Patent Application
20210317258
The present disclosure relates to polymeric materials that include uretdione-containing materials, such as two-part compositions.
Two-part urethane adhesives and sealants are commercially available from a variety of companies. These systems typically involve one component that is an oligomer/polymer terminated with isocyanate groups and a second component that is a polyol. When mixed, the isocyanate reacts with polyol to form carbamate groups. While this is established and effective chemistry, it suffers from a sensitivity to moisture due to ability of the isocyanate to be deactivated when reacted with water. Hence, there remains a need for adhesives and sealants that advantageously have less sensitivity to water.
In a first aspect, a polymeric material is provided. The polymeric material includes a polymerized reaction product of a polymerizable composition including components, a polythiol having an average sulfhydryl group functionality of 2 or greater, and an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (a) a uretdione-containing material including a reaction product of a diisocyanate reacted with itself, (b) a first hydroxyl-containing compound having more than one OH group; and (c) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
In a second aspect, a two-part composition is provided. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
In a third aspect, a polymerized product is provided. The polymerized product is of a two-part composition. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
In a fourth aspect, a method of adhering two substrates together is provided. The method includes (a) obtaining a two-part composition; (b) combining at least a portion of the first part with at least a portion of the second part to form a mixture; (c) disposing at least a portion of the mixture on a first major surface of a first substrate; and (d) contacting a first major surface of a second substrate with the mixture disposed on the first substrate. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
In a fifth aspect, a method of curing a two-part composition is provided. The method includes (a) obtaining a two-part composition; (b) combining at least a portion of the first part with at least a portion of the second part to form a mixture; and (c) disposing the mixture on a first major surface of a substrate. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
The inclusion of polythiol decreases the viscosity of the uretdione-containing material, and the inclusion of the acid stabilizer inhibits reaction of the polythiol with the uretdione-containing material during storage.
The above summary is not intended to describe each embodiment or every implementation of aspects of the invention. The details of various embodiments are set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims.
Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.
The present disclosure provides polymeric materials, polymerizable compositions, and two-part compositions useful for instance in sealants, coatings and/or adhesives that have good flowability and reactivity (e.g., without added solvent), acceptable cure and/or adhesion in a desired amount of time, as compared to similar compositions instead containing isocyanates. Further, sealants, coatings and adhesives according to at least certain embodiments of the present disclosure are essentially free of isocyanates. This is advantageous because isocyanates tend to be sensitizers upon first contact (e.g., to skin) such that subsequent contact causes inflammation. Sealants/coatings/adhesives containing isocyanates exhibit more sensitivity to water than other compounds, as noted above, so minimizing an isocyanate content may improve reliability during curing as well as simplify storage and handling of the polymeric materials, polymerizable compositions, and two-part compositions.
The terms “a”, “an”, “the”, “at least one”, and “one or more” are used interchangeably.
The term “and/or” means one or both such as in the expression A and/or B refers to A alone, B alone, or to both A and B.
The term “essentially” means 95% or more.
The term “equivalents” refers to the number of moles of a functional group (e.g., OH groups, isocyanate groups, uretdione groups, etc.) per molecule of a polymer chain or per mole of a different functional group.
the term “amidine group” does not refer an amidine group in an imidazole ring, although the amidine group may be contained in one or more other rings (e.g., 1,5-diazabicyclo[4.3.0]non-5-ene or 1,8-diazabicyclo[5.4.0]undec-7-ene);
The term “alkyl” refers to a monovalent radical of an alkane. Suitable alkyl groups can have up to 50 carbon atoms, up to 40 carbon atoms, up to 30 carbon atoms, up to 20 carbon atoms, up to 16 carbon atoms, up to 12 carbon atoms, up to 10 carbon atoms, up to 8 carbon atoms, up to 6 carbon atoms, up to 4 carbon atoms, or up to 3 carbon atoms. The alkyl groups can be linear, branched, cyclic, or a combination thereof. Linear alkyl groups often have 1 to 30 carbon atoms, 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Branched alkyl groups often have 3 to 50 carbon atoms, 3 to 40 carbon atoms, 4 to 20 carbon atoms, 3 to 10 carbon atoms, or 3 to 6 carbon atoms. Cyclic alkyl groups often have 3 to 50 carbon atoms, 5 to 40 carbon atoms, 6 to 20 carbon atoms, 5 to 10 carbon atoms, or 6 to 10 carbon atoms.
The term “alkylene” refers to a divalent group that is a radical of an alkane. The alkylene can be straight-chained, branched, cyclic, or combinations thereof. The alkylene typically has 1 to 20 carbon atoms. In some embodiments, the alkylene contains 4 to 14 carbon atoms, 1 to 10 carbon atoms, 1 to 8 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. The radical centers of the alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms. In certain embodiments, the alkylene can be substituted with an OH group.
The term “alkane-triyl” refers to a trivalent radical of an alkane.
The term “aryl” refers to a monovalent group that is radical of an arene, which is a carbocyclic, aromatic compound. The aryl can have one to five rings that are connected to or fused to the aromatic ring. The other ring structures can be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.
The term “aralkyl” refers to a monovalent group of formula —R—Ar where R is an alkylene and Ar is an aryl group. That is, the aralkyl is an alkyl substituted with an aryl.
The term “aralkylene” refers to a divalent group of formula —R—Ara— where R is an alkylene and Ara is an arylene (i.e., an alkylene is bonded to an arylene).
The term “arylene” refers to a divalent group that is carbocyclic and aromatic. The group has one to five rings that are connected, fused, or combinations thereof. The other rings can be aromatic, non-aromatic, or combinations thereof. In some embodiments, the arylene group has up to 5 rings, up to 4 rings, up to 3 rings, up to 2 rings, or one aromatic ring. For example, the arylene group can be phenylene. The term “alkarylene” refers to a divalent group that is an arylene group substituted with an alkyl group or an arylene group attached to an alkylene group. Unless otherwise indicated, the alkarylene group typically has from 1 to 20 carbon atoms, 4 to 14 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Unless otherwise indicated, for both groups, the alkyl or alkylene portion typically has from 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Unless otherwise indicated, for both groups, the aryl or arylene portion typically has from 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 16 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms. In certain embodiments, the arylene group or the alkarylene group has 4 to 14 carbon atoms.
The term “aprotic” refers to a component that does not have a hydrogen atom bound to an oxygen (as in a hydroxyl group) or a nitrogen (as in an amine group). In general terms, any component that does not contain labile H+ is called an aprotic component. The molecules of such components cannot donate protons (H+) to other components.
The term “basic salt” refers to a salt that forms a basic solution if dissolved in water having a pH of 7. The salt may be associated with other substances such as, e.g., water (i.e., a hydrate).
The term “carbamate” refers to a compound having the general formula R—N(H)—C(O)—O—R′. Preferred R groups include alkylene groups.
The term “diisocyanate” refers to a compound having the general formula O═C═N—R—N═C═O. Preferred R groups include alkylene and arylene groups.
The term “diol” refers to a compound with two OH groups.
The term “nonacidic” means free of acidic groups that are at least as acidic as the corresponding carboxyl group.
The term “sulfhydryl group” refers to the —SH group.
The term “triamine” refers to a compound with three amino groups.
The term “polyester” refers to repeating difunctional polymer wherein the repeat units are joined by ester linkages. Ester groups have the general formula —R—C(O)—OR′. The term “polyether” refers to repeating difunctional alkoxy radicals having the general formula —O—R—. Preferred R and R′ groups have the general formula —CnH2n— and include, for example, methylene, ethylene and propylene (including n-propylene and i-propylene) or a combination thereof. Combinations of R and R′ groups may be provided, for example, as random or block type copolymers.
The term “polyol” refers to a compound with two or more hydroxyl (i.e., OH) groups.
The term “polymeric material” refers to any homopolymer, copolymer, terpolymer, and the like, as well as any diluent.
The term “non-reactive diluent” refers to a component that can be added to adjust the viscosity of the polymerizable composition. By “non-reactive” it is meant that the diluent does not participate in a polymerization reaction (e.g., with a curative, a uretdione-containing material, or a hydroxyl-containing compound having one or more OH groups), of the polymerizable composition. The diluent does not react with such components during manufacture of a two-part composition, during manufacture of a sealant, coating, or adhesive, during application of the coating or adhesive to a substrate, or upon aging. Typically, the diluent is substantially free of reactive groups. In some embodiments, the molecular weight of the unreactive diluent is less than the molecular weight of components such as the uretdione-containing material. The non-reactive diluent is not volatile, and substantially remains in the sealant, coating, or adhesive after curing. The boiling point of the non-reactive diluent may be greater than 200° C.
The term “reactive diluent” refers to a component that can be added to adjust the viscosity of the polymerizable composition and does participate in a polymerization reaction (e.g., with a curative, a uretdione-containing material, or a hydroxyl-containing compound having one or more OH groups), of the polymerizable composition. The diluent reacts with such components during at least one of: during application of the sealant, coating, or adhesive to a substrate or upon aging. The diluent includes one or more reactive groups, such as epoxy groups. In some embodiments, the molecular weight of the reactive diluent is less than the molecular weight of components such as the uretdione-containing material.
The term “primary alcohol” refers to an alcohol in which the OH group is connected to a primary carbon atom (e.g., having the general formula —CH2OH). The term “secondary alcohol” refers to an alcohol in which the OH group is connected to a secondary carbon atom (e.g., having the general formula —CHROH, where R is a group containing a carbon atom).
The term “ambient temperature” refers to a temperature in the range of 20 degrees Celsius to 25 degrees Celsius, inclusive.
The term “liquid” refers to the state of matter that is not solid or gas, which has a definite volume and an indefinite shape. Liquids encompass emulsions, suspensions, solutions, and pure components (e.g., polymeric resins) and exclude (e.g., solid) powders and particulates.
In a first aspect, a polymeric material is provided. The polymeric material includes a polymerized reaction product of a polymerizable composition including components, a polythiol having an average sulfhydryl group functionality of 2 or greater, and an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (a) a uretdione-containing material including a reaction product of a diisocyanate reacted with itself, (b) a first hydroxyl-containing compound having more than one OH group; and (c) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol. Stated another way, the first aspect provides:
A polymeric material comprising: a polymerized reaction product of a polymerizable composition comprising components, the components comprising:
A uretdione can be formed by the reaction of a diisocyanate with itself and has the following general formula:
In some embodiments, the diisocyanate comprises a functional group selected from Formula X, Formula XI, and Formula XII:
There are a variety of reaction products that can occur as a diisocyanate reacts with itself, and typically the reaction of a diisocyanate with itself results in a blend of two or more reaction products. Preferably, the reaction of a diisocyanate with itself proceeds to a degree such that the polymeric material contains 25% by weight or less or 23% by weight or less of isocyanate groups, as determined by infrared Fourier Transform spectroscopy (e.g., a Nicolet 6700 FT-IP Spectrometer, Thermo Scientific (Madison, Wis.)) where the weight percent of isocyanate in a material is calculated as the moles of isocyanate functional groups multiplied by 42 grams per mole (g/mol) and divided by the mass of the material.
In certain embodiments, the uretdione-containing material comprises a compound of Formula I:
wherein R1 is independently selected from a C4 to C14 alkylene, arylene, and alkaralyene. In some embodiments, the diisocyanate comprises hexamethylene diisocyanate. One preferable uretdione-containing material is a hexamethylene diisocyanate-based blend of materials comprising uretdione functional groups, commercially available under the trade name DESMODUR N3400 from Covestro (Leverkusen, Germany). Additional uretdione-containing materials are commercially available under the trade name CRELAN EF 403 also from Covestro, and under the trade name METALINK U/ISOQURE TT from Isochem Incorporated (New Albany, Ohio).
Typically, the polymeric material comprises greater than one uretdione functional group in a backbone of the polymeric material, such as an average of 1.1 or greater of a uretdione functional group in a backbone of the polymeric material, 1.2 or greater, 1.3 or greater, 1.4 or greater, 1.5 or greater, 1.6 or greater, 1.8 or greater, 2.0 or greater, 2.2 or greater, 2.4 or greater, 2.6 or greater, 2.8 or greater, 3.0 or greater, 3.2 or greater, 3.4 or greater, or 3.6 or greater; and an average of 6.0 or less of a uretdione functional group in a backbone of the polymeric material, 5.8 or less, 5.6 or less, 5.4 or less, 5.2 or less, 5.0 or less, 4.8 or less, 4.6 or less, 4.4 or less, 4.2 or less, 4.0 or less, 3.8 or less, 3.5 or less, 3.3 or less, 3.1 or less, 2.9 or less, 2.7 or less, 2.5 or less, 2.3 or less, 2.1 or less, or even an average of 1.9 or less of a uretdione functional group in a backbone of the polymeric material. Stated another way, the polymeric material may comprise an average of 1.3 to 6.0, inclusive, or 1.5 to 4.0, inclusive, of a uretdione functional group in a backbone of the polymeric material. In select embodiments, the polymeric material comprises an average of 1.3 to 5.0, inclusive, of a uretdione functional group in a backbone of the polymeric material and the polymerizable composition is free of the second hydroxyl-containing compound. The amount of the uretdione functional group can be determined as described in the Examples below. In some embodiments, the uretdione-containing material is present in an amount of 10% by weight or greater, based on the total weight of the polymeric material, 15% by weight or greater, 20% by weight or greater, 25% by weight or greater, 30% by weight or greater, 35% by weight or greater, 40% by weight or greater, 45% by weight or greater, or 50% by weight or greater, based on the total weight of the polymeric material. In some embodiments, the uretdione-containing material is present in an amount of 90% by weight or less, based on the total weight of the polymeric material.
One exemplary simplified general reaction scheme of a uretdione-containing material with a first-hydroxyl-containing compound and an (optional) second hydroxyl-containing compound is provided below in Scheme 1:
In the particular reaction scheme of Scheme 1, the uretdione-containing material comprises two compounds containing uretdione groups, one of which also contains an isocyanurate compound. In certain embodiments of the polymeric material, the polymeric material comprises an average of 1.3 or fewer isocyanurate units per molecule of the polymeric material. This can be because isocyanurate units may not contribute desirable properties to the polymeric material.
Similarly, an exemplary simplified general reaction scheme of a uretdione-containing material with a first-hydroxyl-containing compound, but without the optional second hydroxyl-containing compound is provided below in Scheme 2:
The polymeric material also typically comprises one or more carbamate functional groups per molecule of the polymeric material in a backbone of the polymeric material. The carbamate functional groups are formed by the reaction of the first hydroxyl-containing compound (and optionally the second hydroxyl-containing compound) with the isocyanate groups present on uretdione-containing compounds. For example, the polymeric material may comprise an average of 0.2 or greater of carbamate functional groups in the backbone of the polymeric material, 0.5 or greater, 1 or greater, 2 or greater, 3 or greater, 4 or greater, 5 or greater, 6 or greater, 7 or greater, or an average of 8 or greater of carbamate functional groups in the backbone of the polymeric material; and an average of 18 or less of carbamate functional groups in the backbone of the polymeric material, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or an average of 9 or less of carbamate functional groups in the backbone of the polymeric material. Stated another way, the polymeric material may comprise an average of 0.2 to 18, inclusive, or 2 to 10, inclusive, of carbamate functional groups in the backbone of the polymeric material. The average carbamate functional group content of the polymeric material can be determined as described in the Examples below.
In certain embodiments, the first hydroxyl-containing compound is an alkylene polyol, a polyester polyol, or a polyether polyol. Often the first hydroxyl-containing compound is a diol, such as a branched diol. For example, in some embodiments the first hydroxyl-containing compound is of Formula II:
HO—R2—OH
wherein R2 is selected from R3, an alkylene, and an alkylene substituted with an OH group, wherein R3 is of Formula III or Formula IV:
wherein each of R4, R5, R6, R7, and R8 is independently an alkylene, wherein each of v and y is independently 1 to 40, and wherein x is selected from 0 to 40. Optionally, R2 is selected from C1 to C20 alkylene and a C1 to C20 alkylene substituted with an OH group.
In certain embodiments of the first hydroxyl-containing compound, each of R4, R5, R6, R7, and R8 is independently selected from a C1 to C20 alkylene. Alternatively, the first hydroxyl-containing compound can be of Formula V or Formula VI:
wherein each of R9 and R11 is independently an alkane-triyl, wherein each of R10 and R12 is independently selected from an alkylene, and wherein each of w and z is independently selected from 1 to 20. Preferably, each of R10 and R12 is independently selected from a C1 to C20 alkylene.
Suitable first hydroxyl-containing compounds include branched alcohols, secondary alcohols, or ethers, for instance and without limitation, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol, poly(tetramethylene ether) glycol, 2-ethylhexane-1,3-diol, and 1,3-butanediol. Such suitable first hydroxyl-containing compounds are commercially available from chemical suppliers including for example, Alfa Aesar (Ward Hill, Mass.), JT Baker (Center Valley, Pa.), TCI (Portland, Oreg.), and Fisher Scientific (Waltham, Mass.).
In certain embodiments, the optional second hydroxyl-containing compound is an alkyl alcohol, a polyester alcohol, or a polyether alcohol, such as a branched alcohol and/or a secondary alcohol. For example, in some embodiments the second hydroxyl-containing compound is present and is of Formula VII:
R13—OH VII;
wherein R13 is selected from R14, R15, and a C1 to C50 alkyl;
wherein R14 is of Formula VIII:
wherein m=1 to 20, R16 is an alkyl, and R17 is an alkylene;
wherein R15 is of Formula IX:
wherein n=1 to 20, R18 is an alkyl, and R19 is an alkylene. Preferably, R13 is a C4-C20 alkyl, as the alkyl groups below C4 have a tendency to form a crystalline polymeric material.
Suitable optional second hydroxyl-containing compounds can include branched alcohols or secondary alcohols, for instance and without limitation, 2-butanol, 2-ethyl-1-hexanol, isobutanol, and 2-butyl-octanol, each of which is commercially available from Alfa Aesar (Ward Hill, Mass.).
In an embodiment, the first hydroxyl-containing compound is of Formula II and the optional second hydroxyl-containing compound is present and is of Formula VII, wherein R2 of the compound of Formula II is of Formula III, and wherein R13 of the compound of Formula VII is a branched C4 to C20 alkyl.
In select embodiments, the first hydroxyl-containing compound is a diol and the reaction product comprises 0.2 to 0.65, inclusive, or 0.25 to 0.61, inclusive, of diol equivalents relative to isocyanate equivalents. Optionally, a sum of the OH equivalents of the first hydroxyl-containing compound and the (optional) second hydroxyl-containing compound is equal to or greater than the isocyanate equivalents of the polymeric material.
Preferably, the polymeric material is essentially free of isocyanates. By “essentially free of isocyanates” it is meant that the polymeric material contains 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, or 1% by weight or less of isocyanate groups, as determined by infrared Fourier Transform spectroscopy (e.g., a Nicolet 6700 FT-IP Spectrometer, Thermo Scientific (Madison, Wis.)), where the weight percent of isocyanate in a material is calculated as the moles of isocyanate functional groups multiplied by 42 g/mol and divided by the mass of the material.
Many thiol-containing compounds having at least two thiol groups (i.e., polythiols) are useful in polymeric materials according to the present disclosure. In some embodiments, a polythiol may be an alkylene, arylene, alkylarylene, arylalkylene, or alkylenearylalkylene having at least two mercaptan groups, wherein any of the alkylene, alkylarylene, arylalkylene, or alkylenearylalkylene are optionally interrupted by one or more oxa (i.e., —O—), thia (i.e., —S—), or imino groups (i.e., —NR24— wherein R24 is a hydrocarbyl group or H), and optionally substituted by alkoxy or hydroxyl.
Examples of useful dithiols include 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,3-pentanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,3-dimercapto-3-methylbutane, dipentenedimercaptan, ethylcyclohexyldithiol (ECHDT), dimercaptodiethyl sulfide, methyl-substituted dimercaptodiethyl sulfide, dimethyl-substituted dimercaptodiethyl sulfide, dimercaptodioxaoctane, 1,5-dimercapto-3-oxapentane, benzene-1,2-dithiol, benzene-1,3-dithiol, benzene-1,4-dithiol, and tolylene-2,4-dithiol. Examples of polythiols having more than two mercaptan groups include propane-1,2,3-trithiol; 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane; tetrakis(7-mercapto-2,5-dithiaheptyl)methane; and trithiocyanuric acid.
Also useful are polythiols formed from the esterification of polyols with thiol-containing carboxylic acids or their derivatives. Examples of polythiols formed from the esterification of polyols with thiol-containing carboxylic acids or their derivatives include those made from the esterification reaction between thioglycolic acid or 3-mercaptopropionic acid and several polyols to form the mercaptoacetates or mercaptopropionates, respectively. Examples of polythiol compounds preferred because of relatively low odor level include, but are not limited to, esters of thioglycolic acid, α-mercaptopropionic acid, and β-mercaptopropionic acid with polyhydroxy compounds (polyols) such as diols (e.g., glycols), triols, tetraols, pentaols, and hexaols. Specific examples of such polythiols include, but are not limited to, ethylene glycol bis(thioglycolate), ethylene glycol bis(β-mercaptopropionate), trimethylolpropane tris(thioglycolate), trimethylolpropane tris(β-mercaptopropionate) and ethoxylated versions, pentaerythritol tetrakis(thioglycolate), pentaerythritol tetrakis(β-mercaptopropionate), and tris(hydroxyethyl)isocyanurate tris(β-mercaptopropionate). However, in those applications where concerns about possible hydrolysis of the ester exists, these polyols are typically less desirable.
Suitable polythiols also include those commercially available as THIOCURE PETMP (pentaerythritol tetra(3-mercaptopropionate)), TMPMP (trimethylolpropane tri(3-mercaptopropionate)), ETTMP (ethoxylated trimethylolpropane tri(3-mercaptopropionate) such as ETTMP 1300 and ETTMP 700), GDMP glycol di(3-mercaptopropionate), TMPMA (trimethylolpropane tri(mercaptoacetate)), TEMPIC (tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate), and PPGMP (propylene glycol 3-mercaptopropionate) from Bruno Bock Chemische Fabrik GmbH & Co. KG. A specific example of a polymeric polythiol is polypropylene-ether glycol bis(β-mercaptopropionate), which is prepared from polypropylene-ether glycol (e.g., PLURACOL P201, Wyandotte Chemical Corp.) and β-mercaptopropionic acid by esterification.
Suitable polythiols also include those prepared from esterification of polyols with thiol-containing carboxylic acids or their derivatives, those prepared from a ring-opening reaction of epoxides with H2S (or its equivalent), those prepared from the addition of H2S (or its equivalent) across carbon-carbon double bonds, polysulfides, polythioethers, and polydiorganosiloxanes. Specifically, these include the 3-mercaptopropionates (also referred to as β-mercaptopropionates) of ethylene glycol and trimethylolpropane (the former from Chemische Fabrik GmbH & Co. KG, the latter from Sigma-Aldrich); POLYMERCAPTAN 805C (mercaptanized castor oil); POLYMERCAPTAN 407 (mercaptohydroxy soybean oil) from Chevron Phillips Chemical Co. LLP, and CAPCURE, specifically CAPCURE 3-800 (a polyoxyalkylenetriol with mercapto end groups of the structure R25[O(C3H6O)nCH2CH(OH)CH2SH]3 wherein R25 represents an aliphatic hydrocarbon group having 1-12 carbon atoms and n is an integer from 1 to 25), from Gabriel Performance Products, Ashtabula, Ohio, and GPM-800, which is equivalent to CAPCURE 3-800, also from Gabriel Performance Products.
Examples of oligomeric or polymeric polythioethers useful for practicing the present disclosure are described, for example, in U.S. Pat. No. 4,366,307 (Singh et al.), U.S. Pat. No. 4,609,762 (Morris et al.), U.S. Pat. No. 5,225,472 (Cameron et al.), U.S. Pat. No. 5,912,319 (Zook et al.), U.S. Pat. No. 5,959,071 (DeMoss et al.), U.S. Pat. No. 6,172,179 (Zook et al.), and U.S. Pat. No. 6,509,418 (Zook et al.).
In some embodiments, the polythiol is oligomeric or polymeric. Examples of useful oligomeric or polymeric polythiols include polythioethers and polysulfides. Polythioethers include thioether linkages (i.e., —S—) in their backbone structures. Polysulfides include disulfide linkages (i.e., —S—S—) in their backbone structures.
In some embodiments, the polythiol has an average sulfhydryl group functionality of 2.5 or greater, 2.75 or greater, 3 or greater, 3.25 or greater, 3.5 or greater, 3.75 or greater, or 4 or greater; and up to 6 average sulfhydryl group functionality.
Polythioethers can be prepared, for example, by reacting dithiols with dienes, diynes, divinyl ethers, diallyl ethers, ene-ynes, alkynes, or combinations of these under free-radical conditions. Useful dithiols include any of the dithiols listed above. Examples of suitable divinyl ethers include divinyl ether, ethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, polytetrahydrofuryl divinyl ether, and combinations of any of these. Useful divinyl ethers of formula CH2═CHO(R26O)mCH═CH2, in which m is a number from 0 to 10, R26 is C2 to C6 branched alkylene. Such compounds can be prepared by reacting a polyhydroxy compound with acetylene. Examples of compounds of this type include compounds in which R26 is an alkyl-substituted methylene group such as —CH(CH3)— (e.g., those obtained from BASF, Florham Park, N.J., as “PLURIOL”, for which R26 is ethylene and m is 3.8) or an alkyl-substituted ethylene (e.g., —CH2CH(CH3)— such as those obtained from International Specialty Products of Wayne, N.J., as “DPE” (e.g., DPE-2 and DPE-3). Examples of other suitable dienes, diynes, and diallyl ethers include 4-vinyl-1-cyclohexene, 1,5-cyclooctadiene, 1,6-heptadiyne, 1,7-octadiyne, and diallyl phthalate. Small amounts of trifunctional compounds (e.g., triallyl-1,3,5-triazine-2,4,6-trione, 2,4,6-triallyloxy-1,3,5-triazine) may also be useful in the preparation of oligomers.
Examples of oligomeric or polymeric polythioethers useful for practicing the present disclosure are described, for example, in U.S. Pat. No. 4,366,307 (Singh et al.), U.S. Pat. No. 4,609,762 (Morris et al.), U.S. Pat. No. 5,225,472 (Cameron et al.), U.S. Pat. No. 5,912,319 (Zook et al.), U.S. Pat. No. 5,959,071 (DeMoss et al.), U.S. Pat. No. 6,172,179 (Zook et al.), and U.S. Pat. No. 6,509,418 (Zook et al.). In some embodiments, the polythioether is represented by formula HSR27[S(CH2)2O[R28O]m(CH2)2SR27]nSH, wherein each R27 and R28 is independently a C2-6 alkylene, wherein alkylene may be straight-chain or branched, C6-8 cycloalkylene, C6-10 alkylcycloalkylene, —[(CH2)pX]q(CH2)r in which at least one —CH2— is optionally substituted with a methyl group, X is one selected from the group consisting of O, S and —NR29—, where R29 denotes hydrogen or methyl, m is a number from 0 to 10, n is a number from 1 to 60, p is an integer from 2 to 6, q is an integer from 1 to 5, and r is an integer from 2 to 10. Polythioethers with more than two mercaptan groups may also be useful.
Polythioethers can also be prepared, for example, by reacting dithiols with diepoxides, which may be carried out by stirring at room temperature, optionally in the presence of a tertiary amine catalyst (e.g., 1,4-diazabicyclo[2.2.2]octane (DABCO)). Useful dithiols include any of those described above. Useful epoxides can be any of those having two epoxide groups. In some embodiments, the diepoxide is a bisphenol diglycidyl ether, wherein the bisphenol (i.e., —OC6H5CH2C6H5O—) may be unsubstituted (e.g., bisphenol F), or either of the phenyl rings or the methylene group may be substituted by halogen (e.g., fluoro, chloro, bromo, iodo), methyl, trifluoromethyl, or hydroxymethyl. Polythioethers prepared from dithiols and diepoxides have pendent hydroxyl groups and can have structural repeating units represented by formula —SR27SCH2CH(OH)CH2OC6H5CH2C6H5OCH2CH(OH)CH2SR27S—, wherein R27 is as defined above, and the bisphenol (i.e., —OC6H5CH2C6H5O—) may be unsubstituted (e.g., bisphenol F), or either of the phenyl rings or the methylene group may be substituted by halogen (e.g., fluoro, chloro, bromo, iodo), methyl, trifluoromethyl, or hydroxymethyl. Mercaptan terminated polythioethers of this type can also be reacted with any of the dienes, diynes, divinyl ethers, and diallyl ethers.
Other useful polythiols can be formed from the addition of hydrogen sulfide (H2S) (or its equivalent) across carbon-carbon double bonds. For example, dipentene and triglycerides which have been reacted with H2S (or its equivalent). Specific examples include dipentene dimercaptan and those polythiols available as POLYMERCAPTAN 358 (mercaptanized soybean oil) and POLYMERCAPTAN 805C (mercaptanized castor oil) from Chevron Phillips Chemical Co. LLP. At least for some applications, the preferred polythiols are POLYMERCAPTAN 358 and 805C since they are produced from largely renewable materials, i.e., the triglycerides, soybean oil and castor oil, and have relatively low odor in comparison to many thiols. Useful triglycerides have at least two sites of unsaturation, i.e., carbon-carbon double bonds, per molecule on average, and sufficient sites are converted to result in at least 2 thiols per molecule on average. In the case of soybean oil, this requires a conversion of approximately 42 percent or greater of the carbon-carbon double bonds, and in the case of castor oil this requires a conversion of approximately 66 percent or greater of the carbon-carbon double bonds. Typically, higher conversion is preferred, and POLYMERCAPTAN 358 and 805C can be obtained with conversions greater than approximately 60 percent and 95 percent, respectively. Useful polythiols of this type also include those derived from the reaction of H2S (or its equivalent) with the glycidyl ethers of bisphenol A epoxy resins, bisphenol F epoxy resins, and novolak epoxy resins. A preferred polythiol of this type is QX11, derived from bisphenol A epoxy resin, from Japan Epoxy Resins (JER) as EPOMATE. Other polythiols suitable include those available as EPOMATE QX10 and EPOMATE QX20 from JER.
Still other useful polythiols are polysulfides that contain thiol groups such as those available as THIOKOL LP-2, LP-3, LP-12, LP-31, LP-32, LP-33, LP-977, and LP-980 from Toray Fine Chemicals Co., Ltd., and polythioether oligomers and polymers such as those described in PCT Publ. No. WO 2016130673 A1 (DeMoss et al.).
In some embodiments, the polythiol includes a primary thiol, a secondary thiol, or both.
In any embodiment, the polythiol is present in the polymeric material in an amount of 5% by weight or more, based on the total weight of the polymeric material, 7% by weight or more, 10% by weight or more, 12% by weight or more, 15% by weight or more, 17% by weight or more, 20% by weight or more, 22% by weight or more, 25% by weight or more, 27% by weight or more, or 30% by weight or more; and 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, or 35% by weight or less, based on the total weight of the polymeric material. Stated another way, the polythiol may be present in an amount of 5% to 50% by weight or 10% to 35% by weight, for instance, based on the total weight of the polymeric material.
In some embodiments, the polythiol and acidic stabilizer are not present at the time of the polymerization of the polymerizable composition containing the components of (a) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (b) a first hydroxyl-containing compound having more than one OH group, and, if present, (c) a second hydroxyl-containing compound having a single OH group. In such embodiments, components (a), (b), and, if present, (c), are reacted, and then at least one of the polythiol and acidic stabilizer is combined with the reaction product of components (a), (b), and, if present, (c).
In alternate embodiments, the acidic stabilizer is present at the time of reaction of components (a), (b), and, if present, (c). In such embodiments, it is preferred that most or all the acidic stabilizer does not participate in the polymerization of the polymerizable components including components (a), (b), and, if present, (c), but rather remains available for inhibiting reaction of the polythiol with the uretdione-containing material.
An acidic stabilizer is added to the polymeric material to inhibit the polythiol curative by an acid-base interaction, thereby prolonging the working time and/or storage stability of the polymeric material. It has been discovered that the inclusion of the acidic stabilizer unexpectedly minimizes reaction of the polythiol curative without preventing the base catalyzed cure chemistry of the thiol and uretdione components. Exemplary acidic stabilizers include carboxylic acids (including fluorinated carboxylic acids), phosphonic acids (including fluorinated carboxylic acids), sulfonic acids (including fluorinated carboxylic acids), perfluorosulfonimides, and Lewis acids (e.g., BF3). In some embodiments, the acidic stabilizer is selected from the group consisting of BF3, C1-C16 monocarboxylic acids, C1-C16 dicarboxylic acids, C6-C14 arylcarboxylic acids, C1-C16 monosulfonic acids, C1-C16 disulfonic acids, C6-C14 arylsulfonic acids, C1-C16 monophosphonic acids, C1-C16 diphosphonic acids, C6-C14 arylphosphonic acids, and combination thereof.
The acidic stabilizer may be added in any amount, preferably in an amount of 0.005% to 5.0% by weight, more preferably 0.01% to 1% by weight, based on the total weight of the polymeric material.
In preferred embodiments, the polymeric material contains less than 10 weight percent of total solvent content, preferably less than 5 weight percent of total solvent content, more preferably less than 1 weight percent of total solvent content. In some embodiments, the polymeric material is solvent-free. Typically, the polymeric material is in the form of a liquid, as opposed to a solid (e.g., dry powder, pellets, etc.) despite having a high solids content.
In some embodiments, the polymeric material further includes at least one epoxy component. The introduction of a reactive epoxy diluent also results in an improvement in the viscosity of a polymeric material including a uretdione-containing material, such that use of crystalline or high viscosity uretdione-containing materials has further been enabled. Moreover, due to the similarity in curatives used for both epoxy and uretdione groups, one or more epoxy components can be copolymerized with the uretdione-containing material into a polymer network. Mechanical properties of the polymer network can be influenced by varying the amount of the optional epoxy component.
The epoxy component may optionally include an epoxy resin comprising one or more epoxy compounds that can be monomeric or polymeric, and aliphatic, cycloaliphatic, heterocyclic, aromatic, hydrogenated, and/or a mixture thereof. Preferred epoxy compounds contain more than 1.5 epoxy groups per molecule and more preferably at least 2 epoxide groups per molecule.
The epoxy component can include linear polymeric epoxides having terminal epoxy groups (e.g., a diglycidyl ether of a polyoxyalkylene glycol), polymeric epoxides having skeletal epoxy groups (e.g., polybutadiene poly epoxy), polymeric epoxides having pendant epoxy groups (e.g., a glycidyl methacrylate polymer or copolymer), or a mixture thereof.
Exemplary epoxy compounds include, for example, aliphatic (including cycloaliphatic) and aromatic epoxy compounds. The epoxy compound(s) may be monomeric, oligomeric, or polymeric epoxides, or a combination thereof. The epoxy component may be a pure compound or a mixture comprising at least two epoxy compounds. The epoxy component typically has, on average, at least 1 epoxy (i.e., oxiranyl) group per molecule, preferably at least about 1.5 and more preferably at least about 2 epoxy groups per molecule. Hence, the epoxy component may comprise at least one monofunctional epoxy, and/or may comprise at least one multifunctional epoxy. In some cases, 3 (e.g., trifunctional epoxy), 4, 5, or even 6 epoxy groups may be present, on average. Polymeric epoxides include linear polymers having terminal epoxy groups (e.g., a diglycidyl ether of a polyoxyalkylene glycol), polymers having skeletal oxirane units (e.g., polybutadiene polyepoxide), and polymers having pendent epoxy groups (e.g., a glycidyl methacrylate polymer or copolymer). Other useful epoxy components are polyhydric phenolic formaldehyde condensation products as well as polyglycidyl ethers that contain as reactive groups only epoxy groups or hydroxy groups. In certain embodiments, the epoxy component comprises at least one glycidyl ether group. The “average” number of epoxy groups per molecule can be determined by dividing the total number of epoxy groups in the epoxy-containing material by the total number of epoxy-containing molecules present.
The choice of epoxy component may depend upon the intended end use. For example, epoxides with flexible backbones may be desired where a greater amount of ductility is needed in the bond line. Materials such as diglycidyl ethers of bisphenol A and diglycidyl ethers of bisphenol F can help impart desirable structural adhesive properties upon curing, while hydrogenated versions of these epoxies may be useful for compatibility with substrates having oily surfaces.
Commercially available epoxy compounds include octadecylene oxide, epichlorohydrin, styrene oxide, vinylcyclohexene oxide, glycidol, glycidyl methacrylate, vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexene carboxylate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, bis(2,3-epoxycyclopentyl) ether, dipentene dioxide, silicone resin containing epoxy functionality, flame retardant epoxy resins (e.g., DER-580, a brominated bisphenol type epoxy resin available from Dow Chemical Co.), 1,4-butanediol diglycidyl ether of phenol-formaldehyde novolac (e.g., DEN-431 and DEN-438 from Dow Chemical Co.), and resorcinol diglycidyl ether (e.g., Kopoxite from Koppers Company, Inc.), bis(3,4-epoxycyclohexyl)adipate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexene metadioxane, vinylcyclohexene monoxide 1,2-epoxyhexadecane, alkyl glycidyl ethers such as (e.g., HELOXY Modifier 7 from Momentive Specialty Chemicals, Inc., Waterford, N.Y.), alkyl C12-C14 glycidyl ether (e.g., HELOXY Modifier 8 from Momentive Specialty Chemicals, Inc.), butyl glycidyl ether (e.g., HELOXY Modifier 61 from Momentive Specialty Chemicals, Inc.), cresyl glycidyl ether (e.g., HELOXY Modifier 62 from Momentive Specialty Chemicals, Inc.), p-tert-butylphenyl glycidyl ether (e.g., HELOXY Modifier 65 from Momentive Specialty Chemicals, Inc.), polyfunctional glycidyl ethers such as diglycidyl ether of 1,4-butanediol (e.g., HELOXY Modifier 67 from Momentive Specialty Chemicals, Inc.), diglycidyl ether of neopentyl glycol (e.g., HELOXY Modifier 68 from Momentive Specialty Chemicals, Inc.), diglycidyl ether of cyclohexanedimethanol (e.g., HELOXY Modifier 107 from Shell Chemical Co.), trimethylolethane triglycidyl ether (e.g., HELOXY Modifier 44 from Momentive Specialty Chemicals, Inc.), trimethylolpropane triglycidyl ether (e.g., HELOXY Modifier 48 from Momentive Specialty Chemicals, Inc.), polyglycidyl ether of an aliphatic polyol (e.g., HELOXY Modifier 84 from Momentive Specialty Chemicals, Inc.), polyglycol diepoxide (e.g., HELOXY Modifier 32 from Momentive Specialty Chemicals, Inc.), bisphenol F epoxides, 9,9-bis[4-(2, 3-epoxypropoxy)phenyl]fluorenone (e.g., EPON 1079 from Momentive Specialty Chemicals, Inc.).
In certain embodiments, the epoxy component comprises an epoxidised (poly)olefinic resin, an epoxidised phenolic novolac resin, an epoxidised cresol novolac resin, a cycloaliphatic epoxy resin, or a combination thereof. Commercially available epoxy resins include for instance, epoxidised linseed oil (e.g., VIKOFLEX 7190 from Arkema Inc., King of Prussia, Pa.), epoxy phenol novolac resin (e.g., EPALLOY 8250 from CVC Specialty Chemicals, Moorestown, N.J.), multifunctional ephichlorohydrin/cresol novolac epoxy resin (e.g., EPON 164 from Hexion Specialty Chemicals GmbH, Rosbach, Germany), and cycloaliphatic epoxy resin (e.g., CELLOXIDE 2021 from Daicel Chemical Industries, Ltd., Tokyo, Japan).
In some embodiments, the epoxy component contains one or more epoxy compounds having an epoxy equivalent weight of from 80 g/mole to 1500 g/mol. More preferably, the epoxy resin contains one or more epoxy compounds having an epoxy equivalent weight of from 100 g/mole to 1200 g/mole. In some cases, the curable composition contains two or more epoxy compounds.
Useful epoxy compounds also include glycidyl ethers, e.g., such as those prepared by reacting a polyhydric alcohol with epichlorohydrin. Such polyhydric alcohols may include butanediol, polyethylene glycol, and glycerin.
Useful epoxy compounds also include aromatic glycidyl ethers, e.g., such as those prepared by reacting a polyhydric phenol with an excess of epichlorohydrin, cycloaliphatic glycidyl ethers, hydrogenated glycidyl ethers, and mixtures thereof. Such polyhydric phenols may include resorcinol, catechol, hydroquinone, and the polynuclear phenols such as p,p′-dihydroxydibenzyl, p,p′-dihydroxydiphenyl, p,p′-dihydroxyphenyl sulfone, p,p′-dihydroxybenzophenone, 2,2′-dihydroxy-1,1-dinaphthylmethane, and the 2,2′-, 2,3′-, 2,4′-, 3,3′-, 3,4′-, and 4,4′-isomers of dihydroxydiphenylmethane, dihydroxydiphenyldimethylmethane, dihydroxydiphenylethylmethylmethane, dihydroxydiphenylmethylpropylmethane, dihydroxy-diphenylethylphenylmethane, dihydroxydiphenylpropylphenylmethane, dihydroxydiphenylbutylphenylmethane, dihydroxydiphenyltolylethane, dihydroxydiphenyltolylmethylmethane, dihydroxydiphenyldicyclohexylmethane, and dihydroxydiphenylcyclohexane.
Similarly, useful epoxy compounds also include a polyglycidyl ether of a polyhydric phenol. Example polyglycidyl ethers of a polyhydric phenol include a polyglycidyl ether of bisphenol A, bisphenol F, bisphenol AD, catechol, or resorcinol.
Useful epoxy compounds also include glycidyl ether esters and polyglycidyl esters. A glycidyl ether ester may be obtained by reacting a hydroxycarboxylic acid with epichlorohydrin. A polyglycidyl ether may be obtained by reacting a polycarboxylic acid with epichlorohydrin. Such polycarboxylic acids may include a dimer acid (e.g., RADIACID 0950 from Oleon, Simpsonville, S.C.), and a trimer acid (e.g., RADIACID 0983 from Oleon). Suitable glycidyl esters include a glycidyl ester of neodecanoic acid (e.g., ERISYS GS-110 from CVC Specialty Chemicals) and a glycidyl ester of a dimer acid (e.g., DRISYS GS-120 from CVC Specialty Chemicals).
Exemplary epoxy compounds also include glycidyl ethers of bisphenol A, bisphenol F, and novolac resins as well as glycidyl ethers of aliphatic or cycloaliphatic diols. Examples of commercially available glycidyl ethers include diglycidyl ethers of bisphenol A such as those available as EPON 828, EPON 1001, EPON 1310, and EPON 1510 from Hexion Specialty Chemicals GmbH, Rosbach, Germany; those available under the trade name D.E.R. (e.g., D.E.R. 331, 332, and 334) from Dow Chemical Co., Midland, Mich.; those available under the trade name EPICLON from Dainippon Ink and Chemicals, Inc. (e.g., EPICLON 840 and 850) and those available under the trade name YL-980 from Japan Epoxy Resins Co., Ltd.); diglycidyl ethers of bisphenol F (e.g., those available under the trade name EPICLON from Dainippon Ink and Chemicals, Inc. (e.g., EPICLON 830)); glycidyl ethers of novolac resins (e.g., novolac epoxy resins, such as those available under the trade name D.E.N. from Dow Chemical Co. (e.g., D.E.N. 425, 431, and 438)); and flame retardant epoxy resins (e.g., D.E.R. 580, a brominated bisphenol type epoxy resin available from Dow Chemical Co.). In some embodiments, aromatic glycidyl ethers, such as those prepared by reacting a dihydric phenol with an excess of epichlorohydrin, may be preferred. In some embodiments, nitrile rubber modified epoxies may be used (e.g., KELPOXY 1341 available from CVC Chemical).
Certain epoxy components can advantageously be used in high amounts, e.g., 45% or more by weight, based on the total weight of a polymerizable composition, and maintain an acceptable structural integrity of a sealant, coating, or adhesive. Such epoxy components preferable for use in amounts of 45 wt. % or greater, 50 wt. %, 55 wt. %, or 60 wt. % or greater, include for instance, a polyglycidyl ether of a polyhydric phenol (preferably a polyglycidyl ether of bisphenol A, bisphenol F, bisphenol AD, catechol, or resorcinol), or at least one of an epoxidised (poly)olefinic resin, epoxidised phenolic novolac resin, epoxidised cresol novolac resin, or a cycloaliphatic epoxy resin.
Low viscosity epoxy compound(s) may be included in the epoxy component, for example, to reduce viscosity as noted above. For instance, in some embodiments, the epoxy component exhibits a dynamic viscosity of 100,000 centipoises (cP) or less, 75,000 cP or less, 50,000 cP or less, 30,000 cP or less, 20,000 cP or less, 15,000 cP or less, 10,000 cP or less, 9,000 cP or less, 8,000 cP or less, 7,000 cP or less, 6,000 cP or less, 5,000 cP or less, 4,000 cP or less, or 3,000 cP or less, as determined using a Brookfield viscometer. Conditions for the dynamic viscosity test include use of a LV4 spindle at a speed of 0.3 or 0.6 revolutions per minute (RPM) at 24 degrees Celsius. In some embodiments, one or more epoxy components each has a molecular weight of 2,000 grams per mole or less. Examples of low viscosity epoxy compounds include: cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, p-tert-butylphenyl glycidyl ether, cresyl glycidyl ether, diglycidyl ether of neopentyl glycol, triglycidyl ether of trimethylolethane, triglycidyl ether of trimethylolpropane, triglycidyl p-aminophenol, N,N′-diglycidylaniline, N,N,N′,N′-tetraglycidyl meta-xylylenediamine, and vegetable oil polyglycidyl ether.
In some embodiments, the amount of the epoxy component is 1% by weight or greater, based on the total weight of the polymeric material, 5% by weight or greater, 7% by weight or greater, 10% by weight or greater, 12% by weight or greater, 15% by weight or greater, 18% by weight or greater; 21% by weight or greater, 24% by weight or greater, 26% by weight or greater, 310% by weight or greater, 36% by weight or greater, 41% by weight or greater, 45% by weight or greater, or 50% by weight or greater, based on the total weight of the polymeric material; and 95% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 31% by weight or less, 29% by weight or less, 27% by weight or less, 25% by weight or less, 23% by weight or less, 20% by weight or less, 17% by weight or less, 14% by weight or less, or 10% by weight or less, based on the total weight of the polymeric material. In select embodiments, the epoxy component is added in an amount of 2 to 80% by weight, 5 to 70% by weight, or 10 to 60% by weight, based on the total weight of the polymeric material.
The components optionally include at least one accelerator, for instance a catalyst. Suitable catalysts include a bismuth carboxylate, for instance bismuth neodecanoate and/or bismuth ethylhexanoate. Typically, such catalysts can be included to accelerate reaction of the uretdione-containing material with one or more hydroxyl-containing compounds. In select embodiments, the components are free of catalysts that contain tin. Further suitable catalysts comprise Lewis acid salts, e.g., calcium triflate, calcium nitrate, and/or lanthanum nitrate, which can be useful when the optional epoxy component is present, for accelerating reaction of one or more of the components with the epoxy component.
The polymeric material may further comprise one or more additives, e.g., plasticizers, non-reactive diluents, toughening agents, fillers, flow control agents, colorants (e.g., pigments and dyes), adhesion promoters, UV stabilizers, flexibilizers, fire retardants, antistatic materials, thermally and/or electrically conductive particles, and expanding agents including, for example, chemical blowing agents such as azodicarbonamide or expandable polymeric microspheres containing a hydrocarbon liquid, such as those sold under the tradename EXPANCEL by Expancel Inc. (Duluth, Ga.).
Suitable non-reactive diluents can include benzoate esters, for instance and without limitation ethyl benzoate, ethylhexyl benzoate, ethylhexyl hydroxystearate benzoate, C12-C15 alkyl benzoates, and dipropylene glycol dibenzoate. A commercially available non-reactive diluent includes the material available under the tradename BENZOFLEX 131 from Eastman Chemical (Kingsport, Tenn.). Additionally, organic and/or inorganic acids can be utilized as retarders to delay the cure or extend the pot-life of the material. For example, suitable acids can include carboxylic acids.
A plasticizer is often added to a polymeric material to make the polymeric material more flexible, softer, and more workable (e.g., easier to process). More specifically, the mixture resulting from the addition of the plasticizer to the polymeric material typically has a lower glass transition temperature compared to the polymeric material alone. The glass transition temperature of a polymeric material can be lowered, for example, by at least 30 degrees Celsius, at least 40 degrees Celsius, at least 50 degrees Celsius, at least 60 degrees Celsius, or at least 70 degrees Celsius by the addition of one or more plasticizers. The temperature change (i.e., decrease) tends to correlate with the amount of plasticizer added to the polymeric material. It is the lowering of the glass transition temperature that usually leads to the increased flexibility, increased elongation, and increased workability. Some example plasticizers include various phthalate esters such as diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diisoheptyl phthalate, dioctyl phthalate, diisooctyl phthalate, dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, and benzylbutyl phthalate; various adipate esters such as di-2-ethylhexyl adipate, dioctyl adipate, diisononyl adipate, and diisodecyl adipate; various phosphate esters such as tri-2-ethylhexyl phosphate, 2-ethylhexyl diphenyl phosphate, trioctylphosphate, and tricresyl phosphate; various trimellitate esters such as tris-2-ethylhexyl trimellitate and trioctyl trimellitate; various sebacate and azelate esters; and various sulfonate esters. Other example plasticizers include polyester plasticizers that can be formed by a condensation reaction of propanediols or butanediols with adipic acid. Commercially available plasticizers include those available under the tradename JAYFLEX DINA available from ExxonMobil Chemical (Houston, Tex.) and PLASTOMOLL (e.g., diisononyl adipate) from BASF (Florham Park, N.J.).
Another optional additive is a toughening agent. Toughening agents can be added to provide the desired overlap shear, peel resistance, and impact strength. Useful toughening agents are polymeric materials that may react with the epoxy resin and that may be cross-linked. Suitable toughening agents include polymeric compounds having both a rubbery phase and a thermoplastic phase or compounds which are capable of forming, with the epoxide resin, both a rubbery phase and a thermoplastic phase on curing. Polymers useful as toughening agents are preferably selected to inhibit cracking of the cured epoxy composition.
Some polymeric toughening agents that have both a rubbery phase and a thermoplastic phase are acrylic core-shell polymers wherein the core is an acrylic copolymer having a glass transition temperature below 0° C. Such core polymers may include polybutyl acrylate, polyisooctyl acrylate, polybutadiene-polystyrene in a shell comprised of an acrylic polymer having a glass transition temperature above 25° C., such as polymethylmethacrylate. Commercially available core-shell polymers include those available as a dry powder under the tradenames ACRYLOID KM 323, ACRYLOID KM 330, and PARALOID BTA 731, from Dow Chemical Co., and KANE ACE B-564 from Kaneka Corporation (Osaka, Japan). These core-shell polymers may also be available as a predispersed blend with a diglycidyl ether of bisphenol A at, for example, a ratio of 12 to 37 parts by weight of the core-shell polymer and are available under the tradenames KANE ACE (e.g., KANE ACE MX 157, KANE ACE MX 257, and KANE ACE MX 125) from Kaneka Corporation (Japan).
Another class of polymeric toughening agents that are capable of forming, with the epoxy component, a rubbery phase on curing, are carboxyl-terminated butadiene acrylonitrile compounds. Commercially available carboxyl-terminated butadiene acrylonitrile compounds include those available under the tradenames HYCAR (e.g., HYCAR 1300X8, HYCAR 1300X13, and HYCAR 1300X17) from Lubrizol Advanced Materials, Inc. (Cleveland, Ohio) and under the tradename PARALOID (e.g., PARALOID EXL-2650) from Dow Chemical (Midland, Mich.).
Other polymeric toughening agents are graft polymers, which have both a rubbery phase and a thermoplastic phase, such as those disclosed in U.S. Pat. No. 3,496,250 (Czerwinski). These graft polymers have a rubbery backbone having grafted thereto thermoplastic polymer segments. Examples of such graft polymers include, for example, (meth)acrylate-butadiene-styrene, and acrylonitrile/butadiene-styrene polymers. The rubbery backbone is preferably prepared so as to constitute from 95 wt. % to 40 wt. % of the total graft polymer, so that the polymerized thermoplastic portion constitutes from 5 wt. % to 60 wt. % of the graft polymer.
Still other polymeric toughening agents are polyether sulfones such as those commercially available from BASF (Florham Park, N.J.) under the tradename ULTRASON (e.g., ULTRASON E 2020 P SR MICRO).
Further optional additives include a flow control agent or thickener, to provide the desired rheological characteristics to the polymeric material. Suitable flow control agents include fumed silica, such as treated fumed silica, available under the tradename CAB-O-SIL TS 720, and untreated fumed silica available under the tradename CAB-O-SIL M5, from Cabot Corp. (Alpharetta, Ga.).
In some embodiments, the polymeric material optimally contains adhesion promoters other than the silane adhesion promoter to enhance the bond to the substrate. The specific type of adhesion promoter may vary depending upon the composition of the surface to which it will be adhered. Adhesion promoters that have been found to be particularly useful for surfaces coated with ionic type lubricants used to facilitate the drawing of metal stock during processing include, for example, dihydric phenolic compounds such as catechol and thiodiphenol.
The polymeric material optionally may also contain one or more fillers (e.g., aluminum powder, carbon black, glass bubbles, talc, clay, calcium carbonate, barium sulfate, titanium dioxide, silica such as fused silica, silicates, glass beads, and mica). Particulate fillers can be in the form of flakes, rods, spheres, and the like.
The amount and type of such additives may be selected by one skilled in the art, depending on the intended end use of the composition.
In certain embodiments, the polymeric material is used in an application where it is disposed between two substrates, wherein solvent removal (e.g., evaporation) is restricted, especially when one or more of the substrates comprises a moisture impermeable material (e.g., steel or glass). In such cases, the polymeric material comprises a solids content of 90% or greater, 92% or greater, 94% or greater, 95% or greater, 96% or greater, 98% or greater, or 99% or greater. Likewise, in such embodiments where solvent removal is restricted, the first part, the second part, or both parts of a two-part composition according to the present disclosure comprises a solids content of 90% or greater, 92% or greater, 94% or greater, 95% or greater, 96% or greater, 98% or greater, or 99% or greater. Components that are considered “solids” include, for instance and without limitation, polymers, oligomers, monomers, hydroxyl-containing compounds, and additives such as plasticizers, catalysts, non-reactive diluents, and fillers. Typically, only solvents do not fall within the definition of solids, for instance water or organic solvents.
For convenient handleability, the polymeric material typically comprises a dynamic viscosity of 10 Poise (P) or greater as determined using a Brookfield viscometer, 50 P or greater, 100 P or greater, 150 P or greater, 250 P or greater, 500 P or greater, 1,000 P or greater, 1,500 P or greater, 2,000 P or greater, 2,500 P or greater, 3,000 P or greater, or 3,500 P or greater; and 30,000 P or less, 25,000 P or less, 20,000 P or less, 18,000 P or less, 15,000 P or less, 12,000 P or less, 10,000 P or less, 9,000 P or less, 8,000 P or less, 7,000 P or less, 6,000 P or less, 5,000 P or less, or even 4,000 P or less, as determined using a Brookfield viscometer. Stated another way, the polymeric material may exhibit a dynamic viscosity of 10 Poise (P) to 30,000 P, inclusive, 10 P to 10,000 P, or 10 P to 6,000 P, inclusive, as determined using a Brookfield viscometer. Conditions for the dynamic viscosity test include use of a LV4 spindle at a speed of 0.3 or 0.6 revolutions per minute (RPM) at 24 degrees Celsius.
The polymerizable compositions are often in the form of a two-part composition. Hence, in a second aspect, a two-part composition is provided. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol. Stated another way, the two-part composition includes:
(1) a first part comprising a polymeric material comprising:
(2) a second part comprising at least one accelerator.
The uretdione-containing material, first hydroxyl-containing material, optional second hydroxyl-containing material, polythiol, and acidic stabilizer are typically each as described above in detail with respect to the polymeric material of the first aspect.
Optionally, at least one of the first part or the second part comprises one or more additives, e.g., plasticizers, non-reactive diluents, toughening agents, fillers, flow control agents, colorants (e.g., pigments and dyes), adhesion promoters, UV stabilizers, flexibilizers, fire retardants, antistatic materials, thermally and/or electrically conductive particles, and expanding agents. These additives are as described above with respect to the polymeric material of the first aspect.
Preferably, the uretdione-containing material has an average isocyanate functionality of less than 0.1%.
The polymeric material needs to have enough of a uretdione group functionality per molecule of polymeric material to allow for curing of a two-part composition into an effective polymer network when reacted with the polythiol. Typically, the polymeric material comprises an average of 1.3 to 6.0 inclusive, of a uretdione functional group in a backbone of the polymeric material. It is usually advantageous for the first part (e.g., the polymeric material, the first hydroxyl-containing compound, the polythiol, the accelerator, the optional second hydroxyl-containing compound, and the optional epoxy component) to be flowable, (e.g., to allow for mixing with the second part) and to readily wet the surface of either a substrate to be coated or two substrates to be adhered. To provide a uretdione-containing polymeric material that has a relatively low viscosity at a high solids content, the polythiol is included, plus an optional reactive diluent epoxy component may also be included. In published reports, uretdione-containing materials used in solvent-borne coatings have had a molecular weight that is too high be practical in the adhesive systems having 90% or greater solids content without also including a polythiol (or an epoxy component). Further, it has been found that the amount of diol in a first part of a two-part composition can be included in a range of about 0.2 to 0.65 (or 0.25 to 0.61) equivalents relative to the isocyanate equivalents to achieve a suitable viscosity and a sum of the OH equivalents of the first hydroxyl-containing compound and the optional second hydroxyl-containing compound is equal to or greater than the isocyanate equivalents of the polymeric material.
In some embodiments, at least one of the first part or the second part further comprises an accelerator comprising a catalyst. Suitable accelerators (e.g., curatives and catalysts) are also described in detail above with respect to the first part. One or more of these accelerators can be useful in increasing the speed of reaction or catalyzing a reaction of components of the first part with the second part. For instance, the accelerator may be present in the first part and comprise a catalyst for reacting the uretdione-containing material with the first-hydroxyl-containing compound and, if present, with the second hydroxyl-containing compound. Further, the accelerator may be present in at least one of the first part or the second part and comprise a catalyst for reacting with an optional epoxy component.
In some embodiments, the accelerator comprises a nonacidic amine having the formula NR20R21. R20 and R21 independently represent H or a monovalent organic group having from 1 to 18 carbon atoms and may contain hetero atoms such as O and N (e.g., methyl, ethyl, propyl, butyl, isobutyl, ethoxyethyl, pentyl, hexyl, cyclohexyl, phenyl, 2,4-dimethylphenyl, octyl, decyl, hexadecyl, or octadecyl); R22 represents a monovalent organic group having from 2 to 18 carbon atoms and may contain hetero atoms such as O and N (e.g., ethyl, propyl, butyl, isobutyl, ethoxyethyl, pentyl, hexyl, cyclohexyl, phenyl, 2,4-dimethylphenyl, octyl, decyl, hexadecyl, or octadecyl); or R21 and R22 taken together represent a divalent organic group having from 2 to 18 carbon atoms (e.g., ethylene, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, —CH2CH2OCH2CH2—, or 2,2-diphenylpropane-1,3-diyl); or R20, R21, and R22 taken together represent a trivalent organic group having from 2 to 18 carbon atoms (e.g., nonane-1,5,9-triyl and 3-(ethyl-2′-yl)pentan-1,5-diyl).
Examples of suitable accelerators include triethylamine; 1,4-diaza[2.2.2]bicyclooctane (DABCO); aniline; N,N-dimethylaniline; 2,6-dimethylaniline; 1-methylimidazole; pyridine; N,N-dimethyl-4-aminopyridine; benzylamine; dicyclohexylamine; N,N-dicyclohexylmethylamine; 4-methylmorpholine; cyclohexylamine; piperidine; morpholine; 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol; 1-methylpiperidine; quinuclidine; 2,2,6,6-tetramethylpiperidine; 1-methylpyrrolidine; N-benzylmethylamine; 1,2,2,6,6-pentamethylpiperidine; 2-{[2-(dimethylamino)ethyl]methylamino}ethanol; 3-dimethylamino-1-propanol; and 2-[2-(dimethylamino)ethoxy]ethanol.
Examples of suitable accelerators include substituted pyridines having 5 to 23 carbon atoms. Substituted pyridines include chloropyridine, bromopyridine, fluoropyridine, iodopyridine, methylpyridine, ethylpyridine, propylpyridine, tert-butylpyridine, phenylpyridine, methoxypyridine, ethoxypyridine, phenoxypyridine, nitropyridine, dichloropyridine, dibromopyridine, dimethylpyridine, diethylpyridine, di-tert-butylpyridine, methyl nicotinate, ethyl nicotinate, methyl picolinate, ethyl picolinate, methyl isonicotinate, cyanopyridine, and trimethylpyridine.
Commercially available accelerators include a trifunctional amine-terminated polyether available as JEFFAMINE T-403 Polyetheramine and difunctional amine-terminated polyether available as JEFFAMINE THF-100 Polyetheramine, both from Huntsman Corp.; 1,3-benzenedimethanamine, reaction products with epichlorohydrin, available as GASKAMINE 328; and aspartic acid, secondary diamine available as Desmophen NH1220 from Covestro LLC.
In some preferred embodiments, the at least one accelerator is free of substituted or unsubstituted imidazole, amidine, and/or triazole groups.
In some embodiments, the accelerator can be incorporated directly into a uretdione-containing compound by incorporating at least one pendant —CH2NR232 group wherein each R23 independently represents an alkyl group having from 1 to 8 carbon atoms, or two R23 groups taken together form an alkylene group having from 2 to 8 carbon atoms. Such compounds can be formed as described above for reactions of mono-ols with uretdione ring-containing compounds with one of more isocyanate groups, except that a tertiary aminoalcohol is used instead. Advantageously, such reactions may be self-catalyzing due to the tertiary amino group. Exemplary aminoalcohols include N,N-dimethyl-2-amino-1-ethanol, N,N-diethyl-2-amino-1-ethanol, N,N-dimethyl-3-amino-1-propanol, N,N-dimethyl-4-amino-1-butanol, N,N-dimethyl-6-amino-1-hexanol, and N,N-dibutyl-8-amino-1-octanol. In embodiments containing an accelerator incorporated directly into a uretdione-containing compound, that accelerator is present in the second part.
Similarly, in other embodiments the accelerator is incorporated into an epoxy component such that the epoxy component comprises at least one pendant —CH2NR232 group, wherein each R23 independently represents an alkyl group having from 1 to 8 carbon atoms, or two R23 groups taken together form an alkylene group having from 2 to 8 carbon atoms. For example, the accelerator may be incorporated into the epoxy component such that the epoxy component comprises a glycidyl amine, preferably an epoxidized product of meta-xylenediamine, an epoxidized product of methylene dianiline, or an epoxidized product of para-amino phenol. In embodiments containing an accelerator incorporated directly into an epoxy component, that accelerator is present in the second part.
When an amine curative is present (e.g., as the accelerator), polymeric materials according to the present disclosure should be paired with second parts having amine curatives with a functionality that is greater than 2.0, to produce better properties, such as adhesive strength and gel content. Previous reports, for instance, teach that primary amines give a rapid cure of uretdione-containing material that limits pot life, and it has been found that that is the case with certain amines, such as diethylenetriamine and other ethylenediamine oligomers. Interestingly, it has been found that polymeric materials according to the present disclosure cure to a soft, poorly crosslinked material when cured with certain diamines. However, it has also been found that amine-terminated polyethers (e.g., available under the trade name “JEFFAMINE” commercially available from Huntsman (The Woodlands, Tex.)) produce an acceptable rate of cure, particularly when they are primary amines. Trifunctional JEFFAMINE amines, such as JEFFAMINE T403, have been found to produce particularly good performance in adhesive systems according to the present disclosure. Difunctional JEFFAMINE amines, such as JEFFAMINE D230, D400, AND THF-100, have also been found to produce good performance in adhesive systems according to the present disclosure. Extremely high molecular weight amines tend to not provide good miscibility with the polymeric material of the first part, however, and in some cases the apparent phase separation of the uretdione-containing material and the amine curing agent tends to prevent effective cure. The relatively high molecular weight of JEFFAMINE curing agents provide another advantage over small-molecule diamines: the JEFFAMINES require a weight ratio between the curing agent and the uretdione-containing material that is higher, and a balanced mixture ratio (e.g., the more closely it approaches 50 wt. % of each component) is often more convenient for two-part compositions.
In some embodiments, at least one amine of the optional amine curative (e.g., accelerator) is a primary amine.
The optional amine curative(s) (e.g., accelerator(s)) present in the second part preferably have an average amine functionality of 1.0 or greater, 1.5 or greater, 2.0 or greater, 2.1 or greater, 2.2 or greater, 2.3 or greater, 2.4 or greater, 2.5 or greater, 2.6 or greater, 2.7 or greater, 2.8 or greater, 2.9 or greater, 3.0 or greater, 3.1 or greater, 3.2 or greater, 3.3 or greater, 3.4 or greater, or even 3.5 or greater; and an average amine functionality of 4.0 or less. The average amine functionality of 2.0 or greater tends to result in more desirable properties of the polymerized product after curing with the amine curing agent, such as gel content and adhesive strength. Moreover, the average amine functionality may be selected based on whether a desired application requires, e.g., stiffness versus elasticity; or high Tg versus low Tg. The “average amine functionality” is the average number of amine nitrogen atoms per molecule.
In certain embodiments, the second part includes a diamine or a triamine, (e.g., as the accelerator) such as a difunctional amine-terminated polyether or a trifunctional amine-terminated polyether, respectively. Another suitable amine curative for use in the second part comprises a phenalkamine, 4,7,10-trioxatridecane-1,13-diamine and/or a reaction product of epichlorohydrin with 1,3-benzenedimethanamine. For instance, a reaction product of epichlorohydrin with 1,3-benzenedimethanamine is commercially available under the trade designation GASKAMINE 328 from Mitsubishi Gas Chemical Company (New York, N.Y.). Exemplary amines include for instance, solvent-free phenalkamine available under the trade designation CARDOLITE 5607 from Cardolite Corporation (Monmouth Junction, N.J.) and a reactive liquid polyamide available under the trade designation ANCAMIDE 350A from Evonik Industries (Essen, Germany).
The optional amine curative (e.g., accelerator) often comprises a molecular weight of 2,000 grams per mole (g/mole) or less, 1,800 g/mole or less, 1,600 g/mole or less, 1,500 g/mole or less, 1,400 g/mole or less, 1,200 g/mole or less, or even 1,000 g/mole or less.
In some embodiments, the second part also contains a polythiol having an average sulfhydryl group functionality of 2 or greater. Suitable polythiols are as described in detail above with respect to the polymeric material. The optional polythiol may be present in an amount of 0% by weight to 98% by weight, based on the total weight of the second part.
Preferably, the second part exhibits a viscosity of 0.1 Poise (P) to 10,000 P, inclusive, 0.1 Poise (P) to 5,000 P, inclusive, or 0.1 Poise (P) to 1,000 P, inclusive, as determined using a Brookfield viscometer.
It has been discovered that it is possible to provide two-part compositions (according to at least certain embodiments of the present disclosure) that are 90% or greater solids and exhibit each of 1) good flowability; 2) acceptable extent of cure; and 3) curing in a relatively short amount of time. Adhesive two-part compositions can further exhibit 4) acceptable adhesion strength following curing. In certain embodiments, the first part and the second part are each flowable at 20° C.
The uretdione-containing material is typically kept separate from the accelerator (e.g., curing agent) prior to use of the polymerizable composition. That is, the uretdione-containing material is typically in a first part and the accelerator is typically in a second part of the polymerizable composition. The first part can include other components that do not react with the uretdione-containing material (or that react with only a portion of the uretdione-containing material). Likewise, the second part can include other components that do not react with the accelerator or that react with only a portion of the accelerator. Advantageously, the presence of the polythiol reduces the viscosity of the polymeric material. Moreover, two-part systems according to the present disclosure are less dependent on having an optimized mix ratio than other two-part systems because the polythiol curative and the uretdione-containing material are pre-mixed in the first part.
Without the presence of an acidic stabilizer in the polymeric material, however, the polythiol would react enough with the uretdione-containing material to polymerize and form a gelled material too quickly to provide a shelf-stable product, e.g., in less than four days in some cases, as depicted for instance in the general reaction Scheme 3A below. In contrast, when an acidic stabilizer is present in a polymeric material, the polymeric material has a longer shelf life.
Then when the first part and the second part are mixed together, the various components react to form the reaction product, for instance as shown below in the general reaction Scheme 3B below:
In a third aspect, a polymerized product is provided. The polymerized product is the polymerized product of any of the two-part compositions according to the second aspect described above. The polymerized product typically coats at least a portion of a substrate, and up to the entire surface of a substrate depending on the application. When the polymerized product acts as an adhesive, often the polymerized product is disposed between two substrates (e.g., adhering the two substrates together). Advantageously, the polymerized product of at least some embodiments of the disclosure is suitable for use when at least one substrate comprises a moisture impermeable material, due to the high solids content of the polymerizable composition. Hence, in certain embodiments at least one substrate is made of a metal (e.g., steel), a glass, a wood, a ceramic, or a polymeric material. The polymerized product may also be employed with one or more substrates that have moisture permeability, for instance but without limitation, woven materials, nonwoven materials, paper, foams, membranes, and polymeric films.
In a fourth aspect, a method of adhering two substrates is provided. Referring to
Referring again to
Stated another way, a method of adhering two substrates together comprises:
Depending on the particular application, an amount of each of the first part and the second part obtained will vary; in certain embodiments, an excess of one or both of the first part and the second part is obtained and hence only a portion of one or both of the first part and the second part, respectively, will be combined to form a mixture. In other embodiments, however, a suitable amount of each of the first part and the second part for adhering the first and second substrates together is obtained and essentially all of the first part and the second part is combined to form the mixture. In certain embodiments, combining a (e.g., predetermined) amount of the first part with a (e.g., predetermined) amount of the second part is performed separately from the first and second substrates, while in other embodiments the combining is performed (e.g., directly) on the first major surface of a substrate.
The mixture is typically applied to (e.g., disposed on) the surface of the substrate using conventional techniques such as, for example, dispensing, bar coating, roll coating, curtain coating, rotogravure coating, knife coating, spray coating, spin coating, or dip coating techniques. Coating techniques such as bar coating, roll coating, and knife coating are often used to control the thickness of a layer of the mixture. In certain embodiments, the disposing comprises spreading the mixture on the first major surface of the first substrate, for instance when the mixture is dispensed (e.g., with a nozzle, etc.) on the surface of the substrate such that the mixture does not cover the entirety of a desired area.
Referring to
Advantageously, the two-part compositions according to at least certain embodiments of the present disclosure are capable of providing at least a minimum adhesion of two substrates together. Following cure, the adhesive preferably exhibits a minimum overlap shear on aluminum of 0.3 megaPascals (MPa), 1 MPa, 5 MPa, 10 MPa, 25 MPa, or 50 MPa. A suitable test for determining the minimum overlap shear is described in the Examples below.
In a fifth aspect, a method of curing a two-part composition is provided. The method includes (a) obtaining a two-part composition; (b) combining at least a portion of the first part with at least a portion of the second part to form a mixture; and (c) disposing the mixture on a first major surface of a substrate. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
Stated another way, a method of curing a two-part composition comprises:
Optionally, the mixture is disposed on a first major surface of a substrate prior to step (c) including heating the mixture. The mixture may be allowed to cure for the times described above with respect to the fourth aspect.
The components of the first part are as described above with respect to the first aspect and the second part is as described above with respect to the second aspect. Typically, at least one accelerator (e.g., catalyst) is present in the first part, in the second part, or in each of the first part and the second part. Suitable accelerators are described in detail above with respect to the first part.
Embodiment 1 is a polymeric material. The polymeric material includes a polymerized reaction product of a polymerizable composition including components, a polythiol having an average sulfhydryl group functionality of 2 or greater, and an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (a) a uretdione-containing material including a reaction product of a diisocyanate reacted with itself, (b) a first hydroxyl-containing compound having more than one OH group; and (c) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
Embodiment 2 is the polymeric material of embodiment 1, wherein components (a), (b), and, if present, (c), are reacted, and then at least one of the polythiol and the acidic stabilizer is combined with the reaction product of components (a), (b), and, if present, (c).
Embodiment 3 is the polymeric material of embodiment 1 or embodiment 2, wherein the acidic stabilizer is selected from the group consisting of BF3, C1-C16 monocarboxylic acids, C1-C16 dicarboxylic acids, C6-C14 arylcarboxylic acids, C1-C16 monosulfonic acids, C1-C16 disulfonic acids, C6-C14 arylsulfonic acids, C1-C16 monophosphonic acids, C1-C16 diphosphonic acids, C6-C14 arylphosphonic acids, and combinations thereof.
Embodiment 4 is the polymeric material of any of embodiments 1 to 3, wherein the polythiol has an average sulfhydryl group functionality of 2.5 or greater, 3 or greater, or 4 or greater.
Embodiment 5 is the polymeric material of any of embodiments 1 to 4, further including an accelerator including a catalyst.
Embodiment 6 is the polymeric material of embodiment 5, wherein the accelerator includes a catalyst for reacting the uretdione-containing material with the first-hydroxyl-containing compound and, if present, with the second hydroxyl-containing compound.
Embodiment 7 is the polymeric material of embodiment 6, wherein the catalyst includes a bismuth carboxylate.
Embodiment 8 is the polymeric material of embodiment 7, wherein the bismuth carboxylate is bismuth neodecanoate or bismuth ethylhexanoate.
Embodiment 9 is the polymeric material of any of embodiments 1 to 8, further including an epoxy component.
Embodiment 10 is the polymeric material of embodiment 9, wherein the epoxy component is present in an amount of 2 to 80% by weight, 5 to 70% or 10 to 60% by weight, based on the total weight of the polymeric material.
Embodiment 11 is the polymeric material of embodiment 9 or embodiment 10, further including an accelerator including a catalyst for reacting with the epoxy component.
Embodiment 12 is the polymeric material of embodiment 11, wherein the catalyst includes a Lewis acid salt.
Embodiment 13 is the polymeric material of embodiment 12, wherein the Lewis acid salt includes calcium triflate, calcium nitrate, or lanthanum nitrate.
Embodiment 14 is the polymeric material of any of embodiments 1 to 13, wherein the uretdione-containing material is present in an amount of 10% by weight or greater, based on the total weight of the polymeric material, 20% by weight or greater, 30% by weight or greater, 40% by weight or greater, or 50% by weight or greater, based on the total weight of the polymeric material.
Embodiment 15 is the polymeric material of any of embodiments 1 to 14, wherein the polythiol is present in an amount of 5 to 50% by weight, based on the total weight of the polymeric material.
Embodiment 16 is the polymeric material of any of embodiments 1 to 15, wherein the polythiol includes a primary thiol.
Embodiment 17 is the polymeric material of any of embodiments 1 to 16, wherein the polythiol includes a secondary thiol.
Embodiment 18 is the polymeric material of any of embodiments 1 to 15, wherein the polymeric material is in the form of a liquid.
Embodiment 19 is a two-part composition. The two-part composition includes (1) a first part comprising a polymeric material and (2) a second part comprising at least one accelerator. The polymeric material includes (a) a polymerized reaction product of a polymerizable composition including components; (b) a polythiol having an average sulfhydryl group functionality of 2 or greater; and (c) an acidic stabilizer. The polymeric material has an average uretdione ring functionality of at least 1.2 and the polymeric material comprises a solids content of 90% or greater. The components include (i) a uretdione-containing material comprising a reaction product of a diisocyanate reacted with itself, (ii) a first hydroxyl-containing compound having more than one OH group; and (iii) an optional second hydroxyl-containing compound having a single OH group. The second hydroxyl-containing compound is a primary alcohol or a secondary alcohol.
Embodiment 20 is the two-part composition of embodiment 19, wherein the accelerator includes an amine curative.
Embodiment 21 is the two-part composition of embodiment 19 or embodiment 20, wherein the accelerator includes a nonacidic amine curative comprising pyridine, a substituted pyridine having 5 to 23 carbon atoms, or an amine having the formula NR20R21R22 wherein:
Embodiment 22 is the two-part composition of embodiment 21, wherein the amine curative does not include a substituted or unsubstituted amidine group.
Embodiment 23 is the two-part composition of embodiment 19 or embodiment 20, wherein the accelerator is incorporated into the uretdione-containing material such that the uretdione-containing material includes at least one pendant —CH2NR232 group, wherein each R23 independently represents an alkyl group having from 1 to 8 carbon atoms, or two R23 groups taken together form an alkylene group having from 2 to 8 carbon atoms.
Embodiment 24 is the two-part composition of any of embodiments 19 to 23, wherein the second part further includes a polythiol having an average sulfhydryl group functionality of 2 or greater.
Embodiment 25 is the two-part composition of any of embodiments 19 to 24, wherein the acidic stabilizer is present in the first part in an amount of 0.01 to 1% by weight, based on the total weight of the polymeric material.
Embodiment 26 is the two-part composition of any of embodiments 19 to 25, wherein the acidic stabilizer is selected from the group consisting of BF3, C1-C16 monocarboxylic acids, C1-C16 dicarboxylic acids, C6-C14 arylcarboxylic acids, C1-C16 monosulfonic acids, C1-C16 disulfonic acids, C6-C14 arylsulfonic acids, C1-C16 monophosphonic acids, C1-C16 diphosphonic acids, C6-C14 arylphosphonic acids, and combinations thereof.
Embodiment 27 is the two-part composition of any of embodiments 19 to 26, wherein at least one of the first part or the second part further includes an accelerator comprising a catalyst.
Embodiment 28 is the two-part composition of embodiment 27, wherein the accelerator is present in the first part and includes a catalyst for reacting the uretdione-containing material with the first-hydroxyl-containing compound and, if present, with the second hydroxyl-containing compound.
Embodiment 29 is the two-part composition of embodiment 28, wherein the catalyst includes a bismuth carboxylate, preferably bismuth neodecanoate or bismuth ethylhexanoate.
Embodiment 30 is the two-part composition of any of embodiments 19 to 29, wherein the uretdione-containing material is present in an amount of 10% by weight or greater, based on the total weight of the polymeric material, 20% by weight or greater, 30% by weight or greater, 40% by weight or greater, or 50% by weight or greater, based on the total weight of the polymeric material.
Embodiment 31 is the two-part composition of any of embodiments 19 to 30, wherein the second hydroxyl-containing compound is present and is an alkyl alcohol, a polyester alcohol, or a polyether alcohol.
Embodiment 32 is the two-part composition of any of embodiments 19 to 31, wherein the first hydroxyl-containing compound is an alkylene polyol, a polyester polyol, or a polyether polyol.
Embodiment 33 is the two-part composition of any of embodiments 19 to 32, wherein the uretdione-containing material comprises a compound of Formula I:
wherein R1 is independently a C4 to C14 alkylene, arylene, and alkaralyene.
Embodiment 34 is the two-part composition of any of embodiments 19 to 33, wherein the second hydroxyl-containing compound is present and is of Formula VII:
R13—OH VII;
wherein R13 is selected from R14, R15, and a C1 to C50 alkyl;
wherein R14 is of Formula VIII:
wherein m=1 to 20, R16 is an alkyl, and R17 is an alkylene;
wherein R15 is of Formula IX:
wherein n=1 to 20, R18 is an alkyl, and R19 is an alkylene.
Embodiment 35 is the two-part composition of any of embodiments 19 to 34, wherein the first hydroxyl-containing compound is of Formula II:
HO—R2—OH II;
wherein R2 is selected from R3, an alkylene, and an alkylene substituted with an OH group, wherein R3 is of Formula III or Formula IV:
wherein each of R4, R5, R6, R7, and R8 is independently an alkylene, wherein each of v and y is independently 1 to 40, and wherein x is selected from 0 to 40.
Embodiment 36 is the two-part composition of embodiment 35, wherein R2 is selected from a C1 to C20 alkylene and a C1 to C20 alkylene substituted with an OH group.
Embodiment 37 is the two-part composition of embodiment 35 or embodiment 34, wherein each of R4, R5, R6, R7, and R8 is independently a C1 to C20 alkylene.
Embodiment 38 is the two-part composition of any of embodiments 19 to 34, wherein the first hydroxyl-containing compound is of Formula V or Formula VI:
wherein each of R9 and R11 is independently an alkane-triyl, wherein each of R10 and R12 is independently an alkylene and wherein each of w and z is independently 1 to 20.
Embodiment 39 is the two-part composition of embodiment 38, wherein each of R10 and R12 is independently a C1 to C20 alkylene.
Embodiment 40 is the two-part composition of any of embodiments 19 to 39, including an average of 1.3 to 6.0, inclusive, or 1.5 to 4.0, inclusive, of a uretdione functional group in a backbone of the polymeric material.
Embodiment 41 is the two-part composition of any of embodiments 19 to 40, wherein the first part has a solids content of 94% or greater or 98% or greater.
Embodiment 42 is the two-part composition of any of embodiments 19 to 41, including an average of 0.2 to 18, inclusive, of a carbamate functional group in a backbone of the polymeric material.
Embodiment 43 is the two-part composition of any of embodiments 19 to 42, wherein the polymeric material is essentially free of isocyanates.
Embodiment 44 is the two-part composition of any of embodiments 19 to 43, wherein the polymeric material includes an average of 1.3 or fewer isocyanurate units per molecule of the polymeric material.
Embodiment 45 is the two-part composition of any of embodiments 19 to 44, wherein the diisocyanate includes hexamethylene diisocyanate.
Embodiment 46 is the two-part composition of any of embodiments 19 to 44, wherein the diisocyanate includes a functional group selected from Formula X, Formula XI, and Formula XII.
Embodiment 47 is the two-part composition of any of embodiments 19 to 46, wherein the first part includes a dynamic viscosity of 10 Poise (P) to 30,000 P, inclusive, 10 P to 10,000 P, inclusive, or 10 P to 6,000 P, inclusive, as determined using a Brookfield viscometer.
Embodiment 48 is the two-part composition of any of embodiments 19 to 47, wherein the first part further includes a plasticizer, a non-reactive diluent, or a combination thereof.
Embodiment 49 is the two-part composition of any of embodiments 19 to 48, wherein the first part further includes an epoxy component.
Embodiment 50 is the two-part composition of embodiment 49, wherein the epoxy component is present in an amount of 2 to 80% by weight, 5 to 70% by weight, or 10 to 60% by weight, based on the total weight of the polymeric material.
Embodiment 51 is the two-part composition of embodiment 49 or embodiment 50, wherein at least one of the first part or the second part further includes an accelerator including a catalyst for reacting with the epoxy component.
Embodiment 52 is the two-part composition of embodiment 51, wherein the catalyst includes a Lewis acid salt.
Embodiment 53 is the two-part composition of embodiment 52, wherein the Lewis acid salt includes calcium triflate, calcium nitrate, or lanthanum nitrate.
Embodiment 54 is the two-part composition of any of embodiments 49 to 53, wherein the epoxy component includes at least one multifunctional epoxy.
Embodiment 55 is the two-part composition of any of embodiments 49 to 54, wherein the epoxy component includes at least one trifunctional epoxy.
Embodiment 56 is the two-part composition of any of embodiments 49 to 55, wherein the epoxy component includes at least one glycidyl ether group.
Embodiment 57 is the two-part composition of any of embodiments 49 to 56, wherein the epoxy component has a molecular weight of 2,000 grams per mole or less.
Embodiment 58 is the two-part composition of any of embodiments 49 to 57, wherein the epoxy component exhibits a dynamic viscosity of 100,000 centipoises (cP) or less, 50,000 cP or less, or 20,000 cP or less, as determined using a Brookfield viscometer.
Embodiment 59 is the two-part composition of any of embodiments 49 to 58, wherein the epoxy component includes an aliphatic epoxy.
Embodiment 60 is the two-part composition of any of embodiments 49 to 59, wherein the accelerator is incorporated into an epoxy component such that the epoxy component comprises at least one pendant —CH2NR232 group, wherein each R23 independently represents an alkyl group having from 1 to 8 carbon atoms, or two R23 groups taken together form an alkylene group having from 2 to 8 carbon atoms, and the accelerator is present in the second part.
Embodiment 61 is the two-part composition of any of embodiments 49 to 59, wherein the accelerator is incorporated into an epoxy component such that the epoxy component comprises a glycidyl amine, preferably an epoxidized product of meta-xylenediamine, an epoxidized product of methylene dianiline, or an epoxidized product of para-amino phenol, and the accelerator is present in the second part.
Embodiment 62 is the two-part composition of any of embodiments 19 to 61, wherein at least one of the first part or the second part further includes at least one additive selected from a toughening agent, a filler, a flow control agent, an adhesion promoter, a colorant, a UV stabilizer, a flexibilizer, a fire retardant, an antistatic material, a thermally and/or electrically conductive particle, or an expanding agent.
Embodiment 63 is the two-part composition of any of embodiments 19 to 62, wherein the second hydroxyl-containing compound is present and is selected from 2-butanol, 2-ethyl-1-hexanol, isobutanol, and 2-butyl-octanol.
Embodiment 64 is the two-part composition of any of embodiments 19 to 58, wherein the first hydroxyl-containing compound is selected from 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol, poly(tetramethylene ether) glycol, 2-ethylhexane-1,3-diol, and 1,3-butanediol.
Embodiment 65 is the two-part composition of any of embodiments 19 to 37 or 40 to 64, wherein the second hydroxyl-containing compound is present and is of Formula VII and the first hydroxyl-containing compound is of Formula II, wherein R2 of the compound of Formula II is of Formula III, and wherein R13 of the compound of Formula VII is a branched C4 to C20 alkyl.
Embodiment 66 is the two-part composition of any of embodiments 19 to 65, wherein a sum of the OH equivalents of the first hydroxyl-containing compound and the second hydroxyl-containing compound is equal to or greater than the isocyanate equivalents of the polymeric material.
Embodiment 67 is the two-part composition of any of embodiments 19 to 66, wherein the first hydroxyl-containing compound is a diol and the reaction product comprises 0.2 to 0.65, inclusive, or 0.25 to 0.61, inclusive, of diol equivalents relative to isocyanate equivalents.
Embodiment 68 is the two-part composition of any of embodiments 19 to 67, wherein the first hydroxyl-containing compound includes a branched diol.
Embodiment 69 is the two-part composition of any of embodiments 19 to 68, wherein the second hydroxyl-containing compound is present and includes a branched alcohol.
Embodiment 70 is the two-part composition of any of embodiments 19 to 69, wherein the second hydroxyl-containing compound is present and includes a secondary alcohol.
Embodiment 71 is the two-part composition of any of embodiments 19 to 70, wherein the curative includes an amine curative and at least one molecule of the amine curative has an average amine functionality of 4.0 or less.
Embodiment 72 is the two-part composition of any of embodiments 19 to 71, wherein the curative includes an amine curative and the amine curative has an average amine functionality of 2.4 or greater.
Embodiment 73 is the two-part composition of any of embodiments 19 to 72, wherein the curative includes an amine curative and the amine curative includes a primary amine comprising a phenalkamine, 4,7,10-trioxatridecane-1,13-diamine, a reaction product of epichlorohydrin with 1,3-benzenedimethanamine, or combinations thereof.
Embodiment 74 is the two-part composition of any of embodiments 19 to 73, wherein the curative includes an amine curative and the amine curative includes a triamine.
Embodiment 75 is the two-part composition of any of embodiments 19 to 74, wherein the curative includes an amine curative and the amine curative includes an amine-terminated polyether.
Embodiment 76 is the two-part composition of any of embodiments 19 to 75, wherein the curative includes an amine curative and the amine curative includes a difunctional or trifunctional amine-terminated polyether.
Embodiment 77 is the two-part composition of any of embodiments 19 to 76, wherein the curative includes an amine curative and the amine curative includes a reaction product of epichlorohydrin with 1,3-benzenedimethanamine.
Embodiment 78 is the two-part composition of any of embodiments 19 to 77, wherein the curative includes an amine curative and the amine curative includes a molecular weight of 2,000 grams per mole or less.
Embodiment 79 is the two-part composition of any of embodiments 19 to 78, wherein the second part has a solids content of 90% or greater, 94% or greater, or 98% or greater.
Embodiment 80 is the two-part composition of any of embodiments 19 to 79, wherein the second part exhibits a viscosity of 0.1 Poise (P) to 5,000 P, inclusive, or 0.1 Poise (P) to 1,000 P, inclusive, as determined using a Brookfield viscometer.
Embodiment 81 is the two-part composition of any of embodiments 19 to 80, wherein the polythiol in the first part has an average sulfhydryl group functionality of 2.5 or greater, 3 or greater, or 4 or greater.
Embodiment 82 is the two-part composition of any of embodiments 19 to 81, wherein the polythiol is present in the first part in an amount of 5 to 50% by weight, based on the total weight of the polymeric material.
Embodiment 83 is the two-part composition of any of embodiments 19 to 82, wherein the polythiol includes a primary thiol.
Embodiment 84 is the two-part composition of any of embodiments 19 to 83, wherein the polythiol includes a secondary thiol.
Embodiment 85 is the two-part composition of any of embodiments 19 to 84, wherein the first part is in the form of a liquid.
Embodiment 86 is a polymerized product. The polymerized product is of the two-part composition of any of embodiments 19 to 85.
Embodiment 87 is the polymerized product of embodiment 86, wherein the polymerized product coats at least a portion of a substrate.
Embodiment 88 is the polymerized product of embodiment 86 or embodiment 87, wherein the polymerized product is disposed between two substrates.
Embodiment 89 is the polymerized product of embodiment 87 or embodiment 88, wherein at least one substrate includes a moisture impermeable material.
Embodiment 90 is the polymerized product of any of embodiments 87 to 89, wherein at least one substrate is made of a metal.
Embodiment 91 is a method of adhering two substrates together. The method includes (a) obtaining the two-part composition of any of embodiments 19 to 85; (b) combining at least a portion of the first part with at least a portion of the second part to form a mixture; (c) disposing at least a portion of the mixture on a first major surface of a first substrate; and (d) contacting a first major surface of a second substrate with the mixture disposed on the first substrate.
Embodiment 92 is the method of embodiment 91, further including securing the first substrate to the second substrate and allowing the mixture to cure to form an adhesive adhering the first substrate and the second substrate together.
Embodiment 93 is the method of embodiment 91 or embodiment 92, further including allowing the mixture to cure for at least 12 hours at ambient temperature to form an adhesive adhering the first substrate and the second substrate together.
Embodiment 94 is the method of any of embodiments 91 to 93, wherein the adhesive exhibits a minimum overlap shear on aluminum of 0.3 megaPascals (MPa).
Embodiment 95 is the method of any of embodiments 91 to 94, where the combining is performed on the first major surface of the first substrate.
Embodiment 96 is the method of any of embodiments 91 to 95, wherein the disposing includes spreading the mixture on the first major surface of the first substrate.
Embodiment 97 is a method of curing a two-part composition. The method includes (a) obtaining the two-part composition of any of embodiments 19 to 85; (b) combining at least a portion of the first part with at least a portion of the second part to form a mixture; and (c) disposing the mixture on a first major surface of a substrate.
Embodiment 98 is the method of embodiment 97, further including allowing the mixture to cure for at least 12 hours at ambient temperature.
Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Table 1, below, lists materials used in the examples and their sources.
Test Methods
Overlap Shear Test Method
The performance of adhesives derived from uretdione polymeric material was determined using overlap shear tests. Aluminum coupons (25 millimeter (mm)×102 mm×1.6 mm) were sanded with 220 grit sandpaper and wiped with isopropanol and dried. The uretdione polymeric material, acid and the thiol curative were each added to a plastic cup and mixed at 2700-3500 revolutions per minute (RPM) for 45 seconds to 90 seconds using a speed mixer (DAC 150 FV SpeedMixer from FlackTek, Landrum, S.C.). Accelerator was then added, and the mixture was mixed at 2700-3500 RPM for 15 to 30 seconds using a combination of hand mixing with a wood applicator stick and the speed mixer.
The mixture was then applied to a 25 mm×13 mm area on one end of the aluminum coupon, and two pieces of stainless steel wire (0.25 mm diameter) were placed in the resin to act as bondline spacers. One end of a second aluminum coupon was then pressed into to the mixture to produce an overlap of approximately 13 mm. A binder clip was placed on the sample, and it was allowed to cure for at least 18 hours. The samples were tested to failure in shear mode at a rate of 2.54 mm/minute using a tensile load frame with self-tightening grips (MTS Systems, Eden Prairie, Minn.). After failure, the length of the overlap area was measured. The overlap shear value was then calculated by dividing the peak load by the overlap area, to result in units of pounds per square inch (psi) or megapascals (MPa), and the average results of two replicates is reported.
Gel Point Determination Test Method
The pot life of uretdione polymeric materials was determined by monitoring the time required to reach a gel. The uretdione polymeric material, polythiol curative, and epoxy (where applicable) were each added to a plastic cup and mixed for 30 seconds using a DAC 150 FV SpeedMixer at 3000 RPM. The mixture was mixed by hand for 10 seconds and then mixed again for 30 seconds using a speed mixer at 3000 RPM. Acid (when applicable) was then added and the mixture was mixed for 30 seconds using a speed mixer at 3000 RPM. The mixture was hand-mixed until the material could not be drawn without breaking, which was determined to be the gel point. Time in hours was calculated from the addition of thiol until the moment gelation occurred.
Uretdione Consumption Test Method
The infrared (IR) spectra of the examples in Table 8 were obtained using an infrared Fourier Transform spectrometer (NICOLET 6700 FT-IR Spectrometer, Thermo Scientific, Madison, Wis.) equipped with a Smart iTR Diamond Attenuated Total Reflectance (ATR) accessory. The uretdione consumption was determined by monitoring the peak height of the uretdione material over time. The uretdione polymeric material, the polythiol curative and epoxy (where applicable) were each added to a plastic cup and mixed for 30 seconds using a speed mixer (DAC 150 FV SpeedMixer) at 3000 RPM. The mixture was mixed by hand for 10 seconds and then mixed again for 30 seconds using the speed mixer at 3000 RPM. Acid (when applicable) was then added and the mixture was mixed for 30 seconds using the speed mixer at 3000 RPM. For all the examples, a strong uretdione signal around 1764 cm−1 (+/−5 cm−1) was observed after mixing. The relative height of the uretdione peak at 1764.09 cm−1 at different time points was measured relative to the initial peak height to determine the consumption of uretdione over time.
FTIR Characterization
The infrared (IR) spectra of the polymeric material samples and the cured adhesives were obtained using an infrared Fourier Transform spectrometer (NICOLET 6700 FT-IR Spectrometer, Thermo Scientific, Madison, Wis.) equipped with a Smart iTR Diamond Attenuated Total Reflectance (ATR) accessory. For all the polymeric materials the isocyanate peak at 2260 cm−1 was not present in the infrared spectrum, indicating that the isocyanate had reacted completely with the alcohols during the preparation of the polymeric materials. For all the polymeric materials, a strong uretdione signal at 1760 cm−1 was observed. For all the cured adhesives, the uretdione signal at 1760 cm−1 had nearly disappeared, indicating reaction of the uretdione group during the cure of the adhesives.
NMR Analysis of DN3400
DN3400 was dissolved in deuterated dimethyl sulfoxide (DMSO) solvent. The 1H proton spectrum was taken with a 500 MHz NMR (AVANCE III 500 MHz spectrometer equipped with a broadband cryoprobe from Bruker, Billerica, Mass.). The resulting spectrum had 5 major signals. Signals at 1.31 parts per million (ppm) and 1.55 ppm were attributed to methylene groups at the 3 and 4 positions and the 2 and 5 positions of the HDI derivatives, respectively. A signal at 3.17 ppm was attributed to methylene protons adjacent to a uretdione group. A signal at 3.34 ppm was attributed to methylene protons adjacent to an isocyanate group. A signal at 3.74 ppm was attributed to methylene protons adjacent to an isocyanurate group. The integrations of these three methylene signals were 1.35, 1.79, and 0.49, respectively. The published values for DN3400 are an equivalent weight of isocyanate of 193 g/equivalent and 22 weight percent isocyanate. The ratio of the integration of the signal at 3.17 ppm over the integration of the signal at 3.34 ppm is 0.75, which corresponds to 16 wt. % uretdione. The ratio of the integration of the signal at 3.74 ppm over the integration of the signal at 3.34 ppm is 0.27, which corresponds to 3 wt. % isocyanurate. The functionality of DN3400 is published as 2.5 (in “Raw Materials for Automotive Refinish Systems” from Bayer Materials Science, 2005), thus the average molecular weight of the molecule in DN3400 is 193 grams/equivalent×2.5 equivalents/mole=482 grams/mol. For every 2.5 isocyanate methylene groups, there are 0.75*2.5=1.875 uretdione methylene groups. There are two methylene groups per uretdione group, so there are about 0.94 uretdione groups per molecule of DN3400.
Calculation of Uretdione Functionality in Polymeric Materials
A modified Carothers equation relates degree of polymerization (DP) to the average functionality (fav) and conversion (p) in a step growth polymerization [Carothers, Wallace (1936). “Polymers and Polyfunctionality”. Transactions of the Faraday Society. 32: 39-49]:
DP=2/(2−(p*fav))
This equation can be used to calculate the average degree of polymerization of each polymeric material. Based on the degree of polymerization, the average number of uretdione groups in the polymeric material (fUD) can be calculated by:
fUD=DP*(DN3400 molecules)*(uretdione groups per DN3400 molecule)/(total molecules)
where the values for “DN3400 molecules” and the “total molecules” correspond to the respective moles of molecules used to make the polymeric material, and the value for “uretdione groups per DN3400 molecule” is 0.94, as calculated based on the NMR data (above). It is shown below that polymeric materials with an average uretdione functionality between 0.94<(fUD)<5 in combination with a diluent produce reasonably good properties when cured.
General Polymeric Material Preparation
Bismuth neodecanoate, DN3400, the chain extender, the capping group, and epoxy (when applicable) were added to a glass jar according to Tables 2, 3, 4 and 5. The amounts of alcohol that were added correspond to the equivalent values in Tables 2, 3, 4 and 5 (relative to the equivalents of isocyanate). The mixture was stirred magnetically at 700 RPM. Initially the mixture was hazy, and after about one minute, the mixture became clear and slightly warm. The mixture then continued to noticeably exotherm. Stirring was continued for a total of 5 minutes, and the polymeric material was then allowed to cool to room temperature. The composition and calculated uretdione functionality of each formulation are reported in Tables 2, 3, 4 and 5.
The mixtures were then tested for overlap shear (OLS), Gel point, and uretdione consumption according to the test methods described above. Overlap shear test results are reported in Table 6 for the various formulations tested. Gel points are reported in Table 7. Uretdione consumptions are reported in Table 8.
Other modifications and variations to the present disclosure may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present disclosure, which is more particularly set forth in the appended claims. It is understood that aspects of the various embodiments may be interchanged in whole or part or combined with other aspects of the various embodiments. All cited references, patents, or patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2019/057777 | 9/16/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62736273 | Sep 2018 | US | |
| 62830765 | Apr 2019 | US |
