Patent Application
20220315818
The present disclosure relates generally to materials used as reinforcing coatings for membranes used in spiral wound filtration assemblies.
Presently, industry is utilizing spiral wound filtration assemblies to process water, food and beverage materials. Adhesives are widely used to assemble the membrane leaf components of these assemblies. In the element rolling process, it is typical for the membrane leaf to be “creased” or “folded” at the permeate water tube, creating a membrane leaf weak point. Details of such assemblies are known and may be found in, for example, U.S. Pat. Nos. 4,842,736 and 7,303,675, the contents of each of which are incorporated by reference in their entirety.
Adhesives have been used as coatings on the folded membrane leaf areas to try and provide the membrane with improved durability at the fold area and to prevent leakage during use. In some applications the membrane assemblies receive daily cleaning with strong chlorine solutions or high temperature (70-85° C.) and high pH (11.0-12.5) solutions. Adhesives used for fold protection must be resistant to these cleaning solutions, high temperature and high pH conditions and maintain their mechanical integrity without cracking or delaminating from the membrane material.
Two types of adhesive are currently used as fold protection materials; one is curable two component polyurethane adhesive and the other is curable acrylate adhesive. Polyurethane possesses good flexibility and resistance to high pH/temperature environments but requires a long cure time (8 hours to days). The long cure time limits polyurethane adhesives to off-line processing in producing folded membrane pack. UV curable acrylate adhesives have been proposed for use as fold protection materials. Some acrylate adhesives are too brittle for this use. More flexible acrylate adhesives are 1) not able to achieve tack-free surface under short UV exposure, and 2) easily lose integrity, adhesion, and peel off the membrane under the required high temperature and pH conditions mentioned above. As a result, neither two component polyurethane adhesive nor acrylate adhesive are optimal as a membrane fold protection material.
From this perspective, there is a need for a high performance fold protection adhesive that is quickly curable and also has good flexibility and resistance to high pH/temperature environments.
One aspect of the disclosure provides a hybrid, two component dual cure adhesive. The adhesive combines two component, reaction cure polyurethane chemistry and UV cure acrylate chemistry. The hybrid adhesive provides a tack-free surface after exposure to short periods of UV radiation and provides reduced shrinkage and increased flexibility. The hybrid adhesive has increased resistance to cleaning solution treatments operated at high temperature and pH. In the adhesive, the proportion of polyurethane and acrylate are adjusted to optimize the UV cure, chemical resistance, and cost.
Another aspect of the disclosure provides a membrane leaf having a hybrid, two component dual cure adhesive applied over the fold area.
Another aspect of the disclosure provides a method of applying a hybrid, two component dual cure adhesive to a membrane fold area.
In general, unless otherwise explicitly stated the disclosed materials and processes may be alternately formulated to comprise, consist of, or consist essentially of, any appropriate components, moieties or steps herein disclosed. The disclosed materials and processes may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants, moieties, species and steps used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objective of the present disclosure.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art. As used herein for each of the various embodiments, the following definitions apply.
The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.
About or “approximately” as used herein in connection with a numerical value refer to the numerical value ±10%, preferably ±5% and more preferably ±1% or less.
At least one, as used herein, means 1 or more, i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, or more. With reference to an ingredient, the indication refers to the type of ingredient and not to the absolute number of molecules. “At least one polymer” thus means, for example, at least one type of polymer, i.e., that one type of polymer or a mixture of several different polymers may be used.
The terms “comprising”, “comprises” and “comprised of” as used herein are synonymous with “including”, “includes”, “containing” or “contains”, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps.
When amounts, concentrations, dimensions and other parameters are expressed in the form of a range, a preferable range, an upper limit value, a lower limit value or preferable upper and limit values, it should be understood that any ranges obtainable by combining any upper limit or preferable value with any lower limit or preferable value are also specifically disclosed, irrespective of whether the obtained ranges are clearly mentioned in the context.
Preferred and preferably are used frequently herein to refer to embodiments of the disclosure that may afford particular benefits, under certain circumstances. However, the recitation of one or more preferable or preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude those other embodiments from the scope of the disclosure.
A one component or one part (1K) composition is a singular formulation that has sufficient commercial stability to be prepared, warehoused and shipped to an end user. The 1K composition can be used without adding any additional components and will crosslink or cure when exposed to suitable conditions. As used herein a two component or two part (2K) composition has two or more components. Each of the components is prepared, warehoused and shipped separately from the other components. The components are mixed immediately prior to use. Mixing of the components starts a cure reaction so commercial storage after mixing is not possible.
Unless indicated otherwise, all percentages that are cited in connection with the compositions described herein refer to weight percent (wt. %) with respect to final composition of all components for a one part (1K) composition or with respect to final composition of all components in the referenced part for a two part (2K) composition.
Alkyl refers to a monovalent group that contains carbon atoms and hydrogen atoms, for example 1 to 8 carbons atoms, that is a radical of an alkane and includes linear and branched configurations. Examples of alkyl groups include, but are not limited to: methyl; ethyl; propyl; isopropyl; n-butyl; isobutyl; sec-butyl; Cert-butyl; n-pentyl; n-hexyl; n-heptyl; and, 2-ethylhexyl. In the present invention, such alkyl groups may be unsubstituted or may optionally be substituted. Preferred substituents include one or more groups selected from halo, nitro, cyano, amido, amino, sulfonyl, sulfinyl, sulfanyl, sulfoxy, urea, thiourea, sulfamoyl, sulfamide and hydroxy. The halogenated derivatives of the exemplary hydrocarbon radicals listed above might, in particular, be mentioned as examples of suitable substituted alkyl groups. Preferred alkyl groups include unsubstituted alkyl groups containing from 1-6 carbon atoms (C1-C6 alkyl)—for example unsubstituted alkyl groups containing from 1 to 4 carbon atoms (C1-C4 alkyl).
Alkylene refers to a divalent group that contains carbon atoms, for example from 1 to 20 carbon atoms, that is a radical of an alkane and includes linear and branched organic groups, which may be unsubstituted or optionally substituted. Preferred alkylene groups include unsubstituted alkylene groups containing from 1-12 carbon atoms (C1-C12 alkylene)—for example unsubstituted alkylene groups containing from 1 to 6 carbon atoms (C1-C6 alkylene) or from 1 to 4 carbons atoms (C1-C4 alkylene).
Alkenyl group refers to an aliphatic carbon group that contains carbon atoms, for example 2 to 20, advantageously 2 to 10 and more advantageously 2 to 6 carbon atoms and at least one double bond. The alkene can be an allyl group. The alkene can contain one or more double bonds that are conjugated. Like the aforementioned alkyl group, an alkenyl group can be straight, branched or cyclic, and may be unsubstituted or may be optionally substituted. Examples of C2-C8 alkenyl groups include, but are not limited to: allyl; isoprenyl; 2-butenyl; and, 2-hexenyl.
“Alkoxy” refers to the structure —OR, wherein R is hydrocarbyl.
“Alkyne” or “alkynyl” refers to a hydrocarbon chain or group containing one or more triple bonds between the chain carbon atoms. The alkyne can be a straight hydrocarbon chain or a branched hydrocarbon group. The alkyne can be cyclic. The alkyne can contain 1 to 20 carbon atoms, advantageously 1 to 10 carbon atoms and more advantageously 1 to 6 carbon atoms. The alkyne can contain one or more triple bonds that are conjugated. In some embodiments the alkyne can be substituted.
“Amine” refers to a molecule comprising at least one —NHR group wherein R can be a covalent bond, H, hydrocarbyl or polyether. In some embodiments an amine can comprise a plurality of —NHR groups (which may be referred to as a polyamine).
“Aryl” or “Ar” used alone or as part of a larger moiety—as in “aralkyl group”—refers to unsubstituted or optionally substituted, monocyclic, bicyclic and tricyclic ring systems in which the monocyclic ring system is aromatic or at least one of the rings in a bicyclic or tricyclic ring system is aromatic. The bicyclic and tricyclic ring systems include benzofused 2-3 membered carbocyclic rings. Exemplary aryl groups include phenyl; indenyl; naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl; tetrahydroanthracenyl; and, anthracenyl.
Acrylate refers to the univalent —O—C(O)—C═C moiety. Methacrylate refers to the univalent —O—C(O)—C(CH3)═C moiety. (Meth)acrylate refers to acrylate and methacrylate.
Acryloyl (ACR) refers to a —C(O)—C═C moiety. Methacryloyl (MCR) refers to a —C(O)—C(CH3)═C moiety. (Meth)acryloyl refers to acryloyl and methacryloyl.
“Ester” refers to the structure R—C(O)—O—R′ where R and R′ are independently selected hydrocarbyl groups with or without heteroatoms. The hydrocarbyl groups can be substituted or unsubstituted.
“Halogen” or “halide” refers to an atom selected from fluorine, chlorine, bromine and iodine.
“Hetero” refers to one or more heteroatoms in a structure. Exemplary heteroatoms are independently selected from N, O and S. an atom other than carbon or hydrogen, for example nitrogen, oxygen, phosphorus or sulfur. The expression “interrupted by at least one heteroatom” means that the main chain of a residue comprises, as a chain member, at least one heteroatom.
“Heteroaryl” refers to a monocyclic or multicyclic aromatic ring system wherein one or more ring atoms in the structure are heteroatoms. Exemplary heteroatoms are independently selected from N, O and S. The cyclic rings can be linked by a bond or fused. The heteroaryl can contain from 5 to about 30 carbon atoms; advantageously 5 to 12 carbon atoms and in some embodiments 5 to 6 carbon atoms. Exemplary heteroaryls include furyl, imidazolyl, pyrimidinyl, tetrazolyl, thienyl, pyridyl, pyrrolyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, thiazolyl, quinolinyl and isoquinolinyl. In some embodiments the heteroaryl is substituted.
“Hydrocarbyl” refers to a group containing carbon and hydrogen atoms. The hydrocarbyl can be linear, branched, or cyclic group. The hydrocarbyl can be alkyl, alkenyl, alkynyl or aryl. In some embodiments, the hydrocarbyl is substituted.
“Molecular weight” refers to weight average molecular weight unless otherwise specified. The number average molecular weight Mn, as well as the weight average molecular weight Mw, is determined according to the present invention by gel permeation chromatography (GPC, also known as SEC) at 23° C. using a styrene standard. This method is known to one skilled in the art. The polydispersity is derived from the average molecular weights Mw and Mn. It is calculated as PD=Mw/Mn. Polydispersity indicates the width of the molecular weight distribution and thus of the different degrees of polymerization of the individual chains in polydisperse polymers. For many polymers and polycondensates, a polydispersity value of about 2 applies. Strict monodispersity would exist at a value of 1. A low polydispersity of, for example, less than 1.5 indicates a comparatively narrow molecular weight distribution.
“Oligomer” refers to a defined, small number of repeating monomer units such as 2-5,000 units, and advantageously 10-1,000 units which have been polymerized to form a molecule. Oligomers are a subset of the term polymer.
“Polyether” refers to polymers which contain multiple ether groups (each ether group comprising an oxygen atom connected top two hydrocarbyl groups) in the main polymer chain. The repeating unit in the polyether chain can be the same or different. Exemplary polyethers include homopolymers such as polyoxymethylene, polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetrahydrofuran, and copolymers such as poly(ethylene oxide co propylene oxide), and EO tipped polypropylene oxide.
“Polyester” refers to polymers which contain multiple ester linkages. A polyester can be either linear or branched.
“Polymer” refers to any polymerized product greater in chain length and molecular weight than the oligomer. Polymers can have a degree of polymerization of about 20 to about 25000. As used herein polymer includes oligomers and polymers. Polymerization conditions means the reaction conditions suitable to combine monomers into polymers.
“Polyol” refers to a molecule comprising two or more —OH groups. A polyol can further have other functionalities on the molecule. The term “polyol” encompasses a single polyol or a mixture of two or more polyols.
Room temperature refers a temperature of about 22 to 25° C.
“Substituted” refers to the presence of one or more substituents on a molecule in any possible position. Useful substituents are those groups that do not significantly diminish the disclosed reaction schemes. Exemplary substituents include, for example, H, halogen, (meth)acrylate, epoxy, oxetane, urea, urethane, N3, NCS, CN, NCO, NO2, NX1X2, OX1, C(X1)3, C(halogen)3, COOX1, SX1, Si(OX1)iX23−i, alkyl, alcohol, alkoxy; wherein X1 and X2 each independently comprise H, alkyl, alkenyl, alkynyl or aryl and i is an integer from 0 to 3.
“Thiol” refers to a molecule comprising at least one —SH group. In some embodiments a thiol can comprise a plurality of —SH groups (which may be referred to as a polythiol).
The adhesive can include one or more multifunctional polyols. As used herein a multifunctional polyol is a molecule having two or more OH groups and optionally other functional groups. Multifunctional polyol include aromatic polyester and polyether polyols, aliphatic polyester and polyether polyols, polypropylene glycol polyols, castor oil based polyols, polycaprolactone polyols, and polycarbonate polyols from various suppliers such as INVISTA, BASF, Huntsman, Univar, and Bayer. The multifunctional polyol can have a MW of 60 g/mol to 6,000 g/mol. In some embodiments the multifunctional polyol can have a MW of 140 g/mol to 4,000 g/mol.
The multifunctional polyol can comprise a short chain polyol. Short chain polyols have typical MW less than 1000 g/mol and preferably 60 g/mol to 1,000 g/mol. Useful short chain polyols include ethanediol, propanediol, butanediol.
The adhesive can include one or more (meth)acrylate monomers. (Meth)acrylate monomer includes monofunctional (meth)acrylate monomers, multifunctional (meth)acrylate monomers and combinations thereof. The monofunctional (meth)acrylate monomer can be selected from monofunctional alkyl (meth)acrylates, monofunctional alkenyl (meth)acrylates, and monofunctional heterocyclo (meth)acrylates, wherein said alkyl is an alkyl group having from 1 to 20 carbon atoms, which may have one or more substituents; said alkenyl is an alkenyl group having from 2 to 20 carbon atoms, which may have one or more substituents; and said heterocyclo is a heterocyclic group having from 2 to 20 carbon atoms and having a heteroatom selected from nitrogen and oxygen, which may have one or more substituents; said one or more substituents may be selected from an alkyl group having from 1 to 20 carbon atoms, an alkyloxy group having from 1 to 20 carbon atoms, an aryloxy group having from 6 to 20 carbon atoms, a cycloalkyloxy group having from 3 to 20 carbon atoms, and hydroxyl.
The multifunctional (meth)acrylate monomer can be selected from multifunctional alkyl (meth)acrylates, multifunctional alkenyl (meth)acrylates, and multifunctional heterocyclo (meth)acrylates, wherein said alkyl is an alkyl group having from 1 to 20 carbon atoms, which may have one or more substituents; said alkenyl is an alkenyl group having from 2 to 20 carbon atoms, which may have one or more substituents; and said heterocyclo is a heterocyclic group having from 2 to 20 carbon atoms and having a heteroatom selected from nitrogen and oxygen, which may have one or more substituents; said one or more substituents may be selected from an alkyl group having from 1 to 20 carbon atoms, an alkyloxy group having from 1 to 20 carbon atoms, an aryloxy group having from 6 to 20 carbon atoms, a cycloalkyloxy group having from 3 to 20 carbon atoms, and hydroxyl.
Representative examples of the (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-(2-ethoxyethoxy) ethyl acrylate, tetrahydrofurfuryl (meth)acrylate, lauryl acrylate, isooctyl acrylate, isodecyl acrylate, 2-phenoxyethyl acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, caprolactone acrylate, morpholine (meth)acrylate, hexanediol di(meth)acrylate, ethyleneglycol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate and combinations thereof.
The adhesive can include one or more (meth)acrylate monomers that include di- or tri-functional (meth)acrylates like polyethylene glycol di(meth)acrylates, tetrahydrofuran (meth)acrylates and di(meth)acrylates, hydroxypropyl (meth)acrylate, hexanediol di(meth)acrylate, trimethylol propane tri(meth)acrylate (“TMPTMA”), diethylene glycol dimethacrylate, triethylene glycol dimethacrylate (“TRIEGMA”), benzylmethacrylate, tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, di-(pentamethylene glycol) dimethacrylate, tetraethylene diglycol diacrylate, diglycerol tetramethacrylate, tetramethylene dimethacrylate, ethylene dimethacrylate, neopentyl glycol diacrylate, trimethylol propane triacrylate and bisphenol-A mono and di(meth)acrylates, such as ethoxylated bisphenol-A (meth)acrylate (“EBIPMA”), bisphenol-F mono and di(meth)acrylates, such as ethoxylated bisphenol-F (meth)acrylate.
The adhesive can include one or more (meth)acrylate-functionalized urethanes. Useful (meth)acrylate functionalized urethanes include tetramethylene glycol urethane acrylate oligomer and a propylene glycol urethane acrylate oligomer. Other (meth)acrylate-functionalized urethanes are urethane (meth)acrylate oligomers based on polyethers or polyesters, which are reacted with aromatic, aliphatic, or cycloaliphatic diisocyanates and capped with hydroxy acrylates. Some useful examples include difunctional urethane acrylate oligomers, such as a polyester of hexanedioic acid and diethylene glycol, terminated with isophorone diisocyanate, capped with 2-hydroxyethyl acrylate (CAS 72121-94-9); a polypropylene glycol terminated with tolyene-2,6-diisocyanate, capped with 2-hydroxyethylacrylate (CAS 37302-70-8); a polyester of hexanedioic acid and diethylene glycol, terminated with 4,4′-methylenebis(cyclohexyl isocyanate), capped with 2-hydroxyethyl acrylate (CAS 69011-33-2); a polyester of hexanedioic acid, 1,2-ethanediol, and 1,2 propanediol, terminated with tolylene-2,4-diisocyanate, capped with 2-hydroxyethyl acrylate (CAS 69011-31-0); a polyester of hexanedioic acid, 1,2-ethanediol, and 1,2 propanediol, terminated with 4,4′-methylenebis(cyclohexyl isocyanate, capped with 2-hydroxyethyl acrylate (CAS 69011-32-1); and a polytetramethylene glycol ether terminated with 4,4′-methylenebis(cyclohexylisocyanate), capped with 2-hydroxyethyl acrylate. Still other (meth)acrylate-functionalized urethanes are monofunctional urethane acrylate oligomers, such as a polypropylene terminated with 4,4′-methylenebis(cyclohexylisocyanate), capped with 2-hydroxyethyl acrylate and 1-dodosanol.
(Meth)acrylate-functionalized urethanes also include difunctional urethane methacrylate oligomers such as a polytetramethylene glycol ether terminated with tolulene-2,4-diisocyanate, capped with 2-hydroxyethyl methacrylate; a polytetramethylene glycol ether terminated with isophorone diisocyanate, capped with 2-hydroxyethyl methacrylate; a polytetramethylene glycol ether terminated with 4,4′-methylenebis(cyclohexylisocyanate), capped with 2-hydroxyethyl methacrylate; and a polypropylene glycol terminated with tolylene-2,4-diisocyanate, capped with 2-hydroxyethyl methacrylate.
The adhesive can include one polyisocyanate or a mixture of different polyisocyanates. Polyisocyanate includes a compound which has at least two reactive isocyanate (—NCO) groups. The polyisocyanate does not have to be a polymer and can be a low molecular compound or monomer.
The polyisocyanates suitable for preparing the polyurethane according to the invention include ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,4-tetramethoxybutane diisocyanate, 1,6-hexamethylene diisocyanate (HDI), cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, bis(2-isocyanatoethyl)fumarate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 2,4- and 2,6-hexahydrotoluylene diisocyanate, hexahydro-1,3- or -1,4-phenylene diisocyanate, benzidine diisocyanate, naphthalene-1,5-diisocyanate, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), 1,3- and 1,4-phenylene diisocyanate, 2,4- or 2,6-toluylene diisocyanate (TDI), 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, or 4,4′-diphenylmethane diisocyanate (MDI), and the isomeric mixtures thereof. Also suitable are partially or completely hydrogenated cycloalkyl derivatives of MDI, for example completely hydrogenated MDI (H12-MDI), alkyl-substituted diphenylmethane diisocyanates, for example mono-, di-, tri-, or tetraalkyldiphenylmethane diisocyanate and the partially or completely hydrogenated cycloalkyl derivatives thereof, 4,4′-diisocyanatophenylperfluorethane, phthalic acid-bis-isocyanatoethyl ester, 1 chloromethylphenyl-2,4- or -2,6-diisocyanate, 1-bromomethylphenyl-2,4- or -2,6-diisocyanate, 3,3′-bis-chloromethyl ether-4,4′-diphenyl diisocyanate, sulfur-containing diisocyanates such as those obtainable by reacting 2 moles diisocyanate with 1 mole thiodiglycol or dihydroxydihexyl sulfide, diisocyanates of dimer fatty acids, or mixtures of two or more of the named diisocyanates.
Other useful polyisocyanates include modified forms of polyisocyanate monomers. Examples of useful modified polyisocyanates include, for example, carbodiimide-modified diphenylmethane diisocyanate (carbodiimide-modified MDI), allophanate-modified diphenylmethane diisocyanate (allophanate-modified MDI), biuret-modified diphenylmethane diisocyanate (biuret-modified MDI), polymeric diphenylmethane diisocyanate (polymeric MDI), and combinations thereof. The preparation of modified polyisocyanates are generally known and the modified polyisocyanates can be prepared by known methods and/or are commercially available.
Other useful polyisocyanates include polyisocyanates with a functionality of three or more obtainable, for example, by oligomerization of diisocyanates, more particularly by oligomerization of the isocyanates mentioned above. Examples of such tri- and higher isocyanates are the triisocyanurates of HDI or IPDI or mixtures thereof or mixed triisocyanurates thereof and polyphenyl methylene polyisocyanate obtainable by phosgenation of aniline/formaldehyde condensates.
The adhesive can optionally include one or more linking components. A linking component is a tie molecule that can react with both the acrylate moieties and the isocyanate moieties present in the mixed adhesive components. Useful linking components include hydroxyl containing (meth)acrylates, amine containing (meth)acrylates, isocyanate containing (meth)acrylates. The adhesive can include one or more hydroxyl containing (meth)acrylates. These components can form, for example, acrylate-acrylate bonds as well as isocyanate-hydroxyl bonds.
Hydroxyl containing (meth)acrylate includes (meth)acrylate compounds having one or more reactive hydroxyl (OH) moieties. Some useful hydroxyl containing (meth)acrylates include, for example, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, N-Hydroxyethyl acrylamide, hydroxybutyl acrylate, hydroxypolyethoxy (10) allyl ether, 3-phenoxy 2 hydroxy propyl methacrylate, glycerol monomethacrylate and mixtures thereof.
Amine containing (meth)acrylate includes (meth)acrylate compounds having one or more reactive amine (NH or NH2) moieties. Some useful amine containing (meth)acrylates include, for example, 2-aminoethyl methacrylate, 2-diisopropylaminoethyl methacrylate, N-(3-aminopropyl)methacrylamide and 2-(N,N-dimethylamino)ethyl acrylate.
Isocyanate containing (meth)acrylate includes (meth)acrylate compounds having one or more reactive isocyanate (NCO) moieties and one or more (meth)acrylate moieties. Some useful isocyanate containing (meth)acrylates include isocyanate bearing -polyester urethane (meth)acrylates, -polyether urethane (meth)acrylates, -aliphatic urethane (meth)acrylates, -aromatic urethane (meth)acrylates available from suppliers such as Sartomer and Allnex.
The adhesive can include one or more photoinitiators. Photoinitiators enhance the rapidity of the curing process when the mixed adhesive composition is exposed to electromagnetic radiation, such as actinic radiation, for example ultraviolet (UV) radiation. Examples of some useful photoinitiators include, but are not limited to, photoinitiators available commercially from Ciba Specialty Chemicals, under the “IRGACURE” and “DAROCUR” trade names, specifically “IRGACURE” 184 (1-hydroxycyclohexyl phenyl ketone), 907 (2-methyl-1[4-(methylthio)phenyl]-2-morpholino propan-1-one), 369 (2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone), 500 (the combination of 1-hydroxy cyclohexyl phenyl ketone and benzophenone), 651 (2,2-dimethoxy-2-phenyl acetophenone), 1700 (the combination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethyl pentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one), and 819 [bis(2,4,6-trimethyl benzoyl) phenyl phosphine oxide] and “DAROCUR” 1173 (2-hydroxy-2-methyl-1-phenyl-1-propan-1-one) and 4265 (the combination of 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one); and the visible light [blue] photoinitiators, dl-camphorquinone and “IRGACURE” 784DC. Of course, combinations of these materials may also be employed herein.
Other photoinitiators useful herein include alkyl pyruvates, such as methyl, ethyl, propyl, and butyl pyruvates, and aryl pyruvates, such as phenyl, benzyl, and appropriately substituted derivatives thereof. Photoinitiators particularly well-suited for use herein include ultraviolet photoinitiators, such as 2,2-dimethoxy-2-phenyl acetophenone (e.g., “IRGACURE” 651), and 2-hydroxy-2-methyl-1-phenyl-1-propane (e.g., “DAROCUR” 1173), bis(2,4,6-trimethyl benzoyl) phenyl phosphine oxide (e.g., “IRGACURE” 819), and the ultraviolet/visible photoinitiator combination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (e.g., “IRGACURE” 1700), as well as the visible photoinitiator bis (5-2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium (e.g., “IRGACURE” 784DC). Useful actinic radiation includes ultraviolet light, visible light, and combinations thereof.
Other photoinitiators useful herein include polymeric photoinitiators. Typically, these photoinitiators have molecular weight between 600-1000 g/mol and are often referred to as oligomeric or polymeric photoinitiators. Preferably molecular weights above 1000 g/mol are considered as not toxicologically relevant. Polymeric photoinitiators include polymeric benzophenone derivatives, polymeric thioxanthone derivatives, and aminobenzoate derivatives available from suppliers such as RAHN. GENOPOL*TX-2 is a multifunctional thioxanthone derivative designed for the use in UV-curable coatings and adhesives, where low migration and low odor is required. GENOPOL*AB-2 is a multifunctional aminobenzoate derivative designed for the use in UV-curable adhesives where low migration and low odor are required. GENOPOL*AB-2 can be used as replacement for standard aminobenzoates and is insoluble in water.
Desirably, the actinic radiation used to cure the photocurable elastomeric sealant composition has a wavelength from about 200 nm to about 1,000 nm. Useful UV includes, but is not limited to, UVA (about 320 nm to about 410 nm), UVB (about 290 nm to about 320 nm), UVC (about 220 nm to about 290 nm) and combinations thereof. Useful visible light includes, but is not limited to, blue light, green light, and combinations thereof. Such useful visible lights have a wavelength from about 450 nm to about 550 nm.
The adhesive can include one or more catalysts. Catalyst includes a catalyst or cure-inducing component to modify speed of the reaction when the two components are mixed. Some suitable catalysts are those conventionally used in polyurethane reactions and polyurethane curing, including organometallic catalysts, organotin catalysts, bismuth catalysts, zirconium catalysts, titanate catalysts, and amine catalysts. Exemplary catalysts include (1,4-diazabicyclo[2.2.2]octane) DABCO® T-12 or DABCO® crystalline, available from Evonik; DMDEE (2,2′-dimorpholinildiethylether); DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). The curable composition can optionally include more than one catalyst.
The adhesive can optionally include one or more additives. The additives can be contained in either or both of the components. Some useful additives include filler, thixotrope, rheology modifier, antioxidant, reaction modifier, thermoplastic polymer, adhesion promoter, coloring agent, tackifier, plasticizer, flame retardant, diluent, reactive diluent, moisture scavenger and combinations thereof.
The curable composition can optionally include filler. Some useful fillers include, for example, lithopone, zirconium silicate, hydroxides, such as hydroxides of calcium, aluminum, magnesium, iron and the like, diatomaceous earth, carbonates, such as sodium, potassium, calcium, and magnesium carbonates, oxides, such as zinc, magnesium, chromic, cerium, zirconium and aluminum oxides, calcium clay, nanosilica, fumed silicas, silicas that have been surface treated with a silane or silazane such as the AEROSIL® products available from Evonik Industries, silicas that have been surface treated with an acrylate or methacrylate such as AEROSIL® R7200 or R711 available from Evonik Industries, precipitated silicas, untreated silicas, graphite, synthetic fibers and mixtures thereof. When used, filler can be employed in concentrations effective to provide desired properties in the uncured composition and cured reaction products and typically in concentrations of about 0% to about 90% by weight of composition, more typically 1% to 30% by weight of composition of filler. Suitable fillers include organoclays such as, for example, Cloisite® nanoclay sold by Southern Clay Products and exfoliated graphite such as, for example, xGnP® graphene nanoplatelets sold by XG Sciences. In some embodiments, enhanced barrier properties are achieved with suitable fillers.
The curable composition can optionally include a thixotrope or rheology modifier. The thixotropic agent can modify rheological properties of the uncured composition. Some useful thixotropic agents include, for example, silicas, such as fused or fumed silicas, that may be untreated or treated so as to alter the chemical nature of their surface. Virtually any reinforcing fused, precipitated silica, fumed silica or surface treated silica may be used. Examples of treated fumed silicas include polydimethylsiloxane-treated silicas, hexamethyldisilazane-treated silicas and other silazane or silane treated silicas. Such treated silicas are commercially available, such as from Cabot Corporation under the tradename CAB-O-SIL® ND-TS and Evonik Industries under the tradename AEROSIL®, such as AEROSIL® R805. Also useful are the silicas that have been surface treated with an acrylate or methacrylate such as AEROSIL® R7200 or R711 available from Evonik Industries. Examples of untreated silicas include commercially available amorphous silicas such as AEROSIL® 300, AEROSIL® 200 and AEROSIL® 130. Commercially available hydrous silicas include NIPSIL® E150 and NIPSIL® E200A manufactured by Japan Silica Kogya Inc. The rheology modifier can be employed in concentrations effective to provide desired physical properties in the uncured composition and cured reaction products and typically in concentrations of about 0% to about 70% by weight of the composition and advantageously in concentrations of about 0% to about 20% by weight of the composition. In certain embodiments the filler and the rheology modifier can be the same.
The curable composition can optionally include an antioxidant. Some useful antioxidants include those available commercially from BASF under the tradename IRGANOX®. When used, the antioxidant should be present in the range of about 0 to about 15 weight percent of curable composition, such as about 0.3 to about 1 weight percent of curable composition.
The curable composition can optionally include a reaction modifier. A reaction modifier is a material that will increase or decrease reaction rate of the curable composition. For example, 8-hydroxyquinoline (8-HQ) and derivatives thereof such as 5-hydroxymethyl-8-hydroxyquinoline can be used to adjust the cure speed. When used, the reaction modifier can be used in the range of about 0.001 to about 15 weight percent of curable composition.
The curable composition can optionally contain a thermoplastic polymer. The thermoplastic polymer may be either a functional or a non-functional thermoplastic. Non-limiting examples of suitable thermoplastic polymers include acrylic polymer, functional (e.g. containing reactive moieties such as —OH and/or —COOH) acrylic polymer, non-functional acrylic polymer, acrylic block copolymer, acrylic polymer having tertiary-alkyl amide functionality, polysiloxane polymer, polystyrene copolymer, divinylbenzene copolymer, polyetheramide, polyvinyl acetal, polyvinyl butyral, polyvinyl chloride, methylene polyvinyl ether, cellulose acetate, styrene acrylonitrile, amorphous polyolefin, olefin block copolymer [OBC], polyolefin plastomer, thermoplastic urethane, polyacrylonitrile, ethylene acrylate copolymer, ethylene acrylate terpolymer, ethylene butadiene copolymer and/or block copolymer, styrene butadiene block copolymer, and mixtures of any of the above.
The curable composition can optionally include one or more adhesion promoters that are compatible and known in the art. Examples of useful commercially available adhesion promoters include amino silane, glycidyl silane, mercapto silane, isocyanato silane, vinyl silane, (meth)acrylate silane, and alkyl silane. Common adhesion promoters are available from Momentive under the trade name Silquest or from Wacker Chemie under the trade name Geniosil. Silane terminated oligomers and polymers can also be used. The adhesion promoter can be used in the range of about 0% to about 20% percent by weight of curable composition and advantageously in the range of about 0.1% to about 15% percent by weight of curable composition.
The curable composition can optionally include one or more coloring agents. For some applications a colored composition can be beneficial to allow for inspection of the applied composition. A coloring agent, for example a pigment or dye, can be used to provide a desired color beneficial to the intended application. Exemplary coloring agents include titanium dioxide, C.I. Pigment Blue 28, C.I. Pigment Yellow 53 and phthalocyanine blue BN. In some applications a fluorescent dye can be added to allow inspection of the applied composition under UV radiation. The coloring agent will be present in amounts sufficient to allow observation or detection, for example about 0.002% or more by weight of total composition. The maximum amount is governed by considerations of cost, absorption of radiation and interference with cure of the composition. More desirably, the coloring agent may be present in amounts of up to about 20% by weight of total composition.
The curable composition can optionally include from about 0% to about 20% by weight, for example about 1% to about 20% by weight of composition of other additives known in the arts, such as tackifier, plasticizer, flame retardant, diluent, reactive diluent, moisture scavenger, and combinations of any of the above, to produce desired functional characteristics, providing they do not significantly interfere with the desired properties of the curable composition or cured reaction products of the curable composition.
When used as an adhesive, the curable compositions can optionally include up to 80% by weight of the total weight of the curable composition of a suitable solvent. This type of adhesives is known as solvent-based adhesives. Upon application of the curable composition on a first substrate, the solvent is quickly evaporated away, for example by heated ovens, then a second substrate is laminated onto the curable composition coated side of the first substrate to form a laminated structure. In other embodiments the curable composition is substantially free or free of solvent and/or water.
With reference to
Membrane 12 is cut from a roll of material to a desired size. As shown in
The applied mixture of curable composition 26 is exposed to actinic radiation, typically in the ultraviolet (UV) wavelength, to initiate a first cure. The mixed polyurethane components will subsequently cure by reaction of the polyol and polyisocyanate materials.
With reference to
The filtration assembly 30 is placed in a housing (not shown). A feed stream 36 is provided to the housing under pressure. The feed stream 36 is comprised of at least two constituents. An illustrative example of the feed stream would be salt water. The feed spacer 22 directs the feed stream 36 longitudinally across the filtration assembly in contact with the filtration surface 18 of the thin, dense semi-permeable layer 13 or filtration layer 14. Water with none or a lower concentration of salt goes through the membranes 10 in a generally perpendicular direction from filtration surface 18 toward the support surface 20 in the filtration assembly forming a permeate stream 38 directed through the porous permeate carrier layer 34 (not shown) into the permeate tube 32. The permeate stream 38 is discharged from the permeate tube 32. The remainder of the feed stream 36, now having a higher concentration of salt than it started with, forms a concentrate stream 42 that is directed out of the filtration assembly 30 separately from the permeate stream 38.
In the Table below the components of some embodiments of the presently disclosed adhesive composition are presented. The amounts are the percentage by weight of that component based on the total adhesive weight.
The components are combined into two components. One component comprises the polyisocyanate and the other component comprises the polyols, hydroxyl containing (meth)acrylate and polyurethane catalyst. The remaining materials may be placed in either component as desired to maintain commercial stability. The two components are stored separately to prevent reaction. Shortly before use the components are mixed to substantial homogeneity to initiate a reaction between the polyisocyanate and hydroxyl containing materials. During reaction the mixture will increase in viscosity and the mixed material cannot be stored and must be used quickly before the mixture cures to an unacceptably high viscosity. In some embodiments the mixed components will have an unacceptably high viscosity in about one hour.
The following examples are included for purposes of illustration so that the disclosure may be more readily understood and are in no way intended to limit the scope of the disclosure unless otherwise specifically indicated.
The components in the following Table were utilized in the examples.
Adhesive components were made using the materials and amounts in the following Table.
Examples 4A, 4B, 5A and 5B were made by mixing the materials in the following Tables together in the absence of moisture.
1castor oil
2Multranol 4012
Comparative samples A and B are commercially available, single component UV-curable acrylic adhesives. Comparative sample C is a commercially available 2-component polyurethane.
The samples were tested for curing, tackiness, bend adhesion and chemical resistance. The membrane used was DOW NF-245 3″×3″and a coating of the sample material was applied to a surface of the membrane at a thickness of about 0.2-0.3 mm and cured.
UV curing was tested by exposing a sample to UV light having a wavelength of 405 nm for 10 seconds at 1.61 W/cm2. After curing sample surface was tested for tackiness by feel, e.g. when the sample no longer felt tacky or sticky to a light touch of a finger to the surface.
Reactive curing for the 3K mix was tested by mixing the two components at 30:70, 50:50, and 70:30 acrylic:polyurethane weight % (wt %) ratio and holding for 24 hours at room temperature. Reactive curing for the integrated hybrid system was tested at a 1:1 volume mix ratio with an overall polyurethane content of 55 wt % and 24 wt % in samples 4 and 5, respectively. Samples were held for 24 hours at room temperature. After curing sample surface was tested for tackiness by feel, e.g. when the sample no longer felt tacky or sticky to a light touch of a finger to the surface.
Bend adhesion was tested by a bend test. The test involves coating one surface of a membrane with a test composition and curing the composition. The coated membrane is folded a first time so that the cured coating is internal to the bend, returned to the flat starting position and folded a second time so that the cured coating is external to the bend. Samples were considered pass if no cracks or delamination of the cured coating from the membrane was observed.
Chemical resistance was tested using an immersion test. Samples were were immersed in a 12.5 pH aqueous solution which was then placed in an 80° C. temperature-controlled oven. The samples were checked periodically for degradation or delamination and the results recorded.
Results of the testing are shown in the Table below.
Both samples A and B can be cured under UV conditions and give good tack-free films on filter membranes in less than 10 seconds.
Samples 1, 2, and 3 are each three component (3K) adhesives comprising a UV-curable component and two, separate polyurethane components. The three components are stored separately and mixed just before use to initiate curing of the polyurethane components. The polyurethane content of each sample decreases from 70 wt. % to 30 wt. %. Due to the increased PU content in samples 1 and 2 the surface remained tacky for a few hours after initial UV-cure, this is not desirable.
Sample 4 and 5 are each an integrated, polyurethane-acrylate, dual cure, two component hybrid system which comprises a primary UV-cure free radical reaction with a secondary polyurethane reaction. Tack-free surfaces was achieved after exposure to UV-light even with a PU content greater than 50 wt % (sample 4).
Samples 4 and 5 are 2K adhesives that are more convenient to use than the 3K mixes of samples 1, 2 and 3. Further, both components of samples 4 and 5 are stable during commercial storage conditions for 6 months or more with no separation of materials in the component.
All samples passed the fold/crease test where the membrane was bent along the surface coating, keeping the coating on the outer face. Similarly, all samples passed the fold/crease test where the membrane was bent along the surface coating, keeping the coating on the inner face. No cracks or coating adhesion failure was observed for any sample in either test.
Membrane samples, each coated on one surface with cured reaction products of one of the samples, were immersed in a 12.5 pH aqueous solution and placed in an 80° C. temperature-controlled oven. After 3 days sample A lost adhesion and began to peel from the membrane. This would be a failure in use. Sample B completely dissolved in the solution. This would be a failure in use. Slight degradation was observed in sample 3 which contained 70 wt % acrylic adhesive. This would be undesirable in use. Samples C, 1, 2, 4 and 5 did not exhibit any loss of adhesion or dissolution and maintained film integrity.
Membrane samples, each coated on one surface with cured reaction products of one of the samples, were immersed in a 12.5 pH aqueous solution and placed in an 80° C. temperature-controlled oven for 10 days. After 10 days sample A (100% acrylic) lost all adhesion however; the film did not dissolve in the solution. This would be a failure in use. After 10 days sample 2 (50 wt. % acrylic and 50 wt. % polyurethane) and sample 3 (70 wt. % acrylic and 30 wt. % polyurethane) either lost all adhesion or began to show significant signs of degradation and detachment. This would be a failure in use. After 10 days sample 1 (30 wt. % acrylic and 70 wt. % polyurethane) with the highest PU wt % began to show an onset of adhesion failure and degradation. This would be a failure in use. After 10 days sample 3 (100% polyurethane) did not exhibit any loss of adhesion or dissolution and maintained film integrity. However, the slow cure speed of sample 3 and the extended tacky period limit that adhesives usefulness in many applications.
After 10 days samples 4 and 5 did not exhibit any loss of adhesion or dissolution and maintained film integrity. Samples 4 and 5 were tack free after the UV exposure period. Thus, samples 4 and 5 comprising an integrated polyurethane-acrylate dual cure hybrid system possess the cure speed of a light cure acrylic without the tacky cure state of polyurethane adhesives while having the chemical resistance of polyurethane adhesives without the loss of adhesion and dissolution problems of acrylic adhesives.
The proceeding description is meant to be exemplary and it is to be understood that variations and modifications may be employed without departing from the concept and intent of the invention as defined in the following claims.
| Number | Date | Country | |
|---|---|---|---|
| 62949588 | Dec 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2020/059953 | Nov 2020 | US |
| Child | 17842905 | US |
