Patent Application
20190112449
The present invention provides a process for producing a molded polymeric article using a polymerizable composition comprising a fluoride-containing mold release agent. The process is particularly useful for production of optical articles using re-usable glass molds.
The use of various thermosetting organic polymeric compositions are known in the art for use in the production of molded polymeric articles. When such molded polymeric articles include polymeric optical articles, the compositions must provide optical articles having acceptable optical qualities while maintaining durability and impact resistance. Examples of such molded polymeric optical articles can include windshields, sunglasses, fashion lenses, non-prescription and prescription lenses, sport masks, face shields, and goggles.
A number of organic polymeric materials, such as plastics, have been developed as alternatives and replacements for glass in applications, such as optical lenses, fiber optics, windows and automotive, nautical and aviation transparencies. These polymeric materials can provide advantages relative to glass, including shatter resistance, lighter weight for a given application, ease of molding and demolding, and ease of dyeing or imparting a color or tint. However, the refractive indices of many polymeric materials are lower than that of glass. In ophthalmic applications, the use of a polymeric material having a lower refractive index will require a thicker lens, which is generally undesirable, relative to a material having a higher refractive index.
Generally, the aforementioned polymeric articles are prepared by casting the polymeric composition in glass molds. It has been found that many of the recently developed polymeric compositions used for this purpose can have an undesirable adhesion to the interior of the glass molds during the casting process. This leads to surface defects of the final polymeric article, as well as an increase in time to prepare and condition the molds with external mold release agents.
Thus, there is a need in the art to develop a polymeric composition having an adequate refractive index, good impact resistance/strength for practical use in optical articles, and ease of demolding from glass molds such that the final article is of acceptable optical quality.
The present invention is directed to a process for producing a molded polymeric article comprising:
(a) providing an organic polymerizable composition comprising a reaction mixture of at least the following components:
(b) allowing the reaction mixture to undergo exothermic reaction;
(c) providing a mold having a first part and a second part spaced one from the other thereby forming a cavity there between;
(d) introducing the reaction mixture of (b) into the mold cavity wherein the reaction mixture is at a temperature of up to 130° C.;
(e) holding the mold of (d) at a temperature and for a time sufficient to cure the reaction mixture thereby forming a molded polymeric article within the mold; and
(f) removing the molded polymeric article from the mold.
Also provided is a process for producing a molded polymeric article comprising:
(a) providing an organic polymerizable composition comprising a reaction mixture of the following components:
(b) optionally, degassing the reaction mixture;
(c) providing a mold having a first part and a second part spaced one from the other thereby forming a cavity there between;
(d) introducing the reaction mixture into the mold cavity;
(e) subjecting the filled mold of (d) to a thermal cure cycle to cure the reaction mixture within the mold to form a molded polymeric article within the mold; and
(f) removing the molded polymeric article from the mold.
Molded polymeric articles are also provided.
It is noted that, as used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents, unless expressly and unequivocally limited to one referent.
For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and other parameters used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
All numerical ranges herein include all numerical values and ranges of all numerical values within the recited numerical ranges. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
The various embodiments and examples of the present invention as presented herein are each understood to be non-limiting with respect to the scope of the invention.
As used herein, a “monovalent hydrocarbon group” means a monovalent group having a backbone repeat unit based exclusively on carbon. As used herein, “monovalent” refers to a substituent group that, as a substituent group, forms only one single covalent bond. For example, a monovalent group on the at least one polysiloxane will form one single covalent bond to a silicon atom in the backbone of the at least one polysiloxane polymer. As used herein, “hydrocarbon groups” are intended to encompass both branched and unbranched hydrocarbon groups.
Thus, when referring to a “monovalent hydrocarbon group”, the hydrocarbon group can be branched or unbranched, acyclic or cyclic, saturated or unsaturated, or aromatic, and can contain from 1 to 24 (or in the case of an aromatic group from 3 to 24) carbon atoms. Non-limiting examples of such hydrocarbon groups include alkyl, alkoxy, alkylene, oxyalkylene, aryl, alkaryl, alkylene aryl, alkenylene, and alkoxyaryl groups. Non-limiting examples of lower alkyl groups include, for example, methyl, ethyl, propyl, and butyl groups. As used herein, “lower alkyl” refers to alkyl groups having from 1 to 6 carbon atoms. One or more of the hydrogen atoms of the hydrocarbon group can be substituted with heteroatoms. As used herein, “heteroatoms” mean elements other than carbon, for example, oxygen, nitrogen, and halogen atoms.
As used herein, “alkylene” refers to an acyclic or cyclic, saturated hydrocarbon group having a carbon chain length of from C2 to C25. Non-limiting examples of suitable alkylene groups include, but are not limited to, those derived from propenyl, 1-butenyl, 1-pentenyl, 1-decenyl, and 1-heneicosenyl, such as, for example (CH2)3, (CH2)4, (CH2)5, (CH2)10, and (CH2)23, respectively, as well as isoprene and myrcene.
As used herein, “oxyalkylene” refers to an alkylene group containing at least one oxygen atom bonded to, and interposed between, two carbon atoms and having an alkylene carbon chain length of from C2 to C25. Non-limiting examples of suitable oxyalkylene groups include those derived from trimethylolpropane monoallyl ether, trimethylolpropane diallyl ether, pentaerythritol monoallyl ether, polyethoxylated allyl alcohol, and polypropoxylated allyl alcohol, such as —(CH2)3OCH2C(CH2OH)2(CH2CH2—).
As used herein, “alkylene aryl” refers to an acyclic alkylene group substituted with at least one aryl group, for example, phenyl, and having an alkylene carbon chain length of C2 to C25. The aryl group can be further substituted, if desired. Non-limiting examples of suitable substituent groups for the aryl group include, but are not limited to, hydroxyl groups, benzyl groups, carboxylic acid groups, and aliphatic hydrocarbon groups. Non-limiting examples of suitable alkylene aryl groups include, but are not limited to, those derived from styrene and 3-isopropenyl-∝,∝-dimethylbenzyl isocyanate, such as —(CH2)2C6H4— and —CH2CH(CH3)C6H3(C(CH3)2(NCO).
As used herein, “alkenylene” refers to an acyclic or cyclic hydrocarbon group having one or more double bonds and having an alkenylene carbon chain length of C2 to C25.
As previously mentioned, the present invention is directed to an organic polymerizable composition for producing a molded polymeric article. The composition comprises a mold release agent comprised of ionic fluoride and/or ionic fluoride precursor which is present in an amount sufficient to effect at least partial demolding of the polymeric article from a mold.
The “ionic fluoride” generally is in the form of a fluoride-containing salt. Suitable, non-limiting examples of such fluoride-containing salts can include ammonium fluoride, potassium fluoride, cesium fluoride, tin (II) fluoride, sodium tetrafluoroborate, tetrabutyl ammonium fluoride (trihydrate), and mixtures thereof.
As used herein, “ionic fluoride precursor” means a material capable of forming ionic fluoride in situ, i.e., (i) upon introduction into the composition or into at least one component of the composition and/or (ii) upon thermal or photochemical induced ionization. Suitable ionic fluoride precursor materials can include, but are not limited to, hexafluorosilicic acid and salts thereof, tris(dimethylamino) sulfonium difluorotrimethylsilicate, boron trifluoride complexes, e.g., 4-methoxysalicyaldehyde*BF3, and mixtures of the foregoing. In general, suitable examples of ionic fluoride precursor materials can include those described in “Greene's Protective Groups in Organic Synthesis”, Wiley Interscience 4th Ed., pages 165-220.
Also, the mold release agent can be selected from the group consisting of boron trifluoride and a fluoride-containing material having the following structure (I):
MRnF(4-n) (I)
where
M represents tin, bismuth, titanium, tantalum, cerium, zirconium, antimony, zinc, aluminum, yttrium, vanadium, or niobium;
each R independently represents a monovalent hydrocarbon group; and
n is an integer ranging from 1 to 3.
Suitable, non-limiting examples of such materials can include nitronium tetrafluoroborate, and tetrafluoroborate salts such as zinc tetrafluoroborate and lithium tetrafluoroborate.
The organic polymerizable composition of the present invention can comprise only ionic fluoride and/or ionic fluoride precursor materials as mold release agents, or the compositions can comprise ionic fluoride and/or ionic fluoride precursor materials along with mold release agents which do not contain ionic fluoride or ionic fluoride precursor materials. The ionic fluoride and/or ionic fluoride precursor materials, along with mold release agents which do not contain ionic fluoride or ionic fluoride precursor materials, can be added (either separately or as an admixture) to the final organic polymerizable composition, or they may be added (either separately or as an admixture) into one or more composition component(s) prior to forming the final polymerizable composition, or they may be added (either separately or as an admixture) to one or more components as well as to the final composition.
In a particular embodiment, in addition to the ionic fluoride and/or ionic fluoride precursor materials, the organic polymerizable composition of the present invention further comprises a mold release agent which does not comprise ionic fluoride or ionic fluoride precursor. Such mold release agents which do not comprise ionic fluoride or ionic fluoride precursor hereinafter are referred to as “co-mold release agent(s)”. Suitable co-mold release agents include, but are not limited to, mono-alkyl phosphates, dialkyl phosphates, organic fatty acids, esters, amines, and mixtures thereof. Specific but non-limiting examples of mono-alkyl and dialkyl phosphates can include those described in EP 0 912 632 B1 at paragraphs [0024] to [0033], which are incorporated herein by reference. Such co-mold release agents can include a mixture of monobutyl acid phosphate and dibutyl acid phosphate commercially available from Kodak and Johoko Chemical Companies, and long chain phosphate esters such as C7 to C18 alkyl phosphates commercially available from Stepan Company as ZELEC® UN. Further examples of such co-mold release agents are those which are blends of organic fatty acids and esters or blends of organic fatty acids, esters and amines commercially available from AXEL Plastics Research Laboratories, Inc. under the product codes INT-1582, INT-1685, and INT-1681/OG.
The ionic fluoride and/or ionic fluoride precursor material should be present in the organic polymerizable composition of the present invention in an amount sufficient to effect at least partial demolding of the polymeric article from a mold, such as a glass mold. That is, the hardened, cured or set molded polymeric article should delaminate sufficiently from the mold surface such that the mold can be reused in subsequent molding processes.
In embodiments where the mold release agent employed in the polymerizable compositions of the present invention comprises only ionic fluoride and/or ionic fluoride precursor materials as the mold release agent, the ionic fluoride mold release agent generally is present in an amount of at least 250 parts per million (ppm), such as 250 to 5000 ppm, or 250 to 1000 ppm, or 250 to 500 ppm. In embodiments where the mold release agent comprises ionic fluoride and/or ionic fluoride precursor materials along with one or more co-mold release agents as described above, the ionic fluoride is present in the composition in an amount ranging from 20 to 5000 ppm, such as 50 to 500 ppm, or 50 to 250 ppm.
In addition to the aforementioned mold release agents (and, where applicable, co-mold release agents), the organic polymerizable composition of the present invention further comprises a polymeric organic material selected from thermosetting polymeric organic materials and thermoplastic polymeric organic materials. The organic polymerizable composition, for example, can comprise a polymeric organic material selected from the group consisting of poly(C1-C12 alkyl methacrylates), poly(oxyalkylene dimethacrylates), poly(alkoxylated phenol methacrylates), cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidene chloride), thermoplastic polycarbonates, polyesters, polyurethanes, polythiourethanes, polysulfithiourethanes, poly(urea-urethane), poly(ethylene terephthalate), polystyrene, poly(alpha methylstyrene), copoly(styrene-methylmethacrylate), copoly(styrene-acrylonitrile), polyvinyl butyral or polymers prepared from bis(allyl carbonate) monomers, polyfunctional acrylate monomers, polyfunctional methacrylate monomers, diethylene glycol dimethacrylate monomers, diisopropenyl benzene monomers, ethoxylated bisphenol A dimethacrylate monomers, ethylene glycol bismethacrylate monomers, poly(ethylene glycol) bismethacrylate monomers, ethoxylated phenol bis methacrylate monomers, alkoxylated polyhydric alcohol polyacrylate monomers, styrene monomers, urethane acrylate monomers, glycidyl acrylate monomers, glycidyl methacrylate monomers, diallylidene pentaerythritol monomers, and mixtures thereof. In a particular embodiment, the organic polymerizable composition of the present invention comprises a polymeric organic material selected from the group consisting of polyurethanes, polythiourethanes, and poly(urea-urethane).
In certain embodiments, the organic polymerizable composition of the present invention comprises, in addition to the mold release agent comprising ionic fluoride and/or ionic fluoride precursor (and, where applicable, any co-mold release agents):
In a further embodiment, the organic polymerizable composition of the present invention comprises, in addition to the mold release agent comprising ionic fluoride and/or ionic fluoride precursor (and, where applicable, any co-mold release agents):
The polyisocyanate component can comprise one or more different polyisocyanates. Polyisocyanates useful in the composition are numerous and widely varied. Non-limiting examples can include aliphatic polyisocyanates, cycloaliphatic polyisocyanates wherein one or more of the isocyanato groups are attached directly to the cycloaliphatic ring, cycloaliphatic polyisocyanates wherein one or more of the isocyanato groups are not attached directly to the cycloaliphatic ring, aromatic polyisocyanates wherein one or more of the isocyanato groups are attached directly to the aromatic ring, and aromatic polyisocyanates wherein one or more of the isocyanato groups are not attached directly to the aromatic ring, and mixtures thereof. When an aromatic polyisocyanate is used, general care should be taken to select a material that does not cause the polyurethane-containing polymer to color (e.g., yellow).
The polyisocyanate can include, but is not limited to, aliphatic or cycloaliphatic diisocyanates, aromatic diisocyanates, cyclic dimers and cyclic trimers thereof, and mixtures thereof. Non-limiting examples of suitable polyisocyanates can include Desmodur N 3300 (hexamethylene diisocyanate trimer) which is commercially available from Bayer; Desmodur N 3400 (60% hexamethylene diisocyanate dimer and 40% hexamethylene diisocyanate trimer). In a non-limiting embodiment, the polyisocyanate can include dicyclohexylmethane diisocyanate and isomeric mixtures thereof. As used herein and the claims, the term “isomeric mixtures” refers to a mixture of the cis-cis, trans-trans, and/or cis-trans isomers of the polyisocyanate. Non-limiting examples of isomeric mixtures for use in the present invention can include the trans-trans isomer of 4,4′-methylenebis(cyclohexyl isocyanate), hereinafter referred to as “PICM” (paraisocyanato cyclohexylmethane), the cis-trans isomer of PICM, the cis-cis isomer of PICM, and mixtures thereof.
Suitable isomers for use in the present invention include, but are not limited to, the following three isomers of 4,4′-methylenebis(cyclohexyl isocyanate), also known as dicyclohexylmethane diisocyanate.
PICM can be prepared by phosgenating 4,4′-methylenebis(cyclohexyl amine) (PACM) by procedures well known in the art, such as the procedures disclosed in U.S. Pat. Nos. 2,644,007; 2,680,127 and 2,908,703; which are incorporated herein by reference. The PACM isomer mixtures, upon phosgenation, can produce PICM in a liquid phase, a partial liquid phase, or a solid phase at room temperature. Alternatively, the PACM isomer mixtures can be obtained by the hydrogenation of methylenedianiline and/or by fractional crystallization of PACM isomer mixtures in the presence of water and alcohols, such as methanol and ethanol.
Additional aliphatic and cycloaliphatic diisocyanates that can be used include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane-4,4′-diisocyanate, 3-isocyanato-methyl-3,5,5-trimethyl cyclohexyl-isocyanate (“IPDI”) which is commercially available from Arco Chemical, m-xylylene diisocyanate (“MXDI”), and meta-tetramethylxylylene diisocyanate (1,3-bis(1-isocyanato-1-methylethyl)-benzene) which is commercially available from Cytec Industries Inc. under the trade name TMXDI® (Meta) Aliphatic Isocyanate.
As used herein, the term “aliphatic and cycloaliphatic diisocyanates” refers to compounds having 6 to 100 carbon atoms linked in a straight chain or cyclized having two isocyanate reactive end groups. In a non-limiting embodiment of the present invention, the aliphatic and cycloaliphatic diisocyanates for use in the present invention can include IPDI and compounds of the formula R—(NCO)2, wherein R represents an aliphatic group or a cycloaliphatic group.
In a particular embodiment of the present invention, the polyisocyanate component comprises isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4′-diisocyanate, meta-tetramethylxylylene diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, and/or meta-xylylene diisocyanate.
The active hydrogen component (b)(ii) used to form the reaction mixture comprises at least one polyol and/or polythiol, and at least one compound containing both amine and hydroxyl functional groups (i.e., an amino alcohol). In certain embodiments the active hydrogen component (b)(ii) used to form the reaction mixture comprises at least two polyols and at least one amino alcohol.
In particular embodiments of the present invention, the reaction mixture is essentially free of compounds containing both amino and aromatic functional groups, wherein the amino groups are attached directly to the aromatic ring. The reaction mixture may also be essentially free of polyamines. Typically, the amino alcohol is aliphatic.
Suitable polyols can include, but are not limited to, polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, and mixtures thereof. Monomeric polyols such as butanediol, 1,6-hexanediol, Bisphenol A and the like, or other higher polyols such as trimethylolpropane, pentaerythritol, and the like, and any of the low molecular weight diols or glycols listed below are also suitable. At least one of the polyols in the active hydrogen component may contain aromatic functionality. It is believed that the use of aromatic polyols increases the refractive index (RI) of the optical article being prepared. However, it is preferred that, when at least one of the polyols is an aromatic ring-containing polyol, the hydroxyl groups in the polyol are not directly bonded to the aromatic ring; i.e., the aromatic polyols are not phenolic.
Examples of polyether polyols are polyalkylene ether polyols which include those having the following structural formula:
where the substituent R1 is hydrogen or lower alkyl containing from 1 to 5 carbon atoms including mixed substituents, and n is typically from 2 to 6 and m is from 8 to 100 or higher. Included are poly(oxytetramethylene) glycols, poly(oxytetraethylene) glycols, poly(oxy-1,2-propylene) glycols, and poly(oxy-1,2-butylene) glycols. Non-limiting examples of alkylene oxides can include ethylene oxide, propylene oxide, butylene oxide, amylene oxide, aralkylene oxides, such as but not limited to styrene oxide, mixtures of ethylene oxide and propylene oxide. In a further non-limiting embodiment, polyoxyalkylene polyols can be prepared with mixtures of alkylene oxide using random or step-wise oxyalkylation.
Also useful are polyether polyols formed from oxyalkylation of various polyols, for example, diols such as ethylene glycol, 1,6-hexanediol, Bisphenol A and the like, or other higher polyols such as trimethylolpropane, pentaerythritol, and the like. Polyols of higher functionality which can be utilized as indicated can be made, for instance, by oxyalkylation of compounds such as sucrose or sorbitol. One commonly utilized oxyalkylation method is reaction of a polyol with an alkylene oxide, for example, propylene or ethylene oxide, in the presence of an acidic or basic catalyst. Particular polyethers include those sold under the names TERATHANE and TERACOL, available from E. I. Du Pont de Nemours and Company, Inc., and POLYMEG, available from Q O Chemicals, Inc., a subsidiary of Great Lakes Chemical Corp.
Polyether glycols for use in the present invention can include, but are not limited to, polytetramethylene ether glycol.
The polyether-containing polyol can comprise block copolymers including blocks of ethylene oxide-propylene oxide and/or ethylene oxide-butylene oxide. Pluronic R, Pluronic L62D, Tetronic R and Tetronic, which are commercially available from BASF, can be used as the polyether-containing polyol material in the present invention.
Suitable polyester glycols can include, but are not limited to, the esterification products of one or more dicarboxylic acids having from four to ten carbon atoms, such as adipic, succinic or sebacic acids, with one or more low molecular weight glycols or diols having from two to ten carbon atoms, such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol and 1,10-decanediol. In a non-limiting embodiment, the polyester glycols can be the esterification products of adipic acid with diols of from two to ten carbon atoms.
Suitable polycaprolactone glycols for use in the present invention can include the reaction products of E-caprolactone with one or more of the low molecular weight glycols listed above. A polycaprolactone may be prepared by condensing caprolactone in the presence of a difunctional active hydrogen compound, such as water, or at least one of the low molecular weight glycols listed above. Particular examples of polycaprolactone glycols include polycaprolactone polyesterdiols available as CAPA® 2047 and CAPA® 2077 from Solvay Corp.
Polycarbonate polyols are known in the art and are commercially available, such as Ravecarb™ 107 (Enichem S.p.A.). In a non-limiting embodiment, the polycarbonate polyol can be produced by reacting an organic glycol such as a diol and a dialkyl carbonate, such as described in U.S. Pat. No. 4,160,853. In a non-limiting embodiment, the polyol can include polyhexamethyl carbonate having varying degrees of polymerization.
The glycol material can comprise low molecular weight polyols, such as polyols having a molecular weight of less than 500, and compatible mixtures thereof. As used herein, the term “compatible” means that the glycols are mutually soluble in each other so as to form a single phase. Non-limiting examples of these polyols can include low molecular weight diols and triols. If used, the amount of triol is chosen so as to avoid a high degree of cross-linking in the polyurethane. A high degree of cross-linking can result in a curable polyurethane that is not formable by moderate heat and pressure. The organic glycol typically contains from 2 to 16, or from 2 to 6, or from 2 to 10 carbon atoms. Non-limiting examples of such glycols and other polyols can include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,2-, 1,3- and 1,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-1,3-pentanediol, 1,3-2,4- and 1,5-pentanediol, 2,5- and 1,6-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-bis(hydroxyethyl)-cyclohexane, glycerin, tetramethylolmethane, such as but not limited to pentaerythritol, trimethylolethane and trimethylolpropane; and isomers thereof.
The polyol can have a weight average molecular weight, for example, of at least 60, or at least 90, or at least 200. Additionally, the polyol can have a weight average molecular weight, for example, of less than 10,000, or less than 7000, or less than 5000, or less than 2000.
The polyol for use in the present invention can include teresters produced from at least one low molecular weight dicarboxylic acid, such as adipic acid.
Polyester glycols and polycaprolactone glycols for use in the present invention can be prepared using known esterification or transesterification procedures as described, for example, in the article D. M. Young, F. Hostettler et al., “Polyesters from Lactone”, Union Carbide F-40, p. 147.
Polyester glycols can also be prepared from the reaction of 1,6-hexanediol and adipic acid; 1,10-decanediol and adipic acid; or 1,10-decanediol and caprolactone.
Thiol-containing materials may be present in the active hydrogen component and may be used to produce a prepolymer such as a sulfur-containing isocyanate-functional polyurethane for the preparation of high index polyurethane-containing films; i.e., films having a relatively high refractive index. Note that, in these embodiments, the polyurethane prepolymer used as the first component may contain disulfide linkages due to disulfide linkages contained in the polythiol and/or polythiol oligomer used to prepare the polyurethane prepolymer.
Thiol-containing materials may have at least two thiol functional groups and may comprise a dithiol, or a mixture of a dithiol and a compound having more than two thiol functional groups (higher polythiol). Such mixtures may include mixtures of dithiols and/or mixtures of higher polythiols. The thiol functional groups are typically terminal groups, though a minor portion (i.e., less than 50 percent of all groups) may be pendant along a chain. The compound (a) may additionally contain a minor portion of other active hydrogen functionality (i.e., different from thiol), for example, hydroxyl functionality. Thiol-containing materials may be linear or branched, and may contain cyclic, alkyl, aryl, aralkyl, or alkaryl groups.
Thiol-containing materials may be selected so as to produce a substantially linear oligomeric polythiol. Therefore, the material comprises a mixture of a dithiol and a compound having more than two thiol functional groups, the compound having more than two thiol functional groups can be present in an amount up to 10 percent by weight of the mixture.
Suitable dithiols can include linear or branched aliphatic, cycloaliphatic, aromatic, heterocyclic, polymeric, oligomeric dithiols, and mixtures thereof. The dithiol can comprise a variety of linkages including, but not limited to, ether linkages (—O—), sulfide linkages (—S—), polysulfide linkages (-Sx-, wherein x is at least 2, or from 2 to 4), and combinations of such linkages.
Non-limiting examples of suitable dithiols for use in the present invention can include, but are not limited to, 2,5-dimercaptomethyl-1,4-dithiane, dimercaptodiethylsulfide (DMDS), ethanedithiol, 3,6-dioxa-1,8-octanedithiol, ethylene glycol di(2-mercaptoacetate), ethylene glycol di(3-mercaptopropionate), poly(ethylene glycol) di(2-mercaptoacetate) and poly(ethylene glycol) di(3-mercaptopropionate), benzenedithiol, 4-tert-butyl-1,2-benzenedithiol, 4,4′-thiodibenzenethiol, and mixtures thereof.
The dithiol may include dithiol oligomers having disulfide linkages, such as materials represented by the following formula:
wherein n can represent an integer from 1 to 21.
Dithiol oligomers represented by Formula IA can be prepared, for example, by the reaction of 2,5-dimeracaptomethyl-1,4-dithiane with sulfur in the presence of basic catalyst, as known in the art.
The nature of the SH group in polythiols is such that oxidative coupling can occur readily, leading to formation of disulfide linkages. Various oxidizing agents can lead to such oxidative coupling. The oxygen in the air can, in some cases, lead to such oxidative coupling during storage of the polythiol. It is believed that a possible mechanism for the oxidative coupling of thiol groups involves the formation of thiyl radicals, followed by coupling of said thiyl radicals, to form disulfide linkage. It is further believed that formation of disulfide linkage can occur under conditions that can lead to the formation of thiyl radical, including but not limited to reaction conditions involving free radical initiation. The polythiols can include species containing disulfide linkages formed during storage.
The polythiols for use in the preparation of the polyurethane material in the first component can also include species containing disulfide linkages formed during synthesis of the polythiol.
In certain embodiments, the dithiol for use in the present invention, can include at least one dithiol represented by the following structural formulas:
The sulfide-containing dithiols comprising 1,3-dithiolane (e.g., formulas II and III) or 1,3-dithiane (e.g., formulas IV and V) can be prepared by reacting asym-dichloroacetone with dimercaptan, and then reacting the reaction product with dimercaptoalkylsulfide, dimercaptan or mixtures thereof, as described in U.S. Pat. No. 7,009,032 B2.
Non-limiting examples of suitable dimercaptans for use in the reaction with asym-dichloroacetone can include, but are not limited to, materials represented by the following formula:
wherein Y can represent CH2 or (CH2—S—CH2), and n can be an integer from 0 to 5. The dimercaptan for reaction with asym-dichloroacetone in the present invention can be chosen from, for example, ethanedithiol, propanedithiol, and mixtures thereof.
The amount of asym-dichloroacetone and dimercaptan suitable for carrying out the above reaction can vary. For example, asym-dichloroacetone and dimercaptan can be present in the reaction mixture in an amount such that the molar ratio of dichloroacetone to dimercaptan can be from 1:1 to 1:10.
Suitable temperatures for reacting asym-dichloroacetone with dimercaptan can vary, often ranging from 0 to 100° C.
Non-limiting examples of suitable dimercaptans for use in the reaction with the reaction product of the asym-dichloroacetone and dimercaptan can include, but are not limited to, materials represented by the above general formula VI, aromatic dimercaptans, cycloalkyl dimercaptans, heterocyclic dimercaptans, branched dimercaptans, and mixtures thereof.
Non-limiting examples of suitable dimercaptoalkylsulfides for use in the reaction with the reaction product of the asym-dichloroacetone and dimercaptan can include materials represented by the following formula:
wherein X can represent 0, S or Se, n can be an integer from 0 to 10, m can be an integer from 0 to 10, p can be an integer from 1 to 10, q can be an integer from 0 to 3, and with the proviso that (m+n) is an integer from 1 to 20.
Non-limiting examples of suitable dimercaptoalkylsulfides for use in the present invention can include branched dimercaptoalkylsulfides.
The amount of dimercaptan, dimercaptoalkylsulfide, or mixtures thereof suitable for reacting with the reaction product of asym-dichloroacetone and dimercaptan can vary. Typically, dimercaptan, dimercaptoalkylsulfide, or a mixture thereof can be present in the reaction mixture in an amount such that the equivalent ratio of reaction product to dimercaptan, dimercaptoalkylsulfide, or a mixture thereof can be from 1:1.01 to 1:2. Moreover, suitable temperatures for carrying out this reaction can vary within the range of from 0 to 100° C.
The reaction of asym-dichloroacetone with dimercaptan can be carried out in the presence of an acid catalyst. The acid catalyst can be selected from a wide variety known in the art, such as but not limited to Lewis acids and Bronsted acids. Non-limiting examples of suitable acid catalysts can include those described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, 1992, Volume A21, pp. 673 to 674. The acid catalyst is often chosen from boron trifluoride etherate, hydrogen chloride, toluenesulfonic acid, and mixtures thereof. The amount of acid catalyst can vary from 0.01 to 10 percent by weight of the reaction mixture.
The reaction product of asym-dichloroacetone and dimercaptan can alternatively be reacted with dimercaptoalkylsulfide, dimercaptan, or mixtures thereof in the presence of a base. The base can be selected from a wide variety known in the art, such as but not limited to Lewis bases and Bronsted bases. Non-limiting examples of suitable bases can include those described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, 1992, Volume A21, pp. 673 to 674. The base is often sodium hydroxide. The amount of base can vary. Typically, a suitable equivalent ratio of base to reaction product of the first reaction can be from 1:1 to 10:1.
The reaction of asym-dichloroacetone with dimercaptan can be carried out in the presence of a solvent. The solvent can be selected from, but is not limited to, organic solvents. Non-limiting examples of suitable solvents can include, but are not limited to, chloroform, dichloromethane, 1,2-dichloroethane, diethyl ether, benzene, toluene, acetic acid, and mixtures thereof.
In another embodiment, the reaction product of asym-dichloroacetone and dimercaptan can be reacted with dimercaptoalkylsulfide, dimercaptan, or mixtures thereof, with or without the presence of a solvent, wherein the solvent can be selected from but is not limited to organic solvents. Non-limiting examples of suitable organic solvents can include alcohols, such as but not limited to methanol, ethanol and propanol; aromatic hydrocarbon solvents such as but not limited to benzene, toluene, xylene; ketones such as but not limited to methyl ethyl ketone; water; and mixtures thereof.
The reaction of asym-dichloroacetone with dimercaptan can also be carried out in the presence of a dehydrating reagent. The dehydrating reagent can be selected from a wide variety known in the art. Suitable dehydrating reagents for use in this reaction can include but are not limited to magnesium sulfate. The amount of dehydrating reagent can vary widely according to the stoichiometry of the dehydrating reaction.
The polythiols for use in the preparation of the polyurethane material in the first component can be prepared in certain non-limiting embodiments by reacting 2-methyl-2-dichloromethyl-1,3-dithiolane with dimercaptodiethylsulfide to produce dimercapto-1,3-dithiolane derivative of formula III. Alternatively, 2-methyl-2-dichloromethyl-1,3-dithiolane can be reacted with 1,2-ethanedithiol to produce dimercapto-1,3-dithiolane derivative of formula II. 2-methyl-2-dichloromethyl-1,3-dithiane can be reacted with dimercaptodiethylsulfide to produce dimercapto-1,3-dithiane derivative of formula V. Also, 2-methyl-2-dichloromethyl-1,3-dithiane can be reacted with 1,2-ethanedithiol to produce dimercapto-1,3-dithiane derivative of formula IV.
Another non-limiting example of a dithiol suitable for use as the material (ii) can include at least one dithiol oligomer prepared by reacting dichloro derivative with dimercaptoalkylsulfide as follows:
wherein R can represent CH3, CH3CO, C1 to C10 alkyl, cycloalkyl, aryl alkyl, or alkyl-CO; Y can represent C1 to C10 alkyl, cycloalkyl, C6 to C14 aryl, (CH2)p(S)m(CH2)q, (CH2)p(Se)m(CH2)q, (CH2)p(Te)m(CH2)q, wherein m can be an integer from 1 to 5; and p and q can each be an integer from 1 to 10; n can be an integer from 1 to 20; and x can be an integer from 0 to 10.
The reaction of dichloro derivative with dimercaptoalkylsulfide can be carried out in the presence of a base. Suitable bases include any known to those skilled in the art in addition to those disclosed above.
The reaction of dichloro derivative with dimercaptoalkylsulfide may be carried out in the presence of a phase transfer catalyst. Suitable phase transfer catalysts for use in the present invention are known and varied. Non-limiting examples can include, but are not limited to, tetraalkylammonium salts and tetraalkylphosphonium salts. This reaction is often carried out in the presence of tetrabutylphosphonium bromide as phase transfer catalyst. The amount of phase transfer catalyst can vary widely, from 0 to 50 equivalent percent, or from 0 to 10 equivalent percent, or from 0 to 5 equivalent percent, relative to the dimercaptosulfide reactants.
The polythiols may further contain hydroxyl functionality. Non-limiting examples of suitable materials having both hydroxyl and multiple (more than one) thiol groups can include, but are not limited to, glycerin bis(2-mercaptoacetate), glycerin bis(3-mercaptopropionate), 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), pentaerythritol bis(2-mercaptoacetate), pentaerythritol tris(2-mercaptoacetate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol tris(3-mercaptopropionate), and mixtures thereof.
In addition to dithiols disclosed above, particular examples of suitable dithiols can 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), dimercaptodiethylsulfide (DMDS), methyl-substituted dimercaptodiethylsulfide, dimethyl-substituted dimercaptodiethylsulfide, 3,6-dioxa-1,8-octanedithiol, 1,5-dimercapto-3-oxapentane, 2,5-dimercaptomethyl-1,4-dithiane (DMMD), ethylene glycol di(2-mercaptoacetate), ethylene glycol di(3-mercaptopropionate), and mixtures thereof.
Suitable trifunctional or higher-functional polythiols for use in material (ii) can be selected from a wide variety known in the art. Non-limiting examples can include pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), and/or thioglycerol bis(2-mercaptoacetate).
For example, the polythiol can be chosen from materials represented by the following general formula,
wherein R1 and R2 can each be independently chosen from straight or branched chain alkylene, cyclic alkylene, phenylene, and C1-C9 alkyl substituted phenylene. Non-limiting examples of straight or branched chain alkylene can include methylene, ethylene, 1,3-propylene, 1,2-propylene, 1,4-butylene, 1,2-butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, octadecylene, and icosylene. Non-limiting examples of cyclic alkylenes can include cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, and alkyl-substituted derivatives thereof. The divalent linking groups R1 and R2 can be chosen from methylene, ethylene, phenylene, and alkyl-substituted phenylene, such as methyl, ethyl, propyl, isopropyl, and nonyl substituted phenylene.
In particular embodiments, a polythiol may be prepared by reacting together (1) any of the dithiols mentioned above, and (2) a compound having at least two double bonds (for example, a diene) or a compound having a triple bond, such as propargyl alcohol.
The compound (2) having at least two double bonds can be chosen from non-cyclic dienes, including straight chain and/or branched aliphatic non-cyclic dienes, non-aromatic ring-containing dienes, including non-aromatic ring-containing dienes, wherein the double bonds can be contained within the ring or not contained within the ring or any combination thereof, and wherein the non-aromatic ring-containing dienes can contain non-aromatic monocyclic groups or non-aromatic polycyclic groups or combinations thereof; aromatic ring-containing dienes; or heterocyclic ring-containing dienes; or dienes containing any combination of such non-cyclic and/or cyclic groups. The dienes can optionally contain thioether, disulfide, polysulfide, sulfone, ester, thioester, carbonate, thiocarbonate, urethane, or thiourethane linkages, or halogen substituents, or combinations thereof; with the proviso that the dienes contain double bonds capable of undergoing reaction with SH groups of a polythiol, and forming covalent C—S bonds. Often, the compound (2) having at least two double bonds comprises a mixture of dienes that are different from one another.
The compound having at least two double bonds may comprise acyclic non-conjugated dienes, acyclic polyvinyl ethers, allyl-(meth)acrylates vinyl-(meth)acrylates, di(meth)acrylate esters of diols, di(meth)acrylate esters of dithiols, di(meth)acrylate esters of poly(alkyleneglycol) diols, monocyclic non-aromatic dienes, polycyclic non-aromatic dienes, aromatic ring-containing dienes, diallyl esters of aromatic ring dicarboxylic acids, divinyl esters of aromatic ring dicarboxylic acids, and/or mixtures thereof.
Non-limiting examples of acyclic non-conjugated dienes can include those represented by the following general formula:
wherein R can represent C1 to C30 linear or branched divalent saturated alkylene radical, or C2 to C30 divalent organic radical including groups such as but not limited to those containing ether, thioether, ester, thioester, ketone, polysulfide, sulfone and combinations thereof. The acyclic non-conjugated dienes can be selected from 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, and mixtures thereof.
Non-limiting examples of suitable acyclic polyvinyl ethers can include those represented by the following structural formula:
CH2═CH—O—(—R2—O—)m—CH═CH2
wherein R2 can be C2 to C6 n-alkylene, C3 to C6 branched alkylene group, or —[(CH2—)p—O—]q—(—CH2—)r—, m can be a rational number from 0 to 10, often 2, p can be an integer from 2 to 6, q can be an integer from 1 to 5, and r can be an integer from 2 to 10.
Non-limiting examples of suitable polyvinyl ether monomers for use can include divinyl ether monomers, such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, and mixtures thereof.
Di(meth)acrylate esters of linear diols can include ethanediol di(meth)acrylate, 1,3-propanediol dimethacrylate, 1,2-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,2-butanediol di(meth)acrylate, and mixtures thereof.
Di(meth)acrylate esters of dithiols can include, for example, di(meth)acrylate of 1,2-ethanedithiol including oligomers thereof, di(meth)acrylate of dimercaptodiethyl sulfide (i.e., 2,2′-thioethanedithiol di(meth)acrylate) including oligomers thereof, di(meth)acrylate of 3,6-dioxa-1,8-octanedithiol including oligomers thereof, di(meth)acrylate of 2-mercaptoethyl ether including oligomers thereof, di(meth)acrylate of 4,4′-thiodibenzenethiol, and mixtures thereof.
Further non-limiting examples of suitable dienes can include monocyclic aliphatic dienes such as those represented by the following structural formula:
wherein X and Y each independently can represent C1-C10 divalent saturated alkylene radical or C1-C5 divalent saturated alkylene radical, containing at least one element selected from the group of sulfur, oxygen, and silicon in addition to the carbon and hydrogen atoms; and R1 can represent H or C1-C10 alkyl; and
wherein X and R1 can be as defined above and R2 can represent C2-C10 alkenyl. The monocyclic aliphatic dienes can include 1,4-cyclohexadiene, 4-vinyl-1-cyclohexene, dipentene, and terpinene.
Non-limiting examples of polycyclic aliphatic dienes can include 5-vinyl-2-norbornene, 2,5-norbornadiene, dicyclopentadiene, and mixtures thereof.
Non-limiting examples of aromatic ring-containing dienes can include those represented by the following structural formula:
wherein R4 can represent hydrogen or methyl. Aromatic ring-containing dienes can include monomers such as diisopropenyl benzene, divinyl benzene, and mixtures thereof.
Examples of diallyl esters of aromatic ring dicarboxylic acids can include, but are not limited to, those represented by the following structural formula:
wherein m and n each independently can be an integer from 0 to 5. The diallyl esters of aromatic ring dicarboxylic acids can include o-diallyl phthalate, m-diallyl phthalate, p-diallyl phthalate, and mixtures thereof.
Often, the compound (2) having at least two double bonds comprises 5-vinyl-2-norbornene, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, butane diol divinyl ether, vinylcyclohexene, 4-vinyl-1-cyclohexene, dipentene, terpinene, dicyclopentadiene, cyclododecadiene, cyclooctadiene, 2-cyclopentene-1-yl-ether, 2,5-norbornadiene, divinylbenzene including 1,3-divinylbenzene, 1,2-divinylbenzene, and 1,4-divinylbenzene, diisopropenylbenzene including 1,3-diisopropenylbenzene, 1,2-diisopropenylbenzene, and 1,4-diisopropenylbenzene, allyl (meth)acrylate, ethanediol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,2-propanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,2-butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dimercaptodiethylsulfide di(meth)acrylate, 1,2-ethanedithiol di(meth)acrylate, and/or mixtures thereof.
Other non-limiting examples of suitable di(meth)acrylate monomers can include ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 2,3-dimethyl-1,3-propanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, alkoxylated neopentyl glycol di(meth)acrylate, hexylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, thiodiethyleneglycol di(meth)acrylate, trimethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, alkoxylated hexanediol di(meth)acrylate, alkoxylated neopentyl glycol di(meth)acrylate, pentanediol di(meth)acrylate, cyclohexane dimethanol di(meth)acrylate, and ethoxylated bisphenol A di(meth)acrylate.
The polythiols suitable for use in material (ii) in the preparation of the polyurethane material in the first component, when reacted with a polyisocyanate (i), can produce a polymerizate having a Martens hardness of at least 20 N/mm2, or often at least 50, or more often between 70 and 200. Such polymerizates are typically not elastomeric; i.e., they are not substantially reversibly deformable (e.g., stretchable) due to their rigidity and do not typically exhibit properties characteristic of rubber and other elastomeric polymers.
The active hydrogen component also can further comprise at least one amino alcohol, i.e., a compound containing both amine and hydroxyl functional groups. The amino alcohol has the structure H2N-L-OH, wherein L is a linear or branched alkyl, aryl, aralkyl, or alkaryl chain which may contain hetero atoms. In particular embodiments, the amino alcohol has the structure H2N—CH2-L′-CH2—OH, wherein L′ is a linear or branched alkyl, aryl, aralkyl, or alkaryl chain which may contain hetero atoms. Such materials more often have the structure:
wherein R is H or a C1 to C4 alkyl group, and n is an integer from 1 to 10.
As noted above, the amino alcohol is often aliphatic. Aliphatic materials lend better flexibility to the final product, providing better impact resistance. Optical products prepared according to the method of the present invention, with aliphatic materials, also demonstrate better light stability and less yellowing compared to those prepared with aromatic materials. Aromatic starting materials, such as aromatic amines, are also known to have relatively short shelf lives and are subject to oxidation and yellowing.
It is somewhat counterintuitive to use aliphatic materials because aliphatic polyamines react too quickly with isocyanates to control the formation of a polyurea, resulting in very short gel times. However, the use of an aliphatic compound containing both amine and hydroxyl functional groups as in the present invention slows the reaction with the isocyanate compared to a reaction of an aliphatic polyamine with an isocyanate. At the same time, the use of an aliphatic compound containing both amine and hydroxyl functional groups provides for desirable physical properties in the final product, such as thermal stability and hardness, allowing for post-production lens processing. It is believed that this is due to the urea linkages present in the polymerizate. Urea linkages also render the final product non-elastomeric.
The compound containing both amine and hydroxyl functional groups typically has a number average molecular weight of 60 to 450. Materials having higher molecular weights may contribute to opaqueness. Often, the material containing both amine and hydroxyl functional groups comprises ethanolamine, diethanolamine, amino-2-propanol, 2-amino-1-methyl-1-propanol, 2-amino-1-butanol, and/or 2-(2-aminoethoxy)ethanol (diethyleneglycol amine, or DGA). Typically, the material containing both amine and hydroxyl functional groups is present in the active hydrogen component (b) in an amount of 5 to 70 percent by weight, often 10 to 70 percent by weight, more often 15 to 50 percent by weight, based on the total weight of resin solids in component (b). Typically, the material containing both amine and hydroxyl functional groups is present in the reaction mixture in an amount of 5 to 25 percent by weight, based on the total weight of resin solids in the reaction mixture.
Additionally, in certain embodiments of the present invention, the reaction mixture is essentially free of polyamines. In particular, the active hydrogen component is often essentially free of 2,4-diamino-3,5-diethyl-toluene, 2,6-diamino-3,5-diethyl-toluene, and mixtures thereof (collectively “diethyltoluenediamine” or “DETDA”).
As previously mentioned, the organic polymerizable composition of the present invention optionally comprises urethanation catalyst. Non-limiting examples of suitable catalysts can be chosen from the group of Lewis bases, Lewis acids, and insertion catalysts as described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, 1992, Volume A21, pp. 673 to 674. The catalyst can be a stannous salt of an organic acid, such as but not limited to stannous octoate, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin mercaptide, dibutyl tin dimaleate, dimethyl tin diacetate, dibutyltin dichloride, and mixtures thereof. The catalyst can alternately be zinc octoate, bismuth, or ferric acetylacetonate.
Further non-limiting examples of suitable catalysts can include tin compounds such as dibutyl tin oxide, phosphines, tertiary ammonium salts, and tertiary amines, such as but not limited to triethylamine, triisopropylamine, dimethyl cyclohexylamine, 1,4-diazabicyclo[2.2.2]octane, N, N-dimethylbenzylam ine, and mixtures thereof. Such suitable tertiary amines are disclosed in U.S. Pat. No. 5,693,738 at column 10, lines 6-38, the disclosure of which is incorporated herein by reference.
When employed, the catalyst level can vary and can be dependent upon a variety of factors, such as the type and amounts of the reactive compounds used, as well as reaction conditions, speed of reaction, and degree of reaction desired. Typically, an organotin catalyst is present in component (b) in an amount less than 300 ppm, often less than 250 ppm, and a tertiary amine catalyst is present in an amount less than 1000 ppm, usually less than 800 ppm, often about 720 ppm, based on the total weight of (b).
It should further be mentioned that other commonly used solvents and/or additives can be included in the compositions of the present invention, if desired. Suitable solvents may include any organic solvents known to those skilled in the art, provided they are not reactive with isocyanate functional groups. Examples of solvents are ketones, furans, aromatic solvents, and chlorinated solvents. Suitable solvents can include but are not limited to acetone, amyl propionate, anisole, benzene, butyl acetate, cyclohexane, dialkyl ethers of ethylene glycol, e.g., diethylene glycol dimethyl ether and their derivatives (sold as CELLOSOLVE® industrial solvents), diethylene glycol dibenzoate, dimethyl sulfoxide, dimethyl formamide, dimethoxybenzene, ethyl acetate, methyl cyclohexanone, cyclopentanone, methyl ethyl ketone, methyl isobutyl ketone, methyl propionate, propylene carbonate, tetrahydrofuran, toluene, xylene, 2-methoxyethyl ether, 3-propylene glycol methyl ether, methylene chloride, and mixtures thereof. Suitable additives can include but are not limited to light stabilizers, heat stabilizers, antioxidants, ultraviolet light absorbers, static (non-photochromic) dyes, pigments, and flexibilizing additives.
As mentioned previously, any of the above-described organic polymerizable compositions of the present invention are particularly useful in the production of molded polymeric articles, for example, windshields, sunglasses, fashion lenses, non-prescription and prescription lenses, sport masks, face shields, and goggles.
Any of the aforementioned organic polymerizable compositions of the present invention may be introduced into a mold of any desired shape at a temperature and for a time to form a polymerizate, such as a thermoset polymerizate. The reaction mixture can undergo an exothermic reaction and, after mixing, it is introduced, usually by injection, into a mold and, in the case of lenses, a glass mold. The temperature of the reaction mixture as it is introduced into the mold can be up to 130° C., often up to 120° C. The reaction mixture is held in the mold at a temperature and for a time sufficient to essentially cure the reaction mixture and form a molded optical article. The mold may have any shape desired for the final product. It is typically a lens mold; often a mold for an ophthalmic lens. The molded article may then be released from the mold. Alternatively, the reaction mixture, which can be optionally degassed, can be introduced, usually by injection, into a mold and the mold can be heated (i.e., using a thermal cure cycle) using a variety of conventional techniques known in the art. The thermal cure cycle can vary depending on the reactivity and molar ratio of the reactants, and the presence of catalyst(s). The thermal cure cycle can include heating the mixture from room temperature to a temperature of 200° C. over a period of from 0.5 hours to 120 hours; or from 80 to 150° C. for a period of from 5 hours to 72 hours.
Various embodiments disclosed herein will now be illustrated in the following non-limiting examples.
Throughout the course of this set of experiments, the following two experimental formulations, as summarized in Table 1 below, were used during casting trials.
1a cycloaliphatic diisocyanate available from Covestro AG.
Several comparative examples were made, which used alternative salts (in this case, chloride salts in place of the fluoride salts). In each example and comparative example, the first three components for Formulation A were combined in an Erlenmeyer flask according to the weight ratio designated in Table 1. They were then mixed using a magnetic stir plate and magnetic stir bar to achieve a homogeneous liquid at 25° C. To this mixture were added the fluoride or chloride salt, and ZELEC® UN (a mold release agent available from Stepan Company) as indicated in Table 3. The combined mixture was degassed at room temperature under vacuum for 4 hours.
To cast the composition, components mixed above and DESMODUR® W were mixed together under vacuum and heated until reaching a homogeneous appearance. The resulting mixture then was charged into the cavity of a mold comprised of two pieces of plate glass with dimensions 15 cm×15 cm×0.3 cm defined by a gasket there around. The contents of the glass mold then were cured in an oven using the following temperature scheme: 1) start at 70° C., and gradually heat to 130° C. over a period of 1 hour; 2) hold the temperature at 130° C. for 16 hours; 3) gradually decrease the temperature to 60° C. over a period of 1 hour. After being cured under the aforementioned curing conditions, the samples were removed from the oven, and cooled. Then demolding was attempted as described below.
The gasket material was first removed from the edge of the molded article and the glass/polymer interface was scored with a putty knife to induce separation. A wedge also was used in some instances to separate the glass sheets from the cast polymer. Demoldability of the polymer was evaluated on a scale of 1 to 3 as shown in Table 2 below.
A summary of the comparison experiments can be found in Table 3 below.
As shown in Table 3, polymer release in the demolding process is facilitated by the use of fluoride anion as the active IMR.
To investigate the effect of other commercially available internal mold release agents (“IMRs”), ammonium fluoride was the only fluoride salt used in Part III. Part III used Formulation B in place of Formulation A. Thus, the first four components of Formulation B were combined according to the weight ratio designated in Table 1 above. These components were mixed similarly as those of Formulation A in Part II, with the exception that cyclohexanedimethanol was melted at around 60-65° C. prior to use. The casting and demolding processes of Formulation B, ammonium fluoride, and co-IMRs (as indicated in Table 4) were carried out using similar procedures as outlined in Part II above. The following Table 4 summarizes the comparison of polymer demoldability using different IMRs.
1an internal mold release agent available from Axel Plastics Research Laboratories, Inc.
2an internal mold release agent available from Axel Plastics Research Laboratories, Inc.
3an internal mold release agent available from Axel Plastics Research Laboratories, Inc.
As shown in Table 4, ammonium fluoride alone without the inclusion of an IMR was sufficient to release the polymer from the glass molds. The addition of some IMRs further improved polymer demoldability, allowing for lower fluoride content.
In addition to ammonium fluoride in Part III, a variety of fluoride sources were investigated in Part IV. Similar to Part II, Formulation A and ZELEC® UN (1 part by weight as co-IMR) were used in all cases with and without additional fluoride sources. The mixing, casting, and demolding processes of Formulation A and ZELEC® UN with and without fluoride salts follow similar procedures as in Part II. Table 5 shows the comparison among different fluoride sources, as well as the lowest levels of fluoride salt at which complete demoldability was achieved.
As shown in Table 5, the comparison between Comparative Example 12 and Examples 13 to 18 indicates that the addition of fluoride to the polymer formulation greatly increased the demoldability of the final polymer.
Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.
This application is a continuation of U.S. patent application Ser. No. 15/210,269, filed Jul. 14, 2016, which claims the benefit of priority from U.S. Provisional Application No. 62/193,797, filed Jul. 17, 2015, both of which are incorporated herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62193797 | Jul 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15210269 | Jul 2016 | US |
| Child | 16228965 | US |
