Quaternary Nitrogen Compound for Use as a Latent Catalyst in Curable Compositions

Abstract

The present application relates to a quaternary nitrogen compound comprising a nitrogen heterocycle wherein: at least one polymeric substituent is bound to a ring atom of said heterocycle; and, an aromatic photoremovable group (PRG) is directly bound to a quaternary nitrogen ring atom of said heterocycle, the release of said aromatic photoremovable group under UV irradiation yielding a tertiary amine. The application further relates to the use of said quaternary nitrogen compound as a latent catalyst in a curable composition, the curing of which may be catalyzed or co-catalyzed by tertiary amines.

Claims

1. A quaternary nitrogen compound comprising a nitrogen heterocycle wherein: at least one polymeric substituent is bound to a ring atom of said heterocycle; and, an aromatic photoremovable group (PRG) is directly bound to a quaternary nitrogen ring atom of said heterocycle, the release of said aromatic photoremovable group under UV irradiation yielding a tertiary amine.

2. The compound according to claim 1 comprising a stoichiometric amount of a counter ion of anionic charge selected from halides and non-coordinating anions comprising an element selected from boron, phosphorous or silicon.

3. The compound according to claim 1 comprising an unsaturated monocyclic or bicyclic nitrogen heterocycle having at least two ring nitrogen atoms.

4. The compound according to claim 1, wherein said aromatic photoremovable group (PRG) is represented by the formula:
CR.sup.1R.sup.2Ar wherein: R.sup.1 and R.sup.2 are independently of one another hydrogen or C1-C6 alkyl; Ar represents an aryl group having from 6 to 18 ring carbon atoms, which aryl group may be unsubstituted or may be substituted by one of more C1-C6 alkyl group, C2-C4 alkenyl group, CN, OR.sup.3, SR.sup.3, CH.sub.2OR.sup.3, C(O)R.sup.3, C(O)OR.sup.3 or halogen; and, where present, each R.sup.3 is independently selected from the group consisting of hydrogen, C1-C6-alkyl and phenyl.

5. The compound according to claim 4, wherein: at least one of R.sup.1 and R.sup.2 is hydrogen; and Ar represents an aryl group having from 6 to 18 ring carbon atoms, which aryl group may be unsubstituted or may be substituted by one or more C1-C6 alkyl group, C2-C4 alkenyl group, C(O)R.sup.3 or halogen.

6. The compound according to claim 1, wherein said compound is denoted by the general formula:
Y-(L--PRG).sub.r wherein: Y is an r-valent polymeric radical selected from the group consisting of polyolefins, polyethers, polyesters, polycarbonates, vinyl polymers and copolymers thereof; L is a covalent bond or an organic linking group; represents a nitrogen heterocycle having a quaternary nitrogen ring atom with which is associated a charge balancing anion; PRG is said aromatic photoremovable group bound to a quaternary nitrogen ring atom of said heterocycle; and, r is an integer of at least 1, an integer of from 1 to 5.

7. The compound according to claim 6 wherein the group --PRG is represented by either: ##STR00008## wherein: n is 1, 2 or 3; R.sup.4 is hydrogen, C1-C6 alkyl, phenyl or a polymeric substituent which is represented by the general formula -LY in which L is a covalent bond or an organic linking group and Y is a polymeric radical selected from the group consisting of polyolefins, polyethers, polyesters, polycarbonates, vinyl polymers and copolymers thereof; and, X.sup.m is a counter ion of anionic charge m selected from halides and non-coordinating anions comprising an element selected from boron, phosphorous or silicon.

8. The compound according to claim 6, wherein said r-valent polymeric radical Y is a polyether selected from group consisting of polyalkylene oxides and copolymers thereof.

9. The compound according to claim 6, wherein said r-valent polymeric radical Y is either a linear homopolymer of ethylene oxide or propylene oxide or a linear copolymer of ethylene oxide and propylene oxide or a linear copolymer of ethylene oxide, propylene oxide and butylene oxide.

10. The compound according to claim 6, wherein said r-valent polymeric radical Y has a weight average molecular weight of from 100 to 100,000.

11. A latent catalyst in a curable composition comprising the compound defined in claim 1.

12. The latent catalyst defined in claim 11 wherein irradiation with ultraviolet light having: a wavelength of from 150 to 600 nm, from 200 to 450 nm; and/or an energy of from 5 to 500 mJ/cm.sup.2, from 50 to 400 mJ/cm.sup.2 catalyzes cure of the curable composition.

13. A polyurethane coating, adhesive or sealant composition comprising: a) a polyisocyanate; b) a polyol; and, c) a latent catalyst comprising at least one compound as defined in claim 1.

14. The composition according to claim 13 comprising said latent catalyst in an amount of from 0.01 to 10 wt. %, based on the total weight of the composition.

15. A curable epoxy-resin composition comprising: a) an epoxy resin; b) a latent catalyst comprising at least one compound as defined in claim 1; and optionally c) a curative for said epoxy resin.

16. The composition according to claim 15 comprising said latent catalyst in an amount of from 0.01 to 5 wt. %, based on the total weight of the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0058] The invention will now be described with reference to a number of more detailed embodiments.

[0059] At its broadest, the present invention defines a quaternary nitrogen compound which may find utility as a latent catalyst which is activatable under ultraviolet irradiation. More particularly, the quaternary nitrogen compound comprises a nitrogen heterocycle wherein an aromatic photoremovable group (PRG) is directly bound to a quaternary nitrogen ring atom of said heterocycle, the release of said aromatic photoremovable group under UV irradiation yielding a tertiary amine. To at least one ring atom of the nitrogen heterocyclic compound is bound a polymeric substituent, which polymeric substituent(s) should be characterized by a molecular weight of from 100 to 100,000 and more by a molecular weight of from 400 to 7500 g/mol.

[0060] The quaternary nitrogen compound typically comprises an unsaturated monocyclic or bicyclic nitrogen heterocycle having at least two ring nitrogen atoms. Monocyclic nitrogen heterocycles will be characterized by comprising from 3 to 9 non-hydrogen atoms or more from 5 to 9 non-hydrogen atoms: said 5 to 9 membered monocyclic rings should further be characterized by having 2 or 3 nitrogen heteroatoms therein. Bicyclic nitrogen heterocycles will have two fused rings and be characterized by containing in toto from 7 to 12 non-hydrogen atoms and from 2 to 4 nitrogen heteroatoms. at least one and more both of the fused rings will contain 5 or 6 non-hydrogen atoms. Nitrogen atoms may be disposed at the ring junctions of the bicyclic nitrogen heterocycles.

[0061] Within the quaternary nitrogen compound, the positively charged nitrogen atom is that nitrogen atom to which the aromatic photoremovable group is bound. The compound is electrically neutral on account of containing a stoichiometric amount of a counter ion of anionic charge and, that counter ion is selected from halides and non-coordinating anions comprising an element selected from boron, phosphorous or silicon. In selecting counter anions of this type, the quaternary nitrogen compound can be characterized as being metal-free.

[0062] In an important aspect of the present invention, the aromatic photoremovable group (PRG) is directly bonded to a quaternary nitrogen ring atom of the heterocycle and is represented by the formula:

CR.sup.1R.sup.2Ar (PRG)

wherein: R.sup.1 and R.sup.2 are independently of one another hydrogen or C1-C6 alkyl;

[0063] Ar represents an aryl group having from 6 to 18 ring carbon atoms, which aryl group may be unsubstituted or may be substituted by one of more C1-C6 alkyl group, C2-C4 alkenyl group, CN, OR.sup.3, SR.sup.3, CH.sub.2OR.sup.3, C(O)R.sup.3, C(O)OR.sup.3 or halogen; and,

[0064] where present, each R.sup.3 is independently selected from the group consisting of hydrogen, C1-C6-alkyl and phenyl.

[0065] As regards the aforementioned general formula (PRG), it is preferred that:

[0066] At least one of R.sup.1 and R.sup.2 is hydrogen; and

[0067] Ar represents an aryl group having from 6 to 18 ring carbon atoms, which aryl group may be unsubstituted or may be substituted by one of more C1-C6 alkyl group, C2-C4 alkenyl group, C(O)R.sup.3 or halogen.

[0068] As noted above, in a number of important embodiments, the quaternary ammonium compound may be denoted by the general formula:

Y-(L--PRG).sub.r

wherein: Y is an r-valent polymeric radical selected from the group consisting of polyolefins, polyethers, polyesters, polycarbonates, vinyl polymers and copolymers thereof; [0069] L is a covalent bond or an organic linking group; [0070] represents a nitrogen heterocycle having a quaternary nitrogen ring atom with which is associated a charge balancing anion; [0071] PRG is an aromatic photoremovable group bound to a quaternary nitrogen ring atom of said heterocycle; and, [0072] r is an integer of at least 1, an integer of from 1 to 5.
The integer r may be, for instance, from 1 to 4 or from 1 to 3.

[0073] As the r-valent polymeric radical (Y), suitable polyolefins include, but are not limited to, homopolymers or copolymers of ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 5-methyl-1-hexane and mixtures thereof. Preferred polyolefins include polyethylene, polypropylene, polybutylene and copolymers of ethylene and propylene.

[0074] Suitable polyesters include, but are not limited to, polyethylene terephthalate and polybutylene terephthalate. Suitable polycarbonates include, but are not limited to, those prepared by the reaction of diols, such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, or thiodiglycol, with phosgene or diaryl carbonates, such as diphenyl carbonate. Exemplary polycarbonates, including polyestercarbonates, are disclosed in: German Auslegeschriften 1,694,080, 1,915,908, and 2,221,751; German Offenlegungsschrift 2,605,024; U.S. Pat. Nos. 4,334,053; 6,566,428; and, Canadian Patent No. 1,173,998.

[0075] Suitable vinyl polymers include, but are not limited, to homo- and copolymers of: vinyl halides, such as vinyl chloride, vinyl fluoride and vinylidene fluoride; vinyl ethers, such as methyl vinyl ether and isobutyl vinyl ether; vinyl esters of the formula CH.sub.2CHOCOR, where R is C.sub.1-C.sub.18 alkyl; chloroprene; isoprene; styrene and derivatives thereof, particularly alkyl-substituted styrene; monoesters and diesters of fumaric, itaconic and maleic acids; C.sub.1-C.sub.18 alkyl esters of acrylic acid; C.sub.1-C.sub.18 alkyl esters of methacrylic acid; hydroxy functional acrylates and methacrylates, such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate; acrylamides; methacrylamides; non-alkyl-substituted acrylamides, such as diacetone acrylamide; and, acyclic N-vinyl amides such as N-vinyl acetamide and N-methyl-N-vinyl acetamide.

[0076] It is envisaged that copolymers of vinyl monomers with olefins may find utility in the present invention and mention may thus be made of copolymers of: ethylene vinylacetate; ethylene butylacrylate; and, ethylene methylacrylate.

[0077] In an important embodiment, the r-valent polymeric radical (Y) is a polyether selected from group consisting of polyalkylene oxides and copolymers thereof. Exemplary but non-limiting polyalkylene oxides include linear homopolymers of ethylene oxide or propylene oxide and linear copolymers of ethylene oxide, propylene oxide and, optionally, butylene oxide.

[0078] In certain exemplary embodiments wherein the quaternary nitrogen compound the quaternary ammonium compound may be denoted by the aforementioned general formula Y-(L--PRG).sub.r, the group --PRO may more particularly be represented by either:

##STR00001##

wherein: PRG is as defined above; [0079] n is 1, 2 or 3; [0080] R.sup.4 is hydrogen, C1-C6 alkyl, phenyl or a polymeric substituent which is represented by the general formula -LY in which L is a covalent bond or an organic linking group and Y is a polymeric radical selected from the group consisting of polyolefins, polyethers, polyesters, polycarbonates, vinyl polymers and copolymers thereof; and, [0081] X.sup.m is a counter ion of anionic charge m selected from halides and non-coordinating anions comprising an element selected from boron, phosphorous or silicon.

[0082] The polymeric radical (Y.) may be the same as or different from the polyvalent radical (Y).

[0083] Said non-coordinating anions consist, typically, of a compound of said elements (B, P or Si) having a formal valence m with more than m radicals which independently may be: a hydride radical; a bridged or unbridged dialkylamido radical; an alkoxide and aryloxide radical; a hydrocarbyl or substituted hydrocarbyl radical; or, a halocarbyl or substituted halocarbyl radical. The charge of the anion equals the number of radicals minus the formal valence (m) of the (metalloid) element. The disclosure of U.S. Pat. No. 5,198,401 may be instructive on suitable non-coordinating anions of the elements B, P and Si.

[0084] For illustration, suitable boron-containing anions include: tetra(phenyl)borate; tetra(p-tolyl)borate; tetra(o-tolyl)borate; tetra(pentafluorphenyl)borate; tetra(o,p-dimethylphenyl)borate; tetra(m,m-dimethylphenyl)borate; and, tetra(p-trifluoromethylphenyl)borate.

Synthesis of the Latent Catalysts

[0085] Without intention to limit the present invention, the quaternary nitrogen compounds are derivable from a multi-stage synthesis, of which Examples are provided herein under. A suitable synthetic method may be described as comprising the following stages: [0086] i) forming an adduct (A) of a homo- or copolymer (Y) with an appropriate, defined nitrogen heterocyclic compound; [0087] ii) reacting said adduct (A) with a halide-functional aralkylating agent to bind the aromatic photoremovable group (PRG) thereto; and, [0088] iii) where applicable, swapping any halide anion present in the product of stage ii) with a non-coordinating anion (X).

Stage i)

[0089] The first stage defined above will typically be constituted by the nucleophilic addition of a nucleophile to an electrophile. To effect this addition where the starting heterocyclic compound or the (co)polymer (Y) do not possess appropriate functional groups, one or both of these compounds may be functionalized with a group (L.sup.a), the residue of which group will become incorporated in the adduct as linking group L.

[0090] Generally the adducts are prepared via either a nucleophilic substitution (S.sub.N2) using an electrophile containing polymer or the Michael addition reaction of a molar excess of a functionalized polymer (Y-L.sup.a) with the nitrogen heterocyclic compound, typically in the presence of a chlorinated hydrocarbon solvent and/or an aromatic solvent, such a toluene. Exemplary chlorinated hydrocarbon solvents include methylene chloride, ethylene dichloride, 1,1,1-trichloroethane and chloroform.

[0091] Depending on the functional groups present in the reacting monomers and also on inherent steric effects, it is possible for pendant electrophilic groups (L.sup.a), and in particular (meth)acrylate groups, to be incorporated into polymers (Y) through copolymerization with ethylenically unsaturated monomers: suitable co-polymerization methods include ionic polymerization, conventional radical polymerization, polycondensation and controlled radical polymerization (CRP). Alternately, the pendant electrophilic groups can be incorporated into the (co)polymer (Y) by making the polymer and then post-functionalizing it via subsequent reaction(s).

[0092] It is considered that polymerization processes and post-functionalization may be carried in facile manner by the skilled artisan. The following disclosures are also considered instructive in this regard: H. Mark, et al., Ed., Encyclopedia of Polymer Science and Engineering, 2nd Ed., Vol. 12, John Wiley & Sons, New York, 1988; H. Mark et al., Ed., Encyclopedia of Polymer Science and Engineering, 2nd Ed., Supplement Volume, John Wiley & Sons, New York, 1989.

[0093] For illustration, and without intention to limit the present invention, the reactant polymer of a Michael addition (Stage i)) may have the formula:

##STR00002##

wherein: R is hydrogen or methyl; [0094] n is 2; and, [0095] Y is the homopolymer or copolymer described above, with the caveat that said (co)polymer Y should not interfere with the Michael addition.
In this illustrative embodiment, it preferred that Y is selected from group consisting of polyalkylene oxides and copolymers thereof.

[0096] A base may optionally be used to catalyze the Michael addition reaction. Further, the Michael addition reaction can occur at room temperature but the rate of reaction can be increased at elevated temperatures, for example up to 100 C. The synthesis method is not so limited, however, and the reaction can be conducted at temperatures outside of these ranges. The reaction times can inevitably vary but a time frame of from 1 hour to 1 week may be considered typical: if necessary, the progress of the addition reaction can be followed by inter alia chromatography.

[0097] The crude product obtained from the addition reaction is desirably worked up prior to being employed in the further synthesis stages. As methods of separation and isolation of the Adduct (A) mention may be made of extraction, evaporation, re-precipitation, distillation and chromatography.

Stage ii)

[0098] This stage of the illustrative synthesis method comprises the reaction of the Adduct (A) with a halide-containing aralkylating agent, which agent thereby binds the photoremovable group (PRG) to a nitrogen atom disposed in the heterocylic ring.

[0099] Substituted or unsubstituted chloroalkyl compounds and especially chloromethyl compounds of aromatic or partially hydrogenated aromatic compounds are particularly suitable as aralkylating agents in the present invention. As is known in the art, such chloromethyl derivatives of aromatic and partially hydrogenated aromatic hydrocarbons can be prepared by the introduction, under heating to 60-70 C., of hydrogen chloride gas into a mixture of the hydrocarbon, concentrated formaldehyde, concentrated aqueous hydrochloric acid and, optionally, zinc chloride. Exemplary chloromethyl derivatives include, but are not limited to: chloromethyl toluene; chloromethyl xylene; chloromethyl cumene; 2-chloromethyl cymene; 1-chloromethyl naphthalene; chloromethylcyclohexyl-benzene, obtainable, for example, by treatment of the addition product of benzene and cyclohexene with formaldehyde, aqueous hydrochloric acid and hydrogen chloride gas at 60-70 C.; chloromethyl anthracene; chloromethyloctahydroanthracene; and, chloromethyloctahydrophenanthrene.

[0100] Further known aralkylating agents useful in the present invention include: alkylbenzyl halides, such as octylbenzyl chloride; and, halogen ketones, such as chloroacetophenone and bromoacetophenone.

[0101] The reaction of the amines with the aralkylating agents is generally performed in the presence of an aprotic solvent and, optionally, acid-binding agents, such as sodium carbonate or calcium carbonate. The aprotic solvent should be stable to the action of the aralkylating agent and any such bases present and suitable solvents which may be mentioned in this regard include: simple linear ethers, such as diethyl ether and methyl-t-butyl ether; cyclic ethers, such as tetrahydrofuran and 1,4-dioxane; glyme ethers; amides, such as dimethylformamide; and, mixtures thereof.

[0102] Good results have been obtained where this aralkylation stage is performed under anhydrous conditions. If desired, exposure to atmospheric moisture may be avoided by providing the reaction vessel with an inert, dry gaseous blanket. Whilst dry nitrogen, helium and argon may be used as blanket gases, precaution should be used when common nitrogen gases are used as a blanket, because such nitrogen may not be dry enough on account of its susceptibility to moisture entrainment; the nitrogen may require an additional drying step before use herein.

[0103] The aralkylation reaction is normally performed at a temperature of from 20 to 100 C. The progress of the reaction can be monitored by inter alia chromatography: whilst the reactivity of the aralkylating agent is determinative of the duration of the reaction, a duration of from 2 to 48 hours will be standard.

[0104] After completion of the reaction, the crude reaction product may itself be used in the next, optional stage of the synthesis. However, the working up of the product is not precluded and an illustrative procedure would entail the evaporation of the solvent from the reaction mixture under sub-atmospheric pressure and the iterative (re-) precipitation of the product in a suitable solvent, such as diethyl ether. The product may, if desired, be further purified using methods known in the art such as extraction, evaporation, distillation and chromatography.

Stage iii)

[0105] In the final synthesis stage, the halide counterion present after the aralkylation stage may be swapped with the aforementioned non-coordinating anions (hereinafter X).

[0106] The crude or separated and purified aralkylation product of stage ii) is contacted with a polar solvent. Such a solvent comprises at least one compound selected from: alcohols, such as methanol or methoxyethanol; amide solvents, such as N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF) and N-methylpyrrolidone (NMP); dimethylsulfoxide (DMSO); halocarbons, such as dichloromethane (DCM) and chloroform; esters, such as ethyl acetate (AcOEt) and isopropyl acetate (AcOiPr); ethers, such as diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran (THF) and MTBE; pyridine; and, acetonitrile. Good results have been obtained where the solvent is selected from: methanol; methoxyethanol; N,N-dimethylacetamide (DMA); N-methylpyrrolidone (NMP); N,N-dimethylformamide (DMF); and, mixtures thereof.

[0107] The solution thus obtained is mixed with a salt (CatX), wherein Cat denotes a cation selected from the group consisting of: protons (H.sup.+); alkali earth metal cations; and, alkaline earth metal cations. Cat is an alkali metal cation and more particularly Na.sup.+ or K.sup.+.

[0108] In this synthesis stage, at least 1 mole, for example from 1 to 5 moles, of the salt (CatX) ought to be used per mole of the aralkylation product. It will be evident to the skilled partisan that smaller amounts of the salt (CatX) may be used but this may lead to only partial reaction of the aralkylation product. In any event, the desired amount of salt (CatX) may be introduced in solution, whereby the salt is dissolved in the minimum amount of the solvent employed for the aralkylation product.

[0109] The solution obtained after adding the salt (CatX) is stirred until the reaction is complete, either at room temperature or at a slightly elevated temperature up to and including 80 C. The progress of the reaction can be monitored by chromatography, for example, but it is noted that a reaction duration of from 1 to 24 hours will be standard.

[0110] The crude product obtained may then be worked up, for which an illustrative procedure would entail the evaporation of the solvent from the reaction mixture under sub-atmospheric pressure, the dissolution of the obtained mixture in a suitable solvent, such as tetrahydrofuran, followed by filtration of the obtained solution to remove the halide salts; the filtrate may then be collected and the solvent evaporated there-from under reduced pressure. The so-obtained product may, if desired, be further purified using methods known in the art such as extraction, evaporation, re-crystallization, distillation and chromatography.

Methods and Applications

[0111] An important aspect of the present invention is the provision of a latent catalyst comprising at least one quaternary nitrogen compound as defined above. Such latent catalysts may find utility in any polymerization process, curable system or reactive system which may be catalyzed or co-catalyzed by tertiary amines. Without intention to limit the present invention, mention may be made of: curable systems containing an epoxy resin; curable systems comprising an isocyanate and an active hydrogen compound, such as an alcohol, a polyol, a thiol or a primary or secondary amine; the polymerization of ethylenically unsaturated monomers as described in U.S. Pat. No. 2,559,855 (Coover et al.); the Bayliss-Hillman coupling reaction; and, aldol condensation reactions.

[0112] In a particular embodiment, the present invention defines a polyurethane coating, adhesive or sealant composition comprising: a) a polyisocyanate; b) a polyol; and, c) a latent catalyst comprising at least one quaternary nitrogen compound as described herein before. As will be recognized by the skilled artisan, the polyisocyanate and the polyol should be present in such compositions in a pre-determined amount, selected to achieve the desired molar ratio of isocyanate (NCO) groups to hydroxyl groups (OH): that NCO:OH molar ratio should typically be in the range from 0.8:1 to 2.5:1, from 1.3:1 to 1.8:1. The latent catalyst is desirably used in an amount of from 0.01 to 10 wt. %, and from 0.01 to 5 wt. %, based on the total weight of the composition.

[0113] Such a polyurethane composition will desirably be a two component (2K) composition: the latent catalyst of the present invention may be disposed in one or both of the polyisocyanate (1.sup.st) and polyol (2.sup.nd) components. However, in a 2K composition, it is preferred that said latent catalyst be disposed exclusively in the polyol component (2.sup.nd) of the composition.

[0114] In another interesting embodiment, the present invention defines a curable epoxy-resin composition for use as a coating, adhesive or sealant composition or as a matrix for composite materials, said epoxy resin composition comprising: a) an epoxy resin; b) a latent catalyst comprising at least one quaternary nitrogen compound as described herein before; and, optionally, c) a curative for said epoxy resin. The latent catalyst is desirably used in an amount of from 0.01 to 10 wt. %, and from 0.01 to 5 wt. %, based on the total weight of the epoxy resin composition.

[0115] In certain embodiments, the epoxy resin compositions will comprise the epoxy resin and a curative in pre-determined amount; generally, the curative may be present in the composition in stoichiometric amounts 50% relative to the epoxy resin component, with 80-100% of stoichiometry being preferred. For instance, where a curative contains active hydrogen atoms, the equivalence ratio of active hydrogen atoms relative to the epoxy groups in the resin should be in the range from 1:0.5 to 1:1.5 and more in the range from 1:0.8 to 1:1.2.

[0116] Whilst one component epoxy resin compositions of this type are not precluded, the compositions are desirably two-component compositions, with the first component containing the epoxy resin and the second component containing the curative and the latent catalyst.

[0117] There is no particular intention to limit the suitable curatives but specific mention may be made of: aliphatic polyamines, such as chain aliphatic polyamines, alicyclic polyamines and aliphatic aromatic polyamines; aromatic polyamines, such as metaphenylene diamine (MPDA), diaminodiphenyl methane (DDM) and diaminodiphenyl sulfone (DDS); amido amines; phenolics; thiols; and, polycarboxylic acids and anhydrides. And the disclosure of Lee et al. Handbook of Epoxy Resins, McGraw-Hill, pages 36-140, New York (1967) may be instructive in this regard.

[0118] As is standard in the art, curable compositions and, in particular, the above defined polyurethane and epoxy resin compositions may comprise additives and adjunct ingredients, provided these do not detrimentally affect the desired properties of the composition. Suitable additives and adjunct ingredients include: co-catalysts; antioxidants; UV absorbers/light stabilizers; metal deactivators; antistatic agents; reinforcers; fillers; antifogging agents; propellants; biocides; plasticizers; lubricants; emulsifiers; dyes; pigments; rheological agents; impact modifiers; adhesion regulators; optical brighteners; flame retardants; anti-drip agents; nucleating agents; wetting agents; thickeners; protective colloids; defoamers; tackifiers; solvents; reactive diluents; and, mixtures thereof. The selection of suitable conventional additives for the compositions of the invention depends on the specific intended use thereof and can be determined in the individual case by the skilled artisan.

[0119] Where employed, light stabilizers/UV absorbers, antioxidants and metal deactivators should have a high migration stability and temperature resistance. They may suitable be selected, for example, from the groups a) to t) listed herein below, of which the compounds of groups a) to g) and i) represent light stabilizers/UV absorbers and compounds j) to t) act as stabilizers: a) 4,4-diarylbutadienes; b) cinnamic acid esters; c) benzotriazoles; d) hydroxybenzophenones; e) diphenyl cyanoacrylates; f) oxamides; g) 2-phenyl-1,3,5-triazines; h) antioxidants; i) nickel compounds; j) sterically hindered amines; k) metal deactivators; l) phosphites and phosphonites; m) hydroxylamines; n) nitrones; o) amine oxides; p) benzofuranones and indolinones; q) thiosynergists; r) peroxide-destroying compounds; s) polyamide stabilizers; and t) basic co-stabilizers.

[0120] The above defined polyurethane and epoxy resin compositions should comprise less than 5 wt. % of water, based on the weight of the composition, and are most anhydrous compositions. These embodiments do not preclude the compositions from either comprising organic solvent or being essentially free of organic solvent. In an interesting embodiment, each said composition may be characterized by comprising, based on the weight of the composition less than 20 wt. %, less than 10 wt. % of organic solvent.

[0121] Broadly, all organic solvents known to the person skilled in the art can be used as a solvent but it is preferred that said organic solvents are selected from the group consisting of: esters; ketones; halogenated hydrocarbons; alkanes; alkenes; and, aromatic hydrocarbons. Exemplary solvents are dichloromethane, trichloroethylene, toluene, xylene, butyl acetate, amyl acetate, isobutyl acetate, methyl isobutyl ketone, methoxybutyl acetate, cyclohexane, cyclohexanone, dichlorobenzene, diethyl ketone, di-isobutyl ketone, dioxane, ethyl acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoethyl acetate, 2-ethylhexyl acetate, glycol diacetate, heptane, hexane, isobutyl acetate, isooctane, isopropyl acetate, methyl ethyl ketone, tetrahydrofuran or tetrachloroethylene or mixtures of two or more of the recited solvents.

[0122] To form a compositionsuch as a coating, adhesive or sealant compositionthe elements of the composition are brought together and mixed under conditions which inhibit or prevent activation of the latent catalyst. As such, it is preferred that the epoxy resin or polyisocyanate elements and the curative or active hydrogen bearing elements are not mixed by hand but are instead mixed by machine in pre-determined amounts under anhydrous conditions without intentional UV-irradiation. For instance, for small-scale applications in which volumes of less than 1 liter will generally be used, the composition may be formed by co-extrusion of the elements of the composition from a plurality of side-by-side double or coaxial cartridges through a closely mounted static or dynamic mixer. For larger applications, the elements of the composition may be supplied via pipelines to a mixing apparatus which can ensure fine and highly homogeneous mixing of inter alia the latent catalyst and the reactive elements in the absence of moisture and under limited irradiation.

[0123] The curable compositions according to the invention should have a viscosity in mixed form of 100 to 3000 mPa.Math.s, 100 to 1500 mPa.Math.s, as measured at a temperature of 20 C. and determined immediately after mixing, for example, up to two minutes after mixing.

[0124] The compositions of the present invention may be applied to a given substrate by conventional application methods such as: brushing; roll coating using, for example, a 4-application roll equipment where the composition is solvent-free or a 2-application roll equipment for solvent-containing compositions; doctor-blade application; printing methods; and, spraying methods, including but not limited to air-atomized spray, air-assisted spray, airless spray and high-volume low-pressure spray. For coating and adhesive applications, it is recommended that the compositions be applied to a wet film thickness of from 10 to 500 m. The application of thinner layers within this range is more economical and provides for a reduced likelihood of thick cured regions that mayfor coating applicationsrequire sanding. However, great control must be exercised in applying thinner coatings or layers so as to avoid the formation of discontinuous cured films.

[0125] Subsequent to their application, the compositions according to the present invention may typically be activated in less than a minute, and commonly between 1 and 20 secondsfor instance between 3 and 12 secondswhen irradiated using commercial UV curing equipment. Before UV activation they additionally demonstrate a long pot life, typically of at least 60 minutes and commonly of at least 90 or 120 minutes. The pot life shall be understood herein to be the time after which the viscosity of a mixture at 20 C. will have risen to more than 50,000 mPas.

[0126] The irradiating ultraviolet lightacting as an external stimulus for the latent catalystshould typically have a wavelength of from 150 to 600 nm and a wavelength of from 200 to 450 nm. Useful sources of UV light include, for instance, extra high pressure mercury lamps, high pressure mercury lamps, medium pressure mercury lamps, low intensity fluorescent lamps, metal halide lamps, microwave powered lamps, xenon lamps, UV-LED lamps and laser beam sources such as excimer lasers and argon-ion lasers.

[0127] The amount of radiation necessary to cure an individual composition will depend on a variety of factors including the angle of exposure to the radiation, the thickness of a coating layer and the volume of a mold where, for instance, the composition is to be employed as a matrix of a composite material. Broadly however, a curing dosage of from 5 to 5000 mJ/cm.sup.2 may be cited as being typical: curing dosages of from 50 to 500 mJ/cm.sup.2, such as from 50 to 400 mJ/cm.sup.2 may be considered highly effective.

[0128] The curing or hardening of the epoxy resin or polyurethane compositions of the invention typically occurs at temperatures in the range of from 10 C. to 150 C., from 0 C. to 100 C., and in particular from 10 C. to 70 C. The temperature that is suitable depends on the specific curatives and the desired hardening rate and can be determined in the individual case by the skilled artisan, using simple preliminary tests if necessary. Of course, curing at temperatures of from 5 C. to 35 C. or from 20 C. to 30 C. is especially advantageous as it obviates the requirement to substantially heat or cool the compositions from the usually prevailing ambient temperature. Where applicable, however, the temperature of the composition may be raised prior to, during or after application using conventional means.

[0129] The epoxy resin or polyurethane compositions according to the invention may find utility inter alia in: varnishes; inks; elastomers; foams; binding agents for particles and/or fibers, such as carbon fibers; the coating of glass; the coating of ceramic; the coating of mineral building materials, such as mortar, brick, tile, natural stone, lime- and/or cement-bonded plasters, gypsum-containing surfaces, fiber cement building materials and concrete; the coating and sealing of wood and wooden materials, such as chipboard, fiber board and paper; the coating of metallic surfaces; the coating of asphalt- and bitumen-containing pavements; the coating and sealing of various plastic surfaces; and, the coating of leather and textiles.

[0130] It is also considered that the compositions of the present invention are suitable as pourable sealing compounds for electrical building components such as cables, fiber optics, cover strips or plugs. The sealants may serve to protect those components against the ingress of water and other contaminants, against heat exposure, temperature fluctuation and thermal shock, and against mechanical damage.

[0131] The compositions are equally suitable for forming composite structures by surface-to-surface bonding of the same or different materials to one another. The binding together of wood and wooden materials and the binding together of metallic materials may be mentioned as exemplary adhesive applications of the present compositions.

[0132] In a particularly preferred embodiment of the invention, the epoxy or polyurethane compositions are used as solvent-free or solvent-containing lamination adhesives The present invention thus also provides a method of forming a flexible film laminate, said method comprising the steps of: a) providing first and second flexible films; b) providing a curable composition as defined hereinabove; c) disposing the curable composition on at least a portion of one surface of the first flexible film; d) joining the first flexible film and a second flexible film so that the curable adhesive mixture is interposed between the first flexible film and the second flexible film; and, e) simultaneously with or subsequent to said joining step, irradiating said adhesive mixture with ultraviolet light to cure said mixture.

[0133] The first flexible film and a second flexible film are joined so that the curable adhesive composition is interposed between the first flexible film and the second flexible film. Depending on the films used in a lamination, the UV radiation necessary to cure the adhesive mixture can be passed through one or both films or, conversely, it may be necessary to irradiate the adhesive mixture when it is accessible in the joining step, that is prior to and during the mating of the film surfaces.

[0134] In the packaging applications for which the present invention is envisaged to be particularly suitable, the first and second flexible films will typically be constituted by polyethylene, polyester, polyethylene terephthalate, oriented polypropylene, ethylene vinylacetate, poly(methylmethacrylate), polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS), co-extruded films, metal foils and the like. Obviously, if the irradiation step e) is be performed subsequent to said joining step, this restricts the films used to ones that are UV transparent. Oriented polypropylene has proven to be an excellent film in this regard because it absorbs 10% of UV radiation. In contrast, polyethylene terephthalate based films absorb c. 40% of the UV radiation from an H-bulb and are not practical candidates for the curing of the adhesives of the present invention by UV irradiation of the adhesives through the film.

[0135] The following examples are illustrative of the present invention, and are not intended to limit the scope of the invention in any way.

EXAMPLES

[0136] The following materials are used in the Examples: [0137] LIOFOL LA 6707: Polyester Polyol having an OH number of ca.135 mgKOH/g and an Mw of ca. 2600 g/mol, available from Henkel AG & Co. KGaA. [0138] LIOFOL LA 7707: NCO-pre-polymer (polyisocyanate) based on MDI, polyether polyols and castor oil, available from Henkel AG & Co. KGaA. [0139] D.E.R.331 Liquid Epoxy Resin, a reaction product of epichlorohydrin and bisphenol A, available from The Dow Chemical Company.

Example 1: Synthesis of PEG-dilm-Ant-BPh.SUB.4

[0140] This Example relates to the multi-stage synthesis of the following quaternary nitrogen compound (above identified as PEG-dilm-Ant-BPh.sub.4).

##STR00003##

Stage 1.1: Synthesis of PEG-dilm

[0141] In a 1-necked 100 mL flask equipped with a magnetic bar, 8.6 g of poly(ethylene glycol) diacrylate (12.3 mmol), 50 mL of chloroform and 1.8 g of imidazole (27.0 mmol) were introduced. The mixture was heated up to 80 C. and left, under stirring, for 48 hours. The solvent was then evaporated under reduced pressure. The crude product obtained was dissolved in the minimum amount of dichloromethane (10 mL) and precipitated in 100 mL of diethyl ether at 0 C. three times. The light orange oil obtained was isolated and dried under reduced pressure.

Stage 1.2: Synthesis of PEG-dilm-Ant-Cl

[0142] In a 2-necked 50 mL flask equipped with a magnetic bar, 0.70 g of 9-chloromethyl anthracene (3.10 mmol), 10 mL of dichloromethane and 1.0 g of PEG-dilm from Stage 1.1 (1.41 mmol) were introduced under flux of argon. The mixture was left, under stirring, at room temperature for 48 hours. The solvent was then evaporated under reduced pressure. The crude product obtained was dissolved in the minimum amount of dichloromethane (1 mL) and precipitated in 20 mL of diethyl ether at 0 C. three times. The brown oil obtained was isolated and dried under reduced pressure.

Stage 1.3: Synthesis of PEG-dilm-Ant-BPh.SUB.4

[0143] In a 1-necked 50 mL flask equipped with a magnetic bar, 0.40 g of PEG-dilm-Ant-Cl from Stage 1.2 (0.32 mmol) was dissolved in 10 mL of methanol. Then, 0.22 g of sodium tetraphenyl borate (0.64 mmol), previously dissolved in the minimum amount of methanol (1 mL), was added dropwise to the flask. A precipitate was formed immediately and the mixture was left, under stirring, at room temperature overnight. The solid was isolated by filtration and rinsed with methanol several times. The orange pale powder obtained was dried under reduced pressure. The overall yield of this powder was 56%.

Example 2: Synthesis of PEG-Im-Ant-BPh.SUB.4

[0144] This Example relates to the multi-stage synthesis of the following compound (above identified as PEG-Im-Ant-BPh.sub.4).

##STR00004##

Stage 2.1: Synthesis of PEG-Im

[0145] In a 3-necked 250 mL flask equipped with a magnetic bar, 36 g of poly(ethylene glycol) methyl ether acrylate (75.0 mmol), 90 mL of chloroform and 5.1 g of imidazole (75.0 mmol) were introduced. The mixture was heated up to 80 C. and left, under stirring, for 48 hours. The solvent was then evaporated under reduced pressure. The crude product obtained was dissolved in the minimum amount of dichloromethane (40 mL) and precipitated in 400 mL of diethyl ether at 0 C. three times. The light orange oil obtained was isolated and dried under reduced pressure.

Stage 2.2: Synthesis of PEG-Im-Ant-Cl

[0146] In a 3-necked 250 mL flask equipped with a magnetic bar, 9.1 g of 9-chloromethyl anthracene (40.1 mmol), 30 mL of dimethylformamide and 22 g of PEG-Im from Stage 2.1 (40.1 mmol) were introduced under flux of argon. The mixture was subsequently heated up to 70 C. and left overnight under stirring. The mixture was used without further purification in the next stage (2.3): it could, alternatively, have been precipitated in 400 mL of diethyl ether at 0 C. three times.

Stage 2.3: Synthesis of PEG-Im-Ant-BPh.SUB.4

[0147] The reaction mixture of Stage 2.2 (PEG-Im-Ant-Cl) was cooled down to room temperature and 30 mL of methanol were added. Then, 13.7 g of sodium tetraphenyl borate (40.1 mmol), previously dissolved in the minimum amount of methanol (15 mL), was added dropwise to the flask. The reaction mixture was heated up to 70 C. for 4 hours and, after subsequent cooling, was left at room temperature overnight under stirring. The solvent was then evaporated under reduced pressure and the crude product was dissolved in tetrahydrofuran. The precipitated salts were removed by filtration through diatomaceous earth and a transparent solution was obtained. After removing a portion of the solvent such that the product was dissolved in the minimum amount of tetrahydrofuran, the product was precipitated in 400 mL of diethyl ether and the brown oil obtained was dried under reduced pressure. The overall yield of this oil was 80%.

Example 3: Synthesis of PEG-Im-kBn-BPh.SUB.4

[0148] This Example relates to the multi-stage synthesis of the following compound (above identified as PEG-Im-kBn-BPh.sub.4).

##STR00005##

Stage 3.1: Synthesis of PEG-Im-kBn-Br

[0149] In a 3-necked 100 mL flask equipped with a magnetic bar, 7 g of 2-bromoacetophenone (35.0 mmol), 20 mL of dimethylformamide and 19.2 g of PEG-Im as obtained in Stage 2.1 (35.0 mmol) were introduced under flux of argon. The mixture was subsequently heated up to 70 C. and left overnight under stirring. The mixture can be used without further purification in the next stage (3.2): the product could alternatively have been first precipitated in 400 mL of diethyl ether at 0 C. three times.

Stage 3.2: Synthesis of PEG-Im-kBn-BPh.SUB.4

[0150] The reaction mixture 3.2 (PEG-Im-kBn-Br) was cooled down to room temperature and 30 mL of methanol was added. Then, 12.0 g of sodium tetraphenyl borate (35 mmol), previously dissolved in the minimum amount of methanol (10 mL), was added dropwise to the flask. The reaction mixture was heated up to 70 C. for 4 hours and, after subsequent cooling, was left at room temperature overnight under stirring. The solvent was evaporated under reduced pressure and the crude was dissolved in tetrahydrofuran. The precipitated salts were removed by filtration through diatomaceous earth and a transparent solution was obtained. After removing a portion of the solvent such that the product was dissolved in the minimum amount of tetrahydrofuran, the product was precipitated in 400 mL of diethyl ether and the brown oil obtained was dried under reduced pressure. The overall yield of this oil was 85%.

Example 4: Synthesis of PPG-b-PEG-diGUA-Ant-BPh4

[0151] This Example relates to the multi-stage synthesis of the following compound (above identified as PPG-b-PEG-diGUA-Ant-BPh.sub.4).

##STR00006##

Stage 4.1: Synthesis of PPG-b-PEG-diGUA

[0152] In a 3-necked 250 mL flask equipped with a magnetic bar, 35 g of polyethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (17.5 mmol), 80 mL of Toluene and 5.3 g of anhydrous triethylamine (52.5 mmol) were introduced. Then, 7.3 g of p-Toluenesulfonyl chloride (38.5 mmol) was added to the flask, the reaction mixture was left to stir at room temperature for 30 min and then heated up to 60 C. for 48 hours. Once the reaction was finishedthe progress of the reaction being followed by NMRthe mixture was allowed to cool down to room temperature. The cooled mixture was added, via cannula equipped with filter paper, to a 3-necked 250 mL flask containing 4 g of KOH (70 mmol), 5 g of 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (35 mmol) and 40 mL of anhydrous dimethylformamide. The reaction mixture was left overnight at 80 C. under stirring.

Stage 4.2: Synthesis of PPG-b-PEG-diGUA-Ant-Cl

[0153] In a 3-necked 250 mL flask equipped with a magnetic bar, 34 g of PPG-b-PEG-diGUA from Stage 4.1 (30 mmol), 40 mL of dimethylformamide and 7.1 g of 9-chloromethyl anthracene were introduced. The mixture was left to stir overnight at 60 C. and, after being cooled down to room temperature, it was used without further purification in the next stage (4.3).

Stage 4.3: Synthesis of PPG-b-PEG-diGUA-Ant-BPh.SUB.4

[0154] To the flask containing the product obtained in Stage 4.2 (PPG-b-PEG-diGUA-Ant-Cl), 40 mL of methanol was added. Then, 10.3 g of sodium tetraphenyl borate (30 mmol), previously dissolved in the minimum amount of methanol (10 mL), was added dropwise to the flask. The reaction mixture was heated up to 70 C. for 4 hours and, after cooling down, was left at room temperature overnight under stirring. The solvent was evaporated under reduced pressure and the crude product was dissolved in tetrahydrofuran. The precipitated salts were removed by filtration through diatomaceous earth and a transparent solution was obtained. After removing the solvent, the product was precipitated in 400 mL of diethyl ether and the brown oil obtained was dried under reduced pressure. The overall yield of this oil was 62%.

Example 5: Synthesis of PPG-b-PEG-dilm-Ant-BPh4

[0155] This Example relates to the multi-stage synthesis of the following compound (above identified PPG-b-PEG-dilm-Ant-BPh4).

##STR00007##

Stage 5.1: Synthesis of PPG-b-PEG-dilm

[0156] In a 3-necked 250 mL flask equipped with a magnetic bar, 35 g of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (17.5 mmol), 100 mL of dichloromethane and 7.1 g of anhydrous triethylamine (70 mmol) were introduced. Then, the reaction was cooled down at 0 C. in an ice bath and 3.80 g of acryloyl chloride (42 mmol) was slowly added to the flask. The reaction mixture was left to stir at 0 C. for 30 minutes and then left at room temperature for 2 hours. Once the reaction was finished (as monitored by NMR), the ammonium salt precipitated was filtered off and the filtrate was washed with 1 M NaOH solution (three times), with a saturated solution of NaHCO.sub.3(three times) and with brine (three times). The final solution was dried with MgSO.sub.4 and the solvent was evaporated under reduced pressure.

[0157] The crude product thus obtained was dissolved in 100 mL of chloroform in a 250 mL round bottom flask and 2.5 g of imidazole (36.8 mmol) was added. The mixture was heated at 80 C. overnight. After that, the crude product was used in the next step without further purification.

Stage 5.2: Synthesis of PPG-b-PEG-dilm-Ant-Cl

[0158] To the 250 mL round bottom flask containing the reaction mixture from stage 5.1 (PPG-b-PEG-dilm), 35 mL of dimethylformamide and 7.5 g of 9-chloromethyl anthracene (33 mmol) were added. The mixture was left to stir overnight at 60 C. and, after cooling down to room temperature, the mixture was used without further purification in the next stage (5.3).

Stage 5.3: Synthesis of PPG-b-PEG-dilm-Ant-BPh.SUB.4

[0159] To the flask containing the product obtained in stage 5.2 (PPG-b-PEG-dilm-Ant-Cl), 35 mL of methanol was added. Then, 12 g of sodium tetraphenyl borate (35 mmol), previously dissolved in the minimum possible amount of methanol (10 mL), was added dropwise to the flask. The reaction mixture was heated up to 70 C. for 4 hours and, after subsequent cooling down, was left at room temperature overnight under stirring. The solvent was evaporated under reduced pressure and the crude product was dissolved in tetrahydrofuran. The precipitated salts were removed by filtration through diatomaceous earth and a transparent solution was obtained. After removing the solvent, the product was precipitated in 400 mL of diethyl ether and the brown oil obtained was dried under reduced pressure. The overall yield of this oil was 45%.

[0160] In the below mentioned Example 6, the progress of the described curing reactions was monitored using Fourier transform infrared spectroscopy (FTIR) in conjunction with Attenuated Total Reflection (ATR), hereinafter FTIR (ATR). For each FTIR absorption spectrum, the carbonyl peak was identified at around 1700 cm.sup.1 whilst the disappearance of the isocyanate peak at around 2270 cm.sup.1 was monitored. [The absorption peak of the carbonyl group does shift to a slightly higher wavenumber as the polyisocyanate content of the adhesive mixture declines.] Specifically, the ratio of the area of the peak at 2270 cm.sup.1 to the peak at around 1700 cm.sup.1 was quantified, the decline of which quantity over time correlates to the consumption of the polyisocyanate in the polyaddition reaction.

Example 6: Two Component (2K) Polyurethane Composition

[0161] 1.5 g of polyol (LA 6707) was mixed with 45 mg of PEG-b-PPG-dilm-Ant-BPh.sub.4 (Example 5) diluted with 2 mL DCM. In addition, 2 g of isocyanate (LA 7707) was also diluted with dichloromethane and then mixed with the previous solution. The resulting adhesive mixture was placed on an aluminium foil and spread with a coating bar (No. 4). The solvent was allowed to evaporate and the coating heated for 30 seconds at 50 C. with a heat gun. The coating average over the aluminium foil was around 9 g/m.sup.2. The coated aluminium foil sample was designated as CF1.

[0162] For comparative analysis, a further portion of the above adhesive mixture was prepared but without the added latent catalyst. This adhesive mixture was similarly applied to aluminium foil and the resultant coated aluminium foil sample was designated as CF2.

[0163] The coated aluminium foil samples were then permitted to cure under the following conditions:

[0164] CF1: UV irradiation at a curing dosage of 300 mJ/cm.sup.2

[0165] CF2: Ambient conditions without irradiation

The results of the FTIR (ATR) monitoring of the curing of the adhesive mixtures are shown in Table 1 herein below.

TABLE-US-00001 TABLE 1 CF1 CF2 Time (min) Peak Ratio Time (min) Peak Ratio 7 10.6 6 12.1 10 10.0 9 12.1 27 7.2 26 10.9 35 6.7 35 10.7 53 5.6 52 9.9 68 4.8 68 9.0 108 4.3 107 7.8 145 3.3 145 7.3

Example 7: Two Component (2K) Epoxy Thiol Curable Composition

[0166] In a glass vial were mixed 1.00 g of epoxy resin (D.E.R 331), 0.50 g of thiol-based hardener (1,8-Dimercapto-3,6-Dioxaoctane, DMDO) and 50 mg of latent catalyst from Example 4 (PEG-b-PPG-diGUA-Ant-BPh4). The mixture was homogenized by stirring for 1 minute with a spatula.

[0167] To study the activity and latency of the catalyst in the mixture, five samples from the mixture were treated in the following manner:

[0168] S1: The sample was irradiated for 5 seconds with UV light

[0169] S2: The sample was irradiated for 20 seconds with UV light

[0170] S3: The sample was post-cured at 80 C. for 1 hour after 5 seconds of irradiation

[0171] S4: The sample was post-cured at 80 C. for 1 hour without irradiation

[0172] S5: The sample was neither irradiated nor thermally treated

[0173] The curing profiles of the treated samples were studied by Differential Scanning calorimetry (DSC) in order to determine the efficacy of the latent catalyst. The following DSC cycles were used: i) 1.sup.st Heating from 20 C. to 250 C. at 10 C./min; ii) Cooling from 250 C. to 20 C. at 10 C./min; and, iii) 2.sup.nd Heating from 20 C. to 250 C. at 10 C./min.

The curing profiles are described in Table 2 herein below of which profiles the respective glass transition temperatures (Tg) were determined from the 2.sup.nd heating cycle.

TABLE-US-00002 TABLE 2 Resin System Sample Peak Max. ( C.) H (J/g) Tg* ( C.) DER-DMDO S1 137 460 3.4 S2 135 466 6.7 S3 10 S4 179 376 10.7 S5 187 459 10.0