Abstract: A coating composition comprising(A) a film-forming polymer having functional group(s) capable of reacting with the crosslinking agent (D) hereinafter referred to and cationic or anionic functional group(s),(B) a volatile organic liquid diluent in which the polymer (A) is dissolved,(C) crosslinked polymer microparticles bearing anionic or cationic functional group(s) whose electric charge is opposite to that of the film-forming polymer, which are insoluble in the combination of the film-forming polymer (A) and the diluent (B) and are maintained in a stabilized state of dispersion therein, and(D) a crosslinking agent dissolved in the diluent (B).

Abstract: An elastomeric homopolymer or copolymer is reacted with or, in effect, grafted onto an unsaturated polyester and the reaction product or graft polymer may then be used in a thermosetting unsaturated polyester resin composition. The chemical linkage between the elastomeric polymer and the unsaturated polyester is a cyclic structure comprising 6 carbon atoms. The chemical bond is achieved by first treating the elastomeric polymer to incorporate a conjugated diolefin structure and then adding the conjugated diolefin group to an ethylenically unsaturated group in the polyester or a monomeric dienophile. When added to a monomeric dienophile, the polyester is then grafted onto the elastomeric polymer at the site of the monomeric dienophile. The chemical linkage or bonding occurs through a 4+2 Diels Alder addition.

Abstract: Storage-stable, thermally-curable, one-part epoxy resin compositions comprising a curable opoxide resin; a curative amount of an aliphatic or non-aromatic cyclic polyol having about 2 to 18 carbon atoms, at least two hydroxy groups of said polyol being primary or secondary, and said polyol being free of strong acid groups, and free of electron-withdrawing substituents and large groups which cause steric hindrance in the .alpha.-position in relation to the carbon atoms attached to the methylol groups of the polyol; and a catalytic amount of an imidazole compound.

Abstract: Flexible thermoplastic epoxy resins are prepared by reacting (1) an advanced epoxy resin prepared by reacting a mixture of an aromatic based epoxy resin and an aliphatic based epoxy resin with a polyhydric phenol in the presence of an advancement catalyst with (2) a monocarboxylic acid or anhydride thereof; reacting the resultant product with a mixture of an aromatic based epoxy resin and a monofunctional material reactive with vicinal epoxy groups; and reacting the resultant product with a carboxyl terminated elastomer. These resins are particularly useful in formulating pavement marking paints.

Abstract: Heat curable compositions of reinforcing fibers (filaments), a thermosetting prepolymer or prepolymers and an effective amount of a curing agent or agents in which the fibers have been precoated with a fiber- and matrix resin-reactive elastomer are described. The compositions are useful to form composites of high fracture toughness and compressive strength which, in turn, can be formed into structural members such as aircraft parts. Processes for applying an elastomer coating to fiber tapes, fabrics and rovings are also described.

Abstract: Dieneophile functional modified aminoepoxy resins are disclosed, which resins are the reaction product of (i) diepoxide reactant, (ii) amine functional dieneophile chain extending reactant, (iii) optionally, end-capping reactant such as monohydroxy functional blocked dieneophile, (iv) hydroxy functional secondary amine modifying agent, and (v) certain secondary amine terminated or carboxy terminated butadiene acrylonitrile copolymer modifying agent.

Abstract: Epoxy adhesive compositions which are suitable for use in bonding metal and SMC parts to other metal and SMC parts comprise, in admixture, an epoxy resin, the adduct of an epoxy resin and a reactive (meth)acrylonitrile/butadiene rubber and a mixture of Lewis acid complexes having different cure times. The adhesive can be cured at elevated temperatures in 5 minutes or less.

Abstract: A coating composition useful as a finish for flexible and rigid substrates of automobiles and truck bodies and contains a binder and an organic carrier; wherein the binder containsA. an amine polymer of polymerized ethylenically unsaturated monomers and a polymerized constituent of the formula: ##STR1## where R.sup.1 is H or CH.sub.3, R.sup.2 is an aliphatic group and R.sup.3 is a cycloaliphatic group and the polymer has a molecular weight of about 2,000 to 50,000 andB. an epoxy resin.

Abstract: A crosslinkable composition of matter is provided, which comprises first and second chain extended diepoxide resins, one or both of which are modified by reaction with hydroxy functional secondary amine and one or both of which are modified by reaction with certain secondary amine terminated or carboxy terminated butadiene acrylonitrile copolymer resin. The first resin, diene functional aminoepoxy resin, and the second resin, blocked dieneophile functional aminoepoxy resin, are co-reactive at elevated cure temperature. The diene functional aminoepoxy resin comprises the reaction product of diepoxide with amine functional diene chain extending reactant and, optionally, monofunctional end-capping reactant such as monohydroxy functional diene, and certain modifying agents.

Abstract: Composite laminates such as metal plate/vibration damper/metal plate, metal plate/vibration damper/metal plate/vibration damper, metal plate/vibration damper/metal plate/vibration damper/metal plate are disclosed. The vibration damper is composed of ethylene-(meth)acrylic acid salt copolymers or its modified products having a specific melting point and a particular heat of fusion. The composite laminate having at least one vibration damper exhibits excellent vibration damping performance, particularly at high temperatures.

Abstract: Described herein is a composition which contains a specific group of hardeners, an epoxy resin and a thermoplastic polymer. When combined with a structural fiber the composition produces composites which have improved impact resistance, improved tensile properties and high compressive properties.

Abstract: A process for the rapid formation of thermoset polymers by polymerizing a mixture of a polyepoxide with a polycarboxylic acid containing an alkali or alkaline earth metal cationic complex catalyst is disclosed.

Abstract: Dieneophile functional modified aminoepoxy resins are disclosed, which resins are the reaction product of (i) diepoxide reactant, (ii) amine functional dieneophile chain extending reactant, (iii) optionally, end-capping reactant such as monohydroxy functional blocked dieneophile, (iv) hydroxy functional secondary amine modifying agent, and (v) certain secondary amine terminated or carboxy terminated butadiene acrylonitrile copolymer modifying agent.

Abstract: Diene functional modified aminoepoxy resins are disclosed, which resins are the reaction product of (i) diepoxide reactant, (ii) amine functional conjugated diene chain extending reactant, (iii) optionally, end-capping reactant such as monohydroxy functional diene, (iv) hydroxy functional secondary amine modifying agent, and (v) certain secondary amine terminated or carboxy terminated butadiene acrylonitrile copolymer modifying agent.

Abstract: A resin composition comprising 100 parts by weight of a thermosetting resin and 1 to 100 parts by weight of a functional, rubbery copolymer containing among the monomer units which constitute the copolymer, at least one monomer containing a substituent selected from the group consisting of epoxy, hydroxyl, carboxyl and amino groups, said copolymer being prepared by one of three emulsion polymerization processes in which a nonionic surface active agent and/or ionic surface active agent is employed as the emulsifying agent.

Abstract: A crosslinkable composition of matter is provided, which comprises first and second chain extended diepoxide resins, one or both of which are modified by reaction with hydroxy functional secondary amine and one or both of which are modified by reaction with certain secondary amine terminated or carboxy terminated butadiene acrylonitrile copolymer resin. The first resin, diene functional aminoepoxy resin, and the second resin, blocked dieneophile functional aminoepoxy resin, are co-reactive at elevated cure temperature. The diene functional aminoepoxy resin comprises the reaction product of diepoxide with amine functional diene chain extending reactant and, optionally, monofunctional end-capping reactant such as monohydroxy functional diene, and certain modifying agents.

Abstract: Disclosed is a composition that includes a liquid prepolymer that is the reaction product of a monoanhydride, a cycloaliphatic epoxy, and an alcohol. Also included in the composition is a maleated polybutadiene that is a reaction product of butadiene, maleic anhydride, and an oxygen scavenger. The composition also includes a tertiary amine accelerator, a free-radical initiator, and a solvent. A prepreg is prepared from the composition by immersing a porous substrate into the composition, drying and curing to the B-stage. A laminate is prepared by forming a stack of prepregs and heating under pressure to the C-stage.

Abstract: Provides new and improved water-reducible coating compositions and methods of making them. Three preferred processes are disclosed. These differ in the manner of incorporating and chemical nature of an extender polymer.Broadly, the process of the invention is one for forming an aqueous dispersion of a fluent resinous composition ofa. a mixture in an organic solvent of(i) an ionizable graft polymer of an epoxy resin and an addition polymerized resin, the addition polymerized resin being bonded to aliphatic backbone carbon atoms of the epoxy resin by carbon-to-carbon bonds, and(ii) an extender resin;b. an aqueous vehicle, andc. an ionizing agent;the ionization present from said combined components being sufficient to establish the components as a dispersion in the aqueous vehicle, and then addition polymerizing a quantity of addition polymerizable monomer, under addition polymerizing conditions, in said aqueous dispersion, the aqueous dispersion serving as a vehicle therefor.

Abstract: An impact-resistant phenolic resin composition comprising 99 to 25% by weight of a phenolic resin and 1 to 75% by weight of a nitrile group-containing highly saturated polymer rubber whose amount of bound nitrile ranges from 10 to 60% by weight and having an iodine value not exceeding 120.

Abstract: Cured polyfunctional epoxy resins including tris(hydroxyphenyl)methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy-terminated butadiene-acrylonitrile rubber is optionally present in the pre-cure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon-reinforced composites, of these resins are disclosed and shown to have improved toughness.

Abstract: This invention relates to a thermosetting plastisol dispersion composition comprising(1) at least one copolymer of acrylonitrile-butadiene-styrene (ABS) in powder form, which is insoluble in the reactive plasticizer at room temperature and plasticizable at a temperature at or above the fluxing temperature;(2) a liquid reactive plasticizer member of the group consisting of (a) at least one epoxide resin having an average of more than one epoxide group in the molecule, (b) at least one liquid monomer, oligomer or prepolymer characterized by (1) containing at least one ethylenically unsaturated group and (2) capable of solvating the ABS at the fluxing temperature, and (c) a mixture of (a) and (b); and(3) an effective amount of either a thermal initiator or photoinitiator for plasticizers present in the composition.The plastisol dispersion after fluxing can form a thermoset sealant, coating or adhesive after the crosslinking reaction.

Abstract: A method for flexibilizing an epoxy resin is disclosed which comprises (a) preparing a dicarboxy-terminated prepolymer by reacting a carboxylic anhydride with a polybutadiene having a minor amount of pendant vinyl groups at a temperature from about 125.degree. to about 140.degree. F.; (b) reacting the prepolymer with an excess of liquid epoxy resin at a temperature from about 180.degree. to about 200.degree. F.; (c) adding a vinyl monomer in an amount of about 2% to about 25% of the mixture; and (d) adding epoxy and vinyl polymerization catalysts to cure the mixture.

Abstract: An improved curable epoxy resin composition comprising an epoxy resin and vulcanized rubber particles having a particle size of 0.5 to 30.mu. which are obtained by vulcanizing a dispersion of fine particles of a liquid rubber incompatible with the epoxy resin in the epoxy resin with a vulcanizing agent, and a method for the preparation of the same. The curable epoxy resin composition has excellent flexibility, mechanical strength and peel strength when cured with a curing agent, and is useful as an adhesive, coating material or molding material.

Abstract: Disclosed is a water based thermosetting epoxy composition of a water compatible epoxy resin, about 5 to about 35% based on total solids of a water polymerized impact modifier in a water based latex, about 1.5 to about 7% based on the weight of the epoxy resin of a water compatible epoxy hardener, up to about 0.3% based on the weight of the epoxy resin of a catalyst, and sufficient water to provide a viscosity of about 100 to about 400 centipoises. The compositions are used to prepare high impact strength, high damping laminates.

Abstract: Structural adhesive systems having improved heat resistance comprising a solution or dispersion of a polymeric material in a monomer copolymerizable therewith, an unsaturated organophosphorus partial ester and an epoxy resin are disclosed.

Abstract: Rubbery polymer compositions, e.g. based on chlorobutyl rubber, having improved adhesion to mineral substrates such as glass or metal, are produced by a stepwise reaction sequence. In a first stage the rubbery polymer is reacted with a reactive silane such as an amino trialkoxy silane, in a second stage the product is mixed with an epoxy resin, and in a third stage a further amount of reactive silane is reacted with the epoxy containing compound.

Abstract: A resin composition comprising (A) a polymer having, in the molecule, at least two groups represented by the following structural formula (I): ##STR1## wherein R.sub.1 is isopropyl, sec-butyl, tert-butyl, a C.sub.5-20 alkyl group, a C.sub.3-20 cycloalkyl group, a C.sub.5-20 alkenyl group, a C.sub.3-20 hydroxyalkyl group, a C.sub.5-20 alkoxyalkyl group, a C.sub.3-20 aminoalkyl group, a C.sub.6-20 aryl group or a C.sub.6-20 arylalkyl group, and n is 0, 1 or 2, and (B) a polymer having an electron attractive group and an .alpha.,.beta.-ethylenic double bond adjacent thereto. Though said composition is stable at room temperature, it is crosslinked and cured at high temperatures because the amino group of the polymer (A) adds to the double bond of the polymer (B). Accordingly, said resin composition is suitable for use as a cathodic electrocoating material.

Abstract: The present invention relates to a room temperature curable epoxy resin adhesive composition having excellent T-peel strength, comprising an epoxy resin containing more than one epoxy group in a molecule on an average, and a hardener in the form of a polyamide-amine, which is obtained from reaction of polyamine with diene rubber having carboxyl terminal groups and other compound having carboxyl groups.

Abstract: A process for the preparation of moldings, in particular resilient elements, which by virtue of a densified surface zone with substantially closed cells, have only a low water absorption, wherein a mixture comprising:(a) 100 parts by weight of an NCO-containing prepolymer, having an NCO content of from 3 to 6% by weight and based on organic diisocyanates and substantially linear polyester-polyols or polytetramethylene ether glycol,(b) from 0.5 to 1.6 parts by weight of water,(c) one or more catalysts, preferably a tertiary amine, in an amount of from 0.01 to 2.0 parts by weight and(d) assistants, with or without additives, is reacted in a closed mold, while undergoing densification, the surface temperature of the inner wall of the mold being from 50.degree. to 70.degree. C.

Abstract: A process is provided for coating a substrate by applying to a substrate an aqueous coating composition that comprises (a) an aqueous dispersion of a film forming polymer having a minimum film forming temperature not higher than 45.degree. C.; (b) a solid, particulate polymer having a softening temperature in the range of 45.degree. to 260.degree. C. and an average particle size in the range of 2 to 400 .mu.m and (c) a solid, rubberlike polymer having an average particule size in the range of 1 to 500 .mu.m, the resulting coating being cured at a temperature of 70.degree.-260.degree. C. The invention also relates to the liquid aqueous coating composition to be used in said process.

Abstract: One-component systems which are stable on storage and can be converted to crosslinked epoxide resins on heating and which contain a crystalline epoxide resin with, on average, more than one epoxide group per molecule and a melting point between 40.degree. and 150.degree. C., and, homogeneous distribution, a curing catalyst.

Abstract: A water-absorbing rubber composition comprising (A) a 1,3-diene rubber with a crystal or glass region content as measured at an ordinary temperature of 5-50% and (B) a highly water-absorbing resin dispersed in the said rubber, the said highly water-absorbing resin being a product of crosslinking of a polymer which contains as monomer component thereof at least 40 mole percent of an .alpha.,.beta.-unsaturated compound containing 1 or 2 groups each selected from the class consisting of a carboxyl group and a group convertible to a carboxyl group with at least one crosslinking agent selected from the class consisting of a polyfunctional epoxy compound and a polyamine, the resin being in the form of a powder capable of passing through a 20-mesh Tyler screen and absorbing 20-500 times its own weight of distilled water. The composition can absorb water rapidly and produce a high swelling pressure, and has good durability in the swollen state.

Abstract: Provides new and improved water-reducible coating compositions and methods of making them. Three preferred processes are disclosed. These differ in the manner of incorporating and chemical nature of an extender polymer.Broadly, the process of the invention is one for forming an aqueous dispersion of a fluent resinous composition ofa. a mixture in an organic solvent of(i) an ionizable graft polymer of an epoxy resin and an addition polymerized resin, the addition polymerized resin being bonded to aliphatic backbone carbon atoms of the epoxy resin by carbon-to-carbon bonds, and(ii) an extender resin;b. an aqueous vehicle, andc. an ionizing agent;the ionization present from said combined components being sufficient to establish the components as a dispersion in the aqueous vehicle, and then addition polymerizing a quantity of addition polymerizable monomer, under addition polymerizing conditions, in said aqueous dispersion, the aqueous dispersion serving as a vehicle therefor.

Abstract: This invention is directed to latent thermal curing agents for epoxy resins comprising cyanourea compounds of the formula: ##STR1## wherein R is the organic moiety of a mono- or poly-isocyanate remaining after reaction of the isocyanate group or groups to form cyanourea groups and n is 1 or more, preferably 1 to 2. The epoxy-curing agent system is stable at room temperature and cures at temperatures above 100.degree. C. to form a crosslinked, solid material suitable as an adhesive, sealant or coating. The polymeric form polymerized from dicyanourea compound can be dissolved in a solvent and admixed with an epoxy resin to form a thermoset adhesive, sealant or coating on heating above 100.degree. C. The polymeric form from the combination of cyanourea and dicyanourea or dicyanourea per se dissolving in epoxy resin also forms a thermosetting adhesive, sealant or coating on heating above 100.degree. C.

Abstract: A functionally terminated polybutadiene polymer is reacted with an epoxide to produce an epoxide terminated polybutadiene. A toughening agent and a peroxide free radical initiator are mixed with the epoxy terminated polybutadiene, and upon reaction a tough thermoset resin is produced having advanced chemical, electrical, and thermomechanical properties. Particular improvements are in the resistant-to-moisture and the tensile strain-to-failure properties.

Abstract: An adhesive for floor coverings containing(a) 100 parts by weight of an aqueous polymer dispersion having a solids content of from 30% to 70% by weight of the total weight of said dispersion, the solids content consisting of synthetic resin particles of at least a bimodal particle size distribution wherein the majority of the larger particles is at least twice the size of the majority of the smaller particles and where the majority of the larger particles has a particle size distribution of from 0.5 to 3 .mu.m and the majority of the smaller particles has a particle size distribution of from 0.1 to 1 .mu.

Abstract: A moldable sound control composite is disclosed combining in itself when molded damping, barrier performance, and structural strength for use within a predetermined environment temperature range. As such, the moldable composite is not applied to other structures to damp their sound generation, but forms by itself a complete structural member having not only desirable sound reducing properties but desirable strength properties as well. The composite comprises a blend of a primary non-viscoelastic organic polymeric resinous material intended to impart structural strength to the composite, a secondary viscoelastic organic polymeric resinous material to provide damping performance, and filler material adapted to densify the composite and impart barrier performance. Optionally, at least one of the primary and secondary resinous materials may be thermosetting.

Abstract: A continuous solution polymerization process for polymerizing conjugated dienes alone or with a copolymerizable monovinylarene in the presence of a gel inhibitor employing a first stirred reactor in series with a following plug-flow tube reactor.

Abstract: A sprayable, solventless bracing composition is made from the admixture of 100 parts of bisphenol A epoxy resin, up to about 8 parts of a coloring pigment, about 0.5 to about 4 parts of a thixotropic agent, about 100 to about 200 parts of butadiene/acrylonitrile polymer, and about 20 to about 40 parts of an amine terminated curing agent.

Abstract: Described herein are stabilizers for curable compositions containing cycloaliphatic epoxides and a catalyst. A molded article produced from such a composition possesses high mechanical properties.

Abstract: Epoxy resin compositions catalyzed with combinations of diaryliodonium salts of complex halogenides and copper salt catalyst activators are rendered stable at room temperature, but fully activatable at elevated temperatures by including an effective amount of a carboxyl terminated copolymer of butadiene and acrylonitrile, a hydroxy terminated copolymer of butadiene and acrylonitrile or a mixture thereof.

Abstract: The present invention is directed to (1) an epoxy compound identified as 3,3'-tetraglycidylsulfonyldianiline (referred to herein as 3,3'-TGDDS); (2) a thermosetting composition comprising 3,3'-TGDDS and a curing agent; (3) a thermosetting composition having improved resistance to moisture and to a reduction in the glass transition temperature at elevated temperatures when cured comprising (a) the above epoxy compound, i.e., 3,3'-TGDDS, (b) a polybutadiene rubber or mixture thereof, (c) an epoxy curing agent such as 4,4'-diaminodiphenylsulfone, (d) a free radical initiator and esterification catalyst for the polybutadiene rubber; and (4) a carbon fiber/rubber modified epoxy composite prepared from the thermosetting composition of (3).The 3,3'-TGDDS when melted and admixed with the polybutadiene rubber in a solventless system forms a homogeneous mixture which is stable for extended periods.

Abstract: The foaming of resinous insulating materials under vacuum is substantially reduced by adding to the material a polydiene having primarily vinyl unsaturation.

Abstract: Molded objects are formed from rubber and glass products, e.g. discarded glass and rubber, by grinding the rubber and glass into small particles and then melting them in separate kilns. The melted glass and rubber are then mixed together in various proportions, i.e. 20-80% by volume of the glass being added to the rubber. An epoxy resin in an amount of 0.5-1.5% is added as a binder while the melt is being mixed to a uniform consistency. Before the melt can solidify, it is poured into a mold. Small quantities of water and/or sand may also be added to the melt if desired.

Abstract: A paint composition for cationic electrodeposition process comprises a producing step in which a polymer of conjugated diene having carboxyl group at molecular terminal position or a copolymer of the said conjugated diene and vinyl monomer is made to react with an epoxy resin by a type of condensate of bisphenol A - epichlorohydrin and further, the resulting reaction compound is made to react with a primary amine compound or a secondary amine compound and thereby a reaction compound (component 1) is obtained and furthermore, the said reaction compound (component 1) is made to react with a partial block isocyanate compound (component 2) and this final reaction compound is used for an ingredient of the paint composition as a film forming material.

Abstract: A powder coating composition for forming multi layer coatings comprising:(1) at least one of finely divided thermosetting addition copolymers having a glass transition temperature of 35.degree. to 75.degree. C. and comprising as comonomers a wt. % of a hardness imparting monomer and b wt. % of a softness imparting monomer based on the copolymer wherein a+b.ltoreq.60, b.ltoreq.a and b.ltoreq.20, and(2) at least one of finely divided thermosetting resinous materials having incompatibility or low compatibility with the copolymer and a substantially greater surface tension than the copolymer when melted at the same temperature and substantially differing from the copolymer in composite parameter.

Abstract: Vinylamine copolymers are disclosed. These copolymers have randomly distributed repeating units represented by the formula ##STR1## wherein Ar is optionally substituted phenyl, the substituents independently selected from C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkoxy and halo; x and y are numbers greater than zero which total 1.0, the ratio of x to y from about 0.05:0.95 to about 0.95:0.05; and n is an integer from about 14 to about 10,000. Acid addition salts of these copolymers are also disclosed, as are vinylacetamide/aromatic hydrolysis precursors and the terpolymeric vinylamine/vinylacetamide/aromatic products of partial hydrolysis. The copolymers are useful as epoxy resin-curing agents and as components of protective or decorative coatings.

Abstract: An epoxy resin composition comprising[A] a novel copolymer produced by polymerizing a polymerizable material selected from the group consisting of(a) substituted or unsubstituted dicyclopentadiene;(b) a cationically polymerizable unsaturated hydrocarbon-containing fraction obtained by distilling a cracking or reforming product of a petroleum and having a boiling point in the range of -20.degree. C. to 280.degree. C.;(c) a cationically polymerizable vinyl aromatic hydrocarbon having 8 to 10 carbon atoms;(d) a mixture of two or three of ingredients (a), (b) and (c); and(e) a mixture of any one of ingredients (a) to (d) with a cationically polymerizable unsaturated aliphatic hydrocarbon having 4 to 10 carbon atoms in the presence of a cationic polymerization catalyst with a high-boiling product having a boiling point of at least about 150.degree. C. and an oxygen content of at least 0.

Abstract: Developer mixtures comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles. The toner particles comprise a colorant and at least about 60 percent by weight, based on the weight of the toner particles, of a resin mixture comprising between about 40 and about 90 parts by weight of a styrene resin and from about 10 to about 60 parts by weight of an epoxy resin. Electrostatographic imaging processes employing said developer mixtures are also disclosed.

Abstract: An epoxy-styrene, solventless resin impregnating varnish, having an atmospheric catalyzed pot life at room temperature of at least 45 days, is made by mixing: (1) the product of the reaction of (a) 1 part of an epoxy resin mixture, comprising solid epoxy resin and liquid epoxy resin wherein the weight ratio of solid epoxy: liquid epoxy is between 1:1 to 1:10; with (b) between about 0.01 part to 0.06 part of maleic anhydride and (c) a catalyst under such conditions that the epoxy diester formed has an acid number of between about 0.5 to 3.0; with (2) a coreactive vinyl monomer; and between about 0.0003 part to 0.004 part of a room temperature stabilizer; (3) between about 0.3 part to 1.2 part of a polycarboxylic anhydride, which is soluble in the mixture of (1) and (2), and an amount of free radical catalyst that is effective to provide a catalytic effect on the impregnating varnish and to cure it at temperatures of over about 85.degree. C., and with (4) between 0.0005 part to 0.