CA1237970A - Heat activatable adhesive or sealant compositions containing encapsulants and process therefor - Google Patents

Abstract

HEAT ACTIVATABLE ADHESIVE OR SEALANT COMPOSITIONS
CONTAINING ENCAPSULANTS AND PROCESS THEREFOR

Abstract of the Invention A process for adhering two substrates which comprises contacting said substrates with a heat curable organic resin composition comprising (1) a member of the group consisting of (a) an ethylenically unsaturated compound, containing at least 2 carbon-to-carbon double bonds, i. e., a polyene, (b) an epoxy resin containing at least 2 groups, and (c) a mixture of (a) and (b);

(2) an encapsulated polymerization initiator for (1);
and optionally (3) a thermoplastic adhesive material selected from the group consisting of polyesters, polyvinyl acetals, polyvinyl chloride, polyamides, butadiene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-ethylene-butylene copolymers, ethylene-vinyl acetate copolymers, ethylene propylene diene monomer, acrylic and methacrylic acid and their esters and mixtures thereof, and applying heat thereto by radio frequency (RF) techniques including dielectric and induction heating to form a thermoset bond. When induction heating is used, ferromagnetic and/or electrically conductive particles are usually added to the composition, either per se or in encapsulated form. The process can also be used to form sealants and coatings.

Description

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BACKGROUND OF THE INVENTION
1. vie d t eye loner This invention relates to processes for forming adhesives, sealants and coatings from a heat curable composition, the catalyst portion of which is in capsules which are melted by radio frequency (RYE) dielectric or inductive techniques to release the catalyst with resultant polymerization and curing.
mu Description of the Prior Art . . .
The concept of thermosetting or cross linking resin adhesives is known in the art. Many resin adhesives which undergo an irreversible chemical and physical change and become substantially insoluble are well known.
Thermosetting adhesives comprising both condensation polymers and addition polymers are also known and examples include the urea-formaldehyde, phenol-formaldehyde and melamine-formaldehyde adhesives; epoxy, unsaturated polyester and polyurethane adhesives. More particularly, U. S. 3,723,568 teaches the use of polyepoxides and optional epoxy polymerization catalysts. U. S. 4,122,073 teaches thermosetting resin obtained from polyisocyanates, polyanhydrides and polyepoxides. Cross linking in these patents is achieved by reaction with available sites in the base polymers U. S. 4,137,364 teaches cross linking of an ethylene/vinyl acetate/vinyl alcohol terpolymer using isophthaloyl biscaprolactam or vinyl triethoxy Solon whereby cross linking is achieved before heat activation with additional crosslinkiny induced by heat after application of the adhesive. U. S. 4,116,937 teaches a further method of thermal cross linking by the use of palomino bis-maleimide class of flexible polyamides, which compounds can be hot melt extruded up to 150C and undergo cross linking at elevated temperatures ~L237St~

there above. In these latter two patents, thermos cross linking is also achieved by reactions of the particular crosslinkiny agent with available sites of the base polymers.
on substantially all of these thermosetting adhesives bond formation is dependent on the chemical cross linking reaction which in most cases is accelerated by means of heat to obtain the bond within a reasonable period of time. Further, in many cases, e. g., epoxy adhesives, two or more components must be admixed just prior to the preparation of the bond. This necessitates a fast application since the cross linking reaction begins immediately upon admixture and is irreversible. Thus there has been a desire for a one part thermosetting adhesive which can be applied and thereafter triggered to cure on command.
On the other hand, thermoplastic adhesives, which are used in the form of solutions, dispersions or solid, usually bond by purely physical means. Probably the most important means of applying thermoplastic adhesives is the hot melt method wherein bond formation occurs when the polymer melt solidifies in position between adherents.
The bonds obtained by this method reach their final strength faster than those obtained from solution type adhesives. obviously, the thermal stability of the thermoplastic resin determines its potential usefulness as a hot melt adhesive. In order for the thermoplastic to be used as a hot melt, it must also have a low melt viscosity, thus permitting application of the adhesive to the adherents at acceptable rates. Usually this means the polymer must have a low molecular weight. However, many thermoplastic materials cannot be employed as hot melts because they do not have sufficient cohesive strength at the low molecular weights required for application to a ~37~7~
substrate. For example, the low molecular weight polyolefins, especially low molecular weight, low density polyethylene, are widely used in hot melt adhesives for sealing corrugated cartons, multi wall bag seaming and the like, but they do not have sufficient strength to be used in structural applications such as plywood manufacture.
Further, they do not have sufficient heat resistance to be used for bonding components which are intermittently exposed to elevated temperatures such as under the hood -10 automotive applications. That is, thermoplastic adhesives cannot be employed where the adhesive in situ is reoccupies to elevated temperatures which will cause the adhesive to sag thereby allowing the bond to break.
In the prior art there are many two-part materials which are cured in situ at elevated temperature, e. g., epoxy and urethane resins. The curing times, however, are relatively long in many cases, thereby precluding on-line production in a continuous operation.
The curing time can be substantially reduced by heating, but such methods are rarely used due to the fact that external heating also causes substrate or adherents to be heated. In the case of heat sensitive substrates and adherents, e. 9., thermoplastics, it can cause damage or distortion thereof.
The concept ox encapsulating components in materials rupturable by heat, pressure, a combination thereof or other means is known in the art. U. S. 3,206,755 and 3,295,141 both teach electrostatic rupturing of micro capsules. U. S. 3,317,433 teaches heat rupturable capsules which may contain an adhesive activator.
U. SO 3,666,597 discloses an adhesive comprising an encapsulated catalyst which is ruptured by pressure upon application or disintegrated by dissolution.
U. S. 4,080,238 teaches a liquid adhesive having an amine activator encapsulated in pressure rupturable ~37~
micro spheres. U. S. 4,237,252 teaches a storage-stable, one-part, curable resin composition comprising I. a latent catalyst which comprises heat rupturable micro capsules hazing shell walls of a cross linked inter-facial polyurethane-polyether reaction product and liquid fills of a Lewis acid-glycerol complex, II.
a cationically curable monomer composition and III. a Lewis base scavenger.
It should be noted that in alp the above systems, where the capsules are heat rupturable, the heating is carried out by conventional means, eon g., an air oven as far as can be ascertained. Most plastic heating processes such as conductive, convective or infrared heating are surface-heating processes which need to establish a temperature within the plastic by subsequent transfer of heat to the bulk of the plastic by con-diction. In RF heating techniques including dielectric and induction heating, the heat is generated within the material and is, therefore, uniform and rapid eliminating the need for conductive heat transfer.
OBJECTS OF THE INVENTION
One object of the instant invention is to produce a one-part adhesive or sealant composition. another object of the instant involution it to produce an adhesive or sealant compost-lion which is curable in a minimum time period. Still another object is to produce an adhesive or sealant composition which is curable by radio frequency techniques such as dielectric or induction heating. Other objects will become apparent from a reading hereinafter.
SUMMARY OF THE INVENTION
The present invention is directed to a process for adhering two substrates which comprises contacting said sub-striates with a heat curable organic resin composition comprising:
(1) a member of the group consisting of (a) an ethylenically unsaturated compound, containing at least 2 carbon-to-carbon double bonds;

~237~7~
(b) an epoxy resin containing at least I C-C

groups in combination with (a);

(2) an encapsulated polymerization initiator for (1);
and

(3) a thermoplastic adhesive material selected from the group consisting of polyesters, polyvinyl acetals, polyvinyl chloride, polyamides, butadiene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrenes ethylene-butylene copolymers, ethylene-vinyl acetate copolymers, ethylene propylene dine monomer, acrylic and methacrylic acid and their esters and mixtures thereof, and applying heat thereto by radio frequency (RF) means.
The invention further provides a process for adhering two substrates which comprises contacting said substrates with a heat curable organic resin composition comprising;
(1) a member of the group consisting of (a) an ethylenically unsaturated compound, containing at least 2 carbon-to-carbon double bonds, and (b) an epoxy resin containing at least I C-C C
O
groups in combination with (a);
12) a polymerization initiator for (1); and ; (3) encapsulated ferromagnetic and/or electrically conductive particles.
PRESCRIPTION OF TOE INVENTION
The present invention is directed to a process for adhering two substrates which comprises contacting said sub-striates with a heat activatable adhesive or sealant organic resin composition comprising:

I' pa -.
.
.. . .

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(1) a member of the group consisting of (a) an ethylenically unsaturated compound, containing at least 2 carbon-to-carbon double bonds, i. e., a pylon, by an epoxy resin containing at least 2 ~C-7 groups and (c) a mixture of (a) and (b);
(2) an encapsulated thermal initiator for (1); and optionally (33 a thermoplastic adhesive material selected from the group consisting of polyesters, polyvinyl acetals, polyvinyl chloride, polyamides, butadiene-acrylonitrile copolymers, styrenes butadiene copolymers, styrene-isoprene copolymers, styrene-,ethylene~butylene copolymers, ethylene-vinyl acetate copolymers, ethylene propylene dine monomer, acrylic and methacrylic acid and their esters and mixtures thereof, and applying heat thereto by radio frequency (OF) techniques including dielectric and induction heating to form a thermoses bond. When induction heating is used, ferromagnetic and/or electrically conductive particles are usually added to the composition, either per so or in encapsulated form. However, when the adherents to be bond are metal, such particles are unnecessary as will be shown by an example hereinafter The process can also be used to form sealants and coatings In the instance when the ethylenically unsaturated compound is an acrylate, i. e., an acrylate terminated pylon, of the formula:
O
SHUCKS ) nil R

, , .

~2~3~

wherein R is H or an alkyd containing 1 to 12 carbon atoms, Al is an organic moiety and n is at least 2, the compound can be made by various reactants and methods. One of these acrylate terminated materials is a polyether polyol urethane polyacrylate formed by reacting a puller polyol with a polyisocyanate and a hydroxyalkyl acrylate. Another material may be a polyester polyol urethane polyacrylate wormed by reacting a polyester polyol with a polyisocyanate and a hydroxyalkyl acrylate. Still another material in this category is an epoxy acrylate formed by reacting a diepoxide with acrylic acid. Yet another acrylate terminated material operable herein is a polyether or a polyester acrylate formed by end-capping a polyether polyol or polyester polyol with acrylic acid or acryoyl chloride. Yet another acrylate terminated material operable herein is a urethane polyacrylate formed by end-capping a doesn't with a hydroxyalkyl acrylate.
Examples of acrylate terminated materials include, but are not limited to, 1,3-~-ltylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, polyethylene glycol 200 diacrylate, tetraethylene glycol diacrylate, triethylene glycol diacrylate, pentaerythritol tetraacrylate, tripropylene glycol diacrylate, ethoxylated bisphenol-A diacrylate, trimethylolpropane triacrylate, di-trimethylol propane tetraacrylate, triacrylate of tris~hydroxyethyl)-isocyanate, dipentaerythritol hydroxypentaacrylate, pentaerythritol triacrylate, ethoxylated trimethylol-propane triacrylate, triethylene glycol dimethacrylate~ethylene glycol dimethacrylate~ tetraethylene glycol dimethacrylate, polyethylene glycol-200 dimethacrylate, hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol-600 dimethyacrylate, I

battalion glycol dimethacrylate, ethoxylated bisphenol-A dimethacrylate, trimethylolpropane trimethacrylate, diethylene glycol dimethacrylate, 1,4-butanediol diacrylate, diethylene glycol dimeth-acrylate, pentaerythritol tetramethacrylate, glycerindimethacrylate, trimethylolpropane dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol dimethacrylate and pentaerythritol diacrylat2.
In the case where the ethylenically unsaturated compound is an unsaturated polyester conventional unsaturated polyesters can be used, such as those described in Kirk-Othmer, Encyclopedia of Chemical Technology, end Ed., Vol. I ppm 791-839, That is, conventional unsaturated polyesters operable herein are a class of soluble linear, low molecular weight (low) macromolecules which contain both carboxylic ester groups and carbon carbon double bonds as recurring units along the main chain. These resins are usually prepared by condensation of (a) ethylenically unsaturated dicarboxylic acids or androids to impart the unsaturation, (b) saturated dicarboxylic acids to modify the resin and (c) dills.
They are represented by the structural formula O o O O
0 n ( R-O-C-R I I I ) x ( R-O-C -CH=CH KIWI ) y wherein R and R' are alkaline or Arlene radicals in the dill and saturated acid respectively, and x and y are variable numbers which depend upon the composition and condensation conditions. Polyester alkyds are diluted to a fluid state with styrenes methyl methacrylate or other vinyl monomer. These mixtures are capable of very rapid ,, Jo ,.

copolymerization to produce strong solids. This free-radical-initiated reaction proceeds via an addition mechanism involving the double bonds of both materials and leads to formation of a highly cross linked structure.
Conventional general-purpose unsaturated polyesters usually consist of varying ratios of phthalic android and malefic android esterified with dills such as propylene glycol, dipropylene glycol, diethylene glycol or mixtures of glycols. When malefic android is used, care must be paid to ensure isomerization of the Malta to fumarate. alto can be isomerized to fumarate - catalytically or by the application of heat. However, use of isomerization catalysts can lead to cross linking or other undesirable effects on the product. Fortunately, the polyesterification reaction is normally carried out at 200C or slightly higher, and at these temperatures isomerization is concurrent with polyesterification.
Typical polyester cook times range from 6 to 16 hours at temperatures from 1~0C to as high as 230C. Reaction temperatures much above 220C can be detrimental, leading to side reactions and poor color of the product.
Generally substitution of fumarate for Malta as the unsaturated portion leads to hither flexural strength and modulus, higher hardness values, higher heat distortion temperatures and better chemical resistance in the cured systems. However, faster polymerization rates are also obtained. These differences can be equated to a higher cross link density from the fumarate unsaturation due to the more facile copolymerizability with styrene-t~pe I monomers.
Acid catalysts such as sulfuric acid or Tulane sulfonic acid increase the rate of both esterification and isomerization, but usually cause color formation and other detrimental side reactions. For this reason catalysts are ,: , ~3~7~
generally not used in high-temperature reactions.
however, metal salts or organometallic compounds are used as catalysts for direct esterification. Numerous metal salts have been used for catalyst action including, but not limited to, tetrabutyl or tetraoctyl titan ate or zircon ate or stuns oxalate in combination with sodium and zinc acetates.
The epoxy resin to be used in the composition of the invention comprises those materials possessing at least two epoxy, i.e., o C -C I, groups. These compounds may be saturated or unsaturated, lo aliphatic, cycloaliphatic, aromatic or heterocyclic and may be substituted with substituents~ such as chlorine, hydroxyl groups, ether radicals and the like.
The term "epoxy resin" when used herein and in the appended claims contemplates any of the conventional monomeric, dim Eric, oligomeric or polymeric epoxy materials containing a plurality, at least 2, epoxy functional groups. Preferably, they will be members of classes described chemically as (a) an epoxidic ester having two epoxycycloalkyl groups; (b) an epoxy resin prepolymer consisting predominately of the monomeric diglycidyl ether of bisphenol-A; (c) a polyepoxidized phenol novolak or crossly novolak; (d) a polyglycidyl ether of a polyhydric alcohol; (e) diepoxide of a cycloalkyl or alkylcycloalkyl hydrocarbon or ether; or (f) a mixture of any of the foregoing. To save unnecessarily detailed description, reference is made to the Encyclopedia of Polymer Science and Technology, Vol. 6, 1967~ Intrusions Publishers, New York, pages 209-271 _ 10 i I

Suitable commercially available epoxidic esters are preferably, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclo-hexanecarboxylate (Union Carbide ERR 4221, Cuba Geigy SUE); as well as bis(3,4-epoxy-6-methylcyclohexyl-methyl)adipate (Union Carbide ERR 4289); andbis(3,4-epoxycyclohexylmethyl)adipate (Union Carbide ERR
4299).
Suitable commercially available diglycidyl ethers of bisphenol-A are Cuba Geigy Araldite 6010, Dow Chemical DYER
331, and Shell Chemical Eon 828 and 826.
A polyepoxidized phenol formaldehyde ~ovolak prepolymer is available from Dow Chemical DEN 431 and 438, and a polyepoxidized crossly formaldehyde novolak prepolymer is available from Ciba-Geigy Araldite 538.
A polyglycidyl ether of a polyhydric alcohol is available from Cuba Geigy, based on butane-1,4-diol, Araldite RD-2; and from Shell Chemical Corp., based on *

glycerine, upon 812.
A suitable diepoxide of an alkylcycloalkyl hydrocarbon is vinyl cyclohexene dioxide, Union Carbide ERR 4206, and a suitable diepoxide of a cycloalkyl ether is bist2,3-epoxycyclopentyl)-ether, Union Carbide ERR 0400.
other examples include the epoxidized esters of the polyethylenically unsaturated monocarboxylic acids, such as epoxidized linseed, soybean, purl, oiticica, lung, walnut and dehydrated castor oil, methyl linoleate, bottle linoleate, ethyl 9,12-octadecadieno~te, bottle yule octadecatrienoate~ bottle eleostearate, monoglycerides of lung oil fatty acids, monoglycerides of soybean oil, sunflower, rhapsody, hemp seed, sardine, cottonseed oil and the like.
In most instances the polymerization initiators require heating to their disassociation temperature by RF
techniques in order to initiate the curing reaction.
* Trademark , I;
J

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However, some initiators, e. g., certain peroxides with or without accelerators, readily initiate curing of the ethylenically unsaturated compound at room temperature.
In these cases the use of RF technique to supply rapid heat to the composition it merely to melt or decompose the wall of the encapsulating material so as to allow the initiator to make contact with the ethylenically unsaturated compound and initiate curing. Similarly, certain Lewis acids, e. g., BF3, readily initiate curing of epoxies on contact at room temperature, and thus the use of RF serves the same purpose as just stated.
The polymerization initiators used herein for curing the ethylenically unsaturated containing group member of the composition are free radical initiators selected from substituted or unsubstituted pinnacles, ago compounds, thrums, organic peroxides and mixtures thereof.
Additionally, iodonium salts, discussed hereinafter, can be used per so, or in combination with pinnacles for the faster curing, to initiate the polymerization of ethylenically unsaturated compounds.
The organic peroxides operable are of the general formula:
( 1 on wherein n = O or 1, R is independently selected from hydrogen, aureole, alkyd, aureole carbonyl, alkaryl carbonyl, aralkyl carbonyl and alkyd carbonyl and Al is alkyd or aureole, said alkyd groups containing 1 to 20 carbon atoms.
Examples of operable organic peroxides include, but are not limited to 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, 153-bis(t-butylperoxyisopropyl)benzene, Boyce-(cumylperoxyisopropyl)benzene, 2,4-dichlorobenzoyl peroxide, caprylyl peroxide, laurel peroxide, t-butyl peroxyisobutyrate, bouncily peroxide, p-chlorobenzoyl 7~7~
peroxide, hydroxyheptyl peroxide, di~t-butyl diperphthalate, t-butyl per acetate, t-butyl perbenzoate, dicumyl peroxide, l,l-di(t-butylperoxy) 3,3,5-trimethyl-cyclohexane, di-t-butyl peroxide and t-butyl hydroperoxide.
The organic peroxide is added to the composition in an amount ranging from 0.01 - 10%, preferably 0.1 - I by weight based on the weight of the ethylenically unsaturated group member.
Examples of ago compounds operable herein include, but are not limited to, commercially available compounds such as 2-t-butylazo-2-cyanopropane; 2,2'-azobis-(2,4-dimethyl-

4-methoxy-valeronitrile3 2,2'-azobis-(isobutyronitrile);
2,2'-azobis(2,4-dimethylvaleronitrile) and l,l'-azobis-(cyclohexanecarbonitrile).
The ago compound is added to the composition in an amount ranging from 0.001 - 5%, preferably 0.01 - I by weight based on the weight of the ethylenically unsaturated group member.
The thrums operable as thermal initiators herein are of the formula:
Al S R3 wherein Al, R2, R3 end I taken singly can be hydrogen, linear or branched alkyd having from 1 to about 12 carbon atoms, linear or branched alkenyl having from 2 to about 12 carbon atoms, cycloalkyl having from 3 to about lo ring carbon atoms, cycloalkenyl having from 3 to about lo ring carbon atoms, aureole having from 6 to about 12 ring carbon atoms, arkaryl having from 6 to about 12 ring carbon atoms, aralkyl having from 6 to about 12 ring carbon atoms and when taken together, Al and R2 and R3 and R4 can each be a diva lent alkaline group (-CnH2n-) having from 2 to about 12 carbon .. . .

~23~7~
atoms, a diva lent alkenylene group (-CnH2n_2-) having from 3 to about lo carbon atoms, a diva lent alkadienylene group (-CnH2n 4-) having from 5 to about lo carbon atoms, a diva lent alkatrienyl.ene group (-CnH2n 6-) having from 6 to about lo carbon atoms, a diva lent alkylene-oxyalkylene group (-CXH2XOcx~l2x having a total of from 4 to about 12 carbon atoms or a diva lent alkyleneaminoalkylene group:
( -CxH2xNcxH2x~ ) having a total of from 4 to about 12 carbon atoms Operable thrums include, but are not limited to, tetramethylthiuram disulfide, tetraethylthiuram disulfide, di-N-pentamethyleneth.iuram disulfide, tetrabutylthiuram disulfide, diphenyldimethylthiuram disulfide, diphenyl-diethylthiuram disulfide and diethyleneoxythiuram disulfide and the' like.
The thrum is added to the composition in an amount ranging from 0.005 5~0% by weight of the ethylenically unsaturated group member.
The substituted or unsubstituted pinnacles operable herein as a thermal initiator have the general formula:

X Y
wherein Al and R3 are the same or different substituted or unsubstituted aromatic radicals, R2 and R4 are substituted or unsubstituted aliphatic or aromatic radicals and X and Y which may be the same or different are hydroxyl, alkoxy or airlocks.
Preferred pinnacles are those wherein Al R2, R3 and R4 are aromatic radicals, especially phenol radical and X and Y are hydroxyl.

~37~7~
Examples of this class of compounds include, but are not limited to, benzopinacol, 4,4'-dichlorobenzopinacol, ~,4'-dibromobenzopinacol, 4,4'-diiodobenzopinacol, ~,4',4",4"'-tetrachlorobenzopinacol, 2,~-2',4'-tetrachloro-benzopinacol, ~,4'-dimethylbenzopinacol, 3,3'-dimethyl-benzopinacol, ~,2'-dimethylbenzopinacol, twitter-methylbenzopinaco], 4,4'-dimethoxybenzopinacol, 4,4', 4",4"'-tetramethoxybenzopinacol, ~,4'-diphenyl-benzopinacol, 4,4'-dichloro-4 n on -dimethylbenzopinacol, 4,4'-dime~hyl-4",4"'-diphenylbenzopinacol, xanthonpinacol, fluorenonepinacol, acetophenonepinacol, 4,4'-dimethylaceto-phenonepinacol, 4,4'-dichloroacetophenonepinacol, 1,1,2-triphenyl-propane-1,2-diol, 1,2,3,4-tetraphenyl-butane-2,3-diol, 1,2-diphenylcyclobutane-1,2-diol, propiophenone-pinacol, 4,4'-dimethylpropiophenone-pinnacle, 2,2'-ethyl-3,3'-dimethoxypropiophenone-pinacol, 1,1,1,4,4,4-hexafluoro-2,3-diphenyl-butane-2,3-dioof.
As further compounds according to the present invention, there may be mentioned: benzopinacol-mono-methyl ether, benzopinacol-mono-phenylether, benzopinacol and monoisopropyl ether, benzopinacol monoisobutyl ether, benzopinacol moo (diethoxy methyl) ether and the like.
The pinnacle is added to the composition in amounts ranging from ~.01 - 10~, preferably 0.1 - I by weight based on the weight of the ethylenically unsaturated group member.
The polymerization initiators employed when the group member is an epoxy containing at least two I

groups are ionic polymerization initiators selected from dicyandiamide, BF3 adduces, Lewis acids, diaryliodonium salts and diaryliodonium salts admixed with pinnacles.
The BF3 adduces used herein as polymerization initiators include, but are not limited to, ~3~7~
C6H5NH2'BF3~ EQUINE 3, E~NH2~BF3, seC-BU2NH^BF3, Et2NH.BF3, (C6H5)3P BF3~ C6H5NMe2 3 Pyridine~BF3, and Et3N~BF3, Et20~BF3, (HOCH2CH2)3N~BF3. Also, Lewis acids such as BF3~ Snuck, SbC15, SbF5, PF5, HBF4, HPF6 and HSbF6 are operable.

The diaryliodonium salts operable herein as polymerization initiators are those set out in U. S. 4,238 9 587.

That is, the diaryliodonium salts which can be utilized in the practice of the invention are shown as follows:
I [wrier byway] [Y] , (1) where R is a C~6 13) aromatic hydrocarbon radical, Al is a diva lent aromatic organic radical, and Y is an anion, a is equal to O or 2, b is equal to O or 1 and the sum of a b is equal to 1 or 2. Preferably, Y is an Mud anion where M is a metal or metalloid, Q is a halogen radical and d is an integer equal to foe.
Radicals included within R of formula (1) can be the same or different aromatic carbocyclic radicals having from 6 to 20 carbon atoms, which can be substituted with from 1 to 4 monovalent radicals selected from (1-8)alkXY~ C(1-8) alkyd, vitro, sheller, etc. R is more particularly phenol, chlorophenyl, nitrophenyl, methoxyphenyl, pyridyl, etch Radicals included by Al of formula (1) are diva lent radicals such as , . Jo ~;23~

where Z is selected from -O-, -S-, O O O R
.. .. .. .
Sheehan CON

R is Colloquial or Charlie, and n is an integer equal to 1-8 inclusive.
Metals or metalloids included by M of formula (1) are transition metals such as 5b, Fez Sun, Bit Al, Gay In, Tip or, So, V, Or, My, Us, rare earth elements such as the lanthanides, for example, Cud, Pry No, etc., astounds, such as Thy Pa, U, No, etc., and metalloids such as B, P, As, Sub, etc. Complex anions included by Ed are, for example, BY , PF6-, AsF6 , SbF6-, Fake , SnClG~, SbC16~, Buick- , etc.
Some of the diaryliodonium salts which can be used in the practice of toe invention are as follows:
HO

[I

Noah $_ I aft-, I

.
., J

37~3 These polymerization initiators are Audi to the system in an amount ranging from 1 to 10% by weight of the epoxy resin Thus, wren an ethylenically unsaturated group member and an epoxy resin are added in combination to form a thermoses adhesive, it is necessary to-add both the aforementioned free radical type and an ionic type in the amounts specified in order to obtain a cocured adhesive The BF3 adduces and iodonium salts are operable per so to initiate both cross linking reactions but preferably are used in combination with the free radical initiators disclosed heretofore due to the faster cure Wright The polymerization initiator is added to the system as an encapsulant. Numerous techniques, both chemical and mechanical, are available for micro encapsulating substances, such as the polymerization initiators herein.
See, for example, U. S. Patent Nos. 2,665,228, 2,800,457, 2,80U,458 (U. S. Patent Rev 24,899), 2,846,971, 2,969,330, 2,g6g,331, 3,015,128, 3,041,289, 3,056,728, 3,091,567, 3,121,698, 3,159,585, 3,172,878, 3,317,433, 3,839,2~0, 4,237,252; British Patent No. 1,091,141 and Micro-encapsulation, a special report published by Management Reports, Boston (1~63).
Virtually, any kind of compound can be encapsulated in any of a number of encapsulating media, by one or more encapsulating processes. These processes include the simple and complex coacervation processes, the interracial polymerization process, the organic phase separation method, the exchange process and the meltable dispersion process, all of which are described in the references noted above.
For encapsulating the thermal initiators employed herein, the mechanical process set out in U. S. 3,015,128 can be used ~23~
Therein a multiple-orifice, centrifugal apparatus which forms a continuous film of the encapsulating wall material across the orifice of a nozzle upon which the polymerization initiator impinges is used.
The rotational force causes the film to distend and finally break loose with the polymerization initiator -enveloped.
As the encapsulating material used herein, it is possible to employ any thermoplastic material having a melting point higher than 50~C Preferred thermoplastic materials include, but are not limited to, polyethylene, ethylene vinyl acetate, polyvinyl alcohol, polymethyl methacrylate, epoxies, urethanes and urea formaldehyde The micro capsules herein employed have an average diameter in the range 100 1,500 microns, preferably 500 -1,000 microns.
In practicing the instant invention it is possible to have one or more thermal initiators in the same capsule or have separate capsules for each initiator. For example, when one is polymerizing a mixture of the ethylenically unsaturated monomer and an epoxy resin, it is possible to homogeneously admix micro capsules containing a peroxide thermal initiator for the ethylenically unsaturated monomer and a BF3 adduce thermal initiator for the epoxy resin. Furthermore, when inductive heating is employed and a particulate electromagnetic energy absorbing material, e. 9., iron, is added to the system, this material can also be encapsulated per so or in combination with one of the thermal initiators ware must be exercised that no reaction occurs between the particulate electromagnetic energy absorbing material and the thermal initiator. If such a reaction is possible, then these materials are encapsulated separately. Additionally, the particulate electromagnetic energy absorbing material can .

I
also be adder to the ethylenically unsaturated compound, epoxy resin or mixture thereof without being encapsulated.
The thermoplastic adhesive material component of the heat activatable adhesive organic resin composition which is optionally added can be made up of various saturated and unsaturate thermoplastic polymers and copolymers, the term "copolymers" including ~erpolymers, tetrapolymers, etc.
These thermoplastic adhesive materials along with the remainder of the organic resin composition can be applied in hot melt form as a one part adhesive. These thermoplastic adhesive materials are composed of 100 non-volatile materials, i. e., containing no water, solvent or other volatile carriers. They are solid or liquid at room temperature but become more fluid at elevated temperatures, thereby allowing for easy application. The thermoplastic adhesive materials operable herein include, but are not limited to, polyamides, polyvinyl chloride, polyvinyl acetals and polyester resins, ethylene-vinyl acetate (EVA) copolymers, ethylene-ethyl acrylate tea) copolymers, butadiene-acrylonitrile copolymers and styrene~ethylene-butylene copolymers. Some of the newer materials of the more conventional "rubber" variety are the block copolymers, styrene-butadiene or styrene-isoprene sold under the trade name "Keaton".
One thermoplastic adhesive material useful in the adhesive compositions of the present invention includes those thermoplastic segmented copolyesters disclosed in U. S. Patent No. 4~059,715, These are solid, non-tacky, strongly cohesive;
solvent-free thermoplastic polymers which are themselves not subject to cold flow and are non locking below their melting temperatures but which become aggressively tacky aye and bondable upon being melted. They consist essentially of from about 5 to 75 percent by weight of amorphous ester units and 95 to 25 percent by weight of crystallizable ester units joined through the ester linkages.
Other thermoplastic adhesive materials which are useful in the adhesive compositions of the present invention include other thermoplastic polyester (en g., that available under the trade designation ~5096"
from Cooper Polymers, Ionic thermoplastic polyurethane (e. g., that available under the trade designation ~Q-thane PI 56'' from K. J. Quinn Co., Inc.), thermoplastic polyamides (e. g., that available under the trade designation "Caromed 2430" from Cooper Polymers, Inc.), "Elvamides" available from Dupont and "Macro melt"
available from Henkel; thermoplastic rubbers (e. g., those available under the trade designation "Keaton 1101" and "Keaton 1107" from Shell Chemical Co.) and ethylene vinyl acetate (e. go, that available under the trade designation "Elvax 40" from E. I. Dupont de Numerous Co., Inc. and "Ultrathin" available from US). Still other thermoplastic adhesive materials operable as a component in the adhesive organic resin composition include, but are not limited to, butydiene-acrylonitrile copolymers available under the trade designation "Hiker" from B. F. Goodrich, urethane-acrylates, urethane-epoxides and urethane-polyenes. In addition, other thermoplastic materials are polyvinyl acetals such as polyvinyl formal and polyvinyl betrayals. The thermoplastic adhesive material, when present, is present in the composition in amounts ranging from 1~9S% by weight with the balance being the ethylenically unsaturated and/or epoxy resin.
In the instances where the optional thermoplastic adhesive material contains ethylenic unsaturation, e. g., styrene-butadiene copolymers and ethylene propylene * Trademark I" ' .

37~3 Dunn monomer, it is possible or cocuring with the ethylenically unsaturated group member to occur on heating. When the thermoplastic adhesive material is void of such groups, in most cases it merely acts as a matrix for the crosslinkable ethylenically unsaturated or epoxy group member thereby providing additional adhesive properties.
The compositions of the present invention may, if desired, include such conventional additives as antioxidant, inhibitors, fillers, antistatic agents, flame-retardant agents, thickeners, thixotropic agents, surface-active agents, viscosity modifiers, plasticizers, tackifiers and the like within the scope of this invention. Such additives are usually preblended with the lo ethylenically unsaturated or epoxy compound prior to or during the compounding step. operable fillers which can be added to the system to reduce cost include natural and synthetic resins, glass fibers, wood flour, clay, silica, alumina, carbonates, oxides, hydroxides, silicates, glass flakes, borate, phosphates, diatomaceous earth, talc, kaolin, barium sulfate, calcium sulfate, calcium carbonate, wollastonite, carbon fibers and the like. The aforesaid additives may be present in quantities up to 500 parts or more per 100 parts of the organic resin composition by weight and preferably about OWE to about 300 parts on the same basis.
Additionally, scavengers and antioxidant such as hydroquinone, pyragallol, phosphorous acid, tert-butyl hydroquinone, tert-butyl catcall, p-benzoquinone, 2~5-diphenylbenzo-quinone, 2,6-di-tert-butyl-p-cresol, etc., are added to the system in conventional amounts ranging from 0.001 to 2.0% by weight of the ethylenically unsaturated or epoxy group member.
the polymerization reaction is usually carried out by 5 rapidly heating the composition by RF techniques to a 3~7~

temperature above the melting point of the encapsulating wall material and above the disassociation temperature of the polymerization initiator, i. e., in the range 70-300C, preferably 90-170C. Once contact between the polymerizable group member and the disassociated polymerization initiator occurs, periods ranging from 1 second to 2 minutes are sufficient to fully cure the composition to a solid, thermoses adhesive or sealant product.
The heating step using an encapsulated polymerization initiator to cure the adhesive organic resin composition is accomplished by radio frequency (RF) techniques. RF
heating can be utilized as a faster and more efficient means of curing than conventional air oven heating, especially where the substrates to be bonded are plastic materials. In addition to the formation of high strength bonds, RF bonding techniques aid in (a) fast bond setting times, and (b) automated part handling and assembly.
In practicing the instant invention, RF heating can be employed with the adhesive composition herein to adhere (1) plastic to plastic, (2) plastic to metal and (3) metal to metal. For example, dielectric heating can be used to bond I and (2) swooper if one member ox the adhesive composition, i. e., resin, encapsulant shell wall or polymerization initiator, contains sufficient polar groups to heat the composition rapidly and allow it to bond the adherents Inductive heating can also be used to bond if), (2) and (3). That is, when at least one of the adherents is an electrically conductive or ferromagnetic metal, the heat generated therein is conveyed by conductance to the adhesive composition thereby initiating the cure to form a thermoses adhesive. In the instance where both adherents are plastic, it is necessary to add an energy absorbing material, i. en, an electrically ~37~

conductive or ferromagnetic material, preferably in fiber or particle form (10-400 mesh), either per so or encapsulated to the adhesive composition. The energy absorbing material is usually added in amounts ranging from 0.1 to 2 parts by weight, per l part by weight of the Audi organic resin composition.
The particulate RF energy absorbing material used in the adhesive composition when induction heating is employed can be one of the magnetizable metals including iron, cobalt and nickel or magnetizable alloys or oxides of nickel and iron and nickel and chromium and iron oxide. These metals and alloys have high Curie points (730-2,040F).
Electrically conductive materials operable herein when inductive heating is employed include, but are not limited to, the noble metals, copper, aluminum, nickel, zinc as well as carbon black, graphite and inorganic oxides.
There are two forms of radio frequency heating operable herein, the choice of which is determined by the material to be adhered. The major distinction is whether or not the material is a conductor or non-conductor of electrical current. If the material is a conductor, such as iron or steel, then the inductive method is used. If the material is an insulator, such as wood, paper, textiles, synthetic resins, rubber, etc., then dielectric heating can also be employed.
Most naturally occurring and synthetic polymers are non-conductors and, therefore, are suitable for dielectric heating. These polymers may contain a variety of dipoles and ions which orient in an electric field and rotate Jo maintain their alignment with the field when the field oscillates. The polar groups may be incorporated into the polymer backbone or can be pendant side groups, additives, extenders, pigments, etc. For example, as additives, it lousy fillers such as carbon black at a one percent level can be used to increase the dielectric response of the adhesive. When the polarity of the electric field is reversed millions of times per second, the resulting high frequency of the polar units generates heat within the material The uniqueness of dielectric heating is in its uniformity, rapidity, specificity and efficiency. Most plastic heating processes such as conductive, convective or infrared heating are surface-heating processes which in order to establish a temperature within the plastic must subsequently transfer the heat to the bulk of the plastic by conduction. Hence, heating of plastics by these methods is a relatively slow process with a non-uniform temperature resulting in overheating of the surfaces. By contrast, dielectric heating generates the heat within the material and is therefore uniform and rapid, eliminating the need for conductive heat transfer. In the dielectric heating system herein the electrical frequency of the electromagnetic field it in the range 1-3,000 megahertz, said field being generated from a power source of 0.5-1,000 kilowatts.
Induction heating is similar, but not identical, to dielectric heating. The following differences exist:
(a) magnetic properties are substituted for dielectric properties; (b) a coil is employed to couple the load rather than electrodes or plates; and (c) induction heaters couple maximum current to the load. The generation of heat by induction operates through the rising and falling of a magnetic field around a conductor with each reversal of an alternating current source. The practical deployment of such field is generally accomplished by proper placement of a conductive coil.
When another electrically conductive material is exposed I
to the field, induced current can be created. These induced currents can be in the form of random or "eddy"
current which result in the generation of heat.
Materials which are both magnetizable and conductive generate heat more readily than materials which are only conducive the heat generated as a result of the magnetic component is the result of hysteresis or work done in rotating magnetizable molecules and as a result of eddy current flow. Polyolefins and other plastics are neither magnetic nor conductive in their natural states.
Therefore, they do not, in themselves, create heat as a result of induction.
The use of the RF induction heating method for adhesive bonding of plastic structures has proved feasible by interposing selected RF energy absorbing materials in an independent adhesive composition layer or gasket conforming to the surfaces to be bonded, RF energy passing through the adjacent plastic structures (free of such energy absorbing materials) is readily concentrated and absorbed in the adhesive composition by such energy absorbing materials thereby rapidly initiating cure of the adhesive composition to a thermoses adhesive.
RF energy absorbing materials of various types have been used in the RF induction heating technique for some time. For instance, inorganic oxides and powdered metals have been incorporated in bond layers and subjected to RF
radiation. In each instance, the type of energy source influences the selection of energy absorbing material.
Where the energy absorbing material is comprised of finely divided particles having ferromagnetic properties and such particles are effectively insulated from each other by particle containing nonconducting matrix material, the heating effect is substantially confined to that resulting from the effects of hysteresis. Consequently, heating is - I -Allah limited to the "Curie" temperature of the ferromagnetic material or the temperature at which the magnetic properties of such material cease to exist The RF adhesive composition of this invention may take S the form of an extruded ribbon or tape, a molded gasket or cast sheet or film. In liquid form it may be applied by brush to surfaces to be bonded or may be sprayed on, pumped or used as a dip coating for such surfaces.
The foregoing adhesive composition, when properly utilized as described hereinafter results in a solvent free bonding system which permits the joining of metal or plastic items without costly surface pretreatment. The RF
induced bonding reaction occurs rapidly and is adaptable to automated fabrication techniques and equipment.
To accomplish the establishment of a concentrated and specifically located heat zone by induction heating in the context of bonding in accordance with the invention, it has been found that the RF adhesive compositions described above can be activated and a bond created by an induction heating system operating with an electrical frequency of the RF field of from about 0.1 to about 30 megacycles and preferably from about 0.3 to 30 megacycles, said field being generated from a power source of from about 1 to about 30 kilowatts, and preferably from about 2 to about

5 kilowatts. The RF field is applied to the articles to be bonded for a period of time of less than about 2 minutes.
As heretofore mentioned, the RF induction bonding system and improved RF adhesive compositions of the present invention are applicable to the bonding of metals, thermoplastic and thermoses material, including fiber reinforced ~hermoset material.
The following examples are set out to explain, but expressly not limit, the instant invention. Unless otherwise noted, all parts and percentages are by weight.

I
Strength properties of adhesive in shear by tension loading were run in accord with ASTMD 1002-64 based on one inch square of lapped area.
Impact measurements were made in accord with STYMIE D
1822-61T except sample is lapped 1" x 1/2" and impart is on the side of the lap.
Example 1 ~F3 gas was dissolved into 52 3 g of ethylene glycol until 47.7 9 of weight Cain was obtained. The reaction was carried out at 10 - 15C by cooling the reactor with an ice-water mixture The BF3 complex was diluted with 138.5 9 of propylene glycol and, thereafter, micro encapsulated in polyethylene by conventional means.
The micro capsules containing 52~ of the BF3 complex having an average diameter of no - Lowe microns will be used hereinafter a a thermal initiator.
Example 2 A master batch comprising 100 parts of an epoxy resin, commercially available from Shell Chemical Co. under the trade name "Epon-828", 100 parts of iron powder having an average diameter in the range 100 - 200 microns and 20 parts of the encapsulated BF3 thermal initiator from Example 1 were homogeneously admixed. A portion of the admixture was spread between fiber reinforced polyester US adherents. 6 samples were mad up. The adherents with the admixture there between were clamped together and cured in a 2 ow EMABond generator, Model EYE, at a frequency of 8 MHz at 110~ load and 0.2 amp for various time periods. The samples were then measured for lap shear strength. The results are shown in TABLE I:
* Trademark ~23~37~

TABLE I

Eon 828 Iron Capsule Lap Powder Shear ho (phi) 100 100 20 40 5 sec. at 84% of maximum output 100 100 20 70 10 sec. at 84~ of maximum output 100 100 20 160 30 sec. at 84% of maximum output 100 100 20 230 40 sect at 84% of maximum output 100 100 20 310 50 sec. at 84~ of maximum I output 100 100 20 320 60 sec. at 84% of maximum output a) RF energy supplier - EMABond EYE:
Frequency 8 MHz Output Power 2 ow Load Meter 110~
Grid Meter 0.2 ampler Example 3 Control runs using conventional heating means, e. g., a forced air oven and pressure for curing were made up as in Example 2. The results are shown in TABLE II:

Allah TABLE II
Eon 828 Iron Capsule Lap Powder Shear (phi) (EEL Curing Conditions -100 100 20 90 160C, 20 minutes 100 - 20 80 160C, 20 minutes 100 100 20 120 Pressure Room T, 20 mix .
100 - 20 70 Pressure, Room T, 20 min.
b) Pressure - 2,000 psi. in a platen press As can readily be seen, the use of inductive heating not I only increases the cure speed but also results in a higher lap shear strength.
Example 4 At room temperature, 80 9 of bouncily peroxide was dissolved in 90 9 of t-butyl perbenzoate to form a homogeneous clear solution. This solution was then micro encapsulated in polyethylene by conventional means.
The micro capsule containing 10% of peroxide solution and having an average diameter of 425 to 707 microns will be used as a thermal initiator.

A master batch comprising 100 parts of a dimeth-acrylate, commercially available from Shell Chemical co.
under the trade name "Epocryl 12", 100 parts of iron powder having an average diameter of 150 microns, 16.7 parts of micro encapsulated initiator from Example 4 and 3.3 parts of micro encapsulated N,N-dimethylaniline as curing accelerator having a payload of 74.5% were homogeneously admixed. This mixture was applied to fiber reinforced polyester adherents and cured for various time * Trademark 7~7~

periods by the procedure and conditions described in Example 2. The results are shown in TABLE III:

TABLE I I I

Capsule Epocryl 12 Iron Lap Curing Powder Shear Time ( pi r ) AL
~00 100 16.7 3.3 4 5 100 100 16.7 3.3 75 10 100 100 16~7 3.3 372 20 100 100 16.7 3.3 469 30 100 100 16.7 3.3 478 40 100 100 16.7 3.3 551 .50 100 100 1~.7 3.3 553 60 A mixture containing 10 g of the master batch from Example 2 and 10 g of the master batch from Example 5 was applied to fiber reinforced polyester adherents and cured for various time periods by the procedures described in Example 2. The results are shown in TABLE IV:

TABLE IV

Example 2 Example slap Shear Cure Time Resin Resin (psi) ( c) .

~L;237~7~
Example 7 Without the addition of iron powder, the samples having the same compositions as Examples 2, 5 and 6 were cured within 5 minutes in a radio frequency dielectric heating equipment. All had commercially acceptable lap shears.
Example 8 120 g of an epoxy resin, commercially available from Shell Chemical Co. under the name PUN, were admixed with 80 g of an acrylonitrile-butadiene copolymer with carboxylate end groups, commercially available from B. F. Goodrich under the trade name HIKER, and 0.5 g of triphenylphosphine. The admixture was reacted at 110 -120~C for 3 hours to form an epoxy terminated prepolymer, hereinafter referred to as Prepolymer A.
Example 15 parts of Prepolymer A from Example 8 were admixed with 85 parts of EPON-828, 6 parts of dicyandiamide, 5 parts of triphenylphosphine and 4 parts of BF3 complexes with ethylene glycol and propylene glycol encapsulated in polyethylene The admixture was applied between carbon steel shims at a thickness of 2 miss, and the shins were lapped. 10 samples were thus prepared.
The samples were placed in an induction heating apparatus and at a frequency of 350 kilocycles were heated for 4 seconds at 170~C. After removal from the induction heating apparatus 5 samples had an average impact strength of 9 inch pounds and an average lap shear strength of 1147 psi. The remaining 5 samples were subjected to a further cure in an air oven for 17 minutes at 170C. The average impact strength of these samples was 16 inch pounds, and the average lap shear strength was 2,673 psi.

* Trademark I

N N,dimethylaniline (74.4~ pay load) was encapsulated in polyethylene having an average diameter in the range of 250-425 microns, hereinafter referred to as encapsulant A.
10 parts of bouncily peroxide and 90 parts of t-butyl perbenzoate (66.70% pay load) were separately encapsulated in polyethylene capsules having an average diameter in the range 425-707 microns, hereinafter referred to as encapsulant B.
One part of encapsulant was thoroughly admixed with 2 parts of encapsulant B.
5 parts of the above encapsulant admixture were added to a commercially available polyester prepared from 25 mole percent malefic android, 25 mole percent phthalic acid and 50 mole percent polypropylene glycol which was subsequently admixed with 42~ styrenes monomer After thorough mixing, the admixture was applied at a thickness of 2 miss in a 1~2" overlap between 2 carbon steel adherents. The adherents were placed in an induction heating apparatus and at a frequency of 350 kilocycles were heated for 4 seconds at 170C. A
solid bond resulted.
Example 11 7.5 parts of polyvinyl bitterly having a weight average molecular weight in the range 45,000-55,000, commercially available from Monsanto under the trade name "Butvar B-76", and 2.5 g of diglycidyl ether of bisphenol A having a viscosity of 11,000-14,000 cups at 25C and an epoxy equivalent weight of 182-18g, commercially available from Dow Chemical Co. under the trade name NUDER 331", won admixed in 60 ml of ethylene chloride. After a homogeneous mixture was formed, the ethylene chloride was evaporated. 5 parts of BF3 complexes with ethylene glycol and propylene glycol encapsulated in polyethylene * Trademark ~37~7~

range 500-707 microns were added to 100 parts of the above epoxy-polyvinyl bitterly admixture. The admixture was applied between carbon steel adherents in a 1/2" overlap at a thickness of 2 miss. The adherents were placed in an induction heating apparatus and at a frequency of 350 kilocycles were heated for 4 seconds at 284C. An average of 4 samples had a mean lap shear strength of 866 psi.

Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for adhering two substrates which comprises contacting said substrates with a heat curable organic resin composition comprising:
(1) a member of the group consisting of (a) an ethylenically unsaturated compound, containing at least 2 carbon-to-carbon double bonds;
(b) an epoxy resin containing at least 2 groups in combination with (a);
(2) an encapsulated polymerization initiator for (1);
and (3) a thermoplastic adhesive material selected from the group consisting of polyesters, polyvinyl acetals, polyvinyl chloride, polyamides, butadiene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-ethylene-butylene copolymers, ethylene-vinyl acetate copolymers, ethylene propylene diene monomer, acrylic and methacrylic acid and their esters and mixtures thereof, and applying heat thereto by radio frequency (RF) means.

2. The process according to Claim 1 wherein the radio frequency means are by dielectric heating.

3. The process according to Claim 1 whereby the radio frequency means are by induction heating, and ferromagnetic and/or electrically conductive particles are added to the composition.

4. The process according to Claim 3 wherein the particles are in encapsulated form.

5. The process according to Claim 4 wherein the capsules containing the particles also contain the polymeriza-tion initiator.

6. The process according to Claim 1 wherein the group member is an epoxy resin containing at least 2 and groups and the polymerization initiator is a BF3 adduct.

7. The process according to Claim 1 wherein the group member is an ethylenically unsaturated compound containing at least 2 carbon-to-carbon double bonds.

8. The process according to Claim 1 wherein the group member is a mixture of an ethylenically unsaturated compound containing at least 2 carbon-to-carbon double bonds and an epoxy resin containing at least groups.

9. The process according to Claim 1 wherein the substrates to be adhered are both metal.

10. The process according to Claim 1 wherein the substrates to be adhered are both plastic.

11. A process for adhering two substrates which com-prises contacting said substrates with a heat curable organic resin composition comprising:
(1) a member of the group consisting of (a) an ethylenically unsaturated compound, containing at least 2 carbon-to-carbon double bonds, and (b) an epoxy resin containing at least groups in combination with (a);
(2) a polymerization initiator for (1); and (3) encapsulated ferromagnetic and/or electrically conductive particles.

12. The process of Claim 11 wherein the resin composi-tion further comprises:
a thermoplastic adhesive material selected from the group consisting of polyesters, polyvinyl acetals, polyvinyl chloride, polyamides, butadiene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-ethylene-butylene copolymers, ethylene-vinyl acetate copolymers, ethylene propylene dine monomer and mixtures thereof, and applying heat thereto by radio frequency (RF) inductive means.