CA1048198A - Epoxide blend for polymerizable compositions and polymerizing process - Google Patents

Abstract

ABSTRACT

A blend of epoxide materials is provided which, although essentially free of volatile solvents, is liquid and tractable for coating and related applications at or near room temperature. The epoxide materials include an epoxy prepolymer of the type of glycidyl-bisphenol A resins, epoxidized novolaks, polyglycidyl ethers, and alicyclic diepoxides,blended with a bis(epoxycycloalkyl ester and in many cases also with a low viscosity monoepoxide in limited proportions. The compositions preferably include additionally a cationic polymerization initiator, preferably a radiation-sensitive catalyst precursor, and epoxide polymer are produced by coating such compositions on a substrate, followed by application of energy, through heating or preferably through irradiation, to effect substantial polymerization of the epoxidic materials of the coating.

Description

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1~8~98 :' BACKGROUND OF TNE INVENTION

Coating, printing, and related processes conventional are carried out by dissolving film-forming ingredients in a ~ol~t~leesolvent~ applying the resulting composition to a sub- . ~
strate, and drying and curing the transferred material with or without heating, whereby the volatile solvent is released to the atmosphere. Evolution of the solvent tends to lengthen the hardening process and to leave voids and pinholes in the cured coatings, making them porous. Emission of volatile solvents tends to pollute the adjacent air unless costly arrangements are made to recover practically all of the solvent, and release . of flammable volatile solvents may create fire and explosion hazards~ Heat ing often is required to hasten removal of the solvent, but the higher temperatures produced may damage the :, : ... . . ..

~48198 1 substrate, or !na~ cause running and deformation Or the coat-ing while it stlll is soft.
Solvent-free mixtures of epoxide materials may be prepared based essentially, for example, on certain epoxidlc - - prepolymers such as the reaction products of epichlorohydrln - with bisphenol A or with novolaks. Such prepolymers have been blended with various monoglycidyl ethers, or with a glycol diglycidyl ether, primarily to modify the viscosity of the prepoly~er Such mlxtures can be shaped, as by coating, and then treated with an activated cationic initiator to cure the resin. However, these prepolymeric mixtures do not provide the rheological properties most desirable for certain coating or related operations, or are unsuited for applicatlon to various type~ o~ substrates. Coating and printing machines require - unique combinations of pr~perties to permit smooth and rapid flow Or the coa~ing and printing compositions through the ~ machines for proper application to the substrate web or sheets - supplied to the machines~ It al50 has been observed that modirication of the solvent-free epoxide rnaterials with so-- 20 called reactive diluents, such as morloglycidyl ethers~ to ob-tain the desired rheological properties tends to decrease the speed of curing and to diminish the hardness of the ma~erial after initiation o~ polymerization and curing, giving a more or less soft or t~cky finish rather ~han a tough~ solld r f~nish. Efforts to avoid this problem by the tnclusion of hardeners, such as amines, amides, or anhydrides, lead to premature curing immediately upon mixin6 and a tendency to ; bri~tleness in the cured material. It is an ob~ect o~ the present inventlon to provide epoxid@ blends suitable for use .

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in polymerizable compositions, ancl to provide a related poly-merizing process, which substantially avoid these difficulties and disadvantages encountered with prior materials and processes.
~ SUMMARY or~ TE~E INVE~TIO
j -I Accordingly, a new and improved blend of epoxide -il materials, fluid at room temperature, consists essentially of at least one epoxidic prepolymer material having an epoxy equiv-alent weight below 200, constituting between about 10~ and 85% of the weight of the blend, and selected from the group consisting of an epoxy resin prepolymer consisting predominant-ly of the monomeric diglycidyl ether of bisphenol A, a polyepox-idized phenol or cresol novolak, a polyglycidyl ether of a poly-- hydric alcohol, and a diepoxide of a cycloalkyl or alkylcyclo-.;
, alkyl hydrocarbon or ether; the blend consist additionally of ~ at least 15% by weight of an epoxidic ester haviny two epoxy-.,. "
cycloalkyl groups, and from 0-15% by weight of a monoepoxide having a viscosity at 23C of less than 20 centipoises. Polymeri-. zable compositions advantageously consist essentially of the above-specified ingredients and a radiation-sensitive catalyst -precursor which decomposes upon application of eneryy to provide ~j a Lewis acid catalyst effective to initiate polymerization of the above-mentioned epoxidic materials. Such compositions are especially useful in providing rapidly curable coatinys, which may contain no more than a few percent by weight of unpolymeriz-able materials. Thus, in accordance with the process of the .' .~ lnventlon, an epoxidized polymer is produced by forming a mixture of the epoxidic materials mentioned above and the catalyst precur-sor, applying the mixture so formed to a substrate, and subsequen-tly applying energy to the mixture on the substrate to - :, ' , 81g~

release the Lewis acid catalyst in sufficient amounts to effect substantial polymerization of the epoxidic ll~terials.

DETAIL~D DESCRIPTION
There ls provided and utilized, in accordance with the present lnvention, a blend vf epoxide materlals which is fluid at room temperature. This blend includes a materia~ designated for convenience as a prepolymeric ~ater-ial, which is described ln detail hereinbelo~l. The blend ~lso includes an ester having two epoxycycloalkyl groups, designated for convenience as a bis(epoxycycloalkyl) ester.
The blend may include further, in limited quantities, a mono-epoxi~e ~aterial of specified maximum viscosity. To provide a po~y!nerizable composition, a cationlc initiator is ~nixed or dissolved in the blend.
Prepolyl~eric materlal. The blend of epoxide materials, fluid t roon temperature, contains at least one prepolymeric mat-erial having an epoxy equivalent weight below 200 and selected ,, ~:?`'~ from the group consisting of (A) an epoxy resin prepoly~er of the glycidyl-bisphenol A polyether t~rpe, ~B) a polyepoxidized - ~ . phenol or cresol novola'~, (C) a polyglycidyl eth~r of a poly-~ ~ hydric alcohol~ and ~D) a diepoxide of a cycloalkyl or al~yl-;~ ~ cycloalkyl hy~rocarbon or ether. This epoxidic prepolymer .
;c~ material constitutes be~Jeen 10~ and 85~ of ~he weight of the ;, :
v~ blend.
- ~ Referrin6 first to the resin prepolymer of the glycidyl-bisphenol A polyester type, (A), the classic epoxy resin Ls obtained by the well knoWn reaction vf epichlorohydrin .
~ (l-chloro-2,3-epoxypropane) and bisphenol A (4,~'-isopropylidene-; ~ 3~ diphenol). ~he reaction product is believed to ha~e the form -.
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of a polyglyciàyl or diglycidyl ether of bisphenol A (the glycidyl group being more folmal:Ly referred to as ~he

2,3-epoxypropyl group) and thus may be thou~ht of as a poly-ether derived from the diphenol and glycidol (2,3-epoxy-1-. propanol). The structure usually assigned to the resinous . product i8 CH,CCHCH2-O~C(CH3)Z~O-Cll?

. 10 CH~CHCH2-0 ~ C(CH3)2 . In this formula the glycidyl groups having non-terminal pos.tions in the pol~Jmeric raolecules become 2-hydroxytrimethylene groups, -CH2CH(OH)CH2-.
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A viscous liquid epoxy resin, avera~e molecular .
weight æbout 380, is obtained by reactin~ the epichlorohydrin - in hièh molecular proportion relative to ~he bisphenol A, the reaction product containin~ well over 85 mole percent of the ~ monomeric diglycidyl ether of blsphenoL A ~n = O), whlch may.- 20 be named 2,2-bis[p-(2,3-epoxypropoxy)phen~J13propane, and smaller -. . proportions Or polymers in which n is an integer equal to 1, . 2, 3, etc. The epoxy resin prepolymer utilized in accordance - with the present invention is a product ol` the kind ~ust men-tioned, consisting predominantly of the monomeric dlglycldyl - ether ol bis~henol A (probably at least ~0 mole percent of the: mono~er, although this propor~ion is i~practical to determine), havin~ an average molecular weight below about 400, and having an epoxy e~uivalent weight in the ranGe OI' 170 ~O 200, usually , about 172 to 187. Ref.: Handbook of Epoxy Resins, ~. Lee and ~. 3. ~. Neville, McCraw-H~ll Book Company, 19679 pages ~-2 et seq.
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1~4~3198 ., .
1 on "Synthesis of Glycidyl--type Epoxy Resins", particularly pa~es 2-3 and 2-4 on the synthesis of monomeric diglycidyl .' ~ther of bisphenol A.
. ~ ~ Referring next to the phenol novolaks and cresol novolaks, (B), these products are made, following procedures well known in the phenol-fornaldehyde resin art~ by a conden-sation reaction involving formaldehyde and a commercial grade of cresol (or phenol) in excess amounts, using an acid catal-yst, and yielding liquid or low-fusing.thermopl~stic products.
: 10 Such products are available in epoxidized forms, having aver-age molecular weights in the vicinity of 1,000 and epoxy ; equivalent weights in the range of 160 to 200, frequently .-. about 1'j0-180.
Re~erring to the polyglycidyl ethers of polyhydric alconols, (C), a readily availabie example is the diglycldyl ether of 1,4-butanediol, also named 1,4-bis(2,3-epoxypropoxy)-. butane, having the structural rormula CH2CHCH2-0-(CH~)4-0-C~2CHCH2o .
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~- 20 The epoxy equivalent weight of thi.s compound when pure is 101.

Another diglycidyl ether of a glycol is die~hylene . . .
glycol diglycidyl ether, also named bis~2-(2,3-epoxypropoxy)-e~hyl3 ether, having an epoxy equivalent weight of 109 and ~he ~ struc~tural formula ., ~0\ ' ~0~ ' ~

CE~2cHcH~-o-cH2cH2-o-cH2cH2-o-cH2cHcH2~ ~ ~
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A further exa~nple of a poly~lycidyl ether of a ' polyol i.s a di~lycidyl or tri~lycldyl ether o~ glycerol; the '~ triglycidyl ether is 1,2,3-trls(2,3-epoxypropoxy)propane, wh~le the diglycidyl ethers are 2,3-bls(2,3-epo~ypropoxy)-1-propanol ~ "

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~L~4~198 and 1,3-bis(2,~-epoxypropoxy)-2-propanol. One readily avail-able product is a mixture of the triglycidyl ether with one or both of the diglycidyl ethers, having an epoxy equivalent weight roughly midway between that of the triglycidyl ether3 87, and that of the diglycidyl ethers, 102. It i5 noted that the presence, for example, of the additlonal ether oxygen in diethylene glycol diglycidyl ether, or of the remalning al-coholic hydroxy group in the diglycidyl ethers of glycerol, does not detract from the suitability of these compounds having rather low epoxy equivalent weights as polyglycidyl ethers of polyols in the epoxide blends of the invention.
Referring to the diepoxides of cycloalkyl or alkylcycloalkyl hydrocarbons or ethers, (D), these epoxidic compounds rr~y be illustrated by the following.
A diepoxLde of an alkylcycloalkyl hydrocarbon ls vinylcyclohexene dioxide, more specifically identiried as

3-(epoxyethyl)-7-oxabicyclo[4.1.0]heptane, or 1,2-epoxy-4-.
(epoxyethyl)cyclohexane, having an epoxy equi.valent weight of70 and the structural formula ~_~

~ CHC'H2 A diepoxide of a cycloalkyl hydrocarbon is dicyclo-pentadiene dioxide, more specifically i.dentified as 3,4~8g9~
`~ diepoxytricyelo[5.2.1.02'6]decane~ having an epoxy equivalent weight of 82 and the structural forrnula ,,, ,C/ \ ~ \/

H HH

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1 A diepoxide of a cycloalkyl ether is bis(2,3-epoxy-cyclopentyl) ether, otherwise named 2,2'-oxybis(6-oxabicyclo-- [3.1.0]hexane), having an epoxy equivalent weigh~ of` 91 and the . "
structural formula :~ /o\ /o ~- HC - CH HC - CH

\ / \ ) C C

-: 10 -~. Bis(epoxy~cy-cloallcyl~ ester. In addition to the epoxidic pre-,. polymers (designated A-D) discussed hereinabove, the blend of : epoxide materials includes also, admixed therewith, an ester - having ~wo epoxycycloalkyl groups. This diepoxidic alicyclic ..
ester constitutes at least about 15~ of the weight of the blend, and conveniently may be an ester Or an epoxidized cyclic ~ alcohol and an epoxidized cycloalkanecarboxylic acid. Thus, -:~ a suitable ester of epoxidized cyclohexanemethanol and epoxidized cyclohexanecarboxylic acid is the diepoxide (3,4 epoxycyclo-20 hexyl)methyl 3,4-epoxycyclohexanecarboxylate; this same.ester `- rr~y be indexed under the name 7-oxabicyclo[l~.l.O]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate, and has the formula o~ ¦_~,o . .
Another suitable ester having two epoxycycloalkyl ~roups may be obtained as an ester of an alkyl-substituted (epoxycyclo-alkane)methanol and a dibasic acid, for exarnple, bis[(3,4-epoxy-6-methylcyclohexyl)methyl] adipate, which may be named alter-3 natively bis[(4-methyl-~-oxabicyclo[4.1.0]hept-3-y1)methyl]
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~4~9~3 1 adipate, and which has the formula ` ~ CH 0 C-(CH2)4-C-0-C~l2~ ~

Monoepoxide makerial. The epoxide blend additionally may include a monoepoxide having a viscosity at 23C of less than 20 centipoises, constituting not more than about 15~o of the weight of the blend. Exa.rnples o~ suitable rnonoepoxides are the following:

Propylene oxide (1,2-epoxypropane), C/ \CHCH

Butylene oxide (1,2-epoxybutane), C/H bHC~ CH :~

Allyl glycidyl ether (1.-allyloxy-2,3-epoxypropane), ,0 . CH2=cHcH2-o-cH2cHcH2 Butyl glycidyl ether (l-butoxy-2,3-epoxypropane), ';. /\ :
CH3(cH2)3-o-cH2cHcH2 Glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane), o CH2CHCH2-0 ~ ~

It will be appreciated that more than one such monoepoxidic compound may be utiliæed, provided that together these Inonoepoxides do no~ exceed the specified proportion of the weight of the epoxide blend or of the polymerizable com-position. A readily available product is a rnixture of ethers : of the structure /C
CH2CHCH2-0-R~
,, 48~9~
where R is alkyl, that is, glycidyl alkyl ethers. One such mixturc cont~ins predominantly cJ:Lycidyl-octyl ether an~
decyl glycidyl ether, while another contains pr~dominalltly dodecyl glyci~yl ether and ~31ycidyl tetra~3~y1 eth~r.
- Still anotller uscul type of molloel~oxi(le material is a polyolefin te.y., polyethylene) epoxide. Such epoxides ~; are exemplified by epoxidized, low molecular weight by-products of the polymerization of ethylene, which may be separated as mixtures high in l-alkanes in the range from about 10 to 20 carbon atoms, that is from about l-decene to about l-eicosene.
Epoxidation then provides mixtures of the corresponding 1,2-., , epoxyal~anes, examples being mixtures high in thc 1,2-~poxy derivatives of alkanes having 11 to 14 carbons, or having 15 to !
18 carbons.
Initiator. The blend of epoxide materials may be utilized promptly upon mixing for forming a body, film, or coating of - desired shape and the curing thereof effected at once or later, or both of the shaping and the curing may be carried out at a ~; later convenient time or different place. ~ polymerization :' initiator may be mixed into the body in a form which is immediat-' 1 ely active, so that polymerization commences during the mixing , and is completed within a few minutes. For many shape.s such - mixing cannot be achieved after carrying out the shaping, for : -example after making a coating, and rapid polymerization would ' interfere with or prevent the shaping. Accordingly, the - initiator conveniently is mixed with the blend, to ~orm a poly-merizable composition, with the initiator in an inactive condi-tion.
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4~9~3 .:' j ; i ~adiation-sensitive catalyst precursors are cliscussed hereinbelow. Catalyst precurso:rs ordinarily will be present in the polymerizable compositions of the invention in arnounts ranging from about 0.5~ to about 2% of the total weight of the - composit.ions less than 0.1~ or more than 5~ selclom being called .
for. The presence of several percent by weight, for example, :
; of a catalyst precursor causes only a slight dilution of the :
epoxidic materials of the composition, so that the approximate , ~ limits specified hereinabove for the weight proportions of the various epoxides in the epoxide blend ordinarily are not ~ ~ chanyed substantially, when calculated as weic~ht proportions of ; the entire composition, by the addition of a catalyst precursor.
..,, Suitable radiation sensitive catalyst precursors :
decompose to provide a Lewis acid upon application of energy.
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1 The energy required for effective decomposition likewise may be therrnal energy, applied sirnply by heating, or may be energy applied by bombardment with charged particles, notably by ~`~ high-energy electron beam irradiation. However, the catalyst precursors described hereinbelow are primarily photosensitive, and the required energy is imparted by actinic irradiation, which is most effective at those regions of the electromagnetic spectrum at which there is high absorption of electromagnetic energy by the particular catalyst precursor used. More than one of these types of energy may be applied to the same system; e.g., ultraviolet light irradiation followed by ` electron beam irradiation, and post~heating also may be employed, although irradiation ordinarily can effect a s~itable cure.
- Preferred photosensitive Lewis acid catalyst precursors are aromatic diazonium salts of complex halo-genides, which decompose upon appllcation of energy to re-lease a halide Lewis acid. The aromatic diazonium cation may be represented generally as [Ar-N_N], where the aryl group Ar, whlch may be alkaryl hydrocarbon group, is bonded to the diazonium group by replacing one of the hydrogen atoms on a carbon atom of the aromatic nucleus, and where the aryl group ordinarily carries at least one pendant substituent for greater stability of the cation. Thus the pendant substituent may be alkyl, or another substituent, or both. The complex halogenlde anion may be represented by [MXn~m] -. Thus, the photosensitive salt and its decom-position upon actinic irradiation may be depicted as follows:

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~ ~48~913 [Ar-N-N~m [MXn+m] hv _ mAr-X + rnN~ + MXn, (I) ~

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where X is the halogen ligand of the complex halogenide, M
; is the metallic or metalloid central atom thereof, m is the net charge on the complex halogenide ion, and n is the num-ber of halogen atoms in the halide Lewis acid compound re-leased. The Lewis acid halide MXn is an electron pair acceptor, such as FeC13, SnC14, PF5, AsF5, SbF5, and BiC13, which upon suitable irradiation of the diazonium complex salt is released in substantial quantit~es and initia-tes or catalyzes the poly-merization process~ wherein the monomeric or prepolymeric material is polymerized or cured as the result of the actinic irradiation.
The catalyst precursors in the form of` photo-sensitive aromatic diazonium salts of complex halogenides may be prepared using procedures known in the art. Thus, for example, chlorometallic halogenide complexes may be prepared ; in accordance with the method set forth by Lee et al in Journal_of the American Chemical Society, 83, 1928 (1961).

Exemplifying a procedure of general utility, arenediazonium hexafluorophosphates can be prepared by diazotizing the corresponding aniline with NOPF6, made by combining HCl and NaN02 with subsequent addition of hydrogen hexafluorophosphate (HPF6) or of a hexafluorophosphate salt~ or they can be pre-- pared by addition of a hexafluorophosphate salt to another diazonium salt to effect precipitation. As a further example, various morpholinoaryl complexes~ containin~ the group CH2CH~-0-CH2CH2-N ~ , can be prepared either from the ani-7' , U4819~3 1 line derivative or by adding an aqueous solution of a metal salt Or the desired complex halogenlde to a solution of morpholinobenzenediazonium tetrafluoroborate.
An illustrative selection of aromatic diazonium , .
salts of complex halogenides is listed ln Table I. Many o~
the salts listed have been found to be well adapted or superior ~or use as latent photosensitive polymerization lnitiators in the epoxlde polymerization process and polymerizable epoxidlc co~positions Or the present invention, based on thermal stability, on solubility and stability in the epoxy formu--lations used, on photosensitivity, and on ability to effect polylnerization with the deslred degree of curing after adequate actinic irradiation. Following the name Or each aromatic diazonium halogenide is its rneltlng point or decom-position te~.perature, in degrees centigrade, and wavelengths of electromagnetlc radiatlon, in nanometers, at which it ..i .
- exhibits absorption maxima.
~, The melting points given in Table I were deter-mined generally by the usual visual capillary tube method;
; 20 in most cases discoloration began below the observed rnelt-; .
~ ing point tempera-tuxe with frothing decoMposition at that -~ te,lperature. In some cases melting points or exotherms ~ were deier~ined also by differential thermal analysis under :J; nitro~en gas, and the te~pelatures so deterlnined are given in parentheses. The wavelen~ths Or absorptlon maxima in the ultraviolet-to-visible range were deter~,ined with the ;, di~zonium complex salt dissolved in acetonltrile.

, .
~ 30 1~48~L98 TABLE I

:~ . M.P., Abs'n Max., C. nm.
: 2,4-dichlorobenzenedlazonium 62-64 259, 285, 360 ~ tetrachlororerrate(III) : p-nitrobenzenedlazonium tetra- 93-95 243, 257, 310, -.- chloroferrate(III) 360 p-morpholinobenzenediazonium 121.5 240, 267, 313, 364 tetrachloroferrate(III) 23 4-dichlorobenzenediazonium 190 285 ; hexachlorostannate~IV) p-nitrobenzenediazonlum hexa- 126 258, 310 chlorostannate(IV) .2,4~dichlorobenzenediazonium 152 285, 325-340 tetrafluoroborate . (shoulder) p-chlorobenzenediazonium hexa- 162-164 273 fluorophosphate 2,5-dichlorobenzenediazonlum dec. 140 264, 318 ~- hexafluorophosphate 2,4,6-trichlorobenzenediazonium 240-250 29l~ 337 hexafluorophosphate 2,4,6-tribromobenzenediazonium 245-260 306 -.. ; hexafluorophosphate . ~.......... . . .
~ p-nitrobenzenedi.azonium hexa- 156 (lf8) 25~, 310 . Iluorophosphate o-nitrobenzenediazonium hexa- 161.5 .;........... fluorophosphate ~ . . . .
4-nilro-o-toluenediazonium hexa- 123 (138) 262, 319 ~luorophosphate (2-methyl-4-nitro-benzenediazonium hexa~luorophosphate) ~-nitro-p-toluenediazonium hexa- l6l1-16~ 286 -.~ rluorophosphate (4-methyl-2-: nitro-benz~nedlazonium hexafluoro-phosphate)

5~ 6-nitro -~,4-xylenediazonium hexa- 150 237, 290 . rluorophosphate (2,4-dimethyl-: 6-nitrobenzenediazonlum hexa-.- . fluorophosphate) p-morpholinobenzenedia~onium hexa- 162 (181) 377 ~luorophosphate . . i .~
. .

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~al48198 TABLE I (continued) M.P., Abs'n Max., C nm.
4-chloro-2,5-dimethoxybenzenedia- 168~169 243 (shoulder3, zonium hexafluorophosphate (198-208) 287,392 2,5-dimethoxy-4-morpholinobenzene- Above 266, 396 diazonium hexafluorophosphate 135 2-chlo~o-4-(dimethylamino)~5-meth- 111 273,405 oxybenzenediazonium hexafluoro-phosphate 2,5-diethoxy-4_(p-tolylthio)ben- 147 (150) 223 (shoulder), zenediazonium hexafluorophosphate 247, 357, 397 (2,5-diethoxy-4-(p-tolylmercapto)-benzenediazonium hexafluorophosphate) 2~5-dimethoxy-4-(p-tolylthio)ben- 146 (155) 358~00 zenediazonium hexafluorophosphate 2,5-dimethoxy-4'-methyl-4-biphenyl- 167 405 diazonium hexafluorophosphate (2,5-dimethoxy-4-(p-tolyl)benzene-- diazonium hexafluorophosphate) .
- 2,4',5-triethoxy-4-~iphenyldiazonium 136 265, 415 hexafluorophosphate (2,5-diethoxy-4-(p-ethoxyphenyl)benzenediazonium hexafluorophosphate) 4-(dimethylamino)-1-naphthalenedia- 148 280, 310, 410 zonium hexafluorophosphate p-nitrobenzenediazonium hexafluoro- 141-144 257, 310 ; arsenate (V) (161) p-morpholinobenzenediazonium hexa- 162 257, 378 ` fluoroarsenate(V) (176-177) 2,5_dichlorobenzenediazonium hexa- 161-162.5 238, 358 fluoroantimonate(V3 ` p-nitrobenzenediazonium hexafluoro- 140-141 257,308 antimonate(V) p-morpholinobenzenediazonium hexa- 153 254, 374 fluoroantimonate(V) (177.5-180.5) - 2,4-dichlorobenzenediazonium hexa- 178-180 279, 322 (shoulder chloroantimonate(V) 2,4-dichlorobenzenediazonium penta- 193.5-195 285,313 chlorobismuthate(III) o-nitrobenzenediazonium pentachloro- 166.5-168 285, 313 bismuthate(III) .

: 1~48::~91~

1 The catlonic initiators or catalyst precur~ors listed hereil~above are solids. It usually is posslble to dissolve such in~re~ients in one or more of the polymerizable ingredients maklng up the epoxide blend which is utllized ln the polymerizable compositions of the present invention. However, ~t frequen~ y is more convenient for mixlng purposes to pro-; ~ide such an ingredient for the mixing operatlon already dis-solved in a solvent. Thus the use of a small amount of a solvent medium such as acetone or anisole often is convenient for introducing the solid additive and facilitatlllg its solu-tion and distribution throughout the epoxide blend. It has been found that co~mercial propylene carbonate (a cyclic pro-pylene ester of carbonic acid3 probably identified as primarily 4-methyl-1,3-dioxolan-2-one) makes a good solvent for the aromatic dlazonium complex salts, and the propylene carbonate . , .
so used is completely miscible wlth epoxy resins. For ex-ample, propylene carbonate may make up between approxl~ately 1% and 2-l/2~ by weight OI' the entir~ ~olymerizable composition.
To avoid substantially the disadvantages of utiliz-ing an inert solvent medium, the total amounts o~ any solvents which do not participate in the polyrner~zation reactions, ~n-cluding a solvent such as propylene carbonate and any volatile solvents present, should be kept below about 4~ by weight. In particular, unpolymerizable volatile solvents bolling below ~bout 190C should be kept within this approximate limit of 4% by welght to avoid the substantial evolution of waste gases during appllcation and polymerlzation of the polymerizable colnposition. Wlthln this approxlmate li~it, the presence Or solvents is not ~ound to change the essential character Or the epoxide blends and polymerizable compositions of the present invention.

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1 Re~erring to equation I hereinabove showing the photolytic decomposition of a catalyst precursor, the halide Lewis acid t~n released reacts with the epoxidic ma~erials of the blend with a result exemplifled by the following:
ArN2M(Xn+l) + monomer I-~d-iation~ polymer. (II).

- A similar result is achieved by heating the monomeric or pre-polymeric epoxide blend containing, for example, a heat-sensitive `~ . initiator such as boron rluoride ethylamine to release a Lewis .. - . .
acid, in that case BF3. The cationle catal~st is believed to -~ 10 act by cleaving a carbon-oxygen epoxy bond, initia~in6 ~rowth ; .of a polymeric chain or permitting formation o~ a cross-linkage.
;j~ A general application of the process embodied by equations I
- and II can be as follows: a ~iazonium complex salt, for example, ~s identi~ied hereinabove~ ls admixed with the epoxide blend.
q~he mixture is thereafter coated on a suitable substrate such ` QS a metal plate, plastic, or paper, and the substrate is ex-posed to ul~raviolet or electron beam radiation. On exposure the diazonium compound decomposes to yleld the Lewis acid cat-2~ alyst~ which inltiates the polyrnerizatlon of the epoxy monomer.The resulting polymer is resistant to most solvents and chemicals.
; - The source of radiation ~or ef~fecting production of the epoxidic polymer can be any suitable source, such as the ultrsvlolet actinic radi~tion produced ~rom a rnercury, xenon, .
or carbon arc lamp, or the electron beam produced in a suitably evacuated cathode ray gun. The only limitation placed on the radiation source used is that lt must ha~e an en~r~y level at tha irradlated film suf~lcient to impart to the polymerizable system energy at an intenslty hlgh enough to reach the decom-3 position level of the photosensltive compounds. As prevlously "
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~ , . ~.

' ~4 noted, t~ie wavelength (~requency) range of actlnic radiatlonis chosen to obtain sufricient absorption Or energy to excite the desired decomposition.
For an imaging system~ the rnixture of epoxides and cationic initiator is coated on a metal plate, and the plate is exposed to ultraviolet light through a mask or nega-tive. The light initiates polymerization which propagates rapidly in the exposed image areas. The resulting polymer in the exposed areas is resistant to man~ or most solvents --.
and chemicals, while the unexposed areas can be washed awa~ with suitable solvents to leave a reversal image of an epoxy polymer in this embodiment.
The polymers produced by the polymerizing pro-; cess of the present invention are useful in a wide variety of applications in the ~ield of coatin~, decoratlon of sub-strates, and graphic arts, due to their superior adhesion to metal and paper surfaces, excellent resistance to most sol-vents and chemicals, and capability of forming high resolution images. Among such uses are photoresists for chemical milllng, 2G gravure images, of~set pla-tes, stencil-maklng, microimages for printed circuitry~ thermoset vesicular irnages, microimages for information storage, decora-tion o~ paper~ glass, and packages, and light-cured coatings.
The procedures for mixing the epoxide blends and ; curable compositions of the present lnvention are relatively simple. The several monomer and prepolymer resins are combined with each other and with the catalyst precursor, serially or in one mixing operation, in suitable blending or mixlng apparatus, ; such as a conventional propeller stirrer. The catalyst pre-cursor thus may be dissolved directly in the premlxed i. .

. - 1 9-;- --.~;
~413198 .' 1 epoxide blend, or in an epoxide component thereo~ having good ~ solvent properties and low viscosity which thereafter is blended .. :- with the other epoxides to form the blend. Alternatively, ~ the cationic lnitiator may be mixed preli.minarily in a small -. proportion of a volatile or nonvolatile solvent medium, as discussed hereinabove, and then combined with the polymerizable ~¢~ rr~terial.
.
The amount of catalyst precursor employed should :~ be sufficient to insure complete polymerization. It has been ;: .
;.~ 10 found that quite satisfactory resul~s are ob~ained by providing . ..
a diazonium complex saltg for example, in amount by wei6ht from about 0.5~ to about 5% of the catalyst precursor relative to the weight of` the polymerizable epoxide material present, about or less OI` the precursor being amply effective with most epoxide-catalyst precursor systems. To be satisf`actorily e~fective, the cationic initiator present in the polymerizable composition should be soluble in the epoxy resin blend, should not reac~ with the epoxides at room temperature in the absence of activating radiation, but should decompose rapidly .. . .
.~ 20 ~n exposure to actinic radiation or electron beams of` suffi-cient energy, to liberate a cationic agent for initiating poly-.:~
merization of` khe epoxide materials.

It may be desirable to include in the epoxide blend, or in the polymerizable composition made up with the epoxide '~ blend~ an inert pigrnent or fil.ler, which may be present in even `- a major proportion by weight, or srnall amounts of` inert non-~ volalile liquids such as mineral oil, sof`teners, surfactants, .- or like adjuv~nts. Inclusion of such substantially inert ingred-i.ents usually makes advisable a proportionate increase in the .;

;
. , ' `' :"

. . ~ ~
~48~8 optimum amount of catalyst precursor used. ~evertheless, the precursor needed rarely exceeds 5% of the entire weight of the composition. It will be appreciated that the presence of such additional inert ingredients does not substantially affect or alter the essential characteristics of the epoxide blend or oE
the polymerizable compositions as regards their intended util-izations or essential properties.
The following examples will serve further to illustrate the present invention.

A blend was prepared of the following epoxide mat-erials, in parts by weight:

1,4-Butanediol diglycidyl ether 1,000 (50.0%) (3,4-Epoxycyclohexyl)methyl 1~000 (50.0%) 3,4-epoxycyclohexanecarboxylate ; An amount equal to 12 parts by weight of a ca~alyst precursor, 2,5-diethoxy-4-~p-tolylthio)benzenediazonium hexa-fluorophosphate, was dissolved in the resin blend, constituting 0.60% of the weight of the resulting polymerizable composition.
A small quantity of this light-sensitive composition was spread by hand draw_down in a thin film over an aluminum plate and exposed to a 3~0-watt high pressure mercury arc lamp at a distance of 2 inches. Polymer~zation co~nenced immediately upon exposure to the ultraviolet radiàtion, and within ~0 seconds the coating on the aluminum plate had cured to a hard finish.
This formulation including a polyglycidyl ether of a polyhy-; dric alcohol is well suited for application to metal substrates using conventional production roller coaters. Printed or decorative maeter ~ay be provided by applyin~ poreions Oe such , . .

.. , ~

;.:
a mixture containing appropriate pigments to predetermined areas of the surface of the metal substrate, or the entire surface `;~ may be coated therewith, followed by the application of energy through irradiation to cure the composition transferred to the substrate and produce the desired coated or imprinted metal ; product. ;

` EXAMP E 2 An epoxide blend was prepared, using 20 milliliters ;- of each of the following materials to provide a mixture contain-ing closely equal parts by weight of the two materials:
1,4-Butanediol diglycidyl ether (50% approx.) -(3,4-Epoxycyclohexyl)methyl (50% approx.) 3,4-epoxycyclohexanecarboxylate A solution was made by dissolving 705 grams of the latent initiator p-chlorobenzenediazonium hexafluorophosphate in . 50 millilters of acetonitrile. A 1 ml portion Qf this solution, containing 0.15 g of the initiator complex salt, was mixed into :
the blend obtained by mixing the above-specified volumes of epoxides, thus providing the initiator therein in amount equal to approximately 0~33% of the total weight, and ah~so providing therein the acetonitrile solvent in amount equal to approximately :.
~ 1~55% of the total weight. The beneficial effect of such small ~ .
addition of acetonitrile in inhibiting premature gelation of the polymerizable epoxide composition is disclosed and claimed in my Ganadian Application Serial No~ 166,412 filed March 19, 1973 entitled Controlled Polymerization Process and Stabilized Polymerizable Compositions and assignèd to the same assignee as that of the present application.

A portion of the composition prepared as above was 30 applied to metal and plastic substrates in the form of an aluminium sheet and a sheet of polyethylene plastic material, using a drawbar (No. 3) to obtain even coatings of the order of 0~0005 ."~ .
., ;:, - : ' ' '~ ' '' . , '. ' , , ` , . . ': :

.~

~L0~319~ ' inch thick when wet. The coated sheets were exposed to the rad-iation from a 360-watt mercury arc lamp at a distance of 3 inches - for 1 minute, giving hard cured coatings on both metal and plas-tic substrates.

The following epoxides were blended:

Vinylcyclohexene dioxide 22 g (52.4%) - (3,4-Epoxycyclohexyl)methyl 20 g (47~6%) 3,4-epoxycyclohexanecarboxylate Another l-milliliter portion of the sa~e solution of latent initiator, prepared as described in Example 2, was ~; added to the blend of vinylcyclohexene dioxide with the bis--~ (epoxycyclohexyl) ester. This addition provided 0.35% by weight of initiator and approximately 1.6% by weight of acetonitrile in the resulting polymerizable composition. Portions of this composition likewise were coated on metal and plastic substrates and irradiated under the mercury arc for 1 minute~ again giving hard cured coatings on both the metal and plastic surfaces, EX~MPLE 4 .: ~ .
An epoxide blend was made up of the following epoxid~s in parts by weight:

Vinylcyclohexene dioxide 2 parts (28.6%) (3,4-Epoxycyclohexyl)methyl 5 parts (71.4%) 3,4-epoxycyclohexanecarboxylate To 10 g of~-this blend there were added 60 mg (0.60%
of the total weight) of 2,5-diethoxy-4-(p-tolylthio)benzenedia-zonium hexafluorophosphate, and stirring was continued until dis-solved. The resulting light-sensitive formulation was used to coat ~ .

` -23-i ~ , .
,, 'i .
.

: ' '' ,. ,, : .. , ~, )4~3~9~3 1 plate o~ chromated steel, using a No. 3 drawbar. The steel pl~te was exposed to a 360-watt mercury arc at a distance of ? inches for 2 seconds, then placed in an oven at 110C for 10 minutes. The coating cure~ to a hard,glossy protective finish. To test ~dhesion the coated plate was immersed for 30 minutes in a hot water bath maintalned at 1C, removed, blotted dry, scratched wlth a sharp blade ancl impressed with a piece of highly adhesive plastic tape. Pulling the tape off sharply failed to remove the coating from the metal plate.

The bis(epoxycyclohexyl) ester may provide a very high proportion of the epoxide materials, as illustrated by the following blend: ~

Prepolymer consistlng sub- 40 g (10~) stantially of diglycid-yl ether of bisphenol A

(3,4-Epoxycyclohexyl)methyl 360 g (90%) 3,4-epoxycyclohexanecarboxylate The prepGlymer product used was specified to nave a viscosity at 25~C ln Ihe range of ~,500-9,500 cps and an epoxy equivalen~ weight of 180-1~8. To this weight of the blend was added a solution o~ 4 g (0.97~ of the total wei~ht) of p-chlorobenzenediazonium hexa~luorophosphate in 8 ml (9.65 g, or 2.33~) o~ propylene carbonate. The resulting mixture was placed in the ~ountain Or a Heidelberg printing press of the dry ofPse~ type and applled to paper as a ~hln coatin~. The paper was then placed on a conveyor passing beneath two 1200-wntt hi~,h-pressure mercury arcs. Shortly after exposure to the mercury arcs, the coating had cured to a hard, g]ossy rinish.

_;~1~ _ :

. . .
.

v~ ~
~415 ~IL9~ , Examples 6 and 7 illustrate epoxide blends near the upper limit of the proportion of the prepolymer material~

The following epoxide blend was prepared, in parts by weight:
Prepolymer consisting sub- 720 parts stantially of diglycid--~ yl ether of bisphenol A
Epoxy phenol novolak 90 parts 810 parts (81.8%) (3,4-Epoxycyclohexyl)methyl 334-epoxycyclohexanecarboxylate180 parts (18.2%) The diglycidyl ether of bisphenol A was specified to have a viscosity of 6,500-9,500 cps at 25C and an epoxy equivalent weight of 180-188; the epoxidized phenol novolak ; had a viscosity at 52C in the range of 1,400-2,000 cps and an epoxy equivalent weight of 172-179. Also included in this ~- epoxide blend as a surface active adjuvant were 9 parts of ~in- -eral oil (making 999 parts by weight, and becoming 0.87% of the total weight of the polymerizable composition). The polymer-izable composition was completed by adding, to a 400-gram portion of the above composition including mineral oil, 4 g (0.97% of the total weight) of p-chlorobenzenediazonium hexa-fluorophosphate in 8 ml (9.65 g, or 2.33% of the total weight) of propylene carbonate. The epoxide blend of diglycidyl ether of bisphenol A and novolak constituted 95.8% of the total weight, or 96.8% including the benzediazonium complex salt as the cationic initiator.
The clear varnish thus prepared was applied to paper as a coating by a dry offset printing press. The coated 30 paper was placed on a conveyor moving at 500 feet per minute and passing beneath two 1200-watt high pressure mercury arcs.

,:

i(~4~31953 Immediately after exposure the varnish already was dry to the touch and gave a hard glossy finish over the paper.

EE~rPLE 7 A blend of epoxy resins was prepared by mixing the following, in parts by weight:
Prepolymer consisting sub- 600 parts stantially of diglycid-yl ether of bisphenol A
Epoxy phenol novolak 78 parts 678 parts (85.5%) (3,4-Epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxy-115 parts (14.5%) late The above epoxides were the same products used ; in the epoxide blend of Example 6. To a fraction of this resin blend was added 1% by weight (7.93 parts, or 0.96% of the total weight~ of p-chlorobenzenediazonium hexafluorophosphate dissolved in an amount of methyl ethyl ketone equal to 3% by weight of the fraction of resin blend (23.8) parts, or 2.88% of the total weight). This light-sensitive formulation then was applied to paper in a thin film and exposed to a 1200-watt high pressure mercury arc lamp for 0.5 second at a distance of 2 inches, The resin film cured to a hard, non-tacky finish.

EXAMPLE ~
The following resin blend was prepared, in parts by weight:
Epoxy phenol novolak 100 (33.3%) (3,4-Epoxycyclohexyl)methyl 200 (66.7%) 3,4-epoxycyclohexanecarboxylate The novolak had a viscosity in the range of 1,400-2,000 cps at 32C and an epoxy equivalent weight df 172-179.

Along with these epoxides there also were included 2.3 parts (0.76% of the total weight) of the catalyst precursor 2,5-di-ethoxy-4-(p-tolylthio)benzenediazonium hexafluorophosphate and mixing was continued until a homogeneous solution was ob-tained.
A roller coated was used to apply portions of this solution to a caly-filled paper substrate and also to another paper substrate already carrying a printed ink decoration.
The coated paper were passed beneath a 360-watt high pressure mercury lamp for 10 seconds at a distance of 3 inches. The coatings cured to an odorless finish having high glossl On stacking the coated sheets procued as des-~cribed in Example 8~ a slight tendency was observed for the sheets to adhere to each other. This tendency was overcome by a rather small modification of the epoxide blend, in which was included a monoepoxide, in the form or 1,2-epoxybutane, having a viscosity at 23C of less than 20 cps. This modified formulation is described in Example 9, and the examples follow-ing Example 9 illustrate a variety of formulation in which the epoxide blend includes such a monoepoxide in addition to the prepolymer material and the bis(epoxycycloalkyl) ester.

A modified resin blend~ based on the formulation of Example 8, was mixed to include the following epoxides, in parts by weight:

Epoxy phenol novolak100 parts (3209%) (3~4-~Epoxycyc~loh-exyhl)methyl ~ 200 parts (65~8%) 3,4-epoxycyclohexanecarboxylate 1,2-Epoxybutane 4 parts (1.3%) .

~g8~98 As with Example 8, 2.3 parts (0.75% of the total weight) of 2,5-diethoxy-4-(p-tolylthio)benzenediazonium hexa-fluorophosphate were mixed thoroughly in with the epoxide blend.
When portions~of the resulting formulation were coated on paper and cured as in Exa~ple 8, the coated paper sheets showed no tendency to adhere when stacked.

The following epoxides-were blended (parts by weight):

Epoxy phenol novolak16 parts (59.3%) (3,4-Epoxycyclohexyl)methyl8 parts (29.6%) 3,4-epoxycyclohexanecarboxylate 1,2-Epoxybutane 3 parts (11.1L) The novolak had a viscosity in the range of 1,400-2,000 cps at 52 C and an epoxy equivalent weight of 172-179.
To 10 g of the above resin blend there was tho~oughly admixed 0.1 g (0.99% of the total weight) of 2,5-diethoxy-4-(p-tolyl-thio)benzenediazonium hexafluorophosphate~ The resulting light~sensitive coating formulation was applied to paperboard, using a roller coater, and exposed to a 360-watt high-pressure mercury arc. ~ithin 25 seconds the coating had cured to a hard flnish showing a high gloss and good adhesion to the paper-board.

Another blend of epoxides was made of the following, in parts by weight:

Epoxy phenol novolak 160 parts (59.3%) (3,4-Epoxycyclohexyl)methyl 80 parts (29.6%) 3,4-epoxycyclohexanecarboxylate Alkyl glycidyl ether in 30 parts (11.1%) which alkyl groups are pre-dominantly octyl and decyl -2~-: . . . .
~: .' , ,. ' ' !

~48~98 The novolak product of Example lO was used also ; in the above blend. To 200 parts by weight of this resin blend were added 2.1 parts by weight ~1.0%) of 2,5-diethoxy-4-(p-tolylthio)benzenediazonium hexafluorophosphate dissolved in 5 parts (2.41%) of acetonitrile. This light-sensitive coat-ing formulation was applied to paperboard using a roller coater.
The coated board was exposed to a 360-watt high pressure mercury arc, for 5 seconds, which caused the coating to cure to a hard, glossy finish.

An epoxide blend was mixed as follows (parts by weight):

Epoxy phenol novolak 10 parts (71.5%) (3,4-Epoxycycloh~xy~methyl 3 parts (21.4%) 3,4-epoxycyclohexanecarboxylate 1,2-Epoxybutane 1 part (7~1V/o) Again a novolak was used having a viscosity~ in the range of 1,400-2,000 cps and an epoxy equivalent weigh of 172-179. In a 20 ml portion of the above blend there was dissolved 0.5 g of2,5-diethoxy-4-(p-tolylthio)benzenediazonium hexafluorophosphate, which made up approximately 1.4% of the total weight of the resulting photosensitive composition. The resulting solution was applied to the surface of a coating-holdout paper, clay-filled to prevent rapid penetration, and to another paper substrate whose surface was covered with a printed ink deco~tion. These coated papers were exposed to a 360-watt high pressure mercury lamp at a distance of 3 inches for 10 seconds. The coatingsccur~d to a hard, glossy~ prac-tically odorless finish.

.' , .

~48~9~3 ' i EXA~PLE 13 As exemplifying a polymerizable composition curable by application of thermal energy alone, that is, by heating the composition as coated or otherwise applied, a resin blend was prepared by mixing the following epoxide materials (in parts by weight):

Prepolymer consisting sub- 20 parts (60.6%) - stantially of diglycid-~ yl ether of bisphenol A
; ~3,4-Epo,x~c~ycl~ohexyl?methyl ~ 10 parts (30.3%) ~,4-epoxycyclohexanecarbo*ylate Alkyl glycidyl ether in 3 parts (9.1%) which alkyl groups are predominantly dodecyl ; and ~etradecyl The bisphenol A diglycidyl ether prepolymer used had a viscosity at 25C in the range of 4,000-6,000 cps and an epoxy equivalent weight of 172-178. To 100 g of this resin blend there were added 2 g (1.96%) of boron trifluoride mono- -ethylamine complex, and the mixture was stirred with gentle war~ing until a homogeneous solution was formed.
Aliquots of 5 ml each were withdrawn from this solution and immersed in an oil bath at various temperatures.
The timre required for the formulation to harden wasnoted, with the~following results:
Bath Temperature, CTime to Harden~ Seconds 160 More than 120 A few drops of the cataly~ed formulation were placed on a steel sheet and drawn down to a thin film with a glass rod. The steel sheet was placed on a hot plate. Within 5 seconds the film had hardened, providing a g~ossy, protective coating which showed good adhesion to the steel sheet.

: ' ' . ' ,, i'. ' : ' ' ' 3L~9L8~L98 1 EXA~IPLE ]4 An epoxide blend was made as follows:
Vlscosity Epoxy Parts at 25~C, EquivO by Epoxlde Material Cps Wt~ Wei~ht _ _ Prepolymer consis~i.ng sub-stantially of diglycld- 6500-9500 18218 (51.4~) yl ether of blsphenol A
~3,4-Epoxycyclohexyl)methyl 275 13912 (34 ~ 3%) 3,4-epoxycyclohexanecarboxylate Alkyl glycidyl ether in 8 2635 (14-3~) whlch alkyl groups are predominantly dodecyl and tetradecyl A 400 g aliquot of this blend was measured out, lV and to it were added 10 ml of a 1.0 molar solution ol a light-~ensitive cationic initiator, namely p-chlorobenzenediazonium hexafluorophosphate, in acetone. This addition provlded approx-imately 0.7% of the latent initiator and approximately 1 6% of the volatile solvent, expressed in percentages of the total weight. A coating of this formulatlon may be cured readlly by exposure to radiatlon ~rom a mercury arc~

~. .
A blend of epoxide resins was prepared by mix-lng the following materials, in parts by weieht:
Prepolymer conslsting sub- 4 parts (57.1%) stantially of diglycid~
yl ether of bisphenol A
(3,4-Epoxycyclohexyl)methyl 2 parts (28.6%) 3~4-epoxycyclohexanecarboxylate Alky~ gl~cldyl ether in 1 part (14.3%) which alkyl groups are pre-dominantly octyl and dec~l Thle dlglycldyl ether of blsphenol A has an epoxy equivalent welght o~ ~pproxlmately 187 and a vlscosity at 25C specl~ied to be within the range of 5,000 to 6,400 cps.
To an amount o~ th:ls epoxlde blend weighing 350 g there were added 2.8 g (0.79~) Or ~ latent c~tionic polymerlzation lnitiator 3o ln the form Or p-nitroben7enediazonium tetrafluoro~)orate. The - ! 104~3198 , 1 viscoslty of -the resulting composltion upon mixlng waS 410 Cp8 at 25C. Polymeri~ation of coatlngs of this compositlon ls lnltiated by irradlatlon with ultravlolet llght.

.
The ~ollowing resin blend was mixed:
- Vinylcyclohexene dioxide 10 parts (43.5%) (3,4 Epoxycyclohex~l)methyl 10 parts (1~3.5 3~4-epoxycyclohexanecarboxylate 1,2-Epoxybutane 3 parts (13.0~) In 10 g of thls blend there were dissolved 60 mg (o.60%) of 2,5-diethoxy-4-(p-tolylthio)benzenediazonium hexa-~luorophosphateO The resulting light-sensitive solution was spread in ~ thin film over the surface of a chromated steel plate, exposed to a 360-watt mercury arc for 2 seconds, and then heated in an oven at 110~C for 10 minutes. The coating at the e~.d of 'hls t~e was ha~d and displ&yed excellent adheslon to the metal plateO

. .
~ nother resin blend was made, as follows:
Yln~lcyclohexene dioxide 16 parts ~1.0~) (3,~-Epoxycyclohexyl)methyl 20 parts ~51.3 3,4-epoxycyclohexanecarboxylate ~J Alkyl glycidyl ether in3 parts (7 7%) which alkyl groups are pre-dominantly octyl and decyl A 60-mg weight o~ 2~5-diethoxy-4-(p-tolylthio)-benzenediazonium hexarluorophosphate was dlssolved ln a 10~gram weight ~ra~m ~rom this resin blend. Thin fllms of the resulting llght-sensitive coating formulation were applied to sheets of alumlnum and Or chromated steel. A~ter a 2-second e~posure to - a 360-watt high pressur~ mercury arc~ the coated metal sheets were baked for 10 minutes at 110C. The coating cured to a hard, tough finish show~ng good adhesion to the alumlnum and chrom~ted ~teel substrates.

_~z_ .
. .

~8~18 The following blend including two epoxidic pre~
polymers was prepared:

Prepolymer consisting sub- 6 g ~ stantially of diglycid-- y~ ether of Bisphenol A
Epoxy phenol novolak 6 g ; 12 g (21.4%) ; (3,4-Epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxylate 40 g (71.5%) Allyl glycidyl ether 4 g (7.1%) The diglycidyl ether of bisphenol A was specified to have a viscosity of 5,000-6,500 cps at 25C and aiminimum epoxy equivalent weight df~il78, the novnIa~:product~was~speci-fied to have a viscosity of 1,400-2,000 cps at 52C and an epoxy ; equivalent weight between 172 and 179. When the epoxide blend ` described above was prepared, the mixture included also 392 mg of p-chlorobenzenediazonium hexafluorophosphate, Pqual to 0.70% of the weight of the mixture. The resulting light-sensitive formulation was applied to paperboard using a roller coater, and the coated paperboard was exposed to two 1200-watt mercury arcs while on a conveyor moving at 480 feet per minuteO The coating cured to a hard, glossy finish.

A large batch of epoxide materials was prepared by blending the following, in the indicated proportions by weigh~:

Epoxy phenol novolak 250 parts Vinylcyclohexene dioxide 25 parts 275 parts (68.75%) BisC(3,4-epoxy-6-methylcy 75 parts (18.75%) clohexyl)methyl~adipate Alkyl glycidyl ether in 50 parts (12.50%) ` which alkyl groups are pre-dominantly octyl and decyl 400 parts ,,, , ~ . . .

.9~3 ' The novolak used in this blend had a viscosity at 52 C within the range of 1,400-2,000 CPS and an epoxy equivalent weight of 172-179. The four epoxide mater$als, blended i n the given proportions, had a viscosity of about 400 CPS at 23CJ
To 400 parts of this epoxide blend were added 20 parts of a 20~b solution of p-chlorobenzenediazonium hexafluorophosphate in acetonitrile, providing therein 4 parts of the catalyst precursor, or 0.95% by weight of the entire polymerizable composition. The remaining 16 parts of acetonitrile, a vola-tile solvent with gelation-inhibiting properties, constituted 3.81% of the weight of the composition.
The catalyzed formulation was applied to a coat-ing-holdout pape~, using a roller coater. The coated paper then was exposed to a 360-watt high pressure mercury lamp at a distance of 3 inches for 5 seconds. The coating was found to have cured to a non-tacky,~high gloss finish and showed good adhesion to the paper.

In another 100 parts by weight of the batch of resin blend described in Example ~ill9 there were dissolved 1.~2 parts of 2,5-diethoxy-4-(p-tolylthio)benzenediazonium hexa-fluorophosphate (1.19% of the total weight).
The solution then was used to coat sheets of a clay-coated paperboard, using a roller coater. The resin-coated sheets were placed on a conveyor blet moving at 500 feet per minute and passed beneath all200-watt high pressure mercury lamp 17 inches in length at a distance of 3 inches.
The coating cured to a non-tacky finish. To(~ test for "blocking", the coated sheets were s~acked and pressed in a hydraullc press , . . . ~ . : .
i' , ' , : ' ~

~Lal48~8 under 10 tons of pressure for 10 minutes. There was no evidence of sticking together. The stacked sheets then were kept under a pressure of 50 pounds for 72 hours. There was no tendency for the sheets so pressed to stick together.

` Another portion of a light-E~ensitive composition was made by dissolving 1 part by weight of the 2,5-diethoxy~4- -(p-tolylthio)benzenediazonium hexafluorophosphate catalyst pre-cursor in another 100 parts of the epoxide batch of Example 19, giving 0.99% by weight of the catalyst precursorO
The resulting solution was used to coat a special paper filled with a polybutadiene latex. After coating, the paper immediately was exposed to a 360-watt high pressur2 mer-cury lamp at a distance of 3 inches for S seconds. The coat ing cured to a high-gloss~ non-tacky finish free of odor.
The same solution was used to coat continuously at a rate of 100 feet per minute a reel of paper 8 inches wide, using a laboratory roller coating machine. The coated web then was passed beneath a 1200watt mercury lamp 17 inchdes long at a distance of 3 inchdes and immediately rewound. The cured finish was glossy, nearly odorless, and showed no tendency to stic~ on rewinding.

A mixture was prepared of the following epoxide materials in the indicated proportions:

9~ ~
Epoxy pehnol novolak 12.50 g Yinylcyclohexene dioxide 1.25 g 13.75 g (68.75%) (3,4-Epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxylate 3.75 g (18.75%) Glycidyl phenyl ether ~ (12.50%) 20.00 g The novolak used had the same specifications as that used in the composition of Example 19~ To 20 g of the above mixture there was added 0.2 g ~0.99%) of 2,5-diethoxy-4-(p-tolylthio)benzenediazonium hexafluorophosphate. The re-sulting light-sensitive coating formulation was applied to paperboard~ using a roller coater, and immediately exposed to a 360-watt high pressure mercury arc for 5 seconds~ The coating, liquid before exposure9 was hard and glossy immediately after exposure.

The following blend of epoxy resins was prepared:

Prepolymer consisting sub 30 parts stantially of diglycid-yl ether of bisphenol A
1,4-Butanediol diglycidyl 3 parts ether 33 parts (66.0%) ~3,4-Epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxylate 15 parts (30~0~/O) Alkyl glycidyl ether in 2 parts (4.0%) which alkyl groups are predominantly dodecyl and tetradecyl The d~glycidyl ether of bisphenol A used in this blend had a viscosity at 25C in the range of 4,000-6,000 cps and an epoxy equivalent weight of 172-178. To 40 g of this resin blend were added 0.4g (0.99%~ of 2,5-diethoxy-4-(p-tolyl-thio~benzenediazonium hexafluorophosphate. The resulting solution was used to coat paper. The coated paper was placed on a conveyor moving at 270 feet per minute and passed beneath ~0413~9~3 , two 1200-watt mercury arcs, each 18 inches long. After ex-posure, the coating had cured to a hard, glossy finish.~
~ .
- P,Y~L~ 2 4 Eight difierent light-sensitive coating compo-sitions were prepared, each consisting of the following in-gredients in the indicated proportions by weight:
Prepolymer consisting sub- 30 parts stantially of diglycid~
yl ether of bisphenol A
; 10 1,4-Butanediol diglycidyl 3 parts 33 parts (66.0%) (3,4-Epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxylate 15 parts (30.0%) Monoepoxide (speciEied 2 pa~ts (4.0%) below) 50 parts (100.0%) j 2,5-Diethoxy-4-(p-tolylthio~- 0.5 parts (0.99%) of benzenediazonium hexafluoro- the total weight phosphate Each composition was mixed until the diazonium complex salt was distributed and dissolved therein. The bis-phenol A diglycidyl ether product was the same product as used in the composition of Example 23.
The monoepoxides used individually in the eight compositions, each monoepoxide product having a viscosity at 23C of less than 20 cps, were the followlng:
A-1,2~Epoxybutane B-Cyclopentene oxide (6-oxabicyclo~3.1.0~hexane) C-Cyclohexene oxide (7-oxabicycloa4.1.03heptane) D-Butyl glycidyl ether E-Phenyl glycidyl ether F-Tetrahydrofuran, CH CH GH CH -0 G-~xture of l-alke ~ edominantly 11 to 14 carbon atoms H-Mixture of l-alkenes having predominantly lS to 18 carbon atoms A portion of each of these eight compositions was spread in a thin film over paper, then placed on a conveyor moving at a speed ofi380 feet per minute beneath two 1200-watt -37_ \

mercury arc lamps at a distance of 2 inches from the coated surfaces of the paper. During passage under the mercury arcs all of the coatings cured to a hard, glossy finish.

l The following materials were mixed in the indicated ¦ proportions by weight:
.; Prepolymer consisting substan- 20 parts (60.6%) ~ tially of diglycidyl ether '~ of bisphenol A (as used in . 10 Example 23) ' '1 ' (3,4-Epoxycyclohexyl)methyl 10 parts (30.3~) .~ 3,4-epoxycyclohexanecarboxylate '-~ Alkyl glycidyl ether in 3 parts (9.1%) ~ which alkyl groups are . predominantly dodecyl and tetradecyl 33 parts (100.0%) ., p-Chlorobenzenediazonium 0.33 parts (0.97% of `l ' the total weight) .~ hexafluorophosphate .~ 10~ solution of poly(l-vinyl- 0.66 parts (1.94~ of , 20 the total weicJht) ..
2-pyrrolidinone) in propyl-ene carbonate . The poly(l-vinyl-2-pyrrolidinone) solution provided 0.19% of the total weight of that polymer dissolved in propylene carbonate, a nonvolatile solvent making up 1.75~ of the total weight. The poly(l-vinyl-2-pyrrolidinone,) had an average molecular weight of approximately 40,000. The beneficial effect of such small proportion of a polymerized l-vinyl-2-pyrrolidinone in inhibiting premature gelation of pol.ymerizable epo~ide composi-tions is disclosed and claimed in my Canadian application Serlal ,.
No. 166,412 filed March 19, 1973 entitled Controlled Polymeriza-. tion Process and Stabilized Polymerizable Compositions and assigned to the same assignee as that o.E the present invention.

~ - 38 -The yiscosity of the composition when freshly formulated as indicated in the preceding tabula-tion was about 500 cps at 23C.
.~

`t ' .~

- 38a -,: ' ' ~. , ~04819l~3 ' This composition was applied to the surface of paper on a web-fed gravure coater, and the coating was cured by passage under four 1,200-watt mercury arcs at a speed of 1,200 feet per minute to provide a hard, non-tacky finish.

An epoxide for~ulation suitable for appli-cation as a varnish to substrate surface is fonmulate by mixing the following materials:

Epoxy phenol novolak 850 g (68.0%) (3,4-Epoxycyclohexyl)methyl 280 g (22.4%) 3,4-epoxycyclohexanecarboxylate Alkyl glycidyl ether in 120 g (9.6%) which alkyl groups are predominantly dodeclyl and tetradecyl 1,250 g (100.0% of the blend~

95.85% of the total weight Silicone surfactant 6 g (0O45%) Mineral oil (liquid petrolatum) 10 g (0.8%) ~266 g p-Chlorobenzenediazonium12.66 g (0.97%) hexafluorophosphate Pol~ vinyl-2-pyrrolidinone)3.62 g (0.28%) Propylene carbonate _21.72 g ~
1,304.00 g (100.00%) The epoxidized novolak used in the above for-mulation was a product specified to maintain a viscosity at 52C within the range of 1,400 to 2~000~cps and an epoxy equivalent weight between 172 and 179. The viscosity of the mixture of three epoxides listed first hereina~ove closely approximated 2~500 cps at 23 C, which decreased to .
, .. .. .

lU48~1L98 1 29455 cps upon addition of the sillcone. The last-mentloned three components listed above were provided by addlng 38 g Or a solution formed by dissolvlng 20 g of the polyvinyl-pyrrolidinone and 70 g of the arenediazonium complex salt ln 100 ml (120 g) of propylene carbonate; alternatively, to obtaln the same compositlon, there could be added separately, to the 1,266 g of epoxide blendg 1% by weigh-t of the solld diazonlum salt catalyst and 2~ by weigh~ Or ~ 14.3~ solutlon of polyvlnylpyrrolidinone in propylene carbonate.
i~ The varnish as described above was applied on a 60-inch Miehle dry of~set sheet-fed press to coat paper sheets of 39 inch by 60 inch size at a rate of 5,000 ~m-pressions per hour. The coating thus provided on the sheets - was cured to a non tacky finlsh by passing the sheets at press speed beneath h'~h pressure nerc~ry arcs.
It was noted hereinaboveg with reference to Example 1, that the epoxide blend there described, consisting of ~ polyglycid~Jl ether of a polyhydric alcohol and a bis(ep-oxycycloal~yl) ester, is particularl~ useful for coating or ; printin~ on the sur~aces o~ metal substrates. Example 2 illustrates a simllar compositlon. It appears further from Ex~lpl~s 3, 4, 16, and 17 that the epoxidlc prepolymer material in such metal coating composltlons advantageously may be selected from the group conslsting not only of such ~ poly~lycldyl ether o~ a polyhydrlc alcohol, but also o~ a dlepoxlde of a cycloalkyl or alkylcycloalkyl hydroc~r~on or ether.
- Re~errin~ again to Example 25~ coated or prlnted matter is app~ied on A gravure pre~s to at least _l~o-''~''~ 7~ ' ` -1~48~98 predetermined areas of the surface of a paper substrate, for example to form a continuous glossy coating on the resulting paper product. For gra w re printing or decoration, it may be desired to modify the formulation appropriately, in a manner suggested hereinabove, by inclusion therein of some pigment and preferably somewhat higher proportion of the - less viscous epoxide materials.
` Referring further to Example 26, the epoxide polymer is coated or imprinted on a substrate by applying a portion of the polymerizable mixture on a dry offset press to at least predetermined areas of the surface of the sub-strate, followed by irradiation. In such a press the poly-merizable composition passes from a fountain down a train of distribution rollers for transfer to a roller having a solid raised surface (for coating) or raised image areas (for printing), followed by transfer to a rubber offset roller, from which the composition is deposied onto the substrate.
As mentioned above, the composition may be applied by this means to a paper substrate to produce a coated or imptrinted paper product. The same fiormulation is utiliæed alternatively, to produce such a paper product, by applying`a portion of the formulation, ~i~h~30r ~ithout added pigment, on letterpress apparatus directly to at least predetermined areas of the surface of a paper substrate.

~41-~4~
With reference to the coating or printing process using a dry offset press, and also to the above-described process for coating or printing on a paper sub-strate whether on a dry ofEset press or on letterpress apparatus or a gravure press, it has been found to be preferable to utilize, as the prepolymer resin material~ primarily pre-polymers of the type of the diglycidyl ether of bisphenol A
and the epoxidized novolaks. Epoxide blends utilizing these prepolymer resins are illustrated in a number of the examples set forth hereinaboveO When the epoxide materials also include a polyglycidyl ether of a polhydric alcohol, or a diepoxide of a cycloalkyl hydrocarbon or ether, the sum of the weights of such~polyglyc~dyl~ethér or cycloalkyl diepoxide present should not exceed about 10% of the total weight of the pre~
polymer material present. Compositions of the latter type are illustrated in the above Examples 19-24.
~hile there have been described particular embodiments of the inventionJ including those at present considered to be the preferred embodiments, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, to cover in the appended claims all such changes and modifications as fall within the true spirit and scope of the invention.

, '', . . : , ~ :.,

Claims (33)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A polymerizable composition, fluid at room tempera-ture and essentially free of volatile solvents consisting essentially of:
at least one epoxidic propolymer material having an epoxy equivalent weight below 200, constituting between 10% and 85% of the weight of the epoxidic materials in the composition, and selected from the group consisting of (A) an epoxy resin prepolymer consisting predominantly of the monomeric diglycidyl ether of bisphenol A, (B) a polyepoxidized phenol novolak or cresol novolak, (C) a polyglycidyl ether of a polyhydric alcohol, and (D) a diepoxide of a cycloalkyl or alkylcycloalkyl hydrocarbon or ether;
an epoxidic ester having two epoxycycloalkyl groups, and constituting at least 15% of the weight of the epoxidic materials in the composition;
and a radiation sensitive catalyst precursor which decomposes upon application of energy to provide a Lewis acid effective to initiate polymerization of said epoxidic materials.

2. The composition of claim 1, in which said catalyst precursor as present therein constitutes between 0.1% and 5% of the weight of the composition.

3. The composition of claim 1, in which said catalyst precursor as present therein constitutes between 0.5% and 2%
of the weight of the composition.

4. The composition of claim 1, 2 or 3 in which said catalyst precursor is an aromatic diazonium salt of a complex halide.

5. The composition of claim 1, in which said radia-tion-sensitive catalyst precursor is an aromatic diazonium salt of a complex fluoride or chloride.

6. The composition of claim 1, in which said catalyst precursor is a radiation-sensitive catalyst precursor in the form of p-chlorobenzenediazonium hexafluorophosphate.

7. The composition of claim 1, in which said catalyst precursor is a radiation-sensitive catalyst precursor in the form of 2,5-diethoxy-4-(p-tolylthio) benzenediazonium hexafluoro-phosphate.

8. The composition of claim 1, in which said epoxidic prepolymer material is an epoxy resin prepolymer consisting sub-stantially of the monomeric diglycidyl ether of bisphenol A.

9. The composition of claim 1, in which said epoxidic prepolymer material consists of an epoxy resin prepolymer in the form substantially of the monomeric diglycidyl ether of bisphenol A.

10. The composition of claim 1, in which said epoxidic prepolymer material is a polyepoxidized phenol novolak or cresol novolak.

11. The composition of claim 1, in which said epoxidic prepolymer material consists of a polyglycidyl ether of a poly-hydric alcohol.

12. The composition of claim 1, in which said epoxidic prepolymer material consists of a diepoxide of a cycloalkyl or alkylcycloalkyl hydrocarbon or ether.

13. The composition of claim 1, in which said ester having two epoxycycloalkyl groups is (3,4-epoxycyelohexyl) methyl 3,4-epoxycyclohexanecarboxylate.

14. The composition of claim 1, in which said ester having two epoxyeyeloalkyl groups is bis [(3,4-epoxy-6-methyl-cyclohexyl)methyl] adipate.

15. The process of producing an epoxide polymer, eomprising:

forming a mixture, fluid at room temperature and essentially free of volatile solvents, consisting essentially of (1) at least one epoxidic prepolymer material having an epoxy equivalent weight below 200, constituting between 10%
and 85% of the weight of the epoxidic materials in the mixture, and selected from the group consisting of (A) an epoxy resin prepolymer consisting predominant-ly of the monomeric diglycidyl ether of bisphenol A, (B) a polyepoxidized phenol novolak or cresol novolak, (C) a polyglycidyl ether of a polyhydric alcohol, and (D) a diepoxide of a cycloalkyl or alkylcycloalkyl hydrocarbon or ether, (2) an epoxidic ester having two epoxycycloakyl groups and constituting at least 15% of the weight of the epoxidic materials in the mixture, and (3) a radiation sensitive catalyst precursor which decomposes upon application of energy to provide a Lewis acid effective to initiate polymerization of said epoxidic materials, said catalyst precursor is an aromatic diazonium salt of a com-plex halide;
applying a portion of the mixture so formed to a sub-strate;
and subsequently applying energy to said mixture on the substrate to activate said initiator and effect substantial poly-merization of said epoxidic materials.

16. The process of claim 15 for producing an epoxide polymer, in which said catalyst precursor as present upon forming said mixture constitutes between 0.1% and 5% of the weight of the mixture.

17. The process of claim 15 for producing an epoxide polymer, in which said catalyst precursor as mixed with said epoxidic materials constitutes between 0.5% and 2% of the weight of the resulting mixture.

18. The process of claim 15, 16 or 17 in which said catalyst precursor is an aromatic diazonium salt of a com-plex halide.

19. The process of claim 15, in which said catalyst precursor is 2,5-diethoxy-4-(p-tolylthio)benzenedia zonium hexa-fluorophosphate.

20. The process of claim 15, wherein said applied energy is actinic radiation.

21. The process of producing an epoxide polymer com-prising:
forming a mixture, fluid at room temperature and essentially free of volatile solvents, consisting essentially of (1) at least one epoxidic prepolymer material having an epoxy equivalent weight below 200, constituting between 10%
and 85% of the weight of the epoxidic materials in the mixture, and selected from the group consisting of (A) an epoxy resin prepolymer consisting predominant-ly of the monomeric diglycidyl ether of bisphenol A, (B) a polyepoxidized phenol novolak or cresol novolak, (C) a polyglycidyl ether of a polyhydric alcohol, and (D) a diepoxide of a cycloalkyl or alkylcycloalkyl hydrocarbon or ether, (2) an epoxidic ester having two epoxycycloalkyl groups and consisting at least 15% of the weight of the epoxidic materials in the mixture, (3) a monoepoxide having a viscosity at 23°C of less than 20 centipoises and constituting up to 15% of the weight of the epoxidic materials in the mixture, and (4) a radiation sensitive catalyst precursor which decomposes upon application of energy to provide a Lewis acid effective to initiate polymerization of said epoxidic material, said catalyst precursor is an aromatic diazonium salt of a complex halide;
applying a portion of the mixture so formed to a sub-strate;
and subsequently applying energy to said mixture on the substrate to activate said catalyst precursor and effect sub-stantial polymerization of said epoxidic materials.

22. The process as claimed in claim 21 in which said catalyst precursor is an aromatic diazonium salt of a complex halide.

23. The process of claim 22, wherein said applied energy is actinic radiation.

24. The process of claim 22, for producing an epoxide polymer, in which the catalyst precursor as present upon forming said mixture constitutes between 0.1% and 5% of the weight of the mixture.

25. The process of claim 22, in which said catalyst precursor as mixed with said epoxidic materials constitutes between 0.5% and 2% of the weight of the resulting mixture.

26. The process of claim 22, for producing an epoxide polymer, in which the catalyst precursor in said mixture is a radiation-sensitive catalyst precursor in the form of 2,5-dieth-oxy-4-(p-tolylthio)benzenediazonium hexafluorophosphate.

27. The process of claim 22, for producing an epoxide polymer, in which the epoxidic prepolymer material in said mix-ture is an epoxy resin prepolymer consisting substantially of the monomeric diglycidyl ether of bisphenol A.

28. The process of claim 27, in which the epoxidic prepolymer material in said mixture consists of an epoxy resin prepolymer in the form substantially of the monomeric diglycidyl ether of bisphenol A.

29. The process of claim 22, for producing an epoxide polymer, in which the epoxidic prepolymer material in said mix-ture is a polyepoxidized phenol novolak or cresol novolak.

30. The process of claim 22, in which the epoxidic prepolymer material in said mixture consists of a polyglycidyl ether of a polyhydric alcohol.

31. The process of claim 22, in which the epoxidic prepolymer material in said mixture consists of a diepoxide of a cycloalkyl or alkylcycloalkyl hydrocarbon or ether.

32. The process of claim 22, for producing an epoxide polymer, in which said ester having two epoxycycloalkyl groups in said mixture is [(3,4-epoxycyclohexyl)methyl 3,4-epoxycyclo-hexanecarboxylate.

33. The process of claim 22, for producing an epoxide polymer, in which said ester having two epoxycycloalkyl groups in said mixture is bis[(3,4-epoxy-6-methylcyclohexyl)methyl]
adipate.