Description HEAT CURABLE COMPOSITIONS Cross Reference. to Related Applications RD-11473, for Curable Organic Resin Compositions, Foam- Method and Organic Fo ms, filed concurrently herewith, RD-11424, filed on or about November 20, 1978, for Curable Organic Resin Compositions and Foaming Method, which is a continuation-in-part of Serial No. 861,127, filed December 16, 1977, for Curable Organic Resin Compositions and Foaming Method, now abandoned, copending application Serial No. 861,128, for Heat Curable Compositions, filed December 16, 1977, which is a continuation- in-part application of Serial No. 781,785, filed March 28, 1977, for Heat Curable Epoxy Compositions and Method for Curing Same, now abandoned, copending application Serial No. 940,564, filed Sept. 8, 1978 for Heat Curable Compositions and Method of Cur¬ ing Same which is a continuation-in-part of copending applica¬ tion Serial No. 841,351, filed October 12, 1977, for Heat Cur- able Compositions, which is a continuation-in-part of Serial No. 689,247, filed May 24, 1976, fo ^" r Epoxy Compositions and Method of Curing Same, now abandoned, where all of the aforesaid appli¬ cations are assigned to the same assignee as the present inven¬ tion. Background of the Invention

The present invention relates to heat curable compos¬ itions comprising a cationically polymerizable organic material, for example, an epσxy resin, a dialkyl hydroxyarylsulfonium salt and an organic oxidant. As shown in m ,copending application Serial No.

940,564, for Heat Curable Compositions and Method for Curing Same, filed September 8, 1978 and assigned to the same assignee as the present invention, organic resins, for example, epoxy

resins can be thermally cured by using an effective amount of an aromatic onium salt such as an aryl iodonium salt and a reducing agent, for example, a thiophenol. The present inven¬ tion is based on £he discovery that such organic resin also can be thermally cured with an organic oxidant, such as an organic peroxide in combination with an effective amount of certain hydroxyaryldialkyl sulfonium salts, for example,

OH

dimethyl-4-hydroxy-3,5-dimethylphenyl sulfonium hexafluoro- arsenate.

Statement of the Invention There is provided by the present invention, heat curable compositions comprising

(A) a cationically polymerizable organic material, (B) an effective amount of a thermal curing agent consisting essentially of an organic oxidant and a dialkyl hydroxy aryl sulfonium salt.

Included by the dialkylhydroxyarylsulfonium salts which can be used in the practice of the present invention are compounds having the formula,

(1) [R (R ¹ ) _a S] [Y] , where R is a C ₍ e _t _20' ^aromat i ^c radical having from 1 to 3 nuclearly bonded hydroxy radicals, R can be the same or differ¬ ent Cr-,_gv alkyl radical or an alkylene radical capable of form- ing a cycloaliphatic or heterocyclic ring, Y is a non-nucleo-

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philic anion, a is an integer equal to 1 or 2, and when R is alkyl, a is 2, and when R is alkylene, a is 1.

Radicals included by R of formula (1) are, for example,

R radicals include CH ₃ -,-C^H _g -, C^-, CH ₃ 0-, (CH ₃ ) ₃ C-

CZ-HCCHΛ-, -CH2-CHΛ-O-CH -CH2-,

-CH ₂ -CH ₂ -S--CCHH ₂₂ --CCHH ₂₂ --, eettcc. Preferably, the salts, included by formula (1) , are

where R 1, M, Q and d are as previously defined, and R2-R6 are onovalent radicals selected from hydrogen, •~ ₍ - _ _o - alkyl,

C _JV ^' alkoxy, nitro, chloro, etc.

Dialkyl hydro yphenylsulfonium salts included by formulas (1) and (2) are,

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^* ? ^* ^

Methods for making some of the dialkyl hydroxy aryl sulfonium salts of formulas (1) and (2) are shown in U.S. patents 4,058,400 and 4,058,401, and in my copending applica- tions Serial Number 833,146, filed September 14, 1977 and Serial Number 954,196, filed October 24, 1978.

Organic oxidants which can be used in the practice of the invention incombination with the dialkylhydroxy arylsul- fonium salts of formulas 1 and 2 to effect the cure of the cat- ionically polymerizable organic material are, for example,organic peroxides such as ketone peroxides,peroxy acids, dibasic acid peroxides, aldehyde peroxides, alkyl peroxides, hydroperoxides, alkyl peroxyesters, diperoxide derivatives, for example, t-butyl peroxypivalate, 2,4-dichlorobenzoyl peroxide, caprylyl peroxide, lauroyl peroxide, decanoyl peroxide, propionyl per¬ oxide, acetyl peroxide, t-butyl peroxyisobutyrate, p-chloro- benzoyl peroxide, benzoyl peroxide, hydroxyheptyl peroxide, cyclohexanone peroxides, 275-dimethylhexyl-2,5-di(peroxybenzo- ate) , di-t-butyl diperphthalate, t-butyl peracetate, t-butyl-

- ^■ REA

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perbenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butyl- peroxy)hexane, t-butyl hydroperoxide, di-t-butyl peroxide, methyl ethyl ketone peroxide, p-methane hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexyl-2,5-dihydroperoxide, t-butyl hydroperoxide, peracetic acid, perbenzoic acid, m-chloroper- benzoic acid, etc.

In addition to organic peroxides, organic oxidants which also can be used in the practice of the invention include azo-bis alkyl nitriles and other azo zompounds, such as

CH, CH,

(C ₆ H ₅ ) ₃ C-N=N-C(C ₆ H ₅ ) ₃ CH ₃ -C-N=N-C-CH ₃

CH. CN

CH, CH,

^~ 3 , 3 C ₂ H ₅ -C-N=N-C-C ₂ H ₅ etc.

CN - CN

quinones , such as

iodoso aromatic compounds, such as iodosobenzene, 4-nitroiodoso- benzene, iodosobenzene diacetate, 4,chloroiodosobenzene, 4-meth- oxyiodosobenzene, 4-iodosobiphenyl, 2-chloroiodosobenzene di¬ acetate, etc. Cationically polymerizable organic materials which can be used to make the heat curable compositions of the present invention include epoxy resins, thermosetting organic condensation resins of formaldehyde, vinyl organic prepolymers, cyclic ethers, etc. The term "epoxy resin" as utilized in the descrip¬ tion of the cationically polymerizable compositions of the present invention, includes any monomeric, dimeric or oligo- meric or polymeric epoxy material containing one or a plural¬ ity of epoxy functional groups. For example, those resins which result from the reaction of bisphenol-A (4,4 ^* -isopro- pylidenediphenol) and epichlorohydrin, or by the reaction-of low molecular weight phenol formaldehyde resin (Novolak resin) with epichlorohydrin, can be used alone or in combination with an epoxy containing compound as a reactive diluent. Such diluents as phenyl glycidyl ether, 4-vinylcyclohexene dioxide, limonene dioxide, 1,2-cyclohexene oxide, glycidyl acrylate, glycidyl methacrylate, styrene oxide, allyl glycidyl ether, - etc., may be added as viscosity modifying agents.

In addition, the range of these compounds can be extended to include polymeric materials containing terminal or pendant epoxy groups. Examples of these compounds are vinyl copolymers containing glycidyl acrylate or methacrylate as one of the comonomers. Other classes of epoxy containing polymers amenable to cure using the above catalysts are epoxy-

siloxane resins, epoxy-polyurethanes and epoxy-polyesters. Such polymers usually have epoxy functional groups at the ends of their chains. Epoxy-siloxane resins and method for making are more particularly shown by E. P. Plueddemann and G. Fanger, J. Am. Chem. S _. oc. 8_02632-5 (1959). As described in the lit¬ erature, epoxy resins can also be modified in a number of standard ways such as reaction with amines, carboxylic acids, thiols, phenols, alcohols, etc., as shown in patent 2,935,488; 3,235,620; 3,369,055, 3,379,653; 3,398,211, 3,403,199; 3,563,840; 3,567,797; 3,677,995; etc. Further coreactants which can be used with epoxy resins are hydroxy terminated flexibilizers such as hydroxyl terminated polyethers, hydroxy terminated polyesters, etc., shown in the Encyclopedia of Polymer Science and Technology, Vol. 6, 1967, Interscience Publishers, New York, pp. 209-271 and particularly p. 238.

Included by the thermosetting organic condensation resins of formaldehyde which can be used in the practice of the present invention are, for example, urea type resins, such as

[CH ₂ =N-C0NH ₂ ] _χ .H ₂ 0 [CH ₂ =NC0NH ₂ ] _χ CH ₃ C00H

[CH ₂ =NC0NHCH ₂ NHC0NHCH ₂ 0H] ₂ phenol-formaldehyde type resin, such as

where x and n are integers having a value of 1 or greater;

alkoxy silanes having the formula,

(R ⁷ 0) _m Si (R ⁸ ) _n ,

7 8 7 where R is a C _f1 _ ₇ ^ alkyl radical, R is selected from R radicals and C,g_-, ₃ - ₎ aryl radicals and halogenated derivatives, m is an integer equal to 1 to 4, n is an integer equal to 0 to 3 inclusive and m + n is equal to 4.

In addition, there can be used melamine thiourea resins, melamine, or urea aldehyde resins, cresol-formaldehyde resins and combinations with other carboxy, hydroxyl, amino and mercapto containing resins, such as polyesters, alkyds and poly- sulfides.

Some of the vinyl organic prepolymers which can be used to make the polymerizable compositions of the present invention are, for example, CH ₂ =CH-0-(CH ₂ -CH ₂ 0) _n ,-CH=CH ₂ , where n' is a positive integer having a value up to about 1000 or higher; multi-functional vinylethers, such as 1,2,3-propane trivinylether, trimethylolpropane trivinylether, prepolymers having the formula,

CH=CH ₂ low molecular weight polybutadiene having a viscosity of from 200 to 10,000 centipoises at 25°C, etc. Products resulting from the cure of such compositions can be used as printing inks and other applications typical of thermosetting resins.

A further category of the organic materials which can be used to make the polymerizable compositions are cyclic ethers which are convertible to thermoplastics. Included by such cyclic ethers are, for example, oxetanes such as 3,3-bis- chloromethyloxetane, alkoxyoxetanes as shown by Schroeter Patent 3,673,216, assigned to the same assignee as the present invention; oxolanes such as tetrahydrofuran, oxepanes, oxygen containing spiro compounds, trioxane, dioxolane, etc.

In addition to cyclic ethers there are also included cyclic esters such as β-lactones, for example propiolactone, cyclic amines, such as 1,3,3-trimethyl-azetidine and organo- silicone cyclics, for example, materials inlcuded by the formula,

where R" can be the same or different monovalent organic radical

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such as methyl or phenyl and p is an integer equal to 3 to 8 inclusive. An example of an organosilicon cyclic is hexamethyl trisiloxane, octamethyl tetrasiloxane, etc. The products made in accordance with the present invention are high molecular weight oils and gums.

The heat curable compositions of the present inven¬ tion can be made by blending the cationically polymerizable organic material with an effective amount of the thermal cur¬ ing agent. There can be used 0.1 to 10 percent by weight of the dialkyl hydroxyarylsulfonium salt based on the weight of cationically polymerizable organic material. With respect to the combination of organic oxidant and dialkylhydroxyaryl- sulfonium salt, there can be used from 1 to 100 parts of organic oxidant, per part of dialkyl hydroxy arylsulfonium salt.

The resulting curable, composition can be in the form of a varnish having a viscosity of from 1 to 100,000 centipoises at 25°C or a free flowing powder, depending upon the nature of the cationically polymerizable organic material. The curable compositions can be applied to a variety of substrates by con¬ ventional means and cured to the tack-free state within 0.5 to 20 minutes, depending upon the temperature employed.

In certain instances, an organic solvent, such as nitromethane, acetonitrile, can be used to facilitate the mixing of various ingredients. The dialkyl hydroxy arylsulfon¬ ium salts can be formed in situ if desired. In addition, the curable compositions may contain inactive ingredients, such as silica, talc, clay, glass fibers, extenders, hydrated alumina, carbon fiber process aids, etc., in amounts of up to 500 parts of filler per 100 parts of cationically polymerizable organic

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material. The curable compositions can be applied to such substrates as metal; rubber, plastic, molded parts or films, paper, wood, glass, cloth, concrete, ceramic, etc.

Some of the applications in which the curable compos- itions of the present invention can be used are, for example, protective, decorative and insulating coatings, potting com¬ pounds, printing inks, sealants, adhesives, molding compounds, wire insulation, textile coatings, laminates, impregnated tapes, varnishes, etc. In order that those skilled in the art will be better able to practice the invention, the following examples are given by way of illustration and not by way of limitation. All parts are by weight. Example 1. A mixture of three parts of dimethyl-4-hydroxy-3,5- dimethoxyphenyl sulfonium hexafluoroarsenate, three parts of benzoylperoxide and 94 parts of Shell Epon 828, a diglycidyl ether of bisphenol-A, was stirred and heated to 160 ^β C. The mixture gelled and hardened within 2.5 minutes. Example 2.

The procedure of Example 1 was repeated, except that Celanese SU8, epoxy novolak resin was substituted for the diglycidyl ether bisphenol-A epoxy resin. The resuting heat curable composition required eight minutes to harden at 120°C. Example 3.

A series of mixtures were prepared utilizing 100 parts, of 3,4-epoxycyclohexylmethyl-3,4-epoxy cyclohexane carboxylate, 3 parts of a hexafluoroantimonate salt of the formula,

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and 3 parts of various organic oxidants. The mixtures were then heated to 130°C to determine gel times. The following results were obtained:

Organic oxidant Gel Time

None >7 min. benzoyl peroxide 1 min. , 30 sec. cumene hydroperoxide 2 min. , 50 sec.

2,3-dichloro-5,6-dicyano- 40 sec. quinone azo-bisisobutyronitrile 6 min. 15 sec. lauroyl peroxide 4 min. 5 sec. Example 4.

In accordance with the procedure of Example 3, heat curable mixtures were prepared ^" utilizing 100 parts of ERL 4221 (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxy- late) , 3 parts of

and 3 parts of various organic oxidants. The mixtures were heated to 150°C to determine when the mixtures changed from a fluid condition to the solid cured state. The following results were obtained:

Organic oxidant Gel Time

None 25 min. methylethyl ketone peroxide 11 min. t-butyl hydroperoxide 3 min.

Example 5. •

A mixture composed of 100 parts of 1,4-butanediol diglycidyl ether, 3 parts of t-butyl hydroperoxide and 3 parts of dimeth 1-3,5-dimethoxy-4-hydroxyphenylsulfonium hexafluoro- arsenate was heated at 150°C. The mixture cured to a hard crosslinked resin after 18 minutes. The same mixture free of the t-butyl hydroperoxide did not gel after it was heated for 60 minutes.at 140°C. Example 6.

Mixtures were prepared having 100 parts of diethyl- eneglycol divinyl ether and 3 parts of

There was added 3 parts of t-butyl hydroperoxide to one of the mixtures. Both mixtures were thoroughly stirred and then heated to 140°C The mixture containing the peroxide cured after 5 minutes, while the mixture free of peroxide required 15 minutes to cure to a tack-free condition. Example 7.

Mixtures of 100 parts of Methylon* resin (a phenol- formaldehyde resole of the General Electric Company) and 3 parts of

were thoroughly stirred. There was added 3 parts of t-butyl hydroperoxide to one of the mixtures . The mixtures were then heated at 150°C. The mixture having the t-butyl hydro- peroxide cured to a hard crosslinked insoluble resin. The mixture free of the organic oxidant remained substantially unchanged.

Although the above examples are directed to only a few of the very many heat curable compositions included by the present invention, it should be understood that the present invention includes a much broader class of heat cur¬ able material as shown by the description preceding these examples.