GB991452A - The production of epoxide resins - Google Patents

Abstract

Ester-group-containing mono-, di- or polyepoxides in which the ester groups are disposed upon an alicyclic system are prepared either by the reaction of a hydroxyl-containing cyclo-aliphatic epoxide with an ester of a mono-, di- or poly-carboxylic acid or an ester of an epoxide-containing cycloaliphatic carboxylic acid with a di- or poly-hydric-alcohol in the presence of a known transesterification catalyst not having a strongly acidic reaction. Preferred epoxy alcohols include those of the formula <FORM:0991452/C2/1> where A and B may each be hydrogen or a methyl group and n is any integer from 0 to 10, prepared by the methods disclosed in Specification 943,925 or 991,453; specified members of this class are the two stereoisomers of epoxydihydrodicyclopentadienol and the ethylene glycol derivative where n = 1 and A = B = H. Other suitable epoxy alcohols are those of the formulae <FORM:0991452/C2/2> and <FORM:0991452/C2/3> where R3-9 may be hydrogen or simple alkyl groups and where R1 and R2 may be hydrogen or, as may R3 and R8, together form a methylene group, e.g. 3,4-epoxy-2,5-endomethylenecyclohexanol, 3,4-epoxy-cyclohexanol, 1-hydroxymethyl-3,4-epoxydychlohexane and 1-hydroxymethyl - 6 - methyl - 3,4 - epoxy - 2,5 - endomethylenecyclohexane. 2,3 - epoxycyclopentanol is also named. The specified mono-, di- and polybasic acids whose esters are suitable for transesterification with epoxy alcohols include sorbic, acrylic, a -chloroacrylic, piperic, acetic, benzoic, oxalic, succinic, stearic, phthalic, maleic, itaconic, citric and trimellitic acids and dimerized long chain fatty acids. In the alternative process employing an epoxide-containing ester and di- or poly-hydric alcohol the preferred class of esters are those of the general formula <FORM:0991452/C2/4> where R10, R11, R13-17 may each be hydroge or an alkyl group, R10 and R16 may together form a methylene bridge and R12 represents an alkyl group. A further specified class are those esters of epoxy-carboxylic acids obtained by transesterification of an alicyclic epoxy-alcohol with a di- or polycarboxylic acid using less alcohol than is required to react with every ester group, e.g. the 3-ethoxy-propionates of the above epoxy-dihydrodicyclopentadienols. Suitable di- or poly-hydric alcohols include ethylene glycol, diethylene glycol, higher polyethylene and polypropylene glycols, butane diols, xylylene glycols, glycerol, penta-erythritol, isosorbide, sorbitol and sucrose. The hydroxyl functions may be replaced by primary or secondary amine or thiol functions, e.g. thioethylene glycol, ethanolamine or triethanolamine. The transesterification catalyst is preferably a basic compound such as an alkoxide, hydride or alkyl derivative of a metal of Group Ia, IIa or IVb or a carboxylate of Group IIb or IVa; these may be added as such or formed in situ. Other specified catalysts include quaternary ammonium hydroxide or ion-exchange resins containing them or organometallics such as dibutyl tin oxide or tetrabutyl titanate. The reaction can be effected in a melt or in an inert solvent and preferably in the temperature range 20-180 DEG C., if required, the displaced alcohol being removed as the reaction proceeds. Generally the reactants are employed in stoichrometric ratio. The di-and poly-epoxy esters can be treated with conventional hardeners for epoxy resins to give compositions especially useful as electrical insulators (see Division C3). Numerous examples describe the preparation of the epoxy esters and hardenable compositions thereof. Specifications 938,809, 943,924, 977,712, 987,927 and 991,451 are referred to.ALSO:Epoxy resins are produced from ester-group-containing di- or poly-epoxides in which the epoxide groups are disposed upon an alicyclic system and which are prepared by either the reaction of a hydroxyl-containing cycloaliphatic epoxide with an ester of a mono-, di- or polycarboxylic acid or the reaction of an ester of an -epoxide containing cycloaliphatic carboxylic acid with a di- or polyhydric alcohol in the presence of a known transesterification catalyst not having a strongly acid reaction. The polymers are prepared by the reaction of the epoxyester with known hardeners, e.g. polyhydric phenols, reaction products of aluminium alkoxides or phenolates with tautomeric compounds of the aceto-acetic acid type, F-C catalysts or tri-B-alkyl, -aryl; -alkoxy borozines; the preferred hardeners are the polybasic acids and their anydrides. Suitable accelerators such as tertiary amines may also be used. The hardenable compositions can also contain more than one epoxy-ester, or a proportion of said ester in which some or all of the epoxide groups are hydrolysed and/or additional polyhydroxy compounds. Other epoxides may also be present, e.g. mono- or poly-glycidyl ethers of mono- or poly-alcohols or phenols, epoxidized polyolefinic compounds such as unsaturated fatty acid esters, epoxidized butadiene polymers, polyglycidyl esters of polycarboxylic acids or amino-polyepoxides. The compositions may include fillers, plasticizers or colouring agents and can be used in the filled or unfilled state as, e.g., textile auxiliaries, varnishes or coating materials. Examples XLIX -LV describe the preparation of resins from various epoxy-esters using as hardening agents phthalic anhydride, with or without the addition of benzyldimethylamine and methylendomethylenetetrahydrophthalic anhydride and benzyldimethylamine. In Example LIV a mixture of an epoxy-ester and styrene is treated with methylendomethylenetetrahydrophthalic anhydride, benzoyl peroxide and benzyldimethylamine. Data on the heat deflection temperature, flexural strength, impact strength and dielectric constant of some of these compositions is given. Specifications 938,809, 943,924, 943,925, 977,712, 987,927, 991,451 and 991,453 are referred to.