Patent GB-965550-A (GB)
Title: Epoxy resin polyester compositions
IPC: C09D5/25
Filed: 1960-08-18
Abstract: A curable electrically insulating resin comprises a blend of (1) a branched-chain acid terminated polyester of at least one dicarboxylic acid, at least one dihydric alcohol and a polyfunctional alcohol with at least three non-tertiary hydroxyl groups or a polyboric acid with at least three carboxyl groups, not more than 50 mol. per cent. of the total of acids and alcohols containing aromatic rings, which polyester contains 2.1 to 3.0 carboxyl groups per molecule, has an acid number of 15 to 125, a hydroxyl number of less than 10 and is free from ethylenic unsaturation, and (2) a compound containing on average at least 1.3 oxirane or aziridine groups and at least one oxirane group per molecule, and when there are two or more of said groups in a molecule they are separated by a chain of at least two carbon atoms and free from ethylenic unsaturation.  Polyesters specified as useful are prepared from:-A. isophthalic acid, "isosebacic" acid, propylene glycol, glycerol, and triphenyl phosphite as a catalyst.  B. adipic acid, isophthalic acid, propylene glycol, 1,1,1-trimethylol propane, and triphenyl phosphite as catalyst.  C. "isosebacic" acid, propylene glycol, trimethylol propane and triphenyl phosphite as catalyst. D. "isosebacic" acid, neopentyl glycol, trimethylol-propane and p-toluene sulphonic acid as catalyst.  E. adipic acid, isophthalic acid, propylene glycol, trimethylol-propane and triphenyl phosphite as catalyst.  F. "isosebacic" acid, isophthalic acid, propylene glycol, trimethylolpropane and triphenyl phosphite as catalyst.  Other suitable ingredients for the polyesters are o-phthalic acid, azelaic acid, chlorendic anhydride, 1, 4-butane diol, ethylene glycol, 2,2-bis[4-(2 - hydroxypropoxy) - phenyl] propane, pentaerythritol, trimeric acid, citric acid, trimellitic acid, benzene tetracarboxylic acid, and tricarballylic acid.  Suitable epoxy compounds are:-diglycidyl ethers of resorcinol or bisphenol A, a condensate of epichlorhydrin and 1,1,2,2-tetrakis (4 hydroxyphenyl)-ethane, limonene dioxide, dicyclopentadiene-2, 3, 5, 6-dioxide, 1-epoxy-3, 4-epoxy cyclohexane, 3, 4-epoxy-6-methylcyclohexylmethyl-3, 4-epoxy-6-methylcyclohexanecarboxylate, and epoxidized novolacs.  The compositions may include cross-linking agents for epoxy resins, e.g. a polycarboxylic acid anhydride, a catalyst for the reaction between the epoxy compound and the polyester, e.g. a tertiary amine or salt thereof, and mono-epoxides, e.g. 1-epoxydodecane, 2, 3-epoxy octane, dipentene-1,2-monoxide, a -pinene oxide, styrene oxide, phenyl glycidyl ether, 1, 2-epoxy-4-vinylcyclohexane and epoxidized olefinies.  Examples describe specific combinations of one of the specified polyesters with a solid or liquid condensate of epichlorhydrin and bisphenol A.  Example 10 uses N-(2, 3-epoxy-propyl)-2-ethylaziridine as the epoxy compound.  Examples 1 to 5, 8, use tris (2, 4, 6-dimethylaminomethyl)-phenol as catalyst, and Example 9 uses diethylenetriamine.  The compositions may be used e.g. as a solution in toluene to form films, to impregnate a web of polyethylene terephthalate fibres of glass fibres, or of mica platelets, to make castings, or to coat copper wire.  In Example 8 one composition included iron oxide red pigment, and another iron oxide and silica powder.  It is also stated that crepe paper may be impregnated with the compositions of the invention to form electrical insulation.