Patent GB-906427-A (GB)
Title: Improvements in or relating to the polymerisation of polyesters
IPC: C08G63/52
Filed: 1959-01-05
Abstract: Multi-component hard copolymer resins are obtained by copolymerizing (A) an unsaturated non-linear polyester of molecular weight between 800 and 3,000 and an acid number not above 12, produced in several stages from mono- and poly-hydric alcohols and a mixture of mono- and poly-basic carboxylic acids comprising aromatic and olefinically unsaturated acids; (B) an unsaturated, non-linear, multi-branched polyester of molecular weight between 400 and 1,500; and (C) a mixture of several copolymerizable monomers consisting mainly of hydrocarbons with minor proportions of esters, each comprising aromatic and unsaturated aliphatic components.  Hardening copolymerization of the liquid mixtures may be effected in the presence of organic peroxides (e.g. MEK peroxide) which act as initiators, of a solution of a metal compound and/or an amino compound which acts as an accelerator, of a plasticizer, and of an inhibitor, e.g. a phenol, a quinone or a copper salt.  Fillers and/or structural or carrier materials may also be present.  Specified constituents of monomer mixture (C) are:- (i) as hydrocarbons, vinyl aromatic compounds, e.g. styrene, vinyl toluene, ethyl styrene, divinyl benzene, vinyl carbazole, and substituent products thereof carrying alkyl or aryl radicals or halogen, ether or ester groups and (ii) as esters, esters of phenols comprising unsaturated aliphatic components, esters of benzyl alcohol or p dihydroxyethyl benzene with acrylic, methacrylic or crotonic acid, and esters of unsaturated alcohols with aromatic carboxylic acids, e.g. the allyl esters of a mixture of benzoic, o- and isophthalic, and pyromellitic acids, which are used in the examples in admixture with styrene, ethyl styrene and divinyl toluene.  Preparation of polyesters A and B. Polyester A is synthesized from mixtures of mono- and polybasic acids and mono- and polyhydric alcohols in several stages by preliminary and after-esterification using amines or amino-alcohols to catalyze the latter, e.g. esters of different degrees of saturation having terminal acid groups may be first produced and then linked and neutralized by after-esterification. In examples (A1) the initial charge consists of ethylene glycol, diglycol, maleic and phthalic anhydrides and benzoic and citric acids.  In the second stage, conducted in boiling xylene and using stearyl amine as catalyst a mixture of hexanetriol, 1-methyl-1,3-propylene glycol and n-hexanol is added in 5 portions; (A2) the initial charge is phthalic anhydride, benzoic and citric acids, ethylene glycol and diglycol, in an intermediate stage fumaric acid is introduced, and the final stage is as in A1 except that the methyl propylene glycol is replaced by glycol.  Polyester B is preferably synthesized in stages by first reacting an at least trihydric hydroxy compound with unsaturated dicarboxylic acids and then neutralizing with mono- or polyhydric alcohols.  Exemplified at least trihydroxy compounds are hexanetriol, trimethylol propane, pentaerythritol, trimethylol ethane, triethanolamine, mannitol and sorbitol.  In examples:- (B1) pentaerythritol and maleic anhydride are esterified and neutralized portion-wise with butanol in the presence of p-toluene sulphonic acid and benzene; (B2) first butanol and finally glycol are used for the neutralization; (B3) pentaerythritol, pentaerythritol distearate, hexanetriol and maleic anhydride are esterified and neutralized successively with butanol, glycol and finally more butanol.