Patent GB-716033-A (GB)
Title: Improvements in and relating to methods of casting polyester type resins
Inventor: SNADOW RONALD
IPC: B29C39/00
Filed: 1951-08-20
Abstract: Liquid "polyester type resin" (see below) is poured into a mould made of polythene, heated in the mould to a temperature kept below 90 DEG C. until it hardens, and removed from the mould; its cure may be completed by heating it at 100-200 DEG C.  "Polyester type resin" is defined as a composition comprising (a) a polyhydric alcoholic polyester of an olefine alpha-beta dicarboxylic acid (in which part of the olefine alpha-beta dicarboxylic acid may be replaced by another dicarboxylic acid, e.g. phthalic or succinic acid) and (b) a miscible polymerizable monomer which contains the group CH2=C <; e.g. a mixture of polydiethylene glycol maleate and styrene.  A resinous polymer such as polyvinyl acetal may also be included.  In one example a composition comprising 1 part by weight of diethylene glycol maleate, 1 part of diallyl phthalate and 0.0025 part of benzoyl peroxide is cast in a cylindrical polythene mould into the form of a disc 1/8 th inch in section, the mould is heated in an oven at 80 DEG C. for 3 hours, a thin film of polythene being placed on the resin to inhibit surface cure, and the disc is then removed from the mould and heated for 1 hour at 100 DEG C. and 2 hours at 200 DEG C.  In another example the end windings of the stator of an electric induction motor are enclosed by fitting a polythene mould over them and casting around them a composition comprising (a) 45 parts by p weight of the reaction product of 46.3 parts of propylene glycol, 46.3 parts of succinic acid and 6.2 parts of maleic anhydride, (b) 55 parts of monomeric styrene, (c) 1 part of t-butyl perbenzoate and (d) 0.01 part of cobalt naphthenate (containing 6 per cent. of cobalt). After pouring, the resin is allowed to stand in the mould at room temperature for 3 hours, then heated in an oven at 80 DEG C. for 5 hours.  In a modification of this example, using 1-hydroxy-cyclohexyl hydroperoxide-1 as the catalyst and adding 20 parts of talc, the resin is allowed to harden in the mould for 16 hours at room temperature before removal from the mould. Specification 613,880 is referred to.ALSO:Liquid "polyester type resin" (see below) is poured into a mould made of polythene, heated in the mould to a temperature kept below 90 DEG  C. until it hardens, and removed from the mould; its cure may be completed by heating it at 100-200 DEG  C. "Polyester type resin" is defined as a composition comprising (a) a polyhydric alcoholic polyester of an olefine alpha-beta dicarboxylic acid (in which part of the olefine alpha-beta dicarboxylic acid may be replaced by another dicarboxylic acid, e.g. phthalic or succinic acid) and (b) a miscible polymerizable monomer which contains the group CH2=C<; e.g. a mixture of polydiethylene glycol maleate and styrene.  In one example a composition comprising 1 part by weight of diethylene glycol maleate, 1 part of diallyl phthalate and 0.0025 part of benzoyl peroxide is cast in a cylindrical polythene mould into the form of a disc 1/8 inch in section, the mould is heated in an oven at 80 DEG  C. for 3 hours, a thin film of polythene being placed on the resin to inhibit surface cure, and the disc is then removed from the mould and heated for 1 hour at 100 DEG  C. and 2 hours at 200 DEG C.  In another example the end windings of the stator of an electric induction motor are enclosed by fitting a polythene mould over them and casting around them a composition comprising (a) 45 parts by weight of the reaction product of 46.3 parts of propylene glycol, 46.3 parts of succinic acid and 6.2 parts of maleic anhydride, (b) 55 parts of monomeric Illegible data (c) 1 part of t-butyl perbenzoate and (d) Illegible data part of cobalt naph thenate (containing 6 per cent. of cobalt).  After pouring, the resin is allowed to stand in the mould at room temperature for 3 hours, then heated in an oven at 80 DEG C. for 5 hours.  In a modification of this example, using 1-hydroxy cyclohexyl hydroperoxide-1 as the catalyst and adding 20 parts of talc, the resin is allowed to harden in the mould for 16 hours at room tem perature before removal from the mould.