Patent GB-980743-A (GB)
Title: Improvements in or relating to the manufacture of deformable heat-hardenable synthetic resin materials
IPC: C09D151/08
Filed: 1961-02-28
Abstract: A deformable, heat hardenable synthetic resin material is produced by partially polymerizing to a gelled state an unsaturated polyester resin and an allyl monomer using a peroxidic polymerization initiator and an activator comprising a mercaptan and a reducing metal salt. Allyl monomers mentioned are diallyl phthalate, diallyl adipate and diallyl maleate and the preferred polyester is formed from maleic acid and optionally succinic and/or phthalic acid, and ethylene glycol. The preferred activator is lauryl or allyl mercaptan and stannous chloride.  The metallic reducing salt may be dissolved in one or more of dimethylformamide, tetrahydrofuran, dioxane, furfural, ethylene glycol, diethylene glycol, triethylene glycol and liquid higher polyethylene glycols.  Reinforced synthetic resin sheets may be formed by effecting the partial polymerization of the unsaturated polyester resin composition in situ on a sheet of reinforcing material or by impregnating the reinforcing material with the partially polymerized unsaturated polyester resin composition after the latter has been prepared.  The reinforcement may be a fabric which is made from glass fibre or paper, or a metal sheet. The partial polymerization is carried out by heating from 70 DEG  to 80 DEG  C. for up to five minutes and to stop the polymerization the mass is cooled to ambient temperature.  In making a reinforced sheet, the reinforcement may be initially impregnated with the activator, advantageously diluted with a volatile solvent which may be evaporated after impregnation, and then the reinforcement coated with or embedded in a blend of the remaining polyester composition, the impregnated sheets then being heated as above. One or both faces of the final reinforced sheet after partial polymerization may be treated with a polymerization accelerator to obtain a more fully polymerized surface layer.ALSO:Reinforced synthetic resin sheets may be formed by partially polymerizing to a gelled state an unsaturated polyester resin composition in situ on a metal sheet or on glass fibre fabric or on paper.  The unsaturated polyester resin composition comprises an unsaturated polyester resin, an allyl monomer, a peroxidic polymerization initiator and an activator comprising a mercaptan and a reducing metal salt.  The preferred polyester is formed from maleic acid and optionally succinic and/or phthalic acid, and ethylene glycol and the preferred activator is lauryl or allyl mercaptan and stannous chloride.  Alternatively, the metal sheet, glass fabric or paper may be impregnated with the partially polymerized unsaturated polyester resin composition after the latter has been prepared.  In making a reinforced sheet, the metal sheet, glass fibre or paper may be initially impregnated with the activator, advantageously diluted with a volatile solvent which may be evaporated after impregnation, and then the sheet coated with or embedded in a blend of the remaining polyester composition, the impregnated sheet then being heated to from 70-80  DEG C. for up to 5 minutes.  One or both faces of the final reinforced sheet after partial polymerization may be treated with a polymerization accelerator to obtain a more fully polymerized surface layer.ALSO:Reinforced synthetic resin sheets may be formed by partially polymerizing to a gelled state an unsaturated polyester resin composition in situ on paper.  The unsaturated polyester resin composition comprises an unsaturated polyester resin, an allyl monomer, a peroxidic polymerization initiator and an activator comprising a mercaptan and a reducing metal salt.  The preferred polyester is formed from maleic acid and optionally succinic and/or phthalic acid, and ethylene glycol and the preferred activator is lauryl or allyl mercaptan and stannous chloride. Alternatively the paper may be impregnated with the partially polymerized unsaturated polyester resin composition after the latter has been prepared.  In making a reinforced sheet the paper may be initially impregnated with the activator, advantageously diluted with a volatile solvent which may be evaporated after impregnation, and then the sheet coated with or embedded in a blend of the remaining polyester composition, the impregnated sheet then being heated from 70 DEG  to 80 DEG C. for up to 5 minutes. One or both faces of the final reinforced sheet after partial polymerization may be treated with a polymerization accelerator to obtain a more fully polymerized surface layer.