| 摘要 |
1,066,440. Moulds. POLYMER CORPORATION. Nov. 27, 1963 [Dec. 4, 1962], No. 46888/63. Heading B5A. A mould for the in situ polymerization of polylactam articles consists of a cured acid-free polysiloxane. The polysiloxane is obtained from a mixture of an organopolysiloxane of formula RnSiO 4-n , preferably a methyl polysiloxane, from 0À1-50% by weight of the siloxane of a hydrocarbonoxy silicate, from 0À01-10% by weight based on the weight of the siloxane of a carboxylic acid salt of metals ranging from lead to manganese inclusive in the electromotive series of metals, and a silica filler. The mould is formed by pouring the polysiloxane around a master or prototype, which is preferably made slightly oversize preferably by heating to compensate for shrinkage on polymerization of the lactams, and then curing the organopolysiloxane, preferably at room temperature. The shaped polylactam articles are formed by charging the polysiloxane mould with a higher lactam and polymerizing said lactam under substantially anhydrous conditions. Preferably the lactam is epsiloncaprolactam, and is put into the mould after it has passed through an incipient polymer formation stage. Preferably the mould is preheated, and an anionic polymerization catalyst, e.g. sodium caprolactam, and a N,N-diacyl tertiary nitrogen promoter compound, e.g. tolylene diisocyanate, are added. Preferably polymerization is initiated above the melting point of the lactam monomer, but below the melting point of the polymer and the maximum polymerization temperature reached is below the melting point of the polymer, the mould being heated during polymerization of the lactam. The mould may be provided with a non-flexible backing. Articles produced include rods, bars, sheets, plates, gears, timing screws, fan blades, roll covers, spheres and drive bushings. |
