SYNTHETIC MATERIAL MOLDING PROCESS

Abstract

Abstract Process for moulding opt. foamed plastics cush as polyurethanes, esp. of integral skin, flexible, semirigid, rigid or elastomeric type, uses a partially blocked catalytic system comprising (A) a metal salt (pref. of a divalent metal, e.g. dibutyl tin dilaurate, stannous octoate, dibutyl tin diacetate, dibutyl tin maleate, lead naphthenate or octoate) and (B) an amine which is totally neutralised with (C) a chelate type boric complex such as a glycoborate prepd. in presence of excess of glycol. (C) is pref. prepared from a polyol with >=3 OH groups (e.g. glycerol, 1,2,3- or 2,3,4-hexanetriol, trimethylol ethane or propane, 1,2,3-pentanetriol, and H3BO3 or esp. B2O3, excess of glycol being >=75%. (A) and the unstable (B)/(C) complex formed give a synergic effect leading to very short demoulding time (2 mins. c.f. 6-7 mins. previously) without increasing the cream time (approx. 20 secs.) and hence a reduced overall moulding cycle time. The catalyst system gives an initial slow temp. rise. (e.g. 20 degrees C in 24 secs.) due to (A) above followed by a rapid rise (50 degrees C in 18 secs.) due to (A) and liberated (B).

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