GB1462730A - Mercaptan-terminated polymers and cured polymers derived there from - Google Patents

Abstract

1462730 Mercaptan-terminated polymers; polysulphide polymers PRODUCTS RESEARCH & CHEMICAL CORP 11 Nov 1974 48680/74 Heading C3R A liquid polymer (L) terminated by 2-4 -SH Groups, curable to a solid polysulphide (S), is made by (a) mixing (1) a liquid polymer having 2-4 terminal olefinic double-bonds, (2) an alkaline initiator having no aryl groups, with pK b #6À0, and (3) a compound R(SH) (2 or 3) or H 2 S, the ratio (3) : (1) being 1 mole (3) per olefin equivalent of (1); and (b) reacting at from room temperature to the b.p. of the reactants, in the absence of N 2 , until the olefinic doublebonds disappear. The reaction-mixture contains #0À01% wt. of (2). 0À1-1% wt. of a free-radical initiating catalyst, e.g. t-butyl perbenzoate, may be present. (2) may be diazabicyclo(2,2,2)- octane or tetramethylguanidine. (1) may be made by reacting a polyetherpolyurethane (4) with allyl alcohol or hydroxy ethyl acrylate. Polyurethane (4) may be made by reacting polyoxypropylene triol and optionally diol with a polyisocyanate, e.g. 2,4-TDI. In examples, (3) is ethanedithiol, dimercaptodiethyl ether, or a polysulphide polymer. Liquid polymer (L) may be where x, y and z are H, or optionally halogenated hydrocarbon, alkoxy, or phenoxy; r, s, and t are H or C 1-6 alkyl; m = 1 or 2; n=1-4; p = 0-3; n+p=2-4; R<SP>1</SP> is a radical; R<SP>11</SP> is a group derived from (1) by attachment of the groups indicated; and A is a structural unit of an organic olefinic compound having an active hydrogen, e.g. as OH or amine group, with formula Solid polysulphide (S) may be (L) may be cured to (S) by oxidizing agents, epoxides, or vulcanizing agents; e.g. PbO 2 , CaO 2 , BaO, S, ZnO, bis-phenol A epoxy resins, or dipentamethylene-thiuram-tetrasulphone. (L) may be mixed with, e.g. CaCO 3 , TiO 2 , mercaptosilane, hydrogenated biphenyl, or chlorinated polyphenyl to form a one-part moisture-curable system. There may be dispersed in (L) a moisture-activatable dormant curing-agent and a deliquescent accelerating agent.