GB1138203A - Rubber reinforcing phenolic resin compositions - Google Patents

Abstract

1,138,203. Sulphur-containing phenolic resin compositions. DISTILLERS CO. Ltd. 14 July, 1966 [28 Aug., 1965], No. 37094/65. Headings C3P and C3R. A composition for reinforcing rubber comprises a formaldehyde donor and the reaction product of an ethylenically unsaturated phenolic resin and sulphur or a sulphur chloride. The unsaturated resin is preferably a novolak, e.g. one esterified with an unsaturated acid (e.g. linseed or tall oil acids) or etherified with an unsaturated alcohol or one prepared from a phenol having an unsaturated side chain (e.g. cardanol), and preferably has a ball-and-ring softening point of 80-105‹ C. The formaldehyde donor is preferably solid, e.g. hexamethylene tetramine and preferably amounts to 6-15 wt. per cent of the reaction product. The reaction product conveniently contains 0À25-2À75 atoms of sulphur per double bond initially present in the resin. The resin will react with sulphur at a temperature, preferably of 120-160‹ C., and with sulphur chloride at room temperature or e.g. 70‹ C. in a solvent. The rubber may be natural or synthetic. A vulcanizable rubber mixture contains rubber, a vulcanizing system and a composition of the invention, the latter preferably amounting to 1-100 (better, 1-30) parts wt. per 100 of rubber. In examples, compositions are prepared containing (1) 10 p.b.w. hexamethylene tetramine and 100 p.b.w. of a tall oil fatty acidmodified cresol-formaldehyde resin which has been heated with sulphur, and (2) 12À5 p.b.w. hexamethylene tetramine and 100 p.b.w. of a sulphurized cardanol-cresol-formaldehyde resin. A styrene-butadiene rubber is compounded with ZnO, stearic acid, a carbon black filler and 5, 10 or 20 p.b.w. per 100 of the above compositions, then cured with sulphur and N- cyclohexyl - 2 -benzthiazyl sulphenamide.