| 摘要 |
1433237 Coating rubber CHEMISCHE WERKE HULS AG 22 Aug 1973 [23 Aug 1972] 39756/73 Heading B2E A process for coating a vulcanised article of saturated or unsaturated polyolefin rubber wherein the article is first pretreated with an optionally aqueous solution of a strong oxidising agent or by U.V. irradiation, then coated with a composition comprising (a) a saturated oligoester containing hydroxyl groups and having a molecular weight of 250 to 3500, the alcohol component of which comprising 20 to 100 mol % of 1, 4-bis-(hydroxymethyl)cyclohexane and being at least difunctional, and (b) a bifunctional isocyanate and/or a polyfunctional isocyanate, the ratio of 1-NCO groups in the isocyanate to -OH groups in the oligoester being 0.75:1 to 1:1. Preferred rubbers are polyolefin rubbers containing 30 to 40 wt. % ethylene and 70 to 10 wt. % propylene and/or butene-1, optionally also including of multi-unsaturated olefin such as trans-1, 4-hexadiene, dicyclopentadiene, methylene norbornene, ethylidene-norbornene, or propenyl-norbornene. Suitable strong oxidising agents are chromic, peroxyacetic, nitric, acids, nitric acid/hydrochloric acid mixture, chromosulphuric acid, KMnO 4 , chlorine or hypochlorites. The coating may be applied by casting or one- or two-component spraying. The oligoester may comprise 0 to 80 mol. % of other diols e.,g .ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 3- or 1, 4-butanediol, hexanediols or 2-ethyl-1, 3-hexanediol, and up to 40 mol. % of branched polyols such as glycerine, trimethylolpropane or pentaerythritol. Aliphatic dicarboxylic acid mixed with aromatic and/or cycloaliphatic dicarboxylic acids may be used in the oligoester. Examples of aromatic or cycloaliphatic acids are phthalic, isophthalic, hexahydroterephthalic, tetrahydrophthalic or hexahydrophthalic acids, the cycloaliphatic acids being in the trans- or cis-form or a mixture. Examples of aliphatic acids are succinic, glutaric, adipic, suberic, sebacic, decanedicarboxylic acids as well as unsaturated acids such as maleic, fumaric, itaconic and citraconic. The free acids, esters or anhydrides may be used. Typical isocyanate are "Desmodure" (RTH) isophorone-diisocyanate, and trimethylhexanemethylenediisocyanate. The degree of gloss of the coating may be altered with fillers such as colloidally dispersed silica, talc or waxes. |
