| 摘要 |
1,198,878. Cross-linked olefin-vinyl ester copolymers. LEUNA-WERKE " WALTER ULBRICHT " VEB. 18 Nov., 1968, No. 54612/68. Headings C3C, C3P. Copolymers of an olefin and a vinyl ester are cross-linked by mixing and heating at 60- 250‹ C. with a cross-linking agent which has the formula Me(OR)x, wherein Me denotes a metal of valency x, which is 2-5, and R is an aliphatic or cycloaliphatic group. Suitable crosslinking agents are methylates, ethylates, propylates or butylates of beryllium, magnesium, calcium, zinc, titanium, zirconium, tin, antimony or iron. Higher alcoholates, such as stearylates, palmitylates or cyclohexyl alcoholates, may be used and the esters formed in such cases may be left in the cross-linked copolymer to function as a softener. The cross-linking agent may be added as a master batch i.e. in the form of a mixture of the copolymer with surplus alcoholate, or as a mixture of the alcoholate with a material inert respect to the alcoholate i.e. an olefin homopolymer. In the examples, (1) polyethylene and a copolymer of ethylene and vinyl acetate are blended arid heated with aluminium isopropylate; (2) as (1) except that dicumyl peroxide is added prior to or simultaneously with the alcoholate to permit selective cross-linking of the polymer; (3) a copolymer of vinyl acetate and ethylene are blended and heated with aluminium tripolmitylate, aluminium ethylate, titanium propylate, methanolic magnesium methylate, aluminium isopropylate (the evolution of isopropyl acetate foams the copolymer) or titanium octylate (in the presence of glass fibres); (4) a master batch of polyethylene and aluminium isopropylate is prepared, and is added to a copolymer of vinyl acetate and ethylene, with heating, whereupon isopropyl acetate escapes as a vapour and causes foaming of the copolymer; and (5) as (4) except that the master batch is prepared by reacting a copolymer of vinyl acetate and ethylene with aluminium isopropylate. The cross-linked copolymer, containing glass fibre filler is formed into slabs of high stability. |
