GB1160198A - Extended Block Polymer Compositions - Google Patents

Abstract

1,160,198. Block polymer compositions. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 17 July, 1968 [19 July, 1967], No. 34003/68. Heading C3P. An elastomeric composition having at least one glass transition temperature above 35‹ C. comprises: (a) 100 parts by weight of a block copolymer having the general configuration A-B-A wherein each A is an independently selected non-elastomeric polymer block of a mono-vinyl substituted aromatic hydrocarbon, the block having an average molecular weight between 8,000 and 400,000 and the total A block content being from 50 to 80% by weight of the copolymer; and B is a polymer block of a conjugated diene having an average molecular weight between 10,000 and 200,000; and (b) 20-200 parts by weight of an extender selected from mineral oils having an aromatic carbon atom content of less than 25% by weight, mono-olefin polymers having an average molecular weight between 300 and 2500, conjugated diene homopolymers having an average molecular weight between 1000 and 50,000, copolymers of a monovinyl substituted aromatic hydrocarbon and a conjugated diene having average molecular weights between 5000 and 50,000 and mixtures thereof; the weight ratio of the extender to the polymer block B of the block copolymer A-BA being less than 5: 1, the weight ratio of the polymer blocks A of the block copolymer A-B-A to the sum of the polymer block B plus extender being less than 1: 1 and the ratio of the per cent elongation at break to the per cent set at break of the total composition being greater than 10: 1. A is polystyrene, B homopolymers of butadiene, isoprene, dimethyl butadiene and copolymers of these with monovinyl substituted aromatic hydrocarbon (styrene). The block polymers may be built up in ether-free systems with the aid of a lithiumbased initiator such as secondary butyllithium, isoamyllithium or isopropyllithium and, according to one method, a coupling agent such as a dihalohydrocarbon. Examples are directed to elastomeric compositions wherein the block copolymer (100 parts) has the general configuration polystyrenepolybutadiene-polystyrene and the extender (50-150 parts) is either a mineral oil from which aromatic constituents had been extracted with selected solvents or a white oil produced by treating mineral oil with a strong mineral acid. The extender is incorporated into the block copolymer at temperatures of from 60‹ to 130‹ C. Other modifying components such as polymers (polystyrene, polyethylene or polypropylene), resins, asphaltic bitumens, fillers, stabilizers and carbon black may also be included. The compositions may be applied to the manufacture of plastisols, films, linings, laminates or mouldings. They may be incorporated in polystyrene. either physically or by inter-polymerization with polystyrene to form high impact products.