Plasticized thermoplastic block copolymers

Abstract

Abstract Novel plasticized thermoplastic copolymers are described wherein said copolymer is selected from the group consisting of block copolymers having the general formulae (I)A-B-A, (II)A-B-A-B-A and (III) xB - (A-B)n - yA, and graft copolymers having the general formula (IV) wherein m and n are integers greater than or equal to 2; x and y are 0 or 1, and y is 0 when n is 2; and A and B are mutually incompatible thermoplastic polymer blocks having a solubility parameter difference of greater than 0.7, preferably greater than 1.0, and said plasticizer is selected from the group consisting of plasticizers having a solubility parameter within 1.2 units of the solubility parameter of said B polymer block. Preferably, the A and B polymer blocks have a molecular weight of at least 5000 and a glass transition temperature of at least 35*C., and in general from 25 to 300 parts plasticizer is added per hundred parts of the copolymers described above to prepare the novel compositions claimed herein. The preferred class of copolymers are prepared from vinyl aromatics. In the most preferred embodiment the copolymer is a styrene-t-butyl styrene-styrene copolymer and the plasticizer is an oil having a low aromatics content, for example an oil of about 1-2 percent aromatic content, 10-13 percent paraffinic content and 82-88 percent naphthenic content is preferred. These oils in this general range are widely available as commercial products and generally have a viscosity at 68*F. of about 1100 SSU (Saybolt), and a specific gravity of about 0.88.

Inventors

• 👤 H Makowski
• 👤 R Lundberg

Bibliographic Details