TH16974B - Olefin foam products, thermoplastic elastomers? And the processes for preparing them. - Google Patents

Abstract

An olefin thermoplastic elastomer foam product is obtained by heating a foamable component consisting of a specifically partially crosslinked thermoplastic elastomer (A), an olefin plastic (B), and a foaming agent (C) in specific proportions. The partially crosslinked thermoplastic elastomer (A) is obtained by dynamic thermal action on the mixture in the presence of an organic peroxide. The mixture contains specific proportions of a peroxide-crosslinkable copolymer (a), which is the olefin plastic copolymer. Specifically, ethylene/alpha-olefin/non-conjugated diene and peroxide-degradable olefin plastic (b) is a (co)polymer containing 50 to 100% by mole of alpha-olefin of 3 to 20 carbon atoms and has a specific MFR. Olefin plastic (b) is a (co)polymer containing 50 to 100% by mole of alpha-olefin of 2 to 20 carbon atoms and has a specific MFR. The process of preparing the foam product of the olefin thermoplastic elastomer is such that the foam product of this invention is free from surface roughness caused by foam loss, even when the expansion ratio is 2 or more than 2 times. In addition, the foam product is soft to the touch and exhibits excellent heat resistance and weather resistance. According to the process of this invention, the foam product can be prepared by conventional procedures with high yield.

Claims (10)

1. Olefin thermoplastic elastomer foam products obtained by heating a foamable component consisting of [I] 100 parts by weight of some crosslinked thermoplastic elastomer component (A) obtained by dynamic thermal action on the mixture with the presence of organic peroxides. Such mixture consists of 60 to 95 parts by weight of peroxide-crosslinkable olefin copolymer (a), which is an ethylene/alpha-olefin copolymer of ethylene and alpha-olefin of 3 to 20 carbon atoms or an ethylene/alpha-olefin/non-conjugated diene copolymer of ethylene alpha-olefin of 3 to 20 carbon atoms and non-conjugated diene, and 5 to 40 parts by weight of peroxide-degradable olefin plastic (b), which is a homopolymer. or copolymers containing 50 to 100% by mole of alpha-olefin of 3 to 20 carbon atoms and a melt flow rate (ASTM D 1238-65T 230 °C, weight 2.16 g) of 5 to 80 g/10 min. Total amounts of components (a) and (b) are 100 parts by weight [II] 1 to 20 parts by weight of olefin plastic (B) which is a homopolymer or copolymer containing 50 to 100% by mole of alpha-olefin of 2 to 20 carbon atoms and a melt flow rate (ASTM D 1238-65T 230 °C, weight 2.16 g) of 0.01 to 2 g/10 min and [III] foaming agent C. 2. Foam products as claimed under Reputation 1, in which alpha-olefin is composed of ethylene/alpha-olefin copolymer or ethylene/alpha-olefin/nonconjugate diene copolymer, each being an olefin copolymer that is crosslinkable by peroxide (a), in particular propylene or 1-butene. 3. Foam products as claimed under Reputation 1 or Reputation 2 where the peroxide-degradable olefin plastic (b) is isotactic polypropylene or propylene/alpha-olefin copolymer. 4. Foam products as claimed under any of the claims 1 to 3, where the thermoplastic elastomer (A) component is heat-treated with organic peroxides and divanylbenzene to enable partial crosslinking. 5. Any one of the foaming products claimed under claims 1 to 4 in which olefin plastic (B) is isotactic polypropylene or propylene/alpha/olefin copolymer. 6. Any foaming product as claimed under any of the claims 1 through 5, where the foaming agent (C) is a heat-degradable organic or inorganic foaming agent. 7. Any foam product claimed under claims 1 through 6 in which the amount of foaming agent (C) in the foamable component is 0.5 to 20 parts by weight relative to 100 parts by weight of the total thermoplastic elastomer (A) and olefin (B) components. 8. A foaming product as claimed under any of claims 1 through 7, which has an expansion rate of not less than 2 times. 9. The process for preparing an olefin thermoplastic elastomer foam product involves melting a foamable component and then foaming the melted component, where the foamable component is described by any one of Claims 1 through 7. 10. The process claimed in claim 9, whereby the olefin thermoplastic elastomer foam product has an expansion rate of not less than 2 times.