Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-05-21
2000-10-31
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 91, 525191, 525232, C08L 5202
Patent
active
061404187
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a thermoplastic polymer composition comprising a block copolymer formed of an aromatic vinyl compound polymer block and an isobutylene polymer block, and a crosslinked rubber at a predetermined ratio; and molded or formed products, hermetically sealing materials and gaskets for syringe produced from the above thermoplastic polymer composition. The thermoplastic polymer composition according to the present invention can be used effectively for various applications such as hermetically sealing materials such as sealant, gasket and packing material and other molded or formed products, making use of its excellent properties such as formability or moldability, mechanical properties, flexibility, elastic recovery, gas barrier properties, hermetically sealing properties, safety and hygienic properties.
BACKGROUND ART
As a high molecular material having elasticity, generally employed are those obtained by mixing a natural rubber or a synthetic rubber such as diene polymer rubber or olefin polymer rubber (ex. ethylene-propylene-diene copolymer rubber) with a crosslinking agent, reinforcing agent, processing assistant and/or the like and crosslinking the resulting mixture under high temperature and high pressure conditions.
The above-described conventionally-used natural rubber or synthetic rubber however requires steps for crosslinking and molding or forming over a long period of time under high temperature and high pressure conditions so that it is poor in handling properties and productivity. In view of such drawbacks of the natural or synthetic rubber, various thermoplastic elastomers, similar to ordinarily used thermoplastic resins, from which a molded or formed product can be prepared easily by making use of the general-purpose melt molding or forming technique such as hot pressing, injection molding or extrusion have been developed recently.
As the prior art relating to a thermoplastic elastomer or its composition, known are: SHO 58-206644) which is obtained by mixing, with a view toward improving flexibility, thermal deformation resistance and mechanical strength, a block copolymer formed of an aromatic vinyl compound polymer block and a hydrogenated conjugated diene polymer block with a softener for a non-aromatic rubber and a propylene 1-olefin copolymer and optionally an inorganic filler; SHO 59-131613) which is obtained by mixing, with a view toward improving flexibility, resistance to high-temperature compression set, mechanical strength, oil resistance and moldability or formability, a block copolymer formed of an aromatic vinyl compound polymer block and a hydrogenated conjugated diene polymer block with a softener for a non-aromatic rubber and a peroxide decomposition type olefin resin and optionally an inorganic filler; and Laid-Open No. SHO 63-112649), which is obtained by mixing, with a view toward improving flexibility, high-temperature compression set resistance, high-temperature creep properties, mechanical strength, moldability or formability, oil resistance and anti-stickiness, a block copolymer formed of an aromatic vinyl compound polymer block and a hydrogenated conjugated diene polymer block with a softener for a non-aromatic rubber, a polyolefin resin, an olefin copolymer rubber and a reaction type alkylphenol/formaldehyde resin and then, subjecting the resulting mixture to dynamic vulcanization.
The above-described conventional elastomeric compositions (1) to (3) are recognized to have improved moldability or formability, oil resistance and compression set resistance to some extent, but do not have sufficient gas barrier properties, sealing properties and viscosity of the material itself. When these conventional elastomeric compositions are used for hermetically sealing materials such as packing material, sealant, gasket or stopper, they cannot be used effectively as hermetically sealing materials because of liquid leakage from the sealing stopper, liquid leakage after needle insertion and separation of broken pieces from the material
REFERENCES:
patent: 5276094 (1994-01-01), Kaszas et al.
patent: 5721331 (1998-02-01), Shachi et al.
Patents Abstracts of Japan, vol. 008, No. 251 (C-252), Nov. 16, 1984, JP 59 131613, Jul. 28, 1984.
Patents Abstracts of Japan, vol. 017, No. 655 (C-1136), Dec. 6, 1993, JP 05 212104, Aug. 24, 1993.
Kuki Toru
Shachi Kenji
Yamashita Takashi
Asinovsky Olga
Kuraray Co. Ltd.
Seidleck James J.
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