Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1996-09-23
2001-12-11
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S494000, C525S088000, C525S089000, C525S098000, C525S314000
Reexamination Certificate
active
06329459
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel block copolymers having blocks formed from syndiotactic polystyrene and rubbery elastomeric (co)polymers such as styrene/butadiene or polybutadiene. More particularly, it pertains to the use of an extender such as oil or other low molecular weight components to highly extend syndiotactic polystyrene block-elastomeric block copolymers to produce soft compositions having high temperature resistance and processable mechanical properties.
2. Description of Prior Art
It has been known in the past to extend thermoplastic elastomers with petroleum base oils such as naphthenic, aromatic and paraffinic oils and other low weight molecular organic mataterials in order to reduce costs and to improve the elastomeric properties of certain of the thermoplastic elastomers. In U.S. Pat. No. 5.451,454, owned by the current assignee, a blend of a high-molecular weight block copolymer having a hard block and a soft block and a large volume of oily or low molecular weight material provides a composition having unique softness, adequate mechanical strength and damping properties useful in many industrial applications. The heat resistance of this composition was not adequate for higher temperature applications including many uses in automobiles and electrical appliances.
Japanese Patent Laid Open 93-320280 discloses block copolymers having an anionically polymerized polybutadiene or poly(butadiene/styrene) block and a syndiotactic polystyrene (sPS) block. However, neither this patent or any other prior art patent suggests the use of such a composition with a high oil content to obtain a soft material having a low Shore A hardness
It is extremely desirable to prepare a block copolymer composition having elastomeric characteristics, good mechanical strength, unique softness and utility in high temperature applications.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a composition containing a polystyrene-elastomeric block copolymer having elastomeric characteristics such as improved heat resistance, softness, elasticity and mechanical strength, also being well suited to be molded into industrial materials such as electric and electronic materials, industrial construction materials, car parts, domestic electrical appliances and various mechanical parts.
A composition containing an extended block copolymer having blocks formed from (1) a syndiotactic polystyrene and (2) an elastomeric composition such as polybutadiene or styrene/butadiene is produced according to the present invention. This composition is greatly improved in heat resistance, mechanical strength without detriment to the softness and elasticity of the composition. The extended block copolymers of the present invention contain: (1) at least one elastomeric block and (2) at least one syndiotactic polystyrene block which comprises 100 parts by weight of a block copolymer comprising 1 to 80% by weight of syndiotactic poly(vinyl aromatic hydrocarbon) block(s), preferably syndiotactic polystyrene (sPS) block(s), and 99 to 20% by weight of rubbery elastomeric block(s) and at least 30 parts by weight, preferably 30 to about 1000 parts by weight, of an extender such as an oil extender or other low molecular weight component.
DESCRIPTION OF PREFERRED EMBODIMENT
The extended block copolymer compositions of the present invention contain: 100 parts by weight of a block copolymer having 1 to 80% by weight of syndiotactic poly(vinyl aromatic hydrocarbon) block(s), preferably syndiotactic polystyrene (sPS) block(s), and 99 to 20% by weight of rubbery elastomeric block(s) and at least 30 parts by weight, preferably 30 to about 1000 parts by weight, of an extender such as low molecular weight component or an oil extender. In a preferred embodiment the compositions of the present invention are oil-extended block copolymers comprising 10 to 50% by weight of syndiotactic poly(vinyl aromatic hydrocarbon) block(s), preferably syndiotactic polystyrene (sPS) block(s), and 90 to 50% by weight of rubbery elastomeric block(s). If the weight percent of sPS blocks is greater than 80% then the elasticity of the final composition is adversely effected and the miscibility of the block copolymer with the oil or low molecular weight extender is not acceptable. If the weight percent of sPS blocks is less than 1% substantial improvement in heat resistance and mechanical properties are not obtained.
The elastomeric block segments of the block copolymers prepared in accordance with the present invention can be any elastomeric block segment including but not limited to polybutadiene, polyisoprene, styrene/butadiene random copolymer (SBR) preferably having a butadiene/styrene weight ratio of about 85/15 to about 45/55, a styrene/butadiene/styrene block copolymer (SBS), styrene/isoprene block/styrene block copolymer (SIS) and partially or fully hydrogenated versions of these polymers and copolymers. Preferable elastomeric block segments include polybutadiene, random styrene/butadiene copolymers (random SBR), tapered SBR, microblock SBR, random styrene/isoprene copolymer (random SIR), tapered SIR, random styrene/butadiene/isoprene (random SIBR), styrene-ethylene/butylene-styrene block copolymer (SEBS), styrene-ethylene/butylene block copolymer (SEB), styrene-ethylene/propylene-block copolymer (SEP), styrene-ethylene/propylene-styrene block copolymer (SEPS), styrene-ethylene/propylene-ethylene block copolymer (SEPE), styrene-ethylene/butylene-ethylene block copolymer (SEBE), styrene-ethylene/styrene block copolymer (SES), ethylene-ethylene/butylene block copolymer (EEB), ethylene-ethylene/butylene/styrene block copolymer (hydrogenated BR-SBR block copolymer), ethylene-ethylene/butylene/styrene-ethylene block copolymer (hydrogenated BR-SBR-BR block copolymer), ethylene-ethylene/butylene-ethylene block copolymer (EEBE) and the like.
Preferably the elastomeric block segments containing butadiene contributed units in the block copolymers of the present invention contain low vinyl content, or elastomeric block segments containing isoprene contributed units in the block copolymers contain low 3,4-isoprene content, less than a 20% vinyl or 3,4-isoprene content, preferably less than a 10% vinyl or 3,4-isoprene content in the respective butadiene or isoprene contributed units. Such block copolymers compositions with a suitable extender possess superior processability, superior heat resistance and weatherability.
The most preferable elastomer block segments are SBR blocks made by semi-batch techniques and microblock SBR. SBR blocks made by semi-batch techniques are made by a controlled feeding technique, called metering, using little or no modifier to produce a block having a low vinyl content in butadiene contributed units and randomized styrene distribution. Microblock SBR is produced, normally in a batch process, with a potassium-type randomizer such as potassium t-amylate or potassium dodecyl benzene sulfonate as described in U.S. Pat. No. 5,153,159. This system produces low vinyl content in the diene contributed units and a microblock styrene sequence having a peak in the S3 to S8 linear block segments.
Polymerizable 1,3-diene monomers that can be employed in the production of the elastomeric block segment of the block copolymers of the present invention are one or more 1,3-conjugated dienes containing from four to twelve, inclusive, carbon atoms per molecule. Exemplary monomers include 1,3-butadiene, isoprene; 2,3-dimethyl- 1,3-butadiene; 1,3-pentadiene (piperylene); 2-methyl-3-ethyl-1,3-butadiene; 3-methyl-1,3-pentadiene; 1,3-hexadiene; 2-methyl-1,3-hexadiene; 3-butyl-1,3-octadiene; and the like. Among the dialkyl-1,3-butadienes, it is preferred that the alkyl groups contain from one to three carbon atoms. The preferred 1,3-diene monomer for use in the process of the present invention is 1,3-butadiene.
Exemplary vinyl substituted aromatic hydrocarbon monomers, commonly referred to as vinyl aromatic hydrocarbon monomers or VAM, for use in the production of the elas
Clark Frank J.
Kang Jung W.
Luo Xiao-Liang
Mashita Naruhiko
Matsuse Takahiro
Bridgestone Corporation
David G. Burleson
Jude A. Fry
Niland Patrick D.
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