Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2003-04-11
2004-12-21
Harlan, Robert D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S241000, C525S242000, C525S244000
Reexamination Certificate
active
06833411
ABSTRACT:
TECHNICAL FIELD
The present invention relates to thermoplastic resin compositions which are reduced in the formation of a gel (crosslinked polymer) due to a block copolymer crosslinking reaction during molding, are reduced in melt viscosity change due to crosslinking and cleavage of block copolymer chains, and are excellent in suitability for film or sheet forming and suitability for injection molding, and to an asphalt composition which is excellent in high-temperature storage stability and low-temperature characteristics and has an excellent balance among properties. More particularly, the invention relates to resin compositions comprising a specific block copolymer comprising a vinylaromatic hydrocarbon, isoprene and 1,3-butadiene, and at least one thermoplastic resin selected from styrene resins, polyolefin resins and poly(phenylene ether) resins, and to an asphalt composition comprising a block copolymer of a specific structure comprising a vinylaromatic hydrocarbon, isoprene and 1,3-butadiene, and an asphalt.
BACKGROUND ART
Block copolymers comprising a conjugated diene and a vinylaromatic hydrocarbon have satisfactory compatibility with resins such as polystyrene and are advantageously used for improving the impact resistance of these resins.
For example, JP-B-45-19388 and JP-B-47-43618 describe the use of a linear block copolymer or a branched block copolymer as an impact modifier for polystyrene.
On the other hand, it has been attempted to incorporate an olefin resin for the purpose of improving the oil resistance of styrene resins. However, since styrene resins have poor compatibility with olefin resins, there has been a problem that the incorporation results in a composition which suffers a separation phenomenon and has poor mechanical strength. A composition comprising a polyolefin resin and a polystyrene resin and containing a hydrogenated block copolymer has hence been proposed in, e.g., JP-A-56-38338.
Poly(phenylene ether) resins are excellent in mechanical properties, electrical properties, etc. and are extensively used as business apparatus housings, various industrial parts, and the like. Especially for use in applications such as business apparatus and acoustic appliances, where damping performance is required, a poly(phenylene ether) resin composition containing a block copolymer in which the content of 3,4-bonds and 1,2-bonds (vinyl bonds) in the diene units is 40% or higher is disclosed in, e.g., JP-A-3-181552.
Poly(phenylene ether) resins are inferior in oil resistance and impact resistance, and it has been attempted to incorporate an olefin resin in order to improve these properties. However, since these two kinds of resins have poor compatibility, the incorporation has posed a problem that a separation phenomenon occurs. A composition comprising a polypropylene resin and poly(phenylene ether) and containing a hydrogenated block copolymer has hence been proposed in, e.g., JP-A-9-12800.
On the other hand, asphalt compositions are extensively used in applications such as road paving, waterproof sheets, sound insulation sheets, and roofing. Many attempts have been made to improve properties of asphalts for such applications by adding various polymers thereto. For example, JP-B-47-17319 discloses an asphalt composition containing a block copolymer of a vinylaromatic compound and a conjugated diene compound. Furthermore, JP-A-54-57524 discloses an asphalt composition containing a radial teleblock copolymer.
An object of the invention is to provide a resin composition which comprises a block copolymer and a polystyrene resin and/or poly(phenylene ether) resin and which is reduced in gel formation due to a block copolymer crosslinking reaction during molding, is reduced in melt viscosity change due to crosslinking and cleavage of block copolymer chains, and has satisfactory low-temperature impact resistance and excellent suitability for film or sheet forming and injection molding. Another object of the invention is to provide a resin composition which comprises a block copolymer and a polyolefin resin, polystyrene resin, and/or poly(phenylene ether) resin and which has improved impact resistance besides those properties.
A still other object of the invention is to provide an asphalt composition which contains a specific block copolymer comprising a vinylaromatic hydrocarbon and a conjugated diene and which has an excellent balance among properties such as softening point, strength, and workability, is excellent in high-temperature storage stability and low-temperature characteristics, and is suitable for use in road paving applications, roofing/waterproof sheet applications, sealant applications, and the like.
DISCLOSURE OF THE INVENTION
It was found that use of a thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins in combination with a block copolymer comprising a vinylaromatic hydrocarbon, isoprene, and 1,3-butadiene and having a specific polymer structure is effective in reducing the gel formation due to a block copolymer crosslinking reaction during molding to thereby considerably reduce the gel level (fish eyes) and in simultaneously reducing the melt viscosity change due to crosslinking and cleavage of block copolymer chains and attaining excellent low-temperature impact resistance, etc. It was also found that in a composition comprising a combination of a thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins with a specific hydrogenated block copolymer and a block copolymer comprising a vinylaromatic hydrocarbon, isoprene and 1,3-butadiene and having a specific polymer structure, the specific hydrogenated block copolymer improves the compatibility of the styrene resin and/or poly(phenylene ether) resin with the polyolefin resin, while the block copolymer comprising a vinylaromatic hydrocarbon, isoprene, and 1,3-butadiene and having a specific polymer structure blends preferentially with the styrene resin and/or poly(phenylene ether) resin to form a homogeneous mixture and thereby improve impact resistance. The invention has been completed based on these findings.
On the other hand, extensive investigations were made on property improvements in compositions which comprise an asphalt and a block copolymer comprising a vinylaromatic hydrocarbon and a conjugated diene and are to be used in road paving applications, roofing/waterproof sheet applications, sealant applications, or the like. As a result, it was found that an asphalt composition which comprises an asphalt and a block copolymer comprising a vinylaromatic hydrocarbon and conjugated dienes and are excellent in high-temperature storage stability and low-temperature characteristics is obtained by using isoprene and 1,3-butadiene as the conjugated dienes in a proportion within a specific range and so as to result in a specific vinyl bond amount. The invention has been thus completed.
Namely, the invention relates to the following compositions.
(1) A composition comprising:
(A) from 2 to 40 parts by weight of a block copolymer which is a block copolymer having at least two polymer blocks mainly comprising a vinylaromatic hydrocarbon and further having at least one copolymer block comprising isoprene and 1,3-butadiene and/or at least one copolymer block comprising isoprene, 1,3-butadiene and a vinylaromatic hydrocarbon, the block copolymer having a vinylaromatic hydrocarbon content of from 5% by weight to less than 60% by weight and a total content of isoprene and 1,3-butadiene of from more than 40% by weight to 95% by weight, and the block copolymer having an isoprene/1,3butadiene weight ratio in the range of from 95/5 to 5/95, a vinyl bond amount less than 40% by weight, and a number-average molecular weight in the range of from 30,000 to 500,000; and
(B) from 98 to 60 parts by weight of either at least one thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins or an asphalt.
(2) A resin composition obtained by compounding 100 parts by weight of a resin comp
Fujiwara Masahiro
Nakamichi Yukinori
Birch & Stewart Kolasch & Birch, LLP
Harlan Robert D.
Japan Elastomer Co., Ltd.
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