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
2001-07-27
2003-02-25
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S240000
Reexamination Certificate
active
06525138
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermoplastic resin composition superior in flexibility, heat resistance and moldability (processability).
BACKGROUND OF THE INVENTION
A thermoplastic elastomer comprising EPOM and a thermoplastic resin is extensively used as a recyclable olefin elastomer.
However, in producing said thermoplastic elastomer, a step of cross-linking EPDM contained in the thermoplastic elastomer is required from a viewpoint of performances of the obtained thermoplastic elastomer such as flexibility, processability, handling facility and recyclability. As a result, there are left problems in that (1) production steps are troublesome, (2) a production cost is high, (3) an odor is generated in the cross-linking step, and (4) the product is easily contaminated with foreign matters caused by the cross-linking.
An object of the present invention is to provide a thermoplastic resin composition, which can be produced without such a cross-linking step, and is superior in flexibility, heat resistance and recyclability and also in moldability such as extrusion moldability, calendering moldability, blow moldability, foaming moldability, injection moldability and inflation moldability.
The present inventors have found a fact that a combination of a specific thermoplastic resin and a specific olefin (co)polymer can give a thermoplastic resin composition capable of attaining the above-mentioned object, and thereby the present invention has been obtained.
SUMMARY OF THE INVENTION
The present invention provides a thermoplastic resin composition comprising:
(A) 5 to 95% by weight of a thermoplastic resin having a melt flow rate of from 0.001 to 100 g/10 min. measured at a temperature of 230° C., under a load of 2.16 kg and a die swell ratio of not less than 1.7, and
(B) 95 to 5% by weight of an olefin polymer satisfying the following formula (1),
Ua≦1.5×Sa×(Ta/100)
3.3
(1)
wherein:
(i) Ua is a flexural modulus (MPa) of a resin composition for evaluation measured according to JISK7203, which composition is composed of 50 parts by weight of said olefin polymer and 50 parts by weight of a homopolypropylene resin having a flexural modulus (Sa) of 1400±100 MPa measured according to JIS K7203, a melt flow rate of 12±3 g/10 min. measured at a temperature of 230° C. under a load of 2.16 kg and a peak position (melting point) on crystal melting of 162±2° C. measured by a differential scanning calorimeter (DSC) according to JIS R7122,
(ii) Sa is a flexural modulus (MPa) of said homopolypropylene resin measured according to JIS K7203, and
(iii) Ta is a containing ratio (50% by weight) of said homopolypropylene resin in the resin composition for evaluation, provided that the sum of the component (A) and the component (B) is 100% by weight.
DETAILED DESCRIPTION OF THE INVENTION
A melt flow rate of the component (A), a thermoplastic resin, used for the production of the thermoplastic resin composition in accordance with the present invention is from 0.001 to 100 g/10 min., preferably from 0.01 to 50 g/10 min., more preferably from 0.1 to 20 g/10 min., measured according to JIS K7210. When the melt flow rate exceeds 100 g/10 min., an extrusion molded article produced from the resulting thermoplastic resin composition is deformed according to the lapse of time after molding (that is, results in an inferior shape retaining property). When the melt flow rate is less than 0.001 g/10 min., an extrusion molded article produced from the resulting thermoplastic resin composition becomes inferior in surface smoothness.
A die swell ratio of the component (A) is not less than 1.7, preferably not less than 1.8, more preferably not less than 2.0. When the die swell ratio is less than 1.7, an extrusion molded article produced from the resulting thermoplastic resin composition becomes interior in shape retaining property. How to measure the die swell ratio is as described below.
The component (A) may be a known thermoplastic resin. Examples of the component (A) are polyethylene resins such as high density polyethylene, medium density polyethylene, low density polyethylene and linear low density polyethylene (LLDPE); copolymer resins with ethylene such as ethylene-vinyl acetate copolymer resin, ethylene-methyl methacrylate copolymer resin, ethylene-methacrylate resin copolymer resin, ethylene-acrylate copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-acrylic acid copolymer resin and ethylene-styrene copolymer resin; polypropyrene resins; polybutene resins; poly-4-methyl-pentene-1 resins; polystyrene resins; polyester resins polyamide resins; polyphenylene ether resins; polyacetal resins; polycarbonate resins; cyclic olefin homopolymer resins and cyclic olefin copolymer resins. Of these, polyolefin resins such as polyethylene resins, copolymer resins with ethylene, polypropylene resins, polybutene resins, and poly-4-methyl-pentene-1 resins are preferred. More preferred are polyolefin resins mainly containing an aliphatic olefin having not less than 2 carbon atoms, and much more preferred are those containing mainly an aliphatic olefin having not less than 3 carbon atoms. Polypropylene resins are particularly preferred.
Examples of the above-mentioned aliphatic olefin having not less than 2 carbon atoms are ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and 4-methyl-pentene-1. From an industrial point of view, an aliphatic olefin having 2 to 8 carbon atoms is preferred. A content of a structural unit derived from the aliphatic olefin having not less than 2 carbon atoms in the component (A) (such a structural unit being hereinafter referred to as “aliphatic olefin unit of not less than 2 carbon atoms”) is preferably not less than 60% by weight, more preferably not less than 70% by weight, much more preferably not less than 80% by weight. When the content is less than 60% by weight, it may happen that the resulting thermoplastic resin composition becomes inferior in its heat resistance.
The “polypropylene resin” means a propylene homopolymer resin and a copolymer resin of propylene and at least one olefin selected from ethylene and olefins having 4 to 12 carbon atoms, which copolymer resin has a propylene unit content of from 60 (inclusive) to 100(exclusive)% by weight in the resin.
As the polypropylene resin, a crystalline polypropylene resin having mainly an isotactic or syndiotactic sequence structure is examplified. As the above-mentioned copolymer resin, a random copolymer resin and a block copolymer resin obtainable by multi-stage polymerization are exemplified. A number average molecular weight of the polypropylene resin is not particularly limited, and preferably from 10,000 to 1,000,000.
As an index of the crystallinity of the polypropylene resin, a melting point and a calorie for crystal melting are exemplified. The melting point is preferably from 80 to 176° C., more preferably from 120 to 176° C. The calorie for crystal melting is preferably from 30 to 120 J/g, more preferably from 60 to 120 J/g. When the melting point and the melting calorie are too low, it may happen that the resulting thermoplastic resin composition deteriorates in its heat resistance.
A general process for producing the polypropylene resin includes, for example, a process wherein propylene alone or a combination of propylene and at least one olefin selected from ethylene and olefins having 4 to 12 carbon atoms is subjected to polymerization in the presence of a polymerization catalyst, thereby obtaining the propylene homopolymer or its copolymer. As the polymerization catalyst, (1) a Ziegla-Natta catalyst comprising a combination of a titanium-containing solid transition metal component and an organometal component, (ii) a catalyst comprising a compound of a transition metal belonging to the 4 to 6 groups of the periodic table as an essential ingredient, and (iii) a metallocene catalyst comprising at least one cyclopentadienyl group-carrying compound of a transition metal belonging to the 4 to 6 groups of the pe
Hozumi Hidetake
Johoji Hirofumi
Nishiyama Tadaaki
Nutter Nathan M.
Sughrue & Mion, PLLC
Sumitomo Chemical Company Limited
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