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
2001-04-10
2003-07-08
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S100000, C524S506000
Reexamination Certificate
active
06590032
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to thermoplastic resin compositions. More particularly, this invention relates to a thermoplastic resin composition that exhibits an excellent moldability, an excellent surface lubricity, and an excellent scratch and mar resistance. This invention also relates to moldings comprising this thermoplastic resin composition.
BACKGROUND OF THE INVENTION
Thermoplastic resins offer the advantages of light weight and good corrosion resistance and as a consequence are used for interior and exterior components in automobiles and for the exterior components of household electrical appliances. However, these thermoplastic resins, and thermoplastic elastomers in particular, suffer from a poor surface lubricity and a poor wear or abrasion resistance, and it is fairly easy to scratch or mar the surface of moldings produced therefrom. In order to address these shortcomings in thermoplastic resins, quite a few compositions comprising polyorganosiloxane/thermoplastic elastomer blends have been disclosed. For example, Japanese Patent Application Laying Open Number Sho 60-76561 (76,561/1985) teaches a composition comprising the addition of silicone oil and polytetrafluoroethylene powder to polyolefin-type thermoplastic elastomer. This composition has an enhanced surface lubricity and an enhanced resistance to wear and abrasion. Japanese Patent Application Laying Open Number Hei 11-35750 (35,750/1999) teaches a composition comprising a blend of polyorganosiloxane having a viscosity of at least 100,000 centistokes in a polyolefin-type thermoplastic elastomer. Moldings obtained from the former composition, however, exhibit a number of drawbacks that derive from the fact that the silicone oil outmigrates to the surface thereof and the moldings can become sticky and they may suffer from a loss of aesthetics in their appearance due to an increased gloss. In addition, their surface lubricity can gradually decline during long-term use. In the case of the latter composition, it is difficult to achieve a uniform dispersion of the polyorganosiloxane in the polyolefin-type thermoplastic elastomer, which results in a poor blend stability. Moldings therefrom also suffer from a gradual decline in surface lubricity during long-term use. In addition, Japanese Patent Application Laying Open Number Hei 8-58043 (58,043/1996) teaches a composition obtained by blending polyolefin resin with calcium carbonate and organosiloxane-modified polyolefin resin. Japanese Patent Application Laying Open Number Hei 9-40841 (40,841/1997) teaches a composition comprising a blend of polyorganosiloxane-grafted acrylonitrile-styrene copolymer in acrylonitrile-butadiene-styrene copolymer (ABS resin). Unfortunately, moldings fabricated from these latter compositions suffer from an inadequate surface lubricity and scratch or mar resistance and as a result may not be fully satisfactory for some applications.
The object of this invention is to provide a thermoplastic resin composition that has an excellent moldability, an excellent surface lubricity, and an excellent scratch or mar resistance.
SUMMARY OF THE INVENTION
A thermoplastic resin composition comprising
(A) 100 weight parts thermoplastic resin,
(B) 0.1 to 100 weight parts of a mixture of
(b-1) thermoplastic resin and
(b-2) polyorganosiloxane that has a viscosity at 25° C. of at least 1,000,000 mPa·s, and
(C) 0.1 to 100 weight parts polyorganosiloxane-bonded thermoplastic resin in which
(c-1) thermoplastic resin and
(c-2) polyorganosiloxane
are chemically bonded to each other.
This invention also relates to moldings obtained by the molding or forming of the thermoplastic resin composition.
DESCRIPTION OF THE INVENTION
The present invention is a thermoplastic resin composition comprising
(A) 100 weight parts thermoplastic resin,
(B) 0.1 to 100 weight parts of a mixture of
(b-1) thermoplastic resin and
(b-2) polyorganosiloxane that has a viscosity at 25° C. of at least 1,000,000 mPa·s, and
(C) 0.1 to 100 weight parts polyorganosiloxane-bonded thermoplastic resin in which
(c-1) thermoplastic resin and
(c-2) polyorganosiloxane
are chemically bonded to each other.
This invention also relates to moldings obtained by the molding or forming of the present thermoplastic resin composition.
To explain the preceding in greater detail, the thermoplastic resin (A) may be any organic resin that, while occurring as a solid at ambient temperature, can undergo plastic deformation upon an increase in temperature. The type and other characteristics of this thermoplastic resin (A) are not otherwise critical. Within this broad range of permissible thermoplastic resins, the thermoplastic resins known as thermoplastic elastomers are preferred for (A). Thermoplastic elastomers are organic resins that exhibit rubbery elastic behavior at ambient temperature, but which can undergo plastic deformation upon an increase in temperature (see
Jitsuyo Purasuchikku Jiten
(English title:
The Practical Plastic Encyclopedia
), pages 180 to 207, published 1 May 1993 by Kabushiki Kaisha Sangyo Chosa-kai). These thermoplastic elastomers can be exemplified by polyolefin-type thermoplastic elastomers, polystyrene-type thermoplastic elastomers, polyamide-type thermoplastic elastomers, polyester-type thermoplastic elastomers, polyvinyl chloride-type thermoplastic elastomers, polyurethane-type thermoplastic elastomers, and fluoropolymer-type thermoplastic elastomers; among which the polyolefin-type thermoplastic elastomers, polystyrene-type thermoplastic elastomers, and polyester-type thermoplastic elastomers are preferred. The polyolefin-type thermoplastic elastomers are particularly preferred. The polyolefin-type thermoplastic elastomers include polymer copolymer-type thermoplastic elastomers and polymer blend-type thermoplastic elastomers in which the hard phase is polyethylene or polypropylene and the soft phase is EPDM, EPR, or butyl rubber. These polyolefin-type thermoplastic elastomers are available commercially under such product names, for example, as Mirastomer® and Goodmer, both from Mitsui Petrochemical Co., Ltd. The polystyrene-type thermoplastic elastomers include block polymer-type thermoplastic elastomers in which the hard phase is polystyrene and the soft phase is polybutadiene, polyisobutylene, or hydrogenated polybutadiene; these polystyrene-type thermoplastic elastomers are available commercially under such product names, for example, as Tuftec®, Tufprene®, Sorprene, and Asaprene®, all from Asahi Chemical. The polyester-type thermoplastic elastomers include block polymer-type thermoplastic elastomers in which the hard phase is polyester and the soft phase is polyether or polyester. These polyester-type thermoplastic elastomers are available commercially, for example, under the product name Hytrel® from Du Pont-Toray Co., Ltd. Component (A) can be a single thermoplastic resin or thermoplastic elastomer or can be a mixture of 2 or more. Component (A) preferably has a Rockwell hardness (R scale) at 25° C. no greater than 70 and preferably has a Shore D hardness (ASTM D2240) at 25° C. no greater than 45.
Component (B) is an essential component that imparts moldability and surface lubricity to the present composition. The thermoplastic resin (b-1) encompassed by component (B) can be exemplified by polyolefin resins such as polyethylene (PE), low-density polyethylene (LDPE), high-density polyethylene, ultrahigh molecular weight polyethylene (UHMPE), polypropylene (PP), polymethylpentene (MPX), ethylene-(meth)acrylate ester copolymers, and ethylene-vinyl acetate copolymers (EVA); acrylic-type vinyl resins such as polymethyl methacrylate (PMMA); styrene-type vinyl resins such as polystyrene (PS), high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) copolymers, acrylonitrile-styrene (AS) copolymers, acrylonitrile-acrylic rubber-styrene (AAS) copolymers, and acrylonitrile-ethylene/propylene rubber-styrene (AES) copolymers; other vinyl resins such as polyvinyl acetate, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), and
Furukawa Haruhiko
Morita Yoshitsugu
Shiromoto Koji
Ueki Hiroshi
Dow Corning Toray Silicone Co. Ltd.
Moore Margaret G.
Zombeck Alan
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