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
2000-01-26
2002-04-02
Nutter, Nathan M. (Department: 1711)
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...
C524S438000, C524S441000, C524S442000, C524S444000, C524S474000, C524S492000, C525S191000, C525S199000, C525S210000, C525S211000, C525S213000, C525S217000, C525S221000, C525S222000, C525S232000, C525S233000, C525S236000, C525S238000, C525S239000, C525S240000, C525S241000
Reexamination Certificate
active
06365660
ABSTRACT:
The present application is a 371 of PCT/JP98/03358 filed Jul. 28, 1998, which claims priority of Japanese Applications 217171/1997 filed Jul. 28, 1997, 237647/1997 filed Aug. 19, 1997 and 309240/1997 filed Oct. 23, 1997.
TECHNICAL FIELD
The present invention relates to resin compositions and molded or formed products (hereinafter typically referred to as molded products) comprising a vinyl cyclic hydrocarbon polymer, and more particularly to a resin composition excellent in transparency, heat resistance, low water absorption property, adhesion to metal films, and the like, small in birefringence, and moreover excellent in anti-opaque-whitening property under high-temperature and high-humidity environment, and molded products formed of such a resin composition. The resin compositions and molded products according to the present invention are particularly suitable for use as optical parts and medical molded products.
BACKGROUND ART
Vinyl cyclic hydrocarbon polymers such as hydrogenated products obtained by hydrogenating aromatic rings of aromatic vinyl polymers such as polystyrene, hydrogenated products of vinylcyclohexene polymers, and vinylcyclohexane polymers have heretofore been known to be resin materials suitable for use in fields of optical parts and the like of which transparency is required, because they are excellent in transparency, heat resistance, low water absorption property and the like and small in birefringence.
For example, Japanese Patent Application Laid-Open No. 43910/1988 discloses optical disk substrates formed of a noncrystalline thermoplastic resin comprising 80 to 100 wt. % of a vinylcyclohexane polymer containing at least 80 wt. % of a vinylcyclohexane component, and 0 to 20 wt. % of an aromatic vinyl polymer and having a light transmittance of at least 85%, a water absorptivity of at most 0.1 wt. % and birefringence of at most 50 nm. This publication discloses, as a process for preparing the vinylcyclohexane polymer, a process in which an aromatic vinyl polymer is hydrogenated, and a process in which vinylcyclohexane or a derivative thereof is polymerized. Japanese Patent Application Laid-Open No. 132603/1989 discloses optical materials comprising, as a component, a polymer obtained by hydrogenating at least 30% of aromatic hydrocarbon rings in a polymer obtained by (co)polymerizing a vinyl aromatic hydrocarbon compound or the vinyl compound and a monomer copolymerizable therewith.
However, products obtained by molding these vinyl cyclic hydrocarbon polymers have involved a problem that they undergo opaque-whitening under high-temperature and high-humidity environment. More specifically, when optical disk substrates, and optical parts such as plastic lenses formed of these vinyl cyclic hydrocarbon polymers are left to stand for a long period of time under the high-temperature and high-humidity environment, they undergo opaque-whitening, and their transparency is impaired. Since these optical parts are used or stored under various environments, the opaque-whitening under the high-temperature and high-humidity environment is an important problem leading to loss of their intrinsic functions. Medical molded products are often subjected to a steam sterilization treatment after molding, or before use. Medical molded products such as injector cylinders formed of these vinyl cyclic hydrocarbon polymers have involved a problem that they undergo opaque-whitening under high-temperature and high-humidity environment such as steam sterilization treatments, and so the contents cannot be checked upon filling of a medical fluid or use after that.
As a method for preventing opaque-whitening (environmental whitening) of molded products from a transparent thermoplastic resin, Japanese Patent Application Laid-Open No. 76657/1995 has proposed a method in which an incompatible compounding additive such as a rubbery polymer is dispersed in a thermoplastic resin so as to form microdomains having a particle diameter of at most 0.5 &mgr;m. In this publication, polycarbonate, polystyrene, polyethylene, polyester, polypropylene, poly(4-methylpentene-1), etc. are exemplified as the thermoplastic resin. Examples of this publication show that molded products, which undergo no opaque-whitening in a steam test that a sample is heated for 30 minutes with steam of 121° C., and a high-temperature and high-humidity environmental test that a sample is left to stand for 48 hours under environment of 85° C. in temperature and 90% in relative humidity (RH), can be provided from resin compositions with a styrene.ethylene.butadiene.styrene block copolymer finely dispersed in polycarbonate (Examples 1 and 2).
Japanese Patent Application Laid-Open No. 199950/1994 discloses molding materials comprising a vinyl cyclic hydrocarbon polymer low in low-molecular weight component content and residues of transition metal atoms. An Example of this publication shows that the use of a resin composition obtained by blending a small amount of a rubbery polymer into a hydrogenated product of polystyrene can provide injector cylinders that withstand a steam sterilization treatment at 121° C. for 30 minutes (Example 3).
According to the methods disclosed in these known papers, the opaque-whitening under the high-temperature and high-humidity environment can be prevented to some extent. However, it is not sufficient, and it has been extremely difficult to completely prevent opaque-whitening in, for example, such a high-temperature and high-humidity environmental test over a long period of time as required of precision optical parts, and such a repeated steam test as required of medical molded products.
When a thermoplastic resin material is used in optical disk substrates, it is required to have excellent adhesion to a recording film formed of a metal such as nickel (Ni) or aluminum (Al). However, resin materials comprising the conventional vinyl cyclic hydrocarbon polymer have been insufficient in adhesion to such a metallic recording film. More specifically, when a metallic recording film layer is formed on an optical disk substrate formed of such a resin material, and the substrate is then held for a long period of time under high-temperature and high-humidity environment, there has been caused a problem that interfacial separation between the substrate and the recording film occurs due to insufficient adhesion, which appears as blister.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a molded product which is formed of a resin composition comprising a vinyl cyclic hydrocarbon polymer as a main component, is excellent in transparency, heat resistance, low water absorption property, etc. and small in birefringence, and undergoes no opaque-whitening in a high-temperature and high-humidity test over a long period of time and a repeated steam test.
Another object of the present invention is to provide a molded product which is excellent in the above various properties and also adhesion to metal films such as metallic recording films and does not cause interfacial separation even in a high-temperature and high-humidity test over a long period of time.
A further object of the present invention is to provide a resin composition excellent in these various properties.
The present inventors have carries out an extensive investigation with a view toward overcoming the above-described problems involved in the prior art. As a result, it has been found that when molding conditions such as molding temperature and residence time of a resin composition, in which a compounding additive incompatible with a vinyl cyclic hydrocarbon polymer is blended into the polymer, in a molding machine are devised upon the formation of a molded product using the resin composition, a molded product which is excellent in various properties such as transparency, heat resistance, low water absorption property and birefringence, and undergoes no opaque-whitening even in a high-temperature and high-humidity test over a long period of time and a repeated steam test can be provided.
The present inventors have carried
Kohara Teiji
Nagamune Tsutomu
Suzuki Teruhiko
Dinsmore & Shohl LLP
Nippon Zeon Co. Ltd.
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