Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-04-29
2001-07-17
Pezzuto, Hellen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S266000, C526S268000, C526S328000, C526S328500, C526S329600, C526S332000
Reexamination Certificate
active
06262214
ABSTRACT:
TECHNICAL FIELD
The present invention relates to organic polymers suitable for optical use and the like; light-inductive materials available for illumination of various meters, various displays, illumination of signboards, and the like; optical disk substrates and optical disks constituted from specific resins; plastic optical fibers which can be used as optical information communication media and the like; modified polycarbonate sheets having improved weather-resistance and a production method thereof; pickup lenses and lenses used for laser beam printers; resin compositions excellent in optical properties, impact-resistance and heat-resistance and resin compositions excellent in optical properties, weather-resistance and oxidation-degradation-resistance; lamp lenses used for head lamps and fog lamps of automobiles, and signal lamps; and sheet molded articles excellent in light scattering property and heat resistance.
BACKGROUND ART
Methacrylic resins have mechanical properties, molding-processability, weather-resistance and the like in good balance, and are used in a variety of fields as sheet materials or molding materials. Further, methacrylic resins also have excellent optical properties such as transparency, low dispersion, low birefringence and the like. Recently, methacrylic resins have, utilizing such properties, widespread uses such as disk materials of video disks, audio disks, unrewritable disks used in computers, lens materials of video cameras, projection type televisions, light pickup lenses and the like, and various light transmission materials such as optical fibers, optical connectors and the like.
However, methacrylic resins have problems that hygroscopic property is high and heat-resistance is low. Namely, a molded article made of methacrylic resin exhibits size variation and warping by moisture absorption and manifests cracking by repeated cycles of moisture absorption and drying for a long period, and use of methacrylic resins is restricted for some specific articles. Such problems are said to be significant particularly for disk materials, and light pickup lenses and connectors and the like used in such optical systems. Further, use of methacrylic resins in articles used in automobiles is sometimes restricted due to low heat-resistance. Moreover, the same problems are found in acrylic sheets. Recently, lower birefringence is required in optical resin materials such as disk materials, lens materials and the like due to higher density of recording media, and the birefringence of polymethyl methacrylate (hereinafter, abbreviated as PMMA) may be insufficient in some specific fields.
Accordingly, there have been many suggestions recently for improvement of the hygroscopic property, enhancement of heat-resistance, lower birefringence and the like while retaining the optical properties of methacrylic resins. For example, for methacrylic resin less hydrophic, there have been suggested a copolymer composed of methyl methacrylate and cyclohexyl methacrylate (Japanese Patent Application Laid-Open (JP-A) No. 58-5318), and a copolymer composed of methyl methacrylate, cyclohexyl methacrylate and benzyl methacrylate (JP-A No. 58-13652). However, they have a demerit of lowered heat-resistance even though the low hygroscopic property is improved. Further, for imparting heat-resistance and low birefringence, there have been suggested a copolymer composed of methyl methacrylate and o-methylphenylmaleimide (JP-A No. 60-217216) and a copolymer composed of methyl methacrylate and a maleimide compound (JP-A No. 61-95011). However, also in these cases, the copolymers have such demerits that coloration is generally significant, due to introduced maleimide-based monomers.
On the other hand, there is a method in which heat-resistance is improved by suppressing molecular motion via use of a hard polymer chain. A polymer having a backbone pyran ring has been suggested as such polymer (U.S. Pat. No. 4,899,948 and Lon J. Mathias. Polymer. 35(15). 3317. 1994). However, this polymer is made of a methyl ester, isobonyl ester, trimethylcyclohexyl ester and the like, and has fairly high birefringence and can not be subjected to usual injection molding due to low mechanical strength. Further, the copolymer disclosed in this literature is a cross-linked polymer and a molded article thereof is not thermally melted and consequently melt molding is impossible. Also, a copolymer has been suggested which can be melt-molded owing to increased monomer purity (U.S. Pat. No. 5,247,035).
Further, a transparent thermoplastic resin having high ability is required in various fields including optical used and automobile use. Among others, materials of lenses for laser beam printers are required to have various properties further increased in order to obtain clear images. Particularly, low hygroscopic property, low birefringence and high heat-resistance are most important properties.
At present, glass and plastic materials are mainly used as lens materials. However, glass materials can not be recognized to have excellent mechanical strength, mass-productivity and cost performance.
Under such circumstance, a transparent thermoplastic resin, PMMA is frequently used as a lens material now in view of its strength and productivity. Though this PMMA has low birefringence, it has problems of high hygroscopic property and low heat-resistance. That is, because of size variation caused by water absorption, strain is formed in projecting a laser beam to a drum and quality of images tends to lower. Size variation is also caused by heat.
Since the beginning of the market for compact disks (CD) and laser disks (LD) at the beginning of 1980s, optical disks have been in steep increase. Recently, it has become desirable to record in digital mode dynamic images having a volume corresponding to LD in an optical disk in CD size, and a variety of thin disks having raised density are in development (lectures 17p-T-11 and 17p-T-13 in The Society of Applied Physics (Oyo butsuri Gakkai), lectures 29-a-B-8 and 29a-B-5 in The Society of Applied Physics, and the like).
Substrates of such optical disks are molded by an injection molding method which is inexpensive and capable of mass production, and PMMA and polycarbonate have been suggested as resin materials for substrates.
Regarding the plastic optical fiber (hereinafter, referred to as “POF”), PMMA is mainly used as a core material thereof since it has low transmission loss and mechanical properties and weather-resistance thereof present no problem. Upper limit temperature in use of an optical fiber containing PMMA as a core material is at most about 105° C. even when this fiber is endowed with coating excellent in weather-resistance, and heat-resistance thereof is insufficient for communication in movable bodies such as automobiles, electric cars, airplanes and the like and for outdoor use.
For improving heat-resistance of POF, there is a method in which a core material having high Tg is used. As the core material having high Tg, there are known 1) a material comprising a polycarbonate which itself exhibits high glass transition temperature (JP-A No. 61-262706), 2) a material comprising an olefin-based copolymer containing polycyclic olefin-based monomer (JP-A No. 61-211315), 3) a material comprising a methyl methacrylate/aromatic maleimide copolymer (Japanese Patent Application Publication (JP-B) Nos. 5-82405 and 5-82406), 4) a material comprising a methyl methacrylate/aliphatic maleimide copolymer (JP-A No. 63-80205), and 5) a material comprising a methyl methacrylate/alicyclic methacrylate copolymer (JP-A No. 61-260205).
For illuminating a meter panel mounted on a vehicle, airplane and the like, a light-inductive material made of an inorganic glass or transparent resin material is used. This light-inductive material carries a side face as a receptive surface, and a light emitted from a light source placed near the reception surface is introduced as an incident light into the light-inductive material and reflected on a reflection layer such as an aluminum deposited layer and t
Tokimitsu Toru
Tone Seiji
Yanagase Akira
Mitsubishi Rayon Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pezzuto Hellen L.
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