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
1999-03-08
2001-10-09
Mulcahy, Peter D. (Department: 1713)
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...
C524S435000, C523S351000
Reexamination Certificate
active
06300401
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a material having a damping property and masterbatch pellets used for production thereof. More particularly, the present invention relates to a material having a damping property which shows a hill internal loss at around room temperature and has a sufficient strength and hardness. The material having a damping property (hereinafter referred to as “damping material”) of the present invention is mainly used as structural materials of electrical or electronic equipment, casings or bodies of household electric appliances of office automation equipments, parts of various kinds of machines and apparatus, interior parts of vehicles and ships, building materials and the like. It finds particularly useful application to a cartridge half and a cassette half.
As is well known, a damping material is widely used in many fields of industry for the purpose of damping vibration or noise generated from various sources and occasions, for example, vibration or noise which is generated incidental to operation of engine or motor mounted in various kinds of machines and apparatus, for instance, office automation equipments, household electric appliances such as washing machines, dryer, etc., a cartridge half and cassette half of data cartridge tapes, video tapes, audio tapes, etc., disk shells of optical discs, magneto-optical discs, magnetic discs, acoustic optical discs, etc., acoustic equipments, precision machine tools, works plant equipments, and various kinds of vehicles and ships; vibration or noise generated from piping such as water and gas pipes in buildings, ducts of air conditioning systems, etc.; and vibration or noise generated from running of vehicles on road or railway tracks
The damping material is usually offered as a sheet-like material or block-like material produced by kneading and molding a binder resin and filler material such as mica, iron oxide or the like by a suitable molding method such as extrusion molding, calender molding, compression molding, injection molding or cast molding, or it is provided directly as a structural material of electrical or electronic equipments, casings of household electric appliances, office automation equipments, a cartridge half and a cassette half, etc. Namely, as for the using mode of the damping material, it may be used so that a molded sheet-like material or block-like material is stuck to or put between pertinent section(s) of an objective apparatus, etc., or it may be directly applied as a structural material of electrical or electronic equipments, casings of household electric appliances, office automation equipments, a cartridge half, a cassette half, etc.
Recently, there is seen a remarkable trend toward the miniaturization and lightweight of handy apparatus such as office automation equipments and acoustic equipments, and a damping material used in such machines, equipments, appliances and tools has been strongly required to miniaturize and reduce the weight. To meet this requirements, the damping materiel is demanded to have a high damping property, that is, a high internal loss. However, if it is simply tried to increase the amount of inorganic filler material used in the damping material for the only purpose of improving damping property, it invites a reduction of strength and hardness of rigid resin used as binder resin, and moldability of the material is impaired. Further, since specific gravity of the produced damping materiel elevates, this runs counter to the requirements of the miniaturization and lightweight It is thus strongly required of damping material to have an excellent damping property while maintaining an intrinsic strength (e.g. bending strength) and hardness of a rigid resin. This fact is referred to in, for instance, Japanese Patent Application Laid-open (KOKAI) No. 4-45142 which states: “As thermoplastic resin composition having damping properties, there are known compositions obtained by blending a large amount of filler material such as calcium carbonate with polypropylene. These compositions, however, had the disadvantages in that the intrinsic priorities of resin (such as good moldability and high impact strength) are deteriorated because of blending of a large amount of filler material. Development of a damping materiel capable of retaining the intrinsic properties of resin has, therefore, been desired”
Recently, large numbers of the movable parts such as motors, relays, transforms, gears, cums, gear boxes and the like, and the electrical, electronic or machine parts which generate vibration and/or noise are used in the household electric appliances or the office automation equipments. The vibration generated from such parts is transferred to other parts and/or casings, and as a result, the intended performances of the product can not be exhibited. According to circumstances, it may be invite to malfunction and/or generate unpleasant vibration. So, the damping material used as a structural material of the electrical, electronic or machine parts, and the casings of the household electric appliances or the office automation equipments is strongly required to have a sufficiently high strength and hardness, and excellent internal loss at around room temperature (e g., 20 to 28° C.).
Also, in recording media such as optical disks or magnetic disks used in computers, word processors and the like, data-cartridge tapes, video and audio optical disks, cassette tapes, etc., higher reliability, tone quality and picture quality of the recording media are strongly demanded.
These recording media are set in a recorder and driven to run by a motor or other motive force to make recording or reading-out. Vibration generated in the inside of the cartridge half or cassette half (for example, vibration caused by “play” around a shaft such as hub for taking up the magnetic tape) or vibration from a source outside the cartridge half or cassette half (for example, vibration caused by operation of motor) exerts baneful influence on recording and reading-out, so that it is difficult to have accurate recording and reading-out of information. Therefore, the damping material used as a structural material for cartridge half or cassette half is strongly required to satisfy the above requirement, i.e., to have an excellent internal loss at around room temperature while maintaining high strength and hardness.
As binder resin for damping material, there are usually used thermoplastic resins (rigid resins) such as polypropylenes, polystyrenes, acrylonitrile-butadiene-styrene copolymers, polycarbonates, polyphenylene ethers, modified polyphenylene ethers and the like. These rigid resins are preferably used because of relatively low cost and excellent molding workability.
These rigid resins, however, are not satisfactorily excellent in internal loss at around room temperature.
Many attempts have been made for improving a damping property of these rigid resins. For instance, Japanese Patent Application Laid-open (KOKAI) No. 2-3.00250 proposes a polypropylene composition improved in a damping property obtained by incorporating a styrene-isoprene-styrene block copolymer in polypropylene resin. Japanese Patent Application Laid-open (KOKAI) No. 3-45646 proposes an ABS resin composition having improved damping property, obtained by incorporating a styrene-isoprene-styrene copolymer to an acrylonitrile-butadiene-styrene copolymer. Japanese Patent Application Laid-open (KOKAI) No. 3-181552 proposes a polyphenylene ether resin composition having excellent damping properties, comprising a polyphenylene ether and a styrene-isoprene-styrene block copolymer. Japanese Patent Application Laid-open (KOKAI).No. 5-70699 proposes a thermoplastic resin composition with improved damping property, obtained by incorporating a styrene-isoprene-styrene block copolymer in a thermoplastic resin. Also, in Japanese Patent Application Laid-open (KOKAI) No. 5-592.34 is proposed a damping material resin composed of polypropylene and a styrene-isoprene-styrene block copolymer.
More specifically, Japanese KOKAI
Fujii Yasuhiko
Moriya Tomohisa
Takaragi Shigeru
Toda Tetsuro
Mulcahy Peter D.
Nixon & Vanderhye
Toda Kogyo Corporation
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