Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-12-09
2002-10-01
Kuhns, Allan R. (Department: 1732)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S094000, C521S134000, C521S140000, C521S150000
Reexamination Certificate
active
06458863
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a shock absorbing, vibration damping, resinous (resin made or containing), open cell cellular body for use in forming floor coverings, sports goods such as sport shoes and pads, and so forth.
BACKGROUND ART
A vibration damping cellular body has been used, utilizing its being soft and having good vibration damping capacity, in sports goods such as sport shoes and pads, floor coverings, daily necessaries and so on in order to increase their shock and vibration absorption properties. A vibration damping property of polymer utilizes the phenomenon that the a polymer exhibits a viscoelastic behavior in the vicinity of its glass transition temperature and in the vicinity of its secondary transition temperature lower than that temperature, increasing greater in its internal friction and, hence its vibration damping capacity.
Polyurethane foam vibration damping materials have so far been made available. For example, a vibration damping material for use in ceiling, floor and so on, that is designed to possess both vibration damping and sound absorption performance by using a predetermined amount of a foam regulator in making a soft polyurethane foam has been proposed (Japanese patent publication No. H05-8209 B). A sound absorbing and vibration damping foam material that is sought to be obtained by foaming an organic polyisocyanate and a particular type of polyol in the presence of a foaming agent, a catalyst, a foam regulator and a fluid having a plasticizing effect has also been proposed (Japanese patent publication No. H07-25863 B).
While these polyurethane foam vibration damping materials are sought to excel in vibration damping properties, they are found to be defective because of their poor resistances to climate or weather and water.
Rubber or elastomer vibration damping foams have also been proposed. For example, 1,2-polybutadiene foams that excel in vibration damping properties, are slow in recovering speed to excel in shock absorbing characteristics and excel in mutual solubility with a thermoplastic resin are sought to be produced by a certain method of manufacture (JP No. H07-62130 A). Further, a vibration damping, resinous foam has also been proposed that is obtainable by crosslinking and foaming a molded mixture of 1,2-polybutadiene having vibration damping capacity and vinyl combined polyisoprene polystyrene block copolymer also having damping capacity (Japanese patent publication No. H08-208869 A).
These conventional 1,2-polybutadiene series foams are closed-cell foams, however, and fail to be an open cell cellular body and may thus have only limited applications. Further, the presence of double bonded carbon atoms of a vinyl radical or a group on the side chains of 1,2-polybutadiene in such compositions makes crosslinking between the side chains together and between the main chain and side chains liable to occur. The compositions thus are defective because they cure rapidly and become deficient in stretchability and flexibility,
SUMMARY OF TEE INVENTION
It is accordingly an object of the present invention to provide a vibration damping, resinous, open cell cellular body that has excellent resistance to climate or weather, is waterproof, and has the propertise of stretchability and flexibility.
Another object of the present invention is to provide a method of making a vibration damping, resinous, open cell cellular body that has properties as described above.
In accordance with the present invention, in a first aspect thereof there is provided a vibration damping, resinous, open cell cellular body with a base material thereof which consists essentially of a mixture of a tri-block copolymer as a combination of polystyrene and vinyl-polyisoprene, and an ethylene series resin.
According to a specific feature of the present invention, it is preferred that a vibration damping, resinous, open cell cellular body as described above, the mixture contain 30 to 95 parts by weight of a tri-block copolymer as a combination of polystyrene and vinyl-polyisoprene, and 70 to 5 parts by weight of an ethylene series resin.
It has been found that the tri-block copolymer described above if contained in less than 30 parts by weight tends to reduce the vibration damping capacity of the cellular body and if contained in more than 95 parts by weight tends to make the cellular body less satisfactory to achieve kneading of the mixture, especially homogeneously.
In accordance with the present invention, in a second aspect thereof there is also provided a method of making a vibration damping, resinous, open cell cellular body, comprising the steps of: blending and kneading with a foaming agent and a crosslinking agent, a mixture of a tri-block copolymer as a combination of polystyrene and vinyl-polyisoprene and an ethylene series resin to form a foamable and crosslinkable composition; heating the composition in a non-airtight mold to permit it to foam, thereby forming a cellular body; and mechanically deforming the cellular body to cause the cells in the body to be interconnected, thereby producing the open cell cellular body.
According to a specific feature of the present invention, it is preferred that in a method of making a vibration damping, resinous, open cell body as described above the mixture contain 30 to 95 parts by weight of a tri-block copolymer as a combination of polystyrene and vinyl-polyisoprene, and 70 to 5 parts by weight of an ethylene series resin.
A tri-block copolymer as a combination of polystyrene and vinyl-polyisoprene as in the present invention has a glass transition temperature (Tg, or absorption of tan &dgr;) in a room temperature range and exhibits high vibration damping performance in such a temperature range.
Thus, according to the present invention in which a tri-block copolymer as a combination of polystyrene and vinyl-polyisoprene is used that has a glass transition temperature (Tg, or absorption of tan &dgr;) in a room temperature range and exhibits high vibration damping performance in such a temperature range, it has been found that a resinous, open cell cellular obtained exhibits high vibration damping performance and shape recoverability and are excellent in vibration damping capacity and also in stretchability, flexibility, climate or weather resistance, and has desirable waterproof and sound insulating properties and is therefore useful for applications, e. g., in forming sports goods such as sport shoes, and also floor coverings.
It has also been found that the tri-block copolymer for use in the present invention should preferably have hydrogen added In its vinyl-polyisoprene phase to provide an open cell cellular body having better resistance to climate or weather.
It has been found that an ethylene series resin as used in the present invention serves to bind the components of a tri-block copolymer together and also to impart to the composition the ability to break or destruct a cell membrane in a cellular structure. While the ethylene series resin may be a low density polyethylene processed under a high pressure, a low density processed under. a low pressure, a medium density polyethylene, a high density polyethylene, ethylene-vinyl acetate copolymer, or a polyethylene series resin polymerized by using metallocene catalyst and so forth, it has been found that ethylene-vinyl acetate copolymer is preferred to provide better cellular interconnection and shape recoverability.
In the method of making a vibration damping, resinous, open cell cellular body according to the present invention, as described above a base material resin is blended with and kneaded together with a foaming agent and a crosslinking agent to form a foamable and crosslinkable composition, which is then heated and thereby foamed to produce a cellular body. Then, by mechanically deforming the cellular body, the cells therein are allowed to inter-communicate. It may be noted that a similar method is described in JP No. S62-19294 B and JP No. H01-44499 B. In the methods described in these prior art literature as well, a foamable and crosslink
Maruo Shusaku
Yoshimura Koji
Frishauf Holtz Goodman & Chick P.C.
Kuhns Allan R.
Sanwa Kako Company Limited
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