Games using tangible projectile – Player held and powered – nonmechanical projector – per se,... – Racket or paddle; accessory therefor
Reexamination Certificate
2000-09-29
2002-09-17
Chiu, Raleigh W. (Department: 3711)
Games using tangible projectile
Player held and powered, nonmechanical projector, per se,...
Racket or paddle; accessory therefor
C473S524000
Reexamination Certificate
active
06450904
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a string for a sports racket, more particularly to a string having a toothed core and a sheath layer molded over the toothed core.
2. Description of the Related Art
A known type of conventional racket string is formed of a plurality of core filaments which are twisted together upon passing through an impregnating container carrying a thermoplastic resin inside for impregnating the filaments so as to increase the elasticity of the string. This type of string generally has poor wear-resistance. When the string is used in a racket, high impact and friction induced upon hitting a ball would result in severe wearing of the string.
Another conventional string is formed of a plurality of core filaments sheathed by a moisture-cured polyurethane which provides hardness to increase the wear-resistance of the string. However, this type of string has poor elasticity. Thus, reactive force produced in the string upon impact may injure the user's hand.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a string for a sports racket that has a structure capable of providing good wearresistance and elasticity.
Accordingly, a string for a racket of the present invention comprises: a toothed core made of a first plastic material and having a toothed outer surface; and a sheath layer made of a second plastic material and molded over the core so as to be bonded to the toothed outer surface. The first plastic material has a hardness and a wear-resistance less than those of the second plastic material.
REFERENCES:
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patent: 4860531 (1989-08-01), Wells et al.
patent: 4956236 (1990-09-01), Want
patent: 5090188 (1992-02-01), Lin et al.
patent: 5327714 (1994-07-01), Stevens et al.
patent: 5922462 (1999-07-01), Kent et al.
patent: 6009699 (2000-01-01), Delvael
patent: 377362 (1990-07-01), None
Chiu Raleigh W.
Townsend and Townsend / and Crew LLP
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