String for use in racket

Abstract

A method of manufacturing a string 10 for use in a racket includes: (A) preparing an untreated string; and (B) irradiating the untreated string with radioactive rays. Preferably, the untreated string is irradiated with gamma rays. A preferable irradiation amount of the radioactive rays is greater than or equal to 250 kGy but less than or equal to 2000 kGy. Preferably, a material of the untreated string is polyester. Alternatively, the material of the untreated string may be nylon.

What is claimed is: 
     
         1 . A method of manufacturing a string for use in a racket, the method comprising:
 (A) preparing an untreated string; and   (B) irradiating the untreated string with radioactive rays.   
     
     
         2 . The method according to  claim 1 , wherein
 the step (B) includes irradiating the untreated string with gamma rays.   
     
     
         3 . The method according to  claim 1 , wherein
 the step (B) includes irradiating the untreated string with the radioactive rays in an irradiation amount of greater than or equal to 250 kGy but less than or equal to 2000 kGy.   
     
     
         4 . The method according to  claim 1 , wherein
 a material of the untreated string prepared in the step (A) is a resin composition whose base material is a thermoplastic resin.   
     
     
         5 . The method according to  claim 4 , wherein
 the thermoplastic resin is polyester or nylon.   
     
     
         6 . A string for use in a racket, wherein
 an elongation rate P1 of the string when the string is tensioned to a stress of 217 MPa is higher than or equal to 9.25% but lower than or equal to 18.6%.   
     
     
         7 . The string according to  claim 6 , wherein
 a material of the string is a resin composition whose base material is a thermoplastic resin, and   the thermoplastic resin is polyester.   
     
     
         8 . A string for use in a racket, wherein
 an elongation rate P2 of the string when the string is tensioned to a stress of 221 MPa is higher than or equal to 19.3% but lower than or equal to 22.0%.   
     
     
         9 . The string according to  claim 8 , wherein
 a material of the string is a resin composition whose base material is a thermoplastic resin, and   the thermoplastic resin is nylon.   
     
     
         10 . A racket comprising a frame and a string, wherein
 an elongation rate P1 of the string when the string is tensioned to a stress of 217 MPa is higher than or equal to 9.25% but lower than or equal to 18.6%.   
     
     
         11 . A racket comprising a frame and a string, wherein
 an elongation rate P2 of the string when the string is tensioned to a stress of 221 MPa is higher than or equal to 19.3% but lower than or equal to 22.0%.