String for a racket, particularly for a tennis racket

Abstract

The invention relates to a string for a racket, particularly for a tennis racket, which includes: a central core ( 2 ) and a peripheral protective layer ( 6 ). Additionally, the string includes an intermediate reinforcing layer ( 4 ) made of a composite material and placed between the central core ( 2 ) and the peripheral protective layer ( 6 ), the hardness of the reinforcing layer ( 4; 14; 24; 34 ) being greater than the hardness of the protective layer ( 6; 16; 26; 36 ), the reinforcing layer providing a function of increasing the resistance to wear and tear, while the protective layer provides a function of increasing sliding.

1 - 20 . (canceled) 
     
     
         21 . A string for a racket, in particular for a tennis racket, comprising:
 a central core, and   a peripheral protective layer,   wherein the string comprises, in addition, an intermediate reinforcing layer made of a composite material, positioned between the central core and the peripheral protective layer, the hardness of the reinforcing layer being greater than the hardness of the protective layer, the reinforcing layer carrying out a role of increasing the wear resistance, whereas the protective layer carries out a role of increasing slip.   
     
     
         22 . A string according to claim  1 , wherein the intermediate reinforcing layer is a composite sheath. 
     
     
         23 . A string according to claim  1 , wherein the intermediate reinforcing layer comprises a matrix and reinforcing fillers, the fillers representing between 10% and 60% by weight of the reinforcing layer, preferably between 25% and 35%. 
     
     
         24 . A string according to  claim 23 , wherein the fillers are glass beads. 
     
     
         25 . A string according to  claim 24 , wherein the glass beads have a largest dimension, in particular a diameter, between 1 μm and 50 μm, preferably between 5 μm and 20 μm. 
     
     
         26 . A string according to  claim 23 , wherein the fillers are carbon fibers or ceramic particles. 
     
     
         27 . A string according to  claim 23 , wherein the matrix comprises polyamide. 
     
     
         28 . A string according to  claim 21 , wherein the central core is constituted of a monofilament. 
     
     
         29 . A string according to  claim 21 , wherein the central core comprises multi-filaments positioned in a binding material. 
     
     
         30 . A string according to  claim 21 , wherein the central core comprises at least three helically twisted yarns. 
     
     
         31 . A string according to  claim 21 , wherein the central core comprises a central filament of diameter d 2  around which filaments of diameter d 3  are positioned helically, so that d 2  is greater than d 3 . 
     
     
         32 . A string according to  claim 21 , wherein the central core is composed of polyamide. 
     
     
         33 . A string according to  claim 21 , wherein the peripheral protective layer comprises a base polymer, and also at least one additive intended to increase slip. 
     
     
         34 . A string according to  claim 33 , wherein the base polymer is a plastic, in particular polyamide, polyurethane, polyester or polypropylene, whereas the slip additive is silicone or PTFE. 
     
     
         35 . A string according to  claim 33 , wherein the slip additive is present, in the peripheral protective layer, between 10% and 60% by weight, preferably between 25% and 35%. 
     
     
         36 . A string according to  claim 21 , wherein the central core has a diameter d 4  between 0.5 mm and 1.5 mm. 
     
     
         37 . A string according to  claim 21 , wherein the reinforcing layer has a radial thickness e 1  between 0.01 mm and 0.5 mm. 
     
     
         38 . A string according to  claim 21 , wherein the peripheral protective layer has a radial thickness e 2  between 0.01 mm and 0.5 mm. 
     
     
         39 . A string according to  claim 21 , wherein the reinforcing layer is extruded around the central core. 
     
     
         40 . A string according to  claim 21 , wherein the protective layer is extruded around the reinforcing layer.