Tennis racket string

• US 4,183,200 A
• Filed: 10/03/1977
• Issued: 01/15/1980
• Est. Priority Date: 10/03/1977
• Status: Expired due to Term

• Current Assignee: Wilson Sporting Goods Company (Anta International Group Holdings Ltd.)
• Original Assignee: PepsiCo Incorporated
• Inventors: Bajaj, Girdhar
• Primary Examiner(s): Watkins, Donald
• Application Number:
  US05/838,669
• Time in Patent Office: 834 Days
• Field of Search: 57/140 R, 57/144, 57/149, 57/150, 57/153, 57/154, 57/210, 57/225, 57/232, 57/234, 57/235, 428/377, 428/380, 428/389
• US Class Current: 57/234
• CPC Class Codes: A63B 51/02 Strings; String substitutes; Products applied on strings, e.g. for protection against humidity or wear

Abstract

A string for a tennis racket composed of a synthetic resin such as nylon and having a combination of properties which provides a highly desirable balance between playability and durability. Specifically, the string has a spring rate of from 45 to 65 pounds/inch (8.0 to 11.6 kg/cm) at a loading in the range of 50 to 100 pounds (22.7 to 45.4 kg), the string exhibiting a substantially linear stress-strain behavior in the foregoing range, a minimum tensile break load of 120 pounds (54.4 kg), a thickness of from 0.040 to 0.055 inch (0.10 to 0.14 cm), a minimum overhand knot strength of 50 pounds (22.7 kg), and a minimum surface friction of 0.120.

Claims

1. A tennis racket string comprising a solid mono-filamentary core having strands wound thereabout and adhesively secured thereto without degradation of the strands, both said core and said strands being composed of a synthetic resin, said core having a thickness of three to six times the thickness of the strand, said string having a spring rate of from 45 to 65 pounds/inch (8.0 to 11.6 kg/cm) at a loading in the range of 50 to 100 pounds (22.7 to 45.4 kg), said string exhibiting a substantially linear stress-strain behavior in said range, a minimum tensile break load of 120 pounds (54.4 kg), a total thickness of from 0.040 to 0.055 inch (0.102 to 0.140 cm), a minimum overhand knot strength of 50 pounds (22.7 kg), and said strands being encased by a separate continuous, smooth outer resin layer composed solely of a set resin adhesive bonded to the string thereby providing said string with an improved surface texture.

2. A tennis racket string according to claim 1 in which said synthetic resin is nylon.

3. A tennis racket string according to claim 1 which has a damping capacity of 0.470 to 0.750.

4. A tennis racket string according to claim 1 which has a 180°

bend fatigue value of at least 5 minutes.

5. A tennis racket string according to claim 1 which has a double loop strength of at least 90% of its minimum knot strength.

6. A tennis racket string according to claim 1 which has a uniform thickness of from 0.045 to 0.0530 inch (0.114 to 0.135 cm).

7. A tennis racket string according to claim 1 which has a minimum break load of 135 pounds (61.2 kg).

8. A tennis racket string according to claim 1 which has a minimum knot strength of 70 pounds (31.8 kg).

9. A tennis racket string according to claim 1 which has a surface friction of from 0.150 to 0.400.

10. A tennis racket string comprising a solid core of nylon mono-filament and nylon strands of substantially less thickness wound about said core and adhesively secured thereto without degradation of the strands, said string having a spring rate of 45 to 65 pounds/inch (51.8 to 74.9 kg/cm) at a loading in the range from 50 to 100 pounds (22.7 to 45.4 kg) and exhibiting a substantially linear stress-strain behavior in said range, a total thickness of from 0.045 to 0.0530 inch (0.114 to 0.135 cm), a minimum break load of 135 pounds (61.2 kg), a minimum knot strength of 70 pounds (31.8 kg), and said strands being encased by a separate, continuous, smooth outer resin layer composed solely of a set resin adhesive bonded to the string, thereby providing said string with an improved surface texture.