To provide a gas-filled sport ball which has sufficient mechanical strength, such as outstanding nonslip characteristics and skin frictional strength, and can be suitably used especially in the field of material of balls, such as basketball, American football, Rugby ball or the like.
A sheet has a covering layer having substantially continuous projections and hemispherical recesses adjoining them formed on the surface of a fibrous substrate. Difference in height of the projections and the recesses is 50-1,000 m, the vertical projected area of the adjoining recess is 3-30 mm2, the average space between the recesses are 0.5-3 mm. Furthermore, the surface of the sheet is formed with the secondary irregularity having a depth smaller than the depth of the recesses and within the range of 10-100 m. Balls for basketball, handball, Rugby ball or American football is made of the sheet.
| JP3178734 | Ball for ball games |
| JPS62189081 | BALL FOR BALL GAME |
YASUDA YOSHIAKI
ASHIDA TETSUYA
| JP2005087315A | 2005-04-07 |
| US4570931A | 1986-02-18 | |||
| WO2005097269A1 | 2005-10-20 |
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