Patent ID: 7648434

Claim:
A ball for a ball game comprising a bladder made of rubber or elastomer and a foamed layer covering an outer surface of the bladder, wherein an outer surface of the foamed layer is divided by linear partitions, the outer surface of the foamed layer comprises the partitions and sectionalized surfaces, comprising a remainder of the outer surface of the foamed layer, the partitions are raised relative to the sectionalized surfaces adjacent to the partitions, a tip of the raised partition is in contact with outer air, a skin layer is provided on the sectionalized surfaces, the foam layer comprises vulcanized rubber and foamed cells, the foamed layer further comprises: a raised portion A of a first spherical surface, which includes the tip of the raised partition and is concentric to the ball for a ball game, and a second spherical surface, which includes a peripheral portion of the sectionalized surfaces adjacent to the partitions and is concentric to the ball for a ball game; and a portion B of the foamed layer, which comprises a remainder of the foamed layer, a number of foamed cells in the portion A is 100-1,000 per cm 2 , and the number of foamed cells in the foamed layer gradually decreases as a distance from beneath the partition, toward the portion A, increases, a diameter of foamed cells in the portion B is 75-400 micrometers, and a number of foamed cells in the portion B is 1,000-10,000 per cm 2 .