Sumitomo Rubber Industries Limited

Fumiya Suzuki

Kazuyoshi Shiga

Hiroaki Tanaka

Kunio Niwa

Takehiko Hyodo

Masanori Taguchi

Kohei Mimura

Yosuke Yamamoto

Yuko Sakurai

An aqueous adhesive for rubber includes rubber latex and an ammonium-salt-based vulcanization acceleration aid. An amount of the ammonium-salt-based vulcanization acceleration aid contained in the aqueous adhesive is preferably not less than 0.01% by weight and not greater than 5.0% by weight in terms of solid content. An aqueous adhesive for a ball includes rubber latex as a main component. A content of an inorganic filler in the aqueous adhesive is not greater than 0.1% by weight in terms of solid content. A ballincludes a hollow coreobtained by crosslinking a rubber composition that contains a vulcanizing agent. The coreis formed of two hemispherical half cores. The two half cores are adhered to each other by using the aqueous adhesive for a ball.

Aqueous adhesive for rubber and aqueous adhesive for ball

A rubber composition for a hollow ball includes a base rubber and an inorganic filler. A weight reduction rate TGAfrom room temperature to 650&#xb0; C. and a weight reduction rate TGAfrom room temperature to 850&#xb0; C. of the rubber composition are measured under an air atmosphere by thermogravimetry conforming to JIS K0129. The weight reduction rate TGAof the rubber composition is not less than 63% and not greater than 99%. A difference (TGA&#x2212;TGA) between the weight reduction rates TGAand TGAof the rubber composition is not less than 0% and not greater than 7%. A hollow ballincludes a hollow coreformed from the rubber composition.

Rubber composition for hollow ball and hollow ball

A rubber composition for a tennis ball includes a base rubber and a filler having a degree of flatness DL of not less than 50, the degree of flatness DL being obtained by dividing an average particle diameter D(&#x3bc;m) of the filler by an average thickness T (&#x3bc;m) of the filler. An amount of the filler per 100 parts by weight of the base rubber is not less than 1 part by weight and not greater than 150 parts by weight. A gas permeability coefficient GPS and a loss tangent tan &#x3b4;S of the rubber composition and a gas permeability coefficient GPL and a loss tangent tan &#x3b4;L of a rubber composition obtained by replacing the filler with kaolin clay having a degree of flatness DL of 20 satisfy (1): GPL/GPS&#x2265;1.02 and (2): |tan &#x3b4;L&#x2212;tan &#x3b4;S|&#x2264;0.03. A tennis ballincludes a coreformed using the rubber composition.

Rubber composition for tennis ball and tennis ball

A rubber composition for a tennis ball includes a base rubber and a high-flatness filler. The high-flatness filler has an average particle diameter Dof not less than 1 &#x3bc;m and not greater than 50 &#x3bc;m. A degree of flatness DL is not less than 40 and not greater than 200. An amount of the high-flatness filler per 100 parts by weight of the base rubber is not less than 5 parts by weight and not greater than 100 parts by weight. A ratio (E2/E1) of a tensile elastic modulus E2 in a tensile strain range from 70% to 100% to a tensile elastic modulus E1 in a tensile strain range from 10% to 30%, of a vulcanized rubber obtained by vulcanizing the rubber composition, is not less than 0.60 and less than 1.00. The tennis ball includes a hollow core formed from the rubber composition.

Rubber composition for tennis ball

A rubber composition for a hollow ball includes a base rubber, an inorganic filler composed of a large number of flat particles, and a carbon-based filler. As to the carbon-based filler, a degree of flatness DLc obtained by dividing an average particle diameter D(&#x3bc;m) by an average thickness Tc (&#x3bc;m) is not less than 50. A weight ratio Mc/Mi is not less than 0.01 and not greater than 1.00. The rubber composition is obtained by a production method including: a first step of mixing the base rubber and the carbon-based filler to obtain a master batch; and a second step of adding the large number of flat particles that form the inorganic filler, to the master batch to orient the large number of flat particles. The hollow ballincludes a coreformed from the rubber composition.

In a tennis racket, longitudinal strings extending in a longitudinal direction and transverse strings extending in a transverse direction intersect each other to form a plurality of meshes. At a center, in the transverse direction, of a head, a ratio of an area St of a tip mesh located closest to a tip in the longitudinal direction relative to an area Sc of a center mesh located at a center in the longitudinal direction is not less than. The center mesh is formed in a rectangular shape having short sides in the longitudinal direction and long sides in the transverse direction. Preferably, from the center mesh to the tip mesh, an area of each mesh is set so as to be not larger than an area of a mesh adjacent thereto at a tip side.

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Kobe, Japan

Fumiya Suzuki