A device including a deformable shell delimiting an inner space, and a resilient band suspended in the inner space and including two ends secured to the deformable shell. The band includes a piezoelectric material to generate an electric voltage under the effect of the deformation of the shell and two electrodes for collecting the voltage. An electronic circuit for processing the voltage is arranged on the resilient band and connected to the electrodes of the resilient band.

In some aspects, the invention relates to a inflation independent sports ball comprising a foam core 15 and an outer covering 10, wherein the sports ball is selected from the group consisting of a football, a basketball, a volleyball and a soccer ball, wherein the sports ball 5 is devoid of an inflatable air bladder. In other aspects, the invention relates to a sports ball having a diameter and comprising a synthetic leather outer covering 10 at least partially covering a polyurethane foam core 15, wherein the foam core further comprises at least one internal compartment and a cylindrical body spanning at least part of the length of the diameter of the sports ball. In other aspects, the invention relates to a sports ball having an outer covering and a foam core, wherein the foam core 15 is not filled with foam entirely throughout its internal volume, but rather includes space for air.

An object of the present invention is to provide a rubber composition from which a crosslinked rubber molded product excellent in the resilience performance can be obtained. The present invention provides a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, wherein (b) the co-crosslinking agent contains a complex represented by a general formula (1). ##STR00001## [In the formula (1), M is a metal atom, and L is a carboxylate represented by the general formula (2). In the formula (2), R is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms or an alkynyl group having 2 to 18 carbon atoms, and the dotted line shows a resonance structure. In the formula (1), a plurality of R may be identical to or different from each other, and at least one of R is the alkenyl group having 2 to 18 carbon atoms or the alkynyl group having 2 to 18 carbon atoms.]

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.sub.50.sup.c (m) by an average thickness Tc (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 ball 2 includes a core 4 formed from the rubber composition.

A method of making a throwable paintball is provided. The method includes providing a first solution of sodium alginate and water; a second solution of water, glycerin, cornstarch, calcium chloride and dye; introducing the second solution into the first solution, forming the paintball; rinsing the paintball; heating the paintballs and storing the paintball in a glycerin and water solution. A throwable paintball manufactured according to the method is also provided.

The aqueous adhesive for a tennis ball includes rubber latex. The rubber latex is a mixture of liquid rubber latex and solid rubber latex. When a solid content in the aqueous adhesive is measured at a temperature of 140? C. by a curelastometer, a torque is not less than 0.26 N.Math.m after 10 minutes from start of heating. The tennis ball includes a seam portion formed of the aqueous adhesive for a tennis ball.

An apparatus having a control circuit including a computer processor and a computer memory configured with computer software. The control circuit causes a first test assembly to conduct an initial test of the air pressure within an inner chamber of a first tennis ball; and if the control circuit determines that the air pressure is below a threshold, a pressurization process increases the air pressure inside the inner chamber of the first tennis ball by piercing the outer skin of the first tennis ball with a needle, until a tip of the needle is in the inner chamber, and a first opening, plugged by the needle, is formed in the outer skin of the first tennis ball. The needle tip is thereafter withdrawn from the inner chamber of the first tennis ball, leaving the first opening unplugged and sealant is applied to the first opening to close the first opening.

A tennis ball may include a spherical hollow core having an inner surface including material shift lines and a textile outer layer over and about the core.

A sports ball, for example a soccer ball, comprising a hollow shell and a pit suspended within the hollow shell by a plurality of cords. In some embodiments, the plurality of cords may comprise a first end coupled to the hollow shell at a first location, a second end coupled to the hollow shell at a second location, and a center portion coupled to the pit. In some embodiments, the pit may be suspended within the hollow shell by a plurality of cords, with each of the plurality of cords comprising a frayed end secured to the hollow shell at one of a plurality of spaced apart locations.

An object of the present invention is to provide a rubber composition from which a crosslinked rubber molded product excellent in the resilience performance can be obtained. The present invention provides a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, wherein (b) the co-crosslinking agent contains a complex represented by a general formula (1).

##STR00001##

[In the formula (1), M is a metal atom, and L is a carboxylate represented by the general formula (2). In the formula (2), R is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms or an alkynyl group having 2 to 18 carbon atoms, and the dotted line shows a resonance structure. In the formula (1), a plurality of R may be identical to or different from each other, and at least one of R is the alkenyl group having 2 to 18 carbon atoms or the alkynyl group having 2 to 18 carbon atoms.]