WO2023120441A1

WO2023120441A1 - Ball

Info

Publication number: WO2023120441A1
Application number: PCT/JP2022/046545
Authority: WO
Inventors: 明典浜本; 怜央下石; 弘志村谷; 徹横山; 龍太郎小川; 敏賢國島; 誠竹野下
Original assignee: 株式会社ミカサ
Priority date: 2021-12-22
Filing date: 2022-12-16
Publication date: 2023-06-29

Abstract

Provided is a ball with excellent durability, wear resistance, grip, or control property, and more particularly, a ball suitable for water polo. The ball according to the present invention is a ball that is hot-vulcanized in one piece, having a tube, a fiber-reinforced layer covering the tube, and a surface layer covering the fiber-reinforced layer, wherein the surface layer comprises a foam rubber having a coefficient of static friction from 0.35 to 0.7 and a coefficient of dynamic friction from 0.35 to 0.7. The coefficients of static and dynamic friction herein are based on ball-on-disk friction testing using a sample silicon sphere immersed in water.

Description

ball

The present invention relates to a hand-operated pneumatic ball, and more particularly to a ball suitable for use as a water polo ball.

Volleyball, basketball, handball, and water polo balls are examples of hand-operated pneumatic balls. These balls are required to have cushioning properties, controllability, grip properties, and the like, and balls used in competitions are required to have wear resistance and durability to maintain these properties.

In response to this requirement, Patent Document 1 describes a spherical hollow rubber tube (1) that encloses compressed air, a thread-wound reinforcing layer (2) in which filament threads are uniformly wound on the surface of the rubber tube (1), In a volleyball in which an independent foam sponge layer (3) is attached on the wound reinforcing layer (2) and a leather is adhered to the independent foam sponge layer (3), the wound reinforcing layer (3) is formed when the independent foam sponge layer (3) is formed. A volleyball has been proposed in which an independent foam sponge layer (3) and a thread-wrapped reinforcing layer (2) are integrated by infiltrating an independent foam sponge layer (2). A typical structure of a conventional volleyball is a spherical hollow rubber tube 1 that encloses compressed air. An unvulcanized rubber sheet 6 made of natural rubber, polybutadiene rubber, or the like is adhered on top, and natural leather 4 is applied to the surface of the rubber sheet 6 vulcanized and molded.
Alternatively, the artificial leather 4 is adhered. In contrast to such conventional balls, the ball according to the present invention has ball stability and durability similar to those of conventional balls, and is said to be capable of being further enhanced in shock absorption and repulsive force. .

Patent Document 2 proposes a ball for games such as handball, volleyball, beach volleyball, basketball, etc., which can be easily caught by the finger when grasped and can assist accurate play. That is, a ball comprising a skin formed from a plurality of panels, said skin having a plurality of panel faces, at least one panel face defined by a through joint separating adjacent panel faces. A ball is proposed which is characterized by: It is said that the surface of this ball is preferably made of a porous polyurethane-based resin so that the hand does not slip when gripping the ball.

In Patent Document 3, the compact is made of polyurethane or polyurethane-polyurea foam and has an outer layer composed of a compact skin layer and a layer of microporous regions, the overall thickness of the outer layer being 1.5 to 5 mm, and the compact Sports or leisure balls are proposed in which the skin layer has a thickness of 0.5 to 2 mm. This ball is said to have excellent grip, very little water trapping, a good smooth surface, extremely high abrasion resistance, excellent durability, collision resistance, impact resistance, etc. .

Further, in Patent Document 4, an elastic polymer coating layer is laminated on the surface of a fiber base material, continuous convex portions and discontinuous concave portions are formed on the surface of the coating layer, and the discontinuous concave portions are formed at an average interval of It is formed with a thickness of 0.5 to 3 mm, the depth of the recess is 50 to 500 μm, the vertical projected area of each recess is 1 to 5 mm ² , and the ratio of the total vertical projected area of each recess to the surface area of the coating layer is 3 to 30. A ball for volleyball or beach volleyball made of a sheet-like material characterized by a As the fiber base material of this ball, various fiber base materials such as natural leather, leather-like sheet, woven fabric or non-woven fabric can be used. It is said that vinyl chloride, polyurethane resin, etc. can be used. When the coating layer is made of polyurethane, it is said that the polyurethane can be coagulated into a porous state by immersion in a treatment bath containing a poor solvent.

JP-A-2000-5345 JP 2018-192216 A Patent No. 3173776 JP-A-2008-49147

As shown in Patent Document 1, natural leather or artificial leather is generally used as the material of the skin of a pneumatic ball such as a volleyball that is operated by hand. On the other hand, as shown in Patent Documents 2 to 4, foamed resin or foamed rubber is used as the material of the skin of the ball, and foamed urethane is said to be particularly preferable. However, there is a demand for further improvements in durability, wear resistance, grip and controllability.

In addition, for water polo balls, which are always used in a wet and humid atmosphere, the surface of the ball is buffed to ensure grip and controllability. This processing is performed along the longitudinal direction of each panel surface formed by the grooves that separate the ball surface, and the buff finishing direction is vertical and horizontal when viewed from the entire surface of the ball. Therefore, the ball can be manipulated by gripping different buff finishing direction portions. However, such a ball has the problem that not only is it laborious to process it, but also a large amount of processing waste is discharged.

In view of the demands and problems associated with such conventional hand-operated pneumatic balls, the present invention provides a ball that is excellent in durability, wear resistance, grip and controllability, particularly a ball suitable for water polo. intended to provide

A ball according to the present invention has a tube, a fiber reinforcement layer covering the tube, and a skin layer covering the fiber reinforcement layer, and is integrally thermally vulcanized, wherein the skin layer has static friction. A ball comprising foamed rubber having a coefficient of 0.35-0.7 and a coefficient of dynamic friction of 0.35-0.7. Here, the static friction coefficient and dynamic friction coefficient are based on a ball-on-disk friction test using silicon spheres as samples immersed in water.

In the above invention, the expansion ratio of the foamed rubber is preferably 1.1 to 2.5 times. Here, the expansion ratio (times) is the expansion ratio=specific gravity of unfoamed rubber/specific gravity of foamed rubber.

In addition, the surface roughness of the skin layer should be Ra = 5 to 30 μm.

A ball according to the present invention includes a tube, a fiber reinforcing layer covering the tube, and a skin layer covering the fiber reinforcing layer, and is integrally thermally vulcanized, wherein the skin layer is , a ball made of foamed rubber having an expansion ratio of 1.1 to 2.5 times. Here, the expansion ratio (times) is expansion ratio=specific gravity of unfoamed rubber/specific gravity of foamed rubber.

A ball according to the present invention includes a tube, a fiber reinforcing layer covering the tube, and a skin layer covering the fiber reinforcing layer, and is integrally thermally vulcanized, wherein the skin layer is , a ball made of foamed rubber having a rubber hardness of ASKER C 55-65. Here, the rubber hardness is based on spring type Asker C type (SRIS 0101).

The ball according to the present invention is a hand-operated pneumatic ball and is excellent in durability, wear resistance, grip and controllability. The present invention is particularly suitable for water polo balls.

1 is a schematic diagram of a partial cross section showing the configuration of a ball according to the present invention; FIG. 1 is a schematic diagram showing the front of a conventional water polo ball; FIG. FIG. 4 is a schematic diagram showing a partial cross section of a conventional water polo ball. 1. It is a graph which shows the result of the friction and wear test of the test piece cut out from the part which forms the skin layer of FIG.

A mode for carrying out the present invention will be described below based on the drawings. A ball according to the present invention has a tube, a fiber reinforcing layer covering the tube, and a skin layer covering the fiber reinforcing layer, and is integrally thermally vulcanized. That is, as shown in FIG. 1, the ball 10 has a tube 15, a fiber reinforcement layer 13, and a skin layer 11, and has a known structure, which are integrally molded by heat vulcanization. The material of the skin layer 11 is characterized in that it is foamed rubber having a predetermined coefficient of friction in water. That is, the skin layer 11 has a static friction coefficient of 0.35 to 0.7 and a dynamic friction coefficient of 0.35 to 0.7 based on a ball-on-disk friction test using silicon balls of samples immersed in water.

The material of the skin layer 11 can be natural rubber, butyl rubber, or a mixture of these rubbers, etc., and is subjected to a foaming treatment during heat vulcanization to have independent fine cells 11b. When thermal vulcanization is performed in a mold, the surface 11a of the skin layer 11 can be made to have a predetermined surface roughness by providing unevenness on the mold surface. The surface roughness is preferably Ra=5-30 μm.

The tube 15 and the fiber reinforcement layer 13 of the ball according to the present invention can be made of known materials and configurations. The thickness of each member constituting the ball according to the present invention is, for example, tube 15: 0.7 to 1.2 (mm), fiber reinforcement layer 13: 0.7 to 1.1 (mm), skin layer 11: 1.1 to 2.0 (mm). can do.

On the other hand, Fig. 2 shows a water polo ball as a conventional ball. The ball 10 has a ball surface covered with a plurality of panels 10a separated by grooves 10b, each panel being buffed to have a striped groove 10c in the longitudinal direction of the panel. When viewed from the ball as a whole, the grooves 10c are arranged lengthwise and crosswise on the ball.

Fig. 3 shows the configuration of this conventional water polo ball. As shown in FIG. 3, ball 10 includes tube 15, fiber reinforcement layer 13 and skin layer 11. As shown in FIG. The surface 11a of the skin layer 11 has considerably larger irregularities than the ball 10 according to the present invention shown in FIG. 1, and it was difficult to measure the surface roughness (Ra).

The above surface roughness measurement was performed as follows. First, two specimens of the material forming the skin layer 15 were produced: a foamed test piece (foamed), and two foamed test pieces (foamed + irregularities). Vulcanization was performed at 155°C for 300 seconds, and the expansion ratio was 1.1 to 2.5 times. The test pieces were compounded, stabilized for 24 hours or more, and then vulcanized. After 24 hours or more had passed after vulcanization, the surface roughness was measured.

　The surface roughness was measured using a measuring machine (SJ-500: manufactured by Mitutoyo), and the median value of five random measurements was taken as the surface roughness Ra (JISB0601-2001). The surface roughness was Ra=4.07 for foaming and Ra=7.42 for foaming+unevenness. The surface and cross section of the test piece were observed with a digital microscope (VHX-5000: manufactured by Keyence Corporation).

In addition, the above coefficient of friction was obtained by a friction/wear test. As test pieces, the above test piece (foamed) and test piece (foamed + irregularities) (inventive example) and a test piece (comparative example) made of the same material as the surface layer of the water polo ball were prepared. These test pieces were subjected to a ball-on-disk friction test using silicon balls using a friction and wear tester (HEIDON Type 20, manufactured by Shinto Kagaku Co., Ltd.) modified for this measurement. A load of 500 g was applied to the silicon ball (hardness 50), the rotation speed was 50 rpm×5 rotations, and the measurement was performed 5 times. The maximum value between 0 and 1500 (s) for the measurement time was taken as the static friction coefficient, and the average value between 1500 and 3500 (s) as the dynamic friction coefficient. In addition, before the first test of each sample, one rotation of break-in operation was performed, and the measured values at three points excluding the maximum and minimum values were used as representative values. In the table, "wet" means that the friction/wear test was performed by immersing the test piece in water, and "dry" means that the friction/wear test was performed in the air (dry type). A conventional water polo ball is a water polo ball in which the surface of the ball is buffed.

Table 1 shows the measurement results of the coefficient of friction. In addition, using a water polo ball having the same shape as a conventional water polo ball having the skin layer according to this invention example (invention example) and a conventional water polo ball (comparative example), actual ball operability and grip were examined. A sensory test was conducted to evaluate the properties. In the sensory test, the subjects soaked their hands in water prior to the test and grabbed the ball several times to get used to it. After that, they grasped each ball and turned left and right to evaluate the grip performance of the ball. The evaluation method was relative evaluation with the sensory score of the comparative example being 3.0 and the maximum sensory score being 5.0. Table 2 shows the results of the sensory test.

FIG. 4 shows the results of evaluating the operability and grip of a water polo ball having the skin layer 15 according to the present invention. The horizontal axis indicates the coefficient of friction, and the vertical axis indicates the value obtained by dividing the total sensory score by 24 (sensory score/24). According to FIG. 4, both the static friction coefficient curve and the dynamic friction coefficient curve have similar shapes. Both friction coefficient curves have a substantially proportional relationship between the friction coefficient and the sensory score when the friction coefficient is between 0.35 and 0.4 or about 0.45. However, it can be seen that the coefficient of friction curve shows that when the coefficient of friction exceeds 0.4 or 0.45, the rate of increase in the sensory score with respect to the coefficient of friction gradually decreases, and becomes almost horizontal (saturated) at a coefficient of friction of about 0.7. That is, the balls of invention examples (balls such as water polo balls in a state of moisture/humidity) have higher dynamic friction coefficients and static friction coefficients (friction coefficients) than conventional water polo balls, and the friction coefficients are 0.35 to 0.4 or It is understood that the ball of the invention example of 0.45 has about 20% improvement in operability and grip. The starting point of the coefficient of friction curve is the sensory score of the conventional water polo ball/24=1.

Further, in the ball according to the present invention, when the coefficient of friction exceeds 0.4 or 0.45, the operability and grip performance do not increase as much as the increase rate of the coefficient of friction. It is understood that the stamina and grip properties are not improved and reach a saturation point.

Table 3 shows the results of the rubber hardness test of the skin layer 11 of the ball according to the present invention. Rubber hardness is ASKER C hardness by spring type Asker C type (SRIS 0101). In Table 3, the average value indicates the ratio (%) of the average rubber hardness of the inventive examples to the rubber hardness of the comparative examples. Inventive examples are the above-mentioned test pieces (foaming + unevenness), and comparative examples are test pieces (comparative example) made of the same material as the surface layer of the water polo ball. According to Table 3, the hardness of the inventive examples is about 80% of that of the comparative examples, and they are more flexible. In addition, the minimum rubber hardness of the invention examples is 55, and the maximum rubber hardness is 65.

10 ball 11 tube 13 fiber reinforcement layer 15 skin layer

Claims

A ball comprising a tube, a fiber reinforcing layer covering the tube, and a skin layer covering the fiber reinforcing layer, and integrally thermally vulcanized,
A ball in which the skin layer comprises foamed rubber having a static friction coefficient of 0.35-0.7 and a dynamic friction coefficient of 0.35-0.7.
Here, the static friction coefficient and dynamic friction coefficient are based on a ball-on-disk friction test using silicon spheres as samples immersed in water.
2. The ball according to claim 1, wherein the foamed rubber has an expansion ratio of 1.1 to 2.5 times.
Here, the expansion ratio (times) is expansion ratio=specific gravity of unfoamed rubber/specific gravity of foamed rubber.
The ball according to claim 1 or 2, wherein the surface roughness of the skin layer is Ra = 5 to 30 µm.
A ball comprising a tube, a fiber reinforcing layer covering the tube, and a skin layer covering the fiber reinforcing layer, and integrally thermally vulcanized,
The ball, wherein the skin layer comprises foamed rubber having an expansion ratio of 1.1 to 2.5 times.
Here, the expansion ratio (times) is expansion ratio=specific gravity of unfoamed rubber/specific gravity of foamed rubber.
A ball comprising a tube, a fiber reinforcing layer covering the tube, and a skin layer covering the fiber reinforcing layer, and integrally thermally vulcanized,
A ball in which the skin layer comprises foamed rubber having a rubber hardness of ASKER C 55-65.
Here, the rubber hardness is based on the spring type Asker C type (SRIS 0101).
The ball according to claim 1, 4 or 5, which is for water polo.