Billiard rubber

Abstract

Provided is a novel technique for billiard rubber, which makes it easier to play a spin ball and can provide a higher ball hitting speed. A billiard rubber comprises: a spongy sheet; and a rubber sheet laminated and adhered to the sponge-like sheet, the rubber sheet having a plurality of protrusions formed on an adhesive surface of a main body of the rubber sheet and the sponge-like sheet, in which the rubber sheet has a thickness of 1.6 mm or less in a lamination direction of the sponge-like sheet, and ar / h is 52 or more, where ar represents a value of an area percentage (%) of the protrusions to the adhesive surface, and h represents a value of an area percentage (%) of the protrusions to the adhesive surface. And h represents the value of the height (mm) of the protrusion.

Description

Technical Field

[0001] The present invention relates to a table tennis rubber for table tennis used when adhered to a main body of a table tennis racket. Background Art

[0002] Typically, a billiard rubber is composed of a sponge-like sheet and a rubber sheet adhered to the sponge-like sheet. In a billiard racket, the billiard rubber accounts for a large part of its hitting performance.

[0003] Specifically, for example, table tennis rubber is required to have improved speed performance (performance that provides a higher hitting speed) and spin performance (performance that allows a player to easily hit a spinning ball).

[0004] Therefore, in order to improve these properties, various rubbers different in constituent members, surface shapes, etc. have been proposed, and so-called reverse rubber is known as one of them.

[0005] The anti-rubber is composed of a sponge sheet and a rubber sheet laminated on the sponge sheet, and a plurality of protrusions are formed on the bonding surface of the rubber sheet and the sponge sheet. The anti-rubber obtains increased spin performance by providing a flat hitting surface with an increased ball contact area, and reduces the compression stiffness of the entire rubber by the protrusions biting into the sponge sheet, thereby providing a longer ball contact time, thereby obtaining increased ball control performance (performance that allows the player to more reliably hit the ball in the desired direction).

[0006] On the other hand, inverted rubber tends to cause energy loss in the ball because the protrusions bite into the spongy sheet when the ball is hit, reducing its elasticity. This energy loss causes the ball to slow down and therefore be unpredictable.

[0007] In view of this, it has been proposed to improve the billiard rubber in terms of speed performance by adjusting the polymer properties as a material. For example, a billiard rubber having enhanced spin performance by mixing chemicals with good elastic properties or by mixing a viscous substance in a rubber sheet has been previously proposed.

[0008] Furthermore, a billiard ball rubber having improved speed performance by changing the shape of protrusions in a rubber sheet has been previously proposed.

[0009] The applicant also submitted an application for a table tennis rubber comprising: a sponge-like sheet; and a rubber sheet, which is stacked and adhered to the sponge-like sheet, and has a plurality of protrusions formed on a bonding surface of a main body of the rubber sheet with the sponge-like sheet (Patent Documents 1, 2).

[0010] Reference List

[0011] Patent Literature

[0012] Patent Document 1: JP2013-17651

[0013] Patent Document 2: JP2021-45449 Summary of the invention

[0014] Technical issues

[0015] The object of the present invention is to provide a new technology for table tennis rubber, which makes it easier to hit the ball with spin and can provide a higher hitting speed.

[0016] Solution to the problem

[0017] From the perspective of freedom in product design, additional options are needed for technologies that improve speed performance, rotational performance, etc.

[0018] The inventors have diligently studied and found that improved speed performance and rotation performance are achieved by a configuration in which the thickness of the rubber sheet and a value calculated by dividing the area percentage of the protrusion relative to the bonding surface by the height of the protrusion are both within specific ranges, thereby completing the present invention.

[0019] A summary of the present invention is as follows.

[0020] [1] A table tennis rubber comprising:

[0021] Sponge-like sheets; and

[0022] a rubber sheet which is laminated and adhered to a sponge-like sheet, the rubber sheet having a plurality of protrusions formed on a bonding surface of a main body of the rubber sheet with the sponge-like sheet,

[0023] wherein the rubber sheet has a thickness of 1.6 mm or less in the lamination direction of the sponge-like sheets, and

[0024] ar / h is 52 or more, wherein ar represents the value of the area percentage (%) of the protrusion with respect to the bonding surface, and h represents the value of the height (mm) of the protrusion.

[0025] [2] The table tennis rubber according to [1], wherein ar / h is 55 or more.

[0026] [3] The table tennis rubber according to [1], wherein ar / h is 60 or more.

[0027] [4] The table tennis ball rubber according to any one of [1] to [3], wherein the protrusion has a height of 0.7 mm or less.

[0028] [5] The table tennis rubber according to any one of [1] to [4], wherein the rubber sheet has a thickness of 1.5 mm or less in the stacking direction of the sponge-like sheets.

[0029] [6] The table tennis rubber according to [5], wherein the rubber sheet has a thickness of 1.4 mm or less in the stacking direction of the sponge-like sheets.

[0030] [7] A table tennis racket, wherein the table tennis rubber according to any one of [1] to [6] is adhered to a main body of the racket.

[0031] Advantageous Effects of the Invention

[0032] The invention can provide a new technology of table tennis rubber, which makes it easier to hit a spinning ball and can provide a higher hitting speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [ Figure 1 ] Figure 1 It is a perspective view of a table tennis racket to which the table tennis rubber according to an embodiment of the present invention is adhered.

[0034] [ Figure 2 ] Figure 2 It is a cross-sectional view of the table tennis rubber according to an embodiment of the present invention in the stacking direction.

[0035] [ Figure 3 ] Figure 3 It is a cross-sectional view of a rubber sheet in a table tennis rubber according to an embodiment of the present invention in a stacking direction. DETAILED DESCRIPTION

[0036] An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0037] Figure 1 FIG. 1 is a perspective view of a table tennis racket 100 according to the present embodiment. Figure 1 As shown, the table tennis racket 100 includes a racket plate 10 (a main body of the table tennis racket) and a table tennis rubber 20 adhered to the racket plate 10 .

[0038] The racket blade 10 is made of wood, and the handle 14 is fixed to the portion of the racket blade to be held in use by an adhesive. Although a horizontal grip racket blade for double-sided hitting is shown in the drawings, the shape of the racket blade in this embodiment is not limited thereto, and the racket blade may be a penhold grip type.

[0039] Figure 2 2 is a cross-sectional view of the table tennis rubber 20 of the present embodiment in the stacking direction. The table tennis rubber 20 of the present embodiment is a so-called reverse rubber, and in this configuration includes a sponge sheet 22 and a rubber sheet 24. The sponge sheet 22 and the rubber sheet 24 are stacked and adhered to each other to form a whole. A plurality of protrusions 26 are formed on the bonding surface of the rubber sheet 24 with the sponge sheet 22 at specific intervals.

[0040] Each protrusion 26 has a generally cylindrical shape, with a vertex 261, which is visible in a generally circular shape in a front view (hereinafter, also referred to as a "front view") from the bonding surface of the sponge-like sheet 22. The vertex 261 of the protrusion faces and contacts the sponge-like sheet 22, and the rubber sheet 24 is joined to the sponge-like sheet at the vertex 261 of the protrusion. Therefore, the vertex 261 serves as the contact surface of the protrusion 26 with the sponge-like sheet 22. The technical manual of the International Table Tennis Federation stipulates that "the rubber particles must be evenly spaced 60 degrees from each other along three sets of parallel lines". In addition, in the table tennis rubber of this embodiment, the protrusions 26 can be evenly distributed on the bonding surface in the same arrangement as described in the specification.

[0041] Here, the region of the rubber sheet 24 other than the protrusions 26 is referred to as a rubber sheet main body 23 .

[0042] The surface 33 of the table tennis rubber 20 on the sponge-like sheet 22 side is bonded to the racket body 10. The surface 35 on the rubber sheet 24 side is used as a hitting surface for the ball.

[0043] The overall shape of each protrusion 26 is not limited, and may be the above-mentioned substantially cylindrical shape, or any other shape, such as a substantially truncated cone, a shape in which a substantially truncated cone vertex and a substantially cylindrical shape are combined and integrated together, and a shape in which a substantially cylindrical vertex and a substantially truncated cone are combined and integrated together. The shape of the vertex of each protrusion is not limited, and may be a circle or a polygon, such as a triangle and a rectangle.

[0044] The sponge-like sheet 22 uses a polymer, examples of which include, but are not limited to, common natural rubber, polyisoprene, polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene-diene copolymer, ethylene-propylene copolymer, polychloroprene, isobutylene-isoprene copolymer, styrene-based thermoplastic elastomer and olefin-based thermoplastic elastomer. In particular, it is preferred to use natural rubber, butadiene rubber, isoprene rubber, etc. for production, and those skilled in the art can even appropriately select chemicals to be mixed. The sponge-like sheet can have any characteristics without limitation, and, for example, density, hardness and foam size can be 0.1 to 0.7 g / cm, respectively. 3 , 10 to 70 (measured with "ASKER Rubber Hardness Tester Type E" manufactured by Kobunsu Keiki Co., Ltd.), and 0.03 to 0.50 mm. In order to calculate the density of the sponge-like sheet 22, for example, the weight and volume are measured, and the measured weight is divided by the volume. The hardness of the sponge-like sheet 22 can be measured, for example, according to standard number JIS K6253.

[0045] Similarly, the rubber sheet 24 uses a polymer, examples of which include, but are not limited to, common natural rubber, polyisoprene, polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene-diene copolymer, ethylene-propylene copolymer, polychloroprene, isobutylene-isoprene copolymer, styrene-based thermoplastic elastomer, and olefin-based thermoplastic elastomer. In particular, it is preferred to use natural rubber, butadiene rubber, isoprene rubber, etc. for production, and those skilled in the art can even appropriately select the chemicals to be mixed. The rubber sheet 24 can have any properties without limitation, for example, the density and hardness can be 0.6 to 3.0 g / cm, respectively. 3 and 20 to 65.

[0046] In order to calculate the density of the rubber sheet 24 , for example, the weight is measured using an “Excellence XS analytical balance” manufactured by METTLER TOLEDO, and the measured weight is divided by the volume.

[0047] In order to obtain the hardness value of the rubber sheet 24, for example, the rubber sheet is measured with a "microhardness tester MD-1 Type A" manufactured by Kobunshi Keiki Co., Ltd. This hardness tester has a cantilever leaf spring for loading, and is capable of expressing the hardness as a point from 0 to 100. The spring load at the 0 point corresponds to 22 mN, the pressure at the 100 point corresponds to 332 mN, and the pressure head has a cylindrical shape with a diameter of 0.16 mm and a height of 0.5 mm. The hardness range of 20 to 65 shown as an example in this embodiment can also be expressed as a range of spring loads of, for example, 84.4 mN to 224.8 mN.

[0048] Figure 3 Yes means Figure 2 FIG. 1 is a diagram of an area surrounded by a dotted line m of the rubber sheet 24 of the table tennis rubber 20 of the present embodiment.

[0049] Here, the thickness T of the rubber sheet 24 on the sponge-like sheet 22 in the stacking direction (hereinafter, also referred to as thickness T or T) is 1.6 mm or less. In order to improve the speed performance and the rotation performance, the thickness T is preferably 1.5 mm or less, and more preferably 1.4 mm or less. The thickness T can also be calculated based on the thickness of the rubber sheet main body 23 in the stacking direction and the height of the protrusion described later.

[0050] In this embodiment, ar / h is greater than 52, where ar represents the value of the area percentage (%) of the protrusion to the bonding surface (hereinafter also referred to as the area percentage ar or simply ar), and h represents the value of the height (mm) of the protrusion, hereinafter also referred to as the height h or h of the protrusion.

[0051] Here, the area percentage of the protrusion relative to the bonding surface refers to the ratio of the area per unit area of ​​the portion of the protrusion 26 of the rubber sheet 24 that contacts the sponge-like sheet 22. The area percentage ar can be determined by calculation. For example, in the case where the vertex of each protrusion has a round shape, the following formula can be used for calculation.

[0052] ar=(A / 2) 2 ×π×100 / ((A+B) 2 ×sin(π / 3))

[0053] ar: Area percentage of protrusion 26 to bonding surface (%)

[0054] A: Diameter of the portion of the protrusion 26 that contacts the sponge-like sheet (apex 261) (mm)

[0055] B: distance between two adjacent protrusions 26 (mm)

[0056] As described above, the configuration in which the thickness T is 1.6 mm or less and ar / h is 52 or more provides improved speed performance and rotation performance.

[0057] The value of ar / h is preferably 55 or more, more preferably 60 or more, because further improved speed performance and rotation performance can be achieved.

[0058] The value of ar / h is not limited thereto, but is preferably 130 or less.

[0059] The thickness T is similarly not limited thereto, but is preferably 0.6 mm or more.

[0060] The height h of the protrusion is not limited thereto, but is preferably 0.7 mm or less, because further improved speed performance and rotation performance can be achieved. The height h of the protrusion is not limited thereto, but is preferably 0.45 mm or more.

[0061] The adjustment of the thickness T, the area percentage ar, and the height h of the protrusions in the rubber sheet 24 is not limited to a specific method, and those skilled in the art can appropriately set them, for example, through mold changes.

[0062] Therefore, according to the present embodiment, due to the configuration of the rubber sheet having a thickness T of 1.6 mm or less and an ar / h of 52 or more, the table tennis rubber 20 can exhibit improved speed performance and spin performance.

[0063] Therefore, a table tennis racket configured with the table tennis rubber 20 of the present embodiment allows the user to achieve increased ball hitting speed and to apply higher spin on the ball hitting, although the degree varies depending on the user.

[0064] Example

[0065] Hereinafter, the table tennis rubber of the present embodiment will be described in more detail by way of examples; however, the present invention is not limited to these examples in any way.

[0066] Rubber sheets having different thicknesses T, area percentages ar, and protrusion heights h were prepared by molding the materials of the formulations shown in Table 1 using an 8-inch mixing roll and a vulcanizer. The production method was as follows.

[0067] First, the metal mold was heated to 152° C., the material was placed in the metal mold and pressurized to 10 MPa. Subsequently, the pressure was applied for 471 seconds, and the resultant was taken out of the metal mold to obtain a rubber sheet.

[0068] [Table 1]

[0069] Polymers / Chemicals Rubber sheet formula 1 Rubber sheet formula 2 Natural rubber 100 Isoprene rubber 100 Calcium carbonate*1 15 15 Stearic acid 1 1 Zinc Oxide 5 5 Sulfur*2 2.5 2.5 Catalyst 1*3 0.4 0.4 Catalyst 2*4 0.4 0.4 total 124.3 124.3

[0070] (by quality)

[0071] *1 Calcium carbonate: NEOLIGHT SA300 manufactured by Takehara Chemical Industry Co., Ltd.

[0072] *2Sulfur: Precipitated sulfur "Golden Flower" produced by Tsurumi Chemical Co., Ltd.

[0073] *3 Catalyst 1: Nocceler DM-P manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0074] *4 Catalyst 2: ACCEL D manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0075] The obtained rubber sheets were each attached to a sponge-like sheet derived from a natural rubber having the hardness and density shown in Table 2; thereby, table tennis rubbers of Examples and Comparative Examples were prepared.

[0076] The speed performance and spin performance of the table tennis rubber were evaluated.

[0077] [Table 2]

[0078] hardness <![CDATA[Density [g / cm 3 > Sponge-like sheet 36 0.41

[0079] The hardness was measured using an automatic rubber hardness tester P1 manufactured by Kobunshi Keiki Co., Ltd. The measuring method was in accordance with JIS K 6253. The weight and volume were measured, and the density was calculated by "weight / volume".

[0080] Specifically, the evaluation was conducted according to the following procedure.

[0081] First, the rubber was adhered to a table tilted at 45 degrees with double-sided tape. Subsequently, a billiard ball (manufacturer: Butterfly, product name: Samsung Ball R40+) was hit onto the rubber using a billiard machine. At that time, the ball speed and ball rotation rate were set to 11.0 m / s and 150 rps, respectively. A camera (manufacturer: Nano Image Technology Co., Ltd., product name: MEMRECAM fx K4) was used to capture images from the moment immediately before the ball hit the rubber to the moment immediately after that (particularly 10 ms before and after the impact).

[0082] Based on the obtained images, the ball speed and ball spin rate were calculated using analysis software (manufacturer: NAC Image Technology Co., Ltd., software: LAA Measurement) immediately before and after hitting the rubber. In addition, for the table tennis rubbers of the examples and comparative examples, the "energy efficiency" of the hit was calculated based on the ball speed and ball spin rate determined before and after hitting the ball. The results are shown in Table 3. Note that each "energy efficiency" shown is calculated as the average of two shooting results.

[0083] Each energy efficiency determined is a value indicating the power of the shot, with a higher energy efficiency value indicating less energy lost from the ball after the shot.

[0084] If the energy loss is small, the translation energy and rotation energy of the ball before hitting the ball are effectively transferred, thereby achieving a higher hitting speed. This leads to easier hitting and smashing at high speeds, for example.

[0085] If the energy loss is small, the translation energy and rotation energy of the ball before hitting the ball are effectively transferred, so that the enhanced spin performance is also achieved. For example, this makes it easy to drive, slice and serve with spin.

[0086] The energy efficiency is calculated according to the following formula.

[0087] [Formula 1]

[0088]

[0089] m: mass of the ball (kg)

[0090] v 1 : Ball speed before impact (m / s)

[0091] v 2 : Ball speed after impact (m / s)

[0092] I: Moment of inertia of the ball (kg·m 2 )

[0093] ω 1 : Ball rotation before impact (rad)

[0094] ω 2: The rotation of the ball after impact (rad)

[0095] [Table 3]

[0096]

[0097]

[0098] As can be seen from Table 3, the table tennis rubbers of these examples all have a structure in which the thickness T is 1.6 mm or less and the ar / h is 52 or more, and exhibit higher speed performance and spin performance.

[0099] Reference numerals list

[0100] 10: racket board, 20: table tennis rubber, 22: sponge sheet, 24: rubber sheet, 26: protrusion, 100: table tennis racket

Claims

1. A billiard rubber, comprising: spongy sheets; and a rubber sheet laminated and adhered to the sponge-like sheet, the rubber sheet having a plurality of protrusions formed on a bonding surface of a main body of the rubber sheet with the sponge-like sheet, wherein the rubber sheet has a thickness of 1.6 mm or less in the stacking direction of the sponge-like sheets, and ar / h is 52 or more, wherein ar represents a value of an area percentage (%) of the protrusion relative to the bonding surface, and h represents a value of a height (mm) of the protrusion.

2. The table tennis rubber according to claim 1, wherein: ar / h is 55 or above.

3. The table tennis rubber according to claim 1, wherein: ar / h is above 60.

4. The table tennis rubber according to claim 1, wherein: The protrusion has a height of 0.7 mm or less.

5. The table tennis rubber according to claim 1, wherein: The rubber sheet has a thickness of 1.5 mm or less in the stacking direction of the sponge-like sheets.

6. A table tennis racket, wherein: The table tennis rubber according to any one of claims 1 to 5 is adhered to the body of the racket.

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