JP5609047B2 - Table tennis rubber and table tennis racket - Google Patents

Description

  The present invention relates to a table tennis rubber and a table tennis racket.

  A rubber for hitting the ball is affixed to the table tennis racket blade. As the rubber, for example, a rubber formed by superposing a rubber sheet formed of a highly repellent rubber material and a sponge sheet is used.

  In order to hit a sharp smash, the rubber sheet and the sponge sheet must have high repellent properties. In this case, a highly repellent rubber is used as the material of the rubber sheet. On the other hand, in order to give a rotational force to the ball and to control the direction in which the ball flies, it is better that the contact time between the ball and the rubber is longer. Therefore, the rubber sheet can be struck by attaching a sponge to the back of the rubber sheet, reducing the compression rigidity by increasing the thickness of the rubber sheet, or reducing the compression rigidity of the rubber by providing protrusions on the rubber sheet. The contact time between the ball and rubber is adjusted by softening the surface.

  An actual rubber is required to have both high repulsion on the ball and the application of rotational force to the ball and control of the control at the same time. However, if the plastic material is added to the rubber sheet to soften the material of the rubber sheet in order to lengthen the contact time between the ball and the rubber, the rebound resilience is lowered and the high-speed hitting ball cannot be hit. Further, even if a highly repellent rubber sheet is used, the sponge on which the rubber sheet is bonded generally has a low rebound, so that the resilience of the rubber as a whole is reduced, making it difficult to hit a high-speed ball. In addition, some table tennis rubbers consist of a single rubber sheet, but these rubbers are generally hard and the contact time between the rubber and the ball is shortened, giving a rotational force to the ball. Becomes difficult.

  The following Patent Documents 1 to 8 disclose various types of rubbers, but these rubbers cannot simultaneously achieve high rebound on the ball and imparting rotation to the ball and controlling the control.

For example, the rubber disclosed in Patent Documents 1 to 4 is a rubber having a rubber sheet obtained by adding a highly repellent polybutadiene rubber to a base rubber component. The rubber sheets in Patent Documents 1 to 4 are estimated to have a Young's modulus E ′ of about 3.5 MPa and a loss tangent tan δ of about 0.011. The rubber sheet having such a high Young's modulus is considered to exhibit extremely high repulsion. Therefore, the rubber made from the rubber sheet alone can return at a high speed, but the contact time between the rubber sheet and the ball is high. Is short, and sufficient rotational force cannot be applied to the ball.
In the rubber disclosed in Patent Documents 1 to 4, the Young's modulus of the rubber sheet may be lowered in order to increase the contact time between the rubber sheet and the ball. For example, means such as addition of plastic components such as oil and foaming of rubber can be considered. However, the addition of a plastic component and the foaming of rubber simultaneously increase the loss tangent tan δ. When the loss tangent tan δ increases, the resilience is greatly reduced.
Furthermore, the rubber sheet disclosed in Patent Documents 1 to 4 can be provided with a protrusion, and a rubber in which the protrusion of the rubber sheet is bitten into the sponge can be used. In such a rubber, it becomes possible to supplement the flexibility of the rubber sheet by the sponge, and it is possible to lengthen the contact time between the rubber sheet and the ball. However, since the sponge is less repulsive than the rubber sheet, energy is dissipated by the sponge at the time of hitting, and the speed of the ball is reduced.

  In addition, the materials introduced in these materials generally tend to change their physical properties due to temperature changes and changes over time, and as the temperature of the game hall rises, the Young's modulus decreases and the loss tangent tanδ increases. The repulsion and rotation of the player changes, the player feels a sense of hitting and control, and misplays tend to increase.

Patent Document 8 discloses a rubber having a rubber sheet having a loss tangent tan δ of 0.01 to 0.04 and a complex elastic modulus E ^{* of 1} to 4 MPa. Here, when the loss tangent tan δ is small, the real part of the complex elastic modulus E ^* approximates the Young's modulus. In Patent Document 8, since the loss tangent tan δ is sufficiently small, the complex elastic modulus E ^* is an approximate value of its real part. Therefore, the rubber sheet of Patent Document 8 is a rubber sheet having a loss tangent tan δ of 0.01 to 0.04 and a Young's modulus of approximately 1 to 4 MPa. A rubber sheet having a Young's modulus of 1 to 4 MPa exhibits a relatively low repulsion, but is still not sufficient in terms of imparting rotational force to the ball and controlling the ball.

  Further, Patent Document 5 or 9 discloses a rubber having a foamed rubber molded body or a rubber molded body containing bubbles. However, since a foamed rubber molded body or a rubber molded body containing bubbles cannot be obtained with a small loss tangent tan δ, only a rubber with low rebound can be obtained, making it difficult to return balls at high speed.

JP 2004-8714 A JP 2004-24662 A JP 2004-41370 A JP 2004-97556 A JP 2004-244505 A JP-A-2004-255070 JP 2004-305602 A Japanese Patent Laid-Open No. 2004-254808 JP 2004-89551 A

  The present invention has been made in view of the above circumstances, and is excellent in high repulsion for the ball, imparting rotational force to the ball and controlling the control, and further, the physical properties may change due to temperature change or aging. An object of the present invention is to provide a table tennis rubber and a table tennis racket which can obtain a stable hit feeling and controllability in any venue environment.

Rubber for table tennis invention, an elastic sheet made of silicone rubber having a siloxane bond, said elastic sheet is Ri foamed rubber sheet der that is foamed by hydrogen, the elastic body sheet, organo hydroxy siloxane is formed by curing by reacting a kind and organohydrogen siloxanes, bubble volume content of 30% or more and closed cell ratio and said foamed rubber sheet der Rukoto more than 60%.
In the table tennis rubber of the present invention, it is preferable that a silica filler is added to the elastic sheet.
Moreover, the table tennis racket of the present invention is characterized in that the rubber described in any of the above is provided.

Since the rubber of the present invention is provided with an elastic sheet made of silicone rubber having a siloxane bond, the resilience to the ball can be increased and the hitting speed can be increased. Further, by providing the elastic sheet, the contact time between the rubber and the ball at the time of hitting becomes longer, so that the ball can be easily rotated and the controllability of the hit ball can be improved. .
In addition, the use of silicone rubber makes it difficult for the physical properties to change due to temperature changes and changes over time, and even when the temperature of the game venue changes, players feel uncomfortable in terms of ball speed, rotation, direction, control or feel. There is no feeling, you can always play in the same condition, you can reduce the frequency of miss play.

FIG. 1 is a schematic cross-sectional view showing a first example of a table tennis rubber according to an embodiment of the present invention. FIG. 2 is a graph showing the relationship between the Young's modulus E ′ and the loss tangent tan δ of the rubber sheet constituting the table tennis rubber. FIG. 3 is a schematic diagram for explaining the effect when closed cells are provided in the rubber sheet. FIG. 4 is a schematic cross-sectional view showing a second example of the table tennis rubber according to the embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a third example of the table tennis rubber according to the embodiment of the present invention. FIG. 6 is a process diagram illustrating an example of a method for manufacturing the rubber shown in FIG. FIG. 7 is a process diagram illustrating another example of the rubber manufacturing method shown in FIG. FIG. 8 is a schematic cross-sectional view showing a fourth example of the table tennis rubber according to the embodiment of the present invention. FIG. 9 is a schematic cross-sectional view showing a fifth example of the table tennis rubber according to the embodiment of the present invention. FIG. 10 is a schematic cross-sectional view illustrating a sixth example of the table tennis rubber according to the embodiment of the present invention. FIG. 11 is a schematic cross-sectional view showing still another example of the table tennis rubber according to the embodiment of the present invention. FIG. 12 is an electron micrograph of the rubber sheet of Experimental Example 1. FIG. 13 is a graph showing the relationship between the ball contact time and Young's modulus in Experimental Examples 2 to 8. FIG. 14 is a graph showing the relationship between the elastic modulus and loss tangent of Experimental Example 1 and temperature. FIG. 15 is a graph showing the relationship between the rebound resilience coefficient and the closed cell ratio. FIG. 16 is a graph showing the relationship between rubber restitution coefficient and loss tangent. FIG. 17 is a graph showing the relationship between the elastic modulus and loss tangent of Experimental Example 9 and temperature. FIG. 18 is a graph showing the relationship between the elastic modulus and loss tangent of Experimental Example 10 and temperature.

(First example of rubber for table tennis)
A first example of a table tennis rubber according to an embodiment of the present invention will be described with reference to the drawings.
A table tennis rubber 1 shown in FIG. 1 is a back soft rubber, and is formed by laminating a sponge sheet 2 and a rubber sheet 3. The upper surface of the rubber sheet 3 is a ball striking surface 3a, and the lower surface of the sponge sheet 2 is an adhesive surface 2a bonded to a blade 4 of a table tennis racket. A plurality of protrusions 3 b are provided on the surface of the rubber sheet 3 on the sponge sheet 2 side, and the tops of the protrusions 3 b are joined to the sponge sheet 2.

  The rubber sheet 3 is composed of an elastic sheet made of silicone rubber having a siloxane bond (—O—Si—). This silicone rubber may be foamed. The thickness of the rubber sheet 3 excluding the protrusions 3b is preferably 0.02 to 2.0 mm. The height of the protrusion 3b is preferably 0.03 to 2.0 mm. The elastic sheet preferably has a Young's modulus E ′ of 0.01 MPa to 1 MPa and a loss tangent tan δ of 0.03 or less.

  In addition, the sponge sheet 2 is preferably made of one kind or a mixture of two or more kinds of silicone rubber, nitrile rubber, urethane rubber, butadiene rubber and natural rubber. The bubble volume content and the independent foaming rate of the sponge sheet 2 are preferably such that the bubble volume content is 30 to 80% and the independent foaming rate is 60 to 100%. The thickness of the sponge sheet 2 is preferably about 1.0 to 3.9 mm.

If the Young's modulus E ′ of the rubber sheet 3 is 0.01 MPa or more, the rubber sheet 3 becomes relatively hard, the contact time between the rubber sheet 3 and the ball at the time of hitting is shortened, and the direction of the hit ball is Less affected by rotation. Thereby, the controllability of the hit ball is improved. If the Young's modulus E ′ is 0.01 MPa or more, it is practical because the strength of the rubber sheet 3 does not decrease and the shape retainability increases. If the Young's modulus E ′ is 1 MPa or less, the rubber sheet 3 will not be too hard, and the contact time between the rubber sheet 3 and the ball at the time of impact will be relatively long, and a sufficient rotational force can be applied to the ball. A more preferable range of Young's modulus E ′ is a range of 0.02 MPa to 1 MPa.
It should be noted that the Young's modulus can be adjusted by, for example, filling the silicone rubber into the molding die at the time of manufacture as will be described later.

  Further, by setting the loss tangent tan δ to 0.03 or less, the energy loss when the ball collides with the rubber sheet 3 can be reduced, and there is no possibility of reducing the hitting ball speed. A more preferable range of the loss tangent tan δ is 0.02 or less. The lower limit of the loss tangent tan δ is preferably 0.003 or more, but may be smaller than this.

  FIG. 2 shows the relationship between the loss tangent tan δ and Young's modulus. Many conventional rubbers include a rubber sheet made of butadiene rubber. The loss tangent tan δ and Young's modulus of the rubber sheet made of butadiene rubber are distributed in the region C in FIG. Some butadiene rubbers have a small loss tangent tan δ, but the Young's modulus E ′ becomes high. On the other hand, when the butadiene rubber is softened by adding a plastic component or an oil and the Young's modulus E ′ is set to 1.0 or less, the loss tangent tan δ increases.

  Furthermore, when butadiene rubber is foamed, its loss tangent tan δ and Young's modulus are distributed in the region D in FIG. When the relationship between the loss tangent tan δ and the Young's modulus is in the region D, the Young's modulus E ′ decreases, but the loss tangent tan δ is large and the rebound of the ball decreases.

  Therefore, a rubber sheet made of butadiene rubber has a sponge sheet placed underneath it to reduce the overall compression rigidity and increase the contact time between the ball and the rubber, ensuring a high rotational force and hitting speed. . However, many sponge sheets have a small loss tangent tan δ and have a low coefficient of restitution, so that energy is lost in the sponge sheet and the rebound of the ball is reduced.

  On the other hand, the loss tangent tan δ and Young's modulus of the rubber sheet of the present embodiment are in the region A of FIG. 2 (region where the Young's modulus is 0.01 to 1.0 MPa and the loss tangent tan δ is 0.03 or less), preferably B (Region where Young's modulus is 0.02 to 1.0 MPa and loss tangent tan δ is 0.02 or less). As shown in FIG. 2, the rubber sheet 3 of this example has a longer contact time between the ball and the rubber sheet 3 at the time of hitting and can give a strong rotation to the ball, and at the same time has a repulsive property to the ball. The ball hitting speed can be increased.

  Examples of the material having a Young's modulus falling within the region B in FIG. 2 include silicone rubber having a siloxane bond as described above, and foamed silicone rubber is more preferable. In order to reduce the loss tangent tan δ to 0.03 or less while maintaining the Young's modulus at 0.01 to 1.0 MPa, the bubble volume content of the foamed silicone rubber is 30% or more and the independent foaming ratio is 60. % Or more.

  FIG. 3 shows a state in which the ball collides with the foamed rubber sheet 3. FIG. 3A shows a case where all the bubbles in the rubber sheet 3 are independent bubbles, and FIG. 3B shows a case where all the bubbles in the rubber sheet 3 are continuous bubbles. As shown in FIG. 3A, if all the bubbles are independent bubbles, the striking surface 3a is deformed by the pressure of the ball 5 and the air inside the independent bubbles is compressed. By the compression of air, the kinetic energy of the ball 5 at the time of hitting is accumulated as the elastic energy of the rubber sheet 3 and the compression energy of the air in the independent foam. Thereafter, the accumulated energy is released and a repulsive force is applied to the ball 5. Although the loss tangent of air in the independent foam is originally small, the energy dissipated as heat in the rubber sheet 3 is also small when the loss tangent of the rubber sheet 3 is small. For this reason, since the elastic energy of the stored rubber sheet 3 and the elastic energy of air become repulsive energy, the ball 5 rebounds greatly.

  On the other hand, as shown in FIG. 3B, when the bubbles are continuous bubbles, the rubber sheet 3 is deformed by the impact pressure of the ball 5 and the air inside the bubbles is compressed. In addition, the air leaks outside through the adjacent bubbles, and the elastic energy to be stored in the bubbles is immediately lost. For this reason, the repulsive energy which should be usable becomes small, and the ball 5 does not bounce.

By setting the bubble volume content of the rubber sheet 3 to 30% or more and the independent foaming ratio to 60% or more, the loss tangent tan δ can be lowered without increasing the Young's modulus, and the rebound resilience coefficient is Since it becomes high, it is possible to improve all of the resilience to the ball, the imparting of rotation and the controllability of the hit ball.
In addition, the use of the repulsion due to air is less likely to cause inconvenience that the repulsion rate changes depending on the temperature.

The rubber sheet 3 can be produced by reacting and curing an organohydroxysiloxane and an organohydrogensiloxane in the presence of a catalyst and simultaneously foaming. When the organohydroxysiloxanes and the organohydrogensiloxanes undergo a curing reaction, hydrogen is generated, and the rubber sheet 3 is foamed by the hydrogen. The bubble volume content can be controlled by the mixing ratio of the organohydroxysiloxanes and the organohydrogensiloxanes. The firing rate can also be adjusted by the amount of silicone rubber filled in the mold.
A platinum compound etc. can be used as a catalyst. By performing the curing reaction in the mold, the rubber sheet 3 having a plurality of protrusions 3b on the surface opposite to the striking surface can be manufactured.

As the organohydroxysiloxanes, those in which a part of methyl groups in the linear organopolysiloxane are substituted with hydroxyl groups as shown in the following formula (1), and those with n = about 3 to 100 are preferable. .
Moreover, as organohydrogensiloxanes, as shown in the following formula (2) or (3), a part of methyl groups in a linear organopolysiloxane is substituted with hydrogen, and n = 3 to 3 A thing of about 100 is good.
Further, in addition to these siloxanes, as a base resin, a linear n-substituted dimethyl group having both ends of about 50, which is a straight chain in which both ends of a molecular chain are blocked with vinyl groups, as shown in the following formula (4): Polysiloxane may be added.

In addition to these siloxanes, as an additional component, a complex of fine platinum supported on alumina or the like, secondary platinum chloride, chloroplatinic acid, chloroplatinic acid hexahydrate, and olefin or divinyldimethylpolysiloxane Are used as a catalyst for the reaction in an amount of about 1 to 500 ppm.
The hydrogen group equivalent of the organohydrogensiloxane (B) is equal to the total value of the hydroxyl group equivalent of the organohydroxypolysiloxane (A) and the vinyl group equivalent of the vinyl terminal-substituted dimethylpolysiloxane (C). If they are blended in such a ratio, the dehydrogenative condensation reaction of (A) and (B) and the addition reaction of (A) and (C) proceed without excess or deficiency. You may mix (A) somewhat.

The Young's modulus of the rubber sheet 3 can be adjusted by the amount of silicone rubber filled in the mold. For example, if the filling amount of the silicone rubber is 90% with respect to the inner volume of the mold and the foaming ratio is 1.1 times, the hardness of the silicone rubber becomes relatively hard and the elastic modulus becomes about 1.2 MPa. . When silica filler is further added, the hardness of the silicone rubber is further increased and a Young's modulus of about 2.1 MPa is obtained.
On the other hand, when the filling amount of the silicone rubber is 33% with respect to the mold and the expansion ratio is 3 times, the silicone rubber becomes relatively soft and the elastic modulus becomes about 0.15 MPa. When a foaming agent is further added and additional foaming is performed at the time of curing, the foaming ratio is further increased and a Young's modulus of about 0.034 MPa is obtained.

Moreover, the Young's modulus of the rubber sheet 3 can also be reduced by adding an additive such as isocyanate ethoxysilane to lower the crosslink density and soften it.
Furthermore, the Young's modulus of the rubber sheet 3 can be lowered by reducing the organohydrogenpolysiloxane to lower the crosslinking density. As described above, the Young's modulus can be adjusted.

  And the rubber 1 of this example can be manufactured by bonding the manufactured rubber sheet 3 to the sponge sheet 2.

(Second example of rubber for table tennis)
FIG. 4 shows a second example of rubber for table tennis. The rubber 11 in this example is composed only of a flat rubber sheet 13. The upper surface of the rubber sheet 13 is a striking surface 13a for the ball, and the surface opposite to the striking surface 13a is an adhesive surface 13d bonded to the blade 4 of the table tennis racket. The striking surface 13a of the rubber sheet 13 is a flat surface.

  As in the first example, the rubber sheet 13 is made of an elastic sheet made of silicone rubber having a siloxane bond, and more preferably foamed silicone rubber. The foamed silicone rubber preferably has a cell volume content of 30% or more and an independent foaming rate of 60% or more. The thickness of the rubber sheet 13 is preferably 1.0 to 3.9 mm.

  The rubber 11 of this example is one in which the sponge sheet is omitted as compared with the first example, but the rubber sheet 13 itself is soft. Sufficient contact time with the ball can be obtained at the time of hitting. Since the contact time is long, it is possible to give a sufficient time to give rotation acceleration and to give a strong rotation to the ball. At the same time, since the rubber sheet 13 has high rebound resilience, a high-speed hit ball can be hit.

  The rubber sheet 13 of this example can be manufactured in the same manner as in the first example.

(Third example of rubber for table tennis)
Next, FIG. 5 shows a third example of a table tennis rubber. The rubber 21 in this example is configured by laminating a rubber sheet 26 on a sponge sheet 23. The upper surface of the rubber sheet 26 is a striking surface 26a for the ball, and the surface opposite to the striking surface 26a side of the sponge sheet 23 is an adhesive surface 26d bonded to the blade 4 of the table tennis racket. The striking surface 26a of the rubber sheet 26 is a flat surface.

  The sponge sheet 23 is composed of an elastic sheet made of silicone rubber having a siloxane bond, and more preferably foamed silicone rubber. The thickness of the sponge sheet 23 is preferably 1.0 to 3.9 mm. In the case of foamed silicone rubber, it is preferable that the bubble volume content is 30% or more and the independent foaming rate is 60% or more.

Examples of the rubber sheet 26 include rubber sheets such as natural rubber, butyl rubber, or nitrile rubber having a large friction coefficient, high-strength natural rubber, butadiene rubber, or urethane rubber. In order to make use of the characteristics of the sponge sheet 23, it is desirable that the rubber sheet 26 be as thin as possible, for example, about 0.3 mm.
According to the rubber 21 of this example, by laminating the rubber sheet 26 on the sponge sheet 23, a stronger rotational force can be applied to the ball, and at the same time, the durability of the rubber 21 can be enhanced.

  As an example of the manufacturing method of the rubber 21 of this example, as shown in FIG. 6A, a rubber sheet 26 is arranged in advance on the lower mold 27 of the mold. At this time, in order to prevent the silicone rubber from being inhibited from curing, it is preferable to apply a curing inhibitor to the rubber sheet 26. Next, as shown in FIG. 6B, after the resin 23e before curing is injected, the upper die 28 is fitted into the lower die 27 to form a molding die. Next, as shown in FIG. 6C, the sponge sheet 23 is formed on the rubber sheet 26 by curing and foaming the resin 23e before being cured. Thereafter, the rubber 21 of this example can be manufactured by removing the mold as shown in FIG. As resin 23e before hardening, what was illustrated as a raw material of the rubber sheet of the 1st example can be used.

  Further, as another example of the method for manufacturing the rubber 21 of this example, as shown in FIG. 7A, a sponge sheet 23 is formed, and a silicone adhesive 29 is applied on the sponge sheet 23, The rubber sheets 26 are overlapped. Next, as shown in FIG. 7B, the rubber 21 of this example can be manufactured by bonding the sponge sheet 23 and the rubber sheet 26. The raw material of the sponge sheet 23 can be the same as the raw material of the rubber sheet of the first example.

(Fourth example of rubber for table tennis)
FIG. 8 shows a fourth example of a table tennis rubber. The rubber 31 in this example is a front soft rubber, and is configured by laminating a sponge sheet 32 and a rubber sheet 33. The upper surface of the rubber sheet 33 is a ball striking surface 33a, and the lower surface of the sponge sheet 32 is an adhesive surface 32a bonded to the blade 4 of the table tennis racket. A plurality of protrusions 33 b are provided on the striking surface 33 a of the rubber sheet 33. The sponge sheet 32 may be the same as that in the first example.

  As in the first example, the rubber sheet 33 is formed of an elastic sheet made of silicone rubber having a siloxane bond, and more preferably foamed silicone rubber. The foamed silicone rubber preferably has a cell volume content of 30% or more and an independent foaming rate of 60% or more. The thickness excluding the protrusion 33b of the rubber sheet 33 is preferably 0.02 to 2.0 mm. The height of the protrusion 33b is preferably 0.03 to 2.0 mm.

In this example, by providing the protrusion 33b on the impact surface 33a side of the rubber sheet 33, the compression rigidity of the rubber sheet 33 is reduced as compared with the case of the third example, whereby the ball and the rubber sheet 33 at the time of impact are reduced. The contact time with the ball becomes longer, and it becomes easier to apply a rotational force to the ball. Originally, the front soft rubber has a high hitting speed, so that it can hit a hitting ball with high speed and sufficient rotation.
Further, by providing the sponge sheet 32, the compression rigidity of the entire rubber 31 can be reduced, and it becomes easier to apply a rotational force to the ball.

(Fifth example of rubber for table tennis)
The rubber 41 of this example shown in FIG. 9 is a back soft rubber, and is configured by laminating a sponge sheet 42 and a rubber sheet 43. The upper surface of the rubber sheet 43 is a striking surface 43a, and the lower surface of the sponge sheet 42 is bonded. It is set as the surface 42a. A plurality of protrusions 43 b are provided on the surface of the rubber sheet 43 on the sponge sheet side, and the tops of the protrusions 43 b are joined to the sponge sheet 42.

The sponge sheet 42 of the rubber 41 in this example is made of an elastic sheet made of silicone rubber having a siloxane bond, and more preferably foamed silicone rubber. The thickness of the sponge sheet 42 is preferably about 1.0 to 3.9 mm. In the case of foamed silicone rubber, the cell volume content is preferably 30 to 80%, and the independent foaming rate is preferably 60 to 100%.
The rubber sheet 43 of the rubber 41 of this example is made of a material such as natural rubber, butadiene rubber, nitrile rubber, urethane rubber, or silicone rubber. The thickness of the rubber sheet 43 excluding the protrusions 43b is preferably 0.02 to 2.0 mm. The height of the protrusion 43b is preferably 0.03 to 2.0 mm.

  In the rubber 41 of this example, a sponge sheet 42 is provided below the rubber sheet 43, and the compression rigidity of the rubber 41 as a whole can be reduced by deforming the sponge sheet 42 when hit. Thereby, the contact time between the ball and the rubber 41 at the time of hitting is prolonged, and a large rotational force can be applied to the ball. Further, since the sponge sheet 42 is composed of the sheet according to the present invention, the repulsive force of the entire rubber 41 can be increased, and the hitting speed can be increased.

(Sixth example of table tennis rubber)
The rubber 51 of this example shown in FIG. 10 is a back soft rubber, and is configured by laminating a sponge sheet 52 and a rubber sheet 53, the upper surface of the rubber sheet 53 is a striking surface 53a, and the lower surface of the sponge sheet 52 is bonded. It is set as the surface 52a. A plurality of projections 53 b are provided on the surface of the rubber sheet 53 on the sponge sheet side, and the tops of the projections 53 b are joined to the sponge sheet 52.

  The rubber sheet 53 and the sponge sheet 52 of the rubber 51 of this example are both made of an elastic sheet made of silicone rubber having a siloxane bond. The rubber sheet 53 and the sponge sheet 52 are preferably made of foamed silicone rubber. The foamed silicone rubber preferably has a bubble volume content of 30% or more and an independent foaming ratio of 60% or more. Moreover, it is preferable that the bubble volume content of the rubber sheet 53 is lower than the bubble volume content of the sponge sheet 52. The thickness of the rubber sheet 53 excluding the protrusions and the height of the protrusions may be the same as in the first example. The sponge sheet 52 may be the same as the sponge sheet of the fifth example except that the bubble volume content is higher than that of the rubber sheet 53.

  According to this example, since both the rubber sheet 53 and the sponge sheet 52 are composed of the elastic sheet according to the present invention, it is possible to improve all of the repulsion of the ball, the application of rotational force, and the controllability at the time of hitting. .

The table tennis rubber of the present invention is not limited to the above embodiment, and may be described below.
The table tennis rubber 61 shown in FIG. 11A is a front soft rubber, and is configured by laminating a sponge sheet 62 and a rubber sheet 63. In this example, the rubber sheet 63 is composed of a rubber sheet such as natural rubber, butyl rubber, nitrile rubber, butadiene rubber, or urethane rubber. On the other hand, the sponge sheet 62 is composed of an elastic sheet according to the present invention.
The table tennis rubber 71 shown in FIG. 11B is composed of only a rubber sheet 73. In this example, the upper surface of the rubber sheet 73 is a striking surface 73 a, a plurality of protrusions 73 b are provided on the rubber sheet 73 on the racket blade 4 side, and the top of the protrusion 73 b is joined to the racket blade 4. The rubber sheet 73 is composed of an elastic sheet according to the present invention.

The table tennis rubber 81 shown in FIG. 11C is composed of only a rubber sheet 83. In this example, the upper surface of the rubber sheet 83 is a striking surface 83a, and a plurality of protrusions 83b are provided on the striking surface 83a. The rubber sheet 83 has a flat surface on the racket blade 4 side, and the flat surface is joined to the racket blade 4. The rubber sheet 83 is composed of an elastic sheet according to the present invention.
A table tennis rubber 91 shown in FIG. 11 (d) is composed of only a sponge sheet 92. The sponge sheet 92 is composed of an elastic sheet according to the present invention. Since the rubber 91 in this example is soft, a sufficient contact time is obtained with respect to the ball at the time of hitting and a strong rotational force can be applied to the ball. At the same time, since the sponge sheet 92 has high rebound resilience, it is possible to hit a ball with speed.

  A table tennis rubber 101 shown in FIG. 11E is configured by laminating a rubber sheet 103 and a sponge sheet 102. The rubber sheet 103 is composed of an elastic sheet according to the present invention. The sponge sheet 102 is made of natural rubber, butyl rubber, nitrile rubber, butadiene rubber, urethane rubber, or the like, and more preferably foamed rubber.

As described above, according to the table tennis rubber of this embodiment, the resilience to the ball can be increased and the hitting speed can be increased. In addition, by providing the elastic sheet as a rubber sheet or sponge sheet, the contact time between the rubber and the ball at the time of hitting is increased, and the ball can be easily rotated, and the controllability of the hit ball Can be increased.
Further, by using silicone rubber, the physical properties do not change due to temperature changes. Thereby, even if there is a change in the temperature of the game hall, the speed, rotation, direction, control or feel of the ball does not change, and the deterioration of physical properties with time is also reduced.

(Experimental example 1)
As the two-component liquid rubber, Tosfoam 300 (trade name) manufactured by Momentive Performance Materials Japan was used, and 83.5 ml each of the main agent (A agent) and the curing agent (B agent) were weighed and mixed well. Next, the mixture was filled in a mold having an internal volume of 500 ml. The filling amount of silicone rubber in the mold was set to 33%, and the foaming ratio was set to 3 times. Thereafter, curing and foaming were started after 10 minutes at room temperature, and curing and foaming were terminated after 20 minutes. Then, the sponge sheet | seat of Experimental example 1 was manufactured by heat-processing on the conditions for 1 hour at 70 degreeC.

An electron micrograph of the obtained sponge sheet is shown in FIG. As shown in FIG. 12, a large number of bubbles were formed in the sponge sheet. Moreover, when Young's modulus was measured, it was 0.16 MPa. Further, the loss tangent tan δ was 0.012 at 20 ° C. The density was 0.33 g / cm ³ .

(Experimental Examples 2-8)
Prepare agent A and agent B with 25% silica filler added by mass ratio, charge agent A (250 ml) and agent B (250 ml) in a 500 ml mold, and leave no voids in the mold to leave room for foaming. The sponge sheet of Experimental Example 2 was manufactured in the same manner as described above except that the mold was closed and cured in a state where foaming was not possible to obtain a substantially non-foamed cured product having a density of approximately 1.1 g / cm ³ . This sponge sheet had a Young's modulus of 2.9 MPa.

Also, A agent 208 ml, was charged with B agent 208 ml in a mold of 500 ml, the foaming ratio of 1.2 times, except that the density is substantially cured product of 0.83 g / cm ³ in the same manner as above, Experiment 3 A sponge sheet was manufactured. This sponge sheet had a Young's modulus of 0.95 MPa.

Further, Experimental Example 4 was carried out in the same manner as above except that 125 ml of Agent A and 125 ml of Agent B were charged into a 500 ml mold to obtain a cured product having an expansion ratio of 2.0 times and a density of approximately 0.5 g / cm ^3. A sponge sheet was manufactured. This sponge sheet had a Young's modulus of 0.32 MPa.

Further, Experimental Example 5 was carried out in the same manner as above except that 75 ml of Agent A and 75 ml of Agent B were charged into a 500 ml mold to obtain a cured product having an expansion ratio of 3.3 times and a density of approximately 0.3 g / cm ^3. A sponge sheet was manufactured. This sponge sheet had a Young's modulus of 0.11 MPa.

Also, 95 ml of agent A and 55 ml of agent B are charged into a 500 ml mold, softened by reducing the agent B and reducing the crosslinking density, and the foaming ratio is 3.3 times and the density is approximately 0.3 g / cm ³ . A sponge sheet of Experimental Example 6 was produced in the same manner as described above except that the cured product was used. This sponge sheet had a Young's modulus of 0.019 MPa.

Furthermore, 110 ml of A agent and 40 ml of B agent are charged into a 500 ml mold, and isocyanate ethoxylane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE9007) that reduces the crosslinking density by reducing the crosslinking agent B agent and further promotes softening is 0. The sponge sheet of Experimental Example 7 was manufactured in the same manner as described above except that 0.1 g was added to obtain a cured product having an expansion ratio of 3.3 times and a density of approximately 0.3 g / cm ³ . This sponge sheet had a Young's modulus of 0.01 Pa.

Furthermore, 1 ml of isocyanate ethoxylane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE9007) that charges 115 ml of agent A and 35 ml of agent B in a 500 ml mold, reduces the crosslinking agent B agent, lowers the crosslinking density, and further promotes softening. A sponge sheet of Experimental Example 8 was produced in the same manner as described above except that a cured product having a foaming ratio of 3.3 times and a density of approximately 0.3 g / cm ³ was added. This sponge sheet had a Young's modulus of 0.005 MPa.

  The sponge sheets of Experimental Examples 2 to 8 were attached to a racket blade as table tennis rubber to produce a table tennis racket. About the obtained racket, the contact time with a ball | bowl was measured. FIG. 13 shows the relationship between the contact time and the rubber Young's modulus.

As shown in FIG. 13, the contact time between the sponge sheet and the ball becomes longer as the Young's modulus decreases. When the Young's modulus exceeds 1.0 MPa, the contact time with the ball is significantly reduced, and there is a possibility that the ball cannot be sufficiently rotated. On the other hand, when the Young's modulus of the sponge sheet is less than 0.01 MPa, the contact time exceeds 4 ms, so that the hitting speed is lowered and the strength of the sponge sheet is extremely lowered, and the durability is lost.
From this, it is understood that a sponge sheet having an elastic modulus of at least 0.01 MPa to 1 MPa, ideally 0.02 MPa to 1 MPa is desirable.

14 shows the temperature dependence of the dynamic storage elastic modulus E ′ (Young's modulus), dynamic loss elastic modulus E ″, and loss tangent tan δ for the rubber sheet of Experimental Example 1. As shown in FIG. In addition, in the range of −20 ° C. to 80 ° C., the values of E ′, E ″ and tan δ are almost constant, and it can be seen that the performance does not fluctuate due to temperature changes.
As a result, even if the temperature of the game venue changes or the temperature of the racket surface rises due to light lighting, the rebound, rotation, or hit feeling of the ball will not change, and the player will not feel uncomfortable , The frequency of miss play is also reduced.

  FIG. 15 shows the relationship between the closed cell ratio and the rebound resilience coefficient for the rubber sheets of Experimental Examples 1 to 8. It can be seen that when the closed cell ratio is 60% or more, the rebound resilience coefficient exceeds 0.6, indicating excellent rebound.

  Further, FIG. 16 shows the relationship between the loss tangent tan δ and the repulsion coefficient for various rubber sheet materials. The coefficient of repulsion was determined by the method of measuring the coefficient of repulsion by the steel ball dropping method of JIS K 6400-3. The prepared rubber sheets are the rubber sheet of Experimental Example 1, the rubber sheet made of butyl rubber (loss tangent tan δ = 0.61), the rubber sheet made of kuruprene rubber (loss tangent tan δ = 0.19), butadiene rubber and natural rubber. (A loss tangent tan δ = 0.07). As shown in FIG. 16, when the loss tangent tan δ exceeds 0.03, it can be seen that the rebound resilience coefficient is significantly reduced, and the hitting speed may be reduced.

(Experimental example 9)
Using Tosfoam 300 (trade name) manufactured by Momentive Performance Materials Japan, 200 ml each of the main agent (agent A) and the curing agent (agent B) were weighed and mixed well. Next, the mixture was filled in a mold having an internal volume of 500 ml. The filling amount of silicone rubber into the mold was set so that the expansion ratio was 1.25 times. Thereafter, curing and foaming started after 10 minutes at room temperature, and curing and foaming were completed after 20 minutes. Thereafter, the sponge sheet of Experimental Example 9 having a thickness of 4 mm was manufactured by heat treatment at 70 ° C. for 1 hour.

When the Young's modulus of the sponge sheet of Experimental Example 9 was measured, it was 0.91 MPa. Further, the loss tangent tan δ was 0.004 at 20 ° C. The density was 0.81 g / cm ³ .

The sponge sheet of Experimental Example 9 was attached to a racket blade as a table tennis rubber to produce a table tennis racket. About the obtained table tennis racket, the relationship between the elastic modulus and loss tangent and temperature was measured. The results are shown in FIG. When I tried this racket, I was able to hit a smash with a very fast ball speed. Although there is a slightly hard feel, there is a feeling that the contact time is slightly short, but a feeling that can impart sufficient rotational force to the ball was obtained. In other words, it became an aggressive racket with excellent speed and rotation.
As shown in FIG. 18, E ′, E ″ and tan δ are almost constant values at −20 ° C. to 80 ° C., and even if the temperature of the venue changes, the rebound, rotation and hit feeling of the ball do not change. The player does not feel uncomfortable and the frequency of miss play is reduced.

(Experimental example 10)
Using Tosfoam 300 (trade name) manufactured by Momentive Performance Materials Japan, 100 ml of the main agent (agent A) and 50 ml of the curing agent (agent B) were weighed and mixed well. Next, the mixture was filled in a mold having an internal volume of 500 ml. The filling amount of silicone rubber into the mold was set so that the expansion ratio was 3.3 times. Thereafter, curing and foaming started after 10 minutes at room temperature, and curing and foaming were completed after 20 minutes. Then, the sponge sheet | seat of Experimental example 10 of thickness 4mm was manufactured by heat-processing on conditions for 1 hour at 70 degreeC.

When the Young's modulus of the sponge sheet of Experimental Example 10 was measured, it was 0.025 MPa. Further, the loss tangent tan δ was 0.019 at 20 ° C. The density was 0.3 g / cm ³ .

The sponge sheet of Experimental Example 10 was attached to a racket blade as a table tennis rubber to produce a table tennis racket. About the obtained table tennis racket, the relationship between the elastic modulus and loss tangent and temperature was measured. The results are shown in FIG. When I tried this racket, it was very good in ball holding, was able to hit a ball with a fast ball speed and a sharp rotation. Since it has a soft feel, it has a slightly longer contact time, but it has a sufficient repulsive force. In other words, it became an aggressive racket with excellent speed and rotation.
As shown in FIG. 17, E ′, E ″, and tan δ are almost constant at −20 ° C. to 80 ° C., and even if the temperature of the venue changes, the rebound, rotation, and hit feeling of the ball do not change. The player does not feel uncomfortable and the frequency of miss play is reduced.

1, 2, 31, 41, 51... Rubber for table tennis, 42, 52... Sponge sheet (elastic body sheet), 3, 13, 23, 33, 54... Rubber sheet (elastic body sheet).

Claims (3)

An elastic sheet made of silicone rubber having a siloxane bond, said elastic sheet is Ri foamed rubber sheet der that is foamed by hydrogen,
The elastic sheet is a foamed rubber sheet formed by reacting and curing an organohydroxysiloxane and an organohydrogensiloxane, and has a bubble volume content of 30% or more and an independent foaming ratio of 60% or more. This is a table tennis rubber. 2. The table tennis rubber according to claim 1, wherein a silica filler is added to the elastic sheet. A table tennis racket comprising the rubber according to any one of claims 1 to 2 .

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