JP5028539B1 - MANUFACTURING METHOD FOR MULTI-LAYER RUBBERS FOR PING-POOL, MULTI-LAYER RUBBERS FOR PING-PIN RACES AND ADHESIVE FOR PEN-TEN - Google Patents

Abstract

[PROBLEMS] To provide an adhesive for a racket rubber and a method for producing a rubber / sponge laminate in a table tennis racket that can be applied to the bonding of various types of rubber sheets and sponge sheets by many manufacturers and has an excellent feel at impact. I will provide a.
An adhesive 16 for bonding a rubber sheet 12 and a sponge sheet 14 of a table tennis racket is an adhesive 16 having an isocyanate group obtained by reacting a hydrocarbon polyol compound and an aromatic polyisocyanate compound. . The adhesive 16 is used in the manufacturing method of the multilayer rubber. In the multi-layer rubber, a rubber sheet 12 and a sponge sheet 14 are laminated with an adhesive 16.
[Selection] Figure 1

Description

  The present invention relates to an adhesive for multilayer rubber used as a racket by adhering to a blade, which is a wooden base material for table tennis, and a method for producing a multilayer rubber.

  A table tennis racket is obtained by laminating a member called a rubber (multi-layer rubber as referred to in the present invention) on a surface of a basic member called a blade mainly made of wood. The multi-layer rubber has a structure in which a rubber sheet having a base material made of natural rubber having a large number of cylindrical protrusions having a diameter of about 1 mm on one side and a sponge sheet having a base material made of natural rubber are bonded and laminated. Adhesives for the production of multi-layer rubber in table tennis rackets are required to form a strong adhesive force that prevents the rubber sheet from peeling off from the sponge sheet and a feeling of hitting that the player is satisfied with. It has been known that the adhesive has a great influence on the shot feeling. Conventionally, an organic solvent rubber adhesive in which natural rubber is dissolved in an organic solvent, particularly toluene, has been used to obtain such adhesive strength and feel at impact.

  Since such a rubber-based adhesive contains an organic solvent such as toluene, when applied to a rubber sheet, the solvent penetrates the rubber sheet and swells it, so that the rubber sheet immediately after application is greatly curled. . Therefore, in order to produce a multilayer rubber, it is necessary to leave it for several weeks until the curl is settled, and the production efficiency of the multilayer rubber is extremely poor. Furthermore, while the organic solvent is volatile, it has the property of being absorbed by the laminated multi-layer rubber and remaining and gradually released over a long period after production. Since volatile organic solvents (VOC) are harmful to the human body, the International Table Tennis Federation (ITTF) prohibits the use of adhesives containing volatile organic solvents and regulates the amount of gas components (outgas) generated from the racket. ing.

  A technique using a water-based adhesive as an adhesive for producing a multilayer rubber that avoids such VOC regulations is known (Patent Document 1). The adhesive for producing a multilayer rubber disclosed in Patent Document 1 is an aqueous dispersion of a polyurethane resin, and preferably contains an SBR latex.

JP 2011-5111 A

  However, the water-based adhesive as disclosed in Patent Document 1 is one in which an adhesive is applied at the time of adhesion and dried, and then adhered by adhering the adhesive surface. Since the latex is easily deformed by shearing when pasted together with insufficient moisture and a lot of moisture remaining, the rubber sheet and the sponge sheet are displaced with a small force, and Since neither the rubber sheet nor the sponge sheet has moisture permeability, there is a problem that it takes a long time to obtain a predetermined adhesive force by drying especially when the flat surface of the rubber sheet is bonded to the sponge sheet. . In Patent Document 1, a vacuum dryer is used in order to perform drying quickly. However, since such a vacuum dryer requires pressure resistance, a large amount of capital investment is required to change the manufacturing method of the multi-layer rubber. And

Furthermore, while the water-based adhesive disclosed in Patent Document 1 uses polyester polyol or polyether polyol, there are many varieties of rubber sheets and sponge sheets to be bonded, which are manufactured by many manufacturers. In the case of none, it is not necessarily applicable to the bonding of all kinds of materials, and there is a problem that the adhesive force may not be sufficient.

In view of the problems of the above-mentioned known technology, the present invention is capable of bonding many types of rubber sheets and sponge sheets by many manufacturers without primer treatment, and is excellent in feel at impact. It is an object of the present invention to provide an adhesive for multilayer rubber, a method for producing a multilayer rubber (rubber / sponge laminate), and a multilayer rubber that can form a multilayer rubber.

The adhesive for bonding the rubber sheet and the sponge sheet of the table tennis racket of the present invention is an isocyanate group-containing prepolymer obtained by reacting a polyol compound containing 50% by weight or more of a hydrocarbon polyol compound with an aromatic polyisocyanate compound. polymer only contains, and having an isocyanate group.

  According to the adhesive having such a configuration, since the polyol component has high affinity to the rubber sheet and the sponge sheet and does not have the hydrophilic component, many kinds of rubber sheets and sponge sheets by many manufacturers are primed. It is possible to produce a multi-layer rubber that can form a table tennis racket that can be adhered without using a rugged ball and has an excellent feel at impact.

Another aspect of the present invention is a method for producing a multilayer rubber, that is, a multilayer rubber (rubber sheet / sponge sheet laminate) in which a rubber sheet of a table tennis racket and a sponge sheet are laminated,
An adhesive application step of applying an adhesive to at least an adhesive surface of the rubber sheet and the sponge sheet, an adhesive step of adhesively laminating the rubber sheet and the sponge sheet applied with the adhesive, and a multilayer rubber by curing the adhesive A curing step to
The adhesive viewed contains an isocyanate group-containing prepolymer obtained by reacting a polyol compound and an aromatic polyisocyanate compound containing a hydrocarbon-based polyol compound than 50 wt%, table tennis rackets double layer rubber having an isocyanate group It is an adhesive.

  According to the manufacturing method of such a configuration, since the polyol component which is a constituent component of the adhesive has a high affinity for the rubber sheet and the sponge sheet and does not have a hydrophilic component, many types of rubber sheets by many manufacturers are used. And a sponge sheet can be bonded to each other without a primer treatment, and a multi-layer rubber constituting a table tennis racket having an excellent feel at impact can be manufactured. Further, according to the production method of the present invention, a vacuum dryer is unnecessary, and a large capital investment is not required when changing the production method.

Another aspect of the present invention is a multilayer rubber bonded to a blade to form a table tennis racket, wherein a rubber sheet and a sponge sheet contain a polyol compound containing 50% by weight or more of a hydrocarbon-based polyol compound, an aromatic polyisocyanate compound, and seen containing an isocyanate group-containing prepolymer obtained by reacting, characterized in that the adhesive to cure the adhesive having an isocyanate group.

  In the multi-layer rubber having the above configuration, since the polyol component constituting the adhesive has high affinity to the rubber sheet and sponge sheet and does not have a hydrophilic component, many types of rubber sheets and sponge sheets by many manufacturers are used. Can be created according to the player's preference, and a table tennis racket with an excellent feel at impact can be constructed.

  The adhesive for bonding the rubber sheet and the sponge sheet of the table tennis racket of the present invention has an isocyanate group obtained by reacting a polyol compound containing 50% by weight or more of a hydrocarbon-based polyol compound with an aromatic polyisocyanate compound. The main component is a compound, so-called isocyanate group-terminated prepolymer. Examples of the hydrocarbon-based polyol compound include polybutadiene polyol, hydrogenated polybutadiene polyol, polyisoprene polyol and the like, and these can be used alone or in combination of two or more. These hydrocarbon polyol compounds have a functional group number, that is, an average number of hydroxyl groups per molecule of 2 to 4, and a molecular weight of 500 to 4000. The ratio of the hydrocarbon-based polyol compound in the polyol compound is more preferably 60% by weight or more.

The isocyanate group-terminated prepolymer contains 50% by weight or more of a hydrocarbon-based polyol compound, and is obtained by reacting a polyol compound containing another polyol compound with an aromatic polyisocyanate compound in excess of an isocyanate group as necessary. The NCO / OH equivalent ratio in the reaction is 2 or more, preferably 2.5 or more. The isocyanate group-terminated prepolymer may contain an unreacted isocyanate compound. The NCO / OH equivalent ratio is preferably 10 or less, and more preferably 8 or less. The content of the isocyanate group-terminated prepolymer in the adhesive is 60% by weight or more, and preferably 70% by weight or more, excluding the resin to be added.

  As the polyol compound that can be used in combination with the hydrocarbon-based polyol compound in the adhesive mainly composed of the prepolymer of the present invention, a polyol compound known in the technical field of polyurethane can be used. Of these, the use of polyether polyols such as polytetramethylene glycol (PTMG) and polypropylene glycol (PPG) is preferred because of their good compatibility with hydrocarbon polyol compounds.

  Examples of the aromatic polyisocyanate compound that is an adhesive component of the present invention include toluene diisocyanate (TDI), that is, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI). ), Mixed TDI of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 2,4′-diphenylmethane diisocyanate, liquid MDI such as crude MDI and carbodiimide-modified MDI, TDI And MDI mixtures. Among these, the use of TDI is preferable because a multilayer rubber having an excellent feel at impact can be obtained.

  In a preferred embodiment, the adhesive of the present invention further contains 50% by weight or less of a thermoplastic resin having a hardness (Shore A) of 50 or less. According to such a configuration, an adhesive for multilayer rubber having a better feel at impact can be obtained. As the thermoplastic resin having a hardness (Shore A) of 50 or less, EVA resin is preferable. If the added amount of the thermoplastic resin having a hardness (Shore A) of 50 or less exceeds 50% by weight, the viscosity of the adhesive becomes too high and the workability is lowered. The addition amount of the thermoplastic resin is more preferably 40 parts by weight or less. The hardness of the thermoplastic resin is preferably 10 or more, and more preferably 15 or more.

  The method for producing a rubber sheet / sponge sheet laminate according to the present invention includes an adhesive application step in which an adhesive is applied to at least the adhesive surfaces of the rubber sheet and the sponge sheet, and an adhesive that laminates the rubber sheet and the sponge sheet to which the adhesive is applied. And a curing step of curing the adhesive to form a rubber / sponge laminate, and reacting a polyol compound containing 50% by weight or more of a hydrocarbon-based polyol compound as an adhesive with an aromatic polyisocyanate compound. The adhesive for table tennis racket multilayer rubber containing the isocyanate group-containing prepolymer obtained in this manner is used.

  In the adhesive application step, the adhesive is applied to both the rubber sheet surface and the sponge sheet surface. The rubber sheet has a projecting surface and a flat surface. When the player's preference is to attach the projecting surface to the sponge sheet to make the ball striking surface flat, or to bond the flat surface to the sponge sheet and make the ball striking surface a projecting surface There is. The method for applying the adhesive is not particularly limited, and brush coating, coater coating, and the like are possible. However, it is preferable to use a coater such as a roll coater or a reverse roll coater because coating can be performed quickly and uniformly.

  In the bonding step, the adhesive-coated surfaces of the rubber sheet and the sponge sheet are bonded together. Although the bonding method is not particularly limited, it is preferable to press the whole with a uniform pressure, and press using a press or a roll is preferable. In particular, pressure bonding with a roll is preferable because continuous processing is possible.

  The curing step is a step of reactively curing the adhesive. The adhesive has NCO groups and is reactively cured by moisture in the air. The conditions for the curing step are not particularly limited, but when the temperature is low, the reaction slows down and it takes time to produce the laminate. The curing temperature is preferably 10 ° C. or higher. The humidity is preferably moderately high, is 40% or higher, more preferably 50% or higher, and may be humidified. In order to raise humidity, it is preferable to perform a hardening process in the chamber which adjusted temperature and humidity.

  In the above production method, it is a preferred embodiment to provide a degreasing step for degreasing at least a rubber sheet, preferably both a rubber sheet and a sponge sheet, before the adhesive application step. The rubber sheet may have a release agent attached at the time of molding, and the sponge sheet may have an oil component in the air or a manufacturer's oil component attached in the manufacturing process. The degreasing process can obtain better adhesive force by removing these release agents and oils. For degreasing, it is preferable to use an organic solvent that does not easily penetrate rubber and has high volatility, and preferably uses acetone, MEK, ethyl acetate, or the like.

  After the degreasing step, it is preferable to further provide a primer treatment step for primer treatment on the adhesive surface of the rubber sheet and the sponge sheet. By providing such a primer treatment step, stronger adhesion can be reliably performed.

  In the primer treatment step, the primer is applied to both the rubber sheet surface and the sponge sheet surface and dried. As the primer, a known or commercially available primer for vulcanized rubber can be used. As a known primer, a primer based on a polyester obtained by polycondensation of a polyvalent carboxylic acid component containing an aromatic polycarboxylic acid monomer and a polyhydric alcohol component (Japanese Patent Laid-Open No. 10-273581), Examples include halogen donor solutions such as trichloroisocyanuric acid and N, N-dichlorobenzenesulfonamide (Japanese Patent Publication No. 2003-521547).

  FIG. 1 shows an enlarged part of a cross section of the multilayer rubber of the present invention. The multi-layer rubber 10 in FIG. 1A is obtained by bonding the flat surface of the rubber sheet 12 to the sponge sheet 14 through a layer of the adhesive 16 to form a ball striking surface as shown in FIG. In the multi-layer rubber, the projecting surface of the rubber sheet 12 is bonded to the sponge sheet 14 via a layer of adhesive 16 to make the hitting surface flat. Both rubber sheets and sponge sheets are commercially available.

Example 1
<Manufacture of adhesives>
Hydroxyl-terminated liquid polybutadiene polyol R-45HT (Idemitsu Petrochemicals: molecular weight 2800, hydroxyl value 47 mg KOH / g) and an adhesive containing an isocyanate group-terminated prepolymer by heat-reacting TDI having an NCO / OH equivalent ratio of 4 (Prepolymer content of about 85% by weight) was obtained.

<Manufacture of multi-layer rubber>
The surface of the commercially available rubber sheet and sponge sheet to be bonded was degreased with acetone, and the above adhesive was applied with a roll coater so that the basis weight was 15 g / m ² . The adhesive coated surfaces of the rubber sheet and the sponge sheet were put together and pressed through a roll, then cured for 2 days in a chamber at a temperature of 30 ° C. and a relative humidity of 65%, and left for 5 days.

<Evaluation>
About the obtained multilayer rubber, the adhesiveness between the rubber sheet / sponge sheet and the multilayer rubber were bonded to a blade using a commercially available adhesive to form a table tennis racket, and the feel at impact was evaluated. The obtained multi-layer rubber had sufficient adhesive strength, and when it peeled, material destruction occurred. In addition, the table tennis racket in which this multi-layer rubber was bonded to the blade was also excellent in feel at impact as evaluated by all Japanese class table tennis players. The same adhesive strength and feel at impact were obtained even when the manufacturer / variety of rubber sheet / sponge sheet was changed. Even when a primer mainly composed of commercially available trichloroisocyanuric acid was applied to the adhesive surface of the rubber sheet and the sponge sheet before the adhesive application step, excellent adhesiveness was obtained in the same manner.

(Example 2)
30% by weight of EVA resin EV45LX (Mitsui Dupont Polychemical; Shore A hardness = 31) was added to and mixed with the isocyanate group-terminated prepolymer produced in Example 1 to prepare an adhesive.

<Manufacture of multi-layer rubber>
Using the above adhesive, bonding was performed in the same manner as in Example 1 to produce a multilayer rubber.
<Evaluation>
About the obtained multilayer rubber, the adhesiveness between the rubber sheet / sponge sheet and the multilayer rubber were bonded to a blade using a commercially available adhesive to form a table tennis racket, and the feel at impact was evaluated. The obtained multi-layer rubber had sufficient adhesive strength, and when it peeled, material destruction occurred. In addition, the table tennis racket in which this multi-layer rubber was bonded to the blade was also excellent in feel at impact as evaluated by all Japanese class table tennis players.

(Example 3)
Hydroxyl-terminated liquid polybutadiene polyol R-45HT (Idemitsu Petrochemical: molecular weight 2800, hydroxyl value 47 mgKOH / g) and mixed polyol compound of polypropylene glycol (molecular weight 2000, hydroxyl value 56 mgKOH / g) (liquid polybutadiene polyol 70% by weight) Then, TDI having an NCO / OH equivalent ratio of 4 was heated to obtain an adhesive (prepolymer content: about 84% by weight) containing an isocyanate group-terminated prepolymer.

<Manufacture of multi-layer rubber>
Using the above adhesive, bonding was performed in the same manner as in Example 1 to produce a multilayer rubber.
<Evaluation>
About the obtained multilayer rubber, the adhesiveness between the rubber sheet / sponge sheet and the multilayer rubber were bonded to a blade using a commercially available adhesive to form a table tennis racket, and the feel at impact was evaluated. The obtained multi-layer rubber had sufficient adhesive strength, and when it peeled, material destruction occurred. In addition, the table tennis racket in which this multi-layer rubber was bonded to the blade was also excellent in feel at impact as evaluated by all Japanese class table tennis players.

Sectional drawing which showed the structure of the multi-layer rubber (rubber sheet / sponge sheet laminate) used for the table tennis racket

10 Multi-layer rubber 12 Rubber sheet 14 Sponge sheet

Claims (7)

A method for producing a multilayer rubber (rubber sheet / sponge sheet laminate) in which a rubber sheet of a table tennis racket and a sponge sheet are laminated,
An adhesive application step of applying an adhesive to at least an adhesive surface of the rubber sheet and the sponge sheet, an adhesive step of adhesively laminating the rubber sheet and the sponge sheet applied with the adhesive, and a multilayer rubber by curing the adhesive A curing step to
The adhesive viewed contains an isocyanate group-containing prepolymer obtained by reacting a polyol compound and an aromatic polyisocyanate compound containing a hydrocarbon-based polyol compound than 50 wt%, table tennis rackets double layer rubber having an isocyanate group A method for producing a multilayer rubber, which is an adhesive.
  The method for producing a multilayer rubber according to claim 1, wherein the adhesive further contains 50% by weight or less of a thermoplastic resin having a hardness (Shore A) of 50 or less.   Furthermore, the manufacturing method of the multilayer rubber | gum of Claim 1 or 2 which has a degreasing process of degreasing the adhesion surface of the said rubber sheet and sponge sheet | seat before the said adhesive agent application process.   5. The method for producing a multilayer rubber according to claim 4, further comprising a primer treatment step of primer-treating the adhesive surfaces of the rubber sheet and the sponge sheet after the degreasing step. A multi-layer rubber which is bonded to a blade to form a table tennis racket, and is obtained by reacting a rubber sheet and a sponge sheet with a polyol compound containing 50% by weight or more of a hydrocarbon-based polyol compound and an aromatic polyisocyanate compound. It is seen containing an isocyanate group-containing prepolymer, multilayer rubber for table tennis racket adhered by curing the adhesive having an isocyanate group.
An adhesive that bonds a rubber sheet of a table tennis racket and a sponge sheet to form a multilayer rubber,
The hydrocarbon polyol compound by reacting a polyol compound and an aromatic polyisocyanate compound containing more than 50 wt% seen containing an isocyanate group-containing prepolymer obtained, table tennis racket multilayer adhesive for rubber having an isocyanate group.
  The adhesive for table tennis racket multilayer rubber according to claim 6, wherein the adhesive further contains 50% by weight or less of a thermoplastic resin having a hardness (Shore A) of 50 or less.

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