JP5506256B2 - Table tennis rubber manufacturing method and table tennis rubber - Google Patents

Description

  The present invention relates to an aqueous adhesive for bonding a table tennis rubber sheet not containing a volatile organic compound and a sponge, and a method for producing table tennis rubber using the aqueous adhesive.

  Conventionally, as a table tennis rubber adhesive for bonding table rubber and blades of table tennis rackets, and an adhesive for bonding table tennis rubber sheets and sponges, synthetic rubbers such as natural rubber and chloroprene rubber are aromatic hydrocarbons such as toluene. A solution in a volatile organic compound (hereinafter sometimes referred to as VOC) such as a solvent or a ketone solvent such as acetone has been used.

  In particular, table tennis rubber adhesives that bond rubber and blades may improve the performance of table tennis rubber, such as the rotational force applied to the ball and the ball, and control performance, depending on the type of VOC used. VOC is contained in the adhesive for table tennis rubber that is favored by table tennis players all over the world including athletes.

  However, because VOCs are harmful to the human body, the International Table Tennis Federation (hereinafter abbreviated as ITTF) has stated in the Olympic Charter 21 “Products that pollute the environment that are considered harmful or toxic to humanity are not allowed”. In view of this, the Board of Directors has decided to prohibit the use of adhesives that are harmful to the human body after September 1, 2008.

  However, there is no official standard for VOC standards from ITTF. Also, according to the rules, the contents defined in Chapter 2, Article 4, Paragraph 7 (Non-Patent Document 1) were only decided on April 27, 2008. However, the ITTF's goal is to “zero the organic solvent emitted from the racket (the one with the rubber attached)”. In order to overcome such restrictions, the present applicants developed an aqueous table tennis rubber adhesive that does not contain VOC (Patent Document 1).

  Also, in international competitions, players' rackets are strictly inspected by dedicated racket inspection machines. In order to clear the inspection with the racket inspection machine, athletes now use water-based adhesives that do not contain VOCs for bonding the blade and rubber.

  However, the VOC contained in the adhesive that bonds the sponge and the sheet used by the racket manufacturer when manufacturing the rubber may react to the racket inspection machine.

  ITTF's intention is to achieve zero tolerance for VOCs emitted from rackets as described above. Also, according to Rule No. 2.4.7, there is a view that “table tennis rubber must have stable physical properties and organic solvents emitted from rubber must be suppressed”.

  At present, when using a new rubber, it is thought that VOCs that may remain on the rubber can be removed by removing the rubber from the packaging material, exposing it to air for 72 hours, and then adhering it to the racket. Yes. However, there is actually a problem with the preparation of players before the match, and not all players are able to do this, and this is not a fundamental solution.

  Further, natural rubber or chloroprene rubber latex can be considered as an adhesive containing no VOC, but it is not preferable because of poor adhesion and shot feeling.

JP 2007-2848573 A

ITTF Handbook 2008/2009, 2.04.07

  The problem to be solved by the present invention is to provide a water-based adhesive for bonding table tennis rubber sheets and sponges substantially free of VOCs in order to more completely meet ITTF regulations.

The present invention for solving the above problems is as follows.
(1) A water-based adhesive for laminating a table tennis rubber sheet and a sponge, which does not contain a volatile organic compound, comprising an aqueous polyurethane resin dispersion.
(2) The aqueous adhesive for laminating a table tennis rubber sheet and a sponge according to claim 1, further comprising a styrene-butadiene copolymer latex.
(3) The water-based adhesive for laminating a table tennis rubber sheet and sponge according to item 2, wherein the styrene-butadiene copolymer latex has a gel fraction of 30 to 100%.
(4) The water-based adhesive for bonding table tennis and the sponge of any one of items 1 to 3 is applied to the sheet and / or sponge, and the sheet and the sponge are bonded together and dried. A table tennis rubber manufacturing method.

  Since the water-based adhesive for laminating a table tennis rubber sheet and a sponge of the present invention does not substantially contain VOCs, the ITTF regulations can be cleared. In addition, the water-based adhesive of the present invention can provide a table tennis rubber having a hit feeling equivalent to that of a conventional adhesive containing VOC.

It is a schematic cross section of table tennis rubber.

  FIG. 1 is a schematic cross-sectional view of a table tennis rubber. As shown in FIG. 1, the table tennis rubber is a laminate of the sponge 1 and the sheet 2. FIG. 1 is a schematic cross-sectional view of a so-called back soft rubber obtained by laminating a sheet surface with ribs and a sponge.

  The water-based adhesive for bonding a table tennis rubber sheet and a sponge of the present invention is characterized by comprising an aqueous polyurethane resin dispersion and does not contain VOCs. In the present invention, “not containing VOC” means that VOC is substantially not included, and it means a concentration below that which does not react to the racket inspection machine.

The polyurethane resin aqueous dispersion of the present invention is a polyurethane resin dispersed or emulsified in an aqueous medium.
The polyurethane resin aqueous dispersion used in the present invention is not particularly limited as long as the polyurethane resin is dispersed or emulsified in an aqueous medium. For example, (1) polyisocyanate, polyol and carboxyl group-containing polyol are used. The polyurethane prepolymer containing carboxyl groups obtained by the reaction is neutralized with a tertiary amine and emulsified and dispersed in water and / or emulsified and dispersed, and then polymerized with a chain extender such as polyamine. The obtained polyurethane resin aqueous dispersion, (2) the terminal isocyanate prepolymer obtained by reacting polyisocyanate and polyol is emulsified and dispersed in water in the presence of a surfactant and / or emulsified and dispersed, and then polyamine, etc. Polyurea obtained by increasing the molecular weight with a chain extender (3) The polyurethane prepolymer described in (1) and (2) above is synthesized in the presence of an organic solvent and emulsified and dispersed, and then the organic solvent is removed by a known method as necessary. Examples thereof include an aqueous polyurethane resin dispersion obtained by the method.

  As the polyisocyanate, any of the polyisocyanates conventionally used in the production of ordinary polyurethane can be used. One or two of alicyclic diisocyanate, aliphatic diisocyanate and aromatic diisocyanate having a molecular weight of 500 or less can be used. More than species are preferably used. Examples of these include hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, norbornene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, p. -Phenylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, 1,5-naphthylene diisocyanate and the like can be mentioned, and one or more of these can be used. Further, a tri- or higher functional polyisocyanate such as hexamethylene diisocyanate trimer may be used in combination.

  Examples of the polyol include polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (methyltetramethylene) glycol; polybutylene adipate diol, polybutylene sebacate diol, polyhexamethylene adipate diol, poly (3- Polyester polyols such as methyl-1,5-pentylene adipate) diol, poly (3-methyl-1,5-pentylene sebacate) diol, polycaprolactone diol, poly (β-methyl-δ-valerolactone) diol; Polycarbonate polyols such as polyhexamethylene carbonate diol and poly (3-methyl-1,5-pentylene carbonate) diol; polyester polycarbonate polyols; Known polyols such as polyolefin polyols such as reethylene polyol, polypropylene polyol, polyisobutene polyol, polybutadiene polyol and hydrogenated product thereof, and polyisoprene polyol and hydrogenated product thereof can be mentioned, and the polyurethane resin is one kind of these polyols or Two or more types can be used.

  As the chain extender component, any of chain extenders conventionally used in the production of ordinary polyurethane can be used, but a molecular weight of 300 having two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule. The following low molecular weight compounds are preferably used. For example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-cyclohexanediol, bis- (β-hydroxyethyl) Diols such as terephthalate and xylylene glycol; triols such as trimethylolpropane; pentaols such as pentaerythritol; hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and Derivatives, diamines such as phenylenediamine, tolylenediamine, xylenediamine, adipic acid dihydrazide, isophthalic acid dihydrazide; aminoethyl alcohol, aminopropyl Amino alcohols such as alcohol, N- (2-aminoethyl) ethanolamine; γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltri Examples include alkoxysilyl group-containing amines such as methoxysilane and N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, and one or more of these can be used. Moreover, you may use together monoamine compounds, such as n-butylamine, 4-aminobutanoic acid, and 6-aminohexanoic acid, with a polyamine compound more than bifunctional at the time of chain | strand extension reaction.

  The polyurethane resin preferably has a neutralized carboxyl group in the polyurethane resin skeleton so as to be emulsified and dispersed or dissolved in water. The introduction of the neutralized carboxyl group into the polyurethane resin skeleton is performed by using a compound having a carboxyl group or a salt thereof and containing one or more active hydrogen atoms such as a hydroxyl group or an amino group in the polyurethane-forming reaction. This is achieved by neutralizing with a basic substance such as a tertiary amine or alkali metal hydroxide, if necessary. Examples of such compounds include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, and the like. Furthermore, polyester polyols or polyester polycarbonate polyols obtained by copolymerizing the above compounds can also be used. Among these, a polyurethane prepolymer is produced using 2,2-dimethylolpropionic acid or 2,2-dimethylolbutyric acid, and after completion of the prepolymer reaction or when the prepolymer is emulsified in water, trimethylamine, triethylamine, N, A method of converting to a carboxylate by adding a basic substance such as N-dimethylethanolamine, N, N-diethylethanolamine, N-methyldiethanolamine, sodium hydroxide or potassium hydroxide is preferred.

  Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetates such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; Amides such as dimethylformamide and N-methylpyrrolidone; and halogen-containing hydrocarbons such as chloroform and methylene chloride. These can be used alone or in combination. Especially, it is preferable to use the organic solvent which has a boiling point of 150 degrees C or less, and it is more preferable to use acetone, methyl ethyl ketone, and ethyl acetate with high solubility with respect to a polyurethane resin.

  When manufacturing the said polyurethane resin, a urethanization catalyst can be used as needed. Examples of urethanization catalysts include nitrogen-containing compounds such as triethylamine, triethylenediamine, and N-methylmorpholine, metal salts such as potassium acetate, zinc stearate, and tin octylate, and organometallic compounds such as dibutyltin dilaurate. can do.

In addition, the surfactant that can be used when the polyurethane resin aqueous dispersion is produced is not particularly limited, and an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and the like are used. However, it is preferable to use an anionic surfactant or a nonionic surfactant from the viewpoint of preventing the polyurethane resin from aggregating.
Examples of the anionic surfactant include alkyl benzene sulfonate, polyoxyethylene alkyl phenyl sulfonate, polyoxyethylene alkyl diphenyl ether sulfonate, alkyl diphenyl ether disulfonate, and dialkyl ester sulfonate succinate. be able to.

  As the nonionic surfactant, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene diphenyl ether, polyoxyethylene-polyoxypropylene block copolymer, acetylenic diol surfactant and the like are used. be able to.

  In the present invention, in addition to the above-described surfactant, a fluorosurfactant, a silicone-based surfactant, or a surfactant having a polymerizable unsaturated group generally called a reactive emulsifier is used. You can also.

  Moreover, in this invention, you may use various dispersion stabilizers in the range which does not inhibit the effect of this invention. Examples of the dispersion stabilizer include polyvinyl alcohol, fiber ether, starch, maleated polybutadiene, maleated alkyd resin, water-soluble polyester resin, water-soluble polyamide resin, water-soluble polyurethane resin, water-soluble acrylic resin, and the like. It can be used alone or in combination of two or more. These may be added and used during the production of the polyurethane resin, or may be mixed after completion of the reaction.

In the water-based adhesive for laminating a table tennis rubber sheet and sponge according to the present invention, in addition to the polyurethane resin aqueous dispersion described above, a styrene-butadiene copolymer latex is used in combination to further improve adhesion and feel at impact. can do.
As is well known, the styrene-butadiene copolymer latex is a latex made of a copolymer of an aromatic vinyl monomer and a conjugated diene monomer. Various conventionally known styrene-butadiene copolymer latexes are appropriately used.

  As such styrene-butadiene copolymer latex, typically, 10 to 70% by weight of an aromatic vinyl monomer, 10 to 70% by weight of a conjugated diene monomer, 0.5% Examples thereof include those obtained by emulsion polymerization of 10 to 10% by weight of ethylenically unsaturated carboxylic acid monomers and 0 to 50% by weight of other vinyl monomers copolymerizable therewith. Furthermore, it is possible to use a latex containing a partially crosslinked polymer. Further, among such styrene-butadiene copolymer latexes, those having a gel fraction of about 30 to 100% can be suitably employed. Of course, such styrene-butadiene copolymer latexes can be used. It goes without saying that the present invention is not limited to these.

  In addition, examples of the aromatic vinyl monomer used for the production of the above styrene-butadiene copolymer latex include styrene and vinyl toluene, while examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2-ethyl-1,3-butadiene, chloroprene, and the like. Examples of the ethylenically unsaturated carboxylic acid monomer include itaconic acid, fumaric acid, maleic acid, acrylic acid, methacrylic acid, and other vinyl monomers that can be copolymerized. Exemplify vinyl cyanides such as acrylonitrile and methacrylonitrile; (meth) acrylic acid esters such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, etc. I can do it.

  The styrene-butadiene copolymer latex preferably has a gel fraction of 30 to 100%, more preferably 40 to 90%. The gel fraction is the gel fraction of the styrene-butadiene copolymer latex, the weight ratio of the cured film of the sufficiently dried styrene-butadiene copolymer latex to the insoluble content of the cured film immersed in acetone for 8 hours. .

  The blending ratio of the polyurethane resin aqueous dispersion and the styrene-butadiene copolymer latex is as follows: polyurethane resin aqueous dispersion: styrene-butadiene copolymer latex = 95: 5 to 5:95 wt% per 100 wt% of the aqueous adhesive. Preferably, it may be appropriately selected within the range of 80:20 to 20: 80% by weight, more preferably 60:40 to 40: 60% by weight.

  In the aqueous adhesive for bonding a table tennis rubber sheet and a sponge of the present invention, it is preferable to adjust the viscosity according to various coating methods when applied to the sponge, and a thickener is used as the viscosity adjusting method. It is preferable to do.

As a thickener, cellulose derivatives such as HEC (hydroxyethylcellulose), MC (methylcellulose), CMC (carboxymethylcellulose), polyacrylate, polyacrylate, PVP (polyvinylpyrrolidone), urethane-based, polyether-based Associative thickeners and the like.
These thickeners may be used alone or in combination of two or more.

  The thickener may be used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the aqueous adhesive.

  In addition, acrylic emulsion, vinyl acetate emulsion, etc. can be added within a range that does not affect the adhesion.

  The water-based adhesive for laminating a table tennis rubber sheet and sponge of the present invention has a nonvolatile content of 10 to 70%, preferably 30 to 50%, and a viscosity of 20 to 50000 mPa · s, preferably 100 to 10000 mPa · s. May be used.

  As a method of laminating a sheet and a sponge in the aqueous adhesive of the present invention, 3 to 5 grams of the aqueous adhesive of the present invention was applied to a sponge of about 30 cm square with a roll coater, and the sheet was adhered immediately after that. It shall be dried under reduced pressure for 12 to 72 hours by sandwiching it between plates. The table tennis rubber is a single rubber sheet only, a soft rubber back with a tab and a sponge, and a flat surface and a sponge so that the tab has a ball striking surface. Although there are three types of soft rubber, the water-based adhesive of the present invention can be used for the production of a back soft rubber and a front soft rubber. In order to produce the back soft rubber, the aqueous adhesive of the present invention may be applied to the sponge and bonded to the surface with the tab of the sheet. To produce the front soft rubber, the aqueous adhesive of the present invention is applied to the sponge. Apply and stick to the flat surface of the sheet.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Production Example 1
Production method of aqueous polyurethane resin dispersion In a four-necked flask equipped with a stirrer, Dimroth cooler, nitrogen inlet tube and thermometer, 100 parts by weight of polypropylene glycol having a molecular weight of 2,000 (Diol-2000, manufactured by Mitsui Chemicals, Inc.) The dehydration was performed at 110 ° C. under a nitrogen stream, and after dehydration, the mixture was cooled to 60 ° C. Thereafter, 1.6 parts by weight of 2,2-dimethylolpropionic acid, 17.5 parts by weight of isophorone diisocyanate (manufactured by Huls, VESTANT IPDI) and 70 parts by weight of acetone were sequentially added, and NCO% was 70 to 90 ° C. The reaction was continued until 1.22. Then, it cooled to 40 degrees C or less, added 1.2 weight part of triethylamine, neutralized, and prepared the polyurethane prepolymer solution.

  While stirring the prepared polyurethane prepolymer, 281 parts by weight of distilled water was gradually added to obtain a milky white polyurethane prepolymer aqueous dispersion. Thereafter, 1.5 parts by weight of N- (2-aminoethyl) ethanolamine (manufactured by Nippon Emulsifier Co., Ltd., amino alcohol EA) was immediately added dropwise to cause a chain elongation reaction. In this extension reaction, the reaction temperature was adjusted to 30 ° C. or lower. Subsequently, stirring was continued at room temperature for 1 hour, and then acetone was removed at 40 to 50 ° C. under reduced pressure to obtain a polyurethane resin aqueous dispersion (A) having a nonvolatile content of 30% and a viscosity of 50 mPa · s.

Production Example 2
Production method of acrylic emulsion In a container, 50 parts by weight of ion exchange water, 5 parts by weight of sodium dodecyl sulfate, 1.5 parts by weight of acrylic acid, 52 parts by weight of 2-ethylhexyl acrylate, 46.5 parts by weight of methyl methacrylate, 10% excess A monomer emulsion was prepared by weighing and stirring 2.0 parts by weight of an aqueous ammonium sulfate solution. A four-necked flask equipped with a stirrer, a Dimroth cooler, a nitrogen inlet tube and a thermometer was charged with 50 parts by weight of ion-exchanged water, and the internal temperature was raised to 75 ° C. while stirring. And 0.5 part by weight of 10% aqueous ammonium persulfate solution. The remaining monomer emulsion was dropped at the same temperature, and a polymerization reaction was performed for 3 hours. The polymerization reaction was carried out after 1 hour while maintaining the internal temperature. After completion of the post-polymerization reaction, the mixture was cooled to room temperature and neutralized by adding 3 parts by weight of a 25% aqueous ammonia solution to obtain an acrylic emulsion (B) having a viscosity of 200 mPa · s and a nonvolatile content of 50.7%.

Examples 1-3
Polyurethane resin aqueous dispersion (A) prepared in Production Example 1 and styrene-butadiene copolymer latex (trade name “L7850”, trade name “A7269”, manufactured by Asahi Kasei Chemicals Co., Ltd.) at the ratio shown in Table 1. Blended (blending amount shown in Table 1 indicates parts by weight), thickener (polyacrylate emulsion, trade name “Primal ASE60”, manufactured by Rohm & Haas Co., Ltd.) was added and stirred for 30 minutes to be aqueous An adhesive was prepared. The gel fraction of “L7850” was 34%, and the gel fraction of “A7269” was 50%.

Comparative Example 1
0.5 parts by weight of Primal ASE60 was added to 100 parts by weight of the acrylic emulsion (B) prepared in Production Example 2 and stirred for 30 minutes to prepare an acrylic emulsion adhesive (B-1).

Comparative Example 2
100 parts by weight of chloroprene latex (trade name “Skyprene Latex SL-360”, manufactured by Tosoh Corporation, nonvolatile content of about 52%) and urethane associative thickener (polyurethane resin, trade name Adecanol UH-420, ADEKA) 0.5 parts by weight was added and stirred for 30 minutes to prepare a chloroprene latex adhesive (C-1).

Comparative Example 3
A chloroprene rubber solvent type adhesive was prepared by blending chloroprene rubber with 72% toluene and 8.9% methyl ethyl ketone.

  The aqueous adhesives of Examples 1 to 3 and the adhesives of Comparative Examples 1 to 3 were applied to the surface of the sponge with a roll coater, and the sheet and the sponge were bonded together. The sponge and the sheet are based on natural rubber obtained by vulcanizing sulfur, and the sponge and the sheet used in the table tennis rubber “Blythe” of Tamas Co., Ltd. were used.

Thereafter, it was further dried for 12 hours in an environment of slightly reduced pressure at 30 ° C. to prepare a table tennis rubber test body. Each evaluation was measured as follows.
<Adhesiveness>
Evaluation ◎ ・ ・ ・ If you try to peel, the sheet or sponge will be destroyed.
○ ・ ・ ・ Partial destruction of the sheet or sponge when peeling is attempted.
X: Not bonded.

<Hit feel>
The racket was created using the table tennis rubber which bonded together using the adhesive agent of an Example and a comparative example, and the good hit feeling at the time of using was evaluated.
Evaluation ◎ ... Good hit feeling.
○ ... A hit feeling is preferable.
X: The hit feeling is not preferable.

<Workability>
The applicability when the adhesive was applied to the sponge with a roll coater was evaluated as workability.
Evaluation ○: Can be applied satisfactorily.
X: Cannot be applied.

  Table 1 shows the composition of the aqueous adhesives of Examples 1 to 3 and the results of evaluation. The evaluation results of Comparative Examples 1 to 3 are shown in Table 2.

  As is apparent from the results shown in Tables 1 and 2, the water-based adhesive of the present invention has good adhesiveness even though it does not substantially contain VOC, and the shot feel includes conventional VOC. It was the same or more than the table tennis rubber manufactured with the chloroprene rubber solvent-type adhesive (Comparative Example 3). Moreover, the table tennis rubber manufactured with the acrylic emulsion adhesive (Comparative Example 1) and the chloroprene latex adhesive (Comparative Example 2) was inferior in adhesiveness and feel at impact.

 Rubber prepared with the water-based adhesive of the present invention of Examples 1 to 3 and the conventional chloroprene rubber solvent-based adhesive of Comparative Example 3 was subjected to VOC using a racket inspection machine (trade name “ENEZ”, manufactured by WASSING). The presence or absence was judged. The results are shown in Table 3.

Racket inspection machine criteria
OK ... The racket inspection machine does not respond (no VOC).
NG: The racket inspection machine reacts (with VOC).

  As is clear from the results shown in Table 3, the table tennis rubber prepared with the aqueous adhesive of the present invention did not react with the racket inspection machine and could be evaluated as substantially free of VOC.

  The water-based adhesive for bonding table tennis rubber sheets and sponges of the present invention does not substantially contain VOCs, so it can satisfy the VOC regulations of ITTF, and can provide a shot feel of adhesives containing conventional VOCs. There is no loss.

1: Sponge 2: Sheet

Claims (4)

A water-based adhesive for bonding table tennis rubber and sponge, which does not contain volatile organic compounds, made of polyurethane resin aqueous dispersion, is applied to the sheet and / or sponge, and the sheet and sponge are bonded together and dried. A table tennis rubber manufacturing method. The method for producing table tennis rubber according to claim 1, wherein a styrene-butadiene copolymer latex is further added to the water-based adhesive. The method for producing table tennis rubber according to claim 2, wherein the styrene-butadiene copolymer latex has a gel fraction of 30 to 100%. A table tennis rubber comprising a polyurethane resin aqueous dispersion and a sheet and sponge bonded together with an aqueous adhesive containing no volatile organic compound.

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