JP2000167088A - String for racket and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly fix a filament to a depth part in a safe and simple manufacturing process and improve durability and usage feeling, by fixing the filament with a specific visible-radiation-hardening-type adhesive composition, in a racket string using the synthetic resin made filament. SOLUTION: In a racket string using a synthetic resin made filament, the filament is fixed using a visible-radiation-hardening-type adhesive composition containing a visible-radiation-polimerization starting system composed of combination of dialkylaminobenzylidene derivative as an electron do nor and diphenyl iodonium salt as an electron acceptor. Here, the dialkylaminobenzylidene derivative is selected from a group composed of 2,6-bis(4'-dimetylaminobenzylidene) cyclohexanone, 2,6-bis(4'-dimetylaminobenzylidene) 4-methylcyclohexanone, and their mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a string used for a racket such as tennis, badminton, and squash.

[0002]

2. Description of the Related Art Conventionally, as a racket string,
Natural materials such as sheep intestine and whale muscle have been used. These natural strings have appropriate resilience and elasticity, give the player a pleasant feel at impact, and have excellent performances such as high impact absorption at impact. However, these natural strings have the disadvantage that they are poor in durability, especially in moisture resistance, and have a short life. Therefore, a synthetic fiber string having excellent durability has been proposed by using, for example, a filament made of a synthetic resin such as polyamide, and this is becoming the mainstream of strings for rackets.

As described above, the performance required of a racket string includes resilience and shot feeling in addition to durability. In the case of a synthetic fiber string, these properties are determined by the material of the filament itself. It is strongly affected not only by the shape and shape, but also by the adhesive used to fix and ply twist the monofilament or multifilament during manufacture. For this reason, various adhesives have been proposed for producing synthetic fiber strings.

[0004] As such an adhesive, for example, a resin obtained by dissolving a nylon resin in a solvent such as phenol and diluting it with a solvent such as dichloroethane as necessary is generally used. It is not always preferable from the viewpoint of environmental hygiene such as causing burns when coming into contact with the skin. Recently, urethane resin, acrylic resin,
Resins having rubber elasticity such as silicone resins have been used. Of these, urethane-based resins are attracting attention as having high flexibility and having excellent characteristics for application to strings. In particular, when an ultraviolet curable adhesive containing polyurethane acrylate as a main component is used, the resin has an advantage that the resin can be rapidly cured by irradiation with ultraviolet light, and the obtained string has a soft feel at impact, It has been reported that it has excellent resilience and has favorable performance (Japanese Patent Publication No. Hei 4-23551). However, the ultraviolet curable adhesive has various problems as described below, and it is not always satisfactory to produce a synthetic fiber string using the adhesive.

[0005]

The photocurable adhesive is an adhesive based on a photopolymerizable prepolymer, a photopolymerizable monomer and a photoinitiator, and other additives may be added as needed. Prepared by Upon curing
The photopolymerization initiator receives light rays, absorbs light energy, generates primary radicals necessary for the initiation of polymerization,
The photopolymerizable prepolymer and the photopolymerizable monomer polymerize to achieve curing.

An ultraviolet curing system uses ultraviolet light as a light source for polymerization, and is extremely industrially advantageous in that it can cure a resin quickly and in a short time by irradiation with ultraviolet light. Has been adopted in.

[0007] However, the system for ultraviolet curing has the following problems.

In general, a high-pressure mercury lamp or a metal halide lamp having a large output is used as an ultraviolet light source. A high-pressure mercury lamp is a discharge lamp in which high-purity mercury and a small amount of a rare gas are sealed inside a quartz glass arc tube.It is necessary to maintain a constant tube wall temperature in order to increase the generation efficiency of ultraviolet rays. is there. A metal halide lamp is a discharge lamp in which a metal halide compound is sealed. The lamp structure is almost the same as that of a high-pressure mercury lamp, but the generation efficiency of ultraviolet rays is improved. The control of the equipment to use these light sources is complicated and therefore expensive to maintain.

A system using a light source as described above may adversely affect the human body due to the generation of ozone, and often causes diseases such as dermatitis and ophthalmitis due to short-wavelength ultraviolet rays. It is necessary to consider safety such as danger.

[0010] The curability at the deep part of the irradiation object becomes extremely poor due to absorption and scattering of ultraviolet rays in the surface layer of the irradiation object. In order to solve this problem, a method of separately disposing an anaerobic resin adhesive inside the irradiation object has been proposed (Japanese Patent Application Laid-Open No. 9-241936). I can't say.

Since the cured string is stretched over a tennis racket or the like and is often used outdoors, it is generally desirable to impart weather resistance to the string.
However, when an ultraviolet curing system is used, if an ultraviolet absorber commonly used for imparting weather resistance is blended with the ultraviolet curing adhesive, the curing is hindered. Therefore, it is difficult to use a conventional light stabilizer.

There is a risk that the base material of the string (for example, reinforcing fibers or adhesive resin) may be damaged by the irradiation of the ultraviolet rays.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a string which can securely fix a filament to a deep portion by a safe and simple manufacturing process and has excellent durability and usability. I do.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a racket string using a synthetic resin filament, wherein the filament is fixed by a visible light curable adhesive composition. Features (Claim 1). Since this string uses a light source that emits visible light for the adhesive polymerization for fixing the filament, the control of the equipment is easy, the equipment cost and the maintenance cost of the equipment do not increase, and the string base material is not increased. Less likely to damage Further, there is no adverse effect on the human body and the environment at the time of manufacturing. Furthermore, since visible light has little absorption into the synthetic resin and scattering on the synthetic resin surface, the light reaches the deep part, and the adhesive can be sufficiently cured in a short time, and a string with excellent durability can be obtained. can get. Then, if necessary, an ultraviolet absorber may be blended to impart light resistance to the string without difficulty.

In this string, the visible light-curable adhesive composition comprises a visible light polymerization initiation system comprising a combination of a dialkylaminobenzylidene derivative as an electron donor and a diphenyliodonium salt as an electron acceptor. (Claim 2) is preferred. According to such a combination, the polymerization of the adhesive by visible light is carried out smoothly and sufficiently in a short time.

The dialkylaminobenzylidene derivative is composed of 2,6-bis (4'-dimethylaminobenzylidene) cyclohexanone, 2,6-bis (4'-dimethylaminobenzylidene) 4-methylcyclohexanone, and a mixture thereof. It may be selected from a group (claim 3).

Further, the present invention provides a method for producing a racket string using the above-mentioned synthetic resin filament, wherein the visible ray-curable adhesive composition is applied to the filament, and the filament is irradiated with visible light to form the visible ray-curable adhesive composition. The method includes a step of curing the adhesive composition (claim 4). By this method, a target string can be manufactured.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail.

In general, among electromagnetic waves, the wavelength is longer than X-rays (about 10 nm or more) and shorter than radio waves (about 0.1 mm).
) Are referred to as light rays, which are further divided into ultraviolet rays (about 10 to 380 nm) and visible rays (about 380 to 800 nm).
nm) and infrared rays (about 800 nm to 0.1 mm) (see Illumination Glossary).

In the present invention, in order to irradiate a visible light having a wavelength of about 380 to 800 nm upon curing of the adhesive, an incandescent lamp or a dedicated visible light fluorescent lamp having an output characteristic in a short wavelength visible portion is used. . In the visible light region, for example, 488 nm (argon laser), 633n
A laser beam having a spectral wavelength at m (helium-neon laser), 780 nm (semiconductor laser), or the like can also be used.

Since such visible light is hardly absorbed by the synthetic resin constituting the filament, it can not only achieve a sufficient hardening to a deep portion in a short time, but also has no adverse effect on the environment and the human body, and furthermore, has a light source. Maintenance is easy and economical.

The visible light-curable adhesive composition is basically the same as the conventionally known chemically polymerizable resin adhesive composition except that the initiation of polymerization is caused by the visible light, and its main component is Are visible light polymerization systems (visible light polymerization initiators and, preferably, visible light sensitizers), prepolymers, monomers and other additives. In order to enable or facilitate application of the composition to the filament by immersion or the like, a conventionally used solvent may be added, if necessary, so that the composition has an appropriate viscosity.

The most important element in the present invention is a visible light polymerization initiator which constitutes a visible light polymerization initiation system. Further, a visible light sensitizer is appropriately selected and blended to form an electron donor (donor) and It is effective to employ a suitable combination of electron acceptors (acceptors).

Most of the visible light polymerization initiation systems utilize a photooxidation-reduction system, and there are cases where a visible light sensitizer acts as an oxidizing agent and acts as a reducing agent. There are many.

As an example of a typical visible light polymerization initiator,
First, p-dialkylaminobenzylidene derivatives such as 2,6-bis (4′-dimethylaminobenzylidene) cyclohexanone and 2,6-bis (4′-dimethylaminobenzylidene) 4-methylcyclohexane, and 4,4′-bis ( Dimethylamino) benzophenone, and mixtures thereof. When these are used as a donor, a diphenyliodonium salt is preferably selected as a visible light sensitizer which is an acceptor for the donor. Further, a combination of 7-dialkylaminobenzo-α-pyrone and p-biphenylmethoxyamine salt as a donor and an acceptor in a visible light polymerization initiation system, and N
When a combination of -phenylglycine and a 7-hydroxy-α-pyrone derivative is selected, radicals are generated with high sensitivity by irradiation with visible light of 550 nm. In addition, examples of the compound serving as a donor of the visible light polymerization initiation system include:
1,4-diethylaminoanthraquinone, α-cyano-4- [2 (2
-Pyridyl) ether] methyl cinnamate, α-cyano [dimethylaminophenyl] methyl cinnamate, sodium toluenesulfonate, triethanolamine, merocyanines, porphyrins and the like. Examples of acceptors for these include chloromethyltriazine derivatives such as 2,4,6-tris (trichloromethyl) -S-triazine and 2-methyl4,6- (trichloromethyl) -S-triazine; O, O- Thiazine dyes such as t-butyl diperoxyphthalate, hexaallyldiimidazolyl and methylene blue; xanthene dyes such as eosin and fluorescein; and acridine dyes such as porphyrin and riboflavin. The above compounds are merely examples, and the compounds usable in the present invention are not limited to these.

These visible light polymerization initiation systems containing a visible light polymerization agent and preferably a visible light sensitizer are used in the visible light curable adhesive composition in an amount of 0.5 to 10% by weight, preferably 1 to 10% by weight. 5% by weight. If the amount is too small, it is difficult to initiate polymerization by visible light. If the amount is too large, improvement in visible light sensitivity cannot be expected, and physical properties are rather deteriorated. When a sensitizer is compounded, the sensitizer / polymerization initiator compounding weight ratio is preferably set in the range of 1 to 0.5.

By appropriately selecting such a visible light polymerization initiation system, photopolymerization can be sufficiently promoted by visible light having a wavelength of about 380 to 800 nm.

The prepolymer to be incorporated in the visible light curable adhesive composition of the present invention includes polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligoacrylate, and the like.
Alkyd resin acrylate, polyol acrylate,
Spirane resin acrylate, silicone resin acrylate and the like.

The content of the prepolymer in the visible light-curable adhesive composition is 30 to 70% by weight, preferably 40 to 70% by weight.
It is good to be 60% by weight. If the amount is too small, proper physical performance such as adhesiveness cannot be obtained, and if the amount is too large, the viscosity of the adhesive composition increases, which causes a problem in workability of the string.

Examples of the visible light-polymerizable monomer include acrylic acid esters such as 1,3-butanediol acrylate and trimethylolpropane triacrylate. Such acrylates are crosslinked in a short time by irradiation with visible light, and adhesiveness with nylon or the like, which is a polyamide synthetic fiber constituting the filament of the string, is obtained.

The content of this visible light polymerizable monomer in the visible light curable adhesive composition is 25 to 65% by weight,
Preferably, the content is 30 to 50% by weight. If the amount is too small, the viscosity of the adhesive composition becomes high, causing a problem in the processability of the string. If the amount is too large, the properties of the polymerizable prepolymer are lost, and the physical properties of the string are reduced.

The visible light curable adhesive composition of the present invention comprises an ultraviolet absorber, a light stabilizer, a polymerization accelerator, an auxiliary, a stabilizer, a viscosity modifier, an antioxidant, a colorant, a water repellent, An appropriate amount of an antifouling agent may be added.

As the synthetic fibrous filament used in the string of the present invention, 6-
Nylon, 6,6-nylon, or copolymers thereof,
Polyamide synthetic fibers such as aramid fibers; polyester synthetic fibers such as polyethylene terephthalate fibers; polyvinylidene fluoride fibers; combinations of monofilaments or multifilaments such as polyether, ether ketone fibers; or polyphenylene sulfide fibers. .

When the monofilament is twisted in order to produce the multifilament, it is needless to say that the visible light curable adhesive composition may be used.

The visible light curable adhesive composition containing the above components is prepared by stirring and mixing the components in a dark place. To produce the string, the synthetic fibrous filaments are aligned and a visible light curable adhesive composition is applied in the dark.
The application can be performed by various methods such as immersion, spraying, and application. However, in order to sufficiently spread the adhesive composition to a deep part, it is preferable to impregnate the adhesive composition by immersion.

After the application of the adhesive composition, the adhesive is polymerized and cured by irradiation with visible light to fix the filament. As described above, the visible light source is 380 to 380.
An incandescent lamp, a dedicated visible light fluorescent lamp having an output characteristic in a short wavelength visible portion, which can emit a light beam having a wavelength of 800 nm, and further, for example, 488 nm, 633 nm,
It is preferable to use a laser beam having a spectral wavelength at 780 nm or the like. Irradiation of visible light is generally 1 to 20 mV / c.
The irradiation may be performed at a radiation intensity of m ² at normal pressure and normal temperature for about 5 seconds to 5 minutes.

The filaments may be impregnated with a visible light curable adhesive composition before being aligned, and then twisted.

A side member may be provided so as to substantially surround the outer periphery of the string thus obtained. The material of the side material is preferably 6-nylon, 6,6-nylon, or a copolymer thereof, or a polyamide such as an aramid;
Or polyester-based synthetic fibers or resins such as polyethylene terephthalate, polybutylene terephthalate, anisotropic polyester, polyvinylidene fluoride,
It is selected from fibers or resins such as polyether, ether ketone, and polyphenylene sulfide in view of creep characteristics, strength, heat resistance and the like.

Further, a resin coating layer may be formed on the outermost periphery. In this case, as the resin, for example, 6-
Examples include polyamide resins such as nylon, 6,6-nylon, 12-nylon, and MXD-nylon, synthetic resins such as polyurethane resins and polyacrylic resins, and copolymers and polymer blends obtained by combining these.
Of these, a uniform resin layer having a high melting point is formed to increase the heat resistance of the string, and further to the string surface, a suitable coefficient of friction, abrasion resistance, and water resistance are imparted.
Synthetic resin, for example, 6-nylon resin, which is easy to coat uniformly with a relatively simple process, is preferable. Further, as a coating method, a melt extrusion coating, a dissolved resin liquid coating, or the like can be applied. In addition, the visible light curable adhesive described above can be used for this coating. The thickness of the resin coating layer is preferably 0.01 to 0.08 mm, more preferably 0.0 to 0.08 mm.
It is good to be 15-0.03 mm.

[0040]

EXAMPLES The strings of the present invention will be further described below with reference to examples, but the present invention should not be construed as being limited based on the description of these examples.

Example 1 Ten 840-denier / 140-filament high-strength nylon (manufactured by Unitika Co., Ltd.) were prepared, and as a visible light-curable adhesive composition, 50% by weight of adipic acid, 1,6-hexane 60 parts by weight of a polyester acrylate as a prepolymer composed of 30% by weight of a diol and 20% by weight of acrylic acid, 38 parts by weight of 1,3-butanediol acrylate as a photopolymerizable monomer, and a p-dialkylaminobenzylidene derivative (2, 6-
Two parts by weight of a visible light polymerization initiation system consisting of 50% by weight of bis (4'-dimethylaminobenzylidene) cyclohexanone) and 50% by weight of diphenyliodonium were mixed and stirred in a dark place to prepare a mixture. Immerse the nylon filament in this visible light curable adhesive composition,
The adhesive composition is applied to the filament, and the diameter is 1.43 m.
After squeezing using a nozzle of m, 1
Twelve 05 denier nylon threads (produced by Unitika Ltd.) were spirally wound and further squeezed using a 1.3 mm diameter nozzle.

Next, a short wavelength of 400 W, a set of two (400 to
500 nm) using a fluorescent lamp (FLR40S CB / M, manufactured by Toshiba Corporation) having an output characteristic in the visible region, 10 cm
2 minutes from the distance of the visible light irradiation at normal temperature and normal pressure,
The adhesive was cured to obtain a wound yarn.

Thereafter, the surface of the wound yarn was subjected to extrusion coating using a thermoplastic polyurethane (manufactured by Dow Chemical Company, Pelesen (trade name)) to form a coating layer having a thickness of 0.025 mm. Thus, the diameter 1.3
A 5 mm string was obtained.

Comparative Example 1 A string having the same thread structure as that used in Example 1 was prepared by using an ultraviolet-curable adhesive (manufactured by Bayer) as an adhesive composition for 200 to 300 n.
Except for irradiating ultraviolet rays with a high-pressure mercury lamp having an output characteristic of m, the same procedure as in Example 1 was carried out.

The above two types of strings were stretched on a racket by a conventional method, and a ball durability test was carried out as follows.

That is, the distance between the test hitting machine and the racket on which each string is set is 2 m, the string surface of the racket is 45 °, and the ball from the test hitting machine hits the string obliquely by 180 ° rotation. ,
The number of hits of the ball until the string was cut was measured.

As a result, the number of hits was 1,062 in the string of the present invention of Example 1, whereas it was 637 in the string of Comparative Example 1. Therefore, it was considered that the string of the present invention had excellent durability, and this was attributed to the fact that the filament was sufficiently fixed to the deep part.

As a result of comparison of the shot feeling by the panelists, no difference was observed between the two, and the results were good.

[0049]

As described above, the present invention has the following effects.

In twisting the filament, the curing reaction of the adhesive composition is carried out using a light source that emits visible light. A cure depth several times that of cure is obtained. For this reason, the curing of the resin sufficiently proceeds even in the deep part of the string, and the resin and the fiber are firmly fixed, so that the hitting durability of the string is significantly improved.

Further, there is no danger of exposure to ultraviolet rays caused by short-wavelength ultraviolet rays, and the burden of equipment costs upon introduction of equipment is greatly reduced, and equipment control is simple.

[Procedure amendment]

[Submission date] October 27, 1999 (1999.10.
27)

[Procedure amendment 1]

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[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a racket string using a synthetic resin filament, wherein the filament is made of an electronic material.
Dialkylaminobenzylidene derivatives as donors
And diphenyliodonium salt as an electron acceptor
It is fixed by a visible light curable adhesive composition including a visible light polymerization initiation system composed of a combination (claim 1). Since this string uses a light source that emits visible light for the adhesive polymerization for fixing the filament, the control of the equipment is easy, the equipment cost and the maintenance cost of the equipment do not increase, and the string base material is not increased. Less likely to damage Further, there is no adverse effect on the human body and the environment at the time of manufacturing. Furthermore, since visible light has little absorption into the synthetic resin and scattering on the synthetic resin surface, the light reaches the deep part, and the adhesive can be sufficiently cured in a short time, and a string with excellent durability can be obtained. can get. Then, if necessary, an ultraviolet absorber may be blended to impart light resistance to the string without difficulty.

[Procedure amendment 3]

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The dialkylaminobenzylidene derivative is composed of 2,6-bis (4'-dimethylaminobenzylidene) cyclohexanone, 2,6-bis (4'-dimethylaminobenzylidene) 4-methylcyclohexanone, and a mixture thereof. It is good to be selected from a group (claim 2 ).

[Procedure amendment 5]

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Further, according to the present invention, there is provided a method for producing a racket string using the synthetic resin filament, wherein the filament comprises a dialkyl alcohol as an electron donor.
Minobenzylidene derivatives and dife as electron acceptors
Providing a visible light curable adhesive composition including a visible light polymerization initiation system comprising a combination with a nyliodonium salt, and then irradiating visible light to cure the visible light curable adhesive composition. (Claim 3 ). By this method, a target string can be manufactured.

Continuation of the front page (72) Inventor Bunichi Ito 3-124 Yakumo-dori, Chuo-ku, Kobe-shi, Hyogo F-term in Toa Strings Co., Ltd. 4L033 AB01 AC15 BA21 CA19 CA45 CA60 CA70

Claims (4)

[Claims] 1. A racket string using a synthetic resin filament, wherein the filament is fixed by a visible light curable adhesive composition. 2. The visible light curable adhesive composition comprises a visible light polymerization initiation system comprising a combination of a dialkylaminobenzylidene derivative as an electron donor and a diphenyliodonium salt as an electron acceptor. The description string. 3. The dialkylaminobenzylidene derivative comprises 2,6-bis (4′-dimethylaminobenzylidene) cyclohexanone, 2,6-bis (4′-dimethylaminobenzylidene) 4-methylcyclohexanone, and a mixture thereof. 3. The string of claim 2, wherein the string is selected from a group. 4. A method for producing a racket string using a synthetic resin filament according to claim 1, wherein a visible light curable adhesive composition is applied to the filament.
A method for producing a racket string, comprising the step of irradiating visible light having a wavelength of 380 to 800 nm to cure the visible light-curable adhesive composition.