JPH0683730B2 - Thread wound golf ball - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thread-wound golf ball in which a cover layer is formed on a thread rubber layer formed around a core ball, and more specifically, a thread forming the thread rubber layer. A thread-wound golf ball having improved flight characteristics by using, as the rubber, a hysteresis loss at the time of high drawing is small, excellent tensile strength and elongation at high temperature, and having good processability at the time of manufacturing the thread rubber. .

2. Description of the Related Art Conventionally, a thread rubber layer of a thread-wound golf ball is formed of a thread rubber whose main components are natural rubber (NR) and synthetic isoprene rubber (IR). This is because the thread rubber containing only natural rubber as a main component has a large hysteresis loss at the time of high stretching. Therefore, when this is used, it is difficult to obtain a thread rubber layer having high elasticity. A highly elastic thread rubber layer is obtained by using a thread rubber blended with a synthetic isoprene rubber having a small value. In this case, as the compounding amount of the synthetic isoprene rubber with respect to the natural rubber is increased, the hysteresis loss at the time of high stretching of the thread rubber becomes smaller. Therefore, the elasticity is higher and the flight characteristics are excellent as the thread rubber having a higher synthetic isoprene rubber content is used. It is considered possible to obtain a golf ball.

Problems to be Solved by the Invention However, conventionally, there has been a limit to increase the compounding amount of synthetic isoprene rubber with respect to natural rubber in order to improve flight characteristics. That is, when the compounding amount of the synthetic isoprene rubber with respect to the natural rubber is increased, the properties of the thread rubber, particularly the tensile strength and the elongation at high temperature, are remarkably reduced, and therefore the thread rubber having a large content of the synthetic isoprene rubber is involved. Cannot be used as a material for the rubber thread layer which undergoes a high heat history when the cover layer is covered. Further, there is a problem that it is difficult to obtain a uniform rubber sheet with a rubber material having a high synthetic isoprene rubber content, and further, the processability at the time of producing a rubber thread is poor.

Therefore, even if the ratio of synthetic isoprene rubber to natural rubber is higher than before, the hysteresis loss is small, and
A rubber material which is excellent in tensile strength and elongation at high temperature and has good workability during production of a thread rubber and which is suitable for obtaining a highly elastic thread rubber layer has been desired. As a result of various studies on obtaining materials, rubber materials containing natural rubber and synthetic isoprene as main components, and natural rubber and isoprene in a weight ratio of 50:50 to 10:90 were used. , A synthetic isoprene rubber having a cis-1,4 bond of 80% or more is used as a synthetic isoprene rubber, and a vulcanizable rubber is incorporated into the molecule. The reinforced rubber composition in which the short fibers of the thermoplastic polymer having the above is grafted through the initial condensation product of the phenol-formaldehyde resin, and the blending amount of the short fibers of the thermoplastic polymer is 1 with respect to 100 parts by weight of all rubber components. By blending so that the content is up to 15 parts by weight, even if the synthetic isoprene rubber content is increased, a rubber material having high tensile strength and elongation at high temperature and good workability can be obtained. Therefore, the synthetic isoprene rubber content is high. As a result, the inventors have found that a thread rubber layer can be satisfactorily formed of a rubber material having a small hysteresis loss, and that a thread wound golf ball excellent in flight identification can be obtained, and the present invention has been completed.

That is, the wound golf ball has a larger flight distance as the hysteresis loss of the thread rubber is smaller. Therefore, it is preferable for the thread rubber to contain a large amount of synthetic isoprene rubber, which has a smaller hysteresis loss at the time of high stretching, as compared with natural rubber. However, by mixing the synthetic isoprene rubber, the workability is deteriorated, and the physical properties of the rubber, particularly the tensile strength and elongation at high temperature, are significantly deteriorated. In the present invention, the rubber component is blended with the thermoplastic polymer short fibers to reinforce the rubber, thereby significantly improving the processability and physical properties of the rubber, particularly the tensile strength at high temperature and elongation, and increasing the synthetic isoprene rubber content. It is also possible to improve the flight characteristics of the ball by using the synthetic isoprene rubber having 80% or more of cis-1,4 bonds as the synthetic isoprene rubber.

Hereinafter, the present invention will be described in more detail.

The golf ball according to the present invention is a thread-wound golf ball obtained by coating a rubber thread layer formed around a core ball layer with a cover layer. -Synthetic isoprene rubber having 80% or more of 1,4 bonds and vulcanizable rubber in the molecule And a reinforced rubber composition in which short fibers of a thermoplastic polymer having the above are grafted through an initial condensation product of a phenol formaldehyde resin.

In this case, by using a synthetic isoprene rubber having 80% or more of cis-1,4 bonds, the flight characteristics of the ball can be improved.

Examples of the reinforced rubber composition include a vulcanizable rubber and -CONH- in a polymer molecule having a molecular weight of less than 200,000.
Of a thermoplastic polymer having a group, an initial condensate of 0.2 to 5 parts by weight of a phenol formaldehyde resin per 100 parts by weight of the total amount of the rubber and the thermoplastic polymer, and a compound capable of generating formaldehyde when heated The kneaded product is kneaded at a temperature not lower than the melting point of the polymer and not higher than 270 ° C., and the resulting kneaded product has a ratio of the rubber and the thermoplastic polymer of 1 to 100 parts by weight of the thermoplastic polymer per 100 parts by weight of the rubber. When the ratio of the rubber and the thermoplastic polymer in the kneaded product is more than 100 parts by weight of the thermoplastic polymer per 100 parts by weight of the rubber, the additional vulcanizable rubber is heated per 100 parts by weight of the entire rubber. 1 to 1 plastic polymer
It is added to the kneaded product in an amount of 00 parts by weight, further kneaded at a temperature not lower than the melting point of the thermoplastic polymer and not higher than 270 ° C., and then extruded at a temperature not lower than the melting point of the thermoplastic polymer and not higher than 270 ° C. What was manufactured by extending | stretching at a temperature lower than the melting point of a thermoplastic polymer can be used conveniently.

In this case, as the vulcanizable rubber, it is possible to use all rubbers that give a rubber elastic body by vulcanization, for example, natural rubber, cis-1,4-polybutadiene, polyisoprene, polychloroprene, Examples thereof include styrene-butadiene copolymer rubber, isoprene-ibutylene copolymer, ethylene-propylene-non-conjugated diene terpolymer, and a mixture thereof. Among these rubbers, a mixture of a vulcanizable rubber, a thermoplastic polymer having a -CONH- group in the molecule and an initial condensate of a phenol formaldehyde resin, and a compound capable of generating formaldehyde upon heating is kneaded, and this kneading is performed. A natural rubber that hardly gels when extruding a material is preferable.

Further, the fine short fibers of the thermoplastic polymer have a melting point of
190-235 ° C, preferably 190-225 ° C, particularly preferably 20
Nylon 6, Nylon 610, Nylon 1 which is 0-220 ℃
2, Nylon such as nylon 611 and nylon 612, polyhebutamethylene urea, polyundecamethylene urea and other polyureas, and polyurethane and other polymer molecules -CONH-
It is preferably formed from a thermoplastic polymer having a group, particularly nylon, has an average diameter of 0.05 to 0.8 µ, has a circular cross section, and has a shortest fiber length of preferably 1 µ or more and has a molecule in the fiber axial direction. It is preferably embedded in vulcanizable rubber in the form of aligned fine short fibers.

The phenol-formaldehyde resin has the following general formula (Wherein R is an alkyl group or a combination of a hydrogen atom and an alkyl group, X is a hydroxyl group or a halogen atom such as chlorine or bromine, m is 1 or 2, and n is
Is an integer of 2 to 15. ) Resol type alkylphenol-formaldehyde resin, such as a resol type initial condensate obtained by reacting an alkylphenol such as cresol with formaldehyde or acetaldehyde in the presence of an alkali catalyst, and a modified product thereof. In this case, as the resol type alkylphenol formaldehyde resin, one having two or more methylol groups in the molecule can be particularly preferably used.

Further, as the phenol-formaldehyde-based resin, for example, phenols such as phenol and bisphenols and formaldehyde (paraformaldehyde may be used) by using an acid such as sulfuric acid, hydrochloric acid, phosphoric acid and oxalic acid as a catalyst.
Examples thereof include novolak-type phenol-formaldehyde resins such as soluble and fusible resins obtained by subjecting and to a condensation reaction and modified products thereof. In this case, as the novolac type phenol formaldehyde resin, for example, novolac type phenol formaldehyde precondensate, novolac type lactam-bisphenol F-formaldehyde precondensate, novolac type styrenated phenol-phenol-formaldehyde precondensate are preferably used. it can.

The reinforced rubber composition is 1-100 parts by weight of fine short fibers of a thermoplastic polymer having a -CONH- group in the polymer molecule in 100 parts by weight of the vulcanizable rubber, preferably 1-70 parts.
It is preferred that parts by weight, particularly preferably 30 to 70 parts by weight, are embedded.

Further, in the above-mentioned reinforced rubber composition, a thermoplastic polymer is embedded in the vulcanizable rubber through an initial condensation product of a phenol-formaldehyde resin at an interface of the fine fibers of the thermoplastic polymer embedded in the vulcanizable rubber. The graft ratio, which is represented by the weight ratio of the vulcanizable rubber graft-bonded (vulcanizable rubber / fine thermoplastic polymer fine fibers), is 3 to 25% by weight, particularly 5 to 20% by weight. As described above, it is preferable that the thermoplastic polymer forming the fiber and the vulcanizable rubber are graft-bonded via the precondensation product of the phenol-formaldehyde resin.

In the rubber thread used in the present invention, the compounding ratio (weight ratio) of the natural rubber and the synthetic isoprene rubber is 50:50 to 1 in terms of rubber content.
It is 0:90. In this case, the rubber thread of the present invention has a large tensile strength and elongation at high temperature, and has good processability during manufacturing of the rubber thread, even if the synthetic isoprene rubber content is increased to reduce the hysteresis loss during high stretching. is there.

Further, the reinforced rubber composition is blended so that the staple fibers of the thermoplastic polymer are contained in an amount of 1 to 15 parts by weight, preferably 2 to 5 parts by weight, based on 100 parts by weight of the total rubber component. In this case, when the short fibers of the thermoplastic polymer are more than 15 parts by weight, the increase of hysteresis loss due to the addition of this becomes remarkable,
The effect of compounding synthetic isoprene rubber may be offset, and the effect due to its addition may be lost even in consideration of high temperature characteristics.

The rubber thread used in the present invention includes a vulcanizing agent and other conventional additives such as antioxidants, reinforcing agents, plasticizers,
It is prepared by an ordinary method by appropriately adding a filler, other compounding chemicals and the like. In this case, other rubber components may be blended, for example, polybutadiene rubber, etc.
It does not matter if the amount is 10% by weight or less.

The thread-wound golf ball of the present invention can be produced by winding the thread rubber on a core ball and coating the thread rubber layer with an outer cover. In this case, the core ball is formed by using a commonly used material. In addition, the outer skin can be formed by using a usual material such as balata or an ionomer resin.

The weight, thickness, etc. of the core ball, the rubber thread layer, and the outer cover can be set within the usual ranges.

EFFECTS OF THE INVENTION As described above, the golf ball according to the present invention is a thread-wound golf ball in which a rubber thread layer formed around a core ball layer is covered with a cover layer. Natural rubber, synthetic isoprene rubber having 80% or more cis-1,4 bonds, and vulcanizable rubber in the molecule
Hysteresis loss of the thread rubber is small by using the specified amount of the reinforced rubber composition in which the CONH-group-containing thermoplastic polymer short fibers are grafted through the initial condensation product of the phenol-formaldehyde resin. ,
In addition to having excellent flight characteristics, the rubber thread has high tensile strength and elongation at high temperatures, and has good workability during manufacturing of the rubber thread, which is advantageous in manufacturing.

Next, production examples of the reinforced rubber composition used in the present invention will be shown.

[Production example] 1400 g of natural rubber with 100 ° C Mooney viscosity of 25 in an OOC Banbury mixer (Kobe Steel) set at 150 ° C, 100 rpm
And N- (3-methacryloyloxy-2-hydroxypropyl) -N-phenyl-p-phenylenediamine (trade name: Nocrac G-1, Ouchi Shinko Chemical Industry Co., Ltd.)
14g, and after masticating for 1 minute, 6-nylon (trade name: 1030B, Ube Industries, Ltd., melting point 221 ° C, molecular weight
30000) 700 g was added and the mixture was kneaded for 7 minutes. During this time, the temperature in the mixer rose to 232 ° C, and 6-nylon melted.

Next, add 30 g of novolac type phenol formaldehyde initial condensate (trade name: 550PL Showa Kasei Co., Ltd.),
After masticating for 7 minutes, 3 g of hexamethylenetetramine was added, and the mixture was kneaded for 2.5 minutes (the temperature of the mixer batter during this time was 230 ° C.) for a graft reaction and then dumping.
Using the 30 mm (diameter) extruder (made by Ikegai) having a circular diamond having an inner diameter of 2 mm and a ratio of length to inner diameter (L / D) of 2 to the resulting masticated product, a string is set at a die temperature of 235 ° C. The resulting extrudate was cooled and solidified with 0 ° C. cooling water, and then wound on a bobbin at a draft ratio of 9 and a speed of 35 m / min through a guide roll. After vacuum-drying this roll at room temperature for 24 hours and removing water that has adhered to it, about 500 rolls are bundled into a sheet (thickness 2 mm, width 150 mm), and the roll interval is 0.2 mm. , About 1 with a pair of rolling rolls at a temperature of 60 ℃
Rolling was performed 0 times to obtain a reinforced rubber composition.

This manufacturing method is based on the method described in JP-A-59-43041.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

[Examples and Comparative Examples] No. 1 to 5 thread rubbers having the compositions shown in Table 1 were produced by a conventional method. The synthetic isoprene rubber is Cari manufactured by Shell Chemical Co.
flex 309 (containing 91.5% of cis-1,4 bond) was used.

Then, the tensile strength and elongation of these thread rubbers at room temperature and 70 ° C. were measured and comparatively examined. The results are shown in Table 1. The retention rate in Table 1 is the ratio (%) of the tensile strength or elongation at 70 ° C to the tensile strength or elongation at room temperature.

From the results in Table 1, Nos. 2 to 4 used in the present invention (Examples)
It was confirmed that the rubber thread of No. 2 was extremely excellent in tensile strength and elongation at high temperature. On the other hand, the rubber thread No. 1 (comparative example) containing no short nylon fiber was significantly inferior in tensile strength and elongation at high temperature. Also, No.5
The rubber thread of Comparative Example was inferior in elongation at room temperature.

Next, after heating each rubber composition (No.1 to No.5), 0.5mm
It was calendered into a thick sheet. As a result of evaluating the calender workability from the presence or absence of perforation on the skin of each of the obtained sheets, there was no problem with the rubber compositions of No. 2 to 5, but holes were formed in the sheet of the No. 1 rubber composition. It was confirmed that the workability was poor.

Further, when a thread rubber was prepared from each of the obtained sheets and the thread winding workability was examined, the thread rubbers of the rubber compositions No. 1 to 4 had good thread winding workability, but the rubber composition No. 5 In the case of the rubber thread of the composition, the elongation was small, and as a result, a normally wound ball could not be obtained.

Claims (1)

[Claims] 1. A thread-wound golf ball comprising a rubber thread layer formed around a core ball and a cover layer covering the rubber layer. The rubber thread forming the rubber thread layer is made of natural rubber and cis-1,4 bond. Synthetic isoprene rubber with more than wt% and vulcanizable rubber in the molecule Containing a reinforced rubber composition in which short fibers of a thermoplastic polymer having a are grafted through an initial condensation product of a phenol-formaldehyde resin, and the compounding ratio of natural rubber and synthetic isoprene rubber is 50:50 by weight. 50 to 10:90, characterized in that the reinforced rubber composition is used such that the blending amount of the short fibers of the thermoplastic polymer is 1 to 15 parts by weight with respect to 100 parts by weight of the total rubber component. A thread-wound golf ball.