JPH06319831A - Golf ball - Google Patents

Abstract

PURPOSE:To improve the spin characteristics of the golf ball and substantially prevent the cause of hangnails by forming the resin components of the cover of specific ratios of an ethylene/methacrylic acid/acrylate polymer and ethylene/(meth)acrylic copolymer having modulus of elasticity in bending and Shore D hardness of specific values. CONSTITUTION:The resin component of the cover is composed of 30 to 100 pts.wt. ionomer resin of inonomer of the ethylene/methacrylic acid/acrylate polymer having 2500 to 14000psi modulus of elasticity in bending and 20 to 59 Shore D hardness and 70 to 0wt.% ionomer resin of the ethylene/(meth) acrylate copolymer having 20000 to 30000psi modulus of elasticity in bending and 56 to 64 Shore D hardness. The core is formed of a rubber compsn. formed by compounding 0.2 to 1.5 pts.wt. pentachlorothiophenol or its metal salt with 100 pts. base material rubber. The deflection weight of the golf ball when 100kg load is applied on the golf ball is specified to 2.3 to 3.3mm.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has excellent controllability, is easy to spin, and is excellent in durability and repulsion property.
The present invention relates to a solid golf ball having sufficient flight performance.

[0002]

BACKGROUND OF THE INVENTION Ionomer resins of ethylene / (meth) acrylic acid copolymers are used in two-piece golf balls and some thread-wound golf balls because of their excellent impact durability and cut resistance. Widely used and accepted as cover material. However, this type of ionomer resin has a harder feel when compared to the balata rubber that has been conventionally used as a cover material, and has a high hardness relative to the balata rubber, which makes it difficult to spin freely on iron shots. It has been said that it is inferior in sex.

Therefore, as an improvement of such a point, ethylene (meth), which is a relatively flexible ionomer resin, is used.
It is possible to use a mixture of an acrylic acid / (meth) acrylic acid ester terpolymer with an ionomer resin of ethylene / (meth) acrylic acid copolymer having a certain physical property within a certain range as a soft / hard ionomer blend golf ball cover. Proposed (US Pat. No. 48848)
No. 14, Japanese Patent Laid-Open No. 1-308577).

This proposal is very effective as a technique for greatly improving hitting hardness and controllability, which are problems of a golf ball using a conventional ionomer resin of ethylene / (meth) acrylic acid copolymer as a cover. It can be said that.

[0005]

However, the soft / hard ionomer blend golf ball cover according to this proposal has the following problems. That is, the softness of the cover and the tendency to spin on the iron shot mean that the frictional force between the club face and the cover is large. Therefore, a hard core material such as a two-piece solid golf ball is used. In the case of a ball using the (core), the cover surface is scraped off by the groove of the iron club at the time of iron shot, and the phenomenon that the ball surface rises up easily occurs.

Further, since the hardness of the ionomer cover is lowered, the resilience of the cover itself is also lowered, and the resilience as a ball is greatly reduced.

Therefore, the feel is good, the spin characteristics are excellent, the controllability is good, the swelling phenomenon does not easily occur, and the resilience is good, and the flight distance peculiar to a solid golf ball such as a two-piece golf ball is good. It is desired to have a solid golf ball that does not damage the golf ball.

[0008]

Therefore, the present inventors have a soft feeling, have good spin characteristics, and do not reduce the repulsion property of the ball. As a result of diligent study on a solid golf ball having improved resistance to fraying, a blend of a so-called intermediate hardness ionomer resin and a soft ionomer resin located at an intermediate hardness between the hard ionomer resin and the soft ionomer resin of the above-mentioned proposal. We have found that blended or soft ionomer resins have much less surface damage on iron shots. It was also found that golf balls using a cover whose surface is fragile have good feel and spin characteristics, but the cover is soft and has low repulsion, making it difficult to use for golf ball applications. Met. However, by using a core containing pentachlorothiophenol or a metal salt thereof, the core becomes highly repulsive, and a sufficient level of repulsion can be obtained as a golf ball. That they can achieve
The present invention has been completed.

That is, the present invention is a golf ball comprising a cover and a solid core, wherein the resin component of the cover has a flexural modulus of 2,500 to 14,000 psi and Shore D.
Ionomer resin 30 to 10 of ethylene / methacrylic acid / acrylic ester terpolymer having a hardness of 20 to 59
0% by weight, flexural modulus 20,000-30,000p
ethylene (meta) with Shore D hardness of 56-64 by si
Acrylic acid copolymer ionomer resin 70 to 0% by weight
And the core is 0.2 to 1.% of pentachlorothiophenol or its metal salt with respect to 100 parts by weight of the base rubber.
Made from a rubber composition compounded with 5 parts by weight, 100 k
A solid golf ball having a deflection amount of 2.3 to 3.3 mm when a g load is applied.

The present invention will be described in more detail below. The golf ball of the present invention has a flexural modulus of 2,50 as a cover.
Ionomer resin of ethylene / methacrylic acid / acrylic acid terpolymer having a Shore D hardness of 20 to 59 at 0 to 14,000 psi, 30 to 100% by weight, preferably 50 to 90% by weight, and a flexural modulus of 20,000 to 3
Ionomer resin 7 of ethylene / (meth) acrylic acid copolymer having Shore D hardness of 56 to 64 at 0000 psi
A blend of 0 to 0% by weight, preferably 50 to 10% by weight, is used.

Here, the former ethylene
As the ionomer resin of the methacrylic acid / acrylic acid ester terpolymer, those shown in Table 1 are available, and as the ionomer resin of the latter ethylene / (meth) acrylic acid copolymer, those shown in Table 2 are available.

[0012]

[Table 1]

[0013]

[Table 2]

If necessary, the cover of the present invention may contain pigments such as dyes, titanium dioxide, zinc oxide and barium sulfate, materials such as UV absorbers and antioxidants, and further dispersion aids such as metal soaps. Etc. can be added, and these materials can be molded by an ordinary method after mixing in a usual mixing, for example, a closed kneading machine (Banbury, kneader) or an extruder.

On the other hand, the core of the present invention is obtained by adding pentachlorothiophenol or a metal salt thereof as an essential component to an ordinary core composition containing a base rubber, an unsaturated carboxylic acid metal salt and a peroxide. To be formed. In this case, as the base rubber, cis-1,4-polybutadiene rubber having a cis structure of 90% or more can be particularly preferably used from the viewpoint of high resilience. In addition, cis-1,4
-Natural rubber, polyisoprene rubber and the like can be appropriately blended with the polybutadiene rubber as desired, but the high cis-1,4-polybutadiene rubber should be contained in the base rubber component in an amount of 80% by weight or more. Is preferred,
If it is less than 80% by weight, the excellent resilience of the high cis-1,4-polybutadiene rubber may be impaired. The metal salt of unsaturated carboxylic acid is blended as a co-crosslinking agent, and zinc salts, magnesium salts and calcium salts of acrylic acid or methacrylic acid are preferable, and zinc acrylate is particularly preferable. The metal salt of unsaturated carboxylic acid is preferably used in an amount of 25 to 40 parts by weight based on 100 parts by weight of the base rubber. As the peroxide, dicumyl peroxide, t-butyl peroxybenzoate, di-t
-Butyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and the like can be used. The amount to be blended is preferably 0.5 to 3 parts by weight, particularly 0.8 to 2 parts by weight, based on 100 parts by weight of the base rubber. Pentachlorothiophenol or its metal salt is preferably added in an amount of 0.2 to 1.5 parts by weight with respect to 100 parts by weight of the base rubber in order to achieve a clear high repulsion property in this compounding system. When compounded, the case where the crosslinking reaction of the core composition of the present invention is inhibited may occur. A zinc salt is preferably used as the metal salt of pentachlorothiophenol.

Further, in this core composition, zinc oxide,
If necessary, a component that can be usually used in the core of an antiaging agent, a two-piece solid golf ball or the like such as barium sulfate can be appropriately blended. This core rubber composition is kneaded with a Banbury or a kneader or the like, and can be cured and molded as a core material of a sphere by high temperature pressure vulcanization according to a conventional method, but in the present invention, as the hardness of the vulcanized product core, The amount of deflection when a 100 kg load is applied to the core is 2.3 to
Use one that is 3.3 mm. If it is less than 2.3 mm, the ball after covering the cover will be hard and the feel will be poor,
If it is larger than 3.3 mm, the repulsion will be low, so
The object of the present invention cannot be achieved.

The golf ball of the present invention can be molded by a conventional molding method,
For example, a half cup may be molded with a cover material in advance, and the solid core may be coated with the half cup, followed by heat compression molding, or a method of coating the cover material around the solid core by direct injection molding.

The cover thickness is preferably 1.4 to 2.5 mm, and the size and weight of the golf ball conform to the rules of the golf ball. Usually, the diameter of the golf ball is 42.67 mm or more, The golf ball weighs 45.93.
g or less.

[0019]

EXAMPLES The present invention will be specifically described below by showing experimental examples, examples and comparative examples, but the present invention is not limited to the following examples.

[Experimental Example 1] A solid core having the composition shown in Table 3 and an ionomer resin having the characteristics shown in Table 4 (HIMIRAN,
Resin composition of Table 5 using SAR2, TiO ₂ ,
A cover material colored with a dispersion aid and adjusted to have a specific gravity of 0.99 was coated by injection molding, surface-treated, and then clear-coated to obtain a two-piece golf ball (cover thickness 2.
0 mm, ball diameter 42.7 mm, ball weight 45.2
The properties of g) were evaluated.

[0021]

[Table 3]

[0022]

[Table 4]

Next, using the obtained ball, three kinds of commercially available pitching wedges were attached to a robot machine, and the ball was hit once at three points at a head speed of 37 m / s,
Three hitting parts were observed, and three grades were evaluated according to the following evaluation criteria. The results are shown in Table 5. ◯: A slight mark on the club face is left, but it is hardly noticeable. △: A clear mark on the club face is left, but there is no feathering on the cover surface. ×: The surface is flaky or noticeable feathering.

[0024]

[Table 5]

From the above results, the cover of the present invention had good resistance to fraying by the iron club face.

[Experimental Example 2] A core (diameter 38.7 mm) having the composition shown in Table 6 was prepared, and the amount of deflection when a load of 100 kg was applied and the initial velocity of the core were examined. In this case, the initial velocity of the core was measured by using an initial velocity meter of the same type as the golf ball official organization R & A (USGA). The results are shown in Table 6.

[0027]

[Table 6]

From the results shown in Table 6, it was confirmed that the core of the present invention had a high initial velocity and was excellent in resilience.

[Examples and Comparative Examples] Two-piece golf balls (cover thickness 2.0 mm, golf ball diameter 42.7 mm, ball weight 45.2 g) were manufactured by combining the cover and core shown in Table 7, and the balls were manufactured. The initial velocity was examined in the same manner as above, and the backspin number, the stop on the green, and the flight distance of the driver were evaluated. The results are shown in Table 7.

[0030]

[Table 7] * 1: An iron club (pitching wedge) was attached to a swing robot machine, hit with a head speed of 37 m / s, and the ball behavior immediately after impact was photographed and analyzed. * 2: Evaluation was made by the difference in distance between the drop position and the stop position when the ball was hit so as to drop directly on the green under the same conditions as in * 1. * 3: A driver W # 1 was attached to the swing robot machine, and the flight distance when hit with a head speed of 45 m / s was evaluated.

From the results shown in Table 7, it was confirmed that the golf ball of the present invention has excellent controllability and flight performance.

[0032]

INDUSTRIAL APPLICABILITY The golf ball of the present invention has excellent spin characteristics, good rust resistance, and good repulsion.

Claims (1)

[Claims] 1. A golf ball comprising a cover and a solid core, wherein the resin component of the cover has a bending elastic modulus of 2,5.
Shore D hardness of 20 to 59 at 00 to 14,000 psi
Ethylene-methacrylic acid-acrylic acid ester terpolymer ionomer resin of 30 to 100% by weight, and an ethylene- (meth) acrylic acid copolymer having a flexural modulus of 20,000 to 30,000 psi and a Shore D hardness of 56 to 64 70% to 0% by weight of an ionomer resin, and a core formed from a rubber composition in which 0.2 to 1.5 parts by weight of pentachlorothiophenol or a metal salt thereof is mixed with 100 parts by weight of a base rubber. , A solid golf ball having a deflection amount of 2.3 to 3.3 mm when a 100 kg load is applied.