JPH10179801A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball of multi-layer structure including thread rubber layers, which gives a fine feeling of striking a ball and also good controllability and whose flying performance and anti-cut property lie at a satisfactory level. SOLUTION: A golf ball has a thread winding core 1 and a cover 2 enclosing the core 1, wherein the resin as base material of the cover 2 is chiefly composed of a heated mixture consisting of ionomer resin, acid-denatured thermoplastic elastomer or a thermoplastic elastomer to whose termination -OH radical is added, and styrene-butadiene-styrene block copolymer having a polybutadiene block containing epoxy radical or a styrene-isoprene-styrene block copolymer having a polyisoprene block containing epoxy radical, and the bending rigidity of the compond for the cover 2 should range 50 to 300MPa while Shore D hardness range 40 to 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a golf ball. More specifically, the present invention relates to a golf ball having a multilayer structure having a rubber thread layer, which has good hit feeling (feeling at hitting) and controllability, and satisfactory flight performance and cut resistance. Golf ball.

[0002]

2. Description of the Related Art In recent years, ionomer resins have been widely used as base resins for cover of golf balls (for example, Japanese Patent Publication No. 49-27093). This is because the ionomer resin has excellent durability, cut resistance, and resilience, and is easy to process.

However, since this ionomer resin has considerably high hardness and rigidity, it is inferior to balata (trans polyisoprene) in terms of shot feeling and controllability (easiness of spinning).

[0004] Therefore, attempts have been made to improve the feel at impact and controllability by softening the ionomer resin by various means.

For example, JP-A-1-308577 and JP-A-5-3931 disclose a ternary copolymer of an ionomer resin with an α-olefin and an unsaturated carboxylic acid such as acrylic acid or methacrylic acid and an acrylate ester. It has been proposed to soften a high-rigidity ionomer resin by blending (mixing) a soft ionomer resin neutralized with sodium ions or zinc ions to improve the shot feeling and controllability.

However, even if the soft ionomer resin is blended as described above, it is not possible to obtain a golf ball having a feeling close to a balata cover in terms of shot feeling, and the resilience performance and flight performance are reduced with the blend of the soft ionomer resin. It has not been successful enough.

JP-A-5-220240 proposes to improve the shot feeling and controllability by blending an ionomer resin with a polymer containing a glycidyl group as a constituent. According to this method, although the shot feeling and the control are somewhat improved, they are still insufficient, and a golf ball having sufficient resilience performance and flight performance has not been obtained.

[0008]

As described above, a golf ball using an ionomer resin as a base resin for a cover has poor hitting feel and controllability, and proposals for improving it include rebound performance and flight performance. Such as lowering the performance,
It has not been successful enough.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a golf ball having a multilayer structure having a rubber thread layer, which has good hit feeling and controllability, and has satisfactory flight performance and cut resistance. And

[0010]

SUMMARY OF THE INVENTION In view of the above circumstances, the inventor of the present invention has proposed a cover for achieving both excellent hit feeling and controllability close to a balata cover and excellent flight performance and cut resistance based on an ionomer resin. As a result of intensive studies on the base resin, an ionomer resin, a soft acid-modified thermoplastic elastomer or a thermoplastic elastomer having an -OH group added to a terminal, and a styrene-butadiene having a polybutadiene block containing a soft epoxy group are provided. -Styrene block copolymer or styrene having a polyisoprene block containing a soft epoxy group-
When a heated mixture with an isoprene-styrene block copolymer is used as the main component of the base resin of the cover, a golf ball having good hit feeling and controllability and satisfactory flight performance and cut resistance is used. Was found, and the present invention was completed.

That is, the present invention relates to a golf ball having a wound core and a cover for covering the wound core, wherein the base resin of the cover is an ionomer resin, an acid-modified thermoplastic elastomer or an -OH group added to a terminal. Thermoplastic elastomer and styrene-butadiene having an epoxy group-containing polybutadiene block
A styrene-block copolymer or a styrene-isoprene-styrene block copolymer having an epoxy group-containing polyisoprene block is mainly composed of a heated mixture, and the cover composition constituting the cover has a flexural rigidity of 50. A golf ball characterized by having a Shore D hardness of 40 to 60 MPa and a Shore D hardness of 40 to 60 MPa. The styrene-butadiene-styrene block copolymer portion in the styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group is one that is abbreviated as a block copolymer having an SBS structure, Styrene-isoprene having polyisoprene block containing epoxy group
The styrene-isoprene-styrene block copolymer portion in the styrene block copolymer is abbreviated as a block copolymer having an SIS structure.

Hereinafter, the present invention will be described in detail. In the description, an ionomer resin is used as a component (A),
A styrene-butadiene-styrene block copolymer having an epoxy group-containing polybutadiene block or an epoxy group-containing polyisoprene, comprising an acid-modified thermoplastic elastomer or a thermoplastic elastomer having a terminal -OH group added thereto as a component (B). A styrene-isoprene-styrene block copolymer having a block (C)
It will be described as a component.

In the present invention, the ionomer resin of the component (A) is added as a soft component with the acid-modified thermoplastic elastomer of the component (B) or the thermoplastic elastomer having a terminal -OH group added thereto. The ionomer resin is softened, and the shot feeling and controllability are improved. In addition, the ionomer resin (A) and the thermoplastic elastomer (B)
(C) A styrene-butadiene-styrene block copolymer having a soft epoxy group-containing polybutadiene block or a styrene-isoprene-styrene block copolymer having a soft epoxy group-containing polyisoprene block is added. Since the mixture is heated and mixed, the epoxy group of the block copolymer containing the epoxy group of the component (C) becomes free carboxyl groups in the ionomer resin of the component (A) and the acid modification of the component (B) during the heating and mixing. Acid or terminal -O in thermoplastic elastomer
Reacts with -OH groups in the thermoplastic elastomer to which the H group is added, and achieves uniform fine dispersion of the acid-modified thermoplastic elastomer of the soft component or the thermoplastic elastomer with the -OH group added to the terminal to the ionomer resin, and As the improvement of the resilience performance of the acid-modified thermoplastic elastomer or the thermoplastic elastomer having a -OH group added to the terminal is achieved,
Excellent flight performance (rebound performance) of ionomer resin
Thus, a golf ball having good shot feeling and controllability and excellent flight performance, cut resistance, durability and the like can be obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, among the components constituting the base resin of the cover, the ionomer resin used as the component (A) includes, for example, α-olefin and α, β- One obtained by neutralizing at least a part of the carboxyl group in the copolymer with an unsaturated carboxylic acid with a metal ion, or an α-olefin and a carbon number of 3 to
Α, β-unsaturated carboxylic acid of 8 and α, β of 2 to 22 carbon atoms
Those obtained by neutralizing at least a part of carboxyl groups in a terpolymer with a β-unsaturated carboxylic acid ester with a metal ion are exemplified. When the base polymer of the ionomer resin is a copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, the α-olefin is 80 to 90% by weight.
Preferably, the α, β-unsaturated carboxylic acid is 10 to 20% by weight, and the base polymer is an α-olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and a C 2 to 2
In the case of a terpolymer with an α, β-unsaturated carboxylic acid ester of No. 22, the α-olefin is 70 to 85% by weight,
When the α, β-unsaturated carboxylic acid is 5 to 20% by weight,
-It is preferred that the unsaturated carboxylic acid ester is 10 to 25% by weight. Also, these ionomer resins are
The melt index (MI) is 0.1 to 20, especially 0.1.
It is preferably 5 to 15.

As the above-mentioned α-olefin, for example, ethylene, propylene, 1-butene, 1-pentene and the like are used.
As the α, β-unsaturated carboxylic acid of No. 8, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid and the like are used, and acrylic acid and methacrylic acid are particularly preferable. Examples of the unsaturated carboxylic acid ester having 2 to 22 carbon atoms include, for example, methyl, ethyl, propyl, n-butyl and isobutyl esters such as acrylic acid, methacrylic acid, fumaric acid and maleic acid. Acid esters and methacrylic esters are preferred. A copolymer of the above-mentioned α-olefin and α, β-unsaturated carboxylic acid or a copolymer of α-olefin, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms Examples of the metal ion that neutralizes at least a part of the carboxyl group in the original copolymer include, for example, sodium ion, lithium ion, zinc ion,
Magnesium ions, potassium ions and the like can be mentioned. When the ionomer resin is obtained by neutralizing at least a part of the carboxyl groups in the copolymer of ethylene and acrylic acid or methacrylic acid with metal ions, the melt index is 3 to 7, and the flexural rigidity is 3 to 7. It is preferable to use a so-called high-rigidity high-flow type having a modulus of 200 to 400 MPa.

When specific examples of the above-mentioned ionomer resins are exemplified by trade names, for example, ionomer resins commercially available from Mitsui DuPont Polychemicals Co., Ltd. include Himilan 1605 (Na) and Himilan 1707
(Na), Himilan AM7318 (Na), Himilan 1706 (Zn), Himilan AM7315 (Z
n), Himilan AM7317 (Zn), Himilan A
M7311 (Mg), Himilan MK7320 (K)
And Himilan 1856 (Na), Himilan 1855 (Zn), and Himilan AM7316 (Zn) as terpolymer ionomer resins. Examples of ionomer resins commercially available from DuPont, USA include Surlyn 8920 (Na) and Surlyn 8940 (N
a), Surlyn AD8512 (Na), Surlyn 991
0 (Zn), Surlyn AD8511 (Zn), Surlyn 7930 (Li), Surlyn 7940 (Li), and Surlyn AD82 as a terpolymer ionomer resin
65 (Na), Surlyn AD8269 (Na) and the like. Ionomer resins commercially available from Exxon Chemical Company include Iotek 7010 (Zn), Iotek 8000 (Na) and the like. In addition,
Na, Zn, K, Li, Mg and the like described in parentheses after the trade name of the ionomer resin indicate the metal species of the neutralizing metal ion. In the present invention,
As the ionomer resin, two or more of the above-described examples may be used in combination, and an ionomer resin neutralized with a monovalent metal ion and an ionomer resin neutralized with a divalent metal ion may be used. You may mix and use 2 or more types.

Examples of the acid-modified thermoplastic elastomer in the acid-modified thermoplastic elastomer (B) or the thermoplastic elastomer having a terminal -OH group added thereto include a maleic anhydride-modified thermoplastic elastomer, ethylene and an unsaturated carboxylic acid. Ternary copolymers of esters and unsaturated carboxylic acids, and the like. Examples of the thermoplastic elastomer having a terminal —OH group added include, for example, SE
A block copolymer having a BS structure and a block copolymer having a SEPS structure are exemplified. This SEBS structure is a structure obtained by hydrogenating a double bond of a butadiene portion in a styrene-butadiene-styrene block copolymer,
The SEPS structure is a structure in which hydrogen is added to a double bond of an isoprene portion in a styrene-isoprene-styrene block copolymer. The structure obtained by hydrogenating the double bond of the butadiene portion in the styrene-butadiene-styrene block copolymer having an -OH group added to the terminal or-
In the styrene-isoprene-styrene block copolymer to which the OH group is added, the block copolymer having a structure in which the double bond of the isoprene moiety is hydrogenated has a styrene content of 10 to 70% by weight, particularly 15 to 50% by weight. %. When the styrene content is less than 10% by weight, the cover may be too soft and the cut resistance may be reduced. When the styrene content is more than 70% by weight, the ionomer resin can be sufficiently softened. And the shot feeling and controllability may be deteriorated. In the following, styrene-butadiene-
The structure obtained by hydrogenating the double bond of the butadiene portion of the styrene block copolymer is abbreviated as SEBS structure, and the structure obtained by hydrogenating the double bond of the isoprene portion in the styrene-isoprene-styrene block copolymer is referred to as SEPS structure. Abbreviated.

Commercially available maleic anhydride-modified thermoplastic elastomers include, for example, a maleic anhydride of a hydrogenated styrene-butadiene-styrene block copolymer under the trade name of "TUFTEC M Series" from Asahi Kasei Corporation. Acid adducts are marketed in various grades, and ethylene-ethyl acrylate-maleic anhydride terpolymer is marketed in various grades from Sumitomo Chemical Co., Ltd. under the trade name "Bondane". From DuPont-Mitsui Polychemicals, Inc., under the trade name of “AR series”, graft-modified ethylene-ethyl acrylate copolymers with maleic anhydride are marketed in various grades, and Kuraray Co., Ltd. XE-1403 ", a hard segment of maleic anhydride-modified thermoplastic elastomer. In sexual polyolefins, soft segment block polymer of amorphous polyolefins are commercially available.

Examples of the terpolymer of ethylene, unsaturated carboxylic acid ester and unsaturated carboxylic acid include products such as "Nucrel AN4212C" and "Nucrel N0805J" from DuPont Mitsui Polychemicals, Inc. Ethylene-isobutyl acrylate-methacrylic acid terpolymer is commercially available.

Commercially available block copolymers having the SEBS structure or the SEPS structure with an -OH group added to the terminal are, for example, "HG-25" available from Kuraray Co., Ltd.
2 "trade name, hydrogenated styrene-isoprene-
A styrene block copolymer having a terminal added with an -OH group is commercially available.

The acid-modified thermoplastic elastomer (B) or the thermoplastic elastomer having a terminal -OH group added thereto is used for the purpose of softening the ionomer resin (A) and constitutes a cover. In order to make the cover composition have a flexural rigidity of 50 to 300 MPa and a Shore D hardness of 40 to 60, a JIS-A hardness of 30 to 9 is required.
It is preferable that the hardness is 0 or the Shore D hardness is 5 to 40. The above acid-modified thermoplastic elastomer or -O at the terminal
When the JIS-A hardness of the thermoplastic elastomer to which the H group is added is 30 or the Shore D hardness is lower than 5, the cover may be too soft and the cut resistance may be reduced. Alternatively, when the Shore D hardness is higher than 40, the softening of the ionomer resin cannot be sufficiently achieved, and the shot feeling and controllability may not be sufficiently improved. In particular, the JIS-A hardness of 4
It is preferable that the hardness is 0 to 88 or the Shore D hardness is 10 to 40. The JIS-A hardness is a hardness measured with a JIS-A type hardness meter according to JIS K6301, and the Shore D hardness is ASTM D with a Shore D type hardness meter.
It is a hardness measured according to -2240.

In the present invention, a styrene-containing polybutadiene block containing an epoxy group as the component (C) is used.
Butadiene-styrene block copolymer is a block copolymer having polystyrene at both ends, the intermediate layer of which is polybutadiene containing an epoxy group, and part or all of the double bonds of the polybutadiene portion are hydrogenated. May be done. Further, a styrene-isoprene-styrene block copolymer having a polyisoprene block containing an epoxy group is a block copolymer having polystyrene at both ends, and an intermediate layer thereof is a polyisoprene containing an epoxy group, Some or all of the double bonds of the polyisoprene portion may be hydrogenated.

Here, the basic structure of the styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group as the component (C) is as shown in the following formula (I).

[0024]

Embedded image

Further, the styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group as the component (C) has a part of the double bond of the polybutadiene portion in the formula (I) showing the above basic structure. Alternatively, all of them may be hydrogenated. And
The styrene-isoprene-styrene block copolymer having a polyisoprene block containing an epoxy group as the component (C) has a basic structure in which the polybutadiene block in the above formula (I) is replaced by a polyisoprene block, The styrene-isoprene-styrene block copolymer having an epoxy group-containing polyisoprene block as the component (C) is obtained by hydrogenating a part or all of the double bonds of the polyisoprene portion in the basic structural formula. It may be something. Hereinafter, regarding the component (C), the epoxidized SBS structure or the SI
Abbreviated as block copolymer having S structure.

The epoxidized SBS structure or SIS structure block copolymer (C) has a styrene content of 1
It is preferably from 0 to 50% by weight, particularly preferably from 15 to 45% by weight. When the styrene content is less than 10% by weight, the cover may be too soft and the cut resistance may decrease. When the styrene content is more than 50% by weight, the softness of the ionomer resin of the component (A) may be reduced. Satisfactorily, the shot feeling and controllability may be deteriorated.

The epoxidized SBS of the component (C)
The epoxy group content of the block copolymer having the structure or the SIS structure is preferably 0.05 to 10% by weight, particularly preferably 0.2 to 5% by weight. When the content of the epoxy group is less than 0.05% by weight, the reaction amount of the epoxy group is reduced, and the acid-modified thermoplastic elastomer of the component (B) or the -OH group at the terminal is added to the ionomer resin of the component (A). There is a possibility that the dispersibility of the thermoplastic elastomer to which is added or the epoxidized SBS structure or SIS structure block copolymer of the component (C) is reduced and the durability is deteriorated. Also,
When the content of the epoxy group is more than 10% by weight, the reaction amount of the epoxy group becomes too large, the fluidity is deteriorated, and the molding of the ball may be difficult.

The epoxidized SBS-structure or SIS-structure block copolymer of the component (C) is as soft as the acid-modified thermoplastic elastomer of the component (B) or the thermoplastic elastomer having a terminal -OH group added thereto. The JIS-A hardness is preferably from 30 to 90, since it also has the purpose of chemical conversion. (C) The epoxidized SBS structure or SIS structure block copolymer of the component has a JIS-A hardness of 3
If it is lower than 0, the cover becomes too soft and the cut resistance may be reduced. If the JIS-A hardness is higher than 90, the softening of the ionomer resin cannot be sufficiently achieved, and the shot feeling and Controllability may not be sufficiently improved, and particularly, JIS-A hardness of 40 to
It is preferably 88.

Commercial products of the epoxidized SBS structure or SIS structure block copolymer of the component (C) include:
For example, “ESBS A” from Daicel Chemical Industries, Ltd.
1005 ”(this“ ESBS A1005 ”
S AT014 ”).)
“ESBS A1010” (this “ESBS A101
0 ”is a name changed from“ ESBS AT015 ”),“ ESBSA1020 ”(this“ ESBS AT015 ”).
A1020 "is a name changed from" ESBS AT000 "), or a styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group, which is commercially available under a trade name such as" ESBS AT000 ", or" ESBS AT018 ", "ESBS AT01
A styrene-butadiene-styrene block copolymer obtained by partially hydrogenating an epoxy group-containing polybutadiene block, which is commercially available under a trade name such as "9", is preferably used in the present invention.

In the present invention, the base resin of the cover is the above-mentioned ionomer resin of the component (A), the acid-modified thermoplastic elastomer of the component (B) or the thermoplastic elastomer having an -OH group added to the terminal, and the component (C). Epoxidized SBS
The composition for a cover, which is mainly composed of a heated mixture with a block copolymer having a structure or an SIS structure, has a flexural rigidity of 50 to 300 MPa and a Shore D
The hardness needs to be 40-60. When the bending stiffness of the cover composition is lower than 50 MPa, the cover becomes too soft and the spin rate increases too much, so that the flight distance is reduced, and the cut resistance is reduced, and the bending stiffness is higher than 300 MPa. If it is too high, an appropriate amount of backspin cannot be obtained, resulting in poor controllability and poor shot feeling. Further, when the Shore D hardness of the cover composition is lower than 40, the cover becomes too soft and cut resistance deteriorates. When the Shore D hardness is higher than 60, an appropriate back spin amount is obtained. As it disappears, the controllability deteriorates and the shot feeling also deteriorates.

The cover composition comprises an ionomer resin as the component (A), an acid-modified thermoplastic elastomer as the component (B) or a thermoplastic elastomer having a terminal —OH group added thereto, and an epoxidized SBS structure as the component (C). Alternatively, a heated mixture with a block copolymer having an SIS structure occupies a major part, and in many cases, only a small amount of titanium dioxide or barium sulfate is added thereto, so that its flexural rigidity and Shore D hardness are substantially (I) an ionomer resin as the component (A), an acid-modified thermoplastic elastomer as the component (B) or a thermoplastic elastomer having an -OH group added to the terminal, and an epoxidized SBS or SIS block copolymer as the component (C). Is almost the same as the flexural rigidity and Shore D hardness of the heated mixture.

In the present invention, the ionomer resin of the component (A), the acid-modified thermoplastic elastomer of the component (B) or the thermoplastic elastomer having a terminal —OH group added thereto, and the epoxidized SBS or SIS structure of the component (C) are used. Upon mixing with the block copolymer of
(A) 30 to 90% by weight of the ionomer resin of the component;
1 to 49% by weight of the acid-modified thermoplastic elastomer of the component (B) or the thermoplastic elastomer having a terminal -OH group added, and the epoxidized SBS structure or SIS of the component (C).
The block copolymer having the structure is preferably 1 to 49% by weight. When the amount of the ionomer resin of the component (A) is larger than the above range, the softening cannot be sufficiently achieved, and the properties of the ionomer resin appear strongly, and the shot feeling and controllability may be deteriorated. If the ionomer resin is less than the above range, the cover becomes too soft, and the spin amount increases too much, so the flight distance decreases,
In addition, the cut resistance may be reduced. (B)
Component acid-modified thermoplastic elastomer or -OH at the end
When the amount of the thermoplastic elastomer to which the group is added is less than the above range, the softening of the ionomer resin cannot be sufficiently achieved, and the shot feeling and controllability may not be sufficiently improved. If the amount of the thermoplastic elastomer or the thermoplastic elastomer having a terminal -OH group added is more than the above range, the cover may be too soft and the cut resistance may be deteriorated. And
When the epoxidized SBS structure or SIS structure block copolymer of the component (C) is less than the above range, (A)
The softening of the ionomer resin of the component cannot be achieved sufficiently,
The shot feeling and controllability may not be sufficiently improved, and the epoxidized SBS structure of component (C) or S
When the amount of the block copolymer having the IS structure is larger than the above range, the epoxy content is increased, and the ionomer resin as the component (A) or the acid-modified thermoplastic elastomer as the component (B) or the thermoplastic resin having a terminal —OH group added to the terminal. There is a possibility that the reaction amount with the elastomer becomes too large, the fluidity becomes poor, and the molding of the ball becomes difficult.

In the present invention, the ionomer resin of component (A), the acid-modified thermoplastic elastomer of component (B) or the thermoplastic elastomer having a terminal —OH group added thereto, and the epoxidized SBS structure of component (C) are used. Desired characteristics can be obtained based on the heating and mixing with the block copolymer having the SIS structure. The heating and mixing are usually performed by using an kneading type twin-screw extruder, Banbury, kneader or the like. Using a null mixer, for example,
This is performed by heating and mixing at 150 to 260 ° C.

In the present invention, the cover composition for forming the cover includes the above-mentioned ionomer resin (A) and the acid-modified thermoplastic elastomer (B) or a thermoplastic resin having a terminal —OH group added to the terminal. Elastomer and (C)
In addition to the heated mixture with the epoxidized SBS-structure or SIS-structure block copolymer of the components, if necessary, various additives such as pigments, dispersants, antioxidants, ultraviolet absorbers, light stabilizers, etc. Can be added. The component (A) is an ionomer resin, the component (B) is an acid-modified thermoplastic elastomer or a thermoplastic elastomer having a terminal -OH group added thereto, and the component (C) is an epoxidized SBS or SIS structure. Other resins may be added within a range that does not impair the properties of the heated mixture with the union. When the other resin is added as the base resin for the cover, the ionomer resin of the component (A) and the acid-modified thermoplastic elastomer of the component (B) or the thermoplastic elastomer having a terminal —OH group added to the terminal are used. The heated mixture of the component (C) and the epoxidized SBS or SIS block copolymer is preferably at least 70% by weight, particularly preferably at least 80% by weight. In the present invention, the ionomer resin of component (A), the acid-modified thermoplastic elastomer of component (B) or the thermoplastic elastomer having a terminal -OH group added thereto, and the epoxidized SBS or SIS structure block of component (C) are used. The fact that the heated mixture with the copolymer is the main component of the base resin of the cover means that the base resin of the cover is the ionomer resin of the component (A) and the acid-modified thermoplastic elastomer of the component (B) or -OH at the terminal. The base material of the cover comprising a heated mixture of the thermoplastic elastomer to which the group is added and the epoxidized SBS structure or SIS structure block copolymer of the component (C) alone, or by adding another resin to the heated mixture. It is meant to include both when resin is used. In the present invention, the ionomer resin (A) and the acid-modified thermoplastic elastomer (B) or the thermoplastic elastomer having an -OH group added to the terminal and the epoxidized SBS structure (SIS) of the component (C) are used. The heated mixture with the block copolymer having the structure may be mixed in advance by heating and then mixed with other additives, or may be mixed by heating together with other additives when preparing the cover composition. You may.

The thread-wound core comprises a center and a thread rubber layer formed by winding thread rubber around the center in a stretched state. The center is a solid formed of a vulcanized molded product of a rubber composition. It may be a center or a liquid center in which liquid such as water or paste is sealed in a center cover made of vulcanized rubber. In the case of a solid center, the diameter is 28 to 38 mm, and the amount of deformation from when an initial load of 10 kg is applied to when the final load is 30 kg is 0.5 to 2.5 mm. Preferably, there is. When the diameter of the solid center is smaller than 28 mm, the launch angle is small and the spin amount is increased, so that the flight distance may be difficult to be obtained.When the diameter of the solid center is larger than 38 mm, when winding the rubber thread, The thread rubber may be wound before the thread rubber is tensioned, so that the resilience of the thread rubber layer may not be sufficiently utilized, and the resilience performance of the ball may be reduced, making it difficult to obtain a flight distance. Also, when the deformation amount of the solid center is smaller than 0.5 mm, the shot feeling when the ball is made to be poor because the center is too hard, and when the deformation amount of the solid center is larger than 2.5 mm,
Since the center becomes too soft, it is difficult to obtain an appropriate ball hardness, and the initial ball speed may be reduced. In the case of a liquid center, the diameter is preferably 26 to 34 mm. When the diameter of the liquid center is smaller than 26 mm, the launch angle is small and the spin rate is increased, so that the flight distance may be difficult to be obtained. When the diameter of the liquid center is larger than 34 mm, the desired ball hardness is obtained. Not only is it difficult to remove the ball, but also the thread rubber layer becomes thin, so that the resilience performance of the ball is reduced and the flight distance may not be easily obtained.

The thread rubber may be the same as that conventionally used. For example, natural rubber or a blend rubber of natural rubber and synthetic polyisoprene may be added to an anti-aging agent, a vulcanization accelerator, and sulfur. A rubber composition obtained by vulcanizing a rubber composition containing the same can be used.

The method of covering the wound core with the cover is not particularly limited, and can be performed by a usual method. For example, the block copolymer of the ionomer resin (A), the acid-modified thermoplastic elastomer (B) or the thermoplastic elastomer having an -OH group added to the terminal and the epoxidized SBS structure or SIS structure (C). The cover composition containing the heated mixture with the coalesced is preliminarily formed into a hemispherical shell-like half shell, and the wound core is wrapped by using two of the half shells and pressure-formed at 130 to 170 ° C. for 1 to 5 minutes, or Alternatively, a method is employed in which the cover composition is directly injection-molded onto a wound core to wrap the wound core. The thickness of the cover is usually about 1 to 4 mm. Then, at the time of molding the cover, dimples are formed on the ball surface as necessary, and at the time of molding the cover, paint finishing, stamping, and the like are performed as necessary.

FIG. 1 is a cross-sectional view schematically showing one example of the golf ball of the present invention. In the figure, reference numeral 1 denotes a thread wound core comprising a center 1a and a rubber thread layer 1b, 2 denotes a cover,
2a is a dimple. As the center 1a,
The cover 2 may be a solid type or a liquid type. The cover 2 covering the solid type or the liquid type is composed of the ionomer resin of the component (A) and the acid-modified thermoplastic elastomer of the component (B) or a thermoplastic resin having an -OH group added to a terminal. Elastomer and (C)
Flexural rigidity including a heated mixture with an epoxidized SBS structure or SIS structure block copolymer as a component is 50 to 50%.
It was formed from a cover composition having a Shore D hardness of 40 to 60 at 300 MPa.

The dimples 2a are provided on the cover 2 in an appropriate number and in an appropriate form so that required or desired characteristics can be obtained. Is applied.

[0040]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

Examples 1 to 22 and Comparative Examples 1 to 8 The golf balls of Examples 1 to 22 and Comparative Examples 1 to 8 were produced through the following steps.

Preparation of a wound core: -a Preparation of a solid center A rubber composition having the compositions a, b and c shown in Table 1 is prepared, filled in a mold and vulcanized at 165 ° C. for 20 minutes. Thereby, three types of solid centers were produced. The amount of each component in Table 1 is based on parts by weight, the polybutadiene used was BR-11 (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd., and the antioxidant was manufactured by Yoshitomi Pharmaceutical Co., Ltd. Yoshinox 425 (trade name). Table 1 shows the weight, diameter, and amount of deformation of the obtained solid center (the amount of deformation from when the initial load of 10 kg is applied to the solid center to when the final load is applied with 30 kg).

[0043]

[Table 1]

-B Preparation of Liquid Center A liquid center was prepared using a rubber composition for a center cover and a paste having the compositions shown in Table 2. The amounts of each component in Table 2 are based on parts by weight.

In preparing the liquid center, first, a paste shown in Table 2 was poured into a mold cooled by a refrigerant and frozen to prepare a spherical core having a diameter of 24.5 mm.

Next, a rubber composition for a center cover having the composition shown in Table 2 was formed into a sheet, the sheet was covered with the above-mentioned frozen spherical core, punched out, and placed in a mold at 155 ° C. Vulcanization molding for 30 minutes, diameter 28.1m
m liquid centers were prepared. Table 2 shows the weight and diameter of the obtained liquid center.

[0047]

[Table 2]

Next, a yarn made of a blend rubber in which the base rubber is natural rubber / low cis-isoprene rubber [Shell IR-309 (trade name), manufactured by Shell Chemical Co.] = 30/70 (weight ratio) in each of the above centers. By winding the rubber in a stretched state to form a thread rubber layer, a thread wound core having an outer diameter of about 39 mm was produced. When a liquid center was used as the center, the liquid center was frozen before winding the thread rubber.

The obtained solid center wound cores were used for producing the golf balls of Examples 1 to 12 and Comparative Examples 1 to 4, and the liquid center wound cores of Examples 13 to 22 and Comparative Examples 5 to 5 were used. 8 used to produce the golf ball.

Preparation of cover composition: The compounding materials having the compositions shown in Tables 3 to 5 were mixed by a twin-screw kneading extruder to prepare a pellet-shaped cover composition. Table 3-
The blending amounts in Table 5 are based on parts by weight, and are shown in Tables 3 to 5
Table 5 shows details of items indicated by product names.

The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, a screw L / D = 35, and the compound was heated to 220 to 260 ° C. at the die position of the extruder. Then, the flexural rigidity and Shore D hardness of the obtained cover composition were measured. The measurement of the flexural rigidity was performed by preparing a hot-pressed sheet having a thickness of about 2 mm from each cover composition and storing it at 23 ° C. for 2 weeks.
The measurement of Shore D hardness was performed according to ASTM D-747, and a hot press-molded sheet having a thickness of about 2 mm was prepared from each cover composition, and stored at 23 ° C. for 2 weeks.
Performed according to STM D-2240. Tables 3 to 5 show the results together with the composition of the cover composition. In addition,
Cover compositions A to J whose compositions are shown in Tables 3 and 4 are used for golf balls of Examples, and cover compositions K and N whose compositions are shown in Table 5 are used for golf balls of Comparative Examples. Is what you do.

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

* 1: Himilan 1605 (trade name) Ethylene-methacrylic acid copolymer ionomer resin of neutralization type with sodium ion manufactured by DuPont-Mitsui Polychemicals Co., Ltd., MI (melt index) = 2.8, flexural rigidity = 310 MPa, Shore D hardness = 62 * 2: Himilan 1706 (trade name) Ethylene-methacrylic acid copolymer ionomer resin of zinc ion neutralization type manufactured by Du Pont-Mitsui Polychemicals, MI = 0.8, flexural rigidity Rate = 260 MPa, Shore D hardness = 61 * 3: Himilan 1855 (trade name) Zinc ion neutralized type ethylene-butyl acrylate-methacrylic acid terpolymer copolymer ionomer resin manufactured by Mitsui DuPont Polychemicals, MI = 1.0, flexural rigidity = 90 MPa, Shore D hardness = 55 4: Surlyn AD8511 (trade name) manufactured by DuPont zinc ion-neutralized type ethylene - methacrylic acid copolymer ionomer resin, MI = 3.4,
Flexural rigidity = 220 MPa, Shore D hardness = 60 * 5: Surlyn AD8512 (trade name) Sodium ion-neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by DuPont, MI =
4.4, flexural rigidity = 280 MPa, Shore D hardness =
62

* 6: Nucrel AN4212C (trade name) ethylene-isobutyl acrylate-methacrylic acid ternary copolymer resin manufactured by Du Pont-Mitsui Polychemical Co., Ltd. [polymerization composition ratio: 76/20/4 (weight ratio)], MI = 12, Shore D hardness = 30 * 7: Nucrel AN0825J (trade name) Ethylene-isobutyl acrylate-methacrylic acid terpolymer resin manufactured by Du Pont-Mitsui Polychemicals Co., Ltd. [Polymerization ratio: 72/20/8] (Weight ratio)], MI = 25, Shore D hardness = 25 * 8: AR-201 (trade name) Graft-modified maleic anhydride of an ethylene-ethyl acrylate copolymer manufactured by DuPont Mitsui Polychemicals, Inc. JIS-A hardness = 51 * 9: Bondine AX8390 (trade name) Sumitomo Chemical Co., Ltd. ethylene-ethylene Acrylate-maleic anhydride terpolymer, MI = 7.0, Shore D hardness = 14, ethyl acrylate + maleic anhydride content = 32% (including maleic anhydride 1-4%)

* 10: ESBS A1005 (trade name) Styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group, manufactured by Daicel Chemical Industries, Ltd., JIS-A hardness = 70, styrene / butadiene = 40/60 (weight ratio), epoxy content about 0.7 to 0.9% by weight * 11: ESBS A1010 (trade name) Styrene-butadiene having an epoxy group-containing polybutadiene block manufactured by Daicel Chemical Industries, Ltd. -Styrene block copolymer, JIS-A hardness = 67, styrene / butadiene = 40/60 (weight ratio), epoxy content about 1.5 to 1.7% by weight * 12: ESBS AT018 (trade name) Daicel Chemical Styrene-butyl hydrogenated to a part of polybutadiene block containing epoxy group manufactured by Kogyo Co., Ltd. Tadiene-styrene block copolymer, JIS-A hardness = 70, styrene / butadiene = 40/60 (weight ratio), epoxy content about 0.7-0.9% by weight * 13: ESBS AT019 (trade name) Daicel Chemical Styrene-butadiene-styrene block copolymer obtained by partially hydrogenating an epoxy group-containing polybutadiene block manufactured by Kogyo Co., Ltd., JIS-A hardness = 67, styrene / butadiene = 40/60 (weight ratio), epoxy Content: about 1.5 to 1.7% by weight * 14: ESBS A1020 (trade name), a styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group, manufactured by Daicel Chemical Industries, Ltd., JIS-A Hardness = 65, styrene / butadiene = 40/60 (weight ratio), epoxy content about 2.9-3.4% by weight

* 15: Himilan AM7317 (trade name) Zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Du Pont-Mitsui Polychemicals Co., Ltd., MI = 1.2, flexural rigidity = 310 MPa, Shore D hardness = 64 * 16: XE-1403 (trade name) Crystalline thermoplastic elastomer of maleic anhydride-modified thermoplastic elastomer manufactured by Kuraray Co., Ltd., hard segment is crystalline polyolefin, soft segment is amorphous polyolefin block Polymer, JIS-A hardness = 6
0 * 17: HG-252 (trade name) Kuraray Co., Ltd. hydrogenated styrene-isoprene-styrene block copolymer with an -OH group added to the terminal, JI
SA hardness = 80, styrene content: 40% by weight * 18: Surlyn AD8269 (trade name) Zinc ion neutralized type ethylene-butyl acrylate-methacrylic acid terpolymer copolymer ionomer resin manufactured by DuPont, MI = 1 0.0, flexural rigidity = 26 MPa, Shore D hardness = 36

Preparation of Golf Ball: A hemispherical shell half shell was formed from the above cover composition,
The above-mentioned wound core is wrapped in a single piece, and pressed in a ball mold at 150 ° C. for 2 minutes, the wound core is covered with a cover, and the surface is painted with paint to obtain an outer diameter of 4 mm.
A 2.8 mm golf ball was produced. Tables 6 to 12 show the combinations of the center and the cover used in producing the golf ball, together with the physical properties of the ball described below.

The ball weight, ball initial speed, flight distance (carry) and spin rate of the obtained golf ball were measured. The ball initial velocity is based on the R & A initial velocity measurement method.
Flying distance is attached to the No.1 wood club on a swing robot manufactured by True Temper, and the ball is head speed 45m.
The spin amount was measured by hitting the ball at a head speed of 34 m / s, and the mark on the hit ball was recorded at a high speed. Measured by taking a picture with a camera.

Examples 1 to 22 and Comparative Examples 1 to 8
In order to evaluate the cut resistance of the golf ball, a pitching wedge was attached to a swing robot manufactured by True Temper, and the ball was hit at the top with a head speed of 30 m / s. The evaluation criteria are as follows.

Evaluation criteria :: No cut flaw was generated △: Small cut flaw was generated ×: Large cut flaw was generated

Further, in order to evaluate the durability of the golf ball, a No. 1 wood club was attached to a swing robot manufactured by True Temper, and the ball was moved at a head speed of 45.
It was launched at m / s, and the number of times until breakage occurred was examined.
The result is indicated by an index when the number of times of impact resistance (number of times until breakage occurs) of Comparative Example 1 is set to 100.

The shot feeling and controllability of the obtained golf balls were evaluated by an actual hit test by 10 top professionals. The evaluation criteria are as follows. When displaying the evaluation results in the table, the same symbols are used,
In this case, it is indicated that eight or more out of the ten persons who made the evaluation gave the same evaluation.

Evaluation criteria: ：: Good hitting feeling and controllability similar to balata cover, good. Δ: The controllability is close to the balata cover, but the shot feeling is far apart. That is, it is too hard and the impact is too strong, or too soft and heavy. ×: Both shot feeling and controllability are poor.

The measurement results of the physical properties of the golf balls of Examples 1 to 12 and Comparative Examples 1 to 4 are shown in Tables 6 to 9, wherein the type of center and the type of cover (cover composition), flexural modulus, and shore were used. It is shown together with D hardness. Examples 13 and 2
Tables 9 to 12 show those of the golf balls of Comparative Example 2 and Comparative Examples 5 to 8. When a solid center is used, its composition is indicated by symbols a, b, and c (see Table 2).

[0067]

[Table 6]

[0068]

[Table 7]

[0069]

[Table 8]

[0070]

[Table 9]

[0071]

[Table 10]

[0072]

[Table 11]

[0073]

[Table 12]

As shown in Tables 6 to 8 and 10 to 11, the golf balls of Examples 1 to 22 had good shot feeling and controllability, regardless of the solid center and the liquid center, and exhibited good spin The amount is moderately large, the spin performance is good, and the flight distance is 232 to 2
36 yards, showing a flight distance almost equal to that of the golf balls of Comparative Examples 1 and 5 using only a high-rigidity ionomer resin as a base resin, and a sufficiently satisfactory cut resistance. Had been reached. Further, with respect to the durability, the golf balls of Examples 1 to 22 were at considerably higher levels than the golf balls of Comparative Example 1 and Comparative Example 5.

On the other hand, the golf balls of Comparative Examples 1 and 5 using only the high-rigidity ionomer resin as the base resin showed the flight performance, as shown in Tables 8 and 11.
Although the cut resistance was good, the shot feeling and controllability were poor. Further, only golf balls of Comparative Examples 2 to 3 and Comparative Examples 6 to 7 using a combination of a high-rigidity ionomer resin and a soft ionomer resin of a terpolymer type and a soft ionomer resin of a terpolymer type were combined. The golf balls of Comparative Example 4 and Comparative Example 8 used were inferior to the golf balls of Examples 1 to 22 in hit feeling, controllability, durability, etc., and also had a flight distance of Example 1.
~ 22 golf balls.

[0076]

As described above, according to the present invention, a golf ball having a multi-layered structure having a thread rubber layer has satisfactory hitting feel and controllability, and satisfactory flight performance and cut resistance. In addition, a golf ball having excellent durability can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of a golf ball of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wound core 1a Center 1b Thread rubber layer 2 Cover

Claims (8)

[Claims] 1. A golf ball having a wound core and a cover for covering the wound core, wherein the base resin of the cover is an ionomer resin and an acid-modified thermoplastic elastomer or a thermoplastic elastomer having an -OH group added to a terminal. And a styrene-butadiene-styrene block copolymer having an epoxy group-containing polybutadiene block or a styrene-isoprene-styrene block copolymer having an epoxy group-containing polyisoprene block as a main component. The flexural rigidity of the cover composition constituting the cover is 50 to 300.
A golf ball having a MPa and a Shore D hardness of 40 to 60. 2. An ionomer resin obtained by neutralizing at least a part of a carboxyl group in a copolymer of ethylene and acrylic acid or methacrylic acid with a metal ion, and / or ethylene and acrylic acid or methacrylic acid and α. At least some of the carboxyl groups in a terpolymer of α, β-unsaturated carboxylic acid ester are neutralized with metal ions, and the base polymer is a copolymer of ethylene and acrylic acid or methacrylic acid. The acid content is 10 to 20% by weight in the case of coalescing, and the acid content is 5 in the case of the terpolymer of ethylene and acrylic acid or methacrylic acid and α, β-unsaturated carboxylic acid ester.
2. The golf ball according to claim 1, wherein the amount is from 20 to 20% by weight. 3. An ionomer resin wherein at least a part of carboxyl groups in a copolymer of ethylene and acrylic acid or methacrylic acid is neutralized with a metal ion, and has a melt index of 3 to 7, The golf ball according to claim 1, wherein the golf ball is a so-called high-rigidity high-flow type having a flexural rigidity of 200 to 400 MPa. 4. The golf ball according to claim 1, wherein the acid-modified thermoplastic elastomer is a maleic anhydride-modified thermoplastic elastomer. 5. The golf ball according to claim 1, wherein the acid-modified thermoplastic elastomer is a terpolymer of ethylene, an unsaturated carboxylic acid ester and an unsaturated carboxylic acid. 6. A structure in which a thermoplastic elastomer having a terminal —OH group added thereto is hydrogenated to a double bond of a butadiene portion in a styrene-butadiene-styrene block copolymer having a terminal —OH group added or a terminal. The golf ball according to claim 1, which is a block copolymer having a structure in which hydrogen is added to a double bond of an isoprene portion in a styrene-isoprene-styrene block copolymer in which a -OH group is added to the block copolymer. 7. The thread-wound core comprises a center and a thread rubber layer formed by winding thread rubber around the center, wherein the center is a solid center and has a diameter of 2 mm.
8 to 38 mm, and the amount of deformation from when an initial load of 10 kg is applied to when a final load of 30 kg is applied is 0.5 to
The golf ball according to claim 1, 2, 3, 4, 5, or 6, which is 2.5 mm. 8. A thread wound core comprising a center and a thread rubber layer formed by winding thread rubber around the center,
7. The golf ball according to claim 1, wherein the center is a liquid center and has a diameter of 26 to 34 mm.