JP3478588B2 - Golf ball - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball having a core covered with a cover.

[0002]

2. Description of the Related Art As a main cover material for golf balls, ionomer resins have been widely used for imparting well-balanced required properties such as resilience, impact resistance and cut resistance to golf balls. On the other hand, in recent years, golfers' demands for golf balls have become diversified and advanced, and therefore, for the purpose of further improving the properties of conventional golf balls, it is performed to mix an ionomer resin with another polymer. ing.

For example, the applicant of the present invention uses a mixture of an ionomer resin and a saponified product of an ethylene-unsaturated carboxylic acid ester copolymer as a main component of a cover to improve the properties, particularly durability, of a golf ball obtained hitherto. A golf ball that can be improved is proposed (Japanese Patent Application No. 5-12009).
(See No. 5).

[0004]

By the way, when the ionomer resin and other polymers are mixed, unless a polymer having a good compatibility with the ionomer resin is selected, the mixture is dispersed in the polishing step during the production of a golf ball. There is an inconvenience that the cover is peeled off due to a defect.

The present invention has been made in order to overcome the above-mentioned inconvenience, and it is possible to improve the dispersibility of a mixture of an ionomer resin and another polymer without causing poor dispersion. Intended to provide the ball.

[0006]

SUMMARY OF THE INVENTION The present invention is a golf ball having a core covered with a cover, wherein the main material of the cover is A: a metal of ethylene- (meth) acrylic acid copolymer. and salt, B: ethylene - (meth) and saponified acrylic acid ester copolymer, C: a core-shell polymer, a mixture der of is, the C, the core is a conjugated diene or a
With the number of carbon atoms in the alkyl group consists of at least one of polymers of alkyl acrylates rate is 2-8,
The shell is made of at least one polymer of alkyl (meth) acrylate, aromatic vinyl, aromatic vinylidene, vinyl cyanide, vinylidene cyanide, or
And the mixture contains 50 to 93% by weight of the component A,
The B component 5-35 wt%, the pre-SL component C 2-15 wt%
It is characterized by containing . Further , the present invention is a golf ball having a cover covered with a core, wherein the main material of the cover is: A: a metal salt of ethylene- (meth) acrylic acid copolymer, and B: ethylene- (meth ) and saponified acrylic acid ester copolymer, C: a core-shell polymer, a mixture of the C is at least a core number of carbon atoms of the conjugated diene or an alkyl group of the alkyl acrylate is 2 to 8 both the one and the polymer and the copolymerizable monomer either ing copolymerized, shell alkyl (meth) acrylates, aromatic vinyl, aromatic vinylidene, vinyl cyanides, at least vinylidene cyanide
Ri Do either from one polymer, and said mixture, prior to
The component A is 50 to 93% by weight, and the component B is 5 to 35% by weight.
The amount%, characterized in that the pre-SL component C are those containing 2 to 15 wt%.

The main material of the cover of the golf ball according to the present invention comprises a metal salt of an ethylene- (meth) acrylic acid copolymer, which is an ionomer resin, as a constituent component.
The metal salt of the (meth) acrylic acid copolymer is ethylene-
Sodium, lithium, (meth) acrylic acid copolymer
It can be obtained by reacting with a compound such as an oxide, hydroxide, acetate, nitrate or carbonate of a metal such as zinc, calcium or magnesium.

In the present invention, the metal salt of ethylene- (meth) acrylic acid copolymer may be one kind or a mixture of two or more kinds which have been conventionally used for golf ball covers. You can

As an example of the metal salt of the ethylene- (meth) acrylic acid copolymer, the metal salt of the ethylene-methacrylic acid copolymer is "HIMILAN" manufactured by DuPont Mitsui Polychemicals Co., Ltd. Name), "SURLYN" manufactured by DuPont
(Trade name), as a metal salt of ethylene-acrylic acid copolymer, "IOTEK" manufactured by Exxon
(Product name).

The main material of the cover of the golf ball according to the present invention comprises a saponification product of ethylene- (meth) acrylic acid ester copolymer as a constituent component, and the saponification product of the ethylene- (meth) acrylic acid ester copolymer is , A copolymer obtained by the saponification reaction of an ethylene- (meth) acrylic acid ester copolymer with an alkali and containing ethylene, a (meth) acrylic acid ester and a (meth) acrylic acid alkali salt.

As the (meth) acrylic acid ester of the ethylene- (meth) acrylic acid ester copolymer, methyl (meth) acrylate, ethyl (meth) acrylate,
n-Butyl (meth) acrylate, isobutyl (meth)
Examples thereof include acrylate and t-butyl (meth) acrylate. In this case, it is particularly preferable to use methyl acrylate or ethyl acrylate in the present invention.

The main material of the cover of the golf ball according to the present invention comprises a core-shell type polymer as a constituent component, and the core-shell type polymer is obtained by at least two steps of polymerization reaction. The first stage forms the core and the second stage
The staged polymerization forms a shell on its outside.

The core is a polymer of a conjugated diene or an alkyl acrylate in which the alkyl group has 2 to 8 carbon atoms, or a mixture thereof. Examples of the conjugated diene include butadiene, isoprene, and chloroprene. Examples of the alkyl acrylate having an alkyl group having 2 to 8 carbon atoms include ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate. Although exemplified, butyl acrylate is particularly preferable.

Further, the core may be a copolymer of a monomer copolymerizable with a conjugated diene and an alkyl acrylate. Examples of the copolymerizable monomer include styrene, vinyltoluene, aromatic vinyl such as α-methylstyrene, vinylidene cyanide, vinyl cyanide such as (meth) acrylonitrile, vinylidene cyanide, methyl methacrylate and butyl methacrylate. It is illustrated.

The shell is formed by polymerizing a monomer containing no amino group, imino group, epoxy group, hydroxyl group, carboxyl group, carboxylate group, isocyanate group, sulfonic acid group, sulfonate group, or the like.
Examples of such a monomer include alkyl (meth) acrylates such as ethyl acrylate, methyl methacrylate, and butyl (meth) acrylate, aromatic vinyl such as styrene, vinyltoluene, and α-methylstyrene, and aromatic vinylidene, (meth). Examples thereof include vinyl cyanide such as acrylonitrile, vinylidene cyanide, and the like, and ethyl acrylate, methyl methacrylate, and butyl methacrylate are particularly preferable.

The core-shell type polymer may have a multi-layered core and / or shell, and in this case, it is obtained by a polymerization reaction of at least three steps.

In the present invention, a metal salt of an ethylene- (meth) acrylic acid copolymer (hereinafter referred to as component A),
A mixture of a saponification product of an ethylene- (meth) acrylic acid ester copolymer (hereinafter referred to as B component) and a core-shell type polymer (hereinafter referred to as C component) is used as a main material of the cover. In this case, although the compatibility is poor when the A component and the B component are mixed, the C which is excellent in the compatibility with the B component is used.
Mixing the components gives a mixture with good dispersibility.

The respective components A, B and C are mixed in the range of 50 to 93% by weight of the component A, 5 to 35% by weight of the component B and 2 to 15% by weight of the component C with respect to the whole mixture. Is preferred. A mixture in which each of the components A, B, and C is within the above range has good dispersibility, and the cover of the golf ball does not peel off in the polishing step when manufacturing a golf ball. If the amount of the C component is less than 2% by weight, the cover will peel off, and if it is more than 15% by weight, the resilience of the golf ball will be impaired.

The mixing amount of the above-mentioned A component and B component affects the characteristics such as resilience and impact resistance of the golf ball, and outside the above range, the resilience is impaired and the impact resistance is improved. I can't get it.

The golf ball of the present invention comprises the above A, B, C
The main component of the cover is a mixture of the above components, but if necessary, additives such as pigments, fluorescent whitening agents, antioxidants, ultraviolet absorbers, and ultraviolet stabilizers may be added.

[0021]

EXAMPLES The golf ball of the present invention will be described below with reference to examples and comparative examples.

[0022]

[Table 1]

First, a rubber composition having the composition shown in Table 1 was pressure-molded in a core mold to obtain a solid core having a diameter of 38.3 mm. Next, the obtained core was coated with a composition for a cover whose composition is shown in Tables 2 and 3 using an injection molding machine to obtain golf balls of Examples 1-11 and Comparative Examples 1-5. The diameter of the obtained golf ball was 42.80 mm.

The physical properties and characteristics of the golf balls of Examples 1 to 11 and Comparative Examples 1 to 5 were measured and shown in Tables 2 and 3, respectively.

[0025]

[Table 2]

[0026]

[Table 3]

In Tables 2 and 3, * 1 is an ethylene-methacrylic acid copolymer type ionomer resin (sodium ion neutralization type) manufactured by Mitsui DuPont Polychemical Co., Ltd., * 2 is Mitsui DuPont Polychemical Co., Ltd. The ethylene-methacrylic acid copolymer-based ionomer resin (zinc ion neutralization type), * 3, indicates core-shell polymers manufactured by Takeda Pharmaceutical Co., Ltd., respectively.

The initial velocity efficiency is a value obtained by dividing the initial velocity of the ball when hit by the No. 1 wood club using the swing robot device by the club head velocity. The larger this value, the better the resilience of the ball. Impact resistance is 23 ℃
The number of times until a crack was generated in the cover when repeatedly hit under the temperature of 1. The evaluation of appearance after polishing was indicated by "excellently good" by "A", "good" by "O" and "bad" by "X".

The golf ball of Comparative Example 1 had an initial velocity efficiency of 1.
In contrast to 454, the golf balls of Examples 1 to 11 had initial velocity efficiencies in the range of 1.448 to 1.454, which were almost the same. The golf ball of Comparative Example 5 had an initial velocity efficiency of 1.429 and was poor.

The golf balls of Examples 1 to 11 are
The impact resistance index was in the range of 114 to 143, and the impact resistance was improved as compared with the golf ball of Comparative Example 1.

Further, the golf balls of Examples 1 to 11 have good appearance evaluation after polishing. On the other hand, Comparative Example 2
The golf balls of Nos. 4 to 4 had poor appearance evaluation after polishing and had peeled off on the cover.

[0032]

The golf ball according to the present invention has a metal salt of ethylene- (meth) acrylic acid copolymer and ethylene- (meth) acrylic acid copolymer.
A mixture of a saponified product of a (meth) acrylic acid ester copolymer and a core-shell type polymer is used as a main material for the cover, and a mixture of a saponified product of an ethylene- (meth) acrylic acid ester copolymer and a core-shell type polymer is used. Allows the cover to be softened without impairing the good resilience of the metal salt of ethylene- (meth) acrylic acid copolymer, thus maintaining the conventionally obtained resilience and improving impact resistance. . Further, since the core-shell type polymer improves the dispersibility of the mixture,
The productivity can be improved without causing peeling of the cover in the polishing step during manufacturing.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-345051 (JP, A) JP-A-2-103244 (JP, A) JP-A-6-313075 (JP, A) JP-A-7- 148283 (JP, A) JP 6-319832 (JP, A) JP 6-327790 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A63B 37/00-37 / 14 C08L 23/26-23/36

Claims (5)

(57) [Claims] 1. A golf ball having a core covered with a cover, wherein the main material of the cover is: A: a metal salt of an ethylene- (meth) acrylic acid copolymer; and B: an ethylene- (meth). and saponified acrylic acid ester copolymer, C: a core-shell polymer, a mixture der of is, the C has a carbon number of cores conjugated diene or an alkyl group
Together but consists of at least one of polymers of alkyl acrylates rate is 2-8, shell alkyl (meth) acrylates, aromatic vinyl, aromatic vinylidene, vinyl cyanides, at least any one vinylidene cyanide The polymer, and the mixture contains 50 to 93% by weight of the component A,
A golf ball containing the component B in an amount of 5 to 35% by weight and the component C in an amount of 2 to 15% by weight. 2. A golf ball having a core covered with a cover, wherein the main material of the cover is A: a metal salt of ethylene- (meth) acrylic acid copolymer, and B: ethylene- (meth). It is a mixture of a saponified product of an acrylic ester copolymer and C: a core-shell type polymer, wherein C is at least one of a conjugated diene having a core or an alkyl acrylate having an alkyl group having 2 to 8 carbon atoms. both the one and the polymer and the copolymerizable monomer or it ing copolymerized, shell alkyl (meth) acrylates, aromatic vinyl, aromatic vinylidene, vinyl cyanides, any at least of vinylidene cyanide or one Ri Do from the polymer, and the mixture of the a component 50 to 93 wt%, prior
A golf ball containing the component B in an amount of 5 to 35% by weight and the component C in an amount of 2 to 15% by weight. 3. The golf ball according to claim 2 , wherein the monomer is aromatic vinyl, aromatic vinylidene or vinyl cyanide. 4. The golf ball according to claim 1, wherein B is a saponification product of an ethylene-ethyl acrylate copolymer. 5. The golf ball according to claim 1, wherein C is a polymer obtained by forming a methyl methacrylate polymer on the outside of a butyl acrylate polymer. ball.