JPH11319150A - Cover material for golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently maintain whiteness without the impairment of white appearance even when a cover surface is peeled by toning a cover material for a golf ball consisting of an ionomer resin and diene-base rubber by using a brightening agent, titanium oxide, etc. SOLUTION: The cover material for the golf ball consisting of the ionomer resin and the diene-base rubber is toned by using the brightening agent, the titanium oxide, etc. The ionomer resin consists of an ehylenically unsatd. carboxylic acid copolymer as a base resin and is obtainable from, for example, a metal compd. capable of supplying cation with the ehylenically unsatd. carboxylic acid copolymer. For example, natural rubber, butadiene, etc., may be used as the diene-base rubber. The titanium oxide is incorporated into the cover material for the golf ball in order to make the ball white. In addition, the brightening agent is incorporated into the cover material in order to make the white of the titanium oxide conspicuous. The incorporation of an org. peroxide, such as sulfur, therein is possible as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball cover material having excellent weather resistance and lightness. This cover material is useful as a cover material constituting a cover of a golf ball.

[0002]

2. Description of the Related Art Conventionally, a cover of a golf ball having a core covered with a cover is composed of a cover material comprising an ionomer resin as a main component and a diene rubber blended with the cover material. The control, flight performance and cut resistance are improved. However, a cover made of such a cover material is not sufficient in terms of whiteness.

[0003] Therefore, the surface of the cover of the golf ball,
The surface finish of the golf ball is performed by applying a primer paint, applying an enamel paint having a white pigment such as titanium dioxide thereon, and further applying a transparent clear paint thereon. However,
When the paint surface finish of the golf ball is performed in this manner, there is a problem that the cover surface is exposed due to paint peeling or the like, and the white appearance is impaired.

In Japanese Patent Application Laid-Open No. 10-66741, a diene rubber is cross-linked by using sulfur as a cross-linking agent in a golf ball cover material comprising an ionomer resin and a diene rubber. Not enough white is needed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cover for a golf ball, which is used as a cover material, so that the white appearance is not impaired even when the cover surface is exposed due to paint peeling or the like. An object of the present invention is to provide a golf ball cover material having a sufficient whiteness.

[0006]

SUMMARY OF THE INVENTION A golf ball cover material comprising an ionomer resin and a diene rubber is toned with a fluorescent whitening agent, titanium oxide or the like to provide a golf ball cover material having sufficient whiteness. It is possible to do. Preferably, the diene rubber is thermally crosslinked without using a crosslinking agent.

[0007] As described above, since the cover material is given an appropriate white color because the color is toned using a fluorescent whitening agent, titanium oxide, or the like, even if the cover surface is exposed due to paint peeling or the like, the cover material is not removed. The peeled part is not noticeable,
And the white appearance is not impaired. In addition, since the cover material contains titanium oxide and a fluorescent whitening agent, it is only necessary to apply a clear paint to protect the cover when finishing the paint surface of the golf ball. The application work is easier than when paint and clear paint are applied sequentially.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The ionomer resin is ethylene-
It is based on an unsaturated carboxylic acid-based copolymer and can be obtained, for example, from an ethylene-unsaturated carboxylic acid-based copolymer and a metal compound capable of supplying a cation. The ethylene-unsaturated carboxylic acid copolymer is, for example, a copolymer of ethylene and an unsaturated carboxylic acid having 3 to 6 carbon atoms, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, or vinyl benzoate. It is.

Metal compounds capable of supplying cations include, for example, formate, acetate, nitrate, carbonate, bicarbonate, oxide, hydroxide of alkali metals, alkaline earth metals, transition metals and the like. Alkoxide and the like. Examples of the type of metal include Na, Zn, Li, Mg, Mn, Ca, Co, and K.

As the ionomer resin, for example,
A metal salt of a copolymer of ethylene and methacrylic acid is exemplified. This ionomer resin may be a commercially available one, for example, Himilan 1605, Himilan 1706, and Himilan 17 manufactured by Mitsui DuPont Polychemicals.
07, High Milan AM7315, High Milan AM731
7, Himilan AM7318, Surlyn 7930 and Surlyn 7940 manufactured by DuPont.

Examples of the diene rubber include natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), and styrene-butadiene copolymer rubber (SB).
R), ethylene-propylene-diene copolymer rubber (E
PDM), acrylonitrile-butadiene copolymer rubber, or the like. Of these, it is preferable to use butadiene rubber. As the butadiene rubber, a commercially available product may be used, but it is preferable to use one having a cis-1,4 structure of 40% or more.

The golf ball cover material of the present invention contains titanium oxide to give a white color. The titanium oxide is blended in an amount of 1 to 5 parts by weight based on 100 parts by weight of the ionomer resin.

[0013] The golf ball cover material of the present invention contains a fluorescent whitening agent to make the titanium oxide whiter (to make it look whiter). The fluorescent whitening agent is not particularly limited, and includes, for example, methylated stilbene bisbenzoxazole derivatives, pyrene derivatives, coumarin, naphthalimide and the like. preferable. The methylated stilbene bisbenzoxazole derivative is a compound having the following formula, specifically, 4- (2-benzoxazolyl) -4 ′
-(5-methyl-2-benzoxazolyl) stilbene, 4,4'-
Bis (5-methyl-2-benzoxazolyl) stilbene and the like.

[0014]

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The fluorescent whitening agent is an ionomer resin 10
0.01 parts by weight to 0.03 parts by weight per 0 parts by weight. The golf ball cover material of the present invention may further contain, if necessary, a bluing agent in addition to the titanium oxide and the fluorescent whitening agent. This is because the whiteness of the whitening agent is further enhanced by the bluishness of the bluing agent. Examples of the bluing agent include phthalocyanine blue and indanthrone blue.

Further, the golf ball cover material of the present invention may contain a crosslinking agent such as sulfur or an organic peroxide. As the cross-linking agent, it is preferable to use an uncolored or white one. Furthermore, you may contain the compatibilizer which has a part compatible or reacting with both an ionomer resin and a diene rubber. The compatibilizer is, for example, a polymer containing maleic anhydride as a constituent, a polymer containing an oxazoline group as a constituent, or a polymer containing a glycidyl group as a constituent. It is preferable to use an uncolored or white compatibilizing agent. The diene rubber may be dynamically crosslinked.

The cover material for a golf ball of the present invention is an ionomer resin having a Shore D hardness of 55 or more and less than 80.
It is preferable that the composition is composed of 95 parts by weight and 5 to 50 parts by weight of the diene rubber, wherein the diene rubber is dispersed in the ionomer resin with a particle diameter of 5 μm or less. With this configuration, the golf ball's flight performance (rebound), hit feeling,
This is because spin performance is further improved.

This ionomer resin has a Shore D hardness of 55 or more and less than 80 (55 ≦ Shore D hardness <8).
0). The Shore D hardness is set to 55 or more because the higher the hardness of the ionomer resin, the higher the rebound resilience. If the Shore D hardness is 80 or more, even if a diene rubber is mixed, the effect is not obtained, and the shot feeling of the obtained golf ball becomes too hard.

The composition constituting the cover material comprises 50 to 95 parts by weight of the ionomer resin and 5 to 50 parts by weight of the butadiene rubber. If the amount of the ionomer resin is less than 50 parts by weight, the hardness of the cover decreases and the shot feeling is too soft. On the other hand, if it exceeds 95 parts by weight, the softening by the diene rubber becomes insufficient and the shot feeling is too hard. I will.

Further, in this composition, the diene rubber is dispersed in the ionomer resin with a particle diameter of 5 μm or less. The particle size is preferably from 0.1 μm to 5 μm
It is good. This is because by making the particle diameter as small as 5 μm or less, resilience, durability and appearance are improved.
In this composition, the diene rubber is preferably thermally crosslinked. Here, thermal crosslinking means that the uncrosslinked diene rubber is crosslinked only by heat without using a crosslinking agent (crosslinking is performed only by heating). If the diene rubber is not thermally crosslinked, the resilience, durability, and appearance of the cover will deteriorate. Here, the deterioration of the appearance means that the cover is fluffed and the appearance is deteriorated.

In order to produce the above composition constituting the cover material, the ratio of the viscosity of the ionomer resin at the melting temperature of the ionomer resin to the viscosity of the diene rubber at the same temperature (diene rubber / ionomer resin) is determined. An ionomer resin and a diene rubber of 1/1 to 5/1 are mixed with the ionomer resin 5 at a melting temperature of the ionomer resin (130 ° C. to 260 ° C.).
It is advisable to mix the diene rubber in a ratio of 10 to 50 parts by weight with respect to 0 to 90 parts by weight. Thereby, the diene rubber can be dispersed in the ionomer resin with a particle size of 5 μm or less.

When the viscosity ratio is more than 5/1, the difference in viscosity between the ionomer resin and the diene rubber increases, and no shearing force is applied during mixing, so that the diene rubber does not disperse finely. On the other hand, when the viscosity ratio is smaller than 1/1, the viscosity of the ionomer resin becomes larger than that of the diene rubber, so that the ionomer resin has a structure in which the ionomer resin is finely dispersed in the diene rubber.
The mixing is preferably performed at a shear rate of 1000 / sec or more. If the shear rate is less than 1000 / sec, the diene rubber cannot have a particle size of 5 μm or less. As a mixer used for this mixing, it is preferable to use a twin-screw extruder.

[0023]

EXAMPLE A golf ball was produced by covering a spherical solid core having a diameter of 38.3 mm with a cover having a thickness of 2.3 mm made of a cover material having the composition (parts by weight) shown in Table 1 and covering the surface of the cover. Then, urethane clear paint was applied to finish the surface. The golf ball thus finished (Example 1, Comparative Examples 1 and 2) is JIS
Hue (whiteness, yellowness) was evaluated based on Z8701. Table 1 shows the results. In Table 1, "○" means good,
“X” indicates bad.

[0024]

[Table 1]

Note) * 1 Sodium ionic ethylene-methacrylic acid copolymer, Shore D, manufactured by DuPont-Mitsui Polychemicals
Hardness 67. * 2 Mitsui DuPont Polychemical Co., Ltd., zinc ion ethylene-methacrylic acid copolymer, Shore D hardness 6
6. * 3 Nippon Synthetic Rubber Co., Ltd., polybutadiene rubber, 1,4-cis structure 97%, Mooney viscosity 42. * 4 Hostalux KS-N Hoechst, optical brightener 4,4'-
Methylated bis (2-benzoxazolyl) stilbene.
Mainly 4,4'-bis (5-methyl-2-benzoxazolyl)
Contains stilbene and 4,4'-bis (2-benzoxazolyl) stilbene. As is clear from Table 1, in the case of the present invention (Example 1), it is found that the hue is superior to Comparative Examples 1 and 2.

[0026]

As described above, according to the present invention, the cover material for a golf ball comprises an ionomer resin and a diene rubber, and is toned with a fluorescent whitening agent and a toning agent containing titanium oxide. Therefore, even when the cover surface is exposed due to paint peeling or the like, the white appearance is not impaired, and the weather resistance and brightness can be improved.

Claims (4)

[Claims] 1. A golf ball cover material comprising an ionomer resin and a diene rubber and toned with a toning agent containing a fluorescent whitening agent and titanium oxide. 2. The golf ball cover material according to claim 1, wherein the diene rubber is crosslinked without using a crosslinking agent. 3. The golf ball cover material according to claim 1, wherein the diene rubber is butadiene rubber. 4. The fluorescent whitening agent has the following formula: 4. The golf ball cover material according to claim 1, which is a methylated stilbenebisbenzoxazole derivative having the following formula: