JP5170374B2 - Golf ball - Google Patents

Description

  The present invention relates to a golf ball having a core and a cover of one or more layers. More specifically, the present invention relates to a golf ball having good shot feel and excellent scratch resistance while maintaining good flight performance. .

  In recent years, ionomer resins have been widely used as cover materials for golf balls. The ionomer resin is an ionic copolymer composed of an olefin such as ethylene and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid, partially with a metal such as sodium, lithium, zinc or magnesium. It is neutralized with ions, and has particularly excellent properties such as durability and resilience, and is suitable as a base resin for golf ball cover materials.

  At present, ionomer resins occupy the mainstream of cover resin, and golf balls with the above characteristics are manufactured. However, users always demand golf balls with high repulsion and excellent flight characteristics. Yes. As an example of such an improvement, U.S. Pat. No. 6,653,382 (Patent Document 1) and U.S. Pat. No. 6,815,480 (Patent Document 2) describe that a third component such as an alkyl acrylate is ethylene, It describes that a ternary copolymer copolymerized with a saturated carboxylic acid is used as a cover material. However, when oleic acid is added to this ternary copolymer, it becomes too soft as a golf ball, and there is an aspect that the initial velocity of the ball is lowered and the scratch resistance is deteriorated.

  In addition, US Pat. No. 6,762,246 (Patent Document 3) describes a material in which a low molecular weight compound such as a wax is mixed with a ternary ionomer, but the performance of the golf ball tends to decrease overall. It is in.

  On the other hand, it has also been proposed to use a low-hardness ionomer as a cover material in order to emphasize hit feeling. However, when a low hardness ionomer is used, the initial speed tends to decrease or the scratch resistance tends to deteriorate.

US Pat. No. 6,653,382 US Pat. No. 6,815,480 US Pat. No. 6,762,246

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a golf ball that can sufficiently satisfy not only flying performance but also hit feeling and scratch resistance characteristics.

  As a result of intensive studies to achieve the above object, the inventor of the present invention, in a golf ball having a core and a cover of one or more layers, at least one layer constituting the cover as a component (a) Neutralized metal ion of olefin-unsaturated carboxylic acid random copolymer having D hardness of 60 or more, (b) component, unsaturated fatty acid, (c) component, (a), (b) component acid By using a basic inorganic metal compound capable of neutralizing a group and mixing and molding these components (a) to (c) in a predetermined range amount, a ball resilience is obtained. It has been found that both the good hit feeling and the excellent scratch resistance property are imparted while maintaining the good condition, and the present invention has been made.

Accordingly, the present invention provides the following golf balls.
[1] A golf ball having a core and a cover of one or more layers, wherein the outermost layer constituting the cover has the following components (a) to (c) (a) Olefin-unsaturation having a Shore D hardness of 60 or more 100 parts by mass of a neutralized metal ion of a carboxylic acid random copolymer,
(B) 5-60 parts by mass of at least one unsaturated fatty acid selected from the group consisting of oleic acid, elaidic acid, erucic acid, linoleic acid and linolenic acid,
And (c) a basic inorganic metal compound capable of neutralizing acid groups in the components (a) and (b)
By forming a mixture having a melt mass flow rate of 1 to 10 parts by mass as an essential component of 2.0 g / 10 min or more, the Shore D hardness of the component (a) decreases in the range of 7 to 18 and Shore D A golf ball formed of a material having a hardness of 46 to 58.
[2] The golf ball of [1], wherein the basic inorganic metal compound as the component (c) is calcium hydroxide.

  According to the golf ball of the present invention, while maintaining good flight performance, it has both a good shot feel and excellent scratch resistance.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention has a core and a cover of one layer or a plurality of layers, and the core can be constituted not only by one layer but also by two or more layers if necessary.

  As the material of the core, a rubber composition obtained by adjusting vulcanization conditions, compounding ratio, and the like by an ordinary method is used. Usually, the blending of the core includes a base rubber, a crosslinking agent, a co-crosslinking agent, an inert filler and the like. In this case, natural rubber and / or synthetic rubber conventionally used for solid golf balls can be used as the base rubber. For example, 1,4-polybutadiene having at least 40% cis structure is used. . If desired, natural rubber, polyisoprene rubber, styrene butadiene rubber or the like can be appropriately blended with the polybutadiene. Examples of the crosslinking agent include organic peroxides such as dicumyl peroxide and di-t-butyl peroxide. Further, the co-crosslinking agent is not particularly limited, and examples thereof include metal salts of unsaturated fatty acids, particularly zinc salts and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms (for example, acrylic acid and methacrylic acid). The Furthermore, examples of the inert filler include zinc oxide, barium sulfate, silica, calcium carbonate, and zinc carbonate. In addition to the rubber composition described above, a thermoplastic resin such as an ionomer resin or a polyester elastomer, or a thermoplastic elastomer can be used as the solid core material.

  With respect to the solid core, a solid core can be produced by vulcanizing and curing the rubber composition containing each of the above components by a known method, for example, kneading using a kneader such as a Banbury mixer or a roll. , Compression molding or injection molding with a core mold, and the molded body at a temperature sufficient for the peroxide or co-crosslinking agent to act, for example using dicumyl peroxide as the peroxide and acrylic as the co-crosslinking agent In the case of using zinc acid, it is usually produced by curing the molded body by appropriately heating at about 130 to 170 ° C., particularly 150 to 160 ° C. for 10 to 40 minutes, particularly 12 to 20 minutes. be able to.

  Further, the hardness of the solid core is not particularly limited and can be adjusted as appropriate, and the hardness distribution may be substantially equivalent from the core center to the core surface. There may be a difference in hardness between the center and the core surface, and either case may be used.

  The diameter of the solid core is preferably 25 mm or more, particularly 36 mm or more, and the upper limit is preferably 42 mm or less, particularly 24 mm or less. Further, the weight is preferably 20 to 32 g, particularly 27 to 30 g.

In the present invention, at least one of the covers composed of one or more layers is formed from a material obtained by molding a mixture containing the following components (a) to (c) as essential components. .
(A) Metal ion neutralized product of olefin-unsaturated carboxylic acid random copolymer
100 parts by mass,
(B) 5-60 parts by mass of unsaturated fatty acid,
And (c) a basic inorganic metal compound capable of neutralizing acid groups in the components (a) and (b)
1-10 parts by mass.

  The olefin in the component (a) preferably has 2 or more carbon atoms, and the upper limit is preferably 8 or less carbon atoms, particularly preferably 6 or less carbon atoms, specifically ethylene, Examples include propylene, butene, pentene, hexene, heptene, octene and the like, and ethylene is particularly preferable.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and acrylic acid and methacrylic acid are particularly preferable.

  The random copolymer constituting the random copolymer metal salt as component (a) can be obtained by random copolymerizing the above components according to a known method. Here, the content (acid content) of the unsaturated carboxylic acid contained in the random copolymer is preferably 2% by mass or more, more preferably 6% by mass or more, still more preferably 8% by mass or more, preferably as an upper limit. Is 25% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less. If the acid content is low, the resilience may be reduced, and if it is high, the processability may be reduced.

Moreover, the metal ion neutralized product of the random copolymer of the component (a) can be obtained by partially neutralizing acid groups in the random copolymer with metal ions. Here, examples of metal ions that neutralize acid groups include Na ⁺ , K ⁺ , Li ⁺ , Zn ⁺⁺ , Cu ⁺⁺ , Mg ⁺⁺ , Ca ⁺⁺ , Co ⁺⁺ , Ni ⁺⁺ , and Pb. ^{++ and the} like can be mentioned, but Na ⁺ , Li ⁺ , Zn ⁺⁺ , Mg ^{++ and the} like are preferably used, and Zn ⁺⁺ is more preferable. The degree of neutralization of the random copolymer of these metal ions is not particularly limited. Such a neutralized product can be obtained by a known method. For example, for the random copolymer, the metal ion formate, acetate, nitrate, carbonate, bicarbonate, oxide, water It can be introduced using compounds such as oxides and alkoxides.

  Thus, in the present invention, a binary copolymer of a neutralized olefin-unsaturated carboxylic acid random copolymer is used as the component (a). The reason for this is that, in the present invention, in order to give the ball a soft feel and excellent scratch resistance, the metal ion neutralized product of the binary copolymer as component (a) will be described later. It is necessary to use unsaturated fatty acid, but the binary copolymer is easier to plasticize the entire cover material than the ternary copolymer, and good moldability can be maintained. It is.

  The Shore D hardness of the metal ion neutralized product of the olefin-unsaturated carboxylic acid random copolymer of component (a) must be 60 or more, preferably 61 or more, more preferably 62 or more. This component (a) becomes the base resin of the cover material. Therefore, the material hardness of the base resin occupies a large weight in the hardness, durability, and scratch resistance of the ball, so the Shore D hardness is set within the above range. The

  Examples of the metal ion neutralized product of the random copolymer that is the component (a) include Himiran 1605, 1706, AM7317, AM7318, AM7315 (all manufactured by Mitsui DuPont Polychemical Co., Ltd.), Surlyn 7930. , 8150, 8220, 9150 (all manufactured by DuPont).

In the present invention, the unsaturated fatty acid as component (b) includes oleic acid (18 carbon atoms), elaidic acid (trans isomer of oleic acid), erucic acid (22 carbon atoms), linoleic acid (18 carbon atoms). And linolenic acid (carbon number 18) , and one of these can be used alone or in combination of two or more, and oleic acid is particularly preferably used.

  The amount of the component (b) is 5 parts by mass or more, preferably 8 parts by mass or more, and more preferably 10 parts by mass or more with respect to 100 parts by mass of the component (a). If the amount is less than this amount, the hardness of the ionomer resin may not be lowered to a desired hardness. Moreover, as an upper limit, it is 60 mass parts or less with respect to 100 mass parts of (a) component, Preferably it is 50 mass parts or less, More preferably, it is 40 mass parts or less. If this amount is exceeded, it will be difficult to tackle the resin and bleed easily.

  In the present invention, as described above, an unsaturated fatty acid is blended as the component (b), but the blending amount is relatively small as described above, and there is a problem such as molding defects. I think it will not be.

  In addition, the use of unsaturated fatty acids containing one or more double bonds in the molecule is more effective for ionomer resins than saturated fatty acids having no such double bonds (for example, stearic acid (18 carbon atoms)). This is because it has been found that the effect of reducing the hardness is very large.

  The golf ball material of the present invention comprises a basic inorganic metal compound capable of neutralizing the acid groups in the components (a) and (b) as component (c), and is an ionomer resin. The unneutralized carboxyl group in the inside and the carboxyl group in the component (b) are neutralized to form a metal salt. Thereby, the cross-linking becomes strong, the resilience performance and the molding performance can be freely adjusted, and the scratch resistance is considered to be improved.

Here, examples of the metal ions used for the basic inorganic metal compound include Li ⁺ , Na ⁺ , K ⁺ , Ca ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , Al ⁺⁺⁺ , Ni ⁺ , and Fe ^++. , Fe ⁺⁺⁺ , Cu ⁺⁺ , Mn ⁺⁺ , Sn ⁺⁺ , Pb ⁺⁺ , Co ^{++ and the} like. Examples of inorganic metal compounds include basic inorganic fillers containing these metal ions, specifically Examples include magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, sodium hydroxide, sodium carbonate, calcium oxide, calcium hydroxide, lithium hydroxide, lithium carbonate, etc., and particularly reactive with ionomer resins. High calcium hydroxide can be preferably used.

  The amount of the component (c) is 1 part by mass or more, preferably 1.2 parts by mass or more, and more preferably 1.5 parts by mass or more with respect to 100 parts by mass of the component (a). If the amount is less than this, the degree of neutralization is insufficient, and sufficient resilience may not be obtained. Moreover, as an upper limit, it is 10 mass parts or less with respect to 100 mass parts of (a) component, Preferably it is 7 mass parts or less, More preferably, it is 6 mass parts or less.

  In the mixture of the components (a) to (c), other materials may be appropriately blended, but in any case, the melt mass flow rate (JIS-K7210 (test temperature 190 ° C., test load 21 N) as a mixture) (Measured at 2.16 kgf))) is preferably 2.0 g / 10 min or more, more preferably 2.5 g / 10 min or more, and the upper limit is preferably 6 g / 10 min or less, more preferably 5 g / min. It is recommended that it be 10 min or less. If the melt mass flow rate of the heated mixture is small, the workability is significantly lowered.

  The mixture can be obtained by preparing various additives as necessary. For example, when used as a cover material, the mixture is further mixed with a pigment, a dispersant, an anti-aging agent, an ultraviolet absorber. Agents, light stabilizers and the like can be added. Further, in the material of the present invention, various non-ionomer thermoplastic elastomers can be blended in addition to the above-mentioned essential components in order to improve the feeling at the time of impact. As such non-ionomer thermoplastic elastomers, Examples thereof include olefin elastomers, styrene elastomers, ester elastomers, urethane elastomers, and the like, and the use of olefin elastomers and styrene elastomers is particularly preferable.

  The mixing method of the mixture is not particularly limited. For example, the heating temperature is 150 to 250 ° C., and the mixer is, for example, an internal mixer such as a kneading type twin screw extruder, Banbury, or kneader. It can be kneaded. In this case, there is no restriction on the method of blending various additives other than the essential components (a) to (c), a method of blending together with the essential components and heating and mixing at the same time, and heating and mixing the essential components in advance. Thereafter, a method of adding an arbitrary additive and further heating and mixing can be exemplified. In particular, when a co-rotating twin screw extruder is used, the unsaturated fatty acid may be injected from each vent port of the twin screw extruder using a plunger pump or the like. The basic inorganic metal compound may be added from any place using a side feed.

  In order to obtain a cover according to the present invention, for example, a single layer or a multilayer core of two or more layers prepared in advance according to the type of ball is placed in a mold, the mixture is heated, mixed, melted, and injection molded. A method of covering a desired cover around the core can be employed. In this case, the cover can be manufactured with excellent thermal stability, fluidity, and moldability, so that the golf ball finally obtained has high resilience and hit feeling. And good scratch resistance. In addition to the above, the cover is formed by, for example, previously forming a pair of hemispherical half cups with the cover material of the present invention, and wrapping the core with the half cups at 120 to 170 ° C. for 1 to 5 minutes. Alternatively, a pressure molding method or the like can be employed.

  In the present invention, the cover is not limited to one layer, and may be formed in a multilayer structure of two or more layers. For example, when the cover has one layer, the thickness is preferably 0.5 to 3 mm. When the cover has two layers, the outer layer cover has a thickness of 0.5 to 2.0 mm. The thickness is preferably in the range of 0.5 to 2.0 mm. In the case of a multilayer structure, the cover material of the present invention may be used on the inner side of the multilayer structure or the outermost layer cover, but in the present invention, it can be suitably used for the outermost layer. That is, when the cover is formed of two or more layers, the above (a) to (c) are used as the main materials of the outermost layer in order to obtain a good hitting feeling and to further improve the scratch resistance. It is preferred to apply a molded product of the mixture containing the component.

Regarding the hardness of the cover, the Shore D hardness of each layer (cover layer) constituting the cover is in the range of 46 or more and 58 or less.

  In addition, a large number of dimples are formed on the surface of the outermost layer of the cover, and various treatments such as base treatment, stamping, painting, and the like can be performed on the cover, and in particular, the cover material of the present invention is used. When such a surface treatment is applied to the cover, the workability can be improved because the cover surface has good moldability.

  The present invention is a golf ball in which a material obtained by molding the above mixture is used for at least one cover layer, and the type of the golf ball basically has a core and at least one cover layer. If there is no particular limitation, for example, a two-piece or three-piece solid golf ball having a solid core covered with a cover, a solid golf ball such as a multi-piece golf ball having a three-layer structure or more, and a single layer on a wound core Alternatively, it can be used for a wound golf ball covered with a cover having a multilayer structure of two or more layers.

  The golf ball of the present invention can be used in competition and comply with the golf rules, and can be formed with a diameter of 42.67 mm or more and a weight of 45.93 g or less. Further, the golf ball of the present invention can be suitably applied to any competition player regardless of an amateur golfer having a head speed of 30 to 40 m / s or a professional golfer having a head speed of 45 m / s or more.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Examples 1-6, Comparative Examples 1-4]
A solid core having a diameter of 35.3 mm, a weight of 27.1 g, and a deflection deformation amount of 4.0 mm under a load of 100 kg was prepared using a core material mainly composed of polybutadiene shown in Table 1 below. The value of the deformation amount is a value obtained by measuring the deformation amount from when the initial load 98N (10 kgf) is applied to the core to when the final load 1275N (130 kgf) is applied.

The details of the above blending are as follows.
・ Polybutadiene (1): Trade name “BR01” (manufactured by JSR)
-Polybutadiene (2): Trade name “BR51 (BR730 extrudability improvement grade)”
(Manufactured by JSR)
・ Peroxide (1): Dicumyl peroxide, trade name “Park Mill D” (manufactured by NOF Corporation)
Peroxide (2): 1,1 bis (t-butylperoxy) 3,3,5-trimethylcyclohexane
Xan, trade name "Perhexa 3M-40" (manufactured by NOF Corporation)
・ Anti-aging agent: Trade name “NOCRACK NS-6” (manufactured by Ouchi Shinsei Chemical Co., Ltd.)

  Next, the intermediate layer material having the composition shown in Table 2 was injected into the mold provided with the solid core so as to have a thickness of 1.65 mm. Next, the cover material was mixed at 200 ° C. by a co-rotating twin screw extruder (screw diameter 32 mm, L / D = 32, motor capacity 7.5 kw, with vacuum vent), and the mixture was surrounded by the intermediate layer material The three-piece solid golf ball having a diameter of 42.7 mm was manufactured by injecting the core into the mold provided with the core and injection molding so that the cover thickness was 2.05 mm. Note that the surface of the golf ball of any example was painted with a non-yellowing urethane resin-based paint. Various characteristics (initial speed, feel, scratch resistance, etc.) of the golf balls of each example were evaluated as follows. The results are also shown in Table 2.

The details of the above blending are as follows.
(I) Product name “Hytrel 4047”
Thermoplastic polyetherester elastomer (Shore D hardness 40), manufactured by Toray DuPont
(II) Product name “High Milan 1706”
Made by Mitsui DuPont Polychemical Co., Ltd., Zn ion neutralization, ethylene-methacrylic acid copolymer ionomer resin (Shore D hardness 64)
(III) Product name “High Milan 1605”
Made by Mitsui DuPont Polychemical Co., Ltd., Na ion neutralized, ethylene-methacrylic acid copolymer ionomer resin (Shore D hardness 65)
(IV) Product name “Hi Milan 1601”
Made by Mitsui DuPont Polychemical Co., Ltd., Na ion neutralized, ethylene-methacrylic acid copolymer ionomer resin (Shore D hardness 59)
(V) Product name “High Milan 1557”
Made by Mitsui DuPont Polychemical Co., Ltd., Zn ion neutralized, ethylene-methacrylic acid copolymer ionomer resin (Shore D hardness 59)
(VI) Oleic acid trade name “NAA-300” (manufactured by NOF Corporation)
(VII) Magnesium stearate trade name “Nissan Magnesium Stearate” (manufactured by NOF Corporation)
(VIII) Titanium oxide Product name "Taipeke R550" (Ishihara Sangyo Co., Ltd.)
(IX) Blue pigment Trade name “Ultramarine Blue EP-62” (manufactured by HOLLIDAY PIGMENTS)
(X) Calcium hydroxide Product name “CLS-B” (manufactured by Shiroishi Calcium Co., Ltd.)

[Evaluation of physical properties of cover materials]
Melt mass flow rate Melt mass flow rate (or melt index) of a material measured according to JIS-K7210 (test temperature 190 ° C., test load 21 N (2.16 kgf)).

The material hardness of the intermediate layer and the cover resin represents the Shore D hardness measured according to ASTM D-2240.

[Evaluation of various physical properties of the ball]
Ball deflection (mm)
The amount of deformation (mm) from when the initial load of 98 N (10 kgf) was applied to the golf ball to when the final load of 1275 N (130 kgf) was applied was determined.

Initial ball speed (m / s)
The initial velocity (m / s) when measured according to the R & A (USGA) rule was measured using an initial velocity meter of the same type as the golf ball official recognition organization R & A (USGA).

Feeling (feeling)
A golf club (W # 1) was used, and sensory evaluation was performed according to the following criteria by 10 amateur golfers having a head speed of 35 to 40 m / s.
○: 7 or more out of 10 people feel good.
Δ: 5 or 6 people feel good.
X: Less than 4 out of 10 people feel good.

Scratch resistant Bridgestone's product name "X-WEDGE 03" (Loft angle 52 °) non-plated one is set on the striking robot, the face is opened about 30 ° from the square, and the head speed (HS) is 33 m / s Blow. The golf players within 3 HDCP10s visually observed the surface condition, and expressed by the average score based on the following criteria.
5 points: The ball surface does not change at all or the club face trace remains slightly. 4 points: The club face trace remains considerably, but there is no fuzz on the cover surface.
3 points: The surface is fuzzy and the chicken is conspicuous.
2 points: The surface is fuzzy and there are cracks.
1 point: Dimples are scraped off.

  From the results shown in Table 1, the golf ball of this example is excellent in ball resilience, scratch resistance and hit feeling, whereas the golf ball of a comparative example has poor hit feeling or scratch resistance. It turns out that it has not improved.

Claims (2)

In a golf ball having a core and a cover of one or more layers, an olefin-unsaturated carboxylic acid random in which the outermost layer constituting the cover has the following components (a) to (c) (a) a Shore D hardness of 60 or more 100 parts by mass of copolymer neutralized metal ion,
(B) 5-60 parts by mass of at least one unsaturated fatty acid selected from the group consisting of oleic acid, elaidic acid, erucic acid, linoleic acid and linolenic acid,
And (c) a basic inorganic metal compound capable of neutralizing acid groups in the components (a) and (b)
By forming a mixture having a melt mass flow rate of 1 to 10 parts by mass as an essential component of 2.0 g / 10 min or more, the Shore D hardness of the component (a) decreases in the range of 7 to 18 and Shore D A golf ball formed of a material having a hardness of 46 to 58.   The golf ball according to claim 1, wherein the basic inorganic metal compound as the component (c) is calcium hydroxide.