JP2005224293A - Golf ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf ball which can realize an optimal back spinning amount in response to a golf club. <P>SOLUTION: This golf ball 1 contains a core 2, a cover 3 which covers the core 2, and a metal coating film 4 which is formed on the cover 3, and is constituted in such a manner that the static frictional coefficient of the surface of the golf ball 1 may be 0.4 or higher. In this case, the static frictional coefficient of the surface of the golf ball 1 is preferably to be from 0.4 to 0.8. The thickness of the metal coating film 4 is preferably to be from 1 to 1,000 μm. In addition, the metal coating film 4 is preferably made of aluminum. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a golf ball, and more particularly to a golf ball capable of realizing an optimal backspin amount in accordance with a golf club.

  In general, when hitting with a driver with a small loft angle or a long iron club with a low count, increase the flight distance of the hit ball as much as possible, and when hitting with a sand wedge or a short iron club with a high count, the distance that the ball rolls after falling It is ideal to reduce (hereinafter also referred to as “run”) as much as possible.

  Therefore, when hitting with a driver with a small loft angle or a long iron club with a low count, the backspin amount of the hit ball is suppressed to some extent, and when hitting with a sand wedge or a short iron club with a high count, the backspin amount is increased. It is necessary.

  Conventionally, the backspin amount of such a hit ball greatly depends on the friction coefficient of the face surface of the golf club that the golf ball contacts at the time of impact, and the backspin amount of the hit ball increases as the friction coefficient of the face surface increases. It is considered.

  As described above, golf club techniques for controlling the backspin amount of a hit ball include the following techniques.

  For example, Patent Document 1 discloses a technique for controlling a backspin amount of a hit ball by continuously changing a friction coefficient of a face surface of a golf club with a change in the number of counts.

  Further, in Patent Document 2, a plurality of depressions (punch marks) are formed on the face surface of a golf club, and the shape and depth of the punch marks are changed in accordance with the change in the number of counts, thereby increasing the backspin amount. Techniques for adjusting are disclosed.

  Patent Document 3 discloses a technique for forming a groove on the face surface of a golf club and adjusting the backspin amount by changing the width, depth, etc. of the groove as the number of counts changes. Yes.

  Further, Patent Document 4 discloses a technique for adjusting the backspin amount of the hit ball by decreasing the angle formed by the hitting surface of the golf club and the inclined surface of the groove as the number of golf balls increases.

  These technologies are designed to reduce the friction coefficient of the face surface of the golf club when reducing the backspin amount of the hit ball, and increasing the coefficient of friction of the face surface when increasing the backspin amount. This adjusts the amount of backspin.

  However, in these techniques, the backspin amount certainly increases when hitting with a high iron golf club such as a short iron, but a driver with a loft angle of less than 40 °, Nos. 3, 5, and 7 It was found that when the friction coefficient of the face surface of the number iron club was reduced, the backspin amount of the hit ball increased unexpectedly (see paragraph [0005] of Patent Document 5).

  Thus, since the approach from the golf club side is not sufficient for adjusting the backspin amount of the hit ball, the approach from the golf ball side is also necessary.

  As an approach from the golf ball side, for example, there is a method of making the golf ball cover soft and thin. According to this method, it is possible to increase the backspin amount of the hit ball when hitting with a high-counter iron club, and not to reduce the hit ball speed when hitting with a driver and a low-counter iron club. .

However, even in this method, the backspin amount of the hit ball in the driver or the high-count iron club cannot be reduced, and the backspin amount cannot be adjusted sufficiently.
JP-A-61-272067 JP-A-2-228980 Japanese Patent Laid-Open No. 2-228981 JP 9-192274 A JP 2000-254256 A

  An object of the present invention is to provide a golf ball capable of realizing an optimal backspin amount in accordance with a golf club.

  The present invention is a golf ball that includes a core, a cover that covers the core, and a metal film formed on the cover, and the golf ball surface has a static friction coefficient of 0.4 or more. .

  Here, in the golf ball of the present invention, the coefficient of static friction is preferably 0.4 or more and 0.8 or less.

  In the golf ball of the present invention, the metal film preferably has a thickness of 1 μm or more and 1000 μm or less.

  Furthermore, in the golf ball of the present invention, the metal film is preferably made of aluminum.

  In the present invention, it is possible to provide a golf ball capable of realizing an optimal backspin amount in accordance with a golf club. Therefore, in the present invention, when hitting with a driver with a small loft angle or a low count iron club, the backspin amount is reduced to increase the flight distance of the hit ball, and the hit with a sand wedge or a high count iron club In this case, it is possible to increase the backspin amount and decrease the run.

  Embodiments of the present invention will be described below. In the drawings of the present application, the same reference numerals represent the same or corresponding parts.

(Golf ball)
FIG. 1 shows a schematic cross-sectional view of a preferred example of the golf ball of the present invention. The golf ball 1 of the present invention includes a core 2, a cover 3 that covers the core 2, and a metal coating 4 that is formed on the cover 3.

  The golf ball of the present invention is not limited to this, and may be a multi-layer golf ball having three or more pieces, or a wound golf ball having a wound core. Therefore, there may be one or more intermediate layers between the core 2 and the cover 3. Further, a polyurethane-based paint layer may be provided between the cover 3 and the metal coating 4, but in terms of bringing the metal coating 4 into close contact with the cover 3, it is preferable that there is no polyurethane-based paint layer.

  Here, the static friction coefficient of the surface of the golf ball of the present invention is 0.4 or more. By setting the static friction coefficient of the surface of the golf ball to 0.4 or more, the driver or the face surface of the Nos. 3, 5, and 7 iron clubs having a loft angle of less than 40 ° compared to the conventional golf ball. Even when the friction coefficient is reduced, the backspin amount of the hit ball is reduced and the launch angle is also increased. Further, in a high-count iron golf club such as a short iron, the backspin amount of the hit ball increases as the friction coefficient of the face surface increases as in the conventional case.

  Further, the coefficient of static friction on the surface of the golf ball of the present invention is preferably 0.45 or more, and more preferably 0.5 or more. By setting the static friction coefficient of the surface of the golf ball to 0.45 or more, particularly 0.5 or more, the tendency that the backspin amount of the hit ball can be controlled to an optimum amount corresponding to the golf club is increased.

  In addition, the coefficient of static friction on the surface of the golf ball of the present invention is preferably 0.8 or less, more preferably 0.75 or less, and even more preferably 0.7 or less. When the static friction coefficient on the surface of the golf ball is larger than 0.8, the backspin tends to be less likely to be applied to the hit ball when hit with a high-count iron club. This tendency becomes smaller as the static friction coefficient of the golf ball surface becomes 0.75 or less and 0.7 or less.

  Further, the coefficient of static friction on the surface of the golf ball of the present invention is preferably 0.4 or more and 0.8 or less, and more preferably 0.5 or more and 0.7 or less. When the static friction coefficient of the surface of the golf ball is 0.4 or more and 0.8 or less, particularly 0.5 or more and 0.7 or less, the backspin amount of the hit ball is an optimum amount corresponding to the golf club as described above. The tendency to be able to control is particularly increased.

  The schematic side view of FIG. 2 shows an example of a measuring apparatus used for measuring the static friction coefficient in the present invention. The measuring device includes a flat plate 5 attached to a compressor, a metal face plate 6, and a carriage 7 having a load cell 8.

  Then, the golf ball 1 is fixed to the carriage 7 with almost half exposed, and the face plate 6 is fixed to the flat plate 5 so that the surface of the golf ball 1 and the surface of the face plate 6 are brought into contact with each other. Next, with the vertical load of 400 kgf applied to the flat plate 5, the carriage 7 is moved in the horizontal direction at a speed of 50 mm / min, and the horizontal load at that time is measured by the load cell 8.

  As shown in FIG. 3, the measured lateral load has a wavy line shape, and a value obtained by dividing the maximum static friction force, which is the maximum height of the wavy line, by the vertical load (400 kgf) is calculated as the static friction coefficient.

The contact area between the golf ball 1 and the face plate 6 is approximately 300 mm ² . A specific example of such a measuring apparatus is, for example, UNIVERSAL TESTING MACHINE RH-30 manufactured by Shimadzu Corporation.

(core)
In the present invention, a thread-wound core, a single layer or a multi-layer core is used as the core, and can be employed for either a thread-wound ball or a solid ball. And the specific gravity of a core employ | adopts the range of 1.05-1.25 normally, and is suitably adjusted with the compounding quantity of a filler.

  The core is composed of a crosslinked product of a rubber composition, and it is preferable to use a high-cis polybutadiene rubber having a cis-1,4-structure as the rubber component of the rubber composition. However, in addition to high-cis polybutadiene rubber, natural rubber, styrene butadiene rubber, isoprene rubber, chloroprene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile rubber or the like is mixed at 40% by mass or less in the rubber component. It is also possible to use what has been done.

  As a crosslinking agent for the rubber composition, an α, β-ethylenically unsaturated compound is produced by reacting an α, β-ethylenically unsaturated carboxylic acid such as acrylic acid or methacrylic acid with a metal oxide during the preparation of the rubber composition. Metal salts of carboxylic acids, metal salts of α, β-ethylenically unsaturated carboxylic acids such as zinc acrylate or zinc methacrylate, and polyfunctional monomers such as N, N′-phenylbismaleimide and sulfur Can be blended. In particular, a metal salt of α, β-ethylenically unsaturated carboxylic acid is preferably used as the crosslinking agent.

  When a metal salt of an α, β-ethylenically unsaturated carboxylic acid is used as the crosslinking agent, the blending amount is preferably 20 to 40 parts by mass with respect to 100 parts by mass of the rubber component. In addition, when α, β-ethylenically unsaturated carboxylic acid and metal oxide are reacted during the preparation of the rubber composition to form a metal salt of α, β-ethylenically unsaturated carboxylic acid, the blending amount thereof Is 15 to 30 parts by mass of α, β-ethylenically unsaturated carboxylic acid with respect to 100 parts by mass of the rubber component, and 15 to 35 with metal oxide such as zinc oxide based on α, β-ethylenically unsaturated carboxylic acid. It is preferable to mix by mass%.

  Moreover, 1 type, or 2 or more types of inorganic powders, such as barium sulfate, a calcium carbonate, clay, or a zinc oxide, can be mix | blended with a rubber composition as a filler, for example. The blending amount of the filler is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the rubber component. Moreover, you may mix | blend a softener, an antiaging agent, etc. suitably for the purpose of workability | operativity improvement or hardness adjustment.

  The rubber composition may contain an organic peroxide such as dicumyl peroxide and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane as a crosslinking initiator. . It is preferable that the compounding quantity of a crosslinking initiator is 0.1-5 mass parts with respect to 100 mass parts of rubber components, especially 0.3-3 mass parts.

  Moreover, an organic sulfur compound can also be mix | blended with a rubber composition. Organic sulfur compounds include, for example, tetramethyltyramium disulfide, tetrabutyltyramium disulfide, dipentamethylenetyramium tetrasulfide and other tyramiums, morpholine disulfide, alkylphenol disulfide, diphenyl monosulfide, diphenyl disulfide, diphenyl polysulfide, diphenyl Sulfides such as pentachlorodiphenyl disulfide, morpholine disulfide, and dixylyl disulfide, thiophenols such as pentachlorothiophenol, 4-t-butylthiophenol, 2-benzamidothiophenol, thiocarboxylic acids such as thiobenzoic acid, or dithio Acid salts and the like can be used. The amount of the organic sulfur compound is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and 0.2 to 2 parts by mass with respect to 100 parts by mass of the rubber component. More preferably.

  And after adding an additive, such as the said crosslinking agent, to the said rubber component, a core mixes using a roll, a kneader, or a banbury etc., Then, it inject | pours into a metal mold | die, Preferably it is 130-175 degreeC for 5 to 40 minutes Manufactured by vulcanization. Here, the vulcanization can be performed twice or more.

(cover)
In the present invention, the base resin for the cover is an ionomer resin, for example, a copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and at least a part of the carboxyl group. Binary copolymers obtained by neutralization with metal ions can be used. And a terpolymer of an α-olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α, β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms, wherein at least one of the carboxyl groups. An ionomer resin or the like obtained by neutralizing a part with metal ions can also be used.

  As said alpha olefin, ethylene, propylene, 1-butene, 1-pentene etc. can be used, for example, It is preferable to use especially ethylene. As the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid or crotonic acid can be used, and acrylic acid and methacrylic acid are particularly preferable. . As the α, β-unsaturated carboxylic acid ester, for example, methyl ester such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, ethyl ester, propyl ester, n-butyl ester or isobutyl ester can be used. In particular, it is preferable to use acrylic acid ester or methacrylic acid ester.

  Binary copolymer of the above α-olefin and α, β-unsaturated carboxylic acid or terpolymer of α-olefin, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester As a metal ion that neutralizes at least a part of the carboxyl group therein, for example, sodium ion, lithium ion, zinc ion, magnesium ion or potassium ion can be used.

  Specific examples of the above ionomer resins are exemplified by trade names: High Milan 1555 (Na), High Milan 1557 (Zn), High Milan 1605 (Na), High Milan 1706 (Zn), High Milan 1707 (Na ), High Milan AM7318 (Na), High Milan AM7315 (Zn), High Milan AM7317 (Zn), High Milan AM7311 (Mg), High Milan MK7320 (K), High Milan 1856 (Na), High Milan 1855 (Zn) or High Milan AM7316 (Zn), etc. There is.

  Furthermore, as ionomer resins commercially available from DuPont, Surlyn 8945 (Na), Surlyn 8940 (Na), Surlyn 9910 (Zn), Surlyn 9945 (Zn), Surlyn 7930 (Li), Surlyn 7940 (Li), Surlyn AD8265 (Na) or Surlyn AD8269 (Na).

  Examples of the ionomer resin commercially available from Exxon Chemical Co. include Iotech 7010 (Zn) and Iotech 8000 (Na). In addition, Na, Zn, K, Li, and Mg described in parentheses under the trade name of the ionomer resin indicate metal species of these neutralized metal ions. In the present invention, the ionomer resin used for the base resin of the cover may be a mixture of two or more of those exemplified above, or an ionomer resin neutralized with the monovalent metal ion exemplified above and a divalent resin. Two or more ionomer resins neutralized with the above metal ions may be mixed and used.

  In addition, as the base resin for the cover used in the present invention, one or more thermoplastic elastomers can be mixed with the above ionomer resin.

  Specific thermoplastic elastomers include, for example, a styrene-butadiene-styrene block copolymer (SBS structure), and a styrene-ethylene-butylene-styrene block copolymer (SEBS structure) obtained by hydrogenating the double bond portion of the butadiene. , Ethylene-isobutylene-styrene block copolymer (SIS structure), styrene-ethylene-propylene-styrene block copolymer (SEPS structure) obtained by hydrogenating the isoprene double bond portion, or a modified one thereof Can do.

  In the present invention, additives such as a colorant, an anti-aging agent, a plasticizer, a dispersant, or an ultraviolet absorber can be appropriately blended with the base resin of the cover as necessary.

  In order to cover the core with a cover, first, a base resin of the cover and, if necessary, an additive such as a pigment, a dispersant, an anti-aging agent, an ultraviolet absorber or a light stabilizer are mixed, and a twin-screw extruder Then, using a Banbury mixer or a kneader, the mixture is heated and mixed at 150 to 250 ° C. for 0.5 to 15 minutes to prepare a cover composition.

  The method of covering the core with the cover is not particularly limited, and the core can be coated by a conventionally known method. For example, a method in which the cover composition is molded into a half-shell half shell, the core is encapsulated in a pair of half shells to form a sphere, and then heat-molded at 130 to 170 ° C. for 1 to 15 minutes, or the core For example, a method of directly injection-molding the cover composition on the surface can be employed.

(Metal coating)
A metal film is formed on the cover. A polyurethane-based paint layer is formed on a golf ball cover that has been used in the past, but the coefficient of static friction with the face surface of the golf club is not large even if the existing base resin of the cover is changed. does not change. Therefore, a metal film is formed on the cover in order to make the static friction coefficient of the golf ball surface 0.4 or more.

  Here, the metal coating is preferably made of aluminum, and can be formed on the cover using, for example, a vacuum deposition method, a CVD method, a sputtering method, an ion plating method, or the like.

  The thickness of the metal coating is preferably 1 μm or more, more preferably 5 μm or more, and further preferably 8 μm or more. When the thickness of the metal film is less than 1 μm, the metal film tends to be peeled off from the cover, and the optimum backspin amount tends to be difficult to obtain depending on the golf club. Such a tendency becomes smaller as the thickness of the metal coating becomes 5 μm or more and 8 μm or more.

  Further, the thickness of the metal coating is preferably 1000 μm or less, more preferably 800 μm or less, and further preferably 500 μm or less. When the thickness of the metal coating is greater than 1000 μm, the golf ball is not easily deformed, and conversely, the backspin amount of the hit ball in the driver or the low-count iron club tends to increase. Such a tendency becomes smaller as the thickness of the metal coating becomes 800 μm or less and 500 μm or less.

  In addition, when the thickness of the metal film is 5 μm or more and 800 μm or less, particularly when the thickness is 8 μm or more and 500 μm or less, the tendency to obtain an optimal backspin amount depending on the golf club is further increased.

  Examples of the present invention will be described below. However, the present invention is not limited to these examples.

i) Preparation of core A rubber composition containing the core shown in Table 1 was kneaded to prepare a plug, which was set in a mold and vulcanized for the first time (at 140 ° C. for 28 minutes). A third vulcanization (at 165 ° C. for 80 minutes) was performed to produce a 39.9 mm diameter core.

ii) Production of cover The base resin having the composition shown in Table 1 was extruded with a twin screw extruder having a cylinder temperature of 180 ° C. The base resin was heated to 190 to 205 ° C. at the die position of the twin screw extruder. Extrusion conditions are as follows.

Screw diameter: 45mm
Screw rotation speed: 200rpm
Screw L / D: 35
Using this base resin, hemispherical half-shells are injection molded, and the two cores are used to wrap the core, and press hot compression molding is performed at 150 ° C. in a mold, and the finish has a diameter of 42.7 mm. A ball was made.

iii) Formation of metal coating In Examples 1 to 3, the finish balls obtained as described above were set in a vacuum deposition apparatus, and aluminum was deposited on the surface of the cover with the thickness shown in Table 1 to form a metal coating. Forming a golf ball.

  In Comparative Example 1, a golf ball was completed by forming a polyurethane-based paint layer on the surface of the cover as in the past.

iv) Measurement of Static Friction Coefficient The static friction coefficients of the golf balls of Examples 1 to 3 and Comparative Example 1 obtained as described above were measured using UNIVERSAL TESTING MACHINE RH-30 manufactured by Shimadzu Corporation.

  Here, the material of the face plate in contact with the surface of the golf ball was a titanium alloy, and the surface roughness of the face plate was 10 μm in terms of 10-point average roughness. The ten-point average roughness of the surface of the face plate was measured in accordance with “Definition and display of ten-point average roughness (Rz)” in item 5 of JIS B0601, and here, the surface shape analysis device SAS- It was measured using 2010 (manufactured by Tokyo Seimitsu Co., Ltd.).

v) Evaluation The golf clubs of Examples 1 to 3 and Comparative Example 1 were set with a titanium wood No. 1 wood club (W # 1; XXIO, manufactured by Sumitomo Rubber Industries) on a swing robot manufactured by True Temper. Hit 12 balls each.

  And the distance (yards) from the hit | damage point of a golf ball to a stop point was measured. Further, the backspin amount (rpm) was measured by taking continuous photographs of the hit golf ball. Then, the average value of the flight distance and the backspin amount was calculated. The average value is shown in Table 1.

  In the same manner as above, a titanium No. 5 iron club (I # 5; XXIO manufactured by Sumitomo Rubber Industries) with a head speed of 38.5 m / s and a sand wedge (SW; Sumitomo Rubber Industries, Ltd.) with a head speed of 21 m / s. The flying distance and backspin amount of the hit ball when the golf ball was hit with XXIO were measured, and the average value thereof was calculated. The average value is shown in Table 1.

(Note 1) High-cis polybutadiene rubber manufactured by JSR (Note 2) Cross-linking agent manufactured by Sanshin Chemical Industry Co., Ltd. (Note 3) Barium sulfate manufactured by Sakai Chemical Industry Co., Ltd. (Note 4) Dicumyl peroxide manufactured by Nippon Oil & Fats Co., Ltd. (Note 5) Diphenyl disulfide manufactured by Sumitomo Seika Co., Ltd. (Note 6) Sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui DuPont (Note 7) Zinc ion neutralized ethylene-methacrylic manufactured by Mitsui DuPont Acid Copolymer Ionomer Resin As shown in Table 1, in Examples 1 to 3, the backspin amount of the hit ball in W # 1 and I # 5 decreased and the flight distance increased in comparison with Comparative Example 1. . Also, the backspin amount of the hit ball with SW increased.

  Further, in Example 1 in which the static friction coefficient is 0.7, the backspin amount of the hit ball at W # 1 and I # 5 is reduced compared to Example 2 in which the static friction coefficient is 0.5. Along with this, the flying distance increased, and the backspin amount of the hit ball with SW also increased.

  Further, in Example 3 in which the thickness of the metal coating was increased as compared with Example 1, the backspin amount of the hit ball at W # 1 and I # 5 was further reduced and the flight distance was increased. The backspin amount of the hit ball decreased.

  In the present invention, an optimal backspin amount can be realized according to the golf club, and therefore the present invention is suitably used in the field of golf balls.

1 is a schematic cross-sectional view of a preferred example of a golf ball of the present invention. It is a typical side view of an example of the measuring apparatus used in order to measure a static friction coefficient in this invention. It is the figure which showed the relationship between the lateral load measured in this invention, and time.

Explanation of symbols

  1 golf ball, 2 core, 3 cover, 4 metal coating, 5 plane plate, 6 face plate, 7 cart, 8 load cell.

Claims (4)

  A golf ball comprising a core, a cover that covers the core, and a metal film formed on the cover, wherein the static friction coefficient of the golf ball surface is 0.4 or more. ,Golf ball.   2. The golf ball according to claim 1, wherein the static friction coefficient is 0.4 or more and 0.8 or less.   The golf ball according to claim 1, wherein a thickness of the metal coating is 1 μm or more and 1000 μm or less.   The golf ball according to claim 1, wherein the metal coating is made of aluminum.

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