GOLF BALL

Abstract

In a golf ball having a core and a cover of one or a plurality of layers that encases the core, the core or at least one layer of the cover is formed of a resin composition which contains from 5 to 250 parts by weight of a mechanoluminescent material that receives mechanical energy and luminesces per 100 parts by weight of a base material which is a rubber material or a resin material. This golf ball has an excellent visibility in that, even under dark conditions, the ball impact site can be clearly confirmed visually at the time of impact. Moreover, the ball is able to maintain a good scuff resistance.

Claims

1. A golf ball comprising a core and a cover of one or a plurality of layers that encases the core, wherein the core or at least one layer of the cover is formed of a resin composition which contains from 5 to 250 parts by weight of a mechanoluminescent material that receives mechanical energy and luminesces per 100 parts by weight of a base material which is a rubber material or a resin material.

2. The golf ball of claim 1, wherein the mechanoluminescent material is a material comprising strontium aluminate crystals doped with primarily at least one type of rare-earth ion.

3. The golf ball of claim 1, wherein the mechanoluminescent material-containing resin material is an ionomer resin.

4. The golf ball of claim 1, wherein an outermost layer of the cover is formed of a mechanoluminescent material-containing resin composition, the content of the mechanoluminescent material being from 15 to 100 parts by weight per 100 parts by weight of the resin material.

5. The golf ball of claim 1 wherein the cover has a plurality of layers, and an inner cover layer adjoining an outermost layer of the cover is formed of a mechanoluminescent material-containing resin composition.

6. The golf ball of claim 5, wherein the content of the mechanoluminescent material included in the inner cover layer is from 20 to 250 parts by weight per 100 parts by weight of the resin material.

Description

EXAMPLE

[0046] Working Examples and Comparative Examples are provided below to illustrate the invention, and are not intended to limit the scope thereof.

Working Examples 1 to 7, Comparative Examples 1 to 3

[0047] Solid cores were produced by using the rubber composition shown in Table 1 below, which composition was common to all the Examples, and vulcanizing for 15 minutes at 155° C.

TABLE-US-00001 TABLE 1 Rubber composition (pbw) A Polybutadiene 100 Zinc oxide 4.00 Barium sulfate 1.8 Calcium carbonate 22.0 Antioxidant 0.1 Zinc acrylate 26 Organic Peroxide (1) 0.6 Organic Peroxide (2) 0.6

[0048] Details on the above solid core materials are given below. [0049] Polybutadiene: Available under the trade name “BR01” from JSR Corporation [0050] Zinc oxide: Available from Sakai Chemical Co., Ltd. [0051] Barium sulfate: Available from Sakai Chemical Co., Ltd. [0052] Calcium carbonate: Available from Shiraishi Calcium Kaisha, Ltd. [0053] Antioxidant: Mono-(or di- or tri-)(α-methylbenzyl)phenol, available under the trade name “Nocrac SP-N” from Ouchi Shinko Chemical Industry Co., Ltd. [0054] Zinc acrylate: Available from Nippon Shokubai Co., Ltd. [0055] Organic Peroxide (1): Dicumyl peroxide, available under the trade name “Percumyl D” from NOF Corporation [0056] Organic Peroxide (2): A mixture of 1,1-di(tert-butylperoxy)cyclohexane and silica, available under the trade name “Perhexa C-40” from NOF Corporation

[0057] Next, in Working Examples 1 to 6 and Comparative Examples 1 to 3. cover materials formulated as shown in Table 2 below were mixed in a kneading-type twin-screw extruder, giving pelletized cover materials, following which these cover materials were injected into a mold in which the solid core had been placed, thereby producing two-piece solid golf balls. In Working Example 7 alone, separate cover materials for the inner cover layer and the outer cover layer were successively injection-molded over the core, thus producing a three-piece solid golf ball. Dimples common to all the Examples were formed on the surface of the cover at this time.

TABLE-US-00002 TABLE 2 Resin material ingredients (pbw) a b c d e f g h i j Himilan 50 50 50 50 50 50 50 50 50 50 1605 Himilan 50 50 50 50 50 50 50 50 50 50 1706 Mechanoluminescent 5 10 20 40 100 150 230 0 2 70 material Total 105 110 120 140 200 250 330 100 102 170 Shore D 65.7 66.3 67.2 68.1 71.8 75.1 79.0 64.4 65.3 69.5 hardness

[0058] Details on the materials mentioned in Table 2 are given below. [0059] Himilan 1605: A sodium-neutralized ionomer from DuPont-Mitsui Polychemicals Co., Ltd. [0060] Himilan 1706: A zinc-neutralized ionomer from DuPont-Mitsui Polychemicals Co., Ltd. [0061] Mechanoluminescent material: [0062] The mechanoluminescent powder ML-032 (strontium aluminate (SAO) crystals doped primarily with the rare-earth europium) from Sakai Chemical Co., Ltd.

Shore D Hardness of Cover Material

[0063] The cover material (resin composition) was molded into a sheet having a thickness of 2 mm and left to stand for at least two weeks, following which the Shore D hardness was measured in accordance with ASTM D2240-95.

[0064] The surfaces of the golf balls obtained above were coated to a thickness of 16 μm with the coating compositions in Table 3 below, thereby producing golf balls as finished products.

TABLE-US-00003 TABLE 3 Coating formulation (pbw) l m Base resin of clear coat (two-part urethane mixture) 66.7 66.7 Hardener of clear coat (two-part urethane mixture) 33.3 33.3 Mechanoluminescent material 0 100 Total 100.0 200.0 [0065] Base resin: from Asia. Industry Co., Ltd. [0066] Hardener: from Asia Industry Co., Ltd. [0067] Mechanoluminescent material: [0068] Same as mechanoluminescent material used in cover material

[0069] The ball diameter, deflection, luminescent state and scuff resistance for each of the golf balls obtained above were measured or evaluated by the following methods. The results are shown in Table 4.

Golf Ball Diameter

[0070] The diameters at five random dimple-free areas on the surface of a ball were measured at a temperature of 23.9+1° C. and, using the average of these measurements as the measured value for a single ball, the average diameter for five measured balls was determined.

Deflection of Golf Ball

[0071] The golf ball was placed on a hard plate and the amount of deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) was measured. The amount of deflection here refers in each case to the measured value obtained after holding the ball isothermally at 23.9° C.

Luminescent State

[0072] Three balls of each type were hit with a driver (W#1) at a head speed of 40 m/s, the impact site of each ball was visually observed and rated based on the following 5-point scale, and the average score was calculated for each type of ball.

[0073] 5: Luminescence can be even more clearly confirmed by naked eye.

[0074] 4: Luminescence can be clearly confirmed by naked eve.

[0075] 3: Luminescence can be confirmed by naked eye.

[0076] 2: Slight luminescence can be confirmed by naked eye.

[0077] 1: Confirmation of luminescence by naked eye is difficult.

Scuff Resistance

[0078] The golf balls were held isothermally at 23° C. and five balls of each type were hit at a head speed of 33 m/s using as the club a pitching wedge mounted on a swing robot machine. The damage to the ball from the impact was visually rated based on the following 5-point scale, and the average score was calculated for each type of ball.

[0079] 5: No damage or substantially no damage.

[0080] 4: Damage is apparent but so slight as to be of substantially no concern.

[0081] 3: Surface is slightly frayed.

[0082] 2: Some fraying of surface or loss of dimples.

[0083] 1: Dimples completely obliterated in places.

TABLE-US-00004 TABLE 4 Comparative Working Comp. Working Example Example Ex. Ex. 1 2 3 4 5 6 1 2 7 3 Core Core A A A A A A A A A A composition Diameter (mm) 39.30 39.30 39.30 39.30 39.30 39.30 39.30 39.30 38.55 39.30 Cover Structure 1 1 1 1 1 1 1 1 2 1 layer layer layer layer layer layer layer layer layers layer Inner cover none e none layer material Thickness (mm) 1.1 Outer cover a b c d e f i g h h layer material Thickness (mm) 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.0 1.7 Coating Type 1 1 1 1 1 1 1 1 1 m Product Diameter (mm) 42.67 42.73 42.72 42.72 42.69 42.69 42.70 42.69 42.71 42.69 Deflection (mm) 2.8 2.8 2.7 2.7 2.6 2.5 2.8 2.4 2.7 2.8 Evalution Luminescent 2 2 3 3 4 5 1 5 3 3 State Scuff resistance 5 5 4 4 3 2 3 1 4 1

[0084] Japanese Patent Application No. 2016-123266 is incorporated herein by reference.

[0085] Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.