JP4514302B2 - Golf ball - Google Patents

Description

【００６４】
注１）サーリン９９４５：亜鉛イオン中和エチレン−メタクリル酸共重合体系アイオノマー樹脂、ＭＩ＝５．２
注２）サーリン８９４５：ナトリウムイオン中和エチレン−メタクリル酸共重合体系アイオノマー樹脂、ＭＩ＝４．８
注３）ＨＧ２５２：クラレ社製の熱可塑性エラストマー（ＳＥＰＳ）
注４）ＴＰ３０１：クラレ社製のトランスポリイソプレンゴム
注５）ＬＡ１０６０：宇部興産社製のナイロン短繊維補強天然ゴム
天然ゴム／低密度ポリエチレン／ナイロン６短繊維＝１００／７５／８７（重量比率）：有機短繊維の直径；０．２μｍ 括弧内は有機短繊維の配合量を示す。
注６）石原産業社製の酸化チタンＡ２２０
注７）堺化学社製の硫酸バリウムＢＭＨ
注８）比較例６、７には硫黄が２重量部、加硫促進剤（大内新興化学社製、ノクセラーＭ（メルカプトベンゾチアゾール）が１重量部配合されている。
【００６５】
表１に実施例１〜実施例３、および比較例１〜比較例７のゴルフボールの測定結果を示す。
【００６６】
比較例１〜比較例６は、熱可塑性エラストマー等のポリマー成分に有機短繊維を配合しないカバー組成物で（２５Ｂ−Ａ）の値が９５０〜１１９０から外れており、スピン性能または耐カット性のいずれかが劣っている。
【００６７】
比較例７はポリマー成分としてアイオノマー樹脂等の熱可塑性樹脂以外のものに有機短繊維を配合したカバー組成物を用いており、耐カット性が劣っている。
【００６８】
実施例１〜実施例３は有機短繊維補強ゴムを配合したカバー組成物で（２５Ｂ−Ａ）の値、Ａの値がいずれも所定の範囲に設定されているため、反発性能、耐カット性およびスピン性能が総合的に優れている。
【００６９】
今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【００７０】
【発明の効果】
本発明のゴルフボールは、カバー組成物のポリマー成分に熱可塑性エラストマーおよび／または熱可塑性樹脂をポリマー成分として用い、これに有機短繊維を所定量配合することにより曲げ剛性率とショアＤ硬度を所定の関係を満たすように設定したため、反発性能を維持しながら、ラフからのアイアンによる打球時にスピン量がかかりやすく、さらに耐カット性に優れたゴルフボールが得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a golf ball having good spin characteristics, that is, a spin amount that is easily controlled when hit with an iron club while maintaining resilience performance and cut resistance.
[0002]
[Prior art]
In general, a golf ball in which a thread wound layer is formed in a liquid center and a balata cover is coated thereon has been widely used by advanced golfers and professional golfers because of its excellent shot feeling and controllability. However, since the structure of such a golf ball has a complicated manufacturing process and is inferior in cut resistance, various soft cover materials that replace balata covers have been proposed recently.
[0003]
For example, Japanese Patent Laid-Open No. 10-179802 discloses an ionomer resin and a styrene-butadiene-styrene block copolymer having a polybutadiene block containing an epoxy group or a polyisoprene block containing an epoxy group as a cover base resin. A two-component heating mixture of styrene-isoprene-styrene block copolymer is used, the bending rigidity of the cover composition is 50 to 300 MPa, and the Shore D hardness is 40 to 60. A golf ball is proposed. This technique is intended to improve the feel at impact, spin performance, and flight performance, but there is room for improvement in cut resistance.
[0004]
Japanese Patent Application Laid-Open No. 9-173504 discloses that a hit feeling is improved and a spin amount with a short iron is increased by using a solid rubber center containing an oily substance and a soft cover material. However, since oil-resistant rubber and ionomer resin with high hardness are used outside the solid rubber center, there is still room for improvement in resilience performance and feel at impact.
[0005]
Japanese Patent Application Laid-Open No. 10-137365 discloses a technique intended to improve resilience, durability and cut resistance by combining a cover material with a thermoplastic resin or thermoplastic elastomer as a main material and a fibrous aluminum borate whisker. Has been proposed. However, this technique reduces the resilience performance of the cover material by blending the fibrous aluminum borate whisker.
[0006]
[Problems to be solved by the invention]
According to the present invention, in order to simultaneously improve the spin performance as well as the cut resistance and the resilience performance, it is necessary to use a resin or elastomer composition having a high flexural rigidity and a low Shore D hardness for the cover material. Based on knowledge.
[0007]
In the resin composition used as a cover material other than the conventional balata, the bending rigidity and the Shore D hardness are substantially correlated, and the Shore D hardness tends to increase as the bending rigidity increases. Therefore, it has been demanded to develop a material having a large flexural rigidity and a low Shore D hardness.
[0008]
In the present invention, for example, by using a resin and / or elastomer reinforced with organic short fibers, a material whose bending rigidity (strength in the bending direction) increases but Shore D hardness (strength in the compression direction) does not change so much is used. I found out that I could get it. A resin material reinforced with organic short fibers enhances the reinforcing effect in the bending direction, and since the organic short fibers are fine, the reinforcing effect in the compression direction is small. By using a resin and / or elastomer material having a high flexural rigidity and a low Shore D hardness for the cover as described above, the deformation of the cover becomes local when the golf ball is hit, and the contact area between the golf ball and the club face is large. As a result, the friction coefficient is increased and the spin performance is improved.
[0009]
On the other hand, when the flexural modulus is large and the Shore D hardness is high, local deformation does not occur, the contact area between the golf ball and the club face is small, and the spin performance is poor. Also, when the flexural rigidity is small and the Shore D hardness is low, the deformation is not local but extends to the entire golf ball, so the contact area is increased and the spin performance is improved. However, the rebound performance is reduced as the deformation amount is increased. . Accordingly, an object of the present invention is to provide a golf ball in which the cut resistance and the resilience performance are improved at the same time by defining the relationship between the value of the flexural modulus and the value of the Shore D hardness within a certain range. .
[0010]
[Means for Solving the Problems]
The present invention relates to a golf ball comprising a core and a cover covering the core, wherein the cover is a composition having a thermoplastic resin and / or a thermoplastic elastomer, and having a bending rigidity (MPa) of the composition. A golf ball characterized in that the value (A) and the value (B) of the Shore D hardness of the surface of the golf ball coated with the composition satisfy the following relationship:
[0011]
950 ≦ (25B−A) ≦ 1190
70 ≦ A ≦ 270
The cover composition preferably contains 1 to 10 parts by weight of organic short fibers with respect to 100 parts by weight of the polymer component.
[0012]
Further, an ionomer resin is preferably used as the thermoplastic resin, and a styrene thermoplastic elastomer is preferably used as the thermoplastic elastomer.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a golf ball comprising a core and a cover covering the core. The cover is a composition mainly composed of a thermoplastic resin and / or a thermoplastic elastomer as a polymer component.
[0014]
In the cover composition, the value (A) of the flexural modulus (MPa) and the value of the Shore D hardness (B) of the surface when the composition is coated on a golf ball first satisfy the following relationship: It is necessary.
[0015]
950 ≦ (25B−A) ≦ 1190
Here, when the value of (25B-A) exceeds 1190, the spin performance of the golf ball is inferior. On the other hand, when it is less than 950, the cut resistance and the resilience are inferior. The value of (25B-A) is preferably from 1050 to 1190, more preferably from 1145 to 1175.
[0016]
In addition, the value (A) of the bending rigidity of the composition used for the cover material of the present invention is 70 MPa to 270 MPa, preferably 100 MPa to 250 MPa, particularly 140 MPa to 190 MPa.
[0017]
When the value (A) of the bending rigidity is less than 70 MPa, the cut resistance is inferior. On the other hand, when it exceeds 270 MPa, the Shore D hardness is relatively high, the spin rate is decreased, and the shot feeling tends to be hard.
[0018]
Here, the bending rigidity was measured according to JIS K7106 after press-molding the cover composition into a 2 mm-thick flat plate (pressing the pellet at 150 ° C. for 2 minutes and further pressing for 20 minutes after cooling).
[0019]
The Shore D hardness value (B) is preferably selected in the range of 45 to 60. If the Shore D hardness is too low, the cut resistance and resilience performance will be reduced, while if it is too high, the impact will be great at the time of impact, and the shot feel and spin performance will be reduced. The Shore D hardness is more preferably selected in the range of 45 or more and 55 or less, particularly 50 or more and 55 or less.
[0020]
Here, the Shore D hardness is the portion other than the dimples on the surface of the golf ball.
It measured based on D-2240. The measurement was performed 5 times and the average value was taken.
[0021]
As the polymer component of the cover composition of the present invention, a thermoplastic elastomer, preferably a styrene-based thermoplastic elastomer is used. In addition, a urethane-based thermoplastic elastomer, an ester-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and an amide-based thermoplastic elastomer. A plastic elastomer or the like is used.
[0022]
The styrenic thermoplastic elastomer is a block copolymer having a soft segment and a hard segment in the molecule. A unit obtained from a conjugated diene compound as a soft segment, such as a butadiene block or an isoprene block. Here, as the conjugated diene compound, for example, one or more kinds can be selected from butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc., among which butadiene, isoprene and these. The combination of is preferable. As a component constituting the hard segment, one or more of styrene and its derivatives such as α-methylstyrene, vinyltoluene, p-tert-butylstyrene, 1,1-diphenylethylene, etc. were selected. It is a unit such as a styrene block obtained from a compound. Styrene block units are particularly preferred.
[0023]
Specific examples of the styrene-based thermoplastic elastomer include styrene-isoprene-butadiene-styrene block copolymer (SIBS structure), styrene-butadiene-styrene block copolymer (SBS structure), and a double bond portion of the butadiene. Hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS structure), styrene-isoprene-styrene block copolymer (SIS structure), hydrogenated styrene-ethylene-propylene-styrene with its isoprene double bond moiety Examples thereof include block copolymers (SEPS structure), styrene-ethylene-ethylene-propylene-styrene copolymers (SEEPS structure), and modified ones thereof.
[0024]
The content of styrene (or a derivative thereof) in the SIBS structure, SBS structure, SEBS structure, SIS structure, SEPS structure, and SEEPS structure is preferably 10 to 50% by weight, particularly 15 to 45% by weight in the copolymer. When the amount is less than 10% by weight, the cover tends to be soft and the cut resistance tends to be lowered. On the other hand, when the amount is more than 50% by weight, the shot feeling and controllability cannot be sufficiently maintained.
[0025]
In the present invention, a part of the SIBS structure, SBS structure, SEBS structure, SIS structure, SEPS structure, and SEEPS structure copolymer is modified with a functional group selected from an epoxy group, a hydroxyl group, an acid anhydride, and a carboxyl group. Modified products can be used.
[0026]
For example, a styrene-butadiene-styrene block copolymer (SBS structure) having a polybutadiene block containing an epoxy group is a block copolymer having polystyrene at both ends, and its intermediate layer is a polybutadiene containing an epoxy group. A styrene-isoprene-styrene block copolymer (SIS structure) having a polyisoprene block containing an epoxy group, which may be obtained by hydrogenating a part or all of the double bond of the polybutadiene portion, and Is a block copolymer having polystyrene at both ends, the intermediate layer of which is a polyisoprene containing an epoxy group, and even if one or all of the double bonds of the polyisoprene portion are hydrogenated. Good.
[0027]
As the epoxidized styrenic thermoplastic elastomer, those having an epoxy group equivalent in the range of 200 to 3000 can be used. When such an epoxidized thermoplastic elastomer is mixed with an ionomer resin or the like, a reaction occurs with a free carboxyl group of the ionomer resin, the strength of the cover composition is increased, and the cut resistance is further improved. When the epoxy equivalent is less than 200, the effect of the above cut resistance is small, whereas when the epoxy group equivalent is more than 3000, the reaction amount between the epoxy group and the free carboxyl group in the ionomer resin is too large, There is a possibility that the fluidity is deteriorated and it becomes difficult to mold the ball. Hydroxyl groups, acid anhydrides, and carboxyl groups are also introduced into the middle part or terminal of the molecular chain of the block copolymer.
[0028]
Next, the cover composition of the present invention can use a thermoplastic resin alone or a mixture of the thermoplastic elastomer and the thermoplastic resin as a polymer component. Here, the thermoplastic resin includes general-purpose resins such as ionomer resin, polyethylene, polypropylene, polystyrene, ABS resin, methacrylic resin, polyethylene terephthalate, ACS resin and polyamide, and ionomer resin is particularly preferable.
[0029]
The ionomer resin is, for example, a copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and is obtained by neutralizing at least a part of the carboxyl group with a metal ion. A binary copolymer or 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, Examples thereof include those obtained by neutralizing at least a part of the carboxyl group with a metal ion.
[0030]
As the composition ratio, when the base polymer of the ionomer resin is a binary copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, the α-olefin is 80 to 90 weights. %, The α, β-unsaturated carboxylic acid is preferably 10 to 20% by weight. When the base polymer is 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, the α-olefin Is 70 to 85% by weight, α, β-unsaturated carboxylic acid is preferably 5 to 30% by weight, and α, β-unsaturated carboxylic acid ester is preferably 10 to 25% by weight. In addition, these ionomer resins preferably have a melt index (MI) of 0.1 to 20, particularly 0.5 to 15. By setting the carboxylic acid content or the carboxylic acid ester content in the above range, the resilience can be enhanced.
[0031]
As said alpha olefin, ethylene, propylene, 1-butene, 1-pentene etc. are used, for example, and ethylene is especially preferable. Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, and acrylic acid and methacrylic acid are particularly preferable. Moreover, as unsaturated carboxylic acid ester, methyl, ethyl, propyl, n-butyl, isobutyl ester etc., such as acrylic acid, methacrylic acid, fumaric acid, and maleic acid, are used, for example, acrylic acid ester, methacrylic acid ester Is preferred.
[0032]
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 Examples of metal ions that neutralize at least a part of the carboxyl groups therein include sodium ions, lithium ions, zinc ions, magnesium ions, and potassium ions. And when ionomer resin is what neutralized at least one part of the carboxyl group in the binary copolymer of ethylene and acrylic acid or methacrylic acid with the metal ion, the high flow of the melt index is 3-7 Preferably it is of the type.
[0033]
Specific examples of the above ionomer resins are illustrated by trade names. As examples of binary copolymer ionomer resins commercially available from Mitsui DuPont Chemical Co., Ltd., Himilan 1555 (Na), Himilan 1557 (Zn), Himilan 1605 (Na) , High Milan 1706 (Zn), High Milan 1707 (Na), High Milan AM 7318 (Na), High Milan AM 7315 (Zn), High Milan AM 7317 (Zn), High Milan AM 7311 (Mg), High Milan MK 7320 (K), and Triple Weight Examples of combined ionomer resins include Himilan 1856 (Na), Himilan 1855 (Zn), Himilan AM7316 (Zn), and the like. Furthermore, as ionomer resins commercially available from DuPont, Surlyn 8945 (Na), Surlyn 8940 (Na), Surlyn 8945 (Na), Surlyn 9910 (Zn), Surlyn 9945 (Zn), Surlyn 7930 (Li), Surlyn 7940 (Li) and terpolymer ionomer resins include Surlyn AD8265 (Na) and Surlyn AD8269 (Na).
[0034]
Examples of ionomer resins commercially available from Exxon include Iotech 7010 (Zn) and Iotech 8000 (Na). In addition, Na, Zn, K, Li, Mg, etc. described in parentheses after the trade name of the ionomer resin indicate the metal species of these neutralized metal ions. In the present invention, the ionomer resin used for the cover composition 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. A mixture of two or more ionomer resins neutralized with metal ions may be used.
[0035]
In the present invention, by mixing a thermoplastic elastomer with a thermoplastic resin such as an ionomer resin, an appropriate rigidity is imparted to the cover composition, and a good shot feeling is obtained. In particular, when ionomer resin is mixed with functional group-modified styrene thermoplastic elastomer or urethane thermoplastic elastomer, the resilience performance of the cover composition is maintained by the reaction or interaction between the carboxyl group of the ionomer resin and the modified functional group. The cut resistance can be improved. Here, when an ionomer resin is used as the thermoplastic resin, the mixing ratio (S component / R component) of the ionomer resin (R component) and the thermoplastic elastomer (S component) is 0.1 to 2.0 by weight, preferably A range of 0.2 to 1.5, particularly 0.3 to 1.2 is preferred.
[0036]
Furthermore, it is desirable that the S component and the R component have the following relationship in weight ratio with respect to the polymer component (Q) of the cover material.
[0037]
(S component + R component) / Q component ≧ 0.5
The R component contributes to cut resistance and resilience performance, and the S component contributes to spin performance. Therefore, when the sum of the R component and the S component is less than 50% by weight of the polymer component, these characteristics cannot be maintained.
[0038]
Further, the value of (R component / Q component) is desirably 0.3 or more. The resilience performance is improved by mixing the ionomer resin (R component). However, when there are too many ionomer resins, components, such as a thermoplastic elastomer which contributes to spin performance, will decrease, and spin performance will fall. Preferably (R component / Q component) is 0.3 to 0.8, more preferably 0.3 to 0.6, and particularly 0.35 to 0.5.
[0039]
Examples of the organic short fibers used in the present invention include nylon fibers, acrylic fibers, polyester fibers, and aramid fibers. In order to improve the cut resistance without deteriorating the resilience performance, particularly the nylon fibers or the kevlar fibers are used. Fiber is preferred. When inorganic short fibers such as fibrous aluminum borate whiskers are used instead of organic short fibers, the difference in elastic modulus between the inorganic short fibers and the cover base material is large, and the inorganic short fibers when hitting a golf ball are surrounded by Since it cannot follow the deformation of the cover base material, energetic loss occurs at the interface between the two and the resilience performance decreases. On the other hand, in the case of organic short fibers, such an energy loss does not occur because it is close to the elastic modulus of the cover base material.
[0040]
In the present invention, in order to mix the organic short fiber with the thermoplastic elastomer, in order to enhance the adhesion between them, for example, when using an aramid (Kevlar) fiber, surface treatment with an epoxy resin, formalin-resorcin resin, etc. Affinity between the organic short fibers and the thermoplastic elastomer can be increased by mixing with the thermoplastic elastomer and then pelletizing, so-called master batch method.
[0041]
The length of the organic short fiber is 5 to 1000 μm, preferably 10 to 500 μm, and the diameter is 0.05 to 5 μm, preferably 0.1 to 1 μm. When the length of the organic short fiber is less than the above range, the strength in the bending direction is weak, the strength does not increase, and the cut resistance cannot be improved. Moreover, when the diameter of an organic short fiber is less than the said range, it only acts as a filler. On the other hand, when the length and diameter of the organic short fibers exceed the above ranges, the viscosity of the cover material increases and the moldability is impaired. In addition, in this invention, an organic short fiber is the concept containing the fiber finely cut | judged in the pulp form.
[0042]
The organic short fiber blended in the cover composition is in the range of 1 to 10 parts by weight with respect to 100 parts by weight of the polymer component. When the amount is less than 1 part by weight, the effect of blending the organic short fibers is small. The range is preferably 2 to 8 parts by weight, particularly 3 to 6 parts by weight. The value of (25B-A) can be adjusted to the range of 950 to 1190 by adjusting the blending amount of the organic short fibers.
[0043]
Next, in the present invention, a short amount of organic short fibers are mixed in advance with a polymer to form a short fiber reinforced polymer, and then kneaded into the cover composition. In this case, the organic short fibers are uniformly dispersed and mixed in the cover composition, and the cut resistance is further improved. Here, as the polymer mixed with the organic short fibers, natural rubber, butadiene rubber, styrene butadiene rubber, rubber such as NBR, EPDM, silicon rubber, epichlorohydrin rubber, resin such as low density polyethylene, or a mixture thereof can be used. . The blending amount of the short fibers in the short fiber reinforced polymer is set in the range of 10 to 100 parts by weight, preferably 20 to 70 parts by weight with respect to 100 parts by weight of the polymer component. The polymer component to be mixed here is included in the polymer component of the cover composition to set the blending amount of the organic short fibers in the cover composition. The polymer component in the cover composition means an ionomer resin, a thermoplastic elastomer, rubber or the like as a base polymer, and organic short fibers are not included in the polymer component.
[0044]
The cover composition of the present invention is obtained by adding a predetermined amount of organic short fibers to a thermoplastic elastomer, for example, a styrene thermoplastic elastomer such as SBS structure or SIS structure or a thermoplastic resin such as urethane thermoplastic elastomer and ionomer resin, and heating. By mixing, the desired cover composition is obtained. The heating and mixing is usually performed by heating and mixing at, for example, 150 to 260 ° C. using an internal mixer such as a kneading type twin screw extruder, Banbury or kneader.
[0045]
Further, in the present invention, in addition to the resin as a main component, the cover composition includes a filler such as barium sulfate, a colorant such as titanium dioxide, and other additives such as a dispersant, as necessary. Anti-aging agents, ultraviolet absorbers, light stabilizers, fluorescent materials or fluorescent whitening agents, and the like may be blended so long as the desired characteristics of the golf ball cover are not impaired.
[0046]
In the present invention, a thread wound core or a solid ball core such as a two-piece or a three-piece is used as the core, and can be employed for either a thread-wound ball or a solid ball. The core of the solid ball is composed of a cross-linked product of a rubber composition, and the rubber component of the rubber composition is suitably based on butadiene rubber having a cis-1,4-structure. However, in addition to the above butadiene rubber, for example, natural rubber, styrene butadiene rubber, isoprene rubber, chloroprene rubber, butyl rubber, ethylene propylene rubber, ethylene propylene diene rubber, acrylonitrile rubber and the like are 40 parts by weight or less with respect to 100 parts by weight of the rubber component. It may be blended with.
[0047]
As the crosslinking agent used in the rubber composition, for example, α, β-ethylenically unsaturated carboxylic acid such as acrylic acid and methacrylic acid and metal oxide such as zinc oxide are reacted during the preparation of the rubber composition. , Β-ethylenically unsaturated carboxylic acid metal salts, α, β-ethylenically unsaturated carboxylic acid metal salts such as zinc acrylate and zinc methacrylate, polyfunctional monomers, N, N'-phenyl bismaleimide, sulfur and the like which are usually used as a crosslinking agent can be mentioned, and a metal salt of an α, β-ethylenically unsaturated carboxylic acid, particularly a zinc salt is particularly preferable.
[0048]
For example, in the case of a metal salt of an α, β-ethylenically unsaturated carboxylic acid, the amount is preferably 20 to 40 parts by weight with respect to 100 parts by weight of the rubber component, while the α, β-ethylenically unsaturated carboxylic acid and the metal oxide are added. When reacting during the preparation of the rubber composition, 15 to 30 parts by weight of α, β-ethylenically unsaturated carboxylic acid and zinc oxide or the like with respect to 100 parts by weight of the α, β-ethylenically unsaturated carboxylic acid It is preferable to mix 15 to 35 parts by weight of metal oxide.
[0049]
As the filler used in the rubber composition, for example, one or more inorganic powders such as barium sulfate, calcium carbonate, clay, and zinc oxide can be used. The blending amount of these fillers is preferably in the range of 5 to 50 parts by weight with respect to 100 parts by weight of the rubber component.
[0050]
Further, for the purpose of improving workability and adjusting the hardness, a softening agent, liquid rubber, or the like may be appropriately blended, or an anti-aging agent may be blended as appropriate.
[0051]
As the crosslinking initiator, for example, organic peroxides such as dicumyl peroxide and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane are used. The amount of these crosslinking initiators is 0.1 to 5 parts by weight, particularly 0.3 to 3 parts by weight, based on 100 parts by weight of the rubber component.
[0052]
In the present invention, the core may be a single layer or a composite layer having different characteristics such as specific gravity and hardness. In this case, the composition of the core is not limited to the above description of the composition.
[0053]
And in the production of the core, the above-mentioned compounding materials are mixed using a roll, a kneader, a banbari, etc., and 145 ° C. to 200 ° C. under pressure using a mold, preferably 150 ° C. to 175 ° C. for 10 minutes to Vulcanize for 40 minutes to make the core. In order to improve the adhesion of the obtained core to the cover, an adhesive may be applied to the surface or the surface may be roughened.
[0054]
Here, the diameters of the wound core and the solid core are designed in the range of 36.8 to 41.4 mm, preferably 37.8 to 40.8 mm. If the thickness is less than 36.8 mm, the cover layer becomes thick and the resilience is lowered. On the other hand, if the thickness exceeds 41.4 mm, the cover layer becomes thin and molding becomes difficult.
[0055]
In the present invention, a known method can be used to mold the cover into the core. The cover composition is formed in advance into a hemispherical half-shell, and the two cores are used to wrap the core and press molded at 130-170 ° C. for 1-5 minutes, or the cover composition is directly applied onto the core. A method of wrapping the core by injection molding may be used. The cover has a thickness of 0.7 to 3.0 mm, preferably 1.0 to 2.5 mm. If it is smaller than 0.7 mm, there is a defect that cover cracks are likely to occur when it is repeatedly hit, and if it is larger than 3.0 mm, the shot feeling becomes worse. Furthermore, a large number of dimples are formed on the surface as necessary when molding the cover. The golf ball of the present invention is usually put on the market with a paint finish, a marking stamp, etc. in order to enhance aesthetics and increase commercial value.
[0056]
In the present invention, the cover may be a single layer, but may be configured as a multi-layer cover. The golf ball of the present invention is usually designed to have a ball diameter of 42.67 to 43.00 mm and a ball weight of 45.00 to 45.93 g.
[0057]
【Example】
Examples 1 to 3, Comparative Examples 1 to 7
(1) Production of thread wound core
A core rubber composition containing butadiene rubber as a main component was kneaded and heated and pressed in a mold at a predetermined temperature for a predetermined time to produce a solid core having a diameter of 28 mm. Further, thread rubber was wound around the core in a stretched state to produce a thread wound core having a diameter of 40 mm.
[0058]
(2) Preparation of cover composition
The cover composition shown in Table 1 was mixed with a twin-screw kneading extruder and extruded at a cylinder temperature of 180 ° C. with a twin-screw extruder. It is important that the extrusion temperature is not higher than the melting point of the organic short fiber. Extrusion conditions are
Screw diameter: 45mm
Screw rotation speed: 200rpm
Screw L / D: 35
And the blend was heated to 195-205 ° C at the die position of the extruder.
[0059]
The cover composition is used to injection-mold a hemispherical half shell, and the two cores are used to wrap the core, followed by press hot compression molding at 150 ° C. for 2 minutes in a mold, and after cooling, golf The ball was taken out. Thereafter, a paint was applied to the surface to produce a golf ball having a diameter of 42.8 mm and a weight of 45.4 g.
[0060]
The characteristics of the golf ball were evaluated by the following method.
(I) Spin performance (spin retention)
A sand wedge club was attached to a swing robot manufactured by True Temper, a golf ball was hit at a head speed of 20 m / sec, and the amount of spin was determined by taking continuous photographs of marks applied to the hit golf ball. The measurement was performed under normal dry conditions and wet conditions in which the ball and club face were wet with water. The spin retention rate is defined as (wet spin amount) / (dry spin amount) × 100. The larger the number, the better.
[0061]
(Ii) Rebound performance
A golf ball placed in front is hit with a stainless steel cylinder launched at a speed of 45 m / sec, and the speed of each object before and after the collision is read and calculated with a laser. The relative value with Comparative Example 1 as 100 is displayed as the rebound index. The larger the number, the better.
[0062]
(Iii) Cut resistance
The golf ball was hit with a pitching wedge intentionally, and the size of the cut was evaluated by a 5-point method. Five points are almost intact and one point indicates that the scratches were large.
[0063]
[Table 1]

[0064]
Note 1) Surlyn 9945: Zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin, MI = 5.2
Note 2) Surlyn 8945: Sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin, MI = 4.8
Note 3) HG252: Kuraray thermoplastic elastomer (SEPS)
Note 4) TP301: Trans polyisoprene rubber manufactured by Kuraray
Note 5) LA1060: Nylon short fiber reinforced natural rubber manufactured by Ube Industries, Ltd.
Natural rubber / low density polyethylene / nylon 6 short fiber = 100/75/87 (weight ratio): diameter of organic short fiber; 0.2 μm The amount of organic short fiber is shown in parentheses.
Note 6) Titanium oxide A220 manufactured by Ishihara Sangyo Co., Ltd.
Note 7) Barium sulfate BMH manufactured by Sakai Chemical
Note 8) In Comparative Examples 6 and 7, 2 parts by weight of sulfur and 1 part by weight of vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., Noxeller M (mercaptobenzothiazole) are blended.
[0065]
Table 1 shows the measurement results of the golf balls of Examples 1 to 3 and Comparative Examples 1 to 7.
[0066]
Comparative Examples 1 to 6 are cover compositions in which organic short fibers are not blended with polymer components such as thermoplastic elastomers, and the value of (25B-A) is out of 950 to 1190, and the spin performance or cut resistance is Either is inferior.
[0067]
The comparative example 7 uses the cover composition which mix | blended organic short fiber with things other than thermoplastic resins, such as ionomer resin, as a polymer component, and its cut resistance is inferior.
[0068]
Examples 1 to 3 are cover compositions in which organic short fiber reinforced rubber is blended, and the values of (25B-A) and A are both set within predetermined ranges, so the resilience performance and cut resistance And spin performance is excellent overall.
[0069]
It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0070]
【The invention's effect】
The golf ball of the present invention uses a thermoplastic elastomer and / or a thermoplastic resin as the polymer component of the cover composition as a polymer component, and blends a predetermined amount of organic short fibers to thereby determine the flexural rigidity and Shore D hardness. Therefore, a golf ball with excellent cut resistance can be obtained while maintaining the resilience performance and easily applying a spin amount when hit with a rough iron.

Claims (4)

A core, a golf ball comprising a cover covering the core, wherein the cover, have a thermoplastic resin and / or thermoplastic elastomer, the polymer component 100 parts by weight, 1 to 10 parts by weight of the organic short fiber In which the bending rigidity (MPa) value (A) of the composition and the Shore D hardness value (B) of the surface when the composition is coated on a golf ball are included. Satisfies the following relationship: a golf ball.
1145 ≦ (25B−A) ≦ 1175
140 ≦ A ≦ 190   The golf ball according to claim 1, wherein the thermoplastic elastomer is a styrenic thermoplastic elastomer.   The golf ball according to claim 1, wherein the thermoplastic resin is an ionomer resin. The golf ball according to claim 3, wherein a mixing ratio (thermoplastic elastomer / ionomer resin) of the thermoplastic elastomer and the ionomer resin is 0.1 to 2.0 by weight.