JP3575524B2 - Multi-piece solid golf ball - Google Patents

Description

＊：日本合成ゴム社製 ＢＲ０１
【００５８】
【表２】

＊１：「ハイトレル」東レ・デュポン社製ポリエステル系エラストマー
＊２：「ペバックス」アトケム社製ポリアミド系エラストマー
＊３：「プリマロイ」三菱化学工業（株）製ポリエステル系エラストマーを主成分とするアロイ材料
＊４：「ＨＰＲ」三井・デュポン社製エチレン・エチルアクリレート共重合体樹脂の無水マレイン酸グラフト変性物
＊５：「タフテック」旭化成社製スチレン系エラストマー
＊６：「ハイミラン」三井・デュポンポリケミカル社製アイオノマー樹脂
＊７：「サーリン」デュポン社製アイオノマー樹脂
【００５９】
【表３】

＊６：「ハイミラン」三井・デュポンポリケミカル社製アイオノマー樹脂
＊７：「サーリン」デュポン社製アイオノマー樹脂
【００６０】
【表４】

＊８：コア＋中間層
【００６１】
【表５】

＊８：コア＋中間層
【００６２】
表４，５の結果から明らかなように、比較例１〜５のボールはいずれも中間層のショアＤ硬度が４０以上であり、カバーと中間層の硬度差が２５未満であると共に、カバーに無機充填剤として二酸化チタンを５．６重量部しか含まないため、本願発明の作用効果を奏し得ないものである。
【００６３】
即ち、比較例１は特開平７−２４０８４号公報と同じタイプのスリーピースボールであり、ドライバーショット時の飛距離は比較的増大するが、パターの打感が硬く劣るものである。
【００６４】
比較例２は特開平４−２４４１７４号公報と同じタイプのスリーピースボールであり、ドライバーショット時の飛距離が低下し、打感も硬く劣るものである。
【００６５】
比較例３は特開平６−２３０６９号公報と同じタイプのスリーピースボールであり、ドライバーショット時の飛距離の低下と、ドライバー、９番アイアン、パターのいずれにおいても打感が硬く劣るものである。
【００６６】
比較例４は特開平９−１０３５８号公報と同じタイプのスリーピースボールであり、ドライバーショット時の飛距離が低下し、打感も硬く劣るものである。
【００６７】
比較例５は特開平９−３１３６４３号公報と同じタイプのスリーピースボールであり、ドライバーショット時の飛距離は比較的増大するが、ドライバーでの打感が硬く劣るものである。
【００６８】
また、比較例６は軟らかいタイプのツーピースソリッドゴルフボールであり、ドライバーショット時の飛距離が低下すると共に、連続打撃耐久性が著しく劣るものである。
【００６９】
これに対して、実施例１〜７のスリーピースボールは、ドライバー、９番アイアン、パターのいずれにおいても軟らかく良好な打感を有すると共に、ドライバーでのフルショット時の飛距離が飛躍的に増大し、優れた連続打撃耐久性を有するものである。
【図面の簡単な説明】
【図１】本発明の一実施例に係るマルチピースソリッドゴルフボールの断面図である。
【符号の説明】
１ ソリッドコア
２ 中間層
３ カバー
Ｇ ゴルフボール[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-piece solid golf ball having at least a three-layer structure including a solid core, an intermediate layer, and a cover. The golf ball has a soft and good feel when approaching and putting, and has excellent continuous hitting durability and a driver. The present invention relates to a multi-piece solid golf ball whose flight distance increases at the time of a full shot.
[0002]
Problems to be solved by the prior art and the invention
Conventionally, many two-piece solid golf balls have a ballistic trajectory called a so-called ball ball for both driver shots and iron shots compared to thread-wound golf balls, and their spin characteristics make it hard to spin, resulting in more runs. This has the advantage that the total flight distance increases.
[0003]
On the other hand, a two-piece solid golf ball tends to be harder to stop on a green and less controllable than a thread-wound golf ball because it is harder to spin on an iron shot than a thread-wound golf ball.
[0004]
On the other hand, a golf ball is required to have a soft feel at the time of hitting as the flight distance increases, and without this, the commercial value is impaired. In general, thread-wound golf balls have structural characteristics that are softer and provide a better feel when compared to two-piece solid golf balls.
[0005]
For this reason, it is common practice to soften the ball structure of a two-piece solid golf ball composed of a core and a cover in order to achieve a soft feel when hit.
[0006]
However, such a soft type two-piece solid golf ball generally uses a soft core, but if the core is too soft, the resilience is reduced, the flying performance is reduced, and the durability is significantly reduced. In addition to being unable to obtain the excellent flight performance and durability characteristic of the two-piece solid golf ball, there has been a problem that it becomes difficult to withstand actual use.
[0007]
Recently, in order to solve such problems, many three-piece solid golf balls having an intermediate layer between a core and a cover have been proposed (JP-A-7-24084, JP-A-6-23069). And JP-A-4-244174, JP-A-9-10358, and JP-A-9-313543.
[0008]
However, also in these proposals, if the cover and the intermediate layer are formed softly, the feeling becomes soft, but the flight distance at the time of a full shot with a driver is reduced. Conversely, if it is desired to obtain a flight distance, the cover and the intermediate layer must be formed hard, resulting in a reduced hit feeling at the time of approach shot and putting. Golf balls have not yet been obtained, and further improvements have been desired.
[0009]
The present invention has been made in view of the above circumstances, and has at least a three-layered multi-piece solid golf ball having a solid core, an intermediate layer, and a cover, and has a very soft and good feel when approaching and putting. It is another object of the present invention to provide a multi-piece solid golf ball having excellent continuous hitting durability and excellent flight performance at the time of a full shot with a driver.
[0010]
Means for Solving the Problems and Embodiments of the Invention
As a result of intensive studies to achieve the above object, the present inventor has found that in a multi-piece solid golf ball having at least a three-layer structure including a solid core, an intermediate layer and a cover, a relatively soft core and an extremely soft core are used. By combining a soft intermediate layer with a relatively hard cover and adding an appropriate amount of inorganic filler to the cover, it has a very soft feel when approaching and putting, and has excellent continuous impact durability. And that a multi-piece solid golf ball having excellent flight performance at the time of a full shot with a driver can be obtained.
[0011]
That is, in a multi-piece solid golf ball having a solid core, at least one intermediate layer covering the core, and at least one cover covering the intermediate layer, (i) preferably the solid core is a rubber base material. Is formed as a main material, the specific gravity is 1.0 to 1.3, and the amount of deformation when a load of 100 kg is applied to the core is 3.0 mm or more, so that the core is relatively soft, and (ii) the core is coated. A very soft thermoplastic resin having a Shore D hardness of 8 to 35, particularly (A) a thermoplastic polyester elastomer, (B) an olefin elastomer and a modified product thereof, and a styrene block copolymer. A heated mixture obtained by mixing one or more thermoplastic elastomers selected from the hydrogenated product is formed as a main material, or (B (Iii) forming a cover covering the intermediate layer from a relatively hard thermoplastic resin, particularly an ionomer resin having a Shore D hardness of 57 or more; The cover is formed so that the Shore D hardness of the cover is higher than the Shore D hardness of the intermediate layer by 25 or more, and (iv) an appropriate amount of an inorganic filler is added to the cover so that the specific gravity of the cover is 1.01 to 1.4. By setting it in the range, the decrease in durability due to the softly formed intermediate layer can be compensated for, and these (i) to (iv) act synergistically to be very soft at the time of approach shot and putting. Unprecedented multi-piece software with excellent feeling, excellent durability in continuous hitting and excellent flight performance in full shot with driver It found that the head golf ball can be obtained, in which the present invention has been completed.
[0012]
Therefore, the present invention
(1) A multi-piece solid golf ball comprising a solid core formed from a rubber composition, at least one intermediate layer covering the core, and at least one cover covering the intermediate layer. Is formed mainly of a thermoplastic resin having a Shore D hardness of 8 to 35, and the cover is made of a cover material obtained by adding 15 to 40 parts by weight of an inorganic filler to 100 parts by weight of the thermoplastic resin. A multi-piece solid formed so as to have a hardness of at least 57, wherein the Shore D hardness of the cover is at least 25 higher than the Shore D hardness of the intermediate layer, and the specific gravity of the cover is in the range of 1.01 to 1.4. Golf ball,
(2) The solid core is formed mainly of a rubber base material, has a specific gravity of 1.0 to 1.3, a diameter of the solid core of 25 to 40 mm, and applies a load of 100 kg to the solid core. The multi-piece solid golf ball according to (1), wherein the deformation amount when the golf ball is not less than 3.0 mm.
(3) The multi-piece solid golf ball according to (1) or (2), wherein the cover is formed mainly of an ionomer resin.
(4) The multi-piece solid golf ball according to any one of (1) to (3), wherein the intermediate layer has a thickness of 0.2 to 5.0 mm and a specific gravity of 0.8 or more.
(5) The multi-piece solid golf ball according to any one of (1) to (4), wherein the cover has a thickness of 1.0 to 5.0 mm.
(6) The intermediate layer is formed of one or more thermoplastic elastomers selected from olefin-based elastomers and modified products thereof, and styrene-based block copolymers and hydrogenated products thereof. ) The multi-piece solid golf ball according to any one of (1) to (5),
(7) Heating of the intermediate layer with a thermoplastic polyester elastomer and one or more thermoplastic elastomers selected from olefin elastomers and modified products thereof, and styrene block copolymers and hydrogenated products thereof The multi-piece solid golf ball according to any one of (1) to (6), which is formed of a mixture.
(8) The multi-piece solid golf ball according to any one of (1) to (7), wherein the intermediate layer has a Shore D hardness of 10 to 29.
I will provide a.
[0013]
Hereinafter, the present invention will be described in more detail. As shown in FIG. 1, a multi-piece solid golf ball G of the present invention comprises a solid core 1, at least one intermediate layer 2 covering the core 1, And at least one cover 3 for covering the layer 2.
[0014]
The solid core 1 can be formed from a rubber composition mainly composed of a base rubber mainly composed of polybutadiene rubber, polyisoprene rubber, natural rubber, and silicone rubber. Is preferably a polybutadiene rubber. As the polybutadiene rubber, cis-1,4-polybutadiene having a cis structure of at least 40% or more is preferable. In addition, in the base rubber, natural rubber, polyisoprene rubber, styrene butadiene rubber, and the like can be appropriately blended with the polybutadiene, if desired. However, by increasing the polybutadiene rubber component, the resilience of the golf ball is improved. Therefore, the rubber component other than polybutadiene is preferably not more than 10 parts by weight based on 100 parts by weight of polybutadiene.
[0015]
The rubber composition may contain, in addition to the rubber component, a crosslinking agent such as zinc salts of unsaturated fatty acids such as zinc methacrylate and zinc acrylate, and magnesium salts and ester compounds such as trimethylpropane methacrylate. Zinc acrylate can be suitably used because of its height. The compounding amount of these crosslinking agents is preferably 15 to 40 parts by weight based on 100 parts by weight of the base rubber.
[0016]
Further, the rubber composition usually contains a vulcanizing agent such as dicumyl peroxide or a mixture of dicumyl peroxide and 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane. The vulcanizing agent can be used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the base rubber.
[0017]
The rubber composition may further contain, if necessary, an antioxidant or a filler for adjusting specific gravity, such as zinc oxide or barium sulfate. The amount of these fillers is 100 wt. 0 to 130 parts by weight per part.
[0018]
The rubber composition for a core is kneaded using a usual kneader (for example, a Banbury mixer, a kneader, a roll, or the like), and the obtained compound is formed by injection molding or compression molding using a core mold. be able to.
[0019]
The solid core thus obtained has a diameter of preferably 25 to 40 mm, more preferably 27 to 39 mm, still more preferably 30 to 38 mm, and a weight of 10 to 40 g, preferably 15 to 35 g, more preferably Is 20 to 32 g, and specific gravity is 1.0 to 1.3, preferably 1.03 to 1.28, more preferably 1.06 to 1.25.
[0020]
Further, the amount of deformation when a load of 100 kg is applied to the solid core is 3.0 mm or more, preferably 3.2 to 7.0 mm, more preferably 3.4 to 6.5 mm, and still more preferably 3.6 to 6 mm. 0.0 mm. If the amount of deformation is less than 3.0 mm, the feeling may be hard, while if it exceeds 7.0 mm, the resilience may decrease.
[0021]
Note that the core may have a single-layer structure made of one kind of material or a multi-layer structure made up of two or more layers made of different materials.
[0022]
In the present invention, at least one, preferably one or two intermediate layers 2 are formed around the core 1. The intermediate layer 2 is formed mainly of a very soft thermoplastic resin having a Shore D hardness of 8 to 35. By forming an unusually soft intermediate layer between the core and the cover in this way, a very soft and good feeling can be realized during approach shots and putting.
[0023]
As the thermoplastic resin of the intermediate layer, one or two kinds selected from (A) a thermoplastic polyester-based elastomer and (B) an olefin-based elastomer and a modified product thereof, and a styrene-based block copolymer and a hydrogenated product thereof are used. The heated mixture with the above thermoplastic elastomer or the thermoplastic elastomer of the component (B) can be used alone.
[0024]
Here, the thermoplastic polyester-based elastomer of the component (A) is synthesized from terephthalic acid, 1,4-butanediol and polytetramethylene glycol (PTMG) or polypropylene glycol (PPG), and has a polybutylene terephthalate (PBT) portion. Is a hard segment, and a polyetherester-based multi-block copolymer having a polytetramethylene glycol (PTGM) or polypropylene glycol (PPG) portion as a soft segment is preferable. Specifically, commercially available products such as Hytrel 3078, Hytrel 4047, Hytrel 4767 (manufactured by Toray DuPont) can be used.
[0025]
As the olefin elastomer of the component (B), a copolymer of ethylene and an alkene having 3 or more carbon atoms, preferably a copolymer of ethylene and an alkene having 3 to 10 carbon atoms, or an α-olefin and an alkene Examples include a saturated carboxylic acid ester and a polymerizable monomer containing a carboxyl group or a carboxylic anhydride group. Examples of the olefin elastomer include ethylene-propylene copolymer rubber, ethylene-butene copolymer rubber, ethylene-hexene copolymer rubber, and ethylene-octene copolymer rubber. Further, ethylene-propylene-non-conjugated dienes such as 5-ethylidene norbornene, 5-methylnorbornene, 5-vinylnorbornene, dicyclopentadiene, butene, and the like are added as the third component. -Propylene-butene copolymer rubber, ethylene-ethyl acrylate copolymer resin and the like.
[0026]
Specific examples of such olefin-based elastomers include “MITUI EPT”, “Tuffmer” (manufactured by Mitsui Petrochemical Industries), “ENGAGE” (manufactured by Dow Chemical Japan), and “Dynalon” (Nippon Synthetic Rubber Commercially available products, such as those manufactured by the company.
[0027]
Further, modified products of the above-mentioned olefin-based elastomers can also be suitably used.Examples of such modified olefin-based elastomers include those obtained by graft-modifying maleic anhydride on an ethylene-ethyl acrylate copolymer resin. Specifically, commercially available products such as "HPR" (manufactured by DuPont-Mitsui Polychemicals) can be used.
[0028]
Next, as the styrene-based block copolymer, a polymer whose conjugated diene block is composed of butadiene alone, isoprene alone, or a mixture of isoprene and butadiene is preferable. Further, hydrogenated products of these styrene block copolymers can be suitably used, for example, hydrogenated products of styrene-butadiene-styrene block copolymer, hydrogenated products of styrene-isoprene-styrene block copolymer, and the like. Is mentioned.
[0029]
Specific examples of the hydrogenated product of such a styrene conjugated diene block copolymer include “Dynalon” (manufactured by Nippon Synthetic Rubber Co., Ltd.), “Septon”, “Hibler” (manufactured by Kuraray), and “Toughtec” ( Commercial products such as Asahi Kasei Kogyo Co., Ltd.) can be used.
[0030]
The intermediate layer of the present invention comprises one or more selected from the group consisting of (A) a thermoplastic polyester elastomer, (B) an olefin elastomer and a modified product thereof, and a styrene block copolymer and a hydrogenated product thereof. In this case, the mixing ratio of the two components is 95% by weight or less for the component (A), and preferably 95 to 0/5 to 100% by weight for the component (A) / (B). %, More preferably 90 to 5/10 to 95% by weight, even more preferably 80 to 10/20 to 90% by weight.
[0031]
As such a mixture of the components (A) and (B), commercially available products can be used, and for example, "Primalloy" (manufactured by Mitsubishi Chemical Corporation) and the like can be mentioned.
[0032]
Further, a thermoplastic elastomer obtained by singly or in combination of two or more kinds selected from the olefin-based elastomer (B) component and its modified product, and the styrene-based block copolymer and its hydrogenated product is used as the intermediate layer. Can be used as the main material.
[0033]
In addition, a weight adjuster, a colorant, a dispersant, and the like can be added to the intermediate layer composition, if necessary, in addition to the resin component.
[0034]
The method for coating the intermediate layer around the core is not particularly limited, and ordinary injection molding or compression molding can be employed.
[0035]
The intermediate layer thus formed needs to have a Shore D hardness of 8 to 35, preferably 9 to 30, more preferably 10 to 29, still more preferably 12 to 27, and most preferably. 15 to 24. If the Shore D hardness is less than 8, the intermediate layer becomes too soft, the resilience and durability are reduced, and it becomes difficult to use. On the other hand, if the Shore D hardness exceeds 35, the intermediate layer becomes too hard, and the shot feeling at the time of approach shot and putting becomes too hard to achieve the object of the present invention.
[0036]
Further, the thickness of the intermediate layer is preferably 0.2 to 5.0 mm, more preferably 0.5 to 4.0 mm, still more preferably 0.7 to 3.5 mm, and the specific gravity is 0.8 or more, preferably 0.85 to 1.4, more preferably 0.87 to 1.2, still more preferably 0.89 to 1.15.
[0037]
Next, a cover 3 is formed around the intermediate layer 2 in at least one layer, preferably one layer or two layers. The cover 3 is formed mainly of a thermoplastic resin having a Shore D hardness of 25 or more than the intermediate layer.
[0038]
The cover can be formed using a usual thermoplastic resin as a main material, and examples thereof include an ionomer resin, a polyester elastomer, a polyamide elastomer, a styrene elastomer, a polyurethane elastomer, an olefin elastomer, and a mixture thereof. However, an ionomer resin is particularly preferred. Specifically, commercially available products such as "Himilan" (manufactured by Dupont Mitsui Polychemicals) and "Surlyn" (manufactured by Dupont) can be used. Note that a UV absorber, an antioxidant, a dispersant such as metal soap, or the like can be added to the cover material as needed.
[0039]
The method for coating the cover around the intermediate layer is not particularly limited, and ordinary injection molding or compression molding can be employed.
[0040]
In this way, the cover has a Shore D hardness of 57 or more, preferably 58 to 70, more preferably 59 to 68, and still more preferably 60 to 65. The hardness of the cover needs to be 25 or more higher in Shore D than the hardness of the intermediate layer, preferably 25 to 50, and more preferably 29 to 45. If the hardness difference between the cover and the intermediate layer is less than 25, the cover will be soft and the resilience will be reduced. On the other hand, if it exceeds 50, the difference in hardness becomes too large, and the durability is reduced. In addition, the energy loss is increased, and the flight distance may be reduced.
[0041]
The cover has a thickness of 1.0 to 5.0 mm, preferably 1.2 to 4.0 mm, more preferably 1.3 to 3.0 mm, and still more preferably 1.4 to 2.5 mm.
[0042]
In the present invention, an appropriate amount of an inorganic filler is added to the cover. By adding the inorganic filler to the cover in this way, it is possible to effectively compensate for the decrease in durability due to the very soft formation of the intermediate layer.
[0043]
In this case, the inorganic filler is added in an amount of 5 to 40 parts by weight, preferably 15 to 38 parts by weight, more preferably 18 to 36 parts by weight based on 100 parts by weight of the resin component forming the cover. If the amount of the inorganic filler is less than 5 parts by weight, the reinforcing effect may not be obtained, while if it exceeds 40 parts by weight, dispersibility and resilience may be adversely affected.
[0044]
The average particle size of the inorganic filler is usually 0.01 to 100 μm, preferably 0.1 to 10 μm, more preferably 0.1 to 1.0 μm. If the average particle size is too small or too large, the dispersibility at the time of filling will be deteriorated, and the effect of the present invention may not be achieved.
[0045]
Such an inorganic filler is not particularly limited, and includes, for example, barium sulfate, titanium dioxide, calcium carbonate, tungsten, and the like. One of these can be used alone, or two or more can be used in combination. Particularly, barium sulfate and titanium dioxide are preferred.
[0046]
When the inorganic filler is added to the cover in this way, the specific gravity of the cover to which the inorganic filler is added is 1.01 to 1.4, preferably 1.05 to 1.3, and more preferably 1.1 to 1.3. .2.
[0047]
In addition, an appropriate amount of an inorganic filler can be added to the intermediate layer, and by adding the inorganic filler to both the cover and the intermediate layer as described above, the durability can be further improved. .
[0048]
In this case, the amount of the inorganic filler to be added is 5 to 40 parts by weight, preferably 15 to 38 parts by weight, based on 100 parts by weight of the resin component forming the intermediate layer. Are the same as in the case of the cover.
[0049]
The multi-piece solid golf ball of the present invention has the above configuration, and includes a relatively soft core, a very soft intermediate layer covering the core, and a relatively hard cover covering the intermediate layer. By combining and adding an appropriate amount of an inorganic filler to the cover and further to the intermediate layer, these are combined to have a very soft and good feeling during approach shots and putting, and excellent continuous impact durability. It has excellent flight performance during a full shot with a driver.
[0050]
In the golf ball of the present invention, a large number of dimples are formed on the surface, and the surface can be subjected to a finishing treatment such as painting and stamping as necessary. The hardness of the entire ball is preferably 2.6 to 5.5 mm, more preferably 2.8 to 4.8 mm in terms of deformation when a load of 100 kg is applied, and the ball diameter and weight are in accordance with R & A Golf Rules. In accordance with the above, a diameter of 42.67 mm or more and a weight of 45.93 g or less can be formed.
[0051]
【The invention's effect】
According to the present invention, it is possible to obtain a multi-piece solid golf ball that has a soft and good feeling at the time of approach shot and putting and has excellent flight performance and excellent continuous hitting durability at the time of a full shot with a driver.
[0052]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The amounts in Tables 1, 2 and 3 are all parts by weight.
[0053]
(Examples, Comparative Examples)
Examples 1 to 7 and Comparative Examples 1 to 6 were obtained by kneading the core rubber composition having the composition shown in Table 1 with a kneader, and vulcanizing the mixture in a core mold at a temperature of 155 ° C. for about 15 minutes. Created a solid core.
[0054]
The intermediate layer material shown in Table 2 and the cover material shown in Table 3 were formed around the obtained core by injection molding, respectively, and three-pieces of Examples 1 to 7 and Comparative Examples 1, 2, 4, and 5 were formed. A solid golf ball was created.
[0055]
In the three-piece ball of Comparative Example 3, a pair of half shells were previously formed with the intermediate layer material shown in Table 2, and the cores were covered with these half shells, and this was vulcanized in a mold at 155 ° C. for 15 minutes. In this manner, a double solid core was prepared, and a cover was formed around the double core by injection molding. Comparative Example 6 is a two-piece golf ball having a core and a cover without an intermediate layer.
[0056]
Next, the properties of the obtained golf ball were evaluated by the methods shown below. The results are also shown in Tables 4 and 5.
Solid core deformation
It was represented by the amount of deformation (mm) of the core when a load of 100 kg was applied to the core.
Flying performance
At a head speed of 45 m / sec (HS45), the club was carried by a swing robot manufactured by Miyama Corporation using a driver (# W1) (“PRO230Titan” loft 10 degrees (Bridgestone Sports Co., Ltd.)). The total flight distance and spin amount were measured. The same spin amount was used when the club was hit with a head speed of 33 m / sec (HS33) instead of a ninth iron (# I9) ("MODEL 55-HM" loft 44 degrees (manufactured by Bridgestone Sports Corp.)). Was measured.
Feel
Five professional golfers evaluated the feel when actually hitting with a driver (# W1), a 9th iron (# I9) and a putter (#PT) as a club according to the following criteria.
○: very soft
△: Normal
×: Hard
Continuous impact durability
The resulting ball was repeatedly hit with a swing robot manufactured by Miyama Co., Ltd. at a head speed of 45 m / sec (HS45) using a driver (“PRO230 Titan Loft 10 °” (Bridgestone Sports Co., Ltd.)). The condition of the surface was relatively evaluated according to the following criteria according to the number of hits.
○: No problem at all
△: Destruction relatively early
×: Early destruction
[0057]
[Table 1]

*: BR01 made by Nippon Synthetic Rubber Co., Ltd.
[0058]
[Table 2]

* 1: "Hytrel" polyester elastomer manufactured by Toray DuPont
* 2: "Pebax" polyamide elastomer manufactured by Atochem
* 3: “Primalloy” is an alloy material mainly composed of polyester elastomer manufactured by Mitsubishi Chemical Corporation.
* 4: "HPR" maleic anhydride graft modified ethylene-ethyl acrylate copolymer resin manufactured by DuPont-Mitsui.
* 5: "Tuftec" styrene elastomer manufactured by Asahi Kasei Corporation
* 6: "Himilan" ionomer resin manufactured by DuPont-Mitsui Polychemicals
* 7: “Sarlin” ionomer resin manufactured by DuPont
[0059]
[Table 3]

* 6: "Himilan" ionomer resin manufactured by DuPont-Mitsui Polychemicals
* 7: “Sarlin” ionomer resin manufactured by DuPont
[0060]
[Table 4]

* 8: Core + middle layer
[0061]
[Table 5]

* 8: Core + middle layer
[0062]
As is clear from the results of Tables 4 and 5, in all of the balls of Comparative Examples 1 to 5, the Shore D hardness of the intermediate layer was 40 or more, the hardness difference between the cover and the intermediate layer was less than 25, and Since it contains only 5.6 parts by weight of titanium dioxide as an inorganic filler, the function and effect of the present invention cannot be exhibited.
[0063]
That is, Comparative Example 1 is a three-piece ball of the same type as that of Japanese Patent Application Laid-Open No. Hei 7-24084, in which the flight distance at the time of driver shot is relatively increased, but the putter hit feeling is hard and inferior.
[0064]
Comparative Example 2 is a three-piece ball of the same type as in Japanese Patent Application Laid-Open No. 4-244174, in which the flight distance at the time of driver shot is reduced and the hit feeling is hard and poor.
[0065]
Comparative Example 3 is a three-piece ball of the same type as that of JP-A-6-23069, which has a reduced flight distance when shot with a driver and a hard and inferior hit feeling with any of the driver, 9-iron and putter.
[0066]
Comparative Example 4 is a three-piece ball of the same type as in Japanese Patent Application Laid-Open No. 9-10358, in which the flight distance at the time of driver shot is reduced and the hit feeling is hard and poor.
[0067]
Comparative Example 5 is a three-piece ball of the same type as that of Japanese Patent Application Laid-Open No. 9-313643, in which the flight distance at the time of driver shot is relatively increased, but the hit feeling with the driver is hard and inferior.
[0068]
Comparative Example 6 is a soft type two-piece solid golf ball, which has a reduced flight distance on driver shots and a remarkably poor continuous hitting durability.
[0069]
On the other hand, the three-piece balls of Examples 1 to 7 have a soft and good hit feeling with any of the driver, the 9-iron, and the putter, and the flying distance at the time of a full shot with the driver is dramatically increased. And has excellent continuous impact durability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multi-piece solid golf ball according to one embodiment of the present invention.
[Explanation of symbols]
1 solid core
2 Middle layer
3 Cover
G golf ball

Claims (8)

A multi-piece solid golf ball comprising a solid core formed from a rubber composition, at least one intermediate layer covering the core, and at least one cover covering the intermediate layer, wherein the intermediate layer has a Shore D The cover is formed mainly of a thermoplastic resin having a hardness of 8 to 35, and the cover is made of a cover material obtained by adding 15 to 40 parts by weight of an inorganic filler to 100 parts by weight of the thermoplastic resin, and has a Shore D hardness of 57 or more. And a cover having a Shore D hardness of at least 25 higher than the Shore D hardness of the intermediate layer, and a specific gravity of the cover in the range of 1.01 to 1.4. The solid core is formed mainly of a rubber base material, the specific gravity thereof is 1.0 to 1.3, the diameter of the solid core is 25 to 40 mm, and a load of 100 kg is applied to the solid core. The multi-piece solid golf ball according to claim 1, wherein the deformation amount is 3.0 mm or more. 3. The multi-piece solid golf ball according to claim 1, wherein the cover is formed mainly of an ionomer resin. The multi-piece solid golf ball according to any one of claims 1 to 3, wherein the intermediate layer has a thickness of 0.2 to 5.0 mm and a specific gravity of 0.8 or more. The multi-piece solid golf ball according to any one of claims 1 to 4, wherein the cover has a thickness of 1.0 to 5.0 mm. 6. The intermediate layer is formed of one or more thermoplastic elastomers selected from olefin-based elastomers and modified products thereof, and styrene-based block copolymers and hydrogenated products thereof. The multi-piece solid golf ball according to any one of the above items. The intermediate layer is formed by a heated mixture of a thermoplastic polyester elastomer, one or more thermoplastic elastomers selected from olefin elastomers and modified products thereof, and styrene block copolymers and hydrogenated products thereof. The multi-piece solid golf ball according to any one of claims 1 to 6, wherein the golf ball is a golf ball. The multi-piece solid golf ball according to any one of claims 1 to 7, wherein the intermediate layer has a Shore D hardness of 10 to 29.

Images