JP4866309B2 - Golf ball - Google Patents

Description

  The present invention relates to a one-piece golf ball, and more particularly to a technique for improving the resilience and durability of a rubber composition used for a one-piece golf ball.

  A one-piece golf ball consisting of one layer is usually a spherical molded body of a rubber composition containing a base rubber, a co-crosslinking agent, and a crosslinking agent. Golf ball characteristics such as resilience and durability are greatly influenced by the rubber composition constituting the one-piece golf ball. For example, by increasing the resilience of the golf ball, a longer flight distance can be obtained at the time of hitting, and if the durability is increased, the golf ball can be prevented from cracking even when used repeatedly. Since the one-piece golf ball is composed of a 100% rubber composition, the rubber composition, particularly the base rubber contained in the rubber composition, has a greater influence than multi-layer golf balls such as two-piece golf balls and three-piece golf balls. Therefore, for example, in order to improve the golf ball characteristics, improvement of the base rubber contained in the rubber composition has been studied.

For example, Patent Document 1 discloses a cis-1,4-synthesized using a metallocene catalyst of a rare earth metal compound and a catalyst comprising a composition containing an ionic compound comprising a non-coordinating anion and a cation and / or an aluminoxane. Polybutadiene with 99% or more bonds is disclosed. Patent Document 2 discloses a cis-1,4-bond 80 synthesized using a metallocene catalyst of a rare earth metal compound and a catalyst comprising a composition comprising an ionic compound comprising a non-coordinating anion and a cation and / or an aluminoxane. % Of polybutadiene having a molecular weight distribution (Mw / Mn) of 1.2 to 2.0 is disclosed. Patent Document 3 discloses a one-piece golf ball made of a rubber composition containing two types of polybutadienes having a specific molecular weight in a specific compounding ratio.
JP 2002-282393 A JP 2002-338737 A JP 2002-35167 A

  However, the technique of increasing the content of cis-1,4-bond using a metallocene catalyst as described above is not suitable industrially because the metallocene catalyst is unstable in the air. There is. In addition, by simply adjusting the molecular weight of the polydiene rubber, the resilience and flight distance performance of the golf ball are not satisfactory, and there is still room for improvement. Furthermore, polybutadiene has bonding modes such as trans-1,4-bond and 1,2-vinyl bond in addition to cis-1,4-bond. It is known that when the bond content is high, the resilience decreases.

  The present invention has been made in view of the above circumstances, and in a one-piece golf ball using a rubber composition containing a polydiene having a high content of cis-1,4-bond as a base rubber, It aims at improving the resilience and durability of the obtained one-piece golf ball by lowering the content of, 4-bond.

The one-piece golf ball of the present invention that has solved the above problems is
(A) a base rubber containing a polydiene obtained by polymerizing a diene in the presence of a catalyst containing a salen metal complex and an aluminoxane;
(B) a co-crosslinking agent, and
(C) It is characterized by being formed by molding a rubber composition containing a crosslinking agent.

  That is, the gist of the present invention is that a polydiene obtained by polymerizing a diene in the presence of a catalyst containing a salen type metal complex and an aluminoxane is used as a base rubber of a rubber composition constituting a one-piece golf ball. . By polymerizing a diene in the presence of a catalyst containing a salen-type metal complex and an aluminoxane, the content of cis-1,4-bond in the resulting polydiene is increased to 90% or more, and a trans-1,4-bond is obtained. The content of can be 1% or less. As a result, by using such polydiene as a base rubber, the resilience and durability of the resulting one-piece golf ball is improved.

  Examples of the diene include 1,3-butadiene, 2-methyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. 2-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene and 2,4-hexadiene are preferable, and 1,3-butadiene is particularly preferable.

  Examples of the metal of the salen-type metal complex include nickel, cobalt, iron, titanium, vanadium, and the like. It is preferable to use a catalyst composed of a salen-type cobalt complex and methylaluminoxane as the catalyst. is there.

  According to the present invention, a one-piece golf ball having excellent resilience and durability can be obtained.

The one-piece golf ball of the present invention
(A) a base rubber containing a polydiene obtained by polymerizing a diene in the presence of a catalyst containing a salen metal complex and an aluminoxane;
(B) a co-crosslinking agent, and
(C) It is characterized by being formed by molding a rubber composition containing a crosslinking agent.

  First, (a) a base rubber containing a polydiene obtained by polymerizing a diene in the presence of a catalyst containing a salen type metal complex and an aluminoxane (hereinafter sometimes referred to as “high cis / low trans polydiene”) will be described. To do.

  The salen type metal complex is, for example, represented by the following chemical formula (1) or (2), and a salen ligand [N, N′-bis (salicylidene) ethylenediamine (N, N′-bis (salicylidene)]. ) Ethylenediamine)] or a derivative thereof and a metal.

In the formula, each of R ¹ , R ² , R ³ and R ⁴ may be the same or different, and is an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 4 carbon atoms) or a hydrogen atom thereof. Partially substituted with halogen or hydrogen. More preferably, R ¹ or both R ¹ and R ³ is an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 4 carbon atoms), and R ² and R ⁴ are Hydrogen. R ⁵ is an alkyl group having 1 to 10 carbon atoms or a group in which part of its hydrogen is substituted with halogen, a group in which a phenyl group or part of its hydrogen is substituted with halogen, or hydrogen, , two R ⁵ which are adjacent, may form a benzene ring or a cyclohexyl ring. M is a metal and X is an anion.

  The salen ligand is synthesized by a dehydration condensation reaction of a corresponding salicylaldehyde and ethylenediamine derivative.

  Examples of the corresponding salicylaldehyde include salicylaldehyde, 2-hydroxy-3,5-dimethylbenzaldehyde, 2-hydroxy-5-methylbenzaldehyde, 5-tert-butyl-2-hydroxybenzaldehyde, 3,5-di- Examples include tert-butyl-2-hydroxybenzaldehyde. Examples of ethylenediamine derivatives include 1,2-ethanediamine (ethylenediamine); 1,2-benzenediamine; (1R, 2S) -1,2-cyclohexanediamine, (1S, 2S) -1,2-cyclohexanediamine. 1,2-cyclohexanediamine such as (1R, 2R) -1,2-cyclohexanediamine or trans-1,2-cyclohexanediamine.

  The metal of the salen type metal complex is not particularly limited, and examples thereof include nickel, cobalt, iron, titanium, vanadium, and particularly preferably cobalt.

Examples of the anion X of the salen type metal complex include hydroxide ions (OH ⁻ ); haloniums such as chloride ions (Cl ⁻ ), bromide ions (Br ⁻ ), fluoride ions (F ⁻ ); acetic acid Ion (CH ₃ COO ⁻ ); nitrate ion (NO ₃ ⁻ ); sulfate ion (SO ₄ ²⁻ ), oxalate ion (C ₂ O ₄ ²⁻ ); phosphate ion (PO ₄ ⁻ ), hexafluorophosphate ion An anion such as (PF ₆ ⁻ ) can be mentioned. In the present invention, as represented by the formula (2), a salen type metal complex in which the anion X does not exist can also be used.

  As the salen type metal complex, N, N′-bis (3-tert-butylsalicylidene) ethylenediaminatocobalt (II) [N, N′-bis (3-tert-butylsalicylidene) is particularly preferable. ethylenediamine Cobalt (II)] (formula (3)), N, N′-bis (3-tert-butyl-5-methylsalicylidene) ethylenediaminatocobalt (II) [N, N′-bis (3) -Tert-butyl-5-methylsalicylidene) ethylenediaminato Cobalt (II)] (formula (4)), N, N'-bis (3,5-di-tert-butylsalicylidene) ethylenediaminatocobalt (II) [N, N′-bis (3,5-di-ter -Butylsalicylidene) ethylenediaminato Cobalt (II)] (formula (5)), N, N'-bis (3,5-di-tert-butylsalicylidene) 1,2-diphenylethylenediaminatocobalt (II) [ N, N′-bis (3,5-di-tert-butylsalicylidene) 1,2-diphenylethylenediamine Cobalt (II)] (formula (6)) and the like.

  As the aluminoxane, for example, those obtained by bringing an organoaluminum compound (preferably trimethylaluminum) into contact with a condensing agent (preferably water) can be used. More specifically, the following formula (7) can be used. It has the structure represented by these.

  In the formula, R is a hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 4 carbon atoms), and may be the same or different in adjacent structural units, preferably the same. The hydrocarbon group may be substituted with a halogen atom and / or an alkoxy group. n represents a polymerization degree and is an integer of 4 to 20. Examples of R include a methyl group, an ethyl group, a propyl group, and an isobutyl group, and a methyl group is preferable. Examples of the organoaluminum compound used as the starting material for the aluminoxane include trialkylaluminums such as trimethylaluminum, triethylaluminum, and tributylaluminum, or a mixture thereof, and trimethylaluminum is preferable. An aluminoxane made from a mixture of trimethylaluminum and tributylaluminum can also be used. In the present invention, it is particularly preferable to use methylaluminoxane in which R in all structural units is a methyl group in the formula (7).

The high-cis / low-trans polydiene used in the present invention is not particularly limited as long as it is obtained by polymerization in the presence of the above-described catalyst containing a salen-type metal complex and an aluminoxane. Aluminum chloride (Et ₂ AlCl) or the like can be included. Moreover, it is also a preferable aspect to use the catalyst which consists only of the salen type metal complex mentioned above and an aluminoxane.

  Examples of the diene used in the present invention include 1,3-butadiene, 2-methyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 1,3. -Conjugated dienes such as pentadiene, 2-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexanediene, 2,4-hexadiene, Butadiene is particularly preferred.

  Incidentally, polyhexadiene produced by polymerizing 2,4-hexadiene produces cis-2,5-bond and trans-2,5-bond. The bonds and trans-2,5-links are considered to be cis-1,4-bonds and trans-1,4-bonds, respectively. The content rate shall be calculated. In addition, for diene having 6 or more carbon atoms, the content of cis-1,4-bond and trans-1,4-bond is calculated by the same method.

  The method for polymerizing the diene in the presence of a catalyst containing a salen-type metal complex and an aluminoxane is not particularly limited, and the polymerization temperature is, for example, 0 ° C. or higher, preferably 10 ° C. or higher. A temperature of less than or equal to 0, preferably less than or equal to 80 ° C is desirable. The polymerization time is 0.5 hours or longer, preferably 1 hour or longer, 12 hours or shorter, preferably 6 hours or shorter.

  The amount of the salen metal complex and the aluminoxane used is not particularly limited, but the salen metal complex is 0.01 parts by mass or more, preferably 0.05 parts by mass or more, and 2 parts by mass with respect to 100 parts by mass of the diene. Part or less, preferably 1 part by weight or less. The aluminoxane is preferably used in an amount of 1 part by mass or more, preferably 3 parts by mass or more and 40 parts by mass or less, preferably 30 parts by mass or less with respect to 100 parts by mass of the diene.

  The polymerization is preferably performed in a solvent that dissolves the diene, the salen-type metal complex, and the aluminoxane. Examples of the solvent include halogen-based solvents and non-halogen-based solvents, and it is preferable to use a halogen-based solvent in which the salen-type metal complex has high solubility.

  Examples of the halogen solvents include methylene chloride, dichloromethane, chloroform, chloroethane, bromopropane, bromobutane, iodomethylpropane, fluoromethylpropane, and other mono-, di-, or trihalogen substitutes of alkanes; chlorobenzene, dichlorobenzene, bromo Mention may be made of mono-, di-, or trihalogen-substituted products of benzene such as benzene, tribromobenzene and iodobenzene. Among these, methylene chloride, dichloromethane, and chloroform are preferable.

  Examples of the non-halogen solvents include aromatic solvents such as benzene, toluene and nitrobenzene, aliphatic hydrocarbon solvents such as pentane, hexane, heptane and octane, dimethylformamide (DMF), dimethylacetamide (DMA) and the like. Is mentioned.

  In addition, the catalytic activity can be enhanced by controlling the order of addition of the salen metal complex, aluminoxane, and diene according to the type of metal of the salen metal complex. For example, when a salen-type cobalt complex is used, it is a preferred embodiment that the salen-type cobalt complex is added to the diene and then activated with an aluminoxane. The rate can be increased. In addition, in the salen type nickel complex, the influence by the addition order is hardly recognized.

  The cis-1,4-bond content of the high cis / low trans polydiene used in the present invention is 90% or more, more preferably 96% or more, still more preferably 98% or more, and even more preferably 99% or more. It is desirable. Further, the trans-1,4-bond content of the polydiene is 1% or less, more preferably 0.8% or less, still more preferably 0.5% or less, and still more preferably 0.3% or less. . By increasing the content of cis-1,4-bond and decreasing the content of trans-1,4-bond, a golf ball having excellent resilience and durability can be obtained. Therefore, the content of the trans-1,4-bond in the polydiene is most preferably 0%.

In addition to the cis-1,4-bond and the trans-1,4-bond, the polydiene has a 1,2-vinyl bond in addition to a high content of cis-1,4-bond. Even if it becomes, the content of the trans-1,4-bond does not decrease directly. The present invention is characterized in that a polydiene having a high cis-1,4-bond content and a low trans-1,4-bond content is used. The content of trans-1,4-bond, cis-1,4-bond, and 1,2-vinyl bond can be calculated by using ¹ H-NMR and ¹³ C-NMR.

The cis-1,4-bond, trans-1,4-bond, and 1,2-vinyl bond are defined as follows in the polydiene represented by the following formula (8), for example.
Cis-1,4-bond (%) = 100 × X / (X + Y + Z)
Trans-1,4-bond (%) = 100 × Y / (X + Y + Z)
1,2-vinyl bond (%) = 100 × Z / (X + Y + Z)

（式中、Ｘ，Ｙ，Ｚは、それぞれの構成単位のユニット数を示す）

(In the formula, X, Y and Z represent the number of units of each constituent unit)

  The rubber composition used in the present invention can contain other rubber components as a base rubber in addition to the above-mentioned high-cis / low-trans polydiene as long as the effects of the present invention are not impaired. Examples of the other rubber components include polybutadiene, ethylene / propylene / diene terpolymer (EPDM), isoprene rubber (IR), butyl rubber (IIR), natural rubber (NR), nitrile rubber (NBR), and styrene. One type or two or more types such as rubber (SBR) can be mentioned. Among these, it is particularly preferable to use high-cis polybutadiene having a cis-1,4-bond advantageous for resilience of 70% or more, more preferably 90% or more, and still more preferably 96% or more.

  The content of the high cis / low trans polybutadiene in the base rubber is preferably 50% or more, more preferably 60% or more, and still more preferably 70% or more. It is also a preferred embodiment that substantially only the high-cis / low-trans polydiene is used as the base rubber.

  The (b) co-crosslinking agent contained in the rubber composition used in the present invention is not particularly limited as long as it has a function of cross-linking rubber molecules by graft polymerization to rubber molecular chains. For example, α, Mention may be made of β-unsaturated carboxylic acids and / or their metal salts. Examples of the metal constituting the metal salt include monovalent or divalent metals such as zinc, magnesium, calcium, or sodium, and zinc or magnesium is more preferable. Examples of the α, β-unsaturated carboxylic acid and / or metal salt thereof include, for example, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof, and more preferably acrylic. Examples thereof include acid, methacrylic acid, zinc acrylate, and zinc methacrylate. Moreover, it is also a preferable aspect to use polyfunctional (meth) acrylic acid esters such as trimethylolpropane tri (meth) acrylate as the co-crosslinking agent.

  The content of the (b) co-crosslinking agent in the rubber composition is preferably 15 parts by mass or more, more preferably 18 parts by mass or more, and further preferably 22 with respect to 100 parts by mass of the base rubber. More than part by mass. By setting it as 18 mass parts or more, the hardness of the molded object obtained by shape | molding a rubber composition can be made moderate. This is because if the molded body becomes too soft, the amount of deformation at the time of hitting ball becomes large, and the hit feeling may be lowered. Further, the content of the (b) co-crosslinking agent in the rubber composition is preferably 45 parts by mass or less, more preferably 38 parts by mass or less, further preferably 100 parts by mass of the base rubber. Is 30 parts by mass or less. By setting it to 45 parts by mass or less, a suitable shot feeling can be obtained.

  The (c) crosslinking agent contained in the rubber composition used in the present invention is blended for crosslinking the base rubber component. As the crosslinking agent, an organic peroxide is preferably used. For example, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,5-trimethylcyclohexane, 2,5-dimethyl-2,5 -Di (t-butylperoxy) hexane, di-t-butyl peroxide, etc. are mentioned, and it is preferable to use dicumyl peroxide. The crosslinking agent is blended in an amount of 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and 5 parts by mass or less, more preferably 3 parts by mass or less with respect to 100 parts by mass of the base rubber. Is desirable.

  The rubber composition used in the present invention may contain an organic sulfur compound in addition to the above components. The content of the organic sulfur compound is preferably 0.05 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 5.0 parts by mass or less with respect to 100 parts by mass of the base rubber. More preferably, it is 3.0 parts by mass or less.

  As the organic sulfur compound, diphenyl disulfides are preferably used. For example, diphenyl disulfide, bis (4-chlorophenyl) disulfide, bis (3-chlorophenyl) disulfide, bis (4-bromophenyl) disulfide, bis (3-bromo Monosubstituted compounds such as phenyl) disulfide, bis (4-fluorophenyl) disulfide, bis (4-iodophenyl) disulfide, bis (4-cyanophenyl) disulfide; bis (2,5-dichlorophenyl) disulfide, bis (3, 5-dichlorophenyl) disulfide, bis (2,6-dichlorophenyl) disulfide, bis (2,5-dibromophenyl) disulfide, bis (3,5-dibromophenyl) disulfide, bis (2-chloro-5-bromophenyl) Disubstituted compounds such as disulfide and bis (2-cyano-5-bromophenyl) disulfide; bis (2,4,6-trichlorophenyl) disulfide, bis (2-cyano-4-chloro-6-bromophenyl) disulfide and the like A tri-substituted product of bis (2,3,5,6-tetrachlorophenyl) disulfide; a bis (2,3,4,5,6-pentachlorophenyl) disulfide, bis (2,3,4,4) And penta-substituted compounds such as 5,6-pentabromophenyl) disulfide. These diphenyl disulfides have some influence on the vulcanized state of the rubber molded body, and can improve the resilience. Among these, it is preferable to use diphenyl disulfide and bis (pentabromophenyl) disulfide from the viewpoint that a highly repulsive golf ball can be obtained.

  The rubber composition used in the present invention includes, in addition to the base rubber, co-crosslinking agent and crosslinking agent, a pigment; a filler for adjusting specific gravity; an antioxidant, an anti-aging agent, a peptizer, And you may contain additives, such as a softener.

  Examples of the pigment blended in the rubber composition include a white pigment, a blue pigment, and a purple pigment. As the white pigment, titanium oxide is preferably used. The type of titanium oxide is not particularly limited, but it is preferable to use a rutile type because it has good concealability. Further, the content of titanium oxide is 0.5 parts by mass or more, more preferably 2 parts by mass or more, and preferably 8 parts by mass or less, more preferably 5 parts by mass or less, with respect to 100 parts by mass of the base rubber. It is desirable to be.

  It is also a preferred embodiment that the rubber composition contains a white pigment and a blue pigment. The blue pigment is blended to make white appear vivid, and examples thereof include ultramarine blue, cobalt blue, and phthalocyanine blue. Examples of the purple pigment include anthraquinone violet, dioxazine violet, and methyl violet.

  The amount of the blue pigment used is 0.001 part by mass or more, more preferably 0.05 part by mass or more and 0.2 part by mass or less, more preferably 0.001 part by mass or more with respect to 100 parts by mass of the base rubber. The amount is desirably 1 part by mass or less. When the amount is less than 0.001 part by mass, the bluish color is insufficient and the color looks yellowish. When the amount exceeds 0.2 part by mass, the color becomes too blue and a bright white appearance is lost.

  The filler blended in the rubber composition is blended mainly as a specific gravity adjusting agent for adjusting the specific gravity of the one-piece golf ball obtained as a final product to a range of 1.0 to 1.5. This can be blended. As the filler, any filler that is usually blended in one-piece golf balls may be used. For example, inorganic fillers (specifically, zinc oxide, barium sulfate, calcium carbonate), high specific gravity metal powder (for example, tungsten powder, Molybdenum powder and the like) and mixtures thereof. Particularly preferred is zinc oxide that also functions as a vulcanization aid. When zinc oxide is used, the blending amount is 30 parts by weight or less, preferably 25 parts by weight or less, more preferably 15 parts by weight or less, with respect to 100 parts by weight of the base rubber. Decreases, and high resilience cannot be obtained.

  The blending amount of the anti-aging agent blended in the rubber composition is preferably 0.1 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the base rubber. Moreover, it is preferable that a peptizer is 0.1 to 5 mass parts with respect to 100 mass parts of base rubber.

  The one-piece golf ball of the present invention is formed by molding the rubber composition described above. The conditions for molding the rubber composition into a spherical molded body may be appropriately set according to the rubber composition. Usually, the rubber composition is heated at 130 to 200 ° C. for 10 to 60 minutes, or 130 to After heating at 150 ° C. for 20 to 40 minutes, it is preferable to heat at 160 to 180 ° C. in 5 to 15 minutes.

  The diameter of the one-piece golf ball of the present invention is 42.67 mm or more, preferably 42.67 mm or more and 42.82 mm or less, and has a mass of 45.93 g or less, preferably 44.0 g or more and 45.45 mm, based on the golf ball rules. It is formed to 8 g or less.

  When the one-piece golf ball of the present invention has a diameter of 42.67 mm to 42.82 mm, the amount of compressive deformation (the amount by which the golf ball shrinks in the compression direction) from when the initial load is 98 N to when the final load is 1275 N is applied. 2.3 mm or more, more preferably 2.4 mm or more, further preferably 2.5 mm or more, 3.0 mm or less, more preferably 2.8 mm or less, and further preferably 2.7 mm or less. It is desirable. When the amount of compressive deformation is less than 2.3 mm, the feel at impact is hard and worse, and when it exceeds 3.0 mm, durability may be reduced.

  In a preferred embodiment of the one-piece golf ball of the present invention, the surface hardness is larger than the center hardness. The difference in hardness between the surface hardness and the center hardness of the one-piece golf ball of the present invention is preferably 15 or more and more preferably 18 or more in Shore D hardness. By making the surface hardness of the one-piece golf ball larger than the center hardness, the launch angle is increased, the spin rate is decreased, and the flight distance is improved. The upper limit of the Shore D hardness difference between the surface hardness and the center hardness of the one-piece golf ball is not particularly limited, but is preferably 30 and more preferably 25. This is because if the hardness difference becomes too large, the durability may be lowered.

  Furthermore, the center hardness of the one-piece golf ball of the present invention is preferably 25 or more in Shore D hardness, more preferably 30 or more, and further preferably 32 or more. When the center hardness is less than 25 in Shore D hardness, durability of the resulting one-piece golf ball may be lowered. The central hardness is preferably 45 or less, more preferably 42 or less, even more preferably 40 or less in Shore D hardness. This is because if the center hardness exceeds 45 in Shore D hardness, the hardness becomes too hard and the shot feeling tends to decrease. In the present invention, the center hardness of a one-piece golf ball means the hardness measured by cutting the golf ball into two equal parts and measuring the center point of the cut surface with a spring type hardness meter Shore D type.

  The surface hardness of the one-piece golf ball of the present invention is preferably 45 or more in Shore D hardness, more preferably 50 or more, and further preferably 52 or more. If the surface hardness is less than 45, the surface hardness may be too soft and the resilience may be reduced. The surface hardness is preferably 70 or less in Shore D hardness, more preferably 65 or less, and still more preferably 60 or less. This is because if the surface hardness is more than 70 in Shore D hardness, the durability of the resulting golf ball may be lowered.

  Next, a method for producing the golf ball of the present invention will be described, but the present invention is not limited to such a production method. First, (a) a base rubber, (b) a co-crosslinking agent, (c) a cross-linking agent, and further, if necessary, a filler, an additive and the like are blended and kneaded to prepare a rubber composition. The obtained rubber composition is usually heated at 130 to 200 ° C. for 10 to 60 minutes to form a spherical molded body. When there is no difference in hardness between the surface hardness and the center hardness of the one-piece golf ball, for example, after heating at 130 to 150 ° C. for 20 to 40 minutes, heating at 160 to 180 ° C. for 5 to 15 minutes And it shape | molds in a spherical molded object. In the molded body, a depression called dimple is usually formed on the surface. Further, the surface of the one-piece golf ball main body may be subjected to a polishing treatment such as a sand blasting treatment in order to further improve the adhesion with the coating film.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments without departing from the gist of the present invention are not limited thereto. Included in range.

[Evaluation methods]
(1) Coefficient of restitution Each one-piece golf ball was impacted with 198.4 g of a metal cylinder at a speed of 40 m / second, and the speeds of the cylinder and the one-piece golf ball before and after the collision were measured. The coefficient of restitution of each golf ball was calculated. The measurement was performed 12 pieces for each one-piece golf ball, and the average value was used as the coefficient of restitution of each one-piece golf ball.

(2) Flight distance A metal head wood club No. 1 (SIO Sports Co., Ltd., XXIO, loft angle 10 °) is attached to a Truetemper swing robot, and each golf ball is hit with a head speed of 45 m / sec. Then, the flight distance (carry) to the drop point was measured. The measurement was performed 12 pieces for each golf ball, and the average value was taken as the result of each golf ball. Note that the flight distance is golf ball no. The flying distance of 4 is taken as 100, and is shown as an indexed value.

(3) Cracking durability A metal head wood club No. 1 (XXIO, SRI Sports Co., Ltd., loft angle 10 °) was attached to a swing robot manufactured by Trutemper, and each golf ball was hit at a head speed of 45 m / sec. The number of hits until the golf ball was broken by colliding with the collision plate was measured. The cracking durability of each golf ball is determined according to the golf ball no. The number of hits of 4 is assumed to be 100, and the number of hits for each golf ball is shown as an index. A larger indexed value indicates that the golf ball is more excellent in cracking durability.

(4) Compression deformation (mm)
The amount of deformation in the compression direction (the amount of contraction in the compression direction) from when the one-piece golf ball was loaded with an initial load of 98 N to when the final load of 1275 N was loaded was measured.

(5) Quantification method of cis, trans, vinyl bond in polydiene The ratio of 1,2-vinyl bond and (cis-1,4-bond + trans-1,4-bond) was determined using ¹ H-NMR. (See FIG. 1). That is, in the ¹ H-NMR chart obtained by measurement, the peaks around about 5.0 ppm and about 5.4 ppm are respectively the peak of 1,2-vinyl bond and (cis-1,4-bond + trans- 1,4-bond) peak. The ratio of 1,2-vinyl bond and (cis-1,4-bond + trans-1,4-bond) is proportional to the area ratio of these peaks, so that the ratio is easily calculated. be able to.

Further, the ratio of cis-1,4-bond and trans-1,4-bond can be determined using ¹³ C-NMR (see FIG. 2). That is, in ¹³ C-NMR obtained by measurement, the peak at 27 to 28 ppm and the peak near 33 ppm can be attributed to cis-1,4-bond and trans-1,4-bond, respectively. Since the ratio of 1,4-bond and trans-1,4-bond is proportional to the ratio of these peak areas, the ratio can be easily calculated.

  In this invention, it measured using JEOL Co., Ltd. JOEL alpha-400NMR.

[Production of salen-type metal complexes]
Salen metal complex 1
15 g (0.064 mol) of 3,5-di-tert-butylsalicylaldehyde (0.05-mol) was dissolved in 500 ml of methanol, and 1.92 g (0.032 mol) of ethylenediamine was added to room temperature. For 2 hours. The obtained reaction product was filtered, and 13.3 g (0.0266 mol) of N, N′-bis (3,5-di-tert-butylsalicylidene) ethylenediamine [N, N′-bis (3, 5-di-tert-butylsalicylidene) ethylenediamine] was obtained. Next, 8.753 g (0.0266 mol) of Co (OAc) ₂ .4H ₂ O was added to a solution obtained by dissolving this in 1000 g of methanol (MeOH), and the resulting product was refluxed for 2 hours. And the salen-type metal complex 1 (N, N′-bis (3,5-di-tert-butylsalicylidene) ethylenediaminatocobalt (II) [N, N′-bis (3,5 -Di-tert-butylsalicylidene) ethyldiaminato cobalt (II)]). The yield was 70%.

Salen metal complex 2
Instead of 15 g (0.064 mol) of 3,5-di-tert-butylsalicylaldehyde (3,5-di-tert-butylsalicylaldehyde) 11.4 g of 3-tert-butylsalicylaldehyde (3-tert-butylsalicylaldehyde) (0.064 mol) Except for using 0.064 mol), the salen-type metal complex 2 (N, N′-bis (3-tert-butylsalicylidene) ethylenediaminatocobalt (II) was prepared in the same manner as the salen-type metal complex 1. ) [N, N′-bis (3-tert-butylsalicylidene) ethyldiaminato cobalt (II)]). The yield was 45%.

Salen metal complex 3
In the same manner as Salen type metal complex 1, except for using 1.79 g (0.032 mol) of 1,2-diphenylethylenediamine instead of 1.92 g (0.032 mol) of ethylenediamine, Salen type metal complex 3 ( N, N′-bis (3,5-di-tert-butylsalicylidene) 1,2-diphenylethylenediaminatocobalt (II) [N, N′-bis (3,5-di-tert-butylsalicylidene ) 1,2-diphenylethylenediamine amine (II)]). The yield was 60%.

[Production of polybutadiene using metallocene catalyst]
The inside of the autoclave having an internal volume of 2 L was purged with nitrogen, 2.5 mmol of bispentamethylcyclopentadienylbistetrahydrofuran samarium was charged, and dissolved in 1.5 L of toluene. Subsequently, Modified MAO (toluene-soluble aluminoxane commercially available from Tosoh Akzo Co., Ltd.) was added so as to have an Al / Sm = 200 element ratio. Thereafter, 400 mL of 1,3-butadiene was charged, and polymerization was performed at 50 ° C. for 5 minutes. After the polymerization, 2.5 liters of methanol containing 10% by weight of 2,6-bis (t-butyl) -4-methylphenol was added to stop the reaction, and the polymer was separated with a large amount of methanol / hydrochloric acid mixed solvent. And dried in vacuum at 60 ° C. The yield of the obtained polybutadiene (hereinafter sometimes referred to as “metallocene catalyst BR”) was 65% by mass, and the results of measuring the content of each bond are shown in Table 1.

[Preparation of high-cis / low-trans polybutadiene]
The inside of the autoclave having an internal volume of 2 liters was purged with nitrogen, and 1200 ml of methylene chloride was put therein, 150 ml of 1,3-butadiene was charged therein, and the salen-type cobalt complex and methylaluminoxane (MAO: Tosoh Akzo, FW = 58.02) was added in this order so that the molar ratio of aluminum to cobalt was MAO / Co = 500, and polymerization was performed at room temperature. The charging ratio of 1,3-butadiene, salen type metal complex and methylaluminoxane was 1,3-butadiene: salen type metal complex: methylaluminoxane = 100: 0.0558: 27.9 (molar ratio). After the polymerization, 2 liters of methanol containing 10% by mass of BHT was added to stop the reaction, and the polymer obtained with a large amount of methanol / hydrochloric acid mixed solvent was separated and dried at 60 ° C. under vacuum. Table 1 shows the results of measuring the content of each bond between the obtained high-cis / low-trans polybutadiene and commercially available high-cis polybutadiene.

  As is apparent from the results in Table 1, polybutadiene (high cis / low trans polybutadiene) obtained by polymerizing 1,3-butadiene in the presence of a catalyst containing a salen type metal complex and methylaluminoxane is commercially available high cis. It can be seen that the content of trans-1,4 bonds is lower than that of polybutadiene.

[Production of one-piece golf balls]
A rubber composition having the composition shown in Table 2 was kneaded with a kneading roll and heated and pressed at 170 ° C. for 17 minutes in an upper and lower mold having hemispherical cavities to obtain a one-piece golf ball body. After the surface of the obtained one-piece golf ball body is sandblasted and marked, a clear paint is applied and the paint is dried in an oven at 40 ° C. to obtain a golf ball having a diameter of 42.8 mm and a mass of 45.4 g. Obtained. Table 2 shows the results of evaluating the amount of compression deformation, the coefficient of restitution, the flight distance, and the durability of the obtained one-piece golf ball.

BR11, BR730: JSR polybutadiene rubber (cis content 96% or more)
Methacrylic acid: Mitsubishi Rayon Co., Ltd. Zinc methacrylate oxide: Toho Zinc Co., Ltd.
Dicumyl peroxide: Park Mill D made by NOF
Diphenyl disulfide: manufactured by Sumitomo Seika

  As is apparent from Table 2, the one-piece golf ball No. 1 of the present invention using high-cis / low-trans polybutadiene is used. 1-No. 5 shows that it is excellent in resilience (flight distance) and durability. Further, it has been clarified that the one-piece golf ball of the present invention has excellent resilience and durability as compared with high-cis polybutadiene synthesized using a metallocene catalyst.

  The present invention is suitable for a one-piece golf ball.

¹ H-NMR chart of an example of polybutadiene. The ¹³ C-NMR chart of an example of polybutadiene.

Claims (7)

(A) It is obtained by polymerizing a diene in the presence of a catalyst containing a salen-type metal complex and an aluminoxane. The content of cis-1,4-bond is 98% or more, and the content of trans-1,4-bond is A base rubber containing polydiene that is 1% or less ,
(B) a co-crosslinking agent, and
(C) A one-piece golf ball formed by molding a rubber composition containing a crosslinking agent. The one-piece golf ball according to claim 1 , wherein a content of the trans-1,4-bond is 0.5% or less. The dienes are 1,3-butadiene, 2-methyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2- The one-piece golf ball according to claim 1 or 2 , which is a diene selected from the group consisting of methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 2,4-hexadiene. The diene is 1,3-butadiene, wherein the polydiene piece golf ball according to claim 1 or 2 is polybutadiene. The metal of the salen-type metal complex, nickel, cobalt, iron, titanium, one-piece golf ball according to any one of claims 1 to 4, at least one selected from the group consisting of vanadium. Wherein said catalyst is a one-piece golf ball according to any one of claims 1 to 5, made of a salen-type cobalt complex and methyl aluminoxane. The rubber composition contains (b) 15 parts by weight to 45 parts by weight of a co-crosslinking agent and (c) 0.2 parts by weight to 5 parts by weight of a crosslinking agent with respect to 100 parts by weight of the base rubber. The one-piece golf ball according to any one of claims 1 to 6 .

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