JP7023862B2 - Rubber composition and golf ball - Google Patents

Description

The present invention relates to rubber compositions and golf balls.

Generally, in the core of a one-piece golf ball and a multi-piece golf ball such as a two-piece golf ball and a three-piece golf ball, an α, β-unsaturated carboxylic acid is used as a base rubber containing butadiene rubber as a main component as a rubber component. A sulfide molded product of a rubber composition containing a metal salt and an organic peroxide is used. The metal salt of α, β-unsaturated carboxylic acid acts as a co-crosslinking agent and is introduced into the main chain of butadiene rubber to form a complicated three-dimensional crosslinked structure, so that the obtained vulcanized molded product has an appropriate hardness. And durability, as a result, solid golf balls using this vulcanized molded product show durability and resilience performance.

However, in this rubber composition, it is difficult to sufficiently disperse the metal salt of α, β-unsaturated carboxylic acid, so that the repulsion performance expected for the obtained golf ball cannot be imparted.

A large number of various rubber compositions have been proposed in order to improve the resilience performance of golf balls, and the main ones are (1) rubber compositions containing an anthranilic acid derivative (for example, Patent Document 1), (2). ) A rubber composition containing a fluorine-substituted phenyl sulfide compound (for example, Patent Document 2), (3) A rubber composition using a modified butadiene rubber having an active terminal modified with an alkoxysilane compound (for example, Patent Document 3 and). 4) and the like. However, the repulsive performance of golf balls produced from these rubber compositions is not satisfactory for users, and the development of rubber compositions capable of further improving the flight distance of golf balls is eagerly desired.

Japanese Unexamined Patent Publication No. 2013-108078 Japanese Unexamined Patent Publication No. 2002-338748 Japanese Unexamined Patent Publication No. 2009-119256 Japanese Unexamined Patent Publication No. 2008-161345

A main object of the present invention is to provide a rubber composition capable of imparting high resilience to a golf ball.

One of the other objects of the present invention is to provide a golf ball having excellent high resilience.

As a result of diligent studies to solve the above problems, the present inventors have discovered that a rubber composition can be imparted with high resilience by blending a specific tetrazine-based compound into the rubber composition. The present inventors have completed the present invention as a result of further studies based on such findings.

That is, the present invention provides the rubber composition and the golf ball shown below.
Item 1.
A rubber composition containing a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof, a cross-linking agent, and a co-cross-linking agent.
General formula (1):

[In the formula, X ¹ and X ² represent a hydrogen atom, an alkyl group, an aralkylthio group, an aralkyl group, an aryl group, an arylthio group, a heterocyclic group, or an amino group, which are the same or different. Each of these groups may have one or more substituents. ]
Item 2.
Item 2. The rubber composition according to Item 1, wherein the tetrazine compound is a tetrazine compound in which X ¹ and X ² represent a heterocyclic group in the general formula (1).
Item 3.
A rubber composition containing a modified polymer obtained by treating a tetrazine compound represented by the general formula (1) or a salt thereof, a cross-linking agent, and a co-cross-linking agent in a rubber component.
Item 4.
Item 2. The rubber composition according to Item 1 or 2, which contains 0.1 to 10 parts by mass of a tetrazine compound represented by the general formula (1) or a salt thereof with respect to 100 parts by mass of the rubber component.
Item 5.
Item 3. The rubber according to Item 3, wherein the modified polymer is a modified polymer obtained by treating 100 parts by mass of a rubber component with 0.1 to 10 parts by mass of a tetrazine compound represented by the general formula (1) or a salt thereof. Composition.
Item 6.
Item 6. The rubber composition according to any one of Items 1 to 5, which contains 0.1 to 10 parts by mass of a cross-linking agent and 5 to 60 parts by mass of a co-crosslinking agent with respect to 100 parts by mass of the rubber component.
Item 7.
Item 6. The rubber composition according to any one of Items 1 to 6, wherein the diene-based rubber is 50 parts by mass or more in 100 parts by mass of the rubber component.
Item 8.
Item 6. The rubber composition according to Item 7, wherein the diene-based rubber contains a butadiene rubber.
Item 9.
Item 2. The rubber composition according to Item 1, 2, 3 or 6, wherein the cross-linking agent is an organic peroxide.
Item 10.
Item 6. The rubber composition according to Item 1, 2, 3 or 6, wherein the co-crosslinking agent is a metal salt of α, β-unsaturated carboxylic acid.
Item 11.
Item 6. The rubber composition according to any one of Items 1 to 10, further comprising an inorganic filler.
Item 12.
Item 2. The rubber composition according to Item 11, which contains 5 to 130 parts by mass of an inorganic filler with respect to 100 parts by mass of the rubber component.
Item 13.
Item 2. The rubber composition according to Item 11 or 12, wherein the inorganic filler is zinc oxide.
Item 14.
Item 6. The rubber composition according to any one of Items 1 to 13, which is used for a core of a golf ball.
Item 15.
A modified polymer obtained by treating 100 parts by mass of a rubber component with 0.1 to 10 parts by mass of a tetrazine compound represented by the general formula (1) or a salt thereof.
Item 16.
A golf ball core produced by using the rubber composition according to any one of Items 1 to 14.
Item 17.
Item 16. A golf ball containing the golf ball core according to Item 16.
Item 18.
A golf ball produced by using the rubber composition according to any one of Items 1 to 14.

Since the rubber composition of the present invention can sufficiently disperse the co-crosslinking agent, the vulcanized molded product can form a highly crosslinked structure, whereby high resilience can be exhibited.

The golf ball of the present invention is made of the rubber composition and has excellent high resilience.

Further, since the rubber composition of the present invention has excellent durability in addition to high resilience, it is possible to provide a golf ball having high resilience and excellent durability.

The details of the present invention will be described below.

1. 1. Rubber Composition The rubber composition of the present invention comprises a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof (hereinafter, also referred to as “tetrazine compound (1)”), a cross-linking agent, and a co-former. Contains a cross-linking agent.
General formula (1):

[In the formula, X ¹ and X ² represent a hydrogen atom, an alkyl group, an alkylthio group, an aralkyl group, an aryl group, an arylthio group, a heterocyclic group, or an amino group, which are the same or different. Each of these groups may have one or more substituents. ]

Further, the rubber composition of the present invention contains a modified polymer, a cross-linking agent and a co-cross-linking agent obtained by treating the rubber component and the tetrazine compound (1).

In the rubber composition of the present invention, the blending amount of the tetrazine compound (1) is usually 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is 0.5 to 2 parts by mass.

In the rubber composition of the present invention, the blending amount of the cross-linking agent is usually 0.1 to 10 parts by mass, preferably 0.2 to 7.5 parts by mass, based on 100 parts by mass of the rubber component. It is preferably 0.5 to 5 parts by mass. By setting the blending amount of the cross-linking agent in these ranges, the obtained rubber composition can be made to have an appropriate hardness, the resilience can be improved, and the durability can be improved.

In the rubber composition of the present invention, the blending amount of the co-crosslinking agent is usually 5 to 60 parts by mass, preferably 7.5 to 50 parts by mass, and more preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. It is ~ 45 parts by mass. By setting the blending amount of the co-crosslinking agent in these ranges, the obtained rubber composition can be made to have an appropriate hardness, the manufacturing workability can be improved, and the durability can be improved.

When both the cross-linking agent and the co-cross-linking agent are blended, the total amount of both components is usually 5 to 70 parts by mass, preferably 5.5 to 57.5 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it may be appropriately adjusted so as to be 10 to 50 parts by mass.

When blending the cross-linking agent and the co-cross-linking agent, a master batch previously mixed with the polymer may be used.

Further, an inorganic filler may be blended for the purpose of improving the strength of the crosslinked molded product of the rubber composition, or for the purpose of adjusting the weight and imparting the strength of the golf ball produced from the rubber composition.

In the rubber composition of the present invention, the blending amount of the inorganic filler is usually 5 to 130 parts by mass with respect to 100 parts by mass of the rubber component.

Rubber component The rubber component to be blended in the rubber composition of the present invention is not particularly limited, and is, for example, natural rubber (NR), synthetic diene-based rubber, a mixture of natural rubber and synthetic diene-based rubber, and other than these. Non-diene rubber can be mentioned.

Examples of natural rubber include natural rubber latex, technically rated rubber (TSR), smoked sheet (RSS), backlash, natural rubber derived from Tochu, natural rubber derived from Guayur, natural rubber derived from Russian dandelion, and the like. Modified natural rubber such as epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber is also included in the natural rubber of the present invention.

Synthetic diene rubbers include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), and ethylene-propylene-diene ternary products. Polymer rubber (EPDM), styrene-isoprene-styrene ternary block copolymer (SIS), styrene-butadiene-styrene ternary block copolymer (SBS), ethylene-α-olefin copolymer rubber (SPO), ethylene Examples thereof include -α-olefin-diene copolymer rubber and the like, and modified synthetic diene-based rubbers thereof. The modified synthetic diene-based rubber includes diene-based rubbers obtained by modification methods such as main chain modification, single-ended modification, and double-ended modification. Here, examples of the modified functional group of the modified synthetic diene rubber include various functional groups such as an epoxy group, an amino group, an alkoxysilyl group, and a hydroxyl group, and one or more of these functional groups are modified synthetic diene. It may be contained in the rubber.

The method for producing the synthetic diene rubber is not particularly limited, and examples thereof include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization. Further, the glass transition point of the synthetic diene rubber is not particularly limited.

Further, the ratio of cis / trans / vinyl in the double bond portion of the natural rubber and the synthetic diene rubber is not particularly limited, and any ratio can be suitably used. Further, the number average molecular weight and the molecular weight distribution of the diene rubber are not particularly limited. The diene rubber preferably has a number average molecular weight of 500 to 3000000 and a molecular weight distribution of 1.5 to 15.

The rubber component used in the rubber composition of the present invention preferably contains a diene-based rubber, and preferably contains 50 parts by mass or more of the diene-based rubber in 100 parts by mass of the rubber component, and 75 parts by mass or more. It is more preferable that it is contained, and it is particularly preferable that it is blended in a proportion of 80 to 100 parts by mass.

As the non-diene rubber, known rubbers can be widely used. The rubber component can be used alone or in combination of two or more. Among them, the preferable rubber component is at least one rubber component selected from the group consisting of natural rubber, IR, SBR, BR, and EPDM, or a mixture of two or more kinds, and more preferably BR. Further, when two or more kinds are mixed, the blending ratio thereof is not particularly limited.

Tetrazine compound (1)
The rubber composition of the present invention contains a tetrazine compound represented by the following general formula (1) or a salt thereof.
General formula (1):

[In the formula, X ¹ and X ² represent a hydrogen atom, an alkyl group, an alkylthio group, an aralkyl group, an aryl group, an arylthio group, a heterocyclic group, or an amino group, which are the same or different. Each of these groups may have one or more substituents. ]

In the present specification, the "alkyl group" is not particularly limited, and examples thereof include linear, branched or cyclic alkyl groups, and specific examples thereof include methyl group, ethyl group and n-propyl. Group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, 1-ethylpropyl group, n-pentyl group, neopentyl group, n-hexyl group, isohexyl group, 3-methylpentyl group Linear or branched alkyl group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms); cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, etc. Examples thereof include a cyclic alkyl group having 8 to 8 (particularly 3 to 6 carbon atoms). The preferred alkyl group is a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or n. -A pentyl group, particularly preferably a methyl group or an ethyl group.

In the present specification, the "alkylthio group" is not particularly limited, and examples thereof include linear, branched or cyclic alkylthio groups, and specifically, for example, methylthio group, ethylthio group and n-propylthio. Group, isopropylthio group, n-butylthio group, isobutylthio group, s-butylthio group, t-butylthio group, 1-ethylpropylthio group, n-pentylthio group, neopentylthio group, n-hexylthio group, isohexylthio A linear or branched alkylthio group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as a group and a 3-methylpentylthio group; a cyclopropylthio group, a cyclobutylthio group, a cyclopentylthio group and a cyclohexylthio. Examples thereof include a cyclic alkylthio group having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as a group, a cycloheptylthio group and a cyclooctylthio group. The preferred alkylthio group is a methylthio group, an ethylthio group, an isopropylthio group, or an isobutylthio group, and more preferably a methylthio group or an ethylthio group.

In the present specification, the "aralkyl group" is not particularly limited, and is, for example, a benzyl group, a phenethyl group, a trityl group, a 1-naphthylmethyl group, a 2- (1-naphthyl) ethyl group, and a 2- (2-naphthyl) group. ) Ethyl group and the like can be mentioned. The more preferable aralkyl group is a benzyl group or a phenethyl group, and more preferably a benzyl group.

In the present specification, the "aryl group" is not particularly limited, and examples thereof include a phenyl group, a biphenyl group, a naphthyl group, a dihydroindenyl group, and a 9H-fluorenyl group. The more preferable aryl group is a phenyl group or a naphthyl group, and more preferably a phenyl group.

In the present specification, the "arylthio group" is not particularly limited, and examples thereof include a phenylthio group, a biphenylthio group, and a naphthylthio group.

In the present specification, the "heterocyclic group" is not particularly limited, and for example, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazinyl group, 2-pyrimidyl group, 4-pyrimidyl group, and the like. 5-pyrimidyl group, 3-pyridadyl group, 4-pyridadyl group, 4- (1,2,3-triazyl) group, 5- (1,2,3-triazyl group), 2- (1,3,5- Triagil) group, 3- (1,2,4-triazil) group, 5- (1,2,4-triazil) group, 6- (1,2,4-triazil) group, 2-quinoline group, 3- Quinoline group, 4-quinoline group, 5-quinoline group, 6-quinoline group, 7-quinolyl group, 8-quinoline group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6- Isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group, 2-quinoxalyl group, 3-quinoxalyl group, 5-quinoxalyl group, 6-quinoxalyl group, 7-quinoxalyl group, 8-quinoxalyl group, 3-cinnolyl group, 4- Synoryl group, 5-Synolyl group, 6-Synolyl group, 7-Synolyl group, 8-Synolyl group, 2-Kinazolyl group, 4-Kinazolyl group, 5-Kinazolyl group, 6-Kinazolyl group, 7-Kinazolyl group, 8- Kinazolyl group, 1-phthalazyl group, 4-phthalazyl group, 5-phthalazyl group, 6-phthalazyl group, 7-phthalazyl group, 8-phthalazyl group, 1-tetrahydroquinoline group, 2-tetrahydroquinoline group, 3-tetrahydro Quinoline group, 4-Tetrahydroquinoline group, 5-Tetrahydroquinoline group, 6-Tetrahydroquinoline group, 7-Tetrahydroquinoline group, 8-Tetrahydroquinoline group, 1-Pyrrrolyl group, 2-Pyrrolyl group, 3 -Pyrrolyl group, 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-imidazolyl group, 2-imidazolyl group, 4-imidazolyl group, 5-imidazolyl group, 1-pyrazolyl group, 3 -Pyrazolyl group, 4-pyrazolyl group, 5-pyrazolyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isooxazolyl group, 4 -Isooxazolyl group, 5-isoxazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 4- (1,2,3-thiadiazolyl) group, 5- (1,2,3-thiadiazolyl) group, 3- (1,2,5-thiadiazolyl) group, 2- (1,3,4-thiadiazoli) Lu) group, 4- (1,2,3-oxadiazolyl) group, 5- (1,2,3-oxadiazolyl) group, 3- (1,2,4-oxadiazolyl) group, 5- (1,2, 4- (1,2,5-oxadiazolyl) group, 3- (1,2,5-oxadiazolyl) group, 2- (1,3,4-oxadiazolyl) group, 1- (1,2,3-triazolyl) group, 4- (1, 2,3-Triazolyl) group, 5- (1,2,3-triazolyl) group, 1- (1,2,4-triazolyl) group, 3- (1,2,4-triazolyl) group, 5- ( 1,2,4-triazolyl) group, 1-tetrazolyl group, 5-tetrazolyl group, 1-indrill group, 2-indrill group, 3-indrill group, 4-indrill group, 5-indrill group, 6-indrill group, 7-Indrill group, 1-isoindrill group, 2-isoindrill group, 3-isoindrill group, 4-isoindrill group, 5-isoindrill group, 6-isoindrill group, 7-isoindrill group, 1-benzoimidazolyl group, 2-benzoimidazolyl group, 4-benzoimidazolyl group, 5-benzoimidazolyl group, 6-benzoimidazolyl group, 7-benzoimidazolyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7-isobenzofunyl group, 2-benzothienyl group , 3-benzothienyl group, 4-benzothienyl group, 5-benzothienyl group, 6-benzothienyl group, 7-benzothienyl group, 2-benzoxazolyl group, 4-benzoxazolyl group, 5-benzo Oxazolyl group, 6-benzoxazolyl group, 7-benzoxazolyl group, 2-benzothiazolyl group, 4-benzothiazolyl group, 5-benzothiazolyl group, 6-benzothiazolyl group, 7-benzothiazolyl group, 1-indazolyl group , 3-Indazolyl group, 4-Indazolyl group, 5-Indazolyl group, 6-Indazolyl group, 7-Indazolyl group, 2-Molholyl group, 3-Morphoryl group, 4-Morholyl group, 1-Piperazyl group, 2-Piperazyl group , 1-piperidyl group, 2-piperidyl group, 3-piperidyl group, 4-piperidyl group, 2-tetrahydropyranyl group, 3-tetrahydropyranyl group, 4-tetrahydropyranyl group, 2-tetrahydrothiopyrani Lu group, 3-tetrahydrothiopyranyl group, 4-tetrahydrothiopyranyl group, 1-pyrrolidyl group, 2-pyrrolidyl group, 3-pyrrolidyl group, 2-tetrahydrofuranyl group, 3-tetrahydrofuranyl group, 2-tetrahydrothienyl Examples include a group, a 3-tetrahydrothienyl group and the like. Among them, the preferred heterocyclic group is a pyridyl group, a furanyl group, a thienyl group, a pyrimidyl group or a pyrazil group, and more preferably a pyridyl group.

In the present specification, the "amino group" includes not only the amino group represented by -NH ₂ but also, for example, a methylamino group, an ethylamino group, an n-propylamino group, an isopropylamino group and an n-butylamino group. , Isobutylamino group, s-butylamino group, t-butylamino group, 1-ethylpropylamino group, n-pentylamino group, neopentylamino group, n-hexylamino group, isohexylamino group, 3-methylpentyl A linear or branched monoalkylamino group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as an amino group; 1 to 6 carbon atoms such as a dimethylamino group, an ethylmethylamino group and a diethylamino group (particularly). Substituted amino groups such as dialkylamino groups having two linear or branched alkyl groups having 1 to 4 carbon atoms are also included.

Each of these alkyl group, alkylthio group, aralkyl group, aryl group, arylthio group, heterocyclic group, and amino group may have one or more substituents. The "substituted group" is not particularly limited, and is, for example, a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carboxyl group, a carboxyalkyl group, a formyl group and a nitrile group. , Nitro group, alkyl group, hydroxyalkyl group, hydroxyl group, alkoxy group, aryl group, aryloxy group, heterocyclic group, thiol group, alkylthio group, arylthio group and the like. The substituent may preferably have 1 to 5, more preferably 1 to 3.

In the present specification, examples of the "halogen atom" include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, preferably a chlorine atom, a bromine atom, and an iodine atom.

In the present specification, the "aminoalkyl group" is not particularly limited, and examples thereof include aminoalkyl groups such as aminomethyl group, 2-aminoethyl group, and 3-aminopropyl group.

In the present specification, the "alkoxycarbonyl group" is not particularly limited, and examples thereof include a methoxycarbonyl group and an ethoxycarbonyl group.

In the present specification, the "acyl group" is not particularly limited, and examples thereof include a linear or branched alkylcarbonyl group having 1 to 4 carbon atoms such as an acetyl group, a propionyl group, and a pivaloyl group.

In the present specification, the "acyloxy group" is not particularly limited, and examples thereof include an acetyloxy group, a propionyloxy group, and an n-butyryloxy group.

In the present specification, the "amide group" is not particularly limited, and for example, a carboxylic acid amide group such as an acetamido group or a benzamide group; a thioamide group such as a thioacetamide group or a thiobenzamide group; an N-methylacetamide group or N. -N-substituted amide groups such as benzylacetamide groups; and the like.

In the present specification, the "carboxyalkyl group" is not particularly limited, and is, for example, a carboxymethyl group, a carboxyethyl group, a carboxy-n-propyl group, a carboxy-n-butyl group, a carboxy-n-pentyl group, and a carboxy group. Examples thereof include a carboxy-alkyl group such as an -n-hexyl group (preferably an alkyl group having a carboxy group and having 1 to 6 carbon atoms).

In the present specification, the "hydroxyalkyl group" is not particularly limited, and is, for example, a hydroxy-alkyl group such as a hydroxymethyl group, a hydroxyethyl group, a hydroxy-n-propyl group, or a hydroxy-n-butyl group (preferably). Alkyl groups having 1 to 6 carbon atoms having a hydroxy group) can be mentioned.

In the present specification, the "alkoxy group" is not particularly limited, and examples thereof include linear, branched or cyclic alkoxy groups, and specific examples thereof include methoxy group, ethoxy group and n-propoxy. A linear group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) of a group, an isopropoxy group, an n-butoxy group, a t-butoxy group, an n-pentyloxy group, a neopentyloxy group, and an n-hexyloxy group. Or a branched alkoxy group; having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, and a cyclooctyloxy group. Cyclic alkoxy groups and the like can be mentioned.

In the present specification, the "aryloxy group" is not particularly limited, and examples thereof include a phenoxy group, a biphenyloxy group, and a naphthoxy group.

The "salt" of the tetrazine compound represented by the general formula (1) is not particularly limited and includes all kinds of salts. Examples of such salts include inorganic acid salts such as hydrochlorides, sulfates and nitrates; organic acid salts such as acetates and methanesulfonates; alkali metal salts such as sodium salts and potassium salts; magnesium salts and calcium. Alkaline earth metal salts such as salts; ammonium salts such as dimethylammonium and triethylammonium can be mentioned.

Among these tetrazine compounds (1), preferable compounds are an alkyl group in which X ¹ and X ² are the same or different and may have a substituent, an aralkyl group which may have a substituent, and a substitution. A compound which is an aryl group which may have a group or a heterocyclic group which may have a substituent.

In the more preferable tetradine compound (1), X ¹ and X ² have an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent, which may be the same or different. It is a compound which is a heterocyclic group which may be used.

A more preferable tetrazine compound (1) is a 2-pyridyl group in which X ¹ and X ² are the same or different and may have a substituent, and a 3-pyridyl group which may have a substituent. Compounds are particularly preferred.

Specifically, as the tetrazine compound (1), for example,
1,2,4,5-Tetrazine,
3,6-bis (2-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (3-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (4-pyridyl) -1,2,4,5-tetrazine,
3,6-Diphenyl-1,2,4,5-Tetrazine,
3,6-Dibenzyl-1,2,4,5-Tetrazine,
3,6-Bis (2-Franyl) -1,2,4,5-Tetrazine,
3-Methyl-6- (3-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (3,5-dimethyl-1-pyrazolyl) -1,2,4,5-tetrazine, 3,6-bis (2-thienyl) -1,2,4,5-tetrazine,
3-Methyl-6- (2-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (4-hydroxyphenyl) -1,2,4,5-tetrazine,
3,6-bis (3-hydroxyphenyl) -1,2,4,5-tetrazine,
3,6-bis (2-pyrimidinyl) -1,2,4,5-tetrazine,
Examples thereof include 3,6-bis (2-pyrazyl) -1,2,4,5-tetrazine.

Among them, the preferred tetrazine compound (1) is 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine and 3,6-bis (3-pyridyl) -1,2,4,5-. Tetrazine, 3,6-bis (2-furanyl) -1,2,4,5-tetrazine, 3-methyl-6- (3-pyridyl) -1,2,4,5-tetrazine, and 3-methyl- 6- (2-Pyridyl) -1,2,4,5-tetrazine, and a more preferable tetrazine compound (1) is 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, And 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine.

By adding the tetrazine compound (1) to the rubber component, high resilience can be imparted to the rubber composition. A golf ball produced (manufactured) from a rubber composition containing such a tetrazine compound (1) can have high hardness and high strength, and energy loss is reduced, resulting in high durability and high resilience performance. Express.

A modified polymer is produced by treating the rubber component with the tetrazine compound (1). This is because the reverse electron-required Aza-Diels-Alder reaction proceeds between the double bond of the diene-based rubber in the rubber component and the tetrazine compound (1).

Further, when a modified diene-based rubber having a substituent such as an epoxy group, an amino group, an alkoxysilyl group, or a hydroxyl group is used as the rubber component, a further modified polymer is produced by the action of the tetrazine compound (1). Can be done.

As a specific method for producing the modified polymer, the rubber component and the tetrazine compound (1) are kneaded under heating conditions.

The blending amount of the tetrazine compound (1) is not particularly limited, and is, for example, usually 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it may be appropriately adjusted and used so as to be 0.5 to 2 parts by mass.

The heating temperature is not particularly limited, and for example, the upper limit of the temperature of the rubber composition is preferably 80 to 190 ° C, more preferably 90 to 160 ° C, and 100 to 150 ° C. More preferred.

The mixing time or kneading time is not particularly limited, and is preferably, for example, 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 7 minutes.

When the rubber component is a liquid (liquid), a method of mixing the solution or emulsion (suspension) of the rubber component with the tetrazine compound (1) under heating conditions (liquid mixing method) and the like can be mentioned.

In this case, the blending amount of the tetrazine compound (1) may be the same as above, and is usually 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass with respect to 100 parts by mass of the rubber component. Yes, more preferably 0.5 to 2 parts by mass may be appropriately adjusted and used.

The heating temperature is not particularly limited, and the upper limit of the temperature of the liquid rubber composition is preferably 80 to 190 ° C, more preferably 90 to 160 ° C, and further preferably 100 to 150 ° C. preferable.

The mixing time or kneading time is not particularly limited, and is preferably, for example, 10 seconds to 60 minutes, more preferably 30 seconds to 40 minutes, and even more preferably 60 seconds to 30 minutes.

After the mixing reaction, for example, the solvent in the mixture can be blown off (removed) under reduced pressure to recover the solid rubber composition.

The obtained modified polymer can be blended with a cross-linking agent, a co-crosslinking agent and the like to obtain the rubber composition of the present invention, and an inorganic filler can be appropriately blended as needed.

Cross-linking agent The rubber composition of the present invention contains a known cross-linking agent used in a rubber composition for golf balls. Among such cross-linking agents, organic peroxides are preferably used. The organic peroxide decomposes by heat to generate radicals, and the repulsion can be improved by increasing the degree of cross-linking between the co-crosslinking agent and the rubber component.

Specific examples of organic peroxides include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, and 2,5-dimethyl-2,5-di-(. Examples thereof include t-butylperoxy) hexane, 1,3-bis (t-butylperoxy-isoropyl) benzene, and di-t-butyl peroxide. Organic peroxides can be used alone or in combination of two or more.

Co-crosslinking agent A co-crosslinking agent is blended in the rubber composition of the present invention.

The co-crosslinking agent has a function of cross-linking itself and also reacting with rubber molecules to cross-link and polymerize the whole.

As the co-crosslinking agent, as long as it is a co-crosslinking agent usually used in the rubber industry, there is no particular limitation and a known co-crosslinking agent can be widely used. Examples of such a co-crosslinking agent include monovalent or divalent metal salts of α, β-unsaturated carboxylic acid, and more specifically, acrylic acid, methacrylic acid, itaconic acid, and maleic acid. , Fumaric acid, crotonic acid, sorbic acid, tigric acid, silicic acid, aconitic acid and other metal salts. Specific examples of the metal salt include alkali metal salts such as lithium salt, sodium salt and potassium salt; alkaline earth metal salts such as magnesium salt, calcium salt and barium salt; and other metal salts such as zinc salt. Among these metal salts of α, β-unsaturated carboxylic acid, zinc acrylate and zinc methacrylate can be preferably used. In addition, these co-crosslinking agents can be used individually by 1 type or in combination of 2 or more types.

In order to include the metal salt of α, β-unsaturated carboxylic acid in the rubber composition, the metal salt of α, β-unsaturated carboxylic acid itself may be mixed with the rubber component or the like. Alternatively, α, β-unsaturated carboxylic acid in the rubber composition is obtained by further adding α, β-unsaturated carboxylic acid to the rubber composition kneaded with a metal oxide, a metal hydroxide, or the like and kneading the mixture. The acid and the metal oxide may be reacted to form a metal salt. Further, in the case of a divalent metal salt, a completely neutralized type or a partially neutralized type may be used.

Inorganic filler The inorganic filler is not particularly limited as long as it is an inorganic compound usually used in the rubber industry. Examples of the inorganic compounds that can be used include silica; alumina such as γ-alumina and α-alumina (Al ₂ O ₃ ); alumina monohydrate such as boehmite and diaspore (Al ₂ O ₃・ H ₂ O); gibsite. , Aluminum hydroxide [Al (OH) ₃ ] such as Bayarite; Aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], Magnesium hydroxide [Mg (OH) ₂ ], Magnesium oxide (MgO), Magnesium carbonate (MgCO ₃ ) ), Tarku (3MgO ・ 4SiO ₂・ H _2O ), Attapulsite (5MgO ・ 8SiO ₂・ 9H _2O ), Titanium White (TIO ₂ ), Titanium Black (TIO _2n-1 ), Calcium Oxide (CaO), Hydroxide Calcium [Ca ₍ OH) ₂ ], magnesium oxide ₍ MgO ・_Al2O3 ) _, clay _{( Al2O3.2SiO 2} ), kaolin _{( Al2O3.2SiO2.2H2O} ), pyrophyllite (Al ₂ O 3.4SiO ₂・ H ₂ O), _Bentnite (Al ₂ O _{3.4SiO 2.2H 2} O), Aluminum silicate ₍ Al ₂ SiO ₅ , Al _4.3SiO 4.5H ₂ O, etc.), Magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), Calcium silicate (Ca ₂ · SiO ₄ etc.), Aluminum oxide calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), Magnesium magnesium silicate (CaMgSiO ₄ etc.) ), Calcium carbonate (CaCO ₃ ), zinc oxide (ZnO), barium sulfate (BaSO ₄ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O], zirconium carbonate [Zr (CO) ₃ ) ₂ ], crystalline aluminosilicates containing hydrogen, alkali metal or alkaline earth metal, which correct the charge like various zeolites, and the like can be mentioned. In these inorganic fillers, the surface of the inorganic filler may be organically treated in order to improve the affinity with the rubber component.

Among these inorganic fillers, zinc oxide, barium sulfate, calcium carbonate, and silica are preferable, and zinc oxide is more preferable, from the viewpoint of imparting strength to rubber.

These inorganic fillers can be used alone or in combination of two or more.

The blending amount of the inorganic filler is usually 5 to 130 parts by mass, preferably 7.5 to 50 parts by mass, and more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the rubber component.

Other Blending Agents In addition to the tetrazine compound (1), cross-linking agents, co-cross-linking agents, and inorganic fillers, the rubber compositions of the present invention also contain blending agents commonly used in the rubber industry, such as anti-aging. Agents, lubricants such as stearic acid, sulfur, softeners, processing aids, waxes, resins, foaming agents, oils, vulcanization accelerators, vulcanization retarders, etc. are appropriately selected within a range that does not impair the object of the present invention. Can be compounded. Commercially available products can be used as these compounding agents.

Further, from the viewpoint of adjusting the hardness and the resilience, the organic sulfur compound can be blended in the rubber composition of the present invention. Examples of such an organic sulfur compound include thiophenol, thionaphthol, halogenated thiophenol or a metal salt thereof, and more specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol and para. Zinc salts such as chlorothiophenol and pentachlorothiophenol, diphenylpolysulfide having 2 to 4 sulfur numbers, dibenzylpolysulfide, dibenzoylpolysulfide, dibenzothiazoylpolysulfide, dithiobenzoylpolysulfide and the like can be mentioned. These organic sulfur compounds can be used alone or in combination of two or more.

Method for Producing Rubber Composition The method for producing the rubber composition of the present invention is not particularly limited and can be produced by a conventionally known method, for example, a rubber component, a tetradine compound (1), a cross-linking agent, and a cross-linking agent. Examples thereof include a method including a step (A) of kneading a raw material component containing a co-crosslinking agent.

Further, as another kneading method in the step (A), there is a step (A-1) of kneading the rubber component and the tetrazine compound (1), and a mixture (modified polymer) obtained in the step (A-1). Examples thereof include a two-step kneading method including a step (A-2) of kneading a cross-linking agent, a co-cross-linking agent, and, if necessary, a raw material component including an inorganic filler and other compounding components. ..

In the step (A), the double bond portion of the rubber component (diene-based rubber) reacts with the tetrazine compound (1) to form a modified polymer, and a mixture in which the co-crosslinking agent and the inorganic filler are suitably dispersed is obtained. Obtainable.

The rubber composition in the present invention is mixed or kneaded using a Banbury mixer, a roll, an intensive mixer, a kneader, a twin-screw extruder and the like.

2. 2. Golf ball core A golf ball core can be obtained by using a known method such as vulcanization molding in a mold using the rubber composition. The vulcanization conditions at this time are not particularly limited, and are usually carried out at 100 to 240 ° C. for 10 to 60 minutes, preferably 130 to 200 ° C. for 10 to 40 minutes.

The specific gravity of the golf ball core is preferably 0.9 to 1.5, more preferably 1.0 to 1.3.

The hardness of the golf ball core is preferably 35 to 60, more preferably 40 to 50, according to JIS-D hardness (JIS K6253).

The diameter of the golf ball core may be appropriately set according to the mode of the solid golf ball (two-piece golf ball, three-piece golf ball, etc.).

3. 3. Golf Ball The golf ball of the present invention is a solid golf ball produced by using a rubber composition containing a tetrazine compound (1) or a modified polymer, and can take various golf ball modes.

The use of the solid golf ball is not particularly limited, and examples thereof include a one-piece solid golf ball, a two-piece solid golf ball, and a multi-piece solid golf ball. The golf ball of the present invention can be suitably used for these applications.

The golf ball of the present invention can be produced by a known method of vulcanizing or curing the rubber composition of the present invention. For example, the rubber composition of the present invention can be made into a one-piece golf ball by a method of heat-pressing molding using a mold. The vulcanization conditions are usually 100 to 240 ° C. for 10 to 60 minutes, preferably 130 to 200 ° C. for 10 to 40 minutes.

The multi-piece golf ball of the present invention can be produced by coating the golf ball core made from the rubber composition of the present invention with a cover resin mainly made of a thermoplastic resin, an intermediate layer, or the like. The coating method for the cover resin, the intermediate layer, or the like can be performed by using a generally known method, and is not particularly limited. For example, a method of covering the core with two hemispherical shell-shaped materials obtained by molding the coating composition and heat-pressing molding, or a method of directly injecting the coating composition into the core and molding the core can be mentioned. be able to.

Dimples may be formed on the obtained golf ball, and if necessary, a paint finish or a logo or the like may be printed on the obtained golf ball.

The shape, structure, size and material of the golf ball of the present invention are not particularly limited and may be appropriately selected according to the golf regulations.

According to the present invention, since the strength and hardness of the golf ball are improved and the energy loss can be reduced, it is possible to provide a golf ball having high resilience and durability.

Hereinafter, the present invention will be specifically described with reference to production examples and examples. However, the examples are merely examples, and the present invention is not limited to the examples.

Physical properties of vulcanized product Hardness Measured at room temperature using a type D durometer according to the measuring method specified in JIS-K6253. A rubber composition (reference) was prepared by the same formulation and the same manufacturing method as in each example except that the tetrazine compound was not added, and the reciprocal of the hardness was set to 100. The hardness index was calculated based on the following formula. Further, the hardness of the vulcanized rubber composition of each reference is 100.
Formula: Hardness index = {(Hardness of rubber composition to which tetrazine compound (1) is not added) / (Hardness of rubber composition of the present invention)} × 100

Tensile strength The tensile strength at break was measured according to ASTM-D412. The larger the value, the higher the tensile strength. For comparison, rubber compositions (references) were prepared with the same formulation and the same manufacturing method as in each example except that the tetrazine compound was not added, and the reciprocal of their tensile strength was set to 100. The index of tensile strength was calculated based on the following formula. Further, the tensile strength of the vulcanized rubber composition of each reference is 100.
Formula: Tensile strength index = {(tensile strength of rubber composition to which tetrazine compound (1) is not added) / (tensile strength of rubber composition of the present invention)} × 100

Loss coefficient (tanδ index)
For the rubber compositions of Examples 1 and 2 below, tan δ was measured at a temperature of 40 ° C., a dynamic strain of 5%, and a frequency of 15 Hz using a viscoelasticity measuring device (manufactured by Metravib). For comparison, rubber compositions (references) were prepared with the same formulation and the same manufacturing method as in each example except that the tetrazine compound was not added, and the reciprocal of tan δ was set to 100. The index of the loss coefficient was calculated based on the following formula. The larger the index value of the loss coefficient, the lower the energy loss and the greater the resilience. Further, the loss coefficient of the vulcanized rubber composition of each reference is 100.
Formula: Loss coefficient index = {(tan δ of rubber composition to which tetrazine compound (1) is not added) / (tan δ of rubber composition of the present invention)} × 100

Production Example 1: Kneading of Modified Polymers Each rubber component and the tetrazine compound shown in Production Table 1 were kneaded at their ratios (parts by mass) using a Banbury mixer. From the time when the temperature of the mixture reached 130 to 150 ° C., the mixture was kneaded for about 2 minutes while adjusting to maintain the temperature, and then cooled with a roll mill to produce a modified polymer.

[Explanation of symbols in the table]
The raw materials used in the examples (in the table) are shown below.
* 1: Butadiene rubber (BR), manufactured by JSR Corporation, product name "BR01"
* 2: Zinc oxide, manufactured by Dalian Zinc Oxide Co., Ltd. * 3: Zinc acrylate, manufactured by Asahi Kasei Chemicals Co., Ltd., trade name "Zinc Acrylate"
* 4: Dicumylperoxide, manufactured by LANXESS, trade name "DCP"
* 5: Tetrazine compound (1a): 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, manufactured by Tokyo Chemical Industry Co., Ltd. * 6: Modified BR manufactured in Production Example 1.

Examples 1 and 2
After preparing the rubber composition having the composition shown in Table 2 below, vulcanization was carried out at 160 ° C. for 20 minutes.

The rubber compositions of all the examples showed high hardness, high tensile strength and high resilience with respect to the comparative rubber composition to which the tetrazine compound was not added.

By using the rubber composition of the present invention, a golf ball having high resilience can be produced.

Claims (4)

A rubber composition containing a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof, a cross-linking agent, and a co-cross-linking agent.
General formula (1):

[In the formula, X ¹ and X ² represent a heterocyclic group . Each of these groups may have one or more substituents. ] A rubber composition containing a modified polymer obtained by treating a tetrazine compound represented by the following general formula (1) or a salt thereof, a cross-linking agent, and a co-cross-linking agent in a rubber component.

[In the formula, X ¹ and X ² represent a heterocyclic group. Each of these groups may have one or more substituents. ] The rubber composition according to claim 1 or 2 , further comprising an inorganic filler. A golf ball produced by using the rubber composition according to any one of claims 1 to 3 .