WO2018117202A1 - Rubber composition and golf ball - Google Patents

Abstract

A rubber composition which contains: a rubber component; a tetrazine compound represented by general formula (1) or a salt thereof; a crosslinking agent; and a co-crosslinking agent. (In general formula (1), X¹ and X² may be the same or different and each represents 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; and each one of these groups may have one or more substituents.)

Description

Rubber composition and golf ball

The present invention relates to a rubber composition and a golf ball.

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

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

In order to improve the resilience performance of golf balls, many various rubber compositions have been proposed. Mainly, (1) a rubber composition 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 whose active terminal is modified with an alkoxysilane compound (for example, Patent Document 3 and 4) and the like. However, the resilience performance of golf balls manufactured from these rubber compositions is not satisfactory for users, and development of rubber compositions that can further improve the flight distance of golf balls is eagerly desired.

JP 2013-108078 A JP 2002-338748 A JP 2009-119256 A JP 2008-161345 A

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

Another object of the present invention is to provide a golf ball excellent in high resilience.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a high rebound can be imparted to the rubber composition by blending a specific tetrazine compound into the rubber composition. As a result of further investigation based on such knowledge, the present inventors have completed the present invention.

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

[Wherein, X ¹ and X ² are the same or different and each represents 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. 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 comprising a rubber component, a modified polymer obtained by treating a tetrazine compound represented by the general formula (1) or a salt thereof, a crosslinking agent, and a co-crosslinking agent.
Item 4.
Item 3. The rubber composition according to Item 1 or 2, comprising 0.1 to 10 parts by mass of the 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 4. The rubber according to Item 3, wherein the modified polymer is a modified polymer obtained by treating 0.1 to 10 parts by mass of the tetrazine compound represented by the general formula (1) or a salt thereof with respect to 100 parts by mass of the rubber component. Composition.
Item 6.
Item 6. The rubber composition according to any one of Items 1 to 5, comprising 0.1 to 10 parts by mass of a crosslinking 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 7. The rubber composition according to any one of Items 1 to 6, wherein the diene rubber is 50 parts by mass or more in 100 parts by mass of the rubber component.
Item 8.
Item 8. The rubber composition according to Item 7, wherein the diene rubber contains butadiene rubber.
Item 9.
Item 7. The rubber composition according to Item 1, 2, 3, or 6, wherein the crosslinking agent is an organic peroxide.
Item 10.
Item 7. The rubber composition according to Item 1, 2, 3, or 6, wherein the co-crosslinking agent is a metal salt of an α, β-unsaturated carboxylic acid.
Item 11.
Item 11. The rubber composition according to any one of Items 1 to 10, further comprising an inorganic filler.
Item 12.
Item 12. The rubber composition according to Item 11, containing 5 to 130 parts by mass of an inorganic filler with respect to 100 parts by mass of the rubber component.
Item 13.
Item 13. The rubber composition according to Item 11 or 12, wherein the inorganic filler is zinc oxide.
Item 14.
Item 14. The rubber composition according to any one of Items 1 to 13, which is used for a golf ball core.
Item 15.
A modified polymer obtained by treating 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 a rubber component.
Item 16.
15. A golf ball core produced using the rubber composition according to any one of items 1 to 14.
Item 17.
Item 17. A golf ball comprising the golf ball core according to item 16.
Item 18.
Item 15. A golf ball produced 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, thereby exhibiting high resilience.

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

Furthermore, since the rubber composition of the present invention has excellent durability in addition to high resilience, a golf ball having high resilience and excellent durability can be provided.

Details of the present invention will be described below.

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 sometimes referred to as “tetrazine compound (1)”), a crosslinking agent and a co-agent. Contains a crosslinking agent.
General formula (1):

[Wherein, X ¹ and X ² are the same or different and each represents 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. Each of these groups may have one or more substituents. ]

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

In the rubber composition of the present invention, the compounding 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 compounding amount of the crosslinking agent is usually 0.1 to 10 parts by weight, preferably 0.2 to 7.5 parts by weight, based on 100 parts by weight of the rubber component. The amount is preferably 0.5 to 5 parts by mass. By making the compounding quantity of a crosslinking agent into these ranges, the rubber composition obtained can be made into an appropriate hardness, the resilience can be improved, and the durability can be improved.

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

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

In addition, when mix | blending a crosslinking agent and a co-crosslinking agent, you may use the masterbatch previously mixed with the polymer.

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 strength of the golf ball produced from the rubber composition.

In the rubber composition of the present invention, the 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. For example, natural rubber (NR), synthetic diene rubber, a mixture of natural rubber and synthetic diene rubber, and others Non-diene rubbers.

Examples of natural rubber include natural rubber latex, technically rated rubber (TSR), smoked sheet (RSS), gutta percha, Tochu-derived natural rubber, guayule-derived natural rubber, and Russian dandelion-derived natural rubber. Modified natural rubbers such as modified epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber are 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), ethylene-propylene-diene ternary copolymer Polymer rubber (EPDM), styrene-isoprene-styrene terpolymer block copolymer (SIS), styrene-butadiene-styrene terpolymer block copolymer (SBS), ethylene-α-olefin copolymer rubber (SPO), ethylene Examples thereof include -α-olefin-diene copolymer rubbers, and modified synthetic diene rubbers thereof. The modified synthetic diene rubber includes a diene rubber by a modification technique such as main chain modification, one terminal modification, or both terminal 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 series. It may be contained in 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, there is no particular limitation on the glass transition point of the synthetic diene rubber.

Further, the ratio of cis / trans / vinyl in the double bond portion of natural rubber and synthetic diene rubber is not particularly limited, and any ratio can be preferably used. The number average molecular weight and 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 rubber, and preferably contains 50 parts by mass or more of diene 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 at a ratio 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 (blend) of two or more. Among these, a 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, and more preferably BR. Moreover, when mixing 2 or more types, there is no restriction | limiting in particular in these blend ratios.

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):

[Wherein, X ¹ and X ² are the same or different and each represents 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. Each of these groups may have one or more substituents. ]

In the present specification, the “alkyl group” is not particularly limited and includes, for example, a linear, branched or cyclic alkyl group, and specifically includes, for example, a methyl group, an ethyl group, and an n-propyl group. 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 Straight chain or branched alkyl group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms), such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, etc. And cyclic alkyl groups 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, more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or n -Pentyl group, particularly preferably a methyl group or an ethyl group.

In the present specification, the “alkylthio group” is not particularly limited and includes, for example, a linear, branched or cyclic alkylthio group, and specifically includes, for example, a methylthio group, an ethylthio group, and an n-propylthio group. 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 3-methylpentylthio group; a cyclopropylthio group, a cyclobutylthio group, a cyclopentylthio group, a cyclohexylthio group Cyclic alkylthio having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms), such as a cyclopentylthio group, cyclooctylthio group, etc. Etc. The. 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 examples thereof include benzyl group, phenethyl group, trityl group, 1-naphthylmethyl group, 2- (1-naphthyl) ethyl group, 2- (2-naphthyl group). ) And the like. A more preferred aralkyl group is a benzyl group or a phenethyl group, 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. A more preferred 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 examples thereof include 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazinyl group, 2-pyrimidyl group, 4-pyrimidyl group, 5-pyrimidyl group, 3-pyridyl group, 4-pyridazyl group, 4- (1,2,3-triazyl group), 5- (1,2,3-triazyl group), 2- (1,3,5- Triazyl) group, 3- (1,2,4-triazyl) group, 5- (1,2,4-triazyl) group, 6- (1,2,4-triazyl) group, 2-quinolyl group, 3- Quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6- Isoquinolyl group, 7-isoquinolyl group, 8-iso Noryl group, 2-quinoxalyl group, 3-quinoxalyl group, 5-quinoxalyl group, 6-quinoxalyl group, 7-quinoxalyl group, 8-quinoxalyl group, 3-cinnolyl group, 4-cinnolyl group, 5-cinnolyl group, 6- Cinnolyl group, 7-cinnolyl group, 8-cinnolyl group, 2-quinazolyl group, 4-quinazolyl group, 5-quinazolyl group, 6-quinazolyl group, 7-quinazolyl group, 8-quinazolyl group, 1-phthalazyl group, 4- Phthalazyl group, 5-phthalazyl group, 6-phthalazyl group, 7-phthalazyl group, 8-phthalazyl group, 1-tetrahydroquinolyl group, 2-tetrahydroquinolyl group, 3-tetrahydroquinolyl group, 4-tetrahydroquinolyl group 5-tetrahydroquinolyl group, 6-tetrahydroquinolyl group, 7-tetrahydroquinolyl group, 8-tetrahydride Quinolyl group, 1-pyrrolyl 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, 5-imidazolyl, 1-pyrazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4- Thiazolyl group, 5-thiazolyl group, 3-isoxazolyl group, 4-isoxazolyl 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-thiadiazolyl) group Ryl) group, 4- (1,2,3-oxadiazolyl) group, 5- (1,2,3-oxadiazolyl) group, 3- (1,2,4-oxadiazolyl) group, 5- (1,2, 4-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-indolyl group, 2-indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl group, 6-indolyl group, 7-indolyl group, 1-isoindolyl group, 2-isoin Lyl group, 3-isoindolyl group, 4-isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 1-benzoimidazolyl group, 2-benzoimidazolyl group, 4-benzoimidazolyl group, 5-benzimidazolyl group, 6- Benzoimidazolyl group, 7-benzimidazolyl 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 Furanyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7-isobenzofuranyl 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-benzoxazolyl 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-morpholyl group, 3-morpholyl group, 4-morpholyl 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-tetrahydrothiopyra group Nyl group, 3-tetrahydrothiopyranyl group, 4-tetrahydrothiopyranyl group, 1-pyrrolidyl group, 2-pyrrolidyl group, 3-pyrrolidyl group, 2-tetrahydrofuranyl group, 3-tetrahydrofuranyl group, 2-tetrahydrothienyl Group, 3-tetrahydrothienyl group and the like. Among them, a preferable heterocyclic group is a pyridyl group, a furanyl group, a thienyl group, a pyrimidyl group or a pyrazyl group, and more preferably a pyridyl group.

In the present specification, the “amino group” includes not only an amino group represented by —NH ₂ but also, for example, a methylamino group, an ethylamino group, an n-propylamino group, an isopropylamino group, 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 or a diethylamino group (particularly A substituted amino group such as a dialkylamino group having two linear or branched alkyl groups having 1 to 4 carbon atoms is also included.

Each of these alkyl groups, alkylthio groups, aralkyl groups, aryl groups, arylthio groups, heterocyclic groups, and amino groups may each have one or more substituents. The “substituent” is not particularly limited, and examples thereof include halogen atoms, amino groups, aminoalkyl groups, alkoxycarbonyl groups, acyl groups, acyloxy groups, amide groups, carboxyl groups, carboxyalkyl groups, formyl groups, and nitrile groups. 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, and a chlorine atom, a bromine atom, and an iodine atom are preferable.

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 examples thereof include carboxylic acid amide groups such as acetamido group and benzamide group; thioamide groups such as thioacetamido group and thiobenzamide group; N-methylacetamido group, N -N-substituted amide group such as benzylacetamide group; and the like.

In the present specification, the “carboxyalkyl group” is not particularly limited, and examples thereof include 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. And a carboxy-alkyl group such as an -n-hexyl group (preferably an alkyl group having 1 to 6 carbon atoms having a carboxy group).

In the present specification, the “hydroxyalkyl group” is not particularly limited, and examples thereof include hydroxy-alkyl groups such as hydroxymethyl group, hydroxyethyl group, hydroxy-n-propyl group, hydroxy-n-butyl group (preferably And an alkyl group having 1 to 6 carbon atoms having a hydroxy group).

In the present specification, the “alkoxy group” is not particularly limited and includes, for example, a linear, branched or cyclic alkoxy group, and specifically includes, for example, a methoxy group, an ethoxy group, an n-propoxy group. Straight chain of 1 to 6 carbon atoms (especially 1 to 4 carbon atoms) of the group, isopropoxy group, n-butoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group and n-hexyloxy group Or a branched alkoxy group having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, cyclooctyloxy group, etc. A cyclic alkoxy group etc. are 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 Examples include alkaline earth metal salts such as salts; ammonium salts such as dimethylammonium and triethylammonium.

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

In a more preferred tetrazine compound (1), X ¹ and X ² are the same or different and have an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. It is a compound that is an optionally substituted heterocyclic group.

In a more preferred tetrazine compound (1), X ¹ and X ² are the same or different and each may be an optionally substituted 2-pyridyl group or an optionally substituted 3-pyridyl group. 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-furanyl) -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 include 3,6-bis (2-pyrazyl) -1,2,4,5-tetrazine.

Among them, preferred tetrazine compounds (1) are 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine and 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine. 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 more 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.

High resilience can be imparted to the rubber composition by adding the tetrazine compound (1) to the rubber component. A golf ball made (manufactured) from such a rubber composition containing the tetrazine compound (1) can have high hardness and high strength, and energy loss is reduced. As a result, high durability and high resilience performance are achieved. To express.

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

When a modified diene rubber having a substituent such as an epoxy group, amino group, alkoxysilyl group, or hydroxyl group is used as the rubber component, a further modified polymer is produced by the action of the tetrazine compound (1). Can do. *

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

The compounding amount of the tetrazine compound (1) is not particularly limited, 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, More preferably, it may be appropriately adjusted 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 preferably 100 to 150 ° C. Further 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 further preferably 60 seconds to 7 minutes.

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

The compounding amount of the tetrazine compound (1) in this case may be the same as described 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, and more preferably 0.5 to 2 parts by mass.

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 further preferably 60 seconds to 30 minutes.

After the mixing reaction, for example, the solvent in the mixture can be removed (removed) under reduced pressure, and the solid rubber composition can be recovered.

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

Crosslinking agent The rubber composition of the present invention is blended with a known crosslinking agent used in rubber compositions for golf balls. Among such crosslinking agents, organic peroxides are preferably used. The organic peroxide is decomposed by heat to generate radicals, and the resilience can be improved by increasing the degree of crosslinking between the co-crosslinking agent and the rubber component.

Specific examples of the organic peroxide include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di- ( Examples thereof include t-butylperoxy) hexane, 1,3-bis (t-butylperoxy-isopropyl) benzene, and di-t-butylperoxide. An organic peroxide can be used individually by 1 type or in combination of 2 or more types.

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

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

The co-crosslinking agent is not particularly limited as long as it is a commonly used co-crosslinking agent in the rubber industry, and known ones can be widely used. Examples of such co-crosslinking agents include monovalent or divalent metal salts of α, β-unsaturated carboxylic acids, and more specifically, acrylic acid, methacrylic acid, itaconic acid, maleic acid. And metal salts such as fumaric acid, crotonic acid, sorbic acid, tiglic acid, cinnamic acid, and aconitic acid. 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 acids, 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 contain 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, an α, β-unsaturated carboxylic acid is further added to the rubber composition kneaded with a metal oxide or metal hydroxide, and kneaded, whereby the α, β-unsaturated carboxylic acid is added to the rubber composition. An acid and a metal oxide may be reacted to form a metal salt. In the case of a divalent metal salt, a completely neutralized type or a partially neutralized type may be used.

The inorganic filler is not particularly limited as long as it is an inorganic compound usually used in the rubber industry. Examples of 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); gibbsite Aluminum hydroxide [Al (OH) ₃ ], such as bayerite; aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO ₃ ), Talc (3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), hydroxylated Calcium [Ca (OH) ₂ ], aluminum magnesium oxide (MgO · Al ₂ O ₃ ), clay (Al ₂ O ₃ · 2SiO ₂ ), kaolin (Al ₂ O ₃ · 2SiO ₂ · 2H ₂ O), pyrophyllite (Al ₂ O ₃ · 4SiO ₂ · H ₂ O), bentonite (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 calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), 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 (C _{3) 2],} hydrogen to correct electric charge as various zeolites, crystalline aluminosilicates such as containing alkali metal or alkaline earth metal. In order to improve the affinity of the inorganic filler with the rubber component, the surface of the inorganic filler may be organically treated.

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

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

The compounding 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 compounding agents In addition to the tetrazine compound (1), the cross-linking agent, the co-crosslinking agent, and the inorganic filler, the rubber composition of the present invention includes compounding 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 purpose of the present invention Can be blended. As these compounding agents, commercially available products can be used.

Further, from the viewpoint of adjusting hardness and resilience, an organic sulfur compound can be blended with the rubber composition of the present invention. Examples of such organic sulfur compounds include thiophenol, thionaphthol, halogenated thiophenol, or metal salts thereof. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, para Examples thereof include zinc salts such as chlorothiophenol and pentachlorothiophenol, diphenyl polysulfide having 2 to 4 sulfur atoms, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzothiazoyl polysulfide, and dithiobenzoyl polysulfide. These organic sulfur compounds can be used singly or in combination of two or more.

Production method of rubber composition The production method of 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 tetrazine compound (1), a crosslinking agent, and Examples thereof include a method including a step (A) of kneading raw material components including a co-crosslinking agent.

Further, as another kneading method in the step (A), 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) and A two-stage kneading method including a step (A-2) of kneading a crosslinking agent, a co-crosslinking agent, and, if necessary, a raw material component containing an inorganic filler and other compounding components can be exemplified. .

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

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

2. Golf ball cores golf ball cores, using said rubber composition can be obtained by using a known method such as vulcanized in a mold. The vulcanization conditions at this time are not particularly limited, and it is 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, and more preferably 1.0 to 1.3.

Further, the hardness of the golf ball core is preferably 35 to 60, more preferably 40 to 50 in accordance with JIS-D hardness (JIS K6253).

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

3. Golf Ball The golf ball of the present invention is a solid golf ball produced 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 manufactured by a known vulcanization or curing method of 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 and pressure 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 composed of a thermoplastic resin, an intermediate layer, and the like. The covering method of the cover resin, the intermediate layer and the like can be generally performed using a known method and is not particularly limited. For example, a method in which the core is covered with two hemispherical shells obtained by molding a coating composition and then heat-press molding, or a method in which the coating composition is directly injected into the core and molded. be able to.

ゴ ル フ Dimples may be formed on the resulting golf ball, and a paint finish or logo may be printed as necessary.

The shape, structure, size and material of the golf ball of the present invention are not particularly limited and can 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 energy loss can be reduced, a golf ball having high resilience and durability can be provided.

Hereinafter, the present invention will be described in detail 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 measurement method specified in JIS-K6253. Except not adding a tetrazine compound, the rubber composition (reference) was produced by the same mixing | blending content and the same manufacturing method as each Example, respectively, and the reciprocal number of the hardness was set to 100, respectively. Based on the following formula, the hardness index was calculated. The hardness of each reference vulcanized rubber composition is 100.
Formula: Hardness index = {(Hardness of rubber composition not containing tetrazine compound (1)) / (Hardness of rubber composition of the present invention)} × 100

Tensile strength Tensile strength at break was measured according to ASTM-D412. It shows that tensile strength is so high that a numerical value is large. For comparison, a rubber composition (reference) was prepared with the same blending contents and the same manufacturing method as in each Example except that no tetrazine compound was added, and the reciprocal of the tensile strength was set to 100, respectively. Based on the following formula, an index of tensile strength was calculated. The tensile strength of each reference vulcanized rubber composition is 100.
Formula: Tensile strength index = {(Tensile strength of rubber composition not containing tetrazine compound (1)) / (Tensile strength of rubber composition of the present invention)} × 100

Loss factor (tan δ 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, a rubber composition (reference) was prepared with the same blending contents and the same manufacturing method as in each example except that no tetrazine compound was added, and the reciprocal of tan δ was set to 100, respectively. Based on the following formula, an index of loss factor was calculated. In addition, it shows that it is a low energy loss and the resilience is so large that the value of the index of a loss coefficient is large. The loss factor of each reference vulcanized rubber composition is 100.
Formula: Loss coefficient index = {(tan δ of rubber composition not containing tetrazine compound (1)) / (tan δ of rubber composition of the present invention)} × 100

Production Example 1: Kneading of Modified Polymer Each rubber component and tetrazine compound listed in Production Table 1 were kneaded at a ratio (parts by mass) using a Banbury mixer. When the temperature of the mixture reached 130 to 150 ° C., the mixture was kneaded for about 2 minutes while maintaining 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, trade name “BR01”
* 2: Zinc oxide, manufactured by Dalian Zinc Oxide Co., Ltd. * 3: Zinc acrylate, manufactured by Asahi Kasei Chemicals Corporation, trade name “Zinc acrylate”
* 4: Dicumyl peroxide, 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 produced in Production Example 1

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

The rubber compositions of any of the examples exhibited high hardness, high tensile strength, and high resilience relative to the comparative rubber composition to which no tetrazine compound was added.

If the rubber composition of the present invention is used, a golf ball having high resilience can be manufactured.

Claims (5)

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

   

   [Wherein, X ¹ and X ² are the same or different and each represents 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. Each of these groups may have one or more substituents. ]
2. The rubber composition according to claim 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).
3. A rubber composition comprising a rubber component, a modified polymer obtained by treating a tetrazine compound represented by the general formula (1) or a salt thereof, a crosslinking agent, and a co-crosslinking agent.
4. The rubber composition according to any one of claims 1 to 3, further comprising an inorganic filler.
5. A golf ball produced using the rubber composition according to any one of claims 1 to 4.