JP4440177B2 - Golf ball - Google Patents

Description

  The present invention relates to a golf ball that has high hardness and high rigidity but excellent durability, and more particularly relates to an improvement in a resin composition used for an outer layer portion of a golf ball.

  As the base resin constituting the cover layer and the intermediate layer, which are the outer layers surrounding the core of the golf ball, ionomer resins and polyurethane are used. Covering the periphery of a core made of a vulcanized rubber core.

  In the above, in order to increase the flight distance, it is preferable that the cover layer has a high hardness and high rigidity and is an outer layer portion having a high resilience, but such a high hardness and high rigidity cover layer is It has been pointed out that cracks are likely to occur due to repetition of the above, and the durability is inferior.

  In order to solve such problems, for example, it has been proposed that the cover layer contains fibrous aluminum borate whiskers or organic short fibers (Patent Document 1). However, since these fibrous substances have a small specific surface area, dispersion is easy, but large reinforcing materials are scattered in the resin, so the reinforcing effect is small when dispersed in the resin matrix, In order to satisfy the desired mechanical properties, it is necessary to add a large amount of reinforcing material. As a result, the resin content in the resin composition is reduced, and an important resilience cannot be obtained when a golf ball is obtained. Also, the expected durability cannot be obtained.

Moreover, adding nano fillers, such as a hydrotalcite and an octosilicate, as a reinforcing material different from the above has also been proposed (Patent Document 2). This type of nano-filler is nano-sized and therefore difficult to disperse in the resin. In particular, it must be dispersed at the particle level in hydrophobic resins such as ionomer resins and polyurethane used in the cover layer. As a result, the aggregate of particles is unevenly distributed in the resin matrix in the same manner as the above-mentioned large particle size reinforcing material, the expected degree of hardness cannot be obtained, and the durability is not sufficient. It became clear.
Japanese Patent Laid-Open No. 10-137365 JP-T-2004-504900

  The present invention has been made to solve the above-described problems, and aims to improve the flight distance by using a resin composition used for the outer layer portion, in particular, a high hardness / high rigidity resin composition for the cover layer. An object of the present invention is to provide a golf ball that is resistant to cracking and excellent in durability.

  The golf ball of the present invention comprises a resin composition having a shore D hardness of 56 or more and 75 or less, comprising a core and an outer layer portion surrounding the core, wherein the outer layer portion contains a layered silicate that is cation-treated in a resin matrix. Become. That is, the outer layer portion is a resin composition having a high hardness of 56 or more and 75 or less and excellent resilience, and is composed of a resin composition containing a cation-treated layered silicate, so that the layered silicate is contained in the resin matrix. Are well dispersed, and the characteristics of the layered silicate fine particles can be fully expressed.

  In the present invention, the resin composition preferably contains a cation-treated layered silicate in a resin matrix in an amount of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the resin.

  In the present invention, the cation species for the cation treatment are preferably at least one selected from alkali metals, alkaline earth metals, and quaternary ammonium salts, and particularly preferably quaternary ammonium salts. Further, in the quaternary ammonium salt, at least one substituent is preferably an aromatic hydrocarbon group or a carboxyl group.

  In the present invention, when a ball having high hardness and high rigidity is used, it is preferable to contain an ionomer resin as a resin component of the resin matrix.

  Furthermore, the effect of the present invention is remarkably exhibited by using the resin composition for the cover layer.

When applying the above SL resin composition to the cover layer of a golf ball, in order to optimize the compression direction and tensile direction of the elastic modulus, compression direction and tensile direction of the elastic modulus of the resin portion of the resin composition of the cover layer And α ₀ and β ₀ , respectively, and the elastic modulus in the tensile direction and the elastic modulus in the compression direction of the portion of the resin composition of the cover layer containing the layered silicate are α ₁ and β ₁ , respectively (α _{1 / β 1) / (α} 0 / β 0) is greater than 1.1.

  In the present invention, by using a cation-treated layered silicate, the dispersibility in the resin can be improved despite the fact that the layered silicate is nano-sized fine particles and originally hydrophilic. By improving the dispersibility, the layered silicate can be present in a single leaf state in the resin matrix, so that the effect as a reinforcing material is sufficiently exhibited. And the cover layer created using the resin composition containing the cation-treated layered silicate is compared with the cover layer made of the resin composition of the resin alone due to the structure of the layered silicate dispersed in a single leaf state. The amount of increase in elastic modulus in the tensile direction is larger than the amount of increase in elastic modulus in the compression direction. For this reason, the recovery | restoration with respect to the deformation | transformation at the time of a hit becomes quick, and a flight distance can be improved. In particular, when a cover layer made of a resin composition using an ionomer resin as a resin component is provided, a golf ball with excellent durability can be obtained while having a high hardness, high rigidity and high resilience.

  And since this invention is excellent in dispersion | distribution to resin, although layered silicate is nanosize-thickness microparticles | fine-particles, the addition amount of 1 to 30 mass parts is sufficient with respect to 100 mass parts of resin. The effect can be obtained.

  Further, as the cation species for the cation treatment, by using at least one selected from the group of alkali metals, alkaline earth metals and quaternary ammonium salts, the dispersion in the resin becomes good, and the quaternary ammonium salts By using a group in which at least one is substituted with an aromatic hydrocarbon group or a carboxyl group, the polarity of the layered silicate can be changed and the dispersion in the resin can be further improved. Untreated layered silicates have high hydrophilicity and are difficult to disperse in highly polar, hydrophobic resins. According to the present invention, such relatively high polarity resins such as ionomers are used. Since dispersion into a resin or the like is also possible, it is possible to achieve both flight distance and durability even with a cover layer having high hardness and high rigidity.

  The present invention will be specifically described below.

The layered silicate of the present invention is, for example, a silicate having a [(Si ₂ O ₅ ) ²⁻ ] _n structure, and is generally called a clay mineral, mica such as muscovite and biotite, smectite, Specific examples are kaolinite, clays such as bentonite mainly composed of montmorillonite, talc, chlorite and the like. Among the layered silicates, bentonite which tends to be in a single leaf state is preferable, most preferably purified bentonite. Montmorillonite.

  The layered silicate as described above is nano-sized fine particles having a primary particle thickness of 10 nm or less, and has a flat shape whose length and width are each 1 μm or less. For this reason, if very fine layered silicate is well dispersed in the resin, the effect as a reinforcing material can be sufficiently expressed, and there is also an advantage that a small amount of use is sufficient. Therefore, if the particulate layered silicate can be uniformly dispersed in the resin, the properties of the resin are not impaired. The size of the layered silicate is not particularly limited as long as it is 1 μm or less, but is preferably 700 nm or less, more preferably 500 nm or less, preferably 10 nm or more, and more preferably 50 nm or more. Further, the thickness of the layered silicate in a single leaf state can be sufficiently exhibited if it is 10 nm or less. However, in order to obtain a single leaf, the thickness is preferably 0.1 nm or more, more preferably 0. It is 5 nm or more and 5.0 nm or less.

  In general, the layered silicate as described above exists as a state of secondary particles in which each particle is aggregated by electrostatic force and Wandelworth force. Untreated layered silicate particles have high hydrophilicity, so they have very good dispersibility in water and swell immediately in aqueous solution, but they are mixed with resin for golf balls. However, when the resin composition for the outer layer portion is used, for example, it is necessary to blend with an ionomer resin, polyurethane, or the like, so that there is a problem that sufficient dispersion cannot be obtained.

  For this reason, in the present invention, in order to obtain a state in which the layered silicate is dispersed in a single leaf state in the resin matrix, a layered silicate that has been cation-treated is used.

  The reason why the affinity to the resin is improved by cation treatment of the layered silicate is not clear, but probably the inherently hydrophilic layered silicate is changed to lipophilicity by the surface cation. It is considered that the affinity with the resin has been improved. In particular, the cation-treated layered silicate of the present invention can disperse the layered silicate well even when used with a highly hydrophobic resin, whereby the layered silicate is uniformly dispersed in the resin matrix. A resin composition can be obtained.

  Then, for example, by forming a cover layer using the resin composition, the elastic modulus in each direction of the cover layer is improved, the balance between the elastic modulus in the compression direction and the tensile direction is changed, and anisotropic A high cover layer is obtained. That is, the elastic modulus in the compression direction in the cover layer is higher than that in the case of the resin alone, and the repulsive force can be improved. Further, the amount of increase in elastic modulus in the tensile direction is larger than that in the compression direction. For this reason, the balance of the elastic modulus in the tensile direction and the compression direction of the cover layer using the resin composition of the present invention exhibits higher anisotropy than that in the case of the resin alone. As a result, it is possible to provide a cover layer that recovers quickly against deformation at the time of hitting, and it is possible to suppress the amount of spin and increase the flight distance.

  The reason why the balance between the elastic modulus in the compression direction and the tensile direction changes is not clear, but in the present invention, the dispersed layered silicate is a single-leaf flat plate shape, and the ball circles according to the resin flow direction during molding. The elastic modulus in the compression direction is higher than that of the resin alone in the thickness direction, but the increase in the elastic modulus in the compression direction is the elasticity in the tensile direction. Compared to the increase in rate, it is kept low. This is considered to be because both the hard properties of the layered silicate in the tensile direction and the properties of the resin in the compression direction can be expressed.

  In addition, even when the layered silicate is uniformly dispersed, even in a resin composition having a hard resin such as an ionomer resin as a resin component, a high elastic modulus is obtained in the tensile direction, while in the direction of impact. It does not increase the elastic modulus so much in a certain compression direction. For this reason, it can be set as the outer-layer part which is excellent also in durability. In particular, when a highly polar ionomer resin having a high hardness and a high rigidity is used to improve the flight distance, the inherently hydrophilic layered silicate tends to be insufficiently dispersed, but the cation-treated layered layer of the present invention. Silicates are advantageous in that good dispersion is possible with such resins.

  Examples of the cation of the layered silicate of the present invention include those that impart affinity to the resin. For example, an alkali metal such as sodium ion or potassium ion, or a metal cation of alkaline earth metal such as calcium ion or barium ion can be used. In particular, a quaternary ammonium salt is preferable, and two or more of these may be used in combination. it can.

  The quaternary ammonium salt is preferably at least one substituent selected from an aromatic hydrocarbon group and a carboxyl group, more preferably a quaternary ammonium salt having both substituents. By using the quaternary ammonium salt having the above-described substituent, the layered silicate is imparted with polarity and is easily dispersed in a polar resin.

  Examples of the aromatic hydrocarbon group include benzyl and benzene derivatives, such as benzyl group, phenethyl group, tolyl group, xylyl group, diphenylmethyl group, and trityl group. Among these, benzyl group is preferable. .

  In addition, the carboxyl group may be aromatic or aliphatic. Preferred examples of the carboxyl group include carboxylic acid groups such as stearic acid group, myristic acid group, palmitic acid group, oleic acid group, and lauric acid group. Suitable carboxyl groups available on the market for convenience include, for example, beef tallow fatty acid groups as fats and oils.

  A preferable example of another substituent of the quaternary ammonium salt is a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. And alkyl groups such as butyl, isopropyl and the like. It may have a double bond like an unsaturated aliphatic hydrocarbon group. A heterocyclic structure in which two or more substituents form a ring may be used.

  The method for the cation treatment of the layered silicate is not particularly limited, but a suitable example is a method of performing cation treatment in advance before mixing with the resin. Although the cation treatment may be performed at the time of adjusting the resin composition, it is preferable to perform the cation treatment before mixing with the resin. The layered silicate that has been cation-treated in advance can be cation-treated uniformly throughout the particle, and the dispersion time can be shortened when it is put into the resin. Therefore, the cation treatment is preferably performed on the entire surface of the layered silicate, but can be appropriately changed in consideration of dispersibility in the resin used.

  Examples of the layered silicate as described above include Laviosa Chimica Mineralia S. et al. p. A. Dellite ™ 43B (purified montmorillonite, particle size 500 nm, thickness 1 nm, quaternary ammonium salt treatment: quaternary ammonium salt having benzyl group, beef tallow fatty acid group and two methyl groups), Dellite ™ 67G (Purified montmorillonite, particle diameter 500 nm, thickness 1 nm, quaternary ammonium salt treatment: quaternary ammonium salt having two tallow fatty acid groups and two methyl groups), Dellite (trademark) HPS (purified montmorillonite, particle diameter 500 nm, (Thickness 1 nm, Na cation treatment). Such a layered silicate is a secondary particle of about several microns due to aggregation before being dispersed in the resin, but due to its affinity with the resin, it can be dispersed to a primary particle in the resin matrix. Therefore, the layered silicate of the present invention is excellent in terms of handling at the time of preparing the resin composition.

  Next, a method for producing a golf ball using the resin composition of the present invention for the cover layer of the outer layer portion will be described. As will be described later, in the multi-piece golf ball, the resin composition can also be used as an intermediate layer.

  The cover layer of the golf ball of the present invention can be obtained by preparing a resin composition for a cover layer containing a resin component as a base material and a cation-treated layered silicate. The blending amount of the cation-treated layered silicate in the resin composition for the cover layer is not particularly limited, but is 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 100 parts by mass of the resin component. The amount is 3 parts by mass or more, preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less. Since the layered silicate of the present invention exists as fine particles in a single leaf state in the resin matrix after dispersion, the cover layer can be improved even with a small amount relative to the resin component as described above.

  The resin component of the cover layer resin composition is not particularly limited, and examples thereof include polyurethane, ionomer resin, polyamide, polyester, polyolefin, polystyrene elastomer, or a mixture thereof. In particular, the main component of the resin component is preferably a polyurethane or ionomer resin. The content of the polyurethane or ionomer resin in the resin component is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. Furthermore, it is also preferable that the resin component consists essentially of polyurethane or ionomer resin.

  The hardness of the resin composition of the present invention is preferably 56 or more, more preferably 59 or more, and most preferably 60 or more in Shore D hardness in order to obtain high resilience. On the other hand, if the hardness is too high, the effect of the layered silicate cannot catch up and durability due to impact is reduced, so 75 or less is preferable, 72 or less is more preferable, and 70 or less is most preferable.

  The high-hardness / high-rigidity resin composition can be prepared by appropriately changing the resin component, the amount of use thereof, and the amount of layered silicate added within the above ranges, but if an ionomer resin is used, the resin component Since it is easy to increase the rigidity of itself, it can be suitably used.

  In addition, the cover layer formed of the resin composition containing the layered silicate of the present invention has not only high hardness, but also the compression direction (ball diameter direction) and tension direction (ball circumferential direction) at the time of impact. It is preferable to give high anisotropy to the balance of elastic modulus. By increasing the anisotropy, the spin amount of the ball can be suppressed, the launch angle can be increased, and the flight distance can be increased. That is, it is difficult to obtain a cover layer composed only of a resin component having a high elastic modulus ratio between the compression direction and the tensile direction. This is the same as a resin composition to which a reinforcing material having an isotropic shape such as a sphere or a cube is added, and by adding such a reinforcing material, each elastic modulus itself can be increased, but in each direction. The contribution of the elastic modulus is almost the same. For this reason, the change in the balance between the elastic modulus in the compression direction and the tensile direction is small.

  On the other hand, since the present invention uses a lamellar silicate dispersed in a resin in a single-leaf state, in the compression direction of the ball, the elastic modulus does not increase significantly compared to the elastic modulus of the resin alone due to its particle shape. However, the amount of increase in elastic modulus is greater in the tensile direction than in the compression direction. Therefore, it can be set as the cover layer which has a balance of elastic modulus with high anisotropy. As a result, the deformation applied to the ball by hitting can be quickly recovered, the amount of spin can be reduced, and the flight distance can be further improved. On the other hand, since the amount of increase in elastic modulus is small in the compression direction, it is considered that a cover layer having high durability and excellent durability can be obtained while having high hardness and high rigidity.

In the present invention, from the above viewpoint, the balance between the elastic moduli of the cover layer is that the elastic modulus in the tensile direction and the elastic modulus in the compression direction of the resin part of the resin composition forming the cover layer are α ₀ and β ₀ , respectively. When the elastic modulus in the tensile direction and the elastic modulus in the compression direction of the part containing the layered silicate of the resin composition forming the cover layer are α ₁ and β ₁ , respectively, α ₁ / β ₁ is α ₀ / β It has also been found that by setting it to be larger than 1.1 with respect to ₀ , more preferably 1.2 or more, and most preferably 1.3 or more, the flight distance can be further increased and the durability can be improved.

  The balance between the two elastic moduli is preferable because the higher the elastic modulus in the tensile direction, the greater the tendency of anisotropy. However, in terms of both repulsion and durability, it is preferably 2.0 or less, more preferably 1 .8 or less, and most preferably 1.6 or less.

  Each elastic modulus can be appropriately changed according to the type of resin component used in the cover layer and the amount of layered silicate, but when an ionomer resin is used as the resin component, the elastic modulus in the compression direction of the resin portion is 20 MPa or more and 700 MPa or less, more preferably 30 MPa or more and 600 MPa or less, and most preferably 50 MPa or more and 500 MPa or less.

  Similarly, the elastic modulus in the tensile direction of the resin portion is preferably 100 MPa or more and 3000 MPa or less, more preferably 150 MPa or more and 2500 MPa or less, and most preferably 180 MPa or more and 2000 MPa or less.

  In addition, when it is difficult to directly measure each elastic modulus of the cover layer, it can be obtained by preparing a molded body of a resin matrix having the same composition as the resin composition used for the cover layer.

  Further, the elastic modulus of the cover layer comprising a resin composition containing the ionomer resin as a resin component and containing a cation-treated layered silicate is preferably 30 MPa or more and 800 MPa or less, preferably 40 MPa or more and 700 MPa in the compression direction. The following is more preferable, and 55 MPa or more and 600 MPa or less is most preferable. Similarly, the elastic modulus in the tensile direction is preferably 150 MPa or more and 3500 MPa or less, more preferably 200 MPa or more and 3200 MPa or less, and most preferably 250 MPa or more and 3000 MPa or less.

  As described above, in the present invention, an ionomer resin is preferably contained as a resin component of the cover layer resin composition in order to obtain a cover layer having high hardness and high rigidity. Examples of the ionomer resin include those obtained by neutralizing at least a part of carboxyl groups in a copolymer of ethylene and an α, β-unsaturated carboxylic acid with a metal ion, or ethylene and an α, β-unsaturated carboxylic acid. The thing which neutralized at least one part of the carboxyl group in the ternary copolymer of an acid and (alpha), (beta)-unsaturated carboxylic acid ester with a metal ion can be mentioned. Examples of the α, β-unsaturated carboxylic acid include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, and acrylic acid or methacrylic acid is particularly preferable. As the α, β-unsaturated carboxylic acid ester, for example, methyl, ethyl, propyl, n-butyl, isobutyl ester, etc. such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, etc. are used. Methacrylic acid esters are preferred. Copolymers of ethylene and α, β-unsaturated carboxylic acid, and carboxylic acid groups in the terpolymer of ethylene, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester. Examples of metal ions that neutralize at least a part include alkali metal ions such as sodium, potassium, and lithium; divalent metal ions such as magnesium, calcium, zinc, barium, and cadmium; trivalent metal ions such as aluminum; tin Other ions such as zirconium and the like can be mentioned, and sodium, zinc and magnesium ions are particularly preferably used from the viewpoint of resilience and durability.

  Specific examples of the ionomer resin include Himiran 1555, 1557, 1605, 1652, 1702, 1705, 1706, 1707, 1855, 1856 (Mitsui DuPont Polychemical), Surlyn 8945, Surlyn 9945, Surlyn 6320 (DuPont). ), IOTEK 7010, 8000 (manufactured by Exxon) and the like. As these ionomer resins, those exemplified above may be used alone or as a mixture of two or more.

  The polyurethane that can be used as the resin component of the resin composition for the cover layer is not particularly limited as long as it has a plurality of urethane bonds in the molecule. For example, by reacting polyisocyanate and polyol, It is a product in which a urethane bond is formed in the molecule, and is obtained by further reacting with a polyamine or the like, if necessary. Examples of the polyurethane include thermoplastic polyurethane and thermosetting (two-component curing type) polyurethane.

The polyurethane generally contains a polyisocyanate component and a polyol component, and further contains a polyamine component as necessary. The polyisocyanate component is not particularly limited as long as it has two or more isocyanate groups. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene. Mixtures of diisocyanates (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-bitrylene-4,4′-diisocyanate (TODI), xylylene diisocyanate ( Aromatic polyisocyanates such as XDI), tetramethylxylylene diisocyanate (TMXDI), paraphenylene diisocyanate (PPDI); 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI), hydrogenated xylylene diisocyanate (H ₆ XDI), hexamethylene diisocyanate (HDI), alicyclic polyisocyanate such as isophorone diisocyanate (IPDI) or aliphatic polyisocyanate, or a mixture of two or more.

Further, from the viewpoint of improving the scratch resistance, it is preferable to use an aromatic polyisocyanate as the polyisocyanate component of the polyurethane. By using the aromatic polyisocyanate, the mechanical properties of the resulting polyurethane are improved, and a cover layer having excellent scratch resistance can be obtained. From the viewpoint of improving the weather resistance, it is preferable to use a non-yellowing polyisocyanate (TMXDI, XDI, HDI, H ₆ XDI, IPDI, H ₁₂ MDI, etc.) as the polyisocyanate component of polyurethane. More preferably 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI) is used. This is because 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI) has a rigid structure, the mechanical properties of the resulting polyurethane are improved, and a cover layer having excellent abrasion resistance can be obtained.

  The polyol component constituting the polyurethane is not particularly limited as long as it has a plurality of hydroxyl groups, and examples thereof include a low molecular weight polyol and a high molecular weight polyol. Examples of the low molecular weight polyol include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol; glycerin, trimethylol Examples include triols such as propane and hexanetriol. Examples of the high molecular weight polyol include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); polyethylene adipate (PEA), polybutylene adipate (PBA), condensation-type polyester polyols such as polyhexamethylene adipate (PHMA); lactone-type polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols A mixture of at least two of the above-described polyols may be used.

  Although the average molecular weight of a high molecular weight polyol is not specifically limited, For example, it is preferable that it is 400 or more, More preferably, it is 1000 or more. This is because if the average molecular weight of the high molecular weight polyol becomes too small, the resulting polyurethane becomes hard and the feel at impact of the golf ball decreases. The upper limit of the average molecular weight of the high molecular weight polyol is not particularly limited, but is 10,000 or less, more preferably 8000 or less.

  Moreover, the polyamine which comprises the said polyurethane as needed is not specifically limited if it has at least 2 or more amino groups. Examples of the polyamine include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine, alicyclic polyamines such as isophoronediamine and piperazine, and aromatic polyamines.

  The aromatic polyamine is not particularly limited as long as at least two amino groups are directly or indirectly bonded to the aromatic ring. Here, being indirectly bonded means that the amino group is bonded to the aromatic ring via, for example, a lower alkylene group. The aromatic polyamine may be, for example, a monocyclic aromatic polyamine in which two or more amino groups are bonded to one aromatic ring, or an amino in which at least one amino group is bonded to one aromatic ring. It may be a polycyclic aromatic polyamine containing two or more phenyl groups.

  Examples of the monocyclic aromatic polyamine include a type in which an amino group such as phenylenediamine, toluenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine is directly bonded to an aromatic ring; and an amino group such as xylylenediamine. Examples include a type bonded to an aromatic ring via a lower alkylene group. The polycyclic aromatic polyamine may be poly (aminobenzene) in which at least two aminophenyl groups are directly bonded, or at least two aminophenyl groups intervene with a lower alkylene group or an alkylene oxide group. May be combined. Of these, diaminodiphenylalkanes in which two aminophenyl groups are bonded via a lower alkylene group are preferred, and 4,4′-diaminodiphenylmethane and its derivatives are particularly preferred.

  The thermoplastic polyurethane that can be used as the resin component of the cover layer resin composition and the thermosetting polyurethane (two-component curable polyurethane) can be prepared by appropriately combining the polyisocyanate, polyol, and polyamine. Examples of the polyurethane synthesis method include a one-shot method and a prepolymer method. The one-shot method is a method in which polyisocyanate and polyol are reacted together, and the prepolymer method is a method in which polyisocyanate and polyol are reacted in multiple stages. For example, once a low molecular weight urethane prepolymer is reacted. This is a method of further increasing the molecular weight after synthesizing the polymer.

  Thermoplastic polyurethane is generally made to have a high molecular weight to some extent by the synthesis method as described above. However, a low molecular weight urethane prepolymer is temporarily retained, and a chain length extender (or curing agent) is used when forming a cover layer. If blended to increase the molecular weight, a thermosetting polyurethane (two-component curable polyurethane) can be obtained. A known catalyst can be used for the synthesis of polyurethane. Examples of the catalyst include monoamines such as triethylamine and N, N-dimethylcyclohexylamine; N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ — Polyamines such as pentamethyldiethylenetriamine; 1,8-diazabicyclo [5,4,0] -7-undecene (DBU), cyclic diamines such as triethylenediamine; tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate Is mentioned.

  In this invention, it is also preferable to use a thermoplastic polyurethane as a resin component of the resin composition for cover layers, and also a thermoplastic polyurethane elastomer is more preferable. The thermoplastic polyurethane elastomer is a polyurethane exhibiting so-called rubber elasticity, and a cover layer having high resilience can be obtained by employing the thermoplastic polyurethane elastomer. The thermoplastic polyurethane elastomer is not particularly limited as long as it can form a cover layer by, for example, injection molding or compression molding. “Elastolan XNY90A”, “D” commercially available from BASF Polyurethane Elastomers Co., Ltd. "Lastlan XNY97A", "Elastollan XNY585", etc. can be used.

  The thermoplastic polyurethane and the thermoplastic polyurethane elastomer are not particularly limited, but include, for example, a polyisocyanate component and a high molecular weight polyol component as constituent components; a polyisocyanate component, a high molecular weight polyol component, and a low molecular weight polyol. Containing components as components; Polyisocyanate components, high molecular weight polyol components, low molecular weight polyol components and polyamine components as components; Polyisocyanate components, high molecular weight polyol components and polyamine components as components Can be mentioned.

  Moreover, in this invention, it is also preferable to use a thermosetting polyurethane as a resin component of the resin composition for cover layers. Since thermosetting polyurethane can generate many three-dimensional crosslinking points, a cover layer having excellent durability can be obtained. Examples of the thermosetting polyurethane include a type in which an isocyanate group-terminated urethane prepolymer is cured with a curing agent such as polyamine or polyol. Moreover, the type which hardens a hydroxyl group or an amino-group terminal urethane prepolymer with hardening | curing agents, such as polyisocyanate, can be mentioned. The polyamine, polyol, and polyisocyanate used as the curing agent can be appropriately selected from those described above.

Among these, as the thermosetting polyurethane, those obtained by curing an isocyanate group-terminated urethane prepolymer with a polyamine are preferable. In this case, the molar ratio (NH ₂ / NCO) of the curing agent amino group to the isocyanate group of the urethane prepolymer is 0.70 or more, more preferably 0.80 or more, and further preferably 0.85 or more. It is desirable that it is 20 or less, more preferably 1.05 or less, and still more preferably 1.00 or less. If it is less than 0.70, the amount of the isocyanate group-terminated urethane prepolymer with respect to the polyamine becomes excessive, and the formation reaction of allophanate crosslinking and burette crosslinking is likely to occur, and the flexibility of the finally obtained polyurethane becomes insufficient. On the other hand, if it exceeds 1.20, the isocyanate group is insufficient, so that allophanate and burette cross-linking reactions are difficult to occur. As a result, the number of three-dimensional cross-linking points becomes too small, and the thermosetting polyurethane finally obtained has a high strength. There is a tendency to decrease.

  As the resin component of the resin composition for a cover layer in the present invention, it is also preferable to use a thermoplastic elastomer, a diene block copolymer or the like in addition to the base resin such as the thermoplastic polyurethane or the ionomer resin. Specific examples of the thermoplastic elastomer are thermoplastic polyamide elastomers commercially available from Toray Industries, Inc. under the trade name “Pebacs” (for example, “Pebax 2533”), and trade names “Hytrel” from Toray DuPont. (E.g. "Hytrel 3548", "Hytrel 4047") thermoplastic polyester elastomer, commercially available under the trade name "Elastollan" from BASF Polyurethane Elastomers (e.g. "Elastollan ET880") Examples thereof include a thermoplastic polyurethane elastomer and a thermoplastic styrene elastomer commercially available from Mitsubishi Chemical Corporation under the trade name “Lavalon” (for example, “Lavalon SR04” and “Lavalon T3339C”).

  The diene block copolymer has a double bond derived from a conjugated diene compound of a block copolymer or a partially hydrogenated block copolymer. The block copolymer as the substrate is a block copolymer comprising a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one conjugated diene compound. It is. The partially hydrogenated block copolymer is obtained by hydrogenating the block copolymer. Examples of the vinyl aromatic compound constituting the block copolymer include one or more of styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, 1,1-diphenylstyrene, and the like. Styrene is preferred. Moreover, as a conjugated diene compound, 1 type (s) or 2 or more types can be selected from butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and the like. Isoprene and combinations thereof are preferred. Examples of a preferred diene block copolymer include a block copolymer having an SBS (styrene-butadiene-styrene) structure having a polybutadiene block containing an epoxy group, or a SIS (styrene-isoprene-styrene) having an epoxy group. Examples thereof include a block copolymer having a structure.

  Specific examples of the diene block copolymer include “Epofriend A1010” manufactured by Daicel Chemical Industries, Ltd. and “Septon HG-252” manufactured by Kuraray Co., Ltd. The amount of the thermoplastic elastomer or diene block copolymer is preferably 1 to 60 parts by mass, more preferably 1 to 35 parts by mass with respect to 100 parts by mass of the base resin.

  The resin composition for a cover layer of the present invention includes the above-described resin component and layered silicate, pigment components such as zinc oxide, titanium oxide and blue pigment, specific gravity adjusting agents such as calcium carbonate and barium sulfate, dispersants, and aging. An inhibitor, an ultraviolet absorber, a light stabilizer, a fluorescent material, a fluorescent whitening agent, or the like may be contained as long as the performance of the cover layer is not impaired.

  The structure of the golf ball of the present invention is not particularly limited as long as it has a core and an outer layer surrounding the core. A two-piece golf ball having a (single layer) core and a cover layer covering the core, Core), a multi-piece golf ball having at least one intermediate layer covering the center and a cover layer covering the intermediate layer, or a thread wound golf ball having a thread core and a cover layer covering the thread core Can be mentioned. Among these, a two-piece golf ball and a multi-piece golf ball are preferable.

  Hereinafter, although the method of manufacturing the golf ball having the cover layer will be described based on the two-piece golf ball, the present invention is not limited to such a manufacturing method. As a core of a two-piece golf ball, a conventionally known core can be used. For example, a rubber composition for a core containing a base rubber, a co-crosslinking agent, an organic peroxide, and a filler is heated and pressed. It is preferable that

  As the base rubber, natural rubber and / or synthetic rubber can be used. For example, polybutadiene rubber, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, ethylene-propylene-diene rubber (EPDM) and the like can be used. Among these, it is particularly preferable to use a high-cis polybutadiene having a cis bond advantageous for repulsion of 40% or more, preferably 70% or more, more preferably 90% or more.

  As the co-crosslinking agent, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof can be used, and examples thereof include acrylic acid, methacrylic acid, and metal salts thereof. be able to. Examples of the metal constituting the metal salt include zinc, magnesium, calcium, aluminum, and sodium, and zinc is preferably used because resilience increases. The amount of the co-crosslinking agent used is 10 parts by mass or more, more preferably 20 parts by mass or more, and 50 parts by mass or less, more preferably 40 parts by mass or less with respect to 100 parts by mass of the base rubber. desirable. When the amount of the co-crosslinking agent used is less than 10 parts by mass, the amount of the organic peroxide must be increased in order to obtain an appropriate hardness, and the resilience tends to decrease. On the other hand, when the usage-amount of a co-crosslinking agent exceeds 50 mass parts, a core may become hard too much and there exists a possibility that a shot feeling may fall.

  Examples of the organic peroxide contained in the core rubber composition include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,5-trimethylcyclohexane, and 2,5-dimethyl-2. , 5-di (t-butylperoxy) hexane, di-t-butyl peroxide and the like, and dicumyl peroxide is preferably used. 0.2-3 mass parts is preferable with respect to 100 mass parts of base rubbers, and, as for the compounding quantity of an organic peroxide, More preferably, it is 0.3-2 mass parts. If it is less than 0.2 parts by mass, the core tends to be too soft and the resilience tends to decrease. If it exceeds 3 parts by mass, it is necessary to increase the amount of co-crosslinking agent used in order to obtain an appropriate hardness. There is a lack of resilience.

  Examples of the filler contained in the core rubber composition include inorganic fillers such as zinc oxide, barium sulfate, calcium carbonate, magnesium oxide, tungsten powder, and molybdenum powder. The blending amount of the filler is 2 parts by mass or more, more preferably 3 parts by mass or more, and 50 parts by mass or less, more preferably 35 parts by mass or less with respect to 100 parts by mass of the base rubber. desirable. If the blending amount of the filler is less than 2 parts by mass, it is difficult to adjust the weight, and if it exceeds 50 parts by mass, the weight fraction of the rubber component tends to decrease and the resilience tends to decrease.

  In addition to the base rubber, co-crosslinking agent, organic peroxide, and filler, the core rubber composition further contains an organic sulfur compound, an antioxidant, a peptizer, or the like as appropriate. be able to. The blending amount of the anti-aging agent is preferably 0.1 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the base rubber. Moreover, it is preferable that a peptizer is 0.1 to 5 mass parts with respect to 100 mass parts of base rubber.

  The hot-press molding conditions for the core rubber composition may be appropriately set according to the rubber composition, but are usually heated at 130 to 200 ° C. for 10 to 60 minutes, or at 130 to 150 ° C. for 20 to 40 minutes. After heating, it is preferable to perform two-step heating at 160 to 180 ° C. for 5 to 15 minutes.

  In the present invention, the core formed as described above is covered with the cover layer described above to produce a golf ball body. When using an ionomer resin as the resin component of the cover layer resin composition, for example, with the obtained core held in a hemispherical mold, the cover layer resin composition is placed in the mold. The cover layer may be formed by injecting, then inverting the mold, and performing a curing reaction with another hemispherical mold into which the resin composition for the cover layer has been injected. The curing reaction of the resin composition for a cover layer containing the ionomer resin is desirably performed at 30 ° C. to 120 ° C., preferably 50 ° C. to 80 ° C., for 2 to 60 minutes, preferably 5 to 30 minutes.

  When a thermoplastic polyurethane, ionomer resin, thermoplastic elastomer or the like is used as the resin component of the cover layer resin composition, for example, the cover layer resin composition is previously formed into a hemispherical half shell. A method of wrapping the core using two of these and pressure molding at 110 to 170 ° C. for 1 to 10 minutes; a method of injection molding the cover layer resin composition so as to cover the core, and the like are applied. Layered silicate is contained in the resin matrix of the cover layer formed by the above method.

  The thickness of the cover layer of the golf ball of the present invention is not particularly limited, but is preferably 0.3 to 2.5 mm, more preferably 0.3 to 2.0 mm, and still more preferably 0.5 to 0.00. 9 mm. Further, when a golf ball body is manufactured by covering a cover layer, a depression called dimple is usually formed on the surface. Further, the surface of the golf ball body may be subjected to a polishing process such as a sand blast process. The golf ball of the present invention is also preferably subjected to normal paint finish, marking stamp, etc. in order to enhance aesthetics and commercial value.

  In the above-described manufacturing method, the description has been made based on the mode of the two-piece golf ball. For example, in the case of a thread-wound golf ball, a thread-wound core may be used. At least one or more intermediate layers can be provided between the two.

  The thread winding core includes a center and a thread rubber layer formed by winding a thread rubber around the center in a stretched state, and a conventionally known one can be used. As the center, either a liquid system (liquid center) or a rubber system (solid center) may be used. The thread rubber wound around the center can be the same as that conventionally used for the thread wound layer of a thread wound golf ball, for example, natural rubber or natural rubber and synthetic polyisoprene with sulfur, You may use what was obtained by vulcanizing | curing the rubber composition which mix | blended the vulcanization | cure adjuvant, the vulcanization accelerator, anti-aging agent, etc. The thread rubber is stretched about 10 times on the center and wound to form a thread wound core.

  Further, as the intermediate layer constituting the outer layer portion of the multi-piece golf ball of three or more pieces, the same resin component as the resin component contained in the cover layer can be used, for example, thermoplastic polyurethane, ionomer resin, heat Thermoplastic elastomers such as plastic polyamide elastomers, thermoplastic polyester elastomers, thermoplastic polyurethane elastomers, diene block copolymers, and the like can be used. For the intermediate layer, it is further preferable to use a resin composition containing the layered silicate of the present invention.

  The method for forming the intermediate layer is not particularly limited. For example, the intermediate layer forming material is previously formed into a hemispherical half-shell, and the two are used to wrap the solid center and press-mold, Alternatively, a method of wrapping the solid center by injection molding the intermediate layer material directly on the solid center can be adopted.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments without departing from the gist of the present invention are not limited thereto. Included in range. In addition, the usage-amount of each composition in an Example means a mass part.

[hardness]
A 2 mm thick hot press-molded sheet made from each resin composition is stored at 23 ° C. for 2 weeks, and a spring type hardness tester Shore D type is used, and an automatic rubber manufactured by Kobunshi Keiki Co., Ltd. according to ASTM-D2240. Three or more sheets were measured with a hardness meter LA1 type.

[Elastic modulus]
As a measuring device, a dynamic viscoelastic spectrometer Rheogel-E4000 manufactured by UBM was used. A sample piece having a width of 4 mm, a length of 30 mm, and a thickness of 0.5 mm prepared from each resin composition was used. The measurement is performed with a deformation site length of 20 mm, an initial load of 50 g, an amplitude of 0.025%, a frequency of 10 Hz, and a temperature distribution measurement from −100 to 100 ° C. (temperature increase rate of 2 ° C./min). The storage elastic modulus (E ′) at ° C. was read and used as the elastic modulus in the tensile direction.

Separately from the above, a sample piece having a width of 4 mm, a length of 4 mm , and a thickness of 0.5 mm was prepared using the measurement apparatus, and an initial load in the thickness direction was 600 g, an amplitude of 0.5%, and a frequency of 10 Hz. The temperature distribution was measured up to 0 ° C. (temperature increase rate 2 ° C./min), the storage elastic modulus (E ′) at −50 ° C. was read, and the elastic modulus in the compression direction was taken.

The ratio [(α ₁ / β ₁ ) / (α ₀ / β ₀ )] of the elastic modulus in the compression direction and the elastic modulus in the tensile direction depending on the presence or absence of the reinforcing material is the same as that of the resin composition consisting of the same resin composition. It was calculated | required by contrast.

[Flight performance]
(1) Launch angle A W # 1 driver made of metal head was attached to a swing robot made by True Temper, and the head was shot at a head speed of 45 m / sec, and the launch angle immediately after launch was measured. The measurement was performed 5 times and the average was obtained.

(2) Spin amount A W # 1 driver made of metal head was attached to a swing robot made by True Temper, and the head was hit at a head speed of 45 m / sec, and the back spin amount immediately after launch was measured. The measurement was performed 5 times and the average was obtained.

(3) Flying distance A W # 1 driver made of metal head was attached to a swing robot made by True Temper, and the head was hit at a head speed of 45 m / sec, and the flying distance (m) was measured. The measurement was performed 5 times and the average was obtained.

[durability]
A commercially available metal head # 1 driver was attached to the swing robot machine, each head was hit at a head speed of 45 m / second, and the number of hits until the golf ball was broken was measured. The index was evaluated based on h. A higher index indicates that the ball is less likely to break.

[Production of golf balls]
(1) Preparation of core The rubber composition for cores shown in Table 1 was kneaded and heated and pressed at 170 ° C. for 15 minutes in an upper and lower mold having hemispherical cavities to obtain spherical cores.

Polybutadiene rubber: BR18 manufactured by JSR (cis content 96% or more)
Zinc acrylate: ZNDA-90S manufactured by Nippon Distillation Co., Ltd.
Zinc Oxide: Toho Zinc Gin R
Diphenyl disulfide: Sumitomo Seika dicumyl peroxide: Nippon Oil & Fats Park Mill D

(2) Production of resin composition for outer layer part (production of half shell)
Each material shown in Table 2 and Table 3 was kneaded using a twin-screw kneading type extruder to produce pellets. The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D = 35, and the blend was heated at 230 ° C. at the die position of the extruder. Using the obtained pellets, a half shell having a thickness of 0.9 mm made of the resin composition for the cover layer was produced.

(3) Production of outer layer part Two half shells made of each resin composition obtained were bonded together, and heat-press molding was performed at 120 to 130 ° C. on the core obtained as described above. After the formation of the cover layer, paint was applied to produce a two-piece golf ball having a cover layer with a thickness of 0.8 mm.

High Milan 1605: Ionomer made by Mitsui-DuPont Polychemical High Miran 1706: Ionomer Lavalon T3339C made by Mitsui-Dupont Polychemical Co., Ltd .: Thermoplastic styrene elastomer elastollan XKP016 made by Mitsubishi Chemical Co., Ltd. BSAF Japan Thermoplastic Polyurethane Elastomer Elastollan XHM76D: BSAF Japan Thermoplastic Polyurethane Elastomer Delite 67G: Labiosa Bentonite Clay Dellite 43B: Labiosa Bentonite Clay Dellite HPS: Labiosa Bentonite Clay Aluminum Borate Whisker: Shikoku Chemical Industries Alborex YS3A (Co., Ltd.) Minoshiran surface processing type of fibrous reinforcing material, fiber length: 20 [mu] m, fiber diameter: 1.0 .mu.m)
M1030D: Nanocomposite manufactured by Unitika (layered silicate without cation treatment)

  As is clear from Tables 2 and 3 above, the resin composition No. As for 1-9, all are high hardness and the elasticity modulus is also higher than that in the case of the composition of resin alone. In addition, when the balance between the elastic modulus in the compression direction and the tensile direction is compared, the increase in the tensile direction is larger than that of the resin alone, the ratio of the balance exceeds 1.1, and a highly anisotropic cover layer is obtained. You can see that In particular, it can be seen that in a resin composition using a layered silicate that has been cation-treated with a quaternary ammonium salt, the ratio exceeds 1.2 and a highly anisotropic cover layer is obtained.

  On the other hand, resin composition No. 1 containing aluminum borate whisker, which is a conventional reinforcing material. 12 and 13 have higher elastic modulus in both the compression direction and the tensile direction, but the balance of elastic modulus in the compression direction and the tensile direction is not much different from that of the resin alone, and the elastic modulus is isotropic. It can be seen that it only increases. No. Since 15 and 19 are resin compositions using polyurethane as a resin component and not containing a reinforcing material, the hardness is insufficient.

  Next, Table 4 and Table 5 show the evaluation of the two-piece golf ball produced using the above resin composition.

  As shown in Tables 4 and 5, the golf ball No. a to g are examples using a resin composition containing a layered silicate in which a cover layer of a golf ball is cation-treated, and these golf balls are compared with golf balls having a cover layer using only the same resin. It can be seen that the launch angle can be increased, the spin rate is reduced, and the flight distance is increased. In addition, it can be seen that the durability is improved as compared with the case of the resin alone, although the cover layer has high hardness and high rigidity. Therefore, it can be seen that the present invention can provide a ball that can satisfy both the flight distance and the durability at the same time.

Claims (5)

A golf ball having a core and an outer layer portion surrounding the core, wherein the outer layer portion includes a layered silicate that is cation-treated in a resin matrix and has a Shore D hardness of 56 or more and 75 or less. Do Ri, the outer layer is a cover layer, the tensile directions and elasticity modulus of the compression direction of the alpha ₀ and beta ₀ resin portion of the resin composition of the cover _layer, the resin composition of the cover layer (Α ₁ / β ₁ ) / (α ₀ / β ₀ ) is 1.1, where α ₁ and β ₁ are the elastic modulus in the tensile direction and the elastic modulus in the compression direction of the portion containing the lamellar silicate, respectively. A larger golf ball.   The said resin composition contains the said cation-treated layered silicate in the said resin matrix in 1 mass part or more and 30 mass parts or less with respect to 100 mass parts of resin. Golf ball.   3. The golf ball according to claim 1, wherein the cationic species for the cation treatment is at least one selected from the group consisting of alkali metals, alkaline earth metals, and quaternary ammonium salts.   4. The golf ball according to claim 3, wherein at least one substituent of the quaternary ammonium salt is an aromatic hydrocarbon group or a carboxyl group. The golf ball according to claim 1, comprising an ionomer resin as a resin component of the resin matrix.