JP6962174B2 - Golf ball and its manufacturing method - Google Patents

Description

The present invention relates to a golf ball whose core is covered with a cover and a method for manufacturing the same. More specifically, the present invention is a golf ball having excellent adhesion between the outermost layer of the cover and the inner layer adjacent to the outermost layer and the method for manufacturing the golf ball. Regarding.

As a cover material for golf balls, polyurethane materials such as thermoplastic polyurethane elastomers have come to be widely used. Further, various golf balls have been proposed in which an isocyanate compound is further crosslinked with a thermoplastic polyurethane elastomer to have excellent scratch resistance and flight distance when hit by an iron. As an example thereof, JP-A-11-178949 can be used. Examples include the described golf balls.

In the molding of the cover of JP-A-11-178949, it was difficult to handle the isocyanate compound due to inactivation due to moisture, and it was difficult to obtain a stable reaction product. Further, the blocked isocyanate, which is resistant to moisture absorption, has a strong odor of the blocking agent when dissociated by heat, and is not suitable for molding a cover. Further, when the isocyanate compound is in the form of powder or solution, it is difficult to control the amount added to the thermoplastic polyurethane material, and it is difficult to control the physical characteristics of the cover. Moreover, due to the difference in melting point and the difference in melt viscosity between the thermoplastic polyurethane material and the isocyanate compound, a slip phenomenon occurs in the molding machine, and sufficient kneading may not be possible. In the technique described in the above publication, due to the above, the influence of moisture on the cover material and the control of the amount of the additive added become insufficient, and as a result, the golf ball cover is sufficiently satisfactory in terms of the effect of improving the scratch resistance. Could not get.

Further, the golf ball proposed above is a cover made of polyurethane and is particularly related to modification of the outermost layer. In recent years, the structure of a golf ball is not limited to a two-piece solid golf ball, but has a plurality of layers in the core. Many golf balls with multi-layer covers, such as covered three-piece solid golf balls and four-piece solid golf balls, are now on the market. Therefore, the spin performance and repulsion of the ball depend on the adhesion between the layers of each cover layer of the multi-layer cover. Properties and durability will have an effect, and the adhesion between layers of each cover layer is becoming an important theme in the golf ball field.

Japanese Unexamined Patent Publication No. 11-178949

The present invention has been made in view of the above circumstances, and in a golf ball having a core and a cover covering the core, the outermost layer has excellent scratch resistance, and the outermost layer and the inner layer adjacent to the outermost layer are used. It is an object of the present invention to provide a golf ball having a high degree of adhesion and a method for producing the same.

As a result of diligent studies to achieve the above object, the present inventors have made a golf ball whose core is coated with a cover, and the outermost layer of the cover is made of a resin composition containing polyurethane or polyurea as a main component. For a golf ball formed of a resin composition in which an inner layer adjacent to the outermost layer is formed of a resin composition containing a compound having a functional group that reacts with isocyanate, the surface of the inner layer is (i) blocked isocyanate and (ii). ) By treating with a treatment solution containing water or an organic solvent, the isocyanate derived from this blocked isocyanate is chemically bonded to the polyurethane or polyurea in the outermost layer and chemically to the functional group that reacts with the isocyanate in the inner layer. By doing so, it has been found that the adhesion between the outermost layer and the inner layer adjacent to the outermost layer can be improved, and the outermost layer of polyurethane or polyurea is excellent in scratch resistance, leading to the present invention. It is.

Therefore, the present invention provides the following golf balls and methods for producing the same.
1. 1. In a golf ball having a core and a cover covering the core, the outermost layer of the cover is formed of a resin composition containing polyurethane or polyurea as a main component, and the inner layer adjacent to the outermost layer reacts with isocyanate. A golf ball formed of a composition containing a compound having a functional group, and having an isocyanate derived from blocked isocyanate present at the interface between the outermost layer and the inner layer.
2. The golf ball according to 1, wherein the functional group that reacts with the above-mentioned isocyanate is one or a combination of two or more selected from a hydroxyl group, an amino group and a carboxyl group.
3. 3. The golf ball according to 1 or 2, wherein the isocyanate derived from the blocked isocyanate is an aromatic polyisocyanate.
4. 3. The golf ball according to 3, wherein the isocyanate derived from the blocked isocyanate is a polypeptide MDI.
5. The blocking isocyanate blocking agent is an oxime-based blocking agent, a phenol-based blocking agent, a lactam-based blocking agent, an alcohol-based blocking agent, an active methylene-based blocking agent, an amine-based blocking agent, a pyrazole-based blocking agent, and a heavy sulfite-based blocking agent. , A golf ball according to any one of 1 to 4 selected from the group of imidazole-based blocking agents, carbonic acid and ammonia blocking agents.
6. In the method of manufacturing a golf ball whose core is covered with a cover,
The step (1) of molding the inner layer adjacent to the outermost layer of the cover with a composition containing a compound having a functional group that reacts with isocyanate.
The step (2) of treating the surface of the inner layer with a treatment solution containing the following (i) and (ii) components (i) blocked isocyanate (ii) water or an organic solvent.
A step (3) of forming the outermost layer on the surface of the inner layer treated by the above step (2) by molding the outermost layer with a resin composition containing polyurethane or polyurea as a main component.
A method for manufacturing a golf ball, which comprises.
7. 6. The method for producing a golf ball according to 6, wherein the functional group that reacts with the isocyanate is one or a combination of two or more selected from a hydroxyl group, an amino group and a carboxyl group.
8. 6. The method for producing a golf ball according to 6 or 7, wherein the isocyanate derived from the blocked isocyanate is an aromatic polyisocyanate.
9. 8. The method for producing a golf ball according to 8, wherein the isocyanate derived from the blocked isocyanate is a polypeptide MDI.
10. The blocking isocyanate blocking agent is an oxime-based blocking agent, a phenol-based blocking agent, a lactam-based blocking agent, an alcohol-based blocking agent, an active methylene-based blocking agent, an amine-based blocking agent, a pyrazole-based blocking agent, and a heavy sulfite-based blocking agent. , The method for producing a golf ball according to any one of 6 to 9, which is selected from the group of imidazole-based blocking agents, carbonic acid and ammonia blocking agents.
11. The method for producing a golf ball according to any one of 6 to 10, further comprising a step (4) for heating the golf ball including the outermost layer after molding the outermost layer.
12. 11. The method for producing a golf ball according to 11, wherein the heating temperature in the step (4) is 40 to 120 ° C.
13. 11. The method for producing a golf ball according to 11 or 12, wherein the heating time in the step (4) is 5 to 120 minutes.

According to the golf ball of the present invention and the method for producing the golf ball, the adhesion between the outermost layer and the inner layer adjacent to the outermost layer is improved by the isocyanate derived from the blocked isocyanate, and the outermost layer made of polyurethane or polyurea has scratch resistance. It is excellent.

It is the schematic of the guillotine test apparatus used for evaluating the damage property of the outermost layer. It is explanatory drawing of the test piece for measurement used when measuring the adhesive strength between the outermost layer and the intermediate layer of a cover.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention has a core and a cover. The core is not particularly limited, and various cores such as a solid core for a two-piece ball, a solid core having a plurality of vulcanized rubber layers, a solid core having a plurality of resin layers, and a pincushion core having a rubber thread layer can be used. be. There are no restrictions on the outer diameter, mass, hardness, material, etc. of the core.

The cover of the present invention covers the core and is composed of one layer or a plurality of layers, and the outermost layer of each layer of the cover is molded by a resin composition containing polyurethane or polyurea as a main component. In this case, the proportion of polyurethane or polyurea in the entire resin composition is not particularly limited, but can be 50% by mass or more, preferably 80% by mass or more. The above polyurethane or polyurea will be described below.

Polyurethane The structure of polyurethane consists of a soft segment made of a high molecular weight polyol (polymeric glycol) which is a long-chain polyol, and a chain extender and a polyisocyanate constituting the hard segment. Here, as the polymer polyol used as a raw material, any of those conventionally used in the technology related to polyurethane materials can be used and is not particularly limited. For example, polyester-based polyols, polyether-based polyols, polycarbonate polyols, polyester polycarbonate polyols, polyolefin-based polyols, conjugated diene polymerization-based polyols, castor oil-based polyols, silicone-based polyols, vinyl polymerization-based polyols, and the like can be mentioned. As the polyester-based polyol, specifically, adipate-based polyols such as polyethylene adipate glycol, polypropylene adipate glycol, polybutadiene adipate glycol, and polyhexamethylene adipate glycol, and lactone-based polyols such as polycaprolactone polyol can be adopted. Examples of the polyether polyol include poly (ethylene glycol), poly (propylene glycol), poly (tetramethylene glycol), poly (methyltetramethylene glycol) and the like. These may be used alone or in combination of two or more.

The number average molecular weight of the long-chain polyol is preferably in the range of 1,000 to 5,000. By using a long-chain polyol having such a number average molecular weight, a golf ball made of the polyurethane composition excellent in various properties such as the above-mentioned resilience and productivity can be surely obtained. The number average molecular weight of the long-chain polyol is more preferably in the range of 1,500 to 4,000, and even more preferably in the range of 1,700 to 3,500.

The above-mentioned number average molecular weight is a number average molecular weight calculated based on the hydroxyl value measured in accordance with JIS-K1557 (hereinafter, the same applies).

As the chain extender, those used in the conventional techniques for polyurethane can be preferably used, and the chain extender is not particularly limited. In the present invention, a low molecular weight compound having two or more active hydrogen atoms capable of reacting with an isocyanate group and having a molecular weight of 2,000 or less can be used, and among them, a fat having 2 to 12 carbon atoms. Group diols can be preferably used. Specific examples thereof include 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol and the like. Among them, 1,4-butylene glycol can be preferably used.

As the polyisocyanate, those used in the conventional techniques for polyurethane can be preferably used, and there is no particular limitation. Specifically, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, naphthylene 1,5-diisocyanate, tetramethylxylene diisocyanate, hydrogenated 1 selected from the group consisting of xylylene diisocyanate, dicyclohexamethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate, 1,4-bis (isocyanatomethyl) cyclohexane, dimerate diisocyanate 1 Species or two or more species can be used. However, depending on the isocyanate type, it may be difficult to control the cross-linking reaction during injection molding.

Further, the compounding ratio of the active hydrogen atom: isocyanate group in the polyurethane forming reaction can be appropriately adjusted within a preferable range. Specifically, in producing polyurethane by reacting the above-mentioned long-chain polyol, polyisocyanate compound and chain extender, a polyisocyanate compound is used with respect to 1 mol of active hydrogen atoms contained in the long-chain polyol and the chain extender. It is preferable to use each component at a ratio of 0.95 to 1.05 mol of isocyanate groups contained in.

The method for producing polyurethane is not particularly limited, and it may be produced by either a prepolymer method or a one-shot method using a long-chain polyol, a chain extender and a polyisocyanate compound using a known urethanization reaction. good. Among them, it is preferable to carry out melt polymerization in the absence of a solvent, and it is particularly preferable to carry out melt polymerization by continuous melt polymerization using a multi-screw screw type extruder.

As the above-mentioned polyurethane, it is preferable to use a thermoplastic polyurethane material. As the thermoplastic polyurethane material, a commercially available product can be preferably used, and examples thereof include a trade name "Pandex" manufactured by DIC Cobestropolymer and a trade name "Resamine" manufactured by Dainichiseika Kogyo Co., Ltd. be able to.

Polyurea Polyurea is a resin composition mainly composed of a urea bond formed by the reaction of (i) isocyanate and (ii) amine terminal compound. This resin composition will be described in detail below.

(I) Isocyanate As the isocyanate, those used in the conventional techniques for polyurethane can be preferably used, and there is no particular limitation, and the same isocyanates as those described in the above polyurethane materials can be used.

(Ii) Amine-Terminated Compound The amine-terminated compound is a compound having an amino group at the end of the molecular chain, and in the present invention, the following long-chain polyamines and / or amine-based curing agents can be used.

A long-chain polyamine is an amine compound having two or more amino groups in the molecule capable of reacting with an isocyanate group and having a number average molecular weight of 1,000 to 5,000. In the present invention, the more preferable number average molecular weight is 1,500 to 4,000, and even more preferably 1,900 to 3,000. Specific examples of the long-chain polyamines include hydrocarbons having amine ends, polyethers having amine ends, polyesters having amine ends, polycarbonates having amine ends, polycaprolactones having amine ends, and mixtures thereof. However, it is not limited to these. These long-chain polyamines may be used alone or in combination of two or more.

On the other hand, the amine-based curing agent is an amine compound having two or more amino groups in the molecule capable of reacting with isocyanate groups and having a number average molecular weight of less than 1,000. In the present invention, the more preferred number average molecular weight is less than 800, more preferably less than 600. Specific examples of the amine-based curing agent include ethylenediamine, hexamethylenediamine, 1-methyl-2,6-cyclohexyldiamine, tetrahydroxypropyleneethylenediamine, 2,2,4- and 2,4,4-trimethyl-1, 6-Hexaminediamine, 4,4'-bis- (sec-butylamino) -dicyclohexylmethane, 1,4-bis- (sec-butylamino) -cyclohexane, 1,2-bis- (sec-butylamino)- Cyclohexane, derivative of 4,4'-bis- (sec-butylamino) -dicyclohexylmethane, 4,4'-dicyclohexylmethanediamine, 1,4-cyclohexane-bis- (methylamine), 1,3-cyclohexane-bis -(Methylamine), diethylene glycol di- (aminopropyl) ether, 2-methylpentamethylenediamine, diaminocyclohexane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, propylenediamine, 1,3-diaminopropane, dimethylaminopropylamine , Diethylaminopropylamine, dipropylenetriamine, imide-bis-propylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, isophoronediamine, 4,4'-methylenebis- (2-chloroaniline) , 3,5-dimethylthio-2,4-toluenediamine, 3,5-dimethylthio-2,6-toluenediamine, 3,5-diethylthio-2,4-toluenediamine, 3,5-diethylthio-2,6- Toluenediamine, 4,4'-bis- (sec-butylamino) -diphenylmethane and its derivatives, 1,4-bis- (sec-butylamino) -benzene, 1,2-bis- (sec-butylamino)- Benzene, N, N'-dialkylamino-diphenylmethane, N, N, N', N'-tetrakis (2-hydroxypropyl) ethylenediamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p -Aminobenzoate, 4,4'-methylenebis- (3-chloro-2,6-diethyleneaniline), 4,4'-methylenebis- (2,6-diethylaniline), m-phenylenediamine, p-phenylenediamine, And mixtures thereof, but not limited to these. These amine-based curing agents may be used alone or in combination of two or more.

(Iii) Polyurea Polyurea is not an essential component, but can further contain a polyol in addition to the above-mentioned components (i) and (ii). As the polyol, those used in the conventional techniques for polyurethane can be preferably used, and there is no particular limitation, but specific examples thereof include the long-chain polyols and / or polyol-based curing agents shown below. can.

As the long-chain polyol, any of those conventionally used in the technology related to polyurethane can be used and is not particularly limited, but for example, polyester polyol, polyether polyol, polycarbonate polyol, polyester polycarbonate polyol, polyolefin-based polyol. , Conjugate diene polymerization system polyol, castor oil type polyol, silicone type polyol, vinyl polymerization system polyol and the like. These long-chain polyols may be used alone or in combination of two or more.

The number average molecular weight of the long-chain polyol is preferably 1,000 to 5,000, more preferably 1,700 to 3,500. Within the range of this number average molecular weight, the resilience, productivity and the like are further excellent.

As the polyol-based curing agent, those used in the conventional techniques for polyurethane can be preferably used, and are not particularly limited. In the present invention, a low molecular weight compound having two or more active hydrogen atoms capable of reacting with an isocyanate group and having a molecular weight of less than 1,000 can be used, among which a fat having 2 to 12 carbon atoms can be used. Group diols can be preferably used. Specific examples thereof include 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol and the like. Among them, 1,4-butylene glycol can be preferably used. The preferred number average molecular weight of the polyol-based curing agent is less than 800, more preferably less than 600.

As the method for producing the polyurea, a known method can be adopted, and a known method such as a prepolymer method or a one-shot method may be appropriately selected.

Various additives can be further added to the resin composition as the resin component of polyurethane or polyurea, if necessary, and for example, pigments, inorganic fillers, dispersants, antioxidants, and light-resistant stabilizers. , Ultraviolet absorber, mold release agent and the like can be appropriately blended.

Next, the inner layer adjacent to the outermost layer "hereinafter, also simply referred to as" inner layer ". Will be explained. This inner layer is formed of a composition containing a compound having a functional group that reacts with isocyanate.

The inner layer adjacent to the outermost layer may be each layer of the cover or the core. That is, a known rubber composition or thermoplastic resin used in golf balls can be used as the main component in the inner layer. For example, ionomer resin, polyester elastomer, polyamide elastomer, polyolefin, polybutadiene rubber composition, and these. The modified product of the above can be used, and these main components may have a functional group that reacts with isocyanate, or may separately contain a compound having a functional group that reacts with isocyanate. For example, amines, polyols, alcohols, carboxylic acids, water and the like, specifically, trimethylolpropane, polytail and the like can be mentioned, and these can be selected and used without limitation, but the present invention is not limited to one. Alternatively, two or more types can be used. However, the inner layer does not contain polyurethane and polyurea as resin components.

The functional group that reacts with the above-mentioned isocyanate is not particularly limited, and examples thereof include a hydroxyl group, an amino group, and a carboxyl group, and one or a combination of two or more of these can be preferably used.

Various additives can be further added to the composition of the inner layer, if necessary, and for example, a pigment, an inorganic filler, a dispersant, an antioxidant, a light-resistant stabilizer, an ultraviolet absorber, and a release agent. Molds and the like can be appropriately blended.

Isocyanate derived from blocked isocyanate is present at the interface between the outermost layer and the inner layer. That is, in the present invention, the surface of the inner layer is treated with a treatment solution containing the following (i) and (ii) component (i) blocked isocyanate (ii) water or an organic solvent, and then the surface of the treated inner layer is treated. By molding the outermost layer, an isocyanate derived from blocked isocyanate is provided at the interface between the outermost layer and the inner layer.

Here, to explain the above-mentioned treatment solution, ordinary isocyanates (that is, monomeric MDI, HDI, TDI, etc.) have a high reaction rate and react with water in the air to be deactivated, so that water management is difficult. , Blocked isocyanate is a compound in which the isocyanate group is masked with a blocking agent to suppress the reactivity. When heated, the blocking agent is dissociated and the isocyanate group is regenerated, and the activated isocyanate group reacts with the isocyanate. Reacts with a compound having Further, since the blocked isocyanate does not react in the resin composition and is stable until it is heated, there is an advantage that the quality is stable and the workability is good.

The type of isocyanate in the blocked isocyanate is not particularly limited, but for example, tolylen-2,6-diisocyanate, tolylen-2,4-diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylenepolyphenylpolyisocyanate, 1, 5-Diisocyanatonaphthalene, isophorone diisocyanate (including isomer mixture), dicyclohexylmethane-4,4'-diisocyanate, hexamethylene-1,6-diisocyanate, m-xylylene diisocyanate, hydrogenated xylylene diisocyanate, trizine diisocyanate , Norbornene diisocyanate, and derivatives thereof, and prepolymers formed from the above isocyanate compounds.

As the polyisocyanate, it is preferable to use an aromatic polyisocyanate, and in particular, polymethylene polyphenyl polyisocyanate (polymeric MDI) is preferably used. That is, it is preferable to use an aromatic polyisocyanate in the present invention because the resin physical properties of the outermost layer polyurethane or polyurea are toughened. Further, the polypeptide MDI has a larger number of isocyanate groups in the molecule than the HDI and the monomeric MDI, so that the effect of improving the scratch resistance due to the formation of crosslinks is large, and since it is liquid at room temperature, it is excellent in handleability. It is preferably adopted from the point of view.

Specific examples of the blocked isocyanate blocking agent include an oxime-based blocking agent, a phenol-based blocking agent, a lactam-based blocking agent, an alcohol-based blocking agent, an active methylene-based blocking agent, an amine-based blocking agent, and a pyrazole-based blocking agent. Examples thereof include heavy sulfite-based blocking agents, imidazole-based blocking agents, carbonic acid and ammonia blocking agents.

Various catalysts may be used for the above-mentioned treatment solution, if necessary. As the catalyst, those used in the conventional techniques for polyurethane or polyurea can be preferably used, and are not particularly limited.

Further, the above-mentioned treatment solution may be dispersed in a solvent if necessary, and as the solvent to be used, a generally used known solvent can be used without particular limitation, and specifically, water. , Acetone, NMP, DPM, ethyl acetate, n-butyl acetate and the like are preferably used. It is most preferable to use water as a solvent from the viewpoint of dispersibility and environmental safety.

Commercially available products can be used as the blocked isocyanate, for example, "Coronate" manufactured by Tosoh Corporation, "Duranate" manufactured by Asahi Kasei Corporation, "Karenzu MOI-BM" manufactured by Showa Denko Corporation, and "Barnock" manufactured by DIC Corporation. , And HDI blocked isocyanate manufactured by Baxenden.

As a method for treating the above-mentioned treatment solution, a method of applying the treatment solution to the surface of the inner layer by brush coating, roller coating, spraying or the like, coating with an air spray or a roll coater, or a sphere covering the core or each layer is described above. Examples thereof include a method of directly immersing in a treatment solution, but the immersing method is particularly preferably used from the viewpoint of productivity and adhesion efficiency to the inner layer surface. This treatment time can be appropriately selected according to the treatment method used, but in the dipping method, it is preferably 120 minutes or less, more preferably 60 minutes or less, still more preferably 30 minutes or less, and most preferably 30 minutes or less. Within 5 seconds to 10 minutes. If the above treatment time is too long, the solvent of the treatment solution may be excessively impregnated inside the inner layer, and volatile components may be generated when coating the outermost layer cover due to insufficient drying, which may cause a problem. In addition, the longer processing time increases the lead time of production, which is not very preferable from the viewpoint of productivity. From the viewpoint of productivity, the temperature during the above treatment is preferably maintained at a temperature at which a stable solution state can be maintained, specifically, preferably 10 to 55 ° C, more preferably. It is 20 to 40 ° C, more preferably 15 to 30 ° C. If the treatment temperature is too low, the solution viscosity is high and excessive adhesion to the inner layer surface, and if the treatment temperature is too high, the solvent volatilizes and the solution concentration cannot be stably maintained, resulting in adhesion to the inner layer surface. The amount may be stable and uncontrollable. In addition, when an ionomer-based material is used for the inner layer, it may cause changes in physical properties. By performing the treatment within the above-mentioned suitable range of treatment time and treatment temperature, desired physical properties can be obtained without impairing productivity.

The amount of the treatment solution used depends on the treatment method of the treatment solution, but the amount of the polyisocyanate compound adhered to the inner layer after the surface treatment is appropriately adjusted according to the mass of the entire golf ball and desired physical properties. It can be preferably 0.03 to 0.50 g, more preferably 0.05 to 0.45 g, still more preferably 0.07 to 0.40 g per ball. If it is out of this range, the isocyanate component may not be sufficiently adhered and the desired physical properties may not be obtained.

The surface of the inner layer treated with the above-mentioned treatment solution can be improved in adhesion and scratch resistance, which are the effects of the present invention, by adding a drying step and a heating step described later.

In the production method of the present invention, the surface of the inner layer is treated with the above-mentioned treatment solution, but when the step of cleaning the surface of the inner layer (spherical surface of the inner layer-coated sphere) and the step of polishing are included. Blocked isocyanate can be dispersed in water used in this washing step or polishing treatment and used as a treatment solution. In this case, since the treatment with the treatment solution can be performed at the same time as the cleaning or polishing treatment, there are advantages in terms of shortening the process and work efficiency.

Regarding the production method of the present invention, the method for forming the inner layer described above is not particularly limited, but a known method can be adopted. For example, a material for forming an inner layer is injected around the core. A molding method or a method of preparing a pair of hemispherical shell-shaped half cups in advance with a material for forming an inner layer, wrapping the core with these half cups, and pressurizing and heating at 140 to 180 ° C. for 2 to 10 minutes is adopted. can do. Further, as a method of molding the outermost layer, for example, the outermost layer can be molded by injecting a resin material for the outermost layer onto the surface of the inner layer treated with the above-mentioned treatment solution. In this case, the molding temperature varies depending on the type of polyurethane material or the like used, but is usually in the range of 150 to 270 ° C. Further, in the production method of the present invention, by molding at a temperature higher than the temperature at which the blocking agent of the blocked isocyanate adhering to the inner layer surface is dissociated, the blocking agent is generated by the heat applied by the molten resin adhering to the inner layer surface during molding. Dissociated and activated isocyanate groups react with compounds having functional groups that react with isocyanates in the inner layer to form three-dimensional crosslinks, etc., and at the same time, with functional groups that react with isocyanates in urethane or polyurea in the outermost layer. By forming a dimensional crosslink, the adhesion between the inner layer and the outermost layer can be improved. Further, by cross-linking the outermost layer polyurethane or polyurea with an isocyanate activated from the inside, the outermost layer becomes stronger and scratch resistance can be improved.

Further, it is preferable to provide a step for heating the golf ball including the outermost layer after molding the outermost layer. This heating step is provided for effectively advancing the cross-linking reaction between the thermoplastic material of polyurethane or polyurea and the polyisocyanate compound, and for improving and stabilizing the physical properties and quality. However, since the reaction of blocked isocyanate proceeds even at the temperature applied during injection molding, it is not always necessary to provide a heating step.

In this heating step, a method for advancing the crosslinking reaction in the presence of heat, pressure, and a catalyst can be appropriately selected. Specifically, the heating temperature is preferably 20 to 150 ° C., more preferably 40 to 40 to. The temperature is 130 ° C., more preferably 60 to 120 ° C., most preferably 70 to 110 ° C., and the heating time is preferably 0.5 to 120 minutes, more preferably 1 to 60 minutes, still more preferably 1.5 to 30 minutes. It is preferable to carry out the heat treatment at an appropriate temperature and time for minutes, most preferably 2 to 20 minutes.

In one or more layers of covers constituting the golf ball of the present invention, the outermost layer surface hardness (also referred to as ball surface hardness) after the above treatment is a durometer D-type hardness, preferably 30 to 70, more preferably 33 to 33. 65. If the hardness of the outermost layer of the cover is too low, the amount of spin when hit by the driver increases and the flight distance may decrease. Further, if the hardness of the outermost layer of the cover is too high, the feeling may be deteriorated and the resilience performance and durability performance of the urethane material may be inferior.

The thickness of the outermost layer of the cover can be in the range of 0.1 to 5.0 mm, preferably 0.3 to 3.0 mm, and more preferably 0.5 to 2.0 mm. .. When the cover is formed in a multi-layer structure of two or more layers, the thickness of the intermediate layer is not particularly limited, but can be in the range of 0.1 to 5.0 mm, preferably 0.3. It is ~ 3.0 mm, more preferably 0.5 ~ 2.0 mm.

The golf ball of the present invention is preferably formed to have a diameter and weight in accordance with the Rules of Golf, and is usually formed to have a diameter of 42.67 mm or more and a weight of 45.93 g or less, but has a diameter of 42.67 to 42.67 to. It is preferably 42.9 mm.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 16, Comparative Examples 1 and 2]
A core having a diameter of 38.6 mm was prepared by preparing and vulcanizing a rubber composition for a core common to all the examples according to the formulation shown in Table 1.

The details of the core material are as follows.
-"Cis-1,4-polybutadiene" manufactured by JSR Corporation, product name "BR01"
・ "Zinc acrylate" manufactured by Nippon Catalyst Co., Ltd. ・ "Zinc oxide" manufactured by Sakai Chemical Industry Co., Ltd. ・ "Barium sulfate" manufactured by Sakai Chemical Industry Co., Ltd. )
・ "Organic peroxide (1)" dicumyl peroxide, trade name "Park Mill D" (manufactured by NOF CORPORATION)
-"Organic peroxide (2)" 1,1-di (tert-butylperoxy) A mixture of cyclohexane and silica, trade name "Perhexa C-40" (manufactured by NOF CORPORATION)
・ "Zinc stearate" manufactured by NOF CORPORATION

Next, a resin material for the intermediate layer, which is common to all the examples, was blended. The intermediate layer referred to here corresponds to the inner layer adjacent to the outermost layer of the cover in the present invention. This intermediate layer resin material is a material in which 50 parts by mass of "Himilan 1605", 50 parts by mass of "Himilan 1706", and 1.1 parts by mass of trimethylolpropane are blended. The above product name "Himilan" is an ionomer resin manufactured by Mitsui DuPont Chemical Co., Ltd. This resin material was injection-molded around the core having a diameter of 38.6 mm obtained above to produce an intermediate layer-coated sphere having an intermediate layer having a thickness of 1.25 mm.

Next, a treated solution prepared by dissolving the blocked isocyanate or the blocked isocyanate shown in Table 2 below with water or acetone was prepared, and the treated solution was applied to the surface of the intermediate layer-coated sphere of each example. As the treatment conditions for the treatment solution on the surface of the intermediate layer-coated sphere, an amount of solution that sufficiently immerses the entire surface of the intermediate layer-coated sphere is placed in a container in which the entire surface of the intermediate-layer-coated sphere is sufficiently immersed, and the intermediate layer-coated sphere is sufficiently immersed. Was immersed. The treatment method is a golf ball intermediate in which the treatment is performed at a treatment solution temperature of 23 ° C. and a immersion time in the treatment solution for 10 seconds, and surface treatment is performed on an intermediate layer-coated sphere having a coating amount of 0.1 g (weight increase after drying). Got

・ "Isocyanate 1"
Polymeric MDI "Sumijour" manufactured by Sumika Bayer Urethane Co., Ltd.
・ "Blocked isocyanate 1"
HDI blocked isocyanate "Aqua" manufactured by Baxenden
・ "Blocked isocyanates 2-4"
Both are block polyisocyanates "Bionate" manufactured by Daiei Sangyo Co., Ltd.

Next, in order to form the outermost layer on the surface of the intermediate layer treated with the above-mentioned treatment solution, a resin material for the outermost layer was injection-molded around the intermediate layer-coated sphere to have a thickness of 0.8 mm. A three-piece golf ball having a cover layer (outermost layer) was produced. At this time, common dimples were formed on the cover surfaces of the Examples and Comparative Examples, although not particularly shown.

The resin material for the outermost layer is an ether type thermoplastic polyurethane manufactured by DIC Cobestropolymer [trade names "Pandex T8283" and "T8290" (mass ratio of the former to the latter 60.0: 40. 0)] A resin material containing 7.5 parts by mass of 4,4'-diphenylmethane diisocyanate as an isocyanate compound with respect to 100 parts by mass.

For each of the obtained example and comparative golf balls, the amount of deflection of the ball, the scratch resistance of the outermost layer by the guillotine test, and the adhesion between the outermost layer and the inner layer were evaluated as follows. These results are shown in Table 2.

Ball diameter (outer diameter)
At a temperature of 23.9 ± 1 ° C., 15 parts without any dimples were measured, the average value was taken as the measured value of one ball, and the average value of five balls to be measured was obtained.

Deflection amount of the ball The ball was placed on a hard plate, and the amount of deflection (mm) from the state where the initial load of 98 N (10 kgf) was applied to the time when the final load of 1275 N (130 kgf) was applied was measured. The above-mentioned deflection amounts are all measured values after the temperature is adjusted to 23.9 ° C.

Guillotine test Using the guillotine test device 1 shown in FIG. 1, the golf ball G is set in the semicircular mold 2, and the test blade 1a having a load of 1.9 kg and a cutting edge R = 1.0 mm is set from a height of 500 mm. It was dropped freely, and the scratch resistance of the outermost layer was visually evaluated according to the following criteria. The test blade was adjusted so that it would fall vertically between the top of the golf ball and the equator.
[evaluation]
◎ ・ ・ ・ There are hit marks, but there are no scratches.
○ ・ ・ ・ Scratched but not torn.
× ・ ・ ・ Scratched and torn.

Adhesion As shown in FIG. 2, when p1 is a plane having a distance of 2 mm from the center of the golf ball 10 and p2 is a plane point-symmetrical to p1 with respect to the center of the ball, it is between p1 and p2. The adhesion strength between the outermost layer 30 and the intermediate layer 20 was measured at the ball portion s1. A cut T is made in the outermost layer 30 of the ball at the portion where the outermost layer 30 and p1 overlap, and the portion where the outermost layer 30 and p2 overlap, and the outermost layer 30 other than s1 is peeled off. Next, a cut T was made in the outermost layer 30 so as to be perpendicular to p1 and p2, and the outermost layer 30 was peeled off from the intermediate layer 20 by about 20 mm from the cut to provide a gripping margin to obtain a test piece. With reference to JIS K6256 "Adhesion test method for vulcanized rubber and thermoplastic rubber", the moving speed of the gripping jig was set to 50 mm / min, and the tensile strength was measured every 0.1 mm. The tensile strength for about 100 mm was measured for one test piece, and these values were taken as the adhesion force (unit: N). The test piece obtained above is used, and the grip margin provided on the outermost layer 30 is held by a grip jig. The test piece fixing jig is such that the test piece can rotate while maintaining its center position, and the outermost layer 30 wound around the intermediate layer 20 is peeled off without slack as the gripping jig moves. Can be done.

From the results of Tables 3 and 4, the following can be considered from the experimental results of Tables 3 and 4 above in Examples 1 to 16.
Comparative Example 1 was an example in which nothing was treated on the inner layer, and the adhesion between the inner layer and the outermost layer was not sufficient, and the guillotine test evaluation and the adhesion were low.
Comparative Example 2 was an example in which the inner layer was surface-treated with an active isocyanate solution, and the isocyanate reacted with the moisture in the air and was inactivated, so that the guillotine test evaluation and the adhesion were low. On the other hand, Examples 1 to 16 are examples in which the inner layer is surface-treated with a blocked isocyanate solution, and it can be seen that the guillotine test evaluation and adhesion are improved as compared with Comparative Examples 1 and 2.

Claims (13)

In a golf ball having a core and a cover covering the core, the outermost layer of the cover is formed of a resin composition containing polyurethane or polyurea as a main component, and the inner layer adjacent to the outermost layer reacts with isocyanate. A golf ball formed of a composition containing a compound having a functional group, and having an isocyanate derived from blocked isocyanate present at the interface between the outermost layer and the inner layer. The golf ball according to claim 1, wherein the functional group that reacts with the isocyanate is one or a combination of two or more selected from a hydroxyl group, an amino group and a carboxyl group. The golf ball according to claim 1 or 2, wherein the isocyanate derived from the blocked isocyanate is an aromatic polyisocyanate. The golf ball according to claim 3, wherein the isocyanate derived from the blocked isocyanate is a polypeptide MDI. The blocking isocyanate blocking agent is an oxime-based blocking agent, a phenol-based blocking agent, a lactam-based blocking agent, an alcohol-based blocking agent, an active methylene-based blocking agent, an amine-based blocking agent, a pyrazole-based blocking agent, and a heavy sulfite-based blocking agent. The golf ball according to any one of claims 1 to 4, which is selected from the group of imidazole-based blocking agents, carbonic acid and ammonia blocking agents. In the method of manufacturing a golf ball whose core is covered with a cover,
The step (1) of molding the inner layer adjacent to the outermost layer of the cover with a composition containing a compound having a functional group that reacts with isocyanate.
The step (2) of treating the surface of the inner layer with a treatment solution containing the following (i) and (ii) components (i) blocked isocyanate (ii) water or an organic solvent.
A step (3) of forming the outermost layer on the surface of the inner layer treated by the above step (2) by molding the outermost layer with a resin composition containing polyurethane or polyurea as a main component.
A method for manufacturing a golf ball, which comprises. The method for producing a golf ball according to claim 6, wherein the functional group that reacts with the isocyanate is one or a combination of two or more selected from a hydroxyl group, an amino group and a carboxyl group. The method for producing a golf ball according to claim 6 or 7, wherein the isocyanate derived from the blocked isocyanate is an aromatic polyisocyanate. The method for producing a golf ball according to claim 8, wherein the isocyanate derived from the blocked isocyanate is a polypeptide MDI. The blocking isocyanate blocking agent is an oxime-based blocking agent, a phenol-based blocking agent, a lactam-based blocking agent, an alcohol-based blocking agent, an active methylene-based blocking agent, an amine-based blocking agent, a pyrazole-based blocking agent, and a heavy sulfite-based blocking agent. The method for producing a golf ball according to any one of claims 6 to 9, which is selected from the group of imidazole-based blocking agents, carbonic acid and ammonia blocking agents. The method for producing a golf ball according to any one of claims 6 to 10, further comprising a step (4) for heating the golf ball including the outermost layer after molding the outermost layer. The method for manufacturing a golf ball according to claim 11, wherein the heating temperature in the step (4) is 40 to 120 ° C. The method for producing a golf ball according to claim 11 or 12, wherein the heating time in the step (4) is 5 to 120 minutes.

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