JP3154690B2 - Method for manufacturing multi-piece solid golf ball - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multi-piece solid golf ball capable of mass-producing a multilayer core having two or more layers without eccentricity without using a large-scale apparatus.

[0002]

2. Description of the Related Art A solid golf ball is a golf ball which is not a thread-wound golf ball and comprises a rubber integrally formed core and a cover which covers the core. In recent years, various improvements have been made to improve the performance of golf balls, and a method of forming a core of a solid golf ball into a multilayer structure of two or more layers has also been proposed.

[0003] From the viewpoint of the performance of golf balls, it is an excellent method to form a core of a solid golf ball into a multilayer structure, but from a manufacturing viewpoint, a rubber layer is formed concentrically without causing eccentricity. It is very difficult. The following three methods have already been proposed as a manufacturing process of a multilayer core. (a) When the (N + 1) -th layer is provided, a portion inside the (N-th) layer is separately vulcanized and formed, and a movable hold pin or the like is placed at a predetermined position in the mold of the (N + 1) -th layer. Fixed with
A method of injecting a material for forming the (N + 1) layer by an injection molding machine or a transfer molding machine, pulling out the hold pin at an appropriate timing, and vulcanizing and molding as it is, (b) forming the (N + 1) th layer in a hemispherical shape Semi-vulcanized into a hemispherical shell shape using a concave shape and a hemispherical convex shape, or heated for a certain time so as not to shrink in an unvulcanized state, formed into a hemispherical shell shape, and after removing the hemispherical convex shape, the hemisphere With the shell-shaped outer layer attached to the hemispherical concave shape, set the N-th layer that had been separately vulcanized,
Vulcanizing press molding method, so-called core method, method (c)
In (b), a method of using an unvulcanized sheet without forming the outer layer into a hemispherical shell has been used.

[0004] These methods are disclosed, for example, in JP-A-63-105774.
JP-A No. 2-228978 (Method (a))
(a)), JP-A-6-218077 (methods (a), (b) and
(c)). However, these methods sacrifice workability in order to reduce the displacement of the Nth layer portion of the core, and are not suitable for manufacturing a golf ball having an actual multilayer structure.

[0005] For example, in the method (a), the N-th layer is held by a movable hold pin in a mold of an injection molding machine or a transfer molding machine, and then the pin is pulled out together with the injection of an outer layer material. In addition, the structure of the mold is very complicated, resulting in an increase in cost, and the number of presses per press is reduced due to the limit of pressure at the time of injection, which is not suitable for mass production. Further, clearance adjustment and management of the movable pin and the mold are complicated, and there are problems such as poor sliding if the pin is narrow and protrusion of rubber if the pin is wide.

In the above method (b), although the drawbacks of (a) such as a small number of presses in one press and a problem of a mold are overcome, the outer layer is once formed into a hemispherical shell shape. Occasionally, although the hemispherical shell-shaped outer layer must adhere to the hemispherical concave shape for forming the outer layer, it must adhere to the hemispherical convex shape and need to be transferred to the hemispherical concave shape. So it could not be adopted for mass production.

In the method (c), the same problem remains, except that the preparation for forming the hemispherical shell outer layer in (b) is changed to a sheet shape. As described above, the conventional methods (a) to (c) have a fatal defect in mass production.

Therefore, as a manufacturing method capable of mass production without causing surface dents and poor interlayer adhesion while reducing eccentricity, (d) when forming the (N + 1) th layer, vulcanization molding to a desired shape is performed. A method has been proposed in which a mold having a shape different from that of the mold is used, and the N-th layer is wrapped and preformed in an unvulcanized state. Since this method includes a molding step in an unvulcanized state, shrinkage occurs due to the residual stress of rubber after molding in a negative direction, and peeling from two bonded portions, so-called opening, resulting in eccentricity and deterioration in workability. Was invited. In order to prevent these, it is necessary to finely adjust the pressing time and pressure according to the change of the rubber material, but this is also not a sufficient measure, and it can absorb the variation of the previous process and the variation of the rubber material Was not reached. It is also possible to enhance the adhesive strength with an adhesive, but this increases the number of steps and
There is a problem that it also becomes a factor of variation.

As a method of further improvement, it is proposed to (e) integrally vulcanize and form a semi-vulcanized or vulcanized hemispherical shell-shaped (N + 1) layer with an unvulcanized N-th layer interposed therebetween. However, if the upper and lower (N + 1) layers are not accurately positioned, the N-th layer becomes a protruding core. To accurately sandwich the N-th layer with the (N + 1) layer, the uncured N-th layer It is necessary to eliminate the variation in the shape of the device, and there has been a problem that the device used becomes large-scale.

[0010]

SUMMARY OF THE INVENTION The problems in the conventional method of manufacturing a multi-piece solid golf ball as described above are solved. In particular, in the method (e), the N-th core can be formed without using a large-scale apparatus. It is an object of the present invention to provide a method for manufacturing a multi-piece solid golf ball, in which a layer can be integrally formed with a (N + 1) th layer without eccentricity and with high accuracy.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object. As a result, in the step of manufacturing a multilayer core, a hemispherical shell-shaped core was formed on the upper die of a press die.
By fixing the (N + 1) layer by magnetic force using a jig and coating the (N + 1) layer on the Nth layer of the core, a large number of multilayer cores without eccentricity can be produced without using a large-scale apparatus. It has been found that it can be produced, and the present invention has been completed.

That is, the present invention is a method for producing a multi-piece solid golf ball comprising a core comprising two or more layers and a cover formed on the core, wherein the step of producing the core comprises the steps of: When the hemispherical (N + 1) th layer is coated on the Nth layer, a jig is used at a runner portion between the hemispherical (N + 1) th layers using a jig to form the (N) nonmagnetic material.
+1) The present invention relates to a method for manufacturing a multi-piece solid golf ball, wherein the layer is fixed between a press die and a jig by magnetic force.

The present invention also provides a method for producing a multi-piece solid golf ball comprising a core comprising two or more rubber composition layers and a cover formed on the core.
In the step of manufacturing the core, a hemispherical shell-like second core of the core is provided.
When the (N + 1) layer is coated on the Nth layer, the
A multi-piece wherein a non-magnetic (N + 1) -th layer is fixed by magnetic force between a vulcanizing press mold and a jig using a jig in a runner portion between the (N + 1) layers. The present invention relates to a method for manufacturing a solid golf ball.

Further, the present invention relates to a method for producing a rubber composition comprising the steps of: (i) when the Nth layer of the core is in an unvulcanized state, wherein the (N + 1) th layer is half-cured. (Ii) When the Nth layer of the core is in a vulcanized state, the (N + 1) th layer is in a semi-vulcanized state.

The method for manufacturing a multi-piece solid golf ball of the present invention will be described in more detail with reference to FIGS. For the sake of simplicity, the core inner layer (Nth
Layer) and a core outer layer ((N +
1) a two-layer core (N)
= 1) is covered with a cover. FIG. 1 is a schematic sectional view of one embodiment of the golf ball of the present invention. FIG.
FIG. 1 is a schematic cross-sectional view of one embodiment of a vulcanizing press mold for explaining a golf ball manufacturing method of the present invention. FIG. 3 is a schematic cross-sectional view of one embodiment of a mold for forming the inner layer (N-th layer) of the core used in the golf ball of the present invention. FIG. 4 is an outer layer ((N + 1) th layer) of a core used in the golf ball of the present invention.
It is an outline sectional view of one mode of a metallic mold. FIG.
Outer layer of core (No. (N + 1)) used in golf ball of the present invention
FIG. 4 is a plan view illustrating a state in which the layer (a) is fixed to a mold on a vulcanizing press. As shown in FIG. 1, the golf ball of the present invention has a core formed by forming an outer core layer (2) on an inner core layer (1).
(4) A cover (3) is formed thereon.

The inner core layer (1) and the outer core layer (2) of the golf ball of the present invention are formed of the same material, and will be described at once. Both are base rubber, co-crosslinking agent,
It is composed of a rubber composition containing an organic peroxide, a filler and the like. As the base rubber, natural rubber and / or synthetic rubber conventionally used for solid golf balls is used, and particularly so-called high cis having at least 40% or more, preferably 80% or more of cis-1,4-bonds. Polybutadiene rubber is preferred. The polybutadiene rubber may include, as desired, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, ethylene-propylene-diene rubber (E
PDM) and the like.

Examples of the co-crosslinking agent include metal salts of α, β-unsaturated carboxylic acids, in particular, zinc salts of α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms such as acrylic acid or methacrylic acid.
A monovalent or divalent metal salt such as a magnesium salt is exemplified, and zinc acrylate which imparts high resilience is preferable. The compounding amount is 5 to 40 parts by weight, preferably 10 to 35 parts by weight, based on 100 parts by weight of the base rubber in the core inner layer (1), and 5 to 40 parts by weight, preferably in the core outer layer (2). Is 10-35
Parts by weight. If the content is more than 40 parts by weight in the inner core layer (1) or more than 40 parts by weight in the outer core layer (2), the core becomes too hard and the shot feeling is deteriorated. If the amount is less than 10 parts by weight in the inner core layer (1) or less than 10 parts by weight in the outer core layer (2), the resilience becomes poor and the flight distance is reduced.

Organic peroxides act as crosslinkers or hardeners, for example, dicumyl peroxide, 1,1-
Bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butylperoxide, Mil peroxide is preferred. Compounding amount is base rubber
0.1 to 5 parts by weight, preferably 0.3 to 3 parts per 100 parts by weight
Parts by weight. If the amount is less than 0.1 part by weight, it becomes too soft, the rebound is deteriorated, and the flight distance is reduced. If it exceeds 5 parts by weight, the ball becomes too hard, and the shot feeling becomes poor.

The filler may be any one as long as it is usually compounded in the core of a golf ball. For example, an inorganic salt (specifically,
Zinc oxide, barium sulfate, calcium carbonate), high specific gravity metal powder (for example, tungsten powder, molybdenum powder, etc.) and mixtures thereof. The compounding amount is 5 to 60 parts by weight, preferably 10 to 100 parts by weight of the base rubber.
5555 parts by weight. If the amount is less than 5 parts by weight, the weight of the core is reduced, and as a result, the weight of the ball is also reduced.
If it exceeds 60 parts by weight, the weight of the core becomes heavy, and as a result, the weight of the ball becomes too heavy.

Further, the core inner layer and the core outer layer of the golf ball of the present invention may appropriately contain an antioxidant or a peptizer, and other components which can be generally used for producing a core of a solid golf ball. The anti-aging agent is a base rubber.
0.2 to 0.5 part by weight is preferable for 100 parts by weight.

The core inner layer (1) of the present invention is obtained by mixing the above-mentioned rubber composition with a commonly used mixer and kneading with a kneader such as a roll. Subsequently, the kneaded material is extruded as a plug in an unvulcanized state by a usual method. Core inner layer
When (1) is in a vulcanized state, the unvulcanized plug is replaced with upper and lower metal having a hemispherical cavity as shown in FIG. Using a mold, vulcanizing press is performed at 140 to 170 ° C. for 40 to 15 minutes to form a spherical core inner layer having a diameter of 30 to 40 mm.

Next, the core outer layer (2) corresponds to the core inner layer (1) described above.
A rubber composition similar to that described above is mixed and kneaded, and a core mold (15) having a core portion (14) and a hemispheric mold (16) having a hemispherical cavity as shown in FIG. At 150-170 ° C
A vulcanization press is performed for 15 to 7 minutes to produce a vulcanized hemispherical shell outer layer (13) connected by a runner (12). When the core outer layer is in a semi-vulcanized state, the above pressing conditions are set at 130 to 150 ° C.
Except for 10 to 5 minutes, the same as in the vulcanized state,
A hemispherical shell outer layer having a thickness of ３3 mm is prepared. By using the method of the present invention, a thin layer having a thickness of about 0.5 mm can be formed.

The hemispherical shell outer layer connected by the runner obtained as described above is set in a vulcanizing press upper mold (10) in which a magnet (5) is embedded as shown in FIG. The runner (7) between the core outer layers (8) is fixed by the magnetic force of the magnet (5) using a comb-like iron jig (6). Regarding the magnet (5), the dimensions are not particularly limited, but a magnetic force sufficient to fix the hemispherical shell outer layer (8) to the vulcanizing press upper mold (10) by an iron jig (6), that is, 3 to 150 kgf in total, preferably
What is necessary is just to have 30-70kgf. FIG. 5 is a plan view showing a state in which the hemispherical shell outer layer (19) connected by the runner (18) as described above is fixed to a mold on a vulcanizing press using a comb-shaped iron jig (17). It is a representation.

As shown in FIG. 2, the mold under the vulcanizing press (11)
, A similar hemispherical shell outer layer (8) is set, an unvulcanized plug (9) is placed therein, and the mold is clamped. It is preferable that the operation is performed at a very low speed from the position where the plug (9) comes into contact with the outer layer (8) of the hemispherical shell-like core set in the upper mold (10) of the vulcanizing press so as not to displace the plug. The iron jig (6) may be pulled out during the operation at a low speed, or may be removed after vulcanization by clamping the mold while keeping it. After clamping, vulcanization is performed at 140 to 170 ° C. for 40 to 15 minutes to form a two-layer core (4).

When a vulcanized spherical core inner layer is used instead of the unvulcanized plug (9), the outer diameter of the core portion (14) in FIG. 4 is the same as the outer diameter of the spherical inner layer core, The outer layer of the hemispherical shell core must be in a semi-vulcanized state. That is, when an unvulcanized plug is used, even if the outer layer of the hemispherical shell core is vulcanized, it can be sufficiently molded integrally. However, when a vulcanized spherical inner core is used, the hemispherical shell outer layer covering the core is not integrally molded unless it is in a semi-vulcanized state. That is, when the Nth layer is in an unvulcanized state, the (N + 1) th layer is in a semi-vulcanized or vulcanized state, and when the Nth layer is in a vulcanized state, the (N + 1) th layer is in a vulcanized state.
The layers need to be in a semi-vulcanized state.

Here, the semi-vulcanized state refers to a state in which the rubber composition is not completely vulcanized, but the vulcanization is temporarily stopped before the crosslinking reaction is completed. When the semi-vulcanized product is heated again, crosslinking proceeds further, and the crosslinking reaction can be completed. The conditions for semi-vulcanization are based on the vulcanization time
It is about 1/10 to 1/3. For example, when complete vulcanization is performed at 150 ° C. for 30 minutes, vulcanization is performed at 150 ° C. for about 5 minutes. In the case of the outer layer of the hemispherical shell core used in the present invention, complete vulcanization is usually 14
Since it is carried out at 0 to 170 ° C for 40 to 15 minutes, 1/1 of its vulcanization time
If it is stopped at 10 to 1/3, it will be in a semi-vulcanized state. If the vulcanized spherical core inner layer is put inside, and the formed semi-vulcanized hemispherical shell core outer layer is joined to complete the vulcanization,
A two-layer core (4) is formed.

When manufacturing a three-layer core (N = 2),
The two-layer core prepared as described above is used as an inner core layer (Nth layer), and a hemispherical shell outer layer ((N + 1) th layer) is coated thereon by the same method as described above. Make it. In this case, since the two-layer core (N-th layer) is in a vulcanized state, the third layer, that is, the (N + 1) -th layer must be in a semi-vulcanized state. Further, when a core having four or more layers is produced, the above method can be repeated.

Also, as described above, the vulcanizing press upper mold (10)
The jig (6) itself may be made of a magnetic material instead of burying the magnet (5). The magnetic material here is generally called a ferromagnetic material, and is not particularly limited as long as it shows ferromagnetism in the vulcanization temperature range (140 to 170 ° C.) or lower of the rubber composition. Further, the magnet or jig buried in the mold may be used as an electromagnet so that the outer layer (8) of the hemispherical shell-like core becomes a magnetic material only when it is fixed to the mold (10) on the vulcanizing press.

By using the manufacturing method of the present invention, even when the Nth layer or the (N + 1) th layer of the core is not a rubber as described above, for example, when the core is made of a thermoplastic resin or the like, the core can be easily formed. Can be manufactured.

The cover (3) is covered on the core (4) having a two-layer structure obtained as described above. The cover of the present invention is made of a thermoplastic resin, particularly an α-olefin and a carbon number of 3 to 3.
An ionomer resin obtained by neutralizing a part of the carboxylic acid in a copolymer of eight α, β-unsaturated carboxylic acids with a metal ion, or a mixture thereof is used. As the α-olefin in the ionomer resin, ethylene and propylene are preferable, and as the α, β-unsaturated carboxylic acid, acrylic acid, methacrylic acid and the like are preferable. Further, as the metal ions to be neutralized, alkali metal ions such as Na ion, K ion and Li ion; divalent metal ions such as Zn ion, Ca ion and Mg ion; trivalent metal ions such as Al ion; Nd ions and the like; and mixtures thereof, of which Na ions, Zn ions, and Li ions are often used because of their resilience, durability and the like. Specific examples of the ionomer resin include, but are not limited to, Himilan 1557, 1605, 1652, 1705, 1706, 1707,
1855, 1856 (Mitsui DuPont Polychemical), Surlyn
AD8511, Surlyn AD8512 (Dupont), IOTEC 701
0, 8000 (manufactured by Exxon) and the like.

In the present invention, in addition to the above-mentioned resin as a main component, if necessary,
Fillers such as barium sulfate and coloring agents such as titanium dioxide,
Other additives, such as dispersants, antioxidants, ultraviolet absorbers, light stabilizers and fluorescent materials or fluorescent brighteners,
Although it may be contained within a range that does not impair the desired properties of the golf ball cover, usually, the amount of the coloring agent is 0.
5 to 5 parts by weight are preferred.

The cover layer of the present invention can be formed by a generally known method used for forming a cover of a golf ball, and is not particularly limited. The cover composition is preliminarily formed into a hemispherical shell-like half shell, and two cores are used to wrap the core and pressure-formed at 130 to 170 ° C. for 1 to 5 minutes, or the cover composition is directly cored. A method of wrapping the core by injection molding may be used. In the case of the cover forming method, an injection molding method is preferable from the viewpoint of workability and production efficiency. The thickness of the cover is 1-4 mm, preferably 1.3-2.7 mm. When it is smaller than 1 mm, the repulsive force of the core is not utilized, and when it is repeatedly hit, there is a disadvantage that the cover is easily cracked. When it is larger than 4 mm, the shot feeling is deteriorated. Further, at the time of molding the cover, many depressions called dimples are formed on the surface as necessary. The golf ball of the present invention is usually put on the market after being subjected to a paint finish, a marking stamp, or the like, in order to enhance aesthetic appearance and commercial value.

The present invention can provide a method of manufacturing a multi-piece solid golf ball capable of mass-producing a multilayer core having two or more layers without eccentricity without using a large-scale apparatus.

[0034]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Preparation of Unvulcanized Plug for Inner Core The rubber composition having the composition shown in Table 1 below was mixed and kneaded, and an unvulcanized plug of 30 g was prepared through an extruder.

Preparation of Core Outer Layer The same rubber composition as shown in Table 1 was mixed and kneaded with the unvulcanized plug, and the mixture was kneaded at 150 ° C. using a mold having a core portion as shown in FIG. For 5 minutes to produce a semi-vulcanized hemispherical shell outer layer having a thickness of 1.4 mm. Each cavity is connected by a runner.

[0037]

[Table 1] Type Parts by weight BR01 100 Zinc acrylate 25 Zinc oxide 22.3 Dicumyl peroxide 1

Fabrication of a Two-Layer Core (Example) A hemispherical shell outer layer connected by the runners obtained as described above was attached to a metal plate portion having a diameter of 12 mm and a magnetic force of 5 kgf as shown in FIG. Was set in the vulcanizing press upper mold (10) in which was embedded, and the runner (7) part of the core outer layer (8) was fixed with a comb-shaped iron jig (6) passing between the cavities. . A hemispherical shell outer layer (8) connected by a runner (7) similar to the above
The unvulcanized plug (9) obtained as described above is put in the mold and the mold is clamped.The upper end of the unvulcanized plug (9) has a vulcanizing press upper mold (10). From the position in contact with the outer layer (8) of the hemispherical shell-shaped core set at a very low speed, completely clamp the mold and perform vulcanization at 152 ° C for 20 minutes to obtain a 39.1 mm 2
A layer core was made. The working time of the two-layer core manufacturing process from setting of the hemispherical shell outer layer (8) to the mold (10) on the vulcanizing press to demolding was 5 minutes.

(Comparative Example) Using the same unvulcanized plug and hemispherical shell outer layer as those used in the example, the hemispherical shell outer layer was not fixed to the upper mold of the vulcanizing press with an iron jig. Except for this, a two-layer core having a diameter of 39.1 mm was produced in the same manner as in the example. In this method, it is necessary to manually adjust the core outer layer so as not to be displaced and eccentric, and the working time of the manufacturing process of the two-layer core is one hour.

From the above results, it was found that the metal plate had a diameter of 12
The example in which the core outer layer was set in a vulcanizing press upper mold in which a magnet having a magnetic force of 5 kgf was embedded and fixed with a comb-shaped iron jig passing between the cavities was 1 hour in the comparative example in which the magnet was not fixed. The required work time was greatly reduced to 5 minutes.

[0041]

According to the present invention, it is possible to mass-produce a multilayer core having two or more layers without using a large-scale laminating apparatus and without causing eccentricity or deterioration in workability. A method of manufacturing a solid golf ball can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of the golf ball of the present invention.

FIG. 2 is a schematic cross-sectional view of one embodiment of a vulcanizing press mold for explaining a method of manufacturing a golf ball of the present invention.

FIG. 3 is a schematic cross-sectional view of one embodiment of a mold for forming an inner layer (N-th layer) of a core used in the golf ball of the present invention.

FIG. 4 is a schematic cross-sectional view of one embodiment of a mold for molding an outer layer ((N + 1) th layer) of a core used in the golf ball of the present invention.

FIG. 5 is a plan view illustrating a state in which an outer layer ((N + 1) th layer) of a core used in the golf ball of the present invention is fixed to an upper mold in a vulcanizing press.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Core inner layer 2 ... Core outer layer 3 ... Cover 4 ... Core 5 ... Magnet 6, 17 ... Iron jig 7, 12, 18 ... Runner 8, 13, 19 ... Hemispherical shell outer layer 9 ... Unvulcanized plug 10 ... Upper mold for vulcanizing press 11… Lower mold for vulcanizing press 14… Core part 15… Core mold 16… Hemispherical mold

Claims (6)

(57) [Claims] 1. A method for manufacturing a multi-piece solid golf ball comprising a core comprising two or more layers and a cover formed on the core, wherein in the step of producing the core, a hemispherical shell-like shape of the core is provided. When the (N + 1) th layer is coated on the Nth layer, the jig is used to press the (N + 1) th layer, which is a nonmagnetic material, using a jig in a runner portion between the hemispherical shell-shaped (N + 1) th layers. A method for manufacturing a multi-piece solid golf ball, wherein the method is fixed by magnetic force between a mold and a jig. 2. The method for manufacturing a multi-piece solid golf ball according to claim 1, wherein the fixing is performed by using a press die having a magnet embedded therein and an iron jig. 3. The method of manufacturing a multi-piece solid golf ball according to claim 1, wherein the fixing is performed by using a jig as a magnetic material. 4. The method according to claim 1, wherein the core comprises two or more layers of a rubber composition. 5. The N-th layer of the core is in an unvulcanized state,
5. The method according to claim 4, wherein the (N + 1) th layer is in a semi-vulcanized or vulcanized state. 6. The method according to claim 4, wherein the Nth layer of the core is in a vulcanized state, and the (N + 1) th layer is in a semi-vulcanized state.