JPH0415702B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a golf club, and more particularly, to an improvement of a golf club generally referred to as a wood golf club, which is equipped with a club head mainly made of fiber-reinforced plastic. [Prior Art] The club head of a golf club called "Utsudo" has traditionally been manufactured using persimmon wood as the main material, but recently, club heads manufactured using fiber-reinforced plastic as the main material have been developed and used. I'm getting used to it. Conventionally, as the core of this type of club head, a foamable synthetic resin such as a hard urethane foam with a low specific gravity or a hollow molded piece of hard plastic has been used for the purpose of reducing the weight of the head. However, the former, that is, a core made of foamable synthetic resin such as hard urethane foam, has a low compressive strength and cannot sufficiently apply high compression molding pressure during club head molding. As a result, not only are voids likely to occur in the reinforcing layer of the head outer shell, which is made of molded fiber-reinforced plastic, but the core also has a low breaking strength, causing the golf club to disintegrate over long periods of use. I was afraid. In addition, if the latter, that is, a hollow molded product made of hard plastic, is used as the core, not only will voids occur, but because it is hollow,
It has been difficult to obtain a satisfactory club head due to a decrease in ball flight distance and directionality, which are important characteristics of a golf club, and poor feel at impact, such as impact sound. Furthermore, the majority of club heads made primarily of fiber-reinforced plastic are molded by compression molding, but it is extremely difficult to apply press pressure evenly over the entire molded product during molding. For this reason, voids and nests are likely to form locally in the fiber-reinforced plastic club head outer shell reinforcing layer of the molded product, and the compressive strength becomes directional.
This has been a cause of decreasing the hardness and durability of the club head. As a solution to this problem, internal pressure is applied externally during molding using a fluid such as liquid using a bladder, etc. to harden the molding, and then the fluid is discharged outside, and the core material is later buried in the space where this discharge remains. Alternatively, a method of molding the club head by injection hardening is also used, but this method requires complicated molding processes and equipment, and also imposes restrictions on the structural design of the club head. [Object of the Invention] The present invention was developed as a result of studies to solve the above-mentioned problems. Therefore, an object of the present invention is to prevent voids and nests from forming in the reinforcing layer of the head outer shell made of fiber-reinforced plastic, and to prevent the formation of reinforcing fibers in the head outer shell reinforcing layer, which is made of fiber-reinforced plastic, by devising the core of a club head made mainly of fiber-reinforced plastic. It is an object of the present invention to provide an excellent golf club which can improve the quality and workability of the club head such as the content of the golf ball and the uniformity of its strength, as well as the flight distance of the golf ball and the feel when hitting the golf ball. [Structure of the Invention] That is, the gist of the present invention is that the core of the club head is composed of a rubber-like elastic material having a Shore D height of 40 to 70 and containing cis 1,4-polybutadiene rubber and zinc diacrylate as main components. It is. Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings. 1 and 2 show a golf club according to an embodiment of the present invention. FIG. 1 is a perspective view showing the main part, that is, the club head, and FIG.
It is a cross-sectional explanatory diagram taken along the line A-A. In the figure, E indicates a golf club according to an embodiment of the present invention, in which a club shaft S is provided with a grip (not shown) at one end, and a system is provided at the other end.
1.4-Carbon fiber and/or carbon fibers are placed around the core body 11, which is made of a rubber-like elastic body with a Shore D hardness of 40 to 70 and whose main components are polybutadiene rubber and zinc diacrylate.
Alternatively, it is constructed by attaching a club head 10 integrally provided with a fiber-reinforced plastic layer 12 (head outer shell reinforcing layer 12) mainly made of glass fiber-reinforced plastic. The above-mentioned club head 10 is constructed by pre-impregnating reinforcing fibers such as carbon fibers constituting the head outer shell reinforcing layer 12 with an uncured resin around the core body 11 made of the rubber-like elastic body. The club head is covered with strands and/or mat and/or fabric, and then placed in a club head mold and compressed and heated to be cured. In the present invention, since a rubber-like elastic body having appropriate hardness and high impact resilience is used as the core body 11, the core body 11 is appropriately elastically deformed by the press pressure during the above-mentioned molding, and the core body 11 is Repulsion pressure (compression molding pressure) generated by moderate elastic deformation is applied almost uniformly to the head outer shell reinforcing layer 12. As a result, voids and nests can be prevented from forming.
It is possible to obtain the head outer shell reinforcing layer 12 having uniform strength over the entire circumference. Therefore, the rubber-like elastic body constituting the above-mentioned core 11 has a Shore D hardness of 40 to 40 and is mainly composed of cis 1.4-polybutadiene rubber and zinc diacrylate.
It is preferably 70, and more preferably 50-60. This is because if the shore D hardness of the rubber-like elastic body constituting the core body 11 is less than 40, the elastic deformation of the core body 11 becomes uneven due to the press pressure during molding described above, and the elastic deformation of the core body 11 is biased toward the head outer shell reinforcing layer 12. The meat is produced, and the balance, which is an important requirement for the club head, is disrupted.
This is because, on the one hand, the quality of the golf club deteriorates, and on the other hand, there is a risk that voids and cavities may be generated in the head outer shell reinforcing layer 12 due to the inability to obtain uniform rebound pressure (compression molding pressure) during the above-mentioned molding. , if the Shore D hardness of the rubber-like elastic body exceeds 70, the core 1
Since a repulsion pressure of 1 (compression molding pressure) cannot be obtained, a uniform repulsion pressure cannot be applied to the head outer shell reinforcing layer 12, and as a result, the above-mentioned effect of preventing the generation of voids and nests cannot be obtained. It is from. In order to improve the adhesion between the core 11 made of a rubber-like elastic material and the head outer shell reinforcing layer 12, the surface of the molded core 11 is buffed to make the surface of the core 11 rough. or,
An adhesive may be applied to the surface of the core body 11. Further, the above-described golf club of the present invention is particularly suitable for a fairway golf club, which is generally called a wood golf club, in which the club head has a large mass relative to its volume, and the weight of the core body 11 is It can be increased or decreased by adjusting the specific gravity of the rubber-like elastic body that constitutes this. In addition, in the figure, 13 is a sole plate. Examples will be described below. Example 1 100 parts (parts by weight) of cis-1.4-polybutadiene,
Add 45 parts of zinc diacrylate, 14 parts of zinc oxide, and 2.5 parts of peroxide (Perhexa V: manufactured by NOF Corporation), mix using a mixing roll, and fill this into a club head core mold. 160
Pressure molding was carried out at .degree. C. for 20 minutes to obtain a club head core having a specific gravity of 1.18 g/ ^cm.sup.3 and a Shore D hardness of 58. After buffing the surface of this club head core to roughen it and modify its shape, this core is then molded into a sheet of carbon fiber that has been pre-impregnated with an appropriate amount of polyester resin.
The compound (SMC), sole plate, etc. were placed in a club head mold for compression molding, pressurized, and heated to harden to create a club head. As a result of cutting the club head obtained in this way and visually observing the state of its cross section, it was found that there were almost no voids or nests in the reinforcing layer of the head outer shell made of carbon fiber reinforced plastic, and there were no uneven thickness or pieces of the core. I didn't even come close. Furthermore, when we adjusted this club head to a No. 4 fairway and actually tried hitting a golf ball, we found that the ball flight distance, ball direction, and hitting sound were much better than the conventional club head mentioned above. It was hot. Example 2 and Comparative Examples 1 to 4 Regarding Example 2, Comparative Example 1, and Comparative Example 4,
The rubber-like elastic material for the core of the club head was adjusted according to the compounding specifications shown in Table 1, mixed using a mixing roll, and then filled into a mold for the club head core. Pressure molded at 160℃ for 20 minutes, and in the case of Comparative Examples 1 to 4, at 150℃
Pressure molding was performed for 30 minutes to obtain club head cores having the physical properties shown in Table 1. Each of these cores was treated in the same manner as in the first embodiment described above, and then the club head was made into a No. 4 fairway. The condition of the cut surfaces of these club heads and the test hitting results are as shown in Table 1.

【table】

〔Effect of the invention〕

As described above, the present invention has the following effects by constructing the core of the club head from a rubber-like elastic body having a Shore D hardness of 40 to 70 and mainly composed of cis 1.4-polybutadiene rubber and zinc diacrylate. play. That is, (1) Since the core body is made of a rubber-like elastic body having the above-mentioned structure, it is possible to impart appropriate and uniform compressive deformation to the core body by press pressure during club head molding. As a result, it is possible to apply substantially uniform compression molding pressure to the entire fiber-reinforced plastic outer shell reinforcing layer, which greatly reduces the occurrence of voids and nests in the fiber-reinforced plastic outer shell reinforcing layer. , it is possible to obtain an outer shell reinforcing layer with uniform strength. Furthermore, deformation during compression can be made uniform, uneven thickness of the outer shell reinforcing layer can be prevented, and the weight balance of the club head can also be improved. Furthermore, the generally used molding method, such as applying internal pressure from the outside for the purpose of preventing voids, can be simplified, productivity can be improved, and the degree of freedom in structural design of the club head can also be improved. (2) Unlike conventional cores made of foamable synthetic resins such as hard urethane foam, there is no risk of the core collapsing after long-term use, and the durability of the golf club can be greatly improved. (3) Furthermore, in the golf club of the present invention, since the core is made of substantially the same material as the core of a general two-piece golf ball, the ball and club head resonate when the ball is hit, increasing rebound resilience. As a result, the flight distance increases, and the feeling when hitting the ball improves.

[Brief explanation of drawings]

1 and 2 show a golf club according to an embodiment of the present invention. FIG. 1 is a perspective view showing the main part, that is, the club head, and FIG.
It is a cross-sectional explanatory diagram taken along the line A-A. 10...Club head, 11...Core body.

Claims (1)

[Claims] 1. A golf club head comprising a club shaft equipped with a grip at one end and a club head made mainly of fiber-reinforced plastic attached to the other end. 1. A golf club comprising a rubber-like elastic material having a Shore D hardness of 40 to 70.