JPH0767987A - Racket frame and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a racket frame a working process of which is simple, voids and pin holes are a little on the surface, strength is large, and weight is light. CONSTITUTION:Continuous fiber is wound for covering on a plastic tube core material 2 and fixed together with a yoke core material part 3 to a metal mold. Inner pressure is applied to a tube, a material capable of forming a cross- linked polyamino-amide resin is injected in a state where the inside pressure of the metal mold is reduced, and is cured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to tennis, squash,
The present invention relates to a racket used for ball games such as badminton, and particularly to a racket frame molded with fiber reinforced resin.

[0002]

2. Description of the Related Art Conventionally, a racket frame is generally formed of a fiber reinforced resin, and the manufacturing method thereof is roughly classified into an external pressure method and an internal pressure method. In the external pressure method, a reinforcing fiber is wound around a core material, a thermosetting resin is impregnated into the core material, the temperature is slightly heated to a B stage, and then the core material is placed in a mold and cured by heating. In the internal pressure method, the reinforcing fibers are impregnated with a thermosetting resin in advance, a prepreg sheet is made, cut into appropriate sizes, and the directions are changed while paying attention to the fiber directions, and then combined into a mandrel. It is wound around the covered tube, then the mandrel is pulled out, the tube and the prepreg sheet wound around the tube are put into a mold, and the tube is heated and cured while being pressurized. Further, in recent years, regarding these manufacturing methods, a tube core material wound with continuous fibers is fixed to a mold, and a material capable of forming a polyamide resin while applying an internal pressure in the tube or a material capable of molding a dicyclopentadiene resin is provided. Injection,
A method of curing has been proposed (Japanese Patent Laid-Open No. 1-3156).
82, JP-A-3-176083, JP-A-4-35701.
0, Japanese Patent Publication No. 5-33645).

[0003]

However, the conventional racket frame forming method described above has the following problems.
That is, the external pressure method has a problem that the process requires labor and the racket frame becomes heavy because the core material is used. Further, in the internal pressure method, since the prepreg sheet is wound in advance and cured in the mold, air remains, and pinholes and voids are easily formed on the frame surface. Furthermore, when a material capable of forming a polyamide resin is used, it takes a long time to cure, workability is poor, and the strength of the molded racket frame is insufficient, and a material capable of forming a dicyclopentadiene resin. When using, the resin raw material has a bad odor,
Since the odor remains after molding, it is not suitable for sports equipment applications, and it is not well compatible with continuous fibers, and the strength of the fibers cannot be fully drawn out.

[0004]

In view of the above-mentioned drawbacks of the conventional method, the present invention provides a method for manufacturing a racket frame having a short curing time, few voids and pinholes on the surface, and high strength, and a method for manufacturing the same. The racket frame manufactured is provided. That is, according to the present invention, a continuous fiber is coated and wound around a plastic tube core material, fixed to a mold together with a yoke core material part, and a crosslinked polyaminoamide resin is generated in a state where internal pressure is applied inside the tube to reduce the pressure inside the mold. The present invention relates to a method for manufacturing a racket frame, which comprises injecting a curable material and curing the material, and a racket frame manufactured by the manufacturing method. The plastic tube core material used in the present invention may be any as long as it has heat resistance and molding strength, for example, 6-nylon,
Examples of the thermoplastic resin include 6,6-nylon, polyester elastomer, polyethylene terephthalate, and fluororesin. The thickness of the tube is preferably 20 to 100 μ. If it is thinner than 20 μ, it may be difficult to maintain the strength during molding, and if it is thicker than 100 μ, it may affect the weight of the racket frame, and it may be difficult for the racket frame to easily bulge when an internal pressure is applied. The fold width of the tube is
Although it is determined by the design of the cross section of the racket frame, one having a width of about one half of the maximum length of the circumference of the hollow portion of the cross section or slightly wider than that is preferably used. When the plastic tube is made of fluororesin, it can be easily pulled out after molding, which is preferable in terms of weight reduction of the racket frame.

The continuous fibers used in the present invention include, for example, glass fibers, carbon fibers, ceramic fibers, boron fibers, tungsten fibers, molybdenum fibers, beryllium fibers, stainless fibers, aluminum fibers and other inorganic fibers, polyamide fibers, polyester fibers. Examples of the synthetic fiber include fibers, polyvinyl alcohol fibers, and high-strength polyethylene fibers. These are woven, roving, mat or 2
The shape of a shaft or a triaxial blade may be used and used alone or in combination. The fiber may have any length as long as it can be wound around the tube. A carbon fiber or a blade made of carbon fiber and glass fiber is preferably used. The content of continuous fibers can be arbitrarily selected from the viscosity of a material capable of molding a polyaminoamide resin (hereinafter referred to as a resin stock solution), the type and shape of continuous fibers, but is usually about 40.
It is about 80% by weight. As the yoke core portion of the present invention, a suitable core material such as polyurethane foam, polymethacrylimide foam, polyethylene terephthalate foam, etc., in which the above continuous fibers are wound, is used. A polyurethane foam in which a carbon fiber or a blade made of carbon fiber and a glass fiber is wound is preferably used. The mold used in the present invention may be made of a metal such as aluminum or steel, or a resin such as an epoxy resin. The mold includes an upper mold and a lower mold, and a resin injection port and a mold for a parting line. The one provided with a decompression port inside and a connection port with a plastic tube is used. The resin injection port is preferably provided on the head side of the racket frame, and the decompression port in the mold and the connection port with the tube are preferably provided on the grip end side of the racket frame.

As a material capable of forming the crosslinked polyaminoamide resin used in the present invention, a resin obtained by reacting a bisoxazoline compound and an aromatic amine compound in the presence of a catalyst can be mentioned. Examples of the bisoxazoline compound include 2,2 ′-(1,3-phenylene) bis-2-oxazoline (abbreviated as 1,3-PBO), 2,
2 '-(1,4-phenylene) bis-2-oxazoline and the like can be mentioned. Examples of the aromatic amine compound include 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and 2,2'-bis [4- (4-aminophenoxy) phenyl. ] Propane etc. are mentioned. Examples of the catalyst include N-octyl bromide, 1,4-dibromobutane, methyl iodide, ethyl p-toluenesulfonate, ethyl 2-bromopropionate, 2-bromopropionic acid, and aniline hydrobromide. To be Known additives such as a stabilizer, an internal mold release agent, a colorant, a flame retardant, and a filler may be added to these materials in order to meet the required characteristics. In addition, epoxy modifiers may be added to these materials. Examples of the epoxy modifier include bisphenol A diglycidyl ether, phenol novolac diglycidyl ether, and diglycidyl phthalate. The epoxy modifier has a low melting temperature and can lower the temperature at the time of injecting the resin stock solution. The viscosity of the resin stock solution is preferably relatively low in order to obtain a resin having a high continuous fiber content, and usually about 5 to 100 cps is preferably used.

The method for manufacturing the racket frame of the present invention is as follows. Cut a plastic tube with one end closed to a specified length, cover it with an auxiliary rod having a cross-sectional area close to the cross-sectional area of the hollow part of the racket frame, and on the outside of it, weave, roving, mat or blade etc. The continuous fiber is covered and wound to form a core material. After pulling out the auxiliary rod, it is fixed at a predetermined position of a mold heated to 80 to 150 ° C. A separately manufactured yoke core member may be fixed at a predetermined position, and if necessary, a reinforcing material may be partially used.
At this time, it is important to make the clearance between the core material and the mold uniform. In particular, the resin stock solution easily accumulates at both ends of the yoke part or the grip end part, so that the clearance between the core material and the mold is made as close as possible. The tube opening is connected to the tip of a pipe adapted to exert air pressure. After the fixing of the position of the material is completed, the upper mold is lowered and made airtight, and then an internal pressure of about 0.1 to 3 kg / cm ² is applied to the tube to reduce the pressure in the mold to 1 to 50 mmHg. Resin stock solution at 90-130 ℃
Prepare in a heated tank, open the cock, and pour into the mold. At this time, the resin stock solution tank may be pressurized.
The pressure is preferably lower than the internal pressure of the tube by about 0.1 kg / cm ² or more. Further, in order to prevent curing shrinkage, the tube internal pressure may be further increased by about 0.1 to ² kg / cm ² when the injection of the resin stock solution is completed. The mold closing time depends on the type of the resin stock solution used, the amount of catalyst, and the mold temperature, but is usually about 2 to 20 minutes. In this way, the resin raw material is cured, and then the mold is opened and the racket frame is taken out.

[0008]

The racket frame manufacturing method of the present invention eliminates the drawbacks of the conventional methods, and can provide a racket frame having a simple working process, few surface voids and pinholes, and high strength.

[0009]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1 An example will be described with reference to the drawings. FIG. 1 shows a state in which a core material portion 2 in which a continuous fiber is coated and wound around a plastic tube is fixed to a lower mold 6 of a mold for molding the racket frame of the present invention. The core part 2 is a tube of 6-nylon having a thickness of 50 μ, closed at one end, and coated with three layers of blades woven by unidirectional carbon fibers.
It was fixed to the lower mold 6 heated to 5 ° C. Next, a polyurethane foam having a specific gravity of 0.3 was coated with a carbon fiber blade, and a yoke core member 3 made by combining glass cloth was fixed to the lower mold 6. The tube opening is connected to the tip of a pipe 5 adapted to apply air pressure, and the resin injection port 1 and the pipe 4 for reducing the pressure inside the mold are connected to the lower mold 6.
Connected to. The resin raw materials were 1,3-PBO, 4,4′-diaminodiphenylmethane and Epicoat 807 (epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) in a molar ratio of 4:
Mix at a ratio of 7: 5, heat and melt to 95 ° C in the tank.
I kept it at. Immediately before injection, the resin raw material 1 is used as a catalyst.
To 100 parts, 4 parts of 1,4-dibromobutane and 1 part of ethyl p-toluenesulfonate were added and mixed well. Then, the upper mold was lowered to close the mold to make it airtight. Immediately, an air pressure of 0.5 kg / cm ² was applied to the tube, and a vacuum line was opened in the mold to reduce the pressure to about 10 mmHg. Next, the resin stock solution injection port cock was opened to inject the resin raw material. The resin raw material reached the pressure reducing pipe after about 15 seconds. At that point, the vacuum line was closed, and the internal pressure in the tube was left as it was for about 15 minutes. During that time, part of the undiluted resin solution remaining in the pipe 1 of the resin injection port entered the mold so as to compensate for the curing shrinkage inside the mold. After 15 minutes, the mold was opened and the cured racket frame was taken out. The surface of the racket frame was clean except for a small void at the grip end. The content of continuous fibers in the hitting portion of this racket frame was 59% by weight.

Example 2 As a core material of the core portion 2, a fluororesin (PTF) having one end closed
Using a tube having a thickness of 50 μm of E), 1,3-PBO and 4,4′-diaminodiphenylmethane were mixed at a molar ratio of 6: 5 as a resin raw material, and the resin raw material 100 was used as a catalyst immediately before injection. The same as in Example 1 was used except that 2 parts of 1,4-dibromobutane was added to the parts. The mold temperature was set to 130 ° C., the mold was opened 6 minutes after the injection of the resin raw material, and the racket frame was taken out. The inside of the tube was decompressed, and the fluororesin tube was removed from the wall surface of the tube and pulled out. The void of the racket frame was hardly seen. The content of continuous fibers in the hitting portion of this racket frame was 65% by weight.

[Brief description of drawings]

FIG. 1 shows a state in which a material is fixed to a mold (lower mold).

[Explanation of symbols]

1-Resin injection port 2-Core part 3-Yoke core part 4-Pipe for pressure reduction 5-Pipe for pressurization 6-Lower mold

Claims (9)

[Claims] 1. A plastic tube core material is coated and wound with continuous fibers, fixed to a mold together with a yoke core part, an internal pressure is applied to the inside of the tube, and a crosslinked polyaminoamide resin is applied under reduced pressure inside the mold. A method for manufacturing a racket frame, which comprises injecting a material that can be generated and curing the material. 2. The method for producing a racket frame according to claim 1, wherein an epoxy modifier is added to a material capable of forming a crosslinked polyaminoamide resin. 3. The method of manufacturing a racket frame according to claim 1, wherein the internal pressure in the tube is 0.1 to 3 kg / cm ² . 4. The pressure inside the mold is reduced to 1 to 50 mmHg.
A method for manufacturing the racket frame described. 5. The method of manufacturing a racket frame according to claim 1, wherein the continuous fiber is a carbon fiber or a blade made of carbon fiber and glass fiber. 6. The method of manufacturing a racket frame according to claim 1, wherein the core material of the yoke core portion is a polyurethane foam. 7. The method of manufacturing a racket frame according to claim 1, wherein a fluororesin tube is used as the plastic tube core material, and the fluororesin tube is removed after curing. 8. The method of manufacturing a racket frame according to claim 1, wherein the content of the continuous fibers is 40 to 80% by weight. 9. A racket frame manufactured by the manufacturing method according to claim 1.