JPH0226517Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the core material used to improve the mechanical strength of wooden tennis racket frames. A wooden product, such as a wooden tennis racket frame, has the structure shown in FIGS. 1A and 1B. This wooden tennis racket frame 10 uses a center member 11 as a reinforcing material for reinforcing mechanical strength. As shown in FIG. 1B, the center member 11 is sandwiched between wooden frames 12 and 12' on both sides thereof. The wooden frames 12, 12' are each made of three layers of laminated plywood as shown. and,
Decorative FRP boards (fiber-reinforced plastic boards) 13
is attached. Incidentally, in the wooden tennis racket frame 10 having the above structure, a carbon cloth epoxy laminate has conventionally been used as the center member 11. In order to adhesively laminate this conventional core material 11 with the wooden frames 12, 12' as shown in FIGS. 1A and 1B, it was necessary to use an epoxy adhesive with excellent adhesive properties. For this reason, due to the characteristics of the epoxy adhesive, it is necessary to heat and pressure mold at approximately 130°C for 30 minutes during adhesive molding, which causes the problem of deformation of the wooden frame due to the high temperature. Ta. In addition, since it takes a long time for this adhesive molding, even if the wooden frames 12, 12' are laminated in advance, the adhesive molding takes at least 40 minutes, resulting in a long working time. Ta. The present invention was developed in view of the above circumstances, and it is possible to bond and mold wooden components using a urea resin adhesive that hardens at a lower temperature than epoxy adhesives, achieving a good reinforcing effect. To provide a center material for a wooden tennis racket frame, which can prevent deformation of a wooden product and reduce adhesive molding work time. That is, the present invention provides a base material layer made of carbon cloth or a group of carbon fibers aligned in one direction in a central material that is sandwiched around a wooden frame and used to reinforce the mechanical strength of the wooden tennis racket frame. and bleached Bakelite base paper laminated on both sides of the base material layer. In the present invention, when a group of carbon fibers aligned in one direction is used as a base material layer, a resin prepreg of carbon fibers in which these fiber groups are bonded with resin is used. Further, the base material layer and the bleached Bakelite base paper are laminated via an adhesive, and in this case, it is desirable to adhesively laminate the base material layer and the Bakelite base paper as a prepreg of an adhesive resin. The following is a second example of applying the reinforcing material for wooden products according to the present invention to the center material for a wooden tennis racket frame.
This will be explained in detail with reference to the drawings. FIG. 2 is a sectional view showing a wooden tennis racket center member 20 according to an embodiment of the present invention. In the figure, 21 is a base material layer made of carbon cloth. Bakelite base papers 22 and 22' are adhesively laminated on the front and back surfaces of the base layer 21, respectively, using an epoxy adhesive. The surfaces of the Bakelite base papers 2, 2' are made rough by sanding. According to the core material 20 of the above embodiment, since the Bakelite base paper 22, 22' has good adhesion, it can be attached to the wooden frames 12, 22' as shown in FIGS. 1A and 1B.
When bonding and laminating the adhesive layer 2' by sanderch, it is possible to use a urea resin adhesive which exhibits adhesive ability at a lower temperature and in a shorter time than an epoxy adhesive. As a result, deformation of the wooden frame after adhesive molding can be prevented and manufacturing time can be significantly shortened.
Furthermore, in the core material 20 of the above embodiment, the surfaces of the Bakelite base papers 22, 22' are made rough by sanding, so that adhesion properties are improved. Incidentally, since a tennis racket frame is required to have mechanical strength in the plane direction and not so much strength in the thickness direction, the base material layer 21 of the above embodiment may be one in which carbon fibers are aligned in one direction instead of carbon cloth. may also be used. Next, an example of manufacturing the center member 20 of the above embodiment and an example of manufacturing a wooden tennis racket frame using this center member 20 will be described. [Manufacture of core material] (i) Using a bleached Bakelite base paper having the characteristics shown in (a) below, bleaching is carried out by applying 70 to 80 g/m ² of the epoxy resin composite material shown in (b) below to the Bakelite base paper. We produced epoxy prepreg using Bakelite base paper. (a) Bleached Bakelite base paper Thickness: 0.13 tmm Density: 0.47 Airtightness: 6 to 7 seconds (b) Epoxy resin composition Epicoat 1001 90 parts by weight (Epoxy resin manufactured by Ciel Chemical Co., Ltd.) Hexahydrophthalic anhydride 30 parts by weight (Curing agent) Benzylmethylamine 0.75 〃 (Curing agent) (ii) Add 200 g/m ² of the epoxy resin composition of (b) to 0.27 mm thick Torayca cloth (trade name of carbon cloth manufactured by Toyo Rayon Co., Ltd.) I applied it and made an epoxy prepreg for trading card cloth. (iii) On both sides of the trading card cloth prepreg obtained in (ii),
Two sheets of the Bakelite base paper prepreg obtained in (i) were placed on each sheet, and pressed at 160℃ to 180℃ for 10 minutes.
Adhesive lamination was carried out by heating and pressing at ~30 Kg/cm ² for 30 minutes. Subsequently, both sides of this laminate were polished with a sander to obtain the core material 20 of the embodiment shown in FIG. [Manufacture of wooden tennis racket frame] (i) The core material 20 obtained as described above is
Cut to the width of the wooden frames 12 and 12' in figures A and B,
After applying a urea resin adhesive to this ribbon-shaped center material, it was sandwiched between wooden frames 12 and 12' as shown in FIGS. 1A and 1B. In addition, FRP plates 13 and 13' were placed on this sandwich laminate board in the same manner as in FIG. However, this
The FRP boards 13 and 13' were prepared by adhesively laminating the bleached Bakelite base paper prepreg used for the core material 20 on one side, and applying a urea resin adhesive to the bleached Bakelite base paper side. (ii) Next, the laminate assembled as described above was heated and pressed for 10 minutes at a temperature of 100° C. and a pressure of 10 kg/cm ² for contact molding to produce a wooden tennis racket frame similar to that shown in FIG. 1. The tennis racket frame obtained had sufficient adhesive strength and mechanical strength. As mentioned above, the core material 2 in the embodiment of FIG.
0, the adhesive molding when manufacturing the wooden tennis rackets shown in Figure 1 A and B can be reduced from the conventional 130°C to 30°C.
It was possible to carry out the process at a low temperature of 100°C, and the time required for adhesive molding was also significantly shortened from the conventional 40 minutes to 10 minutes. As a result, defects in product deformation were completely eliminated, and productivity was significantly improved. In addition, the core material 20 using a group of carbon fibers aligned in one direction as the base material layer 21 is made of commercially available trading card epoxy prepreg with a thickness of 0.25 mm instead of the trading card cloth epoxy prepreg in the above manufacturing example. It can be similarly manufactured using one-way drawing alignment, and the same effect as above can be obtained. As described in detail above, according to the present invention, it is possible to bond and mold wooden components at low temperatures and in a short time using a urea resin adhesive, and a good reinforcing effect can be achieved. It is possible to provide a wooden tennis racket frame center material that has remarkable effects such as preventing deformation defects and improving productivity.

[Brief explanation of the drawing]

Fig. 1A is a plan view of a wooden tennis racket frame, Fig. 1B is a sectional view taken along line B-B in Fig. 1A, and Fig. 2 shows the reinforcing material according to the present invention applied to the center material for a wooden tennis racket frame. FIG. 3 is a cross-sectional view showing one embodiment. 10 ...Wooden tennis racket frame, 12, 12'
...Wooden frame, 13,13'...FRP for surface decoration
Plate, 20 ...Central material, 21...Base material layer, 22,2
2'...Bleached Bakelite base paper.

Claims (1)

[Scope of utility model registration request] A base material layer made of carbon cloth or a group of carbon fibers aligned in one direction, which is a core material arranged in a sandwiched manner on a wooden frame to reinforce the mechanical strength of the wooden tennis racket frame;
A center material for a wooden tennis racket frame, comprising bleached Bakelite base paper laminated on both sides of the base material layer.