JPH06286010A - Wrapping tape for frp molding and production of frp - Google Patents

Abstract

PURPOSE:To obtain a wrapping tape having sufficient strength though relatively thin-made, developing good releasability to a thermosetting resin without using a release agent and withstanding sufficient molding pressure. CONSTITUTION:A wrapping tape for molding and producing FRP has layered constitution consisting of a first layer composed of a heatshrinkable film having easy releasability to a thermosetting resin and a second layer composed of a heat-shrinkable film having Young's modulus higher than that of the first layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrapping tape for FRP (fiber reinforced plastic) molding and a method for producing FRP using the wrapping tape.

[0002]

2. Description of the Related Art As a method for molding FRP (for example, carbon fiber reinforced plastic: CFRP), a sheet winding method, a filament winding method and the like are known. These methods are used for molding cylindrical objects such as golf club shafts and fishing rods. In these methods, the prepreg of the reinforcing fiber is wound around the mandrel, the wrapping tape is wrapped around the outside of the prepreg, and the prepreg is heated and cured in that state, and then the mandrel is removed and the wrapping tape is removed. This wrapping tape fixes the prepreg so that the prepreg does not separate from the mandrel when the resin is cured, and applies a molding pressure to the prepreg by utilizing the heat shrinkability of the tape.

Conventionally, as the wrapping tape, a polyester film (for example, biaxially oriented polyethylene terephthalate film) or a polypropylene film (for example, uniaxially oriented or biaxially oriented polypropylene film) is used.
Is used.

[0004]

However, in the case of a wrapping tape made of a polyester film, the strength required for the wrapping tape can be easily obtained, and a high molding pressure is applied to the prepreg due to the heat shrinkage stress of the resin itself when the resin is heated and cured. Although it is possible to give the above, since the releasability to the resin (thermosetting resin) is not good, the one which has been surface-treated (for example, coated with silicone) with a release agent is usually used. This release agent is F even after removing the wrapping tape.
Since it remains on the surface of the RP molded product, the surface of the molded product must be polished in order to remove it and enable surface coating or the like. Generally, polishing the surface causes a problem that the strength of the pipe-shaped material is reduced.

On the other hand, in the case of a wrapping tape made of polypropylene film, it can be removed after the resin is heated and cured without treating the surface with a release agent because it has good releasability with respect to the thermosetting resin. Since the strength is lower than that of the wrapping tape, it is necessary to use a relatively thick film in order to give the wrapping tape the necessary strength. Since the wrapping tape is wound around the prepreg in a telescopic manner, the wrapping tape forms a step more or less on the surface of the FRP molded product. When a thick wrapping tape is used as described above, the step difference after molding becomes large, and the surface polishing allowance after molding also becomes large. Cause problems.

Further, in the case of a wrapping tape made of polypropylene film, the heat shrinkage rate can be set relatively high, but the heat shrinkage stress generated sharply decreases after the heat shrinkage due to stress relaxation, so that a high molding pressure should be maintained. However, it is difficult to meet the required specifications.

The object of the present invention is to pay attention to the above-mentioned problems, and it has a sufficient strength as a wrapping tape while being relatively thin, and has a good releasability to a thermosetting resin without a releasing agent. It is to provide a wrapping tape for FRP molding which has the above-mentioned characteristics and can apply a sufficient molding pressure.

Another object of the present invention is to provide a method for producing an FRP using such a wrapping tape, which does not require polishing after molding or requires a small amount of polishing.

Still another object of the present invention is to enable molding of FRP, especially CFRP, having a small surface step and high strength by using the above-mentioned wrapping tape.

[0010]

A wrapping tape for FRP molding of the present invention which meets the above-mentioned object comprises a first layer made of a heat-shrinkable film having an easy peeling property to a thermosetting resin, and a first layer thereof. Of a heat-shrinkable film having a Young's modulus higher than that of the second layer.

The FRP manufacturing method according to the present invention is
Winding a reinforcing fiber prepreg around a mandrel, winding a heat-shrinkable wrapping tape on the mandrel, when heating and molding, using the wrapping tape as described above as the wrapping tape, the wrapping tape, on the prepreg, The method comprises wrapping the first layer so that the first layer is on the prepreg side.

The wrapping tape of the present invention comprises a laminated film having a layered structure of a first layer and a second layer.
The first layer is composed of a heat-shrinkable film having an easy peeling property with respect to the thermosetting resin. Here, the term “easily peelable” refers to the property of being easily peeled from the thermosetting resin after heat curing without a release agent. Therefore, by making this surface the surface on the prepreg side, it is possible to remove the wrapping tape after heating and curing the resin, basically without using a release agent.

The second layer comprises a heat-shrinkable film having a Young's modulus (Young's modulus in the tape longitudinal direction) higher than that of the first layer. Therefore, the film layer can provide the wrapping tape with a sufficiently high strength necessary for the wrapping tape even if the entire thickness of the wrapping tape is relatively thin. This also makes it possible to apply a sufficiently high molding pressure.

Further, the heat shrinkage rate (heat shrinkage) of the first layer and the heat shrinkage rate of the second layer are made different from each other,
By stacking these films, surprisingly (as also shown in the examples below), the total thickness is the same as or larger than that of the above-mentioned laminated film, and it is more than that of either one of the film layers. Also, a high heat shrinkage stress can be obtained. Therefore, even though it is a thin wrapping tape, a sufficiently high heat shrinkage stress can be obtained, and the tightening pressure (molding pressure) by the tape at the time of molding and hardening can be increased to obtain a molded product of good quality with less voids.

In such a wrapping tape, for example, the first layer is a polyolefin film (for example, polypropylene film, polyethylene film),
The second layer is made of a polyester film (for example, polyethylene terephthalate film) and is formed by laminating these films. At the time of use, the polyolefin film layer is used as the winding surface on the prepreg side. Since the polyolefin film originally has a good releasability with respect to the thermosetting resin that serves as the matrix of the FRP, it can be easily peeled off after the resin is heated and cured without the release agent treatment. Also, the polyester film is
Since it has a higher Young's modulus and higher strength than the polyolefin film, the strength required for the wrapping tape is mainly received by this film layer.

The method for laminating the film layers is not particularly limited. For example, when a commercially available product which has already been formed into a film is used as the polyolefin film layer or the polyester film layer, a urethane adhesive or the like is used for both. It can be laminated and bonded via. Alternatively, the first layer and the second layer may be laminated by coextrusion or laminating, and then the film may be formed under a predetermined stretching condition. Further, as each film layer, both a uniaxially oriented (uniaxially stretched) film and a biaxially oriented (biaxially oriented) film can be used, but both are biaxially oriented films in terms of strength and thickness accuracy. Is preferred.

Each film layer of the wrapping tape of the present invention is not limited to the above polyester film or polyolefin film, and may be another resin film. For example, a polyaramid-based or polyphenylene sulfide-based film can be used for the film layer for imparting strength. The thickness of each film layer is also not particularly limited, but since the lapping tape as a whole is preferably relatively thin in order to reduce the step difference in the molded product, the peelable first layer has a strength of about 5 μm. It is preferable that the second layer for providing the layer has a thickness of about 10 μm.

The wrapping tape having the above-mentioned laminated film structure can be used for all FRPs, such as a sheet winding method or a filament winding method for molding a pipe-shaped FRP molded product. In particular, it is most suitable for CFRP widely used for golf club shafts and fishing rods, and a CFRP molded product having a small surface step and high strength can be obtained more reliably and at a lower cost.

The wrapping tape of the present invention and examples of molding using the same will be described below. As a wrapping tape, as shown in FIG. 1, a biaxially oriented polypropylene film 2 having a thickness of 5 μm as a first layer, and a second layer
A 10-μm-thick biaxially oriented polyethylene terephthalate film 3 as a layer was bonded via a urethane adhesive layer 4 to produce a lapping tape 1 of the present invention having a laminated film structure and a width of 15 mm.

The breaking strength, breaking elongation, Young's modulus, and 60 ° C.15 of this wrapping tape 1 at room temperature
Min, 80 ℃ ・ 15 minutes, 100 ℃ ・ 15 minutes, 120 ℃ ・ 1
Table 1 shows the result of measuring the heat shrinkage rate under the condition of 5 minutes. Also, the wrapping tape 1 has a temperature of 40 ° C to 270 ° C.
As a result of measuring the behavior of heat shrinkage stress characteristics at ℃, Fig. 2
The result as shown in was obtained (temperature rising rate: 10 ° C./min).

For comparison with the prior art, a wrapping tape of the following single-layer film having a width of 15 mm was prepared and the same characteristics as above were measured. -Biaxially oriented polyethylene terephthalate film having a thickness of 25 µm-Biaxially oriented polypropylene film having a thickness of 30 µm-Uniaxially oriented polypropylene film having a thickness of 30 µm The measurement results are shown in Table 1 and Figs.

[0022]

[Table 1]

As shown in Table 1, the wrapping tape according to the present invention has the strength and Young's modulus as high as those of biaxially oriented polyethylene terephthalate, and the elongation is as low as that of uniaxially oriented polypropylene film. Had. Further, the heat shrinkage rate showed an intermediate behavior between the biaxially oriented polypropylene film and the uniaxially oriented polypropylene film. Regarding the heat shrinkage stress, a curve similar to that of the biaxially oriented polyethylene terephthalate film and the uniaxially oriented polypropylene film was shown, but of these, the wrapping tape of the present invention having a laminated film structure had the highest heat shrinkage stress.
The shrinkage initiation temperature was almost the same as that of the biaxially oriented polyethylene terephthalate film.

Using this wrapping tape 1, a CFRP cylinder (pipe) was formed in the same manner as in the conventional method. The wrapping tape 1 was released well even after the resin was heated and cured without using a release agent. Moreover, since the wrapping tape 1 was thin, a CFRP molded product having a small surface step was obtained. Also, since no release agent is used,
The surface of the CFRP molded product could be coated as desired without polishing.

[0025]

As described above, when the FRP molding wrapping tape of the present invention is used, it has a good peeling property with respect to the thermosetting resin even though it is a thin film and without the release agent treatment. An optimum wrapping tape for use in molding, which has sufficient strength and can sustain high shrinkage stress during heat shrinkage, can be obtained. In addition, the FRP manufacturing method using this wrapping tape can provide a high-quality and high-strength FRP molded product having a small surface level difference, eliminating the need for surface polishing after molding, and having few voids. Therefore, an optimum molded product can be obtained by using it in a CFRP pipe for a golf club shaft, a fishing rod, or the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a wrapping tape according to an embodiment of the present invention.

FIG. 2 is a heat shrinkage stress characteristic diagram of the wrapping tape of FIG.

FIG. 3 is a heat shrinkage stress characteristic diagram of a wrapping tape made of a biaxially oriented polyethylene terephthalate single layer film.

FIG. 4 is a heat shrinkage stress characteristic diagram of a wrapping tape made of a biaxially oriented polypropylene single layer film.

FIG. 5 is a heat shrinkage stress characteristic diagram of a wrapping tape made of a uniaxially oriented polypropylene single layer film.

[Explanation of symbols]

1 Wrapping Tape 2 Biaxially Oriented Polypropylene Film as First Layer 3 Biaxially Oriented Polyethylene Terephthalate Film as Second Layer 4 Urethane Adhesive Layer

Claims (4)

[Claims] 1. A first layer made of a heat-shrinkable film having an easy peeling property to a thermosetting resin, and a second layer made of a heat-shrinkable film having a Young's modulus higher than that of the first layer. FRP characterized by having a layered structure with layers
Wrapping tape for molding. 2. The wrapping tape for FRP molding according to claim 1, wherein the first layer is made of a polyolefin film and the second layer is made of a polyester film. 3. The FRP according to claim 1, wherein the first layer and the second layer have different heat shrinkage rates from each other.
Wrapping tape for molding. 4. The wrapping tape according to claim 1, which is used as the wrapping tape when the prepreg of the reinforcing fiber is wound around the mandrel, and the heat-shrinkable wrapping tape is wound around the mandrel and heated to be molded. A method for producing an FRP, characterized in that the wrapping tape is wound around the prepreg such that the first layer is on the prepreg side.