JPH0349349Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is a multi-layered FRP having a layer (FRP layer) in which glass filaments are impregnated with a thermosetting resin and wrapped around it.
The present invention relates to pipes, and specifically relates to a multilayer FRP pipe in which FRP layers are formed on at least the inner and outer layers, and a layer with extremely good watertightness is provided as an intermediate layer.

[Prior Art] As is well known, reinforced plastic pipes with an FRP layer (hereinafter referred to as FRP pipes) are lightweight and have excellent corrosion resistance and pressure resistance, so they are attracting attention as an alternative to concrete pipes, metal pipes, and ceramic pipes. has been done. Various methods are known for manufacturing FRP pipes, and the following are the main ones.

(1) Filament winding method (FW method) in which long glass fibers impregnated with resin are continuously wound around a core metal.

(2) A centrifugal casting method in which a combination of glass fiber, resin, aggregate, etc. is used and laminated and molded using centrifugal force.

[Problems that the invention aims to solve] However, this type of FRP pipe is used for relatively large diameter pipes and may be subjected to large internal water pressure, so it is necessary to improve not only strength but also watertightness.

FRP pipes made using the FW method have high tensile strength in the direction in which the long glass fibers extend, but in order to be used as high-pressure pipes, it is necessary to have high watertightness.
If you try to secure it with layers, you will need to wind more layers of fiber than necessary, or you will need to wind a small amount of fiber densely over a long period of time, such as in helical winding. However, when a large amount of winding or particularly dense winding is performed, the voids between the filaments are reduced, the amount of impregnated resin is reduced, and watertightness may be lacking.

On the other hand, in the case of centrifugal casting, watertightness is generally improved because a large amount of resin is contained, but the amount of resin is higher than the minimum amount required to maintain strength!
It requires a lot of resin and is uneconomical.

The present invention was developed in view of the above-mentioned current situation, and aims to compensate for the drawbacks of the FRP layer formed by the methods exemplified above, and to realize a multilayered FRP pipe with improved watertightness.

[Means for solving the problem] The present invention is a multilayer type having FRP layers as inner and outer layers.
The gist of this is that in an FRP pipe, an intermediate layer is formed by impregnating short fibers with a soft resin.

[Operation] The operation of the present invention will be explained according to the drawings of the embodiment.
FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and the multilayer FRP pipe 1 of the present invention has FRP layers formed as an inner layer 2 and an outer layer 3, and an intermediate layer 5 between them. is formed. The intermediate layer 5 is made by impregnating irregular short fibers (for example, short glass fibers) with a soft resin. Therefore, the soft resin reliably penetrates between the fibers to form an extremely tight intermediate layer 5. By adopting the above configuration, it is possible to prevent the occurrence of cracks, pinholes, etc., and to realize an FRP pipe 1 with extremely good watertightness.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

[Embodiment] FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. In the multilayer FRP pipe (hereinafter simply referred to as FRP pipe) 1 of the present invention, an inner layer 2 and an outer layer 3 (each an FRP layer) are formed according to a conventional method. middle layer 5
For example, short glass fibers are impregnated with a soft resin, and therefore the soft resin reliably penetrates between the fibers to form an extremely tight intermediate layer. However, by adopting the above configuration, it is possible to prevent the occurrence of cracks, pinholes, etc., and to achieve extremely good watertightness.
FRP pipe 1 can be realized. Furthermore, FRP pipe 1 of the present invention
Since the inner and outer layers 2 and 3 are the same FRP layers as before,
The original characteristics of FRP pipes, such as chemical resistance and flexibility, are not impaired.

The short glass fibers used in the intermediate layer 5 are so-called chipped strands, and when the short fibers are impregnated with a soft resin to form the intermediate layer 5, the short fibers and the soft resin are compatible with each other. is extremely good, and there are no air bubbles that can cause pinholes. Furthermore, even if a crack occurs in the intermediate layer 5, since the intermediate layer 5 is a layer containing short fibers in unspecified directions, the propagation of the crack will be dispersed, and the crack will spread further. Things like this can be prevented.

According to the above configuration, an FRP pipe with extremely good watertightness can be provided using the minimum amount of glass fibers in accordance with the design strength. By the way, when comparing the water pressure resistance of a pipe of the present invention and a conventional pipe made with the same amount of glass fiber, the water pressure value of the product of the present invention was improved by 11.0 kg/cm ² (14.8% higher than the conventional product). ).

Although the embodiment shown in FIG. 1 has a three-layer structure of the inner layer 2, outer layer 3, and intermediate layer 5, it is not necessary to be limited to the structure shown in FIG. 1, and for example, as shown in FIG. 2 (other embodiment drawings). A resin mortar layer 7 may be disposed between the outer layer 3 and the intermediate layer 5 as shown in FIG. Layer 6 and resin mortar layer 7
may be arranged in this order.

[Effect of the invention] By adopting the above configuration, it is possible to provide a multilayered FRP pipe with improved watertightness without impairing the original characteristics of the FRP pipe (for example, chemical resistance, flexibility, etc.) was completed.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of one embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of another embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view of yet another embodiment of the present invention. 1... Multilayer FRP pipe, 2... Inner layer, 3... Outer layer, 5... Intermediate layer, 7... Resin mortar layer.

Claims (1)

[Scope of utility model registration request] A multilayer FRP pipe having FRP layers as inner and outer layers, characterized in that an intermediate layer is formed by impregnating short fibers with a soft resin.