JPH03234522A - Fibrous matter reinforcing sheet for reinforced plastic - Google Patents

Abstract

PURPOSE:To constitute the title sheet so that gaps are not generated between parallel fibers, by a method wherein long fibers arranged in parallel with one another to form a sheet are connected with one another by making use of a heat-fusing sheet provided with a form of nonwoven fabric or braided fabric which is extremely thin and is loose. CONSTITUTION:When a fiber sheet 1 where heat-fusing sheet 2,2 are caused to run respectively along both the front and rear is forced to pass through between a pair of hot press rollers 8, 8 the hot-melt heat-fusing sheets 2 are pressed against both the surfaces and the heat-fusing sheet 2 is cooled and solidified swiftly after passing through between the hot press rollers 8, 8. Therefore, a large number of long fibers 1a constituting the fiber sheet 1 become a state where they are connected with one another by the heat-fusing sheet 2 in a state of nonwoven fabric, a form of the sheet is set, a desired fibrous matter reinforcing sheet A is completed and wound up round a wind-up shaft 9 of a product. With this construction, it becomes that gaps are not generated among the fibers drawn up in a line. A lump of an adhesive agent stucks to a lateral fiber along the lateral fiber lies scattered concentratively locally within a fiber-reinforced plastic molded product and also lowering of strength of the whole of the product is eliminated.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides a sheet-like structure in which long fibers made of glass, carbon, aramid resin, etc. are closely arranged parallel to each other in the longitudinal direction. The present invention relates to a fibrous reinforcing sheet for reinforced plastics, which is formed into a fibrous material and whose sheet shape is fixed by adhesive means.

(Prior Art) So-called fiber-reinforced plastics, which have improved mechanical strength by embedding glass fibers, carbon fibers, or aramid resin fibers, are much lighter and have better moldability than iron. Because it has strength comparable to that of iron and cannot be cast, it has been widely adopted in various fields of industry.

The fibers for reinforcing plastics are generally used in the form of woven or nonwoven fabrics and embedded during molding of plastics.

However, when molded products require especially high strength (tensile and flexural strength) in one direction, for example, when molding blades for helicopters or generators, or cylindrical tank walls, it is necessary to The method adopted is to form a sheet by closely arranging it in parallel to the direction in which tensile stress is applied, and then impregnate this sheet-like base material with liquid resin and harden it to form it into the desired shape, thereby increasing the strength of the molded product. It is being

A reinforcing fiber sheet is used in which the plastic reinforcing fibers are pre-shaped into a sheet shape, and the parallel fibers are knitted and connected to each other by connecting horizontal fibers in the form of a raw material or a cloth. Ta.

Alternatively, as shown in FIGS. 4 and 5, the vertical fibers 51 are closely arranged in parallel to form a sheet, and the vertical fibers 5.
In order to connect each other, connecting horizontal fibers S1 were arranged at predetermined intervals, and the horizontal fibers 51 were fixed to the vertical fibers 5- using an adhesive S2. .

(Problem to be Solved by the Invention) However, when the original shape is formed as described above, a gap occurs at the seam part and fibers are missing in this part, so the reinforced plastic molding in which the fiber sheet is embedded in this state is performed. The product has a lumpy part of plastic that is not reinforced by glass fibers, so when strong stress is applied, stress cracks occur in the part where the fibers are missing, and the product breaks with much lower stress than parts reinforced with fibers. There was a fear that this would happen.

In addition, the horizontal connecting fibers are bonded to the vertical fibers,
The adhesive 52 is locally concentrated and scattered inside the molded plastic product, and the strength of this area locally decreases for the same reason as above, resulting in a decrease in the strength of the entire molded product.

Furthermore, since the above-mentioned original braiding requires special techniques and equipment for braiding, there is a problem in that the manufacturing cost increases accordingly. Such drawbacks also exist in the bonding methods described above.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a reinforced plastic material in which the long fibers are closely arranged in parallel to each other to form a sheet shape and the sheet shape is fixed, which largely eliminates the drawbacks of the conventional products. to provide fibrous reinforced sheets.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the fibrous reinforcing sheet for reinforced plastics according to the present invention comprises long fibers such as glass fibers, carbon fibers, and aramid resin fibers. 1a are closely arranged in parallel in the longitudinal direction to form a sheet, and on one or both sides of this fiber sheet 1, heat-fusible fibers are entangled with each other to form an extremely thin, coarse-grained nonwoven fabric. The structure is such that a heat-fusible sheet material 2 formed in the shape of a braided cloth is heat-sealed.

(Function) The fiber sheet 1, which is formed by closely arranging long fibers 1a in parallel in the longitudinal direction, is a heat-fusible sheet in the form of a non-woven fabric or a braided fabric, which is heat-sealed to one or both sides of the fiber sheet 1. 2, the shape of the sheet is maintained until it is impregnated with liquid resin and hardened.

The countless heat-sealed locations are distributed substantially evenly over the entire surface of the fiber sheet 1.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

First, in FIG. 2, which shows the fibrous reinforced sheet A of the present invention separated into its constituent elements, 1a is a long fiber, which is a monofilament such as glass fiber, carbon fiber, aramid resin fiber, or the like. The fiber sheet 1 is made up of a plurality of twisted wires made by bundling a plurality of monofilaments, which are closely arranged parallel to each other in the longitudinal direction to form a fiber sheet 1 having a required area.

2 is a heat-fusible sheet, in this case a heat-fusible sheet manufactured and sold by Kureha Ltd., one of Japan's leading chemical product manufacturers, under the trade name "Dynatsuku". is used.

This heat-fusible sheet 2 is produced by intertwining filaments with each other when extremely thin monofilaments of heat-fusible synthetic resin such as polystil, polyamide, polyolefin, etc. are discharged from the extrusion nozzle. It is formed into a thin non-woven fabric that can be scratched easily. Its melting point is
It varies depending on the type of resin, and is around 90 to 145°C.

A fibrous reinforced sheet A made of the above-mentioned fibrous sheet 1 and heat-fusible sheet 2 and having the cross-sectional configuration shown in FIG.
For manufacturing, for example, the manufacturing method shown in FIG. 3 is used.

That is, the long fibers 1 are individually drawn out from a large number of bobbins 3.
By passing the fiber sheet a through a guide bar 4 and a pair of guide rollers 5.5, a long fiber sheet 1 having a predetermined width is continuously formed.

When this fiber sheet 1 is passed between a pair of pressing rollers 6.degree.6, the heat-fusible sheets 2, 2 are placed along the entire surface of both the front and back surfaces of the fiber sheet 1. 1.1 is a winding shaft for supplying this heat-fusible sheet 2.2.

The fiber sheet 1, which has a heat-fusible sheet 2.2 on both sides, is passed between a pair of heat-pressing rollers 1, 1, and when it is passed between a pair of heat-pressing rollers 1, 1, the heat-fusible sheet 2 is melted on both sides. After being pressed against the surface and passing through a hot pressure roller 1.8, this heat-fusible sheet 2 is rapidly cooled and solidified.

Therefore, a large number of long fibers 1a constituting the fiber sheet 1 are connected to each other by the nonwoven heat-fusible sheet 2, and the sheet shape is fixed, resulting in the desired fiber reinforced sheet A. is completed and wound onto the product's winding shaft.

The fibrous reinforced sheet A having such a structure has no directionality because the heat-fusible sheet 2, which is heat-sealed with a substantially uniform distribution over its entire surface, has no directionality. Unlike those knitted in the original state, there is no inconvenience such as gaps between the fibers arranged in parallel.

In addition, a drawback of the conventional structure in which the horizontal fibers are bonded to the vertical fibers arranged in parallel is that the lumps of adhesive adhered along the horizontal fibers are locally concentrated inside the fiber-reinforced plastic molded product. There is no longer a need for particles to be scattered and reduce the strength of the entire product.

In the above configuration, the method of fusing the thermally bonded sheet 2 to the fiber sheet 1 is, for example, by using a simple pressure roller instead of the heat pressure roller 8 and using a heater provided in front of the pressure roller to bond the fiber sheet 1 to the fiber sheet 1. It may be selected as appropriate, such as heating the surface of the heat-fusible sheet 2 to a temperature higher than the melting point.

Further, the heat-fusible sheet 2 is not in the form of a non-woven fabric like the above-mentioned "Dynac", but may be in the form of a coarsely woven fabric in which the orientation direction of the fibers is aligned, for example, vertically and horizontally.

Further, the heat-fusible sheet 2 may be applied not to the entire surface of the fiber sheet 1 but to a portion thereof, for example, in a striped manner.

The material of the heat-fusible sheet 2 is not limited to those mentioned above, and other heat-fusible materials may be selected as appropriate. Heat-fusible sheet 2 made by mixing multiple different types of fibers
You may also use

Furthermore, if the material for the heat-fusible sheet 2 is a material that can be chemically dissolved in the solvent in the resin stock solution for molding reinforced plastics, such as the styrene monomer in unsaturated polyester resin, it will be possible to bond with the reinforcing base material and harden. A reinforced plastic molded product made only of resin can be obtained.

Therefore, the strength of the product cannot be reduced due to the adhesive being locally mixed into the molded product as a foreign substance, unlike in the conventional method.

[Effects of the Invention] As is clear from the above explanation, the fibrous reinforcing sheet for reinforced plastics according to the present invention has a thin and thin structure in which the long fibers arranged parallel to each other are scratched to form a sheet. Since the heat-fusible sheets in the form of coarse non-woven fabric or braided fabric are used to connect them by heat welding, there is a problem in that gaps are created between the parallel wires I11, unlike conventional braided wires. do not have.

In addition, unlike conventional sheets that have a structure in which horizontal fibers for connection are bonded to parallel vertical fibers, the heat-sealing sheet that acts as an adhesive between parallel fibers is different from conventional sheets in that it does not remove unnecessary resin lumps. The structure in the plane direction is kept almost uniform.

Therefore, unlike conventional products, reinforced plastic molded products made using this fibrous reinforced sheet have adhesives that are locally concentrated and scattered (see Figure 5). There is no need to reduce the strength of the entire product.

Furthermore, since the fibrous reinforced sheet can be produced by simply heating and pressing a heat-adhesive sheet onto the surface of the fibrous sheet, the manufacturing cost is much lower than that of the conventional sheet, and it is a homogeneous product. It has various excellent effects such as easy to obtain.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
FIG. 1 is a partially enlarged vertical sectional view, FIG. 2 is a partially enlarged perspective view showing the fiber sheet and the heat-fusible sheet separated, and FIG. 3 is a sketch showing an example of the manufacturing process. FIGS. 4 and 5 are a perspective view and a vertical sectional view showing a conventional example. Number: Fibrous reinforced sheet Fiber sheet Heat-fusible sheet Guide bar press roller Heat pressure roller Vertical fiber Adhesive Long fiber Bobbin Guide roller Winding shaft Winding shaft Sl Horizontal fiber

Claims (1)

[Claims] (1) Long fibers 1a such as glass fibers, carbon fibers, aramid resin fibers, etc. are closely arranged in parallel in the longitudinal direction to form a sheet, and one or both sides of this fiber sheet 1 are coated with heat-meltable A fibrous reinforcing sheet for reinforced plastics, which is made by heat-sealing a heat-fusible sheet material 2 which is formed by intertwining fibers having the following properties with each other to form an extremely thin coarse non-woven fabric or braided fabric.