JPH0324332B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fiber-reinforced resin plate, and more specifically, to a fiber-reinforced resin plate that is convex only on one side, such as a contact plate for an X-ray imaging device or a parabolic antenna. This invention relates to a fiber-reinforced resin board whose thickness decreases from the center toward the edges.

The fiber reinforced resin (hereinafter referred to as FRP) board is
They are not only made in the form of a flat plate, but also in a variety of shapes depending on the purpose. for example,
In continuous X-ray imaging equipment used for human diagnosis, an FRP contact plate is used to press the film, which is sent intermittently at a high speed of, say, 6 frames per second, against an intensifying screen at the imaging position. However, when the contact plate is flat, it traps air between the film and the intensifying screen when it is pressed.
Since it is not possible to achieve good adhesion between the two, the first
As shown in the figure (schematic vertical cross-sectional view), it is slightly convex only on the pressing surface side, and the thickness gradually decreases from the center of the convex surface toward the edge.
Such FRP adhesive plates are formed by stacking reinforcing fibers, such as fiber prepreg, in order from large to small and heating and pressing, but the shape seen from the center of the thickness is not symmetrical like a flat plate. Because there is no such thing, it will warp to the convex side after molding. In an attempt to prevent the occurrence of this warping, attempts have been made to increase the amount of resin in the portion close to the other non-convex surface compared to the portion close to the convex surface. In other words, this uses the shrinkage force of the resin to apply a force that tries to pull it back against the force that tends to warp toward the convex surface after molding, and to balance the two forces and prevent the occurrence of warp. It is something to do. However, this FRP board also undergoes stress relaxation after a long period of time after being molded, and begins to warp to the convex side. In addition, in order to mold the adhesive plate as described above, many types of prepreg with different resin contents are prepared,
It is necessary to stack the prepregs in order from highest to lowest resin content, but it is not only extremely troublesome to prepare multiple types of prepregs with slightly different resin contents, but it is also necessary to stack them in order so as not to make a mistake. It is extremely complicated to superimpose the images in sequence.

The purpose of the present invention is to solve the above-mentioned drawbacks of conventional FRP boards, to be able to prevent warping after molding, especially its change over time, and to be extremely easy to mold.
An object of the present invention is to provide an FRP board suitable for use as a contact plate for radiographic equipment or as a parabolic antenna.

To achieve the above object, the present invention is a laminate formed by stacking a plurality of sheets of continuous reinforcing fibers, and a board made of a resin that includes and integrates this laminate, the board comprising: It is convex only on one side, and the thickness decreases from the center of the convex side toward the edge, and there are reinforcing fibers in the resin between at least one laminated sheet between the center of thickness and the other non-convex side. It is characterized by a fiber-reinforced resin board in which milled fibers or short fibers are interposed.

To explain one embodiment of the FRP board of the present invention, in FIG. 2 (schematic longitudinal cross-sectional view), the FRP board consists of a large number of sheets 2 made of continuous reinforcing fibers stacked one on top of the other in order from large to small. It consists of a laminated body and a resin (not shown) that includes and integrates this laminated body. Furthermore, another sheet 3 is provided in the outer layer portion so as to cover the above-mentioned laminate.
are superimposed, but this is not necessary. When viewed as a whole, the FRP board 1 is convex only on one side (upper side in FIG. 2), and the thickness decreases from the center of the convex surface toward the edge, drawing a gentle normal distribution curve. Furthermore, milled fibers (hereinafter referred to as MF) or short fibers 4, which are reinforcing fibers, are interposed between the two laminated sheets between the thickness center and the other non-convex surface. In addition,
When the FRP board 1 is used as the contact plate, the other surface may be slightly convex toward the convex surface. When used as a parabolic antenna, the other surface forms a paraboloid of revolution.

The reinforcing fibers are high-strength, high-modulus fibers such as carbon fibers, glass fibers, organic high-modulus fibers (eg, polyaramid fibers, etc.). When constructing the above-mentioned contact plate, carbon fiber is used because it allows X-rays to easily pass through it, reducing the exposure dose to the human body, and because it has the highest strength and elasticity, it has the greatest reinforcing effect. is most preferred. Furthermore, in the case of a parabolic antenna, carbon fiber is used because the radio wave reflecting surface needs to be conductive. However, the reinforcing fibers mentioned above are of the same type.
Different types of FRP boards may be used. For example, in the case of a parabolic antenna,
When viewed from the center of thickness, carbon fibers can be used on the other surface side forming the paraboloid of revolution, and inexpensive glass fibers or organic high-elastic fibers can be used on the convex surface side.

The sheet is made of fibers or reinforcing fibers arranged parallel to each other in one direction in a sheet shape. In other words, the sheet is composed of continuous reinforcing fibers. When the sheets are the above-mentioned unidirectionally aligned bodies, it is preferable that the sheets are laminated so that their fiber axes intersect with each other, for example, orthogonally. On the other hand, MF is extremely short with a length of 0.01 to 0.4 mm. 10-40 in aspect ratio
That's about it. Further, short fibers have a length of 1 to 50 mm and are usually used in the form of paper or matte.

These MF and short fibers form a resin-rich layer between the thickness center of the FRP board and the other surface, and prevent stress relaxation from occurring in that layer.
To that end, they are preferably rigid, carbon fiber being most convenient. And M.F.
When using, the amount is preferably 0.05 to 10% by weight of the entire FRP board. In other words, if it is less than 0.05% by weight, the effect of creating a resin-rich layer is small, and if it exceeds 10% by weight, voids tend to remain in the FRP. When short fibers are used in the form of paper or matte, they have a greater effect of creating a resin-rich layer than MF, so they have a basis weight of 10 to 50 g/ ^m2 , preferably 10 to 30 g/m2.
It is best to use a material of ^m2 , and it is also preferable to use a material that is as thin as possible so as not to increase the thickness of the FRP board.

The extent to which the MF and short fibers are interposed from the other surface of the FRP board is determined depending on the degree of convexity, etc. At most, it is sufficient to extend from the other surface to the center of the thickness of the plate. These MF and short fibers are interposed between all the laminated sheets from the other side of the FRP board to a certain part, and when they are interposed only between specific laminated sheets, for example, between the outermost laminated sheets. There is. the same amount
If MF or short fibers are used, the former is preferable. Further, since MF has a great effect of preventing mutual movement of sheets, and short fiber paper and mat have a great effect of creating a resin-rich layer, it is also preferable to use these in combination. In that case, short fiber paper or mat is placed between the laminated sheets in the portion close to the other side.

As explained above, the FRP board of the present invention has reinforcing fibers such as MF or short fibers interposed in the resin between at least one laminated sheet between the thickness center and the other non-convex surface. MF or short fibers can prevent deformation of the resin between laminated sheets, and can prevent warping after molding, especially its change over time. In addition, unlike conventional FRP boards, there is no need to prepare many types of prepregs with slightly different resin contents during molding, and such prepregs can be layered in order from the highest resin content to the lowest resin content. Since this is not necessary, the FRP board of the present invention is extremely easy to mold.

Example Carbon fiber plain weave manufactured by Toray Industries, Inc. #6343 (Weight 200
A woven prepreg was prepared by impregnating epoxy resin # ²⁵⁰⁰ for prepreg manufactured by Toray Industries, Inc. to a content of 42% by weight. From this prepreg, the number of layers is 17 as shown in Figure 2.
For molding FRP boards, for 1 to 9 layers and 16,
One cut to 350 x 350mm for 17 layers, and 10~
0.2 from the top of the FRP board after molding for 15 layers
We prepared pieces cut into shapes similar to those obtained when sliced into rounds with a thickness of mm.

Next, the above prepregs were stacked one on top of the other in order from 1 layer to 17 layers to obtain a laminate. At this time, carbon fiber MF (type
VM0045) was interposed in a substantially uniform distribution at 2 g each.

Next, the above laminate was placed in a mold and heated at 130°C for 8
The FMP of the present invention is heated and pressurized for 1 hour under the conditions of Kg/ ^cm2 , and has a convexity on only one side, and the thickness gradually decreases from the center of the convexity toward the edge.
Got the board. This FRP board, both length and width
350mm, and the maximum height was 3.9mm.

When the above FRP board was placed on a surface plate, all four corners and sides were in contact with the surface of the surface plate, and no lifting was observed. Furthermore, the gap between the surface of the surface plate and the other surface of the FRP plate was 0.37 mm. This gap is 1
Even after leaving it for a month, it remained almost unchanged at 0.33mm.

Comparative Example FRP was produced in exactly the same manner as in the above example except that MF was not used. When the obtained FRP board was placed on a surface plate, there was a maximum gap of 0.4 mm between the surface and the four corners and sides, and this gap doubled to 0.8 mm after being left for one month. Summer.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional view showing an FRP contact plate for an X-ray imaging device, and FIG. 2 is a schematic vertical cross-sectional view showing an embodiment of the FRP plate of the present invention. 1: FRP board, 2, 3: Sheet made of continuous reinforcing fibers, 4: Milled fibers or short fibers of reinforcing fibers.

Claims (1)

[Claims] 1 A laminate made of a plurality of sheets of continuous reinforcing fibers stacked together, and a board made of a resin that encompasses and integrates this laminate, and the board is convex only on one side, and the convex surface is convex. The thickness decreases from the center toward the edge, and reinforcing fibers such as milled fibers or short fibers are interposed in the resin between at least one laminated sheet between the center of thickness and the other non-convex surface. A fiber-reinforced resin board featuring: