JPH09272155A - Laminated plate and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: A shrinkage factor of a laminated plate with respect to a temperature change, particularly a shrinkage factor at an extremely low temperature is reduced, and mechanical strength is improved, and it is suitable as a structural material for superconducting equipment. To do. SOLUTION: In a laminated plate formed by laminating a plurality of fiber base materials impregnated with a thermosetting resin, the thermosetting resin has a spherical or subspherical shape such as silica having an average particle diameter of 0.3 to 5 μm. By adding an inorganic filler or a short fiber inorganic filler such as short fiber or needle glass, the shrinkage in the layer direction is low even with a wide temperature difference, and the mechanical strength is improved. I shall.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate used as an insulating structure, and more particularly to a laminate suitable as a constituent material for superconducting equipment used at extremely low temperatures and a method for producing the same.

[0002]

2. Description of the Related Art Laminated plates obtained by impregnating a reinforcing fiber or a woven cloth (cloth) of reinforcing fibers with a thermosetting resin, laminating a plurality of the laminated sheets, and applying pressure and heat are used. It is a composite and is generally called a laminated plate or FRP and is used in various fields. Among them, glass-reinforced fiber epoxy resin laminated plates are most widely used in electrical equipment.

This epoxy resin laminated plate is excellent in electrical insulating properties and mechanical properties, has well-balanced properties that can be widely applied in heat resistance, and is economical. However, since the layers are laminated, expansion and contraction in the through layer direction are large, and mechanical strength in the direction of peeling the layers is desired to be higher.

Therefore, studies have been conducted to reduce the amount of resin from the usual 30-40 wt% to the limit in order to suppress expansion and contraction in the direction of the through layer to a small extent. On the other hand, there is also an attempt to reduce the resin amount by filling a space between cloths by compounding a filler with the impregnated resin. For example, CEC / ICMC i
n Albuque Arb-8 “GLASSFIBER REINFORCED PLASTICSFO
R CRYOGENIC USE IMPROVEMENT OF THEMAL CONTRACTION
AND ELASTICMODULUSIN THICKNESS DIRECTION ”and 1
According to "Development of High-performance Laminated Plates for Cryogenic Temperature," 1994 Annual Electric Breakthrough Exhibition, the amount of resin must be 30 wt% or less in order to achieve a shrinkage of about 0.3% from room temperature to liquid nitrogen temperature. However, it is desirable to extend this to the actual helium temperature to further reduce shrinkage.

However, looking at the result of compounding the filler in the former document among the above-mentioned documents, although the resin matrix has an effect on both the shrinkage ratio and the compressive strength,
When this is molded as a laminated plate together with the reinforcing fiber, it has almost no effect on the shrinkage ratio, and the bending strength is significantly reduced.

As described above, it has not been possible to achieve further improvement of the properties of the laminated plate to have a low shrinkage and a high strength. Nevertheless, in recent years, the products of superconducting devices have expanded, and the demand for such improved characteristics has further increased.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and reduces the shrinkage rate in the direction of the through layer when the temperature is changed from room temperature to very low temperature in a laminated board used as an insulating structure. The present invention also aims to improve mechanical strength, and particularly to provide a laminated plate applicable to superconducting equipment used at extremely low temperatures.

[0008]

Means for Solving the Problems The present invention relates to a laminated plate in which a plurality of fiber base materials impregnated with a thermosetting resin are laminated, and a spherical or subspherical inorganic filler is added to the thermosetting resin. It is characterized by Further, in a laminated plate formed by laminating a plurality of fiber base materials impregnated with a thermosetting resin, a spherical or subspherical inorganic filler and a short fiber inorganic filler are added to the thermosetting resin. .

In the above, the spherical or sub-spherical inorganic filler preferably has an average particle size in the range of 0.3 to 5 μm, and particularly preferably contains silica as a main component. These are obtained by melting and then granulating. Also,
The short fiber inorganic filler is preferably short fiber or crystal needle-shaped (whisker) glass. Further, the glass short fibers have a diameter of 2 to 20 μm, a length of 3 to 300 μm, and an average length of 1
00 μm or less is preferable.

When both the spherical or sub-spherical inorganic filler and the short fiber inorganic filler are added, the ratio of both is 20 to 80% by weight for the former and 80 to 20% by weight for the latter. Alternatively, the average diameter of the sub-spherical inorganic filler is preferably 1/2 or less of the average diameter of the short fiber inorganic filler.

The present invention also relates to a method for producing the above laminated plate, in which a fibrous base material is impregnated with a spherical or sub-spherical inorganic filler or a thermosetting resin containing this and a short fiber inorganic filler, which is then impregnated. It is characterized in that it is dried to form a prepreg sheet, and a plurality of prepreg sheets are stacked and cured by heating under pressure. Here, after the fiber base material is impregnated with the thermosetting resin, it is advisable to adjust the applied surface and the applied amount on both sides using a bar coater. This may damage the fiber base material due to the pressure applied when molding the laminate, especially when using short fiber inorganic fillers,
This is because it is necessary to prevent this. When the bar coater is used, the short fiber inorganic filler on the convex portion of the fiber base material can be straightened in the weave of the cloth or in the direction along the fiber without damaging the fiber base material. A squeegee may be used instead of the bar coater.

[0012] A laminated plate which is generally used at present is one in which a resin is applied to a reinforcing fiber or a woven fabric (cloth) of the reinforcing fiber and laminated, and since the weave of the cloth is formed as a resin, Expansion and contraction are very large compared to the fiber direction, which is a problem. Therefore, it is possible to reduce the expansion and contraction by adding a filler to the resin, but the filler that has been used in the past is a crushed product, and depending on the particle shape and particle size, when forming a laminated plate The base fibers are damaged by the pressure.

In the present invention, since the spherical or sub-spherical inorganic filler is used, there is little risk of conforming to the cross stitch and damaging the base fiber. Further, the particle diameter is smaller than the fiber diameter and is 0.3 to 5 μm, so that it is well impregnated between the fibers and the weave of the cloth. If it is smaller than 0.3 μm, the viscosity of the impregnated resin becomes high and sufficient impregnation cannot be performed, which is not preferable.

In the present invention, when the short fiber inorganic filler is blended with the spherical or subspherical inorganic filler,
The adhesive force between layers when laminated can be increased. In that case, the diameter of the short fiber inorganic filler is 2 to 20.
μm, a length of 3 to 300 μm and an average length of 100 μm or less makes it easy to impregnate the cloth texture,
There is little concern that the base fibers will be damaged by the pressure applied when forming the laminate. The compounding ratio with the spherical or sub-spherical inorganic filler is 20 to 80% by weight for the former and 80 to 80% for the latter.
When it is 20% by weight, it has the effect of lowering the viscosity of the impregnating resin, and the impregnating property becomes excellent. In this case, the spherical or sub-spherical inorganic filler needs to have an average diameter of 1/2 or less of the average diameter of the short fiber inorganic filler, and if it is more than this, there is almost no effect of decreasing the viscosity.

Generally, when a laminated plate is used at an extremely low temperature, it is cooled from room temperature by about 300 K, and the shrinkage factor at that time affects the reliability of the device as a thermal strain. The shrinkage rate is 0.4-0.5 in the conventional laminate.
%, The difference is large compared to 0.3% of stainless steel materials that are often used. In superconducting equipment, the electromagnetic force is strong,
Since the size is large and the dimensional accuracy is strict, the influence of the shrinkage factor on the reliability is further increased. Therefore, at least a contraction rate of stainless steel is required. The laminated board of the present invention can meet such requirements.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) Bisphenol A type epoxy resin 100
Part, 3 parts of dicyandiamide, 0.1 part of 2-ethyl-4-methylimidazole and 60 parts of acetone were added and stirred to melt, and then 100 parts of spherical silica (average particle size 1.5 μm) was added as an inorganic filler. An epoxy resin varnish was prepared. A glass cloth having a thickness of 190 μm was coated and impregnated with this varnish and dried at a temperature of 130 ° C. to prepare a prepreg.

Twenty-four of these are stacked and heat-pressed to 170
It was integrally molded at 40 ° C. and 40 kg / cm 2 for 60 minutes to prepare a laminated plate having a thickness of about 3 mm. As a comparative example, as shown in Table 1, a laminate containing no filler and a laminate containing crushed silica or crushed alumina were prepared in the same manner.

Example 2 The same as Example 1 except that 50 parts of spherical silica (average particle size 1.5 μm) and 50 parts of glass short fibers (diameter 12 μm, average length 70 μm) were used as the inorganic filler. A laminated board was prepared by the method.

Example 3 In Example 2, when the epoxy resin varnish was applied to the glass cloth, the diameter was 5 mm.
A stainless steel rod was used as a bar coater to adjust both sides to prepare a prepreg. Other than that, the laminated plate was prepared as described above.

The laminates of Examples 1 to 3 and Comparative Example were placed at room temperature to 4.2K and room temperature to liquid nitrogen temperature, and the shrinkage rate (%) was examined. Moreover, the layer-direction compressive strength and bending strength (MPa) were examined. The results are as follows.

[0021]

[Table 1]

[0022]

As described above, the laminated plate of the present invention has a low shrinkage in the layer direction even when the temperature changes to an extremely low temperature, and the mechanical strength does not decrease. Therefore, it is useful as an insulating and structural material for devices used at extremely low temperatures, especially superconducting devices.

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Claims (8)

[Claims] 1. A laminated plate obtained by laminating a plurality of fibrous base materials impregnated with a thermosetting resin, wherein a spherical or subspherical inorganic filler is added to the thermosetting resin. 2. A laminate comprising a plurality of fiber base materials impregnated with a thermosetting resin, wherein a spherical or subspherical inorganic filler and a short fiber inorganic filler are added to the thermosetting resin. Characteristic laminated board. 3. The laminated plate according to claim 1 or 2, wherein the spherical or subspherical inorganic filler has an average particle size of 0.3 to 5 μm. 4. The laminated plate according to claim 1, wherein the spherical or subspherical inorganic filler contains silica as a main component. 5. The laminate according to claim 2, wherein the short fiber inorganic filler is short fiber glass or crystal needle glass. 6. Short fiber-like or crystal needle-like glass having a diameter of 2 to 20 μm, a length of 3 to 300 μm, and an average length of 100.
The laminated plate according to claim 5, having a thickness of not more than μm. 7. A prepreg green sheet obtained by impregnating a fibrous base material with a spherical or sub-spherical inorganic filler or a thermosetting resin to which the inorganic filler is added and a short fiber inorganic filler, and drying the prepreg sheet. A method for manufacturing a laminated board, comprising stacking a plurality of the sheets and curing them by heating under pressure. 8. A spherical or sub-spherical inorganic filler or a thermosetting resin containing this and a short fiber inorganic filler is impregnated into a fiber base material, and both surfaces are adjusted with a bar coater or a squeegee. Item 7. A method for manufacturing a laminated board according to item 7.