JPS608056A - Composite material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new type of composite material that has electromagnetic shielding properties and is used to make lightweight and strong molded products.

BACKGROUND OF THE INVENTION With the recent development of electronic equipment, and in particular the improvement of peripheral technologies such as various printed wiring boards and integrated circuits that form the basis of electronic equipment, there has been a remarkable development in the relationship between demand and supply of consumer electronic equipment.

As the number of electronic devices owned by households or individuals increases significantly, it is naturally expected that the number of various troubles that occur will increase.

The biggest cause of this is the influence of electromagnetic waves on these electronic devices.For example, in computers, it can lead to misleading information and errors in calculations, and in display devices such as VTRs, it can cause problems in terms of images such as colors. It can be considered.

One of the most familiar examples is that electronic devices installed in cars, for example, continue to receive electromagnetic waves from spark plugs ever since the starter is turned on to put the car into operation, and this often causes noise. Are known.

As described above, there are countless sources of electromagnetic waves in the surrounding area, and therefore, measures are taken to prevent these electronic devices from being affected as much as possible.

Specifically, for example, shielding a specific part of a normal TV receiver or shielding the entire housing of a VTR device; as long as the shield inside the device performs its function, there is no need to consider the decorative effect. No, but
In the case of the housing material, a material made of a thin steel plate with synthetic resin layers on both sides is used.

By the way, with the material of the above-mentioned structure, electromagnetic waves generated externally can be reflected and quickly cut off, but not only does it have the disadvantage that electromagnetic waves generated within the device are also reflected into the device, but also the material forming the center layer No matter how well the surface of a metal plate (or foil) is treated, it is inevitable that peeling will occur due to differences in the coefficient of expansion of the materials, and peeling may occur due to the processing of composite plates. This has the disadvantage that it makes IO easier.

As a means of improving this, it may be possible to use a wire mesh in place of the metal plate or foil, but the electromagnetic wave shielding performance will fluctuate due to uneven and unstable contact conditions at the contact points of the wire that forms the mesh. Not only is there a risk of causing damage, but also it is impossible to form a smooth surface unless the resin layer has a certain thickness or more due to the protrusions at the intersections of the wires when forming the net.

It is also conceivable to knead a conductive filler separately from such a metal plate (or foil) or wire mesh. In this case, if the crosstalk conditions are carefully considered, the filler will be dispersed uniformly in the resin and non-uniformity will disappear, but if fibrous filler is mixed in the resin, there will naturally be a limit to the amount of filler added. Therefore, it is difficult to obtain a sufficiently satisfactory electromagnetic shielding effect.

Furthermore, methods such as applying conductive paint or metal spraying may be considered, but in these cases, the object to be treated must be already shaped. Therefore, it is not a complicated process that requires a separate treatment process (and a preparation process is also added), but there is a risk of peeling because it is simply painted or thermally sprayed. This is quite undesirable.

The present invention eliminates the drawbacks of each of the above-mentioned methods,
Furthermore, we have arrived at this as a result of various studies to develop an electromagnetic wave shielding material that is lightweight as a basic material and has excellent strength as an alternative to conventional reinforced materials such as glass fiber.
One or more types of thermosetting resin forming precursors such as unsaturated linear polyester, resol-type phenol-formalin condensate, or thermosetting epoxy resin, and at least two sheets of steel foil therein. The present invention relates to a composite material characterized by being electrically insulated from each other.

Unsaturated linear polyesters include maleic acid, fumaric acid,
It refers to the condensation of unsaturated dibasic acids such as phthalic acid or their acid anhydrides and adipic acid with dihydric alcohols such as ethylene glycol and propylene glycol. Using reaction products of hydric phenols.

Note that the thermosetting resin forming precursor as used in the present invention refers to the aforementioned unsaturated linear polyester, resol type phenol,
The lath used in the present invention refers to a formalin condensate and thermosetting epoxy resin that still retains sufficient plasticity without three-dimensional reticulation. ) is made by making slits and then pulling this metal plate (foil) to form a mesh.

The steel lath obtained by this method may be used as is, but in order to prevent corrosion of the lath due to moisture or ventilation that migrates through the resin over a long period of time, or the peeling phenomenon caused by this corrosion, zinc It is desirable that the product be subjected to treatments such as plating, galvanizing and chromate treatment, and anti-rust painting.

At least two laths prepared in the above manner are
They must be electrically insulated from each other, and therefore, if the laths are not coated with an insulating coating, it is necessary to interpose some kind of spacer between them.

As the spacer, for example, a synthetic resin net, short glass fiber products, braided products, etc. can be used.

In addition, when performing insulation coating, the insulation coating material is mainly selected from synthetic resin paints such as phenol resin, alkyd resin, melamine resin, polyester resin, and epoxy resin, among which epoxy resin is used. It is easier to obtain stable results when

Although the present invention uses at least two laths of steel foil, laths are generally shipped in the form of rolls, so the composite of the present invention can be produced in a continuous manner using these rolls. Although it is possible, it is not particularly limited to a continuous method, and it is also possible to manufacture by a batch method.

In any case, it is not necessary that the meshes of the two laths used be the same; on the contrary, if laths with different meshes are used, favorable results can be obtained for the shielding or absorption effect over a wide electromagnetic wave band. Cheap.

In addition, in the case of a batch method, it is possible to stack a plurality of adjacent laths so that the mesh directions of the laths are shifted by 90 degrees from each other, which further helps to improve the strength of the final product.

When we tested the electromagnetic wave shielding performance and electromagnetic wave absorption performance when the composite material obtained with the above configuration was cured and made into a plate material, the relationship between the mesh opening of the steel foil lath used was shown in Figure 1. It was found that in order to satisfy both the electromagnetic wave shielding performance (shielding group S%) and the absorption performance (absorption rate ab%), the angle should be approximately 2/2° to 2/2.

The molded and hardened composite material obtained by the present invention can be used as an exterior strength member.For example, it can be used as a material for absorbing and shielding electromagnetic waves in automobiles equipped with electronic devices, which have recently become commonplace. It can be used in place of FRP.

The present invention will be explained below with reference to Examples.

EXAMPLE A composite material was produced using a composite material production line as schematically shown in FIG. 2.

In the figure, 1.2 is a lath material supply line, 6.4 is a precursor solution supply line for forming a thermosetting resin, and 5 and 6 are protective polyethylene sheets.

Precursor solution composition Equivalent compound of diethylene glycol, fumarate and styrene 100 Parts by weight Di-t-butyl peroxide 2 Calcium carbonate 70 Zinc stearate 1 Magnesium oxide 2 The steel foil lath is a 70 μm thick sheet coated with epoxy resin paint. I used two pieces. The opening diameter and porosity of the lath mesh are 2"'x3", 50% and 6IllIx, respectively.
10■, 80% was used.

Also, as a spacer between two laths, an average of 25 m
A long piece of deer glass fiber was randomly placed over it to the extent that the lath underneath was no longer visible.

The precursor solution was applied uniformly using a doctor blade, and the thickness of the composite was adjusted to 2 mm.

When the thus obtained composite material was kept at 45° C. for one day, the precursor solution underwent prepolymerization and thickened, and the phenomenon of dripping of the solution from around the material to be bonded disappeared.

The protective polyethylene sheet on the surface was removed, and the product was placed in a mold for molding an automobile bonnet and pressed under conditions of 150°C, 100°C (unbalanced), and 2 minutes. Regarding the obtained cured product,
When the electromagnetic wave shielding effect in the range of 10 to 0.1 GHz was measured, the results shown in the following table were obtained.

For comparison, a piece molded in the same manner using a piece of wire mesh with nominal hi was measured under the same conditions, and the result was 10.
The value at GHz is a common indication, and it was not possible to maintain this value in other frequency bands.

Reflectance Absorption rate Transmittance% % Thin lath 47 52.9 0.1 Wire mesh 74 8 18 In addition, in FIG. 2, depending on the lath or spacer used, the precursor supply line for forming the thermosetting resin is connected to In addition to the combination of 4, 6.4 or A position each alone, or 3 and A or 4 and A or 3
, 4 and people can be arbitrarily selected.

However, since Kotobuki, most commonly it is a combination of 3 and 4.

[Brief explanation of drawings]

FIG. 1 is a graph showing the electromagnetic wave penetration and absorption behavior with respect to the mesh opening of the steel foil lath, and FIG. 2 is a conceptual diagram showing a composite material manufacturing line. 1.2...Last, 6,4...Resin liquid agent Patent attorney Sanro Kimura α force 1st figure ←j Lee → Ebisu 2nd m

Claims (2)

[Claims] (1) One or more precursors for forming a thermosetting resin such as an unsaturated linear polyester, a resol type phenol/formalin condensate, or a thermosetting epoxy resin;
A composite material characterized in that at least two laths of steel foil are electrically insulated from each other. (2) The composite material according to claim 1, which uses a lath that has been given electrical insulation by surface treatment.