JPS61225013A - Perspective electromagnetic wave shield material and its preparation - Google Patents

Abstract

PURPOSE:To form a sharp perspective image having no distortion, by embedding metal plated synthetic fiber cloth in an acrylic resin molded body. CONSTITUTION:A shield plate 1 is integrally molded from an acrylic resin 2 and metal plated synthetic fiber cloth 5 is embedded between one surface 3 and the other surface 4. Two resins are divided by the fiber cloth 5 is connected through the apertures of the cloth 5 to be perfectly integrated and there is perfectly or almost no void gaps in the resin matrix or the interface of the resin and the metal plated layer. Because the synthetic fiber cloth 5 being a conductive net has flexibility and easy deformability even when a molded body having a relatively large dimension, the deformation at the time of molding, the generation of internal stress and strain and the generation of cracks are prevented by this structure and, because a monofilament with a small diameter is easily obtained as a synthetic fiber and the strand itself of the conductive net can be made fine, a transparent shield plate having no feeling of physical disorder in a case used in OA machinery or a CRT filter is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electromagnetic wave shielding material that has excellent transparency and little optical distortion, and a method for manufacturing the same, and more particularly relates to deformations such as warping and bending during molding. The present invention relates to an electromagnetic wave shielding material that has no internal strain and internal stress, and has excellent clarity in transparent images, and a method for manufacturing the same.

Prior Art and Technical Problems of the Invention In recent years, with the advanced development of office automation equipment and other electronic devices, they have become effective in shielding electromagnetic waves from the viewpoint of preventing noise in electronic equipment and preventing the direct influence of electromagnetic waves on the human body. ,
In addition, transparent electromagnetic shielding plates are desired for use as CRT filters for office automation equipment, viewing windows for shielded rooms for electronic equipment, and the like.

Conventionally, such transparent electromagnetic wave shielding plates include: ■ Porous metal plates such as punched metal; ■ Articles in which transparent materials are coated with conductive metal oxides or metals by vacuum deposition, etc.; ■ Conductive synthetic fiber networks. ■ Wire mesh made of stainless steel, etc. However, with ■, the shielding effect tends to decrease over time due to corrosion, etc., with ■ it is difficult to obtain a sufficient shielding effect, and with ■ it is relatively easy to obtain. However, the strength is not sufficient, and it is difficult to clean the screen from tearing, corrosion, and attached dirt, and the method (2) has the following disadvantages: it is difficult to obtain a filament with a small diameter.

Outline and Purpose of the Invention The present invention provides a radically polymerizable acrylic resin syrup containing:
Among various porous conductive materials, by embedding metal-plated synthetic fiber gauze and polymerizing the syrup, there is no deformation such as warping during polymerization, and no internal strain or internal stress is generated. It has been found that it is possible to obtain an electromagnetic wave shielding material that can suppress electromagnetic waves and form clear perspective images without distortion.

That is, an object of the present invention is to provide an electromagnetic wave shielding material that eliminates the above-mentioned drawbacks of conventional electromagnetic wave shielding materials.

Another object of the present invention is to provide a transparent electromagnetic wave shielding material that has excellent transparency and electromagnetic wave shielding properties, eliminates deformation and internal distortion during molding, and does not cause distortion of transparent images. It is in.

Still another object of the present invention is to provide a see-through electromagnetic wave shielding material and a method for manufacturing the same, which eliminates the aforementioned deformation and internal distortion that tend to occur when acrylic resin syrup is used as a laminating resin for porous conductive members. It is on offer.

According to the present invention, there is provided a see-through electromagnetic wave shielding material characterized in that at least one sheet of metal-plated synthetic twill fiber is embedded in an acrylic resin molded body.

According to the present invention, radically polymerized acrylic syrup is injected into a mold in which a metal-plated synthetic fiber gauze is spread and fixed in the inner space, and the acrylic resin and the gauze are integrated by polymerizing the syrup. Provided is a method for producing a see-through electromagnetic shielding material, which comprises obtaining a molded article.

Preferred Embodiment of the Invention In FIG. 1 showing the cross-sectional structure of the electromagnetic wave shielding material of the present invention, the shielding plate 1 is integrally molded with acrylic resin 2, and there is a metal between one surface 3 and the other surface 4. A plated synthetic fiber gauze 5 is embedded, and the two resins partitioned by the metal plated synthetic fiber gauze are connected through the openings of the gauze 5 and are completely integrated. That is, the acrylic resin 2 and the metal-plated synthetic fiber gauze 5 are completely adhered and integrated, and there are no or almost no voids in the resin matrix or the interface between the resin and the metal-plated layer.

When forming a laminate structure between a conductive porous member and an acrylic resin, the conductive porous member is sandwiched between two pre-formed acrylic resin plates, and then hot pressing, ultrasonic welding,
It is possible to integrate the two resin plates by bonding with adhesive, etc., but in this case, a fine gate will always remain between the conductive member and the resin, making it difficult to completely integrate them. It is difficult to separate the two, and peeling may occur at the interface between the two, or image distortion may occur at the interface.

According to the present invention, all of the above-mentioned drawbacks are solved by using radically polymerizable acrylic syrup, embedding metal-plated synthetic fibers in the syrup, and polymerizing and integrating the fibers.

That is, the electromagnetic wave shielding material 1 of the present invention, as shown in FIG.
For example, a metal-plated synthetic fiber gauze 5 is fixed in a liquid-tight manner to the center of sheet-like molds 6 and 7 made of reinforced glass or the like via a sweeter or gasket 8.8 that can follow shrinkage during polymerization and hardening. , is obtained by injecting a composition containing an acrylic monomer, an acrylic resin prepolymer, and a radical polymerization initiator into this space 9, and polymerizing this composition while heating.

The radical polymerizable acrylic resin syrup is a syrup-like liquid composition containing an acrylic resin prepolymer and an acrylic monomer. A preferred acrylic resin syrup is based on methyl methacrylate.

This methacrylic resin syrup is obtained by adding a small amount of a radical polymerization initiator to a monomer mainly composed of methyl methacrylate, heating the mixture in a prepolymerization tank, and partially polymerizing the mixture. The degree of partial polymerization is suitably within a range such that the polymerization rate is 10 to 30%. Before or after partial polymerization, for the purpose of moldability and resin modification,
styrene.

Styrenic monomers such as vinyltoluene and other acrylic monomers such as ethyl acrylate and butyl methacrylate can be mixed. These modifying monomers are used in an amount of 10 to 30 i[!] per syrup. : It is best to use within the range of quantity.

The raw material resin syrup has a molecular weight of 500 to 2000 in terms of mixability with the components described later, castability, and post-polymerization curability.
It is desirable to have a viscosity of centipoise (CPS). This syrup is mixed with a radical initiator and used for molding.

As a radical initiator, benzoyl peroxide,
Organic peroxides such as lauryl and +41-oxide and azo compounds such as azobisisobutyronitrile are used.
These initiators are present in so-called catalytic amounts, generally from 0.05 to 2% by weight, especially from 0.2 to 2% by weight, based on the resin syrup.
used in amounts of

The casting composition of the present invention may contain known auxiliary agents or compounding agents, such as coloring agents, viscosity modifiers, antioxidants, mold release agents, etc., to the extent that their essence is not impaired. It can be formulated in a prescription.

In the present invention, metal plated synthetic 9 fiber gauze is used in combination with the above-mentioned resin. Metal-plated synthetic fiber gauze is obtained by weaving or knitting monofilament, multifilament yarn, or spun yarn of polyester, nylon, vinylon, acrylic, etc. into a coarse weave.
Copper, nickel.

A plated layer of metal such as cobalt, chromium, silver, or aluminum is used. The formation of the plating layer is
It is performed by electroless plating (chemical plating), vacuum deposition, or a combination of these and electroplating. The plating layer may be formed to such an extent that these surfaces become sufficiently conductive but do not cause clogging. The plating layer may be a single metal island or may be composed of layers of multiple types of metals, for example, a combination of an electroless plating layer and an electrolytic plating layer is used. The metal-plated synthetic fiber used in the present invention has a mesh size of 80 to 250, particularly 100 to 2.
It is desirable to have a mesh of approximately 0.00 mesh from the viewpoint of electromagnetic wave shielding properties and light transmittance, and it is desirable that the aperture ratio is generally in the range of 10 to 90 inches, particularly 30 to 80 inches.

According to the present invention, by using metal-plated synthetic fiber gauze as the conductive mesh, extremely large advantages are achieved in relation to molding shrinkage of resin, etc. In other words, the molding shrinkage rate of methacrylic resin is on the order of about 20%, but when using metal netting, punching metal, etc. for VC, it is difficult for the resin to shrink in the areas where the conductive netting is provided, and in other areas. Since the resin contracts, internal strain or internal stress occurs.

For example, in a portion where the conductive network is deviated from the center of the resin molded body, deformation such as curvature easily occurs. Furthermore, during use or when exposed to heat, cracks are likely to occur and transparency may be impaired.

On the other hand, according to the present invention, even when producing a relatively large-sized molded object, the synthetic fibers that form the base of the conductive network have flexibility and easy deformability, so that they are resistant to shrinkage during resin curing. The followability is good, and deformation such as curvature during molding, generation of internal stress and internal strain, and accompanying cracks can be effectively prevented.

Moreover, with synthetic fibers, monofilaments with small diameters can be easily obtained, and the strands of the conductive network themselves can be extremely fine, so when used in applications such as office automation equipment and CRT filters, they are transparent and look strange ( You can get something that doesn't cause an eyesore.

Further, this metal-plated synthetic fiber gauze itself has good workability such as cuttability, and the molded body in which it is embedded also has good workability. Furthermore, this material also has the advantage of good followability when bending is performed.

In the electromagnetic shielding material of the present invention, since the metal-plated synthetic fiber gauze has good shrinkage followability, the position where it is buried is not particularly limited; for example, it may be located in the center of the molded body, or it may be placed in any It may be provided offset to the surface side. Moreover, two or more sheets of metal-plated synthetic fiber gauze can be provided if desired. The metal plating layer may be colored if desired. Furthermore, in order to improve the adhesion with the resin,
The surface of the metal-plated synthetic resin gauze may be previously treated with a coupling agent such as Trie or toxiaminopropysilane. Further, it may be dyed black for the purpose of removing metallic color.

Polymerization can be carried out by any method known per se,
For example, a one-stage polymerization method or a two-stage polymerization method may be used. For example, in the latter two-stage polymerization method, a method may be employed in which the first stage is a polymerization at a relatively low temperature, and the second stage is a combination of polymerization at a higher temperature.

Further, for the purpose of removing internal strain caused by polymerization shrinkage, heat treatment can be performed at a temperature equal to or higher than the glass transition temperature (Ti 2 ) of the resin.

The electromagnetic wave shielding material according to the present invention has an excellent electromagnetic wave shielding function,
Moreover, not only can it be seen through, but because it is manufactured using a cell-casting method, it is completely integrated with the conductive net, and unlike products made by welding or adhesive processing, there is no peeling, minute artifacts, or image distortion. There is no risk of this occurring. Also, since it is made of resin, it can easily provide functions other than shielding electromagnetic waves, such as blocking UV light.

In addition, by forming a plate in which conductive fiber gauze is embedded in acrylic resin with excellent properties, the above-mentioned corrosion can be prevented.
An electromagnetic wave shielding material that eliminates problems such as screen tearing, is easy to clean, is uniform as a whole, and does not feel strange when used as a CRT filter for office automation equipment is provided.

Example 0.1% by weight of benzoyl chloride in methyl methacrylate
Oxide was added and heated to 80° C. in a prepolymerization pot to produce an acrylic resin film (viscosity 1000 cps) with a polymerization rate of about 25 cm. A casting composition was prepared by blending 0.5ifi% of penzoylno or monooxide into this resin base. This composition was molded into an electromagnetic shielding plate using the mold shown in FIG. An electromagnetic wave shielding net consisting of a 200-mesh polyester fiber monofilament gauze coated with copper in a non-clogging state is placed under uniform tension. Next, a gasket was placed on each peripheral edge of two 400i square glass plates, and the electromagnetic shielding net was inserted and clipped to form a gap of % 3 vy'm.

The defoamed casting composition was injected through an injection port provided at the top of the gasket, and polymerized and cured at 80° C. for 3 hours.

The obtained electromagnetic wave shielding plate has no deformation such as curvature, has excellent transparency, and when used as a filter,
It was completely unobtrusive.

Effects of the Invention According to the present invention, a metal-plated synthetic fiber gauze is used as a conductive net for an acrylic resin molded body, and by embedding it in the resin, deformation such as warping and internal distortion during molding can be prevented. An electromagnetic wave shielding material is provided that effectively prevents the generation of internal stress, has excellent transparency, is free from image distortion, and has excellent magnetic properties.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a transparent electromagnetic wave shielding material according to the present invention, and FIG. 2 is an explanatory diagram for explaining the production of the electromagnetic wave shielding material of the present invention. 1 is electromagnetic wave shielding material, 2 is acrylic resin, 3 and 4 are surfaces,
5 is a metal-plated synthetic fiber gauze, 6 and 7 are molds, and 8 is a gasket. Patent applicant: Fukubi Chemical Industry Co., Ltd. Figure 1 Figure 2

Claims (3)

[Claims] (1) A transparent electromagnetic wave shielding material characterized by having at least one sheet of metal-plated synthetic fiber gauze embedded in an acrylic resin molded body. (2) The shielding material according to claim 1, wherein the metal-plated synthetic fiber gauze has a mesh of 80 to 250 mesh. (3) A radically polymerized acrylic syrup is injected into a mold in which the metal-plated synthetic fiber gauze is spread and fixed in the inner space, and the syrup is polymerized to form a molded body in which the acrylic resin and the gauze are integrated. A method for producing transparent electromagnetic shielding material comprising obtaining.