JP2003298280A - Electromagnetic wave shielding plastic plate and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electromagnetic wave shielding plastic plate with high transparency for easily manufacturing the plate without using adhesive and to provide the plastic plate. <P>SOLUTION: A thermoplastic resin film having a conductive layer on a surface is arranged at a base part in a forming mold with the conductive layer up. A thermoplastic resin in a molted state is introduced on the layer. Then, it is cooled after introduction and the resin is frozen. Thus, the electromagnetic shielding plastic plate is manufactured. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding plastic plate useful as a front filter of a PDP (plasma display panel), a window material of a building requiring electromagnetic wave shielding such as a hospital, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, with the widespread use of OA equipment and communication equipment, there is a concern that the electromagnetic waves generated by these equipment may affect the human body. In addition, electromagnetic waves may cause malfunction of precision equipment, and electromagnetic waves are regarded as a problem.

Conventionally, a window material having an electromagnetic wave shielding property and a light transmitting property has been developed and put into practical use as a front filter of a PDP for OA equipment. As an electromagnetic wave shielding and light transmitting window material, an electromagnetic wave shielding plastic plate which does not use glass has been used. Such a window material such as a plastic plate is also used as a window material for a precision instrument installation place such as a hospital or a laboratory in order to protect the precision instrument from electromagnetic waves such as a mobile phone.

As such an electromagnetic wave-shielding light transmitting window material, a transparent film provided with a transparent conductive thin film containing metal silver, a transparent film provided with a conductive mesh in which metal wires or conductive fibers are reticulated, and transparent. A layer such as a copper foil on the film, which is etched to form a net and has an opening,
There is used a transparent film or glass on which a plating active species is formed in a specific shape, which is plated, and which is attached to a transparent substrate (glass plate or organic resin plate) with an adhesive.

For example, Japanese Patent Laid-Open No. 11-74681 discloses an electromagnetic wave shielding light transmitting window material in which a conductive mesh is integrated with an adhesive resin between two transparent substrates.

[0006]

The electromagnetic wave-shielding light-transmitting window material or the plastic plate disclosed in the above publication requires the formation of an adhesive layer in order to attach the conductive mesh film and the transparent substrate, Therefore, in order to obtain this plastic plate, two steps of an adhesive layer forming step and a transparent substrate attaching step are required. Further, since the refractive index of the conductive mesh film is different from that of the adhesive, and the adhesive and the thermoplastic resin plate (film) are different, reflection at the interface is large and sufficient transparency cannot be obtained. There is also a problem with.

Therefore, it is an object of the present invention to provide a method for producing an electromagnetic wave shielding plastic plate which can easily produce a highly transparent electromagnetic wave shielding plastic plate without using an adhesive.

Another object of the present invention is to provide an electromagnetic wave shielding plastic plate which is highly transparent and easy to manufacture.

[0009]

The above-mentioned problems can be solved by the inventors of the present invention who have made extensive studies.

According to the present invention, a thermoplastic resin film having a conductive layer on its surface is placed at the bottom of a molding die with the conductive layer side facing upward, and then the thermoplastic resin in a molten state is placed on the conductive layer. The method for producing an electromagnetic wave shielding plastic plate is characterized in that the electromagnetic wave shielding plastic plate is molded by introducing, pressurizing and cooling to solidify the resin.

The above-mentioned conductive layer is generally an alternating laminated body of a metal vapor deposition film and a dielectric film, a conductive mesh (wire mesh or the like), or a mesh pattern metal layer, a metal-containing resin layer or a metal-containing resin layer and a metal. A layered product, particularly a mesh-patterned metal layer, a metal-containing resin layer, or a laminate of the metal-containing resin layer and a metal layer is preferable.

It is preferable that the thermoplastic resin film and the molten thermoplastic resin are made of the same type of thermoplastic resin as the main material, and the same type of thermoplastic resin is polycarbonate. Alternatively, it is preferably an acrylic resin (particularly polymethyl methacrylate).

It is preferable that the molding die is a die for injection molding or compression molding.

The present invention also resides in an electromagnetic wave shielding and light transmitting window material obtained by the above manufacturing method.

Further, the present invention comprises a two-layer thermoplastic resin film and a conductive layer sandwiched between the thermoplastic resin films, and the materials mainly composed of these thermoplastic resins are the same type of thermoplastic resin. There is also an electromagnetic wave shielding plastic plate.

In the above plastic plate, the conductive layer is
In general, an alternating laminated body of a metal vapor deposition film and a dielectric film, a conductive mesh, or a metal layer in a mesh pattern, a metal-containing resin layer or a laminate of the metal-containing resin layer and a metal layer, particularly a mesh pattern A metal layer, a metal-containing resin layer, or a laminate of the metal-containing resin layer and the metal layer is preferable.
Further, the thermoplastic resin of the same type is preferably polycarbonate or acrylic resin (particularly polymethylmethacrylate).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The method for manufacturing an electromagnetic wave shielding plastic plate of the present invention can be carried out, for example, as follows.

FIG. 1 shows a schematic view of an example of the manufacturing method of the present invention. A film in which a conductive layer 2 having a mesh pattern is provided on a thermoplastic resin film 1 which is a transparent substrate is placed in a compression molding die (consisting of a frame and a lower die) 5. At that time, the thermoplastic resin film 1 is placed so that the conductive layer side faces up and the film contacts the lower mold surface of the mold. The thermoplastic resin 3 in a molten state is put on the conductive layer. The die 6 is lowered from above and the die is lightly sealed. afterwards,
Heating, pressurizing, etc. are performed by a usual method. The pressure is dropped (the temperature also drops), the mold is opened, and the electromagnetic wave shielding plastic plate 4 which is a molded product is obtained. The introduction of the molten thermoplastic resin can be performed by injection, extrusion, or various other methods. Conventionally, when pasting a thermoplastic resin on the conductive layer,
An adhesive layer was prepared, and the thermoplastic resin layer was attached to the conductive layer via the adhesive layer. However, according to the above method of the present invention, a thermoplastic resin layer having a smooth surface can be formed in one step without using an adhesive. In particular, this thermoplastic resin and the thermoplastic resin of the transparent substrate are If the same kind of resin is used, a laminate (plastic plate) having further excellent adhesiveness and transparency can be obtained, which is advantageous.

Although compression molding is used in FIG. 1, injection molding and cast molding can be performed in the same manner.
Further, the compression molding includes injection compression molding, stun bubble compression molding, sheet compression molding, vacuum compression molding, extrusion compression molding and the like, and can be used.

The thermoplastic resin film used in the electromagnetic wave shielding plastic plate of the present invention may be a resin film or sheet having transparency (particularly for visible light), and examples of the material include Polyester (eg, polyethylene terephthalate (PET), polybutylene terephthalate), acrylic resin (eg, polymethyl methacrylate (PMMA)), polycarbonate (PC), polystyrene, cellulose triacetate,
Polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyethylene, ethylene-vinyl acetate copolymer, polyvinyl butyral, metal ion cross-linked ethylene-
Methacrylic acid copolymer, polyurethane, cellophane and the like can be mentioned. Among these, processing (heating,
PET, PC, and PMMA, which are highly transparent materials with little deterioration due to solvent and bending, are preferable.

Although the thickness of the thermoplastic resin film varies depending on the use of the electromagnetic wave shielding and light transmitting window material,
Usually in the range of 1 μm to 5 mm, especially 10 μm to 1 m
It is preferably in the range of m.

A conductive layer is provided on the thermoplastic resin film, and the thermoplastic resin in a molten state applied on the conductive layer may be made of the same material as that of the film.

In the present invention, it is preferable that the film and the resin of the thermoplastic resin in the molten state are of the same type. In particular, both are preferably acrylic resin (particularly polymethylmethacrylate) or polycarbonate.

The conductive layer provided on the thermoplastic resin film may have any form. For example,
Alternating stack of metal evaporated film and dielectric film, wire mesh,
Alternatively, a metal layer or metal-containing resin layer in a mesh pattern, a metal-patterned resin layer in a mesh pattern, and a laminated body of metal layers provided thereon can be cited.

The alternate laminated body of the metal vapor deposition film and the dielectric film is obtained by alternately laminating a metal thin film of silver, copper or the like and a dielectric film of SiO2 or the like. The number of layers is generally about 2 to 7.

Examples of the conductive mesh such as wire mesh include the following.

That is, the conductive mesh has a wire diameter of 1 μm to 1 m made of metal fibers and / or metal-coated organic fibers.
m and an aperture ratio of 50 to 90% are common. In this conductive mesh, if the wire diameter exceeds 1 mm, the aperture ratio is lowered, or the electromagnetic wave shielding property is lowered, and it is not possible to satisfy both requirements. If it is less than 1 μm, the strength of the mesh is lowered and the handling becomes very difficult. Further, if the aperture ratio exceeds 90%, it is difficult to maintain the shape of the mesh, and if it is less than 50%, the light transmittance is impaired. More preferable wire diameter is 10 to 500 μm, and opening ratio is 60 to 90%
Is. The aperture ratio of the conductive mesh means the area ratio of the opening portion in the projected area of the conductive mesh.

The metals of the metal fibers and the metal-coated organic fibers constituting the conductive mesh include copper, stainless steel, aluminum, nickel, titanium, tungsten, tin, lead,
Iron, silver, carbon or their alloys, preferably copper, stainless steel or aluminum are used.

As the organic material of the metal-coated organic fiber, polyester, nylon, vinylidene chloride, aramid, vinylon, cellulose and the like are used.

As the mesh-patterned metal layer, a conductive foil such as a metal foil is generally pattern-etched.

In this case, as the metal of the metal foil, copper, stainless steel, aluminum, nickel, iron, brass, or an alloy thereof, preferably copper, stainless steel or aluminum is used.

If the thickness of the metal foil is too thin, it is not preferable in terms of handleability and workability of pattern etching, and if it is too thick, it affects the thickness of the glass to be obtained, and the time required for the etching process is long. From 1 to 20
It is preferably about 0 μm.

The method of pattern etching such a metal may be any method generally used, but photoetching using a resist is preferable. In this case, after coating the photoresist on the metal foil, pattern exposure is performed using a desired mask, and then development processing is performed to form a resist pattern. After that, the metal foil in the portion without the resist may be removed with an etching solution such as ferric chloride solution.

According to the pattern etching, the degree of freedom of the pattern is large, and the metal foil can be etched into an arbitrary wire diameter, interval and hole shape. Therefore, a glass having a desired electromagnetic wave shielding property and light transmitting property can be obtained. It can be easily formed.

The shape of the etching pattern is not particularly limited, and may be, for example, a grid-shaped metal foil in which square holes are formed, or a punching metal shape in which circular, hexagonal, triangular or elliptical holes are formed. Metal foil etc. are mentioned. Further, the holes are not limited to being regularly arranged, but may be a random pattern.

As an alternative to the above mesh pattern metal layer, a mesh pattern metal containing resin layer, or a laminate of a mesh pattern metal containing resin layer and a metal layer provided thereon may be used. it can. The mesh-patterned metal-containing resin layer is obtained, for example, by forming a resin layer (ink layer) containing conductive fine particles in a mesh pattern by printing or the like. If necessary, metal plating may be further applied thereon to obtain a laminate of the metal-containing resin layer and the metal layer.

The metal-containing resin layer has a thickness of 0.1 to 20 μm.
m, particularly preferably 0.5 to 5 μm. 0.1
If it is thinner than μm, the curability is poor, and if it is thicker than 20 μm, it is difficult to obtain a fine wire.

The line width of the conductive layer of the mesh pattern thus formed is generally preferably 20 μm or less. Also,
The aperture ratio is preferably 75 to 95%, and particularly 80
~ 95%. The aperture ratio is the mesh line width and 1
It is calculated from the number of lines existing in the inch width.

The shape of the opening surrounded by the line is circle, ellipse,
Although it may have any shape such as a prism, it is preferably a prism, and particularly preferably a square. Further, the lines have a mesh shape, but it is preferable that the lines have a grid shape.

When it is desired to further lower the resistance value and enhance the electromagnetic wave shielding effect, it is preferable to form a plating layer on the conductive layer. In this case, the thickness of the conductive layer can be suppressed to a low value.

As the material used for the plating treatment,
Mention may be made of copper, nickel, chromium, zinc, tin, silver and gold. These may be used alone or as an alloy of two or more. The plating treatment is generally performed by ordinary liquid phase plating (electrolytic plating, electroless plating, etc.).

The thickness of the plating layer is generally 0.1 to 10 μm.
The range of m, 2-5 micrometers is preferable. If the thickness is less than 1 μm, the electromagnetic wave shielding effect is not sufficiently imparted, and if it exceeds 10 μm, the plating layer tends to spread in the width direction and the line width tends to be thick.

In the method for producing an electromagnetic wave shielding plastic plate of the present invention, a step for providing another layer such as an antiglare layer may be further performed if desired. The antiglare layer can be formed by, for example, blackening treatment, that is, oxidation treatment of a metal film, black plating of a chromium alloy or the like, application of black or dark color ink.

According to the present invention, the thermoplastic resin film provided with the conductive layer obtained as described above is coated with the thermoplastic resin in a molten state to cover the electromagnetic wave shielding plastic plate of the present invention. Obtainable. In the present invention, in order to cover the conductive layer with the molten thermoplastic resin, it is molded using a mold.

In the present invention, as illustrated in FIG.
When molding a plastic plate using a mold, it is preferable to carry out compression molding. Generally, molding is performed at a pressure of 50 to 3
It is performed under the conditions of 00 MPa and a temperature of 100 to 350 ° C.
Thermoplastic resin film and molten thermoplastic resin,
When both polycarbonates are used, the pressure is 60-18
The conditions are preferably 0 MPa and a temperature of 200 to 300 ° C. When both polymethylmethacrylates are used, the pressure is preferably 70 to 250 MPa and the temperature is 150 to 300 ° C. Various methods can be used as means for charging the molten thermoplastic resin into the mold. For example, extrusion molding, injection molding, stamping molding, sheet molding, vacuum molding and the like can be used.

The thickness of the obtained electromagnetic wave shielding plastic plate is generally 0.1 to 10 mm, preferably 1 to 5 mm.

The electromagnetic wave shielding plastic plate integrally molded by the manufacturing method of the present invention can be obtained in a single molding step without using an adhesive layer, and the obtained plastic plate has a surface. And the inside is homogeneous. Therefore, it can be said that the electromagnetic wave shielding plastic plate of the present invention can be easily manufactured, has a uniform surface, and is excellent in transparency. Moreover, an electromagnetic wave shielding plastic plate using a thermoplastic resin (film) above and below the conductive layer has never been obtained,
It can be called a new window material.

The electromagnetic wave shielding plastic plate of the present invention is excellent in electromagnetic wave shielding property and transparency as described above. Therefore, the electromagnetic wave shielding plastic plate of the present invention is suitable as a front filter for a plasma display (PDP), and is also used as a window material (for example, a sticking film) for buildings such as hospitals that require electromagnetic wave shielding properties. Can be used advantageously.

[0049]

EXAMPLES The present invention will be specifically described with reference to the following examples. [Example 1] A 200 μm-thick polycarbonate film having a copper foil formed on the surface was coated with a photoresist on the copper foil, dried, and then exposed to a resist layer through a mesh-patterned mask and developed. Then, etching treatment was performed. Thereby, the conductive layer (mesh pattern metal layer: thickness 10 μm, line width 10 μm, line pitch 300 μm)
m, opening ratio 90%) to obtain a polycarbonate film.

Using the compression molding machine, the film with the conductive layer was placed in the mold of the compression molding machine. At that time, the film was placed in contact with the lower surface of the mold. 2 on the conductive layer
A molten polycarbonate heated to 00 ° C. was charged, and a pressure of 100 MPa was applied. Then, the pressure was dropped (the temperature also dropped), the mold was opened, and an electromagnetic wave shielding plastic plate (thickness: 3 mm), which was a molded product, was obtained.

COMPARATIVE EXAMPLE 1 A 188 μm-thick polycarbonate film having a copper foil formed on its surface was coated with a photoresist on the copper foil, dried, and then exposed through a mask having a mesh pattern to expose the resist layer. , Developed and then etched. Thus, a polycarbonate film having a conductive layer (mesh pattern metal layer: thickness 10 μm, line width 10 μm, line pitch 300 μm, aperture ratio 90%) was obtained.

A urethane adhesive was applied onto the conductive layer of the above-mentioned film with a conductive layer, and a polycarbonate plate having a thickness of 2.8 mm was attached thereto to obtain an electromagnetic wave shielding plastic plate (thickness of 3 mm).

The following physical properties of the obtained electromagnetic wave shielding plastic plate were measured. 1) Light transmittance (wavelength region of 380 to 800 nm) One optical information recording substrate is set to 3 according to JIS-K6717.
The light transmittance in the wavelength region of 80 to 800 nm was measured. 2) Parallel light transmittance (wavelength region of 380 to 800 nm) One optical information recording substrate is set to 3 according to JIS-K6717.
The parallel light transmittance in the wavelength range of 80 to 800 nm was measured. 3) Haze Measured according to JIS-K6900. 4) Surface resistivity (Ω / □) The surface resistivity of the obtained window material on the conductive layer or the plating layer was measured by a four-terminal method using Loresta AP (manufactured by Mitsubishi Chemical Corporation). 5) Electric field shield effect (dB) The window material was cut into 15 × 15 cm and measured by the KEC method under the condition of a frequency of 100 MHz. A shield property evaluation device (manufactured by Anritsu Corporation) was used for the measurement. 6) Magnetic field shield effect (dB) The magnetic field shield effect was measured in the same manner as the measurement of the electric field shield effect. 7) Aperture ratio (%) Hitachi spectrophotometer (U-4000; manufactured by Hitachi, Ltd.)
Was used to measure the light transmittance at a wavelength of 550 nm, and the reflection loss at the air interface was canceled to obtain the aperture ratio.

The parallel light transmittance of Example 1 was higher than that of Comparative Example 1, and the haze of Example 1 was lower than that of Comparative Example 1,
The electromagnetic wave shielding plastic plate of Example 1 was excellent in transparency. The light transmittance of the example was 80%.

The light transmittance, surface resistivity, electric field shield effect, magnetic field shield effect, and aperture ratio were almost the same.

[0056]

The electromagnetic wave shielding plastic plate integrally molded using the manufacturing method of the present invention can be obtained by a single molding step without using an adhesive layer,
Moreover, the obtained plastic plate is homogeneous both on the surface and inside. Therefore, it can be said that the electromagnetic wave shielding plastic plate of the present invention can be easily manufactured, has a uniform surface, and is highly transparent. For this reason,
The electromagnetic wave shielding plastic plate of the present invention is suitable as a front filter of a plasma display panel (PDP), and is advantageous as a window material (for example, a sticking film) of a building such as a hospital that needs electromagnetic wave shielding property. Can be used for

[Brief description of drawings]

FIG. 1 is a schematic view for explaining an example of a method for manufacturing an electromagnetic wave shielding plastic plate of the present invention.

[Explanation of symbols]

1 Thermoplastic resin film 2 mesh pattern conductive layer 3 Thermoplastic resin 4 Electromagnetic wave shielding plastic plate 5 Mold for compression molding 6 die

Claims (13)

[Claims] 1. A thermoplastic resin film having a conductive layer on its surface is placed at the bottom of a molding die, with the conductive layer side facing upward, and then the molten thermoplastic resin is introduced onto this conductive layer. Then, the method for producing an electromagnetic wave shielding plastic plate is characterized by molding the electromagnetic wave shielding plastic plate by pressing and then cooling to solidify the resin. 2. The conductive layer comprises an alternating laminate of a metal vapor deposition film and a dielectric film, a conductive mesh or a mesh pattern metal layer, a metal-containing resin layer, or a laminate of the metal-containing resin layer and a metal layer. The method for producing an electromagnetic wave shielding plastic plate according to claim 1, wherein 3. The electromagnetic wave shielding plastic plate according to claim 1, wherein the conductive layer is a mesh-patterned metal layer, a metal-containing resin layer, or a laminate of the metal-containing resin layer and the metal layer. Method. 4. The method according to claim 1, wherein the thermoplastic resin film and the thermoplastic resin in a molten state are thermoplastic resins of which the main materials are the same. 5. The method according to claim 4, wherein the same type of thermoplastic resin is polycarbonate. 6. The method according to claim 4, wherein the same type of thermoplastic resin is an acrylic resin. 7. The method according to claim 1, wherein the molding die is a mold for injection molding or compression molding. 8. An electromagnetic wave shielding plastic plate obtained by the manufacturing method according to claim 1. 9. An electromagnetic wave shielding property comprising a two-layer thermoplastic resin film and a conductive layer sandwiched between the thermoplastic resin films, and the main materials of these thermoplastic resins are the same kind of thermoplastic resin. Plastic plate. 10. The conductive layer comprises an alternating laminate of a metal vapor deposition film and a dielectric film, a conductive mesh or a mesh pattern metal layer, a metal-containing resin layer, or a laminate of the metal-containing resin layer and a metal layer. 10. The electromagnetic wave shielding plastic plate according to claim 9. 11. The electromagnetic wave shielding plastic plate according to claim 9, wherein the conductive layer is a mesh pattern metal layer, a metal-containing resin layer, or a laminate of the metal-containing resin layer and the metal layer. 12. The electromagnetic wave shielding plastic plate according to claim 9, wherein the same kind of thermoplastic resin is polycarbonate. 13. The electromagnetic wave shielding plastic plate according to claim 9, wherein the same kind of thermoplastic resin is an acrylic resin.