JPH03290687A - Light-transmissive plate having electromagnetic wave shielding property - Google Patents

Abstract

PURPOSE:To shield electromagnetic waves and to improve the transparency, the antireflection property, and the durability by providing specified nonglare halogen coat layers on both faces of a plastic transparent base material and providing a transparent conductive film on one face of the halogen coated base material. CONSTITUTION:Nonglare hard coat layers essentially consisting of an organopolysiloxane are formed on both faces of the plastic transparent base material having >=70% all light transmittance. With respect to materials of these nonglare hard coat layers, various epoxy resin hardening agents or the like are used together with an organopolysiloxane as the essential component. An ITO film is formed as the transparent conductive film on one face of the plastic base material having nonglare hard coat layers by, for example, the sputtering method. Thus, this light-transmissive plate is superior in transparency and nonglare property and has a high surface hardness and has an excellent resistance to scratches, and the electromagnetic wave shielding property and the static electricity removing property are improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a light transmitting plate having electromagnetic wave shielding properties.

More specifically, it is capable of effectively blocking electromagnetic waves, and at the same time has excellent light transmittance, anti-reflection properties, and scratch resistance, and is particularly useful for displays such as liquid crystal displays (LCDs) and plasma displays (FDPs). It is suitable for blocking electromagnetic waves generated from computers, cordless phones, car phones, etc.

[Prior Art] Office automation equipment, such as word processors and displays of various computers, game consoles, and television cathode ray tubes, generate large amounts of harmful electromagnetic waves, which have been reported to cause health problems and other problems. Failure to equipment has become a problem. For example, it is often seen that a computer receives a false signal, or that when a TV and stereo are turned on at the same time, noise is heard from the stereo.

Therefore, various improvements have been made to eliminate such obstacles. An effective means is to cover it with a conductive material such as metal. For example, there are cases where carbon is adhered to the surface of thin fibers to form a mesh structure, and there are cases where thin metal wires are introduced inside laminated glass, such as Chori Co., Ltd.'s product name ``Eye Saver''. However, these methods have the disadvantage that they are difficult to see for users of word processors, etc., because they create areas that do not transmit light emitted from the display.

In addition, a technique has been proposed in which a conductive material is deposited at high temperature on a glass substrate (Japanese Patent Publication No. 18447/1983).
, when trying to apply this method to plastic substrates,
Many plastic base materials soften or melt,
In addition, the drawback that the surface is easily scratched cannot be improved and cannot be used.

For plastic transparent plates, JP-A-1-1310
Publication No. 1 discloses a method in which a non-glare hard-coated substrate made of a three-dimensional crosslinked polyfunctional acrylic material is used as a CRT filter, and a conductive film is provided thereon. However, this method requires transparency,
The adhesion between the hard coat film and the conductive film is poor, and the LCD
It could not be used for light-receiving type displays such as

In addition, the present applicant has already disclosed in Japanese Patent Application Laid-Open No. 62-215202 a technique for providing a hard coat layer with abrasion resistance on a transparent plastic curtain Murakami and further providing a conductive layer on a light transmitting plate having electromagnetic wave shielding properties. ing. However, since such a hard coat layer is not a layer having non-glare properties, it is insufficient in terms of antireflection properties.

[Problems to be Solved by the Invention] The present invention aims to solve the drawbacks of the above-mentioned prior art. In other words, it is possible to effectively block electromagnetic waves, and at the same time has excellent transparency, anti-reflection properties, and scratch resistance.
Furthermore, it is an object of the present invention to provide a light transmitting plate having excellent electromagnetic shielding properties and excellent durability due to excellent adhesion between layers.

[Means for Solving the Problems] As a result of intensive studies to achieve the above object, the present invention having the following configuration was completed.

[Electromagnetic shielding property characterized by providing a non-glare hard coat layer mainly composed of organopolysiloxane on both sides of a plastic transparent base material, and providing a transparent conductive film on at least one side of the hard coat base material A light transmitting plate with The plastic transparent base material in the present invention is not particularly limited as long as it has transparency, but substrates with a total light transmittance of 50% or more, particularly a total light transmittance of 70% or more are particularly suitable. preferable. Typical substrate components include poly(diethylene glycol bisallyl carbonate), polycarbonate, polymethyl (meth)acrylate, polyethylene terephthalate, polyether sulfone, polyether ether ketone, acrylonitrile-styrene copolymer, etc. . It is also preferable to use these substrates after subjecting the surface to coupling agent treatment, coating with a primer agent, chemical acid or alkali treatment, or various physical treatments depending on the use and purpose.

The non-glare hard coat layer in the present invention is mainly composed of organopolysiloxane, but the hardness of the coating film
In terms of strong adhesion to the transparent conductive film provided thereon, a mixture of one or more of the organosilicon compounds represented by the following general formula (A) and/or their hydrolyzed condensates may be used. A cured film containing an organopolysiloxane resin obtained by curing as a vehicle component is preferably used.

R' m R2S t Xa -0+.
(A) (In the formula, R1 and R2 are a hydrocarbon group having 1 to 6 carbon atoms or an organic group containing an amino group, an epoxy group, a mercapto group, or a methacryloxy group, X is a halogen, an alkoxy group, or an acyloxy group, and alb is 0.1 or 2, respectively, and a+b is 0.1 or 2).

Specific examples of the compound represented by the general formula (A) above include tetrafunctional silanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetrachlorosilane, methyltrimethoxysilane, methyltriethoxysilane, Methyltriptoxysilane, methyltrichlorosilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, phenyltrichlorosilane, N-(trimethoxysilylpropyl)ethylenediamine , aminomethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(3,4epoxycyclohexyl)ethyltrimethoxysilane, γ
- Trifunctional silanes such as mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, dimethylmethoxysilane, dimethyljethoxysilane, dimethyldichlorosilane, dimethyldiacetoxysilane, diethyldibutoxysilane, γ-glycidoxy Examples include bifunctional silanes such as propylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-glycidoxypropylmethyljethoxysilane. Hydrolysis is carried out using these compounds alone or in combination of two or more in the presence of an appropriate organic solvent and water, or in the presence of water alone. In this case, hydrolysis often proceeds effectively when a small amount of an acid such as hydrochloric acid is used in combination. At this time, condensation of some silanol produced during hydrolysis may normally occur, but this is not a particular problem as long as it does not lead to significant thickening or gelation.

In the non-glare hard coat layer of the present invention, a haze value of 3% or more can be preferably used for non-glare properties. What is the haze value here?
It means the value expressed as a 100% of the quotient obtained by dividing the diffuse transmittance measured according to K7105 by the total light transmittance. In the present invention, any method can be used to develop this haze value, including various conventionally known methods, but preferred methods include, for example: A method in which so-called silica sol, in which fine silica particles with a diameter of 5 nm to 1100 nm are dispersed colloidally in an organic solvent such as water and/or alcohol, is uniformly aggregated and dispersed in a vehicle by coexisting with an organic polymer such as polybutyral (for example, (Refer to Publication No. 61-54066), ■ The same silica sol as above and a particle size of 5 nm ~
Particle size 1, consisting of secondary aggregates of particles that are 50 nm, On
Examples include a method of uniformly dispersing fine silica powder of m to 5 Q nm (see, for example, JP-A-1-256576).

In the non-glare hard coat layer of the present invention, in addition to organopolysiloxane, which is the main component, curing acceleration,
Various curing agents can be used in combination to enable low-temperature curing. As the curing agent, various epoxy resin curing agents or various organosilicon resin curing agents are used.

Specific examples of these curing agents include various organic acids and their acid anhydrides, nitrogen-containing organic compounds, various metal complex compounds or metal alkoxides, and various salts such as organic carboxylates and carbonates of alkali metals. can be mentioned. It is also possible to use a mixture of two or more of these curing agents. Among these curing agents, the aluminum chelate compounds shown below are particularly useful for the purpose of the present invention in view of the stability of the coating material and the presence or absence of coloration of the coating film after coating.

The aluminum chelate compound mentioned here is, for example, -
Daito AIX,, Y3-. ．． This is an aluminum chelate compound represented by However, in the formula, X is OL (L is a lower alkyl group), Y is a ligand derived from a compound represented by the general formula (% lower alkyl group), and the general total M3COCH2COOM' (M3,
M4 is at least one ligand derived from a compound represented by a lower alkyl group, and n is 0.
, 1 or 2.

Various compounds can be used as the aluminum chelate compound represented by AIX, Y3-□, but aluminum acetylacetate is particularly preferred from the viewpoint of solubility in the composition, stability, and effect as a curing catalyst. aluminum di-n-butoxide-monoethyl acetoacetate, aluminum bisethyl acetoacetate, aluminum di-n-butoxide monoacetylacetoacetate, aluminum di-1
so-propoxide-monomethyl acetoacetate and the like. It is also possible to use a mixture of two or more of these.

The means for applying the non-glare hard coat layer on the plastic transparent substrate of the present invention include brush coating, dip coating,
Conventional application methods such as roll coating, spray coating, spin coating, and flow coating can be easily used.

In particular, when fine silica powder is used as the non-glare imparting component as described above, it is preferable to stir the coating composition before application in order to prevent the fine silica powder from settling. As for the stirring method, stirring using a simple stirring bar is possible, and a method that also performs stirring while performing circulation filtration is also preferable for the present invention.

The thickness of the non-glare hard coat layer is not particularly limited, but from the viewpoint of maintaining adhesive strength and hardness,
．． It is preferably used between 5 μm and 20 ttm. Particularly preferably, the thickness is 0.7 μm to 15 μm. In addition, when applying the coating composition, it is used after being diluted with various solvents for reasons such as workability and film thickness control. Examples of diluting solvents include water, alcohol, ester, ether, ketone, halogenated hydrocarbon, or toluene. A variety of aromatic solvents can be used depending on the purpose, and a mixed solvent can also be used if necessary.

In addition, when using the above-mentioned fine silica powder as a non-glare imparting component, it is possible to disperse it by stirring with a simple stirring blade, but in order to further improve the dispersion state, it is recommended to use paint conditioner. , a sand mill, a three-roll mill, a ball mill, a homomixer, a homogenizer, etc. are preferably used. From the viewpoint of reproducibility, homomixers and homogenizers are most preferably used. In addition, in order to maintain a stable dispersion state and improve the uniformity of the entire coating film, it is preferable to add various surfactants, such as silicone surfactants, fluorine surfactants, and organic surfactants. be done.

To form a film from these compositions, a coating composition containing these compositions is applied and then dried and cured by heating. The curing temperature varies depending on the compound selected and working conditions, but may range from 60°C to 300°C, or even 80°C.
C. to 200.degree. C. is preferably used. At lower temperatures, curing tends to be insufficient, and at higher temperatures, problems such as cracks and film decomposition may occur.

The above-mentioned non-glare hard coat layer is preferably provided on both sides of the plastic transparent base material in order to exhibit good hard coat properties, and furthermore, this non-glare hard coat layer is preferably provided on both sides of the plastic transparent substrate. It has the ability to improve the adhesion of

The transparent conductive film in the present invention may be any film as long as it can effectively block electromagnetic waves and can transmit visible light. In particular, when the film is mounted on a display such as a PDP or LCD, it is preferable that the film can obtain a total light transmittance of 50% or more. Preferred transparent conductive films include thin films made of metal oxides such as a mixture of indium oxide (In203) and tin oxide (Sn02) (hereinafter referred to as ITO), a mixture of tin oxide and antimony oxide, gold, silver, and nickel. , a metal thin film obtained from at least one kind of metal such as copper, chromium, or aluminum.

These thin films can be formed by a sputtering method, a thermal CVD method, an ion blasting method, a vacuum evaporation method, or the like. Particularly preferable transparent conductive films include a film made of ITO and a film made of 5n02 because of their excellent transparency. The thickness of the thin film may be any thickness as long as it produces such an effect, but it is selected appropriately from the viewpoint of transparency, adhesion, and economic efficiency. 100-300 in
It is A. When the film thickness is large, transparency deteriorates and cracks in the conductive film are likely to occur. If the film thickness is thin, electromagnetic shielding properties tend to deteriorate.

In the present invention, there is no problem in providing a single layer or multilayer antireflection layer on the surface of the conductive film for the purpose of antireflection. An example of a preferable layer is a layer containing silica. Such a silica layer can be obtained by sputtering or vacuum depositing silica. The film thickness can be appropriately selected within a range that can prevent reflection of visible light.

In order to prevent electromagnetic interference or remove static electricity, the light transmitting plate having electromagnetic wave shielding properties of the present invention has
Attaching a ground or attaching a frame using electromagnetic wave shielding material around it is also effective in achieving more effects. As for the material of the frame, metals such as copper foil and iron foil are preferable (metal plates such as galvanized iron plate, copper-plated iron plate, aluminum plate, etc., or metal materials such as copper mesh are preferable. When used, the surface of the frame may be sprayed with zinc, chemically plated with copper or nickel, or electroplated with copper or nickel.
A method such as applying a conductive paint containing metal powder such as nickel powder, copper powder, or silver powder is used.

It is also preferable to fill the plastic with metal, carbon, etc. in the form of flakes or fibers. It is preferable to keep these frames and the ground in contact with the conductive film or in a conductive state in order to prevent interruption loss.

The light transmitting plate having electromagnetic wave shielding properties of the present invention has transparency,
It has excellent non-glare, scratch resistance and durability, and can be particularly preferably used not only as a filter for CRT and flat display screens, but also for communication equipment (car phones, portable telephones, pagers, facsimiles, etc.). In particular, it is preferable to use it in close contact with the display surface as much as possible because resolution will not be reduced.

[Examples] In order to clarify the characteristics of the present invention, Examples are given below, but the present invention is not limited to these Examples.

Hereinafter, in the examples, "parts" indicate "parts by weight."

Example 1 A commercially available polymethyl methacrylate plate (“Acrylite” manufactured by Mitsubishi Rayon Co., Ltd., thickness 1.50) was used as a base material.
It was used.

272 parts of methyltrimethoxysilane was cooled to 10° C., and 108 parts of a 0.01N hydrochloric acid aqueous solution was added dropwise while stirring well. The dropwise addition is carried out while cooling so that the humidity does not exceed 10°C during the reaction. Similarly, vinylsylethoxysilane 1
Hydrolysis is carried out by dropping 54 parts of a 0.05N hydrochloric acid aqueous solution into 90 parts.

Further, 0.2 parts by weight of a curing catalyst, 0.05 parts by weight of a silicone surfactant, and a mixed solvent were added and dissolved with stirring. In order to further develop non-glare properties in this liquid, methanol-dispersed colloidal silica sol (manufactured by Nissan Chemical ■, solids concentration 3) was added.
0% by weight) and 1.5 parts of polyvinyl butyral resin (Tanezu Chemical Industry ■ product "S-LEC" BMS) were added and stirred to prepare a coating liquid. immersing the substrate in this coating liquid,
Coated. The material was cured by heating at 90° C. for 2.0 hours in a hot air dryer to obtain a plastic substrate having a non-glare hard coat layer.

An ITO film having a thickness of 700 mm was provided as a transparent conductive film on one side of the obtained plastic substrate having the non-glare hard coat layer by a sputtering method. The conditions of the sputtering method are indium-tin alloy (indium = 95
Using a magnetron sputtering device, a mixed gas of argon/oxygen was introduced using a magnetron sputtering device (200 SCCM of argon/10 SCCM of oxygen) using a magnetron sputtering device as a target.
) conditions. The surface specific resistance value of the obtained light transmitting plate was 100Ω/hole.

The performance of the obtained light transmitting plate was evaluated by the following method.

The results are shown in Table 1.

(a) Total light transmission rate: Measured according to JIS K7105G, m.

(b) Haze: Measured according to JIS K7105 and expressed as a percentage by dividing the diffuse transmittance by the total light transmittance.

(c) Surface gloss; gloss meter manufactured by Murayama Color Research Institute (
Type GM-3M) was used to measure the surface gloss at a 60° angle.

(d) Scratch resistance test: The coated surface was rubbed with #0000 steel wool under a load of 1.5 kg/al to examine the degree of scratching.

(e) Adhesion: 10x with a safety razor blade on the surface of the transparent plate.
100 cuts were made in 10 grids, and a cellophane adhesive tape ("Cellotape" manufactured by Chiban ■) was strongly applied and peeled off rapidly in a 90° direction to examine whether or not the paint film peeled off.

(f) Electromagnetic wave shielding: The electromagnetic wave shielding effect (d B) at a frequency of 10 GHx was determined using the following formula.

P.

P, is the incident electric field strength, P2 is the passing electric field Indicates strength.

Example 2 In Example 1, instead of using a transparent conductive film targeting an indium-tin alloy by sputtering, gold and silver were deposited by vacuum evaporation to a thickness of 50 mm (gold evaporation thickness: silver evaporation thickness = A light transmitting plate was obtained in the same manner as in Example 1 except that a transparent conductive film having a ratio of 1:2) was used. The surface specific resistance value was 13Ω/mouth.

The resulting light transmitting plate was a substrate with excellent transparency, scratch resistance, adhesion, and electromagnetic shielding properties. The results are shown in Table 1.

Example 3 A light transmitting plate was obtained in the same manner as in Example 1 except that the method for forming the non-glare hard coat film was replaced with the method described below.

100 parts of γ-glycidoxypropyltrimethoxysila = 7-hydrochloric acid hydrolyzate, 6 parts of aluminum acetylacetonate, 1.3 parts of fluorine surfactant, methanol-dispersed colloidal silica sol (manufactured by Catalyst Kasei ■ "08CAL-1")
132", solid content 30% by weight) and 12 parts of acetylacetone were added and thoroughly stirred and mixed. Furthermore, fine silica powder ("AERO8IL38" manufactured by Nippon Aerosil Co., Ltd.) was added and 12 parts of acetylacetone were added.
0'') was added and dispersed using a homogenizer to obtain a coating composition.

(2) A substrate made of commercially available “CR-39” (diethylene glycol bisallyl carbonate polymer), 1.5 mm, as a base material for producing a non-glare hard coat film.
As a pretreatment for thickness, the material was immersed in a caustic soda aqueous solution and then washed.

The substrate was coated by dipping the coating composition in (1) above, precured at 80° C. for 15 minutes in a hot air dryer, and then heated at 130° C. for 20 hours. The obtained coating film was 3. It was 0 μm.

The light transmitting plate thus obtained was a substrate with excellent transparency, scratch resistance, adhesion, and electromagnetic shielding properties.

The results are shown in Table 1.

Comparative Example 1 A light transmitting plate was obtained in the same manner as in Example 1, except that a conductive film was not provided and 50 parts of nickel particles with an average particle diameter of 2 μm were dispersed in a coating composition for forming a non-glare hard coat layer. . Although the electromagnetic wave shielding effect was good,
It had poor transparency and could not be used on a flat display. The results are shown in Table 1.

[Effects of the Invention] According to the present invention, it is possible to provide a light transmitting plate having electromagnetic wave shielding properties and having the following features.

1. Excellent transparency.

2. Excellent non-glare properties.

3. High surface hardness and excellent scratch resistance.

4. Excellent electromagnetic shielding and static electricity removal.

Claims (1)

[Claims] (1) Electromagnetic waves characterized by providing a non-glare hard coat layer mainly composed of organopolysiloxane on both sides of a plastic transparent base material, and providing a transparent conductive film on at least one side of the hard coat base material. A light transmitting plate with shielding properties.