JPH1174683A - Electromagnetic wave shielding light transmission window material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good electromagnetic wave shielding capability and enable realization of a light transmissive sharp image, by forming a transparent conductive film on one side or both sides of at least one of two transparent substrates. SOLUTION: Two transparent substrates 2A and 2B are bonded and integrated by an adhesive resin 4 with a conductive mesh 3 provided between these substrates. On the surface of the transparent substrate 2A located on the side opposite to the electromagnetic wave source, that is, on the surface which becomes the inner side of an equipment in the case where a window frame 1 is used as a front filter of a PDP, a transparent conductive film 5 is formed. As the transparent conductive film 5, a thin film of ITO, ZnO, ZnO doped with Al, SnO2 or the like can be formed. Thus, good electromagnetic wave shielding property and light transmissiveness can be provided, and a moire phenomenon generated between this device and a matrix of a display can be reduced.

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 light transmitting window material, and more particularly to an electromagnetic wave having good electromagnetic wave shielding and light transmitting properties, which is useful as a front filter of a plasma display panel (PDP). The present invention relates to a light transmitting window material having a shielding property.

[0002]

2. Description of the Related Art In recent years, with the spread of office automation equipment and communication equipment, electromagnetic waves generated from these equipment have become a problem. That is, there is a concern that the electromagnetic waves may affect the human body, and malfunctions of precision equipment due to the electromagnetic waves have become a problem.

Therefore, as a front filter of a PDP of an OA device, a window material having an electromagnetic wave shielding property and a light transmitting property has been conventionally developed and put to practical use. Such a window material is also used as a window material in a place where precision equipment is installed, such as a hospital or a laboratory, in order to protect precision equipment from electromagnetic waves such as mobile phones.

The conventional electromagnetic wave shielding light transmitting window material has a structure in which a conductive mesh material such as a wire mesh is interposed between transparent substrates such as an acrylic plate.

[0005]

However, the electromagnetic wave shielding light transmitting window material using the conventional conductive mesh cannot provide a sufficient electromagnetic wave shielding property, and the mesh of the mesh is considerably fine. OA equipment P
Since a grid-like object will be placed in front of the DP,
Phenomena such as blurred images occur, and clear images cannot be obtained, and interference fringes (so-called moiré) occur between the number of dots of the PDP and the grid of the mesh. There was a problem of becoming.

[0006] The present invention solves the above-mentioned conventional problems and provides a PD.
It is an object of the present invention to provide an electromagnetic-shielding light-transmitting window material which has good electromagnetic-wave shielding performance, is suitable as an electromagnetic-wave shielding filter for P, and can obtain a transparent image with a clear image.

[0007]

The electromagnetic shielding light transmitting window material of the present invention is an electromagnetic shielding light transmitting window formed by integrally bonding an adhesive resin with a conductive mesh interposed between two transparent substrates. The material is characterized in that a transparent conductive film is formed on one or both surfaces of at least one of the two transparent substrates.

In the electromagnetic wave shielding light transmitting window material of the present invention, since a transparent conductive film is formed, excellent electromagnetic wave shielding properties can be obtained with the transparent conductive film and the conductive mesh. Thus, in order to obtain electromagnetic wave shielding properties in combination with a transparent conductive film, in the design of a conductive mesh,
The moiré phenomenon can be emphasized, and a mesh design with less moiré phenomenon can be realized.

Since the electromagnetic wave shielding light transmitting window material of the present invention has the conductive mesh interposed between the transparent substrates as described above, the scattering prevention effect at the time of breakage can be obtained.
High safety.

In the present invention, ethylene-vinyl acetate copolymer (EVA) is preferred as the adhesive resin.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electromagnetic wave shielding light transmitting window material of the present invention will be described below in detail with reference to the drawings.

FIGS. 1A to 1C are schematic sectional views showing an embodiment of an electromagnetic wave shielding light transmitting window material of the present invention.

An electromagnetic wave shielding light transmitting window material 1 shown in FIG. 1A is composed of two transparent substrates 2A and 2B,
And the surface of the transparent substrate 2A located on the opposite side to the electromagnetic wave generation source, that is,
When the window material 1 is used as a front filter of a PDP,
A transparent conductive film 5 is formed on a surface that is to be the front side of the device.

An electromagnetic wave shielding light transmitting window material 1A shown in FIG. 1B is formed by integrally joining two transparent substrates 2A and 2B with an adhesive resin 4 with a conductive mesh 3 interposed therebetween. On the bonding surface of the transparent substrate 2A located on the opposite side to
A transparent conductive film 5 is formed.

The electromagnetic wave shielding light transmitting window member 1B shown in FIG. 1C is formed by integrally joining two transparent substrates 2A and 2B with an adhesive resin 4 with a conductive mesh 3 interposed therebetween. The transparent conductive film 5 is formed on the bonding surface of the transparent substrate 2B located on the side.

Although not shown, the transparent conductive film may be provided on the surface of the transparent substrate 2B (the surface on the side of the electromagnetic wave generation source).

The transparent conductive film is made of transparent substrates 2A and 2B.
May be provided at two or more of the bonding surface and the surface.

The constituent materials of the transparent substrates 2A and 2B include:
Glass, polyester, polyethylene terephthalate (PET), polybutylene terephthalate, polymethyl methacrylate (PMMA), acrylic plate, polycarbonate (PC), polystyrene, triacetate film, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyethylene, ethylene Vinyl acetate copolymer, polyvinyl butyral, metal ion crosslinked ethylene-methacrylic acid copolymer, polyurethane, cellophane, and the like, preferably, glass, PET, PC, and PMMA.

The thickness of the transparent substrates 2A and 2B is appropriately determined according to the required characteristics (for example, strength and light weight) depending on the use of the obtained window material, but usually 0.1 to 10 mm.
Range.

The transparent substrates 2A and 2B are not necessarily made of the same material. For example, when the front side only needs to be scratch-resistant or durable, as in the case of a PDP front filter, the transparent side 2A, 2B may be used. Transparent substrate 2A having a thickness of 0.1 to 1
A glass plate of about 0 mm, and a transparent substrate 2B on the back side is made of PET film or PET having a thickness of about 1 μm to 10 mm.
A plate, an acrylic film or an acrylic plate, a polycarbonate film or a polycarbonate plate can also be used.

As the transparent conductive film 5, ITO (tin indium oxide), ZnO, ZnO doped with Al,
A thin film such as SnO ₂ can be formed. Also silver,
Even when a thin metal film such as copper is coated thinly, a heat ray reflective film that has visible light transmittance and reflects infrared light can also be used. The film thickness varies depending on the required electromagnetic wave shielding properties, light transmission properties, and heat insulation properties, but is usually about 10 to 5 μm for a metal oxide thin film and about 5 to 3000 degrees for a metal thin film. preferable.

In the electromagnetic wave shielding light transmitting window material of the present invention, the transparent substrate 2A on the front side is further subjected to a hard coat treatment with a silicon-based material or the like, or a light scattering material is kneaded into the hard coat layer. However, anti-glare processing may be performed. In addition, the transparent substrate 2B on the back side has
Functionality can be enhanced by applying a heat ray reflective coat of ITO, ZnO, silver or the like.

The conductive mesh interposed between the transparent substrates 2A and 2B is preferably a metal mesh and / or a metal-coated organic fiber having a wire diameter of 1 μm to 1 mm and an aperture ratio of 50 to 90%. In this conductive mesh, the wire diameter is 1
If it exceeds mm, the aperture ratio will decrease or the electromagnetic wave shielding property will decrease, making it impossible to achieve both. If it is less than 1 μm, the strength as a mesh decreases, and handling becomes extremely difficult. If the aperture ratio exceeds 90%, it is difficult to maintain the shape as a mesh, and if it is less than 50%, the light transmittance is low, and the amount of light from the display is reduced. More preferable wire diameter is 10 to 500 μm, and aperture ratio is 6
0 to 90%.

The aperture ratio of the conductive mesh means the ratio of the area occupied by the openings in the projected area of the conductive mesh.

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

In the present invention, the adhesive resin 4 for bonding the transparent substrates 2A and 2B via the conductive mesh 3 includes:
Ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene-ethyl (meth) acrylate copolymer, ethylene-methyl (meth) acrylate copolymer Copolymer, metal ion crosslinked ethylene- (meth) acrylic acid copolymer, partially saponified ethylene-vinyl acetate copolymer, carboxylated ethylene-vinyl acetate copolymer, ethylene- (meth) acryl-maleic anhydride copolymer, Ethylene-vinyl acetate-
An ethylene-based copolymer such as a (meth) acrylate copolymer is mentioned ("(meth) acryl" indicates "acryl or methacryl"). In addition, polyvinyl butyral (PVB) resin, epoxy resin, acrylic resin, phenol resin, silicone resin, polyester resin, urethane resin, etc. can also be used, but the most balanced in terms of performance and ethylene-vinyl acetate is easy to use. It is a copolymer (EVA). Further, PVB resins used in laminated glass for automobiles are also suitable in terms of impact resistance, penetration resistance, adhesiveness, transparency and the like.

The PVB resin contains 70 to 95% by weight of a polyvinyl acetal unit, 1 to 15% by weight of a polyvinyl acetate unit, and has an average degree of polymerization of 200 to 3,000, preferably 3,
It is preferably from 00 to 2500, and the PVB resin is used as a resin composition containing a plasticizer.

Examples of the plasticizer for the PVB resin composition include organic plasticizers such as monobasic acid esters and polybasic acid esters, and phosphoric acid plasticizers.

Examples of the monobasic acid ester include butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptanoic acid, n-octylic acid, 2-ethylhexylic acid, pelargonic acid (n-
Esters obtained by the reaction of an organic acid such as nonylic acid) and decylic acid with triethylene glycol, and more preferably triethylene-di-2-ethylbutyrate and triethylene glycol-di-2-ethylhexo. Ethates, triethylene glycol-di-capronate, triethylene glycol-di-n-octoate and the like. Note that an ester of the above organic acid with tetraethylene glycol or tripropylene glycol can also be used.

As the polybasic acid ester plasticizer, for example, an ester of an organic acid such as adipic acid, sebacic acid, azelaic acid and a linear or branched alcohol having 4 to 8 carbon atoms is preferable, and more preferably. , Dibutyl sebacate, dioctyl azelate, dibutyl carbitol adipate and the like.

Examples of the phosphoric acid plasticizer include tributoxyethyl phosphate, isodecylphenyl phosphate, triisopropyl phosphate and the like.

In the PVB resin composition, if the amount of the plasticizer is small, the film-forming property is reduced, and if the amount is large, the durability at the time of heat resistance is impaired. Therefore, the plasticizer is added in an amount of 5 to 100 parts by weight of the polyvinyl butyral resin. 50 parts by weight, preferably 10-4
0 parts by weight.

[0034] To the PVB resin composition, additives such as a stabilizer, an antioxidant and an ultraviolet absorber may be added in order to further prevent deterioration.

The electromagnetic wave shielding light transmitting window material of the present invention comprises:
A transparent conductive film 5 is formed in advance on necessary portions of the transparent substrates 2A and 2B, and two adhesive films formed into a sheet by mixing a predetermined amount of a crosslinking agent for heat or light curing with a resin such as EVA are used. After a conductive mesh is sandwiched between the adhesive films, the transparent film is interposed between the transparent substrates 2A and 2B, deaerated under reduced pressure and heating, and pre-compressed, and then the adhesive layer is cured by heating or light irradiation. It can be easily manufactured by integrating them.

The thickness of the adhesive layer formed by the conductive mesh 3 and the adhesive resin 4 varies depending on the use of the electromagnetic wave shielding light transmitting window material, but is usually 2 μm to 2 μm.
mm. Therefore, the adhesive film is formed to a thickness of 1 μm to 1 mm so as to obtain an adhesive layer having such a thickness.

Hereinafter, the adhesive layer according to the present invention will be described in more detail by exemplifying a case where EVA is used as the resin.

The EVA has a vinyl acetate content of 5 to 5
0% by weight, preferably 15-40% by weight is used. If the vinyl acetate content is less than 5% by weight, there is a problem in weather resistance and transparency, and if it exceeds 40% by weight, mechanical properties are remarkably deteriorated, film formation becomes difficult, and film mutual blocking occurs. .

When crosslinking by heating, an organic peroxide is suitable as the crosslinking agent, and is selected in consideration of sheet processing temperature, crosslinking temperature, storage stability and the like. Usable peroxides include, for example, 2,5-dimethylhexane-2,5-dihydroperoxide; 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexane-3; di-t-butyl peroxide; t-butylcumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; dicumyl peroxide Α, α'-
Bis (t-butylperoxyisopropyl) benzene;
n-butyl-4,4-bis (t-butylperoxy) valerate; 2,2-bis (t-butylperoxy) butane; 1,1-bis (t-butylperoxy) cyclohexane; 1,1- Bis (t-butylperoxy) -3,
3,5-trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide; tert-butylperoxyacetate; 2,5-dimethyl-2,5
-Bis (tert-butylperoxy) hexyne-3; 1,1
-Bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane; 1,1-bis (tert-butylperoxy) cyclohexane; methyl ethyl ketone peroxide; 2,5-dimethylhexyl-2,5-bisper Oxybenzoate; tertiary butyl hydroperoxide; p-menthane hydroperoxide; p-chlorobenzoyl peroxide; tertiary butyl peroxyisobutyrate; hydroxyheptyl peroxide; chlorohexanone peroxide. These peroxides are used alone or as a mixture of two or more, usually in a proportion of 10 parts by weight or less, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of EVA.

The organic peroxide is usually extruded to EVA,
It is kneaded by a roll mill or the like, but may be dissolved in an organic solvent, a plasticizer, a vinyl monomer or the like, and added to the EVA film by an impregnation method.

In order to improve the physical properties (mechanical strength, optical properties, adhesion, weather resistance, whitening resistance, crosslinking speed, etc.) of EVA, various acryloxy or methacryloxy and allyl group-containing compounds are added. be able to. As the compound used for this purpose, acrylic acid or methacrylic acid derivatives, for example, esters and amides thereof are the most common, and ester residues include methyl, ethyl, dodecyl, stearyl, lauryl and other alkyl groups, as well as cyclohexyl groups. , A tetrahydrofurfuryl group, an aminoethyl group, a 2-hydroxyethyl group, a 3-hydroxypropyl group, and a 3-chloro-2-hydroxypropyl group. Further, esters with polyfunctional alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol, trimethylolpropane, and pentaerythritol can also be used. As the amide, diacetone acrylamide is typical.

More specifically, polyfunctional esters such as acrylic or methacrylic esters such as trimethylolpropane, pentaerythritol and glycerin, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, and maleic Allyl group-containing compounds, such as diallyl acid, are listed. These may be used alone or as a mixture of two or more.
0.1 to 2 parts by weight, preferably 0.5 to 0 parts by weight
To 5 parts by weight.

When EVA is crosslinked by light, a photosensitizer is used in place of the above-mentioned peroxide in an amount of usually 10 parts by weight or less, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of EVA.

In this case, usable photosensitizers include:
For example, benzoin, benzophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, dibenzyl, 5-nitroacenaphthene, hexachlorocyclopentadiene, p-nitrodiphenyl, p-nitroaniline, 2,4,6-triene Nitroaniline, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-
1,9-benzanthrone and the like;
Species can be used alone or in combination of two or more.

In this case, a silane coupling agent is used in combination as an accelerator. As the silane coupling agent, vinyltriethoxysilane, vinyltris (β
-Methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Glycidoxypropyltriethoxysilane, β-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N
-Β (aminoethyl) -γ-aminopropyltrimethoxysilane and the like.

These silane coupling agents are usually EV
One or more kinds are mixed and used at a ratio of 0.001 to 10 parts by weight, preferably 0.001 to 5 parts by weight with respect to 100 parts by weight of A.

The EVA adhesive layer according to the present invention may further contain a small amount of an ultraviolet absorber, an infrared absorber, an antioxidant, and a paint processing aid, and may adjust the color of the filter itself. Colorants such as dyes and pigments, and fillers such as carbon black, hydrophobic silica, and calcium carbonate may be added in appropriate amounts.

Further, as means for improving the adhesiveness, means such as corona discharge treatment, low-temperature plasma treatment, electron beam irradiation, and ultraviolet light irradiation on the sheeted EVA adhesive film surface are also effective.

The EVA adhesive film according to the present invention comprises
It is manufactured by mixing VA and the above-mentioned additives, kneading them with an extruder, a roll, or the like, and then forming a sheet into a predetermined shape by a film forming method such as calender, roll, T-die extrusion, or inflation. During film formation, embossing is applied to prevent blocking and facilitate degassing during pressure bonding with a transparent substrate.

Such an electromagnetic wave shielding light transmitting window material of the present invention can be effectively used as a front filter of a PDP or a window material of a place where precision equipment is installed in a hospital or a laboratory.

[0051]

The present invention will be described more specifically below with reference to examples and comparative examples.

The adhesive films used in Examples and Comparative Examples were produced as follows. Production of Adhesive Film 100 parts by weight of ethylene-vinyl acetate copolymer (Ultracene 634 manufactured by Toyo Soda Co., Ltd .: vinyl acetate content: 26%, melt index: 4) was added to 100 parts by weight of 1,1-bis (t-butylperoxy) -3, 1 part by weight of 3,5-trimethylcyclohexane (Perhexa 3M manufactured by NOF Corporation), 0.1 part by weight of γ-methacryloxypropyltrimethoxysilane, 2 parts by weight of diallyl phthalate, and Sumisolve 130 (Sumitomo Chemical Industries, Ltd.) as an ultraviolet absorber And 0.5 parts by weight) were mixed with each other to prepare a double-sided embossed adhesive film having a thickness of 500 μm using a 40 mm extruder.

Examples 1 to 12, Comparative Examples 1 and 2 Table 1 shows the front transparent substrate 2A and the rear transparent substrate 2B.
The transparent conductive films shown in Tables 2 and 3 were formed on the portions shown in Tables 2 and 3 of these transparent substrates 2A and 2B (however, in Comparative Examples 1 and 2, there was no transparent conductive film). Between them, two adhesive films sandwiching a conductive mesh shown in Tables 2 and 3 are interposed, put in a rubber bag, degassed under vacuum, and heated at a temperature of 90 ° C. for 10 minutes. Pre-compression bonding. After that, put this pre-pressed body in the oven,
Heat treatment was performed at 150 ° C. for 15 minutes, followed by cross-linking and curing to integrate.

With respect to the obtained window material, 3
The electromagnetic wave shielding property, light transmittance, and the presence or absence of the moiré phenomenon at 0 MHz to 300 MHz were examined, and the results are shown in Tables 2 and 3.

Electromagnetic Wave Shielding Attenuation of the electric field was measured using an EMI shield measuring device (MA8602B) manufactured by Anritsu Corporation in accordance with the KEC method (Kansai Electronic Industry Promotion Center). Sample size is 9
It was 0 mm x 110 mm. Light transmittance (%) The average visible light transmittance between 380 nm and 780 nm was determined using a visible ultraviolet light spectrometer (U-4000) manufactured by Hitachi. Moire phenomenon was observed. The device was set on a display, and whether or not interference fringes were generated on the screen was visually observed.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

Tables 2 and 3 show that the present invention provides a good electromagnetic wave shielding light transmitting window material.

In the case of the comparative example having no transparent conductive film, a moire phenomenon occurs between the mesh and the display matrix. On the other hand, by combining the open mesh and the transparent conductive film as in the present invention, it was possible to produce a filter having no moire phenomenon, excellent electromagnetic wave shielding properties, and excellent light transmittance.

[0061]

As described in detail above, the electromagnetic wave shielding light transmitting window material of the present invention has good electromagnetic wave shielding and light transmitting properties and can reduce the moire phenomenon occurring between the display and the matrix. Has a function. Also, since the transparent substrate is firmly joined with a transparent adhesive,
The transparent substrate is not broken and scattered at the time of impact, has high safety, and is extremely useful industrially as an electromagnetic wave shielding filter for PDP.

[Brief description of the drawings]

FIGS. 1A to 1C are schematic sectional views showing an embodiment of an electromagnetic wave shielding light transmitting window material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A, 1B Electromagnetic wave shielding light transmission window material 2A, 2B Transparent substrate 3 Conductive mesh 4 Adhesive resin 5 Transparent conductive film

Claims (2)

[Claims] 1. An electromagnetic wave shielding light transmitting window material formed by bonding a conductive mesh between two transparent substrates with an adhesive resin interposed therebetween, wherein at least one of the two transparent substrates is transparent. An electromagnetic wave shielding light transmitting window material, wherein a transparent conductive film is formed on one or both surfaces of a substrate. 2. The electromagnetic wave shielding light transmitting window material according to claim 1, wherein the adhesive resin is an ethylene-vinyl acetate copolymer.