JPH11354978A - Production of translucent electromagnetic wave shield member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an electromagnetic wave shield member excellent in translucence and electromagnetic wave shielding properties through a simple method at a low cost. SOLUTION: A stripe-like or grid-like electromagnetic wave shield pattern 10 having line width of 5-80 μm, line interval of 200-300 μm and film thickness of 0.5-50 μm is formed by printing a conductive resin composition containing metal powder onto the surface of a transparent basic material 2 by intaglio offset printing using a blanket excellent in ink mold releasing properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a translucent electromagnetic wave shield capable of effectively shielding an electromagnetic wave emitted from a display unit of an electronic device such as a CRT and having an excellent translucency and an electromagnetic wave shielding effect. The present invention relates to a method for manufacturing a member.

[0002]

2. Description of the Related Art In recent years, various reports have been made on the effects of electromagnetic waves generated from electric equipment on the human body, and accordingly, techniques for shielding electromagnetic waves have been attracting attention in the field of office automation equipment such as personal computers. .

In order to shield electromagnetic waves, a method is generally used in which a housing of an electric device is made of a metal body, or a metal plate is attached to the housing. However, for example, CRT and PDP
In order to shield electromagnetic waves emitted from display screens such as those, it is required that the shielding effect (shielding effect) of the electromagnetic waves be excellent and the light transmitting property be excellent. Can not.

[0004]

Conventionally, for the purpose of shielding electromagnetic waves emitted from a display screen such as a CRT by covering the display screen, for example, (1) a metal filament having high conductivity is mixed. (2) A transparent base material in which fibers of a conductive material such as stainless steel and tungsten are embedded.
JP, JP-A-5-269912, JP-A-5-3
No. 27274) and (3) a transparent substrate having a metal or metal oxide deposited film formed on the surface thereof (Japanese Patent Laid-Open No. 1-278).
No. 80, Japanese Unexamined Patent Publication No. 5-323101).

[0005] However, when the mesh (1) is used, the display screen becomes dark, and the contrast and resolution decrease.
The transparent member of the above (2) has a problem that the production method is complicated and the cost is increased and the display screen is dark because the fibers are embedded therein.
Further, in the case of the above (3), if the deposited film is made thin enough to maintain sufficient translucency, the surface resistance of the film decreases,
Since the attenuation characteristics of electromagnetic waves are also reduced, it is not possible to achieve both light transmittance and an excellent shielding effect (shielding effect). If an indium-tin oxide film (ITO film) is used, the surface resistance of the film can be reduced while maintaining transparency.
The production cost of the membrane is high, which is extremely disadvantageous in terms of cost.

[0006] In addition to the above-mentioned examples, a member for covering a display screen such as a CRT or the like to shield electromagnetic waves may be made of an ink or paint mixed with highly conductive metal powder by screen printing to form a grid or stripe pattern. Transparent base material formed by printing as described in JP-A-62-57297 and JP-A-9-28
No. 3977), a network-like pattern made of a conductive paint is printed and formed on the surface of a transparent substrate by screen printing and baked in a vacuum (Japanese Patent Application Laid-Open No. 2-52499).
However, even if these members are used, it is not possible to achieve both a sufficient electromagnetic wave shielding effect and a sufficient translucency.

This is because it is necessary to consider the line width of the pattern, the interval (pitch) of the pattern, and the thickness of the pattern in order to achieve both the excellent electromagnetic wave shielding effect and the excellent translucency. It is considered that the above-mentioned publications do not sufficiently consider such points and the method for forming a pattern. That is, for example, in order to obtain sufficient translucency, it is preferable to make the line width of the pattern extremely thin and increase the interval between them, but in this case, the shielding effect becomes insufficient. In addition, it is difficult to form a pattern having a very small line width by a method such as screen printing, which causes problems such as variations in the line width of the pattern and a large number of locations where the pattern is interrupted (disconnected). on the other hand,
In order to enhance the shielding effect, it is preferable to increase the thickness of the pattern. However, in this case, the viewing angle of the electromagnetic wave shielding member becomes narrow, which causes a decrease in light transmission.

JP-A-3-35284 discloses that a film made of a conductive material is formed on the surface of a transparent plastic substrate by vapor deposition or the like and then patterned by chemical etching.
The publication describes that a geometric pattern made of a conductive material is provided on the surface of a transparent substrate by a chemical etching process.

According to the methods described in these publications, very fine patterns can be formed with high precision. However, since the photolithography method is used to form a fine pattern in the etching process, the manufacturing cost is extremely high, which is disadvantageous in cost.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to produce a light-transmitting electromagnetic wave shielding member excellent in both light-transmitting property and electromagnetic wave shielding effect by a simple method and at low cost. Is to provide a way.

[0011]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have applied an intaglio offset printing method using a blanket excellent in ink releasability to shield electromagnetic waves. By forming the pattern portion, it is possible to form a fine electromagnetic wave shield pattern with a simple method and at low cost, and (1) the line width, line interval and thickness of the pattern in the electromagnetic wave shield pattern portion are set to predetermined values. Or (2) setting the ratio of the area where the electromagnetic wave shield pattern is formed to the area where the electromagnetic wave shield pattern is not formed, and the line width and thickness of the pattern in the electromagnetic wave shield pattern to a predetermined value By finding a new fact that it is possible to obtain a translucent electromagnetic wave shielding member excellent in both translucency and electromagnetic wave shielding effect, Which resulted in the completion of the invention.

That is, a first method for producing a light-transmitting electromagnetic wave shielding member is a method in which a conductive resin composition containing metal powder is applied to a transparent substrate by an intaglio offset printing method using a blanket having excellent ink release properties. By printing on the surface of the pattern, a stripe or lattice pattern is formed, and the line width of the pattern is 5 to 80 μm and the line interval is 200 to 3
An electromagnetic wave shielding pattern portion having a thickness of 000 μm and a thickness of 0.5 to 50 μm is formed.

[0013] A second method for producing a light-transmitting electromagnetic wave shielding member is a method in which a conductive resin composition containing a metal powder is applied to a transparent substrate by an intaglio offset printing method using a blanket having excellent ink release properties. By printing on the surface of
The total area Ss of the electromagnetic wave shield pattern portion and the total area Sk of the region where the electromagnetic wave shield pattern portion is not formed on the surface of the transparent substrate are expressed by the following equation (1): 3 ≦ Sk / Ss ≦ 40 (1) The line width of the pattern that satisfies and forms the electromagnetic wave shield pattern portion is 5 to 80 μm, and the film thickness is 0.5 to 5 μm.
An electromagnetic wave shield pattern portion having a thickness of 0 μm is formed.

According to the first and second manufacturing methods of the present invention, since the extremely fine pattern constituting the electromagnetic wave shield pattern portion is formed by printing, the light-transmitting electromagnetic wave shield member can be formed simply and at low cost. Can be obtained, and productivity can be improved and cost can be reduced. Further, the translucent electromagnetic wave shielding member obtained by the production method of the present invention has excellent translucency and exhibits an excellent electromagnetic wave shielding effect.
Even if the display screen of the RT tube or the like is covered, electromagnetic waves can be highly shielded without impairing the visibility of the display screen.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

A translucent electromagnetic wave shielding member 1 according to the present invention, for example, as shown in FIG.
The electromagnetic wave shield pattern portion 10 made of a conductive resin composition containing metal powder is formed by printing.

The pattern shape of the electromagnetic wave shield pattern portion includes, for example, a stripe pattern 11 shown in FIG.
Examples include the grid-like patterns 12 and 13 shown in FIGS.

The pattern shape of the electromagnetic wave shield pattern portion may be a geometric pattern in addition to the above-mentioned stripe shape and lattice shape. That is, for example, a triangle such as an equilateral triangle, an isosceles triangle, or a right triangle; a square such as a square, a rectangle, a rhombus, a parallelogram, or a trapezoid; a (positive) hexagon;
(Positive) octagon, (positive) dodecagon, (positive) octagon, and other (positive) N-gons; electromagnetic wave shielding of geometric patterns obtained by repeating various graphic units such as circles, ellipses, and stars The pattern section 10 may be used. In such a geometric pattern, the graphic unit may be a combination of two or more types. In addition, from the viewpoint of smoothly removing static electricity from the electromagnetic wave shielding member, it is preferable that each figure unit in the geometric pattern is continuous. As a specific example of the pattern shape composed of a geometric pattern, for example, as shown in FIG. 5, a circular pattern (FIG. 5A), a diamond pattern (FIG. 5B), and a regular hexagonal pattern (FIG. 5C) And the like. Fig. 5 (a)-
In (c), the hatched portion indicates the electromagnetic wave shield pattern portion 10, and the non-hatched portion indicates the region 20 where no pattern portion is formed.

The line width Ws, the line interval Wk (the interval between adjacent pattern portions 10) and the film thickness Wt of the pattern constituting the electromagnetic wave shield pattern portion 10, the total area Ss of the pattern portion 10, and the pattern portion are formed. The ratio Sk / Ss to the total area Sk of the unexposed region 20 is such that the pattern portion 10 itself has a sufficient effect of shielding electromagnetic waves, and the pattern portion 10 itself has to be transparent to the electromagnetic wave shielding member. Set within a range that cannot be recognized by the naked eye.

In the case where the pattern has a rectangular lattice shape, there are two types of intervals Wk and Wk 'in the line interval Wk of the pattern. In this case, the line intervals Wk and Wk'
It suffices that k ′ be within a predetermined range described later. In the case where the pattern is a geometric pattern, the line width Ws refers to the width of one unit (that is, a constituent unit such as a triangle, a quadrangle, an N-sided polygon, a circle, an ellipse, etc.) constituting the geometric pattern. The line interval Wk refers to the distance between units, and the square root of the area of one unit (that is, the length of one side when one unit is simulated as a square) is determined from the distance at the center position between adjacent units. The value obtained by subtracting the square root is defined as the distance between the units.

In the present invention, the pattern shape of the electromagnetic wave shield pattern portion 10 is changed to a stripe pattern 11 shown in FIG. 1, a grid pattern 12 shown in FIGS.
When (13) is used, (I) the line width Ws of the pattern portion 10 is 5
８０80 μm, the line spacing Wk is 200-3000 μm,
And (II) the total area Ss of the pattern portion 10 and the total area Sk of the region 20 where the pattern portion 10 is not formed on the surface of the transparent base material so that the film thickness Wt is 0.5 to 50 μm. Ratio Sk / Ss satisfies the expression (1): 5 ≦ Sk / Ss ≦ 40, and the line width Ws of the pattern portion 10 is 5 to 80 μm.
m, the film thickness Wt is set to be 0.5 to 50 μm.

In the case (I), the pattern portion 10
Is difficult to form so that the line width Ws is less than 5 μm, and disconnection is likely to occur, leading to a decrease in the electromagnetic wave shielding effect. Conversely, when the line width Ws exceeds 80 μm, the pattern portion 10 becomes easily recognizable by eyes, leading to a decrease in light transmission. The line width Ws is preferably 10 to 6 in the above range.
It is preferably 0 μm, more preferably 15 to 50 μm.

The line interval Wk of the pattern portion 10 is 200 μm
When the value is less than, the pattern portion 10 is easily recognized visually, which leads to a decrease in light transmission. Conversely, the line spacing Wk is 3000 μ
If m exceeds m, the electromagnetic wave shielding effect will be reduced. The line spacing Wk is particularly in the range of 250 to 2500 μm.
Is more preferable, and more preferably 400 to 1500 μm.

When the thickness Wt of the pattern portion 10 is less than 0.5 μm, the effect of shielding electromagnetic waves is reduced. vice versa,
When the film thickness Wt exceeds 50 μm, the pattern portion 10 is easily visually recognized depending on the angle at which the electromagnetic wave shielding member is viewed, which leads to a reduction in the viewing angle and, consequently, a reduction in light transmission.
The film thickness Wt is particularly preferably from 1 to 30 μm, more preferably from 2 to 15 μm, even more preferably from 2 to 10 μm in the above range.

On the other hand, in the case of the above (II), the ratio Sk /
When Ss is less than 3, the light transmittance becomes insufficient. Conversely, the ratio S
If k / Ss exceeds 40, the effect of shielding electromagnetic waves becomes insufficient. The ratio Sk / Ss is particularly 5 to 20 μm in the above range.
m, more preferably 5 to 10 μm.

The problem when the film thickness Wt is out of the above range in the case (II) is the same as that in the case (I).

As the transparent substrate used in the present invention, a glass or a film having sufficient transparency to visible light is used. After the conductive resin composition is printed on the transparent substrate, a heating step is performed. Therefore, those having sufficient heat resistance are preferable. Specifically, soda lime glass,
Examples thereof include polycarbonate, polyether sulfone, polymethyl methacrylate (PMMA resin), polyether sulfone (PES resin), polyimide resin, and polyethylene terephthalate (PET resin).

The thickness of the transparent substrate is not particularly limited, but is preferably as thin as possible from the viewpoint of maintaining the translucency of the electromagnetic wave shielding member. That is, it is usually set in the range of 0.05 to 5 mm depending on the form (film shape or sheet shape) at the time of use and the required mechanical strength.

The metal powder used in the present invention includes, for example, powders of silver, copper, nickel, palladium, gold, aluminum, tungsten, chromium, titanium and the like, and these may be used alone or in combination of two or more. Used. In the present invention, in addition to the metal simple powder,
Copper powder or nickel powder whose surface is coated with silver can also be used.

Among the metal powders exemplified above, silver powder is particularly preferably used because oxides having high insulating properties are hardly generated. Although the nickel powder has a volume resistivity not smaller than that of the silver powder or the copper powder, it has a high oxidation resistance, and thus is suitable for producing an electromagnetic wave shield pattern portion in which the shielding effect has little change with time. Since the surface of the copper powder is easily oxidized, it is preferable to use a resin that generates a reducing gas when hardened.

From the viewpoint of increasing the conductivity of the electromagnetic wave shield pattern portion to further enhance the electromagnetic wave shielding effect, the higher the packing density of the metal powder in the conductive resin composition, the better. On the other hand, the conductivity of the electromagnetic wave shield pattern portion is not determined only by the volume resistivity of the metal powder itself to be used, but largely depends on the contact resistance between the metal powders in the pattern portion. For example, even if metal particles are densely filled inside the electromagnetic wave shielding pattern portion, if the contact resistance between the metal powders is large, the conductivity of the entire pattern becomes low.

Therefore, the metal powder used in the present invention is:
Among the metal powders exemplified above, it is preferable that the tap density, which indicates the weight per volume when the metal powder is filled to a certain volume, is 3.0 g / cm ³ or more. If the tap density is less than 3.0 g / cm ³ , the packing density becomes low and the gap between the metal powders becomes large, so that the number of contact points between the metal powders decreases, and as a result, the contact resistance may increase. The tap density of the metal powder is preferably at least 4.0 g / cm ³ even within the above range, and is preferably 6.0 g / cm ^3.
It is more preferably at least cm ³ .

The average particle size of the metal powder is not particularly limited, but is preferably set in the range of usually 3 to 15 μm in consideration of being uniformly mixed in the conductive resin composition. If the average particle size exceeds the above range, the number of contact points between the metal powders decreases, and the contact resistance may increase.
In addition, there is a possibility that the surface of the electromagnetic wave shield pattern becomes uneven. Conversely, if the average particle size is below the above range, it may be difficult to uniformly disperse the metal powder in the conductive resin composition. On the other hand, for the purpose of increasing the packing density of the metal powder, a metal powder having an average particle diameter in the above range and a metal powder having an average particle diameter of 0.1 to 3 μm having a small particle diameter of 100: 1 to 100: 50 are used. You may mix by weight ratio.

The shape of the metal powder may be any shape such as a sphere or a scale, but in consideration of increasing the contact surface between the metal powders (reducing the contact resistance), the scale is larger than the sphere. It is preferred to use ones in the form.

Specific examples of the metal powder usable in the present invention are shown below.

[Silver powder]-Trade name of Fukuda Metal Foil & Powder Co., Ltd. "Silcoat AgC
-A "(flaky, average particle diameter 4.0 μm, tap density 3.3 g / cm ³ ) ・ Sylcoat AgCD-D (flaky, average particle diameter 7.0 μm, tap density 3.5 g) manufactured by the company / Cm ³ ) ・ Sylcote AgCL (Lake, average particle size 8.0 μm, tap density 3.7 g / cm ³ ) ・ Mitsui Metal Mining Co., Ltd. product name “3200HD” Spherical, average particle size 4.2 μm, tap density 4.4 g / cm
³ ).

[Copper powder]-"SRC-CU2-", trade name of Fukuda Metal Foil & Powder Co., Ltd.
4 "(spherical, average particle diameter 3 μm, tap density 3.0 g /
cm ³ ) ・ SRC-CU4-8 (spherical, average particle diameter 6 μm, tap density 5.2 g / cm ³ ) ・ SRC-CU15 (spherical, average particle diameter 1)
0 μm, tap density 4.5 g / cm ³ ) ・ FCC-SP-77 (irregular shape, average particle diameter 10 μm, tap density 3.9 g / cm ³ ) ・ FCC-SP -88 "(irregular shape, average particle diameter 10 μm, tap density 3.9 g / cm ³ ) ・ FCC-SP-99 (irregular shape, average particle diameter 8 μm, tap density 4.1 g / cm ³⁾・ Mitsui Metal Mining Co., Ltd. product name “MFP-1400”
(Spherical, average particle diameter 7 μm, tap density 5.5 g / cm
³ ).

[0038] [nickel powder] brand name "2020" of Mitsui Mining & Smelting Co., Ltd. (spherical, average particle diameter 0.2 [mu] m, a tap density of 3.0 g / cm ^3), - the company under the trade name "2050" ( Spherical, average particle size 0.
6 μm, tap density 3.5 g / cm ³ ).

[Copper powder whose surface is coated with silver]-"4% silver coated SR" (trade name) of Fukuda Metal Foil & Powder Co., Ltd.
“C-CU2-4” (spherical, average particle diameter 3 μm, tap density 3.0 g / cm ³ ), “4% silver coated SRC-CU4-8” (spherical, average particle diameter 6 μm, tap density 5) .2g / c
m ³ ), "4% silver coated SRC-CU15" (spherical,
(Average particle diameter 10 μm, tap density 4.5 g / cm ³ ) ・ Mitsui Metal Mining Co., Ltd. trade name “Silver coated CU powder” (spherical, average particle diameter 7 μm, tap density 5.5 g /
cm ³ ).

[Palladium powder]-"MFP-4030" (trade name) of Mitsui Kinzoku Mining Co., Ltd.
(Spherical, average particle size 0.03 μm, tap density 0.6 g
/ Cm ³ ). - manufactured by the same company in "MFP-4100" (spherical, average particle diameter 0.4 .mu.m, a tap density of 2.9g / cm ^3).

The amount of the metal powder is determined according to the packing density of the metal powder and the conductivity required of the electromagnetic wave shielding pattern portion, and is not particularly limited, but is based on 100 parts by weight of the thermoplastic resin. And usually 400-1200
Parts by weight, preferably in the range of 600 to 1000 parts by weight. If the amount of the metal powder is less than 400 parts by weight, there is a possibility that the contact points between the metal powders become insufficient, and the volume specific resistance of the electromagnetic wave shield pattern portion increases.
Conversely, if the amount of the metal powder exceeds 1200 parts by weight,
The content of the resin with respect to the total amount of the conductive resin composition becomes too small, so that the force for binding the metal powder becomes small, and as a result, the volume resistivity of the electromagnetic wave shield pattern portion may become large. The amount of the metal powder is 120
If the amount exceeds 0 parts by weight, the strength of the electromagnetic wave shield pattern may be insufficient.

The resin used in the conductive resin composition of the present invention includes, for example, thermoplastic resins such as polyester resin, polyimide resin, polyethylene resin, polystyrene resin, acrylic resin, polyamide resin; phenol resin, epoxy resin, amino resin Any of the thermosetting resins can be used.

Above all, a reducing gas is generated during heating and curing to prevent oxidation of the metal powder, and the volume resistivity of the metal itself (for example, the silver volume resistivity is 1.62 × 10 ^−6).
(Ω · cm) is preferably used.

Examples of such a resin include a thermosetting resin which generates a reducing gas such as ammonia, hydrogen halide, or formaldehyde during curing, preferably formaldehyde. Examples of the thermosetting resin that generates formaldehyde include a phenol resin (especially a resole-type phenol resin having many methylol groups) and an amino resin (especially a melamine resin).

As a specific example of the resole type phenol resin, for example, a trade name “REGITOP P” of Gunei Chemical Industry Co., Ltd.
L2211 "and" PL4348 "manufactured by the same company. As a specific example of the melamine resin, there is, for example, a product name “Cymel 370” of Mitsui Cyanamid Co., Ltd.

The conductive resin composition is prepared into a paste by adding a solvent to the mixture of the resin and the metal powder in order to obtain a viscosity suitable for printing by the intaglio offset printing method.

As a solvent to be used, for example, a solvent having a boiling point of 150 ° C. or more is preferably used. When the boiling point of the solvent is lower than the above range, the solvent tends to dry during printing, and pinholes may be generated.

Specific examples of the solvent include alcohols such as hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, stearyl alcohol, seryl alcohol, cyclohexanol and terpineol; Alkyl ethers such as butyl ether (butyl cellosolve), ethylene glycol monophenyl ether, diethylene glycol, diethylene glycol monobutyl ether (butyl carbitol), cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, etc .; Is appropriately selected in consideration of

When a higher alcohol is used as a solvent, the drying property and fluidity of the ink may be reduced.
Butyl cellosolve, ethyl carbitol, butyl cellosolve acetate, butyl carbitol acetate and the like may be used in combination.

The amount of the solvent to be used is determined by the viscosity of the conductive resin composition, and usually 100 to 5 parts by weight based on 100 parts by weight of the resin in consideration of the amount of the metal powder to be added.
00 parts by weight, preferably 100 to 300 parts by weight. If the amount of the solvent used falls below the above range, the viscosity is 100 even when the addition amount of the metal powder is the minimum of 400 parts by weight.
It becomes 0P (poise) or more, and when printing on a transparent substrate, many pinholes occur. Conversely, if it exceeds the above range, the viscosity becomes 10 P or less even when the maximum amount of the metal powder used is 1000 parts by weight, and the adhesive strength to the transparent substrate is insufficient. As a result, the conductive resin composition is repelled from the transparent base material, and it becomes impossible to form an electromagnetic wave shield pattern portion with a good printed shape.

The viscosity of the conductive resin composition in the present invention is generally 10 to 1000 P, preferably 100 to 500 P.
It is preferable to adjust to P. If the viscosity is lower than the above range, the printed shape is deteriorated. On the other hand, when the viscosity is higher than the above range, many pinholes occur.

As described above, the light-transmitting electromagnetic wave shielding member of the present invention is formed by intaglio offset printing using a blanket excellent in ink releasability to form an electromagnetic wave shielding pattern portion on a transparent substrate in a predetermined pattern. It is manufactured by printing and then heat drying.

The intaglio offset printing method is excellent in that linearity of formed lines is good and extremely fine patterns can be printed with high precision. Further, by using a blanket having excellent ink release properties, a pattern having a uniform thickness can be formed even when the line width of the pattern is extremely small.

Examples of the intaglio used in the present invention include glasses such as soda lime glass, non-alkali glass, quartz glass, low alkali glass, and low expansion glass; fluororesins, polycarbonate resins, polyethersulfone resins, polymethacrylic resins, etc. Resin; stainless steel, copper,
A metal such as low expansion alloy invar is used. Among them, the use of soft glass such as soda lime glass,
This is preferable for reproducing a fine pattern with high accuracy.

The line width, line interval, and depth of the intaglio recess are appropriately set according to the shape of the electromagnetic wave shield pattern portion.

The blanket used in the present invention is not particularly limited as long as it has excellent ink releasability. For example, the surface is made of silicone rubber, fluororesin, fluororubber or a mixture thereof. Blanket. An index indicating the ink releasability of the blanket includes, for example, the surface energy of the blanket surface, and the value is preferably from 15 to 30 dyn / cm, more preferably from 18 to 25 dyn / cm.

The pattern of the conductive resin composition printed and formed on the transparent substrate is usually from 150 to 250 ° C. and from 10 to 90 ° C.
For 15 minutes to 60 minutes, preferably at 150 to 250 ° C., thereby obtaining the electromagnetic wave shielding member of the present invention.

[0058]

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

[Preparation of Conductive Resin Composition] Reference Example An ester of trimellitic anhydride and neopentyl glycol (weight average molecular weight Mw 20,000) manufactured by Sumitomo Rubber Industries, Ltd. was used as a polyester resin. Silver powder includes Fukuda Metal Foil & Powder Co., Ltd. product name “Silcoat Ag
CD "(supra).

A paste-like conductive resin composition was obtained by mixing 100 parts by weight of the polyester resin, 600 parts by weight of the silver powder and 10 parts by weight of toluene and kneading with a three-roll mill.

[Preparation of Transparent Electromagnetic Wave Shielding Member] A soda-lime glass plate having a thickness of 1 mm was used as a transparent substrate.

In the case where the electromagnetic wave shield pattern portion is formed by intaglio offset printing, an intaglio plate made of soda-lime glass in which the opening width and depth of the concave portion are set to predetermined values is used.

The blanket has a silicone rubber surface (additional RTM silicone rubber having a JIS A hardness of 40),
Surface ten-point average roughness 0.1 μm, surface energy 21d
yn / cm) or acrylonitrile-butadiene rubber (NBR, JI
Either an NBR blanket having an SA hardness of 40, a ten-point average roughness of the surface of 4 μm, and a surface energy of 37 dyn / cm) was used.

Examples 1 to 7 and Comparative Examples 1 to 6 After the conductive resin composition obtained in the above reference example was printed on the transparent substrate by intaglio offset printing using the silicone blanket and intaglio, By heating at 250 ° C. for 20 minutes using a hot plate, a translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern portion having a lattice pattern with a square lattice portion was obtained.

The line width Ws, line interval Wk, film thickness Wt, and Sk / Ss ratio of the patterns in each of the examples and comparative examples are as shown in Table 1.

[Evaluation of Physical Properties of Transparent Electromagnetic Shielding Member]
The following physical properties were evaluated for the translucent electromagnetic wave shielding members obtained in the above Examples and Comparative Examples.

(Electromagnetic Wave Shielding Property) Shield Material Evaluator of Completely Sealed Type (“TR17301” manufactured by Advantest Co., Ltd.)
A)), an electromagnetic wave having a frequency of 1 to 500 MHz was irradiated to evaluate the shielding property (shielding effect) of the electromagnetic wave. The larger the dB, the better the electromagnetic wave shielding property. The evaluation criteria are as follows. Good: Electromagnetic wave shielding effect was good at 40 dB or more. ×: Less than 40 dB, shielding of electromagnetic waves was insufficient.

(Transmittance) Using a spectroscopic microscope (“MCPD2000” manufactured by Otsuka Electronics Co., Ltd.), a wavelength of 400 to 700 n
The transmittance (%) of the m light (visible light) was measured, and the light transmittance was evaluated from the average value. The higher the transmittance, the better the light transmittance. ：: 70% or more, sufficient translucency. ×: Less than 70%, insufficient light transmission.

(Evaluation by visual observation) The translucent electromagnetic wave shielding member was visually observed and evaluated according to the following criteria. ：: The electromagnetic wave shield pattern could not be observed with the naked eye. ×: The electromagnetic wave shield pattern portion can be observed with the naked eye.

(Comparison of Manufacturing Costs) Assuming that the cost required for manufacturing the translucent electromagnetic wave shielding member by the intaglio offset printing method in Examples 1 to 7 and Comparative Examples 1 to 6 is 1, the manufacturing cost by the other manufacturing methods is reduced. The ratio was determined. Table 1 shows the above results.

[0071]

[Table 1] Comparative Example 7 A translucent electromagnetic wave shielding member was manufactured in the same manner as in Example 2 except that an NBR blanket was used in place of the silicone blanket, and the physical properties were evaluated.

Comparative Example 8 Instead of the intaglio offset printing method, the conductive resin obtained in the reference example was obtained by using a flat plate offset printing method using a waterless flat plate [Table name "TAN" manufactured by Toray Industries, Inc.] By printing the composition on a transparent substrate, a translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern portion having a line width Ws, a line interval Wk, and a film thickness Wt shown in Table 2 was manufactured.

Comparative Example 9 The screen printing method was used in place of the intaglio offset printing method, and the conductive resin composition obtained in the Reference Example was printed on a transparent substrate. Interval W
A light-transmitting electromagnetic wave shielding member having an electromagnetic wave shielding pattern portion having k and a film thickness Wt was manufactured.

Comparative Example 10 A 20 μm-thick silver thin film was deposited on the entire surface of a transparent substrate, and then a photoresist was formed on the entire surface of the silver thin film.

A photomask having a lattice pattern is provided on the photoresist, and etching is performed by a photolithography method, so that a translucent electromagnetic wave having an electromagnetic wave shield pattern portion having a line width Ws and a line interval Wk shown in Table 2 is obtained. A shield member was manufactured.

The evaluation results of the respective physical properties in the electromagnetic wave shield pattern portions of Comparative Examples 7 to 10 were determined based on the line width W of the pattern.
Table 2 shows the values of s, line spacing Wk, film thickness Wt, and Sk / Ss.

[0077]

[Table 2] * 1 and * 2 in Table 2 are as follows. * 1: Variations in film thickness were large, and there were many breaks in the pattern. * 2: Many disconnections in the pattern were observed.

As is clear from Tables 1 and 2, the line width Ws, the line interval Wk, and the film thickness Wt of the electromagnetic wave shield pattern portion are shown.
However, in Examples 1 to 6 satisfying the condition (I) or the condition (II), all of them have excellent electromagnetic wave shielding effect and translucency, and both can be compatible. The cost could be kept low.

On the other hand, in Comparative Example 1 in which the film thickness Wt of the electromagnetic wave shielding pattern portion is too small, Comparative Example 3 in which the line width Ws is too small, and Comparative Example 6 in which the line interval Wk is too wide, the electromagnetic wave shielding properties are all low. It was not enough. Comparative Example 2 in which the thickness Wt of the electromagnetic wave shield pattern portion was too large,
In Comparative Example 4 in which the line width Ws was too large and in Comparative Example 5 in which the line interval Wk was too narrow, the translucency was insufficient.
Particularly, in Comparative Examples 4 and 5, when the electromagnetic wave shielding member was actually used, it was dark and hard to see.
In this case, when viewed from an oblique direction, the pattern portion can be visually confirmed, causing a problem that unevenness in light transmission occurs.

In Comparative Example 7 using an NBR blanket with low ink release property, Comparative Example 8 using a flat plate offset printing method, and Comparative Example 9 using a screen printing method, the fine pattern was highly accurate. However, there was a problem in the shielding property of electromagnetic waves and visual evaluation.

Further, in Comparative Example 10 in which the electromagnetic wave shield pattern portion was formed by the photolithography method, although a fine pattern could be formed, there was a problem that the manufacturing cost was extremely high.

[0082]

As described in detail above, according to the present invention,
An electromagnetic wave shielding member having excellent translucency and excellent electromagnetic wave shielding effect can be manufactured by a simple method and at low cost.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing a translucent electromagnetic shield member, and FIG. 1 (b) is an enlarged cross-sectional view of AA part thereof.

FIG. 2 is a schematic diagram showing an example of a stripe pattern.

FIG. 3 is a schematic diagram illustrating an example of a lattice pattern.

FIG. 4 is a schematic view showing another example of a lattice pattern.

FIGS. 5A to 5C are schematic diagrams showing an example of a pattern formed of a geometric pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Translucent electromagnetic shielding member 2 Transparent base material 10 Electromagnetic shielding pattern part 11 Striped pattern 12 Lattice pattern 13 Lattice pattern Ws Line width Wk Line interval Wt Film thickness

Claims (3)

[Claims] An intaglio offset printing method using a blanket having excellent ink releasability, wherein a conductive resin composition containing a metal powder is printed on the surface of a transparent substrate to form a striped or grid pattern. The pattern has a line width of 5 to 80 μm and a line interval of 200 to 300
A method for manufacturing a light-transmitting electromagnetic wave shielding member, comprising forming an electromagnetic wave shielding pattern portion having a thickness of 0 μm and a thickness of 0.5 to 50 μm. 2. An intaglio offset printing method using a blanket having excellent ink releasability, by printing a conductive resin composition containing a metal powder on the surface of a transparent base material, so that the entire electromagnetic wave shield pattern portion is formed. The area Ss and the total area Sk of the region on the surface of the transparent substrate where the electromagnetic wave shield pattern portion is not formed satisfy Expression (1): 3 ≦ Sk / Ss ≦ 40 (1), and the electromagnetic wave shield The line width of the pattern constituting the pattern portion is 5 to 80 μm, and the film thickness is 0.5 to 5 μm.
A method for manufacturing a light-transmitting electromagnetic wave shielding member, comprising forming an electromagnetic wave shielding pattern portion having a thickness of 0 μm. 3. The method according to claim 1, wherein the surface of the blanket is made of silicone rubber.