JP2000269683A - Method for manufacturing light transmission electromagnetic wave shielding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively and easily manufacturing a light transmission electromagnetic wave shielding member with improved electromagnetic wave shield effect, and at the same time each improved characteristic of light transmission property, visibility, visual field angle, and contrast. SOLUTION: In this method for manufacturing a light transmission electromagnetic wave shielding member, a conductive resin composition containing metal power is filled into the recessed part of an intaglio, the intaglio and the surface of a transparent base 2 that is coated with a transparent elastomer on its surface are crimped, the conductive resin composition in the recessed part is transferred directly, thus forming an electromagnetic wave shielding pattern 10 on the transparent base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-transmitting electromagnetic wave shielding member capable of effectively shielding electromagnetic waves emitted from a display portion of an electronic device such as a CRT (CRT) and a PDP (plasma display panel). It relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, various reports have been made on the effects of electromagnetic waves radiated from electric devices on the human body.
Along with this, there is increasing interest in techniques for shielding electromagnetic waves radiated from a display screen such as a CRT. Conventionally,
In order to shield electromagnetic waves radiated from a display screen, an electromagnetic wave shielding member having a pattern made of a metal such as a copper foil formed on a surface of a transparent base material such as a transparent film is used. This electromagnetic wave shield member has a shield (shield) for electromagnetic waves.
In addition to being highly effective, it is required to have excellent translucency (transparency) and visibility, and to have a wide viewing angle. In particular, an electromagnetic wave shielding member for a PDP which is attracting attention as a next-generation image display device. Since electromagnetic waves emitted from a display screen of a PDP are stronger than a CRT or the like, more excellent electromagnetic wave shielding characteristics are required.

As a standard for the electromagnetic wave shielding effect, the Swedish MPRII standard is known as the strictest standard in the world, and is becoming a practical standard. In order to satisfy this standard, it is necessary to sufficiently cut electromagnetic waves in an extremely wide frequency range of 1 to 1000 MHz.

[0004]

The electromagnetic wave shielding effect,
Japanese Patent Application Laid-Open No. H10-163 discloses a method for manufacturing an electromagnetic wave shielding member that sufficiently satisfies various characteristics such as translucency, visibility, and viewing angle.
No. 673 and JP-A-5-16281 disclose that a copper foil layer is formed on the surface of a transparent substrate by electroless plating, a resist pattern is formed by a photolithographic method, and then the copper foil layer is patterned by etching. A method for doing so is disclosed. If a pattern is formed by the etching process in this manner, a very fine pattern can be formed with high accuracy. However, since most of the thin copper layer formed by plating is removed by etching, there is a problem that the manufacturing cost of the electromagnetic wave shielding member increases, such as waste of copper material and cost of waste liquid treatment. is there.

In particular, since PDPs are mainly developed for large screens, the size of the electromagnetic wave shielding member is also required to be increased. In this case, an exposure apparatus for forming a resist pattern in a photolithography method, an etching apparatus for etching, and the like. It is necessary to increase the size of the device and the like, and costs are increased in terms of capital investment. On the other hand, Japanese Patent Publication No. 2-48159 discloses that an ultraviolet-curable epoxy acrylate resin mixed with a metal powder is printed on a light-transmitting film to obtain a light-transmitting electromagnetic wave shielding member. According to such a method, the formation and etching of the copper coating layer by the above-described electroless copper plating or the like are not required, so that the production is simple,
There is no need to worry about copper waste liquid treatment. In addition, the amount of metal used, such as copper, is sufficient for the pattern formation, so that manufacturing costs can be reduced.

However, the above publication does not disclose a specific printing method. When an electromagnetic wave shielding pattern is formed by a conventional printing method, it is generally necessary to achieve both a sufficient electromagnetic wave shielding effect and translucency. At present, it has not been put to practical use because it is not possible. That is, in order to obtain good translucency and an excellent viewing angle, the line width of the pattern should be extremely small, the interval between them should be large, and the film thickness of the pattern should be small,
It has been difficult to form such a fine and thin pattern by a conventional printing method. For example, in the screen printing method, since the screen plate is stretched at the time of printing, the mesh expands and contracts, and a variation of about ± 20 μm occurs in a printing dimension and a printing position. Further, when a pattern having a line width of 50 μm or less is printed by a conventional screen printing method or a gravure printing method, variations in the pattern line width and disconnection occur, and the electromagnetic wave shielding effect and visibility are reduced.

Further, when the amount of the metal powder is increased in order to enhance the electromagnetic wave shielding effect, there arises a problem that the thickness of the pattern is further increased and the resin paste becomes unsuitable for printing. Furthermore, even if the amount of the metal powder is increased in a range suitable for printing, a pattern having sufficient conductivity could not be formed. Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a low-cost light-transmitting electromagnetic wave shielding member having an excellent electromagnetic wave shielding effect and also having excellent characteristics of light transmission, visibility, viewing angle and contrast. It is an object of the present invention to provide a manufacturing method which can be manufactured easily and easily.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, it has been found that if a predetermined treatment is applied to the surface of a transparent substrate in advance, a fine pattern can be reproduced. A completely new fact that it is possible to form a fine and high-precision electromagnetic wave shielding pattern by adopting intaglio printing method with excellent performance and printing by direct printing which is simpler than commonly used offset printing And completed the present invention.

That is, according to the method of manufacturing a light-transmitting electromagnetic wave shielding member of the present invention, after a conductive resin composition containing a metal powder is filled in a concave portion of an intaglio plate, the intaglio plate and a transparent elastomer coating are applied to the surface. The electromagnetic wave shield pattern is formed on the transparent substrate by pressing the applied surface of the transparent substrate and directly transferring the conductive resin composition in the concave portion.

According to the manufacturing method of the present invention, it is possible to obtain an electromagnetic wave shielding member having an excellent shielding effect in an extremely wide range where the frequency of electromagnetic waves is 1 to 1000 MHz, and to form a fine and highly accurate print pattern. As a result, it is possible to obtain a light-transmitting electromagnetic wave shielding member having excellent characteristics of light-transmitting property, visibility, viewing angle, and contrast. Further, by adopting the printing method, there can be obtained an advantage that the member can be easily manufactured at low cost.

In the method for manufacturing a light-transmitting electromagnetic wave shielding member according to the present invention, the electromagnetic wave shielding pattern is a stripe, a lattice, or a geometric pattern, and the line width Ws of the electromagnetic wave shielding pattern is 5 to 40 μm. The total area Ss of the electromagnetic wave shield pattern having a thickness Wt of 0.5 to 50 μm and the total area Sk of a region where the electromagnetic wave shield pattern is not formed is expressed by the following equation (1): 1 ≦ Sk / Ss ≦ 9 Preferably, it satisfies.

The line width Ws and the ratio S of the electromagnetic wave shield pattern
When k / Ss and film thickness Wt satisfy the above ranges,
The shielding performance of the electromagnetic wave shielding member can be further improved, and the light transmittance, visibility, and viewing angle can be further improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As described above, the method for manufacturing a translucent electromagnetic wave shielding member of the present invention involves printing a conductive resin composition on the surface of a transparent substrate to form a printed pattern corresponding to the conductive shield pattern. (1) The intaglio direct printing printing method is adopted as the printing method, and (2) a transparent elastomer coating is applied to the surface of the transparent substrate in advance to increase the ink receptivity, and the surface is given elasticity. It is characterized by keeping.

[Printing Method of Conductive Resin Composition] In the present invention, a printing method for printing a conductive resin composition includes a line having good linearity and an extremely fine pattern having high precision. The intaglio printing method which can reproduce the print by the method is used. Generally, in the intaglio printing method, an intaglio offset printing method is used in which ink is transferred from the intaglio to a printing medium via a blanket. According to this intaglio offset printing method, a pattern can be formed with a uniform thickness and high printing precision even when the line width of the pattern is extremely thin, less than 50 μm.

On the other hand, in the present invention, the elasticity of the transparent base material is enhanced by previously applying a transparent elastomer coating to the surface of the transparent base material, and as a result, ink receptivity is increased. Therefore, without using an elastic blanket, the conductive resin composition is directly transferred from the hard intaglio to the transparent substrate, by so-called direct printing, the same or better as the intaglio offset printing method A pattern can be formed with high printing accuracy.

By employing the intaglio direct printing, the step of temporarily transferring the conductive resin composition to a blanket can be omitted, so that the structure of the printing machine can be made extremely simple and the printing time can be reduced. And thus productivity can be improved. Also,
There is no need to consider the deterioration of the blanket due to continuous printing, and stable production can be performed.

Furthermore, since the resin composition is cut off only once when the conductive resin composition is transferred from the intaglio to the transparent substrate, a sufficient film thickness can be obtained by one printing. Pattern can be formed, thereby improving productivity and reducing manufacturing costs. Further, it is possible to form a pattern in which the shapes of lines and edges are extremely good and the printing accuracy is extremely high.

Assuming that the production cost when the method of printing the conductive resin composition by the intaglio direct printing method is 1 for forming the conductive shield pattern, the intaglio offset printing method and the lithographic offset printing method are used. Cost is 2-3
The cost when using the photolithography method is 5 to 10. (Intaglio) Intaglio used in the present invention includes, for example, glass such as soda lime glass, non-alkali glass, quartz glass, low alkali glass, and low expansion glass; fluororesin, polycarbonate resin, polyethersulfone resin, polymethacrylic resin, etc. Resin; metals such as stainless steel, copper, and low expansion alloy invar are used. Among them,
It is preferable to use a soft glass such as soda lime glass in order to reproduce a fine pattern with high accuracy. In addition, the intaglio is not limited to a flat one.For example, if the intaglio is on a cylindrical or curved surface, as described later, printing is performed by rolling the intaglio on a transparent substrate when forming a print pattern. And has the advantage of enabling continuous processing of the printing process.

The surface of the intaglio printing plate is required to be extremely flat in order to prevent the remaining of the ink during doctoring from causing stains on the non-image area (ground stains). In order to produce an intaglio with excellent surface flatness at the lowest cost, it is preferable to produce an intaglio by etching using the glass exemplified above. The line width and the line interval of the intaglio recess are appropriately set according to the shape of the electromagnetic wave shield pattern portion. Further, the depth of the intaglio concave portion is appropriately set according to the shape of the electromagnetic wave shield pattern portion, but it is usually appropriate to set it to about 1 to 50 μm.
When the ink transferability on the surface of the transparent base material is good, about half of the ink in the concave part transfers from the intaglio concave part to the transparent base material. May be set in consideration of.

(Transparent Substrate) The transparent substrate used in the present invention has excellent translucency to visible light and a conductive resin composition printed on the transparent substrate. A material having a sufficient heat resistance is preferable because a heating step is performed later. Further, it is preferable that the material has flexibility so that continuous processing can be performed by winding the film into a roll at the time of manufacturing.

Specifically, as the transparent substrate, polyesters such as polyethylene terephthalate (PET, refractive index n = 1.575); polyethylene (n = 1.51), polypropylene (n = 1.49), polystyrene (N =
Polyolefins such as 1.59); polyvinyl chloride (P
VC, n = 1.545), polyvinylidene chloride (PVD)
Vinyls such as C, n = 1.62); polyether sulfone; polymethyl methacrylate (PMMA resin, n = 1.
Acrylic resins such as 49); polyamide resins, polycarbonate resins (PC, n = 1.59), polyimide resins and the like. Above all, a PET film having very good visible light transmittance and being inexpensive is preferably used.

The transparent substrate is not limited to those described above, and various types of conventionally known glass substrates or resin substrates can be used as long as they are transparent. The thickness of the transparent substrate is not particularly limited, but is preferably thinner from the viewpoint of maintaining the translucency of the electromagnetic wave shielding member, depending on the form (film-like or sheet-like) in use and the required mechanical strength. Usually, it may be appropriately set in the range of 0.05 to 5 mm.

(Transparent Elastomer) The transparent elastomer used as a coating agent on the surface of the transparent substrate has a good affinity for both the surface of the transparent substrate and the conductive resin composition, and is shielded from electromagnetic waves. Any material may be used as long as it has sufficient transparency so as not to hinder the light transmittance of the member. Among them, from the viewpoint of maintaining the light transmittance of the electromagnetic wave shielding member, the refractive index n with the transparent base material is preferred. Is preferably as small as possible.

The refractive index n between the transparent substrate and the above elastomer
Is preferably 0.15 or less. Examples of the elastomer usable in the present invention include natural rubber (refractive index n = 1.52, Δn = 0.555), butadiene rubber (n = 1.50, Δn = 0.0075), polyvinyl chloride (n = 1.55, Δn = 0.025), chloroprene rubber, nitrile rubber and the like. In the above example,
Δn shown in parentheses is a polyethylene terephthalate (PET) film (n = 1.5) suitable as a transparent substrate.
75).

The additive to be added to the above elastomer has a refractive index similar to that of the elastomer,
Preferably, it can be uniformly dispersed in the elastomer. For example, when natural rubber is used as the elastomer, a very transparent coating can be formed by adding magnesium carbonate, which has a very close refractive index and can be dispersed uniformly.

The thickness of the coating made of the transparent elastomer is appropriately set according to the degree of deformation of the surface of the transparent substrate when the conductive resin composition is printed, and the transparency of the substrate. But generally 1 to 500 μm, especially 5
It is preferable to set the thickness in the range of 100 μm to 100 μm. If the coating is hard, the effect of imparting elasticity to the surface of the transparent substrate cannot be obtained, and if the coating is too soft, the amount of deformation during printing of the conductive resin composition increases, and high-precision printing is performed. You will not be able to do it. Therefore, the hardness of the coating is 1 to 80 degrees in JIS-A hardness, especially 10 to 80 degrees.
It is preferable to set the angle in the range of -70 degrees.

The above-mentioned coating may be applied with the above-mentioned elastomer (or a solution obtained by dissolving the above-mentioned elastomer in a suitable solvent) on the surface of a transparent substrate, cured, and then vulcanized as required. Vulcanization conditions may be appropriately set according to a conventional method, depending on the type of the elastomer. (Conductive resin composition) In the present invention, as the conductive resin composition which is printed on a transparent base material and constitutes an electromagnetic wave shielding pattern, at least a metal powder for imparting conductivity to a resin component is used. What is blended is used.

(I) Resin component The resin component in the conductive resin composition is, for example, a thermoplastic resin such as a polyester resin, a polyvinyl butyral resin, an ethyl cellulose resin, a polyethylene resin, a polystyrene resin, and a polyamide resin; (meth) acrylic resin UV-curable resins such as polyester-melamine resin, melamine resin, epoxy-melamine resin, phenol resin, epoxy resin, amino resin, polyimide resin,
Any of thermosetting resins such as (meth) acrylic resin can be used.

Among them, a resin that generates a reducing gas upon heating and curing is preferable because it can prevent oxidation of the metal powder and prevent the volume resistivity of the metal powder from decreasing. is there. Examples of such a resin include a thermosetting resin that 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).

(Ii) Metal Powder In the present invention, the metal powder to be mixed with the conductive resin composition includes, for example, silver, copper, nickel, palladium,
Powders of gold, aluminum, tungsten, chromium, titanium and the like can be mentioned, and these can be used alone or in combination of two or more. In addition, in the present invention, in addition to the powder of the simple metal, a powder obtained by coating the surface of a copper powder or a nickel powder with silver can be used.

Among the metal powders exemplified above, silver powder is particularly preferably used because it is difficult to form an oxide having a high insulating property and the volume resistivity is low. Although nickel powder has a volume resistivity not as small as silver powder or copper powder, it has high oxidation resistance, and thus is suitable for producing an electromagnetic wave shield pattern in which the shielding effect has little change with time. Copper powder is apt to be oxidized on the surface, and therefore is preferably used together with a resin that generates a reducing gas when cured.

The higher the packing density of the metal powder in the conductive resin composition, the better the conductivity of the electromagnetic wave shielding pattern and the higher the electromagnetic wave shielding effect. However, if the packing density is too high, the conductivity tends to worsen. In general, the conductivity is
It is best when the filling ratio of the metal powder is around 80%.

The conductivity of the electromagnetic wave shield pattern is not determined only by the volume resistivity of the metal powder used itself, but is greatly influenced by the contact resistance between the metal powders inside the pattern. For example, even if metal particles are densely filled in the electromagnetic shield pattern, if the contact resistance between the metal powders is large, the conductivity of the entire pattern may be reduced.

Although the average particle size of the metal powder is not particularly limited, it is usually preferably set in the range of 1 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 small particle having an average particle diameter of 0.01 to 3 μm have a particle diameter of 100: 1 to 100: 50. You may mix by weight ratio.

The shape of the metal powder may be any shape such as a sphere or a scale. However, in consideration of increasing the contact surface between the metal powders (reducing the contact resistance), the shape of the metal powder is larger than that of the sphere. It is preferred to use ones in the form. The blending amount of the metal powder in the conductive resin composition is set according to the packing density of the metal powder and the conductivity required for the electromagnetic wave shielding pattern, and is not particularly limited, but is usually limited. The content ratio in the conductive resin composition is 60 to 9;
It is set to be in the range of 5% by weight, preferably 70 to 90% by weight. If the content ratio of the metal powder is below the above range, the contact points between the metal powders become insufficient, and the volume resistivity of the electromagnetic wave shielding pattern may increase.
Conversely, when the content ratio exceeds the above range, the content of the resin with respect to the total amount of the conductive resin composition becomes too small, and the force for bonding the metal powder becomes small. As a result, the volume resistivity of the electromagnetic wave shielding pattern becomes small. There is me that becomes larger. Further, when the content ratio of the metal powder exceeds the above range,
The printability of the conductive resin composition may be reduced, or the strength of the electromagnetic wave shield pattern may be insufficient.

(Iii) Other Components 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 an intaglio offset printing method or the like. Is done. As the 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 usable solvents include hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, stearyl alcohol,
Alcohols such as seryl alcohol, cyclohexanol, and terpineol; ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monophenyl ether, diethylene glycol, diethylene glycol monobutyl ether (butyl carbitol),
Cellosolve acetate, butyl cellosolve acetate,
Examples thereof include alkyl ethers such as carbitol acetate and butyl carbitol acetate, which may be appropriately selected in consideration of printability and workability.

When a higher alcohol is used as a solvent, there is a possibility that the drying property and the fluidity of the conductive resin composition may be reduced. Therefore, butyl carbitol, butyl cellosolve, ethyl carbitol, which have better drying property than these, may be used. 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 is usually 100 to 500 parts by weight, preferably 100 to 500 parts by weight, per 100 parts by weight of the resin component, in consideration of the amount of the metal powder added. 3
It is preferably 00 parts by weight. When the amount of the solvent used falls below the above range, the viscosity becomes 1000 P (poise) or more even when the addition amount of the metal powder is the minimum of 400 parts by weight, and pinholes frequently occur when printing on a transparent substrate. I will. Conversely, if the ratio exceeds the above range, the amount of the metal powder used is the maximum of 1
Even if the amount is 000 parts by weight, the viscosity becomes 10 P or less, 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 shielding pattern 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. It is preferable that the conductive resin composition of the present invention further contains a black pigment in addition to the resin component and the metal powder. The black pigment blackens the layer formed by printing the conductive resin composition, prevents reflection from external light, and contributes to improving the contrast of the display screen.

Examples of such black pigments include various conventionally known carbon blacks such as acetylene black. Further, the content ratio of the black pigment in the conductive resin composition is 0.5 to 5 in the conductive resin composition.
It is set to be in the range of 0% by weight. If the content of the black pigment is less than the above range, the contrast may not be improved. Conversely, if the ratio exceeds the above range, the conductivity of the electromagnetic wave shielding pattern may be reduced, and the electromagnetic wave shielding effect may be reduced.

In addition, if agglomeration or poor dispersion of the metal powder or black pigment occurs in the conductive resin composition, a short circuit may occur between the internal electrodes. It can also be blended. Various surfactants can be used as the dispersant. Among them, a polymer surfactant is preferably used from the viewpoint of stabilizing the conductive resin composition.

The conductive resin composition used in the present invention comprises:
In addition to the above components, if necessary, auxiliary agents such as a plasticizer, an antistatic agent, an antifoaming agent, an antioxidant, a lubricant, and a curing agent are appropriately compounded, and a three-roller, a kneader or the like mixer is used. It is prepared by kneading and dispersing. Further, in order to further improve the dispersibility of the metal powder, the metal powder may be sufficiently mixed in advance with a planetary mixer or the like before kneading with three rolls or the like.

(Method of Forming Print Pattern) In the present invention, as a method of transferring the conductive resin composition containing the metal powder to the surface of the transparent substrate, (I) using a flat intaglio,
Either a method in which the transparent substrate wound around a cylindrical cylinder is rolled while being pressed against the intaglio plate, or (II) a method in which the cylindrical intaglio plate is used to roll while pressing the intaglio plate on a flat transparent substrate. It may be.

The pressure at the time of pressure contact is an important factor that affects printing accuracy.
kg / cm ^2, especially preferably set in the range of 2 to 10 kg / cm ^2. If the pressure exceeds the above range, the coating on the transparent substrate or the deformation of the transparent substrate or the intaglio itself becomes too large, and the printing accuracy may be impaired. Conversely, when the pressure is lower than the above range, the transfer of the conductive resin composition from the intaglio to the transparent substrate may be insufficient.

[Cutting Treatment of Print Pattern] The pattern of the conductive resin composition printed and formed on the transparent substrate is usually 8
0-250 ° C for 10-90 minutes, preferably 100-1
It is cured by heating and drying at 50 ° C. for 15 to 60 minutes. The heating conditions may be appropriately adjusted according to the curing temperature of the conductive resin composition and the heat resistant temperature of the transparent substrate.

The heating may be performed in a clean oven or the like. [One Embodiment of Translucent Electromagnetic Wave Shield Member] As one embodiment of the translucent electromagnetic wave shield member 1 obtained by the manufacturing method of the present invention, for example, as shown in FIG. One in which the shield pattern 10 is formed is exemplified.

(Shape of Electromagnetic Wave Shield Pattern) Examples of the shape of the electromagnetic wave shield pattern include a stripe pattern 11 shown in FIG. 2 and lattice patterns 12 and 13 shown in FIGS. The shape of the electromagnetic wave shield pattern may be a geometric pattern other than the above-mentioned stripe shape and lattice shape. That is, for example, a triangle such as an equilateral triangle, an isosceles triangle, and a right triangle; a square such as a square, a rectangle, a diamond, a parallelogram, and a trapezoid;
(Regular) hexagon, (Regular) octagon, (Regular) dodecagon, (Regular)
A (positive) N-polygon such as an icosagon; a geometric pattern obtained by repeating various graphic units such as a circle, an ellipse, and a star may be used as the electromagnetic wave shielding pattern. 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.

In FIGS. 2 to 4 and FIGS. 5 (a) to 5 (c), the hatched portions indicate the electromagnetic wave shield patterns 10, and the unhatched portions indicate the regions where the electromagnetic wave shield patterns are not formed. 20 is shown.
Line width Ws and line spacing Wk of the electromagnetic wave shield pattern 10
(Interval between adjacent patterns 10) and film thickness Wt;
The ratio Sk / Ss of the total area Ss of the electromagnetic wave shield pattern 10 to the total area Sk of the region 20 where the shield pattern is not formed is within a range in which the electromagnetic wave shielding effect can be sufficient. In order to ensure the translucency of the electromagnetic wave shielding member, the shielding pattern 10
It is set within a range that cannot be recognized by the naked eye.

In the case where the electromagnetic wave shield pattern has a rectangular lattice shape (FIG. 3), there are two types of line intervals Wk of the shield pattern, Wk and Wk '. It is sufficient that Wk 'is within a predetermined range described later. In the case where the electromagnetic wave shield 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-gon, 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 calculated 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.

(Line width Ws, film thickness Wt and ratio Ss / Sk
In the translucent electromagnetic wave shielding member of the present invention, the total area Ss of the area where the electromagnetic wave shield pattern is formed on the surface of the transparent base material and the total area Sk of the area where the shield pattern is not formed Ratio Ss / S
k is 1 or more and 9 or less, and the line width Ws of the shield pattern is 5 to 40 μm and the film thickness Wt is 0.5 to 50 μm.
It is preferably in the range of m.

Japanese Patent Application Laid-Open No. 10-156320 discloses that an electromagnetic wave shielding member has a line width of 5 to 80 μm and a line interval of 20.
There is a description that 0 to 3000 μm and a film thickness of 0.5 to 50 μm are preferable for obtaining a good shielding effect and transparency. However, as is clear from the results of Comparative Example 1 described later, 1 to 5 in the above range.
Although a good shielding effect can be obtained at 00 MHz, the shielding effect becomes insufficient in a high frequency region of 1000 MHz.

When the ratio Sk / Ss is less than 1, the light transmittance may be insufficient. Conversely, if the ratio Sk / Ss exceeds 9, the electromagnetic wave shielding effect may be insufficient. The ratio Sk / Ss is particularly preferably from 1 to 5 and more preferably from 1 to 3 in the above range. It is difficult to form the electromagnetic wave shield pattern so that the line width Ws is less than 5 μm, and disconnection easily occurs.
There is a possibility that the electromagnetic wave shielding effect is reduced and defective products are generated. Conversely, if the line width Ws exceeds 40 μm, the electromagnetic wave shield pattern is easily recognized visually, which may lead to a decrease in light transmission. The line width Ws is particularly preferably 5 to 25 μm in the above range, and is preferably 5 to 20 μm.
More preferably, it is μm.

When the thickness Wt of the electromagnetic wave shield pattern is 0.
When the thickness is less than 5 μm, disconnection of the pattern is likely to occur, and the conductivity is also reduced, which may lead to a reduction in the electromagnetic wave shielding effect. Conversely, when the film thickness Wt exceeds 50 μm, the electromagnetic wave shield pattern is easily recognized depending on the angle at which the shield member is viewed, which may lead to a decrease in visibility and a viewing angle, and eventually a decrease in light transmission. The film thickness Wt is particularly preferably 1 to 30 μm in the above range.

Aperture ratio (%) of translucent electromagnetic wave shielding member
Is determined from the line width Ws and the line interval Wk of the electromagnetic wave shield pattern by the following equation. Opening ratio = [Wk / (Wk + Ws)] ² × 100 Further, the opening ratio (%) has a relationship shown in the following equation with the ratio Sk / Ss. Sk / Ss = Aperture ratio / (100−Aperture ratio) In the translucent electromagnetic wave shielding member of the present invention, the aperture ratio is not particularly limited, and is determined according to the above-described ratio Sk / Ss and the like. Due to the balance between the translucency and the electromagnetic wave shielding property, it is usually 50 to 90%, preferably 60 to 90%.
It is set to be in the range of 80%. When the aperture ratio is less than the above range, the electromagnetic wave shielding effect is improved, but the light transmittance may be insufficient. Conversely, if it exceeds the above range, the electromagnetic wave shielding effect may be insufficient. In the case of a shield member for a PDP, since an excellent electromagnetic wave shielding property is required, the aperture ratio is particularly preferably 60% or more in the above range.

(Use of Transparent Electromagnetic Wave Shield Member) The translucent electromagnetic wave shield member of the present invention may be, for example, a CRT or PD.
By being installed on the front of the display screen of a display such as P, it is used for shielding electromagnetic waves radiated from the display screen, and a transparent adhesive layer is formed on the surface of the translucent electromagnetic wave shielding member, and this adhesive layer is formed. By bonding a display panel or a transparent base material of the display to the display panel, it can be used as an electromagnetic wave shielding panel integrated with the display.

[0056]

The present invention will be described below with reference to examples and comparative examples. [Production of translucent electromagnetic wave shielding member] As the conductive paste, 80 parts by weight of a polyester resin [manufactured by Sumitomo Rubber Industries, Ltd., ester of trimellitic anhydride and neopentyl glycol, weight average molecular weight Mw = 20,000] 80 parts by weight, melamine Resin [Sumimar M- manufactured by Sumitomo Chemical Co., Ltd.]
100C "], 20 parts by weight, 5 parts by weight of carbon black (average particle size: 20 nm), and 800 parts by weight of flaky silver powder [average particle size: 5 μm, manufactured by Fukuda Metal Foil & Powder Co., Ltd.] Carbitol and carbon number 13-15
A mixture (30 to 50 parts by weight) of a mixture with a higher alcohol of which the viscosity is adjusted and a curing catalyst p-toluenesulfonic acid (1 to 2 parts by weight) is blended (hereinafter referred to as "silver paste"). Using.

As a transparent substrate, a polyethylene terephthalate (PET) film having a thickness of 100 μm was used.
When the conductive resin composition is printed by intaglio direct printing, a butadiene rubber (JIS-A hardness 30) as a transparent elastomer having a thickness of 2 is formed on the surface of the transparent substrate.
And apply the elastomer at 170 ° C. for 20 minutes.
It was used after being vulcanized for about a minute. The butadiene rubber was used after adding 2 parts by weight of dicumyl peroxide (DOP) as a crosslinking agent to 100 parts by weight of the rubber.

When printing the conductive resin composition by the intaglio direct printing printing method, the intaglio was made of soda-lime glass. Example 1 A silver paste was printed on the surface of the PET film by the intaglio direct printing method, and a printing pattern having square lattice units (Sk / Ss = 5.26, pattern interval 11)
0 μm, and an aperture ratio of 84%).

Then, by heating and curing in a clean oven (100 ° C.) for 20 minutes, a thickness of 10 μm
Pattern was obtained. Thus, the line width Ws, the line interval Wk,
A translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern in which the film thickness Wt and the ratio Sk / Ss were set to the values shown in Table 1 below was obtained.

Examples 2 to 9 Line width Ws and line spacing W of the translucent electromagnetic wave shielding pattern
A light-transmitting electromagnetic wave shielding member was manufactured in the same manner as in Example 1 except that k, the film thickness Wt, and the ratio Sk / Ss were adjusted to have the values shown in Table 1 below. Comparative Example 1 A translucent electromagnetic wave shielding member was manufactured in the same manner as in Example 1 described in JP-A-10-163673.

That is, a mixed solution containing a polyvinyl butyral resin and a palladium catalyst was applied to the entire surface of a PET film as a transparent substrate, and the surface was further subjected to electroless copper plating to form a copper thin film. Next, a photoresist was applied to the entire surface of the copper thin film, and a grid-like resist pattern was formed by exposure and development. Then, the copper plating film was removed by etching with a ferric chloride / hydrochloric acid aqueous solution, and the resist was peeled off. .

Thus, a translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern composed of a copper thin film and having the line width Ws, the ratio Sk / Ss, and the film thickness Wt set to the values shown in Table 1 below was obtained. Comparative Example 2 A translucent electromagnetic wave shielding member was manufactured in the same manner as in Example 1 described in Japanese Patent Publication No. 2-48159.

That is, a UV-curable paste is printed on a PET film as a transparent base material by a screen printing method to form a square grid pattern having a line width Ws of 100 μm and a line interval Wk of 1 mm. Cured. Comparative Example 3 In the same manner as in Example 1 except that a flat plate offset printing method using a waterless lithographic plate (trade name "TAN") manufactured by Toray Industries, Inc. was used instead of the intaglio offset printing method, the light transmission was performed. A conductive electromagnetic wave shielding member was obtained.

Comparative Example 4 A translucent electromagnetic wave shielding member was obtained in the same manner as in Example 1, except that intaglio offset printing using a silicone blanket was used instead of intaglio direct printing. A pattern forming method in each of the above Examples and Comparative Examples,
Table 1 shows the line width Ws, line interval Wk, film thickness Wt, ratio Sk / Ss, and aperture ratio of the electromagnetic wave shield pattern.

[0065]

[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 Effect) A sample of 20 cm × 20 cm was cut out from the electromagnetic wave shielding members obtained in Examples and Comparative Examples, sandwiched in a closed cell, and shielded from electromagnetic waves by the KEC method of Kansai Electronic Industry Promotion Center. The property (shielding effect) was evaluated. In addition, measurement is 0.1-100.
The shielding effect was evaluated in the range up to 0 MHz and the attenuation rate of the electromagnetic wave at 1000 MHz.

The shielding effect of the electromagnetic wave is determined by the attenuation rate (dB).
The larger the better. The evaluation criteria are as follows. A ⁺ : 60 dB or more; very good shielding. A: 50 dB or more and less than 60 dB; electromagnetic wave shielding was good. B: 40 dB or more and less than 50 dB; the shielding property at 1000 MHz was practically sufficient, but 100 MHz or 5
The shielding at 00 MHz was insufficient. C: 20 dB or more and less than 40 dB; the shielding property was insufficient. C ^-: less than 20 dB; shielding property was very poor.

(Visible light transmittance) Using a spectroscopic microscope (“MCPD2000” manufactured by Otsuka Electronics Co., Ltd.), a wavelength of 400 to
Measure the transmittance (%) of 700 nm light (visible light),
The light transmittance was evaluated from the average value. The higher the transmittance, the better the light transmittance. A ⁺ : 90% or more; translucency was extremely good. A: 80% or more and less than 90%; light transmittance was good. A ^-: 70% or more, less than 80%; translucency was practically favorable. B: 50% or more and less than 70%; translucency was insufficient. C: less than 50%; translucency was extremely insufficient.

(Evaluation and Visibility by Visual Inspection) A translucent electromagnetic wave shielding member was adhered to the forefront of the PDP screen, visually observed, and evaluated according to the following criteria. A: No pattern such as unevenness or mesh could be observed over the entire surface. B: Slight unevenness or mesh was observed. C: Patterns such as unevenness and mesh were observed over the entire surface.

(Contrast) A translucent electromagnetic wave shielding member was adhered to the forefront of the PDP screen, and the test pattern displayed on the PDP screen was visually observed and evaluated according to the following criteria. A: The contrast was good and the gradation display was easy to understand. B: The contrast was rather low, and the gradation display was hard to understand. C: The contrast was low and the gradation display was very difficult to understand.

(Comparison of Manufacturing Cost) The cost required for manufacturing the light-transmitting electromagnetic wave shielding member in Example 1 was set to 1, and the ratio of the manufacturing cost by another manufacturing method was determined. Table 2 shows the evaluation results of the respective physical properties of the electromagnetic wave shield pattern portions of the above-mentioned Examples and Comparative Examples.

[0072]

[Table 2]

As is clear from Table 2, in Examples 1 to 9, the electromagnetic wave shielding effect was all good. On the other hand, in Comparative Example 1 in which the formation of the electromagnetic wave shielding pattern was performed by the photolithography method, a large amount of loss occurred in the material for forming the pattern due to the etching process,
There was a problem that the manufacturing cost was extremely high, 10 times that of the first embodiment.

In Comparative Example 2 using the screen printing method for forming the pattern, the minimum line width of the pattern that can be formed without causing a problem such as disconnection is about 100 μm.
There were problems such as a decrease in visibility. In Comparative Example 3, since the planographic offset printing method was used, a pattern having a sufficient film thickness could not be formed, and there was a problem that the shielding performance was extremely low. In the case of lithographic offset printing, a sufficient film thickness can be obtained by repeating the printing several to several tens of times, but the productivity is very poor, the cost is high, and the printing accuracy may be reduced. is there.

In Comparative Example 4 using intaglio offset printing, although the shielding effect of electromagnetic waves was good, the production cost was tripled as compared with the embodiment using intaglio direct printing. was there.

[0076]

As described in detail above, according to the present invention,
It is possible to obtain a low-cost electromagnetic wave shielding member which is excellent in the characteristics of the electromagnetic wave shielding effect, translucency, visibility, and viewing angle, and is low in cost. Therefore, the method for manufacturing a light-transmitting electromagnetic wave shielding member of the present invention is suitable as a method for manufacturing an electromagnetic wave shielding member for a PDP or the like.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing a translucent electromagnetic wave shielding member, FIG. 1 (b) is an enlarged sectional view of AA part thereof, FIG. 1 (c)
FIG. 3 is a sectional view further enlarging the electromagnetic wave shield pattern 10.

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 Transparent electromagnetic wave shielding member 2 Transparent base material 10 Electromagnetic wave shielding pattern 10a Layer made of conductive paste 10b Metal coating Ws Line width Wk Line spacing Wt Film thickness

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[Procedure amendment]

[Submission date] July 6, 1999 (1999.7.6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction contents]

(Line width Ws, film thickness Wt and ratio Sk / Ss
In the translucent electromagnetic wave shielding member of the present invention, the total area Ss of the area where the electromagnetic wave shield pattern is formed on the surface of the transparent base material and the total area Sk of the area where the shield pattern is not formed Ratio Sk / S
s is 1 or more and 9 or less, and the line width Ws of the shield pattern is 5 to 40 μm and the film thickness Wt is 0.5 to 50 μm.
It is preferably in the range of m.

Claims (2)

[Claims] 1. A conductive resin composition containing a metal powder is filled in a concave portion of an intaglio plate, and then the intaglio plate is pressed against the surface of a transparent substrate having a surface coated with a transparent elastomer. And forming an electromagnetic wave shield pattern on the transparent substrate by directly transferring the conductive resin composition in the concave portion. 2. The electromagnetic wave shield pattern has a stripe shape, a lattice shape, or a geometric pattern, and the electromagnetic wave shield pattern has a line width Ws of 5 to 40 μm and a film thickness Wt of 0.
The total area Ss of the electromagnetic wave shield pattern and the total area Sk of a region where the electromagnetic wave shield pattern is not formed is 5 to 50 μm and satisfies the following expression (1): 1 ≦ Sk / Ss ≦ 9. A method for manufacturing a translucent electromagnetic wave shielding member.