JP2008130921A - Conductive paste for plating ground, light transmitting window material for electromagnetic wave shielding, and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive paste for a ground with excellent adhesion with plating, to provide a light transmitting window material for electromagnetic wave shielding with excellent adhesion between a conductive base material layer and a plating layer that is formed on the same, and to provide its manufacturing method. <P>SOLUTION: The light transmitting window material for electromagnetic wave shielding 20 comprises a transparent substrate 21, a conductive base material 22 that is formed into a desired pattern on the same, and a plating layer 23 that is formed on this conductive base material 22. For the conductive paste for forming the conductive base material 22, a conductive paste for a plating ground characterized in that the glass transition temperature of a resin is -20 to +40°C is used in the conductive paste for the plating ground containing the resin and conductive particulates. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductive paste for a base of plating containing a resin and conductive fine particles. The present invention also relates to an electromagnetic wave shielding light transmissive window material having a conductive base material layer made of the conductive paste for groundwork and a method for producing the electromagnetic wave shielding light transmissive window material.

  In recent years, with the spread of OA equipment, communication equipment, etc., electromagnetic waves generated from these equipment have been regarded as a problem. That is, there are concerns about the influence of electromagnetic waves on the human body, and malfunctions of precision equipment due to electromagnetic waves are problematic.

  Thus, conventionally, a window material having an electromagnetic shielding property and a light transmission property has been developed and put into practical use as a front filter of a PDP of an OA device. Such a window material is also used as a window material for a precision device installation place such as a hospital or a laboratory in order to protect the precision device from electromagnetic waves such as a mobile phone.

  Conventional electromagnetic shielding light-transmitting window materials are mainly configured by integrating a conductive mesh material such as a wire mesh or a transparent conductive film between transparent substrates such as acrylic plates.

  In general, this conductive mesh has a coarse wire when the wire diameter of the conductive fibers constituting the mesh is large, and the wire becomes fine when the wire diameter is thin. This is because if the fiber has a large wire diameter, it is possible to form a coarse mesh, but it is very difficult to form a coarse mesh with a thin wire diameter.

  For this reason, in the conventional electromagnetic wave shielding light transmission window material using such a conductive mesh, even if the light transmittance is good, it is at most about 70%, and it is not possible to obtain good light transmittance. was there. In addition, the conventional conductive mesh has a problem that moire (interference fringes) is likely to occur due to the pixel pitch of the light emitting panel to which the electromagnetic wave shielding light transmitting window material is attached.

FIG. 3C of Japanese Patent Application Laid-Open No. 2000-196286 discloses an electromagnetic wave shielding light transmitting window material that solves such problems and sufficiently satisfies various characteristics such as electromagnetic wave shielding properties, translucency, visibility, and viewing angle. Is disclosed. FIG. 3 shows FIG. 3 (c) of the same publication. The electromagnetic wave shielding light-transmitting window material of the same publication is obtained by forming an electromagnetic wave shielding pattern 10 on the surface of a transparent substrate 2, and the shielding pattern 10 contains a metal powder and a resin. And a metal film 10b formed by electroplating on the surface of the pattern 10a.
JP 2000-196286 A

  The electromagnetic wave shielding light transmissive window material disclosed in Japanese Patent Application Laid-Open No. 2000-196286 has a problem that the adhesion between the pattern 10a and the metal film 10b is poor.

  An object of this invention is to provide the base conductive paste which is excellent in adhesiveness with plating. Another object of the present invention is to provide an electromagnetic wave shielding light-transmitting window material having excellent adhesion between a conductive base material layer and a plating layer formed thereon, and a method for producing the same.

  The conductive paste for plating base of the present invention (Claim 1) is a conductive paste for plating base containing a resin and conductive fine particles, and the glass transition temperature of the resin is -20 ° C to + 40 ° C. It is a feature.

  The conductive paste for plating base according to claim 2 is characterized in that, in claim 1, the conductive fine particles are metal particles.

  The conductive paste for plating base according to claim 3 is characterized in that, in claim 1 or 2, the content of the conductive fine particles is 400 to 800 parts by mass with respect to 100 parts by mass of the resin. .

  The conductive paste for plating base of claim 4 is characterized in that, in any one of claims 1 to 3, the conductive fine particles have a particle size of 0.1 to 10 μm.

  The electromagnetic wave shielding light transmissive window material of the present invention (invention 5) is an electromagnetic wave shielding light transmissive window material having a transparent substrate and a conductive layer formed on the transparent substrate. An electromagnetic wave shielding light-transmitting window material having a conductive base material layer and a plating film formed on the conductive base material layer, wherein the conductive base material layer is any one of claims 1 to 4. It is characterized by being formed with the conductive paste for plating base of item 1.

  The electromagnetic wave shielding light transmitting window material of claim 6 is characterized in that, in claim 5, an anchor coat layer is formed on the surface of the transparent substrate.

  The method for producing an electromagnetic wave shielding light-transmitting window material of the present invention (invention 7) is to form an electromagnetic wave shielding light by forming a pattern with a conductive paste on a transparent substrate and then forming a plating film on the pattern. In the method for producing a transparent window material, the conductive paste is made of the conductive paste for plating base according to any one of claims 1 to 4.

  The method for producing an electromagnetic wave shielding light-transmitting window material according to claim 8 is the method according to claim 7, wherein an anchor coat layer is formed on a transparent substrate, and a pattern is formed on the anchor coat layer by a conductive paste. A plating film is formed thereon.

  Since the conductive paste for plating base of the present invention has a glass transition temperature of −20 ° C. to + 40 ° C., when a plating layer is formed on the base material layer formed by this conductive paste for base, The adhesion between the substrate layer and the plating layer is extremely excellent.

  Similarly, according to the electromagnetic wave shielding light transmitting window material having the conductive base material layer made of the conductive paste for the base and the manufacturing method thereof, the adhesion between the base material layer and the plating layer is extremely excellent. .

  In the present invention, the conductive fine particles contained in the base conductive paste are preferably metal particles.

  The content of the conductive fine particles is preferably 400 to 800 parts by mass with respect to 100 parts by mass of the resin. The conductive fine particles preferably have a particle size of 0.1 to 10 μm.

  In the electromagnetic wave shielding light transmitting window material of the present invention, an anchor coat layer may be formed on the surface of the transparent substrate.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an electromagnetic wave shielding light transmitting window material 20 and a method for manufacturing the same according to the embodiment. As shown in FIG. 1 (c), the electromagnetic wave shielding light transmitting window material 20 includes a transparent substrate 21, a conductive base material 22 formed in a desired pattern thereon, and an upper surface of the conductive base material 22. And a plating layer 23 formed on the substrate.

  In order to manufacture the electromagnetic wave shielding light transmitting window member 20, first, a conductive paste is formed in a desired shape on a transparent substrate 21 such as a transparent film as shown in FIGS. 1 (a) and 1 (b). By baking, the pattern of the conductive base material 22 is formed. Next, as shown in FIG. 1 (c), a plating layer 23 is formed on the conductive substrate 22. Thereby, the electromagnetic wave shielding light transmission window material 20 is obtained.

  Next, each member will be described.

<Transparent substrate>
As the transparent substrate 21, polyester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polymethyl methacrylate (PMMA), acrylic plate, polycarbonate (PC), polystyrene, triacetate film, polyvinyl alcohol, polychlorinated Vinyl, polyvinylidene chloride, polyethylene, ethylene-vinyl acetate copolymer, polyvinyl butyral, metal ion cross-linked ethylene-methacrylic acid copolymer, polyurethane, cellophane, etc., preferably PET, PEN, PC, PMMA.

  The thickness of the transparent substrate varies depending on the use of the electromagnetic wave shielding light transmitting window material, but is usually about 1 μm to 5 mm.

<Conductive substrate>
As the conductive paste for forming the conductive base material 22, in the conductive paste for the base of the plating containing the resin and the conductive fine particles, the glass transition temperature of the resin is −20 ° C. to + 40 ° C. The characteristic conductive paste for plating base is used.

  The resin contained in the base conductive paste is preferably a polyfunctional isocyanate having one or more main materials such as polyester resin, polyurethane resin, acrylic resin, vinyl acetate resin and having two or more isocyanate groups. A two-component curable material formed by crosslinking with a compound is used.

  The glass transition temperature of this resin is -20 ° C to + 40 ° C, preferably 5 ° C to 15 ° C, particularly preferably 8 ° C to 12 ° C. If the glass transition temperature of this resin is 40 ° C. or lower, the hardness of the surface of the conductive base material formed by this conductive paste for base will be small, so when a plating layer is formed on this surface, this conductive property Destruction at the interface between the base material and the plating layer (interface failure) is less likely to occur. On the other hand, when the glass transition temperature of the resin is −20 ° C. or higher, the conductive base material has high strength, and breakage (cohesive failure) in the conductive base material hardly occurs. In particular, when the transparent substrate 21 is wound at a high speed by the Roll to Roll method, the drying temperature is generally 100 ° C. or lower. However, even when firing at 100 ° C. or lower, or in the base conductive paste Regardless of whether the curing agent is contained or not, the conductive base material has high strength, and cohesive failure of the conductive base material hardly occurs.

  Examples of the conductive fine particles contained in the base conductive paste include powders of silver, copper, nickel, palladium, gold, iron, aluminum, tungsten, chromium, titanium, and the like. A mixture of the above is used. In the present invention, in addition to the powder of the simple metal, a copper powder or nickel powder whose surface is coated with silver may be used. Among the metal powders exemplified above, silver powder is particularly preferably used because it is difficult to produce highly insulating oxides and has low volume resistivity.

  The addition amount of the conductive fine particles is preferably 400 to 800 parts by mass, particularly 600 to 700 parts by mass with respect to 100 parts by mass of the resin. When it is 600 parts by mass or more, the conductivity becomes better. When it is 700 or less, the adhesion to the plating becomes better.

  The conductive fine particles preferably have an average particle size of 0.1 to 10 μm, particularly 0.1 to 5 μm. When the thickness is 0.1 μm or more, the conductivity becomes better, and when it is 10 μm or less, the printability is further improved.

  This conductive paste for base is prepared by adding a solvent to the above resin and conductive fine particles in order to obtain a viscosity suitable for printing.

  Any solvent may be used as long as it dissolves the resin. For example, toluene, ethyl acetate, methyl ethyl ketone (MEK), or the like is preferably used. In order to improve the printability, it is preferable to contain a medium to high boiling point solvent. In this case, 2-broxyethyl acetate, 2- (2-ethoxyethoxy) ethyl acetate, cyclohexanone, xylene, etc. Preferably used.

  The amount of the solvent added is preferably 20 to 50 parts by mass, particularly 20 to 30 parts by mass with respect to the entire base conductive paste.

  This base conductive paste may contain carbon particles. As the carbon particles, those having conductivity and high oil absorption such as ketjen black, channel black, furnace black, lamp black and the like are preferable. The addition amount of the carbon particles is preferably 5 to 20 parts by mass, particularly 10 to 20 parts by mass with respect to 100 parts by mass of the resin.

  The base conductive paste may further contain a dispersant, an adhesion-imparting agent, a curing agent, and the like.

  The base conductive paste has a viscosity of preferably 100 to 10,000 mPas, more preferably 500 to 5000 mPas. When the viscosity is higher than 100 mPas, the pattern shape is more reliably prevented from being deteriorated. Moreover, when the viscosity is lower than 10,000 mPas, the generation of pinholes is more reliably suppressed.

  There is no restriction | limiting in particular as a formation method of a pattern, Well-known pattern formation methods, such as printing, application | coating, vapor deposition, are mentioned. Among these, the printing method is preferable because a conductive pattern having a small line width and a high aperture ratio can be formed. Examples of the printing technique include gravure printing, gravure offset printing, screen printing, flexographic printing, flat plate offset printing, ink jet printing, electrostatic printing, and the like. Among these, the conductive pattern can be made thinner. Gravure printing is particularly preferred. The “aperture ratio” is a value obtained by calculation from the line width of the grid in the grid-like conductive pattern and the number of grids (lines) existing in 1 inch width.

  This base conductive paste is fired, for example, by heating at room temperature to about 120 ° C. for 0.5 to 30 minutes, preferably at 60 to 100 ° C. for 0.5 to 3 minutes. If the temperature is too high or the firing time is too long, the substrate will warp. In addition, firing for 3 minutes or less is preferable for production on a roll-to-roll basis.

  The thickness of the conductive base material 22 varies depending on the use of the electromagnetic wave shielding light transmitting window material, but is usually about 1 to 10 μm.

<Plating layer>
As a plating layer, the film which consists of metals, such as copper, nickel, gold | metal | money, is mentioned, for example. Considering that the surface of the plating layer is oxidized, for example, after plating with copper, the surface is further subjected to nickel plating or gold plating to form a plating film composed of two or more metals. May be.

  The plating layer is preferably formed by electroplating as follows. That is, the transparent substrate 21 on which the conductive base material 22 is formed is immersed in a plating solution for electroplating. Next, an electric current is applied to the plating solution using the transparent substrate 21 as a cathode and a single target metal of plating as an anode.

  The composition of the plating solution used for electroplating is not particularly limited and can be prepared according to a conventional method. For example, when copper plating is formed, a copper sulfate aqueous solution may be used as the plating solution.

  As thickness of a plating layer, 0.1-10 micrometers is preferable and 2-5 micrometers is more preferable. When the thickness is 0.1 μm or more, a sufficient electromagnetic shielding effect can be imparted. When the thickness is 10 μm or less, the plating is suppressed from spreading in the width direction when forming the plating layer, the line width is reduced, and the aperture ratio of the conductive layer is increased.

  The surface resistivity in the plating layer is preferably 3Ω / □ or less, and more preferably 0.1Ω / □ or less. When the surface resistivity of the plating layer is 3Ω / □ or less, the conductivity is sufficient and the electromagnetic wave shielding effect is sufficient.

<Anti-glare layer>
An antiglare treatment may be applied to the surface of the plating layer 23.

  The material of the antiglare layer is not particularly limited as long as it can reduce the reflection of external light when used as a filter on the front surface of a PDP or the like. For example, black or dark ink, etc. Are preferable. Examples of the black or dark color ink include inorganic pigments such as carbon black, organic pigments, oily dyes, disperse dyes, processed pigments in which pigments are dispersed in resins such as urethane and acrylic resins, and the like. . Among these, a processed pigment obtained by dispersing a pigment in a resin such as urethane or acrylic resin is particularly preferable. Further, it is particularly preferable to use a conductive substance so that the antiglare layer is conductive in that it is more excellent in electromagnetic wave shielding properties.

  There is no restriction | limiting in particular as a formation method of a glare-proof layer, Well-known formation methods, such as printing, application | coating, vapor deposition, are mentioned. Among these, it is preferable to form by printing because an antiglare layer can be more suitably formed.

  The thickness of the antiglare layer is preferably from 100 to 10,000 mm, and more preferably from 100 to 1,000 mm. If this thickness is less than 100 mm, the antireflection effect of light may not be sufficient. On the other hand, if it exceeds 10,000 mm, it is difficult to remove the pattern, and the apparent aperture ratio when viewed in perspective is reduced. There are things to do.

  The surface of the plating layer 23 may be blackened. For example, oxidation treatment of a metal film, black plating of a chromium alloy or the like, application of black or dark color ink, or the like can be performed.

  The electromagnetic wave shielding light transmissive window material 10 made of each of these members may be made of a single film, or may be a continuous web-like film unwound from a roll.

  In the electromagnetic wave shielding light transmitting window member 10, the line width of the conductive layer composed of the conductive base material 22 and the plating layer 23 is preferably 1 to 50 μm, particularly preferably 5 to 40 μm. Moreover, it is preferable that an aperture ratio is 50 to 95%, especially 60 to 95%.

  FIG. 2 is a cross-sectional view of an electromagnetic wave shielding light transmitting window material 10A according to a different embodiment. This electromagnetic wave shielding light transmitting window material 10A is formed by forming an anchor coat layer 24 on the surface of a transparent substrate 21, and forming a conductive base material 23 and a plating layer 23 in this order.

  As a material of the anchor coat layer 24, for example, a polyester resin and a curing agent are used. The anchor coat layer 24 is formed on the transparent substrate 21 by micro gravure coating, direct gravure coating, comma coating, or the like.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

In the examples and comparative examples, the composition of ink A used as the base conductive paste is as follows.
Silver particles Ag103W (granular, made by Fukuda Metal): 30 parts by weight AgC239 (flaky, made by Fukuda Metals): 45 parts by weight Resin Polyester resin (“UR2300” manufactured by Toyobo, solid content 30% by weight, glass transition
Temperature (Tg) 10 ° C.): 45 parts by weight Block isocyanate (17B-60PX, solid content 80% by weight, manufactured by Asahi Kasei)
: 2 parts by weight Dispersant: 0.2 parts by weight Solvent: ethyl carbitol acetate: 10 parts by weight

Ink A was obtained by replacing the polyester resin with the following in ink A.
Polyester resin (Toyobo "UR1350", solid content 30% by weight, glass transition
Temperature (Tg) 45 ° C.): 45 parts by weight

Further, the ink A in which the polyester resin was replaced with the following was used as the ink C.
Polyester resin (Toyobo "UR8700", solid content 30% by weight, glass transition
Temperature (Tg) -25 ° C): 45 parts by weight

Example 1
On a transparent PET substrate (thickness 100 μm), the above ink A is printed in a grid pattern with a line width of 50 μm and a pitch of 250 μm by screen printing, and dried at room temperature for one day to form a conductive substrate with a thickness of 5 μm. did.

Thereafter, by performing electroplating (2A / m ² × 5 min) copper sulfate electroplating bath to precipitate a plated layer made of copper on the conductive substrate.

  Thus, an electromagnetic wave shielding light transmitting window material having a conductive layer patterned on a transparent substrate was obtained.

Example 2
Instead of screen printing, gravure printing was performed, and after printing, heating was performed at 100 ° C. for 30 seconds to form a conductive substrate having a thickness of 1 μm. Obtained.

Reference example 1
An electromagnetic wave shielding light-transmitting window material was obtained in the same manner as in Example 1 except that a conductive substrate having a thickness of 5 μm was formed by heating at 130 ° C. for 30 minutes after screen printing.

Comparative Example 1
On the transparent PET substrate (thickness 100 μm), the above ink B is printed in a grid pattern with a line width of 50 μm and a pitch of 250 μm by screen printing, and dried at room temperature for 1 day to form a conductive substrate with a thickness of 5 μm. did.

Thereafter, by performing electroplating (2A / m ² × 5 min) copper sulfate electroplating bath to precipitate a plated layer made of copper on the conductive substrate.

  Thus, an electromagnetic wave shielding light transmitting window material having a conductive layer patterned on a transparent substrate was obtained.

Comparative Example 2
Instead of screen printing, gravure printing was performed, and after printing, heating was performed at 100 ° C. for 30 seconds to form a conductive substrate having a thickness of 1 μm. Obtained.

Comparative Example 3
An electromagnetic wave shielding light-transmitting window material was obtained in the same manner as in Comparative Example 1 except that a conductive substrate having a thickness of 5 μm was formed by heating at 130 ° C. for 30 minutes after screen printing.

Comparative Example 4
On the transparent PET substrate (thickness 100 μm), the above ink C is printed in a grid pattern with a line width of 50 μm and a pitch of 250 μm by screen printing, and dried at room temperature for one day to form a conductive substrate with a thickness of 5 μm. did.

Thereafter, by performing electroplating (2A / m ² × 5 min) copper sulfate electroplating bath to precipitate a plated layer made of copper on the conductive substrate.

  Thus, an electromagnetic wave shielding light transmitting window material having a conductive layer patterned on a transparent substrate was obtained.

Comparative Example 5
Instead of screen printing, gravure printing was performed, and after printing, heating was performed at 100 ° C. for 30 seconds to form a conductive substrate having a thickness of 1 μm. Obtained.

Comparative Example 6
An electromagnetic wave shielding light-transmitting window material was obtained in the same manner as in Comparative Example 4 except that a conductive substrate having a thickness of 5 μm was formed by heating at 130 ° C. for 30 minutes after screen printing.

[Adhesive tape peel test]
A commercially available adhesive tape was affixed to the conductive pattern and peeled off. A case where the conductive layer could not be peeled off was indicated as “◯”, a case where a part of the conductive layer was peeled off, and a case where the conductive layer was widely peeled off. The results are shown in Table 1. In the table, interfacial peeling means that peeling has occurred at the interface between the conductive substrate and the plating layer, and agglomerated peeling means that peeling has occurred on the conductive substrate.

[Electric field shielding effect (dB)]
The window material was cut into 15 × 15 cm and measured by the KEC method under the condition of a frequency of 100 MHz. For the measurement, a shield property evaluation apparatus (manufactured by Anritsu Co., Ltd.) was used. The results are shown in Table 1.

[Magnetic shielding effect (dB)]
It carried out similarly to the measurement of the said electric field shielding effect. The results are shown in Table 1.

  As is clear from Table 1, the electromagnetic wave shielding light-transmitting window material of the present invention is excellent in adhesion between the conductive substrate and the plating layer.

It is sectional drawing explaining the manufacturing method of the electromagnetic wave shielding light transmission window material which concerns on embodiment. It is sectional drawing of the electromagnetic wave shielding light transmission window material which concerns on different embodiment. It is sectional drawing of the conventional electromagnetic wave shielding light transmission window material.

Explanation of symbols

20, 20A Electromagnetic wave shielding light transmitting window material 21 Transparent substrate 22 Conductive base material 23 Plating layer 24 Anchor coat layer

Claims (8)

In the conductive paste for the base of the plating containing resin and conductive fine particles,
A conductive paste for plating base, wherein the resin has a glass transition temperature of -20 ° C to + 40 ° C.   2. The conductive paste for plating base according to claim 1, wherein the conductive fine particles are metal particles.   The conductive paste for plating base according to claim 1 or 2, wherein the content of the conductive fine particles is 400 to 800 parts by mass with respect to 100 parts by mass of the resin.   The conductive paste for plating base according to any one of claims 1 to 3, wherein the conductive fine particles have a particle size of 0.1 to 10 µm. An electromagnetic wave shielding light transmitting window material having a transparent substrate and a conductive layer formed on the transparent substrate,
The conductive layer is an electromagnetic wave shielding light-transmitting window material having a conductive base material layer and a plating film formed on the conductive base material layer.
5. The electromagnetic wave shielding light-transmitting window material, wherein the conductive base material layer is formed of the conductive paste for plating base according to claim 1.   6. The electromagnetic wave shielding light transmitting window material according to claim 5, wherein an anchor coat layer is formed on the surface of the transparent substrate. In a method for producing an electromagnetic wave shielding light transmissive window material by forming a pattern with a conductive paste on a transparent substrate and then forming a plating film on the pattern,
A method for producing an electromagnetic wave shielding light transmissive window material, wherein the conductive paste comprises the conductive paste for plating base according to any one of claims 1 to 4.   8. The electromagnetic wave shielding light according to claim 7, wherein an anchor coat layer is formed on a transparent substrate, a pattern is formed on the anchor coat layer with a conductive paste, and then a plating film is formed on the pattern. A method for manufacturing a transparent window material.

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