JP2010262994A - Method of manufacturing light transmissive electromagnetic wave shielding material, and light transmissive electromagnetic wave shielding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light transmissive electromagnetic wave shielding material having a mesh-like conductive layer of superior size precision. <P>SOLUTION: A method of manufacturing the light transmissive electromagnetic wave shielding material includes the processes of: forming an anchor coat layer 12 of 2 to 10 nm in surface roughness Ra by coating a transparent base material 11 with a composition containing a binder resin and particles; forming a mesh-like pretreatment layer 13 by printing an electroless plating pretreatment agent containing composite metal oxide and/or composite metal oxide hydrate, and a composite resin on the anchor coat layer 12 in a mesh-like shape; and forming a mesh-like metal conductive layer 14 on the pretreatment layer 13 through an electroless plating treatment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a method for producing a light-transmitting electromagnetic wave shielding material useful as a front sheet filter of a plasma display panel (PDP), a sticking sheet or the like that can be used for a window of a building such as a hospital that requires an electromagnetic wave shield, The present invention relates to a light transmissive electromagnetic wave shielding material produced by the method and a display panel including the light transmissive electromagnetic wave shielding material.

  In recent years, with the spread of OA equipment, communication equipment, etc., there is a concern about the influence on the human body caused by electromagnetic waves generated from these equipment. In addition, precision devices may malfunction due to electromagnetic waves from mobile phones and the like, and electromagnetic waves are regarded as a problem.

  Therefore, a light-transmitting electromagnetic wave shielding material having an electromagnetic wave shielding property and a light transmitting property has been developed and put into practical use as a front filter for a PDP of an OA device. Such a light-transmitting electromagnetic wave shielding material is also used as a window material for installation of precision equipment such as hospitals and laboratories in order to protect precision equipment from electromagnetic waves.

  In this light-transmitting electromagnetic wave shielding material, it is necessary to satisfy both the light transmitting property and the electromagnetic wave shielding property. For that purpose, for example, (1) a material having an electromagnetic wave shielding layer made of a conductive mesh in which a metal wire or a conductive fiber is made into a net is provided on one surface of a transparent substrate. The Electromagnetic waves are shielded by the conductive mesh portion, and light transmission is ensured by the opening.

  In addition, various types of light transmissive electromagnetic wave shielding materials have been proposed as filters for electronic displays. For example, (2) a transparent substrate provided with a transparent conductive thin film containing metallic silver, (3) a layer of copper foil or the like on the transparent substrate is etched into a net shape, and an opening is provided, (4) a transparent substrate In general, a conductive ink containing conductive powder printed on a mesh is known.

  In such an electromagnetic wave shielding layer, in order to achieve both excellent light transmittance and electromagnetic wave shielding properties, it is necessary to use a mesh-like transparent conductive layer, extremely narrow the line width, and form a very fine pattern. However, with the conventional light-transmitting electromagnetic wave shielding material described above, it has been difficult to achieve both light transmission and electromagnetic wave shielding sufficiently. That is, the light-transmitting electromagnetic wave shielding material (1) has a limitation in thinning, and it is difficult to obtain a fine mesh pattern, and there is a problem that the arrangement of fibers such as misalignment and bending is disturbed. In the case of the light-transmitting electromagnetic wave shielding material (2), there are problems such as insufficient electromagnetic wave shielding properties and strong reflection gloss specific to metals. The light-transmitting electromagnetic wave shielding material (3) has problems such as a long manufacturing process and high cost. Further, in the light transmissive electromagnetic wave shielding material of (4), it is difficult to obtain sufficient electromagnetic wave shielding properties. If the pattern is thickened to increase the electromagnetic shielding properties and the amount of conductive powder is increased, There are problems such as a decrease in permeability.

  Therefore, in Patent Document 1, a mesh-shaped pretreatment is performed on the transparent substrate by printing an electroless plating pretreatment agent containing a composite metal oxide (hydrate) and a synthetic resin on the transparent substrate in a mesh shape. A method for producing a light-transmitting electromagnetic wave shielding material is disclosed which includes a step of forming a layer and a step of forming a mesh-like metal conductive layer on the pretreatment layer by electroless plating.

  According to such a method of Patent Document 1, it is possible to form a pretreatment layer having a fine pattern without generation of stripes or fog by using a highly dispersible composite metal oxide (hydrate). Become. Therefore, it is possible to obtain a metal conductive layer accurately formed with a uniform thickness on the pretreatment layer.

JP 2008-85305 A

  However, even with the method of Patent Document 1, a mesh-like conductive layer having a uniform thickness or a high-definition pattern may not be obtained, and further improvements are required.

  Accordingly, an object of the present invention is to provide a light-transmitting electromagnetic wave shielding material having a mesh-like conductive layer with excellent dimensional accuracy.

  The above-mentioned problem is that the electroless plating pretreatment agent printed on the transparent substrate is distorted or spreads, so that these inks cannot be printed with high accuracy according to the design dimensions, resulting in a fine pattern. This is considered to be caused by the difficulty in forming the mesh-shaped metal conductive layer. As a result of various studies by paying attention to such points, the present inventors have found that the above problem can be solved by forming an anchor coat layer having specific surface roughness including particles.

That is, the present invention
A step of forming an anchor coat layer having a surface roughness Ra of 2 to 10 nm by coating a composition containing a binder resin and particles on a transparent substrate;
On the anchor coat layer, an electroless plating pretreatment agent containing a composite metal oxide and / or composite metal oxide hydrate and a synthetic resin is printed in a mesh shape to form a mesh-shaped pretreatment layer. Process,
The above-mentioned problem is solved by a method for producing a light-transmitting electromagnetic wave shielding material, comprising a step of forming a mesh-like metal conductive layer on the pretreatment layer by electroless plating.

  The method of the present invention is characterized by forming an anchor coat layer having a specific surface roughness using particles. On such an anchor coat layer, the electroless plating pretreatment agent can be printed without causing dripping, repelling, etc., the line width and thickness are uniform, and the dimensional accuracy is excellent (that is, the design) It is possible to easily form a mesh-shaped pretreatment layer (with little difference from the dimension). Furthermore, the anchor coat layer has a large contact area with the pretreatment layer, and the anchor coat layer and the pretreatment layer can be firmly bonded. Therefore, the pretreatment layer and the metal conductive layer are not peeled off in the manufacturing process, and the mesh-shaped metal conductive layer having a uniform thickness and a high-definition pattern can be stably manufactured.

It is explanatory drawing explaining the manufacturing method of this invention along each process.

  FIG. 1 shows a schematic cross-sectional view for explaining each step of the production method of the present invention.

  In the method of the present invention, first, the anchor coat layer 12 having a surface roughness Ra of 2 to 10 nm is formed by applying a composition containing a binder resin and particles on one surface of the transparent substrate 11. (Arrow A1 in FIG. 1). By using the binder resin and the particles, the anchor coat layer 12 having a predetermined surface roughness can be easily formed. Such an anchor coat layer 12 is excellent in adhesiveness with the transparent base material 11 and the mesh-shaped pretreatment layer 13 besides being able to print the electroless plating pretreatment agent with high accuracy.

  Next, an electroless plating pretreatment agent containing a composite metal oxide and / or composite metal oxide hydrate and a synthetic resin is printed on the anchor coat layer 12 in a mesh shape, and the mesh-like pretreatment layer 13 is formed (arrow A2 in FIG. 1). The anchor coat layer 12 has a large contact area with the mesh-like pretreatment layer 13, and the mesh-like pretreatment layer 13 firmly adhered to the anchor coat layer 12 can be formed with high accuracy and easily.

  And the mesh-shaped metal electroconductive layer 14 is formed on the mesh-shaped pretreatment layer 11 by performing an electroless plating process on the metal (arrow A3 in FIG. 1). Since the mesh-shaped pretreatment layer 13 firmly adhered to the anchor coat layer 12 has a fine structure and does not peel off in a subsequent process, the mesh-like pretreatment layer 13 has a uniform shape. The mesh-shaped metal conductive layer 14 having a high-definition pattern with a thickness can be formed.

  Hereinafter, the method of the present invention will be described in detail step by step.

(Anchor coat layer formation process)
In the method of the present invention, a step of forming an anchor coat layer having a surface roughness Ra of 2 to 10 nm is performed by applying a composition containing a binder resin and particles onto a transparent substrate.

  The surface roughness Ra of the anchor coat layer is 2 to 10 nm, more preferably 3 to 9 nm, and particularly preferably 5 to 9 nm. The anchor coat layer having such a surface roughness is not only excellent in the printing accuracy of the electroless plating pretreatment agent, but also excellent in adhesion to the mesh-like pretreatment layer and the transparent substrate. When the surface roughness Ra is less than 2 nm, sufficient adhesion between the pretreatment layer and the anchor coat layer may not be obtained. When surface roughness Ra exceeds 10 nm, there exists a possibility that the pattern precision of the mesh-shaped pretreatment layer formed on an anchor coat layer may fall.

  The surface roughness Ra of the anchor coat layer can be measured using a surface roughness meter (Surfcom 480A manufactured by Tokyo Seimitsu Co., Ltd.) according to JIS B 0601 (1994).

  The average particle size of the particles used for the anchor coat layer is preferably 10 to 50 nm, more preferably 20 to 40 nm. According to the particles having such an average particle diameter, the anchor coat layer having the above-described surface roughness can be easily formed. The average particle diameter of the particles is the average particle diameter of the primary particles of the particles.

  As the particles, transparent inorganic particles such as calcium carbonate, barium sulfate, titanium oxide, alumina, silica, glass, talc, mica, magnesium oxide, zinc oxide and zirconia are preferably used. Of these, alumina, silica, zirconia, and titanium oxide are particularly preferred because an anchor coat layer having excellent adhesion to the pretreatment layer can be obtained.

  The transparent inorganic particles may be subjected to surface treatment with a fatty acid, a silicone coupling agent, a titanate coupling agent, or the like.

  The content of the particles in the anchor coat layer is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, and particularly preferably 10 to 50 parts by mass with respect to 100 parts by mass of the binder resin. . The anchor coat layer containing particles with such a content has a porous structure and is excellent not only in adhesion to the pretreatment layer but also in ink absorbability, and can form the pretreatment layer more accurately. it can.

  Thus, the anchor coat layer preferably has a porous structure. The porous structure preferably has continuous pores in the thickness direction of the anchor coat layer. The anchor coat layer preferably has a porous structure in which pores having an average pore diameter of 0.01 to 10 μm, particularly 0.01 to 1.0 μm are continuous. If the average pore diameter is 0.01 μm, sufficient ink absorbability may not be obtained. Moreover, in the continuous hole whose average hole diameter exceeds 10 micrometers, there exists a possibility that a pretreatment agent may fall in a hole and a pretreatment layer cannot be formed with high precision.

  In the present invention, the average particle size of the particles (primary particles) used in the anchor coat layer is observed at a magnification of about 1,000,000 times with a scanning electron microscope (SEM). The number average value obtained for the projected area equivalent circle diameter is used. The average pore diameter of the anchor coat layer is also the number average value obtained by observing the anchor coat layer with a scanning electron microscope (SEM) at a magnification of about 1,000,000 and obtaining at least 100 pore diameters.

  The glass transition temperature of the binder resin used for the anchor coat layer is preferably 10 ° C. or less, particularly preferably 1 to 10 ° C. The number average molecular weight Mn of the binder resin is in the range of 10,000 to 30,000, preferably 10,000 to 25,000, particularly preferably 15,000 to 25,000. According to such a binder resin, an anchor coat layer excellent in absorbability of the electroless plating pretreatment agent can be formed, and the electroless plating pretreatment agent can be printed with high accuracy.

  In addition, in this invention, the glass transition temperature and number average molecular weight of a synthetic resin can be implemented using the measuring method as described in the Example mentioned later.

  The hydroxyl value of the binder resin is preferably 1 to 10 KOH mg / g, more preferably 4 to 9 KOH mg / g. According to such a binder resin having a hydroxyl group and / or a carboxyl group, it is possible to form an anchor coat layer excellent in absorbability of the electroless plating pretreatment agent.

  In the present invention, the hydroxyl value of the binder resin refers to a value measured based on JIS-K0070.

  Specific examples of the binder resin include acrylic resins, polyurethane resins, and polyester resins. According to these resins, it is possible to form a pretreatment layer that not only has excellent absorbability of the electroless plating pretreatment agent, but also has excellent acid resistance and alkali resistance and can sufficiently withstand electroless plating treatment. Become. Among these, it is particularly preferable to use a polyester resin. The polyester resin preferably has high solubility in a solvent. Therefore, an amorphous polyester resin is particularly preferable.

  Polyester resin reduces melting point and crystallinity by randomly polymerizing part of the acid component or glycol component in polyester such as polyethylene glycol terephthalate or polybutylene glycol terephthalate with other components (copolymerization monomer). Can be produced by imparting solubility. Examples of the acid component used as a comonomer include orthophthalic acid; isophthalic acid; 2,6-naphthalenedicarboxylic acid; aromatic divalent carboxylic acid such as paraphenylenedicarboxylic acid; 1,4-cyclohexanedicarboxylic acid; Alicyclic divalent carboxylic acids, succinic acid; glutaric acid; adipic acid; suberic acid; azelaic acid; sebacic acid and other aliphatic divalent carboxylic acids. Examples of the glycol component include 1,2-propylene glycol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; aliphatic dihydric alcohols such as neopentyl glycol; diethylene glycol; There are polyglycols such as glycol; dipropylene glycol; tripropylene glycol. These comonomers may be used alone or in combination of two or more.

  The composition for forming an anchor coat layer preferably further contains silicone oil in addition to the above-described particles and binder resin. The anchor coat layer containing silicone oil can further improve the printing accuracy of the electroless plating pretreatment agent.

  The content of silicone oil in the anchor coat layer is preferably 0.01 to 0.5 parts by mass, more preferably 0.01 to 0.1 parts by mass with respect to 100 parts by mass of the binder resin.

  Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, and epoxy-modified silicone oil. Of these, dimethyl silicone oil is preferable as the silicone oil.

  The dimethyl silicone oil is generally a dimethylpolysiloxane having a terminal and side chain of a methyl group, and the methylphenyl silicone oil is a part of the methyl group of the side group of the dimethylpolysiloxane having a terminal and side chain of a methyl group. The methyl hydrogen silicone oil is a hydrogenated polysiloxane in which a part of the methyl group of the side group of the dimethylpolysiloxane having a terminal side chain and a methyl group is replaced with hydrogen. Generally, it is a linear silicone oil.

  Alkyl-modified silicone oils, amino-modified silicone oils, and epoxy-modified silicone oils are generally modified polysiloxanes in which the terminal or side chain of the polysiloxane is replaced with an organic group (polyether group, alkyl group, or epoxy group). It is.

  It is preferable that the composition for forming an anchor coat layer further contains an organic solvent. Moreover, you may add a filler, surfactant, etc. to the said composition suitably.

  Examples of the organic solvent include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, isopropyl alcohol, n-butanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2. -Propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, tetrahydrofuran, Examples include 2-methoxyethyl acetate and water. These solvents may be used alone or in a combination of two or more.

  The content of the organic solvent is preferably 60 to 99% by mass, particularly 65 to 80% by mass, based on the total amount of the anchor coat layer forming composition.

  The anchor coat layer is generally formed by applying and curing a composition containing a binder resin, particles, an organic solvent, and, if necessary, silicone oil. As a method for applying the composition, any of existing coating methods such as gravure coating, micro gravure coating, die coating, lip coating, roll reverse coating, wire bar coating, and kiss coating can be employed. Among these, it is preferable to use a micro gravure coat.

  The applied composition can be cured at room temperature, and in that case, for example, it is allowed to stand for 1 to 5 days (particularly 2 to 4 days). If heated, the heating time is shortened according to the temperature. The applied composition is preferably heated to 80 to 140 ° C., particularly 90 to 120 ° C., and cured. The heating time at this time may be about 0.5 to 3 minutes.

  The thickness of the anchor coat layer is preferably 0.1 to 5 μm, particularly preferably 0.1 to 1 μm.

  The transparent substrate on which the composition is applied may be a substrate having transparency (particularly for visible light). Examples of the material include polyester (eg, polyethylene terephthalate (PET), polyethylene naphthalate). (PEN), polybutylene terephthalate), acrylic resin (eg, polymethyl methacrylate (PMMA)), polycarbonate (PC), polystyrene, cellulose triacetate, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyethylene, ethylene-vinyl acetate A polymer, polyvinyl butyral, a metal ion crosslinked ethylene-methacrylic acid copolymer, polyurethane, cellophane and the like can be mentioned. Among these, PET, PEN, PC, and PMMA, which are less transparent due to processing (heating, solvent, bending) and are highly transparent, are preferable.

  The thickness of the transparent substrate varies depending on the use of the light-transmitting electromagnetic wave shielding material, etc., but is usually in the range of 1 μm to 5 mm, particularly preferably in the range of 10 μm to 1 mm.

(Mesh-shaped pretreatment layer forming process)
Next, in the method of the present invention, an electroless plating pretreatment agent containing a composite metal oxide and / or a composite metal oxide hydrate and a synthetic resin is printed in a mesh shape to form a mesh-shaped pretreatment layer. A forming step is performed.

  In electroless plating pretreatment agents, composite metal oxides and composite metal oxide hydrates are excellent in dispersibility, and these are uniformly highly dispersed and fixed at the time of printing. It becomes possible to print on an anchor coat layer in the shape of this. By performing an electroless plating process on such a mesh-shaped pretreatment layer, it is possible to form a fine mesh-shaped metal conductive layer having a small line width.

  The composite metal oxide and composite metal oxide hydrate used for the electroless plating pretreatment agent include those containing at least two metal elements selected from the group consisting of Pd, Ag, Si, Ti, and Zr. Preferably used. More preferably, one containing a metal element of Pd or Ag and a metal element of Si, Ti or Zr is mentioned. Such composite metal oxides and composite metal oxide hydrates have high plating metal deposition ability, and further have excellent stability and dispersibility in the pretreatment agent.

  Especially, since the said characteristic is especially excellent, following formula (I)

(In the formula, M ¹ represents Pd or Ag, M ² represents Si, Ti, or Zr. When M ¹ is Pd, x is 1, and when M ¹ is Ag, x is 2. And n is an integer of 1 to 20). It is particularly preferable to use a composite metal oxide hydrate.

In the formula (I), M ¹ is Pd or Ag, but is preferably Pd. M ² is Si, Ti or Zr, but is preferably Ti. Thereby, the composite metal oxide hydrate having a high plating precipitation ability is obtained.

The specifically as a composite metal oxide _{hydrate, PdSiO 3, Ag 2 SiO 3} , PdTiO 3, hydrates of such Ag ₂ TiO _3, PdZrO ₃ and Ag ₂ TiO ₃ and the like.

  The above-mentioned mixed metal oxide hydrates are obtained by heating each corresponding metal salt, such as hydrochloride, sulfate, nitrate, halide, oxyhalide, hydrate of the corresponding metal oxide, and the like. And obtained by using a hydrolysis method or the like.

As the composite metal oxide, those represented by M ¹ _X · M ² O ₃ (M ¹ , M ² and X are as defined in the above formula (I)) are preferably used.

  The average particle size of the composite metal oxide used for the electroless plating pretreatment agent and the composite metal oxide hydrate is preferably 0.01 to 10 μm, particularly 0.05 to 3 μm. Thereby, it can be set as the composite metal oxide which has the high dispersibility and catalyst activity in which aggregation was suppressed, and the said composite metal oxide hydrate.

  In the present invention, the average particle size of the composite metal oxide and the composite metal oxide hydrate is obtained by observing the cross section of the pretreatment layer with an electron microscope (preferably a transmission electron microscope) at a magnification of about 1,000,000 times. It is set as the number average value which calculated | required the projected area equivalent circle diameter of at least 100 composite metal oxides and the said composite metal oxide hydrate.

  The content of the composite metal oxide and the composite metal oxide hydrate is preferably 10 to 100 parts by mass, more preferably 10 to 70 parts by mass with respect to 100 parts by mass of the synthetic resin. If the content is less than 10 parts by mass, sufficient plating deposition ability may not be obtained, and if it exceeds 100 parts by mass, streaks and fogging based on aggregation of these composite metal oxides may be formed.

  The electroless plating pretreatment agent includes a synthetic resin. Thereby, the adhesiveness of the pretreatment layer to the anchor coat layer and the conductive layer can be improved, the pretreatment layer becomes difficult to peel off, and the conductive layer can be formed more accurately.

  The synthetic resin is not particularly limited as long as adhesion with the anchor coat layer and the conductive layer can be ensured. Preferred examples of the synthetic resin include acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, and ethylene vinyl acetate copolymer resins. Of these, polyurethane resins are preferred. These synthetic resins may be used alone or as a mixture of two or more.

  Examples of polyurethane resins include polyester urethane resins, polyether urethane resins, and polycarbonate urethane resins. Of these, polyester urethane resins are preferred. According to these, high adhesiveness with a transparent base material and a conductive layer is obtained, and a conductive layer can be accurately formed on a pretreatment layer.

  The content of the synthetic resin in the electroless plating pretreatment agent is preferably 10 to 100% by mass, particularly 10 to 30% by mass, based on the total amount of the electroless plating pretreatment agent. Thereby, a pretreatment layer having high adhesion can be formed.

  The mesh-shaped pretreatment layer may be formed using a synthetic resin having a group containing active hydrogen and a polyisocyanate having at least two isocyanate groups. By using the cured layer of the electroless plating pretreatment agent containing these as the pretreatment layer, the adhesion of the pretreatment layer to the metal conductive layer can be further improved.

  Examples of the group containing active hydrogen include a hydroxyl group, a primary amino group, a secondary amino group, and a carboxyl group, and a hydroxyl group is preferable. The equivalent (eg, hydroxyl value) of the group containing active hydrogen is preferably in the range of 10 to 300 mgKOH / g, particularly 30 to 100 mgKOH / g, based on the resin (1 g).

  As polyisocyanate, aromatic polyisocyanates such as tolylene diisocyanate (TDI), isophorone diisocyanate, xylylene diisocyanate, diphenylmethane-4,4-diisocyanate; dicyclopentanyl diisocyanate, hexamethylene diisocyanate, 2,4,4 ' -Trimethylhexamethylene diisocyanate, 2,2 ', 4-trimethylhexamethylene diisocyanate can be mentioned. Polyisocyanates such as trifunctional or higher functional isocyanate compounds such as a TDI adduct of trimethylolpropane can also be used. Of these, aromatic polyisocyanates are preferred.

  The amount of polyisocyanate used in the binder resin is preferably 2 to 30% by mass, particularly 5 to 20% by mass.

  Moreover, the electroless plating pretreatment agent may further contain inorganic fine particles. By containing the inorganic fine particles, it is possible to improve printing accuracy and to form a conductive layer with higher accuracy. Preferred inorganic fine particles include silica, calcium carbonate, alumina, talc, mica, glass flake, metal whisker, ceramic whisker, calcium sulfate whisker, smectite and the like. These may be used individually by 1 type, and may mix and use 2 or more types.

  The average particle size of the inorganic fine particles is preferably 0.01 to 5 μm, particularly preferably 0.1 to 3 μm. If the average particle size of the inorganic fine particles is less than 0.01 μm, the addition of the inorganic fine particles may not improve the printing accuracy as desired, and if it exceeds 5 μm, streaks and fog may be likely to occur. is there.

  The content of the inorganic fine particles in the electroless plating pretreatment agent is preferably 10 to 100 parts by mass, more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the synthetic resin. Thereby, it can be set as the pretreatment agent with high printing appropriateness.

  The electroless plating pretreatment agent may further contain a thixotropic agent. According to the thixotropic agent, the printing accuracy can be improved by adjusting the fluidity of the pretreatment agent, and a conductive layer with higher accuracy can be formed. As the thixotropic agent, any conventionally known thixotropic agent can be used. Preferably, amide wax, hydrogenated castor oil, beeswax, carnauba wax, stearamide, hydroxystearic acid ethylene bisamide and the like can be used.

  The content of the thixotropic agent in the electroless plating pretreatment agent is preferably 0.1 to 20 parts by mass, particularly 1 to 15 parts by mass with respect to 100 parts by mass of the synthetic resin. Thereby, it can be set as the pretreatment agent with high printing appropriateness.

  The electroless plating pretreatment agent of the present invention may further contain a black colorant. Thereby, with the improvement of a printing precision, the glare-proof effect at the time of seeing from the transparent base material side can be provided in the light transmissive electromagnetic wave shielding material obtained.

  Preferred examples of the black colorant include carbon black, titanium black, black iron oxide, graphite, and activated carbon. These may be used individually by 1 type and may be used in mixture of 2 or more types. Of these, carbon black is preferable. Examples of carbon black include acetylene black, channel black, and furnace black. The average particle size of carbon black is preferably 0.1 to 1,000 nm, particularly preferably 5 to 500 nm.

  The content of the black colorant in the electroless plating pretreatment agent is preferably 0.1 to 10 parts by mass, particularly 1 to 5 parts by mass with respect to 100 parts by mass of the synthetic resin. This makes it possible to accurately form a pretreatment layer having an antiglare effect.

  When using a black colorant, it is preferable to prepare the electroless plating pretreatment agent using a commercially available black ink. Examples of such black ink include SS8911 manufactured by Toyo Ink Manufacturing Co., Ltd., EXG-3590 manufactured by Jujo Chemical Co., Ltd., and NT Hiramic 795R Black manufactured by Dainichi Seika Kogyo Co., Ltd. For example, in the case of SS8911 manufactured by Toyo Ink Manufacturing Co., Ltd., the solvent contains vinyl chloride and acrylic resin in addition to carbon black. Therefore, if it is a commercial item, the preparation of the electroless plating pretreatment agent containing the synthetic resin and the black colorant can be easily performed.

  Moreover, it is preferable that the electroless plating pretreatment agent contains an organic solvent. The same organic solvent as that used for the anchor coat layer forming composition is used.

  It is particularly preferable to use an organic solvent that can dissolve the binder resin contained in the anchor coat layer. As such an organic solvent, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), and toluene are particularly preferable. The electroless plating pretreatment agent containing these organic solvents can be printed with high accuracy by dissolving the binder resin contained in the anchor coat layer, thereby suppressing spreading after being printed on the anchor coat layer. it can.

  The content of the organic solvent is preferably 50 to 90% by mass, particularly 65 to 85% by mass with respect to the total amount of the electroless plating pretreatment agent.

  The electroless plating pretreatment agent may further contain various additives such as extender pigments and surfactants as necessary.

  In order to obtain a pretreatment layer having a fine line width and a gap (pitch) by printing, the viscosity of the electroless plating pretreatment agent is preferably 500 to 5000 cps, more preferably 1000 to 3000 cps at 25 ° C. It is good to do.

  In order to print the electroless plating pretreatment agent on the anchor coat layer, a printing method such as gravure printing, flexographic printing, gravure offset printing, screen printing, inkjet printing, electrostatic printing, or the like can be used. In particular, gravure printing and gravure offset printing are suitable for thinning. When using gravure printing, the printing speed is preferably 5 to 50 m / min.

  Thus, after printing the electroless plating pretreatment agent, it is preferably dried by heating at 80 to 160 ° C., more preferably 90 to 130 ° C. If the drying temperature is less than 80 ° C., the evaporation rate of the solvent is slow and there is a possibility that sufficient film formability may not be obtained, and if it exceeds 160 ° C., thermal decomposition of the compound may occur. The drying time for heat drying after coating is preferably 5 seconds to 5 minutes.

  The line width of the mesh-like (including lattice-like) pretreatment layer is generally 25 μm or less, preferably 5 to 20 μm, and particularly 5 to 15 μm. The line pitch is preferably 300 μm or less. Further, the aperture ratio is preferably 75 to 95%, particularly 80 to 95%.

  The shape of the opening surrounded by the line of the pretreatment layer can be an arbitrary shape such as a circle, an ellipse, or a square (quadrangle, hexagon), but is generally a square, and particularly preferably a square. . The lines are net-like, but are preferably grid-like.

  The pretreatment layer has a thickness of 0.01 to 5 μm, preferably 0.1 to 2 μm.

(Reduction treatment process)
In the method of the present invention, after the step of forming the mesh-like pretreatment layer on the anchor coat layer as described above, before the step of forming the mesh-like metal conductive layer, the pretreatment layer is reduced. It is preferable to carry out the step of performing. Reduction treatment reduces the metal species contained in the composite metal oxide and composite metal oxide hydrate that are electroless plating catalysts contained in the pretreatment layer, and only the metal species that are active components are in the form of ultrafine particles. Can be deposited uniformly. Since the metal species thus reduced and deposited have high catalytic activity and are stable, the deposition rate of electroless plating should be improved, and the amount of composite metal oxide (hydrate) used should be reduced. Is possible.

  The reduction treatment is not particularly limited as long as it is a method capable of reducing and complexing the composite metal oxide (hydrate) contained in the pretreatment layer. Specifically, (i) a liquid phase reduction method in which the transparent substrate on which the pretreatment layer is formed is treated with a solution containing a reducing agent, (ii) a transparent substrate on which the pretreatment layer is formed, A gas phase reduction method in which a reducing gas is contacted is preferably used.

  In the liquid phase reduction method, as a method of processing using a solution containing a reducing agent, specifically, a method of immersing the transparent substrate on which the pretreatment layer is formed in a solution containing a reducing agent, A method of spraying a solution containing a reducing agent on the surface on which the pretreatment layer is formed is used.

The solution containing the reducing agent is prepared by dispersing or dissolving a predetermined reducing agent in a solvent such as water. The reducing agent is not particularly limited, but formamide, dimethylformamide, diethylformamide, dimethylacetamide, dimethylacrylamide, sodium borohydride, potassium borohydride, glucose, aminoborane, dimethylamineborane (DMAB), trimethylamineborane (TMAB) ), Hydrazine, diethylamine borane, formaldehyde, glyoxylic acid, imidazole, ascorbic acid, hydroxylamine, hydroxylamine sulfate, hydroxylamine hydrochloride, hypophosphorous acid, hypophosphite such as sodium hypophosphite, hydroxylamine sulfate, Examples thereof include sulfites such as sodium sulfite, hydrosulfite (Na ₂ S ₂ O ₄ : also referred to as sodium dithionite), and the like. If the reducing agent is the same as the reducing agent contained in the electroless plating bath used in the subsequent step, electroless plating can be performed without washing the transparent substrate after the reduction treatment, There is little risk of changing the composition of the electroless plating bath.

  As the reducing agent, aminoborane, dimethylamine borane, sodium hypophosphite, hydroxylamine sulfate, hydrosulfite, and formalin are preferably used because high reducibility can be obtained.

  The content of the reducing agent in the solution containing the reducing agent is preferably 0.01 to 200 g / L, particularly preferably 0.1 to 100 g / L. If the concentration of the reducing agent is too low, it may take a long time to sufficiently perform the reduction treatment, and if the concentration of the reducing agent is too high, the deposited plating catalyst may fall off.

  In the liquid phase reduction method, the pretreatment layer is formed because the composite metal oxide (hydrate) contained in the pretreatment layer is highly reducible as a treatment method using a solution containing a reducing agent. It is preferable to use a method in which the formed transparent substrate is immersed in a solution containing a reducing agent.

  When the transparent substrate is immersed, the temperature of the solution containing the reducing agent is preferably 20 to 90 ° C, particularly 50 to 80 ° C. Further, the immersion time may be at least 1 minute or more, preferably about 1 to 10 minutes.

  On the other hand, when the reduction treatment is performed using the gas phase reduction method, the reducing gas is not particularly limited as long as it is a reducing gas such as hydrogen gas or diborane gas. What is necessary is just to determine suitably the reaction temperature and reaction time at the time of the reduction process using reducing gas according to the kind etc. of reducing gas to be used.

(Process for forming a mesh-like conductive layer)
Next, in the method of the present invention, a step of forming a mesh-like metal conductive layer by electroless plating treatment is performed on the pretreatment layer formed as described above. By performing the electroless plating process, fine metal particles are deposited and formed as a dense and substantially continuous film, and a conductive layer can be selectively obtained only on the pretreatment layer.

  The plating metal can be used as long as it is conductive and can be plated, and may be a single metal, an alloy, a conductive metal oxide, etc. It may be made of fine fine particles.

  As a plating metal in electroless plating, aluminum, nickel, indium, chromium, gold, vanadium, tin, cadmium, silver, platinum, copper, titanium, cobalt, lead, or the like can be used. In particular, silver, copper, or aluminum is preferably used because a conductive layer with high electromagnetic shielding properties can be obtained. Conductive layers formed using these plated metals are excellent in adhesion to the pretreatment layer and are suitable for achieving both light transmittance and electromagnetic shielding properties.

  The electroless plating can be performed at room temperature or under heating according to a conventional method using an electroless plating bath. That is, the plating substrate is immersed in a bath containing a plating solution containing a plating metal salt, a chelating agent, a pH adjuster, a reducing agent, etc. as a basic composition, or a component plating solution is added separately from two or more solutions What is necessary is just to select suitably, such as performing a plating process by a system.

  As an example of electroless plating, when forming a conductive layer made of Cu, a water-soluble copper salt such as copper sulfate 1 to 100 g / L, particularly 5 to 50 g / L, a reducing agent such as formaldehyde 0.5 to 10 g. / L, especially 1 to 5 g / L, containing 20 to 100 g / L, particularly 30 to 70 g / L of a complexing agent such as EDTA, and adjusted to pH 12 to 13.5, particularly 12.5 to 13 A method of immersing a transparent substrate having a treatment layer and an anchor coat layer at 50 to 90 ° C. for 30 seconds to 60 minutes can be employed.

  When performing electroless plating, the substrate to be plated may be rocked and rotated, or the vicinity thereof may be agitated with air.

  The line width of the conductive layer having a mesh shape (including a lattice shape) is generally 25 μm or less, preferably 5 to 20 μm, particularly 5 to 15 μm. The line pitch is preferably 300 μm or less. Further, the aperture ratio is preferably 75 to 95%, particularly 80 to 95%.

  The shape of the opening surrounded by the line of the conductive layer can be any shape such as a circle, an ellipse, and a square (quadrangle, hexagon), but is generally a square, and particularly preferably a square. The lines are net-like, but are preferably grid-like.

  In the method of the present invention, a metal plating layer may be formed on the conductive layer by performing an electroplating process after the step of forming the mesh-shaped conductive layer.

  The material used for the electroplating treatment is not particularly limited as long as the metal plating layer has an excellent electromagnetic wave shielding effect, but for example, copper, nickel, chromium, zinc, tin, silver, gold, etc. A metal is mentioned. These may be used individually by 1 type and may be used as 2 or more types of alloys.

  0.1-10 micrometers is preferable and, as for the thickness of a metal plating layer, 2-5 micrometers is more preferable. When the thickness is less than 0.1 μm, a sufficient electromagnetic shielding effect may not be imparted. On the other hand, when the thickness exceeds 10 μm, the electroplating layer also spreads in the width direction, so that the line width increases, The aperture ratio may be lowered.

  The surface resistivity in the metal plating layer is preferably 3Ω / □ or less, and more preferably 1Ω / □ or less. If the surface resistivity of the metal plating layer exceeds 3Ω / □, the conductivity may be insufficient and the electromagnetic shielding effect may be insufficient.

  In addition, the mesh-like metal conductive layer or metal plating layer may be subjected to blackening treatment, for example, oxidation treatment of the metal layer, black plating of chromium alloy, etc., application of black or dark ink, etc. Can do.

  The light-transmitting electromagnetic wave shielding material obtained by the above-described method of the present invention has a uniform line width and thickness on the anchor coat layer having a predetermined surface roughness and excellent dimensional accuracy (that is, design dimensions and A mesh-like pretreatment layer can be easily formed, and a mesh-like conductive layer having excellent dimensional accuracy can be obtained. Therefore, the light transmissive electromagnetic wave shielding material obtained by the method of the present invention is excellent in electromagnetic wave shielding properties and light transmissive properties.

  The light-transmitting electromagnetic wave shielding material includes a transparent substrate, an anchor coat layer formed on the transparent substrate, a mesh-shaped pretreatment layer formed on the anchor coat layer, and the mesh-shaped pretreatment layer. The anchor coat layer includes a binder resin and particles, and the surface roughness Ra is 2 to 10 nm. The components used for each layer are as described above.

  The light-transmitting electromagnetic wave shielding material according to the present invention is used for applications requiring light transmission, for example, display surfaces of display devices such as LCDs, PDPs, and CRTs of various electric devices that generate electromagnetic waves, or transparent glass for facilities and houses It is suitably applied to surfaces and transparent panel surfaces. Since the light transmissive electromagnetic wave shielding material has high light transmissive property and electromagnetic wave shielding property, it is suitably used for the display filter of the display device described above.

  The display filter of the present invention is not particularly limited, but can be obtained by bonding the light transmissive electromagnetic wave shielding material produced by the above method to a transparent substrate such as a glass plate via an adhesive layer or the like. In such a display filter, the openings of the mesh-shaped pretreatment layer and the metal conductive layer are filled with an adhesive layer.

  In addition to the transparent substrate, the anchor coat layer, the pretreatment layer, the metal conductive layer, and the adhesive layer, the electronic display filter further includes an antireflection layer, a color correction filter layer, a near infrared cut layer, and the like. May be. The order of stacking these layers is determined according to the purpose. Further, the display filter may be provided with an electrode for connecting to the ground electrode of the PDP main body in order to enhance the electromagnetic wave shielding function.

  Hereinafter, the present invention will be described with reference to examples. The present invention is not limited by the following examples.

Example 1
1. Formation of Anchor Coat Layer 15 parts by mass of alumina particles (Al ₂ O ₃ , average primary particle size 20 nm), 84 parts by mass of toluene, and 1 part by mass of a dispersant (unsaturated polycarboxylic acid polyaminoamide) are used for 2 hours in a bead mill. Stirring to prepare an alumina particle dispersion. Next, 100 parts by mass of alumina particle dispersion, polyester resin (number average molecular weight (Mn) 20,000, glass transition temperature (Tg) 7 ° C., Byron (registered trademark) 670: manufactured by Toyobo Co., Ltd.) in methyl ethyl ketone. 30 parts by mass of a solution containing 100 parts by mass, methyl ethyl ketone 358 parts by mass, toluene 446 parts by mass, 2-methoxyethyl acetate 68.5 parts by mass, silicone oil (composition dimethylene silicone) 0.036 parts by mass, and alicyclic isocyanate 4 An anchor coat layer molding composition was prepared by mixing parts by mass.

  On the PET film (thickness 100 μm; S grade; manufactured by Teijin Ltd.), the composition for forming an anchor coat layer was applied by microgravure coating, and then dried at 100 ° C. for 5 minutes to obtain an anchor coat layer (thickness). 0.5 μm) was formed.

2. Formation of mesh-shaped pretreatment layer 60 parts by mass of composite metal oxide hydrate particles (PdTiO ₃ .6H ₂ O, average particle size 0.5 μm) are added to a polyester resin solution (solid content concentration 30% by mass, cyclohexanone to polyester resin) A pretreatment agent was prepared by blending with 100 parts by mass of the solution in which the solution was dissolved.

  Next, after patterning the pretreatment agent on the anchor coat layer by gravure printing, the pretreatment agent was dried at 100 ° C. for 5 minutes to form a mesh-shaped pretreatment layer on the anchor coat layer. As the gravure printing plate, a mold having a groove with a line width of 16 μm, a line depth of 6 μm, and a line interval of 300 μm was used. The mesh-shaped pretreatment layer had a line width of 20 μm and a thickness of 0.5 μm.

Next, the PET film on which the pretreatment layer obtained above was formed was immersed in a sodium hypophosphite solution (NaH ₂ PO ₂ concentration: 30 g / L) at 60 ° C. for 3 minutes, Reduction treatment was performed.

3. Preparation of metal conductive layer The PET film on which the pretreatment layer reduced as described above is formed is immersed in an electroless copper plating solution (Melplate CU-5100 manufactured by Meltex Co., Ltd.) at 50 ° C. for 20 minutes. An electroless copper plating treatment was performed to produce a mesh-like metal conductive layer, and a light-transmitting electromagnetic wave shielding material was obtained. The metal conductive layer had a line width of 23 μm and a thickness of 0.7 μm.

(Example 2)
In the preparation of the anchor coat layer forming composition, the alumina particles (Al ₂ O _3, average primary particle diameter 20 nm) instead of alumina particles (Al ₂ O _3, average primary particle diameter 25 nm) except for using Example In the same manner as in Example 1, a light-transmitting electromagnetic wave shielding material was produced.

(Example 3)
In the preparation of the anchor coat layer forming composition, instead of alumina particles (Al ₂ O ₃ , average primary particle diameter 20 nm), alumina particles (Al ₂ O ₃ , average primary particle diameter 40 nm) are used, and polyester resin (Byron) is used. (Registered trademark) 670: Polyester resin (number average molecular weight (Mn) 25,000, glass transition temperature (Tg) 10 ° C., AD-335A: manufactured by Toyo Morton Co., Ltd.) is used instead of Toyobo Co., Ltd. A light-transmitting electromagnetic wave shielding material was produced in the same manner as in Example 1 except that.

(Comparative Example 1)
A light-transmitting electromagnetic wave shielding material was produced in the same manner as in Example 1 except that the anchor coat layer was not formed.

(Comparative Example 2)
In the preparation of the anchor coat layer forming composition, the alumina particles (Al ₂ O _3, average primary particle diameter 20 nm) instead of alumina particles (Al ₂ O _3, average primary particle diameter 300 nm) except for using Example In the same manner as in Example 1, a light-transmitting electromagnetic wave shielding material was produced.

(Evaluation)
1. Anchor coat layer surface roughness Ra
The surface roughness Ra of the anchor coat layer was measured using a surface roughness meter (Surfcom 480A manufactured by Tokyo Seimitsu Co., Ltd.) according to JIS B 0601 (1994), measurement length 4 mm, cut-off value 0. Measurements were taken at 8 mm. The results are shown in Table 1.

2. Glass transition temperature (Tg)
The glass transition temperature (Tg) of the binder resin used for the formation of the anchor coat layer is 10 ° C./min from −50 ° C. to 100 ° C. using a dynamic viscoelasticity measuring device (RPS-II manufactured by Rheometrics). While increasing the temperature, the temperature dispersion is measured under the conditions of a strain of 1% and a frequency of 1 Hz, and the maximum value of the loss tangent (tan δ) obtained thereby is defined as the glass transition temperature. The results are shown in Table 1.

3. Number average molecular weight Mn
The number average molecular weight Mn of the binder resin used for forming the anchor coat layer was measured under the following conditions. The results are shown in Table 1.

Apparatus: manufactured by Tosoh Corporation, high performance liquid chromatography “HLC-8120GPC”,
Column: manufactured by Tosoh Corporation, “Super H2000 + H4000”, 6 mm D. , 15cm,
Eluent: THF,
Flow rate: 0.500 ml / min,
Detector: RI,
Column bath temperature: 40 ° C
Polystyrene standard.

4). Adhesion of Mesh Pretreatment Layer Cellophane tape (CT24 manufactured by Nichiban Co., Ltd.) was adhered to the mesh pretreatment layer prepared on the anchor coat layer and then peeled off. The peeling state was confirmed visually. The results are shown in Table 1.

  In Table 1, “◎” indicates that no peeling of the mesh-shaped pretreatment layer was observed, and “◯” indicates that peeling was observed in a part of the mesh-shaped pretreatment layer. A sample in which the pretreatment layer was peeled as a whole was designated as “x”.

5). Dimensions of Mesh-like Metal Conductive Layer The line width of the mesh-like metal conductive layer formed on the anchor coat layer was measured. The results are shown in Table 1.

  The light-transmitting electromagnetic shielding material obtained by the method of the present invention has excellent visibility and electromagnetic shielding properties, and is a light-transmitting electromagnetic shielding material particularly suitable for a plasma display panel (PDP) front filter. It is a light-transmitting electromagnetic wave shielding material suitable as a filter for other displays.

  Furthermore, it is a light-transmitting electromagnetic wave shielding material that can be widely used in applications where it is required to avoid the influence of electromagnetic waves. For example, in applications such as display windows provided in precision equipment and window materials in hospitals and laboratories. It is a novel light-transmitting electromagnetic wave shielding material that can be suitably used and has similar advantages.

11 Transparent substrate,
12 Anchor coat layer,
13 mesh pretreatment layer,
14 Mesh-like metal conductive layer.

Claims (13)

A step of forming an anchor coat layer having a surface roughness Ra of 2 to 10 nm by coating a composition containing a binder resin and particles on a transparent substrate;
On the anchor coat layer, an electroless plating pretreatment agent containing a composite metal oxide and / or composite metal oxide hydrate and a synthetic resin is printed in a mesh shape to form a mesh-shaped pretreatment layer. Process,
And a step of forming a mesh-shaped metal conductive layer on the pretreatment layer by electroless plating. A method for producing a light-transmitting electromagnetic wave shielding material, comprising:   The average particle diameter of the said particle | grain is 10-50 nm, The manufacturing method of the light-transmitting electromagnetic wave shielding material of Claim 1 characterized by the above-mentioned.   The method for producing a light-transmitting electromagnetic wave shielding material according to claim 1 or 2, wherein the content of the particles is 5 to 200 parts by mass with respect to 100 parts by mass of the binder resin.   The glass transition temperature of the said binder resin is 10 degrees C or less, and the number average molecular weight Mn exists in the range of 10,000-30,000, The light of any one of Claims 1-3 characterized by the above-mentioned. A method for producing a transparent electromagnetic shielding material.   The light-transmitting electromagnetic wave shielding material according to any one of claims 1 to 4, wherein the binder resin is at least one selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin. Production method.   The electroless plating pretreatment agent includes at least one organic solvent selected from the group consisting of cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, and toluene. Of manufacturing a light-transmitting electromagnetic wave shielding material.   The light transmissive electromagnetic wave shielding material obtained by the method of any one of Claims 1-6. A transparent substrate, an anchor coat layer formed on the transparent substrate, a mesh-like pretreatment layer formed on the anchor coat layer, and a mesh-like metal conductive material formed on the mesh-like pretreatment layer Has a layer,
The light-transmitting electromagnetic wave shielding material, wherein the anchor coat layer contains a binder resin and particles and has a surface roughness Ra of 2 to 10 nm.   9. The light transmissive electromagnetic wave shielding material according to claim 8, wherein an average particle size of the particles is 10 to 50 nm.   The light-transmitting electromagnetic wave shielding material according to claim 8 or 9, wherein the content of the particles is 5 to 200 parts by mass with respect to 100 parts by mass of the binder resin.   The glass transition temperature of the said binder resin is 10 degrees C or less, and the number average molecular weight Mn exists in the range of 10,000-30,000, The light of any one of Claims 8-10 characterized by the above-mentioned. Transparent electromagnetic shielding material.   The light-transmitting electromagnetic wave shielding material according to any one of claims 8 to 11, wherein the binder resin is at least one selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester.   A display filter using the light-transmitting electromagnetic wave shielding material according to claim 7.

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