JP2012003894A - Conductive paste, electromagnetic wave shielding material using the same, touch sensor and manufacturing method of those - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive paste which is improved so that blur is prevented when screen printing is performed.SOLUTION: In the conductive paste containing an organic binder resin, an organic solvent, and a silver particle as a main component, when rotation speed of a rotor is controlled to be constant to measure viscosity using a rotational viscometer by addition of nitrocellulose of 1 to 5 wt.%, the viscosity is increased gradually with time, and after that, reaches the constant viscosity.

Description

  The present invention generally relates to a conductive paste, and more particularly, to a conductive paste improved so as not to cause fading during screen printing. The present invention also relates to an electromagnetic wave shielding material and a touch sensor obtained by using such a conductive paste, and a manufacturing method thereof.

  A plasma display panel (PDP) is generated when ultraviolet light having a wavelength of 147 nm generated by discharge of He + Ne or Ne + Xe gas in a discharge cell excites phosphors of red (R), green (G), and blue (B). It is a self-luminous display that utilizes the light emission phenomenon. Development is also progressing on display devices with large screens of 50 inches or more that have high brightness, high efficiency, and wide viewing angles.

  From the PDP discharge cell, in addition to RGB visible light, near infrared (NIR), Ne plasma emission, ultraviolet (UV), electromagnetic waves in the range of several MHz to several GHz synchronized with the drive circuit signal required for plasma ignition, etc. The electromagnetic waves that are originally unnecessary for the display are also radiated at the same time. Here, NIR is a malfunction of the wireless remote control, Ne plasma emission is a decrease in the color reproducibility of the display, UV is an adverse effect such as a reduction in visual acuity, and electromagnetic waves in the range of several MHz to several GHz are adverse effects on the human body and the precision equipment. It may cause malfunction. For this reason, a shield film for cutting various harmful electromagnetic waves is attached to the front surface of the PDP.

  As an electromagnetic wave shielding film for shielding electromagnetic waves of several MHz to several GHz band among the various radiated electromagnetic waves, for example, a highly conductive metal is arranged in a lattice pattern on a base film made of a transparent resin such as polyethylene terephthalate. And the like formed with a conductive mesh.

  As a method for producing such an electromagnetic wave shielding film, for example, a copper foil is bonded onto a base film, a resist film is formed in a mesh shape by photolithography or screen printing, and then a portion other than the mesh (opening) Part) is removed by etching (for example, Patent Document 1); a method of performing electroless plating using the catalyst as a core after printing the catalyst on a base film using a gravure printing or offset printing method (For example, patent document 2) etc. are proposed. However, since these methods include wet processes such as etching and electroless plating, there is a problem that the manufacturing is complicated and the cost is high.

  Therefore, the applicants of the present application have said transparent porous layer surface of a transparent resin substrate provided with a transparent porous layer containing as a main component at least one selected from the group consisting of oxide ceramics, non-oxide ceramics and metals. In addition, a method of manufacturing an electromagnetic wave shielding material was proposed in which a conductive paste containing silver particles whose surface is coated with silver oxide, a binder, and a solvent is screen-printed in a geometric pattern (Patent Document 3). This method is convenient because it does not include wet processes such as etching and electroless plating, and is advantageous in that it does not require any consideration of acid resistance, alkali resistance, solvent resistance, etc. of the base film. .

JP 2004-95829 A JP 2007-96049 A JP 2007-142334 A

  However, in the technique disclosed in Patent Document 3, when a conductive paste containing silver particles, a binder, and a solvent is formed on the surface of the transparent porous layer, there is a problem that blurring may occur during screen printing and disconnection may occur.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an improved conductive paste that does not cause blurring during screen printing.

  Still another object of the present invention is to provide an electromagnetic wave shielding material formed using such a conductive paste.

  Still another object of the present invention is to provide a touch sensor including an electrode pattern material formed using such a conductive paste.

  The conductive paste according to the present invention is a conductive paste containing an organic binder resin, an organic solvent, and silver powder as a main component. By adding 1 to 5% by weight of nitrocellulose, the rotational speed of the rotor is measured with a rotational viscometer. When the viscosity is measured with a constant control, the viscosity gradually increases with time and then reaches a constant viscosity.

  Screen printing is a type of stencil printing that uses a screen of chemical fibers such as tetron or nylon, or a stainless steel screen. First, stretch the screen to the frame, pull and fix the four sides to fix it, and make a plate film (resist) on it by handicrafts or optical engineering (photograph) method to close the eyes other than the required lines. make. Next, printing ink is put in the frame, and the inner surface of the screen is pressed and moved with a spatula-shaped rubber plate called a squeegee. Then, the ink passes through the screen where there is no plate film and is pushed out onto the surface of the printing material placed under the plate to perform printing.

  According to the present invention, by adding 1 to 5% by weight of nitrocellulose, the viscosity is gradually increased over time when the rotational speed of the rotor is controlled to be constant with a rotational viscometer and the viscosity is measured. Therefore, the viscosity is only gradually increased when the screen passes through the screen and is extruded onto the surface of the printing material placed under the plate, and then the screen is pulled up. As a result, a large amount of ink flows into the surface of the substrate to be printed, and no fading occurs.

  Content of the said silver powder is 50-95 mass% of the whole quantity of the said electrically conductive paste. By selecting within this range, after firing, in the residual organic binder resin, the silver particles can be kept on the surface of the transparent porous layer with good adhesion while being fused together. The conductive powders stick to each other and are electrically connected, and the conductivity is not impaired.

  The organic binder resin is formed of a synthetic resin.

  Further, the solvent contained in the conductive paste is not particularly limited as long as it does not react with the silver particles and the binder and can be dispersed well. For example, when prepared as a paste for screen printing, a paste having a relatively high boiling point (for example, a boiling point of about 100 to 300 ° C.) is often selected.

  For example, aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, tri Glycol ethers such as propylene glycol normal butyl ether; glycols such as ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate (carbitol acetate), propylene glycol monomethyl ether acetate Ether esters of the organic solvent is used, such as terpineol. The amount of the solvent used may be about 1 to 30 parts by weight, preferably about 3 to 20 parts by weight with respect to 100 parts by weight of the silver particles.

  Since the above-mentioned conductive paste does not cause fading, it is preferable for forming an electromagnetic shielding material. In this case, the method of screen printing is not particularly limited, and can be performed using a known method. The screen plate used for printing has a pattern that can effectively shield electromagnetic waves and form a conductive part to the extent that sufficient transparency can be secured, in particular, a continuous geometric pattern such as a grid or mesh. What you have is used. For example, a screen plate in which a grid pattern having a line width of about 10 to 30 μm and a pattern pitch of about 200 to 400 μm is provided on a 360 to 700 mesh stainless steel basket woven with a stainless wire having a diameter of 11 to 23 μm.

  In general, the line width of a screen-printed pattern tends to be a little thicker in principle than the line width of a screen plate, but there is almost no deviation in line spacing or pattern distortion, and almost the same as the screen plate pattern. A faithful pattern will be reproduced on the transparent porous layer. In the case where the tendency to become thicker is disliked, the slit width of the screen plate may be set smaller than the desired line width formed in the transparent porous layer, and those skilled in the art can easily perform such setting.

  Subsequently, the screen-printed electromagnetic shielding material is heat-treated (baked) at a low temperature of about 130 to 200 ° C. (particularly about 160 to 180 ° C.) to form a conductive portion having a lattice pattern in the transparent porous layer. To do. As described above, since a specific conductive paste is used, no fading occurs, and metal silver particles are easily fused even under relatively low-temperature heating conditions to form a continuous metallic silver coating film. Can do. In the heat treatment, for example, an external heating method (steam or electric heating hot air, infrared heater, heat roll, etc.), an internal heating method (induction heating, high-frequency heating, resistance heating, etc.), etc. are adopted. The heating time is usually about 5 minutes to 120 minutes, preferably about 10 minutes to 40 minutes.

  Note that the heat treatment (firing) may be performed in multiple stages. For example, after the heat treatment at 50 to 60 ° C. for about 10 to 20 minutes as the first step, the heat treatment at 160 to 180 ° C. for about 10 minutes to 40 minutes can be continued as the second step. By using multiple stages, bleeding can be further suppressed by volatilizing the solvent first.

  Further, when the conductive paste is used, a silver coating film can be formed at a low temperature and in a short time, so that adverse effects on the transparent resin substrate due to heat can be avoided. That is, it can suppress that a base material whitens by the oligomer precipitation from a transparent resin base material by heat, or that a base material turns yellow by heat.

  Moreover, when it has a hard-coat layer in the opposite surface to the transparent porous layer of a transparent resin base material, whitening and yellowing of base resin are further suppressed at the time of baking.

  Examples of the transparent resin include polyvinyl alcohol resin, polyester resin, polycarbonate resin, poly (meth) acrylic ester resin, silicone resin, cyclic polyolefin resin, urethane resin, and cellulose resin. The material can be selected from at least one selected from the group consisting of these.

  Moreover, the line width (W) of the grid-like or mesh-like pattern of the conductive part is usually about 10 to 30 μm, preferably about 15 to 20 μm. A geometric pattern having a line width of less than about 10 μm tends to be difficult to produce, and if it exceeds 30 μm, the pattern tends to be noticeable, which is not preferable.

  It should be noted that the interval (pitch) (P) between the lines of the grid-like or mesh-like pattern to be printed can be appropriately selected within a range that satisfies the above aperture ratio and line width. Usually, it may be in the range of about 200 to 400 μm.

  The thickness of the fine line (maximum height of the fine line in the direction perpendicular to the transparent porous layer surface) may vary depending on the line width or the like, but is usually about 1 μm or more, and particularly about 1 to 30 μm.

  The obtained electromagnetic shielding material has a high electromagnetic shielding effect and is excellent in transparency and transparency. In addition, there is a feature that resistance is low because there is almost no disconnection of the thin wire of the conductive portion. The surface resistance value of the electromagnetic wave shielding material of the present invention is 5Ω / □ or less, preferably 3Ω / □ or less, more preferably 2Ω / □ or less. When the surface resistance value is too large, it is not preferable in terms of shielding characteristics.

  The total light transmittance (JIS K7105) of the obtained electromagnetic shielding material can achieve a high value of about 72 to 91%. The haze value (JIS K7105) is as low as about 0.5 to 6%.

  Further, the conductive pattern formed on the transparent porous layer is substantially composed of silver particles, and becomes a lump of high purity silver in which the silver particles are directly fused and bonded. For this reason, the obtained electromagnetic shielding material has a lower and stable resistance value.

  The obtained electromagnetic shielding material may be further laminated with a functional film or the like. The functional film includes an antireflection film provided with an antireflection layer for preventing light reflection on the film surface, a colored film colored by coloring or additives, a near infrared shielding film that absorbs or reflects near infrared rays, and a fingerprint. An antifouling film that prevents the contaminants from adhering to the surface.

  The obtained electromagnetic shielding material has a high electromagnetic shielding effect and is excellent in transparency and transparency. Further, when screen printing is performed using the conductive paste of the present invention, a homogeneous conductive geometric pattern can be easily provided on a substrate with high accuracy. Therefore, even an electromagnetic wave shield front plate applied to a display having a large display area can be easily manufactured. Therefore, it is useful as an electromagnetic wave shielding filter used for a display having a large display screen such as a plasma display panel (PDP) in addition to a cathode ray tube (CRT).

  Moreover, the electrode pattern material formed using the conductive paste of the present invention has no disconnection and is preferable for forming a touch sensor.

  According to another aspect of the present invention, there is provided a method for producing an electromagnetic wave shielding material, the step of forming an ink receiving layer for preventing ink bleeding on a transparent substrate layer, and an organic binder on the ink receiving layer. And a step of forming a geometric pattern by screen printing using a conductive paste containing a resin, an organic solvent, and silver powder as a main component. When the viscosity of the conductive paste is measured by adding 1 to 5% by weight of nitrocellulose and the rotational speed of the rotor is controlled to be constant with a rotational viscometer, the viscosity gradually increases with time, and then the constant viscosity. It is made to reach to.

  According to another aspect of the present invention, there is provided a method for manufacturing an electrode pattern material for a touch sensor, the step of forming an ink receiving layer for preventing ink bleeding on a transparent base material layer, and the ink receiving layer on the ink receiving layer. And a step of forming a geometric pattern by screen printing using a conductive paste containing an organic binder resin, an organic solvent, and silver powder as a main component. When the viscosity of the conductive paste is measured by adding 1 to 5% by weight of nitrocellulose and the rotational speed of the rotor is controlled to be constant with a rotational viscometer, the viscosity gradually increases with time, and then the constant viscosity. It is made to reach to.

  According to the present invention, by adding 1 to 5% by weight of nitrocellulose, the viscosity is gradually increased over time when the rotational speed of the rotor is controlled to be constant with a rotational viscometer and the viscosity is measured. Therefore, when it passes through the screen and is pushed out onto the surface of the printing material placed under the plate, the viscosity gradually increases, remains firmly on the surface of the printing material, and does not cause fading. As a result, the silver fine wire is not broken even after firing.

It is a figure which shows the time dependence of the viscosity of the electrically conductive paste which concerns on this invention and a comparative example. (A) It is a conceptual diagram of the plasma display panel equipped with the electromagnetic wave shielding material formed with the electrically conductive paste which concerns on this invention. (B) It is a top view of the electromagnetic wave shielding material formed with the electrically conductive paste which concerns on this invention. (C) It is sectional drawing which follows the CC line in FIG.2 (B). (A) It is a conceptual diagram of the touch panel containing the electrode material formed with the electrically conductive paste which concerns on this invention. (B) It is a figure explaining operation | movement of a touchscreen.

  In the conductive paste containing an organic binder resin, an organic solvent, and silver powder as a main component, 1 to 5% by weight of nitrocellulose is used for the purpose of obtaining a conductive paste improved so as not to cause fading during screen printing. When the viscosity was measured by controlling the rotation speed of the rotor with a rotational viscometer with a rotational viscometer, the viscosity gradually increased with time, and then adjusted so as to reach a certain viscosity.

  FIG. 1 shows time-dependent curves of various conductive pastes. An R115 viscometer (manufactured by Toki Sangyo) was used as the rotational viscometer. Put 1.5 cc of conductive paste into the sample, sandwich it from above with a cone rotor head, and rotate the head. The torque applied to the head shaft was measured to calculate the viscosity. The paste temperature was adjusted with circulating water and measured at 23 ° C. The rotational speed of the head was controlled by a program. Rotated at 0.6 rpm for the first 60 seconds. It was observed that the viscosity gradually increased at this time. Rotated at 30 rpm from 60 seconds to 130 seconds. At this time, it was observed that the viscosity decreased. Next, after 130 seconds, the viscosity increased (returned) when rotated at 0.5 rpm.

  It has been found that the conductive paste as shown in the viscosity curve a is suitable for the electromagnetic shielding material and the electrode material of the touch sensor. That is, when the rotational speed of the rotor was reduced to 30 rpm with a rotational viscometer and the viscosity was measured by controlling the rotational speed to 0.5 rpm, the viscosity gradually increased with time as shown in the viscosity curve a. It has been found that a conductive paste with an increase in s is preferred. Those exhibiting such a viscosity behavior are pushed through the screen onto the surface of the substrate to be placed under the plate, and when the screen is subsequently lifted, the viscosity increases only gradually. For this reason, it has been found that a large amount of ink flows into the surface of the substrate to be printed and no blur occurs.

It has also been found that such viscosity behavior is caused by the addition of 1-5% by weight of nitrocellulose. Although the mechanism showing such a change in viscosity is not clear due to the addition of nitrocellulose having the following structural formula, cellulose and organic binder, which are the main skeleton of nitrocellulose, are entangled via silver particles, and nitrocellulose contained in nitrocellulose is included. It is thought that the dipole moment derived from the polarization of the group influenced the consistency of the paste (the mechanical resistance that occurs when the liquid is deformed).

  On the other hand, when the rotational speed of the rotor is reduced to 30 rpm with a rotational viscometer as shown in the viscosity curve b and the viscosity is measured by controlling the rotational speed to 0.5 rpm and measuring the viscosity, the viscosity rapidly increases. It has also been found that the conductive paste is blurred during screen printing.

  Examples of the present invention will be described below.

  A 125 μm thick polyethylene terephthalate film (trade name “A4300”, manufactured by Toyobo Co., Ltd.) is used as a transparent resin substrate, and Nippon Paint's NAB-001 film thickness is 1.0 μm on both sides of this film. A reverse gravure coating was applied to the substrate, and UV irradiation was performed to form a hard coat layer. A sol solution in which silica fine particles are dispersed on one side of the film (in which a silica filler having a particle size of 10 to 100 nm is added to an organosiloxane sol solution) is cured to have a film thickness of 1.0 μm. A film was formed and dried at 120 ° C. for 1 minute to produce a transparent substrate of polyethylene terephthalate film having a transparent porous layer (layer thickness: 1.0 μm) of a silica film.

On the porous layer film surface of the film, screen printing of a lattice pattern was performed with a screen printer using the conductive paste shown in Table 1 (content of each component is% by weight). The time dependence of the viscosity of the conductive paste shown in Table 1 was shown by the viscosity curve a in FIG.

  The screen plate is a screen plate (manufactured by Nakanuma Art Screen Co., Ltd.) on a 400-mesh stainless steel basket woven with a stainless wire having a diameter of 23 μm and a grid emulsion pattern having a line width of 20 μm, a pattern pitch of 300 μm, and an aperture ratio of 87.1%. ) Was used.

  After printing, no fading of the conductive paste was observed. The silver compound paste together with the film was baked at 170 ° C. for 30 minutes to form a conductive part in which a square pattern was drawn in a lattice shape, and a transparent conductive film was obtained.

  Even when the lattice-like pattern surface of the obtained transparent conductive film was peeled off with cello tape (registered trademark), the silver paste was hardly peeled off. Moreover, the disconnection part was not recognized.

(Comparative Example 1)
A transparent conductive film was obtained in the same manner as in Example 1 except that the conductive paste shown in Table 2 was used. The time dependence of the viscosity of the conductive paste (content of each component is% by weight) shown in Table 2 is shown by the viscosity curve b in FIG.

  At the time of screen printing, fading was observed on the coated surface of the conductive paste. This is because the ink is not supplied firmly to the surface of the substrate because the viscosity rapidly increases when the screen is pushed through the screen and pushed out to the surface of the substrate placed under the plate. . As a result, blurring occurred.

  FIG. 2A is a conceptual diagram of a plasma display panel equipped with an electromagnetic wave shielding material including a transparent conductive sheet according to the above embodiment. FIG. 2B is a plan view of the electromagnetic wave shielding material, and FIG. 2C is a cross-sectional view taken along the line CC in FIG.

  With reference to these drawings, the electromagnetic wave shielding material 1 is used by being mounted on the display unit 3 of the plasma display panel 2 and blocks electromagnetic waves emitted from the plasma television. The electromagnetic shielding material 1 includes a composite base material (NIRA-HC film base material) in which a PET base material layer 4 (100 μm) and a hard coat layer 5 with a near infrared ray absorbing function 5 (15 μm) are integrated.

  The hard coat layer 5 with a near infrared absorption function is formed by curing a hard coat coating solution with a near infrared absorption function including an inorganic near infrared absorbent, an ultraviolet curable resin, and the like.

  As the inorganic near infrared absorber, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), composite tungsten oxide, or the like can be used. Among them, a composite tungsten oxide is preferable because it has a high near-infrared absorptivity and a high visible light transmittance, and cesium-containing tungsten oxide is most preferable.

  The ultraviolet curable resin includes a monomer, an oligomer, a polymer or a mixture thereof having an ultraviolet curable functional group. Specifically, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, or the like can be used.

  The thickness of the hard coat layer 5 with a near-infrared absorbing function is preferably 2 to 25 μm. The actual film thickness (d) in the examples is 15 μm.

  An antireflection layer 6 (actual film thickness (d) 0.2 μm) is provided on one surface of the composite substrate.

  The antireflection layer 6 is formed by applying and curing a high refractive index layer / low refractive index layer or a low refractive index layer on the coated surface of the hard coat layer 5 with near infrared absorption function. .

  The high refractive index layer is formed by curing a high refractive index layer coating liquid containing an inorganic material, an ultraviolet curable resin, or the like.

  As the inorganic material, zinc oxide, titanium oxide, cerium oxide, tin oxide, aluminum oxide, zirconium oxide, or the like can be used.

  The refractive index of the high refractive index layer needs to be higher than that of the low refractive index layer formed immediately above the high refractive index layer, and the refractive index is preferably in the range of 1.55 to 1.90. Is within.

  The optical film thickness (nd) of the high refractive index layer is preferably 100 nm to 250 nm. The film thickness and refractive index of the examples are optical film thickness (nd): 150 nm and refractive index (n): 1.60.

  The low refractive index layer is formed by curing a coating solution for forming a low refractive index layer containing silica fine particles, a binder component and the like.

  As the silica fine particles, silica sol, porous silica fine particles, hollow silica fine particles and the like can be used. As the binder component, a simple substance or a mixture of a fluorine-containing organic compound, a simple substance or a mixture of a fluorine-free organic compound, a polymer, or the like can be used.

  The refractive index of the low refractive index layer is preferably in the range of 1.20 to 1.45. The optical film thickness (nd) of the low refractive index layer is preferably 100 nm to 175 nm. The film thickness and refractive index of the examples are optical film thickness (nd): 140 nm and refractive index (n): 1.35.

  As the coating method of the hard coat layer 5 with near infrared absorption function and the antireflection layer 6, it was applied on a substrate film by a roll coating method, a spin coating method, a coil bar method, a dip coating method, a die coating method, etc. and dried. Thereafter, there is a method of irradiating with ultraviolet rays. A method capable of continuous coating such as a roll coating method is preferred from the viewpoint of productivity and production cost.

  A transparent porous layer 7 (1 μm), which is an ink receiving layer for preventing bleeding (line thickening) of the conductive paste ink, is provided on the other surface of the PET base material layer 4 (side to be attached to the plasma display panel PDP). Is provided. On the transparent porous layer 7, the electromagnetic wave shielding mesh layer 8 formed by screen-printing the conductive paste ink obtained in Example 1 and firing it is provided.

  Since the conductive paste improved so as not to cause fading during screen printing was used, no disconnection occurred in the silver thin wire.

  The transparent conductive sheet according to the present embodiment is preferably used for an electrode pattern material (touch panel) 9 for a touch sensor as shown in FIG. A transparent base film having a transparent conductive film formed on one side thereof has a configuration in which the transparent conductive films are arranged to face each other at a predetermined interval. The transparent conductive film is formed by screen printing the conductive paste ink obtained in Example 1 and firing it. As shown in FIG. 3B, the capacitive touch panel 9 applies a uniform voltage to the four corners of the sensor to create a uniform electric field on the surface of the sensor. When a finger touches the touch operation (pressing), a change in capacitance is generated in proportion to the distance from the four corners of the sensor to the finger. The controller calculates the coordinate position of the finger based on the capacitance change at the four corners.

  Since the electrode pattern material for the touch sensor according to this example uses a conductive paste improved so as not to cause fading during screen printing, no disconnection occurred in the silver thin wire.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive paste which does not produce a blur at the time of screen printing is obtained, and the electromagnetic wave shielding material and touch sensor without a disconnection can be supplied.

DESCRIPTION OF SYMBOLS 1 Electromagnetic shielding material 2 Plasma display panel 3 Display part 4 PET base material layer 5 Hard-coat layer 6 Antireflection layer 7 Transparent porous layer 8 Electromagnetic wave shielding mesh layer 9 Touch panel

Claims (6)

In a conductive paste containing an organic binder resin, an organic solvent, and silver powder as a main component,
When 1 to 5% by weight of nitrocellulose is added and the rotational speed of the rotor is controlled to be constant with a rotational viscometer and the viscosity is measured, the viscosity gradually increases with time, and then reaches a constant viscosity. A conductive paste characterized by comprising:   2. The conductive paste according to claim 1, wherein a content of the silver powder is 50 to 95 mass% of the total amount of the conductive paste added with 1 to 5 wt% of nitrocellulose.   The electromagnetic wave shielding material formed using the electrically conductive paste of Claim 1 or 2.   The touch sensor containing the electrode pattern material formed using the electrically conductive paste of Claim 1 or 2. Forming an ink receiving layer on the transparent substrate layer to prevent ink bleeding;
On the ink receiving layer, using a conductive paste containing an organic binder resin, an organic solvent, and silver powder as a main component, a step of forming a geometric pattern by screen printing,
When the viscosity of the conductive paste is measured by adding 1 to 5% by weight of nitrocellulose and the rotational speed of the rotor is controlled to be constant with a rotational viscometer, the viscosity gradually increases with time, and then the constant viscosity. The manufacturing method of the electromagnetic wave shielding material characterized by being made to reach | attain. A method of manufacturing an electrode pattern material for a touch sensor,
Forming an ink receiving layer on the transparent substrate layer to prevent ink bleeding;
On the ink receiving layer, using a conductive paste containing an organic binder resin, an organic solvent, and silver powder as a main component, a step of forming a geometric pattern by screen printing,
When the viscosity of the conductive paste is measured by adding 1 to 5% by weight of nitrocellulose and the rotational speed of the rotor is controlled to be constant with a rotational viscometer, the viscosity gradually increases with time, and then the constant viscosity. A method for producing an electrode pattern material for a touch sensor, characterized in that:

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