JP4880287B2 - Manufacturing method of conductive material - Google Patents

Description

  The present invention relates to a conductive material that can be used for applications such as an electronic circuit, an antenna circuit, an electromagnetic wave shielding material, and a touch panel, and more particularly to a method for producing a transparent conductive material having a metal part and a light transmission part.

  Conventionally, materials having both transparency and conductivity have been used for electromagnetic shielding materials and touch panel applications. As one method of producing such materials, conductive metals such as silver, copper, nickel, and indium are sputtered. A method of forming a metal thin film on a transparent resin film by a method, an ion plating method, an ion beam assist method, a vacuum deposition method, or a wet coating method has been used. However, in this method, the construction method is extremely complicated, and there is a problem that the cost is high and the productivity is poor. Further, there is a limit to improving the conductivity while maintaining the transparency, and in order to form a conductive pattern, it is necessary to perform a process such as etching, which is not suitable.

  Furthermore, electromagnetic waves emitted from plasma display panels, etc., which have become popular recently, have a great influence on surrounding electronic devices and the human body, making it difficult to improve shielding performance and maintain transparency. ing. For such applications, as described in Japanese Patent Application Laid-Open No. 10-41682, by making a lattice pattern subtractively by a photoresist etching method from a film in which copper foil is laminated, conductivity and transparency are created. A method for achieving compatibility between sexes is known. According to this method, not only the lattice pattern but also various conductive patterns can be dealt with. However, this method starts from laminating a transparent film and copper foil, and has to go through a number of steps to obtain the final conductive pattern. Further, since it is a subtractive method, a highly transparent film is obtained. In such a case, there was a drawback that most of the metal eluted without being utilized.

  Under such circumstances, there has been a demand for a method of forming conductive patterns additively by a highly productive method. Since the silver halide photographic light-sensitive material has a high resolving power and the image is metallic silver, it is expected to be a promising candidate for such an application. A proposal has been made for a method for producing a transparent conductive material by subjecting a salt photographic light-sensitive material to image exposure and development, followed by metal plating. However, in concrete implementation, when a commercially available silver halide photographic light-sensitive material is used, the silver image serving as a plating catalyst is buried in a hydrophilic binder, and contact with the plating solution is not easy. However, due to a decrease in catalytic activity due to contamination, metal plating treatment is difficult, and it has not been possible to obtain an advantage over existing methods.

On the other hand, in Japanese Patent Application Laid-Open No. 2004-221564 (Patent Document 2), similarly to Patent Document 1, a conductive pattern is formed by supplying a metal to the silver image from the outside by physical development or plating treatment. It has been disclosed that increasing the silver / gelatin volume ratio improves the efficiency of the plating. However, in the method as disclosed in the publication, it is essential to supply metal from the outside. For example, only silver in the silver halide light-sensitive material can obtain the minimum conductivity for performing electroplating. It was difficult.
WO 01/51276 pamphlet JP 2004-221564 A

  An object of the present invention is to provide a production method for obtaining a conductive material having high transparency and high conductivity with high productivity.

The above object of the present invention has been achieved by using the following method.
(1) Conductivity for forming a conductive pattern by exposing and developing a conductive material precursor containing at least one silver halide emulsion layer on a support and having no physical development nucleus layer In the material manufacturing method, the precursor is processed with a developer that elutes 10 ppm or more of silver ions when processed by 1 square meter per liter of the developer under the development processing conditions in which the exposed area reaches 90% of the maximum density. A method for producing a conductive material.
(2) A method for producing a conductive material, wherein the conductive pattern formed by the method described in (1) is further metal-plated.

  According to the method for producing a transparent conductive material of the present invention, it was possible to provide a production method for obtaining a conductive material having both high transparency and high conductivity and good productivity.

  Examples of the transparent support used for the conductive material precursor of the present invention include polyester resins such as polyethylene terephthalate, diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, polyvinyl chloride, polyimide resins, cellophane, and celluloid. A plastic resin film, a glass plate, etc. are mentioned. Further, in the present invention, an undercoat layer or an antistatic layer for improving the adhesiveness with the silver halide photographic emulsion layer can be provided on the support, if necessary.

  In the conductive material precursor of the present invention, a silver halide emulsion layer is provided on the support as an optical sensor. Techniques used in silver halide photographic films, photographic papers, printing plate-making films, emulsion masks for photomasks, etc. relating to silver halide can also be used as they are in the present invention.

  The halide contained in the silver halide in the present invention may be any of chloride, bromide, iodide and fluoride, and may be a combination thereof, but those having a high chloride ratio are preferred. For the formation of silver halide emulsion grains, methods well known in the art such as forward mixing, reverse mixing, and simultaneous mixing are used. Among them, it is preferable to use a so-called controlled double jet method, which is one of the simultaneous mixing methods and keeps the pAg in the liquid phase to be formed constant, from the viewpoint of obtaining silver halide emulsion grains having a uniform particle size. . In the present invention, the average grain size of preferable silver halide emulsion grains is 0.25 μm or less, particularly preferably 0.05 to 0.2 μm.

  The shape of the silver halide grains in the present invention is not particularly limited. For example, various shapes such as a spherical shape, a cubic shape, a flat plate shape (hexagonal flat plate shape, triangular flat plate shape, tetragonal flat plate shape, etc.), octahedral shape, and tetradecahedral shape are available. It can be a simple shape.

  In the production of the silver halide emulsion in the present invention, a sulfite, a lead salt, a thallium salt, a rhodium salt or a complex salt thereof, an iridium salt or a complex salt thereof is formed in the process of forming silver halide grains or physical ripening as necessary. A group VIII metal element salt or a complex salt thereof may coexist. Further, it can be sensitized by various chemical sensitizers, and methods commonly used in the art such as sulfur sensitization method, selenium sensitization method and noble metal sensitization method can be used alone or in combination. In the present invention, the silver halide emulsion can be dye-sensitized as necessary. In the present invention, the silver halide emulsion does not necessarily have to be negative photosensitive, and may be a direct reversal emulsion having positive sensitivity if necessary.

The silver amount of the silver halide emulsion provided in the conductive material precursor of the present invention is required to be at least 2 g / m ^{2 in} order to give sufficient conductivity by itself. However, if it is too much, there is a problem that a long development time is required or the photosensitivity of the silver halide emulsion grains on the side close to the support is lowered. Therefore, the upper limit should be about 7 g / m ^2. It is. A more preferable range is 4 to 6 g / m ² .

  In the present invention, the silver halide emulsion layer contains a water-soluble polymer as a binder. Preferred binders include, for example, gelatin, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), starch and other polysaccharides, cellulose and derivatives thereof, polyethylene oxide, polyvinylamine, chitosan, polylysine, polyacrylic acid, polyalginic acid, poly Examples include hyaluronic acid and carboxycellulose.

  In the present invention, a hydrophobic polymer may be used in combination with the water-soluble polymer binder for various purposes. Generally, these hydrophobic polymers are used as aqueous dispersions, and known ones such as homopolymers and copolymers of various monomers can be used. Homopolymers include vinyl acetate, vinyl chloride, styrene, methyl acrylate, butyl acrylate, methacrylonitrile, butadiene, and isoprene. Copolymers include ethylene / butadiene, styrene / butadiene, and styrene / p-methoxystyrene. , Styrene / vinyl acetate, vinyl acetate / vinyl chloride, vinyl acetate / diethyl maleate, methyl methacrylate / acrylonitrile, methyl methacrylate / butadiene, methyl methacrylate / styrene, methyl methacrylate / vinyl acetate, methyl methacrylate / vinylidene chloride, methyl acrylate / acrylonitrile , Methyl acrylate / butadiene, methyl acrylate / styrene, methyl acrylate / vinyl acetate, acrylic acid / butyl acrylate, methyl Acrylate-vinyl chloride, butyl acrylate-styrene and the like.

  With respect to the total amount of water-soluble polymer and hydrophobic polymer binder contained in the silver halide emulsion layer, that is, the total amount of binder, if the amount of the binder is small, the coating property is adversely affected, and stable silver halide grains cannot be obtained. On the other hand, if the amount is too large, a decrease in conductivity and a decrease in electroless plating property are observed. The weight ratio (silver / total binder) of the preferred silver halide (in terms of silver) and the total binder is 1.2 or more, more preferably 1.5 to 3.5.

  In the silver halide emulsion layer, known photographic additives can be used for various purposes. These are described in Research Disclosure Items 17643 (December 1978) and 18716 (November 1979) 308119 (December 1989) or cited.

  If necessary, the conductive material precursor in the present invention may be provided with a backing layer or an overlayer on the silver halide emulsion layer on the opposite side of the support from the silver halide emulsion layer.

  Examples of a method for producing a transparent conductive material using the conductive material precursor include formation of a silver thin film having a mesh pattern. In this case, the silver halide emulsion layer is exposed in a reticulated pattern. As an exposure method, a method for exposing the retransmitted original of the reticulated pattern and the silver halide emulsion layer for exposure, or scanning using various laser beams. There are exposure methods. In the above-described method of exposing with laser light, for example, a blue semiconductor laser (also referred to as a violet laser diode) having an oscillation wavelength of 400 to 430 nm can be used.

  As the conductive material precursor, it is preferable to use a non-sensitizing dye or pigment having an absorption maximum in the photosensitive wavelength region of the silver halide emulsion layer as a halation for improving image quality or an irradiation prevention agent. The antihalation agent can be contained in the undercoat layer or the backcoat layer between the silver halide emulsion layer and the support. The irradiation inhibitor is preferably contained in the silver halide emulsion layer. The amount added can vary widely as long as the desired effect is obtained, but when it is contained in the backing layer as an antihalation agent, for example, the range of about 20 mg to about 1 g per square meter is desirable, The optical density at the maximum absorption wavelength is 0.5 or more.

  In the present invention, when the precursor is processed for 1 square meter / 1 liter under the development processing conditions where the exposed area reaches 90% of the maximum attained density, a state of using a developer that elutes 10 ppm or more of silver ions is used. This is essentially different from the presence of silver ions in the developer to some extent. The presence of silver ions in the developer is an effective technique in “physical development” as described on page 12 of Patent Document 2. However, in the present invention, the image is thickened from the outside. Physical development that supplies silver ions is rather inconvenient for achieving the purpose. The elution of silver in the present invention is a silver that is eluted until the exposed area reaches 90% of the maximum density, that is, in the course of chemical development, and is in a new liquid state in which almost no silver ions are present in the liquid. However, as long as a developer satisfying the conditions of the present invention is used, it can be said that this is an embodiment of the present invention.

  The developer in the present invention comprises a developing agent, a preservative, an alkali agent, and an antifoggant as a basic composition. Specific examples of the developing agent include hydroquinone, ascorbic acid, p-aminophenol, p-phenylenediamine, phenidone and the like. Some of these may be contained in the conductive material precursor. Examples of preservatives include sulfite ions, hydroxylamine, and ascorbic acid. The alkaline agent is necessary for exhibiting the reducing ability of the developing agent, and is added so that the pH of the developer is 9 or more, preferably 10 or more. In addition, a buffering agent such as carbonate or phosphate is also used in order to keep the basicity stably. Furthermore, examples of the antifoggant added so that silver halide grains having no development nucleus are not reduced include bromide ions, benzimidazole, benzotriazole, 1-phenyl-5-mercaptotetrazole and the like.

  In the present invention, the precursor is a developer that elutes 10 ppm or more of silver ions when processed by 1 square meter per liter of the developer under the development processing conditions in which the exposed area reaches 90% of the maximum density. Features. In general, silver halides are sparingly soluble, but have non-zero solubility, and the halide composition also increases in solubility as the chloride ratio increases. Further, development conditions such as sulfite, potassium bromide concentration, pH, development temperature and time which are often added to the developer affect the elution of silver ions. Specific methods for increasing the elution of silver ions include 1) increasing the grain size of the silver halide grains of the conductive material precursor or increasing the chloride ratio of the halide composition, and 2) generally developing solutions. 3) adding a soluble silver complex forming agent to the developing solution, and the like. Since the method 1) generally has a certain limit in performance, such as a decrease in sensitivity, the methods 2) and 3) are preferably used in order to satisfy the conditions of the present invention.

  As a soluble silver complex forming agent. Specifically, thiosulfates such as ammonium thiosulfate and sodium thiosulfate, thiocyanates such as sodium thiocyanate and ammonium thiocyanate, sulfites such as sodium sulfite and potassium hydrogen sulfite, 1,10-dithia 18- Thioethers such as crown-6, 2,2'-thiodiethanol, oxadoridones, 2-mercaptobenzoic acid and derivatives thereof, cyclic imides such as uracil, alkanolamines, diamines, described in JP-A-9-171257 Mesoionic compounds, 5,5-dialkylhydantoins, alkylsulfones, and others, 474-475 of "The Theory of the Photographic Process 4th Edition" (TH James, 1977). And compounds described in the section.

  Of these soluble silver complex salt forming agents, alkanolamines are particularly preferred. Examples of the alkanolamine include 2- (2-aminoethylamino) ethanol, diethanolamine, N-methylethanolamine, triethanolamine, N-ethyldiethanolamine, diisopropanolamine, ethanolamine, 4-aminobutanol, N, N- Examples include dimethylethanolamine, 3-aminopropanol, N, N-ethyl-2,2′-iminodiethanol, 2-methylaminoethanol, 2-amino-2-methyl-1-propanol and the like.

  These soluble silver complex salt forming agents can be used alone or in combination. The amount of the soluble silver complex forming agent used is 1 square meter / liter processing from the precursor, and the amount necessary for eluting silver ions of 10 ppm or more is selected. Therefore, it is preferably selected so that the amount of the eluted silver is 10 ppm or more and 100 ppm or less. The development processing temperature is usually selected between 15 ° C and 45 ° C, more preferably 25 ° C to 40 ° C. The present invention is specified by quantifying the silver ions eluted when the exposed area reaches 90% of the maximum attainable density and processed for 1 square meter per liter of the developer. This is because the maximum density on the high-exposure side of the photographic characteristic curve increases as the development progresses, and eventually reaches the peak even if the development is continued, but this is the maximum reached density here. The precursor is developed at 1 square meter / 1 liter under development conditions that reach 90% of the logarithm expressed in logarithm (for example, when the maximum density is 3.0, the maximum density is 2.7). It is specified by quantifying silver ions. As the quantification method, a known method such as titration method, X-ray fluorescence analysis method, atomic absorption spectroscopy method or the like can be used.

  In the present invention, in order to dissolve and remove the undeveloped silver halide emulsion, it is preferable to treat with a fixing solution containing a silver halide solvent. In that case, the precursor that has undergone the development process may be subjected to a stop process before the fixing process. For this, an acidic solution such as a thin acetic acid solution is used.

  As the fixer, thiosulfates such as ammonium thiosulfate and sodium thiosulfate are generally used as a silver halide solvent. In addition, the aforementioned soluble silver complex salt forming agent can be used alone or in combination with thiosulfate. In addition, sulfites and bisulfites can be included as preservatives, and acetic acid, amine borate, phosphates and the like as pH buffers. In addition, water-soluble aluminum (for example, aluminum sulfate, aluminum chloride, potassium alum) as a hardening agent, dibasic acid (for example, tartaric acid, potassium tartrate, sodium tartrate, sodium citrate, lithium citrate) as an aluminum precipitation inhibitor , Potassium citrate and the like). The fixing processing temperature is usually selected between 15 ° C. and 45 ° C., more preferably 25 ° C. to 40 ° C.

  In the present invention, metal plating may be performed for the purpose of enhancing the conductivity of the developed silver portion formed by the exposure and development processing. How much the conductivity is increased depends on the application, but for use as an electromagnetic shielding material used for PDP, for example, while ensuring a transparency of 50% or more, a sheet resistance value of 0.5Ω / □ or less, Preferably 0.1 Ω / □ or less is required.

  In the present invention, electroless plating (chemical reduction plating or displacement plating) and / or electrolytic plating can be used for the plating treatment, but the production method of a highly productive conductive material, which is an object of the present invention, is used. In order to obtain it, it is preferable to perform electrolytic plating directly. Examples of the electroplating method include “Plating Technology Guidebook” (edited by the Technical Committee of Tokyo Sheet Metal Cooperative Association, 1987) p. 75-112 copper sulfate plating or copper pyrophosphate plating, p. It is preferable to perform Watt bath nickel plating or sulfamic acid bath nickel plating described in 127 to 180.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

Example 1
A backing layer having the following composition was applied to a 100-micron-thick polyethylene terephthalate film having a gelatin subbing layer of 0.15 g / m ² .
<Undercoat layer composition / per 1 m ² >
2g of gelatin
Amorphous silica matting agent (average particle size 5μm) 20mg
Dye 1 200mg
Surfactant (S-1) 400mg
1,3-divinylsulfonyl-2-propanol 40mg

Subsequently, a silver halide emulsion layer having the following composition was coated on the surface opposite to the backing layer so that 4 g of silver per 1 m ² and a protective layer 1 g of gelatin per 1 m ² . The following silver halide emulsions A to D were prepared by a general controlled double jet mixing method. Further, these silver halide emulsions were optimally sensitized with gold sulfur using sodium thiosulfate and chloroauric acid according to a conventional method. The silver halide emulsion thus obtained contains 0.3 g of gelatin per gram of silver.

<Silver halide emulsion A>
Chloride 95%, bromide 5%, grain size 0.13 micron <silver halide emulsion B>
70% chloride, 30% bromide, grain size 0.10 micron <silver halide emulsion C>
Chloride 20%, bromide 80%, grain size 0.10 micron <silver halide emulsion D>
98% bromide, 2% iodide, particle size 0.05 microns

<Silver halide emulsion layer composition>
30g gelatin
Silver halide emulsion 300g equivalent to silver 1-phenyl-5-mercaptotetrazole 0.3g
Surfactant (S-1) 3g
1,3-divinylsulfonyl-2-propanol 1.5g

<Protective layer composition>
100g gelatin
Amorphous silica matting agent (average particle size 3.5μm) 1g
Surfactant (S-1) 1g
Surfactant (S-2) 10mg

  The transparent conductive film precursor thus obtained was exposed with a contact negative printer using a halogen lamp as a light source, and a transmission negative original having a mesh pattern with a fine line width of 20 μm and a lattice interval of 300 μm was brought into close contact, and subsequently exposed to Table 1. After being immersed in the following developers A to G at 30 ° C. for 30 seconds with the combination described in 1), the solution was stopped with a 1.5% aqueous acetic acid solution for 15 seconds, and 35 ° C. with a fixer CF-6001 manufactured by Mitsubishi Paper Industries Co. After fixing for 30 seconds, it was washed with water and dried to form a network conductive silver pattern. All the samples showed almost the same total light transmittance, and in particular, no thin line was thinned or thickened.

<Developer A>
Sodium sulfite 50g / L
Hydroquinone 18g / L
1-phenyl-3-pyrazolidone 0.7 g / L
Potassium carbonate 30g / L
Potassium bromide 3g / L
Sodium hydroxide pH = 10.5

<Developer B>
The same developer as Developer A except that the amount of sodium sulfite was changed to 100 g / L

<Developer C>
Developer with 4 g / L of 3,6-dithia 1,8-octanediol added to Developer A

<Developer D>
Developer with 10 g / L of 2- (2-aminoethylamino) ethanol added to Developer A

<Developer E>
Developer solution in which the amount of sodium sulfite in Developer A is 70 g / L and 2- (2-aminoethylamino) ethanol is added at 5 g / L

<Developer F>
Developer A in which the amount of sodium sulfite in Developer A is 70 g / L and 4 g / L of N-methylethanolamine is added

<Developer G>
The developer described in Example 1 (page 17) of JP-A No. 2004-221564, specifically having the following composition.
Hydroquinone 0.037 mole / L
N-methylaminophenol 0.016 mole / L
Sodium metaborate 0.140 mole / L
Sodium hydroxide 0.360 mole / L
Sodium bromide 0.031 mole / L
Potassium metabisulfite 0.187 mole / L

  The sheet resistance value of the mesh conductive silver pattern thus obtained was measured according to JIS K 7194 using a Loresta-GP / ESP probe manufactured by Dia Instruments Co., Ltd., and the results are shown in Table 1. On the other hand, as for the elution of silver ions, first, the sample exposed to the above-mentioned close contact printer through an optical wedge is developed with a developer at 30 ° C. at different times, and the development time when the maximum density reaches 90% of the maximum density is found. Each unexposed sample was processed for 1 square meter per liter of developer at the time found (shown in Table 1), and then the silver ion concentration eluted in the developer was measured using an atomic absorption spectrophotometer (Shimadzu Corporation). Manufactured by AA-670). The results are also shown in Table 1.

  From the results of Table 1, it was possible to easily obtain a transparent conductive material having both high conductivity and light transmittance by the method of the present invention.

(Example 2)
Using a transparent conductive film precursor and a developer having the same combination as in Example 1, a large silver lattice network pattern film having a fine line width of 20 μm and a lattice spacing of 300 μm, having a power feeding part of 1 cm width at both ends in 50 cm square was prepared. This large pattern film was plated using the following copper sulfate plating solution so that the copper thickness would be 6 microns.
<Copper sulfate plating solution>
Copper sulfate pentahydrate 220g
60g of sulfuric acid
1N hydrochloric acid 1.4ml
Total volume 1000ml with water

  The plated state of the plated silver lattice network pattern film thus obtained was observed and summarized in Table 2.

  From the results in Table 2, it was possible to easily obtain a transparent conductive material whose conductivity was further increased by electrolytic plating by the method of the present invention.

Claims (2)

Production of a conductive material comprising a conductive material precursor containing at least one silver halide emulsion layer on a support and having a physical development nucleus layer exposed to light and developed to form a conductive pattern In the method, the precursor is treated with a developer that elutes 10 ppm or more of silver ions when processed at 1 square meter per liter of the developer under the development processing conditions in which the exposed area reaches 90% of the maximum concentration. A method for producing a conductive material.   A method for producing a conductive material, further comprising metal plating the conductive pattern formed by the method according to claim 1.