JP6372689B2 - Conductive paste and conductive pattern forming method - Google Patents

Description

  The present invention relates to a conductive paste for forming a conductive film and a method for forming a conductive pattern.

Printing methods or etching methods are known as methods for forming conductive patterns such as conductive circuits and electrodes used in touch panels, electronic paper, and various electronic components.
When forming a conductive pattern by an etching method, after forming a resist film patterned by photolithography on a substrate on which various metal films are vapor-deposited, an unnecessary vapor-deposited metal film is dissolved and removed chemically or electrochemically, Finally, it is necessary to remove the resist film, and the process is very complicated and poor in mass productivity.

  On the other hand, in the printing method, a desired pattern can be mass-produced at a low cost, and conductivity can be easily imparted by drying or curing the printed coating film. As these printing methods, flexographic printing, screen printing, gravure printing, gravure offset printing, inkjet printing, and the like have been proposed in accordance with the line width, thickness, and production speed of a pattern to be formed. Recently, as a printed pattern, from the viewpoint of downsizing of electronic devices and improvement of design, etc., formation of a high-definition conductive pattern that is currently widely used and difficult to print by screen printing, for example, a line width of 50 μm or less Is required.

  In order to meet the growing demand for thinner, lighter, more flexible electronic devices, and high-productivity roll-to-roll printing, printing on plastic films and firing at low temperature and short time are high. There is a need for a conductive paste that can provide conductivity, substrate adhesion, film hardness, and the like. Further, among plastic films, when printing on a printed material such as a cheap and highly transparent PET film, or a transparent conductive film in which a transparent conductive film of indium tin oxide (ITO) is formed on the PET film, There is a need for a conductive paste that can provide the physical properties described above.

  From this point of view, a method is well known in which a conductive paste containing a polyester resin component is used and printing is performed on, for example, a PET film by a screen printing method, followed by baking to form a conductive pattern. (Refer patent documents 1-4 etc.).

  Each of these conductive pastes used in the prior art contains a polyester resin and a blocked polyisocyanate compound, and is printed and baked with a line width exceeding 30 μm to form a conductive pattern. It has gained.

  Moreover, in the methods described in Patent Documents 1 and 2, although the conductive pattern is finally formed by printing the conductive paste, the pattern shape is unknown, and the method is applied to an actual electronic component. It is formed by connecting two or more linear recesses such as a normal L shape, inverted L shape, U shape, inverted U shape, or B shape in a complicated shape. It has been unclear whether a highly reliable conductive pattern can be obtained even with a complicated shape.

  Conventionally, using a transparent conductive film made of a commercially available transparent conductive film, a mesh pattern, etc. formed through many manufacturing processes, and using a conductive paste, etc., around a complex shape like a bezel pattern An electronic component such as a touch panel is manufactured by printing and baking a conductive pattern corresponding to the wiring.

  In recent years, thinning technology by printing has been further deepened, and has been increased to a level at which formation of a thin line having a line width of 30 μm or less can be studied. If such thinning by printing becomes possible, the industry is attracting attention as an alternative to ITO, which is a transparent conductive film. This is because ITO, which is a material for forming a mesh pattern, which is a complicated conductive pattern, such as a rhombus lattice combination and a hexagonal lattice combination, is a rare metal itself, is expensive and difficult to obtain, inorganic Not only does it suffer from inferior flexibility because it is a film, but it requires many complicated manufacturing processes such as vapor deposition, exposure, and cleaning to form ITO patterns, for example, for use in touch panels. This is because productivity is inferior.

JP 2002-94201 A JP 2003-223812 A JP 2003-272442 A JP 2008-171828 A

  From only the polyester resin, the blocked polyisocyanate compound, and the organic solvent, it is difficult to obtain appropriate printing characteristics, and it is difficult to print fine lines such as a line width of 30 μm or less. Therefore, the technical problem to be solved by the present invention is to provide a conductive paste containing a polyester resin and a blocked polyisocyanate compound that can be printed with a narrower line width and can form a conductive pattern. There is.

  If it is possible to print not only peripheral wiring like a conventional bezel pattern but also a mesh pattern with a narrower line width, which has been conventionally obtained based on an ITO transparent conductive film, with a conductive paste, the transparent conductive film In addition to facilitating the flexible wiring portion corresponding to the above, it is possible to manufacture an electronic component such as a touch panel with high productivity without going through multiple steps such as vapor deposition to cleaning. In addition, if the bezel pattern and the mesh pattern can be formed by only one printing, the productivity improvement in manufacturing an electronic component such as a touch panel becomes extremely remarkable.

  Therefore, in order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, it is difficult to solve the problem by using an organic solvent alone by using a polyester resin that is solid at 50 ° C. and a polyester diol that is liquid at 50 ° C. In addition, the inventors have found that the above-described drawbacks can be solved, and have completed the present invention.

That is, the present invention relates to conductive metal particles (A), a polyester resin (B) that is solid at 50 ° C., a polyester diol (C) that is liquid at 50 ° C., a blocked polyisocyanate compound (D), and (A ) To (D) and an organic solvent (E) having a boiling point of 170 to 300 ° C. at normal pressure not having reactivity, and a conductive paste for conductive pattern printing.
The present invention also includes a gravure plate provided with a recess including a pattern filled with a paste, a doctor for filling the recess of the gravure plate with a paste, a blanket for passing the paste from the recess of the gravure plate, and the blanket. A method for forming a conductive pattern by a gravure offset printing method, in which a printed material is supplied so as to be opposed to each other, a pattern corresponding to a fine wiring pattern on a blanket is printed on the printed material, and then fired. The method for forming a conductive pattern is characterized in that the conductive paste described above is used as the paste.

  Since the conductive paste of the present invention is prepared by using a polyester resin that is solid at 50 ° C. and a polyester diol that is liquid at 50 ° C., the conductive paste has a complicated shape such as a bezel pattern or a mesh pattern. Even when a pattern corresponding to the above is printed, the intended conductive pattern having excellent linearity and free from disconnection or short circuit can be obtained.

It is a top view which shows an example of the bezel pattern used by this invention. It is a top view which shows the square lattice pattern which is an example of the mesh pattern used by this invention. It is a top view which shows the random lattice pattern which is an example of the mesh pattern used by this invention.

  The conductive paste of the present invention comprises conductive metal particles (A), a polyester resin (B) that is solid at 50 ° C., a polyester diol (C) that is liquid at 50 ° C., and a blocked polyisocyanate compound (D). It is the conductive paste for conductive pattern printing containing the said (A)-(D) and the organic solvent (E) with a boiling point of 170-300 degreeC in the normal pressure which does not have reactivity.

(Conductive metal particles)
Any known material can be used as the conductive metal particles (A) used in the present invention. For example, nickel, copper, gold, silver, aluminum, zinc, nickel, tin, lead, chromium, platinum, palladium, tungsten, molybdenum, etc., and an alloy or mixture of these two or more, or a compound of these metals is good. Examples include those having conductivity. In particular, silver powder is preferable because it can easily realize stable conductivity and has good heat conduction characteristics. The conductive metal particles (A) in the present invention have a median particle size (D50) of 0.1 to 10 μm as an average particle size, and 0.1 to 0.7 μm in order to form a finer wire. It is preferable to use conductive metal particles.

(Silver powder)
When using silver powder as the conductive metal particles (A) in the present invention, it is preferable to use spherical silver powder having a median particle diameter (D50) of 0.1 to 0.7 μm as an essential component. This range is less likely to cause trouble even when continuously printed on a printing press in the gravure offset printing method, and it becomes easy to obtain a stable conductive pattern. If necessary, spherical silver powder having a median particle size (D50) of 0.1 to 0.7 μm and silver powder having a median particle size larger than that may be used in combination.

  Examples of silver powder include AG2-1C (manufactured by DOWA Electronics Co., Ltd., average particle size D50: 0.8 μm), SPQ03S (manufactured by Mitsui Kinzoku Co., Ltd., average particle size D50: 0.5 μm), EHD (Mitsui Metal Industry Co., Ltd., average particle size D50: 0.5 μm), Sylbest C-34 (Tokuriku Chemical Laboratory Co., Ltd., average particle size D50: 0.35 μm), AG2-1 (DOWA Electronics Co., Ltd.) Manufactured, average particle diameter D50: 1.3 μm), Sylbest AgS-050 (manufactured by Tokuru Chemical Laboratory, average particle diameter D50: 1.4 μm), and the like.

  Even if the conductive metal particles (A) have no surface coating or have exposed metal surfaces, the surfaces are preliminarily surfaced with various fatty acids or salts thereof, polar or nonpolar surfactants, etc. It may be coated or a metal oxide may exist on a part of the metal surface.

  The conductive paste of the present invention contains a polyester resin (B) component that is solid at 50 ° C. and a polyester diol (C) component that is liquid at 50 ° C. as the organic compound component of the nonvolatile content. Each of these polyester components integrally forms a dry film after printing, and the conductive metal particles (A) are fixed onto a substrate to be described later.

(Polyester resin solid at 50 ° C)
The polyester resin (B) which is solid at 50 ° C. used for the conductive paste of the present invention can form a good film by itself, and can form a good film on a blanket as described later. The strike coating allows complete transfer from the blanket to the substrate. It is preferable that it itself is solid at 50 ° C., has a boiling point of more than 300 ° C. at normal pressure, is soluble in an organic solvent (E) described later, and is easily melted and fluidized at a firing temperature or lower.

  As such a polyester resin (B), for example, a divalent carboxylic acid derivative selected from the group consisting of a dihydric alcohol and a divalent carboxylic acid, a divalent carboxylic acid alkyl ester or a divalent carboxylic acid halide is an essential component. As necessary, a trivalent or higher polyhydric alcohol, a trivalent or higher polyvalent carboxylic acid or a trivalent or higher polyvalent carboxylic acid derivative may be used in combination. The production method of the polyester resin (B) used in the present invention is not particularly limited, and for example, any of a dehydration condensation reaction, an ester exchange reaction, and a dehydrohalogenation reaction may be employed under known and usual conditions. I can do it.

  Examples of the divalent carboxylic acid used to obtain the polyester resin (B) used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid, succinic acid, Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid and other aliphatic dicarboxylic acids, dibasic acids having 12 to 28 carbon atoms, 1,4-cyclohexanedicarboxylic acid 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 1,2-cyclohexene-1,2-dicarboxylic acid, 3, 4-cyclohexene-1,2-dicarboxylic acid, 2-methylhexahydro Hydrophthalic acid, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, bicyclo [2.2.1] heptane-2,3-dicarboxylic acid, methyl bicyclo [2.2. 1] Alicyclic dicarboxylic acids such as heptane-2,3-dicarboxylic acid, hydrogenated naphthalenedicarboxylic acid, and tricyclodecane dicarboxylic acid. Further, esterified products with these acid anhydrides, lower alcohols and the like can also be used. Examples of the divalent carboxylic acid alkyl ester and the divalent carboxylic acid halide include the divalent carboxylic acid alkyl ester esterified with the above-described divalent carboxylic acid and alcohol, and the divalent carboxylic acid halide. And divalent carboxylic acid halides halogenated with carboxylic acid and hydrogen halide.

  In addition to the divalent carboxylic acid or divalent carboxylic acid derivative, for example, trivalent or higher carboxylic acids such as trimellitic anhydride and pyromellitic anhydride, and fumaric acid can be used as long as the effects of the present invention are not impaired. A saturated divalent carboxylic acid, and a sulfonic acid metal base-containing dicarboxylic acid such as sodium 5-sulfoisophthalate may be used in combination.

  Examples of the polyester resin (B) used in the present invention include a polyester resin containing a condensation structure derived from an aliphatic dicarboxylic acid having 6 to 8 repeating units of methylene bonds, such as suberic acid, azelaic acid, and sebacic acid. It is preferable in terms of dispersibility and fluidity of the metal particles.

  Specifically, when the total of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid constituting the polyester resin is 100 mol%, 33% or more of the aliphatic dicarboxylic acid of the repeating units 6 to 8 of the methylene bond, Of these, 33 to 50 mol% is preferable from the viewpoints of coating film properties such as hardness and adhesion, and moisture resistance.

  Examples of the dihydric alcohol used for obtaining the polyester resin (B) used in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol. 2-methyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl -1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexane Dimethanol, 1,2-cyclohexanedimethanol, dimer diol, hydrogenated bisphenol A, and the like.

  In addition to the dihydric alcohol, a trihydric or higher polyhydric alcohol such as trimethylol ethane, trimethylol propane, glycerin, pentaerythritol, polyglycerin may be used in combination as long as the content of the invention is not impaired.

As the dihydric alcohol or the trihydric or higher polyhydric alcohol, the above-mentioned polyhydric alcohols such as ethylene oxide, propylene oxide, tetrahydrofuran, and ε-caprolactone can be used.

  Of these, from the viewpoint of various physical properties of the conductive paste itself, the printed pattern from it, or the conductive pattern after firing, the total alcohol component amount is 100 mol%, and the number of carbon atoms is 2 to 6 carbon atoms. It is preferable that the following aliphatic diol is 80-100 mol%. Examples of the aliphatic diol having 2 to 6 carbon atoms and 6 or less carbon atoms include ethylene glycol, butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol and the like.

  The dicarboxylic acid and its derivatives and diols as described above may be reacted by charging these raw materials all at once into the reaction vessel, or by adding them stepwise into the reaction vessel, random structure, block structure, Various polyester resins having a structure including both can be prepared.

  The polyester resin (B) used in the present invention is itself solid at 50 ° C. Examples of such a polyester resin that is solid at 50 ° C. include polyester resins having a polystyrene-reduced number average molecular weight (Mn) of 10,000 to 40,000 by gas chromatography (GPC).

  In addition, since such a polyester resin (B) itself is poor in fluidity, the blocking agent of the blocked polyisocyanate compound (D) described later is dissociated to form a polyisocyanate compound, and when reacted with this, Further, the molecular weight is increased and the fluidity is lowered. Therefore, the polyester resin (B) is a polyester resin having a lower acid value and a lower hydroxyl value, particularly an acid value of 5 mgKOH / g or less and a hydroxyl value of 10 mgKOH / g or less so that the reactivity with the polyisocyanate compound becomes smaller. It is preferable that

The polyester resin (B) can be produced by a dehydration condensation, a transesterification reaction, a dehydrohalogenation reaction or the like using a known and conventional apparatus and known and conventional reaction conditions (reaction temperature, reaction time, catalyst). In addition, the reaction can be terminated by lowering the heating temperature, diluting with an organic solvent inert to the above reaction, or adding monoalcohol or the like.

(Liquid polyester diol at 50 ° C)
The polyester diol (C) which is liquid at 50 ° C. used for the conductive paste of the present invention is different from the polyester resin (B) which is solid at 50 ° C., and the blocking agent is obtained from the blocked polyisocyanate compound (D) described later. It reacts with the polyisocyanate compound produced by dissociation to produce a polyurethane resin, and this polyurethane resin forms a good film together with the polyester resin (B). Those which are soluble in the organic solvent (E) described later and are more easily flowable are preferred.

  Such a polyester diol (C) is obtained from, for example, a divalent carboxylic acid derivative selected from the group consisting of a dihydric alcohol and a divalent carboxylic acid, a divalent carboxylic acid alkyl ester, or a divalent carboxylic acid halide. Examples include polyester diol. For the production of the polyester diol (C), any of the raw materials and reaction conditions used to obtain the above-described polyester resin (B) can be employed. Unlike the above-described polyester resin (B), the reaction is performed so that both terminal functional groups of the polyester are hydroxyl groups. Polyester diol (C) can be easily obtained by, for example, charging raw materials and reacting them so that the number of moles used is higher in dihydric alcohol than in divalent carboxylic acid or divalent carboxylic acid derivative. It is done.

  The polyester diol (C) which is liquid at 50 ° C. used in the present invention is itself liquid at 50 ° C. and has excellent fluidity. Examples of the polyester diol that is liquid at 50 ° C. include polyester diols having a number average molecular weight (Mn) of 3,000 or less in terms of polystyrene by gas chromatography (GPC).

  Such a polyester diol (C) is used for the purpose of positively reacting with the polyisocyanate compound by dissociating the blocking agent of the blocked polyisocyanate compound (D) described later. For this reason, the polyester diol (C) has an appropriate hydroxyl value range equal to or more than the equivalent of the isocyanate equivalent of the polyisocyanate compound produced from the blocked polyisocyanate compound so that the reactivity with the polyisocyanate compound is greater. Among these, a polyester diol having a hydroxyl value of 40 to 300 mgKOH / g is preferable.

  In the above description, the polyester resin (B) is preferably a polyester resin containing a condensed structure derived from an aliphatic dicarboxylic acid having 6 to 8 repeating units of methylene bonds. Alternatively, a polyester diol containing a condensed structure derived from an aliphatic dicarboxylic acid having 6 to 8 repeating units of methylene bonds may be used.

  Since both the polyester resin (B) and the polyester diol (C) have a polyester structure, the compatibility of both is excellent, and since the polyester diol (C) is liquid, the solid polyester resin (B) Easy to mix with. For this reason, the conductive paste prepared by mixing with the blocked polyisocyanate compound (D) and the organic solvent (E) having a boiling point of 170 to 300 ° C. at normal pressure is good on a blanket as described later. It is possible to facilitate the formation of a film and the complete transfer of the paste film from the blanket to the substrate.

  Formed as a pattern on the printed material in a form that further contains a polyurethane resin produced by the reaction between the polyester diol (C) and the polyisocyanate compound. The property becomes better. In addition, since the polyester diol (C) partially functions as a solvent for the polyester resin (B), the non-volatile content of the conductive paste is increased, specifically, an organic solvent having a boiling point of 170 to 300 ° C. at normal pressure. It is also possible to further reduce the amount of use of (E).

  The mass ratio of the polyester resin (B) that is solid at 50 ° C. and the polyester diol (C) that is liquid at 50 ° C. is not particularly limited, but for example, a printing pattern from a conductive paste in the off-step Ratio of both in terms of nonvolatile content, polyester resin (B) solid at 50 ° C./polyester diol liquid at 50 ° C. (C) ) = 2/8 to 8/2, in particular 3/7 to 7/3.

  The proportion of the polyester resin (B) in the nonvolatile content is preferably 0.1 to 10% in terms of mass with respect to the total of the components, from the viewpoint of printability. In general, the content of the nonvolatile content of the solid resin component is preferably 2 to 20%, but this is a preferable range when printing using a gravure plate provided with only a concave portion consisting of a straight line. In the printing of bezel patterns typified by a shape in which two straight lines such as a substantially L shape or a substantially inverted L shape intersect or a shape in which a pair of them are combined, When the non-volatile content is outside the range, it is difficult to obtain excellent printability as in the present invention. When the content is 1% by mass or more, it becomes easy to form a conductive paste film having a good bezel pattern on the blanket, and the conductive paste film is easily transferred completely from the blanket to the substrate. When the content is 3% by mass or less, the paste viscosity becomes more appropriate, and the process of supplying the conductive paste to the gravure plate having the bezel-shaped conductive pattern becomes easy.

  When the material to be described later printed using the conductive paste of the present invention is, for example, polyethylene terephthalate (PET), coupled with the structural similarity to the polyester resin (B) and the polyester diol (C), to PET The adhesiveness of is improved.

(Blocked polyisocyanate compound)
Polyisocyanate compounds absorb moisture when isocyanato groups are exposed (free isocyanate groups) or coexist with organic compounds containing hydroxyl groups, so the urethanization reaction proceeds over time. It should be used immediately after preparation. Therefore, the operation | work which mixes two components generate | occur | produces in use.

  Therefore, in the present invention, a so-called block in which the free isocyanate group is sealed in the blocking agent in order to have a practical storage stability while being a one-part conductive paste and to react at a necessary time. A polyisocyanate compound is used. When selecting a thermosetting system, the storage stability of the conductive paste can be improved by using the polyester diol (C) and the blocked polyisocyanate (D), and the necessary time after preparation. It is possible to dissociate the blocking agent by heating and to react between the two.

  The blocked polyisocyanate compound (D) is liquid at 50 ° C., and the polyisocyanate compound produced after the blocking agent is dissociated by heating at 300 ° C. or less also has a boiling point exceeding 300 ° C. at normal pressure.

  The blocked polyisocyanate compound (D) can be easily prepared by reacting the polyisocyanate compound and the blocking agent by a known and usual method. Specifically, it is easily obtained by reacting a blocking agent with a polyisocyanate compound having a free isocyanate group until the intrinsic absorption spectrum based on the isocyanate group disappears while monitoring the infrared absorption spectrum. be able to.

  Examples of the polyisocyanate compound for obtaining the blocked polyisocyanate compound (D) include aromatic, aliphatic and alicyclic diisocyanates, di- or trimers obtained by modification of diisocyanate, and compounds containing terminal isocyanate groups. These may be used alone or in combination. Examples of the aromatic diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, diphenylmethane-2,4′-diisocyanate, dianisidine diisocyanate, and m-xylylene diene. Examples thereof include isocyanate and p-xylylene diisocyanate. Examples of the aliphatic diisocyanate include 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, and lysine diisocyanate. Etc. Examples of the alicyclic diisocyanate include isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 4,4′-dicyclohexylmethane diisocyanate, norbornane diisocyanate, and two or three amounts by modifying these diisocyanates. The body is mentioned. Examples of the modification method include biuretization and isocyanurate conversion. Or the above-mentioned di- or polyisocyanate compound and the terminal isocyanate group containing compound etc. which are obtained by making active hydrogen compounds, such as ethylene glycol, propylene glycol, trimethylol propane, polyester polyol, polyether polyol, polyamide, etc. react are mentioned.

  Examples of the blocking agent for obtaining the blocked polyisocyanate compound (D) include known and commonly used blocking agents such as phenol, methyl ethyl ketoxime, and sodium bisulfite. When the conductive pattern from the conductive paste of the present invention is provided on a heat resistant substrate such as glass, metal, silica or ceramics, any of these blocking agents can be used. When provided on a non-heat resistant substrate such as a PET film or a transparent ITO electrode film, it is preferable to use a blocked polyisocyanate compound in which the blocking agent dissociates at a lower temperature and the isocyanato group is liberated. In particular, when a PET film is used as a plastic film as a plastic film, the conductive paste contains a blocked polyisocyanate compound using a blocking agent such that the temperature when the isocyanato group is generated is 70 to 125 ° C. By doing so, a conductive pattern can be formed on the PET film without causing warpage or the like.

  Examples of such blocking agents that can be dissociated at a lower temperature include active methylene compounds and pyrazole compounds. Examples of active methylene compounds include Meldrum's acid, dialkyl malonate, alkyl acetoacetate, 2-acetoacetoxyethyl methacrylate, acetylacetone, ethyl cyanoacetate, and the like. Examples of pyrazole compounds include pyrazole, 3,5-dimethylpyrazole, 3- Examples include methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole. Of these, diethyl malonate, 3,5-dimethylpyrazole and the like are preferable.

  Commercially available blocked polyisocyanate compounds include Duranate (registered trademark) MF-K60B (manufactured by Asahi Kasei Chemicals Co., Ltd.) and Desmodur (registered trademark) BL-3475 (Suika Bayer) when the blocking agent is an active methylene compound. On the other hand, in the case where the blocking agent is a pyrazole compound, TRIXENE BI-7982 (manufactured by Baxenden) is used, and in the mixed type of active methylene compound and pyrazole compound, TRIXENE BI-7992 (manufactured by Baxenden) is mentioned.

  The conductive paste of the present invention that develops conductivity by firing is a thermosetting as a curing system for generating a urethane bond from the polyester diol (C) and the blocked polyisocyanate compound (D). It is preferred to select a system. The conductive metal particles (A) themselves have almost no light transmittance with respect to the active energy rays. Therefore, even if the paste containing the conductive metal particles (A) and the components (B) to (D) is formed into a film, the active energy rays do not reach the deep part in the film thickness direction, and the surface is cured. However, it is difficult to sufficiently cure to the deep part of the film. On the other hand, in the case of curing with heat, energy necessary for curing reaches a deep portion in the film thickness direction.

  The thermosetting conductive paste of the present invention comprises a combination of a polyester diol (C) that is a main agent that is not cured by itself and a blocked polyisocyanate compound (D) that produces a polyisocyanate compound that is a curing agent. The polyester resin (B) that substantially does not expect a reaction with the component (C) is contained. Each of the main agent and the curing agent is selected so as to be cured only by heating without reacting at room temperature even when both are mixed.

  When the polyester resin (B) used in the present invention is a polyester resin obtained using an aromatic divalent carboxylic acid or a derivative thereof, the dispersibility of the conductive metal particles (A) is excellent, and more It can be contained in the paste, and as a result, it is possible to further increase the conductivity, and it is preferable because it is excellent in adhesion to a printing material, particularly a PET film, even if it is not involved in curing. This adhesion can enhance the flexibility of an electric / electronic component provided with a conductive circuit when the printed material on which the conductive pattern is to be formed is a flexible non-heat resistant material, particularly a PET film. This is extremely advantageous in that high integration is possible.

  In thermosetting conductive pastes comprising a combination of polyester diol (C) and an isocyanate curing agent such as blocked polyisocyanate compound (D) as essential components, the polyisocyanate compound excluding the blocking agent in terms of mass It is more preferable that the non-volatile content of the polyester diol (C) is 20 to 200 parts per 100 parts of the non-volatile content in terms of excellent printability.

  The blocked polyisocyanate compound (D) used in the present invention can be used in combination with a curing catalyst if necessary. The curing catalyst is not particularly limited, but is preferably an organic ammonium salt or an organic amidine salt. Specifically, tetraalkylammonium halides, tetraalkylammonium hydroxides, tetraalkylammonium organic acid salts and the like are used for organic ammonium salts, and 1,8-diazabicyclo [5.4.0] undecene-7 ( DBU), 1,5-diazabicyclo [4.3.0] nonene-5 (hereinafter DBN) phenol salt, octylate, oleate, p-toluenesulfonate, formate, etc. it can. Among them, it is preferable to use DBU-phenol salt, DBU-octylate, DBN-octylate and the like. Commercially available products include TOYOCAT-TR20 (manufactured by Tosoh Corporation) for organic ammonium salts, U-CAT SA1, U-CAT SA102, U-CAT SA106, U-CAT SA506, U-CAT SA603, U-CAT for organic amidine salts. SA1102 (manufactured by San-Apro) can be mentioned. The organic ammonium salt or organic amidine salt not only acts as a blocking agent dissociation catalyst for the blocked polyisocyanate compound (D) but also acts as a ring-opening catalyst for the epoxy group when a polyfunctional epoxy compound is further used in combination. To do.

  The reaction catalyst of the blocked polyisocyanate compound (D) is 3 to 30 parts per 100 parts of the blocked polyisocyanate compound (D) in terms of mass, such as conductivity and solvent resistance finally obtained. This is preferable from the viewpoint of improving the performance of the conductive pattern.

  In the conductive paste of the present invention, the ratio of the conductive metal particles (A), the polyester resin (B), the polyester diol (C), and the polyisocyanate compound in the blocked polyisocyanate compound (D) is particularly limited. Although it is not a thing, in mass conversion of the non-volatile content, the mass ratio R of both when the total usage amount of the said thing (B) to (D) is set to R and the usage-amount of the said electroconductive metal particle (A) is set to P. / P is preferably adjusted to 0.07 to 0.15 from the viewpoint of the conductivity of the resulting conductive pattern.

  Of course, in the curing system of the conductive paste of the present invention, considering that only the active hydrogen atoms and all the isocyanate groups of the blocked polyisocyanate compound (D) contained in the raw materials used are consumed, The amount of non-volatile components used in each raw material may be selected so that they are stoichiometrically equal, but it is included in the raw material in consideration of various physical properties of the cured pattern obtained from the conductive paste. In many cases, the isocyanate group after the blocked polyisocyanate compound (D) dissociates more than the active hydrogen atom.

  The conductive paste of the present invention includes various raw materials (third component) other than the polyester resin (B) that is solid at 50 ° C., the polyester diol (C) that is liquid at 50 ° C., and the blocked polyisocyanate compound (D). Can be further added if necessary. Such a third component includes, among others, a hydrogenated ketone-formaldehyde condensate, a hydroxyl group-containing vinyl chloride-vinyl acetate copolymer, a hydroxyl group-containing styrene resin, a hydroxyl group-containing acrylic resin, and a hydroxyl group-containing polyvinyl acetal. A thermoplastic resin containing at least one hydroxyl group selected from the group can be used. Polyvinyl chloride and copolymers of vinyl chloride and other unsaturated double bond-containing monomers, (meth) acrylic acid ester homopolymers and (meth) acrylic acid esters and other unsaturated double bond-containing monomers Copolymer of polystyrene, styrene monomer and other unsaturated double bond-containing monomer, ketone-formaldehyde condensate and its hydrogenated product, polyfunctional epoxy resin, polyvinyl acetal, polyurethane, etc. These may be used alone or in combination of one or more selected from these.

  When the printing material is, for example, polyethylene terephthalate (PET), this third component has good adhesion to its own PET, such as a ketone-formaldehyde condensate or its hydrogenated product, vinyl chloride-acetic acid. A thermoplastic resin that is solid at 50 ° C. selected from the group consisting of a vinyl copolymer and polyvinyl acetal is preferably used. Such a ketone-formaldehyde condensate and its hydrogenated product are Evonik Degussa Japan Co., Ltd. TEGO (registered trademark) VariPlus series (SK, AP, etc.), and polyester is Byron (registered trademark) manufactured by Toyobo Co., Ltd. Series (Byron 200, etc.) is used as the vinyl chloride-vinyl acetate copolymer, and Solvain (registered trademark) series (Solvine AL, etc.) manufactured by Nissin Chemical Industry Oil Co., Ltd. is used as the polyvinyl acetal. A company-made ESREC (registered trademark) series (such as ESREC KS-10) may be mentioned.

  Examples of such a polyfunctional epoxy compound include 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, trimethylolpropane diglycidyl ether, 3 ′, 4′-epoxycyclohexylmethyl-3,4- Epoxycyclohexanecarboxylate, trimethylolpropane triglycidyl ether, tris (hydroxyphenyl) methane triglycidyl ether, etc., as the polymer polyol compound, for example, known and commonly used polyester polyol having a molecular weight of 800 or more, polyether polyol, polycarbonate polyol, Examples of oxetane compounds such as polycaprolactone polyol include 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane. Etc.

  As a curing agent (curing catalyst) for the polyfunctional epoxy compound, known and commonly used acid anhydrides, amines, imidazoles, phenol resins and the like can be used as necessary.

  Of course, when using a component containing a hydroxyl group as the third component, not only the hydroxyl value of the polyester diol (C) but also the hydroxyl value derived from the third component is taken into consideration. It is possible to match the total hydroxyl value of these and the isocyanate equivalent of the polyisocyanate compound generated from the blocked polyisocyanate compound (D), from the viewpoint of adhesion of the conductive pattern to the printing material and heat resistance. To preferred.

(Organic solvent having a boiling point of 170 to 300 ° C. at normal pressure not having reactivity with (A) to (D))
The polyester resin (B), polyester diol (C), and blocked polyisocyanate compound (D) used in the present invention are usually dissolved in a solvent and conductive metal so as to be suitable for various printing methods, for example. It is necessary to disperse the particles (A) in the mixture and form a paste, and then apply or print a fine line pattern of the conductive paste on the printed material. Therefore, in selecting the main agent and the curing agent constituting the thermosetting conductive paste, it is preferable to consider solubility in a solvent.

  From such a point of view, an organic solvent (E) having a boiling point of 170 to 300 ° C. at normal pressure that is not reactive with the (A) to (D) is used as the solvent. As the organic solvent (E), any conventional organic solvent that satisfies the above can be used. Examples of such organic solvents include tripropylene glycol-n-butyl ether, diethylene glycol monobutyl ether, tripropylene glycol methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol dimethyl ether, dipropylene glycol methyl ether acetate. Ethylene glycol monohexyl ether, dipropylene glycol methyl ether, propylene glycol diacetate, 1,4-butanediol divinyl ether, 3-methoxy-3-methylbutanol, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, terpineol, etc. Can be mentioned. These organic solvents (E) may be used individually by 1 type, or may use 2 or more types together.

  The content of the organic solvent (E) in the conductive paste of the present invention is not particularly limited as long as the above effect is obtained in the gravure offset printing method, but is preferably 5 to 30% by mass, Among these, 7 to 20% by mass is more preferable. Within this range, the paste viscosity becomes more appropriate, and in gravure offset printing, it is possible to form higher-definition printing patterns without causing pinhole defects at the corners of the image lines or at the intersections of the matrix. it can.

  When the conductive paste of the present invention is used to form a bezel pattern, the bezel pattern is hidden in the housing of a smartphone or a tablet computer, for example, but is not anxious, but is used to form a mesh pattern. In order to suppress the light reflection and glare caused by the conductive metal particles (A) contained in the pattern, the pattern is exposed through the display screen without being hidden in the casing. In addition, it is preferable to use a black pigment in combination. As such a black pigment, an inorganic black pigment such as carbon black or titanium black, or a black pigment obtained by mixing various organic pigments of three colors such as perylene black and YMC can be used.

  In the conductive paste of the present invention, various additives such as a dispersant, an antifoaming agent, a release agent, a leveling agent, and a plasticizer can be appropriately blended as appropriate in addition to the components described above.

  The conductive paste of the present invention can be applied to various printing methods such as a screen printing method, but is applied to a known and commonly used printing method that can be applied to printing with a fine pattern with a smaller line width. As a result, it is possible to form a fine wiring pattern (conductive pattern) superior to that of the prior art.

  In the gravure offset printing method suitably applied in the present invention, a gravure plate in which a recess corresponding to a desired printing pattern is formed, a doctor for filling a recess in the gravure plate, and a blanket whose surface is made of, for example, silicone rubber And are used. This gravure plate is provided with a groove having a recess corresponding to a pattern filled with a conductive paste. The conductive paste is transferred to the blanket from the concave portion which is a groove of the gravure plate. The printed material is supplied so as to face the blanket, the two are pressed against each other, and a pattern corresponding to the fine wiring pattern on the blanket is printed on the printed material, thereby forming a printed pattern. This printed pattern becomes a fine wiring pattern (conductive pattern) having conductivity by firing.

  That is, the gravure offset printing process is roughly divided into a doctoring process for filling a concave portion, which is a groove of a gravure plate, with a conductive paste, and an off process for transferring the conductive paste filled in the concave portion to the surface of the blanket. And a setting step of transferring the conductive paste transferred to the blanket to the substrate. According to this printing method, the shape of the print pattern can be freely set according to the shape of the recess, and the transfer rate of the conductive paste from the blanket to the substrate is high, so the print pattern corresponding to the fine wiring pattern can be accurately obtained. It is possible to form.

  In the gravure offset printing method, known intaglio plates, intaglio plates formed by exposing, developing, and washing a photosensitive resin on a glass plate, glass plates, metal plates, and intaglio plates formed by chemical etching and laser etching can be used. .

  In addition, as the gravure plate, a plate having a concave portion corresponding to a groove corresponding to various patterns having a known and common line width and depth can be used. It is preferable to use a gravure plate having a concave portion having a line width of 10 to 50 μm and a depth of 5 to 20 μm corresponding to various patterns in that excellent linearity can be secured and problems such as disconnection are not observed.

  In the gravure offset printing method, using a sheet to be printed, a flat plate as a gravure plate, and a cylindrical blanket as a blanket, the blanket is pressed against the substrate to print various patterns on the blanket. You may make it transfer-print on a to-be-printed material, and use the long to-be-printed material wound in roll shape, a cylindrical plate as a gravure plate, a cylindrical blanket as a blanket, and a cylindrical impression cylinder, respectively. Then, the blanket may be pressed against the printing material, and various patterns on the blanket may be continuously transferred and printed on the printing material.

  In addition, in the off process of transferring the conductive paste filled in the recesses to the surface of the blanket, the organic solvent (E) contained in the conductive paste is absorbed by the blanket, and the non-volatile content is further increased. It is transferred to the substrate in the process. Therefore, by repeating the printing cycle, the organic solvent (E) in the conductive paste accumulates in the blanket for each printing. Since the volume of the organic solvent (E) that can be absorbed by the blanket is naturally limited, if this limit is exceeded, proper transfer may not be performed on the printed material in the setting process, which may cause problems such as disordered printing patterns. . Therefore, when many printing is performed using one blanket, it is preferable to include a step of drying the blanket that has absorbed the organic solvent (E) after printing on the printing material. This drying process may be performed every printing cycle, or may be performed every 5 to 20 printing cycles at intervals.

  In the gravure offset printing method, a blanket is used. Examples of the blanket include a sheet having a layer structure such as a silicone rubber layer, a PET layer, and a sponge layer. Usually, it is used in a state of being wound around a rigid cylinder called a blanket cylinder.

  In the formation of a conductive pattern from a conductive paste, when the above gravure offset printing method is employed, the blanket is required to have transferability from an intaglio and transferability to a substrate. In order to obtain sufficient transferability to the printing material, it is necessary to absorb the liquid component in the conductive paste at a certain ratio on the blanket surface. Insufficient absorption tends to cause delamination of the conductive paste layer during transfer to the substrate, and conversely if absorbed over a certain percentage, the conductive paste dries on the blanket surface, resulting in poor transfer to the substrate It is easy to cause.

  The conductive paste of the present invention can form a printing pattern by applying or printing on any substrate such as a plastic film, a ceramic film, a silicon wafer, glass or a metal plate by any method. it can. However, the true value of the conductive paste of the present invention can be fully demonstrated when a PET film that cannot be exposed to high temperatures as a substrate to be printed when obtaining a conductive pattern or an ITO film using it as a support. Such a transparent conductive film.

  In preparing the conductive paste of the present invention, if the substrate to be printed is inferior in heat resistance, such as a plastic film, the conductive metal particles have a temperature higher than the decomposition temperature of the paste film containing the polyester resin and the polyurethane resin. It is preferable not to include an inorganic binder such as glass frit having a function of melting the conductive metal particles (A) to the printing material by melting below the melting point of (A). In the conductive paste of the present invention, the conductive metal is exclusively based on the polyester resin (B) and the polyurethane resin generated from the polyisocyanate compound generated from the polyester diol (C) and the blocked polyisocyanate compound (D). It is intended to fix the particles (A) to the printing material, and by containing this inorganic binder, the content of the conductive metal particles (A) itself has to be lowered, and excellent based thereon. In addition, it is not preferable that the electrical conductivity becomes difficult to achieve and the adherence to the printing material decreases.

  A fine wiring pattern having conductivity can be obtained by firing a printed pattern corresponding to a fine wiring pattern including patterns of various shapes formed on a substrate in the gravure offset printing described above. In this firing, the removal of the organic solvent (E) contained in the paste and the occurrence of a curing reaction between the polyester diol (C) and the polyisocyanate compound resulting from the blocked polyisocyanate compound (C) are performed. These may be performed in order or simultaneously.

  In the conductive paste of the present invention, in order to cause a curing reaction, heating by a heat source, irradiation with a xenon flash lamp, irradiation with ultra high frequency waves, irradiation with near infrared rays, irradiation with far infrared rays, etc. Can be adopted. However, as described above, in the case of using a PET film that cannot be exposed to high temperatures as a substrate to be printed or a transparent conductive film such as an ITO film using the PET film as a support, the curing reaction described above is 150. It is preferable to select a paste raw material so as to occur at a temperature of ℃ or lower, and to perform baking at a temperature of 150 ℃ or lower, particularly 100 to 140 ℃.

  The conductive paste of the present invention contains an organic solvent (E), but the paste is thinned in the doctoring process, and volatilization proceeds from the surface even if it is less than the boiling point. In the process, since the blanket further absorbs the organic solvent (D) from the printing pattern itself transferred from the gravure plate, the organic solvent (E) in the printing pattern transferred from the blanket onto the substrate in the setting process. Compared with the paste before a doctoring process, the content rate is reduced significantly. Therefore, the organic solvent (E) can be removed without heating to the boiling point or higher of the organic solvent (E) contained in the actually used conductive paste.

  Thus, the printing pattern provided on the printing material using the thermosetting conductive paste suitable for the present invention becomes, for example, a cured film by heating at 100 to 140 ° C. for 30 to 5 minutes, and becomes a conductive pattern. Expresses conductivity.

  Thus, according to the conductive paste of the present invention, for example, not only a thin line having a line width of 50 μm or less, but also an advanced printing technique with a narrower line width is required, and the degree of difficulty is 35 μm or less. It is also possible to cope with the formation of a conductive pattern having a very fine line width of 35 μm.

  As described above, since the conductive pattern from the preferred conductive paste of the present invention can be formed at a lower temperature and in a shorter time than before, the preferred conductive paste of the present invention is characterized by the ceramic film, glass or metal plate. This is particularly prominent when a conductive pattern is formed on a non-heat-resistant printed material that has a lower heat resistance and is more likely to be thermally deformed than such a highly heat-resistant printed material. Thus, the conductive pattern in which the cured film of the preferred conductive paste of the present invention is formed on the non-heat-resistant printed material is preferably used as a conductive circuit formed on the non-heat-resistant printed material. it can.

  In this way, various printed materials provided with conductive fine wiring patterns including patterns of various shapes formed by the gravure offset printing method using the conductive paste of the present invention are used as conductive circuits as needed. Further, by performing wiring or the like, various electric parts and electronic parts can be obtained. The conductive fine wiring pattern obtained based on the conductive paste of the present invention is excellent in adhesion to a transparent conductive film such as a transparent ITO electrode.

  With the conductive paste of the present invention, the fine wiring pattern formed on the printed material has, for example, an electrode part and a wiring part as a shape in plan view, and is formed along the edge of the display area of the touch panel. The so-called bezel pattern 1 can be mentioned.

  The bezel pattern 1 is an aggregate of thin lines connected to, for example, a transparent electrode. For example, as shown in FIG. 1, the first thin line pattern 2 extending in a predetermined direction and the first thin line pattern 2 are substantially orthogonal to each other. It has a pair of substantially L-shaped wiring patterns 4, 4 composed of a second fine line pattern 3 extending from one end of the first fine line pattern 2 in the direction. An electrode pattern 5 is formed by a plurality of fine lines extending on the opposite side of the first fine line pattern 2 at the tip of the second fine line pattern 3, and a pair of substantially L-shaped wiring patterns 4, 4 are The electrode patterns 5 and 5 are arranged so as to face each other at a predetermined interval, and the first thin line patterns 2 and 2 are arranged substantially parallel to each other. The line widths of the first fine line pattern 2 and the second fine line pattern 3 can be set to, for example, 10 μm to 100 μm. The electrode pattern 5 can be formed in a substantially rectangular region having a width of about 200 μm and a length of about 2000 μm, for example. In FIG. 1, when printing is performed in the vertical direction, the first fine line patterns 2 and 2 become fine lines in the Machine Direction (MD) direction, while the second fine line patterns 3 and 3 in the direction orthogonal to the first fine line patterns 3 and 3 , A thin line in the direction of Transverse Direction (TD).

  The conductive paste of the present invention is not only a bezel pattern formed by connecting two or more linear recesses, such as a substantially L shape, a substantially inverted L shape, a combination thereof, or a substantially B shape, It can also be applied to obtain a conventional linear pattern.

  Examples of the shape pattern in plan view other than the bezel pattern described above include a mesh pattern. Examples of the mesh pattern include a circular lattice, a triangular lattice, a tetragonal lattice, a rhombus lattice, and a hexagonal (honeycomb) lattice in a plane. What is necessary is just to adjust the magnitude | size of an aperture ratio as needed.

  The periodic mesh pattern may interfere with the periodic arrangement of pixels of the image display panel to cause moire (striped pattern). Specifically, when the randomness of the mesh arrangement of the mesh pattern is further increased, the moire elimination effect is improved, but instead, the unevenness in density tends to be conspicuous in the in-plane luminance distribution of the image display panel. Conversely, it is known that when the periodicity of the mesh arrangement of the mesh pattern is further increased, the shading unevenness is reduced, but the moire tends to be conspicuous.

In order to prevent both moiré and shading unevenness from occurring, as a mesh pattern, for example, as disclosed in JP2013-207038A, a main cutting having a cross section parallel to a plane perpendicular to the extending direction of the mesh The width Wt of the mesh at the height H / 4 on the surface is Wt <W4 with respect to the wrinkle width W4 at the level surface that is the surface of the substrate on which the mesh is provided, and the mesh is configured. The mesh pattern which is a shape in plan view when observed from the normal direction standing on the surface of the substrate on which the conductive ridge portion is formed is between the two branch points. It is composed of a number of boundary line segments L that extend to define the open area,
(A) The average value N of the number of boundary line segments extending from one branch point is 3.0 ≦ N <4.0.
(B) The shape of the opening area includes two or more kinds of polygons selected from a pentagon, a hexagon, and a heptagon, and the number of opening areas included in the mesh pattern is a hexagonal opening area. It is the most.
(C) The polygons constituting the mesh pattern are not constant in shape with the same number of sides.
Satisfy the three conditions, and
(D) It is preferable to use a mesh pattern (provisionally called a random lattice) including a region where there is no direction having periodicity in the arrangement of the opening regions.

  With the conductive paste of the present invention, two or more optimal conductive pastes having different properties are prepared by forming a simple linear pattern and a complicated pattern such as an intersection of them, and printing the paste. There is no need to use different types of patterns according to the complexity of the power pattern, and one conductive paste of the present invention forms a complicated bezel pattern and other simple linear patterns at a time with one printing. Became possible.

  Examples of the final product include a touch panel extraction electrode, a display extraction electrode, electronic paper, a solar battery, and other wiring products.

  Hereinafter, the present invention will be described using examples. In the examples, the term “part” simply means “part by mass”. Each measurement item followed the following method.

Molecular weight
The number average molecular weight in terms of polystyrene was measured by GPC.

Acid value (mgKOH / g)
Depending on the hydroxyl value of the sample, about 1 g or 5 g was precisely weighed and dissolved in 20 ml of tetrahydrofuran. Subsequently, it titrated with 0.1N potassium hydroxide (ethanol solution). A phenolphthalein solution was used as an indicator.

Hydroxyl value (mgKOH / g)
Approximately 2 to 12 g is precisely weighed according to the hydroxyl value of the sample, and exactly 25 ml of acetylating agent (mixed with acetic anhydride / pyridine = 1/19 (volume ratio)) is added and refluxed at 130 ° C. for 1 hour. Then, about 10 mL of ion exchange water was added and cooled to room temperature. Phenolphthalein was added as an indicator and titrated with 0.1N potassium hydroxide ethanol solution. A blank test was performed at the same time. The obtained value was corrected using the acid value and blank value obtained above to determine the hydroxyl value.

Synthesis example 1 (polyester resin a)
In a four-necked flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectifying tube, and water separator, 123.3 parts of dimethyl terephthalate, 29.0 parts of dimethyl isophthalate, 114.1 parts of sebacic acid, 3 -Rectification was performed by charging 55.0 parts of methyl-1,5-pentanediol (3MPD), 49.9 parts of neopentyl glycol (NPG), 28.8 parts of ethylene glycol (EG), and 0.079 parts of tetrabutyl titanate. The tube top temperature was raised to 180 ° C. over 2 hours so that the temperature did not exceed 55 ° C., and then held for 1 hour for transesterification. Next, the water separator was filled with xylene, (15 parts of xylene / 1000 parts of monomer) was added to the reaction vessel, and the temperature was raised to 240 ° C. over 3 hours. After the esterification reaction for 3 hours, 1 mmHg The pressure was gradually reduced to below, and polycondensation was carried out at 240 ° C. until the acid value reached 2 mgKOH / g or less.
The composition of the obtained polyester resin was terephthalic acid / isophthalic acid / sebacic acid // 3MPD / NPG / EG = 49/11/40 // 34/33/33 (molar ratio), number average molecular weight 28,000, acid The value was 2 mgKOH / g, and the hydroxyl value was 2 mgKOH / g.
This polyester resin a is 40 mol% of aliphatic dicarboxylic acid occupying the total (total dicarboxylic acid) of aromatic dicarboxylic acid and aliphatic dicarboxylic acid as 100 mol%, and the blocked polyisocyanate compound described later The polyisocyanate compound originated from has substantially no active hydrogen atom capable of reacting with the isocyanato group. This polyester resin a had a number average molecular weight of about 35,000 and was solid at a temperature of 50 ° C.

Synthesis example 2 (polyester resin b)
In a four-necked flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, and water separator, 136.5.3 parts of dimethyl terephthalate, 29.1 parts of dimethyl isophthalate, 100.2 parts of sebacic acid , 3-methyl-1,5-pentanediol (3MPD) 55.2 parts, neopentyl glycol (NPG) 50.1 parts, ethylene glycol (EG) 28.9 parts, tetrabutyl titanate 0.079 parts, After raising the temperature of the upper part of the rectification tube to 180 ° C. over 2 hours so as not to exceed 55 ° C., the ester exchange was carried out while maintaining for 1 hour. Next, the water separator was filled with xylene, (15 parts of xylene / 1000 parts of monomer) was added to the reaction vessel, and the temperature was raised to 240 ° C. over 3 hours. After the esterification reaction for 3 hours, 1 mmHg The pressure was gradually reduced to below, and polycondensation was carried out at 240 ° C. until the acid value reached 2 mgKOH / g or less.
The composition of the obtained polyester resin was terephthalic acid / isophthalic acid / sebacic acid // 3MPD / NPG / EG = 54/11/35 // 34/33/33 (molar ratio), number average molecular weight 28,000, acid The value was 2 mgKOH / g, and the hydroxyl value was 2 mgKOH / g.
This polyester resin b is 35 mol% of aliphatic dicarboxylic acid when the total (total dicarboxylic acid) of aromatic dicarboxylic acid and aliphatic dicarboxylic acid is 100 mol%, and is a blocked polyisocyanate compound described later. The polyisocyanate compound originated from has substantially no active hydrogen atom capable of reacting with the isocyanato group. The polyester resin b had a number average molecular weight of about 35,000 and was solid at a temperature of 50 ° C.

Synthesis example 3 (polyester resin c)
The charged dicarboxylic acid and diol were 110.1 parts of dimethyl terephthalate, 28.9 parts of dimethyl isophthalate, 127.8 parts of sebacic acid, 54.8 parts of 3-methyl-1,5-pentanediol (3MPD), neo A polyester resin b was obtained in the same manner as in Synthesis Example 1 except that the content was changed to 49.7 parts of pentyl glycol (NPG) and 28.7 parts of ethylene glycol (EG).
The composition of the obtained polyester resin was terephthalic acid / isophthalic acid / sebacic acid // 3MPD / NPG / EG = 11/44/45 // 34/33/33 (molar ratio), number average molecular weight 28,000, acid The value was 2 mgKOH / g, and the hydroxyl value was 2 mgKOH / g.
This polyester resin b is 45 mol% of aliphatic dicarboxylic acid occupying the total (total dicarboxylic acid) of aromatic dicarboxylic acid and aliphatic dicarboxylic acid as 100 mol%, and is a blocked polyisocyanate compound described later The polyisocyanate compound originated from has substantially no active hydrogen atom capable of reacting with the isocyanato group. This polyester resin had a number average molecular weight of about 35,000 and was solid at a temperature of 50 ° C.

Comparative Synthesis Example 1 (Polyester resin d)
The charged dicarboxylic acid and diol were 137.0 parts of dimethyl terephthalate, 42.0 parts of dimethyl isophthalate, 86.2 parts of sebacic acid, 55.4 parts of 3-methyl-1,5-pentanediol (3MPD), neo A polyester resin c was obtained in the same manner as in Synthesis Example 1 except that 50.3 parts of pentyl glycol (NPG) and 29.0 parts of ethylene glycol (EG) were used.
The composition of the obtained polyester resin was terephthalic acid / isophthalic acid / sebacic acid // 3MPD / NPG / EG = 16/54/30 // 34/33/33 (molar ratio), and the number average molecular weight was 28,000. It was.
This polyester resin d is 30 mol% of aliphatic dicarboxylic acid when the total of aromatic dicarboxylic acid and aliphatic dicarboxylic acid (total dicarboxylic acid) is 100 mol%, and the blocked polyisocyanate compound described later It has sufficient active hydrogen atoms that can react with the isocyanato group of the polyisocyanate compound originating from 1. Moreover, this polyester resin was in the range of a number average molecular weight of 20,000 to 40,000, and was solid at a temperature of 50 ° C.

Synthesis example 4 (polyester diol)
In a four-necked flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectifying tube, and water separator, 185.8 parts of adipic acid (AdA), 24.4 parts of glutaric anhydride, 3-methyl-1, First, 173.9 parts of 5-pentanediol (3MPD) and 15.8 parts of 1,4-butanediol (BG) are charged, and it takes 3 hours to 160 ° C. so that the upper temperature of the rectifying tube does not exceed 100 ° C. After the increase, dehydration condensation reaction was performed until the acid value reached 2.
The composition of the obtained polyester diol was adipic acid / glutaric acid / 3MPD / BG = 86/14 // 89/11 (molar ratio), number average molecular weight 2,000, and hydroxyl value 54 mgKOH / g.
This polyester diol is 100 mol% of the aliphatic dicarboxylic acid when the total (total dicarboxylic acid) of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid is 100 mol%. It had sufficient active hydrogen atoms capable of reacting with the isocyanato group of the polyisocyanate compound. The polyester diol had a number average molecular weight of 10,000 or less and was liquid at a temperature of 50 ° C.

Example 1 (conductive paste for printing bezel pattern)
74 parts by mass of spherical silver powder having a median particle size (D50) of 0.2 to 0.5 μm, a mass of the polyester resin a (nonvolatile content) / the polyester polyol (nonvolatile content) 6/4 in a mass ratio, and the polyester The polyester resin a (nonvolatile component) is obtained by using the hydroxyl value of the polyol and the mass at which the isocyanate equivalent of VAXENDEN TRIXENE BI 7982 (the blocked polyisocyanate compound whose blocking agent is 3,5-dimethylpyrazole) matches. / Mixing of terpineol solvent, butyl carbitol acetate, dipropylene glycol monomethyl ether, 1,4-butanediol vinyl ether so that the total of the above polyester polyol (non-volatile content) / TRIXENE BI 7982 (non-volatile content) is 10 parts by mass. Solvent (6 / .5 / 3 / 2.5) 16 parts with, and sufficiently kneaded them, to prepare a gravure offset printing conductive paste A.

Example 2 (same as above)
By using a mass at which the polyester resin a (non-volatile content) / the polyester polyol (non-volatile content) 4/6 in mass ratio, the hydroxyl value of the polyester polyol, and the isocyanate equivalent of TRIXENE BI 7982 coincide with each other. For gravure offset printing in the same manner as in Example 1 except that the total of the polyester resin a (nonvolatile content) / the polyester polyol (nonvolatile content) / TRIXENE BI 7982 (nonvolatile content) is 10 parts by mass. A conductive paste B was prepared.

Example 3 (same as above)
By using a mass at which the polyester resin b (non-volatile content) / the polyester polyol (non-volatile content) 4/6 in mass ratio, the hydroxyl value of the polyester polyol, and the isocyanato equivalent of TRIXENE BI 7982 are matched. For gravure offset printing in the same manner as in Example 1 except that the total of the polyester resin b (non-volatile content) / the polyester polyol (non-volatile content) / TRIXENE BI 7982 (non-volatile content) is 10 parts by mass. A conductive paste C was prepared.

Example 4 (same as above)
By using a mass at which the polyester resin c (non-volatile content) / the polyester polyol (non-volatile content) 4/6 in a mass ratio, a hydroxyl value of the polyester polyol, and a mass at which the isocyanate equivalent of TRIXENE BI 7982 matches. For gravure offset printing in the same manner as in Example 1 except that the total of the polyester resin c (non-volatile content) / the polyester polyol (non-volatile content) / TRIXENE BI 7982 (non-volatile content) is 10 parts by mass. A conductive paste D was prepared.

Comparative Example 1 (same as above)
74 parts by mass of spherical silver powder having a median particle size (D50) of 0.2 to 0.5 μm, and a mass by which the hydroxyl value of the polyester resin d (non-volatile content) and the isocyanato equivalent of TRIXENE BI 7982 coincide with each other. The total amount of the polyester resin d (nonvolatile content) / TRIXENE BI 7982 (nonvolatile content) is 10 parts by mass, terpineol solvent, butyl carbitol acetate, dipropylene glycol monomethyl ether, 1,4-butanediol. Using 16 parts of a mixed solvent of vinyl ether (10 / 0.5 / 3 / 2.5), these were sufficiently kneaded to prepare a conductive paste E for gravure offset printing.

(Printability)
Using each of the conductive pastes of Examples 1 to 3 and Comparative Example 1, gravure offset printing was performed by the following method to prepare conductive patterns including a bezel pattern. These evaluation results are shown in Table 1 below.

  After inking each conductive paste with a doctor blade on a flat plate-shaped intaglio plate made of glass provided with grooves corresponding to the bezel pattern of FIG. 1 having a groove line width of 30 μm and a groove depth of 10 μm, a silicone blanket The desired pattern was transferred onto the blanket by being pressed and brought into contact with a cylinder around which was wound. Thereafter, the coating film on the blanket is pressed and transferred onto the ITO film surface of a sheet-like transparent conductive film (thickness 250 μm), which is a flat plate-like printed material, and a printed pattern having a line width of about 30 μm is printed. It was created. A line corresponding to the TD direction of the printed bezel pattern having a width of about 30 μm (second thin line patterns 3 and 3 in FIG. 1) was observed with a microscope, and the fine line reproducibility was evaluated as after the first printing according to the following criteria. . Printing was repeated, and the printed material after 100 printings (100 sheets) was also evaluated in the same manner as described above after continuous printing. Every 5 printings (every 5 sheets), hot air was blown to the silicone blanket with a dryer, and after confirming that the organic solvent that had permeated the blanket was volatilized, the next printing was performed.

◎: Excellent linearity of the wire, no disconnection ○: Excellent linearity of the wire, no disconnection △: Inferior linearity of the wire, no disconnection ×: Inferior linearity of the wire, disconnection

(Volume resistivity)
Using an applicator, the conductive paste was applied onto the transparent conductive film (ITO film surface) so that the film thickness after baking was 4 μm and baked at 125 ° C. for 30 minutes. Using this baked coating film, it was measured by a four-terminal method with Loresta GP MCP-T610 (manufactured by Mitsubishi Chemical Corporation). Volume resistivity is a measure of conductivity.

○: 5 × 10 ⁻⁴ Ω · cm or less Δ: 5 to 10 × 10 ⁻⁴ Ω · cm
×: 10 × 10 ⁻⁴ Ω · cm or more

  As can be seen from the comparison of the evaluation results of Example 1 and Comparative Example 1, the conductive paste of Example 1 in which polyester diol and a polyester resin containing a sufficiently large chemical structure based on sebacic acid are combined is polyester diol. Compared to that of Comparative Example 1 using a polyester resin that contains only a small amount of a chemical structure based on sebacic acid, the printability at the time of continuous printing is excellent, and the conductivity of the conductive pattern is improved. It is clear that it is also excellent.

  In addition, as can be seen from the comparison of the evaluation results of Example 1 and Example 2, when the polyester resin and the polyester diol are fixed and the contents of both are changed, the conductivity of Example 2 containing more polyester diol. It is clear that the paste is excellent in fluidity and printability at the first printing as compared with that of Example 1 containing more polyester resin.

  Further, in comparison between Example 2 and Example 3, the conductive paste of Example 2 using a polyester resin containing more chemical structure based on sebacic acid has less chemical structure based on sebacic acid. It was more fluid and easier to handle than the conductive paste of Example 3 using the contained polyester resin.

Example 4 (conductive paste for mesh pattern printing)
Instead of 74 parts by mass of spherical silver powder having an average particle size (D50) of 0.2 to 0.5 μm, the same procedure as in Example 1 was carried out except that 72 parts by mass of spherical silver powder and 2 parts of carbon black (black pigment) were used. Thus, a conductive paste F for gravure offset printing was prepared.

  Using the conductive paste for mesh pattern printing of Example 4 above, instead of “a flat intaglio plate made of glass provided with a groove corresponding to a bezel pattern having a groove line width of 30 μm and a groove depth of 10 μm”. “A flat plate-shaped intaglio plate made of glass having grooves corresponding to the square lattice mesh pattern of FIG. 2 having a groove line width of 5 μm and a groove depth of 5 μm” was used. A printed pattern was prepared in the same manner as in Example 1 except that “PET film having an average thickness of 250 μm” was used in place of “,” and baked at 125 ° C. for 30 minutes.

According to microscopic observation, the silver fine wires constituting the tetragonal lattice mesh pattern were particularly excellent in linearity, and no broken portions were found. Moreover, the volume resistivity of the thin wire was 5 × 10 ⁻⁴ Ω · cm or less, and had excellent conductivity.

Example 5
In the same manner as in Example 4 above, a mesh pattern made of silver fine wires was formed on a PET film, and then the bezel pattern was formed with the conductive paste of Example 1 on the surface provided with the square lattice mesh pattern. Once formed, both patterns were fired simultaneously at 125 ° C. for 30 minutes.

  The mesh pattern fine wire containing carbon black and silver was less affected by light reflection and glare than the bezel pattern made of silver fine wire not containing carbon black. A cheaper silver and carbon black can be used to replace the ITO film, which is a transparent conductive film with a necessary pattern formed through multiple processes, using an expensive material such as indium tin oxide. Was also very flexible.

  In the above description, the bezel pattern and the mesh pattern are sequentially provided by the gravure offset printing method. However, the printing of the bezel pattern and the mesh pattern can be performed in either pattern first. If the intaglio is prepared, the bezel pattern and the mesh pattern can be simultaneously provided on a substrate (support) such as a PET film by the gravure offset printing method.

  The conductive paste of the present invention can be used, for example, to form various fine wiring patterns having conductivity such as a bezel pattern and a mesh pattern on various electric parts and electronic parts.

Claims (9)

Conductive metal particles (A), polyester resin (B) that is solid at 50 ° C., polyester diol (C) that is liquid at 50 ° C., blocked polyisocyanate compound (D), and (A) to (D) And an organic solvent (E) having a boiling point of 170 to 300 ° C. at normal pressure and no reactivity , and at least one of the polyester resin (B) and the polyester diol (C) has a methylene bond repeating unit. A conductive paste for printing a conductive pattern , characterized by using a polyester resin or a polyester diol containing a condensed structure derived from an aliphatic dicarboxylic acid of 6 to 8 . At least one of the polyester resin (B) and the polyester diol (C) is a polyester resin or polyester diol obtained by condensing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and a diol, and the aromatic dicarboxylic acid and the aliphatic diol. when the sum of the dicarboxylic acid and 100 mole%, the polyester resin obtained by using the above 33 mol% of an aliphatic dicarboxylic acid, or claim 1, wherein the conductive paste using the polyester diols. The conductive paste according to claim 1 or 2 , wherein the conductive metal particles (A) are conductive metal particles containing conductive metal particles having a median particle size (D50) of 0.1 to 0.7 µm. The conductive paste according to claim 1 or 2 , wherein a mass ratio of the polyester resin (B) that is solid at 50 ° C and the polyester diol (C) that is liquid at 50 ° C is 2/8 to 8/2. The conductive paste according to claim 1 or 2 , wherein the blocked polyisocyanate compound (D) is a blocked polyisocyanate in which the blocking agent is an active methylene compound and / or a pyrazole compound. Furthermore, the electrically conductive paste of Claim 1 or 2 containing a black pigment. A gravure plate provided with a recess including a pattern to be filled with paste, a doctor filling the recess of the gravure plate with a blanket, a blanket to which the paste is transferred from the recess of the gravure plate, and facing the blanket In the method for forming a conductive pattern by the gravure offset printing method, the substrate is supplied, and a pattern corresponding to the fine wiring pattern on the blanket is printed on the substrate, and then baked. A method for forming a conductive pattern, wherein the conductive paste according to any one of claims 1 to 6 is used. A gravure plate provided with a recess including a bezel pattern filled with paste, a doctor filling the recess of the gravure plate with a blanket, and a blanket from which the paste is transferred from the recess of the gravure plate, and facing the blanket In the method for forming a conductive pattern by a gravure offset printing method, the substrate is supplied with a print, a pattern corresponding to the fine wiring pattern on the blanket is printed on the substrate, and then fired. As a method for forming a conductive pattern, the conductive paste according to any one of claims 1 to 5 is used. A gravure plate provided with a concave portion including a mesh pattern, filled with a paste, a doctor filling the concave portion of the gravure plate with a paste, a blanket from which the paste is transferred from the concave portion of the gravure plate, and facing the blanket In the method of forming a conductive pattern by the gravure offset printing method, the printing material is supplied in the same manner, the pattern corresponding to the fine wiring pattern on the blanket is printed on the printing material, and then fired. A method for forming a conductive pattern, wherein the conductive paste according to claim 6 is used as the paste.

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