JPWO2015151892A1 - Photosensitive conductive paste, conductive thin film, electric circuit, and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems, and the main object of the present invention is to filter the photosensitive conductive paste so that coarse particles and foreign matters in the paste can be removed. Gives excellent fine pattern formability. Further, the present invention provides a photosensitive conductive paste that has excellent wet heat environment reliability, forms an excellent fine pattern, has excellent adhesion and durability to a substrate, and has excellent temporal stability. . A photosensitive organic binder (A), containing a conductive powder having an average particle diameter D50 of 5 μm or less, a photopolymerizable compound, a photopolymerization initiator, and an organic solvent, and having a grind gauge scratch of 10 μm or less. A photosensitive conductive paste, a conductive thin film, a conductive laminate, an electric circuit, and a touch panel formed using the conductive paste. [Selection figure] None

Description

  The present invention provides a conductive composition suitable for forming a fine pattern on various substrates, particularly on a transparent conductive film, and relates to various electric circuit boards and touch panels produced thereby.

  In recent years, various electronic components are required to be small and highly accurate, and in particular, a high density of conductor circuit patterns is strongly demanded.

  As a method for forming a conductor circuit pattern, a printing method by screen printing has been widely adopted, but there is a limit to the formation of a high-density pattern, and a line having a constant width is formed with a resolution of L / S = 50/50 μm or less. It was difficult to form.

On the other hand, Japanese Patent Application Laid-Open Nos. 2003-162921 (reference 1) and 2013-182800 (reference 2) propose a method for forming a high-density pattern using a photosensitive conductive paste. It is said that a practical pattern molded product can be obtained by blending a thermosetting resin such as an epoxy resin with a photosensitive resin and performing a thermosetting reaction at 80 to 300 ° C.
However, when a thermosetting resin such as an epoxy resin is blended with the conductive paste, it causes a foreign matter by gradually reacting with carboxyl groups in some of the photosensitive resins in the roll dispersion process during paste production. In addition, a smooth coating film could not be formed, and as a result, developability could be affected.
Furthermore, since the photosensitive conductive paste produced in the above process is not filtered, it is possible to avoid the possibility that the aggregates and coarse particles derived from the raw materials in addition to the foreign matters generated during the production described above remain during the production. As a result, they negatively affected the developability of the fine lines.
On the other hand, in order to form a line having a constant width with a resolution of L / S = 50/50 μm or less, it is required that the conductive powder used has a moderately small particle size and a uniform particle size. However, the conductive powder having a moderately small particle size distribution has a complicated manufacturing process, and the produced silver powder tends to be aggregated and difficult to disperse. For example, when the silver powder described in Patent Document 3 is applied to a photosensitive conductive paste as it is, projections are generated on the surface of the paste coating film due to coarse particles, etc., and light is scattered during photocuring, resulting in a fine fine film after development. The pattern could not be obtained. Patent Document 3 describes that, as a result of producing and evaluating a photosensitive paste, there was no residue or peeling, and that it was good as a paste for drawing thin wire, but what specifically was used as a photosensitive resin? There was no description and it was impossible to reproduce it.

JP 2003-162921 A JP2013-182800A JP 2008-1974 A

  The present invention has been made to solve such problems, and its main purpose is to remove coarse particles and foreign substances in the paste by paste filtration, thereby providing excellent fine pattern formability by development, The present invention provides a photosensitive conductive paste having excellent adhesion and durability to a base material and excellent in temporal stability.

The photosensitive electrically conductive paste of this invention consists of the following structures.
1. Containing a photosensitive organic binder (A), a conductive powder (B) having an average particle diameter D50 of 5 μm or less, a photopolymerizable compound (C), a photopolymerization initiator (D), and an organic solvent (E); A photosensitive conductive paste characterized in that a scratch on a grind gauge begins to occur at 10 μm or less.
2. The photosensitive organic binder (A) contains a photosensitive organic binder having an acid value of 500 to 4,000 eq / ton and a weight average molecular weight of 5,000 to 8,000. The photosensitive conductive paste as described in 1.
3. As the photosensitive organic binder (A), a (meth) acrylic copolymer obtained by adding an alicyclic epoxy (meth) acrylate to a part of the carboxyl group of a (meth) acrylic copolymer having a carboxyl group is used. 1. It is characterized by containing. ~ 2. The photosensitive electrically conductive paste in any one of.
4). 1 above. ~ 3. A conductive thin film formed from the photosensitive conductive paste according to any one of the above. 5. 3. The arithmetic average roughness of the conductive thin film is 0.40 μm or less. The conductive thin film according to 1.
6). 4. above. Or 5. An electric circuit comprising the conductive thin film described in 1.
7). 6. above. A touch panel comprising the electrical circuit described in 1 as a constituent member.
8). (1) A step of filtering photosensitive conductive paste with a filter having an opening of 30 μm or less,
(2) Next, a step of applying the photosensitive conductive paste on a substrate and drying at a temperature of 110 ° C. or lower,
(3) Next, a step of exposing a part of the applied photosensitive conductive paste,
(4) Next, developing the unexposed area,
(5) A step of drying an unexposed exposed portion at a temperature of 140 ° C. or lower. The method includes the steps (1) to (5) above. Or 5. The manufacturing method of the electroconductive thin film of description.

By using the photosensitive conductive paste of the present invention, it is possible to obtain a coating film with good smoothness of the coating film with few coarse particles and foreign matters, so that it has excellent fine pattern properties during alkali development. Further, the conductive paste is less likely to generate foreign matters during production, has high storage stability, and has high reliability.

It is the figure which showed the electroconductive thin film pattern after image development.

  The photosensitive conductive paste of the present invention can form a fine fine pattern by photolithography after forming a coating film on a substrate by using a photosensitive organic binder. The thin wire thus obtained has high conductivity and excellent adhesion to the substrate.

Hereinafter, embodiments of the photosensitive conductive paste of the present invention will be described in detail.

  The photosensitive conductive paste of the present invention comprises a photosensitive organic binder (A), a conductive powder (B) having an average particle diameter D50 of 5 μm or less, a photopolymerizable compound (C), a photopolymerization initiator (D), And an organic solvent (E), and scratches of a grind gauge begin to occur at 10 μm or less.

The photosensitive organic binder (A) used in the photosensitive conductive paste of the present invention refers to a polymer resin having a photoreactive (meth) acryloyl group in its molecule and a developable carboxyl group, Is not limited, but a (meth) acrylic copolymer in which an epoxy (meth) acrylate is added to a part of a pendant carboxyl group of a (meth) acrylic copolymer having a pendant carboxyl group in the main chain of the molecular chain ( It is preferable that

As the epoxy (meth) acrylate to be added to a part of the carboxyl group, alicyclic epoxy (meth) acrylate is preferable. Not only can photosensitivity be imparted by adding alicyclic epoxy (meth) acrylate, but by introducing an alicyclic structure, the glass transition temperature is high, there is no coloration, and solvent solubility is good. This is because a low-viscosity photocurable binder resin can be supplied. By introducing a pendant carboxyl group, it is possible to impart an acid value in an appropriate range described later to the photosensitive organic binder (A).
Specifically, as a copolymerization component of the (meth) acrylate monomer constituting the photosensitive organic binder (A), acrylic acid, methacrylic acid, carboxylic acid itaconic acid are used to introduce a carboxyl group for the purpose of imparting alkali solubility. , Crotonic acid, maleic acid, vinyl acetate and modified unsaturated monocarboxylic acids chain-extended between unsaturated groups and carboxylic acids, such as β-carboxyethyl (meth) acrylate, 2-acryloyloxyethyl succinic acid, Compounds such as 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, unsaturated monocarboxylic acids having an ester bond such as lactone modification, and modified unsaturated compounds having an ether bond are used.
As copolymerization components other than introducing the carboxylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (Meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) ) Acrylate, isodexyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, Bonyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, allyl (meth) acrylate, 1-naphthyl (meth) acrylate, glycidyl ( (Meth) acrylate, allyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, caprocactone modified 2-hydroxyethyl (meth) (Meth) acrylic acid esters having a hydroxyl group such as acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, isooctyl Oxydiethylene glycol (meth) acrylate, phenoxytriethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and other caprolactone-based (meth) acrylates to give flexibility (Brand name: Sartomer SR495 manufactured by Nippon Kayaku, Plaxel FA-1, Plaxel FA-2, Plaxel FA-2D, Plaxel FA-3, Plaxel FA-4, Plaxel FA-5, Plaxel FM-1, (Meth) acrylates such as Plaxel FM-2, Plaxel FM-2D, Plaxel FM-3, Plaxel FM-4, Plaxel FM-5 and the like may be used.
As the copolymerization component other than the acrylic monomer, all compounds having a carbon-carbon double bond can be used. Preferred monomers include styrene, p-methylstyrene, o-methylstyrene, m-methyl. Examples include styrene.
The (meth) acrylic copolymer can be polymerized using the above-mentioned compounds by a known polymerization method, for example, radical polymerization.
As the alicyclic epoxy (meth) acrylate added to a part of the carboxyl group of the carboxyl group-containing (meth) acrylate polymer polymerized using the above compound, 3,4-epoxycyclohexylmethyl (meta ) Acrylate is preferred.
As such a photosensitive organic binder (A), as a commercial product, Cyclomer P series manufactured by Daicel Ornex Co., Ltd. is preferable, (ACA) 200M, ACA 230AA, ACAZ250, ACAZ251, (ACA) Z300. , (ACA) Z320 and the like.
The above may be used singly or there is no problem even if two or more kinds are mixed.

  The photosensitive organic binder (A) used in the present invention has an acid value of 500 to 4,000 eq / ton, and more preferably 700 to 3,000 eq / ton. When the acid value is less than 500 eq / ton, the developability with alkali is insufficient, and it is difficult to form a fine pattern. On the other hand, when the acid value exceeds 4,000 eq / ton, the hydrophilicity becomes too high, and the adhesion with the substrate under wet heat is greatly reduced.

  Moreover, the photosensitive organic binder (A) used for the photosensitive electrically conductive paste of this invention is characterized by having a weight average molecular weight of 5,000-80,000. The range of the weight average molecular weight is preferably 6,000 to 50,000, more preferably 7,000 to 40,000. If the weight average molecular weight is less than 5,000, the coating obtained by photocrosslinking becomes brittle and the adhesion to the substrate is poor. Conversely, if the weight average molecular weight exceeds 80,000, the solution viscosity of the conductive paste Becomes too high, making it difficult to apply to a smooth substrate. If a large amount of an organic solvent is used in order to reduce the solution viscosity, the dispersibility of the conductive powder becomes non-uniform, and the conductivity of the formed fine wire decreases, which causes a problem.

The photosensitive organic binder (A) used in the conductive paste of the present invention may be used alone or may be further blended with one or more types of photosensitive organic binders. The reason for this is that when the photosensitive conductive paste of the present invention is used as a conductive coating film, heat resistance, water resistance, and adhesion to a substrate are important. Organic binder (A)
In the case of using only a single compound, the developability is extremely lowered, and a large amount of residue may be generated after development. Therefore, in order to improve alkali developability, fine developability can be obtained by blending a photosensitive organic binder (A ′) having a molecular weight lower than that of the photosensitive organic binder (A1) as a main polymer, if necessary. And the reliability of the cured coating film can be made compatible.
As a weight average molecular weight of a photosensitive organic binder (A '), it is preferable that it is 500-20000 smaller than a photosensitive organic binder (A1), More preferably, it is 1000-16000. When it is smaller than 500, the effect of improving developability is small, and when it is larger than 20000, tackiness may be expressed on the film surface. May be contaminated.
In addition, as the type of the above (A ′), from the viewpoint of compatibility with the binder (A), a part of the carboxyl group of the (meth) acrylic copolymer which is the same skeleton as (A) has an alicyclic It preferably has a structure to which a formula epoxy (meth) acrylate is added.

  The photosensitive organic binder (A) used in the present invention has an acid value of 500 to 4,000 eq / ton, and is further sensitive to side chains for the purpose of adjusting the photosensitivity or the characteristics of the cured coating film. It is possible to introduce an unsaturated double bond having a property. The method of introducing an unsaturated double bond is not particularly limited, but a method of reacting a compound having an unsaturated double bond and an epoxy group in the molecule with a carboxyl group in the organic binder (A) is simple. It is. As the compound containing an unsaturated double bond and an epoxy group in the molecule, glycidyl (meth) acrylate, allyl glycidyl ether and the like can be used.

Next, the conductive powder (B) used in the present invention can be used as long as it is a powder having conductivity, specifically, gold, silver, platinum, palladium, nickel, A simple substance such as copper, aluminum, tin, or iron, or an alloy thereof, tin oxide, indium oxide, or the like can be used. Among them, silver is preferable in the present invention, and silver-coated copper powder in which copper is coated with silver is used. There is no problem. As the shape of the conductive powder, known flaky (flaky), spherical, dendritic (dendritic), spherical primary particles described in JP-A-9-306240 are three-dimensionally formed. There are agglomerated shapes (aggregated silver powder) and the like, and any of them can be used. However, considering conductivity and light transmittance, spherical or a combination of spherical and aggregated silver powder is preferable.
Moreover, as an average particle diameter (D50) of the said electroconductive powder (B), it is preferable that an average particle diameter (D50) is 5 micrometers or less from a viewpoint that the fine wire shape after image development is favorable. By using a small conductive powder having a center diameter of 5 μm or less, the filtration becomes efficient and the improvement of productivity can be expected.
The lower limit is not particularly limited, but is preferably 80 nm or more because it tends to aggregate when the particle size is small and the particle size is small, and as a result, dispersion becomes difficult. If it is smaller than 80 nm, the cohesive force of the conductive powder increases, and the filtration efficiency is lowered during filtration, and it is not preferable from the viewpoint of cost.
When conductive powder with a center diameter larger than 5 μm is used, the filter is clogged, the production efficiency is significantly reduced, and the fine line developability deteriorates. As a result, the fine lines come into contact with each other, resulting in a short circuit. May be incurred.
The average particle diameter (D50) of the conductive powder (B) used in the present invention is more preferably 3 μm or less.

The conductive powder (B) used in the present invention may have a plate-like conductive silver powder. By adding the plate-like conductive silver powder, the plate-like silver powder is present in the gaps of the silver powder, so that the filling rate is increased and the conductivity is improved, and the mechanical strength of the coating film can be improved. Furthermore, in the anchor effect at the interface between the conductive coating and the base material, the contact resistance value can be improved, and in combination with other silver powder, the plate-like silver powder can fill the gap between other silver powders, The concealment property when applied to a coating film is improved.

  The content of the conductive powder (B) used in the present invention is preferably 200 to 2,000 parts by weight when the total amount of the photosensitive organic binder (A) is 100 parts by weight. 300-1500 are preferable. If the blending amount of the conductive powder (B) is less than 200 parts by weight, it may be difficult to obtain the desired conductivity. On the contrary, if it is used in excess of 2,000 parts by weight, the conductive powder In some cases, it is difficult to disperse the film, and uniform coating may be difficult. Such conductive powder (B) preferably contains at least silver powder having an average particle diameter D50 of 5 μm or less, and more preferably accounts for 50% by weight or more of the total conductive powder.

  As the photopolymerizable compound (C) used in the photosensitive conductive paste of the present invention, 2-ethylhexyl (meth) acrylate, butoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentanyl (meth) acrylate, Isobonyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, methoxyethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate , Neopentyl glycol di (meth) acrylate, propylene glycol di (meth) acrylate, bisphenol A di (meth) acrylate, bisphenol A-ethylene oxide addition Di (meth) acrylate, bisphenol A diglycidyl ether / (meth) acrylic acid adduct, trimethylolpropane tri (meth) acrylate, glycerin di (meth) acrylate, diglycerin ethylene oxide modified (meth) acrylate, trimethylolpro Pan-ethylene oxide adduct tri (meth) acrylate, trimethylolpropane polyglycidyl ether / (meth) acrylic acid adduct, pentaerythritol triacrylate, dipentaerythritol hydroxypenta (meth) acrylate, pentaerythritol tetra (meth) acrylate, etc. (Meth) acrylate monomers can be mentioned, but are not limited to these, and any compound having a known unsaturated double bond with photosensitivity can be used. These can be used alone or in admixture of two or more. Among these, it is preferable to use a polyfunctional photopolymerizable monomer in order to increase the crosslinking density. By including these photopolymerizable compounds (C), the crosslinking density can be improved, and the flexibility and hardness of the coating film can be adjusted by adjusting the distance between the crosslinking points in the photoreaction. it can. Moreover, it is preferable to have a hydroxyl group or a carboxyl group, which is a hydrophilic functional group, from the viewpoint of not affecting development.

In addition, the photoreactive compound alone may cause insufficient flexibility and insufficient substrate adhesion. To improve these, reactive oligomers (prepolymers having a high molecular weight and capable of imparting various functions). Polymer) may be blended. Examples of oligomers include urethane oligomers, polyether oligomers, epoxy oligomers, polyester oligomers, and acrylic oligomers.
More specifically, examples of the urethane-based oligomer include EBECRYL230, EBECRYL244, EBECRYL245, EBECRYL270, EBECRYL284, EBECRYL285, EBECRYL4858, EBECRYL210, EBECRYL210, and EBECRYL210, EBECRYL210 and EBECRYL210, manufactured by Daicel Ornex. -600, AT-600, UA-306H, Beam set 502H, Beam set 504H, Beam set 505A-6, Beam set 550B, Beam set 575, AKCROS, Actilane 200, Actilane 200TP20, Actilane 210TP30, Actilane 230HD30 manufactured by Arakawa Chemical Industries, Ltd. , A tilane250HD25, Actilane250TP25, Actilane270, Actilane280, Actilane290, Actilane165, Actilane167, Actilane170, Sartomer Co. of CN929, CN961E75, CN961H81, CN962, CN963, CN963A80, CN963B80, CN963E75, CN983E80, CN964, CN965, CN980, CN981, manufactured by Toagosei Co., Ltd. Aronix M-1100, Aronix M-1200, Aronix M-1600, Kayarad UX-2201, Kayarad UX-2301, Kayarad UX-3204, Kayarad UX-3301, Kayarad UX-4101, Kayarad UX- 101, and the like.

Specific examples of the polyether oligomer include PO84F and LR-8894 manufactured by BASF.
Specific examples of the epoxy-based oligomer include, for example, Actilane 300, Actilane 310, Actilane 320, Actilane 320 DA25, Actilane 340, Actilane 330 made by AKCROS, EBECRYL600R EBEC NL , CN115, CN151 and the like.
Specific examples of the polyester-based oligomer include, for example, EBECRYL770, EBECRYL811, EBECRYL1830, manufactured by Daicel Ornex Co., Ltd., Aronix M-6100, Aronix M-6200, Aronix M-7100, manufactured by Toagosei Co., Ltd. A set 700, a beam set 710, a beam set 720, a beam set 730, a beam set 750, and the like can be given.
Specific examples of the acrylic oligomer include EBECRYL767 and EBECRYL1200 manufactured by Daicel Ornex.
These can be used in combination of several types. These also preferably have a hydroxyl group or a carboxyl group, which is a hydrophilic functional group, from the viewpoint of not affecting development.
Content of the photopolymerizable compound (C) used for the photosensitive electrically conductive paste of this invention is 1-100 weight part when the total weight part of organic binder (A) + (B) is 100. Is preferable, and more preferably 2 to 80 parts by weight. Content of photopolymerizable compound (C) is 1
When the amount is less than parts by weight, the curing reaction by light may be insufficient. On the other hand, when the amount exceeds 100 parts, the uneven spots on the surface and bottom of the cured coating become large, resulting in a non-uniform film. May be formed.

  Examples of the photopolymerization initiator (D) used in the photosensitive conductive paste of the present invention include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzophenone, 4,4-bis (dimethylamine) benzophenone, 4,4 -Bis (diethylamine) benzophenone, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 1,1-dichloroacetophenone, anthraquinone, 2-methylanthraquinone, 2-t-butylanthraquinone, 1- Chloroanthraquinone, thiosantone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, acetophenone dimethyl ketal, benzyl dimethyl Luketal, dibenzyl ketone, 4-benzoyl-4-methyldiphenyl ketone, anthrone, benzanthrone, 4-azidobenzalacetophenone, 2,6-bis (p-azidobenzylidene) cyclohexane, bis (2,4,6- Trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2- (o-ethoxycarbonyl) Examples thereof include oxime, 2-methyl- [4- (methylthio) phenyl] -2-morpholino 1-propane, naphthalenesulfonyl chloride, 4,4-azobisisobutyronitrile diphenyl disulfide, and the like. Examples of commercially available products include Oxe-01, Oxe-02 Irgacure 184, Irgacure 819, Irgacure 907, Irgacure 369, Irgacure 379EG, and Lucilin TPO manufactured by BASF.

More preferably, the photopolymerization initiator (D) includes oxime ester compounds such as Oxe-01 and Oxe-02, and aminoalkylphenone compounds such as Irgacure 907, Irgacure 369, and 379EG. Since the aminoalkylphenone compound and the oxime ester compound are very sensitive, the content of the photopolymerization initiator (D) can be reduced. As a result, it is preferable because the conductivity and wet heat reliability of the conductive coating film can be improved.
These known photopolymerization initiators can be used alone or in combination of two or more. By using a combination of two or more photopolymerization initiators, the sensitivity can be adjusted while considering solubility in a solvent.
The blending amount of such a photopolymerization initiator (D) is preferably 0.005 to 30 parts by weight when the total part by weight of (A) + (B) + (C) is 100, More preferably, it is 0.01-10 weight part. If the amount is less than 0.005 parts by weight, curing does not proceed to the deep part of the coating film, and poor adhesion may cause pattern adhesion failure, pattern peeling during development, and edge shape sharpness loss. When the amount is more than 30 parts by weight, the initiator remains, and the coating film may be tacky or the coating film reliability may be impaired.

The conductive paste of the present invention contains an organic solvent (E). As an organic solvent (E), it is preferable that a boiling point is 100 degreeC or more and less than 300 degreeC, More preferably, a boiling point is 130 degreeC or more and less than 280 degreeC.
Examples of the organic solvent (E) include Daicel's ethyl diglycol acetate (ECA), butyl glycol acetate (BCA), butyl diglycol acetate (BDGAC), and Exxon Chemical's Solvesso 100, 150, 200. Other examples include methyl isobutyl ketone, cyclohexanone, toluene, isophorone, γ-butyrolactone, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, benzyl alcohol, texanol, propylene glycol monomethyl ether acetate, and terpionol. These organic solvents can be used alone or in admixture of two or more.
Among these, a solvent having a boiling point of 130 ° C. or higher is preferred from the viewpoint of a conductive thin film production process using a photosensitive conductive paste. If the boiling point of the organic solvent (E) is too low, the solvent volatilizes during continuous printing by screen printing during the paste manufacturing process or use of the paste, and there is a concern that the component ratio of the conductive paste is likely to change. On the other hand, if the boiling point of the solvent is too high, the solvent may remain inside the coated film after drying, and part of the coated film may be transferred to the photomask when contacting the photomask in the exposure process. Therefore, the boiling point is preferably 280 ° C. or lower.
Against this background, a solvent having a boiling point of 110 ° C. or higher and a solvent having a boiling point lower than 280 ° C. may be used in combination. In the present invention, from the viewpoint of good screen printability (solvent volatility during continuous printing) and dryness, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, texanol, benzyl alcohol At least one solvent selected from the group consisting of ECA, BCA and BDGAC is preferred.
The content of the organic solvent (E) used in the photosensitive conductive paste of the present invention is 5 parts by weight or more when the weight part of (A) + (B) + (C) + (D) is 100 40 parts by weight or less, preferably 10 parts by weight or more and 35 parts by weight or less. When the content of the organic solvent (E) is less than 5 parts by weight, the viscosity of the conductive paste increases during continuous screen printing, and the printed shape may be blurred.
On the other hand, when the amount exceeds 40 parts by weight, the paste viscosity becomes low, and the printed shape may be smeared and unstable. Furthermore, the solvent may remain in the dried coating film, and may be set off when contacting with the photomask. In addition, the resulting coating film may be thin and electrical characteristics may be deteriorated.

In the electroconductive paste of this invention, you may mix | blend block isocyanate as a hardening | curing agent which can react with the photosensitive organic binder (A). The photosensitive organic binder (A) contained in the conductive paste of the present invention has a structure in which an alicyclic epoxy (meth) acrylate is added to a part of the carboxyl group of the (meth) acrylic copolymer. And a reactive hydroxyl group generated by the addition reaction. For this reason, storage stability improves by using the blocked isocyanate as a hardening | curing agent, and it is preferable. Moreover, it becomes possible to control a crosslinking density by using suitably the photopolymerizable compound (C) containing the hydroxyl group used as a reaction point.
By blending the blocked isocyanate, the heat resistance and wet heat reliability of the coating film can be expected to be improved by crosslinking with heat during drying of the coating film.

  The amount of the blocked isocyanate compound is preferably 0.05 to 15 parts by weight when the total part by weight of (A) + (B) + (C) + (D) is 100, More preferably, it is 10 parts by weight. If it is 0.05 parts by weight or less, the effect cannot be obtained, and if it exceeds 15 parts by weight, it remains in the coating film, and there is a concern of affecting the conductivity and coating film reliability. May occur. Furthermore, there is a concern that the blocking agent will scatter in the air and adversely affect the worker or the environment.

Examples of the isocyanate compound that constitutes the blocked isocyanate that can react with the photosensitive organic binder (A) and the photopolymerizable compound (C) of the present invention include aromatic or aliphatic diisocyanates, trivalent or higher polyisocyanates, and the like. Yes, either a low molecular compound or a high molecular compound may be used. For example, aliphatic diisocyanates such as hexamethylene diisocyanate and tetramethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, and isophorone diisocyanate. Alicyclic diisocyanates, or trimers of these isocyanate compounds, and excess amounts of these isocyanate compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine Low molecular active hydrogen compounds such as Polyester polyols, polyether polyols, terminal isocyanate group-containing compounds obtained by reacting a polymeric active hydrogen compound such as polyamides and the like.
The isocyanate group blocking agent includes, for example, an active methylene blocking agent such as ethyl acetoacetate, a phenol blocking agent such as phenol, cresol and xylenol, a pyrazole blocking agent such as dimethylpyrazole, Alcohol-based blocking agents such as methanol, ethanol, diethyl malonate, methyl lactate and ethyl lactate, oxime-based blocking agents such as methyl ethyl ketone oxime, diacetyl monooxime and cyclohexane oxime, mercaptan systems such as butyl mercaptan, t-butyl mercaptan and thiophenol Block agents, imide block agents such as succinimide, amine block agents such as aniline and butylamine, imidazole blocks such as imidazole and 2-ethylimidazole And imine-based blocking agents such as methyleneimine and propyleneimine. Among these blocking agents, dimethyl dimethyl is used from the viewpoint of compatibility between low-temperature curability and storage stability, flex resistance of the cured coating film, and hardness. Pyrazole and diethyl malonate are preferred.
The block isocyanate can be used even if it is commercially available, for example, Coronate 2509, 2512, Coronate 2513, Coronate 2520, manufactured by Nippon Polyurethane Industry Co., Ltd., MF-K60B, SBN-70D, TPA-B80E manufactured by Asahi Kasei Chemicals. , 17B-60PX, E402-B80T, SBN-70D, SBB-70P, Sumitomo Bayer Urethane Co., Ltd. Sumijour BL-3175, BL-4165, BL-1100, BL-1265, Death Module TPLS-2957, TPLS-2062 , TPLS-2078, TPLS-2117, Desmotherm 2170, Desmotherm 2265, Mitsui Takeda Chemical B-830, B-815, B-846, B-870, B-874, B-882, Baxenden BI798 , BI7951, BI7982, BI7960, BI7990, BI7991, BI7992, DP9C / 437 (Bakusenden Co., Ltd., trade name), manufactured by Showa Denko KK of Karenz MOI-BM, be mentioned Karenz MOI-BP or the like.
Among these, it is particularly preferable to use a blocked isocyanate blocked with a pyrazole derivative or diethyl malonate, and BI7982 and BI7960 are preferable. These blocked isocyanates may be used alone or in combination of two or more.

Examples of curing agents other than isocyanate compounds include known compounds such as amino resins such as methylated melamine, butylated melamine, benzoguanamine, and urea resin, acid anhydrides, imidazoles, epoxy resins, and phenol resins. These curing agents can be used in combination with a known catalyst or accelerator selected according to the type.
As a compounding quantity of a hardening | curing agent, it mix | blends to such an extent that the effect of this invention is not impaired, Although it does not restrict | limit in particular, 0.5-30 weight% with respect to a photosensitive organic binder (A). Is preferable, 1 to 20% by weight is more preferable, and 2 to 15% by weight is further preferable.

In the conductive paste of the present invention, the above-mentioned blocked isocyanate group deblocking catalyst and isocyanate group crosslinking reaction catalyst can be blended. For example, organic tin-based catalysts such as dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, triethylenediamine, triethylamine, N, N, N ′, N′-tetramethylpropylenediamine, N, N, N ′, N ′ -Tetrakis (2-hydroxypropyl) ethylenediamine, N-methylmorpholine, 1,2-dimethylimidazole, 1,5-diaza-bicyclo (4,3,0) nonene-5, 1,8-diaza-bicyclo (5, 4,0) -undecene-7 and other amine catalysts, amine salt catalysts such as borane salts, phenol salts, octylates and carbonates of these amine catalysts, magnesium naphthenate, lead naphthenate, potassium acetate, etc. Carboxylic acid metal salt catalysts, phosphorus catalysts such as triethylphosphine and tribenzylphosphine, sodium Alkoxide catalyst such as Umumetokishido, bismuth - Tris (2-ethyl hexane Nord), bismuth catalysts such as bismuth octylate.
Each of the blocked isocyanate group deblocking catalyst and the isocyanate group crosslinking reaction catalyst may be used alone or in combination of two or more.
The addition amount of the curing catalyst is preferably 0.01 to 40% by weight, more preferably 0.05 to 30% by weight, and still more preferably 0.1 to 20% by weight with respect to the blocked isocyanate.

  The photosensitive conductive paste of the present invention may contain an oxetane compound in addition to the above components. Examples of oxetane compounds include monofunctional oxetane compounds such as 3-ethyl-3-hydroxymethyloxetane manufactured by Ube Industries, Ltd., or Aron oxetane OXT-101, OXT-212, OXT-211, and OXT-213 manufactured by Toagosei Co., Ltd. be able to. Bifunctional oxetane compounds such as Aron Oxetane OXT-121 and OXT-221 can also be used as long as the conductive paste does not thicken with time. The amount of the oxetane compound is preferably 1 to 30 parts by weight when the total amount of the photosensitive organic binder (A) and the conductive powder (B) is 100 parts by weight.

The conductive paste of the present invention may contain a dispersant for the purpose of improving filler dispersibility and imparting dispersion stability.
Specific examples of the dispersant include Anti-Terra-U, Anti-Terra-203 / 204 Disperbyk-101, 107, 110, 111, 130, 161, 162, 163, 164, 165, 166, and 170 manufactured by Big Chemie Japan. 2020, 2155, BYK-P104, P105P104S, 240S, 2150, 2025, Fuka 44, 46, 47, 48, 49, 54, 63, 6 manufactured by Efka CHEMICALS
4, 65, 66, 71, 701, 764, 766, Fluorene TG-710, Kuroei SH-290, SP-1000, Polyflow No. 50E, No. 300, Disparon KS-860, 873SN, 874, # 2150, and # 7004 manufactured by Enomoto Kasei. The dispersant is preferably contained in the composition in an amount of 0.01 to 10% by weight.

In addition, as a specific example of the surface conditioning agent, it is preferable to add a surface conditioning agent to the conductive paste of the present invention in order to improve the wetting and spreading property to the substrate after coating the substrate. -350, 352, 354, 355, 358N, 361N, 381N, 381, 392, 380, 380N. BYK-300, 302, 306, 307, 310, 315, 320, 322, 323, 325, 330, 331, 333, 337, 340, 344, 370, 375, 377, 355, 356, 357, 390, UV3500, UV3510, UV3570, LF1980 manufactured by Enomoto Kasei Co., Ltd., Polyflow No. 90 manufactured by Kyoeisha Chemical Co., Ltd., and Tegorad-2100, 2200, 2250, 2500, 2700 manufactured by Tegochemy.
Among the above, as the surface conditioner used in the present invention, an acrylic surface conditioner is preferably used. The surface conditioner is preferably contained in the composition in an amount of 0.001 to 5% by weight. If the amount is less than 0.001% by weight, there is no effect. If the amount is more than 5% by weight, tackiness may be exhibited after drying, or the reliability of the coating film may be lowered. These surface conditioners may be used alone or in combination of two or more as required.

  The photosensitive conductive paste of the present invention may contain a polymerization inhibitor. The polymerization inhibitor is added to improve thermal stability during paste storage, and can suppress line weight by suppressing sensitivity during photocuring. Specific examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, N-nitrosodiphenylamine, phenothiazine, naphthoquinone, nitrosophenylhydroxylamine aluminum, pt-butylcatechol, N-phenylnaphthylamine, 2,6-di- Examples include t-butyl-p-methylphenol, chloranil, pyrogallol, p-methoxyphenol. The addition amount of the polymerization inhibitor is preferably 0.01 to 1% by weight in the total weight in the photosensitive conductive paste. If it is less than 0.01% by weight, there is no effect of addition, and if it exceeds 1% by weight, tackiness may occur on the surface, or curing may be insufficient due to a decrease in sensitivity, which is not preferable.

A sensitizer may be added to the photosensitive conductive paste of the present invention. Sensitivity can be improved by adding a sensitizer. Specific examples of the sensitizer include 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis (4-diethylaminobenzal) cyclopentanone, 2,6-bis (4-dimethylaminobenzal) cyclohexanone, 2,6-bis (4-dimethylaminobenzal) -4-methylcyclohexanone, Michler's ketone, 4,4'-bis (diethylamino) -benzophenone, 4,4'-bis (dimethylamino) chalcone, 4,4'- Bis (diethylamino) chalcone, p-dimethylaminocinnamylidene indanone, p-dimethylaminobenzylidene indanone, 2- (p-dimethylaminophenylvinylene) -isonaphthothiazole, 1,3-bis (4-dimethylaminoben) Colander) acetone, 1,3-carbonyl-bis (4-diethyla) Nobenzal) acetone, 3,3′-carbonyl-bis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N-phenylethanolamine, N-tolyldiethanolamine, N-phenylethanolamine, dimethylaminobenzoic acid Examples thereof include isoamyl, isoamyl diethylaminobenzoate, 3-phenyl-5-benzoylthiotetrazole, and 1-phenyl-5-ethoxycarbonylthiotetrazole. In the present invention, one or more of these can be used. Some sensitizers can also be used as photopolymerization initiators. It is preferable that it is 0.05-30 weight% normally with respect to the photosensitive organic binder (A), More preferably, it is 0.1-20 weight%. If the amount is less than 0.05% by weight, the effect of improving the sensitivity is small. If the amount exceeds 30% by weight, the surface may have tackiness or excessive light absorption may reduce the light sensitivity.

  In addition to the photopolymerization initiator, the photosensitive conductive paste of the present invention can be used in combination with a thermal polymerization catalyst. This thermosetting catalyst can react not only the thermosetting component but also an uncured photopolymerizable monomer by aging at a high temperature. Examples of such a thermosetting catalyst include 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2′-azobisisobutyronitrile, and 2,2′-azobis-2-methyl. Butyronitrile, 2,2'-azobis-2,4-divaleronitrile, 1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis- 4-cyanovaleric acid, 2-methyl-2,2′-azobispropanenitrile, 2,4-dimethyl-2,2,2 ′, 2′-azobispentanenitrile, 2,2,2 ′, 2 '-Azobis (2-methylbutanamide oxime) dihydrochloride, peroxides such as benzoyl peroxide, and the like.

  The photosensitive conductive paste of the present invention may contain an antioxidant in order to prevent oxidation of the photosensitive organic binder (A). 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylene-bis (4-methyl-6-t -Butylphenol), 2,2′-methylene-bis (4-ethyl-6-tert-butylphenol), 4,4′-bis (3-methyl-6-tert-butylphenol), 1,1,3-tris ( 2-methyl-4-hydroxy-6-tert-butylphenyl) butane, bis [3,3-bis- (4-hydroxy-3-tert-butylphenyl) butyric acid] glycol ester, dilaurylthiodipropionate And triphenyl phosphite. When adding antioxidant, it is preferable that the addition amount is 0.01 to 1 weight% with respect to the photosensitive organic binder (A).

The photosensitive electrically conductive paste of this invention can add the compound which has a functional group which can react with isocyanate.
By adding a compound having a functional group capable of reacting with isocyanate, it is possible to increase the number of cross-linking points in the reaction with the blocked isocyanate contained in the present invention, and to adjust the distance between the cross-linking points. The cured coating film properties can be adjusted.
The functional group capable of reacting with isocyanate is preferably a hydroxyl group or an amino group, and may have either one or both. Specific examples of the compound include dimethylolbutanoic acid and dimethylolpropionic acid, 1,2-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2,2- Dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2- Dimethyl-3-hydroxypropyl-2 ′, 2′-dimethyl-3-hydroxypropanoate, 2-normalbutyl-2-ethyl-1,3-propanediol, 3-ethyl-1,5-pentanediol, 3- Propyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol 2 in 1 molecule such as 3-phenyl-1,5-pentanediol, 2,5-dimethyl-3-sodium sulfo-2,5-hexanediol, dimer diol (PRIPOL-2033 (manufactured by Unikema International)), etc. One or more hydroxyl groups and amino groups in one molecule such as a compound having one hydroxyl group, polymethyl alcohol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, polyglycerin, monoethanolamine, diethanolamine, triethanolamine Fats such as amino alcohol, ethylenediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, etc. Group diamine and metaxylenediamine, 4,4 ' Examples thereof include compounds having two amino groups in one molecule, such as aromatic diamines such as -diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether. The above-mentioned compound having a functional group capable of reacting with two or more isocyanates per molecule having a number average molecular weight of less than 1,000 may be used alone or in combination with a plurality of compounds without any problem.
Among these, 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid containing a carboxylic acid for imparting alkali solubility are preferred.

The photosensitive conductive paste of the present invention may have conductive titanium oxide which is a nonmetal. By adding conductive titanium oxide, the mechanical strength of the coating film can be improved while maintaining conductivity, and the contact resistance value is improved in the anchor effect between the conductive thin film and the substrate. can do. Examples of conductive titanium oxide include ET-300W, ET-500W-ET-600W, SN-100P, FT-1000, FT-2000, FT-3000, FT-4000, and FS-10P manufactured by Ishihara Sangyo Co., Ltd. Used.
The addition amount of the conductive titanium oxide is preferably 0.1 to 5 parts by weight or 0.3 to 2 parts by weight when the total paste part by weight is 100. When the amount is less than 0.1 parts by weight, the effect of increasing the conductivity and the effect of increasing the mechanical strength are small. On the other hand, when the value is more than 5 parts by weight, the conductivity of the conductive thin film and the adhesion to the base material are decreased, and light is scattered during photocuring, and the curability may be significantly decreased. is there.

  The photosensitive conductive paste of the present invention may contain nonmetals such as carbon-based fillers such as carbon black and graphite powder. By adding carbon black and graphite powder, conductivity and printability can be improved. Among these, carbon black is particularly preferable, and the amount of carbon black added is preferably 0.1 to 5 parts by weight or 0.3 to 2 parts by weight when the total weight part of the paste is 100. When the amount is less than 0.1 part by weight, the effect of increasing the conductivity is small. On the other hand, when the value is more than 5 parts by weight, the conductivity of the conductive thin film and the adhesion to the substrate are lowered, and the carbon black absorbs light during photocuring, so that the curability is significantly lowered. There is a case.

In the conductive paste of the present invention, an anti-settling agent can be added. Anti-settling agents include fatty acid amide wax, polyethylene oxide, amine salt of polymer polyester, linear polyaminoamide and salt of polymer acid polyester, amide solution of polycarboxylic acid, alkyl sulfonate, alkyl allyl sulfonate, Known and commonly used filler anti-settling agents such as colloidal ester, aluminum stearate, zinc stearate, white carbon, lecithin and ethyl oleate can also be used. Examples of those commercially available include Disparon # 6900-20X, Disparon. # 4200-10, 4200-20, Disparon KS-873N, Disparon # 1850 (manufactured by Enomoto Kasei Co., Ltd.), BYK-405 (Bic Chemie Japan, Inc.) can be used. In addition, organic bentonite mainly composed of montmorillonite can also be used. Examples of commercially available ones include Bengel, Bengel FW, Esven, Esben 74, Organite, Organite T (above, Toyoshun Yoko Co., Ltd.) ), Orben, 250M, Benton 34, Benton 38 (above, manufactured by Wilber Ellis), Laponite, Laponite RD, Laponite RDS (above, Nihon Silica Kogyo Co., Ltd.), A-S-AT-20S, A -S-AT-350F, A-S-AD-10A, A-S-AD-160 (above, manufactured by Ito Oil Co., Ltd.) and the like can be mentioned, and these can be used alone or in combination of two or more. . The organic bentonite may be dispersed in an organic solvent.
These filler antisettling agents can be used alone or in combination of two or more.
The amount of the anti-settling agent used depends on the amount of silver powder and solvent used, and is not limited to a specific ratio, but generally 0.5 parts per 100 parts by weight of the organic photosensitive binder (A). -20 parts by weight is suitable, preferably 1-10 parts by weight. If the amount of anti-settling agent used is too small, the uniform dispersibility of the binder and filler and the storage stability of the composition may be reduced. If the amount of the anti-settling agent used is too large, it may be adversely affected on the substrate adhesion and conductivity, which is not preferable.

  In the conductive paste of the present invention, a resin having no photopolymerizability can be blended for the purpose of improving adhesion and developing property. For example, urethane resin other than cellulose resin, polyester resin, polyurethane resin, epoxy resin, phenol resin, acrylic resin, styrene-acrylic resin, styrene-butadiene copolymer, polystyrene, polyamide resin, polycarbonate resin, vinyl chloride-vinyl acetate Polymerized resin, ethylene-vinyl acetate copolymer resin, and the like can be used, and there is no restriction on the combined use.

  In addition to the above components, the conductive paste of the present invention contains light such as benzotriazole-based UV absorbers, triazine-based UV absorbers, oxalic anilide-based UV absorbers, hindered amine light stabilizers, and the like. Stabilizers, phenolic antioxidants, phosphite antioxidants, thioether antioxidants, antioxidants such as phosphites, organic resin fine particles, fatty acid amide waxes, polyamide waxes, polyethylene waxes, oxidation Viscosity modifiers such as polyethylene wax, silica, organic bentonite, urea compound viscosity modifiers, surface modifiers such as vinyl compound surface modifiers, defoamers such as silicone defoamers, vinyl compound defoamers , Acidic phosphate-based curing catalysts and sulfonic acid-based curing catalysts, acetylacetone, benzotria Metal chelating agents such Lumpur acids, more can be used carbodiimide, epoxy and the like, alone or in combination as the resin decomposition inhibitor.

  Furthermore, an inorganic substance can be added to the conductive paste of the present invention. Examples of inorganic substances include silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, diamond carbon lactam, and other carbides; boron nitride , Various nitrides such as titanium nitride and zirconium nitride, various borides such as zirconium boride; various oxides such as titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide and aluminum oxide; calcium titanate , Various titanate compounds such as magnesium titanate and strontium titanate; sulfides such as molybdenum disulfide; various fluorides such as magnesium fluoride and carbon fluoride; aluminum stearate, calcium stearate, zinc stearate, Various metal soaps such as magnesium stearate and the like; may be used talc, bentonite, talc, calcium carbonate, bentonite, kaolin, glass fiber, mica or the like. By adding these inorganic substances, it may be possible to improve printability, heat resistance, and mechanical strength.

  The conductive paste of the present invention preferably has an F value of 55 to 95%, more preferably 75 to 90%. The F value is a numerical value indicating the filler part by weight with respect to 100 parts by weight of the total solid content contained in the paste, and is represented by F value = (filler part by weight / solid part by weight) × 100. The filler parts by weight here are parts by weight of the conductive powder, and the solid parts by weight are parts by weight of components other than the solvent. The conductive powder, photosensitive organic binder, photopolymerizable compound, and photopolymerization start. Contains all additives, organic solvents and other blocked isocyanates and additives. When the F value is less than 55%, good conductivity cannot be obtained, and when it exceeds 95%, the adhesion and / or hardness tends to decrease. Furthermore, a decrease in developability is inevitable. Here, the conductive powder refers to both the conductive powder (B) and the conductive powder made of a nonmetal.

The scratch by the grind gauge measurement of the photosensitive conductive paste of the present invention is preferably 10 μm or less, and more preferably 5 μm or less. Particularly preferably, it is 3 μm or less. When the thickness is 10 μm or less, the smoothness of the coating film becomes good, and the fine line property by development becomes good. On the other hand, when the scratch mark by the grind gauge is larger than 10 μm, the smoothness of the coating film is deteriorated, and as a result, the fine line property by development is remarkably deteriorated.
Grind gauge measurement is a scratch formed when the paste is scraped horizontally from a depth of 25 μm to 0 μm on a grooved plate having a depth of 25 μm at one end and a depth of 0 μm at the other end. It means the length of.
Examples of the method for controlling the scratch by the grind gauge measurement within the above range include a method of filtering the photosensitive conductive paste with a predetermined filter described later.

Although the manufacturing method of the photosensitive electrically conductive paste of this invention is not specifically limited, For example, it can manufacture by the following processes. First, the photosensitive organic binder (A) is dissolved in the organic solvent (E). Next, conductive powder (B), photopolymerizable compound (C), photopolymerization initiator (D), and other additives such as blocked isocyanate and anti-settling agent are added to this solution, and double planetary, dissolver, planet Preliminary dispersion is carried out with an agitator of the type. Subsequently, this is disperse | distributed with a 3 roll mill, and an electroconductive paste is obtained. The conductive paste obtained by such a process is further filtered as described later.
Further, in a conductive paste with a low solvent content as in the present invention, a dispersion process using a three-roll mill is particularly effective in terms of production efficiency, but other dispersers such as a bead mill, a kneader, an extruder, etc. There is no problem even if it is distributed using.

Hereinafter, the filtration process of the photosensitive conductive paste in the present invention will be described.
As a filter for filtering the photosensitive silver paste, a filter having an opening of 30 μm or less is used. When a filter having a mesh opening of more than 30 μm is used, undispersed conductive powder, coarse particles, foreign matter, etc. cannot be removed, and protrusions are formed on the paste coating film surface, resulting in a decrease in smoothness. As a result, developability deteriorates, fine pattern properties cannot be obtained, and short circuit failure occurs.
On the other hand, the opening is preferably 3 μm or more, and if it is finer than this, depending on the particle diameter of the silver powder, the filtration rate is remarkably lowered, and finally the filtration filter is clogged. As a result, the number of filtration filter replacements increases, and the production efficiency decreases significantly.

  The material of the filter for filtering the photosensitive silver paste is not particularly limited, such as stainless steel, nickel, polyester, nylon, PTFE (polytetrafluoroethylene), polypropylene and other metals, but stainless steel is preferable from the viewpoint of durability. Moreover, there is no restriction | limiting in order to raise the filtration precision by carrying out the flat process, the Teflon (trademark) process, etc. on the filter surface made from these.

The method of filtering the photosensitive silver paste is not particularly limited, but the method of scraping the paste with its own weight while stirring and rotating a stirring blade made of plastic (for example, polyoxymethylene) with excellent wear resistance is apparatus-like. In addition, the manufacturing efficiency is good.
The number of rotations of stirring is not limited as long as paste filtration does not impair manufacturing efficiency.
As these filters, PF160A and PF320A manufactured by Protech Co., Ltd. are preferable. In addition, there is no restriction on improving the filtration efficiency by pressurizing or depressurizing as an option of the apparatus.
In addition, heat generation may occur during filtration, but if the temperature of the photosensitive conductive paste increases, the stability of the particles decreases, causing problems such as re-aggregation, and some materials undergo a curing reaction. This may cause foreign matter. For this reason, in order to prevent an increase in the temperature of the photosensitive conductive paste during filtration, it is preferable to equip the filtration device with a cooling device.

  When pressurizing with the aim of improving the filtration efficiency of the photosensitive silver paste, the pressure above atmospheric pressure may be set as appropriate according to the viscosity of the paste, the filtration efficiency, etc., and is not particularly limited. In view of work safety, productivity, etc., the range is preferably 0.1 to 0.4 MPa, more preferably 0.2 to 0.4 MPa, and 0.25 to 0. A range of 35 MPa is particularly preferable.

  Judgment as to whether foreign matter and aggregates have been removed by the above filtration can also be judged by the number of foreign matters remaining on the filter without passing through the filter, but it is possible to measure the grind gauge of the paste after filtration. The effect can also be confirmed by measuring the surface roughness (Ra) of the conductive thin film formed through a predetermined process.

It is preferable that the surface smoothness (Ra) of a coating film produced through a predetermined procedure using the photosensitive conductive paste of the present invention is 0.40 μm or less.
By using the photosensitive silver paste actually filtered with the filter of 30 μm or less, coarse particles and foreign matters are cut, and the arithmetic average roughness Ra value can be reduced to 0.40 μm or less.
Further, by setting the Ra value to 0.40 μm or less, the regular orientation of the conductive material is increased, so that the resistance value of the conductive circuit can be stabilized and the surface smoothness is good during the exposure process. By reducing the scattering of UV light on the coating surface, it is possible to obtain a highly linear conductive circuit during subsequent development. If Ra exceeds 0.40 μm, coating smoothness is poor and UV exposure In this case, the fine line property after development deteriorates due to scattering of UV light. On the other hand, the lower limit is not particularly set, but if the coating film smoothness is good, the conductive filler is difficult to appear on the surface and the conductivity is lowered. Therefore, the lower limit is preferably 0.05 μm or more.
Here, the arithmetic average roughness Ra value is defined in JIS B 0601-1994.

The procedure for forming a conductive thin film or fine wire using the photosensitive conductive paste of the present invention includes the following steps (1) to (4).
(1) The process of apply | coating the photosensitive electrically conductive paste on a base material, and drying at the temperature of 110 degrees C or less,
(2) Next, a step of exposing a part of the applied photosensitive conductive paste,
(3) Next, the step of developing the unexposed portion (4) The step of drying the unexposed exposed portion at a temperature of 140 ° C. or lower (1) For the conductive paste of the present invention, the screen printing method, spin coating, A coating film is formed by applying or printing on a substrate using a bar coater, a blade coater, a dip method or the like.
The coating method may be any of the above-described coating methods, but it is preferably performed by a screen printing method from the viewpoint of productivity and quality stability. Although it does not specifically limit as a base material, For example, base materials, such as a polycarbonate, an acryl, a polyimide, polyester, are mentioned. Moreover, a conductive laminated body can be obtained by providing a transparent conductive layer between the said base material and a conductive film, and laminating | stacking a conductive thin film on a transparent conductive layer. The material of the transparent conductive layer is not particularly limited. For example, a conductive thin film of ITO film mainly composed of indium tin oxide can be applied. Further, the transparent conductive layer is not limited to the one formed on the entire surface of the base material, but a layer obtained by removing a part of the transparent conductive layer by etching can also be used. In addition, a substrate such as a glass substrate, a glass epoxy substrate, a glass polyimide substrate, a ceramic substrate, a polyimide substrate, a bismaleimide triazine) plate, a phenol substrate, or paper phenol can be used.
Next, the pattern formed on the substrate as described above is dried, for example, at about 60 to 110 ° C. for about 3 to 30 minutes using, for example, a hot air circulation drying furnace or a far infrared drying furnace, and the organic solvent inside the coating film is evaporated. It is necessary to let This is because it is necessary to reduce the tackiness because it is necessary to bring the coating film formed in the next exposure step into contact with the negative mask.
In addition, there is no problem even if the photosensitive electrically conductive paste of this embodiment is used as a dry film formed into a film in advance.
The film thickness of the pattern obtained by drying is preferably 3 μm or more, more preferably 4 m or more, from the viewpoint of good developability and the conductivity of an electric circuit. On the other hand, from the viewpoint of developability, the thickness is preferably 12 μm or less, and more preferably 10 μm or less, from the viewpoint that if the thickness is large, the developer does not sufficiently penetrate into the coating film and a large amount of residue remains.

In step (2), the coating film prepared in (1) is subjected to pattern exposure through a photomask and developed. As an exposure method, for example, contact exposure or non-contact exposure using a photomask (negative type or positive type) having a predetermined exposure pattern is generally used, but directly using a laser beam or the like without using a photomask. A drawing method may be used. As the exposure light source, a halogen lamp, a high-pressure mercury lamp, a laser beam, a multi-lamp, a metal halide lamp, a black lamp, an electrodeless lamp, or the like is used. The exposure amount is preferably about 50~1000mJ / cm ^2, line thickening and, from the viewpoint of ^{productivity, 100mJ / cm 2 ~600mJ / cm} 2 is more preferred.
In the step (3), as a developing method, a spray method, a dipping method or the like is used. As the developer, for example, when the photosensitive conductive paste contains a carboxyl group, a metal alkali aqueous solution such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, monoethanolamine, diethanolamine, triethanol, etc. An aqueous amine solution such as an amine is used. The developer concentration is preferably 0.01 to 10% by weight, and more preferably 0.1 to 5% by weight. If the concentration of the aqueous alkali solution is less than 0.01% by weight, the soluble part tends to be removed, and if it exceeds 10% by weight, the pattern part tends to be peeled off and the insoluble part tends to corrode. The development temperature during development is preferably 20 to 50 ° C. in terms of process control, provided that the carboxyl group is neutralized and the unexposed area is removed. These developer, developer concentration, The developing temperature is not limited. Further, after the development, it is preferable to perform washing with water and acid neutralization in order to remove unnecessary developer.
For the above development step, it is preferable to use a continuous tank type developing device provided with an alkali developer, water washing, an acid neutralization zone, and further a drying zone, since the production efficiency is improved.
As described above, the pattern coating film of the photosensitive conductive paste obtained by exposure and development is post-dried and post-cured to form an electrode pattern.
About a process (4), it is preferable to use a hot-air circulation type drying furnace, a far-infrared drying furnace, etc. similarly to a process (1). About drying and hardening temperature, an electrode pattern is formed by heat-processing a pattern coating film at the temperature of 100-180 degreeC, Preferably it is the temperature of 110-140 degreeC for about 10 to 60 minutes.
When final curing is performed at a temperature lower than 100 ° C., the curing reaction does not proceed, and further, the solvent may remain, so that desired conductivity may not be exhibited. On the other hand, when the final curing is performed at a temperature higher than 180 ° C., the base material may be deformed, and the adhesion may be lowered.

  A touch panel can be manufactured using the conductive laminate of the present invention. The touch panel may be a resistive film type or a capacitive type. Although it can be applied to any touch panel, since this paste is suitable for forming a thin line, it is preferably used for a capacitance method.

  Although it does not specifically limit as a manufacturing method of a touch panel, For example, on the base material which laminated | stacked transparent conductive layers, such as an ITO film | membrane, it applied and printed the conductive paste, and produced through exposure and development. The conductive circuit can be cured by heating to form a conductive laminate, and the obtained conductive laminate can be bonded to another conductive laminate.

  The conductive paste of the present invention is preferably used for electrode circuit wiring of touch panels, but besides that, it is used for electromagnetic shielding applications, electronic component circuit formation applications, conductive adhesives for terminals and lead wires, etc. Can also be used.

  The photosensitive conductive paste of the present invention can be used as a conventional screen printing paste as long as it can be finally cured by heat and light. Other printing methods such as gravure printing and letterpress printing can also be applied.

  The present invention will be described more specifically with reference to the following examples and comparative examples. In addition, this invention is not limited to the following embodiment. Further, unless otherwise specified, “parts” in the examples indicates “parts by weight”, and the solid content concentration indicates a nonvolatile content after the organic solvent is completely volatilized.

  The conductive paste in the present invention was evaluated by the following method.

1. Number average molecular weight

2. Acid value 0.2 g of sample resin was precisely weighed and dissolved in 20 ml of chloroform. Subsequently, it titrated with 0.01N potassium hydroxide (ethanol solution). A phenolphthalein solution was used as an indicator. The unit of the acid value was eq / ton, that is, the equivalent per 1 ton of the sample.

3. Grind gauge measurement The grind gauge value of the photosensitive conductive paste was measured using a grind gauge (manufactured by TAIYU). For the value, the position where the scratch was generated was read, the measurement was performed twice on the same sample, and the larger value was adopted.

4). Measurement of arithmetic average roughness (Ra) (preparation of arithmetic average roughness evaluation sample)
An ST400 stainless steel mesh (plate size: 320 mm, emulsion thickness: 10 μm, wire diameter: 23 μm) manufactured by Tokyo Process Service Co., Ltd. was used as a screen plate on a PET film (Lumirror S manufactured by Toray Industries, Inc.) that had been annealed to a thickness of 100 μm. A solid coating pattern for development evaluation of 120 mm was formed and dried at 90 ° C. for 10 minutes in a hot air circulation drying oven to form a silver pattern with good touch drying properties. The squeegee pressure was 0.4 MPa, the squeegee speed was 100 mm / sec, and the clearance was 1.5 mm.
After pattern formation, a silver pattern for Ra measurement was formed by drying at 90 ° C. for 10 minutes in a hot air dryer.
(Measurement of arithmetic average roughness (Ra))
The arithmetic surface roughness Ra value (μm) of the above pattern was measured using Tokyo Seimitsu Co., Ltd. (model name Handy Surf, E-35B manufacturer). The measurement conditions were a cut-off value of 0.8 mm and a measurement length of 10 mm.
5. Preparation of Conductive Laminate Test Piece for Measuring Physical Properties A 400-mesh polyester screen is applied to each of a PET film (Lumirror S manufactured by Toray Industries, Inc.) and an ITO film (KH300 manufactured by Oike Kogyo Co., Ltd.) having a thickness of 100 μm. A conductive paste was printed by a screen printing method using, and dried at 90 ° C. for 10 minutes in a hot air circulation type drying furnace to form a pattern having a width of 80 mm and a length of 120 mm. In addition, the coating thickness at the time of printing was adjusted so that a dry film thickness might be set to 4-6 micrometers.
Thereafter, the pattern was exposed to an integrated light amount of 150 mJ / cm ² , developed using a 0.2 wt% Na ₂ CO ₃ aqueous solution having a liquid temperature of 25 ° C., and then washed with water. Then, thermosetting was performed at 140 ° C. for 30 minutes in a hot-air circulation type drying furnace, and a conductive laminate test piece having a specific resistance, adhesion, width 25 mm, and length 100 mm for measuring pencil hardness as shown below was produced.

6). The specific resistance was measured by measuring the sheet resistance and film thickness of a conductive laminate test piece produced on a PET film with a specific resistance of 3. For the film thickness, a gauge stand ST-022 (manufactured by Ono Sokki Co., Ltd.) was used, and the thickness of the cured coating film was measured at five points with the thickness of the PET film as the zero point, and the average value was used. The sheet resistance was measured for four test pieces using MILLIOHMMETER 4338B (manufactured by HEWLETT PACKARD), and the average value was used.

7). Evaluation by peel test using cello tape (registered trademark) (manufactured by Nichiban Co., Ltd.) in accordance with JIS K-5400-5-8: 1990 using the conductive laminate test piece produced on the ITO film with adhesion 3 did. However, the number of cuts in each direction of the lattice pattern was 11, and the cut interval was 1 mm. 100/100 indicates that there is no peeling and good adhesion, and 0/100 indicates that all are peeled off.

9. The conductive laminate test piece produced on the ITO film with a pencil hardness of 3 was placed on a 2 mm thick SUS304 plate, and the pencil hardness was measured according to JIS K 5600-5-4: 1999.

10. Moisture and heat resistance test:
The conductive laminate test piece prepared on the ITO film in step 3 was left at 85 ° C. and 85% RH (relative humidity) for 120 hours, and then taken out. Then, after leaving at room temperature for 24 hours, various evaluations were performed.

11. Paste viscosity Viscosity was measured at 20 rpm using a BH viscometer (manufactured by Toki Sangyo Co., Ltd.) at a sample temperature of 25 ° C.

12 Storage stability of conductive paste The conductive paste was placed in a plastic container and sealed and stored at 25 ° C. for 1 month. 2. Viscosity measurement after storage and above 3. The test piece produced by the conductive laminate test piece was evaluated.
◯: There is no significant change in viscosity, and the initial specific resistance, pencil hardness and adhesion are maintained.
X: Either a significant increase in viscosity (more than twice the initial viscosity) or a significant decrease in viscosity (1/2 or less of the initial viscosity) and / or a decrease in specific resistance, pencil hardness and / or adhesion are observed. .

13. Developability test:
Evaluation items and measurement conditions for developability are as follows.
14 Production of Test Piece for Development A conductive paste was printed by screen printing on an annealed ITO film (KH300, manufactured by Oike Industry Co., Ltd.). ST400 stainless steel mesh (plate size 320 mm, emulsion thickness 10 μm, wire diameter 23 μm) manufactured by Tokyo Process Service Co., Ltd. was used as the screen plate, and a solid coating pattern for development evaluation with a width of 80 mm and a length of 120 mm was formed. The film was dried at 90 ° C. for 10 minutes in a drying furnace to form a silver pattern having good touch drying properties.
In addition, the coating thickness at the time of printing was adjusted so that a dry film thickness might be set to 4-6 micrometers.
Screen printing conditions were a squeegee pressure of 0.4 MPa, a squeegee speed of 100 mm / sec, and a clearance of 1.5 mm.
In addition, the coating thickness at the time of printing was adjusted so that a dry film thickness might be set to 4-6 micrometers.

15. Preparation of developability evaluation sample Then, a high pressure mercury lamp was used as a light source, and pattern exposure was performed such that the integrated light amount on the composition was 150 mJ / cm ² through a negative mask. Next, development was performed using a 0.2 wt% Na ₂ CO ₃ aqueous solution having a liquid temperature of 25 ° C., and then washed with pure water at 25 ° C. The development time was 40 seconds and the washing time was 60 seconds. After that, it is cured in a hot-air circulating drying oven at 140 ° C for 30 minutes, and a pattern (design pattern) with a line / space (L / S) width of 30 / 30μm, length of 60m, and 7m as shown in the figure is measured. Two test pieces were formed.

16. About developability evaluation and conductive thin film characteristic evaluation after development (process width evaluation of conductive thin film after development) 5
In the development evaluation test piece, the line width of the conductive film at the remaining portion was measured. The measurement was performed using a laser microscope (Keyence VHX-1000), and the determination was made according to the following evaluation criteria.
○: The line width of the conductive thin film remaining after development is 28 to 32 μm.
Δ: The line width of the conductive thin film remaining after development is 24 to 27 μm or 33 to 36 μm.
X: The line width of the conductive thin film remaining after development is 23 μm or less, or 37 μm or more.

(Developability evaluation 1 Conductivity between both ends of fine wire)
The development evaluation test piece was evaluated based on whether or not conduction between both ends of the thin wire was ensured. Specifically, check the presence or absence of continuity by applying testers between terminals 1a and 1c, between terminals 2a and 2c, between terminals 3a and 3c, and between terminals A4a and 4c. Judged.
○: Conduction between both ends of the fine wire for all four fine wires. Δ: Conductivity between both ends of the thin wires for one of the four thin wires ×: Fine wires for all four thin wires No conduction between both ends (Developability evaluation 2 Insulation between adjacent fine wires)
The development evaluation test piece was evaluated based on whether insulation between adjacent thin wires was secured. Specifically, the presence / absence of conduction was confirmed by applying a tester between each of the terminals 1a and 2a, between the terminals 2a and 3a, and between the terminals 3a and 4a, and judged according to the following evaluation criteria.
○: All adjacent fine wires are insulated △: Some adjacent fine wires are insulated ×: All adjacent fine wires are not insulated

(Evaluation of unexposed residue after development)
After the exposure, in the evaluation test piece after development, an unexposed portion to be developed other than the conductive thin film formed by exposure was observed with a microscope, and the presence or absence of residue was determined according to the following evaluation criteria.
○: There is no residue in the unexposed area to be developed.
Δ: There are some residues at unexposed areas to be developed.
X: Many residues are seen in the unexposed areas to be developed.

(Evaluation of adhesion between conductive thin film and substrate after development)
The adhesion of the conductive thin film portion where the conductive thin film after development remained to the substrate was evaluated by a tape peeling test using cello tape (registered trademark) (manufactured by Nichiban Co., Ltd.). This evaluation was performed immediately after 24 hours (initial stage) after the test piece was prepared, and after that, after further standing in a moist heat environment of 85 ° C. and 85% RH (relative humidity) for 120 hours and then at room temperature for 24 hours (moisture heat resistance). After the test).
○: No peeling. Δ: Partially peeled off. X: All peel.

12 Moisture and heat resistance test (2)
The developed wiring prepared in 6 was heated at 85 ° C. and 85% RH (relative humidity) for 240 hours, and then allowed to stand at room temperature for 24 hours, and then the resistance value was measured. For the resistance value, the average value of the three patterns was adopted, and the judgment criteria were as follows.
○: The variation of the resistance value is less than 20% with respect to the initial resistance value.
(Triangle | delta): The fluctuation | variation of a resistance value is 20% or more with respect to an initial stage resistance value.
X: The variation of the resistance value is 30% or more with respect to the initial resistance value.

Example 1
As photosensitive organic binder (A), Daicel Ornex Co. (ACA) Z320 (solid content concentration 39 wt%) is 2564 parts (1000 parts as solid part (including 1564 parts dipropylene glycol monomethyl ether as solvent (E)) ), 8,940 parts of spherical silver powder (D50 = 1.5 μm) as the conductive powder (B), 480 parts of PETIA (pentaerythritol triacrylate) manufactured by Daicel Ornex as photopolymerizable compound (C), light 2.5 parts Oxe-01 manufactured by BASF as a polymerization initiator (D), 50 parts Polyflow No. 90 manufactured by Kyoeisha Chemical Co., Ltd. as a leveling agent, Disperbyk 2155 manufactured by BYK Japan Japan Co., Ltd. as a dispersant. And 60 parts of dipropylene glycol monomethyl ether as solvent (E). The mixture was passed through a three-roll kneader and dispersed three times.
Next, a 635 mesh (stainless mesh filter (filter having a diameter of 20 μm, opening of 20 μm) was attached to a paste filter (Protech PF320A), and the paste was filtered. The conductive paste was printed on a PET substrate and ITO film (KH300, manufactured by Oike Kogyo Co., Ltd.) in a predetermined pattern, and then dried with a hot air dryer at 90 ° C. for 10 minutes to obtain a conductive thin film. Thereafter, exposure, development, and final drying were performed using the conductive thin film, and basic properties such as specific resistance, adhesion, and pencil hardness were measured to evaluate developability. The evaluation results of the properties are shown in Table 1.

Examples 2-11
Examples 2 to 11 were carried out by changing the resin and formulation of the conductive paste, and paste filtration was performed in all. Table 1 shows the formulation and evaluation results of the conductive paste. In the examples, good coating film properties and fine line developability could be obtained. Also, the adhesion to the ITO film and the adhesion after the wet heat environment test were good.

In Table 1, the following were used as the photosensitive organic binder, conductive powder, photopolymerizable compound, photopolymerization initiator, organic solvent, and other compounds.

Photosensitive organic binder A (1): Acrylic copolymer having a carboxyl group (ACA) Z320 (weight average molecular weight: 23000, acid value 2300 eq / ton, solid content concentration 39.0 wt%, manufactured by Daicel Ornex Co., Ltd.
Photosensitive organic binder A (2): Acrylic copolymer having a carboxyl group, manufactured by Daicel Ornex (ACA) 30 (weight average molecular weight: 23600, acid value 2020 eq / ton, solid content concentration 46.8 wt%
Photosensitive organic binder A (3): Acrylic copolymer having a carboxyl group (ACA) Z251 (weight average molecular weight: 15000, acid value 1200 eq / ton, 45.5 wt%, manufactured by Daicel Ornex Co., Ltd.)
Photosensitive organic binder A (4): Acrylic copolymer having a carboxyl group ACA200M manufactured by Daicel Ornex (weight average molecular weight: 13200, acid value 2000 eq / ton, solid content concentration 48.6 wt%
Conductive powder B (1): Spherical silver powder (D50: 1.5 μm)
Conductive powder B (2): Aggregated silver powder (D50: 6.1 μm)
Conductive powder B (3): flaky silver powder (D50: 3.0 μm)
Conductive powder B (4): plate-like silver powder (D50: 0.4 μm)
Photopolymerizable compound C (1): PETIA (pentaerythritol triacrylate) manufactured by Daicel Ornex
Photopolymerizable compound C (2): Sartomer SR399E (dipentaerythritol hydroxypentaacrylate) manufactured by Nippon Kayaku Co., Ltd.
Photopolymerizable compound C (3): Kayrad NPGDA (Neopentyl glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd.
Photopolymerization compound C (4): EB770 (polyester acrylate) manufactured by Daicel Ornex
Photoinitiator D (1): BASF Irgacure Oxe-01
Photopolymerization initiator D (2): Irgacure 907 manufactured by BASF
Photopolymerization initiator D (3): BASF Irgacure 379EG
Organic solvent E (1): Dipropylene glycol monomethyl ether (Hisolv DPM) manufactured by Toho Chemical Co., Ltd.
Organic solvent E (2): Propylene glycol monomethyl ether (Hisolv PM) manufactured by Toho Chemical Co., Ltd.
Organic solvent E (3): Texanol manufactured by Nagase Sangyo Co., Ltd.
Organic solvent E (4): Ethyl diglycol acetate (EDGAC) manufactured by Daicel Corporation
Organic solvent E (5): Propylene glycol monomethyl ether acetate (PGMEA) manufactured by Daicel Corporation
Additive 1: Conductive titanium oxide FT-1000 manufactured by Ishihara Sangyo Co., Ltd.
Additive 2: Anti-settling agent Disparon 4200-10 manufactured by Enomoto Kasei Co., Ltd.
Additive 3: JER828 manufactured by Japan Epoxy Resin Co., Ltd.
Additive 4: Polymerization inhibitor hydroquinone additive 5 manufactured by Nacalai Co., Ltd. 5: Block isocyanate (2): Baksenden BI7960
Additive 6: Oxetane: manufactured by Toagosei Co., Ltd. OXT-121
Curing catalyst: Kyodo Pharmaceutical Co., Ltd. KS1260
Dispersant: Disperbyk-2155 manufactured by Big Chemie Japan Co., Ltd.
Antifoaming agent: Kyoeisha Chemical Co., Ltd. AC300HF

(Synthesis example 1 of photosensitive organic binder resin A (5))
A reaction vessel equipped with a stirrer, a condenser and a thermometer was charged with methyl methacrylate and methacrylic acid in a molar ratio of 0.76: 0.24, dipropylene glycol monomethyl ether as a solvent, and azobisisobutyronitrile as a catalyst. The mixture was stirred at 80 ° C. for 2 to 6 hours under a nitrogen atmosphere to obtain a resin solution. The resin solution was cooled, methylhydroquinone as a polymerization inhibitor, tetrabutylphosphonium bromide as a catalyst, and glycidyl methacrylate was added at 0.12 to 1 mol of the carboxyl group of the resin under the conditions of 95 to 105 ° C. for 16 hours. Addition reaction was carried out at an addition molar ratio of a molar ratio, and the mixture was cooled and taken out to obtain a photosensitive acrylic copolymer resin solution P (1) containing a photopolymerizable functional group and a carboxyl group with a solid content concentration of 48.2 wt%. The obtained resin had an acid value (in terms of solid content) of 1100 eq / ton and Mw of 10,000.

(Synthesis example of photosensitive organic binder resin A (6))
In a reaction vessel equipped with a stirrer, condenser, and thermometer, FHPA (equivalent reaction product of bisphenolfluorene type epoxy resin and acrylic acid (manufactured by Nippon Steel Chemical Co., Ltd., ASF-400 solution: solid content concentration 50 wt%, solid content conversion) Acid value 1.28mgKOH / g) 50% propylene glycol monomethyl ether acetate solution 206.26g (0.17mol), biphenyltetracarboxylic dianhydride 0.085mol, tetrahydrophthalic anhydride 0.085mol, propylene glycol monomethyl ether acetate 26.0g And 0.45 g of triphenylphosphine were added and stirred for 6 hours while heating at 120 to 125 ° C. to obtain a photosensitive ester resin solution P (2) containing a photopolymerizable functional group and a carboxyl group with a solid content concentration of 55.6 wt%. The resulting resin had an acid value (in terms of solid content) of 1850 eq / ton and Mw of 2600.

(Synthesis example of organic binder resin A (7))
In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 700 parts of terephthalic acid, 700 parts of isophthalic acid, 16.9 parts of trimellitic anhydride, 983 parts of ethylene glycol, 154 parts of 2-methyl-1,3-propanediol, The esterification reaction was carried out from 160 ° C. to 230 ° C. over 3 hours under a nitrogen atmosphere at 2 atm. After releasing the pressure, 0.92 part of tetrabutyl titanate was added, and then the pressure inside the system was gradually reduced to 5 mmHg over 20 minutes, and then the pressure was reduced to 260 ° C. for 40 minutes under a vacuum of 0.3 mmHg or less. A condensation reaction was performed. Under a nitrogen stream, the mixture was cooled to 220 ° C., 50.6 parts of trimellitic anhydride was added, and reacted for 30 minutes to obtain a polyester resin. The composition of the obtained copolyester (P-6) was terephthalic acid / isophthalic acid / trimellitic acid // ethylene glycol / 2-methyl-1,3-propanediol = 48/48/4 // 85/15 ( Molar ratio). The acid value of the obtained resin was 250 eq / ton and Mw was 45,000.

Comparative Example 1
As photosensitive organic binder (A), Daicel Ornex Co. (ACA) Z320 (solid content concentration 39 wt%) is 2564 parts (1000 parts as solid part (including 1564 parts dipropylene glycol monomethyl ether as solvent (E)) ), 8,940 parts of spherical silver powder (D50 = 1.5 μm) as the conductive powder (B), 480 parts of PETIA (pentaerythritol triacrylate) manufactured by Daicel Ornex as photopolymerizable compound (C), light 2.5 parts Oxe-01 manufactured by BASF as a polymerization initiator (D), 50 parts Polyflow No. 90 manufactured by Kyoeisha Chemical Co., Ltd. as a leveling agent, Disperbyk 2155 manufactured by BYK Japan Japan Co., Ltd. as a dispersant. And 60 parts of dipropylene glycol monomethyl ether as solvent (E). The mixture was passed through a three-roll kneader and dispersed three times.
Thereafter, the obtained conductive paste was printed in a predetermined pattern on each of the PET substrate and the ITO film (manufactured by Oike Industry Co., Ltd., KH300), and then dried in a hot air dryer at 90 ° C. for 10 minutes. A conductive thin film was obtained. Thereafter, exposure, development, and final drying were performed using the conductive thin film, and basic properties such as specific resistance, adhesion, and pencil hardness were measured, and developability was evaluated. Table 2 shows the evaluation results of paste, paste coating film, and developability.

Comparative Examples 2-12
A photosensitive conductive paste was prepared in the same manner as in Comparative Example 1 with the components and blends shown in Table 2, and the paste was not filtered, or filtered using a filter with an opening larger than 30 μm, and then annealed. A coating film was prepared using a PET film and an ITO film (manufactured by Oike Kogyo Co., Ltd.) as a base material, and the physical properties and developability of the coating film were evaluated in the same manner as in Comparative Example 1. The evaluation results are shown in Table 2. When the conductive paste is not filtered as in 2, or when filtration is performed using a filtration filter having an opening larger than 30 μm, the conductivity between both ends of the fine wires and the insulation between the adjacent fine wires deteriorate, The fine line shape was also bad.
The conductive powder, additive and solvent shown in Table 2 are the same as those in Table 1.

  The photosensitive conductive paste of the present invention gives excellent fine pattern formability by development by removing coarse particles and foreign matters in the paste by paste filtration. In addition, it is possible to provide a conductive thin film that is excellent in wet heat environment reliability and can maintain the durability of the coating film as a conductive thin film. For example, it can be applied to a mobile phone, a notebook computer, an electronic book equipped with a touch panel, etc. It is useful as a conductive paste to be used.

1a, 2a, 3a, 4a: terminal A
1b, 2b, 3b, 4b: Terminal B
1c, 2c, 3c, 4c: terminal C
5: Non-conductive portion (unexposed conductive thin film pattern washed away by development)

Claims (8)

  Containing a photosensitive organic binder (A), a conductive powder (B) having an average particle diameter D50 of 5 μm or less, a photopolymerizable compound (C), a photopolymerization initiator (D), and an organic solvent (E); A photosensitive conductive paste characterized in that a scratch on a grind gauge begins to occur at 10 μm or less. The photosensitive organic binder (A) contains a photosensitive organic binder having an acid value of 500 to 4,000 eq / ton and a weight average molecular weight of 5,000 to 8,000. The photosensitive conductive paste as described. As the photosensitive organic binder (A), a (meth) acrylic copolymer obtained by adding an alicyclic epoxy (meth) acrylate to a part of the carboxyl group of a (meth) acrylic copolymer having a carboxyl group is used. The photosensitive conductive paste according to claim 1, wherein the photosensitive conductive paste is contained.   The electroconductive thin film formed from the photosensitive electrically conductive paste in any one of Claims 1-3.   The conductive thin film according to claim 4, wherein an arithmetic average roughness of the conductive thin film is 0.40 μm or less.   An electric circuit using the conductive thin film according to claim 4 or 5.   A touch panel comprising the electric circuit according to claim 6 as a constituent member. (1) A step of filtering photosensitive conductive paste with a filter having an opening of 30 μm or less,
(2) Next, a step of applying the photosensitive conductive paste on a substrate and drying at a temperature of 110 ° C. or lower,
(3) Next, a step of exposing a part of the applied photosensitive conductive paste,
(4) Next, developing the unexposed area,
(5) The process of drying the exposed part which was not developed at the temperature of 140 degrees C or less The process of said (1)-(5) is included, The manufacturing method of the electroconductive thin film of Claim 4 or 5 characterized by the above-mentioned. .