JP2010153362A - Photosensitive conductive paste, electrode formed using it, plasma display panel, and method for manufacturing photosensitive conductive paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive conductive paste in which a thin film electrode having a superior line shape and denseness is formed, and a plasma display panel in which the electrode is formed by using this photosensitive conductive paste. <P>SOLUTION: This photosensitive conductive paste includes an organic binder, silver powders of which the primary particle size is 1.0 μm or less, the specific surface area is 1.5-2.0 m<SP>2</SP>/g, and the tap density is 2.0-5.0 g/cm<SP>3</SP>, a photo-polymerization monomer, a photo-polymerization initiator, an organic solvent, and a glass frit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides, for example, a photosensitive conductive paste, an electrode, a plasma display panel, and a photosensitive conductive paste used for forming a high-definition electrode circuit on a substrate of a plasma display panel (hereinafter abbreviated as “PDP”). It relates to a manufacturing method.

  In general, as a method of forming a pattern of a conductor such as an electrode (hereinafter referred to as “electrode”) on a printed wiring board or a PDP substrate (hereinafter referred to as “substrate”), a paste in which metal powder is mixed with an organic binder. A screen printing method is used in which an electrode is formed by creating a material and printing the paste material on a substrate using a screen plate. (See, for example, Patent Document 1).

  In recent years, there has been an increasing demand for smaller, thinner, higher density, higher definition, and higher reliability substrate materials. Accordingly, improvement of electrode processing technology is desired. In particular, with respect to the electrode portion of the PDP substrate, unlike the printed wiring board, the electrode is formed on a large PDP substrate exceeding 30 inches, so that the accuracy and high definition of the electrode are desired.

  Here, the above-described screen printing method has an advantage that workability is good at low cost. However, since the accuracy of the printing mask depends on the accuracy of the mask making, the dimensional error of the mask pattern increases as the printing mask becomes larger. For this reason, it is difficult to form a high-definition electrode on a 30-inch or larger PDP substrate by the screen printing method, and the production of a PDP having a high-definition electrode is increasingly technically difficult. Further, in the screen printing method, it is difficult to form an electrode having a line width of 100 μm or less in an industrially stable manner.

  Therefore, recently, as a method for obtaining a finer electrode than the screen printing method, a method of forming an electrode using a photoconductive technique using a photosensitive conductive paste has been proposed (for example, Patent Document 2 and Patent Document 3). Etc.)

  Here, in the photosensitive conductive paste used in the above method, it is necessary to blend a conductive powder at a high concentration in order to ensure the conductivity. And since this conductive powder generally uses a noble metal with good conductivity such as silver, there is a problem that it is difficult to reduce the cost of the photosensitive conductive paste. In particular, when this paste is used for electrode formation of a large-screen PDP, the cost of the paste and a PDP manufactured using the paste is significantly increased in proportion to the size. From the viewpoint of price competition of the PDP, These further cost reductions are desired.

  As a countermeasure for such a demand, it is possible to reduce the amount of the photosensitive conductive paste used for forming the electrode by thinning the electrode. However, there is a problem that when the electrode is thinned, the resistance value of the formed electrode increases.

Japanese Patent Laid-Open No. 10-269848 (Claims) JP-A-11-224531 (Claims) Japanese Patent No. 3520798 (Claims)

The present invention has been made to solve the above-mentioned problems of the prior art, and its main purpose is to have a good line shape and denseness while reducing the amount of silver used as a conductive powder. It is to provide a photosensitive conductive paste capable of forming a thin film electrode.
Another object of the present invention is to provide an electrode and a plasma display panel formed using the conductive paste.
Furthermore, another object of the present invention is to provide a method for producing the photosensitive conductive paste.

In order to achieve the above object, the photosensitive conductive paste of one embodiment of the present invention has the following configuration.
That is, the photosensitive conductive paste of the present invention has an organic binder, a primary particle size of 1.0 μm or less, a specific surface area of 1.5 to 2.0 m ² / g, and a tap density of 2.0 to 5.0 g. This is a photosensitive conductive paste containing silver powder of / cm ³ , a photopolymerization monomer, a photopolymerization initiator, an organic solvent, and glass frit.

  Specifically, the blending amount of the organic solvent is preferably less than 40% by mass with respect to the organic component contained in the photosensitive conductive paste. Here, the organic component refers to an organic compound (including an organometallic compound) blended in the photosensitive conductive paste, specifically, an organic binder, a photopolymerization monomer, a photopolymerization initiator, an organic solvent, Dispersants, stabilizers, etc. are applicable.

  With such a configuration, the photosensitive conductive paste of the present invention can form a thin film electrode having a good line shape and denseness.

  Moreover, specifically, it is preferable that the compounding quantity of the said silver powder is 30-45 mass parts with respect to 100 mass parts of the said photosensitive electrically conductive pastes. With such a configuration, an electrode formed using the photosensitive conductive paste of the present invention can obtain sufficient conductivity without being in a porous state.

  More specifically, the average particle size of the glass frit is preferably 1.5 μm or less. With such a configuration, the photosensitive conductive paste of the present invention undergoes uniform shrinkage during firing, so that the line shape of the electrode to be formed becomes sharp and a dense film electrode can be formed.

  The electrode of the present invention is formed using the photosensitive conductive paste.

Specifically, an electrode formed using the photosensitive conductive paste of the present invention has a film thickness of 1.0 μm or less.
With such a configuration, the electrode of the present invention can reduce the amount of silver used, and can achieve a reduction in cost of the photosensitive conductive paste and a PDP manufactured using the same.

  Moreover, the plasma display panel of this invention is equipped with the said electrode, It is characterized by the above-mentioned.

The method for producing a photosensitive conductive paste according to the present invention comprises preparing a glass slurry by wet dispersion or pulverization of a mixture containing a glass frit, an organic solvent, and a dispersant. The glass slurry, the organic binder, and the primary particle size are Silver powder, photopolymerization monomer, photopolymerization initiator, and organic solvent having a specific surface area of 1.5 to 2.0 m ² / g and a tap density of 2.0 to 5.0 g / cm ³ of 1.0 μm or less And are mixed.
Specifically, the blending amount of the organic solvent (including the organic solvent contained in the glass slurry) is less than 40% by mass with respect to the organic component contained in the photosensitive conductive paste produced by the production method. Is preferred.

  With such a configuration, the photosensitive conductive paste manufactured by the method for manufacturing a photosensitive conductive paste of the present invention can form a thin film electrode having a good line shape and denseness.

  More specifically, the average particle size of the glass frit is preferably 1.5 μm or less. With such a configuration, the photosensitive conductive paste produced by the method for producing a photosensitive conductive paste of the present invention undergoes uniform shrinkage during firing, so that the line shape of the electrode to be formed becomes sharp and a dense film The electrode can be formed.

  The photosensitive conductive paste of the present invention can form a thin film electrode having a good line shape and denseness. Further, by reducing the thickness of the electrode to be formed, the amount of the photosensitive conductive paste used for forming the electrode can be reduced, and further, the amount of silver contained in the conductive paste can be reduced. Thereby, cost reduction of the photosensitive electrically conductive paste and PDP manufactured using this can be achieved.

Hereinafter, although an example of the embodiment of the present invention is explained, the present invention is not limited to this.
In the present specification, the “coating film” refers to a coating film formed using the photosensitive conductive paste of the present invention, and includes those cured by exposure.

The photosensitive conductive paste of this embodiment has a primary particle size of 1.0 μm or less, a specific surface area of 1.5 to 2.0 m ² / g, and a tap density of 2.0 to 5.0 g / cm ³ . It contains silver powder.
Specifically, the blending amount of the silver powder is preferably 30 to 45 parts by mass with respect to 100 parts by mass of the photosensitive conductive paste.
More specifically, the photosensitive conductive paste preferably contains an organic solvent in an amount of less than 40% by mass with respect to the organic component contained in the photosensitive conductive paste.

In addition, the method for producing a photosensitive conductive paste of the present embodiment prepares a glass slurry by wet dispersion or pulverization of a mixture containing a glass frit, an organic solvent, and a dispersant, and the glass slurry, the organic binder, and the primary particle size. Is 1.0 μm or less, specific surface area is 1.5 to 2.0 m ² / g, tap density is 2.0 to 5.0 g / cm ³ , silver powder, photopolymerization monomer, photopolymerization initiator, and organic It is characterized by mixing a solvent.
Specifically, it is preferable that the compounding quantity of the said organic solvent to the photosensitive electrically conductive paste is less than 40 mass% with respect to the organic component contained in the said photosensitive electrically conductive paste.

  With such a configuration, the photosensitive conductive paste manufactured by the photosensitive conductive paste of the present embodiment and the photosensitive conductive paste manufacturing method has a good line shape of the electrode to be formed, and the film thickness is further increased. A thin film of 1.0 μm or less can be formed. Furthermore, an excellent electrode having a dense coating can be formed.

  Examples of the organic binder used in this embodiment include a resin having a carboxyl group. Specifically, both a carboxyl group-containing photosensitive resin having an ethylenic double bond and a carboxyl group-containing resin having no ethylenically unsaturated double bond can be used. Moreover, the following can be mentioned as resin (any of an oligomer and a polymer) which can be used conveniently as an organic binder.

(1) A carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth) acrylic acid and a compound having an unsaturated double bond such as methyl (meth) acrylate.
(2) Glycidyl (meth) acrylate and (meth) acrylic acid for copolymers of unsaturated carboxylic acids such as (meth) acrylic acid and compounds having unsaturated double bonds such as methyl (meth) acrylate A carboxyl group-containing photosensitive resin obtained by adding an ethylenically unsaturated group as a pendant with chloride or the like.
(3) A copolymer of a compound having an epoxy group such as glycidyl (meth) acrylate and an unsaturated double bond and a compound having an unsaturated double bond such as methyl (meth) acrylate is used as a (meth) acrylic compound. A carboxyl group-containing photosensitive resin obtained by reacting a secondary hydroxyl group generated by reacting an unsaturated carboxylic acid such as an acid with a polybasic acid anhydride such as tetrahydrophthalic anhydride.
(4) To a copolymer of an acid anhydride having an unsaturated double bond such as maleic anhydride and a compound having an unsaturated double bond such as styrene, a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, A carboxyl group-containing photosensitive resin obtained by reacting a compound having an unsaturated double bond.
(5) It is obtained by reacting a polybasic acid anhydride such as tetrahydrophthalic anhydride with a secondary hydroxyl group produced by reacting a polyfunctional epoxy compound with an unsaturated carboxylic acid such as (meth) acrylic acid. Carboxyl group-containing photosensitive resin.
(6) An epoxy group of a copolymer of an unsaturated double bond such as methyl (meth) acrylate and a glycidyl (meth) acrylate has an ethylenically unsaturated bond having one carboxyl group in one molecule. A carboxyl group-containing photosensitive resin obtained by reacting an organic acid that does not have a polybasic acid anhydride with a secondary hydroxyl group produced thereby.
(7) A carboxyl group-containing resin obtained by reacting a polybasic acid anhydride with a hydroxyl group-containing polymer such as polyvinyl alcohol.
(8) Unsaturation with an epoxy group such as glycidyl (meth) acrylate and a carboxyl group-containing resin obtained by reacting a polybasic acid anhydride such as tetrahydrophthalic acid anhydride with a hydroxyl group-containing polymer such as polyvinyl alcohol. Examples thereof include a carboxyl group-containing photosensitive resin obtained by further reacting a compound having a double bond. Of these, the resins (1), (2), (3), and (6) are particularly preferably used.

  The term “(meth) acrylate” is a generic term for acrylate, methacrylate, and a mixture thereof, and the same applies to other similar expressions.

  Such carboxyl group-containing photosensitive resins and carboxyl group-containing resins may be used alone or in combination. It is preferable that these compounding quantities are 10-50 mass parts with respect to 100 mass parts of photosensitive electrically conductive paste. When the said compounding quantity is less than 10 mass parts, the distribution of the said resin to the coating film formed using the photosensitive conductive paste of this invention tends to become non-uniform | heterogenous. In this case, it becomes difficult for the coating film to obtain sufficient photocurability and photocuring depth, and patterning by selective exposure and development becomes difficult. On the other hand, when the compounding amount exceeds 50 parts by mass, the electrodes are liable to be warped and the line width is shrunk during firing.

  The resin having a carboxyl group used in the present invention preferably has a weight average molecular weight of 1,000 to 100,000 and an acid value of 50 to 250 mgKOH / g. Further, when a carboxyl group-containing photosensitive resin is used as the resin having a carboxyl group, a resin having a double bond equivalent of 350 to 2,000 g / equivalent, preferably 400 to 1,500 g / equivalent can be suitably used. . When the weight average molecular weight of the resin having a carboxyl group is less than 1,000, it adversely affects the adhesion of the coating film during development. On the other hand, when the said weight average molecular weight exceeds 100,000, it will become easy to produce the image development defect of a coating film. A more preferable range of the weight average molecular weight is 5,000 to 70,000.

  In addition, when the acid value of the resin having a carboxyl group is less than 50 mgKOH / g, the solubility in an alkaline aqueous solution is insufficient and development failure tends to occur. On the other hand, when the acid value exceeds 250 mgKOH / g, the adhesion of the coating film deteriorates and the photocured portion (exposed portion) of the coating film dissolves during development. Furthermore, when a carboxyl group-containing photosensitive resin is used as the resin having a carboxyl group, if the double bond equivalent of the resin is less than 350 g / equivalent, a residue tends to remain during firing. On the other hand, when the double bond equivalent exceeds 2,000 g / equivalent, the work margin during development of the coating film becomes narrow, and a high exposure amount is required during photocuring of the coating film.

  The primary particle size of the silver powder used in this embodiment is 1.0 μm or less. When the primary particle diameter is 1.0 μm or less, shrinkage during firing occurs uniformly, so that the line shape of the electrode becomes sharp and a dense film electrode can be formed. If this primary particle size is larger than 1.0 μm, pinholes and gaps are likely to be formed in the conductive film after firing, and it becomes difficult to obtain sufficient conductivity. There is no restriction | limiting in particular about the minimum of this primary particle size. However, since the silver becomes more expensive as the primary particle size becomes smaller, 0.5 μm or more is preferable from the viewpoint of cost reduction. A more preferable primary particle size is 0.5 to 0.7 μm. In this embodiment, the primary particle size of the silver powder means the average particle size of 10 random silver powders observed at 10,000 times using an electron microscope (SEM).

Moreover, the specific surface area of silver powder is 1.5-2.0 m < ² > / g. When the specific surface area of the silver powder is within this range, the light scattering of the silver powder is small and the curing proceeds sufficiently to the lower part of the coating film, so that peeling does not occur during development of the coating film.

Moreover, the tap density of silver powder is 2.0-5.0 g / cm < ³ >. When the tap density of the silver powder is within this range, a dense coating film with good paste applicability can be obtained. A more preferable tap density is 2.4 to 4.2 g / cm ³ .

  In addition, the silver powder of this embodiment can be used in various shapes such as a spherical shape, a flake shape, and a dendrite shape, but it is preferable to use a spherical shape in consideration of optical characteristics and dispersibility.

  The compounding quantity of the silver powder to the photosensitive electrically conductive paste of this embodiment is 30-45 mass parts with respect to 100 mass parts of the said conductive paste. When the blending amount of the silver powder is less than 30 parts by mass, the fired electrode becomes porous and it is difficult to obtain sufficient conductivity. Moreover, when the said compounding quantity exceeds 45 mass parts, the said electrically conductive paste and PDP manufactured using this will become high-cost.

  The photopolymerizable monomer used in this embodiment is used for promoting photocurability and improving developability of the composition. Photopolymerizable monomers include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, penta Erythritol tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and each methacrylate corresponding to the above acrylate; phthalic acid, adipic acid, maleic acid, itaconic acid, succinic acid, Polybasic acids such as trimellitic acid and terephthalic acid and hydroxyalkyl Meth) mono acrylate -, di -, tri - or more polyester. These are not limited to specific ones, and these can be used alone or in combination of two or more. Among these photopolymerizable monomers, polyfunctional monomers having two or more acryloyl groups or methacryloyl groups in one molecule are preferably used.

  The amount of such a photopolymerizable monomer is appropriately 20 to 100 parts by mass per 100 parts by mass of the organic binder. When the blending amount of the photopolymerizable monomer is less than 20 parts by mass, it becomes difficult to obtain sufficient photocurability of the paste. On the other hand, when the blending amount exceeds 100 parts by mass, photocuring of the surface portion is faster than the deep portion of the coating, and thus uneven curing is likely to occur.

  Specific examples of the photopolymerization initiator used in the present embodiment include benzoin, benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenyl Acetophenones such as acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2- Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl Aminoacetophenones such as 1-butanone; 2- Anthraquinones such as tilanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, etc. Thioxanthones; ketones such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; or xanthones; (2,6-dimethoxybenzoyl) -2,4,4-pentylphosphine oxide, bis (2,4 , 6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl-2,4,6-trimethylbenzoyldiphenylphosphine Phosphine oxide such as sulfonate; various peroxides and the like. These can be used alone or in combination of two or more. Examples of commercially available products include Irgacure 184, Irgacure 819, Irgacure 907, Irgacure 369, Irgacure 379, and Lucilin TPO manufactured by BASF, manufactured by Ciba Specialty Chemicals.

  1-30 mass parts is suitable for 100 mass parts of organic binders, and, as for the compounding quantity of these photoinitiators, Preferably, it is 5-20 mass parts.

  Further, such photopolymerization initiators are tertiary, such as N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine and the like. It can be used in combination with one or more photosensitizers such as amines.

  Furthermore, when a deeper photocuring depth is required, a titanocene photopolymerization initiator (Irgacure 784 manufactured by Ciba Specialty Chemicals Co., Ltd.) that initiates radical polymerization in the visible region, a leuco dye, or the like is a curing aid. Can be used in combination.

  Moreover, a thermal polymerization catalyst can be used in combination with the photopolymerization initiator. This thermal polymerization catalyst is capable of reacting an uncured photopolymerizable monomer contained in the coating film by performing aging at a high temperature for several minutes to about 1 hour. Specifically, a peroxide such as benzoyl peroxide and an azo compound such as isobutyronitrile. As the thermal polymerization catalyst, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis-2,4-divaleronitrile, 1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis-4-cyanovaleric acid, 2-methyl-2,2'-azobispropane Nitrile, 2,4-dimethyl-2,2,2 ′, 2′-azobispentanenitrile, 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2,2 ′, 2′- And azobis (2-methylbutanamide oxime) dihydrochloride. More preferable examples include environmentally friendly non-cyanide and non-halogen type 1,1′-azobis (1-acetoxy-1-phenylethane).

  Specific examples of the organic solvent used in the present embodiment include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methyl cellosolve, carbitol, methylcarbitol, Glycol ethers such as butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, Butyl carbitol acetate, propylene glycol monomethyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoi Esters such as butyrate; Alcohols such as ethanol, propanol, ethylene glycol, propylene glycol, and terpineol; Aliphatic hydrocarbons such as octane and decane; Petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha Is mentioned. These can be used alone or in combination of two or more.

  Such an organic solvent is preferably blended so as to be less than 40% by mass with respect to the organic component contained in the photosensitive conductive paste. When the blending amount of the organic solvent is 40% by mass or more with respect to the organic component, the viscosity of the paste is lowered and the coating property is deteriorated. Moreover, sedimentation etc. generate | occur | produces and the storage stability of a paste falls.

The glass frit used in this embodiment preferably has a glass softening point of 420 to 580 ° C. More preferably, the glass transition point is 360 to 500 ° C. Moreover, it is preferable that an average particle diameter is 0.2-1.0 micrometer. When the average particle size of the glass frit is 1.0 μm or less, shrinkage during firing occurs uniformly, the line shape of the electrode becomes sharp, and a dense film electrode can be formed. Moreover, the thermal expansion coefficient α300 of the glass frit is preferably 60 to 110 × 10 ⁻⁷ .

  As such a glass frit, a material mainly composed of lead oxide, bismuth oxide, zinc oxide, lithium oxide, or alkali borosilicate is preferably used.

As a glass frit mainly composed of lead oxide, the mass percentage based on oxide is 48 to 82% for PbO, 0.5 to 22% for B ₂ O _{3, 3} to 32% for SiO ₂ , Al ₂ O. ₃ is 0 to 12%, BaO is 0 to 15%, TiO ₂ is 0 to 2.5%, Bi ₂ O ₃ is 0 to 25%, and the softening point is 420 to 580 ° C. Glass frit.

Preferable examples of the glass frit containing bismuth oxide as a main component are, based on oxide, mass%, Bi ₂ O ₃ is 6 to 88%, B ₂ O ₃ is 5 to 30%, and SiO ₂ is 5 to 25%. Amorphous glass frit having a composition of Al ₂ O ₃ of 0 to 5%, BaO of 0 to 20%, ZnO of 1 to 20%, and a softening point of 420 to 580 ° C. can be mentioned.

Preferred examples of the glass frit mainly composed of zinc oxide, at a weight percent on the oxide basis, ZnO is 25 to 60%, _{K 2} O there is _{2~15% B 2 O 3 25~45%} , SiO 2 Is an amorphous glass frit having a composition of 1 to 7%, Al ₂ O ₃ of 0 to 10%, BaO of 0 to 20%, MgO of 0 to 10%, and a softening point of 420 to 580 ° C. Can be mentioned.

  The blending amount of such a glass frit is 1 to 30 parts by mass, preferably 1 to 20 parts by mass with respect to 100 parts by mass of the silver powder from the viewpoint of improving the adhesion of the electrode after firing and reducing the resistance value. .

  Furthermore, a dispersant can be added to the photosensitive conductive paste of this embodiment in order to uniformly disperse the glass frit in the paste. A dispersing agent will not be specifically limited if a glass frit can be uniformly disperse | distributed to the said paste, It can also be used 1 type or in mixture of 2 or more types. Dispersants include polycarboxylic acid type polymer surfactants, modified acrylic block copolymers, acrylic copolymers having pigment affinity groups, block copolymers having basic or acidic pigment adsorbing groups, pigments Modified polyalkoxylate having affinity group, combination of polyaminoamide salt and polyester, or combination of polar acid ester and high molecular alcohol, alkyl ammonium salt of acidic polymer, high molecular weight block copolymer having pigment affinity group, special Although a modified urea etc. are mentioned, it is not specifically limited to these.

  Commercially available dispersants (including rheology control agents for preventing sedimentation) that can be used particularly suitably include Modaflow (manufactured by Monsanto), Disperbyk (registered trademark) -101, -103,- 110, -111, -160, -171, -174, -182, -184, -190, -300, -BYK (registered trademark) -P105, -P104, -P104S, -240, -410 (all BIC -Chemie Japan Co., Ltd.).

  In addition, the glass slurry of this embodiment is a wet dispersion (including pulverization) of a mixture containing 40 to 90 parts by weight of glass frit, 10 to 60 parts by weight of an organic solvent, and 0.03 to 10 parts by weight of a dispersant. The same). A preferred embodiment is a glass frit prepared by wet dispersion of a mixture containing 50 to 85 parts by weight of glass frit, 15 to 50 parts by weight of an organic solvent, and 0.1 to 8 parts by weight of a dispersant.

  Examples of the wet disperser used for preparing the glass slurry include a sand mill, a ball mill, a bead mill, and an attritor. Among these, a bead mill is preferable from the viewpoint of productivity and dispersibility. The dispersant may be added at the time of wet dispersion or may be added thereafter. When the glass frit content is high, the viscosity of the glass slurry is also increased. Therefore, it is desirable to add a dispersant having a high viscosity reducing effect during wet dispersion.

  Furthermore, the glass slurry can be subjected to high-definition filtration according to the pulverization degree. In particular, it is preferable that the glass slurry is filtered with a filtration filter having a 98 mass% filtration accuracy of 2 to 40 μm, and preferably 98 mass% filtration accuracy of 5 to 33 μm, and then formed into a paste. Thereby, it is possible to form an electrode having a dense film without occurrence of pinholes or the like. The glass slurry refers to a solution in which glass fine particles are dispersed (or suspended) in a liquid, and includes those in which glass is pulverized during dispersion.

  When a large amount of inorganic powder is blended in the photosensitive conductive paste of this embodiment, the storage stability of the resulting composition is poor, and the coating workability tends to be poor due to gelation and fluidity deterioration. Therefore, in the composition of the present embodiment, in order to improve the storage stability of the composition, a compound having an effect such as complexation with a metal or oxide powder as a component of the inorganic powder, or salt formation with these, It can be added as a stabilizer.

  Stabilizers of this embodiment include various inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, boric acid; formic acid, acetic acid, acetoacetic acid, citric acid, stearic acid, maleic acid, fumaric acid, phthalic acid, benzenesulfonic acid, sulfamine Various organic acids such as acids; phosphoric acid, phosphorous acid, hypophosphorous acid, methyl phosphate, ethyl phosphate, butyl phosphate, phenyl phosphate, ethyl phosphite, diphenyl phosphite, mono (2-methacryloyl) Examples thereof include acids such as various phosphoric acid compounds (inorganic phosphoric acid, organic phosphoric acid) such as oxyethyl) acid phosphate and di (2-methacryloyloxyethyl) acid phosphate. These can be used alone or in combination of two or more. Such a stabilizer is preferably added at a rate of 0.1 to 10 parts by mass per 100 parts by mass of the glass powder and the inorganic powder.

  When boric acid is blended as a stabilizer, it is preferable to use a hydrophobic solvent having a solubility in 100 g of water at 25 ° C. of 20 g or less. When an organic solvent having high solubility in water is used, the water dissolved in the organic solvent ionizes the metal contained in the glass frit and causes gelation.

  Furthermore, additives such as a defoaming / leveling agent such as silicone and acrylic and a silane coupling agent for improving the adhesion of the coating can be blended in the photosensitive conductive paste of this embodiment. In addition, an antioxidant or a thermal polymerization inhibitor for improving thermal stability during storage can be added to the photosensitive conductive paste of the present embodiment.

  The photosensitive conductive paste of this embodiment is applied to a substrate, for example, a glass substrate that serves as a front substrate of a PDP, by a coating method such as a screen printing method, a bar coater, or a blade coater. After application, in order to obtain a touch-drying property, the organic solvent contained in the paste is evaporated by drying it at a temperature of 70 to 120 ° C. for about 5 to 40 minutes in a hot air circulation drying oven, a far infrared drying oven or the like. Thus, a tack-free coating film is formed. When a dry film is formed in advance using the paste, a resin composition layer of the dry film may be laminated on the substrate. After the formation of the coating film, the coating film is selectively exposed, developed and baked to form an electrode.

In the exposure step, contact exposure and non-contact exposure using a negative mask having an exposure pattern are possible. As the exposure light source, a halogen lamp, a high-pressure mercury lamp, a laser beam, a metal halide lamp, a black lamp, an electrodeless lamp, or the like is used. The exposure amount is preferably about 100 to 800 mJ / cm ² .

  In the development process, a spray method, an immersion method, or the like is used. Developers include aqueous alkali metal solutions such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and sodium silicate, and aqueous amine solutions such as monoethanolamine, diethanolamine and triethanolamine, especially about 1.5% by mass or less. A dilute alkaline aqueous solution having a concentration of 5 is preferably used. In addition, as a developing solution, the carboxyl group of the resin which has a carboxyl group contained in a coating film should just be saponified, and an unhardened part (unexposed part) should just be removed, and it is limited to the above developing solutions. It is not a thing. In addition, after the development, it is preferable to wash the substrate and neutralize the acid in order to remove unnecessary developer.

  In the baking step, the substrate after development is subjected to heat treatment at about 400 to 600 ° C. in an air atmosphere or a nitrogen atmosphere to form an electrode. In addition, it is preferable to set the temperature increase rate at this time to 20 degrees C / min or less.

  Hereinafter, the present embodiment will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples.

(Synthesis of organic binder)
In a flask equipped with a thermometer, stirrer, dropping funnel, and reflux condenser, methyl methacrylate and methacrylic acid are charged in a molar ratio of 0.76: 0.24, and dipropylene glycol monomethyl ether as a solvent and azo as a catalyst. Bisisobutyronitrile was added, and these were stirred at 80 ° C. for 2 to 6 hours under a nitrogen atmosphere to obtain a resin solution. The resin solution was cooled, methylhydroquinone was used as a polymerization inhibitor, tetrabutylphosphonium bromide was used as a catalyst, and glycidyl methacrylate was further added at 95 to 105 ° C. for 16 hours with respect to 1 mol of the carboxyl group of the resin. The addition reaction was carried out at an addition molar ratio of 0.12 mol. These were taken out after cooling to obtain an organic binder A. This organic binder A had a weight average molecular weight of about 10,000, a solid content acid value of 59 mgKOH / g, and a double bond equivalent of 950. In addition, the weight average molecular weight of the binder A is a high speed obtained by connecting three pumps LC-6AD manufactured by Shimadzu Corporation and columns Shodex (registered trademark) KF-804, KF-803, and KF-802 manufactured by Showa Denko K.K. Measured by liquid chromatography.

  Using this organic binder A, each component was blended at the composition ratio shown in Table 1, and after stirring with a stirrer, these were kneaded using a three-roll mill to form a paste. Examples 1 to 6 and Each photosensitive conductive paste of Comparative Examples 1 and 2 was prepared. Moreover, the unit of the compounding quantity of each component shown in Table 1 is a mass part.

As the low melting point glass frit, Bi ₂ O ₃ 50%, B ₂ O ₃ 16%, ZnO 14%, SiO ₂ 2%, BaO 18%, thermal expansion coefficient α300 = 86 × 10 ⁻⁷ / ° C., glass softening The one with a point of 501 ° C. was used.

The glass frit was pulverized by a jet mill and measured with a Horiba laser diffraction / scattering particle size distribution analyzer LA-920. The average particle size was 1.3 μm.

(Ag powder)
In this example, Ag powders A to E having different specific surface areas, tap densities, and primary particle sizes shown in Table 2 were used.

(Specimen creation)
Each photosensitive conductive paste for evaluation was applied on the entire surface of a glass substrate using a 300-mesh polyester screen, and then dried in an IR drying oven at 100 ° C. for 20 minutes to provide a touch-drying property. A good coating film was formed. Next, after using a short arc lamp as a light source and pattern exposure of the dry coating film so that the integrated light amount on the dry coating film becomes 300 mJ / cm ² through a negative mask, this was treated with 0.4% by mass of carbonic acid. Development was carried out using an aqueous soda solution, followed by washing with water. And the said board | substrate was baked at 590 degreeC for 10 minute (s) in air atmosphere, and each test piece in which the electrode was formed was created. These evaluation methods are as follows.

(Line shape and denseness);
The defect of the electrode having a width of 100 μm formed by the test piece preparation method was evaluated by microscopic observation.
In the case of good, it was marked as ◯ and in the case of NG, it was marked as x.

(Resistance value);
A test piece having an electrode of 0.4 × 10 cm was prepared by the above test piece preparation method, and the specific resistance value was calculated from the resistance value and film thickness of the formed electrode.
Resistance measurement: Measured with a milliohm high tester.

(Storage stability);
Each of the photosensitive conductive pastes of Examples 1 to 6 and Comparative Example 1 was allowed to stand for 7 days at 25 ° C., and the subsequent sedimentation condition was observed.
No sedimentation was marked with ◯, and sedimentation was marked with ×.

The evaluation results are shown in Table 2.

  As is clear from Examples 1 to 6 and Comparative Example 1 shown in Table 2, according to the photosensitive conductive paste of this embodiment, the line shape, resistance value, and denseness are good, and the film thickness is 1 It was confirmed that a thin film electrode of 0.0 μm or less could be formed.

Claims (6)

An organic binder,
A silver powder having a primary particle size of 1.0 μm or less, a specific surface area of 1.5 to 2.0 m ² / g, and a tap density of 2.0 to 5.0 g / cm ³ ;
A photopolymerizable monomer;
A photopolymerization initiator;
An organic solvent,
A photosensitive conductive paste comprising glass frit.   The photosensitive conductive paste according to claim 1, wherein the amount of the silver powder is 30 to 45 parts by mass with respect to 100 parts by mass of the photosensitive conductive paste.   An electrode formed using the photosensitive conductive paste according to claim 1.   The electrode according to claim 3, wherein a film thickness to be formed is 1.0 μm or less.   A plasma display panel comprising the electrode according to claim 3. A glass slurry is prepared by wet dispersion or pulverization of a mixture containing glass frit, an organic solvent and a dispersant,
A silver powder having a primary particle size of 1.0 μm or less, a specific surface area of 1.5 to 2.0 m ² / g and a tap density of 2.0 to 5.0 g / cm ³ ; A method for producing a photosensitive conductive paste, comprising mixing a photopolymerization monomer, a photopolymerization initiator, and an organic solvent.