WO2005091071A1

WO2005091071A1 - Photosensitive insulative paste composition and photosensitive film using the same

Info

Publication number: WO2005091071A1
Application number: PCT/JP2005/004888
Authority: WO
Inventors: Kiminori Oshio; Ryuma Mizusawa; Akira Kumazawa; Hitoshi Setsuda; Hiroyuki Obiya
Original assignee: Tokyo Ohka Kogyo Co., Ltd.
Priority date: 2004-03-22
Filing date: 2005-03-14
Publication date: 2005-09-29
Also published as: JP2005266663A; TW200602807A; CN1934496B; KR20070007107A; TWI311688B; CN1934496A; JP4282518B2; KR100868550B1

Abstract

A photosensitive insulative paste composition that can be developed in an alkaline developer or water and can be used to form a thick but still highly sensitive layer and, thus, high-precision patterns. The photosensitive insulative paste composition contains an organic component and an inorganic powder and the organic component comprises (A) a water-soluble cellulose derivative, (B) a hydroxyl-containing acrylic resin having a molecular weight of 20000 or less, (C) a photopolymerizable monomer, and (D) a photopolymerization initiator.

Description

DESCRIPTION

PHOTOSENSITIVE INSULATIVE PASTE COMPOSITION AND PHOTOSENSITIVE FILM USING THE SAME

TECHNICAL FIELD The present invention relates to photosensitive insulative paste compositions and photosensitive films using the same. More particularly, the present invention relates to a photosensitive insulative paste composition that has a sensitivity high enough to ensure high-precision pattern formation even in thick layers and includes an inorganic powder and an organic component that is highly resistant to developer. The invention also relates to a photosensitive film using such a photosensitive insulative paste composition.

BACKGROUND ART Technigues such as screen-printing and photolithography have been traditionally used in the production of structural components of thick multi-layered circuits and various display panels. In screen-printing, a desired pattern is screen-printed on a substrate using a light-curable insulative paste containing inorganic particles. In photolithography, a light-curable insulative paste composition applied to a substrate is irradiated with an active ray, such as UV ray, through a photomask to develop a desired pattern on the substrate. Of different types of display panels, plasma display panels (referred to simply as "PDPs," hereinafter) have a relatively simple construction and are thus suitable for large displays. PDPs are emissive devices that can display not just high-quality images but high-quality images in color, Because of these advantageous features, PDPs have attracted significant attention and various proposals have been made in an effort to develop larger plasma displays that can display finer images . A PDP comprises two opposing substrates, between which numerous display cells are defined by insulative barrier ribs. Each cell serves as a picture element and contains a fluorescent substance, which emits light upon exposure to UV radiation emitted by plasma. Electrodes, resistors, dielectrics, and other components that are required to generate plasma are placed on the substrate or within the cells. To construct a high-precision PDP, its components, including barrier ribs, electrodes, resistors, dielectrics, fluorescent substances, color filters, and black matrices, need to be precisely constructed (These components are collectively termed as "barrier ribs or the like," hereinafter) . To this end, the patterns to form the barrier ribs or the like should also be formed precisely. In conventional screen-printing techniques, predetermined patterns of a paste composition are printed one on top of another to form a multi-layered pattern. Accurately aligning these patterns to form a high-precision barrier is difficult. Photolithography techniques also have drawbacks: the sensitivity of the thick layer of the film material to form barrier ribs or the like tends to decrease along the depth. This also makes it difficult to form high- precision patterns. In addition, photolithography requires costly organic solvents, such as trichloroethane , as a developer. This adds to the production cost. These organic solvents also cause environmental pollution and are harmful to human health. To address these problems associated with the development process using organic solvents, a light-curable insulative paste composition that can be developed in an aqueous solution has been proposed. This composition contains a water-soluble cellulose such as methyl cellulose, a photopolymerizable monomer, a photopolymerization initiator, and an inorganic powder (See, for example, Patent Document 1 (Japanese Patent Laid-Open Publication No. Sho 63-265238)). However, this composition is not sufficiently resistant to developer. Thus, a photosensitive insulative paste composition has been proposed that can solve this problem, as well as the problem of inaccurate formation of barrier ribs in screen-printing, which is caused by the dissolving image areas and misalignment of image areas. This composition contains a water-soluble cellulose derivative, a photopolymerizable monomer, a hydroxyl-containing acrylic resin, a photopolymerization initiator, and an inorganic powder (See, for example, Patent Document 2 (Japanese Patent Laid-Open Publication No. 2002-328470)).

DISCLOSURE OF THE INVENTION The photosensitive insulative paste composition described in Patent Document 2, however, forms a residue during the development process if it contains the hydroxyl- containing hydrophobic acrylic resin in 50 parts by weight or larger amounts with respect to the combined amount (= 100 parts by weight) of the water-soluble cellulose derivative and the hydroxyl-containing hydrophobic acrylic resin. The acrylic resin is added to make the composition more resistant to the developer. This residue interferes with the development process. In view of the current state of the art, the present inventors have put a significant effort in finding ways to solve the aforementioned problems. The effort ultimately led to the finding that, as long as the hydroxyl-containing acrylic resin has a molecular weight not exceeding 20000, the composition does not impede the development process even if it contains 90 to 50 parts by weight of the hydroxyl- containing acrylic resin (with respect to the combined amount (= 100 parts by weight) of the water-soluble cellulose derivative and the hydroxyl-containing acrylic resin) and the developer resistance of the composition can be improved by adjusting the amount of the hydroxyl-containing acrylic resin to 50 parts by weight or larger amounts (with respect to the combined amount (= 100 parts by weight) of the water-soluble cellulose derivative and the hydroxyl-containing acrylic resin) . The present invention is based on this finding. It is thus an objective of the present invention to provide a photosensitive insulative paste composition that can be developed in an alkaline developer or water even if it contains a substantial amount of the hydrophobic resin component and that can form a thick but still highly sensitive layer of the film material and are thus suitable for high-precision patterns. Another objective of the present invention is to provide a photosensitive film using such a photosensitive insulative paste composition. The photosensitive insulative paste composition in accordance with the present invention contains an organic component and an inorganic powder. The organic component comprises (A) a water-soluble cellulose derivative, (B) a hydroxyl-containing acrylic resin having a molecular weight of 20000 or less, (C) a photopolymerizable monomer, and (D) a photopolymerization initiator. Preferably, the photosensitive insulative paste composition contains the component (A) and the component (B) in respective amounts of 10 to 50 parts by weight and 90 to 50 parts by weight with respect to the combined amount (= 100 parts by weight) of the component (A) and the component (B) in the organic component. Preferably, the inorganic powder for use in the photosensitive insulative paste composition of the present invention is a glass powder and the composition contains the component (A) and the component (C) in respective amounts of 10 to 50 parts by weight and 90 to 50 parts by weight with respect to^' the combined amount (= 100 parts by weight) of the component (A) and the component (C) in the organic component. Preferably, the photosensitive insulative paste composition of the present invention contains the organic component and the inorganic powder in respective amounts of 5 to 35 parts and 95 to 65 parts by weight with respect to the combined amount (= 100 parts by weight) of the organic component and the inorganic powder. The photosensitive film of the present invention is characterized in that a layer of the above-described photosensitive insulative paste composition is formed on a supporting film. The photosensitive insulative paste composition of the present invention exhibits superior performance when used to develop high-precision patterns in water or an alkaline developer: the composition can be used to form thick but still highly sensitive high-precision insulator patterns. Accordingly, the photosensitive insulative paste composition of the present invention enables low cost production of high- precision PDPs and is therefore of significant industrial value.

BEST MODE FOR CARRYING OUT THE INVENTION Exemplary embodiments of the present invention will now be described. The photosensitive insulative paste composition of the present invention contains an organic component and an inorganic powder. The organic component comprises (A) a water-soluble cellulose derivative, (B) a hydroxyl-containing acrylic resin with a molecular weight of 20000 or less, (C) a photopolymerizable monomer and (D) a photopolymerization initiator . Containing the water-soluble cellulose derivative to act as a binder resin, the photosensitive insulative paste composition of the present invention shows a higher transmittance to UV-ray, excimer laser, X-ray, electron beam, and other active rays and exhibits a higher developer resistance than conventional acrylic resin-based photosensitive insulative paste compositions. For this reason, the composition of the present invention enables the formation of highly accurate patterns . The photosensitive insulative paste composition of the present invention uses the hydroxyl-containing acrylic resin with a molecular weight of 20000 or less to act as the component (B) , so that it does not interfere with the development process even if it contains 50 parts by weight or more of the component (B) with respect to the combined amount (= 100 parts by weight, referred to as "total amount of the resin components," hereinafter) of the water-soluble cellulose derivative and the hydroxyl-containing acrylic resin. Also, the paste composition can exhibit an improved developability by adjusting the amount of the component (B) , a hydrophobic resin, to 50 parts by weight or larger amounts with respect to the total amount (= 100 parts by weight) of the resin components. The water-soluble cellulose derivative to serve as the component (A) may be any known water-soluble cellulose derivative, including carboxymethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose , ethylhydroxyethylcellulose , carboxymethylethylcellulose , and hydroxypropylmethylcellulose . These cellulose derivatives may be used either individually or as a mixture of two or more derivatives . The hydroxyl-containing acrylic resin to serve as the component (B) typically has a molecular weight of 20000 or less, preferably from 5000 to 15000, and more preferably from 8000 to 12000. If the molecular weight of the component (B) exceeds 20000 and the amount of the hydroxyl-containing acrylic resin is 50 parts by weight or larger with respect to the combined amount (= 100 parts by weight) of the water- soluble cellulose derivative and the hydroxyl-containing acrylic resin, then the developability of the composition may be reduced and an unwanted residue may be formed. The hydroxyl-containing acrylic resin may be a copolymer obtained by polymerization of a hydroxyl-containing monomer to serve as the principal copolymerizable monomer. If necessary, other monomers that can copolymerize with the hydroxyl-containing monomer may be used. Preferred examples of the hydroxyl-containing monomer are monoesters formed in the reaction of an acrylic acid or a methacrylic acid with a monoalcohol having 1 to 20 carbon atoms, including hydroxymethylacrylate , hydroxylmethylmethacrylate, 2-hydroxyethylacrylate, 2- hydroxyethylmethacrylate, 2-hydroxypropylacrylate , 2- hydroxypropylmethacrylate, 3-hydroxypropylacrylate , 3- hydroxypropylmethacrylate , 2-hydroxybutylacrylate , 2- hydroxybutylmethacrylate , 3-hydroxybutylacrylate , 3- hydroxybutylmethacrylate , 4-hydroxybutylacrylate , and 4- hydroxybutylmethacrylate . Other preferred examples of the hydroxyl-containing monomer include monoesters formed in the reaction of an acrylic acid or a methacrylic acid with a glycol having 1 to 10 carbon atoms, and epoxy ester compounds, including glycerol acrylate, glycerol methacrylate, dipentaerythritol

monoacrylate, dipentaerythritol monomethacrylate, ε- caprolactone-modified hydroxyethyl acrylate, ε-caprolactone- modified hydroxyethyl methacrylate, and 2-hydroxy-3-

phenoxypropylacrylate . Preferred examples of other monomers that can copolymerize with the hydroxyl-containing monomer include α,β-unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, citraconic acid, maleic acid, and fumaric acid, and anhydrides and half-esterified products

thereof; esters of α,β-unsaturated carboxylic acids, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, sec-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, 2 , 2 , 2-trifluoromethyl acrylate, and 2 , 2 , 2-trifluoromethyl methacrylate; and

styrenes, such as styrene, α-methylstyrene , and p- vinyltoluene . Other examples include acrylonitrile , methacrylonitrile , acrylamide, methacrylamide , vinyl acetate, glycidyl acrylate, and glycidyl methacrylate. These compounds may be used either individually or as a mixture of two or more compounds . The photosensitive insulative paste composition of the present invention preferably contains the hydroxyl-containing acrylic resin in an amount of 50 to 90 parts by weight, more preferably 60 to 80 parts by weight, and still more preferably 65 to 75 parts by weight, with respect to the total amounts of the resin components (= 100 parts by weight) . If the amount of the hydroxyl-containing, acrylic resin component does not fall within the specified range, then the required accuracy may not be achieved in the resulting patterns: The hydroxyl-containing acrylic resin in amounts of less than 50 parts by weight may lead to a reduced developer resistance, whereas the resin in amounts of more than 90 parts by weight tends to result in a reduced developability and the formation of an unwanted residue during the development process. For instance, the photopolymerizable monomer in amounts of less than 50 parts by weight may lead to insufficient photopolymerization, which in turn may result in the image area dissolving during the development and, thus, a failure in image^' formation. In comparison, the photopolymerizable monomer in amounts of more than 90 parts by weight may lead to a reduced resolution of fine images . The photopolymerizable monomer to serve as the component (C) may be any known photopolymerizable monomer, including, but not limited to, ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolethane triacrylate, tri ethylolethane trimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate , pentaerythritol tetramethacrylate, dipentaerythritol tetraacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol pentaacrylate , dipentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate , glycerol acrylate, glycerol methacrylate, and Cardo-type epoxy diacrylate, as well as fumaric acid esters, itaconic acid esters and maleic acid esters that are obtained by replacing (meth) acrylate of the above-listed compounds with fumarate, itaconate and maleate, respectively. The photopolymerization initiator to serve as the component (D) may be any common photopolymerization initiator, including benzophenones , benzoins, benzoin alkyl ethers, acetophenones , aminoacetophenones , benzyls, benzyl alkyl ketals, anthraquinones , ketals, and thioxanthones . Specific examples may include 2 , -bis-trichloromethyl-6- (3-bromo-4- methoxy)phenyl-s-triazine, 2 ,4-bis-trichloromethyl-6- (2- bromo-4-methoxy) phenyl-s-triazine , 2 , 4-bis-trichloromethyl-6- (3-bromo-4-methoxy) styrylphenyl-s-triazine, 2,4-bis- trichloromethyl-6- (2-bromo-4-methoxy) styrylphenyl-s-triazine,

2 , 4 , 6-trimethylbenzoyldiphenyl phosphine oxide, 1- [4-(2- hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-l-propane-l-one, 2 , 4-diethylthioxanthone , 2 , -dimethylthioxanthone , 2- chlorothioxanthone, l-chloro-4-propoxythioxanthone, 3,3- dimethyl-4-methoxybenzophenone, benzophenone , l-(4- isopropylphenyl) -2-hydroxy-2-methylpropane-l-one, 1- (4- dodecylphenyl) -2-hydroxy-2-methylpropane-l-one , 4-benzoyl-4 ' - methyldimethylsulfide , 4-dimethylaminobenzoate, methyl 4- dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, butyl

4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2-isoamyl 4-dimethylaminobenzoate, 2 ,2-diethoxyacetophenone,

benzyldimethylketal , benzyl-β-methoxyethyl acetal , 1-phenyl- 1 , 2-propanedione-2- (o-ethoxycarbonyl) oxime, methyl o- benzoylbenzoate, bis (4-dimethylaminophenyl) ketone , 4,4'- bisdiethylaminobenzophenone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, p- dimethylaminoacetophenone , p-tert-butyltrichloroacetophenone , p-tert-butyldichloroacetophenone, thioxanthone, 2- methylthioxanthone, 2-isopropylthioxanthone , dibensosuberone , ,α-dichloro-4-phenoxyacetophenone, pentyl-4- dimethylaminobenzoate, and 2- (o-chlorophenyl) -4 , 5-diphenyl imidazolyl dimer . These compounds may be used either individually or as a mixture or more than two compounds . The photopolymerization initiator is preferably used in an amount in the range of 0.1 to 10 parts by weight, and more preferably in the range of 0.2 to 5 parts by weight, with respect to the combined amount {- 100 parts by weight) of the water-soluble cellulose derivative and the photopolymerizable monomer. The photopolymerization initiator in amounts of less than 0.1 parts by weight may lead to a decreased curability, whereas the photopolymerization initiator, when contained in amounts of more than 10 parts by weight, may absorb light before the light reaches the bottom, resulting in insufficient curing there. In addition to the components (A) through (D) , the photosensitive insulative paste composition of the present invention may contain optional additives, such as UV absorbers, sensitizers, sensitizer aids, polymerization inhibitors, plasticizers , thickeners, organic solvents, dispersants , anti-foaming agents, inorganic or organic suspending agents . The sensitizer is added for the purpose of increasing the sensitivity. Specific examples of the sensitizer include 2 , -diethylthioxanthone, isopropylthioxanthone , 2,3-bis(4- diethylaminobenzal) cyclopentanone , 2 , 6-bis (.4- dimethylaminobenzal) cyclohexanone, 2 , β-bis (4- dimethylaminobenzal) -4-methylcyclohexanone , Michler's ketone , , 4-bis (diethylamino) -benzophenone, 4,4- bis (dimethylamino) chalcone, 4 , 4-bis (diethylamino) chalcone , p- dimethylaminocinnamylidene indanone, p- dimethylaminobenzylideneindanone, 2- (p- dimethylaminophenylvinylene) -isonaphthothiazole, 1,3-bis (4- dimethylaminobenzal) acetone, 1 , 3-carbonyl-bis (4- diethylaminobenzal) acetone , 3 , 3-carbonyl-bis (7- diethylaminocoumarin) , N-phenyl-N-ethylethanolamine, N- phenylethanolamine , N-tolyldiethanolamine , N- phenylethanolamine, isoamyl dimethylaminobenzoate, isoa yl diethylaminobenzoate , 3-phenyl-5-benzoylthiotetrazole , and 1- phenyl-5-ethoxycarbonylthiotetrazole. These sensitizers may be used either individually or as a mixture of two or more. The polymerization inhibitor may be added for the purpose of increasing the heat stability during storage. Specific examples of the polymerization inhibitor may includehydroquinone, hydroquinone monoesters, N-nitrosodiphenylamine, phenothiazine, p-t-butylcatechol , N-phenylnaphthylamine , 2,6- di-t-butyl-p-methylphenol, chloranil, and pyrogallol. The plasticizer may be added for the purpose of improving the conformity to the substrate. Specific examples . of the plasticizer may include esters of phthalic acid such as dibutyl phthalate (DBP) , dioctyl phthalate (DOP) , and dicyclohexyl phthalate, as well as polyethylene glycol, glycerol, and dibutyl tartrate . The anti-foa ing agent serves to prevent formation of bubbles in the paste or the film, which can otherwise lead to formation of pores after baking. Specific examples of the anti-foaming agent may include those based on alkylene glycols, such as polyethylene glycols (molecular weight = 400 to 800), silicones, or higher alcohols. The inorganic powder for use in the photosensitive insulative paste composition of the present invention may be any inorganic powder that is transparent enough to the light source used. Examples thereof may include glass, ceramic (e.g., cordierite) , and metal powders. More specific examples thereof may be powders of lead borosilicate glass, zinc borosilicate glass, and bismuth borosilicate glass, such as PbO-Si0₂ glass, PbO-B₂0₃-Si0₂ glass, ZnO-Si0₂ glass, ZnO- B₂0₃-Si0₂ glass, BiO-Si0₂ glass, and BiO-B₂0₃-Si0₂ glass; powders of oxides of Na, K, Mg, Ca, Ba, Ti , Zr, and Al , such as cobalt oxide, iron oxide, chromium oxide, nickel oxide, copper oxide, manganese oxide, neodymium oxide, vanadium oxide, cerium oxide, Tipaque Yellow, cadmium oxide, ruthenium oxide, silica, magnesia, and spinel; powders of fluorescent substances, such as ZnO:Zn, Zn₃ (P0 ) ₂ :Mn, Y₂Si0₅:Ce, CaW0 :Pb, BaMgAl₁₄0₂₃ : Eu , ZnS: (Ag, Cd) , Y₂0₃:Eu, Y₂Si0₅:Eu, Y₃Al₅0₁₂:Eu, YB0₃:Eu, (Y, Gd)B0₃:Eu, GdB0₃:Eu, ScB0₃:Eu, LuB0₃:Eu, Zn₂Si0₄:Mn, BaAlι₂0ι₉:Mn, SrAlι₃0ι₉ :Mn, CaAlι₂0ι₉ :Mn, YB0₃:Tb, BaMgAl₁₄0₂₃:Mn, LuB0₃ : Tb , GdB0:Tb, ScB0₃:Tb, Sr₆Si₃0₃Cl₄ :Eu, ' ZnS:(Cu, Al) , ZnS:Ag, Y₂0₂S:Eu, ZnS:Zn, (Y, Cd)B0₃:Eu and BaMgAlι₂0₂₃.^*Eu; and powders of metals, such as iron, nickel, palladium, tungsten, copper, aluminum, silver, gold, and platinum. Of these, glass powders and ceramic powders are particularly preferred because of their high transparency. Glass powders (glass frits) provide most significant effect. It is preferred that the inorganic powder do not contain silicon oxide, aluminum oxide, or titanium oxide since these compounds make the inorganic powder opaque and reduce light transmittance of the inorganic powder. The inorganic powder preferably has an average particle size of 0.5 to lOμm, and more preferably 1 to 8μm, though the size may vary depending on the shape of the patterns to be formed. The inorganic powder larger than lOμm in average particle size can result in the formation of rough surfaces upon formation of high-precision patterns, whereas the inorganic powder smaller than 0.5μm in average particle size scatters light and thus prevents light from penetrating down to the bottom. The inorganic powder may have a variety of shapes, such as spherical, block-like, flake-like or dendrite-like shape, and may be provided in one or combination of these shapes. The inorganic powder may contain not only black powder, but also inorganic pigments of different colors, such as red, blue, and green pigments. The photosensitive insulative paste composition containing such pigments can be used to form patterns in different colors and may thus be suitable for the production of color filters or other components of the plasma display panels. The inorganic powder may be a mixture of a plurality of sorts of fine particles, each sort of particles having different physical properties. By using glass powders or ceramic powders with different heat- softening points, the contraction upon baking can be minimized. These inorganic powders may be mixed in a proper combination of shapes and physical properties that suits the required properties of the barrier ribs or the,like.

Having an average particle size of less than lOμm (0.5 to lOμm) , the inorganic powder may be surface-treated, as long as the properties of the inorganic powder are not impaired, with an organic acid, inorganic acid, silane- coupling agent, titanate-based coupling agent, aluminum-based coupling agent, surfactant, or other surface-treating agents to prevent secondary aggregation and facilitate dispersion of the powder. Specifically, the surface treatment may be carried out as follows: the surface-treating agent is first dissolved in an organic solvent or water. The inorganic powder is then added to the solution and the mixture is stirred. Subsequently, the solvent is evaporated and the

residue is heated at approximately 50 to 200°C for over 2 hours. Alternatively, the surface-treating agent may be added when the photosensitive composition is formed into a paste . The respective proportions of the organic component and the inorganic powder in the photosensitive insulative paste composition of the present invention may typically be in the ranges of from 5 to 35 parts and from 95 to 65 parts by weight, preferably in the ranges of from 10 to 30 parts and from 90 to 70 parts by weight, and more preferably in the ranges of from 15 to 25 parts and from 85 to 75 parts by weight, with respect to the total amount (= 100 parts by weight) of the photosensitive insulative paste composition. If the amount of the organic component is less than 5 parts by weight, then insufficient photopolymerization may result. This may cause the image area to dissolve during the development, leading to a failure in image formation. In comparison, if the amount of the organic component is more than 35 parts by weight, then the resulting patterns may come off upon baking. The photosensitive insulative paste composition may be prepared by dissolving or dispersing the components in a solvent. The solvent used for this purpose may be any solvent as long as it shows a high affinity to the inorganic powder, can dissolve the organic component well, can impart a proper viscosity to the photosensitive insulative paste composition, and can readily be evaporated. Specific examples of such solvents may include ketones, such as diethyl ketone , methyl butyl ketone , dipropyl ketone, and Cyclohexanone; alcohols, such as n-pentanol , 4-methyl-2- pentanol, cyclohexanol , and diacetonealcohol ; ether alcohols, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether; saturated aliphatic monocarboxylic acid alkylesters, such as n-butyl acetate, and amyl acetate; lactic esters, such as ethyl lactate and n- butyl lactate; and ether esters, such as methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol ' monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl 3-ethoxypropionate, 2-methoxybutyl acetate, 3- methoxybutyl acetate, 4-methoxybutyl acetate, 2-methyl-3- methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3- ethyl-3-methoxybutyl acetate, 2-ethoxybutyl acetate, 4- ethoxybutyl acetate, 4-propoxybutyl acetate, and 2- methoxypentyl acetate. These solvents may be used either individually or in combination of two or more solvents. In order to maintain the viscosity of the photosensitive insulative paste composition in a preferable range, the amount of the solvent used is preferably 300 parts by weight or less, more preferably 10 to 70 parts by weight, and most preferably 25 to 35 parts by weight, with respect to the total amount (= 100 parts by weight) of the organic component and the inorganic powder. Depending on its intended applications, the photosensitive insulative paste composition of the present invention may be applied to the substrate either as a liquid or by screen-printing or various other techniques. In applications that require high-precision processing, such as the barrier ribs of PDPs, the composition is preferably applied as a photosensitive film. In this manner, the accuracy of the formed patterns can be significantly improved and a barrier ribs or the like having a high accuracy may be obtained thereby. The photosensitive film may be formed by applying, to a supporting film, the photosensitive paste composition of the present invention and then drying the film

to obtain a film having a thickness of 10 to 100 μm. For example, the support film used for this purpose may be a 15

to 125μm-thick flexible film made of a synthetic resin, such as polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, and polyvinyl chloride. If necessary, the supporting film may be treated with a releasing agent to facilitate transfer of the film. The composition may be applied to the supporting film by means of an applicator, a bar coater, a wire bar coater, a roll coater, or a curtain flow coater. In particular, roll coaters can be used to effectively^' form uniform and thick films and are thus preferred. A protective film may be applied to the photosensitive film for protecting the photosensitive paste composition when the photosensitive film is not in use. The protective film used for this purpose may be an approximately

15 to 125μm-thick silicone-coated or silicone-baked film made of polyethylene terephthalate, polypropylene, or polyethylene. Subsequently, the method for forming desired patterns using the photosensitive insulative paste composition of the present invention will be described. The photosensitive insulative paste composition is first applied to a substrate by a coating or transfer technique to form a layer. An active ray, such as UV-ray, exci er laser, X-ray, and electron beam, is then irradiated onto the composition layer through a mask to expose an image. The exposed image is then developed in an alkaline developer or water. Unexposed areas will dissolve in the developer, leaving a pattern on the substrate. When necessary, the patterned layer is baked. Alternatively, the entire surface of the layer of the photosensitive insulative paste composition may be exposed without masking. In such a case, a pattern is formed without carrying out the developing process. When necessary, the substrate is then baked. When it is desired to form high- precision patterns, the photosensitive film is first stripped of the protective layer and the photosensitive insulative paste composition layer is transferred onto the substrate, forming a layer. The layer is exposed with or without masking and is stripped of the supporting film. The layer exposed with masking is developed to form a pattern, while the layer exposed with no masking is cured without being subjected to the development process and is baked when necessary. The substrate' may be a glass substrate, a glass substrate with an electrode such as a bus electrode formed on it, or a ceramic substrate. In transferring the photosensitive insulative paste composition layer , the composition layer, while held in contact with the substrate surface, is heat-pressed using, for example, a hot roll laminator. The heat-pressing is preferably carried out at a roll pressure of 1 to 5kg/cm² and at a press speed of 0.1 to lO.Om/min with the surface temperature of the substrate

raised to 80 to 140°C. The substrate may be preheated to a temperature of 40 to 100°C. The radiation emitter used to expose the paste composition may be a UV-emitter commonly used in photolithography or an exposure device used in the production of semiconductors and liquid crystal displays ( LCDs ) . The alkaline components of the alkaline developer used in the development process may include hydroxides, carbonates, bicarbonates , phosphates, and pyrophosphates of alkali metals, such as lithium, sodium, and potassium; primary amines, such as benzyla ine and butylamine; secondary amines, such as dimethylamine, dibenzylamine, and diethanola ine ; tertiary amines, such as trimethylamine, triethylamine , and triethanolamine ; cyclic amines, such as morpholine, piperazine, and pyridine; polyamines , such as ethylenediamine and hexamethylenediamine ; ammonium hydroxides, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylbenzylammonium hydroxide, and trimethylphenylbenzylammonium hydroxide; sulfonium hydroxides, such as trimethylsulfonium hydroxide, diethylmethylsulfonium hydroxide, and dimethylbenzylsulfonium hydroxide; cholines ; and silicate-containing buffers. The type, composition, and concentration of the developer, as well as time, temperature,manner of operation (e.g., dipping, agitation, showering, spraying, and paddling) , and apparatus used in the development process , may properly be selected based on the properties of the photosensitive insulative paste composition. The baking process may be carried out at any temperature high enough to burn out any organic materials present in the photosensitive insulative paste composition. The process may be carried out, for example, at 400 to 600°C for 10 to 90 minutes. While the photosensitive insulative paste composition of the present invention can be widely used in the production of thick multi-layered circuits , as well as in the production of plasma displays, plasma address liquid crystal displays, and various other displays, it is particularly suitable for the production of barrier ribs or the like used in high- precision PDPs and, specifically, for the production of dielectrics used in PDPs.

Examples The present invention will now be described with reference to several examples, which are not intended to limit the scope of the invention in any way.

Example 1

(Preparation of photosensitive insulative paste composition) The following organic components were mixed together on a stirrer for 3 hours to form a solution (solid component =

50%) : 15 parts by weight of hydroxypropyl cellulose as the water-soluble cellulose derivative, 33 parts by weight of a styrene/hydroxyethylmethacrylate copolymer

(styrene/hydroxyethylmethacrylate = 55/45 (% by weight) , MW = 8500) as the hydroxyl-containing acrylic resin, 39 parts by weight of 2-hydroxy-3-phenoxypropylacrylate (Product name: M- 600A, Kyoeisha Chemical Co., Ltd.) as the photopolymerizable monomer, 1.0 part by weight of 2 , 2-dimethoxy-2- phenylacetophenone (Product name: IR-651, Ciba Geigy Ltd.) as the photopolymerization initiator, 12 parts by weight of dicyclohexyl phthalate as the plasticizer, and 100 parts by weight of 3-methoxy-3-methylbutanol as the solvent. 35 parts by weight of this solution (solid component = 50%) were mixed/kneaded with 82.5 parts by weight of glass frits as the inorganic powder to form a photosensitive insulative paste composition.

(Preparation of photosensitive film) Using a lip coater, the photosensitive insulative paste composition thus obtained was applied to a polyethylene terephthalate supporting film. The coating was dried at

100°C for 6 minutes to completely remove the solvent. This left a 27μm thick film of the photosensitive insulative paste formed on the supporting film. The coating layer of the

photosensitive insulative paste was then covered with a 25μm thick polyethylene film. This completed a photosensitive film.

(Evaluation of photosensitive film) Using a hot roll laminator set at 105°C, a glass substrate, preheated to 80°C, was laminated with the resulting photosensitive film while the polyethylene film was peeled off therefrom. The air pressure and the laminate speed used were 3kg/cm² and l.Om/min, respectively. Subsequently, the polyethylene terephthalate supporting film was peeled off. Using an ultra-high pressure mercury lamp as the light source, an ultraviolet ray was then irradiated onto the photosensitive coating at a dose of 500mJ/cm² through a mask having a square test pattern. To develop the pattern,

30°C water was sprayed onto the exposed coating at a pressure of 3kg/cm² over a time period five times as long as it took the film to reach the break point. The term "break point" as used herein refers to the time that it takes until the material in the unexposed area has been completely removed. The minimum line width that had remained was determined as a measure of the adhesion of the formed pattern and was

determined to be 40μm. The formed pattern was observed with SEM and was found to be a trapezoidal pattern. The pattern formed in this manner was baked to evaluate its shape stability. The baking process was carried out by first

heating the film at a rate of 1.0°C/min and then maintaining at 580°C for 30 minutes. The baked pattern was proved to be satisfactory.

Comparative Example 1 (Preparation of photosensitive insulative paste composition) The following organic components were mixed together on a stirrer for 3 hours to form a solution: 15 parts by weight of hydroxypropyl cellulose as the water-soluble cellulose derivative, 33 parts by weight of a styrene/hydroxyethylmethacrylate copolymer (styrene/hydroxyethylmethacrylate = 55/45 (% by weight) , MW = 25000) as the hydroxyl-containing acrylic resin, 39 parts by weight of 2-hydroxy-3-phenoxypropylacrylate (Product name: M- 600A, Kyoeisha Chemical Co., Ltd.) as the photopolymerizable monomer, 1.0 part by weight of 2 , 2-dimethoxy-2- phenylacetophenone (Product name: IR-651, Ciba Geigy Ltd.) as the photopolymerization initiator, 12 parts by weight of dicyclohexyl phthalate as the plasticizer, and 100 parts by weight of 3-methoxy-3-m thylbutanol as the solvent. 35 parts by weight of this solution were kneaded with 82.5 parts by weight of glass frits as the inorganic powder to form a photosensitive insulative paste composition.

(Preparation of photosensitive film) Using a lip coater, the photosensitive insulative paste composition was applied to a polyethylene terephthalate

supporting film. The coating was dried at 100°C for 6 minutes to completely remove the solvent. This left a 27μm thick film of the photosensitive insulative paste formed on the supporting film. The coating layer of the photosensitive

insulative paste was then covered with a 25μm thick polyethylene film. This completed a photosensitive film.

(Evaluation of photosensitive film)

Using a hot roll laminator set at 105°C, a glass substrate, preheated to 80°C, was laminated with the resulting film of the photosensitive insulative paste while the polyethylene film was peeled off therefrom. The air pressure and the laminate speed used were 3kg/cm² and l.Om/min, respectively. Subsequently, the polyethylene terephthalate supporting film was peeled off. Using an ultra-high pressure mercury lamp as the light source, an ultraviolet ray was then irradiated onto the photosensitive coating at a dose of 500mJ/cm² through a mask having a square

test pattern. To develop the pattern, 30°C water was sprayed onto the exposed coating at a pressure of 3kg/cm² over a time period five times ^' as long as it took the film to reach the break point. The minimum line width that had remained was determined as a measure of the adhesion of the formed pattern and was

determined to be 0μm. However, the development of the pattern was incomplete and residues were seen.

INDUSTRIAL APPLICABILITY As set forth, the photosensitive insulative paste composition of the present invention, containing an organic component that imparts superior developer resistance to the composition, is suitable for forming thick but still highly sensitive layer and, thus, high-precision patterns. The photosensitive insulative paste composition of the present invention is suitable for the production of photosensitive films.

Claims

1. A photosensitive insulative paste composition containing an organic component and an inorganic powder, wherein the organic' component comprises (A) a water-soluble cellulose derivative, (B) a hydroxyl-containing acrylic resin having a molecular weight of 20000 or less, (C) a photopolymerizable monomer, and (D) a photopolymerization initiator .

2. The photosensitive insulative paste composition according to claim 1, containing 10 to 50 parts by weight of the component (A) and 90 to 50 parts by weight of the component (B) with respect to 100 parts by weight of the total amount of the component (A) and the component (B) in the organic component.

3. The photosensitive insulative paste composition according to claim 1, wherein the inorganic powder is a glass powder.

4. The photosensitive insulative paste composition according to claim 1, containing 10 to 50 parts by weight of the component (A) and 90 to 50 parts by weight of the component (C) with respect to 100 parts by weight of the total amount of the component (A) and the component (C) in the organic component.

5. The photosensitive insulative paste composition according to claim 1, containing 5 to 35 parts by weight of the organic component and 95 to 65 parts by weight of the inorganic powder with respect to 100 parts by weight of the total amount of the organic component and the inorganic powder .

6. A photosensitive film comprising a supporting film and a layer of the photosensitive insulative paste composition according to any one of clams 1 to 5 formed on the supporting film.