JP2005279374A - Method and apparatus for manufacturing paste containing inorganic powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacture of a paste containing an inorganic powder allowing continuous treatment with reduced amounts of foreign matter and giving a paste having excellent dispersibility in a short treating time. <P>SOLUTION: The method for manufacture of the paste containing the inorganic powder comprises kneading by the use of a kneader having two or more supply ports for raw materials at the upper part of the edge of the trough. The parts of kneader coming in contact with the paste raw materials supplied from the supply ports are composed of or coated with a ceramic material, and the paste raw materials are kneaded by the kneader. The kneader having a paddle and a screw and two or more supply ports for raw materials at the upper part of the edge of the trough, with its parts coming in contact with the paste raw materials from the supply ports being composed or or coated with a ceramic material, is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a paste containing inorganic powder and a manufacturing apparatus therefor.

  A plasma display panel (hereinafter abbreviated as PDP) has attracted attention as a display that can be used for a thin and large television. A plurality of paired sustain electrodes are formed of a material such as silver, chromium, aluminum, and nickel on a glass substrate on the front plate side serving as a display surface of the PDP. Further, a dielectric layer mainly composed of glass is formed by covering the sustain electrode with a thickness of 20 to 50 μm, and the MgO layer is formed by covering the dielectric layer. On the other hand, a plurality of address electrodes are formed in stripes on the glass substrate on the back plate side of the PDP, and a dielectric layer mainly composed of glass is formed by covering the address electrodes. A partition for partitioning the discharge cells is formed on the dielectric layer, and a phosphor layer is formed in the discharge space formed by the partition and the dielectric layer. In a PDP capable of full color display, the phosphor layer is made of a material that emits light of red, green, and blue (RGB). The front plate and the back plate are sealed so that the sustain electrode of the glass substrate on the front plate side and the address electrode on the back plate side are orthogonal to each other, and helium, neon, xenon, etc. are formed in the gap between the substrates. The rare gas to be sealed is filled to form a PDP. Thus, since the pixel cell is formed around the intersection of the scan electrode and the address electrode, the PDP has a plurality of pixel cells, and an image can be displayed.

  For such electrodes, dielectrics, barrier ribs and phosphor layers, pastes in which inorganic powders such as metal powders, glass powders and phosphor powders are dispersed in a binder resin are usually used. As a method for dispersing these inorganic powders in a binder resin, conventionally, a roll mill such as a three-roller has been frequently used.

  However, since the three-roller is an open system and batch type, the three rollers have various problems in terms of quality, manufacturing cost, working environment and the like when used for manufacturing a PDP paste. For example, the working environment deteriorates due to evaporation of the solvent from the paste, the number of processes increases such as adjusting the viscosity again because the viscosity changes, the entry of foreign matter from the working environment, around three rollers for continuous processing If the roll diameter is increased and the roll length is increased in order to increase the throughput, the equipment becomes heavier or the dispersion is poor due to uneven gaps between the rolls. is there.

  As an alternative to these open and batch type three rollers, there is a sand mill (for example, see Patent Document 1). The sand mill can have a closed structure and can be continuously processed. However, when used for dispersing the PDP paste, it is difficult to control the pulverization conditions, which makes it difficult to apply to the production of the PDP paste. Specifically, for example, there is a problem that the luminance decreases due to the change in the particle size of the phosphor powder or the particle size distribution of the metal powder or the glass powder changes, resulting in a change in the photosensitive characteristics of the photosensitive paste. In addition, since the PDP paste contains a large amount of inorganic powder, the paste viscosity is tens of thousands of mPa · s, and the medium concentrates on the screen or gap separator disposed at the exit portion of the sand mill, making it impossible to operate. There was also a problem.

  Moreover, there is a vibration type disperser as a disperser that can have a sealed structure, can be continuously processed, and hardly damages the physical properties of the target material to be dispersed (for example, see Patent Document 2). This vibratory disperser is to disperse by the repeated phenomenon of vortex generation / disintegration caused by vibrating stirring blades. However, when it contains a large amount of highly abrasive inorganic powder, the metal caused by abrasion of the stirring blades and inner walls Since foreign matter is mixed in, it is difficult to apply in the manufacture of PDP paste.

Moreover, in these dispersers, in order to maintain stable quality, it is necessary to prepare various paste raw materials in advance so as to have a predetermined composition, and to disperse the paste obtained by performing preliminary dispersion with a mixer such as a planetary mixer. was there.
Japanese Utility Model Publication No. 7-7740 (pages 1 to 4) JP-A-2-293035 (pages 1 to 5)

  Therefore, an object of the present invention is to provide a method and an apparatus for producing an inorganic powder-containing paste that can be continuously processed, has a small amount of foreign matter, and has excellent dispersibility in a short processing time.

  The present invention is intended to solve the above problems, and the method for producing an inorganic powder-containing paste of the present invention includes an inorganic powder containing a kneading process using a kneader having a plurality of raw material supply ports in a trough. An inorganic powder-containing paste comprising a kneader using a kneader in which a contact portion with a raw material supplied from the raw material supply port is made or coated with a ceramic material. It is a manufacturing method.

Moreover, the manufacturing method of said inorganic powder containing paste of this invention has the following preferable aspect.
(a) The contact portion with the raw material of the kneader is the raw material supply port, the trough inner wall, the paddle and the screw.
(b) The clearance between the trough inner wall and paddle of the kneader and the trough inner wall and screw is in the range of 0.3 to 3.0 mm.
(c) Supply the raw material from the raw material supply port using a quantitative feeder and a quantitative pump.
(d) The temperature of the raw material of the inorganic powder-containing paste being kneaded is in the range of 15 ° C to 90 ° C.
(e) The content of the inorganic powder in the inorganic powder-containing paste is in the range of 35 to 95% by weight.
(f) The inorganic powder is at least one selected from glass, phosphor and metal.
(g) The inorganic powder-containing paste contains a compound having an unsaturated double bond.

  The apparatus for producing an inorganic powder-containing paste of the present invention is a kneader provided with a paddle and a screw in a trough. The kneader has a plurality of raw material supply ports at the upper end of the trough, and is supplied from the raw material supply port. An apparatus for producing an inorganic powder-containing paste, wherein the contact portion with the raw material is made or coated with a ceramic material.

  According to the present invention, the paste containing inorganic powder is kneaded using a kneader having a contact portion with the paste made or coated with a ceramic material and having a plurality of raw material supply ports at the top of the trough end. Thus, it is possible to obtain an inorganic powder-containing paste that can be continuously processed, has a small amount of foreign matter, and has excellent dispersibility in a short processing time.

  An example of a kneader (dispersing machine) used for dispersing and kneading the inorganic powder-containing paste of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view for illustrating a kneader used in the present invention, and FIG. 2 is a schematic partial cross-sectional view thereof.

  1 and 2, the apparatus (kneader) has a plurality of raw material supply ports 2 at the upper end of a cylindrical trough 1, and the raw material of the inorganic powder-containing paste supplied from the raw material supply port 2 The material supply port 2, the trough inner wall 3, the paddle 4, the screw 5, and the like, which are the contact portions, are made of ceramic material or coated with ceramic material. Moreover, about the fixed quantity feeder and the fixed quantity pump, the part which the inorganic powder raw material and the inorganic powder containing paste pass and contacts is ceramic-processed.

  The shape of the trough 1 is generally a horizontal sealed type, and the raw material is supplied from the raw material supply port 2 at the upper end of one end, and the paste is discharged from the discharge port 5 provided at the lower portion or the side of the other end. Examples of the type of trough 1 include an upper open type, an upper and lower open type, and an integrated type. Moreover, it is common that the jacket 7 is attached to the trough 1 so that heating and cooling can be performed. Examples of the paddle 4 include a flat paddle for kneading, a helical paddle that takes feed into kneading, and a reverse helical paddle that performs reverse feeding. Examples of the type of the screw 5 include a feed screw that performs forward feed and a reverse screw that performs reverse feed. The paddle 4 and the screw 5 can be freely recombined one by one in accordance with the purpose and purpose, and thereby the kneading state can be adjusted by adjusting the residence time and internal pressure. In the two-axis kneader, the paddle 4 and the screw 5 are incorporated in two shafts parallel to the horizontal direction in a state where the phase is 90 ° C., and rotate at the same speed.

  In the present invention, the contact portion with the raw material is made of a ceramic material, so that even if it is polished and mixed as a foreign material, the quality effect on the paste is small compared to the case where a metal-based foreign material is mixed. The body has a small effect on the quality characteristics of luminance reduction.

  Specific examples of the ceramic material suitably used in the present invention include zirconia, alumina, silicon nitride, silicon carbide, aluminum nitride, sialon, and zirconia / alumina mixture. In particular, zirconia and sialon are preferably used from the viewpoint of wear resistance, low thermal conductivity, and thermal expansibility. As a specific example of the coating method of ceramic materials, thermal spraying method is applied by applying heat to the coating material, melting it, spraying it on the surface of the material as liquid fine particles of tens to hundreds of μm, and colliding and flattening them. Is preferably used. Examples of the heat source for thermal spraying include plasma, laser, arc and gas.

  Further, specific examples of the material of the member coated with the ceramic material include stainless steel materials and metal alloys such as Ni—Cr and Ni—Al.

  The kneader in FIG. 1 has a plurality of raw material supply ports 2 at the upper end of the trough 1, so that powder such as inorganic powder or liquid paste raw material is charged into the hopper 10 and supplied from separate raw material supply ports 2. Therefore, continuous processing is possible. As a continuous processing method, a method of supplying an inorganic powder or liquid paste raw material to the raw material supply port 2 using a quantitative feeder 8 and a quantitative pump 9 is preferable.

  Specific examples of the quantitative feeder 8 include a screw feeder, a twin screw feeder, a coil feeder, a belt feeder, an electromagnetic feeder, a vibratory feeder, and a rotary feeder. In addition, regarding the quantitative feeder 8 for supplying the inorganic powder, it is preferable that the contact portion with the paste raw material such as the cut-out portion is made or coated with a ceramic material such as zirconia or sialon because the wear resistance can be improved. It is.

  Specific examples of the metering pump 9 include a single stage centrifugal pump, a multistage centrifugal pump, a single stage turbine pump, a centrifugal pump such as a borehole pump, an axial flow pump, a propeller pump such as a diagonal flow pump, a single stage vortex pump, Viscous pumps such as multistage vortex pumps, horizontal piston pumps, vertical piston pumps, horizontal blanker pumps, vertical blanker pumps, diaphragm pumps, tube pumps, reciprocating pumps such as wing pumps, external gear pumps, internal gear pumps, eccentricity Examples thereof include rotary pumps such as screw pumps, vane pumps, and roller pumps. In order to supply a paste material having a high viscosity, a diaphragm pump or an eccentric screw pump is preferably used. Also for the metering pump 9 and the inner wall of the hopper 10, it is a preferable aspect that the wetted part is made or coated with a ceramic material because the wear resistance can be improved. By using the quantitative feeder 8 and the quantitative pump 9, an inorganic powder-containing paste having a stable quality such as dispersibility can be obtained.

  In the present invention, the mutual clearances of the trough inner wall 3, the paddle 4 and the screw 5 are preferably in the range of 0.3 to 3.0 mm, respectively. When the clearance is within this range, an inorganic powder-containing paste having a small amount of foreign matter and excellent dispersibility can be obtained. If this clearance is less than 0.3 mm, the production portion of the ceramic material or the coating portion may be cracked due to interference between the trough 1 due to shaft runout and the paddle 4 or screw 5, or interference between the paddle 4 or screw 5. Chipping may occur and may cause contamination. On the other hand, when the clearance is larger than 3.0 mm, the problem of cracking or chipping of the ceramic material or the coating portion is solved, but the dispersibility is lowered because the shearing force is reduced and the paste that is short-passed is increased. There is a tendency to end up.

  The temperature of the raw material of the inorganic powder-containing paste kneaded in the kneader is preferably in the range of 15 ° C to 90 ° C. If the temperature is lower than 15 ° C, condensation may occur. If the temperature exceeds 90 ° C, the composition ratio may change due to volatilization or the reaction may proceed depending on the paste composition. It is. Examples of the method for adjusting the temperature of the paste raw material include a method in which a jacket is attached to a trough and a heating medium / refrigerant is passed therethrough, and a method for changing manufacturing conditions such as the number of rotations of paddles and screws.

  The inorganic powder-containing paste obtained in the present invention is mainly composed of inorganic powder and a binder resin. The content of the inorganic powder in the inorganic powder-containing paste is preferably 35 to 95% by weight, and more preferably 40 to 90% by weight. This is because, when the range is selected, the shrinkage rate during firing is small, and the shape change due to firing is small. Examples of the inorganic powder blended in the paste include glass powder, phosphor powder, and metal powder.

The glass powder preferably has a thermal expansion coefficient of 50 × 10 ^{−7 to} 100 × 10 ⁻⁷ at 50 to 400 ° C. Further, by blending silicon oxide in the glass preferably in the range of 3 to 60% by weight and boron oxide in the range of preferably 5 to 50% by weight, electrical insulation, strength, thermal expansion coefficient, denseness of the insulating layer, etc. The electrical, mechanical and thermal characteristics required for the barrier ribs can be improved. The glass powder used in the present invention is preferably mainly composed of a low-melting glass powder. The glass transition temperature of the low melting glass powder is preferably 430 to 500 ° C, and the glass softening point is preferably 470 to 620 ° C. When the glass transition temperature and the glass softening point are in this range, the distortion of the substrate is small during firing, and a dense partition layer is obtained. The particle diameter of the glass powder is selected in consideration of the line width and height of the partition wall to be produced. It is preferable that it is 1.5-4 cm < ² > / g.

Examples of the phosphor powder used in the present invention include Y ₂ O ₃ : Eu, YVO ₄ : Eu, (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ S: Eu, and γ-Zn _{3 in} red. (PO ₄ ) ₂ : Mn, (ZnCd) S: Ag + In ₂ O _{3 and the} like. In green, Zn ₂ GeO ₂ : M, BaAl ₁₂ O ₁₉ : Mn, Zn ₂ SiO ₄ : Mn, LaPO ₄ : Tb, ZnS: Cu, Al, ZnS: Au, Cu, Al, (ZnCd) S: Cu, Al, Zn ₂ SiO ₄ : Mn, As, Y ₃ Al ₅ O ₁₂ : Ce, CeMgAl ₁₁ O ₁₉ : Tb, Gd ₂ O ₂ S: Tb, Y ₃ Al ₅ O ₁₂ : Tb, ZnO: Zn, etc. Can be mentioned. In blue, Sr ₅ (PO ₄ ) ₃ Cl: Eu, BaMgAl ₁₄ O ₂₃ : Eu, BaMgAl ₁₆ O ₂₇ : Eu, BaMg ₂ Al ₁₄ O ₂₄ : Eu, ZnS: Ag + red pigment, and Y ₂ SiO ₃ : Ce Etc.

The phosphor powder is at least one element selected from the group consisting of thulium (Tm), terbium (Tb) and europium (Eu), and is selected from yttrium (Y), gadolinium (Gd) and lutetium (Lu). It is also possible to use a tantalate rare earth phosphor substituted with at least one rare earth element constituting the matrix. Preferably, the rare earth phosphor of tantalate is a europium-activated yttrium tantalate fluorescence represented by the composition formula Y _1-X Eu _x TaO ₄ (wherein X is approximately 0.005 to 0.1). Is the body. Europium activated yttrium tantalate is preferably used for the red phosphor, and the rare earth phosphor of tantalate is used for the green phosphor, where the composition formula is Y _1-X Tb _x TaO ₄ (wherein X is about 0. 0). Terbium activated yttrium tantalate represented by the formula (1) is preferably used. In addition, the blue phosphor includes a thallium activated tantalum acid in which the rare earth tantalate phosphor is represented by Y _1-X Tm _X TaO ₄ (wherein X is approximately 0.001 to 0.2). Yttrium is preferably used.

  The phosphor powder used in the inorganic powder-containing paste obtained in the present invention has an area average diameter (Ds) of 1.0 to 2.5 μm and a volume-based distribution center diameter (Dv) of 1.8 to 4.5 μm. Ds / Dv is preferably 1.2 to 2.5, more preferably Ds is 1.2 to 2.3 μm, Dv is 2.0 to 4.2 μm, and Ds / Dv is 1.3 to Within the range of 2.3. When Ds, Dv, and Ds / Dv are in such ranges, the filterability of the paste can be improved.

  As the metal powder, a metal containing at least one selected from the group of Ag, Au, Pd, Ni, Cu, Al and Pt can be preferably used. These metals can be used independently, in an alloy or mixed powder state. The particle diameter of the metal powder is preferably such that the center diameter of the volume-based distribution is in the range of 0.7 to 6 μm, more preferably in the range of 1.3 to 4 μm. When the particle diameter is in this range, a fine fine pattern can be formed.

  The binder resin used in the present invention is preferably oxidized or / and decomposed or / and vaporized at the time of firing so that the carbide does not remain in the inorganic substance. Examples of such a binder resin include ethyl cellulose, methyl cellulose, nitrocellulose, and cellulose acetate. , Cellulose-based resins such as cellulose propionate and cellulose butyrate, or methyl (meth) acrylate, ethyl (meth) acrylate, normal butyl (meth) acrylate, isobutyl (meth) acrylate, isopropyl (meth) acrylate, 2- Acrylic resin, poly-α-methylsulfone, polyvinyl alcohol, and polybutene made of a polymer or copolymer such as ethylmethyl (meth) acrylate and 2-hydroxylethyl (meth) acrylate It is preferably used. The content of the binder resin in the inorganic powder-containing paste of the present invention is preferably in the range of 5 to 65% by weight, more preferably in the range of 10 to 60% by weight.

  Examples of other components of the inorganic powder-containing paste obtained in the present invention include additive components such as organic solvents, plasticizers, antioxidants, antifoaming agents, dispersants and leveling agents, and refractory fillers. . In particular, when the inorganic powder-containing paste obtained in the present invention is used as a photosensitive paste, a photosensitive component such as a photosensitive polymer, a photosensitive oligomer, a photosensitive monomer, a photopolymerization initiator, a sensitizer, Additive components such as UV absorbers and polymerization inhibitors can be added.

  An organic solvent is used to adjust the viscosity when the paste containing the inorganic powder is applied to the substrate in accordance with the application method. Examples of the organic solvent used at this time include diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, 2,2,4-trimethyl-1, 3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 2-ethyl-1,3-hexanediol, terpineol, benzyl alcohol, 1-butoxy-2-propane 1,2-diacetoxypropane, 1-methoxy-2-propanol, 2-acetoxy-1-ethoxypropane, (1,2-methoxypropoxy) -2-propanol, (1,2-ethoxypropoxy)- -Propanol, 2-hydroxy-4-methyl-2-pentanone, 3-methoxy-3-methylbutyl acetate, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethanol, 2-isopropoxyethanol, 2 -Butoxyethanol, 2- (isopentyloxy) ethanol, 2- (hexyloxy) ethanol, 2-phenoxyethanol, 2- (benzyloxy) ethanol, benzyl alcohol, furfuryl alcohol, tetrafurfuryl alcohol, 2,2'- Dihydroxydiethyl ether, 2- (2-methoxyethoxy) ethanol, 2- [2- (2-methoxyethoxy) ethoxy] ethanol, 2-methyl-1-butanenor, 3-methyl-2-butanol, 2-methyl-1 -Pentanol, -Methyl-2-pentanol, 2-ethyl-1-butanol, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-phenoxyethyl acetate, 1,2-dimethoxyethane, 1,2 -Diethoxyethane, 1,2-dibutoxyethane, cyclohexanenone, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate Benzyl acetate, hexane, cyclohexane, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone and diisobutyl ketone.

  The organic solvent is preferably a good solvent for the binder resin used. Further, the solvent is selected by mainly considering the volatility of the solvent and the solubility of the binder resin to be used. This is because if the solubility of the solvent in the binder resin is low, the viscosity of the coating liquid increases even if the solid content ratio is the same, and the coating properties tend to deteriorate.

  If the content of the organic solvent is too small, the viscosity of the phosphor paste becomes so high that it is difficult to remove bubbles in the partition wall forming material, and the smoothness of the coated surface tends to be poor due to poor leveling. On the other hand, when the content of the organic solvent is too high, the sedimentation of the dispersed particles becomes faster, it becomes difficult to stabilize the composition of the phosphor paste, and the drying requires a lot of energy and time. Therefore, the preferable content of the organic solvent is preferably 35 to 65 wt%, more preferably 40 to 60 wt% in the inorganic powder-containing paste.

  The refractory filler is preferably added to the inorganic powder-containing paste in order to stabilize the shape during firing. As the refractory filler, those that do not soften at a firing temperature of about 500 to 650 ° C. can be widely used. As such a refractory filler, high melting point glass, alumina, magnesia, calcia, cordierite, silica, mullite. And ceramic powders such as zircon and zirconia.

  In order to reduce external light reflection of the PDP and increase the practical contrast, when the partition walls are dark, Co-Cr-Fe, Co-Mn-Fe, Co-Fe-Mn are used as refractory black pigments. -Al, Co-Ni-Cr-Fe, Co-Ni-Mn-Cr-Fe, Co-Ni-Al-Cr-Fe, and Co-Mn-AL-Cr-Fe-Si pigments may be used. . On the other hand, when whitening the partition for the purpose of effectively guiding the light emission of the phosphor to the front surface of the panel, titania or the like may be used as a fire-resistant white pigment.

  As the photosensitive monomer, a compound having an active carbon-carbon unsaturated double bond is often used. Monofunctional and polyfunctional compounds having a vinyl group, an allyl group, an acrylate group, a methacrylate group, and an acrylamide group can be applied as the functional group. Specific examples of the photosensitive monomer include 2- (2-ethoxyethoxy) ethyl acrylate, 1,3-butanediol diacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, cyclohexyl methacrylate, and ethylene glycol dimethacrylate. , Trimethylolpropane trimethacrylate and glycidyl methacrylate.

  When the inorganic powder-containing paste obtained in the present invention is used as a photosensitive paste, it is preferable to use a photosensitive polymer and / or a photosensitive oligomer as a binder resin. The oligomer or polymer is usually obtained by polymerization or copolymerization of components selected from compounds having a carbon-carbon double bond.

  By copolymerizing an unsaturated acid such as an unsaturated carboxylic acid, the developability in an alkaline aqueous solution after exposure can be improved. Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, and acid anhydrides thereof.

  The acid value of the polymer or oligomer having an acidic group such as a carboxyl group in the side chain thus obtained is preferably in the range of 50 to 180, more preferably in the range of 70 to 140.

  When the acid value of the above polymer or oligomer is lower than 50, there may be a problem that the polymer or oligomer does not dissolve in the developing solution or the development time becomes long, and when the oxidation is higher than 180, exposure occurs during development. There may be a problem that the portion is easily peeled off and the development margin becomes small.

  In addition, the photopolymerization initiator is preferably added in the range of 0.005 to 5% by weight with respect to the photosensitive paste in terms of photosensitive characteristics.

  Regarding the kneading process, the kneading state can be adjusted by adjusting the residence time, internal pressure and the like according to the combination pattern of the paddle and screw, the paddle rotation speed, the paste discharge amount, the heating / cooling temperature, and the like.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these. In the examples, the concentration (%) is% by weight unless otherwise specified.

[Paste composition]
(1) Partition wall paste 52% glass powder having an average particle diameter of 2 μm obtained by pulverizing glass mainly composed of lead oxide, boron oxide, zinc oxide, silicon oxide and barium oxide, methyl methacrylate / methacrylic acid copolymer (weight) % Composition ratio 60/40, weight average molecular weight 32,000) 12%, dipentaerythritol hexaacrylate 12%, benzophenone 1.94%, 1,6-hexanediol-bis [(3,5-di-t-butyl -4-hydroxyphenyl) propionate], a photosensitive paste comprising 0.05%, organic dye (Basic Blue 7) 0.01%, and organic solvent (propylene glycol monomethyl ether acetate) 22%.

(2) Red phosphor paste (Y, Gd, Eu) BO _{3 having} an average particle size of 3 μm phosphor powder 35%, ethyl cellulose 7%, and organic solvent (terpineol) 58%.

(3) Green phosphor paste (Zn, Mn) ₂ SiO ₂ phosphor powder having an average particle diameter of 2.5 μm 33.5%, ethyl cellulose 6.5%, and organic solvent (terpineol) 60%.

(4) Blue phosphor paste (Ba, Eu) 33.5% phosphor powder having an average particle diameter of 2 μm, MgAl ₁₀ O ₁₇ , 6.5% ethyl cellulose, and 60% organic solvent (terpineol).

(5) 80% lead borosilicate glass having a dielectric paste softening point of 410 ° C. and an average particle size of 5 μm, 2% ethyl cellulose, and 18% organic solvent (terpineol).

(6) Electrode paste 3% glass powder having an average particle diameter of 0.8 μm obtained by grinding glass composed of bismuth oxide, silicon oxide, boron oxide, zirconium oxide, zinc oxide and aluminum oxide, methyl methacrylate / methacrylic acid copolymer (weight) % Composition ratio 60/40, weight average molecular weight 32,000) 6%, dipentaerythritol hexaacrylate 3%, benzophenone 1%, Ag powder 74% average particle size 1.2 μm, and organic solvent (propylene glycol monomethyl ether acetate) ) A photosensitive paste consisting of 13%.

[Paste evaluation method]
(1) Viscosity use device: Field type viscometer (Brookfield, model DV-III)
Measurement conditions: rotation speed 3 rpm, measurement temperature 25 ° C.

(2) Dispersibility use device: Grind gauge (Eriksen, 0-50 μm)
Evaluation method: The distribution density of the crush was observed, and the scale where the dense crush appeared was read. However, when a dense crushing boundary appears between the scales or when the values of the two grooves are different, read the scale with the larger number and paste the median of the three measurements. The degree of dispersion was. As an evaluation standard, 10 μm or less was determined as “good”.

(3) After 20 kg of the paste after kneading and dispersing the amount of foreign matter is filtered through a 293 mmφ disk filter (filtration pressure: 0.2 MPa, filter: 500 mesh), the filter is placed in a clean container, immersed in clean acetone, and an ultrasonic cleaner. For 30 minutes. After washing, the washing liquid was further filtered through a 25 mmφ disk filter (filtration pressure: 0.05 MPa, filter: nylon net [pore diameter 11 μm]), and the amount of foreign matter remaining on the filter was measured with a precision balance. As evaluation criteria, 40 mg or less was defined as “good”.

(Examples 1-5, Comparative Example 1)
As the kneaders of Examples 1 to 5, the shape and type of trough were those of a horizontal closed type and an open top type. As a paddle combination, a feed screw was combined with the raw material supply port, a reverse screw was combined with the discharge port, and a flat paddle was combined with the other portions. Zirconia reinforced alumina was sprayed on the inner wall of the trough and the wetted parts of the paddle, screw, metering feeder and metering pump, and SUS316 was used as the base material. In the kneader of Comparative Example 1, the combination of the paddle and screw was the same as in Examples 1 to 5, and the material of the wetted parts of the trough inner wall, paddle, screw, metering feeder, and metering pump was SUS316.

  A biaxial screw feeder (manufactured by Kurimoto Steel Works) is used to supply the inorganic powder to the supply port, and a double diaphragm pump (manufactured by Irie Seisakusho) is used to supply other raw materials such as polymer solutions. The paste shown in Table 1 and Table 2 was used for the paste. The conditions of the trough inner wall and paddle, the trough inner wall and screw clearance, and the number of passes were as shown in Tables 1 and 2. The operating conditions of the kneader were such that the paddle rotation speed was 150 rpm, and the amount of discharge of the paste supplied and kneaded from the raw material exited from the discharge port was 120 kg / hr. Further, cooling water at 15 ° C. was circulated in the jacket to be cooled. Subsequently, the paste containing inorganic powder obtained after completion of the kneading dispersion was filtered. Filtration was performed with a 293 mmφ disk filter (filtration pressure: 0.2 MPa, filter: 500 mesh). The treatment amount of each paste was 20 kg, and the time required for the dispersion treatment of 20 kg, the degree of dispersion after the dispersion treatment, the viscosity, and the amount of foreign matter on the disk filter were measured. The results are shown in Tables 1 and 2.

(Comparative Examples 2 to 4)
A predetermined amount of each paste shown in Table 2 was weighed and then predispersed with a planetary mixer (Inoue Seisakusho). The conditions at this time were 60 minutes at 30 rpm. After completion of the preliminary dispersion, the container was divided into 10 2-liter polyethylene (PE) containers, and the dispersion treatment was performed with three rollers (manufactured by Inoue Seisakusho) with ceramic sprayed on the roll surface by hand injection. The processing conditions were such that the rotational speed of the roller was 40 rpm. In Comparative Example 2, the number of passes of the three rollers was 1; in Comparative Example 3, the number of passes was 2, and in Comparative Example 4, the number of passes was 3. Subsequently, the dispersion-finished paste was filtered. Filtration was performed with a 293 mmφ disk filter (filtration pressure: 0.2 MPa, filter: 500 mesh). The amount of each paste treated was 20 kg, and the time required for the 20 kg dispersion treatment, the degree of dispersion after the dispersion treatment, the viscosity, and the amount of foreign matter on the disk filter were measured. The results are shown in Table 2.

  The pastes obtained in Examples 1 to 3 had a small amount of foreign matter and a paste with good dispersibility was obtained in a short time. In Example 4, the amount of foreign matter was small although the dispersibility was slightly inferior. In Example 5, the dispersibility was good, and the amount of foreign matter was slightly increased but was in an allowable range.

  In Comparative Example 1, the dispersibility was good, but the amount of foreign matter increased. In Comparative Examples 2 to 4, a large amount of foreign matter was observed in each paste. Dispersibility improved as the number of passes increased, but the amount of foreign matter and paste viscosity increased. In order to improve the dispersibility, the number of passes required 3 times, and a long processing time was required.

  An inorganic powder-containing paste having excellent dispersibility, which is suitably used for manufacturing a plasma display panel, can be manufactured in a short processing time by a continuous process with a small amount of foreign matter. The plasma display panel is suitable for a display of a thin and large television and is useful.

FIG. 1 is a schematic side view for illustrating the kneader (dispersing machine) used in the present invention. FIG. 2 is a partial cross-sectional schematic view of FIG.

Explanation of symbols

1-Trough 2-Raw material supply port 3-Trough inner wall 4-Paddle 5-Screw 6-Discharge port 7-Jacket 8-Metering feeder 9-Metering pump 10-Hopper

Claims (8)

  A method for producing an inorganic powder-containing paste for kneading using a kneader having a plurality of raw material supply ports on a trough, wherein the contact portion with the raw material supplied from the raw material supply port is made of a ceramic material or A method for producing an inorganic powder-containing paste, which comprises kneading the raw material using a coated kneader.   The method for producing an inorganic powder-containing paste according to claim 1, wherein the contact portion with the raw material of the kneader is a raw material supply port, a trough inner wall, a paddle and a screw.   3. The method for producing an inorganic powder-containing paste according to claim 2, wherein the clearance between the trough inner wall and paddle of the kneader and the clearance between the trough inner wall and the screw are in the range of 0.3 to 3.0 mm.   The method for producing an inorganic powder-containing paste according to any one of claims 1 to 3, wherein the raw material is supplied from a raw material supply port using a quantitative feeder and a quantitative pump.   The method for producing an inorganic powder-containing paste according to any one of claims 1 to 4, wherein the temperature of the raw material of the inorganic powder-containing paste being kneaded is in the range of 15 ° C to 90 ° C.   The method for producing an inorganic powder-containing paste according to any one of claims 1 to 5, wherein the content of the inorganic powder in the inorganic powder-containing paste is in the range of 35 to 95% by weight.   The method for producing an inorganic powder-containing paste according to any one of claims 1 to 6, wherein the inorganic powder is at least one selected from glass, phosphor and metal.   The method for producing an inorganic powder-containing paste according to any one of claims 1 to 7, wherein the inorganic powder-containing paste contains a compound having an unsaturated double bond.

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