JPH0725665A - Production of formed ceramic article - Google Patents

Abstract

PURPOSE:To easily produce a formed ceramic article having denseness, homogeneity, high strength and excellent dimensional stability and a wide range of thickness from extremely thin to thick. CONSTITUTION:This formed ceramic article is obtained by baking after extrusion molding or roll forming of a mixed composition containing ceramic raw material powder, a water soluble binder, a dispersant consisting of a copolymer of a compound of general formula [AO is 2-4C oxyalkylene, whose 50-100mol.% is oxyethylene; R is 1-4C alkyl; (n) is 4-150] with maleic anhydride, its hydrolysate or a salt of the hydrolysate and water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for manufacturing a ceramic molded body, and more particularly to a method for easily manufacturing a ceramic molded body of various thicknesses from very thin to extremely thick.

[0002]

2. Description of the Related Art Ceramic moldings are used as insulating materials for multilayer wiring boards for electronic circuits, dielectric materials such as laminated capacitors, piezoelectric materials such as piezoelectric buzzers, and the like. As an example of the use that has recently received a great deal of attention, there is an alumina-based ceramic multilayer wiring board used for miniaturizing electronic parts or circuits. Ceramic molded bodies used in such fields are obtained by firing a so-called green sheet obtained by molding ceramics into rods, tapes or thin sheets. Typical molding methods are extrusion molding and cast molding. There is one type of doctor blade casting method.

The former extrusion molding method is a method in which a ceramic raw material powder is mixed with a water-soluble polymer as a binder and water as a medium, and the mixture is molded by a high-pressure or vacuum extruder. Here, polyvinyl alcohol, cellulose ether, or the like is used as the water-soluble polymer, and the ceramic raw material can be molded with a necessary minimum amount of water. With this method, it is possible to obtain a molded product that is dense and has good dimensional stability. Therefore, it is particularly used for a dielectric material such as a capacitor. However, in the case of a ceramic tape for a multilayer wiring board used in a computer or the like, it is about 0.
Since an extremely thin ceramic having a thickness of 1 to 0.3 mm is used, it is difficult to form a tape having a uniform thickness in the extrusion molding method because distortion occurs at the portions contacting both ends of the mold.

On the other hand, a doctor blade casting method is more widely used than the extrusion molding method. This method is a method in which a slurry obtained by mixing a ceramic raw material powder, a binder and a solvent is poured onto a carrier sheet, drawn to a certain thickness with a doctor blade, dried and peeled off from the carrier sheet to obtain a tape. With this method, a wide tape can be easily manufactured, but since the slurry viscosity is limited, it is not possible to form a thick and uniform tape due to the sedimentation of particles after casting, and the thickness is generally 1.2 mm
Was considered to be the limit. Further, in this method, a synthetic polymer having high film strength is required as a binder, and polyvinyl butyral is mainly used. In order to dissolve this polyvinyl butyral, it is necessary to use an organic solvent such as alcohol, ketone, chlorine-based solvent, aromatic solvent or the like, which causes problems in fire safety or environmental hygiene.

In order to solve the above problems, water-soluble binders such as polyvinyl alcohol and water-soluble polyurethane have been proposed, and water has come to be used as a medium. However, when these water-soluble binders are used, the ceramic raw material powder easily aggregates in the water-soluble solvent and the viscosity increases, so that the fluidity of the ceramics slurry is lowered, or the ceramics are poorly dispersed. However, there is a problem that it is difficult to obtain a desired molded product that is dense, has good dimensional stability, and has a smooth surface.

Further, various acrylic polymers have been proposed to solve the above-mentioned drawbacks of the water-soluble binder. For example, Japanese Patent Application Laid-Open No. 58-190867 discloses a technique in which a polyurethane resin and a water-soluble acrylic resin are combined, and Japanese Patent Application Laid-Open No. 59-121152 and Japanese Patent Application Laid-Open No. 60-1.
In 22769, a technique using a copolymer of acrylic acid esters and a carboxyl group-containing monomer,
Further, JP-A-60-155567 discloses a technique using a copolymer having an unsaturated carboxylic acid ester of alkoxy polyethylene glycol as an essential component.

[0007]

However, even if these various proposals are used, the above problems cannot be sufficiently solved. The present invention uses a water-soluble binder that does not cause any problems in terms of fire safety and environmental hygiene when manufacturing a ceramic molded body, has high dimensional accuracy, and extrudes a molded body of any thickness from very thin to thick. It is an object of the present invention to provide a method for producing by firing after forming or rolling roll forming.

[0008]

Means for Solving the Problems The gist of the present invention consists of 100 parts by weight of a ceramic raw material powder, 1 to 10 parts by weight of a water-soluble binder, and a compound represented by the general formula (1) as a dispersant and maleic anhydride. A mixed composition containing 0.1 to 10 parts by weight of a copolymer, a hydrolyzate thereof or a salt of the hydrolyzate and 5 to 30 parts by weight of water is extruded or rolled, and then fired. It is characterized by

(Wherein AO is an oxyalkylene group having 2 to 4 carbon atoms and 50 to 100 mol% thereof is an oxyethylene group,
R is an alkyl group having 1 to 4 carbon atoms, and n is 4 to 150. )

Examples of the ceramic raw material powder used in the method of the present invention include alumina, barium titanate, lead zirconate titanate, zirconia, titanium oxide, silicon nitride, silicon carbide and boron nitride.

As the water-soluble binder, a water-soluble resin which is usually used can be used, but it is particularly preferable to use water-soluble polyvinyl alcohol or water-soluble cellulose ether. Among them, water-soluble polyvinyl alcohol having a saponification degree of polyvinyl acetate of 70 mol% or more and a polymerization degree of 500 or less is preferable. Among the water-soluble cellulose ethers, methyl cellulose having a methoxy group substitution degree of 1.3 to 2.2 is preferable.

The oxyalkylene group having 2 to 4 carbon atoms and represented by AO in the compound represented by the general formula (1) used as a dispersant is an oxyethylene group, an oxypropylene group, an oxybutylene group or an oxytetramethylene group. Etc., but the oxyethylene group is 50 to 100 mol%
Occupy the above. When the oxyethylene group is less than 50 mol%, the water solubility becomes insufficient and the dispersion performance deteriorates. Examples of the alkyl group having 1 to 4 carbon atoms represented by R include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group.

The dispersant used in the present invention comprises the following copolymers (A) to (C). (A); a copolymer of the compound of general formula (1) and maleic anhydride, (B); (A)
The hydrolyzate of the maleic acid unit of (C); and the salt of all or part of the carboxyl groups of the maleic acid unit of (B). The molar ratio of the compound of the general formula (1) to maleic anhydride, maleic acid or maleic acid salt unit is 3: 7 to 7 :.
A copolymer in a ratio of 3 is preferable, and a copolymer in a ratio of 4: 6 to 6: 4 is particularly preferable. The copolymer of the compound of the general formula (1) and maleic anhydride can be easily obtained by copolymerizing the compound of the general formula (1) and maleic anhydride using a general polymerization initiator. .. Examples of the polymerization initiator include water-soluble initiators such as peroxide initiators, azo initiators, hydrogen peroxide, and persulfates. that time,
Other copolymerizable monomers such as styrene, α-olefin and vinyl acetate may be mixed and copolymerized.

Further, the hydrolyzate of the copolymer is obtained by copolymerizing the compound of the general formula (1) with maleic anhydride,
It can be obtained by hydrolyzing the maleic anhydride unit.
These include copolymers of the compound of general formula (1) and maleic acid. Further, the salt of the hydrolyzate of the copolymer is
It can be obtained by copolymerizing the compound of the general formula (1) and maleic anhydride and then hydrolyzing it with an aqueous solution containing a compound forming a salt with a maleic anhydride unit. This also includes a copolymer of the compound of the general formula (1) and a maleate salt.

Specific examples of these salts include lithium salts, sodium salts, potassium salts, magnesium salts, calcium salts, and other alkyl metal salts and alkyl earth metal salts, as well as ammonium salts and organic amine salts. To be Examples of the organic amine salt include methylamine salt, ethylamine salt, propylamine salt, butylamine salt, amylamine salt, hexylamine salt, octylamine salt, 2-ethylhexylamine salt, decylamine salt, dodecylamine salt, tridecylamine salt, and tetradecylamine salt. Decylamine salt, hexadecylamine salt, isohexadecylamine salt, octadecylamine salt, isooctadecylamine salt, octyldodecylamine salt, docosylamine salt, decyltetradecylamine salt, oleylamine salt, linoleamine salt,
Aliphatic or aromatic monoamine salts such as dimethylamine salt, trimethylamine salt, aniline salt, ethylenediamine salt, propylenediamine salt, tetramethylenediamine salt, diethylenetriamine salt, triethylenetetramine salt, tetraethylenepentamine salt, pentaethylenehexamine salt Polyamine salt, monoethanolamine salt, etc.
Alkanolamine salts such as diethanolamine salts, trietalamine salts, monoisopropanolamine salts, diisopropanolamine salts, triisopropanolamine salts, salts of these alkylene oxide adducts, salts of alkylene oxide adducts of primary or secondary amines, etc. , Amino acid salts such as lysine salt and arginine salt. Among these, sodium salt, potassium salt, ammonium salt and monoethanolamine salt are particularly preferable.

In the present invention, the mixing ratio of the water-soluble binder and the dispersant to the ceramic raw material powder is 1 to 1 with respect to 100 parts by weight of the ceramic raw material powder.
0 parts by weight, preferably 3 to 8 parts by weight, and a dispersant of 0.
It is 1 to 10 parts by weight, preferably 0.2 to 9 parts by weight.
If the amount of the water-soluble binder is less than 1 part by weight, the effect of the addition is not obtained, and if it exceeds 10 parts by weight, the strength of the molded article decreases, which is not preferable. If the amount of the dispersant is less than 0.1 part by weight, the effect of the addition is not obtained, and if it exceeds 10 parts by weight, the strength of the molded article decreases, which is not preferable.

The amount of water added is 10
It is 5 to 30 parts by weight with respect to 0 parts by weight. If the amount of water is less than 5 parts by weight, the viscosity of the ceramics slurry may increase and the fluidity may decrease, or it may be difficult for the dispersant to sufficiently exhibit the ceramics dispersion performance. On the other hand, if the amount exceeds 30 parts by weight, the ceramic particles in the slurry may settle and it may be difficult to obtain a uniform dispersion.

The optimum amount of water to be added varies within the above range depending on the particle size and particle size of the ceramic raw material powder and the type of the water-soluble binder, but generally when the apparent density of the ceramic raw material powder is large or the water-soluble binder is used. If the viscosity of the agent is small, add less water. On the other hand, when the apparent density of the ceramic raw material powder is low or the viscosity of the water-soluble binder is high, it is necessary to increase the amount of water added a little.

In the production method of the present invention, it is necessary to sufficiently mix and age the raw material mixture. The water-soluble binder, the dispersant and the water may be added to the ceramic raw material powder at the same time, but a method in which a water-soluble binder is dissolved in water in advance and then the dispersant is added to the ceramic raw material powder, or A method of dissolving or dispersing a water-soluble binder and a dispersant in water or adding a dispersion liquid to the ceramic raw material powder is a preferable method for easily obtaining a uniform dispersion of the ceramic raw material powder.

In addition to the above-mentioned components, the composition for firing the ceramic molded body of the present invention may contain other components used for firing the ceramics, such as sintering aids such as talc and powdered clay.

[0020]

According to the method of the present invention, a specific dispersant having excellent dispersibility is used in molding a molded product before firing ceramics by using the ceramic raw material powder. In other words, in tape forming with rolling rolls, tapes of any thickness can be formed simply by adjusting the clearance between the rolls, and tapes with a thickness of 0.3 mm or less, which were conventionally obtained only by the doctor blade casting method, can be easily formed. It can be molded. On the other hand, since it is possible to avoid the settling of the ceramic raw material powder particles, it is possible to manufacture a thick tape.

Further, the ceramic tape may be subjected to pattern printing before sintering, and at this time, the permeability of the printing ink becomes a problem, but since the water-soluble polymer is used as the binder in the present invention, the printing ink is used. There is no bleeding or sagging, and precise printing can be easily performed. Then, by firing this composition for a ceramic molded body, a ceramic molded body in a good state can be obtained.

[0022]

The present invention will be described below with reference to reference examples and examples.

Reference Examples 1 to 8 Production of Water-Soluble Copolymer (A) Polyoxyethylene monoallyl monomethyl ether (average molecular weight 550) was placed in a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube and a stirrer. 550 g, 98 g of maleic anhydride and 300 ml of toluene were added, and they were dissolved by sufficiently stirring under a nitrogen gas stream. After dissolution, the temperature was raised to 50 ° C., 2.0 g of t-butylperoxy-2-ethylhexanoate was added, and the temperature was raised to 70 ° C. at the same temperature.
A copolymerization reaction was carried out for 10 hours while passing nitrogen gas throughout. After the reaction, toluene was distilled off under reduced pressure at 50 ° C. to obtain a water-soluble dispersant (A) used in the present invention as a reddish brown transparent viscous liquid. As a result of measuring the molecular weight by gel permeation chromatography, the weight average molecular weight was 1
It was 5,000.

Production of Water-Soluble Copolymers (B) to (H) Dispersants (B) to (E) shown in Table 1 were produced in the same manner. Further, water was added to the dispersant (A) to hydrolyze the maleic anhydride unit of the copolymer to obtain a dispersant (F).
A 40% aqueous sodium hydroxide solution was added to the dispersant (A) to convert the maleic anhydride unit of the copolymer into a sodium salt to obtain a dispersant (G). A 30% aqueous ammonia solution was added to the dispersant (A) to convert the maleic anhydride unit of the copolymer into an ammonium salt to obtain a dispersant (H).

[0025]

[Table 1]

Reference Example 9 Production of Acrylic Resin as a Known Dispersant 1 kg of deionized water was placed in a five-necked flask equipped with a reflux condenser, a thermometer, a dropping funnel, a nitrogen gas introducing tube and a stirrer, and nitrogen gas was added. The temperature was raised to 70 ° C. under an air stream. Then 70
200 g of polyoxyethylene monomethyl methacrylate (average molecular weight 540), 50 g of acrylic acid, 500 g of methyl acrylate and 2,2'-while maintaining at ~ 75 ° C.
3.0 g of azobis [2-methyl-N-2-propenylpropionamidine] dihydrochloride was added to 20 g of deionized water.
An aqueous solution dissolved in 0 g was added dropwise over 5 hours, and further 75
Hold at 2 ° C for 2 hours. After the polymerization reaction, 30% aqueous ammonia solution was added for neutralization to obtain an acrylic resin aqueous solution. As a result of measuring the molecular weight by gel permeation chromatography, the weight average molecular weight was 160,000.

Examples 1 to 10 Using the dispersants shown in Table 1, compositions for ceramic moldings having the formulations shown below were obtained. Alumina powder (average particle size 4 μm) 100 parts by weight Talc powder 6 parts by weight Clay powder 2 parts by weight Polyvinyl alcohol * 1 6 parts by weight Dispersant 0.3 to 8 parts by weight Water 20 parts by weight * 1 …… Unitika Chemicals Co., Ltd. Made Poval UMR-10
H, polyvinyl alcohol having a degree of saponification of polyvinyl acetate of 70 to 90 mol% and a degree of polymerization of 100. The composition of these compositions, first, to the specified amount of alumina powder, talc powder and clay powder, after adding an aqueous solution of a predetermined amount of polyvinyl alcohol and a dispersant dissolved in water, after sufficiently kneading, Thickness 10 by vacuum extruder
mm and a width of 500 mm were extruded. Table 2 shows the state of the extrusion molding work and the state of the sheet.

Comparative Example 1 A sheet was produced in the same manner as in Example 1 except that the water-soluble copolymer used in Example 1 was not used. The results are also shown in Table 2.

Comparative Example 2 A sheet was manufactured in the same manner as in Example 1 except that the amount of the dispersant (A) used in Example 1 was changed to 0.05 part by weight based on 100 parts by weight of the alumina powder. The results are shown in Table 2.
Also described in.

Comparative Example 3 A sheet was produced in the same manner as in Example 1 except that 5 parts by weight of the known water-soluble acrylic resin obtained in Reference Example 9 was used as the dispersant. The results are also shown in Table 2.

[0031]

[Table 2]

From Table 2, as a dispersant used in the present invention, a copolymer of a compound represented by the general formula (1) and maleic anhydride, a hydrolyzate or a composition using a salt of the hydrolyzate in a specific amount is used. Is understood to be excellent in both extrusion conditions and the resulting sheet condition.

Example 11 The compositions of Examples 2 and 4 in Table 2 were sufficiently kneaded, and then extruded by a vacuum extruder into a sheet having a thickness of 10 mm and a width of 500 mm, and then a clearance of 5 m.
Finally, an alumina tape having a thickness of 0.2 mm was obtained while passing between rolls which were successively narrowed to m, 2 mm and 1 mm. The surface condition of each tape was uniform and glossy. The ceramics obtained by firing these tapes in a reducing flame at about 1450 ° C. had a smooth and uniform surface condition.

[0034]

EFFECTS OF THE INVENTION According to the present invention, it is possible to mold a dense and uniform ceramic compact having high strength and dimensional stability with a wide range of thickness selectivity from a very thin compact to a thick compact.

Claims (1)

[Claims] 1. A ceramic raw material powder 100 parts by weight, a water-soluble binder 1 to 10 parts by weight, and a general formula (1) as a dispersant.
Extruding a mixed composition containing 0.1 to 10 parts by weight of a copolymer of the compound represented by and maleic anhydride, its hydrolyzate or a salt of the hydrolyzate and 5 to 30 parts by weight of water. A method for producing a ceramic molded body, which comprises firing after forming or rolling roll molding. [Chemical 1] (However, AO is an oxyalkylene group having 2 to 4 carbon atoms, 50 to 100 mol% of which is an oxyethylene group, R is an alkyl group having 1 to 4 carbon atoms, and n is 4 to 150.)