JPS61163163A - Ceramic forming binder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a binder used for molding so-called ceramics such as alumina, barium titanate, ferrite, etc., and particularly to a water-based binder for molding ceramics that does not use an organic solvent.

Ceramic molding methods include dry pressing, tape molding, and extrusion molding, but the binders used in these molding methods have many drawbacks.

In the dry press molding method, a mold is filled with a ceramic composition that is granulated by spray drying a slurry prepared by mixing ceramic powder such as alumina with water, an antifoaming agent, a binder, a plasticizer, etc. This is a press molding method. As the binder used in this molding method, polyvinyl alcohol, methyl cellulose, and Na salt of carboxymethyl cellulose are generally used. However, the granules obtained using these binders are hard, and therefore the press pressure must be increased, resulting in equipment problems such as increased die wear, shortened die life, and larger press machines. There are problems and it is also difficult to mold complex shapes. By using a plasticizer such as glycerin or polyethylene glycol in combination with a binder, it is possible to soften the granules slightly and reduce the pressing pressure, but this increases the amount of solids other than the binder, making it difficult to remove the binder before firing. When removing the binder, the shrinkage becomes large, causing deformation such as blistering and distortion, and cracking, and the bonding force decreases, resulting in weak mechanical strength, which is undesirable.

Furthermore, during storage after molding, the plasticizer may bleed onto the surface or volatilize, causing brittleness. In addition, the Na salts of polyvinyl alcohol, methylcellulose, and carboxymethylcellulose have poor thermal decomposition properties, and a large amount of ash remains, including carbon and alkali metals such as Na, which cannot be decomposed or burned out in a single debinding step, resulting in blistering during the firing process. , causing deformation such as cracks and cracks.
When used as electronic components such as 1C substrates and IC packages, it causes loss of electrical properties such as electrical insulation. In general, these binders are highly hygroscopic, and mechanical strength decreases due to moisture absorption after press molding, causing breakage during storage or handling before binder removal.

In the tape molding method, a slurry prepared by mixing ceramic powder with an organic solvent, a dispersant, a plasticizer, an organic solvent binder, etc. is cast onto a carrier film with the thickness adjusted using a doctor blade, etc., and then dried. This is a method of forming into a tape-shaped green sheet.

Toluene, trichloroethylene, isopropyl alcohol, ethyl alcohol, etc. are used as organic solvents, but there are many problems such as the risk of explosion or fire due to ignition, odor during molding, toxicity to the human body, and pollution caused by evaporated organic gas during drying. There is a problem with this. In addition, explosion-proof equipment, waste gas treatment equipment,
It will also be necessary to install solvent recovery equipment. Polyvinyl butyral is generally used as an organic solvent-based binder, but it has poor thermal decomposition properties and has the same problems as binders for press molding due to ash content such as carbon and Na remaining after binder removal. In addition, a plasticizer such as a phthalate ester must be used, and the molded product becomes brittle due to breathing or volatilization of the plasticizer on the surface during storage after molding.

The extrusion molding method uses ceramic powder, water, dispersant, lubricant,
This is a method in which a binder, a plasticizer, etc. are mixed and the mixture is extruded using an extrusion molding machine. Methyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol are generally used as binders, but they have poor thermal decomposition properties, and the same problems as binders for press molding occur due to residual carbon and Na content after binder removal. .

In view of the current situation, the present inventor has conducted extensive research to solve these problems of binders in press molding methods, tape molding methods, extrusion molding methods, etc., and has found that
Consists of a (meth)acrylic acid alkyl ester having ~20 alkyl groups and a (meth)acrylic acid alkoxyalkyl ester having an alkylene group having 1 to 4 carbon atoms and having an alkyl group having 1 to 4 carbon atoms. 40 to 95% by weight of at least one monomer selected from the group, 5 to 60% by weight of an amino group-containing monomer, and 0 to 55% by weight of a monomer copolymerizable with these and having no carboxyl group.
(However, the total of all monomers is 100% by weight.)
It was discovered that a water-based ceramic molding binder obtained by copolymerizing the above-described materials satisfies these requirements, and the present invention was completed.

In other words, the present invention reduces the press pressure in the press molding method,
Improved moldability, hygroscopicity, and thermal decomposition: In the tape molding method, the transition from a solvent-based system to a safe and hygienic water-based system improved thermal decomposition; in the extrusion molding method, improved thermal decomposability and improved moldability It is an object of the present invention to provide a binder for forming ceramics, each of which brings about improvements.

In addition, in the following description, (meth)acrylate shall represent acrylate and/or methacrylate.

Examples of the (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms used in the present invention include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, and n-butyl (meth)acrylate. > Acrylate, isobutyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, etc. can be used. Contains an alkylene group and an alkyl group having 1 to 4 carbon atoms (meth)
Examples of acrylic acid alkoxyalkyl esters include methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxybutyl (meth)acrylate, butoxyethyl (meth)acrylate etc. can be used.

Such (meth)acrylic acid alkyl esters having an alkyl group having 1 to 20 carbon atoms and (meth)acrylic acid having an alkylene group having 1 to 4 carbon atoms and an alkyl group having 1 to 4 carbon atoms At least one monomer selected from the group consisting of acid alkoxyalkyl esters must be used in a proportion ranging from 40 to 95% by weight of the total copolymerized monomer ioo weight%. If the ratio is low, less than 40%, the thermal decomposition property will be reduced, the press pressure will increase due to the hardness, and the binding strength as a binder will be reduced. If the ratio exceeds 95% by weight, the hydrophilicity decreases, the amount of wetting and adsorption to ceramic powder decreases, the binding strength as a binder decreases, and the sheet may crack in the tape molding method. Molding may become impossible.

Examples of amino group-containing monomers include aminoethyl (
Primary amine monomers such as methacrylate, aminoethyl (meth)acrylamide, allylamine, and N
- Secondary amine monomers such as methylaminoethyl (meth)acrylate, N-phenylaminoethyl (meth)acrylate, N,N-dimethylamine ethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide , N-vinyl-2-pyrrolidone, N-
Tertiary amine monomers such as vinylpyrrolidine, N,
Alkyl halides such as N-dimethylaminoethyl (meth)acrylate and diallylamine, quaternized products quaternized with dimethyl sulfate, etc. can be used, and one or more of these can be used in combination. can. Moreover, the monomers of primary amine, secondary amine, and tertiary amine may be used after being neutralized in advance with an inorganic or organic acid such as sulfuric acid, hydrochloric acid, acetic acid, or oxalic acid.

Such amino group-containing monomers must be used in a proportion ranging from 5 to 60% by weight based on 100% by weight of the total copolymerized monomer. If the ratio is less than 5% by weight, the hydrophilicity decreases, the wettability to ceramic powder and Wffi decrease, and the binding strength as a binder decreases. If the ratio exceeds 60% by weight, the thermal decomposition property will be lowered, the press pressure will increase due to hardness, and the binding strength as a binder will be lowered. Hygroscopicity also increases.

Monomers that can be copolymerized with these and do not have a carboxyl group include (meth)acrylonitrile, (meth)
Acrylamide, N-methylol (meth)acrylamide, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, glycerol (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, styrene, α-methyl Styrene, vinyl acetate, vinyl chloride, ethylene, etc. can be used.

Such a copolymerizable monomer having no carboxyl group is used as necessary, and is present in a proportion of 0 to 55% by weight based on 100% by weight of the total copolymerizable monomer.

When the ratio exceeds 55% by weight, the ratio of at least one monomer selected from the group consisting of (meth)acrylic acid alkyl ester and (meth)acrylic acid alkoxyalkyl ester and the amino group-containing monomer is 40% by weight.
In the latter case, the amount is less than 5% by weight, and the above-mentioned disadvantages occur. The polymerization method for obtaining the water-based ceramic molding binder of the present invention is not particularly limited;
Conventionally known polymerization methods can be used.

The ceramic molding binder of the present invention thus obtained may be used as a binder as it is, or if a primary amine, secondary amine or tertiary amine monomer is used as the amino group-containing monomer, hydrochloric acid, sulfuric acid, etc. It may be used after being neutralized with an inorganic acid such as or an organic acid such as acetic acid or oxalic acid, or quaternized with an alkyl halide, dimethyl sulfate, or the like.

The ceramic molding binder of the present invention reduces press pressure, improves moldability, and moisture absorption in press molding; transitions from solvent-based to safe and sanitary water-based, and improves thermal decomposition properties in tape molding; extrusion molding In this case, improvements in thermal decomposability and moldability can be achieved.

The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, all parts in the examples indicate parts by weight, and all percentages indicate weight %.

Example 1 (Synthesis of binder) In a separable flask equipped with a stirrer, thermometer, cooling tube, nitrogen introduction tube, mixing monomer dropping funnel, and polymerization initiator dropping funnel, 170 parts of distilled water and polyoxyethylene nonylphenyl as an emulsifier were added. Ether (HLB 18
．． 2. (manufactured by Kao Soap ■) was charged, and nitrogen was introduced from the nitrogen introduction tube to create a nitrogen atmosphere inside the flask. Next, 100 parts of a mixed monomer containing 55 parts of n-dodecyl methacrylate, 20 parts of ethyl acrylate, 10 parts of vinyl acetate, and 15 parts of dimethylaminoethyl acrylate were charged into the mixing monomer dropping funnel, and a 2% aqueous ammonium persulfate solution was added to the polymerization initiator dropping funnel. I made 20 copies. While adjusting the internal temperature of the flask to 80°C, add the additive and polymerization initiator dropwise to the mixture over 2 hours, heat roughly at 80°C for 1 hour, cool, and neutralize with acetic acid to obtain a solid content concentration of 35%. A binder for ceramic molding was obtained. The ash content and Na content of this binder were measured and the results are shown in Table 1.

For the ash content, put a dry binder in a platinum crucible and
It was incinerated in an electric furnace at 50° C. in an air atmosphere for 2 hours, and its weight was measured.

The Na content was measured by dissolving a part of the above ash with mineral acid and using an atomic absorption spectrophotometer.

Example 2 (Molding of ceramics) 100 parts of alumina (AL-160SG, average particle size 0.4μ, manufactured by Showa Light Metal), 40 parts of distilled water, 0 dispersant (Aqualink NL, manufactured by Nippon Shokubai Kagaku Kogyo I), 2 parts and 20 parts of the ceramic molding binder with a solid content concentration of 35% obtained in Example 1 were mixed in a ball mill for 24 hours, and the resulting slurry was spray-dried to an average particle size of 100 μm.
granules were obtained.

Fill this granule into a mold, 500 to 9/ci11000
Kg/ci and 1500Kq/cIA press pressure to obtain a thickness of 311II and a width of 10. w, length 30
A molded product with a similar shape was obtained. The releasability from the mold and the surface smoothness of the molded product were good. The green density, bending strength, and hygroscopicity of these molded articles were measured, and the results are shown in Table 1.

The bending strength was measured using an Instron strength test model 111102 at a span width of 20 and a head speed of 0.50.

The evaluation of hygroscopicity was based on the weight increase rate after humidifying a molded product obtained at a press pressure of 1000 Kg/Cd at 20°C and 65% RH for 24 hours, and the weight increase when it was further humidified at 20°C and 95% RH for 24 hours. The rate was measured.

Comparative Example 1 Molding was carried out in the same manner as in Example 2, except that 7 parts of polyvinyl alcohol (GL-05, manufactured by Nippon Gosei Kagaku ■) was used as a binder for 100 parts of alumina (AL-1608G). Regarding the product, green density, bending strength,
Hygroscopicity was measured.

Incidentally, the ash content and Na content of polyvinyl alcohol were also measured. The ash content and Na content are considerably higher than those of the ceramic molding binder of Example 1. In addition, the press pressure had to be higher than in Example 2 to obtain the same green density. Furthermore, the bending strength at the same green density is low;
Hygroscopicity was high. These results are shown in Table 1.

Comparative Example 2 Polymerization and polymerization were carried out in the same manner as in Example 1 and Example 2, except that 100 parts of a mixed monomer consisting of 15 parts of n-dodecyl methacrylate, 5 parts of ethyl acrylate, 10 parts of vinyl acetate, and 70 parts of dimethylaminoethyl acrylate were used. The molding was carried out, and the ash content and Na content of the obtained binder, as well as the green density, bending strength, and hygroscopicity of the molded product were measured, and the results are shown in Table 1. The ash content was higher than in Example 1, the hygroscopicity was higher than in Example 2, the pressing pressure was also higher, and the bending strength was lower.

Example 3 (Synthesis of binder) Polymerization was carried out using the same apparatus as in Example 1. First, add 105 parts of distilled water and 2 parts of polyoxyethylene nonylphenyl ether (HLB 16.0, manufactured by Sanyo Chemical Industries, Ltd.) to a flask.
I prepared a section. Next, the mixed monomer was added dropwise into the funnel; 70 parts of methyl acrylate, 1 part of 2-methoxyethyl acrylate.
5 parts of dimethylaminoethyl methacrylate and 15 parts of dimethylaminoethyl methacrylate.
I have prepared 0 copies. While adjusting the internal temperature of the flask to 80°C, the mixed monomer and polymerization initiator were each added dropwise over 2 hours, heated at 80°C for 1 hour, and then cooled to obtain a binder for ceramic molding with a solid content concentration of 45%. Ta. The ash content and Na content of this binder are shown in Table 2.

Example 4 (Molding of ceramics) 98 parts of alumina (AL-1603G), 2 parts of MgO, 40 parts of distilled water, 0 or 2 parts of dispersant (Aqualink NL), and the solid content concentration obtained in Example 3: 45% 30 parts of a ceramic molding binder were mixed in a ball mill for 24 hours,
The obtained slurry was degassed under reduced pressure and then cast to a thickness of 1.5 m on silicone-coated release paper. Next, the temperature was increased from 60°C to 120°C at a temperature increase rate of 1°C/min, and the moisture content was 0.
．． A tape-shaped flexible green sheet was created by drying to 1% or less. The green density and tensile properties of the sheet were measured.

The tensile properties of the sheet were determined using dumbbell type 3 (JISK6301
), pulled at a pulling speed of 0.5 rx/min,
The elongation and strength at break were measured. These results are shown in Table 2.

Comparative Example 3 98 parts of alumina (AL-1603G), 2 parts of MgO, 13.5 parts of polyvinyl butyral (3000K, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a binder, 5 parts of n-octyl phthalate as a plasticizer, and glyceryl trioleate as a dispersant. 0.5 part and trichlorethylene 40 as solvent
and 20 parts of ethyl alcohol were mixed in a ball mill for 24 hours, and a green sheet was prepared in the same manner as in Example 4.
Green density and tensile properties were measured. The ash content and Na content of polyvinyl butyral were also measured. These results are shown in Table 2. Both the ash content and the Na content were considerably higher than that of the ceramic molding binder of Example 3.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 3, except that 100 parts of a mixed monomer consisting of 80 parts of methyl acrylate, 18 parts of 2-methoxyethyl acrylate, and 2 parts of dimethylaminoethyl methacrylate was used, and the obtained ceramic molding material was An attempt was made to obtain a green sheet using a binder in the same manner as in Example 4, but the sheet developed cracks due to drying.

Example 5 (Synthesis of binder) Polymerization was carried out using the same apparatus as in Example 1. Pour 400 parts of distilled water into a separable flask, add 45 parts of methyl acrylate and polyethylene glycol monomethacrylate (PE-350, manufactured by NOF ■) to a mixing monomer dropping funnel.
45 parts of dimethylamine ethyl methacrylate, and 100 parts of a mixed slurry consisting of 10 parts of dimethyl sulfate quaternized dimethylamine ethyl methacrylate were charged, and a polymerization initiator dropping funnel was charged with 20 parts of a 5% 1a1 ammonium aqueous solution. Next, while adjusting the internal temperature of the flask to 75°C, the mixed monomer and polymerization initiator were added dropwise over 2 hours each, heated at 80°C for an additional 30 minutes, and then cooled. Got the binder. The ash content and Na content of this binder are shown in Table 3.

Example 6 (Molding of ceramics) 100 parts of barium titanate (KYORIX A, manufactured by Kyoritsu Ceramic Materials ■), 40 parts of distilled water, 0.2 parts of dispersant (Aqualic NL), 2 parts of stearic acid as a lubricant, and 15 parts of the ceramic molding binder obtained in Example 5 and having a solid content concentration of 20% were mixed using a universal mixer (SDMV type, manufactured by Sanei Seisakusho). Next, the mixture was extruded into a rod shape with a diameter of about 5M using a continuous kneader (manufactured by Kurimoto Iron Works).

The obtained extruded product was heated from 60°C at a heating rate of 1°C/min.
The temperature was raised to 20° C., and then heated at 120° C. for 30 minutes to dry to a moisture content of 0.1% or less.

After drying, it was cut and the upper and lower circular planes were polished with sandpaper to form a cylinder with a length of 10 #, and the crushing strength in the longitudinal direction was measured. The results are shown in Table 3. The crushing strength was measured using a Honya type hardness meter (manufactured by Mizuya Seisakusho).

Comparative Example 5 Extrusion molding was performed in the same manner as in Example 6 using 3 parts of methyl cellulose (Marboros M-6001 manufactured by Matsumoto Yushi Seiyaku @ J) as a binder to barium titanate (KYORIX A > 100 parts), and then crushed. The strength was measured.The ash content and Na content of methyl cellulose were also measured, and the results are shown in Table 3. Compared to the ceramic molding binder of Example 5, both the ash content and Na content were higher.

Comparative Example 6 25 parts of methyl acrylate, polyethylene glycol monomethacrylate (PE-350, manufactured by NOF ■) 73
Polymerization was carried out in the same manner as in Example 5, except that 100 parts of a mixture of 1 part and 2 parts of dimethyl sulfate quaternized dimethylaminoethyl methacrylate was used to obtain a binder for molding ceramics, which was used for extrusion molding. In addition, the ash content and Na content of this binder and the crushing strength of the molded product were measured. The results are shown in Table 3. The crushing strength was lower than that of Example 6.

Chapter 1 Table ■ I-/, t 1′.

Bu Table 2 [knee ■ 11"

Claims (1)

[Scope of Claims] 1. (Meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms and an alkylene group having 1 to 4 carbon atoms, having an alkyl group having 1 to 4 carbon atoms; 40 to 95% by weight of at least one monomer selected from the group consisting of (meth)acrylic acid alkoxyalkyl esters, 5 to 60% by weight of amino group-containing monomers, and a monomer copolymerizable with these and having no carboxyl group. A ceramic molding binder obtained by copolymerizing 0 to 55% by weight (however, the total of all monomers is 100% by weight).