JPH0144668B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a binder for ceramics which is excellent in terms of low pollution and resource saving, and particularly to a method for producing a binder for ceramic green sheets (also referred to as green sheets). Conventionally, the production of ceramic green sheets involves
Generally, a binder such as butyral resin is dissolved in an organic solvent such as alcohol, ketone, chlorine solvent, aromatic solvent, etc., mixed with fine ceramic powder, kneaded and dispersed for a long time using a ball mill, etc., to form a slip-like product. None, after degassing, create a sheet with a certain thickness using the doctor blade method or reverse coater method.
A method of heating and drying it to make a green sheet has been adopted. However, since the method using such butyral resin uses a large amount of organic solvent, it has become a major social problem due to hygiene, pollution, and danger of explosion. Furthermore, in conjunction with the increase in costs due to the rise in oil prices, consideration has begun to be given to using water-based binders for ceramics.
For example, polyvinyl alcohol, water-soluble polyvinyl acetate, water-soluble urethane, and the like have been proposed as water-based binders. Since these binders do not use organic solvents, they are advantageous in terms of low pollution and resource saving.
The viscosity of the slip deviates significantly from Newtonian flow, the fluidity of the slip and the dispersion of the ceramic are poor, and it is difficult to obtain a green sheet with high density and a smooth surface. As a result of intensive studies, the present inventors discovered that a copolymer of unsaturated carboxylic acid ester of alkoxy(poly)ethylene glycol is useful as an aqueous ceramic binder, and completed the present invention. That is, the present invention provides (A) general formula (): [In the formula, R represents hydrogen or a methyl group, R' represents a lower alkyl group, and n represents an integer of 1 to 20] Unsaturated carboxylic acid ester of alkoxy(poly)ethylene glycol
20-60% by weight (B) Unsaturated monomer with carboxyl group
1-20% by weight (C) Unsaturated monomer with hydroxyl group
5 to 20% by weight and (D) 74% by weight or less (excluding 0% by weight) of unsaturated monomers copolymerizable with components (A), (B) and (C), totaling 100% by weight % and copolymerize the binder for ceramics. As component (A), general formula (): , R is hydrogen, R′ is a methyl group, and n is 1 to 20, methoxy (poly)ethylene glycol acrylate, R is a methyl group,
Methoxy(poly)ethylene glycol methacrylate, where R′ is a methyl group and n is 1 to 20;
R is hydrogen, R' is an ethyl group, and n is 1
~20, ethoxy(poly)ethylene glycol acrylate, R is a methyl group, R' is an ethyl group, and n is 1 to 20
Examples include ethylene glycol methacrylate. The amount of component (A) used is 20 to 60% by weight. If the amount used is less than 20% by weight, the aqueous copolymer that is the feature of the present invention cannot be obtained, and if it exceeds 60% by weight, when this copolymer is used as a ceramic binder, The elongation and strength of the obtained green sheet are low and it cannot be put to practical use. (B) Components include acrylic acid, methacrylic acid,
Examples include maleic acid, fumaric acid, itaconic acid, and the like. The amount of component (B) used is 1 to 20% by weight. If the amount used is less than 1% by weight, the fine powder will not be sufficiently dispersed when mixed with the ceramic fine powder, making it impossible to obtain a high-density and smooth green sheet. Moreover, if it exceeds 20% by weight, the elongation and strength of the green sheet will be insufficiently balanced and cannot be put to practical use. Component (C) includes hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, and the like. The amount of component (C) used is 5
~20% by weight. If the amount used is less than 5% by weight, the ceramic fine powder will not be sufficiently dispersed and a high-density and smooth green sheet will not be obtained, and the same will happen if it exceeds 20% by weight. Component (D) is always used in an amount of 74% by weight or less. Component (D) includes alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-
Alkyl methacrylates such as propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, styrene vinyltoluene, α
- Styrenic monomers such as methylstyrene, vinyl esters such as vinyl acetate and vinyl propionate,
Oxirane group-containing ethylenically unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate, vinyl cyanides such as acrylonitrile and methacrylonitrile, unsaturated amides such as acrylamide, methacrylamide, N-methylolacrylamide, and N-butoxymethylacrylamide; There are unsaturated monomers containing phosphoric acid groups such as ethyl acrylate phosphate and ethyl methacrylate phosphate.
Used alone or in combination of two or more. In some cases, it is also possible to use polyfunctional ethylenically unsaturated monomers such as ethylene glycol diacrylate in an amount of 0 to 2% by weight based on the total monomers. The copolymerization reaction of components (A) to (D) can be carried out at 50 to 150°C in the presence of a polymerization catalyst. Examples of polymerization catalysts include peroxides such as benzoyl peroxide, t-butyl peroxide, and cumene hydroperoxide, azo compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile, ammonium persulfate, potassium persulfate, etc. Persulfates can be used. The amount used is preferably 0.1 to 5% by weight based on the total amount of monomers. Further, if necessary, a molecular weight regulator such as mercaptan or carbon tetrachloride can also be used. During polymerization, organic solvents such as toluene, xylene, methyl ethyl ketone, etc. can be used. The copolymer obtained according to the present invention is used after being dissolved in an aqueous medium. The copolymer is preferably used after being neutralized to pH 6 to 8 with amines such as ammonia, trimethylamine, triethylamine, tributylamine, dimethylaminoethanol, etc., in order to prevent oxidation of the ceramic. Since the copolymer obtained according to the present invention is used after being dissolved in an aqueous medium, it is preferable to carry out the above copolymerization and/or neutralization in water or a water-soluble organic solvent. Here, examples of water-soluble organic solvents include alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, and 3-methyl-3-methoxybutanol, ethylene glycol derivatives such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, and methyl Diethylene glycol derivatives such as carbitol, ethyl carbitol, butyl carbitol, etc. can be used. A preferred solvent is isopropanol from the viewpoint of drying properties and the like. The binder for ceramics obtained by the present invention is used as an aqueous solution by dissolving it in an aqueous medium. In this case, the concentration of the binder for ceramics is
20 to 70% by weight is preferred, particularly 30 to 60% by weight. If the binder concentration is too low, it will not be possible to form it into a sheet after mixing it with the ceramic raw material. If it is too high, the viscosity will be too high and workability will be poor. Further, the aqueous medium may contain a water-soluble organic solvent, and the ratio of water/water-soluble organic solvent is 100/0.
It is preferable to adjust the ratio to ~30/70. If there is too much water-soluble organic solvent, the features of resource saving and low pollution will be reduced. In addition, in order to reduce the viscosity and prevent foaming, it is particularly preferable to mix 10 to 20% by weight of an alcoholic solvent in the aqueous medium. If necessary, a dispersant such as polyoxyethylene alkyl phenyl ether or polyoxyethylene alkyl ether may be added to such an aqueous solution. Furthermore, the binder for ceramics obtained by the present invention includes the above-mentioned acrylic resin, alkyd resin,
It can be used together with phenolic resin, vinyl acetate copolymer resin, vinyl chloride copolymer resin, rosin, maleated rosin, ceramic, nitrified cotton, cellulose derivatives, polyvinyl butyral, polyvinyl alcohol, and the like. When producing a ceramic green sheet using the aqueous solution of the ceramic binder obtained according to the present invention, it is preferable that the aqueous solution be blended in an amount of 1 to 15 parts by weight, particularly 5 to 10 parts by weight, per 100 parts by weight of ceramic. It is preferable to The ceramic binder aqueous solution obtained according to the present invention improves the dispersibility and surface smoothness of ceramics without using any or almost no organic solvents.
Ceramic green sheets with excellent density, elongation and strength can be produced, which is advantageous from the viewpoint of low pollution and resource saving. Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto. Example 1 100 g of water was charged into a 500 ml flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a gas inlet tube, and the temperature was raised to 80° C. under a nitrogen gas stream. Next, 50 g of methoxypolyethylene glycol methacrylate (n=9), 50 g of methacrylic acid
g, 10 g of 2-hydroxyethyl methacrylate,
A mixed solution of 35 g of methyl methacrylate and 2 g of azobisisobutyronitrile was uniformly dropped from the dropping funnel over a period of 2 hours. After completing the dropping, raise the temperature to 90℃,
The mixture was kept warm for 3 hours to complete polymerization. The resulting copolymer was adjusted to pH 7 with dimethylaminoethanol, and further adjusted to a heating residue of 40% with water. The viscosity of the copolymer aqueous solution at this time is the Gardner viscosity: Y-Z
It was hot. Example 2 A copolymer consisting of 50 g of methoxypolyethylene glycol methacrylate (n=4), 10 g of methacrylic acid, 10 g of 2-hydroxyethyl acrylate and 30 g of methyl methacrylate was produced in the same manner as in Example 1. The Gardner viscosity of a copolymer aqueous solution with a heating residue of 40% prepared in the same manner as in Example 1 was U-V. Example 3 Using the same equipment as in Example 1, isopropanol
100g was charged and the temperature was raised to 80°C under a nitrogen gas flow. Next, 40 g of methoxypolyethylene glycol methacrylate (n=9), 5 g of methacrylic acid,
A mixed solution of 10 g of 2-hydroxyethyl methacrylate, 45 g of methyl methacrylate, and 1 g of azobisisobutyronitrile was uniformly dropped from the dropping funnel over 2 hours. Next, this temperature was maintained for 3 hours to complete the polymerization. The resulting copolymer was adjusted to pH 7.0 with triethylamine, and further adjusted to a heating residue of 30% with water. The Gardner viscosity of the aqueous copolymer solution at this time was LM. Comparative Example 1 A copolymer consisting of 50 g of methoxypolyethylene glycol methacrylate (n=9), 15 g of 2-hydroxyethyl methacrylate, and 35 g of methyl methacrylate was produced in the same manner as in Example 1.
The Gardner viscosity of the aqueous copolymer solution adjusted to have a heating residue of 40% in the same manner as in Example 1 was Y. Comparative Example 2 A copolymer consisting of 60 g of methoxypolyethylene glycol methacrylate (n=4), 20 g of methacrylic acid and 20 g of methyl methacrylate was produced in the same manner as in Example 1. The Gardner viscosity of the copolymer aqueous solution, which was adjusted to have a heating residue of 40% in the same manner as in Example 1, was SY. Comparative Example 3 In the same manner as in Example 1, 10 g of methoxypolyethylene glycol methacrylate (n = 9), 20 g of methacrylic acid, 2-hydroxyethyl acrylate
20 g of monomer and 50 g of methyl methacrylate were polymerized, but the monomer became cloudy and separated during the dropwise addition, and no copolymer was obtained. Comparative Example 4 A copolymer consisting of 80 g of methoxypolyethylene glycol methacrylate (n=9), 5 g of methacrylic acid and 15 g of 2-hydroxyethyl acrylate was produced in the same manner as in Example 1. The Gardner viscosity of the aqueous copolymer solution adjusted to have a heating residue of 40% as in Example 1 was _Z1 . Application Example In this example, a ceramic green sheet was prepared using the aqueous copolymer solutions produced in Examples 1 to 3 and Comparative Examples 1, 2, and 4, and its properties were tested. Method for Preparing Ceramic Green Sheet A solid content of 6 g of the copolymer aqueous solution obtained in each example was added to a mixture of fine powders of 90 g of alumina (AL-45H manufactured by Showa Aluminum), 6 g of talc, and 4 g of clay. The viscosity was then adjusted to 100 boads with water. This was dispersed in a ball mill for 20 hours. Next, defoamerize, apply to a polyester sheet to a thickness of 1 mm, and leave at room temperature.
It was dried for 24 hours, then further dried at 60°C for 30 minutes and at 120°C for 30 minutes to create a ceramic green sheet. Separately, a solution consisting of 6 g of polyvinyl butyral (BL-1, trade name of Sekisui Chemical Co., Ltd.), butylbenzyl phthalate, and an organic solvent [a mixture of n-butanol/trichlorethylene = 2/8 (weight ratio)] was used. , a green sheet was created in the same manner as above. Characteristic Test The characteristics of each green sheet were tested and the results are shown in Table 1 below. Note that the evaluation of surface smoothness is based on the following criteria. ○...Good △...Slightly poor ×...Poor

【table】

[Table] As is clear from these results, when producing green sheets using the binder for ceramics obtained according to the present invention, green sheets with properties equivalent to or better than those of conventionally known organic solvent type polyvinyl butyral can be obtained. The binder obtained by the present invention can be sufficiently diluted with water alone, and an excellent green sheet can be obtained with less resources and less pollution.

Claims (1)

[Claims] 1 (A) General formula (): [In the formula, R represents hydrogen or a methyl group, R' represents a lower alkyl group, and n represents an integer of 1 to 20] Unsaturated carboxylic acid ester of alkoxy(poly)ethylene glycol
20-60% by weight (B) Unsaturated monomer with carboxyl group
1-20% by weight (C) Unsaturated monomer with hydroxyl group
5 to 20% by weight and (D) 74% by weight or less (excluding 0% by weight) of unsaturated monomers copolymerizable with components (A), (B) and (C), totaling 100% by weight % and copolymerize the binder for ceramics. 2. The method for producing a binder for ceramics according to claim 1, wherein components (A), (B), (C), and (D) are copolymerized in water and/or a water-soluble organic solvent.