JPS61101451A - Water-soluble ceramic 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 [Field of Industrial Application] The present invention relates to a water-soluble organic binder used for molding ceramics.

[Conventional technology and one point in between] One of the methods for molding ceramics such as alumina, silica, magnesia, and peria is to mix fine ceramic powder and a solvent, form a slurry, and draw it into a sheet using a doctor blade, for example. There is a sheet forming method that heats and dries this to obtain a ceramic sheet (green sheet, green sheet). Since the sheet thus obtained is then punched into a desired shape and then fired, an organic binder is used to maintain the shape during punching and firing.

For example, in the conventional sheet molding method, an organic binder such as butyral resin or vinyl acetate resin is dissolved in an organic solvent such as methyl ethyl ketone, butyl acetate, ethyl acetate, toluene, or alcohol. The method used is to mix the slurry for a period of time to form a slurry, defoam the air in the slurry, then draw it into a sheet onto a carrier film using a blade with a certain thickness, which is then heated and dried to form a ceramic sheet. has been done.

However, this method using a flammable solvent poses (1) harm to human health due to the organic solvent, (2) dangers such as explosion due to the use of a flammable solvent, and <3> an 8A-valent organic solvent. There were problems in terms of economy and other aspects of its use.

Therefore, methods have been proposed in which a water-soluble organic binder such as polyvinyl alcohol or polyvinyl acetate is used, or a water-based emulsion such as a polyacrylic ester or a copolymer of ethylene and 1i1f is used as a binder.

However, in these proposed methods, since water is used as a solvent, the above-mentioned (1) and (2).

Although the problem (3) has been solved, it is far from perfect, and during the long-term mixing stage with fine ceramic powder,
Due to the presence of water, ceramic fine powder tends to aggregate in the slurry, and the viscosity of the slurry deviates significantly from Newtonian flow, resulting in a sheet with a high density and smooth surface due to poor fluidity of the slurry and poor ceramic dispersibility. It cannot be said that all the problems have been solved, as it is difficult to obtain sheets that are flexible and have high mechanical strength.

In other words, regarding ceramic sheet molding, the above (
In addition to the issues in 1), (2), and <3>, (4) The surface of the ceramic sheet after drying should be smooth. (5) The formed sheet should have appropriate flexibility due to pressure layer forming and tape winding. (6) It is required that the formed sheet can be easily converted back into slurry.

However, emulsion-type organic binders are difficult to regenerate into slurry, so they are not suitable for sheet molding.

Further, it is preferable to mold the molded product using a water-soluble organic binder and water as a solvent, since it is possible to reproduce the molded product.

However, polymers containing carboxylic acids such as acrylic acid, which are often used as water-soluble organic binders, become water-soluble by neutralizing the carboxylic acid groups (carboxyl groups) with alkali or ammonium such as sodium hydroxide or potassium hydroxide. However, such neutralization has the disadvantage that a flexible sheet cannot be obtained.

In view of the above-mentioned circumstances, the object of the present invention is to use water as a solvent and have a smooth surface free from 'lk aggregates.
An object of the present invention is to provide a water-soluble organic binder from which a ceramic sheet having excellent flexibility and mechanical strength can be obtained.

[Means for Solving the Problems] That is, the present invention provides at least one α-β-union selected from acrylic acid and methacrylic ester having a hydroxy group represented by the following formula (I). 1 to 54 mol% of a saturated carboxylic acid ester, (B) 5 to 45 mol% of at least one α,β-unsaturated carboxylic acid consisting of acrylic acid and methacrylic acid, and (C) 5 to 45 mol% of at least one of the following formulas (I) and (I A copolymer produced by copolymerizing 94 to 1 mol% of at least one vinyl compound represented by [[], and at least 85 mol% of the carboxyl groups contained in the copolymer are The present invention relates to a water-soluble ceramic binder which is neutralized with a tertiary amine whose three substituents have a total of 6 to 9 carbon atoms.

General formula (1) General formula (II) General formula (II) Next, the present invention will be further explained.

The α,β-unsaturated carboxylic acid ester represented by the formula (I) of (A) of the present invention is, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxy These include group O and lumeta acrylate, and these may be used alone or in combination. This acrylic acid or methacrylic acid ester having a hydroxy group is
It is copolymerized in a copolymer with a content of 1 to 54 mol%.

Further, in the copolymer of the present invention, 5 to 45 mol% of (B) acrylic acid or methacrylic acid is copolymerized. Acrylic acid or methacrylic acid may be mixed and copolymerized.

One of the monomers to be copolymerized with the monomers (A) and (8) above is a vinyl compound (C) which is an acrylate or methacrylate represented by the above formula (n).

The acrylate or methacrylate is an ester of acrylic acid or methacrylic acid and a C-018 monoalcohol. Such alcohols include methanol, ethanol, isopropanol, n-propanol, 5ec-butanol, 1so-butanol, n-propanol,
-Flucan monools such as -butanol, 1SO-amyl alcohol, n-amyl alcohol, 1so-hexyl alcohol, n-hexyl alcohol, 2-ethylhexyl alcohol, octyl alcohol, and octadecyl alcohol. These acrylates or methacrylates may be used alone or in combination.

Furthermore, another monomer to be copolymerized is (
C) is a vinyl compound represented by the above formula (I[[). This vinyl compound includes styrene, α-methylstyrene, β-methylstyrene, α-ethylstyrene, β-
It is styrene such as ethylstyrene, α,β-dimethylmethyone, vinyltoluene, ethylstyrene, and vinylxylene, or a vinyl compound in which styrene is substituted with a methyl group or an ethyl group. These vinyl compounds may be used alone or as a mixture.

In the present invention, the α,B unsaturated carboxylic acid ester having a hydroxy group of the formula (I) as (A) is
It is necessary to copolymerize ~54 mol%.

If the amount of copolymerization of the α,β unsaturated carboxylic acid ester having a hydroxyl group is less than 1 mol %, the ceramic sheet molded product may not have satisfactory mechanical strength at dawn. On the other hand, if it exceeds 54 mol%, the strength becomes too high and cracks are likely to occur when the ceramic sheet is wound with a tape.

In the present invention, it is necessary to copolymerize 5 to 45 mol% of the α,β-unsaturated carboxylic acid (B).

If the polymerization ratio of α, β-unsaturated carboxylic acid is less than 5 mol%, the ceramic binder will not become completely water-soluble and it will be difficult to obtain a uniform slurry. When regenerating into slurry, it does not return to a uniform slurry. Moreover, if it exceeds 45 mol%, the ionicity of the ceramic binder increases,
At the stage of pulverizing and mixing with the ceramic fine powder for a long time, the fine ceramic powder coagulates with each other, making it impossible to obtain a uniform slurry, and the flexibility of the ceramic sheet molded body is completely lost, which is not preferable.

Furthermore, the copolymer of the present invention has the formula (II) as (C).
) or (III) a vinyl compound represented by formula (94)
It is obtained by copolymerizing ~1 mol%.

The copolymer of the present invention comprises the above-mentioned (A> α, β-unsaturated carboxylic acid ester having a hydroxy group), (B) α, β-unsaturated carboxylic acid ester,
- Obtained by copolymerizing an unsaturated carboxylic acid and the vinyl compound (C) using a polymerization initiator according to a conventional method.

For the copolymerization of these raw materials, conventional polymerization methods can be selected as appropriate, but it is better to use a polymerization solvent in consideration of the fact that the viscosity increases as the copolymerization progresses, and that the heat of polymerization generated by copolymerization needs to be removed. preferable. These solvents may be selected as appropriate, including methanol, ethanol, 1so-propanol, n-
Lower alcohols such as propatool, lower ketones such as acetone, methyl ethyl ketone, methyl-1so-butyl ketone, diethyl ketone, lower esters such as methyl acetate, ethyl acetate, and 1,4-dioxane, 1,3-dioxane, tetrahydrofuran. Considering the usage form of the organic binder, it is more preferable to use one that is itself water-soluble, such as cyclic ethers such as cyclic ethers. That is, in the case of the above-mentioned water-soluble solvent being mixed with ceramic fine powder to form a slurry, the polymerization solvent and the binder are mixed completely and uniformly, so that the polymerization solvent can be used without removing the polymerization solvent in advance.

The polymerization initiator may be any commonly used so-called radical polymerization initiator. For example, ketone peroxides such as methyl ethyl ketone peroxide and methylcyclohexanone peroxide, 1.1-bis(t-butylperoxy)cyclohexane, 2.2-bis(t-butylperoxy)
Peroxy ketals such as butane, hydroperoxides such as t-butyl hydroperoxide, cumenethyl O peroxide, di-t-butyl peroxide, t-butyl-
In addition to peroxides such as dialkyl peroxides such as cumyl peroxide and di-cumyl peroxide, and diacyl peroxides such as acedel peroxide and benzoyl peroxide, azobisisobutyronitrile and the like can also be used.

Polymerization can be carried out at any temperature from room temperature to 150°C, but it is industrially preferable to carry out the polymerization at a temperature below the boiling point of the polymerization solvent since there is no need for pressurization. In addition, the polymerization operation can be carried out by charging the raw materials and the solvent to be used as necessary into a polymerization reactor in advance and gradually adding the polymerization initiator, or by charging only the solvent into the polymerization reactor and gradually adding the raw materials and polymerization initiator. This can be done using the following methods. The polymerization time depends on the polymerization temperature and initiator concentration, but usually 6 to 30 hours is sufficient.

A copolymer is obtained as described above and then neutralized with a tertiary amine to make it water-soluble.

The amine to be treated is a tertiary amine in which the total number of carbon atoms contained in its three substituents is 6 or more and 9 or less. These amines may include simple alkylamines such as triethylamine, diethylbutylamine, and dimethylhexylamine, as well as those in which a hydroxyl group is introduced into an alkyl group such as hydroxyalkylamines such as triethanolamine and triisopropanolamine. The ceramic binder of the present invention can be obtained by neutralizing with these amines. If the total number of carbon atoms is 5 or less, the resulting ceramic binder may have a strong amine odor and may be practically unusable, and the ceramic sheet molded product obtained by drying may not have the flexibility to withstand winding. If it is more than 10, the water solubility of the obtained ceramic binder will be poor and it will be difficult to form a uniform slurry during pulverization and mixing.

It is important that the amine used for neutralization neutralizes 85 mol% or more of the carboxylic acid groups present in the resin. If more than 15 mol % of the carboxylic acid groups remain, the ceramic molded product will be completely assimilated and exhibit no flexibility, making it completely unsuitable for sheet molding. Although there is no problem in using a large excess of amine in the neutralization process, there are limits to its practical use due to economic efficiency, operability, odor peculiar to amines, etc. Therefore, in practice, the amount of amine used is preferably 1.2 equivalents or less for neutralizing the desired carboxylic acid group. Neutralization can be easily carried out by adding a predetermined amount of amine to the resulting resin solution. Normally, complete neutralization can be carried out in 30 minutes to 3 hours at the polymerization temperature.

Although the binder of the present invention exhibits its performance sufficiently by itself, it can be used by adding a high boiling point water-soluble polyol such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, or glycerin as a water-soluble plasticizer. It is also possible to change the flexibility of the obtained ceramic sheet molded body.

The amine-neutralized copolymer of the present invention is suitable for molding ceramics such as alumina, silica, magnesia, berea, or mixtures thereof, such as sheet molding, slurry casting, press molding, and extrusion molding. It is suitable as a binder for In particular, it is a suitable binder for forming sheets that require recycling.

[Effects of the Invention] When the binder of the present invention is used in ceramic molding, particularly in sheet molding, a ceramic green sheet with a smooth surface, flexibility, high density, and excellent mechanical strength can be obtained.

In addition, the obtained green sheets can be sufficiently recycled, which improves the yield, which is preferable.

[Example] Hereinafter, the present invention will be explained according to Examples.

All the sections described below indicate the M group section.

Example 1 In boiling isopropyl alcohol (112.5 parts),
2- and droxyethyl methacrylate (7 parts), n-butyl acrylate (66,1 part), methacrylic acid (28
, 1 part), styrene (11.25 parts) and peroxide (0.1 part) [trade name Perbutyl O1 NOF Ili] was added dropwise over 2 hours. After completion of the dropwise addition, stirring was continued at the same temperature for 5 hours. After cooling the reaction solution to room temperature, triethanolamine (48.7 parts) was added to neutralize it. Thereafter, isopropyl alcohol is distilled out from this solution under reduced pressure to obtain a water-soluble resin.

To 100 parts of alumina powder [manufactured by Sumitomo Aluminum Refining Co., Ltd., trade name: AM-211], 4 parts of the above resin and 45 parts of ion-exchanged water were added, kneaded in a ball mill for about 10 seconds to form a slurry, and then defoamed.・I made sense.

A mixed wire sheet was made from the slurry by a doctor blade method, and this was naturally dried for 2 hours, and then dried at 110° C. for 2 hours to obtain a sheet with a smooth surface.

In addition, the mechanical strength of this green sheet is JIS-7.
82.5g/#Ill when measured according to 113
+” was.

This sheet had elasticity that allowed it to be punched out, and its density was measured to be 2.58.

Further, 23 parts of ion-exchanged water was added to 50 parts of the sheet obtained above, and the mixture was milled in a ball mill at about 8:00 D! XI kneading was performed to obtain a slurry again, and after defoaming treatment, a sheet was produced by the above method. This sheet also had a smooth surface and similar flexibility. It became clear that the sheet could be recycled with a density of 2.55.

Tomoi Wataru-1 A water-soluble resin was obtained in the same manner as in Example 1. However, the polymerization solvent, isopropyl alcohol, was not removed, and the mixing operation with alumina powder was performed using the following recipe.

A sheet was prepared by kneading 100 parts of alumina powder, 7 parts of the above resin solution (4.1 parts as resin content), and 45 parts of ion-exchanged water in the same manner as in Example 1.
A similarly smooth and flexible sheet with a density of 2.61 was obtained.

Examples 3 to 6 A ceramic binder was synthesized in the same manner as in Example 1 using the reaction solvent shown in Table 1, α, β-unsaturated carboxylic acid ester, α, β-unsaturated carboxylic acid, and vinyl compound, and after neutralization. Ceramic sheets were evaluated. In either case, a recyclable, smooth, flexible, and strong sheet was obtained. The evaluation results are also shown in Table 1.

Comparative Example 1 A smooth and flexible sheet was obtained by copolymerizing and neutralizing the resin in the same manner as in Example 1 except for excluding 2-human O-oxyethyl methacrylate. Its mechanical strength was 35 g/1111, which was insufficient.

Comparative Example 2 A slurry was prepared using the resin after copolymerization and neutralization in the same manner as in Example 1, except that 2-hydroxypropyl methacrylate (66, 1 part) was used instead of n-butyl acrylate. However, it did not result in a uniform slurry. Furthermore, the sheet obtained from the slurry was also not uniform.

In Example 3, 3 parts of acrylic acid was used and copolymerization was carried out in the same manner as in Example 1, and then neutralized with 6.2 parts of triethanolamine. was.

Comparative Example 4 In Example 4, the amount of triisopropanolamine was changed to 3
After copolymerization and neutralization according to Example 4 except that the resin was used in an amount of 5 parts, a sheet was prepared using the resin, but it had poor flexibility and easily cracked.

Patent applicant Nippon Petrochemical Co., Ltd. Procedural amendment December 6, 1980 Patent application No. 222389 of 1982 2 Name of the invention Water-soluble ceramic binder 3 Person making the amendment Relationship to the case Applicant name ( Name) Nippon Petrochemical Co., Ltd. 4, Agent Address: 5-1-1 Minami Aoyama-chome, Minato-ku, Tokyo Date of amendment order (voluntary) 7. Contents of amendment (11 Specification, page 3, line 15; "Peria" in the second line from the bottom of page 16 is corrected to "Beryria."

(2) "Doctor Blade" on page 3, line 18 of the same page is replaced with "
"Doctor Blade," he corrected.

(3) "Pressure layer molding" on page 6, line 1 is corrected to "pressure lamination molding."

(Correct "ammonium" on page 6 + line 6 of 41 to "ammonium j."

(5) Correct it to "α-β-unsaturated cardic acid ester frTα, β-unsaturated calz 7 @ x ster" on page 7, line 9.

(6) “α” on page 11, lines 7-8 and 10-11
,! Unsaturated carbenoic acid ester" and "α,β-unsaturated unsaturated carbenoic acid ester" are corrected.

(7) "Assimilation" in the bottom line of page 15 is corrected to "solidification."

that's all

Claims (3)

[Claims] (1) (A) Represented by the following general formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼...(I) [R_1: H or methyl R_2: C_2 to C_4 alkyl group having a hydroxyl group] At least one α selected from hydroxyl group-containing acrylic acid and methacrylic ester,
1 to 54 mol% β-unsaturated carboxylic acid ester (B) α, β consisting of acrylic acid and methacrylic acid
- 5 to 45 mol% of at least one unsaturated carboxylic acid and (C) the following formula (II) or (III) ▲ Numerical formula, chemical formula, table, etc. are available ▼... (II) [R_3: H or methyl R_4Alkyl group of C_1 to C_1_8] ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(III) [R_5 to R_7: H, methyl or ethyl group,
and the total number of carbon atoms is 2 or less, n is an integer of 0 to 2] At least one vinyl compound represented by 94 to 1
Mol% A copolymer produced by copolymerization, in which at least 85 mol% of the carboxyl groups contained in the copolymer have three substituents with a total carbon number of 6 to 9.
A water-soluble ceramic binder characterized by being neutralized with a tertiary amine. (2) The water-soluble ceramic binder according to claim 1, wherein the vinyl compound of general formula (III) is styrene, α-methylstyrene, or vinyltoluene. (3) The water-soluble material according to any one of claims 1 and 2, wherein the tertiary amine is triethylamine, dimethylhexylamine, triethanolamine, or triisopropanolamine. Ceramic binder.