JP3429558B2 - Dispersant and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant, particularly a dispersant used in the electric and electronic fields and a method for producing the same. More specifically, the present invention relates to a dispersant for the electric and electronic fields, which is used in the production of electroceramics such as ferrite and ceramic capacitors, and in the production of phosphor slurries for color televisions and cathode ray tubes, and a method for producing the same.

[0002]

2. Description of the Related Art As a dispersant for electric and electronic products such as electroceramics, alkali (earth) metals such as Na, K, Ca, and Mg that remain as ash during the sintering process are used as a part of the components. It has been pointed out that the dispersant contained therein has a problem in electrical characteristics. Therefore, a dispersant neutralized with ammonia or alkanolamine (Japanese Patent Laid-Open No. 59-22639 and Japanese Patent Laid-Open No. 61-101).
No. 449, etc.) has been proposed and used.

[0003]

A polyacrylic acid salt prepared by neutralizing polyacrylic acid, which has been proposed as a dispersant for use in electroceramics, etc., with ammonia, alkanolamine, etc., is an electrical material derived from an alkali (earth) metal. However, it has a drawback in dispersibility, which is the basic performance of the dispersant. That is, since polyacrylic acid is neutralized with a weak base such as ammonia or alkanolamine, dissociation of carboxylate ions in an aqueous solution is not sufficient, resulting in dispersion of industrially used Na salt of polyacrylic acid. There was a problem that the dispersion performance was lower than the performance. In addition to the problem of dispersion performance, there is a problem in the manufacturing process that minimizes halogen elements such as fluorine and chlorine, which are problems in the electric and electronic fields.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a quaternary ammonium salt-based dispersant, which is different from the conventional one, does not cause deterioration in dispersion performance. In addition, Na, which causes deterioration of electrical characteristics,
The present invention has been accomplished by finding an excellent dispersant capable of minimizing alkali (earth) metals such as K, Ca, Mg, and halogen elements such as fluorine and chlorine. That is, the present invention is
A dispersant comprising a quaternary ammonium salt (B) of a polymer (A) comprising a (meth) acrylic acid (a) as a constituent unit;
And a quaternary ammonium salt of a polymer (B) obtained by an anion exchange reaction between a quaternary ammonium carbonate (C) obtained by reacting a tertiary amine with a carbonic acid diester and a polymer (A). Is a method for producing a dispersant.

The polymer (A) composed of (meth) acrylic acid (a) as a constituent unit of the present invention includes (meth) acrylic acid (a) and, if necessary, other vinyl monomer (b).
And a copolymer thereof. Examples of the other vinyl monomer (b) include (meth) acrylic acid ester {for example, methyl (meth) acrylic acid ester, ethyl (meth) acrylic acid ester, butyl (meth) acrylic acid ester, propyl (meth) acrylic acid ester. Ester, cyclohexyl (meth) acrylic acid ester, etc .; α, β-unsaturated carboxylic acid other than (meth) acrylic acid {for example, maleic acid, itaconic acid, crotonic acid, etc.}; α, β-unsaturated carboxylic acid amide { For example, (meth) acrylamide, itaconic acid amide, crotonic acid amide, etc .; other vinyl monomers {eg, vinyl acetate, vinyl propionate, vinylpyrrolidone, etc.} and the like, and mixtures thereof. Among these other vinyl monomers (b), preferred are (meth) acrylic acid esters and α, β-unsaturated carboxylic acids other than (meth) acrylic acid.

The polymer (A) of the present invention is composed of (meth) acrylic acid (a) and, if necessary, other vinyl monomer (b). As the composition ratio of the polymer (A), the (meth) acrylic acid (a) is 40 to 100% by weight, and the other vinyl monomer (b) is 0 to 60% by weight,
Preferably, (a) is 70 to 100% by weight, and the other vinyl monomer (b) is 0 to 30% by weight. The composition of the polymer (A) is preferably a polymer with (meth) acrylic acid and optionally a (meth) acrylic acid ester and an α, β-unsaturated carboxylic acid other than (meth) acrylic acid. A particularly preferable composition is a homopolymer or copolymer of acrylic acid or methacrylic acid. The weight average molecular weight of the polymer is usually 1,000 to 50,000.

A method for obtaining the polymer (A) of the present invention may be a generally used polymerization method and is not particularly limited. For example, a monomer such as (meth) acrylic acid containing a polymerization initiator is added to a solvent such as water or water-soluble alcohol (methanol, ethanol, propyl alcohol, butyl alcohol, etc.) at a predetermined temperature for several hours. It can be obtained by carrying out solution polymerization.

Examples of the polymerization initiator include azo type initiators, peroxide type initiators and hydroperoxide type initiators. The amount of the initiator used is 0.001 to 5% by weight based on the weight of all the monomers. These polymerization initiators are
Depending on the difficulty of decomposition, it is necessary to properly select the polymerization temperature, and the polymerization is usually carried out by selecting in the range of 0 to 180 ° C. The polymerization time is 1 to 24 hours.

The quaternary ammonium constituting the quaternary ammonium salt (B) of the present invention is a quaternary compound of a tertiary amine.
Examples of the tertiary amine include aliphatic amines (eg, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, diethyl-1-propylamine, etc.); alicyclic amines (eg, N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-methylhexamethyleneimine, N-ethylhexamethyleneimine, N-methylmorpholine, N-butylmorpholine, N, N'-dimethylpiperazine, N, N '-Diethylpiperazine, 1,5
-Diazabicyclo [4,3,0] -5-nonene, 1,8
-Diazabicyclo [5,4,0] -7-undecene etc.); nitrogen-containing heterocyclic aromatics (for example, pyridine, 4-
Dimethylaminopyridine, picolines, N-methylimidazole, N-methylbenzimidazole, quinoline,
4,4′-dipyridyl and the like). Of these, aliphatic amines are preferable, and trimethylamine and triethylamine are particularly preferable.

Quaternary ammonium salt (B) in the present invention
The content of halogen atom and alkali (earth) metal contained in each is 10 ppm or less, preferably 3 pp
m or less. When the content of 10 ppm is rubbed, serious problems for precision electric and electronic devices occur, such as deterioration of electric characteristics such as noise generation, generation of rust and performance deterioration in long-term durability test.

The method for producing the quaternary ammonium salt (B) of the present invention includes quaternary ammonium hydroxide and a polymer (A).
There is a method of reacting with, but with this method, a large amount of a halide and an alkali (earth) metal are mixed in during the production of quaternary ammonium hydroxide, and this removal is difficult. The dispersant of the present invention comprises a quaternary ammonium carbonate (C) obtained by reacting a tertiary amine capable of avoiding mixing of a halide and an alkali (earth) metal with a carbonic acid diester, and a polymer (A). Is particularly preferred.

Examples of the tertiary amine and the polymer (A) used in the production method of the present invention include those mentioned above.

Examples of the carbonic acid diester used in the production method of the present invention include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, dipropyl carbonate, and the like, with preference given to dimethyl carbonate having a small number of carbon atoms in the alkyl group.

Specific examples of the quaternary ammonium salt (B) of the present invention include tetraalkylammonium salts.
When the four alkyl groups constituting the quaternary ammonium are the same, the crystallinity of the obtained quaternary ammonium organic acid salt is high, the solubility in the resin component or the solvent is lowered, and the workability is lowered. Therefore, it is preferably a tetraalkylammonium salt having not all the same alkyl groups but different alkyl groups. Particularly preferred is a tetraalkylammonium salt in which one alkyl group is a methyl group and the other three alkyl groups are alkyl groups other than the methyl group.

The molar ratio of the tertiary amine to the carbonic acid diester in the production method of the present invention is 1: (0.3 to 4.0). The reaction solvent may be used if necessary, and examples thereof include methanol and ethanol. The reaction temperature is 30 to 150 ° C.

The anion exchange reaction between the quaternary ammonium carbonate (C) and the polymer (A) may be carried out in the presence or absence of a solvent, and the generated carbon dioxide gas is removed from the reaction system at appropriate times to complete the reaction. The quaternary ammonium salt (B) of the invention can be obtained. After the reaction, the reaction solvent is distilled off if necessary, and a solid dispersant, an aqueous solution or an organic solvent (for example, methanol, ethanol, acetone, (poly) ethylene glycol, (poly) propylene glycol, γ-butyrolactone, N-methylpyrrolidone, etc. } And can be used as a liquid dispersant.

In the anion exchange reaction between the quaternary ammonium carbonate (C) and the polymer (A), the polymer (A) 0.8 to 0.8 to 1 mol of the quaternary ammonium carbonate (C).
5.0 mol is preferable, and a mixture in which an anion exchange reaction is performed at a molar ratio such that the pH of a 10 wt% aqueous solution of the obtained quaternary ammonium organic acid salt is 6.5 to 7.5 is particularly preferable.

Specific examples of the use of the dispersant of the present invention include the production of ceramic green sheets and phosphor slurries for television cathode ray tubes. In any case, the dispersant of the present invention can be added to the target slurry and mixed by using a kneader such as a ball mill.

[0019]

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to these examples. Chlorine in the examples is JIS-1.
The measurement was performed according to the inorganic chloride measuring method described in 527.
Further, sodium was measured using an ICP emission spectrophotometer manufactured by Perkin Elmer Inc. including other alkali (earth) metals.

Example 1 Triethylamine (1 mol) was added to a stirring autoclave,
Dimethyl carbonate (1.5 mol) and methanol (2.0 mol) as a solvent were charged and reacted at a reaction temperature of 110 ° C. for 12 hours to obtain a methanol solution of methyltriethylammonium methyl carbonate. Acrylic acid / maleic acid copolymer (molar ratio 100/30, weight average molecular weight 50
00) in 40% by weight aqueous solution of the above methanol solution of methyltriethylammonium methyl carbonate
Was set to be 7.0. Carbon dioxide gas and methanol were removed, and water was added to obtain a 35 wt% aqueous solution of acrylic acid / maleic acid copolymer / methyltriethylammonium salt (dispersant-1). Dispersant-1 has a chlorine content of 1 ppm or less and a sodium content of 1 pp.
It was m or less. No other halogens or alkali (earth) metals were found.

Example 2 The same operation as in Example 1 was carried out except that trimethylamine was used instead of triethylamine to obtain a 35% by weight aqueous solution of acrylic acid / maleic acid copolymer / tetramethylammonium salt (dispersant-2). It was Dispersant-2 had a chlorine content of 1 ppm and a sodium content of 1 ppm or less. Other halogens and alkalis (earth)
No metal was found.

Example 3 A 40% by weight aqueous solution of an acrylic acid polymer (weight average molecular weight of 4000) was added with a methanol solution of methyltriethylammonium methyl carbonate synthesized in Example 1 to pH.
Was set to be 7.0. By removing carbon dioxide and methanol and adding water, a 40 wt% aqueous solution of acrylic acid / methyltriethylammonium salt (dispersant-
3) was obtained. Dispersant-3 had a chlorine content of 1 ppm or less and a sodium content of 1 ppm or less. No other halogens or alkali (earth) metals were found.

Comparative Example 1 Acrylic acid / maleic acid copolymer (molar ratio 100/3
0, a 40 wt% aqueous solution of weight average molecular weight 5000),
Neutralization was carried out by charging with a 50% by weight aqueous solution of sodium hydroxide so as to have a pH of 7.0. A 35 wt% aqueous solution of acrylic acid / maleic acid copolymer / Na salt (dispersant-A) was obtained by adding water. Dispersant-A had a chlorine content of 120 ppm and a sodium content of 6.8% by weight.

Comparative Example 2 Ammonia gas was blown into a 40% by weight aqueous solution of an acrylic acid polymer (weight average molecular weight 4000) so that the pH of the aqueous solution would be 7.0. Then, water was added to obtain a 35 wt% aqueous solution of acrylic acid polymer / ammonium salt (dispersant-B). Dispersant-B had a chloro content of 6 ppm and a sodium content of 4 ppm.

Dispersion performance evaluation 100 parts by weight of alumina, 25 parts by weight of water, and a dispersant (1, 2, 3, A, B) were charged into a ball mill and 10
After kneading for a time, the viscosity of the slurry was measured and the results shown in Table 1 were obtained.

[0026]

[Table 1]

As can be seen from Table 1, the slurry using the dispersant of the present invention has low viscosity and excellent dispersibility. Further, since no alkali (earth) metal typified by sodium and calcium is contained, no electrical trouble was found in the product. On the other hand, the dispersant-A prepared in Comparative Example 1 has good dispersibility, but since it contains sodium as one component, it remains in the product without disappearing even after firing, so that it can be used as a capacitor. Could not show basic electrical performance. On the other hand, although the dispersant-B prepared in Comparative Example 2 had good electric performance, it had a high viscosity because it was neutralized with ammonia and had a problem in the dispersion performance.

[0028]

INDUSTRIAL APPLICABILITY The dispersant of the present invention can be used not only for electroceramics and phosphor slurries, but also for many applications requiring the dispersant in the electric and electronic fields without impairing the electrical characteristics.

Claims (4)

(57) [Claims] 1. A dispersant comprising a quaternary ammonium salt (B) of a polymer (A) comprising a (meth) acrylic acid (a) as a constituent unit. 2. The dispersant according to claim 1, wherein the halogen atom and the alkali (earth) metal contained in the quaternary ammonium salt (B) of the polymer (A) are each 10 ppm or less. 3. The dispersant according to claim 1, wherein the quaternary ammonium salt (B) of the polymer (A) is a tetraalkylammonium salt of the polymer (A). 4. An anion exchange reaction between a quaternary ammonium carbonate (C) obtained by reacting a tertiary amine with a carbonic acid diester and a polymer (A) composed of (meth) acrylic acid (a) as a constituent unit. A method for producing a dispersant comprising a quaternary ammonium salt of a polymer (B), which is obtained by