JPH0380087B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a deflocculant for ceramic slurry, and more particularly to a deflocculant for ceramic slurry having excellent fluidity and storage stability. Ceramics such as pottery, porcelain, and mortarware are manufactured by appropriately blending inorganic raw materials such as natural rocks, soil, minerals, and artificial crystals, shaping them, and then heating them to high temperatures and baking them. The manufacturing process of such ceramics generally consists of the steps of clay preparation, molding, and firing, and the clay preparation is further divided into raw material preparation and base preparation. In the raw material preparation process, the raw material clay is coarsely crushed using a crusher, then mixed with water and dispersed to form a slurry, which is left to stand or flowed at a constant slow speed to produce coarse particles and specific gravity. After removing large impurities, the clay content is concentrated by dehydration. On the other hand, in the matrix preparation step, the raw materials to be blended are mixed, pulverized and mixed using a wet micropulverization method to obtain a fine and uniform matrix, and then dehydrated to prepare a slurry with a desired concentration. In the slurry preparation process, various deflocculants have traditionally been used to improve the effectiveness of impurity removal by reducing the viscosity of the slurry, and to improve productivity and economy by reducing the amount of dewatering caused by high-concentration slurry. Furthermore, in the case of cast molding, a deflocculant is also used because a highly concentrated slurry with excellent moldability and dischargeability is required. Specific examples of such deflocculants include sodium silicate, soda carbonate, polyphosphates, humic acid,
Tannic acid is also known. However, these known deflocculants are not yet sufficient in terms of peptizing properties and storage stability, and are not necessarily suitable for obtaining highly concentrated slurries with particularly good fluidity. . Therefore, the present inventors conducted intensive studies to improve this drawback of the prior art and found that a combination of a water-soluble salt of a specific polymer and a polyphosphate is extremely effective as a deflocculant for ceramic slurry. The present invention was completed based on the discovery that the present invention exists. Thus, according to the present invention, (a) a water-soluble salt of a polymer of an α,β-unsaturated dicarboxylic acid monomer or a copolymer of an α,β-unsaturated dicarboxylic acid monomer and a nonpolar vinyl monomer; (b) A deflocculant for ceramic slurry, which contains polyphosphate as an active ingredient and has a weight ratio of (a)/(b) of (95/5) to (50/50). is provided. The polymer of α,β-unsaturated dicarboxylic acid monomer or the copolymer of α,β-unsaturated dicarboxylic acid monomer and nonpolar vinyl monomer used in the present invention usually has a number average molecular weight of 500 to 100,000,
Preferably, a polymer of α,β-unsaturated dicarboxylic acid monomer having a molecular weight of 1,000 to 50,000 or the α,
It is a copolymer of a β-unsaturated dicarboxylic acid monomer and a copolymerizable nonpolar vinyl monomer.
The ratio of α,β-unsaturated dicarboxylic acid monomer in the copolymer can be selected as appropriate, but is usually 10 to 100.
mol %, preferably even 20 to 100 mol. Here, the α,β-unsaturated dicarboxylic acid monomer refers to an unsaturated dicarboxylic acid compound having a carboxyl group or an acid anhydride group, and specific examples thereof include maleic acid, fumaric acid, and itaconic acid. Examples thereof include α,β-unsaturated dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and the like. In addition, the nonpolar vinyl monomer is the α,β-
Any material that can be radically polymerized with an unsaturated dicarboxylic acid monomer may be used, and specific examples thereof include ethylene, propylene, butene, 2
-Methyl-butene-1, pentene, hexene, octene, diisobutylene, decene, cyclopentene, cyclohexene, styrene, vinyltoluene, α-methylstyrene, coumaron, indene,
Examples include methyl vinyl ether. The polymer used in the present invention is not limited in its production method, but is usually produced by radical polymerization according to a conventional method. In the present invention, the water-soluble salt of the polymer and the polyphosphate are used as a deflocculant for ceramic slurry. The salt of the polymer may be one in which at least a portion of the carboxyl groups or acid anhydride groups present within the range that allows the polymer to be water-solubilized, and in particular, 50 mol% or more forms a salt. It is preferable that the Specific examples of such salts include salts of alkali metals such as sodium, potassium, magnesium, calcium, barium, etc., or alkaline earth metal salts, ammonium salts, and amino salts. Sodium salts are preferred, and ammonium and amine salts are preferred when the presence of metal adversely affects the finish of the ceramic. The methods for producing these polymer salts are not particularly limited, and include a method in which monomers are neutralized and then polymerized, and a method in which a polymer of α,β-unsaturated dicarboxylic acid is synthesized and then a conventional method is used. Any of the neutralization methods described below may be employed. The polyphosphates used in the present invention are salts of linearly bound phosphoric acids such as sodium tripolyphosphate and sodium pyrophosphate. The usage ratio of (a) water-soluble salt of α,β-unsaturated dicarboxylic acid polymer and (b) polyphosphate is such that the weight ratio of (a)/(b) is between (95/5) and (50 /
50), preferably (80/20) to (60/40)
It is. If the value of (a)/(b) is outside the above range, the viscosity of the slurry will increase, which is undesirable. The deflocculant of the present invention may be solid or may be in the form of an aqueous solution; however, for imaging purposes, it is used in the form of an aqueous solution with a solid content concentration of 10 to 50% by weight in view of ease of handling. At this time, other deflocculants such as sodium silicate, soda carbonate, and other compounding agents may be appropriately mixed and used as long as they do not essentially impair the effects of the present invention. The method of adding the deflocculant in the present invention is not limited in any way, and any of the following methods may be used: directly adding it to ceramic raw materials, adding it to kneading water, or adding it to slurry. The proportion of peptizer used in this process is not necessarily uniform depending on the type of ceramic raw material, particle size, particle size distribution, slurry concentration, presence or absence of other deflocculants, etc. When preparing a slurry of 50 to 80% by weight, ceramic raw materials on a solid content basis
The active ingredient of the water-soluble salt of the α,β-unsaturated dicarboxylic acid polymer in the peptizer is usually 0.01 per 100 parts by weight.
-5 parts by weight, preferably 0.03-1 parts by weight. Thus, according to the present invention, it is possible to significantly reduce the viscosity of the slurry, to prepare a slurry with excellent fluidity and storage stability, and to make the slurry more concentrated or more stable than when other deflocculants are used. It is possible to reduce the viscosity. Next, the present invention will be explained in more detail with reference to Examples. The properties of the aqueous polymer solutions used in the Examples are shown in Table 1, and the test methods are as follows. In addition, parts and percentages are based on weight unless otherwise specified.

[Table] Test method (1) Slime viscosity: Measured at 12 rpm and 25°C using a Bruckfield viscometer. (2) Fluidity: The time required for 50 c.c. of slurry to be extracted by pouring slurry into a 60 mm diameter glass funnel. 5
○ indicates within minutes, △ indicates 5 to 8 minutes, and × indicates 8 minutes or more. (3) Storage stability: After placing the slurry in a sealed container and leaving it in a constant temperature bath at 50℃ for 24 hours, the viscosity and fluidity of the slurry were measured. Reference Example 1 After preparing soft clay for porcelain to a solid content concentration of 68%, samples ~ and various deflocculants were added individually to conduct a slurry deflocculant test. The results are shown in Table 2.

[Table] Reference Example 2 After preparing clay for hard porcelain to a solid content concentration of 68%, the samples shown in Table 1 and various deflocculants were individually added, and a slurry peptizer test was conducted. 3rd result
Shown in the table.

[Table] Examples 1 and 2, Comparative Examples 1 to 3 Hard porcelain clay was prepared in the same manner as Reference Example 2 to a solid content concentration of 68% using appropriate combinations of sodium tripolyphosphate and samples, and then slurry was prepared. A peptizer test was conducted. The results are shown in Table 4.

[Table] From Table 4, it can be seen that the combined use of a water-soluble salt of an α,β-unsaturated dicarboxylic acid polymer and sodium tripolyphosphate exhibits better peptizing properties than when used alone. Reference Example 3 After preparing iron-containing clay for mortarware to a slurry concentration of 58%, a slurry test was conducted by adding the sample and various deflocculants separately. The results are shown in Table 5.

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Claims (1)

[Claims] 1 (a) Water-soluble salt of a polymer of α,β-unsaturated dicarboxylic acid monomer or copolymer of α,β-unsaturated dicarboxylic acid monomer and nonpolar vinyl monomer, and (b) polyphosphate A deflocculant for ceramic slurry, comprising as an active ingredient, the weight ratio of (a)/(b) being (95/5) to (50/50).