JPS60262862A - Composition containing inorganic pigment dispersed therein - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has uniform dispersibility, gives dispersion having good flow characteristics, has good dimensional stability during drying and a high binder effect and gives moldings having a high strength, consisting of an inorg. pigment, a specified partially saponified polyvinyl acetate resin and water. CONSTITUTION:A compsn. contg. an inorg. pigment dispersed therein consists of 100pts.wt. inorg. pigment, 0.5-100pts.wt. partially saponified polyvinyl acetate resin having an average degree of polymn. of 30-2,000 and a degree of saponification of 5-60mol% and 10-400pts.wt. water. The compsn. has uniform dispersibility, gives dispersion having good flow characteristics, has good dimensional stability during drying and a high binder effect and gives moldings having a high strength. The compsn. is suitable for use as paints, paper coatings, adhesives or slurry for ceramic molding.

Description

[Detailed description of the invention] The present invention relates to an inorganic pigment dispersion composition.

Traditionally, 8M pigment-free dispersion compositions consisting of inorganic pigments, water-soluble polymers such as polyvinyl alcohol, and water have been widely used in paints, adhesives, etc., and recently their use as slurry for molding ceramics has increased. are doing. A water-soluble polymer such as polyvinyl alcohol contained in this composition is added as a binder and/or a pigment dispersant, and in addition to polyvinyl alcohol, suns such as carboxymethyl cellulose and sorbitol are used.

Recently, for these dispersion compositions, improvements in drying speed,
It is desired to increase the concentration of the dispersion liquid from the viewpoint of forming a crack-free film or improving the dimensional stability of molded products.
Furthermore, high-concentration dispersions also have good fluidity1wi
The absolute conditions are that the ingredients are uniformly dispersed and that the binder has a large effect. however,
When polyvinyl alcohol or the like is used as a binder or dispersant, these polymers are water-soluble and have a high viscosity, so increasing the concentration of the dispersion will rapidly increase the viscosity, causing the dispersion to lose its fluidity. It was extremely difficult to convert. Furthermore, although there is no problem with the use of sugars when increasing the concentration, the uniform dispersibility of the RN material is poor, and the binder effect on inorganic pigments is extremely low, resulting in problems such as weak strength of the formed film or molded product. It was something that remained. Also.

Even if polyethylene, polypropylene, etc. which are insoluble in water are used, it is only a simple mixing and the pigment cannot be uniformly dispersed5, and the binder effect is negligible. In addition, a method of dispersing inorganic pigments using surfactants has been proposed, and a highly concentrated dispersion with good uniform dispersibility can be obtained, but the binder strength against the filler is extremely poor, making it difficult to use in paints, paper processing, etc. However, it is very difficult to use it as an adhesive or a slurry for ceramic molding.

The present inventors have overcome these problems and created an inorganic pigment dispersion that has a uniform dispersion, excellent fluidity, dimensional stability during drying, a high binder effect, and a molded product with high strength. As a result of extensive research aimed at providing a composition, we found that 100 parts by weight of an inorganic pigment and an average degree of polymerization of 30
From 2000. 0.5 to 100 parts by weight of a partially saponified polyvinyl acetate resin with a degree of saponification of 5 to 60 mol%, and 1 part by weight of water.
It was discovered that an inorganic pigment dispersion composition comprising 0 to 400 parts by weight is most suitable for this purpose, and the present invention was completed.

When the composition consisting of the above components is stirred at room temperature, the partially saponified polyvinyl acetate resin absorbs water as it is stirred, swells and softens, and is ground as it comes into contact with pigment particles, enveloping the pigment surface.

The final result is a good protective colloid state. Therefore, the composition of the present invention has good uniform dispersibility of pigment.

It is an inorganic pigment dispersion composition with excellent stability, relatively low viscosity, high thixotropy even at high concentrations, and rich fluidity.Although the binder or dispersant is insoluble in water, it dries. In order to exhibit a large binder effect, the composition of the present invention exhibits remarkable effects such as good moldability, good film-forming ability, and extremely fast drying speed.

The partially saponified polyvinyl acetate resin used as a binder or dispersant in the present invention has an average degree of polymerization of 3.
0 to 2000. The degree of saponification is 5 to 60 mol%, the average degree of polymerization is 50 to 1ooo, and the degree of saponification is 5 to 5.
Optimal is 0 mol%. If the average degree of polymerization is less than 30, the molecular chain is too short and it becomes difficult to wrap the surface of the 5#I material uniformly, resulting in poor uniform dispersion and weak binder strength, making it impossible to obtain molded products with high strength. . On the other hand, if the average degree of polymerization exceeds 2000, the degree of softening will be too low even when water is absorbed, making it impossible to cover the pigment surface uniformly, resulting in poor uniform dispersibility. Furthermore, if the degree of saponification is less than 5 mol%, there are too few hydroxyl groups, so even if the pigment surface is wrapped, the bonding force is weak and unstable.

Because it easily separates from the pigment, it is difficult to form a stable protective colloid, resulting in poor uniform dispersibility. On the other hand, if the degree of saponification exceeds 60 mol%, the partially saponified polyvinyl acetate resin becomes water-soluble and the viscosity increases, making it difficult to form a highly concentrated dispersion. As the partially saponified polyvinyl acetate resin used in the present invention, a partially saponified modified polyvinyl acetate resin can also be used. Preferably used modified products include carboxyl-modified products, amide-modified products, sulfone-based products, alkyl ether-modified products, saturated branched fatty acid ester-modified products, and silicon-containing group-modified products.

What is the amount of partially saponified polyvinyl acetate resin used?

70.5 to 10 per 100 parts by weight of free 1lIII material
0 parts by weight 1 preferably 0.5 to 50 parts by weight. If the amount of the partially saponified polyvinyl acetate resin is less than 0.5 parts by weight, the binder will lack binding power and it will be difficult to form a uniform and stable protective colloid, while if it exceeds 100 parts by weight, the particles once dispersed will fuse together. It becomes sticky-like.

Examples of inorganic pigments used in the present invention include kaolinite sericite and pyroferrite.

Clays such as talc and bentonite, and coal powder.

Examples include ceramic raw materials such as graphite, alumina, zirconia, titanium oxide, silicon oxide, silicon carbide, and silicon monothioside.

The amount of water used is from 1° to 400 parts by weight, preferably from 2° to 2001 parts by weight, per 100 parts by weight of the inorganic pigment. If it is less than 10 parts by weight, almost all of the water added to the inorganic pigment will be absorbed, making it difficult to achieve a uniform dispersion state.On the other hand, if it exceeds 400 parts by weight, some of the dispersed pigment will precipitate, resulting in poor dispersion stability. It lacks.

The composition of the present invention optionally contains glycerin.

Plasticizers such as ethylene glycol and sorbitol.

Nonionic, anionic, cationic or amphoteric surfactants, peptizers such as sodium polyphosphate, polycarboxylic acids and their soda salts may be used in combination.

When the composition of the present invention is applied to a piece of paper, etc., it dries very quickly, forming a strong film on the surface of the object being coated, and when used as an adhesive, the went tank is large and the initial adhesion is poor. It has the advantage of being excellent. Also, when creating a molded product by pouring it into a mold, it dries very quickly.
There is almost no dimensional change and no cracks. It has the advantage of producing molded products with high strength. These features are thought to be due to the good water resistance due to the composition being in a protective colloid state, the reduction in the amount of evaporated water due to the high concentration, and the strong binding power of partially saponified polyvinyl acetate resin to non-III materials. be done.

The present invention will be explained in more detail with reference to five examples below.

Note that "parts" in one example mean "parts by weight."

Example 1 Kaolinite clay 100 parts 9 Degree of polymerization 280. When 30 parts of partially saponified polyvinyl acetate resin with saponification degree of 35 mol% and 50 parts of water were mixed and stirred at room temperature for 1 hour, the concentration was 72% and the viscosity measured with a BH type rotational viscometer was 2 Orpm. 3500cps at 2800 at 2 rpm
An aqueous dispersion of clay of 0 cps was obtained. The stability of this dispersion was very good, and no syneresis due to precipitation or agglomeration of pigment particles was observed even after it was left at room temperature for 1 hour. It also has good fluidity.

No problems occurred when coating the paper surface or pouring into the mold.

Examples 2 to 10 Dispersions were prepared in the same manner as in Example 1 using various inorganic pigments and partially saponified polyvinyl acetate resins shown in Table 1. The results are shown in Table 1. Here, dispersion stability is determined by observing the state change when the prepared dispersion liquid is left at room temperature for one week, and fluidity is determined by observing the state change when the dispersion prepared in 1 is left at room temperature for one week. The surface condition was observed when .5an+ was applied, and the evaluation criteria were as follows.

Dispersion stability O: No precipitates or aggregates were observed.

Δ: A slight amount of precipitate or agglomerate is observed, but it easily returns to its original state when stirred again.

×: A large amount of precipitates or aggregates were present, and a completely transparent layer appeared on the surface of the 3-dispersion. It is not easy to return to the original state by stirring again.

Liquidity ○: A smooth and very uniform coating layer is formed on the back surface.

Δ: Although the surface is smooth, there are striped patterns and the uniformity of the coating layer is slightly inferior.

×: Fading occurs during coating, and a uniform coating layer cannot be obtained.

Comparative Example 1 Degree of polymerization: 280. Polymerization degree of 600. A dispersion was prepared in the same manner as in Example 1 except that polyvinyl alcohol with a degree of saponification of 88 mol% was used, but the viscosity increased rapidly after 10 minutes of stirring and it was not possible to form a uniform dispersion. Ta. The viscosity at this time was measured and was over 2,000,000 cps, indicating very poor fluidity.

Comparative Example 2 Degree of polymerization: 280. A dispersion was prepared in the same manner as in Example 1 except that sorbitol was used instead of the partially saponified polyvinyl acetate resin with a degree of saponification of 35 mol%.The viscosity at 30°C was 2800 cps at 20 rpm, A dispersion of +5000 cps was obtained, but when left as it was at room temperature, precipitation occurred after one day and the pigment dispersion stability was very poor.

Comparative Example 3 Degree of polymerization: 280. In place of the saponified product of the polyvinyl resin portion with a saponification degree of 35 mol%, a polymerization degree of 25. Saponification degree 35 mol%
A dispersion liquid was prepared in the same manner as in Example 1 except that the partially saponified polyvinyl acetate resin was used.

The results are shown in Table 1.

Comparative Example 4 Degree of polymerization: 280. Polyvinyl acetate resin partially saponified product with a saponification degree of 35 mol % was replaced with a polymerization degree of 280. A dispersion liquid was prepared in the same manner as in Example 1 except that a partially saponified polyvinyl acetate resin having a degree of saponification of 3 mol % was used. The results are shown in Table 1.

Comparative Example 5 Degree of polymerization: 280. Polyvinyl acetate resin partially saponified product with a saponification degree of 35 mol % was replaced with a polymerization degree of 280. A dispersion liquid was prepared in the same manner as in Example 1 except that a partially saponified polyvinyl acetate resin having a saponification degree of 70 mol% was used. The results are shown in Table 1.

Example 11 Zirconia 100 parts 1 Polymerization degree 280. When 5 parts of a partially saponified polyvinyl acetate resin with a degree of saponification of 30 mol% and 30 parts of water were mixed and stirred at room temperature for 1 hour, the viscosity at 30°C was 14,000 cps at 2 Orpm and 98 at 2 rpm.
An aqueous zirconia dispersion with a concentration of 78% by weight and excellent dispersion stability and high fluidity of 700 cps was obtained. When this dispersion was poured into a plaster mold to make a molded product, a highly strong molded product with almost no dimensional change was obtained.

Agent Yuzo Kodama

Claims (1)

[Claims] ti) 100 parts by weight of an inorganic pigment and an average degree of polymerization of 30 to 2
000, and 0.5 to 100 parts by weight of a partially saponified polyvinyl acetate resin having a degree of saponification of 5 to 60 mol%. An inorganic pigment dispersion composition comprising 10 to 400 parts by weight of water.