JPH0925429A - Titanium dioxide pigment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a titanium dioxide pigment excellent in storage stability. SOLUTION: This titanium dioxide pigment comprises hydrous silicon oxide and hydrous aluminum hydroxide in respective amounts of 2-15wt.% and 1-10wt.% expressed in terms of SiO2 and Al2 O3 present on the surface of a rutile or an anatase type titanium dioxide having 0.15-0.3μm average particle diameter and further 0.05-5wt.% organometallic compound present thereon.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a titanium dioxide pigment used in paints, inks and plastics. In particular, it is suitably used for paints, inks, etc., which are non-aqueous and are required to have high hiding property, and also useful for plastics.

[0002]

2. Description of the Related Art In fields such as non-aqueous architectural paints, printing inks, etc., which require high hiding power with high pigment concentration and, in some cases, matte effect, a large amount of silicon oxide hydroxide and aluminum hydroxide used for aqueous emulsion paint is used. Surface-treated titanium dioxide is often used. Examples of techniques relating to these include Japanese Patent Application No. 44-25660 and Japanese Patent Application No. 50-62579.

[0003]

The paints and printing inks using the titanium dioxide pigments manufactured by the conventional techniques can obtain high hiding power and a moderate matting effect, but when the paints are stored for a long time. Redispersion was often difficult due to the formation of a hard precipitate. It is an object of the present invention to provide a titanium dioxide pigment having a high hiding power, an excellent matting effect and an excellent storage stability when used in a paint.

[0004]

According to the present invention, hydrous silicon oxide and aluminum hydrous oxide are added to the surface of a rutile or anatase type having an average particle diameter of 0.15 to 0.3 μm by SiO _2.
And _{2 to} 15% by weight as Al ₂ O ₃ and 1-1, respectively.
0% by weight of the organic silicon compound and 0.05
.About.5% by weight of titanium dioxide pigment. Here, the average particle size is the same as the particle size of general titanium dioxide used as a white pigment, and in the case of the rutile type, it is 0.2 to 0.
3 μm, and 0.15 to 0.2 μm in the case of anatase type. As the crystal form of titanium dioxide used as a substrate, the rutile type with a high refractive index is generally used when high hiding power is required, but the anatase type is used when a pale color tone due to light scattering on the short wavelength side is required. You can also

In order to allow the hydrous silicon oxide and the hydrous aluminum oxide to exist on the surface of the titanium dioxide serving as the base, a 100 to 500 g / l slurry of the titanium dioxide serving as the base is maintained at 30 to 100 ° C. and a predetermined amount of silicon compound is added. Water solution while maintaining a constant pH, or by adding an aqueous solution of a silicon compound and then neutralizing it, or adding an acid necessary for neutralization in advance, and then adding an aqueous solution of the silicon compound to obtain a water content of silicon. After the oxide is precipitated, it is aged for 30 to 90 minutes if necessary. Then, an aqueous solution of the aluminum compound is gradually added while maintaining a constant pH, or after the aqueous solution of the aluminum compound is added, neutralization or an acid necessary for neutralization is added, and then the aqueous solution of the aluminum compound is added to obtain the water content of aluminum. The oxide is precipitated and, if necessary, aged for 30 to 90 minutes, filtered, washed with water and dried. The water-soluble silicon compound used is generally sodium silicate, but potassium silicate may be used. Examples of the water-soluble aluminum compound include aluminum sulfate, aluminum chloride, aluminum nitrate, sodium aluminate and the like. Examples of the acid used for neutralization include sulfuric acid, hydrochloric acid and nitric acid, and examples of the alkali include sodium hydroxide, potassium hydroxide and ammonium hydroxide.

The amount of silicon compound added is ₂ as SiO 2.
-15% by weight, preferably 5-10% by weight. When it is 2% by weight or less, the hiding power is low and the matting effect is also low.
If it is 15% by weight or more, the oil absorption amount becomes too high. The amount of the aluminum compound added is 1 to 10% by weight as Al ₂ O _3.
And preferably 2 to 5% by weight. If it is less than 1% by weight, the hiding power is low, and if it is more than 10% by weight, the oil absorption becomes too high.

The organometallic compounds are organosilicon compounds, organoaluminum compounds, organotitanium compounds and organozirconium compounds. Taking an organosilicon compound as an example of a method for allowing an organometallic compound to exist, the hydrous oxide of silicon and the hydrous oxide of aluminum are precipitated, and a predetermined amount of the organosilicon compound is mixed in the cake after filtration and washing with water, followed by drying and It may be crushed, or may be mixed with an organic silicon compound in a dry cake and then crushed. Alternatively, the dried cake may be crushed and then mixed with an organosilicon compound.

The organosilicon compound used is not particularly limited, and dimethylpolysiloxane (KF9 manufactured by Shin-Etsu Silicone Co., Ltd.)
6, Toshiba Silicone TSF451), methylhydrogenpolysiloxane (Shin-Etsu Silicone KF99, Toshiba Silicone TSF484), methylphenylpholysiloxane (Shin-Etsu Silicone KF54, Toshiba Silicone TSF431), diphenyldimethoxysilane (Shin-Etsu Silicone KBM202, Toshiba Silicone TSL8
172), γ-glycidoxypropyltrimethoxysilane (KBM403 from Shin-Etsu Silicone, TSL8350 from Toshiba Silicone), γ-methacryloxypropylmethoxysilane (KBM503 from Shin-Etsu Silicone, TSL8370 from Toshiba Silicone), γ-aminopropyltrimethoxysilane. (KBM903 made by Shin-Etsu Silicone, TSL8331 made by Toshiba Silicone), vinyltriethoxysilane (KBE1003 made by Shin-Etsu Silicone, TSL8311 made by Toshiba Silicone) and the like can be mentioned. The addition amount of the organosilicon compound is 0.05 to 5% by weight, preferably 0.
1 to 3% by weight. If it is 0.05% or less, the effect of improving the storage stability is small, and even if it is added in an amount of 5% by weight or more, no further improvement is observed.

[0009] Other organic metal compounds are exemplified, but the organoaluminum compound is not particularly limited. For example, acetoalkoxyaluminum diisopropylate (AL-M manufactured by Ajinomoto Co.), aluminum bisethylacetoacetate monoacetylacetonate ( Examples include aluminum chelate D) manufactured by Kawaken Fine Chemical Co., Ltd.

The organic titanium compound is not particularly limited, and examples thereof include tetraoctyl bis (ditridecyl phosphite) titanate (KR46B manufactured by Ajinomoto Co.), bis (dioctylpyrophosphate) oxyacetate titanate (KR138S manufactured by Ajinomoto Co.), Isopropyl tricumyl phenyl titanate (Ajinomoto Co., KR3
4S) and the like.

The organic zirconium compound is not particularly limited, and examples thereof include zirconium acetylacetonate bisethylacetoacetate (ZC-manufactured by Sugimoto Yushi-Seiyaku Co., Ltd.).
570), zirconium bisacetylacetonate (ZC-550 manufactured by Sugimoto Yushi-Seiyaku Co., Ltd.) and the like.

The titanium dioxide pigment produced by the above method has a high hiding power and an excellent matting effect in non-aqueous paint pigments having a high pigment concentration and stationery correction liquid, and the precipitate formed by storage of the paint ink is soft. It exhibits excellent redispersibility.

[0013]

[Examples] Specific examples will be described below. Example: An aqueous slurry of rutile type titanium dioxide substrate having an average particle size of 0.25 μm (TiO ₂ concentration of 350 g / l) was heated to 70 ° C. with stirring, and then a sodium silicate aqueous solution was added while maintaining the pH at 4 with dilute sulfuric acid. SiO ₂ and based on the weight of the base body
8% to precipitate a hydrous oxide of silicon and then aged for 30 minutes. Subsequently the aqueous aluminum sulfate solution while maintaining the temperature at 70 ° C., based on the weight of said substrate Al ₂
After 3% of O ₃ was added, the pH was adjusted to 7.5 with an aqueous sodium hydroxide solution to precipitate aluminum hydrous oxide, and then aged for 1 hour. Then, the slurry is filtered and washed with water,
After drying, 1% by weight of methylhydrogenpolysiloxane (manufactured by Toshiba Silicone, TSF484) was added and mixed with the dried product and pulverized to obtain a titanium dioxide pigment of the present invention (Pigment A).

Comparative Example 1 In the same manner as in Example 1, a hydrous oxide of silicon or aluminum was precipitated on a titanium dioxide substrate, followed by filtration, washing with water, drying and pulverization to obtain titanium dioxide which was not treated with an organosilicon compound ( Pigment B).

Comparative Example 2 An aqueous slurry of rutile type titanium dioxide substrate having an average particle diameter of 0.25 μm (TiO ₂ concentration of 350 g / l) was heated to 70 ° C. with stirring, and then an aqueous sodium silicate solution was used on a weight basis of the substrate. Then, 1% of SiO ₂ was added, and the mixture was neutralized to pH 7 with dilute sulfuric acid to precipitate silicon hydrous oxide.
Next, while maintaining the pH at 7 with dilute sulfuric acid, an aqueous solution of sodium aluminate was gradually added to the substrate as Al ₂ O _{3 in an amount} of 2% on a weight basis to precipitate a hydrous oxide of aluminum and aged for 60 minutes. Subsequently, the slurry is filtered and washed with water,
After drying, 0.7% by weight of dimethylpolysiloxane (KF96, manufactured by Shin-Etsu Silicone) was added to the dried product and mixed, and pulverized to obtain a titanium dioxide pigment (Pigment C).

Evaluation method 70 g of titanium dioxide pigments A to C were mixed in 88 g of acrylic lacquer varnish (solid content 26.5%) (pigment / resin solid content = 3/1), and the particles were 10 μm with a paint shaker.
A paint was prepared by dispersing until the following. This paint 3
The glass plate was coated with a mils applicator, left to dry overnight, and then the 60 ° -60 ° specular gloss was measured with a gloss meter to determine the degree of matting. Also, the hiding power was evaluated by measuring the hunter system L value (brightness) with a color meter. Regarding the storage stability of the paint, after diluting the prepared paint with 10% lacquer thinner based on the weight, 4
It was stored for 7 days in a 0 ° C. thermostat, and the hardness of the precipitate and the difficulty of returning the precipitate to the original state by stirring and mixing were judged. The results are shown in Table 1.

[0017]

[Table 1]

[0018]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a titanium dioxide pigment having a high pigment concentration in the coating ink field, which is excellent in redispersibility of a precipitate after storage and has a high hiding power and an excellent matting effect. Became.

Claims (1)

[Claims] 1. Hydrous silicon oxide and aluminum hydroxide as SiO ₂ and Al ₂ O _{3 on} the surface of rutile or anatase type titanium dioxide having an average particle diameter of 0.15 to 0.3 μm, respectively, in an amount of 2 to 15% by weight, 1 to A titanium dioxide pigment in which 10% by weight is present and 0.05 to 5% by weight of an organometallic compound is further present.