JPH0525912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to ultramarine blue surface treated with a silane coupling agent.

Prior Art Ultramarine pigment is a non-polluting inorganic pigment with a unique clear hue, and has a wide range of uses as a blue inorganic pigment with excellent light resistance and heat resistance, including synthetic resins, paints, printing inks, cement, and detergents.

However, ordinary ultramarine pigments have insufficient acid resistance and have the disadvantage of decomposing and fading even in weak acidity of about PH5 at room temperature.Also, when coloring plastics that become acidic over time (for example, vinyl chloride resin), it is difficult to color them over time. It fades and turns white.

Although it is said to have excellent alkali resistance, it is weak against cement alkalis and may cause a substitution reaction with Ca ions, causing fading and whitening, so its uses tend to be limited.

Therefore, at present, improving the coloring power of ultramarine pigments and improving acid resistance and cement alkali resistance are important issues, but amorphous silica deposition coating technology is effective for improving the latter two properties. be. The technique of depositing amorphous silica on the surface of inorganic pigment particles to improve various resistances originated in US Pat. No. 2,885,366. This patent relies exclusively on the reaction of an aqueous sodium silicate solution with a mineral acid to deposit amorphous silica onto pigment particles. However, when this is applied to ultramarine pigments, as mentioned above, the acid resistance is very poor, and by the time the pigment is coated with amorphous silica, it is attacked by mineral acids and fades and turns white. Therefore, as an improved technique, a combination of a weakly acidic agent having a hardening effect and an aqueous sodium silicate solution can be considered. For example, the application of carbonic acid (CO ₂ aqueous solution) in US Pat. No. 3,437,502 and the application of water-soluble organic acids in Japanese Patent Publication No. 55-34184 (Toho Pigment, Nihon Kagaku) are known.

According to the above-mentioned improved technique, when amorphous silica is deposited and coated on the surface of ultramarine blue pigment particles, the purpose can be achieved without damaging the ultramarine pigment itself.

The degree of acid resistance of the improved ultramarine pigment obtained in this way was evaluated by _the acid resistance test shown in the examples _.
After 10 hours of immersion at 25℃, the color difference (ΔE) was 1.34−
3.38; 14% silica coating shows an improvement of color difference (ΔE) of 1.42. In this case, CO ₂ gas was used as the weak acidic agent. Moreover, the variation in color difference at the same coverage percentage is based on the variation in the particle size of the applied ultramarine particles. Untreated ultramarine pigments show a color change of more than 10 in a similar test.

Problems to be Solved by the Invention As mentioned above, ultramarine blue obtained by depositing and coating amorphous silica on the surface of ultramarine pigment particles has excellent acid resistance, but because its surface is hydrophilic, it is susceptible to organic matter. For example, when blended with plastics, there may be problems with their compatibility, and
When mixed with cement, etc., it tends to cause a substitution reaction with Ca in the cement, causing discoloration. In some cases, even better acid resistance may be required.

The present invention aims to solve the above problems.

Means for Solving the Problem The present inventors have discovered that the above problem can be solved by further treating the ultramarine surface coated with amorphous silica with a silane coupling agent.

That is, the present invention provides ultramarine in which the surface of an amorphous silica-coated ultramarine is treated with a silane coupling agent that has a hydrolyzable group bonded to a silicon atom and an unsaturated group or an epoxy group, but does not have an amino group. Regarding.

The amorphous silica-coated ultramarine used in the present invention may be produced by a conventionally known method. For example, ultramarine blue is dispersed in an aqueous alkali silicate solution, and a suitable acid such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid, citric acid, etc. is gradually added to the solution, and amorphous silica is deposited and coated on the surface of ultramarine particles. 55-34184), a method using acidic gas as the acid (Japanese Patent Publication No. 59-15154)
(No. 3) may be used as appropriate.

The coating of ultramarine with amorphous silica is different from ultramarine.
Silica is preferably 5% by weight or more, and the particle size of ultramarine is as uniform as possible, preferably ± with respect to the average particle size.
The range is preferably 5 μm, more preferably ±1 μm.

As the silane coupling agent, commercially available silane coupling agents may be used _as appropriate, but the silane coupling agent has the general formula: ] It is indicated by.

Specific examples of X include polymerizable unsaturated groups such as vinyl groups and (meth)acrylic groups, and epoxy groups. As those having unsaturated groups,
For example, KBE-1003, KBM-503 (Shin-Etsu Chemical Co., Ltd.)
(manufactured by Toray Silicone Co., Ltd.), SH-6030 (manufactured by Toray Silicone Co., Ltd.), A-
174 (manufactured by UCC) etc. are exemplified. As a silane coupling agent with an epoxy group, KBM-
403 (manufactured by Shin-Etsu Chemical Co., Ltd.), SH-6040 (manufactured by Toray Silicone Co., Ltd.), A-187 (manufactured by UCC), etc.

Examples of Y include chloro, an alkoxy group (particularly a methoxy group and an ethoxy group), and the like. Preferred is an alkoxy group. When Y is halogen, a dehalogenating agent is required during treatment.

Among the silane coupling agents that can be used in the present invention, particularly preferred compounds include vinyltriethoxysilane, vinyltricellosolve ester silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc. be.

The silane coupling agent reacts with the silanol groups of the amorphous silane coupling agent formed on the surface of the ultramarine particles as shown below, filling the minute cracks that exist between the deposited silica films and preventing the ultramarine from coming into contact with acids or cement alkalis. It is understood that the formed reactive group (X) improves the affinity with organic substances.

Treatment of amorphous silica-coated ultramarine with a silane coupling agent: When using a silane coupling agent in which Y is an alkoxy group, the amorphous silica-coated ultramarine is dispersed in a suitable solvent, such as water, and the silane coupling agent is added to the amorphous silica-coated ultramarine. Alternatively, the amorphous silica-coated ultramarine may be added to the silane coupling agent solution. The reaction is preferably carried out in an aqueous medium, with a pH of 7 to 10, especially 8 to 10,
Although it can be carried out at room temperature, it is preferably 50°C.
It is best to do this at ~70°C. A processing time of 20 to 30 minutes is sufficient. When using a silane coupling agent in which Y is halogen, an equivalent amount of an aqueous alkaline solution may be used.

In order to fill the cracks in the amorphous silica film, it is desirable to completely hydrolyze the silane coupling agent and to perform dehydration condensation with the silanol groups of the amorphous silica as completely as possible. To this end, it is preferable to raise the temperature of the reaction medium, for example to 90°C or higher, at the end of the reaction, or to dry the treated ultramarine at 90°C or higher.

The amount of silane coupling agent used is 0.5 to 5.0
%, preferably 1.0-2.0%.

Effects of the invention When ultramarine is coated with amorphous silica and then treated with a silane coupling agent, its acid resistance is significantly improved compared to coating only with amorphous silica, and fading due to cement alkali is improved. This makes it possible to incorporate it into cement. Furthermore, the compatibility with organic materials such as plastics is significantly improved.

Example 1 A water-washed press cake (60 to 65% product) of an amorphous silica-coated ultramarine pigment (12% silica coating, average particle size of about 2.5 μm, acid resistance color difference 1.34) was used as a dry product.
Take an amount equivalent to 100g and add water to make a 10% slurry.

Add 2 silane coupling agents (Toray SH-6040; glycidyl silane) to this slurry at room temperature while stirring.
% aqueous solution (2% based on the silica-coated ultramarine) was added dropwise to the surface, and the surface was treated for 30 minutes at room temperature, followed by filtration, washing with water, and drying (heat treatment) at 105°C for 5 hours.

The acid resistance color difference of the obtained ultramarine blue pigment treated with a silane coupling agent was 0.77.

Example 2 A water-washed press cake (60-65% product) of an amorphous silica-coated ultramarine pigment (12% silica coating, average particle size of about 1.5 μm, acid resistance color difference 3.38) was used as a dry product.
Take an amount equivalent to 100g and add water to make a 10% slurry. ) In the same manner as in Example 1, a treatment (for pigments) with a 2% aqueous solution of silane coupling agent Toray SH-6030 (methacrylic silane) was carried out.

The acid resistance color difference of the obtained ultramarine blue pigment treated with a silane coupling agent was 1.67.

Example 3 A washed press cake (60-65% product) of an amorphous silica-coated ultramarine pigment (14% silica coating, average particle size of about 2 μm, acid resistance color difference 1.42) was used as a dry product.
Take an amount equivalent to 100g and add water to make a 10% slurry.

A 2% aqueous solution of silane coupling agent Toray SH-6040 (glycidyl silane) was prepared in the same manner as in Example 1.
Drop 50g (1% of silica-coated ultramarine),
Surface treatment was performed (addition at room temperature and when heated). The acid resistance color difference of the obtained ultramarine treated with a silane coupling agent was 0.45 and 0.22, respectively.

The acid resistance test method adopted in the above examples is as follows.

(1) Preparation of sample Treated (or untreated) ultramarine pigment: 1 part titanium oxide, 1 part PVC clear (N.V 40%). Mix a mill base with 5 parts and use a ball mill to obtain a paint with a dispersed particle size of 10 μm or less. It was applied to a thickness of 7 mils (175 μm) using an applicator on a corrosion-resistant aluminum plate and heated at 105℃.
Dry for 60 minutes to obtain a test plate.

(2) Acid resistance test The test coated plate obtained as above was treated with 5% H ₂ SO ₄
After immersing in an aqueous solution at 25°C for 10 hours, it is taken out, washed with water, and then dried.

(3) Judgment Using a photoelectric color difference meter, determine the L, a, and b values before dipping and the L', a', and b' values after dipping. The color difference (ΔE) is determined from the difference in the above measured values (ΔL, Δa, Δb) and is used as the acid resistance color difference.

Claims (1)

[Claims] 1. Ultramarine blue in which the surface of amorphous silica-coated ultramarine is treated with a silane coupling agent that has a hydrolyzable group bonded to a silicon atom and an unsaturated group or an epoxy group, but does not have an amino group.