Preparation method of colored titanium dioxide and colored titanium dioxide

Abstract

The invention discloses a preparation method of colored titanium dioxide and the colored titanium dioxide, and relates to the technical field of titanium dioxide pigments. The surface of titanium dioxide is coated with silicon dioxide, so that free radicals generated by titanium dioxide can be shielded, and degradation of pigments is avoided; the sodium aluminate reacts with the pigment to enable aluminum hydroxide generated by the sodium aluminate to be adsorbed with the pigment to form a color lake, so that anchoring of chromaticity on the colored titanium dioxide is improved, and meanwhile, the stability of the pigment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide pigments, in particular to a preparation method of colored titanium dioxide and the colored titanium dioxide. Background Art

[0002] Titanium dioxide (TiO2), chemically formulated as TiO2, is a white inorganic compound widely used in pigments, coatings, plastics, cosmetics, and food additives. By coloring the surface of titanium dioxide, white TiO2 can be given different colors, expanding its application range. For example, black titanium dioxide is used in photothermal conversion, lithium-ion batteries, and photocatalytic degradation of pollutants. Yellow and red titanium dioxide is used in ceramic glazes and high-temperature-resistant coatings. Blue titanium dioxide is used in decorative coatings and electronic display materials.

[0003] Currently, colored titanium dioxide is mainly prepared by doping or modification, but there is a common problem of low color fastness.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of colored titanium dioxide and colored titanium dioxide, aiming to provide a new colored titanium dioxide product that can significantly improve the color fastness of the colored titanium dioxide.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a method for preparing colored titanium dioxide, comprising:

[0008] Providing titanium dioxide pigments with a surface coated with silicon dioxide;

[0009] Under the condition of pH value of 6.5-7.5, sodium aluminate is reacted with pigment to coat the surface of titanium dioxide pigment with organic pigment.

[0010] In an optional embodiment, the preparation process of titanium dioxide pigment coated with silicon dioxide includes: heating the titanium dioxide slurry to 70°C-90°C, adjusting the pH value to 9.5-10.5, and reacting with sodium silicate solution while maintaining the pH value at 9.5-10.5.

[0011] In an optional embodiment, the mass ratio of titanium dioxide in the titanium dioxide slurry to the mass ratio of sodium silicate in the sodium silicate solution is (15-25):1;

[0012] And / or, the concentration of titanium dioxide in the titanium dioxide slurry is 300 g / L-400 g / L, and the mass fraction of the sodium silicate solution is 20%-35%.

[0013] In an optional embodiment, the sodium silicate solution is added at a rate of 0.5 mL / min-5 mL / min;

[0014] and / or, adding hydrochloric acid solution during the reaction to maintain the pH value of the system at 9.5-10.5;

[0015] And / or, the D50 of the titanium dioxide particles in the titanium dioxide slurry is 0.20 μm to 0.35 μm.

[0016] In an optional embodiment, the process of coating the surface of the titanium dioxide pigment with an organic pigment includes: after the sodium silicate solution is added, adjusting the pH value to 6.5-7.5, adding the pigment, sodium aluminate and inorganic acid to react, and controlling the reaction temperature to 70°C-90°C.

[0017] In an optional embodiment, during the process of adding the pigment, sodium aluminate and inorganic acid to react, a mixed solution formed by the pigment and the inorganic acid and a sodium aluminate solution are added simultaneously;

[0018] Alternatively, a mixed solution of pigment and sodium aluminate and an inorganic acid solution are added simultaneously.

[0019] In an optional embodiment, the mass ratio of the added pigment to the sodium aluminate is (0.05-0.30):1, and the mass ratio of the titanium dioxide in the titanium dioxide slurry to the added sodium aluminate is (55-70):1.

[0020] In an optional embodiment, the pH value is adjusted to 6.5-7.5 by adjusting the amount of added inorganic acid;

[0021] And / or, the inorganic acid is dilute hydrochloric acid with a mass fraction of 3%-5%.

[0022] In an optional embodiment, after the pigment and sodium aluminate are added, the temperature is maintained for 0.2h-1.0h, and then the solid-liquid separation is performed, and the obtained solid material is washed and dried;

[0023] and / or, adding a mixed solution of pigment and sodium aluminate and an inorganic acid solution simultaneously, controlling the addition rate of the mixed solution to be 0.5 mL / min-2.0 mL / min;

[0024] And / or, the color of the pigment is selected from at least one of yellow, red and blue.

[0025] In a second aspect, the present invention provides colored titanium dioxide prepared by the preparation method of any one of the aforementioned embodiments.

[0026] The present invention has the following beneficial effects: coating the surface of titanium dioxide with silicon dioxide can shield the free radicals generated by titanium dioxide and avoid the degradation of the pigment; utilizing the reaction between sodium aluminate and pigment to make the aluminum hydroxide generated by sodium aluminate adsorbed with the pigment to form a lake, thereby increasing the anchoring of the color on the colored titanium dioxide and improving the stability of the pigment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a picture of Example 1 showing the dispersion of colored titanium dioxide in a plastic product;

[0029] Figure 2 This is a colored electron microscope image of titanium dioxide in Example 1. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0031] The present invention provides a method for preparing colored titanium dioxide, comprising the following steps:

[0032] S1, coated silica

[0033] The surface of titanium dioxide particles is coated with silicon dioxide, which can effectively shield the free radicals generated by titanium dioxide and prevent the degradation of organic pigments.

[0034] The method for coating silica is not limited. In some embodiments, the preparation process of a titanium dioxide pigment coated with silica includes heating a titanium dioxide slurry to 70°C-90°C, adjusting the pH to 9.5-10.5, adding a sodium silicate solution for reaction, and simultaneously adding a hydrochloric acid solution to maintain the pH at 9.5-10.5. The sodium silicate solution and the hydrochloric acid react to produce silica and sodium chloride. The silica is coated on the surface of the titanium dioxide to shield the free radicals generated by the titanium dioxide after exposure to light.

[0035] Specifically, the titanium oxide slurry can be a commercially available material, the reaction temperature can be controlled to be 70°C, 75°C, 80°C, 85°C, 90°C, etc., and the pH value of the slurry after adjusting the pH value can be 9.5, 9.8, 10.0, 10.3, 10.5, etc.

[0036] Furthermore, the mass ratio of titanium dioxide in the titanium dioxide slurry to the mass ratio of sodium silicate in the sodium silicate solution is (15-25):1, and the mass ratio of titanium dioxide to sodium silicate can be controlled to be 15:1, 18:1, 20:1, 23:1, 25:1, etc. The concentration of titanium dioxide in the titanium dioxide slurry is 300g / L-400g / L, such as 300g / L, 330g / L, 350g / L, 380g / L, 400g / L, etc. The D50 of the titanium dioxide particles in the titanium dioxide slurry is 0.20μm-0.35μm, such as 0.20μm, 0.25μm, 0.30μm, 0.35μm, etc. The mass fraction of the sodium silicate solution is 20%-35%, such as 20%, 23%, 25%, 28%, 30%, 33%, 35%, etc. By adjusting the amount of titanium dioxide and sodium silicate and the concentration of the solution, the generated silicon dioxide can be evenly coated on the surface of the titanium dioxide particles, and the thickness of the silicon dioxide protective layer can be more appropriate.

[0037] Furthermore, the sodium silicate solution is added at a rate of 0.5 mL / min-5 mL / min, such as 0.5 mL / min, 1.0 mL / min, 2.0 mL / min, 3.0 mL / min, 4.0 mL / min, 5.0 mL / min, etc. During the reaction, hydrochloric acid solution is added to maintain the pH value of the system at 9.5-10.5. The mass fraction of the hydrochloric acid solution is not limited, such as 10%-20%.

[0038] S2, coated pigment

[0039] Sodium aluminate reacts with pigments at a pH of 6.5-7.5 to coat the titanium dioxide pigment with organic pigments. At a pH of 6.5-7.5, sodium aluminate efficiently generates amorphous Al(OH)3, which adsorbs the pigments through electrostatic or hydrogen bonding, forming a lake. This enhances the anchoring of color and improves the stability of the pigments. Specifically, the reaction pH can be 6.5, 6.8, 7.0, 7.3, 7.5, and so on.

[0040] In some embodiments, the process of coating the surface of the titanium dioxide pigment with an organic pigment includes: after the sodium silicate solution is added, the pH value is adjusted to 6.5-7.5 with dilute hydrochloric acid, the pigment, sodium aluminate and inorganic acid are added to react, and the reaction temperature is controlled to be 70°C-90°C (such as 70°C, 75°C, 80°C, 85°C, 90°C, etc.), after the pigment and sodium aluminate are added, the reaction is kept warm for 0.2h-1.0h (such as 0.2h, 0.5h, 0.8h, 1.0h, etc.) to complete the reaction, followed by solid-liquid separation, and the obtained solid material is washed and dried. The method of solid-liquid separation is not limited, such as filtering. The method of drying is not limited, such as drying. After drying, it can be further crushed to obtain a colored titanium dioxide pigment.

[0041] In some embodiments, there are two methods for adding pigment, sodium aluminate, and inorganic acid to the reaction: (1) adding the mixed solution of pigment and inorganic acid and the sodium aluminate solution simultaneously; (2) adding the mixed solution of pigment and sodium aluminate and the inorganic acid solution simultaneously. Both methods are feasible and can uniformly coat the organic pigment.

[0042] In some embodiments, the mass ratio of the added pigment to the sodium aluminate is (0.05-0.30):1, such as 0.05:1, 0.10:1, 0.15:1, 0.20:1, 0.25:1, 0.30:1, etc. The mass ratio of the mass of titanium dioxide in the titanium dioxide slurry to the added sodium aluminate is (55-70):1, such as 55:1, 60:1, 65:1, 70:1, etc. By adjusting the amount of pigment and sodium aluminate, the coating amount of the organic pigment can be further adjusted, which is conducive to obtaining a colored titanium dioxide product with more anchored color and higher stability. When the mixed solution of pigment and sodium aluminate and the inorganic acid solution are added simultaneously, the addition rate of the mixed solution is controlled to be 0.5 mL / min-2.0 mL / min, such as 0.5 mL / min, 1.0 mL / min, 1.5 mL / min, 2.0 mL / min, etc.

[0043] Furthermore, the amount and type of the inorganic acid are not limited, for example, it can be 3%-5% by mass of dilute hydrochloric acid, and the pH value can be adjusted to 6.5-7.5 by adjusting the amount of the added inorganic acid.

[0044] In some embodiments, the color of the pigment is selected from at least one of yellow, red and blue, and can be a common organic pigment, which can be selected according to needs, such as lemon yellow, allure red, bright blue pigment, etc.

[0045] The embodiment of the present invention also provides a colored titanium dioxide. The preparation method provided by the embodiment of the present invention can obtain colored titanium dioxide with higher color fastness. The product not only has the high hiding power of titanium dioxide, but also has a rich hue system of titanium dioxide pigments, which broadens the application effect space.

[0046] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0047] Example 1

[0048] This embodiment provides a method for preparing colored titanium dioxide, the steps are as follows:

[0049] (1) Add 2 L of wet-ground qualified titanium dioxide slurry (titanium dioxide particles D50 = 0.2 μm-0.35 μm, TiO2 is 350 g / L) to a stirred reactor, heat to 80°C, add 10% by mass sodium hydroxide aqueous solution to adjust the pH to about 10.0 (controlled within the range of 9.5-10.5), add 100 mL of 28% by mass sodium silicate solution at a rate of 2 mL / min, and use 15% by mass hydrochloric acid to maintain the pH constant.

[0050] (2) After the sodium silicate solution in step (1) is added, the temperature is maintained at 80° C., the pH is adjusted to 6.5-7.5 with 5% dilute hydrochloric acid, and 100 mL of a mixed solution of pigment and sodium aluminate (the pigment is allura red, with a pigment mass fraction of 2.0% and a sodium aluminate mass fraction of 10%) is added at a rate of 1 mL / min. 5% dilute hydrochloric acid is added simultaneously to maintain the pH value constant. After the mixed solution is added, the mixture is kept warm for half an hour, filtered, washed, dried, and crushed to obtain a colored titanium dioxide pigment.

[0051] In this embodiment, the mass ratio of titanium dioxide in the titanium dioxide slurry to the sodium silicate in the sodium silicate solution is 20.5:1, the mass ratio of the added pigment and sodium aluminate is 0.2:1, and the mass ratio of titanium dioxide in the titanium dioxide slurry to the added sodium aluminate is 63.6:1.

[0052] Figure 1 This is a picture of Example 1 showing the dispersion of colored titanium dioxide in a plastic product. It can be seen that the titanium dioxide is evenly dispersed and the coloring effect of the plastic product is good. Figure 2 This is a colored electron microscope image of titanium dioxide in Example 1.

[0053] Example 2

[0054] The only difference from Example 1 is that the volume of the sodium silicate solution is adjusted so that the mass ratio of titanium dioxide in the titanium dioxide slurry to the mass ratio of sodium silicate in the sodium silicate solution is 15:1.

[0055] Example 3

[0056] The only difference from Example 1 is that the volume of the sodium silicate solution is adjusted so that the mass ratio of titanium dioxide in the titanium dioxide slurry to the mass ratio of sodium silicate in the sodium silicate solution is 25:1.

[0057] Example 4

[0058] The only difference from Example 1 is that the added volume of the mixed solution of pigment and sodium aluminate is adjusted so that the mass ratio of titanium dioxide in the titanium dioxide slurry to the added sodium aluminate is 55:1.

[0059] Example 5

[0060] The only difference from Example 1 is that the added volume of the mixed solution of pigment and sodium aluminate is adjusted so that the mass ratio of titanium dioxide in the titanium dioxide slurry to the added sodium aluminate is 70:1.

[0061] Example 6

[0062] The only difference from Example 1 is that the mass fraction of the pigment in the mixed solution of pigment and sodium aluminate is adjusted, the volume of the mixed solution remains unchanged, the mass fraction of sodium aluminate remains unchanged, the mass fraction of the pigment is adjusted to 0.5%, and the mass ratio of the added pigment to sodium aluminate is 0.05:1.

[0063] Example 7

[0064] The only difference from Example 1 is that the mass fraction of the pigment in the mixed solution of pigment and sodium aluminate is adjusted, the volume of the mixed solution remains unchanged, the mass fraction of sodium aluminate remains unchanged, the mass fraction of the pigment is adjusted to 3%, and the mass ratio of the added pigment to sodium aluminate is 0.3:1.

[0065] Example 8

[0066] The only difference from Example 1 is that the reaction temperature in steps (1) and (2) is controlled at 70°C.

[0067] Example 9

[0068] The only difference from Example 1 is that the reaction temperature in steps (1) and (2) is controlled at 90°C.

[0069] Comparative Example 1

[0070] This comparative example provides an existing method for coloring titanium dioxide, and the steps are as follows: titanium dioxide and lemon yellow pigment are directly blended and kneaded according to the ratio of pigment to titanium dioxide in Example 1 to obtain colored titanium dioxide.

[0071] Test Example 1

[0072] The colored titanium dioxide pigments prepared in the Examples and Comparative Examples of the present invention were used to process plastics. Using polypropylene as the base material, 3% of the total weight of the colored titanium dioxide was added. The color data obtained using an X-Rite colorimeter are shown in Table 1. The UV light irradiation test data for the plastic products processed from Example 1 and Comparative Example 1 are shown in Table 2.

[0073] Table 1 Color detection data of colored titanium dioxide after dispersion in polypropylene plastic

[0074]

[0075]

[0076] In the table, L represents brightness; a represents red and green colors; b represents yellow and blue colors; and C represents color saturation.

[0077] Table 2 is the color detection data of the plastic products processed in Example 1 and Comparative Example 1 before and after UV irradiation

[0078]

[0079]

[0080] As can be seen from Table 1, the color vividness of the colored titanium dioxide prepared in the Examples of the present invention is significantly higher than that of the Comparative Examples, with Example 1 having the best coloring effect. Table 2 also shows that the color of Example 1 and Comparative Example 1 remains essentially unchanged after UV irradiation, while the color of Comparative Example 1 becomes significantly lighter and darker.

[0081] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing colored titanium dioxide, characterized in that: include: Providing titanium dioxide pigments with a surface coated with silicon dioxide; Under the condition of pH value of 6.5-7.5, sodium aluminate and pigment are reacted to coat the surface of the titanium dioxide pigment with organic pigment.

2. The preparation method according to claim 1, characterized in that The preparation process of the titanium dioxide pigment coated with silicon dioxide comprises: heating the titanium dioxide slurry to 70-90° C., adjusting the pH value to 9.5-10.5, and reacting with a sodium silicate solution while maintaining the pH value at 9.5-10.

5.

3. The preparation method according to claim 2, characterized in that The mass ratio of titanium dioxide in the titanium dioxide slurry to sodium silicate in the sodium silicate solution is (15-25):1; And / or, the concentration of titanium dioxide in the titanium dioxide slurry is 300 g / L-400 g / L, and the mass fraction of the sodium silicate solution is 20%-35%.

4. The preparation method according to claim 2, characterized in that The addition rate of the sodium silicate solution is 0.5 mL / min-5 mL / min; and / or, adding hydrochloric acid solution during the reaction to maintain the pH value of the system at 9.5-10.5; And / or, the D50 of the titanium dioxide particles in the titanium dioxide slurry is 0.20 μm-0.35 μm.

5. The preparation method according to any one of claims 2 to 4, characterized in that The process of coating the titanium dioxide pigment surface with organic pigment includes: after the sodium silicate solution is added, adjusting the pH value to 6.5-7.5, adding pigment, sodium aluminate and inorganic acid for reaction, and controlling the reaction temperature to 70°C-90°C.

6. The preparation method according to claim 5, characterized in that During the reaction of adding pigment, sodium aluminate and inorganic acid, a mixed solution formed by the pigment and inorganic acid and a sodium aluminate solution are added simultaneously; Alternatively, a mixed solution of pigment and sodium aluminate and an inorganic acid solution are added simultaneously.

7. The preparation method according to claim 6, characterized in that The mass ratio of the added pigment to the sodium aluminate is (0.05-0.30):1, and the mass ratio of the titanium dioxide in the titanium dioxide slurry to the added sodium aluminate is (55-70):

1.

8. The preparation method according to claim 6, characterized in that The pH value is adjusted to 6.5-7.5 by adjusting the amount of the inorganic acid added; And / or, the inorganic acid is dilute hydrochloric acid with a mass fraction of 3%-5%.

9. The preparation method according to claim 6 or 7, characterized in that: After the pigment and sodium aluminate are added, the mixture is kept warm for 0.2-1.0 hours, followed by solid-liquid separation, and the obtained solid material is washed and dried; and / or, adding a mixed solution of pigment and sodium aluminate and an inorganic acid solution simultaneously, controlling the addition rate of the mixed solution to be 0.5 mL / min-2.0 mL / min; And / or, the color of the pigment is selected from at least one of yellow, red and blue.

10. A colored titanium dioxide, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

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