Titanium dioxide for decorative paper and preparation method thereof

Abstract

The present invention discloses a titanium dioxide powder for decorative paper and a preparation method thereof. The titanium dioxide powder comprises a titanium dioxide substrate and a coating layer located on the surface of the titanium dioxide substrate. The coating layer comprises, from the inside out, at least a boron-doped calcium phosphate coating layer and a zinc oxide coating layer. The titanium dioxide powder provided herein has excellent light resistance and is well suited for decorative paper.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium dioxide preparation, and particularly relates to titanium dioxide for decorative paper and a preparation method thereof. Background Art

[0002] The growth of the real estate industry has boosted the decorative paper market. In particular, with the development of laminate flooring, impregnated paper-faced wood-based panels, furniture, and decoration, my country's decorative paper industry has entered a period of vigorous growth. As people's demands for a better quality of life increase, so too do their expectations for paper. Titanium dioxide is being widely used, particularly in applications requiring thin paper with high strength, whiteness, brightness, and low penetration.

[0003] In the application of decorative paper systems, titanium dioxide plays a decisive role in various performance indicators, particularly lightfastness. However, due to its inherent lattice defects, long-term exposure to UV light can catalyze the free radical oxidative decomposition of the surrounding organic matrix, causing yellowing, gloss loss, and powdering of the organic matrix, seriously affecting its performance and shortening its service life. Titanium dioxide surface coating can mask lattice defects, reduce the catalytic effect of titanium dioxide, and improve its dispersibility in organic matrices. Therefore, surface coating modification is crucial to expanding titanium dioxide's application market and developing high-performance titanium dioxide products.

[0004] Patent CN111410853B discloses a titanium dioxide pigment and a method for its manufacture, proposing to coat the surface of titanium dioxide particles with calcium phosphate. This method can significantly inhibit the blackening or graying of decorative paper and improve light resistance. However, due to the risk of calcium phosphate re-dissolving during the subsequent coating and pH adjustment process, the product viscosity will be higher, which is not conducive to coating and also reduces light resistance. Summary of the Invention

[0005] The purpose of the present invention is to provide a titanium dioxide for decorative paper and a preparation method thereof in order to solve the deficiencies of the prior art.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] A titanium dioxide for decorative paper, characterized by comprising a titanium dioxide substrate and a coating layer located on the surface of the titanium dioxide substrate, wherein the coating layer comprises at least a boron-doped calcium phosphate film layer and a zinc oxide film layer from the inside to the outside.

[0008] Preferably, the boron-doped calcium phosphate film layer is formed by reacting a boron source, a calcium source and a phosphate source in a titanium dioxide-based material slurry at a pH of 9.5 to 10.0.

[0009] Preferably, the amount of the boron source, calculated as H3BO3, is 1.0-2.0% of the mass of the titanium dioxide substrate; the amount of the phosphoric acid source, calculated as P2O5, is 1.0-3.0% of the mass of the titanium dioxide substrate; the amount of the calcium source, calculated as CaO, is 3.0-4.0% of the mass of the titanium dioxide substrate.

[0010] Preferably, the calcium source is calcium nitrate.

[0011] Preferably, the zinc oxide film layer is formed by reacting a zinc source in a titanium dioxide-based material slurry at a pH of 8.0 to 9.0, and the amount of the zinc source, calculated as ZnO, is 1.0 to 2.0% of the mass of the titanium dioxide substrate.

[0012] Preferably, the coating layer further includes an aluminum oxide film layer located on the outer surface of the zinc oxide film layer.

[0013] The method for preparing titanium dioxide for decorative paper as described above comprises the following steps:

[0014] An uncoated titanium dioxide-based material slurry is sequentially coated with a boron-doped calcium phosphate film layer and a zinc oxide film layer to obtain the titanium dioxide for decorative paper.

[0015] Preferably, the boron-doped calcium phosphate film coating method is:

[0016] The temperature of the titanium dioxide-based material slurry is adjusted to 70-80°C, and then a phosphoric acid source, a boron source and a calcium source are added. The temperature is raised to 85-95°C, the pH is adjusted to 9.5-10.0, and the boron-doped calcium phosphate film layer is obtained after aging. The amount of the boron source, calculated as H3BO3, is 1.0-2.0% of the mass of the titanium dioxide substrate; the amount of the phosphoric acid source, calculated as P2O5, is 1.0-3.0% of the mass of the titanium dioxide substrate; and the amount of the calcium source, calculated as CaO, is 3.0-4.0% of the mass of the titanium dioxide substrate.

[0017] Preferably, the zinc oxide film coating step is:

[0018] A zinc source is added to a titanium dioxide-based material slurry coated with a boron-doped calcium phosphate film layer, the slurry pH is adjusted to 8.0-9.0, and the zinc oxide film layer is formed after aging; the amount of the zinc source, calculated as ZnO, is 1.0-2.0% of the mass of the titanium dioxide substrate.

[0019] Preferably, the zinc oxide coating further includes an aluminum oxide coating, and the aluminum oxide coating step is:

[0020] An aluminum source and a pH regulator are added simultaneously to a titanium dioxide-based material slurry coated with a boron-doped calcium phosphate film layer and a zinc oxide film layer, the pH is maintained at 8.0-9.0, and an aluminum oxide film layer is formed after aging.

[0021] The titanium dioxide provided in this application has excellent light resistance and can be well applied in decorative paper. DETAILED DESCRIPTION

[0022] The present invention provides titanium dioxide for decorative paper, comprising a titanium dioxide substrate and a coating layer located on the surface of the titanium dioxide substrate, wherein the coating layer comprises at least a boron-doped calcium phosphate film layer and a zinc oxide film layer from the inside to the outside.

[0023] The present invention first coats the surface of a titanium dioxide substrate with a layer of boron-doped calcium phosphate. The addition of boron causes structural changes in the calcium phosphate. Specifically, the addition of boron saturates the P=O bonds in the [PO4] tetrahedrons, forming a network structure. This promotes the formation of [BO4] and [BPO4] groups. The high bond energy of the BO bond further completes the calcium phosphate network, thereby preventing degradation of titanium dioxide and improving light resistance. Furthermore, the high bond energy of the BO bond and the calcium phosphate network structure prevent calcium phosphate dissolution, resolving the problem of calcium phosphate dissolution affecting slurry viscosity in prior art.

[0024] A layer of zinc oxide film is coated on the surface of calcium phosphate. The electrons in its valence band can accept the energy in ultraviolet rays and undergo transitions, which can effectively block the contact between oxygen and the titanium dioxide surface, further improving the light resistance of the product.

[0025] Therefore, the titanium dioxide provided in this application has excellent light resistance and can be well applied in decorative paper.

[0026] Preferably, the boron-doped calcium phosphate film layer is formed by reacting a boron source, a calcium source and a phosphoric acid source in a titanium dioxide-based material slurry at a pH of 9.5 to 10.0.

[0027] Preferably, the amount of boron source, calculated as H3BO3, is 1.0-2.0% of the mass of the titanium dioxide substrate; the amount of phosphoric acid source, calculated as P2O5, is 1.0-3.0% of the mass of the titanium dioxide substrate; and the amount of calcium source, calculated as CaO, is 3.0-4.0% of the mass of the titanium dioxide substrate.

[0028] Preferably, the zinc oxide film layer is formed by reacting a zinc source in a titanium dioxide-based material slurry at a pH of 8.0 to 9.0.

[0029] Preferably, the amount of zinc source used, calculated as ZnO, is 1.0-2.0% of the mass of the titanium dioxide substrate.

[0030] Preferably, the coating layer further includes an aluminum oxide film layer located on the outer surface of the zinc oxide film layer, and more preferably a loose boehmite aluminum oxide film layer, which can improve the dispersibility of the product and further improve the light resistance of the product.

[0031] The present application also provides a method for preparing the titanium dioxide for decorative paper as described above, comprising the following steps:

[0032] An uncoated titanium dioxide-based material slurry is sequentially coated with a boron-doped calcium phosphate film layer and a zinc oxide film layer to obtain the titanium dioxide for decorative paper.

[0033] Preferably, the concentration of the titanium dioxide-based material slurry is 300 to 350 g / L, calculated as titanium dioxide.

[0034] Preferably, the boron-doped calcium phosphate film coating step is:

[0035] The temperature of the titanium dioxide-based material slurry is adjusted to 70-80°C, and then a phosphoric acid source is added first, and the addition time is preferably 20-30 minutes. After aging for 15-25 minutes, a boron source is added, and the boron source addition time is preferably 20-30 minutes. After aging for 10-20 minutes, a calcium source is added, and the calcium source is added for 40-60 minutes and aging for 20-40 minutes. The order of these three raw materials can also be changed. Then the temperature is raised to 85-95°C, and after aging for 40-50 minutes, the pH is adjusted to 9.5-10.0. After aging for 20-40 minutes, a boron-doped calcium phosphate film layer is obtained; the amount of boron source is calculated as H3BO3, which is 1.0-2.0% of the mass of the titanium dioxide substrate; the amount of phosphoric acid source is calculated as P2O5, which is 1.0-3.0% of the mass of the titanium dioxide substrate; the amount of calcium source is calculated as CaO, which is 3.0-4.0% of the mass of the titanium dioxide substrate. The phosphate source is preferably one or more of Na2HPO4, Na3PO4, (NaPO3)6, and Na4P2O7, and is added as a solution at a concentration of 90-100 g / L, calculated as PO5. The boron source can be sodium borate, boric acid, calcium borate, etc., preferably boric acid, and is added as a solution at a concentration of 30-50 g / L, calculated as H3BO3. The calcium source can be calcium chloride, calcium nitrate, etc., preferably calcium nitrate, and is added as a solution at a concentration of 30-50 g / L, calculated as CaO. Ammonia water, sodium hydroxide, potassium hydroxide, etc. are preferably used for pH adjustment.

[0036] When light irradiates TiO2 surface 4+ and is reduced to Ti 3+ , Ti generated by the reaction 3+ Unstable, with the extension of exposure time, Ti 3+ The more it accumulates, the darker the color of the system will become, the corresponding ΔE will also increase, and the light resistance will deteriorate; Therefore, the present invention preferably uses Ca(NO3)2 as the calcium source. After washing with water, most of the nitrate will be washed away by water, but some will remain in the film layer, and the blackened Ti generated by the reaction will be 3+ The residual NO 3- Oxidation to Ti4+ , thereby improving the light resistance of the product.

[0037] Preferably, the zinc oxide film coating step is:

[0038] A zinc source is added to a titanium dioxide-based material slurry coated with a boron-doped calcium phosphate film. The zinc source is preferably added for 40 to 60 minutes. After aging for 15 to 25 minutes, the slurry pH is adjusted to 8.0 to 9.0. Zinc ions gradually precipitate on the titanium dioxide surface under this pH condition, forming a zinc oxide film after aging. The zinc source is used in an amount, calculated as ZnO, of 1.0 to 2.0% of the mass of the titanium dioxide substrate. The zinc source is preferably ZnCl2 or ZnSO4, and is added in the form of a solution with a concentration, calculated as ZnO, of 80 to 200 g / L.

[0039] Preferably, the zinc oxide coating further includes aluminum oxide coating, and the aluminum oxide coating steps are:

[0040] An aluminum source and a pH adjuster are simultaneously added to a titanium dioxide-based material slurry coated with a boron-doped calcium phosphate film and a zinc oxide film. The aluminum source is added for 90 to 120 minutes, the pH is maintained at 8.0 to 9.0, and the slurry is aged for 20 to 40 minutes to form a loose boehmite aluminum oxide film. The aluminum source is preferably aluminum sulfate or sodium metaaluminate and is added as a solution with a concentration of 150 to 180 g / L (as Al2O3). The aluminum source is used in an amount of 3.0 to 4.0% of the total mass of the titanium dioxide substrate, as Al2O3.

[0041] Preferably, after forming the aluminum oxide film layer, the following steps are further included:

[0042] The pH of the obtained slurry is 5.0-6.0, and it is aged for 1-3 hours. The aged slurry is then washed with water to remove the flash powder to obtain titanium dioxide. Finally, the slurry is adjusted to be acidic to facilitate water washing.

[0043] Example 1

[0044] The slurry with qualified sand-grinding particle size is introduced into the coating tank, and the slurry concentration is controlled to 300g / L (calculated as TiO2). At the same time, the temperature is raised to 80℃; 2.5% (NaPO3)6 (calculated as P2O5) is added within 20min and homogenized for 20min; 1.0% H3BO3 solution is added within 30min and homogenized for 15min; 3.3% Ca(NO3)2 solution is added within 60min; the temperature is raised to 90℃ and homogenized for 45min; ammonia water is added to adjust the pH to 10.0, 45m After adjusting the pH, homogenize for 30 minutes; add 1.0% ZnCl2 solution within 60 minutes and homogenize for 20 minutes; adjust the pH to 8.5 with H2SO4, adjust it within 20 minutes, and homogenize for 20 minutes; add 3.0% NaAlO2 solution and dilute H2SO4 solution within 90 minutes, maintain the pH = 8.5 in parallel, and homogenize for 30 minutes; adjust the pH to 5.5 with dilute H2SO4, adjust for 30 minutes, and homogenize for 120 minutes; wash with water, flash evaporate, and steam powder to obtain the product.

[0045] Example 2

[0046] The slurry with qualified sand-grinding particle size is introduced into the coating tank, and the slurry concentration is controlled to 300g / L (calculated as TiO2). At the same time, the temperature is raised to 80℃; 2.0% (NaPO3)6 (calculated as P2O5) is added within 20min and homogenized for 20min; 1.5% H3BO3 solution is added within 30min and homogenized for 15min; 3.0% Ca(NO3)2 solution is added within 60min; the temperature is raised to 90℃ and homogenized for 45min; ammonia water is added to adjust the pH to 10.0, 45m After adjusting the pH, homogenize for 30 minutes; add 1.5% ZnCl2 solution within 60 minutes and homogenize for 20 minutes; adjust the pH to 8.5 with H2SO4, adjust it within 20 minutes, and homogenize for 20 minutes; add 3.5% NaAlO2 solution and dilute H2SO4 solution within 90 minutes, maintain the pH = 8.0 in parallel, and homogenize for 30 minutes; adjust the pH to 5.5 with dilute H2SO4, adjust for 30 minutes, and homogenize for 120 minutes; wash with water, flash evaporate, and steam powder to obtain the product.

[0047] Example 3

[0048] The slurry with qualified sand-grinding particle size is introduced into the coating tank, and the slurry concentration is controlled to 300g / L (calculated as TiO2). At the same time, the temperature is raised to 80℃; 3% (NaPO3)6 (calculated as P2O5) is added within 20min and homogenized for 20min; 2.0% H3BO3 solution is added within 30min and homogenized for 15min; 4% Ca(NO3)2 solution is added within 60min; the temperature is raised to 90℃ and homogenized for 45min; ammonia water is used to adjust the pH to 10.0 and homogenize for 45min. After adjustment, homogenize for 30 minutes; add 2.0% ZnCl2 solution within 60 minutes and homogenize for 20 minutes; adjust the pH to 8.5 with H2SO4, adjust within 20 minutes, and homogenize for 20 minutes; add 4.0% NaAlO2 solution and dilute H2SO4 solution within 90 minutes, maintain parallel flow pH = 9.0, and homogenize for 30 minutes; adjust the pH to 5.5 with dilute H2SO4, adjust for 30 minutes, and homogenize for 120 minutes; wash with water, flash evaporate, and steam powder to obtain the product.

[0049] Comparative Example 1 (Undoped with Boron, Uncoated Zinc Oxide)

[0050] The slurry with qualified sand-milling particle size is introduced into the coating tank, and the slurry concentration is controlled to 300g / L (in terms of TiO2), and the temperature is raised to 80℃ at the same time; 2.5% (NaPO3)6 (in terms of P2O5) is added within 20 minutes and homogenized for 20 minutes; 3.3% Ca(NO3)2 solution is added within 60 minutes; the temperature is raised to 90℃ and homogenized for 45 minutes; ammonia water is used to adjust the pH to 10.0, and the adjustment is completed within 45 minutes, and the homogenization is carried out for 30 minutes; H2SO4 is used to adjust the pH to 8.5, and the adjustment is completed within 20 minutes, and the homogenization is carried out for 20 minutes; 3.0% NaAlO2 solution and dilute H2SO4 solution are added within 90 minutes, and the pH is maintained at 8.5 in parallel, and the homogenization is carried out for 30 minutes; the pH is adjusted to 5.5 with dilute H2SO4, and the adjustment is carried out for 30 minutes, and the homogenization is carried out for 120 minutes; the product is obtained by water washing, flash evaporation, and steam powder.

[0051] Comparative Example 2 (Undoped with Boron)

[0052] The slurry with qualified sand-grinding particle size is introduced into the coating tank, and the slurry concentration is controlled to 300g / L (calculated as TiO2). At the same time, the temperature is raised to 80℃; 2.5% (NaPO3)6 (calculated as P2O5) is added within 20min and homogenized for 20min; 3.3% Ca(NO3)2 solution is added within 60min; the temperature is raised to 90℃ and homogenized for 45min; the pH is adjusted to 10.0 with ammonia water, and it is adjusted within 45min, and homogenized for 30min; the pH is adjusted to 8.5 with H2SO4, and it is homogenized for 20min. within 60 minutes, add 1.0% ZnCl2 solution and homogenize for 20 minutes; adjust the pH to 8.5 with H2SO4, adjust within 20 minutes, and homogenize for 20 minutes; within 90 minutes, add 3.0% NaAlO2 solution and dilute H2SO4 solution, maintain the pH at 8.5 in parallel, and homogenize for 30 minutes; adjust the pH to 5.5 with dilute H2SO4, adjust for 30 minutes, and homogenize for 120 minutes; wash with water, flash evaporate, and steam powder to obtain the product.

[0053] The light resistance of the titanium dioxide provided in Examples 1 to 3 and Comparative Examples 1 to 2 was evaluated using a conventional method. The results are shown in Table 1.

[0054] Table 1

[0055] sample Average ΔE / 100h Comparative Example 1 2.78 Comparative Example 2 2.54 Example 1 2.29 Example 2 1.89 Comparative Example 3 1.67

[0056] It can be seen from the above data that the light resistance of the titanium dioxide prepared by the present invention in papermaking is better than that of comparative examples 1 and 2.

[0057] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the claims and their equivalents.

Claims

1. A titanium dioxide for decorative paper, characterized in that: The invention comprises a titanium dioxide substrate and a coating layer located on the surface of the titanium dioxide substrate, wherein the coating layer comprises at least a boron-doped calcium phosphate film layer and a zinc oxide film layer from the inside to the outside; the boron-doped calcium phosphate film layer is formed by reacting a boron source, a calcium source and a phosphate source in a titanium dioxide-based material slurry at a pH of 9.5-10.

0.

2. The titanium dioxide for decorative paper according to claim 1, wherein The amount of the boron source, calculated as H3BO3, is 1.0-2.0% of the mass of the titanium dioxide substrate; the amount of the phosphoric acid source, calculated as P2O5, is 1.0-3.0% of the mass of the titanium dioxide substrate; and the amount of the calcium source, calculated as CaO, is 3.0-4.0% of the mass of the titanium dioxide substrate.

3. The titanium dioxide for decorative paper according to claim 1, wherein: The calcium source is calcium nitrate.

4. The titanium dioxide for decorative paper according to claim 1, wherein: The zinc oxide film layer is formed by reacting a zinc source in a titanium dioxide-based material slurry at a pH of 8.0-9.

0. The amount of the zinc source, calculated as ZnO, is 1.0-2.0% of the mass of the titanium dioxide substrate.

5. The titanium dioxide for decorative paper according to claim 1, wherein: The coating layer further includes an aluminum oxide film layer located on the outer surface of the zinc oxide film layer.

6. The method for preparing titanium dioxide for decorative paper according to any one of claims 1 to 4, characterized in that: The following steps are involved: An uncoated titanium dioxide-based material slurry is sequentially coated with a boron-doped calcium phosphate film layer and a zinc oxide film layer to obtain the titanium dioxide for decorative paper.

7. The method for preparing titanium dioxide for decorative paper according to claim 6, wherein: The boron-doped calcium phosphate film coating method is: The temperature of the titanium dioxide-based material slurry is adjusted to 70-80° C., and then a phosphoric acid source, a boron source, and a calcium source are added. The temperature is raised to 85-95° C., the pH is adjusted to 9.5-10.0, and the boron-doped calcium phosphate film layer is obtained after aging. The amount of the boron source, calculated as H3BO3, is 1.0-2.0% of the mass of the titanium dioxide substrate; the amount of the phosphoric acid source, calculated as P2O5, is 1.0-3.0% of the mass of the titanium dioxide substrate; and the amount of the calcium source, calculated as CaO, is 3.0-4.0% of the mass of the titanium dioxide substrate.

8. The method for preparing titanium dioxide for decorative paper according to claim 6, wherein: The zinc oxide film coating step is: A zinc source is added to a titanium dioxide-based material slurry coated with a boron-doped calcium phosphate film layer, the slurry pH is adjusted to 8.0-9.0, and the zinc oxide film layer is formed after aging; the amount of the zinc source, calculated as ZnO, is 1.0-2.0% of the mass of the titanium dioxide substrate.

9. The method for preparing titanium dioxide for decorative paper according to claim 6, wherein: The zinc oxide coating further includes an aluminum oxide coating, and the aluminum oxide coating steps are: An aluminum source and a pH regulator are added simultaneously to a titanium dioxide-based material slurry coated with a boron-doped calcium phosphate film layer and a zinc oxide film layer, the pH is maintained at 8.0-9.0, and an aluminum oxide film layer is formed after aging.