CN113372736A

CN113372736A - Titanium dioxide coating material, preparation method and application thereof

Info

Publication number: CN113372736A
Application number: CN202110636758.4A
Authority: CN
Inventors: 鲍领翔; 武超; 费明; 谢秉昆
Original assignee: Zhengtai New Material Technology Co ltd
Current assignee: Zhengtai New Material Technology Co ltd
Priority date: 2021-06-08
Filing date: 2021-06-08
Publication date: 2021-09-10
Anticipated expiration: 2041-06-08
Also published as: CN113372736B

Abstract

The invention discloses a titanium dioxide coating material, a preparation method and application thereof, and relates to the technical field of titanium dioxide preparation. The preparation method of the titanium dioxide coating material comprises the following steps: mixing the titanium dioxide slurry with sodium metasilicate to form silicon coating, and controlling the pH value of the system to be 11-13 by using organic acid in the coating process. Sodium metasilicate is used as a raw material, organic acid is used as a neutralizer and a film-forming agent to complex with silica sol molecules, the pH value of the coating process is controlled to be 11-13, the organic acid is used as a neutralizer and a film-forming agent, the activity of the coating process under high pH is improved, the coating process under high pH is realized, the reaction rate of the coating process is slower, and a compact coating film layer is formed. In addition, the preparation method provided by the embodiment of the invention adjusts the pH value by using the organic acid, so that the formed coating material has no agglomeration phenomenon and high density, and the weather resistance of the coating material is obviously improved.

Description

Titanium dioxide coating material, preparation method and application thereof

Technical Field

The invention relates to the technical field of titanium dioxide preparation, and particularly relates to a titanium dioxide coating material, and a preparation method and application thereof.

Background

Titanium dioxide is an important inorganic chemical pigment, the main component of which is titanium dioxide, and the titanium dioxide has important application in the industries of paint, printing ink, paper making, plastic rubber, chemical fiber, ceramic and the like. However, titanium dioxide has strong photocatalytic activity due to its semiconductor properties, and can degrade organic substances in contact with titanium dioxide under the irradiation of sunlight, especially ultraviolet rays, thereby causing the phenomena of yellowing, pulverization and the like of the coating. The surface of the titanium dioxide is coated with the compact silicon oxide film, so that the weather resistance and chalking resistance of the titanium dioxide pigment can be effectively improved.

The prior silicon oxide coating process generally uses sodium metasilicate as a coating agent, inorganic acid such as sulfuric acid, hydrochloric acid and the like as a neutralizer, and the coating pH value is generally controlled between 8 and 11. This is because silicon has high reactivity at pH 8 to 11, and contributes to film formation coating and inhibition of nucleation coating.

However, the conventional silicon oxide coating method generally has the following problems: (1) the pH value is controlled between 8 and 11, the reaction speed is high and is not easy to control, the density of a generated film layer is not uniform, and when the pH value is more than 11, the activity is low, the reaction speed is low and the film can not be formed on the surface of the titanium dioxide; (2) in the silicon coating process, titanium dioxide particles are easy to agglomerate, so that silicon oxide cannot form a continuous and uniform film layer on the surface of a single particle, and the weather resistance is not obviously improved.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a titanium dioxide coating material and a preparation method thereof, and aims to improve the compactness of a silicon coating film layer and improve the weather resistance of the coating material.

The invention also aims to provide the application of the titanium dioxide coating material in the preparation of paint or ink.

The invention is realized by the following steps:

in a first aspect, the present invention provides a method for preparing a titanium dioxide coating material, comprising: mixing the titanium dioxide slurry with sodium metasilicate to form silicon coating, and controlling the pH value of the system to be 11-13 by using organic acid in the coating process.

In a second aspect, the present invention provides a titania-coated material produced by the production method of the foregoing embodiment.

In a third aspect, the invention provides the use of the titanium dioxide coating material in the preparation of a coating or ink.

The invention has the following beneficial effects: the inventor improves the raw material and the operating condition for coating the silicon dioxide on the surface of the titanium dioxide, uses sodium metasilicate as the raw material, and adopts organic acid to control the pH value of the coating process to be 11-13, and the organic acid is used as a neutralizer and a film-forming agent to be complexed with silica sol molecules, so that the activity of the coating process under high pH is improved, the coating process is carried out under high pH, the reaction rate of the coating process is low, and a compact coating film layer is formed. In addition, the preparation method provided by the embodiment of the invention adjusts the pH value by using the organic acid, so that the formed coating material has no agglomeration phenomenon and high density, and the weather resistance of the coating material is obviously improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a scanning electron micrograph of a product obtained in a comparative example;

FIG. 2 is a scanning electron micrograph of the product obtained in the example.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The inventor finds that: in the prior art, the pH value is generally controlled to be between 8 and 11, the reaction speed is high and is difficult to control, and the density of a generated film layer is not uniform, but the film formation on the surface of the titanium dioxide can not be realized due to low reaction activity and low reaction speed after the reaction pH value is increased. In addition, in the prior art, the easy agglomeration phenomenon of titanium dioxide particles is probably related to the reaction of inorganic acid, and because of the agglomeration phenomenon, silicon oxide cannot form a continuous and uniform film layer on the surface of a single particle, which is not beneficial to improving the weather resistance.

Therefore, the inventor improves the raw materials for forming the silicon coating, controls the pH value by matching with organic acid, and controls the pH value of the system to be 11-13, so that the formed titanium dioxide coating material has the advantages of high density, no agglomeration phenomenon, good weather resistance and the like.

Different from the traditional silicon coating process, the silicon dioxide coating process adopts organic acid as a neutralizer and a film forming agent to complex with silica sol molecules, so that the activity of the silicon dioxide coating process is improved under high PH, the silicic acid polymerization speed is low under the condition, the silicon dioxide is uniformly coated on the surface of titanium dioxide, and a continuous, uniform and compact silicon oxide film is formed by matching with processes such as high alkalization, low acidification and the like.

The embodiment of the invention provides a preparation method of a titanium dioxide coating material, which comprises the following steps:

s1 preparation of titanium dioxide slurry

The titanium dioxide slurry is obtained by mixing titanium dioxide and water, and the pH value of the titanium dioxide slurry is adjusted to 11-13 by adopting alkali liquor, so that the pH value of the titanium dioxide slurry reaches the pH value required by the coating process.

In practical operation, the preparation process of the titanium dioxide slurry comprises the following steps: mixing titanium dioxide and water to obtain titanium dioxide base material, adjusting pH value to 11-13 with alkali liquor at 85-95 deg.C, and performing alkalization for 1-2 h.

Specifically, the adjusted temperature may be 85 ℃, 90 ℃, 95 ℃ or the like, or may be any value between the above adjacent temperature values. The alkaline solution can be common sodium hydroxide solution, potassium hydroxide solution, etc., and the end point of pH value adjustment can be 11.0, 11.5, 12.0, 12.5, 13.0, etc. The uniformity of the whole slurry is higher through the alkalization treatment for 1-2h, and the uniformity of the coating material is improved.

In some embodiments, the concentration of titanium dioxide binder is 150-350g/L, such as 150g/L, 200g/L, 250g/L, 300g/L, 350g/L, and the like.

S2 silicon film coating

Mixing the titanium dioxide slurry with sodium metasilicate to form silicon coating, and controlling the pH value of the system to be 11-13 by using organic acid in the coating process. Preferably, the pH value of the system is controlled to be 12-12.5 by using organic acid in the coating process. The inventor takes high-modulus sodium metasilicate as a raw material, adopts organic acid to regulate and control the pH value, can form a film under the condition of higher pH value, has slower reaction rate, is easier to form a compact silicon film, does not agglomerate titanium dioxide, and has good weather resistance.

In order to further control the reaction rate and form a more compact film, the sodium metasilicate solution and the organic acid are added into the titanium dioxide slurry dropwise, the adding time of the sodium metasilicate solution is 200-400min (such as 200min, 250min, 300min, 350min, 400min, and the like), and the organic acid is added dropwise to adjust the pH value within the specified range. The reaction proceeds more slowly by adding the starting materials in the form of drops and controlling the time of addition.

Specifically, the organic acid is selected from at least one of formic acid, acetic acid, oxalic acid, tartaric acid, citric acid, sulfamic acid and ethylenediamine tetraacetic acid; preferably, the organic acid is selected from at least one of acetic acid, tartaric acid and citric acid. By regulating and controlling the selection of the organic acid, the occurrence of agglomeration can be further avoided, and the weather resistance of the material can be ensured.

It should be noted that, in the embodiment of the present invention, the organic acid is both a neutralizing agent and a silicon dioxide film forming agent, and the organic acid and sodium oxide in the sodium silicate may form organic sodium, which serves as a buffering agent, so as to facilitate uniform coating of the silicon dioxide on the surface of the titanium dioxide.

In some embodiments, SiO in the sodium metasilicate starting material is used₂With Na₂The molar ratio of O is 2.5-3.5, and the high-modulus sodium silicate can be used for effectively reducingThe amount of organic acid used and the effect of Na ions on silica coating.

In some embodiments, the ratio of the mass of silica in the sodium metasilicate to the mass of titanium dioxide in the titanium dioxide slurry is 2-4:100 (e.g., 2:100, 3:100, 4:100, etc.). The thickness of the silicon film is regulated and controlled by further controlling the material of the sodium metasilicate, so that the comprehensive performance of the coating material is improved on the premise of ensuring the weather resistance.

S3, acidizing

After the sodium metasilicate solution is dripped, the pH value is adjusted to 3-5 by adopting organic acid, then acidification treatment is carried out for 1-2h, and the compactness of the silicon film can be improved after the acidification treatment. Specifically, the pH may be 3, 4, 5, etc.

Specifically, the selection range of the organic acid is the same as that in S2, and will not be described herein.

S4, coating with aluminum film

The aluminum film coating can be carried out by mixing the slurry after the acidification treatment with aluminum salt and alkali liquor by adopting the prior art.

The operation temperature of the aluminum film coating is 55-75 ℃, the pH value is controlled to be 6-8 by alkali liquor, aluminum salt and alkali liquor are added, then the mixture is aged for 1-2 hours, and the silicon dioxide coating material can be obtained by the conventional steps of water washing, flash evaporation, steam grinding and the like.

The embodiment of the invention also provides a titanium dioxide coating material, which is prepared by the preparation method of any one of the embodiments, has the advantages of high film density, no agglomeration, good weather resistance and the like, and can be applied to preparation of paint or ink.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment provides a preparation method of a titanium dioxide coating material, which comprises the following steps:

(1) mixing the sanded titanium dioxide and water to prepare a base material with the concentration of 250g/L, heating to 90 ℃, adjusting the pH value to 12 by adopting 32% sodium hydroxide solution, and preserving heat and aging for 1.5 hours to obtain titanium dioxide slurry.

(2) Dropwise adding a sodium metasilicate aqueous solution with the modulus n being 3 into the titanium dioxide slurry, wherein the adding amount is 3 percent of the mass of the titanium dioxide (by using SiO)₂Metering), the dropping time is 300 min; while controlling the pH to 12 with oxalic acid.

(3) After the sodium metasilicate aqueous solution is added dropwise, the pH value is adjusted to 4 by oxalic acid, and the mixture is kept warm and aged for 1.5 hours.

(4) Reducing the temperature of the slurry obtained in the step (3) to 60 ℃, and adding 3 percent (SiO) in parallel₂Calculated) aluminum salt (100g/L aluminum chloride solution) and sodium hydroxide solution, the pH value is kept at 7, aluminum film coating is carried out, aging is carried out for 2 hours, and then washing, flash evaporation and steam grinding are carried out to obtain the product 1.

Example 2

(1) mixing the sanded titanium dioxide and water to prepare a base material with the concentration of 350g/L, heating to 95 ℃, adjusting the pH to 13 by adopting 32% sodium hydroxide solution, and preserving heat and aging for 1 hour.

(2) Dropwise adding an aqueous solution of sodium metasilicate with the modulus n being 2.5 into the titanium dioxide slurry, wherein the adding amount is 2 percent of the titanium dioxide (by SiO)₂Metering), the dropping time is 200 min; while controlling the pH to 11 with acetic acid.

(3) After the sodium metasilicate aqueous solution is dripped, acetic acid is used for adjusting the pH value to 3, and the temperature is kept for aging for 2 hours.

(4) Reducing the temperature of the slurry obtained in the step (3) to 60 ℃, and adding 3 percent (SiO) in parallel₂Calculated) aluminum salt (100g/L aluminum chloride solution) and sodium hydroxide solution, the pH value is kept at 7, aluminum film coating is carried out, after aging is carried out for 2 hours, and then product 2 is obtained through water washing, flash evaporation and steam grinding.

Example 3

(1) mixing the sanded titanium dioxide and water to prepare a base material with the concentration of 150g/L, heating to 85 ℃, adjusting the pH value to 11 by using liquid alkali, and preserving heat and aging for 2 hours.

(2) Dividing the modulus n into3.5 aqueous solution of sodium metasilicate was added dropwise to the titanium dioxide slurry in an amount of 4% of the titanium dioxide (in terms of SiO)₂Metering), the dropping time is 400 min; while controlling the pH at 13 with tartaric acid.

(3) After the sodium metasilicate aqueous solution is added dropwise, the pH value is adjusted to 5 by tartaric acid, and the mixture is kept warm and aged for 1 hour.

(4) The temperature of the slurry was reduced to 60 ℃ and 3% (as SiO) was added concurrently₂Calculated) aluminum salt (100g/L aluminum chloride solution) and sodium hydroxide solution, the pH value is kept at 7, aluminum film coating is carried out, after aging is carried out for 2 hours, and then product 3 is obtained through water washing, flash evaporation and steam grinding.

Comparative example 1

This comparative example provides a process for the preparation of a titania-coated material, substantially the same process conditions as in example 1, except that: sulfuric acid is used instead of oxalic acid.

Comparative example 2

This comparative example provides a process for the preparation of a titania-coated material, substantially the same process conditions as in example 1, except that: step (2) pH was controlled to 9 with acetic acid.

Comparative example 3

This comparative example provides a process for the preparation of a titania-coated material, substantially the same process conditions as in example 1, except that: step (2) pH was controlled to 14 with acetic acid.

Comparative example 4

This comparative example provides a process for the preparation of a titania-coated material, substantially the same process conditions as in example 1, except that: the sodium metasilicate has a modulus of 1.

Test example 1

Acid solubility detection is carried out on the titanium dioxide samples of the examples and the comparative examples: a titanium dioxide sample is heated for 1 hour under oil bath at 175 ℃, diluted in ice water bath, and is subjected to complexation with hydrogen peroxide, and then the acid dissolution rate is measured by a visible spectrophotometer, and the result is shown in Table 1.

The titanium dioxide samples of the examples and the comparative examples were dispersed in acrylic resin for weather resistance evaluation, and color change after aging at 75 degrees for 1500 hours was measured by a xenon lamp rapid aging test, and the results are shown in table 1.

Note: the reference sample in Table 1 is commercially available rutile titanium dioxide.

TABLE 1 acid solubility and weather resistance test results

Sample numbering	Acid solubility%	DL^*	Da^*	Db^*	DE^*
						Example 1	4.6	-0.3	0.16	0.04	0.34
Example 2	6.9	-0.42	-0.07	0.17	0.46
						Example 3	3.4	-0.17	-0.13	0.2	0.29
Comparative example 1	12.2	-0.7	-0.37	0.15	0.81
						Comparative example 2	15.8	-0.85	-0.03	0.35	0.92
Comparative example 3	23.3	-1.31	-0.06	0.31	1.35
						Comparative example 4	8.7	-0.58	-0.05	0.23	0.62
Reference sample	10.2	-0.59	0.04	0.46	0.75

Test example 2

The scanning electron micrographs of the obtained products in comparative example 1 and example 1 were measured, and the results are shown in fig. 1-2, fig. 1 is the test result of comparative example 1, and fig. 2 is the test result of example 1.

As can be seen from the figure, the coating material prepared in example 1 is obviously more uniformly distributed, and more agglomeration phenomenon occurs in comparative example 1.

In summary, the embodiments of the present invention provide a titanium dioxide coating material, a preparation method and an application thereof, wherein the inventor improves raw materials and operating conditions for coating silicon dioxide on the surface of titanium dioxide, uses high-modulus sodium metasilicate as a raw material, adopts organic acid to control the pH of the coating process to be 11-13, and uses the organic acid as a neutralizing agent and a film-forming agent to complex with a silica sol molecule, thereby improving the activity of the coating material at high pH and realizing coating at high pH.

The preparation method in the embodiment of the invention has slower reaction rate in the coating process and can form a more compact coating film layer. In addition, the preparation method provided by the embodiment of the invention adjusts the pH value by using the organic acid, so that the formed coating material has no agglomeration phenomenon and high density, and the weather resistance of the coating material is obviously improved.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a titanium dioxide coating material is characterized by comprising the following steps: mixing the titanium dioxide slurry with sodium metasilicate to form silicon coating, and controlling the pH value of the system to be 11-13 by using organic acid in the coating process.

2. The preparation method according to claim 1, wherein the pH value of the system is controlled to be 12-12.5 by using an organic acid during the coating process.

3. The method according to claim 2, wherein the starting material of sodium metasilicate used is SiO₂With Na₂The molar ratio of O is 2.5-3.5;

preferably, the mass ratio of the silica in the sodium metasilicate to the titanium dioxide in the titanium dioxide slurry is 2-4: 100;

preferably, a sodium metasilicate solution and an organic acid are dropwise added to the titanium dioxide slurry, wherein the dropwise adding time of the sodium metasilicate solution is 200-400 min.

4. The preparation method according to claim 3, wherein after the sodium metasilicate solution is added dropwise, the pH is adjusted to 3-5 with an organic acid, and then acidification is performed for 1-2 hours.

5. The production method according to any one of claims 1 to 4, wherein the organic acid is at least one selected from the group consisting of formic acid, acetic acid, oxalic acid, tartaric acid, citric acid, sulfamic acid and ethylenediaminetetraacetic acid;

preferably, the organic acid is selected from at least one of acetic acid, tartaric acid and citric acid.

6. The method according to claim 4, further comprising mixing the acidified slurry with an aluminum salt and a lye to coat the aluminum film.

7. The method according to claim 1, wherein the titanium dioxide slurry is prepared by mixing titanium dioxide and water, and adjusting the pH to 11 to 13 with an alkali solution.

8. The production method according to claim 7, characterized in that the production process of the titanium dioxide slurry comprises: mixing titanium dioxide and water to obtain a titanium dioxide base material, adjusting the pH value to 11-13 by adopting alkali liquor at the temperature of 85-95 ℃, and then carrying out alkalization treatment for 1-2 h;

preferably, the concentration of the titanium dioxide binder is 150-350 g/L.

9. A titania-coated material produced by the production method according to any one of claims 1 to 8.

10. Use of the titanium dioxide coating material according to claim 9 in the preparation of coatings or inks.