Hollow spherical titanium dioxide and production method thereof

Abstract

The invention provides hollow spherical titanium dioxide and a production method thereof, and the production method comprises the following steps: carrying out initial depolymerization on calcined TiO2 particles, then adding a dispersing agent, grinding, dispersing, and heating in a water bath to prepare titanium dioxide slurry with the mass fraction of 40-200g / L; the preparation method comprises the following steps: firstly adding part of polyaluminum chloride into titanium dioxide slurry, adding part of titanium tetrachloride after ultrasonic reaction, slowly adding the rest of polyaluminum chloride and titanium tetrachloride in sequence after ultrasonic reaction for a period of time, and filtering after ultrasonic dispersion, heat preservation and aging to obtain particles I; uniformly mixing and dispersing the particles I, a dispersing agent and water, then adding modified silicon dioxide and an organic solvent, uniformly mixing, aging, centrifuging, washing, drying and grinding to obtain particles II; and dissolving the particles II in an acid solution for a period of time to obtain the porous silicon dioxide coated titanium dioxide hollow particles which can improve the compatibility of titanium dioxide and an ink system and avoid the agglomeration phenomenon.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide production, and more particularly, to a hollow spherical titanium dioxide and a production method thereof. Background Art

[0002] With the improvement of digital printing equipment in terms of printing quality, speed, and the range of substrates, digital printing materials, especially the development of electronic inks and toner, are indispensable. Moreover, with the increasingly fierce competition in the digital printing market, digital printing equipment suppliers have increased their R & D investment in new inks and toner. In addition to the continued advantages of water-based inks and enhanced durability, the development of various electronic inks such as solvent-based inks, eco-friendly inks, and UV inks has led to a diverse development trend of available inks.

[0003] Inks are mainly composed of binders, pigments or dyes, solvents, and additives. The ink layer is formed by the binder film-forming on the substrate. Among them, titanium dioxide is an important inorganic chemical pigment and has important uses in industries such as coatings, inks, papermaking, plastic rubber, chemical fibers, and ceramics. The surface of untreated titanium dioxide is generally coated with polar groups (such as hydroxyl groups), so titanium dioxide is prone to agglomeration due to polar adsorption or moisture absorption, becoming larger agglomerates with several weak connection interfaces and being difficult to disperse in organic solvents, thus greatly limiting its industrial applications; therefore, it is very necessary to perform surface modification on titanium dioxide to improve its dispersibility and compatibility in solvents and reduce secondary agglomeration. Summary of the Invention

[0004] The purpose of the present invention is to provide a hollow spherical titanium dioxide and a production method thereof, which can improve the compatibility of titanium dioxide with the ink system and avoid agglomeration.

[0005] The embodiments of the present invention are achieved through the following technical solutions:

[0006] A production method of a hollow spherical titanium dioxide, comprising the following steps:

[0007] S1. Grind and disperse the calcined TiO2 particles with a Raymond mill, control the dispersion fineness to the residue on a 600-mesh sieve ≤ 0.5%, then add water to make a slurry, and then add 0.2% - 0.5% of a dispersant (such as sodium hexametaphosphate, sodium silicate, sodium tripolyphosphate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium bromide), and perform secondary grinding and dispersion with a sand mill. Control the D50 of the slurry to be between 0.31 and 0.35, perform secondary water replenishment, prepare the slurry concentration to be between 40 - 200 g / L, put the slurry into a water bath at 45 - 55 °C, perform water bath heating, and keep it at a constant temperature for more than half an hour;

[0008] S2. Then, add part of polyaluminum chloride to the titanium dioxide slurry first. After ultrasonic reaction for a period of time, add part of titanium tetrachloride, and carry out ultrasonic reaction for a period of time. Then, slowly add the remaining polyaluminum chloride and titanium tetrachloride in sequence, carry out ultrasonic dispersion for 0.5 - 1 h, keep the temperature at 80 - 90 °C for 0.5 - 1 h, place it at 20 - 90 °C for static aging for 2 - 5 h, and then filter to obtain Particle 1.

[0009] S3. Mix and disperse Particle 1, dispersant, and water evenly, then add modified silica and organic solvent and mix evenly. After aging, centrifugation, washing, drying, and grinding, Particle 2 is obtained.

[0010] S4. Dissolve Particle 2 in an acid solution for a period of time to obtain hollow particles of titanium dioxide coated with porous silica.

[0011] In the present invention, first, a layer of acid - decomposable component is wrapped outside the titanium dioxide, and then a layer of silica is wrapped outside it to form a porous coating layer. Subsequently, the coated titanium dioxide particles are placed in an acidic solution, so that the acid - decomposable component in the middle layer dissolves out, and finally hollow particles of titanium dioxide coated with porous silica are formed, making the titanium dioxide have better compatibility with other components in the ink.

[0012] Specifically, in the present invention, polyaluminum chloride and titanium tetrachloride are added to the titanium dioxide slurry in sequence and are added in multiple portions respectively, so that the hydrolyzate of polyaluminum chloride mainly presents in the form of hydroxy - chloride, and the possibility of agglomeration is reduced under the ultrasonic environment, improving the dispersibility, enabling it to be uniformly coated on the surface of titanium dioxide. Then, titanium tetrachloride is added, and its hydrolysis product also presents in the form of hydroxy - chloride and can be more uniformly coated on the outer surface of the previously formed coated particles. In this way, a double - layer coating is formed. Then, the remaining polyaluminum chloride and titanium tetrachloride are added in portions, so that different - density hydroxy - chlorides are formed on the outer surface of titanium dioxide, which can make the dispersibility of titanium dioxide better, and thus can better coat the silicon film layer, making the coated titanium dioxide have better compatibility with other components in the ink. During the subsequent dissolution process in the acid solution, polyaluminum chloride and titanium tetrachloride continue to depolymerize, hydrolyze, and dissolve out, while the silicon - coated titanium dioxide is difficult to dissolve in the acid solution, and its acid dissolution rate is only a few percent, that is, after the middle layer is completely dissolved out, almost no obvious dissolution phenomenon will occur in the solution, and finally stable hollow particles of titanium dioxide coated with porous silica can be formed.

[0013] Further, in S1, carry out ultrasonic dispersion at 4000 Hz - 5000 Hz for 0.5 - 1 h, and heat in a water bath to 60 - 90 °C.

[0014] Further, in S2, 30-60% of polyaluminum chloride and 30-60% of titanium tetrachloride are added for the first time; the remaining polyaluminum chloride and titanium tetrachloride are added in at least two times.

[0015] Further, in S2, the total mass ratio of polyaluminum chloride to titanium tetrachloride is 1-2:1.

[0016] Further, in S2, each time of ultrasonic reaction, ultrasonic dispersion is carried out at 4000Hz-5000Hz for 0.5-1h.

[0017] Further, in S2, keep warm at 80-90°C for 0.5-1h, and place it at 20-90°C for static aging for 2-5h.

[0018] Further, in S3, the dispersant includes at least one of sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, water glass, sodium dialkyl sulfate, sodium dodecylbenzenesulfonate, triethylhexyl phosphate, methyl pentanol, fatty acid polyethylene glycol ester.

[0019] Further, in S3, the mass ratio of particle one, dispersant, and modified silica is 5-10:1:1-3.

[0020] Further, in S4, the acid solution can be an acidic solution such as sulfuric acid or hydrochloric acid, ultrasonic dispersion is carried out for 1-5min, and then it is dissolved at 170-180°C for 10-30min.

[0021] Further, the preparation method of the modified silica is as follows:

[0022] (1) React aniline trimer with a silane coupling agent to form a silanized aniline trimer; wherein, the mass ratio of aniline trimer to the silane coupling agent is 5-10:1;

[0023] (2) Disperse silica nanoparticles in a solvent (such as anhydrous ethanol), add trimethylchlorosilane and silanized aniline trimer after ultrasonic treatment for 15min; after reacting at 50-80°C for 15-20h, obtain the modified silica after centrifugal separation, washing, drying, and grinding.

[0024] By mixing and reacting silica with trimethylchlorosilane and silanized aniline trimer, the binding strength with silica is higher, and amino and imine groups are introduced, showing higher activity and stability. More importantly, the dispersion stability in ink is improved. Specifically, a large number of siloxane bonds, hydrogen bonds and covalent bonds are chemically bonded to the particle surface of silica. On the one hand, it can be connected to the outer layer of the particle to coat and form particle two with a silica coating, and during the subsequent acidolysis process, it can be acidolyzed and dissolved together; on the other hand, an organic coating layer can be formed on the surface of silica, increasing the distance between particles and reducing interactions such as van der Waals forces, thereby preventing particle aggregation due to steric hindrance effects; and surface charges (such as protonation of amino groups) are introduced on its surface, so that the silica particles are kept in a dispersed state due to electrostatic repulsion in the medium, improving the compatibility between silica and media such as ink solvents and binders, making it easier to disperse uniformly and improving the ink film formation quality.

[0025] Furthermore, the mass ratio of the silica nanoparticles, trimethylchlorosilane, and silanized aniline trimer is 20 - 50:2 - 5:1 - 3.

[0026] Furthermore, in step (2), centrifuge at a speed of 1000 - 2000 r / min for 10 - 30 min, and dry at a constant temperature of 50 - 100 °C for 24 - 48 h.

[0027] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0028] The present invention first wraps an easily acidolyzable component outside the titanium dioxide, and then wraps a layer of silica on its outer layer to form a porous coating layer. Subsequently, the coated titanium dioxide particles are placed in an acidic solution to dissolve the middle easily acidolyzable component, and finally form hollow particles of porous silica-coated titanium dioxide, making the coated titanium dioxide have better compatibility with the ink system. Detailed implementation manners

[0029] To make the objectives, 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. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0030] Example 1

[0031] A production method of hollow spherical titanium dioxide includes the following steps:

[0032] S1. Disperse titanium dioxide in water, ultrasonically disperse it at 4500 Hz for 0.5 h, and heat it in a water bath to 70 °C to prepare a titanium dioxide slurry with a mass fraction of 100 g / L.

[0033] Grind and disperse the calcined TiO2 particles with a Raymond mill, control the dispersion fineness so that the residue on a 600-mesh sieve is ≤ 0.5%, then add water to make a slurry, add 0.45% of sodium hexametaphosphate, and conduct secondary grinding and dispersion with a sand mill. Control the D50 of the slurry at 0.33, conduct secondary water replenishment, prepare a 100 g / L slurry, put the slurry into a water bath at 50 °C, conduct water bath heating, and keep it at a constant temperature for half an hour.

[0034] S2. Then, first add part of 60% polyaluminum chloride to the titanium dioxide slurry, ultrasonically disperse it at 4500 Hz for 0.5 h, then add 60% titanium tetrachloride, ultrasonically disperse it at 4500 Hz for 0.5 h, and then slowly add the remaining polyaluminum chloride and titanium tetrachloride in two portions in sequence, ultrasonically disperse for 0.5 h, keep it at 85 °C for 0.5 h, place it at 60 °C and let it stand for aging for 3 h, and then filter to obtain Particle One.

[0035] Mix and disperse Particle One, sodium hexametaphosphate, and water evenly, then add modified silica and anhydrous ethanol and mix evenly. Let it stand for aging at 60 °C for 3 h, centrifuge at a speed of 1500 r / min for 20 min, wash twice with distilled water, dry at a constant temperature of 80 °C for 24 h, and then grind to obtain Particle Two. Among them, the mass ratio of Particle One, dispersant, and modified silica is 8:1:2.

[0036] The preparation method of modified silica is as follows:

[0037] (1) Mix aniline trimer and KH-570 silane coupling agent in a mass ratio of 8:1 and react to form silanized aniline trimer.

[0038] (2) Disperse silica nanoparticles in anhydrous ethanol, add trimethylchlorosilane and silanized aniline trimer after ultrasonic treatment for 15 min. After reacting at 70 °C for 15 h, centrifuge at a speed of 1000 r / min for 30 min, wash twice with distilled water, and dry at a constant temperature of 90 °C for 24 h to obtain modified silica.

[0039] S4. Place Particle Two in 98% sulfuric acid and ultrasonically disperse it for 3 min, then dissolve it at 175 °C for 20 min to obtain hollow particles of porous silica-coated titanium dioxide.

[0040] Example 2

[0041] The difference between this example and Example 1 is that a production method of hollow spherical titanium dioxide includes the following steps:

[0042] S2. Then, add a part of 50% polyaluminum chloride to the titanium dioxide slurry, ultrasonically disperse it at 4000 Hz for 1 h, then add 40% titanium tetrachloride, ultrasonically disperse it at 5000 Hz for 0.5 h, and then slowly add the remaining polyaluminum chloride and titanium tetrachloride in two batches successively, ultrasonically disperse for 0.5 h, keep it warm at 90 °C for 1 h, place it at 50 °C for static aging for 4 h, and then filter to obtain Particle 1;

[0043] S3. Mix and disperse Particle 1, sodium dodecylbenzenesulfonate, and water evenly, then add modified silica and anhydrous ethanol and mix evenly. Let it stand and age at 50 °C for 2 h, centrifuge at a speed of 1300 r / min for 30 min, wash twice with distilled water, and dry at a constant temperature of 70 °C for 24 h, and then obtain Particle 2 after grinding. Among them, the mass ratio of Particle 1, sodium dodecylbenzenesulfonate, and modified silica is 6:1:3;

[0044] S4. Ultrasonically disperse Particle 2 in 98% sulfuric acid for 2 min, and then dissolve it at 180 °C for 10 min to obtain hollow particles of titanium dioxide coated with porous silica.

[0045] Example 3

[0046] The difference between this example and Example 1 lies in a method for producing hollow spherical titanium dioxide, which includes the following steps:

[0047] S2. Then, add a part of 40% polyaluminum chloride to the titanium dioxide slurry, ultrasonically disperse it at 5000 Hz for 0.5 h, then add 60% titanium tetrachloride, ultrasonically disperse it at 4000 Hz for 1 h, and then slowly add the remaining polyaluminum chloride and titanium tetrachloride in three batches successively, ultrasonically disperse for 0.5 h, keep it warm at 90 °C for 0.5 h, place it at 70 °C for static aging for 4 h, and then filter to obtain Particle 1;

[0048] S3. Mix and disperse Particle 1, sodium tripolyphosphate, and water evenly, then add modified silica and organic solvent and mix evenly. Let it stand and age at 60 °C for 1 h, centrifuge at a speed of 1500 r / min for 30 min, wash twice with distilled water, and dry at a constant temperature of 70 °C for 24 h, and then obtain Particle 2 after grinding. Among them, the mass ratio of Particle 1, dispersant, and modified silica is 5 - 10:1:1 - 3;

[0049] S4. Ultrasonically disperse Particle 2 in 98% sulfuric acid for 1 - 5 min, and then dissolve it at 170 °C for 30 min to obtain hollow particles of titanium dioxide coated with porous silica.

[0050] Comparative Example 1

[0051] The difference between this comparative example and Example 1 is that there is no S2.

[0052] Comparative Example 2

[0053] The difference between this comparative example and Example 1 is that in S2, only polyaluminium chloride is added and added at one time.

[0054] Comparative Example 3

[0055] The difference between this comparative example and Example 1 is that in S3, the silicon dioxide is not modified, that is, ordinary silicon dioxide is used.

[0056] Experimental Example 1

[0057] The acid solubility and compatibility of the titanium dioxide particles prepared in each embodiment and comparative example in ink were tested. The results are shown in Table 1.

[0058] Table 1

[0059] Acid dissolution rate (%) Compatibility Example 1 2 Uniform dispersion Example 2 2 Uniform dispersion Example 3 2.5 Uniform dispersion Comparative Example 1 8 Agglomeration Comparative Example 2 5 Agglomeration Comparative Example 3 37 Average dispersion

[0060] As shown in Table 1, the dense silicon-coated titanium dioxide formed by modified silicon dioxide in the present invention is difficult to dissolve in concentrated sulfuric acid, and its acid solubility is only 2%; and it exhibits excellent dispersion uniformity and good compatibility with the ink system;

[0061] In Comparative Example 3, the titanium dioxide powder with a loose coating formed only by ordinary silica has a higher acid solubility rate of nearly 40%, but its dispersibility is moderate and no obvious agglomeration occurs. This is mainly because the intermediate layer dissolves during the acid dissolution process to form a hollow coating structure. Although Comparative Examples 1-2 all have a dense silicon coating formed by modified silica, Comparative Example 1 has no intermediate layer, that is, the titanium dioxide powder is only coated with a modified silicon layer. In this way, during the acid dissolution process, since there is no intermediate hollow layer, although the effect on the acid solubility rate of the product is not significant, and only a slightly higher acid solubility rate is shown, it has a greater impact on the compatibility of the product in the ink. This may be mainly because the hollow structure in the middle and the silicon coating structure of the outer layer make the product more uniformly dispersed in the ink with other substances such as solvents.

[0062] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A production method of hollow spherical titanium dioxide, characterized in that, It includes the following steps: S1. Subject the calcined TiO2 particles to primary depolymerization, then add a dispersant, grind and disperse, and heat in a water bath to prepare a titanium dioxide slurry with a mass fraction of 40 - 200 g / L; S2. First add part of the polyaluminum chloride to the titanium dioxide slurry, react ultrasonically for a period of time, then add part of the titanium tetrachloride and react ultrasonically for a period of time, and then slowly add the remaining polyaluminum chloride and titanium tetrachloride in sequence. After ultrasonic dispersion, heat preservation, and aging, filter to obtain Particle One; S3. Mix and disperse Particle One, the dispersant, and water evenly, then add the modified silica and an organic solvent and mix evenly. After aging, centrifugation, washing, drying, and grinding, obtain Particle Two; S4. Place Particle Two in an acid solution and dissolve for a period of time to obtain hollow particles of titanium dioxide coated with porous silica.

2. The production method of the hollow spherical titanium dioxide according to claim 1, characterized in that In S2, 30 - 60% of the polyaluminum chloride and 30 - 60% of the titanium tetrachloride are added for the first time; the remaining polyaluminum chloride and titanium tetrachloride are added in at least two times.

3. The production method of hollow spherical titanium dioxide according to claim 1, characterized in that, In S2, the total mass ratio of polyaluminum chloride to titanium tetrachloride is 1 - 2:

1.

4. The production method of the hollow spherical titanium dioxide according to claim 1, characterized in that, In S3, the dispersant includes at least one of sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, water glass, sodium dialkyl sulfate, sodium dodecylbenzenesulfonate, triethylhexyl phosphate, methyl amyl alcohol, and fatty acid polyethylene glycol ester.

5. The production method of the hollow spherical titanium dioxide according to claim 1, characterized in that, In S3, the mass ratio of Particle One, the dispersant, to the modified silica is 5 - 10:1:1 - 3.

6. The production method of the hollow spherical titanium dioxide according to claim 1, characterized in that, In S4, the acid solution is sulfuric acid or hydrochloric acid. After ultrasonic dispersion for 1 - 5 min, dissolve at 170 - 180 °C for 10 - 30 min.

7. The production method of the hollow spherical titanium dioxide according to claim 1, characterized in that, The preparation method of the modified silica is as follows: (1) React aniline trimer with a silane coupling agent to form a silylated aniline trimer; (2) Disperse the silica nanoparticles in a solvent, add trimethylchlorosilane and the silylated aniline trimer after ultrasonic treatment and react for a period of time, and then obtain the modified silica after centrifugal separation, washing, drying, and grinding.

8. The production method of the hollow spherical titanium dioxide according to claim 7, characterized in that, The mass ratio of the silica nanoparticles, trimethylchlorosilane, to the silylated aniline trimer is 20 - 50:2 - 5:1 - 3.

9. The production method of the hollow spherical titanium dioxide according to claim 7, characterized in that, In step (2), centrifuge at a speed of 1000 - 2000 r / min for 10 - 30 min, and dry at a constant temperature of 50 - 100 °C for 24 - 48 h.

10. A hollow spherical titanium dioxide, characterized in that, Prepared by the production method described in any one of claims 1 - 9.