Development and application of pigment-grade high-whiteness zinc sulfide

Abstract

The invention discloses development and application of pigment-grade high-whiteness zinc sulfide. The preparation method of the pigment-grade zinc sulfide comprises the following steps: S1, purifying zinc sulfate through ion exchange resin, and activating sodium thiosulfate to form active S2-, S2, reacting the purified zinc sulfate obtained in the step S1 with the active S2-in an electromagnetic field enhanced tubular reactor to generate zinc sulfide powder, s3, the zinc sulfide powder generated in the step S2 is coated with a coating material, S4, the coated zinc sulfide in the step S3 is placed in a fluidized bed to be dried, magnesium stearate is sprayed on the coated zinc sulfide to obtain the pigment-grade zinc sulfide, the coating material is a mixture of polyhedral oligomeric silsesquioxane and an h-BN-coated Si hybrid material, and the h-BN-coated Si hybrid material is a mixture of polyhedral oligomeric silsesquioxane and the h-BN-coated Si hybrid material. The addition amount of the coating material is 5-9 wt% of the zinc sulfide. The pigment-level zinc sulfide prepared by the method has the advantages of high whiteness, uniform particle size distribution and excellent humidity and heat resistance, and the adopted preparation process is environment-friendly, high in economic benefit and suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic functional materials, and particularly to the development and application of a pigment-grade high-whiteness zinc sulfide. Background Art

[0002] As a white pigment with unique properties, zinc sulfide not only has a low Mohs hardness but also has almost no photocatalytic effect, which gives it significant advantages in certain application fields. For example, it can be an ideal substitute for titanium dioxide to improve the toughness and aging resistance of materials such as polypropylene, while effectively avoiding problems such as material damage that may be caused by the photocatalytic action of titanium dioxide.

[0003] With the continuous progress in the field of materials science, the demand for high-performance and high-quality pigments in various industries is also continuously increasing. However, there are still some problems to be solved with the current zinc sulfide products on the market, which to a certain extent limit its application as a high-quality pigment. For example, due to excessive impurity content or immature production processes, some zinc sulfide products have insufficient whiteness, affecting their basic properties as pigments. In addition, problems such as larger particle sizes of zinc sulfide particles and easy agglomeration also result in poor dispersibility in materials such as plastics, thereby reducing its application effect in these materials. And zinc sulfide is prone to chemical reactions under humid and hot conditions, affecting its storage and transportation, greatly limiting the wide application of zinc sulfide.

[0004] The choice of raw materials also affects the quality of zinc sulfide. For example, although sodium sulfide, as a commonly used sulfur source, has a relatively low price, it has many disadvantages, such as having an odor, high impurity content, poor color, and complex purification processes, which bring inconvenience and additional costs to actual production. For other sulfur sources, such as hydrogen sulfide, due to its highly toxic nature, there are defects in transportation and storage; organic sulfur compounds are limited in their application in large-scale industrial production due to their high prices.

[0005] Similarly, different preparation processes used also affect the quality of zinc sulfide. The zinc sulfide produced by the existing direct reaction process of sodium sulfide and zinc sulfate still has a large gap from the requirements of high-quality pigment-grade zinc sulfide in terms of key performance indicators such as whiteness and particle size. This indicates that there is still much room for improvement in the current production process and further optimization and innovation are needed.

[0006] In summary, in order to better meet the urgent needs of multiple fields such as plastics, coatings, and rubber for high-performance white pigments, and further improve the performance and quality of related products, it is particularly important to develop zinc sulfide pigments with high whiteness, controllable particle size, and stable storage and their production processes. This will not only contribute to the technological progress of the pigment industry itself but also have a positive impact on the product upgrade and performance improvement of downstream application fields. Summary of the Invention

[0007] In view of the defects in the prior art, the present invention proposes the development and application of a pigment-grade high-white zinc sulfide.

[0008] The present invention provides a method for preparing a pigment-grade zinc sulfide, comprising the following steps:

[0009] S1: Purify zinc sulfate through an ion exchange resin, and simultaneously activate sodium thiosulfate to form active S 2- ;

[0010] S2: React the purified zinc sulfate obtained in step S1 with active S 2- in a tubular reactor strengthened by an electromagnetic field to generate zinc sulfide powder;

[0011] S3: Coating the zinc sulfide powder generated in step S2 with a coating material;

[0012] S4: Place the coated zinc sulfide in step S3 in a fluidized bed for drying and spray magnesium stearate to obtain the pigment-grade zinc sulfide;

[0013] Wherein, the coating material is a mixture of cage-type polyhedral oligomeric silsesquioxane (F-POSS) and hexagonal boron nitride@silicon hybrid material (h-BN@Si); the addition amount of the coating material is 5wt%-9wt% of zinc sulfide, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt%.

[0014] Purifying zinc sulfate through an ion exchange resin can effectively remove impurities. Specific functional groups in the ion exchange resin can undergo an ion exchange reaction with metal ions in the solution, selectively adsorb metal ions in the solution, and thereby improve the purity of the reactants. At the same time, activate sodium thiosulfate, and the activation process can increase S in sodium thiosulfate 2-The activity of the reactant molecules is increased, making it easier to participate in chemical reactions. At the same time, activation can also reduce the occurrence of subsequent side reactions, improve the selectivity of the reaction and the purity of the product. The electromagnetic field can enhance the turbulence and mixing effects of the fluid, so that the reactants are evenly dispersed and collided during the reaction process, avoiding the agglomeration caused by the excessive concentration of local reactants. The raw materials are more fully mixed and dispersed under the action of the electromagnetic field, which is conducive to the generation of zinc sulfide powder with uniform particle size and good dispersibility, and greatly improves the particle agglomeration phenomenon. In addition, the electromagnetic field can also accelerate the movement of the reactant molecules, increase the collision frequency between molecules, improve the activity of the reactant molecules, and participate in the reaction more quickly and form a uniform product, further reduce the aggregation of unreacted or insufficiently reacted reactants to form agglomerates, and significantly improve the reaction rate while improving the selectivity of the reaction, reducing the occurrence of side reactions and improving the purity of the product. The inventors also found that the zinc sulfide powder can be coated with a mixture of cage-type polysilsesquioxane and h-BN@Si hybrid material to give the zinc sulfide powder a variety of functional properties. The intermolecular forces between h-BN sheets and F-POSS can form a stable coating structure and enhance the adhesion of the coating. The perfluorinated chains of F-POSS give the zinc sulfide surface a negative charge, inhibiting particle agglomeration. Its unique cage structure can also work together with the layer structure of h-BN to further prevent the agglomeration of zinc sulfide particles, making them more evenly dispersed in applications. In addition, the cage-type polysilsesquioxane and h-BN@Si hybrid material can also simultaneously form a multi-scale light scattering interface on the zinc sulfide surface, enhancing the reflectivity of visible light, reducing the absorptivity, and significantly improving the whiteness of zinc sulfide.

[0015] Further, the mass ratio of the cage-type polysilsesquioxane to the h-BN@Si hybrid material is (1-2): 1, preferably (1.5-2): 1. The nano cage structure of F-POSS can be embedded in the h-BN@Si interlaminar gap and significantly reduce the porosity, forming a three-dimensional dense barrier network to block water oxygen molecules. When the amount of F-POSS added is too little, the pores will become more and then reduce the storage stability of the coated zinc sulfide molecules in a humid environment, and the short-wavelength reflectivity of the zinc sulfide surface will decrease, affecting the whiteness of the product. When the amount of F-POSS added is too much, it will be over-stacked, destroying the horizontal arrangement of h-BN@Si in the coating layer, which will also affect the barrier efficiency, resulting in reduced storage stability, and increase the product manufacturing cost.

[0016] Furthermore, the reaction in step S2 includes a preheating section, a reaction section and a cooling section;

[0017] The temperature of the preheating section is 90-110°C;

[0018] The temperature of the reaction section is 130-165°C;

[0019] The temperature of the cooling section is 165 - 80 °C.

[0020] Through the design of gradient temperature, nucleation and growth can be controlled in stages. Controlling the temperature of the preheating section at 90 - 110 °C can promote uniform nucleation under low temperature and low supersaturation. At the same time, under the drive of the magnetic field, charged ions can migrate directionally, avoiding local concentration gradients and ensuring uniform distribution of nucleation sites; when the temperature of the reaction section is 130 - 165 °C, the diffusion rate of reactants increases, and at the same time, the magnetic field drives the particles to be arranged directionally along the magnetic force lines, reducing abnormal agglomeration caused by random collisions; the combined effect of these measures can make the particle size of zinc sulfide particles uniform and controllable.

[0021] Furthermore, in step S1, a continuous ultraviolet reactor is used to activate sodium thiosulfate;

[0022] The wavelength of the ultraviolet reactor is 254 nm, the light intensity is 14 - 17 mW / cm 2 , and the residence time is 18 - 25 min.

[0023] Furthermore, the ion exchange resin in step S1 is selected from any one of Lewatit TP260 resin, IRC - 748 resin, T - IRR resin, preferably IRC - 748 resin.

[0024] Furthermore, the preparation method of the h - BN@Si hybrid material includes the following steps:

[0025] Put hexagonal boron nitride powder into a CVD reactor, then introduce SiH4 and N2, and deposit at 620 - 700 °C for 20 - 35 min to obtain hexagonal boron nitride@silicon hybrid material, and the thickness of the Si coating layer is 1 - 3 nm;

[0026] The particle size D50 of the powder is 10 - 50 nm, and the volume ratio of SiH4 to N2 is 1:(1.5 - 9).

[0027] Furthermore, the flow rate of SiH4 is 0.2 - 0.5 L / min, and the flow rate of N2 is 1 - 4 L / min.

[0028] Furthermore, the coating in step S3 specifically includes the following steps:

[0029] The cage-shaped polyhedral oligomeric silsesquioxane and the h-BN@Si hybrid material are added to a solvent according to a mass ratio to prepare a mixed coating solution. Then, the zinc sulfide powder prepared in step S2 is mixed with the coating solution at a mass ratio of 1:(7-10). Selecting an appropriate solid-liquid ratio can ensure that the coating solution fully wets the particle surface, forming a uniform pre-adsorption layer, and at the same time can avoid excessive local concentration of the coating solution, causing particle agglomeration. Then, it is ultrasonically dispersed for 1-1.5 h. Ultrasonic treatment mainly destroys the initially formed aggregates and promotes the directional adsorption of the coating material on the surface of zinc sulfide, ensuring that the coating layer covers the surface of zinc sulfide. Finally, the solvent is recovered by vacuum distillation at 58-75 °C. Vacuum distillation can further induce the molecular self-assembly of the coating material to form a denser cross-linked network, that is, zinc sulfide with a stable coating is obtained.

[0030] The solvent is obtained by mixing water and ethanol at a volume ratio of 1:(2-3).

[0031] Further, the particle size of the cage-shaped polyhedral oligomeric silsesquioxane in step S3 is 2-5 nm.

[0032] Further, in step S2, the magnetic field strength is 0.3-0.5 T and the frequency is 100-150 Hz.

[0033] Further, the ultrasonic frequency in step S3 is 40-50 Hz.

[0034] Further, in step S4, the spraying amount of magnesium stearate is 0.15-0.3 wt% of the zinc sulfate after coating, and the atomization pressure is 0.25-0.35 MPa, where the temperature in the first zone is 78-85 °C, the temperature in the second zone is 118-125 °C, and the temperature in the third zone is 58-65 °C.

[0035] The present invention also provides pigment-grade zinc sulfide prepared by the above preparation method, and the whiteness of the zinc sulfide is ≥96.

[0036] The present invention also provides the application of the pigment-grade zinc sulfide as a pigment in paints, coatings and plastic products.

[0037] In summary, compared with the prior art, the present invention has achieved the following technical effects:

[0038] (1) The pigment-grade zinc sulfide of the present invention has high whiteness and can be used as a pigment to replace titanium dioxide.

[0039] (2) The pigment-grade zinc sulfide of the present invention also has anti-humidity and heat resistance and can be stably stored in a humid and hot environment.

[0040] (3) The pigment-grade zinc sulfide of the present invention has uniform and controllable particle size and can be quickly dispersed during application.

[0041] (4) The raw materials used in the pigment-grade zinc sulfide of the present invention are friendly to the environment and human body, and can reduce costs, being suitable for large-scale production applications.

[0042] (5) The preparation process of the pigment-grade zinc sulfide provided by the present invention uses a single tubular reactor for zone temperature control and does not require intermediate transfer, which can avoid problems such as particle agglomeration or contamination caused by equipment switching. Detailed implementation manners

[0043] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] Embodiment

[0045] The present invention will be further described below in conjunction with specific examples and comparative examples. The following specific examples are all preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following examples, especially not limited to the models of the component raw materials used in the following specific examples.

[0046] I. Sources of raw materials for examples and comparative examples

[0047] Unless otherwise specified, the raw materials of the examples and comparative examples of the present invention are all commercially available;

[0048] The h-BN@Si hybrid material used in the present invention is self-made, and the preparation method is as follows: Place 100 g of h-BN powder with a particle size D50 of 25 nm in a CVD reactor, and then introduce SiH4 and N2 respectively. Control the gas flow rates of SiH4 and N2 to be 0.2 L / min and 1.2 L / min respectively, and deposit for 25 min at 680 °C to obtain the h-BN@Si hybrid material, and the thickness of the Si coating layer is 1.3 nm.

[0049] II. Test methods for various performances

[0050] (1) Whiteness value test: The whiteness value of the sample is tested according to the relevant standards of GB / T 4104-2017, and pure magnesium oxide is selected as the reference.

[0051] (2) Particle monodispersity (PDI) test: The sample was measured using a dynamic light scattering instrument, and deionized water containing 10 mM KNO3 was used as the solvent. PDI (polydispersity index) is an important parameter to measure the uniformity of particle distribution, which reflects the deviation between the actual particle size distribution and the ideal monodisperse system. The value range of PDI is usually between 0 and 1. The smaller the PDI value, the more uniform the particle size distribution.

[0052] (3) Damp heat resistance test: The zinc sulfide sample was stored at 85 °C / 85% RH for 28 days to simulate the influence of long-term damp heat environment, and the weight gain rate and the change of whiteness value of zinc sulfide were tested. The weight gain rate was: (final weight - initial weight) / initial weight × 100%, and the change of whiteness value was: initial whiteness value - final whiteness value.

[0053] Example 1

[0054] The preparation method of the pigment-grade zinc sulfide in this example includes the following steps:

[0055] S1: Weigh 2 kg of zinc sulfate and add it to 1 m 3 of deionized water, and then control the zinc sulfate solution to pass through 3 IRC-748 ion exchange resin for purification at a flow rate of 3 m / h. At the same time, dissolve 1.5 kg of sodium thiosulfate in 1 m 3 of deionized water, and activate the solution in a UV reactor with a light intensity of 15 mW / cm 2 for 25 min to form active S 2- ;

[0056] S2: React the purified zinc sulfate obtained in step S1 with active S 2- in a tube reactor strengthened by electromagnetic field. Among them, the magnetic field intensity is 0.3 T, the frequency is 100 Hz, the temperature of the preheating section is set at 98 - 105 °C, the reaction section temperature is 148 - 155 °C, and the cooling section temperature is 155 - 85 °C;

[0057] S3: Weigh 40 g of cage-type polyhedral oligomeric silsesquioxane with a particle size D50 of 4 nm and 20 g of h-BN@Si hybrid material, add them to 8 kg of solvent to prepare a mixed coating solution (the solvent is prepared by mixing ethanol and water at a volume ratio of 2.5:1), then weigh 1 kg of the zinc sulfide powder prepared in step S2 and mix it with the coating solution, ultrasonically disperse it at 40 kHz for 1.5 h, and finally carry out vacuum distillation at 72 °C to recover the solvent, thus obtaining the coated zinc sulfide;

[0058] S4: Place the coated zinc sulfide obtained in step S3 in a fluidized bed for drying and spray 0.2 wt% magnesium stearate (atomization pressure 0.3 MPa), where the temperature of zone 1 is set to 80 °C, the temperature of zone 2 is 120 °C, and the temperature of zone 3 is 60 °C, thus obtaining pigment-grade zinc sulfide with a D50 particle size of 120 nm.

[0059] Example 2

[0060] The preparation method of the pigment-grade zinc sulfide in this example includes the following steps:

[0061] S1: Weigh 2.3 kg of zinc sulfate and add it to 1 m 3 of deionized water, and then control the zinc sulfate solution to pass through 3 IRC-748 ion exchange resin at a flow rate of 2.5 m / h for purification. At the same time, dissolve 1.7 kg of sodium thiosulfate in 1 m 3 of deionized water, and subject the solution to activation treatment in an ultraviolet reactor with a light intensity of 17 mW / cm 2 for 20 min to form active S 2- ;

[0062] S2: React the purified zinc sulfate obtained in step S1 with active S 2- in an electromagnetic field-strengthened tubular reactor, where the magnetic field strength is 0.4 T, the frequency is 120 Hz, the temperature of the preheating section is set to 92 - 99 °C, the temperature of the reaction section is 135 - 145 °C, and the temperature of the cooling section is 145 - 82 °C;

[0063] S3: Weigh 53 g of cage-type polyhedral oligomeric silsesquioxane with a particle size of 3 nm and 27 g of h-BN@Si hybrid material, add them to 9.5 kg of solvent to prepare a mixed coating solution (the solvent is prepared from ethanol and water in a volume ratio of 3:1), then weigh 1 kg of the zinc sulfide powder prepared in step S2 and mix it with the coating solution, ultrasonically disperse it at 50 kHz for 1 h, and finally carry out vacuum distillation at 62 °C to recover the solvent, thus obtaining the coated zinc sulfide;

[0064] S4: Place the coated zinc sulfide obtained in step S3 in a fluidized bed for drying and spray 0.2 wt% magnesium stearate (atomization pressure 0.3 MPa), where the temperature of zone 1 is set to 80 °C, the temperature of zone 2 is 120 °C, and the temperature of zone 3 is 60 °C, thus obtaining pigment-grade zinc sulfide with a D50 particle size of 122 nm.

[0065] Example 3

[0066] The preparation method of the pigment-grade zinc sulfide in this example includes the following steps:

[0067] S1: Weigh 2 kg of zinc sulfate and add it to 1 m 3in deionized water, and then controlling the zinc sulfate solution to pass through 3 at a flow rate of 3 m / h through the IRC-748 ion exchange resin for purification. At the same time, dissolve 1.5 kg of sodium thiosulfate in 1 m 3 of deionized water, and activate the solution in a UV reactor with a light intensity of 15 mW / cm 2 for 25 min to form active S 2- ;

[0068] S2: React the purified zinc sulfate obtained in step S1 with active S 2- in a tube reactor enhanced by an electromagnetic field. Among them, the magnetic field intensity is 0.3 T, the frequency is 150 Hz, the temperature of the preheating section is set at 98 - 105 °C, the temperature of the reaction section is 158 - 165 °C, and the temperature of the cooling section is 165 - 85 °C;

[0069] S3: Weigh 47 g of cage-type polyhedral oligomeric silsesquioxane with a particle size of 3 nm and 23 g of h-BN@Si hybrid material, add them to 8 kg of solvent to prepare a mixed coating solution (the solvent is prepared from ethanol and water according to a volume ratio of 2:1), then weigh 1 kg of the zinc sulfide powder prepared in step S2 and mix it with the coating solution, disperse it by ultrasonic wave at 40 kHz for 1.2 h, and finally carry out vacuum distillation at 65 °C to recover the solvent, thus obtaining the coated zinc sulfide;

[0070] S4: Place the coated zinc sulfide in step S3 in a fluidized bed for drying and spray 0.3 wt% of magnesium stearate (atomization pressure 0.35 MPa), where the temperature of the first zone is set at 82 °C, the temperature of the second zone is 125 °C, and the temperature of the third zone is 63 °C, thus obtaining pigment-grade zinc sulfide with a particle size D50 of 118 nm.

[0071] Example 4

[0072] The difference between Example 4 and Example 1 is that the ion exchange resin used is T-IRR resin, and the particle size D50 of the obtained pigment-grade zinc sulfide is 121 nm.

[0073] Example 5

[0074] The difference between Example 5 and Example 1 is that in step S3, the addition amounts of both the cage-type polyhedral oligomeric silsesquioxane and the h-BN@Si hybrid material are 30 g, that is, the mass ratio of the cage-type polyhedral oligomeric silsesquioxane to the h-BN@Si hybrid material is 1:1, and the particle size D50 of the obtained pigment-grade zinc sulfide is 120 nm.

[0075] Example 6

[0076] Example 6 is different from Example 1 in that the addition amounts of cage-like polyhedral oligomeric silsesquioxane and h-BN@Si hybrid material in step S3 are 36 g and 24 g respectively, that is, the mass ratio of cage-like polyhedral oligomeric silsesquioxane to h-BN@Si hybrid material is 1.5:1, and the D50 of the pigment-grade zinc sulfide prepared is 122 nm.

[0077] Comparative Example 1

[0078] Comparative Example 1 is different from Example 1 in that the addition amounts of cage-like polyhedral oligomeric silsesquioxane and h-BN@Si hybrid material in step S3 are 14 g and 46 g respectively, that is, the mass ratio of cage-like polyhedral oligomeric silsesquioxane to h-BN@Si hybrid material is 0.3:1, and the D50 of the pigment-grade zinc sulfide prepared is 125 nm.

[0079] Comparative Example 2

[0080] Comparative Example 2 is different from Example 1 in that the addition amounts of cage-like polyhedral oligomeric silsesquioxane and h-BN@Si hybrid material in step S3 are 48 g and 12 g respectively, that is, the mass ratio of cage-like polyhedral oligomeric silsesquioxane to h-BN@Si hybrid material is 4:1, and the D50 of the pigment-grade zinc sulfide prepared is 158 nm.

[0081] Comparative Example 3

[0082] Comparative Example 3 is different from Example 1 in that only 60 g of cage-like polyhedral oligomeric silsesquioxane is added in step S3, and the D50 of the pigment-grade zinc sulfide prepared is 167 nm.

[0083] Comparative Example 4

[0084] Comparative Example 4 is different from Example 1 in that only 60 g of h-BN@Si hybrid material is added in step S3, and the D50 of the pigment-grade zinc sulfide prepared is 133 nm.

[0085] Comparative Example 5

[0086] Comparative Example 5 is different from Example 1 in that the tubular reactor is not electromagnetically strengthened in step S2, and the D50 of the pigment-grade zinc sulfide prepared is 176 nm.

[0087] Table 1. Performance test results of examples and comparative examples

[0088]

[0089] Comparative Examples 1-5 were each compared with Example 1 with a single variable. In Comparative Examples 1-2, the compounding mass ratio of cage-like polyhedral oligomeric silsesquioxane and h-BN@Si hybrid material was not within the range of (1-2):1. In Comparative Example 1, too little cage-like polyhedral oligomeric silsesquioxane was added, which could not stably cooperate with the h-BN@Si hybrid material, resulting in an increase in particle gaps and local agglomeration, thus affecting the particle size distribution. At the same time, the whiteness value decreased, and the moisture isolation performance also decreased to a certain extent. In Comparative Example 2, too much cage-like polyhedral oligomeric silsesquioxane was added, also resulting in a non-uniform particle size distribution and a decrease in whiteness and anti-humid heat performance. In Comparative Examples 3-4, only one coating material was added, making it difficult to significantly improve the whiteness value, particle size uniformity, and anti-humid heat performance of zinc sulfide. In Comparative Example 5, the tubular reactor was not enhanced by electromagnetic fields, reducing the mixing and mass transfer effects of the reactants, resulting in uneven growth rates of zinc sulfide particles and easy agglomeration, leading to a wider particle size distribution and a decrease in whiteness. Moreover, the physical barrier effect weakened, and moisture and oxygen were more likely to invade, thus reducing its anti-humid heat performance.

[0090] Based on the test data of the whiteness value, particle size distribution in Table 1, and the weight gain rate and change in whiteness value of the prepared zinc sulfide after being stored in a humid and hot environment of 85°C / 85% RH for 28 days, the pigment-grade zinc sulfide prepared by the preparation methods of Examples 1-6 can maintain a uniform particle size distribution and excellent anti-humid heat performance while achieving a high whiteness (higher than 96%), meeting the high requirements for dispersion and storage in applications. It has obvious advantages compared with the comparative examples and can effectively meet the high standards of customers and the market.

[0091] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of pigment-grade zinc sulfide, characterized in that, It includes the following steps: S1: Purify zinc sulfate through an ion exchange resin, and simultaneously activate sodium thiosulfate to form active sulfur S 2- ; S2: React the purified zinc sulfate obtained in step S1 with active sulfur 2- in an electromagnetic field-enhanced tubular reactor to produce zinc sulfide powder; S3: Coating the zinc sulfide powder generated in step S2 with a coating material; S4: Placing the coated zinc sulfide in step S3 in a fluidized bed for drying and spraying magnesium stearate to obtain pigment-grade zinc sulfide; Among them, the coating material is a mixture of cage-type polyhedral oligomeric silsesquioxane and hexagonal boron nitride@silicon hybrid material; the addition amount of the coating material is 5wt%-9wt% of zinc sulfide.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the cage-type polyhedral oligomeric silsesquioxane to the hexagonal boron nitride@silicon hybrid material is (1-2):

1.

3. The preparation method according to claim 1, characterized in that, The reaction in step S2 includes a preheating section, a reaction section, and a cooling section; The temperature of the preheating section is 90-110°C; The temperature of the reaction section is 130-165°C; The temperature of the cooling section is 165-80°C.

4. The preparation method according to claim 1, characterized in that, In step S1, a continuous ultraviolet reactor is used to activate sodium thiosulfate; The light intensity of the ultraviolet reactor is 13-17 mW / cm 2 , and the residence time is 18-25 min.

5. The preparation method according to claim 1, characterized in that, The ion exchange resin in the step S1 is selected from any one of Lewatit TP260 resin, IRC-748 resin, and T-IRR resin.

6. The preparation method according to claim 1, characterized in that, The preparation method of the hexagonal boron nitride@silicon hybrid material includes the following steps: Placing hexagonal boron nitride powder in a CVD reactor, then introducing SiH4 and N2, and depositing for 20-35 minutes at 620-700°C to obtain the hexagonal boron nitride@silicon hybrid material, and the thickness of the Si coating layer is 1-3 nm; The particle size D50 of the powder is 10-50 nm, and the volume ratio of SiH4 to N2 is 1:(1.5-9).

7. The preparation method according to claim 1, characterized in that, The coating in step S3 specifically includes the following steps: Mixing the cage-type polyhedral oligomeric silsesquioxane and the hexagonal boron nitride@silicon hybrid material according to the mass ratio in a solvent to prepare a mixed coating solution, then mixing the zinc sulfide powder prepared in step S2 with the coating solution according to the mass ratio of 1:(7-10), ultrasonically dispersing for 1-1.5 h, and finally carrying out vacuum distillation at 58-75°C to recover the solvent to obtain the coated zinc sulfide; The solvent is obtained by mixing water and ethanol according to the volume ratio of 1:(2-3).

8. The preparation method according to claim 1, characterized in that, In step S2, the magnetic field strength is 0.3-0.5 T and the frequency is 100-150 Hz.

9. The pigment-grade zinc sulfide prepared by the preparation method according to any one of claims 1-8, characterized in that, The whiteness of the zinc sulfide is ≥96.

10. Application of the pigment-grade zinc sulfide according to claim 9 as a pigment in paints, coatings, and plastic products.

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