Hydrophobic silicon dioxide as well as preparation method and application thereof in delustering agent

Abstract

The hydrophobic silicon dioxide comprises porous silicon dioxide particles and fibrous silicon dioxide, the fibrous silicon dioxide is uniformly loaded on the surfaces of the porous silicon dioxide particles to form a fibrous shell layer, so that the hydrophobic silicon dioxide is in a sea urchin shape, and the surface of the fibrous silicon dioxide contains epoxy groups. The invention also discloses a preparation method of the hydrophobic silicon dioxide, which comprises the following steps: uniformly dispersing the porous silicon dioxide in a solution A, then adding an organic solvent and a silane coupling agent containing an epoxy group, uniformly mixing, reacting, and carrying out solid-liquid separation to obtain the hydrophobic silicon dioxide. The invention also discloses application of the hydrophobic silicon dioxide in a delustering agent. The hydrophobic silicon dioxide disclosed by the invention has good matting property, hydrophobicity and dispersity.

Description

Technical Field

[0001] The invention relates to the technical field of matting agents, and in particular to hydrophobic silicon dioxide and a preparation method thereof, and application of the hydrophobic silicon dioxide in matting agents. Background Art

[0002] Matting materials refer to a type of additive that can eliminate the gloss of the surface of the material to which it is applied, making the surface of the material present a matte or matte effect. At present, matting materials are mainly used in the fields of coatings, leather, chemical fibers, etc. The matting surface is different from the high-gloss effect of the mirror surface, giving people a high-end and low-key aesthetic feeling. At the same time, matting materials can also reduce the reflection of light on the surface of the material, reduce the stimulation of light to the human eye, and mask some surface defects to achieve a smooth visual effect.

[0003] Silicon dioxide is the most widely used inorganic matting material, with advantages such as good transparency and high matting efficiency. However, the surface of silicon dioxide contains a large number of hydroxyl groups and has high surface energy. It is easy to agglomerate during use, making it difficult to disperse in the paint, affecting the fluidity of the paint; and the matting performance of existing silicon dioxide also needs to be further improved. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a hydrophobic silica and a preparation method thereof, and application in a matting agent. The hydrophobic silica of the present invention has good matting, hydrophobicity and dispersibility, and expands the application scope of the matting agent.

[0005] The invention provides a hydrophobic silica, comprising: porous silica particles and fibrous silica, wherein the fibrous silica is uniformly loaded on the surface of the porous silica particles to form a fibrous shell layer, so that the hydrophobic silica is sea urchin-shaped, and the surface of the fibrous silica contains epoxy groups.

[0006] Preferably, the particle size of the porous silica is 4-6 μm.

[0007] Preferably, the thickness of the fibrous shell layer is 150-200 nm.

[0008] The present invention also provides a method for preparing the hydrophobic silica, comprising the following steps: uniformly dispersing porous silica in solution A, then adding an organic solvent and a silane coupling agent containing an epoxy group, mixing, reacting, and performing solid-liquid separation to obtain the hydrophobic silica.

[0009] The present invention uses porous silica as a core, selects a suitable solvent A and an organic solvent, causes a silane coupling agent containing an epoxy group to undergo hydrolysis and condensation, and uniformly generates fibrous silica on the surface of the porous silica to form a fibrous shell layer, and finally obtains sea urchin-like hydrophobic silica; this special structure enables the hydrophobic silica to have graded porosity, greatly increases its pore volume, and has a rough surface with a suitable particle size, so that the hydrophobic silica can be used as a matting agent in a variety of coatings, greatly improving the matting performance.

[0010] In addition, the present invention selects porous silica with a suitable particle size and forms nanoscale fibrous silica on its surface, so that the hydrophobic silica has a hierarchical micro-nano structure, which can improve its hydrophobic properties, and the epoxy groups contained on the surface of the fibrous silica can further improve its hydrophobic properties, so that it can be evenly dispersed in the coating, avoiding the problem of easy agglomeration of silica. In addition, the epoxy groups can also react with active groups (such as amino groups, hydroxyl groups, etc.) in the coating, thereby improving its stability in the coating, avoiding the occurrence of hard precipitation in the coating during storage, and increasing the mechanical properties of the coating film, such as scratch resistance.

[0011] Preferably, solution A is an aqueous solution of hexadecyltrimethylammonium bromide.

[0012] Preferably, the pH of solution A is 8.5-9.5. The pH of solution A is preferably adjusted with sodium hydroxide.

[0013] The invention selects a hexadecyltrimethylammonium bromide aqueous solution and an organic solvent to form a suitable oil-water system, and in an alkaline environment, a silane coupling agent containing an epoxy group undergoes hydrolysis and condensation to form fibrous silica, and the pH range is controlled to retain the epoxy groups on the surface of the fibrous silica.

[0014] Preferably, the concentration of cetyltrimethylammonium bromide is 0.04-0.05 g / ml.

[0015] Preferably, the weight ratio of hexadecyltrimethylammonium bromide to porous silica is 1:0.08-0.1.

[0016] Preferably, the organic solvent is a mixed solvent of n-hexane and isopropanol.

[0017] Preferably, the volume ratio of n-hexane to isopropanol is 25-30:1.

[0018] Preferably, the weight ratio of isopropyl alcohol to the silane coupling agent containing epoxy groups is 1:1.5-1.7.

[0019] Preferably, the weight ratio of the porous silica to the silane coupling agent containing an epoxy group is 1:15-20.

[0020] Preferably, the silane coupling agent containing an epoxy group is at least one of 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0021] The present invention selects a suitable type of silane coupling agent containing epoxy groups, dissolves it in an organic solvent, and selects n-hexane and isopropanol as organic solvents to form an oil-water mixed system with solution A, which can further promote the generation of fibrous silica by mutual cooperation. In addition, isopropanol can also appropriately expand the pores of porous silica, further increase the pore volume of hydrophobic silica, and improve the extinction performance.

[0022] Preferably, the reaction is kept at 55-65°C for 18-24 hours.

[0023] By selecting appropriate reaction conditions and suitable pH, the epoxy groups on the surface of fibrous silica can be retained, thereby improving the hydrophobicity and dispersibility.

[0024] The present invention also proposes the use of the hydrophobic silica in a matting agent.

[0025] Preferably, the invention is used in a matting agent for coatings.

[0026] The above-mentioned coating can be epoxy resin coating, polyurethane coating, polyacrylate coating, etc.

[0027] The present invention uses porous silica as a core, selects a suitable solvent A and an organic solvent, causes a silane coupling agent containing an epoxy group to undergo hydrolysis and condensation, and evenly generates fibrous silica on the surface of the porous silica to form a fibrous shell layer, and finally obtains sea urchin-like hydrophobic silica; this special structure enables the hydrophobic silica to have a good pore volume and particle size, and greatly improves its extinction performance; and the micro-nano structure cooperates with the epoxy group to greatly improve its hydrophobicity and dispersibility, and avoid the problem of easy agglomeration of silica. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described in detail below through specific embodiments.

[0029] Example 1

[0030] A hydrophobic silica comprises porous silica particles and fibrous silica, wherein the fibrous silica is uniformly loaded on the surface of the porous silica particles to form a fibrous shell layer, so that the hydrophobic silica is in the shape of a sea urchin, the surface of the fibrous silica contains epoxy groups, and the thickness of the fibrous shell layer is 180nm.

[0031] The preparation method of the hydrophobic silica comprises the following steps:

[0032] A 0.045 g / ml aqueous solution of hexadecyltrimethylammonium bromide was taken, and the pH was adjusted to 9.0 with a sodium hydroxide aqueous solution, which was recorded as solution A. Then, porous silica with a particle size of 5 μm was added and dispersed evenly by ultrasonication so that the weight ratio of hexadecyltrimethylammonium bromide to porous silica was 1:0.1, thereby obtaining a mixed solution 1.

[0033] n-hexane and isopropanol were mixed at a volume ratio of 28:1, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was added and mixed so that the weight ratio of isopropanol to 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was 1:1.6, to obtain a mixed solution 2;

[0034] Mixed solution 2 was added to mixed solution 1 so that the weight ratio of porous silica to 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was 1:17, and the mixture was stirred at a speed of 300 r / min for 30 min to mix well, and then the temperature was raised to 60° C. and kept for reaction for 20 h, filtered, washed, and dried at 50° C. to obtain hydrophobic silica.

[0035] Example 2

[0036] A hydrophobic silica comprises porous silica particles and fibrous silica, wherein the fibrous silica is uniformly loaded on the surface of the porous silica particles to form a fibrous shell layer, so that the hydrophobic silica is in the shape of a sea urchin, the surface of the fibrous silica contains epoxy groups, and the thickness of the fibrous shell layer is 150nm.

[0037] The preparation method of the hydrophobic silica comprises the following steps:

[0038] A 0.04 g / ml aqueous solution of hexadecyltrimethylammonium bromide was taken, and the pH was adjusted to 8.5 with a sodium hydroxide aqueous solution, which was recorded as solution A. Then, porous silica with a particle size of 6 μm was added, and ultrasonic dispersion was performed uniformly so that the weight ratio of hexadecyltrimethylammonium bromide to porous silica was 1:0.1, thereby obtaining a mixed solution 1.

[0039] n-hexane and isopropanol were mixed at a volume ratio of 25:1, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was added and mixed so that the weight ratio of isopropanol to 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was 1:1.7, to obtain a mixed solution 2;

[0040] Mixed solution 2 was added to mixed solution 1 so that the weight ratio of porous silica to 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was 1:15, and the mixture was stirred at a speed of 300 r / min for 30 min to mix well, and then the temperature was raised to 65° C. and kept for reaction for 18 h, filtered, washed, and dried at 50° C. to obtain hydrophobic silica.

[0041] Example 3

[0042] A hydrophobic silica comprises porous silica particles and fibrous silica, wherein the fibrous silica is uniformly loaded on the surface of the porous silica particles to form a fibrous shell layer, so that the hydrophobic silica is in the shape of a sea urchin, the surface of the fibrous silica contains epoxy groups, and the thickness of the fibrous shell layer is 200nm.

[0043] The preparation method of the hydrophobic silica comprises the following steps:

[0044] A 0.05 g / ml aqueous solution of hexadecyltrimethylammonium bromide was taken, and the pH was adjusted to 9.5 with a sodium hydroxide aqueous solution, which was recorded as solution A. Then, porous silica with a particle size of 4 μm was added and dispersed evenly by ultrasonication so that the weight ratio of hexadecyltrimethylammonium bromide to porous silica was 1:0.08, thereby obtaining a mixed solution 1.

[0045] n-hexane and isopropanol were mixed at a volume ratio of 30:1, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was added and mixed so that the weight ratio of isopropanol to 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was 1:1.5, to obtain a mixed solution 2;

[0046] Mixed solution 2 was added to mixed solution 1 so that the weight ratio of porous silica to 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane was 1:20, and the mixture was stirred at a speed of 300 r / min for 30 min to mix well, and then the temperature was raised to 55° C. and kept for reaction for 24 h, filtered, washed, and dried at 50° C. to obtain hydrophobic silica.

[0047] Comparative Example 1

[0048] A porous silica particle, which is the same as the porous silica in Example 1 and is from the same production batch.

[0049] Comparative Example 2

[0050] A hydrophobic silica, during the preparation process of which porous silica is not added, and the other steps are the same as the preparation method of Example 1.

[0051] Take the silica of Examples 1-3 and Comparative Examples 1-2, add them to polyacrylic acid resin coating (the formula of polyacrylic acid resin coating is: 78 parts of polyacrylate resin, 10 parts of diluent, 6 parts of film-forming aid, 0.5 parts of leveling agent, 0.5 parts of curing agent, 4 parts of wax emulsion, 1 part of other additives) according to the same weight ratio and mix them evenly. According to GB / T 9754-2007, the 60° surface glossiness of the paint film is tested; and the paint is stored at 50°C for 7 days, and the upper layer of paint liquid is taken, and the 60° surface glossiness of the paint film is measured by the same method; in addition, the water contact angle of the paint film is tested. The pore volume of the silica of Examples 1-3 and Comparative Examples 1-2 is tested respectively. The test results are shown in Table 1.

[0052] Table 1 Test results

[0053]

[0054] It can be seen from Table 1 that the hydrophobic silica of the present invention has good matting performance and hydrophobic performance, and has good dispersion stability in the coating, and can avoid the problem of hard precipitation.

[0055] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A hydrophobic silica, characterized in that The invention comprises porous silica particles and fibrous silica. The fibrous silica is uniformly loaded on the surface of the porous silica particles to form a fibrous shell layer, so that the hydrophobic silica is in the shape of a sea urchin. The surface of the fibrous silica contains epoxy groups.

2. The hydrophobic silica according to claim 1, characterized in that The particle size of porous silica is 4-6 μm.

3. The hydrophobic silica according to claim 1 or 2, characterized in that The thickness of the fibrous shell is 150-200 nm.

4. A method for preparing the hydrophobic silica according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: uniformly dispersing porous silica in solution A, then adding an organic solvent and a silane coupling agent containing an epoxy group, mixing, reacting, and performing solid-liquid separation to obtain hydrophobic silica.

5. The method for preparing hydrophobic silica according to claim 4, characterized in that: Solution A is an aqueous solution of hexadecyltrimethylammonium bromide; preferably, the pH of solution A is 8.5-9.5; preferably, the concentration of hexadecyltrimethylammonium bromide is 0.04-0.05 g / ml; preferably, the weight ratio of hexadecyltrimethylammonium bromide to porous silica is 1:0.08-0.

1.

6. The method for preparing hydrophobic silica according to claim 4 or 5, characterized in that: The organic solvent is a mixed solvent of n-hexane and isopropanol; preferably, the volume ratio of n-hexane to isopropanol is 25-30:1; preferably, the weight ratio of isopropanol to the silane coupling agent containing epoxy groups is 1:1.5-1.

7.

7. The method for preparing hydrophobic silica according to any one of claims 4 to 6, characterized in that: The weight ratio of the porous silica to the silane coupling agent containing an epoxy group is 1:15-20.

8. The method for preparing hydrophobic silica according to any one of claims 4 to 7, characterized in that: The silane coupling agent containing an epoxy group is at least one of 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

9. The method for preparing hydrophobic silica according to any one of claims 4 to 8, characterized in that: Keep the reaction at 55-65°C for 18-24h.

10. Use of the hydrophobic silica according to any one of claims 1 to 3 in a matting agent; preferably, use in a matting agent for coatings.

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