Modified silica powder, preparation method thereof and application of modified silica powder in functional filler

Abstract

The invention relates to the technical field of silica powder, and discloses modified silica powder, a preparation method thereof and application of the modified silica powder in functional filler. N-Boc-serinol, hexamethylene diisocyanate, N-dodecyl succinic anhydride and the like are used as reactants to prepare the modified silica powder with polyurethane as a main chain and polyurethane as a main chain; the side chain of the comb-type polyurethane dispersing agent contains carboxyl and a dodecyl long chain. The comb-shaped alkyl long chain of the dispersing agent can form steric hindrance, and meanwhile, mutual repulsive force is formed among the silicon micro-powder to overcome the agglomeration phenomenon caused by mutual attraction, so that the silicon micro-powder has smaller particle size. The modified silica powder has good dispersibility in organic solvents such as water, dichloromethane, N, N-dimethylformamide and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of silica powder, and specifically to a modified silica powder, a preparation method thereof, and an application thereof in functional fillers. Background Art

[0002] The main component of silica powder is silicon dioxide. It has small particle size, large specific surface area, high mechanical strength, and the raw materials are cheap and easy to obtain. The preparation method is simple. It is widely used in polymer materials such as coatings, adhesives, plastics, and rubbers, and can improve the mechanical strength, hardness, heat resistance and other properties of the materials. However, there are electrostatic and other interactions between silica powder particles, and its dispersibility in media such as water and organic solvents is poor, and it is easy to agglomerate, which hinders the practical application of silica powder.

[0003] Dispersants can improve the dispersibility of materials such as inorganic fillers and nanoparticles and inhibit their agglomeration. There are mainly organic small molecule dispersants, comb-shaped polymer dispersants, star-shaped polymer dispersants, etc. The literature "Synthesis and Properties of Polyurethane Hyperdispersants for Silica Aqueous Dispersions" reported that polyurethane hyperdispersants with alkoxysilane anchoring groups and polyethylene glycol solvation segments were used to modify silica, and a stable aqueous dispersion of silica matting powder with small particle size and no agglomeration could be obtained. However, the silica in this literature did not show good dispersibility in organic solvents such as N,N-dimethylformamide. Summary of the Invention

[0004] (1) Technical problem to be solved: The present invention solves the problem of poor dispersibility of silica powder in solvents such as water, dichloromethane, and N,N-dimethylformamide.

[0005] (2) Technical solution: A preparation method of a modified silica powder:

[0006] (1) Add N-Boc-serinol and hexamethylene diisocyanate to dichloromethane, introduce nitrogen, stir and reflux at 40-45 °C for 3-4 h, cool to room temperature, add trifluoroacetic acid, stir at 20-30 °C for 4-6 h, concentrate under reduced pressure, wash with 5% sodium carbonate solution and acetone, and dry to obtain a polyurethane dispersant precursor. The reaction formula is:

[0007]

[0008] (2) Add the polyurethane dispersant precursor to N,N-dimethylformamide, stir and then add N-dodecyl succinic anhydride, stir at 15-30 °C for 12-18 h, concentrate under reduced pressure, wash with acetone, and dry to obtain a comb-shaped polyurethane dispersant. The reaction mechanism is:

[0009]

[0010] (3), Add silica fume into water, disperse it by ultrasonic, then add comb-shaped polyurethane dispersant and sodium hydroxide for surface modification, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain modified silica fume.

[0011] Preferably, in (1), the molar ratio of N-Boc-serinol, hexamethylene diisocyanate, and trifluoroacetic acid is (1 - 1.1):1:(3 - 4).

[0012] Preferably, in (2), the mass ratio of polyurethane dispersant precursor to N-dodecyl succinic anhydride is 100:(15 - 40).

[0013] Preferably, in (3), add sodium hydroxide to adjust the pH of the solution to 7 - 8.

[0014] Preferably, in (3), the mass ratio of silica fume to comb-shaped polyurethane dispersant is 100:(3 - 20).

[0015] Preferably, in (3), add sodium hydroxide to adjust the pH of the solution to 7 - 8.

[0016] Preferably, in (3), the surface modification is carried out at 70 - 90 °C for 2 - 3 h.

[0017] Preferably, the modified silica fume is applied to functional fillers.

[0018] (III) Technical effects: In the present invention, N-Boc-serinol, hexamethylene diisocyanate, N-dodecyl succinic anhydride, etc. are used as reactants to prepare a comb-shaped polyurethane dispersant with a polyurethane main chain and carboxyl and dodecyl long chains on the side chains.

[0019] In the comb-shaped polyurethane dispersant of the present invention, at high temperature, the carboxyl groups on the side chains interact with the hydroxyl groups on the surface of silica fume, realizing the surface modification of silica fume. Its comb-shaped alkyl long chains can form a steric hindrance effect, and at the same time, make the silica fume particles have a repulsive force with each other, overcoming the phenomenon of aggregation due to mutual attraction, so that the silica fume has a smaller particle size.

[0020] The comb-shaped polyurethane dispersant of the present invention contains hydrophilic carboxyl groups and amide bonds, making the modified silica fume have good affinity for water and showing good dispersibility in water. And the alkyl long chains contained as solvation chains have a strong solvation effect, making the modified silica fume also have good dispersibility in organic solvents such as dichloromethane and N,N-dimethylformamide.

[0021] The modified silica fume of the present invention can be used as a functional filler and reinforcing agent, and has broad application prospects in high molecular materials such as waterborne coatings, solvent-based coatings, plastics, and rubbers. Detailed implementation methods

[0022] 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 the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Silica powder, Lister Electronic Materials Co., Ltd.

[0024] The CAS number of N-Boc-serinol is 125414-41-7. The CAS number of hexamethylene diisocyanate is 822-06-0. The CAS number of N-dodecyl succinic anhydride is 2561-85-5.

[0025] Example 1:

[0026] (1) Add 20 mmol of N-Boc-serinol and 20 mmol of hexamethylene diisocyanate to 15 mL of dichloromethane, introduce nitrogen, stir and reflux at 45 °C for 3 h, cool to room temperature, add 70 mmol of trifluoroacetic acid, stir at 25 °C for 6 h, concentrate under reduced pressure, wash with 5% sodium carbonate solution and acetone, and dry to obtain a polyurethane dispersant precursor.

[0027] (2) Add 1 g of the polyurethane dispersant precursor to 10 mL of N,N-dimethylformamide, stir and then add 0.15 g of N-dodecyl succinic anhydride, stir at 15 °C for 18 h, concentrate under reduced pressure, wash with acetone, and dry to obtain a comb-shaped polyurethane dispersant.

[0028] (3) Add 5 g of silica powder to 80 mL of water, ultrasonically disperse, then add 0.15 g of the comb-shaped polyurethane dispersant, add sodium hydroxide to adjust the pH of the solution to 8, stir at 80 °C for surface modification for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain modified silica powder.

[0029] Comparative Example 1:

[0030] (1) Add 5 g of silica powder to 80 mL of water, ultrasonically disperse, then add 0.15 g of the polyurethane dispersant precursor (prepared in the same way as in Example 1), add sodium hydroxide to adjust the pH of the solution to 8, stir at 80 °C for surface modification for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain modified silica powder.

[0031] Comparative Example 2:

[0032] (1) Add 1 g of polyurethane dispersant precursor (prepared in the same way as in Example 1) to 10 mL of N,N-dimethylformamide. After stirring, add 0.15 g of succinic anhydride, stir and react at 15 °C for 18 h, concentrate under reduced pressure, wash with acetone, and dry to obtain the polyurethane dispersant.

[0033] (2) Add 5 g of silica powder to 80 mL of water, disperse ultrasonically, then add 0.15 g of comb-shaped polyurethane dispersant, add sodium hydroxide to adjust the pH of the solution to 8, stir and perform surface modification at 80 °C for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain the modified silica powder.

[0034] Comparative Example 3:

[0035] (1) Add 5 g of silica powder to 80 mL of water, disperse ultrasonically, then add 0.15 g of stearic acid, add sodium hydroxide to adjust the pH of the solution to 8, stir and perform surface modification at 80 °C for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain the modified silica powder.

[0036] Example 2:

[0037] (1) Add 22 mmol of N-Boc-serinol and 20 mmol of hexamethylene diisocyanate to 20 mL of dichloromethane, introduce nitrogen, stir and reflux under condensation at 40 °C for 4 h, cool to room temperature, add 80 mmol of trifluoroacetic acid, stir and react at 20 °C for 6 h, concentrate under reduced pressure, wash with 5% sodium carbonate solution and acetone, and dry to obtain the polyurethane dispersant precursor.

[0038] (2) Add 1 g of polyurethane dispersant precursor to 15 mL of N,N-dimethylformamide. After stirring, add 0.28 g of N-dodecyl succinic anhydride, stir and react at 20 °C for 18 h, concentrate under reduced pressure, wash with acetone, and dry to obtain the comb-shaped polyurethane dispersant.

[0039] (3) Add 5 g of silica powder to 80 mL of water, disperse ultrasonically, then add 0.15 g of comb-shaped polyurethane dispersant, add sodium hydroxide to adjust the pH of the solution to 8, stir and perform surface modification at 90 °C for 2 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain the modified silica powder.

[0040] Example 3:

[0041] (1), Add 20 mmol of N-Boc-serinol and 20 mmol of hexamethylene diisocyanate to 15 mL of dichloromethane, introduce nitrogen gas, stir and reflux at 40 °C for 4 h, cool to room temperature, add 60 mmol of trifluoroacetic acid, stir and react at 30 °C for 4 h, concentrate under reduced pressure, wash with 5% sodium carbonate solution and acetone, and dry to obtain the polyurethane dispersant precursor.

[0042] (2), Add 1 g of the polyurethane dispersant precursor to 15 mL of N,N-dimethylformamide, stir and then add 0.4 g of N-dodecyl succinic anhydride, stir and react at 30 °C for 12 h, concentrate under reduced pressure, wash with acetone, and dry to obtain the comb-shaped polyurethane dispersant.

[0043] (3), Add 5 g of silica powder to 80 mL of water, disperse ultrasonically, then add 0.15 g of the comb-shaped polyurethane dispersant, add sodium hydroxide to adjust the pH of the solution to 7, stir at 70 °C for surface modification for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain the modified silica powder.

[0044] Example 4:

[0045] (1), Add 5 g of silica powder to 100 mL of water, disperse ultrasonically, then add 0.6 g of the comb-shaped polyurethane dispersant (prepared in the same way as in Example 2), add sodium hydroxide to adjust the pH of the solution to 8, stir at 90 °C for surface modification for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain the modified silica powder.

[0046] Example 5:

[0047] (1), Add 5 g of silica powder to 110 mL of water, disperse ultrasonically, then add 1 g of the comb-shaped polyurethane dispersant (prepared in the same way as in Example 2), add sodium hydroxide to adjust the pH of the solution to 8, stir at 90 °C for surface modification for 3 h, filter, wash successively with water, N,N-dimethylformamide, and ethanol, and dry to obtain the modified silica powder.

[0048] Add 0.1 g of the modified silica powder to 30 mL of distilled water, stir for 30 min, measure the particle size of the silica powder by a full-automatic particle size analyzer, and the scattering light angle is 90° during the measurement. Each group of samples is measured 5 times and the average value is taken. The test results are shown in Table 1.

[0049] Table 1 Particle size test of silica powder

[0050]

[0051]

[0052] Add 0.1 g of modified silica powder to 30 mL of solvent, stir for 30 min, then transfer it to a graduated cylinder, let it stand for 24 h, and measure the sedimentation volume of the suspension in the lower layer. The larger the sedimentation volume, the better the dispersibility. The test results are shown in Table 2.

[0053] Table 2 Test of Sedimentation Volume of Suspension

[0054]

[0055] After testing, the average particle size of the modified silica powder in Examples 1-5 is only 332.9 - 872.5 nm, and the sedimentation volume of the suspension in solvents such as distilled water, dichloromethane, and N,N-dimethylformamide is high, and the dispersibility is better.

[0056] Compared with Example 1, in Comparative Example 1, a polyurethane dispersant precursor is used as the dispersant, and in Comparative Example 2, succinic anhydride is used to replace N-dodecyl succinic anhydride to prepare a polyurethane dispersant. The modification effects of both on silica powder are poor, and the silica powder is prone to agglomeration, resulting in a large particle size, and the sedimentation volume of the suspension in solvents such as distilled water, dichloromethane, and N,N-dimethylformamide is low, and the dispersibility is poor.

[0057] In Comparative Example 3, the surface of silica powder is modified with conventional stearic acid. The particle size of the silica powder is large, the sedimentation volume of the suspension in solvents such as distilled water, dichloromethane, and N,N-dimethylformamide is low, and the dispersibility is low and the dispersibility is not good.

Claims

1. A preparation method of modified silica powder, characterized in that, The preparation method comprises the following steps: (1) Add N-Boc-serinol and hexamethylene diisocyanate to dichloromethane, introduce nitrogen, carry out a first reaction, cool to room temperature, add trifluoroacetic acid, carry out a second reaction, concentrate under reduced pressure, wash, and dry to obtain a polyurethane dispersant precursor; (2) Add the polyurethane dispersant precursor to N,N-dimethylformamide, stir and then add N-dodecyl succinic anhydride, carry out a reaction, concentrate under reduced pressure, wash, and dry to obtain a comb-shaped polyurethane dispersant; (3) Add silica powder to water, disperse ultrasonically, then add the comb-shaped polyurethane dispersant and sodium hydroxide, carry out surface modification, filter, wash, and dry to obtain modified silica powder.

2. The modified silica powder according to claim 1, wherein In the step (1), the first reaction is carried out under reflux condensation at 40-45 °C for 3-4 h; the second reaction is carried out at 20-30 °C for 4-6 h.

3. The modified silica powder according to claim 1, wherein, In the step (1), the molar ratio of N-Boc-serinol, hexamethylene diisocyanate, and trifluoroacetic acid is (1-1.1):1:(3-4).

4. The modified silica powder according to claim 1, characterized in that, In the step (2), the mass ratio of the polyurethane dispersant precursor to N-dodecyl succinic anhydride is 100:(15-40).

5. The modified silica powder according to claim 1, wherein In the step (2), the reaction is carried out at 15-30 °C for 12-18 h.

6. The modified silica powder according to claim 1, wherein, In the step (3), the mass ratio of the silica powder to the comb-shaped polyurethane dispersant is 100:(3-20).

7. The modified silica powder according to claim 1, wherein In the step (3), sodium hydroxide is added to adjust the pH of the solution to 7-8.

8. The modified silica powder according to claim 1, wherein In the step (3), the surface modification is carried out at 70-90 °C for 2-3 h.

9. Modified silica powder obtained by the preparation method according to any one of claims 1-8.

10. Application of the modified silica powder according to claim 9 in functional fillers.

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