Styrene-butadiene emulsion internal support type silicon dioxide hydrogel and preparation method of coating film of styrene-butadiene emulsion internal support type silicon dioxide hydrogel

Abstract

The invention relates to the technical field of gel, and particularly discloses styrene-butadiene emulsion internal support type silicon dioxide hydrogel and a preparation method of a coating film of the styrene-butadiene emulsion internal support type silicon dioxide hydrogel. The preparation method of the styrene-butadiene emulsion internal support type silicon dioxide hydrogel comprises the following steps: uniformly mixing and grinding iron ore tailings and sodium hydroxide, calcining at 500-700 DEG C for 1-5 hours, cooling and grinding to obtain an alkali-fired material; adding water into the alkali burning material, stirring, and separating to obtain supernate; adjusting the pH value of the supernate to 8-11, and standing and aging for 1-3 days to obtain hydrogel; and adding a styrene-butadiene emulsion into the hydrogel for permeation replacement, and taking out the hydrogel. The characteristics of polymer emulsion fluid are utilized, the size of polymer particles is smaller than the size of pore channels in the hydrogel, and the particles of the polymer emulsion are permeated into the pore channels of the hydrogel according to the fluid diffusion and permeation principle, so that the purpose of enhancing the gel strength is achieved. The styrene-butadiene emulsion internal support type silicon dioxide hydrogel coating film is obtained by coating the hydrogel and then drying.

Description

Technical Field

[0001] The invention relates to the technical field of gel, and in particular to a preparation method of a styrene-butadiene emulsion-supported silica hydrogel and a coating thereof. Background Art

[0002] Silica aerogel is a spatial network structure composed of nanoparticles, which has the characteristics of low density, large specific surface area, ultra-low thermal conductivity, low refractive index and low sound propagation speed. Therefore, it has broad application prospects in many fields such as thermal insulation, sound insulation, catalyst carriers, adsorbents, drug delivery and optical devices. It is precisely because of these excellent properties of silica aerogel that it attracts great attention from scientific researchers to its preparation technology and performance.

[0003] The silica aerogel skeleton has a three-dimensional network structure shaped like a pearl necklace. The secondary particles are connected by point contact, with a small contact area and weak bonds between the particles. As a result, when subjected to external forces, the neck area between the secondary particles is easily broken, causing the connection between the particles to be disconnected, the gel skeleton to collapse, and the aerogel to lose its excellent performance.

[0004] At present, the main methods to avoid structural collapse during the preparation process of wet gel to aerogel include sol-gel aging enhancement, new drying technology and load enhancement.

[0005] However, the aging enhancement process takes a long time and will cause problems such as reduced specific surface area, increased pore size, increased density, and reduced light transmittance.

[0006] The use of novel drying techniques (such as supercritical carbon dioxide drying) can replace the solvent in the wet gel with supercritical carbon dioxide, thereby significantly reducing the changes in the solvent surface tension during the drying process that lead to the shrinkage and collapse of the aerogel skeleton. However, this method is expensive and has high cost.

[0007] Load enhancement requires the introduction of reinforcing phases, such as fibers, whiskers, particles, etc., and the use of composite process technology to prepare composite materials. As a mechanical support, the reinforcing phase disperses the external energy on the silica aerogel matrix skeleton, and at the same time has the function of conducting and consuming energy for external stress, thereby blocking the expansion of cracks, which can significantly improve the mechanical properties of silica aerogel composite materials and significantly improve the strength of silica aerogel. However, the load is often solid phases such as fibers and whiskers, and there are obvious differences in the properties of the interface between the two phases, which makes it difficult to evenly disperse the reinforcing phase in the composite material, affecting the comprehensive performance of the composite material. Summary of the invention

[0008] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method for preparing a styrene-butadiene emulsion-supported silica hydrogel and a coating thereof.

[0009] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0010] S1. Mix the iron ore tailings and sodium hydroxide and grind them evenly, calcine at 500-700℃ for 1-5h, and grind them after cooling to obtain alkali-burned material (whose main component is Na m SiO n and a small amount of impurities in the solid powder);

[0011] S2, adding water to the alkali-burned material and stirring, separating and obtaining a supernatant; adjusting the pH value of the supernatant to 8-11, standing and aging for 1-3 days to obtain a hydrogel;

[0012] S3, adding styrene butadiene emulsion to the hydrogel for osmotic displacement, and removing excess styrene butadiene emulsion.

[0013] Preferably, in S1, the mass ratio of iron ore tailings to sodium hydroxide is 1:1-3.

[0014] Preferably, in S2, the mass ratio of the alkali-burned material to water is 1:1-5.

[0015] Preferably, in S2, separation is performed by centrifugation at a speed of 3000-10000 rpm.

[0016] Preferably, in S2, the pH value of the supernatant is adjusted to 8-11 using hydrochloric acid with a mass fraction of 1-5%.

[0017] Preferably, in S3, the particle size of the styrene-butadiene emulsion is ≤20 nm.

[0018] Preferably, in S3, the specific operation of the osmotic replacement is as follows: add styrene butadiene emulsion to the hydrogel and let it stand for 1-3 days, with the volume ratio of hydrogel to styrene butadiene emulsion being 1:1-3; then replace the styrene butadiene emulsion and let it stand again for 1-3 days, and repeat the replacement of the styrene butadiene emulsion 3-5 times.

[0019] A styrene-butadiene emulsion-supported silica hydrogel is prepared by adopting the preparation method of the styrene-butadiene emulsion-supported silica hydrogel.

[0020] A styrene-butadiene emulsion internally supported silica hydrogel coating film is obtained by coating the styrene-butadiene emulsion internally supported silica hydrogel and then drying it.

[0021] Specifically, the above-mentioned styrene-butadiene emulsion-supported silica hydrogel is coated on the surface of a clean glass slide and dried at room temperature to obtain a coating film in which the gel is evenly distributed at the molecular level.

[0022] The present invention utilizes the characteristics of polymer emulsion fluid, and the size of polymer particles is smaller than the size of the pores in the hydrogel. Through the principle of fluid diffusion and penetration, the particles of polymer emulsion penetrate into the pores of the hydrogel, thereby achieving the purpose of enhancing the strength of the gel; and a novel polymer internally modified hydrogel is prepared. The hydrogel is evenly coated on a glass slide and dried at room temperature to obtain a coating film with uniform gel distribution, which provides a new idea for the development and application of hydrogels and the preparation of aerogels. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 7001 is the XRD spectrum of the alkali-calcined material obtained in Example 2, Example 5 and Example 8; wherein, 7002 is the XRD spectrum of the alkali-calcined material obtained in Example 5, 7003 is the XRD spectrum of the alkali-calcined material obtained in Example 8, and 16-0818 and 36-0112 are standard cards of Na2SiO3 and Na4SiO4, respectively.

[0024] Figure 2 6001 is the XRD spectrum of the alkali-calcined material obtained in Example 6, 6002 is the XRD spectrum of the alkali-calcined material obtained in Example 7, 6003 is the XRD spectrum of the alkali-calcined material obtained in Example 1, and 16-0818 and 36-0112 are standard cards of Na2SiO3 and Na4SiO4, respectively.

[0025] Figure 3 These are photos of the hydrogel, styrene-butadiene emulsion-supported silica hydrogel and coating obtained in Example 8; wherein a is a photo of the hydrogel, b is a photo of the styrene-butadiene emulsion-supported silica hydrogel, and c is a photo of the styrene-butadiene emulsion-supported silica hydrogel coating. DETAILED DESCRIPTION

[0026] The present invention will be further explained below in conjunction with specific embodiments.

[0027] The components of the iron ore tailings used are shown in Table 1:

[0028] Table 1

[0029]

[0030]

[0031] Example 1

[0032] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0033] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:3, place in a muffle furnace and calcine at 600°C for 3h, and grind into powder after natural cooling to obtain alkali-burned material;

[0034] S2, add 1 times (volume) of water to the alkali-burned material, stir and wash for 3 minutes, then centrifuge at 3000 rpm, stir and wash the precipitate obtained by centrifugation twice again, and combine the supernatant;

[0035] The obtained supernatant was continuously stirred, and during the stirring process, 1% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 1 day, and then washed 3 times with 1-fold (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0036] S3. Add 1 volume of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel and let it stand for 1 day. Then replace the styrene butadiene emulsion and let it stand for another day. Repeat the replacement of the styrene butadiene emulsion 3 times and then pour off the excess styrene butadiene emulsion on the top.

[0037] Example 2

[0038] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0039] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:1, place in a muffle furnace and calcine at 700°C for 3h, and grind into powder after natural cooling to obtain alkali-burned material;

[0040] S2, add 5 times (volume) of water to the alkali-burned material, stir and wash for 5 minutes, then centrifuge at 10000 rpm, stir and wash the precipitate obtained by centrifugation 4 times again, and combine the supernatant;

[0041] The obtained supernatant was continuously stirred, and during the stirring process, 5% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 3 days, and then washed 5 times with 3 times (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0042] S3. Add 3 times (volume) of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel and let it stand for 3 days. Then replace the styrene butadiene emulsion and let it stand for another 3 days. Repeat the replacement of the styrene butadiene emulsion 5 times and then pour off the excess styrene butadiene emulsion on the top.

[0043] Example 3

[0044] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0045] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:1.5, place in a muffle furnace and calcine at 650°C for 2h, and grind into powder after natural cooling to obtain alkali-burned material;

[0046] S2, add 4 times (volume) of water to the alkali-burned material, stir and wash for 3.5 minutes, then centrifuge at 8000 rpm, stir and wash the precipitate obtained by centrifugation 3 times again, and combine the supernatant;

[0047] The obtained supernatant was continuously stirred, and during the stirring process, 2% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 2.5 days, and then washed 4 times with 1.5 times (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0048] S3. Add 2.5 times (volume) of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel, let it stand for 1.5 days, then replace the styrene butadiene emulsion and let it stand for another 2.5 days. Repeat the replacement of the styrene butadiene emulsion 4 times, and then pour off the excess styrene butadiene emulsion on the top.

[0049] Example 4

[0050] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0051] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:2.5, place in a muffle furnace and calcine at 550° C. for 4 hours, and grind into powder after natural cooling to obtain alkali-burned material;

[0052] S2, add 2 times (volume) of water to the alkali-burned material, stir and wash for 4.5 minutes, then centrifuge at 6000 rpm, stir and wash the precipitate obtained by centrifugation again for 3 times, and combine the supernatant;

[0053] The obtained supernatant was continuously stirred, and during the stirring process, 4% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 1.5 days, and then washed 4 times with 2.5 times (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0054] S3. Add 1.5 times (volume) of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel and let it stand for 2.5 days, then replace the styrene butadiene emulsion and let it stand for another 1.5 days. Repeat the replacement of the styrene butadiene emulsion 4 times, and then pour off the excess styrene butadiene emulsion on the top.

[0055] Example 5

[0056] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0057] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:2, place in a muffle furnace and calcine at 700°C for 3h, and grind into powder after natural cooling to obtain alkali-burned material;

[0058] S2, add 3 times (volume) of water to the alkali-burned material, stir and wash for 4 minutes, then centrifuge at 7000 rpm, stir and wash the precipitate obtained by centrifugation 3 times again, and combine the supernatant;

[0059] The obtained supernatant was continuously stirred, and during the stirring process, 3% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 2 days, and then washed 4 times with 2 times (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0060] S3. Add 2 times (volume) of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel and let it stand for 2 days. Then replace the styrene butadiene emulsion and let it stand for another 2 days. Repeat the replacement of the styrene butadiene emulsion 4 times and then pour off the excess styrene butadiene emulsion on the top.

[0061] Example 6

[0062] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0063] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:1, place in a muffle furnace and calcine at 600°C for 3h, and grind into powder after natural cooling to obtain alkali-burned material;

[0064] S2, add 3 times (volume) of water to the alkali-burned material, stir and wash for 4 minutes, then centrifuge at 7000 rpm, stir and wash the precipitate obtained by centrifugation 3 times again, and combine the supernatant;

[0065] The obtained supernatant was continuously stirred, and during the stirring process, 3% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 2 days, and then washed 4 times with 2 times (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0066] S3. Add 2 times (volume) of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel and let it stand for 2 days. Then replace the styrene butadiene emulsion and let it stand for another 2 days. Repeat the replacement of the styrene butadiene emulsion 4 times and then pour off the excess styrene butadiene emulsion on the top.

[0067] Example 7

[0068] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0069] S1. Mix and grind the iron ore tailings and sodium hydroxide evenly, the mass ratio of the iron ore tailings to sodium hydroxide is 1:2, place in a muffle furnace and calcine at 600°C for 3h, and grind into powder after natural cooling to obtain alkali-burned material;

[0070] S2, add 3 times (volume) of water to the alkali-burned material, stir and wash for 4 minutes, then centrifuge at 7000 rpm, stir and wash the precipitate obtained by centrifugation 3 times again, and combine the supernatant;

[0071] The obtained supernatant was continuously stirred, and during the stirring process, 3% hydrochloric acid was added dropwise to adjust the pH value of the system to 8-11, and the mixture was allowed to stand for 2 days, and then washed 4 times with 2 times (volume) deionized water to remove impurities such as sodium chloride, thereby obtaining a hydrogel;

[0072] S3. Add 2 times (volume) of styrene butadiene emulsion with a particle size of ≤20 nm to the hydrogel and let it stand for 2 days. Then replace the styrene butadiene emulsion and let it stand for another 2 days. Repeat the replacement of the styrene butadiene emulsion 4 times and then pour off the excess styrene butadiene emulsion on the top.

[0073] Example 8

[0074] A method for preparing a styrene-butadiene emulsion-supported silica hydrogel comprises the following steps:

[0075] 10 g of iron ore tailings and 30 g of sodium hydroxide were ground and mixed evenly, put into a muffle furnace, calcined at 700° C. for 3 hours, cooled naturally to room temperature, and ground into powder (i.e., alkali-calcined material).

[0076] Take 0.4g of the calcined powder, add 10mL of deionized water, stir and wash thoroughly, transfer to a 10mL centrifuge tube, centrifuge at 10000r / min for 3 minutes to obtain a primary supernatant, which is colorless or light yellow. The separated solid residue is fully washed with 5mL of deionized water and centrifuged under the same conditions to obtain a secondary supernatant. Slowly add the secondary supernatant to the primary supernatant under stirring, and then slowly add 5% by mass hydrochloric acid to adjust the pH value of the supernatant to 10. Stop stirring, let it stand for 3 days to form a hydrogel. Add 3 times the volume of deionized water to the hydrogel and wash it thoroughly. Change the water every 5 hours and wash it again. Repeat 5 times to completely wash away the sodium chloride in the gel.

[0077] After washing with water, add 3 times the volume of styrene butadiene emulsion for osmotic diffusion, replace the styrene butadiene emulsion every 2 days, repeat 5 times, pour off the excess styrene butadiene emulsion on the top, and obtain the styrene butadiene emulsion-supported silica hydrogel.

[0078] The styrene-butadiene emulsion-supported silica hydrogel was coated on a clean glass slide and dried at room temperature for 24 hours to form a transparent coating film with uniform distribution of the gel.

[0079] X-ray diffraction was performed on the alkali-calcined materials obtained in Example 2, Example 5 and Example 8. Figure 1 As shown, 7001 is the XRD spectrum of the alkali-calcined material obtained in Example 2, 7002 is the XRD spectrum of the alkali-calcined material obtained in Example 5, 7003 is the XRD spectrum of the alkali-calcined material obtained in Example 8, and 16-0818 and 36-0112 are standard cards of Na2SiO3 and Na4SiO4, respectively.

[0080] like Figure 1 As shown in the figure, after the mass ratio of iron ore tailings and sodium hydroxide changes from 1:1 to 1:3, the product gradually changes from Na2SiO3 to Na4SiO4. When the alkali content is low, the SiO2 that has not yet reacted in the iron ore tailings shows an obvious diffraction peak, as shown by the ◆ on 7001 in the figure. Therefore, when treating iron ore tailings, it is preferred to calcine them with a mass ratio of 1:3.

[0081] X-ray diffraction was performed on the alkali-calcined materials obtained in Example 1, Example 6 and Example 7. Figure 2 As shown, 6001 is the XRD spectrum of the alkali-calcined material obtained in Example 6, 6002 is the XRD spectrum of the alkali-calcined material obtained in Example 7, and 6003 is the XRD spectrum of the alkali-calcined material obtained in Example 1.

[0082] like Figure 2 As shown, its changing pattern is Figure 1 Similarly, at 600℃, when the alkali-to-material ratio is 1:1, an obvious SiO2 diffraction peak that has not yet reacted appears, which comes from the tailings, represented by ◆ in the figure. Therefore, when treating iron ore tailings, it is also preferred to calcine them at a mass ratio of 1:3.

[0083] The photos of the hydrogel, styrene-butadiene emulsion-supported silica hydrogel and coating obtained in Example 8 are as follows Figure 3 As shown, it changes from an almost transparent colloid to a milky white colloid, and finally forms a colorless and transparent coating film.

[0084] 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 method for preparing a butadiene-styrene emulsion-supported silica hydrogel, characterized in that: The steps include: S1. Mix the iron ore tailings and sodium hydroxide and grind them evenly, calcine them at 500-700°C for 1-5h, and grind them after cooling to obtain alkali-burned materials; S2, adding water to the alkali-burned material and stirring, separating and obtaining a supernatant; adjusting the pH value of the supernatant to 8-11, standing and aging for 1-3 days to obtain a hydrogel; S3, adding styrene butadiene emulsion to the hydrogel for osmotic displacement, and removing excess styrene butadiene emulsion.

2. The method for preparing the styrene-butadiene emulsion-supported silica hydrogel according to claim 1, characterized in that: In S1, the mass ratio of iron ore tailings to sodium hydroxide is 1:1-3.

3. The method for preparing the butadiene-styrene emulsion-supported silica hydrogel according to claim 1, characterized in that: In S2, the mass ratio of alkali-burned material to water is 1:1-5.

4. The method for preparing the styrene-butadiene emulsion-supported silica hydrogel according to claim 1, characterized in that: In S2, separation is performed by centrifugation, and the centrifugal speed is 3000-10000 rpm.

5. The method for preparing the styrene-butadiene emulsion-supported silica hydrogel according to claim 1, characterized in that: In S2, the pH value of the supernatant is adjusted to 8-11 using hydrochloric acid with a mass fraction of 1-5%.

6. The method for preparing the styrene-butadiene emulsion-supported silica hydrogel according to claim 1, characterized in that: In S3, the particle size of the styrene-butadiene emulsion is ≤20nm.

7. The method for preparing the styrene-butadiene emulsion-supported silica hydrogel according to claim 1, characterized in that: In S3, the specific operation of the osmotic replacement is as follows: add styrene butadiene emulsion to the hydrogel and let it stand for 1-3 days, with the volume ratio of hydrogel to styrene butadiene emulsion being 1:1-3; then replace the styrene butadiene emulsion and let it stand again for 1-3 days, and repeat the replacement of the styrene butadiene emulsion 3-5 times.

8. A butadiene-styrene emulsion-supported silica hydrogel, characterized in that: The silica hydrogel is prepared by the method for preparing the styrene-butadiene emulsion-supported silica hydrogel according to any one of claims 1 to 7.

9. A styrene-butadiene emulsion-supported silica hydrogel coating film, characterized in that: The method is obtained by coating the styrene-butadiene emulsion-supported silica hydrogel as described in claim 8 and then drying it.

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