Calcium ion enhanced, heat-insulating and hydrophobic integrated phenolic silica aerogel material and preparation method thereof

Abstract

The preparation method comprises the following steps: taking phenol, aldehyde and phenolic resin as raw materials, taking deionized water as a solvent, taking a surfactant and an alkaline agent as catalysis, adopting sectional gelling, and then introducing methylsilane and sodium silicate, so as to prepare the calcium ion enhanced heat-insulation hydrophobic phenolic silica aerogel material. And replacing with a calcium ion solution to prepare the calcium ion reinforced phenolic silicon oxide aerogel. Calcium ions can enhance the mechanical property of the material through the action of divalent positive ions between phenolic resin and silicate ester, and the compressive strength and structural stability of the material are improved, so that the overall mechanical property of the aerogel is improved, and excellent hydrophobicity is achieved through the synergistic effect of the calcium ions and methyl; the application prospect of the phenolic silicon oxide aerogel in building heat insulation is effectively promoted.

Description

Technical Field

[0001] The present invention belongs to the field of preparation processes of aerogel materials, and relates to a calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic silica aerogel material and a preparation method thereof. Background Art

[0002] As a typical porous material, aerogel has extremely low density, excellent heat insulation, good mechanical strength and extremely high specific surface area, so it has broad application prospects in many fields such as thermal insulation, adsorption, sensors, catalysis, etc. Especially phenolic silica aerogel, with its excellent stability and low thermal conductivity, has become an important research object in heat insulation materials, adsorption materials and protective materials, etc. Phenolic resin has strong thermal stability, chemical resistance and good formability. Therefore, in the preparation of aerogel materials, it is usually compounded with silica to improve its structural stability and physical properties.

[0003] However, in practical applications, the existing phenolic silica aerogel materials often face deficiencies in anti-aging performance and mechanical properties [Shi Jianjun, Yan Jiao, Kong Lei, etc. High-efficiency preparation and research of organic aerogel based on common phenolic resin [J]. Acta Polymerica Sinica, 2016, (02): 179-186]. Although the mechanical properties can be improved by surface modification or material compounding, these methods may lead to a decrease in the chemical stability of the material or a high cost during the treatment process. On the other hand, the mechanical properties of phenolic silica aerogel are usually poor, which limits its use in some application scenarios with high strength requirements. Summary of the Invention

[0004] Object of the Invention: The technical problem to be solved by the present invention is to provide a calcium ion-enhanced phenolic silica aerogel material and a preparation method thereof in view of the deficiencies of the prior art, which can significantly improve the mechanical properties and anti-aging performance of the aerogel.

[0005] In order to achieve the above object of the invention, the technical solution adopted by the present invention is as follows: A preparation method of a calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic silica aerogel material, comprising the following steps: (1) Preparation of solution A: Add phenol, aldehyde, phenolic resin, deionized water, alkaline agent, and surface activator into a container in sequence, stir and then place it in an oven for static setting to obtain solution A; (2) Take out the solution A obtained in step (1) and cool it to room temperature, add methylsilane and sodium silicate, stir evenly, and place it in an oven for static setting to obtain a wet gel; (3) Place the wet gel obtained in step (2) in a suction filtration device, and carry out low-pressure suction filtration with an aqueous calcium ion solution; (4) Aging, solvent replacement, and drying of the wet gel reinforcing material obtained in step (3) gives the product.

[0006] Specifically, in step (1), the phenol is phenol or resorcinol; the aldehyde is formaldehyde or furfural; the degree of polymerization of the phenolic resin is 500 - 2000; the basic agent is any one of anhydrous sodium carbonate, ammonia water, or triethanolamine; the surface activator is any one of cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC).

[0007] Specifically, in step (1), the phenol, aldehyde, phenolic resin, deionized water, basic agent, and surface activator are mixed in a molar ratio of x: 2x: 1 - x: 7 - 10: 0.002 - 0.008: 0.001 - 0.003; where 0.5 < x < 1.

[0008] Specifically, in step (2), the methylsilane is any one of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and trimethylethoxysilane; the modulus of the sodium silicate is 1.5 - 2.5.

[0009] Specifically, in step (2), the molar dosage ratio of the methylsilane and sodium silicate to the aldehyde in step (1) is 0.1 - 0.3: 0.05 - 0.1: 1.

[0010] Specifically, in step (3), the calcium ion aqueous solution is an aqueous solution of calcium chloride or calcium nitrate, and the mass fraction of the solute is 0.5 - 3%.

[0011] Specifically, in step (3), the pressure for suction filtration is - 5 to - 50 KPa.

[0012] Specifically, in steps (1) and (2), the oven temperature is 85 - 95 °C.

[0013] Specifically, in step (4), the wet gel aging conditions are: aging at 50 - 80 °C for 8 - 12 h, and the aging liquid is any one of ethanol, acetone, or n - hexane.

[0014] Specifically, in step (4), the drying method is any one of CO2 supercritical drying, freeze - drying, or atmospheric drying.

[0015] Furthermore, the present invention also claims protection for the integrated phenolic - silica aerogel material prepared by the above - mentioned method. Beneficial effects

[0016] (1) In the present invention, calcium ions can enhance the mechanical properties of the material through the action of their divalent positive ions between the resin and the silicate ester, improving its compressive strength and structural stability, thereby enhancing the overall mechanical properties of the aerogel. Ca²⁺ can play a crosslinking role in the composite material of phenolic resin and silica, thus improving the structural stability and compressive strength of the aerogel. In addition, calcium ions have good biocompatibility, which can improve the environmental adaptability and long-term stability of the material.

[0017] (2) In the present invention, in-situ polymerization is used to introduce hydrocarbon groups, enabling the aerogel to effectively prevent water penetration and maintain excellent water-proof performance in a wet or water-contact environment.

[0018] (3) The calcium ion source used in the present invention has a low cost and is environmentally friendly. Compared with traditional surface modification methods such as fluorination treatment, this method can effectively reduce costs while achieving hydrophobicity and enhanced performance, and has good market prospects. Description of the Drawings

[0019] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0020] Figure 1 It is a diagram of samples prepared with different calcium ion concentrations in the present invention.

[0021] Figure 2 It is a comparison of SEM of the aerogel before and after calcium ion incorporation in the present invention.

[0022] Figure 3 It is a comparison of the contact angles of the aerogel before and after aging in the present invention.

[0023] Figure 4 It is a comparison of the compressive properties of samples prepared with different calcium ion concentrations before and after aging in the present invention. Detailed Embodiments

[0024] The present invention can be better understood according to the following embodiments. Example 1

[0025] Phenol, formaldehyde, phenolic resin (degree of polymerization is 1500), and cetyltrimethylammonium bromide were mixed with deionized water and ammonia water in a molar ratio of 0.6:1.2:0.4:0.0004. 7 mL of deionized water and 0.004 mol of ammonia water were added, stirred evenly, and the mixed solution was placed in an oven at 85 °C and left standing for 4 hours to obtain a homogeneous solution. After the solution obtained in step (1) was cooled to room temperature, methyltriethoxysilane (molar ratio of 0.2) and sodium silicate (modulus 2.0, molar ratio of 0.08) were added, stirred evenly, and placed in an oven and left standing. The temperature was set at 85 °C and the reaction was carried out for 4 hours. The wet gel obtained in step (2) was placed in a suction filtration device, and an aqueous solution containing 0.5% CaCl2 was passed through. The suction filtration pressure was -7 kPa, and low-pressure suction filtration was carried out for 3 hours. The enhanced wet gel was subjected to aging treatment. The aging conditions were aging at 60 °C for 10 hours, and the aging liquid was ethanol; then solvent replacement and freeze-drying were carried out to finally obtain a calcium ion-enhanced hydrophobic phenolic silica aerogel material. Example 2

[0026] Resorcinol, furfural, phenolic resin (degree of polymerization is 1200), and cetyltrimethylammonium chloride were mixed with deionized water and triethanolamine in a molar ratio of 0.7:1.4:0.3:0.00045. 8 mL of deionized water and 0.006 mol of triethanolamine were added, stirred evenly, and the solution was placed in an oven at 80 °C and left standing for 5 hours to obtain a homogeneous solution. After the solution was cooled to room temperature, dimethyldimethoxysilane (molar ratio of 0.15) and sodium silicate (modulus 1.8, molar ratio of 0.07) were added, stirred evenly, and placed in an oven and left standing for gelation. The temperature was set at 90 °C and the reaction was carried out for 5 hours. The wet gel obtained in step (2) was placed in a suction filtration device at -20 kPa, and an aqueous solution containing 2% CaNO3 was passed through for low-pressure suction filtration. The suction filtration time was 2 hours. The wet gel was subjected to aging treatment. The aging conditions were aging at 80 °C for 8 hours, and the aging liquid was n-hexane; then atmospheric drying was carried out to obtain a calcium ion-enhanced hydrophobic phenolic silica aerogel material. Example 3

[0027] Mix resorcinol, formaldehyde, phenolic resin (degree of polymerization is 1000), and cetyltrimethylammonium bromide in a molar ratio of 0.8:1.6:0.1:0.0003 with deionized water and anhydrous sodium carbonate. Add 8 mL of deionized water and 0.003 mol of anhydrous sodium carbonate, stir well, and place the mixed solution in an oven at 90 °C for 3 hours to obtain a homogeneous solution. After the solution is cooled to room temperature, add methyltrimethoxysilane (molar ratio of 0.25) and sodium silicate (modulus 2.2, molar ratio of 0.09), stir well, and place it in the oven to stand for gelation. The temperature is set at 88 °C and the reaction lasts for 4 hours. Place the prepared wet gel in a suction filtration device, and respectively pass aqueous solutions containing 0, 0.5, 1.5, and 3% CaCl2. The suction filtration pressure is -40 kPa, and continuous suction filtration is carried out for 4 hours. The wet gel is subjected to aging treatment. The aging conditions are aging at 50 °C for 9 hours, and the aging liquid is acetone; then supercritical drying is carried out to obtain a calcium ion-enhanced hydrophobic phenolic silica aerogel material. The obtained samples are as Figure 1 shown (the calcium ion concentration increases from left to right), and the samples are subjected to compressive strength testing, hydrophobic angle testing, and anti-aging testing.

[0028] Results and performance: Conduct scanning electron microscopy testing on the sample prepared with 0.5% calcium ion content. From Figure 2 it can be seen that after calcium ion enhancement, the pore structure of the aerogel is more uniform and there is a small amount of calcium silicate enhanced network structure. As Figure 3 shown, the hydrophobic angle of the obtained sample reaches 135°, and the performance of Example 1 does not show obvious decline after being treated in a double 85 °C aging oven for one month. Conduct compressive strength testing on samples with different calcium ion concentrations and compare their performance before and after aging. As Figure 4 shown, with the increase of calcium ion concentration, the mechanical properties of the samples are significantly improved and the anti-aging performance is strong.

[0029] This preparation method successfully obtains a calcium ion-enhanced phenolic silica aerogel material with excellent hydrophobicity and mechanical properties. After testing, the contact angle of the obtained material reaches more than 130°, showing excellent hydrophobicity. The compressive strength of the material is significantly improved, and it has higher structural stability compared with conventional aerogel materials. In terms of environmental adaptability, this material shows excellent moisture resistance and high temperature resistance, and can maintain its structure and function in a humid environment for a long time.

[0030] The present invention provides an idea and method for a calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material and its preparation method. There are many methods and ways to specifically implement this technical solution. The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by using the prior art.

Claims

1. A preparation method of a calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material, characterized in that It includes the following steps: (1) Preparation of solution A: Add phenol, aldehyde, phenolic resin, deionized water, alkaline agent, and surfactant into a container in sequence. After stirring, place it in an oven and let it stand still to obtain solution A; (2) Take out the solution A in step (1) and let it cool down to room temperature. Add methylsilane and sodium silicate, stir evenly, and place it in an oven and let it stand still to obtain a wet gel; (3) Place the wet gel obtained in step (2) in a suction filtration device, and conduct low-pressure suction filtration with an aqueous calcium ion solution; (4) Age, perform solvent replacement, and dry the wet gel reinforcing material obtained in step (3) to obtain the product.

2. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that, In step (1), the phenol is phenol or resorcinol; the aldehyde is formaldehyde or furfural; the polymerization degree of the phenolic resin is 500 - 2000; the alkaline agent is any one of anhydrous sodium carbonate, ammonia water, or triethanolamine; the surfactant is any one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

3. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic silica aerogel material according to claim 1, wherein, In step (1), the phenol, aldehyde, phenolic resin, deionized water, alkaline agent, and surfactant are mixed in a molar ratio of x: 2x: 1 - x: 7 - 10: 0.002 - 0.008: 0.001 - 0.003; where 0.5 < x < 1.

4. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that, In step (2), the methylsilane is selected from any one of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and trimethylethoxysilane; the modulus of the sodium silicate is 1.5 - 2.

5.

5. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that In step (2), the molar dosage ratio of the methylsilane and sodium silicate to the aldehyde in step (1) is 0.1 - 0.3: 0.05 - 0.1:

1.

6. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that In step (3), the aqueous calcium ion solution is one of the aqueous solutions of calcium chloride or calcium nitrate, and the mass fraction of the solute is 0.5 - 3%.

7. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that In step (3), the pressure of the suction filtration is -5 to -50 KPa.

8. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that, In steps (1) and (2), the temperature of the oven is 85 - 95 °C.

9. The preparation method of the calcium ion-enhanced, heat-insulating and hydrophobic integrated phenolic aldehyde silica aerogel material according to claim 1, characterized in that In step (4), the aging conditions of the wet gel are: aging at 50 - 80 °C for 8 - 12 h, and the aging liquid is any one of ethanol, acetone, or n-hexane; the drying method is any one of CO2 supercritical drying, freeze drying, or atmospheric drying.

10. The integrated phenolic silica aerogel material prepared by the preparation method described in any one of claims 1 - 9.

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