Preparation method for preparing thermal insulation composite material by recycling waste rock wool

Abstract

The invention discloses a preparation method for preparing a thermal insulation composite material by recycling waste rock wool, and relates to the technical field of thermal insulation materials. The thermal insulation composite material is prepared by taking regenerated fibers obtained by recycling waste rock wool as a reinforcing body and tetraethyl orthosilicate as a silicon source precursor through a sol-gel method. According to the method, the waste rock wool is recycled to prepare the regenerated fiber, so that the problems that the strength is reduced and the high-temperature stability becomes poor after the waste rock wool is recycled are effectively solved; the prepared thermal insulation composite material has the advantage of being good in thermal insulation effect, and along with addition of the regenerated fibers, the mechanical property and the infrared radiation shielding capacity in the high-temperature stage of the silicon dioxide aerogel are effectively improved. The thermal insulation composite material prepared by the invention can be prepared into various forms of thermal insulation materials. The method can be widely applied to the fields of industry, buildings, pipelines, automobiles, spaceflight and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation materials, and specifically relates to a preparation method for preparing a thermal insulation composite material by recycling waste rock wool. Background Art

[0002] Silica aerogel is the lightest solid material in the world. It is the most studied material in the field of heat insulation at present and is also a high-temperature resistant aerogel. The silica aerogel material has an extremely low thermal conductivity, which can reach 0.013 - 0.016 W / (m·K), lower than the thermal conductivity of static air (0.024 W / (m·K)), and is 2 - 3 orders of magnitude lower than that of corresponding inorganic insulating materials. Even at a high temperature of 800 °C, its thermal conductivity is only 0.043 W / (m·K). It does not decompose at high temperatures and does not emit harmful gases, belonging to a green and environmentally friendly material. However, there are still certain difficulties in directly replacing traditional thermal insulation materials with silica aerogel. There are two reasons for this: (1) The characteristics of low density and high porosity of silica aerogel lead to a sharp decline in mechanical properties; (2) Silica aerogel has strong transmittance to near-infrared thermal radiation at high temperatures, and its ability to block infrared radiation is poor at high temperature stages, resulting in a significant increase in the thermal conductivity of silica aerogel with the increase of temperature. In the prior art, the mechanical properties of the material are improved by adding heat-resistant fibers to silica aerogel.

[0003] Equipment and pipelines of enterprises such as steel, metallurgy, petrochemical, and thermal power will regularly replace thermal insulation materials, and a large amount of waste thermal insulation cotton is disassembled and stacked every year, mainly including rock wool, glass wool, and aluminum silicate wool. Among them, rock wool is mainly made from natural rocks such as basalt and gabbro, which are processed after being melted into fibers at high temperature. The maximum service temperature of rock wool is below 600 °C. Waste thermal insulation cotton usually belongs to the first category of general industrial solid waste. Due to its large volume per unit weight and large occupied area, most industrial solid waste landfills are reluctant to receive it. Direct incineration will further pollute the environment. Recycling waste thermal insulation cotton has important environmental protection significance. However, in the prior art, the recycled fibers obtained by recycling waste rock wool have problems such as reduced strength due to surface defects, influence of fiber distribution on thermal conductivity, and high-temperature stability problems, which severely limit the recycling and utilization of the materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method for preparing a thermal insulation composite material by recycling waste rock wool, and solve the following technical problems:

[0005] Existing silica aerogels have low mechanical properties due to their low density and high porosity. Moreover, silica aerogels have strong transmittance to near-infrared thermal radiation at high temperatures, and their ability to block infrared radiation is poor at high temperature stages, resulting in a significant increase in the thermal conductivity of silica aerogels as the temperature rises. When silica aerogels are directly applied in fields such as pipeline insulation, there are problems of poor mechanical properties and poor ability to block infrared radiation at high temperature stages.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A preparation method for recycling waste rock wool to prepare a thermal insulation composite material, comprising the following steps:

[0008] Mix tetraethyl orthosilicate, ethanol, water, and N,N-dimethylformamide, add hydrochloric acid to adjust the pH to 3-4, control the temperature at 45-55°C, keep the temperature for 1-2 hours, add recycled fibers and disperse evenly, add ammonia water to adjust the pH to 7-8, keep the temperature for 0.5-1 hour to obtain a gel; subject the gel to aging treatment, surface hydrophobic treatment, solvent replacement treatment, and drying treatment in sequence to obtain a thermal insulation composite material;

[0009] The preparation method of the recycled fiber comprises the following steps:

[0010] A1: Crush the recycled waste rock wool, remove binders, metal fragments, etc., perform acid washing, and high-temperature sintering to obtain recycled fibers;

[0011] A2: Mix the recycled fibers, modifier, and deionized water, control the temperature at 35-55°C, keep the temperature for 3-6 hours under stirring conditions, adjust the pH to 10-12, control the temperature at 50-60°C, keep the temperature for 2-4 hours, let it stand, filter, wash with water, and dry to obtain organic rock wool fibers;

[0012] A3: Immerse the organic rock wool fibers in a modified titanium dioxide sol, add ammonium persulfate, control the temperature at 70-80°C, keep the temperature for 3-6 hours, take out and air dry, and perform heat treatment to obtain recycled fibers.

[0013] As a further scheme of the present invention: the molar ratio of tetraethyl orthosilicate, ethanol, water, and N,N-dimethylformamide is 1:6-8:4-6:0.5-0.75.

[0014] As a further scheme of the present invention: the recycled fiber accounts for 20-40% of the total mass of the gel.

[0015] As a further scheme of the present invention: the specific steps of the aging treatment are: seal the gel with anhydrous ethanol and then seal it, and place it in an oven at 40-50°C for 24-72 hours;

[0016] The specific steps for surface hydrophobic treatment are as follows: After pouring out anhydrous ethanol, add a hexane solution of trimethyl ammonium chloride for liquid sealing, then seal and place it in an oven for treatment;

[0017] The specific steps for solvent replacement treatment are as follows: Pour out the liquid and conduct two replacement treatments with hexane, each for 2 - 12 hours;

[0018] The specific steps for drying treatment are as follows: Control the temperature at 40 - 60 °C and dry for 24 - 36 hours; raise the temperature to 70 - 80 °C and dry for 2 - 4 hours; raise the temperature to 110 - 120 °C and dry for 1 - 3 hours.

[0019] As a further scheme of the present invention: The addition ratio of recycled fiber, modifier, and deionized water in A2 is 10 g : 1 - 2 g : 100 - 1000 mL.

[0020] As a further scheme of the present invention: The preparation method of the modifier includes the following steps:

[0021] Add acrylamide, acryloyloxyethyl trimethyl ammonium chloride, and deionized water into a reaction flask and disperse evenly, adjust the pH to 6, add an azo initiator, conduct nitrogen bubbling for deoxygenation for 15 - 30 minutes, add ammonium persulfate and sodium sulfite, control the temperature at 40 - 50 °C, carry out heat preservation reaction for 2 - 4 hours, conduct suction filtration, washing, and drying to obtain the modifier.

[0022] As a further scheme of the present invention: Acrylamide accounts for 30 - 35% of the total mass of the raw materials for preparing the modifier.

[0023] As a further scheme of the present invention: Acryloyloxyethyl trimethyl ammonium chloride accounts for 30% of the total mass of the raw materials for preparing the modifier.

[0024] As a further scheme of the present invention: The azo initiator accounts for 0.001 - 0.0125% of the total mass of the raw materials for preparing the modifier.

[0025] As a further scheme of the present invention: The redox initiator is obtained by mixing ammonium persulfate and sodium sulfite with a mass ratio of 0.7 : 1; the redox initiator accounts for 0.001 - 0.0125% of the total mass of the raw materials for preparing the modifier.

[0026] As a further scheme of the present invention: The solid - liquid ratio of the organic - modified rock wool fiber and the modified titanium dioxide sol in A3 is 10 g : 20 - 100 mL; the ammonium persulfate accounts for 1 - 3% of the mass of the organic - modified rock wool fiber.

[0027] As a further scheme of the present invention: The preparation method of the modified titanium dioxide sol:

[0028] Add tetrabutyl titanate, absolute ethanol, and deionized water into a reaction flask and disperse them evenly. Add hydrochloric acid to adjust the pH to 2-3. Then add γ-aminopropyltriethoxysilane and stir for 24 h. Control the temperature at 70-80 °C and keep the reaction for 1-3 h to obtain the modified titanium dioxide sol.

[0029] As a further aspect of the present invention: The specific steps of pickling are as follows: Wash the recycled waste rock wool after impurity removal with a 1-10 wt% hydrochloric acid aqueous solution until neutral.

[0030] As a further aspect of the present invention: The diameter of the recycled fiber is 3-10 μm and the length is 1-3 mm.

[0031] Advantages of the present invention:

[0032] (1) In this application, the pickling-sintering method is used to treat the recycled waste rock wool. Hydrochloric acid is used to remove surface impurities, and high-temperature sintering treatment is carried out to reconstruct the fiber network to obtain recycled fibers. In this application, acrylamide and acryloyloxyethyltrimethylammonium chloride are used as raw materials, and a redox / azo composite initiation system is used to prepare a modifier. Utilizing the characteristic that rock wool fibers are mainly composed of acidic oxides and basic oxides, the presence of silicon dioxide and alumina in the recycled fibers makes a large number of Si-O- and Al-O- exist on the fiber surface. The positively charged H in water molecules is adsorbed by these two groups, thus making the fibers negatively charged. In this application, the surface of the recycled fibers is modified with the modifier. The cations ionized from the modifier are adsorbed on the surface of the recycled fibers through electrostatic adsorption, and the fiber surface is covered with organic matter, effectively reducing the moisture absorption rate of the fibers. Then, the fibers treated with the modifier are hydrolyzed in an alkaline water environment to obtain organically modified rock wool fibers, effectively reducing the moisture absorption of the rock wool fibers. In this application, tetrabutyl titanate is used as a precursor, hydrochloric acid is used as a catalyst, and γ-aminopropyltriethoxysilane is used as a modifier, and the sol-gel method is used to prepare the modified titanium dioxide sol. The organically modified rock wool fibers prepared in this application are immersed in the modified titanium dioxide sol. The carboxyl groups obtained by hydrolysis of the organically modified rock wool fiber surface in an alkaline water environment react with the amino groups in the modified titanium dioxide sol, so that a cross-linked coating is formed on the surface of the rock wool fiber to obtain regenerated fibers. + This application effectively solves the problem of reduced strength caused by surface defects of the regenerated fibers, and the existence of the surface coating realizes the shaped arrangement of the fibers, effectively reducing the problem of increased heat conduction paths caused by the disordered distribution of the fibers.

[0033] This application effectively solves the problem of reduced strength caused by surface defects of the regenerated fibers, and the existence of the surface coating realizes the shaped arrangement of the fibers, effectively reducing the problem of increased heat conduction paths caused by the disordered distribution of the fibers.

[0034] (2) In the process of preparing silica sol by the sol-gel method in this application, recycled fibers are added and processed subsequently to obtain a thermal insulation composite material with a good pore structure. The regenerated fibers prepared in this application are blended with silica aerogel, so that the composite material has certain mechanical properties and an insulating effect of preventing infrared radiation from passing through.

[0035] This application conducts organic modification and coating treatment on the surface of recycled rock wool fibers. Among them, through organic modification, the dispersibility and interfacial bonding strength of the fibers are effectively improved. The recycled fibers prepared in this application can be evenly dispersed in the aerogel matrix and overlap with each other, firmly bonded to the surrounding silica aerogel matrix, play a supporting role for the aerogel, effectively prevent its shrinkage, collapse and cracking, and can also improve the toughness of the material, forming a complete material with multiple voids and a certain strength. This application utilizes the advantages of the high-temperature stability and low thermal conductivity of recycled fibers to effectively improve the high-temperature stability, heat insulation performance and mechanical strength of aerogels. Through coating treatment, the coating has infrared reflection performance, which not only effectively reduces the penetrability of infrared electromagnetic waves that transmit heat radiation energy at high temperatures, avoids the increase of radiative thermal conductivity with the increase of temperature, and improves the anti-infrared radiation ability of silica aerogels.

[0036] The thermal insulation composite material prepared in this application combines recycled fibers and aerogels well, regulates the porosity of aerogels and the fiber distribution density to achieve synergistic heat insulation, enhances the mechanical properties of the composite material while ensuring a low thermal conductivity, and enables it to play a great role in the field of thermal insulation. Specific Embodiments

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely 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 making creative efforts belong to the scope of protection of the present invention.

[0038] The preparation method of the recycled fibers in Example 1 includes the following steps:

[0039] A1: Crush the recycled waste rock wool, remove binders, metal fragments, etc., wash the recycled waste rock wool after impurity removal with 4wt% hydrochloric acid aqueous solution until neutral, and sinter at 800°C for 2h to obtain recycled fibers with a diameter of 3 - 10μm and a length of 1 - 3mm;

[0040] A2: Add 30g of acrylamide, 30g of acryloyloxyethyltrimethylammonium chloride, and 39.99mL of deionized water into a reaction flask and disperse evenly, adjust the pH to 6, add 0.01g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (VA-044), purge with nitrogen for 30min to remove oxygen, add 0.007g of ammonium persulfate and 0.003g of sodium formaldehyde sulfoxylate, keep the temperature at 30°C for 2h, and dry to obtain a modifier;

[0041] A3: Blend 10 g of recycled fibers, 1 g of modifier, and 100 mL of deionized water. Control the temperature at 35 °C and keep the mixture under stirring for 3 h. Adjust the pH to 10, control the temperature at 50 °C, and keep the reaction for 2 h. Let it stand, filter, wash with water, and dry to obtain organic rock wool fibers.

[0042] A4: Add 10 mL of tetrabutyl titanate, 10 mL of deionized water, and 70 mL of absolute ethanol into a reaction flask and disperse evenly. Add 36 wt% hydrochloric acid to adjust the pH to 2. Add 0.5 mL of γ-aminopropyltriethoxysilane and stir for 24 h. Control the temperature at 70 °C and keep the reaction for 1 h to obtain modified titanium dioxide sol.

[0043] A5: Immerse 10 g of organic rock wool fibers into 50 mL of modified titanium dioxide sol. Add 0.2 g of ammonium persulfate, control the temperature at 70 °C, and keep the reaction for 3 h. Take it out, dry in the air, and perform heat treatment to obtain recycled fibers.

[0044] The preparation method of the recycled fibers in Example 2 includes the following steps:

[0045] A1: Crush the recycled waste rock wool, remove the binder, metal fragments, etc. Wash the recycled waste rock wool after impurity removal with 4 wt% hydrochloric acid aqueous solution until neutral, and sinter at 800 °C for 2 h to obtain recycled fibers with a diameter of 3 - 10 μm and a length of 1 - 3 mm.

[0046] A2: Add 33 g of acrylamide, 30 g of acryloyloxyethyltrimethylammonium chloride, and 36.99 mL of deionized water into a reaction flask and disperse evenly. Adjust the pH to 6. Add 0.01 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (VA-044), purge with nitrogen for 30 min to remove oxygen. Add 0.007 g of ammonium persulfate and 0.003 g of sodium formaldehyde sulfoxylate, and keep the reaction at 30 °C for 2 h. Dry to obtain the modifier.

[0047] A3: Blend 10 g of recycled fibers, 1.5 g of modifier, and 200 mL of deionized water. Control the temperature at 45 °C and keep the mixture under stirring for 4 h. Adjust the pH to 11, control the temperature at 55 °C, and keep the reaction for 3 h. Let it stand, filter, wash with water, and dry to obtain organic rock wool fibers.

[0048] A4: Add 10 mL of tetrabutyl titanate, 10 mL of deionized water, and 70 mL of absolute ethanol into a reaction flask and disperse evenly. Add 36 wt% hydrochloric acid to adjust the pH to 2. Add 1 mL of γ-aminopropyltriethoxysilane and stir for 24 h. Control the temperature at 75 °C and keep the reaction for 2 h to obtain modified titanium dioxide sol.

[0049] A5: Immerse 10 g of organically modified rock wool fibers in 50 mL of modified titanium dioxide sol, add 0.2 g of ammonium persulfate, control the temperature at 75 °C, keep the temperature for reaction for 4 h, take out and air-dry, then conduct heat treatment to obtain regenerated fibers.

[0050] The preparation method of the regenerated fibers in Example 3 includes the following steps:

[0051] A1: Crush the recycled waste rock wool, remove binders, metal fragments, etc. Wash the recycled waste rock wool after impurity removal with 4 wt% hydrochloric acid aqueous solution until neutral, and sinter at 800 °C for 2 h to obtain recycled fibers with a diameter of 3 - 10 μm and a length of 1 - 3 mm.

[0052] A2: Add 35 g of acrylamide, 30 g of acryloyloxyethyltrimethylammonium chloride, and 34.99 mL of deionized water into a reaction flask and disperse evenly. Adjust the pH to 6, add 0.01 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (VA - 044), purge with nitrogen for 30 min to remove oxygen, add 0.007 g of ammonium persulfate and 0.003 g of sodium formaldehyde sulfoxylate, keep the temperature at 30 °C for reaction for 2 h, and then dry to obtain a modifier.

[0053] A3: Blend 10 g of recycled fibers, 2 g of modifier, and 1000 mL of deionized water, control the temperature at 55 °C, keep the temperature for reaction for 6 h under stirring conditions, adjust the pH to 12, control the temperature at 60 °C, keep the temperature for reaction for 4 h, then let it stand, filter, wash with water, and dry to obtain organically modified rock wool fibers.

[0054] A4: Add 10 mL of tetrabutyl titanate, 10 mL of deionized water, and 70 mL of absolute ethanol into a reaction flask and disperse evenly. Add 36 wt% hydrochloric acid to adjust the pH to 2, add 1.5 mL of γ-aminopropyltriethoxysilane, stir for 24 h, control the temperature at 80 °C, keep the temperature for reaction for 3 h to obtain modified titanium dioxide sol.

[0055] A5: Immerse 10 g of organically modified rock wool fibers in 50 mL of modified titanium dioxide sol, add 0.2 g of ammonium persulfate, control the temperature at 80 °C, keep the temperature for reaction for 6 h, take out and air-dry, then conduct heat treatment to obtain regenerated fibers.

[0056] Example 4 A preparation method of a heat-insulating composite material prepared from recycled waste rock wool includes the following steps:

[0057] S1: Blend 100 g of tetraethyl orthosilicate, 138 g of ethanol, 40.7 mL of water, and 20.3 g of N,N-dimethylformamide, add hydrochloric acid to adjust the pH to 3, control the temperature at 50 °C, keep the temperature for reaction for 1.5 h, add the regenerated fibers prepared in Example 1 and disperse evenly, add ammonia water to adjust the pH to 7, keep the temperature for reaction for 0.5 h, and the regenerated fibers account for 30% of the total mass of the gel to obtain a gel.

[0058] S2: Aging treatment: After sealing the gel with anhydrous ethanol, place it in an oven and age it at 50°C for 48 h.

[0059] S3: Surface hydrophobic treatment: Pour out the anhydrous ethanol in the gel after aging treatment, add a n - hexane solution of 10 vt% trimethylammonium chloride for liquid sealing and then seal it, and place it in an oven at 25°C for 24 h.

[0060] S4: Solvent replacement treatment: Pour out the liquid in the gel after surface hydrophobic treatment, and perform two replacement treatments with n - hexane, 2 h each time.

[0061] S5: Drying treatment: Place the gel after solvent replacement treatment in an oven, control the temperature at 60°C and dry for 24 h; raise the temperature to 80°C and dry for 2 h; raise the temperature to 120°C and dry for 1 h to obtain the thermal insulation composite material.

[0062] Example 5 A preparation method of a thermal insulation composite material prepared from recycled waste rock wool, comprising the following steps:

[0063] S1: Blend 100 g of tetraethyl orthosilicate, 138 g of ethanol, 40.7 mL of water, and 20.3 g of N,N - dimethylformamide, add hydrochloric acid to adjust the pH to 3, control the temperature at 50°C, hold the reaction for 1.5 h, add the recycled fiber prepared in Example 2 and disperse it evenly, add ammonia water to adjust the pH to 7, hold the reaction for 0.5 h, and the recycled fiber accounts for 30% of the total mass of the gel to obtain the gel.

[0064] S2: Aging treatment: After sealing the gel with anhydrous ethanol, place it in an oven and age it at 50°C for 48 h.

[0065] S3: Surface hydrophobic treatment: Pour out the anhydrous ethanol in the gel after aging treatment, add a n - hexane solution of 10 vt% trimethylammonium chloride for liquid sealing and then seal it, and place it in an oven at 25°C for 24 h.

[0066] S4: Solvent replacement treatment: Pour out the liquid in the gel after surface hydrophobic treatment, and perform two replacement treatments with n - hexane, 2 h each time.

[0067] S5: Drying treatment: Place the gel after solvent replacement treatment in an oven, control the temperature at 60°C and dry for 24 h; raise the temperature to 80°C and dry for 2 h; raise the temperature to 120°C and dry for 1 h to obtain the thermal insulation composite material.

[0068] Example 6 A preparation method of a thermal insulation composite material prepared from recycled waste rock wool, comprising the following steps:

[0069] S1: Blend 100 g of tetraethyl orthosilicate, 138 g of ethanol, 40.7 mL of water, and 20.3 g of N,N-dimethylformamide. Add hydrochloric acid to adjust the pH to 3, control the temperature at 50 °C, and keep the reaction for 1.5 h. Add the regenerated fibers prepared in Example 3 and mix evenly. Then add ammonia water to adjust the pH to 7 and keep the reaction for 0.5 h. The regenerated fibers account for 30% of the total mass of the gel to obtain the gel.

[0070] S2: Aging treatment: After sealing the gel with anhydrous ethanol for liquid sealing, place it in an oven and age it at 50 °C for 48 h.

[0071] S3: Surface hydrophobic treatment: Pour out the anhydrous ethanol in the gel after aging treatment, add a n-hexane solution of 10 vt% trimethylammonium chloride for liquid sealing and then seal it. Place it in an oven and treat it at 25 °C for 24 h.

[0072] S4: Solvent replacement treatment: Pour out the liquid in the gel after surface hydrophobic treatment, and perform two replacement treatments with n-hexane, 2 h each time.

[0073] S5: Drying treatment: Place the gel after solvent replacement treatment in an oven, control the temperature at 60 °C and dry for 24 h; raise the temperature to 80 °C and dry for 2 h; raise the temperature to 120 °C and dry for 1 h to obtain the thermal insulation composite material.

[0074] The preparation method of the regenerated fibers in Comparative Example 1 includes the following steps:

[0075] A1: Crush the recycled waste rock wool, remove the binder, metal fragments, etc. Wash the recycled waste rock wool after impurity removal with a 4 wt% hydrochloric acid aqueous solution until neutral, and sinter it at 800 °C for 2 h to obtain recycled fibers with a diameter of 3 - 10 μm and a length of 1 - 3 mm.

[0076] A2: Add 10 mL of tetrabutyl titanate, 10 mL of deionized water, and 70 mL of anhydrous ethanol into a reaction flask and mix evenly. Add 36 wt% hydrochloric acid to adjust the pH to 2, add 1 mL of γ-aminopropyltriethoxysilane, stir for 24 h, control the temperature at 75 °C, and keep the reaction for 2 h to obtain the modified titanium dioxide sol.

[0077] A3: Immerse 10 g of organically modified rock wool fibers into 50 mL of the modified titanium dioxide sol, add 0.2 g of ammonium persulfate, control the temperature at 75 °C, and keep the reaction for 4 h. Take it out, dry it in the air, and perform heat treatment to obtain the regenerated fibers.

[0078] The preparation method of the regenerated fibers in Comparative Example 2 includes the following steps:

[0079] A1: Crush the recycled waste rock wool, remove the binder, metal fragments, etc. Wash the recycled waste rock wool after impurity removal with 4 wt% hydrochloric acid aqueous solution until neutral, and sinter it at 800 °C for 2 h to obtain recycled fibers with a diameter of 3 - 10 μm and a length of 1 - 3 mm;

[0080] A2: Add 33 g of acrylamide, 30 g of acryloyloxyethyltrimethylammonium chloride, and 36.99 mL of deionized water into a reaction flask and disperse evenly. Adjust the pH to 6, add 0.01 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (VA - 044), purge with nitrogen for 30 min to remove oxygen, add 0.007 g of ammonium persulfate and 0.003 g of sodium formaldehyde sulfoxylate, keep the temperature at 30 °C and react for 2 h, then dry to obtain the modifier;

[0081] A3: Blend 10 g of recycled fibers, 1.5 g of modifier, and 200 mL of deionized water, control the temperature at 45 °C, keep the temperature and react for 4 h under stirring conditions, then let it stand, filter, wash with water, and dry to obtain organic rock wool fibers;

[0082] A4: Add 10 mL of tetrabutyl titanate, 10 mL of deionized water, and 70 mL of absolute ethanol into a reaction flask and disperse evenly. Add 36 wt% hydrochloric acid to adjust the pH to 2, add 1 mL of γ-aminopropyltriethoxysilane, stir for 24 h, control the temperature at 75 °C, and keep the temperature and react for 2 h to obtain the modified titanium dioxide sol;

[0083] A5: Immerse 10 g of organic rock wool fibers into 50 mL of the modified titanium dioxide sol, add 0.2 g of ammonium persulfate, control the temperature at 75 °C, keep the temperature and react for 4 h, take out and air-dry, then perform heat treatment to obtain the regenerated fibers.

[0084] The preparation method of the regenerated fibers in Comparative Example 3 includes the following steps:

[0085] A1: Crush the recycled waste rock wool, remove the binder, metal fragments, etc. Wash the recycled waste rock wool after impurity removal with 4 wt% hydrochloric acid aqueous solution until neutral, and sinter it at 800 °C for 2 h to obtain recycled fibers with a diameter of 3 - 10 μm and a length of 1 - 3 mm;

[0086] A2: Add 33 g of acrylamide, 30 g of acryloyloxyethyltrimethylammonium chloride, and 36.99 mL of deionized water into a reaction flask and disperse evenly. Adjust the pH to 6, add 0.01 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (VA - 044), purge with nitrogen for 30 min to remove oxygen, add 0.007 g of ammonium persulfate and 0.003 g of sodium formaldehyde sulfoxylate, keep the temperature at 30 °C and react for 2 h, then dry to obtain the modifier;

[0087] A3: Blend 10 g of recycled fibers, 1.5 g of modifier, and 200 mL of deionized water, control the temperature at 45 °C, keep the reaction under stirring for 4 h, adjust the pH to 11, control the temperature at 55 °C, keep the reaction for 3 h, let it stand, filter, wash with water, and dry to obtain organic rock wool fibers;

[0088] A4: Add 2.35 g of nano-titanium dioxide, 10 mL of deionized water, and 70 mL of absolute ethanol into a reaction flask and disperse evenly. Add 1 mL of γ-aminopropyltriethoxysilane, stir for 24 h, control the temperature at 75 °C, keep the reaction for 2 h to obtain a modified titanium dioxide solution;

[0089] A5: Immerse 10 g of organic rock wool fibers into 50 mL of the modified titanium dioxide solution, add 0.2 g of ammonium persulfate, control the temperature at 75 °C, keep the reaction for 4 h, take out and air dry, then perform heat treatment to obtain regenerated fibers.

[0090] The preparation method of the regenerated fibers in Comparative Example 4 includes the following steps:

[0091] A1: Crush the recycled waste rock wool, remove binders, metal fragments, etc. Wash the recycled waste rock wool after impurity removal with 4 wt% hydrochloric acid aqueous solution until neutral, and sinter at 800 °C for 2 h to obtain recycled fibers with a diameter of 3 - 10 μm and a length of 1 - 3 mm;

[0092] A2: Add 33 g of acrylamide, 30 g of acryloyloxyethyltrimethylammonium chloride, and 36.99 mL of deionized water into a reaction flask and disperse evenly. Adjust the pH to 6, add 0.01 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (VA - 044), purge with nitrogen for 30 min to remove oxygen, add 0.007 g of ammonium persulfate and 0.003 g of sodium formaldehyde sulfoxylate, keep the reaction at 30 °C for 2 h, and dry to obtain a modifier;

[0093] A3: Blend 10 g of recycled fibers, 1.5 g of modifier, and 200 mL of deionized water, control the temperature at 45 °C, keep the reaction under stirring for 4 h, adjust the pH to 11, control the temperature at 55 °C, keep the reaction for 3 h, let it stand, filter, wash with water, and dry to obtain regenerated fibers.

[0094] Comparative Example 5 is compared with Example 5. Only the regenerated fibers prepared in Example 2 used in Example 5 are replaced with the regenerated fibers prepared in Comparative Example 1 in equal amounts, and the other components and preparation methods are exactly the same as those in Example 5.

[0095] Comparative Example 6 is compared with Example 5. Only the regenerated fibers prepared in Example 2 used in Example 5 are replaced with the regenerated fibers prepared in Comparative Example 2 in equal amounts, and the other components and preparation methods are exactly the same as those in Example 5.

[0096] Comparative Example 7 is compared with Example 5. Only the regenerated fiber prepared in Example 2 used in Example 5 is equivalently replaced with the regenerated fiber prepared in Comparative Example 3, and the other components and preparation methods are exactly the same as those in Example 5.

[0097] Comparative Example 8 is compared with Example 5. Only the regenerated fiber prepared in Example 2 used in Example 5 is equivalently replaced with the regenerated fiber prepared in Comparative Example 4, and the other components and preparation methods are exactly the same as those in Example 5.

[0098] Performance Testing

[0099] (1) Thermal conductivity: According to GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Guarded Hot Plate Method", the thermal conductivity at 25 °C was tested, and the test results are shown in Table 1;

[0100] (2) High-temperature thermal conductivity: According to YB / T 4130-2005 "Test Method for Thermal Conductivity of Refractory Materials (Water Flow Flat Plate Method)", the thermal conductivity at 200 °C was tested, and the test results are shown in Table 1;

[0101] (3) Mechanical properties: According to GB / T 13480-2014 "Determination of Compressive Properties of Thermal Insulation Products for Building Applications", the test results are shown in Table 1;

[0102] (4) Density determination: The material density ρ is calculated according to the following formula:

[0103] ρ = m / v

[0104] In the formula, ρ - sample density, g / cm 3 ; m - mass of the sample, g; v - volume of the sample, cm 3 ;

[0105] (5) Contact angle: The static contact angle on the surface of the sample was detected using a surface tension / dynamic contact angle measuring instrument (3 μL water droplet was dropped on the horizontal plane of the sample), and the test results are shown in Table 1;

[0106] Table 1: Statistical Table of Performance Testing Data for Examples 4-6 and Comparative Examples 5-8

[0107]

[0108] As can be seen from Table 1, the regenerated fiber prepared in this application is added during the preparation of silica aerogel to obtain a thermal insulation composite material; the regenerated fiber added in this application has been organically treated and its surface has been treated with modified silica sol, effectively reducing the hygroscopicity of rock wool fiber; moreover, the thermal insulation composite material has undergone hydrophobic surface treatment during subsequent processing, further improving the hydrophobic performance of the material, and the contact angle of the thermal insulation composite material prepared in this application is as high as over 125°.

[0109] In this application, regenerated fibers are added to silica aerogel. The organic cross-linking of the regenerated fibers and the aerogel enables the regenerated fibers to be evenly dispersed in the aerogel matrix and overlap with each other, providing a supporting effect on the aerogel, effectively preventing its shrinkage, collapse, and cracking, and forming a complete material with multiple voids and a certain strength. In this application, the recycled rock wool fibers are treated with a modified titanium dioxide sol to obtain regenerated fibers with a surface coating treatment, effectively reducing the radiative heat conduction of the material in a high-temperature environment.

[0110] The above has described in detail an embodiment of the present invention, but the content described is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A preparation method for recycling waste rock wool to prepare a thermal insulation composite material, characterized in that, It includes the following steps: Mix tetraethyl orthosilicate, ethanol, water, and N,N-dimethylformamide, add hydrochloric acid to adjust the pH to 3 - 4, control the temperature at 45 - 55°C, keep warm and react for 1 - 2 h, add regenerated fiber and disperse evenly, add ammonia water to adjust the pH to 7 - 8, keep warm and react for 0.5 - 1 h to obtain a gel; subject the gel to aging treatment, surface hydrophobic treatment, solvent replacement treatment, and drying treatment in sequence to obtain a thermal insulation composite material; The preparation method of the regenerated fiber includes the following steps: A1: Crush, remove impurities, pickle, and perform high-temperature sintering on the recycled waste rock wool to obtain recycled fiber; A2: Mix the recycled fiber, modifier, and deionized water, control the temperature at 35 - 55°C, keep warm and react for 3 - 6 h under stirring conditions, adjust the pH to 10 - 12, control the temperature at 50 - 60°C, keep warm and react for 2 - 4 h, let it stand, filter, wash with water, and dry to obtain organically modified rock wool fiber; A3: Immerse the organically modified rock wool fiber in the modified titanium dioxide sol, add ammonium persulfate, control the temperature at 70 - 80°C, keep warm and react for 3 - 6 h, take it out, air dry, and perform heat treatment to obtain the regenerated fiber.

2. The preparation method of a thermal insulation composite material prepared by recycling waste rock wool according to claim 1, characterized in that, The molar ratio of tetraethyl orthosilicate, ethanol, water, and N,N-dimethylformamide is 1:6 - 8:4 - 6:0.5 - 0.

75.

3. The preparation method of a thermal insulation composite material prepared by recycling waste rock wool according to claim 1, characterized in that, The regenerated fiber accounts for 20 - 40% of the total mass of the gel.

4. According to the preparation method of a thermal insulation composite material prepared from recycled waste rock wool as described in claim 1, characterized in that The specific steps of the aging treatment are: seal the gel with anhydrous ethanol and then seal it, and place it in an oven at 40 - 50°C for 24 - 72 h; The specific steps of the surface hydrophobic treatment are: pour out the anhydrous ethanol, add a n-hexane solution of trimethylammonium chloride for liquid sealing and then seal it, and place it in an oven for treatment; The specific steps of the solvent replacement treatment are: pour out the liquid, and perform two replacement treatments with n-hexane, each for 2 - 12 h; The specific steps of the drying treatment are: control the temperature at 40 - 60°C and dry for 24 - 36 h; raise the temperature to 70 - 80°C and dry for 2 - 4 h; raise the temperature to 110 - 120°C and dry for 1 - 3 h.

5. The preparation method of a heat-insulating composite material prepared by recycling waste rock wool according to claim 1, characterized in that, In A2, the addition ratio of the recycled fiber, modifier, and deionized water is 10 g:1 - 2 g:100 - 1000 mL.

6. The preparation method of a thermal insulation composite material prepared by recycling waste rock wool according to claim 1, characterized in that, The preparation method of the modifier includes the following steps: Add acrylamide, acryloyloxyethyltrimethylammonium chloride, and deionized water into a reaction flask and disperse evenly, adjust the pH to 6, add an azo initiator, purge with nitrogen to remove oxygen for 15 - 30 min, add ammonium persulfate and sodium sulfite, control the temperature at 40 - 50°C, keep warm and react for 2 - 4 h, perform suction filtration, washing, and drying to obtain the modifier.

7. The preparation method of a thermal insulation composite material prepared by recycling waste rock wool according to claim 1, characterized in that, In A3, the solid-liquid ratio of the organically modified rock wool fiber to the modified titanium dioxide sol is 10 g:20 - 100 mL; the ammonium persulfate accounts for 1 - 3% of the mass of the organically modified rock wool fiber.

8. The preparation method of a thermal insulation composite material prepared by recycling waste rock wool according to claim 1, characterized in that, The preparation method of the modified titanium dioxide sol: Add tetrabutyl titanate and absolute ethanol into a reaction flask and disperse them evenly. After mixing deionized water, hydrochloric acid and absolute ethanol together, add the mixture into the reaction flask and disperse it evenly. Then add γ-aminopropyltriethoxysilane and stir for 24 h. Control the temperature at 70-80 °C and keep the reaction for 1-3 h to obtain the modified titanium dioxide sol.

9. The preparation method of a heat-insulating composite material prepared by recycling waste rock wool according to claim 1, characterized in that, The specific steps of the pickling are as follows: Wash the recycled waste rock wool after impurity removal with a 1-10 wt% hydrochloric acid aqueous solution until it is neutral.

10. The preparation method of a thermal insulation composite material prepared by recycling waste rock wool according to claim 1, characterized in that, The diameter of the recycled fiber is 3-10 μm and the length is 1-3 mm.

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