CN102701700B - A kind of SiO2 airgel/inorganic cotton composite thermal insulation felt and its preparation method - Google Patents

Abstract

The invention relates to a _SiO2 airgel/inorganic cotton composite thermal insulation felt and a preparation method thereof. The method comprises the steps of compounding silicic acid sol and inorganic cotton, then performing aging, modification and solvent replacement treatments; and drying at normal pressure to obtain SiO ₂ airgel/inorganic cotton composite thermal insulation felt. The preparation method of the SiO _airgel /inorganic wool composite thermal insulation blanket involved in the present invention adopts cheap and easy-to-get industrial raw materials such as industrial water glass, industrial silica sol, glass wool, rock wool, mineral wool, etc., which can reduce production costs. Low cost, and the atmospheric pressure drying process is convenient and easy to operate, and is suitable for large-scale industrial production. At the same time, the product is non-toxic and harmless, and will not pollute the environment.

Description

A kind of SiO2 airgel/inorganic cotton composite thermal insulation felt and its preparation method

technical field

The invention relates to a _SiO2 airgel/inorganic cotton composite thermal insulation blanket with low density and low thermal conductivity and a preparation method thereof by normal pressure drying.

Background technique

Building energy-saving insulation materials mainly include insulation materials with polystyrene as the main raw material, such as extruded polystyrene foam board (XPS), molded polystyrene foam board (EPS), sprayed polystyrene (SPS), and Insulation materials such as polyurethane foam (PUR). However, existing thermal insulation materials such as polyphenylene and polyurethane have problems such as poor flame retardancy and dense smoke in case of fire. the

Silica (SiO ₂ ) airgel is a new type of lightweight nanoporous material with high specific surface area, high porosity and low thermal conductivity, and has excellent thermal insulation properties. In order to obtain porous SiO ₂ aerogels, the supercritical drying process was used more frequently in the past. However, the supercritical drying process requires the use of an autoclave, which is complicated, high in cost, and has certain risks. The use of atmospheric pressure drying process is more conducive to the realization of large-scale production and practical application.

At present, in order to realize the practical application of SiO ₂ airgel in the field of thermal insulation, the research of SiO ₂ airgel and fiber composite and SiO ₂ airgel cotton felt has been reported. In the literature (Industrial Textiles, 2009, 11:9-12), it is reported that the fiber mat is used as the base material and SiO ₂ airgel is composited, and the fiber mat composite SiO ₂ airgel is made of thermal insulation after surface modification and normal pressure drying. Material, the specific preparation process is: using polysiloxane as the silicon source, obtaining SiO ₂ gel through hydrolysis-polycondensation; impregnating with wet gel, making the gel penetrate into the fiber mat substrate, and obtaining fiber mat/SiO ₂ Gel complex; then aged in ethanol, soaked in hexamethyldisiloxane (oxane) for several days, modified with trimethylchlorosilane, and finally dried at 200 ° C or infrared lamp under normal pressure to obtain a hydrophobic fiber mat composite SiO ₂ airgel. National University of Defense Technology used tetraethyl orthosilicate as raw material to prepare sol, impregnated flexible fiber felt and then carried out supercritical drying to prepare flexible thermal insulation composite materials (Rare Metal Materials and Engineering, 2008, 37(suppl.2): 170-173) . J.Chandradass et al. used industrial water glass as raw material to prepare _SiO2 airgel/glass wool felt by drying under normal pressure. The raw materials and glass wool used in this document are the same as those in this patent, but the specific process links are different. Orthosilicon is used in the document. Ethyl acetate (TEOS)/SiO ₂ /ethanol solution soaks glass wool, the process is cumbersome, and the modified solution is different from this patent, the drying temperature is higher (230°C), and there is no thermal conductivity test result data (Journal of Non-Crystalline Solid, 2008, 354:4115-4119).

Utilizing the characteristics of high porosity and low thermal conductivity of SiO ₂ airgel, a new type of SiO ₂ airgel/inorganic cotton composite thermal insulation material with low thermal conductivity, excellent thermal insulation effect and fireproof performance is prepared, which will be used in thermal insulation The field of heat insulation plays a huge role, and has a wide range of application fields and good market prospects.

Contents of the invention

The object of the present invention is to provide a kind of high-efficiency thermal insulation material with clean environment protection and low thermal conductivity, which is composited by _SiO2 airgel and inorganic cotton, and to provide this _SiO2 by using cheap industrial raw materials through normal pressure drying process. A low-cost preparation method of airgel/inorganic cotton composite thermal insulation felt.

The _SiO2 airgel/inorganic cotton composite thermal insulation felt of the present invention uses cheap industrial water glass or silica sol as raw material, and prepares low thermal conductivity through a novel rapid solvent exchange/surface modification normal pressure drying process The SiO ₂ airgel/inorganic cotton composite thermal insulation blanket has a short preparation cycle and is suitable for large-scale production and commercial practical application.

_SiO of the present invention The preparation method of airgel/inorganic cotton composite thermal insulation blanket comprises the following steps:

① Preparation of silicic acid solution;

②Silicic acid sol and inorganic cotton are compounded to obtain SiO ₂ gel/inorganic cotton composite block;

③ SiO ₂ gel/inorganic cotton composite blocks are aged, modified and solvent replaced; the modifier includes organosilane and alkane reagents; Glue body;

④ The modified SiO ₂ gel/inorganic cotton composite block is dried under normal pressure to obtain a SiO ₂ airgel/inorganic cotton composite thermal insulation felt.

Among them, in the above preparation method, before the inorganic cotton is compounded with the silicic acid sol, it also includes the step of pre-coating and modifying the inorganic cotton. The specific operation steps are: calcining the original inorganic cotton at 450-500°C for 2-3 hours , cooled to room temperature, and then soaked in alumina sol, titanium oxide sol or silica sol for surface pre-coating modification. In the present invention, in order to speed up the modification speed of the composite gel block and shorten the production cycle, a pre-modifier is added to the silicic acid sol, and the pre-modifier is hexamethyldisiloxane, trimethyl Ethoxysilane, Methyltriethoxysilane or Methyltrimethoxysilane. the

In the present invention, the inorganic wool is preferably glass wool, rock wool, mineral wool or refractory fiber. Alcohols are also included in the modified solution adopted in step 3. Alcohols are preferably ethanol or isopropanol; organosilanes are preferably trimethylchlorosilane, methyltriethoxysilane, trimethylethoxysilane or a mixture of one or two or more of methyltrimethoxysilane, and the volume ratio of the modifier to the alkane reagent is about 1:0.5 to 1:1, and the alkane reagent used to clean the gel is preferably n-hexane, cyclohexane or heptane. The specific operation steps of drying in step ④ are: successively heat-preserve and dry at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 1.5-2 hours or at 50°C, 80°C, 100-120°C, At 150°C, heat-preserve and dry for 2 hours. the

In the preparation method of the present invention, the specific process of the preparation method of silicic acid solution is: first the industrial water glass of modulus=3.38 is pressed V _{industrial water glass} with deionized water: V _{deionized water} =1: 4～1: 5 Proportionally dilute, and then use strong acidic styrene cation exchange resin for ion exchange to obtain a silicic acid solution with a pH of 2-3.

In the preparation method of the present invention, the preparation method of the _SiO2 gel/inorganic cotton composite block in the step ② is: compound the silicic acid solution prepared in the step ① with the inorganic cotton in a certain proportion, and according to different Insulation performance requires the addition of different amounts of silicic acid solution.

The above-mentioned method of the present invention is further described, more specifically, the method should include the following steps:

① Preparation of alumina, titanium oxide or silica sol:

Preparation of alumina sol: Weigh a certain amount of aluminum isopropoxide, add it to a certain amount of deionized water, stir at 80°C until the aluminum isopropoxide is completely dissolved, then add an appropriate amount of concentrated nitric acid, and continue stirring for 2~ After 4 hours, the alumina sol can be obtained. The concentration of aluminum isopropoxide in the prepared alumina sol is 1.25-5 mol/L, and the concentration of concentrated nitric acid is 0.125-0.75 mol/L. the

Preparation of titanium oxide sol: use butyl titanate as titanium source, and prepare according to relevant literature on the preparation of TiO ₂ thin films by sol-gel method (Acta Silicate Sinica, 2001, 29(4): 350-354).

Preparation of silica sol: use tetraethyl orthosilicate (TEOS) as the silicon source, and prepare SiO sol with reference to the relevant literature on the preparation of SiO ₂ sol by sol-gel method (Acta Silicate Sinica, 2001, 29(4): 350-354) ; Or use industrial water glass as raw material, after obtaining silicic acid with pH=2～3 according to the above method, adjust pH=3～5 with sodium hydroxide or ammonia water to obtain silica sol; or use industrial silica sol as raw material without diluting Or dilute with deionized water according to V _{industrial silica sol} :V _{deionized water} =1:0.5～1:1 to obtain silica sol.

② Preparation of silicic acid solution:

The industrial water glass of modulus=3.38 is diluted with deionized water by V _{industrial water glass} : V _{deionized water} =1: 4～1: 5 ratio, carries out ion exchange with strongly acidic styrene cation exchange resin then, obtains pH=2 ~3 silicic acid solution.

③Pre-modified silicic acid solution:

A pre-modifier is added to the silicic acid sol, and the pre-modifier is hexamethyldisiloxane, trimethylethoxysilane, methyltriethoxysilane, and methyltrimethoxysilane. the

④Pre-coating modification of inorganic cotton: 

Calcinate the inorganic cotton at 450-500°C for 2-3 hours, cool it to room temperature, soak it in alumina sol, titanium oxide sol or silica sol, and carry out surface pre-coating modification treatment to make it fully adsorbed, and then gently Squeeze out excess alumina sol, titania sol or silica sol, put it in an oven, and dry at 100°C for 2 to 4 hours. the

⑤ Compounding of silicic acid solution and inorganic cotton to obtain _SiO2 gel/inorganic cotton composite block:

Pour the pre-modified silicic acid solution on the pretreated inorganic cotton to make it fully adsorbed, and place the inorganic cotton composite saturated with adsorbed silicic acid at 60°C to gel to obtain SiO ₂ gel/ Inorganic cotton composite block. In actual production, different amounts of silicic acid solution can be poured in according to different thermal insulation performance requirements, and the ratio of the mass (g) of inorganic cotton to the volume (ml) of silicic acid solution is 1:4-1:20.

⑥Aging and modification of SiO ₂ gel/inorganic cotton composite block:

The conditions for aging the _SiO2 gel/inorganic cotton composite block are 1 to 24 hours at 20-50°C; the _SiO2 gel/inorganic cotton composite block is subjected to solvent exchange-surface modification treatment, and the modified solution It is composed of organosilanes, alcohols and alkanes, in which organosilanes are trimethylchlorosilane or methyltriethoxysilane, alcohols are ethanol or isopropanol, or no alcohols are added, and alkanes are selected From n-hexane, cyclohexane or heptane, the volume ratio of the total organosilane modifier used to the silicic acid solution is about 1:0.8 to 1:1, and the amount of alkane solvent is just enough to immerse the _SiO2 condensate. For the glue/inorganic cotton composite block, the total modification time is 24-72 hours, which is completed in 1-3 times; after the modification is completed, the modified SiO ₂ gel/inorganic cotton composite block is cleaned with an alkane reagent.

⑦ Dry the modified SiO ₂ gel/inorganic cotton composite block under normal pressure, that is, heat preservation and drying at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 1.5h~ 2h, or heat preservation and drying at 50°C, 80°C, 100-120°C, and 150°C for 2h each to obtain SiO ₂ airgel/inorganic cotton composite thermal insulation felt.

Another object of the present invention is to provide the SiO ₂ airgel/inorganic cotton composite thermal insulation blanket prepared by any of the methods described above, which is characterized in that the density of the material is 0.10-0.30g/cm ³ , and the thermal conductivity 0.010 to 0.029 W·m ^-1 °C ^-1 .

The SiO ₂ airgel/inorganic cotton composite thermal insulation blanket described in the present invention has excellent thermal insulation properties, exhibits extremely strong hydrophobicity, and has zero water absorption, which can meet the thermal insulation requirements of building interior walls and other special requirements. The thermal insulation needs of the field; and because of its excellent flame retardant performance, it can withstand direct burning by flames for a long time, and there will be no fusing and perforation of general fiber insulation materials or fracture and fragmentation of porous mineral board insulation materials. Therefore, it has broad application prospects in the thermal insulation of building interior walls.

The preparation method of the SiO _airgel /inorganic wool composite thermal insulation blanket involved in the present invention adopts cheap and easy-to-get industrial raw materials such as industrial water glass, industrial silica sol, glass wool, rock wool, mineral wool, etc., which can reduce production costs. Low cost, and the atmospheric pressure drying process is convenient and easy to operate, and is suitable for large-scale industrial production. At the same time, the product is non-toxic and harmless, and will not pollute the environment.

Description of drawings

2 pieces of accompanying drawings of the present invention,

Fig. 1 is the SiO of embodiment _1Aerogel /glass wool composite thermal insulation blanket and its surface hydrophobicity photo, as seen from the figure, prepared _SiOAerogel /glass wool composite thermal insulation blanket presents obvious Hydrophobic, water droplets do not spread on the surface of the thermal insulation blanket, indicating that it has moisture-proof performance;

Figure 2 is a comparison diagram of pure glass wool and SiO ₂ airgel/glass wool composite thermal insulation blanket after being burned; where a is glass wool, b is SiO ₂ airgel/glass wool thermal insulation blanket. It can be seen from Figure 2 that compared with pure glass wool, the SiO ₂ airgel/glass wool composite thermal insulation felt exhibits excellent fire resistance and fire resistance, and pure glass wool can be ignited and burned; at the same time, SiO ₂ airgel/glass wool composite thermal insulation blanket is difficult to be ignited and will not burn.

Detailed ways

The following non-limiting examples can enable those skilled in the art to understand the present invention more fully, but do not limit the present invention in any way. In the following examples, unless otherwise specified, the properties of the prepared _SiO2 airgel/inorganic cotton composite thermal insulation felt were measured by the following means.

(1) Determination of density: Measure the diameter (d) and thickness (t) of the sample with a vernier caliper (4 groups for each amount, take the average value), and then calculate according to the formula V=π(d/2) ² ×t Calculate the volume of the sample; weigh the mass m of the sample with an analytical balance, and calculate the density of the sample according to the formula ρ=m/V.

(2) Determination of thermal conductivity or thermal conductivity: use a YBF3 thermal conductivity tester to measure the thermal conductivity of SiO ₂ airgel/inorganic cotton composite thermal insulation felt. The specific test process is as follows: ①First place the sample between the upper and lower copper plates of the thermal conductivity tester and fix it, and adjust the initial temperature of the thermal conductivity tester, that is, the temperature of the upper copper plate to 100°C (V _T1 ); ②Start Timing, record the temperature of the lower copper plate every 15 minutes until the temperature of the lower copper plate reaches a fixed value (V _T2 ), record this fixed value; ③Remove the sample, heat the lower copper plate to a temperature higher than the recorded temperature Stop heating at about 10°C, then record the temperature of the lower copper plate every 2 minutes, and calculate the heat dissipation rate (δT/δt) of the lower copper plate. Finally according to the formula

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 54</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; d</span>}}{{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; \&delta;T</span>}}{\mathrm{<span\; class="notranslate">\; \&delta;t</span>}}$

Calculate the thermal conductivity of the sample. the

Example 1

Preparation of SiO ₂ airgel/glass wool composite thermal insulation felt with a density of 0.23g/cm ³

① Preparation of alumina sol:

Weigh 20.4g of aluminum isopropoxide, add 200ml of deionized water and stir at 80°C until the aluminum isopropoxide is completely dissolved, then add 0.3ml of concentrated nitric acid, and continue stirring for 3 hours to form alumina sol. the

② Preparation of silicic acid solution:

Measure 60ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) and mix with 240ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid solution.

③Pre-coating treatment of glass wool: 

Put 15.531g of glass wool in a high-temperature sintering furnace and calcinate at 500°C for 2 hours, take it out and weigh 14.426g; take 50ml of the prepared alumina sol and pour it on the pre-fired glass wool to make it fully adsorbed, and then Squeeze gently to squeeze out excess alumina sol, put it in an oven, and dry it at 80°C for 2h. the

④ Compounding of silicic acid solution and glass wool:

Take 260ml of the prepared silicic acid solution and pour it on the pretreated glass wool to make it fully adsorbed, put the glass wool complex at 60°C to solidify, and obtain _SiO2 gel after gelation and aging / glass wool composite block.

⑤Aging and modification of SiO ₂ gel/glass wool composite block:

The SiO ₂ gel/glass wool composite block is modified. The modification liquid is composed of the modifier trimethylchlorosilane and the solvent n-hexane. The amount of n-hexane used in the modification process is just enough to cover the SiO ₂ gel. / glass wool composite block, the volume ratio of the total amount of modifier trimethylchlorosilane to the silicic acid solution is about 1:1, and the total time of modification treatment is 72h; The amount of modifier added for the first time is about 1/3 of the total amount, the amount of modifier added for the second time is about 1/2 of the total amount, and the amount of modifier added for the third time is about 1/3 of the total amount. About 1/6; after modification, clean the modified glass wool composite with n-hexane.

⑥ Dry the modified _SiO2 gel/glass wool composite block under normal pressure, that is, heat preservation and drying at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO2 ₂ Airgel/glass wool composite.

It has been determined that the dried SiO ₂ airgel-glass wool composite thermal insulation material has a mass of 25.973g, a volume of 112.26cm ³ , a density of 0.23g/cm ³ , and a thermal conductivity of 0.020W·m ^-1 ℃ ^{- 1} .

Example 2

Preparation of SiO ₂ airgel-inorganic cotton composite thermal insulation felt with a density of 0.23g/cm ³

1. Preparation of alumina sol: same as step 1 of Example 1;

② Preparation of silicic acid solution:

Measure 30ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) and mix with 120ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid.

③Pre-coating treatment of glass wool: 

Put 18.890g of glass wool in a high-temperature sintering furnace at 500°C for 2 hours, take it out and weigh 16.854g; take 80ml of the prepared alumina sol and pour it on the pre-fired glass wool to make it fully adsorbed, and then Squeeze gently to squeeze out excess alumina sol, then put the glass wool pretreated by alumina sol into an oven, and dry at 80°C for 2 hours. the

④ Compounding of silicic acid solution and glass wool:

Take 140ml of the prepared silicic acid solution, add 40ml of pre-modifier hexamethyldisiloxane into it, stir it evenly, pour it on the pretreated glass wool, make it fully adsorbed, and compound the glass wool The body is placed in an environment of 60° C. to make it gel, and the SiO ₂ gel/inorganic cotton composite block is obtained.

⑤Aging and modification of SiO ₂ gel/glass wool composite block:

The SiO ₂ gel/glass wool composite block is modified. The modified solution is composed of modifiers trimethylchlorosilane and n-hexane. The volume ratio of the total amount of trimethylchlorosilane to the silicic acid solution is about 1 : 0.8, the amount of n-hexane is the lowest standard to be able to cover the composite gel block; the total time of modification treatment is 48h, and the modification is carried out in two times, once every 24h, and the amount of modifier added for the first time is about It is about 1/3 of the total amount, and the amount of the second modifier added is about 2/3 of the total amount; after the modification is completed, clean the modified _SiO2 gel/glass wool composite block with n-hexane .

⑥ Dry the modified _SiO2 gel/glass wool composite block under normal pressure, that is, heat preservation and drying at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO2 ₂ Airgel/glass wool composite block.

It has been determined that the SiO ₂ airgel/glass wool composite thermal insulation blanket has a dried mass of 29.036g, a volume of 126.03cm ³ , a calculated density of 0.23g/cm ³ , and a thermal conductivity of 0.029W·m ^{- 1} °C ^-1 .

Example 3

Preparation of SiO ₂ airgel/glass wool composite thermal insulation felt with a density of 0.27g/cm ³

1. Preparation of alumina sol: same as step 1 of Example 1;

② Preparation of silicic acid solution:

Measure 40ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) and mix with 160ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid.

③Pretreatment of glass wool:

Put 16.957g of glass wool in a high-temperature sintering furnace at 500°C for 2 hours, take it out and weigh 15.846g; take 110ml of the prepared alumina sol and pour it on the pre-fired glass wool to make it fully adsorbed, and then Squeeze gently to squeeze out excess alumina sol, then put the pretreated glass wool into an oven and dry at 80°C for 2h. the

④ Compounding of silicic acid solution and glass wool:

Take 160ml of the prepared silicic acid solution, add 40ml of pre-modifier hexamethyldisiloxane, stir well and pour it on the pretreated glass wool to make it fully adsorbed, put the glass wool complex on It is gelled at 60°C to obtain a SiO ₂ gel/inorganic cotton composite block.

⑤Aging and modification of SiO ₂ gel/inorganic cotton composite block:

The _SiO2 gel/glass wool composite block is modified. The modified liquid is composed of modifier trimethylchlorosilane and n-hexane. The total amount of modifier trimethylchlorosilane and the volume of silicic acid solution The ratio is about 1:1, and the total modification time is 48 hours; the modification is carried out twice, every 24 hours. The amount of the secondary modifier added is about 2/3 of the total sol amount; after the modification is completed, the modified glass wool composite is cleaned with n-hexane.

⑥ Dry the modified gel under normal pressure, that is, heat and dry at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO ₂ airgel/glass wool composite Thermal insulation blanket.

It has been measured that the mass of the SiO ₂ airgel/glass wool composite thermal insulation blanket is 34.028g, the volume is 126.03cm ³ , the calculated density is 0.27g/cm ³ , and the thermal conductivity is 0.023W·m ^-1 ℃ ^-1 .

Example 4

Preparation of SiO ₂ airgel/glass wool composite thermal insulation felt with a density of 0.27g/cm ³

1. Preparation of alumina sol: same as step 1 of Example 1;

② Preparation of silicic acid solution:

Measure 40ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) and mix with 160ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid.

③Pretreatment of glass wool:

Put 13.306g of glass wool in a high-temperature sintering furnace at 500°C for 2 hours, take it out and weigh 12.221g; take 150ml of the prepared alumina sol and pour it on the pre-fired glass wool to make it fully adsorbed, and then Squeeze gently to squeeze out excess alumina sol, then put the pretreated inorganic cotton into an oven and dry at 80°C for 2h. the

④ Compounding of silicic acid solution and glass wool:

Take 140ml of the prepared silicic acid solution, pour it on the pretreated glass wool to make it fully adsorbed, put the glass wool composite at 60°C to make it gel, and obtain the _SiO2 gel/inorganic wool composite block body.

⑤Aging and modification of SiO ₂ gel/inorganic cotton composite block:

The SiO ₂ gel/glass wool composite block is modified. The modified solution is composed of modifier trimethylchlorosilane and n-hexane. The amount of n-hexane added during the modification process is just enough to cover the SiO ₂ Glue/glass wool composite block, the volume ratio of the total amount of modifier trimethylchlorosilane to the silicic acid solution is about 1:1, and the total modification time is 72 hours; the modification is carried out in three times, every 24 hours. Once, the amount of modifier added for the first time is about 1/3 of the volume of silicic acid, the amount of modifier added for the second time is about 1/2 of the volume of silicic acid, and the amount of modifier added for the third time is about 1/2 of the volume of silicic acid. About 1/6 of the volume; after modification, clean the modified glass wool composite with n-hexane.

⑥ Dry the modified gel under normal pressure, that is, heat and dry at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO ₂ airgel/glass wool composite Thermal insulation blanket.

It has been measured that the mass of the SiO ₂ airgel/glass wool composite thermal insulation blanket is 23.919g, the volume is 88.59cm ³ , the calculated density is 0.27g/cm ³ , and the thermal conductivity is 0.022W·m ^-1 ℃ ^-1 .

Example 5

Preparation of SiO ₂ airgel/glass wool composite thermal insulation blanket with a density of 0.19g/cm ³

1. Preparation of alumina sol: same as step 1 of Example 1;

② Preparation of silicic acid solution:

Measure 40ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) and mix with 160ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid.

③Pretreatment of glass wool:

Put 13.011g of glass wool in a high-temperature sintering furnace at 500°C for 2 hours, take it out and weigh 11.968g; take 150ml of the prepared alumina sol and pour it on the pre-fired glass wool to make it fully adsorbed, and then Squeeze gently to squeeze out excess alumina sol, then put the pretreated inorganic cotton into an oven and dry at 80°C for 2 hours. the

④ Compounding of silicic acid solution and glass wool:

Take 160ml of the prepared silicic acid solution and pour it on the pretreated glass wool to make it fully adsorbed, put the glass wool composite at 60°C to make it gel, and obtain a _SiO2 gel/inorganic wool composite block .

⑤Aging and modification of SiO ₂ gel/inorganic cotton composite block:

The SiO ₂ gel/glass wool composite block is modified. The modified solution is composed of modifier trimethylchlorosilane and n-hexane. The amount of n-hexane added during the modification process is just enough to cover the SiO ₂ Glue/glass wool composite block, the volume ratio of the total amount of modifier trimethylchlorosilane to the silicic acid solution is about 1:1, and the total modification time is 72 hours; After the glass wool composite. Concrete modification operation process is identical with embodiment 1 step ⑥.

⑥ Dry the modified gel under normal pressure, that is, heat and dry at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO ₂ airgel/glass wool composite Thermal insulation blanket.

It has been measured that the mass of the SiO ₂ airgel/glass wool composite thermal insulation blanket is 18.504g, the volume is 97.39cm ³ , the calculated density is 0.19g/cm ³ , and the thermal conductivity is 0.021W·m ^-1 ℃ ^-1 .

Example 6

Preparation of SiO ₂ airgel/glass wool composite thermal insulation felt with a density of 0.16g/cm ³

① Preparation of silicic acid solution:

Measure 60ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) and mix with 240ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid.

② Compounding of silicic acid solution and glass wool:

Take 400ml of the prepared silicic acid solution and pour it on untreated glass wool with a diameter of 13.29cm and a weight of 15.216g to make it fully adsorbed, and place the glass wool composite at 60°C to gel it. A _SiO2 gel/glass wool composite block was obtained.

③Aging and modification of SiO ₂ gel/glass wool composite block:

The _SiO2 gel/glass wool composite block is modified. The modified liquid is composed of modifier trimethylchlorosilane and n-hexane. The addition of n-hexane in the modification process is just below the _SiO2 gel. / glass wool composite block, the volume ratio of the total amount of modifier trimethylchlorosilane used and the silicic acid solution is about 1:1, and the total time of modification treatment is 72h; Glass wool composite. Concrete modification operation process is identical with embodiment 1 step ⑥.

④ Dry the modified gel under normal pressure, that is, heat and dry at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO ₂ airgel-glass wool composite body.

It has been determined that the mass of the SiO ₂ airgel-glass wool composite thermal insulation material is 38.157g, the volume is 238.48cm ³ , the calculated density is 0.16g/cm ³ , and the thermal conductivity is 0.011W·m ^-1 ℃ ^-1 .

Example 7

Preparation of SiO ₂ airgel/glass wool composite thermal insulation blanket with a density of 0.19g/cm ³

① Preparation of silicic acid solution:

Measure 10ml of industrial water glass (modulus=3.38, mSiO ₂ %=26, ρ=1.37g/ml) mixes with 40ml deionized water, carry out ion exchange by strongly acidic styrene cation exchange resin after stirring, obtain pH= 2 to 3 silicic acid.

② Compounding of silicic acid solution and glass wool:

Take 100ml of the prepared silicic acid solution and pour it on untreated glass wool with a diameter of 13.29cm and a weight of 4.672g to make it fully adsorbed, and place the glass wool composite at 60°C to gel it to obtain _SiO2 gel/glass wool composite block.

③Aging and modification of glass wool composite: 

The SiO ₂ gel/glass wool composite block is modified. The modification liquid is composed of modifier trimethylchlorosilane and n-hexane. The amount of n-hexane added during the modification process is just enough to cover the SiO ₂ gel / glass wool composite block, the volume ratio of the total amount of modifier trimethylchlorosilane to the silicic acid solution is about 1:1, and the total modification time is 72 hours; After the glass wool composite. Concrete modification operation process is identical with embodiment 1 step ⑥.

④ Dry the modified gel under normal pressure, that is, heat and dry at 50°C, 70°C, 90°C, 110°C, 130°C, and 150°C for 2 hours to obtain SiO ₂ airgel-glass wool composite body.

It has been determined that the mass of the SiO ₂ airgel-glass wool composite thermal insulation material is 13.395g, the volume is 70.50cm ³ , the calculated density is 0.19g/cm ³ , and the thermal conductivity is 0.017W·m ^-1 ℃ ^-1 .

Claims (8)

1. a SiO ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, comprises the steps:

1. silicate solution is prepared;

2. silica sol and inorganic cotton carry out compound, obtain SiO ₂gel/inorganic cotton composite block;

3. to SiO ₂gel/inorganic cotton composite block carries out ageing, and process replaced by modification and solvent; Described modifier comprises organosilan and alkanes reagent; Modified plural gel block is cleaned with alkanes reagent after completing;

4. to the SiO after modification ₂gel/inorganic cotton composite block carries out constant pressure and dry process, obtains SiO ₂aerogel/inorganic cotton compound thermal insulation felt;

Before silica sol and inorganic cotton compound, also comprise the step of silica sol being carried out to pre-modification; Described step is for join in silicate solution by HMDO;

Described step 1. in the compound method of silica sol as follows: the industrial waterglass deionized water of modulus=3.38 is pressed V _{industrial waterglass}: V _{deionized water}=1:4 ~ 1:5 dilution proportion, then carries out ion-exchange with strongly acidic styrene's cationic ion-exchange resin, obtains the silicate solution of pH=2 ~ 3.

2. SiO according to claim 1 ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, is characterized in that the inorganic cotton during described step is 2. mineral wool, rock wool, mineral wool or refractory fibre.

3. SiO according to claim 2 ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, before it is characterized in that inorganic cotton and silica sol compound, also comprises the step of inorganic cotton being carried out to pre-coated process; Described step concrete grammar is as follows: inorganic cotton is processed 2 ~ 3h by a. at 450 ~ 500 DEG C, be cooled to room temperature, b. the inorganic cotton after process is immersed in alumina sol, titanium oxide sol or silica sol, c. take out after not having completely, extrude unnecessary liquid, dry 2 ~ 4h at 100 DEG C.

4. SiO according to claim 3 ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, is characterized in that also comprising alcohols in described step modifier 3.; Described alcohols is selected from ethanol and isopropyl alcohol.

5. SiO according to claim 4 ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, the organosilan that it is characterized in that during described step is 3. is selected from one or more mixtures in trim,ethylchlorosilane, MTES, trimethylethoxysilane and MTMS; Alkanes reagent is selected from n-hexane, cyclohexane and heptane.

6. the SiO according to claim 1,3 or 5 ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, is characterized in that ageing during described step 3. for carry out 1 ~ 24h at 20 ~ 50 DEG C.

7. SiO according to claim 6 ₂the preparation method of aerogel/inorganic cotton compound thermal insulation felt, is characterized in that the concrete operation method of the drying during described step is 4. is: successively at 50 DEG C, 70 DEG C, 90 DEG C, 110 DEG C, 130 DEG C, 150 DEG C each heat preservation and dryness 1.5h ~ 2h or at 50 DEG C, 80 DEG C, 100 ~ 120 DEG C, 150 DEG C each heat preservation and dryness 2h.

8. the SiO for preparing of method according to claim 1 ₂aerogel/inorganic cotton compound thermal insulation felt, is characterized in that the density of this material is 0.10 ~ 0.30g/cm ³, thermal conductivity factor is 0.010 ~ 0.029Wm ^-1dEG C ^-1.