An ultrathin thermal insulation material and a preparation method thereof

Abstract

The present application belongs to the field of new materials, and relates to an ultrathin thermal insulation material and a preparation method thereof. The present application aims at the main problems existing in the current aerogel thermal insulation products and the actual demand for high-efficiency thermal insulation products in the related field, combines the functional characteristics of nano-porous silicon, uniformly mixes SiO2 aerogel, nano-porous silicon and other functional materials with plant fibers, and obtains an environmentally-friendly and degradable new product with thermal insulation function through a papermaking process. The ultrathin thermal insulation material obtained by the present application has a thermal conductivity of less than or equal to 0.025 W / (m*K), and provides a convenient method for large-scale and continuous production of low-cost ultrathin thermal insulation materials. The present application is simple, flexible and easy to operate, and is easy to be popularized and applied.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new materials, and relates to an ultrathin thermal insulation material and a preparation method thereof. BACKGROUND

[0002] The new composite thermal insulation material mainly refers to a composite material containing a nano-porous material, and can be widely applied to fields such as electrical components, electronic products, catering packaging and new energy batteries. SiO2 aerogel has extremely low thermal conductivity, and therefore the new thermal insulation material mostly uses SiO2 aerogel as the nano-porous material. However, due to the high cost of SiO2 aerogel, its large-scale application in most fields is limited, and the use of other low-cost nano-porous materials is a potential solution. In addition, plant fiber materials have been widely applied to the thermal protection of various devices due to their light weight and low thermal conductivity. Therefore, the thermal insulation material prepared by using SiO2 aerogel and nano-porous silicon with low thermal conductivity in combination and then being compounded with plant fibers has the advantages of low cost and high efficiency, and can solve the bottleneck problem of existing aerogel products and greatly expand the market application range.

[0003] The traditional process for preparing the SiO2 aerogel / fiber composite material adopts steps such as fiber impregnation, modification and supercritical drying, and the process is relatively complex, the production cycle is long, and in the sol-gel process, the parameters such as pH value, temperature and modifier have large variability, the structure and performance of the composite material are different, and the repeatability is poor. Directly using SiO2 aerogel powder and nano-porous silicon powder as the thermal insulation material and using the wet papermaking process to combine with the fibers to form a shape can greatly shorten the preparation cycle of the thermal insulation material, and is more suitable for batch production, and can greatly reduce the production cost. The ultrathin thermal insulation material using nano-porous silicon and aerogel as the main filler has the advantages of low thermal conductivity and high cost performance, solves the bottleneck problems of high cost and low processing efficiency of the existing aerogel ultrathin thermal insulation material, and is a new type of thermal insulation product with great development prospects, which can be widely applied to the fields of food and industrial thermal insulation. SUMMARY

[0004] The purpose of the present application is to provide an ultrathin thermal insulation material and a preparation method thereof. The present application uniformly mixes SiO2 aerogel, nano-porous silicon and other functional materials with plant fibers under certain process conditions, and obtains an environmentally friendly and degradable new product with thermal insulation function through a papermaking process.

[0005] The technical scheme of the present application is as follows:

[0006] A preparation method of an ultrathin thermal insulation material, comprising the following steps:

[0007] (1) adding modifier, SiO2 aerogel powder and nano-porous silicon powder in water in sequence and performing high-speed dispersion to obtain uniform powder slurry; by using the modifier, the super-hydrophobic aerogel powder can be modified into hydrophilic type without affecting the structure and performance, thereby ensuring uniform distribution of the aerogel powder in the aqueous system;

[0008] (2) adding the powder slurry obtained in step (1) into the pre-prepared plant fiber slurry, and mixing and beating the two in a beater to make the powder material fully contact and combine with the plant fiber, thereby obtaining a fiber composite slurry; the mass percentage of SiO2 aerogel in the powder slurry is 3-5% and the mass percentage of nano-porous silicon is 30-36%; the mixing and beating process can ensure high retention rate of the nano-porous silicon and SiO2 aerogel powder in the subsequent papermaking process, and can improve the strength of the paper-based ultra-thin thermal insulation material; the plant fiber is fanned out, and the functional powder material is combined with the fiber through hydrogen bonding and embedding, thereby ensuring the strength after forming and avoiding powder dropping during use of the paper;

[0009] (3) diluting the fiber composite slurry obtained in step (2) and performing papermaking to obtain an ultra-thin thermal insulation material.

[0010] Preferably, the nano-porous silicon in step (1) has a specific surface area of ≥200 m 2 / g, a pore volume of ≥0.6 cm 3 / g, an average pore diameter of 20-30 nm and an average particle diameter of 15-25 μm; the SiO2 aerogel has a specific surface area of ≥600 m 2 / g, a pore volume of ≥0.9 cm 3 / g, an average pore diameter of 5-30 nm and an average particle diameter of 10-15 μm; the high specific surface area powder material has a more developed pore structure and a more tortuous heat transfer path, thereby greatly increasing the thermal resistance; therefore, to obtain a paper-based ultra-thin thermal insulation material with low thermal conductivity, the specific surface area of the nano-porous silicon and the aerogel powder material should be as high as possible.

[0011] Preferably, the modifier in step (1) is a surfactant or a wetting agent, such as sodium dodecyl benzene sulfonate or an organic silicon wetting agent; the amount of the modifier is 3-10% of the mass of the dry SiO2 aerogel.

[0012] Preferably, the stirring blade linear speed during the high-speed dispersion in step (1) is >12 m / s, the solid content during the dispersion is 10-40%, and the dispersion time is 20-30 min.

[0013] Preferably, the plant fiber in step (2) is conifer pulp fiber.

[0014] Preferably, the mixing beating treatment time in step (2) is 20-30 min.

[0015] Preferably, functional additives such as sizing agent, retention agent and strengthening agent can be added before dilution in step (3), the sizing agent is AKD, the retention agent is polyacrylamide, and the strengthening agent is starch.

[0016] Preferably, the dilution concentration in step (3) is 0.8-1.2%.

[0017] Preferably, the basis weight of the paper-based material prepared in step (3) is 100-200 g / m 2

[0018] Preferably, the thermal conductivity of the ultra-thin thermal insulation material obtained in step (3) is ≤0.025 W / (m·K), which can meet the use requirements.

[0019] The present application aims at the main problems existing in the current aerogel thermal insulation products and the actual demand for efficient thermal insulation products in related fields, and combines the functional characteristics of nano-porous silicon, adopts the wet papermaking process technology, adds SiO2 aerogel, nano-porous silicon and other functional materials into paper, and obtains a paper-based ultra-thin thermal insulation material with efficient thermal insulation function.

[0020] Compared with the prior art, the present application has the following technical effects:

[0021] The present application prepares a new type of ultra-thin thermal insulation material through the paper wet papermaking process, the product has a thermal conductivity of ≤0.025 W / (m·K), provides a convenient method for large-scale and continuous production of low-cost ultra-thin thermal insulation materials, fills the industry gap, and has a broad market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 SEM electron microscope photos of the combination of powder slurry and plant fibers after mixing beating treatment for example 4;

[0023] Figure 2 SEM electron microscope photos of the ultra-thin thermal insulation material after forming for example 4, wherein Figure 2 a is the material surface, Figure 2 b is the material cross section. DETAILED DESCRIPTION

[0024] The application will be further described in conjunction with specific embodiments, and the advantages and features of the application will become more apparent from the description. However, these embodiments are only exemplary, and do not constitute any limitation on the scope of the application. Those skilled in the art should understand that the details and forms of the technical solutions of the application can be modified or replaced without departing from the spirit and scope of the application, and such modifications and replacements fall within the protection scope of the application.

[0025] Example 1

[0026] A preparation method of an ultra-thin thermal insulation material

[0027] The nano-porous silicon used has the following properties: specific surface area 220 m 2 / g, pore volume 0.7 cm 3 / g, average pore diameter 25 nm, and average particle size 16 μm; the SiO2 aerogel has the following main properties: specific surface area 610 m 2 / g, pore volume 0.95 cm 3 / g, average pore diameter 12 nm, average particle size 14 μm, and the ultra-thin thermal insulation material is prepared in the following manner:

[0028] (1) 150 kg of tap water is weighed into a high-speed mixer tank, the stirring is started, 500 g of sodium hexametaphosphate and 900 g of wetting agent are added, then 10 kg of aerogel powder and 90 kg of nano-porous silicon powder are added, and the material is subjected to high-speed dispersion, and a powder slurry for papermaking and filling is obtained after uniform dispersion, wherein the linear speed of the stirring blade during high-speed dispersion is 15 m / s, the solid content of the dispersion is 20%, and the dispersion time is 30 min;

[0029] (2) the powder slurry obtained in step (1) is added to a batching tank and uniformly mixed with needle pulp fibers, and the addition amount of the powder slurry (folded dry powder) to the fibers is 34%, and the mixture is mixed and beaten for 30 min using a Valley beater;

[0030] (3) after the slurry is diluted to a concentration of 1.0%, paper is made on a small-scale test paper machine with a width of 400 mm, and an ultra-thin thermal insulation material is obtained.

[0031] The ultra-thin thermal insulation material prepared by this method has a smooth and delicate surface, no powder dropping phenomenon, and a thermal conductivity of 0.025 W / (m·K).

[0032] Example 2

[0033] A preparation method of an ultra-thin thermal insulation material

[0034] The nano-porous silicon used has the following properties: specific surface area 220 m 2 / g, pore volume 0.7 cm 3 / g, pore volume 0.95 cm 2 / g, pore volume 0.95 cm 3 / g, pore volume 0.95 cm

[0035] (1) 150 kg tap water was weighed into a high-speed mixer tank, stirring was started, 500 g sodium hexametaphosphate and 900 g wetting agent were added, then 10 kg aerogel powder and 90 kg nano-porous silicon powder were added, the material was dispersed at high speed, and a powder slurry for papermaking and filling was obtained after uniform dispersion. The linear speed of the stirring blade during high-speed dispersion was 15 m / s, the solid content of dispersion was 20%, and the dispersion time was 30 min;

[0036] (2) The powder slurry obtained in step (1) was added to the batching tank and uniformly mixed with needle pulp fibers. The filling amount of the powder slurry (folded dry powder) to the fibers was 36%, and the Vali beater was used for mixing and beating for 30 min;

[0037] (3) After diluting the slurry to a concentration of 1.0%, a small-scale test paper machine with a width of 400 mm was used to make paper, and an ultra-thin thermal insulation material was obtained.

[0038] The ultra-thin thermal insulation material prepared by this method has a smooth and delicate surface, no powder dropping phenomenon, and a thermal conductivity of 0.022 W / (m·K).

[0039] Example 3

[0040] A method for preparing an ultra-thin thermal insulation material

[0041] The nano-porous silicon used has the following properties: specific surface area 220 m 2 / g, pore volume 0.7 cm 3 / g, pore volume 0.95 cm 2 / g, pore volume 0.95 cm 3 / g, pore volume 0.95 cm

[0042] (1) 150 kg tap water was weighed into a high-speed mixer tank, stirring was started, 500 g sodium hexametaphosphate and 900 g wetting agent were added, then 10 kg aerogel powder and 90 kg nano-porous silicon powder were added, the material was dispersed at high speed, and a powder slurry for papermaking and filling was obtained after uniform dispersion. The linear speed of the stirring blade during high-speed dispersion was 15 m / s, the solid content of dispersion was 20%, and the dispersion time was 30 min;

[0043] (2) The body slurry obtained in step (1) is added to the batching tank to be uniformly mixed with the needle leaf pulp fibers, and the filling amount of the powder slurry (folded absolute dry powder) to the fibers is 38%, and the powder slurry is mixed and beaten for 30 minutes by using a Valley beater;

[0044] (3) After the slurry is diluted to a concentration of 1.0%, the ultra-thin thermal insulation material is obtained by papermaking on a small test paper machine with a width of 400 mm.

[0045] The ultra-thin thermal insulation material prepared by this method has a smooth and delicate surface, no powder dropping phenomenon, and a thermal conductivity of 0.021 W / (m·K).

[0046] Example 4

[0047] A preparation method of an ultra-thin thermal insulation material

[0048] The nano-porous silicon used has the following properties: specific surface area 350 m 2 / g, pore volume 0.8 cm 3 / g, average pore size 22 nm, and average particle size 15 μm; the main properties of the SiO2 aerogel are as follows: specific surface area 610 m 2 / g, pore volume 0.95 cm 3 / g, average pore size 12 nm, and average particle size 14 μm, and the preparation process of the ultra-thin thermal insulation material is as follows:

[0049] (1) 150 kg of tap water is weighed and added to the high-speed mixer tank, and the stirring is started. Then 500 g of sodium hexametaphosphate and 900 g of wetting agent are added, followed by 10 kg of aerogel powder and 90 kg of nano-porous silicon powder. The material is dispersed at high speed, and the powder slurry for papermaking is obtained after uniform dispersion. The stirring blade linear speed during high-speed dispersion is 15 m / s, the dispersion solid content is 20%, and the dispersion time is 30 min;

[0050] (2) The powder slurry obtained in step (1) is added to the batching tank to be uniformly mixed with the needle leaf pulp fibers, and the filling amount of the powder slurry (folded absolute dry powder) to the fibers is 40%, and the powder slurry is mixed and beaten for 30 minutes by using a Valley beater. The SEM electron microscope photos of the combination of the powder slurry and the plant fibers are as shown in Figure 1 ;

[0051] (3) After the slurry is diluted to a concentration of 1.0%, the ultra-thin thermal insulation material is obtained by papermaking on a small test paper machine with a width of 400 mm. The SEM electron microscope photos are as shown in Figure 2 ; Figure 2 a is the surface of the material, Figure 2 b is the cross section of the material.

[0052] The ultra-thin thermal insulation material prepared by the method has a smooth and delicate surface, no powder dropping phenomenon, and a thermal conductivity of 0.020 W / (m·K).

Claims

1. A method for preparing an ultra-thin thermal insulation material, characterized in that, The preparation method comprises the following steps: (1) adding modifier, SiO2 aerogel powder and nano-porous silicon powder into water in sequence, and performing high-speed dispersion to obtain uniform powder slurry; the nano-porous silicon has the following properties: specific surface area ≥ 200 m 2 / g, pore volume ≥ 0.6 cm 3 / g, average pore diameter 20-30 nm, and average particle diameter 15-25 μm; the SiO2 aerogel has the following properties: specific surface area ≥ 600 m 2 / g, pore volume ≥ 0.9 cm 3 / g, average pore diameter 5-30 nm, and average particle diameter 10-15 μm; (2) adding the powder slurry into a mold, and performing vacuum drying to obtain a porous ceramic filter element; (2) adding the powder slurry obtained in step (1) to a pre-prepared plant fiber slurry, mixing and beating the two in a beater for 20-30 min to obtain a fiber composite slurry; the plant fiber is conifer pulp fiber; the mass percentage of SiO2 aerogel to plant fiber in the powder slurry is 3-5%, and the mass percentage of nano-porous silicon to plant fiber is 30-36%; (3) diluting the fiber composite slurry obtained in step (2) to perform papermaking to obtain an ultrathin thermal insulation material; the dilution concentration is 0.8-1.2%; before dilution, a sizing agent, a retention agent and a reinforcing agent are added, the sizing agent is AKD, the retention agent is polyacrylamide, and the reinforcing agent is starch.

2. The production method according to claim 1, characterized by, In step (1), the modifier is a surfactant or a wetting agent; the amount of the modifier is 3-10% of the mass of the dry SiO2 aerogel.

3. The preparation method according to claim 1, characterized in that, In step (1), the stirring blade linear speed during high-speed dispersion is >12 m / s, the solid content during dispersion is 10-40%, and the dispersion time is 20-30 min.

4. The method of claim 1, wherein, The basis weight of the paper-based material manufactured in step (3) is 100-200 g / m 2 .

5. The preparation method according to claim 1, characterized in that, The ultrathin thermal insulation material obtained in step (3) has a thermal conductivity of ≤0.025 W / (m·K).

6. The ultrathin thermal insulation material obtained by the preparation method according to any one of claims 1-5.

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