CN111018494B

CN111018494B - Nano-pore heat insulation material and preparation method thereof

Info

Publication number: CN111018494B
Application number: CN201911324816.9A
Authority: CN
Inventors: 张世超; 孙现凯; 方凯; 孙浩然; 陈玉峰; 胡利明; 王�华; 艾兵; 陶柳实; 闫达琛
Original assignee: China Building Materials Academy CBMA
Current assignee: China Building Materials Academy CBMA
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2022-02-15
Anticipated expiration: 2039-12-20
Also published as: CN111018494A

Abstract

The invention relates to a nanopore heat insulation material and a preparation method thereof, wherein the preparation method comprises the following steps: diluting 5-30 parts by weight of thermosetting resin with water or absolute ethyl alcohol until the solid phase content is 10-40 wt%; mixing and stirring the obtained thermosetting resin diluent, 20-90 parts by weight of nano powder and 2-30 parts by weight of opacifier uniformly; uniformly mixing 10-80 parts by weight of polyurethane foam and the obtained particles under the condition of high-speed stirring; pouring the obtained sticky particles into a mould for molding; drying the obtained block; and taking the dried material out of the mold and carbonizing the dried material under the condition of vacuum or inert atmosphere. The heat insulating material of the present invention has carbonaceous closed pores to coat the nanometer powder, and has the highest use temperature of 1200 deg.c, which is 1 time higher than that of common silica aerogel product.

Description

Nano-pore heat insulation material and preparation method thereof

Technical Field

The invention belongs to the technical field of heat insulation and heat preservation materials, and particularly relates to a nano-pore heat insulation material and a preparation method thereof.

Background

Energy conservation and emission reduction are important research subjects in the world, and the use of high-efficiency heat insulation materials is one of key measures for energy conservation and emission reduction. The super heat-insulating material represented by aerogel is expected to be widely used in heat-insulating engineering in the industrial field due to excellent heat-insulating and heat-preserving performance, but the material needs supercritical drying to prevent the material from shrinking in the manufacturing process, and the manufacturing process brings higher manufacturing cost. And the relatively low strength of such materials also becomes a key limiting factor in their use.

Related researches in China and related products aim to solve the problem of strength, the strength of the aerogel is improved by adding a large amount of fibers or adhesives, the aerogel added with a large amount of fibers is very easy to be pulverized and slag is easy to fall, and the aerogel is difficult to be machined into complex shapes in practical application. The application temperature of most of the aerogel products in the current market is below 650 ℃, which is mainly because the reinforced fibers are glass fibers and cannot meet the working occasions requiring high-efficiency heat insulation at higher temperature.

Disclosure of Invention

In view of the above, the present invention provides a nanoporous thermal insulation material and a method for preparing the same, wherein the nanoporous thermal insulation material is prepared by mixing organic polyurethane foam, thermosetting resin, inorganic nanopowder particles and an opacifier and carbonizing the mixture at a high temperature.

In order to achieve the above object, the present invention provides a method for preparing a nanopore thermal insulation material, comprising the steps of:

1) diluting 5-30 parts by weight of thermosetting resin with water or absolute ethyl alcohol until the solid phase content is 10-40 wt%;

2) mixing and stirring uniformly the thermosetting resin diluent obtained in the step 1), 20-90 parts by weight of nano powder and 2-30 parts by weight of opacifier;

3) uniformly mixing 10-80 parts by weight of polyurethane foam and the particles obtained in the step 2) under a high-speed stirring condition;

4) pouring the sticky particles obtained in the step 3) into a mould for molding;

5) drying the block obtained in the step 4);

6) taking the material dried in the step 5) out of the mold, and carbonizing under the condition of vacuum or inert atmosphere to obtain the nanopore heat insulation material.

Further, in the step 1), the thermosetting resin is selected from phenolic resin or epoxy resin, and the carbonized carbon residue rate of the resin is high.

Further, in the step 2), the rotation speed of the mixing and stirring is 500-; the preferred rotation speed is 1000-2000 rpm, the time is 6-10 minutes, and the uniform mixing can be realized in a short time.

Further, in the step 2), the nano powder is selected from aerogel powder or white carbon black powder with a nano pore structure, and the size of the nano pore structure is less than 500 nanometers.

Further, in step 2), the opacifier includes at least one of titanium oxide, silicon carbide, zirconium oxide and graphite, which is powder with high reflectivity.

Further, in the step 2), the particle size of the opacifier is 0.3-100 microns, preferably 0.3-10 microns, and preferably, the rear shading effect is better.

Further, in the step 3), the rotation speed of the high-speed stirring is 500-; the preferred rotation speed is 3000-6000/min, the time is 6-100 min, and the uniform mixing can be realized in a short time.

Further wherein in step 3), the polyurethane foam is prepared by the steps of:

stirring 30-70 wt% of polyether polyol, 40-60 wt% of isocyanate, 1-3 wt% of catalyst, 1-4 wt% of surfactant and 2-8 wt% of water at a high speed of 500-3000 r/min for 5-60 min to obtain the polyurethane foam.

Further preferably, wherein in step 3), the polyurethane foam is prepared by the following steps:

stirring 40-50 wt% of polyether polyol, 50-55 wt% of isocyanate, 1-2 wt% of catalyst, 1-3 wt% of surfactant and 2-4 wt% of water at a high speed of 1500-3000 r/min for 5-20 min to obtain the polyurethane foam. Preferably, the polyurethane foam prepared later is more stable and uniform.

Further, wherein the catalyst is prepared by mixing dibutyltin dilaurate and triethanolamine in a weight ratio of 3: 1; the surfactant is Tween 80 or silicone oil.

Further, in the step 4), the forming pressure is 0.5-100Mpa, and the dwell time is 2-120 minutes; the preferable molding pressure is 2-20MPa, the dwell time is 4-15 minutes, and the preferable post-molding density is better.

Further, in the step 5), the drying temperature is 25-200 ℃, and the drying time is more than or equal to 2 hours.

Further, in the step 6), the carbonization temperature is less than or equal to 1200 ℃, and the carbonization time is more than or equal to 6 hours.

Further, in step 6), the vacuum pressure is 5-100Pa, preferably 10-50Pa, and preferably the post-vacuum degree is easy to reach; the inert atmosphere is preferably argon, so that the cost is low.

In order to achieve the purpose, the invention also provides a nano-pore heat insulation material, wherein the compressive strength of the nano-pore heat insulation material is 3.5MPa to 4.2MPa, the breaking strength is 1.2MPa to 1.5MPa, and the heat conductivity coefficient is 0.016W/mK to 0.025W/mK.

Further wherein the nanoporous thermal insulating material is prepared by the method described above.

By the technical scheme, the invention at least has the following advantages:

1. the heat insulating material has good strength and can be machined. Because the carbon skeleton is formed after the polyurethane foam and the resin are carbonized, the carbon skeleton has better strength and can be subjected to mechanical finish machining.

2. The material does not fall powder or slag. The nano powder and the polyurethane foam preparation raw material are stirred at a high speed, most of the powder is wrapped inside closed holes of the polyurethane foam, and part of the powder which is not wrapped is filled between the foams or is connected by resin.

3. The addition of the opacifier reduces the radiation heat transfer of the thermal insulation material in a high-temperature use environment. According to mie scattering theory, the particle size, when compared to the wavelength, will produce the greatest scattering of infrared light. For this purpose, ceramic powder particle opacifiers having a large absorption coefficient or scattering coefficient are placed on the path of the thermal radiation propagation, so that the apparent extinction coefficient of the material can be increased to attenuate the radiation.

4. The heat insulation performance is good, and the service temperature is high. The heat insulating material of the present invention has carbonaceous closed pores to coat the nanometer powder, and has maximum use temperature up to 1200 deg.c in vacuum or inert atmosphere, which is 1 time higher than that of common silica aerogel. Due to the existence of the closed holes, the convective heat transfer is further reduced, so that the heat insulation performance of the heat insulation material is excellent, and the heat conductivity coefficient can be as low as 0.016W/mK.

5. The flame-retardant and fire-proof grade is high. The heat-insulating material of the invention is prepared by high-temperature carbonization and decomposition of organic components, and the remained substances are inorganic components, so that the heat-insulating material can be used as a class A non-combustible material in the fields with high fire-proof grade requirements such as exterior wall heat preservation and the like.

Detailed Description

The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.

The following materials or reagents are commercially available unless otherwise specified.

Example 1

The embodiment provides a preparation method of a nanopore thermal insulation material, which comprises the following steps:

1) diluting 5 parts by weight of phenolic resin with water until the solid phase content is 40 wt%;

2) uniformly mixing and stirring the thermosetting resin diluent obtained in the step 1), 83 parts by weight of nano powder and 2 parts by weight of opacifier (the stirring speed is 1000 revolutions per minute, and the stirring time is 10 minutes);

3) uniformly mixing 10 parts by weight of polyurethane foam (namely, stirring 45 wt% of polyether polyol, 50 wt% of isocyanate, 1 wt% of catalyst, 2 wt% of surfactant and 2 wt% of water at a high speed of 1500-3000 r/min for 5-20 min to obtain the polyurethane foam) with the particles obtained in the step 2) under a high-speed stirring condition (the stirring speed is 3000 r/min, and the stirring time is 10 min);

4) pouring the sticky particles obtained in the step 3) into a mould for molding (the molding pressure is 4Mpa, and the pressure maintaining time is 5 minutes);

5) drying the block obtained in step 4) at 25 ℃ for 2 hours;

6) taking the material dried in the step 5) out of the mold, and carbonizing the material under a vacuum condition (vacuum pressure is 40Pa) at 1200 ℃ for 6 hours to obtain the nanopore heat insulation material.

Example 2

1) diluting 30 parts by weight of phenolic resin with absolute ethyl alcohol until the solid phase content is 10 wt%;

2) uniformly mixing and stirring the thermosetting resin diluent obtained in the step 1), 30 parts by weight of nano powder and 5 parts by weight of opacifier (the stirring speed is 800 revolutions per minute, and the stirring time is 10 minutes);

3) uniformly mixing 10 parts by weight of polyurethane foam (namely, stirring 45 wt% of polyether polyol, 50 wt% of isocyanate, 1 wt% of catalyst, 2 wt% of surfactant and 2 wt% of water at a high speed of 1500-3000 r/min for 5-20 min to obtain the polyurethane foam) with the particles obtained in the step 2) under a high-speed stirring condition (the stirring speed is 2500 r/min, and the stirring time is 15 min);

4) pouring the sticky particles obtained in the step 3) into a mould for molding (the molding pressure is 5Mpa, and the pressure maintaining time is 10 minutes);

5) drying the block obtained in step 4) at 200 ℃ for 12 hours;

6) taking the material dried in the step 5) out of the mold, and carbonizing at 800 ℃ for 12 hours in an argon atmosphere or argon atmosphere to obtain the nanopore heat insulation material.

Example 3

1) diluting 15 parts by weight of epoxy resin with absolute ethyl alcohol until the solid phase content is 20 wt%;

2) uniformly mixing and stirring the thermosetting resin diluent obtained in the step 1), 40 parts by weight of nano powder and 5 parts by weight of opacifier (the stirring speed is 1000 revolutions per minute, and the stirring time is 5 minutes);

3) uniformly mixing 40 parts by weight of polyurethane foam (namely, stirring 45 wt% of polyether polyol, 50 wt% of isocyanate, 1 wt% of catalyst, 2 wt% of surfactant and 2 wt% of water at a high speed of 1500-3000 r/min for 5-20 min to obtain the polyurethane foam) with the particles obtained in the step 2) under a high-speed stirring condition (the stirring speed is 3000 r/min, and the stirring time is 10 min);

4) pouring the sticky particles obtained in the step 3) into a mould for molding (the molding pressure is 10Mpa, and the pressure maintaining time is 5 minutes);

5) drying the block obtained in step 4) at 150 ℃ for 6 hours;

6) taking the material dried in the step 5) out of the mould, and carbonizing the material under the vacuum condition (the vacuum pressure is 30Pa) at the carbonization temperature of 800 ℃ for 18 hours.

Example 4

2) uniformly mixing and stirring the thermosetting resin diluent obtained in the step 1) with 75 parts by weight of nano powder and 10 parts by weight of opacifier (the stirring speed is 1000 revolutions per minute, and the stirring time is 10 minutes);

5) drying the block obtained in step 4) at 25 ℃ for 2 hours;

Example 5

2) uniformly mixing and stirring the thermosetting resin diluent obtained in the step 1) with 70 parts by weight of nano powder and 15 parts by weight of opacifier (the stirring speed is 1000 revolutions per minute, and the stirring time is 10 minutes);

5) drying the block obtained in step 4) at 25 ℃ for 2 hours;

The nanoporous thermal insulation materials prepared in examples 1-5 above and the thermal insulation materials of comparative examples 1-2 were tested as follows, and the test results are shown in Table 1, wherein comparative example 1 is different from example 5 in that comparative example 1 does not contain an opacifier, and the rest of the raw materials and steps are the same as example 5; comparative example 2 is a commercially available aerogel.

TABLE 1 compression Strength, flexural Strength, thermal conductivity and service temperature tests of examples 1-5 and comparative examples 1-2

As can be seen from the data in Table 1, the compressive strength of the nanoporous thermal insulation materials prepared in examples 1-5 is 3.2MPa-4.2MPa, the flexural strength is 1.1MPa-1.5MPa, the thermal conductivity at normal temperature is 0.016W/mK-0.025W/mK, the thermal conductivity at high temperature (600 ℃) is 0.025W/mK-0.040W/mK, the service temperature is 1200 ℃, which is far higher than the service temperature (increased by nearly 1 time) and the compressive strength of the commercially available aerogel of comparative example 2; comparing example 5 with comparative example 1, comparative example 1 has a thermal conductivity at 600 ℃ in the use environment which is significantly higher than that of the nanoporous thermal insulation material of example 5 in the same use environment due to the absence of the opacifier, while the thermal conductivity of the nanoporous thermal insulation material in the normal temperature use environment is the same, because the addition of the opacifier in example 5 reduces the radiation heat transfer of the thermal insulation material in the high temperature use environment, but the opacifier has no effect on the radiation heat transfer of the thermal insulation material at normal temperature.

In order to reduce the radiation heat transfer of the nano-pore heat insulation material at high temperature, ceramic powder particles with larger reflectivity can be placed on a heat radiation transmission passage to serve as an opacifier, so that the apparent extinction coefficient of the material is improved, and the heat radiation effect is attenuated. The thermal conductivity of the material at high temperature is significantly reduced.

According to the invention, the nano powder and the polyurethane foam are compounded, so that the powder is wrapped inside the closed hole of the polyurethane foam, part of the powder which is not wrapped is filled between the foams or is connected by resin, and the phenomena of powder falling and slag falling caused by the fact that the powder is directly molded into a block are avoided. Meanwhile, a carbon skeleton is formed after the organic matter is carbonized, so that the strength and the processability of the material are greatly improved.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A preparation method of a nanopore heat insulation material is characterized by comprising the following steps:

2) mixing and stirring uniformly the thermosetting resin diluent obtained in the step 1), 20-90 parts by weight of nano powder and 2-30 parts by weight of opacifier; the nano powder is selected from aerogel powder or white carbon black powder with a nano pore structure, and the size of the nano pore structure is less than 500 nanometers; the opacifier comprises at least one of titanium oxide, silicon carbide, zirconium oxide and graphite, and the particle size of the opacifier is 0.3-100 microns;

3) uniformly mixing 10-80 parts by weight of polyurethane foam and the particles obtained in the step 2) under a high-speed stirring condition; the high-speed stirring speed is 500-;

5) drying the block obtained in the step 4);

2. The method according to claim 1, wherein in step 1), the thermosetting resin is selected from the group consisting of phenol resin and epoxy resin.

3. The method as claimed in claim 1, wherein the mixing and stirring speed in step 2) is 500-2000 rpm for 5-60 min.

4. The method of claim 1, wherein in step 3), the polyurethane foam is prepared by:

5. A method of making according to claim 4, wherein the catalyst is prepared by mixing dibutyltin dilaurate and triethanolamine in a weight ratio of 3: 1; the surfactant is Tween 80 or silicone oil.

6. The method according to claim 1, wherein in the step 4), the molding pressure is 0.5 to 100Mpa, and the dwell time is 2 to 120 minutes; in the step 5), the drying temperature is 25-200 ℃, and the drying time is more than or equal to 2 hours.

7. The method according to claim 1, wherein in the step 6), the vacuum pressure is 5 to 100 Pa; the inert atmosphere is argon atmosphere; the carbonization temperature is less than or equal to 1200 ℃, and the carbonization time is more than or equal to 6 hours.

8. A nano-pore heat insulation material is characterized in that the compression strength of the nano-pore heat insulation material is 3.5MPa to 4.2MPa, the breaking strength is 1.2MPa to 1.5MPa, and the heat conductivity coefficient is 0.016W/mK to 0.025W/mK; the nanoporous thermal insulation material is prepared by the method of any one of claims 1 to 7.