Thermal insulation fireproof material based on fiber reinforcement and preparation method thereof

Abstract

The invention provides a thermal insulation fireproof material based on fiber reinforcement and a preparation method thereof. The thermal insulation fireproof material comprises a fiber reinforcement body and an isocyanate-benzoxazine aerogel matrix, the preparation raw materials of the isocyanate-benzoxazine aerogel matrix comprise isocyanate, benzoxazine modified polyol, a catalyst, a foaming agent and a solvent, under the condition of the modified isocyanate-benzoxazine aerogel matrix, the benzoxazine modified polyol provides a benzene ring and an oxazine structure for the gel matrix, and a urea group is introduced, so that the isocyanate-benzoxazine aerogel matrix is prepared. The thermal insulation fireproof material has the advantages that stability, thermal insulation and flame retardance under high-temperature conditions are provided for the fireproof material, hydroxyl of the fiber reinforcement and isocyanate of the isocyanate-benzoxazine aerogel matrix are cross-linked and cured to form a three-dimensional network structure, heat resistance of the thermal insulation fireproof material is enhanced synergistically, thermal expansion and deformation are reduced, and the thermal insulation fireproof material is high in thermal insulation performance. The material provided by the invention is widely applied to the fields requiring high performance, high strength and environment resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation materials, and in particular to a thermal insulation and fireproof material based on fiber reinforcement and a preparation method thereof. Background Art

[0002] Aerogel is a highly dispersed solid material with a nanoporous network structure composed of nano-scale colloidal particles aggregated together, and the pores are filled with gaseous dispersion medium. The unique three-dimensional network structure gives it excellent properties such as low density, high porosity, high specific surface area, and low thermal conductivity. Therefore, aerogel insulation material is a new type of high-efficiency insulation material with extremely low thermal conductivity, and has shown broad application prospects in the fields of aerospace, military equipment, civil buildings, and industrial pipeline insulation.

[0003] As a new type of high-performance material, polymer aerogel has shown unique advantages in many fields, especially in flame retardancy, showing more advantages than traditional aerogels (such as silicate aerogels and metal oxide aerogels). Polymer aerogels are not only lightweight and have excellent thermal insulation properties, but also can enhance flame retardancy through specific functional modifications, which makes them have broad application prospects in the construction, aerospace and electrical industries.

[0004] The thermal conductivity of polyisocyanate aerogel is very low, much lower than traditional insulation materials such as foam plastics, glass wool, etc. Its excellent thermal insulation properties make it an ideal material for energy saving and heat preservation in various industries. Polyisocyanate aerogel also has an extremely low density, which enables it to provide excellent thermal insulation without increasing weight; the low density of polyisocyanate aerogel makes it an ideal thermal insulation material for spacecraft, satellites and other aviation equipment, which helps to reduce structural weight and improve overall performance. The aerogel also has excellent electrical insulation properties, making it widely used in the electrical industry. Polyisocyanate aerogel can effectively prevent equipment from overheating caused by high temperature and protect electrical equipment from short circuits and damage, especially in high-voltage electronic equipment, transformers and other occasions that require high insulation performance.

[0005] Although polyisocyanate aerogel has low thermal conductivity and extremely low density, its performance at extremely high temperatures may not be as good as other materials (such as silicate aerogel), that is, its thermal stability is poor. In some special application areas, such as building materials in high-temperature environments or thermal insulation materials for spacecraft, the high-temperature stability of polyisocyanate aerogel needs to be further enhanced. Polyisocyanate aerogel still faces some challenges in practical applications and needs further improvement. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a fiber-reinforced thermal insulation and fireproof material and a preparation method thereof, so as to enhance the thermal insulation and flame retardant effects of polyisocyanate aerogel under high temperature conditions while maintaining its stability under high temperature conditions.

[0007] The technical solution of the present invention:

[0008] In a first aspect, the present invention provides a fiber-reinforced thermal insulation and fireproofing material, wherein the thermal insulation and fireproofing material comprises a fiber reinforcement and an isocyanate-benzoxazine aerogel matrix; the raw materials for preparing the isocyanate-benzoxazine aerogel matrix comprise isocyanate, benzoxazine-modified polyol, a catalyst, a blowing agent and a solvent.

[0009] In some embodiments, the fiber reinforcement is selected from one or a combination of glass fiber, ceramic fiber, basalt fiber, carbon fiber, and aromatic polyamide fiber; further, the fiber reinforcement is ceramic fiber.

[0010] In some embodiments, the isocyanate is selected from one or more combinations of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate.

[0011] In some embodiments, the structure of the benzoxazine-modified polyol is one of the structures shown in Formula 1 or Formula 2:

[0012]

[0013] In some embodiments, the method for preparing the benzoxazine-modified polyol comprises the following steps:

[0014] S1: dissolving benzophenone tetracarboxylic acid dianhydride in hydrochloric acid, adding water and heating to hydrolyze the anhydride group into a carboxyl group, adding ice water after the reaction is completed, and filtering the product to obtain benzophenone tetracarboxylic acid;

[0015] S2: adding benzophenone tetracarboxylic acid to a solvent, slowly adding lithium aluminum hydride and stirring to react, adding hydrochloric acid to neutralize after the reaction, layering and extracting the product, and obtaining tetrahydroxybenzophenone through extraction and drying;

[0016] S3: adding tetrahydroxybenzophenone to a solvent, and adding benzoxazine-6-carboxylic acid (CAS: 918789-44-3) to carry out an esterification reaction to obtain a benzoxazine-modified polyol as shown in Formula 1 or Formula 2.

[0017] In some embodiments, the molar ratio of tetrahydroxybenzophenone to benzoxazine-6-carboxylic acid is 1.2:0.8-1.

[0018] In some embodiments, the catalyst is selected from one of a tin-based catalyst, an organic amine catalyst, an organic metal compound or a quaternary ammonium salt catalyst, for example, it can be selected from one or more combinations of tin dioctoate, diethylamine, triethylamine, phenylbenzimidazole, an organic metal compound of bismuth or zinc, and tetramethylammonium chloride.

[0019] In some embodiments, the foaming agent is selected from one or more combinations of water, triethanolamine, carbon disulfide, sodium laurate, sodium stearate or sodium dodecylbenzene sulfonate.

[0020] In some embodiments, the solvent is selected from dichloromethane and / or n-hexane.

[0021] In another aspect, the present invention also provides a method for preparing the thermal insulation and fireproofing material, which specifically comprises the following steps:

[0022] S1: dissolving isocyanate and benzoxazine-modified polyol in a solvent; adding a catalyst to react to generate a polyisocyanate precursor; adding a foaming agent and controlling the temperature to react to obtain a gel structure;

[0023] S2: placing the fiber reinforcement in the above gel structure for reaction to obtain an aerogel precursor;

[0024] S3: placing the aerogel precursor in a water bath and heating it to ageing, placing it in a room temperature environment after aging and replacing it with ethanol, and placing it in an electric heated blast drying oven after replacement to dry it until the quality does not change, thereby obtaining a thermal insulation and fireproof material.

[0025] In some embodiments, the molar ratio of the isocyanate to the benzoxazine-modified polyol is 4.2-5:1.

[0026] In some embodiments, the mass ratio of the fiber reinforcement to the gel structure is 3-6:10.

[0027] Beneficial effects:

[0028] The fiber-reinforced thermal insulation and fireproofing material provided by the present invention is based on a modified isocyanate-benzoxazine aerogel matrix. The benzoxazine-modified polyol provides a benzene ring and an oxazine structure for the gel matrix, thereby providing the fireproofing material with stability, thermal insulation and flame retardancy under high temperature conditions. The hydroxyl groups of the fiber reinforcement are cross-linked and cured with the isocyanate groups of the isocyanate-benzoxazine aerogel matrix to form a three-dimensional network structure, which synergistically enhances the heat resistance of the thermal insulation and fireproofing material and reduces thermal expansion and deformation, so that the material provided by the present invention is widely used in fields requiring high performance, high strength and environmental resistance. DETAILED DESCRIPTION

[0029] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0030] Unless otherwise specified, the chemical reagents used in the present invention are all commercially available analytically pure. The ceramic fiber used in the examples was purchased from Zhejiang Aoka Refractory Materials Co., Ltd., with the product number AK-0045. The carbon fiber used in the examples was purchased from Shanghai Lishuo Composite Materials Technology Co., Ltd., model 082. The glass fiber used in the examples was purchased from Taian Haosong Fiber Co., Ltd., with a specification of 3-4.5 mm.

[0031] Preparation Example of Benzoxazine Modified Polyol

[0032] S1: Dissolve 5 mol of benzophenone tetracarboxylic dianhydride in 50 ml of hydrochloric acid, add 30 ml of water and heat to boiling, continue the reaction for 4 hours, cool to room temperature after the reaction, add ice water to neutralize the acidity, and filter the product to obtain benzophenone tetracarboxylic acid;

[0033] S2: Add the benzophenone tetracarboxylic acid prepared in S1 to 40 ml of anhydrous tetrahydrofuran, slowly add lithium aluminum hydride and stir for 4 hours to react, add hydrochloric acid to neutralize to pH 7 after the reaction, separate the layers and extract the product, extract and dry to obtain tetrahydroxybenzophenone;

[0034] S3: 1 mol of tetrahydroxybenzophenone obtained in S2 is added to 40 ml of anhydrous tetrahydrofuran, 1 mol of benzoxazine-6-carboxylic acid and 0.03 mol of concentrated sulfuric acid are added, and the mixture is heated to 90° C. for esterification reaction to obtain a product. The product is separated by high performance liquid chromatography to obtain a benzoxazine-modified polyol represented by formula 1 or formula 2.

[0035] Example 1

[0036] S1: 4.2 mol of toluene diisocyanate and 1 mol of benzoxazine-modified polyol shown in Formula 1 are dissolved in 60 ml of dichloromethane and stirred evenly; 0.15 mol of tin dioctoate is added, and the mixture is reacted at 50° C. for 3 h to generate a polyisocyanate precursor; 3 mol of water is added, and the temperature is controlled for cross-linking to obtain a gel structure;

[0037] S2: placing 30 g of the ceramic fiber body into 100 g of the above gel structure, and keeping the temperature at 35° C. for 2 h to react to obtain an aerogel precursor;

[0038] S3: The aerogel precursor is placed in a water bath and heated to 50°C for aging for 12 hours. After aging, it is placed in a room temperature environment and replaced with ethanol three times. After replacement, it is placed in an electric blast drying oven at 60°C for drying until the quality does not change, thereby obtaining a thermal insulation and fireproof material.

[0039] Example 2

[0040] The method is basically the same as Example 1, except that diphenylmethane diisocyanate is used to replace toluene diisocyanate, and carbon fiber is used to replace ceramic fiber.

[0041] Example 3

[0042] The method is basically the same as Example 1, except that isophorone diisocyanate is used to replace toluene diisocyanate, and glass fiber is used to replace ceramic fiber.

[0043] Example 4

[0044] The method is basically the same as Example 1, except that the benzoxazine-modified polyol shown in Formula 2 is used to replace the benzoxazine-modified polyol shown in Formula 1.

[0045] Example 5

[0046] The process is basically the same as Example 1, except that the added molar amounts of toluene diisocyanate and the benzoxazine modified polyol shown in Formula 1 are 4.7 mol and 1 mol, respectively.

[0047] Example 6

[0048] The process is basically the same as Example 1, except that the added molar amounts of toluene diisocyanate and the benzoxazine modified polyol shown in Formula 1 are 5 mol and 1 mol, respectively.

[0049] Comparative Example 1

[0050] The process is basically the same as Example 1, except that pentaerythritol is used to replace the benzoxazine-modified polyol shown in Formula 1.

[0051] Comparative Example 2

[0052] The process is basically the same as Example 1, except that tetrahydroxybenzophenone is used to replace the benzoxazine-modified polyol shown in Formula 1.

[0053] Comparative Example 3

[0054] The process is basically the same as Example 1, except that step S2 is omitted.

[0055] Comparative Example 4

[0056] 1 mol of pentaerythritol was added to 40 ml of anhydrous tetrahydrofuran, 1 mol of benzoxazine-6-carboxylic acid and 0.03 mol of concentrated sulfuric acid were added, and the mixture was heated to 90° C. for esterification reaction to obtain a product. The product was separated by high performance liquid chromatography to obtain a benzoxazine-modified polyol structure shown in formula 3.

[0057]

[0058] The remaining steps are basically the same as those in Example 1, except that the benzoxazine-modified polyol shown in Formula 3 is used to replace the benzoxazine-modified polyol shown in Formula 1.

[0059] Comparative Example 5

[0060] 1 mol of tetrahydroxybenzophenone was added to 40 ml of anhydrous tetrahydrofuran, 4.2 mol of benzoxazine-6-carboxylic acid and 0.1 mol of concentrated sulfuric acid were added, and the mixture was heated to 90° C. for esterification reaction to obtain a product. The product was separated by high performance liquid chromatography to obtain a benzoxazine-modified polyol as shown in formula 4.

[0061]

[0062] The remaining steps are basically the same as those in Example 1, except that the benzoxazine-modified polyol shown in Formula 4 is used to replace the benzoxazine-modified polyol shown in Formula 1.

[0063] Performance Testing

[0064] 1. After the thermal insulation and fireproof materials prepared in the examples and comparative examples were left to stand at 800°C for 15 days, the powder loss rate was measured with reference to the standard GB34336-2017.

[0065] 2. The thermal insulation and fireproof materials prepared in the examples and comparative examples were heated to 1200°C for 3 hours, kept at 1200°C for 30 minutes, and then cooled to 20°C by cold air. This was considered one cycle. A total of 20 cycles were performed to observe whether there were cracks on the surface of the thermal insulation and fireproof materials.

[0066] 3. The thermal insulation and fireproofing materials prepared in the examples and comparative examples were placed at 1000°C for thermal conductivity testing, and the test was conducted 5 times in total to take the average thermal conductivity.

[0067] 4. The thermal insulation and fireproofing materials prepared in the examples and comparative examples were subjected to density tests for a total of 5 times, and the average density was taken.

[0068] 5. The flame retardant properties of the thermal insulation and fireproofing materials prepared in the examples and comparative examples were measured with reference to the standard GB / T 8333-2008.

[0069] The test results are shown in the following table.

[0070] Table 1 Test data

[0071]

[0072]

[0073] It can be seen from the table data that the fiber-reinforced thermal insulation and fireproofing material provided by the present invention still has a low thermal conductivity, excellent flame retardant properties and low density under high temperature conditions, and there is no problem of particle shedding, thereby ensuring the mechanical properties under high temperature conditions.

[0074] In detail, it can be seen from the comparison between Comparative Examples 1, 2 and 4 and the Example that by using benzoxazine to modify the polyol, the gel structure is provided with a symmetrical benzene ring and an oxazine six-membered ring structure, which can greatly enhance the mechanical properties, heat resistance and chemical resistance of the aerogel; and the secondary amine group on the benzoxazine will also bond with the isocyanate group to introduce a urea group to form a more cross-linked structure, thereby improving the structural stability and mechanical strength of the aerogel and enhancing the flame retardant properties of the aerogel. Compared with Comparative Example 5, the fiber-reinforced thermal insulation and fireproof material provided in the Example does not make the gel too brittle, achieving an ideal effect.

[0075] The hydroxyl groups of the fiber reinforcement are cross-linked and cured with the isocyanate groups of the isocyanate-benzoxazine aerogel matrix to form a three-dimensional network structure, which synergistically enhances the heat resistance of the thermal insulation and fireproofing material and reduces thermal expansion and deformation.

[0076] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A fiber-reinforced thermal insulation and fireproof material, characterized in that: The thermal insulation and fireproof material comprises a fiber reinforcement and an isocyanate-benzoxazine aerogel matrix; the raw materials for preparing the isocyanate-benzoxazine aerogel matrix comprise isocyanate, benzoxazine-modified polyol, a catalyst, a foaming agent and a solvent.

2. The fiber-reinforced thermal insulation and fireproof material according to claim 1, characterized in that: The fiber reinforcement is selected from one or a combination of glass fiber, ceramic fiber, basalt fiber, carbon fiber, and aromatic polyamide fiber.

3. The fiber-reinforced thermal insulation and fireproof material according to claim 1, characterized in that: The isocyanate is selected from one or more combinations of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate.

4. The fiber-reinforced thermal insulation and fireproof material according to claim 1, characterized in that: The structure of the benzoxazine-modified polyol is one of the structures shown in Formula 1 or Formula 2:

5. The fiber-reinforced thermal insulation and fireproof material according to claim 1 or 4, characterized in that: The preparation method of the benzoxazine-modified polyol comprises the following steps: S1: dissolving benzophenone tetracarboxylic acid dianhydride in hydrochloric acid, adding water and heating to hydrolyze the anhydride group into a carboxyl group, adding ice water after the reaction is completed, and filtering the product to obtain benzophenone tetracarboxylic acid; S2: adding benzophenone tetracarboxylic acid to a solvent, slowly adding lithium aluminum hydride and stirring to react, adding hydrochloric acid to neutralize after the reaction, layering and extracting the product, and obtaining tetrahydroxybenzophenone through extraction and drying; S3: adding tetrahydroxybenzophenone to a solvent, and adding benzoxazine-6-carboxylic acid to carry out an esterification reaction to obtain a benzoxazine-modified polyol as shown in Formula 1 or Formula 2.

6. The fiber-reinforced thermal insulation and fireproof material according to claim 5, characterized in that: The molar ratio of the tetrahydroxybenzophenone to benzoxazine-6-carboxylic acid is 1.2:0.8-1.

7. The fiber-reinforced thermal insulation and fireproof material according to claim 1, characterized in that: The foaming agent is selected from one or more combinations of water, triethanolamine, carbon disulfide, sodium laurate, sodium stearate or sodium dodecylbenzene sulfonate.

8. The method for preparing the fiber-reinforced thermal insulation and fireproofing material according to any one of claims 1 to 7, characterized in that: The specific steps include: S1: dissolving isocyanate and benzoxazine-modified polyol in a solvent; adding a catalyst to react to generate a polyisocyanate precursor; adding a foaming agent and controlling the temperature to react to obtain a gel structure; S2: placing the fiber reinforcement in the above gel structure for reaction to obtain an aerogel precursor; S3: placing the aerogel precursor in a water bath and heating it to ageing, placing it in a room temperature environment after aging and replacing it with ethanol, and placing it in an electric heated blast drying oven after replacement to dry it until the quality does not change, thereby obtaining a thermal insulation and fireproof material.

9. The method for preparing the fiber-reinforced thermal insulation and fireproofing material according to claim 8, characterized in that: The molar ratio of the isocyanate to the benzoxazine modified polyol is 4.2-5:

1.

10. The method for preparing the fiber-reinforced thermal insulation and fireproofing material according to claim 8, characterized in that: The mass ratio of the fiber reinforcement to the gel structure is 3-6:10.

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