Lightweight heat-proof and heat-insulation phenolic resin-based composite material and preparation method thereof

Abstract

The invention provides a light heat-proof and heat-insulation phenolic resin-based composite material and a preparation method thereof. The light heat-proof and heat-insulation phenolic resin-based composite material comprises a reinforcing material and a resin matrix, the resin matrix comprises phenolic resin, a modifier and a light filler; the mass of the modifier is 0.5%-5% of the mass of the phenolic resin; the mass of the light filler is 30-70% of the mass of the phenolic resin; and the modifier is dicyandiamide. The density of the composite material is 0.6-0.9 g / cm < 3 >, and the composite material meets use requirements, is excellent in mechanical property, is formed by adopting a non-autoclave, and is low in manufacturing cost and high in production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a lightweight heat-insulating phenolic resin-based composite material and a preparation method thereof. Background Art

[0002] The ablative aircraft thermal protection system usually consists of two structures, namely the ablative layer and the thermal insulation layer. The ablative layer working outside the aircraft maintains its appearance and has excellent anti-ablation ability. It usually has a higher density. The thermal insulation layer located inside the ablative layer has a lower density and is used to prevent the external high temperature from diffusing inward and affecting the normal operation of internal components.

[0003] For the thermal insulation layer, fiber-reinforced resin-based composite materials are mostly used. As the thermal insulation layer of the ablative aircraft thermal protection system, in addition to having good thermal insulation performance, it is also required to have low density and strong mechanical properties. However, under normal circumstances, reducing the density of the thermal insulation layer material will lead to a decrease in mechanical strength. The Chinese patent document with publication number CN 108517102 B discloses a lightweight thermal insulation composite material and a preparation method thereof. By introducing organic fibers to reduce the density of the thermal insulation material, the density of the short fiber reinforced phenolic resin-based thermal protection composite material is reduced to 0.9 g / cm 3 , which is suitable for molding, isostatic pressing, or layering, but the density of the thermal insulation layer material prepared by this method is still relatively high, and the mechanical strength of the short fiber reinforced composite material is not high.

[0004] In addition, currently, thermal protection materials for aircraft are usually formed by autoclaves, which limits the size of the parts and requires large capital investment in the forming process and high operating costs, which is not conducive to the low-cost requirements of aircraft. A Chinese patent document with publication number CN 11574808 A discloses a lightweight thermal insulation composite material and a preparation method thereof, wherein phenolic resin and short-cut blended fibers are uniformly mixed to prepare a lightweight blended fiber prepreg, but this method adopts compression molding, which is limited by the mold and is not conducive to the application of thermal insulation materials for special-shaped aircraft. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a lightweight heat-insulating phenolic resin-based composite material and a preparation method thereof, wherein the density of the composite material is 0.6-0.9 g / cm 3 , meets the use requirements, has excellent mechanical properties, is formed by non-autoclave, has low manufacturing cost and high production efficiency.

[0006] In order to solve the above problems, one aspect of the present invention provides a lightweight heat-insulating phenolic resin-based composite material, comprising: Reinforcing material and resin matrix; the resin matrix includes phenolic resin, modifier and lightweight filler; the mass of the modifier is 0.5% to 5% of the mass of the phenolic resin; the mass of the lightweight filler is 30% to 70% of the mass of the phenolic resin; the modifier is dicyandiamide.

[0007] Preferably, the lightweight filler is at least one of hollow glass microspheres, expanded microspheres, and phenolic resin microspheres.

[0008] Preferably, the reinforcing material is at least one of glass fiber felt, quartz fiber felt, polyimide fiber felt, aramid fiber felt, quartz fiber mesh cloth, a blended fabric of glass fiber and aramid fiber, a blended fabric of glass fiber and polyimide fiber, a blended fabric of quartz fiber and aramid fiber, and a blended fabric of quartz fiber and polyimide fiber.

[0009] Preferably, the phenolic resin is at least one of aminophenolic resin, bariumphenolic resin and magnesiumphenolic resin.

[0010] Preferably, the mass of the modifier is 1.5% to 3.5% of the mass of the phenolic resin.

[0011] Preferably, the mass of the lightweight filler is 33% to 67% of the mass of the phenolic resin.

[0012] Another aspect of the present invention provides a method for preparing the above-mentioned lightweight heat-insulating phenolic resin-based composite material, comprising the following steps: S1. melting the phenolic resin; S2. The molten phenolic resin is mixed with a modifier and a lightweight filler to obtain a mixture; S3. The mixture is formed into a film; S4. The film and the reinforcing material are hot-pressed to obtain a prepreg; S5. Lay the prepreg layers and cure them by vacuum bag pressing process to obtain the lightweight heat-insulating phenolic resin-based composite material.

[0013] Preferably, the mixture is made into a film, which specifically comprises the following steps: The mixture is coated into a film by using a coating production device of a hot melt prepreg machine, the coating temperature is 60-70°C, and the surface density of the film is controlled by adjusting the roller gap and the coating speed, and the coating speed is 3-6m / min.

[0014] Preferably, the adhesive film and the reinforcing material are hot pressed and laminated, specifically comprising the following steps: The hot-melt prepreg machine is used for hot pressing and laminating, the pressing roller temperature is 70-90°C, and the laminating speed is 3-6 m / min.

[0015] Preferably, when the vacuum bag pressing process is used for curing, the curing temperature is: heating to 85-95°C and keeping warm for 1-3 hours; then heating to 115-125°C and keeping warm for 1-3 hours; finally heating to 150-170°C and keeping warm for 3-6 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The lightweight heat-insulating phenolic resin-based composite material of the present invention controllably reduces the density of the phenolic resin-based composite material by introducing an appropriate amount of lightweight filler, and the density of the obtained heat-insulating phenolic resin-based composite material is 0.6-0.9 g / cm 3 , having a smaller density; due to the introduction of lightweight fillers, the mechanical strength of the material is reduced. The present invention adds dicyandiamide as a modifier to modify the phenolic resin. The dicyandiamide molecular structure has terminal amino groups, which can react with formaldehyde under alkaline conditions to undergo hydroxymethylation, thereby introducing the dicyandiamide molecules into the structure of the phenolic resin. At the same time, since the molecules are chain-shaped, they can play a toughening role, thereby improving the mechanical properties of the phenolic resin-based composite material.

[0017] The method for preparing a lightweight heat-insulating phenolic resin-based composite material of the present invention adopts a hot melt method to prepare a prepreg from a resin, a modifier, a lightweight filler and a reinforcing material. Compared with the impregnation method, the content of the phenolic resin in the prepreg can be more accurately controlled, and the method has the advantages of simple process and high production efficiency, and is suitable for winding, draping and other molding methods. The curing adopts a vacuum bag pressing process, and does not use an autoclave for molding, and only requires vacuuming, which can greatly reduce the manufacturing cost of the material and significantly improve the production efficiency. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] One aspect of an embodiment of the present invention provides a lightweight heat-insulating phenolic resin-based composite material, comprising: Reinforcing material and resin matrix; the resin matrix includes phenolic resin, modifier and lightweight filler; the mass of the modifier is 0.5% to 5% of the mass of the phenolic resin; the mass of the lightweight filler is 30% to 70% of the mass of the phenolic resin; the modifier is dicyandiamide.

[0020] The lightweight heat-insulating phenolic resin-based composite material of the present invention controllably reduces the density of the phenolic resin-based composite material by introducing an appropriate amount of lightweight filler, and the density of the obtained heat-insulating phenolic resin-based composite material is 0.6-0.9 g / cm 3 , having a smaller density; due to the introduction of lightweight fillers, the mechanical strength of the material is reduced. The present invention adds dicyandiamide as a modifier to modify the phenolic resin. The dicyandiamide molecular structure has terminal amino groups, which can react with formaldehyde under alkaline conditions to undergo hydroxymethylation, thereby introducing the dicyandiamide molecules into the structure of the phenolic resin. At the same time, since the molecules are chain-shaped, they can play a toughening role, thereby improving the mechanical properties of the phenolic resin-based composite material.

[0021] In some embodiments, the lightweight filler is at least one of hollow glass microspheres, expanded microspheres, and phenolic resin microspheres.

[0022] In some embodiments, the reinforcing material is at least one of glass fiber felt, quartz fiber felt, polyimide fiber felt, aramid fiber felt, quartz fiber mesh cloth, a blended fabric of glass fiber and aramid fiber, a blended fabric of glass fiber and polyimide fiber, a blended fabric of quartz fiber and aramid fiber, and a blended fabric of quartz fiber and polyimide fiber.

[0023] In some embodiments, the proportion of the reinforcing material to the composite material is 5%-30%. Preferably, the proportion of the reinforcing material to the composite material is 12%-30%.

[0024] In some embodiments, the phenolic resin is at least one of an aminophenolic resin, a bariumphenolic resin, and a magnesiumphenolic resin.

[0025] In some embodiments, the mass of the light filler is 33% to 67% of the mass of the phenolic resin. The mass content of the light filler can be adjusted within this range. By adjusting the content of the light filler, the content of the light filler can be adjusted to 0.6 to 0.9 g / cm 3 The density of the composite material can be controlled within a certain range.

[0026] In some embodiments, preferably, the mass of the modifier is 1.5% to 3.5% of the mass of the phenolic resin; within this mass content range, the lightweight heat-insulating phenolic resin-based composite material can have better mechanical properties while having a low density. More preferably, the mass of the modifier is 2.5% of the mass of the phenolic resin, and this mass content can make the lightweight heat-insulating phenolic resin-based composite material have low density and optimal mechanical properties.

[0027] Another aspect of the present invention provides a method for preparing the above-mentioned lightweight heat-insulating phenolic resin-based composite material, comprising the following steps: S1. melting the phenolic resin; S2. The molten phenolic resin is mixed with a modifier and a lightweight filler to obtain a mixture; S3. The mixture is formed into a film; S4. The film and the reinforcing material are hot-pressed to obtain a prepreg; S5. Lay the prepreg layers and cure them by vacuum bag pressing process to obtain the lightweight heat-insulating phenolic resin-based composite material.

[0028] The method for preparing the lightweight heat-insulating phenolic resin-based composite material of the embodiment of the present invention adopts a hot melt method to prepare a prepreg with resin, a modifier, a lightweight filler and a reinforcing material. Compared with the impregnation method, the content of phenolic resin in the prepreg can be more accurately controlled, and it has the advantages of simple process and high production efficiency, and is suitable for winding, draping and other molding methods; the curing adopts a vacuum bag pressing process, and does not use autoclave molding, and only requires vacuuming, which can greatly reduce the manufacturing cost of the material and significantly improve production efficiency.

[0029] In some embodiments, melting the phenolic resin specifically comprises the following steps: The hot-melt phenolic resin is heated at a temperature of 60-75° C. for 0.5-1 hour to melt the hot-melt phenolic resin.

[0030] In some embodiments, the mixing of the molten phenolic resin with the modifier and the lightweight filler specifically includes the following steps: using a high-speed mixer to mix the molten hot-melt phenolic resin with the modifier and the lightweight functional filler.

[0031] In some embodiments, the mixture is made into a film, specifically comprising the following steps: The mixture is coated into a film by using a coating production device of a hot melt prepreg machine, the coating temperature is 60-70°C, and the surface density of the film is controlled by adjusting the roller gap and the coating speed, and the coating speed is 3-6m / min.

[0032] Preferably, the film surface density is controlled to be 140-230 g / m 2 .

[0033] Preferably, the resin content in the film is 60%-75%.

[0034] In some embodiments, the adhesive film and the reinforcing material are hot-pressed and laminated, specifically comprising the following steps: A layer of adhesive film is placed at the bottom and a reinforcing material is placed in the middle. The composite production device of the hot melt prepreg machine is used for hot pressing and compounding. The temperature of the pressing roller is 70-90°C and the compounding speed is 3-6 m / min.

[0035] In some embodiments, when the vacuum bag pressing process is used for curing, the curing temperature is: heating to 85-95°C and keeping warm for 1-3 hours; then heating to 115-125°C and keeping warm for 1-3 hours; finally heating to 150-170°C and keeping warm for 3-6 hours.

[0036] Example 1 The lightweight heat-insulating phenolic resin-based composite material of this embodiment includes: Reinforcement material and resin matrix; the resin matrix includes phenolic resin, modifier and light filler; the reinforcement material is a quartz fiber and aromatic sulfone fiber mixed fabric; the phenolic resin is aminophenol resin; the modifier is dicyandiamide; the light filler is hollow glass microspheres. In the composite material, the mass ratio of the reinforcement material is 26%; the mass of the modifier is 2.5% of the mass of the phenolic resin; the mass of the light filler is 33% of the mass of the phenolic resin.

[0037] The method for preparing the lightweight heat-insulating phenolic resin-based composite material of this embodiment comprises the following steps: S1. Heat the hot-melt phenolic resin at 65° C. for 1 hour to melt the hot-melt phenolic resin.

[0038] S2. Use a high-speed stirrer to mix the molten phenolic resin, the modifier and the lightweight filler to obtain a mixture.

[0039] S3. The mixture was coated into a film with uniform thickness using a hot melt prepreg machine. The coating temperature was 65°C. The coating speed was 3 m / min and the film surface density was controlled to be 140 g / m by adjusting the roller gap and coating speed. 2 , so that the resin content in the film is 75%.

[0040] S4. The adhesive film and the reinforcing material are stacked and then hot-pressed to obtain a prepreg. A hot-melt prepreg machine composite production device is used. When the pressure roller is heated, a layer of adhesive film is placed on the top and bottom, and a quartz fiber and aromatic sulfone fiber mixed fabric is placed in the middle as a reinforcing material. The prepreg is obtained by hot-pressing and compounding. The pressure roller temperature is controlled at 70-85°C and the compounding speed is controlled at 3m / min to obtain a lightweight anti-insulation phenolic resin-based hot-melt prepreg, in which the proportion of the reinforcing material in the composite material is 26%.

[0041] S5. Prepare the above prepreg into a composite material preform by laying it at an angle of 15°.

[0042] S6. Place an isolation film, adhesive felt, and vacuum bag on the surface of the composite material preform in sequence, put it into a curing furnace, and then evacuate it to a vacuum degree of ≤25kPa, then heat it to 90℃ at a heating rate of ≤30℃ / h, and keep it warm for 2 hours; then heat it to 120℃ at a heating rate of ≤15℃ / h, and keep it warm for 2 hours; finally heat it to 160℃ at a heating rate of ≤15℃ / h, and keep it warm for 4 hours. Complete the curing to obtain a lightweight heat-insulating phenolic resin-based composite material.

[0043] Comparative Example 1 The preparation method of the hot-melt phenolic resin composite material of this comparative example is the same as that of Example 1 in other steps, raw materials and dosages, except that the autoclave is used for curing, and the curing system is as follows: heating to 90°C at a heating rate of ≤30°C / h, keeping warm for 2h; then heating to 105°C at a heating rate of ≤25°C / h, with a pressure of 1.2 MPa, keeping warm for 2h; finally heating to 160°C at a heating rate of ≤20°C / h, with a pressure of 1.2 MPa, keeping warm for 4h. The curing is completed.

[0044] Example 2 The lightweight heat-insulating phenolic resin-based composite material of this embodiment includes: Reinforcement material and resin matrix; the resin matrix includes phenolic resin, modifier and light filler; the reinforcement material is a glass fiber and aromatic sulfone fiber mixed fabric; the phenolic resin is aminophenol resin; the modifier is dicyandiamide; the light filler is hollow glass microspheres. In the composite material, the mass ratio of the reinforcement material is 26%; the mass of the modifier is 2.5% of the mass of the phenolic resin; the mass of the light filler is 50% of the mass of the phenolic resin.

[0045] The method for preparing the lightweight heat-insulating phenolic resin-based composite material of this embodiment comprises the following steps: S1. Heat the hot-melt phenolic resin at 70° C. for 1 hour to melt the hot-melt phenolic resin.

[0046] S2. Use a high-speed stirrer to mix the molten phenolic resin, the modifier and the lightweight filler to obtain a mixture.

[0047] S3. The mixture was coated into a film with uniform thickness using a hot melt prepreg machine. The coating temperature was 70°C. The coating speed was 3 m / min and the film surface density was controlled to be 230 g / m by adjusting the roller gap and coating speed. 2 , so that the resin content in the film is 67%.

[0048] S4. The adhesive film and the reinforcing material are stacked and then hot-pressed to obtain a prepreg. A hot-melt prepreg machine composite production device is used. When the pressure roller is heated, a layer of adhesive film is placed on the top and bottom, and a mixed fabric of glass fiber and aromatic sulfone fiber is placed in the middle as a reinforcing material. The prepreg is obtained by hot-pressing and compounding. The pressure roller temperature is controlled at 70-85°C and the compounding speed is controlled at 3m / min to obtain a lightweight anti-insulation phenolic resin-based hot-melt prepreg, in which the reinforcing material accounts for 30% of the composite material.

[0049] S5. Prepare the above prepreg into a composite material preform by laying it at an angle of 15°.

[0050] S6. Place an isolation film, adhesive felt, and vacuum bag on the surface of the composite material preform in sequence, put it into a curing furnace, and then evacuate it to a vacuum degree of ≤25kPa, then heat it to 90℃ at a heating rate of ≤30℃ / h, and keep it warm for 2 hours; then heat it to 120℃ at a heating rate of ≤15℃ / h, and keep it warm for 2 hours; finally heat it to 160℃ at a heating rate of ≤15℃ / h, and keep it warm for 4 hours. Complete the curing to obtain a lightweight heat-insulating phenolic resin-based composite material.

[0051] Comparative Example 2 The preparation method of the hot-melt phenolic resin composite material of this comparative example is the same as that of Example 2 in other steps, raw materials and dosages, except that the autoclave is used for curing, and the curing system is as follows: heating to 90°C at a heating rate of ≤30°C / h, keeping warm for 2h; then heating to 105°C at a heating rate of ≤25°C / h, the pressure is 1.0 MPa, and keeping warm for 2h; finally heating to 160°C at a heating rate of ≤20°C / h, the pressure is 1.0 MPa, and keeping warm for 4h. The curing is completed.

[0052] Example 3 The lightweight heat-insulating phenolic resin-based composite material of this embodiment includes: Reinforcement material and resin matrix; the resin matrix includes phenolic resin, modifier and light filler; the reinforcement material is a quartz fiber and polyimide fiber mixed fabric; the phenolic resin is aminophenol resin; the modifier is dicyandiamide; the light filler is hollow glass microspheres. In the composite material, the mass ratio of the reinforcement material is 26%; the mass of the modifier is 2.5% of the mass of the phenolic resin; the mass of the light filler is 67% of the mass of the phenolic resin.

[0053] The method for preparing the lightweight heat-insulating phenolic resin-based composite material of this embodiment comprises the following steps: S1. Heat the hot-melt phenolic resin at 70° C. for 1 hour to melt the hot-melt phenolic resin.

[0054] S2. Use a high-speed stirrer to mix the molten phenolic resin, the modifier and the lightweight filler to obtain a mixture.

[0055] S3. The mixture was coated into a film with uniform thickness using a hot melt prepreg machine. The coating temperature was 70°C. The coating speed was 3 m / min and the film surface density was controlled to be 230 g / m by adjusting the roller gap and coating speed. 2 , so that the resin content in the film is 67%.

[0056] S4. The adhesive film and the reinforcing material are stacked and then hot-pressed to obtain a prepreg. A hot-melt prepreg machine composite production device is used. When the pressure roller is heated, a layer of adhesive film is placed on the top and bottom, and a quartz fiber and polyimide fiber mixed fabric is placed in the middle as a reinforcing material. The prepreg is obtained by hot-pressing and compounding. The pressure roller temperature is controlled at 70-85°C, and the compounding speed is controlled at 3m / min to obtain a lightweight anti-insulation phenolic resin-based hot-melt prepreg, in which the proportion of the reinforcing material in the composite material is 12%.

[0057] S5. Prepare the above prepreg into a composite material preform by laying it flat.

[0058] S6. Place an isolation film, adhesive felt, and vacuum bag on the surface of the composite material preform in sequence, put it into a curing furnace, and then evacuate it to a vacuum degree of ≤25kPa, then heat it to 90℃ at a heating rate of ≤30℃ / h, and keep it warm for 2 hours; then heat it to 120℃ at a heating rate of ≤15℃ / h, and keep it warm for 2 hours; finally heat it to 160℃ at a heating rate of ≤15℃ / h, and keep it warm for 4 hours. Complete the curing to obtain a lightweight heat-insulating phenolic resin-based composite material.

[0059] Comparative Example 3 The preparation method of the hot-melt phenolic resin composite material of this comparative example is the same as that of Example 3 in other steps, raw materials and dosages, except that the autoclave is used for curing, and the curing system is as follows: heating to 90°C at a heating rate of ≤30°C / h, keeping warm for 2h; then heating to 105°C at a heating rate of ≤25°C / h, the pressure is 0.8 MPa, and keeping warm for 2h; finally heating to 160°C at a heating rate of ≤20°C / h, the pressure is 0.8 MPa, and keeping warm for 4h. The curing is completed.

[0060] Example 4 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Example 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the modifier dicyandiamide is 1.5% of the mass of the phenolic resin.

[0061] Example 5 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Example 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the modifier dicyandiamide is 3.5% of the mass of the phenolic resin.

[0062] Example 6 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Example 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the modifier dicyandiamide is 0.5% of the mass of the phenolic resin.

[0063] Example 7 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Example 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the modifier dicyandiamide is 5% of the mass of the phenolic resin.

[0064] Example 8 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Example 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the modifier dicyandiamide is 0.2% of the mass of the phenolic resin.

[0065] Example 9 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, except that in this embodiment, the mass of the modifier dicyandiamide is 8% of the mass of the phenolic resin.

[0066] Example 10 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the lightweight filler is 33% of the mass of the phenolic resin.

[0067] Embodiment 11 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the lightweight filler is 67% of the mass of the phenolic resin.

[0068] Example 12 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the lightweight filler is 30% of the mass of the phenolic resin.

[0069] Embodiment 13 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the lightweight filler is 70% of the mass of the phenolic resin.

[0070] Embodiment 14 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, with the difference being that in this embodiment, the mass of the lightweight filler is 25% of the mass of the phenolic resin.

[0071] Embodiment 15 The lightweight heat-insulating phenolic resin-based composite material of this embodiment is prepared in the same manner as in Embodiment 2 in terms of other raw materials and preparation method, except that in this embodiment, the mass of the lightweight filler is 75% of the mass of the phenolic resin.

[0072] Comparative Example 4 The rest of the raw materials and the preparation method of the lightweight heat-insulating phenolic resin-based composite material of this embodiment are the same as those of Example 2, except that the modifier dicyandiamide is not added.

[0073] The density, mechanical properties, and ablation properties of the composite materials obtained in the above-mentioned embodiments and comparative examples were measured. Density test was performed in accordance with GB / T 1463 standard requirements, tensile strength and elongation at break were tested in accordance with GB / T 1447 standard requirements, thermal conductivity test was performed in accordance with GB / T 10295 standard requirements, and oxyacetylene wire ablation rate test was performed in accordance with GJB 323A standard requirements.

[0074] The test results are shown in Tables 1 and 2 below. No dicyandiamide was added to Comparative Example 4. Although the composite material obtained had a lower density, its mechanical properties were significantly worse than those of the embodiments. Compared with Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, the preparation of raw materials and the remaining steps are the same, except that the comparative example adopts autoclave molding. In comparison, the products obtained in each embodiment have lower density than those in the corresponding comparative examples, and their strength properties are slightly worse than those in the comparative examples. However, the embodiments of the present invention adopt vacuum bag pressing technology, non-autoclave molding, low manufacturing cost and high production efficiency.

[0075] In each embodiment of the present invention, compared with Embodiment 2, 4-9, the difference is that the mass content of dicyandiamide added is different, wherein the content of dicyandiamide added in Embodiment 8 is too little, and the modification effect is not obvious. In Embodiment 9, too much dicyandiamide is added, resulting in poor dispersibility in the resin system, and the dicyandiamide that is not evenly dispersed becomes a defect in the material, resulting in significantly worse mechanical properties of the obtained product. Embodiments 2 and 4-7 are preferred embodiments, having density and mechanical properties that meet the requirements. Further, Embodiments 2, 4, and 5 are more preferred embodiments, and the product has better comprehensive performance.

[0076] Compared with Examples 2, 10-15, the difference is that the mass content of the added lightweight filler is different. Among them, the lightweight filler added in Example 14 is too little, and its density is greater than 0.9 g / cm 3, which does not meet the product performance requirements. Too much lightweight filler is added in Example 15, which leads to poor processability of film preparation and adversely affects the performance and quality uniformity of the composite material. Examples 2, 10-13 are preferred embodiments, which have density and mechanical properties that meet the requirements. Further, Examples 2, 10, and 11 are more preferred embodiments, and the product has better comprehensive performance.

[0077] Table 1

[0078] Table 2

[0079] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A lightweight heat-insulating phenolic resin-based composite material, characterized in that: include: Reinforcing material and resin matrix; the resin matrix includes phenolic resin, modifier and lightweight filler; the mass of the modifier is 0.5% to 5% of the mass of the phenolic resin; the mass of the lightweight filler is 30% to 70% of the mass of the phenolic resin; the modifier is dicyandiamide.

2. The lightweight heat-insulating phenolic resin-based composite material according to claim 1, characterized in that: The light filler is at least one of hollow glass microspheres, expanded microspheres, and phenolic resin microspheres.

3. The lightweight heat-insulating phenolic resin-based composite material according to claim 1, characterized in that: The reinforcing material is at least one of glass fiber felt, quartz fiber felt, polyimide fiber felt, aramid fiber felt, quartz fiber mesh cloth, glass fiber and aramid fiber blended fabric, glass fiber and polyimide fiber blended fabric, quartz fiber and aramid fiber blended fabric, and quartz fiber and polyimide fiber blended fabric.

4. The lightweight heat-insulating phenolic resin-based composite material according to claim 1, characterized in that: The phenolic resin is at least one of an aminophenolic resin, a bariumphenolic resin, and a magnesiumphenolic resin.

5. The lightweight heat-insulating phenolic resin-based composite material according to claim 1, characterized in that: The mass of the modifier is 1.5% to 3.5% of the mass of the phenolic resin.

6. The lightweight heat-insulating phenolic resin-based composite material according to claim 5, characterized in that: The mass of the lightweight filler is 33% to 67% of the mass of the phenolic resin.

7. A method for preparing a lightweight heat-insulating phenolic resin-based composite material as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1. melting the phenolic resin; S2. The molten phenolic resin is mixed with a modifier and a lightweight filler to obtain a mixture; S3. The mixture is formed into a film; S4. The film and the reinforcing material are hot-pressed to obtain a prepreg; S5. Lay the prepreg layers and cure them by vacuum bag pressing process to obtain the lightweight heat-insulating phenolic resin-based composite material.

8. The method for preparing the lightweight heat-insulating phenolic resin-based composite material according to claim 7, characterized in that: The mixture is made into a film, which specifically comprises the following steps: The mixture is coated into a film by using a coating production device of a hot melt prepreg machine, the coating temperature is 60-70°C, and the surface density of the film is controlled by adjusting the roller gap and the coating speed, and the coating speed is 3-6m / min.

9. The method for preparing the lightweight heat-insulating phenolic resin-based composite material according to claim 7, characterized in that: The adhesive film and the reinforcing material are hot pressed and laminated, specifically including the following steps: The hot-melt prepreg machine is used for hot pressing and laminating, the pressing roller temperature is 70-90°C, and the laminating speed is 3-6m / min.

10. The method for preparing the lightweight heat-insulating phenolic resin-based composite material according to claim 7, characterized in that: When the vacuum bag pressing process is used for curing, the curing temperature is: raise the temperature to 85~95℃ and keep it warm for 1~3h; then raise the temperature to 115~125℃ and keep it warm for 1~3h; finally raise the temperature to 150~170℃ and keep it warm for 3~6h.

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