Low-temperature-resistant heat-insulating prepreg and preparation method thereof

Abstract

The invention belongs to the technical field of composite materials, and particularly relates to a low-temperature-resistant heat-insulating prepreg and a preparation method thereof.The prepreg is composed of a resin matrix and a fiber fabric, firstly, inorganic heat-insulating filler and thermal expansion microspheres which are light in weight, high in strength and good in heat-insulating effect are subjected to surface treatment and then introduced into resin, and the resin matrix and the fiber fabric are subjected to surface treatment; then the resin matrix is subjected to the processes of film coating, impregnation with fiber fabric and the like, and the low-temperature-resistant and heat-insulating prepreg is obtained. The prepreg can be co-cured and molded with a low-temperature composite material storage tank, has the advantages of low temperature resistance, low heat conductivity, good interface performance with a composite material and the like, does not need to process a heat insulation layer of the storage tank, has the characteristics of high molding processing efficiency, low cost and the like, and can further promote the development of the aerospace industry.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, in particular to a low-temperature resistant heat-insulating prepreg and a preparation method thereof. Background Art

[0002] Large launch vehicles use cryogenic liquid propellants such as liquid oxygen (≤-183℃), liquid hydrogen (≤-253℃), and liquid methane (≤-161.5℃), which have low temperatures and are volatile. Therefore, it is usually necessary to design an insulation layer on the outside of the cryogenic liquid propellant tank to maintain the low temperature environment inside the tank and reduce the volatilization of the cryogenic propellant. At present, the insulation layer is mostly completed after the tank is manufactured through subsequent processes such as pasting, spraying, and surface finishing. Since the tank structure and the insulation layer are not integrally formed, the physical and chemical properties of the tank material and the insulation layer material are quite different. Under high temperature gradients, it is easy to cause the insulation layer and the tank to debond at the interface, affecting the insulation effect. In addition, the later processing technology of the insulation layer is complicated, which increases the manufacturing cost of the launch vehicle and reduces the manufacturing efficiency.

[0003] At present, the tanks of launch vehicles are mainly made of metal materials, which have high thermal conductivity and high molding temperature, making it difficult to achieve integrated molding of the tank and the insulation layer. With the development of the aerospace industry, the use of carbon fiber reinforced resin-based composite materials to replace metal materials to manufacture large launch vehicle cryogenic propellant tanks has become the focus of research and application in the aerospace field at home and abroad. As an organic composite material, the fiber reinforced resin-based composite tank has good designability and processability, low curing molding temperature (generally below 200°C), and interface matching with commonly used insulation layer materials, and has the potential for integrated molding with the insulation layer.

[0004] At present, the research and application of low-temperature composite tanks for launch vehicles are progressing smoothly at home and abroad, and some models of launch vehicles have adopted composite materials. However, there is currently no thermal insulation prepreg that can be integrated with composite tanks. Such tanks still use insulation solutions similar to traditional metal tanks, and fail to give full play to the advantages of composite tanks. Therefore, it is of great significance to develop low-temperature resistant and thermal insulation prepregs for integrated molding of composite tanks and insulation layers. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a low-temperature resistant thermal insulation prepreg and a preparation method thereof.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A low-temperature resistant heat-insulating prepreg is composed of a resin matrix and a fiber fabric, wherein the weight of the resin matrix accounts for 20-45% and the weight of the fiber fabric accounts for 55-80%.

[0008] As a preferred embodiment of the low-temperature resistant thermal insulation prepreg described in the present invention, the resin matrix is ​​composed of epoxy resin, thermal expansion microspheres, inorganic thermal insulation filler, toughening agent, coupling agent and curing agent.

[0009] As a preferred embodiment of the low-temperature resistant thermal insulation prepreg described in the present invention, the weight ratio of epoxy resin to the resin matrix is ​​50-90%; the epoxy resin is composed of one or more of bisphenol A epoxy resin, multifunctional glycidylamine epoxy resin, phenolic epoxy resin, and aliphatic epoxy resin.

[0010] As a preferred embodiment of the low-temperature resistant thermal insulation prepreg described in the present invention, the weight ratio of the heat-expandable microspheres to the resin matrix is ​​0.5-20%; the heat-expandable microspheres are thermoplastic polymer microspheres whose volume increases significantly when heated, with a diameter of 10-100 μm, an expansion rate of 2-50 times, and a thermal expansion temperature of 80-120° C. The heat-expandable microspheres are composed of one or more of expandable polystyrene microspheres, phenolic resin microspheres, polyurethane microspheres, and acrylate microspheres.

[0011] As a preferred embodiment of the low-temperature resistant thermal insulation prepreg described in the present invention, the weight ratio of the inorganic thermal insulation filler to the resin matrix is ​​0.5-20%; the inorganic thermal insulation filler is an inorganic hollow material with good thermal insulation effect, light weight and high compressive strength, and the diameter of the hollow material is 1-300 μm and the density is 0.15-0.60 g / cm 3 ; The inorganic hollow material is composed of one or more of hollow glass microspheres, hollow silicon carbide microspheres, hollow alumina microspheres, hollow carbon microspheres, and hollow silica microspheres.

[0012] As a preferred embodiment of the low-temperature resistant thermal insulation prepreg described in the present invention, the toughening agent accounts for 3-15% of the weight of the resin matrix, and the toughening agent is composed of one or more of polyether sulfone, polyether ether ketone, nano rubber particles, nylon, polyurethane, and polyetherimide.

[0013] As a preferred embodiment of the low temperature resistant thermal insulation prepreg described in the present invention, the coupling agent is used in an amount of 0.5-10% of the weight of the inorganic thermal insulation filler or the thermal expansion microspheres; the coupling agent is composed of one or more of the organic silane coupling agents KH550, KH560, and KH570.

[0014] As a preferred embodiment of the low-temperature resistant thermal insulation prepreg described in the present invention, the amount of curing agent is 5-15% of the weight of the epoxy resin, and the curing agent is composed of one or more of diaminodiphenyl sulfone, dicyandiamide, polyetheramine, triethylenetetramine, urea accelerator, diaminoimidazole triazine complex, and boron trifluoride monoethylamine.

[0015] As a preferred embodiment of the low-temperature resistant heat-insulating prepreg described in the present invention, the fiber fabric is one of basalt fiber, aramid fiber, alumina fiber and glass fiber.

[0016] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution:

[0017] A method for preparing a low-temperature resistant thermal insulation prepreg comprises the following steps: firstly, a coupling agent is used to perform surface treatment on heat-expandable microspheres and inorganic thermal insulation fillers to improve the interface bonding effect between the heat-expandable microspheres, inorganic thermal insulation fillers and resin; then, the surface-treated heat-expandable microspheres and inorganic thermal insulation fillers are blended with epoxy resin, a toughening agent and a curing agent to obtain a resin matrix; and finally, the resin matrix is ​​subjected to a coating and fiber fabric impregnation process to obtain a low-temperature resistant thermal insulation prepreg.

[0018] The beneficial effects of the present invention are as follows:

[0019] The present invention provides a low temperature resistant heat insulating prepreg and a preparation method thereof. The prepreg is composed of a resin matrix and a fiber fabric. First, a light, high-strength, and heat-insulating inorganic heat insulating filler and a heat expansion microsphere are surface treated, and then introduced into a resin to obtain a resin matrix with a good heat insulating effect. Then, the resin matrix is ​​coated, impregnated with a fiber fabric, and other processes to obtain a low temperature resistant and heat insulating prepreg. The prepreg can be co-cured with a low temperature composite material tank, has the advantages of low temperature resistance, low thermal conductivity, and good interface performance with composite materials, and does not require processing of the tank insulation layer, has the characteristics of high molding processing efficiency and low cost, and can further promote the development of the aerospace industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the structure of the composite material with the heat insulation layer before curing of the present invention.

[0022] Figure 2It is a schematic diagram of the structure of the composite material with a heat insulation layer after curing of the present invention.

[0023] Figure 3 Comparison results of thermal conductivity of different materials.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. 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.

[0026] The main purpose of the present invention is to provide a low-temperature resistant thermal insulation prepreg and a preparation method thereof, wherein the prepreg can be integrally formed with a composite material tank, has good interface properties with the composite material for the low-temperature tank, and can automatically form an insulation layer on the surface of the composite material tank after forming.

[0027] According to one aspect of the present invention, the present invention provides the following technical solution:

[0028] A low-temperature resistant heat-insulating prepreg is composed of a resin matrix and a fiber fabric, wherein the weight of the resin matrix accounts for 20-45% and the weight of the fiber fabric accounts for 55-80%.

[0029] Preferably, the resin matrix is ​​composed of epoxy resin, heat-expandable microspheres, inorganic thermal insulation filler, toughening agent, coupling agent, and curing agent. The resin matrix of the present invention has excellent low temperature resistance and thermal insulation properties.

[0030] Preferably, the weight ratio of the epoxy resin to the resin matrix is ​​50-90%; the epoxy resin is composed of one or more of bisphenol A epoxy resin, multifunctional glycidylamine epoxy resin, phenolic epoxy resin, and aliphatic epoxy resin.

[0031] Preferably, the weight ratio of the heat-expandable microspheres to the resin matrix is ​​0.5-20%; the heat-expandable microspheres are thermoplastic polymer microspheres whose volume increases significantly when heated, with a diameter of 10-100 μm, an expansion rate of 2-50 times, and a thermal expansion temperature of 80-120° C. The heat-expandable microspheres are composed of one or more of expandable polystyrene microspheres, phenolic resin microspheres, polyurethane microspheres, and acrylic ester microspheres.

[0032] Preferably, the weight ratio of the inorganic thermal insulation filler to the resin matrix is ​​0.5-20%; the inorganic thermal insulation filler is an inorganic hollow material with good thermal insulation effect, light weight and high compressive strength, and the diameter of the hollow material is 1-300 μm and the density is 0.15-0.60 g / cm 3 ; The inorganic hollow material is composed of one or more of hollow glass microspheres, hollow silicon carbide microspheres, hollow alumina microspheres, hollow carbon microspheres, and hollow silica microspheres.

[0033] Preferably, the toughening agent accounts for 3-15% of the weight of the resin matrix, and the toughening agent is composed of one or more of polyethersulfone, polyetheretherketone, nano rubber particles, nylon, polyurethane, and polyetherimide.

[0034] Preferably, the amount of the coupling agent is 0.5-10% of the weight of the inorganic thermal insulation filler or the thermal expansion microsphere; the coupling agent is composed of one or more of the organic silane coupling agents KH550, KH560, and KH570.

[0035] Preferably, the amount of curing agent is 5-15% of the weight of the epoxy resin, and the curing agent is composed of one or more of diaminodiphenyl sulfone, dicyandiamide, polyetheramine, triethylenetetramine, urea accelerator, diaminoimidazole triazine complex, and boron trifluoride monoethylamine.

[0036] Preferably, the fiber is one of basalt fiber, aramid fiber, alumina fiber and glass fiber. The fiber used in the present invention has the advantages of excellent low temperature resistance, small thermal expansion coefficient, low thermal conductivity and the like.

[0037] According to another aspect of the present invention, the present invention provides the following technical solution:

[0038] A method for preparing a low-temperature resistant thermal insulation prepreg comprises the following steps: firstly, a coupling agent is used to perform surface treatment on heat-expandable microspheres and inorganic thermal insulation fillers to improve the interface bonding effect between the heat-expandable microspheres, inorganic thermal insulation fillers and resin; then, the surface-treated heat-expandable microspheres and inorganic thermal insulation fillers are blended with epoxy resin, a toughening agent and a curing agent to obtain a resin matrix; and finally, the resin matrix is ​​subjected to a coating and fiber fabric impregnation process to obtain a low-temperature resistant thermal insulation prepreg.

[0039] Preferably, the preparation method specifically comprises the following steps:

[0040] S1. Surface coupling agent treatment of heat-expandable microspheres: Stir the heat-expandable microspheres in a 0.5-1.5 mol / L hydrochloric acid, nitric acid or sulfuric acid solution for 30 min, wash the treated heat-expandable microspheres in acetone, dry them in a 40°C oven for 30-120 min, soak the dried heat-expandable microspheres in a pre-configured silane coupling agent anhydrous methanol or acetone solution, ultrasonically treat them for 1-3 h, and then dry them at 40°C for 1-4 h to obtain surface-treated heat-expandable microspheres;

[0041] S2. Treatment of the surface of the inorganic thermal insulation filler with a coupling agent: ultrasonically treat the inorganic thermal insulation filler in a 0.5-1.5 mol / L hydrochloric acid, nitric acid or sulfuric acid solution for 1 hour, wash the ultrasonically treated inorganic thermal insulation filler in distilled water, dry it in an oven at 80°C for 30-120 minutes, soak the dried hollow glass microspheres in a pre-configured silane coupling agent anhydrous ethanol, methanol or acetone solution, ultrasonically treat it for 1-3 hours, and then dry it at 80°C for 1-4 hours to obtain the surface-treated inorganic thermal insulation filler;

[0042] S3, preparation of resin matrix: first, epoxy resin and toughening agent are stirred and blended at 120-150°C to obtain a uniform mixed system, then cooled to 80-100°C, inorganic thermal insulation filler after surface treatment is added, and stirred for 30-120min; then cooled to 60-80°C, curing agent is added; the temperature is further cooled to 40-50°C, thermal expansion microspheres after surface treatment are added, and mixed evenly by a three-roll mill to obtain a resin matrix with a viscosity of 30-150Pa·S at room temperature, a viscosity of 5-20Pa·S at 50°C, a gel time of 50-100min, and a viscosity of 0.5-5Pa·S at 120-130°C, and a gel time of 30-50min; the specific gel time can be further adjusted according to the curing molding process of the composite tank, and the gel time of the resin matrix is ​​slightly lower than the gel time of the prepreg for composite tank molding;

[0043] S4, preparation of adhesive film: adjusting the temperature to 50-70°C, making the viscosity of the resin matrix 2-20 Pa·S, using coating process, adjusting the coating speed to 0.5-5 m / min, the gap between the rubber rollers to 0.1-1 mm, and controlling the surface density of the adhesive film;

[0044] S5. Preparation of prepreg: Impregnate the adhesive film on the fiber fabric, control the impregnation temperature to 50-60°C, make the resin viscosity to 5-20 Pa·S, adjust the impregnation speed to 2-3 m / min, and the gap between the pressure rollers to 0.05-0.5 mm, to obtain a low-temperature resistant and heat-insulating prepreg with a resin content of 20-55%.

[0045] According to another aspect of the present invention, the present invention provides the following technical solution:

[0046] A method for preparing a composite material component with an insulation layer by integral molding: after the composite material component is formed by laying, laying or winding, one or more layers of the above-mentioned low-temperature resistant insulation prepreg are laid on the surface of the formed composite material component by an automatic laying machine or manual laying, and then a good interface layer is formed by co-curing the low-temperature resistant insulation prepreg and the composite material according to a curing process. During the curing process, the thermal expansion microspheres expand to fill the gaps between the inorganic insulation fillers, thereby improving the insulation performance of the composite material, and obtaining a composite material component with an insulation layer. The composite material component is a composite material tank.

[0047] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0048] Example 1

[0049] A method for preparing a low-temperature resistant thermal insulation prepreg comprises the following steps:

[0050] S1. Take 100 g of hollow glass microspheres with a particle size of 5 to 10 μm and 500 g of hollow alumina microspheres with a particle size of 5 to 10 μm, add 1 mol / L hydrochloric acid solution (5 L) and ultrasonically treat for 1 h, wash the hollow microspheres after ultrasonic treatment in distilled water, and then dry them in an oven at 80°C for 50 min, soak the dried hollow microspheres in 10 g / L KH550 coupling agent methanol solution (2 L), ultrasonically treat for 1 h, the ultrasonic power is 2 kW, and then dry them at 70°C for 2 h;

[0051] S2, take 400g of expandable polystyrene and 400g of heat-expandable phenolic resin microspheres, stir and treat them in 0.5mol / L hydrochloric acid solution (5L) for 30min, wash the treated heat-expandable microspheres with acetone (5L) for several times, dry them in a 40℃ oven for 30min, soak the dried heat-expandable microspheres in 10g / L KH550 coupling agent methanol solution (2L), ultrasonically treat for 1h, and then dry them at 40℃ for 1h;

[0052] S3, 6kg liquid bisphenol A epoxy resin (E51), 0.5kg multifunctional glycidylamine epoxy resin (AG-80), 0.5kg solid epoxy resin (E12) are stirred and blended at 120°C to obtain a uniform mixed system. Then 0.3kg polyethersulfone, 0.3kg polyetherimide, 0.1kg hyperbranched polymer are added, stirred at 120°C for 2h to obtain a clear and transparent solution; the temperature is lowered to 80°C, the filler treated in step S1 is added, stirred for 50min, then the temperature is lowered to 60°C, 0.7kg dicyandiamide and 0.1kg urea accelerator are added, stirred for 30min, the temperature is further lowered to 40°C, and the heat-expandable microspheres obtained in step S2 are added to obtain a resin matrix with a viscosity of 50Pa·S at room temperature; a viscosity of 10Pa·S at 50°C, and a gel time of 120min; a viscosity of 0.5Pa·S at 100°C, and a gel time of 40min.

[0053] S4. Adjust the temperature to 50°C to make the viscosity of the resin matrix 10Pa·S. Use the coating process to control the surface density of the film by adjusting the coating speed to 0.5m / min and the gap between the rubber rollers to 0.5mm.

[0054] S5. Impregnate the adhesive film on the basalt fiber fabric, and obtain a low-temperature resistant thermal insulation prepreg with a resin matrix weight proportion of 30% by controlling the impregnation temperature at 45° C., adjusting the impregnation speed at 2 m / min, and the gap between the pressure rollers at 0.1 mm.

[0055] The obtained prepreg was cured according to the curing process of 100℃ / 1h+130℃ / 2h, and its tensile and bending properties at room temperature and -183℃ were tested, as shown in Table 1. From the data in Table 1, it can be concluded that the prepreg obtained in this scheme has relatively good low-temperature mechanical properties and meets the requirements of low-temperature mechanical applications.

[0056] The 4 layers of prepreg were laid on the surface of the composite panel preformed by commercial prepreg (T700 / 2511, Toray, Japan) by automatic fiber placement process, and cured according to the curing process of 100℃ / 1h+130℃ / 2h. The composite panel with an insulation layer was obtained by co-curing process (the schematic diagram of the structure after co-curing is shown in FIG. Figure 2 For comparison, the same commercial prepreg (T700 / 2511, Toray, Japan) was used to prepare composite panels without thermal insulation treatment according to the same curing process. The thermal conductivity results of the composite structures with and without thermal insulation prepreg after curing are shown in Figure 3 shown.

[0057] The above-mentioned thermal insulation prepreg and T700 / 2511 prepreg preparation process are used to manufacture a 0.5m diameter 、A composite tank with a thickness of 2.5 mm and filled with liquid nitrogen. The composite tank after insulation treatment (16 layers of T700 / 2511 prepreg + 4 layers of insulation prepreg) has a minimum outer surface temperature of -15°C 20 minutes after filling with liquid nitrogen, while the outer surface temperature of the tank without insulation treatment (20 layers of T700 / 2511 prepreg) is -110°C.

[0058] Example 2

[0059] A method for preparing a low-temperature resistant thermal insulation prepreg comprises the following steps:

[0060] S1. Take 1000 g of hollow glass microspheres with a particle size of 5 to 10 μm and 500 g of hollow glass microspheres with a particle size of 50 to 80 μm, add them to a 1 mol / L hydrochloric acid solution (5 L) and ultrasonically treat them for 1 h. Wash the hollow glass microspheres after ultrasonic treatment in distilled water, and then dry them in an oven at 80° C. for 50 min. Soak the dried hollow glass microspheres in a 10 g / L KH560 coupling agent methanol solution (2 L), ultrasonically treat them for 1 h, with an ultrasonic power of 2 kW, and then dry them at 70° C. for 2 h.

[0061] S2, take 300g of heat-expandable polyurethane microspheres and 300g of heat-expandable phenolic resin microspheres, stir and treat them in 0.5mol / L hydrochloric acid solution (4L) for 30min, wash the treated heat-expandable microspheres with acetone (5L) for several times, dry them in a 60℃ oven for 30min, soak the dried heat-expandable microspheres in a pre-prepared 10g / L KH560 anhydrous acetone solution (1L), ultrasonically treat for 1h, and then dry them at 60℃ for 30min;

[0062] S3, 4 kg of liquid bisphenol A epoxy resin (E51), 1.5 kg of solid epoxy resin (E22), 1 kg of multifunctional glycidylamine epoxy resin (AG-80), and 1 kg of solid epoxy resin (E12) were stirred and blended at 120°C to obtain a uniform mixed system. Then 0.4 kg of polyethersulfone, 0.3 kg of polyetherimide, and 0.15 kg of hyperbranched polymer (H30) were added, and stirred at 120°C for 2 hours to obtain a clear and transparent solution. The temperature was lowered to 80°C, the filler treated in step S1 was added, and the mixture was stirred for 50 min. The temperature was then lowered to 65°C, 0.5 kg of dicyandiamide, 0.1 kg of diaminodiphenyl sulfone and 0.1 kg of urea accelerator were added, the temperature was lowered to 50°C, and the microspheres treated in step S2 were added to obtain a resin matrix having a viscosity of 120 Pa·S at room temperature, a viscosity of 12 Pa·S at 70°C, and a gel time of 50 min, and a viscosity of 0.8 Pa·S at 120°C, and a gel time of 30 min.

[0063] S4. Adjust the temperature to 70°C to make the viscosity of the base resin 12Pa·S. Use the coating process to control the film surface density by adjusting the coating speed to 0.8m / min and the gap between the rubber rollers to 0.3mm.

[0064] S5. Impregnate the adhesive film on the basalt fiber fabric, and obtain a low-temperature resistant thermal insulation prepreg with a resin matrix weight proportion of 40% by controlling the impregnation temperature at 70° C., adjusting the impregnation speed at 2 m / min, and the gap between the pressure rollers at 0.2 mm.

[0065] The obtained prepreg was cured according to the curing process of 120°C / 3h, and its tensile and bending properties at room temperature and -183°C were tested, as shown in Table 1. From the data in Table 1, it can be concluded that the prepreg obtained in this scheme has relatively good low-temperature mechanical properties and meets the requirements of low-temperature mechanical applications.

[0066] The 4 layers of prepreg were laid on the surface of the composite panel preformed with commercial prepreg (T700 / 2511, Toray, Japan) by automatic fiber placement process, and cured at 120℃ / 3h. The composite panel with insulation layer was obtained by co-curing process (the schematic diagram of the structure after co-curing is shown in the figure). Figure 2 The thermal conductivity of the composite structure with thermal insulation prepreg after curing is shown in Figure 3 shown.

[0067] The composite tank with a diameter of 0.5m and a thickness of 2.5mm was manufactured using the above-mentioned insulating prepreg and T700 / 2511 prepreg preparation process, and liquid nitrogen was added. After the insulation treatment of the composite tank (16 layers of T700 / 2511 prepreg + 4 layers of insulating prepreg), the lowest outer surface temperature was -10°C 20 minutes after the liquid nitrogen was added, while the outer surface temperature of the tank without insulation treatment (20 layers of T700 / 2511 prepreg) was -110°C.

[0068] Table 1

[0069]

[0070]

[0071] Combined with the thermal conductivity test results of the thermal insulation prepreg in the specific embodiment of the present invention ( Figure 3 ), the thermal insulation effect test data of the composite material structure, and the low-temperature tensile strength and interlaminar shear strength test results of the thermal insulation prepreg (Table 1) indicate that the thermal insulation prepreg prepared by the technical solution proposed in the present invention can have excellent thermal insulation effect, and its low-temperature mechanical properties can also meet the application requirements of the composite material structure, and has a relatively good application effect.

[0072] The low-temperature resistant heat-insulating prepreg of the present invention is composed of a resin matrix and a fiber fabric. First, a light, high-strength, and heat-insulating inorganic heat-insulating filler and a heat-expanding microsphere are surface-treated, and then introduced into a resin to obtain a resin matrix with a good heat-insulating effect. Then, the resin matrix is ​​coated, impregnated with a fiber fabric, and other processes to obtain a low-temperature resistant and heat-insulating prepreg. The prepreg can be co-cured with a low-temperature composite tank, has the advantages of low-temperature resistance, low thermal conductivity, and good interface performance with composite materials, and does not require processing of the tank insulation layer, has the characteristics of high molding processing efficiency and low cost, and can further promote the development of the aerospace industry.

[0073] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A low temperature resistant thermal insulation prepreg, characterized in that: It is composed of a resin matrix and a fiber fabric, wherein the weight of the resin matrix accounts for 20-45% and the weight of the fiber fabric accounts for 55-80%.

2. The low temperature resistant thermal insulation prepreg according to claim 1, characterized in that: The resin matrix is ​​composed of epoxy resin, thermal expansion microspheres, inorganic thermal insulation filler, toughening agent, coupling agent and curing agent.

3. The low temperature resistant thermal insulation prepreg according to claim 2, characterized in that: The weight ratio of epoxy resin to the resin matrix is ​​50-90%; the epoxy resin is composed of one or more of bisphenol A epoxy resin, multifunctional glycidylamine epoxy resin, phenolic epoxy resin and aliphatic epoxy resin.

4. The low temperature resistant thermal insulation prepreg according to claim 2, characterized in that: The weight ratio of the heat-expandable microspheres to the resin matrix is ​​0.5-20%; the diameter of the heat-expandable microspheres is 10-100 μm, the expansion rate is 2-50 times, and the thermal expansion temperature is 80-120° C. The heat-expandable microspheres are composed of one or more of expandable polystyrene microspheres, phenolic resin microspheres, polyurethane microspheres, and acrylic ester microspheres.

5. The low temperature resistant thermal insulation prepreg according to claim 2, characterized in that: The weight ratio of the inorganic thermal insulation filler to the resin matrix is ​​0.5-20%; the diameter of the inorganic thermal insulation filler is 1-300 μm, and the density is 0.15-0.60 g / cm 3 ; The inorganic hollow material is composed of one or more of hollow glass microspheres, hollow silicon carbide microspheres, hollow alumina microspheres, hollow carbon microspheres, and hollow silica microspheres.

6. The low temperature resistant thermal insulation prepreg according to claim 2, characterized in that: The toughening agent accounts for 3-15% of the weight of the resin matrix, and the toughening agent is composed of one or more of polyethersulfone, polyetheretherketone, nano rubber particles, nylon, polyurethane, and polyetherimide.

7. The low temperature resistant thermal insulation prepreg according to claim 2, characterized in that: The amount of the coupling agent is 0.5-10% of the weight of the inorganic thermal insulation filler or the thermal expansion microsphere; the coupling agent is composed of one or more of the organic silane coupling agents KH550, KH560 and KH570.

8. The low temperature resistant thermal insulation prepreg according to claim 2, characterized in that: The dosage of the curing agent is 5-15% of the weight of the epoxy resin, and the curing agent is composed of one or more of diaminodiphenyl sulfone, dicyandiamide, polyether amine, triethylenetetramine, urea accelerator, diaminoimidazole triazine complex, and boron trifluoride monoethylamine.

9. The low temperature resistant heat insulating prepreg according to claim 2, characterized in that: The fiber fabric is one of basalt fiber, aramid fiber, alumina fiber and glass fiber.

10. A method for preparing the low temperature resistant thermal insulation prepreg according to any one of claims 1 to 9, characterized in that: Firstly, a coupling agent is used to treat the surface of heat-expandable microspheres and inorganic thermal insulation fillers to improve the interface bonding effect between the heat-expandable microspheres, inorganic thermal insulation fillers and resin. Then, the surface-treated heat-expandable microspheres and inorganic thermal insulation fillers are blended with epoxy resin, toughening agent and curing agent to obtain a resin matrix. Finally, the resin matrix is ​​subjected to coating and fiber fabric impregnation process to obtain a low-temperature resistant thermal insulation prepreg.

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