Liquid oxygen compatible prepreg epoxy resin composition and preparation method thereof, prepreg and application

Abstract

The invention belongs to the technical field of resin-based composite materials, and particularly relates to a liquid oxygen compatible prepreg epoxy resin composition, a preparation method thereof, a prepreg and application. The liquid oxygen compatible prepreg epoxy resin composition comprises the following raw materials: phosphorus-containing epoxy resin, solid epoxy resin, liquid epoxy resin, a curing agent and an accelerant. The phosphorus-containing epoxy resin similar to the solid epoxy resin and the liquid epoxy resin in structure is introduced into the solid epoxy resin and the liquid epoxy resin in a simple physical blending mode, the raw material ratio is reasonably controlled, dicyandiamide serves as a curing agent, organic urea or derivatives of the organic urea serve as an accelerant, liquid oxygen compatibility and prepreg forming process requirements are met, and the preparation method is suitable for large-scale production. The requirement for actually manufacturing the composite material liquid oxygen storage tank is met, the working life is long, and it is guaranteed that the prepreg can be prepared in a high-quality mode; and in a freezer at the temperature of-18 DEG C, the storage life can reach more than 4 months. The operation is simple and convenient, and the problems of precipitation caused by physical blending of a modifier and complicated process caused by chemical modification are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of resin-based composite materials, and in particular relates to a liquid oxygen compatible prepreg epoxy resin composition and a preparation method thereof, a prepreg and an application thereof. Background Art

[0002] The use of lightweight, high-strength, corrosion-resistant, and well-designed carbon fiber reinforced epoxy resin-based composite materials to manufacture launch vehicle liquid oxygen tanks can achieve a significant reduction in rocket structure weight and an increase in carrying capacity. However, on the one hand, the incompatibility of the epoxy resin matrix in the composite material with liquid oxygen has restricted the development of composite liquid oxygen tanks. At present, most researchers use special elements such as bromine, phosphorus, and nitrogen to improve the liquid oxygen compatibility of epoxy resin. Chinese patent CN103467923A discloses a method for preparing an epoxy resin material compatible with liquid oxygen. The invention prepares a liquid oxygen-compatible epoxy resin by adding a flame retardant to the epoxy resin, but this method is a physical blending method, and the resin system will precipitate when left for a long time, thereby affecting the performance of the resin. Chinese patent CN115141465A also discloses an epoxy resin system compatible with liquid oxygen and a preparation method thereof. This invention obtains liquid oxygen-compatible epoxy resin by adding a synthetic phosphorus-nitrogen flame retardant to the epoxy resin. However, the steps for synthesizing the modifier in this method are cumbersome, and the curing process is complicated (100°C / 1h+120°C / 1h+140°C / 1h+160°C / 1h+180°C / 1h+200°C / 1h), which increases the difficulty of preparing the liquid oxygen-compatible resin system.

[0003] On the other hand, the processability of the resin matrix is ​​also an urgent problem to be solved. The molding processes of composite tanks mainly include winding molding process and prepreg molding process. Among them, the winding molding process has the following disadvantages: (1) When the conventional fiber winding process is used to process the pressure vessel with lining, the lining is difficult to remove; the unlined fiber winding process is only suitable for manufacturing special components, such as building structures. If new components need to be produced, the cost of readjustment is very high, and the programming cost is also high; (2) Fiber winding is limited to convex parts, which cannot meet the needs of other special-shaped components, and limits the design freedom of fiber direction; (3) There will be a phenomenon of cross-over and overlap of the filament bundles, which will cause protrusions in the local area, affecting the strength of the component and the aesthetics of the product. Therefore, this process is currently difficult to meet the molding and processing of unlined composite tanks.

[0004] Prepreg molding is achieved with the help of automatic fiber placement technology. Automatic fiber placement technology is suitable for the molding and processing of complex components with large curvatures, and can ensure the quality of the finished product. Prepreg is to impregnate continuous fibers or fiber fabrics under the condition of accurately controlling the resin matrix, and through certain treatment, it is prepared into a material with a certain storage period at room temperature, which can be directly used in the manufacture of composite materials. At present, the methods for preparing prepregs mainly include solution impregnation method and hot melt impregnation method. The preparation of prepregs by solution impregnation method has the disadvantages of complicated preparation process, low preparation efficiency, environmental pollution and health hazards, difficult to accurately control the resin content, and unstable product quality and performance. The process flow of preparing prepregs by hot melt method is relatively simple. It is not affected by solvent volatilization during the melting process of resin, and can more accurately control the content and uniformity of resin, and can more evenly impregnate fibers or fabrics, which is conducive to improving the quality and performance stability of the final composite product.

[0005] Therefore, along with the development of prepreg preparation technology, solution impregnation method has been gradually replaced by hot melt impregnation method.At present, hot melt prepreg epoxy resin is mainly prepared by adjusting the ratio of liquid epoxy resin, solid epoxy resin, curing agent, accelerator and filler (toughener, glass microsphere, nano material etc.).Chinese patent (CN103467923A and CN115141465A) discloses epoxy resin system compatible with liquid oxygen, but these resin systems do not meet prepreg forming process, and cannot be used for actual manufacturing composite material liquid oxygen tank.Chinese patent CN106687495A discloses a kind of epoxy resin composition for fiber reinforced composite material and its manufacture method, prepreg and honeycomb board, the invention utilizes the reactant obtained by the reaction of phosphorus-containing epoxy resin and amino-terminated nitrile rubber containing phosphorus atom in skeleton, other epoxy resins, curing agent and accelerator beyond phosphorus-containing epoxy resin to obtain flame-retardant epoxy resin composition and its prepreg, but does not point out that resin combination is compatible with liquid oxygen. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a liquid oxygen compatible prepreg epoxy resin composition and its preparation method, prepreg and application. By introducing a phosphorus-containing epoxy resin with a similar structure to the epoxy resin in a simple physical blending method, the precipitation caused by the physical blending flame retardant and the complicated process caused by chemical modification are solved. In addition, by reasonably controlling the raw material ratio, supplemented with dicyandiamide as a curing agent and organic urea as an accelerator, the composition can meet the process requirements of prepreg molding under the premise of meeting liquid oxygen compatibility, and has a long service life. The technical solution adopted is:

[0007] A liquid oxygen compatible prepreg epoxy resin composition comprises raw materials by weight including 10-40 parts of phosphorus-containing epoxy resin, 30-40 parts of solid epoxy resin, 30-40 parts of liquid epoxy resin, 5-10 parts of curing agent and 1-3 parts of accelerator.

[0008] Preferably, the raw materials include 20 parts of phosphorus-containing epoxy resin, 40 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 7 parts of curing agent, and 1 part of accelerator.

[0009] A method for preparing a liquid oxygen compatible prepreg epoxy resin composition comprises the following steps:

[0010] (1) placing a phosphorus-containing epoxy resin, a solid epoxy resin and a liquid epoxy resin in a reaction kettle at 80 to 110° C. and mixing them for 0.5 to 2 hours under mechanical stirring until the resins are uniformly mixed;

[0011] (2) cooling to 70-90° C., adding a curing agent, and mixing under mechanical stirring for 1-2 hours until the curing agent is uniformly mixed in the resin system prepared in step (2);

[0012] (3) maintaining the temperature at 70-90° C., adding an accelerator, and mechanically stirring for 5-10 minutes to uniformly mix the accelerator and the resin system obtained in step (3), thereby obtaining a liquid oxygen compatible prepreg epoxy resin composition.

[0013] Preferably, the curing procedure of the liquid oxygen compatible prepreg epoxy resin composition is: 100°C / 1h+130-150°C / 2h+160-180°C / 2h.

[0014] Preferably, the phosphorus-containing epoxy resin is aryl diglycidyl phosphonate ether.

[0015] Preferably, the solid epoxy resin is a combination of one or more of bisphenol A epoxy resin and bisphenol S epoxy resin. Further preferably, it is bisphenol A glycidyl ether epoxy resin, and further preferably, it is E22 epoxy resin.

[0016] Preferably, the liquid epoxy resin is a combination of one or more of bisphenol A glycidyl ether, bisphenol F glycidyl ether, and alicyclic epoxy resin. As a further preference, the bisphenol A glycidyl ether epoxy resin is further preferably E51 epoxy resin.

[0017] Preferably, the curing agent is dicyandiamide, and its particle size is not greater than 5 microns; the accelerator is an organic urea or its derivative, and its particle size is not greater than 5 microns. For example, N'-(3,4-dichlorophenyl)-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, N,N"-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea), and an organic urea accelerator with the trade name HUA5200.

[0018] A prepreg is prepared by impregnating a liquid oxygen compatible prepreg epoxy resin composition into reinforcing fibers.

[0019] Preferably, the weight ratio of resin to reinforcing fiber is 1:2. First, the resin composition is heated to no higher than 90°C in the coating tank of the coating machine to form a resin film, and then the release paper is laid. According to the requirements of the prepreg resin content, the gap between the film rollers is adjusted to between 0.02 and 0.08 mm, and the corresponding film surface density is 25 to 200 g / m 2 , start the coating machine to prepare the resin film, and after the surface density of the film reaches the above range, cool and roll it to obtain a resin film with release paper on both sides; then draw the resin film from the upper and lower film rollers of the prepreg machine, with the reinforcing fiber located between the two layers of film, and pass through 2-3 groups of hot rolling rollers with a temperature of 80-90° C. on the prepreg machine in sequence to fully impregnate the resin film and the reinforcing fiber, and then cool, trim, coat, and roll it to obtain a prepreg; the resin content in the prepreg is controlled at 30-40wt%. Further preferably, the weight ratio of the resin to the reinforcing fiber is 1:2.

[0020] The prepreg of the present invention can be applied to composite liquid oxygen tanks. The prepreg can be used to make carbon fiber composite materials, and the carbon fiber composite materials can be used to make liquid oxygen tanks.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention introduces a phosphorus-containing epoxy resin with a similar structure to a solid epoxy resin and a liquid epoxy resin by a simple physical blending method. The phosphorus-containing epoxy resin is completely compatible with other epoxy resins, thereby improving the liquid oxygen compatibility of common epoxy resins. The operation is simple and convenient, and the problems of precipitation caused by a physical blending modifier and complicated processes caused by chemical modification are solved.

[0023] The invention reasonably controls the raw material ratio, uses dicyandiamide as a curing agent, and organic urea or its derivatives as an accelerator, so that the composition meets the process requirements of prepreg molding under the premise of meeting liquid oxygen compatibility, and has a long application period, thereby ensuring that high-quality prepreg can be prepared; and the storage period in a freezer at -18°C can reach more than 4 months.

[0024] The liquid oxygen compatible prepreg epoxy resin composition has both liquid oxygen compatibility and prepreg molding process requirements, and meets the requirements for actually manufacturing composite liquid oxygen tanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The rheological properties of the liquid oxygen compatible prepreg epoxy resin composition prepared by the present invention are shown in Figure 1, wherein (a) is the variable temperature rheological properties, and (b) is the isothermal rheological properties.

[0026] Figure 2This is a viscosity diagram of the liquid oxygen compatible prepreg epoxy resin composition prepared in the present invention at 70° C. after being stored for 4 months. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to specific embodiments. The raw materials used in the present invention, unless otherwise specified, can be purchased through conventional commercial channels.

[0028] Example 1

[0029] A liquid oxygen compatible prepreg epoxy resin composition comprises 20 parts of phosphorus-containing epoxy resin, 40 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 7 parts of curing agent and 1 part of accelerator.

[0030] The phosphorus-containing epoxy resin is phosphonic acid aryl diglycidyl ether, and its preparation method comprises the following steps:

[0031] (1) reacting 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide and epichlorohydrin under the action of a ring-opening catalyst; the ring-opening catalyst is selected from tetrabutylammonium bromide, and the amount of the ring-opening catalyst is 0.5 wt% based on the mass of the reactant 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide; the reaction conditions are: heating to 60° C. and mechanically stirring for 5 hours under nitrogen protection.

[0032] (2) Adding a ring-closing catalyst to the product obtained in step (1), and continuing the reaction until the solution is clear and transparent; the ring-closing catalyst is selected from sodium methoxide, and its concentration is 30wt.%, and the molar ratio of the ring-closing catalyst to the 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide is 2:1. The ring-closing catalyst is added drop by drop, and the addition time is 1 hour. The reaction conditions of this process are mechanical stirring at 65°C for 10 hours.

[0033] (3) adding ionized water to the product obtained in step (2), removing by-products in the organic phase, and post-treating to obtain aryl phosphonate diglycidyl ester ether.

[0034] The structural formula of phosphonic acid aryl diglycidyl ester ether is:

[0035]

[0036] The solid epoxy resin is E22 epoxy resin,

[0037] The liquid epoxy resin is E51 epoxy resin.

[0038] The curing agent is dicyandiamide, and its particle size is not more than 5 microns. Specifically, it is dicyandiamide with the trade name HS5850S, which is produced by Shanghai Luohe High-tech Materials Co., Ltd.

[0039] The accelerator is an organic urea or its derivatives, and its particle size is not greater than 5 microns. Specifically, it is an organic urea accelerator with the trade name HUA5200, produced by Shanghai Luhe High-tech Materials Co., Ltd.

[0040] A method for preparing a liquid oxygen compatible prepreg epoxy resin composition comprises the following steps:

[0041] (1) 20 parts of aryl diglycidyl phosphonate ether, 40 parts of E22 epoxy resin and 40 parts of E51 epoxy resin were placed in a reaction kettle at 100° C. and mixed for 1.5 hours under mechanical stirring until the resins were uniformly mixed;

[0042] (2) cooling to 70° C., adding dicyandiamide, and mixing under mechanical stirring for 1 hour until the curing agent is evenly mixed in the resin system prepared in step (2);

[0043] (3) maintaining the temperature at 70° C., adding an accelerator, and mechanically stirring for 5 minutes to uniformly mix the accelerator and the resin system obtained in step (3), thereby obtaining a liquid oxygen compatible prepreg epoxy resin composition.

[0044] The curing procedure of the liquid oxygen compatible prepreg epoxy resin composition is: 100°C / 1h+150°C / 2h+160°C / 2h.

[0045] A prepreg is prepared by impregnating a liquid oxygen compatible prepreg epoxy resin composition into reinforcing fibers.

[0046] The prepared liquid oxygen compatible prepreg epoxy resin composition was tested for variable temperature rheological properties at a temperature range of room temperature to 200°C. The results are as follows: Figure 1 As shown in (a), the gel temperature of the resin composition is 170°C. The isothermal rheological properties test was carried out at 70°C, 80°C and 90°C. The results are shown in Figure 1 (b) shows that the liquid oxygen compatible prepreg epoxy resin composition has a wide processing temperature range, and at a prepreg preparation temperature of 70-90°C, the viscosity meets the prepreg process requirements, and high-quality prepreg can be prepared.

[0047] like Figure 2 As shown, the viscosity of the liquid oxygen compatible prepreg epoxy resin composition at 70°C before and after 4 months of storage was tested. The viscosity after 4 months of storage is still within 15-18 Pa·s, which is not much different from the initial viscosity, indicating that the liquid oxygen compatible prepreg epoxy resin composition can be stored at -18°C for more than 4 months.

[0048] Preparation of epoxy resin cured product: The liquid oxygen compatible prepreg epoxy resin composition is degassed in a vacuum oven, poured into a mold, cured according to the procedure of 100°C / 1h+130°C / 2h+160°C / 2h, and then naturally cooled to room temperature.

[0049] Preparation of prepreg: Heat the resin composition to 80°C in the glue tank to form a glue film, then lay the release paper, adjust the gap between the glue film rollers to 0.05mm, start the coating machine to prepare the resin glue film, and make the surface density of the glue film reach 200g / m 2 , cooling and winding to obtain a resin film with release paper on both sides; then the resin film is drawn out from the upper and lower film rollers of the prepreg machine, the carbon fiber (T700-12K unidirectional tape) is located between the two layers of film, and passes through three groups of hot rollers with a temperature of 85°C on the prepreg machine in turn to fully impregnate the resin film and the reinforcing fiber, and then goes through the steps of cooling, trimming, laminating, and winding to obtain a prepreg; the resin content in the prepreg is controlled at 35wt%. The weight ratio of resin to reinforcing fiber is 1:2.

[0050] Preparation of carbon fiber composite material: The above prepreg is laid, and then composite cured to prepare carbon fiber composite material. The carbon fiber composite material is cured according to the procedure of 100℃ / 1h+130℃ / 2h+160℃ / 2h.

[0051] (1) Rheological properties test of epoxy resin composition

[0052] The thermodynamic and isothermal rheological properties of the resin composition were tested using a rheometer.

[0053] (2) Liquid oxygen compatibility test of epoxy resin cured product and carbon fiber composite material

[0054] The epoxy resin cured product and the carbon fiber composite material are cured into 20 discs with a diameter of 20 mm and a thickness of 2-3 mm. The liquid oxygen compatibility of the resin is tested according to ASTM G86-17. If there is no sensitivity reaction (such as sparks, charring, explosion, burning, etc.) in 20 impact tests, it means that the material is compatible with liquid oxygen. If a sensitivity reaction occurs once in 20 impact tests, 40 impact tests are performed again. If no sensitivity reaction occurs in 40 impact tests, it is also considered to be compatible with liquid oxygen. The liquid oxygen compatibility results of the resin are shown in Table 2, where IRS is expressed as the liquid oxygen sensitivity coefficient, and its calculation method is:

[0055] where w i is the weighting coefficient of different reactions, where w1 = 0.4 (carbon residue), w2 = 0.6 (spark), w3 = 0.9 (explosion), w4 = 1 (combustion); n iis the number of experimental phenomena. In addition, the smaller the IRS, the better the liquid oxygen compatibility of the material.

[0056] (3) Mechanical properties test of epoxy resin cured product and carbon fiber composite material

[0057] The tensile properties of resins and composites at room temperature and low temperature (-183°C) were tested on a universal testing machine according to GB / T 2567-2021 and ASTM D3039.

[0058] (4) Epoxy resin glass transition temperature (Tg) test

[0059] The Tg of epoxy resin was tested by dynamic thermomechanical analyzer.

[0060] Example 2

[0061] A liquid oxygen compatible prepreg epoxy resin composition comprises 25 parts of phosphorus-containing epoxy resin, 35 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 7 parts of curing agent and 1 part of accelerator.

[0062] According to the method of Example 1, a liquid oxygen compatible prepreg epoxy resin composition was prepared.

[0063] Other unmentioned places are the same as those in Example 1.

[0064] Preparation of epoxy resin cured product: After degassing the resin composition in a vacuum oven, pour it into a mold and cure it according to the procedure of 100°C / 1h+130°C / 2h+160°C / 2h, and then cool it naturally to room temperature.

[0065] Preparation of prepreg: Heat the resin composition to 80°C in the glue tank to form a glue film, then lay the release paper, adjust the gap between the glue film rollers to 0.05mm, start the coating machine to prepare the resin glue film, and make the surface density of the glue film reach 200g / m 2 , cooling and winding to obtain a resin film with release paper on both sides; then the resin film is drawn out from the upper and lower film rollers of the prepreg machine, the carbon fiber (T700-12K unidirectional tape) is located between the two layers of film, and passes through three groups of hot rollers with a temperature of 85°C on the prepreg machine in turn to fully impregnate the resin film and the reinforcing fiber, and then goes through the steps of cooling, trimming, laminating, and winding to obtain a prepreg; the resin content in the prepreg is controlled at 35wt%. The weight ratio of resin to reinforcing fiber is 1:2.

[0066] Preparation of carbon fiber composite material: The above prepreg is laid, and then composite cured to prepare carbon fiber composite material. The carbon fiber composite material is cured according to the procedure of 100℃ / 1h+130℃ / 2h+160℃ / 2h.

[0067] Example 3

[0068] A liquid oxygen compatible prepreg epoxy resin composition comprises 20 parts of phosphorus-containing epoxy resin, 40 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 8 parts of curing agent and 1.5 parts of accelerator.

[0069] According to the method of Example 1, a liquid oxygen compatible prepreg epoxy resin composition was prepared.

[0070] Other unmentioned places are the same as those in Example 1.

[0071] Preparation of epoxy resin cured product: After degassing the resin composition in a vacuum oven, pour it into a mold and cure it according to the procedure of 100°C / 1h+120°C / 2h+150°C / 2h, and then cool it naturally to room temperature.

[0072] Preparation of prepreg: Heat the resin composition to 80°C in the glue tank to form a glue film, then lay the release paper, adjust the gap between the glue film rollers to 0.05mm, start the coating machine to prepare the resin glue film, and make the surface density of the glue film reach 200g / m 2 , cooling and winding to obtain a resin film with release paper on both sides; then the resin film is drawn out from the upper and lower film rollers of the prepreg machine, the carbon fiber (T700-12K unidirectional tape) is located between the two layers of film, and passes through three groups of hot rollers with a temperature of 85°C on the prepreg machine in turn to fully impregnate the resin film and the reinforcing fiber, and then goes through the steps of cooling, trimming, laminating, and winding to obtain a prepreg; the resin content in the prepreg is controlled at 35wt%. The weight ratio of resin to reinforcing fiber is 1:2.

[0073] Preparation of carbon fiber composite material: The above prepreg is laid, and then composite cured to prepare carbon fiber composite material. The carbon fiber composite material is cured according to the procedure of 100℃ / 1h+120℃ / 2h+150℃ / 2h.

[0074] Comparative Example 1

[0075] An epoxy resin composition, wherein the raw materials include 60 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 7 parts of curing agent and 1 part of accelerator.

[0076] An epoxy resin composition was prepared according to the method of Example 1.

[0077] Other unmentioned places are the same as those in Example 1.

[0078] After testing, it was found that the prepared epoxy resin composition was incompatible with liquid oxygen.

[0079] Comparative Example 2

[0080] An epoxy resin composition, the raw materials of which include 5 parts of phosphorus-containing epoxy resin, 55 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 7 parts of curing agent and 1 part of accelerator.

[0081] An epoxy resin composition was prepared according to the method of Example 1.

[0082] Other unmentioned places are the same as those in Example 1.

[0083] After testing, it was found that the prepared epoxy resin composition was incompatible with liquid oxygen.

[0084] Comparative Example 3

[0085] An epoxy resin composition, wherein the raw materials include 20 parts of phosphorus-modified epoxy resin, 45 parts of solid epoxy resin, 35 parts of liquid epoxy resin, 7 parts of curing agent and 1 part of accelerator.

[0086] An epoxy resin composition was prepared according to the method of Example 1.

[0087] Other unmentioned places are the same as those in Example 1.

[0088] The preparation method of phosphorus-modified epoxy resin is as follows: 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide and E51 epoxy resin (mass ratio is 1:8.5) are placed in a three-necked flask, mechanically stirred at 180°C, and reacted for 1.5 hours to obtain phosphorus-modified epoxy resin, whose chemical structure is:

[0089]

[0090] The epoxy resin compositions of Examples 1-3 and Comparative Examples 1-3 (ie, liquid oxygen compatible prepreg epoxy resin compositions) and their cured products were tested. The test results are shown in Table 1.

[0091] Table 1 Comparison of properties of epoxy resin compositions and cured products of Examples 1-3 and Comparative Examples 1-3

[0092]

[0093] Table 2 Comparison of carbon fiber composite materials performance between Examples 1-3 and Comparative Examples 1-3

[0094]

[0095] As can be seen from the test results of Table 1, the viscosity of the epoxy resin composition in Examples 1, 2, and 3 is suitable, the storage period is more than 4 months, and the resin cured product is compatible with liquid oxygen, and the mechanical properties are excellent. At the same time, the carbon fiber composite material also shows excellent mechanical properties, which meets the use requirements in extreme environments such as liquid oxygen; while the product in Comparative Examples 1-3 has a relatively low viscosity at 70°C, although it also meets the process requirements of prepreg molding (<20000mPavs), it can be seen from Table 2 that the epoxy resin cured product in Comparative Example 1 is incompatible with liquid oxygen, which is due to the lack of phosphorus-containing epoxy resin in the resin composition; the amount of phosphorus-containing epoxy resin added to the epoxy resin composition in Comparative Example 2 is not enough, so the epoxy resin cured product is incompatible with liquid oxygen. The epoxy resin composition in Comparative Example 3 adds a phosphorus-containing modified resin, but the phosphorus content of the phosphorus-containing modified epoxy resin is lower than that of the phosphorus-containing epoxy resin, so the epoxy resin cured product is incompatible with liquid oxygen.

[0096] The liquid oxygen compatibility test results of the epoxy resin cured products of Examples 1-3 and Comparative Examples 1-3 are shown in Table 3.

[0097] Table 3 Comparison of the liquid oxygen compatibility test results of epoxy resin cured products of Examples 1-3 and Comparative Examples 1-3

[0098] Sample Carbon black / second Spark / time Burning / times Explosion / times Number of experiments IRS / % Example 1 0 0 0 0 20 0 Example 2 0 0 0 0 20 0 Example 3 0 0 0 0 20 0 Comparative Example 1 3 2 0 0 20 12 Comparative Example 2 4 1 0 0 20 11 Comparative Example 3 3 1 0 0 20 9

[0099] The liquid oxygen compatibility test results of the carbon fiber composite materials of Examples 1-3 and Comparative Examples 1-3 are shown in Table 4.

[0100] Table 4 Comparison of liquid oxygen compatibility test results of carbon fiber composite materials of Examples 1-3 and Comparative Examples 1-3

[0101] Sample Carbon black / second Spark / time Burning / times Explosion / times Number of experiments IRS / % Example 1 0 0 0 0 20 0 Example 2 0 0 0 0 20 0 Example 3 0 0 0 0 20 0 Comparative Example 1 0 2 0 0 20 6 Comparative Example 2 0 1 0 0 20 3 Comparative Example 3 0 1 0 0 20 3

[0102] In summary, the epoxy resin cured products and carbon fiber composite materials of Examples 1-3 have good compatibility with liquid oxygen.

[0103] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A liquid oxygen compatible prepreg epoxy resin composition, characterized in that: The resin composition comprises, by weight, 100 parts of epoxy resin mixture, 5-10 parts of curing agent, and 1-3 parts of accelerator; by weight of the epoxy resin mixture, the epoxy resin mixture is prepared by mixing 10-40 parts of phosphorus-containing epoxy resin, 30-40 parts of solid epoxy resin, and 30-40 parts of liquid epoxy resin.

2. A liquid oxygen compatible prepreg epoxy resin composition according to claim 1, characterized in that: The raw materials include 20 parts of phosphorus-containing epoxy resin, 40 parts of solid epoxy resin, 40 parts of liquid epoxy resin, 7 parts of curing agent and 1 part of accelerator.

3. A method for preparing a liquid oxygen compatible prepreg epoxy resin composition as claimed in claim 1 or 2, characterized in that: The steps include: (1) placing a phosphorus-containing epoxy resin, a solid epoxy resin and a liquid epoxy resin in a reaction kettle at 80 to 110° C. and mechanically stirring until the resins are uniformly mixed; (2) cooling to 70-90° C., adding a curing agent, and mechanically stirring until the curing agent is uniformly mixed in the resin system prepared in step (2); (3) maintaining the temperature at 70-90° C., adding an accelerator, and mechanically stirring to uniformly mix the accelerator and the resin system obtained in step (3), thereby obtaining a liquid oxygen compatible prepreg epoxy resin composition.

4. The method for preparing a liquid oxygen compatible prepreg epoxy resin composition according to claim 3, wherein the curing procedure of the liquid oxygen compatible prepreg epoxy resin composition is: 100°C / 1h+130-150°C / 2h+160-180°C / 2h.

5. The method for preparing a liquid oxygen compatible prepreg epoxy resin composition according to claim 3, characterized in that: The phosphorus-containing epoxy resin is phosphonic acid aryl diglycidyl ether.

6. The method for preparing a liquid oxygen compatible prepreg epoxy resin composition according to claim 3, characterized in that: The solid epoxy resin is a combination of one or more of bisphenol A epoxy resin and bisphenol S epoxy resin.

7. The method for preparing a liquid oxygen compatible prepreg epoxy resin composition according to claim 3, characterized in that: The liquid epoxy resin is a combination of one or more of bisphenol A glycidyl ether, bisphenol F glycidyl ether and alicyclic epoxy resin.

8. The method for preparing a liquid oxygen compatible prepreg epoxy resin composition according to claim 3, characterized in that: The curing agent is dicyandiamide, and its particle size is not greater than 5 microns; the accelerator is organic urea or its derivatives, and its particle size is not greater than 5 microns.

9. A prepreg, prepared using the liquid oxygen compatible prepreg epoxy resin composition according to claim 1 or 2 or 3-8, characterized in that: The liquid oxygen compatible prepreg epoxy resin composition is impregnated into the reinforcing fiber; the weight ratio of the liquid oxygen compatible prepreg epoxy resin composition to the reinforcing fiber is 1:

2.

10. Use of the prepreg according to claim 9 in a composite liquid oxygen tank.

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