High-temperature-resistant bismaleimide resin system for wet-process winding forming and preparation method of high-temperature-resistant bismaleimide resin system

Abstract

The invention belongs to the field of composite materials, and particularly relates to a high-temperature-resistant bismaleimide resin for wet winding forming and a preparation method thereof, and the high-temperature-resistant bismaleimide resin comprises the following raw materials: a bismaleimide resin monomer, an epoxy resin monomer, a modifier, an ammonia curing agent, a diluent and a curing initiator. An allyl process modifier and an epoxy resin monomer are used as raw materials, an amine catalyst is selected, novel allyl phenoxy resin is synthesized to modify bismaleimide resin, BMI and an allyl compound are firstly subjected to diene addition to generate an intermediate, then the intermediate and double bonds of BMI are subjected to Diels-Adler reaction, a resin system with high crosslinking density is formed, and the bismaleimide resin with high crosslinking density is obtained. Meanwhile, a curing initiator is added to reduce the curing temperature of the modified BMI resin system, and a diluent is added to reduce the viscosity of the modified BMI resin system, so that the modified bismaleimide resin system which is good in toughness, low in viscosity and curing temperature and capable of keeping good heat resistance is obtained.

Description

Technical Field

[0001] This invention relates to the field of composite materials, and in particular to a high-temperature resistant bismaleimide resin system for wet winding molding and its preparation method. Background Technology

[0002] To reduce negative weight while maintaining shell strength, most large and medium-sized engines currently use composite material shells, manufactured using a wet winding process. The extreme performance requirements of next-generation weaponry place increasingly higher demands on the heat resistance of combustion chamber shells, such as temperatures exceeding 220°C. However, the glass transition temperatures (GTIs) of currently used wet winding resins are all below 200°C, making it difficult for conventional winding resins to meet these new performance requirements. Therefore, developing high-temperature resistant resins suitable for wet winding of rocket engine shells is of great significance. However, conventional epoxy resin systems suitable for wet winding of engine shells have relatively low temperature resistance, with GTIs typically below 130°C. Even existing specialized wet winding epoxy resins generally have GTIs below 200°C, failing to meet the needs of next-generation equipment. Therefore, improving the heat resistance of resins used in wet winding is an effective means to solve the above problems.

[0003] Bismaleimide resin (BMI) is a high-performance thermosetting resin widely used in aerospace, electronics, and automotive industries due to its excellent heat resistance, chemical resistance, electrical insulation, and mechanical properties. Despite its many superior properties, BMI resin has a high curing temperature, poor toughness, and high viscosity, which limits its use in wet winding. Patent CN117264357A discloses a low-viscosity, high-toughness bismaleimide resin for wet fiber winding, its preparation method, and its applications, prepared from modified bismaleimide resin, diluent, toughening agent, and accelerator. However, the bismaleimide resin obtained by this method still suffers from drawbacks such as high molding temperature and low crosslinking density leading to poor toughening effect, limiting its application range.

[0004] Therefore, it is of great significance to study a bismaleimide resin system for wet winding with low viscosity and medium temperature curing and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide a bismaleimide resin system suitable for wet winding molding of composite material shells. This system can effectively solve the problems of high curing temperature, poor toughness and high viscosity of bismaleimide resin, while having high temperature resistance.

[0006] The specific concept of this invention is as follows: A novel allyl phenolic resin is synthesized using allyl process modifiers and epoxy resin monomers as raw materials and an amine catalyst. The synthesized allyl phenolic resin is then used to modify bismaleimide resin. In the bismaleimide resin molecule, the carbonyl group is an electron-withdrawing group, while the carbon-carbon double bond is an electron-deficient structure. Therefore, a diene addition reaction is first performed, followed by a Diels-Adler reaction with the double bond of the bismaleimide resin, ultimately forming a resin system with a high crosslinking density. Simultaneously, a curing initiator is added to lower the curing temperature of the modified bismaleimide resin system, and a diluent is added to lower the viscosity of the modified BMI resin system, resulting in a modified bismaleimide resin system that possesses good toughness, low viscosity, low curing temperature, and maintains good heat resistance.

[0007] The specific technical solution of the present invention is as follows: A high-temperature resistant bismaleimide resin system for wet winding molding, the raw material composition by weight is: 80-100 parts of bismaleimide resin monomer, 20-30 parts of epoxy resin monomer, 10-15 parts of modifier, 50-60 parts of ammonia curing agent, 10-20 parts of diluent, and 5-8 parts of curing initiator.

[0008] Furthermore, the bismaleimide resin monomer is one or a combination of two of the following: diphenylmethane diamine type bismaleimide monomer and diphenyl ether diamine type bismaleimide monomer. When both monomers are selected for mixing, the mass percentage content of diphenyl ether diamine type bismaleimide monomer in the mixture is 40-60%.

[0009] Furthermore, the epoxy resin is one or more of the following: polyphenolic glycidyl ether epoxy resin, glycidyl ester epoxy resin, and glycidyl amine epoxy resin.

[0010] Further, the modifier is one or a combination of diallyl bisphenol A (CAS No. 1745-89-7), diallyl bisphenol A ether (CAS No. 3739-67-1), and diallyl bisphenol S (CAS No. 41481-66-7).

[0011] Furthermore, the ammonia-based curing agent is one or a combination of diaminodiphenylmethane (DDM) and diaminodiphenyl sulfone (DDS).

[0012] Furthermore, the diluent is one or a combination of two of toluene and diallyl phthalate.

[0013] Furthermore, the curing initiator is one or a combination of 2-ethyl-4-methylimidazole, triethylamine, triphenylphosphine, and dicumyl peroxide.

[0014] Furthermore, the amounts of each component are preferably expressed in parts by weight as follows: 80 parts of bismaleimide resin monomer, 20 parts of epoxy resin monomer, 10 parts of modifier, 50 parts of ammonia curing agent, 10 parts of diluent, and 5 parts of curing initiator. The bismaleimide resin monomer is a diphenylmethane diamine type bismaleimide monomer, the epoxy resin monomer is E51 epoxy resin, the modifier is diallyl bisphenol A, the ammonia curing agent is diaminodiphenyl sulfone (DDS), the diluent is diallyl phthalate, and the curing initiator is dicumyl peroxide.

[0015] In addition, the inventors have provided a method for preparing the above-mentioned high-temperature resistant bismaleimide resin system for wet winding molding, the specific steps of which are as follows: (1) Add epoxy resin monomer and modifier to the reaction vessel, heat and stir evenly. After reaching a certain reaction temperature, add a certain amount of catalyst and stir for a certain time to obtain a light yellow transparent modified epoxy resin monomer, namely allyl phenolic resin monomer. By selecting allyl process modifiers and suitable epoxy resins for molecular design, the heat resistance can be guaranteed while reducing the curing temperature of the bismaleimide resin system.

[0016] (2) Mix the bismaleimide resin monomer and the ammonia curing agent evenly, heat to a certain temperature for prepolymerization reaction, and then add the allylphenol oxy resin monomer obtained in step (1), react for a certain time, and obtain a mixture.

[0017] (3) Add the diluent and curing initiator to the mixture obtained in step (2), and stir evenly at a certain temperature to obtain a high-temperature resistant bismaleimide resin system with low viscosity and medium temperature curing.

[0018] Further, the reaction temperature in step (1) is 140-150℃, and the stirring time after adding the catalyst is 1-2h; the catalyst is tetramethylammonium bromide, and its amount is 1-3% of the weight of the modifier.

[0019] Furthermore, the prepolymerization reaction temperature in step (2) is 130-140℃, and the reaction time is 0.5-1h; after adding allylphenol oxy resin monomer, the reaction is carried out for 0.5-1h.

[0020] Furthermore, the reaction temperature in step (3) is 110-120℃ and the stirring time is 2-3h.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a high-temperature resistant bismaleimide resin system for wet winding molding, which uses synthesized allyl phenolic resin to modify BMI, so that the obtained resin system has high crosslinking density, good toughness and strength, and can maintain good heat resistance. The glass transition temperature is ≥220℃, the flexural strength of the casting is ≥200MPa, the viscosity range is 1100-1500 mPa•s, and the maximum curing temperature range is 170-180℃. Compared with conventional bismaleimide resin, the viscosity and maximum curing temperature are significantly reduced, while maintaining the glass transition temperature of conventional bismaleimide resin system.

[0022] (2) The diluent used in this invention improves the viscosity of the bismaleimide resin system, thereby enhancing its process adaptability in wet winding processes. The low-temperature curing initiator not only lowers the curing temperature of the bismaleimide resin system but also maintains its heat resistance. This high-temperature resistant bismaleimide resin system is not only suitable for large composite material engine housing structures but also has significant promotional value and engineering significance in other high-temperature rotating body structural components. Attached Figure Description

[0023] Figure 1 The DSC curve of the bismaleimide resin system prepared in Example 1 of this invention; Figure 2 The viscosity-time curve of the bismaleimide resin system prepared in Example 1 of this invention; Figure 3 The viscosity-time curve of the bismaleimide resin system prepared in Comparative Example 1 of this invention; Figure 4 The DSC curve is shown for the bismaleimide resin system prepared in Comparative Example 2 of this invention. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments; however, the technical solution of the present invention is not limited to the specific embodiments listed below. Any non-essential changes and adjustments made by those skilled in the art based on the above-described invention are within the scope of protection of the present invention. Unless otherwise specified, all raw materials are by weight.

[0025] Example 1: A high-temperature resistant bismaleimide resin system for wet winding molding, the raw material composition and preparation method are as follows: (1) Weigh 20g of E51 epoxy resin and 10g of diallyl bisphenol A and add them to a three-necked flask. Stir and heat with an electric stirrer. When the reaction solution reaches 150℃ and stabilizes, add 0.1g of tetramethylammonium bromide and stir at 150℃ for 1 h to obtain mixed solution a.

[0026] (2) Weigh 80g of diphenylmethane diamine type bismaleimide monomer and 50g of diaminodiphenyl sulfone (DDS), mix them evenly in a stirrer, gradually heat to 140℃ for prepolymerization reaction for 0.5h, then add the mixed solution a obtained in step (1), and continue the reaction for 1h to obtain mixed solution b.

[0027] (3) Weigh 10g of dipropylene phthalate and 5g of dicumyl peroxide and put them into the mixed solution b obtained in step (2). Stir at 110℃ for 2h to obtain high temperature resistant bismaleimide resin.

[0028] Figure 1 The DSC curve of the bismaleimide resin system prepared in Example 1 shows that its curing process is 120 ℃ 4h + 150 ℃ / 4h + 180 ℃ / 6h, indicating that the low-temperature initiator lowered the curing temperature of the bismaleimide resin system, which meets the requirements for medium-temperature curing.

[0029] Figure 2 The viscosity-time curve of the bismaleimide resin system prepared in Example 1 is shown. The viscosity of the prepared resin system after 6 hours is 1380 mPa•s, which meets the requirements for wet winding process.

[0030] The resin casting prepared from the resin composition of Example 1 has a flexural strength of 205.6 MPa and a glass transition temperature of 232.3 °C.

[0031] Example 2: A high-temperature resistant bismaleimide resin system for wet winding molding, the raw material composition and preparation method are as follows: (1) Weigh 25g of E51 epoxy resin and 13g of diallyl bisphenol A ether and add them to a three-necked flask. Stir and heat with an electric stirrer. When the reaction solution reaches 150℃ and stabilizes, add 0.2g of tetramethylammonium bromide and stir at 150℃ for 1 h to obtain mixed solution a.

[0032] (2) Weigh 90g of diphenylmethane diamine type bismaleimide monomer and 60g of diaminodiphenyl sulfone (DDS), mix them evenly in a stirrer, gradually heat to 140℃ for prepolymerization reaction for 1h, then add the mixed solution a obtained in step (1), continue the reaction for 30min, and obtain mixed solution b.

[0033] (3) Weigh 20g of diallyl phthalate and 8g of 2-ethyl-4-methylimidazole and put them into the mixed solution b obtained in step (2). Stir at 120℃ for 2h to obtain high temperature resistant bismaleimide resin.

[0034] The resin casting prepared from the resin composition of Example 2 has a flexural strength of 210.2 MPa, a glass transition temperature of 227.1 °C, a resin system viscosity of 1150 mPa•s after 6 h, and a curing process of 120 °C for 4 h + 150 °C / 4 h + 170 °C / 6 h.

[0035] Example 3: A high-temperature resistant bismaleimide resin system for wet winding molding, the raw material composition and preparation method are as follows: (1) Weigh 28g of TDE-85 epoxy resin and 10g of diallyl bisphenol A and add them to a three-necked flask. Stir and heat with an electric stirrer. When the reaction solution reaches 150℃ and stabilizes, add 0.1g of tetramethylammonium bromide and stir at 150℃ for 2 h to obtain mixed solution a.

[0036] (2) Weigh 100g of diphenyl ether diamine type bismaleimide monomer and 60g of diaminodiphenyl sulfone (DDS), mix them evenly in a stirrer, gradually heat to 140℃ for prepolymerization reaction for 0.5h, then add the mixed solution a obtained in step (1), continue the reaction for 1h, and obtain mixed solution b.

[0037] (3) Weigh 13g of dipropylene phthalate and 6g of dicumyl peroxide and put them into the mixed solution b obtained in step (2). Stir at 110°C for 3 hours to obtain high-temperature resistant bismaleimide resin.

[0038] The resin casting prepared from the resin composition of Example 3 has a flexural strength of 209.4 MPa, a glass transition temperature of 236.4 °C, a resin system viscosity of 1230 mPa•s after 6 h, and a curing process of 120 °C for 4 h + 150 °C / 4 h + 180 °C / 6 h.

[0039] Example 4: A high-temperature resistant bismaleimide resin system for wet winding molding, the raw material composition and preparation method are as follows: (1) Weigh 30g of E51 epoxy resin and 12g of diallyl bisphenol A and add them to a three-necked flask. Stir and heat with an electric stirrer. When the reaction solution reaches 150℃ and stabilizes, add 0.18g of tetramethylammonium bromide and stir at 150℃ for 1.5h to obtain mixed solution a.

[0040] (2) Weigh 90g of diphenylmethane diamine type bismaleimide monomer and 60g of diaminodiphenylmethane (DDM), mix them evenly in a stirrer, gradually heat to 140℃ for prepolymerization reaction for 1h, then add the mixed solution a obtained in step (1), continue the reaction for 30min, and obtain mixed solution b.

[0041] (3) Weigh 15g of dipropylene phthalate and 6g of dicumyl peroxide and put them into the mixed solution b obtained in step (2). Stir at 120°C for 2 hours to obtain high-temperature resistant bismaleimide resin.

[0042] The resin casting prepared from the resin composition of Example 4 has a flexural strength of 210.2 MPa, a glass transition temperature of 223.5 °C, a resin system viscosity of 1250 mPa•s after 6 h, and a curing process of 120 °C for 4 h + 150 °C for 4 h + 180 °C for 6 h.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that no diluent component was added in step (3), while all other operations were the same.

[0044] Figure 3 The viscosity-time curve of the bismaleimide resin system prepared for Comparative Example 1 was obtained. After testing, its viscosity after 6 hours was greater than 5000 mPa•s, which could not meet the requirements of the wet winding process. The glass transition temperature was 225℃, the flexural strength of the casting was 210MPa, and the curing process was 120℃ for 4 hours + 150℃ / 4 hours + 180℃ / 6 hours.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that no curing initiator component was added in step (3), while all other operations were the same.

[0046] Figure 4 The DSC curve of the bismaleimide resin system prepared for Comparative Example 2 shows that its curing process is 180 ℃ 4h + 200 ℃ / 4h + 250 ℃ / 6h, which does not meet the requirements for medium-temperature curing. The viscosity of the resin system after 6h is 1350 mPa•s, the glass transition temperature is 222℃, and the flexural strength of the casting is 207 MPa.

[0047] Comparative Example 3 The difference between this comparative example and Example 1 is that only 100g of diphenyl ether diamine type bismaleimide monomer was weighed, the resin was poured into a beaker and heated to melt, and the resin liquid was poured into a preheated mold with a release agent on the surface. The casting body was prepared by curing under the conditions of 180 ℃ / 4h + 200 ℃ / 4h + 250 ℃ / 6h.

[0048] The resin system was tested and found to have a viscosity greater than 5000 mPa•s after 6 hours, a glass transition temperature of 218 ℃, and a flexural strength of 145 MPa.

[0049] In summary, although some of the resin systems prepared in Comparative Examples 1-3 exhibited high glass transition temperatures and flexural strengths, their viscosity and curing conditions clearly did not meet the requirements for wet winding. Examples 1-4 successfully prepared bismaleimide resin systems with low viscosity, medium-temperature curing, excellent heat resistance, and significantly improved flexural strength. These systems meet the requirements for wet winding and show great promise for applications in aerospace, electronics, and automotive industries.

[0050] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A high-temperature resistant bismaleimide resin system for wet winding molding, characterized in that, Its raw material composition by mass parts is as follows: 80-100 parts of bismaleimide resin monomer, 20-30 parts of epoxy resin monomer, 10-15 parts of modifier, 50-60 parts of ammonia curing agent, 10-20 parts of diluent, and 5-8 parts of curing initiator.

2. The high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The bismaleimide resin monomer is one or a combination of two of the diphenylmethane diamine type bismaleimide monomer and the diphenyl ether diamine type bismaleimide monomer.

3. The high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The epoxy resin is one or more of the following: polyphenolic glycidyl ether epoxy resin, glycidyl ester epoxy resin, and glycidyl amine epoxy resin.

4. The high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The modifier is one or more of diallyl bisphenol A, diallyl bisphenol A ether, and diallyl bisphenol S.

5. The high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The ammonia-based curing agent is one or a combination of two of diaminodiphenylmethane and diaminodiphenyl sulfone.

6. The high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The diluent is one or a combination of two of toluene and diallyl phthalate.

7. The high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The curing initiator is one or a combination of 2-ethyl-4-methylimidazole, triethylamine, triphenylphosphine, and dicumyl peroxide.

8. The high-temperature resistant bismaleimide resin system for wet winding molding according to any one of claims 1-7, characterized in that, Its raw material composition by mass parts is as follows: 80 parts of bismaleimide resin monomer, 20 parts of epoxy resin monomer, 10 parts of modifier, 50 parts of ammonia curing agent, 10 parts of diluent, and 5 parts of curing initiator. The bismaleimide resin monomer is a diphenylmethane diamine type bismaleimide monomer, the epoxy resin monomer is E51 epoxy resin, the modifier is diallyl bisphenol A, the ammonia curing agent is diaminodiphenyl sulfone, the diluent is diallyl phthalate, and the curing initiator is dicumyl peroxide.

9. The method for preparing the high-temperature resistant bismaleimide resin system for wet winding molding according to claim 1, characterized in that, The specific steps are as follows: (1) Add epoxy resin monomer and modifier to the reaction vessel, heat and stir evenly, and after reaching a certain reaction temperature, add a certain amount of catalyst and stir for a certain time to obtain a light yellow transparent modified epoxy resin monomer, namely allylphenol oxy resin monomer. (2) Mix the bismaleimide resin monomer and the ammonia curing agent evenly, heat to a certain temperature for prepolymerization reaction, and then add the allylphenol oxy resin monomer obtained in step (1), react for a certain time, and obtain a mixture. (3) Add the diluent and curing initiator to the mixture obtained in step (2), and stir evenly at a certain temperature to obtain a high-temperature resistant bismaleimide resin system with low viscosity and medium temperature curing.

10. The method for preparing the high-temperature resistant bismaleimide resin system for wet winding molding according to claim 9, characterized in that, The reaction temperature in step (1) is 140-150℃, and the stirring time after adding the catalyst is 1-2 hours; the catalyst is tetramethylammonium bromide, and its dosage is 1-3% of the modifier. The prepolymerization reaction temperature in step (2) is 130-140℃; the reaction time is 0.5-1h; and the reaction time is 0.5-1h after adding allylphenol oxy resin monomer. The reaction temperature in step (3) is 110-120℃ and the stirring time is 2-3h.

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