Thermosetting epoxy resin for carbon fiber composite material

Abstract

The invention relates to the field of high polymer materials, in particular to thermosetting epoxy resin for a carbon fiber composite material, which is used for solving the problems that the existing thermosetting epoxy resin for the carbon fiber composite material is poor in heat resistance, chemical resistance and mechanical property; the use stability, the reliability and the service life of the carbon fiber composite material are influenced; according to the thermosetting epoxy resin, epoxy resin E-44 is used as a main raw material, performance enhancing resin is added into the epoxy resin E-44 for performance enhancement, the mechanical performance, heat resistance and chemical resistance of the thermosetting epoxy resin are remarkably improved, and the thermosetting epoxy resin can still keep good mechanical performance in a high-temperature environment and an acid-base corrosion environment; the preparation method of the thermosetting epoxy resin is simple in process, easy to control, low in cost, suitable for industrial production and good in market application prospect, and the application range of a carbon fiber composite material is widened, and application requirements in different fields can be met.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and in particular to a thermosetting epoxy resin for carbon fiber composite materials. Background Art

[0002] Carbon fiber composites, thanks to their exceptional properties such as high specific strength, high specific modulus, and low density, have found widespread application in numerous high-end applications. Thermosetting epoxy resins, commonly used as matrix resins for carbon fiber composites, directly impact the overall performance of the composite. However, traditional thermosetting epoxy resins have limitations in terms of heat resistance, chemical resistance, and mechanical properties.

[0003] In terms of heat resistance, the mechanical properties of traditional epoxy resins degrade rapidly in high-temperature environments, making them unsuitable for applications requiring high heat resistance. In terms of chemical resistance, traditional epoxy resins have poor tolerance to certain chemical media (such as strong acids, strong bases, and organic solvents), and are prone to swelling, dissolution, or chemical degradation, which affects the stability, reliability, and service life of carbon fiber composites. Therefore, the development of a thermosetting epoxy resin for carbon fiber composites is of great practical significance. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the purpose of the present invention is to provide a thermosetting epoxy resin for carbon fiber composite materials, which solves the problem that the existing thermosetting epoxy resin for carbon fiber composite materials has poor heat resistance, chemical resistance and mechanical properties, thereby affecting the stability, reliability and service life of the carbon fiber composite materials.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A thermosetting epoxy resin for carbon fiber composite materials, comprising the following components in parts by weight:

[0007] 90-100 parts of epoxy resin, 8-28 parts of performance enhancing resin, 1-3 parts of coupling agent, 42-56 parts of curing agent, 3-7 parts of toughening agent and 10-16 parts of diluent;

[0008] Wherein, the performance-enhancing resin is prepared by the following steps:

[0009] Step s1: 1,3-propylenediamine, 5-chlorosalicylaldehyde and anhydrous methanol are added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at a temperature of 0-5°C and a stirring rate of 200-300 r / min for 10-20 minutes, then the temperature is raised to 20-25°C and the stirring reaction is continued for 2-3 hours. After the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then recrystallized with anhydrous ethanol to obtain a hydroxyl chlorinated Schiff base;

[0010] Step s2: adding a hydroxyl-containing chlorinated Schiff base, triethylamine, perfluoro-1-octanol and anhydrous acetone to a three-necked flask equipped with a stirrer and a thermometer, stirring the reaction at a temperature of -10-0°C and a stirring rate of 200-300 r / min for 10-20 minutes, then heating the temperature to 30-35°C and continuing to stir the reaction for 4-5 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then rotary evaporated to remove the solvent, and then washed with distilled water 3-5 times, and then extracted with dichloromethane 2-3 times. The extracts are combined and rotary evaporated to remove the solvent to obtain a hydroxyl-containing fluorinated Schiff base;

[0011] Step s3: Add a hydroxyl fluorinated Schiff base, DOPO, and N,N-dimethylformamide to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser, introduce nitrogen protection, and stir the reaction at a temperature of 20-25° C. and a stirring rate of 200-300 r / min for 10-20 minutes, then raise the temperature to 50-55° C. and continue stirring the reaction for 1-2 hours, then raise the temperature to reflux and continue stirring the reaction for 6-8 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then rotary evaporated to remove the solvent, and then washed with anhydrous ethanol 3-5 times, and then placed in a vacuum drying oven and dried at a temperature of 50-55° C. for 6-8 hours to obtain a DOPO-modified hydroxyl fluorinated intermediate;

[0012] Step s4: Add the DOPO-modified hydroxyl fluorine-containing intermediate, benzyltriethylammonium chloride and epichlorohydrin into a three-necked flask equipped with a stirrer, a thermometer, an air duct and a reflux condenser, introduce nitrogen protection, and stir the reaction at a temperature of 20-25°C and a stirring rate of 200-300 r / min for 10-20 minutes. Then, raise the temperature to 110-120°C and continue stirring the reaction for 2-3 hours. Then, cool the temperature to 50-55°C and add sodium hydroxide solution and continue stirring the reaction for 5-6 hours. After the reaction, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then add it to dichloromethane, and then wash it with sodium bicarbonate solution and distilled water for 3-5 times in sequence. Then, dry it with anhydrous magnesium sulfate, and then vacuum filter it. The filtrate is rotary evaporated to remove the solvent to obtain a performance-enhanced resin.

[0013] As a further solution of the present invention: the usage ratio of the 1,3-propylenediamine, 5-chlorosalicylaldehyde and anhydrous methanol in step s1 is 10 mmol: 21-23 mmol: 40-50 mL.

[0014] As a further solution of the present invention: the usage ratio of the hydroxyl chlorine-containing Schiff base, triethylamine, perfluoro-1-octanol and anhydrous acetone in step s2 is 10 mmol: 25-30 mmol: 21-23 mmol: 60-70 mL.

[0015] As a further embodiment of the present invention: the usage ratio of the hydroxyl fluorine-containing Schiff base, DOPO and N,N-dimethylformamide in step s3 is 10 mmol:20 mmol:70-80 mL.

[0016] As a further embodiment of the present invention, the DOPO-modified hydroxyl fluorinated intermediate, benzyltriethylammonium chloride, epichlorohydrin and sodium hydroxide solution in step s4 are used in a ratio of 10 mmol: 0.05-0.07 g: 100-120 mmol: 25-30 mL.

[0017] As a further solution of the present invention: the mass fraction of the sodium hydroxide solution in step s4 is 35-40%.

[0018] As a further solution of the present invention: the mass fraction of the sodium bicarbonate solution in step s4 is 5-7%.

[0019] As a further solution of the present invention: the thermosetting epoxy resin is prepared by the following steps:

[0020] Step 1: Weigh 90-100 parts of epoxy resin, 8-28 parts of performance enhancing resin, 1-3 parts of coupling agent, 42-56 parts of curing agent, 3-7 parts of toughening agent and 10-16 parts of diluent according to weight and set aside;

[0021] Step 2: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 20-25°C and a stirring rate of 200-300r / min for 20-30min, then place in a vacuum drying oven, vacuum degas for 20-30min at a temperature of 100-110°C, then heat to 130-140°C and cure for 1-2h, then heat to 150-160°C and cure for 1-2h, then heat to 190-200°C and cure for 1-2h, then heat to 215-225°C and cure for 2-3h, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0022] As a further solution of the present invention: the epoxy resin is epoxy resin E-44.

[0023] As a further solution of the present invention: the coupling agent is silane coupling agent KH-560.

[0024] As a further solution of the present invention: the curing agent is curing agent DDS.

[0025] As a further solution of the present invention: the toughening agent is epoxy toughening agent WD-401.

[0026] As a further solution of the present invention: the diluent is glycidyl phenyl ether.

[0027] Beneficial effects of the present invention:

[0028] The present invention discloses a thermosetting epoxy resin for carbon fiber composite materials. The thermosetting epoxy resin for carbon fiber composite materials is obtained by stirring and mixing an epoxy resin, a performance-enhancing resin, a coupling agent, a curing agent, a toughening agent, and a diluent, followed by vacuum degassing, curing, and cooling to room temperature after curing. The thermosetting epoxy resin uses epoxy resin E-44 as a main raw material, to which the performance-enhancing resin is added for performance enhancement, thereby significantly improving the mechanical properties, heat resistance, and chemical resistance of the thermosetting epoxy resin, enabling the thermosetting epoxy resin to maintain good mechanical properties in high-temperature environments and acid-base corrosion environments, thereby broadening the application scope of the carbon fiber composite materials and meeting application requirements in different fields. Moreover, the preparation method of the thermosetting epoxy resin is simple in process, easy to control, low in cost, suitable for industrial production, and has good market application prospects.

[0029] In the process of preparing a thermosetting epoxy resin for carbon fiber composite materials, a performance-enhancing resin is first prepared, and 1,3-propylenediamine and 5-chlorosalicylaldehyde are reacted. The amino group on 1,3-propylenediamine reacts with the aldehyde group on 5-chlorosalicylaldehyde to form a Schiff base structure to obtain a hydroxyl chlorinated Schiff base. Then, the hydroxyl chlorinated Schiff base and perfluoro-1-octanol are reacted. The chlorine atom on the hydroxyl chlorinated Schiff base reacts with the hydroxyl group on perfluoro-1-octanol to introduce a large number of fluorine atoms to obtain a hydroxyl fluorinated Schiff base. Then, the hydroxyl fluorinated Schiff base and DOPO are reacted. The Schiff base structure on the hydroxyl fluorinated Schiff base reacts with the PH bond on DOPO to introduce phosphorus and a benzene ring to obtain a DOPO-modified hydroxyl fluorinated intermediate. Finally, the DOPO-modified hydroxyl fluorinated intermediate and epoxy chlorine are reacted. The hydroxyl groups on the DOPO-modified hydroxyl fluorinated intermediate react with epichlorohydrin to undergo a ring-opening-closing reaction, introducing epoxy groups to form epoxy resins, and obtaining performance-enhanced resins. The molecular structure of the performance-enhanced resin contains a large number of cyclic rigid structures, which give it excellent mechanical properties, and the molecular structure contains a large number of fluorine atoms, which give it excellent stability, and thus give it heat resistance and chemical resistance, which can improve the thermal stability of the molecular chain and can resist the erosion of chemical media such as strong acids, strong alkalis, and organic solvents. The molecular structure contains a large number of nitrogen and phosphorus elements, which give it excellent flame retardancy and temperature resistance. Therefore, adding the performance-enhanced resin to the thermosetting epoxy resin can significantly improve the mechanical properties, heat resistance and chemical resistance of the thermosetting epoxy resin. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0031] Example 1:

[0032] This embodiment is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0033] Step S1: 10 mmol 1,3-propylenediamine, 21 mmol 5-chlorosalicylaldehyde and 40 mL anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 0°C and a stirring rate of 200 r / min for 10 minutes, then the temperature was raised to 20°C and the stirring reaction was continued for 2 hours. After the reaction was completed, the reaction product was rotary evaporated to remove the solvent, and then recrystallized with anhydrous ethanol to obtain a hydroxyl chloro-Schiff base;

[0034] Step S2: 10 mmol of a hydroxyl-containing chlorinated Schiff base, 25 mmol of triethylamine, 21 mmol of perfluoro-1-octanol, and 60 mL of anhydrous acetone were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at -10°C and a stirring rate of 200 r / min for 10 minutes, and then the mixture was heated to 30°C and the stirring reaction was continued for 4 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then washed with distilled water 3 times, and then extracted with dichloromethane 2 times. The extracts were combined and the solvent was removed by rotary evaporation to obtain a hydroxyl-containing chlorinated Schiff base.

[0035] Step S3: 10 mmol of a hydroxyl fluorinated Schiff base, 20 mmol of DOPO, and 70 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser. The mixture was protected by nitrogen and stirred at 20° C. and a stirring rate of 200 r / min for 10 minutes. The mixture was then heated to 50° C. and stirred for 1 hour. The mixture was then heated to reflux and stirred for 6 hours. After the reaction, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed with anhydrous ethanol three times and then dried in a vacuum drying oven at 50° C. for 6 hours to obtain a DOPO-modified hydroxyl fluorinated intermediate.

[0036] Step S4: 10 mmol of DOPO-modified hydroxyl fluorinated intermediate, 0.05 g of benzyltriethylammonium chloride, and 100 mmol of epichlorohydrin were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube, and a reflux condenser. The mixture was protected by nitrogen and stirred at 20° C. and a stirring rate of 200 r / min for 10 minutes. The mixture was then heated to 110° C. and stirred for 2 hours. The mixture was then cooled to 50° C. and 25 mL of a 35% sodium hydroxide solution was added and stirred for 5 hours. After the reaction, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The mixture was then added to dichloromethane, washed three times with a 5% sodium bicarbonate solution and distilled water, dried over anhydrous magnesium sulfate, and vacuum filtered. The filtrate was rotary evaporated to remove the solvent to obtain a performance-enhanced resin.

[0037] Step S5: Weigh 90 parts of epoxy resin, 8 parts of performance enhancing resin, 1 part of coupling agent, 42 parts of curing agent, 3 parts of toughening agent, and 10 parts of diluent according to weight and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0038] Step S6: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 20°C and a stirring rate of 200r / min for 20 minutes, then place in a vacuum drying oven, vacuum degas for 20 minutes at a temperature of 100°C, then heat to 130°C and cure for 1 hour, then heat to 150°C and cure for 1 hour, then heat to 190°C and cure for 1 hour, then heat to 215°C and cure for 2 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0039] Example 2:

[0040] This embodiment is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0041] Step S1: 10 mmol 1,3-propylenediamine, 22 mmol 5-chlorosalicylaldehyde and 45 mL anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at 3°C and a stirring rate of 250 r / min for 15 minutes. The mixture was then heated to 22°C and stirred for 2.5 hours. After the reaction, the reaction product was rotary evaporated to remove the solvent, and then recrystallized from anhydrous ethanol to obtain a hydroxyl chloro-Schiff base;

[0042] Step S2: 10 mmol of a hydroxyl-containing chlorinated Schiff base, 28 mmol of triethylamine, 22 mmol of perfluoro-1-octanol, and 65 mL of anhydrous acetone were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at -5°C and a stirring rate of 250 r / min for 15 minutes, and then the mixture was heated to 32°C and stirred for 4.5 hours. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then washed with distilled water 4 times, and then extracted with dichloromethane 2 times. The extracts were combined and the solvent was removed by rotary evaporation to obtain a hydroxyl-containing chlorinated Schiff base.

[0043] Step S3: 10 mmol of a hydroxyl fluorinated Schiff base, 20 mmol of DOPO, and 75 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser. The mixture was protected by nitrogen and stirred at 22° C. and a stirring rate of 250 r / min for 15 minutes. The mixture was then heated to 52° C. and stirred for 1.5 hours. The mixture was then heated to reflux and stirred for 7 hours. After the reaction, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed with anhydrous ethanol four times and then dried in a vacuum drying oven at 52° C. for 7 hours to obtain a DOPO-modified hydroxyl fluorinated intermediate.

[0044] Step S4: 10 mmol of DOPO-modified hydroxyl fluorinated intermediate, 0.06 g of benzyltriethylammonium chloride and 110 mmol of epichlorohydrin were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at 22° C. and a stirring rate of 250 r / min for 15 minutes, and then the temperature was raised to 115° C. and the stirring reaction was continued for 2.5 hours. The temperature was then lowered to 52° C. and 28 mL of a 38% by mass sodium hydroxide solution was added and the stirring reaction was continued for 5.5 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then added to dichloromethane, and then washed four times with a 6% by mass sodium bicarbonate solution and distilled water, and then dried over anhydrous magnesium sulfate. The product was then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a performance-enhanced resin.

[0045] Step S5: Weigh 95 parts of epoxy resin, 18 parts of performance enhancing resin, 2 parts of coupling agent, 49 parts of curing agent, 5 parts of toughening agent and 13 parts of diluent according to weight parts and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0046] Step S6: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 22°C and a stirring rate of 250r / min for 25 minutes, then place in a vacuum drying oven, vacuum degas for 25 minutes at a temperature of 105°C, then heat to 135°C and cure for 1.5 hours, then heat to 155°C and cure for 1.5 hours, then heat to 195°C and cure for 1.5 hours, then heat to 220°C and cure for 2.5 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0047] Example 3:

[0048] This embodiment is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0049] Step S1: 10 mmol 1,3-propylenediamine, 23 mmol 5-chlorosalicylaldehyde and 50 mL anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 5°C and a stirring rate of 300 r / min for 20 minutes, then heated to 25°C and continued to stir for 3 hours. After the reaction, the reaction product was rotary evaporated to remove the solvent, and then recrystallized from anhydrous ethanol to obtain a hydroxyl chloro-Schiff base;

[0050] Step S2: 10 mmol of a hydroxyl-containing chlorinated Schiff base, 30 mmol of triethylamine, 23 mmol of perfluoro-1-octanol, and 70 mL of anhydrous acetone were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at 0° C. and a stirring rate of 300 r / min for 20 minutes, and then the mixture was heated to 35° C. and the stirring reaction was continued for 5 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then washed with distilled water 5 times, and then extracted with dichloromethane 3 times. The extracts were combined and the solvent was removed by rotary evaporation to obtain a hydroxyl-containing chlorinated Schiff base.

[0051] Step S3: 10 mmol of a hydroxyl fluorinated Schiff base, 20 mmol of DOPO, and 80 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser. The mixture was protected by nitrogen and stirred at 25° C. and a stirring rate of 300 r / min for 20 minutes. The mixture was then heated to 55° C. and stirred for 2 hours. The mixture was then heated to reflux and stirred for 8 hours. After the reaction, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed with anhydrous ethanol 5 times and then dried in a vacuum drying oven at 55° C. for 8 hours to obtain a DOPO-modified hydroxyl fluorinated intermediate.

[0052] Step S4: 10 mmol of DOPO-modified hydroxyl fluorinated intermediate, 0.07 g of benzyltriethylammonium chloride, and 120 mmol of epichlorohydrin were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser. The mixture was protected by nitrogen and stirred at 25° C. and a stirring rate of 300 r / min for 20 minutes. The mixture was then heated to 120° C. and stirred for 3 hours. The mixture was then cooled to 55° C. and 30 mL of a 40% sodium hydroxide solution was added and stirred for 6 hours. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then added to dichloromethane, and then washed five times with a 7% sodium bicarbonate solution and distilled water, and then dried over anhydrous magnesium sulfate. The mixture was then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a performance-enhanced resin.

[0053] Step S5: Weigh 100 parts of epoxy resin, 28 parts of performance enhancing resin, 3 parts of coupling agent, 56 parts of curing agent, 7 parts of toughening agent and 16 parts of diluent according to weight parts and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0054] Step S6: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 25°C and a stirring rate of 300r / min for 30 minutes, then place in a vacuum drying oven, vacuum degassing at a temperature of 110°C for 30 minutes, then heat to 140°C and cure for 2 hours, then heat to 160°C and cure for 2 hours, then heat to 200°C and cure for 2 hours, then heat to 225°C and cure for 3 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0055] Comparative Example 1:

[0056] This comparative example is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0057] Step S1: Weigh 100 parts of epoxy resin, 3 parts of coupling agent, 56 parts of curing agent, 7 parts of toughening agent and 16 parts of diluent according to weight and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0058] Step S6: Add epoxy resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix for 30 minutes at a temperature of 25°C and a stirring rate of 300r / min, then place in a vacuum drying oven, vacuum degassing for 30 minutes at a temperature of 110°C, then heat to 140°C and cure for 2 hours, then heat to 160°C and cure for 2 hours, then heat to 200°C and cure for 2 hours, then heat to 225°C and cure for 3 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0059] Comparative Example 2:

[0060] This comparative example is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0061] Step S1: 10 mmol 1,3-propylenediamine, 23 mmol 5-chlorosalicylaldehyde and 50 mL anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 5°C and a stirring rate of 300 r / min for 20 minutes, then heated to 25°C and continued to stir for 3 hours. After the reaction, the reaction product was rotary evaporated to remove the solvent, and then recrystallized from anhydrous ethanol to obtain a hydroxyl chloro-Schiff base;

[0062] Step S2: 10 mmol of hydroxyl chlorinated Schiff base, 0.07 g of benzyltriethylammonium chloride and 120 mmol of epichlorohydrin were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at a temperature of 25 ° C. and a stirring rate of 300 r / min for 20 minutes, and then the temperature was raised to 120 ° C. and the stirring reaction was continued for 3 hours. The temperature was then lowered to 55 ° C. and 30 mL of a 40% sodium hydroxide solution was added and the stirring reaction was continued for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then added to dichloromethane, and then washed with a 7% sodium bicarbonate solution and distilled water for 5 times, and then dried over anhydrous magnesium sulfate. After vacuum filtration, the filtrate was rotary evaporated to remove the solvent to obtain a performance-enhanced resin;

[0063] Step S3: Weigh 100 parts of epoxy resin, 28 parts of performance enhancing resin, 3 parts of coupling agent, 56 parts of curing agent, 7 parts of toughening agent and 16 parts of diluent according to weight and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0064] Step S4: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 25°C and a stirring rate of 300r / min for 30 minutes, then place in a vacuum drying oven, vacuum degassing at a temperature of 110°C for 30 minutes, then heat to 140°C and cure for 2 hours, then heat to 160°C and cure for 2 hours, then heat to 200°C and cure for 2 hours, then heat to 225°C and cure for 3 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0065] Comparative Example 3:

[0066] This comparative example is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0067] Step S1: 10 mmol 1,3-propylenediamine, 23 mmol 5-chlorosalicylaldehyde and 50 mL anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 5°C and a stirring rate of 300 r / min for 20 minutes, then heated to 25°C and continued to stir for 3 hours. After the reaction, the reaction product was rotary evaporated to remove the solvent, and then recrystallized from anhydrous ethanol to obtain a hydroxyl chloro-Schiff base;

[0068] Step S2: 10 mmol of a hydroxyl-containing chlorinated Schiff base, 30 mmol of triethylamine, 23 mmol of perfluoro-1-octanol, and 70 mL of anhydrous acetone were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at 0° C. and a stirring rate of 300 r / min for 20 minutes, and then the mixture was heated to 35° C. and the stirring reaction was continued for 5 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then washed with distilled water 5 times, and then extracted with dichloromethane 3 times. The extracts were combined and the solvent was removed by rotary evaporation to obtain a hydroxyl-containing chlorinated Schiff base.

[0069] Step S3: 10 mmol of a hydroxyl fluorine-containing Schiff base, 0.07 g of benzyltriethylammonium chloride, and 120 mmol of epichlorohydrin were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser. Nitrogen protection was introduced, and the mixture was stirred at 25° C. and a stirring rate of 300 r / min for 20 minutes. The mixture was then heated to 120° C. and stirred for 3 hours. The mixture was then cooled to 55° C. and 30 mL of a 40% sodium hydroxide solution was added and stirred for 6 hours. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then added to dichloromethane, and then washed 5 times with a 7% sodium bicarbonate solution and distilled water, and then dried over anhydrous magnesium sulfate. The mixture was then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a performance-enhanced resin.

[0070] Step S4: Weigh 100 parts of epoxy resin, 28 parts of performance enhancing resin, 3 parts of coupling agent, 56 parts of curing agent, 7 parts of toughening agent and 16 parts of diluent according to weight and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0071] Step S5: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 25°C and a stirring rate of 300r / min for 30 minutes, then place in a vacuum drying oven, vacuum degassing at a temperature of 110°C for 30 minutes, then heat to 140°C and cure for 2 hours, then heat to 160°C and cure for 2 hours, then heat to 200°C and cure for 2 hours, then heat to 225°C and cure for 3 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0072] Comparative Example 4:

[0073] This comparative example is a method for preparing a thermosetting epoxy resin for carbon fiber composite materials, comprising the following steps:

[0074] Step S1: 10 mmol 1,3-propylenediamine, 23 mmol 5-chlorosalicylaldehyde and 50 mL anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred at 5°C and a stirring rate of 300 r / min for 20 minutes, then heated to 25°C and continued to stir for 3 hours. After the reaction, the reaction product was rotary evaporated to remove the solvent, and then recrystallized from anhydrous ethanol to obtain a hydroxyl chloro-Schiff base;

[0075] Step S2: 10 mmol of a hydroxyl-containing chlorine-containing Schiff base, 20 mmol of DOPO, and 80 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a reflux condenser. The mixture was protected by nitrogen and stirred at 25° C. and a stirring rate of 300 r / min for 20 minutes. The mixture was then heated to 55° C. and stirred for 2 hours. The mixture was then heated to reflux and stirred for 8 hours. After the reaction, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed with anhydrous ethanol 5 times, and then placed in a vacuum drying oven and dried at 55° C. for 8 hours to obtain a DOPO-modified hydroxyl-containing chlorine-containing intermediate.

[0076] Step S3: 10 mmol of DOPO-modified hydroxyl chlorine-containing intermediate, 0.07 g of benzyltriethylammonium chloride and 120 mmol of epichlorohydrin were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at 25° C. and a stirring rate of 300 r / min for 20 minutes, and then the temperature was raised to 120° C. and the stirring reaction was continued for 3 hours. The temperature was then lowered to 55° C. and 30 mL of a 40% by mass sodium hydroxide solution was added and the stirring reaction was continued for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The product was then added to dichloromethane, and then washed with a 7% by mass sodium bicarbonate solution and distilled water five times in sequence. The product was then dried over anhydrous magnesium sulfate and vacuum filtered. The filtrate was rotary evaporated to remove the solvent to obtain a performance-enhanced resin.

[0077] Step S4: Weigh 100 parts of epoxy resin, 28 parts of performance enhancing resin, 3 parts of coupling agent, 56 parts of curing agent, 7 parts of toughening agent and 16 parts of diluent according to weight and set aside; the epoxy resin is epoxy resin E-44; the coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS; the toughening agent is epoxy toughening agent WD-401; and the diluent is glycidyl phenyl ether;

[0078] Step S5: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 25°C and a stirring rate of 300r / min for 30 minutes, then place in a vacuum drying oven, vacuum degassing at a temperature of 110°C for 30 minutes, then heat to 140°C and cure for 2 hours, then heat to 160°C and cure for 2 hours, then heat to 200°C and cure for 2 hours, then heat to 225°C and cure for 3 hours, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

[0079] The thermosetting epoxy resins for carbon fiber composite materials of Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests in accordance with GBT2567-2008 to obtain tensile strength. The samples were subjected to thermogravimetric analysis using a TG 209 F1 thermogravimetric analyzer (test conditions: test temperature range 30-800°C, nitrogen atmosphere, heating rate 10°C / min, air flow rate 20 mL / min) to obtain 5% thermal weight loss temperature. The test results are shown in the following table:

[0080]

[0081] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Examples 1-4, it can be seen that the thermosetting epoxy resin for carbon fiber composite materials of the present application has excellent mechanical properties, heat resistance and chemical resistance.

[0082] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0083] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the scope of protection of the present invention.

Claims

1. A thermosetting epoxy resin for carbon fiber composite materials, characterized in that: It comprises the following components in parts by weight: 90-100 parts of epoxy resin, 8-28 parts of performance enhancing resin, 1-3 parts of coupling agent, 42-56 parts of curing agent, 3-7 parts of toughening agent and 10-16 parts of diluent; Wherein, the performance-enhancing resin is prepared by the following steps: Step s1: stirring 1,3-propylenediamine, 5-chlorosalicylaldehyde and anhydrous methanol to react, and after the reaction, rotary evaporating the reaction product, and then recrystallizing it to obtain a hydroxyl chlorinated Schiff base; Step s2: stirring a hydroxyl-containing chlorine-containing Schiff base, triethylamine, perfluoro-1-octanol, and anhydrous acetone to react. After the reaction, the reaction product is cooled, then rotary evaporated, washed, extracted, and the extract is rotary evaporated to obtain a hydroxyl-containing fluorine-containing Schiff base. Step s3: stirring a hydroxyl fluorinated Schiff base, DOPO, and N,N-dimethylformamide to react. After the reaction, the reaction product is cooled, rotary evaporated, washed, and dried to obtain a DOPO-modified hydroxyl fluorinated intermediate. Step s4: The DOPO-modified hydroxyl fluorinated intermediate, benzyltriethylammonium chloride, and epichlorohydrin are stirred for reaction, and then sodium hydroxide solution is added and the stirring reaction is continued. After the reaction is completed, the reaction product is cooled, rotary evaporated, and then added to dichloromethane, followed by washing and drying, and then vacuum filtering. The filtrate is rotary evaporated to obtain a performance-enhanced resin.

2. The thermosetting epoxy resin for carbon fiber composite materials according to claim 1, characterized in that: The usage ratio of the 1,3-propylenediamine, 5-chlorosalicylaldehyde and anhydrous methanol in step s1 is 10 mmol: 21-23 mmol: 40-50 mL.

3. The thermosetting epoxy resin for carbon fiber composite materials according to claim 1, characterized in that: The usage ratio of the hydroxyl chlorine-containing Schiff base, triethylamine, perfluoro-1-octanol and anhydrous acetone in step s2 is 10 mmol: 25-30 mmol: 21-23 mmol: 60-70 mL.

4. The thermosetting epoxy resin for carbon fiber composite materials according to claim 1, characterized in that: The usage ratio of the hydroxyl fluorine-containing Schiff base, DOPO and N,N-dimethylformamide in step s3 is 10 mmol:20 mmol:70-80 mL.

5. The thermosetting epoxy resin for carbon fiber composite materials according to claim 1, characterized in that: In step s4, the usage ratio of the DOPO-modified hydroxyl fluorinated intermediate, benzyltriethylammonium chloride, epichlorohydrin and sodium hydroxide solution is 10 mmol: 0.05-0.07 g: 100-120 mmol: 25-30 mL.

6. The thermosetting epoxy resin for carbon fiber composite materials according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution in step s4 is 35-40%.

7. The thermosetting epoxy resin for carbon fiber composite materials according to claim 1, characterized in that: The thermosetting epoxy resin is prepared by the following steps: Step 1: Weigh 90-100 parts of epoxy resin, 8-28 parts of performance enhancing resin, 1-3 parts of coupling agent, 42-56 parts of curing agent, 3-7 parts of toughening agent and 10-16 parts of diluent according to weight and set aside; Step 2: Add epoxy resin, performance enhancing resin, coupling agent, curing agent, toughening agent and diluent to a mixer, stir and mix at a temperature of 20-25°C and a stirring rate of 200-300r / min for 20-30min, then place in a vacuum drying oven, vacuum degas for 20-30min at a temperature of 100-110°C, then heat to 130-140°C and cure for 1-2h, then heat to 150-160°C and cure for 1-2h, then heat to 190-200°C and cure for 1-2h, then heat to 215-225°C and cure for 2-3h, cool to room temperature after curing to obtain a thermosetting epoxy resin for carbon fiber composite materials.

8. The thermosetting epoxy resin for carbon fiber composite materials according to claim 7, characterized in that: The epoxy resin is epoxy resin E-44.

9. The thermosetting epoxy resin for carbon fiber composite materials according to claim 7, characterized in that: The coupling agent is silane coupling agent KH-560; the curing agent is curing agent DDS.

10. The thermosetting epoxy resin for carbon fiber composite materials according to claim 7, characterized in that: The toughening agent is epoxy toughening agent WD-401; the diluent is glycidyl phenyl ether.

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