Precursor-modified high-temperature-resistant self-curing epoxy resin matrix as well as preparation method and application thereof

Abstract

The invention provides a precursor-modified high-temperature-resistant self-curing epoxy resin matrix as well as a preparation method and application thereof, the self-curing epoxy resin matrix is obtained by mixing epoxy resin and polysilazane, and the mass ratio of the epoxy resin to the polysilazane is (2-5): 1. The precursor modified epoxy resin is synthesized through molecular design, and the temperature resistance level of a traditional epoxy resin system is improved by 100-200 DEG C by means of the excellent high temperature resistance of the organosilicon precursor; wherein polysilazane is a precursor with a main chain composed of silicon and nitrogen, the chemical reactivity is high, self-curing of a resin system can be achieved through a ring-opening reaction of an N-H bond and an epoxy group without adding a traditional amine curing agent, the proportion of the N-H bond in the epoxy resin system can be adjusted by adjusting the raw material ratio, and the self-curing performance of the epoxy resin system is improved. And adjusting the crosslinking density of the curing system so as to adjust the mechanical properties of the resin system.

Description

Technical Field

[0001] The invention belongs to the technical field of resin-based composite materials, and particularly relates to a precursor-modified high-temperature-resistant self-curing epoxy resin matrix, a preparation method and an application thereof. Background Art

[0002] The development of new resins with both high heat resistance and excellent processability is of great significance to the fields of aerospace, communications, and electronics. Traditional high-temperature resistant polymers usually have poor processing performance. As the requirements for polymer performance and processing conditions in related fields become increasingly stringent, there are currently few high-temperature resistant resins that meet the requirements. Epoxy resin is a type of thermosetting polymer material with excellent mechanical properties and high strength. It has been widely used in the field of composite material manufacturing. It has excellent processing performance and is the most common resin matrix used in aerospace structures. It is suitable for a variety of composite material molding processes. However, epoxy resins usually have poor heat resistance, which restricts the application of epoxy resins in new high-temperature resistant resins.

[0003] At present, the commonly used high temperature resistant matrix resins are mainly polyimide (PI), phthalonitrile (LB), bismaleimide (BMI) and cyanate ester (CE), etc., and there are few studies on the high temperature resistant modification of epoxy resin. Therefore, it is of great scientific significance and application value to prepare a high temperature resistant resin system with excellent processing performance, mechanical properties and high temperature resistance. Summary of the invention

[0004] In order to overcome the deficiencies in the prior art, the inventors have conducted intensive research and provided a precursor-modified high-temperature resistant self-curing epoxy resin and a preparation method thereof, which achieves a substantial improvement in the heat resistance of the resin while ensuring the mechanical properties of the epoxy resin. At the same time, it also has the excellent process performance of the epoxy resin system, thus meeting the mechanical, heat resistance and processability requirements of resin-based composite materials.

[0005] The present invention synthesizes the epoxy resin modified by the precursor through molecular design, and with the help of the excellent high temperature resistance of the organosilicon precursor, the temperature resistance level of the traditional epoxy resin system is increased by 100-200°C. Among them, polysilazane is a kind of precursor whose main chain is composed of silicon and nitrogen, and has high chemical reaction activity. By utilizing the ring-opening reaction of NH bonds and epoxy groups, the self-curing of the resin system can be achieved without adding traditional amine curing agents. By adjusting the raw material ratio, the proportion of NH bonds in the epoxy resin system can be adjusted, and the cross-linking density of the curing system can be adjusted, thereby adjusting the mechanical properties of the resin system.

[0006] The technical solution provided by the present invention is as follows:

[0007] In a first aspect, a precursor-modified high-temperature resistant self-curing epoxy resin matrix is ​​obtained by mixing epoxy resin and polysilazane, wherein the mass ratio of the epoxy resin to the polysilazane is 2 to 5:1.

[0008] In a second aspect, a precursor-modified high-temperature resistant self-curing epoxy resin matrix is ​​obtained by mixing and curing an epoxy resin and polysilazane, wherein the mass ratio of the epoxy resin to the polysilazane is 2 to 5:1.

[0009] In a third aspect, a method for preparing the precursor-modified high temperature resistant self-curing epoxy resin matrix according to the first aspect comprises the following steps:

[0010] Mix epoxy resin and polysilazane evenly at room temperature;

[0011] The mixed system is reacted at 70-80° C. under stirring conditions for 0.5-2 hours to obtain a high temperature resistant self-curing epoxy resin.

[0012] In a fourth aspect, a fiber-reinforced resin-based composite material uses fibers as reinforcements and the high-temperature-resistant self-curing epoxy resin matrix modified by the precursor described in the first aspect as a composite material matrix resin.

[0013] A fifth aspect provides an application of the precursor-modified high-temperature resistant self-curing epoxy resin matrix described in the first aspect as a coating material or a composite material matrix resin.

[0014] A precursor-modified high-temperature-resistant self-curing epoxy resin matrix and a preparation method and application thereof provided by the present invention have the following beneficial effects:

[0015] (1) The present invention provides a precursor-modified high-temperature resistant self-curing epoxy resin matrix and a preparation method thereof, wherein epoxy resin and polysilazane are used as raw materials to prepare the precursor-modified high-temperature resistant self-curing epoxy resin, the preparation process is simple, and no by-products are produced;

[0016] (2) The present invention provides a precursor-modified high-temperature resistant self-curing epoxy resin matrix and a preparation method thereof. From the perspective of molecular structure design, the high-temperature residual weight of the epoxy resin can be significantly increased by using polysilazane. After high-temperature sintering, SiC, Si3N4, etc. remain in the system, which can significantly improve the high-temperature resistance of the epoxy resin system.

[0017] (3) The present invention provides a precursor-modified high-temperature resistant self-curing epoxy resin matrix and a preparation method thereof. From the perspective of molecular structure design, the active -NH- bond in polysilazane undergoes a ring-opening reaction with the epoxy group. Due to the high chemical reactivity of polysilazane, curing time is saved. There is no need to mix the resin system with the curing agent to achieve self-curing, which saves processing time. Moreover, the curing reaction start time can be adjusted at any time according to needs.

[0018] (4) The present invention provides a precursor-modified high-temperature resistant self-curing epoxy resin matrix and a preparation method thereof. Liquid polysilazane is selected, and the viscosity of the system can be adjusted by adding the proportion. It has little effect on the processability of the resin system and the mechanical properties of the self-curing and post-curing system, and can take into account both high-temperature resistance and process performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The infrared spectra of the 830 epoxy resin (#1) in Example 1 and the obtained precursor-modified high temperature resistant epoxy resin before curing (#2) and after curing (#3);

[0020] Figure 2 Actual photo of the precursor-modified high temperature resistant epoxy resin 3;

[0021] Figure 3 This is a real photo of Comparative Example 1, and the substrate has cracks;

[0022] Figure 4 This is a photo of the comparative example 2, in which the substrate is foamed. DETAILED DESCRIPTION

[0023] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0024] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0025] The present invention provides a method for preparing a precursor-modified high-temperature resistant self-curing epoxy resin, comprising the following steps:

[0026] Mix epoxy resin and polysilazane evenly at room temperature;

[0027] The mixed system is reacted at 70-80° C. under stirring conditions for 0.5-2 hours to obtain a high temperature resistant self-curing epoxy resin.

[0028] Epoxy resin contains more than two epoxy groups; the main chain of polysilazane is -Si-N-Si-N- structure, and the side chain contains saturated groups, unsaturated groups and (or) hydrogen atoms. Polysilazane is used as a precursor of the matrix material for preparing ceramic-based composite materials by the PIP method. After high-temperature pyrolysis, the ceramic yield can reach 60% or even higher. It has excellent high-temperature stability and can effectively improve the high-temperature resistance of the epoxy resin system. The active -NH- bond in polysilazane undergoes a ring-opening reaction with the epoxy group, and the resin system can be self-cured without adding traditional amine curing agents.

[0029] The inventors tried to use ceramic precursors such as polyborosilazane mixed with epoxy resin as a modified epoxy resin matrix. However, after many experiments, the prepared resin matrix was easy to separate into phases, basically had no mechanical properties, and the performance improvement effect in high temperature resistance was significantly lower than that of polysilazane. The reason may be that the special NH bond in polysilazane can undergo a ring-opening reaction with the epoxy group, which promotes the formation of a cured cross-linked network of the resin matrix.

[0030] In the present invention, polysilazane can be obtained commercially, preferably by the following preparation method:

[0031] Methyltrichlorosilane, methylvinyldichlorosilane and an organic solvent are added to a reaction device protected by inert gas, wherein the mass ratio of methyltrichlorosilane to methylvinyldichlorosilane is 3-1:1, ammonia is introduced into the container at a temperature of 0-5°C and stirred until the reactant becomes alkaline, and the temperature is raised to 60-80°C and stirred to obtain a crude product, and the solvent is removed by distillation to obtain polysilazane.

[0032] In the present invention, the mass ratio of epoxy resin to polysilazane is 2 to 5:1.

[0033] After research, the inventors found that when the mass ratio of epoxy resin to polysilazane is too high and higher than the maximum value of the above range, the high-temperature modification ability of polysilazane on epoxy resin is limited, and since the proportion of NH bonds in the epoxy resin system is too small, it does not have self-curing ability; when the mass ratio of epoxy resin to polysilazane is too low and lower than the minimum value of the above range, the mechanical properties of the resin matrix are significantly reduced.

[0034] The present invention also provides a precursor-modified high-temperature-resistant self-curing epoxy resin matrix, which is prepared by the above-mentioned precursor-modified high-temperature-resistant self-curing epoxy resin.

[0035] The self-curing system of the high temperature resistant self-curing epoxy resin matrix is: first react at 150-180° C. for 1-3 hours, then react at 180-210° C. for 1-3 hours, such as react at 170° C. for 2 hours, and then react at 190° C. for 2 hours.

[0036] The present invention also provides a precursor-modified high-temperature resistant self-curing epoxy resin matrix, which is used as a coating material and a composite material matrix resin.

[0037] Example

[0038] Example 1

[0039] A method for preparing a precursor-modified high-temperature resistant self-curing epoxy resin comprises the following steps:

[0040] The epoxy resin is bisphenol F diglycidyl ether epoxy resin, i.e. 830 epoxy resin. The preparation method of polysilazane comprises the following steps: adding 2 parts by mass of methyltrichlorosilane, 1 part by mass of methylvinyldichlorosilane and toluene solvent into a reaction device protected by inert gas, introducing ammonia gas into the container at 0°C and stirring until the reactant becomes alkaline, heating to 60°C and stirring to obtain a crude product, and distilling to remove the solvent to obtain polysilazane.

[0041] 5 parts (by mass) of 830 epoxy resin and 1 part (by mass) of polysilazane were placed in a beaker, a magnetic stirrer was placed, heated to 70°C, and stirred at 200 rpm for 0.5 hours. After stirring, the sample was poured into a mold preheated to 70°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature to obtain a precursor-modified high-temperature resistant epoxy resin 1.

[0042] Figure 1 The infrared spectra of the used 830 epoxy resin (#1) and the obtained precursor-modified high temperature resistant epoxy resin before curing (#2) and after curing (#3) are given. It can be seen that #2 has obvious absorption peaks of NH and Si-N belonging to polysilazane, which proves the introduction of polysilazane. The NH absorption peak disappears in #3 after curing, which proves that NH participates in the curing reaction.

[0043] Example 2

[0044] A method for preparing a precursor-modified high-temperature resistant self-curing epoxy resin comprises the following steps:

[0045] The epoxy resin is bisphenol F diglycidyl ether type epoxy resin, that is, 830 epoxy resin; the preparation method of polysilazane is consistent with that of Example 1.

[0046] 2 parts (mass parts) of 830 epoxy resin and 1 part (mass parts) of polysilazane were placed in a beaker, a magnetic stirrer was placed, heated to 70°C, and stirred at 300 rpm for 1 hour. After stirring, the sample was poured into a mold preheated to 70°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature to obtain a precursor-modified high-temperature resistant epoxy resin 2.

[0047] Example 3

[0048] A method for preparing a precursor-modified high-temperature resistant self-curing epoxy resin comprises the following steps:

[0049] The epoxy resin is 4,5-epoxycycloethane-1,2-dicarboxylic acid diglycidyl ester, namely TDE-85 epoxy resin; the preparation method of polysilazane is consistent with that of Example 1.

[0050] 5 parts (by mass) of TDE-85 epoxy resin and 1 part (by mass) of polysilazane were placed in a beaker, a magnetic stirrer was placed, heated to 80°C, and stirred at 200 rpm for 0.5 hours. After stirring, the sample was poured into a mold preheated to 80°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the procedure was completed, the sample was annealed to room temperature to obtain a precursor-modified high-temperature resistant epoxy resin 3. Samples such as Figure 2 As shown, there are no cracks or bubbles.

[0051] Example 4

[0052] A method for preparing a precursor-modified high-temperature resistant self-curing epoxy resin comprises the following steps:

[0053] The epoxy resin is 4,5-epoxycycloethane-1,2-dicarboxylic acid diglycidyl ester, namely TDE-85 epoxy resin; the preparation method of polysilazane is consistent with that of Example 1.

[0054] 2 parts (by mass) of TDE-85 epoxy resin and 1 part (by mass) of polysilazane were placed in a beaker, a magnetic stirrer was placed, heated to 80°C, and stirred at 300 rpm for 1 hour. After stirring, the sample was poured into a mold preheated to 80°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature to obtain a precursor-modified high-temperature resistant epoxy resin 4.

[0055] Comparative Example

[0056] Comparative Example 1

[0057] A method for preparing a precursor-modified epoxy resin comprises the following steps:

[0058] The epoxy resin is 830 epoxy resin; the preparation method of polysilazane is consistent with that in Example 1.

[0059] 1 part (mass) of 830 epoxy resin and 4 parts (mass) of polysilazane were placed in a beaker, a magnetic stirrer was placed, heated to 70°C, and stirred at 200 rpm for 0.5 hours. After stirring, the sample was poured into a mold preheated to 70°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature. A large number of cracks were distributed on the sample, such as cracking. Figure 3 .

[0060] Comparative Example 2

[0061] A method for preparing a precursor-modified epoxy resin comprises the following steps:

[0062] The epoxy resin is TDE-85 epoxy resin; the preparation method of polysilazane is consistent with that in Example 1.

[0063] 1 part (by mass) of TDE-85 epoxy resin and 9 parts (by mass) of polysilazane were placed in a beaker, a magnetic stirrer was placed, heated to 80°C, and stirred at 200 rpm for 0.5 hours. After stirring, the sample was poured into a mold preheated to 80°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature. The sample was foamed and mixed with a large number of bubbles, such as Figure 4 .

[0064] Comparative Example 3

[0065] A method for preparing a precursor-modified epoxy resin comprises the following steps:

[0066] The epoxy resin is bisphenol F diglycidyl ether type epoxy resin, namely 830 epoxy resin. The preparation method of polysilazane is consistent with that of Example 1.

[0067] 5 parts (by mass) of 830 epoxy resin and 1 part (by mass) of polycarbosilane were placed in a beaker, a magnetic stirrer was placed, heated to 70°C, and stirred at 200 rpm for 0.5 hours. After the stirring was completed, the beaker was clearly phase-separated, and the sample was poured into a mold preheated to 70°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature. The surface of the cast specimen obtained had bubbles, was whitish, was soft, and did not have mechanical properties.

[0068] Comparative Example 4

[0069] A method for preparing a precursor-modified epoxy resin comprises the following steps:

[0070] The epoxy resin is bisphenol F diglycidyl ether type epoxy resin, namely 830 epoxy resin. The preparation method of polysilazane is consistent with that of Example 1.

[0071] 5 parts (by mass) of 830 epoxy resin and 1 part (by mass) of polyborosilazane were placed in a beaker, a magnetic stirrer was placed, heated to 70°C, and stirred at 200 rpm for 0.5 hours. After stirring, the sample was poured into a mold preheated to 70°C and placed in a vacuum oven for degassing for 5 minutes. The resin was cured at 170°C for 2 hours and at 190°C for 2 hours. After the program was completed, the sample was annealed to room temperature, and it was found that the sample shrank severely and cracked into small pieces.

[0072] Performance Testing

[0073] (1) The above Examples 1 to 4 and Comparative Examples 3 to 4 were subjected to a thermal weight loss test. The specific method is as follows: a certain amount of sample was placed in a synchronous thermal analyzer balance, and the temperature was raised from room temperature to 900°C under an inert gas environment, and the heating rate was set to 5°C / min; the residual weight after 900°C was measured. The resins obtained from the above Examples 1 to 4 and Comparative Examples 3 to 4 were subjected to a mechanical property test. The results are shown in Table 1.

[0074] Table 1 Performance comparison of Examples 1 to 4 and Comparative Examples 3 to 4

[0075] Performance parameters / Example + Comparative example Example 1 Example 2 Example 3 Example 4 Residual weight / % 47.68 54.26 48.92 56.31 Tensile strength / MPa 33.6 30.3 45.5 30.3 Tensile modulus / GPa 4.59 3.79 5.35 3.91

[0076] The traditional resins 830 epoxy resin and TDE-85 used in the embodiments and comparative examples of the present invention were also subjected to thermal weight loss tests. At 900°C, their residual weights were only 3.27% and 4.66%, respectively. However, as can be seen from the data in Table 1, the residual weights of several embodiments provided by the present invention all exceeded 45%, indicating that the present invention effectively improves the high temperature resistance of the epoxy resin while ensuring the mechanical properties of the epoxy resin.

[0077] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0078] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A precursor-modified high temperature resistant self-curing epoxy resin matrix, characterized in that: The epoxy resin and polysilazane are mixed to obtain the epoxy resin, wherein the mass ratio of the epoxy resin to the polysilazane is 2 to 5:

1.

2. The precursor-modified high temperature resistant self-curing epoxy resin matrix according to claim 1, characterized in that: The polysilazane is obtained by the following preparation method: Methyltrichlorosilane, methylvinyldichlorosilane and an organic solvent are added to a reaction device protected by an inert gas, ammonia gas is introduced into the container at a temperature of 0 to 5° C. and stirred until the reactant becomes alkaline, and the temperature is raised to 60 to 80° C. and stirred to obtain a crude product, and the solvent is removed by distillation to obtain polysilazane.

3. The precursor-modified high temperature resistant self-curing epoxy resin matrix according to claim 2, characterized in that: The mass ratio of the methyltrichlorosilane to the methylvinyldichlorosilane is 3 to 1:

1.

4. A precursor-modified high temperature resistant self-curing epoxy resin matrix, characterized in that: The epoxy resin and polysilazane are mixed and cured to obtain the epoxy resin and polysilazane, wherein the mass ratio of the epoxy resin to the polysilazane is 2 to 5:

1.

5. The precursor-modified high temperature resistant self-curing epoxy resin matrix according to claim 4, characterized in that: The polysilazane is obtained by the following preparation method: Methyltrichlorosilane, methylvinyldichlorosilane and an organic solvent are added to a reaction device protected by an inert gas, ammonia gas is introduced into the container at a temperature of 0 to 5° C. and stirred until the reactant becomes alkaline, and the temperature is raised to 60 to 80° C. and stirred to obtain a crude product, and the solvent is removed by distillation to obtain polysilazane.

6. The precursor-modified high temperature resistant self-curing epoxy resin matrix according to claim 5, characterized in that: The mass ratio of the methyltrichlorosilane to the methylvinyldichlorosilane is 3 to 1:

1.

7. The precursor-modified high temperature resistant self-curing epoxy resin matrix according to claim 4, characterized in that: The self-curing system of the high temperature resistant self-curing epoxy resin matrix is: first react at 150-180° C. for 1-3 hours, and then react at 180-210° C. for 1-3 hours.

8. A method for preparing the precursor-modified high temperature resistant self-curing epoxy resin matrix according to claim 1, characterized in that: The steps include: Mix epoxy resin and polysilazane evenly at room temperature; The mixed system is reacted at 70-80° C. under stirring conditions for 0.5-2 hours to obtain a high temperature resistant self-curing epoxy resin.

9. A fiber-reinforced resin-based composite material, characterized in that: Fiber is used as reinforcement, and the high temperature resistant self-curing epoxy resin matrix modified by the precursor according to any one of claims 1 to 3 is used as the matrix resin of the composite material.

10. Use of the precursor-modified high-temperature resistant self-curing epoxy resin matrix according to any one of claims 1 to 3 as a coating material or a composite material matrix resin.

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