Highly efficient damage self-healing degradable dual-dynamic cross-linked vitrimer resin

Abstract

The application discloses a high-efficiency damage self-repairing degradable double-dynamic crosslinking Vitrimer resin, which comprises the following raw materials in terms of mole: an E-51 type bisphenol A epoxy resin (DGEBA), 3,3'-dithiodipropionic acid (DTDPA), 2-methylhexahydrophthalic anhydride (MHHPA) and triethanolamine (TEOA), wherein the triethanolamine is an ester exchange catalyst, the 3,3'-dithiodipropionic acid and the 2-methylhexahydrophthalic anhydride are curing agents. The application introduces the ester exchange catalyst triethanolamine into a traditional resin crosslinking network, blends the curing agent DTDPA containing a dynamic disulfide bond with the traditional curing agent MHHPA, constructs the double-dynamic crosslinking Vitrimer resin based on ester exchange and dynamic disulfide bond, effectively improves the shortcomings that the traditional epoxy resin has poor dynamic characteristics and is not repairable and degradable, enables the epoxy resin to repair a certain degree of damage, prolongs the service life of equipment, is convenient for post-service recycling and treatment, realizes lossless recycling of high-value materials, and reduces solid waste pollution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resin, in particular to a high-efficiency damage self-repairing degradable dual dynamic crosslinking Vitrimer resin. BACKGROUND

[0002] Epoxy resin material is an important thermosetting resin, which has good arc resistance, heat resistance, low corrosion resistance, electrical insulation and other properties. The excellent physical and mechanical and electrical insulation properties of epoxy resin, the bonding properties with various materials, and the flexibility of its use process are not possessed by other thermosetting plastics. Therefore, it can be made into coatings, composites, casting materials, adhesives, molding materials and injection molding materials, and is widely used in various fields of national economy. In recent years, epoxy resin materials have been widely used in power transmission lines and electrical equipment. Epoxy resin curing agent is often used in the preparation of epoxy resin for curing. The curing process is simple, and the electrical insulation performance is excellent.

[0003] However, the crosslinked network of the resin cured by the epoxy resin curing agent 2-methylhexahydrophthalic anhydride (MHHPA) is permanently crosslinked and irreversible. The damaged resin cannot be recycled and reprocessed. Therefore, it is necessary to prepare a high-efficiency damage self-repairing degradable dual dynamic crosslinking Vitrimer resin. SUMMARY

[0004] The present application provides a high-efficiency damage self-repairing degradable dual dynamic crosslinking Vitrimer resin, which can effectively solve the problem of permanent crosslinking and irreversible crosslinked network of the resin cured by the epoxy resin curing agent 2-methylhexahydrophthalic anhydride (MHHPA) in the background art.

[0005] To achieve the above purpose, the present application provides the following technical scheme: a high-efficiency damage self-repairing degradable dual dynamic crosslinking Vitrimer resin, comprising the following molar parts of raw materials:

[0006] E-51 type bisphenol A epoxy resin (DGEBA);

[0007] 3,3'-dithiodipropionic acid (DTDPA);

[0008] 2-methylhexahydrophthalic anhydride (MHHPA);

[0009] triethanolamine (TEOA);

[0010] Among them, triethanolamine is an ester exchange catalyst;

[0011] 3,3'-dithiodipropionic acid and 2-methylhexahydrophthalic anhydride are curing agents.

[0012] According to the technical scheme, the proportion of 3,3'-dithiodipropionic acid in the curing agent is 10-50%.

[0013] The preparation method of the high-efficiency damage self-repairable degradable dual-dynamic crosslinking Vitrimer resin comprises the following steps:

[0014] S1, the corresponding proportion of E-51 resin is weighed and added to the container, and a certain proportion of curing agent DTDPA is weighed and added to the container, and the DTDPA is completely dissolved at 150 DEG C.

[0015] S2, after cooling to 80 DEG C, a certain proportion of curing agent MHHPA is weighed and added, and finally an ester exchange catalyst TEOA with a molar fraction of 5% of epoxy groups is added;

[0016] S3, keep constant temperature 80 DEG C in water bath pot stirring 6-8 min, prepare resin prepolymer glue liquid;

[0017] S4, vacuum degassing treatment is carried out in the vacuum drying box with temperature environment of 80 DEG C for 15 min;

[0018] S5, slowly pour the mixed solution into the preheated stainless steel mold coated with release agent, and then constant temperature vacuum degassing treatment for 15 min;

[0019] S6, curing at 110 DEG C for 2h, curing at 130 DEG C for 2h, curing at 150 DEG C for 3h, natural cooling, demolding.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] 1, the carboxylic acid curing agent DTDPA containing dynamic disulfide bond is mixed with the traditional acid anhydride curing agent MHHPA, and a dual-dynamic crosslinking Vitrimer resin with excellent dynamic characteristics, high-efficiency damage self-repairing characteristics and degradability is prepared under the catalysis of ester exchange catalyst TEOA.

[0022] 2, the preparation method of the Vitrimer resin provided by the present application can flexibly adjust the ratio of curing agents DTDPA and MHHPA according to the demand of different crosslinking network structure of the resin, and construct a new dual-dynamic crosslinking Vitrimer resin with different dynamic crosslinking structure, which is applied to different scene requirements.

[0023] 3、The damage repair efficiency of the double dynamic crosslinking Vitrimer resin cured product of the application is better than that of a single ester exchange resin system, when the DTDPA content in the curing agent increases from 0% to 50%, the surface scratch repair rate of the prepared Vitrimer resin cured product increases from 70% to 93%, in addition, the prepared resin system can also realize the repair of various types of damage forms such as fracture bonding and electrical tree damage repair.

[0024] 4、With the increase of the DTDPA content of the resin, the degradation rate of the resin cured product is greatly accelerated, when the DTDPA content is 50%, the resin matrix can be completely degraded in a 190 DEG C closed condition in ethylene glycol solution, and the high-value copper winding in the resin matrix can be recovered without damage.

[0025] In summary, by introducing the ester exchange catalyst triethanolamine into the traditional resin crosslinking network, and by blending the dynamic disulfide bond-containing curing agent DTDPA with the traditional curing agent MHHPA, a double dynamic crosslinking Vitrimer resin based on ester exchange and dynamic disulfide bond is constructed, with the increase of the DTDPA content, the stress relaxation time constant of the resin system is obviously reduced, indicating that the dynamic characteristics of the resin system are obviously enhanced, the surface scratch repair rate of the prepared Vitrimer resin cured product is improved, the degradation rate of the resin system in ethylene glycol solution is obviously accelerated, the resin matrix can be completely degraded, the disadvantages of poor dynamic characteristics of traditional epoxy resin, non-repairable and non-degradable damage are effectively improved, so that it can repair a certain degree of damage, prolong the service life of the equipment, at the same time, it is convenient for the later retirement and recycling treatment, realizes the non-damage recovery of high-value materials, and reduces the solid waste pollution. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, together with the embodiments of the application, to explain the application, and do not constitute a limitation on the application.

[0027] In the drawings:

[0028] Figure 1 is a schematic diagram of the chemical reaction principle of the Vitrimer resin of the application;

[0029] Figure 2 is a schematic diagram of the preparation process of the double dynamic crosslinking Vitrimer resin of the application;

[0030] Figure 3 is a stress relaxation relationship diagram of the Vitrimer resin with different DTDPA contents of the application;

[0031] Figure 4 is a relationship diagram of the surface scratch repair rate of the Vitrimer resin of the application and different DTDPA contents.

[0032] Figure 5 is a graph of the relationship between the degradation rate of the resin system in ethylene glycol and the content ratio of DTDPA of the present application;

[0033] Figure 6 is a degradation and recovery experiment graph of the simulated dry-type transformer pouring winding of the present application. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0035] Example 1:

[0036] As shown in Figures 1-2 , the present application provides a technical solution, an efficient damage self-repairing degradable double dynamic crosslinking Vitrimer resin, which comprises the following molar parts of raw materials:

[0037] E-51 type bisphenol A epoxy resin (DGEBA);

[0038] 3,3'-dithiodipropionic acid (DTDPA);

[0039] 2-methylhexahydrophthalic anhydride (MHHPA);

[0040] triethanolamine (TEOA);

[0041] Among them, triethanolamine is an ester exchange catalyst, and 3,3'-dithiodipropionic acid and 2-methylhexahydrophthalic anhydride are curing agents.

[0042] As can be seen from Figure 1 , after introducing the two reversible dynamic structures into the resin crosslinking network, the reversible network topology makes the macroscopic resin have dynamic characteristics.

[0043] The method for preparing the above-mentioned efficient damage self-repairing degradable double dynamic crosslinking Vitrimer resin is as follows:

[0044] A certain amount of E-51 resin is weighed and added to a container, and a curing agent DTDPA with a molar content of 10% is weighed and added to the container. The DTDPA is completely dissolved at 150°C;

[0045] After cooling to 80°C, the weighed 90% proportion of the curing agent MHHPA is added, and finally the ester exchange catalyst TEOA with a molar fraction of 5% of the epoxy group is added;

[0046] Keep the water bath pot at a constant temperature of 80°C and stir for 6-8 min to prepare the resin prepolymer glue solution;

[0047] Vacuum degassing treatment for 15 min in a vacuum drying oven with a temperature environment of 80℃;

[0048] Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then vacuum degassing treatment for 15 min at constant temperature;

[0049] Curing at a temperature of 110℃ for 2h, at a temperature of 130℃ for 2h, at a temperature of 150℃ for 3h, natural cooling, demolding, then a certain damage repair ability, degradable double dynamic covalent bond crosslinked Vitrimer resin cured product is obtained.

[0050] Example 2: A certain amount of E-51 resin is weighed and added to the container, and the curing agent DTDPA with a molar ratio of 30% is weighed and added to the container. The DTDPA is completely dissolved at 150℃;

[0051] After cooling to 80℃, add the weighed curing agent MHHPA with a proportion of 70%, and finally add the ester exchange catalyst TEOA with a molar fraction of 5% of epoxy groups;

[0052] Stir in a water bath at 80℃ for 6-8 min to prepare a resin prepolymer glue solution;

[0053] Vacuum degassing treatment for 15 min in a vacuum drying oven with a temperature environment of 80℃;

[0054] Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then vacuum degassing treatment for 15 min at constant temperature;

[0055] Curing at a temperature of 110℃ for 2h, at a temperature of 130℃ for 2h, at a temperature of 150℃ for 3h, natural cooling, demolding, then a certain damage repair ability, degradable double dynamic covalent bond crosslinked Vitrimer resin cured product is obtained.

[0056] Example 3: A certain amount of E-51 resin is weighed and added to the container, and the curing agent DTDPA with a molar ratio of 50% is weighed and added to the container. The DTDPA is completely dissolved at 150℃;

[0057] After cooling to 80℃, add the weighed curing agent MHHPA with a proportion of 50%, and finally add the ester exchange catalyst TEOA with a molar fraction of 5% of epoxy groups;

[0058] Stir in a water bath at 80℃ for 6-8 min to prepare a resin prepolymer glue solution;

[0059] Vacuum degassing treatment for 15 min in a vacuum drying oven with a temperature environment of 80℃;

[0060] The mixed solution is slowly poured into a preheated stainless steel mold coated with a release agent, and then vacuum degassing treatment is performed at a constant temperature for 15 min.

[0061] Curing at a temperature of 110°C for 2h, 130°C for 2h, 150°C for 3h, natural cooling, demolding, then a Vitrimer resin cured product with certain damage repair ability and degradable double dynamic covalent bond crosslinking is obtained.

[0062] Comparative Example 1: The E-51 resin in the corresponding proportion is weighed and added to the container, and then the curing agent MHHPA with a mass fraction of 80wt% is weighed and added to the container.

[0063] Finally, an ester exchange catalyst TEOA with a mole fraction of 5% of the epoxy group is added.

[0064] Stir in a water bath at 80°C for 6-8 min to prepare the resin glue solution.

[0065] Vacuum degassing treatment is performed in a vacuum drying oven at a temperature of 80°C for 15 min.

[0066] The mixed solution is slowly poured into a preheated stainless steel mold coated with a release agent, and then vacuum degassing treatment is performed at a constant temperature for 15 min.

[0067] Curing at a temperature of 110°C for 2h, 130°C for 2h, 150°C for 3h, natural cooling, demolding, then a Vitrimer resin cured product with certain damage repair ability and degradable double dynamic covalent bond crosslinking is obtained.

[0068] According to the contents of Comparative Example 1 and Examples 1-3, the following curing agent proportion table is prepared:

[0069]

[0070] The resins prepared in the above Comparative Example 1 and Examples 1-3 are tested as follows:

[0071] 1. Stress relaxation performance test: Tensile loading is performed at 180°C, and then the stress reduction value with time is measured while keeping the total deformation unchanged at 1%, and the stress relaxation curve is drawn after normalization of the stress. The related test is performed using the tensile mode of dynamic mechanical analyzer (TA DMA850).

[0072] 2. Surface scratch damage repair test: A scalpel is used to make surface scratches of the same depth and width on the surface of the cured product sample, and an optical microscope is used to observe the surface scratches and record the original appearance and width of the scratches. The sample is placed in a 190°C drying oven for 5 min, and then the surface scratch repair data is observed again using an optical microscope.

[0073] 3. Degradation recycling test: copper wires were placed in a casting mold to simulate the winding of a dry-type transformer. The simulated dry-type transformer device was prepared using the above resin preparation and casting process, and then placed in a glycol solution. Degradation recycling experiments were carried out under 190°C closed conditions. The remaining mass fraction of the resin was recorded as a function of degradation time. The surface morphology of the winding before and after recycling was observed using a scanning electron microscope (SEM, JSM-IT500, JEOR).

[0074] The stress relaxation performance test results are shown in Figure 3 As shown in the stress relaxation experimental data of the Vitrimer resin system with different DTDPA content in the curing agent at 180°C, the stress relaxation time constant of the resin system decreased significantly with the increase of the DTDPA content, indicating that the dynamic characteristics of the resin system were significantly enhanced. When the molar content of the DTDPA curing agent was 50%, the stress relaxation time of the cured product was only 489s.

[0075] The surface scratch damage repair test results are shown in Figure 4 As shown in the relationship between the surface scratch damage repair rate of the Vitrimer resin with different DTDPA content in the curing agent, when the DTDPA content in the curing agent increased from 0% to 50%, the surface scratch repair rate of the prepared Vitrimer resin cured product increased from 70% to 93%.

[0076] When the DTDPA content was 50%, the surface scratch 5min damage repair efficiency was as high as 93%, and the prepared dual dynamic cross-linked Vitrimer resin still maintained good comprehensive electrical performance.

[0077] When the DTDPA content was 50%, the breakdown voltage was 37.82kV / mm, the leakage current was 38.04μA, and the dielectric loss tangent was 0.35%, which met the basic requirements of electrical materials.

[0078] The degradation recycling test results are shown in Figure 5 As shown in the relationship between the degradation rate of the Vitrimer resin system with different DTDPA content in the glycol solution, the degradation rate of the resin system in the glycol solution under closed high temperature conditions increased significantly with the increase of the DTDPA content in the curing agent. When the molar content of the DTDPA curing agent was 50%, the resin matrix could be completely degraded in 5.5h.

[0079] As shown in Figure 6As shown, the degradation and recycling experiment of the simulated dry-type transformer pouring winding with different DTDPA content ratio can be seen that with the increase of the content ratio of DTDPA with dynamic disulfide bond, the degradable performance of the resin is significantly enhanced, and the high-value copper winding in the resin matrix can be recycled without damage after 6h at 190℃. Compared with the traditional incineration landfill, this recycling method greatly reduces the solid waste pollution.

[0080] Finally, it should be pointed out that: the above only for the preferred examples of the present application, and is not intended to limit the present application, although the foregoing examples of the present application are described in detail, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement of the technical solutions recorded in the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A highly efficient, self-healing, biodegradable, dual-dynamically crosslinked Vitrimer resin, characterized by: Raw materials including the following molar amounts: E-51 type bisphenol A epoxy resin (DGEBA); 3,3'-Dithiodipropionic acid (DTDPA); 2-Methylhexahydrophthalic anhydride (MHHPA); Triethanolamine (TEOA); Triethanolamine is used as a transesterification catalyst. 3,3'-Dithiodipropionic acid and 2-methylhexahydrophthalic anhydride are used as curing agents; The curing agent contains 10-50% 3,3'-dithiodipropionic acid.

2. The method for preparing the highly efficient, self-healing, biodegradable, dual-dynamically crosslinked Vitrimer resin according to claim 1, characterized in that, Includes the following steps: S1. Weigh out the proportion of E-51 resin and add it to the container, then weigh out the proportion of curing agent DTDPA and add it to the container. Dissolve the DTDPA completely at 150°C. S2. After cooling to 80°C, add the weighed curing agent MHHPA, and finally add the transesterification catalyst TEOA with a molar fraction of 5% of epoxy groups. S3. Stir in a water bath at a constant temperature of 80℃ for 6-8 minutes to obtain the resin prepolymer solution. S4. Perform vacuum degassing treatment in a vacuum drying oven at a temperature of 80℃ for 15 minutes; S5. Slowly pour the mixture into a preheated stainless steel mold coated with release agent, and then perform constant temperature vacuum degassing treatment for 15 minutes. S6. Cure at 110℃ for 2 hours, at 130℃ for 2 hours, and at 150℃ for 3 hours. Allow to cool naturally before demolding.

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