CN116444768A - High-efficiency damage self-repairing degradable double dynamic crosslinking Vitrimer resin - Google Patents

Abstract

The invention discloses a highly efficient damage self-repairing and degradable dual dynamic cross-linked Vitrimer resin, comprising the following molar parts of raw materials: E-51 type bisphenol A epoxy resin (DGEBA), 3,3'-dithiodipropionic acid (DTDPA), 2-methylhexahydrophthalic anhydride (MHHPA), triethanolamine (TEOA), wherein triethanolamine is the transesterification catalyst, 3,3'-dithiodipropionic acid and 2-methylhexahydrophthalic anhydride are Curing agent, the present invention introduces the transesterification catalyst triethanolamine into the traditional resin crosslinking network, and blends the curing agent DTDPA containing dynamic disulfide bonds with the traditional curing agent MHHPA to construct a dual dynamic based on transesterification and dynamic disulfide bonds. The cross-linked Vitrimer resin can effectively improve the shortcomings of traditional epoxy resins, such as poor dynamic properties and non-repairable and non-degradable damage, so that it can repair a certain degree of damage and prolong the service life of equipment. Non-destructive recycling of materials to reduce solid waste pollution.

Description

Efficient damage self-healing degradable dual dynamic cross-linked Vitrimer resin

technical field

The invention relates to the technical field of resins, in particular to a highly efficient damage self-repairing and degradable double dynamic cross-linked Vitrimer resin.

Background technique

Epoxy resin materials are an important class of thermosetting resins, which have good arc resistance, heat resistance, low corrosion, electrical insulation, etc. Epoxy resins have excellent physical, mechanical and electrical insulation properties, and adhesion to various materials. The connection performance and the flexibility of its use process are not available in other thermosetting plastics, so it can be made into coatings, composite materials, casting materials, adhesives, molding materials and injection molding materials, and is widely used in various fields of the national economy. In recent years, epoxy resin materials have been widely used in transmission lines and power equipment. In the preparation of epoxy resin, epoxy resin curing agents are often used for curing. The curing process is simple and the electrical insulation performance is excellent;

However, the resin crosslinking network cured by the epoxy resin curing agent 2-methylhexahydrophthalic anhydride (MHHPA) is permanently crosslinked and irreversible, and the damaged resin cannot be recycled and reprocessed. Cross-linked Vitrimer resin.

Contents of the invention

The present invention provides a highly efficient damage self-repairing and degradable dual dynamic cross-linked Vitrimer resin, which can effectively solve the problem of permanent cross-linking of the resin cross-linked network after the epoxy resin curing agent 2-methylhexahydrophthalic anhydride (MHHPA) is cured in the above-mentioned background technology. The connection is irreversible, and the damaged resin cannot be recycled and reprocessed.

In order to achieve the above object, the present invention provides the following technical solutions: a highly efficient damage self-repairing degradable dual dynamic cross-linked Vitrimer resin, comprising the following molar parts of raw materials:

E-51 bisphenol A epoxy resin (DGEBA);

3,3'-dithiodipropionic acid (DTDPA);

2-Methylhexahydrophthalic anhydride (MHHPA);

Triethanolamine (TEOA);

Wherein, triethanolamine is a transesterification catalyst;

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

According to the above technical solution, the proportion of 3,3'-dithiodipropionic acid in the curing agent is 10-50%.

A method for preparing a highly efficient damage self-repairing degradable dual dynamic cross-linked Vitrimer resin, comprising the following steps:

S1. Weigh the corresponding proportion of E-51 resin and add it to the container, then weigh a certain proportion of curing agent DTDPA and add it to the container, and completely dissolve the DTDPA at 150°C;

S2. After cooling to 80°C, add a certain proportion of the curing agent MHHPA that has been weighed, and finally add the transesterification catalyst TEOA with a mole fraction of epoxy groups of 5%;

S3. Maintain a constant temperature of 80°C in a water bath and stir for 6-8 minutes to prepare a resin prepolymer glue;

S4. Carry out vacuum defoaming treatment for 15 minutes in a vacuum drying oven with a temperature environment of 80° C.;

S5. Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then perform constant temperature and vacuum defoaming treatment for 15 minutes;

S6. Curing at 110° C. for 2 hours, 130° C. for 2 hours, and 150° C. for 3 hours, cooling naturally, and demoulding.

Compared with prior art, the beneficial effect of the present invention:

1. The present invention mixes the carboxylic acid curing agent DTDPA containing dynamic disulfide bonds with the traditional acid anhydride curing agent MHHPA, and prepares and synthesizes a kind of excellent dynamic characteristics, high-efficiency damage self-repairing characteristics, and Degradation of dual dynamically cross-linked Vitrimer resins.

2. The preparation method of Vitrimer resin provided by the present invention can flexibly adjust the proportioning ratio of curing agent DTDPA and MHHPA according to the requirements of different crosslinked network structures of the resin, and construct a novel dual dynamic crosslinked Vitrimer resin with different dynamic crosslinked structures, Applied to different scenarios.

3. The damage repair efficiency of the double dynamic crosslinked Vitrimer resin cured product of the present invention is better than that of a single transesterified resin system. When the proportion of DTDPA in the curing agent increases from 0% to 50%, the prepared Vitrimer resin The surface scratch repair rate of the cured product has increased from 70% to 93%. In addition, the prepared resin system can also realize the repair of various types of damage such as fracture bonding and electric tree damage repair.

4. With the increase of the DTDPA content of the resin of the present invention, the degradation rate of the cured resin is greatly accelerated. When the proportion of DTDPA is 50%, the resin matrix can be completely degraded under the airtight condition of 190°C in the ethylene glycol solution. High-value copper windings in a resin matrix are recycled non-destructively.

In summary, by introducing the transesterification catalyst triethanolamine into the traditional resin crosslinking network, and blending the dynamic disulfide bond-containing curing agent DTDPA with the traditional curing agent MHHPA, a dual resin based on transesterification and dynamic disulfide bonds was constructed. Dynamically crosslinked Vitrimer resin, with the increase of DTDPA proportion, the stress relaxation time constant of the resin system is significantly reduced, indicating that the dynamic characteristics of the resin system are significantly enhanced, and the surface scratch repair rate of the prepared Vitrimer resin cured product is improved, and the resin system Under the condition of ethylene glycol solution, the degradation speed is obviously accelerated, and the resin matrix can be completely degraded, which can effectively improve the shortcomings of traditional epoxy resins, such as poor dynamic properties, irreparable damage and non-degradable damage, so that it can repair a certain degree of damage and prolong the use of equipment At the same time, it is convenient for later decommissioning and recycling, so as to realize the non-destructive recycling of high-value materials and reduce solid waste pollution.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.

In the attached picture:

Fig. 1 is a schematic diagram of the chemical reaction principle of Vitrimer resin of the present invention;

Fig. 2 is the schematic diagram of the preparation process of dual dynamic cross-linked Vitrimer resin of the present invention;

Fig. 3 is the Vitrimer resin stress relaxation diagram of different DTDPA contents of the present invention;

Fig. 4 is the relationship figure of Vitrimer resin surface scratch repair rate of the present invention and different DTDPA contents;

Fig. 5 is the relationship diagram of the degradation rate of the resin system of the present invention and the proportion of DTDPA content in ethylene glycol;

Fig. 6 is an experiment diagram of a simulated dry-type transformer pouring winding degradation recovery experiment of the present invention.

Detailed ways

The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Example 1:

As shown in Figure 1-2, the present invention provides a technical solution, a highly efficient damage self-repairing degradable dual dynamic cross-linked Vitrimer resin, including the following molar parts of raw materials:

E-51 bisphenol A epoxy resin (DGEBA);

3,3'-dithiodipropionic acid (DTDPA);

2-Methylhexahydrophthalic anhydride (MHHPA);

Triethanolamine (TEOA);

Among them, triethanolamine is a transesterification catalyst, and 3,3'-dithiodipropionic acid and 2-methylhexahydrophthalic anhydride are curing agents.

It can be seen from Fig. 1 that after introducing these two reversible dynamic structures into the resin crosslinking network, the reversible network topology makes the macroscopic resin have dynamic properties.

The method for preparing the above-mentioned highly efficient damage self-repairing degradable dual dynamic cross-linked Vitrimer resin is as follows:

Weigh a certain amount of E-51 resin, add it to the container, weigh DTDPA with a curing agent mole ratio of 10%, add it to the container, and completely dissolve the DTDPA at 150°C;

After cooling to 80°C, add a weighed 90% curing agent MHHPA, and finally add a transesterification catalyst TEOA with a molar fraction of epoxy groups of 5%;

Keep a constant temperature of 80°C in a water bath and stir for 6-8 minutes to prepare the resin prepolymer glue;

Carry out vacuum defoaming treatment for 15 minutes in a vacuum drying oven with a temperature environment of 80°C;

Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then conduct constant temperature and vacuum defoaming treatment for 15 minutes;

Curing at 110°C for 2 hours, 130°C for 2 hours, 150°C for 3 hours, cooling naturally, and demoulding, then you can get a degradable double dynamic covalent bond cross-linked composite with certain damage repair ability. Cured product of Vitrimer resin.

Example 2: Weigh a certain amount of E-51 resin, add it to a container, weigh DTDPA with a curing agent mole ratio of 30%, add it to the container, and completely dissolve DTDPA at 150°C;

After cooling to 80°C, add a weighed 70% curing agent MHHPA, and finally add a transesterification catalyst TEOA with a molar fraction of epoxy groups of 5%;

Keep a constant temperature of 80°C in a water bath and stir for 6-8 minutes to prepare the resin prepolymer glue;

Carry out vacuum defoaming treatment for 15 minutes in a vacuum drying oven with a temperature environment of 80°C;

Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then conduct constant temperature and vacuum defoaming treatment for 15 minutes;

Curing at 110°C for 2 hours, 130°C for 2 hours, 150°C for 3 hours, cooling naturally, and demoulding, then you can get a degradable double dynamic covalent bond cross-linked composite with certain damage repair ability. Cured product of Vitrimer resin.

Example 3: Weigh a certain amount of E-51 resin, add it to a container, weigh DTDPA with a curing agent mole ratio of 50%, add it to the container, and completely dissolve DTDPA at 150°C;

After cooling to 80°C, add a weighed 50% curing agent MHHPA, and finally add a transesterification catalyst TEOA with a mole fraction of epoxy groups of 5%;

Keep a constant temperature of 80°C in a water bath and stir for 6-8 minutes to prepare the resin prepolymer glue;

Carry out vacuum defoaming treatment for 15 minutes in a vacuum drying oven with a temperature environment of 80°C;

Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then conduct constant temperature and vacuum defoaming treatment for 15 minutes;

Curing at 110°C for 2 hours, 130°C for 2 hours, 150°C for 3 hours, cooling naturally, and demoulding, then you can get a degradable double dynamic covalent bond cross-linked composite with certain damage repair ability. Cured product of Vitrimer resin.

Comparative example 1: Weigh the corresponding proportion of E-51 resin, add it to the container, then weigh the curing agent MHHPA with a mass fraction of 80wt%, and add it to the container;

Finally add the transesterification catalyst TEOA of epoxy group molar ratio fraction 5%;

Keep a constant temperature of 80°C in a water bath and stir for 6-8 minutes to prepare the resin glue;

Carry out vacuum defoaming treatment for 15 minutes in a vacuum drying oven with a temperature environment of 80°C;

Slowly pour the mixed solution into a preheated stainless steel mold coated with a release agent, and then conduct constant temperature and vacuum defoaming treatment for 15 minutes;

Cured at 110°C for 2 hours, 130°C for 2 hours, 150°C for 3 hours, cooled naturally, and demolded to obtain a single transesterified Vitrimer resin cured product.

According to the content of comparative example 1 and embodiment 1-3, make following curing agent ratio table:

The resin prepared by above-mentioned comparative example 1 and embodiment 1-3 is tested as follows:

1. Stress relaxation performance test: Tensile loading is carried out under the condition of 180 ℃, and then as time goes by, while keeping the total deformation at 1%, the decrease value of stress over time is measured, and the stress is normalized and drawn. Stress relaxation curves were tested using the tensile mode of the stress relaxation test of a dynamic mechanical analyzer (TA DMA850).

2. Surface scratch damage repair test: Use a scalpel to scratch the surface of the cured sample at the same depth and width, observe the surface scratches with an optical microscope, record the original appearance and width of the scratches, and place the sample on the Put it in a drying oven at 190°C for 5 minutes, take it out, and use an optical microscope to observe the relevant data after the surface scratches are repaired again.

3. Degradation and recovery test: put the copper wire in the pouring mold to simulate the winding of dry-type transformer, use the above resin preparation and pouring process to prepare the simulated dry-type transformer device, place the simulated device in ethylene glycol solution, and keep it under airtight conditions at 190°C Carry out degradation and recovery experiments, record the proportion of resin remaining mass as a function of degradation time, and use scanning electron microscopy (SEM, JSM-IT500, JEOR) to observe the details of the appearance of the winding surface before and after recovery.

The stress relaxation performance test results are shown in Figure 3. The stress relaxation test data of the Vitrimer resin system with different DTDPA content in the curing agent at 180°C shows that the stress relaxation time of the resin system increases with the increase of the DTDPA content. The constant is significantly reduced, indicating that the dynamic properties of the resin system are significantly enhanced. When the molar ratio of DTDPA curing agent is 50%, the stress relaxation time of the cured product is only 489s.

The surface scratch damage repair test results are shown in Figure 4. The relationship between the surface scratch damage repair rate of Vitrimer resin with different DTDPA content in the curing agent can be seen. 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 was increased from 70% to 93%.

When the content of DTDPA is 50%, the damage repair efficiency of surface scratches is as high as 93% within 5 minutes, and the prepared dual dynamic cross-linked Vitrimer resin still maintains good comprehensive electrical properties;

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

The results of the degradation recovery test are shown in Figure 5. The relationship between the different proportions of DTDPA in the Vitrimer resin system and the degradation rate in ethylene glycol solution can be seen. The degradation speed is obviously accelerated under the condition of airtight high temperature in the alcohol solution. When the molar content of DTDPA curing agent is 50%, the resin matrix can be completely degraded within 5.5 hours;

As shown in Figure 6, different DTDPA proportions simulated the degradation and recycling experiment of dry-type transformer pouring windings. It can be seen that with the increase of the proportion of DTDPA containing dynamic disulfide bonds, the degradability of the resin is significantly enhanced. Simulated dry-type The high-value copper windings inside the resin matrix can be recycled non-destructively after the transformer casting device is kept at 190°C for 6 hours. Compared with the traditional incineration and landfill, this recycling method greatly reduces solid waste pollution.

Finally, it should be noted that: the above is only a preferred example of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it can still The technical solutions recorded in the foregoing embodiments are modified, or some of the technical features are equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. The high-efficiency damage self-repairing degradable double dynamic crosslinking Vitrer resin is characterized in that: comprises the following raw materials in parts by mole:

e-51 bisphenol A epoxy resin (DGEBA);

3,3' -dithiodipropionic acid (DTDPA);

2-methyl hexahydrophthalic anhydride (MHHPA);

triethanolamine (TEOA);

wherein, triethanolamine is an ester exchange catalyst;

3,3' -dithiodipropionic acid and 2-methyl hexahydrophthalic anhydride are used as curing agents.

2. The high efficiency damage self-repairing degradable double dynamic cross-linked Vitrimer resin of claim 1, wherein the 3,3' -dithiodipropionic acid in the curing agent is 10-50%.

3. The method for preparing the high-efficiency damage self-repairing degradable double dynamic crosslinking Vitrimer resin according to any one of claims 1 to 2, which comprises the following steps:

s1, weighing a proportion of E-51 resin, adding the weighed proportion of curing agent DTDPA into a container, and completely dissolving the DTDPA at 150 ℃;

s2, cooling to 80 ℃, adding a weighed proportion of curing agent MHHPA, and finally adding an ester exchange catalyst TEOA with the mole fraction of epoxy groups of 5%;

s3, stirring for 6-8 min in a water bath kettle at the constant temperature of 80 ℃ to prepare resin prepolymer glue solution;

s4, performing vacuum defoaming treatment for 15min in a vacuum drying oven with the temperature environment of 80 ℃;

s5, slowly pouring the mixed solution into a stainless steel die which is preheated and coated with a release agent, and then carrying out constant-temperature vacuum defoaming treatment for 15min;

s6, solidifying for 2 hours at the temperature of 110 ℃, solidifying for 2 hours at the temperature of 130 ℃, solidifying for 3 hours at the temperature of 150 ℃, naturally cooling and demoulding.