High-temperature-resistant and corrosion-resistant epoxy sealant as well as preparation method and application thereof

Abstract

The invention relates to the field of battery packaging materials, and discloses a high-temperature-resistant and corrosion-resistant epoxy sealant as well as a preparation method and application thereof. The epoxy sealant comprises 40-50 wt% of a polythiol curing agent, 40-50 wt% of epoxy resin, 1-5 wt% of a curing accelerator and 1-5 wt% of a diluent, the polythiol curing agent is colorless transparent liquid formed by mixing and reacting pentaerythritol tetra-3-mercaptopropionate, trityl glycidyl ether and triethylamine. According to the epoxy sealant, a trityl rigid group is introduced, the steric hindrance effect of the trityl rigid group and a thiol group have a synergistic effect, a high-crosslinking-density network is formed, the ring-opening reaction activation energy is reduced, then the gelation time is shortened, the epoxy sealant has the high thermal weight loss temperature, hydrophobic group benzene rings block water molecule permeation, and the medium resistance is good; the epoxy sealant has high reliability and good bonding performance, is easy to operate, and can be used as a sealant material for packaging photovoltaic cell devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery packaging materials, in particular to a high-temperature-resistant and corrosion-resistant epoxy sealant, a preparation method and application thereof. BACKGROUND

[0002] As a core encapsulation material based on epoxy resin composition, epoxy sealant has become the core material in the field of electronic components, photovoltaic components and semiconductor chip packaging due to its excellent bonding strength, dielectric properties and chemical stability. In the field of photovoltaic cells, epoxy sealant plays an insulating protective role for the battery sheet and the wire, and at the same time prevents the corrosion of moisture and corrosive medium to the electrode material, directly affecting the long-term reliability and energy conversion efficiency of the device. With the rapid development of clean energy technology, especially the rise of new photovoltaic devices such as perovskite cells, the packaging material faces more stringent performance requirements: on the one hand, photovoltaic devices need to operate stably in extreme environments such as high temperature (> 85℃), high humidity (> 85% RH), strong ultraviolet radiation, etc.; on the other hand, halogen ions (such as I-, Br - ) and metal electrodes (such as silver, aluminum) in perovskite cells are extremely sensitive to corrosion, requiring sealants to have excellent barrier properties.

[0003] Traditional epoxy sealant systems usually use bisphenol A type epoxy resin combined with polythiol curing agent, supplemented with diluents, accelerators and other additives. Although such systems have basic protection functions, they have problems such as long gel time, poor high-temperature resistance and corrosion resistance in actual application. On the one hand, the low reactivity of the thiol group in the traditional polythiol curing agent, especially in low-temperature or high-humidity environments, increases the ring-opening reaction energy barrier, resulting in a sharp decrease in crosslinking rate and long gel time; on the other hand, the bisphenol A type epoxy resin contains flexible segments such as propyl and ether bonds, resulting in poor heat resistance. In addition, the traditional epoxy resin material contains hydrophilic groups such as residual hydroxyl (-OH) and ether bond (-O-), which form hydrogen bonds with water molecules to cause swelling, resulting in problems such as delamination, ion migration and efficiency decay after battery packaging.

[0004] To solve the above problems, the present technical solution introduces a triphenylmethyl rigid group into the polythiol curing agent through molecular structure innovation design, breaking through the traditional technical path of poor heat and moisture resistance, poor stability and low industrial adaptability, and providing a high-reliability packaging solution for new-generation photovoltaic devices such as perovskite cells. SUMMARY

[0005] The present application aims to overcome the problems of long gel time and poor high-temperature resistance and corrosion resistance of the existing epoxy sealant, and provides an epoxy sealant, a preparation method and application thereof. The technical scheme adopts thiol-Michael addition reaction to prepare a mercaptan curing agent, improves the conversion rate, and at the same time, introduces a triphenylmethyl rigid group to synergistically act with a flexible chain segment, improve the flowability, and reduce the contact reaction of a hydrophilic group with water and other media in the environment through steric hindrance of a hydrophobic benzene ring, thereby improving the high-temperature resistance and corrosion resistance of the epoxy sealant, so that the epoxy sealant has high reliability and good adhesion, and is easy to operate. By adding a triethylamine catalyst, the active hydrogen on the mercapto group is easily removed, and the nucleophilic addition reaction with the epoxy group is easy to occur, so that the rapid curing can be carried out at low temperature or normal temperature, and the epoxy sealant can be used as a sealant material for encapsulating photovoltaic cell devices. The preparation method of the epoxy sealant comprises preparation of a mercaptan curing agent, mixing of raw materials, stirring and molding, and the process is simple and the conditions are mild, which is beneficial to actual production.

[0006] To achieve the above-mentioned object, the present application provides an epoxy sealant, and the raw material components of the epoxy sealant include, based on the total weight of the epoxy sealant: 40-50wt% of a mercaptan curing agent, 40-50wt% of an epoxy resin, 1-5wt% of a curing accelerator and 1-5wt% of a diluent; wherein the mercaptan curing agent is a colorless transparent liquid formed by mixing and reacting pentaerythritol tetra-3-mercaptopropionate, triphenylmethyl glycidyl ether and triethylamine, and the molar ratio of pentaerythritol tetra-3-mercaptopropionate to triphenylmethyl glycidyl ether is 3:1-5:1.

[0007] As a further preferred technical scheme of the present application, the epoxy resin is a bisphenol A type epoxy resin.

[0008] As a further preferred technical scheme of the present application, the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, and / or the diluent is polypropylene glycol diglycidyl ether.

[0009] As a further preferred technical scheme of the present application, in the raw material components of the mercaptan curing agent, the molar ratio of pentaerythritol tetra-3-mercaptopropionate to triphenylmethyl glycidyl ether is 4:1, and the proportion of triethylamine is 0.5wt%.

[0010] As a further preferred technical scheme of the present application, the mercaptan curing agent is prepared by the following method:

[0011] Pentaerythritol tetra-3-mercaptopropionate and triphenylmethyl glycidyl ether are mixed, and triethylamine is added as a catalyst, a constant temperature water bath is maintained at 70-80℃ for 12-24h, and magnetic stirring is carried out at a speed of 200-400r / min, to obtain a colorless transparent liquid.

[0012] According to another aspect of the present application, the present application also provides a preparation method of the high-temperature-resistant and corrosion-resistant epoxy sealant, wherein 40-50 wt% of the polythiol curing agent, 40-50 wt% of the epoxy resin, 1-5 wt% of the curing accelerator and 1-5 wt% of the diluent are mixed and stirred uniformly, and then the mixed and stirred mixture is cured and shaped.

[0013] As a further preferred technical solution of the present application, in the preparation method of the epoxy sealant, the stirring condition of the mixing and stirring is that the stirring treatment is performed for 1-3 min by using a glass rod.

[0014] As a further preferred technical solution of the present application, in the preparation method of the epoxy sealant, the curing condition of the mixture curing and shaping includes that the mixture is dried at a constant temperature of 30-40℃ in an oven for 24-48 h.

[0015] According to another aspect of the present application, the present application also provides a use of the high-temperature-resistant and corrosion-resistant epoxy sealant as an electronic packaging material, such as a packaging material for perovskite photovoltaic cells, so that the high-temperature-resistant and corrosion-resistant epoxy sealant has excellent high-temperature-resistant and corrosion-resistant performance.

[0016] Compared with the prior art, the present application can achieve the following beneficial effects:

[0017] 1) The epoxy sealant of the present application introduces a triphenylmethyl rigid group, and the steric hindrance effect of the triphenylmethyl rigid group cooperates with the mercapto group to form a high-crosslinking-density network, which reduces the activation energy of the ring-opening reaction and shortens the gel time, has a high thermal weight loss temperature, and the hydrophobic group benzene ring blocks the penetration of water molecules, has good medium resistance, so that the epoxy sealant has high reliability, and also has good adhesion performance, is easy to operate, and can be used as a sealant material for packaging photovoltaic cell devices.

[0018] 2) The preparation method of the epoxy sealant of the present application uses a new type of polythiol curing agent, and through operations such as raw material mixing, stirring and shaping, the process is simple and the conditions are mild, which is beneficial to actual production. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0020] Fig. 1 The mass change of the different cured products obtained in Examples 1-3 and Comparative Examples 1-2 in water solution.

[0021] Fig. 2 The mass change of the different cured products obtained in Examples 1-3 and Comparative Examples 1-2 in anhydrous kerosene.

[0022] Fig. 3 The mass change of the different cured products obtained in Examples 1-3 and Comparative Examples 1-2 in HCl.

[0023] The objectives, functional characteristics and advantages of the present application will be further explained in conjunction with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0025] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present application belongs. The test reagents used in the following examples are conventional biochemical reagents unless otherwise specified; and the experimental methods described are conventional methods unless otherwise specified.

[0026] The following implementation examples use commercially available experimental materials as follows: pentaerythritol tetra-3-mercaptopropionate, purchased from China Reagent Co., Ltd.; trityl glycidyl ether, purchased from Beijing Huaweiruike Chemical Co., Ltd.; triethylamine, purchased from Shanghai Lingfeng Chemical Co., Ltd.; epoxy resin, bisphenol A type epoxy resin E51, purchased from Shanghai Maier Biotechnology Co., Ltd.; 2,4,6-tris(dimethylaminomethyl)phenol, DMP-30, purchased from China Reagent Co., Ltd.; polypropylene glycol diglycidyl ether, XY207, purchased from China Reagent Co., Ltd.; epoxy propyl phenyl ether, purchased from China Reagent Co., Ltd.; 2-toluene glycidyl ether, purchased from Shanghai Maier Biotechnology Co., Ltd.

[0027] Example 1

[0028] The preparation method of the epoxy sealant provided in this embodiment is as follows:

[0029] (1) Mix pentaerythritol tetra-3-mercaptopropionate and trityl glycidyl ether at a molar ratio of 4:1, use triethylamine (0.5wt%) as a catalyst, constant temperature 80℃ water bath for 12h, magnetic stirring speed 200-400r / min, to obtain colorless transparent liquid polythiol curing agent.

[0030] (2) Mix 45wt% polythiol curing agent prepared in step (1) and 45wt% epoxy resin by mass percentage, and add 5wt% diluent polypropylene glycol diglycidyl ether (XY207), 5wt% accelerator 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), and stir uniformly with a glass rod for 3min.

[0031] (3) The epoxy mixture obtained in step (2) is poured into the corresponding mold, and air bubbles are discharged in time with a glass rod. It is dried in an oven at 40°C for 24 hours. Finally, the epoxy sealant is obtained, denoted as A1.

[0032] Example 2

[0033] The preparation method of the epoxy sealant provided by the present embodiment is as follows:

[0034] (1) The pentaerythritol tetra-3-mercaptopropionate and the triphenylmethyl glycidyl ether are mixed at a molar ratio of 4:1. Triethylamine (0.5wt%) is used as a catalyst. The water bath is kept at 80°C for 12 hours. The magnetic stirring speed is 200-400r / min. A colorless transparent liquid polythiol curing agent is obtained.

[0035] (2) According to the mass percentage, 40wt% of the polythiol curing agent prepared in step (1) is mixed with 50wt% of the epoxy resin. 5wt% of XY207 diluent and 5wt% of DMP-30 accelerator are added. The glass rod is fully stirred and uniformly mixed for 3 minutes.

[0036] (3) The epoxy mixture obtained in step (2) is poured into the corresponding mold, and air bubbles are discharged in time with a glass rod. It is dried in an oven at 40°C for 24 hours. Finally, the epoxy sealant is obtained, denoted as A1.

[0037] Example 3

[0038] The preparation method of the epoxy sealant provided by the present embodiment is as follows:

[0039] (1) The pentaerythritol tetra-3-mercaptopropionate and the triphenylmethyl glycidyl ether are mixed at a molar ratio of 4:1. Triethylamine (0.5wt%) is used as a catalyst. The water bath is kept at 80°C for 12 hours. The magnetic stirring speed is 200-400r / min. A colorless transparent liquid polythiol curing agent is obtained.

[0040] (2) According to the mass percentage, 40wt% of the polythiol curing agent prepared in step (1) is mixed with 50wt% of the epoxy resin. 5wt% of XY207 diluent and 5wt% of DMP-30 accelerator are added. The glass rod is fully stirred and uniformly mixed for 3 minutes.

[0041] (3) The epoxy mixture obtained in step (2) is poured into the corresponding mold, and air bubbles are discharged in time with a glass rod. It is dried in an oven at 40°C for 24 hours. Finally, the epoxy sealant is obtained, denoted as A1.

[0042] Comparative Example 1

[0043] The same method as in Example 1 was used, except that the trityl glycidyl ether in the polythiol curative component was replaced with epoxy propyl phenyl ether, and the molar ratio of pentaerythritol tetra-3-mercaptopropionate to epoxy propyl phenyl ether was 4:1. The final epoxy sealant obtained in this comparative example is designated B1.

[0044] Comparative Example 2

[0045] The same method as in Example 1 was used, except that the trityl glycidyl ether in the polythiol curative component was replaced with 2-methyltrityl glycidyl ether, and the molar ratio of pentaerythritol tetra-3-mercaptopropionate to 2-methyltrityl glycidyl ether was 4:1. The final epoxy sealant obtained in this comparative example is designated B2.

[0046] Comparative Example 3

[0047] The same method as in Example 1 was used, except that the molar ratio of pentaerythritol tetra-3-mercaptopropionate to trityl glycidyl ether in the polythiol curative component was replaced with 1:1.

[0048] The polythiol curative prepared in Comparative Example 3 was a semi-solid, and could not be mixed with the epoxy resin subsequently, so that no epoxy sealant was obtained.

[0049] Comparative Example 4

[0050] The same method as in Example 1 was used, except that the components of the polythiol curative were pentaerythritol tetra-3-mercaptopropionate and trityl glycidyl ether in a molar ratio of 1:4.

[0051] The polythiol curative prepared in Comparative Example 4 was a solid, and could not be mixed with the epoxy resin subsequently, so that no epoxy sealant was obtained.

[0052] Comparative Example 5

[0053] The same method as in Example 1 was used, except that no polythiol curative was used, and pentaerythritol tetra-3-mercaptopropionate was mixed directly with the epoxy resin. The mixture could not be cured even after being dried in an oven at 40°C for 24 hours, so that no epoxy sealant was obtained.

[0054] Performance testing of the epoxy sealants:

[0055] 1) The thermal stability of the epoxy sealants A1-A3 and B1-B2 obtained in Examples 1-3 and Comparative Examples 1-2 was tested. The thermal stability was tested by TGA, with the following conditions: 3-5 mg of sample was placed in a crucible in the instrument, and the temperature was raised from 50-600°C at a rate of 20°C / min; nitrogen atmosphere.

[0056] The test results of thermal stability are shown in Table 1:

[0057] Table 1 Test indexes of thermal stability of epoxy sealant

[0058]

[0059] 2) Test the medium resistance performance indexes of the epoxy sealants A1-A3 and B1-B2 obtained from Test Examples 1-3 and Comparative Examples 1-2, and the obtained results are shown in Table 2. Figs. 1-3 Figs. 1-3 The medium resistance performance test indexes are as follows: the finally cured epoxy sealant is prepared into a homogeneous block sample with a size of 20x20x2mm by using a precision mold. The sample is immersed in different corrosion medium systems, specifically including water, industrial anhydrous kerosene, 0.5wt% hydrochloric acid solution, and is placed under constant temperature and humidity conditions for 15 days. During the experiment, the block is taken out every 24h and dried in an oven at 40℃ for 30min, weighed, and the weight data is recorded, and finally the degree of corrosion of the block is judged by the percentage of weight loss.

[0060] According to the test results in Table 1 and Figs. 1-3 It can be seen from the test results in Table 1 and Table 2 that the epoxy sealant prepared by the present application has excellent high temperature resistance and corrosion resistance, because the content of the rigid group benzene ring in Comparative Example 1 and Comparative Example 2 is small, the space steric hindrance effect of the benzene ring structure and the crosslinking activity of the mercapto group are poor, the three-dimensional network structure formed by the cured product is not stable enough, resulting in relatively poor thermal stability and corrosion resistance of the cured product. In Test Examples 1-3, the comprehensive performance of Test Example 1 is the best, and is significantly better than Comparative Examples 1 and 2. In addition, compared with Comparative Examples 1 and 2, the temperature at which Test Examples 2 and 3 lose 5% of weight is relatively high, but the temperature at which they lose 50% of weight is higher than that of Comparative Examples 1 and 2, indicating that they still have obvious advantages in high temperature resistance.

[0061] 3) The gel time of the epoxy sealant is tested. The gel time is determined according to the standard GB / T 16995-1997. The epoxy sealant before curing is used as an adhesive and is evenly coated in a specified mold at room temperature, and after timing, the adhesive is quickly stirred with a stick, and when the viscosity of the adhesive gradually increases and the stirring gradually becomes difficult, the stirring is stopped, the silk is started, and when the adhesive cannot be pulled, the timing is stopped, which is the gel time of the system. The test results are: the gel time of Test Examples 1-3 is less than 8min, and the gel time of Comparative Examples 1-2 is significantly longer than that of Test Examples 1-3, indicating that the epoxy sealant of the present application has an excellent operation time window and can be quickly cured after application.

[0062] ​Although the specific embodiments of the present application have been described above, it is understood by those skilled in the art that these are merely illustrative and various changes or modifications can be made to the present embodiments without departing from the principles and the spirit of the present application, and the scope of protection of the present application is defined only by the appended claims.

Claims

1. A high temperature resistant and corrosion resistant epoxy sealant, characterized in that: include: 40-50 wt% of a polythiol curing agent, 40-50 wt% of an epoxy resin, 1-5 wt% of a curing accelerator, and 1-5 wt% of a diluent; The polythiol curing agent is a colorless transparent liquid formed by mixing and reacting pentaerythritol tetrakis-3-mercaptopropionate, trityl glycidyl ether and triethylamine, wherein the molar ratio of pentaerythritol tetrakis-3-mercaptopropionate to trityl glycidyl ether is 3:1-5:

1.

2. The high temperature and corrosion resistant epoxy sealant according to claim 1, characterized in that: The epoxy resin is bisphenol A epoxy resin.

3. The high temperature and corrosion resistant epoxy sealant according to claim 1, characterized in that: The curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, and / or the diluent is polypropylene glycol diglycidyl ether.

4. The high temperature and corrosion resistant epoxy sealant according to claim 1, characterized in that: In the raw material components of the polythiol curing agent, the molar ratio of pentaerythritol tetrakis-3-mercaptopropionate and trityl glycidyl ether is 4:1, and the proportion of triethylamine is 0.5 wt %.

5. The high temperature and corrosion resistant epoxy sealant according to claim 1, characterized in that: The polythiol curing agent is prepared by the following method: Pentaerythritol tetrakis-3-mercaptopropionate and trityl glycidyl ether are mixed, and triethylamine is added as a catalyst. The mixture is placed in a water bath at a constant temperature of 70-80°C for 12-24 hours and magnetically stirred at a speed of 200-400 r / min to obtain a colorless transparent liquid.

6. A method for preparing the high temperature resistant and corrosion resistant epoxy sealant according to any one of claims 1 to 5, characterized in that: Calculated by mass percentage, 40-50 wt% of a polythiol curing agent, 40-50 wt% of an epoxy resin, 1-5 wt% of a curing accelerator and 1-5 wt% of a diluent are mixed and stirred uniformly, and then the stirred mixture is cured and formed.

7. The preparation method according to claim 6, characterized in that The stirring condition of the mixing is: stirring with a glass rod for 1-3 minutes.

8. The preparation method according to claim 6, characterized in that The curing conditions for the mixture curing molding include: drying at a constant temperature of 30-40° C. for 24-48 hours.

9. Use of the high temperature resistant and corrosion resistant epoxy sealant according to any one of claims 1 to 5 as an electronic packaging material.

10. The use according to claim 9, characterized in that The high-temperature-resistant and corrosion-resistant epoxy sealant is used as a packaging material for photovoltaic cells.

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