CN114891470B

CN114891470B - Epoxy sealant and preparation method thereof

Info

Publication number: CN114891470B
Application number: CN202210381442.XA
Authority: CN
Inventors: 张佳; 毛志平; 翟丹
Original assignee: Chongqing Bondrite New Material Co ltd
Current assignee: Chongqing Bondrite New Material Co ltd
Priority date: 2022-04-12
Filing date: 2022-04-12
Publication date: 2023-08-04
Anticipated expiration: 2042-04-12
Also published as: CN114891470A

Abstract

An epoxy sealant and a preparation method thereof, wherein the epoxy sealant comprises a component A and a component B, and the component A comprises the following components by mass: 40-52 parts of epoxy resin, 9-24 parts of multifunctional epoxy resin, 6-10 parts of diluent, 25-30 parts of filler, 0-3 parts of anti-settling agent, 0-3 parts of coupling agent and 0-3 parts of brightening agent; component B comprises a curing agent comprising a modified imidazole. The epoxy sealant has the characteristics of low water vapor permeation, oxygen barrier, low viscosity, low-temperature rapid solidification and the like through modification, and the reworkability is remarkably improved.

Description

Epoxy sealant and preparation method thereof

Technical Field

The invention relates to the field of materials, in particular to an epoxy sealant and a preparation method thereof.

Background

Electronic paper, also called digital paper and digital paper, is an ultrathin and ultralight display screen. The display effect is close to that of common paper, so that people can read comfortably, and the display device can display new contents in a conversion and refreshing mode like a common liquid crystal display. The electronic ink is coated on the display screen to display information such as characters and pictures. The electronic paper reduces the felling of wood, is beneficial to realizing green ecology, and is therefore sought after by people.

The electronic paper has the advantages of convenient reading, convenient carrying, large information storage capacity, resource saving, high transmission speed and the like, and the electronic paper is gradually integrated into the life of people due to the advantages, so that the electronic paper has wide development prospect.

The existing paper books are thicker, and the time of people is always scattered, so that only one whole book can be read, and only one book can be carried with people. Compared with paper books, the electronic paper has smaller volume, and ultrathin pages bring new reading physical examination to people, and only the content of the book is needed to be downloaded into the electronic paper. Under the condition that people want to read by using scattered time on buses and subways, people can see the content which the people want to see only by taking the electronic paper out of the bag to click and read. Although common mobile devices such as mobile phones and Pad also have the function of reading electronic books, the electronic paper is unfavorable for protecting eyes, and the electronic paper can protect eyes. The electronic paper simulates a paper book, and compared with a mobile phone, a Pad and the like, the electronic paper has the advantage that the eye protection effect is remarkably enhanced by adopting a non-backlight system.

Electronic paper can be regarded as a special film. People 'paint' electronic ink on the film and control the film in a background according to different contents so as to display information such as characters, pictures and the like. The display technology approaches of electronic paper are mainly divided into four types, namely cholesterol liquid crystal display technology (Ch-LCD), electrophoretic display technology (EPD), bistable nematic liquid crystal display technology (BiT NLCD) and electronic powder fluid display technology (QR-LPD). Four different display technologies have advantages and disadvantages, but the promotion of the development of electronic paper technology is undoubted.

The electronic paper screen is sensitive to water vapor and oxygen, and when the water vapor and the oxygen enter the device, the adhesiveness between the cathode and the light-emitting layer can be affected, so that chemical reaction occurs in the organic film layer. These all lead to dramatic degradation of the optoelectronic characteristics during the process, resulting in rapid degradation and failure of the device. Therefore, when the electronic paper screen is assembled, the frame needs to be sealed by a layer of glue capable of blocking water vapor and blocking oxygen permeation, the electronic screen component is not resistant to high temperature, and the frame belongs to a slot in the assembly process, so that the glue needs to have good fluidity. The existing glue can not meet the sealing requirement.

The existing sealant for sealing the electronic paper screen frame has poor flexibility, poor reworkability and poor barrier property, and needs to be solved.

Disclosure of Invention

According to a first aspect, in an embodiment, there is provided an epoxy sealant comprising a component a, a component B, the component a comprising by mass:

40-52 parts of epoxy resin, 9-24 parts of multifunctional epoxy resin, 6-10 parts of diluent, 25-30 parts of filler, 0-3 parts of anti-settling agent, 0-3 parts of coupling agent and 0-3 parts of brightening agent;

component B comprises a curing agent comprising a modified imidazole.

According to a second aspect, in an embodiment, there is provided a method for preparing the epoxy sealant according to the first aspect, including:

the preparation step of the component A comprises the steps of mixing epoxy resin, multifunctional epoxy resin, diluent, filler, anti-settling agent, coupling agent and brightening agent according to the formula amount to prepare the component A;

the preparation step of the component B comprises the steps of mixing all curing agents according to the formula amount to prepare the component B;

and mixing the component A and the component B according to the formula amount to obtain the sealant.

According to the epoxy sealant and the preparation method thereof, the epoxy sealant has the characteristics of low water vapor permeation, oxygen barrier, low viscosity, low-temperature rapid solidification and the like through modification, and the reworkability is remarkably improved.

Detailed Description

The present invention will be described in further detail with reference to the following specific embodiments. Wherein like elements in different embodiments are numbered alike in association. In the following embodiments, numerous specific details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted, or replaced by other elements, materials, or methods in different situations. In some instances, some operations associated with the present application have not been shown or described in the specification to avoid obscuring the core portions of the present application, and may not be necessary for a person skilled in the art to describe in detail the relevant operations based on the description herein and the general knowledge of one skilled in the art.

Furthermore, the described features, operations, or characteristics of the description may be combined in any suitable manner in various embodiments. Also, various steps or acts in the method descriptions may be interchanged or modified in a manner apparent to those of ordinary skill in the art. Thus, the various orders in the description are for clarity of description of only certain embodiments, and are not meant to be required, unless otherwise indicated, to be followed.

The numbering of the components itself, e.g. "first", "second", etc., is used herein merely to distinguish between the described objects and does not have any sequential or technical meaning. The terms "connected" and "coupled," as used herein, are intended to encompass both direct and indirect connections (couplings), unless specifically indicated otherwise.

In an embodiment, the invention provides an epoxy sealant applicable to the frame of an electronic paper display screen, which has the characteristics of low water vapor permeation, oxygen barrier, low viscosity, low-temperature rapid solidification and the like.

component B comprises a curing agent comprising a modified imidazole. Latent curing agents with low viscosity, high purity and long handling time are preferred.

The epoxy sealant finished product is prepared by mixing the component A and the component B, the component A and the component B do not need to be prepared and used at present when the epoxy sealant is used, the use convenience of the product is effectively improved, and the performance of the product is more stable.

In one embodiment, component a comprises the following components by mass:

40 to 52 parts of epoxy resin, 9 to 24 parts of multifunctional epoxy resin, 6 to 10 parts of diluent, 25 to 28.5 parts of filler, 0.5 to 3 parts of anti-settling agent, 0.5 to 3 parts of coupling agent and 0.5 to 3 parts of whitening agent.

In one embodiment, component a: component b= (100-110): (5-30).

In one embodiment, component a: component b= (100-110): 10.

in one embodiment, component a: component b= (100-101): 10.

in one embodiment, the curing agent is a homemade liquid imidazole modified curing agent. The polyol glycidyl ether with lower viscosity is used for reacting with imidazole, and H atom on the 1 position of the imidazole and epoxy group are subjected to addition reaction to prepare the low-viscosity flexible latent modified imidazole.

In one embodiment, the modified imidazoles include, but are not limited to, at least one of modified imidazoles (1), (2), and (3) shown in the following structures:

the structural formula of the modified imidazole (1) is as follows:

n is an integer of 1 to 3;

the structural formula of the modified imidazole (2) is as follows:

n is an integer of 1 to 3;

the structural formula of the modified imidazole (3) is as follows:

in one embodiment, the synthesis method of the modified imidazoles (1), (2) and (3) is specifically as follows:

modified imidazole (1): into a three-necked flask equipped with a stirrer, a dropping funnel and a condenser, 164g of 2-methylimidazole and xylene were put, and stirred and mixed at 110 to 120 ℃. 652g of polypropylene glycol diglycidyl ether were added dropwise at 120℃over 2h. The reaction product was insoluble in xylene, and after the reaction, the reaction product was separated from xylene, and the residual xylene was distilled off at 140℃and 1.3kPa to give a dark reddish brown liquid adduct as a sample.

Modified imidazole (2): 220g of 2-ethyl-4-methylimidazole and xylene were put into a three-necked flask equipped with a stirrer, a dropping funnel and a condenser, and stirred and mixed at 110 to 120 ℃. 652g of polypropylene glycol diglycidyl ether were added dropwise at 120℃over 2h. The reaction product was insoluble in xylene, and after the reaction, the reaction product was separated from xylene, and the residual xylene was distilled off at 140℃and 1.3kPa to give a dark reddish brown liquid adduct as a sample.

Modified imidazole (3): 220g of 2-ethyl-4-methylimidazole and xylene were put into a three-necked flask equipped with a stirrer, a dropping funnel and a condenser, and stirred and mixed at 110 to 120 ℃. 202g of butanediol diglycidyl ether were added dropwise at 120℃over 2h. The reaction product was insoluble in xylene, and after the reaction, the reaction product was separated from xylene, and the residual xylene was distilled off at 140℃and 1.3kPa to give a dark reddish brown liquid adduct as a sample.

In one embodiment, the epoxy resin includes, but is not limited to, at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac epoxy resin, aromatic polyacrylate type epoxy resin, hydrogenated epoxy resin, resorcinol diglycidyl ether (CAS number: 101-90-6), aliphatic alcohol polyglycidyl ether, and the like. Bisphenol F type epoxy resins of high purity and low viscosity are preferred.

In one embodiment, the multifunctional epoxy resin includes, but is not limited to, at least one of glycerol glycidyl ether (CAS number: 25038-04-4), pentaerythritol glycidyl ether (CAS number: 3126-63-4), triglycidyl meta-aminophenol (CAS number: 71604-74-5), tetraglycidyl diaminodiphenylmethane, N, N, N ', N' -tetraepoxypropyl-4, 4 '-diaminodiphenylmethane (CA number: 28768-32-3), 2',2"- [ methenyl-tris (phenoxymethylene) ] tris (ethylene oxide) (CAS number: 66072-38-6), ethylene oxide, 2- [ [2- (ethylene oxide YLmethoxy) -1, 3-phenyl ENE ] bis (methylene) ] bis- (CAS number: 13561-08-5), and the like, wherein low viscosity, high purity glycerol glycidyl ether is preferred.

In one embodiment, the diluent includes, but is not limited to, at least one of 4-tert-butylphenyl glycidyl ether (also known as p-tert-butylphenyl glycidyl ether, CAS registry number 3101-60-8), phenyl glycidyl ether (CAS registry number 122-60-1), 2-toluene glycidyl ether (also known as o-benzyl glycidyl ether, CAS registry number 2210-79-9), cyclohexanedimethanol diglycidyl ether, dipropylene glycol monomethyl ether, and the like. Preferably, a high purity diluent is used.

In one embodiment, the filler comprises at least one of an organic filler, an inorganic filler.

In one embodiment, the filler has an average particle size of 3 to 15 μm.

In one embodiment, the organic filler includes, but is not limited to, at least one of polyethylene (powder), polypropylene (powder), polyacrylonitrile (alias PAN, in powder form), polymethyl methacrylate (PMMA powder), ABS high rubber powder, polybutadiene rubber, and the like.

In one embodiment, the polybutadiene rubber comprises a polybutadiene rubber having a core-shell structure.

In one embodiment, the inorganic filler includes, but is not limited to, at least one of hydrophobic silica fume, talc, spherical silica, mica powder, montmorillonite, alumina, and the like. The inorganic filler can improve the water vapor barrier property of the epoxy system after curing in the system. The spherical silicon is spherical silicon dioxide.

In one embodiment, the inorganic filler is preferably at least one of flake hydrophobic silica micropowder, talc, mica powder, montmorillonite, alumina, and the like.

In one embodiment, the anti-settling agent includes, but is not limited to, fumed silica.

In one embodiment, the coupling agent includes, but is not limited to, at least one of gamma- (2, 3-epoxypropyl) propyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, N-aminoethyl-3-aminopropyl methyldimethoxy silane.

In one embodiment, the whitening agent includes, but is not limited to, titanium dioxide.

In an embodiment, the sealant is used for sealing the electronic paper display screen frame.

the preparation step of the component B comprises the steps of mixing all curing agents according to the formula amount to prepare the component B; if the component B is only one curing agent, the curing agent is weighed according to the formula amount.

The preparation steps of the component A and the component B are not sequential, and can be carried out at any one step or simultaneously.

In one embodiment, the temperature of the material during the mixing step is less than or equal to 10 ℃.

In one embodiment, in the mixing step, the relative humidity of the air is less than or equal to 30% when mixed.

In one embodiment, the mixing step is performed under vacuum.

The temperature and humidity functions are to reduce the activity of the system, improve the storage stability of the system, and the vacuum function is to extract bubbles, small molecules and partial water vapor in the system, so that the system stability is improved.

In one embodiment, the sealant prepared in the mixing step is stored at-40.+ -. 2 ℃. The main function of low-temperature storage is to reduce the activity of the product in the storage process and improve the storage Life (shell Life) of the product.

In one embodiment, component A is prepared by the steps of preparing component A and then refrigerating at-5℃for 10-12 hours. The refrigeration function is to reduce the temperature of the materials during mixing and the aim is to reduce the activity of the system.

In one embodiment, component B is prepared by a process wherein component B is prepared and then refrigerated at-5℃for 12 hours. The refrigeration function is to reduce the temperature of the materials during mixing and the aim is to reduce the activity of the system.

In one embodiment, the invention provides a low-viscosity low-temperature fast-curing single-component epoxy sealant which is applied to the frame sealing of an electronic paper display screen and has low water vapor and oxygen barrier. The invention realizes the water vapor blocking and oxygen blocking by reacting the multifunctional epoxy resin with the multifunctional hydrophobic curing agent to form a high-density network structure; using organic filler as system filler to reduce the modulus of the cured adhesive layer so as to meet the aging performance test of the product; the viscosity of the system is reduced by selecting low-viscosity main resin, a curing agent and a small amount of diluent, so that the process requirement of sealing the electronic paper frame is met; the high-purity resin, the curing agent, the filler, the diluent and the hydrophobic curing agent which has long operation time and can realize low-temperature curing are selected, and the special process is produced at low temperature, so that the long operation time is achieved, and the actual sizing requirement is met.

The preparation process according to the invention is described in further detail below in connection with several examples.

The preparation methods of the electronic paper sealants provided in examples 1 to 3 and comparative examples 1 to 6 are as follows:

1. preparation of component A

1. Weighing epoxy resin, multifunctional epoxy resin, diluent, coupling agent, whitening agent and anti-settling agent (gas silicon, namely gas phase silicon dioxide) according to the weight percentage of each raw material in the component A in the table 1 to the total weight of the raw materials, and stirring and mixing;

2. the organic filler is weighed and is divided into three batches with equal quantity and added into the reaction kettle in the step 1, the time interval of each batch is 15min, the mixture is stirred and mixed for 30min after the addition is finished, and then the vacuum is extracted for 2h under the condition of-0.98 Mpa.

3. And (3) putting the prepared component A (namely Part A) into a refrigerator at the temperature of minus 5 ℃ for refrigeration for 12 hours for later use.

2. Preparation of component B

4. The component B (i.e., part B) was measured according to the mass in Table 1, dispersed uniformly, and put into a refrigerator at-5℃for cold storage for 12 hours for use.

The synthesis method of the modified imidazole (1), (2) and (3) comprises the following specific steps:

modified imidazole (1): into a three-necked flask equipped with a stirrer, a dropping funnel and a condenser, 164g of 2-methylimidazole and xylene were put, and stirred and mixed at 110 to 120 ℃. 652g of polypropylene glycol diglycidyl ether were added dropwise at 120℃over 2h. The reaction product was insoluble in toluene, and after the reaction, the reaction product was separated from xylene, and the residual xylene was distilled off at 140℃and 1.3kPa to give a dark reddish brown liquid adduct as a sample. Commercially available xylenes are generally referred to as a mixture of three isomers of ortho-xylene, meta-xylene, and para-xylene.

Modified imidazole (2): 220g of 2-ethyl-4-methylimidazole and xylene were put into a three-necked flask equipped with a stirrer, a dropping funnel and a condenser, and stirred and mixed at 110 to 120 ℃. 652g of polypropylene glycol diglycidyl ether were added dropwise at 120℃over 2h. The reaction product was insoluble in toluene, and after the reaction, the reaction product was separated from xylene, and the residual xylene was distilled off at 140℃and 1.3kPa to give a dark reddish brown liquid adduct as a sample.

3. Preparation of finished products

5. Mixing the component A and the component B according to the mass ratio shown in the table 1, controlling the temperature of the materials to be lower than 10 ℃, controlling the relative humidity of air to be lower than 30%, stirring for 30min under vacuum, rapidly packaging, and storing at-40 ℃. In table 1, each numerical value is the mass fraction of the corresponding component.

In Table 1, bisphenol F type resins were purchased from DIC in Japan; cargo number EXA-830CRP.

Glycerol glycidyl ether was purchased from michaux, cat no EPON 812.

Pentaerythritol glycidyl ether was purchased from Nagase, japan under the trade designation Denacol EX-411.

P-tert-butylphenyl glycidyl ether is available from Adideraceae, japan under the designation ED-509S.

Polyethylene powder was purchased from Mitsui chemical, japan under the trade designation PM-200.

PMMA powder was purchased from Korea Shangjin chemical under the trade designation PMMA160.

Talc flakes were purchased from IMERYS under the trade designation MISTRON CB.

Ball silicon was purchased from Admatechs under the designation 50SQ-E20.

TS-720 was purchased from cabot, U.S.A.

Z-6040 was purchased from Japanese Korea. Z-6040 is gamma- (2, 3-epoxypropyl) propyl trimethoxy silane.

Titanium dioxide is purchased from japan stone stock, cat No. R930.

TABLE 1

PN-H and HX-3722 belong to modified imidazole latent curing agents and do not belong to polyether amine.

In Table 1, the average particle diameter of each filler was 3 to 15. Mu.m.

The sealants prepared in the above examples and comparative examples were subjected to the following performance tests: the final product was tested for viscosity, cure properties, water vapor permeability (Water Vapor Transmission Rate, WVTR for short), coefficient of thermal expansion, glass transition temperature, push-pull force and modulus after cure. The results are shown in Table 2.

The performance index of the test is as follows:

1. viscosity of the mixture

The test was performed using a rotational viscometer at 25 ℃ according to ASTM D2393 test method.

2. Curing Performance test

Differential Scanning Calorimetry (DSC) was used to obtain a DSC curing curve, in which the curing time in unit min at a temperature rise rate of 100 ℃/min and a constant temperature of 70 ℃ was recorded.

3. Water vapor permeability (Water Vapor Transmission Rate, WVTR for short) test

Test pieces of 100mm×100mm×1mm were prepared using a flat plate mold, oven cured for 60min at 80 ℃, tested using a water vapor transmission tester (Mocon), test conditions: 50 ℃/100% RH, units g/m ² *24h, thickness 1mm.

4. Coefficient of thermal expansion test (CTE)

The thermal expansion coefficient was tested using thermo-mechanical analysis (TMA) according to ASTMD696 standard, wherein the temperature rise rate was 3 ℃/min and the thermal expansion coefficient was in ppm/DEG C.

5. Glass transition temperature (Tg)

Test gel samples were prepared and cured at 80℃for 120min, and the glass transition temperature in degrees Celsius during heating from-60℃to 200℃was measured using a thermo-mechanical analysis (TMA) at a heating rate of 3 ℃/min.

6. Push-pull force test

The material PET (5X 5 mm) +glass was measured for push-pull according to ASTM D1002 test method, wherein the curing conditions were 60 minutes curing at 80℃in kg.

7. Modulus test

Test mode using dynamic thermo-mechanical analysis (DMA): the sample size of the stretching mode is 20 multiplied by 6 multiplied by 0.5mm (length, width and thickness respectively), the prepared adhesive film is placed in an oven and cured for 120min at 80 ℃, wherein the temperature rise rate of the DMA test is 3 ℃/min, the curve range is minus 60 ℃ to 200 ℃, and the modulus unit is N/mm ² 。

8. And (3) testing the pot life, namely taking the prepared finished product, sealing and packaging the finished product by using a 30mL syringe, standing the finished product at room temperature (25 ℃) and testing the viscosity once every 1 hour. Specifically, the viscosity is tested every 1 hour within 0 to 12 hours, the viscosity increase rate at 12 hours is less than 50 percent, namely ok, if not, no is judged to be unqualified. Increase rate = (measured viscosity-initial viscosity)/initial viscosity x 100%.

9. Reliability test

And (3) coating sealant on the frame of the electronic paper screen once, placing in an oven, curing at 80 ℃ for 60min, placing at normal temperature for more than 12 hours, and then performing reliability test. High temperature and high humidity: 60 ℃,80%1080h; high temperature and low humidity: 60 ℃,35%840h, one cycle.

Reliability determination: the screen is not blacked, not whitened and has no side loss, and is judged to be ok (i.e. qualified), otherwise, is judged to be no (i.e. unqualified).

The data results obtained from the test are shown in table 2.

In table 2, α1 generally means an expansion coefficient in a certain temperature range below Tg (glass transition temperature), and α2 generally means an expansion coefficient in a certain temperature range above Tg (glass transition temperature).

TABLE 2

In Table 2, the lower the modulus, the better its reworkability. Modulus is less than or equal to 2200N/mm ² (25 ℃) is defined as reworkability "ok".

As can be seen from Table 2, the test results of the adaptation period of the prepared epoxy sealant are ok, which shows that the viscosity increase rate is less than 50% in 12 hours, and the epoxy sealant has a longer pot life by using three kinds of modified imidazoles in examples 1 to 3 respectively; the modulus is lower, in particular 1500-1700N/mm ² Indicating that the reworkability is better.

The component B of comparative example 1 uses PN-H (powder) to prepare an epoxy sealant with a modulus of up to 2800N/mm ² Poor reworkability, no. The viscosity increase rate is more than or equal to 50% in 12 hours, the pot life is short, the viscosity is too high, and the glass transition temperature is too high. The viscosity of the epoxy sealant is too large, when a client is used, the dispensing speed is slow, the fluidity of the glue is slow, and the bit stream of a filling part is uneven.

Component B of comparative example 2 is HX-3722 (liquid) and the epoxy sealer prepared has a modulus of up to 3000N/mm ² Poor reworkability, no. And the viscosity is too high and the glass transition temperature is too high.

In comparative example 3, the epoxy sealer prepared without the addition of a diluent was too viscous, up to 2400cps. And the glass transition temperature is higher.

Component B of comparative example 4 is PN-H (powder) which causes the water vapor permeability of the prepared epoxy sealant to be too high; modulus up to 2500N/mm ² Poor reworkability, no. And the curing time is long and is up to 120min. And the water vapor permeability is as high as 13g/m ² *24h (sample thickness 1 mm), the water barrier was poor. And the glass transition temperature is higher.

The comparative example 5 does not use the component B, and the viscosity increase rate of the prepared epoxy sealant in 12 hours is more than or equal to 50 percent, and the pot life is short. And the curing time is longer and is up to 150min. And the water vapor permeability is as high as 13g/m ² *24h (sample thickness 1 mm), the water barrier was poor. And the glass transition temperature is too high.

The component B of the comparative example 6 is 20 parts by mass of HX-3722 (liquid), and after the prepared epoxy sealant is used for coating the frame of the electronic paper screen, the screen is blackened, whitened, damaged, and the like, the reliability is poor, and no is judged. And the water vapor permeability is as high as 12g/m ² *24h (sample thickness 1 mm), the water barrier was poor. And the glass transition temperature is too high.

The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.

Claims

1. An epoxy sealant is characterized by comprising a component A and a component B, wherein the component A comprises the following components in mass:

the component B comprises a curing agent, wherein the curing agent comprises modified imidazole;

the modified imidazole comprises at least one of modified imidazoles (1), (2) and (3) shown in the following structures:

the structural formula of the modified imidazole (1) is as follows:

；

n is an integer of 1 to 3;

the structural formula of the modified imidazole (2) is as follows:

；

n is an integer of 1 to 3;

the structural formula of the modified imidazole (3) is as follows:

；

the epoxy resin comprises at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, hydrogenated epoxy resin and resorcinol diglycidyl ether;

the multifunctional epoxy resin comprises at least one of glycerol glycidyl ether, bisphenol A bis (triethylene glycol glycidyl ether), triglycidyl meta-aminophenol, pentaerythritol glycidyl ether, tetraglycidyl diamino diphenyl methane, N, N, N ', N' -tetraepoxypropyl-4, 4 '-diamino diphenyl methane, 2' - [ methylene-tris (phenoxymethylene) ] tris (ethylene oxide), ethylene oxide, 2- [ [2- (ethylene oxide YL methoxy) -1, 3-phenyl ENE ] bis (methylene) ] bis-;

the filler comprises at least one of an organic filler and an inorganic filler;

the organic filler comprises at least one of polyethylene, polypropylene, polyacrylonitrile, polymethyl methacrylate, ABS high rubber powder and polybutadiene rubber;

the inorganic filler comprises at least one of hydrophobic silica micropowder, talcum powder, mica powder and montmorillonite.

2. The epoxy sealer as claimed in claim 1, wherein the component a comprises the following components by mass:

40 to 52 parts of epoxy resin, 9 to 24 parts of multifunctional epoxy resin, 6 to 10 parts of diluent, 25 to 28.5 parts of filler, 0.5 to 3 parts of anti-settling agent, 0.5 to 3 parts of coupling agent and 0.5 to 3 parts of brightening agent.

3. The epoxy sealer as claimed in claim 1 or 2, wherein the component a: component b= (100-110): (5-30).

4. The epoxy sealer as claimed in claim 1 or 2, wherein the component a: component b= (100-110): 10.

5. the epoxy sealer as claimed in claim 1 or 2, wherein the component a: component b= (100-101): 10.

6. the epoxy sealant according to claim 1 or 2, wherein the diluent comprises at least one of 4-tert-butylphenyl glycidyl ether, phenyl glycidyl ether, 2-toluene glycidyl ether, cyclohexanedimethanol diglycidyl ether, dipropylene glycol monomethyl ether.

7. The epoxy sealant according to claim 1 or 2, wherein the filler has an average particle diameter of 3 to 15 μm.

8. The epoxy sealer of claim 1 or 2, wherein the polybutadiene rubber comprises a polybutadiene rubber having a core-shell structure.

9. The epoxy sealant of claim 1 or 2, wherein the anti-settling agent comprises fumed silica.

10. The epoxy sealer of claim 1 or 2, wherein the coupling agent comprises at least one of gamma- (2, 3-glycidoxy) propyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, N-aminoethyl-3-aminopropyl methyldimethoxysilane.

11. The epoxy sealer of claim 1 or 2, wherein the whitening agent comprises titanium dioxide.

12. The epoxy sealant of claim 1 or 2, wherein the sealant is used to seal an electronic paper display bezel.

13. The method for preparing the epoxy sealant according to any one of claims 1 to 12, comprising the steps of:

14. The method of claim 13, wherein in the mixing step, the material temperature is less than or equal to 10 ℃;

in the mixing step, the relative humidity of air is less than or equal to 30 percent during mixing;

in the mixing step, the mixing is performed under vacuum.

15. The preparation method of claim 13, wherein after the component A is prepared, the component A is placed at-5 ℃ for refrigeration for 10-12 hours;

and (3) after the component B is prepared, placing the component B at the temperature of minus 5 ℃ for refrigeration for 10-12 hours.