Low-stress epoxy sealant with high water resistance and preparation method thereof

Abstract

The invention provides a low-stress epoxy sealant with high water resistance and a preparation method thereof. The epoxy sealant comprises epoxy resin, water-blocking rubber, an epoxy modified monomer with a specific structure, a water-blocking filler, a cationic initiator and an auxiliary agent, the epoxy modified monomer with the specific structure is obtained by modifying crown ether and a silane coupling agent containing an epoxy group and / or glycidyl ether containing a silane group. A silane coupling agent containing an epoxy group and / or glycidyl ether containing a silane group are / is used for modifying crown ether, so that the damage of the epoxy sealant to a device film layer due to stress change in a damp-heat aging process is effectively improved while the adhesive property is not lost, and the water resistance and damp-heat aging property of the epoxy sealant are effectively improved; the service life of a display device can be effectively prolonged when the adhesive is applied to sealing and bonding of the display device.

Description

Technical Field

[0001] The present invention belongs to the technical field of OLED display, and particularly relates to a high water-resistant epoxy sealant and a preparation method thereof. Background Art

[0002] OLED (Organic Light-Emitting Diode), also known as organic electro-luminescence; different from the liquid crystal of the traditional LCD that emits light by a backlight source, its light-emitting layer is an organic light-emitting material with the characteristic of electro-luminescence; due to its excellent performance that is unparalleled by other display technologies, such as self-luminescence, wide viewing angle, high contrast, low power consumption, high response rate, full colorization, flexibility and simple manufacturing process, etc., it fully meets the future development trend of the information display industry and better caters to the needs of the majority of consumers, and has developed rapidly.

[0003] However, there are still some problems to be solved urgently in the application of current OLED display technology. The most important one is that the organic light-emitting material in the OLED display device will show black spots after contacting water and oxygen, resulting in device aging, which seriously affects the life and stability of the OLED display. Therefore, the high water-resistant encapsulation problem of OLED display devices is one of the key factors affecting the development of OLED display devices at the present stage.

[0004] With the development of display sealants, more application problems have emerged. And the performance of the final application sealant during the aging process directly determines the final life of the OLED device. Therefore, the stability of the sealant under humid and hot conditions has always been concerned and solved.

[0005] CN106797685A discloses a sealant for an organic electro-luminescent (OLED) display element, which is combined with a cationic polymerizable compound and olefin-based rubber particles, providing a solution to the stability problem of an OLED sealant under high temperature and high humidity conditions, but the preparation process is complex and no clear compatibility solution is proposed.

[0006] CN113168055A discloses a sealant for a display element, which uses a curable resin, a polymerization initiator and / or a thermal curing agent, combined with a flexible structure, to obtain a flexible cured product with low modulus and high water vapor barrier property, but the overall water vapor barrier property is not high and it is difficult to be actually applied.

[0007] CN1835983A discloses a sealant for a flat panel display, which improves adhesion by introducing a cyclic ether structure into the composition, and further introduces a large amount of fluorine elements to improve the humid and hot performance, and finally obtains a curable resin composition with good moisture resistance and excellent adhesiveness, but it is difficult to solve the damage to the device film layer caused by the stress change of the sealant during the humid and hot aging process only from the aspect of improving adhesion.

[0008] Therefore, it is expected to develop a low-stress epoxy sealant with high water resistance, which has excellent performance in both hygrothermal aging and thermal shock while having a certain adhesive force, so as to solve the above technical problems. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a high-water-resistance epoxy sealant, its preparation method and application. The epoxy sealant has high water resistance and hygrothermal aging properties, so that when it is applied to the sealing and bonding of display devices, it can effectively extend the device life and stability.

[0010] To achieve this purpose, the present invention adopts the following technical solutions:

[0011] In the first aspect, the present invention provides a low-stress epoxy sealant with high water resistance. The epoxy sealant comprises the following components in parts by weight:

[0012]

[0013]

[0014] The specific structure-modified epoxy monomer is modified by crown ether and a silane coupling agent containing an epoxy group and / or a glycidyl ether containing a silyl group.

[0015] As a preferred solution, the epoxy sealant comprises the following components in parts by weight:

[0016]

[0017] The high-water-resistance low-stress epoxy sealant provided by the present invention comprises a combination of specific parts of epoxy resin, water-resistant rubber, specific structure-modified epoxy monomer, water-resistant filler, and cationic initiator, and the specific structure-modified epoxy monomer is modified by crown ether and a silane coupling agent containing an epoxy group and / or a glycidyl ether containing a silyl group; the specific structure-modified epoxy monomer is a rigid matrix grafted with a flexible chain segment. The crown ether endows the system with a rigid network to ensure the hygrothermal aging performance. At the same time, the introduction of a toughenable epoxy silane chain segment further ensures the adhesive force of the system and the stress release during the aging process, and can effectively reduce the risk of damage to the device film layer caused by stress changes during the aging process. Combined with the specific epoxy resin compounding system, it can overall solve the high water resistance and aging performance requirements of OLED devices for the sealant, effectively improve the device stability, and extend the device service life.

[0018] The viscosity of the high water-resistance and low-stress epoxy sealant provided by the present invention is not less than 20 w cps. Its damp heat aging property has a reliability > 1000 h under the conditions of 85°C and 85% RH. Its water vapor barrier property is measured according to ISO 15106-2, and the water vapor transmission rate of the cured product with a thickness of 150 μm is less than 1.2 g / m 2 ·24 h.

[0019] Preferably, the addition amount of the specific structure-modified epoxy monomer is not less than 3 parts by weight.

[0020] Preferably, the crown ether main ring contains 6 to 20 carbon atoms, and more preferably 10 to 18 carbon atoms.

[0021] Preferably, the type of crown ether is one or a combination of hydroxy crown ether, benzo crown ether or cyclic crown ether; more preferably, it is hydroxy crown ether.

[0022] Preferably, the number of hydroxyl groups contained in the hydroxy crown ether is 1 to 5, and more preferably 1 - 3.

[0023] Preferably, the crown ether is selected from 18-crown-6 ether, 15-crown-5 ether, 2-hydroxymethyl-12-crown-4 ether, dibenzo-18-crown-6 ether, etc.

[0024] Preferably, the silane coupling agent containing an epoxy group is preferably one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 3-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0025] The glycidyl ether containing a silyl group is obtained by reacting component A and component B. Component A is a thiol-terminated siloxane, including 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptomethyltrimethoxysilane, 3-mercaptomethyltriethoxysilane, etc.; Component B is a glycidyl ether with a double bond, such as bisphenol A type diallyl diglycidyl ether, etc.

[0026] Preferably, the mol ratio of component A to component B is (1.5 - 2.5):1.

[0027] Preferably, the mol ratio of thiol to double bond is 1:1.

[0028] Preferably, the reaction of component A and component B can be carried out by UV irradiation in the presence of a free radical photoinitiator. In the present invention, the type of free radical photoinitiator is not particularly limited.

[0029] Preferably, the molar ratio of the crown ether to the silane coupling agent with an epoxy group and / or the glycidyl ether containing a silyl group is 1:(3-5).

[0030] Preferably, the specific structure-modified epoxy monomer is obtained by modifying the crown ether with a silane coupling agent containing an epoxy group and / or a glycidyl ether containing a silyl group at 60-90 °C for 4-5 h.

[0031] Preferably, the types of the epoxy resin are any one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidylamine epoxy resin, resorcinol epoxy resin, biphenyl epoxy resin, thioether epoxy resin, diphenyl ether epoxy resin, dicyclopentadiene epoxy resin, naphthalene epoxy resin, alkyl polyol epoxy resin, and rubber-modified epoxy resin.

[0032] Preferably, the water-blocking rubber is one or more of polyisobutylene, polybutene, and polybutadiene.

[0033] Preferably, the water-blocking rubber is polyisobutylene, more preferably a composition of different molecular weights; preferably, for the polyisobutylene of different molecular weights, the small molecular weight is 2000-6000, more preferably 2000-4000, the medium molecular weight is 10,000-70,000, more preferably 20,000-60,000. Preferably, the mass ratio of the small molecular weight to the medium molecular weight is 1:(1-4), more preferably 1:(2-3).

[0034] Preferably, the cationic initiator includes ionic aromatic diazonium salts, diaryliodonium salts, triarylsulfonium salts, alkylsulfonium salts, iron arene salts, etc., and non-ionic photoacid-generating photo-cationic polymerization initiators, such as nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenol sulfonate esters, diazonaphthoquinones, N-hydroxyimide sulfonate esters, etc. can be cited.

[0035] Preferably, the water-blocking filler is any one or more of alkali metal oxides, silica, and talc.

[0036] Preferably, the alkali metal oxides include one or more of calcium oxide, magnesium oxide, aluminum oxide, and zinc oxide.

[0037] Preferably, the water-blocking filler is a composition of different levels of particle size, more preferably a combination of micron-level and nano-level sizes; preferably, the mass ratio of different particle sizes is 1:1.

[0038] Preferably, the content of the auxiliary agent in the epoxy sealant is 0.3-7 parts by weight.

[0039] Preferably, the auxiliary agent includes one or more of defoamers, inhibitors, coupling agents, or leveling agents.

[0040] In addition, the present invention also provides a method for preparing the epoxy sealant, which comprises the following steps: mixing epoxy resin, water-blocking rubber, a specific structure-modified epoxy monomer, water-blocking filler, cationic initiator and additives to obtain the epoxy sealant.

[0041] Preferably, in the method for preparing the epoxy sealant, the mixing time is not less than 2 h.

[0042] Preferably, in the method for preparing the epoxy sealant, the mixing is carried out under stirring conditions. The rotation speed of the stirring is not less than 1500 rpm.

[0043] Preferably, in the method for preparing the epoxy sealant, the feeding sequence is as follows: the specific structure-modified epoxy monomer and water-blocking rubber are mixed for not less than 40 min and at a rotation speed not less than 2000 rpm, then epoxy resin, water-blocking filler and cationic initiator are added in sequence. After mixing at 1500 rpm - 2000 rpm for 20 min, additives are added, and stirring is carried out at 1800 rpm - 2000 rpm for not less than 20 min.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The high water-blocking and low-stress epoxy sealant provided by the present invention comprises a combination of specific amounts of epoxy resin, water-blocking rubber, a specific structure-modified epoxy monomer, water-blocking filler and cationic initiator. Among them, the special epoxy modifier is a rigid matrix grafted with a flexible segment. The crown ether endows the system with a rigid network to ensure the moisture and heat aging resistance. At the same time, a toughenable epoxy silane segment is introduced to further ensure the adhesion of the system and the stress release during the aging process, which can effectively reduce the risk of damage to the device film layer caused by stress changes during the aging process. Combined with the specific epoxy resin compounding system, it can overall solve the high water-blocking and aging performance requirements of OLED devices for the sealant, effectively improve the device stability and extend the service life of the device. Detailed Embodiments

[0046] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0047] (1) The raw material information involved in the detailed embodiments of the present invention is as follows:

[0048] Bisphenol A epoxy resin (EXA-850CRP): DIC resin, industrial product;

[0049] Bisphenol F epoxy resin (EXA-830CRP): DIC resin, industrial product;

[0050] Polyisobutylene: Nanjing Guochen, industrial product;

[0051] 3-Glycidoxypropyltrimethoxysilane: Shin-Etsu, industrial product;

[0052] 3-Mercaptopropyltrimethoxysilane: Shin-Etsu, industrial product;

[0053] 3-Mercaptopropyltriethoxysilane: Shin-Etsu, industrial product;

[0054] Bisphenol A diallyl diglycidyl ether: Anhui Xinyuan, industrial product;

[0055] Talcum powder: Imifab, industrial product;

[0056] Diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate: San-Apro, reagent grade.

[0057] (2) The main instruments and equipment information involved in the specific implementation part of the present invention is as follows:

[0058] Viscosity testing instrument: Cone-plate viscometer, Brookfield, USA;

[0059] High temperature and high humidity aging oven, Espec;

[0060] Thermal shock test chamber: Suzhou Zhihe;

[0061] Universal material testing machine: Jinan Sida;

[0062] Water vapor transmission rate tester: Mocon model 3.

[0063] Preparation Example 1

[0064] (1) Add 392.68 g of 3-mercaptopropyltrimethoxysilane and 420 g of bisphenol A diallyl diglycidyl ether into a reaction flask equipped with a stirring device, a temperature control device, and a condensation device. Introduce the inert protective gas nitrogen, and react at a rotation speed of 200 rpm for 10 min under UV light irradiation. Analyze the content of double bond groups with an infrared spectrometer. After the disappearance of the unsaturated double bond peak, a glycidyl ether containing a silyl group is obtained;

[0065] (2) Add 196.22 g of 2-hydroxymethyl-18-crown-6 to the product obtained in step (1) in the reaction flask, and continue to react for 4 h under the stirring conditions of 60 °C and 1500 rpm to obtain the specific structure modified epoxy monomer.

[0066] Preparation Example 2

[0067] (1) Add 476.84 g of 3-mercaptopropyltriethoxysilane and 420 g of bisphenol A diallyl diglycidyl ether into a reaction flask equipped with a stirring device, a temperature control device, and a condensation device. Introduce the inert protective gas nitrogen, and react at a rotation speed of 200 rpm for 10 min under UV light irradiation. Analyze the content of double bond groups with an infrared spectrometer. After the disappearance of the unsaturated double bond peak, a glycidyl ether containing a silyl group is obtained;

[0068] (2) Add 196.22 g of 2-hydroxymethyl-18-crown-6 to the reaction flask in step (1), and continue to react for 4 h under stirring conditions of 90 °C and 1500 rpm to obtain the specific structure modified epoxy monomer.

[0069] Preparation Example 3

[0070] React 196.22 g of 2-hydroxymethyl-18-crown-6 and 472.68 g of 3-glycidyloxypropyltrimethoxysilane under stirring conditions of 60 °C and 1500 rpm for 4 h to obtain the specific structure modified epoxy monomer.

[0071] Examples 1-5 and Comparative Examples 1-3

[0072] Add the specific structure modified epoxy monomer and the water-blocking rubber into a double planetary stirring kettle. Control the temperature at 25 °C and the vacuum condition at a gauge pressure of -0.1 MPa. After stirring at a rotation speed of 2000 rpm for 40 min, add epoxy resin, water-blocking filler, and cationic initiator in sequence and stir at a rotation speed of 2000 rpm for 40 min. Finally, add optional additives and stir at a rotation speed of 1000 rpm for 30 min, stir at a rotation speed of 1500 rpm for 30 min, stir at a rotation speed of 2000 rpm for 40 min, and finally take out after depressurization to obtain an epoxy sealant.

[0073] The raw material selection and dosage of each component in the above Examples 1-5 and Comparative Examples 1-3 are shown in Table 1, where the unit of dosage is "g".

[0074] Table 1 Raw materials and dosages of examples and comparative examples

[0075]

[0076]

[0077] Performance test:

[0078] (1) Water vapor barrier property: Test with a Mocon Model 3 water vapor barrier property tester, and take the average value after testing three times;

[0079] (2) Viscosity test: Use a cone-plate viscometer, rotor 52#, 2 rpm, and conduct the test three times to obtain the average value.

[0080] (3) Adhesion strength: Apply the present invention between two glass plates (thickness 15 μm), and cure it by UV light irradiation with an LED ultraviolet light at a wavelength of 365 nm (2500 mJ / cm 2 ) to achieve adhesion. Test the adhesion strength when pulling and breaking these two substrates at a speed of 5 mm / min.

[0081] (4) Double 85 high-temperature and high-humidity aging test: Apply the present invention to the actual OLED device packaging. After curing, place it under the conditions of 85°C / 85% RH, and measure the time when the device packaging remains non-failed.

[0082] (5) Thermal shock test: After curing the bonded specimen, cycle it under the conditions of -40°C / 30 min and 80°C / 30 min. Test the adhesion strength when pulling and breaking these two substrates at a speed of 5 mm / min, and measure the number of cycles with an adhesion strength > 90% of the initial adhesion strength.

[0083] (15) Aging adhesion strength: After curing the bonded specimen, place it under the conditions of 85°C / 85% RH for 1000 h, and test the adhesion strength when pulling and breaking these two substrates at a speed of 5 mm / min.

[0084] Test the UV printing inks provided in Examples 1 - 5 and Comparative Examples 1 - 3 according to the above test methods, and the test results are shown in Table 2.

[0085] Table 2 Test results of examples and comparative examples

[0086]

[0087]

[0088] It can be seen from the data in Table 2 that the high-water-resistance and low-stress epoxy sealant provided by the present invention has excellent water vapor barrier properties, resistance to heat and humidity aging, and high and low temperature shock properties. After aging, the adhesion strength retention rate is high, which generally meets the requirements of OLED devices for the high-water-resistance and aging performance of the sealant, effectively improves the device stability, and extends the device service life.

[0089] The applicant declares that the present invention uses the above examples to illustrate a high-water-resistance epoxy sealant and its preparation method and application, but the present invention is not limited to the above examples, that is, it does not mean that the present invention must rely on the above examples to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the present invention's product, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and public disclosure scope of the present invention.

Claims

1. A high water-resistance and low stress epoxy sealant, the epoxy sealant comprising the following components by weight parts: The specific structure modified epoxy monomer is obtained by modifying crown ether with a silane coupling agent containing an epoxy group and / or a glycidyl ether containing a silyl group.

2. The epoxy sealant according to claim 1, wherein, it comprises the following components:

3. The epoxy sealant according to claim 1 or 2, wherein, the crown ether main ring contains 6-20 carbon atoms, preferably 10-18 carbon atoms; the crown ether is one or more of hydroxy crown ether, benzo crown ether or cyclic crown ether; the crown ether is more preferably selected from 18-crown-6 ether, 15-crown-5 ether, 2-hydroxymethyl-12-crown-4 ether, dibenzo-18-crown-6 ether.

4. The epoxy sealant according to any one of claims 1 to 3, wherein, the crown ether is hydroxy crown ether, and the number of hydroxyl groups contained in the hydroxy crown ether is 1-5, preferably 1-3.

5. The epoxy sealant according to any one of claims 1 to 4, wherein, the silane coupling agent containing an epoxy group is selected from one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 3-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

6. The epoxy sealant according to any one of claims 1 to 5, wherein, the glycidyl ether containing a silyl group is obtained by reacting component A with component B. Component A is a siloxane with a mercapto group at the end, including one or more of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptomethyltrimethoxysilane, 3-mercaptomethyltriethoxysilane; Component B is a glycidyl ether with a double bond, preferably bisphenol A diallyl diglycidyl ether; preferably, the molar ratio of component A to component B is (1.5-2.5):1; the molar ratio of mercapto group to double bond is 1:

1.

7. The epoxy sealant according to any one of claims 1 to 6, wherein, the molar ratio of crown ether to the silane coupling agent with an epoxy group and / or the glycidyl ether containing a silyl group is 1:(3-5).

8. The epoxy sealant according to any one of claims 1 to 7, wherein, the epoxy resin is selected from one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidylamine epoxy resin, resorcinol epoxy resin, biphenyl epoxy resin, thioether epoxy resin, diphenyl ether epoxy resin, dicyclopentadiene epoxy resin, naphthalene epoxy resin, alkyl polyol epoxy resin, rubber modified epoxy resin.

9. The epoxy sealant according to any one of claims 1 to 8, wherein, The water-blocking rubber is one or more of polyisobutylene, polybutene, and polybutadiene; preferably, the water-blocking rubber is polyisobutylene, and more preferably a polyisobutylene composition with different molecular weights, where the low molecular weight is 2,000 to 6,000, preferably 2,000 to 4,000, the medium molecular weight is 10,000 to 70,000, preferably 20,000 to 60,000; preferably, the mass ratio of the low molecular weight to the medium molecular weight is 1:(1 to 4), and more preferably 1:(2 to 3).

10. A method for preparing an epoxy sealant according to any one of claims 1 to 9, comprising the following steps: Mixing epoxy resin, water-blocking rubber, a specifically structured modified epoxy monomer, water-blocking filler, cationic initiator, and auxiliary agent to obtain the epoxy sealant.

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