UV and heat dual-curing packaging adhesive for reworkable display equipment and preparation method of UV and heat dual-curing packaging adhesive

Abstract

The invention discloses a UV and heat dual-curing packaging adhesive for reworkable display equipment and a preparation method of the UV and heat dual-curing packaging adhesive. Comprising the following raw materials in parts by weight: 30-40 parts of modified dual-cured epoxy methacrylate, 35-45 parts of a methacrylate diluent, 2-3 parts of a photoinitiator, 0.1-0.3 part of a defoaming agent, 1-2 parts of a silane coupling agent, 10-15 parts of a toughening agent and 5-8 parts of an epoxy curing agent. After the packaging adhesive is cured, a soft plastic blade can be used for complete stripping operation through heating, and the packaging adhesive has the advantages of being capable of being repaired to reduce operation errors, fast in shaping, fast in drying, high in adhesive strength, high in weather resistance and low in water permeability.

Description

Technical Field

[0001] The present invention relates to the field of display screens, and is mainly applied to electronic paper book display screens, and in particular to a UV and heat dual-curing encapsulation adhesive for a reworkable display device and a preparation method thereof. Background Art

[0002] The screen of the electronic paper book does not emit light itself, but displays content through natural light sources or auxiliary light sources, which has the characteristics of eye protection and power saving. The screen of the electronic paper book is mainly composed of glass, FPL (electronic ink film), IC (chip), FPC (flexible circuit board) and glass plate. The electronic ink film is greatly affected by moisture and heat. Sealing it on the glass with glue can effectively reduce the damage rate of the screen. Therefore, the quality of the packaging material directly affects the display effect of the display screen. Traditional epoxy encapsulation glue and UV and heat dual-curing encapsulation glue are non-repairable encapsulation glue. In the normal packaging process, a series of problems such as slight bubbles, packaging errors, and glue errors will occur, resulting in the appearance of defective products. However, performance inspection can only be carried out when the encapsulation glue is completely cured, so errors will result in the appearance of scrapped products. In order to meet the requirements of improving production efficiency and reducing costs, the repairable UV and heat dual-curing encapsulation glue with epoxy acrylate as the main component has become a new packaging material, but it has the problem of residual and powder foreign matter caused by broken glue strips, which pollutes the electronic paper book and produces scrapped products. Moreover, in pursuit of repairability, the dual-curing encapsulation adhesive with epoxy acrylate as the main component has poor double 85 aging, water permeability and bonding performance, which greatly reduces the service life of the e-paper book and has poor overall use value. Summary of the invention

[0003] In order to solve the above-mentioned problems existing in the existing packaging glue, the present invention provides a UV and heat dual-curing packaging glue for a reworkable display device and a preparation method thereof, aiming to reduce the viscosity of the cured packaging glue when heated through the coordination of various components so that rework operations can be performed, and reduce the generation of powdery objects in the process of rework and scraping, thereby reducing damage to the screen of the electronic paper book.

[0004] In order to achieve the purpose, the present invention adopts the following technical scheme:

[0005] A UV and heat dual-curing encapsulant for a reworkable display device is characterized in that the encapsulant comprises the following raw materials in parts by weight: 30-40 parts of modified dual-curing epoxy methacrylate, 35-45 parts of methacrylate diluent, 2-3 parts of photoinitiator, 0.1-0.3 parts of defoamer, 1-2 parts of silane coupling agent, 10-15 parts of toughening agent, and 5-8 parts of epoxy curing agent.

[0006] Furthermore, the modified dual-curing epoxy methacrylate is prepared as follows: 45-55 parts by weight of bisphenol F epoxy resin is added to a reactor, the temperature is raised to 75° C.-85° C. and stirred under nitrogen protection, 0.7-0.9 parts by weight of catalyst triethylbenzyl ammonium chloride and 20-30 parts by weight of methacrylic acid are added dropwise at a constant temperature, after the addition is completed, the temperature is raised to 115° C.-125° C. and the temperature is kept for reaction, the reaction is stopped when the acid value is less than 1 mgKOH / g, and the material is discharged hot to obtain the modified dual-curing epoxy methacrylate.

[0007] Furthermore, the methacrylate diluent is one or more of trimethylolpropane trimethacrylate, isobornyl methacrylate, isobornyl acrylate and polyethylene glycol (200) dimethacrylate.

[0008] Furthermore, the photoinitiator is one or more of photoinitiator ITX, photoinitiator TMO, photoinitiator 819 and photoinitiator 184.

[0009] Furthermore, the defoaming agent is one or more of BYK-016, YT-3300 and QM-2068.

[0010] Furthermore, the silane coupling agent may be KH-560.

[0011] Furthermore, the toughening agent is one or more of MX-154, IB7774 and 402.

[0012] Furthermore, the epoxy curing agent can be selected from one or more of epoxy curing agents CHAPA, D230 and Gaskamine 240.

[0013] The present invention also provides a method for preparing the UV and heat dual-curing packaging adhesive for the display device, comprising the following steps:

[0014] Step 1, add a photoinitiator to a methacrylate diluent, heat in a water bath at 60°C-70°C to dissolve and stir until clear and transparent, then add modified dual-curing epoxy methacrylate, defoamer, silane coupling agent and toughening agent, stir at a speed of 1000-1500 rpm for 30-50 minutes, and then cool to 15°C-20°C;

[0015] Step 2: Add epoxy curing agent to the material obtained in step 1, stir at a speed of 300-400 rpm for 10-15 minutes, maintain the material temperature at 15°C-20°C during stirring, filter, vacuum degas, and can to obtain UV and heat dual-curing packaging glue for repairable display devices.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. The modified dual-curing epoxy methacrylate in the encapsulation adhesive of the present invention is used in combination with a methacrylate diluent (such as trimethylolpropane trimethacrylate) and a toughening agent (such as MK-154). When the fully cured encapsulation adhesive is heated at 90-100°C, the presence of the methacrylate diluent intensifies the softening of the encapsulation adhesive and rapidly softens the hardness. The toughening agent makes the toughness of the adhesive strip stronger and does not generate additional powder or damage, so that the encapsulation adhesive has a repairable effect. Specifically: the molecular structure of the modified dual-curing epoxy methacrylate has two functional groups with different curing modes, which can connect the epoxy component and the UV curing component in the entire system into a whole at the molecular level, making it easier for the entire system to form a three-dimensional network structure, thereby forming a very good barrier surface. At the same time, this bonding mode is tight and not dense, and it becomes soft after heating, and can be peeled off and repaired. However, the modified resin alone cannot meet the requirements of repairability. In order to better improve the repairability, the present invention is combined with a soft trifunctional monomer such as trimethylolpropane trimethacrylate. The overall hardness of this monomer will quickly soften at 95°C. Combined with modified dual-curing epoxy methacrylate, the repairability becomes possible, and the dual 85 aging, water permeability and bonding performance are all guaranteed.

[0018] 2. The UV curing and shaping time of the packaging glue of the present invention is short, and the workpiece can proceed to the next process after shaping. In addition, the glue is stable in storage and easy to operate.

[0019] 3. The encapsulation adhesive of the present invention has passed the encapsulation simulation test and has excellent moisture and heat resistance.

[0020] 4. The encapsulation adhesive of the present invention has excellent bonding performance, is 100% solid, contains no volatile components, does not produce toxic or harmful substances during curing, and is green and environmentally friendly. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail. The following content is only an example and explanation of the concept of the present invention. The technicians in the relevant technical field can make various modifications or supplements to the specific implementation cases described or replace them with similar methods. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0022] Unless otherwise specified, all raw materials used in the following examples were purchased from the market.

[0023] Example 1

[0024] The modified dual-curing epoxy methacrylate used in this embodiment is prepared as follows: 50 g of bisphenol F epoxy resin is added to a reactor, the temperature is raised to 80° C. and stirred under nitrogen protection, 0.75 g of catalyst triethylbenzylammonium chloride and 25 g of methacrylic acid are added dropwise at a constant temperature of 80° C., after the addition is completed, the temperature is raised to 120° C. and the reaction is kept warm for 2 hours to make the acid value less than 1 mgKOH / g, the reaction is stopped, and the material is discharged hot to obtain the modified dual-curing epoxy methacrylate.

[0025] In this embodiment, the encapsulation glue is prepared according to the following steps:

[0026] Step 1, take 23.8g of isobornyl methacrylate and 17.9g of trimethylolpropane trimethacrylate, add 0.12g of photoinitiator ITX, 1.79g of photoinitiator TMO, and 0.59g of photoinitiator 819, heat in a 70°C water bath to dissolve and stir until clear and transparent, then add 35.8g of modified dual-curing epoxy methacrylate, 0.2g of defoamer YT-3300, 1.8g of silane coupling agent KH-560, and 12g of toughening agent MX-154, stir at a speed of 1300rpm for 40 minutes to evenly disperse the components, and then cool to 15°C-20°C.

[0027] Step 2: Add 6 g of epoxy curing agent CHAPA to the material obtained in step 1, stir at a speed of 320 rpm for 12 minutes, maintain the material temperature at 15°C-20°C during stirring, filter, vacuum degas, and can to obtain a UV and heat dual-curing packaging adhesive for display devices.

[0028] Comparative Example 1

[0029] In this comparative example, encapsulation adhesive was prepared in the same manner as in Example 1, except that trimethylolpropane trimethacrylate was replaced with an equal amount of trimethylolpropane triacrylate (Changxing EM231).

[0030] Comparative Example 2

[0031] In this comparative example, encapsulation adhesive was prepared in the same manner as in Example 1, except that trimethylolpropane trimethacrylate was replaced with an equal amount of propoxylated trimethylolpropane triacrylate (Changxing EM2381).

[0032] Comparative Example 3

[0033] In this comparative example, the encapsulation adhesive was prepared in the same manner as in Example 1, except that the amount of trimethylolpropane trimethacrylate was reduced by 10 g to 7.9 g.

[0034] Comparative Example 4

[0035] In this comparative example, encapsulation adhesive was prepared in the same manner as in Example 1, except that the amount of trimethylolpropane trimethacrylate was increased by 10 g to 27.9 g.

[0036] Comparative Example 5

[0037] In this comparative example, the encapsulation adhesive was prepared in the same manner as in Example 1, except that MK-154 was removed.

[0038] The following performance tests were performed on the packaging adhesives of each embodiment and comparative example:

[0039] 1. Reworkability

[0040] Test method: Use a dispensing machine to make a 2.5mm glue strip on the glass. After it is completely cured, briefly heat it at 95°C on a hot plate, and use a plastic blade to perform repair and scrape operations.

[0041] Test equipment: three-axis linkage dispensing machine TFT-331, electric heating plate DB-XAB.

[0042] 2. Water permeability

[0043] Test method: The encapsulation adhesive is made into a thin sheet with a thickness of 0.25 microns.

[0044] Test conditions: 50℃, 100%RH.

[0045] Test instrument: Water vapor transmission rate tester, Saicheng WPT-203.

[0046] 3. Moisture and heat resistance

[0047] Test method: Place the moisture-changing color silicone between two pieces of glass, seal the four sides with packaging glue, and after curing, place the sample in a constant temperature and humidity cycle box (50°C, 100% humidity) to observe the color change time of the silicone.

[0048] Test instrument: Hongjin Instrument HTK-TH-100DH.

[0049] 4. Resistance to high and low temperature cycle shock

[0050] Test method: Place the moisture-changing color silicone between two pieces of glass, seal the four sides with packaging glue, and after curing, place the sample in a high and low temperature impact box and observe the color change time of the silicone.

[0051] Test instrument: Huitai Machinery HT-LC60-502.

[0052] Test conditions: -25℃(0.5h)~70℃(0.5h) 200 cycles.

[0053] 5. UV curing rate

[0054] Test method: The encapsulation adhesive is made into a thin sheet with a thickness of 0.25 microns.

[0055] Test conditions: 395nm, 100mj / cm 2

[0056] Testing instruments: UV light curing machine, Thermo Fisher infrared spectrometer IS50.

[0057] 6. Shear force

[0058] Test method: Use the encapsulation adhesive to bond glass and PS film, with a bonding area of ​​0.5 cm 2 , film thickness 0.25 microns.

[0059] Test instrument: ZQ-990LA-2

[0060] 7. Thermal curing rate

[0061] Test instrument: DZ-DSC300C

[0062] Test conditions: Place the sample at 25°C in a dark place

[0063] The test results are shown in Table 1.

[0064] Table 1. Performance test results of various embodiments and comparative examples

[0065]

[0066] The test results of Example 1 and Comparative Examples 1-2 show that the combination of modified dual-curing epoxy methacrylate and trimethylolpropane trimethacrylate has better reworkability than other trifunctional methacrylate diluents, and has no residue, which does not affect the continued use of the product.

[0067] The test results of Example 1 and Comparative Examples 3-4 show that: the amount of trimethylolpropane trimethacrylate is too small to meet the requirement of reworkability, and the amount of trimethylolpropane trimethacrylate is too large to meet the requirement of reworkability, but other properties are significantly reduced, and the service life of the overall product is reduced. The amount of trimethylolpropane trimethacrylate used in Example 1 is optimal.

[0068] The test results of Example 1 and Comparative Example 5 show that the addition of a toughening agent can avoid the generation of powder during the repair process.

[0069] The above description is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make corresponding adjustments and improvements without departing from the principles of the present invention. These adjustments and improvements should also be regarded as the scope of protection of the present invention.

Claims

1. A UV and heat dual-curing encapsulant for a reworkable display device, characterized in that: The packaging glue comprises the following raw materials in parts by weight: 30-40 parts of modified dual-curing epoxy methacrylate, 35-45 parts of methacrylate diluent, 2-3 parts of photoinitiator, 0.1-0.3 parts of defoamer, 1-2 parts of silane coupling agent, 10-15 parts of toughening agent and 5-8 parts of epoxy curing agent.

2. The UV and heat dual-curing encapsulant for a reworkable display device as claimed in claim 1, characterized in that: The modified dual-curing epoxy methacrylate is prepared as follows: 45-55 parts by weight of bisphenol F epoxy resin is added into a reactor, the temperature is raised to 75° C.-85° C. and stirred under nitrogen protection, 0.7-0.9 parts by weight of catalyst triethylbenzyl ammonium chloride and 20-30 parts by weight of methacrylic acid are added dropwise at a constant temperature, after the addition is completed, the temperature is raised to 115° C.-125° C. and the temperature is kept for reaction, the reaction is stopped when the acid value is less than 1 mgKOH / g, and the material is discharged hot to obtain the modified dual-curing epoxy methacrylate.

3. The UV and heat dual-curing encapsulant for a reworkable display device as claimed in claim 1, characterized in that: The methacrylate diluent is one or more of trimethylolpropane trimethacrylate, isobornyl methacrylate, isobornyl acrylate and polyethylene glycol (200) dimethacrylate.

4. The UV and heat dual-curing encapsulant for a reworkable display device according to claim 1, characterized in that: The photoinitiator is one or more of photoinitiator ITX, photoinitiator TMO, photoinitiator 819 and photoinitiator 184.

5. The UV and heat dual-curing encapsulant for a reworkable display device according to claim 1, characterized in that: The defoaming agent is one or more of BYK-016, YT-3300 and QM-2068.

6. The UV and heat dual-curing encapsulant for a reworkable display device according to claim 1, characterized in that: The toughening agent is one or more of MX-154, IB7774 and 402.

7. A method for preparing a UV and heat dual-curing encapsulant for a reworkable display device as claimed in any one of claims 1 to 6, characterized in that: The steps include: Step 1, add a photoinitiator to a methacrylate diluent, heat in a water bath at 60°C-70°C to dissolve and stir until clear and transparent, then add modified dual-curing epoxy methacrylate, defoamer, silane coupling agent and toughening agent, stir at a speed of 1000-1500 rpm for 30-50 minutes, and then cool to 15°C-20°C; Step 2: Add epoxy curing agent to the material obtained in step 1, stir at a speed of 300-400 rpm for 10-15 minutes, maintain the material temperature at 15°C-20°C during stirring, filter, vacuum degas, and can to obtain UV and heat dual-curing packaging glue for repairable display devices.

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