Adhesive, preparation method of adhesive, polaroid using adhesive and preparation method of polaroid
By preparing adhesives containing antistatic agents and crosslinking agents, the electrostatic problem of polarizers is solved, high antistatic performance and durability are achieved, circuit board failures are reduced, and the use effect of polarizers is improved.
Patent Information
- Application Number
- CN202510309045.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-08-22
AI Technical Summary
The solvent-based acrylate pressure-sensitive adhesive used in existing polarizers has poor anti-static properties, which is prone to static electricity, resulting in circuit board failure, weak adhesion, easy hydrolysis, and poor weather resistance.
Adhesives are prepared by radical polymerization by using a combination of universal acrylate monomers, functional monomers, diluents, modifiers, antistatic agents, initiators and chain transfer agents, and ionic antistatic agents and crosslinking agents are added to improve antistatic properties and crosslinking degree to form a tight mesh structure.
It provides adhesives with stable antistatic properties, high viscosity and durability, which reduces circuit board failures caused by electrostatic accumulation, improves the service life of the polarizer, and reduces panel losses.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of adhesives, and in particular to an adhesive and a preparation method thereof, a polarizer using the adhesive and a preparation method thereof. Background Art
[0002] As people's living standards continue to improve, LCD TVs, mobile phones, computer monitors, tablets, and in-car computers have become indispensable tools for consuming information. These devices are also where polarizers are most widely used. Polarizers are a key raw material for display panels: they account for approximately 10% of the cost of LCD panels, a high proportion. Without considering losses, LCD panels require two polarizers, while OLED panels require one. In 2021, the global market for polarizers for panels reached US$10.2 billion. In 2021, China accounted for over 60% of global TFT-LCD panel production capacity, and domestic demand for polarizers reached 360 million square meters. Taking all production lines into account, domestic demand for polarizers for LCD / OLED panels reached 440 million square meters per year in 2022. According to DSCC data, the penetration rate of polarizers in the panel (OLED+LCD) market is expected to increase from 9% in 2022 to 14% in 2025. Therefore, the trend toward larger TV screens and the continued rise in OLED penetration are expected to drive increases in both volume and price for polarizers.
[0003] The adhesive used in polarizers can directly affect the performance of the entire screen. The adhesive's refractive index, pH, and other factors can affect the screen's performance and durability. Adhesives with other colors or insufficient transparency can directly affect the polarizer's refractive index, optical properties, and visual effects. Non-uniformity in the adhesive liquid can directly affect coating performance and the final properties of the polarizer product, such as initial tack, sustained tack, and peel strength. Furthermore, electronic screens generate static electricity during use. When static electricity accumulates to a certain level, it can directly damage highly sensitive components and increase the likelihood of circuit board failure. Dust adsorbed on circuit boards can reduce component insulation resistance, affecting circuitry. The discharge of static electricity can generate radio waves, damaging components or even rendering them inoperable.
[0004] Polarizers currently on the market generally use solvent-based acrylic pressure-sensitive adhesives. These have poor antistatic properties, making them prone to static electricity during use. Furthermore, traditional solvent-based acrylic pressure-sensitive adhesives have weak adhesion and are easily hydrolyzed, resulting in a short lifespan and poor weather resistance. In recent years, during the development of polarizers, circuit board failures caused by static electricity from pressure-sensitive adhesives have become increasingly common. Summary of the Invention
[0005] Purpose: To overcome the deficiencies in the prior art, the present invention provides an adhesive for polarizers, a preparation method, and a polarizer using the adhesive, which has re-peelability and can reduce the generation and accumulation of static electricity during use.
[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:
[0007] In a first aspect, the present application provides an adhesive comprising: 80-92 parts by mass of general acrylate monomer, 14-16 parts by mass of functional monomer, 15-24 parts by mass of diluent, 0.16-0.32 parts by mass of modifier, 0.03 parts by mass of initiator, 0.01 parts by mass of chain transfer agent, 6-8 parts by mass of antistatic agent; The general acrylate monomer includes 60-70 parts by mass of acrylate hard monomer and 20-22 parts by mass of acrylate soft monomer.
[0008] In some embodiments, the general acrylate monomer is selected from one or more of methyl methacrylate, acrylonitrile, ethyl acrylate, butyl acrylate, and isooctyl acrylate.
[0009] In some embodiments, the functional monomer is selected from one or more of acrylamide, hydroxymethyl acrylamide, diacetone acrylamide, ethyl acetoacetate methacrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, and vinyl triisopropoxy silane.
[0010] In some embodiments, the antistatic agent is an ionic antistatic agent selected from one or more of alkyl sulfonates, sulfates, phosphoric acid derivatives, higher fatty acid salts, carboxylates, amine salts, quaternary ammonium salts, and alkyl amino acid salts.
[0011] Among them, the quaternary ammonium salt is preferably selected from one or more of bis(trifluoromethylsulfonyl)imide salt, hexadecyldimethylammonium chloride, methylbenzenedimethylammonium chloride, and trimethylammonium bromide.
[0012] This type of antistatic agent has strong solubility and easily combines with moisture in the air through hydrogen bonds to form a conductive path. It also has good compatibility with acrylates and can be evenly distributed in the adhesive. Adding this antistatic agent and dispersing it evenly throughout the adhesive can compensate for the loss of antistatic properties on the adhesive surface, maintaining a long-lasting antistatic effect.
[0013] In some embodiments, the modifier is selected from one or more of an isocyanate crosslinker, an epoxy crosslinker, a polyamine crosslinker, a silane coupling agent, tetraethyl orthosilicate, and p-toluenesulfonic acid. When the isocyanate crosslinker and the silane coupling agent are used together as the modifier, the mass ratio of the two is 3:1 to 4:1. Preferably, the isocyanate crosslinker and the silane coupling agent are used together as the modifier, and the mass ratio of the two is 3:1.
[0014] Adding a modifier can increase the degree of crosslinking in the adhesive, prompting monomers to bridge between macromolecular chains to form a crosslinked film. The crosslinkable groups or special functional groups contained in the crosslinker provide crosslinking sites for further crosslinking reactions, thereby improving polymer strength and viscosity. Through special crosslinking groups, the crosslinker can ensure the connection between the main chains of the prepolymer and between the main chain and the side chains, forming a tighter network structure through polymerization, thereby improving cohesive strength and weather resistance. By controlling the amount of crosslinker used, the crosslink density can be increased to achieve the purpose of enhancing cohesive strength. At the same time, silane coupling agents contain both inorganic- and organic-friendly groups. The silane alkoxy group can react with inorganic substances, while the organic group is reactive or compatible with organic substances, which can better treat the bonding layer between the inorganic and organic interfaces.
[0015] In some embodiments, the diluent is selected from one or more of xylene, toluene, ethyl acetate, methyl acetate, butyl acetate, and silicone oil.
[0016] In some embodiments, the initiator is a free radical initiator, including azo-containing initiators, organic peroxide initiators, and redox initiators.
[0017] Preferably, the initiator is selected from one or more of benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropyl perbenzoate, tert-butyl pervalerate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, dimethyl azobisisobutyrate, and mercaptoethanol.
[0018] In some embodiments, the chain transfer agent is one or more of trichloroethylene, mercaptoethanol, dodecyl mercaptan, water, and the like.
[0019] In a second aspect, the present application provides a method for preparing the adhesive as described in the first aspect, the method comprising: first adding a general acrylate monomer to a reaction vessel, then adding a mixture of a functional monomer, a diluent, a modifier and an antistatic agent, heating in a water bath to 55-85°C, and then gradually adding an initiator and a chain transfer agent, reacting for 5.5-6.5 hours to obtain the adhesive.
[0020] Preferably, during the preparation process, the water bath is heated to 80° C. and the reaction is carried out at a constant temperature for 6 hours.
[0021] In a third aspect, the present application provides a polarizer coated with the adhesive as described in the first aspect.
[0022] In a fourth aspect, the present application provides a method for preparing the polarizer according to the third aspect, using the adhesive according to the first aspect, the method comprising: The adhesive is applied to the upper and lower sides of the stretched PVA film, and the upper and lower layers are laminated with PET and TAC respectively to obtain a polarizer substrate; Applying the adhesive on the protective film and the release film, and laminating the upper and lower sides of the polarizer substrate to obtain a polarizer roll sample; The polarizer samples are striped, cut and edge-grinded.
[0023] Beneficial Effects: The polarizer adhesive provided by the present invention exhibits relatively stable antistatic properties, high holding force, durability, and removable properties. This addresses the issue of circuit board failures caused by static electricity accumulation, ensuring its application in electronic products. This reduces circuit board failures caused by static electricity accumulation and increases the product's lifespan. Furthermore, its excellent removable properties reduce panel wear during polarizer application, saving costs. DETAILED DESCRIPTION
[0024] The present invention will be further described below with reference to the examples.
[0025] In the following examples, the raw materials used are from:
[0026] Table 1 Sources of adhesive components Components Manufacturer Methacrylate monomer Shanghai MacLean Biochemical Technology Co., Ltd. Ethyl acrylate monomer Shanghai MacLean Biochemical Technology Co., Ltd. Vinyltriisopropoxysilane Shanghai MacLean Biochemical Technology Co., Ltd. Methyl acetate Xilong Science Co., Ltd. Benzoyl peroxide Xilong Science Co., Ltd. Mercaptoethanol Xilong Science Co., Ltd. Blocked isocyanate crosslinker Shanghai MacLean Biochemical Technology Co., Ltd. Vinyltrioxysilane coupling agent Shanghai MacLean Biochemical Technology Co., Ltd. Bis(trifluoromethanesulfonyl)imide Shanghai MacLean Biochemical Technology Co., Ltd.
[0027] Example 1:
[0028] This embodiment first provides an adhesive, comprising 80-92 parts by mass of a general acrylate monomer, 14-16 parts by mass of a functional monomer, 15-24 parts by mass of a diluent, 0.16-0.32 parts by mass of a modifier, 0.03 parts by mass of an initiator, 0.01 parts by mass of a chain transfer agent, and 6-8 parts by mass of an antistatic agent; The general acrylate monomer includes 60-70 parts by mass of acrylate hard monomer and 20-22 parts by mass of acrylate soft monomer.
[0029] Based on the above components, the adhesive is prepared as follows: first, add a general-purpose acrylate monomer to a three-necked flask, followed by the functional monomer, diluent, modifier, and antistatic agent. A stirring rod is placed in the center of the flask, one side opening is blocked with a rubber stopper with a thermometer to reduce evaporation, and the other side is connected to a spherical condenser. Heat in a water bath to 80°C, then gradually add the initiator and chain transfer agent using a syringe. The reaction is then continued at this constant temperature for 6 hours to obtain the adhesive.
[0030] Example 2:
[0031] This embodiment provides a specific adhesive component composition based on the first embodiment, wherein the acrylate hard monomer is methacrylate monomer, the acrylate soft monomer is ethyl acrylate monomer, the functional monomer is acrylamide, the diluent is methyl acetate, the initiator is azobisisobutyronitrile, the chain transfer agent is mercaptoethanol, and the modifiers are a blocked isocyanate crosslinking agent and a vinyltrioxysilane coupling agent; The components include:
[0032] Example 3:
[0033] This embodiment provides a specific adhesive component composition based on the first embodiment, wherein the acrylate hard monomer is methacrylate monomer, the acrylate soft monomer is ethyl acrylate monomer, the functional monomer is acrylamide, the diluent is methyl acetate, the initiator is benzoyl peroxide, the chain transfer agent is mercaptoethanol, and the modifiers are blocked isocyanate crosslinking agent and vinyltrioxysilane coupling agent; The components include:
[0034] Example 4:
[0035] This embodiment provides a specific adhesive component composition based on the first embodiment, wherein the acrylate hard monomer is methacrylate monomer, the acrylate soft monomer is ethyl acrylate monomer, the functional monomer is vinyl triisopropoxy silane, the diluent is methyl acetate, the initiator is benzoyl peroxide, the chain transfer agent is mercaptoethanol, and the modifiers are blocked isocyanate crosslinking agent and vinyl trioxy silane coupling agent; The components include:
[0036] Embodiment 5:
[0037] This embodiment provides a specific adhesive component composition based on the first embodiment, wherein the acrylate hard monomer is methacrylate monomer, the acrylate soft monomer is ethyl acrylate monomer, the functional monomer is vinyl triisopropoxy silane, the diluent is methyl acetate, the initiator is benzoyl peroxide, the chain transfer agent is mercaptoethanol, and the modifiers are blocked isocyanate crosslinking agent and vinyl trioxy silane coupling agent; The components include:
[0038] Example 6:
[0039] This embodiment provides a specific adhesive component composition based on the first embodiment, wherein the acrylate hard monomer is methacrylate monomer, the acrylate soft monomer is ethyl acrylate monomer, the functional monomer is vinyl triisopropoxy silane, the diluent is methyl acetate, the initiator is benzoyl peroxide, the chain transfer agent is mercaptoethanol, the modifier is a blocked isocyanate crosslinker and a vinyl trioxysilane coupling agent, and the antistatic agent is bis(trifluoromethylsulfonyl)imide salt. The components include:
[0040] Embodiment seven:
[0041] This embodiment provides a specific adhesive component composition based on the first embodiment, wherein the acrylate hard monomer is methacrylate monomer, the acrylate soft monomer is ethyl acrylate monomer, the functional monomer is vinyl triisopropoxy silane, the diluent is methyl acetate, the initiator is benzoyl peroxide, the chain transfer agent is mercaptoethanol, the modifier is a blocked isocyanate crosslinker and a vinyl trioxysilane coupling agent, and the antistatic agent is bis(trifluoromethylsulfonyl)imide salt. The components include:
[0042] Embodiment 8:
[0043] This embodiment provides a method for preparing a polarizer, using the adhesive described in any one of Embodiments 1 to 7, the method comprising: The adhesive is applied to the upper and lower sides of the stretched PVA film, and the upper and lower layers are laminated with PET and TAC respectively to obtain a polarizer substrate; Applying the adhesive on the protective film and the release film, and laminating the upper and lower sides of the polarizer substrate to obtain a polarizer roll sample; The polarizer samples are striped, cut and edge-grinded.
[0044] Embodiment 9:
[0045] Based on the components of Example 7, without the addition of an antistatic agent, this example prepared five adhesives using the same components but different ratios according to the method of Example 1. Five polarizer samples were also prepared using the method of Example 8. Performance tests were conducted on the five samples, with the exception of antistatic stability. The experimental results are shown in Table 2. The components of Sample 5 were identical to those of Example 7, except for the antistatic agent.
[0046] Performance testing methods include:
[0047] 1. Dimensional weathering change test
[0048] The prepared polarizers were cut into 230 mm x 130 mm dimensions and laminated to 250 mm x 150 mm ordinary soda glass using a cold laminator to simulate the polarizer-to-panel lamination process. The laminated samples were placed in a pressurized degassing machine at 5 kgf / cm² and 50°C for 30 minutes to remove small bubbles that could impair the adhesive-glass bond. The samples were then exposed to simulated environments of high temperature (80°C), high humidity (85°C, 95% RH), cold (-60°C), and thermal shock (-40°C to 80°C). The edges and corners of the polarizers were observed for obvious signs of bubbles, lifting, peeling, foaming, or adhesive cracking. The polarizers were also compared for dimensional changes in the simulated environments. Any signs of bubbles, lifting, peeling, foaming, or adhesive cracking were considered NG.
[0049] Among them, dimensional weather resistance change = dimensional change / size before change = (after change - before change) / size before change * 100%.
[0050] 2. Adhesion Test
[0051] Polarizers were cut into 25 mm x 150 mm samples and bonded to 50 mm x 150 mm glass using a 2 kg roller. Adhesion was tested under high temperature and high humidity conditions for 48 hours. Testing was performed at a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%.
[0052] 3. Re-peeling performance test
[0053] The prepared polarizer was cut to the size of a 21-inch panel and edge-grinded before being laminated to the 21-inch panel. The laminated sample was then placed in a pressurized degassing machine and subjected to 50 kgf / cm² at 50°C for 20 minutes. After 24 and 48 hours at room temperature, the polarizer was removed using a film peeler. The presence and amount of residual adhesive on the panel surface were checked, and the complete removal of the polarizer was compared. If the polarizer could be completely removed after 48 hours without leaving any residual adhesive on the surface, it was considered a pass; otherwise, it was considered a fail.
[0054] Table 2 Polarizer performance test results
[0055] Embodiment 10:
[0056] In this example, four adhesives were prepared based on the components of Sample 5, with the addition of varying amounts of antistatic agents. Four polarizer samples were also prepared using the method of Example 8. Performance tests, including antistatic stability, were conducted on the five samples. The experimental results are shown in Table 3. Sample 6 had the same components as Sample 5 in Example 9.
[0057] Performance testing methods include:
[0058] Cut the adhesive-coated polarizer into 8 cm x 8 cm pieces, remove the polarizer film, and place it on the measurement platform. With the concentric electrode probes of the high-impedance meter facing downward, press them firmly against the adhesive surface. Place a weight and measure the surface impedance of the pressure-sensitive adhesive at 100 V. The test should be conducted in an environment with a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%.
[0059] Polarizer samples were exposed to simulated environments (80°C, 80°C, 95% RH), and -60°C for a period of time. The changes in performance were observed to test the stability of the adhesive and the antistatic properties of the polarizers used. The overall impedance performance and stability under these simulated environments were evaluated. If the data differed significantly across different environments (overall percentage ≥ 40%), the overall impedance performance was considered NG.
[0060] Table 3 Performance test results of polarizers with antistatic agents added
[0061] In the above scheme, the surface impedance of the polarizer adhesive is measured to be 10 7 ~10 11 In the Ω range, when the adhesive does not contain antistatic agent, the impedance change is unstable. When the antistatic agent is 6 to 8 parts by mass, the surface impedance of the polarizer and polarizer adhesive is about 10 8 When the antistatic agent addition reaches 10 parts by weight, the impedance difference under different environments reaches 38%, and the impedance difference begins to increase. This shows that the critical concentration of antistatic agent is 6-8 parts by weight, which can form a dense and interconnected conductive network within the adhesive, quickly dissipating the static electricity originally accumulated in the adhesive and sharply reducing the resistivity to achieve the antistatic effect. Further addition may cause the solution to become oversaturated, leading to crystal precipitation and possibly affecting weather resistance and solution uniformity.
[0062] According to the data in Table 2 and Table 3, the present invention uses the antistatic agent and the comonomer to carry out a free radical polymerization reaction under the action of an initiator, a chain transfer agent, a diluent and a modifier compound, so that the obtained acrylic adhesive has good durability and antistatic properties. The resistance of the polarizer adhesive layer prepared using the acrylic adhesive can reach 10 8Ω, through experimental data, it can be found that the resistance data of the adhesive without adding antistatic agent varies greatly under different simulation conditions, which shows that the antistatic performance of traditional pressure-sensitive adhesives is unstable. Moreover, the adhesive can pass the rigorous simulation environment test. When the appropriate mass fraction of modifier is added, no bubbles will appear at the interface of the adhesive layer, and no floating, peeling, cracking, etc. will occur. At the same time, the prepared polarizer is cut into the required size to be bonded to the panel, which can ensure easy and complete tearing without leaving residual glue on the panel, ensuring the reusability of the panel. Therefore, the adhesive has excellent re-peeling performance, durability and antistatic performance. The above is only the preferred embodiment of the present disclosure / application. It should be pointed out that for ordinary technicians in this technical field, without departing from the technical principles of the present disclosure / application, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the scope of protection of the present disclosure / application.
Claims
1. An adhesive, characterized in that: Components include: 80-92 parts by mass of general acrylate monomer, 14-16 parts by mass of functional monomer, 15-24 parts by mass of diluent, 0.16-0.32 parts by mass of modifier, 0.03 parts by mass of initiator, 0.01 parts by mass of chain transfer agent, 6-8 parts by mass of antistatic agent; The general acrylate monomer includes 60-70 parts by mass of acrylate hard monomer and 20-22 parts by mass of acrylate soft monomer.
2. The adhesive according to claim 1, characterized in that The general acrylic acid ester monomer is selected from one or more of methyl methacrylate, acrylonitrile, ethyl acrylate, butyl acrylate, and isooctyl acrylate.
3. The adhesive according to claim 1, characterized in that The functional monomer is selected from one or more of acrylamide, hydroxymethyl acrylamide, diacetone acrylamide, ethyl acetoacetate methacrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, and vinyl triisopropoxy silane.
4. The adhesive according to claim 1, characterized in that The antistatic agent is an ionic antistatic agent, selected from one or more of alkyl sulfonates, sulfates, phosphoric acid derivatives, higher fatty acid salts, carboxylates, amine salts, quaternary ammonium salts, and alkyl amino acid salts.
5. The adhesive according to claim 1, characterized in that The modifier is selected from one or more of an isocyanate crosslinker, an epoxy crosslinker, a polyamine crosslinker, a silane coupling agent, tetraethyl orthosilicate, and p-toluenesulfonic acid. When the isocyanate crosslinker and the silane coupling agent are used as modifiers, the mass ratio of the two is 3:1 to 4:
1.
6. The adhesive according to claim 1, characterized in that The diluent is selected from one or more of xylene, toluene, ethyl acetate, methyl acetate, butyl acetate, and silicone oil.
7. The adhesive according to claim 1, characterized in that The initiator is a free radical initiator, including azo initiators, organic peroxide initiators, and redox initiators; And / or, the chain transfer agent is selected from one or more of trichloroethylene, mercaptoethanol, dodecyl mercaptan, and water.
8. A method for preparing the adhesive according to any one of claims 1 to 7, characterized in that: The method comprises: firstly adding a general acrylate monomer into a reaction container, then adding a mixture of a functional monomer, a diluent, a modifier and an antistatic agent, heating in a water bath to 55-85° C., then gradually adding an initiator and a chain transfer agent, and reacting for 5.5-6.5 hours to obtain the product.
9. A polarizer, characterized in that: The polarizer is coated with the adhesive according to any one of claims 1 to 7.
10. A method for preparing a polarizer, characterized in that: Using the adhesive according to any one of claims 1 to 7, the method comprises: The adhesive is applied to the upper and lower sides of the stretched PVA film, and the upper and lower layers are laminated with PET and TAC respectively to obtain a polarizer substrate; Applying the adhesive on the protective film and the release film, and laminating the upper and lower sides of the polarizer substrate to obtain a polarizer roll sample; The polarizer samples are striped, cut and edge-grinded.