Multiband absorption optical cement applied to full lamination and preparation method thereof

Abstract

The invention relates to the technical field of optical cement, in particular to full-lamination multiband absorption optical cement and a preparation method thereof. The optical adhesive adopts the polypropylene carbonate modified cyanoacrylate which has better flexibility and impact resistance, the caffeic acid modified lignin ester derivative is added, the transparency of the adhesive is kept, meanwhile, the adhesive is endowed with double functions of oxidation resistance and ultraviolet absorption, and the optical adhesive is prepared through a coprecipitation method. Triazine and salicylate ultraviolet absorbers are inserted into a layered Zn3Al2 (OH) 8 two-dimensional bimetallic nanosheet to prepare a novel ultraviolet shielding material, so that the light aging resistance of an adhesive layer is improved, and the adhesive layer is endowed with multiband light absorption capacity. The optical adhesive can adapt to electronic products with different sizes, and has the advantages of full lamination, high light transmittance and good light aging resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical adhesives, and particularly relates to a multi-band absorption optical adhesive for full lamination and a preparation method thereof. Background Art

[0002] An optical adhesive is a high light transmittance adhesive product, which is applied to the bonding of transparent optical materials, such as electronic optical components like touch screens, displays, ITO films, glass, acrylic, PC, etc. The UV optical adhesive that can be used for displays needs to have strong adhesiveness, high light transmittance, and high impact resistance.

[0003] Optical adhesives can be divided into liquid optical adhesives and solid optical adhesives. Liquid optical adhesives have high light transmittance, good bonding strength, small curing shrinkage rate, yellowing resistance, and are used for the lamination of small-sized products, but they are expensive and have high lamination costs. In contrast, solid optical adhesives have more excellent optical properties. The refractive index can be adjusted between 1.40 and 1.52 according to different glue components and glue layer thicknesses. They have good stability under the influence of temperature and external light, are not easily deteriorated, have high safety, and are also suitable for the lamination of large-sized products without the need for overflow glue treatment, and have higher cost performance.

[0004] Multi-band absorption optical adhesives have attracted much attention because they can selectively adjust in light of different bands. They have a wide spectral applicability, can cover bands from ultraviolet to near-infrared, etc., adapt to various different optical systems, can increase the transmission distance of optical signals, thereby improving imaging quality, reducing image blurring, etc., and can be applied to fields such as solar cells, optical fiber communication, laser technology, and photoelectric imaging.

[0005] Full lamination technology has been widely used in the fields of optical display and sensors, especially in high-end displays, optical sensors, and intelligent devices. The performance of the optical adhesive used for full lamination technology can directly determine the optical effect, stability, and service life of the device. Chinese Patent with the authorization announcement number CN 111171781 B discloses a full lamination photocurable silicone liquid optical adhesive. This liquid optical adhesive has good chemical compatibility and can achieve the technical effect of seamless lamination; however, all liquid adhesives have the problem of overflow glue, so during lamination, it is also necessary to deal with the overflow glue, and there will also be problems such as incomplete curing and bubbles, and the overall cost is relatively high. Chinese Patent Application with the application number CN 115537125 A discloses a scratch-resistant optical adhesive, which improves the external scratch-resistant function of the optical adhesive by adding a scratch-resistant coating. However, only hindered amine agents or hexamethylphosphoric triamide ultraviolet absorbers are added to its optical adhesive, and its regulation of light in different bands is poor, its adaptability to the spectrum is low, and its application range and service life are both limited.

[0006] Based on the above problems, providing a multi-band absorption optical adhesive applicable to full lamination and a preparation method thereof is still an urgent problem to be solved in this field. Summary of the Invention

[0007] The present invention aims to provide a multi-band absorbing optical adhesive for full lamination and a preparation method thereof. The optical adhesive uses poly(propylene carbonate) modified cyanoacrylate, which has good transparency, flexibility and impact resistance. By adding caffeic acid modified lignin ester derivatives, while maintaining the good transparency of the adhesive, the pressure-sensitive adhesive is endowed with the dual functions of antioxidant and ultraviolet absorption. Through the coprecipitation method, triazine-based and salicylate-based ultraviolet absorbers are inserted into the layered Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets to prepare a novel ultraviolet nanoshielding material, so as to improve the light aging resistance of the adhesive and endow the pressure-sensitive adhesive with the ability to absorb multi-band light. The optical adhesive is applied to the field of full lamination technology of display screens, can adapt to display screens of different sizes, and has the properties of full lamination, high light transmittance and good light aging resistance.

[0008] To achieve the above object, the present invention provides a multi-band absorbing optical adhesive for full lamination. The optical adhesive is prepared from poly(propylene carbonate) modified cyanoacrylate, adding caffeic acid modified lignin ester derivatives and layered Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets containing ultraviolet absorbers.

[0009] To achieve the above object, the present invention also provides a preparation method of a multi-band absorbing optical adhesive for full lamination, including:

[0010] S1. Poly(propylene carbonate) is dispersed in cyclopentanone and reacted with cyanoacrylate monomers to obtain modified cyanoacrylate;

[0011] S2. Wood fibers are dispersed in a good solvent and reacted with an esterifying agent and a catalyst to obtain lignin ester derivatives, and then reacted with caffeic acid and a photoinitiator to obtain caffeic acid modified lignin ester derivatives;

[0012] Step S3. A zinc salt and an aluminum salt are mixed, a solvent is added, and the mixture is reacted to obtain a mixture. 2-Methylimidazole is dissolved in an alcohol solvent and reacted with the mixture to obtain Zn 3 Al 2 (OH) 8 crude two-dimensional bimetallic nanosheets, which are washed and freeze-dried to obtain Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets;

[0013] S4. Dissolve salicylic acid 2-ethylhexyl ester and 2,4,6-tris(2'-hydroxy-4'-n-butoxyphenyl) in absolute ethanol, add an ionic solution to obtain solution A, Zn 3 Al 2 (OH) 8 Disperse the two-dimensional bimetallic nanosheets in deionized water to obtain solution B. Add solution A to solution B, react to obtain a crude product, wash and dry it to obtain Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets;

[0014] S5. Add the caffeic acid-modified lignin ester derivative, Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets with ultraviolet absorber inserted and a thickening agent into the modified cyanoacrylate, stir to obtain a multi-band absorption optical sol, uniformly coat it on a glass plate, wait for curing to obtain a multi-band absorption optical glue.

[0015] Preferably, in step S1, the reaction temperature of poly(propylene carbonate) and cyanoacrylate monomer is 100-130 °C, and the reaction time is 2-3 h.

[0016] Preferably, in step S2, the reaction temperature of wood fiber with an esterifying agent and a catalyst is 90-120 °C, and the reaction time is 2-5 h. The reaction temperature of the lignin ester derivative with caffeic acid and a photoinitiator is 90-120 °C, and the reaction time is 4-6 h.

[0017] Preferably, in step S3, the reaction temperature of zinc salt and aluminum salt is 25-30 °C, and the reaction time is 2-3 h. The reaction temperature of 2-methylimidazole and the mixture is 25-30 °C, and the reaction time is 3-4 h. The washing solvent is methanol and deionized water, and the freeze-drying temperature is -20 to -40 °C, and the freeze-drying time is 45-48 h.

[0018] Preferably, in step S4, the reaction temperature of solution A and solution B is 25-30 °C, and the reaction time is 20-24 h. The drying temperature is 50-60 °C, and the drying time is 10-12 h. The washing reagent is deionized water.

[0019] Preferably, in step S5, the stirring temperature is 25-30 °C, and the stirring time is 3-4 h.

[0020] Preferably, the average molecular weight of the poly(propylene carbonate) is 89000-98000 g / mol.

[0021] Preferably, the purity of the cyclopentanone is ≥99%; the mass ratio of the cyanoacrylate monomer, poly(propylene carbonate), and cyclopentanone is 1:(0.025 - 0.05):(4 - 5).

[0022] Preferably, the good solvent is any one or more of dimethyl sulfoxide, cyclohexane, toluene, ionic liquid, and deep eutectic solvent.

[0023] Preferably, the lignocellulose is any one or more of poplar lignocellulose, pine lignocellulose, fir lignocellulose, locust tree lignocellulose, and lignocellulose powder; the esterifying reagent is any one or more of 2-bromo-2-methylpropanoyl bromide and 2-bromopropanoyl bromide.

[0024] Preferably, the catalyst is any one or more of potassium carbonate, sodium bicarbonate, sodium hydroxide, triethylamine, and 4-dimethylaminopyridine.

[0025] Preferably, the photoinitiator is any one or more of benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin butyl ether.

[0026] Preferably, the purity of the caffeic acid is ≥98.0%.

[0027] Preferably, the mass ratio of the lignocellulose, good solvent, esterifying reagent, catalyst, caffeic acid, and photoinitiator is 1:(4 - 5):(1 - 3):(0.005 - 0.05):(0.01 - 0.02):(0.005 - 0.01).

[0028] Preferably, the zinc salt is any one or more of zinc sulfate, zinc chloride, and zinc nitrate.

[0029] Preferably, the aluminum salt is any one or more of aluminum sulfate, aluminum chloride, and aluminum nitrate.

[0030] Preferably, the solvent is a mixed solution of methanol and water with a volume ratio of 1:1.

[0031] Preferably, the mass ratio of the zinc salt, aluminum salt, and solvent is 1:(1.5 - 2):(10 - 15).

[0032] Preferably, the alcohol solvent is any one or more of methanol, ethanol, and isopropanol.

[0033] Preferably, the mass ratio of 2-methylimidazole and the alcohol solvent is 1:(10 - 15).

[0034] Preferably, the volume ratio of the alcohol solution of 2-methylimidazole and the mixture is 1:1.

[0035] Preferably, the ionic solution is any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0036] The mass ratio of salicylic acid 2-ethylhexyl ester, 2,4,6-tris(2'-hydroxy-4'-n-butoxyphenyl), absolute ethanol, and ionic solution is 1:(1-1.5):(4-5):(1.5-2).

[0037] Preferably, the 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheet and deionized water have a mass ratio of 1:(4-5).

[0038] Preferably, the mass ratio of solution A and solution B is 1:(5-6).

[0039] Preferably, the mass ratio of poly(propylene carbonate) modified cyanoacrylate, caffeic acid modified lignin ester derivative, Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheet and thickener is 1:(0.2-0.5):(0.1-0.5):(0.5-0.7).

[0040] Preferably, the thickener is any one or more of polyacrylic acid, carboxymethyl cellulose ether, and polyacrylamide.

[0041] Preferably, the thickness of the multi-band absorption optical adhesive is 25-250 μm.

[0042] (1) In the present invention, poly(propylene carbonate) is used to modify cyanoacrylate to prepare an optical adhesive, which can increase its ductility, improve the processing performance, impact resistance, and flexibility of the original cyanoacrylate, and at the same time maintain transparency. Poly(propylene carbonate) is a plastic with excellent toughness. The molecular structure contains the rigidity of polycarbonate and the flexibility of polyester, making it have higher impact strength and flexural modulus, thus improving the fracture resistance of the material. The glass transition temperature of poly(propylene carbonate) is usually higher than that of cyanoacrylate, which means that poly(propylene carbonate) can still maintain good elasticity at higher temperatures, while cyanoacrylate becomes brittle after reaching its glass transition temperature. Introducing poly(propylene carbonate) into cyanoacrylate, crosslinking can significantly increase the crosslinking density of cyanoacrylate and the interaction between molecular chains. Poly(propylene carbonate) is dispersed in the rigid molecular network of cyanoacrylate, improving the overall flexibility and toughness.

[0043] (2) To achieve the multi-band absorption characteristics of the optical adhesive, the present invention separately uses caffeic acid modified lignin ester derivative and layered Zn 3 Al 2 (OH) 8Two-dimensional bimetallic nanosheets. The addition of caffeic acid can functionalize lignin ester derivatives. Furthermore, the film exhibits strong free radical scavenging activity, establishing an efficient dual function of antioxidant and ultraviolet absorption without loss of transparency. As an ultraviolet absorber, its transmittance is less than 0% in the UVB (275 - 320 nm) and UVC (200 - 275 nm) ranges, and about 15% in the UVA (320 - 420 nm) range; adding a layered Zn 3 Al 2 (OH) 8 Two-dimensional bimetallic nanosheets endow the optical adhesive with the ability to absorb various electromagnetic waves. The multi-layer hierarchical structure microwave absorbing material is composed of superposition of layer structures with different parameters, including intermediate layers, void layers, etc. The unique structure endows it with characteristics such as low density, high specific surface area, and void space. The ultraviolet absorber can be loaded on the nanosheets by co-precipitation, significantly increasing its contact area with ultraviolet rays, thereby improving the absorption efficiency of the ultraviolet absorber. The intermediate layer of the layered structure is filled with negatively charged anions, which can quickly transfer to the ultraviolet absorber molecules, making it easier for the absorber molecules to be excited and absorb ultraviolet rays. Description of the Drawings

[0044] Figure 1 It is a preparation process of a multi-band absorbing optical adhesive for full lamination.

[0045] Figure 2 It is a schematic structural diagram of the application of a multi-band absorbing optical adhesive for full lamination in an OLED display screen.

[0046] Figure 3 It is a schematic structural diagram of caffeic acid-modified lignin ester derivatives in the optical adhesive.

[0047] Figure 4 It is Zn in the optical adhesive 3 Al 2 (OH) 8 Schematic structural diagram of two-dimensional bimetallic nanosheets.

[0048] Figure 5 It is a comparison chart of the light transmittance of the optical adhesives prepared in Examples 1 - 3 and Comparative Examples 1 - 3 before and after light aging.

[0049] Figure 6 It is a comparison chart of the haze of the optical adhesives prepared in Examples 1 - 3 and Comparative Examples 1 - 3 before and after light aging.

[0050] Figure 7 It is a comparison chart of the b value of the optical adhesives prepared in Examples 1 - 3 and Comparative Examples 1 - 3 before and after light aging.

[0051] Figure 8Comparison chart of the bonding strength of the optical adhesives prepared in Examples 1 to 3 and Comparative Examples 1 to 3 before and after photoaging.

[0052] Meanings of the reference numerals: a, glass cover plate; b, optical adhesive; c, encapsulation glass; d, organic light-emitting diode; e, glass TFT backplane; f, heat sink; g, backplane. Detailed implementation manners

[0053] The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

[0054] Example 1

[0055] As Figure 1 shown, a preparation method of a multi-band absorption optical adhesive for full lamination includes the following steps:

[0056] (1) Accurately weigh 0.13 g of poly(propylene carbonate) and disperse it in 20 - 25 mL of cyclopentanone, ultrasonically treat for 80 - 90 min, add 5 g of cyanoacrylate monomer, and react at 100 - 130 °C for 2 - 3 h to obtain poly(propylene carbonate) modified cyanoacrylate.

[0057] (2) Disperse 5 g of wood fiber in 25 - 30 mL of cyclohexane, ultrasonically treat for 5 - 10 min, successively add 5 g of 2-bromo-2-methylpropionyl bromide and 0.025 g of sodium hydroxide, react at 90 - 120 °C for 2 - 5 h to obtain a lignin ester derivative, add 0.5 g of caffeic acid and 0.025 g of benzoin dimethyl ether, and react at 90 - 120 °C for 4 - 6 h to obtain a caffeic acid modified lignin ester derivative, the structure is as Figure 3 shown.

[0058] (3) Accurately weigh 5 g of zinc salt and 7.5 g of aluminum salt and mix them, dissolve in a 40 - 60 mL mixed solution of methanol:water at a ratio of 1:1, react at 25 - 30 °C for 2 - 3 h to obtain a mixture; accurately weigh 5 g of 2-methylimidazole and dissolve it in 40 - 60 mL of ethanol, add all of it to the mixture, react at 25 - 30 °C for 3 - 4 h, centrifuge, wash the solid with methanol and deionized water respectively, and freeze-dry at -20 - -40 °C for 45 - 48 h to obtain Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets.

[0059] (4) Accurately weigh 1 g of 2-ethylhexyl salicylate and 1 g of 2,4,6-tris(2'-hydroxy-4'-n-butoxyphenyl), dissolve them in 4 - 5 mL of absolute ethanol, add 1.5 g of sodium carbonate to obtain solution A; add 10 g of Zn 3 Al 2 (OH)8 Disperse two-dimensional bimetallic nanosheets in 40 - 50 mL of deionized water to obtain solution B; add 5 mL of solution A dropwise to 25 - 30 mL of solution B, react at 25 - 30 °C for 20 - 24 h, wash the solid with deionized water, and dry it at 50 - 60 °C for 10 - 12 h to obtain Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets with a structure as shown in Figure 4 shown.

[0060] (5) Add 2 g of caffeic acid-modified lignin ester derivative and 1 g of Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets to 10 g of poly(propylene carbonate)-modified cyanoacrylate, add 5 g of polyacrylic acid, and stir at 25 - 30 °C for 3 - 4 h to obtain a multi-band absorbing optical sol.

[0061] (6) Use a spin coater to uniformly coat the multi-band absorbing optical sol on a smooth and dust-free glass substrate with a thickness of 25 - 250 μm, and wait for curing to obtain a multi-band absorbing optical adhesive.

[0062] Example 2

[0063] As shown in Figure 1 shown, a preparation method of a multi-band absorbing optical adhesive for full lamination includes the following steps:

[0064] (1) Accurately weigh 0.3 g of poly(propylene carbonate) and disperse it in 20 - 25 mL of cyclopentanone, ultrasonically treat for 80 - 90 min, add 5 g of cyanoacrylate monomer, and react at 100 - 130 °C for 2 - 3 h to obtain poly(propylene carbonate)-modified cyanoacrylate.

[0065] (2) Disperse 5 g of wood fiber in 25 - 30 mL of cyclohexane, sequentially add 10 g of 2-bromo-2-methylpropionyl bromide and 0.05 g of sodium hydroxide, react at 90 - 120 °C for 2 - 5 h to obtain a lignin ester derivative, add 0.75 g of caffeic acid and 0.05 g of benzoin dimethyl ether, and react at 90 - 120 °C for 4 - 6 h to obtain a caffeic acid-modified lignin ester derivative with a structure as shown in Figure 3 shown.

[0066] (3) Accurately weigh 5 g of zinc salt and 10 g of aluminum salt, mix them, dissolve in a 40 - 60 mL mixed solution of methanol:water with a ratio of 1:1, react at 25 - 30 °C for 2 - 3 h to obtain a mixture; accurately weigh 5 g of 2 - methylimidazole and dissolve it in 40 - 60 mL of ethanol, add all of it to the mixture, react at 25 - 30 °C for 3 - 4 h, centrifuge, wash the solid with methanol and deionized water respectively, and freeze - dry at - 20 - - 40 °C for 45 - 48 h to obtain Zn 3 Al 2 (OH) 8 two - dimensional bimetallic nanosheets.

[0067] (4) Accurately weigh 1 g of 2 - ethylhexyl salicylate and 1.5 g of 2,4,6 - tris(2'-hydroxy - 4'-n - butoxyphenyl) and dissolve them in 4 - 5 mL of absolute ethanol, add 2 g of sodium carbonate to obtain solution A; disperse 10 g of Zn 3 Al 2 (OH) 8 two - dimensional bimetallic nanosheets in 40 - 50 mL of deionized water to obtain solution B; add 5 mL of solution A dropwise to 25 - 30 mL of solution B, react at 25 - 30 °C for 20 - 24 h, wash the solid with deionized water, and dry at 50 - 60 °C for 10 - 12 h to obtain Zn 3 Al 2 (OH) 8 two - dimensional bimetallic nanosheets with ultraviolet absorber inserted, the structure is as Figure 4 shown.

[0068] (5) Add 3.5 g of caffeic acid - modified lignin ester derivative and 3 g of Zn 3 Al 2 (OH) 8 two - dimensional bimetallic nanosheets with ultraviolet absorber inserted into 10 g of poly(propylene carbonate) - modified cyanoacrylate, add 6 g of polyacrylic acid, stir at 25 - 30 °C for 3 - 4 h to obtain a multi - band absorbing optical sol.

[0069] (6) Use a spin coater to uniformly coat the multi - band absorbing optical sol on a smooth and dust - free glass substrate with a thickness of 25 - 250 μm, wait for curing to obtain a multi - band absorbing optical adhesive.

[0070] Example 3

[0071] As Figure 1 shown, a preparation method of a multi - band absorbing optical adhesive for full lamination includes the following steps:

[0072] (1) Weigh accurately 0.3 g of poly(propylene carbonate) and disperse it in 20 - 25 mL of cyclopentanone. Add 5 g of cyanoacrylate monomer and react at 100 - 130 °C for 2 - 3 h to obtain poly(propylene carbonate) modified cyanoacrylate.

[0073] (2) Disperse 5 g of lignocellulose in 25 - 30 mL of cyclohexane. Add 15 g of 2-bromo-2-methylpropionyl bromide and 0.05 g of sodium hydroxide successively and react at 90 - 120 °C for 2 - 5 h to obtain lignin ester derivatives. Add 1 g of caffeic acid and 0.05 g of benzoin dimethyl ether and react at 90 - 120 °C for 4 - 6 h to obtain caffeic acid modified lignin ester derivatives, the structure is as Figure 3 shown.

[0074] (3) Weigh accurately 5 g of zinc salt and 10 g of aluminum salt and mix them. Dissolve them in 40 - 60 mL of a mixed solvent of methanol:water = 1:1 and react at 25 - 30 °C for 2 - 3 h to obtain a mixture. Weigh accurately 5 g of 2-methylimidazole and dissolve it in 40 - 60 mL of ethanol. Add all of it to the mixture and react at 25 - 30 °C for 3 - 4 h. Centrifuge and wash the solid with methanol and deionized water respectively, and freeze-dry at -20 - -40 °C for 45 - 48 h to obtain Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets.

[0075] (4) Weigh accurately 1 g of 2-ethylhexyl salicylate and 1.5 g of 2,4,6-tris(2'-hydroxy-4'-n-butoxyphenyl) and dissolve them in 4 - 5 mL of absolute ethanol. Add 2 g of sodium carbonate to obtain solution A. Disperse 10 g of Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets in 40 - 50 mL of deionized water to obtain solution B. Drop 5 mL of solution A into 25 - 30 mL of solution B and react at 25 - 30 °C for 20 - 24 h. Wash the solid with deionized water and dry at 50 - 60 °C for 10 - 12 h to obtain Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets inserted with ultraviolet absorber, the structure is as Figure 4 shown.

[0076] (5) Add 5 g of caffeic acid modified lignin ester derivatives and 5 g of Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets inserted with ultraviolet absorber into 10 g of poly(propylene carbonate) modified cyanoacrylate. Add 7 g of polyacrylic acid and stir at room temperature for 3 - 4 h to obtain a multi-band absorption optical sol.

[0077] (6) Use a spin coater to uniformly coat the multi-band absorption optical sol on a smooth and dust-free glass substrate with a thickness of 25 - 250 μm, and wait for curing to obtain the multi-band absorption optical glue.

[0078] Comparative Example 1

[0079] As Figure 1 shown, a preparation method of a multi-band absorption optical glue for full lamination, which is different from Example 2 in that poly(propylene carbonate) is not added in step (1).

[0080] Comparative Example 2

[0081] As Figure 1 shown, a preparation method of a multi-band absorption optical glue for full lamination, which is different from Example 2 in that caffeic acid is not added in step (2).

[0082] Comparative Example 3

[0083] As Figure 1 shown, a preparation method of a multi-band absorption optical glue for full lamination, which is different from Example 2 in that Zn 3 Al 2 (OH) 8 two-dimensional bimetallic nanosheets are not added.

[0084] Stability test: Measure the initial b value (ASTM D1925 / C2) of the optical glues prepared in Examples 1 - 3 and Comparative Examples 1 - 3, the b value (ASTM D1925 / C2) after being placed in an 80°C environment for 500 h and cycled 500 times at a temperature of -40°C to 80°C, and detect the anti-alternating damp heat (GB / T 2423.4 - 1993), salt spray resistance (GB / T 2423.17 - 1993), and high temperature and high humidity aging performance (GB / T 32368 - 2015) of the optical glues.

[0085] Bonding performance test: Measure the bonding strength (T / Cl 144 - 2023) of the optical glues prepared in Examples 1 - 3 and Comparative Examples 1 - 3 at room temperature, and the bonding strength (T / Cl 144 - 2023) of the optical glues after being placed in an 80°C environment for 500 h and cycled 500 times at a temperature of -40°C to 80°C, respectively.

[0086] Photoaging performance test: Use a multi-band ultraviolet aging test chamber for testing, and test the photoaging resistance of the optical glues prepared in Examples 1 - 3 and Comparative Examples 1 - 3. Set the irradiation intensity of ultraviolet light to 100 mW / cm 2, the aging time is 500 h, and the color, initial b value (ASTM D1925 / C2), haze, and light transmittance (ASTM D 1003-2013), and adhesion strength (T / Cl 144-2023) of the test samples after light aging are tested.

[0087] Figures 6 - 8 In the UVC band, the wavelength is 200 - 275 nm, in the UVB band, the wavelength is 275 - 320 nm, and in the UVA band, the wavelength is 320 - 420 nm.

[0088] According to Figure 5 As shown, after the optical adhesives prepared in Examples 1 - 3 are irradiated with UV light in three bands for 500 h, the light transmittance is above 97%, and a high light transmittance can be maintained. After the optical adhesives prepared in Comparative Examples 1 - 3 are irradiated for 500 h, the light transmittance decreases to varying degrees. The degree of decrease in the light transmittance of Comparative Example 1 is higher than that of Examples 1 - 3, but lower than that of Comparative Examples 2 and 3. The optical adhesive prepared in Comparative Example 2 has the most significant decrease in light transmittance under UVC and UVB band light irradiation, and the optical adhesive prepared in Comparative Example 3 has the most obvious decrease in light transmittance under UVA band light irradiation.

[0089] According to Figure 6 As shown, after the optical adhesives prepared in Examples 1 - 3 are irradiated with UV light in three bands for 500 h, the haze is below 0.5%, and a high transparency can be maintained. After the optical adhesives prepared in Comparative Examples 1 - 3 are irradiated for 500 h, the haze increases to varying degrees. The increase in haze of the optical adhesive prepared in Comparative Example 1 under irradiation in three bands is higher than that of Examples 1 - 3, but significantly lower than that of Comparative Examples 2 and 3. The optical adhesive prepared in Comparative Example 2 has the largest increase in haze under UVC and UVB band light irradiation, and the optical adhesive prepared in Comparative Example 3 has the largest increase in haze under UVA band light irradiation.

[0090] According to Figure 7 As shown, after the optical adhesives prepared in Examples 1 - 3 are irradiated with UV light in three bands for 500 h, the b value is below 0.7, and it is colorless and transparent to the naked eye. After the optical adhesives prepared in Comparative Examples 1 - 3 are irradiated for 500 h, the b value increases to varying degrees. The increase in the b value of Comparative Example 1 is higher than that of Examples 1 - 3, but lower than that of Comparative Examples 2 and 3. The optical adhesive prepared in Comparative Example 2 has the most significant increase in the b value under UVC and UVB band light irradiation, and the optical adhesive prepared in Comparative Example 3 has a significant increase in the b value under UVA band light irradiation.

[0091] Based on the above analysis, the main reason is that in Comparative Example 1, both caffeic acid is used to modify lignin ester derivatives and Zn 3 Al 2 (OH) 8The absorption efficiency of the two-dimensional bimetallic nanosheet ultraviolet absorber is poor due to the lack of copolymerization of poly(propylene carbonate) and cyanoacrylate, resulting in poor overall stability and insufficient ability to resist ultraviolet light. In Comparative Example 2, caffeic acid was not used to modify the lignin ester derivative, and the surface lacked activated functional groups, resulting in weak ultraviolet light absorption ability in the UVC and UVB bands. In Comparative Example 3, Zn 3 Al 2 (OH) 8 The two-dimensional bimetallic nanosheet has the weakest ability to absorb ultraviolet light in the UVA band. Ultraviolet light in this band has strong penetration and the strongest ability to damage the optical adhesive. In Comparative Example 3, only an ultraviolet absorber was added to the optical adhesive. Under continuous UVA light illumination, the absorber will degrade due to chemical reactions such as oxidation and thermal decomposition, and its efficiency and absorption ability will gradually decrease.

[0092] According to Figure 8 As shown, after 500 h of UV light irradiation in the three bands, the bonding strength of the optical adhesives prepared in Examples 1 to 3 was relatively stable, remaining above 6 N / mm. The bonding strength of the optical adhesives prepared in Comparative Examples 2 and 3 decreased to varying degrees, and the bonding strength of the optical adhesive prepared in Comparative Example 1 decreased most significantly. Since the poly(propylene carbonate) and cyanoacrylate copolymer was not added to the optical adhesive prepared in Comparative Example 1, the flexibility and durability of cyanoacrylate are poor, and it may age, degrade and become brittle under conditions such as long-term light and high temperature, resulting in a decrease in the adhesive performance. The addition of poly(propylene carbonate) can improve its impact resistance, ductility, flexibility and bonding strength while maintaining the transparency of the colloid, and improve the service life of the adhesive.

[0093] According to the data in Table 1, the b values of the multi-band absorption optical adhesives prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were all around 0.3 at the initial stage, with little difference. After 500 thermal cycling between high temperature and cold, the optical adhesives prepared in Examples 1 to 3 and Comparative Examples 2 and 3 showed little difference compared with the initial state, while the b value of the optical adhesive prepared in Comparative Example 1 increased significantly. In the alternating damp heat resistance test, bubbles appeared between the optical adhesive prepared in Comparative Example 1 and the substrate. In the salt spray resistance test, the adhesive layer turned yellow, and bubbles appeared in the high temperature and high humidity aging test, and then delamination occurred with the substrate. In summary, the optical adhesive prepared in Comparative Example 1 does not have good heat resistance, weather resistance, durability, adaptability and corrosion resistance.

[0094] Table 1 Stability performance parameters of optical adhesives

[0095]

[0096]

[0097] As shown in the data of Table 2, the multi-band absorption optical adhesives prepared in Examples 1 to 3 and Comparative Examples 1 to 3 all had good bonding strength in the initial stage. After high-temperature treatment, the bonding strength of Comparative Example 1 decreased significantly. After 500 cycles of high-temperature and low-temperature cycling, the bonding strength of Comparative Example 1 decreased significantly. This is mainly because poly(propylene carbonate) was not added to the optical adhesive prepared in Comparative Example 1. The weather resistance, adhesiveness, and mechanical properties of the poly(propylene carbonate) and cyanoacrylate copolymer are all better than those of cyanoacrylate. Because the polymer chain of propylene carbonate can fill the microscopic pores of cyanoacrylate, enhance the interfacial bonding, and improve the mechanical strength of the bonded parts. The long chain segment of poly(propylene carbonate) can also play a role of physical bridging in the cross-linked network of cyanoacrylate, improving the toughness of the composite material.

[0098] Table 2 Adhesiveness Parameters of Optical Adhesive

[0099]

[0100] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a multi-band absorption optical adhesive for full bonding, characterized in that: include: Step S1, polypropylene carbonate is dispersed in cyclopentanone and reacted with cyanoacrylate monomer to obtain modified cyanoacrylate; Step S2, dispersing wood fibers in a good solvent, reacting with an esterifying agent and a catalyst to obtain lignin ester derivatives, adding caffeic acid and a photoinitiator, and reacting to obtain caffeic acid-modified lignin ester derivatives; Step S3, zinc salt and aluminum salt are mixed, a solvent is added, and a mixture is obtained by reaction, 2-methylimidazole is dissolved in an alcohol solvent, and the mixture is reacted to obtain a crude product of Zn3Al2(OH)8 two-dimensional bimetallic nanosheets, which is washed and freeze-dried to obtain Zn3Al2(OH)8 two-dimensional bimetallic nanosheets; Step S4, 2-ethylhexyl salicylate and 2,4,6-tris(2'-hydroxy-4'-n-butoxyphenyl) are dissolved in anhydrous ethanol, and an ion solution is added to obtain solution A, Zn3Al2(OH)8 two-dimensional bimetallic nanosheets are dispersed in deionized water to obtain solution B, solution A and solution B are mixed, reacted to obtain a crude product, and washed and dried to obtain Zn3Al2(OH)8 two-dimensional bimetallic nanosheets inserted with an ultraviolet absorber; Step S5, adding the caffeic acid modified lignin ester derivative, the Zn3Al2(OH)8 two-dimensional bimetallic nanosheets inserted with the ultraviolet absorber and the thickener to the modified cyanoacrylate, stirring to obtain a multi-band absorption optical sol, coating it evenly on a glass plate, waiting for curing, and obtaining a multi-band absorption optical glue.

2. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The reaction temperature in step S1 is 100-130°C and the reaction time is 2-3h; the reaction temperature of the wood fiber with the esterifying agent and the catalyst in step S2 is 90-120°C and the reaction time is 2-5h, the reaction temperature of the lignin ester derivative with caffeic acid and the photoinitiator is 90-120°C and the reaction time is 4-6h; the reaction temperature of the zinc salt and the aluminum salt in step S3 is 25-30°C and the reaction time is 2-3h, the reaction temperature of the 2-methylimidazole and the mixture is 2 5~30℃, the reaction time is 3~4h, the washing solvent is methanol and deionized water, the freeze-drying temperature is -20~-40℃, and the freeze-drying time is 45~48h; in the step S4, the reaction temperature of solution A and solution B is 25~30℃, the reaction time is 20~24h, the drying temperature is 50~60℃, the drying time is 10~12h, and the washing reagent is deionized water; in the step S5, the stirring temperature is 25~30℃, and the stirring time is 3~4h.

3. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The average molecular weight of the polypropylene carbonate is 89000-98000 g / mol; the purity of the cyclopentanone is ≥99%; the mass ratio of the cyanoacrylate monomer, polypropylene carbonate and cyclopentanone is 1:(0.025-0.05):(4-5).

4. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The good solvent is any one or more of dimethyl sulfoxide, cyclohexane, toluene, ionic liquid and low eutectic solvent; the wood fiber is any one or more of poplar wood fiber, pine wood fiber, fir wood fiber, locust wood fiber and wood fiber powder; the esterification agent is any one or more of 2-bromoisobutyl bromide and 2-bromopropionyl bromide; the catalyst is any one or more of potassium carbonate, sodium bicarbonate, sodium hydroxide, triethylamine and 4-dimethylaminopyridine; the photoinitiator is any one or more of benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin butyl ether; the caffeic acid purity is ≥98.0%; the mass ratio of the wood fiber, good solvent, esterification agent, catalyst, caffeic acid and photoinitiator is 1:(4-5):(1-3):(0.005-0.05):(0.01-0.02):(0.005-0.01).

5. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The zinc salt is any one or more of zinc sulfate, zinc chloride, and zinc nitrate; the aluminum salt is any one or more of aluminum sulfate, aluminum chloride, and aluminum nitrate; the solvent is a mixed solution of methanol and water in a volume ratio of 1:1; the mass ratio of the zinc salt, the aluminum salt, and the solvent is 1:(1.5-2):(10-15); the alcohol solvent is any one or more of methanol, ethanol, and isopropanol; the mass ratio of 2-methylimidazole and the alcohol solvent is 1:(10-15); the volume ratio of the alcohol solution of 2-methylimidazole and the mixture is 1:

1.

6. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The ion solution is any one or more of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide; the mass ratio of salicylic acid-2-ethylhexyl ester, 2,4,6-tris(2'-hydroxy-4'-n-butoxyphenyl), anhydrous ethanol, and ion solution is 1:(1-1.5):(4-5):(1.5-2); the mass ratio of Zn3Al2(OH)8 two-dimensional bimetallic nanosheets and deionized water is 1:(4-5); the mass ratio of solution A to solution B is 1:(5-6).

7. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The mass ratio of the polypropylene carbonate modified cyanoacrylate, the caffeic acid modified lignin ester derivative, the Zn3Al2(OH)8 two-dimensional bimetallic nanosheets inserted with ultraviolet absorbers and the thickener is 1:(0.2-0.5):(0.1-0.5):(0.5-0.7); the thickener is any one or more of polyacrylic acid, carboxymethyl cellulose ether and polyacrylamide.

8. The method for preparing a multi-band absorption optical adhesive for full bonding according to claim 1, characterized in that: The thickness of the multi-band absorption optical glue is 25-250 μm.

9. A multi-band absorption optical adhesive for full bonding, characterized in that: The preparation method is described in any one of claims 1 to 8.

Images