Low viscosity LED photocurable polyester resin and method for preparing the same

Abstract

The present application relates to the technical field of light-cured resin, and particularly relates to a low-viscosity LED light-cured polyester resin and a preparation method thereof, which is composed of the following components: modified polyester acrylate, modified polyethylene glycol, isobornyl acrylate, LED photoinitiator, leveling agent BYK-371, defoaming agent BYK-055, UV stabilizer, and adhesion promoter; the present application introduces dynamic reversible bonds and ion-conducting groups by designing a hyperbranched polyester acrylate skeleton and a functional modified polyethylene glycol synergistic system, and combines with precise process control; compared with the prior art, the resin can realize recyclable recovery and self-repairing function while maintaining ultralow viscosity, and has ion-conducting characteristics; the curing efficiency is improved, the batch stability reaches the industrial standard, and the resin has wide application prospects in the fields of precise 3D printing, flexible electronic packaging, and environment-friendly light-cured coating, etc.

Description

Technical Field

[0001] This invention relates to the field of photocurable resin technology, and in particular to a low-viscosity LED photocurable polyester resin and its preparation method. Background Technology

[0002] Photocurable resin is a polymer material that can be rapidly cross-linked and cured under ultraviolet or visible light irradiation. Its core components include oligomers, reactive diluents, and photoinitiators. Among the existing photocurable systems, epoxy acrylate, polyurethane acrylate, and polyester acrylate are the three most widely used resins. As environmentally friendly materials, they do not require heating during the curing process and have zero VOC emissions, making them widely used in 3D printing, electronic packaging, coatings, and other fields.

[0003] In existing technologies, photocurable resins have high viscosity, requiring the addition of a high proportion of diluent to reduce their viscosity, which leads to a decrease in their mechanical properties. In addition, the cross-linked network in the cured resin is irreversible and lacks self-healing ability. Furthermore, the existing curing resins have low curing efficiency, which limits their application scenarios.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a low-viscosity LED photocurable polyester resin and its preparation method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a low-viscosity LED photocurable polyester resin and its preparation method, so as to solve the problems of low mechanical properties, low curing efficiency and limited application range in the prior art.

[0006] To achieve the above objectives, the present invention provides a low-viscosity LED photocurable polyester resin and its preparation method.

[0007] A low-viscosity LED-curable polyester resin is composed of the following components: modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, LED photoinitiator, leveling agent BYK-371, defoamer BYK-055, UV stabilizer, and adhesion promoter.

[0008] The mass ratio of the modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, leveling agent BYK-371, defoamer BYK-055, UV stabilizer, and adhesion promoter is 1:0.3-0.5:0.75-0.8:0.006-0.008:0.003-0.005:0.02-0.025:0.015-0.02.

[0009] Furthermore, the mass ratio of the LED photoinitiator to the total mass of the modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, leveling agent BYK-371, defoamer BYK-055, UV stabilizer, and adhesion promoter is 0.06-0.065:1.

[0010] Preferably, the preparation steps of the modified polyester acrylate are as follows:

[0011] Step A1: Under a nitrogen atmosphere, pentaerythritol and hexahydrophthalic anhydride are added to a four-necked flask, heated to 170-180℃, melted and mixed, cooled to 140-150℃, p-toluenesulfonic acid catalyst and hydroquinone polymerization inhibitor are added, and the reaction is maintained at this temperature for 3-5 hours. The temperature is then lowered to 80-90℃, hydroxyethyl acrylate is added, the temperature is raised to 100-120℃, and the reaction is carried out for 2-4 hours. Once the reaction is complete, hyperbranched polyester acrylate is obtained.

[0012] Step A2: Under a nitrogen atmosphere, add the modified bisphenol A diglycidyl ether resin to a flask, heat to 30-50℃, add dibutyltin dilaurate, stir for 8-12 minutes, add hyperbranched polyester acrylate, heat to 65-75℃, add hydroquinone as a polymerization inhibitor, react for 2-4 hours, after the reaction is complete, cool to 30-40℃, decolorize with activated carbon, filter, and distill under reduced pressure to obtain the modified polyester acrylate.

[0013] Preferably, the mass ratio of pentaerythritol, hexahydrophthalic anhydride, hydroxyethyl acrylate, catalyst p-toluenesulfonic acid, and polymerization inhibitor hydroquinone in step A1 is 1:4.7-4.8:3.3-3.5:0.045-0.05:0.009-0.01;

[0014] The mass ratio of the modified bisphenol A diglycidyl ether resin, hyperbranched polyester acrylate, dibutyltin dilaurate, and polymerization inhibitor hydroquinone in step A2 is 1:0.24-0.25:0.0012-0.0013:0.0012-0.0015;

[0015] By using pentaerythritol as the core and hexahydrophthalic anhydride ring-opening esterification to form a three-dimensional spherical hyperbranched framework, the entanglement between molecules is reduced. At the same time, the high-density distribution of terminal acrylate groups of the hyperbranched polyester acrylate on the molecular surface can reduce internal friction, thereby reducing the viscosity of the resin.

[0016] Preferably, the modified bisphenol A diglycidyl ether resin is prepared as follows:

[0017] Step B1: Add bisphenol A diglycidyl ester to tetrahydrofuran solvent, heat to 80-85℃, introduce carbon dioxide, pressurize to 0.5-0.6MPa, add tetrabutylammonium bromide catalyst, react for 10-12h to obtain bisphenol A cyclic carbonate.

[0018] Step B2: Add bisphenol A cyclic carbonate and acrylic acid to toluene solvent, stir and mix, heat to 90-95℃, add the catalyst tetrabutylammonium bromide and hydroquinone, react for 4-5 hours, after the reaction is complete, distill under reduced pressure to obtain modified bisphenol A diglycidyl ether resin.

[0019] Preferably, in step B1, the mass ratio of bisphenol A diglycidyl ester, carbon dioxide, and the catalyst tetrabutylammonium bromide is 1:0.4-0.65:0.01-0.03;

[0020] In step B2, the mass ratio of bisphenol A cyclic carbonate, acrylic acid, the catalyst tetrabutylammonium bromide, and hydroquinone is 1:0.38-0.42:0.035-0.045:0.002-0.003.

[0021] Preferably, the modified polyethylene glycol is prepared as follows:

[0022] Step C1: Under a nitrogen atmosphere, polyethylene glycol 6000 and lithium hydride are added to a reaction vessel, heated to 70-90℃, rotated at 150-250 rpm, and reacted for 1-3 hours to obtain dehydrated polyethylene glycol 6000.

[0023] Step C2: Add dehydrated polyethylene glycol 6000 to a tetrahydrofuran solution, cool to -5 to -0°C, add triethylamine, heat to 0 to 5°C, stir and react for 20 to 40 minutes to obtain a mixture;

[0024] Step C3: Under a nitrogen atmosphere, acryloyl chloride is added to a tetrahydrofuran solution, stirred and dissolved, heated to -2 to -2°C, the mixture is added, the temperature is raised to 20 to 30°C, and the reaction is carried out for 7 to 9 hours. Lithium bis(trifluoromethanesulfonyl)imide and hydroquinone are added, the temperature is raised to 50 to 60°C, and the reaction is stirred for 12 to 14 hours. The mixture is then distilled under reduced pressure to obtain modified polyethylene glycol.

[0025] Modified polyethylene glycol 6000, by introducing a long-chain ether oxygen structure, can act as a lubricant in the resin system. At the same time, the -O- of polyethylene glycol forms hydrogen bonds with the carboxyl groups of polyester, which can quickly break and recombine under shear force, achieving shear thinning behavior and thus reducing viscosity. In addition, it also endows the material with self-healing ability, enabling the curing resin to be recycled and reducing resource waste.

[0026] Preferably, the mass ratio of polyethylene glycol 6000 to lithium hydride in step C1 is 1:0.004-0.005;

[0027] The mass ratio of dehydrated polyethylene glycol 6000 to triethylamine in step C2 is 1:0.16-0.17;

[0028] In step C3, the mass ratio of acryloyl chloride, the mixture, lithium bis(trifluoromethanesulfonyl)imide, and hydroquinone is 0.07-0.08:1:0.28-0.29:0.0004-0.0006.

[0029] A method for preparing a low-viscosity LED-curable polyester resin, comprising the following steps:

[0030] Step S1: Add the modified polyester acrylate to the reaction vessel, heat to 50-70℃, add the modified polyethylene glycol, stir for 8-12 minutes, add isobornyl acrylate, stir for 15-25 minutes, then add the leveling agent and defoamer, stir for 10-20 minutes at 700-900 rpm, cool to 40-50℃, add the UV stabilizer, stir for 8-12 minutes at 300-500 rpm, add the adhesion promoter, stir for 8-12 minutes, and after stirring is complete, a homogeneous solution is obtained.

[0031] Step S2: Add the homogenized solution to a beaker, heat to 20-30℃, add LED photoinitiator, stir for 20-40 minutes at 300-500 rpm, and sieve to obtain low-viscosity LED photocurable polyester resin.

[0032] By synergizing with the LED photoinitiator system, the curing efficiency is improved. At the same time, the bis(trifluoromethanesulfonyl)imide lithium ion group introduced by the modified polyethylene glycol gives the resin ionic conductivity, extending its application to the field of flexible electronic packaging. In addition, while maintaining mechanical properties, it also has low viscosity, self-healing, conductivity and fast curing characteristics, making it suitable for cutting-edge fields such as precision 3D printing, environmentally friendly coatings, and flexible electronic device packaging, breaking through the application limitations of traditional photocurable resins.

[0033] Preferably, the mass ratio of modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, leveling agent, defoamer, UV stabilizer and adhesion promoter in step S1 is 1:0.3-0.5:0.75-0.8:0.006-0.008:0.003-0.005:0.02-0.025:0.015-0.02;

[0034] The mass ratio of the homogeneous solution to the LED photoinitiator in step S2 is 1:0.06-0.065.

[0035] The beneficial effects of this invention are:

[0036] This invention provides a low-viscosity LED photocurable polyester resin and its preparation method. By designing a hyperbranched polyester acrylate backbone and a functionally modified polyethylene glycol synergistic system, dynamic reversible bonds and ion-conducting groups are introduced. Combined with precise process control, compared with existing technologies, this resin achieves recyclability and self-healing functions while maintaining ultra-low viscosity, and is endowed with ion-conducting properties. It also improves curing efficiency and achieves batch stability to industrial-grade standards, showing broad application prospects in precision 3D printing, flexible electronic packaging, and environmentally friendly photocurable coatings. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0038] The sources and properties of some of the raw materials used in this invention are as follows:

[0039] Example 1: A method for preparing a modified bisphenol A diglycidyl ether resin is as follows:

[0040] S1: Add 100g of bisphenol A diglycidyl ester to 200mL of tetrahydrofuran solvent, heat to 80℃, introduce 40g of carbon dioxide, pressurize to 0.6MPa, add 1g of tetrabutylammonium bromide catalyst, react for 10h to obtain bisphenol A cyclic carbonate.

[0041] S2: Add 100g of bisphenol A cyclic carbonate and 38g of acrylic acid to 200mL of toluene solvent, stir and mix, heat to 90℃, add 3.5g of tetrabutylammonium bromide catalyst and 0.2g of hydroquinone, react for 5h, the reaction is completed, distill under reduced pressure to obtain modified bisphenol A diglycidyl ether resin.

[0042] Example 2: A method for preparing a modified bisphenol A diglycidyl ether resin is as follows:

[0043] S1: Add 100g of bisphenol A diglycidyl ester to 200mL of tetrahydrofuran solvent, heat to 83℃, introduce 50g of carbon dioxide, pressurize to 0.55MPa, add 2g of tetrabutylammonium bromide catalyst, react for 11h to obtain bisphenol A cyclic carbonate.

[0044] S2: Add 100g of bisphenol A cyclic carbonate and 40g of acrylic acid to 200mL of toluene solvent, stir and mix, heat to 93℃, add 4g of tetrabutylammonium bromide catalyst and 0.25g of hydroquinone, react for 4.5h, the reaction is complete, distill under reduced pressure to obtain modified bisphenol A diglycidyl ether resin.

[0045] Example 3: A method for preparing a modified bisphenol A diglycidyl ether resin is as follows:

[0046] S1: Add 100g of bisphenol A diglycidyl ester to 200mL of tetrahydrofuran solvent, heat to 85℃, introduce 65g of carbon dioxide, pressurize to 0.5MPa, add 3g of tetrabutylammonium bromide catalyst, react for 12h to obtain bisphenol A cyclic carbonate.

[0047] S2: Add 100g of bisphenol A cyclic carbonate and 42g of acrylic acid to 200mL of toluene solvent, stir and mix, heat to 95℃, add 4.5g of tetrabutylammonium bromide catalyst and 0.3g of hydroquinone, react for 4h, the reaction is completed, distill under reduced pressure to obtain modified bisphenol A diglycidyl ether resin.

[0048] Example 4: The preparation steps of a modified polyester acrylate are as follows:

[0049] S1: Under a nitrogen atmosphere, 100g of pentaerythritol and 470g of hexahydrophthalic anhydride were added to a four-necked flask, heated to 170°C, melted and mixed, cooled to 150°C, 4.5g of the catalyst p-toluenesulfonic acid and 0.9g of the polymerization inhibitor hydroquinone were added, the reaction was maintained at this temperature for 3 hours, cooled to 90°C, 330g of hydroxyethyl acrylate was added, the temperature was raised to 100°C, and the reaction was carried out for 4 hours. The reaction was completed, and hyperbranched polyester acrylate was obtained.

[0050] S2: Under a nitrogen atmosphere, 100g of modified bisphenol A diglycidyl ether resin was added to a flask, heated to 30°C, 0.12g of dibutyltin dilaurate was added, and the mixture was stirred for 12 minutes. Then, 24g of hyperbranched polyester acrylate was added, the temperature was raised to 65°C, and 0.12g of the polymerization inhibitor hydroquinone was added. The reaction was carried out for 2 hours until the reaction was complete. The temperature was then lowered to 40°C, the mixture was decolorized with activated carbon, filtered, and distilled under reduced pressure to obtain the modified polyester acrylate.

[0051] Example 5: The preparation steps of a modified polyester acrylate are as follows:

[0052] S1: Under a nitrogen atmosphere, 100g of pentaerythritol and 475g of hexahydrophthalic anhydride were added to a four-necked flask, heated to 175°C, melted and mixed, cooled to 145°C, 4.7g of the catalyst p-toluenesulfonic acid and 0.95g of the polymerization inhibitor hydroquinone were added, the reaction was maintained at this temperature for 4 hours, cooled to 85°C, hydroxyethyl acrylate was added, the temperature was raised to 110°C, and the reaction was carried out for 3 hours. The reaction was completed, and hyperbranched polyester acrylate was obtained.

[0053] S2: Under a nitrogen atmosphere, 100g of modified bisphenol A diglycidyl ether resin was added to a flask, heated to 40℃, 0.125g of dibutyltin dilaurate was added, and the mixture was stirred for 10min. Then, 24.5g of hyperbranched polyester acrylate was added, the temperature was raised to 70℃, and 0.14g of the polymerization inhibitor hydroquinone was added. The reaction was carried out for 3h until the reaction was complete. The temperature was then lowered to 35℃, the mixture was decolorized with activated carbon, filtered, and distilled under reduced pressure to obtain the modified polyester acrylate.

[0054] Example 6: The preparation steps of a modified polyester acrylate are as follows:

[0055] S1: Under a nitrogen atmosphere, 100g of pentaerythritol and 480g of hexahydrophthalic anhydride were added to a four-necked flask, heated to 180°C, melted and mixed, cooled to 140°C, 5g of the catalyst p-toluenesulfonic acid and 1g of the polymerization inhibitor hydroquinone were added, the reaction was kept at this temperature for 5h, cooled to 80°C, 350g of hydroxyethyl acrylate was added, the temperature was raised to 120°C, and the reaction was carried out for 2h. The reaction was completed, and hyperbranched polyester acrylate was obtained.

[0056] S2: Under a nitrogen atmosphere, 100g of modified bisphenol A diglycidyl ether resin was added to a flask, heated to 50°C, 0.13g of dibutyltin dilaurate was added, and the mixture was stirred for 12 minutes. Then, 25g of hyperbranched polyester acrylate was added, the temperature was raised to 65°C, and 0.15g of hydroquinone, a polymerization inhibitor, was added. The reaction was carried out for 4 hours until the reaction was complete. The temperature was then lowered to 30°C, the mixture was decolorized with activated carbon, filtered, and distilled under reduced pressure to obtain the modified polyester acrylate.

[0057] Example 7: A method for preparing modified polyethylene glycol is as follows:

[0058] S1: Under a nitrogen atmosphere, 100g of polyethylene glycol 6000 and 0.4g of lithium hydride were added to a reaction vessel, heated to 70°C, rotated at 250 rpm, and reacted for 1 hour to obtain dehydrated polyethylene glycol 6000.

[0059] S2: Add 100g of dehydrated polyethylene glycol 6000 to 200mL of tetrahydrofuran solution, cool to -5℃, add 16g of triethylamine, heat to 5℃, stir and react for 20min to obtain a mixture;

[0060] S3: Under a nitrogen atmosphere, 7g of acryloyl chloride was added to 200mL of tetrahydrofuran solution, stirred and dissolved, heated to -2℃, 100g of the mixture was added, heated to 30℃, and reacted for 7h. Then, 28g of lithium bis(trifluoromethanesulfonyl)imide and 0.04g of hydroquinone were added, heated to 50℃, stirred and reacted for 14h, and distilled under reduced pressure to obtain modified polyethylene glycol.

[0061] Example 8: A method for preparing modified polyethylene glycol is as follows:

[0062] S1: Under a nitrogen atmosphere, 100g of polyethylene glycol 6000 and 0.5g of lithium hydride were added to a reaction vessel, heated to 80℃, rotated at 200rpm, and reacted for 2h to obtain dehydrated polyethylene glycol 6000.

[0063] S2: Add 100g of dehydrated polyethylene glycol 6000 to 200mL of tetrahydrofuran solution, cool to -3℃, add 16.5g of triethylamine, heat to 3℃, stir and react for 30min to obtain a mixture;

[0064] S3: Under a nitrogen atmosphere, 7.5 g of acryloyl chloride was added to 200 mL of tetrahydrofuran solution, stirred and dissolved, heated to 0 °C, 100 g of the mixture was added, the temperature was raised to 20-30 °C, and the reaction was carried out for 8 h. Then, 28.5 g of lithium bis(trifluoromethanesulfonyl)imide and 0.05 g of hydroquinone were added, the temperature was raised to 55 °C, and the reaction was stirred for 13 h. The mixture was then distilled under reduced pressure to obtain modified polyethylene glycol.

[0065] Example 9: A method for preparing modified polyethylene glycol is as follows:

[0066] S1: Under a nitrogen atmosphere, 100g of polyethylene glycol 6000 and 0.5g of lithium hydride were added to a reaction vessel, heated to 90℃, rotated at 150rpm, and reacted for 3h to obtain dehydrated polyethylene glycol 6000.

[0067] S2: Add 100g of dehydrated polyethylene glycol 6000 to 200mL of tetrahydrofuran solution, cool to -0℃, add 17g of triethylamine, heat to 0℃, stir and react for 40min to obtain a mixture;

[0068] S3: Under a nitrogen atmosphere, 8g of acryloyl chloride was added to 200mL of tetrahydrofuran solution, stirred and dissolved, heated to 2℃, 100g of the mixture was added, heated to 20℃, and reacted for 9h. Then, 29g of lithium bis(trifluoromethanesulfonyl)imide and 0.06g of hydroquinone were added, heated to 60℃, stirred and reacted for 14h, and distilled under reduced pressure to obtain modified polyethylene glycol.

[0069] Example 10: A method for preparing a low-viscosity LED photocurable polyester resin is as follows:

[0070] S1: Add 100g of modified polyester acrylate to the reactor, heat to 50℃, add 30g of modified polyethylene glycol, stir for 12min, add 75g of isobornyl acrylate, stir for 25min, then add 0.6g of leveling agent and 0.3g of defoamer, stir for 10min at 900rpm, cool to 40℃, add 2g of UV stabilizer, stir for 8min at 500rpm, add 1.5g of adhesion promoter, stir for 12min, and after stirring is complete, a homogeneous solution is obtained.

[0071] S2: Add 100g of homogenized solution to a beaker, heat to 20℃, add 6g of LED photoinitiator, stir for 40min at 300rpm, and sieve to obtain low-viscosity LED photocurable polyester resin.

[0072] Example 11: A method for preparing a low-viscosity LED photocurable polyester resin is as follows:

[0073] S1: Add 100g of modified polyester acrylate to the reactor, heat to 60℃, add 40g of modified polyethylene glycol, stir for 10min, add 78g of isobornyl acrylate, stir for 20min, then add 0.7g of leveling agent and 0.4g of defoamer, stir for 15min at 800rpm, cool to 45℃, add 2.3g of UV stabilizer, stir for 10min at 400rpm, add 1.8g of adhesion promoter, stir for 10min, and after stirring is complete, a homogeneous solution is obtained;

[0074] S2: Add 100g of homogenized solution to a beaker, heat to 25℃, add 6.3g of LED photoinitiator, stir for 30min at 400rpm, and sieve to obtain low-viscosity LED photocurable polyester resin.

[0075] Example 12: A method for preparing a low-viscosity LED photocurable polyester resin is as follows:

[0076] S1: Add 100g of modified polyester acrylate to the reactor, heat to 70℃, add 50g of modified polyethylene glycol, stir for 8min, add 80g of isobornyl acrylate, stir for 25min, then add 0.8g of leveling agent and 0.5g of defoamer, stir for 10min at 900rpm, cool to 40℃, add 2.5g of UV stabilizer, stir for 8min at 500rpm, add 2g of adhesion promoter, stir for 8min, and after stirring is complete, a homogeneous solution is obtained;

[0077] S2: Add 100g of homogenized solution to a beaker, heat to 30℃, add 6.5g of LED photoinitiator, stir for 20min at 500rpm, and sieve to obtain low-viscosity LED photocurable polyester resin.

[0078] Comparative Example 1:

[0079] Compared with Example 10, this comparative example did not add lithium bis(trifluoromethanesulfonyl)imide during the preparation of modified polyethylene glycol. All other steps and parameters were the same, and will not be repeated here. The final result was a low-viscosity LED light-curing polyester resin.

[0080] Comparative Example 2:

[0081] This comparative example differs from Example 10 only in that "modified polyester acrylate" is replaced with "polyester acrylate". All other steps and parameters are the same, and will not be repeated here. The final result is a low-viscosity LED light-curing polyester resin.

[0082] Comparative Example 3:

[0083] Compared with Example 10, this comparative example only replaces "modified polyethylene glycol" with "polyethylene glycol 6000". All other steps and parameters are the same, and will not be repeated here. The final result is a low-viscosity LED light-curing polyester resin.

[0084] Comparative Example 4:

[0085] This comparative example differs from Example 10 only in that the "LED photoinitiator" is replaced with the "UV initiator". All other steps and parameters are the same, and will not be repeated here. The final result is a low-viscosity LED photocurable polyester resin.

[0086] Comparative Example 5:

[0087] Compared with Example 10, this comparative example only replaces "polyethylene glycol 6000" with "polyethylene glycol 400". All other steps and parameters are the same, and will not be repeated here. The final result is a low-viscosity LED light-curing polyester resin.

[0088] Performance testing:

[0089] Viscosity test:

[0090] The DV2T-RV viscometer was used in accordance with the GB / T2794-2013 testing standard.

[0091] 1. Take 20 mL each of the polyester resins from Examples 10-12 and Comparative Examples 1-5, place them in the sample cell, heat to 25 ± 0.5 °C, equilibrate for 10 min, and set a shear rate gradient of 100 s. -1 200S -1 500S-1 1000S -1 Record the average torque T 1-4

[0092] 2. Viscosity values ​​at various shear rates: η = K × T; (K is the rotor constant);

[0093] 3. Calculate the coefficient of variation:

[0094]

[0095] Table 1 Example 10 780±15 1.2 Example 11 790±12 1.5 Example 12 800±14 1.8 Comparative Example 1 790±20 1.3 Comparative Example 2 3200±150 5.0 Comparative Example 3 1500±100 4.5 Comparative Example 4 780±18 1.2 Comparative Example 5 3600±200 6.0

[0096] Self-repair efficiency test:

[0097] Scratch repair method: Take the cured resins from Examples 10-12 and Comparative Examples 1-5, and cut them into 10×10×2mm pieces. 3 The surface was polished, and scratches with a depth of 50±5μm were created using a diamond scribing needle. The surface was placed on a 60℃ temperature-controlled platform, and the scratch morphology was observed every 30 minutes using a laser confocal microscope to calculate the repair rate.

[0098] Table 2 Example 10 0.50 0.04 92±3 Example 11 0.50 0.05 90±2 Example 12 0.50 0.045 91±3 Comparative Example 1 0.50 0.075 85±5 Comparative Example 2 0.50 0.30 40±4 Comparative Example 3 0.50 0.40 20±4 Comparative Example 4 0.50 0.04 92±3 Comparative Example 5 0.50 0.35 30±3

[0099] Ion conductivity test:

[0100] Referring to the IEC 62631-3-1 standard "Dielectric properties of solid insulating materials", a 1260A impedance analyzer was used.

[0101] 1. Take 5 mL of each of the curing resins from Examples 10-12 and Comparative Examples 1-5, coat them evenly between two stainless steel electrodes with a spacing of 100 μm, cure them with an LED lamp, apply a 10 mV AC signal, and record the data.

[0102] 2. Calculate the volume resistance R b Resistivity formula: d: electrode spacing, A: contact area.

[0103] Table 3 Example 10 31.25 <![CDATA[3.20×10 -4 ]]> Example 11 32.26 <![CDATA[3.10×10 -4 ]]> Example 12 33.33 <![CDATA[3.00×10 -4 ]]> Comparative Example 1 <![CDATA[1.00×10 6 ]]> <![CDATA[1.00×10 -8 ]]> Comparative Example 2 33.3 <![CDATA[3.00×10 -4 ]]> Comparative Example 3 <![CDATA[8.33×10 5 ]]> <![CDATA[1.20×10 -8 ]]> Comparative Example 4 32.26 <![CDATA[3.10×10 -4 ]]> Comparative Example 5 50.00 <![CDATA[2.00×10 -4 ]]>

[0104] Curing efficiency test

[0105] Take 5 mL each of the cured resins from Examples 10-12 and Comparative Examples 1-5, and coat them evenly onto a KBr salt plate. Monitor the 810 cm⁻¹ FTIR using a Nicolet-iS50. -1 Intensity of the characteristic peak of the C=C bond in acrylic acid was measured, and the double bond conversion rate was calculated. And record the time t required for the conversion rate to reach 95%.

[0106] Mechanical performance testing

[0107] Referring to the GB / T 6739-2006 test standard, 20 mL of each of the cured resins from Examples 10-12 and Comparative Examples 1-5 were taken and uniformly coated onto a 100×100×3 mm glass plate. 3 LED curing, wavelength 385nm, 50mW / cm 2 The curing time is 60 seconds. A pencil is fixed to the hardness tester with the tip at a 45° angle to the sample surface. The test starts with the softest pencil (1H) and gradually increases to harder pencils. The test is stopped when scratches or film cracks are visible.

[0108] Adhesion test

[0109] 1. Referring to the ASTM D3359 test standard, take the cured resin of Examples 10-12 and Comparative Examples 1-5, cut through the coating to the substrate to form a 6×6 grid, press the tape tightly against the grid area, press it with your fingers 5 times to ensure complete contact, and quickly tear off the tape at 60°.

[0110] 2. Result rating 0 5B Optimal adhesion ≤5% (1-5 grids) 4B good 6-15% 3B qualified 16-35% 2B Unqualified ≥36% 0B Severe shedding

[0111] Interlayer bonding strength test:

[0112] Referring to the ISO 4624 testing standard, take 10 mL of the cured resin from Examples 10-12 and Comparative Examples 1-5, cure under LED light, cut into 40 mm pieces, polish the cut surfaces, coat with fast-drying epoxy adhesive, align and bond, with an overlap area A of 20 × 20 mm. 2 Curing was performed under pressure of 0.2 MPa at 25°C for 24 hours. The sample was then subjected to vertical tensile testing using a universal testing machine until interlayer peeling occurred, and the maximum peel force F was recorded. max Formula for calculating bond strength: ,

[0113] Data Analysis:

[0114] As can be seen from Table 1, the LED photocurable polyester resin prepared by this invention has lower viscosity, efficient self-healing function, high ionic conductivity, rapid curing and high mechanical strength.

[0115] Comparative Example 1, lacking lithium bis(trifluoromethanesulfonyl)imide, exhibits lower conductivity. This is because lithium bis(trifluoromethanesulfonyl)imide is the core component providing lithium ions, and it can dissociate into Li. + and TFSI- Li + Complexing with long-chain ether oxygen groups (—O—) in polyethylene glycol allows them to migrate within the polymer network, forming ion-conducting channels, TFSI - The large volume structure can reduce the ion association energy and increase the ion dissociation degree, thereby stabilizing the anion;

[0116] Comparative Example 2 showed that the viscosity increased because the modified polyester acrylate was replaced with polyester acrylate. This was because the unmodified polyester acrylate would cause the molecules to become more entangled, and the linear structure would cause it to lose its steric hindrance. In contrast, the terminal acrylate groups in the modified polyester acrylate were densely distributed on the molecular surface, which could reduce internal friction and thus reduce the viscosity of the resin.

[0117] In Comparative Example 3, the self-healing ability of the modified polyethylene glycol 6000 was reduced because the modified polyethylene glycol 6000 introduced a long-chain ether oxygen structure, which can play a lubricating role in the resin system. At the same time, the -O- of polyethylene glycol forms hydrogen bonds with the polyester carboxyl groups, which can break and recombine quickly under shear force, achieving shear thinning behavior and thus reducing viscosity.

[0118] Comparative Example 4 shows that the curing speed is reduced because the traditional UV initiator is replaced by the LED initiator. This is because the traditional TPO initiator has insufficient absorption efficiency under 385nm LED light.

[0119] Comparative Example 5 shows that the mechanical strength is reduced because polyethylene glycol 400 is used instead of polyethylene glycol 6000. This is because the short chains of polyethylene glycol 400 cannot penetrate the interlayer for anchoring, and the hydrogen bond density is too low to provide more force for fixation.

[0120] In summary, Comparative Examples 1-3 demonstrate that the absence of any functional component will lead to the collapse of individual performance characteristics. Comparative Example 4 highlights the decisive role of LED initiators in curing efficiency. Furthermore, Comparative Example 5 reveals that the long-chain structure of polyethylene glycol 6000 is the molecular basis for simultaneously achieving low viscosity, self-healing, and strong interlayer bonding.

[0121] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0122] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A low-viscosity LED photocurable polyester resin, characterized in that, It is composed of the following components: modified polyester acrylate, modified polyethylene glycol, isobornyl acrylate, LED photoinitiator, leveling agent BYK-371, defoamer BYK-055, UV stabilizer, and adhesion promoter. The mass ratio of the modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, leveling agent BYK-371, defoamer BYK-055, UV stabilizer, and adhesion promoter is 1:0.3-0.5:0.75-0.8:0.006-0.008:0.003-0.005:0.02-0.025:0.015-0.

02. Furthermore, the mass ratio of the LED photoinitiator to the total mass of the modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, leveling agent BYK-371, defoamer BYK-055, UV stabilizer, and adhesion promoter is 0.06-0.065:

1. The preparation steps of the modified polyester acrylate are as follows: Step A1: Under a nitrogen atmosphere, pentaerythritol and hexahydrophthalic anhydride are added to a four-necked flask, heated to 170-180℃, melted and mixed, cooled to 140-150℃, p-toluenesulfonic acid catalyst and hydroquinone polymerization inhibitor are added, and the reaction is maintained at this temperature for 3-5 hours. The temperature is then lowered to 80-90℃, hydroxyethyl acrylate is added, the temperature is raised to 100-120℃, and the reaction is carried out for 2-4 hours. Once the reaction is complete, hyperbranched polyester acrylate is obtained. Step A2: Under a nitrogen atmosphere, add the modified bisphenol A diglycidyl ether resin to a flask, heat to 30-50℃, add dibutyltin dilaurate, stir for 8-12 minutes, add hyperbranched polyester acrylate, heat to 65-75℃, add the polymerization inhibitor hydroquinone, react for 2-4 hours, after the reaction is complete, cool to 30-40℃, decolorize with activated carbon, filter, and distill under reduced pressure to obtain the modified polyester acrylate; The modified bisphenol A diglycidyl ether resin is prepared as follows: Step B1: Add bisphenol A diglycidyl ester to tetrahydrofuran solvent, heat to 80-85℃, introduce carbon dioxide, pressurize to 0.5-0.6MPa, add tetrabutylammonium bromide catalyst, react for 10-12h to obtain bisphenol A cyclic carbonate. Step B2: Add bisphenol A cyclic carbonate and acrylic acid to toluene solvent, stir and mix, heat to 90-95℃, add the catalyst tetrabutylammonium bromide and hydroquinone, react for 4-5 hours, after the reaction is complete, distill under reduced pressure to obtain modified bisphenol A diglycidyl ether resin. The modified polyethylene glycol is prepared as follows: Step C1: Under a nitrogen atmosphere, polyethylene glycol 6000 and lithium hydride are added to a reaction vessel, heated to 70-90℃, rotated at 150-250 rpm, and reacted for 1-3 hours to obtain dehydrated polyethylene glycol 6000. Step C2: Add dehydrated polyethylene glycol 6000 to a tetrahydrofuran solution, cool to -5 to -0°C, add triethylamine, heat to 0 to 5°C, stir and react for 20 to 40 minutes to obtain a mixture; Step C3: Under a nitrogen atmosphere, acryloyl chloride is added to a tetrahydrofuran solution, stirred and dissolved, heated to -2 to -2°C, the mixture is added, the temperature is raised to 20 to 30°C, and the reaction is carried out for 7 to 9 hours. Lithium bis(trifluoromethanesulfonyl)imide and hydroquinone are added, the temperature is raised to 50 to 60°C, and the reaction is stirred for 12 to 14 hours. The mixture is then distilled under reduced pressure to obtain modified polyethylene glycol.

2. The low-viscosity LED photocurable polyester resin according to claim 1, characterized in that, The mass ratio of pentaerythritol, hexahydrophthalic anhydride, hydroxyethyl acrylate, the catalyst p-toluenesulfonic acid, and the polymerization inhibitor hydroquinone in step A1 is 1:4.7-4.8:3.3-3.5:0.045-0.05:0.009-0.01; The mass ratio of the modified bisphenol A diglycidyl ether resin, hyperbranched polyester acrylate, dibutyltin dilaurate, and the polymerization inhibitor hydroquinone in step A2 is 1:0.24-0.25:0.0012-0.0013:0.0012-0.0015.

3. The low-viscosity LED photocurable polyester resin according to claim 1, characterized in that, In step B1, the mass ratio of bisphenol A diglycidyl ester, carbon dioxide, and the catalyst tetrabutylammonium bromide is 1:0.4-0.65:0.01-0.

03. In step B2, the mass ratio of bisphenol A cyclic carbonate, acrylic acid, the catalyst tetrabutylammonium bromide, and hydroquinone is 1:0.38-0.42:0.035-0.045:0.002-0.

003.

4. The low-viscosity LED photocurable polyester resin according to claim 1, characterized in that, The mass ratio of polyethylene glycol 6000 to lithium hydride in step C1 is 1:0.004-0.005; The mass ratio of dehydrated polyethylene glycol 6000 to triethylamine in step C2 is 1:0.16-0.17; In step C3, the mass ratio of acryloyl chloride, the mixture, lithium bis(trifluoromethanesulfonyl)imide, and hydroquinone is 0.07-0.08:1:0.28-0.29:0.0004-0.0006.

5. A method for preparing a low-viscosity LED photocurable polyester resin according to any one of claims 1-4, characterized in that, The preparation steps are as follows: Step S1: Add the modified polyester acrylate to the reaction vessel, heat to 50-70℃, add the modified polyethylene glycol, stir for 8-12 minutes, add isobornyl acrylate, stir for 15-25 minutes, then add the leveling agent and defoamer, stir for 10-20 minutes at 700-900 rpm, cool to 40-50℃, add the UV stabilizer, stir for 8-12 minutes at 300-500 rpm, add the adhesion promoter, stir for 8-12 minutes, and after stirring is complete, a homogeneous solution is obtained. Step S2: Add the homogenized solution to a beaker, heat to 20-30℃, add LED photoinitiator, stir for 20-40 minutes at 300-500 rpm, and sieve to obtain low-viscosity LED photocurable polyester resin.

6. The method for preparing a low-viscosity LED photocurable polyester resin according to claim 5, characterized in that, The mass ratio of modified polyester acrylate, modified polyethylene glycol, isoborneol acrylate, leveling agent, defoamer, UV stabilizer and adhesion promoter mentioned in step S1 is 1:0.3-0.5:0.75-0.8:0.006-0.008:0.003-0.005:0.02-0.025:0.015-0.02; The mass ratio of the homogeneous solution to the LED photoinitiator in step S2 is 1:0.06-0.065.

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