High-temperature aging resistant UV mirror release agent and preparation method thereof

Abstract

The invention discloses a high-temperature aging resistant UV mirror release agent and a preparation method thereof, and belongs to the technical field of release agents. The preparation method comprises the following steps: firstly, mixing 75-85 parts by weight of DA type polyurethane acrylate resin, 10-20 parts by weight of a reactive diluent and 3-5 parts by weight of a photoinitiator, then adding 0.3-0.8 part by weight of a leveling agent and 0.3-0.8 part by weight of fumed silica, mixing, and then defoaming to obtain the high-temperature aging resistant UV mirror release agent. The UV mirror surface release agent provided by the invention has good high-temperature aging resistance, can release internal stress of a polymer network through reversible fracture and re-formation of D-A bonds in a high-temperature environment, inhibits cross-linking density change caused by irreversible relaxation of chain segments, drives molecular chains to move and realizes microstructure healing, and has good application prospects. The completeness of the coating and the stability of the release force are ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of release agents, and particularly relates to a UV mirror release agent resistant to high-temperature aging and a preparation method thereof. BACKGROUND

[0002] An ultraviolet (UV) curable mirror release agent is a key chemical material in the field of modern precision coating, and is widely used in high-performance pressure-sensitive adhesive tapes, optical films, flexible printed electronics and composite mold processes. Its core function is to form an extremely thin and smooth cured coating on a film (such as PET) as a carrier, which can provide just the right adhesion for the subsequent applied pressure-sensitive adhesive, firmly fixing the adhesive layer during storage and transportation, and achieving clean, smooth and low peel force demolding at the terminal application without damaging the adhesive or leaving residual images. To achieve these properties, the industry generally uses a UV curing system mainly composed of polyurethane acrylate, epoxy acrylate, etc. Through the instantaneous formation of a highly cross-linked three-dimensional network structure of multifunctional monomers and oligomers under the initiation of ultraviolet light. This network structure endows the coating with high hardness, wear resistance and excellent mechanical strength, which is the basis for obtaining mirror appearance and physical properties.

[0003] The core defect of the existing UV mirror release agent is that the cured release layer is a solid on a macroscopic scale, but the polymer chain segments always exist in micro-Brownian motion driven by thermodynamics. The relaxation and rearrangement process of the polymer chain segments will be accelerated during long-term storage, especially after experiencing high summer temperatures, transportation processes or surrounding process heat. Under the constraint of static and permanent cross-linking points, this movement of the chain segments will cause internal stress in the network and may cause uneven changes in local cross-linking density on a microscopic level. Some chain segments may slowly relax or embed into the adhesive surface, increasing the physical or weak chemical interaction between the two, and the release force of the release agent on a specific adhesive gradually increases over time or with the accumulation of heat exposure. This can easily cause abnormal peel angles, material curling or misalignment during precision processing such as die cutting and lamination, significantly increasing the rate of defective products. In addition, it also limits the stability and shelf life of the product, restricting its application in high-precision and high-reliability scenarios. Therefore, it is necessary to propose a new UV mirror release agent resistant to high-temperature aging. SUMMARY

[0004] Based on the deficiencies of the prior art, the purpose of the present application is to provide a UV mirror release agent resistant to high-temperature aging and a preparation method thereof.

[0005] The first aspect of the present application is to provide a high-temperature aging resistant UV mirror release agent, comprising the following components in mass fraction: DA type polyurethane acrylate resin 75-85 parts, active diluent 10-20 parts, photoinitiator 3-5 parts, leveling agent 0.3-0.8 parts, fumed silica 0.3-0.8 parts; Wherein, the DA type polyurethane acrylate resin is prepared by the following steps: (1) Under the protection of inert gas, bismaleimide and solvent are mixed, and furfuryl methacrylate is added dropwise for reaction, and after the reaction is completed, the reaction liquid is poured into a precipitation solution for precipitation, filtration, washing and drying to obtain a DA adduct; (2) Under the protection of inert gas, polycaprolactone diol and isophorone diisocyanate are mixed and reacted; (3) DA adduct and polymerization inhibitor are added to the reaction system of step (2) for the first reaction, and then end-capping agent and catalyst are added for the second reaction, and after the reaction is completed, impurities are removed to obtain the DA type polyurethane acrylate resin.

[0006] It should be noted that the Diels-Alder (D-A) dynamic reversible covalent bond is creatively introduced into the traditional polyurethane acrylate. First, bismaleimide (BMI, containing two maleimide groups) and bismaleimide (furfuryl methacrylate, containing two furan groups) are subjected to Diels-Alder cycloaddition reaction to generate a molecule containing D-A adduct structure and active functional groups (such as hydroxyl) at the end; at the same time, polyether / polyester polyol (long chain flexible segment) is reacted with excess diisocyanate (hard segment) to generate a prepolymer with isocyanate group (-NCO) at the end, the active group (such as hydroxyl) at the end of the synthesized D-A adduct chain extender is reacted with the -NCO group on the prepolymer, thereby introducing the D-A dynamic covalent bond into the polymer main chain; finally, the hydroxyl-containing acrylate monomer (such as hydroxyethyl acrylate HEA) is reacted with the remaining -NCO group on the chain to introduce an UV-curable acrylate double bond at the end of the chain.

[0007] In some embodiments, the mass ratio of bismaleimide and furfuryl methacrylate is 4:6-7; the solvent is selected from at least one of anhydrous tetrahydrofuran, anhydrous acetone, and N,N-dimethylformamide; and the mass amount of the solvent is 9-11 times the mass of the bismaleimide.

[0008] In some embodiments, the mass ratio of polycaprolactone diol and isophorone diisocyanate is 5:1-1.5; and the mass ratio of polycaprolactone diol and DA adduct is 5:0.8-1.2.

[0009] In some embodiments, the precipitating solution is selected from at least one of n-hexane and cyclohexane; the polymerization inhibitor is selected from at least one of hydroquinone, p-methoxyphenol, and 2,6-di-tert-butyl-p-cresol; the end-capping agent is selected from at least one of hydroxyethyl acrylate and hydroxyethyl methacrylate; and the catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, and triethylenediamine.

[0010] In some embodiments, the mass ratio of DA adduct, polymerization inhibitor, and capping agent is 10:5-6:0.05; the amount of catalyst is 100-200 ppm.

[0011] In some embodiments, in step (1), the mixing temperature is 55-65°C, and the reaction is carried out at 60-70°C for 10-14 hours.

[0012] In some embodiments, in step (2), the reaction is carried out at 75-85°C for 1.5-2.5 hours; in step (3), the first reaction is carried out at 55-65°C for 2-4 hours; and the second reaction is carried out at 70-80°C for 1-3 hours.

[0013] In some embodiments, the reactive diluent is selected from at least one of trimethylolpropane triacrylate, tripropylene glycol diacrylate, and 1,6-hexanediol diacrylate; the photoinitiator is selected from at least one of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone and benzophenone; and the leveling agent is selected from at least one of polyether-modified polydimethylsiloxane and polyester-modified polydimethylsiloxane.

[0014] A second aspect of this invention is to provide a method for preparing a UV-resistant mirror release agent that is resistant to high-temperature aging, comprising the following steps: S1: Mix DA-type polyurethane acrylate resin, reactive diluent, and photoinitiator; S2: Add leveling agent and fumed silica to the S1 mixture system, and after mixing and degassing treatment, a UV mirror release agent resistant to high temperature aging is obtained.

[0015] In some embodiments, in S1, mixing is performed by stirring at 400-600 rpm for 25-35 min; in S2, degassing is performed under vacuum conditions for 15-20 min.

[0016] Compared with the prior art, the present invention has the following technical effects: 1. This invention uses DA-type polyurethane acrylate resin to prepare a UV mirror release agent resistant to high-temperature aging. Under high-temperature storage, the DA bonds in the resin backbone achieve a dynamic equilibrium of reversible "bond breaking-reconnection", effectively releasing the internal stress of the polymer network and suppressing the change in crosslink density caused by irreversible relaxation of chain segments, thereby ensuring that the release force remains highly stable after long-term thermal aging. When the coating is damaged by scratches or other factors, the DA bonds at the damaged site can be reversibly broken and reformed through heat treatment, which can drive the movement of molecular chains and achieve the healing of the microstructure, thereby restoring the integrity and release function of the coating.

[0017] 2. The UV mirror release agent with high-temperature aging resistance provided by this invention has excellent high-temperature aging resistance and low initial release force. The release force value can remain stable under long-term storage and thermal history, making it suitable for high-end optical films, flexible electronics, high-performance tapes, and other fields that have stringent requirements for low release force and cannot tolerate performance fluctuations. Furthermore, this invention, through precise formulation and process, introduces DA bonds while ensuring high crosslinking density and surface smoothness of the coating, without affecting the mirror effect and wear resistance. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments.

[0019] Example 1 A UV-resistant mirror release agent with high temperature aging resistance comprises the following components in parts by weight: 80 parts of DA type polyurethane acrylate resin, 15 parts of reactive diluent, 4 parts of photoinitiator, 0.5 parts of leveling agent, and 0.5 parts of fumed silica. The DA-type polyurethane acrylate resin is prepared by the following steps: (1) Under inert gas protection, bismaleimide and anhydrous tetrahydrofuran were mixed at 60°C, and furan methacrylate was added dropwise and reacted at 65°C for 12 h. After the reaction was completed, the reaction solution was poured into n-hexane for precipitation, filtered, washed and dried to obtain DA adduct; wherein, the mass ratio of bismaleimide to furan methacrylate was 4:6.5, and the mass of anhydrous tetrahydrofuran was 10 times that of bismaleimide; (2) Under the protection of an inert gas, polycaprolactone diol and isophorone diisocyanate in a mass ratio of 5:1.2 were mixed and reacted at 80°C for 2 hours. (3) Add DA adduct and hydroquinone to the reaction system of step (2), react at 60°C for 3 hours, then add hydroxyethyl acrylate and dibutyltin dilaurate, react at 75°C for 2 hours, remove impurities after the reaction to obtain DA type polyurethane acrylate resin; wherein, the mass ratio of polycaprolactone diol to DA adduct is 5:1, the mass ratio of DA adduct, hydroquinone and hydroxyethyl acrylate is 10:5.5:0.05, and the amount of dibutyltin dilaurate is 150 ppm.

[0020] The above-mentioned UV-resistant release agent for high-temperature aging is prepared by the following steps: S1: Mix DA type polyurethane acrylate resin, trimethylolpropane triacrylate and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone at 400-600 rpm for 25-35 min. S2: Add polyether-modified polydimethylsiloxane and fumed silica to the S1 mixture system, and after mixing, degas under vacuum for 18 minutes to obtain a UV mirror release agent resistant to high temperature aging.

[0021] Example 2 A UV-resistant mirror release agent with high temperature aging resistance comprises the following components in parts by weight: 85 parts of DA type polyurethane acrylate resin, 20 parts of reactive diluent, 5 parts of photoinitiator, 0.8 parts of leveling agent, and 0.8 parts of fumed silica. The DA-type polyurethane acrylate resin is prepared by the following steps: (1) Under inert gas protection, bismaleimide and anhydrous acetone were mixed at 65°C, and furan methacrylate was added dropwise and reacted at 70°C for 10 h. After the reaction was completed, the reaction solution was poured into cyclohexane for precipitation, filtered, washed and dried to obtain DA adduct; wherein, the mass ratio of bismaleimide to furan methacrylate was 4:7, and the mass of anhydrous acetone was 11 times the mass of bismaleimide; (2) Under the protection of an inert gas, polycaprolactone diol and isophorone diisocyanate in a mass ratio of 5:1.5 were mixed and reacted at 85°C for 1.5 h. (3) Add DA adduct and p-methoxyphenol to the reaction system of step (2), react at 65°C for 2 hours, then add hydroxyethyl methacrylate and stannous octoate, react at 80°C for 3 hours, remove impurities after the reaction to obtain DA type polyurethane acrylate resin; wherein, the mass ratio of polycaprolactone diol and DA adduct is 5:1.2, the mass ratio of DA adduct, p-methoxyphenol and hydroxyethyl methacrylate is 10:6:0.05, and the amount of stannous octoate is 200 ppm.

[0022] The above-mentioned UV-resistant release agent for high-temperature aging is prepared by the following steps: S1: Mix DA type polyurethane acrylate resin, tripropylene glycol diacrylate and benzophenone at 600 rpm for 25 min; S2: Add polyester-modified polydimethylsiloxane and fumed silica to the S1 mixture system, and then degas under vacuum for 20 minutes to obtain a UV mirror release agent resistant to high temperature aging.

[0023] Example 3 A UV-resistant mirror release agent with high temperature aging resistance comprises the following components in parts by weight: 75 parts of DA type polyurethane acrylate resin, 10 parts of reactive diluent, 3 parts of photoinitiator, 0.3 parts of leveling agent, and 0.3 parts of fumed silica. The DA-type polyurethane acrylate resin is prepared by the following steps: (1) Under inert gas protection, bismaleimide and N,N-dimethylformamide were mixed at 55°C, and furan methacrylate was added dropwise and reacted at 60°C for 14 h. After the reaction was completed, the reaction solution was poured into n-hexane for precipitation, filtered, washed and dried to obtain DA adduct; wherein, the mass ratio of bismaleimide to furan methacrylate was 4:6, and the mass of N,N-dimethylformamide was 9 times the mass of bismaleimide; (2) Under the protection of an inert gas, polycaprolactone diol and isophorone diisocyanate in a mass ratio of 5:1 were mixed and reacted at 75°C for 2.5 h. (3) Add DA adduct and 2,6-di-tert-butyl-p-cresol to the reaction system of step (2), react at 55°C for 4 hours, then add hydroxyethyl acrylate and triethylenediamine, react at 70°C for 3 hours, remove impurities after the reaction to obtain DA type polyurethane acrylate resin; wherein, the mass ratio of polycaprolactone diol and DA adduct is 5:0.8, the mass ratio of DA adduct, 2,6-di-tert-butyl-p-cresol and hydroxyethyl acrylate is 10:5:0.05, and the amount of triethylenediamine is 100 ppm.

[0024] The above-mentioned UV-resistant release agent for high-temperature aging is prepared by the following steps: S1: Mix DA type polyurethane acrylate resin, 1,6-hexanediol diacrylate and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone at 400 rpm for 35 min. S2: Add polyether-modified polydimethylsiloxane and fumed silica to the S1 mixture system, and after mixing, degas under vacuum for 15 minutes to obtain a UV mirror release agent resistant to high temperature aging.

[0025] Example 4 It is basically the same as Example 1, except that: the UV mirror release agent with high temperature aging resistance includes the following components in parts by weight: 75-85 parts of DA type polyurethane acrylate resin, 10-20 parts of reactive diluent, 3-5 parts of photoinitiator, 0.3-0.8 parts of leveling agent, and 0.3-0.8 parts of fumed silica.

[0026] Example 5 It is basically the same as Example 1, except that: the UV mirror release agent with high temperature aging resistance includes the following components in parts by weight: 75-85 parts of DA type polyurethane acrylate resin, 10-20 parts of reactive diluent, 3-5 parts of photoinitiator, 0.3-0.8 parts of leveling agent, and 0.3-0.8 parts of fumed silica.

[0027] Comparative Example 1 This is basically the same as Example 1, except that the DA type polyurethane acrylate resin is replaced with the same amount of hexafunctional aliphatic polyurethane acrylate.

[0028] Comparative Example 2 It is basically the same as Example 1, except that the DA type polyurethane acrylate resin is replaced with a physically mixed type polyurethane acrylate resin. Physically mixed polyurethane acrylate resin is prepared by the following steps: (1) Under the protection of an inert gas, the same amount of polycaprolactone diol and isophorone diisocyanate as in Example 1 were mixed and reacted at 80°C for 2 hours. (2) Add hydroquinone, bismaleimide and furan methacrylate in the same amount as in Example 1 to the reaction system of step (1), react at 60°C for 3 hours, then add hydroxyethyl acrylate and dibutyltin dilaurate in the same amount as in Example 1, react at 75°C for 2 hours, and remove impurities after the reaction to obtain the physically mixed polyurethane acrylate resin.

[0029] The UV mirror release agents prepared in Examples 1-5 and Comparative Examples 1-2 were coated onto 25 μm PET films, with the coating dry weight controlled at 1~2 g / m. 2 Cured under a UV mercury lamp or LED lamp, with an energy of 200~400mJ / cm². 2 After curing, the release film was bonded to a standard acrylic pressure-sensitive tape (such as TESA 7475) under fixed pressure, and the performance of the release film was tested. The test results are shown in Table 1.

[0030] Release force test: Refer to standard GB / T 2792, and test the release force on a universal tensile testing machine at a peel angle of 180° and a speed of 300 mm / min. Test at least 5 points for each sample and take the average value. Heat resistance aging test: The sample was placed in an 80℃ forced-air drying oven for accelerated aging. The initial release force and the release force after 7 days of aging were tested according to the release force test standard. The release force drift rate was calculated as: Release force drift rate = (Aging force - Initial force) / Initial force × 100%; Self-healing performance evaluation: Scratches were created on the surface of the cured release film by applying a fixed load and a fixed stroke using standard steel wool (grade 0000), and then heat-treated at 80°C for 30 minutes. The changes in scratch morphology were observed using an optical microscope. Mirror finish: Refer to standard ASTM D523.

[0031] Table 1 As can be seen from Table 1, the UV mirror release agent provided in Examples 1-5 of the present invention has excellent high-temperature aging resistance, can suppress irreversible structural relaxation during thermal aging, effectively release the internal stress of the network, keep the entire network in a balanced state, and suppress the increase of release force.

[0032] As can be seen from the comparative examples, Comparative Example 1 uses hexafunctional polyurethane acrylate to form a highly cross-linked but permanent covalent network. Under high-temperature aging conditions, the thermal motion of polymer chain segments intensifies. Under the constraint of permanent cross-linking points that cannot be broken and reconnected, the chain segments slip and rearrange due to relaxed internal stress, resulting in some areas of the network becoming dense and others becoming loose. The release force continues to increase with the accumulation of thermal history. Comparative Example 2 uses a simple physical mixture of bismaleimide and furan methacrylate, which does not form DA adducts. During the UV curing process, both mainly participate in the reaction as ordinary multifunctional monomers and are randomly cured in a static network, unable to achieve self-healing and stable release force.

[0033] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A UV-resistant mirror release agent resistant to high-temperature aging, characterized in that, The product comprises the following components in parts by weight: 75-85 parts of DA type polyurethane acrylate resin, 10-20 parts of reactive diluent, 3-5 parts of photoinitiator, 0.3-0.8 parts of leveling agent, and 0.3-0.8 parts of fumed silica; The DA-type polyurethane acrylate resin is prepared by the following steps: (1) Under the protection of an inert gas, bismaleimide and solvent are mixed, and furan methacrylate is added dropwise to react. After the reaction is completed, the reaction solution is poured into a precipitation solution for precipitation. The solution is filtered, washed and dried to obtain the DA adduct. (2) Under the protection of an inert gas, polycaprolactone diol and isophorone diisocyanate are mixed and reacted; (3) Add the DA adduct and polymerization inhibitor to the reaction system of step (2) for the first reaction, then add the end-capping agent and catalyst for the second reaction, and remove the impurities after the reaction to obtain the DA type polyurethane acrylate resin.

2. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 1, characterized in that, The mass ratio of the bismaleimide to the furan methacrylate is 4:6-7; the solvent is selected from at least one of anhydrous tetrahydrofuran, anhydrous acetone, and N,N-dimethylformamide; the mass of the solvent used is 9-11 times the mass of the bismaleimide.

3. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 1, characterized in that, The mass ratio of polycaprolactone diol to isophorone diisocyanate is 5:1-1.5; the mass ratio of polycaprolactone diol to DA adduct is 5:0.8-1.

2.

4. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 1, characterized in that, The precipitate solution is selected from at least one of n-hexane and cyclohexane; the polymerization inhibitor is selected from at least one of hydroquinone, p-methoxyphenol, and 2,6-di-tert-butyl-p-cresol; the end-capping agent is selected from at least one of hydroxyethyl acrylate and hydroxyethyl methacrylate; and the catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, and triethylenediamine.

5. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 4, characterized in that, The mass ratio of the DA adduct, the polymerization inhibitor, and the capping agent is 10:5-6:0.05; the amount of catalyst is 100-200 ppm.

6. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 1, characterized in that, In step (1), the mixing temperature is 55-65℃, and the reaction is carried out at 60-70℃ for 10-14 hours.

7. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 1, characterized in that, In step (2), the reaction is carried out at 75-85℃ for 1.5-2.5h; in step (3), the first reaction is carried out at 55-65℃ for 2-4h; the second reaction is carried out at 70-80℃ for 1-3h.

8. The UV-resistant mirror release agent with high-temperature aging resistance according to claim 1, characterized in that, The reactive diluent is selected from at least one of trimethylolpropane triacrylate, tripropylene glycol diacrylate, and 1,6-hexanediol diacrylate; the photoinitiator is selected from at least one of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone and benzophenone; and the leveling agent is selected from at least one of polyether-modified polydimethylsiloxane and polyester-modified polydimethylsiloxane.

9. A method for preparing a UV-resistant mirror release agent with high-temperature aging resistance according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Mix the DA-type polyurethane acrylate resin, the reactive diluent, and the photoinitiator; S2: Add the leveling agent and the fumed silica to the S1 mixing system, and after mixing and degassing treatment, the high-temperature aging resistant UV mirror release agent is obtained.

10. The method for preparing the high-temperature aging resistant UV mirror release agent according to claim 9, characterized in that, In step S1, mixing is performed by stirring at 400-600 rpm for 25-35 minutes; in step S2, degassing is performed under vacuum conditions for 15-20 minutes.

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