Novel hyperbranched structure UV resin as well as preparation method and application thereof

Abstract

The invention discloses novel hyperbranched structure UV resin as well as a preparation method and application thereof. According to the hyperbranched structure UV resin, a sulfhydrylation tetrafunctional body with a multifunctional sulfydryl structure is adopted as a cross-linking agent, sulfydryl in the cross-linking agent and isocyanate groups in aliphatic / cycloaliphatic isocyanate are subjected to nucleophilic addition reaction, and a thiocarbamate prepolymer with excessive sulfydryl is obtained; and further performing free radical polymerization reaction on the thiocarbamate prepolymer and a polyfunctional group acrylate monomer in the presence of a photoinitiator under the condition of ultraviolet irradiation to obtain the spherical hyperbranched network structure UV resin taking thiocarbamate as the core. The spherical hyperbranched UV resin provided by the invention is constructed based on sulfydryl-isocyanate reaction, is used as a functional photocuring material with rapid curing, controllable structure and excellent mechanical property, and has wide prospect and important industrialization value in application in PET film hardening treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials and light-cured resin, and particularly relates to a novel hyperbranched structure UV resin and a preparation method and application thereof. BACKGROUND

[0002] Polyethylene terephthalate (PET) film is widely used in electronic display, optical protection, printing packaging and other fields due to its excellent transparency, mechanical strength and dimensional stability. However, due to the low surface hardness of PET itself, it is easy to be scratched and worn, which limits its application in high-end optical and touch materials. Therefore, it is usually necessary to harden the surface of the PET film to improve its surface wear resistance and service life.

[0003] The existing PET film hardening treatment technology mainly includes vacuum coating, solvent type coating and energy curing coating. Among them, the ultraviolet (UV) curing coating technology has become one of the current mainstream PET surface treatment methods due to its environmental protection, high efficiency, low energy consumption and other advantages. The resin system used in the UV coating needs to have high hardness, good adhesion, fast curing ability and excellent transparency and other performances. In the existing hardening treatment materials for the surface of polyethylene terephthalate film, the traditional UV curing resin often has the problems of insufficient hardness, slow curing speed or poor adhesion with the PET substrate, which is difficult to meet the dual requirements of surface hardness and processing efficiency in the fields of high-performance optical film, display film and the like.

[0004] Traditional UV resin is mostly based on acrylate or epoxy acrylate, and forms a three-dimensional cross-linked network through free radical polymerization. However, these systems have certain limitations, such as that the reaction speed depends on the light initiator and irradiation conditions, the hardness and toughness are difficult to balance, the low molecular weight resin easily leads to high shrinkage rate, the adhesion is insufficient and the like. Therefore, developing a novel UV curing resin system with high cross-linking, compact structure, high reaction efficiency and excellent mechanical properties has become one of the hot research directions of high-performance functional film materials. SUMMARY

[0005] In order to solve the problems existing in the prior art, the present application proposes a novel hyperbranched structure UV resin and a preparation method and application thereof. The spherical hyperbranched UV resin proposed by the present application is constructed based on the mercapto-isocyanate reaction, and as a novel functional light-cured material with fast curing, controllable structure and excellent mechanical properties, it has broad prospects and important industrial value in the application of PET film hardening treatment.

[0006] The present application is realized by the following technical solutions:

[0007] A preparation method of a novel hyperbranched structure UV resin, comprising the following steps:

[0008] (1) Preparation of thio urethane prepolymer: add mercapto tetrafunctional to the reaction vessel, stir under nitrogen, then add catalyst and inhibitor, heat to 38°C-42°C, drop in aliphatic / cycloaliphatic isocyanate in several portions, interval 5-10 min, maintain reaction vessel temperature ≤60°C, after drop completion, incubate at 60°C, when NCO content is less than 0.40 wt% and no change within 30 min, determine that the step is complete, obtain thio urethane prepolymer with excess mercapto;

[0009] (2) Reduce reaction vessel temperature to below 30°C, add multifunctional acrylate monomer and photoinitiator, maintain nitrogen flow, stir for 15-30 min to uniform, turn on UV irradiation, stir while irradiating; maintain system temperature 30±2°C, when viscosity reaches 2.0×10 5 mPa·s, stop irradiation, vacuum at 45°C-50°C for 90-120 min to remove organic solvent, to less than 0.5 wt%, filter, collect product under nitrogen protection, obtain spherical hyperbranched UV resin.

[0010] The hyperbranched structure UV resin provided by the application is based on nucleophilic addition reaction between mercapto and isocyanate and subsequent free radical polymerization reaction, to construct a three-dimensional hyperbranched structure network with high hardness and rapid reaction. The addition reaction between mercapto (-SH) and isocyanate (-NCO) is a nucleophilic addition reaction, which can efficiently generate thio urethane structure under mild conditions. Such reaction not only has the advantages of fast reaction speed and high functional group utilization rate, but also the generated intermediate has good reactivity and subsequent adjustable structure, which provides a new synthesis strategy for designing UV curing materials with high branching or hyperbranched structure. By introducing mercapto compounds (such as tetra(3-mercaptopropionic acid) pentaerythritol ester) and multifunctional isocyanate, a prepolymer with three-dimensional structure can be constructed, and further light-induced crosslinking reaction with multifunctional acrylate monomer can be carried out to form a dense hyperbranched network structure, thereby significantly improving the hardness, wear resistance and curing speed of the coating.

[0011] Preferably, the mercapto tetrafunctional in step (1) is tetra(3-mercaptopropionic acid) pentaerythritol ester (PETMP), and the aliphatic / cycloaliphatic isocyanate is selected from one or more of isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI) and hexamethylene diisocyanate trimer (HDI trimer, HXR), to improve the flexibility and yellowing resistance of the final product.

[0012] Preferably, when the aliphatic / cycloaliphatic isocyanate is selected from one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, the molar ratio of the aliphatic / cycloaliphatic isocyanate, the pentaerythritol tetra(3-mercaptopropionate), and the multifunctional acrylate monomer is 2-3:3-4:8-10.

[0013] Further preferably, the molar ratio of the aliphatic / cycloaliphatic isocyanate, the pentaerythritol tetra(3-mercaptopropionate), and the multifunctional acrylate monomer is 2:3:8 or 3:4:10.

[0014] Further preferably, to ensure that there is no residual NCO, the pentaerythritol tetra(3-mercaptopropionate) and the multifunctional acrylate monomer are in excess by 1% to 2% (calculated on their own mass).

[0015] Preferably, when the aliphatic / cycloaliphatic isocyanate is selected from hexamethylene diisocyanate trimer, the molar ratio of the aliphatic / cycloaliphatic isocyanate, the pentaerythritol tetra(3-mercaptopropionate), and the multifunctional acrylate monomer is 2:5:14.

[0016] Further preferably, to ensure that there is no residual NCO, the pentaerythritol tetra(3-mercaptopropionate) and the multifunctional acrylate monomer are in excess by 1% to 2% (calculated on their own mass).

[0017] Preferably, the organic solvent in step (1) is tetrahydrofuran, and the mass ratio of the organic solvent to the total mass of the main resin, which is the sum of the mass of the pentaerythritol tetra(3-mercaptopropionate), the aliphatic / cycloaliphatic isocyanate, and the multifunctional acrylate monomer, is 35-45:55-65.

[0018] Further preferably, the organic solvent in step (1) is tetrahydrofuran, and the mass ratio of the organic solvent to the total mass of the main resin, which is the sum of the mass of the pentaerythritol tetra(3-mercaptopropionate), the aliphatic / cycloaliphatic isocyanate, and the multifunctional acrylate monomer, is 40:60.

[0019] Preferably, the catalyst in step (1) is dibutyltin dilaurate, and the mass of the catalyst is 0.02%-0.04% of the total mass of the main resin of step (1), which is the sum of the mass of the pentaerythritol tetra(3-mercaptopropionate) and the aliphatic / cycloaliphatic isocyanate.

[0020] Further preferably, the catalyst in step (1) is dibutyltin dilaurate, the mass of the catalyst is 0.03% of the total mass of the main resin in step (1), with the total mass of pentaerythritol tetrakis(3-mercaptopropionate), aliphatic / cycloaliphatic isocyanate being the total mass of the main resin in step (1).

[0021] Preferably, the inhibitor in step (1) is a mixture of p-hydroxyanisole and 2,6-di-tert-butyl-p-cresol, the mass ratio of p-hydroxyanisole and 2,6-di-tert-butyl-p-cresol is 3:1, the mass of the inhibitor is 0.03%-0.05% of the total mass of the main resin, with the total mass of pentaerythritol tetrakis(3-mercaptopropionate), aliphatic / cycloaliphatic isocyanate and multi-functional acrylate monomer being the total mass of the main resin.

[0022] Further preferably, the mass of the inhibitor is 0.04% of the total mass of the main resin, with the total mass of pentaerythritol tetrakis(3-mercaptopropionate), aliphatic / cycloaliphatic isocyanate and multi-functional acrylate monomer being the total mass of the main resin.

[0023] The intermediate prepolymer obtained in step (1) has multiple unreacted allyl groups or residual functional groups, which can further undergo a free radical polymerization reaction with multi-functional acrylate monomers in the presence of a photoinitiator under UV light irradiation to construct a structure based on a central core, which has a high cross-linking density and a spatial network topology, effectively improving the surface hardness, wear resistance and scratch resistance of the coating film.

[0024] The structural formulas of the thiolated tetra-functional, aliphatic / cycloaliphatic isocyanate and multi-functional acrylate monomer are shown in Formula 1 below.

[0025]

[0026] Formula 1

[0027] Taking hexamethylene diisocyanate (HDI) and trimethylolpropane triacrylate (TMPTA) as examples, the chemical equation involved in the preparation method is shown in Formula 2.

[0028]

[0029] Formula 2

[0030] Preferably, the multi-functional acrylate monomer in step (2) is selected from one or more of trimethylolpropane triacrylate (TMPTA), propoxylated glyceryl triacrylate (GPTA), 1,6-hexanediol diacrylate (HDDA) and bis-trimethylolpropane triacrylate (DiTMPTA).

[0031] Preferably, the photoinitiator in step (2) is Irgacure 184, the mass of the total sum of tetra(3-mercaptopropionic acid) pentaerythritol ester, aliphatic / cycloaliphatic isocyanate and multifunctional acrylate monomer as the total mass of the main resin, the mass of the photoinitiator is 0.5% of the total mass of the main resin.

[0032] The application also protects a new hyperbranched structure UV resin prepared according to the above preparation method, a thiolated tetrafunctional group with a multifunctional thiol structure is used as a crosslinking agent, nucleophilic addition reaction occurs between the thiol group in the crosslinking agent and the isocyanate group in the aliphatic / cycloaliphatic isocyanate to obtain a thiol-excessive thiourethane prepolymer, the thiourethane prepolymer further undergoes a free radical polymerization reaction with a multifunctional acrylate monomer in the presence of a photoinitiator under ultraviolet light irradiation conditions to obtain a spherical hyperbranched network structure UV resin with thiourethane as the inner core.

[0033] The application also protects the application of the new hyperbranched structure UV resin as an optical film coating or an electronic display film coating.

[0034] Preferably, the film coating is a PET film coating. The UV curing resin composition proposed by the application is suitable for rapid curing after being coated on the surface of a PET film through UV light, and the formed coating has high hardness, excellent adhesion, excellent transparency and flexibility, and is particularly suitable for optical films, electronic display films, touch panel protective films and other scenarios with high requirements for hardness and surface performance.

[0035] The application also protects the application of the new hyperbranched structure UV resin in the hardening treatment of the surface of a PET film.

[0036] Compared with the prior art, the application has the following beneficial effects:

[0037] 1) Simple and efficient synthesis process: the nucleophilic addition reaction between the thiol and the isocyanate used in the application can occur spontaneously at room temperature or under mild heating conditions, usually without the need for a metal catalyst, and only in an alkaline environment can the reaction rate be significantly accelerated, simplifying the process steps and facilitating continuous and industrial production.

[0038] 2) Excellent material performance due to hyperbranched structure: the application constructs a spherical hyperbranched network structure with thiourethane as the inner core, which significantly improves the crosslinking density and space filling capacity of the coating. Hyperbranched polymers naturally have the following advantages: a large number of terminal functional groups, which are conducive to subsequent photocuring reactions and improve curing efficiency; a loose spatial structure but a uniform distribution of crosslinking, which is conducive to forming a high-hardness coating without cracking; low intramolecular stress, which brings good flexibility and dimensional stability; excellent solubility and processing fluidity, which help to improve film uniformity and surface smoothness.

[0039] 3) Comprehensive optimization of material properties: The hyperbranched structure UV resin proposed in the present application has high hardness, excellent scratch resistance and adhesion, as well as good transparency and flexibility as a UV-cured coating, and is particularly suitable for surface functional improvement of flexible substrates such as PET film, meeting the needs of high-end applications such as optical film, display film and electronic protection film.

[0040] 4) Rapid curing and good compatibility: The residual acrylate double bonds in the reaction system can rapidly undergo free radical polymerization under UV light, achieving curing within a few seconds. The formulation has good compatibility and can be blended with various photoinitiators and diluents, adapting to mainstream UV coating equipment and high-speed roll-to-roll processes. DETAILED DESCRIPTION

[0041] The present application will be further described in conjunction with the following examples. These examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods in the following examples are not specified, and are generally carried out according to conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, if not otherwise specified, are considered to be raw materials and reagents that can be obtained through conventional market or commercial channels.

[0042] Example 1:

[0043] A method for preparing a new hyperbranched structure UV resin, comprising the following steps:

[0044] (1) Add tetra(3-mercaptopropionic acid) pentaerythritol ester (PETMP) and tetrahydrofuran (THF) to a dry reaction kettle, start stirring (250 rpm) and pass dry nitrogen. Add dibutyltin dilaurate (DBTDL) and inhibitors (p-hydroxyanisole (MEHQ) + 2,6-di-tert-butyl-p-methylphenol (BHT)), and heat to 40°C. Add hexamethylene diisocyanate (HDI) in 10 equal portions, with an interval of 8 min between each portion, and maintain the kettle temperature ≤60 °C (if necessary, turn on the jacket cooling). After the addition is complete, incubate at 60°C. Monitor the decay of the 2270 cm -1 (-NCO) peak by FTIR, and verify by titration method in parallel; when the NCO content is less than 0.40 wt% and there is no change within 30 min, it is determined that the step is complete, and a mercapto-excessive thiourethane prepolymer is obtained, with a molar ratio of HDI : PETMP : TMPTA of 2 : 3 : 8. To ensure that there is no residual NCO, the actual PETMP and TMPTA are 1%~2% in excess.

[0045] (2) The kettle temperature was reduced to 30 °C, and trimethylolpropane triacrylate (TMPTA) and Irgacure 184 were added, maintaining a slight nitrogen flow; complete deoxygenation was avoided to inhibit thermal self-polymerization, and stirring was performed for 20 min until uniformity was achieved. The 365 nm LED was turned on, and irradiation was performed while stirring; the system temperature was maintained at 30 ± 2 °C by jacket cooling. Every 10 min, a sample was taken, and when the viscosity reached 2.0 x 10 5 mPa-s, irradiation was stopped. THF was removed by vacuum at 48 °C for 100 min, until the residual solvent was less than 0.5 wt%. Filtration was performed with a 5 pm filter, and the product was collected under nitrogen protection, resulting in a spherical hyperbranched UV resin.

[0046] The raw materials and their masses used in Example 1 are listed in Table 1 below:

[0047] Table 1. Raw materials and their masses used in Example 1

[0048]

[0049] Example 2:

[0050] The same as Example 1, except that the aliphatic / cycloaliphatic diisocyanate was specifically selected as isophorone diisocyanate (IPDI), and the multifunctional acrylate was selected as glyceryl tripropoxylate triacrylate (GPTA).

[0051] The raw materials and their masses used in Example 2 are listed in Table 2 below:

[0052] Table 2. Raw materials and their masses used in Example 2

[0053]

[0054] Example 3:

[0055] The same as Example 1, except that the aliphatic / cycloaliphatic diisocyanate was specifically selected as isophorone diisocyanate (IPDI), and the multifunctional acrylate was selected as glyceryl tripropoxylate triacrylate (GPTA).

[0056] The raw materials and their masses used in Example 3 are listed in Table 3 below:

[0057] Table 3. Raw materials and their masses used in Example 3

[0058]

[0059] Example 4:

[0060] The same as example 1, the difference is that the aliphatic / cycloaliphatic diisocyanate is specifically selected to be dicyclohexyl methane diisocyanate (HMDI), and the multifunctional acrylate is selected to be double trimethylolpropane triacrylate (DiTMPTA).

[0061] The raw materials and quality used in example 4 are listed in the following table 4:

[0062] Table 4 Raw materials and quality used in example 4

[0063]

[0064] Example 5:

[0065] The same as example 1, the difference is that the aliphatic / cycloaliphatic diisocyanate is specifically selected to be isophorone diisocyanate (IPDI), and the multifunctional acrylate is selected to be double trimethylolpropane triacrylate (DiTMPTA).

[0066] The raw materials and quality used in example 5 are listed in the following table 5:

[0067] Table 5 Raw materials and quality used in example 5

[0068]

[0069] Example 6:

[0070] The same as example 1, the difference is that the aliphatic / cycloaliphatic diisocyanate is specifically selected to be hexamethylene diisocyanate trimer (HXR), and the molar ratio of HXR:PETMP:TMPTA is 2:5:14, and in order to ensure that there is no residual NCO, the actual PETMP and TMPTA are 1%-2% excess.

[0071] The raw materials and quality used in example 6 are listed in the following table 6:

[0072] Table 6 Raw materials and quality used in example 6

[0073]

[0074] Example 7:

[0075] The same as example 1, the difference is that the multifunctional acrylate is specifically selected to be 1,6-hexanediol diacrylate (HDDA), and the molar ratio of HXR:PETMP:HDDA is 2:5:14, and in order to ensure that there is no residual NCO, the actual PETMP and TMPTA are 1%-2% excess.

[0076] The raw materials and quality used in example 7 are listed in the following table 7:

[0077] Table 7 Raw materials and their amounts used in Example 7

[0078]

[0079] Example 8

[0080] The same as Example 1, except that the molar ratio of pentaerythritol tetra(3-mercaptopropionate), hexamethylene diisocyanate and trimethylolpropane triacrylate was 2:3:8, and to ensure that there was no residual NCO, the actual PETMP and TMPTA were in excess by 1% to 2%; the mass ratio of the total mass of pentaerythritol tetra(3-mercaptopropionate), hexamethylene diisocyanate and trimethylolpropane triacrylate to the total mass of the main resin was 35:65, and the mass of the inhibitor was 0.03% of the total mass of the main resin; the total mass of pentaerythritol tetra(3-mercaptopropionate) and hexamethylene diisocyanate was taken as the total mass of the main resin in step (1), and the mass of dibutyltin dilaurate was 0.02% of the total mass of the main resin in step (1).

[0081] The raw materials and their amounts used in Example 8 are listed in Table 8 below:

[0082] Table 8 Raw materials and their amounts used in Example 8

[0083]

[0084] Example 9

[0085] The same as Example 1, except that the molar ratio of pentaerythritol tetra(3-mercaptopropionate), hexamethylene diisocyanate and trimethylolpropane triacrylate was 2:3:8, and to ensure that there was no residual NCO, the actual PETMP and TMPTA were in excess by 1% to 2%; the mass ratio of the total mass of pentaerythritol tetra(3-mercaptopropionate), hexamethylene diisocyanate and trimethylolpropane triacrylate to the total mass of the main resin was 45:55, and the mass of the inhibitor was 0.05% of the total mass of the main resin; the total mass of pentaerythritol tetra(3-mercaptopropionate) and hexamethylene diisocyanate was taken as the total mass of the main resin in step (1), and the mass of dibutyltin dilaurate was 0.04% of the total mass of the main resin in step (1).

[0086] The raw materials and their amounts used in Example 9 are listed in Table 9 below:

[0087] Table 9 Raw materials and their amounts used in Example 9

[0088]

[0089] Comparative Example 1:

[0090] A conventional hexafunctional aliphatic urethane acrylate was prepared by adding 86 parts by mass of pentaerythritol acrylate (PETA) and 14 parts by mass of isophorone diisocyanate (IPDI), 0.01 parts by mass of dibutyltin dilaurate (DBTDL), 0.03 parts by mass of p-hydroxyanisole (MEHQ), and 0.01 parts by mass of 2,6-di-tert-butyl-p-cresol (BHT) into a clean reaction kettle in sequence, continuously stirring to uniform, and adding 0.01 parts by mass of antioxidant 168 (tris[2.4-di-tert-butylphenyl] phosphite) after 3 hours of incubation at 75°C. The decay of the 2270 cm -1 (-NCO) peak was monitored by FTIR, and the NCO content was verified by titration; when the NCO content was less than 0.40 wt% and no change occurred within 30 minutes, the filtrate was obtained to give the conventional hexafunctional aliphatic urethane acrylate.

[0091] The same mass of UV resins prepared in Examples 1-9 and Comparative Example 1 were added to 2 wt% (based on the UV resin) of the photoinitiator TPO and 1 wt% of the photoinitiator Irgacure 184, which were stirred and mixed uniformly, and then coated on the surface of a PET film. After curing by UV light with a wavelength of 365 nm and an energy of 300 mJ / cm 2 , test samples were prepared, and the hardness, scratch resistance, adhesion, transparency, and flexibility were compared and tested.

[0092] The following are the test methods:

[0093] Hardness: The test was performed in accordance with GB / T 6379-2006 "Pencil method for the determination of the film hardness of paints and varnishes".

[0094] Scratch resistance: Steel wool was fixed on the test head of a steel wool abrasion tester, and a 500g load was applied. The number of times of scratching was counted.

[0095] Adhesion: The test was performed in accordance with ASTM D3359 "Standard Test Methods for Measuring Adhesion by Tape Test".

[0096] Evaluation criteria:

[0097] 5B (best): The edge was completely smooth, and no squares were detached.

[0098] 4B: ≤5% detached.

[0099] 3B: 5%-15% detached.

[0100] 2B: 15%-35% detached.

[0101] 1B: 35-65% of the coating peeled off

[0102] OB (worst): >65% of the area peeled off.

[0103] Transparency: The light transmittance was tested using a hazemeter.

[0104] Flexibility: The sample was folded in half and bent 180° around itself, and pressed for 3 s. After each folding, a 10x magnifying glass was used to check if there was any visible crack. The more folds it could withstand before a crack appeared, the better the flexibility.

[0105] The test results are shown in Table 10 below.

[0106] Table 10 PET coating performance test data

[0107]

[0108] As can be seen from Table 10, the spherical hyperbranched UV resin has higher hardness and better scratch resistance, while having good adhesion, light transmittance and flexibility. The UV curing resin composition is suitable for coating on the surface of a PET film and then rapidly curing under UV light. The formed coating has high hardness, excellent adhesion, excellent transparency and flexibility, and is particularly suitable for optical films, electronic display films, touch panel protective films and other scenarios with high requirements for hardness and surface performance.

[0109] The above examples are only used to help understand the technical solutions of the present application and its core idea. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing a novel hyperbranched structure UV resin, characterized in that, Comprising the following steps: (1) Preparation of thiocarbamate prepolymer: add mercaptan tetrafunctional to the reaction vessel, stir under nitrogen, then add catalyst and inhibitor, heat to 38°C-42°C, drop in aliphatic / cycloaliphatic isocyanate in several portions, interval 5-10 min, maintain reaction vessel temperature ≤60°C, after drop completion, incubate at 60°C, when NCO content is less than 0.40 wt% and no change within 30 min, determine that the step is complete, obtain thiocarbamate prepolymer with excess mercaptan; (2) The temperature of the reaction vessel is reduced to below 30°C, and a multi-functional acrylate monomer and a photoinitiator are added. The system is stirred at a low nitrogen flow rate for 15-30 minutes until it is uniform, and then UV irradiation is started while stirring. The temperature of the system is maintained at 30±2°C, and when the viscosity reaches 2.0x10 5 mPa-s, the irradiation is stopped, and the system is vacuumed at 45-50°C for 90-120 minutes to remove the organic solvent, until the residual organic solvent is less than 0.5 wt%. The product is collected by filtration under nitrogen protection, to obtain a spherical hyperbranched UV resin.

2. The production method according to claim 1, characterized by, The mercaptan tetrafunctional in step (1) is pentaerythritol tetra(3-mercaptopropionate), and the aliphatic / cycloaliphatic isocyanate is selected from one or more of isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and hexamethylene diisocyanate trimer.

3. The production method according to claim 1 or 2, characterized by, When the aliphatic / cycloaliphatic isocyanate is selected from one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate, the molar ratio of aliphatic / cycloaliphatic isocyanate, pentaerythritol tetra(3-mercaptopropionate), and multifunctional acrylate monomer is 2-3:3-4:8-10.

4. The production method according to claim 1 or 2, characterized by, When the aliphatic / cycloaliphatic isocyanate is selected from hexamethylene diisocyanate trimer, the molar ratio of aliphatic / cycloaliphatic isocyanate, pentaerythritol tetra(3-mercaptopropionate), and multifunctional acrylate monomer is 2:5:

14.

5. The production method according to claim 1 or 2, characterized by, The organic solvent in step (1) is tetrahydrofuran, and the mass ratio of the total mass of the organic solvent to the total mass of the main resin is 35-45:55-65, with the total mass of pentaerythritol tetra(3-mercaptopropionate), aliphatic / cycloaliphatic isocyanate, and multifunctional acrylate monomer being the total mass of the main resin.

6. The production method according to claim 1 or 2, characterized by, The catalyst in step (1) is dibutyltin dilaurate, and the mass of the catalyst is 0.02%-0.04% of the total mass of the main resin of step (1), with the total mass of pentaerythritol tetra(3-mercaptopropionate) and aliphatic / cycloaliphatic isocyanate being the total mass of the main resin of step (1); the inhibitor is a mixture of p-hydroxyanisole and 2,6-di-tert-butyl-p-methylphenol, and the mass ratio of p-hydroxyanisole to 2,6-di-tert-butyl-p-methylphenol is 3:1; the mass of the inhibitor is 0.03%-0.05% of the total mass of the main resin, with the total mass of pentaerythritol tetra(3-mercaptopropionate), aliphatic / cycloaliphatic isocyanate, and multifunctional acrylate monomer being the total mass of the main resin.

7. The preparation method according to claim 1, characterized in that, The multifunctional acrylate monomer in step (2) is selected from one or more of trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, 1,6-hexanediol diacrylate, and ditrimethylolpropane triacrylate.

8. The novel hyperbranched structure UV resin prepared by the preparation method of claim 1, characterized in that, The thiolated tetrafunctional group with multi-functional thiol structure is used as a crosslinking agent, the thiol in the crosslinking agent and the isocyanate group in the aliphatic / cycloaliphatic isocyanate undergo nucleophilic addition reaction to obtain a thiol-excessive thiourethane prepolymer, the thiourethane prepolymer further undergoes free radical polymerization reaction with a multi-functional acrylate monomer in the presence of a photoinitiator under ultraviolet light irradiation to obtain a spherical hyperbranched network structure UV resin with thiourethane as the inner core.

9. Application of the novel hyperbranched structure UV resin obtained by the preparation method of claim 1 or 2 or the novel hyperbranched structure UV resin of claim 8 as an optical film coating or an electronic display film coating.

10. Application of the novel hyperbranched structure UV resin obtained by the preparation method of claim 1 or 2 or the novel hyperbranched structure UV resin of claim 8 in PET film surface hardening treatment.

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