A peelable PET-based film for dry film photoresist and a method for preparing the same

Abstract

The application relates to the technical field of optical films, in particular to an easy-peeling PET base film for dry film photoresist and a preparation method thereof, which is prepared by feeding PET master batch and multifunctional composite microspheres into a double-screw extruder according to a mass ratio of 85-95:5-15, melting, blending, extruding, casting, bidirectional stretching, traction and winding. The multifunctional composite microspheres prepared by the application have a unique three-layer structure of rigid SiO2 core / polyester compatible layer / fluorine-containing polymer brush, the SiO2 core significantly improves the rigidity, size stability and heat resistance of the base film; the polyester compatible layer ensures excellent compatibility and dispersibility of the microspheres and the PET matrix, and avoids the mechanical property decline and embrittlement of the film caused by adding inorganic fillers; and the polymer brush on the surface directly provides excellent peeling performance; and the prepared base film is particularly suitable for high-performance dry film photoresist and has significant market application value.

Description

Technical Field

[0001] This invention relates to the field of optical thin film technology, specifically to an easily peelable PET base film for dry film photoresist and its preparation method. Background Technology

[0002] Photoresist is a material that can transfer images through radiation or direct irradiation. Early photoresists were significantly affected by ambient humidity, limiting their application. In 1968, DuPont proposed a new type of photoresist, composed of a polyester film, a photosensitive adhesive layer, and a polyethylene protective film, commonly known as dry film. Dry film's application was unaffected by ambient humidity and was quickly accepted upon its introduction.

[0003] In dry film processing, the polyester film is typically a PET film layer, generally 10-20 μm thick, serving as a carrier and providing protection against oxygen and mechanical scratches. During exposure, light needs to pass through the polyester film layer to reach the internal photosensitive adhesive layer, requiring the polyester film to meet optical standards, i.e., high transparency and low haze. After exposure and development, the base film needs to be peeled off, necessitating easy peelability. Existing PET base films for dry films suffer from: 1. dimensional instability at high temperatures; 2. unstable peelability from the photosensitive adhesive layer, leading to adhesive residue. To improve dimensional stability and peelability, researchers have attempted to add inorganic fillers and other surface modifiers, which can improve performance to some extent. However, the addition of inorganic fillers increases film haze and decreases transparency; surface modifiers are prone to migration, affecting processing stability and durability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to design an organic hybrid microsphere containing inorganic nanoparticles and melt-blend it with PET, effectively solving the phase separation problem, achieving excellent easy-to-peel properties, while maintaining good mechanical properties and thermal stability.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing an easily peelable PET base film for dry film photoresist includes the following steps:

[0007] S1. Silica nanoparticles were prepared by adding a silane coupling agent to silica sol. The nanoparticles were then added to hydroxyl-terminated polyester oligomers and stirred at 70-100°C for 5-8 hours under nitrogen protection. After cooling, a carboxyl-terminated RAFT chain transfer agent was added, and an esterification reaction was carried out under a catalyst and an inert atmosphere to obtain a hybrid polyester prepolymer.

[0008] S2. Dilute the hybrid polyester prepolymer with ethanol to 10-20 wt%, and spray dry it using an airflow spray dryer to form hybrid microspheres;

[0009] S3. Disperse the hybrid microspheres in DMF, then add AIBN and polymerizable fluorine / silicon monomers, and heat to 60℃ under nitrogen protection for 2-6 hours. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0010] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 85~95:5~15, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0011] Further, the preparation process of the silica nanoparticles is as follows: Tetraethyl orthosilicate is dissolved in anhydrous ethanol, then a mixed solution of anhydrous ethanol and ammonia is added, and the mixture is stirred at room temperature for 4-6 hours. The reaction is stopped, and the mixture is allowed to stand and age overnight to form a silica sol. The sol is diluted with ethanol to a solid content of 3-8 wt%, then KH560 or IPTS is added, and the mixture is ultrasonically reacted for 2 hours. The mixture is then mechanically stirred and refluxed at 60°C for 8 hours, centrifuged, repeatedly washed with ethanol, and dried to obtain the final product.

[0012] Further, the hydroxyl-terminated polyester oligomer is a hydroxyl-terminated polyethylene terephthalate oligomer, a hydroxyl-terminated polybutylene succinate oligomer, or a hydroxyl-terminated hexanediol adipate oligomer, with a molecular weight of 800~1500 g / mol.

[0013] Further, the carboxyl-terminated RAFT chain transfer agent is 4-cyano-4-(phenylthiocarbonylthio)pentanoic acid; the catalyst is a mixture of N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine; and the esterification reaction temperature is 25-30 °C. o C, the reaction time is 12-24 h.

[0014] Further, in step S1, the mass ratio of silica nanoparticles to hydroxyl-terminated polyester oligomers is 1:10~50; the mass ratio of carboxyl-terminated RAFT chain transfer agent to hydroxyl-terminated polyester oligomers is 0.1~0.6:1.

[0015] Furthermore, the polymerizable fluorine / silicon monomer is selected from one or more of trifluoroethyl methacrylate, hexafluorobutyl acrylate, dodecafluoroheptyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyltriethoxysilane.

[0016] Further, in step S2, the spray drying conditions are as follows: the inlet temperature is controlled at 80~110 ℃, the outlet temperature is 50~70 ℃, the atomization pressure is 0.2~0.4MPa, and the collected sample is placed in a vacuum drying oven for further drying to obtain the final product.

[0017] Furthermore, in step S3, the mass ratio of the hybrid microspheres to AIBN and the polymerizable fluorine / silicon monomer is 1:0.01~0.05:0.5~3.

[0018] The present invention further provides an easily peelable PET base film for dry film photoresist prepared according to the preparation method described above.

[0019] Existing technologies utilize inorganic nanoparticles to achieve a smooth and hardened coating, but dispersing these nanoparticles is relatively difficult, and uneven dispersion inevitably leads to decreased film transmittance and increased haze. To address this challenge, this invention designs a core-shell-brush inorganic-organic hybrid microsphere. Rigid SiO2 nanoparticles are used as the core, combined with polyester oligomers, and then esterification is used to form a macromolecular RAFT reagent, which is copolymerized with fluorinated and silicon-containing unsaturated monomers to form a shell-brush layer structure. The polyester oligomers, especially polyethylene terephthalate, have a similar structure to the matrix and can act as compatibilizers, assisting in the dispersion of inorganic nanoparticles, preventing stress concentration that could lead to film embrittlement, and maintaining the film's high optical properties. The fluorinated and silicon-containing polymer brushes can form a uniform weak interface layer on the film surface. By melt blending, composite microspheres are uniformly dispersed in a PET matrix. During biaxial stretching and subsequent processes, the low surface energy fluoropolymer brushes on the surface of the microspheres can migrate to the film surface and remain stable, thereby forming a uniform and firm weak interface layer on the base film surface. This achieves the easy peeling function of the base film body and effectively avoids the residue of photoresist on the base film.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The "multifunctional composite microspheres" prepared in this invention possess a unique three-layer structure: a rigid SiO2 core, a polyester compatibility layer, and a fluoropolymer brush. The SiO2 core significantly improves the rigidity, dimensional stability, and heat resistance of the base film; the polyester compatibility layer ensures excellent compatibility and dispersibility between the microspheres and the PET matrix, avoiding the degradation of film mechanical properties and embrittlement caused by the addition of inorganic fillers; and the polymer brush on the surface directly provides excellent peeling performance. The prepared base film is particularly suitable for high-performance dry film photoresists and has significant market application value. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Most of the raw materials used in this application are bulk products that can be purchased on the market, such as those from Sinopharm Group, Aladdin, and Sigma-Aldrich. The RAFT chain transfer agent (4-cyano-4-(phenylthiocarbonylthio)pentanoic acid CTP) can be selected from Sigma-Aldrich. To control costs, the reagents used in this application were purchased from Shanghai Yuanye Biotechnology Co., Ltd., with a purity of 95%. It should be noted that this application only lists CTP; other carboxyl-terminated RAFT chain transfer agents that can participate in esterification reactions and other RAFT reagents capable of initiating the smooth polymerization of polymerizable fluorine / silicone monomers are also applicable to the technical solution of this application. The PET masterbatch selected is of optical grade with an intrinsic viscosity of 0.65 dl / g and must be dried before use.

[0025] Example 1: A method for preparing an easily peelable PET base film for dry film photoresist, comprising the following steps:

[0026] S1. Preparation of hybrid polyester prepolymer

[0027] S1-1. 0.5 mol tetraethyl orthosilicate was dissolved in 500 mL of anhydrous ethanol, and then 500 mL of a mixture of anhydrous ethanol and ammonia (ammonia concentration 0.2 mol / L) was added. The mixture was stirred at room temperature for 5 h, the reaction was stopped, and the mixture was allowed to stand and age overnight to form silica sol. The silica sol was diluted with ethanol to a solid content of 5 wt%. 100 mL of the sol was taken, and then 100 mL of 1 vol% IPTS ethanol solution was added. The mixture was sonicated for 2 h, mechanically stirred and refluxed at 60 ℃ for 8 h, centrifuged, repeatedly washed with ethanol, and dried to obtain nano-sized SiO2 particles.

[0028] S1-2. Add 100 mmol of dimethyl terephthalate and 150 mmol of ethylene glycol to the reactor, add 0.05 g of zinc acetate, heat to 240°C under nitrogen protection, react for 2 h, then evacuate to a low vacuum of 5000 Pa, maintain the temperature at 240°C for polycondensation reaction for 30 min, stop heating, purge with nitrogen to restore normal pressure, discharge onto a metal plate to cool, crush the solid, wash repeatedly with boiling deionized water to remove impurities, vacuum dry and crush for later use;

[0029] S1-3. Take 20g of the pulverized prepolymer, dilute it with 1 L of anhydrous THF, then add 1g of the prepared nano-sized SiO2 particles and stir until homogeneous. Under nitrogen protection, heat to 70℃ and stir for 6 hours. Then cool to 40℃, add 3g of carboxyl-terminated RAFT chain transfer agent (4-cyano-4-(phenylthiocarbonylthio)pentanoic acid) and 0.3g of 4-dimethylaminopyridine (DMAP), and stir until homogeneous. Dissolve 1.2g of N,N'-dicyclohexylcarbodiimide (DCC) in 10mL of THF, and then slowly add it dropwise to the mixed solution. Under nitrogen protection, heat to 40℃. o C, with a reaction time of 12 h, yields a hybrid polyester prepolymer.

[0030] S2. Dilute the hybrid polyester prepolymer to 10 wt% with ethanol and spray dry it using an airflow spray dryer to form hybrid microspheres. The spray drying conditions are: inlet temperature controlled at 100 ℃, outlet temperature at 70 ℃, and atomization pressure at 0.3 MPa. Place the collected sample in a vacuum drying oven for further drying to obtain the desired product.

[0031] S3. Take 10g of hybrid microspheres and disperse them in 500 mL of DMF. Then add 0.2g of AIBN, 5g of trifluoroethyl methacrylate, and 5g of γ-methacryloyloxypropyltrimethoxysilane. Under nitrogen protection, heat to 60℃ and react for 5 h. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0032] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 90:10, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0033] Example 2: A method for preparing an easily peelable PET base film for dry film photoresist, comprising the following steps:

[0034] S1. Hybrid polyester prepolymer prepared using Example 1

[0035] S2. Dilute the hybrid polyester prepolymer to 10 wt% with ethanol and spray dry it using an airflow spray dryer to form hybrid microspheres. The spray drying conditions are: inlet temperature controlled at 100 ℃, outlet temperature at 70 ℃, and atomization pressure at 0.3 MPa. Place the collected sample in a vacuum drying oven for further drying to obtain the desired product.

[0036] S3. Take 10g of hybrid microspheres and disperse them in 500 mL of DMF. Then add 0.3g of AIBN, 10g of hexafluorobutyl acrylate, and 10g of γ-methacryloyloxypropyltrimethoxysilane. Under nitrogen protection, heat to 60℃ and react for 5 h. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0037] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 90:10, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0038] Example 3: A method for preparing an easily peelable PET base film for dry film photoresist, comprising the following steps:

[0039] S1. Hybrid polyester prepolymer prepared using Example 1

[0040] S2. Dilute the hybrid polyester prepolymer to 10 wt% with ethanol and spray dry it using an airflow spray dryer to form hybrid microspheres. The spray drying conditions are: inlet temperature controlled at 100 ℃, outlet temperature at 70 ℃, and atomization pressure at 0.3 MPa. Place the collected sample in a vacuum drying oven for further drying to obtain the desired product.

[0041] S3. Take 10 g of hybrid microspheres and disperse them in 500 mL of DMF. Then add 0.5 g of AIBN, 17 g of dodecafluoroheptyl methacrylate, and 13 g of γ-methacryloyloxypropyltriethoxysilane. Under nitrogen protection, heat to 60 °C and react for 5 h. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0042] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 90:10, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0043] Example 4: A method for preparing an easily peelable PET base film for dry film photoresist, comprising the following steps:

[0044] S1. Hybrid polyester prepolymer prepared using Example 1

[0045] S2. Dilute the hybrid polyester prepolymer to 10 wt% with ethanol and spray dry it using an airflow spray dryer to form hybrid microspheres. The spray drying conditions are: inlet temperature controlled at 100 ℃, outlet temperature at 70 ℃, and atomization pressure at 0.3 MPa. Place the collected sample in a vacuum drying oven for further drying to obtain the desired product.

[0046] S3. Take 10 g of hybrid microspheres and disperse them in 500 mL of DMF. Then add 0.5 g of AIBN, 17 g of dodecafluoroheptyl methacrylate, and 13 g of γ-methacryloyloxypropyltriethoxysilane. Under nitrogen protection, heat to 60 °C and react for 5 h. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0047] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 95:5, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0048] Example 5: A method for preparing an easily peelable PET base film for dry film photoresist, comprising the following steps:

[0049] S1. Hybrid polyester prepolymer prepared using Example 1

[0050] S2. Dilute the hybrid polyester prepolymer to 10 wt% with ethanol and spray dry it using an airflow spray dryer to form hybrid microspheres. The spray drying conditions are: inlet temperature controlled at 100 ℃, outlet temperature at 70 ℃, and atomization pressure at 0.3 MPa. Place the collected sample in a vacuum drying oven for further drying to obtain the desired product.

[0051] S3. Take 10 g of hybrid microspheres and disperse them in 500 mL of DMF. Then add 0.5 g of AIBN, 17 g of dodecafluoroheptyl methacrylate, and 13 g of γ-methacryloyloxypropyltriethoxysilane. Under nitrogen protection, heat to 60 °C and react for 5 h. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0052] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 85:15, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0053] Comparative Example 1:

[0054] Using the hybrid polyester prepolymer prepared in Example 1, PET masterbatch and hybrid polyester prepolymer were fed into a twin-screw extruder at a mass ratio of 90:10, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0055] Comparative Example 2:

[0056] S1. Preparation of hybrid polyester prepolymer

[0057] S1-1. Add 100 mmol of dimethyl terephthalate and 150 mmol of ethylene glycol to the reactor, add 0.05 g of zinc acetate, heat to 240°C under nitrogen protection, react for 2 h, then evacuate to a low vacuum of 5000 Pa, maintain the temperature at 240°C for polycondensation reaction for 30 min, stop heating, purge with nitrogen to restore normal pressure, discharge the material onto a metal plate to cool, crush the solid, wash repeatedly with boiling deionized water to remove impurities, vacuum dry and crush for later use;

[0058] S1-2. Take 20g of the crushed prepolymer, dilute it with 1 L of anhydrous THF, and then add 1g of nano-SiO2 (unmodified) and stir to mix it evenly to obtain the hybrid polyester prepolymer.

[0059] S2. Dilute the hybrid polyester prepolymer to 10 wt% with ethanol and spray dry it using an airflow spray dryer to form hybrid microspheres. The spray drying conditions are: inlet temperature controlled at 100 ℃, outlet temperature at 70 ℃, and atomization pressure at 0.3 MPa. Place the collected sample in a vacuum drying oven for further drying to obtain the desired product.

[0060] S3. Take 1g of hybrid microspheres and disperse them in 500 mL of DMF. Then add 0.02g of AIBN, 0.5g of trifluoroethyl methacrylate, and 0.5g of γ-methacryloyloxypropyltrimethoxysilane. Under nitrogen protection, heat to 60℃ and react for 5 h. After the reaction is complete, precipitate in n-hexane, filter, and dry the solid to obtain multifunctional composite microspheres.

[0061] S4. PET masterbatch and multifunctional composite microspheres are fed into a twin-screw extruder at a mass ratio of 90:10, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0062] Comparative Example 3:

[0063] Nanoscale SiO2 particles and polyester oligomers were prepared according to Example 1, and then mixed with commercially available fluorosilicone compounds such as perfluorodecyltrimethoxysilane at a ratio of 1:20:10 and extruded to form composite granules.

[0064] PET masterbatch and composite granules are fed into a twin-screw extruder at a mass ratio of 90:10, and then melt-blended, extruded, cast, biaxially stretched, and wound up to obtain the final product.

[0065] Performance Testing > The base film prepared above was subjected to performance testing according to the following standards:

[0066] Thickness uniformity: The film thickness was measured using a thickness gauge according to ASTM D374. The film thickness parameter was set to 15 μm during preparation. The thickness was measured at ten points in different directions, and the relative standard deviation of the thickness was calculated from the obtained thickness values.

[0067] Transmittance %: According to ASTM D1003, using a haze meter.

[0068] Tensile strength (MPa): Refer to ASTM D 882 standard and take the TD value.

[0069] Heat shrinkage rate %: Tested according to ASTM D1204 standard, and the TD value is taken.

[0070] Peel strength: The base film is laminated with photosensitive adhesive and PE to form a dry film, and then peeled off at 180°. Observe whether there is photoresist residue on the surface of the base film.

[0071] The test results are recorded in Table 1.

[0072] Table 1

[0073]

[0074] As shown in Table 1, the technical solution provided in this application involves adding a certain amount of multifunctional composite microspheres to the PET masterbatch, which effectively improves the mechanical properties and peelability of the film. The film exhibits good dimensional stability and high thickness uniformity. The higher the content of multifunctional composite microspheres in the film, the easier it is to peel, and the better its tensile strength and heat resistance. However, the light transmittance will decrease. To save costs and obtain a film with excellent overall performance, a mass ratio of PET masterbatch to multifunctional composite microspheres of 90:10 is selected. At this ratio, Comparative Example 1 investigated the effect of a fluorosilicone polymer brush on the peel force. As shown in the table above, without fluorosilicone polymer grafting, the tensile strength and heat resistance are slightly improved, but peeling from the photosensitive adhesive is difficult, resulting in residue larger than 2 mm. Comparative Example 2 involved physically blending unmodified nano-silica particles with polyester oligomers, followed by direct in-situ free radical polymerization to form fluorosilicone polymer chains. This approach resulted in silica particles precipitating from the matrix during the melt extrusion of the multifunctional composite microspheres with PET, leaving the fluorosilicone polymer chains free on the outside of the microspheres, thus leading to a decline in various properties. Comparative Example 3 involved physically mixing SiO2 particles, polyester oligomers, and fluorosilicone polymers. While the mixture showed some compatibility with PET, inorganic particle agglomeration and small molecule migration still occurred during melt extrusion, preventing a positive improvement in the film's properties.

[0075] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for preparing a readily peelable PET-based film for dry film photoresist, characterized by, The preparation method comprises the following steps: S1, adding a silane coupling agent into a silica sol to obtain silica nanoparticles, adding the silica nanoparticles into a hydroxyl-terminated polyester oligomer, stirring and reacting at 70-100 ℃ under nitrogen protection for 5-8 h, cooling, then adding a carboxyl-terminated RAFT chain transfer agent, and performing esterification under a catalyst and an inert atmosphere to obtain a hybrid polyester prepolymer; S2, diluting the hybrid polyester prepolymer with ethanol to 10-20 wt%, and performing spray drying with an air flow type spray dryer to form hybrid microspheres; S3, dispersing the hybrid microspheres in DMF, then adding AIBN and a polymerizable fluorine / silicon monomer, and reacting at 60 ℃ under nitrogen protection for 2-6 h, then precipitating in n-hexane, and performing suction filtration and drying to obtain multifunctional composite microspheres; S4, putting PET master batches and the multifunctional composite microspheres into a double screw extruder according to a mass ratio of 85-95:5-15, melt blending, extruding, casting, bidirectional stretching, and traction winding to obtain the product. The hydroxyl-terminated polyester oligomer is a hydroxyl-terminated polyethylene terephthalate oligomer, a hydroxyl-terminated polybutylene succinate oligomer, or a hydroxyl-terminated polyhexanediol adipate oligomer, and the molecular weight is 800-1500 g / mol. The carboxyl-terminated RAFT chain transfer agent is 4-cyano-4-(phenylthiocarbonylthio)pentanoic acid; the catalyst is a mixture of N,N'-dicyclohexyl carbodiimide and 4-dimethylaminopyridine; the esterification reaction temperature is 25-30 o C, and the reaction time is 12-24 h; The polymerizable fluorine / silicon monomer is selected from one or more of trifluoroethyl methacrylate, hexafluorobutyl acrylate, dodecafluoroheptyl methacrylate, γ-methacryloyloxypropyl trimethoxysilane, and γ-methacryloyloxypropyl triethoxysilane.

2. The method for preparing the easy-peeling PET-based film for dry film photoresist according to claim 1, characterized in that, The silica nanoparticles are prepared by the following process: mixing tetraethyl orthosilicate into anhydrous ethanol, then adding a mixed solution of anhydrous ethanol and ammonia water, stirring at room temperature for 4-6 h, stopping the reaction, standing and aging overnight to form a silica sol, diluting with ethanol to a solid content of 3-8 wt%, then adding a silane coupling agent KH560 or IPTS, ultrasonic reaction for 2 h, mechanical stirring reflux at 60 ℃ for 8 h, centrifugal separation, repeated cleaning with ethanol, and drying to obtain the product.

3. The method of claim 1, wherein the method is characterized by: In step S1, the mass ratio of the silica nanoparticles to the hydroxyl-terminated polyester oligomer is 1:10-50, and the mass ratio of the carboxyl-terminated RAFT chain transfer agent to the hydroxyl-terminated polyester oligomer is 0.1-0.6:

1.

4. The method of claim 1, wherein the method is characterized by: In step S2, the spray drying conditions are as follows: the inlet temperature is controlled at 80-110 ℃, the outlet temperature is 50-70 ℃, and the atomization pressure is 0.2-0.4 MPa, and the collected sample is placed in a vacuum drying box for continuous drying.

5. The method of claim 1, wherein the method is characterized by: In step S3, the mass ratio of the hybrid microspheres to AIBN and the polymerizable fluorine / silicon monomer is 1:0.01-0.05:0.5-3.

6. The easily peelable PET base film for dry film photoresist prepared by the preparation method in any one of claims 1-5.

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