Dry film with anti-scratching polyester film

Abstract

The present application relates to the technical field of optical film, in particular to a kind of anti-scratching polyester film for dry film, there is a layer of anti-scratching coating on the surface of PET film, the anti-scratching coating includes: hyperbranched film-forming resin, nanoparticle, antistatic agent, photoinitiator, auxiliary agent, active monomer diluent, cosolvent.Compared with prior art, the present application has the following beneficial effects: by adding appropriate amount of nanoparticle, the hardness of film surface is enhanced, by constructing hyperbranched film-forming resin, nanometer particle is trapped to avoid its aggregation in coating, which leads to the decline of film optical performance; by introducing hydroxylated PEDOT / PSS, it is uniformly dispersed in coating layer, which plays a persistent and stable conductive role, and makes the film surface form persistent and stable antistatic property.

Description

Technical Field

[0001] This invention relates to the field of optical thin film technology, specifically to a scratch-resistant polyester film for dry film applications. Background Technology

[0002] Photoresist is a material that can transfer images through radiation or direct irradiation. Early photoresists were significantly affected by environmental humidity, limiting their application. In 1968, DuPont introduced 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 environmental humidity and was quickly accepted upon its introduction.

[0003] In dry film, the polyester film is typically a PET film layer, generally 10-20 μm thick. It serves as a carrier and supports the film while also protecting it from oxygen and mechanical scratches. During exposure, light needs to pass through the polyester film layer to reach the internal photosensitive adhesive layer. This requires the polyester film to meet optical standards, meaning it must have high transparency and low haze. Simultaneously, it must maintain uniform thickness to ensure consistent and even exposure. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention coats the surface of a PET film with a composite functional coating to meet the antistatic and scratch-resistant properties required by the base film for dry film, while ensuring that the film still has considerable optical properties.

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

[0006] A scratch-resistant polyester film for dry film is formed on the surface of a PET film with a scratch-resistant coating, the scratch-resistant coating comprising the following components in parts by weight:

[0007] 40-70 parts hyperbranched film-forming resin, 5-20 parts nanoparticles, 2-8 parts antistatic agent, 3-8 parts photoinitiator, 0.1-2 parts additives, 20-40 parts reactive monomer diluent, 10-20 parts cosolvent;

[0008] S1. Add polypropylene glycol and fluorinated glycol to the reaction flask, dehydrate them under vacuum, and control the temperature at 50~60℃. Add isophorone diisocyanate dropwise, with the amount of feed calculated based on the functional groups as OH:NCO=1:1.5~2.5. Add a catalytic amount of dibutyltin dilaurate catalyst, and under nitrogen protection, heat to 90℃ and react for 3 hours. After the reaction is completed, cool to 50℃ for later use.

[0009] S2. Dissolve the hydroxyl-terminated hyperbranched polyester in a small amount of propylene glycol methyl ether acetate, heat to 50~60℃, add γ-isocyanate propyltriethoxysilane and react for 2~4h. The amount of feed is calculated based on the functional groups, with OH:NCO=1:0.2~0.5.

[0010] S3. Control the temperature at 50~60℃, add the reactants from step S1 to the reaction system of step S2, and under nitrogen protection, heat to 85~95℃ and react for 2 hours. After the reaction is complete, cool down to 50℃, add the catalyst dibutyltin dilaurate, and then slowly continue to add hydroxyethyl acrylate for end-capping reaction. After the addition is complete, continue to keep the temperature for 2~6 hours. Pass the solution through a 200-300 mesh sieve while hot, and then perform vacuum distillation to adjust the solid content of the solution to 50±2%. The product is then discharged.

[0011] Furthermore, the polypropylene glycol has a number-average molecular weight of 1000, the fluorinated glycol is a perfluorinated polyether glycol with a number-average molecular weight of 1000, and the hydroxyl-terminated hyperbranched polyester is Boltorn H30 or Boltorn H40.

[0012] Furthermore, the nanoparticles are silicon dioxide or aluminum oxide with an average particle size of 10-100 nm, and are activated before use.

[0013] Further, the antistatic agent is hydroxylated PEDOT / PSS. 1-2 parts of hydroxyethyl acrylate, 4-6 parts of DMSO, and 0.08-0.1 parts of Irgacure 2959 are added sequentially to 100 parts of PEDOT / PSS dispersion. The mixture is stirred to ensure uniform dispersion. Subsequently, under nitrogen protection, it is irradiated under ultraviolet light at a light intensity of 20 mW / cm² for 30-60 min, and then the light source is removed.

[0014] Furthermore, the photoinitiator is a compound system of 1-hydroxycyclohexylphenyl ketone (UV184) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) in a mass ratio of 1 to 2:1.

[0015] Furthermore, the additives include one or more of leveling agents, wetting agents, and defoamers.

[0016] Furthermore, the active monomer diluent is a compound system of isoborneol acrylate, neopentyl glycol diacrylate, and 1,6-hexanediol diacrylate in a mass ratio of 3~5:2~4:1~3.

[0017] Furthermore, the co-solvent is a compound solution of propylene glycol methyl ether acetate and isopropanol in a volume ratio of 6:4.

[0018] Furthermore, the scratch-resistant coating is prepared by the following method:

[0019] 1) According to the formula, weigh out the measured raw materials, put the nanoparticles, one-third of the hyperbranched film-forming resin and all the cosolvent into the sand mill for dispersion to obtain a stable slurry; then, while stirring, add the remaining hyperbranched film-forming resin, photoinitiator, additives, active monomer diluent and antistatic agent to the slurry, and stir at low speed to mix evenly.

[0020] 2) Preheat the PET film to 50°C, and then coat the PET film with a wet film thickness of 1~3μm by microgravure or slit coating.

[0021] 3) Gradually raise the temperature to 80℃, and then immediately send it into an ultraviolet curing chamber for light curing to form a dense composite functional coating.

[0022] 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, the inventors designed a hyperbranched film-forming resin, pre-mixing nanoparticles with a portion of the resin and solvent to form a slurry. This hyperbranched film-forming resin uses a hyperbranched polyester core, leveraging its abundant branched hydroxyl groups to form a hyperbranched polyurethane prepolymer. The highly branched structure creates a significant steric hindrance effect in the coating solution, effectively preventing nanoparticle aggregation. The siloxane groups linked to the hyperbranched chains can co-condense with the surface-active groups of the nanoparticles, such as hydroxyl groups, effectively anchoring the nanoparticles and preventing aggregation while ensuring more uniform dispersion at different temperatures. Furthermore, the long-chain polypropylene glycol introduced into the hyperbranched polyurethane structure provides flexibility, avoiding the brittleness caused by excessive hardness; the fluorinated segments impart lower surface energy to the coating, providing some anti-fouling properties; and the hydroxyethyl acrylate end-capping forms active sites for subsequent UV curing. Reactive monomer diluents act as diluents, reducing the amount of organic solvent used while helping to lower the viscosity of the coating solution, thus enabling smooth online coating processes. They also participate in the curing and film formation process. By selecting monofunctional isobornyl acrylate and other polyfunctional monomers in combination, the curing volume shrinkage rate can be significantly reduced, minimizing internal stress on the PET substrate and ensuring low haze and high light transmittance of the film.

[0023] By surface-hydroxylating grafting modification of PEDOT / PSS, abundant hydroxyl groups are introduced onto its surface. These hydroxyl groups can form strong hydrogen bonds with urethane groups and ether bonds in the resin. More importantly, they can interact with the -Si-OH groups of the resin or the -OH groups on the surface of nanoparticles, greatly improving the compatibility and interfacial bonding of the antistatic component in the system. This effectively prevents the migration and aggregation of PEDOT / PSS during coating use or aging, ensuring the long-term stability of the conductive network.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. By adding an appropriate amount of nanoparticles to enhance the surface hardness of the film, and by constructing a hyperbranched film-forming resin, the nanoparticles are captured to prevent them from agglomerating in the coating and causing a decrease in the optical properties of the film.

[0026] 2. By introducing hydroxylated PEDOT / PSS to achieve conductivity, a durable and stable antistatic property is formed on the film surface. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] The raw materials used in this application are mostly bulk products that can be purchased on the market. The sources and models of some products are as follows:

[0030]

[0031] Example: A scratch-resistant polyester film for dry film is provided, wherein a scratch-resistant coating is formed on the surface of a PET film, the scratch-resistant coating comprising the following components in parts by weight:

[0032] 40-70 parts hyperbranched film-forming resin, 5-20 parts nanoparticles, 2-8 parts antistatic agent, 3-8 parts photoinitiator, 0.1-2 parts additives, 20-40 parts reactive monomer diluent, 10-30 parts solvent;

[0033] The hyperbranched film-forming resin is prepared by the following method:

[0034] S1. In a 1L four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet, add 100g of PPG-1000 and 100g of PFPE-diol-1000, and dehydrate under vacuum for 1 hour. Cool to 55°C, add 100g of IPDI dropwise, and add 3 drops of DBTDL. Under nitrogen protection, heat to 90°C and react for 3 hours, then cool to 50°C to obtain prepolymer A;

[0035] S2. In another reaction flask, add 70g of Boltorn H30 and 100g of PGMEA, and heat to 55℃ to dissolve. Add 37g of γ-isocyanate propyltriethoxysilane (IPTS) dropwise, and react for 3h to obtain modified hyperbranched solution B;

[0036] S3. Control the temperature at 55℃, slowly add prepolymer A dropwise to liquid B, and under nitrogen protection, raise the temperature to 85~95℃ and react for 2 hours. After the reaction is complete, cool down to 50℃, add catalyst DBTDL, and then slowly continue to add 20g of HEA dropwise for end-capping reaction. After the addition is complete, continue to keep the temperature and react for 4 hours. Pass the solution through a 200-300 mesh sieve while hot, and then perform vacuum distillation to adjust the solid content of the solution to 50±2%. The product is then discharged.

[0037] The nanoparticles are silicon dioxide, which are activated before use: after vacuum drying, the silicon dioxide is transferred to a muffle furnace preheated to 300-350°C and calcined in air or dry air for 2-4 hours, then cooled and ground.

[0038] The antistatic agent is hydroxylated PEDOT / PSS. Specifically, under light-protected conditions, 1.5 parts of hydroxyethyl acrylate, 4 parts of DMSO, and 0.09 parts of Irgacure 2959 are added sequentially to 100 parts of 1.3wt% PEDOT / PSS dispersion. The mixture is stirred to ensure uniform dispersion. Subsequently, under nitrogen protection, the mixture is irradiated under ultraviolet light at a light intensity of 20 mW / cm² for 30-60 minutes, and then the light source is removed.

[0039] The active monomer diluent is a compound system of isoborneol acrylate, neopentyl glycol diacrylate, and 1,6-hexanediol diacrylate in a mass ratio of 5:3:2.

[0040] Example 1: A scratch-resistant polyester film for dry film application

[0041] 1) According to the formula, 40 parts hyperbranched film-forming resin, 5 parts nanoparticles, 2 parts hydroxylated PEDOT / PSS, 3 parts photoinitiator, 0.1 parts additives, 20 parts reactive monomer diluent, and 10 parts solvent;

[0042] Weigh out the measured raw materials, and put the nanoparticles, one-third of the hyperbranched film-forming resin, and all the cosolvent into a sand mill for dispersion to obtain a stable slurry. Then, while stirring, add the remaining hyperbranched film-forming resin, photoinitiator, additives, active monomer diluent, and antistatic agent to the slurry, and stir at low speed to mix evenly.

[0043] 2) After vacuum dehydration, PET chips are fed into an extruder and melt-extruded at 260°C. The melt is filtered, water-cooled and formed, and then biaxially stretched, drawn, and corona-electrode to obtain a PET film with a thickness of 15μm.

[0044] 3) Preheat the PET film to 50°C, and then coat the PET film with a uniformly mixed coating liquid to a wet film thickness of 2μm by microgravure or slit coating.

[0045] 3) Gradually raise the temperature to 80℃, and then immediately send it into an ultraviolet curing chamber for light curing to form a dense composite functional coating.

[0046] Example 2: The preparation process is the same as in Example 1.

[0047] The difference lies in the formulation: 55 parts hyperbranched film-forming resin, 13 parts nanoparticles, 5 parts hydroxylated PEDOT / PSS, 5 parts photoinitiator, 1 part additive, 30 parts active monomer diluent, and 20 parts solvent.

[0048] Example 3: The preparation process is the same as in Example 1.

[0049] The difference lies in the formulation: 70 parts hyperbranched film-forming resin, 20 parts nanoparticles, 8 parts hydroxylated PEDOT / PSS, 8 parts photoinitiator, 2 parts additives, 40 parts active monomer diluent, and 30 parts solvent.

[0050] Comparative Example 1: The preparation process is the same as in Example 2.

[0051] The difference lies in using linear polyurethane instead of hyperbranched film-forming resin.

[0052] S1. In a 1L four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet, add 100g of PPG-1000 and 100g of PFPE-diol-1000, and dehydrate under vacuum for 1 hour. Cool to 55°C, add 100g of IPDI dropwise, and add 3 drops of DBTDL. Under nitrogen protection, heat to 90°C and react for 3 hours, then cool to 50°C to obtain prepolymer A;

[0053] S2. In another reaction flask, add 85g of PCL-1000 and 100g of PGMEA, and heat to 55℃ to dissolve. Add 13.4g of IPTS dropwise, react for 3 hours, and obtain solution B;

[0054] S3. Control the temperature at 55℃, slowly add one-third of the prepolymer A to liquid B, and under nitrogen protection, heat to 85~95℃ and react for 2 hours. After the reaction is complete, cool down to 50℃, add catalyst DBTDL, and then slowly continue to add 10g of HEA for end-capping reaction. After the addition is complete, continue to keep the temperature and react for 4 hours. Pass the solution through a 200-300 mesh sieve while hot, and then perform vacuum distillation to adjust the solid content of the solution to 50±2%. The product is then discharged.

[0055] Comparative Example 2: Same as Example 2

[0056] The difference lies in the fact that all the raw materials shown in the formula are put into a high-speed machine for mixing and then coated online.

[0057] Comparative Example 3: Same as Example 2

[0058] The difference is that unmodified PEDOT / PSS is used instead of hydroxylated PEDOT / PSS.

[0059] Performance Testing >

[0060] The base film prepared above was subjected to performance testing according to the following standards:

[0061] Base film dimensional stability: Measure the thickness at ten points on the base film at different locations using a micrometer, and calculate the relative standard deviation (RSD).

[0062] Pencil hardness: ASTM D3363, 750g load.

[0063] Haze and transmittance: ASTM D1003, using a haze meter.

[0064] Surface resistivity: ASTM D257, using a high-resistivity meter.

[0065] Abrasion resistance (Taber wear): ASTM D4060, CS-10 grinding wheel, 500g load, haze increment (ΔHaze) measured after 500 revolutions.

[0066] Adhesion: Cross-cut test, 1mm spacing, 3M 610 tape peel.

[0067] The test results are recorded in Table 1.

[0068] Table 1

[0069]

[0070] In Examples 1-3, with the formulation amount gradually increasing, the coating thickness gradually increases while maintaining the same wet coating amount. This leads to a gradual increase in pencil hardness and a gradual decrease in surface resistivity. However, a thicker coating also affects optical performance, resulting in increased haze and decreased light transmittance. Overall, the pencil hardness reaches 3H or higher, and the surface resistivity is above 10. 9 The light transmittance is >90%, and the haze is <1.8. Among them, Example 2 achieves a balance in all aspects of performance and is relatively optimal. Using linear polyurethane or directly mixing all materials will lead to the aggregation of nanoparticles in the matrix, resulting in a significant decrease in performance. Unmodified PEDOT / PSS also has the problem of weakened compatibility in the matrix. In addition to a significant increase in surface resistivity, other properties are also slightly weakened.

[0071] 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 dry film anti-scratch polyester film, characterized by, The anti-scratch coating layer is formed on the surface of the PET film, and the anti-scratch coating layer comprises the following components by weight: 40~70 parts of hyperbranched film-forming resin, 5~20 parts of nanoparticles, 2~8 parts of antistatic agent, 3~8 parts of photoinitiator, 0.1~2 parts of auxiliary agent, 20~40 parts of active monomer diluent, and 10~20 parts of cosolvent; The hyperbranched film-forming resin is prepared by the following method: S1, polypropylene glycol and fluorine-containing diol are added to a reaction bottle, and then vacuum dehydration is performed; the temperature is controlled at 50~60℃; isophorone diisocyanate is added dropwise, and the amount of the isophorone diisocyanate is calculated according to the functional groups therein, and OH:NCO=1:1.5~2.5; a catalytic amount of dibutyltin dilaurate is added; the temperature is raised to 90℃ under nitrogen protection; and reaction is performed for 3h; after the reaction is completed, the temperature is lowered to 50℃ for standby; S2, the hydroxyl-terminated hyperbranched polyester is dissolved in a small amount of propylene glycol methyl ether acetate; the temperature is raised to 50~60℃; γ-isocyanate propyl triethoxy silane is added; the reaction is performed for 2~4h; and the amount of the γ-isocyanate propyl triethoxy silane is calculated according to the functional groups therein, and OH:NCO=1:0.2~0.5; S3, the temperature is controlled at 50~60℃; the reactant of step S1 is added to the reaction system of step S2; the temperature is raised to 85~95℃ under nitrogen protection; and reaction is performed for 2h; after the reaction is completed, the temperature is lowered to 50℃; the catalyst dibutyltin dilaurate is supplemented; then hydroxyethyl acrylate is slowly and continuously added dropwise for end-capping reaction; after the dropwise addition is completed, the temperature is continuously maintained for 2~6h; while hot, the solution is passed through a 200-300 mesh screen; then vacuum distillation is performed; the solid content of the solution is adjusted to 50±2%; and the product is obtained; The nanoparticles are silica or alumina with an average particle size of 10~100 nm, and the nanoparticles are subjected to activation treatment before use; The antistatic agent is hydroxylated PEDOT / PSS; under light-proof conditions, 1~2 parts of hydroxyethyl acrylate, 4~6 parts of DMSO, and 0.08~0.1 parts of Irgacure 2959 are sequentially added to 100 parts of a PEDOT / PSS dispersion liquid; stirring is performed to uniformly disperse the components; then, under nitrogen protection, the solution is irradiated under ultraviolet light at a light intensity of 20 mW / cm² for 30~60 min; and the light source is removed.

2. The dry film with an anti-scratching polyester film according to claim 1, characterized by, The number average molecular weight of the polypropylene glycol is 1000; the fluorine-containing diol is a perfluoropolyether diol with a number average molecular weight of 1000; and the hydroxyl-terminated hyperbranched polyester is Boltorn H30 or Boltorn H40.

3. The dry film with an anti-scratching polyester film according to claim 1, characterized by, The photoinitiator is a compound system of 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide in a mass ratio of 1~2:

1.

4. The dry film with an anti-scratching polyester film according to claim 1, characterized by, The auxiliary agent comprises one or more of a leveling agent, a wetting agent, and a defoaming agent.

5. The dry film with an anti-scratching polyester film according to claim 1, characterized by, The active monomer diluent is a compound system of isobornyl acrylate, neopentyl glycol diacrylate, and 1,6-hexanediol diacrylate in a mass ratio of 3~5:2~4:1~3.

6. The dry film with an anti-scratching polyester film according to claim 1, characterized by, The cosolvent is a compound solution of propylene glycol methyl ether acetate and isopropyl alcohol in a volume ratio of 6:

4.

7. The dry film with an anti-scratching polyester film according to claim 1, wherein The anti-scratch coating layer is prepared by the following method: 1) According to the formula, take the metering of each raw material, put the nanoparticles and one third of the hyperbranched film-forming resin and all the cosolvents into the sand mill for dispersion, to get stable slurry; then add the remaining hyperbranched film-forming resin, photoinitiator, additives, active monomer diluent and antistatic agent to the slurry while stirring, and mix uniformly at low speed; 2) Preheat the PET film to 50℃, then coat the mixed uniform coating liquid on the PET with a wet film thickness of 1-3 μm by micro-gravure or slot coating method; 3) Gradually heat to 80℃, then immediately send into the ultraviolet light curing box for light curing to form a dense composite functional coating.

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