Ultraviolet-resistant polyester protective film and preparation method thereof

Abstract

The invention relates to an ultraviolet-resistant polyester protective film and a preparation method thereof, and belongs to the technical field of polymer composite materials. The polyester protective film comprises the following components: 5-8 wt% of a flexibilizer, 3.5-5 wt% of a lubricant, 0.18-0.24 wt% of an antioxidant, 0.32-0.45 wt% of a light stabilizer, 0.4-0.5 wt% of an anti-hydrolysis agent, 2.6-3.3 wt% of an anti-reflection agent and the balance of PET resin, 2-chloroaniline and oxalyl chloride react to form an aryl oxamide compound, namely an intermediate, the intermediate and butyl glycolate are substituted and etherified, and the intermediate and butyl glycolate undergo a reaction to form the PET protective film. A butyl-terminated ester structure is introduced, the polarity matching degree with a PET matrix is high, nanoscale uniform dispersion is achieved in the melting and mixing process, a continuous protection network is formed in the polyester matrix, free radicals are efficiently captured, full-wave-band ultraviolet rays are absorbed, aging and yellowing of the film material under the ultraviolet rays are effectively inhibited, the appearance quality of the film material is remarkably improved, and the service life of the film material is remarkably prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials, and in particular relates to an ultraviolet-resistant polyester protective film and a preparation method thereof. Background Art

[0002] Polyester film materials (such as polyethylene terephthalate (PET)) are widely used in food packaging, electronic device protection, architectural glass film, and other fields due to their light weight, high transparency, excellent mechanical strength, and chemical stability. However, polyester materials are susceptible to photooxidation reactions when exposed to ultraviolet radiation for a long time, resulting in molecular chain breakage and the formation of chromophores. This is manifested as significant yellowing and a decrease in mechanical properties, seriously affecting their service life and appearance quality. This problem is particularly prominent in outdoor or high-UV environments, limiting the long-term application potential of polyester films.

[0003] To improve the UV resistance of polyester materials, existing technologies mostly use benzotriazole or triazine light stabilizers. Benzotriazole compounds achieve protection by absorbing the UV-B band (280-320nm), but their compatibility with the polyester matrix is poor. They are prone to migration or agglomeration during high-temperature melt processing, resulting in uneven dispersion. After long-term use, the protective effect is significantly reduced. In addition, this type of compound has limited absorption capacity for the UV-A band (320-400nm), making it difficult to inhibit deep photooxidation reactions and insufficient anti-yellowing effect. Although triazine light stabilizers have broad-spectrum UV absorption capacity, their molecular polarity is high, and their interfacial bonding with hydrophobic polyester is weak. They are easily precipitated on the surface of the material, exacerbating the yellowing phenomenon.

[0004] Oxamide light stabilizers exhibit excellent anti-yellowing properties due to their unique molecular structure (containing oxamide groups and aromatic rings). This mechanism is due to the fact that the oxamide groups bind to the polyester molecular chain through hydrogen bonding or π-π stacking, effectively quenching free radicals and blocking photooxidative chain reactions. Simultaneously, the aromatic ring structure absorbs UV energy and converts it into heat. However, existing oxamide light stabilizers have poor compatibility with polyester (especially PET), making them difficult to disperse evenly during the melt-mixing process, resulting in the formation of localized agglomeration points and reduced light stabilization efficiency. Summary of the Invention

[0005] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a UV-resistant polyester protective film and a preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The invention discloses an ultraviolet-resistant polyester protective film, which comprises the following components: 5-8 wt% of a toughening agent, 3.5-5 wt% of a lubricant, 0.18-0.24 wt% of an antioxidant, 0.32-0.45 wt% of a light stabilizer, 0.4-0.5 wt% of an anti-hydrolysis agent, 2.6-3.3 wt% of a permeability enhancer, and the balance being PET resin.

[0008] The light stabilizer is prepared by the following method:

[0009] Step A1: 2-chloroaniline, potassium carbonate, and dichloromethane were premixed, dry nitrogen was introduced, and the reaction system temperature was regulated to no higher than 10°C using an ice-water bath. Oxalyl chloride was slowly added and stirred for 2.5-3 hours. The mixture was then heated and refluxed for 1-1.2 hours. After the reaction was completed, the mixture was filtered and rotary evaporated. The substrate was washed with water and dried to obtain an intermediate.

[0010] In the reaction of step A1, the ratio of oxalyl chloride, 2-chloroaniline, potassium carbonate, and dichloromethane is 10 mmol: 22-24 mmol: 2.5-3 g: 35-45 mL. 2-Chloroaniline reacts with oxalyl chloride to form an aromatic oxamide compound. The specific reaction route is as follows:

[0011]

[0012] Step A2: The intermediate, butyl glycolate, cuprous iodide, and dimethylformamide are mixed, and dry nitrogen is introduced. The temperature is raised to 70-80°C, and sodium hydride is slowly added and stirred for 8-10 hours. The temperature is then further raised to 100-110°C and stirred for 2-3 hours. After the reaction is completed, the mixture is cooled, washed with water, extracted with ethyl acetate, and the organic phase is rotary evaporated to remove the ethyl acetate to obtain a light stabilizer.

[0013] In the reaction of step A2, the ratio of the intermediate, butyl glycolate, cuprous iodide, sodium hydride, and dimethylformamide is 10 mmol: 25-28 mmol: 55-70 mg: 0.1-0.15 g: 50-60 mL. Butyl glycolate is substituted with the intermediate. The specific reaction route is as follows:

[0014]

[0015] Preferably, the toughening agent is maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymer, which has a good toughening effect on PET film.

[0016] Preferably, the lubricant is montan wax, which has an excellent lubricating effect on the PET matrix and is beneficial to the molding of the film material.

[0017] Preferably, the anti-hydrolysis agent is a polymeric carbodiimide, which has good thermal stability and matches the processing technology of the PET substrate.

[0018] Preferably, the permeability enhancer is lipophilic modified nano-silica, which has good dispersion in the PET matrix, improves the permeability of the membrane material, and enhances the mechanical strength of the membrane material.

[0019] A method for preparing an ultraviolet-resistant polyester protective film comprises the following steps: uniformly mixing various raw materials, plasticizing and extruding a casting sheet at 245-255° C., and then sequentially biaxially stretching and heat-setting to obtain the ultraviolet-resistant polyester protective film.

[0020] Beneficial effects of the present invention:

[0021] Based on the light stabilization mechanism of oxalamide compounds, the present invention develops a novel light stabilizer suitable for polyester materials. The light stabilizer is formed by reacting 2-chloroaniline with oxalyl chloride to form an aromatic oxalamide compound, i.e., an intermediate. The intermediate is then substituted and etherified with butyl glycolate to introduce a terminal butyl ester structure to obtain the light stabilizer. Compared with the prior art, the light stabilizer of the present invention has a high polarity matching degree with a PET matrix by introducing a double-terminal butyl ester structure, achieves nanometer-level uniform dispersion during the melt-mixing process, facilitates the formation of a continuous protective network in the polyester matrix, efficiently captures free radicals and absorbs ultraviolet rays of the entire wavelength range, effectively inhibits aging and yellowing of the film material under ultraviolet rays, and has a yellowness index of less than 2 after 1000 hours of accelerated aging, thereby significantly improving the appearance quality and service life of the film material. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Example 1: Preparation of UV-resistant polyester protective film. The specific implementation process is as follows:

[0024] (1) Preparation of light stabilizer

[0025] Step A1: Premix 2-chloroaniline, potassium carbonate, and dichloromethane, introduce dry nitrogen, and use an ice-water bath to control the reaction system temperature to no higher than 10°C. Slowly add oxalyl chloride and stir to react for 3 hours. Then, raise the temperature to 40°C and reflux for 1.2 hours. The amount ratio of oxalyl chloride, 2-chloroaniline, potassium carbonate, and dichloromethane is 10 mmol:22 mmol:2.5 g:35 mL. After the reaction, filter and rotary evaporate. Wash the substrate with water and dry it to obtain the intermediate.

[0026] Step A2: The intermediate, butyl glycolate, cuprous iodide, and dimethylformamide were mixed, and dry nitrogen was introduced for protection. The temperature was raised to 70°C, and sodium hydride was slowly added and stirred for 10 hours. The temperature was then continued to be raised to 100°C and stirred for 3 hours. The amount ratio of the intermediate, butyl glycolate, cuprous iodide, sodium hydride, and dimethylformamide was 10 mmol: 25 mmol: 55 mg: 0.1 g: 50 mL. After the reaction was completed, the mixture was cooled, washed with water, extracted with ethyl acetate, and the organic phase was rotary evaporated to remove ethyl acetate to obtain a light stabilizer.

[0027] (2) Preparation of membrane materials

[0028] The materials were prepared according to the following components: toughener 6wt%, using FG1901 maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymer; lubricant 5wt%, using HPL-6901 montan wax; antioxidant 0.18wt%, using antioxidant 1010 and antioxidant 168 in equal weight ratio; light stabilizer 0.32wt%, self-made in this example; anti-hydrolysis agent 0.4wt%, using 210 polymeric carbodiimide; 3.1wt% of transmittance enhancer, using VK-SP30S lipophilic modified nano-silica; the balance is PET resin, using BL8050 resin raw material;

[0029] Each component was added to a high-speed mixer and mixed at 900 rpm for 20 minutes. The mixture was plasticized and extruded into a cast sheet using an extruder at 245°C, and then biaxially stretched, wherein the longitudinal stretching ratio was 3 and the transverse stretching ratio was 4.5. The stretched film was heat-set at 180°C for 15 minutes to obtain a UV-resistant polyester protective film.

[0030] Example 2: Preparation of UV-resistant polyester protective film. The specific implementation process is as follows:

[0031] (1) Preparation of light stabilizer

[0032] Step A1: Premix 2-chloroaniline, potassium carbonate, and dichloromethane, introduce dry nitrogen, and use an ice-water bath to control the reaction system temperature to no higher than 10°C. Slowly add oxalyl chloride and stir to react for 2.5 hours. Then, raise the temperature to 40°C and reflux for 1 hour. The amount ratio of oxalyl chloride, 2-chloroaniline, potassium carbonate, and dichloromethane is 10 mmol:24 mmol:3 g:45 mL. After the reaction, filter and rotary evaporate. Wash the substrate with water and dry it to obtain the intermediate.

[0033] Step A2: The intermediate, butyl glycolate, cuprous iodide, and dimethylformamide were mixed, and dry nitrogen was introduced for protection. The temperature was raised to 80°C, and sodium hydride was slowly added and stirred for 8 hours. The temperature was then continued to be raised to 110°C and stirred for 2 hours. The amount ratio of the intermediate, butyl glycolate, cuprous iodide, sodium hydride, and dimethylformamide was 10 mmol: 28 mmol: 70 mg: 0.15 g: 60 mL. After the reaction was completed, the mixture was cooled, washed with water, extracted with ethyl acetate, and the organic phase was rotary evaporated to remove ethyl acetate to obtain a light stabilizer.

[0034] (2) Preparation of membrane materials

[0035] The following components were prepared: toughener 5wt%, using FG1901 maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymer; lubricant 3.5wt%, using HPL-6901 montan wax; antioxidant 0.22wt%, using antioxidant 1010 and antioxidant 168 in equal weight ratio; light stabilizer 0.38wt%, self-made in this example; anti-hydrolysis agent 0.4wt%, using 210 polymeric carbodiimide; 3.3wt% transmittance enhancer, using VK-SP30S lipophilic modified nano-silica; the balance is PET resin, using BL8050 resin raw material;

[0036] Each component was added to a high-speed mixer and mixed at 900 rpm for 20 minutes. The mixture was plasticized and extruded into a sheet using an extruder at 255°C, and then biaxially stretched, wherein the longitudinal stretching ratio was 3 and the transverse stretching ratio was 4.5. The stretched film was heat-set at 180°C for 15 minutes to obtain a UV-resistant polyester protective film.

[0037] Example 3: Preparation of UV-resistant polyester protective film. The specific implementation process is as follows:

[0038] (1) Preparation of light stabilizer

[0039] Step A1: Premix 2-chloroaniline, potassium carbonate, and dichloromethane, introduce dry nitrogen, and use an ice-water bath to control the reaction system temperature to no higher than 10°C. Slowly add oxalyl chloride and stir to react for 2.5 hours. Then, raise the temperature to 40°C and reflux for 1.2 hours. The amount ratio of oxalyl chloride, 2-chloroaniline, potassium carbonate, and dichloromethane is 10 mmol:23 mmol:2.8 g:45 mL. After the reaction, filter and rotary evaporate. Wash the substrate with water and dry it to obtain the intermediate.

[0040] Step A2: The intermediate, butyl glycolate, cuprous iodide, and dimethylformamide were mixed, and dry nitrogen was introduced for protection. The temperature was raised to 75°C, and sodium hydride was slowly added and stirred for 9 hours. The temperature was then continued to be raised to 100°C and stirred for 2.5 hours. The amount ratio of the intermediate, butyl glycolate, cuprous iodide, sodium hydride, and dimethylformamide was 10 mmol: 27 mmol: 60 mg: 0.13 g: 60 mL. After the reaction was completed, the mixture was cooled, washed with water, extracted with ethyl acetate, and the organic phase was rotary evaporated to remove ethyl acetate to obtain a light stabilizer.

[0041] (2) Preparation of membrane materials

[0042] The ingredients are prepared as follows: 8wt% toughener, using FG1901 maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymer; 4.5wt% lubricant, using HPL-6901 montan wax; 0.2wt% antioxidant, using antioxidant 1010 and antioxidant 168 in equal weight ratio; 0.42wt% light stabilizer, made in this example; 0.5wt% anti-hydrolysis agent, using 210 polymeric carbodiimide; 2.6wt% of transmittance enhancer, using VK-SP30S lipophilic modified nano-silica; the balance is PET resin, using BL8050 resin raw material;

[0043] Each component was added to a high-speed mixer and mixed at 900 rpm for 20 minutes. The mixture was plasticized and extruded into a cast sheet using an extruder at 250°C, and then biaxially stretched, wherein the longitudinal stretching ratio was 3 and the transverse stretching ratio was 4.5. The stretched film was heat-set at 180°C for 15 minutes to obtain a UV-resistant polyester protective film.

[0044] Example 4: Preparation of UV-resistant polyester protective film. The specific implementation process is as follows:

[0045] (1) Preparation of light stabilizer

[0046] Step A1: Premix 2-chloroaniline, potassium carbonate, and dichloromethane, introduce dry nitrogen, and use an ice-water bath to control the reaction system temperature to no higher than 10°C. Slowly add oxalyl chloride and stir to react for 3 hours. Then, raise the temperature to 40°C and reflux for 1 hour. The amount ratio of oxalyl chloride, 2-chloroaniline, potassium carbonate, and dichloromethane is 10 mmol:24 mmol:3 g:40 mL. After the reaction, filter and rotary evaporate. Wash the substrate with water and dry it to obtain the intermediate.

[0047] Step A2: The intermediate, butyl glycolate, cuprous iodide, and dimethylformamide were mixed, and dry nitrogen was introduced for protection. The temperature was raised to 80°C, and sodium hydride was slowly added and stirred for 9 hours. The temperature was then continued to be raised to 100°C and stirred for 2.7 hours. The amount ratio of the intermediate, butyl glycolate, cuprous iodide, sodium hydride, and dimethylformamide was 10 mmol: 27 mmol: 65 mg: 0.12 g: 60 mL. After the reaction was completed, the mixture was cooled, washed with water, extracted with ethyl acetate, and the organic phase was rotary evaporated to remove ethyl acetate to obtain a light stabilizer.

[0048] (2) Preparation of membrane materials

[0049] The ingredients are prepared as follows: toughener 7wt%, using FG1901 maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymer; lubricant 4.2wt%, using HPL-6901 montan wax; antioxidant 0.24wt%, using antioxidant 1010 and antioxidant 168 in equal weight ratio; light stabilizer 0.45wt%, self-made in this example; anti-hydrolysis agent 0.5wt%, using 210 polymeric carbodiimide; 2.8wt% of transmittance enhancer, using VK-SP30S lipophilic modified nano-silica; the balance is PET resin, using BL8050 resin raw material;

[0050] Each component was added to a high-speed mixer and mixed at 900 rpm for 20 minutes. The mixture was plasticized and extruded into a sheet using an extruder at 255°C, and then biaxially stretched, wherein the longitudinal stretching ratio was 3 and the transverse stretching ratio was 4.5. The stretched film was heat-set at 180°C for 15 minutes to obtain a UV-resistant polyester protective film.

[0051] Comparative Example: Referring to Example 4, the light stabilizer was replaced with commercially available 1033 type ultraviolet absorber, the rest of the implementation process is exactly the same.

[0052] Samples were taken from the protective film prepared above and subjected to accelerated UV resistance test. The specific accelerated conditions were: UVA-340 lamp, 60℃ / 85%RH, irradiation intensity 0.76W / m 2 , according to GB / T39822-2021, the yellowness index YI of different acceleration cycles is measured and the change rate δ is calculated. The specific test data are shown in Table 1:

[0053] Table 1

[0054]

[0055] As can be seen from the test results in Table 1, the film materials of Example 4 and the comparative example have similar initial yellowness indices, and the introduction of the light stabilizer has no significant effect on the initial color of the film material. During the 100-h accelerated UV aging process, the anti-aging and yellowing effects of the example and the comparative example are similar. However, during the 500-h and 1000-h accelerated processes, the yellowness index of the comparative example deteriorated sharply, and during the detection process, it was found that the comparative example had visible color spots.

[0056] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0057] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A UV-resistant polyester protective film, characterized in that: The specific components are: toughening agent 5-8wt%, lubricant 3.5-5wt%, antioxidant 0.18-0.24wt%, light stabilizer 0.32-0.45wt%, anti-hydrolysis agent 0.4-0.5wt% and transmittance enhancer 2.6-3.3wt%, and the balance is PET resin; The light stabilizer is prepared by the following method: Step A1: Premix 2-chloroaniline, potassium carbonate, and dichloromethane, introduce dry nitrogen, and control the reaction temperature to no higher than 10°C using an ice-water bath. Slowly add oxalyl chloride and stir to react for 2.5-3 hours, then reflux for 1-1.2 hours to prepare an intermediate; Step A2: The intermediate, butyl glycolate, cuprous iodide, and dimethylformamide are mixed, and dry nitrogen is introduced into the mixture. The temperature is raised to 70-80°C, and sodium hydride is slowly added and stirred for 8-10 hours. The temperature is then further raised to 100-110°C and stirred for 2-3 hours to prepare a light stabilizer.

2. The UV-resistant polyester protective film according to claim 1, characterized in that: The usage ratio of oxalyl chloride, 2-chloroaniline, potassium carbonate and dichloromethane is 10 mmol: 22-24 mmol: 2.5-3 g: 35-45 mL.

3. The UV-resistant polyester protective film according to claim 2, characterized in that: The usage ratio of the intermediate, butyl glycolate, cuprous iodide, sodium hydride and dimethylformamide is 10 mmol: 25-28 mmol: 55-70 mg: 0.1-0.15 g: 50-60 mL.

4. The UV-resistant polyester protective film according to claim 1, characterized in that: The toughening agent is maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymer.

5. The UV-resistant polyester protective film according to claim 1, characterized in that: The lubricant is montan wax.

6. The UV-resistant polyester protective film according to claim 1, characterized in that: The anti-hydrolysis agent is a polymeric carbodiimide.

7. The UV-resistant polyester protective film according to claim 1, characterized in that: The permeability enhancer is lipophilic modified nano-silica.

8. A method for preparing the UV-resistant polyester protective film according to any one of claims 1 to 7, characterized in that: Specifically, the raw materials of each component are mixed evenly, plasticized and extruded into a casting sheet at 245-255°C, and then biaxially stretched and heat-set in sequence to obtain a UV-resistant polyester protective film.

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