High-permeability low-fog BOPET (Biaxially Oriented Polyester) film

Abstract

The invention discloses a high-permeability low-fog BOPET (Biaxially Oriented Polyester) film, and belongs to the technical field of polyester films. Comprising a substrate layer and a functional surface layer, the base material layer accounts for 80-90% of the total mass of the BOPET film and is prepared from the following raw materials in parts by mass: 73-85 parts of polyethylene glycol terephthalate resin, 0.5-0.9 part of a nucleating agent, 1-2 parts of an anti-blocking agent and 1.2-2.8 parts of an antioxidant; the functional surface layer accounts for 10-20% of the total mass of the BOPET film and is prepared from the following raw materials in parts by mass: 67-79 parts of polyethylene glycol terephthalate resin and 3-9 parts of an antibacterial agent; wherein the nucleating agent can reduce haze; the antibacterial agent is composed of nano-zinc oxide and a chloramine antibacterial agent, the antibacterial property and the flexibility of the film can be improved, and the antibacterial time is long, so that the problem that the transparency, the antibacterial property and the flexibility of a traditional BOPET film cannot be considered at the same time is solved, and the BOPET film has important application value in the technical field of polyester films.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester films, and in particular relates to a high-transmittance and low-fog BOPET film. Background Art

[0002] Biaxially oriented polyester film (BOPET), a high-performance polymer film material, plays a key role in numerous fields. Made primarily from polyethylene terephthalate (PET), it undergoes a series of processes, including crystallization and drying, extrusion and melting, sheet casting, and biaxial stretching and orientation. BOPET film boasts numerous advantages, including high mechanical strength, excellent temperature resistance, superior electrical insulation, and chemical resistance, making it widely used in industries such as packaging, electronics, and optics. For example, in the electronics sector, ultra-thin BOPET film can serve as a substrate for flexible printed circuits (FPCs), meeting the trend toward thinner, lighter, and smaller electronic devices. Its excellent insulation properties also ensure the stable operation of electronic components. In the optical field, the high transmittance and glossiness of some BOPET films make them ideal for applications such as polarizer protective films and MLCC (multi-layer ceramic capacitor) release films, effectively supporting the high-precision manufacturing of electronic components.

[0003] However, existing BOPET films still face several pressing challenges in practical applications. With the continuous advancement of technology and the increasing demand for visually appealing products, existing BOPET films are no longer able to meet the transparency requirements in some high-end applications. For example, in the field of high-end optical displays, film transparency and low haze are extremely stringent requirements. Conventional BOPET films, due to their high haze, can reduce display clarity and color reproduction, impacting the visual experience. Furthermore, with the rise of flexible electronics, such as the development and production of flexible displays and wearable electronic devices, stringent requirements have been placed on the tensile properties of BOPET films as flexible substrate materials. Existing BOPET films are prone to molecular chain breakage, film thinning, or even cracking when subjected to a certain degree of stretch. This makes it difficult to ensure the stability and reliability of flexible electronic devices during bending and folding, limiting their application. Finally, BOPET films lack antibacterial properties, allowing bacteria to easily grow on the film surface. Frequent contact with the human body can pose certain health risks. Existing technologies often only address some of the aforementioned issues, failing to address all of them simultaneously. Often, addressing one issue only exacerbates another. In summary, there is an urgent need to invent a BOPET film that can solve the above problems at the same time to meet people's growing demand for high-quality products. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a high-transmittance and low-fog BOPET film.

[0005] The object of the present application can be achieved by the following technical solutions: A high-transmission and low-haze BOPET film, comprising a substrate layer and a functional surface layer; The substrate layer accounts for 80-90% of the total mass of the BOPET film and is composed of the following mass parts of raw materials: 73-85 parts of polyethylene terephthalate resin, 0.5-0.9 parts of nucleating agent, 1-2 parts of anti-blocking agent, and 1.2-2.8 parts of antioxidant; The functional surface layer accounts for 10-20% of the total mass of the BOPET film and is composed of the following mass parts of raw materials: 67-79 parts of polyethylene terephthalate resin, 3-9 parts of antibacterial agent.

[0006] As a further technical solution, the nucleating agent is one of sodium benzoate, aluminum p-t-butylbenzoate, and sorbitol derivatives.

[0007] As a further technical solution, the antioxidant is one of triphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, and tris(nonylphenyl) phosphite.

[0008] As a further technical solution, the anti-blocking agent is one of erucic acid amide, oleic acid amide, and stearic acid amide.

[0009] As a further technical solution, the antibacterial agent is obtained by compounding nano-zinc oxide and chloramine antibacterial agent at a mass ratio of 1:2; wherein the chloramine antibacterial agent is prepared by the following steps: Step 1, in a three-necked round-bottom flask, sequentially add hydrochloric acid (mass fraction 37%), p-hydroxybenzaldehyde, and biuret, mechanically stir at room temperature for 8-12 h, after the reaction is completed, add ice water, wash with distilled water until pH≈5, filter and dry, recrystallize to obtain product A; Step 2, in a three-necked round-bottom flask, sequentially add tetrahydrofuran, product A, and stearoyl chloride, after stirring and mixing, add triethylamine and 4-dimethylamino pyridine as catalyst, stir uniformly, heat to 40-60℃, keep the temperature for 6-8 h, after the reaction is completed, remove the solvent by rotary evaporation, recrystallize with dichloromethane to obtain product B; Step 3, in a three-necked round-bottom flask, sequentially add sodium hypochlorite solution (mass fraction 12%) and product B, mechanically stir at room temperature for 2-4 h, since the reaction is exothermic, no heating is required, after the reaction is completed, remove the solvent by rotary evaporation, purify by column chromatography, and finally dry under vacuum at 60℃-70℃ to obtain the chloramine antibacterial agent.

[0010] As a further technical solution, in step 1, the ratio of hydrochloric acid, p-hydroxybenzaldehyde and biuret is 95.1g:12.2g:10.3g.

[0011] As a further technical solution, in step 2, the ratio of tetrahydrofuran, product A, stearyl chloride, triethylamine, and 4-dimethylaminopyridine is 150 mL: 20.7 g: 30.2 g: 10.2 g: 0.6 g.

[0012] As a further technical solution, the ratio of the amount of sodium hypochlorite solution and product B in step 3 is 90 mL:47.3 g.

[0013] From the preparation process point of view: in step 1 of the present invention, p-hydroxybenzaldehyde reacts with biuret to obtain product A, the hydroxyl group at one end of product A can react with stearyl chloride to obtain product B, and finally product B is chlorinated to obtain a chloramine antibacterial agent.

[0014] From the performance of chloramine antibacterial agent: chloramine antibacterial agent contains three chloramine antibacterial components, which can release active chlorine (Cl + ) and hypochlorous acid (HOCl), destroying the cell structure and biomolecules of microorganisms to achieve broad-spectrum sterilization. Because the antibacterial agent also contains nano zinc oxide, the Zn released by nano zinc oxide 2+ It adsorbs on the bacterial cell membrane (negatively charged phospholipid bilayer), neutralizes the surface charge, destroys the stability of the bacterial membrane, and can also combine with -SH, -COOH and other groups in the membrane protein to cause protein denaturation, thereby playing an antibacterial role. Therefore, chloramine antibacterial agent can play a synergistic role with nano zinc oxide to greatly improve the antibacterial properties of the membrane. Finally, by introducing a long carbon chain of heptadecanyl into the chloramine antibacterial agent, this group has a long chain and good flexibility, which not only improves the flexibility of the membrane, but its higher hydrophobicity can also improve the compatibility of the chloramine antibacterial agent with the polyester matrix, making the chloramine antibacterial agent more stable and prolonging the antibacterial effect.

[0015] Beneficial effects of the present invention: Advantage 1: By adding nucleating agents such as sodium benzoate and sorbitol derivatives, the uniform crystallization of PET resin can be promoted, the formation of large-sized grains can be reduced, and the haze can be significantly reduced to meet the stringent transparency requirements of high-end optical display fields. Advantage 2: Self-made chloramine antibacterial agent, which can not only work synergistically with nano zinc oxide to improve the antibacterial property of the film, but also enhance the flexibility of the film, and has good compatibility with the PET matrix, delaying the migration of antibacterial components and prolonging the antibacterial effect; Advantage 3: The addition of anti-blocking agent can improve the surface smoothness and processability of the film; Therefore, the present invention solves the problem that traditional BOPET films cannot balance transparency, antibacterial properties and flexibility. It is suitable for high-end markets with strict requirements on optical and hygienic properties, and has important application value in the field of polyester film technology. DETAILED DESCRIPTION

[0016] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0017] 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.

[0018] Example 1 Preparation of chloramine antibacterial agent: Step 1: In a three-necked round-bottom flask, 95.1 g of hydrochloric acid (mass fraction 37%), 12.2 g of p-hydroxybenzaldehyde, and 10.3 g of biuret were added in sequence. The mixture was stirred mechanically at room temperature for 8 h. After the reaction was completed, ice water was added, and the mixture was washed with distilled water until the pH was ≈ 5. The mixture was filtered, dried, and recrystallized to obtain product A. Step 2: In a three-necked round-bottom flask, 150 mL of tetrahydrofuran, 20.7 g of product A, and 30.2 g of stearoyl chloride were added in sequence, stirred and mixed, and then 10.2 g of triethylamine and 0.6 g of 4-dimethylaminopyridine were added as catalysts. After stirring evenly, the mixture was heated to 40 ° C. At this temperature, the reaction was kept warm for 6 hours. After the reaction was completed, the solvent was removed by rotary evaporation, and the product B was recrystallized using dichloromethane. Step 3: In a three-necked round-bottom flask, 90 mL of sodium hypochlorite solution (mass fraction 12%) and 47.3 g of product B were added in sequence. The mixture was mechanically stirred at room temperature for 2 h. Since the reaction process was exothermic, no heating was required. After the reaction was completed, the solvent was removed by rotary evaporation, and the mixture was purified by column chromatography. Finally, the mixture was vacuum dried at 60 ° C to obtain a chloramine antibacterial agent.

[0019] Example 2 Preparation of chloramine antibacterial agent: Step 1: In a three-necked round-bottom flask, 190.2 g of hydrochloric acid (mass fraction 37%), 24.4 g of p-hydroxybenzaldehyde, and 20.6 g of biuret were added in sequence. The mixture was stirred mechanically at room temperature for 12 h. After the reaction was complete, ice water was added, and the mixture was washed with distilled water until the pH was ≈ 5. The mixture was filtered, dried, and recrystallized to obtain product A. Step 2: In a three-necked round-bottom flask, 300 mL of tetrahydrofuran, 41.4 g of product A, and 60.4 g of stearoyl chloride were added in sequence, stirred and mixed, and then 20.4 g of triethylamine and 1.2 g of 4-dimethylaminopyridine were added as catalysts. After stirring evenly, the mixture was heated to 60 ° C. At this temperature, the reaction was kept warm for 8 hours. After the reaction was completed, the solvent was removed by rotary evaporation, and the mixture was recrystallized from dichloromethane to obtain product B; Step 3: In a three-necked round-bottom flask, add 180 mL of sodium hypochlorite solution (mass fraction 12%) and 94.6 g of product B in sequence, and react with mechanical stirring at room temperature for 4 hours. Since the reaction process is exothermic, no heating is required. After the reaction is completed, the solvent is removed by rotary evaporation, and the product is purified by column chromatography. Finally, it is vacuum dried at 70 ° C to obtain a chloramine antibacterial agent.

[0020] Example 3 Preparation of high-transmittance and low-fog BOPET film: S1. Now vacuum dry the polyethylene terephthalate resin at 100°C for 4 hours, and control the moisture content to ≤50ppm to prevent hydrolysis and degradation during melt processing; S2. Mix 73 g of dried polyethylene terephthalate resin, 0.5 g of sodium benzoate, 1 g of erucamide, and 1.2 g of triphenyl phosphite to obtain a substrate layer raw material; S3, 67g of dried polyethylene terephthalate resin, 1g of nano zinc oxide and 2g of the chloramine antibacterial agent prepared in Example 1 were mixed to obtain a functional surface layer raw material; S4. The base material and the functional surface layer raw material are added to a twin-screw extruder for melting, and co-extruded through a co-extrusion die head at a ratio of 90:10. After rapid cooling, the film is biaxially stretched and heat-set, and then wound to obtain a high-transmittance, low-fog BOPET film.

[0021] Example 4 Preparation of high-transmittance and low-fog BOPET film: S1. Now vacuum dry the polyethylene terephthalate resin at 120°C for 6 hours, and control the moisture content to ≤50ppm to prevent hydrolysis and degradation during melt processing; S2. Mix 79 g of dried polyethylene terephthalate resin, 0.7 g of sorbitol derivative (DBS), 1.5 g of oleamide, and 2.0 g of tris(2,4-di-tert-butylphenyl) phosphite to obtain a substrate layer raw material; S3, 73g of dried polyethylene terephthalate resin, 2g of nano zinc oxide and 4g of the chloramine antibacterial agent prepared in Example 1 were mixed to obtain a functional surface layer raw material; S4. The base material and the functional surface layer raw material are added to a twin-screw extruder for melting, and co-extruded through a co-extrusion die head at a ratio of 85:15. After rapid cooling, the film is biaxially stretched and heat-set, and then wound to obtain a high-transmittance, low-fog BOPET film.

[0022] Example 5 Preparation of high-transmittance and low-fog BOPET film: S1. Now vacuum dry the polyethylene terephthalate resin at 120°C for 6 hours, and control the moisture content to ≤50ppm to prevent hydrolysis and degradation during melt processing; S2. 85 g of dried polyethylene terephthalate resin, 0.9 g of sorbitol derivative (DBS), 2 g of stearic acid amide, and 2.8 g of tris(nonylphenyl) phosphite were mixed to obtain a substrate layer raw material; S3, 79g of dried polyethylene terephthalate resin, 3g of nano zinc oxide and 6g of the chloramine antibacterial agent prepared in Example 1 were mixed to obtain a functional surface layer raw material; S4. The base material and the functional surface layer raw material are added to a twin-screw extruder for melting, and co-extruded through a co-extrusion die head at a ratio of 80:20. After rapid cooling, the film is biaxially stretched and heat-set, and then wound to obtain a high-transmittance, low-fog BOPET film.

[0023] Comparative Example 1 9 g of chloramine-T was used as the antibacterial agent to replace the nano zinc oxide in Example 5 and the chloramine antibacterial agent prepared in Example 1. The remaining steps were the same as in Example 5 to prepare a BOPET film.

[0024] Comparative Example 2 BOPET film produced by Xiongxian Aote Packaging Materials Co., Ltd. is used.

[0025] The following performance tests were performed on Examples 3, 4, and 5 and Comparative Examples 1 and 2: The flexural modulus is measured according to ISO 178:2019. The higher the flexural modulus, the stronger the film rigidity and the less flexible it is. Determine the light transmittance and haze according to GB / T 2410-2008 standard; The antibacterial properties were determined using the GB / T 31402-2015 standard and Escherichia coli (ATCC 8739) and Staphylococcus aureus (ATCC6538). The BOPET films of Examples 3, 4, 5 and Comparative Example 1 were washed 30 times and then tested for antibacterial properties using the same standard. As can be seen from the above table, after the antibacterial agent is added, the antibacterial properties and flexibility of the embodiments of the present invention are higher than those of the control example, and the transparency of the film is less affected. Moreover, after washing with water 30 times, the antibacterial properties remain stable and the antibacterial life is longer. Therefore, the present invention is suitable for high-end markets with strict requirements on optical and hygienic properties, and has important application value in the field of polyester film technology.

[0026] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A high-transmittance, low-fog BOPET film comprising a substrate layer and a functional surface layer, characterized in that: The functional surface layer accounts for 10-20% of the total mass of the BOPET film and is composed of the following raw materials in parts by mass: 67-79 parts of polyethylene terephthalate resin and 3-9 parts of antibacterial agent.

2. The high-transmittance, low-fog BOPET film according to claim 1, characterized in that: The antibacterial agent is prepared by compounding nano zinc oxide and chloramine antibacterial agent in a mass ratio of 1:2; wherein the chloramine antibacterial agent is prepared by the following steps: Step 1: In a flask, hydrochloric acid, p-hydroxybenzaldehyde and biuret were added in sequence, and stirred at room temperature for 8-12 hours. After the reaction was completed, post-processing was performed to obtain product A; Step 2: In a flask, tetrahydrofuran, product A and stearoyl chloride were added in sequence, stirred and mixed, and then triethylamine and 4-dimethylaminopyridine were added. After stirring evenly, the mixture was reacted at 40-60°C for 6-8 hours. After the reaction was completed, the mixture was post-treated to obtain product B. Step 3: In a flask, add sodium hypochlorite solution and product B in sequence, and react with mechanical stirring at room temperature for 2-4 hours. After the reaction is completed, post-process and obtain a chloramine antibacterial agent.

3. The high-transmittance, low-fog BOPET film according to claim 2, characterized in that: In step 1, the ratio of hydrochloric acid, p-hydroxybenzaldehyde and biuret is 95.1g:12.2g:10.3g.

4. The high-transmittance, low-fog BOPET film according to claim 2, characterized in that: In step 2, the ratio of tetrahydrofuran, product A, stearyl chloride, triethylamine, and 4-dimethylaminopyridine is 150 mL: 20.7 g: 30.2 g: 10.2 g: 0.6 g.

5. The high-transmittance, low-fog BOPET film according to claim 2, characterized in that: In step 3, the ratio of sodium hypochlorite solution to product B is 90 mL:47.3 g.

6. The high-transmittance, low-fog BOPET film according to claim 1, characterized in that: The substrate layer accounts for 80-90% of the total mass of the BOPET film and is composed of the following raw materials in parts by mass: 73-85 parts of polyethylene terephthalate resin, 0.5-0.9 parts of nucleating agent, 1-2 parts of anti-blocking agent, and 1.2-2.8 parts of antioxidant.

7. The high-transmittance, low-fog BOPET film according to claim 6, characterized in that: The nucleating agent is one of sodium benzoate, aluminum p-tert-butylbenzoate and a sorbitol derivative.

8. The high-transmittance, low-fog BOPET film according to claim 6, characterized in that: The antioxidant is one of triphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite and tris(nonylphenyl) phosphite.

9. The high-transmittance, low-fog BOPET film according to claim 6, characterized in that: The anti-adhesive agent is one of erucamide, oleamide and stearamide.

Images