Preparation method of polyethylene film with long-acting anti-dripping function
By synthesizing a core-shell structured anti-drip agent in polyethylene film, and utilizing shell barrier regulation and core gradient release, the fogging problem of polyethylene film was solved, achieving long-lasting anti-fogging and high transparency effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YUNNAN UNIV
- Filing Date
- 2025-12-04
- Publication Date
- 2026-04-24
AI Technical Summary
Existing polyethylene films are prone to fogging when there are temperature changes, which leads to reduced transparency and light scattering, affecting their performance. Furthermore, existing antifogging agents have poor adhesion and uneven distribution, resulting in issues with antifogging durability and transparency.
Using Span 20 as a surfactant, an anti-dripping agent with a core-shell structure was synthesized through emulsion polymerization. By utilizing shell barrier regulation and core gradient release, the migration of the surfactant was controlled to achieve slow and controllable release. Furthermore, the distribution of the anti-dripping agent in polyethylene was improved through two blending processes.
It achieves long-lasting anti-drip function, improves the hydrophilicity and anti-fogging effect of polyethylene film, while maintaining good transparency and low fog level, thus extending the service life of anti-fogging film.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically, it relates to a method for preparing a polyethylene film with long-lasting anti-drip function. Background Technology
[0002] Fog easily forms on common solid substrates, such as eyeglasses, car windows, goggles, and agricultural greenhouse films. Its main causes are temperature variations and moisture accumulation. The resulting fog scatters light, reducing the effectiveness of light transmission and degrading the optical properties of the solid surface, thus affecting visibility and user experience. For example, water vapor condensing on the surface of agricultural greenhouse films can scorch crops and affect their growth; fogging on car windows can impair driver visibility and, in severe cases, lead to traffic accidents; fog on optical sensors or instruments can reduce the accuracy of spectrometers. Agricultural greenhouse films are typically made of hydrophobic materials (polyethylene, polyvinyl chloride, polyvinyl fluoride, etc.). Due to the low surface energy, hydrophobic surface, and lack of hydrophilic groups in these materials, condensate cannot spread evenly on the film surface. Instead, it forms discrete droplets that gradually accumulate and eventually drip due to gravity. The water droplets formed on the film scatter incident light, causing the light to deflect and reducing the film's transmittance. In addition, once water droplets form on the film surface, they not only increase the humidity inside the greenhouse and packaging, but also form a thermal resistance layer, causing uneven temperature distribution inside the greenhouse and packaging, which affects the growth cycle and quality of crops.
[0003] Polyethylene is the most common plastic packaging and agricultural greenhouse film material, characterized by high transparency, easy processing, and low price. However, polyethylene molecules have a non-polar structure and are hydrophobic. When the ambient temperature changes, the surface of polyethylene is prone to fogging, and poor anti-fogging effect affects the application of polyethylene materials. Therefore, developing a polyethylene film with long-lasting anti-drip function is of great significance.
[0004] Currently, domestic and international literature reports methods for improving the anti-fogging performance of polyethylene generally involve blending anti-fogging agents into polyethylene or coating them onto the film surface. While direct coating is simple to operate, the adhesion between the coating and the polyethylene film is weak, resulting in poor anti-fogging durability and limited application scenarios. In contrast, anti-fogging polyethylene films prepared by blending have a longer service life. However, there are few reports on anti-fogging films with encapsulated anti-fogging agents that have a slow-release effect. Furthermore, the uneven distribution of the anti-fogging agent during blending reduces the transparency of the polyethylene and causes a large number of crystal points to form on the film surface. It is necessary to further adjust the existing anti-fogging polyethylene film production process to solve the transparency and crystal point problems of anti-fogging polyethylene films. Summary of the Invention
[0005] To overcome the technical problems existing in the background art, this invention proposes a method for preparing a polyethylene film with long-lasting anti-drip function. Using Span 20 as a surfactant, an anti-drip agent with a core-shell structure is synthesized through emulsion polymerization. By controlling the barrier regulation of the shell layer and the gradient release of the core layer, the migration of the active agent in the system is controlled to achieve slow and controllable release, which has both long-lasting effect and stability, thus extending the service life of the anti-fog film. Through improved synthesis process and two blending, the distribution of the anti-drip agent in polyethylene is improved, and the transparency and crystal point problems of the anti-fog polyethylene film are solved.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: A method for preparing a polyethylene film with long-lasting anti-dripping function, the specific preparation steps are as follows: 1) Synthesis of long-lasting anti-drip agent core layer solution a. Mix the emulsifier and deionized water by ultrasonic vibration at room temperature and set aside. b. Add Span 20, acrylic compounds, and initiators to the aforementioned mixed solution, and disperse at high speed at room temperature for 10 min to obtain a pre-emulsion; c. After the preemulsion was stirred at high speed at 50 °C for 1 h, the temperature was raised to 75 °C and stirred at low speed for 2 h to obtain the core layer emulsion; d. Add an initiator aqueous solution to the core emulsion and continue emulsification for 15 min; 2) Synthetic long-lasting anti-drip agents a. After the core emulsion emulsification is completed, vinyl acetate and acrylate compounds are slowly dripped into the core solution using a peristaltic pump over 3 hours; b. After the addition is complete, stir the mixture at low speed at 75 °C for 2 h; c. After the reaction is complete, add an initiator and heat to 80 °C for 1 h to obtain a white emulsion; d. The emulsion was dried at 60 °C to obtain the long-lasting anti-drip agent BXY; 3) Preparation of polyethylene film Long-lasting anti-drip agent (BXY), low-density polyethylene (LDPE), C8 low-density polyethylene (C8 LDPE), and high-density polyethylene (HDPE) are mixed evenly in a certain proportion and then added to a single-screw extruder for melt blending to obtain an extrudate. The extrudate is then cut into granules by a granulator and the granules are slowly added to a single-screw blown film mill to obtain a long-lasting anti-drip polyethylene film.
[0007] Further, in step 1), the emulsifier is a compound of nonionic and anionic surfactants in a ratio of 3:2. The nonionic surfactant is one of fatty alcohol polyoxyethylene ether (MOA-5) and alkylphenol polyoxyethylene ether (OP-10); the anionic surfactant is one of sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS).
[0008] Further, in step 1), the acrylic compound is one of α-methacrylic acid (MAA), methyl methacrylate (MMA), and ethyl acrylate (EA).
[0009] Further, in step 1), the initiator is one of benzoyl peroxide (BPO), ammonium persulfate (APS), azobisisobutyronitrile (AIBN), and di-tert-butyl peroxide (DTBP).
[0010] Further, in step 2), the acrylate compound is one of n-butyl acrylate (BA), hydroxyethyl acrylate (HEA), acrylic acid (AA), and butyl methacrylate (MBA).
[0011] Furthermore, in step 3), the mass ratio of long-lasting anti-drip agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene is 85:6:9:5.
[0012] (1) The present invention uses Span 20 as a surfactant and synthesizes an anti-dripping agent with a core-shell structure through emulsion polymerization. By controlling the barrier regulation of the shell layer and the gradient release of the core layer, the migration of the surfactant in the system is controlled to achieve slow and controllable release, which has both long-lasting effect and stability, and extends the service life of the anti-fog film.
[0013] (2) By improving the synthesis process and double blending, the distribution of anti-dripping agent in polyethylene was improved, and the transparency and crystal point problems of anti-fog polyethylene film were solved. Attached Figure Description
[0014] Figure 1 This is a comparison diagram of the water contact angles of PE and polyethylene films from various embodiments of the present invention; Figure 2 This is a comparison chart of the light transmittance and haze of PE and polyethylene films from various embodiments of the present invention; Figure 3 This is a diagram showing the effect of accelerated anti-fogging test at 60 ℃. Detailed Implementation
[0015] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described. Example 1
[0016] Preparation of a polyethylene film with long-lasting anti-drip function: 1) Synthesis of core layer solution of long-lasting anti-drip agent 0.32 g MOA-5, 0.21 g SDS, and 136 g deionized water were ultrasonically mixed at room temperature and set aside. 9 g Span 20, 1.35 g MAA, and 0.009 g BPO were added to the above mixed solution and dispersed at high speed at room temperature for 10 min to obtain a pre-emulsion. The pre-emulsion was stirred at high speed at 50 °C for 1 h, then the temperature was increased to 75 °C and stirred at low speed for 2 h to obtain a core emulsion. 5 g KPS aqueous solution was added to the core emulsion, and the reaction was continued for 15 min.
[0017] 2) Synthesis of long-lasting anti-drip agents After the core emulsion emulsification was completed, 16.17 g VAc, 2.1 g BA, and 2.73 g HEA were weighed, mixed thoroughly, and then slowly added dropwise to the core emulsion using a peristaltic pump over 3 hours. After the addition was complete, the reaction system was stirred at low speed at 75 °C for 2 hours. After the reaction was completed, 5 g KPS aqueous solution was added, and the temperature was raised to 80 °C and kept at that temperature for 1 hour to obtain a white emulsion. The emulsion was dried at 60 °C to obtain the desired anti-drip agent.
[0018] 3) Preparation of long-lasting anti-drip polyethylene film Long-lasting anti-dripping agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene (mass ratio 85:6:9:5) were uniformly mixed and then added to a single-screw extruder. The extruder's four zones were set at 130, 135, 165, and 160°C, with a rotation speed of 35 rpm. The extrudate was melt-blended to obtain an extrudate, which was then granulated using a granulator. The resulting granules were slowly added to a single-screw blown film extruder (zones 1-12 were set at 135, 168, 170, 168, 135, 170, 170, 168, 170, 170, 160, and 160°C, with a screw rotation speed of 14.0 Hz and a traction speed of 5.0 Hz) to obtain the final product. Example 2
[0019] Preparation of a polyethylene film with long-lasting anti-drip function: 1) Synthesis of core layer solution of long-lasting anti-drip agent 0.65 g MOA-5, 0.43 g SDS, and 200 g deionized water were ultrasonically mixed at room temperature and set aside. 18 g Span 20, 1.35 g MAA, and 0.009 g BPO were added to the above mixed solution and dispersed at high speed at room temperature for 10 min to obtain a pre-emulsion. The pre-emulsion was stirred at high speed at 50 °C for 1 h, and then the temperature was increased to 75 °C and stirred at low speed for 2 h to obtain a core emulsion. 5 g KPS aqueous solution was added to the core emulsion, and the reaction was continued for 15 min.
[0020] 2) Synthesis of long-lasting anti-drip agents After the core emulsion emulsification was completed, 20.79 g VAc, 2.7 g BA, and 3.51 g HEA were weighed, mixed thoroughly, and then slowly added dropwise to the core emulsion using a peristaltic pump over 3 hours. After the addition was complete, the reaction system was stirred at low speed at 75 °C for 2 hours. After the reaction was completed, 5 g KPS aqueous solution was added, and the temperature was raised to 80 °C and kept at that temperature for 1 hour to obtain a white emulsion. The emulsion was dried at 60 °C to obtain the desired anti-dripping agent.
[0021] 3) Preparation of long-lasting anti-drip polyethylene film Long-lasting anti-dripping agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene (mass ratio 85:6:9:5) were uniformly mixed and then added to a single-screw extruder. The extruder's four zones were set at 130, 135, 165, and 160°C, with a rotation speed of 35 rpm. The extrudate was melt-blended to obtain an extrudate, which was then granulated using a granulator. The resulting granules were slowly added to a single-screw blown film extruder (zones 1-12 were set at 135, 168, 170, 168, 135, 170, 170, 168, 170, 170, 160, and 160°C, with a screw rotation speed of 14.0 Hz and a traction speed of 5.0 Hz) to obtain the final product. Example 3
[0022] Preparation of a polyethylene film with long-lasting anti-drip function: 1) Synthesis of core layer solution of long-lasting anti-drip agent 0.90 g MOA-5, 0.60 g SDS, and 225 g deionized water were ultrasonically mixed at room temperature and set aside. 25 g Span 20, 3.75 g MAA, and 0.025 g BPO were added to the above mixed solution and dispersed at high speed at room temperature for 10 min to obtain a pre-emulsion. The pre-emulsion was stirred at high speed at 50 °C for 1 h, and then the temperature was increased to 75 °C and stirred at low speed for 2 h to obtain a core emulsion. 5 g KPS aqueous solution was added to the core emulsion, and the reaction was continued for 15 min.
[0023] 2) Synthesis of long-lasting anti-drip agents After the core emulsion emulsification was completed, 19.25 g VAc, 2.5 g BA, and 3.25 g HEA were weighed, mixed evenly, and the solution was slowly added dropwise to the core emulsion using a peristaltic pump over 3 hours. After the addition was complete, the reaction system was stirred at low speed at 75 °C for 2 hours. After the reaction was completed, 5 g KPS aqueous solution was added, and the temperature was raised to 80 °C and kept at that temperature for 1 hour to obtain a white emulsion. The emulsion was dried at 60 °C to obtain the desired anti-drip agent.
[0024] 3) Preparation of long-lasting anti-drip polyethylene film Long-lasting anti-dripping agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene (mass ratio 85:6:9:5) were uniformly mixed and then added to a single-screw extruder. The extruder's four zones were set at 130, 135, 165, and 160°C, with a rotation speed of 35 rpm. The extrudate was melt-blended to obtain an extrudate, which was then granulated using a granulator. The resulting granules were slowly added to a single-screw blown film extruder (zones 1-12 were set at 135, 168, 170, 168, 135, 170, 170, 168, 170, 170, 160, and 160°C, with a screw rotation speed of 14.0 Hz and a traction speed of 5.0 Hz) to obtain the final product. Example 4
[0025] Preparation of a polyethylene film with long-lasting anti-drip function: 1) Synthesis of core layer solution of long-lasting anti-drip agent 0.90 g MOA-5, 0.60 g SDS, and 225 g deionized water were ultrasonically mixed at room temperature and set aside. 25 g Span 20, 3.75 g MAA, and 0.025 g BPO were added to the above mixed solution and dispersed at high speed at room temperature for 10 min to obtain a pre-emulsion. The pre-emulsion was stirred at high speed at 50 °C for 1 h, and then the temperature was increased to 75 °C and stirred at low speed for 2 h to obtain a core emulsion. 5 g KPS aqueous solution was added to the core emulsion, and the reaction was continued for 15 min.
[0026] 2) Synthesis of long-lasting anti-drip agents After the core emulsion emulsification was completed, 12.86 g VAc, 1.67 g BA, and 2.17 g HEA were weighed, mixed thoroughly, and then slowly added dropwise to the core emulsion using a peristaltic pump over 3 hours. After the addition was complete, the reaction system was stirred at low speed at 75 °C for 2 hours. After the reaction was completed, 5 g KPS aqueous solution was added, and the temperature was raised to 80 °C and kept at that temperature for 1 hour to obtain a white emulsion. The emulsion was dried at 60 °C to obtain the desired anti-dripping agent.
[0027] 3) Preparation of long-lasting anti-drip polyethylene film Long-lasting anti-dripping agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene (mass ratio 85:6:9:5) were uniformly mixed and then added to a single-screw extruder. The extruder's four zones were set at 130, 135, 165, and 160°C, with a rotation speed of 35 rpm. The extrudate was melt-blended to obtain an extrudate, which was then granulated using a granulator. The resulting granules were slowly added to a single-screw blown film extruder (zones 1-12 were set at 135, 168, 170, 168, 135, 170, 170, 168, 170, 170, 160, and 160°C, with a screw rotation speed of 14.0 Hz and a traction speed of 5.0 Hz) to obtain the final product. Experimental Analysis
[0028] The polyethylene films prepared in Examples 1-4 above were subjected to water contact angle tests, such as... Figure 1 As shown, the water contact angle of the polyethylene film prepared by the present invention is significantly lower than that of pure polyethylene film (PE), indicating that the anti-dripping agent of the present invention is well dispersed in polyethylene and exhibits good hydrophilicity.
[0029] The transmittance and haze of the polyethylene films prepared in Examples 1-4 were tested, and the results are as follows: Figure 2 As shown, compared with pure polyethylene film (PE), the polyethylene film of the present invention has a lower light transmittance and a higher haze, but still has a high light transmittance of 92%, which meets the national usage standards.
[0030] The polyethylene films prepared in Examples 1-4 above were subjected to an accelerated anti-fogging test at 60 °C hot water, and the results are as follows: Figure 3 As shown in Figures, (a) is the pure PE group, (b) is Example 1, (c) is Example 2, (d) is Example 3, (e) is Example 4, (i) is a photograph at 0 min, and (ii) is a photograph at the initial drop. The photographs show that before the anti-fogging experiment, the polyethylene film covering the beaker was transparent and fog-free. When the water in the beaker was replaced with hot water at 60 °C, the pure polyethylene film quickly fogged up (approximately 3 seconds), indicating that the pure polyethylene film had no anti-fogging ability. As the test time increased, the pure polyethylene film was completely covered by fog, making it impossible to distinguish the solution in the beaker, while in the embodiments of this invention, the text on the bottom of the beaker was still relatively visible.
[0031] The aforementioned experimental data show that, compared with pure PE film, PE film with added long-lasting anti-drip agent has significantly improved hydrophilicity and anti-fogging effect, while maintaining good transparency and low haze.
[0032] In summary, this invention uses Span 20 as a surfactant to synthesize an anti-dripping agent with a core-shell structure through emulsion polymerization. By controlling the barrier regulation of the shell layer and the gradient release of the core layer, the migration of the surfactant in the system is controlled to achieve slow and controllable release, which has both long-lasting effect and stability, thus extending the service life of the anti-fog film. Through improved synthesis process and two blending processes, the distribution of the anti-dripping agent in polyethylene is improved, solving the problems of transparency and crystal point in anti-fog polyethylene film.
[0033] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.
Claims
1. A method for preparing a polyethylene film with long-lasting anti-drip function, characterized in that: The specific preparation steps are as follows: 1) Synthesis of long-lasting anti-drip agent core layer solution a. Mix the emulsifier and deionized water by ultrasonic vibration at room temperature and set aside. b. Add Span 20, acrylic compounds, and initiators to the aforementioned mixed solution, and disperse at high speed at room temperature for 10 min to obtain a pre-emulsion; c. After the preemulsion was stirred at high speed at 50 °C for 1 h, the temperature was raised to 75 °C and stirred at low speed for 2 h to obtain the core layer emulsion; d. Add an initiator aqueous solution to the core emulsion and continue emulsification for 15 min; 2) Synthetic long-lasting anti-drip agents a. After the core emulsion emulsification is completed, vinyl acetate and acrylate compounds are slowly dripped into the core solution using a peristaltic pump over 3 hours; b. After the addition is complete, stir the mixture at low speed at 75 °C for 2 h. c. After the reaction is complete, add an initiator and heat to 80 °C for 1 h to obtain a white emulsion; d. The emulsion was dried at 60 °C to obtain the long-lasting anti-drip agent BXY; 3) Preparation of polyethylene film Long-lasting anti-dripping agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene are mixed evenly in a certain proportion and then added to a single-screw extruder for melt blending to obtain an extrudate. The extrudate is then cut into granules by a granulator and the granules are slowly added to a single-screw blown film mill to obtain a long-lasting anti-dripping polyethylene film.
2. The method for preparing a polyethylene film with long-lasting anti-drip function according to claim 1, characterized in that: In step 1), the emulsifier is a compound of nonionic and anionic surfactants in a ratio of 3:
2. The nonionic surfactant is one of fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether; the anionic surfactant is one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.
3. The method for preparing a polyethylene film with long-lasting anti-drip function according to claim 1, characterized in that: In step 1), the acrylic compound is one of α-methacrylic acid, methyl methacrylate, and ethyl acrylate.
4. The method for preparing a polyethylene film with long-lasting anti-drip function according to claim 1, characterized in that: In step 1), the initiator is one of benzoyl peroxide, ammonium persulfate, azobisisobutyronitrile, and di-tert-butyl peroxide.
5. The method for preparing a polyethylene film with long-lasting anti-drip function according to claim 1, characterized in that: In step 2), the acrylate compound is one of n-butyl acrylate, hydroxyethyl acrylate, acrylic acid, and butyl methacrylate.
6. The method for preparing a polyethylene film with long-lasting anti-drip function according to claim 1, characterized in that: In step 3), the mass ratio of long-lasting anti-dripping agent, low-density polyethylene, C8 low-density polyethylene, and high-density polyethylene is 85:6:9:5.