In Depth Analysis: Key Links in The Production Process Of PVC Cling Film

In daily life and business, cling film is an important tool for ensuring food freshness and extending shelf life. PVC cling film, with its unique properties, has occupied a certain market share. To gain a deeper understanding of PVC cling film, it is necessary to explore the key links in its production process, which not only determine the quality of the product, but also affect its competitiveness in the market.
1, Strict screening of raw materials
The main raw material for PVC cling film is polyvinyl chloride (PVC) resin, which is the foundation of the entire production process. When selecting PVC resin, manufacturers will strictly control its purity, molecular weight distribution, particle morphology, and other indicators. High purity PVC resin can ensure good stability and safety of cling film, reducing the potential risk of impurities contaminating food. The appropriate molecular weight distribution determines the physical properties of cling film, such as tensile strength, flexibility, and transparency. PVC resin with uniform molecular weight distribution can prevent the plastic wrap from breaking easily during stretching, while ensuring its good flexibility, making it easy to wrap various shapes of food.
In addition to PVC resin, a series of additives need to be added. Plasticizers are one of the most crucial ones, as they can increase the flexibility and plasticity of PVC, making cling film easier to process and use. Commonly used plasticizers include phthalates, but due to the potential harm of some phthalates to human health, some manufacturers are now developing and using more environmentally friendly and safe new plasticizers. Stabilizers are also indispensable additives, which can prevent PVC from degrading due to factors such as heat and light during processing and use, ensuring the stability of the performance of cling film.
2, Ingredients and Mixing Process
Accurate ingredients and thorough mixing are key steps in ensuring the consistency of PVC cling film quality. During the ingredient preparation process, it is necessary to accurately calculate the ratio of PVC resin and various additives based on the performance requirements of the product. Any deviation in the composition of the plastic wrap can lead to performance issues, such as excessive addition of plasticizers causing the wrap to become too soft and lose its expected strength; Insufficient stabilizer addition may cause the cling film to age and become brittle during storage.
The mixing process is usually carried out in a high-speed mixer, where the PVC resin and additives are thoroughly and uniformly mixed by a high-speed rotating stirring blade. During the mixing process, it is also necessary to control the temperature and time to ensure that various components can fully blend together. A good mixing effect can ensure that the performance of various parts of the cling film is uniform and consistent in the subsequent processing, avoiding the occurrence of significant differences in local performance.
3, Extrusion molding process
Extrusion molding is a key step in processing mixed materials into cling film. The preheated material is fed into the extruder, and under the push of the screw, the material is gradually compacted, melted, and extruded into thin sheets inside the barrel. The temperature control of the extruder is crucial. If the temperature is too high, the material may decompose, leading to a decrease in the performance of the cling film; If the temperature is too low, the material will melt unevenly, affecting the quality of the cling film.
The head of the extruder is a key component that determines the thickness and width of the cling film. By adjusting the die gap and extrusion speed of the machine head, the thickness and width of the cling film can be precisely controlled. In order to ensure the uniformity of the thickness of the cling film, a thickness control system needs to be installed at the machine head to monitor and adjust the thickness of the cling film in real time.
4, Cooling and shaping
The high-temperature cling film extruded from the extruder head needs to be quickly cooled and shaped to fix its shape and size. The commonly used cooling method is contact cooling through a cooling roller, which is filled with cooling water inside to quickly remove the heat from the cling film and cool it down quickly. During the cooling process, it is also necessary to stretch the cling film appropriately to improve its tensile strength and flexibility.
After cooling and shaping, the cling film needs to undergo surface treatment to improve its surface properties, such as increasing its self adhesiveness to better adhere to the surface of food. Common surface treatment methods include corona treatment, coating treatment, etc.
5, Quality Inspection and Packaging
In the final stage of PVC cling film production, strict quality testing is required for the product. The testing items include thickness uniformity, tensile strength, elongation at break, transparency, self adhesiveness, etc. Only products that meet quality standards in all aspects can enter the market for sale.
PVC cling film that has passed quality inspection will be packaged. The packaging forms usually include roll up and boxed packaging, which will indicate the specifications, ingredients, usage methods, shelf life, and other information of the product, making it convenient for consumers to use and understand the product.
The production process of PVC cling film involves multiple key links, each of which has a significant impact on the quality and performance of the product. With the continuous advancement of technology and the increasing demand for product quality from consumers, the production process of PVC cling film is also constantly innovating and improving to produce higher quality, safer, and more environmentally friendly products that meet market demand.