Heat shrinkable film has good heat sealing performance
The production principle of pvc heat shrinkable film The stable state of polymer chain tends to curl state. When the polymer is heated and melted in a highly elastic state, the stretching orientation of the polymer chain is straightened under the action of external force, and after the rapid cooling reaches the glass transition temperature, the orientation state of the polymer chain is frozen. When the temperature rises again, the polymer chain tends to be in a stable state, curls occur, and shrinks macroscopically. From the perspective of its shrinkage principle, there is no chemical change, so it is called "physical reducibility". The PVC heat-shrinkable film produced by blow molding uses the above principles and is produced after two blows and rapid cooling. PVC heat shrinkable film is a new type of packaging material that is currently popular internationally. It has good transparency, good toughness, impact resistance, corrosion resistance, and low water vapor transmission. There is also an ideal shrinkage rate. When the film is exposed to a certain temperature, it will automatically shrink to tightly wrap the goods, thereby protecting the goods, and also play a role in preventing moisture, mildew, rust, pollution, injury and theft. Product storage stability, simple packaging technology and equipment, easy to realize automatic shrink packaging. PVC heat shrinkable film is used for the sales and transportation of various products. Its main function is to stabilize, cover and protect the product. The shrink film must have high puncture resistance, good shrinkage and a certain shrinkage stress. During the shrinking process , The film can not produce holes. Because pvc heat shrinkable film is often suitable for outdoor use, it is necessary to add UV anti-ultraviolet agent.
High transparency is conducive to the identification of goods; high longitudinal elongation is conducive to pre-stretching and saving material consumption; good puncture performance and transverse tearing strength allow the wrapping film to encounter sharp corners of the goods at high stretch magnification Or the side does not break; the high yield point makes the packaged goods more tight. Stretch film is characterized by good cushioning strength, good puncture and tear resistance, thin thickness, and good performance and price ratio. It has high tensile strength, tear resistance, transparency and good retraction force. The pre-stretching ratio is 400%. It can be assembled, waterproof, dustproof, scattered and anti-theft. Used in pallet wrapping and other winding packaging, widely used in foreign trade export, bottle making, paper making, hardware and electrical appliances, plastics, chemicals, building materials, agricultural products, food and other industries. Heat-shrinkable film first appeared in Germany during the Second World War. PVDC was used to pack weapons after bidirectional stretching to prevent rust. Therefore, heat shrinkable film has been used in industrial packaging since the beginning of industrial production, and then heat shrinkable film has been used for food packaging.
The heat shrinkable film has the characteristics of non-toxic and environmental protection, high transparency, large shrinkage, good heat sealing performance, high surface gloss, good toughness, high tear resistance, uniform heat shrinkage and suitable for automatic high-speed packaging. It is traditional PVC The best replacement product for heat shrinkable film, POF C-3 is currently widely used in the outer packaging of food, medicine, beverages, wine, electrical products, electronic products, toys, daily necessities and other products.
The multi-layer co-extrusion film technology of heat-shrinkable film manufacturers uses more than three extruders to extrude several different resins and enter the die for compound co-extrusion to obtain film products with certain functions, including high-barrier packaging films , Shrink film, vacuum cling film, geomembrane, etc. It can be widely used in food, medicine, daily chemical product packaging, electronics industry, metal industry and other fields. Geomembrane can be used in water conservancy engineering, environmental engineering and other fields. The multilayer film improves the barrier properties to oxygen and fragrance, composite peel strength, environmental resistance and fresh-keeping storage period. It also realizes the functions of various materials, reduces the cost, and replaces many dry materials with suitable secondary processing. The packaging market is dominated by type composite, and there is no residual pollution of adhesive.