PVC Shrink Films is a plastic film processed by a special process using PVC resin as the main raw material, which is characterized by heat shrinkage.
Shrink film has a place in the field of packaging materials because of its "heat shrinkage" characteristic of polymer materials. PVC shrink film has good shrinkage, moisture resistance, high toughness, good transparency, etc., and simple packaging technology, beautiful appearance, puncture resistance, can also increase the added value of packaging products, cost-effective, widely used in doors and windows, aluminum materials, plaster lines, stainless steel, chemical products, electronic components and ceramics, metal accessories and other packaging.
PVC Shrink Films
PVC shrink film is made after secondary inflation and rapid cooling, so what principle does it use?
The linear polymer long chain of PVC shrink film is usually in a curled state. When the polymer is heat-melted in a highly elastic state, the polymer chain is stretched and aligned under the action of external force, and then rapidly cooled, the orientation state of the polymer chain is frozen. When the temperature rises again, the polymer chain tends to a stable state, curls, and it appears to shrink in a macroscopic view. From the principle of shrinkage, there is no chemical change, so it is called "physical reduction".
Commonly used PVC shrink film is made of polyvinyl chloride resin and dozens of auxiliary materials after being blown up. It has the characteristics of good transparency, easy shrinkage, high strength, shrinkage rate can be freely adjusted according to user needs, and strong operability. But we need to know how to judge the quality of PVC shrink film, then from what aspects to judge the quality of PVC shrink film? The suppliers of Environmentally Friendly PLA Shrink Film will come to tell you.
The first thing to look at is the transparency and gloss of the PVC shrink film. High-quality PVC shrink film has good transparency and gloss. If you look in the sun, there are not many impurities;
Then, the choice of PVC resin model is the key to the production of PVC shrink film. It should choose a resin with good comprehensive properties and easy to plasticize. As far as the molecular weight of resin is concerned, generally the molecular weight increases, the product's thermal stability, blown film calenderability, tensile strength, impact strength and other properties will be improved to varying degrees, and the physical properties of plastic products can also be improved. However, the molecular weight is not as large as possible. If the molecular weight is too large, the plasticizing temperature will be increased, the fluidity and ductility of the resin will be deteriorated, and it will cause difficulties to the thermal stabilization system and secondary inflation;
Third: A good quality shrink film shrinks quickly when it is packaged by a shrink film. On the contrary, a poor quality shrink film does not shrink well, or it needs two or three heat shrinks to complete the shrinking process;
Fourth: sealing performance. When the shrink film passes through the shrink film packaging machine, the PVC heat shrink film will break, wrinkle or have small holes, which is caused by poor sealing performance. High-quality PVC shrink film has good sealing performance. After the heat shrinking process is completed, it is very beautiful and can really achieve the expected shrinkage effect;
Fifth: puncture resistance, that is, the shrink film has the protective effect we want during product transportation. High-quality shrink film has high puncture resistance and is not easy to puncture;
Sixth: Strong shrink memory function and good shrink tightness, which are reflected in the protection of the product when the entire product and parts are shrink-wrapped, and will not form scattered or incomplete packaging.
The above is how to judge the quality of PVC shrink film introduced by Multi-purpose Shrink Film Manufacturer. I hope it can help everyone.