Heat Shrink Film Packaging Machine Overview
Heat shrinkable film is mainly used for labeling, heat shrink packaging or wrapping film. The polymer resins suitable for preparing the heat shrinkable film are mainly PVC, PE, PS, PET, and the like. After the film is preheated, it is stretched and cooled and set (as long as it is not subjected to heat setting treatment) to obtain a heat shrinkable film. The resin slab is stretched in the transverse direction and the longitudinal direction near the Tf of the resin, and then quenched to freeze the resin molecular chain in an oriented state to form a heat shrinkable film. From the raw material to the formation of the heat shrinkable film is a process of entropy reduction. The thermodynamic state of the heat shrinkable film is unstable. When the shrink film is subjected to heat treatment, the already oriented molecular chain will quickly return to the random coil (distorted state). The film shrinks. The use of this feature of the heat shrinkable film allows the preparation of labels for shaped bottles.
The parameters for measuring the heat shrinkable film are shrinkage, shrinkage, and shrinkage. Shenzhen Huale Plastic Products Co., Ltd. said that from the above three parameters, in order to obtain a film with a high shrinkage rate, it is necessary to use a polymer resin with low crystallinity or low crystallinity. Although the amorphous resin is oriented after the biaxial orientation, the crystallization does not occur. When the secondary preheating is received, all the oriented chains can shrink, and only the uncrystallized oriented molecular chains are heated. Low processing temperature, short processing time) shrinks; and the molecular chain of oriented crystals needs to break the crystal lattice to achieve shrinkage, which requires raising the temperature to near the melting point and the relaxation time of the molecular chain is longer, and this It is impossible to achieve during the use of shrink film.
For the heat shrinkable film prepared from the same material, the higher the proportion of the amorphous region, the larger the shrinkage rate and the greater the shrinkage force. The relatively large heat shrinkable film of the amorphous region has a lower shrinkage temperature.
The parameters for measuring the heat shrinkable film are shrinkage, shrinkage, and shrinkage. Shenzhen Huale Plastic Products Co., Ltd. said that from the above three parameters, in order to obtain a film with a high shrinkage rate, it is necessary to use a polymer resin with low crystallinity or low crystallinity. Although the amorphous resin is oriented after the biaxial orientation, the crystallization does not occur. When the secondary preheating is received, all the oriented chains can shrink, and only the uncrystallized oriented molecular chains are heated. Low processing temperature, short processing time) shrinks; and the molecular chain of oriented crystals needs to break the crystal lattice to achieve shrinkage, which requires raising the temperature to near the melting point and the relaxation time of the molecular chain is longer, and this It is impossible to achieve during the use of shrink film.
For the heat shrinkable film prepared from the same material, the higher the proportion of the amorphous region, the larger the shrinkage rate and the greater the shrinkage force. The relatively large heat shrinkable film of the amorphous region has a lower shrinkage temperature.