Processing and application of heat shrinkable film

The production process is to dry the PET copolymer resin first, taking the production process of BOPET film as an example. Then it is added to the extruder and melted and extruded, and the piece is cast through the cold drum of the die, and then the cast piece is heated to an appropriate temperature range above the glass transition temperature and below the melting temperature, and under the action of external force, one-way or Stretching in two-way multiples usually requires a stretch of 3.5 to 4.0 times in the transverse direction. The PET macromolecular chain is oriented in the direction of external force by stretching, and then it is cooled and shaped, so that the oriented PET molecular structure is frozen and shaped. The high elastic deformation under this external force has the memory effect of thermal shrinkage. When the film with memory effect is reheated to above the stretching temperature, the frozen macromolecular orientation structure begins to relax, which is macroscopically expressed as PET film. shrink. It is worth mentioning that the thermal shrinkage of this PET film is mainly contributed by the oriented amorphous part. This is why the copolymerized modified amorphous PET film (APET or PETG has a much larger heat shrinkage rate than ordinary crystalline PET film. Therefore, by increasing the orientation of the amorphous area in the film, the heat shrinkage of the film can be greatly improved. As mentioned above, the heat shrinkage rate of ordinary polyester film is only below 30%, while the heat shrinkage rate of copolymer modified polyester can be as high as 70%. With low density polyethylene (LDPE), linear Low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) are used as raw materials to prepare heat shrinkable film by blow molding. The raw material formula, mold inflation ratio, blown film machine draft ratio, extrusion temperature and The influence of bubble cooling time and other factors on the mechanical properties and transparency of polyethylene heat shrinkable film. The results show that: compared with HDPE, the heat shrinkable film produced by adding LLDPE raw materials in the formula has better overall performance; as the unit runs As the draft ratio increases, the tensile properties, shrinkage rate and light transmittance of PE heat shrinkable film all show an upward trend; with the increase of mold expansion ratio, the longitudinal shrinkage rate of PE heat shrinkable film decreases, and the transverse shrinkage rate And light transmittance increase; with the increase of extruder process temperature, the longitudinal and transverse shrinkage rates of PE heat shrinkable film increase at the same time; with the extension of the bubble cooling time, the longitudinal and transverse shrinkage rates of PE heat shrinkable film And the light transmittance are decreased. When heated (above the glass transition temperature), the heat shrinkable plastic film is required to be stable at room temperature. It is ideal for heat shrinkage of more than 50% in one direction. The characteristics of heat shrinkable plastic film packaging It is skinny and transparent, reflecting the image of the product; tightly packed, good dispersion resistance; rainproof, moisture-proof, and mildew-proof; non-recoverable, with anti-counterfeiting function. Heat shrinkable plastic film is often used in convenience foods, beverages, electronic appliances, and metals The packaging of products, especially shrink labels is its main application field. In addition to shrink labels, heat shrinkable plastic films are used. Heat shrinkable films | Fully automatic packaging machine film manufacturers-How many plastic bags affect the heat seal strength of pof heat shrinkable film A factor, POF heat shrinkable film and PE, PVC shrink film performance comparison