Heat shrinkable film production process
The product has good storage and transportation stability, and the packaging process and equipment are relatively simple, which is convenient for implementing active shrink packaging. At present, the prevailing packaging in the shopping mall is mainly made of plastic and paper. The blow molding industry, which is mainly composed of plastic blown film machine, has a large proportion in the shopping mall, but with the increasingly strict requirements on the paper industry, the new environmental protection and energy saving The goal has raised the threshold for the paper industry, resulting in the expansion of paper packaging malls and rising prices. This makes the proportion of heat shrinkable film plastic packaging in the mall correspondingly increased, stimulating the development of the film blowing machine manufacturing machinery industry.
Although the heat shrinkable film has excellent quality assurance, some people may say that PVC is a chemical product after all, it is not comparable to the material, it can not eliminate the toxicity and odor, and it will inevitably cause harm to the environment. This is not the case. This is because the raw materials for the production of PVC heat shrinkable film are specially refined and the toxic substances are extracted. Therefore, PVC is tasteless and has no irritation to human skin or respiratory system. For those who are interested in wood and paint. For those who are allergic, furniture or kitchen utensils wrapped in PVC heat shrinkable film are very suitable. By using a PVC heat shrinkable film as a decorative film, it is possible to use a medium-density board, a particle board, a plywood, and a fiberboard in a large amount, thereby reducing the amount of wood used, thereby reducing damage to forests and the environment. From this perspective, the heat shrinkable film has made a great contribution to the protection of the ecological environment.
The choice of heat shrink film customers usually first consider the specific selection mode from the cost. Heat shrinkable packaging and laminated film can usually achieve the same packaging effect, then how to decide which packaging film to use? In general, the main differences are the requirements for the packaging pattern, the frequency of packaging required, the shelf life requirements, and the physical properties of the packaging itself such as liquid, powder, granules, solids, squares, and the like. The following guidelines help customers to select the right packaging materials: the size of the food factory; whether the service is industrial or retail; adjustment requirements; shelf life requirements; anti-abuse requirements; product shape; whether it is used for preservation, freezing or No other environmental requirements; the consistency of the packaging production company and the customer culture.
The heat shrinkable film production process is to dry the PET copolymer resin first, taking the production process of the BOPET film as an example. Then, it is added to the extruder for melt extrusion, cold drum casting through a die, and then the slab is heated to a temperature above the glass transition temperature, below a melting temperature, and under the action of an external force, one-way or Stretching in a two-fold multiple is usually required to perform a stretch of 3.5 to 4.0 times in the lateral direction. The PET macromolecular chain is oriented in the direction of the external force by stretching, and then cooled and shaped to "freeze" the oriented PET molecular structure. The high elastic deformation under the action of external force has a heat-shrinking memory effect. When the film with the "memory effect" is reheated above the stretching temperature, the macromolecular orientation structure is frozen and begins to relax. PET film shrinkage. It is worth mentioning that the PET film shrinkage is mainly contributed by the amorphous part of the orientation. This is why the copolymerized modified amorphous PET film (APET or PETG is heat shrinkable than the ordinary crystalline PET film). Therefore, the purpose of greatly increasing the heat shrinkage rate of the film can be achieved by increasing the orientation of the amorphous region in the film. As described above, the heat shrinkage rate of the ordinary polyester film is only 30% or less, and copolymerization. The modified polyester has a heat shrinkage rate of up to 70% or more.
Although the heat shrinkable film has excellent quality assurance, some people may say that PVC is a chemical product after all, it is not comparable to the material, it can not eliminate the toxicity and odor, and it will inevitably cause harm to the environment. This is not the case. This is because the raw materials for the production of PVC heat shrinkable film are specially refined and the toxic substances are extracted. Therefore, PVC is tasteless and has no irritation to human skin or respiratory system. For those who are interested in wood and paint. For those who are allergic, furniture or kitchen utensils wrapped in PVC heat shrinkable film are very suitable. By using a PVC heat shrinkable film as a decorative film, it is possible to use a medium-density board, a particle board, a plywood, and a fiberboard in a large amount, thereby reducing the amount of wood used, thereby reducing damage to forests and the environment. From this perspective, the heat shrinkable film has made a great contribution to the protection of the ecological environment.
The choice of heat shrink film customers usually first consider the specific selection mode from the cost. Heat shrinkable packaging and laminated film can usually achieve the same packaging effect, then how to decide which packaging film to use? In general, the main differences are the requirements for the packaging pattern, the frequency of packaging required, the shelf life requirements, and the physical properties of the packaging itself such as liquid, powder, granules, solids, squares, and the like. The following guidelines help customers to select the right packaging materials: the size of the food factory; whether the service is industrial or retail; adjustment requirements; shelf life requirements; anti-abuse requirements; product shape; whether it is used for preservation, freezing or No other environmental requirements; the consistency of the packaging production company and the customer culture.
The heat shrinkable film production process is to dry the PET copolymer resin first, taking the production process of the BOPET film as an example. Then, it is added to the extruder for melt extrusion, cold drum casting through a die, and then the slab is heated to a temperature above the glass transition temperature, below a melting temperature, and under the action of an external force, one-way or Stretching in a two-fold multiple is usually required to perform a stretch of 3.5 to 4.0 times in the lateral direction. The PET macromolecular chain is oriented in the direction of the external force by stretching, and then cooled and shaped to "freeze" the oriented PET molecular structure. The high elastic deformation under the action of external force has a heat-shrinking memory effect. When the film with the "memory effect" is reheated above the stretching temperature, the macromolecular orientation structure is frozen and begins to relax. PET film shrinkage. It is worth mentioning that the PET film shrinkage is mainly contributed by the amorphous part of the orientation. This is why the copolymerized modified amorphous PET film (APET or PETG is heat shrinkable than the ordinary crystalline PET film). Therefore, the purpose of greatly increasing the heat shrinkage rate of the film can be achieved by increasing the orientation of the amorphous region in the film. As described above, the heat shrinkage rate of the ordinary polyester film is only 30% or less, and copolymerization. The modified polyester has a heat shrinkage rate of up to 70% or more.