What are the characteristics of the composite bag process
The composite bag is made of polyester, nylon, aluminum foil, and special polyolefin film adhesives through a dry lamination process to make a composite film, which is then cured, cut, and made into a retort bag. After the food is packaged in the composite bag, it is also subjected to high-temperature sterilization at 121-135 °C for 30-40 minutes. Not only the film used for bag making must be resistant to high temperatures, but also the adhesive used to bond the film must be resistant to high temperatures, otherwise, after cooking, it is easy to cause adverse phenomena such as a decrease in bonding strength between films and delamination. At present, the adhesives mainly used for compounding retort bags on the market are mainly imported products. The Chemical Research Institute has recently developed an adhesive for retort bags that can withstand high temperatures of 135 °C. After several compound tests on the machine, its retort resistance, content resistance, and hygiene safety all meet the requirements of domestic manufacturers.
After packaging food in composite gusset bags, it must be sterilized at 121-135 ℃ for 30-40 minutes, and the packaging materials used must be high-temperature-resistant. Materials commonly used in retort pouch packaging include polyester (PET), nylon (NY), aluminum foil (Al), cast polypropylene (CPP), etc. The adhesive is a two-component polyurethane adhesive that is resistant to high-temperature cooking. The composite film is made by the dry composite process.
The main process of dry lamination is that the first base material is glued by the screen roller, then enters the drying tunnel to heat and dry, and the second base material is heated and pressurized by the lamination steel roll, and then wound up to form a composite film. Then it is sent to the drying room for heating and aging for a few days, and then it is cut and bagged.