Due to its light weight, small size, fast thermal conductivity, short sterilization time, and good color and flavor of the content, high-temperature cooking vacuum bags gradually replace some iron cans and glass cans. However, due to its many properties of packaging materials, bag making, Sterilization and other processes have a greater impact, so there is a potential risk of bag breaking. This paper analyzes and solves the problem of broken bags in cooking vacuum bags for reference.
Reason one: substrate problem
The cooking bag is heated together with the product, which determines that the surface material of the cooking bag has very good stability after cooking, especially the dimensional stability after cooking and cooling. If the thermal stability of the substrate is not good, it is easy to appear After cooling and shrinking, the delamination caused the bag to break.
Responses:
The cooking vacuum bags generally use PET, NY, AL, RCPP and other substrates with good high temperature resistance. Pay attention to the shelf life of various substrates, especially the shelf life of RCPP, because RCPP is an inner layer material for high temperature cooking. The performance of the cooking bag plays a central role. If the RCPP quality is relatively poor or the shelf life has passed, there will be a large degree of brittleness and cracking when the compressive pressure after cooking is cooled.
Reason two: the impact of bag making process
The temperature, pressure and machine speed of the heat sealing knife are the three major elements of the bag making process. To make a bag with good sealing performance requires a reasonable match between the three. Heat sealing is the result of the combined action of heat and force. On the one hand, on the sealing surface in the molten state, macromolecules diffuse, penetrate, and intertwined to achieve sealing. On the other hand, the polymer molecules in the molten state rely on heat The pressure of the sealing tool makes the upper and lower films fuse with each other into one, and can maintain a certain strength after cooling and setting.
Responses:
Due to the high requirements of the use environment, it is generally required that the cooking bag has a strong heat sealing strength, which requires a reasonable setting of temperature and pressure in combination with the structure of the cooking bag and the inner layer material. The point seal at the junction with the bag body, because under the cooking conditions, as the material shrinks, the junction will become the focus of moisture and hot gas attack. The number of heat seals affects the heat seal strength to a great extent, and the number of horizontal seals and vertical seals can be properly set during bag making to ensure that each edge has a good heat seal strength.
At the same time, attention should be paid to the cooling after heat sealing. At a certain pressure during cooling, the location where the heat seal has just been melted is shaped with a lower temperature to eliminate the stress concentration process. Therefore, for the process of making bags, especially the production of cooking bags, special attention should be paid to the reasonable distribution of temperature, pressure, and machine speed to ensure that the cooking bags can not be broken during subsequent processing.