It is well-known that retort bags gradually replace part of cans and glass jars because of their light weight, small volume, fast heat conduction and short sterilization time, which can better maintain the color and aroma of the contents. However, due to the many properties of their packaging materials, , Sterilization and other processes have a greater impact, there is also the potential risk of breaking the bag.
The reason, probably have the following two points:
One reason: the substrate problem
The cooking bag is heated together with the product, which determines the cooking bag surface material has very good stability after cooking, especially the stability of the size after cooking cooling, if the thermal stability of the substrate is not good, prone to After cooking, cooling and shrinking will cause bag breakage.
Cooking bags generally use high temperature resistant PET, NY, AL, RCPP and other substrates, should pay attention to the shelf life of various substrates, in particular, should pay attention to the shelf life of RCPP, RCPP as the inner material of high-temperature cooking, cooking The performance of the bag plays a central role. If the quality of the RCPP is poor or the shelf life has expired, there will be a significant brittle fracture when cooled under pressure after cooking and cooling.
The second reason: the impact of bagging process
Heat sealing knife temperature, pressure and speed is the bag making process of the three major elements, in order to make a good bag sealing need three reasonable match. Heat-sealing is the result of the combined effect of heat and force. On the one hand, the sealing surfaces in the molten state, the macromolecules diffuse, permeate and entangle with each other to reach airtight sealing; on the other hand, the polymer molecules in the molten state are heated by means of heat Seal the pressure of the tool so that the upper and lower layers of the film fused together as one, after cooling stereotypes to maintain a certain intensity.
Due to the high requirements of the use of the environment, generally require cooking bags have a strong heat seal strength, which requires a combination of the structure of the cooking bag and the inner material temperature and pressure settings reasonable, in making stand-up pouch, with particular attention to complement The junction with the bag at the point of closure, because in the cooking conditions, as the material shrinks, the transfer of bits will become the focus of moisture, hot air attack. The number of heat-sealing has a great influence on the strength of heat-sealing. When making bags, the horizontal sealing is set reasonably. The number of vertical sealing can well ensure that the sealing edges have good heat-seal strength.
At the same time, should pay attention to the heat seal after the cooling, cooling under a certain pressure, the lower the temperature of the heat sealing just the location of stereotypes to eliminate stress concentration process. Therefore, the bag making process, especially the cooking bag making, with particular attention to temperature, pressure, speed and reasonable distribution to ensure that the retort bag in the subsequent treatment can not break the bag.