The retort pouch is a functional packaging bag commonly used in the food industry. It has the advantages of light weight, small volume, fast heat conduction, short sterilization time, good color and aroma of the content, and is a substitute for some tin cans and glass. A good choice for cans. However, since many functions of the packaging materials are greatly affected by the processes of bag making and sterilization, there is a potential risk of breaking the bag.
The retort pouch is heated together with the product, which requires that the constituent substrate of the retort pouch still has very good stability after cooking, especially the stability of the scale after retort cooling, if the thermal stability of the substrate is not good. For a long time, it is easy to appear that the cooking cooling is shortened and the separation layer causes the bag to break.
Manufacturers of retort pouches usually use high temperature resistant PET, NY, AL, RCPP and other substrates, should pay attention to the shelf life of various substrates, especially pay attention to the shelf life of RCPP, because RCPP as the inner layer of high temperature cooking, The function of the retort pouch plays a decisive effect. If the quality of the RCPP is relatively poor, it may have passed the shelf life. When the steam is cooled, the pressure will be largely brittle and cause cracking.
The impact of bag making technology on the quality of the bag is also particularly important. In general, the temperature, pressure and machine speed of the heat-sealing knife are the three major elements of the bag-making technology. In order to produce a bag with good sealing, the three parties need to make a perfect match. Heat sealing is the effect of heat and force. On the one hand, the sealing surface in the molten state, the macromolecules diffuse, soak, and surround each other to reach the sealing and sealing; on the other hand, the polymer molecules in the molten state are sealed by means of heat sealing. The pressure of the cutter makes the upper and lower layers of the film merge into one another, and can have a certain strength after cooling and setting.
The high requirements of the use environment require that the retort pouch has a strong heat seal strength, which requires the manufacturer to properly set the temperature and pressure on the structure of the retort pouch and the substrate of the inner layer. At the same time, the user should pay attention to the cooling after heat sealing, and at a certain pressure during cooling, the orientation of the just-melting heat-sealing is shaped with a lower temperature to eliminate the stress concentration process. Regarding the process of bag making, especially the manufacture of retort pouches, special attention should be paid to the reasonable distribution of temperature, pressure and machine speed to ensure that the retort pouch does not break the bag during subsequent processing.
