1、 Common structure of cooking bag
*PET/AL/CPP（PE）
*PET/NY/AL/CPP（PE）
*PET/AL/NY/CPP（PE）
*NY/AL/CPP
*NY/CPP（PE）
*PET/ CPP（PE）
*PET/NY/CPP（PE）
2、 Requirements for cooking bags
*Barrier: good air and moisture resistance, good mechanical strength.
*Hygiene: non toxic, odorless, residual solvent less than 5mg / m2; no decomposition and precipitation of harmful components after high temperature cooking.
*Content resistance: medium resistance (acid, spicy, salt, alkali), oil resistance, oil absorption rate is less than 1%.
*Heat resistance: Cooking resistance, instantaneous high temperature resistance.
*Mechanical strength: excellent pressure resistance, after high temperature cooking, it is required not to break the bag, not to change color, not to deform, not to separate layers.
*Appearance: smooth and good, no wrinkle, bubble and foreign matter adhesion.
3、 Sterilization temperature of cooking bags
*Low temperature cooking bag (sterilization at 105 ℃ for 30 minutes)
*Medium temperature cooking bag (121 ℃ 40 min sterilization)
*High temperature cooking bag (sterilization at 135 ℃ for 20-30 minutes)
*Ultra high temperature sterilization bag (145-150 ℃, several seconds to several minutes)
4、 Selection of materials and structure of cooking bags
The transparent structure should be composed of pet, NY, CPP and PE
The structure containing Al material should be selected for opaque type
The thickness of the inner material depends on the size of the bag and the amount of the contents, and the bearing strength should be ensured
The main indexes include corona strength, tearing strength, tensile strength, temperature resistance and surface cleanliness. There are few additives, and it is not easy to precipitate after cooking. The inner layer material has good anti pollution and heat sealing.
The emphasis is on the selection of Al and NY materials
Al: hot rolled stock, pinhole number, cleanliness, elongation 1%, tensile strength 65N / mm2, corona strength and thickness selection.
NY: to understand its molding methods, there are mainly step-by-step stretching, synchronous stretching and tube film forming. The film with uniform thickness and good anisotropic shape is the one with good synchronous stretching molding, and only a small part of it is used for cooking and packaging. When used in the middle layer, choose double corona if necessary. At the same time, it should be well packed because NY is easy to absorb moisture.
Selection of ink, glue and solvent
The appropriate ink and glue suitable for cooking conditions should be selected and verified in production.
The solvent mainly emphasized here is ethyl ester, and the purity should meet the requirements (water content should not exceed 0.1%, alcohol should not exceed 0.1%, free acid should not exceed 0.004%).
5、 It is suggested that the manufacturers of cooking bags should be equipped with testing instruments
*Cooking pot with adjustable temperature and pressure with back pressure
*Tensile tester
*Analytical balance for sizing
*Gas chromatograph
*Moisture meter
*Withstand voltage tester
*Corona pen or self-made treatment solution
6、 Production of cooking bags
As far as possible, less printing patterns should be selected for larger cooking bags, and blank edges should be left around the hot sealing edge
Understand the production conditions of food enterprises using cooking bags, and tell them that the temperature should be strictly controlled within the range guaranteed by the manufacturers of cooking bags. Even if the temperature exceeds a few degrees, because all kinds of materials often reach the limit that they can bear, it is very important to ensure the performance of cooking bags.

Food enterprises should do a good job in confirming the performance of cooking bags before batch use, that is to say, the validation of process conditions for the use of cooking bags under specific process conditions. Because of the physical and chemical properties of the inner packaging materials and the new substances produced by the possible physical and chemical changes under high temperature, the cooking bag layer may penetrate, resulting in the decline of the packaging performance of the cooking bag, such as delamination. Even if the vacuum degree in the cooking bag may cause the stress difference among the layers of the cooking bag, and cause the delamination between the film layers with poor fastness.

The production enterprises of cooking bags should strengthen the management, do a good job in the detection and control of the process indexes of each process, especially the last pass of the cooking test before leaving the factory.
*Before feeding, it is necessary to check whether the corona treatment of the film meets the requirements, which is very important for the printing fastness and composite fastness.
*Ensure the aging time, so that the two-component ink or glue fully cross-linked curing reaction.
*Pay attention to the state of two-component ink or glue in use. The amount of used ink or glue must be controlled within a certain range. The same batch of raw and auxiliary materials should be selected for one order as far as possible, so as to facilitate inspection and tracking.
*Use in strict accordance with the product instructions provided by the material manufacturer, especially the curing dose of ink and glue must be used according to the requirements, and the glue amount should be uniform.
*It is necessary to simulate the process conditions used by food enterprises to test the performance of finished bags, and urge food enterprises to confirm the performance of cooking bags, so as to prevent more losses.
5) Cooking bag manufacturers should do a good job in the compatibility of various packaging and printing materials
Due to the limitations and particularity of the use range of various products, it is impossible to control or take into account all aspects of post-processing and further processing and use of various users. The processing and processing of downstream products and the use requirements of subsequent products are not necessarily fully understood.
*The test should run through the whole production process, not just in the printing stage.
*Pay attention to the high temperature resistance, especially pay attention to the adhesion drop or delamination caused by the leakage of various additives in the film at high temperature.
*When replacing materials from different manufacturers, or even using materials from the same manufacturer but with different batch numbers, compatibility test should also be carried out.
6) When making products with al structure, the compound equipment and post process equipment (slitting machine and bag making machine) should be cleaned before production.
Due to the large amount of glue used in cooking and packaging, the air volume and temperature of the composite equipment should be adjusted, and the machine speed should be controlled to ensure that the solvent is fully volatilized and avoid the drop of strength due to false drying. Pay attention to environmental humidity when making products with NY structure.
7) When making bags, while ensuring the heat sealing strength, we should pay attention not to damage the heat sealing material and cause the excessive extension of Al material.