From the late 1980s, China's flexible packaging began to start. Until now, the flexible packaging industry has been flourishing everywhere in the motherland, especially in the Yangtze River Delta, the Pearl River Delta and Bohai Rim. High-temperature cooking packaging bags have gradually started with the development of the flexible packaging industry, and a considerable production scale has been formed so far. Packaged soybean products, packaged chicken, duck, and fish can be seen everywhere in large, medium, and small supermarkets throughout China. Transparent or aluminum foil opaque high-temperature cooking packaging. Although there are many manufacturers of high-temperature cooking packaging, such quality problems often occur in the production process. The following discussion on the production process of high-temperature cooking packaging and precautions a little superficial view for reference. First, the structure of high-temperature cooking bag and its physical and mechanical properties Second, according to the provisions of GB/T1004-1998, the product structure is divided into three categories In fact, some manufacturers in the production process, some indicators are much higher than the national standard (such as peeling force) The choice of raw material for high-temperature cooking bag: To produce a qualified high-temperature cooking bag, we must first select qualified raw materials. 1. BOPET film, also called biaxially stretched polyester, has high rigidity, strong mechanical strength, good moisture resistance and gas barrier, and it is a good surface material for cooking bags. The thickness is generally 12 μm. The surface was corona treated with a surface tension of 52 dyne or more. 2.BOPA film: also known as biaxially stretched nylon film. Nylon has copolymerized nylon and homopolymerized nylon, and copolymerization has better softness than homopolymerized nylon. The film has large mechanical strength, good gas barrier property, oil resistance, good puncture resistance, and strong hydrophilicity. The commonly used nylon film thickness is 15μm. After the corona treated surface, the wetting tension is above 52 dyne, which is commonly used in the surface layer and intermediate layer of the composite film. When used as an intermediate layer, it is best to use two surfaces for treatment. After opening the packaging, the nylon membrane should be used up once. Using a damp BOPA membrane will affect the final product quality. 3. CPP film: Also called cast polypropylene film. Polypropylene also has copolymerization and homopolymerization, and CPP film for high temperature cooking bags should be produced with copolypropylene (homogeneous polypropylene has poor heat sealability). At present, many manufacturers use co-extrusion equipment to produce CPP films. It is also possible to use homopolypropylene in the middle layer as the core layer, but the core layer must not be too thick, otherwise it will affect the physical properties of the CUP film. When the CUP film is used in the 135°C cooking bag as the heat seal layer, the material of the CUP film is preferably a block copolymer polypropylene, and the thickness is generally 60 μm to 80 μm. The surface was corona treated with a surface tension of 40 dynes or more. 4. Aluminum foil: It is made of AOO aluminum ingots after several times of rolling. Its thickness is generally 6.5μm-9.0μm. The surface is clean and free of oil. Aluminum foil serves as an intermediate layer that acts as a barrier and a light protector. 5. Ink: The ink used in cooking bags is printed with high temperature resistant ink. Mostly polyurethane two-component inks. 6. Adhesives: Polyurethane two-component high-temperature cooking gels are generally used. According to the different requirements of high-temperature cooking, different temperature-resistant cooking gels (121°C, 125°C, 135°C, etc.) can be selected. The solid content is 50%, 60%, 66% and so on. It is best to choose a high solid content glue, on the one hand it can be used at high working concentration, which is beneficial to reduce the production cost; on the other hand, the coating quantity has a reliable guarantee. 7. Solvent: The solvent used for dry compounding is ethyl acetate, the moisture content should be less than 300ppm, and it must not contain alcohols, amines, etc. In terms of composite substrates, new substrates coated with silicon oxide or aluminum oxide have also been selected in order to increase barrier properties. However, it is rarely used in China. Third, the production process printing - the first unwinding - gluing - drying - (second unwinding) heating lamination - rolling - maturation - cut bags. Fourth, pay attention to matters 1. Check the surface tension of various composite substrates to ensure that the surface tension of each substrate meets the process requirements. 2. In the production of transparent cooking bags, the first unwinding can use BOPET, BOPA as the coating surface, the amount of glue can be controlled at 3.5g/m2 or more, and CPP as the second unwinding. If you want to do three-layer structure of BOPET/BOPA/UP, you can combine the three layers and then enter the curing chamber. In the production of aluminum foil-containing cooking bags, the aluminum box is generally placed in the second unwinding position. When the third or fourth layer is compounded, the aluminum foil layer is preferably placed in the second unwinding position. Because this layer containing aluminum foil is placed on the first unwind, the route to go is long, and more guide rollers are used, which easily causes the aluminum foil to wrinkle. In addition to aluminum foil cooking bag, the amount of glue should be 4.0g/m2 or more. 3. In order to ensure the amount of glue, the coated anilox roller should be cleaned frequently (preferably with a special anilox roller cleaner) to prevent jamming of the mesh. 4. When you choose to use plastic, it is best to choose a binder with a high solid content, so you can generally use at a higher solid content (working concentration of 28% -30%) to ensure the amount of glue. Jiangsu Jintan Adhesives Co., Ltd. can produce high-temperature cooking plastics with 60% solid content and 66% solid content. 5. It is important to choose the coating roller. Now many manufacturers plate, the version of the roller micro-hole shape pyramidal, hexagonal, inverted pyramid, etc., some holes and holes between the open channel, and some are not. I believe that the best choice for laser engraved coating roll, 80 lines -110 lines, depth 70μm-85μm, users can choose according to their own operating experience, network cable and depth, in the selection must be taken into account the amount of glue. 6. Since the sizing amount when producing retort pouches is much larger than that of ordinary pouches, the compounding process is also different. If your compound machine has good drying and ventilation performance in the drying tunnel, the speed can reach 120m/min-150m/min in the compound ordinary products, and the best speed is 70m/min-110m/ in the compound cooking bag. Min; If the performance of heating and ventilation of the drying tunnel of the compound machine is not ideal, the speed should be slower, so as to facilitate the maximum volatilization of the solvent, reduce the residual solvent and ensure the product quality. 7. Because the raw materials for cooking bags have good temperature resistance, the temperature of the laminating roller can be controlled at 60°C-70°C, which is beneficial to the initial adhesion and final strength of the composite film. 8. During production, the rubber in the rubber tank is preferably pumped and cycled, and the 3th Chann Cup is often used to measure the dryness, so as to ensure that the glue concentration is basically the same, and finally ensure the stability of the product quality. 9. The temperature of the curing chamber of the cooking bag is preferably controlled at about 55°C. The hot air circulation is used for 72 hours to achieve full cure. 10. When producing a retort pouch with printing, it is necessary to choose a cooking resistant ink, preferably two-component, and the solvent in the ink is preferably not an alcohol solvent so as not to affect the curing of the glue. 11. The bag making process of cooking bags is also very important. After the production of composite membranes, the quality of the bags directly affects downstream users. Therefore, the factory should adjust the temperature, pressure, and speed of the bag according to the performance of its own equipment (better knife edge chamfering). The above are some of my views. Although each company's raw materials, equipment performance, and production process are not the same, the ultimate goal is to produce products that meet customer requirements. In order to ensure product quality, in addition to selecting the right raw materials and suitable production process, after the product comes out, the physical and mechanical properties of the product are thoroughly tested and can only be delivered after passing the inspection. Source: China Packaging News