Analysis on the production and application of high temperature resistant cooking bag

With the rapid development of China's economy, the improvement of people's life rhythm and the rise of tourism, the requirements for the quality of staple foods are getting higher and higher. The production of soft cans has been successful in the United States since 1959, and its output has increased year by year. It is also moving toward a multi-magnetized track. In order to ensure its shelf life, the requirements for the outer packaging of the product are extremely strict. The high-temperature retort pouch has the characteristics of long-lasting packaging, stable storage, anti-bacterial, high-temperature sterilization, etc. It is the best packaging compound for soft cans. material.
First, the structure and material selection of high temperature resistant cooking bags
In order to meet the performance requirements of the retort pouch, the outer layer of the structure is selected to have a high-strength polyester film, the middle layer is selected to have a light-shielding and air-tight aluminum foil, and the inner layer is a polypropylene film. The three-layer structure includes PET/AL/CPP/, PPET/PA/CPP, and four-layer structure with PFT/AL/PA/CPP.
1, polyester film
Polyester film has the characteristics of large mechanical strength, heat resistance, cold resistance, chemical resistance, gas barrier, etc. Its thickness is 12gm, but many domestic polyester films have poor temperature resistance and the flatness of the product is not stable. It brings great difficulties to the operation and causes waste.
2, aluminum foil
Aluminum foil is excellent in gas barrier properties and moisture resistance, and is therefore important for preserving the original taste of food. The protection is very strong, so that the package is not easily attacked by bacteria and mold; the shape is stable at high temperature and low temperature; the light shielding property is good, and the reflection ability to heat and light is strong. Its thickness can be used at 7, the pinhole is as small as possible, the aperture may be small, in addition, its flatness must be very good, the surface is free of oil spots, the value of domestic aluminum foil generally can not meet the requirements, many manufacturers choose South Korea and Japan product.
3, nylon
Nylon is not only good in separation, but also odorless, tasteless, non-toxic, and particularly resistant to puncture. It has a weakness that it is not resistant to moisture, so it should be stored in a dry environment. Once it absorbs water, its performance indicators will decrease. The thickness of Niyou is 15gm. It can be used. When compounding, it is best to use a double-sided film. If it is not a double-sided film, the untreated surface should be combined with the aluminum foil to ensure the composite fastness.
4, polypropylene
The polypropylene film in the inner layer of the high-temperature cooking bag not only requires good flatness, but also has strict requirements on tensile strength, heat-sealing strength, impact strength and elongation at break. Only a few products in China can be used. However, the effect is not comparable to the imported raw materials, the thickness is 60-70gm, and the surface treatment value is above 40dyn.
5, the adhesive
The viscous bag of the retort bag requires strong adhesion fastness, and it can withstand the high temperature of 121-135 ° C, and the glue amount is 4-5 g/m 2 dry weight. Many domestic composite plants use AD502, 503H. .
Second, the production process
1. Machine maintenance before production
Before starting production, the machine must be thoroughly maintained. All rollers must be clean and free of adhesives and other debris. The composite rubber roller and the upper adhesive roller are preferably replaced with new spare parts. Both are adjusted in parallel.
2, process parameters
When producing, if the quality of the aluminum foil is good, it is necessary to pass the guide roller as little as possible. The other substrates are kept flat by the tension and the hand fine adjustment device before entering the composite roller. The humidity of the environment is maintained above 85%, the composite drying humidity is 50 degrees, 70 degrees 85 degrees, the composite temperature is 85-90 degrees, the composite pressure is 0.4-0.5mpa, and the machine speed is generally 60-90m under the condition of ensuring drying. /min.
3, ripening
After each compounding, it should be kept in the curing room of 40 degrees or more for 48 hours, and then the next time the compounding is completed. Finally, the finished product should be cooked for 4 weeks to make the bag, but the curing time is too long, and the bonding fastness will be decline.
Third, the bag
Bag making process and heat sealing temperature heat sealing pressure and machine speed are related to the heat sealing temperature determined by the thickness of the composite film and the inner layer material. Generally, it is controlled between 170-230 degrees. The pressure should be adjusted properly and the pressure is too low. If the pressure is too high, the inner layer of Resin will be squeezed out, so that the thickness of the seal is reduced, which affects the strength of the bag. At the high temperature sterilization, it is easy to have stress concentration at the heat seal, and the bag is broken, and the machine speed cannot be too fast. Otherwise, the strength of the bag will also decrease.
Fourth, the performance index of high temperature cooking bags
The bags are produced, the first batch must be sampled and the performance must be in accordance with the indicators.
Five, high temperature sterilization process
Although each batch of processed products is qualified at the factory inspection, if the application process is unreasonable, it will also cause bag breakage and affect the reputation of the manufacturer. Therefore, manufacturers should also master the sterilization process in order to find out the reasons for breaking the bag. At present, domestic high-temperature sterilization process adopts 121 degrees and 30-45 minutes. If it is found that the air pressure rises and falls, it is adjusted with water injection or steam, but the pressure must be stable and must not fluctuate. Then inject cold air, while releasing water vapor, the pressure should be stable, stop after 5 minutes, and finally put into cold water to cool, complete the sterilization process, during which the pressure fluctuation is large, the bag is severely broken.

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