Composite Process Performance of Adhesive for Cooking Resistant Compound Bags (I)

Cooking bags, also known as soft cans, were first developed by the US Army's Natick Institute to replace edible tin cans and glass cans. Due to its light weight, small size, convenient consumption, and room temperature storage, it is gradually trusted because it is comparable to traditional tinplate cans. In 1969, it was successfully applied to Apollo Aerospace Engineering. In the same year, Japan's Toyo can also put it on the market.

A composite film is made from a dry composite process using adhesives for films such as polyester, nylon, Aluminum Foil, and specialty polyolefins, and then cured, cut, and made into cooking bags. After the food is packaged, it must be sterilized by high temperature 121 ~ 135 °C, 30 ~ 40min. Not only the film used for bag making should be resistant to high temperature, but also the adhesive used for bonding the film should be resistant to high temperature, otherwise the adhesive strength between film and delamination phenomenon will easily occur after cooking. At present, the adhesives used for cooking bag complexes are mainly imported products. Liming Chemical Research Institute recently developed an adhesive for retort pouches that is resistant to high temperatures of 135°C. After several tests on the machine, the retort resistance, content resistance, and hygienic safety meet the requirements of domestic manufacturers. This article briefly describes the effect of the composite process on the bond strength and retort resistance of cooking paste.

1 Composite process and cooking resistance test

1.1 Composite Process

After cooking foods in bags, they must be sterilized at 121-135°C for 30-40 minutes. The packaging materials used must be resistant to high temperatures. Commonly used in cooking bag packaging materials are polyester (PET), nylon (NY), aluminum foil (Al), cast polypropylene (CPP) and so on. Adhesives use high-temperature cooking two-component polyurethane adhesives. Composite membranes are made by a dry composite process. Its craft mainly includes:

The first substrate is mainly a material having a small elongation and high heat resistance, and includes polyester (PET), nylon (NY), and composite film PET/Al. The second substrate is mainly a material with high elongation, easy deformation due to heat, and low tensile strength, including cast polypropylene (CPP), aluminum foil (Al) and composite film NY/CPP. The main process of dry compounding is that the first substrate is coated with a wire roller and then heated into a drying tunnel to heat and dry, and the second substrate is heated and pressed by a composite steel roll to form a composite film. Then the drying room was heated and matured for several days and cut into bags. The pilot test products for cooking plastics developed in our institute were conducted on the aircraft composite test in Zhejiang Yuhuan, Haining, Pingyao, Shanxi, and the manual compound test in this hospital. The composite process conditions are shown in Table 1.

1.2 retort test

The compounded bags were each filled with distilled water; saturated brine at 40° C.; chili sauce, tomato sauce, 3% acetic acid mass ratio of 1:1:1; salad oil, tomato paste, 3% acetic acid mass ratio of 1:1:1. ;beef. Vacuum sealing, cooking in a sterilizing pot at 135°C for 30 minutes, cutting the bag into 150mm×15mm splines, and performing T-peel strength test results on an Instron 1185 type universal material testing machine are shown in Table 2.