Aluminum foil packaging bags are used in electronic packaging bags and retort packaging bags. How to make an aluminum foil bag that satisfies customers and quality? The following is a small series to bring you from the material side to solve problems for everyone. [aluminum foil packaging bag]
At present, the cooking temperature of the market is above 121 ° C (inclusive), and the high temperature cooking package containing aluminum foil mainly has the following two material structures, namely BOPET/AL/RCPP and BOPET/AL/BOPA/RCPP. The following authors focus on the analysis of these two structures, and discuss with you, I hope to do a good job, and help you to do this kind of packaging.
BOPET is mainly made of polyester (PET) chips. It is a high-grade plastic film with excellent performance after biaxial stretching. It has high transparency, non-toxic and tasteless, high tensile strength and good stiffness. It has excellent properties such as tear resistance, non-breakage, excellent electrical and optical properties, good oxygen barrier properties, cold resistance (-70 ° C), heat resistance (200 ° C), and chemical resistance and shrinkage stability. BOPET should be selected to note that the heat shrinkage rate is ≤2% in the longitudinal direction at 150 °C and 30 min, the lateral direction is ≤1.5%, and the surface tension is not less than 45 mN/m.
Aluminum foil is the only metal foil in flexible packaging materials and has a long application time in the packaging field. Aluminum foil is a metal material, and its water-blocking, gas-blocking, light-shielding, and taste-keeping properties are difficult to achieve with any other packaging materials, and are packaging materials that have not been completely replaced so far. Aluminum foil is made of electrolytic aluminum with a purity of 99.0%~99.97%. After repeated calendering, it has abundant resources and considerable performance and price ratio. The aluminum foil for retort packaging should be 9-micron thick grade A soft aluminum foil.
The BOPA film has high puncture strength, impact strength, friction strength, flexural strength and good barrier properties. When using BOPA, we should pay attention to the characteristics that it is highly susceptible to moisture and water deformation. As the material of the intermediate layer, double-sided corona treatment is required, and the surface tension is not less than 50 mN/m, and some customers use a single-sided BOPA for compounding. The strength after compounding will be much lower, and increasing the amount of sizing of the non-treated surface will make up for it.
The characteristics of RCPP film are transparency, goodness, good flatness, good temperature resistance, certain stiffness, no loss of flexibility and good heat sealing. RCPP containing aluminum foil packaging should pay attention to the heat shrinkage rate not too large. When selecting, it should take into account the difference in content and materials, and have certain pertinence, especially when doing some substances containing oils and acids and acids and bases. It is recommended that the CPP thickness of the cooking be not less than 80 μm, and suppliers with better physical control should be selected, and the corresponding products should be selected for the special requirements of the contents.
Special attention should be paid to the use of inks for retort packaging. It is necessary to select a two-liquid polyurethane ink with good temperature resistance. The two-liquid polyurethane ink must be added with a curing agent. Otherwise, some free curing agents in the ink will consume part of the curing agent. There is not enough curing agent to react with the main agent, so that the adhesive layer cannot be completely cured. Lighter after cooking, the peel strength is low, and the adhesive layer is back-adhesive; in severe cases, the ink layer and the aluminum foil are layered, which affects the appearance of the package and the barrier property.