Views: 201 Author: Site Editor Publish Time: 2021-07-09 Origin: Site
At present, the milk powder packaging bags sold in the market mainly include metal cans and printed plastic packaging bags. Metal cans have good sealing performance and long shelf life, but their production and transportation costs are relatively high, so only a few large-scale well-known dairy enterprises apply this packaging form to some products. Canned milk powder of the same quality is generally more than 30% more expensive than bagged milk powder in terms of market price. Therefore, with the intensification of competition in dairy industry, due to the influence of cost factors, metal can packaging is likely to be gradually replaced by lightweight plastic standing pouch.
Nowadays, packaging bags with aluminized structure are safer than BOPP structure. Among them, the packaging cost of standing pouch alufoil structure is relatively high, but the shelf life is longer, generally reaching one and a half to two years. As for BOPP structure, because of its poor heat resistance, BOPP material is generally not suitable for automatic packaging machine, which is mainly used to make prefabricated bags for manual packaging. In daily production, we use heat sealing aluminum foil composite materials to produce milk powder packaging bags.
Aluminum foil has good moisture-proof, rust-proof, gas-blocking, light-shielding and corrosion resistance, moderate stiffness and mechanical strength, good ductility and easy processing. It can be compounded with paper and plastic to make high-barrier and high-temperature resistant aluminum-plastic composite material, which is suitable for high-temperature sterilization printed aluminium bags and vacuum packaging. The use of aluminum foil composite material can effectively improve the shelf life of products and resist the infiltration and dyeing of grease into seal type aluminium foil bag.
Aluminum foil packaging also has its own limitations, for example, aluminum foil is not folding resistant, and it is prone to pinhole, perforation, fracture and other problems in the process of vacuum packaging or product circulation. After rubbing, the barrier performance of aluminium zipper pouch will greatly decrease, and even there will be penetrating perforation. However, if high barrier layers such as PA and EVOH are added to the composite layer, it can not only protect the aluminum foil, but also keep the barrier property of the material with aluminum foil perforation at a high level. Therefore, when milk powder aluminium foil standing pouches are squeezed and kneaded during distance transportation or storage, the properties of aluminum foil composite materials will be affected if such packaging is selected. The commonly used composite materials are PET / AL / CPP, PET / AL / PA / CPP, PET / NY / AL / NY / CPP and so on.
However, in general, the more the number of composite layers, the better the barrier properties and physical properties, but the higher the cost. It is wasteful and unnecessary to excessively improve the aluminium pouch packaging properties. In the design of packaging materials, the packaging materials should be selected reasonably in combination with the milk powder aluminum foil ziplock bags and shelf life.