Which is the preferred packaging material for milk powders? Many milk powder manufacturers choose aluminized packaging materials, why?
Aluminum-plated structure packaging film is safer than BOPP structure. Among them, the cost of packaging with aluminum foil structure is relatively high, but the shelf life is longer, generally up to one and a half to two years. The packaging cost of aluminized structure is relatively low, but the shelf life is relatively short, generally not more than one and a half years. As for the BOPP structure, due to the poor heat resistance of the BOPP material itself, it is generally not suitable for use on an automatic milk powder packaging machine. It is mainly used to make prefabricated bags for manual packaging.
Aluminum foil has good moisture-proof, rust-proof, gas-barrier, light-shielding and corrosion resistance, moderate stiffness, mechanical strength, good ductility, easy to process, and can be combined with paper and plastic to make a high-barrier, high-temperature resistant aluminum-plastic composite material , Suitable for high temperature sterilization packaging, vacuum packaging, etc. The use of aluminum foil composite material can effectively improve the shelf life of the product and resist the penetration of grease into the packaging.
Aluminum-plastic packaging also has its own limitations. For example, aluminum foil is not resistant to folding, and aluminum foil is prone to pinholes, perforations, and breakage during vacuum packaging or product circulation. The barrier performance of aluminum-plastic packaging is greatly reduced after kneading, and even penetrating perforations appear. However, if a high-barrier layer such as PA and EVOH is added to the composite layer, it can not only protect the aluminum foil, but also maintain the barrier properties of the material that has perforated aluminum foil at a higher level. Therefore, when the packaging material of milk powder is easy to squeeze and knead during transportation or storage and transportation, if this type of packaging is selected, the performance of the material compounded with aluminum foil is very important. Commonly used composite material designs include PET/AL/CPP, PET/AL/PA/CPP, PET/NY/AL/NY/CPP, etc.
In general, the oxygen transmission rate of the aluminum-plastic composite film is less than 12.5px3/.24h.0.1MPa, and the water vapor transmission rate is less than 0.5g/.24h. It is a commonly used packaging material for milk powder. Relatively speaking, the more composite layers, the better the barrier performance and physical properties, but the higher the cost, and it is wasteful and unnecessary to increase the packaging performance excessively. In the design of packaging materials, a reasonable selection should be made in consideration of the milk powder packaging technology and shelf life requirements.