At present, the milk powder packages sold on the market mainly come in two forms: metal cans and aluminum-plastic flexible packaging bags. Metal cans have good airtightness and a long shelf life, but their production and transportation costs are relatively high. The market price of canned milk powder of the same quality is generally more than 30% more expensive than bagged milk powder. Therefore, with the intensification of competition in the dairy industry, the packaging of metal cans is gradually replaced by lightweight aluminum-plastic composite flexible packaging bags due to cost factors.
The basic requirements of milk powder packaging:
Excellent sealing, barrier properties, sanitation, no solvent residue, no peculiar smell, sterile, etc.
Here we list two commonly used types of milk powder packaging material:
1. Aluminum plastic structure(PET/AL/PE)
In this structure, PET belongs to the stress layer, with high tensile strength, and its excellent transparency can fully show the exquisite printing. Aluminum foil is a barrier layer for light, oxygen and water, which plays a key role in maintaining the quality and fragrance of milk powder. The inner film is a heat-sealing layer and a material that is in direct contact with milk powder. 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 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 milk powder needs to be transported over a long distance or the packaging material is easy to squeeze and knead during storage and transportation, if this type of packaging is selected, the performance of the material compounded with aluminum foil is very important. The commonly used milk powder packaging bag composite material is designed with PET /AL/CPP, PET/AL/PA/CPP, PET/NY/AL/NY/CPP, etc.
2. Plastic-plastic composite film
Plastic packaging is light in weight, thin in thickness, simple in packaging technology, rich in design types, and has good moisture and corrosion resistance. It has been widely used in food, medicine and other industries. The whole milk powder can be packaged in a composite plastic soft package, but the material must have good barrier properties. The packaging material design can choose PVDC, PA, EVOH and other materials with high barrier properties as the barrier layer, and materials such as PP and PE with good heat-seal properties as the inner layer of the packaging. Optional packaging material structure such as PA/CPP, PA/LDPE, etc.
Both types of milk powder packaging materials are suitable for our milk powder packaging machines.