Flexible packaging is widely used in food, medicine, daily chemical and other fields because of its advantages such as portability, low cost and strong plasticity. The choice of materials directly affects the shelf life, safety and environmental protection of products. Common soft packaging materials mainly include plastic, aluminum foil, paper and composite materials.
1. Plastic film
Plastic is the core material of flexible packaging, and the common types include:
Polyethylene (PE): It can be divided into high density (HDPE) and low density (LDPE). The former has high hardness and the latter has good flexibility, and is often used in plastic bags and plastic wrap.
Polypropylene (PP): High temperature resistance, high transparency, commonly used in fast food packaging, candy bags.
Polyester (PET): It has high strength and puncture resistance, and is often used for packaging beverage bottles and snacks.
Polyamide (PA, nylon): Good oxygen barrier, used for vacuum packaging of meat.
2. Aluminum foil
Aluminum foil has excellent barrier properties (light-proof, oxygen-proof and moisture-proof), and is often used in high-end food (such as chocolate and coffee) and medicine packaging. However, it has strong plasticity and is usually used in combination with plastic or paper.
3. Paper and paper-based materials
Environmental protection paper packaging (such as kraft paper and coated paper) is mostly used for dry food or environmental protection packaging. Moisture resistance can be enhanced by coating (such as PE coating), such as paper cups and fast food boxes.
4. Composite materials
The defects of a single material can be made up by the composite of multilayer materials, and the common structures include:
BOPP/PE: It has both strength and tightness, and is used for potato chip bags.
PET/ aluminum foil /PE: high barrier property, used for milk powder and medicine.
Paper/aluminum foil /PLA: degradable and environmentally friendly material for sustainable packaging.
5. Environmental trends
With the tightening of environmental regulations, bio-based materials (such as PLA and PHA) and recyclable design (single material structure) have become the focus of research and development. For example, the application of water-based ink and solvent-free adhesive is also reducing pollution.
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The choice of flexible packaging materials needs to balance function, cost and environmental protection requirements. In the future, the combination of high performance and sustainability will be the core direction of industry development.
