1. Materials and Structures
Single-layer plastic bottles: Made of a single material (such as polyolefin, polyester, etc.), with uniform bottle walls and simple structures.
Multi-layer composite plastic bottles: Made of 2 or more layers of different materials (such as polyethylene + barrier layer resin), a layered structure is formed through a co-extrusion process, usually including a barrier layer, a structural layer, etc. For example, the outer layer is a low-cost material (such as polyethylene), and the inner layer is a barrier resin (such as ethylene-vinyl alcohol).
2. Performance Characteristics
Barrier properties: Multi-layer bottles effectively isolate oxygen, water vapor, etc. through barrier layers, and are suitable for products with high requirements for freshness and anti-oxidation (such as food and medicine); single-layer bottles have weak barrier properties.
Strength and durability: The multi-layer structure enhances pressure resistance and temperature resistance (such as hot and cold water) through layered design. Single-layer bottles rely on the material's own properties, and have limited pressure resistance and temperature resistance.
Hygiene: Multilayer bottles can be designed with antibacterial inner layers or light-shielding layers to reduce bacterial growth and water pollution; single-layer bottles rely on the safety of the material itself.
3. Application scenarios
Single-layer bottles: Suitable for scenarios with low barrier requirements, such as ordinary daily necessities packaging and short-term storage of liquid containers.
Multi-layer composite bottles: Mostly used for products such as food, medicine, and cosmetics that require long-term preservation, light protection, or leakage prevention, such as soy sauce bottles, medicine packaging, and high-end beverage bottles.
4. Cost and process
Cost: Multilayer bottles are more expensive due to the diversity of materials and complex processes (such as co-extrusion technology); single-layer bottles have low production costs and are suitable for popular needs.
Environmental protection: Single-layer bottles are easy to recycle because of a single material; multi-layer composite bottles are difficult to recycle because of the bonding of multiple materials, and some require special treatment.
5. Other differences
Weight and portability: Single-layer bottles are lighter; multi-layer bottles may be heavier due to their complex structure.
Transparency: The transparency of a single-layer bottle is easy to control; if a multi-layer bottle contains a light-shielding layer, the light transmittance may be reduced.
In summary, multi-layer composite plastic bottles have obvious advantages in functionality and durability, but their cost and environmental friendliness are weaker than single-layer bottles; single-layer bottles are more economical and lightweight, and are suitable for basic demand scenarios.
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