The application of polypropylene (PP) materials in beverage bottle caps also has significant advantages, especially in high temperature tolerance, rigidity and special functional requirements. The following are its core advantages and differentiated features from polyethylene (PE):
1. Excellent high temperature resistance
High temperature sterilization adaptability: The melting point is as high as 160-170℃, and it can withstand 121℃ high temperature boiling sterilization (such as tea beverages, aseptic filling of dairy products), while PE is easy to deform above 100℃.
Hot filling stability: Suitable for 85-95℃ hot filling beverages (such as juice, herbal tea), the bottle cap still maintains sealing after cooling, and the shrinkage rate (1-2%) is lower than PE.
2. Higher mechanical strength
Compression and torsion resistance: The flexural modulus (1.5-2 GPa) is 2-3 times that of PE, suitable for wide-mouth bottle caps that need to be opened and closed multiple times (such as jam bottles, sports drinks), and the thread fatigue resistance is better.
Thin-wall design: It can maintain structural strength at a thickness of 0.2-0.3mm, reducing the material consumption by 15% compared to PE.
3. Chemical stability and safety
Oil resistance: The barrier property to oily ingredients (such as milk-containing beverages) is better than PE, and the migration amount is <0.01 mg/dm² (GB 4806.7-2016 standard).
No plasticizer: No plasticizer is required, and it has passed FDA 21 CFR 177.1520 certification, and its safety is equivalent to PE.
4. Processing and functional design advantages
High-precision injection molding: The fluidity (MFR 20-50 g/10min) is better than PE, and complex structures (such as multi-layer anti-counterfeiting tooth rings and air pressure balance valves) can be formed.
Optional transparency: The transparency of homopolymer PP can reach 90% (haze <10%), which is suitable for bottle caps that need to display content (such as high-end mineral water).
5. Environmental protection and sustainability
Recycling compatibility: It belongs to the same polyolefin as PE, but has a lower density (0.89-0.91 g/cm³) and higher flotation separation efficiency.
Low-carbon production: The energy consumption per kilogram of PP production is about 18-22 MJ, which is 5-8% lower than PE (data source: Plastics Europe LCI).
6. Special function expansion
Loose-leaf cover design: Utilizing PP's fatigue resistance, it can be opened and closed repeatedly for more than 5,000 times (such as sports water bottle cover).
Integrated sealing gasket: Through co-injection molding and TPE (thermoplastic elastomer), air tightness is improved (such as carbonated beverage cover leakage rate <0.2%).
Industry application data:
PP accounts for about 35% of beverage caps (mainly used in dairy products and tea drinks), with an annual growth rate of 6% (IMARC Group 2024).
- The use rate of PP caps in the Japanese market exceeds 50% (due to hot drink culture), while Europe tends to PE (mature environmental recycling system).
PP has become the first choice for functional beverage packaging by balancing heat resistance, strength and design flexibility, and has greater potential in smart packaging (such as integrated temperature sensing labels) in the future.
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