In the fields of medical packaging, food containers and electronic protection, material properties directly determine product market competitiveness. Based on the perspective of material science, injection mold processing and injection molding technology, this paper compared and analyzed the core differences between PETG (modified copolyester) and PET (polyethylene terephthalate), analyzed how to achieve product upgrading through material innovation and process optimization, and provided practical solutions.
First, material performance comparison: how does PETG break through the traditional limitations
1. Optical performance: from basic transparency to medical grade visibility
The light transmittance of PETG was more than 90%, which exceeded 85% of PET, and met the requirements of ISO 11607 for nontoxic testing of contents.
Low temperature anti-atomization characteristics: PETG still maintains clarity in the environment of -40℃, avoiding the atomization problem caused by crystallization of PET (case: a biological reagent bottle manufacturer switched to PETG and the cold chain transportation complaint rate decreased by 67%).
2. Mechanical strength: from anti-breakage to anti-extreme environment
PETG has an impact resistance of 45kJ/m² (GB/T 1843), which is 5 times that of PET, and is suitable for fragile packaging. After PETG injection molding of an electronic product shell, the pass rate of 1.5 m drop test increased from 78% to 95%.
Low temperature resistance toughness: the bending strength retention rate of PETG is over 90% at -80℃, which is suitable for ultra-low temperature drug storage.
3. Chemical stability and compliance certification
Comparison of chemical resistance: PETG was tolerant to 75% ethanol for more than 500 hours, and PET showed stress cracking after only 200 hours (test standard: ISO 22088).
Dual certification advantages: through FDA 21 CFR and EU 10/2011 food contact material certification, support ethylene oxide/gamma ray sterilization process.
PETG
Two, process optimization: to achieve the optimal solution of performance and cost
1. Fine control of injection molding parameters
Drying process: PETG should be dehumidified and dried at 80℃ for 6 hours (dew point -40℃), humidity should be less than 0.02% (reference DIN 53715 standard) to avoid bubble defects.
Temperature segmentation strategy:
Feed area: 220-230℃ (prevent bridge building)
Melting zone: 240-260℃ (equilibrium fluidity)
Nozzle zone: 255-270 ° C (to reduce shear degradation)
2. Mold design innovation
Hot runner system: reduce melt pressure loss caused by cold runner (can reduce energy consumption by 15%)
Optimization of exhaust groove: depth 0.02mm+ width 5mm (GB/T 4169.11), to solve the problem of insufficient filling of thin-walled parts
3. Whole life cycle cost management
Item of cost
PET
PETG
Strategy of optimization
Cost of raw materials
low
20 to 30 percent higher
Process optimization reduces losses by 5-8%
Post-processing cost
Need to anneal
No need
Reduce the process and shorten the cycle by 12%
Transportation damage cost
high
90% lower
Insurance costs dropped by 50%
3. Application scenarios and value verification
1. Medical packaging upgrade program
Instead of glass ampoules, PETG injection molded penicillin bottles have achieved light weight (40% weight loss), passed the USP Class VI biocompatibility test, and saved more than 2 million yuan in transportation costs per year.
Surgical instrument tray: 0.8mm thin-wall injection molding, gamma sterilization without yeluting, certified by German TUV.
2. Innovative practice of food packaging
Oil resistant container: PETG edible oil bottle in 60℃ accelerated aging test, transmittance retention rate is 35% higher than PET.
Microwave packaging: through the FDA 21 CFR 177.1632 certification, temperature up to 110℃, a fast food brand repurchase rate increased by 40%.
3. Breakthroughs in electronic protection
High impact resistant case: The 2mm wall thickness PETG case has passed the IK10 collision class test (IEC 62262) for industrial handheld devices.
Light transmission component: light transmission rate 90%+ UV resistance modification, used for outdoor equipment display cover, weather resistance over 5 years (QUV aging test).
Fourth, industry trends and sustainable development
1. Direction of technical iteration
Bio-based PETG: 30% bio-based content is commercialized (BASF Ecovio® series), reducing carbon emissions by 18%.
Intelligent recycling system: chemical depolymerization technology can increase the PETG recovery rate to 95% (research results of Ningbo Institute of Materials, Chinese Academy of Sciences, 2023).
2. Domestic substitution process
In 2023, China's PETG production capacity reached 280,000 tons (data source: China Plastics Processing Industry Association), and the self-sufficiency rate of the key raw material CHDM exceeded 70% (China Resources Chemical Materials Technology Annual Report).
