Author: Site Editor Publish Time: 20-01-2026 Origin: Site
In the food packaging industry, PE (polyethylene) is hailed as the "cornerstone of packaging." But even though they are both PE, why can some bags keep food fresh for months while others are prone to leaking and breaking? Today, we will use real laboratory data to deeply analyze the performance boundaries of food-grade PE.
In practical applications, we rarely use a single PE resin, but rather achieve the optimal balance through formulation modification.
| Performance indicators | LDPE | LLDPE | HDPE |
| Transparency | High Clarity | Medium | Semi-transparent/frosted |
| Heat seal strength | Good | Excellent | Poor |
| Puncture resistance | Generally | Better | Extremely strong |
| Application scenarios | Bread bags, lightweight film | Liquid packaging, frozen food | Grain bags, heavy-duty bags |
1. Migration Test
This is the most critical indicator for food packaging. According to FDA 21 CFR 177.1520, we simulated extreme environments for 10 days (40°C, hexane extraction) on the samples.
Test Results: The total migration is far below the EU (10mg/dm²) and US FDA standards.
Professional Recommendation: We insist on using 100% virgin resin and refuse recycled materials to ensure no odor residue after heating or contact with oily foods.
2. Water Vapor Transmission Rate (WVTR)
The shelf life of food depends on its barrier to moisture.
Measured Data: Under conditions of 38°C and 90% humidity, the WVTR of a 0.05mm thick PE film is approximately 5-7 g/(m²·24h).
Performance Enhancement: If your product has extremely high moisture resistance requirements (such as powdered food), we recommend using multi-layer co-extrusion technology, which adds a barrier layer in the middle of the PE.
Many customers report that PE bags are prone to ink fading during printing. This is because PE is a typical non-polar material.
Technical Assessment: Freshly produced PE film typically has a surface energy below 30 dyne/cm², making ink adhesion difficult.
Our Process: It requires online corona treatment to raise the surface energy to 38-40 dyne/cm².
Experimental Conclusion: After treatment, the PE film achieves an ink adhesion rate of over 98% in the "3M tape peel test".
As a manufacturer with many years of experience in the industry, we offer the following technical selection advice:
Frozen Foods (below -18°C): A minimum of 20% Metallocene PE must be added to enhance drop impact resistance at low temperatures and prevent bags from becoming brittle during cold chain transportation.
Automated Packaging Lines: The coefficient of friction (COF) must be strictly controlled. It is generally recommended to maintain a COF between 0.2 and 0.3. Too high a COF can easily cause jamming, while too low a COF can cause stacking to slip.
Environmental Trends: Currently, the North American and European markets have extremely high requirements for fully recyclable materials. We recommend using a mono-PE structure to replace the previous PET/PE composite structure, facilitating entry into recycling systems.
Objective data speaks louder than words.
In the packaging industry, data doesn't lie. A complete test report (TDS/COA) is the "identity card" of every batch of goods.
Do you need a packaging solution tailored to your specific product? We can provide you with free oxygen/water vapor transmission rate simulation calculations. Simply tell us your product characteristics, and we will customize the optimal PE thickness and formulation for you.
