A：We have 2 kinds of products with 7 layers normal standard as Frozen grade EVA heat shrink bags and films and Chilled fresh grade PVDC high barrier heat shrink bags and films, but with the customization requirements for 5 layers and 9 layers.
A：Key Differences As Follows:
1.Oxygen Barrier
EVOH: Best at low humidity (RH <60%, down to 0.1–0.5 cc/m²·24h·0.1MPa), but drops sharply in high humidity.
PVDC: Stable across all humidity (≤1.5 cc/m²·24h·0.1MPa), superior in high-humidity conditions.
2.Moisture Barrier
EVOH: Hygroscopic, relies on PE/PA outer layers for protection.
PVDC: Naturally low permeability; moisture barrier is 3–13x stronger than EVOH at high humidity (RH 80–100%).
3.Chemical & Odor Resistance
EVOH: Good oil resistance; odor barrier is humidity-dependent.
PVDC: Excellent oil, acid/alkali, and solvent resistance; superior, humidity-independent odor/flavor barrier (no absorption or release).
4.Humidity Sensitivity
EVOH: Very sensitive; barrier performance plummets above RH 60%.
PVDC: No sensitivity; barrier properties remain consistent regardless of humidity.
5.Typical Uses
EVOH: Low-moisture, oxygen-sensitive products (coffee, nuts, cheese).
PVDC: High-moisture, high-barrier, sterilizable applications (meats, pharmaceutical blister packs).
