Core logic: conditions first, materials second
For molded-fiber tray lamination, selection is not decided by the names "PET, APET or CPET" but by: what temperature your tray must withstand, for how long, and through which processing and use conditions?
DNW's selection path is fixed as: application conditions → film structure → lamination process → sealing/service conditions → finished-pack validation → recommended solution.
For ambient, chilled, fresh-display and clear-appearance applications, evaluate transparent APET/PET structures first; where dimensional stability at elevated temperature is needed, evaluate CPET or other heat-resistant structures. Final confirmation always comes from the specific grade, thickness, structure and finished-pack testing.
First, the concepts: PET is a family; APET / BOPET / CPET are directions
| Direction | Typical character | Better suited to | DNW lamination focus |
|---|---|---|---|
| PET (family concept) | Family name for polyester materials; does not denote one fixed film performance | General term when describing PET-class materials/films | Confirm the specific type, orientation, thickness and structure |
| APET | Amorphous PET, usually with good clarity | Chilled, ambient and display food packaging | Clarity, dimensional stability, forming and seal matching |
| BOPET | Biaxially oriented PET film with oriented structure | Lid films, laminates, barrier/print layers for specific uses | Heat shrink, thermal stability, orientation and lamination temperature window |
| CPET | Crystallized PET, common in heat-resistant sheet/tray applications | Ovenable, freeze-to-heat tray scenarios | If used for lamination, confirm the exact film/sheet form and process compatibility |
Note: BOPET (biaxially oriented) is only one processing form of PET film and should not be conflated with APET sheet. When a customer asks for "PET film", engineers first confirm whether it is BOPET, APET or another PET-base film, mono-layer or laminate, and its thickness.
Film direction by application
| Application | Direction to evaluate first | Key point |
|---|---|---|
| Ambient / chilled / fresh display | APET or other transparent PET structures | Emphasize clarity, rigidity, appearance and chilled use |
| Clear lid film / appearance | BOPET and other transparent PET film structures (per use) | Do not equate BOPET with all "PET" |
| High-heat oven / freeze-then-bake | CPET or other validated heat-resistant structures | Stress specific grade + structure + finished-pack testing |
| Microwave heating | Dedicated heat-resistant structures; CPET/PP as the solution requires | Validate with the complete package under real microwave conditions |
| Heat sealing / MAP / VSP | Match the seal film to the tray's actual seal layer | Start from seal-layer matching, not the tray's base resin |
How to choose: a six-step flow
1. Confirm the maximum service temperature and dwell time; 2. Check for freeze-to-heat shock; 3. Confirm required functions: microwave, oven, heat sealing, MAP/VSP; 4. Confirm the pulp tray surface, moisture content, geometry and lamination method; 5. Select the specific film structure and thickness; 6. Validate the complete laminated package under real service conditions.
DNW lamination validation checklist (finished-pack level)
| Item | What it verifies | Recommendation |
|---|---|---|
| Lamination appearance | Uniform conformance, wrinkles, edge shrink, film rupture | Mandatory |
| Oil / water resistance | Core function of the fiber tray | Test with real food and time |
| Oven baking | Dimensional stability and film/pulp bond at high temperature | Per customer's actual temperature + time |
| Microwave | Hot spots, deformation, bulging, leaks | Per actual power + time |
| Freezing | Low-temperature embrittlement, cracking, delamination | Per customer's minimum temperature |
| Heat sealing | Seal strength, leaks, opening behavior | Matched to the actual lid/seal layer |
| Peel / opening force | Avoids "too hard to open" or "too easy to open" | Set an internal window, not just higher-is-better |
| Dimensional stability | Post-heat warping or shrinkage causing seal failure | Test in finished-pack state |
Data & limits
Heat resistance cannot be reduced to one universal number: it varies significantly with grade, orientation/crystallinity, thickness and service conditions. The dimensional and structural stability of the pulp substrate under high temperature and humidity also requires validation. All directional conclusions here are subject to real-condition testing of DNW-laminated finished packs.
Working with DNW engineers
Provide the food type, temperature profile, sealing method and pulp tray samples — we help evaluate film structure and lamination process, and deliver a production-ready recommendation.
Related reading: [Heating technology](/en/engineering/heating.html) · [Heat-seal performance](/en/performance/heatseal.html) · [Fresh meat application](/en/applications/fresh-meat.html) · [MAP packaging](/en/applications/map.html)