Medical Bag TPU | Welding, Seal Reliability & Long-Term Storage Stability
Medical Bag TPU
TPU material selection for medical fluid bags (storage bags, infusion bags, and related flexible containers),
where the core requirement is welding and seal reliability plus appearance consistency and long-term storage stability.
This page focuses on practical selection logic, common sealing risks, and process adaptation for film/sheet forming + welding routes.
Many medical bag projects fail not because “TPU cannot weld”, but because the system is not balanced for
seal strength, seal durability, clarity stability, and long-run process repeatability.
A robust bag TPU must support stable welding behavior across real production conditions.
seal strength, seal durability, clarity stability, and long-run process repeatability.
A robust bag TPU must support stable welding behavior across real production conditions.
Welding / Sealing
Seal Durability
Long-Term Storage Stability
Transparency / Appearance
Film / Sheet Forming
Process Repeatability
Seal Durability
Long-Term Storage Stability
Transparency / Appearance
Film / Sheet Forming
Process Repeatability
Typical Applications
- Medical storage bags – flexible containers requiring stable sealing integrity and consistent appearance.
- Infusion / fluid delivery bags – projects sensitive to seal durability and long-run quality repeatability.
- Functional medical flexible containers (project-dependent) – structures requiring specific forming and welding behavior aligned to internal validation needs.
Quick Grade Selection (Shortlist)
Choose “Seal-Focused” when
- Welding behavior and seal integrity are the #1 risk
- You need stable seal strength across production variation
- Durability under handling and transport matters (project-dependent)
Choose “Clear & Stable” when
- Clarity and appearance consistency are strict requirements
- Long-term storage needs stable appearance without drift
- You want a wider forming and welding processing window
Note: Final selection depends on film/sheet thickness, bag structure (layers, ports, seams), welding method, and your verification plan (project-dependent).
Common Failure Modes (Cause → Fix)
In medical bag manufacturing, most failures come from interactions between material, forming conditions, and welding discipline. Use the table below as a quick diagnostic:
| Failure Mode | Most Common Cause | Recommended Fix |
|---|---|---|
| Seal leakage / weak seams | Welding window too narrow; contamination; insufficient fusion | Choose a seal-focused family; tighten cleanliness; stabilize welding temperature/pressure/time and fixturing |
| Seal becomes brittle or fails after aging | Material route not positioned for long-term retention; heat history too aggressive | Choose long-term stability direction; reduce overheating; validate after storage/aging (project-dependent) |
| Appearance drift (haze, gloss change, color shift) | Moisture, degradation, or inconsistent melt history during film/sheet forming | Dry thoroughly; stabilize forming profile; tighten heat/shear control; improve material handling discipline |
| Warping / forming instability affects welding | Sheet/film forming not stable; thickness variation drives uneven weld energy | Stabilize thickness; tune cooling and take-off; ensure welding fixturing matches the formed geometry |
For medical bags, “good welding” is a system result: stable film/sheet + stable welding window + stable material behavior.
The goal is not only strong seams, but repeatable seam quality across long runs and storage time.
The goal is not only strong seams, but repeatable seam quality across long runs and storage time.
Typical Grades & Positioning
| Grade Family | Hardness | Design Focus | Typical Use |
|---|---|---|---|
| TPU-MED BAG Seal-Focused | 80A–98A | Welding behavior and seal integrity direction with stable seam durability | Medical bags where leak risk and seam durability dominate |
| TPU-MED BAG Clear & Stable | 75A–55D | Clarity and long-term appearance stability direction with repeatable forming and welding window | Bags requiring consistent appearance and stable storage behavior |
Note: Positioning is application-focused. Final selection depends on bag structure, forming route, welding method, and validation plan (project-dependent).
Key Design Advantages
- Welding and sealing reliability focus to reduce leak risk and improve seam repeatability.
- Seal durability direction for handling, transport, and storage time sensitivity (project-dependent).
- Transparency and appearance consistency direction to reduce haze drift and visual variation across lots.
- Forming + welding process compatibility designed for stable production windows on film/sheet routes.
Processing & Recommendations (3-Step)
1) Stabilize Film / Sheet
Uniform thickness and stable geometry are the foundation. Thickness drift often becomes sealing instability later.
2) Control Cleanliness & Heat History
Cleanliness impacts welding quality. Avoid overheating and inconsistent heat history to keep clarity and sealing behavior stable.
3) Validate Seals Under Real Conditions
Validate seam integrity with your real welding method and fixturing. Include storage/aging scenarios if your project is sensitive (project-dependent).
- Welding window: Confirm the stable window for temperature/pressure/time rather than optimizing only one point.
- Seam geometry: Fixturing and seam design affect repeatability as much as resin choice.
- Long-term stability: If storage is critical, verify sealing performance after conditioning (project-dependent).
Is this page for you?
You will benefit most if:
- Your seams leak or show weak seal strength
- Your sealing quality varies across runs or shifts
- Your clarity/appearance drifts after forming or storage
- You need a shortlist aligned to sealing reliability and stable production
Request Samples / TDS
If you are developing medical bags and want to reduce trial risk,
contact us for a recommended grade shortlist and technical data sheets based on your bag structure,
film/sheet thickness and welding method.
To get a fast recommendation, send:
- Bag type and structure (layers, ports, seam design, project-dependent)
- Film/sheet thickness range and clarity / appearance targets
- Welding method and parameters (RF/heat/ultrasonic, project-dependent), plus current failure symptoms
- Storage and validation focus (aging, seam durability, appearance stability, project-dependent)
