Summary: UV LED curing uses a wavelength (commonly 395 nm) to start photopolymerisation; dose = irradiance x time. LED power, distance and line speed must match film thickness and pigment absorption, else surface-dry/soft-inside or over-cure.
Mechanism
Dark/pigmented films absorb/shield UV and need more energy or multi-lamp/double-side; too little energy gives low crosslink density and poor chemical resistance.
Key data
- Typical UVA-LED 395 nm must match the photoinitiator's absorption.
- Dose is in mJ/cm2; both under- and over-dose hurt performance.
- Higher line speed needs more power or longer exposure to hold dose.
Matching
| Variable | Result |
|---|---|
| Under-dose | Skin-cure, soft inside, poor chemical |
| Over-dose | Yellowing, brittleness, energy waste |
Defects & fixes
- Soft inside: low energy / big distance — raise dose.
- Deep tackiness: pigment shielding — multi-lamp/double-side or thinner.
- Yellow/brittle: over-exposure — match power/speed.
FAQ
Why LED over mercury?
Cold cure, low energy, no ozone, instant on/off, good for thin wood parts.
Why is dark hard to cure?
Pigments absorb/shield UV; need higher dose or angled exposure.
How to set energy?
Small-sample by thickness, colour, initiator and line speed to find the window that hits hardness and chemical.
Ref: UV/LED photopolymerisation and dose matching (public).
Kexin New Materials (Guangdong) Co., Ltd. · 2026-09-18