UV absorbers are additives used in plastics to protect polymers from UV-induced degradation such as discoloration, brittleness, loss of strength, surface cracking, and reduced lifespan. They act by absorbing harmful ultraviolet radiation and converting it into harmless heat before it can attack the polymer chain.

Why Plastics Need UV Protection

Exposure to sunlight causes:

Chain scission (breakdown of polymer chains)

Fading of colorants

Loss of mechanical strength

Surface chalking and cracking

UV absorbers significantly extend the outdoor durability and lifetime performance of plastics.

Main Types of UV Absorbers
1. Benzotriazole UV Absorbers

Most widely used; excellent for outdoor applications.
Works for: Polycarbonate (PC), PET, PMMA, PVC, PU, coatings, adhesives.
Examples:

UV-328

UV-326

UV-531

UV-234

Tinuvin 327, 328, 329 (commercial BASF grades)

2. Benzophenone UV Absorbers

Cost-effective, moderate performance.
Works for: PVC, acrylics, polystyrene, polyolefins.
Examples:

BP-3 (Oxybenzone)

UV-531

BP-12

3. Triazine UV Absorbers

High thermal stability; excellent for engineering plastics requiring high-temperature processing.
Works for: PET, PBT, PC, PA, high-end coatings.
Examples:

UV-1577

UV-1600

4. Hindered Amine Light Stabilizers (HALS)

Not UV absorbers, but often used together for synergistic protection. They neutralize free radicals formed during UV degradation.
Works for: PP, PE, polyurethane, automotive plastics.
Examples:

HALS 770

HALS 944

Tinuvin 123, 622

Which Plastics Commonly Use UV Absorbers?

Polypropylene (PP)

Polyethylene (HDPE/LDPE)

Polycarbonate (PC)

PVC

ABS

Nylon (PA)

PET, PBT

Acrylic (PMMA)

Polyurethane (PU)

Used in: automotive parts, packaging, outdoor furniture, agricultural films, electrical housings, fibers, coatings, and adhesives.

Choosing the Right UV Absorber

Consider:

Type of polymer

Processing temperature

Exposure intensity (sunlight, heat, moisture)

Desired life expectancy

Color stability requirements

For highest outdoor protection, a blend of benzotriazole absorber + HALS is commonly used.

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