Coating materials for ultraviolet optical fibers and cables

UV-curable acrylate, urethane acrylate, epoxy acrylate, silicone acrylate, polyimide, and carbon coatings are commonly used to protect optical fibers and cables under mechanical, thermal, and environmental stress. UV-Curable CoatingsUV-curable coatings are widely used for optical fibers due to their rapid curing, excellent mechanical properties, and adaptability to dual-layer or single-layer systems. A dual-layer system typically consists of a soft primary coating that cushions the fiber and a hard secondary coating that provides mechanical protection and environmental resistance.

Single-layer coatings combine these properties but may have limitations in microbending protection and ease of stripping compared to dual-layer systems. Common UV-curable prepolymers include: Urethane acrylates (UA): Provide flexibility and low modulus for the primary coating. Epoxy acrylates (EA): Offer high tensile strength and chemical resistance, suitable for secondary coatings.

Silicone acrylates (SA): Resistant to moisture and chemicals, often used in specialty fibers.

High-

Temperature and Specialty CoatingsFor fibers exposed to harsh environments, high-temperature resistant acrylates and polyimide coatings are used. These coatings can withstand continuous temperatures up to 275°C and short-term excursions up to 450°C, making them suitable for industrial sensing, aerospace, and military applications. Other specialty coatings include: Fluoroacrylates: Non-toxic, rugged, and ideal for medical applications; they improve tensile strength and retard static fatigue.

Silicone coatings: Soft, water- and chemical-resistant coatings that require buffering with thermoplastics like ETFE or PEEK for mechanical protection. Carbon coatings: Extremely thin layers that enhance fiber lifetime and can be combined with other coatings for additional protection.

Coating Structure and Performance

The primary coating directly contacts the glass fiber, dispersing external forces and providing adhesion. It typically has a low modulus of elasticity. The secondary coating surrounds the primary layer, offering mechanical strength and environmental protection with a higher modulus of elasticity.

Dual-layer coatings optimize microbending resistance, thermal stability, and long-term durability, while single-layer coatings simplify processing but may compromise some mechanical properties.

Cable Jackets and Buffers

Beyond fiber coatings, optical cables include buffers and jackets to protect fibers from environmental damage. Common jacket materials include: LSZH (Low Smoke Zero Halogen): Safe for enclosed installations.

PV

C: Flexible, low-cost, and suitable for indoor/outdoor use.

TP

U (Thermoplastic Polyurethane): High abrasion resistance, elasticity, and chemical resistance.

PVD

F: Excellent chemical and abrasion resistance, suitable for plenum-rated cables.

Summary

Selecting the appropriate coating for UV optical fibers depends on the application environment, temperature range, mechanical stress, and chemical exposure. UV-curable acrylates, urethane acrylates, epoxy acrylates, silicone acrylates, polyimide, and carbon coatings provide a range of solutions for telecommunications, industrial sensing, medical, and aerospace applications, ensuring fiber durability, mechanical protection, and long-term performance.