Paint & Coatings Industry - April 2008 - (Page 32)

Designing UV-Curable Materials For High-Temperature Optical oatings for optical fiber have traditionally had stringent requirements regarding resistance to a number of environmental factors including heat, humidity and extremes of temperature. In addition to this, the cure speed demands of the fiber draw process have been amongst the most stringent in the UV/EB-curing industry, often with line speeds exceeding 1500-2000 meters per minute. Industry standards are in place for accelerated aging performance of fibers in telecommunications cable at 85 °C, 85 °C/85% relative humidity and temperature cycling from –65 to 85 °C. Among the main properties being monitored in these aging tests is how resistant the fiber is to transmission or “attenuation” loss after aging. Stresses in the coating due to thermal transitions, embrittlement or polymer chain scission due to thermo-oxidation and/or volatilization of unbound components can lead to small-radius bends in the fiber or micro-bending, which can result in a less than ideal path for light transmission. In addition, certain polymeric materials used as protective coatings on the fiber or in the cable can generate hydrogen gas at higher temperatures and, if the hydrogen is allowed to migrate into the glass itself, can create areas that actually absorb the wavelengths of light being transmitted. This process is known as TABLE 1 | Secondary coating chemistries. ID UA-1 Aliphatic polyether No. 1 UA-2 Aliphatic polyether No. 2 UA-3 Aliphatic polyether/ polyester UA-4 Isocyanate/ hydroxyethyl acrylate UA-5 Isocyanurate UA-6 Aliphatic polycarbonate UA-7 Aliphatic polyether No. 3 UA-8 Aliphatic polyether No. 4 UA-9 Aliphatic polyether No. 5 EA-1 Bisphenol-A epoxy diacrylate AM-1 IBOA AM-2 HDODA AM-3 Propoxylated NPGDA AM-4 DPGDA PI α-hydroxy ketone photoinitiator AO Bis-phenolic antioxidant C darkening of the fiber. These and other factors make the design of rapidly curing coating materials a challenge for higher temperature applications. New Optical Fiber Application A newer application for optical fiber is in the subterranean exploration of oil deposits. These are commonly referred to as “downhole” or “geophysical” applications. Since 1993, optical fiber has been used to sense conditions such as temperature, pressure and chemical environment (pH) in oil wells at distances up to at least 30 kilometers. In the past, performing these measurements with standard electrical sensing technology has proven difficult, due to the need of regenerating the electrical power for these distances. There are an estimated 200 fiber optic P&T (pressure and temperature) gauges and 40 downhole fiber optic flow meters installed as of the early part of 2007.1 Fiber optic sensors have improved the ability to “see” oil deposits from the surface and have enabled more efficient draining of the deposits once found. In a downhole fiber application, the well temperatures can range from near ambient to between 90-250 °C.2 As such, standard acrylate-coated optical fiber will not work for this entire service range, SC-1 SC-2 SC-3 SC-4 SC-5 SC-6 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • By Daniel A. Wilson, Fiber Optic Materials Development Manager; Matthew M. Ellison, Senior Scientist | Hexion Specialty Chemicals, Cincinnati, OH; and Zhang Xiaoyan, Technical Staff Member | Hexion UV Coatings, Shanghai, China 32 APRIL 2008 | W W W . P C I M A G . C O M http://WWW.PCIMAG.COM

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Paint & Coatings Industry - April 2008 Contents Viewpoint Industry News Calendar of Events Company News Mergers and Acquisitions Names in the News Snapshots of Success – Automotive Applications Designing UV-Curable Materials for High-Temperature Optical Fiber Applications The Future of UV Coatings is Now! Milling Media Review Part 1 – Bead Density Effect Preparation and Properties of UV-Curable Polyurethane Acrylate Resins for Metal Surfaces Conquering Color Harmony High-Performance PU Crosslinkers for Two-Component Waterborne Applications Decorative Film Laminates How Long Will the Gilding Glitter? Gaining a Competitive Advantage Using Benchmarking Supplier Showcase Materials Watch Products and Literature Classifieds Advertiser Index Automotive Color Trends New England Museum Solves Century-Old Vanderbilt Mansion Mystery

Paint & Coatings Industry - April 2008

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