High Performance Coatings              

INTRODUCTION

Polyurethanes are perhaps the most versatile polymers. Materials with a wide variety of physical and chemical properties can be formulated from the many commercially available and relatively inexpensive polyisocyanates and polyols. Polymers with block, comb, or random morphologies are produced by careful selection of reaction conditions, and the materials may take any form from brittle glasses to elastomers.

Introducing Fluorine into polyurethane resins brings about changes in properties similar to those seen when other polymers are fluorinated. Chemical, thermal, hydrolitic, and oxidative stability are enhanced, and the polymer becomes less permeable to oxygen. Surfaces become more biocompatible and less able to bond to substances in contact with them.

Fluorourethanes are widely used in modern chemical technology. They are used in products ranging from hard, heat-resistant electrical components to biologically compatible surgical adhesives. Perhaps the largest use of fluorourethanes is in surface coatings for
industrial and architectural structures, automobiles, ships and aircraft. Fluorourethanes are also used widely in medical products and as surface enhancing treatment for textiles, leather and carpets.

FPU’s® surface is composed of closely packed trifluoromethyl groups and exhibits the lowest surface energy known, 6mJ/m2.

FPU® exhibits not only the hardness and toughness of conventional polyurethane coatings but also the low surface energy and easy cleanability of PTFE. The coating also demonstrates excellent color and gloss stability and resistance to weather and corrosion. Clear coatings in flat, semigloss, or gloss finishes are available with FPU®, and custom colors are blended without difficulty.

A low energy coating readily allows the dispersion of PTFE as much as 38% by volume for applications in severe service environments. FPU® with PTFE additive is being used as an anti-corrosion coating on ships, bilges and tanks and as a non-toxic fouling-release coating on small boats. Fouling does occur but can be readily removed with ease.

FPU® is specified by the US Army and Navy for the interior of bulk fuel storage tanks.  Large tanks always contain water at the bottom which accumulates naturally from condensation. Fluorourethane linings resist attack by both fuel and water, which is more corrosive than the fuel. The low-energy surface of the lining also permits cleaning with high pressure water only; no detergent is required. Oily washings are processed in an oil-water separator and clear
water is deposited in a municipal sewer, thus avoiding the high cost of disposing large volumes of oily water.

Unpigmented coatings are used as clear, abrasion resistant, water shedding finish coats on submarine radomes. A radome is made more effective by a coating which allows water to drain rapidly from its surface, for films of water interfere with transmission and reception of signals.  Radomes must be retuned as water drains from their surface, and a strong and steady signal is obtained only when water is absent.