Epoxy-polyamide coatings properties

Standish, J. V., Leidheiser, Jr., H. The effect of water on the dielectric properties of a corrosion-protective epoxy-polyamide coating, ACS Div. Org. Coat. Plast. Chem. Prepr. 43, 565(1980)... 

In addition, the film has a long life and is resistant to the water, solvents, chemicals, acids, and alkali normally found in chemical and industrial environments. The epoxy-polyamide coatings have less resistance to strong solvents than do amine-cured systems, and their heat resistance tends to be somewhat lower. The properties of these coatings have been described in detail in several publications (32. 33). 

Coating formulations and properties have been detailed in technical bulletins (31). The epoxy-polyamide system is popular because it provides an unusual degree of inherent corrosion resistance. This will be discussed in detail later. The system is unusually tolerant as compared to related systems, such as amine cured, since the ratio of components is not particularly critical. Tolerance is also demonstrated because it may be applied to wet surfaces and to surfaces with tightly bound rust. Indeed, formulations are available that may be applied under water to structures such as submarines and off-shore oil well riggings. Both the corrosion resistance and the tolerance relative to application on poorly prepared wet surfaces are believed to be functions of the surface activity of the polyamide resin. Related also to the surface activity are the unusually strong adhesive properties that the system demonstrates with a broad range of substrates. 

Thicker epoxy-based coatings, highly flexibllized with amine-reactive nitrile liquid polymer, have been described by Mendelsohn (50) in which the flexibilizing hardener is comprised of an admixture of ATBN, fatty polyamide and boron trifluoride/amine complex. This coating ages well at 100°C and has excellent toughness/ flex with good abrasion and vibration absorption properties. 

Varelidis P C, Papakostopoulos D G, Pandazis C I and Papaspyrides C D (2000) Polyamide coated Kevlar fabric in epoxy resin mechanical properties and moisture absorption studies, Compos Part A 31 549-558. 

Much attention has been paid to the synthesis of fluorine-containing condensation polymers because of their unique properties (43) and different classes of polymers including polyethers, polyesters, polycarbonates, polyamides, polyurethanes, polyimides, polybenzimidazoles, and epoxy prepolymers containing pendent or backbone-incorporated bis-trifluoromethyl groups have been developed. These polymers exhibit promise as film formers, gas separation membranes, seals, soluble polymers, coatings, adhesives, and in other high temperature applications (103,104). Such polymers show increased solubility, glass-transition temperature, flame resistance, thermal stability, oxidation and environmental stability, decreased color, crystallinity, dielectric constant, and water absorption. 

To tackle the problem of fuel loss through the tank walls, polar barrier layers were tested. Among the methods tried were fluorination and sulfonation, as well as epoxy resin or polyamide powder coatings on the fuel tank walls. Again, cost and process safety were the issues begging for solutions, and fluorination and sulfonation proved to be the processes of choice for enhancing barrier properties. Both inline and offline processing approaches were tested, and fluorination with fluorine... 

Features Curing agent for maintenance and marine coatings, overprint varnishes, masonry and pool coatings, adhesives, caulks, grouts flexibilizer for thermoplastic polyamides Properties Gardner 9 max. sol n. dens. 7.6 Ib/gal vise. (G-H) W-Y amine no. 51-57 pot life 18 h (250 g) 59-61% solids in IPA/toluene Use Level 100 phr with epoxy resin of EEW=525 Epikure 3100-HX-60 [Resolution Perl. Prods.]... 

Uses Mfg. of block copolymers incl. polyamides, PU, PC mfg. of silicone-modified epoxy resins in corrosion-resist, coatings and polishes Features Improved adhesion to painted and unpainted metal surfs. Properties Liq. sp.gr. 0.98 vise. 50 cSt 98% solids PS513 [United Chem. Tech.]... 

Uses Polyamide for curing epoxy resins in adhesives, coatings, and sealants food pkg. adhesives, coatings Regulatory FDA 21CFR 175.105,175.300 Properties Gardner 7 liq. dens. 8.0 Ib/gal vise. 700-900 cps amine no. 

Properties Misc. with water m.w. 114.19 sp.gr. 0.94 b.p. 183 C (760 mm) flash pt. 167 F Toxicology LDLo (oral, rat) 1 g/kg LCLo (inh., rat, 4 h) 3200 mg/m si. toxic by ing. and inh. primary skin irritant TSCA listed Precaution Corrosive liq. combustible Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx Uses Epoxy curing agent chelating agent for oil field, textile, water treatment, detergent fields herbicide intermediate polyamide resins for adhesives, films, plastics, inks PU for extenders catalysts scale/corrosion inhibitors coatings... 

Dimer acids are used mainly as polyamides. Non-reactive polyamides, produced from dimer acids and diamines in stoichiometric amounts, are flexible and tough and have excellent adhesive properties. They are used as shoe adhesives, in printing inks, for surface coatings and in textile applications. Reactive polyamides, with free amine groups which can react further, are used as components of thermosetting epoxy systems in surface coatings. 

For the organic and composite materials (filled and unfilled epoxies, NEMA G-10 and FR-5 glass-epoxy composites, Nomex polyamide paper, Kapton polyamide film, and Formvar coating) tested, neither mechanical nor electrical properties are appreciably degraded by a gamma dose of 2 MGy at 5 K. 

Organic coatings include phenol formaldehyde, epoxy, polyacryl and polyacryl acid resins, polyamide, polyolefin, bitumen and rubber. The required properties of lining materials in combination with cathodic protection are given in Section 5.2.1. In addition, adequate resistance to water vapor diffusion is required (see Section 5.2.2). These properties are discussed in the basic standard for internal cathodic protection [2], which also reports how these properties can be assured by testing with the aid of Ref. 3. It is convenient to limit the protection potential region to [7 5 = -0.8 V in the presence of resin coatings, which makes potential-controlled protection current equipment necessary. 

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