Anticorrosive epoxy

High build, anticorrosive epoxy 61 125-150 2 h 3 h Two components, for land and marine structures, unlimited overcoating time, good impact resistance and flexibility... 

Corrosion. Anticorrosion measures have become standard ia pipeline desiga, coastmctioa, and maintenance ia the oil and gas iadustries the principal measures are appHcation of corrosion-preventive coatings and cathodic protection for exterior protection and chemical additives for iaterior protectioa. Pipe for pipelines may be bought with a variety of coatiags, such as tar, fiber glass, felt and heavy paper, epoxy, polyethylene, etc, either pre-apphed or coated and wrapped on the job with special machines as the pipe is lowered iato the treach. An electric detector is used to determine if a coatiag gap (hoHday) exists bare spots are coated before the pipe is laid (see Corrosion and corrosion control). 

Sulfonic acid salts have found widespread use in the area of corrosion inhibition. Lubrizol Corporation produces a wide variety of sulfonic acids, particularly in the form of magnesium salts, for use in lubricant formulations, anticorrosion coatings, greases, and resins (146,147). Petroleum sulfonates are used in epoxy resin elastomers to improve anticorrosion properties of coatings and sealants (qv) (148,149). 

Assuming maximum corrosion resistance is required, then an anticorrosive primer will be needed, with best protection coming from a crosslinked epoxy stoving primer. Most other properties are dominated by the finish, which will be based on a high molecular weight-polymer, either linear or (more usually) crosslinked. The precise selection of the polymer depends on the balance of properties required, but will be constrained by the type and rate of curing necessary. 

Epoxy-silica hybrids are well known for their abrasion resistance and low thermal expansion due to the presence of nanostructured bi-continuous domains. Most recently they have entered the market as anticorrosion coatings in the marine held, for yachts and for large metal vessels, such as oil tankers, and in particular for cargo or ballast tanks and on hulls (Figure 4.9). 

Uses. Production of methylene diphenyl diisocyanate (MDI), which is used to produce polyurethanes hardening agent for epoxy resins, anticorrosive materials, printed circuit parts, dyestuff intermediates, filament-wound pipe, and wire coatings... 

Uses. As a curing agent for epoxy and other resins and as a vinyl plasticizer also found in anticorrosive surface coatings, polymers, paints, dyes, and pharmaceuticals... 

Anticorrosive pigment Air- drying alkyd primers Alkyd- melamine primers 2-Compo- nent epoxy primers 2-Compo-nent acrylic isocyanate primers Chlor- inated rubber primer Aqueous polymer dispersions Poly(vinyl- butyral) primers Electro- deposition coatings Mirror coatings References... 

Use Anticorrosive pigment for solvent-based epoxies and as auxiliary pigment for 1-package zinc-rich coatings. Also used in water-based coatings. 

Use Alkyd, epoxy and other resins anticorrosive agents plasticizers wetting agents for bituminous compounds. 

Veleva, L., Chin, J., and del Amo, B., Corrosion electrochemical behavior of epoxy anticorrosive paints based on zinc molybdenum phosphate and zinc oxide, Progr. Org.Coat., 36, 211, 1999. 

A further progress perspective in the field of water-based paints could be their use for painting ships [205]. However, these studies are only in the beginning. The main difficulty is corrosion prevention. Maximum protection from stress corrosion cracking is ensured by alkyd paints combined with phenolic epoxy paints during a 6.5-year exposure [206]. These data were obtained on pre-contaminated steel plates. In Russia now water-based dispersion primers with anticorrosive properties have been developed and manufactured [207]. This was possible after incorporation of corrosion inhibitors combined with surfactants into the formulations. 

The binders for cathodic electrodeposition are epoxy resin combinations dispersed in water (see Section 3.8). Advantages of anticorrosive electrocoatings include excellent corrosion resistance at a dry film thickness of ca. 20-30 pm. Electrocoats are stoved at 165 -185 °C to obtain films with the desired properties. The paint industry is now developing electrocoats that can be cured at lower temperatures (140 150 "C). Electrocoating produces a homogeneous film that covers the entire car body surface, including recesses and cavities. 

Although two-pack epoxy primers and polyurethane intermediate coats have high solids contents, they still contain significant amounts (20-30 wt%) of organic solvents. In polyurethane topcoats, the VOC is even higher. Anticorrosive, waterborne primers based on aqueous dispersions of two-pack epoxy resins and one-pack acrylic resins have been developed to decrease solvent emission. Waterborne, one-pack acrylic topcoats are also used. All of these waterborne paints contain 2 - 5 % organic cosolvents that are required for film formation. 

Two-pack epoxy primers with chromate-free pigments show the best performance. They are applied with a DFT of ca. 80 pm, and simultaneously form the anticorrosive primer and a sandable filler. They can protect the metal substrates against corrosion. 

Anticorrosive primer formulations are based on epoxy resins that react at ambient temperature with amine adducts, aminoamide resins, or isocyanates (two-pack primers). Zinc or strontium chromates are used as anticorrosive pigments. These electrolytically active pigments prevent dangerous filiform corrosion. Extensive development work is being carried out on chromate-free aircraft primers [11.8], [11.9]. 

ZnO/CaSiOs and MgO/CaSi03), and their anticorrosive properties were compared in epoxy-ester-based paints. Results indicated that MgO exhibits higher anticorrosion efficiency than zincite (ZnO). Depending on the shape, the anticorrosion efficiency for zincite particles decreases in the order ... 

An advantage of incorporating ECPs into a binder such as epoxy or polyurethane is the good adhesion that such binders provide, and the actual performance of coatings based on formulation may be due to the fact that the adhesion is better than that obtained by electropolymerization. However, this strategy leads to less contact between metal and ECP and, in view of the protection mechanisms described in Section 16.2, this may be to the detriment of the anticorrosion properties. 

Liao, L. P Zhang, W. Xin, Y. Wang, H. M. Zhao, Y Li, W. J. Preparation and characterization of microcapsule containing epoxy resin and its self-healing performance of anticorrosion covering material. Chinese Science Bulletin (2011), 56(4-5), 439-443. 

Conventional vinyl ester resins are increasingly used in anticorrosion applications and in marine applications. They are essentially epoxy resins, but chemically modified to enable them to cure in just the same way, and with virtually the same chemicals and fabrication procedures as polyesters. They have excellent water resistance and chemical resistance, but poor resistance to UV light, although modifications can be made to make them light stable and suitable for use in weatherable gelcoats [13]. 

Chem. Descrip. Polyamidoamine (70%) in xylene Uses Crosslinking agent for epoxy resins in soiv.-based primers and coatings for min. and metallic substrates, anticorrosion primers, zinc-rich primers, coatings for lock gates, concrete, and underground conduits (in combination with tar)... 

Uses Epoxy tiexibiiizer/diiuent, acid resist, aid, vise, reducer in fioor and surfacing compds., VOC-compiiant surf, coatings, tooiing resins, adhesives, eiec. appiics., anticorrosive coatings tor marine and industriai... 

---