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Organic Protective Coatings- with examples Print E-mail


Coating is a covering that is applied to an object. The aim of applying coatings is to improve surface properties of a bulk material usually referred to as a substrate. One can improve amongst others appearance, adhesion, wetability, corrosion resistance, wear resistance, scratch resistance, etc.. They may be applied as liquids, gases or solids. To protect equipment from environmental damage; many paints, coatings and high performance organic coatings have been developed. Of prime importance in the development of protective coatings was the petroleum industry that produced most of the basic ingredients from which most synthetic resins were developed.

The cracking of petroleum produced a multitude of unsaturated workable compounds that are important in the building of large resin polymers such as vinyls and acrylics. The solvents necessary for the solution of the resins were also derived from petroleum or natural gas. The building blocks for epoxies and modern polyurethane coatings are other derivatives produced by refining petroleum products. Some important  concepts for designing corrosion resistant coatings are 

  • Coating protection
  • Component design
  • Component function
  • Coating formulation
For example, Zero Discharge Organic Coatings project developed powder paint, Ultraviolet (UV) curable paint, and electro- coating (E-coat) paint for military Applications. These technologies offer potential for high performance coatings with little or no volatile organic compound (VOC) emissions or hazardous waste generation.

Many steel structures built in marine environment were mainly protected by organic coatings. For saving the life cycle cost (LCC) of these structures, it is very important to predict the lifetime of those. About 25 kinds (n = 2) of organic coated steel pipes were exposed at seashore at Miyakojima Island in OKINAWA for 20 years and were evaluated the degradation of coated materials.
The obtained results are as follows                      (From- Science Links Japan)
  • Some monitoring techniques measured at exposure site were not effective for predicting the degradation of organic coating materials. A new monitoring technique to evaluate degradation will be expected.
  • A correspondence between the exposure results and laboratory acceleration test results was examined. It is shown that the rusted area spread from scratched portion exposed at splash zone correlates the rust width in SST, and also changes in adhesion strength of the tidal and submerged zone correlate with those of rotating immersion test. So, the preferable acceleration test can predict the degradation of organic coatings, in the case of having the similar environmental condition.
  • Maximum corrosion depth under the defect portion of organic coating was measured after removal the coating and rust. The maximum depth of submerged zone was deeper than those of tidal and splash zone. These phenomena were affected by macro cell formation, which consisted of sound coating as cathode and defect part as anode. The degradation of organic coated steel in marine environment should be considered the effect of macro cell formation.
 
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