- Email: [email protected]
European Coatings Congress — Poster Presentations
FOCUS mathematically, and the results indicate that the amount of pigment has only a limited effect on the short wave pattern of the powder coated surface, although the long wave roughness is strongly affected. Above a critical pigment concentration of 45 wt%, further pigment addition gives a significant increase in the height of the surface roughness. These results demonstrate that for a given pigment system the most effective way to improve the gloss is by reducing the long wave roughness. This can be achieved by reducing the pigment loading. Good correlation of the results was obtained at both 60° and 20° readings. A two-scale model evaluation is essential in predicting the effect of surface topography on gloss properties. Article entitled “A Mechanistic Study of the Effect of Pigment Loading on the Appearance of Powder Coatings: The Effect of Surface Topography on the Optical Properties of Powder Coatings: Modelling and Experimental Results” by researchers at DSM Research, published in Progress in Organic Coatings, Apr 2011, 70 (4), 206-212
European Coatings Congress – Poster Presentations In addition to the Congress papers, there were 14 poster presentations given during the evening of the first day of the European Coatings Show. Some interesting items are abstracted here. For further information see http://www.european-coatingsshow.com/en or email [email protected].
1. Development of radiation and corrosion resistant coatings for centrifugal extractors Centrifugal extractors driven by electric motors are widely used in the reprocessing of spent fuels of Fast Breeder Reactors. The rotors and stators of the motors are made from stampings of silicone steel and are continuously exposed to radiation and nitric acid fumes. PEEK (polyetheretherketone) was selected for the coating of rotors, MAY 2011
ON
POWDER
as a high performance engineering plastic, with a radiation resistance of 109 rads and resistance to a wide range of chemicals at elevated temperatures in harsh environments. A 0.5 micron film was applied to the rotors and was assessed for hardness, electrical resistance and testing in the corrosive environment. It was confirmed to give suitable protection to the rotor components. The stators, however, could not be protected by the PEEK coating since the stator components could not withstand the high stoving temperature of 390°C for PEEK. An epoxy powder coating was applied and found to give the required chemical resistance to the stators. Felix Lawrence, Indira Gandhi Centre for Atomic Research, India
2. Coating comprising covalently bound selenium preventing biofouling and corrosion Hydraulic fracturing, involves sending high pressure fluid containing sand through a well bore deep in an oil/gas bearing shale formation to cause fracture. This is followed by an injection of sand or ceramic bead proppants, which are lodged inside the shale to keep the fracture open. The fractured shale allows free flow of natural gas and oil into the pipeline conveying them to the surface for collection. Environmental problems are occurring due to the contamination of aquifers by the extensive use of conventional biocidal agents. Anaerobic ironand sulfate-degrading bacteria rapidly proliferate in the fracturing fluids, causing corrosion of the pipes and clogging of the proppants. A biocidal solution to the problem should be environmentally friendly and must not freely diffuse away from the bore hole. Covalently bound selenium is claimed to be preferable to the use of copper and silver biocides because it remains permanently attached to
C O AT I N G S a surface while remaining biologically active. It is FDA approved and releases reactive oxygen species such as hydrogen peroxide to kill the bacteria. The effect is short range and does not extend far from the coated surface. It is suggested that covalent selenium will find numerous uses in the coatings industry in the future. Jonathan Matias, Poseidon Sciences Group, USA
3. Surface Chemistry of Epoxy Coatings & its Relationship to 21 Pathogenical Microorganisms Surgical devices are obviously cleaned frequently to remove any microorganisms, but many coatings patents have been claimed to offer protection. However, it has been shown that some of these formulations were more prone to re-infection than others. Many of these formulations were based on epoxy chemistry, including liquids, powder coatings, pure epoxy, phenolic epoxy, and epoxy polyester. A study was made of the surface chemistry of each coating using an electron microscope. Some formulations were found to show microscopic porosity large enough to house some bacterial spores, viruses and prions. It was also found that different surface additives produced different degrees of microporosity, and it was concluded that spongiforme microporosity should be avoided, while the formation of punctiforme microscopy should be promoted. Micro sponge holes make it impossible for chemical sterilants to reach bacteria allowing microorganisms to remain hidden. Punctiforme microporosity appears as open tiny craters, which makes them more accessible to sterilants. This study showed that there are several significant differences in surface chemistry from one type of epoxy to another, and this should be taken into account when creating hospital coatings, especially those 3
European Coatings Congress – Poster Presentations In addition to the Congress papers, there were 14 poster presentations given during the evening of the first day of the European Coatings Show. Some interesting items are abstracted here. For further information see http://www.european-coatingsshow.com/en or email [email protected].
1. Development of radiation and corrosion resistant coatings for centrifugal extractors Centrifugal extractors driven by electric motors are widely used in the reprocessing of spent fuels of Fast Breeder Reactors. The rotors and stators of the motors are made from stampings of silicone steel and are continuously exposed to radiation and nitric acid fumes. PEEK (polyetheretherketone) was selected for the coating of rotors, MAY 2011
ON
POWDER
as a high performance engineering plastic, with a radiation resistance of 109 rads and resistance to a wide range of chemicals at elevated temperatures in harsh environments. A 0.5 micron film was applied to the rotors and was assessed for hardness, electrical resistance and testing in the corrosive environment. It was confirmed to give suitable protection to the rotor components. The stators, however, could not be protected by the PEEK coating since the stator components could not withstand the high stoving temperature of 390°C for PEEK. An epoxy powder coating was applied and found to give the required chemical resistance to the stators. Felix Lawrence, Indira Gandhi Centre for Atomic Research, India
2. Coating comprising covalently bound selenium preventing biofouling and corrosion Hydraulic fracturing, involves sending high pressure fluid containing sand through a well bore deep in an oil/gas bearing shale formation to cause fracture. This is followed by an injection of sand or ceramic bead proppants, which are lodged inside the shale to keep the fracture open. The fractured shale allows free flow of natural gas and oil into the pipeline conveying them to the surface for collection. Environmental problems are occurring due to the contamination of aquifers by the extensive use of conventional biocidal agents. Anaerobic ironand sulfate-degrading bacteria rapidly proliferate in the fracturing fluids, causing corrosion of the pipes and clogging of the proppants. A biocidal solution to the problem should be environmentally friendly and must not freely diffuse away from the bore hole. Covalently bound selenium is claimed to be preferable to the use of copper and silver biocides because it remains permanently attached to
C O AT I N G S a surface while remaining biologically active. It is FDA approved and releases reactive oxygen species such as hydrogen peroxide to kill the bacteria. The effect is short range and does not extend far from the coated surface. It is suggested that covalent selenium will find numerous uses in the coatings industry in the future. Jonathan Matias, Poseidon Sciences Group, USA
3. Surface Chemistry of Epoxy Coatings & its Relationship to 21 Pathogenical Microorganisms Surgical devices are obviously cleaned frequently to remove any microorganisms, but many coatings patents have been claimed to offer protection. However, it has been shown that some of these formulations were more prone to re-infection than others. Many of these formulations were based on epoxy chemistry, including liquids, powder coatings, pure epoxy, phenolic epoxy, and epoxy polyester. A study was made of the surface chemistry of each coating using an electron microscope. Some formulations were found to show microscopic porosity large enough to house some bacterial spores, viruses and prions. It was also found that different surface additives produced different degrees of microporosity, and it was concluded that spongiforme microporosity should be avoided, while the formation of punctiforme microscopy should be promoted. Micro sponge holes make it impossible for chemical sterilants to reach bacteria allowing microorganisms to remain hidden. Punctiforme microporosity appears as open tiny craters, which makes them more accessible to sterilants. This study showed that there are several significant differences in surface chemistry from one type of epoxy to another, and this should be taken into account when creating hospital coatings, especially those 3