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Degradation behaviour of fusion bonded epoxy powder coatings
FOCUS simultaneous or “SIN” technique. This involves mixing together monomers, oligomers, crosslinkers and initiators and effecting polymerization and crosslinking simultaneously. The IPNs synthesized to date exhibit varying changes of phase separation depending primarily upon the compatibility or miscibility of the components present in the polymer mix. Phases, which vary in size, shape, sharpness and degree of continuity, have a profound effect on physical and mechanical properties such as the modulus and the glass transition temperature. A paper by Iranian researchers describes the preparation of a typical free radical curing powder coating and a cationic powder coating, using a variety of commercially available materials. These products were then blended at various weight ratios to prepare the IPN powder coatings. Neither of these coatings was pigmented. Each premix was then extruded at 80°C in a twin-screw extruder and then converted to powder. The applied coatings were subjected to IR heating for 100 seconds and then exposed to UV. Coatings were then postcured at 100°C for 5 hours. Tests on each powder included impact resistance; pendulum hardness, adhesion and MEK resistance, to ASTM standards. Salt spray resistance was also carried out and the Tgs were determined. Free radical and cationic curable powder coatings have very different crosslinking mechanisms. The double bond is opened by free radicals generated by the photoinitiator, or, in the case of cationic cure, the epoxy rings are opened by the cations generated by the UV radiation activated photoinitiators. The results of the tests carried out on the various blends are tabulated and comparisons are made of flow, cross hatch adhesion, direct impact and Konig hardness, including a standard 4
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thermally cured epoxy polyester hybrid. The free radical cured material alone has very low direct impact resistance, high Konig hardness, and poor cross hatch adhesion but the flow is good. The unmodified cationic UV cured material exhibits excellent direct impact resistance; poor Konig hardness; good cross hatch adhesion and good flow properties. The results obtained with the blends follow the trends of the two components. Salt spray resistances were also tabulated. The free radical UV cured powder coatings have higher crosslink densities than the cationic UV cured systems and the IPN coatings formulated with higher free radical UV cured component exhibited excellent salt spray resistance. This pattern also reflected the MEK resistance properties. This study does show that careful selection of the type and the amount of free radical and cationic components used to form IPN UV curable powder coatings can make it possible to engineer the required mechanical and physical properties. Paper entitled “UV-Curable Powder Coatings Containing Interpenetrating Polymer Networks (IPNs)” by Saeid Bastani and Siamak Moradian of the Polymer and Colour Departments of Amirkabir University of Technology, Iran published in Progress in Organic Coatings, Jul 2006, 56, (2-3), 248251
Degradation behaviour of fusion bonded epoxy powder coatings Fusion bonded epoxy (FBE) coatings have wide applications in flow handling components such as pipelines and hydraulic turbines. However, most organic coatings including FBE coatings are usually examined in static solutions in the laboratory. It was reported by Bierwagen that flowing electrolyte had a marked effect upon the performance of a coating system. A recent study by Chinese metallurgists seeks to clarify the impact of flowing corrosion on coating performance by setting up a rotating cylinder
C O AT I N G S device. In this set up the specimens move in the immersion test while the earlier work concentrated on moving the solution rather than the specimen. The use of a rotating cylinder makes it easier to estimate the flowing rate of the solution relative to the coating surface. A programme initiated by the Institute of Metal Research, Chinese Academy of Sciences has examined the degradation of three fusion bonded epoxy systems under flowing and static immersion conditions using electrochemical impedance spectroscopy (EIS) when exposed to 3% aqueous salt solution at 60°C. While this is not a standard test it does not alter the mechanism of degradation and simply serves to shorten the test period. EIS is considered to be a powerful tool for assessing the degradation of coatings since the impedance spectrum reflects dielectric behaviour, metal dissolution and oxidation-reduction reactions on the metallic substrate. Carbon steel panels of 6 x 6 x 0.4 cm were used in these tests. The edges of the panels were smoothed and electric contact was assured by soldering electric wire to the corner of the panel. The electric wire was taped to avoid corrosion. Panels were sand blasted to remove any mill scale and the coating applied immediately by electrostatic spray and cured at either 220°C for 10 minutes (Specimen 1) or 220°C for 40 minutes for specimens 2 and 3. The composition of each FBE specimen was tabulated in the article. Essentially each binder was based on the same epoxy resin, cured with dicyandiamide and 2 MI (Specimen 1) and dicyandiamide alone in the specimens 2 and 3. Specimens 1 and 2 contained silica and calcium oxide fillers, while specimen 3 used titanium dioxide as filler. Specimen 1 also included chromic oxide as a pigment while the other two contained carbon black pigment. AUGUST 2006
FOCUS All three contained the same amount of flow additive. Film thicknesses varied from 118 to 172 µm. Two panels of each were tested under static conditions and two panels were subjected to flowing conditions. Immersion experiments under flowing condition were carried out by a rotating system with the specimens mounted on the cylindrical surface of a cylinder, 500 mm in diameter and 80 mm in height, which rotated in a corrosive tank of 650 x 600 x 400 mm. The linear rate of the cylinder edge was about 18.3 m/min. The corrosive medium was NaCl solution and distilled water was added regularly to maintain the solution level. The solution temperature was kept at 60 ±2°C, with a heater controlled by a relay. Eight baffles were mounted around the cylinder to diminish the solution fluctuation. The immersion tests under static condition were simultaneously performed in this study. The specimens were periodically removed from the corrosion tank for EIS measurements. After removal, the specimens were immediately wrapped with plastic film to prevent water evaporation from the coatings. These specimens were then kept in air for about 15 minutes to cool the coatings down to room temperature. The article gives a full account of the corrosion tests and the results obtained from EIS measurements and visual examination showed that the exposure condition dramatically affected the degradation process of coatings. Flowing immersion resulted in much greater corrosion damage to the coatings than that of the static condition. The effect of flow on the degradation of the coating seems to involve ion rather than water diffusion in the coating and it confirms that the flowing test can be a novel means for examination of the protective performance of a coating. Article entitled “Comparison of the Degradation Behaviour of Fusion Bonded
AUGUST 2006
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Epoxy Powder Coating Systems under Flowing and Static Conditions” by Y H Wei and associates at the State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China, published in Corrosion Science, Jun 2006, 48 (6), 14491461
C O AT I N G S be expanded to reach up to 5000 tonnes/y at a later time. Buoyant sales of white goods and auto ancillaries is bolstering the powder coatings segment, which has a growth rate of 20%/y. European Paint and Resin News, Jun 2006, 44 (6), 11
INDUSTRY NEWS Acriton and Barpol sold to Industrias Titan Barpimo has sold two of its business units, Acriton and Barpol, to its national competitor, Spanish paint maker Industrias Titan. Acriton, produces architectural coatings, and Barpol, is a powder coatings maker. They posted a combined turnover of €13 M in 2005. European Paint and Resin News, Jun 2006, 44 (6), 4
Asian Paints gains from India’s construction boom Asian Paints’ sales grew 17.4% for the fiscal year ended 31 Mar 2006 on the back of a construction boom in India. Net sales for the year increased to Rup 30.2 bn (€522.08 M) as profit before tax and after goodwill rose by 19.2% to Rup 3.43 bn from Rup 2.878 bn the previous year. The company’s industrial business grew over 20% because of improved sales in automotive coatings, powder coatings and protective coatings. International paint sales grew 15.7% to Rup 5.3 bn. European Paint and Resin News, Jun 2006, 44 (6), 7-8
Asian Paints builds new powder coat factory in Baddi, India Asian Paints is setting up a new powder coatings factory at Baddi in Himachal Pradesh, India. The new plant will have an initial capacity of 1200 tonnes/y but will
Jotun has paint plans Norway based coatings manufacturer Jotun will build two powder coating and paint production plants in Pune, India, under a NKR 120 M (€15.1 M) investment. Construction of the factories will begin in 2007. The new powder coating and paint factories are scheduled to be on stream by 2Q 2008. ICIS Chemical Business, 10 Jul 2006, (Website: http://icischemicalbusiness.com)
Rohm and Haas 2Q 2006 results Rohm and Haas Co reported 2Q ending Jun 2006 sales of $2081 M (+5% over 2Q 2005) driven primarily by higher demand. For 2Q 2006, earnings from continuing operations were $192 M (earnings of $172 M in 2Q 2005). For 2Q 2006, sales in the Coatings segment were $739 M an increase of 4% over 2Q 2005. Architectural and Functional Coatings sales increased 4% for 2Q 2006. Powder Coatings sales were flat at $85 M for 2Q 2006. Monomer sales were $499 M during 2Q 2006 (+1% over $495 M in 2Q 2005). Sales of downstream Rohm and Haas speciality businesses were 8% higher during 2Q 2006. The Performance Chemicals sales were $452 M (+6% over 2Q 2005). Sales in Plastics Additives were up 9% for 2Q 2006 while, Consumer and Industrial Specialties sales increased 2%. Sales of Process Chemicals for 2Q 2006 were up 4%. For 2Q 2006, Electronic Materials recorded sales of $393 M (+21% over 2Q 2005). Semiconductor Technologies sales increased 5
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thermally cured epoxy polyester hybrid. The free radical cured material alone has very low direct impact resistance, high Konig hardness, and poor cross hatch adhesion but the flow is good. The unmodified cationic UV cured material exhibits excellent direct impact resistance; poor Konig hardness; good cross hatch adhesion and good flow properties. The results obtained with the blends follow the trends of the two components. Salt spray resistances were also tabulated. The free radical UV cured powder coatings have higher crosslink densities than the cationic UV cured systems and the IPN coatings formulated with higher free radical UV cured component exhibited excellent salt spray resistance. This pattern also reflected the MEK resistance properties. This study does show that careful selection of the type and the amount of free radical and cationic components used to form IPN UV curable powder coatings can make it possible to engineer the required mechanical and physical properties. Paper entitled “UV-Curable Powder Coatings Containing Interpenetrating Polymer Networks (IPNs)” by Saeid Bastani and Siamak Moradian of the Polymer and Colour Departments of Amirkabir University of Technology, Iran published in Progress in Organic Coatings, Jul 2006, 56, (2-3), 248251
Degradation behaviour of fusion bonded epoxy powder coatings Fusion bonded epoxy (FBE) coatings have wide applications in flow handling components such as pipelines and hydraulic turbines. However, most organic coatings including FBE coatings are usually examined in static solutions in the laboratory. It was reported by Bierwagen that flowing electrolyte had a marked effect upon the performance of a coating system. A recent study by Chinese metallurgists seeks to clarify the impact of flowing corrosion on coating performance by setting up a rotating cylinder
C O AT I N G S device. In this set up the specimens move in the immersion test while the earlier work concentrated on moving the solution rather than the specimen. The use of a rotating cylinder makes it easier to estimate the flowing rate of the solution relative to the coating surface. A programme initiated by the Institute of Metal Research, Chinese Academy of Sciences has examined the degradation of three fusion bonded epoxy systems under flowing and static immersion conditions using electrochemical impedance spectroscopy (EIS) when exposed to 3% aqueous salt solution at 60°C. While this is not a standard test it does not alter the mechanism of degradation and simply serves to shorten the test period. EIS is considered to be a powerful tool for assessing the degradation of coatings since the impedance spectrum reflects dielectric behaviour, metal dissolution and oxidation-reduction reactions on the metallic substrate. Carbon steel panels of 6 x 6 x 0.4 cm were used in these tests. The edges of the panels were smoothed and electric contact was assured by soldering electric wire to the corner of the panel. The electric wire was taped to avoid corrosion. Panels were sand blasted to remove any mill scale and the coating applied immediately by electrostatic spray and cured at either 220°C for 10 minutes (Specimen 1) or 220°C for 40 minutes for specimens 2 and 3. The composition of each FBE specimen was tabulated in the article. Essentially each binder was based on the same epoxy resin, cured with dicyandiamide and 2 MI (Specimen 1) and dicyandiamide alone in the specimens 2 and 3. Specimens 1 and 2 contained silica and calcium oxide fillers, while specimen 3 used titanium dioxide as filler. Specimen 1 also included chromic oxide as a pigment while the other two contained carbon black pigment. AUGUST 2006
FOCUS All three contained the same amount of flow additive. Film thicknesses varied from 118 to 172 µm. Two panels of each were tested under static conditions and two panels were subjected to flowing conditions. Immersion experiments under flowing condition were carried out by a rotating system with the specimens mounted on the cylindrical surface of a cylinder, 500 mm in diameter and 80 mm in height, which rotated in a corrosive tank of 650 x 600 x 400 mm. The linear rate of the cylinder edge was about 18.3 m/min. The corrosive medium was NaCl solution and distilled water was added regularly to maintain the solution level. The solution temperature was kept at 60 ±2°C, with a heater controlled by a relay. Eight baffles were mounted around the cylinder to diminish the solution fluctuation. The immersion tests under static condition were simultaneously performed in this study. The specimens were periodically removed from the corrosion tank for EIS measurements. After removal, the specimens were immediately wrapped with plastic film to prevent water evaporation from the coatings. These specimens were then kept in air for about 15 minutes to cool the coatings down to room temperature. The article gives a full account of the corrosion tests and the results obtained from EIS measurements and visual examination showed that the exposure condition dramatically affected the degradation process of coatings. Flowing immersion resulted in much greater corrosion damage to the coatings than that of the static condition. The effect of flow on the degradation of the coating seems to involve ion rather than water diffusion in the coating and it confirms that the flowing test can be a novel means for examination of the protective performance of a coating. Article entitled “Comparison of the Degradation Behaviour of Fusion Bonded
AUGUST 2006
ON
POWDER
Epoxy Powder Coating Systems under Flowing and Static Conditions” by Y H Wei and associates at the State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China, published in Corrosion Science, Jun 2006, 48 (6), 14491461
C O AT I N G S be expanded to reach up to 5000 tonnes/y at a later time. Buoyant sales of white goods and auto ancillaries is bolstering the powder coatings segment, which has a growth rate of 20%/y. European Paint and Resin News, Jun 2006, 44 (6), 11
INDUSTRY NEWS Acriton and Barpol sold to Industrias Titan Barpimo has sold two of its business units, Acriton and Barpol, to its national competitor, Spanish paint maker Industrias Titan. Acriton, produces architectural coatings, and Barpol, is a powder coatings maker. They posted a combined turnover of €13 M in 2005. European Paint and Resin News, Jun 2006, 44 (6), 4
Asian Paints gains from India’s construction boom Asian Paints’ sales grew 17.4% for the fiscal year ended 31 Mar 2006 on the back of a construction boom in India. Net sales for the year increased to Rup 30.2 bn (€522.08 M) as profit before tax and after goodwill rose by 19.2% to Rup 3.43 bn from Rup 2.878 bn the previous year. The company’s industrial business grew over 20% because of improved sales in automotive coatings, powder coatings and protective coatings. International paint sales grew 15.7% to Rup 5.3 bn. European Paint and Resin News, Jun 2006, 44 (6), 7-8
Asian Paints builds new powder coat factory in Baddi, India Asian Paints is setting up a new powder coatings factory at Baddi in Himachal Pradesh, India. The new plant will have an initial capacity of 1200 tonnes/y but will
Jotun has paint plans Norway based coatings manufacturer Jotun will build two powder coating and paint production plants in Pune, India, under a NKR 120 M (€15.1 M) investment. Construction of the factories will begin in 2007. The new powder coating and paint factories are scheduled to be on stream by 2Q 2008. ICIS Chemical Business, 10 Jul 2006, (Website: http://icischemicalbusiness.com)
Rohm and Haas 2Q 2006 results Rohm and Haas Co reported 2Q ending Jun 2006 sales of $2081 M (+5% over 2Q 2005) driven primarily by higher demand. For 2Q 2006, earnings from continuing operations were $192 M (earnings of $172 M in 2Q 2005). For 2Q 2006, sales in the Coatings segment were $739 M an increase of 4% over 2Q 2005. Architectural and Functional Coatings sales increased 4% for 2Q 2006. Powder Coatings sales were flat at $85 M for 2Q 2006. Monomer sales were $499 M during 2Q 2006 (+1% over $495 M in 2Q 2005). Sales of downstream Rohm and Haas speciality businesses were 8% higher during 2Q 2006. The Performance Chemicals sales were $452 M (+6% over 2Q 2005). Sales in Plastics Additives were up 9% for 2Q 2006 while, Consumer and Industrial Specialties sales increased 2%. Sales of Process Chemicals for 2Q 2006 were up 4%. For 2Q 2006, Electronic Materials recorded sales of $393 M (+21% over 2Q 2005). Semiconductor Technologies sales increased 5