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The challenge of powder waste reduction
F O C U S shown in the cure kinetics obtained in the isothermal mode, it was apparent that the mixtures were not fully cured at this temperature. It seems that high temperatures are required to completely cure the mixtures. Apparently, while the cure temperature may have a significant influence on the mechanical and chemical properties, it has only a slight effect on the gloss reduction of powder coating systems, suggesting that the gloss levels of the powder coatings might be already reached at a certain degree of conversion. The polyester resin does not influence the gloss levels but only affects the macroscopic appearance such as levelling and smoothness. In the full matt system the surface structure becomes larger and tougher with addition of the polyester but the gloss level remains constant. This implies that the second interval between the later two reaction steps can be ignored in the gloss reduction. In order to understand the role of both components, other formulations were evaluated. When the acrylic resin was replaced by a highly reactive carboxyl-terminated polyester resin with acid value in the range of 90-100 in the fully formulated systems, a large gloss reduction was not observed but merely coarse surface structures with irregular large particles spread on the surface of the coating. This indicates that the difference in reactivity is not important in obtaining low gloss coatings, and the heterogeneity of the two-phase morphology is required. The addition of a wide range of other curing agents did not induce a gloss reduction at low temperatures. The effectiveness of the two curing agents, which were discussed earlier, suggests that the reactivity and compatibility must be balanced to give a desirable low gloss level. This experimental work sets the ideal concept that the optimization of reactivity and 4
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compatibility may control the gloss level at low curing temperatures. If low gloss is a consequence of morphology development in powder coatings, then it is known that morphological properties such as the shape and size of immiscible droplets are affected by the processing conditions. The gloss level of the fully formulated powder coating system was examined using different processing conditions in the twin-screw extruder. Results showed that gloss level, particularly the 85° gloss, increases with increasing process temperature. This suggests that the acrylic resin might be more miscible with the epoxy and polyester resins at the higher processing temperatures leading to decreasing the size and concentration of the immiscible droplets. The effect of the feeding rate is ambiguous and cannot be clearly explained. Torque increases with increased feed rate and the immiscible acrylic and primary resins are mixed under a high shear stress. It could be supposed that this condition lowers the size of the immiscible droplets and gives a more fine surface structure. However, the results are contrary to this expectation. The influence of the feeding rate is not observed at the low processing temperature and the high feeding rate gives a more rough surface structure at the higher temperature. It has proved difficult to correlate the combined effect of high temperature and feeding rate of a twin-screw extruder on the formation of surface structures of powder coating and further investigation is required. Nevertheless, it should be concluded that the processing conditions strongly affect the gloss reduction. Article entitled “Gloss Reduction in Low Temperature Curable Hybrid Powder Coatings” by Sang Sun Lee, et al of the powder coating team, Central Research Institute, Kumgang Korea Chemical Co Ltd, published in Progress in Organic Coatings 46 (2003) 266-272, an Elsevier publication
C OAT I N G S The challenge of powder waste reduction A paper by Mike Cowley and Malcolm Griffiths of Ad-Qual Group describes the growth of powder coatings since its humble beginning some fifty years ago. In comparison with the alternative industrial coatings technologies they are emphatic in their belief that powder coating, in the present day global market, must offer the best route industrially to adopting an environmentally friendly process. The industry is largely held to blame for the failure to capitalize on the early promise offered by a 100% nonvolatile powder coating process. The most environmentally damaging aspect of powder coating is the amount of powder that is wasted. An efficient one or two colour manual or automated system can recycle oversprayed powder and minimize waste, but commercially, with a need for multi-colour systems, it is often cheaper to spray to waste. In many of these installations, huge quantities of powder coating are sprayed once, lost into the recovery system, mixed with all the other oversprayed materials, and then packaged for disposal. The initial dream for powder coating was that it could be recycled and re-used, making it competitive with liquid coating systems on a cost basis. Many years ago, when OPEC was formed, users realized that 50% of the content of paint just evaporated into the air, and only 50% of the purchase was usable. This realization prompted the development of application equipment that markedly improved the transfer efficiency of paints. The same focus should be applied to powder coating. Applicators should not waste, in many instances, more than 50% of their coating powder. It is the authors’ opinion that material suppliers, equipment manufacturers and key personnel have a major role in influencing this market place and to providing SEPTEMBER 2003
F O C US the tools to combat this discarded asset. Education is required to highlight the correct use of different materials, various processes and informed selection to meet end user requirements. At the same time, waste minimization should be a goal for all, particularly as, as time goes on, it will be increasingly expensive to dispose of this powder. Manufacturers have a role to play, even if it means some reduction in sales, through technological advances to improve transfer efficiency, which would result in justifiable higher prices. Equipment suppliers have to sell the benefits of improved efficiency, more innovative colour change schemes but at an improved cost/benefit. Applicators, through their trade associations, should request a deeper understanding of the process. There is no doubt that a trained and motivated applicator, using electrostatic spray methods can save money by improving quality, higher productivity but most importantly saving powder. Action is also required from the knowledgeable sector of the industry to provide the tools to give useful information a better understanding, and more detailed explanations concerning all aspects of powder coating. Article entitled “A Waste of 50 Years” by Mike Cowley and Malcolm Griffiths of the Ad-Qual Group, published in European Powder Coatings – Handbook and Directory 2004, Jul 2003, 6, 8, a publication from the Polymers Paint, and Colour Journal
INDUSTRY NEWS UCB: exchange rate variances negatively affect group current result The UCB group achieved a consolidated turnover for the first six months of 2003 of €1,512 million, including the positive impact of the acquisition of SEPTEMBER 2003
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Solutia and the negative impact of exchange rates. This results in an increase of 14%, compared to the same period last year. UCB confirmed a stability of current profit at constant exchange rates compared to the record year 2002. Net profit after tax reduced by 25 %, influenced by exceptional provisions for restructuring of Surface Specialties which increased its turnover by 42% to €773 million. The turnover of the acquired Solutia activities amounted to €262 million. Coatings Flash, 18 Aug 2003. Website: http://www.coatings.de
Bayer Polymers plans large-scale investments at its Caojing, China, site Bayer Polymers, a division of Bayer AG, plans to expand its Caojing site near Shanghai, China, making it Bayer Polymers’ most important production facility for coating raw materials in the Asia Pacific region. Production plants for aliphatic and aromatic polyisocyanates as well as the monomer hexamethylene diisocyanate (HDI) will be constructed in three phases at the Shanghai Chemical Industry Park. This project is being managed by Bayer Coatings Systems Shanghai Company Limited (BCSS), a wholly-owned Bayer subsidiary that develops, produces and markets raw materials for coatings and adhesives and also provides associated technical services. Coatings Flash, 18 Aug 2003. Website: http://www.coatings.de
Jotun group down in interim 2003 sales and profits The Jotun group disclosed that sales fell to NOK 1.795 bn in 1Q 2003 from NOK 2.008 bn in 1Q 2002. Pre-tax profits on ordinary activities fell to NOK 185 M from NOK 247 M. The firm stopped powder coatings production in the
C OAT I N G S UK and relocated to Norway and the Czech Republic. The UK operation will be turned into a sales unit. The firm is presently building a powder coatings facility in Pakistan and another in Vietnam. European Paint and Resin News, Jul 2003, 41 (7), 7
OZPK launches powder coating production in Russia OZPK of St Petersburg, Russia, will start producing powder coatings in Russia. The firm is claimed to have installed brand new production machinery. European Paint and Resin News, Jul 2003, 41 (7), 9
Dow starts up epoxy plant in China Dow Chemical has put on stream a 41,000 tonne epoxy resin production facility in Zhanguagang, China. The facility produces solid epoxy resins intended for powder coatings and liquid paint applications. It also produces brominated epoxy resins for electrical laminates. The facility will supply the Australasian, Asian and Chinese markets. Dow already has a 30,000 tonne epoxy production facility in Kumi, Korea, and a 40,000 tonne facility in Kinu Ura, Japan. European Paint and Resin News, Jul 2003, 41 (7), 10
Eastman announces steps to improve profitability Eastman Chemical Company announced steps to improve profitability by addressing underperforming businesses and product lines in one of its major segments. Eastman identified the businesses and product lines in its coatings, adhesives, specialty polymers and inks segment (CASPI) “that are performing below acceptable financial levels in their current structure and 5
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POWDER
compatibility may control the gloss level at low curing temperatures. If low gloss is a consequence of morphology development in powder coatings, then it is known that morphological properties such as the shape and size of immiscible droplets are affected by the processing conditions. The gloss level of the fully formulated powder coating system was examined using different processing conditions in the twin-screw extruder. Results showed that gloss level, particularly the 85° gloss, increases with increasing process temperature. This suggests that the acrylic resin might be more miscible with the epoxy and polyester resins at the higher processing temperatures leading to decreasing the size and concentration of the immiscible droplets. The effect of the feeding rate is ambiguous and cannot be clearly explained. Torque increases with increased feed rate and the immiscible acrylic and primary resins are mixed under a high shear stress. It could be supposed that this condition lowers the size of the immiscible droplets and gives a more fine surface structure. However, the results are contrary to this expectation. The influence of the feeding rate is not observed at the low processing temperature and the high feeding rate gives a more rough surface structure at the higher temperature. It has proved difficult to correlate the combined effect of high temperature and feeding rate of a twin-screw extruder on the formation of surface structures of powder coating and further investigation is required. Nevertheless, it should be concluded that the processing conditions strongly affect the gloss reduction. Article entitled “Gloss Reduction in Low Temperature Curable Hybrid Powder Coatings” by Sang Sun Lee, et al of the powder coating team, Central Research Institute, Kumgang Korea Chemical Co Ltd, published in Progress in Organic Coatings 46 (2003) 266-272, an Elsevier publication
C OAT I N G S The challenge of powder waste reduction A paper by Mike Cowley and Malcolm Griffiths of Ad-Qual Group describes the growth of powder coatings since its humble beginning some fifty years ago. In comparison with the alternative industrial coatings technologies they are emphatic in their belief that powder coating, in the present day global market, must offer the best route industrially to adopting an environmentally friendly process. The industry is largely held to blame for the failure to capitalize on the early promise offered by a 100% nonvolatile powder coating process. The most environmentally damaging aspect of powder coating is the amount of powder that is wasted. An efficient one or two colour manual or automated system can recycle oversprayed powder and minimize waste, but commercially, with a need for multi-colour systems, it is often cheaper to spray to waste. In many of these installations, huge quantities of powder coating are sprayed once, lost into the recovery system, mixed with all the other oversprayed materials, and then packaged for disposal. The initial dream for powder coating was that it could be recycled and re-used, making it competitive with liquid coating systems on a cost basis. Many years ago, when OPEC was formed, users realized that 50% of the content of paint just evaporated into the air, and only 50% of the purchase was usable. This realization prompted the development of application equipment that markedly improved the transfer efficiency of paints. The same focus should be applied to powder coating. Applicators should not waste, in many instances, more than 50% of their coating powder. It is the authors’ opinion that material suppliers, equipment manufacturers and key personnel have a major role in influencing this market place and to providing SEPTEMBER 2003
F O C US the tools to combat this discarded asset. Education is required to highlight the correct use of different materials, various processes and informed selection to meet end user requirements. At the same time, waste minimization should be a goal for all, particularly as, as time goes on, it will be increasingly expensive to dispose of this powder. Manufacturers have a role to play, even if it means some reduction in sales, through technological advances to improve transfer efficiency, which would result in justifiable higher prices. Equipment suppliers have to sell the benefits of improved efficiency, more innovative colour change schemes but at an improved cost/benefit. Applicators, through their trade associations, should request a deeper understanding of the process. There is no doubt that a trained and motivated applicator, using electrostatic spray methods can save money by improving quality, higher productivity but most importantly saving powder. Action is also required from the knowledgeable sector of the industry to provide the tools to give useful information a better understanding, and more detailed explanations concerning all aspects of powder coating. Article entitled “A Waste of 50 Years” by Mike Cowley and Malcolm Griffiths of the Ad-Qual Group, published in European Powder Coatings – Handbook and Directory 2004, Jul 2003, 6, 8, a publication from the Polymers Paint, and Colour Journal
INDUSTRY NEWS UCB: exchange rate variances negatively affect group current result The UCB group achieved a consolidated turnover for the first six months of 2003 of €1,512 million, including the positive impact of the acquisition of SEPTEMBER 2003
O N
POWDER
Solutia and the negative impact of exchange rates. This results in an increase of 14%, compared to the same period last year. UCB confirmed a stability of current profit at constant exchange rates compared to the record year 2002. Net profit after tax reduced by 25 %, influenced by exceptional provisions for restructuring of Surface Specialties which increased its turnover by 42% to €773 million. The turnover of the acquired Solutia activities amounted to €262 million. Coatings Flash, 18 Aug 2003. Website: http://www.coatings.de
Bayer Polymers plans large-scale investments at its Caojing, China, site Bayer Polymers, a division of Bayer AG, plans to expand its Caojing site near Shanghai, China, making it Bayer Polymers’ most important production facility for coating raw materials in the Asia Pacific region. Production plants for aliphatic and aromatic polyisocyanates as well as the monomer hexamethylene diisocyanate (HDI) will be constructed in three phases at the Shanghai Chemical Industry Park. This project is being managed by Bayer Coatings Systems Shanghai Company Limited (BCSS), a wholly-owned Bayer subsidiary that develops, produces and markets raw materials for coatings and adhesives and also provides associated technical services. Coatings Flash, 18 Aug 2003. Website: http://www.coatings.de
Jotun group down in interim 2003 sales and profits The Jotun group disclosed that sales fell to NOK 1.795 bn in 1Q 2003 from NOK 2.008 bn in 1Q 2002. Pre-tax profits on ordinary activities fell to NOK 185 M from NOK 247 M. The firm stopped powder coatings production in the
C OAT I N G S UK and relocated to Norway and the Czech Republic. The UK operation will be turned into a sales unit. The firm is presently building a powder coatings facility in Pakistan and another in Vietnam. European Paint and Resin News, Jul 2003, 41 (7), 7
OZPK launches powder coating production in Russia OZPK of St Petersburg, Russia, will start producing powder coatings in Russia. The firm is claimed to have installed brand new production machinery. European Paint and Resin News, Jul 2003, 41 (7), 9
Dow starts up epoxy plant in China Dow Chemical has put on stream a 41,000 tonne epoxy resin production facility in Zhanguagang, China. The facility produces solid epoxy resins intended for powder coatings and liquid paint applications. It also produces brominated epoxy resins for electrical laminates. The facility will supply the Australasian, Asian and Chinese markets. Dow already has a 30,000 tonne epoxy production facility in Kumi, Korea, and a 40,000 tonne facility in Kinu Ura, Japan. European Paint and Resin News, Jul 2003, 41 (7), 10
Eastman announces steps to improve profitability Eastman Chemical Company announced steps to improve profitability by addressing underperforming businesses and product lines in one of its major segments. Eastman identified the businesses and product lines in its coatings, adhesives, specialty polymers and inks segment (CASPI) “that are performing below acceptable financial levels in their current structure and 5