Web特集
September 10, 2008
Series: Focus on Paint Market in Japan
Features of industrial water-borne coating and spray
Cost saving and improvements of the workability are key objectives
High-solid coating for construction machinery is being approved
According to revised "air pollution control law", by 2010 total emission of VOC should be 30% less than 2000's. Therefore, major customers seriously respond.
Recent years, powder and water-borne coating have been applied; particularly for metal coating the shift to powder coating is very clear. Because of market recovery, environment-responsive paint is approved while investment or expansion of equipment is made. Major users try to improve global environmental in order to make corporate image better.
In industrial coating market, metal furniture makers make symbolic action. They approve powder coating in terms of formaldehyde-free and solution of indoor pollution issue, and recently consider dual spray line by power and water-borne coating. It means they plan to spray main colors by powder and small lots or many kinds of tailor-made colors by water-borne. Partition parts are design-oriented and need many colors; so water-borne paint is especially used because of easy toning metallic orientation. Major paint makers said, "Powder and water-borne coating are categorized as environment-responsive paint, but metal furniture manufacturers use both as the situation demands".
New coating for steel rack, launched this year, consists all of water-borne paints. Electrodeposition paint is applied for primer and water-borne for base coat. Anti-corrosion property is very considered. In addition, leading companies in industry try to apply water-borne coating, for example, automotive parts (shock absorber, interior parts) and industrial machinery. However, major paint players are disappointed because the movement of the shift to water-borne system is made among very limited users and no market expansion is made yet. There is a big gap between player's wish and market feedback."
Currently water-borne coating is categorized as two types. One is baking coat at 120-150 C. The other is air or force-drying coat used for automotive interior parts, industrial machinery and plastics products.
Major paints of baking coat is Alkyd, Acrylic, Polyester and Epoxy basis, the others are oxidative polymerization, melamine-isocyanate reactive type. Key paints by air, force-drying coat are high-solid, 2-component-water-borne basis.
Industrial coating depends on coated shape at customers and spray line conditions. Therefore, basic paint formulation could need tuning for each line. It seems customized one, major paint players noted.
It is impossible to manage emission control on water-borne paint same as solvent adjustment in solvent-borne coating in order to follow seasonal variations. Therefore, serious film defect and sagging happen due to temperature change. To solve the issue, pre-heat on coated material, high boiling point solvent and rheology control agent and suitable spray equipment for the line should be needed. End users, paint producers and equipment suppliers have to collaborate together in order to launch regular operation smoothly after line trial.
Although current water-borne coating shows same performance as solvent one, worse workability and cost increase makes disadvantage. Its application window is smaller and high cost of raw material in paint makes 1.5 - 2 times increase. Under current VOC regulation, end-users cannot get a merit only by environmental friendly.
As air or force-drying paint, 2-component water-borne urethane paint is demanded for top coat, but actually its pot life is very short and have an problem on the surface/appearance, so it is difficult to shift water-borne system quickly. As for construction machinery, high-solid coating is, in the meantime, applied to solve VOC issue.
Each thickness of industrial and construction machinery parts is varied, cast metal is sometimes used, and therefore, single coating formulation is not applicable. As required property depends on each part, one customer tries high-solid, the other use powder coating for possible part and apply air or force drying coating to thick or casting part.
In addition to VOC issue, CO2 emission is being also focused. Therefore, 2-component water-borne urethane paint will play an important role in the future. As this paint can make a coating under 100C by force-drying, customers gain not only environmental advantage but also cost merit.
Equipment producers are developing 2-componet mixers with good handling property and this equipment could be approved among industrial coating market. "Global warming is getting serious. Air-drying system could be ideal, but actually low temp baking system might make big advantage in terms of lower energy cost." market expert mentioned.
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