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Finishing touch
[
] , { a ! , ][*ll ~ I, I~-], I I,
~J~!;:i~;: ~r. . . . . . .
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Finishing Touch The latest powder coatings combine function and fashion to offer end users the best of both worlds. By Eugenio Gomez, European Segment Manager, Architectural and Industrial Products, Rohm and Haas Powder Coatings, Castellon, Spain
s architects and designers look for more varied and exciting finishes, they are realizing the benefits that powder coatings can provide them with as a high-performance, environmentally responsible method of enhancing the b e a u t y and durability of the buildings they design. In particular, the choice offered for coating aluminum profiles and cladding grows with new innovations in application and finishes, including decorative marbled and wood effects, providing architects and designers with quality powder coatings technology and unique finishes to differentiate and protect their designs. Rohm and H a a s Powder Coatings' architectural products have been designed over m a n y years to satisfy the unique requirements of the worldwide building products industry with all the environmental excellence of the powder coating process. Available to architects and applicators globally, the broad range of products in the architectural portfolio, designed to balance economics and performance, exhibit a range of outdoor w e a t h e r a b i l i t y and mechanical properties that can allow a user to meet the various demands of architectural governing bodies. These include the American Architectural M a n u f a c t u r e r s Association (AAMA) specifications for organic coatings on aluminum extrusions and panels as well as the strict quality requirements of E u r o p e a n architectural governing bodies - GSB, QUALICOAT (class 1 and 2) and British Standard (BS 6496 and EN12206-1).
A
WOOD
EFFECT
FINISHING
Wood effect finishing has seen growth in popularity over the years, particularly in Europe, as a real a l t e r native to typical architectural materials such as wood, marble and granite The powder coated finish provides the high weathering performance of aluminum c o u pled with the decorative appearance of real w o o d Decorative wood effects can be achieved in one of three ways: Sublichromy, Naturall 1, and Effecta 2 SUB[.ICHROMY
Figure 1:Wrapping the profile with a film bag.
PROCESS
This process produces a wood effect p a t t e r n onto December 2005
aluminum profiles using a transferable media coated with special inks in a three-step process. When placed under a significant combination of heat and low pressure, the pattern is transferred onto a surface that has been previously coated with a specifically formulated powder coating. The procedure for Sublichromy is substrate pretreatment, basecoat powder application, and sublimation process. S u b s t r a t e p r e t r e a t m e n t : The p r e t r e a t m e n t process is key to ensure that the initial powder coatings layer achieves good adhesion to the surface and exhibits good corrosion resistance. P r e t r e a t m e n t s can include current hexavalent chrome systems and more e n v i r o n m e n t a l l y friendly trivalent and chrome-free methods. B a s e c o a t p o w d e r a p p l i c a t i o n : A Qualicoatapproved polyurethane or polyester TGIC or TGICfree powder coating is applied to a coating thickness of up to 60 pm and then cured at 180 ° to 200°C for approximately 20 minutes. This provides the base cost for the transfer of the ink design onto the surface in the next stage. S u b l i m a t i o n : The coated a l u m i n u m profile is
Figure 2: Aluminum bars wrapped with film bags.
37
Figure 3: Making contact with vacuum devices.
Figure 4: A l u m i n u m bars going into the oven at 200°C.
base coat. S u b l i m a t i o n - - o r ink t r a n s f e r - - o c c u r s in the oven again at 150 ° to 160°C after which the bag is removed a n d the profile is allowed to cool. (See Figures 1 to 4.) Qualicoat specifications for decorative finishes are equivFigure 5: Visual inspection of a coated glass panel. alent to those for s t a n d a r d On the left side, the decorative effect is different coatings finishes with the only than the right-hand side due to incorrect transfer difference being the color deviprocess parameters. The standard process was followed on the right side. ations. Since decorative effects don't have a uniform appearThe reverse of the above panel demonstrates ance, and the colors of the base how the incorrect transfer parameters affect ink powder coat and ink transfer penetration in the basecoat. top coat can change each other in different ways, the Light Figure 6: Visual inspection of a coated glass panel. Fastness test was introduced. wrapped in the bag t h a t has the transfer ink coated This test evaluates the color deviation and gloss on one side and sealed at one end and along the top. reduction at the same time to produce a Qualicoat A vacuum is applied to the open end of the bag and measurement for the specification of the finish. the transfer ink comes into contact with the powder Another way to characterize the quality of the film of increasing thickness has been applied rom right to left with a Rohm and Haas baseoat on a glass panel; the decorative effect has een transferred according to the manufacturr's specifications. This photo depicts the reverse of the aboveapplied film where a 100% penetration of the ink is obtained for a thickness of 100 pm and above.
ii
HotDip Strippable Plating Mask Kit Clean, sharp, distinct stop off ilnes. Klt wlth I quart pot and 5 Ibs. of Therrno Cote N-4 strippable coating. Cools fast to give you perfect mask. Non-Contarnmat=ng. Peel off and rernelt for reuse. Write for details and
12 Cork Hill Road • RO. Box 365 • Franklin, NJ 07416 Tel: 973-209-6210 • Fax: 973-209-6435
Circle 027 on reader information card or go to www.metalfinishing.com/advertisers 38
Circle 038on readerinformationcardor go to www.metalfinishing.com/advertisers www.metalfinishing.com
Second
First
processed on different application and transfer plants. • Basecoats t h a t are the s a m e color, but formulated with powder of different chemical composition, will have a similar w e a t h e r i n g performance, b u t m a y have a different solvent resistance.
La~
Layer
Chromate
Aluminum
Figure 7: P a t t e r n e d section layer of powder paint.
process is to verify the degree of ink p e n e t r a t i o n in the powdercoated base layer. This test can be performed using a metallographic microscope and inspecting the cross-section of a coated profile. This method m a k e s it possible to monitor how much ink has p e n e t r a t e d into and through the base powder coating--better penetration improves the final performance of the coated product. The ink p e n e t r a t i o n through the base coat can also be visually inspected by coating glass plates and inspecting the reverse side of the plates to d e t e r m i n e the p e n e t r a t i o n of the t r a n s f e r ink through the base coat. (See Figures 5 and 6.)
Troubleshooting Sublichromy: In order to achieve a high-quality decorative finish using sublichromy, the following processing considerations m u s t be taken into account: • Base powder coatings suitable for sublichromy have a typically a low hiding power. To avoid any inconsistency in the finished surface, a chromium phosphate treated aluminum should not d e m o n s t r a t e any "conversion marks." • The coating film thickness should be even (optimum b e t w e e n 80 and 100 pm). A variable thickness could give rise to inconsistent finishes because of the different hiding effect of the basecoat; even the
decorative effect could change due to the uneven distribution of the transferred ink through the film. • The curing parameters of the basecoat (times and temperatures) indicated by the powder manufacturer should be strictly adhered to, so you avoid any changes in the gloss level during a production run. Stops for a shift change or break should be avoided or carefully monitored. • The transfer process must be performed according to the parameters (temperatures, times, pressures) indicated by the transferable support manufacturer. Too long t r a n s f e r times could prevent the detaching of the transferable support after the process. Uneven temp e r a t u r e s and t r a n s f e r pressures could cause halos of the decorative effect. • Basecoat supports waiting for the transfer process should be k e p t in clean and dry conditions or the risk of d u s t or moisture deposition on the surface increases. • Re-coating of a l u m i n u m profiles t h a t have a l r e a d y been t h r o u g h the t r a n s f e r process should be carefully e v a l u a t e d since the transferred ink could "sublimate" through the new film. • Some powder basecoats and decorative effects may give rise to different finishes if
NATURALL P R O C I S S The N a t u r a l l process is also known as the "powder- on-pow-
Circle 023 on reader informationcardor go to
www.metalfinishing.com/advertisers
D e c e m b e r 2005
39
der coating system" as it is a five-stage process using two applications of powder coatings. This patented process to obtain a wood effect finishing on a l u m i n u m profiles can be achieved by using Qualicoat-approved, TGIC-free polyester powders: • Substrate pretreatment; • first layer powder base coat application (60 to 80 pm); • melting process at 100 ° to 120°C; • second layer powder application--a flash coating of less t h a n 10 p m t h r o u g h a p a t t e r n e d silkscreen; • and curing process (180 ° to 200°C for 20 minutes). After the final curing process, the patterned second layer of powder paint has penetrated into the first one, creating a compact and uniform layer of at least 60 pm thick. The final result is a powder-onpowder process and the surface appears similar to wood in look and feel with high performance outdoor weatherability characteristics. (See Figure 7.) The most important advantage of the Naturall system over the sublichromy system is the absence of ink. Powder-on-powder processes offer a consistent coating of like chemistries w h e r e a s during the
Sublichromy process the ink layer is a different chemistry than the base coat, which has different performance characteristics. A l u m i n u m profiles coated using the N a t u r a l l process can only be approved with powders t h a t have been Qualicoat approved and provide the associated performance characteristics for external weatherability. |FF|clrA
PRO©|S$
The Effecta process is a patented process to obtain a wood effect finishing on aluminum profiles using a specially designed roller application technique with Qualicoat approved powders: • Substrate pretreatment; • first powder coatings application (60 to 80 pm); • melting process at 100 ° to 120°C, • second powder coatings application; • decorative dffect a p p l i c a t i o n - - u s i n g a special roller; • melting process at 100 ° to 120°C; • third powder coatings application (if desired); • decorative effect application using a special roller (if desired); • and curing process (180 ° to 200°C for 35 minutes using vertica curing lines). After the curing process, the High Efficiency- System is 60% more efficient in most cases. second layer and/or third of Lower Utility Bills- Gas firing saves 8oo% over electric in some areas. powder coating penetrates into the first one, creating a comLower Initial Equipment Cost - 25% less than steam. pact and uniform layer at least Lower Operating Cost - Reduced labor because there are no steam 60 pm thick. And similar to the trap discharges, feed water makeup, water softening, blow-off or water N a t u r a l l process, the final treatment. In many areas boiler inspections and attendance are not required. result is an aluminum profile Longer Equipment Life- Many systems in operation for over 35 years. surface that has a similar look and feel as wood but with outstanding w e a t h e r a b i l i t y and SUPPLY EXPANSION TANK1 , COMPRESSED AIRORNITROGEN HOTWATEB'Lt q .qH~_EiE;ItJL :~),l INACCESSIBLE LOCATION outdoor performance characterHOTWATER~-~ ~ ....... ~J~" . . . . . . . . rT..r. | I RE]]JBN ~[ ~ :: ".u.a,,, .t,tuurr ~ ~ . ~ / . _ T L E I istics. As with the Naturall ;: technology, the most important AIBL j v , :,': :: ; :L.,~:]~ ~ 115V60Hzlph SEPARATOR "-., PUMP E~iZ==-GASINLET technical advantage (there are , ;- - . :,,: other process and cost advantages) of the Effecta system A leader for over half a century, Parker Boiler has been versus the sublichromy system upgrading customers to efficient medium and high is the absence of ink in the temperature closed loop hot water heating systems from transfer process.
Parker Closed Loop Hot Water System Saves Big Money
"WA'ER"A'EUP ,NL. I
their old direct firing, electric emersion and low and high pressure steam boilers. One of the few boiler manufacturers who can trim a hot water system over Section IV 250°F limitations, Parker Boiler designs and manufactures entire systems including boilers, air separators, expansion tanks, pumps, coils, and temperature controllers for up to 400° service. Our network of representatives sell, support and service our customers nationwide.
t
,T
PARKER BOILER CO. 5930 Bandini Boulevard Los Angeles, CA 90040 Tel (323) 727-9800 Fax (323) 722-2848 www.parkerboiler.com
For more information, contact Eugenio Gomez at (e-maiD eugeniogomez@rohmhaas, com.
mf
Circle 028 on reader information card or go to www.metalfinishing.com/advertisers
40
www.metalfinishing.com
] , { a ! , ][*ll ~ I, I~-], I I,
~J~!;:i~;: ~r. . . . . . .
r
Finishing Touch The latest powder coatings combine function and fashion to offer end users the best of both worlds. By Eugenio Gomez, European Segment Manager, Architectural and Industrial Products, Rohm and Haas Powder Coatings, Castellon, Spain
s architects and designers look for more varied and exciting finishes, they are realizing the benefits that powder coatings can provide them with as a high-performance, environmentally responsible method of enhancing the b e a u t y and durability of the buildings they design. In particular, the choice offered for coating aluminum profiles and cladding grows with new innovations in application and finishes, including decorative marbled and wood effects, providing architects and designers with quality powder coatings technology and unique finishes to differentiate and protect their designs. Rohm and H a a s Powder Coatings' architectural products have been designed over m a n y years to satisfy the unique requirements of the worldwide building products industry with all the environmental excellence of the powder coating process. Available to architects and applicators globally, the broad range of products in the architectural portfolio, designed to balance economics and performance, exhibit a range of outdoor w e a t h e r a b i l i t y and mechanical properties that can allow a user to meet the various demands of architectural governing bodies. These include the American Architectural M a n u f a c t u r e r s Association (AAMA) specifications for organic coatings on aluminum extrusions and panels as well as the strict quality requirements of E u r o p e a n architectural governing bodies - GSB, QUALICOAT (class 1 and 2) and British Standard (BS 6496 and EN12206-1).
A
WOOD
EFFECT
FINISHING
Wood effect finishing has seen growth in popularity over the years, particularly in Europe, as a real a l t e r native to typical architectural materials such as wood, marble and granite The powder coated finish provides the high weathering performance of aluminum c o u pled with the decorative appearance of real w o o d Decorative wood effects can be achieved in one of three ways: Sublichromy, Naturall 1, and Effecta 2 SUB[.ICHROMY
Figure 1:Wrapping the profile with a film bag.
PROCESS
This process produces a wood effect p a t t e r n onto December 2005
aluminum profiles using a transferable media coated with special inks in a three-step process. When placed under a significant combination of heat and low pressure, the pattern is transferred onto a surface that has been previously coated with a specifically formulated powder coating. The procedure for Sublichromy is substrate pretreatment, basecoat powder application, and sublimation process. S u b s t r a t e p r e t r e a t m e n t : The p r e t r e a t m e n t process is key to ensure that the initial powder coatings layer achieves good adhesion to the surface and exhibits good corrosion resistance. P r e t r e a t m e n t s can include current hexavalent chrome systems and more e n v i r o n m e n t a l l y friendly trivalent and chrome-free methods. B a s e c o a t p o w d e r a p p l i c a t i o n : A Qualicoatapproved polyurethane or polyester TGIC or TGICfree powder coating is applied to a coating thickness of up to 60 pm and then cured at 180 ° to 200°C for approximately 20 minutes. This provides the base cost for the transfer of the ink design onto the surface in the next stage. S u b l i m a t i o n : The coated a l u m i n u m profile is
Figure 2: Aluminum bars wrapped with film bags.
37
Figure 3: Making contact with vacuum devices.
Figure 4: A l u m i n u m bars going into the oven at 200°C.
base coat. S u b l i m a t i o n - - o r ink t r a n s f e r - - o c c u r s in the oven again at 150 ° to 160°C after which the bag is removed a n d the profile is allowed to cool. (See Figures 1 to 4.) Qualicoat specifications for decorative finishes are equivFigure 5: Visual inspection of a coated glass panel. alent to those for s t a n d a r d On the left side, the decorative effect is different coatings finishes with the only than the right-hand side due to incorrect transfer difference being the color deviprocess parameters. The standard process was followed on the right side. ations. Since decorative effects don't have a uniform appearThe reverse of the above panel demonstrates ance, and the colors of the base how the incorrect transfer parameters affect ink powder coat and ink transfer penetration in the basecoat. top coat can change each other in different ways, the Light Figure 6: Visual inspection of a coated glass panel. Fastness test was introduced. wrapped in the bag t h a t has the transfer ink coated This test evaluates the color deviation and gloss on one side and sealed at one end and along the top. reduction at the same time to produce a Qualicoat A vacuum is applied to the open end of the bag and measurement for the specification of the finish. the transfer ink comes into contact with the powder Another way to characterize the quality of the film of increasing thickness has been applied rom right to left with a Rohm and Haas baseoat on a glass panel; the decorative effect has een transferred according to the manufacturr's specifications. This photo depicts the reverse of the aboveapplied film where a 100% penetration of the ink is obtained for a thickness of 100 pm and above.
ii
HotDip Strippable Plating Mask Kit Clean, sharp, distinct stop off ilnes. Klt wlth I quart pot and 5 Ibs. of Therrno Cote N-4 strippable coating. Cools fast to give you perfect mask. Non-Contarnmat=ng. Peel off and rernelt for reuse. Write for details and
12 Cork Hill Road • RO. Box 365 • Franklin, NJ 07416 Tel: 973-209-6210 • Fax: 973-209-6435
Circle 027 on reader information card or go to www.metalfinishing.com/advertisers 38
Circle 038on readerinformationcardor go to www.metalfinishing.com/advertisers www.metalfinishing.com
Second
First
processed on different application and transfer plants. • Basecoats t h a t are the s a m e color, but formulated with powder of different chemical composition, will have a similar w e a t h e r i n g performance, b u t m a y have a different solvent resistance.
La~
Layer
Chromate
Aluminum
Figure 7: P a t t e r n e d section layer of powder paint.
process is to verify the degree of ink p e n e t r a t i o n in the powdercoated base layer. This test can be performed using a metallographic microscope and inspecting the cross-section of a coated profile. This method m a k e s it possible to monitor how much ink has p e n e t r a t e d into and through the base powder coating--better penetration improves the final performance of the coated product. The ink p e n e t r a t i o n through the base coat can also be visually inspected by coating glass plates and inspecting the reverse side of the plates to d e t e r m i n e the p e n e t r a t i o n of the t r a n s f e r ink through the base coat. (See Figures 5 and 6.)
Troubleshooting Sublichromy: In order to achieve a high-quality decorative finish using sublichromy, the following processing considerations m u s t be taken into account: • Base powder coatings suitable for sublichromy have a typically a low hiding power. To avoid any inconsistency in the finished surface, a chromium phosphate treated aluminum should not d e m o n s t r a t e any "conversion marks." • The coating film thickness should be even (optimum b e t w e e n 80 and 100 pm). A variable thickness could give rise to inconsistent finishes because of the different hiding effect of the basecoat; even the
decorative effect could change due to the uneven distribution of the transferred ink through the film. • The curing parameters of the basecoat (times and temperatures) indicated by the powder manufacturer should be strictly adhered to, so you avoid any changes in the gloss level during a production run. Stops for a shift change or break should be avoided or carefully monitored. • The transfer process must be performed according to the parameters (temperatures, times, pressures) indicated by the transferable support manufacturer. Too long t r a n s f e r times could prevent the detaching of the transferable support after the process. Uneven temp e r a t u r e s and t r a n s f e r pressures could cause halos of the decorative effect. • Basecoat supports waiting for the transfer process should be k e p t in clean and dry conditions or the risk of d u s t or moisture deposition on the surface increases. • Re-coating of a l u m i n u m profiles t h a t have a l r e a d y been t h r o u g h the t r a n s f e r process should be carefully e v a l u a t e d since the transferred ink could "sublimate" through the new film. • Some powder basecoats and decorative effects may give rise to different finishes if
NATURALL P R O C I S S The N a t u r a l l process is also known as the "powder- on-pow-
Circle 023 on reader informationcardor go to
www.metalfinishing.com/advertisers
D e c e m b e r 2005
39
der coating system" as it is a five-stage process using two applications of powder coatings. This patented process to obtain a wood effect finishing on a l u m i n u m profiles can be achieved by using Qualicoat-approved, TGIC-free polyester powders: • Substrate pretreatment; • first layer powder base coat application (60 to 80 pm); • melting process at 100 ° to 120°C; • second layer powder application--a flash coating of less t h a n 10 p m t h r o u g h a p a t t e r n e d silkscreen; • and curing process (180 ° to 200°C for 20 minutes). After the final curing process, the patterned second layer of powder paint has penetrated into the first one, creating a compact and uniform layer of at least 60 pm thick. The final result is a powder-onpowder process and the surface appears similar to wood in look and feel with high performance outdoor weatherability characteristics. (See Figure 7.) The most important advantage of the Naturall system over the sublichromy system is the absence of ink. Powder-on-powder processes offer a consistent coating of like chemistries w h e r e a s during the
Sublichromy process the ink layer is a different chemistry than the base coat, which has different performance characteristics. A l u m i n u m profiles coated using the N a t u r a l l process can only be approved with powders t h a t have been Qualicoat approved and provide the associated performance characteristics for external weatherability. |FF|clrA
PRO©|S$
The Effecta process is a patented process to obtain a wood effect finishing on aluminum profiles using a specially designed roller application technique with Qualicoat approved powders: • Substrate pretreatment; • first powder coatings application (60 to 80 pm); • melting process at 100 ° to 120°C, • second powder coatings application; • decorative dffect a p p l i c a t i o n - - u s i n g a special roller; • melting process at 100 ° to 120°C; • third powder coatings application (if desired); • decorative effect application using a special roller (if desired); • and curing process (180 ° to 200°C for 35 minutes using vertica curing lines). After the curing process, the High Efficiency- System is 60% more efficient in most cases. second layer and/or third of Lower Utility Bills- Gas firing saves 8oo% over electric in some areas. powder coating penetrates into the first one, creating a comLower Initial Equipment Cost - 25% less than steam. pact and uniform layer at least Lower Operating Cost - Reduced labor because there are no steam 60 pm thick. And similar to the trap discharges, feed water makeup, water softening, blow-off or water N a t u r a l l process, the final treatment. In many areas boiler inspections and attendance are not required. result is an aluminum profile Longer Equipment Life- Many systems in operation for over 35 years. surface that has a similar look and feel as wood but with outstanding w e a t h e r a b i l i t y and SUPPLY EXPANSION TANK1 , COMPRESSED AIRORNITROGEN HOTWATEB'Lt q .qH~_EiE;ItJL :~),l INACCESSIBLE LOCATION outdoor performance characterHOTWATER~-~ ~ ....... ~J~" . . . . . . . . rT..r. | I RE]]JBN ~[ ~ :: ".u.a,,, .t,tuurr ~ ~ . ~ / . _ T L E I istics. As with the Naturall ;: technology, the most important AIBL j v , :,': :: ; :L.,~:]~ ~ 115V60Hzlph SEPARATOR "-., PUMP E~iZ==-GASINLET technical advantage (there are , ;- - . :,,: other process and cost advantages) of the Effecta system A leader for over half a century, Parker Boiler has been versus the sublichromy system upgrading customers to efficient medium and high is the absence of ink in the temperature closed loop hot water heating systems from transfer process.
Parker Closed Loop Hot Water System Saves Big Money
"WA'ER"A'EUP ,NL. I
their old direct firing, electric emersion and low and high pressure steam boilers. One of the few boiler manufacturers who can trim a hot water system over Section IV 250°F limitations, Parker Boiler designs and manufactures entire systems including boilers, air separators, expansion tanks, pumps, coils, and temperature controllers for up to 400° service. Our network of representatives sell, support and service our customers nationwide.
t
,T
PARKER BOILER CO. 5930 Bandini Boulevard Los Angeles, CA 90040 Tel (323) 727-9800 Fax (323) 722-2848 www.parkerboiler.com
For more information, contact Eugenio Gomez at (e-maiD eugeniogomez@rohmhaas, com.
mf
Circle 028 on reader information card or go to www.metalfinishing.com/advertisers
40
www.metalfinishing.com