Comparison of Coating Techniques Gravure Roll (Contact) vs. Curtain (Non-contact)

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1 Comparison of Coating Techniques Gravure Roll (Contact) vs. Curtain (Non-contact) Presented by: Jens Vollpott Area Sales Manager KROENERT GmbH & Co KG Schützenstraße 105, D Hamburg, Page 1 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

2 Structure Introduction The Kroenert Group Coating Techniques Overview Gravure techniques, principle (contact) Curtain technique, principle (non contact) Coating Techniques - Limits Comparison gravure vs. curtain Conclusions Page 2 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

3 The KROENERT Group DRYTEC Norderstedt, GER KROENERT Hamburg, GER Bachofen + Meier Bülach, CH Page 3 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

4 Typical products Page 4 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

5 Coating Techniques - Overview UV-system Online Thickness Measurement Convective drying channel (18 m) steam moisturizer Auxiliary unwinding (wet laminating) Curtain- Coater Multi-Coater equipment with changeover Corona Web cleaner Unwinder Winder Online moisture measuring Laminate unwinding Auxiliary rewinding Lamination station WEKO moisturizer steam moisturizer Auxiliary unwinding (re-laminating) Page 5 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

6 Coating Techniques - Overview UV-system Online Thickness Measurement Convective drying channel (18 m) steam moisturizer Auxiliary unwinding (wet laminating) Curtain- Coater Multi-Coater equipment with changeover Corona Web cleaner Unwinder Winder Online moisture measuring Laminate unwinding Auxiliary rewinding Lamination station WEKO moisturizer steam moisturizer Auxiliary unwinding (re-laminating) Page 6 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

7 Coating Techniques - Overview UV-system Online Thickness Measurement Convective drying channel (18 m) steam moisturizer Auxiliary unwinding (wet laminating) Curtain- Coater Multi-Coater equipment with changeover Corona Web cleaner Unwinder Winder Online moisture measuring Laminate unwinding Auxiliary rewinding Lamination station WEKO moisturizer steam moisturizer Auxiliary unwinding (re-laminating) Page 7 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

8 Coating Techniques - Overview Self-metering systems Pre-metering systems Contact systems Non-contact systems Contact systems Non-contact systems 3 - rollers Metering nip Screen roller coating pan or open chamber Curtain Coating Slot die Slide die 4 - rollers Blade coating 5 - rollers Dip coating Screen roller coating closed and pressurized chamber Die coatings 6 - rollers Special solutions Die coatings Vaporize Plasma coating Spray coating Special solutions Scatter coating Powder coating Air knife Page 8 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

9 Gravure techniques, principle (contact) Conventional gravure T-type chamber Pressurized chamber MPG 600 CI With pan feeding and oscillating doctor blade in positive position. Direct and reverse coatings are possible Closed chamber system without pan, metering blade in negative position. Direct and reverse coatings are possible Closed chamber, pressure controlled without pan, metering blade in negative position (positive possible). Direct and reverse coatings are possible Large variability in coat weight with just one screen roller Page 9 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

10 Gravure techniques, principles (contact) Gravure Coating Pressurized Chamber MPG 600 Conventional gravure Page 10 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

11 Curtain technique, principle (non contact) 1-Layer Slot-Die 3-Layer Slide-Die Non-contact coating (no contact with the substrate web) High coating speeds No compound circulation and recirculation Contour coats with application weight tolerances of up to 1% Low wear, low maintenance (no rolls, blades, etc.) Short cleaning times Just one coating station for multiple functional coats (e.g. peelable labels, solvent-based varnish undercoats and top coats) Reduced raw material costs (e.g., multilayer structure, improved barrier properties due to multiple, but thinner layers) Greater range of application weights through opening and closing of slots Improved adhesion between layers More-compact coating systems lower investments (fewer coating stations and dryer sections) Page 11 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

12 Curtain technique, principle (non contact) 3-Layer Slide-Die Curtain Coating 1-Layer Slot-Die Page 12 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

13 Coating Techniques Limits by coat weight Coat Weight [gsm] 200 Standard Coating Systems Coat weight / Speed Metering nip (Comma) Screen rollers (Blade) Rollers 5-Rollers 6-Rollers 10 Curtain Die Speed [m/min] Page 13 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

14 Coating Techniques Limits by viscosity Viscosity [mpa s] Standard Coating Systems Viscosity / Speed Metering nip (Comma) Screen rollers (Blade) 5000 Rollers (4, 5 and 6) Curtain Die Speed [m/min] Page 14 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

15 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain max. working speed up to now: a) production machines b) R+D machines m/min m/min m/min m/min m/min m/min Min. working speed for stable operation < 20 m/min To be determined per product through test runs; experiences with acrylate adhesives 40 gsm wet app. 150 m/min 6 gsm wet app m/min Online Coat weight measurement unit Not necessary; only flow indicator is recommended. Not necessary; only a flow indicator is recommended. Page 15 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

16 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain Coat weight range (depending on coat weight and product) Viscosity (at shear rate >1.000 i/s) wet gsm wet gsm wet gsm mpas mpas Influence of unstable viscosity Compounds with intrinsic viscosity to be used, operation viscosity should be nearly constant The operation viscosity should not deviate more than ±30 % from the average viscosity Page 16 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

17 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain Surface tension Adaption of materials is possible < 30 mn/m dynamic Coat weight tolerances in lenght and cross profile ± 3% 1 3% for curtain die depending on required quality grade Contact / non contact coating to substrates Contact Non contact gentle operation for compounds and substrates Page 17 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

18 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain Compound circulation and recirculation Yes No, or only a small return of coating liquid Filtering of compounds Is recommended but not a requirement Without filtering there is a risk for streaks on the coated web and the curtain breaks down Influence of air into compounds Compounds should be bubble free Compounds have to be bubble free Page 18 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

19 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain Coat weight variance Variation without changing screen roller just by pump pressure adjustment Control of flow rate by pump pressure variance Web-width adjustment Change of sleeve type backing roller Manual or motorized adjustment of edge units Quality of rubber covered breaking roller Roundness tolerance of rubber backing roll 8 10 µm None Page 19 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

20 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain Influence of air boundary layer on substrates None Large, if speed exceeds 250 m/min; vacuum units are required Change time for exchange of compound With cleaning min; With second circulation system < 15 min With cleaning > 60 min; With second circulation system and if a new compound does not contaminate with the used slurry < 15 min Flexibility for small order lots Wide Limited Page 20 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

21 Comparison gravure vs. curtain MPG 600 Ci Multi Pressure Gravure 600 Chamber Injection SWC Single Wet Curtain Curtain Coating MWC Multi Wet Curtain Requirements for wear parts References (KROENERT group) Larger (sleeves, blades) 140 pieces in operation for different applications. Very less Actual development, app. 14 pieces supplied Price level differences for coating system including required auxiliary equipment 100 % 150 % >200 % Page 21 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

22 Conclusions Both coating systems gravure and curtain have their needs Both coating systems gravure and curtain have their limits Gravure system covers a wide range in coat weight and viscosity Curtain coating is limited in lower coat weights at lower speeds and in viscosity, but it is capable for higher speeds Curtain coating needs adaptation in surface tension of compound Curtain coating needs higher investment cost but less wear parts Curtain coating treat the materials much more gentle Curtain coating reduces raw material costs Gravure coating is preferable for short order runs Curtain coating is preferable for commodities and for multilayer functional coatings Page 22 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012

23 Thank You for your attention PRESENTED BY Jens Vollpott Regional Sales Manager KROENERT GmbH & Co KG Schützenstraße 105, D Hamburg, Page 23 - Jens Vollpott, KROENERT Hamburg - AIMCAL Web Coating Conference, Prague 2012 All photos and grafics by KROENERT