MORE OR LESS SILICONE

Transcription

1 Dr. Hans Lautenschlager, Wacker Chemie AG CREATING TOMORROW'S SOLUTIONS

2 HOW MUCH SILICONE DO YOU NEED? Tapes Labels Application Packaging tapes Electronic applications Clear on Clear Labels Silicone films paper Liner

3 WHAT ARE THE CRITERIA?

4 WHAT ARE THE CRITERIA? Perfect silicone layer Perfect separation of adhesive and substrate by the silicone

5 WHAT ARE THE CRITERIA? Potential defects pin holes scratches ablations streaking

6 WHAT ARE THE CRITERIA? Crosscuts of a label laminates

7 WHAT ARE THE CRITERIA? Crosscuts of different label laminates Hotmelt paper laminate Emulsion acrylic filmic laminate Emulsion acrylic paper laminate

8 WHAT ARE THE CRITERIA? FTM 25 for paper based liners Shirlastain A Malachite green Neocarmine A Methylene Blue Crystalline Violet Powder dye test for films Nigrosin dye Eye shadow Toner

9 WHAT ARE THE CRITERIA? Differences in paper stain tests 6 Color Index Y Differences in paper stain tests Shirlastain A standard lab test Methylene Blue Neocarmin Red Malachite Green Shirlastain [cn/25 cm] Malachite green recommended for color metric tests Neocarmine A recommended for yellow or brown papers Methylene Blue Lit.: Die Bestimmung der Silikonbeschichtung satinierter Rohpapiere mittels verschiedener Farbtests, B. Reinhardt, M. Hottenträger, V. Viehmeyer, COATING 5/94,

10 EFFECTS ON COVERAGE Rheology of the silicone system improved coverage with low viscous systems identical DELTA E values with 2% less coat weight DELTA E 4 35 higher DELTA E at identical viscosity by resin addition Low viscous system Standard system Low viscous system + CRA 2,4 2,2 2, 1,8 1,6 1,4 1,2 1,,8,6,4 Coat weight [g/m²]

11 EFFECTS ON COVERAGE Quality of substrate significantly improved coverage with new glassine types DELTA E Conventional Improved Extra 2,2 2, 1,8 1,6 1,4 1,2 1,,8,6,4 Coat weight [g/m²]

12 EFFECTS ON COVERAGE Quality of substrate on viscosity effect significantly improved coverage with new glassine types with low and high viscosity systems more pronounced effect with high viscous systems DELTA E 4 35 Low viscous system ,4 2, 1,6 1,2,8 DELTA E 4 35 High viscous system ,4 2, 1,6 1,2,8 Coat weight [g/m²],4,4 Conventional Improved Extra Conventional Improved Extra

13 EFFECTS ON COVERAGE Effect of cure on DELTA E significantly improved coverage by longer cure DELTA E 2 seconds cure Conventional Improved Extra 2,4 2, 1,6 1,2,8,4 DELTA E seconds cure ,4 2, 1,6 1,2,8,4 Coat weight [g/m²]

14 WHAT ARE THE CRITERIA? Effect of coat weight on release and release stability Accelerated aging and release test according to FTM 1 Low coat weights do not change aging performance coat weight limit depends on coating defect probability and sensitivity coating method substrate type of adhesive [N/m] ,5,8 1,1 1,5 2 2 h/4 C 4 w/4 C Coat weight [g/m²]

15 WHAT FACTORS ARE AFFECTED BY COAT WEIGHT? EFFECTS OF COAT WEIGHT ON COSTS Cost of silicone coat weight in a label laminate 5% of laminate cost 1%, if the laminate fails QC due to poor coverage 1 1%, if the liner fails at the customer due to poor coverage

16 WHAT FACTORS ARE AFFECTED BY COAT WEIGHT? EFFECTS OF COAT WEIGHT ON CURE Lower coat weight = Slower cure speed Strong effect of substrate Extractables [%] 5 coat weight,5 g/m² ,8 g/m² 1,1 g/m² 1,5 g/m² 2, g/m² 6,5 5,5 4,5 3,5 2,5 1,5 6,5 5,5 4,5 3,5 2,5 1,5 Clay Coated Paper Glassine Paper dwell time [s]

17 WHAT FACTORS ARE AFFECTED BY COAT WEIGHT? WHY DO LOW COAT WEIGHTS SLOW DOWN CURE? Inhibition by the substrate Interfacial segregation of the platinum (measured by Rutherford Backscattering Spectrometry) Extractables [%] 5 4 Silicone Catalyst Liner ,5 5,5 4,5 Cure time [s] 3,5 2,5 1,5 Lit.: Influence of Interfaces on the Rates of Crosslinking in Poly(dimethyl siloxane) Coatings, T. R. E. SIMPSON et al., Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 42, (24) 24 Wiley Periodicals, Inc.

18 WHAT FACTORS ARE AFFECTED BY COAT WEIGHT? EFFECTS OF COAT WEIGHT ON RELEASE level higher coat weight = lower release Substrate effect on coat weight changes Clay coated paper shows highest effect [N/m] 15 Coat weight [g/m²] 1,5,8 5 1,1 1,5 2, Clay Coat Glassine PE -Lami PET

19 WHAT FACTORS ARE AFFECTED BY COAT WEIGHT? EFFECTS OF COAT WEIGHT ON RELEASE PROFILE profile stronger effect of coat weight at high peel speeds Glassine; Linear Polymer; TESA 7475 [N/m] ,3 1 3,5 g/m²,8 g/m² 1, g/m² 1,5 g/m² 2, g/m² Peel Speed [m/min]

20 WHAT FACTORS ARE AFFECTED BY COAT WEIGHT? EFFECTS OF COAT WEIGHT ON SURFACE SMOOTHNESS Orange peel effect on filmic substrates low coat weights improve smoothness Microscopy of a coated film

21 EFFECTS OF SILICONE COAT WEIGHT Cost Cost Silicone cost Risk for claims,5 1 1,5 2 Cost of silicone Cost of claims Coat weight [g/m²] Performance Cure speed Smoothness Performance ,5 1 1,5 2 level Cure speed Orange peel Coat weight [g/m²]

22 HOW CAN WE CONTRIBUTE? PILOT COATER TESTING Corona 3 m Air flotation oven Coating heads 5-roll gravure offset gravure DIXON COATER Cure temperature: 8-2 C Coating speed: 1-15 m/min Dwell time:,6 18 sec. Systems: solventless, emulsions Roll width 25 cm

23 HOW CAN WE CONTRIBUTE? ANALYTICS OF SURFACES Applicable Methods s-sims SEM ESCA AFM 1nm SEM-EDX Raman IR RFA 1µm

24 HOW CAN WE CONTRIBUTE? IMPROVED SILICONE SYSTEMS Lower viscous silicone systems for improved coverage Silicone systems having an adjusted shear viscosity profile to cope with varying coater speeds DELTA E standard system low viscous system Viscosity [mpas] conventional system new system 5,5 1 1,5 2 2,5 coat weight [g/m²] Shear rate [1/s]

25 HOW MUCH SILICONE DO YOU NEED? MORE OR LESS IT S YOUR CHOICE