Trends in Surface Treatment for Multi-Layer Packaging

Transcription

1 Trends in Surface Treatment for Multi-Layer Packaging Presented by Senthil Kumar C.O.O. Enercon Asia Pacific

2 Major Presentation Topics Trends and Challenges Multi-Film Structures Wet vs. Dry Trapping on Inks, Coatings & Adhesives Chemistry Effects on Interlayer Adhesion Experimental using Atmospheric Plasma Technology Results & Discussion Conclusions

3 Trends & Challenges Multi-Film Structures Require structures which are: Clear Great barrier performance Can be used for retort to extend shelf life Technology enabling: Bio-films w/ ethylene copolymer tie layers for sustainability More layers, including micro- and nano-layers Must ensure no misfit with adhesive layers to avoid structural destabilization, decreasing interfacial adhesion

4 Trends & Challenges Multi-Film Structures As consumer marketplace expands globally, surface pretreatment requirements challenged: New material combinations More 9-10 layer tear-resistant constructions required Nano-multilayer films requiring increased printability, scuff resistance, high transparency, security. Flexible packaging converter trend toward higherspeeds, and away from inks which emit VOCs toward W/B and UV/EB curables.

5 Propositions Polymer film surface modification techniques improve acceptance of interfaces. These techniques increase hydrophilic characteristics and surface free energy. Interlayer adhesion can be improved by applying high density, homogeneous surface modification techniques

6 Propositions Atmospheric plasma surface modification discharges are high density, non-filamentary, uniform, create hydrophilicity. Study examines experimental data relating correlations between surface modification and interfacial adhesion effects.

7 Surface Modification Prerequisites Adhesion strength of inks, coatings, adhesives to polymers is relative to surfaces which are cleaned, microroughened, polarized and made hydrophilic. Accomplished commercially by Web corona discharge (air plasma), flame plasma, variable chemistry plasma techniques

8 Web Corona Surface Activation Systems

9 Web Flame Surface Activation Systems

10 Web Variable Chemistry Surface Activation Systems

11 Measuring Success Peel Adhesion Lap Sheer Tensile Tests Fatigue/Tear Tests

12 Wet vs. Dry Trapping on Inks, Coatings & Adhesives Multiple interfacial layer adhesion sub-optimized. Rely on formulation chemistries for wet-to-wet, wet-todry adhesion, for in-line and off-line processes. Example 1: dry-trapping 2 nd pass through printer, solvent-based interfaces can flake off due to wax content at surface layer. Example 2: chalking effect due to insufficient pigment binder for substrate adhesion. Example 3: binding-solvents and -oils drain through porous substrates, increasing delamination potential.

13 Wet vs. Dry Trapping on Inks, Coatings & Adhesives Water-based interfaces formulated w/non-water soluble binders composed of styrene-acrylic alkali-soluble binder and resin emulsion.

14 Wet vs. Dry Trapping on Inks, Coatings & Adhesives As interfaces dry, ammonia and volatile amines leave and emulsion particles can touch, combine to form a surface film.

15 Wet vs. Dry Trapping on Inks, Coatings & Adhesives However, trapping these interfaces can trap volatile amines which can exist as salts, interfering with interface-to-substrate bonding.

16 Experimental Objective Determine effectiveness of an appropriate surface pretreatment technology in promoting /optimizing dry trap interlayer adhesions. Protocol Atmospheric plasma pre-treatment of polypropylene substrate Establishment of base interface adhesion-to-substrate threshold. Re-treatment over base interface to determine appropriate wet-out/adhesion.

17 Experimental Process Variables Specification Additional Specifications Substrate BOPP film 0.5 mil. Pre-Treat Surface Tension 30 mn/m Dyne solutions/contact angle Water-Based Ink INX Lamiall Cyan none Solvent-Based Ink INX Lamiall White PU-based; Acetate, alcohol Treatment System Enercon Plasma Argon + oxygen Treatment Density 6W/ft 2 /min Base and interlayer Ink Application Method Pamarco Hand Proofer 165 line engraved roller Ink Drying Method Hot Air Dryer 1 min. ; 4 min. room temp. Test Ink Adhesion Method ASTM F M Scotch 800 tape; 180⁰

18 Experimental Material: Polypropylene Treatment: No post-treatment Pre-Treat Tension: 37 mn/m Result: 95% peel of ink Material: Polypropylene Treatment: Atmospheric Plasma Post-Treat Tension: 48 mn/m Result: <1% peel of ink Base & Interlayer Adhesion Tape Peel of Blue Water-Based Ink on White Background

19 Experimental Material: PP + Solvent ink layer Treatment: No post-treatment on solvent ink layer Pre-Treat Tension: 30 mn/m Result: Spotty interlayer adhesion Material: BOPP + Solvent ink layer Treatment: Atmospheric Plasma over first ink layer Post-Treat Tension: 39 mn/m at ink Result: >99% interlayer adhesion Base & Interlayer Adhesion Tape Peel of Blue Water-Based Ink on White Background

20 Experimental Material: Polypropylene Treatment: No post-treatment Pre-Treat Tension: 37 mn/m Result: 100% peel of ink Material: Polypropylene Treatment: Atmospheric Plasma Post-Treat Tension: 48 mn/m Result: <1% peel of ink Base & Interlayer Adhesion Tape Peel of White Solvent-Based Ink on Black Background

21 Experimental Material: PP + Solvent ink layer Treatment: No post-treatment on solvent ink layer Pre-Treat Tension: 31 mn/m Result: Spotty interlayer adhesion Material: BOPP + Solvent ink layer Treatment: Atmospheric Plasma over first ink layer Post-Treat Tension: 40 mn/m at ink Result: >99% interlayer adhesion Base & Interlayer Adhesion Tape Peel of White Solvent-Based Ink on Black Background

22 Results & Conclusions 1) Dry-trapping of solvent/solvent and water-base/waterbase inks with common formulations and without interlayer surface pre-treatment created poor adhesion. 2) Plasma pre-treatment of base layer to a minimum of 8 mn/m above base dry ink film layer surface tension = >99% interlayer adhesion on polypropylene. 3) Indication of inherent benefit in modifying base layer of dry-trapped inks. 4) Micro-etching of ink surface + removal of wax films 5) Oxygen formed hydroxyl groups and molecular bonds 6) Additional trials suggested to improve interlayer adhesion between coatings, adhesives, paints, etc.

23 Thank You for your attention!

24