PLASTEK 2 Surface modification with plasma and corona techniques. VTT Advanced Materials Kalle Nättinen

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1 2 Surface modification with plasma and corona techniques Advanced Materials Kalle Nättinen

2 2 TECHNICAL RESEARCH CENTRE OF FINLAND Contents t Introduction t Technological background t Targets t Project organisation t Results t Future activities t Publications & conferences t Conclusions

3 3 Introduction t Plastek: A combination of two projects, Plastek and Plastek 2 Kick-off 2005 Timeline: 2006 Plastek 2007 Project extended: 3 months 2008 Plastek Jan. 2006: Lab plasma equipment in operation Running-in stage March 2006: Pilot plasma equipment installation Aug Pilot plasma operational Trial runs May 2008: New 4-electrode config. installed PDE: Running-in stage June 2008 Plasma deposition equipment installed PDE: Trial runs Pilot plasma operational PDE stage 2: Development & trials

4 4 TECHNICAL RESEARCH CENTRE OF FINLAND Technological background Corona treatment: electrical field of high frequency/voltage through the substrate Result: High energy electrical discharges activate the surface. - Fixed gas composition (air) - Inhomogeneity of the treatment Research targets - The electrical field is applied through the substrate -> Limitations to the substrate thickness and quality. AP (atmospheric plasma) treatment: Ionized gas & radicals + potentially other active components are separately produced and "extruded" Result: Continuous flow of ionized gas on surface. + High capacity, suitability for in-line process. + Higher durability + Possibility for coating + Tailored activation (N/O ratio, hydrophilicity, -phobicity) + No breakdowns through sample

5 5 Project organisation TUT/FMS TUT/PCT ÅA Laminates Equipment development & extrusion coating Functional laminates Sol-gel development Antimicrobial and barrier coatings Fibre materials Printing TUT/FMS: Tampere University of Technology, Fiber Materials Science TECHNICAL RESEARCH CENTRE OF FINLAND TUT/PCT: Tampere University of Technology, Paper Converting Technology Åbo Akademi Pappersförädling

6 6 TECHNICAL RESEARCH CENTRE OF FINLAND First stage (Plastek) targets: Research targets 1/4 t Installation of plasma treatment unit in the TUT Paper Converting pilot t Set up of in-line AP treatment suitable for industrial scale t Comparison of AP with corona: power, durability, speed, effect on surface chemical composition t Treatment of selected substrates and determination of the treatment effect t Study and enhance the laminate adhesion, printability and smoothness

7 7 TECHNICAL RESEARCH CENTRE OF FINLAND Plastek 2 targets: Laminates Research targets 2/4 t Optimization and increasing the treatment speed/power t Applying gas mixtures (methane, N 2, H 2 and NH 3 ) for tailored surface properties t Development of a plasma deposition system t Plasma deposition of active compounds, starting from HMDSO t Tuning of surface hydrophilicity/-phobicity, barrierproperties and antimicrobial properties t Pre- and post-treatment of sol-gel coated surfaces to enable in-line coating.

8 8 Research targets 3/4 Plastek 2 targets: Fibre Materials Special features of nonwovens in plasma treatments. Effect of porosity penetration of plasma with different gases. Surfaces consisting of several raw materials (model and theoretical surfaces). Finishing's of nonwovens. Interaction of plasma and additives. Enhancement of dielectricity and hydrophobicity of nonwoven filters.

9 9 Research targets 4/4 Plastek 2 targets: Printing Use of model inks for plasma treated surfaces Change polarity, acid and base character of the ink Sun Chemicals will provide model inkjet inks Substrates Use of model paper coating in addition to commercial papers Also polymer surfaces Rub resistance of the sol-gel coated printing products

10 10 Results Laminates Equipment development & Extrusion Coating in presentation by Mikko Tuominen (TUT/IPC)

11 11 Results Laminates Functional Laminates Project group: Kalle Nättinen, Tero Malm, Hannu Minkkinen Barrier properties LDPE Nanoclay compounds: new dispersion method. 86% improvement Chitosane biopolymer compounds. Target: improved barrier with reduced moisture sensitivity of OTR. Comparative analyses with plasma deposited coatings Activation decay POSS additives for increased activation stability Slower decay with acryl POSS substrate Treatment gas & distance studies Effect of using N 2, or Ar instead of air 7x increment in amount of N-content on surface Most efficient oxidation with N 2 Activation not increased linearly with decreasing distance: max. at 9 mm Equipment development PC-operated system for automated sample treatment with lab-scale plasma Plasma deposition equipment: Ongoing work

12 12 TECHNICAL RESEARCH CENTRE OF FINLAND Results Laminates Functional Laminates

modified with functional compounds and enzymes.

13 13 TECHNICAL RESEARCH CENTRE OF FINLAND Laminates Antimicrobial coatings: Results Wet-chemical coating of plasma-activated BOPP with bio-active compounds t Biobased polymers modified with functional compounds and enzymes. t Functionality, surface energy and barrier properties etc.

14 14 TECHNICAL RESEARCH CENTRE OF FINLAND Results SEM cross-sectional picture of chitosan coated plasma-activated BOPP film Vartiainen, Rättö, Lantto, Nättinen, Hurme. Packaging Technology and Science. In press (2008)

15 15 cm 3 /(m 2 *24h) Oxygen transmission of plasma-activated BOPP at 23 C no coating Chi Chi/DOGA Chi/OGA Chi/DOGA/Tyr-pH4 Results Chi/OGA/Tyr-pH4 Chi/DOGA/Tyr-pH6 Chi/OGA/Tyr-pH6 Vartiainen, Rättö, Lantto, Nättinen, Hurme. Packaging Technology and Science. In press (2008) 0% RH 50% RH 80% RH

16 16 -Results Enzyme-immobilized plasma-activated BOPP films with anti-inflammatory activity t=0 Enzyme (pure) Enzyme (immobilized on BOPP) t=10 min t=30 min t=60 min Antiinflammatory activity expressed as colour change t=210 min

17 17 TECHNICAL RESEARCH CENTRE OF FINLAND Sol-gel coatings - possibility for accurate surface modification Application of coatings on low surface energy substrates with plasma pre-treatment t Hybrid nanocomposites consisting of organically modified metal alkoxides Thin coatings; from nanoscale to 10 µm Transparent or pigmented - Results Dense or with controlled porosity t Nanocomposite properties are controlled by the chemical composition and process variables Abrasion and scratch resistance, barrier properties, soil repellancy and easy-to-clean surfaces Adhesion to different substrates, e.g. polyolefins is important New or combined properties: not only ceramic or polymeric but something else

18 - Results t Coated subtrates: PE-cardboard, BOPP, Lumiflex t Lab scale pretreatments with s atmospheric plasma Sol-gel coatings developed by were deposited after lab scale plasmatreatment:

18 18 - Results t Coated subtrates: PE-cardboard, BOPP, Lumiflex t Lab scale pretreatments with s atmospheric plasma Sol-gel coatings developed by were deposited after lab scale plasmatreatment: PLSG201, PLSG202, PLSG203, PLGS204, PLGS205, PLSG206, PLSG304, PLSG305 and PLSG306 t Trial runs in TUT s pilot line equipped with atmospheric plasma s sol-gel coatings PLSG204 and PLSG205 were spray coated after plasma pretreatment with different gases Sol-gel coating MD192 developed by Millidyne was also spray coated similarly after plasma t Heat treatment of coated specimens 110 C 10 min

19 19 - Results Wear resistance of PE-cardboard was improved by sol-gel coating Before abrasion After 1000r brush abrasion 14 g/cm 2 Uncoated PE-cardboard N-Plasma enhanced PLSG205 coated PE-cardboard Coating thickness: 5-8µm 20 x objective, image size 637x477 µm

20 20 - Results Oxygen transmission rate of PE-cardboard was decreased by sol-gel coating OTR RH50% PE-Cardboard cm3/(m2*24h) PLSG x spray PLSG x spray PLSG x spray PLSG x spray PLSG x spray PLSG x spray Ref

21 21 Results t During project TUT/FMS studied plasma-assisted polymer coating of cardboards. t Plasma treatment changed the contact angles of the cardboard regardless of the order of the treatments. 70 Contact Angle of Ethylene Glycoll No Plasma pat ppt ppt and pat Ref. A B C A, B and C are samples with different kind of PVA coatings having coating weight < 0.5 g/m 2. Plasma was used as pre-treatment (ppt) and after-treatment (pat).

22 22 : Fibre Materials t Another theme of project was plasma treatments of nonwoven fabrics with corona and different plasmas including He, N 2 and Ar. t Plasma penetrated into porous structure of nonwoven materials and its effects could be seen in deeper layers than just on surface. This is studied in Plastek2. t Contact angle measurement results of nonwoven materials were inconsistent, probably due to the porosity of the samples and too high hydrophilicity. Different methods for evaluation the effect of plasma will be used in Plastek2.

23 23 2: Fibre materials Study of plasma penetration Two polypropylene (PP) nonwoven samples: A with hydrophilic surface treatment, 23 g/m 2 B without surface treatments, 45 g/m 2 Plasma (Argon and Helium) and corona treatments were performed in atmospheric pilot line of TUT/Paper Converting to layered samples attached onto LDPE-base Contact angles were measured from the base material (LDPE surface) onto which the layered samples were attached, and also from B samples Capillary rise method to evaluate the effect of plasma on nonwoven materials.

24 2: Fibre materials Plasma penetrated through the nonwoven layers and the presence of nonwoven even increased the effect of plasma. Potential explanations: - Plasma may partially transfer e.g. the hydrophilic coating from the nonwoven to PE surface - Nonwoven sample may retain plasma gas longer in the vicinity of the surface.

24 24 2: Fibre materials Plasma penetrated through the nonwoven layers and the presence of nonwoven even increased the effect of plasma. Potential explanations: - Plasma may partially transfer e.g. the hydrophilic coating from the nonwoven to PE surface - Nonwoven sample may retain plasma gas longer in the vicinity of the surface. Water contact angles of untreated PE base (Ref), PE base treated using Argon plasma without sample cover (0) and with different amount of layers (1L-3L) of nonwoven samples (A and B).

25 2: Fibre materials Capillary rise test showed that the effect of plasma was strongest in the uppermost layers of the nonwoven samples and the effect was decreased with amount of layers.

25 25 2: Fibre materials Capillary rise test showed that the effect of plasma was strongest in the uppermost layers of the nonwoven samples and the effect was decreased with amount of layers. Capillary rise after 60 s of untreated and Argon plasma treated layered samples of nonwoven A. Other activities of Plastek2 in TUT/FMS will include e.g. the study of heterogenic nature of the sample and plasma-aided hydrophobic treatments of nonwoven materials.

26 TECHNICAL RESEARCH CENTRE OF FINLAND Results Printing group t Target: Improved Printability through Atmospheric Pressure Plasma Surface Treatment t Surface treatment: Lab-scale plasma &

26 26 TECHNICAL RESEARCH CENTRE OF FINLAND Results Printing group t Target: Improved Printability through Atmospheric Pressure Plasma Surface Treatment t Surface treatment: Lab-scale plasma & Pilot-scale plasma and corona t Printing methods: Offset, gravure, flexo, inkjet, electrophotography t Substrates: Uncoated and coated paper, extrusion coated paper/board, plastic films t Surface characterisation: Contact angle measurements, AFM, SEM, ATR, ToF-SIMS, XPS (ESCA) 26

27 Results 27 Mottle index t In offset printing of hydrophobic surface sized paper, plasma activation made absorption of fountain solution more even*) Plasma activation reduced water interference mottle t In flexo printing of PE-LD coated paper, plasma activation improved ink-substrate adhesion (i.e. rub-off) Surface sized, WIM Untreated N2-plasma He-plasma Corona 100% 75% 50% 25% Print density 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 INK-SUBSTRATE ADHESION (LDPE) Density, original Density, after 15 rounds of abrasion Untreated He-plasma treated N2-plasmaCorona treated treated *) Pykönen-Sundqvist-Tuominen-Lahti-Preston-Fardim-Toivakka: Influence of Atmospheric Plasma Activation on Sheet-Fed Offset Print Quality. Nordic Pulp and Paper Res. J. In Press

Results 28 Plasma treatment improved inkjet print

was achieved with He-plasma Line raggedness of

corona treated surface Raggedness (µm), PE and PP

Un-treated N 2 20 m/min He 20 m/min Corona 20

Plasma PE Corona Untreated PP PP N2 Plasma PP He

28 Results 28 Plasma treatment improved inkjet print quality on PE film With PE film, the best result was achieved with He-plasma Line raggedness of plasma treated surface was lower than that of corona treated surface Raggedness (µm), PE and PP films, Solvent based pigment ink Un-treated N 2 20 m/min He 20 m/min Corona 20 m/min Un-treated N 2 20 m/min He 20 m/min Corona 20 m/min 10 0 PE Untreated PE N2 Plasma PE He Plasma PE Corona Untreated PP PP N2 Plasma PP He Plasma PP Corona PE PP

29 29 TECHNICAL RESEARCH CENTRE OF FINLAND Results Surface energy t According to AFM measurements, micro scale roughness of pigment coated paper increased less with plasma treatment than with corona t Plasma activation increases surface energy and polarity of surface due to formed oxygen containing molecular groups rms roughness (Sq), nm Pigment coated paper Surface energy [mn/m] Surface sized Lumiflex Pigment coated Lumiflex Berga Laser 10 Untreated N2-plasma Corona Lab.-plasma 0 No treatment N2 Plasma He Plasma Corona Lab

30 Offset printing: t M.Sc. Thesis: Influence of Plasma Activation on Absorption of Ink Components and Dampening Water in Sheet-Fed Offset Printing Tentative results in poster session t To prevent peneration of UV overprint varnish into permeable pigment coated paper by plasma coating t Immobilisation of fountain solution in offset printing to prevent it from penetrating into the base paper and causing fluting and curl Inkjet printing: t To improve the understanding of ink - substrate interactions (i.e. impact of plasma treatment on substrate and effect of ink chemistry) by using model inks t To improve quality of conventional pigment based inkjet paper by plasma coating Electrophotographic & flexo printing: t To study influence of surface properties (surface energy, roughness, surface oxidation, etc.) on print quality of extrusion coated paper/board and plastic films Abrasion resistance of printed images Printing Ongoing Work Uniformity of plasma treatment vs. Print quality Backside treatment studies with plastic films 30

31 31 : Publications & conferences So far: t 17 Conference publications t 7 Papers t 3 Diploma thesis

32 32 TECHNICAL RESEARCH CENTRE OF FINLAND Conclusions t Construction of the modular plasma equipment completed t Verification of effectiveness by a test series t Positive results in comparison with corona: Lower backside treatment Higher activation level Higher durability Highlights: t Adjustable activation effect by a change of gas composition t Promising results with anti-inflammatory coatings t High O 2 barrier materials with chitosane and sol-gel systems

33 Acknowledgements ÅA/PAF Toivakka Martti ÅA/PAF Pykönen

Lahtinen Kimmo TUT/PCT Lahti Johanna TUT/PCT Kuusipalo

Peltola Minna TUT/FMS Nousiainen Pertti TUT/FMS

Ali TUT/FMS Hakkarainen Pirjo Vartiainen Jari Sundqvist

Kalle Nygård Mirja Nikkola Juha Murto Minna Minkkinen

33 33 Acknowledgements ÅA/PAF Toivakka Martti ÅA/PAF Pykönen Maiju TUT/PCT Tuominen Mikko TUT/PCT Lavonen Juho TUT/PCT Lahtinen Kimmo TUT/PCT Lahti Johanna TUT/PCT Kuusipalo Jurkka TUT/PCT Kela Timo TUT/FMS Väänänen Riikka TUT/FMS Peltola Minna TUT/FMS Nousiainen Pertti TUT/FMS Martikainen Liisa TUT/FMS Heikkilä Pirjo TUT/FMS Harlin Ali TUT/FMS Hakkarainen Pirjo Vartiainen Jari Sundqvist Henna Saari Juha Rättö Marjaana Pelkonen Johanna Nättinen Kalle Nygård Mirja Nikkola Juha Murto Minna Minkkinen Hannu Mansukoski Liisa Mannila Juha Malm Tero Hurme Eero Hakola Liisa Erho Tomi Eiroma Kim

Atomic Layer Deposition in Food Packaging and Barrier Coatings

Atomic Layer Deposition in Food Packaging and Barrier Coatings Cost Workshop 16 th September2011, Espoo Dr. Pirjo Heikkilä VTT Technical Research Centre of Finland 2 Outline of the Presentation Food packaging