Functional Web Coating: from Food Packaging to Technical Applications

Transcription

1 Functional Web Coating: from Food Packaging to Technical Applications Stanislav Dribinskiy Materials Development Fraunhofer Institute for Process Engineering and Packaging IVV Giggenhauser Str. 35 D Freising

2 Business Fields of the Fraunhofer IVV

3 Functional Materials - Overview Polymer films with barrier and ultra-barrier properties or having selective permeability to permanent gases and vapors. Incorporation of functional components (scavengers and indicators) into composite films for technical applications. Dep. Materials Development Small pilot plant Polymer processing Polymer modification Compounding of plastics Vacuum web coating via conventional or e-beam Production of single or evaporation multi-layer flat films or blown films Lacquering and lamination of films and film Extrusion coating and composites extrusion lamination Manufacturing of barrier film composites by combining vacuum coating and lacquering BF 2 Functional Materials Materials testing Measurment of functional properties Determination of the permeability of packaging materielas to water vapor and oxygen Test on surface properties Determination of mechanical properties of packaging and packaging materials BF 4 Food Quality

4 Requirements for outstanding performance of polymer films Gas barrier and low out gassing Balance of mechanical, thermal, electrical and surface properties Chemical and optical performance customized to application Combination of long term thermal stability with dimensional stability Flame redundancy Weight reduction compare to standard materials: metal, ceramic and etc. Compromise needs to be obtained for a given application

5 Effects of oxygen plasma surface treatment on BOPP film Main objectives to gain a better insight into the adhesion mechanisms acting between the pre-treated BOPP film surface and the deposited aluminium layer establishment of a correlation between aluminium adhesion (via peel-test) and measured surface energy and plasma energy density Source: Schlussbericht Verbundvorhaben: Umweltentlastung in der Produktion und Nutzung von Verpackungen aus Verbundfolien durch Halbierung des Materialeinsatzes gefördert vom Bundesministerium für Bildung und Forschung (BMBF) Laufzeit des Vorhabens: bis characterisation of barrier properties (oxygen, moisture) of the aluminium coated BOPP film and the effect of plasma pre-treatment on barrier

6 Vacuum coater and plasma treater Plasma treatment levels: J/m², Plasma treater with power: 2 9 kw at 40 khz web speed: m/min 100% oxygen plasma Aluminium coating: Thermal evaporation, optical density of coated film: 2.0 Vacuum web coater at GVE (K4000) 1 Unwind 2 Plasma pre-treater 3 Evaporation unit 4 Coating drum 5 Non-contact eddy current resistance monitor 6 Rewind

7 Surface energy [mj/m²] Surface energy vs. XPS Corelation between XPS results and surface energy analysis Total Polar Dispersive Linear (Total) Linear (Polar) y = 1,4805x + 27 y = 0,7168x 0,0 2,0 4,0 6,0 8,0 10,0 12,0 Relative oxygen concentration [atomic-%] oxygen plasma species react with the film surface and create polar O- functional groups Correlation between surface energy and relative oxygen concentration obtained by XPS analysis

8 Aluminium adhesion the optimum for plasma treatment level etching of the BOPP film surface overtreatment formation of a low-molecular-weight polymer fragments layer high plasma treatment levels reduces the adhesion

9 Aluminium adhesion the optimum total surface energy of 35 to 37 mj/m² polar component between 3 and 5 mj/m² a high total/polar surface energy is an essential but not always a sufficient requirement to achieve good adhesion of the Aluminium coating

10 Roughness of BOPP No tendency observed with AFM-surface roughness measurements Correlation between surface roughness of BOPP film and plasma treatment level

11 What does this mean this g/m 2 d of water vapour? How much water would pass through this area over a MONTH at various barrier properties? ~ 100m ~50m Source: according to Alf Smith, The Centre for Process Innovation, GB Polymer Foil Food packaging OPV OLED

12 Oxygen Transmission Rate (OTR) and Water Vapour Transmission Rate (WVTR) WVTR (23 C, 85 % RH) OTR (23 C, 50 % RH) 1.6 g/(m 2 d) 1915 cm 3 /(m 2 d bar) Slight decreases of WVTR: average of 0.55 g/(m² d) Decreasing Oxygen Transmission Rate with increaising plasma energy density

13 Summary of main results Measured characteristic Change with plasma energy density ( J/m²) Surface energy Increase, constant level from 4500 J/m² on Roughness No clear tendency (possibly a slight increase compared to untreated film) Aluminium adhesion Maximum between 1500 and 3500 J/m² OTR Strong decrease, gradually levelling off WVTR Slight decreases optimal barrier properties optimal aluminium adhesion Compromise needs to be obtained for a given application

14 Project Elektroplas -Functional Coatings on PET Films Development and manufacture of ultra-thin barrier layer systems (thickness less as 2 microns) consisting of an inorganic barrier layer and a hybrid polymer coating layer for the PET protection against thermo-oxidative and hydrolytic aging Investigation of the fundamental influences of the coating on the electrical properties of the films Determination of the electrical and thermal aging performance to determine the temperature limit of the new film materials To show the roll-to-roll production possibility and transfer to pilot-application

15 PET Melinex 401 film after 4 hours at 180º C AFM 500x The crystal structure on the surface are cyclic oligomers, these are created at polycondensation of PET Melinex 401 film has about 1.1 wt% cyclic oligomers PEN Teonex film has about 0.3 wt% Source: Fraunhofer IVV

16 Functional Coatings on PET Films Water vapour Oxygen Temperature Functional coating Polymer film Functional coating

17 OTR [cm 3 /m 2 d bar] Gas permeability of polymers with the thickness of 100 µm Polymer + the single inorganic barrier layer LDPE Low Density Polyethylene HDPE High Density Polyethylene EVA/PE Ethylene-Vinyl-Acetate copolymer PS Polystyrole PC Polycarbonate PP Polypropylene BOPP Biaxiale Orientierted Polypropylene PVC Polyvinylchloride PET Polyethylenterephthalate PA 6 Polyamid 6 PAN Polyacrylonitrile PEN Polyethylene naphthalate PVDC Polyvinylidene Chloride EVOH Ethylene-Vinyl-Alkohole Copolymer ,1 CP LDPE EVA/PE PCL PS Celluloseacetat HDPE PP PVC weich PC BOPP PHB / V PLA, PUR BOPP/SiOx PVC hart PET Celluloseacetat/SiOx PLA/SiOx PA 6 PEN PAN ORMOCER PET/SiOx PVDC EVOH PUR Polyurethane 0, ORMOCER LCP Sol-Gel Lacquer Liquid Crystal Polymer WVTR [g/m 2 d] OTR: 23 C, 50 % re. Humidity; WVTR: 23 C, 85 --> 0 % re. humidity Source: Fraunhofer IVV

18 IVV- Vacuum coating machine with microwave plasma source and EB Plasma pre-treatment (e.g. using O 2, N 2 as reactive gases) High rate electron beam vacuum deposition Coating of paper and different substrate films with metals (e.g. Al, Cr, Ti), semiconductors (e.g. Si) or oxides (e.g. Al 2 O 3, MgO, SiO x and their mixtures) 3 1: coating drum 2: film (max. 28 cm wide) 3: EB evaporator 4: coating volume 5: microwave plasma source Analysis and monitoring of treatment and deposition processes Pilot-scale development of products and processes including scale-up in collaboration with external partners

19 PET Melinex 401/SiO x surface after 4 hours at 180º C AFM Transmitted light microscopy, SiO x -side Source: Fraunhofer IVV Crystals just on the uncoated side

20 Combination of an inorganic barrier layer and a hybrid polymer Defects filling in inorganic layer Ormocer SiO x Polymer ORMOCER from Fraunhofer ISC is an inorganic-organic hybrid polymer with heat-enhanced inorganic polycondensation and cross linking of the organic network. Cryo-transverse fracture preparation, recorded in high resolution SEM Source: Fraunhofer IVV

21 Reverse Gravure roll-to-roll coating Source: Fraunhofer IVV 1: gravure roll, 2: tub with application medium, 3: coating knife, 4: Presseur rubber covered roll, 5: film

22 IVV roll-to-roll lacquer pilot machine Source: Fraunhofer IVV Foil PET 1 pre-tratment Corona 2 Cleaning optional 3 Reverse Gravure 4 Consecutively heating at 120 C 5 Rewind 6

23 Gas permeation, film thickness range µm Layer structure OTR, cm³/m² d bar BIF WVTR, g/m² d BIF PET(Melinex ) 25 3 PET(Melinex )/SiO x /ORM 0,05/0,08 500/400 0,5/0,1 6/30 PET(Melinex )/ORM/SiO x 0, ,05 60 PET(Melinex )/SiO x 0, ,2 15 SiO x /PET(Melinex )/SiO x 4,21 7 0,6 5 ORM/SiO x /PET(Melinex )/SiO x 2,2 10 0,4 7 ORM/SiO x /PET/SiO x /ORM 0, ,25 12 SiO x /PET/ORM/SiO x /ORM 0, ,7 5 ORM/SiO x /PET/ORM/SiO x /ORM 0, ,5 6

24 PEN and PET/SiO x after 100 hours at 190 C PEN PET/SiO x Source: Project Elektroplas, Fraunhofer IVV

25 PET+SiO x +ORM4a after 100 hours at 190ºC PET/SiOx/ORM PET/ORM/SiOx Source: Fraunhofer IVV

26 elongation at break [%] Time, hours elongation at break [%] Accelerate life time, aging and thermo-effect on PET full scale aging PET 160 C - 1E9 1E8 1E ,00 200,00 175,00 150,00 125,00 100,00 75,00 50,00 25,00 0, Time[h] PET (MD) PET (TD) Polynomisch (PET (MD)) Linear (PET (TD)) Temperature full scale aging PET 180 C 225,00 200,00 175,00 150,00 125,00 100,00 75,00 PET (MD) PET (TD) Polynomisch (PET (MD)) Polynomisch (PET (TD)) 50,00 25,00 0, Time [h] Source: Fraunhofer IVV Source: Rudolf Brütsch et all, Insulation Failure Mechanisms of Power Generators, IEEE Electrical Insulation Magazine, July/August 2008 Vol. 24, No.4, 17-25p.

27 elongation Bruchdehnung at break, [%] % Accelerate life time, aging and thermo-effect on PET at 190 C Zugversuch: Vergleich verschiedener Materialien (MD), Alterung 190 C Zeit [h] Aging time, hours hard weicher mechanische Stabilität vorhanden stability spröder mechanical flexible 50%fall 50% Grenze PET (MD) PET/SiOx (MD) PET/SiOx/ORM (MD) PET/ORM/SiOx (MD) the mechanical properties of coated PET-films are dependent on the stretching of substrate film the SiOx-coating has a strongly negative effect on mechanical properties of PET-films Conclusion: different aging and degradation mechanisms at 160 C, 180 C and 190 C

28 WVTR [g/m 2 d] Changes in gas permeability and breakdown voltage after 30 hours at 190 C 100 % 90 % 80 % Permeationsmessung: Vergleich verschiedener Materialien Changes in gas permeability 70 % PET PET/SiOx PET/ORM/SiOx PET/SiOx/ORM Relative breakdown voltage changes after 30 hours loading at 190ºC PEN ,1 PET/SiOx/ORM 30 h 190 C PET/ORM/SiOx PET/SiOx/ORM PET/ORM/SiOx 30 h 190 C PET/SiOx 30 h 190 C PET 30 h 190 C PET PET/SiOx PET PET/SiOx PET/SiOx/ORM PET/ORM/SiOx PET 30 h 190 C PET/SiOx 30 h 190 C PET/SiOx/ORM 30 h 190 C PET/ORM/SiOx 30 h 190 C Source: Projekt ElektroPlas 0,01 0,01 0, OTR [cm 3 /m 2 d bar]

29 ElektroPlas main results thickness of the barrier system was 1 2 microns, barrier properties against oxygen ~ 10-2 cm³/(m² d bar) and water vapor ~ 10-2 g/(m 2 d) based on 50 micron thick substrate the breakdown voltage has not changed compared to the uncoated reference PET foil a new insights into the basic correlations between film topography, temperature stability and the resulting mechanical and barrier film properties a good aging stability of the coated films for short-term thermal storage (two weeks at 160 C, some layers combinations for one week at 180 C) reduction of growth of crystalline structures on PET surface (100 hours at 190 C) by application of barrier layers

30 Possible applications Thin Film Batteries Inorganic Thin Film Transistor back sheets Vacuum Insulation Panels Photovoltaic modules Organic electronics Hydrolysis resistant, heat stabilized, electrically friendly foils with temperature peaks of 170 C for Electric Motors High-temperature film for Capacitors Source:Siemens AG

31 Thanks to Prof. Horst-Christian Langowski, Dr. Klaus Noller, Dr. Kajetan Müller, Carolin Struller, Simone Moravec, Matthias Kohlmayer and Wolfgang Busch from Fraunhofer IVV Dr. Sabine Amberg-Schwab and Ulrike Weber from Fraunhofer ISC Dr. Christian Seidel from Siemens AG Nick Copeland, Graham Simpson and Robert Astbury from General Vacuum Equipment Ltd. Dr. Giovanni Schnelle from Kopafilm Elektrofolien GmbH Dr. Andreas Holländer fromfraunhofer IAP Thank you for your attention!