Next generation vacuum deposited ALOx clear barrier coatings for flexible food packaging materials

In the field of packaging, barrier layers are functional films, which can be applied to polymeric substrates with the objective of enhancing their end-use properties. In the case of food packaging applications, the packaging material is required to preserve packaged foodstuffs and protect them from a variety of environmental influences. Amongst others, the impermeability of the packaging material to substances including water vapour, oxygen and aromas is an important requirement for successful food packaging. Polymer films, vacuum coated with thin transparent barrier layers of aluminium oxide or silicon oxide, are very attractive candidates for food packaging applications due to the oxide film imparting attractive properties, including good barrier performance, transparency, microwaveability and recyclability. In this project, aluminium oxide barrier layers were deposited onto various commodity grade BOPP films via reactive evaporation of aluminium, using a modified industrial ‘boat-type’ roll-to-roll metalliser. Optimisation of the deposited coating, in some cases together with potential surface modifications of the BOPP films, was the main focus of the work. The effects of different film treatments (in-line and off-line); surface properties of the polymer film, such as topography and chemistry; coating stoichiometry and thickness; as well as conversion processes; on barrier properties were investigated using a broad variety of analytical techniques. Furthermore, critical parameters for the convertibility of vacuum coated films, including coating adhesion and coating surface energy, were assessed. This project has demonstrated that the barrier performance of aluminium oxide coated BOPP is heavily dependent on the plain film surface and the growth/nucleation conditions of the deposited film, both of which can vary to a large extent on standard packaging grade BOPP film. Whilst acceptable oxygen barrier levels were achieved on some of the standard BOPP film types, others did not match the requirements, despite investigating a wide range of coating parameters. This was found to be due to the presence of defects (permeation pathways) in the coating, which were reproduced from defects in the underlying polymer film surface. With regards to the barrier performance after aluminium oxide coating, the polymer film surface chemistry was identified as an important parameter. Furthermore, oxygen barrier performance was significantly enhanced when a high surface energy polymer skin layer was co-extruded onto the BOPP film. Nevertheless, water vapour barrier improvement for aluminium oxide coated BOPP films was only achieved through the use of different polymer skin layers or via depositing coatings with reduced oxygen content, thus obtaining grey coatings that can no longer be classified as transparent. Peel tests indicated very high levels of adhesion of the aluminium oxide coating to the BOPP film, with cohesive failure taking place within the polymer, rather than adhesive failure at the coating-substrate interface. Examination of the time related change of surface energy revealed a distinct decay with ageing time, most probably due to transfer of polymeric material and film additives from the reverse side of the film onto the coating and also migration through defects in the coating. Finally, the application of acrylate under- and topcoats, as well as adhesive lamination, was found to have the capability to significantly enhance the barrier performance of the aluminium oxide coated BOPP film. In the case of acrylate undercoats, this was attributed to the change in surface chemistry, whilst for topcoats and lamination processes, the barrier properties of the acrylate/adhesive play an important role, together with a possible ‘pore filling’ effect

Conversion of aluminium oxide coated films for food packaging applications—From a single layer material to a complete pouch

© 2019 Elsevier Ltd Transparent barrier films based on vacuum deposited aluminium oxide (AlOₓ) layers are continuing to create large interest in the market with regards to their use as food and healthcare packaging materials. Nevertheless, their post-metalliser conversion to the final packaging material still presents challenges to current AlOₓ producers and the wider converting industry. In this work, AlOₓ coated polyethylene terephthalate (PET) films have been converted in long duration industrial-scale trials via topcoating, printing, lamination and finally pouch making. Throughout this process, each conversion step has been investigated for its effects on the barrier performance. It was found that the printing processes, especially, induce significant damage to the ceramic barrier layer. However, by the use of a protective topcoat prior to any conversion step, the barrier properties of the AlOₓ coated film were preserved, or could even be significantly enhanced, depending on the topcoat material. Furthermore, for a barrier topcoat, remarkable stretch- and flex-durability properties were achieved in the final laminate

Aluminium oxide barrier films on polymeric web and their conversion for packaging applications

In recent years, inorganic transparent barrier layers such as aluminium oxide or silicon oxide deposited onto polymer films have emerged as an attractive alternative to polymer based transparent barrier layers for flexible food packaging materials. For this application, barrier properties against water vapour and oxygen are critical. Aluminium oxide coatings can provide good barrier levels at thicknesses in the nanometre range, compared to several micrometres for polymer-based barrier layers. These ceramic barrier coatings are now being produced on a large scale using industrial high speed vacuum deposition techniques, here, reactive evaporation on a 'boat-type' roll-to-roll metalliser. For the thin barrier layer to be useful in its final packaging application, it needs to be protected. This can be either via lamination or via an additional topcoat. This study reports on acrylate topcoats, but also undercoats, on aluminium oxide coated biaxially oriented polypropylene films. The effect of the acrylate layer on barrier levels and surface topography and roughness was investigated. The acrylate was found to smooth the substrate surface and improve barrier properties. Furthermore, the activation energy for water vapour and oxygen permeation was determined in order to investigate barrier mechanisms. The oxide coated film was, additionally, converted via adhesive lamination, which also provided improvement in barrier levels. © 2013 Elsevier B.V. All rights reserved

Amorphous Alumina Barrier Coatings on Glass: MOCVD Process and Hydrothermal Ageing

Amorphous alumina coatings are applied on the inner surface of glass containers aiming at improving their hydrothermal ageing barrier properties. A direct liquid injection technology is implemented in a metal-organic chemical vapor deposition (MOCVD) process to feed the reactor in a controlled and reproducible way with a solution of aluminum tri-isopropoxide (ATI) in anhydrous cyclohexane. Amorphous alumina coatings are characterized by X-ray diffraction, electron probe microanalysis, scanning electron microscopy, atomic force microscopy and scratch-test method. They are amorphous and hydroxylated at process temperatures between 360 and 420 °C and close to Al 2 O 3 stoichiometry between 490 and 560 °C. Hydrothermal ageing simulated by a standard sterilization cycle results in the increase of the root mean square of the surface of the coatings from ≈17 to 61 nm and in the increase of the porosity without affecting the adhesion of the coatings on the glass substrates

Aluminum oxide barrier coatings on polymer films for food packaging applications

In the field of packaging, barrier layers are functional films, which can be applied to polymeric substrates with the objective of enhancing their end-use properties. For food packaging applications, the packaging material is required to preserve packaged food stuffs and protect them from a variety of environmental influences, particularly moisture and oxygen ingress and UV radiation. Aluminum metallized films are widely used for this purpose. More recently, transparent barrier coatings based on aluminum oxide or silicon oxide have been introduced in order to fulfill requirements such as product visibility, microwaveability or retortability. With the demand for transparent barrier films for low-cost packaging applications growing, the use of high-speed vacuum deposition techniques, such as roll-to-roll metallizers, has become a favorable and powerful tool. In this study, aluminum oxide barrier coatings have been deposited onto biaxially oriented polypropylene and polyethylene terephthalate film substrates via reactive evaporation using an industrial 'boat-type' roll-to-roll metallizer. The coated films have been investigated and compared to uncoated films in terms of barrier properties, surface topography, roughness and surface energy using scanning electron microscopy, atomic force microscopy and contact angle measurement. Coating to substrate adhesion and coating thickness have been examined via peel tests and transmission electron microscopy, respectively. © 2013 Elsevier B.V

Droša aborta pieejamība Latvijā COVID-19 pandēmijas laikā un ikdienā

MedicīnaVeselības aprūpeMedicineHealth CareVēl joprojām Latvija saskaras ar COVID-19 pandēmijas radītajām sekām. Jau vairāk nekā gadu medicīnas nozares darbiniekiem nākas strādāt neparedzama spiediena apstākļos. Mediķi ir spiesti reaģēt uz augsto hospitalizēto pacientu skaitu, kā arī pasargāt sabiedrību no potenciālas veselības sistēmas sagrūšanas, kuru pandēmijas laikā varēja novērot citās Eiropas valstīs. Šī pētnieciskā darba mērķis ir noskaidrot, kā pandēmija ir ietekmējusi aborta pieejamību Latvijā. Lai noskaidrotu aktuālo situāciju, ar aptaujas palīdzību tika apzināti ginekologi un dzemdību speciālisti, kuri ikdienā veic šo procedūru. Iegūtie dati un rezultāti tika analizēti apkopotās literatūras kontekstā saistībā ar pašievadi un telemedicīnas izmantošanu medicīniskajā abortā. Tika ņemta vērā arī citu Eiropas valstu rīcība pandēmijas laikā un to pieeja grūtniecības pārtraukšanas programmām. Apkopotie rezultāti uzrāda, ka aborta pieejamība ir samazinājusies, kā arī nav realizētas nekādas iniciatīvas un stratēģiska rīcība problēmas risināšanai. Taču pētnieciskajā darbā tika secināts, ka konkrētās izmaiņas notikušas kopējās veselības sistēmas pārorientēšanā COVID-19 situācijas risināšanas, nevis tiešu ierobežojumu noteikšanas abortu pieejamībai dēļ.Currently, Latvia faces the consequences of rising numbers of COVID-19 cases. For more than a year, medical providers work under fluctuating pressure. They have been required to respond to high hospitalisation rates and protect the public from a potential collapse of the health care infrastructure, which has been observed in other European countries. This study aims to determine how the pandemic has impacted access to abortion care in Latvia. A survey was distributed among OB-GYN specialists to assess the current situation. The following results were analysed in the context of the contemporary literature about self-administration and telemedicine in medical methods of abortion. Recent responses of other European countries to the pandemic and their pregnancy termination programmes were also taken into account. The analysis showed that access to abortion care has been diminished, and innovative strategies have not been implemented to solve related problems. However, it was concluded that these changes have been caused by healthcare institutions' overall involvement in the treatment of COVID-19 cases and not due to direct restrictions to abortion care