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Abrasive materials are classified as paper, nonwoven, or plastic-based multilayer structures, which are used for different kinds of surface finishing. Currently, the production of abrasive structures on textiles is carried out by spraying a slurry of binder and abrasive particles, e.g., Al2O3 or SiC, with subsequent drying and curing of the binder. The drawback of this production method is the poor runnability of the spraying process. Even small variations in the process parameters may lead to an uneven coating. Therefore, a novel coating approach was developed to produce abrasive structures with foam coating on textile substrates. The foam coating method, which is commonly used in the textile industry, has the potential to produce an even coating layer. The runnability and reliability of the foam coating process are good even with high solids. From a workplace safety perspective, another advantage of foam coating is that there are no airborne particles during the coating process. A polyamide woven cloth was foam coated with an aqueous slurry containing abrasive grains (SiC), a water-based UV-curable acrylate binder, and cellulose nanocrystals (CNCs) to adjust the slurry rheology. Stable abrasive-binder foams were generated from the slurries even at high solids of 50% using an anionic foaming agent. The cloth was foam coated and dried, and the resin was cured with a LED-UV lamp on a pilot scale. It was observed that without the addition of CNC the foam did not stay on the surface of the cloth after coating. CNC acts as a rheology modifier and co-binder, which prevent the foam from penetrating deeper into the pores of the cloth. CNC also acted as a dispersing agent: the slurry was effectively stabilized by the CNC to prevent sedimentation of the abrasive grains. An organic solvent-free composition was introduced by combining CNC with a water-based UV-resin.

The growth mechanism of Atomic Layer Deposition (ALD) on polymeric surfaces differs from growth on inorganic solid substrates, such as silicon wafer or glass. In this paper, we report the growth experiments of Al2O3 and ZnO on nonwoven poly-L-lactic acid (PLLA), polyethersulphone (PES) and cellulose acetate (CA) fibres. Material growth in both ALD and infiltration mode was studied. The structures were examined with a scanning electron microscope (SEM), scanning transmission electron microscope (STEM), attenuated total reflectance-fourier-transform infrared spectroscopy (ATR-FTIR) and 27Al nuclear magnetic resonance (NMR). Furthermore, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were used to explore the effect of ALD deposition on the thermal properties of the CA polymer. According to the SEM, STEM and ATR-FTIR analysis, the growth of Al2O3 was more uniform than ZnO on each of the polymers studied. In addition, according to ATR-FTIR spectroscopy, the infiltration resulted in interactions between the polymers and the ALD precursors. Thermal analysis (TGA/DSC) revealed a slower depolymerization process and better thermal resistance upon heating both in ALD-coated and infiltrated fibres, more pronounced on the latter type of structures, as seen from smaller endothermic peaks on TA.

Published under an ACS AuthorChoice license Novel coating materials are constantly needed for current and future applications in the area of microelectronics, biocompatible materials, and energy-related devices. Molecular layer deposition (MLD) is answering this cry and is an increasingly important coating method for organic and hybrid organic-inorganic thin films. In this study, we have focused on hybrid inorganic-organic coatings, based on trimethylaluminum, monofunctional aromatic precursors, and ring-opening reactions with ozone. We present the MLD processes, where the films are produced with trimethylaluminum, one of the three aromatic precursors (phenol, 3-(trifluoromethyl) phenol, and 2-fluoro-4-(trifluoromethyl)benzaldehyde), ozone, and the fourth precursor, hydrogen peroxide. According to the in situ Fourier-transform infrared spectroscopy measurements, the hydrogen peroxide reacts with the surface carboxylic acid group, forming a peroxyacid structure (C(O)-O-OH), in the case of all three processes. In addition, molecular modeling for the processes with three different aromatic precursors was carried out. When combining these modeling results with the experimental research data, new interesting aspects of the film growth, reactions, and properties are exploited.

The aim of this presentation is to demonstrate totally bio-based multilayer barrier packaging films. These films were prepared with a thin coating of fibrillated cellulose as an effective barrier against oxygen and/or mineral oil residues. It is shown that such films are feasible for packing of dry foods in formats such as bag-in-box, flexible pouches, and most recently in paper-based stand-up pouches. The cellulose fibrils can provide the films with a barrier suitable even for demanding products and for modified atmosphere packaging (MAP). For example, the bio-based MAP pouches containing ground hazelnuts were able to retain both their shape and internal atmosphere, while maintaining the original product quality. However, processes such as irradiation and aggressive compounds from the food product were found to impair the oxygen barrier provided by the fibrillated cellulose.

The aim of this presentation is to demonstrate totally bio-based multilayer films. These films were prepared with a thin coating of fibrillated cellulose as a barrier against oxygen and mineral oil residues. Such films are feasible for packing of dry foods in formats such as bag-in-box, flexible pouches, and most recently stand-up pouches. The cellulose fibrils can provide the films with a barrier suitable even for more demanding products and for modified atmosphere packaging.

Molecular layer deposition (MLD) is an increasingly used deposition technique for producing thin coatings consisting of purely organic or hybrid inorganic–organic materials. When organic materials are prepared, low deposition temperatures are often required to avoid decomposition, thus causing problems with low vapor pressure precursors. Monofunctional compounds have higher vapor pressures than traditional bi- or trifunctional MLD precursors, but do not offer the required functional groups for continuing the MLD growth in subsequent deposition cycles. In this study, we have used high vapor pressure monofunctional aromatic precursors in combination with ozone-triggered ring-opening reactions to achieve sustained sequential growth. MLD depositions were carried out by using three different aromatic precursors in an ABC sequence, namely with TMA + phenol + O3, TMA + 3-(trifluoromethyl)phenol + O3, and TMA + 2-fluoro-4-(trifluoromethyl)benzaldehyde + O3. Furthermore, the effect of hydrogen peroxide as a fourth step was evaluated for all studied processes resulting in a four-precursor ABCD sequence. According to the characterization results by ellipsometry, infrared spectroscopy, and X-ray reflectivity, self-limiting MLD processes could be obtained between 75 and 150 °C with each of the three aromatic precursors. In all cases, the GPC (growth per cycle) decreased with increasing temperature. In situ infrared spectroscopy indicated that ring-opening reactions occurred in each ABC sequence. Compositional analysis using time-of-flight elastic recoil detection indicated that fluorine could be incorporated into the film when 3-(trifluoromethyl)phenol and 2-fluoro-4-(trifluoromethyl)benzaldehyde were used as precursors. peerReviewed

Electrospinning is a method that can be used in the production of polymeric nanofibres. Polymer solution is drawn into sub-µm to nanosized fibres utilizing electric field. The structure of electrospun web has intrinsic properties such as small fibre diameter, small pore size, and high specific surface area which are beneficial for various applications. In addition, fibres can be functionalized in various methods. Thin (nm scale), conformal coatings made by atomic layer deposition (ALD) can be used for functionalization. For example, metal oxides can provide interesting properties, such as electronic, antimicrobial, self-cleaning and hydrophobic properties among others, to fibrous materials. Combining electrospinning and thicker ALD layer enables also preparation of sub-µm tubes, if core fibres are removed. Aim of this work was to make electrospun fibres from three polymers, cellulose acetate (CA), polyether sulphone (PES) and poly-L-lactide (PLLA) to be used as substrates for ALD. In this presentation we will report preparation electrospun fibres using solvent mixtures, structure of electrospun sheets (PLLA shown as an example), and preliminary results of ALD carried out on electrospun sheets, as well as discuss the possibilities of ALD method in functionalization and processing of electrospun fibres.

Atomic and molecular layer deposition (ALD and MLD, respectively) are based on repeated cycles of gas-solid surface reactions. A monolayer of precursor molecules is chemisorbed onto the surface during a single deposition cycle, enabling control of thin film growth in principle down to sub-monolayer resolution. This level of control has made ALD and MLD interesting for various applications. This presentation shows that low-temperature ALD can also be used to adjust wetting characteristics of polymer webs with non-ideal surfaces. For example, print quality can be optimized by surface modification with just few ALD cycles. We have also developed inorganic-organic hybrid materials providing, for example, improved adhesion between an inorganic oxide surface and extrusion coatings. These open up new application areas for ALD and MLD. Due to e.g. the small amount of deposited materiaL/cycles needed this could also help to alleviate the challenges related to the limited speed of roll-to-roll ALD processes.

Atomic layer deposition (ALD) is a layer-by-layer deposition process based on repeated self-limiting gas-solid reactions by using volatile precursors. It is suited for producing dense and pinhole-free inorganic nanoscale coatings uniform in thickness at relatively low temperatures. The purpose of this presentation is to demonstrate the potential and the challenges of using ALD to create functional coatings for polymer films. ALD is an efficient tool for improving the barrier properties of polymer films. However, adequate barrier properties are only one of the key requirements set for the packaging materials. As far as safety issues are concerned, these coatings, for example, seem not to fall under the European definition of nanotechnology and migration is low enough to meet the requirements set by current European regulations. ALD can also be used to create antimicrobial coatings, and thin oxide coatings can be modified for improved mechanical and surface properties. It is recommended that ALD coatings are protected with an additional polymer layer providing also heat sealability. Although ALD is today carried out in batch mode, the development of roll-to-roll processes will enhance the feasibility of ALD for e.g. packaging materials

Atomic layer deposition (ALD) is a surface controlled layer-by-layer process based on self-limiting gas-solid reactions. Thin films are prepared using volatile precursors in repeating cycles until a preferred film thickness is obtained. ALD is suited for producing dense and pinhole-free inorganic films uniform in thickness. Most important commercial applications lies today in microelectronics, but they range from displays to protective coatings on silver jewellery. The purpose of this presentation is to demonstrate both the potential and the challenges of using ALD to create thin barrier layers for packaging materials. ALD can have a profound effect on the barrier values of various polymer films and polymer coated paperboards. As far as safety issues are concerned, these thin barrier films seem not to fall under the European definition of nanotechnology and migration is low enough to meet the requirements set by current European regulations. ALD can also be used to create antimicrobial thin films, and thin oxide films can be modified for improved mechanical and surface properties. It is recommended that ALD deposited thin films are protected with an additional polymer layer also providing heat sealability. Although ALD is today carried out in batch mode, the development of roll-to-roll processes will enhance the techno-economic feasibility of ALD, among others, for packaging materials.

Foam coating is a promising method for applying a thin pigment layer of nanoparticles on a paper web. The interest in applying a low coat-weight coating layer arises from the need to create new functional surfaces using small amounts of new, typically expensive nanoparticles. The characterisation of thin pigment layer properties is more demanding than analysing traditional pigmented coatings layers because of the low coat weight (0.3-2.0 g/m2) and a corresponding low layer thickness of 1 µm or less. This characterisation requires surface sensitive measuring techniques and a combination of different microscopic and spectroscopic surface analyses. In this study, the pigment layer structure and chemical properties of nanosilica-coated paper were analysed. The results were utilised in the development of the foam coating process

Possibility to control the adhesion properties is important in various industrial applications. Since the topmost surface layers have the greatest role in adhesion thus making surface-controlled atomic layer deposition (ALD) reactions appealing method for tailoring surface adhesion properties. In this presentation we show that ALD and molecular-layer-deposition (MLD) can be used to adjust wetting characteristics of polymers and metals. Recently we have been modifying surface properties for various applica-tions including ink-jet printed films, adhesion promoting layers for extrusion coatings and anti-ice coatings. In addition to conventional inorganic metal oxides, such as Al2O3, we have tested also inorganic-organic hybrid MLD materials. Various tools, such as XPS, FT-IR and TOF-ERDA, were used to characterize these films, and wetting behavior was determined using contact angles measurements with the sessile drop method

Atomic and molecular layer deposition techniques have been successfully combined to produce inorganic-organic hybrid films with properties derived from both the inorganic and organic components. There are few reports dealing with further converting of ALD/MLD thin films. Typically inorganic oxide layers on polymer films in most cases require an additional top layer to enable heat sealing and to protect the thin film from mechanical stresses and defects. Adhesion of low-density polyethylene, polyethylene terephthalate and polylactic acid on ALD Al2O3 have been tested previously, where good adhesion was achieved in most cases only with the low-density polyethylene. In this study we report deposition of a hybrid ALD/MLD layer, its properties, as well as its use as adhesion layer for polyactic acid (PLA) extrusion coatings. A mixture of both lactic acid optical isomers, D- and L-lactic acids, was used as MLD precursor. 25 and 45 nm thick hybrid films were analyzed. XPS analyses gave a quite similar composition for both of these two coatings. FTIR analyses also indicated presence and bonding of hybrid components. The oxygen to carbon and oxygen to aluminum ratios were in line with theoretical calculations for such a hybrid. Deposition mechanism is expected to involve both hydroxyl groups of the lactic acid. However, the results indicated also other types of bonding between lactic acid and TMA or between the lactic acid molecules. The thickness of the hybrid remained the same for at least a week after the deposition indicating certain level of stability. In next step cellophane film deposited with 25 nm Al2O3 and 13 nm TMA-lactic acid hybrid was used as a substrate for PLA extrusion at different melt temperatures. Uncoated cellophane and BOPLA were used as reference substrates. PLA adhered only to itself and to the ALD/MLD hybrid with peel strength values exceeding 100 N/m, while PLA did not adhere to plain cellophane. Thickness of the MLD/ALD hybrid on ALD Al2O3 layer had no obvious effect on the adhesion properties at sealing temperature of 170 °C.

The purpose of this work was to investigate, whether silica extracted from olivine can be used as a low-cost coating pigment of ink-jet paper. Using nitric acid, amorphous silica was produced from olivine. The silica was washed, dried, milled and treated in an ultrasonic bath to attain a particle size suitable for paper coating (

Foam coating technique has shown to be a promising method for applying a thin pigment layer of nanoparticles on a paper web. The interest in applying a low coat weight coating layer is to create new functional surfaces using small amounts of new, typically expensive nanoparticles. The characterisation of thin pigment layer properties is more demanding than analysing traditional pigment coatings layers because of the low layer thickness of 1 µm or less with a coat weight of between 0.3 and 2 g/m2. This characterisation requires surface sensitive measuring techniques and a combination of different microscopic and spectroscopic surface analyses. In this study, the pigment layer structure and chemical properties of nanosilica-coated paper were analysed. The results were utilised in the development of the foam coating process

In this study on-line measurement devices were utilized to clarify how the changes in fountain solution properties affect formation of non-image area piling during printing. On-line measurements of pH, conductivity, redox potential, temperature, and calcium content were installed to measure fountain solution quality. Chemical impurities in the fountain solution cycle are mainly due to dissolution of ink. The dissolution increases concentration of dissolved cations such as aluminum and calcium, which increases hardness and conductivity. This has implications both to the press runnability and product quality. Non-image area piling on blanket originates from the plate. Ink spreads to the non-image area of the plate and ends up on the non-image area of the blanket. A part of it continues further to the paper. On-line measurements of water, ink pigment, and ink binder were used to follow the interactions of ink and fountain solution on plate and blanket. The findings were verified by visually observing the press with triggered micro-imaging. When fountain solution feed level is correctly adjusted, the main reason for the non-image area piling is poor ink stability on the plate. High amounts of cations in fountain solution may separate ink pigment particles from the ink binder. The phenomenon is seen as ink pigment particles on the non-image area of the plate, and it is significant especially when the same fountain solution has been utilized for a long period of time.