Chemical resistance and cleaning properties of coated glazed surfaces

The effects of sol–gel-derived ceramic titania and zirconia coatings on staining resistance and cleanability of two matt and one glossy glazed tile were characterized. The surfaces were soaked in a weakly alkaline detergent solution in order to imitate the influence of normal household detergents on the surface properties. The soaking caused the water contact angle of the surfaces to decrease and also changes were observed in the average surface roughness. The surfaces were soiled with one color marked and two radiochemically labeled soil mixtures of oils and inorganic or organic particles. Under normal laboratory illumination conditions, the soils consisting of oil and inorganic particles were more easily cleaned from the surfaces than the soil with oil and organic particles. All surfaces soiled with the color marked mixture were also studied under exposure to UV light. The titania coating increased the cleanability and also showed self-cleaning capability after exposure to UV light, whereas exposure to UV increased the soil adherence to the zirconia-coated surfaces.     

Zusammenhang von Adhäsion und Reinigung von Mikropartikeln auf strukturierten Oberflächen

Adhesion of microparticles to surfaces is important for a number of industrial applications. Currently it is assumed that the adhesion between particles and surface needs to be resolved for a successful removal of unwanted particles in a cleaning process. It is supposed that the ability to remove particles from the surface correlates directly with the adhesion force measured by atomic force microscopy. Experiments are conducted with silicon‐ and stainless steel probes with various surface structures. An evaluation of the factors influencing adhesion and cleanability is performed.     

Effect of coating on cleanability of glazed surfaces

The aim of this study was to establish the effects of different coatings on the cleanability of glazed ceramics. The surface properties were examined with a contact angle meter, a contact profilometer and a confocal microscope. The surfaces were soiled with three radiochemical model soils: inorganic particle soil, organic particle soil and oil soil. Soil adhesion on surfaces was measured with a quantitative radiochemical procedure. Generally, cleanability of the particles present in the model soil was found to be affected by the roughness of the surfaces; however, the cleanability of the oil in the model soils correlated with the contact angle of water on the surfaces. Coating of glazes, especially with fluoropolymer film, generally increased the contact angle values. The coatings affected the cleanability of ceramics somewhat: particle soils were removed most efficiently from glazes coated with TiO₂ and Zr. By contrast the oil soil residues of the fluoropolymer surfaces were the lowest. The cleanability results of the three model soils based on inorganic or organic particles or oil were different indicating differences between the cleanabilities of these main components of the soils.     

Influence of Surface Roughness and Wettability of Stainless Steel on Soil Adhesion,Cleanability and Microbial Inactivation

Stainless steel is a material commonly used in the food industry. Numerous papers therefore have been published dealing with the influence of its characteristics on fouling, cleaning and disinfection. In most cases the authors refer to qualitative and quantitative aspects of the contact surface, e.g., topography. Some of these researchers additionally looked at the qualitative role of surface wettability. However in none of these papers was the analysis extended to identify and quantify a possible combined or synergistic influence of roughness and wettability. To clarify this question the author analyses the data base and results of three existing papers with respect to such a combined influence on soil adhesion, cleanability and microbial inactivation. The analyses show that surface roughness and contact angle in fact are of particular importance: double linear regressions based on both (appropriately converted) independent variables improve the coefficients of correlation to about 0.99, compared to approaches regarding roughness only: 0.76 (adhesion, inactivation) and 0.89 (cleanability). The results also support previous findings that with respect to the interesting surface effects the roughness Rz seems to be a better indicator of the surface topography than the roughness Ra, usually preferred for these kinds of investigations. The new insight can now serve as a guideline for further research on the influence of ‘topography and wettability’ on hygienic features of stainless steel surfaces for the food industry.     

Improving the cleanability of melamine‐formaldehyde‐based decorative laminates

Decorative laminates based on melamine formaldehyde (MF) resin impregnated papers are used at great extent for surface finishing of engineered wood that is used for furniture, kitchen, and working surfaces, flooring and exterior cladding. In all these applications, optically flawless appearance is a major issue. The work described here is focused on enhancing the cleanability and antifingerprint properties of smooth, matt surface‐finished melamine‐coated particleboards for furniture fronts, without at the same time changing or deteriorating other important surface parameters such as hardness, roughness or gloss. In order to adjust the surface polarity of a low pressure melamine film, novel interface‐active macromolecular compounds were prepared and tested for their suitability as an antifingerprint additive. Two hydroxy‐functional surfactants (polydimethysiloxane, PDMS‐OH and perfluoroether, PF‐OH) were oxidized under mild conditions to the corresponding aldehydes (PDMS‐CHO and PF‐CHO) using a pyridinium chlorochromate catalyst. With the most promising oxidized polymeric additive, PDMS‐CHO, the contact angles against water, n‐hexadecane, and squalene increased from 79.8°, 26.3° and 31.4° for the pure MF surface to 108.5°, 54.8°, and 59.3°, respectively, for the modified MF surfaces. While for the laminated MF surface based on the oxidized fluoroether the gloss values were much higher than required, for the surfaces based on oxidized polydimethylsiloxane the technological values as well as the lower gloss values were in agreement with the requirements and showed much improved surface cleanability, as was also confirmed by colorimetric measurements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40964.     

Evaluation of durability and cleanability performances of protective treatments for lapped ceramic tiles - Part 2

The aim of this work is to evaluate the cleanability performances of lapped porcelain stoneware surfaces with and without protective treatments. The knowledge of the material cleanability is an important selection parameter in buying tiles. However, an objective basis for testing and assessing this property still is lacking. In this study, standardized and laboratory tests to evaluate the cleanability performance of lapped porcelain stoneware products have been carried out and compared. Cleanability tests were performed by applying two different soiling suspensions, optimized for tile surfaces and reproducing chemical and mechanical actions simulating the working conditions and traditional cleaning operations. Surface characteristics (microstructure, topography, roughness) were analyzed before and after cleanability tests. The results showed a good correlation between different behavior in terms of cleanability and the microscopic and topographic characteristics of lapped tile. Respect to international standardized tests specific for ceramic tiles, such as stains resistance test, the laboratory procedures to evaluate the surface cleanability are able to better show cleanability improvements of lapped tiles with protective treatments.     

Microstructure and cleanability of uncoated and fluoropolymer,zirconia and titania coated ceramic glazed surfaces

The aim of this investigation was to examine the effect of surface topography of different compositions and surface coatings of glazed ceramic tiles on their cleanability. The cleanability was estimated with color measurements. Contact angle measurements were used to describe the surface properties and profilometry and electron microscopy to describe the topography. The effect of additional coatings on the surface properties was compared by applying experimental zirconia and titania coatings as well as a commercial fluoropolymer coating on one of the experimental and all reference glazes. The results show that there were clear differences between the soiling tendencies of the glazes. Generally the topography measurements show that the rougher was ceramic glaze, the more soil adhered on its surface.     

Enhancement of hybrid sol–gel coating and industrial application on polished porcelain stoneware tiles and investigation of the performance

The aim of this study was to improve stain resistance and cleanability of polished porcelain tiles by sealing the micro-pores on the tile surface with hybrid sol–gel solution. For this purpose, solutions of a hybrid system based on sol–gel technology were prepared. The obtained solution were applied to polished unglazed tiles and subsequently spread with soft tissue thereon. To achieve complete sealing, both organic and inorganic particles of different sizes were mixed with obtained sol–gel hybrid systems. Coated surfaces were investigated by means of a scanning electron microscope. The stain resistance and the cleanability of the tile surface were tested according to ISO-10545-2014 standard. It has been shown that prepared sealing material permanently prevents formation of stains such as olive oil, green staining paste, iodine solution on the surface of polished porcelain tiles. The remains of stains on the surface can easily be removed from it with a cleaning agent.     

Self‐Cleaning and Antibacteric Ceramic Tile Surface

The aim of this investigation was the surface functionalization of industrial ceramic tiles by sol‐gel technique to improve at the same time the cleanability and the antibacterial activity of surfaces. This objective was pursued through the design and preparation of nanostructured titania‐silver coating that was deposited on glazed, unglazed, and polished tiles by air‐brushing. The obtained results showed that the applied coatings are transparent, show a good adhesion, and a remarkable antibacterial activity under the tested conditions. The surface photocatalicity was optimized with the higher thermal treatments (200°C) even if photodegradation process is clearly affected by the sample surface roughness.     

Ein neuer Ansatz zur Charakterisierung der Flüssigphasenadsorption an Aktivkohlen

Activated carbons are widely applicable in industrial adsorption processes. However, characterization of their surface properties is problematic due to the number of different source materials and variations in production processes. Here, a model of the carbon surface derived that is based on the knowledge of fundamental molecular interactions on carbon surfaces. Adsorption isotherms of selected probe molecules are measured on different activated carbons and discussed how the model can be applied in the characterization of the surface properties of activated carbons.     

Fluorinated additives for stain-resistant matt latex paints

Latex paints are often preferred over solvent-based paints due to their good gloss and color retention, ease of handling, and lower volatile organic contents. However, matt latex paints tend to show poor stain resistance since they develop highly porous and rough surfaces. In recent years, matt latex paints have been improved in their stain resistance with resulting better cleanability, by adding hydrocarbon acrylic polymers and fluorine-containing compounds. In this work, we prepared fluorinated acrylic emulsions of the copolymer of butyl acrylate (BA) and perfluorobutylethylene (PFBE), which were introduced in latex paint compositions. The properties of the modified paints were evaluated by performing stain resistance tests with several domestic products. It was observed that they had good stain release properties, thus conferring good properties to the final painting system. They contain the self-cleaning behavior typical of fluorinated coatings, which have been proven by the decrease of their surface energies. Since the cleaning procedures of a matt paint film can also impart some gloss increase, the wet and dry burnishes were also evaluated. The results have shown improvements in stain resistance and cleanability of the modified matt latex paints with the maintenance of their stability and the coatings gloss as required.     

Beurteilung der Reinigbarkeit von Oberflächen bei partikulärer Kontamination

Hygienic impeccable surfaces are, e.g., in food technology and healthcare facilities conditionally essential. Does a presence of fine particular contamination occur, adhesion forces between particles and surfaces are relevant. In this paper the cleaning‐process of materials, which are often used in cleanrooms are focused. The surface properties, which influence the dislodgement of particles are observed. There are two groups of materials used for the experiments, which are commonly used in hygienic relevant places in healthcare facilities.     

Perspektiven der Säure‐Base‐Methode zur Untersuchung der Oberflächeneigenschaften von Polymeren

Modern methods for determining the surface free energy and their parameters were analyzed in the context of the presented investigations. The method of Berger and van Oss‐Chaudhury‐Good were found as the most suitable method for the determination of wetting solid polymer surfaces. Methods of nonlinear systems by Della Volpe and Siboni were evaluated and adapted. Various data of the surface free energy as well as its components have been identified for a number of polymer surfaces by application of spatial equation solutions.     

Antibacterial melamine resin surfaces for wood-based furniture and flooring

Melamine resin coatings are commonly used for particleboard and fiberboard products for interior applications such as work surfaces, furniture, and laminated wood flooring. In certain environments such as hospitals and kitchens, high hygienic requirements are set for most surfaces. Despite the comparatively good cleanability of melamine-coated surfaces, there is a need for improving their antimicrobial properties. The present paper discusses the different methods that are currently available or could be suitable for improving the hygienic properties of melamine-coated wood materials.     

Experimentelle Untersuchung zur Foulingneigung einer Polymerdispersion auf modifizierten Oberflächen

Fouling is economically and ecologically a key problem for the efficiency for production and processing of polymer dispersions. In this study, the fouling behavior of polymer dispersions on heated and cooled surfaces was investigated. Therefore, the dependency of the fouling on operational parameters (heat flux density, bulk temperature, concentration of solid, flow regime) and properties of the apparatus (surface modification, coating) was studied. Electropolished surfaces and certain sets of operational parameters were identified as fouling mitigating and easier to clean, respectively.     

Cleanability of Surfaces from Active Pharmaceutical Ingredient Surrogate Riboflavin by Falling Film

Falling films in wash down process are of major interest for pharmaceutical isolators, which are used for processing of highly potent pharmaceutical products. In this study multiple process parameters were examined with common materials of isolator systems. The importance of material and surface finish in respect of cleanability and complete wetting as well as a combination of process parameters are presented and discussed. For cleaning validation an effect of high interest was discovered: swab sampling areas changed their properties over many repeated cycles and showed decreased cleanability.     

Corrosion resistance and cleanability of glazed surface

This work aimed to study the effect of surface properties on the corrosion resistance and cleanability of glazed surface. The samples were zircon-containing raw glaze, zirconium-based frit glaze, double-glazed transparent glaze, and raw glaze coated with TiO₂ film. The corrosion resistance of the samples in acidic, alkaline, and household detergent solutions was investigated by the changes in contact angle and surface roughness. Besides, the cleanability of the samples before and after corrosion was also compared. It was found that the corrosion resistance of a glaze was affected by the presence of crystals and their distribution, while the corrosion resistance of TiO₂ film was closely related to itself and the nature of the substrate. The cleaning test showed that although adding a layer of transparent glaze reduced the surface roughness, it did not improve the cleanability. The TiO₂ film had excellent cleaning performance, especially after ultraviolet light irradiation, but it had weak alkali corrosion resistance. Therefore, a zirconium-based frit glaze is the right choice for sanitary ware in terms of durability and easy cleaning.     

Effects of UV-radiation on the cleanability of titanium dioxide-coated glazed ceramic tiles

The effects of UV-radiation on the cleanability of three glazed tiles coated with ceramic sol–gel derived TiO₂ were evaluated. A quantitative radiochemical determination method was used to measure oil and organic particle soil residues on the surface. Surfaces were characterized with topography and contact angle measurements. The observed effects of UV-radiation were greatest on rough surfaces, implying that increasing roughness increases the surface area available for photo-induced phenomena in the TiO₂-surface. Organic particle soil was removed more efficiently after UV-radiation than without UV treatment, whereas UV-radiation did not affect the removal of oil soil. Contact angles decreased significantly after UV-radiation.     

Relation between the cleanability of bare or polysiloxane-coated stainless steels and their water contact angle hysteresis

Cleaning of bare or coated stainless steel surfaces is investigated using some specific techniques for both particulate soil and oil removal. Particulate soil is removed from the surface by a water drop sliding, whereas oil is eliminated by shear flow of a commercial detergent. The cleanability performance is found to depend both on surface energy and topography. In general, the water contact angle hysteresis, which itself is related to the advancing contact angle and the surface roughness, is found to be an appropriate criterion for characterizing the cleaning performance. This finding is discussed in terms of retention and removal forces during the cleaning process and could provide in the future a criterion for material selection for industrial use of stainless steel surfaces.     

Contrôle hydrodynamique de l'evaporation d'un film liquide ruisselant sur une paroi isotherme à symétrie de révolution dans un courant d'air humide

A thin-film evaporation from a surface of a axisymmetrical body in a humid air stream was studied using a finite difference method associated with Thomas' algorithm. The surface of the body is supposed isothermal. The variability of physical properties is taken into account, and a steady-state and laminar regime is supposed. The influence of the main parameters of the system on the evaporation is determined, especially the wall profile. It is shown that, for certain conditions of calculation, it is possible to find a flat ellipsoid of revolution offering a uniformly accessible wall between the pole and the equator.