| 1. |
- Rentzhog, Maria, et al.
(författare)
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Rheology and surface tension of water-based flexographic inks and implications for wetting of PE-coated board
- 2005
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 20:4, s. 399-409
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Tidskriftsartikel (refereegranskat)abstract
- This study systematically characterises a matrix of water-based flexographic inks with respect to their rheology, surface tension and wetting of liquid packaging board, to provide a basis for interpretation and prediction of their printing performance. For all pigment and acrylate polymer vehicles and mixing proportions the inks were shown to be shear thinning and thixotropic, with plastic viscosity, yield stress and storage and loss moduli increasing strongly with content of solution polymer (at comparable solids contents). The solution polymer decreases the static surface tension of the inks, but generally leads to an increase in their equilibrium drop contact angle oil the polyethylene- (PE-) coated board due to increase in the ink-board interfacial energy. The solution polymer also decreases the drop spreading rate, and a simple model is tested to express the spreading dynamics in terms of equilibrium contact angle and a rate parameter given by the effective ratio of surface tension to viscosity.
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| 2. |
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| 3. |
- Corkery, Robert W, 1967-, et al.
(författare)
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On the formation and structure of nanometric polyhedral foams : toward the dry limit
- 2008
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:18, s. 10443-10452
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Tidskriftsartikel (refereegranskat)abstract
- High surface area, high porosity, nanometric polygonal silica foams with hierarchically connected and uniformly sized pore systems are reported here. We observe a remarkable increase in foam cell sizes from mesoscopic to macroscopic dimensions upon swelling the self-assembled template with oil. The resultant structures resemble classical macroscopic soap foams and display, among other features, Plateau borders and volume fractions approaching the dry limit of 100%. In well-developed foams of this kind, dimensionally isometric polyhedral cells are connected by relatively short, flat cylindrical mesopores through polyhedral faces and micropores through the walls. For one sample, with approximately 75 nm diameter primary foam cells, we infer three separate sets of cell-connecting mesopores puncturing tetragonal, pentagonal, and hexagonal faces of the component polyhedra. A multiple step model of foam formation is discussed where an organic silica precursor progressively hydrolyzes and condenses as a growing flexible shell from the core-corona interface of oil-swollen triblock copolymer micelles or microemulsion droplets, inducing a clouding phenomena in the otherwise stabilizing poly(ethylene oxide) chains, leading to aggregation, deformation, and jamming to high volume fractions.
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| 4. |
- Fogden, Andrew, et al.
(författare)
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An aqueous dispersion, a coated subject and use of an aqueous dispersion
- 2007
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Patent (populärvet., debatt m.m.)abstract
- There is disclosed an aqueous dispersion comprising a) inorganic particles b) at least one fatty acid or a salt thereof, c) a polymeric binder, and d) water, wherein said aqueous dispersion is free of organic solvent. There is also disclosed use of an aqueous dispersion comprising a) inorganic particles, b) at least one fatty acid or a salt thereof, c) a polymeric binder, and d) water, as a coating on a substrate surface, wherein said surface after coating displays an equilibrium contact angle higher than 120° degrees, preferably more than 135°, most preferably more than 150° for a drop of water on the surface. There is also disclosed a method for coating a substrate comprising contacting said substrate with the aqueous dispersion. The coating allows application in one step, it is non-toxic, safe for food packaging, and environmentally friendly as well as inexpensive.
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| 5. |
- Fogden, Andrew, et al.
(författare)
-
An aqueous hydrophobic coating composition comprising a fatty acid or a salt thereof
- 2007
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Patent (populärvet., debatt m.m.)abstract
- There is disclosed an aqueous dispersion to be used in the manufacture of a hydrophobic coating, wherein said aqueous dispersion comprises: inorganic particles, at least one fatty acid or a salt thereof, a polymeric binder, and water. There is further disclosed a method for preparing an aqueous dispersion and a method of coating a substrate. There is also disclosed a subject coated with the method. The coating can be applied in one step, it is non-toxic, safe for food packaging, and relatively environmentally friendly as well as inexpensive.
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| 6. |
- Fogden, Andrew, et al.
(författare)
-
Fokus på ytan
- 2004
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Ingår i: SPCI Sv. Papperstidning nr 12/2004.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 7. |
- Kipkemboi, Pius, et al.
(författare)
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Triblock copolymers as templates in mesoporous silica formation : Structural dependence on polymer chain length and synthesis temperature
- 2001
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 17:17, s. 5398-5402
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous silica can be formed with amphiphilic molecules acting as structure-directing templates in dilute systems. The templating properties of five related triblock copolymers, (EO)x-(PO)y-(EO)x (Pluronic L101, P103, P104, P105, and F108), have been investigated regarding the length of the EO blocks as well as the temperature of the synthesis. It was found that the number of EO units is essential in determining which silica mesophase is obtained. Lamellar structure is obtained with short EO chains (4 units); hexagonal structure, with medium length EO chains (17-37 units); and cubic structure, with long EO chains (132 units). The hydrophobicity of the (EO)x-(PO)y-(EO)x polymer is strongly affected by the temperature. This is to some extent reflected in the silica mesostructure formed; a multilamellar vesicle morphology can be obtained at elevated synthesis temperatures. Also, the temperature has an influence on particle size.
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| 8. |
- Pettersson, Torbjörn, et al.
(författare)
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Analysis of spreading of individual toner particles and levelling of toner layers
- 2004
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Ingår i: IS&T'S NIP20. - : The Society for Imaging Science and Technology. ; , s. 88-93
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Konferensbidrag (refereegranskat)abstract
- In the fusing of electrophotographic prints, the spreading and coalescence of individual toner particles and levelling of films are driven by surface tension and determine the optical parameters of dot gain and gloss as well as print adhesion. In this study a laboratory method has been developed to monitor in-situ the spreading of individual toner particles during heating, and extract the corresponding evolution in particle diameter and contact angle. This method was employed to study different toner particles as a function of temperature, heating rate, and substrate surface energy. Significant differences in spreading extent and rate for the different toner particles were observed, especially on higher energy surfaces, and explained in terms of their dispersive and polar interactions. This study was combined with Xeikon printing trials using systematic variations in the fusing type and degree. The prints were analysed with interferometric profilometry to quantify the response of toner layer thickness and surface topography to the fusing conditions. In particular, spectral decomposition of surface roughness revealed interesting correlations to print gloss.
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| 9. |
- Rentzhog, Maria, et al.
(författare)
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Correlations between properties of water-based flexographic inks and their print uniformity on PE-coated board
- 2006
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 21:3, s. 403-410
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Tidskriftsartikel (refereegranskat)abstract
- Uniformity of fulltone flexographic prints on PE-coated board was investigated for a large matrix of aqueous inks with varying acrylic-based vehicles and pigment concentrations, and with their applied amounts varied using a wide range of anilox volumes. Print mottle was characterised by coefficient of variation of reflectance, and partitioned into different feature-size classes. For all prints the mottle was caused by the residual pattern of white (poorly-covered) stripes originating from the anilox ruling, and subsequently distorted and redistributed to both finer and coarser length scales during transfer to, and flow on, the print substrate. Accordingly, mottle was largest on the sub-millimetre scales encompassing these stripe features, and generally increased with anilox volume, approximately proportionally so on above-millimetre scales. While greater pigmentation naturally increased both print density and mottle, the vehicle also exerted a strong influence, with mottle decreasing with increased content of soluble (versus emulsion) polymers. The latter was principally due to the associated increase in low-shear viscosity and decreased surface tension, both serving to reduce substrate dewetting. Empirical relations accurately correlating mottle to these two ink properties, and anilox volume and print density, were established.
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| 10. |
- Rentzhog, Maria, et al.
(författare)
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Effect of corona treatment of PE-coated board on water-based flexographic print resistance
- 2006
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 21:2, s. 202-210
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Tidskriftsartikel (refereegranskat)abstract
- The effect of corona treatment of Polyethylene-(PE-) coated liquid packaging board on its surface chemistry was quantified using surface energy determination by drop spreading and dyne-liquids, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The increase in total surface energy, due to its polar component, with increasing corona dosage, and its decrease on aging and washing, was strongly correlated to surface oxidation fraction from XPS. A fine structure of nano-mounds formed by oxidised material was revealed by AFM, with size and substrate coverage increasing with corona dosage, but no longer visible after washing. Resistance properties of water-based flexographic prints on these treated PE substrates were tested, with only wet rub resistance exhibiting a significant dependence on corona dosage. This property first increased at lower dosages before decreasing at higher levels, presumably due to worsened water resistance from soluble oxidised material dissolved in the ink film.
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| 11. |
- Rentzhog, Maria, et al.
(författare)
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Influence of formulation and properties of water-based flexographic inks on printing performance for PE-coated board
- 2005
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 20:4, s. 410-417
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Tidskriftsartikel (refereegranskat)abstract
- In this study the flexographic printing of lowdensity polyethylene- (LDPE-) coated liquid packaging board is analysed for a range of water-based inks, varying in type of pigment and acrylate-polymer vehicle and pigment/vehicle mixing proportions. One vehicle is solely based on emulsion polymer, another contains solution polymer, and the third is a 50150 blend of these two. Vehicle type and relative amount are shown to have a strong and systematic bearing on the absolute amount of ink transferred and its corresponding print density, gloss, and uniformity. For both ink colours (cyan and black), transferred amount increases with pigment content and is highest for the 50150 intermediate vehicle. Print density and homogeneity are generally highest for the vehicle containing highest content of solution polymer, at least with the lower anilox volumes, and this vehicle also gives highest print gloss. The wet amount of ink transferred is shown to be well correlated to its surface tension and viscosity.
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| 12. |
- Rentzhog, Maria, et al.
(författare)
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Print quality and resistance for water-based flexography on polymer-coated boards: Dependence on ink formulation and substrate pretreatment
- 2006
-
Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 57:3, s. 183-194
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Tidskriftsartikel (refereegranskat)abstract
- The performance of water-based acrylic flexographic inks laboratory printed on three different polymer-coated boards, namely coated with LDPE, OPP and PP, have been analysed and interpreted. The print quality and resistance properties obtained were related to varying ink formulation, in particular choice of emulsion polymer and presence of silicone additive in the vehicle, as well as varying levels of corona pretreatment. Print mottle and adhesion were worst on PP, while wet (water) rub and scratch resistance were worst on OPP and PE, respectively. However, these properties could be greatly influenced by the ink formulation, more so than corona level. In general addition of silicone improved scratch resistance, due to reduction in polar energy component of the print surface, but at the expense of worsened wet rub resistance. The emulsion polymer giving best resistance performance was generally found to give poorest optical properties, presumably due to more limited resolubility on press.
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| 13. |
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| 14. |
- Voltaire, Joakim, et al.
(författare)
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Acoustic characterisation of film splitting in a HSWO printing nip
- 2007
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 22:4, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- An acoustic technique for investigation of ink film splitting was further developed and applied to monitor printing of light weight coated (LWC) papers on a heat-set web offset (HSWO) press. The acoustic average power from the nip exit was found to decrease with decreasing ink amount and ink tack and increasing fountain solution amount. When printing on the lower side, the average power increased with surface pore area of the LWC papers, presumably connected to tack build during the extended contact time with the blanket. The method is non-destructive, statistical, and readily automatable, with applications both as on-line sensor and research tool for probing dynamic interactions during ink transfer.
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| 15. |
- Voltaire, Joakim, et al.
(författare)
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Acoustic emission and tack of heat-set inks during setting on MWCpapers and fountain solution emulsification
- 2007
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 22:4, s. 432-440
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the relationship between ink film splitting noise and ink tack, two tack-measuring devices were monitored by a microphone. The first of these was the Deltack(R) (Prufbau), to study tack build on paper, and the second was the Hydroscope(R) (Testprint), measuring ink tack change with fountain solution level. Three medium weight coated (MWC) papers and two heat-set inks of differing tack and emulsion capacity were analysed. It was concluded that acoustic average power is a consequence of cavitation and flow mechanisms, and not necessarily linked linearly to tack. The Hydroscope measurements usually gave decreasing tack, average power and average frequency with increasing fountain solution concentration; however fountain solution droplets can also act as an extra sound source. A relation between average frequency and droplet size was postulated. The results demonstrate the sensitivity of the acoustic method and support its implementation for further studies in the field.
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| 16. |
- Voltaire, Joakim, et al.
(författare)
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Acoustic investigation of cavitation noise from offset ink film splitting
- 2006
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 21:3, s. 314-322
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Tidskriftsartikel (refereegranskat)abstract
- The acoustic signal from the nip during film splitting between inked rollers and on ink transfer to paper was investigated on laboratory scale, using two sheet-fed offset inks (based on mineral oil and vegetable oil) and two coated fine papers (glossy and matte). Film splitting emits a broad noise-like acoustic spectrum in the range 5-50 kHz, from which the two simplest measures of average power and average frequency were derived. Using these two measures, four characteristic regimes of film splitting on the rollers could be distinguished as a function of ink load. Moreover, for intermediate amounts, average power was found to be accurately predicted by a simplistic model of sound produced by cavity expansion due to the under-pressure in the nip exit, thus providing a physical interpretation of the nip noise emission. For printing, the average power was higher for the glossy paper than the matte, presumably due to a more efficient sealing of the nip, or onset of ink setting. The vegetable oil-based ink gave higher power than its mineral oil counterpart. These results were found to be consistent with longer-time measurements of tack evolution from the Ink Surface Interaction Tester. This correlation and the verified theory thus provide support to practical applications of acoustic emission as an on-press monitoring tool.
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| 17. |
- Voltaire, Joakim, et al.
(författare)
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New technique for monitoring ink-water balance on an offset press
- 2007
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Ingår i: Appita journal. - 1038-6807. ; 60:2, s. 120-128
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Tidskriftsartikel (refereegranskat)abstract
- An acoustic technique, with microphone placed near the print nip exit on a. sheet-fed offset press during trial printing of newsprint, was used to provide information relating to splitting of the ink-fountain solution film. The average acoustic power increased with tack of the ink used and with target optical density. Further, average power decreased during each run, reasonably strongly correlated to increase in fountain solution consumption. This indicates that average power is primarily sensitive to instantaneous tack of the ink-fountain solution film, and can be used to monitor tack and indirectly infer ink-water balance in the nip. Laboratory experiments were also performed using the Hydroscope instrument to simultaneously measure tack and average acoustic power of the splitting of inked rollers during fountain solution titration and evaporation. While these two measured parameters were not directly correlated over all conditions of emulsification, both decreased in tandem over intermediate amounts of fountain solution.
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| 18. |
- Voltaire, Joakim, et al.
(författare)
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Use of an on-press acoustic sensor to monitor coldset offset printing of newspaper
- 2006
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 21:3, s. 323-327
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Tidskriftsartikel (refereegranskat)abstract
- A newly developed acoustic emission on-line monitoring technique (Voltaire J. et al. 2004) provides insight into the dynamic interactions occurring between paper, ink-fount emulsion, and rubber blanket in offset printing. The technique uses a microphone placed in the vicinity of the exit of the paper-blanket nip. Through digital signal processing of the measured sound pressure it is possible to distinguish between machinery sound and that caused by the tacky ink splitting. In this study, printing of coldset inks on newsprint was carried out on a two-unit sheet-fed offset press. In line with earlier results, an increase in print density was found to correspond to increased sound pressure at the nip exit for higher frequencies (above 15 kHz). Depending on the status of the press at start-up, i.e. ink and fount condition and temperature, an increase or decrease towards a more stable value of the sound pressure was detected during the early running of the press, and in both cases this correlated well with the evolution in print density to its target value. This and related results can prove useful for monitoring, and adjusting by feedback, the initial press equilibration before the print-ready stage. Moreover, the acoustic emission can directly reveal destabilised conditions at longer running times that by other means would not be detected until later.
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| 19. |
- Vyorkka, Jouko, et al.
(författare)
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Hydrophobic Coatings
- 2007
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Patent (populärvet., debatt m.m.)abstract
- A process for improving the hydrophobicity of architectural coating compositions and adhesive release surface compositions, the process comprising preparing at least one of said compositions using the following components: inorganic particles, at least one fatty acid or a salt thereof, a polymeric binder, and water. There is further disclosed a method for preparing an aqueous composition and a method of coating a substrate.
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| 20. |
- Wang, Ying, et al.
(författare)
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Mesh phases in a ternary nonionic surfactant, oil, and water system
- 2006
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:26, s. 10951-10957
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Tidskriftsartikel (refereegranskat)abstract
- The binary system of hexaethylene glycol n-hexadecyl ether (C16EO6) and water ((H2O)-H-2) has a complex, temperature-dependent lyotropic phase sequence, in the concentration region of 48-62 wt %. On cooling it shows the sequence lamellar phase, L-alpha, random mesh phase Mh(1)(0), rhombohedral mesh phase, Mh(R (3) over bar hm), bicontinuous cubic phase, V-1(Ia (3) over bar hd), and a two-phase hexagonal region, H-1 + L-beta. On heating from the latter two- phase region the phase sequence is V-1(Ia (3) over bar hd), Mh(1)(0), and L alpha. Polarizing optical microscopy, H-2 nuclear magnetic resonance, and small-angle X-ray scattering have been used to study the stability of these phases, their sequence, and their physical parameters with the addition of the oils, 1-hexene, decane, and octadecane. The oils are located within the alkyl chain regions of the mesophase structures. Depending on whether the added oil is "penetrating" or "swelling", it may reside in the region between the C-16 alkyl chains of the surfactant or at the center of the bilayer and affect phase stability. Oils affect both the volume of the alkyl chain region (at fixed surfactant water mole ratio) and the rigidity of the interfacial region. Both effects can influence the phase structures and their ranges of stability. Adding different types of oil to the mesh phases gives an opportunity to understand the factors that are important in their formation. The transition from the Mh(1)(R (3) over barm) phase to Mh(1)(0) phase is triggered by the hydrocarbon region swelling to a critical volume fraction of 0.32, a surfactant rod radius of similar to 1.75 nm, and a critical water layer thickness of similar to 2.5 nm. The latter is most likely responsible for a weakening of the interlayer headgroup overlap interaction and the loss of correlation between the layers. The lamellar phase becomes the only stable phase at high oil content.
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| 21. |
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