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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korea Technical Association of The Pulp and Paper Industry
Journal Basic Information
Journal DOI :
Korea Technical Association of the Pulp and Paper Industry
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Volume & Issues
Volume 34, Issue 5 - Dec 2002
Volume 34, Issue 4 - Dec 2002
Volume 34, Issue 3 - Oct 2002
Volume 34, Issue 2 - Jun 2002
Volume 34, Issue 1 - Apr 2002
Selecting the target year
The Critical Pigment Volume Concentration Concept for Paper Coatings: I. Model Coating Systems Using Plastic Pigments and Latex Binders for Paper Coating Applications
Lee, Do-Ik ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 1~17
The immobilization and consolidation of the model coatings based on the plastic pigment and latex binder of known particle sizes were theoretically Studied in terms of the dense random packing of binary spheres and varying extent of latex film shrinkage. The porosity of the model coatings was calculated based on three proposed latex shrinkage models: Maximum, Minimum, and Linearly Decreasing Latex Shrinkage. The increasing extent of latex shrinkage was calculated up to the critical pigment volume concentration(CPVC) as a function of plastic pigment volume fractions, and the maximum latex shrinkage was estimated from the CPVC. Also, the number of pores and the average equivalent spherical pore diameters were calculated based on those proposed models. The opacity and gloss of the model coatings on polyester films were measured and their porosity was also determined by a simple coat weight-thickness method. As expected, various coating structure-property-composition relationships, such as opacity, gloss, porosity, etc., were shown to exhibit sharp transitions near the CPVC. The CPVC values determined by the opacity, gloss, and porosity vs. PVC relationships, respectively, agreed very well with each other. Especially, the CPVC's determined by the opacity and porosity vs. PVC curves were identical. The comparison between the theoretically calculated and experimental porosity values showed that the intermediate value between the maximum and minimum latex shrinkage would best fit the experimental porosity data. The effect of plastic pigment particle size on the optical properties and porosity of model coatings was also studied and it was observed that the coating opacity and porosity increased with increasing plastic pigment particle size, but the gloss decreased. The ink gloss of the uncalendered model coatings applied onto commercial sheet offset coated papers was shown to be affected by both the coating gloss and porosity: the higher the coating gloss, the higher the ink gloss, but the higher the coating porosity, the lower the ink gloss. Their printability was also studied in terms of the number of passes-to-fail and the rate of ink setting as a function of both plastic pigment volume fractions and plastic pigment particle sizes. A minimum crack-free temperature(MCR) of latex-bound coatings was proposed to better predict the behaviors of latexes as coating binders. The wet state of model coating dispersions, the surfaces of consolidated model coatings, and their internal structure were examined by both electron and atomic force microscopy, and their micrographs were found to be consistent with our immobilization and consolidation models.
The Critical Pigment Volume Concentration Concept for Paper Coatings: II. Later-Bound Clay; Ground Calcium Carbonate, and Clay- carbonate Pigment Coatings
Lee, Do-Ik ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 18~38
A previous study on the model coatings based on latex-bound plastic pigment coatings (1) has been extended to latex-bound No. 1 clay, ultra-fine ground calcium carbonate (UFGCC), and clay-carbonate pigment mixture coatings, which are being widely used in the paper industry. The latex binder used was a good film-forming, monodisperse S/B latex or 0.15
. No. 1 clay was representative of plate-like pigment particles, whereas UFGCC was of somewhat rounded rhombohedral pigment particlel. Both of them had negatively skewed triangular particle size distributions having the mean particle suet of 0.7
, respectively. Their packing volumes were found to be 62.5% and 657%, respectively. while their critical pigment volume concentrations (CPVC's) were determined to be 52.7% and 50.5% ( average of 45% caused by the incompatibility and 55.9% extrapolated) by coating porosity, respectively. Each pigment/latex coating system has shown its unique relationship between coating properties and pigment concentrations, especially above its CPVC. Notably, the clay/latex coating system hat shown higher coating porosity than the UFGCC/latex system at high pigment concentrations above their respective CPVC's. It was also found that their coating porosity and gloss were inter-related to each other above the CPVC's, as predicted by the theory. More interestingly, the blends of these two pigments have shown unique rheological and coating properties which may explain why such pigment blends are widely used in the industry. These findings have suggested that the unique structure of clay coatings and the unique high-shear rheology of ground calcium carbonate coatings can be judiciously combined to achieve superior coatings. Importantly, the low-shear viscosity of the blends was indicative of their unique packing and coating structure, whereas their high-shear rheology was represented by a common mixing rule, i.e., a viscosity-averaging. Transmission and scanning electron and atomic force microscopes were used to probe the state of pigment / latex dispersions, coating surfaces, freeze fractured coating cross-sections, and coating surface topography. These microscopic studies complemented the above observations. In addition, the ratio, R, of CPVC/(Pigment Packing Volume) has been proposed as a measure of the binder efficiency for a given pigment or pigment mixtures or as a measure of binder-pigment interactions. Also, a mathematical model has been proposed to estimate the packing volumes of clay and ground calcium carbonate pigments with their respective particle size distributions. As well known in the particle packing, the narrower the particle size distributions, the lower the packing volumes and the greater the coating porosity, regardless of particle shapes.
A Simple Method for Measuring the Immobilization Solids of Coating Colors Using an AA-CWR Water Retention Meter
Park, Chang-hak ; Lee, Do-Ik ; Margaret K. Joyce ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 39~48
The water retention of coating colors can be accurately measured by devices such as an AA-GWR water retention meter whose principle of measurement Is based on pressure filtration of coatings under an externally applied air pressure over a certain period of time. It was hypothesized that such devices could be also used to determine the immobilization solids (IMS) of coating colors by determining a sudden drop in the rate of dewatering, that is, a sudden change in the drainage curves. To test this hypothesis, the immobilization solids of coating colors containing various thickeners and water retention additives at different levels were first accurately measured by a modified immobilization tester based on the well-known gloss drop method, and then their values were compared with those obtained by an AA-GWR water retention tester. They agreed very well and showed that the standard deviation is only 0.14% in the IMS points between both methods. This good agreement was not surprising because both test methods are based on the same end-point, that is, the immobilization solids point at which menisci begin to form at the coating surface. Theoretical considerations supporting this new method for measuring the immobilization solids of coating colors are presented and some recommendations for the test method are discussed. Also, the effect of various thickeners and water retention additives on the properties and printability of coated papers is discussed.
Development of a New On-line fiber Orientation Sensor Based on Dielectric Anisotropy
Nagata, Shinichi ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 49~55
A new method is proposed for the on-line measurement of the fiber orientation of sheet materials. The measurement of fiber orientation is very important in manufacturing paper sheets, non-woven fabrics, and glass sheets, because fiber orientation strongly affects product properties represented by, for example, dimensional stability of paper. A method developed in this research utilizes anisotropy of dielectric constants of sheet materials as a key characteristic to determine the fiber orientation. The new on-line sensor, consisting of 5 microwave dielectric resonators set in different directions, was designed to detect the fiber orientation while paper is running with high speed on a paper machine. This sensor can determine the direction and the degree of fiber orientation from the measured direction of the maximal dielectric constant and its variation, respectively. The fundamental performance of this system was examined by the static measurement of printing grade paper, which gave a satisfactory result. Then, the dynamic measurements were done at a speed of 1,000 m/min by using a high-speed test-coating machine.
Mechanical Impact Treatment on Pulp fibers and Their Handsheet Properties
Yung B. Seo ; Kim, Dukki ; Lee, Jong-Hoon ; Yang Jeon ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 56~62
Alternative way of shaping fibers suitable for papermaking was introduced. Impact refining, which was done simply by hitting wet fibers with a metal weight vertically, was intended to keep the fibers from shortening and to cause mostly internal fibrillation. Virgin chemical pulp, its recycled one and OCC were used in the experiment. It was noticed from the experiment that impact refining on virgin chemical pulp kept the fiber length and increased bonding properties greatly. However, in the recycled fibers from the chemical pulp, fiber length and bonding properties were decreased. In OCC, which seems to contain fractions of semi-chemical pulp and mechanical pulp (GP), and which is recycled pulp from corrugated boxes, fiber length and bonding properties were decreased disastrously. We believe recycled cellulosic fibers (recycled chemical pulp and OCC in this case), which went through hornification, were less resistant to the mechanical impact than virgin chemical pulp. For virgin chemical pulp, impact refining allowed no significant fiber length shortening, high WRV, and high mechanical strength.
New Concept of Stiffness Improvement in Paper and Board
Seo, Yung B. ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 63~69
A new concept of stock preparation for the increase of bending stiffness in paper and board was proposed. The "stiff" fibers, which were mechanically not treated or treated slightly to remove fiber curls, were combined with extensively refined fibers (ERF) to produce higher stiffness papers than those where the whole fibers were refined. The combination of "stiff" fibers and extensively refined fibers produced higher stiffness at the same tensile strength than the control furnish, in which all the fibers are refined together. In this concept, the fibers from recycled papers could be as much useful as the virgin fibers as long as they are stiff enough or they can produce highly bondable fiber fractions by extensive refining. Use of the concept in real paper mill needs considerations such as increase of refining energy, slower drainage, and added drying burden, but savings of wood fibers, utilization of more recycled fibers, and increase of physical properties may offset the negative concerns. The success of this concept implementation in mills, therefore, depends on the wood fiber market around the mills and the proper decision making for the papermakers about how to apply this concept. apply this concept.
Experience of Seventeen Compact Wet End Systems
Meinander, Paul-Olof ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 70~76
Ten years ago most papermakers were convinced that a system needs to be voluminous and heavy for controllability and stability. In order to improve grade changing dynamics, the author of this paper began developing a compact papermachine wet end. The results have proven that compactness is beneficial even more broadly. Quoting Voith
the trend is now the opposite - the systematic collecting and direct feeding of the individual water flows back into the system". In its gasless form this is actually covered by a POM Technology Patent.tent.
Recent Developments in Kaolin-Based Paper Coating Pigments : Innovating to Meet Changing Industry Needs
Johns, Ronald E. ; Moore, John L. ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 77~85
Kaolin has long been used in aqueous coatings to produce high-quality coated paper products. While the kaolin industry hat always focused on innovation. the rate of new product introduction hat never been greater than in the past five-to-eight years due to the cost, quality and other competitive pressure facing papermakers. After summarizing many of the performance benefits offered by the new generation of kaolin-baled pigments. this paper reviews four specific pigment advances: a high-performance. ultrafine glossing pigment; an engineered pigment with a narrow particle size distribution; two products from a kaolin-based pigment family developed for metered size presses ; and a novel class of inkjet pigments.
A Summary of Recent Pilot Machine and Commercial Machine Trials Comparing a New Microparticle Retention System with Existing Microparticle Technologies
Johnson, Gray ; Gerli, Alessandra ;
Journal of Korea Technical Association of The Pulp and Paper Industry, volume 34, issue 5, 2002, Pages 86~92
The benefits of high performance retention systems have been long recognized by the paper maker. The inter-relation between chemical retention and drainage and their effect on paper production efficiency and paper quality is significant. The subject of this paper is a summary of recent studies comparing three microparticle programs made under highly controlled pilot and commercial paper machine conditions. The results presented in this paper suggest that, in addition to improvements in machine operation, the retention, drainage and formation program can have a marked influence on the paper quality. Improvement of the topographical characteristics of the base paper was observed when the microparticle was a colloidal borosilicate inorganic oxide.