• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.61-67
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• 2016

This study was carried out in order to investigate the effect of pigment properties in a pre-coating layer on the characteristics of a top-coating layer and the print mottle of the coated paper. Five different pigments were applied for this study as raw materials for the pre-coating layer. The properties and print mottle of the coated paper samples were evaluated according to the coating color formulation. Type of pigments appliied in a pre-coating layer was one of the most important factor to control the properties of pre and top coating layer. Surface properties of pre and top coated paper were improved by blending GCC which had smaller particle size, with clay. Properties of a top-coating layer was affected by the pigment properties used in the pre-coating layer. It was found that print mottle of coated paper can be improved by replacing part of GCC with smaller particle size GCC or clay in pre-coating layer.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.62-73
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• 1998

The aim of this work was to investigate the effects of pigment composition on the calendering response and structure of the coated paper. Calendering response of the coated paper was determined from the gloss values of the uncalendered and calendered coated papers, and the relationship between gloss and coating structure was discussed. The surface and cross section of the coating layer was observed using a scanning electron microscope to examine the coating structure. Coating layers were hardened in epoxy resin and polished with carbimet paper disc for preparing SEM samples. Maximum calendering response was obtained for the coated paper prepared from 80pph of clay and 20pph of ground calcium carbonate (GCC) as pigments. Photomicrographs of the surface and cross section of the coating layer show that clay tends to form dense coating structure, while GCC tends to form bulky coating layer.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.4
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• pp.79-84
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• 1998

The process of double coating consists of bottom coating using relatively coaser pigments to improve characteristics of base paper and top coating using finer pigments to cover unevenness of the bottom coating and to give various function of the coated paper. The structure of precoating is influenced not only by its components, but also characteristics of base paper, Moreover pore size and its size distribution of precoating are expected to influence the top coating properties, but this is not well understood. Coating and printing operations involve the application of pigmented fluid on top of a porous substrate. The porosity of the substrate has been shown to influence the properties of the coating, but a good understanding of the mechanisms is lacking in the literature. The role of pore size and void volume on top coating structure is unclear.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.5
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• pp.39-45
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• 2012

For a fundamental study for high concentration pigment coating, the effects of alkali swellable emulsion (ASE) type rheology modifier and surface adsorption emulsion (SAE) type rheology modifier on both the stability and the viscoelastic behavior of a coating color were elucidated. The coating color prepared with SAE type rheology modifier showed superior thermal and mechanical stability than that with ASE type. In the high concentration and high speed coating process, the mechanical stability of a coating color was a key parameter since both impact force and shear force were increased with the increase of coating color concentration and coating speed, respectively.

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.2
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• pp.25-40
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• 1997

This research was carried out to investigated the effect of base paper and latex binder on printability and obtical properties of coated paper. Especially, it examined the effect of th pH of vase paper surface and functional groups of latices on the interactions between coating color components and on the structure of coated layer. It was found that the behavior of coating color containing amphoeric latex depends on the pH in the boundary region between coating color and base paper. Thus, the coating color formulated with amphoteric latex formed bulky coating layer by inducing stronger interaction between paper surface and coating components than the coating color with anionic latex. The coated paper with amphoteric latex showed better optical properties (i.e.gloss and optical) and printability (i.e. ink receptivity, wet ink receptivity, and ink set off) than the conventional anionic latex in the acidic and alkaline paper. However, dry pick strength of the coated paper was less decreased. This result indicated that amphoteric latex could also be applied practically to the alkaline paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.3
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• pp.41-51
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• 2007

In order to elucidate the effects of types and mixing ratio of GCC and clay, coating color concentration, and types of rheology modifiers on high solid coating, various coating colors were prepared, high shear viscosity was measured and then rheology of the coating colors was analyzed. Coating color concentration was able to be increased from 67% to 69% and from 68% to 71% with a higher GCC ratio and with the rheology modifier instead of the synthetic thickener, keeping similar or improved coating color rheology and coated paper quality. The rheological properties of high solid coating color were superior with smaller average particle sizes of clay and latex, wider size distribution of GCC and higher added amount of latex.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.57-64
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• 1999

This research was carried out to investigate the effects of density, resin and particle types on the physical and mechanical properties of the composites made from various wood particles mixed with coating paper. The experiment was designed to apply with three particles (flake, chip, and fiber) and three resin types (urea, phenol and PMDI resin). The mixed ratio of coating paper to wood particle was fixed on 50 to 50% in each board making. And also it was designed to apply for four density levels (0.6, 0.7, 0.8 and 0.9 g/$cm^3$) and four mixed formulations of coating paper to wood particle (10:90, 20:80, 30:70, and 40:60 %) to analyze clearly the effects of PMDI resin. Coating paper-wood particle composites have acceptable bending strength (MOR, MOE) though the mixed ratio of coating paper was increased, but have low internal bond strength and poor dimensional stability (WA, TS, LE). Composites with high density had higher mechanical properties but showed lower physical properties than composites with low density. In conclusion, at least up to 20% mixed ratios, coating paper-wood particle composites have acceptable physical and mechanical properties, and PMDI resin has possibility for coating paper-wood particle composite manufacture.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.4
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• pp.16-22
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• 1999

The quantitative analysis of SB latex contents in coating color and coated paper was investigated with FT/Raman spectroscopy. From the measured FT/IR and FT/Ramon spectra, the peaks of coating color were compared with those of each compoents . Calibration curves were obtained by the area of latex peaks and PLS method of QuantIR program. The relation of predicted values in PLS method and actual values in coating mixtures and coating layer was examined. The components of coating layer in coated paper were investigated by EDS , X-mapping and SEM, The contents of latex in z-direction were calculated in the coating layer of unknown coated paper. The latex concentration measurements of Top layer and Pre layer in double coated paper show that each layer has different value. In single coated paper, it is clear that the latex concentration is highest at the surface and decreases with an increase of depth. From those results it is indicated that the latex migrates to the coated surface. The result of this study may be applied to the binder migration study and the quality control in paper mill.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.134-140
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• 2015

This study was carried out to evaluate whether EVAc, acryl latex and biobinder could substitute the part of SB latex for pre-coating color formula or not. Different coating colors prepared through the substitution of 30% SB latex with EVAc, acryl latex, and biobinder were applied for pre-coating layer. 100% SB latex is used as a binder for top coating color. The optical properties, gloss, roughness, stiffness, dry- and wet-pick strength were measured. There were no significant differences in the brightness, whiteness, opacity, roughness, ink set-off and gloss of paper coated with 5 different coating colors. However the stiffness, dry- and wet-pick strength were somewhat lower than those of conventional coating color which 100% SB latex was used as a binder. Although the part of SB latex could be substituted with EVAc, acryl latex and biobinder without sacrificing the qualities of coated paper. Further researches on the improvement of stiffness, dry- and wet-pick strength, and the optimization of rheology of coating color in order to improve the qualities of coated paper are strongly recommended.

• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.10-16
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• 1997

This study was carried out to improve coating structure by controlling the electrostatic interaction of coating components and by changing the coating structure of coated paper prepared with amphoteric and anionic latices. The results indicated that amphoteric latex copolymerized with carboxylic and amine groups had stronger interaction with other coating components than anionic latex with branched carboxylic group by controlling pH. These properties of amphoteric latex showed positive effects on viscosity rheology, and supernatant sediment of coating color. The coated paper using amphoteric latex had also produced more porous and smoother coverage of the coating layer than that using anionic latex. This porous and smooth coating layer showed better optical properties and printability than those of anionic latex such as opacity, porosity, ink set-off, and wet ink receptivity.