• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.04a
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• pp.54-69
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• 2003

Print gloss is an important attribute of the final printed product. While past work has looked at the influence of key aspects of the coating structure on print gloss, a systematic study has not been reported. The coating roughness, porosity, and pore size are changed by using various combinations of coating materials and by calendering against rough plastic sheets. The print gloss is measured every tenths of a second right after printing, a few minutes after printing, and a few days afterwards. Roughness and porosity affect the print gloss for the first two seconds: this result shows that they influence the ink-film splitting event. Once ink film starts to level, roughness and pore size influences the level of print gloss within the first ten seconds after printing. Porosity modifies the evolution of print gloss for the next few minutes. The decrease in gloss at long times is found to correlate to surface roughness.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.5
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• pp.26-43
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• 2000

It is well accepted that gloss variation deteriorates the print quality and there are various objective ways to measure this. Several studies now have shown that the coefficient of variation in the octave band passed printed gloss image has an excellent correlation with ratings by an expert panel using a magnitude estimation scaling method. The correlation improves when the gloss level is also taken into account beyond that of the COV. There is also evidence that the correlation would improve even more if the gloss spatial distribution could be better accounted for. We show that much (at least 80% and perhaps up to 90%) of the gloss distribution can be accounted for by the paper topography over a wide range of dimensions (scale). Recent work has supported the role that microroughness and multiple surface scattering play in the gloss distribution. This offers the promise of showing that even a greater amount of gloss variationcan be explained by topography.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.1
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• pp.22-29
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• 2002

The coated paper was greatly affected by the basic physical properties of the binder as well as the amount of the coating formula. High glass transition temperature (Tg) of the styrene-butadiene (SB) latex, selected as the binder in our study, gave the high stiffness to the coated paper, but lowered the binding force and print gloss. The average particle size of the SB latex also greatly affected to the coated paper so that the smaller particle size improved the rheological property of the coating formula and increased the binding force and print gloss. Another property of the SBR latex, gel content, was important because when its value was small, the latex was easily deformed at the high temperature and increased air permeability to the coated paper. Therefore, the lower gel content consequently resulted in the higher blistering resistance, especially in the web paper. The larger portion of the SB latex in the coated formula improved the binding force and print gloss, but decreased the ink set-off and ink-trapping to the coated paper. The heavier coating improved optical properties such as opacity, paper gloss and paper smoothness, to the coated paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.4
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• pp.16-21
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• 2002

It was observed that drying temperature and curing time in the paper coating process as well as Tg of the latex used as a binder, greatly affected the properties of the coated paper such as roughness, paper and print gloss, K & N ink drop, and ink set-off. The higher drying temperature induced faster water evaporation and change in binding density, which caused an increase in paper roughness, ink gloss and ink set-off, but decrease in paper gloss and K & N ink drop. The increased curing time promoted latex filming and redistribution of the binder in coating layer. This increased pick strength and ink gloss, but decreased ink trapping. Finally, the higher Tg of the latex showed the wider changing range of these properties.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.1
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• pp.26-35
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• 1997

A study was carried out to investigate such optical properties of coated papers as brightness, opacity and gloss affected by the coating pigment composition and coat weight using clay, ground calcium carbonate, precipitated calcium carbonate, and plastic pigment as pigments. The effects of drying methods and supercalendering on optical properties were also evaluated. Gloss increased abruptly while brightness and opacity decreased slightly by supercalendering due to surface smoothing and consolidating effects of the coating layers. Optical properties changed little by drying methods. Pigment composition showed significant influences on optical properties. Brightness of coated papers decreased or increased linearly as the coat weight was increased depending on the pigment composition, while opacity increased linearly for all formulations. Gloss increased abruptly at low coat weights for all formulations and approached a plateau value at coat weight of 15-20g/$m^2$. Third order polynomial regression equations relating the coat weight with gloss have been derived and tabulated.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.3
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• pp.53-58
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• 2002

This paper was performed to investigate the effect of pore structure on ink residual behavior. To prepare different coating structures as substrates against inks, fine, medium and coarse calcium carbonate were used in the coating color. It is well known ink properties can affect to print qualities. After printing on the coated paper, ink layer can consider as third structure addition to paper and coating layer. To compare effect of ink properties on the surface structure and print qualities, several properties of ink were also adopted as raw material. Particle size of pigment effect on gloss evaluation of coated paper increased with calendering. It was shown that ink transfer rate increased as surface of the sample was smooth. The ink contained low viscosity resin evaluated more print gloss. Finer pigment particle size, smaller pore size and higher porosity. Pore volume of coated paper was slightly decreased with printing as the coating was prepared with the finest particle size. However, it founded that ink resin could not affect on pore volume and distribution of printed paper

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.3
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• pp.56-62
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• 2012

Recycled pulp therefore play a very important role in the paper industry today as a substitute for virgin pulp. In many countries of the world, the paper industry could not exist as it does without recycled pulp. Because, this is mainly due to economic reasons. Particularly in our country, the additional reason is the scarcity of native pulpwood resources. Therefore, the use of recycled pulp is very important. This study was aimed to apply recycled pulp to textbook paper. So we made a paper containing 30% recycled pulp and investigated about print quality, such as color reproduction, trapping, contrast, dot gain, gloss and print through. The results showed that is similar to existing textbook papers.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.26-34
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• 2010

Effects of drying condition (IR radiation) on the optical properties and the printability of coated paper were elucidated at various latex sizes and low and high coating color concentrations. It was found that the smaller latex provided better rheology and higher dry and wet pick strength than the larger one. The high solids coating resulted in higher paper gloss and smaller roughness than the low solids coating, even though the clay addition was reduced by 20 parts in the high solids coating. Increasing IR radiation prohibited binder migration into the base paper. Thus it improved binder distribution and decreased pores in the coated layer, resulting in the increased dry and wet pick strength and the improved printing gloss. On the other hand, the color trapping and ink set-off was impaired with increasing IR radiation. Print mottle index passed through a maximum with increasing IR radiation.

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.1
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• pp.17-30
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• 1997

In this work, we have investigated the printability such as print through and str-off of domestic newspapers. Nine kinds of domestic newspapers Hansol, Deahan, Sinho, Hanla and Sepung, were tested by IGT printability tester, and studied using maximum ink requirement method. We obtained the datum of printability parameters such as maximum ink requirment of paper Ymax, printing density D, print through, set-off and gloss. The results of this test showed that a choice of the fillers on the newspaper had an effect on print through, set-off and density of newspapers in the maximum ink transfer point.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.10-16
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• 2015

Bio-binder is well known as a promising alternative binder for SB latex because it is eco-friendly and inexpensive, compared to synthetic latex. SB latex in top coating color was substituted with starch-based bio-binder to investigate its effects on the coating color and its coated paper properties. Bio-binder contributed to the increase of coating color viscosity, and the improvement of water retention. Most optical properties except opacity were deteriorated by the increase of bio-binder dosage. It was also found that the increase of bio-binder substitution in top coating color brought about the increase of roughness, and decrease of coated paper gloss, print gloss, dry and wet pick strength. However the stiffness and the ink set-off of the bio-binder coated paper were improved. Overall, mostly adverse effects of bio-binder on the properties of coating color and its paper were observed. Therefore, it is not recommended to use bio-binder as top coating color.