• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.5
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• pp.32-38
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• 2012

This study was carried out to elucidate the potential in substitution of SB latex with eco-friendly starch based bio-binder as a coating binder. The part of SB latex in coating color of pre- and top layer was substituted with starch based bio-binder in order to evaluate the characteristics of coating color and coated paper, and printability. The viscosity and water retention of coating color were increased by substitution of SB latex with starch based bio-binder. Roughness of coated paper was increased by substitution with starch based bio-binder, although there was not significant changes in roughness when SB latex is used as a binder in pre-coating color. Brightness and whiteness of coated paper were not affected, but opacity and print mottle were improved by substitution with starch based bio-binder. The interesting result observed was that dry-pick did not affected significantly, and ink set-off was improved by starch based bio-binder. It is expected that starch based bio-binder can be commercialized if the systematic further research works are carried out.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.4
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• pp.29-37
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• 2007

The effects of latex particle size, basis weight of base paper and coating color concentration on the printing quality of coated paper were investigated. Coating colors were prepared with five types of latexes having different particle sizes. Coated papers were produced with high solid coating colors and with low solid coating colors in a industrial coater, respectively. In high solid coating colors, rheology modifier was used and GCC content was high. It was concluded that, in order to control binder migration and hence print mottle, latex particle sizes shall be controlled as well as formation, sizing degree and roughness of basis paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.1-8
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• 2014

In this study, the influence of the physical properties of ink such as ink dispersity and emulsified amount on the printability of a coated paper was investigated with seven kinds of cyan inks. In addition, two kinds of coating formulations were tested to evaluate the effect of coating structure on the coated paper printability. It was found that the cyan ink with $2{\mu}m$ pigment size had the best dispersibility and hence the ink showed a best ink density on the two kinds of coated papers. When the emulsified ink A with IPA 20 wt% had a lower viscosity than emulsified ink B with IPA 10 wt%, the emulsified ink A showed relatively high value of the ink transfer rate in comparison with emulsified ink B. Despite the high value of ink transfer rate, the coated paper did not show a good printability because those inks with low viscosity due to a strong emulsification were easy to make print mottle on the coated paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.127-133
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• 2015

Recent worldwide trends are to develop the environmental friendly chemicals and processes in order to reduce the global warming and climate change phenomena. One of similar efforts in paper industry is to substitute the petroleum-based SBR latex by starch-based biobinder. The disadvantage of biobinder found through laboratory scale study was the lower dry pick strength than SBR latex. The objective of this study is to confirm the substitutability of SBR latex with biobinder through mill trial. Although biobinder itself gave lower dry pick strength, it was found that the use of SBR latex and biobinder mixture (50:50) could improve the dry pick strength. The introduction of biobinder into coating binder system improved the opacity of coated paper. Optical properties (brightness and whiteness), ink trapping, print gloss and mottling level of paper coated with biobinder system were similar to those of SBR latex.

• Journal of the Korean Graphic Arts Communication Society
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• v.24 no.1
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• pp.1-12
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• 2006

The rheological characteristics of an ink relate to its performance on the press and to the printing quality such as ink stability, transfer characteristics, mottle, squash, misting, dot gain, and so on. For lithographic print, the emulsification of ink is an important factor to determine the product. And also the rheological characteristics of the emulsified ink should be investigated. Thus, in this study, the effects of the changing molecular weight of rosin modified phenolic resin on the water-pickup ratio of neat inks were studied. And then rheological properties of neat inks and emulsified inks with changing molecular weight of rosin modified phenolic resin were analyzed by using rotational rheometer.

• 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.32 no.5
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• pp.60-66
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• 2000

Coating immobilization is the process by which the wet coating applied to paper or paperboard reaches the final form. A coating immobilization point is defined as the solids content reached during drying where no further redistribution of coating materials occurs. Good control of coating immobilization is important in producing coated paper and paperboard with consistent high quality. This paper discusses the technical concepts of how coatings immobilize, and describes the importance of good immobilization control on coating holdout and coating structure. The use of soy protein polymers to modify the coating immobilization point is discussed. Soy proteins, because of their interaction with coating pigments, make a significant contribution to the immobilization characteristics of coastings. This technology gives the formulator options for changing the immobilization point to improve the performance of the coating. The importance of immobilization on casting uniformity, microporosity and sheet qualities is discussed, including binder migration, mottle, gluing, and print quality.

• 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.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.63-70
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• 2014

Part of SB latex in pre-coating color was substituted with newly developed starch-based bio-binder in order to investigate the effect of starch-based bio-binder in pre-coating color on the properties of coating color and coated paper. Smoothness and gloss of coated paper were decreased with the increase of bio-binder substitution ratio. Brightness and whiteness did not show the significant changes, but stiffness was improved with bio-binder. Ink set-off, dry-pick and wet pick were decreased with the increase of bio-binder substitution ratio. In general, when all SB latex is substituted with bio-binder, ink set-off, dry- and wet-pick were deteriorated. However, it was found that if the bio-binder substitution ratio is controlled below 50%, similar qualities with coated paper manufactured by the use of SB latex binder can be obtained.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.3
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• pp.74-83
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• 1998

The phenomenon of decrease in sizing efficiency when the stock temperature is increased is well recognized as summer sizing, and this is believed to be caused by uneven distribution of sizing agents on paper surface most often incurred by coagulation of sizing agents. When unevenly sized paper is used as coating base stock, nonuniform consolidation of the coating layer may result, which, in turn, causes uneven distribution of binder on coating surface. This causes nonuniform ink absorption to produce print mottle. In this study the effects of simple or polymeric electrolytes, storage temperature and time on the coagulation of cationic dispersed rosin size were investigated using a turbidity measurement method which was verified to correlate well with the particle size of rosin emulsion or its coagulates. Handsheets sized with rosin dispersions coagulated under various conditions were prepared and their sizing degree and coated paper properties including gloss and ink density were examined. The relationship between the sizing nonuniformity of coated papers and its ink absorption property was evaluated. Turbidity of rosin emulsion increased as the storage temperature and time were increased. Addition of simple or polymeric electrolytes caused reduction in $zeta$ -potential of the rosin dispersion and accelerated the coagulation tendency substantially. Reversion of the $zeta$ -potential of rosin dispersion, however, did not occur when coagulation was induced with simple electrolytes. On the other hand, addition of an anionic polyelectrolyte reversed the $zeta$ -potential of the flocculated rosin dispersion. This indicated that electrical double layer compaction and bridging flocculation were coagulation mechanisms for simple and polymeric electrolytes, respectively. Sizing degree decreased as coagulation of rosin was increased. Paper gloss, ink gloss and ink density were increased when sizing degree of base stock was increased most probably due to prevention of base paper swelling and increased binder migration to coating surface. This suggested that uneven printing ink density occurred when uneven sizing development was induced by coagulation of rosin particles.