• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.3
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• pp.21-28
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• 2003

It is essential to use base papers having proper surface characteristics in coating operation for improving coated paper quality and coater runnability. To fulfill these purposes surface sizing of coating base stock with anionic oxidized starch is commonly practiced. It is suggested that use of cationic starch for surface sizing rather than conventional oxidized starch will improve coated paper quality since cationic starch penetrates less into paper structure because of its strong electrostatic interaction with anionically charged paper surface. Strong interaction of cationic surface sizing starch with anionic coating color is expected to promote rapid immobilization of the coating color and improve coating holdout and optical property. The immediate objective of this study was to examine the influence of surface sizing starches on the properties of coated papers. Structural characteristics of the coatings formed on the substrate surface sized with cationic and anionic starches were examined. To enhance the efficiency of cationic surface sizing starch on coated paper properties, strongly charged cationic polymers were added to the surface sizing starch and its effect on coated paper properties was evaluated. Results showed that opacity and light scattering coefficient of coated paper were higher when base paper surface sized with cationic starch was used. Addition of less than 1% of cationic poly-DADMAC to the cationic surface sizing starch improved the opacity of coated paper significantly.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.82-92
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• 2016

The reduction of carbon dioxide emission is hot issue in the world because we are confronted with serious global warming and climate change. As a part of carbon dioxide reduction efforts, various approaches for increasing filler loading have been carried out in order to decrease the energy consumption in papermaking processes. Effects of the pretreatment of GCC with cationic starch and MFC on the flocculation behaviour of GCC were investigated in this study. Pretreatment of GCC with cationic starch caused the change of electric charge of suspension and flocculation behaviour of GCC. Largest flocculation size was obtained near the isoelectric point in the case of cationic starch treatment. When MFC (30 times grinded) was added after preflocculation of GCC with cationic starch, the flocculation size was increased, but largest flocculation size was obtained at -150 mV of electric charge of suspension in this study. However the addition of highly grinded MFC (60 times grinded) caused smaller flocculation size of GCC than those of MFC (30 times grinded). When GCC and MFC were mixed first, and then cationic starch was added, the characteristics of MFC and the change of electric charge which could be brought by cationic starch did not affect the flocculation size of GCC at all. The flocculation size obtained by the combination of cationic starch and MFC was smaller than those of cationic starch. These results show that flocculation behaviour could be controlled by the change of electric charge of suspension and the combination methods of cationic starch and MFC.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.45-52
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• 1997

This study was carried out to investigate the adsorption characteristics of cationic starches onto BKP, BCTMP and talc. Concentration of the unadsorbed cationic starch contained in the supernatant of the pulp or talc slurries was determined using a spectoscopy method and the adsorption isotherm of cationc starch was constructed. When the equilibrium concentration of the cationic starch was low, almost complete adsorption of the starch onto BKP and BCTMP was observed. This indicates that electrostatic attraction is the main driving force for the adsorption of cationc starches onto pulps. BCTMP adsorbed greater amount of cationic starches than BKP since it contained more anionc functional groups on its surface. The adsorption amount of the cationic starch increased as the cationicity of the starches decreased. Surface charge density of the pulp and starch adsorption increased as the pH of the pulp slurry increased. Adsorption amount of the cationic starch onto talc was lower than that onto the pulp due to its low charge density and hydrophobic surface property.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.1
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• pp.1-8
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• 2008

It is essential to use base papers having proper surface characteristics in coating operation for improving coated paper quality and coater runnability. To fulfill these purposes, surface sizing of coating base stock with oxidized starch is commonly practiced. Use of cationic starch for surface sizing improves coated paper quality since cationic starch penetrates less into paper structure. The immediate objective of this study was to examine the influence of surface sizing with starch solutions containing cationic polymers on the rheology of coating colors and the effect on physical properties of coated papers. Changes of rheological characteristics of coating colors placed on the plastic substrate surface sized with cationic and anionic starch were determined. Results of rheological test showed that cationic polymer surface sizing agent increased electrostatic interaction with coating colors and increased storage modulus. This new technology of using cationic polymer as surface sizing additive was considered to be advantageous for base papers at low basis weights since it would improve the coverage and optical properties of coated papers.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.30-39
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• 1998

Effect of cationic starches and anionic colloidal silica on retention and drainage characteristics of Compozil system was investigated. Depending upon the degree of substitution and molecular weight of cationic starches and morphological characteristics of anionic colloidal silica, retention and drainage properties of Compozil system were significantly influenced. When cationic starch addition level increased above a certain limit retention and stock freeness were decreased. To elucidate this an electrostatic coagulation mechanism occurring between unadsorbed starch molecules and anionic colloidal silica was proposed. Unstructured colloidal silica showed greater improvement in retention than structured colloidal silica. Cationic corn starches with different degree of substitution and molecular weights were prepared and their effect as a constituent of Compozil system was also evaluated. By controlling the molecular weight and degree of substitution of cationic corn starch it was possible to achieve significant improvement in fines retention. Cationic corn starch with higher degree of substitution maintained its retention efficiency even when the stock conductivity was increased. Turbidity measurement technique was found to be a simple and useful method to measure the retention characteristics.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.4 s.117
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• pp.1-9
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• 2006

Increasing the filler content of sheet provides an opportunity for saving production cost through fiber replacement with relatively low-priced filler. But increasing the filler content tends to decrease the strength of paper and filler retention. To overcome these problems, preflocculation technology of fillers has been suggested. To evaluate the effect cationic polymers on the size and size distribution of preflocculated GCC and their shear stability, cationic PAM and cationic starch were used. Results showed that cationic PAM formed large prefloc at low dosage. It was required to add 15 times as high as cationic starch to cationic PAM to obtain the same size prefloc. But preflocs formed with cationic starch was superior in shear stability to those formed with cationic PAM. With the increase of shear rate the size of preflocs decreased. Greater amount of small preflocs or un-flocculated fillers was observed when the dosage of polymers was low and this ended up low ash retention in handsheets.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.245-250
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• 2006

This study was focused on the use of cationic PAM (Polyacrylamide) as a surface sizing additive to improve the surface sizing properties of paper. Effects of the ionic property, viscosity and charge density of PAM on bending stiffness of surface sized papers were investigated. Use of cationic PAM as a surface sizing additive improved bending stiffness while addition of anionic PAM did not show any effect. Increase of starch holdout with the addition of cationic PAM was attributed as a prime reason of stiffness increase. Viscosity of PAM was one of the most important factors affecting surface sizing due to its influence on the interaction between cationic PAM and oxidized starch solution. Greater improvement of bending stiffness of paper was obtained when high charged PAM was used as an additive. The order of addition was found to have significant influence on the effect of additives since it influences the formation of network structure among starch, cationic PAM, and SA (styrene acrylic acid copolymer). Investigation on the penetration of starch solution was carried out with CLSM (Confocal Laser Scanning Microscopy), and it was shown that the addition of cationic PAM to oxidized starch solution made starch molecules stay on the paper surface rather than penetrating into the paper structure because of the electrostatic interaction between negatively charged fibers and positively charged cationic PAM.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.625-631
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• 2015

In this study, low cost bio-flocculants, chitosan, cationic starch and Mg-sericite, were used as a flocculant to harvest freshwater microalgae, Chlorella vulgaris. Chitosan, cationic starch and Mg-sericite separated successfully >98% of C. vulgaris at following optimal parameters: 90 mg/L chitosan at pH 6-7, 70 mg/L cationic starch at pH 9-10 and 50 mg/L Mg-sericite at pH 4-5. A relatively high correlation coefficient (R²) of 0.9993 for chitosan, 0.9971 for catonic starch and 0.9924 for Mg-sericite was obtained. The investigated flocculants amount increased linearly with increasing the microalgae amount. The biopolymer, Mg-sericite, was more effective than that of other investigated flocculants. These results indicated that a bio-flocculants, chitosan, cationic starch and Mg-sericite, could prove to be an effective flocculant for economical production of microalgae biomass. In addition, Mg-sericite was more effective comparing to the other investigated flocculants.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.2
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• pp.1-12
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• 2002

Starch dissolved in paper-mill wastes, either as a result of poor retention on the paper web or recycling of surface-treated broke, was a major pollutant Laboratory tests were performed by using different kinds of starch as a surface treatment. It was concluded that the use of cationic starch can positively affect the level of starch dissolved in liquid effluents. When cationically modified starches were used for surface sizing, the starch was tightly bound to the paper fibers, it was not removed during the repulping of broke. The result of mill trial in fine paper manufacture for the application of low-viscosity cationic starches used in size press reduced COD load in the effluents and increased One Pass Retention. It had been found that when cationic starch used as a surface sizing agent, more starch was retained on or near the surface of the sheet than with conventional oxidized starches. Thus surface strengths and quality were improved. In addition it is possible to maintain the desired level of starch penetration into the fiber net and improve porosity, opacity and brightness. In contrast, in most cases, dusting problems are notably eliminated. Cationic surface sized starch improved black and color ink-jet print quality in terms of feathering and optical density of the print image. These improved properties were believed to be due to a combination of fiber bonding and surface orientation more uniform starch concentration on the paper surface was resulted. Moreover cationic charges in the paper surface lend themselves excellently to fix ink jet ink anionic in nature.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.3
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• pp.10-18
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• 1999

The influence of simple electrolyte or anionic trashes on cationic starch adsorption was examined using deinked pulp and bleached thermomechniical pulp. Adsorbed amounts of cationic starches increased slightly , then decreased abruptly as the concentration of simple electrolyte increased. This phenomenon was discussed based on the compression of electrical double layer and conformation change of starch molecules. Also, the effect of the type of simple electrolytes on starch adsorption was examined and discussed. Addition of sodium slilicate increased starch adsorption since it increased surface charge density of fibers. On the other hand, addition of kraft lignin decreased cationic demand of the pulp slurries and adsorbed amounts of cationic starches. Nonionic surfactant did not show any significant effect on the cationic demand of pulp slurries. When simple electrolytes were added to the stock , grater adsorption or cationic starches was obtained with starches of lower degree of substitution . On t도 other hand, amount of adsorbed starches decreased for lower DS starches when the concentration of anionic trashes increased.