• 펄프종이기술
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• 제35권2호
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• pp.12-17
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• 2003

The effects of wet pressing and drying conditions on the disintegration and physical properties of paper were investigated in order to get the basic information on the resistance of paper for aqueous solution during converting processes. Wet pressing of unbeaten bleached softwood kraft pulp increased WRV at the range of grammage investigated. The increase of WRV with grammage at low wet pressing pressure(50 psi) was obvious, while it was not significant at higher wet pressing pressure(110 psi). The changes of WRV by drying were affected by the grammage and wet pressing pressure. The poorer disintegration of sheet, the higher wet pressing pressure and drying temperature. Although the strength properties were increased with the grammage, wet pressing pressure and drying temperature, results showed different trend from those of beaten pulp.

• 펄프종이기술
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• 제46권4호
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• pp.21-27
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• 2014

As a part of the study on manufacture of low density paper by organic bulky agent treatment, the effects of cationic fatty acid bulky agent on physical and optical properties of handsheets were elucidated. The research on change of physical and optical properties of paper samples according to bulky agent concentration, pulp type, and pulp combination were carried out. The results demonstrated that an increase of the concentration of cationic fatty acid bulky agent was proportional to an increase of the bulky properties of paper samples while tensile strength decreased. Also, the more the treated concentration of cationic fatty acid bulky agent increased, the more the ISO brightness of paper samples decreased while the opacity increased. The effectiveness of bulky agent with softwood bleached kraft pulp (SwBKP) was higher than that with hardwood bleached kraft pulp (HwBKP). In addition, the effectiveness with mixed pulps was higher than that with single pulp.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.31-36
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• 2006

Tritium has been used to directly measure the exchangeable hydrogen in bleached softwood kraft pulp. The hydrogen atoms associated with hydroxyl groups in pulp or with water contained in the pulp can dissociate and exchange with the hydrogen atoms in bulk water. Tritium is a radioactive isotope of hydrogen and behaves almost identically to it. The distribution of tritium between pulp and water ($k_{pw}$) can be easily measured and becomes an index of the protons available fur hydrogen bonding. Bleached kraft pulp was refined in a PFI mill to a range of freenesses. Tritiated water was added and the amount exchanged measured. There was a slight steady increase in $k_{pw}$ until approximately 300 CSF; $k_{pw}$ then rose sharply between 300 CSF and 100 CSF. This rise appears to correlate with FSP. It is likely that the action of refining on the fiber reaches a threshold at about 300 CSF causing the fiber surface to break open creating exponentially more surface area. This theory is visually confirmed through light microscopy. The slow increase in fibrillation of the fibers above 300 CSF correlates with the increase in $k_{pw}$. Beyond the threshold of 300 CSF a dramatic difference in fibrillation is shown, also corresponding with the large increase in $k_{pw}$. The freeness difference around 300 CSF is small, but the change in fiber properties is extreme within this region. This change in properties could lead to sheet breaks and other disruptions when producing products around the threshold. This study leads to a better understanding of how fiber changes during refining, resulting in a practical benefit of target freeness determination. Presently, freeness is selected based on product quality and on some measure of runnability. Yet, there are other considerations, demonstrated by the extreme change in fiber properties around 300 CSF.

• 펄프종이기술
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• 제30권2호
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• pp.55-61
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• 1998

This treatment was applied to bleached softwood kraft pulp handsheets in an effort to improve physical strength of paper. Paper strength was improved by esterification of cellulose and polycarboxylic acid. Because hydrogen bond of carboxyl group is stronger than that of hydroxyl group, polycarboxylic acid forms stronger hydrogen bond than cellulose does. 1,2,3,4,-cyclopentanetetracarboxylic acid (CPTA) and sodium dihydrogen phosphate ($NaH_2O_4$) were used as polycarboxylic acid and catalyst, respectively This reaction was confirmed by the weight gain of the handsheets, by FTIR spectrum and by changes in mechanical properties of sheets. Wet tensile strength was improved when handsheets were treated with polycarboxylic acid. However, tear strength and burst strength decreased.

• 펄프종이기술
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• 제33권3호
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• pp.59-68
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• 2001

Essential oils extracted from Chamaecyparis obtusa were applied to make antibacterial corrugating liner. The quantitative analysis of the essential oils was carried out by GC-MS, which showed that the monoterpenes as a basic component of the essential oils extracted from Chamaecyparis obtusa in the domestic mountain were greater in amount than those in China. The antibacterial activity was then examined with Tyromyces palustris and gram-negative/positive bacteria. The papers treated with the essential oils desplayed great resistance against T. Palustris and gram bacteria but the best results were obtained with the handsheet formed by softwood bleached kraft pulp rather than the liner by OCC. The low antibacterial activity of the liner was considered to be due to starch components which could be readily attacked by the fungi.

• 펄프종이기술
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• 제39권1호
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• pp.1-7
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• 2007

Internal fibrillation of pulp fiber is an important factor affecting paper properties. Internal fibrillation of pulp fiber is usually introduced with several kinds of modifications of fiber by the mechanical treatment such as refining, high shear and/or high consistency mixing, etc. Unfortunately there are no standardized methods that can characterize the extent of internal fibrillation and its contribution on the paper properties. The purpose of this study is to try and find the potential methods that can characterize the internal fibrillation of pulp fiber quantitatively. Softwood bleached kraft pulp was treated with Hobart mixer to introduce the internal fibrillation without the significant fiber damage and external fibrillation. The extent of internal fibrillation was increased with the increase of mechanical treatment consistency. Several fiber properties were measured to find the potential means that could characterize and quantity the internal fibrillation. Laminated area could not be used as a means for quantifying the internal fibrillation because of the effect of swelling and the different internal fibrillation behavior at different mechanical treatment consistency. Micro and macro internal fibrillation models were proposed for describing the different behavior for the mechanical treatment at low and high consistencies of pulp. The Internal fibrillation showed good correlation with swelling of fiber wall. This trend was confirmed through the measurement of wall thickness and/or cross section area of fiber. Therefore the internal fibrillation possibly can be described as the indices indicating the change of wall thickness and/or cross section area.

• 펄프종이기술
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• 제47권4호
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• pp.38-45
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• 2015

Fold cracking is one of quality troubles of coated papers. In this study, the fold cracking of high grammage ($250g/m^2$) coated paper made with the different pulp composition and layer structure of base paper was investigated. The single layered, high grammage base paper was prepared by mixing of hardwood and softwood bleached kraft pulp fibers with the different ratios. The high grammage coated paper showed the higher fold cracking than low grammage coated paper because of the increase in thickness. The increase in the content of softwood pulp fibers reduced the fold cracking in the case of high grammage coated paper. When the creasing process was conducted before folding process, the fold cracking of coated paper decreased. By manufacturing the base paper with multiply structure, the fold cracking of coated paper could be reduced significantly, especially when the BCTMP and OCC were used as a middle layer and the creasing process was carried out. The delamination of layers in base paper affected the fold cracking positively.

• 펄프종이기술
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• 제48권3호
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• pp.37-43
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• 2016

Various mechanical and chemical pretreatment methods including alkali treatment, pre-beating, enzyme treatment and oxidation treatment have been used to reduce the production energy of the microfibrillated cellulose (MFC). Among them, alkali swelling can be helpful to reduce the energy consumption because the internal bonding between fibrils could be weakened. In this study, dimethyl sulfoxide (DMSO) was used as a cosolvent to improve alkali pretreatment efficiency and the effects of NaOH concentration during NaOH-DMSO swelling on changes in fiber characteristics of softwood bleached kraft pulp (SwBKP) were elucidated. For alkali treatment in H2O-DMSO solvents, fiber length were decreased with increasing NaOH concentration while fiber width, curl and WRV were increased. WRV began to increase at 8% NaOH solution. In addition, above 8% concentration of NaOH, crystalline structure of pulp fibers converted from cellulose II to cellulose III by DMSO cosolvent. Comparing the previous results with this study, it was shown that DMSO cosolvent could promote swelling of pulp fibers and thus reduce NaOH concentration for the maximum swelling of fibers.

• 펄프종이기술
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• 제44권5호
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• pp.1-7
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• 2012

Chemical composition, morphological properties and papermaking properties of Sasa quelpaertensis Nakai were investigated in order to use it comprehensively. The lignin contents of stalks and leaves were 18.8% and 15.3% and the holocellulose contents were 63.3% and 48.6% respectively. The contents of ash and the amount of water extract showed the higher value than those of wood or other bamboo species. The average fibers length and width of Sasa quelpaertensis Nakai were 780 ${\mu}m$ and 14.8 ${\mu}m$. The fibers of Sasa quelpaertensis Nakai stalk had thinner width and more slender structure than those of softwood. The handsheet made of Sasa quelpaertensis Nakai alkaline pulp showed higher in tensile strength and bulkier structure than those of handsheet made of soft wood unbleached kraft pulp.

• 펄프종이기술
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• 제43권5호
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• pp.60-67
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• 2011

Hemicelluloses pre-extracted from Korean mixed wood chip were investigated as a wet-end additive. Hemicelluloses dissolved in hot water and alkali solution were isolated by ethyl alcohol precipitation from pre-extractives. They showed molecular weight of 9,000 ~ 27,000 g/mol as revealed by size exclusion chromatography. The reduction of molecular weight through hot water extraction was caused by autohydrolysis. Chemical composition of the hemicelluloses were analyzed with high-performance liquid chromatography and UV-Vis spectroscopy. As the surface charge of isolated hemicelluloses were negative, the adsorption of hemicelluloses onto softwood unbleached kraft pulp fiber was promoted by poly-DADMAC. The physical properties of handsheets increased as the molecular weight of hemicellulose increased. On the other hands, the optical property decreased with hemicellulose adsorption.