• Title/Summary/Keyword: bleached and kraft pulp

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Effects of Kneading Concentration on Characteristics of HwBKP Fibers (니딩 처리 시 지료농도에 따른 활엽수표백크라프트펄프의 섬유특성 변화)

  • Seo, Ji-Hye;Choi, Kyoung-Hwa;Cho, Byoung-Uk
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.47 no.4
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    • pp.54-59
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    • 2015
  • In this study, effects of kneading concentration on characteristics of hardwood bleached kraft pulp (HwBKP) fibers were elucidated. A laboratory two-shaft kneader was utilized for kneading. Kneading concentration was varied in the range of 15-30% (w/w) and the number of kneading treatment was adjusted between 0 and 6 passes. It was found that kneading concentration influenced fiber characteristics. At 15% of pulp concentration, fiber length slightly increased with increasing the number of kneading passes, while other morphological properties such as fiber width and curl decreased: fiber straightening occurred. In addition, the increase in WRV and the decrease in CSF were the largest at 15% kneading concentration, meanings that fibrillation mainly occurred. In contrast, at higher kneading concentration exceeding 20%, fiber deformation like curl was mainly occurred. Also, at kneading concentration of 20% and 30%, fiber length decreased with the number of kneading passes while other morphological properties such as fiber width, and WRV increased. Severe fiber entanglement was found at 30% kneading, which shall be removed during papermaking.

Effects of Alkali Concentration on Fiber Characteristics of SwBKP during Alkali Treatment in Cosolvent System (알칼리 공용매 팽윤처리 시 알칼리 농도가 SwBKP 섬유 특성에 미치는 영향)

  • Seo, Ji-Hye;Choi, Kyoung-Hwa;Cho, Byoung-Uk
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.48 no.3
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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.

Studies on the Pulping Characteristics of Larchwood (Larix leptolepis Gordon) by Alkaline Process with Additives (첨가제(添加劑) 알칼리 법(法)에 의한 일본 잎갈 나무의 펄프화(化) 특성(特性)에 관(關)한 연구(硏究))

  • Lim, Kie-Pyo;Shin, Dong-Sho
    • Journal of the Korean Wood Science and Technology
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    • v.7 no.2
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    • pp.3-30
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    • 1979
  • Larch ($\underline{Larix}$ $\underline{leptolepis}$ GORDON), one of the major afforestation species in Korea in view of its growing stock and rate of growth, is not favored as a raw material for pulp due to its low yield of pulp and difficulties with bleaching arising from the high content of extractives in wood, and the high heartwood ratio and the active phenolics, respectively. The purpose of this study is to investigate the characteristics of firstly pulping with various additives of cellulose protector for the yield of pulp, and secondly bleaching with oxygen for chlotination-alkali extraction of five stage-sequence to reduce chlorine compounds in bleaching effluents. The kraft cooking liquor for five age groups of larchwood was 18 percent active alkali with 25 percent sulfidity and 5 : 1 liquor-to-wood ratio, and each soda liquor for sap-and heart-wood of the 15-year-old larchwood was 18 percent alkali having one of the following cellulose protectors as the additive; magnesium sulfate ($MgSO_4$, 2.5%), zinc sulfate ($ZnSO_4$, 2.5%), aluminium sulfate ($Al_2(SO_4)_3$, 2.5%), potasium iodide (KI, 2.5%), hydroquinone (HQ, 2.5%), anthraquinone (AQ, 0.1%) and ethylene diamine (EDA, 2.5%). Then each anthraquinone-soda liquor for the determination of suitable cooking condition was the active alkali level of 15, 17 and 19 percent with 1.0, 0.5 and 0.1 percent anthraquinone, respectively. The cooking procedure for the pulps was scheduled to heat to 170$^{\circ}C$ in 90 minutes and to cook 90 minutes at the maximum temperature. The anthraquinone-soda pulps from both heartwood and sapwood of 15-year-old larchwood prepared with 0.5 percent anthraquinone and 18 percent active alkali were bleached in a four-stage sequency of OCED. (O: oxygen bleaching, D: chlorine dioxide bleaching and E: alkali extraction). In the first stage oxygen in atmospheric pressure was applied to a 30 percent consistency of pulp with 0.1 percent magnesium oxide (MgO) and 3, 6, and 9 percent sodium hydroxide on oven dry base, and the bleached results were compared pulps bleached under the conventional CEDED (C: chlorination). The results in the study were summarized as follows: 1. The screened yield of larch kraft pulp did not differ from particular ages to age group, but heartwood ratio, basic density, fiber length and water-extractives contents of wood and the tear factor of the pulp increased with increasing the tree age. The total yield of the pulp decreased. 2. The yield of soda pulp with various chemicals for cellulose protection of the 15-year-old larchwood increased slightly more than that of pure soda pulp and was slightly lower than that of kraft pulp. The influence of cellulose protectors was similar to the yield of pulps from both sapwood and heartwood. The effective protectors among seven additives were KI, $MgSO_4$ and AQ, for which the yields of screened pulp was as high as that of kraft pulp. Considering the additive level of protector, the AQ was the most effective in improving the yield and the quality of pulp. 3. When the amount of AQ increased in soda cooking, the yield and the quality of the pulp increased but rejects in total yield increased with decreasing the amount of active alkali from 19 to 15 percent. The best proportion of the AQ seemed to be 0.5 percent at 17 percent active alkali in anthraquinone-soda pulping. 4. On the bleaching of the AQ-soda pulp at 30 percent consistency with oxygen of atomospheric pressure in the first stage of the ODED sequence, the more caustic soda added, the brighter bleached pulp was obtained, but more lignin-selective bleaching reagent in proportion to the oxygen was necessary to maintain the increased yield with the addition of anthraquinone. 5. In conclusion, the suitable pulping condition for larchwood to improve the yield and quality of the chemical pulp to the level for kraft pulp from conventional process seemed to be. A) the selection of young larchwood to prevent decreasing in yield and quality due to the accumulation extractives in old wood, B) the application of 0.5 percent anthraquinone to the conventional soda cooking of 18 percent active alkali, and followed, C) the bleaching of oxygen in atmospheric pressure on high consistency (30%) with 0.1 percent magnesium oxide in the first stage of the ODED sequence to reduce the content of chlorine compounds in effluent.

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Characterization of Base Paper Properties on Coating Penetration

  • Kim, Bong-Yang;Douglas W. Bousfield
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.35 no.5
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    • pp.17-25
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    • 2003
  • The influence of base paper properties and fiber type on coating penetration was studied in terms of characterization of coating holdout using two types of hand sheets as the base paper which were prepared from thermomechanical pulp (TMP) and hardwood bleached kraft pulp(KP) sized internally with alkyl ketene dimmer (AKD). Laboratory rod draw down coater was used for surface sizing and coating application. Characterization of coating penetration was done by measuring the roughness of the backside of coating layer. The backside of the coating was exposed by dissolving the fibers in a solution of cupriethylenedimine (CEO). Data show that internal sizing of base paper is effective and surface sizing is more effective to prevent coating penetration. Comparing between the two types of base papers, backside roughness of coating layer of TMP sheet is much larger and sizing is more effective to reduce coating penetration than those of KP sheet. From the result of water absorption and sizing degree after surface sizing, it seems that internal sizing slows down molecular diffusion much more than capillary penetration, but surface sizing reduces the capillary penetration. Furthermore, predominant mechanism of water into paper of TMP sheet seems to be capillary penetration, but it is molecular diffusion in the case of KP sheet.

Change of Chemical Pulp Fiber Properties with Cellulase Component($C_1$, $C_{x}$) Treatment (CelIulase 구성 요소별 처리에 의한 펄프 섬유의 특성 변화)

  • Kim, Byung-Hyon;Jeon, Yang
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.30 no.2
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    • pp.13-23
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    • 1998
  • Two major cellulase components purified with sephadex G-75 and DEAE sepharose were applied to bleached kraft pulp to inverstigate the change of fiber properties. Cellulose viscosity was very sensitive to $C_x$ component treatment (more than 15% drop was observed) while being little influenced by $C_1$, component (only 2% drop). Fiber fraction longer than 2mm was reduced by $C_x$ treatment while short fiber fraction was increased greatly by more than 15%. There was little change in fiber length distribution by combined treatment of $C_1$ 1 and $C_x$ at equal. In this case, fine contents increased by more than 2.5% at equivalent refining time. WRV and Density were increased as the amount of $C_1$ or $C_x$ treatment was increased. $C_{x}$ was main cause for increasing them. But the effect fell as enzyme dosage.

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Development of Modified Printing Hanji Using Alternative Plant Fibers (II) - Printability of Printing Hanji Made of Alternative Plant Fibers - (대체 식물 자원을 이용한 인쇄용 개량한지의 개발 연구(제 2보) - 대체 식물 자원 섬유를 이용한 개량 한지의 인쇄 특성 연구 -)

  • Lee, Ji-Young;Seo, Jeong-Min;Kim, Chul-Hwan;Eom, Tae-Jin;Park, Hyun-Jin;Kim, Sung-Ho;Kim, Gyeong-Chul
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.43 no.2
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    • pp.16-23
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    • 2011
  • This study was carried out to develop the printing Hanji made of mixed raw materials with mulberry bast fibers and alternative plant fibers such as bamboo, soybean stalks, pepper stalk and sea tangle. All alternative plant fibers were produced by the kraft pulping method with 2 stages of bleaching, and used to prepare the modified traditional paper, Hanji for printing purpose. Printing quality of modified Hanji was analyzed by measuring area and Formcircle of halftones and comparing a letter shape printed on paper. The Hanji made of 60% of mulberry bast fibers and 40% of bamboo bleached kraft pulp showed the best printing quality with the smallest area and the largest Formcircle in all modified Hanji. Through the image analysis of form circles of the letters printed on the Hanji, it could also be confirmed that the best printability of the modified Hanji was made using bamboo fibers.

Effect of Beating and Pressing on Fracture Toughness of Paper (고해와 압착처리가 종이의 파괴인성에 미치는 영향)

  • 윤혜정;신동소
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.32 no.4
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    • pp.1-9
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    • 2000
  • As the speed of the paper machine and printing press increases, the dependency of the production efficiency upon the frequency of web break increases. It is believed that flaw or crack that presents in paper is one of the most important for web break. Runnability of papers on the paper machine could be evaluated by measuring fracture toughness. In this paper the effect kof beating and pressing on the runnability was investigated using handsheets made from softwood bleached kraft pulp beaten to different freeness. Pressing pressure was also varied to obtain different levels of sheet consolidation. Density, tensile strength, and J-integral of the handsheets were evaluated. For measuring J-integral either a single specimen method or RPM method was employed. Results showed that the density and tensile strength were improved as beating and pressing increased because of increased interfiber bonding. J-integral increased with beating until the CSF reached 400mL. No significant difference in J-integral, however, was observed afterward with the increase of beating. And it appeared to be due to acceleration of the stress concentration around the crack that exists on the fiber wall of the sheet when cracks exists.

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Change of Dimensional Stability and Dip Elongation of Handsheets Depending on Wet Pressing (습부압착에 따른 수초지의 치수안정성과 침지신장성의 변화)

  • Park, Chang-Soon;Lee, Jin-Ho;Kil, Jung-Ha;Park, Jong-Moon
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.43 no.4
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    • pp.31-39
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    • 2011
  • One of the main drawbacks of wood fibers based composite materials are their tendency to swell due to moisture uptake in wet and moist environments. The main contribution to the hygroexpansion usually comes from the hydrophilic wood fibers. Recent trend toward the high speed printing, copying, and precision converting precesses demands a high level of dimensional stability under various environmental conditions. The purpose of this study was to investigate the dimensional stability of softwood bleached kraft pulp handsheets depending on wet pressing conditions. By increasing the number of wet pressing, dimensional stability was decreased because of increased fiber-to-fiber bonding. Hygroexpansion of handsheets had a linear relationship with the relative bonded area and equilibrium moisture contents. Dip elongation was decreased when the number of wet pressing was increased because of increased fiber-to-fiber bonding to resist low load in water.

Studies on the Quality Improvement of Printing Paper by Process Controlling of DIP and TMP (탈묵펄프 및 열기계펄프의 공정 조절을 통한 인쇄용지의 품질향상 연구)

  • Hwang, Sung-Jun;Lim, Jong-Keun;Kim, Hyoung-Jin;Chung, Sung-Hyun
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.47 no.5
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    • pp.5-14
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    • 2015
  • Recently, the use of wood resources has been limited due to global environmental change, like global warming and desertification. It is very critical in Korea's paper industries because lots of virgin pulp are dependant on direct import from abroad for printing grade of paper. In this work, the alternatively best available technique for reducing the import amounts of BKP (bleached Kraft pulp) was considered by mixing DIP (deinked pulp) and TMP (thermomechanical pulp) for the manufacture of high quality paper. Generally known, the sheet prepared from fibrous raw materials of DIP and TMP has lower strength and optical properties than that prepared from BKP. This study was aimed to improve the sheet quality by using DIP and TMP. 4 kinds of polyelectrolytes were approached to find out the best effects on physical strength and optical brightness improvements, and high retention behaviors with GCC (ground calcium carbonate). In conclusion, amphoteric PAM with 1,000,000 molecular weight (g/mol) and 0.5 charge density (meq/g) was best for the improvement of strength properties with the mixture of DIP and TMP. GCC retention rate was also the highest with cationic-PAM of above 2,000,000 molecular weight (g/mol) and about 2.0-3.0 charge density (meq/g) of strengthening agent.

Characteristics of Paper making fiber with Synergism and Combined effect of Purified two major Cellulase Components Treatment (I. The effects of Cx components contents) (정제된 Cellulase 구성요소간 상승작용이 펄프섬유의 특성에 미치는 영향 (제1부 Cx 구성요소비에 의한 변화))

  • 김병현;신종순
    • Journal of the Korean Graphic Arts Communication Society
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    • v.16 no.3
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    • pp.157-170
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    • 1998
  • To investigate the most effective way of cellulase utilization on paper making process and the systematic way of how to combine its components for better use, purified two major cellulase were applied to bleached kraft pulp at various dosage in the refining process and estimated the synergism effect of each components in the characteristics of papermaking fiber. freeness was not changed by $C_1$ Component dosage but strongly increased by Cx Component dosage. Drop in fiber viscosity, increase in WQV, fiber shortening and fine generation was strongly influenced by Cx Component, it seems to be that Cx Component works a hydrogenate that breaks hydrogen bonding in fiber and enhances pooling effect of fiber. $C_1$ Component was little influenced these characteristics of fiber but considered to help to make fiber surface smooth.

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