• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.104-110
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• 2006

We investigated why aspen extractives are more resistant in kraft pulping than pine extractives. Residual extractives content in aspen kraft pulps were 0.5~1.1% compared with 0.1~0.2% in pine pulps. This different response arises from the different composition of extractives in wood chips. Resin acids in pine were almost completely removed in kraft pulping but those are not existence in aspen. Slower saponification of aspen steryl esters resulted from different chemical structure of aspen steryl esters. Main sterols in aspen steryl esters were 24-methyl cyclolanostenol which was highly resistant to alkaline hydrolysis with its characteristic steric hindrance. Sterols in aspen were not well removed in kraft pulping. The relative composition of sterol in aspen kraft pulps was increased with increasing pulping time. The presence of fatty acids in aspen kraft pulps is considered to unusual. Fatty acids in alkaline are supposed to be well ionized and removed well in the washing stage. Nevertheless, there were significant amount of fatty acids remaining in aspen kraft pulps.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.331-336
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• 2004

Due to the outstanding insulating characteristics, Laminated Polypropylene paper (LPP) and Kraft paper have been used as ac power insulation for conventional cable. Recently, both of LPP and Kraft has been studied as main insulation fur high temperature superconducting (HTS) cable. Ifowever, studies on the use of LPP/Kraft paper for HTS cables are thinly scattered. In this paper, the comparison among LPP, Kraft and LPP/Kraft Samples impregnated with liquid nitrogen $(LN_2)$ on dielectric insulation characteristics was investigated. It was found from the experimental data that the breakdown strength becomes lower in the order LPP, Lpp/Kraft and Kraft but the lifetime indices n becomes lower in the order Kraft, LPP/Kraft, LPP. Moreover, partial discharge inception and dielectric loss tangent become lower in the order Kraft, LPP, LPP/Kraft.

• 한국포장학회지
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• 제5권2호
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• pp.38-41
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• 1999

This study was carried out to investigate improvement of kraft paper sack mixed with recycled paper for sugars and assorted feeds. Four Plies of kraft paper mixed with recycled paper(basis weight : $80g/m^2$) were taken place of two plies of kraft paper made from all pulp(basis weight : $98g/m^2$) and one ply of kraft paper mixed with recycled paper(basis weight : $80g/m^2$) for sugar 30kg. Three Plies of kraft paper mixed with recycled paper(basis weight : $80g/m^2$) were taken place of two plies of kraft paper made from all pulp(basis weight $98g/m^2$) for sugar 15kg and assorted feed 25kg. Physical properties, tensile strength, internal tearing strength and bursting strength, were improved by exchanging kraft paper mixed with recycled paper for kraft paper from all pulp and so kraft paper sacks made from all pulp were no damage in handling. They had so high friction coefficient that there was no danger of collapse on pallet by slipperiness in transportation and handling. And they had high printability so disappearance of printing by the contact with other paper sack in transportation was not found.

• 펄프종이기술
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• 제37권3호
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• pp.74-80
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• 2005

The compositions of residual extractives in woodmeal, unbleached and oxygen-delignified aspen kraft pulps were investigated with gas chromatography(GC) and gas chromatography-mass spectrometry (GC-MS) with focus on fate of extractives in kraft pulping and oxygen delignification. Steryl esters and shorter retention time (shorter than palmitic acid) extractives were main extractives in aspen woodmeal. Shorter retention time extractives were well removed in kraft pulping. Sterol esters were hydrolyzed to sterols and fatty acids. Sterols and fatty acids were two major extractives classes in unbleached kraft pulps. Linoleic acid was main fatty acids in unbleached pulps compared with palmitic acid which is generally found in aspen woodmeal. Sterolsand fatty acids were also two major extractives classes in oxygen-delignified kraft pulps. However, linoleic acid was well removed in oxygen delignification.

• 펄프종이기술
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• 제41권5호
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• pp.20-25
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• 2009

Residual extractives had a noticeable impact on the brightness of unbleached hardwood kraft pulps (trembling aspen). The brightness-impacting extractives were effectively removed by oxygen delignification. In addition, oxygen delignification was more effective in removing chromophores in hardwood unbleached kraft pulps than in those of softwood (loblolly pine). The residual extractives in unbleached hardwood kraft pulps also affected the pulp color, primarily redness and the L value. These redness-related extractives in unbleached hardwood kraft pulps were also effectively removed by oxygen delignification. There were no significant color differences between untreated and solvent-extracted oxygen-delignified aspen kraft pulps. The residual extractives in unbleached and oxygen-delignified softwood (loblolly pine) kraft pulps did not have a significant impact on either brightness or pulp color.

• KSBB Journal
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• 제16권2호
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• pp.179-182
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• 2001

Horseradish peroxidase(HRP) 및 $H_2O_2$. 와 함께 2, $2^+$-azinobis (3-ethylbenzthiazoline-6-sulfonic acid)(ABTS)블 라디 칼 전달체로서 사용하면 kraft 펄프의 표백효율이 증가하였다. 이때 반 응에 사용할 수 있논 $H_2O_2$의 농도는 약 20 mM까지 증가시킬 수 있었다 Kraft 펄프의 표백효율은 효소의 사용량을 0 0.3 mg/90 mL 까지, ABTS의 농도를 2 mM 까지 높일수록 증가하였으나 이후에는 더 이상 증가하지 않았다. 또한 HRP 에 의한 펄프표백 효율은 효소의 활성 및 펄프에의 홉착강도 와 멸접한 관련이 있었다. HRP의 활성과 kraft 펼프의 표백 효율은 pH 7에서 가장 높았으며 산성용액과 암쌀려성 용액 에서는 강소하였다. 또한 HRP의 펄프홉착 강도는 pH 6-8에 서 가장 낮았고 산성용액(pH 5) 및 알칼리성 용액(pH 9)에서 가장 높았다 펼프의 주요구성 성분인 결정형 셀룰로즈와 려 그닌 중 려그년에 대한 효소의 흡착강도가 더욱 높았다.

• 임산에너지
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• 제17권1호
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• pp.56-70
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• 1998

This study was carried out to investigate the structural characteristics of kraft lignin and the wood degrading characteristics, the productivity of ligninolytic enzymes and the enzymatic degradation of kraft lignin by white-rot fungi. To purify kraft lignin, precipitation of kraft pulping black liquors of pitch pine meal was done by titration with lN $H_{2}SO_{4}$ reaching to pH 2, and isolation of the precipitates done by centrifugation. The isolated precipitates from pitch pine were redissloved in lN NaOH, reprecipitated by titration with lN $H_{2}SO_{4}$, washed with deionized water, and kept ofr analysis after freeze drying. Fractionation of the precipitates in solution by successive extraction with $CH_{2}Cl_{2}$ and MeOH, and the fractionates were named SwKL, SwKL I, SwKL II, and SwKL III for pitch pine kraft lignin. The more molecular weights of kraft lignin increased, the less phenolic hydroxyl groups and the more aliphatic hydroxyl groups. Because as the molecular weights increased, the ratio of etherified guaiayl/syringyl(G/S ratio) and the percentage were increased. The spectra obtained by 13C NMR and FTIR assigned by comparing the chemical shifts of various signals with shifts of signals from autherized ones reported. The optimal growth temperature and pH of white-rot fungi in medium were $28^{\circ}C$ and 4.5-5.0, respectively. Especially, in temperature and pH range, and mycelial growth, the best white-rot fungus selected was Phanerochaete chrysosporium for biodegradation. For the degradation pathways, the ligninolytic fungus jcultivated with stationary culture using medium of 1% kraft lignin as a substrate for 3 weeks at $28^{\circ}C$. The weight loss of pitch pine kraft lignin was 15.8%. The degraded products extracted successively methoanol, 90% dioxane and diethyl ether. The ether solubles were analyzed by HPLC. Kraft lignin degradation was initiated in $\beta$-O-4 bonds of lignin by the laccase from Phanerochaete chrysosporium and the degraded compounds were produced from the cleavage of $C\alpha$-$C\beta$ linkages at the side chains by oxidation process. After $C\alpha$-$C\beta$ cleavage, $C\alpha$-Carbon was oxidized and changed into aldehyde and acidic compounds such as syringic acid, syringic aldehyde and vanilline. And the other compound as quinonemethide, coumarin, was analyzed. The structural characteristics of kraft lignin were composed of guaiacyl group substituted functional OHs, methoxyl, and carbonyl at C-3, -4, and -5 and these groups were combinated with $\alpha$ aryl ether, $\beta$ aryl ether and biphenyl. Kraft lignin degradation pathways by Phanerochaete chrysosporium were initially accomplished cleavage of $C\alpha$-$C\beta$ linkages and $C\alpha$ oxidation at the propyl side chains and finally cleavage of aromatic ring and oxidation of OHs.

• 펄프종이기술
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• 제38권3호
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• pp.13-22
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• 2006

The analogs of cyclic hydroxamic acids containing N-OH group have been proposed to play effective laccase-mediators in kraft pulp bleaching with laccase/mediator system. The existing mediators (NHA, 1-HBT, VA), the best laccase-mediators reported so far, and selected several analogs of cyclic hydroxamic acids were evaluated as a laccase-mediator for kraft pulp bleaching. It was found that NHA was the most effective mediator for the Trychophyton sp. LKY-7 laccase (TrL) in kraft pulp bleaching with TrL/mediator system, increasing about 10% ISO of brightness and decreasing about 2.8 of kappa number after alkaline-peroxide bleaching. Of the cyclic hydroxamic acidstested, the NHP.1(N-hydroxypyridone analog) was shown to enable TrL to effectively degrade lignin in kraft pulp bleaching, demonstrating approximately similar effect with that of NHA. However, the effect of substituent patterns of cyclic hydroxamic acid analogs in kraft pulp bleaching was not observed. The inhibitions of NHA and NHP.1 on TrL were not exhibited in TrL/mediator system. As a new mediator for TrL, NHP.1 was considered to be able to use in kraft pulp bleaching with TrL/mediator system.

• Journal of the Korean Wood Science and Technology
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• 제29권4호
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• pp.103-110
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• 2001

목재 내 리그닌의 선택적 분해 특성을 지닌 백색부후균 중, Phanerochaete chrysosporium KCCM 34740 균주를 현사시나무 목재 칩에 전처리하여 bio-kraft pulping 적용 가능성을 실험적으로 평가하였다. 전처리 결과, 무처리 대조구에 비해 펄프의 정선수율은 전처리 10일에서 최고 약 2%의 증가를 보였으며, 전처리 기간의 증가에 따라 여수도의 감소, WRV의 증가 경향을 나타냈다. 또한 수초지의 물성 개선에도 효과가 있었으며, 주사전자현미경 관찰을 통하여 이러한 효과가 백색부후균의 생물고해 작용, 즉 펄프 섬유의 미세섬유화 및 다공질화에 기인한 것임을 확인할 수 있었다. 이러한 결과로써 향후 kraft 증해 약액 및 제지공정상의 고해 동력에너지의 소비를 절감할 수 있을 것으로 기대한다.

• 펄프종이기술
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• 제37권5호통권113호
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• pp.41-49
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• 2005

This paper deals the effect of anthraquinone (AQ) on the contribution of sulphidity in kraft pulping of sapwood. The pulping conditions namely- active alkali concentration, pulpingtime, temperature and liquor ratio were varied in low ($15\%$) and high ($30\%$) sulphidity. $0.1\%$ AQ was added in the low and high sulphidity pulping with varying active alkali concentration and cooking time. At optimum conditions, low sulphidity kraft process produced about $44\%$ pulp yield with kappa number of about 23. But in high sulphidity kraft process kappa number was reduced to about 20 at the same yield. An addition of AQ reduced alkali requirement by $2\%$ on oven dried raw material and cooking time by 1 hour to produce pulp yield of about $44\%$ at kappa number 20. AQ is more effective in low sulphidity pulping than the high sulphidity pulping. The breaking length of kraft-AQ pulp was slightly higher than that of kraft pulp.