化学还原处理改善杨木过氧化氢机械浆白度稳定性研究

分别采用硼氢化钠、亚硫酸氢钠及其混合物处理杨木APMP漂白机械浆，优化了处理条件，研究了不同化学药品对纸浆还原处理后改善白度稳定性效果。结果表明硼氢化钠处理杨木漂白化机浆不但能够显著改善其白度稳定性而且对纸浆具有漂白作用。加入亚硫酸氢钠混合处理纸浆可大幅度减少硼氢化钠用量，并能取得类似的改善纸浆白度稳定性效果。杨木碱性氧化氢漂白机械浆光诱导返色有其固有特点，傅立叶红外光谱显示，纸浆木质素中的羰基和酚羟基结构基团是引起纸浆光诱导返色的主要原因。     

学原处理改善杨木过氧化氢机械浆白度稳定性研究

分别采用硼氢化钠、亚硫酸氢钠及其混合物处理杨木APMP漂白机械浆，优化了处理条件，研究了不同化学药品对纸浆不处理后改善白度稳定性效果。结果表明：硼氢化钠处理杨木漂白化机浆不但能够显著改善其白度的稳定性而且对纸浆具有漂白作用。加入亚硫酸钠混合处理纸浆可大幅度减少 氢化钠用量，并能取得类似的改善纸浆白度稳定性效果。杨木碱性过氧化氢机械浆光诱导返色有其固有特点，傅立叶红外光谱显示，纸浆木质素中的羰基和酚羟基结构基团是引起纸浆光诱导返色的主要原因。     

BRIGHTNESS STABILIZING EFFECT OF UV-ABSORBERS AND RADICAL TRAPPER ON POPLAR APMP PULPS

高得率纸浆残余木质素中对紫外光和近紫外光高度敏感的特定化学结构,结合大气中的氧分子,通过形成游离基中间体而产生发色物质,导致高得率纸浆的光返色(返黄)。紫外吸收类化合物、游离基捕获剂或抗氧剂等处理纸张制止纸张返色的研究已有报道。本文研究了杨木APMP纸浆手抄片添加紫外吸收类化合物(Tinuvin 1130及其前驱物)、游离基捕获剂(氮氧游离基化合物)和抗氧剂(PEG 300)等的工艺条件和方法,对比研究了不同溶剂介质下(有机型和水溶液),添加剂对杨木APMP原浆和还原处理白度稳定性效果。结果表明,Tinuvin 1130与脂肪醇混合物处理还原后,纸浆抗光诱导返色效果尤为显著,该技术方法十分接近工业应用条件,具有潜在的工业应用价值。     

离子液体预处理对纸浆酶漂效果的研究

以杨木碱性过氧化氢机械浆(APMP)、化学热磨机械浆(CTMP)、硫酸盐浆(KP)和麦草CTMP 4种浆为原料,对纸浆在应用生物酶漂白前利用离子液体进行温和预处理,控制离子液体BmimC l用量为1.0%(以绝干纸浆质量计,下同)、EmimD MP用量为1.2%,研究发现离子液体预处理可明显改善纸浆的酶漂效果,且EmimD MP的效果更优。表现为应用离子液体预处理后成纸的光学性能及物理强度明显改善,EmimD MP预处理后杨木KP浆白度可提高4.27%(ISO),不透明度增加了2.46%,麦草CTMP成纸的抗张指数、耐破指数、环压指数、撕裂指数及耐折度分别增加12.21%、29.80%、22.45%、44.82%和52.50%。纤维质量分析仪(FQA)、X射线衍射(XRD)和扫描电镜(SEM)分析结果显示,离子液体处理后4种纸浆纤维质量提高,平均长度增加,细小纤维含量降低,纤维结晶度提高,其中EmimD MP处理后杨木KP浆结晶度提高了11.21%,纸浆表面发生明显分丝帚化,增加了药液的渗透能力。     

酶处理对混合杨木P-RC APMP浆打浆性能的影响

探讨了纤维素酶、木聚糖酶处理对混合杨木温和预处理和盘磨化学处理的碱性过氧化氢机械浆(P-RC APMP)的打浆性能和打浆能耗的影响。结果表明:与未经过酶处理浆相比,纤维素酶和木聚糖酶处理可明显改善纸浆的打浆性能和降低打浆能耗,纸浆打浆度提高1.0～6.5°SR,或在相同打浆度下打浆能耗降低10%～25%。纤维素酶处理浆裂断长提高18%,撕裂指数提高14%,耐破指数提高16%,耐折度提高100%。木聚糖酶处理纸浆白度提高1.7度(ISO),纸浆物理强度略有上升。纤维素酶在改善纸浆打浆性能、降低打浆能耗和提高物理强度方面好于木聚糖酶,木聚糖酶在改善纸浆光学性能方面优于纤维素酶。酶处理可以使纸浆纤维结构变得疏松柔软,从而增强纤维间的交织能力。     

纤维素酶预处理对杨木APMP浆配抄性能的影响

为了改善杨木高得率浆的配抄性能,扩大其应用范围,研究探讨了纤维素酶预处理对杨木碱性过氧化氢机械浆(APMP浆)配抄性能的影响。结果表明,与未经过酶预处理的杨木APMP浆相比,酶处理后APMP浆打浆能耗最大可降低19%,纤维吸水润胀程度增加,保水值增加12.6%;与不同比例针叶木漂白硫酸盐浆(BKP浆)配抄后,纸张的裂断长、耐破指数和撕裂指数均有所提高,最大可分别提高6.1%,44.6%和30.3%,纸张的松厚度、白度和不透明度稍有降低。纤维质量分析仪(FQA)、扫描电镜(SEM)和X射线衍射(XRD)分析结果显示,酶处理后纤维平均长度增加7.0个百分点,细小纤维组分减少10.0%,纤维卷曲指数降低22.4%,结晶度提高0.7%。可见,纤维素酶预处理可以改善杨木APMP浆的配抄性能,提高纸浆纤维质量,所配抄的纸张的物理强度性能指标有显著提高。     

杨木高得率制浆技术的最新进展

本文介绍了杨木的纤维特性、化学成份和利用杨木生产高得率纸浆的适应性,以及杨木为原料的漂白化学热磨机械浆（ＢＣＴＭＰ）和碱性过氧化氢化学机械浆（ＡＰＭＰ）。ＡＰＭＰ是９０年代研制成功的高得率制浆新方法,其特点是纸浆得率高、白度高和强度好。该法适用于针阔叶木,特别是杨木。杨木ＡＰＭＰ可代替部分长纤维针叶木浆,配抄低定量胶印新闻纸和涂布纸等。     

栎木乙酰化的研究

本试验不用催化剂和有机溶剂,而仅用乙酐对三种栎木(栓皮栎、麻栎和白栎)进行了乙酰化的研究,结果表明:这种简化的乙酸化处理可使栎木的干缩系数和平衡含水率显著降低,白栎木材的体积干缩系数由原来的很大级降为大级,而栓皮栎和麻栎木材的则由很大级(心材)或大级(边材)均降为中级。经处理后栎木的尺寸稳定性得到了改善。     

木聚糖酶处理改善速生杨化学机械浆性能的研究

用木聚糖酶处理速生杨化学机械浆(APMP),通过分析检测处理后纸浆的打浆度和成纸物理性能,探讨了木聚糖酶处理对速生杨高得率浆抄造性能的影响.实验结果表明,与未经过木聚糖酶处理APMP浆相比,酶处理后纸浆的打浆度降低10°SR以上,返黄(PC)值下降0.28,抗张指数和耐破指数稍有降低,而撕裂指数提高0.34mN*m2/g,不透明度提高1.1%,松厚度提高0.08cm3/g,戊聚糖含量降低1.64%,酸溶木质素含量稍有降低,纤维素含量和Klason木质素含量相对提高.木聚糖酶处理速生杨高得率纸浆,主要降解纸浆中的木聚糖,对纤维素大分子影响较小.     

麦草化学机械制浆预处理方法研究

使用麦草原料制取漂白化学机械浆,为了后续多段漂白能够获得高白度的纸浆,研究了3种不同的化学药品用于预浸渍阶段对未漂白浆的光学和物理性能的影响,包括成浆白度、成浆强度指标、纤维筛分级分,并比较了磨浆的比能耗和废水污染负荷.研究结果表明,与碱性过氧化氢(2.0%NaOH、1.5%H2O2、0.4%DTPA)处理(P工艺)磨浆相比亚硫酸钠(2.0%Na2SO3、2.0%Na2CO3、0.4%DTPA)预处理(S工艺)磨浆比能耗降低了33%,果胶酶(10IU/g以绝干浆计)/碱性过氧化氢(2.0%NaOH、1.5%H2O2、0.4%DTPA)预处理(Pe/P工艺)也可以降低磨浆比能耗10%,P工艺预处理与S工艺预处理均能提高成浆白度,Pe/P工艺预处理成浆呈现暗红色;P工艺预处理成浆物理强度高于其他两种浆;S工艺预处理磨浆段废水化学耗氧量(COD)发生量较高,达到84.09kg/t(以绝干浆计).     

紫外吸收剂和游离基捕获剂对杨木APMP纸浆白度稳定效果的研究

高得率纸浆残余木质素中对紫外光和近紫外光高度敏感的特定化学的。结合大气中的氧分子,通过形成游离基中间体而产生发色物质,导致高得率纸浆的光返色（返黄）。紫外吸收类化合物、离基捕获呈抗氧剂等处理纸浆罅纸张返色的研究已有报道。本文研究了杨森ＡＰＭＰ纸浆手抄片添加紫外吸收类化合物、游离基捕获剂和抗氧剂等的工艺条件效果。结果Ｔｉｎｕｖｉｎ１１３０与脂肪醇混合物处理还原,纸浆抗光诱导返色效果尤为显著,该技术方     

A novel method of acetylation of wood using supercritical carbon dioxide

Sugi heartwood was acetylated with acetic anhydride in supercritical carbon dioxide (CO₂) (120°C or 130°C, 10–12 MPa). As a result, the weight percent gain increased with increasing acetylation time up to 16%–20% at 1 h and 24%–28% at 24 h. The antiswelling efficiency of the acetylated specimens reached 75%–80% at 3–4 h of acetylation. It is supposed that the acetylation in supercritical CO₂ has a high bulking effect compared with liquid-phase and vapor-phase acetylation with uncatalyzed acetic anhydride. The results showed that the acetylation progressed rapidly because supercritical CO₂ and acetic anhydride formed a single phase at more than 90°C, and the acetic anhydride reached the reaction sites in the wood quickly.     

Industrial utilization of tobacco stalks II: preparation and characterization of tobacco pulp by steam explosion pulping

Our previous paper showed tobacco stalks to posses the characteristics of a raw material for pulp and paper application. It contains the major biomass constituents and cell components common to wood species. In this study, preparation and characterization of tobacco stalk pulp by steam explosion (SE) pulping at two chemical pretreatments were attempted. Chemical pretreatment prior to SE pulping improved the brightness, yield, and strength properties of the resulting tobacco SE pulps in the order: 6% Na₂SO₃ + 1% NaOH > 6% Na₂SO₃ > control (untreated). The 6% Na₂SO₃ + 1% NaOH-impregnated tobacco stalks produced SE pulps of good fiber length distribution and considerable properties that compare well with pulps from other raw materials obtained from previous studies, and the nonimpregnated ones showed strength properties superior to those of their poplar counterpart. Prior to bleaching, pretreating the tobacco stalk SE pulps with two stages, 2% NaOH at 90°C, improved the initial pulp brightness by about 5 points. Two-stage 6% H₂O₂ bleaching gave a comparable effect with hypochlorite bleaching for both tobacco and poplar, giving a 29–34 brightness point increase for tobacco SE pulp and 61 for the poplar samples. The differences in the bleaching responses for untreated tobacco and poplar SE pulps were attributed to the differences in their lignin structure, as shown in the total yield of their respective nitrobenzene oxidation products and FT-IR spectra. Tobacco SE pulps contain more of the guaiacyl-type lignin and poplar the syringyl-type lignin.This paper was presented in part during the 1998 CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) Congress, Brighton, UK, October 1998     

Dyeability of Chemically Treated Wood and its Discoloration by UV-ray Irradiation

INTRODUCTION Wood is far from a stable material. One of the biggest challenges for woodworking is learning to work within the constraints of wood properties. Discoloration of wood directly influences the decorative performance of wood products. Therefore, the degree of color change is a critical factor that determines the utilization area of dyed wood (Sakuragawa Satoshi, 1996). Discoloration has occurred because the wood components and dye molecules are degraded by UV-ray (Kaneko Shin…     

Potassium acetate-catalyzed acetylation of wood at low temperatures II: vapor phase acetylation at room temperature

Ezomatsu wood blocks were impregnated with potassium acetate (KAc) and then exposed to acetic anhydride vapor at 25°C and 120°C. The KAc-impregnated wood was rapidly acetylated at 120°C, and only 6 min was needed to achieve 20% weight percent gain (WPG). The WPG increased with increasing catalyst loading (CL), but it turned to decrease above 20% CL probably because the diffusion of acetic anhydride vapor was hindered by excess KAc depositing in the cell lumina. Thus, careful control of CL is necessary in the vapor-phase acetylation. KAc was also effective in catalyzing the vapor-phase acetylation at 25°C: the KAc-impregnated wood attained 20% WPG within 7 days, whereas the WPG did not exceed 10% even after 1 month in the uncatalyzed system. Irrespective of treatment methods, the hygroscopicity of wood was reduced and its dimensional stability was improved with an increase of WPG. These results confirm that the use of KAc simplifies the acetylation process at room temperature with minimal loss of acetic anhydride.     

European hardwoods versus Eucalyptus globulus as a raw material for pulping

The importance of eucalypt as a raw material for pulping is steadily growing. Eucalyptus globulus was compared with European hardwood species using two alkaline pulping processes, kraft and alkaline sulfite, anthraquinone pulping (ASA), which is a recently developed modified alkaline sulfite process. All cooks were performed to similar kappa numbers. Poplar cooks resulted in the highest yields followed by eucalypt and birch which were on the same level. Yield of beech pulps was definitely lower. ASA pulps show a moderate higher yield due to the less alkaline pH-profile of the cooking liquor. This yield advantage was maintained and even enhanced after TCF-bleaching. The bleaching response of all pulps was excellent. The birch pulps had the highest tensile strength followed by the poplar and beech pulps. Surprisingly eucalypt pulps had the lowest tensile strength. But this was compensated by the very good tear index of eucalypt pulps. The runnability factor, as an index for the overall strength potential, was on the same level for all pulps. Due to the higher hemicellulose content of the ASA pulps their tensile strengths were higher, but tear strengths lower compared to the kraft pulps. The different morphology of the hardwoods investigated resulted in different volumes and light scattering coefficients of the corresponding pulps. Dedicated to Prof. Dr. Dr. h. c. mult.Walter Liese on the occasion of his 80th birthday.     

On the selectivity of ozone delignification of softwood kraft pulps

Summary Ozonation of kraft pulp and oxygen-delignified kraft pulp in acetic acid/water mixtures has been studied at different pulp consistencies with and without an inhibitor to obtain information about the limitations of the selectivity of the ozone treatment. The experiments have been performed according to a full factorial design and data have been analysed by stepwise regression analysis. The results show that a better delignification selectivity can be achieved when ozone is applied in acetic acid media instead of conventional aqueous media. By combining conventional oxygen delignification and ozonation in acetic acid, pulps with equal strength properties and better optical properties compared to those of conventional O(DC)E prebleached pulps can be obtained. This study has also revealed that the reagent is utilized far more efficiently in ozonation at high pulp consistency (35%) than in ozonation at low consistency (1%), and that a similar selectivity can be achieved in both types of ozonation by choosing appropriate conditions. The greater selectivity of ozonation in acetic acid than in water is interpreted in terms of different stabilities of the oxidant in these reaction media. The relation between the formation of hydroxyl radicals and the extent and selectivity of delignification during ozonation has been investigated. The final bleaching of pulps prebleached with ozone in acetic acid medium has been studied. Two final bleaching sequences are presented, by which pulps with ISO brightness levels of 79% and 90% can be produced.The authors are indebted to the Swedish National Board for Technical Development (Styrelsen för Teknisk Utveckling) for financial support for this work and to STORA Technology for pulp tests and analyses     

Postia placenta decay of acetic anhydride modified wood – Effect of leaching

Abstract

It is well established that acetylation of wood by the use of acetic anhydride is able to impart a significant degree of decay resistance. The aim of this work was to study how a standardized leaching procedure with water (EN 84) affected the degradation of acetic anhydride modified samples by the brown rot fungi Postia placenta compared to no leaching prior to incubation. Three different levels (low, medium, and high) of acetic anhydride modified Southern yellow pine (SYP; Pinus spp.) were tested. The samples were harvested after 4 and 28 weeks. We compared changes in mass loss, wood moisture content, fungal DNA, and gene expression from five genes. If leaching changes the acetylated samples and makes them more susceptible for fungal deterioration, the expected effect would be higher levels of these parameters. Generally, leaching resulted in few differences between leached and nonleached samples at low levels of acetylation, while no changes were found for the highest acetylation level. No differences were found in gene expressions after 28 weeks. The possible protection of acetylated wood against oxidative fungal degradation is suggested to be interpreted in combination with the lowered wood moisture content.