漂白胶贮存性质的研究(二报)——紫胶树脂在漂白过程中性质变化的研究

本文研究了紫胶树脂在漂白和脱氯过程中分子量、热寿命、酸价、碘价、羟基值和氯含量的变化情况。结果证明:漂白过程中,氯主要以自由基加成的方式进入紫胶树脂,同时还有氯的自由基取代和树脂上醛基、伯羟基的氧化反应。在脱氯过程中,漂白胶树脂上大部分危害其贮存性的结合氯被除去,这些氯通过消去和取代反应脱离树脂,同时产生双键和羟基。脱氯后仍残留在紫胶树脂上的氯相当稳定,难以自行脱落,经过脱氯处理,漂白胶具备了片胶所具备的优良性质。     

紫胶漂白胶的稳性试验

紫胶经漂白之后,热寿命显著下降。由于漂白胶寿命短促,因此易于老化变性,不溶于酒精。为了解决漂白胶的老化变性问题,我们自1973年下半年以来,对漂白胶的稳性进行了一些研究。紫胶在漂白过程中,由于氧和氯的作用,加速虫胶分子的缩聚,使活性基团大大减少,寿命大大降低。如漂白液浓度过大,用量过多,反应进行猛烈,结果就会完全聚合而不能用了。另一方面,漂白胶的寿命是短促的,当将其脱水干燥之后,在空气中,由于受     

紫胶树脂链状组分紫胶桐酸漂白机理的研究

根据漂白紫胶脱氯反应过程中工艺参数改变时脱氯速度曲线形状呈明显规律性变化，以及氯含量常规测定方法无法测出紫胶树脂环状组分上稳定态结合氯的事实，证实紫胶树脂链状组分上的结合氯含量比原先估计的要高，且该部分结合氯较易脱落，从而为寻找最佳脱氯工艺条件提供了进一步的理论依据。     

将浮渣胶(molamma)制成漂白胶——虫膠工业副产品利用之一

将通常用于粒胶制造漂白胶的方法稍加改变即可适用于浮渣胶的精制。开始时,在较低温度(50℃)用碱液进行较长时间(4小时)的抽提。这样获得的漂白胶的各方面性能均与用粒胶制成的漂白胶相当,甚至贮存稳定性还更好一些。制作方法:浮渣胶经30目筛子筛分,筛下部分即作为制造漂白胶的原料,筛上部分主要是木质物质和另外一些无用物质,弃去不用。首先测定原料中的虫胶含量(热乙醇可溶物)。碳酸钠的用量相当于浮渣胶中虫胶含量的10%,溶于漂白时所需量的水中。碱液加热至55℃,在不停搅动的条件下,逐步加入浮渣胶。并经常加入少量热水,使溶液维持在50℃,     

漂白紫胶贮存性质的研究(第四报)——紫胶树脂环状组分卤化反应动力学的研究

为了解NaClO与紫胶树脂反应的规律,用壳脑酸与NaClO及壳脑酸二甲酯与溴反应,模拟了紫胶树脂与游离氯间的反应。结果表明NaClO与壳脑酸的反应为一表观复杂反应,反应前15min进行得很快,降低pH和提高温度均可加速反应。溴与壳脑酸二甲酯反应的活化能为66.2kJ/mol。由此可知,用NaClO漂白紫胶时,游离氯必然会进入树脂,成为树脂的结合氯,从而危害漂白紫胶产品的贮存性。     

催化加氢制备低氯漂白紫胶及其表征

制备和表征了在食品及制药业中广泛使用的天然低氯漂白紫胶.通过在次氯酸钠漂白改性后的紫胶碱性溶液中加入Ni-Fe二元金属催化剂,升温至90℃后,通入氢气,氢气流速为50mL/min,进行加氢离解反应240min,脱除漂白过程中加成到紫胶分子环状萜烯酸双键上的结合氯,从而获得低氯天然漂白紫胶.借助有机元素分析仪、红外光谱及紫外光谱表征了制备的产物结构,探索了催化加氢制备低氯漂白紫胶的反应机理.结果表明:制备的产物氯质量分数为0.44%,同催化加氢脱氯前的2.54%相比不到1/5;在催化加氢过程中主要发生取代反应,漂白过程中结合到紫胶分子上的氯被氢依次取代.     

漂白紫胶贮存性质的研究(第三报)——紫胶树脂卤化及脱卤反应产物结构的研究

为了证实紫胶漂白过程中生成的不稳定结合氯和稳定结合氯在树脂分子上的位置,用壳脑酸和壳脑酸二甲酯与溴反应模拟了紫胶树脂与游离氯之间的反应。两者的溴加成产物分别为α,β-二溴壳脑酸和α,β-二溴壳脑酸二甲酯,后者的脱溴产物为β-溴壳脑酸二甲酯.用各种波谱确定了上述3个化合物的结构.实验展示了在漂白过程中游离氯加成在紫胶树脂的萜烯酸双键上生成α,β二氯衍生物,脱氯时α位结合氯和β碳原子上的一个氢原子作为氯化氢脱落而恢复双键,留下β位上稳定的结合氯.     

漂白紫胶加工新技术的研究通过鉴定

由中国林科院林产化学工业研究所承担的“漂白紫胶加工新技术的研究”于1993年4月17日在南京通过技术鉴定。鉴定会在江苏省科委主持下进行的。由高等院校、科研单位、生产厂家的教授、专家、工程技术人员组成的鉴定委员会,认真听取了课题负责人所做的技术报告,并进行了充分的讨论,专家们认为:该项新技术从基础理论着手,通过对漂白紫胶脱氯的化学反应、产物理化性     

漆酶-介体系统处理麦草化学浆全无氯漂白性能的研究

采用漆酶－介体系统对麦草化学浆进行预处理，研究了几种全无氯漂白（TCF漂白）[氧碱脱木质素配合两段过氧化氢漂白（OEPP），两段过氧化氢漂白（QPP）和过乙酸配合一段过氧化氢漂白(PaP)]对漆酶处理后纸浆漂白性能的作用，结果表明，麦草浆经过漆酶预处理后，白度上升了12．9个白度单位（%,ISO)，漆酶处理浆氧碱脱木质素配合过氧化氢漂白后比原浆在相同条件下漂白后白度高14个白度单位以上，经两段过氧化氢漂白后白度比原浆在相同条件下（过氧化氢用量4％）漂白后白度高18．3个白度单位，经过乙酸过氧化氢漂白后比原浆在相同条件下漂白后白度高8．1个白度单位。漆酶处理浆漂白后强度比原浆漂白后的低，但是其白度高，如漂至相同的白度可以节约大量漂剂，有利于改善浆的质量，降低漂白废水的污染负荷。     

浸胶竹束贮存时间对酚醛树脂胶合性能的影响

将竹材制成浸胶竹束进行运输和贮存,是解决竹材原料供应范围小,运输贮存成本高的问题。但需要考虑原料贮存时间是否会影响胶粘剂反应活性,为此,研究将浸胶竹束分别贮存1.5 个月、4.5 个月和6.5 个月与未贮存的浸胶竹束进行对比,采用差式扫描量热法分析竹束中胶黏剂反应活性;并将不同贮存时间的浸胶试验进行压板,测试板材性能变化。研究结果表明：经1.5 个月和4.5 个月贮存后的竹束热焓与刚浸胶干燥后竹束热焓差别不大;不同贮存期浸胶竹束压制的板材各项性能虽有小幅度的波动,但差异不显著。因此浸胶竹束在放置6 个月内再进行压板,对板材性能和使用无影响,竹材就地加工浸胶是可行的技术方案。     

信德紫胶虫胶质特性研究

我国紫胶生产虽有几百年的历史,但由于虫种单一,胶质较差,不能满足一些特殊部门的需要。据国内用户反应,国产虫胶存在颜色深、变色快、稠度大、粘着力差、抗腐蚀性弱、漆膜透明度差等缺点。为改善我国虫种单一、胶质差的状况,1980年以来,由国家科委和林业部派出紫胶考察组,先后对南亚四个生产国进行考察,引进四个虫种,经培育筛选出两个优良虫种,信德紫胶虫是其中之一。确认优良虫种除了生物学指标外,还要看它分泌的胶是否优质。本研究着重从原胶树脂含量、颜色指数及稳定性能等方面来探讨信德虫胶质特性。     

Oxidative cleavage of lignin aromatics during chlorine bleaching of kraft pulp

Methanol liberation and methoxyl loss during chlorine bleaching of softwood kraft pulp were quantitatively investigated to estimate the degree of structural modification of lignin aromatics. An increase in the chlorine multiple led to enhanced methoxyl loss from lignin. Our result, using pH-adjusted chlorine water (pH 5.7), by which chlorination under oxidation-favorable conditions was achieved, strongly supported the importance of the oxidation reaction by chlorine during delignification and lignin degradation. It was also suggested that methanol can be produced not only via catalytic hydrolysis by chlorine but via oxidative cleavage of the ether bond as well. The infrared spectrum of chlorolignins suggested that chlorine oxidation can open aromatic rings to muconic acid derivatives without cleaving ether bonding of the methoxyl group. No straight relation between the methoxyl content and the kappa number of chlorinated pulps was shown. The methoxyl content of bleached kraft pulps subjected to successive chlorination and alkali extraction showed a good relation with the kappa number. This means that almost all the portions of the oxidatively modified lignin structure were successfully removed during these treatments, and the aromatic structures of residual lignin in chlorinated and alkali-extracted pulps were thought to remain intact.Part of this paper was presented at the 46th Annual Meeting of the Japan Wood Research Society, Kumamoto, April 1996; the 10th International Symposium on Wood and Pulping Chemistry, Yokohama, June 1999; and the 67th Pulp and Paper Research Conference, Tokyo, June 2000     

油墨专用紫胶树脂的研制和应用

研究漂白紫胶加工改性为油墨专用树脂的工艺，使其既保持天然紫胶树脂的一系列优良特性，又适应其在油墨加工中的应用。文章阐述了专用树脂在各类油墨中的使用及特性，既扩大了紫胶树脂的用途又开发了油墨新产品，该树脂有良好的应用前景。     

国内外紫胶深加工技术现状及趋势

综述国内外紫胶结构的差异,紫胶深加工产品紫胶蜡、紫胶色素、紫胶桐酸、漂白胶的国内外生产技术及工艺;阐述紫胶改性、漂白机理、漂白紫胶脱氯技术及紫胶新应用领域等国内外紫胶深加工技术研究及发展趋势;最后,提出紫胶深加工技术研究的方向和建议.     

CIEL*a*b* Measurements to Determine the Role of Felling Season,Log Storage and Kiln Drying on Coloration of Silver Birch Wood

The effects of felling season, log storage and kiln drying on stemwood discoloration of sixty mature silver birches ( Betula pendula ) were studied and provided with CIEL*a*b* colour coordinates. The colour differences were expressed as j E* including split up of j L*, j a* and j b*. The results showed that fresh wood colour depends on the felling season: light and pale colours were recorded for samples taken from autumn- and winter-felled trees, whereas the colour of fresh wood was considerably darker if the felling took place in the spring or summer. After storage, notable changes in colour were observed. After drying, all samples showed low lightness, moderate redness and relatively high yellowness under the drying conditions used in the study regardless of the felling season or duration of storage. The main colour component responsible for the discoloration was lightness, while chroma values redness and yellowness played a minor role.     

The influences of log storage and kiln drying climate on the colour of non-steamed beech (Fagus sylvatica L.) wood

Abstract

Discolouration during the drying of non-steamed beech is a major industrial concern. The generally preferred yellow-white colour can easily develop a reddish or dull grey appearance during drying. In this study, the influences of log storage time and kiln drying climate on the colour of non-steamed sawn beech have been investigated and quantified. Samples 27×87 mm in cross section were dried in laboratory kilns and the average colour, in CIELAB colour space was measured on dry planed surfaces using a photoelectric colorimeter. Log storage for 13 weeks under low-temperature conditions had no visible effect. The reddish discolouration is mainly temperature related while the greyish discolouration is mainly controlled by the equilibrium moisture content (EMC) during the initial drying. Within the investigated climate interval, the EMC was twice as important as temperature for the final colour. Regression models developed show that, as long as the EMC is kept below 15%, a temperature of up to 37°C can be allowed without any visually detectable discolouration.     

中国紫胶虫生活史及其胶表物候

中国紫胶虫（Ｋｅｒｒｉａｃｈｉｎｅｎｓｉｓ）与其它胶蚧一样，均隐匿在其胶被内生长发育，外观难以看到各虫龄期的体形特征。用图表形式把各虫龄期及其相关的泌胶形态和冬夏两代各自所需无数标出，即可清楚看出该虫生活史、生活周期及各发育阶段期间的变化和关系。同时，列出各虫龄期特征检索表，便于在科研与生产中应用。