共查询到16条相似文献，搜索用时 140 毫秒
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云南铁杉干燥过程中变色的控制 总被引：6，自引：0，他引：6
云南铁杉在干燥过程中的变色问题是困扰许多木业企业的一个技术难题。笔者通过近几年的研究和实践 ,从其木材组分入手 ,分析了在干燥过程中云南铁杉变色的原因 ,制定了减轻变色程度的干燥工艺措施 ,使铁杉干燥过程中的变色率降至 10 %以内 ,其质量达到国标规定相应的技术指标 相似文献
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木材干燥 第5讲 锯材干燥缺陷及预防 总被引：3，自引：0，他引：3
木材由各种不同的细胞组成,细胞中又含有水分和化学抽提物,在贮存和干燥过程中会受到周围环境及真菌、细菌的影响或侵袭;又木材是各向异性体,在干燥过程中会产生干缩,且不同方向的干缩数值是不同的;再有锯材干燥过程中,断面上的含水率分布是不均匀的,内外层的干缩也是不均匀的;加之木材构造本身的缺陷等等;因此,锯材贮存和干燥过程中可能会产生种种缺陷,从而引起锯材的降等损失。其主要缺陷有:变色、开裂、翘曲、皱缩和终含水率不均匀。 相似文献
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根据俄罗斯产云杉木材的特点,采用常规室干的方法,对其40 mm厚锯材的快速干燥工艺进行初步探讨,并提出可供木材干燥生产参考的干燥基准,有效地提高木材干燥效率并防止变色. 相似文献
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原木板材经过干燥之后，不仅能防止木制品翘曲、扭曲、开裂、变形、变色等现象，而且木材的一些物理力学性能也能得到相应的提高。在实践生产过程中，本公司采用的是强制循环热空气为介质的干燥窑，对４０毫米厚的重娑罗双板方进行干燥处理。重娑罗双又名“沉水梢”木材强度大，气干密度高。主要用于重型地板，拼花地板，公用家具等。常规的干燥标准，由于干燥初期为低温高湿状态，从而引发①干燥周期较长的缺陷。②容易出现霉菌变色现象。因此在不影响干燥质量的前提下，笔者采用了间歇干燥工艺进行干燥，即干燥初期采用高温高湿，干燥中后… 相似文献
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通过化学试剂与木材中木质素、抽提物等成分发生反应,可以改变木材的颜色,从而达到对木材表面修饰的目的。以氯化亚铁(FeCl2)为变色剂,通过浸渍的方式获得了变色麻栎(Quercus acutissima)单板。利用正交试验研究了亚铁离子的质量分数、处理温度、处理时间以及干燥温度对麻栎单板变色的影响,获得了最佳处理工艺;利用色差仪对麻栎表面的色度系数进行了测试,并通过紫外漫反射光谱和红外光谱对麻栎变色的原因进行了探究。实验结果表明:经氯化亚铁溶液处理后,麻栎单板表面变为蓝黑色,颜色均匀,纹理清晰;影响麻栎单板变色的各因素主次顺序为氯化亚铁质量分数>干燥温度>处理温度>处理时间。氯化亚铁对麻栎进行化学变色处理的优化工艺参数为:氯化亚铁质量分数为1.0%、处理时间为10 min、处理温度为80℃、干燥温度为40℃。碱抽提可以去除麻栎单板表面大部分可以与铁离子发生变色反应的木质素或酚类物质,碱抽提后的麻栎不再发生明显的变色反应;麻栎与铁离子的变色反应,主要发生在木材的酚羟基和芳香环取代基上,木材中的酚类物质与铁离子络合反应是其变色的主要原因。 相似文献
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木材资源的多元化利用符合可持续发展国家战略方针。但木材在使用过程中会由于内部或外界因素产生变色,造成木材性能劣化,直接影响木材及其制品的质量。因此,研究木材变色机理以缓解木材缺陷具有现实意义。目前已有大量研究集中于木材随环境因子的变色规律,但仍存在环境条件考虑单一、化学结构变化规律不明确等问题。文中将变色木材的主体分为活立木和木材加工产品2类,分别对其变色的内因和外因进行总结;分析目前研究中存在的问题和未来研究方向,以期通过总结已知环境因子对木材变色的作用,服务于各因子协同作用下木材变色结果的研究,为减少木材变色缺陷和定向调控木材颜色提供研究思路,并为提高木材综合性能、拓展木材及其制品的应用范围提供参考。 相似文献
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防止兰考泡桐木材变色的初步试验 总被引：5，自引：0，他引：5
对多种化学药品配方防止兰考泡桐(Paulownia elongata)木材变色的效果进行了试验,并观测了处理前后材色的变化,探索到4种对防止变色有一定作用的配方。同时,初步观察了干燥条件和木材含水率对变色的影响,讨论了各种处理方法对防止兰考泡桐材变色的适用性。 相似文献
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GaoJianmin ZhangBiguang ChangJianmin 《中国林学(英文版)》2004,6(2):50-55
Buerger maple (Liquidambarformosana Hance) is a kind of wood that is easily discolored. This paper tries to obtain satisfactory color and a broad prospect in the utilization of buerger maple by induced discoloration. The authors analyze the mechanism of induced discoloration of buerger maple based on the analysis of visual physical parameter, the infrared spectrum (IRS) and the scanning electron microscope (SEM) under different drying conditions. The result shows that it is feasible to induce discoloration during the drying process. The wood color tends to be red and fuscous during inducing discoloration of buerger maple.The induced discoloration mechanism is: 1) the high temperature and humidity accelerates the oxidation reaction of polyphenol,leuco-fancy pigment and tannin, which changes the wood color to red; 2) the hydroxy (-OH) is oxidized and the carbonyl (-C=0),carboxyl (-COOH), ester and ketone groups form during the high temperature steaming, which results in wood piece discoloration. 相似文献
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In conventional drying, sawn birch (Betula sp.) timber darkens and reddens from the inside while the layer a few millimetres under the yellowish surface remains light in color. Lack of information concerning the chemical basis of the discoloration hinders the development of a reliable solution for this problem. In this study, the role of soluble proanthocyanidins in discoloration of birch wood was investigated because the polymerization and oxidation of these compounds are known to yield insoluble reddish compounds. Different periods of log storage affected the synthesis of soluble proanthocyanidins during conventional drying. Concentration of proanthocyanidins also correlated with changes in the color of birch wood. Discoloration appeared differently in conventionally dried and vacuum-dried wood, which indicates that the discoloration mechanism in these drying methods may differ chemically, and/or the compounds that take part in discoloration may be different at different drying temperatures. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):179-191
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. 相似文献
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泡桐材变色类型的确定及变色真菌的鉴定 总被引：10，自引：0，他引：10
对泡桐材变色类型的研究表明,泡桐材变色存在着真菌变色。同时从新伐的泡桐木材中分离出两种真菌,经鉴定是链格孢菌和一种根霉菌,这两种真菌可引发泡桐木材变色。 相似文献
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《Wood material science & engineering》2013,8(2):178-184
AbstractBlack alder wood has a great potential for more wide-spread use in the woodworking industry. This study describes the colour changes that appeared the first few hours after cutting thin veneer sheets from fresh, unseasoned black alder wood. CIELab coordinates were recorded for 50 spots at time intervals from 0 to 140 minutes exposure of the fresh-cut surfaces. The most pronounced change was increased lightness developing from 20 to 60 minutes after cutting. A model for total colour change as function of exposure time was developed. Redness of veneer sheets increased only slightly, i.e. the expected transfer to orange discoloration of the surface did not occur. The reason for this was probably that part of the free water in the wood was squeezed out during veneer production. The findings of this study give useful information about the colour change that appeared directly after veneer cutting, advising to avoid excess water on wood surface and ensuring quick surface drying. 相似文献