【作者】 陈星；

【导师】 邓邵平； 兰从荣；

【作者基本信息】 福建农林大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 木材染色是提高低质速生材附加值的有效途径。但木材染色过程中仍存在染色深度不够、染色不匀等问题,预处理能够有效改善木材的渗透性能。本文以人工林杉木木材为研究对象,采用单因素法考察NaOH预处理各因素对木材抽提物含量、体积皱缩率和酸性大红3R染色材上染率和染透率的影响,并对NaOH处理后的木材再进行冻融循环处理,探究冷冻时间、解冻时间和循环次数对木材上染率和染透率的影响;在此基础上利用响应面法优化NaOH-冻融循环预处理工艺条件,并用单一酸性、活性染料及各自混合染料进行验证试验;通过场发射扫描电子显微镜（FE-SEM）和压汞（MIP）法分别观察和分析预处理前后木材微观和孔隙结构变化;最后探讨预处理对染色材耐光色牢度和耐水色牢度的影响,主要结论如下:（1）随着NaOH浓度增大、抽提时间延长和抽提温度升高,木材的抽提物含量增加,但体积皱缩率也明显增大,NaOH抽提处理后再经冻融循环处理可以进一步影响木材的上染率和各向染透率;与未处理材相比,NaOH处理和其再经冻融循环处理使最大上染率、纵向、径向和弦向染透率分别增大1.6、10.6、30.6、37倍和1.9、12.2、34.5、43.2倍。根据两种线性拟合结果,选择NaOH浓度、抽提时间、冷冻时间和循环次数为后续响应面优化试验的因素。（2）响应面法优化出NaOH-冻融循环预处理的最佳工艺为NaOH浓度0.42%、抽提时间24h15min、冷冻时间18h40min、循环次数2次。在此条件下木材上染率、纵向、径向和弦向染透率的预测值分别为8.90%、77.57%、48.29%、和27.45%,3次重复验证试验平均上染率、纵向、径向和弦向染透率分别为8.45%、76.63%、47.25%和26.46%,均与预测值差异不大,该模型合理有效;单一酸性、活性染料及其各自混合染料的染色试验以及吸水增重试验进一步验证了该工艺可靠。NaOH-冻融循环预处理材的FE-SEM观察发现,径切面管胞壁上的抽提物减少,纹孔清晰可见,弦切面上木射线薄壁细胞内抽提物被溶出,轴向管胞与木射线薄壁细胞发生分离;MIP法分析显示预处理后木材总孔体积和孔隙率较未处理材分别增加35.93%和4.75%。（3）经108h紫外光照后,NaOH预处理和NaOH-冻融循环预处理染色材色差均较未处理染色材有所减小,说明预处理能使染色材耐光色牢度有所改善;但耐水性试验表明预处理对其耐水色牢度的影响很小,FTIR分析显示NaOH处理使试样在1739cm^-1附近相关C=O消失,其余峰形基本未变化,这与预处理后染色材耐光色牢度和耐水色牢度变化相吻合。更多还原

【Abstract】 Wood dyeing is an effective way to increase the added value of low-quality raw materials.In the process of wood dyeing,there are still problems such as insufficient dyeing depth and uneven dyeing.The pretreatment can effectively improve the permeability of wood.The effects of various factors on extract content,volume shrinkage and dye-uptake and dye penetration rateof Acid Scarlet 3R dyed wood after pretreatment with sodium hydroxide were analyzed.The effects of freezing time,thawing time and cycles on wood dyeing rate and permeability were investigated.On this basis,response surface methodology was used to optimize the sodium hydroxide-freeze-thaw cycle treatment process,and single acid,reactive dye and their mixed dyes were used to verify the experiment.The changes of wood micro-structure and pore structure before and after treatment were observed and analyzed by field emission scanning electron microscopy（FE-SEM）and mercury intrusion porosimetry（MIP）.Finally,the effects of pretreatment on light fastness and water fastness of dyed materials are studied.The main conclusions are as follows:（1）With the increase of sodium hydroxide concentration,extraction time and extraction temperature,the content of wood extracts increased and the volume shrinkage rate increased.Compared with untreated wood,the maximum dye-uptake,longitudinal,radial tangential dye penetration rate increased by 1.6,10.6,30.6,37.0 times and 1.9,12.2,34.5 and 43.24time;after sodium hydroxide treatment and sodium hydroxide-freeze-thaw cycles pretreatment,respectively.According to the two linear fitting results,sodium hydroxide concentration,extraction time,freezing time and cycle times were selected as response surface methodology factors.（2）The optimal process of sodium hydroxide-freeze-thaw cycles treatment was optimized by response surface methodology.The process was sodium hydroxide concentration 0.42%,extraction time 24 h 15 min,freezing time 18 h 40 min and cycle times 2 times.The predicted values of dyeing uptake,longitudinal,radial,tangential dye penetration rate were8.90%,77.57%,48.29%and 27.45%respectively.The average dye-uptake,longitudinal,radial and tangential dye penetration rate of the three repeated validation tests were 8.45%,76.63%,47.25%and 26.46%respectively,which were not significantly different from the predicted values.Therefore,the model was reasonable and effective.The dyeing tests of single acid,reactive dye and their respective mixed dyes and the water absorption and weight gain tests further verified the reliability of the process.Scanning electron microscopy（SEM）of sodium hydroxide-freeze-thaw cycle treated wood showed that the extracts from longitudinal tracheid wall decreased in radical section,and the pits were clearly visible.The extracts from ray parenchyma cells were dissolved in tangential section,and the longitudinal tracheid walls were separated from ray parenchyma cells.Mercury intrusion analysis showed that the total pore volume and porosity of pretreated wood increased from 35.93%to 4.75%compared with untreated wood.（3）After 108 hour UV exposure,the color difference of dyed wood with sodium hydroxide and sodium hydroxide-freeze-thaw cycles were lower than that of untreated dyed wood,which indicated that pretreatment could improve the light fastness of dyed wood.The wash resistance test of dyeing materials showed that pretreatment had little effect on their water color fastness.The FTIR infrared spectrum showed that the carbonyl peak at 1739 cm^-1 disappeared of the sodium hydroxide-freeze-thaw cycles treated materials,and the other peak shapes were basically unchanged,which were consistent with the changes of light fastness and water fastness of the dyed wood after pretreatment.更多还原