【作者】 薛旭婷；

【导师】 何瑾馨；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2009， 博士

【摘要】 活性染料由于染色工艺成熟、色谱齐全、价格适中、色牢度较高等优点成为印染纤维素类纺织品的首选染料。但是,染色过程中活性染料在上染、固着的同时有高达20～40%的活性染料会发生水解,而不能与纤维素发生反应形成共价键结合,但其扩散和吸附性能与未水解活性染料相似,因此容易扩散进入纤维内部,并吸附其表面形成“浮色”;另外染深色时,吸附于织物表面的染料分子易形成多分子层式缔合物,产生“位阻”现象,又导致产生浮色。未固着染料的存在会降低染色织物的色牢度,这个问题在染色过程中无法有效解决,因此染色结束后必须通过净洗工艺除去织物表面的浮色以提高染色织物的色牢度。目前普遍采用水溶性高分子化合物或其与表面活性剂的复配物净洗染色织物上的浮色,并通过水溶性高分子化合物与浮色染料及织物纤维在净沈浴中作用的方式阻止洗脱的浮色对白底沾色。基于此方案,本论文以易生物降解的天然原料壳聚糖为修饰对象,通过引入羧甲基、氨基羧酸、羟基羧酸、内酰胺基、烷基的方式制备了N,O-羧甲基壳聚糖（NOCC）、乙二胺四乙酸酰化壳聚糖（ETC）、氮川三乙酸酰化壳聚糖（NTC）、柠檬酸酰化壳聚糖（CAC）、5-甲基吡咯烷酮壳聚糖（MPC）、异丁基壳聚糖（IBC）六种壳聚糖衍生物,研究了它们在活性染料染色棉织物净洗中的应用性能。研究壳聚糖衍生物的螯合、分散性和pH缓冲性能表明,含有羧基取代的衍生物具有较高的螯合、分散能力和pH缓冲能力,而取代基为内酰胺和烷基的衍生物分散能力尚可,但螯合能力较差;羧基含量越高,衍生物的螯合、分散力越强;对于相同结构的衍生物,较高的分子量具有较高的螯合、分散力,但分子量太高的衍生物螯合、分散力反而降低。研究壳聚糖衍生物的取代基、取代度、分子量对净洗效果的影响结果表明,引入羧甲基、氨基羧酸及羟基羧酸的壳聚糖衍生物的净沈性能高于引入内酰胺结构和烷基结构的壳聚糖衍生物;增加羧基的取代度可以提高净沈效果,但是羧基含量太高,增加了与染料分子之间的静电斥力,反而导致净洗效果降低;对于不含羧基的衍生物增加取代度也可以改善净洗效果;增加分子量可以提高净洗效果,分子量太高,导致壳聚糖衍生物在水中有效结合染料分子的量降低,从而使净洗效果降低。通过对NOCC与不同表面活性剂复配体系的研究表明,NOCC分子中的部分羧基与十二烷基二甲基甜菜碱（DDB）分子中的季铵基以静电力发生结合,使复合体系的表面张力增加,且临界胶束浓度也提高;NOCC的加入可以压缩十二烷基硫酸钠（SDS）离子头基的双电层,使复合体系的表面张力降低,临界胶束浓度减小;NOCC分子可以与十八烷基聚氧乙烯醚(C₁₈EO₂₀)分子间以氢键、范德华力等结合,使复合体系表面张力降低,临界胶束浓度增加;降低表面张力的能力顺序:NOCC-SDS＞NOCC-DDB＞NOCC-C₁₈EO₂₀。NOCC加入DDB、SDS、C₁₈EO₂₀三类表面活性剂中均可以增加体系对水解活性翠蓝KN-G（RBE21）的增溶能力,但是SDS体系的效果较差,低浓度下C₁₈EO₂₀的效果较好,高浓度下DDB效果较好。NOCC-表面活性剂复合体系用于净洗过程中,均是通过与浮色染料和染色织物两种途径发生作用,而且作用后经过水沈后均不会沉积在织物表面。抑制染料上染棉织物的能力:NOCC-C₁₈EO₂₀＞NOCC-DDB＞NOCC-SDS。NOCC-C₁₈EO₂₀协同作用的净洗效果较好,NOCC-DDB协同作用的净洗效果次之,NOCC-SDS协同作用的效果较差,这与NOCC-表面活性剂体系对水解RBE21的增溶顺序一致,这说明净沈剂对洗脱染料的增溶作用在净洗过程中起主导作用。通过研究不同结构水解活性染料对棉织物的吸附表明,对于具有相同活性基的活性染料,母体为铜络合偶氮、铜酞菁、蒽醌结构的水解染料对棉织物的吸附量较高;相对不含杂环结构的偶氮染料,含杂环结构单偶氮水解活性染料对棉织物的吸附量较高;相同母体结构的染料,取代基越复杂,染料分子越大,分子量越大,对棉织物的吸附量越大;均三嗪型活性染料水解后对棉织物的亲和力增加,而乙烯砜型活性染料在加碱前对棉织物的亲和力最低,加碱后变为最高,水解后亲和力又降低,这说明均三嗪型染料水解后可以增加染色织物浮色的净洗难度,而乙烯砜型水解后则可以降低净洗难度。通过壳聚糖衍生物抑制不同结构水解活性染料对织物的吸附研究表明,疏水相互作用在水解活性染料对织物的吸附过程中起主要作用,即要将水解染料从织物上洗除,主要应该通过增加染料在水中溶解度的方法;壳聚糖衍生物主要是通过静电力、氢键等有效地抑制洗脱染料对棉织物的吸附,而不是疏水作用力。通过研究膨润土负载季铵盐壳聚糖（CTA-CTS）在活性染料染色棉织物净洗工艺中的应用表明,膨润土负载CTA-CTS制备净洗剂的较佳工艺条件为:CTA-CTS与膨润土质量比1:5,CTA-CTS的取代度0.93,分子量为100.0 kDa;膨润土负载CTA-CTS的净洗机理主要是通过吸附作用破坏浮色染料在织物和水溶液中的分配平衡,使浮色染料不断向水溶液中迁移,直至达到新的平衡;膨润土负载CTA-CTS对活性染料染色织物的净洗可以达到目前常规净洗剂的净洗效果,而净洗残液的吸光度值和COD_Cr值接近常规值的1/10,可以降低废水处理的负荷。采用循环洗涤的方法,证明膨润土负载CTA-CTS可以降低净洗过程中膨润土在织物上的沉积。更多还原

【Abstract】 The consumption of reactive dyes is on the rise and is expected to remain so in the near future for their acceptable price,good color values and reasonably good fastness properties.However,the reactive dyes suffer the disadvantage of incomplete exhaustion and hydrolysis up to 20～40%during dyeing and hence there is considerable loss of dyes. Additionally,unreacted and hydrolyzed reactive dyes can adhere to the substrate physically decreasing the fastness,because the hydrolyzed dyes are usually similar to the original dye in diffusion and adsorption properties.When applying reactive dyes in full depths,especially inefficient reactive dyes,the effectiveness of fixation may decrease.As a consequence,in order to achieve optimum fastness,the resultant dyeings need to be thoroughly washed-off to remove the unfixed dyes.Water-soluble polymers have been frequently applied in the formulation of soaping agent in wash-off reactive dyeings,in order to inhibit the restaining of released dyes to cotton fabrics.For this scheme,chitosan,a natural and readily biodegradable material, was modified through the introduction of carboxymethyl groups,amino carboxylic acid, hydroxyl carboxylic acid,lactam groups and alkyl groups to prepare N, O-carboxymethyl chitosan（NOCC）,N-ethylenediaminetetraacetic acylated chitosan （ETC）,N-nitrilotriacetic acylated（NTC）,N-citrylated chitosan（CAC）,5-methyl pyrrolidinone chitosan（MPC） and N-isobutyl chitosan（IBC）,respectively.The six chitosan derivatives were applied to wash-off reactive cotton dyeings and determined the effectiveness in removing unfixed reactive dyes.By comparing the performances of these chitosan derivatives,it showed that the carboxyl substituted derivatives exhibited the higher chelation,dispersion and pH buffering,and the derivatives substituted with lactam and alkyl groups exhibited a general dispersion capacity but poor chelation capacity.For the derivatives with the same substituted groups,increase the molecular weight can strength their chelation and dispersion capacity,but the too high molecular weight leads to the decrease of chelation and dispersion capacity.The chelation and dispersion effectiveness of chitosan derivatives increased with the increase of degree of substitution values of carboxyl groups.Three problems associated with the use of chitosan derivatives in the wash-off process viz.,the substituted groups,degree of substitution and molecular weight,were investigated.The results indicated that the wash-off performance with the carboxyl substituted derivatives of chitosan was better than lactam and alkyl substituted ones. The wash-off effectiveness of chitosan derivatives increases with the increase of the degree of substitution of carboxyl groups,but the too high carboxyl contents lead to increase the electrostatic repulsion between dye molecules and chitosan derivatives and result in a lower wash-off effectiveness.For MPC and IBC,the wash-off effectiveness also increases with increasing the degree of substitution.The results from wash-off tests with different molecular weight of chitosan derivatives suggested that increase in molecular weight of chitosan derivatives can increase the wash-off effectiveness; however,the results also showed that too high molecular weight produced a sharp reduction in wash-off effectiveness because the amount of effective groups of chitosan derivatives to combine with dyes decreased.Surface tension studies on the interactions of different types of surfactants in the presence and absence of NOCC respectively,were also conducted.It was showed that the presence of NOCC slightly increased the surface tension and critical micelle concentration value of dodecyl dimethyl betaine（DDB）.This result can illustrate that electrostatic attraction between the molecules of NOCC and DDB exist,forming hydrophilic complexes soluble in the solution.NOCC acted as a polyelectrolyte increase the number of counter ions in the Stern and diffuse layers,screening the electrostatic repulsion between the head groups of SDS,which can illustrate the slight decrease of surface tension and critical micelle concentration value of SDS upon addition of NOCC. Octadecyl polyoxyethylene ether(C₁₈EO₂₀) and NOCC can bind to form hydrophilic complexes due to hydrogen bonding,which can account for the significant decrease of surface tension below critical micelle concentration and critical micelle concentration value of the solution containing NOCC.The surface activity acted in the order: NOCC-SDS＞NOCC-DDB＞NOCC-C₁₈EO₂₀.Spectroscopic studies on the hydrolyzed Reactive Turquoise Blue KN-G（RBE21） in surfactant solutions showed that upon addition of NOCC,synergistic solubilization by NOCC and surfactants on the hydrolyzed RBE21 was observed.In higher concentration,NOCC-DDB showed higher solubiliztion ability to hydrolyzed RBE21 than NOCC-C₁₈EO₂₀,and in lower concentration correspondingly less.However,the hydrolyzed RBE21 was slightly solubilized in NOCC-SDS micelles by adoption of the aggregate forms.In wash-off process,NOCC and surfactants acted on released dyes and cotton fibers and would not deposit on cotton fibers after sufficient wash with water.The effects of inhibiting hydrolyzed RBE21 from staining cotton fabrics were found to be in the order: NOCC-C₁₈EO₂₀＞NOCC-DDB＞NOCC-SDS.The synergy effects of NOCC and surfactants in wash-off tests showed that the wash-off performance was in the same order with solubilization effects.This result confirmed that the wash-off process of reactive dyeings with NOCC-surfactant complexes was dominated by solubilization effect.Investigations have been made of the adsorption of different hydrolyzed reactive dyes to cotton fabrics to establish key factors governing dye transfer in wash-off reactive dyeings.The results showed that for the reactive dyes with same reactive groups, possessing chromophores of azo-copper complex,copper phthalocyanine and anthraquinone,were found to be higher affinity for cotton fabrics.Heterocyclic azo dyes showed higher affinity to cotton fabric than other azo dyes.Adsorption to cotton fabric increased with apolar substituent on dyes,implicating entropic factors dominated the binding process.Dyes with triazine reactive groups tended to increase the adsorption to cotton after they were hydrolyzed,while hydrolysis was likely to be opposing contibutions for dyes with vinyl sulfone reactive groups.These studies help to illustrated that the hydrolyzed dyes with triazine reactive groups increased the difficulty of wash-off process,while the hydrolyzed dyes with vinyl sulfone reactive groups can easily be washed-off.The influence of sulphonate groups in different pH solutions showed that adsorption to cotton was strongly influenced by hydrophobic interactions.These studies help to highlight the role of solubilization effects in wash-off process.Chitosan derivatives were extremely effective at preventing adsorption of released dyes in washing bath to cotton and they tended to bind dyes more by electrostatic,polar or hydrogen bonding interactions rather than hydrophobic interactions.A kind of dye absorbent was prepared from the combination of N-hydroxypropyl trimethylammonium chloride chitosan（CTA-CTS） and Ca-bentonite and was employed as builders in wash-off unfixed dyes from RBE21 dyed cotton fabric.CTA-CTS loaded bentonite was studied by means of IR,XRD and SEM.The factors influencing wash-off effectiveness,including the amount of CTA-CTS and the achievable degree of substitution and molecular weight were investigated.The results show that the optimum weight ratio of chitosan to bentonite was 1:5,DS=0.93,Mw=100.0 kDa.The experiments demonstrated that the reactive dyeings washed with this absorbent can reach the soaping fastness level of ordinary soaping agent;meanwhile the residual washing liquor had ca.1/10 absorbance and COD_Cr values of ordinary ones.更多还原