摘要
染整加工是整个纺织工业中耗水量最大的产业。传统的染色方法以水为介质,染色后用水清洗,耗水量大,使用的化学品多,治理困难。所以,从源头防治污染,开发绿色染整加工技术,寻求少水或无水染色工艺成为染整领域的发展方向。
超临界二氧化碳流体染色(SCFD)是一种新型的无水染色技术。与传统的染色方法相比,超临界二氧化碳流体染色具有下列优点:真正实现了无水染色,彻底消除了印染废水的产生;降低能耗;印染加工中无需使用助剂,如用分散染料染涤纶可省去分散剂,匀染剂,净洗剂等化学品;超临界二氧化碳染色具有较高的上染率和良好的匀染性;残余的染料可以回收使用,染料利用率大大提高;染色时间短,染色后不必进行还原清洗;二氧化碳无毒,容易获取,且二氧化碳可循环使用,不会带来“温室效应”。
所以,超临界二氧化碳流体染色是一种极具发展前景的染色技术,符合环境保护的潮流。在该领域进行系统的研究,有助于将此技术推向实用化,产业化。
为开展SCF染色的系统研究,本实验室研究和设计制造了我国首台超临界CO_2流体染色实验室设备。为保证染色均匀性,该设备采取系统外循环方式,该设计不仅提高上染效率,也符合实际生产需求,是一种缩小的生产设备模型。
在此设备上,研究了超临界CO_2染色时不同的温度、压力、时间条件等工艺参数对染色性能的影响规律,当温度高于110℃,染料对纤维的上染明显提高。在温度保持恒定的情况下改变染色压力,随着压力的升高,染料对纤维的上染明显提高。但达到一定的压力(20MPa)后,继续提高压力,染料对纤维的上染不再明显改善。对于分散蓝79在超临界CO_2体系中染色,当染色温度为120℃~130℃时,染60min,上染已接近平衡。
东华大学博士论文
通过对分散染料在超临界二氧化碳体系的动力学研究,并和水介
质中染色的相关理论进行比较,得出染料在该体系中不同温度条件下
对涤纶纤维的扩散系数。根据An五enius方程推出染料在超临界二氧
化碳体系中向纤维扩散的表观活化能为67.47Jln101。在水介质中染料
在纤维中扩散的表观活化能为187.02Jh刀01。表明染料在水介质中向
纤维中扩散的能阻比在超临界C认介质中向纤维中扩散的能阻大得
多,水介质中染色对温度的依赖性比在超临界coZ介质中大。
本文还讨论了超临界Cq染色时不同的温度、压力条件对染料的
聚集态结构及性能的影响。采用了与染色同样的条件,研究了超临界
Cq染色时染色条件对纤维形态结构及性能的影响。通过X谢线衍
射、DSC、SEM、IR等手段研究了染料的聚集态和纤维形态结构的
变化。结果表明,染料的晶型没有发生变化,随着温度和压力的提高,
染料的熔点和结晶性能提高;纤维的晶体结构也没有发生变化,结晶
度有所下降,熔点基本上无变化,超临界Cq处理使低聚物向纤维表
面迁移,随着处理温度的提高,纤维表面的齐聚物明显增多,但纤维
表面未受损伤,其化学结构没有发生变化。
通过以上系统研究,为超临界C02染色,染料的选择、最佳工
艺条件的确定提供有效的理论依据,对该项新技术的应用将具有指导
意义。
Water is increasingly being recognized as a valuable raw material, the availability of which is not unlimited, and must be protected by appropriate legal measures. Up to the present day, the dyeing of textiles depends on water as solvent or as transport medium for the dyestuffs. Take synthetic fibers as an example, polyester fabrics, which are dyed with disperse dyes, require chemical auxiliaries such as surfactants, dispersing agents, etc., in the aqueous dye liquor, owing to the low solubility of dyes in water. However, these auxiliaries and unused dyestuffs still remain in the dyeing liquor after dyeing, and cause pollution. The waste water problem is, therefore, one of the most urgent issues of the textile finishing industry.
This is where the idea of dyeing in supercritical carbon dioxide comes from. Dyeing with supercritical carbon dioxide was developed to completely avoid the use of water during dyeing, thus creating no pollution. This novel technique offers many additional advantages including: complete elimination of water pollution; energy savings in drying textiles; a high degree of dye levelness and exhaustion; any residual dyestuff is easily recovered; dyeing in supercritical system requires shorter time; for PET, no aftertreatment such as reductive washing is required; carbon dioxide is nontoxic and easily obtained, and it can easily be recycled in a dyeing process.
A set of dynamic supercritical carbon dioxide dyeing equipment was successfully designed and constructed in this lab.
The effect of variables, such as temperature, pressure, dyeing time etc, to the uptake (measured as K/S) of PET fabrics was studied. It was found
that after the dyeing temperature reached 110℃, the dye uptake increased significantly, and it increased initially on increasing the pressure to 20 MPa, but increased very slowly after 20 MPa. The dye uptake approach equilibrium after dyeing 60min in supercritical carbon dioxide at 120~130℃ with C.I. Disperse Blue 79, the fastness of the dyed PET fabric was very good. Supercritical CO2 dyeing had no significant influence to the strength of PET fabric.
The diffusion model of the dyes to PET fabric in supercritical CO2 was obtained. The diffusion coefficient and the activation energy of the dye in PET fabric in supercritical CO2 and water were discussed respectively (the activation energy of the dye in PET fabric in supercritical CO2 was 67.47J/mol and that of the dye in PET fabric in water was 187.02J/mol),
The PET fabrics and the dyes were treated under model supercritical CO2 dyeing conditions. X-ray diffraction, differential scanning calorimetry, Scanning electron microscopy, infrared spectrum and so on were used to characterize fiber and dyes morphology, properties and structure. It could be concluded that the chemical structure of the PET fiber was not influenced by supercritical CO2, the crystalline forms of the dye and PET fiber did not change. However, the crystallinities of the dye and the fiber were affected by treatment conditions in supercritical CO2, the melting temperature of the dye increased on increasing the pressure and temperature and the melting temperature of PET fabric had not any changes on the whole.
引文
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