Low/non Ammonia Alternatives With High Color Performances Instead Of Urea And Its Mechanism In Reactive Printing

Among the dye printing,reactive printing takes up a larger proportion due to bright color,good color fastness,soft handle as well as the increasing application on new types of fibers.Traditionally,10?20 wt % urea are needed in the reactive printing paste to achieve the moisture adsorption,swelling of fiber and dye solubilization,which ensures excellent surface color and fine pattern of the printed fabrics.However,the application of large amount of urea will make the ammonia nitrogen content in the printing and dyeing wastewater extremely high,causing a great burden on the ecological environment.Reactive dye urea-free printing technology is the development trend of printing industry.However,the existing urea substitutes on the market still have a gap with urea in the surface color yield of dark printing,sensitive color printing and viscose printing.It is difficult to fully replace urea and can only reduce the ammonia nitrogen content in printing wastewater to a certain extent.In this work,different functions of low/no ammonianitrogen auxiliaries are compounded for the printing of natural fiber fabrics,and strive to make the printed fabrics have printing performance equivalent to that of urea.The specific research content and results were as follows:(1)Research on the micro-mechanism of the hygroscopicity,swellability and solubilization performance of printing auxiliariesA complete set of evaluation methods for the hygroscopicity,swellability and solubilization performance of printing auxiliaries were established.The alcohol,amides and polyoxyethylene auxiliaries with different structures were selected to evaluate their hygroscopicity,swellability performance of viscous fiber and cotton fiber and solubilization performance of reactive turquoise K-GL.The results showed that for hygroscopicity,urea was the best,followed by glycerol,and1,3-propanediol was the worst among different types of additives.The more polar groups contained in the auxiliary,the more favorable it is for the auxiliary to bind water molecules;if the auxiliary can form intermolecular hydrogen bonds,it is not easy to combine with water molecules,resulting in weaker hygroscopicity.For the ability of swelling viscous fiber,1,4-butanediol was the best,and PPG-400 was the worst;for the ability of swelling cotton fiber,1,4-butanediol was the best,triethylene glycol was the worst.The better the hygroscopicity of the additive,and the smaller the molecular weight,the more conducive to the swelling of natural fibers;on the contrary,the worse the hygroscopicity of the additive,and the larger the molecular weight,the less conducive to the swelling of natural fibers.The amides had better properties for the dissolution of reactive turquoise K-GL,while the alcohols and polyoxyethylene are not ideal.The amide group in the amide auxiliaries can hydrogen bond with the-NH-in the dye,which was beneficial to depolymerize the dye aggregates and increase the solubility of the dye.(2)Design and development of special low/no ammonia-nitrogen auxiliary system for reactive printingThe optimized low/no ammonia hygroscopic components glycerol,swellability components1,4-butanediol and solubilization components caprolactam were compounded to prepare a series of low/no ammonia-nitrogen urea substitutes,and evaluated for their printing effect in viscose and cotton fabrics.The results showed that in the influence of urea substitute on the printing performance of fabrics,the moisture absorption performance of the auxiliary occupied the dominant factor,followed by the swelling ability of the fiber,and the third was the solubilization to the reactive dye.In the viscose fabric reactive turquoise K-GL dark color printing,the color performance of low ammonia-nitrogen compound additives GBC631 was higher than that of the commercially available urea substitute 391-H,which was slightly lower than that of urea;The color performance of nitrogen-free additive GB55 was higher than that of 391-H,which was close to urea,and it can obtain good surface color yield and fine pattern in reactive red,orange,blue and black dye printing.In the reactive turquoise K-GL dark printing of cotton fabrics,the color performance of low ammonia-nitrogen compound additives GBC523 was significantly higher than391-H,which was close to urea;The color performance of nitrogen-free additive GB28 was much higher than 391-H,even slightly higher than urea,and it can obtain good surface color yield and fine pattern in reactive red,orange,blue and black dye printing.(3)Printing performance of nitrogen-free high color yield additive in reactive printingThe printing performance of nitrogen-free GB55 with high color yield in reactive printing was discussed.And the feasibility and application potential of GB55 additive system to replace urea were also studied.The results showed that the ability to swell viscose fibers of GB55 was superior to that of urea.When the dosages of GB55 were within 8?10 wt % in the printing paste,color yield of GB55 on viscose fabrics drew near to that of urea and higher than that of 391-H.In viscose printing of reactive blue dyes with different shades as well as different structures,color performances of GB55 were also close to those of urea and higher than those of 391-H.Furthermore,GB55 can obtain good printing effects in deep printing with Reactive Turquoise KGL on different fabrics.Compared to urea,the contents of ammonia-nitrogen and total-nitrogen in the printing wastewater using GB55 greatly reduced,which was of great significance for lowering ammonia-nitrogen emissions in the printing industry.In this paper,through the evaluation method of the hygroscopicity,swellability and solubilization of printing additives,glycerol with high hygroscopic properties,1,4-butanediol with high ability to swell fiber,caprolactam with high solubility promoting properties were optimized.For increasing the surface color yield of viscose fabric,a special ammonia-free GB55 for reactive printing with high moisture soluble swelling properties was developed.Compared with 391-H,the ammonia-free GB55 can significantly improve the color performance of viscose fabric,and was close to the level of urea.GB55 was a green and environmentally friendly cleaning printing additive,which had good social and environmental benefits in the production process of reactive dye printing.