| Polyester and Polyester/Cotton blends fabrics are dyed at high temperature and high pressure with weakly acidic dye-bath.Polyester fabric with disperse dyestuff dyeing,especially for deep color dyeing,in order to adequately remove the floating color and residue on the surface of the fabric,improve the dyeing fastness,often in need of reduction cleaning after dyeing,among them,the hydrosulfite powder,low cost,good cleaning result,simple operation,widely used in disperse dyestuff reduction cleaning after dyeing,but bad performance in the application process,it is powder,inflammable,explosive,easy to decompose,easy to release sulfur dioxide pollution environment,and will cause effluent BOD value increase,thus increase the difficulty of waste water treatment.In addition,the polyester fabric is usually under the condition of weak acid dye,hydrosulfite powder vatting under alkaline conditions,so you need drainage at the end of the dyeing,after reduction cleaning,rinse with glacial acetic acid neutralization for many times,complicated working procedure and large water consumption.In this paper,based on the mutifunctional post-rinsing auxiliaries,a new type of sulfonate-type water-soluble polyester compound with low molecular weight was synthesized.The compound has the similar structural unit like that of polyester fibers.It has a strong affinity with both dyes and fibers,which the fabric’s dyeing fastness can reach or even more than the traditional insurance powder reduction cleaning effect,and low water consumption,short process.In this paper,dimethyl terephthalate（DMT）,sodium dimethyl isophthalate-5-sodium sulfonate（SIPM）and ethylene glycol are used as raw materials to prepare water-soluble polyester target products by transesterification-polycondensation reaction.Different synthetic methods and process parameters were explored,and the optimized synthetic route was deter mined.According to the ratio of SIPM:DMT,8 low molecular weight water-soluble polyester products with different characteristics were synthesized.Their chemical structural were characterized by NMR,IR,GPC and the physicochemical properties were detected,such as solubility,melting point,thermal stability and so on.The synthesized polyester product was dissolved into an aqueous solution with p H value 8,and the HLB value,surface tension,particle size distribution and size averages,water contact angle,foaming ability and foam stability of the polyester aqueous solution were investigated respectively.The results show that the target synthesis structure was achieved.The water-soluble sulfonated polyester has lower melting point than that of the ordinary polyester and water solubility increased as the content of SIPM increased,which lower the surface tension of water,with good wetting and low-foam properties.The low molecular weight water-soluble polyester products were applied in the polyester dyeing process.The results showed that the dispersing,leveling and migration of disperse dye,low temperature dyeing ability,and floating color and residue on the surface of the fabric were improved.When the molar content of SIPM reached 30 %,the concentration of 3 g/L watersoluble polyester in dyebath has dye retardation and migration,and the ΔE between colored samples was reduced from 11.15 to 1.95,so it can be used as dye leveling agent or migration agent in the dyeing of polyester.When the molar content of SIPM was reached 40% it was helpful for lower dyeing temperature as dyeing carrier of polyester.The wash-off color fastness of polyester fabrics using SIPM-30% reached or even more than the traditional sodium dithionitebased reduction clearing process,as it could be alternatives for sodium dithionite powder.The optimized wash-off process was 1:20 liquor ratio,weakly acidic bath,80℃×20 min.The dosage of agent SIPM-30% was different depends on color shade of dyed fabrics.Based on economical the concentration of rinsing auxiliaries is 2 g/L,4 g/L,8 g/L respectively as light,light-dark and dark shade. |
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