Research On Processing Technology And Performance Of Polypropylene/Standard Melt Spinning Spandex Knitted Fabric

In response to the ISO14001 environmental policy and to create a more resource-saving and environment-friendly enterprise,Melt spinning has gained widespread attention and become a hot spot for major manufacturers to compete and invest with the advantages of low equipment investment,short production cycle,simple production process,high output,low cost,especially no pollution.With the continuous improvement of the requirements of the Chinese government for energy saving and emission reduction,melt spun spandex technology is expected to become the future direction of spandex development due to its economical and environmentally friendly production process and excellent product performance.In this thesis,the characteristics of the 22.2dtex standard melt-spinning spandex(hereinafter referred to as melt spandex)filament produced by Flexcell of Su Zhou city and cryogenic dry spandex were firstly tested and analyzed.mainly including the tensile properties and elastic properties of the yarns.The results show that the comprehensive mechanical properties of melt-spinning spandex after improved spinning process are better.Moreover the low-temperature dry spandex's breaking strength,elongation at break and modulus are lower than those of the improved melt-spinning spandex,and the elastic recovery rate is better than that of melt-spinning spandex.At the same time,the thermal properties of the above-mentioned spandex samples were tested,namely the determination of DSC and the determination of the strength and elastic properties after heat treatment at different temperatures,to provide reference for the research of heat setting process of melt-spun spandex knitted fabric.Secondly,three batches of 22.2dtex melt spun spandex bare yarns of the same specifications were interweaved with 83.3dtex polypropylene colored yarns respectively.The weaving performance of melt-spun spandex was discussed,as well as its superior weaving process parameters on circular knitting machines.The results show that when the loop length ratio and spandex content is the same,the elastic recovery of fabric decreases as the loop length increases.When the loop length of the plating yarn polypropylene is constant and the loop length ratio between polypropylene and spandex is changed,the elastic recovery of the fabric is affected by both the spandex content and the elongation of the spandex.At the same time,the issues regarding the precautions in the knitting process of the 22.2dtex melt-spinning spandex and the forming quality of the spandex tube were proposed.During the knitting process,the density of the sample coiling is smaller,the bobbin is soft,and there are some defects such as overlapping wires,collapse edges and spoiled yarns.For the melt spinning spandex silk sample,the material of the feeding roller will also affect the success of weaving.Finally,this thesis discusses the finishing technology of woven polypropylene colored yarn/melt spun spandex knitted fabrics.Single factor and orthogonal experiment method were used to study the effect of heat setting temperature,heat setting time and fabric expansion rate on the heat setting effect of polypropylene yarn/melt spun spandex knitted fabric.And got the best heat setting technology of polypropylene colored yarn/melt spun spandex knitted fabrics:110?/65s-80s/3%-6%.At the same time,the properties of the blanks containing melt-spun spandex and dry-spun spandex knitted fabrics were compared to provide basis for the application and promotion of melt-spinning spandex and its fabrics.