Effects On The Performance Of Heat Welded Seam For Knitted Apparel

Seamless heat welding,as a new garment processing technology,eliminates the use of needle and thread.It uses thermoplastic adhesive tape to weld the garment pieces through the new electronic processing technology such as heat,laser and ultrasonic.It has been gradually applied to ordinary clothing.However,in actual production,the blindness of the compatibility between fabric and adhesive tape,the fuzziness of the range of processing parameters largely affects the bonding effect of the fabric,thus causing problems in the seams and affecting the wearing of garment.In this paper,seven common nylon-spun warp knitted fabrics with different yarn fineness,structure and blending ratio were selected as experimental fabrics.Four kinds of polyurethane tapes with different specifications and excellent elastic properties were selected and matched.Through pre-experiment,the level of various factors of heat welding parameters was determined,the temperature is 160?,170?,180?;the time is 20s,25s,30s;the pressure is 3bar,4bar,5bar,and the combination of welding parameters is nine kinds by orthogonal design.The properties of welding test of seam strength,peeling strength,elastic recovery and heat shrinkage was carried out on the heat welded knitted fabrics,and the experimental results were statistically processed by analysis of variance to explore the influence of fabric,tape and welding parameters on the seam performance.According to the analysis,the gram weight and thickness of the fabric are positively correlated with the seam strength,the gram weight of the fabric has a significant effect.The thicker the fabric,the greater the seam strength.The fabric weight is above 200g/cm²,and the seam strength reaches 900?1400N.The degree of influence of adhesive tape on the seam strength is J₃>J₄>J₂>J₁.The same material adhesive tape,the greater the thickness,the more adhesive.When the adhesive tape is fully melted,the stronger the seam strength of the welded knitted fabric will be.The tape J₁is the thinnest,and its seam strength is the smallest,which cannot meet the basic adhesion fastness;while the same thickness J₃,J₄,the thermoplastic polyurethane J₄is easier to melt than the ester polyurethane J_3.Under all process,the qualified rate of J₄compatible welded fabric is 100%.The welding parameters has significant influence on seam strength,and the influence degree is temperature>time>pressure.The seam strength will gradually increase with the increase of temperature,time and pressure,but the rising speed will slow down gradually.When the seam strength reaches the highest value,it will stop growing,and then the decline will occur.If the increase is made,the decline will be larger and larger.Secondly,the weight of the fabric is positively correlated with the peeling strength,the weight and composition have a significant effect.The greater the weight of the fabric,the greater the peeling strength.The peeling strength of the medium or lighter warp knitted fabric is mostly about 1?15 N/cm,while that of heavy fabric is4?25N/cm.In terms of adhesive tape,the peeling strength is basically the same as the seam strength,J₃>J₄>J₂.In terms of welding parameters,the degree of influence of peeling strength is temperature>pressure>time.The weight of the fabric is positively correlated with the heat shrinkage rate, the fineness of the yarn count has a significant effect.The greater the weight of the fabric,the worse the thermal shrinkage rate will be.The thermal shrinkage rate of the heavier fabric is-0.8?-0.25%,which is higher than the-1.5?-0.25%of the medium or light fabric.The type of tape has no significant effect on the heat shrinkage rate.The temperature has a significant effect on the heat shrinkage rate,and the heat shrinkage rate deteriorates as the temperature rises.For elastic recovery,the impact of heat welding on the elastic recovery of the fabric is small.Under the condition that the fabric is not damaged,the elastic recovery rate of the heat welded knitted fabric is higher than that of the original fabric,and the overall elastic recovery rate remains between 97%and 99%.Based on the above test results,the seam strength is the positive index and the absolute heat shrinkage rate is the negative index.The performance of heat welded seam for knitted apparel is evaluated by the Osculating value method.The result is:for thicker fabrics(200g/cm²or more),select tape J₄for compatibility.For medium or relatively thin fabric,select tape J₃for compatibility.In terms of welding parameters,the optimal welding parameters of J₄are:temperature is160?,time is 20 s,pressure is 3 bar;the optimal welding parameters of J₃are:170?,time is 25 s,pressure is 4bar.In this paper,through the research on the seam performance of heat welded knitted fabrics,provides a theoretical basis for the enterprises in the production of the heat welded knitted fabric,selecting the appropriate adhesive tape and fabric compatibility,selecting the appropriate welding parameters,so as to improve the quality of garment,enterprise production efficiency,reduce enterprise production costs.