薄鞘高包覆涤纶/棉包芯纱的结构控制及其工艺

Structural control and spinning technology of highly wrapped core-spun yarn with thin sheath

为探究高包覆包芯纱的临界包覆率实现不露芯的包覆效果,采用低比例棉纤维包覆7.78 tex涤纶低弹丝制备出高包覆率包芯纱,且截面接近理想结构的涤纶/棉包芯纱,并进一步探讨外包棉纤维的临界比例,以及纱线结构与包覆率、棉与涤纶比例之间的关系。实验以5%为梯度不断减少外包棉纤维含量共纺制8组包芯纱,并通过数码显微系统表征纱线包覆率、截面结构等特点。结果表明:当外包棉纤维比例为53%时,包芯纱包覆率还保持在87.5%,此后包芯纱包覆率低于85%出现大面积露芯;随着外包棉纤维含量梯度化减少,包芯纱包覆率降幅呈三段变化,由开始的0.3%变化为4%,最后在52%的比例时降幅突增为9.4%。不同比例涤纶与棉纺制的包芯纱截面偏心度平均变化范围为8.8%~11.2%,实现了包芯纱结构的稳定控制。

Objective The wrapped effect has always been the core indicator in the market to judge the quality of the core spun yarns.In the market,the number of the wrapped fiber is always more than 80%to achieve the core filament being wrapped.The difficulty in achieving good wrapping effect lies in controlling the center position of the core wire.It is of great theoretical significance and application value to achieve high wrapping effect of yarn based on low outer fiber ratio and stable control of yarn structure,thereby improving the multi-component advantage of core yarn.Method To achieve high yarn wrapping effect and structural stability,this research proposed a solution by installing a filament control device to adjust the spinning process and parameters.Low-elastic polyester filament with a linear density of 7.78 tex as the core yarn,cotton roving with different quantities of as wrapping fibers were used to spin cotton/polyester core-spun yarn by ring spinning.The critical wrapping ratio of core-spun yarn was explored.The relationship between the structure of core-spun yarn and the wrapping rate was analyzed.The concept of yarn section eccentricity was introduced,and the structure stability of yarn was characterized by combining yarn coverage rate and longitudinal appearance morphology.Results The relative position of the polyester filament and cotton roving was controlled by the installed a filament positioning device.The component ratios of polyester filament and cotton roving in 8 sets of core-spun yarns are 75/25,70/30,65/35,60/40,55/45,53/47,52/48,50/50;The density of core-spun yarn is 31.8,25.5,21.6,19,17.4,16.5,16,and 15.7 tex,respectively.50 images were collected for each group of yarn with 100 times magnification,and the obtained image was binary-processed by Ostu algorithm to calculate the yarn coating rate.Compared with other binary processing methods,the Ostu algorithm had the smallest error probability and higher accuracy.When the component ratio of cotton roving was 53%,the coverage rate of core-spun yarns remained at 87.5%.When the component ratio of cotton roving was less than 53%,the coverage rate of core-spun yarns was lower than 85%and a large area of core polyester was exposed.It is concluded that critical coverage ratio of core-spun yarn was when the component ratios of polyester filament and cotton roving was 53/47.The average variation range of eccentricity of core yarn section under different polyester-cotton ratios was 8.8%~11.2%.The characterization of section eccentricity,yarn coverage,and longitudinal appearance morphology verified the effectiveness of the spinning process adopted in this laboratory.Conclusion The experiment provides data support and characterization for the discussion of the critical coverage rate during spinning cotton/polyester core-spun yarn by ring spinning.The computer image processing method for calculating the core-spun yarn coverage rate was obtained,which is convenient to operate and accurate.In addition,the factors affecting the stability of core yarn structure are analyzed from the perspective of theory and spinning practice,and the stable control of core-sheath structure is achieved by adjusting the spinning process.