| The history of cotton textiles is long-term,it has accumulated a lot and covers a wide area.Nowadays,it is still a large industrial body.Since the 90 s of the last century,color-spun cotton fabrics have appeared gradually,and have been listed on the market in large quantities.Their products are soft,full-colored,with a strong sense of depth and feel.In particular,the appearance of pockmarks is unique and popular with the public.However,due to the physical and chemical effects such as high temperature,impregnation,scouring,and coloring,the cotton fiber has undergone changes in its structure and properties,such as strength,length damage,and compaction of fiber aggregates,and combing during spinning.Difficulties or changes in drafting,twisting,etc.,and spinnability are different from those in the past.From the historical literature,it can be seen that most of the predecessors' studies focused on the issues that should be paid attention to when the cotton fiber performance changes and process design before and after dyeing,and there is no in-depth study on the characterization of spinnability.Through analysis,it can be seen that the core of changes in spinnability before and after dyeing should be friction and cohesion,slipping and entanglement of fibers during drafting,and the combination of friction and cohesion in the bending,pulling,and releasing of fibers during carding.The traditional friction and cohesion test methods and indicators can reasonably verify the spinnability needs further verification and research.For this purpose,the following experimental scheme was designed: The three most common direct,reactive,and vat dyes for cotton fiber dyeing in the industrial sector were selected.Four dyeing programs were designed for each dye to understand the change in spinnability caused by dyeing.Degree and sensitivity of existing indicators,according to the test results given spinnability characterization recommendations.At the same time,the spinning process was performed under the same process conditions,and the indexes such as twist,strength,dryness,and hairiness of the produced yarn were tested,and the degree of correlation with the index of spinnability was compared.The results of the dyeing test showed that the cotton fibers were rubbed on the steel roller and the rubber roller.The friction after dyeing of each scheme was higher than that before dyeing,but the increase was not significant and the variation pattern was not thesame.When rubbing with the steel roller,compared with before the dyeing,the decrease of the friction coefficient after dyeing decreases with the increase in the quality of the tension clamp.The increase and decrease amplitudes between the different dyes of the same kind do not change significantly,and the difference between different dyes decreases slightly.There are changes,in which the range of reactive dyes is relatively stable,followed by direct dyes,and vat dyes have the most obvious changes;when compared with rubber rollers,the decrease in the friction coefficient after dyeing is the first decrease after the dye tension is increased compared with that before dyeing.As for the different dyes with the same kind of dye,the change rate of increase or decrease is not obvious,and there is little change in the increase or decrease between different dyes.The change range of vat dyes is relatively stable,followed by direct dyes,and the most obvious is the change of reactive dyes.It was found that all of the frictional solutions were improved after dyeing than those before dyeing.However,the changing rules were more complicated and the changes of the dyeings after each program were not obvious.Looking at the cohesion performance,the cohesion force of each scheme after dyeing is much higher than that before dyeing.The increase rate of different dyes of the same kind is not large;the increase range of different dyes is different,the increase rate of reactive dyes is about 6 times smaller,and it is relatively stable,followed by vat dyes,about 6-8 times,and direct dyes increase.The largest,about 7-8 times.On the whole,the increase rate of the friction coefficient is far smaller than the cohesion force,that is,the cohesion force has a higher degree of discrimination and sensitivity.Through the comparative analysis of the test data,the following recommendations are drawn: The sliver has a wide adaptability and data stability when measuring the cohesion force with a gauge length of 150 mm.The number of test times can reach discrete stability and the tensile speed is 200mm/min is appropriate.The index of spinnability expresses cohesion,cohesion length and color-to-color cohesion ratio(ie,the ratio of cohesion after dyeing to cohesion before dyeing,which is the new indicator proposed in this paper).The joint characterization of the three indicators is appropriate.The rate of change before and after reaction dyeing can also be expected to influence the spinning process.Spinning test results show that compared with before dyeing,the twist of fiber spinning after dyeing becomes smaller,indicating that the twisting efficiency is reduced;the strength is increased,not very obvious,and the strength may be increased if thetwisting degree is the same The higher point;unevenness of strips became larger,indicating that the control of the sliding state during the drawing of the fiber was strengthened,and the fluctuation of the dyeing effect caused by the poor control of the dyeing conditions also had a certain influence on the strips;the increase in hairiness indicated the fiber's The antistatic capacity decreased and the flexural rigidity increased.Through comparative analysis,it was found that the above-mentioned fluctuating relationship between the three indexes of spinnability and the measured results of the yarn is relatively linear.In summary,cotton fiber color spinning by measuring its cohesion force,cohesion length and dyeing cohesion ratio,can effectively reflect its spinnability,and has a significant significance in guiding the production and design process. |
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