Delay-curing Finishing Of Cotton Fabric Based On Liquid Ammonia Pretreatment

Cotton fabric is a soft and well-permeable fabric,which plays an important role in daily life and production,but it has the problem of easy wrinkling and deformation in use.These problems of cotton fabrics affect the wearability and bring many troubles in practical use.In view of these shortcomings of cotton fabrics,the current more effective process is to carry out non-iron finishing.Among them,the delay-curing is a non-iron finishing method that is conducive to obtaining a better setting effect of the finished garment.In the development of the delay-curing,the stability of the fabric during the storage and the improvement of the non-iron finishing effect are the key issues.The pretreatment can play a certain role in improving the non-ironing effect and storage stability.At present,there is a lack of research on the improvement of pretreatment in delay-curing.Liquid ammonia pretreatment has been proven to effectively improve fabric performance and non-iron finishing effect.The practical production of Lu Thai Textile Company usually chooses the mercerizing-liquid ammonia pretreatment.This work foucses on the pretreatment improvment based on the pretreatment from Lu Thai Textile Company.The effect of the modified pretreatment on the fabric performance and delay-curing effect is investigated.At the same time,the optimization of delay-curing is carried out based on the selected pretreatment and the mechanism for pretreating is further explored.The research content and results are listed as follows:First of all,based on the conventional mercerizing-liquid ammonia pretreatment,this work improved the pretreatment by reducing the speed of the liquid ammonia process,adding a liquid ammonia process,or replacing the mercerizing process with the liquid ammonia process.And the breaking strength,wrinkle recovery performance,whiteness,feel and style characteristics,moisture regain,moisture permeability,air permeability,moisture permeability and UV resistance of fabrics were tested.Characters of fabrics with and without improved pretreatment were comprared and the effect of the adjusted pretreatment was explored.Finally,it is concluded that fabric with the liquid ammonia-mercerizing-liquid ammonia pretreatment has the best overall performance,which not only has better breaking strength and wrinkle recovery performance,excellent moisture permeability and UV resistance,but also presents the softest and smoothest in hand feel.In addition,its drape,moisture regain,moisture permeability and air permeability are all the best.Secondly,the non-iron performance and storage stability of fabrics before and after the improving pretreatments were tested to get the proper pretreatment which is more suitable for the delay-curing.The improved pretreatment with liquid ammonia-mercerizing-liquid ammonia can not only offer the fabric an excellent and permanent ironing effect,but also can significantly improve the storage stability of the fabric during delay-curing.The wrinkle recovery performance of the fabric after curing is significantly improved,and the breaking strength and whiteness are better compared with the fabric obtained by original mercerizing-liquid ammonia pretreatment.Under the storage conditions of 80 ℃,40 ℃ and20 ℃,the stability of sensitized fabric with liquid ammonia-mercerizing-liquid ammonia pretreatment is better than that of other fabrics.The whiteness is always the highest during storage,and the change of wrinkle recovery angle and strength are the slowest.In addition,according to the changing trends of several fabrics during storage,it can be concluded that the sensitized fabric should avoid to be stored at high temperature to maintain its stability during the delay-curing.The storage time at 40 ℃ should be controlled within 28 days,and the storage time at 20 ℃ should be controlled within 60 days.Finally,on the basis of the delay-curing with traditional mercerizing-liquid ammonia pretreatment,single-factor experiments and orthogonal experiments were designed for exploring the proper delay-curing suitable for the liquid ammonia-mercerizing-liquid ammonia pretreatment.The factors that affect its non-iron performance were studied: the factors affecting the breaking strength after finishing are from large to small: curing temperature> curing time> resin concentration;the influencing factors of the wrinkle recovery angle after finishing are from large to small : resin concentration> curing temperature> curing time.And it is determined that the optimal delay-curing is: resin concentration 130 g/L;curing temperature 150 ℃,curing time 3 min.Using the optimized process,the obtained fabric exhibits better storage stability and non-ironing performance compared with conventional mercerizing-liquid ammonia pretreated fabric;the retention rate of breaking strength is increased by nearly 3%;and the wrinkle recovery angle is increased by 8.17°,which verifies the effect of improved pretreatment.In addition,the surface morphology,crystallization and chemical composition of the fabrics before and after curing were analyzed in order to characterize the mechanism of improved pretreatment towards fabric performance and the effect of the non-iron finishing.It is concluded that fabric with the improved liquid ammonia-mercerizing-liquid ammonia pretreatment not only has a more rounded and straight fiber shape,but also has less surface damage.After treating with the improved pretreatment,the amorphous area of fiber is increased,the chemical reaction ability is stronger,and the crystallinity after curing is improved more obviously.The type of chemical bond is basically unchanged before and after processing with modified pretreatment,and carbonyl groups are introduced into the fabric after curing.