Investigation On Warp Foam Sizing Based On Snailase Pretreatment

Warp sizing process was an essential process which was to ensure the efficiency of weaving process,the quality and grade of finished product,it was also the significant process of the textile industry energy and resource consumption.At present,the traditional warp sizing method had many problems such as high slurry permeability,high sizing rate,large energy consumption and other serious pollution.The development of new warp sizing method to solve the problem of the traditional warp sizing method were meaningful.Foam sizing was a new method for the warp sizing by using foam as a medium,which can significantly reduce the pulp and energy consumption while maintaining the same quality of the sizing.However,due to cotton fiber surface water-resistant epidermis of the cotton yarn which was not easy to be wetted,the slurry bubble was difficult to penetrate the internal part of the cotton yarn.Moreover,in the sizing process,as the foam and cotton yarn contact time was very short,the performance of slurry foam and sizing processes would directly affect the sizing performance.In order to overcome the adverse effect of the wetting performance of the above-mentioned cotton yarn,this paper focused on the snailase which were rich of cellulase and pectinase that can remove the cellulose impurities and pectin composition that on the surface of the cotton fiber,and to a certain extent reduce the cotton wax which thereby enhanced the wetting performance of the cotton yarn.A dynamic sequence image was proposed to replace the traditional method that using sizing section to calculate average film thickness,yarn unevenness and size penetration and this paper used this dynamic method to study the influences of snailase pretreatment on the average film thickness,the yarn unevenness and the size penetration.The effects of the treatment conditions on the sizing rate,breaking strength and abrasion resistance and the influence of hairiness index were studied,and the optimization process of snailase pretreatment was optimized by response surface method.After pretreating with snailase,the cotton yarns were foam sized and optimized by three step experiment design method.Firstly,the physicochemical properties of cotton yarns by snailase pretreatment were investigated before sizing process.For comparison,sodium hydroxide(NaOH)solution,which was commonly used to pretreat raw cotton yarns,was also conducted to obtain control sample.Raw cotton,snailase-pretreated and NaOH-pretreated yarns were respectively analyzed by Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and X-ray diffraction(XRD).The SEM results showed that the cotton fiber pretreated by snailase presented a smoother surface.By FTIR,it was found that the ester group characteristic peak intensity of NaOH-pretreated yarns was decreased while the ester group characteristic peak of snailase-pretreated yarns was vanished.XRD results suggested that the crystallinity degree of NaOH-pretreated yarns decreased dramatically more than that of snailase-pretreated yarns.Then,effects of snailase pretreatment on pectin and wax removal percentage,wettability and breaking strength loss,weight loss of cotton yarns was studied respectively.After different conditions of snailase pretreatment,the maximum of pectin and wax removal percentage were 72% and 29%;wicking height reached to 7.6 cm;weight loss and breaking strength loss of cotton yarns respectively were up to 3.83% and 2.96%.Results revealed that snailase pretreatment not only effectively enhanced the wettability of cotton yarns through the hydrolysis of snailase,but also barely affected yarn strength.Secondly,a novel dynamic method were proposed to measure the sized-yarn properties including film thickness,sized-yarn evenness and size penetration rate based on yarn sequence images captured from a moving yarn.A method of dynamic threshold module was adopted to obtain threshold for segmenting yarns in the sequence images.K-means clustering algorithm was applied to segment pixels of the images into yarn and background.To further remove burrs and noise in the images,two judgment templates were carried out to extract information of yarn core.The film thickness,sized-yarn evenness and size penetration rate were measured based on the yarn core of each frame in sequence images.In order to compare with the experimental results of the dynamic method,the yarn properties of the same samples were tested by static and artificial testing respectively.Results revealed that the proposed method could be efficiently and accurately detect the film thickness,sized-yarn evenness and size penetration rate without artificial.The film thickness was greater than 3 ?m when the cotton yarn processed by snailase.Size penetration raised with the increase of the pretreatment conditions and then tended to stabilize,the maximum value was about 21.9% and sized-yarn evenness reduced to 4.72%.Thirdly,effects of different snailase pretreatment conditions(snailase mass concentration and treatment time)on sizing rate,enhancement rate of breaking strength and abrasion resistance and hairiness reduction rate were studied.The interaction between two pretreated conditions was analyzed by response surface method via central composite design.The pretreated conditions were optimized and got the optimum level.In the range of 0-15 g/L,the sizing rate of the warp yarn increased with the improvement of the quality of snailase.In the range of 15-25 g/L,the increase of the sizing rate decreased and tended to be 9%,the processing time increases from 2 min to 8 min,and the sizing rate increased significantly.With the increasing of the snailase mass concentration and treatment time,the enhancement rate of breaking strength increased first and then reduced and breaking strength enhancement rate was up to more than 50%.With the increase of the treatment conditions of snailase,the reduction rate of hairiness can reach up to 90%.The increase of wear resistance increases as the increase of mass concentration and the maximum was 97.2%.The snailase-pretreated conditions were optimized by using the central composite experiment design.When the snailase mass concentration as 22.3 g/L,the treatment time was 11.1 min,the response value was 96.2%.Finally,this paper investigated the process optimization of foam sizing for snailase-pretreated yarns.Effects of major foam-sizing process factors including size concentration,blowing ratio,foam temperature,stirring speed,foam velocity,squeezing pressure and drying temperature were studied on the hairiness(more than 3 mm)and abrasion resistance of foam-sized yarns.The combination of Plackett-Burman,steepest ascent path analysis and Box-Behnken design were adopted to optimize the foam-sizing process of cotton yarns.Results revealed that size concentration,blowing ratio and squeezing pressure were significant factors that affected the hairiness and abrasion resistance.Optimum hairiness and abrasion resistance were obtained when the cotton yarns were sized at size concentration of 18.2%,blowing ratio of 5,and squeezing pressure of 0.59 MPa respectively.The observed values respectively were 96.7%,132.8%.Raw cotton yarn,prewetting processed and snailase pretreated cotton yarns were respectively foam-sized under the same parameters,the experimental results proved that the snailase pretreatment can effectively improve the sizing performances.