Cold Pad-Batch Pretreatment And Whitening Whole Process Of Cotton Knitted Fabrics

In conventional one bath process pretreatment and whitening of cotton knits,high temperatures(110?),strong alkali,hydrogen peroxide,Scouring agent,stabilizer and fluorescent brighteners are necessary for the removal of cotton hulls,wax,pectin and whitening.However,the conventional process is of the characteristics of high energy consumption,high cost,serious sewage when obtaining extra-white fabrics.Cold pad batch technology is a process of green environmental protection,energy conservation with the advantages of short technological process,simple equipment and low energy consumption.The application of cold pad batch will be greatly improved with the development of knitted fabric from cylinder processing to open width processing.This topic studied the application of cold pad batch technology in the pretreatment and whitening of cotton knitted fabrics.The research was aimed to achieve energy conservation and green environmental protection when the knitted fabric whiteness and various indexes are equal to the conventional process with the process of cold pad batch.The topic was studied from three parts with cold pad batch,soaping after CPB and fabric setting.This research provided theoretical and technical support by the selection of CPB pretreatment and whitening process optimization for the application of workshop.Firstly,this paper explored the application of fluorescent brighteners and determined the suitable fluorescent brightener in the CPB pretreatment and whitening process with the cotton knitted fabric 20S/1 Interlock.Influences of the dosage of sodium hydroxide,hydrogen peroxide,cold batch assistant,fluorescent brightener,batching time,liquid rate and washing conditions on fabric whiteness were studied through single factor experiment and blank experiment.The optimal bleaching process was listed as follow: cold batch assistant L 12g/L,50%Na OH 25g/L,27.5%H2O2 40g/L,fluorescent brightener U 8g/L,batching temperature 25-30?,batching time 18 h,liquid rate 120-130%;washing conditions: 98?×20min.Under the optimum process conditions,the whiteness of fabric is similar to those by conventional high temperature pretreatment and whitening process,which meant cold pad batch pretreatment and whitening one step process is feasible for 20S/1 Interlock.Secondly,cold pad batch pretreatment and whitening process was conducted on three kinds of cotton knitted fabrics which are 20S/1 Jersey,30S/1 Pique,50S/1 Interlock.It was found that the whiteness of these three fabrics had a certain mismatch with the traditional process fabric,soaping after CPB and fabric setting process were studied to improve the whiteness of the fabric.According to the comparison and analysis of step above,we selected the best cold pad batch pretreatment and whitening whole process additive.The optimal whole process was listed as follow: cold batch assistant L 24g/L,50%Na OH 35g/L,other conditions are similar to 20S/1 Jersey,soaping agent Z 1g/L,fluorescent brightener T 0.5%,softening agent S 25g/L,penetrating agent W 1g/L,fluorescent brightener U 2g/L,setting temperature 130?,setting time 20S/1 Jersey(180s),30S/1 Pique and 50S/1 Interlock(130s).In order to simplify the whole process,six cold pad batch whole processes were carried out.According to the tests of brightness stability which conditions include storage,light and washing of whole process,screening the optimal process.Finally,the cold pad batch whole process was applied in workshop and then every index of the fabrics was tested.The results showed that,the three fabrics of cold pad batch pretreatment and whitening whole process got similar whiteness with the traditional process,and the fabrics have a good color fastness to light and washing fastness.The results showed that the optimized cold pad batch whole process of knitted fabrics with different structure,the whiteness of the fabrics is different.In conclusion,the research of whole pretreatment and whitening of cotton knitted fabrics by cold pad batch meets the demand green development and provide reference for practical conduction of workshop.