Synthesis Of Composite-modified Starch And Its Application In Reactive Dye Printing

Printing with reactive dyes is the most widely used printing process for cellulosefabric.At home and abroad,sodium alginate has been mainly used as the reactive dyeprinting paste since the inception of reactive dyes.However,with the development ofprinting technology and the increasing product quality demands of consumers,sodiumalginate is far from enough to meet the requirements of high-quality printing.Inaddition,people have found the food value of sodium alginate in recent years and ithas gradually become food which has led to the rising prices.And that has increasedthe cost of printing.Therefore,the domestic and foreign researchers have begun tostudy and develop new printing paste for reactive dyes.Starch is abundant in source and cheap in price.Different from sodiumalginate,starch molecules contain a large mumber of primary hydroxyl groups whichcan react with reactive dyes and influence the shade and color yield.That is whystarch can not be directly used as reactive dye printing paste.Therefore,starch has tobe modified.On the one hand,the highly active primary hydroxyl group wascarboxymethylated and the more hydrophilic sulfoethyl group was also intrduced intothe starch molecule,which made anionic starch.That can increase the exclusion ofstarch from reactive dyes.On the other hand,the structural viscosity was increasedthrough the chemical cross-linking effect.Then composite-modified starch wasobtained.Composite modification can make up for the deficiency of singlemodification.Moreover,sodium alginate and carboxymethyl cellulose were chosed tostudy the mixture of the composite-modified starch and these two thickeners.Theapplication of the mixed thickeners was also studied.The thickeners used in thisresearch are easily biodegradable,innoxious,harmless and environment-friendly,whichis consistent with the current social trend of environmental protection.In the preparation part,effects of alkalization temperature,alkalization time,n(starch)/n (NaOH),etherification temperature and etherification time on thecarboxymethylation;effects of types of sulfoethyl reagent,the dosage of sulfoethylreagent,alkalization temperature and alkalization time on the sulfoethylation;effects ofcrosslinking temperature,crosslinking time,the dosage of crosslinking agent and pH on the crosslinking reaction were discussed.The results showed that the optiumconditions of carboxymethylation were as follows: alkalization temperature40℃,alkalization time60min, n (starch)/n (NaOH)1︰1.9, etherification temperature50℃and etherification time3h.Sodium chloroethanesulfonate was chosed as sulfoethylreagent.However,it was found that the addition of sulfoethyl reagent largelyinfluenced the carboxymethylation.And degree of sulfoethyl substituent determinedby elemental analysis was very low while the performance of the product waspoor.The optium process conditions of crosslinking reaction were as follows:thedosage of crosslinking agent was60μL,crosslinking temperature was50℃,crosslinking time was1h and crosslinking pH was11.In the application part,the mixture of the composite-modified starch and CMC orSA,the printing properties of the composite-modified starch and the mixed thicknerswere mainly discussed.The results showed that the actual printing effect of the singlecomposite-modified starch was similar to that of SA while K/S and the hand propertywas unsatisfactory.The mixture of composite-modified starch and SA(8︰2) wasexcellent in the reactive dye printing and the actual printing effect was equal to that ofSA.Moreover,it may surpass SA in some aspects.