Preparation Of Hydroxypropyl Starch And Its Application In The Acid Dye Printing

Traditional acid dye printing paste mainly used guar and its derivatives, in recentyears, affected by supply and demand,guar gum prices climbed dramatically,researchers began to seek new pastes to substitute guar gum. Hydroxypropyl starch isa non-ionic starch derivatives, environmental, cheap price, with good acid and alkaliresistance, it can be used for acid dye printing.This paper prepared hydroxypropyl starch(HPS) soluble in cold water by solventmethod, the effects of reaction temperature, reaction time, ratio of ethyl alcohol andwater, ratio of liquid and solid etc were studied. The result showed that under thesame conditions,the higher the temperature, the higher the reaction efficiency, thelonger the reaction time, the higher the MS. In a certain extent, the higher the bathratio, the higher the MS, with the catalyst dosage increasing, the MS increased firstand then decreased.The MS increased and the reaction efficiency decreased as thedosage of etherification agent increased, the reaction efficiency can reach70%bysolvent method prepared HPS. The higher the MS, the higher the transparency ofsolution of HPS. The optimum reaction conditions: reaction temperature was75℃,reaction time was10h, bath ratio was1.5:1, catalyst dosage was4%, water content of15%, can prepared HPS with high molar substitution was0.50. But the HPS pasteexistence the defects of low pasting rate and the hand feeling not idea.This paper synthesised hydroxypropyl carboxymethyl starch(HPCMS) on thebasis of the preparation HPS, to make up for the deficiencies of a single modified in the application. Characterized and analysised different products by infraredspectroscopy, polarized light microscopy and thermal gravimetric. Thecarboxymethylation study showed that the higher the temperature, the lower thereaction time, the viscosity solution of HPCMS decreased, the reaction efficiencydecreased. The viscosity and transparency of solution of HPCMS increased as thepurity of HPCMS increased. The high degree of substitution of HPS and HPCMS hadgood acid and alkali resistance, performance of resistant calcium and salt. Originalpaste had good compatibility with dye,ammonium had little effect on the originalpaste viscosity, the viscosity decreased as the amount of urea increased.Carboxymethylation reaction obviously improved HPS rheological behavior, waterretention, permeability, edge sharpness, paste removal rate and the transparency ofaqueous. HPS and HPCMS paste color yield were higher than the guar gum paste.Complex modified HPCMS had high pasting rates than single-modified HPS, whenDS between0.2~0.3and MS between0.34~0.43, HPCMS had a high pasting rate. Itcan replace guar gum paste used for acid dye printing, and had a excellentcomprehensive index.