Study On Modified Starch And Its Printing Properties

Reactive dyes are characterized by full spectrum of color, bright color and other advantages, which are suited for dyeing and printing fields. Sodium alginate has been widely used as reactive dyes printing thickener, because of its good pasting ability, water-retention property, PVID value, and the high printed fabric has good fabric softness, shade and other excellent properties. In recent years, sodium alginate also has been widely used in other fields, such as medicine, food, which drive its price up, and increased the printing and dyeing enterprise production cost, so developed a new thickener is necessary. Two kinds of new reactive dye printing thickeners are studied in this paper, maize starch is cheap and have abound resources, so it is taken as raw materials to graft acrylic acid and chloroacetic acid, modified starches are synthesized. The properities of modified starch have reached the requirements of reactive dye printing thickener. The modified starches would be good sodium alginate’s substitute for enterprises, and it have good market prospects. The main results are as follows.(1) Acrylic acid grafted starch. Acrylic acid is taken as monomer to graft starch which is need to acid hydrolysis, in order to improve the starch grafting rate. The orthogonal experiment method was used to obtain the optimized acid hydrolysis process:acid hydrolysis temperature50℃hydrolysis time1.5h,1mol/L acid10mL. The optimum processes of modified starch are as follows:n(AA):n(AGU)=2:1, n((NH4)2S2O8):n(NaHSO3)=2:1, acrylic acid monomer pH=6, the reaction temperature and time are50℃and3h. The productivity of modified starch yield was48.72%, the grafting rate and grafting efficiency were6.94%and54.45%, the water-retention property of modified starch is3.2mm, and the PVID value is0.37. The Fourier transform infrared spectroscopy is used to characterize modified starch groups; the SEM is used to observe the unmodified and modified starches surface.(2) Carboxymethyl starch. Carboxymethyl starch is synthesized by chloroacetic acid and acidolysis starch, The optimum acid hydrolysis process are as follows:acid hydrolysis temperature50℃, hydrolysis time2h, hydrochloric acid10mL. The substitution degree (DS) of carboxymethyl starch (CMS) and its paste properties are calculated and tested. The optimum process of carboxymethyl starch are as follows: n(NaOH):n(AGU)=3:1, n(MCA):n(AGU)=1.5:1, basification temperature is35℃, the etherification temperature and time are60℃and2h. The DS of carboxymethyl starch is0.45, the water-retention property is2mm, and the PVID value is0.513. The Fourier transform infrared spectroscopy is used to characterize carboxymethyl starch groups; the SEM is used to observe the unmodified and modified starch surface.(3) The paste properties and printing performance. The printing thickeners of reactive dye are used to printing cotton fabric, the thickeners contain acrylic modified starch, carboxymethyl starch, maize starch and sodium alginate. The different types of printing thickeners properties and printed fabrics performance are tested. The results showed that, two kinds of modified starches are similar as sodium alginate in the thickener properties, and the printed fabrics performance which contains fixation rate, stiffness, K/S value are the same as sodium alginate’s. At the same time, the compatibility between modified starches and the chemicals which are used in printing are tested, the results show two kinds of modified starches are slightly lower than sodium alginate on the stability, but the modified starches are still reached the printing thickener requirements.In summary, the thickener properties and printed fabrics performance of modified starches are similar as sodium alginate, the requirements of reactive dye printing are satisfied, the modified starches could be used as sodium alginate’s alternatives.