The Preparation And Application Research Of Modified Polysaccharides Reactive Printing Paste

Sodium alginate has been used as the main printing paste since reactive dyes appeared.With the development of the printing tecnology, a variety of weakness comes out when sodiumalginate use as the round and flat nets printing paste, and the price of sodium alginate never stopincreasing. So people scrambling to start the research of its alternatives. At present, themainstream of research direction is modified polysaccharides paste, including CMC, CMG andCMS, but the difference between the performance of them are unknown.In order to compare the application performance of CMC, CMG and CMS, the three highsubstitution degree of modified paste were prepared, the reaction conditions were optimizedthrough the orthogonal experiment, the factor’s influence to the product were discussed, and thebest preparation process were obtained. In addition, the structure of the product was analyzed byFTIR and XRD.According to the character that cellulose goes swelling when contract strong alkali, cottonfiber will be treated after a strong alkali treatment before the experiment start, so that the productwith higher degree was obtained. In order to find the reason, the cotton cellulose which treatedwith and without strong alkali were analyzed by SEM and XRD, the results showed that:cellulose goes swelling after the strong alkali treatment, the cryatal changed, part of celluloseⅠturned into cellulose Ⅱ, meanwhile its crystallinity turned lower, the hydrogen bondingbetween molecules were separated, too much reactive groups exposed, the reaction activity wereinproved, so that the higher substitution degree were obtained. At the same time, the higherconcentration of the alkali, the lower crystallinity of the cellulose. When the concentrationreached500～600g/L, the dropment of crystallinity turned unconspicuous, the reaction activityof the cellulose reached its maximum, thus the substitution degree rise no longer.The application performance of CMC, CMG and CMS were tested, including basicproperties and printing properties, and compared with sodium alginate. The results showed that:CMC, CMG and CMS all belong to fake plastic fluid which has low PVI value, so that they aremore suitble for the round、flat nets printing than sodium alginate. The viscosity of CMC and CMG are close, with fine outline of pattern. The viscosity of CMS is lower, but its morehydrophilic, easy removing, high color quantity and good penetrability. The CMS which made ofpotato starch has the best performance in CMS series.The contrast of three paste showed that: CMC and CMG have the similar performance,CMS series paste are different to the two. For purpose of composite the single excellent featuresof each paste, CMC and CMS-potato which both have fine performance but different to eachother were chosen to mixed, and the application performance were tested. The results showedthat: if mixed paste contains more CMC, the viscosity will be large, the outline of pattern will bemore clear, so it is suitble for the fine pattern printing. If the proportion of CMS-patato is larger,the mixed paste will be more hydrophilic, with good penetrability, so that it is more suitble forthe large pattern printing.