Preparation Of A Novel Acid Donor And Study Of It’s Influences To The Dyeing Properties

pH Value is a crucial process parameter to affect the rate and the ratio of dye up-taking. In order to improve the percentage of dye up-taking, weak acid dye usually dyes in the weak acidity condition. In this situation, dyestuff initially has higher up-taking ratio. The homogeneity of dye leveling is suffered and uneven dying is resulted. For the sake of excellent dye leveling property, acid donor may be added to the dyeing bath, so as to lower initial dye up-taking ratio and to ensure dyestuff up-takes evenly. During the dyeing process, pH value moves towards acid side in the dyeing bath. In the end of dyeing process, dyeing bath has relatively low pH value. Eventually a high dye up-taking ratio or exhaustion of dyestuff can be found so that the utilization rate of dyestuff is high.This thesis is to study of the acid releasing properties of several polyacid esters in the beginning. It shows that polyacid ester compounds are not suitable as acid donors. Since polyacid ester imports quite high hydrolysis stability, it cannot be used satisfactorily to meet the requirements of initial pH value of 7-8 and final pH value of 3-5 in the polyamide dyeing process. The study of the acid releasing properties and hydrolysis stability of polyalcohol esters are conducted. It is found that 1,4-butanediol diformate and 1,4-butanediol monoformate are suitable to be used as acid donors for acid dyestuff dyeing. The optimization experiment indicated that the good acid releasing property can be obtained in the mixing ratio of the two compounds as 4:6.By choosing formic acid and 1,4-butanediol as raw materials, the influences of type and amount of catalyst, type and amount of water-carrying agent, molar ratio of raw materials, to the yield of esterification reaction, water content, pH value of lg/L tap water, di-ester and mono ester ratio and others, are studied. Finally the optimized condition of preparation of acid donor is obtained. When the amount of acid cationic resin is as a catalyst 0.2% of formic acid by molar ratio; the amount of isopropyl ether water-carrying agent is 20% of formic acid by molar ratio; the ratio of formic acid and butanediol is equal to 1.35:1, the satisfied acid donor with a mix ratio of di- and mono esters of 4:6 can be obtained. By column separation experiment, 1,4-butanediol monoformate and 1,4-butanediol diformate can be found. Characterizations by FT-IR, NMR and mass spectroscopy confirmed their structure. The compositions of products of mixed ester are determined by HPLC, which are consisted with expectation.Weak acid dyestuff Telon and neutral dyestuff Lanaset are used in presence of acid donor or acetic acid. Polyamide 6 and 66 dyeing properties are studied respectively. It shows that no matter whether light or dark color dyeing process, dye leveling property is better by adding acid donor in polyamide fabric dyeing from 50℃～98℃with lower K/S values at each temperature range, than that by adding acetic acid at the same condition. With increases of temperature and preservation time, adding acid donor and acetic acid are eventually towards to get the same color depth to both polyamides. For the dark color dyeing process, in the end of dyeing the polyamide fabric has slightly higher color depth by adding acid donor than acetic acid.Weak acid dyestuff Telon and neutral dyestuff Lanaset are used, in presence of acid donor or acetic acid respectively. Water durable fastness, abrasion fastness, and perspiration fastness of dyed polyamide 6 and 66 fabrics are studied. The results indicate that this new acid donor has no adverse effect on wet fastness and other color fastness specifications. This excellent acid donor may put up with good commercial value.