Environmentally Friendly Catalyst Sodium Nitrate Of Btca Durable Press Finishing System Development And Research

Polycarboxylic acids durable press finishing of cotton fabric meet the request of ecology , the catalysts containing phosphorus used with the process, however, bring pollution to environment. It is not only against the standard of clean "green" processing but also against the original intention of using polycarboxylic acids for fabric DP finishing. Based on comprehending the characteristic and mechanism of present phosphorus containing catalysts, sodium nitrate (SN) is developed as a new non-phosphorus catalyst for cross-linking of cotton fabric with 1,2,3,4- Butanetetracarboxylic acid (BTCA), and then studied its system variables, finishing effect and mechanism . Experimental results reveal that SN has the capability to catalyze esterification of BTCA with cotton fabric. Consequently a series of work has been done to further discussion. First, wrinkle recovery angle (WRA), whiteness (Wh) and breaking strength retention (BSR) of fabric finished with BTCA/SN system as evaluation indexes are measured to analyze the influence of such factors as concentration of SN, curing time, curing temperature and pH of working bath ; Secondly synthetical influence of the former three factors is investigate through L9(3)4 orthogonal experiment, in addition, an optimum formulation is achieved after verifying the obvious factors with F test. The results of comparing SN with phosphorous catalysts are as follows: WRA of treated fabric with BTCA/SN is superior to that with other phosphorous catalysts except sodium hypophosphite (SHP); as to BS, SN system is lower than SHP and disodium phosphate system but higher than other phosphorous catalysts; however, fabric whiteness of sodium nitrate system is not as good as that of all phosphorous catalysts. In a word, sodium nitrate is a promising environment-friendly catalyst for polycarboxylic acid finishing potentially instead of SHP.Chemical and instrumental methods are used to explore thecatalyzing mechanism of SN. The results of FTIR, thermoanalyse and hydroximic acid test indicate that SN can accelerate the formation of cyclic anhydride of BTCA, Hence the catalyzing mechanism of SN is deduced that nitrate radical having conjugative n bonds with 4 negative centers of 6 electrons is a nucleophilic agent, and attack carbonium of carbonyl group in carboxylic acid to form organic nitrate intermediates to speed up dehydration of BTCA. Experiment result of brown ring, diphenylamine and Kjeldahl method confirm that SN accelerate the esterification of BTCA with cellulose, and without consumption and character change itself in the whole reaction.Furthermore, the pseudo-first-order reaction mode is established with respect to BTCA/SN reaction system. Kinetic data demonstrate the decrease of activation energy of BTCA esterifying cellulose can attribute to SN catalysis.Finally, various esterification products including monoester, diester and triester of BTCA/SN/fabric system were analyzed and calculated to erect other reaction mode.