Study On Synthesis Of Hyperbranched Polymer With Terminal Carboxyl And Its Effect Of Chrome-Tanning Assistant

As the chrome–tanning method has many good properties, it is also the main tanning method during the recent times. But its pollution become more and more serious because it has given terrible effect to the existence of animals & plants and the health of human. Now, on the one hand, the pollution can not get the thorough solving, on the other hand, our chrome resource is limited. So the main problem of the leather industry in the future is to study the chrome–tanning assistant agent with high absorbability to reduce the chrome pollution.In recent years, hyperbranched polymer takes on new structure, special properties and potential applying foreground, so they are given recognition and good graces by lots of researchers and it can be regarded to be the important developing direction of polymers during the 21st century. According to the special properties of hyperbranched polymer and its detailed state in leather making process, the applying foreground of hyperbranched polymer in leather industry was systematically analyzed in this paper. The hyperbranched polymer with terminal carboxyl has large numbers of carboxyl groups which can complex with chrome(Ⅲ), so it can be used as chrome tanning assistant agent with high absorption. Compare to ordinary chrome tanning assistant agent with high absorption, the hyperbranched polymer has more complexing groups, so its effect of absorbing and fixing chrome is better. Meantime, it can spare chromium, reduce chrome pollution in float and protect environment so that it can get the effect of killing two birds with one stone.This paper introduces that two kinds of hyperbranched polymer (HP–Ⅰand HP–Ⅱ) by one–step method; their stability of acid–resistance, alkali–resistance, salt–resistance, chrome powder resistance and extract resistance and their structure are showed by infrared red spectrum, ultraviolet spectrum and gelatin penetration chromatogram. Trough applying experiment the best applying conditions of HP–Ⅰand HP–Ⅱwas optimized. Moreover, the influence of HP–Ⅰand HP–Ⅱon chrome powder absorption and mechanism properties.The hyperbranched polymer with terminal amino group was synthesized with 3, 5-diaminobenzoic acid and then was modified with aldehyde acid to get HP–Ⅰ.The optimum synthesized conditions of HP–Ⅰare: monomer 0.2g/mL, the reaction time 6h, temperature 160℃. Furthermore, the middle product was synthesized with succinic anhydride and diethanolamine and then was modified with maleic anhydride to get HP–Ⅱ.The structure and relative molecular weight of monomer, hyperbranched polymer with terminal amido, HP–Ⅰand HP–Ⅱwere showed by IR, UV and GPC. The results showed that the reaction was carried out according to designed route.The test about stability showed that when pH is over 1.5 the solution of HP–Ⅰand HP–Ⅱare stable; the stability of salt–resistance, chrome powder resistance and extract resistance is good. So these properties of HP–Ⅰand HP–Ⅱset a basis for their application.The optimum technics conditions of HP–Ⅰobtained as follows: it is used before the chrome; the perfect dosage is 2%; the amount of chrome–tanning agents which used together is 5%; the pH of the termination of tanning is 4.0~4.2.The application results of HP–Ⅰindicate that the assistant agent has good ability to promote the absorbability of chrome and dyes, with good fill function and physical properties. We can save chrome by 28.6%(based on 7% of chrome–tanning agents) by using this agent; The concentration of Cr2O3 of waste water from the sample which used chrome–tanning assistant agent is 0.29g/L, that of the sample which not used is 0.48g/L, reducing by 39.6%, the rate of chrome absorbability is high to 95.4%; the rate of dyeing is high to 94.82%, increasing by 2%. Furthermore, the application results of HP–Ⅱindicate that the assistant agent has good ability to promote the absorbability of chrome and dyes, with good fill function and physical properties. We can save chrome by 28.6%(based on 7% of chrome–tanning agents) by using this agent; The concentration of Cr2O3 of waste water from the sample which used chrome–tanning assistant agent is 0.27g/L, that of the sample which not used is 0.57g/L, reducing by 52.6%, the rate of chrome absorbability is high to 96.8%; the rate of dyeing is high to 95.58%. Comparing with the general method, the application results of HP–Ⅱwas as follows: The concentration of Cr2O3 of waste water reduced from 1.21g/L to 0.27g/L, reducing by 77.7%, the rate of chrome absorbability increased from 78.1% to 96.8%, increasing by 23.9%.The theory of hyperbranched polymer was firstly introduced to leather science field and analysed application foreground in leather industry by the numbers. According to synthesizing theory of hyperbranched polymer, two kinds of hyperbranched polymer with terminal carboxyl group were synthesized firstly and tokened by IR, UV and GPC. Lastly, hyperbranched polymer assistants were used firstly in chrome tanning and its application condition & physics mechanism performance were studied.