Preparation Of Amino-Terminated Hyperbranched Ployers And Its Application On Leather

The preparation of amino-terminated hyperbranched polymers （NH₂-HBP） was based on previous single-factor experiment results. The optimal preparation process parameters of NH₂-HBP were studied by orthogonal experiment. The NH₂-HBP was applied in dyeing, formaldehyde-removal and retanning process of sheep skin garment leather to study its optimal application parameters in leather. The main research contents and results are as follows.The parameters optimization of NH₂-HBP preparation process was carried out through orthogonal experiment, in which N, N-methylene bisacrylamide and diethylene triamine were used as raw materials, the yield and amino content were as indexes. The optimum conditions were the mol ratio of N, N’-methylene bisacrylamide and diethylene triamine was 1:1.2, the temperature was 80℃ and reaction time was 24h. The significance test indicated that the reaction temperature had a significant effect on the yield and the content of amino groups. The infrared spectrum showed that NH₂-HBP molecules were successfully synthesized according to expected route. The determining result of NH₂-HBP by using gel permeation chromatography showed that the number average molecular weight was up to 2088, and the weight average molecular weight was up to 2472. The synthesis of NH₂-HBP was reproducible and stable, the average yield of NH₂-HBP was 90.23%, the average amino content of NH₂-HBP was 2.72mmol/g, as well as the production rate and variation coefficient of amino content were low. The physical properties of NH₂-HBP were tested. The NH₂-HBP had irritating ammonia odor, the solid content was about 31% and the water solubility was good.The optimal NH₂-HBP was applied in the dyeing process of sheep skin garment leather. Through the contrast test for the adding sequence of NH₂-HBP before and after formic acid, the effect of NH₂-HBP on fixation was studied. The results showed that NH₂-HBP was added after formic acid was better. Then the amount of NH₂-HBP was optimized by single-factor experiment. The results showed that when the dosage of NH₂-HBP was 0.6% and it was added after the fixation by using formic acid, the dye uptake rate increased 5.41%, the dry and wet rubbing fastness of leather increased by 0.5 level and 1 level. Meanwhile, under the conditions of the dyeing process, the thickening rate and the physical and mechanical properties of leather were improved.The NH₂-HBP was applied in the formaldehyde-removal process of sheep skin garment leather. The amount and application time were optimized via single-factor experiment. The results showed that when the amount of NH₂-HBP was 4% and the application time was 20min, the content of free formaldehyde in leather could be reduced from 649.23mg/kg to 111.47mg/kg, decreased by 82.83%. Meanwhile, the influence of NH₂-HBP on the physical and mechanical properties was also tested. The test showed that the addition of NH₂-HBP could improve the thickening rate and physical and mechanical properties of leather.The optimal NH₂-HBP was applied in the retanning process of sheep skin garment leather to study its retanning properties. The results showed that when 6% NH₂-HBP was added before fatliquoring, the physical and mechanical properties of leather was improved. The average Ts increased 4.4℃, the average tensile strength increased from 11.76N/mm2 to 15.94N/mm2, increased by 35.54%, the average tear strength increased from 22.47N/mm to 33.73N/mm, increased by 47.31%. Meanwhile, the effect of NH₂-HBP on the dyeing properties of leather was also detected. The results showed NH₂-HBP could improve the dyeing properties of leather, and the dye-uptake increased by 5.06%, the dyeing waste liquid was transparent and light in color, the grain color of leather became deeper.