Preparation Of Multifunctional Waterborne Epoxy Resin And Its Application In Leather Tanning Process

Chrome tanning agent has been dominant in the leather tanning process because of its high tanning performance. However, the low absorption rate of chrome tanning agent leads to the waste of resources and serious pollution to the environment. The epoxy resin was used as tanning agent in the leather tanning process because of the high reactivity of epoxy group. Preparation process of waterborne epoxy resin is complicated,this study intends to synthesis a series of waterborne multifunctional epoxy resin based on the theory of free radical copolymerization, which take the epoxy monomer containing a double bond and vinyl monomers as the raw material. The waterborne multifunctional epoxy resin was applied in the tanning process of goat skin, the chromium amount and environmental pollution were reduced under the premise of guaranteed quality leather.Poly(methacrylic acid-allyl glycidyl ether) P(MAA-AGE) waterborne epoxy resin was prepared through free radical copolymerization, which take epoxy monomer cintaning double bond allyl glycidyl ether(AGE) and vinyl monomers as raw materials. The preparation process was optimized by the monomer conversion and rotational viscosity of P(MAA-AGE) as the indexes. A series of P(MAA-AGE) with different AGE amount were prepared. P(MAA-AGE) was characterized by fourier transformation infrared(FT-IR), hydrogen nuclear magnetic resonance(1H-NMR) and Gel Permeation Chromatography(GPC). The results showed that P(MAA-AGE) cintainning the carboxyl and epoxy groups and its molecular weight was about 1100 and PDI was 1.03. P(MAA-AGE) was applied in the tanning process of pickled goat skin, and the tanning process conditions were optimized by single factor experiment, the medium p H in two different tanning processes, reaction time and the P(MAA-AGE) amount were investigated, and the shrinkage temperature and the thickness increment ratio of the tanned leather as the index. Effects of the AGE amount on tanning performance and total chromium content loaded in wastewater was studied. Application results indicated that the shrinkage temperature of the leather tanned by P(MAA-AGE) combined with 3% chromate was 114.1℃, and thickness increment ratio reached 104% when AGE amount was 5%. Meanwhile, compared with the traditional chrome tanning method, the total chromium content loaded in wastewater reduced 77.43%, which indicated environmental pollution reduced effectively. Scanning electron microscopy(SEM) results of the tanned leather showed that the addition of P(MAA-AGE) could improve the dispersing performance of leather collagen fiber.Poly(acrylamide-glyoxal-acrylic acid-allyl glycidyl ether) P(AM-GL-AA-AGE) waterborne multifunctional epoxy resin was prepared by free radical copolymerization, the preparation process was optimized, the monomers, initiator amount, feeding methods of preparation were investigated, and the monomer conversion and rotational viscosity of P(AM-GL-AA-AGE) as the indexes. A series of P(AM-GL-AA-AGE) with different AGE amount were prepared. FT-IR 、1H-NMR and GPC results showed P(AM-GL-AA-AGE) containning the carboxyl, aldehyde and epoxy groups and its molecular weight was about 1450 and PDI was 1.06. P(AM-GL-AA-AGE) was applied in the tanning process of pickled goat skin, the thickness increment ratio and tensile strength of leather tanned by P(AM-GL-AA-AGE) with 3% chromate were improved significantly, and the total chromium content in wastewater reduced 77.57% compared to the traditional chrome tanning process. SEM indicated that the dispersion degree of leather collagen fiber tanned by P(AM-GL-AA-AGE) was higher than that of conventional tanned leather.P(MAA-AGE) waterborne epoxy resin was applied in the tanning process of bated goat skin, and the tanning process conditions was optimized by single factor experiment, the medium p H in two different tanning processes, reaction time and the P(MAA-AGE) amount were investigated, the shrinkage temperature and the thickness increment ratio of the tanned leather as the index. Effects of the AGE amount on tanning results were studied. Application results indicated that compared to the traditional chrome tanning process, the tanning performance of the leather tanned by P(MAA-AGE) combined with 3% chromate was approximately the same quality. CODCr reduced 70.02% significantly, total chromium content loaded in wasterwater reduced 69.95%, and the elution rate of chromate in each process after tanning process reduced. Achieved the tanning process without salt and pickling process.