With the enhancement of environmental protection consciousness,concerns have been raised about non-toxic and biodegradable leather retanning agents.According to the European standard 2002/231/EC,the free formaldehyde ...With the enhancement of environmental protection consciousness,concerns have been raised about non-toxic and biodegradable leather retanning agents.According to the European standard 2002/231/EC,the free formaldehyde content of leather products should be less than 150 mg/kg.As one of the retanning agents in the market,the content of free formaldehyde in the Multifunctional retanning agent(MTA)is 372.22 mg/kg and higher than the limit value.In this work,glutaraldehyde as an alternative of formaldehyde was used to modify acrylic polymer and an amphoteric acrylic retanning agent was prepared.Then it was used in retanning process,and its retanning and assistant-dyeing properties were investigated.The results showed that the free formaldehyde content of amphoteric acrylic retanning agent modified with glutaraldehyde was only 4.17mg/kg.Meanwhile,the presence of amino groups in the amphoteric acrylic retanning agent improved the dyeing properties of leather by electrostatic attraction.Compared with the leather treated with anionic acrylic retanning agent,the residual dye concentration of the dyeing effluent of the retanned leather with amphoteric acrylic retanning agent decreased from 17.4mg/L to 10.0mg/L,and the dyed leather had better resistances to friction and water-washing.In addition,the BOD 5/COD value of the wastewater after Mannich base polymer retanning was only 0.32,indicating that the retanning agent was biodegradable.Moreover,the leather retanned with amphoteric acrylic retanning agent had good thermal stability,fullness and physical and mechanical properties.展开更多
A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible ...A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible with this emerging tannage needs to be investigated systematically.This paper aims to explore the interaction between the bimetal complex tanned wet white and retanning agents.The isoelectric point(pI)of wet white was 7.2,which was nearly the same as wet blue.The electropositivity of wet white was even higher than that of wet blue during post-tanning processes,resulting in higher uptake rate of retanning agents.The distribution of various retanning agents in wet white was analyzed by pI measurement of layered leather and fluorescent tracing technique.The retanning agents were unevenly distributed throughout the cross-section,which might be an important restriction factor in obtaining satisfactory organoleptic properties of the crust leather.This fact is mainly due to the strong electrostatic interaction between anionic retanning agents and wet white.Applying a high dosage of multiple retanning agents in a proper sequence of addition benefited the full penetration of retanning agents in leather matrix and thus improved the organoleptic properties of crust leather.This work provides guidance for optimizing retanning process of the wet white leather.展开更多
基金The financial support of this study was from the Key Program of National Natural Science Foundation of China(No.21838007)National Natural Science Foundation of China(No.21706151).
文摘With the enhancement of environmental protection consciousness,concerns have been raised about non-toxic and biodegradable leather retanning agents.According to the European standard 2002/231/EC,the free formaldehyde content of leather products should be less than 150 mg/kg.As one of the retanning agents in the market,the content of free formaldehyde in the Multifunctional retanning agent(MTA)is 372.22 mg/kg and higher than the limit value.In this work,glutaraldehyde as an alternative of formaldehyde was used to modify acrylic polymer and an amphoteric acrylic retanning agent was prepared.Then it was used in retanning process,and its retanning and assistant-dyeing properties were investigated.The results showed that the free formaldehyde content of amphoteric acrylic retanning agent modified with glutaraldehyde was only 4.17mg/kg.Meanwhile,the presence of amino groups in the amphoteric acrylic retanning agent improved the dyeing properties of leather by electrostatic attraction.Compared with the leather treated with anionic acrylic retanning agent,the residual dye concentration of the dyeing effluent of the retanned leather with amphoteric acrylic retanning agent decreased from 17.4mg/L to 10.0mg/L,and the dyed leather had better resistances to friction and water-washing.In addition,the BOD 5/COD value of the wastewater after Mannich base polymer retanning was only 0.32,indicating that the retanning agent was biodegradable.Moreover,the leather retanned with amphoteric acrylic retanning agent had good thermal stability,fullness and physical and mechanical properties.
基金financially supported by the National Natural Science Foundation of China(21506129).
文摘A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible with this emerging tannage needs to be investigated systematically.This paper aims to explore the interaction between the bimetal complex tanned wet white and retanning agents.The isoelectric point(pI)of wet white was 7.2,which was nearly the same as wet blue.The electropositivity of wet white was even higher than that of wet blue during post-tanning processes,resulting in higher uptake rate of retanning agents.The distribution of various retanning agents in wet white was analyzed by pI measurement of layered leather and fluorescent tracing technique.The retanning agents were unevenly distributed throughout the cross-section,which might be an important restriction factor in obtaining satisfactory organoleptic properties of the crust leather.This fact is mainly due to the strong electrostatic interaction between anionic retanning agents and wet white.Applying a high dosage of multiple retanning agents in a proper sequence of addition benefited the full penetration of retanning agents in leather matrix and thus improved the organoleptic properties of crust leather.This work provides guidance for optimizing retanning process of the wet white leather.
