| Fatliquoring agent is one of the most indispensable and most widely used leather chemicals in leather processing.It can give the leather fullness and softness.However,during leather use,transportation and storage,the oil components in the fatliquoring agent easily migrate to the surface,which increases the flammability of the leather and reduces the safety of leather use,thereby causing potential dangers to people's lives and property safety.Therefore,how to improve the flame-retardant and smoke-suppressing properties of the leather fatliquoring agent is an urgent problem to be solved.In this research,metal organic frameworks(MOFs)and layered double hydroxides were used as additive flame retardants,and were introduced into modified castor oil to prepare composite fatliquoring agent.The purpose was to explore the flame-retardant and smoke-suppressive properties of the crust leather after fatliquoring.The main research contents were as follows:(1)Using cobalt nitrate,zirconium chloride and ferric chloride as metal salts and terephthalic acid as organic ligands,cobalt-based metal organic frameworks(Co-BDC),zirconium-based metal organic frameworks(UiO-66)and iron-based metal organic frameworks(MIL-101)were prepared.The effects of the above three types of MOFs on the flame-retardant and smoke-suppressing of fatliquoring crust leather were investigated.X-ray diffraction(XRD)and thermogravimetric(TG)results showed that three MOFs with high crystallinity and good thermal stability were successfully prepared.The above three MOFs were introduced into modified castor oil to fabricate the composite fatliquoring agent and then was applied to the fatliquoring process of crust leather.The results showed that the addition of MOFs can inhibit the heat release behavior of fatliquoring crust leather,in which.the heat release behavior of the composite fatliquoring agent of the modified castor oil/UiO-66 was significantly lower than that of the modified castor oil fatliquoring.(2)Using zirconium chloride and terephthalic acid as raw materials,the type and amount of doped metal elements were optimized,and the optimal process of doping UiO-66 was determined.XRD and TG results showed that when the doping element of Cu2+ and the molar ratio of Zr4+to Cu2+was 9:1,copper-doped zirconium-based metal organic frameworks(Cu-UiO-66)with uniform size,regular morphology and better thermal stability was obtained.Cu-UiO-66 was introduced into castor oil in situ to prepare the composite fatliquoring agent and then was applied to the crust fatliquoring process.The results indicated that:compared with the modified castor oil fatliquoring crust leather,when the addition amount of Cu-UiO-66 was 6%,after flame time of the fatliquoring crust leather process of the composite fatliquor agent was reduced by 51.6%,the damage length was reduced by 40.7%,the mass loss rate was reduced by 46.3%,and the peak heat release rate(pHRR)was reduced by 54.2%,the total heat release(THR)was reduced by 37.7%,the smoke production rate(SPR)lowered 49.6%,and the total smoke production(TSP)decreased to 65.8%.The flame retardant and smoke suppression mechanism of the crust leather was further explored.It was found that Cu-UiO-66 can penetrate and wrap the crust leather collagen fibers,which can delay the smoke release and form a dense carbon layer to further improve the flame retardancy and smoke suppression of the crust leather.(3)Using acetone as the modifier to modify the surface of layered double hydroxides to obtain an acetone-treated layered double hydroxides(A-LDH)with lipophilicity and hydrophobicity,good dispersibility and resistance to agglomeration.Cu-UiO-66 and A-LDH were introduced into the modified castor oil to prepare the composite fatliquor agent,which was then applied to the crust fatliquoring process.The results displayed that:fatliquoring with the modified castor oil fatliquoring compared with the modified castor oil fatliquoring crust leather,when the amount of A-LDH was 8%,after flame time of the composite fatliquor agent was reduced by 75.3%,the damage length decreased to 79.1%,the mass loss rate lowered 79.2%,and the pHRR was reduced by 60.8%.THR was reduced by 66.8%,SPR was reduced by 62.0%,and TSP was reduced by 67.8%.The mechanism of the flame retardant and smoke suppression properties of the crust leather was further explored,and it was found that Cu-UiO-66 and A-LDH can dilute oxygen,absorb heat and flue gas,catalyze carbonization and oxidation during the pyrolysis process,thereby achieving flame retardancy and smoke suppression. |
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