Sythesis And Properties Of Sulfonated And Succinated Hydrogenated Castor Oil / Modified Nano-TiO₂ Composite Fatliquoring Agent

White leather is popular among customers. However white leather is easy to yellow in using process. Yellowing of leather is triggered by oxidization of unsaturated bond of leather chemicals and collagen under light and heat conditions. Key technologies to improve resistance to yellowing of leather are choosing high saturation leather chemicals and adding lightresistant agent. Fatliquoring agent is largely used in leather industry. Properties of fatliquoring agent have direct impacts on resistance to yellowing of leather. In this study, high saturation hydrogenated castor oil and rutile nano-Ti O2 with ultraviolet absorption function were employed to prepare yellowing-resistant composite fatliquoring agent, which would improve resistance to yellowing of leather.In this paper, sulfonated and succinated hydrogenated castor oil fatliquoring agents(SSF) were prepared by hydrogenated castor oil, maleic anhydride and sodium hydrogen sulfite. Emulsion stability, acid value and surface tension were selected as examining index to optimize the process. When ratio of maleic anhydride and hydrogenated castor oil was 1.05:1, p H value was 8.0, temperature of esterification was 95℃, esterification time was 3h, sulfonate reagent was sodium hydrogen sulfite, the ratio of sodium hydrogen sulfite and maleic anhydride was 1:1, alkali was ammonium hydroxide, an optimized process was acquired. SSF was used for fatliquoring process. The application results showed that tensile strength and elongation at break of crust leather fatliquored with SSF were similar with those fatliquored by commercial fatliquoring agent and sulfonated and succinated castor oil fatliquoring agent. The thickening rate of crust leather fatliquored by SSF was 22.6%, much higher than those fatliquored by commercial and sulfonated and succinated castor oil fatliquoring agent. Resistance to yellowing of crust leather was 3-4.Nanometer titania were modified by silane coupling agent and titanate coupling agent. The process was optimized via series of single-factor tests. The kinds of modifier, modifier dosage, p H value, modification temperature, reaction time and the ratio of absolute ethyl alcohol and water were optimized. Modified titanium were characterized by X-ray diffraction(XRD), fourier transform infrared spectroscopy(FT-IR), thermo gravimetric analysis(TGA), scanning electron microscope(SEM), dynamic laser scattering(DLS) and transmission electron microscope(TEM). FT-IR results showed that silane coupling agent and titanate coupling agent could successfully modify Ti O2. TEM and TGA indicated silane coupling agent and titanate coupling agent coated on Ti O2. The order of coating rate was hexadecyltrimethoxysilane > dodecyltrimethoxysilane > γ-(2, 3-epoxypropoxy)propytrimethoxysilane > 3-Aminpropyltriethoxysilane for silane coupling agent, and titanate coupling agent NDZ130 > titanate coupling agent NDZ201 > titanate coupling agent TM-P for titanate coupling agent. The XRD results showed that crystal structure of modified Ti O2 was not changed. DLS and SEM results showed that particle size of modified Ti O2 were decreased, compared with unmodified Ti O2.Titanate coupling agent TM-P modified Ti O2(TM-P-Ti O2) and 3-Aminpropyltriethoxysilane modified Ti O2(KH550-Ti O2)(0, 1%, 2%, 3%, or 4%, according to solid content) were added into sulfonated and succinated hydrogenated castor oil fatliquoring agent via in-situ method to prepare sulfonated and succinated hydrogenated castor oil/TM-P-Ti O2 composite fatliquoring agent(SSF/TM-P-Ti O2) and sulfonated and succinated hydrogenated castor oil /KH550-Ti O2 composite fatliquoring agent(SSF/KH550-Ti O2). SSF/KH550-Ti O2 and SSF/TM-P-Ti O2 were used for fatliquoring process. SSF/KH550-Ti O2 and SSF/TM-P-Ti O2 were characterized by emulsion stability, UV absorbance, DLS and TEM. Fatliquored crust leathers were characterized by flexibility, thickening rate, mechanical properties and resistance to yellowing. Microstructure of crust leather was characterized by SEM. Emulsion stability tests showed a satisfied stability of composite fatliquoring agent. DLS tests showed that average particle size of composite fatliquoring agent reduced with the introduction of KH550-Ti O2 or TM-P-Ti O2, compared with that of SSF. UV absorbance detection showed that introduction of KH550-Ti O2 or TM-P-Ti O2 could increase the UV absorbance of composite fatliquoring agent, and the UV absorbance of composite fatliquoring agent increased with the dosage of modified Ti O2 increasing. TEM results showed that KH550-Ti O2 or TM-P-Ti O2 could evenly disperse in composite fatliquoring agent and particle size of modified Ti O2 was uniform. SSF/TM-P-Ti O2 application results showed that introduction of TM-P-Ti O2 could increase the tear strength, elongation at break, thickening rate and softness of leather, these properties increased with the dosage of TM-P-Ti O2 increaseing. Resistance to yellowing of crust leather also increased with the dosage of TM-P-Ti O2 increaseing, and the best resistance to yellowing was 4-5. The introduction of KH550-Ti O2 could improve the tensile breaking strength and tear strength of leather, thickening rate and softness. Resistance to yellowing of crust leather increased with the dosage of KH550-Ti O2 increaseing. When the dosage of KH550-Ti O2 was 4%, resistance to yellowing was 5. SEM showed that the introduction of KH550-Ti O2 could improve collagen fiber loose degree. KH550-Ti O2 could well disperse in leather, and more KH550-Ti O2 were observed near the grain.