Research Of Silk Fibroin Modified As Leather Finishing Agents

At present, leather-finishing agents mostly are: polypropylene resin, polyurethane, nitrocellulose and cheese native protein finishing materials. The polypropylene resin covers 70% of the market. These synthesize finishing materials have excellent mechanical properties and appearance performance, but their air and water permeability property are quite bad. So it is necessary to modify them. Because the silk fibroin (SF) is a kind of native protein, and has nicer compatibilities to collagens, it can modify synthesize finishing materials by method of cross blending. When the fibroin forms films, it's handle and luster will become nicer. So in this research the silk fibroin will be blended with synthesize finishing materials to develop a new kind of leather finishing agent. In this paper, the silk fibroin (SF) was dissolved through two ways. And the film prepared by SF solution was measured and the coating effect of SF solution was tested. Polypropylene resin and polyurethane were used respectively to modify SF by cross blending. Through structural analysis of cross blend films with different proportion, the relations between structure & properties and proportion were researched. And the better proportion and preparation method were made sure by coating experiment of cross blending finishing agents The SF solution prepared by NaSCN solution tends to become gelatin, and the one prepared by CaCl2·H2O·C2H5OH can be stored for a longer time. The crust leather coated by SF solution cannot obtain good effects because SF permeated into leather too much. And coated by SF gelatin, it can obtain good handle and luster, but the fastness is weak. The mechanical properties of pure SF film shows that SF solution cannot be used as finishing agent directly. The properties of SF modified by the polypropylene resin have been improved. The flexibility of the film improved with the increasing of polypropylene resin, In coating experiments of crust leather, the effect of felt fastness became better, but the handle and luster were not good. The reason is probably that SF permeated into the leather. In coating leather, which was handled first, the handle and luster became nicer, but the felt fastness was weak. When the content of SF is 50%～75%, the new agent has a good property. The SF modified by polyurethane also improved SF film's properties. Polyurethane and SF have good compatibilities due to the action of hydrogen bonds. In coating leather, the effect was almost the same to that of the SF modified by polypropylene resin. The new agent shows better property when the content of SF is about 50%,. In this research, the SF is certain to improve leather's surface effect, including handle and luster. But the new agents obtained by modifying SF haven't been up to the mustard completely. And there are further research work to be done.