| Liquor from tannery unhairing process contained large amounts of solublekeratin, it could cause high value of BOD and COD if it was emissioned directly,and it could cause serious contamination if it was not recycled. In addition, theraw material of modified casein finishing agents on the market was limited, sothe price of it was too high. In view of the situation, the preparation of modifiedkeratin finishing agents from tannery unhairing liquor had been stuied in thearticle.The keratin was recycled from tannery unhairing liquior by the method ofprecipitation at the isoelectric point, and then it was characterized by GPC, IR,DSC and so on. The results showed that, the number molecular weight of maincomponent in keratin was was3399, and the polydispersity was1.0000，themolecular weight was moderate. So the recycled keratin had the value to beutilized. And then the characteristic absorption band of acylamino could beobserved in IR spectrum，which indicated that,the recycled keratin retained theoriginal structure of keratin. The analysis of DSC-TG showed,the thermalstability of keratin was good below224.1℃. And then the dimaeter and Zetapotential of keratin aggregate was458.2nm and-17.29mv, the charge density andsize of keratin particle was a little bigger then casien. The contact angle ofkeratin was48.3°, the water resistance was poor compared with casein.In order to prepare the keratin derivative, the addition reaction of glycidylmethacrylate (GMA) and keratin happened. The best preparation condition ofkeratin derivative was obtained by determing the content of C=C.when thetemperature was50℃, pH was7.5and the weight ratio of GMA to keratin was0.1, the content of C=C of keratin derivative was maximum. The karatinderivative was characterized and the results showed that: A new absorbtion bandof ester group appeared in IR spectrum, which confirmed the introduction ofGMA onto derivative. The analysis of DSC-TG showed that, the thremal stability of derivative was improved by the introduction of C=C and ester formGMA. And the Zeta potential of derivative particle was-1.356mv, chargedensity was lower than karatin.The diameter of keratin particle was459.8nm,which showed that the small dosage of GMAcan not change the conformation.The contact angle of keratin derivative increased to53.0°, so water resistance ofit was a little improved by the introduction of ester group.The keratin derivative was copolymerized with mixed vinyl monomers ofbutyl acrylate (BA), styrene (St), acrylic acid (AA) and acrylonitrile (AN) by themethod of soap-free emulsion polymerization.The best preparation condition ofcopolymer was obtained by determing the viscosity: when the temperature was80℃, the time was60min, the pH value was measured by ammonia andtriethylamine, and the weight ratio of mixed monomers to keratin was0.7, theviscosity of keratin copolymer was maximum. The number molecular weight ofmain component in copolymer was11315, it was much higher than that ofkeratin,which indicated that the copolymerization degree was high.And then theintensity of the absorbtion band of ester group increased, new absorption band ofnitrile group and pheyl group appeared in IR spectrum，which showed that thegroup of monomers were introduced into derivative. After that a melting peak ofhard segment in ccopolymer appeared in the curve of DSC-TG, which indicatedthat the hard monomers was introduced.The diameter of copolymer particle was520.8nm, the size of it was much bigger than keratin, which confirmed moremonomers was grafted onto keratin. The contact angle of kerain copolymer risedto80.4°, so its water resisitance was improved by the grafting of hydrophobicmonomer.The physical properties of membrane were analyzed after the keratincopolymer membrane was prepared from the keratin copolymer. It showed thatThe tensile strength were12.37N/mm2, elongation at break and elongation atconstant load was87.50%and78.26%respectively.The toughness of copolymermembrane was much better than casein membrane, which showed the fragilityand weak fastness to wet rubbing of keratin were improved by grafting of BAand AN.The keratin graft copolymer emulsion was applied as the base finishingagent of leather, then the physical property and health performance of leather were determined. The results showed that: The flex resistance of leather was28000times, fastness to wet rubbing of leather was4grade. The flex resistanceelongation strength and fastness to wet rubbing were much better compared tothe leather finished by commerical product. And permeability to air was467.52ml (cm2·h), which was near to the commercial product. In a word, theproperty of the modified keratin finishing agent prepared by the author was goodand its price was low. |
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