【作者】 卢行芳；

【导师】 石碧；

【作者基本信息】 四川大学 ， 皮革化学与工程， 2002， 博士

【摘要】 本论文以牛皮为原料皮，研究了过氧化氢用量、脱毛液pH值、脱毛液温度、液比及过氧化氢加入速度等因素的变化对过氧化氢脱毛效果的影响规律。分析了脱毛废液中羟脯氨酸和氮含量与过氧化氢用量间的关系。通过检测废液中各种指标、铬鞣效果和坯革性能将过氧化氢脱毛方法和传统的硫化钠脱毛方法进行了比较，并观察了生皮和革的结构在使用不同脱毛方法时的区别，从组织学角度找到了过氧化氢脱毛的原理。 利用红外光谱技术分析了生皮中几种典型氨基酸在其与过氧化氢的碱性溶液作用后所发生的结构变化；分析了过氧化氢碱性溶液的作用对生皮的等电点、收缩温度及生皮胶原模拟物明胶的玻璃化温度的影响趋势。研究结果表明： 脱毛液pH值、过氧化氢用量的变化对过氧化氢脱毛效果影响最大，当脱毛液pH值高于12.5并且过氧化氢用量大于皮重的7.0％时，脱毛效果明显增强；脱毛液温度控制在25℃较宜，偏高或偏低均会使脱毛效果下降。较小的液比和较快的过氧化氢加入速度均对脱毛有着促进作用。但从废液中羟脯氨酸含量来看，过氧化氢用量不宜大于皮重的9.5％。 与传统硫化物脱毛方法相比，过氧化氢脱毛法不仅能降低脱毛废液的COD、硫化物、氨氮、悬浮固体含量，提高铬鞣革中Cr₂O₃含量和增大坯革的抗张强度，而且使真皮内毛根去除干净，胶原纤维分散快，革的粒面层与网状层间联结紧密。过氧化氢脱毛时毛由根部开始溶解。 过氧化氢脱毛时，毛中胱氨酸、皮板内丝氨酸、苏氨酸等发生结构变化， 四川大学博士学位论文从而使毛的碱溶解性增大，生皮等电点被降低，生皮收缩温度及明胶玻璃化温度被提高。更多还原

【Abstract】 In this paper, the factors influencing hydrogen peroxide unhairing of cattle hide and the mechanism of the process were studied. The effects of hydrogen peroxide offer, pH value, temperature, float and added rate of hydrogen peroxide on efficiency of unhairing were investigated. Contents of hydroxy-proline and nitrogen in waste water were determined by colorimetry and Kjeldahl procedures so that the relationship between hydrolytic degree of hide protein and unhairing condition could be observed. The comparison of hydrogen peroxide unhairing and conventional sodium sulfide unhairing was made based component analysis of waste water, effectiveness of chrome tanning and physical properties of resultant leather. Meanwhile the influence of two unhairing techniques on microstructure of hide or leather in processing was researched by histological observation and the histological mechanism of hydrogen peroxide unhairing was elucidated.To obtain further information of chemical mechanism, a series of typical ammo acids existing in hide collagen were treated with alkali hydrogen peroxide solution in the condition similar to unhairing process, and the change of their structure was determined by IR. Furthermore, the influences of alkali hydrogen peroxide solution on isoelectric point (IP) and shrinkage temperature (Ts) of hide and glass transition temperature (Tg) of gelatine were studied.The trials above indicated that the offer of hydrogen peroxide and the pH value of float were the main factors affecting unhairing result. When pH value was 12.5-13.0 and hydrogen peroxide offer was more than 7.5% based on hide weight, hair could be easily removed. But when hydrogen peroxide offer was more than 9.5%, hide collagen would be damaged evidently. Suitable temperature of float was 25C; incomplete unhairing would be observed when lower temperature was used. A short float and a faster added rate of hydrogen peroxide were favourable to unhairing.Compared with sodium sulfide unhairing, the unhairing with hydrogen peroxide could produce decreased contents of COD, S2", NH3-N2 and suspended solid in waste water; the content of S2- was particularly elimitated. It was also found that unhairing with hydrogen peroxide could increase content of Cr2O3 in leather after chrome tanning and improve tensile strength of crust. During unhairing, hair root was dissolved at the first, then hair was completely removed. At the same time, collagen fibers of hide were effectively dispersed. A distinct advantage of using hydrogen peroxide was that the connection of grain and reticular layers could be enhanced which could reduce loose grain of resultant leather.Reacted with hydrogen peroxide, some of cystines in hiar were derived into sulfide or sulfonate, leading to hair removing. Alcoholic hydroxyl of serine in hide collagen was oxidized into carboxyl group, and that of threouine was oxidized into acetaldehyde which could link with free amino group of protein. The linkage between protein fibers was verified by increased Ts of hide and raised Tg of gelatine. Both the derivation of alcoholic hydroxyl into carboxyl group and the linkage interaction of free amino group led to lower IP of hide, as observed.更多还原