Preparation method of aluminum-oxidized starch complex tanning agent

Abstract

A preparation method of an aluminum-oxidized starch complex tanning agent comprises steps of: first mixing starch and water, adding concentrated nitric acid and a catalyst, and stirring for reaction, washing reaction products with ethanol or acetone to obtain the oxidized starch; and evenly mixing the oxidized starch and aluminum ions, oscillating, steaming out excessive water by a rotary evaporimeter, and drying the obtained product. The method of the invention can effectively improve the tanning property of the aluminium tanning agent, maintain original advantages of the aluminum tanning agent and greatly mitigate the phenomenon of detanning. The method of the present invention employs nitrate as an oxidant to oxidize hydroxyl groups to generate oxidized starch with high degree of carboxylic substitution, and utilizes a principle of acid degradation to reduce the relative molecular mass of the oxidized starch, so as to obtain aluminum-containing macromolecular tanning agent with good permeability, high absorption rate and excellent tanning property. The obtained leather tanning agent has good tanning and filling performances, and is suitable for main tanning and retanning; after the main tanning, a pickled skin has a shrinkage temperature raised to 90 DEG C, gains pure white leather body and obvious thickness increase; and after retanning, a product has good elasticity, bright color, gloss, and soft and full handle.

Description

technical field

[0001] The invention relates to a preparation method of a natural polymer tanning agent, in particular to a preparation method of an aluminum-oxidized starch complex tanning agent. Background technique

[0002] Leather tanning agent is a chemical commonly used in the leather industry. At present, chrome tanning agent is mainly used in light leather production. It can endow light leather with excellent properties such as softness, plumpness, and high moisture and heat resistance. However, the trivalent Chromium can be slowly oxidized to hexavalent chromium in the process of use, which has potential carcinogenicity, and the environmental pollution and water pollution caused by it cannot be ignored. Therefore, it is very necessary to develop chrome-free tanning agents to reduce or replace chrome tanning agents. The starch tanning agent has the characteristics of mild reaction conditions, low energy consumption, and unique process in the preparation process. The...

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