Method for preparing acrylic acid retanning agent by using oxidation reduction system as initiator

Abstract

The invention provides a method for preparing an acrylic acid retanning agent by using an oxidation reduction system as an initiator. The method comprises the following steps of: adding 450 to 470kg of water into a pre-mixing kettle, adding 6.0 to 6.5kg of reducing agent while stirring the water, adding 1,250 to 1,300kg of acrylic acid, and mixing the mixed solution for 30 minutes; adding 1,670kgof hot water, of which the temperature is 85 DEG C, into a polymerization kettle, then adding 7.5 to 8kg of reducing agent, heating the materials in the kettle to between 92 and 96 DEG C, and adding 6.1 to 6.2kg of oxidant; adding the acrylic acid in the pre-mixing kettle dropwise, simultaneously adding 30 to 35kg of oxidant dropwise, wherein the adding time is 4 to 6 hours, and the temperature is kept between 92 and 96 DEG C in an adding process; after addition, adding 18 to 20kg of oxidant, continuously performing the reaction for 2 to 3 hours by controlling the reaction temperature to be 95 DEG C; cooling the products to between 50 and 60 DEG C, adding 300 to 315kg of 30-percent sodium hydroxide solution and 340kg of water, adding 950 to 970kg of 30-percent sodium hydroxide solution again, adjusting the pH value of the solution to 4.5 to 5.5, and controlling the temperature to be or be below 60 DEG C; adding 5.0 to 5.2kg of corrosion inhibitor, adding water to adjust the solid content to a defined index, and finally obtaining the acrylic acid retanning agent. The acrylic acid retanning agent is colorless and transparent, has a proper molecular weight and a good filling property, and can effectively increase absorption of chromium and reduce chromium content of waste water.

Description

technical field [0001] The invention relates to a preparation method of a retanning agent for tanning, more specifically, the invention relates to a preparation method of an acrylic acid retanning agent using a redox system as an initiator. Background technique [0002] Retanning is an important and indispensable process in the process of leather making, known as the "golden touch" of leather making. Retanning can improve the fullness and firmness of the leather, reduce the difference in parts, etc., and is also conducive to the operation of the subsequent finishing process. Acrylic polymer retanning agent has good water dispersion and good binding ability with leather, strong filling effect, obvious thickening effect on leather, and can also endow leather with good softness, fullness and elasticity. At the same time, the carboxyl group in the acrylic retanning agent has a strong complexing ability with chromium, so it can promote the absorption of chromium and have a fixat...

AI Technical Summary

Problems solved by technology

[0003] The acrylic retanning agent is mostly carried out by solution polymerization with water as medium, the reaction temperature is 70-80°C, and the initiator is ammonium persulfate or potassium persulfate. During the reaction process, it is easily oxidized by air and the color becomes darker. In order to obtain a colorless product, N 2 protection, cost