A pass-through metal salt tanning method based on ultrasonic and microwave assistance

Abstract

The invention provides an ultrasonic wave and microwave assisted pass-type metal salt tanning method. The method comprises the following four steps: (1) regulating the pH value of pickled pelt firstly to be at least 3.5, extruding by adopting a roller type extruding machine, and regulating the distance between the extrusion rollers to be 40%-60% of the initial thickness of the pickled pelt; (2) enabling the grain side of the pickled pelt after extrusion to face downwards to pass through a metal salt tanning solution containing sodium chloride, tanning under the action of 40 KHz ultrasonic waves for at least 1 min, extruding the crust leather by adopting the roller type extruding machine, and further regulating the distance between the extrusion rollers to be 40%-60% of the initial thickness of the pelt; (3) repeating the operations in the step (2) for 1-3 times, and no longer extruding by adopting the roller type extruding machine after the last time tanning; and (4) performing heat preservation on the crust leather after the completion of operations in the step (3) in a microwave field for at least 2 min at the heat preservation temperature of 30-60 DEG C. The ultrasonic wave and microwave assisted pass-type metal salt tanning method is applicable to tanning adopting various metal salts, the tanning time is short, and the physical and chemical property of the obtained leather have no obvious difference compared with that obtained by adopting the conventional method; besides, the tanning solution in the method is recyclable, and waste water containing a tanning agent is not discharged during the tanning process.

Description

technical field [0001] The invention belongs to the technical field of leather processing, and in particular relates to a through-type leather inorganic metal salt tanning method based on ultrasonic waves and microwaves without using drums. Background technique [0002] Tanning is the most important process in leather processing. After tanning, raw hide can be transformed into leather. Compared with raw hide, leather is more resistant to heat and humidity, better in chemical resistance and biodegradation, will not swell in water, and has certain formability, good air permeability, bending resistance and plumpness after drying. It is an excellent material for making shoes, clothing, furniture and bags. [0003] Generally speaking, tanning methods are divided into three types: inorganic tanning, organic tanning and combined tanning. Inorganic tanning is the use of metal salt tanning agents to tan bare hide and convert it into leather. At present, the tanning operation in th...

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Problems solved by technology

However, although the chrome tanning solution can be reused in this method, after using the lye for a certain number of times, it cannot be reused due to the accumulation of chromium in the solution. The discharge of this part of the liquid makes this method unable to achieve zero chrome tanning Chromium emission (Chinese invention patent: an ultrasonic-assisted four-bath chrome tanning method with penetration and fixed separation. Patent authorization number ZL 201310295195.2)

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