A kind of formaldehyde-free amino resin retanning agent

Abstract

The invention discloses a formaldehyde-free amino resin retanning agent. The formaldehyde-free amino resin retanning agent is characterized by being formed as follows: firstly, obtaining an intermediate containing hydroxyl and aldehyde group residue in molecule by using an amino monomer and glutaraldehyde through nucleophilic addition; then, obtaining the formaldehyde-free amino resin retanning agent by a series of reactions such as sulfonation, hydrolyzed collagen end-blocking, condensation and etherification. The formaldehyde-free amino resin retanning agent provided by the invention is an amino resin condensation product containing an aldehyde group, has retanning performance comparable with that of the conventional amino resin retanning agent, has an aldehyde group capable of performing covalent cross-linking reaction with the amino on collagenous fiber in molecule, and can be used for improving the humidity and heat-resistant stability of finished leather. Formaldehyde is not used in a preparation process of the formaldehyde-free amino resin retanning agent, so that harms of formaldehyde in the finished leather can be greatly lowered.

Description

Technical field [0001] The invention belongs to the technical field of retanning agents for tanning leather and fur, and specifically relates to a new formaldehyde-free amino resin retanning agent. Background technique [0002] Amino resins are widely used in the leather industry due to their good leather filling properties and better dyeing properties. Amino resins are usually the condensation products of melamine, dicyandiamide, urea and other amino-containing monomers with aldehydes (mainly formaldehyde). Since the reaction between amino-containing monomers and formaldehyde under alkaline conditions is reversible, a certain amount of free formaldehyde will inevitably exist in such products or during product use, and the presence of formaldehyde will seriously harm people's health. With the continuous improvement of people's living standards and the need for environmental protection, more stringent limits have been put forward for the content of formaldehyde in leather. Common...

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Problems solved by technology

For example, the formaldehyde in the methyl etherified amino resin product can be removed by vacuum dehydration, methanol removal and formaldehyde in the later stage of the reaction (Yan Xinning, Wang Guanzhong, Shi Qingxue, etc. A kind of low free formaldehyde methyl etherified melamine formaldehyde resin crosslinking agent Synthetic method [P].CN101817914A, 2010-09-01), but the effect of removing aldehyde is not obvious; Adding formaldehyde scavenger in the later stage of reaction is an effective and direct method, but commercially available formaldehyde scavenger is generally more expensive, And the use of formaldehyde scavenger will reduce the use performance of finished leather, so the use of formaldehyde scavenger is subject to certain restrictions

In addition, although the low-formaldehyde amino resin retanning agent product has undergone formaldehyde removal treatment, formaldehyde is used as the starting material in the synthesis process, and the methylene ether bond formed by the condensation of formaldehyde is unstable, so it will continue to be released during use. Free formaldehyde (Gu Jiyou. Adhesives and coatings [M]. Beijing: China Forestry Press, 1999),

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