Preparation of reactive amphoteric polyurethane with multialdehyde groups and its use as a retanning agent for chrome‐free tanned leather

Abstract

Leather retanning agents are of great meaning for the reactive competence and thermal, physical, and mechanical properties of treated leather fibers. For this motif, reactive amphoteric polyurethane with multialdehyde groups (AAPU) was prepared by a polyaddition reaction with isophorone diisocyanate, poly(tetrahydrofuran glycol), 2,4-dihydroxybenzaldehyde, 2,2-dihydroxymethyl propionic acid, and N-methyl diethanolamine as raw materials and was then used as a retanning agent to explore its effects on leather fibers. The structure of AAPU was confirmed by UV, Fourier transform infrared, and 1 H-NMR spectroscopy. An average particle size of 42.6 nm and an isoelectric point of 5.16 were determined. The thermal stability, physical and mechanical properties, and morphology of the AAPU-treated leather fibers and their reactivities to anionic materials were investigated. Because of the crosslinking effect of multisite covalent bonds, which resulted from reactions between the aldehyde groups in AAPU and the pendant amido groups from collagen fibers, and the role of the cationic groups in AAPU, the thermal stability of the treated leather fibers and their reactivity to anionic materials, such as dyestuffs and fatliquoring agents, were enhanced. Thus, the absorption rate of dyes was almost as high as 99.89%, and the physical and mechanical properties of the AAPU-treated final leather fibers were superior to those of the contrast.

Amphoteric functional polymers for leather wet finishing auxiliaries: A review

“…As shown in Figure 7(A), in the synthetic route for the reactive AAPU. Xu Wei 40 prepared a novel type of amphoteric polyurethane retanning agent with multialdehyde groups (AAPU) by a polyaddition reaction with isophorone diisocyanate (IPDI), poly(tetrahydrofuran glycol) (PTMG), 2,4‐dihydroxybenzaldehyde (DDBA), 2,2‐dihydroxymethyl propionic acid(DMPA), and N ‐methyl diethanolamine ( N ‐MDEA) as raw materials. In the whole reaction process, we can find the amphoteric polyurethane retanning agent with multialdehyde groups is obtained by two major reaction steps.…”

“…(A) Synthetic route for the reactive AAPU and TEM images of the AAPU latex particles; (B) Comparison of photographs of liquors and the samples before and after dyeing: (a') Acrylic resin retanning agent treatment and (b') AAPU retanning agent treatment; (C) Physical and mechanical properties of the crust leather fibers. Reprinted with permission from Reference 40. Copyright 2019, Wiley, Periodicals, Inc…”

Catalytic Mannich reaction of acrylic acid polymers and their application in leather retanning

“…1–3 Such polymers are used in synthetic rubber, synthetic fibers, super-absorbent resins, pharmaceuticals, leather, textiles, building materials, water treatment, oil exploitation, coatings, and other industries. 4–10…”

Effect of cationic monomer structure on the aggregation behavior of amphoteric acrylic polymer around isoelectric point

“…According to structures, amphoteric polymer retanning agents are classified into amphoteric acrylic polymer [11][12][13], amphoteric polyurethane [14,15], amphoteric syntan [16], etc. Among them, amphoteric acrylic polymer (AAP), which is a linear polymer synthesized by free radical co-polymerization of anionic acrylic monomers and cationic acrylic monomers, is the most widely used type.…”