Mechanical Blending Preparation of Hydrophilic Spherical Nano-SiO2/Acrylic Resin Nanocomposite for Tanning Leather

Abstract

In this study, the spherical silica nanoparticles (denoted as PASP-K-SiO2) were firstly prepared with 3-aminopropyltriethoxy silane (KH550) and polyaspartic acid (PASP) as surface-modifiers by sol–gel method. The PASP-K-SiO2 nanoparticles were well dispersed in water and combined with waterborne acrylic resin matrix (denoted as PAA) for preparing novel nanocomposite tanning agents (denoted as PASP-K-SiO2/PAA) successfully through a strong mechanical blending. The nanocomposite tanning agents were used to tan pickling white-wet sheepskin and the tanned leather was characterized by rheological measurements, revealing an increase in the storage modulus and relaxation time of the leather compared to the leather tanned with bare nano-SiO2 and neat PAA. The leather tanned with PASP-K-SiO2 nanoparticles also exhibits excellent mechanical properties, high thermal stability and chromium absorption rate. Moreover, the shrinkage temperature of the leather tanned with PASP-K-SiO2/PAA and just 0.2% chromium powder based on the sheepskin weight can reach above 80 C, which is potentially advantageous in completely or partially replacing toxic chromium tanning agents used in traditional leather industry. Compared with the chromium tanning process, the tanning method with the nanocomposites would be regarded as eco-friendly, thus contributing to the reduction of environmental impact.