Effect of Molecular Weight of Acrylic Resin Retanning Agent on Properties of Leather

The effect of molecular weight of acrylic resin retanning agenton its penetration in leather and the properties of the retannedleather were investigated. After retanning chrome tanned leatherby four fluorescent acrylic resins with different weight-averagemolecular weights (Mw) from 5,000 to 200,000, it was observedthat the Mw of acrylic resins was not the main factor influencingtheir penetration in leather. In fact, the dosage of acrylic resinand the charge of leather were more important factors affectingpenetration rate. Additionally, an increase in the Mw of acrylicresin led to an increase in the thickness of leather and a decreasein the softness of leather, which is mainly because the acrylicresins with higher Mw can enter larger gaps between collagenfibers and exhibit a better filling effect. Moreover, when acrylicresins were used together with other anionic retanning agents inretanning process, the penetration and distribution evenness ofacrylic resins were remarkably improved, and meanwhile theacrylic resins with different molecular weights presented nearlythe same effect on properties of resultant leathers.