Effects of ASRs, alkali neutralizers and crosslinking reaction on the application properties of self-crosslinking polyacrylate latex binders

• Published in: Progress in organic coatings Vol. 197; p. 108851
• Main Authors: Li, Shoujia, Liu, Jie, Zhang, Xinyi, Ye, Jun, Mu, Yuanchun, Wang, Haiqiao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024
• Subjects: Alkali neutralizer; Alkali-soluble resin; Crosslinking reaction; Polyacrylate latex; Property; Crosslinking reaction; Alkali neutralizer; Polyacrylate latex; Property; Alkali-soluble resin
• ISSN: 0300-9440
• DOI: 10.1016/j.porgcoat.2024.108851

In this contribution, three types of alkali-soluble resins (ASRs), Joncryl 678, Joncryl 67 and Joncryl 692— with similar acid values but different molecular weights were selected as surfactants, respectively, and diacetone acrylamide (DAAM) and adipic acid dihydrazide (ADH) were used as crosslinking systems to synthesize self-crosslinking polyacrylate latex binders L-678, L-67 and L-692, for water-based inks. The three ASRs have the same critical micelle concentration (CMC) but different surface tensions at CMC, with J678 having the lowest surface tension. In addition, the L-678 latex exhibits the most suitable shear thinning properties and the lowest viscous flow activation energy, indicating that J678 is the most suitable surfactant for preparing polyacrylate latex binders among the three ASRs studied. The degree of neutralization of J678 determines the degree of stretching of its molecular chains in water, which in turn affects its solubilising effect on monomers, resulting in corresponding latexes of different finenesses. The pKa and volatility of the alkali neutraliser influence properties such as re-solubility, drying performance, and storage stability of the corresponding latex. Increasing the amount of DAAM helps to increase the crosslink density of the latex film and reduce the phase separation between the core and shell. However, due to the largely uncrosslinked shell layer formed by the ASRs and the inhibitory effect of this thick shell layer on the DAAM/ADH crosslinking reaction, these latexes exhibit a low degree of crosslinking. [Display omitted] •The type of ASR affects the rheological properties and stability of the corresponding latex.•The pKa and volatility of the alkali neutraliser have a great influence on the properties of the latex and its inks.•The shell layer formed by alkali-soluble resins is the main reason for the low cross-linking of latex films.