Crosslinking Agents for Water-based Polymeric Formulations

Several modifications can be introduced in standard formulations in order to improve the performances of adhesives or paints. In particular different approaches were used to improve the water resistance, the creep value and the heat resistance properties of poly(vinyl acetate) adhesives water based[1-3]. Generally the contemporary presence of NMA, as a crosslinking agent in PVAc polymers, and of AlCl3, as a catalyst and chelating metal salt, improves the water resistance of the adhesive joint. However, these modifications may cause some side effect such as formaldehyde emission or the yellowing of the adhesive joints upon heating or ageing [2]. Now we have studied crosslinking reactions of different vinyl acetate copolymers in order to obtain important information for produce new adhesive formulations (Figure 1). Modified PVAc with a higher co-monomer/VAM ratio (0.1) have been synthesised and their reactivity with different crosslinking agents has been analysed using FT-IR and NMR spectroscopies. This analytical procedure has been also used to study the crosslinking reactions of the poly(vinyl alcohol) used as protective colloid in poly(vinyl acetate) water dispersions. The crosslinking mechanism and the role of the main components of a PVAc-based adhesive formulation have been investigated. References [1] Qiao, L.; Easteal, A.J.; Bolt, C.J.; Coveny, P.K.; Franich, R.A Pigment & Resin Technology 2000, 29(3), 152. [2] L A. Salvini, L. M. Saija, S. Finocchiaro, G. Gianni, C. Giannelli and G. Tondi, J. Appl. Polym. Sci. 114 3841 (2009). [3] H. Tawada, T. Okamatsu, T. Kamikaseda, K. Yoshishu – Nippon Setchaku Gakkai Nenji Taikai, 39 (2001) 67.