Synthesis And Application Of PVAc-NMA Co-Polymerization Emulsions

Polyvinyl Acetate(PVAc) emulsion has many characteristics, such as single-component, non-poisonous and non-harmful, hardly burning and bursting, easily production, low price, convenience application, saving resources etc., so it's widely applied in bonding of many porous materials, for example, wood processing, furniture packaging, buildings decoration, textures bonding, prints binding and so on. It's considered as a green and environmental protection adhesive. However, the cost of Vinyl Acetate(VAc) is a little higher, and the cold-resistance, hot-resistance, water-resistance, mechanical stability and storage stability of PVAc are poor. Therefore, the modification of PVAc is a key point to develop and study for domestic or foreign scholars. In addition, N-Hydroxymethyl Acrylamide(NMA) is an effective cross-linking monomer, and can polymer with VAc to develop the co-polymerization emulsion system of PVAc-NMA. The molecule chains of PVAc-NMA possess active groups hydroxymethyl, which can condense with the hydrogen atom in amino or sub-amino under certain condition, then develop a new sub-methyl bridge bond and produce a water molecule, thus the application and modification of PVAc are expanded.The main work of the paper included:1. The synthesis and performance assessements of PVAc, PVAc-NMA and PVAc-NMA-Urea were studied, specifically including the synthesis craft, the stability, the filming, the surface wetting, the hardening and others, and the performances influenced by the different quantities of NMA and urea were discussed, too.2. The formulation, performance assessements and whole set application thchnolgy of PVAc-NMA used in the hardener for Urea-Formaldehyde(UF) resin were studied, specifically including the hardening of UF, the formaldehyde emission and bond strength of hot-pressed plywood, the cost budget and the industry production practices.The main conclusions on the synthesis of PVAc-NMA were as follows:1. The absorbing water rate and water resistance of PVAc were greatly improved by adding NMA; The absorbing water rate of PVAc-NMA was the lowest when m(NMA):m(Vac)=0.1:100, and the water resistance(The tackless time on 80℃) was the best when m(NMA):m(VAc) = 1.0:100, 0.37 times and 7.97 times that of PVAc respectively, but the improvements declined instead when NMA added more than some.2. The viscosity and stability of PVAc-NMA increased generally according to the adding of NMA, the polymerization and machinery stability were the highest when m(NMA):m(VAc)=2.0:100 and m(NMA):m(VAc)=0.1:100 respectively, 1.94 times and 1.69 times that of PVAc; Meanwhile, the bond strength and solidifying rate of PVAc-NMA also did so, the dry and wet strength were the highest when m(NMA):m(VAc)= 1.0:100,...