Preparation And Properties Of One Component And Cationic Waterborne Pacrylic/alkyd Resin Coating For Wood

Alkyd resins are polyester resins that are derived from natural materials. It has much advantage of low price, convenient construction, high glossiness and good film-forming ability. Therefore, it has become one of popular coatings. However, based on requirement of environment, slow drying and poor weather resistance, waterborne alkyd resins have been an important material choice for coatings. In order to solve above problems, this topic is to prepare a waterborne alkyd resins coating with good properties by combing advantage of acrylic resin.At first stage of this paper, a series of one component cationic acrylic/alkyd coating emulsion(CPAAR) was prepared by free radical solution polymerization technique and emulsification process, using methyl acryloyl oxygen ethyl methyl ammonium chloride(DMC), methyl methacrylate(MMA), butyl acrylate(BA) and alkyd resin(AR) as reaction monomers. The effects of amount of hydrophilic monomer DMC, content of alkyd resin AR, mass ratio of hard monomer MMA and soft monomer BA and preparation technique on particle size, water absorption and glossiness of emulsion and films was discussed in detail. The structure of CPAAR polymer and emulsion morphology were investigated by fourier transform infrared spectroscopy(FTIR), nuclear magnetic(NMR) and transmission electron microscopy(TEM). Besides, the stability, glossiness, solvent resistance and other performance properties of emulsion and films were also investigated.And then a series of cationic acrylic/alkyd resin coating was successfully prepared using CPAAR emulsions, titanium dioxide, dispersant, thickener and defoamer as raw materials. The influence of amount of dispersant, dosage of thickener, dosage of defoamer, content of titanium dioxide, preparation technique and coating process on stability, water absorption and glossiness of CPAAR coating was systematically studied. The rheological property, thermal property, surface morphology and glossiness of coating were characterized.(1) The appropriate formulation and properties of one component cationic acrylic/alkyd emulsion was systematically investigated. The results showed: wt(DMC)=5.08%,wt(AR)=40%,m(MMA)/m( BA)=12:3, by adding AR at the initiative stage of reaction, particle size of CPAAR emulsion was 216.2 nm, DPI was 0.134, water absorption was 1.452%,Td,5% was 185.7 ℃, Tg was 26.8 ℃, glossiness was 116 and hard drying time was 6 day. And the emulsion has good stability, thixotropic property and slight yellowing phenomenon on non-iron substrate.(2) The structure of polymer was characterized. The FT-IR and NMR results proved in agreement with the chemical structure of product designed. Molecular weight of alkyd resin was: Mn=2741, Mw=4291, Mw/Mn=1.566 and that of acrylic resin was: Mn=86891, Mw=122787 and Mw/Mn=1.413. The TEM test indicated that the latex particles exhibited as core/shell spherical morphology.(3) The appropriate formulation and properties of one component cationic acrylic/alkyd coating was systematically detected. The results showed: wt(dispersant)=3%,wt(titaniumdioxide)=15%,wt(thickener)=1%,wt(defoamer)=1%, by adding dispersant during dispersive process and carrying pretreatment on wood substrate, precipitation rate of CPAAR coating was 2.5%, water absorption was 5.8%,Td, 5% was 215.3 ℃, Tg was 32.8 ℃, and glossiness was 82. And the coating also has good stability, thixotropic property and concavoconvex structure with surface roughness of 3.893 nm.