Study On Preparation And Properties Of Waterborne Anti-microbial Coatings

With the increasing of global population, the wanning of the climate and the pollution of environment, people are prone to be attacked by bacteria and various at any moment. The "SARS" in 2003 and "bird flu" in recent years are a case in point, which have caused great loss of people's lives and property. In order to improve people's health, and their living and working conditions, it is one of the researchers' major projects to explore and develop a new-type anti-bacterium material with high efficiency, innocuity, tasteless, and lasting anti-bacterium capacity. Waterborne polymer anti-bacteria paint with high efficiency, broad-spectrum, low toxin, tasteless, non-pollution and the like, which is taking the place of the anti-bacterium paint which intermingle small molecule.A serious of polymer emulsions of core-shell structure containing high hydroxyl content have been synthesized with semi-continuous seed emulsion polymerization methods, using butyl acrylate, styrene, hydroxylethyl methacrylate and acrylic acid as monomers. The hydroxyl component of above polymer emulsions came from styrene acrylic emulsions, styrene acrylic antibacterial emulsion and Ag~+-MMT-modified styrene acrylic antibacterial acrylic emulsion. That is, The influence of the composites of these emulsions on polymerization process, viscosity, particle size and coagulum are investigated. Infrared spectroscopy(IR), nuclear magnetic resonance, (NMR), transmission electron microsoopy(TEM) and thermogravimetric analysis (TG/DTA) are used to characterized their structure, composite, morphology and thermal stability, respectively. Combined with hydrophilically-modified poly-isocyanate at proper NCO/OH, ratio, the film properties of two-component waterborne polyurethane paints are studied from varying their composites and ratio, surface morphology and molecular structure of these films are observed with scanning electron microscopy (SEM), nuclear magnetic resonance, (NMR) and IR spectroscopy. Antimicrobial properties were studied by SYNBIOSIS auto-detect microbe apparatus, It show better antimicrobial activity on escherichia coli and golden Staphylococcus. From these experiments we may come into these conclusions:1 " Particle core-shell Structure Designing" were used in semi-continuous seed emulsion polymerization. The preparation methods of polymer emulsions with core-shell structure containing high hydroxyl content were studied for the first time. Optimum conditions of technologies were obtained: 1% of SDS/OP were used as mixed emulsifiers. The ratio of SDS/OP was 4/6 at 75℃. The total amount of ST and BA was kept at 5%, respectively, and BA/ST weight ratio in core was kept at 2/1. the polymerization process had lower coagulum. Compared with emulsion without core-shell structure, when the hydrophilic monomer was not used in core composite, coagulum had decreased greatly and the amount of emulsifier may be reduced. The enwrapping core-shell structure was clearly appeared in TEM.2 The antibacterial emulsions containing high hydroxyl content and having core-shell structure were synthesized for Two-component waterborne polyurethane antibacterial paint. The results are as follows: SLS/OP as mixed emulsifiers, its level at 3.0% with ratio 4/6. The emulsions were synthesized at 60℃, level of antibacterial monomers is all 5%. It has shown hemisphere core-shell structure through the TEM photos. The antibacterial activity of the polymer was evaluated through the SYNBIOSIS auto-detect microbe apparatus. It exhibited optimum antibacterial activity against escherichia coli and golden Staphylococcus.3 We have prepared the styrene-acrylic-butyl antibacterial emulsions with core-shell structure which were modified by Ag~+-MMT for the first time. The level of Ag~+-MMT was 3%, The heat deposited stability and the antibacterial activity were characterized. It has shown optimum heat deposited stability and antibacterial activity.4 Two-component waterborne polyurethane antibacterial paint(TCWPAP), which composed by styrene acrylic antibacterial emulsion and hydrophilically-modified polyisocyanate. It has good adhesion, flexibility, impact resistance, and also good water and chemical-resistance. Dry time becomes longer as the increase of emulsifier level and NCO/OH ration, the gloss decrease as the increase of emulsifier level and particle size. The film has different hardness at 48h at different NCO/OH ratio, but comes to same hardness after 7 days, although hardness develops slowly at lower NCO/OH ratio. The film has best water and chemical-resistance when the hydroxyl value is 100 mg KOH/g, and NCO/OH ratio is 1.5:1 and lower emulsifier level. The antibacterial activity of the polymer was evaluated through the SYNBIOSIS auto-detect microbe apparatus. The experimental results showed that the functionalization degrees with antibacterial coating were 0-1.That is, it has optimum antibacterial activity.5 The properties of the two-component waterborne polyurethane antibacterial paint(TCWPAP- Ag~+-MMT), which composed by Ag~+-MMT nanoparticles modify emulsion and hydrophilically-modified poly-isocyanate, have been prepared. It is concluded that the antibacterial paint showed good adhesion, flexibility, impact resistance, and also good water and chemical-resistance. With increasing of content of Ag~+-MMT, the dry time becomes longer than that of TCWPAP, the luster was decreased. The antibacterial activity of the polymer was evaluated through the SYNBIOSIS auto-detect microbe apparatus. The results showed that the functionalization degrees with antibacterial coating were zero. It means that TCWPAP- Ag~+-MMT can be used as paint with high antibacterial activity.