Development Of Antimildew System For Water-based Coating - 50% Antimildew Suspension Concentrate

In order to explore different factors on the physical storage stability of the antimildew suspension concentrate, guide the choice of antimildew component, construct excellent antimildew suspension system, the physical storage stability of 50% antimildew compound suspension concentrate were studied by the performance evaluation of several major novel wetting-dispersant, thicken agents and the processing technic.The paper tested the antimildew effect of single fungicide through the experiment of minimum inhibitory concentration (MIC). The results showed that most of the fungicides were less antimildew effective to the tested mildews. Combined with our previous analysis experience of some mature foreign products formulation, we used the method of trial and error procedure to make dual and ternary mixtures of fungicides. And then we tested the MIC values of the dual and ternary mixtures of fungicides. The results showed that the antimildew effect of dual mixtures of fungicides improved slightly with the premise of maintaining the lowest cost. However, the ternary mixtures of fungicides played excellent antimildew effect. Considering the factors of antimildew effect, cost and the compatibility with the water-based coating, we chose the ternary mixtures of fungicides (BDY:B03:D05=5: 50:45) as the active ingredient of the antimildew suspension concentrate.The choice of wetting-dispersant was the major factor in affecting the physical storage stability of antimildew suspension concentrate. Integrating flow point method and trial method with the choice of thickeners, several wetting-dispersants were estimated by mensurating the major technical parameters of suspension concentrate.The determination results of the dispersants' flow point showed that the performance of modified alkyl sulfate/sulfonate anionic surfactants were better than the surfactants of sulfosuccinate salts. As an anionic surfactant, the flow point of D-1002 against the tested fungicides was the lowest. In order to further improve the performance of dispersants, we selected anionic and non-ionic surfactant to make dual dispersant mixtures and tested their performance. The results showed that the flow points of non-ionic/anionic surfactant complex were lower than the single one, indicating that the surfactant complexs had the role of synergies. Combined with the situation of actual production and the price of raw materials, we selected 603/D-1002 as the wetting-dispersant in our experiment. Then we ascertained the best type and amount of thickener by adding the thickeners to the antimildew suspension concentrate. The optimal formula of the antimildew suspension concentrate was determined as follow. The active ingredient was the ternary mixtures of fungicides (BDY:B03:D05=5:50:45). The wetting-dispersant was the dual dispersant mixtures (603/D-1002). And the thickeners included 0.8% hydroxyethyl cellulose,0.3% xanthan gum and 0.3% aluminum magnesium'silicate. Water was added up to 100%.The effects of different millers and different milling time to the grinding efficiency and physical storage stability of antimildew suspension concentrate were studied. The relationship between the milling time of suspension concentrate formulation processing and the average particle size and size distribution in suspension was studied. We also investigate whether milling technics and milling time affected the properties of suspension physical stability and suspension viscosity. The result showed the physical stability of suspension concentrate became better and the particle size and size distribution (percentage of particles<3μm) decreased with increase of the milling time, when the suitable adjuvant and processing conditions were selected. The increase of the viscusiry of the suspension and smaller particle size would be more helpful to physical stability of the suspension. Under the same conditions, the grinding efficiency of horizontal grinding machine was higher than the vertical grinding machine.We studied the antimildew effect of water-based coating films adding the antimildew suspension concentrate. The blank coating sample was less antimildew, and the antimildew rating was 3rd. The coating film added the mildew preventive had strong antimildew effect, and the antimildew rating was 0. We studied the effect of the paint coating applied in natural practical outdoor environment after 1 year. The powdering and shedding phenomenon of the coating had not fungicides was obvious, and there were some visible fungi spots scattered on the coating film surface. However, the powdering and shedding phenomenon of the coating with 0.5% fungicides was not occur, indicating that the antimildew effect of the coating with 0.5% fungicides was still excellent after the natural aging. Therefore, the application of 50% antimildew suspension in water-based coating showed well.The antimildew suspension concentrate is a very complex system. There is considerable variability in the performance of different additives. In the research of antimildew suspension concentrate, we should still select the correlative adjuvants and processing technic by lots of experiments. But the mechanism study of physical storage stability of antimildew suspension concentrate must be helpful to the development of antimildew suspension concentrate, combing with the research of the adsorption of dispersant in fungicides and the rheology property of antimildew suspension concentrate.