Preparation Of NO-VOC Elastic Styrene-acrylic Emulsion And Study Of Coating Properties

NO-VOC coatings are in which the content of VOCs can’t be detected by Existing detection methods. VOC emissions of coating has great harm to the environment and people’s health, so far. How to reduce VOC of coatings can’t be delayed. Compared to solvent-based coatings, residual monomers, coalescent and other additives are major sources of VOC in waterborne coatings. Optimized polymerization could be eliminated the residual monomers; Using core-shell polymerization technique, emulsion blend technology and micro-crosslinked coating technology to solve the contradiction between the mechanical properties and minimum film forming temperature, which can obtain excellent performance of NO-VOC latex coatings. Preparation and properties of NO-VOC coating elastic styrene-acrylic emulsion, is significant in practical applications.Main results:1) Using the new redox initiator FF6 M @ APS, both the ratio of 2:1, OP-10:SDBS is 1:2, the temperature from between 40 ℃to 65℃, stirring speed 300r/min, to core-shell emulsion polymerization. The results show: the initiator content of the monomer 0.50wt%, the emulsifier content of 6.00wt% monomer content, the polymerization temperature is 60℃, the monomer conversion rate is about 99.00%, the gel fraction is less than 0.50wt%, latex particle size of about 90 nm, in the latter part of the polymerization, a small amount was added again FF6 M @ APS emulsion curing period of time, conversion of the monomers near 99.99%.2) The results of the core-shell latex film-forming properties and mechanical properties of the coating show that: the MMA and St nuclear monomer, 2-EHA and BA to shell monomers, designed according to different proportions of different Tg polymer emulsion;and when ratio greater than 1 is equal to the hard and soft emulsion minimum film forming temperature are 0℃, Tg is less than the theoretical value 0℃; when the hard and soft ratio is 3:2, coating film had a pencil hardness HB, adhesion to 1, gloss is 71.6, a tensile strength of 0.60 Mpa, elongation at break of 821%; IR spectrum show a monomer content of the emulsion is 0; coating begins to decompose at 300℃, when it is 380℃, decomposition rate reaches the maximum, which is decomposition completely at 420℃; emulsion easier to get to different Tg styrene-acrylic emulsion, using latex emulsion blend technology has intrinsic properties of the resulting core-shell polymerization technique is close.3) We study "Amplification" of Process and formulation of latex obtained, and examined by the authority of its performance, the results show that the minimum film-forming temperature of the emulsion 0℃, rotational viscosity of 35 mpa.s, calciumion stability, are qualified mechanical stability, adhesion to 0, not detected VOC and heavy metalions, latex has better performance reproducibility can be used for industrial production.4) The micro-crosslinked emulsion intrinsic properties and mechanical properties of the coating results show: with the increase of the content of the functional monomer, the emulsion gel initially decreased after increasing, gradually increasing the rotational viscosity of the emulsion, the minimum film forming temperature increase the drying time becomes shorter, the better emulsion stability, increase gloss, hardness and adhesion improved tensile strength and elongation at break increased heat temperature.5) Modified Silica dioxide substitution studies have shown that in the case of formula determined, R-type and J-type silica powder substitute optimum amount of titanium dioxide 25.00wt%, better stability of latex paint, micro-silica can be added to improve the hardness of the coating, reduce the gloss of the coating, does not appear floating color, blur phenomenon; coating film by use of a cross-sectional SEM analysis, studies have shown that micro-silica enriched in the film forming process will occur to the coating film surface, the uneven surface of the coating layer structure formation; use titanium dioxide partial replacement of titanium dioxide, can not only improve the hardness of the coating, but also reduce production costs. We can get NO-VOC Latex coating successfully.