| This paper mainly studies the formula composition of the two-componentwaterborne polyurethane automotive topcoat and two kinds of automotive white andmetallic topcoat with excellent comprehensive performance have been prepared. Thewhole paper includes two parts as follow:In the first part, it is the formula composition of the varnish coat has been studied,and the two-component waterborne polyurethane automotive varnish coat withexcellent comprehensive performance has been prepared. Experiments have beendone to examine the influence of the choice of different hydroxyl emulsion as well ascuring agent, the mole ratio between n(-NCO) and n(-OH), the applicable period oftwo-component coating system, preparation technology and additives on the paint andcoating performance. The experimental results have showed that: It could be achievedto have one kind of film with excellent comprehensive performance prepared whenhydroxyl acrylic ester emulsion A was combined with isocyanate curing agent F, withn(-NCO)︰n(-OH)=1.5and spraying construction within3h after the coating has beenpreparaed well. Part A needs to add0.01%(percentage of total system) defoamingagent TG810to gain the best defoaming effect, part B can avoid bubbles throughmanually stirring, if make sure the mixed speed of part A and part B below and let themixture stay for30min, the bubble can be completely eliminated. Adding0.4%organic silicon flowing agent TG700and0.2%substrate wetting agent TG520,smooth without shrinkage film can be obtained. Using the baking condition offlowing10mins in room temperature and baking3h in80℃and baking24h in50℃and controlling the dry film thickness between30-50μm, it can be to obtained thevarnish coat with excellent performance but none bubble hole.In the second part, it is the formula composition of white and metallic base painthave been studied and two-component waterborne polyurethane automotive white andmetallic topcoat with excellent comprehensive performance have been prepared afterfinishing varnish. Experiments first have been done duing the preparation of whitebase paint to examine the effect of titanium dioxide, wetting dispersing agent, defoamer, flowing agent and construction viscosity on coating performance. Theexperimental results have showed that: Selecting the wetting agent CF-10anddispersant TG755with the dosage of1%and4%(percentage of titanium dioxideR902) as well as PVC of15%, the titanium pigment can get best dispersion effect tohave the best performance coating. Using the compound of defoaming agent X109and TG810with the dosage of0.025%/0.025%(percentage of total system) to get thebest defoaming effect. Through adding0.5%(percentage of total system) flowingagent TG700, smooth without shrinkage film can be obtained. Adjusting the paintviscosity to38″and controlling the wet coating thickness between65-100μm, thecoating performance is better without sagging. Secondly, the experiments examine theAluminum silver paste, wetting agent, solid content, orientatioal agent, anti-settingagent and thickening agent on the progerties of coating. The experimental results haveshowed that: Choosing aryl alkyl polyether type of wetting agent with dosage of0.3%(percentage of total system) and binder ratio of1︰10to obtained the better coating.When the solid content is35%and orientational agent with dosage of3%(percentageof total system), the coating can get the highest gloss and Aluminium powder hasgood directional arrangement. The coating can get good anti-setting and anti-delamination with0.16%(percentage of total system) of anti-setting agent BYK420.Choosing hydrophobic modified acrylic ester thickner and adding amount of5.0%(percentage of total system) to adjust the construction viscosity between30-35″(measured with4cups), it will be easyier to spraying atomization, and obtain coatingwith good flowing property and high gloss. |
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