Advantages of water-based coating thickeners
1, Provides thixotropic thickening and regulates paint flow
2, Prevents paint film sagging and builds up thick layers of paint
3, Prevents paint splattering during coating (roll-on)
4, Prevents pigment deposition by creating a suspension effect
5, Improves liquid stratification for uniform paint appearance
Due to the introduction of bases, the gloss rises faster and the gloss is high. The gloss varies with the type of amine. Paints formulated with strong alkaline HEE I modified alkyd resins have the highest gloss. Even if the modified alkali is the same, the gloss will increase as the alkali content increases. The unmodified acidic alkyd paint has the lowest gloss.
The yield value of an acidic alkyd resin coating without modification increases synthetic amide wax as the gloss value decreases. However, the yield value of alkaline alkyd resin coatings modified with amines remained largely unchanged. The general pigment dispersion is prone to flocculation, and the structural viscosity of the dispersion increases. If the resin or the added dispersant can be adsorbed on the surface of the pigment to form an adsorption layer of a certain thickness, the pigment particles will not flocculate, and the structure formed in the dispersion system will have low viscosity and low yield value.
Disperse acidic carbon black in amine-modified and cold-mixed alkyd resin to make coatings. Due to the action of amine, the dispersion speed is accelerated and the gloss is high. However, the gloss of cold-stamping is lower than the gloss modified with the same amount of amine, and the yield value is roughly the same. Cold-mixable alkyd resin coatings have poor storage stability. After storage at 40°C for 4 days, the gloss is significantly reduced and the yield value is significantly increased. See Table 24 for details.
Table 2-4 Storage stability of amine modified and cold blended alkyd resin coatings
Through this test, it can be seen that the cold-mixed melamine alkyd resin has a wetting and dispersing effect on acid pigments, but the dispersion stability is poor, the gloss is greatly reduced after storage, and the yield value is greatly increased. The reason is that the molecular weight of the melamine resin is relatively low, the adsorption layer is thin, and a good steric hindrance effect cannot be formed. But it has a good wetting effect, and the gloss before storage is relatively high.
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