What are the factors affecting the gloss of water-based varnish?
Release Time：
2023-06-19
Source：
The polymers selected in the film-forming resin in the formulation of water-based varnish have an important influence on the gloss of the finished product. In actual production, methyl methacrylate, butadiene, methyl acrylate, methyl acrylate, acrylic acid-β-hydroxyacrylic acid, acrylic acid, etc. Increase the amount of methyl methacrylate and butadiene, the coating hardness, good gloss, but brittle, folding resistance, poor resistance to dissolution.
Second, the ratio of water-soluble resin and emulsion in the formulation of varnish.
Increase the amount of emulsion in the formula can improve its gloss, but will reduce the leveling and processing suitability of light oil; increase the amount of water-soluble resin can improve the leveling and production suitability of light oil, but the gloss will be reduced.
Third, the impact of leveling on the gloss of water-based varnish.
Leveling is the key factor to determine the gloss of water-based varnish, leveling is influenced by the viscosity of the commodity, pH and interfacial tension. Selecting the right leveling agent in the formulation can effectively improve its construction flatness. If the varnish has strong leveling, the coating can be quickly leveled before drying, the surface is smooth and the coating is high gloss; if the varnish is not dried before leveling, it will leave some traces, sand holes, etc. and reduce the gloss.
Fourth, the impact of PH value on gloss.
General water-based varnish pH value should be maintained between 8-9, pH ammonia is usually used to adjust the value. pH if the value is too high, the viscosity of the varnish will drop, affecting the gloss, slowing down the drying speed, reducing water resistance; pH if the value is too low, the viscosity will rise, ammonia volatilizes relatively too fast in the leveling process, so that the leveling process ends too quickly, affecting the gloss of the final film.
Five, viscosity, finished solid content on the impact of gloss.
Finished product viscosity has an important impact on the leveling and humidity of the coating process. The surface of the print has a certain absorption to the varnish, and the absorption rate of the print surface to the varnish is proportional to the viscosity value of the varnish. If the viscosity value of the varnish is too small, when applied on the paper with high absorption rate, it will lead to excessive changes in the viscosity of the varnish during the leveling process, resulting in the premature end of the leveling, resulting in uneven coating on the surface of the print, part of the local under varnish, affecting the smoothness and gloss of the film after drying and polishing; if applied on the print with low absorption rate, the construction viscosity is too low flow hanging, resulting in uneven coating, poor drying and other problems.
Generally speaking, the solid content of water should be maintained at about 30-40%. The solid content of water-based varnish has a significant impact on its gloss, solid content on the film after the impact of gloss and viscosity is similar.
Sixth, the finished product interface tension on the impact of water-based varnish.
The interface tension of the varnish not only affects the gloss, but also is an important factor affecting the overall quality of the varnish. The size of the interface tension of the varnish and the same print soaking, adhesion and soaking effect is very different, coating and coating after the film effect is also very different.
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2023-06-19
2023-06-06
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