Low Gloss in Water-Based Varnish? 6 Formulation Factors You Should Optimize
Water-based varnishes are classified as eco-friendly products; the primary solvents used in their formulation are water and various alcohols, ensuring that their volatile components do not pollute the environment. The development of water-based varnishes has gained momentum in recent years, driven by the growing public demand for environmental protection. The process of applying varnish essentially involves the coating material leveling out and drying on the printed substrate. Numerous factors influence the gloss level of water-based varnishes—including the surface quality of the substrate, the coating process itself, the equipment utilized, and the quality of the varnish formulation. This discussion focuses primarily on how the intrinsic properties of the water-based varnish affect its gloss. Factors inherent to the varnish that influence its gloss include the selection of polymer monomers for the resin, the blending ratio of water-soluble resins to emulsions, as well as the varnish's leveling properties, viscosity, pH value, and surface tension. 01 The Impact of Polymer Monomers on Water-Based Varnish Gloss The distinct properties of the polymer monomers used have a profound impact on both the gloss and other performance characteristics of the resulting water-based varnish. Consequently, selecting the appropriate polymer monomers constitutes the most critical step in enhancing the gloss of water-based varnishes. In practical applications, it is common practice to employ a copolymerization process involving multiple monomers. When selecting monomers, it is essential to incorporate a substantial proportion of monomers known to boost gloss, while simultaneously ensuring the inclusion of monomers that serve to improve other key performance attributes of the varnish. Monomers commonly utilized in the acrylic resin formulations for water-based varnishes include methyl methacrylate, styrene, methyl acrylate, β-hydroxypropyl acrylate, and acrylic acid. Increasing the proportion of methyl methacrylate and styrene results in a coating with high hardness and excellent gloss; however, such coatings tend to be more brittle and exhibit reduced resistance to folding and solvents. Therefore, to achieve a high-gloss water-based varnish, the selection of appropriate polymer monomers is absolutely essential. 02 The Blending Ratio of Water-Soluble Resins to Emulsions As previously noted, the specific ratio at which water-soluble resins are blended with emulsions exerts a significant influence on the gloss level of the water-based varnish. Increasing the proportion of emulsion can enhance glossiness, but it simultaneously diminishes the varnish's leveling properties and processing suitability. Conversely, increasing the proportion of water-soluble resin improves the varnish's leveling properties and processing suitability, yet results in a reduction in glossiness. During preparation, one may refer to the proportions specified in the preceding formulations. 03 The I...
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