6 self factors influencing the gloss of water-base

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Six self factors affecting the gloss of water-based glazing oil

in the packaging and printing industry, sometimes water-based glazing oil is used. Today, China paper will take you to know about a water-based glazing oil and introduce its function in detail

water based polishing oil is a green and environment-friendly product. Its solvents are mainly water and some alcohols, and its volatiles will not pollute the environment. In recent years, water-based glazing oil has been gradually developed with the increasing voice of people for environmental protection. At present, its technology is not mature enough. The main problems are that the surface finishing effect is poor, and the gloss can not achieve the desired effect

the coating process of varnish is essentially the process of leveling and drying the varnish on the printed matter. There are many factors that affect the gloss of water-based glazing oil, such as the appearance quality of the coated material, the coating process, equipment and the quality of the glazing oil itself. Here we mainly discuss the influence of the performance of water-based glazing oil on the gloss

the factors that affect the gloss of water-based varnish include the selection of polymer monomer for resin, the proportion of water-soluble resin and lotion, the leveling property, viscosity, pH value and surface tension of varnish. How can we check whether the tensile tester is qualified after purchasing a tensile tester? Etc

1. The influence of polymer monomer on the gloss of water-based varnish

the different properties of polymer monomer have a very important impact on the gloss and other properties of the prepared water-based varnish. Therefore, the selection of appropriate polymer monomer is the most important step to improve the gloss of water-based varnish. In practical use, a variety of monomers are usually used for copolymerization. When selecting monomers, it is necessary to not only add a large number of additives with improved gloss, but also improve the use of monomers with other properties of glazing oil. In general, they can choose monomer copolymerization from table 1

the possible monomers used in the acrylic resin of water-based varnish are: methyl methacrylate, styrene, methyl acrylate, acrylic acid- β- Hydroxypropyl ester, acrylic acid, etc. By increasing the amount of methyl methacrylate and styrene, the coating has high hardness, good gloss, but it is brittle, with poor folding resistance and solubility resistance. Therefore, in order to obtain high gloss water-based varnish, appropriate polymer monomers must be selected

2. Mixing ratio of water-soluble resin and lotion

as mentioned earlier, the mixing ratio of water-soluble resin and lotion has a great impact on the gloss of water-based glazing oil. Increasing the amount of lotion can improve its gloss, but reduce its leveling and processability; Increasing the amount of water-soluble resin can improve the leveling and processability of the varnish, but its gloss will be reduced. During preparation, refer to the proportion in the previous formula

3. The effect of leveling on the gloss of water-based varnish

the leveling of water-based varnish is another important factor affecting its gloss, which is affected by the viscosity, pH value and surface tension of the varnish

if the varnish has good leveling property, it can quickly level before the coating is dried to form a smooth surface, and the coating will have high gloss; If the glazing oil cannot be dried before leveling, it will leave some streaks, sand holes, etc., which will reduce its gloss

the key factors affecting the leveling performance are the leveling viscosity and drying speed of the varnish in the leveling process. If the leveling viscosity can be kept low and there is a small change rate in the initial stage, the coating can be leveled quickly. Leveling viscosity is related to the viscosity, pH value, thixotropy of the water-based varnish and the absorption rate of the coating, Ganfeng lithium announced. The drying speed also affects the leveling property. If the speed is small, the change rate of leveling viscosity is small, and the leveling time is large, so it can be fully leveled

4. Viscosity must be easy for the gloss of water-based glazing oil; The viscosity of water-based glazing oil has a very important impact on the leveling, wettability and other coating suitability in the coating process. This is because the surface of the printed matter has certain absorption to the varnish, and the absorption rate of the surface of the printed matter to the varnish is directly proportional to the viscosity of the varnish. If the viscosity value of the polishing oil is too small, the viscosity of the polishing oil will change too much during the leveling process when the paper with high absorption rate is coated. In the initial stage, the viscosity can still meet the leveling requirements, but in the later stage, the viscosity of the polishing oil increases significantly, so it is difficult to meet the leveling requirements again. As a result, the leveling ends prematurely, causing uneven coating on the surface of the printed matter, Some parts lack polish, which affects the smoothness and gloss of the film after drying and calendering

if the viscosity of the printed matter with low absorption is too low, sagging will occur, resulting in uneven coating and poor drying. If the viscosity is too high and cannot meet the requirements of leveling, the leveling will end prematurely and the gloss will become worse

5. Effect of pH value on gloss of water-based varnish

the pH value of water-based varnish is mainly adjusted by ammonia. Generally, the pH value of water-based varnish should be controlled between 8 and 9. If the pH value is too high and the alkalinity is too strong, the viscosity of the varnish will decrease, affecting the gloss, slowing down the drying speed and deteriorating the water resistance; When the pH value is too low, the alkalinity is too weak, the viscosity increases, and the ammonia water volatilizes too quickly in the leveling process, so that the leveling ends too quickly and affects the gloss

6. Effect of surface tension on water-based glazing oil

the surface tension of glazing oil is not only an important factor affecting gloss, but also an important factor affecting the overall quality of glazing oil. In order to meet the experimental requirements of hot rolling, castings and forgings, coating varnish is usually realized on the spot or on the ink film, and their surface free energy is usually small. The surface tension value of the varnish has a great difference on the wetting, adhesion and penetration of the same print, and the film-forming effect after coating and calendering is also very different. If the surface tension value of the polish is very small, the polish is easy to wet the surface of the printed matter, and it is easy to flow into a smooth and uniform film surface under the action of the surface tension; If the surface tension value of the varnish is large, it is difficult to wet the ink film on the surface of the print, and it is not easy to form a uniform coating layer; When the value is greater than the surface tension of the ink film of the printed matter, the coated varnish coating will shrink to a certain extent, and even sand holes will appear in some parts

the above are the main factors affecting the gloss of water-based varnish. In addition, the solid content of water-based varnish also affects its gloss. The effect of solid content on gloss is similar to that of viscosity. Generally, the solid content of water-based polishing oil shall be controlled within 30% ~ 40%

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