Lamination process of paper products (2)

How to Guarantee the Stability of Waterborne Varnish Polishing Quality

Of course, it is also necessary to conduct incoming inspection to ensure the stability of batch quality. The incoming inspection items are the same as solvent-based varnish, ie, viscosity, solids content, and pH. General waterborne varnish can be used directly on the machine, and the water's volatility is much weaker than the day's water, so the waterborne varnish is of relatively stable quality. However, if the circulation is repeated for a long period of time, especially during the high-temperature drying season, the water in the water oil will evaporate a lot. Therefore, the amount of water added can also be determined by measuring the viscosity. In addition, the operator must adjust the speed, roller distance, and baking tunnel temperature in accordance with different conditions. This is also an important link to ensure the quality of the waterborne coating.


How to ensure the stability of the polishing quality When polishing, please note the following points:

1. Polishing temperature is moderate, the temperature is too high and it is difficult to remove the plate and damage the oil film. If it is too low, the printing product cannot adhere to the steel belt and the polishing effect is not good.

2. Grinding pressure should be appropriate, according to the thickness of the board, polishing effect to adjust the pressure. The general pressure should be maintained at about 200-250kg/cm2.

3. In order to obtain a good mirror effect, the oil layer should not be too thin when glazing, and the glazing effect is best after about half an hour of polishing.

4. To ensure the stability of the polishing quality, there are two things that must be done: one is to avoid pauses in the middle and the other is to keep the polishing speed stable. Table 1. Causes of Solvent-based and Waterborne Coatings Common Causes and Improvements Countermeasures Common Causes Analysis of Causes of Improvement Solutions After Coating, the surface adhesion to varnish is too high. Add appropriate amount of water to dilute the product. Waterborne varnish should be diluted with alcohol or water. Too thick to adjust the gap between the coating roller and the pressure roller, or add a small amount of solvent to dilute the glazing equipment. Hot air drying equipment. Aging replacement drying equipment. Varnish itself is poor in dryness. Change with a faster drying speed. Vareasing speed is too fast to slow down After the speed of the machine, the wear resistance is poor, the surface is easy to change color, the wear resistance of the varnish is poor, and the wear resistance of the varnish is too low. The ratio of the solvent is properly reduced when the varnish is opened. The varnish layer is too thin to increase the coating roller. The gap between the pressure roller and the ink is not dried until the ink is dry and the glazing is applied. The adhesion of the oil film is poor, and the ink is not dried easily. The ink is not dried until the ink is dry and then the ink absorption of the glazing printing paper is too poor. Better quality of paper Varnish is not good Replace with new varnish Drying temperature is too high Properly lower drying temperature Gloss difference Oil layer is too thin Thickness of coating should be increased, or a layer of base oil, then varnish, or High gloss oil concentration Varnish is too thin should be reduced to reduce the proportion of days that water Low calendering temperature Guaranteed temperature at 85-105 °C Oil tank mixed with other types of varnish to thoroughly clean the oil tank Printing ink and varnish are not suitable for use The new ink or varnish belt steel belt atomizes the steel belt to replace the new printing paper. The absorption of paper is strong, the absorption of the varnish is too large, and the paper with poor absorption is poor in smoothness, and the surface is smooth. A better degree of gloss of paper varnish itself is poor. Replace the varnish. Polish the surface. There are pits on the surface. The oil thickness is too thin. The thickness of the oil layer should be appropriately increased, or the varnish concentration must be increased. The paper drying time is not enough. The proportion of wear-resistant additives in the gloss oil is too high for about one hour. Replace with a new Varnish Polished when off the plate Grinding temperature is too high Reduce the polishing temperature, generally does not exceed 105 °C Polishing pressure is too high to reduce the pressure of the oil is not dry properly after a period of time and then polished (secondary Title) VU coating process The UV coating process is a process in which a layer of UV varnish is applied to the surface of the print and the varnish is cross-linked, conjunctated, and cured by irradiation of ultraviolet rays (UV rays). UV Varnish is made by photopolymerization, diluting monomers, photoinitiators and additives through polymerization reaction. Has fast drying (drying time only 0.5-3S), corrosion resistance, solvent resistance, high gloss, wear resistance, environmental protection and other advantages. (Tier 3 of the title) UV light (ultraviolet rays) UV light is a radiation other than purple visible light and has higher energy (see Figure 4 for details).

UV Varnish Curing Mechanism The photoinitiator excites free radicals under the action of ultraviolet light, transfers the energy to the double bond-rich copolymer and dilutes the monomer to generate a chain reaction, and instantaneously produces a crosslinked and cured film. (Tier 3) How to Guarantee the Stability of UV Polishing Quality

1. Inspect the UV oil to ensure that each batch is qualified. Test items include viscosity and solids content.

2. Do not use slow-drying inks. There may be quality problems when using gold-silver inks. When using these inks, the gloss and adhesion should be measured after polishing.

3. Do not use leveling additives with high surface activity. Do not use anti-scratch additives as much as possible, and do not use too much dust.

4. Paper/plates used for polishing paper should have low permeability. After the printing ink, the print should be allowed to air for more than 12 hours and then UV glazing.

5. Avoid mixing water into UV oil when washing.

6. The speed of UV coating should not be too fast. The UV lamp should have enough light intensity to ensure that the light oil is completely cured.

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