Water Based Varnish for Paper

What problems should be paid attention to in the use of water-based varnish for paper?

1. Measurement of viscosity of aqueous varnish for paper. The measurement of viscosity is judged by the time when the liquid flows through the same quilt with holes at the lower part. Another common measurement method is to measure the resistance of the object moving inside the liquid. The viscosity of paper water-based varnish is determined by the former measurement method. The measuring instrument is a 4mm Diameter Measuring Cup according to din53211 standard. The viscosity of paper water-based varnish generally uses s (second) as the measurement unit. The viscosity of water-based varnish for domestic paper varies from 15s to 80s. The viscosity of the water-based varnish of the paper when the polishing machine is polishing should be maintained at 20-50 seconds, and the viscosity of the varnish used by the offset press should be maintained at 30-60s.

2. How to dilute water-based varnish for paper. If the purchased water-based varnish has high viscosity, it needs to be diluted. The solvent of water-based varnish for paper is water, so it can be diluted directly with water, but the amount of water should be controlled in the dilution process. Adding 1:1 ethanol to water can reduce the curing time, but it will affect the gloss. If you have to, it is recommended not to dilute by yourself, because there is no standard instrument to measure in the process of dilution with water, so it is easy to add too much water.

3. What should we pay attention to when drying after glazing.

(1) In the process of glazing operation, the drying condition should be checked at any time, especially in the case of substrate with poor absorption, glazing with large amount of ink or glazing coating. The inspection method is to take a wet / wet polishing sample from the paper receiving device in the printing equipment and observe the drying time of the polishing part printed with ink. Generally, 15-30 seconds is normal. If the drying time is long, it can be adjusted by spraying a small amount of powder.

(2) When polishing on both sides, the polishing oil with good wet sealing shall be selected, and the first polishing surface shall be completely dry. After polishing, a small amount of powder can be sprayed to promote drying.

(3) If you want to speed up drying and gloss, you can use infrared radiation, but there is also a risk of rubbing the back.

(4) Hot air drying is the most reliable drying method for water-based varnish of paper. Pay attention to vertical air supply during hot air drying and ensure effective exhaust conditions.

(5) The light film coated and dried by the machine will have a slight smell, which is harmless to human body. Therefore, users need not worry.

Characteristics of aqueous varnish for paper

1. Bright color, fine ink quality, high coloring power, strong fastness, complete color samples, non combustible, non explosive and non corrosive;

2. The ink viscosity changes stably, the printing dot is clear, not easy to decolorize, and the color intensity is high;

3. Low foaming, dry, with good water washability.

4. It has good wear resistance, strong water resistance and good frost resistance. It is very suitable for frozen packaging printing and different printing equipment.

Precautions for water-based varnish of paper:

1. In printing, pay attention to controlling the parameters of water-based ink, including ink viscosity, fluidity, thixotropy and plasticity.

2. Pay attention to the control index of water-based ink. The control indexes of water-based ink mainly include fineness, viscosity, pH value and drying speed, which play a decisive role in the application effect of ink.

3. Because the water-based ink is a pure water-based system, pay attention not to mix the water-based ink with alcohol based ink and solvent-based ink or add organic solvent to the ink to avoid printing quality problems.

The water-based varnish ink of paper is suitable for the printing of carton outer packaging. It has rich colors and various varieties. It has three categories: ordinary, middle-grade and high-grade ink. It is suitable for different types and requirements of equipment. It is widely used in corrugated cartons such as electronics, food and so on.

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