WE-type plastic film gravure ink characteristics

1 Comparison of three plastic film gravure inks

1) Solvent type plastic film gravure printing ink

At present, the domestic plastic gravure inks are mainly solvent-based inks, mainly chlorinated polypropylene inks. With toluene and other solvents, it accounts for almost 50% of gravure ink components. High volatile solvents contain aromatic hydrocarbons, which are toxic and flammable. Excessive benzene poses a great harm to the human body, and the gravure printing speed is high. Therefore, it is necessary to use volatile ink to meet the printing requirements, which makes the gravure printing problem particularly prominent in all printing processes.

2) alcohol-soluble plastic film gravure ink alcohol-soluble plastic gravure ink has low odor, benzene, etc., can effectively reduce the impact of residual solvents on the quality of packaged food, is now gradually promoted, but with the gravure With the performance and quality of printed products still need to be improved.

3) Water-based plastic film gravure ink

Water-based gravure inks for plastic films have only just begun to be used. It is an environmentally friendly liquid ink made from water. It has the characteristics of non-flammable, non-explosive, non-toxic, non-irritating, stable ink, bright color, high gloss, non-corrosive printing plate, easy operation, low printing cost, good post-print adhesion, strong water resistance, and rapid drying. The products printed with water-based inks are completely non-toxic and environmental friendly in the production environment. The biggest feature is that they reduce the emission of organic volatiles (VOCs) into the atmosphere. Water-based inks are currently non-toxic inks approved by the U.S. Food and Drug Association in a variety of inks.

Water-based inks, because they do not contain volatile organic solvents, improve the working environment, completely eliminate the toxic and harmful substances in solvent-based inks, and eliminate the contamination of packaged goods. It is mainly used for corona-treated PE, PP, PE 17, PVC films, printed food bags, milk packaging bags, pharmaceutical packaging bags, candy bags, beverage bags, toy packaging bags and other packaging and printing products. Adapt to print speed 20-1OOm /rain.

Ink ink applications are mainly based on flexographic printing and gravure printing. The inks widely used in foreign countries have good environmental protection and good ink performance. They are mainly characterized by: stable ink, high brightness, strong coloring power, high adhesion fastness, and drying speed that can meet the needs of printing speed. Four-color overprinting and spot colors Printing can be. Water-based gravure ink has been widely used in the printing of papers such as packaging papers, paper boxes, etc. This is due to the better evaporation and drying of the paper products and absorption and drying. The use of water-based inks in flexo printing is also rapidly progressing in China. The proportion of inks in flexo presses is increasing day by day. However, the use of water-based gravure inks for plastic film printing is still in its infancy. This is mainly due to the fact that water-based inks cannot completely achieve the performance of solvent-based inks in terms of adhesion, printing speed, and gloss in gravure printing. The WE-type gravure water-based ink has enabled new products in the field of plastic film gravure printing that can completely meet the required standards. The performance comparison of plastic film gravure water inks is shown in Table 1.

The conclusion after using the three types of water-based gravure inks in testing and production: The main drawback of No. 1 product is its poor adhesion, slow drying speed, and it can be used in production, but fundamental problems are not solved. The No. 2 product can be used on a gravure printing machine of 30 to 100 m/min, but there is a defect that the attaching fastness is slightly inferior. The B0PP thin film printed with WE-type water-based gravure ink was boiled for a minimum of boiling water (100°C) and then removed by drying. Put it into 40qC 30% hydrogen peroxide for 2 minutes, then remove it and dry it. The gloss is unchanged and the adhesiveness does not change. The proof of use in production and printing: The performance of WE-type water-based gravure ink has fully met the requirements of gravure printing machine production, and has reached the international advanced level of similar products in terms of attachment fastness, drying speed, color concentration and glossiness and other major performance indicators. .

2 WE type plastic gravure ink

Product technical specifications Color (scraper fineness method): <15 um; pH value: 8.0-9.0; viscosity (coating 4 cups, 25 °C) 20 ~ 50s; color (squeegee method): Approximate Standard sample; Coloring force (scraping method): 95-105% of the standard sample;

3 plastic film gravure water ink use matters needing attention

When used, the viscosity of the ink can be adjusted with water, and the viscosity of the coated 4 cups is controlled at 15 to 25 seconds/25°C. If the viscosity is too high, the transfer performance of the ink may be poor, and the defects such as a dirty plate and a paste plate may be easily caused. When the plastic film gravure water-based ink is used, the pH value should be controlled at 8.5 to 9. It should not be too large or too small. Plates are either electro-engraved or laser-engraved, and the plate depth should be between 15 and 25 um. The existing version is generally 35-55 um deep. The shallow version can increase printing speed and save ink. Excessive printing will affect the print speed, and it consumes a large amount of ink and is prone to blocking. The drying temperature of 50-60°C is suitable, and the air volume is large, so that the ink transferred to the film is rapidly dried. After the ink is poured into the ink tank before printing, allow the plate to idle for 2-3rain, wet the plate and agitate. If the printing process is temporarily stopped while observing the printing product, the printing plate must not be stopped to prevent the printing plate from rotating. The ink dry solid caused a plug version. Such as plug version can be wetted with a special cleaning solution. Before printing, adjust the viscosity of the ink according to the depth of the printing plate, and try not to add water to the ink during the printing process. Just add new ink to ensure consistent color and color density before and after printing. The plate should be cleaned immediately after printing and the remaining ink should be installed. Put fresh water into the tank, rotate the plate for cleaning or transfer the 3% detergent solution for cleaning.

Color printing and packaging plant selection and requirements for plastic film gravure water-based ink: water-based ink is better than the cost performance, high color, stable color. High gloss, fineness controlled below 15 um, viscosity (coated 4 cups) 15-25s, high adhesion strength, able to adapt to high speed printing needs, drying faster.

Waterborne plastic gravure ink cost estimate: Chloro-propylene solvent-based gravure ink price 20~30/yuan kilograms, alcohol-soluble gravure ink price 50 yuan/kilogram, water-based gravure ink price 40 to 45 yuan/ kilogram. Since the ink printing plate is shallow, the depth of the printing plate is 15-25 um, and the ink consumption of the ink per square meter is 50-60% of the solvent type ink, and the color concentration thereof is high. Therefore, the use of water-based gravure ink printing costs slightly higher than the solvent-based ink, but lower than the alcohol-soluble ink, its excellent cost performance is undoubtedly the best choice for color printing and packaging plants.