Water-based ink gravure plastic film printing and paper product printing case analysis

Beijing Incofan Chemicals Co., Ltd. conducted water-based ink gravure plastic film printing and paper printing at a color printing and packing plant in Xiong County, Hebei Province in March and April 2007. Case studies are as follows.

Water-based ink gravure plastic film printing case

Gravure printing machine, engraving, version depth 45 microns, printing speed 40 meters/minute, drying temperature 60-70 DEG C, printing materials: BOPP film, BOPP matt film and low pressure HDPE film, Ink type: WE-0824 yellow ink .

Water-based ink gravure plastic film printing case two

Gravure printing machine, engraving, version depth 45 microns, printing speed 60 meters / min, drying temperature 60-65 °C, printing materials: BOPP film, printed after the film. Ink varieties: WE-0824 yellow ink.

Water-based ink gravure paper product printing case three

Gravure printing machine, engraving, version depth 45 microns, printing speed 80 meters / min, drying temperature 60-65 °C, printing materials: ordinary white paper, ink varieties: WZ-0824 yellow ink.

Printing speed: In this printing case one, two and three, the printing speed is 40 meters/minute and 60 meters/minute and 80 meters/minute. The water-based ink gravure plastic film printing can be printed without changing the board. For example, if the printing is changed to shallow printing, the depth of the printing plate is 15-25 μm, and the printing speed can be increased to 100 m/min or more.

Drying temperature: 50-60 °C is appropriate, and the air volume should be large, so that the ink transferred to the film quickly dried.

Water-based ink gravure plastic film printing case II, due to the good condition of its gravure printing machine drying ventilation, than the printing case one, the printing speed is 20 meters/minute.

PH value: Before the water-based ink is shipped from the factory, the PH value is controlled at 8-9. Generally, no adjustment is needed.

Ink Viscosity: The accuracy and consistency of ink viscosity during gravure printing is the key. 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. If the viscosity is too low, the color will be light, the dots will be enlarged, and the ink will not be uniform. Water-based inks have viscosity control prior to leaving the factory, and the Cha-3 viscosity is 15 -25 seconds/25°C. Can also be used to adjust the viscosity of pure water
Adhesion fastness: BOPP film is commonly used in printing is a non-polar polymer, surface treatment must be carried out before printing. In the first and second cases, the thin film used was a corona-treated BOPP film with a surface tension of 38 dyne/cm, a BOPP matt film, and a low-pressure HDPE film. The post-print adhesion was excellent. Compared with similar products at home and abroad, the adhesion fastness of WE type plastic film gravure water ink printing products is the best and leading.

Gloss: Water-based ink gravure Plastic film printing and paper product printing gloss to achieve and exceed the gloss of solvent-based prints, in the three cases were unanimously praised.

Peel strength: water-based ink gravure plastic film printing Case II, after the film BOPP film, after testing: longitudinal peel strength 1N/15mm, transverse peel strength 0.89N/15mm. The peeling strength of general chlorinated and acrylic inks is 1.5-2.5N/15mm. The peeling strength of benzene-based solvent inks is greater than that of chlorinated polypropylene inks and the peeling strength of water-based inks. Case II uses a solvent-based polyurethane laminating adhesive, which has low adhesion strength to water-based inks. Therefore, plastic film gravure water-based inks must be matched with water-based laminating adhesive lamination in order to achieve peel strength requirements. Accepted by the market.

Printing: After the ink is poured into the ink tank, the printing plate idles for 2-3 minutes to wet the printing plate and the stirring effect. 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 being rotated. The ink is solid and causes a plug plate because the aqueous ink is not resoluble. The printing case has been tampered with and has been printed with a special printing solution that has been moistened and cleaned. According to the version of the dark and light before printing to adjust the viscosity of the ink, as long as the new ink can be added to ensure consistent color and color density before and after printing. After the printing is completed, the plate should be cleaned immediately, the remaining ink should be installed, the clean water should be placed in the tank, and the printing plate should be rotated for washing or transferred to a 3% detergent solution for cleaning. Special attention is paid to the fact that the printers, ink tanks, and squeegees that originally used solvent inks must be cleaned. The temperature in the printing shop should be controlled between 18°C ​​and 28°C, and the humidity in the printing shop should be controlled between 55% and 75%. In the printing case, only the plastic film printing case 2 meets the temperature and humidity requirements.

Water-based ink gravure paper product printing: Water-based ink has been widely used in the printing of packaging paper, paper box and other paper products, which is due to the better evaporation and drying of the paper products and absorption and drying. Water-based ink paper printing is mainly used in flexo printing. The printing of water-based ink gravure paper products began with the printing of smoke labels, and some inks affected their promotion due to their unsatisfactory performance. WZ type paper concave water-based ink has been successfully printed in printing case 3 because of its high gloss, resistance, good abrasion, good water resistance, low viscosity, and good printing adaptability. Laser engraving, version depth should be between 15-25 microns for ease, the effect will be better. The factory has repeatedly tried both domestic and foreign ink and wash printing, and it is not ideal. This is because universal carton inks are not suitable for gravure paper products, and traditional flexographic inks cannot fully meet the needs of intaglio paper products.

WE-type plastic film gravure water-based ink product specifications are as follows:
Color (scraping method): Approximate standard coloring force (scraping method): 95-105 % of the standard sample
Chromaticity (scraper fineness method): <10 micron
PH value: 8.0~9.0
Viscosity (check - 3 cups, 25 °C): 20 seconds at the beginning of the dry (scrape fineness meter, 25 °C): 10 to 20 mm attachment fastness (after scratching 24 hours): rubbing fastness - 100% no Shedding; peeling fastness - 100% without shedding;
Resistant to 1:1 hydroalcoholic properties (soaking for 2 hours): No ink film falling off Alkaline resistance (2 hours in 1% NaOH solution): No ink film falling off
Water-based plastic gravure ink use cost estimates: chlorinated and acrylic solvent-based gravure printing ink is priced at RMB 20/kg, alcohol-soluble gravure printing ink is priced at RMB 40/kg, and water-based gravure printing ink is priced at RMB 40/kg. Due to the shallowness of the ink-printing plate, the printing plate depth is 15-25 microns. The consumption of ink per square meter is 50-60% of the solvent-based ink, and its color concentration is high. Therefore, the use of water-based gravure ink printing costs slightly higher than the solvent-based ink, and alcohol-soluble ink.

Through water-based ink gravure plastic film printing and paper product printing, we learned that the color printing packaging plant's selection and requirements for gravure water-based inks: Water-based inks are better in terms of cost-effectiveness, higher color concentration, stable hue, high gloss, low viscosity, and good adhesion. The degree is higher, drying is faster, and it can adapt to the needs of low, medium, and high speed printing. Color printing and packaging factory is in favor of gravure water-based ink printing.

Water-based inks are the only non-toxic inks approved by the U.S. Food and Drug Association. The industry's mandatory standard data is: Organic volatile matter (VOC) is the total amount of solvent residue less than 10 mg/m2, total benzene solvent residue is less than 3 mg/m2, and heavy metal content requirements and odor requirements. The AQSIQ has started the food packaging container market access system - QS certification. Water-based ink is the first choice for color printing and packaging plants. Of course, the use of water-based gravure inks for plastic film printing is still in its infancy. Water-based ink gravure paper products still need to be improved.

In the three cases of water-based ink gravure plastic film printing and paper printing, the author deeply feels the pollution and poisoning of the traditional gravure printing on the production environment and the surrounding environment, and the impatientness of the printing workers. What is the reason why the Huns remain untouched? We are willing to work together with my colleagues in the packaging and printing industry to embrace the spring of environmental protection printing! Green seedlings are growing. Will the fall harvest be far behind?