Water-based ink gravure plastic film printing and paper printing case analysis
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Water-based ink gravure plastic film printing and paper printing, the case analysis is as follows.
Water-based ink gravure plastic film printing case one
Gravure printing machine, electro-engraving plate, plate depth 45 microns, printing speed 40 m / min, drying temperature 60-70 ° C, printing materials: BOPP film, BOPP matte film and low-pressure HDPE film, ink variety: WE-0824 in yellow ink .
Water-based ink gravure plastic film printing case two
Gravure printing machine, electro-engraving plate, plate depth 45 microns, printing speed 60 m / min, drying temperature 60-65 ° C, printing material: BOPP film, post-printing film. Ink type: yellow ink in WE-0824.
Water-based ink gravure paper printing case three
Gravure printing machine, electro-engraving plate, plate depth 45 microns, printing speed 80 m / min, drying temperature 60-65 ° C, printing materials: ordinary white paper, ink varieties: WZ-0824 yellow ink.
Printing speed: In the first, second and third printing cases, the printing speed is 40 m / min 60 m / min 80 m / min, water-based ink gravure plastic film printing can be printed without changing the board. If the printing is changed to lighter, the printing plate can be increased to a depth of 15-25 microns, and the printing speed can be increased to 100 m/min or higher.
The drying temperature is preferably 50-60 ° C, and the air volume is large, so that the ink transferred to the film is quickly dried.
In the second case of water-based ink gravure plastic film printing, due to the good drying and ventilation conditions of the gravure printing machine, the printing speed is 20 m/min faster than the printing case.
P H value: Before the water-based ink leaves the factory, the PH value is controlled at 8-9, and generally no adjustment is needed.
Ink Viscosity: The accuracy and consistency of ink viscosity during gravure printing is key. If the viscosity is too high, the transfer performance of the ink will be poor, which may cause defects such as dirty plates and pastes. If the viscosity is too low, it will cause light color, dot enlargement, and uneven ink transfer. The water-based ink has been tested for viscosity before leaving the factory. Check the viscosity of -3 at 15 -25 sec / 25 °C. The viscosity can also be adjusted with pure water during use.
Adhesion fastness: BOPP film commonly used in printing is a non-polar polymer, which must be surface treated before printing. In the first and second cases, the thin touch used was a BOPP film, a BOPP matte film and a low-pressure HDPE film with a surface tension of 38 dyne/cm after corona treatment, and the adhesion fastness after printing was excellent. Compared with similar products at home and abroad, the adhesion fastness of WE type plastic film gravure aqueous ink printing is the best and leading.
Gloss: The gloss of the water-based ink gravure plastic film printing and the printing of the paper product to achieve and exceed the gloss of the solvent-based printing product, which was well received in the three cases.
Peel strength: In the case of water-based ink gravure plastic film printing case 2, the BOPP film after lamination was tested: longitudinal peel strength 1N/15mm, transverse peel strength 0.89N/15mm. Generally, the peeling strength of the chloropropene type ink printing product is 1.5-2.5N/15mm, and the peeling strength of the benzene solvent type ink printing product is greater than the peeling strength of the chloropropyl type ink printing product and the peeling strength of the aqueous ink printing product. In the second case, the solvent-based polyurethane laminating adhesive is used, which has low bonding strength with the aqueous ink. Therefore, the plastic film gravure aqueous ink should be combined with the corresponding aqueous laminating adhesive film to meet the requirements of peel strength. Accepted by the market.
Printing: After the ink is poured into the ink tank, let the printing plate idling for 2-3 minutes, which will wet the printing plate and stir. When the printing process is temporarily stopped when observing the printing, the printing plate should not be stopped to avoid the printing plate. The ink is dried to cause a plate, because the aqueous ink is not resolubilized. In the printing case one, the version was used, and it was wetted and washed with a special washing solution. After adjusting the viscosity of the ink according to the depth of the plate, just add a new ink to ensure that the color and color density of the print are consistent. Immediately after printing, the plate should be cleaned, the remaining ink is installed, the water is placed in the tank, and the plate is rotated for cleaning or 3% washing powder solution is used for cleaning. It is important to note that the original printer, ink tank, and scraper using solvent-based inks must be cleaned. The temperature of the printing workshop should be controlled between 18 °C and 28 °C, and the humidity in the printing workshop 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 printing: Water-based inks have been widely used in the printing of papers such as wrapping paper and paper boxes, which are due to the fact that paper products are evaporatively dried and absorbed dry. Water-based ink paper printing is mainly used in flexographic printing. Water-based ink gravure paper printing began with the printing of cigarette labels, and some ink inks affected the promotion and use due to the lack of performance. WZ type paper gravure water-based ink is successfully printed in the printing case 3 because of its high gloss, resistance, good abrasion resistance, good water resistance, low viscosity and good printing adaptability. If it can be used in the light version, the plate is electro-engraved or Laser engraving, the depth should be between 15-25 microns, the effect will be better. The factory has tried many times of domestic and international ink printing, which is not ideal. This is because the universal carton ink is not suitable for gravure paper printing, and the traditional flexographic printing ink cannot fully meet the needs of gravure paper printing.
WE type plastic film gravure water-based ink product technical indicators are as follows:
Color (scratch method): approximate standard
Tinting strength (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
Initial dryness (scraper fineness method, 25 °C): 10 to 20 mm
Adhesion fastness (after 24 hours of scraping): fastness - 100% no shedding; peel fastness - 100% no shedding;
Resistance to 1:1 water alcohol performance (soaking for 2 hours): The ink film does not fall off
Alkali resistance (soaked in 1% NaOH solution for 2 hours): the ink film does not fall off
The cost of water-based plastic gravure ink is calculated: the price of chloropropane solvent-based gravure ink is about 20 yuan/kg, the price of alcohol-soluble gravure ink is about 40 yuan/kg, and the price of water-based gravure ink is 40 yuan/kg. Since the ink printing plate is shallow, the printing plate has a depth of 15-25 micrometers, and the ink consumption per square meter of the ink is 50-60% of the solvent-based ink, and the color density thereof is high. Therefore, the printing cost of the water-based gravure ink is slightly higher than that of the solvent-based ink, and lower than that of the alcohol-soluble ink.
Through the three cases of water-based ink gravure plastic film printing and paper printing, the color printing and packaging factory's selection and requirements for gravure water-based inks are known: water-based inks have good cost performance, high color density, stable hue, high gloss, low viscosity, and strong adhesion. The degree is high, the drying is fast, and it can adapt to the needs of low, medium and high speed printing. The color printing and packaging factory agrees with the gravure water-based ink printing and accepts it.
. The industry's mandatory standard data is: organic volatiles voc, that is, the total residual solvent is less than 10 mg / square meter, the total residual amount of benzene solvent is less than 3 mg / square meter, as well as heavy metal content requirements, smell requirements. The General Administration of Quality Supervision, Inspection and Quarantine has launched the food packaging container market access system - QS certification. Water-based inks are the first choice for color printing and packaging factories. Of course, the application of water-based gravure ink to plastic film printing is still in its infancy, and the printing of water-based ink gravure paper needs to be improved.