Application of Water-based Ink in Plastic Film Gravure

At present, the domestic plastic gravure inks are mainly solvent-based inks, mainly chlorinated polypropylene inks. Toluene and other solvents account for almost 50% of gravure ink components. High volatile solvents contain aromatic hydrocarbons, which are toxic and flammable. The high speed of gravure printing requires the use of highly volatile inks to meet printing requirements, making gravure printing a particularly prominent environmental issue in all printing processes. Alcohol-soluble plastic gravure ink has low odor, benzene-free characteristics, which can effectively reduce the residual solvent on the quality of packaged food. Alcohol-soluble plastic gravure inks are gradually being promoted, but the compatibility with gravure printing machines and the quality of printed products still need to be improved. Water-based gravure inks for plastic films have only just begun to be used. Plastic film gravure water-based ink is an environment-friendly liquid ink made of water as a solvent. 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.

Plastic film gravure water ink printing

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 in rotogravure printing machine in PE, PP, PET, PVC and other film printed food bags, shopping bags, milk packaging bags, medicine packaging bags, sausage bags, candy bags, beverage bags, children Toy packaging bags and other packaging printing products. Adapt to print speed 20-100 meters / min.

According to relevant reports, the CNCA will implement food product packaging products such as food packaging bags and beverage packaging bags, and will enforce the product certification control system (ie, 3C certification) from 2006 onwards, and must achieve a comprehensive food packaging bag hygiene. standard. Only plastic food packaging products that meet the 3C standard can be listed. This is a great challenge and a great opportunity for more than 10,000 color printing and packaging companies and ink manufacturers across the country.

Ink ink applications are mainly based on flexographic printing and gravure printing. The inks widely used in foreign countries have good environmental protection performance and good ink performance. They are mainly characterized by: stable ink, high brightness, strong coloring power, high attachment fastness, and drying speed that can meet the needs of printing speed. Four-color overprinting and spot colors Printing can be. Water-based gravure printing inks have been widely used in the printing of papers such as packaging papers, cardboards, and paper boxes. This is due to the fact that the paper products are evaporatively dry and absorb dry. Water-based inks are used in flexo printing and are currently developing rapidly in China. More than a dozen ink factories have developed flexographic inks. The proportion of ink in the flexo press has increased. 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 gravure printing because of their adhesion, printing speed, and gloss. 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.

Let's take a look at the performance comparison chart of plastic film gravure water-based inks:
(The thin touch used is a Corona treated surface tension of 38 dyne/cm BOPP film)

Plastic film gravure water ink performance comparison table

The conclusions of the use of the three types of water-based gravure inks in testing and production: The main deficiency of 1# products is poor adhesion, slow drying, and can be used in production, but fundamental problems are not solved. The 2# product can be used on a 30-100m/min gravure press, but there is a lack of attachment fastness. The BOPP film printed with WE type water-based gravure ink was boiled (100°C) and boiled for half an hour. The BOPP film was taken out and blow-dried. The stickiness of the BOPP film was the same as that before boiling. It did not bleed, peeled, cracked, and did not fade. It was put into a 30% concentration of hydrogen peroxide solution at 40°C and then removed after drying for 2 minutes. The gloss was unchanged and the adhesiveness was unchanged. The use of production proof: WE type water-based gravure ink has fully met the requirements of the gravure printing machine production, has reached the international advanced level of similar products in the attachment fastness, drying speed, color concentration and gloss and other major performance indicators. .

Water-based plastic gravure ink use matters needing attention:

When used, water can be used to adjust the viscosity of the ink and control the viscosity of a 4-15 seconds/25°C coating. 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 water-based plastic gravure ink is used, the PH value should be controlled at 8.5-9, not too large or too small. Plates are either electro-engraved or laser-engraved, and the plate depth should be between 15 and 25 microns (the existing plate depth is typically between 35 and 55 microns). 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 appropriate, 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 2-3 minutes to wet the plate and agitation. 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 on the dry solid caused a stencil. 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. 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.

Waterborne plastic gravure ink use cost estimates:

The chlorinated and acrylic solvent type gravure printing ink is priced at RMB 20/kg, the alcohol-soluble gravure printing ink is priced at RMB 50/kg, and the water-based gravure printing ink is priced at RMB 40-50/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 cost of water-based gravure ink printing is slightly higher than that of solvent-based ink, but lower than that of alcohol-soluble ink, so the excellent cost-effectiveness of water-based concave ink is undoubtedly the best choice for color printing and packaging plants.

In summary, the plastic film gravure water-based ink is an alternative solvent-based ink to reduce alcohol-soluble gravure ink, is the inevitable trend of gravure printing development. Beijing Inco Chemicals Co., Ltd. launched WE type water-based gravure ink, the main varieties are: magenta (four-color version), yellow (four-color version), sky blue (four-color version), black (four-color version), White, big red, green, gold ink, silver ink, dilute agent, etc., is willing to work together with friends in the packaging and printing industry, mutual benefit and win-win, for our country's green packaging and printing services wholeheartedly.