Environmentally-friendly, non-toxic plastic film gravure water-based 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 high speed of gravure printing requires the use of highly volatile inks to meet the printing requirements, making gravure printing a particularly prominent environmental issue in all printing processes. Alcohol-soluble plastic gravure inks have low odor and no benzene, which can effectively reduce the influence of residual solvents on the quality of packaged foods. However, there are still problems with solvent residues. It is gradually being promoted, but the cooperating performance with the gravure printing machine and the quality of the printed product still need to be improved. Water-based gravure inks for plastic films have only just begun to be used. It is an environmentally friendly liquid ink made from 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. The products printed with water-based inks are completely non-toxic, and the production environment is environmentally friendly. The biggest feature is the reduction of the emission of organic volatile substances voc into the atmosphere. Water-based inks are the only non-toxic inks approved by the U.S. Food and Drug Association.

Plastic film gravure water-based inks are finely processed from water-soluble resins, high-grade pigments, additives and water. The water-soluble resin evenly disperses the pigment, provides adhesion to the substrate and forms an ink layer. Pigments can absorb, reflect, refract, and transmit light and present a certain color. Various additives enhance and improve the performance of the oil film. Water-based ink solvent is water and a small amount of ethanol, using water-based ink to get rid of organic solvents other than alcohol.

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 rotogravure printing machine in PE, PP, PET, PVC and other film printed food bags, fresh milk packaging bags, medicine packaging bags, candy bags, beverage bags, toy packaging bags, etc. . Adapt to print speed 20 to 100 meters/minute.

According to relevant reports, the National Certification and Accreditation Regulatory Commission will place food packaging/container products under the category of compulsory certification (hereinafter referred to as “3C certification”), and will be implemented from the second quarter of this year. At present, it has begun to accept applications from companies. Starting from 2006, the product certification control system (3C certification) will be enforced and must meet the hygienic standards for composite food packaging bags. Only plastic food packaging products that meet the 3C certification standard can be listed. This standard is aimed at all food packaging companies, including plastic products, paper products, composite packaging products, and glass ceramics. This standard requires that companies manufacturing food packaging materials must implement this mandatory standard from the procurement of raw materials to the production process, to the production, the safety of the human body during the use of the products, and the safety of the waste after use to the environment. This is a great challenge and a great opportunity for color printing and packaging companies and ink production companies.

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, 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 flexographic printing is also rapidly growing in China, and the proportion of inks in flexo presses is increasing. 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.

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 gravure presses of 30 to 100 meters per minute, but there is a lack of attachment fastness. 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 it was not boiled. 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. .

Plastic film gravure water-based ink use matters needing attention:

When used, the viscosity of the ink can be adjusted with water, and the viscosity of the coating-4 can be controlled for 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 microns. The existing version is generally 35 to 55 microns 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 °C ~ 60 °C is appropriate, and the air volume is large, so that the ink transferred to the film is quickly 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.

Color printing and packaging plant selection and requirements for plastic film gravure water-based ink: water-based ink cost is better, high color, hue stability, high gloss, fineness controlled below 15 microns, viscosity (coating 4 cups) 15 to 25 seconds, adhesion strength To be high, able to adapt to the needs of high-speed printing, drying faster.

Waterborne plastic gravure ink use cost estimates: chlorinated and acrylic solvent type gravure ink price 20 ~ 30 yuan / kg, alcohol soluble gravure ink price 50 yuan / kg or so, water-based gravure ink price 40 ~ 45 yuan / kg. As the ink printing plate is shallow, the depth of the printing plate is 15 to 25 microns, and the ink consumption per square meter of ink is 50% to 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.

Conclusion: Plastic film gravure water-based ink is an alternative to solvent-based ink to reduce alcohol-soluble ink, is the inevitable trend of gravure printing development. The main types of WE-type plastic film gravure waterborne inks with complete independent intellectual property rights (State Intellectual Property Office Patent Application No.3) launched by Beijing Incofan Chemicals Co., Ltd. are: Magenta (four-color version), Medium-yellow (four-color Edition), sky blue (four-color version), black (four-color version), white, red, green, gold ink, silver ink, diluting agent, etc., is willing to work together with friends in the packaging and printing industry, mutual benefit and win-win situation. China's green packaging and printing service wholeheartedly.

Author: Beijing Branch Fan Ying Ma Wo Chemical Products Co., Ltd.

Source "Packaging Materials and Containers"