Application of gravure printing ink on plastic flexible packaging

Gravure ink refers to the ink used when the gravure printing machine prints various different substrates. It is also divided into paper gravure ink and plastic gravure ink. In the plastic gravure printing ink, there are two types of intaglio printing ink and printing ink composite printing.

Plastic gravure inks are generally used to print plastic inks such as PE, PP, OPP, NY, etc., but they can also be printed in composite flexible packaging, as long as the print layout does not have large color patches, after rewinding the cold wind test, the composite smell and jail Degree is still basic. Plastic gravure printing ink is mainly made of a binder, polyamide resin, plus pigments and additives, etc., through grinding and filtering. The softening point of the polyamide resin is controlled at 121°C, otherwise the adhesion of the print will occur when the softening point of the resin is low during printing in the mildew season. When the softening point of the resin is high during use in winter, it will freeze, and it will be heated and mixed to make it melt. The dilution solvents for plastic gravure printing ink are toluene, isopropanol, xylene, butanol, etc. Some ester solvents may also be added in time to adjust the viscosity of the ink. Toluene and isopropyl alcohol are fast drying solvents. Xylene, butanol is a slow-drying solvent. When using butanol, it should be noted that if the ink is dried too fast, resulting in the loss of the image and text points, proper addition of butanol makes the ink reproducible, and the small print and dot are clear. However, adding more ink will cause the ink to quit, especially during the mildew season. There will be anti-adhesion of prints.

Plastic intaglio printing ink, also known as composite ink, refers to the ink printed inside the substrate. The binder of this ink is mainly chlorinated polypropylene resin, which has high adhesion to printing OPP, PET, NY and other films. After compounding, the black ink is sandwiched in the inner layer and is a high-grade plastic soft bag ink. The main solvents used for dilution include toluene, ethyl ketone, butanone and ethyl acetate. Methyl ethyl ketone, toluene, and ethyl acetate are fast-drying solvents. Butanone is a slow-drying solvent. Such inks should not be added with alcohol solvents, otherwise the ink will deteriorate. When using plastic gravure compound inks, care should be taken because ink manufacturers have the difference between high-speed machine fast dry ink and low-speed machine slow dry ink when designing ink. When printing, the choice of ink should be determined by the rotation speed of the gravure printing machine. Otherwise, the rotation speed of the gravure printing machine is slow, and the ink is dried in the pits of the gravure network; the gravure printing machine can not dry quickly after the printing speed is high.

For retort-resistant plastic flexible packaging or printed foils, choose two-component gravure-resistant gravure inks and foil-specific inks. Otherwise it will not be resistant to cooking, there will be compound after the inner layer of the ink after cooking thinning, discoloration, the picture is not clear and so on. In the production of retort pouches also need to choose high-temperature materials and cooking resistance of two-component adhesive.

The surface tension of plastic gravure ink is generally 36 dyne, while the surface tension of PE and OPP is generally only about 32 dyne. This requires that in gravure printing, the film undergo corona treatment to destroy the molecular structure of the plastic surface and improve the film. Surface tension, so that it reaches 38 dynes or more, so that ink and film affinity and adhesion, hand smashed and adhesive tape can not tear the ink before they meet the printing quality requirements.

Plastic gravure inks have effects on the ozone layer due to chlorinated polymers in production. Toluene is used in gravure printing to dissolve and regulate the viscosity of inks, which is harmful to the health and safety of workers. This requires ink manufacturers to develop them as soon as possible. Low toxicity, non-toxic alcohol-soluble and water-soluble gravure plastic printing ink. We use plastic flexo inks in the production of paper-plastic composite webs (for users to self-assemble machine-packed pharmaceuticals, tea bags, etc.) and the production of liquid packaging film webs. This ink is drunk-soluble, and the solvents added are alcohols and esters, which have low toxicity and achieve odorless and benzene-free hygiene requirements.

In short, the selection and application of plastic gravure printing inks depends on many factors such as the performance of different gravure printing machines and the proficiency of operators. To know what material is printed on, what is the speed of the gravure printing machine, how fast the ink is dry, whether the printing color matches the original, and whether the post-press processing meets the requirements and the purpose of the final product. Different inks should be used for different specifications and different plastic flexible bags (films). Only by choosing suitable inks and materials, and careful operation, can we produce beautiful plastic printing products.