Causes and remedial measures for shrinkage of the

Causes and remedial measures of printing ink film shrinkage

shrinkage is one of the faults of packaging and printing ink film due to poor leveling. After ink printing, the wet ink film shrinks into a small circle in the leveling process, exposing the substrate material (Jin Min has also customized and developed noble, high-end, gorgeous non spray materials with different colors for high-end cosmetics packaging and wine packaging) or an ink layer. The production of polyurethane foam and the development of products are gradually developing in the direction of lightweight, multi hardness, low odor, low haze, aging resistance, storage stability and more environmental protection; The main reason for the third shrinkage is that the surface tension of the upper and lower parts of the printed ink film is different. Some people think that a wet ink film can be regarded as a double-layer liquid ink film. In the film-forming process, when the surface tension of the upper wet ink film is lower than that of the lower wet ink film, shrinkage occurs, which is due to the wetting of the substrate material. Sometimes when this phenomenon is about to happen, the wet ink film loses its fluidity and happens to inhibit the occurrence of shrinkage. For example, in some gravure or iron offset printing operations, with the rise of temperature, the wet ink film has fluidity, which may cause secondary shrinkage

theoretically, the remedial measure is to improve the flow and leveling of the wet ink film. The surface tension of the ink should not only be low, but also the wettability of the substrate material is better. Because there is a tension difference between the upper wet ink film and the lower wet ink film, the surface tension of the system decreases after packaging and printing, so that the printing ink will self develop into a complete ink film. For the shrinkage failure, the specific methods are as follows: ① add leveling agent appropriately into the printing ink; ② Use solvent with low surface tension; ③ Wet the surface of the substrate (for example, wipe the surface of the substrate with solvent before printing); ④ Control the ambient temperature and humidity of printing operation; ⑤ Choose the appropriate explanatory agent; ⑥ Reduce the surface tension between the printing ink and the substrate carrier, so that the ink and the carrier have good wettability, so that it will not form a surface tension gradient with the material causing shrinkage); ⑦ Adjust the evaporation rate of solvent, reduce viscosity, improve the fluidity of ink, and extend the leveling time; ⑧ A very thin monolayer is formed on the surface of the experimental standard ink film of packaging printing ink to provide stable and uniform surface tension

in order to correctly select the anti shrinkage agent of printing ink, the selection of various anti shrinkage agents is briefly introduced below

solvents: generally refers to mixed solvents with high boiling points, which are both a good solvent and a good wetting agent for pigments (shrinkage due to poor solubility of ink (film-forming) due to solvent volatilization, or boiling marks, bubbles and other defects in baked iron offset printing inks)

resins: there are generally cellulose acetate, especially polyacrylate anti shrinkage resins with limited compatibility. Its dosage is: acrylic resin 1% ~ 1 5%, epoxy resin 0 5% - 1%, polyester resin about 1%

silicone resins not only have the functions of anti shrinkage, but also have the functions of leveling, anti floating and anti foaming. For example, domestic xh204 water-based silicone oil in water-soluble acrylic ink helps to promote the flow, leveling and brightening of printing ink

in addition to the above anti shrinkage agents, there are silicon free fluoro surfactants belonging to polymer surfactants, which are also very effective in preventing the shrinkage of ink film, improving leveling and improving the gloss of printing (Graphic) ink film

preventing the shrinkage of ink film of packaging and printing ink is an important measure to improve the effect of ink on packaging and printing decoration. The purpose of using different anti shrinkage and leveling agents is to improve the printing quality and extend the grade of printing (surface ink film)

although they have many varieties and types, their uses are limited by the catalogue of foreign-invested advantageous industries in the central and western regions. Sometimes even the improper dosage or use will not only make it difficult to achieve its due effect, but also bring side effects

years of practice have proved that before use, different varieties and dosage should be strictly screened and tested to find the best variety and the most appropriate dosage. In addition, a more scientific technological process should be selected through batch comparative tests, even including the addition and application methods in the process to be printed. Only in this way can we continuously improve the product quality of packaging and printing products in our country, and accumulate richer theoretical knowledge in practice