February 6 KBA, we issued a "Cai Chengji: film screening methods gravure ink painting (click to see)" article, has been widespread concern in the industry, which details the ink film laboratory tests, which is the enterprise screening Ink The important basis, however, should the enterprise pay attention to the food packaging in the actual application process of ink and wash? In this article, Mr. Cai Chengji will systematically sort out the “quality problems in the application process of gravure film ink†to help everyone recognize Clear the problem and take less detours. Book printing Ink film formation differs greatly from solvent ink film formation. After the solvent ink is transferred onto the film, the solvent volatilizes the ink supply , and the remaining resin is deposited into a uniform ink film. In the ink, due to the presence of the emulsion, the first stage after transfer to the film is the accumulation of particles, which are then closely arranged with the volatilization of moisture, and then deformed, and finally the ink film is formed. The solvent ink to generate an ink film only two stages of layout design, while the ink has an ink film to generate four phases. The formation of different ink films constitutes several fundamental quality problems in the application of ink, namely, the horizontal leveling of ink, the tailing of ink due to insufficient drying, and the pinhole defects of ink. As for the defects existing in the gravure itself, the defects which are entangled when using the solvent type ink are not listed here. Tangshan Yuyin 1. Field leveling paper The metal packaging in the field leveling problem, that is, the original solid compact and solid grounding features of the gravure field have disappeared, and regular white spots appear in the field printing . Founder The fundamental method to be solved is to add a co-solvent, which serves to improve the deficiencies in the emulsion process of the aqueous resin, and to reduce the side effects of the emulsifier in the aqueous emulsion manufacturing process. During the drying process of the ink film, the co-solvent can dissolve, deform and fuse the polymer particles into a continuous ink film flexo , which has a dissolution effect on the resin and a short plasticizing effect, which can significantly improve the leveling in the field. The amount of cosolvent added should not exceed 5%. Excessive cosolvent will soften the ink film and affect the strength of the ink film. Laminating Gravure pass grooves can be used to improve gravure solid leveling. The left and right columns of Figure 1 are respectively an electric gravure and a laser intaglio. Electric carving gravure groove may be improved through an angle based on the characteristics arise, such as the through-groove angle of 30 ° to 45 ° angle occurs earlier international Akiyama, 60 ° angle hardly occurs through the grooves. The laser concave version is likely to have no through grooves, but it can be made through the custom editing of the dots. Passage can improve leveling in the field. Printer tour Figure 1 Different groove printing accessories for gravure 2. The ink drying performance deficiencies caused by poor dry reviewer Insufficient dryness caused by poor drying performance of the ink will cause ink residue at the trailing edge of the dot or the trailing edge of the solid color block, as shown in Fig. 2. Adobe Figure 2 Tail policy and regulations formed by insufficient ink and wash surface The method of thinning the ink film is effective, and the measure of reducing the plate depth is feasible. Version shallow depth of investment purchases, the ink film thinning, will speed up the drying volatile, but must re-adjust the gravure reduction curve, so as to achieve substantially the same color density and level of reduction. cosmetic packaging Pre-drying the ink in the intaglio with hot air can make it shrink and lay off , which can effectively solve the tailing. Please note that lengthening the drying tunnel is not effective for this problem. The long drying tunnel only solves the problem of dry cleaning, which is ineffective for insufficient drying, and also increases the risk of registration due to thermal deformation of the film. Digital publishing The solution with a non-solvent dry the ink over- packing, to achieve the same level of solvent-based inks, even better than in the highlight region solvent-based inks. Figure 3 shows the case of using the traditional electro-engraving gravure depth (note, not the shallow version) in the 5%, 25%, 40%, and 60% areas, and there is no dark adjustment of adjacent dot adhesion at the beginning of entering the dark adjustment area. There is no dry version at 3% of the high-gloss small dot. Digital printing machine Figure 3 Improved ink gravure dot tobacco packaging 3. Ink pinhole Beiren shares Please pay attention to the difference between the ink pinhole and the whitening caused by the blistering of the ink. Ink needle holes can detect package printing under laboratory conditions, and the on-machine printing cannot be significantly improved. There is no significant difference between the polarity of the film used and the surface tension value. The ink pinhole is shown in Figure 4. Postpress equipment Figure 4 ink needle hole color sequence The reason for the ink pinhole is the unreasonable matching of the emulsifier and the antifoaming agent, which should be screened first in the laboratory screening, which is a problem of the ink itself. Ink defoamers must be based on the characteristics of the aqueous emulsion choice, especially if you choose feed according to the characteristics of emulsifiers, defoamers must match with the emulsion system, compatible. Excessive addition of defoamer will cause pinholes in the ink film, and a reasonable defoamer addition process needs to be considered at different viscosities. Variable data printing Ink film pinholes are the performance and quality issues of ink, and must be completed only by ink manufacturers. Printing companies can use laboratory screening to determine products that use reasonable defoamer formulations and processes. The solution to solve the ink pinhole at the printing site: digital printing with defoamer as little as possible, and measures to reduce ink shear in the ink and reflow units, such as reducing the kinetic energy caused by the impact of ink in the ink tank, reducing ink The potential energy caused by the return from the ink tank to the ink tank. Reducing the probability of using the defoamer will effectively avoid the generation of ink pinholes. Northwestern Shaanxi Portable Baby Booster Seat,Baby Feeding Chair,Portable Baby Chair,Kids Study Chair Zhejiang Lamon Technology Inc. , https://www.baby-chair.com
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