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        Industry News

        Aluminized film packaging printing failure and processing method

        Word:[Big][Middle][Small] Mobile page qrcode 2019-1-24     Viewed:    
          As we all know, the main purpose of vacuum aluminum-plated film is to replace the pure aluminum foil composite, so that the flexible packaging printing has an elegant silver-white luster, and improve the barrier property and light-shielding property of the flexible packaging film bag, and reduce the packaging printing cost (aluminized The film meter is 0.4~0.6μm, which is only about 1/150) of pure aluminum foil.

          There are two kinds of vacuum aluminum plating methods: one is vacuum aluminum plating after printing, that is, reverse printing is performed on the surface of the film, then aluminum is plated, and then composited with the base film; second, directly on the surface of the film. After printing, the vacuum-aluminized base film is dry-composited. However, the base film of this method must use materials such as CPP and PE which have good heat resistance and can be heat-sealed. Regardless of the method used, the packaged printed product after the composite is not peeled off or degummed to be provided to the customer as a finished product. As the product continues to expand, packaging printing quality and delivery time requirements are constantly increasing, while the selling price is gradually falling. For the packaging and printing enterprises, under the premise of on-time delivery, it is a priority to choose the low cost of raw materials as much as possible. For example, when using ink or glue, it is preferable to purchase a low-priced auxiliary material that is not profitable after purchase. Therefore, almost no one has to check and accept the purchase channels, which obviously leads to the inferiority of the printed and printed products of the aluminized film and the failure of scrapping. Around this issue, the author introduces the causes and treatment methods of the following faults in order to cooperate with the packaging and printing colleagues.

          For example, PET film, printing ink, vacuum aluminum plating, rubber coating and PE (as heat sealing base material) are combined. As a result, after the color ink is printed, the full-print white ink (or yellow ink) printed on the adhesive is all bonded to the adhesive, resulting in Separation of PET from the base film (seed): There is also a case where the ink layer of the printing ink is thin, the adhesion is good after compounding with the PE of the base film, and the adhesion (poor) of the ink film layer is poor.
        In view of the above failure, the former involves a low softening point of the oiler (not heat resistant), and has a good affinity (admissibility) with the adhesive, and the composite PET film is easily peeled off; the latter is due to the ink. The content of the cotton liquid in the system is too high or the surface dispersing agent and the waxy auxiliary agent are increased. When it is combined with the PE film, it is repellent and the adhesion is poor, and it is easy to tear.

          We know that in the usual packaging printing process, in order to save ink costs, color inks often use lower-priced gravure inks. For example, polyamide ink, acrylic ink, nitro ink, chloroacetic resin ink, etc. can be printed as a dry-type composite printing ink for polyurethane glue, while white ink uses printing ink, and all use surface printing ink or color ink. Ink is printed with ink, while white ink is printed with surface printing ink. No matter what kind of ink printing is used during printing, it must be clear that some inks should be repelled with the composite glue, so it is necessary to use a certain compatibility of the ink compound glue.

          For example, in the case of a polyamide ink, when a white polyamide ink is used as a printing ink to print a base color, the above-mentioned failure is generally not caused by a composite ink or a composite adhesive layer as long as it has a certain adhesive force. However, most of the surface inks have no affinity with the composite ink or the composite adhesive layer, and it is difficult to produce a binding force. Therefore, the ink is detached from the (anti-printing) ink film layer of the composite color ink. In addition, in the production of white ink, the amount of the coloring agent-titanium white powder or a small amount of calcium powder in the system is mostly between 20% and 33%, and the coloring agent of the color ink is used in an amount of 8% to 12%. Many, if we use the same amount of resin binder, the adhesion will be greatly reduced for color inks. For this reason, when the white ink is used, it should be selected with a large amount of resin binder or no surface-active auxiliary agent, so that the adhesion fastness of the color ink is as large as that.
         
          The author has already introduced the packaging printing method of aluminum-plated film and the principle of selecting ink and bonding compound. However, this does not mean that only the white ink with a large content of resin binder can have sufficient adhesion fastness. The white ink adhesion strength is also affected by the surface active dispersant in the ink system and the anti-settling and anti-friction wax. The material and the ink itself are static and so on. We know that once the glue is applied to the surface of a white base ink film containing a surface active dispersant or a anti-settling, anti-friction wax additive, the substrate will be repelled or the wax will be almost free. The surface glue layer forms a uniform dot, resulting in a low-quality package printed article having poor composite fastness or low composite strength.

          Secondly, due to the use of packaging printing inks with a lower softening point, when high temperature environment is applied during aluminum plating or compounding, the ink is easily pulled by glue with higher softening point or miscibility (solubility). Causes the occurrence of skin failure.


          Third, due to the large amount of film-forming hard resin in the surface printing ink system (such as the nitrocellulose auxiliary resin in the polyamide ink system), the printing ink of the printing ink is often lost. Flexibility, the result is that the ink film is thin and the composite is well adhered, and the adhesion of the ink film is poor.

          Fourth, the adhesion of the ink to the glue is not good, and the solvent residue of the ink system or the glue system is too large. The difference in adhesion between the ink and the substrate is caused by a small surface tension of the substrate or an imbalance in the evaporation gradient of the solvent of the ink system or a too small viscosity of the ink (the resin content is too small).

          As for the adhesion of the glue to the composite base film after printing, the substrate is not treated well or the ammonia bond value of the glue is too different from the ammonia bond value of the substrate.


          The methods for dealing with the above faults are generally: 1 processing the substrate; 2 re-changing the glue; 3 selecting an ink having affinity with the glue; 4 switching to an ink having a high resin content or a high viscosity; 5 using a constant temperature (heat) Ink; 6 select printing ink without surfactant or wax; 7 gravure to change the plate with shallow mesh; 8 change the viscosity of high or large amount of glue; 9 control aluminum plating, drying tunnel , compound temperature; 10 increase the printing pressure or pressure between the pressure roller.

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