Vacuum Aluminized Film Packaging Printing Faults and Handling

As we all know, the main application of vacuum aluminum film is: instead of pure aluminum foil composite, the soft packaging printing material has an elegant silver-white luster, and at the same time improve the barrier property and shading of soft film film bags, at the same time reduce the packaging printing cost (aluminum plating The thin film meter is 0.4~0.6μm, which is only about 1/150 of pure aluminum foil and about 25%.

There are two typical vacuum aluminum plating methods: First, vacuum aluminum plating after printing, that is, reverse printing on the surface of the film first, then aluminum plating, and then composite with the bottom film; second, directly on the film surface After being printed on the inside, it is dry-composited with vacuum-plated aluminum backing film. However, in this method, the base film must be made of materials such as CPP and PE that have good heat resistance and can be heat-sealed. No matter what method is adopted, the combined packaging and printing products can be provided as customers without peeling or degumming. With the continuous expansion of the product, the requirements for packaging printing quality and delivery time are constantly increasing, and the selling price is gradually falling. For packaging and printing companies, on the premise of on-time delivery, choosing raw materials as low cost as possible is a priority. For example, in the use of ink, glue, it is rather cheap to buy, will not purchase useless materials after use. Therefore, almost no one to check, acceptance of the purchase channel, apparently lead to inferior packaging and printing of aluminized film products and scrapped one of the fault is from the plastic, peeling. Focusing on this issue, the author introduces the causes of the following failures and their handling methods so that they can deal with packaging and printing.

For example, PET film, printing ink, vacuum aluminum coating, gluing, and PE (as the heat seal substrate material) are compounded. As a result, after the color ink is printed, the full-printed white ink (or yellow ink) is completely adhered to the adhesive. Separation of the PET from the base film (skinning): There is also a case where the ink layer of the printing ink is thin, the attachment fastness after the composite with the PE of the base film is good, and the adhesion (badness) of the ink film layer is poor.
In view of the above failures, the former involves low oil-softening point (insufficient heat resistance) and good affinity (adhesiveness) with the adhesive. The composite PET film is easier to tear open; the latter is due to the ink. If the content of the system cotton is too high or the surface dispersant and the wax additive are increased, repulsion and poor adhesion will occur when compounding with the PE film, and it is easy to tear.

We know that in the ordinary packaging printing process, in order to save ink expenses, color inks often use lower-priced epitaxial gravure inks. Such as polyamide ink, acrylic ink, nitro ink, vinegar resin ink, etc., almost all can be used as polyurethane adhesive dry composite surface printing ink, while the white ink is printed ink, but also all use the table printing ink or color ink The ink is printed on the inside, while the white ink is printed on the surface ink. No matter what kind of ink printing is used in printing, one thing must be clear. To prevent some inks from repelling with the compound glue, we must use the ink compound glue with a certain degree of compatibility.

For example, polyamide ink, when white polyamide ink is used as the printing ink to print the background color, the above failure will not occur as long as the composite ink or the composite adhesive layer has a certain adhesive force. However, most surface inks do not have affinity with the composite ink or the composite adhesive layer, and it is difficult to produce adhesive force. Therefore, the ink ink layer with the composite ink (off-printing) is detached. Furthermore, in the production of white ink, the amount of the colorant titanium dioxide or a small amount of calcium powder in the system is mostly between 20% and 33%, and the amount of the color ink used in the color ink is between 8% and 12%. A lot, if we use the same amount of resin binder, the adhesion will be greatly reduced for color inks. Therefore, when the white ink is used, the resin binder content should be high, or there should be no surface active agent, so that there will be a large adhesion adhesion fastness of the color ink.

Above, the author has introduced the method of packaging and printing of aluminized films and the principle of selecting inks and adhesive composites. However, this does not mean that only the white ink with a large content of resin binder can have sufficient adhesion fastness, and the surface active dispersant and anti-settling and friction-resistant wax in the ink system are also affected. Material and ink itself are static and so on. We know that once the glue is applied on the surface of a white ink film containing surface-active dispersants or anti-settling and anti-friction wax additives, waxes that are repelled by the two materials or hardly pull will make printing The glue layer on the surface forms a uniform dot, resulting in a low-quality packaging printed product with poor composite fastness or low composite strength.

Second, due to the use of packaging printing inks with a lower softening point, the ink can be easily pulled by a glue with a higher softening point or miscibility (solubility) when the aluminum plating or compounding is performed in a high temperature environment. Causes the appearance of peeling faults.

Thirdly, due to the printing ink of the film-forming hard resin content in the table printing ink system to a certain amount (such as the nitrocellulose auxiliary resin in the polyamide ink system), the graphic ink film adhesive of packaging and printing ink will often lose certain Flexibility results in a good adhesion of the ink film where the film is thin, and poor adhesion of the film where the ink film is thick.

Fourthly, the reason why the adhesion of the ink and the glue is not good is that the residual amount of the solvent in the ink system or the glue system is too large. The poor adhesion between the ink and the substrate is caused by the small surface tension of the substrate or the unbalance of the volatilization gradient of the solvent in the ink system or the low viscosity of the ink (too little resin content).

As for the adhesion of the adhesive after coating with the composite backing film, the substrate is not treated properly or the ammonia bond value of the adhesive is too different from the ammonia bond value of the substrate.

The methods to deal with the above-mentioned faults are generally as follows: (1) handling substrates well; (2) repurposing glue; (3) selecting inks that have affinity with glue; (4) using inks with high resin content or high viscosity; (5) using resistant temperature (heat); The ink; 6 choose printing ink that does not contain surfactant or wax; 7 Gravure printing to use shallow printing plate; 8 exchange the glue with high viscosity or large amount of coating; 9 Control the aluminum plating, drying the road , Composite temperature; 10 to increase the printing pressure or pressure between the pressure roller.

Source: China Packaging Line

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