Common measures to prevent ink crust

In the work of preventing ink crusting, the addition of an ink anti-skinning agent to the ink is a very important means. The following describes the scope and precautions for the use of printing ink anti-skinning agents:

The oxidation of printing inks, the oils of modified resins, the amount of pigments, fillers, driers used, the ambient temperature of the finished ink, the humidity, and other factors have a certain influence on the crust of the ink, and therefore are used. In the case of anti-skinning agents, the above factors must be taken into consideration. At the same time, attention should also be paid to the basic knowledge of the following seven aspects:

1. Adding amount

Generally calculated according to the ink material (because the main component of the crust is the main raw material of the ink) or calculated according to the total amount of printing ink, but also take into account the impact of other components.

Usually the amount of addition is between 0.1-0.3%. Because of the different temperatures and humidity throughout the year, the speed of the crust is different. Therefore, it is 0.1% in winter, 0.3% in summer, and 0.2% in spring and autumn. It depends on the composition of the formula to be scientific.

2. Ink film drying rate

We have proved in practice that in the offset printing ink made from alkyd resin, the amount of A, B and B is generally 1%. Although the drying speed is slightly longer, it is still within the standard range specified in printing. This is because the complex formed by the auxiliaries and the driers causes the driers to temporarily lose their activity. Therefore, it is different from the conventional principle of using a phenolic compound to freely terminate the polymerization reaction. Therefore, the effect of such compounds on the drying rate is not very large. If the amount is too much, the volatilization time is prolonged, and the disintegration of the complexes tends to slow the filming speed of the packaging printing ink.

3. Yellowing

Once the anti-skinning agent exceeds 0.3%, it tends to cause yellowing of the printing ink film. Especially when used in a white ink, yellowing occurs after storage for a long period of time. Therefore, the yellowing phenomenon can be avoided by strictly controlling the amount of addition or changing to butyraldehyde oxime.

4. Color degree

After the ink is added with the anti-skinning agent, the color of the ink is often directly affected. Generally, the effect of the varnish is greater than that of the color ink, and the white or yellow ink has greater influence than the deep color ink. In general, this phenomenon is difficult to observe by visual inspection and is independent of the added amount. Although we already know that the hue of ink film application has no effect after the film has been dried by the print graphic, the color image of the packaged print is in the presence of certain pigments such as amphoteric pigments and driers. There will be significant differences between the two, which will plague the hue. When we encounter this kind of situation, we should draw proofs continuously while making ink. We should do the test of color difference first. The purpose is to avoid the appearance quality of the ink film after the printing.

5. Printing ink film status

Although the anti-skinning agent does not have any influence on the state of the printing ink film, when the ink is stored for a long period of time, crystals are precipitated, resulting in turbidity after the ink film is formed and the gloss of the ink is affected. If the above mentioned materials are not properly designed with the binders, pigments, fillers and driers in the ink system, larger particles will appear. This should be tested before printing.

6. Luster and weather resistance

After the addition of the anti-skinning agent, the gloss of the printing ink is not only not affected, but also has gloss retention. Second, after adding the additive, the weather resistance of the printing ink film has been significantly improved and improved.

7. How to use

The anti-skinning agent is generally added at the time of ink adjustment and added at room temperature while stirring. For volatile inks, to control the ink, the coloring material is dispersed during grinding, dispersing and storage, particularly in the printing process, and a portion may be added during ink preparation, and it is preferable to add a portion before printing.

Above, we have made some discussion on the causes and treatment of ink crusts. In actual work, we may also encounter various problems of this kind or the same, but we understand the causes of ink crusts (mainly After the drying principle, the analysis should not be difficult.

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