Kraft bag making techniques

Kraft paper printing can be flexo, gravure, offset, screen printing process, as long as a good grasp of printing technology essentials, familiar with the printing ink and kraft paper printability, reasonable selection and deployment of ink, control equipment parameters, can obtain the best quality effect .
However, for some small-scale packaging printing and processing plants, or small-scale plants that have just been put into production and management of kraft paper packaging, due to the limitations of various conditions, there will be some problems with product quality. Here are some points to note when printing kraft paper:
Note that in order to obtain better color reproduction in kraft paper printing, the printing color is more difficult than printing on SBS paper. In particular, accurate color reproduction on regular Kraft board requires more care than printing on bleached Kraft board. Because ordinary kraft paper itself is dark brown,
The effect of kraft printing inks is very different from that printed on bleached paper. Therefore, it is best to use bright colors of ink, use more eye-catching colors, such a printing effect is better. Soft colors and light colors are the most difficult to achieve the desired effects such as ink density, opacity, and abrasion resistance. In addition, if necessary, a little white can be added to the ink to help achieve the desired soft tone or light color, which is of great use for copying pastel colors and pastel colors. With the increasingly sophisticated printing technology, some manufacturers even use UV inks to effectively improve the printing color effect. At present, almost all ink manufacturers have developed inks for primary color paperboard, and many ink manufacturers have also developed inks printed on kraft paper. Therefore, before determining the best solution for the work, consult the ink manufacturer, select different formula inks according to the printing needs of the factory, refer to the ink chromatogram provided by the ink manufacturer and the printing effect of the ink on different papers, and finally determine the most used one. Good ink.
Reasonable ink selection Because kraft paper is different from SBS paperboard and general printing paper, it is uncoated, has looser porosity than paperboard after bleaching, has many pores on the surface, and has relatively strong permeability. This applies both to ink application and coating. Need to do comprehensive consideration. For example, according to the analysis of the characteristics of kraft paper, flexographic printing is generally preferred, and it is not preferable to use an offset printing press to print full-length kraft paper. Due to the rough surface of kraft paper, soft texture, strong ink absorption, and the color of printing products are dull, and the phenomenon that ink pulls down the paper surface fibers (also called detached paper hair) appears.
Due to the loose porous and large volume of unglazed kraft paper, the paperboard production process makes it easy to produce dust in the paperboard manufacturing process. Therefore, it is necessary to prevent and reduce the damage caused by dust.
The post-printing die-cutting process, due to its special structure of primary color kraft paper, is characterized by its high strength and predictable fiber properties, and it has better processing properties such as embossing, die-cutting and die-cutting. However, for high-strength and tough primary fibers, kraft paper is required to avoid rebound by deep indentation lines. In addition, the die cutter must be sharp. Due to the high strength of the kraft fiber, a narrow indentation is also required on the perforation line, and the need for nicks during punching should be less, and a small adhesive should be used to bond a high solid, high viscosity resin adhesive to Low-temperature bonding requires cooling before it can adhere to kraft paperboard. It cannot infiltrate into paperboard in large quantities. Traditional hot-melt adhesives are also suitable for kraft paperboard and kraft paper that has been coated with polyester. The effect is relatively good. Because of its light weight, Kraft board is suitable for high speed paste box machines.
Reasonable selection of paper In order to meet the new needs of food manufacturers for packaging, primary kraft paperboard has different characteristics from bleached paperboard, such as baked goods or convenience foods. The natural brown look of kraft paper has a healthy, retro appeal. In fact, the unique contrast of the unique appearance of kraft paper and the large amount of white packaging can also make the product more prominent. Since many food packages are designed to provide convenience or practicality, the strength of kraft paper is another advantage. The outer packaging must be strong enough so that it can contain the customer's meal without dropping it. By the same token, the beverage cup must also be able to remain in a moist environment so that it does not allow the coffee to flow onto the customer's thighs. Strength is also a major factor for frozen foods because the package of frozen foods cannot deform, tear, curl or absorb too much moisture in the freeze/thaw cycle. In terms of practicality in this regard, kraft paper is better than homogenous bleached kraft paper.

This information comes from China Packaging Bags Trading Network

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