Kraft paper packaging skills

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 the production and operation of kraft paper packaging, due to the limitations of various aspects, there will be some problems with product quality. Here are some points to note when printing kraft paper:

Pay attention to printing color:

In order to get better color reproduction in kraft printing, there is a certain degree of difficulty in printing than using SBS paper. In particular, accurate color reproduction on regular Kraft board requires more care than printing on bleached Kraft board. Since ordinary kraft paper is dark brown in itself, the effect of printing ink 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 most difficult to achieve the desired effects such as ink density, opacity, and abrasion resistance. In addition, if necessary, adding a little white to the ink will help to achieve the desired soft or light color, which is of great use for copying pastel and pastel colors. With the increasing maturity of 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 choice of ink:

Since kraft paper is different from SBS paperboard and general printing paper, it is uncoated, has looser porosity than the paperboard after bleaching, has many pores on the surface, and has relatively strong permeability, which needs to be integrated in the application and coating of ink. consider. For example, according to the analysis of the characteristics of kraft paper, flexographic printing is generally preferred, and it is not appropriate to use an offset printing press to print full-length kraft paper. Due to the rough surface of the kraft paper, soft texture, strong ink absorption, and dull colors of the printed products, the phenomenon that the ink pulls off the paper surface fibers (also called detached paper hairs) may occur.

Cardboard production processing:

Due to the fact that unglazed kraft paper is porous and bulky, it can easily generate dust during the processing of paperboard. Therefore, it is necessary to prevent and reduce the damage caused by dust.

Post-press cutting:

Due to the special structure of the primary color kraft paper, its strength and predictable fiber characteristics allow it to have 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. In addition, the die cutter must be sharp. Due to the higher strength of the kraft fiber, a narrower indentation is also required on the perforation line, and the required nicks for punching should be less and smaller.

Adhesive glue reasonable:

High-curing, high-viscosity resin adhesives are suitable for low-temperature bonding and require cooling before they can be attached to kraft paperboard. They cannot penetrate into cardboard in large quantities. Conventional hot-melt adhesives are also suitable for kraft paperboard and polyester glazing papers. it is 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 some features different 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 homogenized bleached kraft paper.

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