In the printing process of the carton, we often encounter problems such as blurred handwriting, corrugated collapse, filling ink between imprinting gaps, poor overprinting/overprinting quality, and so on. In addition, how to deal with the problem of low-gram heavy base paper and how to print large corrugated cartons is also a technical issue that carton companies are very concerned about.

In view of the quality problems often occur in the production process of carton Pop up book, we will share some experiences and lessons accumulated by our peers as follows:

1. The ink part of the paper is pulled or broken

Due to the different material, paper structure and production process of whiteboard paper, coated paper and offset paper, when the temperature is low in winter and the ink viscosity is large, the hanging layer or coating layer of whiteboard paper often appears the phenomenon that the ink part is sticky or sticky, which seriously affects the appearance quality of printed matter.

solution

The wetting powder and alcohol can be added to the moistening solution (the proportion is 5% to 20%) to reduce the tension on the edge of the inking part, or according to different types of ink, choose the corresponding ink mixing oil, unstick agent or diluent to reduce the viscosity of the ink. The printing workshop and the room temperature are controlled, generally controlled at 19 ° C ~ 28 ° C is appropriate, and it is best to properly heat the ink in winter, which is conducive to improving the fluidity of the ink and reducing the viscosity of the ink. Choose whiteboard paper with strong drawing degree, and the printing pressure should not be too large. The liner paper under the rubber blanket should not be too much, and the liner should not be soft. After the rubber blanket is used for a period of time, the cleaning agent should be used to scrub it clean.

2. Color paper ink drying speed is slow

This phenomenon is easy to cause the printed matter to be glued, and bring some difficulties to the post-processing, this problem can be controlled from the following three aspects. Use base paper with slightly stronger ink absorption performance: such as coated whiteboard paper, the absorption performance of whiteboard paper is stronger than that of whiteboard paper in this respect. Choose fast drying ink or add the appropriate amount of drying additives according to the characteristics of the ink, and reduce the amount of ink in the inking part. Appropriate extension of post-processing interval time or spread the printing to dry.

3. Different shades of ink and differences in color appearance appear in the same batch of prints

Better results can be obtained by controlling it in the following ways:

The ink required by the same batch of products is best prepared at one time, and the required ink, as well as diluent, disadhesive, desiccant and other additives must be measured with a weighing device when deploying ink, otherwise multiple inks and random inks will cause color differences.

The absorption performance, whiteness and thickness of the base paper (white board paper) used in the same batch of products should be consistent, and the base paper with a large thickness will cause the printing pressure to increase, resulting in heavy ink, and the white background of the paper will also cause changes in the depth of ink and color appearance.

The ink balance on the printing roller should be controlled well, and the empty car should be strictly controlled, because after each empty car, the ink color of the first dozen prints printed is obviously deep and thick, and if the frequency of empty cars is higher, then the ink color of different colors will naturally be more.

For products requiring multiple overprints, the previous underink should be allowed to dry before subsequent overprinting.

4. The whiteboard is wrinkled when printed

When using white board paper to print color printing sheet, if the moisture content of the paper into paper is not uniform, there are flanged edges, wavy edges or tight edges due to excessive drying of the environment leading to more water evaporation on the edge of the paper, another set of printing color; After multiple printing wetting will make the whiteboard paper in the color printing process wrinkled.

In order to solve the wrinkles that appear in the process of color printing, we must first control the entry of water in the base paper. And the white board paper before printing on the machine, it is best to put it in the offset printing studio one to two weeks in advance, so that the moisture content of the paper and the humidity of the printing workshop balance. If the air humidity of the printing workshop is dry, it is best to spray some water on the ground to adjust the air humidity, to prevent more water evaporation on the edge of the paper and wrinkles caused by tight edges. The other is to replace or remove uneven base paper.

5. The color printing veneer appears droopy

The causes of the color printing veneer are the thickness of the paper, the direction of the silk flow of the paper, the solid content of the adhesive, the amount of glue on the corrugated peak, the pressure after the veneer, and the water content of the cardboard.

The problem of dew can be controlled in the following ways:

Appropriately improve the gram of color printing paper, and use the base paper after absorption of water transverse expansion is greater than the characteristics of vertical expansion, the longitudinal silk flow of color printing paper and corrugated into a "+" font cross fit.

Improve the solid content of the adhesive, reduce the moisture in the adhesive, and adjust the gap between the sizing roller and the pressure roller of the veneer (or the laminating machine), and minimize the amount of sizing on the corrugated peak under the condition of ensuring good bonding between the color printing paper and the corrugated. After the veneer is dried, the water is controlled at 9± 2% to shrink the fibers of the color printing paper, which can also reduce the dew.

6. The veneer appears unglued or corrugated collapse

Veneer adhesive is now generally used most of the oxidized starch adhesive, if the oxidized starch adhesive in the preparation process of starch oxidation is not enough, or starch oxidation is too deep, will cause the quality of the adhesive is unstable, resulting in opening. In addition, if the sizing amount is adjusted too small, resulting in too little sizing on the corrugated peak will also appear unglued. If it is a hand-mounted veneer, each layer of tile paper or the paper inside the face is not mounted smoothly will also lead to unadhesive.

Veneer on the veneer machine; Or use hand gluing veneer, if the amount of glue on the corrugated peak is too large, it is easy to cause the corrugated to absorb too much glue and become soft, and the corrugated collapse will occur after sticking with the face paper under pressure. In addition, too much sizing not only wastes glue, but also causes the product difficult to dry after the veneer. Therefore, the amount of sizing should be strictly controlled.

7. Color printing products fade during post-processing and loading and unloading

From the surface phenomenon, the fading is mainly caused by the friction between the product post-processing and handling process, in fact, this problem is also closely related to the deployment of ink methods, in the production process of color printing products, we often find that the viscosity of the ink roller is too large, causing the ink roller to be uneven and the print is ink sticky hair sticky. In order to solve this problem, often add unstick agent in ink, if the ink with different characteristics of a unified use of an unstick agent, then the phenomenon of fading will be quite serious, because the characteristics of different types of ink are different, to Shanghai ink factory type 05 and 01 resin ink as an example, such as the use of improper unstick agent when mixing ink, It will cause ink crystallization (the ink printed on the product appears powdery characteristics) and cause the product to seriously fade. Type 05 light fast drying resin ink can only add type 0592 adhesive, and the amount should be controlled within 3%, while type 01 resin ink can use 3% red dry oil and 6 # ink oil to adjust its viscosity, under normal circumstances do not add adhesive, otherwise it will also cause color printing products fade.

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