Common problems and solutions for color box printing process

In the process of printing color Boxes, we often encounter problems such as blurred outlines of handwriting, corrugation collapse, ink filling between printed spaces, and poor overprinting/stack printing quality. In view of the quality problems that often occur in the production process of color boxes, here are some experiences and lessons accumulated by peers.

The ink-printed part of the paper is pulled or torn

Due to the different materials, paper structures and production processes of white paper, coated paper and offset paper, when the temperature is low in winter and the ink viscosity is high, the ink-printed part of the surface layer or coating layer of the white paper often becomes fuzzy or torn, which seriously affects the appearance quality of the printed product

Solution

You can add wetting powder and alcohol (5% to 20%) to the dampening solution to reduce the tension on the edge of the inked area, or choose the corresponding ink oil, detackifier or diluent according to different types of ink to reduce the viscosity of the ink.

Control the printing workshop and room temperature, generally controlled at 19℃ to 28℃. It is best to heat the ink appropriately in winter, which is conducive to improving the fluidity of the ink and reducing the viscosity of the ink.

Choose white paper with strong nap, and the printing pressure should not be too high.

The backing paper under the rubber blanket should not be too much, and the padding should not be soft. The rubber blanket should be cleaned with a cleaning agent after using it for a period of time.

Colored paper ink dries slowly

This phenomenon can easily cause the printed product to be damaged and bring some difficulties to post-processing. This problem can be controlled from the following three aspects.

Use base paper with slightly stronger ink absorption performance: for example, coated white board paper has stronger absorption performance than bleached noodle paper and white board paper in this regard.

Use quick-drying ink or add appropriate amount of drying aid according to the characteristics of the ink, and reduce the amount of ink applied to the inked area.

Appropriately extend the interval time for post-processing or spread the printed products to dry.

The same batch of printed products has different shades of ink and differences in color appearance

The following methods can achieve better results:

The ink required for the same batch of products should be prepared at one time. When mixing the ink, the required ink, diluent, debonder, desiccant and other additives must be measured with a scale, otherwise multiple mixing and random mixing will also cause differences in color.

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

The balance of water and ink on the printing roller should be well controlled, and the empty run should be strictly controlled, because after each empty run, the ink color of the first dozen or so printed products will be obviously darker and thicker. If the frequency of empty run is high, there will naturally be more printed products with different depths of ink.

For products that need to be overprinted multiple times, the previous base ink should be allowed to dry before subsequent overprinting.

Color printing products fade during post-processing and loading and unloading. From the surface phenomenon, the fading is mainly caused by the friction between products during post-processing and handling and loading and unloading. In fact, this problem is also closely related to the ink mixing method. In the production process of color printing products, we often find that the ink roller is unevenly inked and the printed products are damaged by ink due to excessive viscosity of the ink. To solve this problem, debonding agents are often added to the ink. If a debonding agent is used uniformly for inks with different characteristics, the fading phenomenon will be quite serious, because the characteristics of different types of inks are different. Take the 05 and 01 resin inks of Shanghai Ink Factory as an example. If the debonding agent used in the ink mixing is improper, it will cause the ink to crystallize (the ink printed on the product will have powdery characteristics) and cause serious fading of the product. Type 05 glossy quick-drying resin ink can only add type 0592 detackifier, and the amount added should be controlled within 3%, while type 01 resin ink can use 3% red drying oil and 6# ink oil to adjust its viscosity. Generally, do not add detackifier, otherwise it will also cause color printing products to fade.

In addition to the attention to the mixing of ink, the fading caused by dry friction between products and products, products and equipment, and products and tools should be controlled as much as possible during the post-processing and handling and loading and unloading of products, because when the ink is not completely dry, the dry friction resistance is poor, even the new RMB（paper money） will fade when it is dry-rubbed with rough paper.

If the product fades, the remedy is to cover the surface of the printed product with a layer of film or apply a layer of glossy paste to solve the fading problem.

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I have been engaged in the printing and packaging industry for more than 10 years. If you want to know other related issues about printing and packaging, please contact zhshprint@hotmail.com.