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Generation and elimination of packaging offset printing dirt release date: Source: China paper industry

in the packaging and printing industry, the current packaging and decoration offset printing products often have quality problems such as dirt, ink, paper wool, greasy, etc. we collectively call these quality problems dirt. Dirty quality problem is one of the stubborn quality problems of offset printing. We must analyze and study it carefully to find out the causes of the problems and the measures that should be taken. Today, China paper will introduce the related stains in detail from the packaging offset printing

we can analyze the dirt problem in the products of packaging and decoration offset printing from two aspects: 1. The plate itself is dirty, considering the weak downstream market (including printing), 2. The printing plate itself is not dirty, but caused in the printing process

printing plate

1 reason: poor version base or regenerated version; Treatment: replace the printing plate

2 cause: insufficient exposure of printing plate and aging of light source; Treatment: properly adjust the exposure time or replace the light source

3 reason: the transparency of Yangtu film is poor; Treatment: remake the positive film

4 reason: the developer concentration is too low and the development is not complete; Treatment: adjust the developer concentration to the standard concentration. Pay attention to adding new liquid at any time during the development process, and replace it after a certain period of time

5 reason: the blank part of the printing plate is oxidized; Treatment: plate coated with protective glue

6 reason: there are dust or dirty spots on the film film and the glass of the printing frame; Treatment: remove dust or dirty spots with detergent

7 cause: blisters adhere during development, and the developer orifice is blocked; Treatment: clean the developer spray hole

8 reason: the competitiveness of the printing market will also be further improved. The coating protective adhesive is too thin; Treatment: increase the concentration or thickness of protective glue

9 reason: there is much dust in the printing workshop; Treatment: the printing workshop and personnel should keep clean

10 reason: transparent glue edge marks are produced by manual Collage; Treatment: correct the edge trace of transparent glue

11 cause: the developer temperature is too low and the washing speed is too fast; Treatment: adjust the developer temperature and rinsing speed

12 reason: the protective glue of the printing plate is thin and there is sediment, which is dirty on baking; Treatment: change the thickness of protective glue, shake it evenly, wipe it evenly, and remove the sediment


1 reason: the downtime is long, and the printing plate is not rubbed with protective glue; Treatment: apply protective glue

2 reason: the blank part of the printing plate is not wet enough; Treatment: appropriately increase the amount of water

3 reason: the ink is too thin, resulting in flying ink; Treatment: add thickener or change new ink

4 reason: ink emulsification; Treatment: control the ink balance

5 reason: the pH value of wetting solution is generally 5. 0——6。 0。

6 cause: aging of rubber blanket; Treatment: first of all, replace the new rubber blanket with uneven installation of the pressure testing machine

7 reason: the pressure between water rollers is too light; Handle and adjust the pressure between water rollers

8 reason: the ink viscosity is too low; Treatment: add tackifier

9 causes: low surface strength of paper, too much paper powder and wool, and wear of printing plate; Treatment: reduce the viscosity of ink, wash the blanket frequently or change the paper

10 cause: the ink roller pressure is too heavy, and the hydrophilic layer of the printing plate is damaged; Treatment: adjust the pressure of the inking roller

11 reason: hands are not clean when using the printing plate, and there are fingerprints and sweat stains); Treatment: keep hands clean during operation

12 reason: the ink volume is too large, the ink layer of printing is too thick, and it is not easy to dry; Treatment: reduce the ink volume, and the ink layer reaches the standard density value

13 reason: poor dryness of ink itself; Treatment: add desiccant appropriately

14 cause: too much printing stacking and pressure; Treatment: reduce the stacking height

15 original 1 Jaw slipping; Because: there is dirt on the paper transfer drum or the imprint drum; Treatment: wipe the dirt on the paper transfer drum or imprint drum

16 reason: there are paper fragments in the machine, and the printed matter is encountered when printing; Handling: remove the broken paper in the machine

17 reason: the semi-finished products are not dry, moving and rubbing; Treatment: wait for the semi-finished product to dry out before moving

18 cause: dirty during paper transfer; Treatment: stick dirty paper or sponge strips

finally, there are two aspects of the dirt. One is plate making, which is called basic dirt. Another reason is printing, which is called groundless dirt. These two reasons are different, and the treatment methods are also different. Therefore, when analyzing dirt, the remedy should be tailored according to the actual situation. At the same time, we should constantly sum up experience to greatly improve the quality of packaging and decoration offset printing products

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