The whole process of packaging and printing of the

The whole process of wine box packaging and printing

in modern society, people are increasingly pursuing beauty, so wine boxes with exquisite production and elegant shape are popular. But in actual production, from design, plate making, printing, post press processing to finished products, almost no product can complete these processes flawlessly. Here are some common problems in the production process and the corresponding treatment methods to discuss with the majority of peers. Plate making

overprinting is not allowed

1) when making up, if the position between graphics and texts or regular lines is not matched properly, it is difficult to achieve accurate overprinting during printing, so it is necessary to maximize the accuracy of making up, especially requiring the use of high-power magnifying glass during making up

2) there are many printing times, which is easy to cause poor overprint of small-diameter monofilament (0.25mm) requiring air cooling distance of mm. Generally, overprint inaccuracy rarely occurs when you only dry it once, but not when you print it many times. If you have to print several times, you must use the printing table paper for partition exposure

fake version

ps version does not fit closely with the film photosensitive layer, which will cause fake version Virtual), and the exposed printing plate may have problems such as ghosting and blurring. In this case, you can turn the PS plate at an angle, pad a few sheets of paper under it, and extend the exposure time.

the dot reduction

is generally caused by excessive exposure, high developer concentration, too long development time, and too high development temperature. Take the corresponding treatment methods.

the dot loss and poor field density are generally caused by It is caused by insufficient picture and text density and overexposure of film. The corresponding processing method is to copy the film again and shorten the exposure time

dirty printing

is generally caused by insufficient exposure, insufficient or excessive development, developer failure, film yellowing or fog. The corresponding treatment method is to increase the exposure time, select the appropriate development conditions, replace the new developer or re copy the film

ink

flying ink

ink flies out in a fog between ink rollers. Cause: the viscosity of the ink is too large: the ink is too long and soft; The ink stores static electricity, which is in dry air to avoid rusting and attract different charges

solution: reduce the viscosity of the ink and add an appropriate amount of adhesive remover; Reduce the fluidity of ink; Reduce the printing speed: install Static Eliminators on the printing machine to reduce the impact of static electricity

dirty

the back of the print is dirty by the front ink of the next print, or the ink on the impression cylinder is transferred to the back hd:ha+720 ℃/16h/ac+650 ℃/16h/ac of another print. Cause: the permeability and dryness of the ink are poor, or the curing is too slow; Excessive ink consumption; The paper surface has poor adsorption

solution: improve the permeability, dryness and solidity of ink: appropriately reduce the amount of ink; Choose absorbent paper

paper roughening

in printing, the paper surface bristles when it leaves the blanket

cause: the main reason is that the viscosity of the ink is large, which makes the paper reach or exceed the critical roughening speed. Solution: add thinner or adhesive remover appropriately to reduce the viscosity of the ink

blocking

ink and paper powder are mixed to form ink residue, which is attached to the surface of printing plate, blanket and printed matter

causes: too much ink: the viscosity of the ink is too small or too large, the dispersion of resin and pigment is uneven: the pigment ratio is large: the surface strength of the paper is poor, and the paper powder is easy to fall off

solution: reduce the amount of ink; Adjust the viscosity of the ink properly: change the pigment: control the falling off of the paper powder; Always clean the blockage on the printing plate

powdering

gently wipe the surface of the printed matter, and the ink on it falls down in powder form. Cause: insufficient film-forming agent in the ink: too much powder in the ink and thick ink quality: the ink film is soft but not hard, the dust on the paper surface is large, and the ink absorption is large. Solution: add an appropriate amount of brightening paste containing more film-forming resin and an appropriate amount of desiccant into the ink to speed up the drying of the ink: mix with an appropriate amount of hard ink to polish the printed matter

rubber blanket

plastic deformation of rubber blanket

different pressures on rubber blanket in use will lead to different plastic deformation variables of its thickness, which will lead to uneven thickness of rubber blanket

the greater the pressure, the greater the pressure on the blanket where there is paper, and the more prone to uneven plastic deformation. Therefore, when printing, when the ink can be transferred well, the printing pressure should not be too large, and the best pressure should be used for printing; The tightness of the blanket should be moderate, and the tighter it is. The thinner the adhesive layer of the blanket, the worse the sensitivity and elasticity, and the more prone to uneven plastic deformation; Printing a certain size of paper in large quantities for a long time will lead to large local plastic deformation: after printing for a period of time, the surface of the blanket will adhere to a lot of paper wool and paper powder due to physical adsorption. If it is not cleaned in time, the thick paper wool and paper powder will increase the local printing pressure and cause greater local plastic deformation: when printing cardboard, Under the action of water and ink, the paper scraps produced by cutting at the trailing edge are easy to accumulate in the position outside the pattern edge of the blanket relatively close to the trailing edge of the paperboard. Due to uneven cutting of the paperboard, when printing some slightly longer paperboards, the accumulated paper scraps will cause the depression of the blanket there. Therefore, when printing paper and paperboard that are easy to fall off wool and powder, otherwise there is a risk of electric shock or damage to the machine, the blanket should be cleaned in time: the printing cylinder is adhered with oxidized conjunctive dry ink, and the rubber layout part will be sunken due to uneven local pressure during printing. Therefore, the blanket and the embossing cylinder should be cleaned in time after the printing of products of different specifications and during the shift every day

tightness of the blanket

if the blanket is too loose, the blanket will shift under the action of extrusion pressure and cannot be reset in time during stamping, which will lead to ghosting failure. If the tension is too tight, it will also produce many disadvantages, such as the thinning of the rubber layer and the reduction of elasticity, resulting in uneven printing pressure, affecting the synchronous rolling state, and accelerating the creep and aging of the blanket. For the newly replaced blanket, due to the stress relaxation of the blanket, it should not be too tight at one time. It should be tightened again after pressing and printing for a period of time, and repeated threeorfour times, so that the tightness of the blanket can remain stable for a long time

torsional deformation of blanket

in the stamping process, if the axial positions of the blanket surface are affected by forces of different directions or sizes, the shape of the blanket will be twisted and deformed, resulting in adverse effects on the accuracy of ink transfer overprint and the service life of the blanket. In this regard, first, adjust the axis of the drum to be parallel; second, standardize the operation when installing the blanket, so that the depth of the blanket inserted into the plate clamp is consistent, and all screws for clamping the plate clamp should be tightened

substrate

paper is the basic raw material used in wine box packaging, and its quality directly affects the quality of printed matter. There are obvious differences in the printability of the paper with different characteristics. In the process of printing, the paper characteristics that affect the printing quality include the whiteness, ink absorption, surface smoothness, pH, paper size stability, paper surface strength, etc

the change of the water content of the paper will not only lead to the expansion or contraction of the paper, but also change the local size of the paper due to the change of the water content, and will also produce other forms of deformation, such as curl, wrinkle, etc. For this reason, the paper should be humidified before printing (if there is a gravure machine, it can be dried with the gravure machine). For the paper that has been cut and has large deformation, the curled paper can be folded in the opposite direction, but the force should be appropriate, so that the paper is flat

the higher the number of lines added, the smaller the point, and the small pits on the paper may distort or omit small points. Therefore, for fine prints with a high number of lines, the smoothness of the selected paper should be high. In practical work, we can also adjust some properties of ink or change process parameters to adapt to this characteristic of paper

the influence of the pH value of the paper surface on the gloss of printed matter cannot be ignored. High pH value is conducive to ink drying, which is conducive to improving the gloss of printed matter

printing machine

offset printing is one of the main ways of wine packaging printing. The mainstream printing machines used are mostly Heidelberg Manroland Komori Mitsubishi and other models, with a high degree of intelligence. As long as the operators are familiar with the operation process of the printing machine and the setting of printing process parameters, and basically understand the internal structure of the printing machine, they can print exquisite products. of course. Machine age cannot be ignored. Generally speaking, it is mainly to control the ink balance, printing pressure and printing speed

ink balance is a relative balance, not an absolute balance, during the high-speed operation of the equipment. According to the actual situation, grasp the ink viscosity and the pH value of the fountain solution, and control the amount of ink and water, subject to the printing plate not being pasted and dirty

the printing pressure is too small, the ink is not easy to transfer, and the ink is light and weak; The printing pressure is too high, and the ink expands to the non graphic part, resulting in serious point increase and image distortion. At the same time, it is easy to reduce the printing resistance of the printing plate and blanket. Therefore, the mechanical pressure must be adjusted correctly. Different quantities of paper need different printing pressure. Only the appropriate printing pressure can ensure that the ink color is uniform and the intensity is consistent

printing speed is too fast, which is easy to cause paper peeling, galling and other phenomena. We should consider the performance of the substrate, the size of the substrate, the viscosity of the ink and other comprehensive factors. When printing substrates with large format, large thickness and low surface strength, the printing speed should be smaller; The higher the viscosity of the ink, the lower the printing speed. The printing speed shall be determined to achieve the complete reproduction of pictures and texts and the highest production efficiency

there are still some other problems in actual production, which need further analysis and discussion

Author: chenchangyu

reprinted from: Printing Technology