Wine box packaging printing process

In the modern society, people are increasingly pursuing beauty, so the production of exquisite and elegantly shaped wine boxes is very popular among people. However, in actual production, from the design, plate making, printing, post-press processing, to the finished product, almost none of the products can complete these processes flawlessly. Here are some of the common problems in the production process and the corresponding treatment methods, with the majority of peers to discuss.

Plate making

Imprinting is not allowed

1) When imposition, if the position of the graphic or rule lines is not properly matched, it is very difficult to achieve overprinting accuracy during printing. Therefore, it is necessary to maximize the imposition precision, and particularly high-magnifying magnifying glass is required for the imposition.

2) The number of prints is too large and it is easy to cause poor overprinting. In general, when printing only one time, overprinting rarely occurs, but when printing is repeated many times, it is not. If you have to make multiple prints, you must use a printing platen for zone exposure.

Virtual Edition

If the PS version is not closely attached to the photosensitive layer of the film, it will result in a virtual version of the "virtual network", and problems such as ghosting and blurring may occur in the printed plate. In this case, you can turn the PS version to an angle, place a few sheets under it and extend the exposure time.

Dot reduction

Generally, it is caused by excessive exposure, high developer concentration, long development time, and excessive development temperature, and the corresponding processing method can be adopted.

Loss of small outlets, poor density in the field is generally due to the lack of film graphic density, over exposure and so on. The corresponding processing method is to recopy the film and shorten the exposure time.

Dirty print

This is generally due to underexposure, underdeveloped or overdeveloped, developer failure, yellowing of the film, or fogging. The corresponding treatment method is to increase the exposure time, select the appropriate development conditions, replace the new developer or recopy the film.

Ink

Flying ink

The ink flies out of the ink roller. Cause: The viscosity of the ink is too high: the ink is too long and too soft; the ink is stored static and attracts with the opposite charge in the dry air.

Solution: Reduce the viscosity of the ink, add a suitable amount of retreating agent; reduce the fluidity of the ink; reduce the printing speed: install a static eliminator on the printing press to reduce the impact of static electricity.

Sticky

The back of the print is dirty with the front ink of the next print, or the ink on the impression cylinder is transferred to the back of another print. Causes: Infiltration drying of the ink is poor, or the curing is too slow; the amount of ink is too large; the paper surface has poor adsorption.

Solution to improve the ink penetration and drying and coagulation: appropriate to reduce the amount of ink; use strong absorption of paper.

Paper pulling

In printing, the paper fluffs when leaving the blanket.

Causes: The main reason is that the viscosity of the ink is so large that the paper reaches or exceeds the critical pull speed. Solution: Add thinner or remover properly to reduce ink stickiness.

Blocked version

Ink and paper powder are mixed with ink residue and attached to the surface of printing plates, blankets, and prints.

Cause: The amount of ink is too large: the viscosity of the ink is too small or too large, the dispersion of the resin and the pigment is not uniform: the specific gravity of the pigment 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: replace the pigment: control the loss of paper powder; often clean the blockage on the plate.

Powdering

Gently brush the surface of the print, and the ink is powdered. Causes: Insufficient film-forming agent in ink: Too much ink powder and thick ink: The ink film is soft but not strong. The degree of dust on the surface of the paper is large, and the amount of ink is large. Solution: Add a proper amount of bright paste containing more film-forming resin and an appropriate amount of desiccant to the ink to speed up the drying of the ink: Use a proper amount of hard ink to reconcile the print.

Blanket

Plastic deformation of rubber blanket

The pressure applied to the rubber blanket is different, and the plastic deformation of the thickness of the blanket is also different, resulting in uneven thickness of the blanket.

The greater the pressure, the greater the pressure on the blanket at the sheet, and the more likely it is that the plastic deformation is uneven. Therefore, when printing, in the case of good ink transfer, the printing pressure should not be too large, should be the best pressure printing; blanket tightness should be moderate, the more tightly. The thinner the rubber layer of the blanket, the worse the sensitivity and elasticity, the more likely it is that the plastic deformation is not uniform; printing a certain area of ​​paper in large quantities for a long period of time will lead to greater local plastic deformation: after printing for a period of time, the surface of the blanket Because of the physical adsorption, many paper and paper powders are adhered. If they are not cleaned in time, the thick paper and paper powder increase the local printing pressure, and the plastic deformation may occur more locally: When printing the cardboard, The paper scraps resulting from the cutting are likely to accumulate under the action of water and ink at a position outside the edge of the blanket that is relatively close to the edge of the cardboard drag edge. When the slightly longer cardboard is printed due to the uneven cutting of the cardboard, Stacked confetti can cause depressions in the blankets. Therefore, printing is easy to lose hair, powder off the paper, cardboard, the blanket should be cleaned: the impression roller is attached to the drying of the oxide conjunctiva ink, printing will be due to local pressure uneven, causing the rubber layout of the depression, so different When the specifications of the product are printed and the daily shift is over, the blanket and the impression cylinder should be cleaned in time.

The tightness of the blanket

If the blanket is too loosely stretched, the blanket will be displaced under the action of the squeezing force and cannot be reset in time when the blanket is stretched. This may cause ghosting failure. If it is stretched too tightly, it will also have many drawbacks, such as thinning of the rubber layer and reduced elasticity, resulting in uneven printing pressure, affecting the state of simultaneous rolling, and accelerating the creep and aging of the blanket. For the newly replaced blanket, due to the stress relaxation phenomenon of the blanket, it cannot be stretched too tightly at one time. It should be tightened again after printing for a period of time. After repeated three or four times, the tightness of the blanket can be made longer. The time is stable.

Torsional deformation of blanket

During the imprinting process, if the axial direction of the blanket surface is affected by different directions or different forces, the shape of the blanket will be torsionally deformed, resulting in the transfer of overprinting accuracy of the graphic shape ink and the use of the blanket. The adverse effects such as life expectancy. In this regard, one is to adjust the axis of the drum parallel: the second is to standardize the operation when the blanket is installed, so that the depth of the blanket inserted into the plate is the same, and all the screws clamping the plate clamp are tightened.

Substrate

Paper is the basic raw material used in the packaging of wine boxes. The quality of the paper directly affects the quality of the printed matter. The characteristics of the paper used are different, and there is a clear difference in printability. In the printing process, the characteristics of the paper that affect the printing quality include the whiteness of the paper, the smoothness of the ink-absorbing surface, the stability of the pH and paper size, and the strength of the paper surface.

Changes in the moisture content of the paper not only lead to the expansion or contraction of the paper, but also due to the change in the moisture content that causes the local size of the paper to change, as well as other forms of deformation, such as curling, wrinkling, etc. For this purpose, the paper should be subjected to humidity conditioning before printing (if gravure printing machine is used, it can be dried by gravure printing machine). For paper that has been cut and deformed, the curled paper can be folded in the opposite direction, but the force should be appropriate to achieve a flat paper.

The higher the number of screens, the smaller the number of dots, and the tiny pits on the paper that may distort or miss tiny dots. Therefore, for fine prints with a higher number of screens, the smoothness of the selected paper is higher. In practice, this characteristic of the paper can also be adapted by appropriately adjusting some properties of the ink or changing the process parameters.

The effect of the paper surface pH on the gloss of the printed matter must not be overlooked. The high pH value is good for the drying of the ink, which helps to improve the gloss of the print.

Printing machine

Offset printing is one of the main methods for wine packaging printing. The mainstream printing presses used are Heidelberg Manroland Komori Mitsubishi and other models, which have a high degree of intelligence. As long as the operators are familiar with the operation flow of printing presses and the setting of printing process parameters, Basically understand the internal structure of the printing press, you can print a beautiful product. of course. Age can not be ignored. In general, it mainly controls the balance of ink and ink, printing pressure, and printing speed.

The ink balance is a relative balance, not an absolute balance during the high-speed operation of the equipment. Should be based on the actual situation, grasp the ink viscosity and the pH of the fountain solution, control the amount of ink and the amount of water to the plate does not paste version is not dirty version prevail.

Printing pressure is too small, ink is not easy to transmit, ink is light and weak; printing pressure is too large, ink is extended to non-graphical parts, making the dot gain serious, image distortion, but also easy to make printing plate and blanket resistance . Therefore, the mechanical pressure must be properly adjusted. Different quantitative papers require different printing pressures, and only proper printing pressure can ensure uniform ink and uniform shades.

Excessive printing speed can easily lead to peeling and pulling. Should consider the performance of the substrate, the size of the substrate, the viscosity of the ink and other comprehensive factors. When the printing medium is large, thick, and has a low surface strength, the printing speed is smaller; the greater the viscosity of the ink, the lower the printing speed. The determination of printing speed is based on the complete reproduction of graphics and the highest production efficiency.

In the actual production, there are still some other problems that will arise and we need to further analyze and discuss.

Author: Chen Chang Yu

Reprinted from: Printing Technology