Analysis of Corrugated Cardboard Offset Preprinting Technology (Part One)

In order to make products appeal to everyone's eyes and stimulate people's desire to buy, corrugated cartons have been designed as more and more attractive, and offset preprinted corrugated boxes are one of the most important means of achieving these beautiful designs.

Offset preprinted corrugated box technology is to use corrugated cardboard production line to produce single-faced corrugated cardboard. At the same time, it performs fine-colored halftone offset printing on the surface of the surface paper, then pastes the face paper with adhesive to single-faced corrugated cardboard, and finally Cutting/grooving, sticking boxes, and nail boxes complete the forming of corrugated boxes.

However, there are also many weaknesses in this printing process. Therefore, other printing processes have developed rapidly and have surpassed them and replaced them. Then, what are the disadvantages of offset printing and how to overcome them in the actual production operation, so as to cope with the competition of various printing technologies in the market? In this regard, we interviewed several professionals of packaging and printing companies that used corrugated preprinting to produce corrugated cartons. They were Mr. Wang Guoping, the head of operations of Wuhan Huaheng Color Top Packing Co., Ltd., and Wang Dongjing, the chief engineer of Baoding Xingliang Printing Factory. Mr. Feng Fengyuan of the Langfang 1206 Printing Plant and Mr. Li Jun, a welfare paper product factory in Chaoyang District, Beijing, hoped that the problems and solutions they encountered in the actual production process could provide reference and help for everyone.

First, the carton design should pay attention to the problem

When printing corrugated cardboard paper with offset printing, it often appears that the carton size does not meet the requirements due to improper packaging design and process design, ghosting, printing and printing silver effect is not good, easy paste version, scratches, printing products dull, ink Uneven layer thickness, light weight before and after the problem.

During the interview, everyone put forward the following requirements for corrugated box design and process design:

(1) When designing a carton, the thickness of the corrugated board used must be taken into account. The size of the finished product given to the general customer is the internal size, and the external size should be determined based on the material and thickness of the corrugated board used.
(2) layout text can not be too fine. The main function of the exquisite corrugated box is to highlight the effect of propaganda, and the graphics and fonts should not be too small, otherwise it will not achieve the effect of propaganda. Words less than 2cm in length are generally not visible at a distance of 5m, thus losing the significance of publicity and sales.
(3) It cannot be designed as a four-color large-area flat-screen overlay because corrugated cardboard is used with 250g/m2 gray-end whiteboard paper. The texture of this paper is relatively poor, and it is easily deformed, dregs, and powdered when printed.
(4) Consider the color sequence when designing. If the color sequence is improper, the printing effect will not be good.
(5) Gold and silver ink should be placed on the final seal. When printing gold and silver backgrounds, if there are patterns or text above, gold and silver should be printed first, otherwise they will go back.

Second, problems related to printing equipment

Printing equipment

Printing equipment has the most direct impact on the printing quality of corrugated cardboard paper, and the effects of different equipment are also different. The domestic offset presses used for corrugated cardboard printing are basically imported used equipment (such as Heidelberg, Manroland, etc.) and domestically produced high-quality equipment.

Imported used equipment may have problems more or less for a long time, such as machine vibration, slow speed of the machine, inaccurate overprinting, and ink bars. Wuhan Huaheng Color Top Packing Co., Ltd. has two second-hand manroland offset presses for printing corrugated cardboard paper. The above problems have arisen in production. Mr. Wang Guoping was very frustrated with the problems of second-hand equipment because Wuhan Huaheng Color High-grade Packaging Co., Ltd.'s main business is Budweiser packaging. The customer's quality requirements are extremely stringent. Domestic high-end equipment is quite Yes, but the overall printing effect is worse than that of foreign equipment. If you purchase imported new equipment, the investment is quite large. A new Heidelberg offset press will cost about 20 million yuan. Therefore, these problems can only be avoided as much as possible. Once a certain problem arises, improvement is targeted, but it cannot be improved in advance.

The equipment-related failures that have occurred during the printing process in Langfang 1206 printing factory mainly include: overprinting is inaccurate, the color difference is poor, and the ink sticks are used, causing prints to produce flowers, discoloration, ghosting, lint, and peeling. Such phenomena. First-line production personnel solve the above problems by adjusting machines, replacing paper, adjusting pressure and water supply.

For overprinting, Mr. Wang Dongjing, the chief engineer of Baoding Xingliang Printing Plant, recommends using a four-color offset press to print corrugated cardboard paper. This can be done at one time, avoiding the impact of overprint and deformation on paper overprinting.

Unresolved issues: The monochrome ink offset press is full of ink, but it is prone to overprinting; the four-color offset press is accurate, but the amount of dust required is high and the problem of insufficient ink is difficult to solve. For the problems that cannot be overcome by the device itself, different models can only be selected as needed.

2. Ink

First, corrugated box printing is also very picky for inks. The hiding power of ink is stronger and the color should be brighter. Because the color of the corrugated paperboard itself is quite dark, when selecting the printing color, inks with large color saturation and strong coloring power (such as large red) should be used as far as possible, otherwise there will be a big gap between the printed colors and the desired colors.

Second, the viscosity of the ink should be appropriate. If the viscosity of the ink is too high, and the quality of the paper is not good, sticking and fluffing may occur. At this time, it is necessary to add a certain amount of varnish dilution before release.

Wuhan Huaheng Color High-end Packaging Co., Ltd. is generally based on the requirements of different customers choose different inks. Printing Budweiser series beer packaging boxes mainly use Mudan brand ink, which is of good quality. In addition, the company has its own set of quality inspection system, inspects raw materials before they are put into storage. If the quality of raw materials does not meet the requirements, they will not be able to be returned to the supplier directly. The company once had problems with ink and paper adhesion, and it used a method of requiring suppliers to replace it. Otherwise, the company would look for other brand suppliers. In short, it is based on the principle of meeting the needs of customers.

Summarizing all the other ink-related problems that all respondents interviewed in the printing of glossy papers are: ink is too thick or too thin, inks are printed and dirty; inks are dried too quickly or too slowly, and drying is too fast to cause color changes. Drying too slowly can cause dirt. The solution is: instead of using good-quality inks, that is, do not dry on the plate cylinder, dry ink on the paper, or add the varnish and additives.

Unresolved issues: I hope there will be some kind of technology or a company that can improve the heavy metal content of inks.

3. Paper

Corrugated cardboard should meet the requirements of smooth surface, no dirty spots or fluffing, accurate cutting size, and vertical four corners.

At present, corrugated paperboard paper is mainly made of domestic paper. There are many problems with domestic paper, mainly including:

(1) Paper powder is more.
(2) The paper is uneven and flat.
(3) The moisture content of the paper does not meet the normal requirements, either too high or too low. The standard moisture content of paper is about 7%, but the water content of the paper produced by the southern and northern manufacturers is not the same. The paper produced by the southern manufacturers has a high moisture content, and the paper produced by the northern manufacturers has a low moisture content. All of these factors make the printed glossy paper not reach the expected printing effect, which greatly reduces the advantages of offset printing and fine printing.
The corresponding solution is as follows:

(1) When printing, put a flannel on the plane where the machine's paper feed is in contact with the paper, and remove some of the paper dust like a broom.

(2) If there is unevenness in the paper, suppliers should be found to solve it. If the quality of paper does not meet the requirements, it cannot be stored in the warehouse, not to be on the production line.

(3) The moisture content of the paper is too low and it can be stored for a few days so that it can slowly absorb moisture, but the water content is too high to be returned.

In addition, when printing corrugated cardboard, it is necessary to pay attention to the texture of the paper. If it is a longitudinal corrugated cardboard, horizontal cross-filament paper is used, while cross-hatched corrugated paper is used to twist the paper, so that the corrugated cardboard is flat and straight. .

Unresolved issues: Domestic paper is not as good as imported paper. There are problems of one kind or another, and the price of imported paper is too high.

(to be continued)