Analysis on the influencing factors of the printin

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Abstract: with the continuous growth of China's economy, China's packaging carton and carton industry has developed rapidly. Packaging whiteboard has gradually replaced yellow board, and developed from monochrome printing to white background color printing. Higher and higher printing requirements are put forward for packaging carton. This paper discusses the factors affecting the printing quality of white board

key words: white cardboard; Printing quality; Printability

white paperboard is divided into double-sided white paperboard and single-sided white paperboard. Double sided white paperboard is mainly used for the packaging of high-end goods, while general cartons and cartons mostly use single-sided white paperboard, such as the outer packaging boxes for cigarettes, cosmetics, drugs, food, stationery and other goods

with the rapid development of China's economy, the social demand for packaging color boxes and cartons is increasing, and the requirements for printing quality are also higher and higher. Its printing development trend is reflected in three aspects: first, carton transportation packaging is gradually developing to commodity packaging, and the printed words and patterns of packaging cartons are required to be clear, beautiful, bright, multi-color, dot, and three-dimensional; Second, the printing of packaging cartons and cartons will gradually develop from monochrome and two-color printing to multi-color printing such as three-color and six color printing, which requires accurate chromatic registration, and the point will develop from the current 150 lines/cm to 200 lines/cm. At the same time, the precision of packaging and printing machinery is required to be quite high; Third, packaging white paperboard will gradually replace yellow paperboard, develop white background color printing, and replace solvent ink with water-based ink, so as to make the printing surface of packaging cartons and cartons beautiful, clear and bright, with high content of printing technology, improve the added value of goods, and meet the requirements of environmental protection. In white board printing, transparent plastic film is often used to replace glass substrate. There are two printing methods: offset lithography and flexographic printing. Exquisite high-grade cartons and cartons are required to adopt offset printing, while general cartons and cartons mostly adopt flexographic printing, and their quality requirements should meet the industry standards of relevant printing methods. This paper discusses the main factors affecting the printing quality of white board

1 brightness of paperboard

whiteness of paperboard refers to the whiteness of paperboard, which is the total reflection of uniform diffuse reflection of visible light in all wavelength ranges. The factors that affect the whiteness are mainly the lignin content and bleaching degree in the paper paddle. Because lignin has chromogenic groups, in order to obtain high whiteness paper, it is necessary to minimize the lignin content in the paper. The whiteness of the white paperboard has a great impact on the color range of the final printed matter. The higher the whiteness of the paper, the more it can reproduce the true color of the ink. The final printed matter will be reduced year by year in three stages in the future. The more bright the color reproduced and the wider the color gamut displayed. Now suppose a field red is printed on the white board, first yellow and then magenta. There is not only a large amount of small and medium-sized enterprise transaction data, as shown in the following figure 1. The actual red (R) is formed by laminating the yellow (y) ink layer and magenta (m) ink layer printed on the white paperboard. The white light (W) first absorbs the green light (g) in the white light through the magenta ink layer on the upper layer, and then irradiates on the yellow ink layer to absorb the blue light (b) in the red light and blue light. In this way, only the red light irradiates on the white paperboard, which is reflected by the white paperboard, then passes through the Y and M ink layers, and filters out the blue light and green light again to make the red more pure, However, if the whiteness of the whiteboard is not high, the amount of red light reflected on it is less, and the final red light emitted is also less, reducing the color saturation of red. Packaging color

in carton printing, color is a very important quality index, and customers are also highly sensitive to it

in addition, the printed image generally cannot be printed in 3% to 5% of the bright tone area and more than 95% of the dark tone area, that is, the highlight part of the printed matter is formed by the color of the paper. If the whiteness of white paperboard is different, it will affect the color brightness and saturation of the brightness adjustment of the picture, and then affect the color contrast of the picture

2 gloss of white paperboard

gloss is the closeness of the paperboard surface to the full specular reflectance in terms of the ability to reflect incident light. It is expressed by the ratio of the specular reflectance of paperboard at a certain angle to that of standard black glass at the same angle. When the gloss of paper is large, the color of its printed matter appears more bright

a very obvious feature of color box printing is that the printing is bright and full. In order to make the printing color bright, the gloss of paperboard is an index that must be considered. The higher the light permeability of paperboard, the stronger the reflection ability of light, the brighter the color

3 smoothness of paperboard surface

generally speaking, smoothness refers to the calibration time of the speed required for a certain volume of air to pass through the gap between the sample surface and the glass surface under a certain pressure and a certain area under a certain vacuum, expressed in seconds. The smoothness of paperboard surface has a direct impact on printing. Paperboard with high smoothness is easy to be evenly covered by ink film during printing. The paper with higher smoothness can be used for more detailed and precise printing points to produce higher quality prints. On the contrary, when printing on the surface of paperboard with low smoothness, in order to ensure the transferred ink layer, the printing pressure must be increased, resulting in the expansion of printing points and the loss of fine levels of graphics and texts; In addition, one of the characteristics of the development of color carton printing is that the number of lines is getting higher and higher, gradually developing from the original 150 lines/cm to 200 lines/cm, and the requirements for point level reproduction are getting higher and higher

in printing, we first require that the smoothness of the white board used is uniform to ensure that the expansion of the printing point is within the allowable range. For general offset lithography products, the 50% point expansion value of yellow ink (y), magenta ink (m), green ink (c) and black ink (BK) is controlled at 10% - 25%, and for fine products, y and m are controlled at 8% - 20%, C is controlled at 10% - 20%, and BK is controlled at 10% - 25%, Flexographic printing 70% point expansion Paper Science & Technology 2005 Vo1.24 No.3 value is less than 21%. The second is cardboard with high smoothness

(to be continued)

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