Analysis of printing characteristics of matt coated paper
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Matte coated paper, also known as matt coated paper or matte paper, is mainly used for the production of high-end books, commercials, listings, albums, children's books, travel brochures, atlases, covers and other printed matter. Matte coated paper has low gloss and is not dazzling. The printed pattern has brighter color, strong stereoscopic effect, and the text part also has good reading comfort, so it is favored by consumers. According to relevant information, the consumption of European matt coated paper accounts for 40% to 50% of the total consumption of coated paper, and it has a trend of increasing year by year. The proportion of matt coated paper in China is relatively small, mainly because of consumer awareness and The production technology determines, but the amount of matt coated paper will gradually increase with its unique advantages.
In this paper, three kinds of domestic matt coated paper and two imported matt coated papers were selected for experimental test analysis, and the printing density, dot reduction, gloss, printing contrast, and three-color overprinting rate of matt coated paper were obtained. The superiority of optical coated paper in high-end printing production provides data reference for actual printing production.
First, the experiment
1. Materials and equipment
MATERIALS: Three kinds of 128 g matte coated papers produced by Jindong Paper (Jiangsu) Co., Ltd. were expressed as Pattern 1, Pattern 2 and Pattern 3. Nippon Paper Industries Co., Ltd. (NPI) and 128 g of matt coated paper produced by Maolin Paper of Korea, expressed as pattern 4 and pattern 5
Equipment: Komori LS-540 printing machine; X-Rite528 spectrodensitometer; KGZ gloss meter;
2. Pattern printing and testing
Printing conditions, ambient temperature: 25 ° C; ambient relative humidity: 58%; printing plate: Fuji Xingguang CTP plate; printing machine: Komori LS-540 printing machine, printing color sequence: K-C-M-Y. The printing pressure is 0.13 mm. Ink: Tianjin Toyo Ink.
Qualified samples are randomly selected from qualified prints. The printed matter was tested on a black background using an X-Rite 528 spectrodensitometer. The instrument parameters were set: the dot area test used T response mode, the dot area calculation formula: Murray-Davies; the print contrast measurement data was subtracted from the paper value, and the response was E mode; the calculation formula of the overprint ratio is the Beres (GATF) overprint formula, the overprint rate and the gray scale error measurement source are D50, 2° field of view, and the response mode is E mode. Gloss measurement is performed using a 60° lens.
data processing. The sample mean formula, namely: the same mean value in the formula; n-sampled samples; i-sample order; xi-extracted sample individuals.
Second, the results and analysis
1. Field density
Table 1 shows the mean density of solid printing on matte coated paper. Although the smoothness of matt coated paper is much lower than that of glossy coated paper, it can be seen from Table 1 that the printing density of matt coated paper is close to that of glossy coated paper, so it can be expressed with a glossy copper plate. The same print tone of paper. However, the matte coated paper has a large surface roughness, and a larger ink supply amount is required to produce a sufficient ink layer thickness to achieve the same printing density as compared with the glossy coated paper.
2. Network reduction
The expansion of outlets is affected by many factors, such as printing pressure, ink, and paper properties. Figure 1 shows Figure 1, which can be obtained from Figure 1. The network expansion data is basically the same as the whole. Only the yellow version of the intermediate adjustment network has an expansion value of 18%, which is slightly higher, which may be higher than the printing density of the yellow plate. related. Since the matte coated paper has a low smoothness and a high surface roughness and ink absorbing property, a large amount of ink and printing pressure are required in the printing process as compared with the glossy coated paper.
3. Printing gloss
The gloss of the print depends mainly on the gloss of the paper. As can be seen from Table 3, the difference between the gloss of the paper and the gloss of the print is not large, and the print gloss of the sample 4 and the sample 5 is even lower than the gloss of the paper. This is mainly because the ink is affected by the surface roughness of the paper during the process of leveling and drying of the paper surface. During the drying process, the surface of the ink layer is also uneven, and a smooth and transparent ink film is not completely formed. A small amount of light is caused by specular reflection on the surface of the ink layer.
The printing quality of matt coated paper is generally considered to be a large difference between paper gloss and printing gloss. The difference between paper gloss and printing gloss is generally around 30-40. This value is based on QB1020- Under the conditions of the black standard bright ink specified in the 1991 standard, the ordinary ink used in actual production does not have such a large difference. Therefore, the visually bright representation of the printed area of the matte coated paper can be thought of as a small amount of specular reflection on the surface of the ink layer. Therefore, in the printing production process of matt coated paper, in order to make the printing area show a certain luster, it is preferable to use bright light fast drying ink and ensure the ink supply amount to generate sufficient ink layer thickness.
4. Print contrast
Print contrast, also known as K-value, is an important indicator of the degree of detail retention in printed images. The higher print contrast ensures a clear print and guarantees the detail reproduction of the dark areas. To achieve a high print contrast requires a high density in the field, while ensuring that the printing effect is clear to preserve the details of the dark area. As can be seen from the data in Table 4, the printing contrast of matt coated paper exceeds the typical printing contrast of single offset printing (commercial printing), so matt coated paper can achieve higher printing density and can The important details carried in the dark areas of the printed image are well represented and highlight the high-quality side of the printed pattern.
5.RGB three-color overprint rate
Overprinting is an important reflection of the printing color sequence, which indicates the ability of the ink to adhere to the paper and attach to another ink. If the overprinting is bad, the color deviation and level of the product will be disordered. The overprinting rate is affected by the thickness of the ink layer of the ink, the printing color sequence, the printing pressure, the viscosity of the ink, the interval between the printing, and the like. The higher the overprint ratio, the better the overprinting effect. As can be seen from Table 5, the overprinting effect of matt coated paper is not particularly good, and can only barely approach the requirements of typical commercial sheetfed offset printing, mainly because the surface of matt coated paper is rough, printing pressure and ink delivered. The amount of ink is large, the viscosity of the ink is improper, and the ink layer of the overprinted ink is insufficiently fixed and dried. Therefore, in the printing process of matt coated paper, attention should be paid to adjusting the printing pressure, ink viscosity and printing speed to prevent the overprinting rate from decreasing and affecting the printing quality.
Third, the conclusion
Through this experiment, it can be obtained that due to the matt characteristics of the matte coated paper surface, the paper surface is not reflective, so that the printed image is clear, the printing contrast is strong, and the reading is comfortable and the texture is elegant. Matte coated paper has good dot reduction and high printing contrast. The gloss of matt coated paper before and after printing does not change much, but the matt effect of matte coated paper and printed graphics are visual products. The bright performance is still contrasted, highlighting the printed pattern. Therefore, matt coated paper is particularly suitable for high-end printing such as commercial advertisements and albums.