Whiteboard with gray background and white cardboard have similar application fields in food, cosmetics, gifts, medicine packaging and so on. However, what is the difference in surface properties between the two kinds of paper? And do these differences have any influence on the reproduction effect of the printing tones of the two kinds of paper, and to what extent? In this paper, the surface properties and color reproduction of these two kinds of packaging paper are compared and studied, and the efficiency difference between them and their respective color reproduction efficiency are compared and analyzed, which provides useful data reference for quantitative analysis of the efficiency of these two kinds of paper and better utilization of these two kinds of paper. 1 experiment Based on the difference of the surface properties of the two kinds of packaging paper, the basic surface properties of each sample of the two kinds of paper were determined by experiments. Then, according to the basic surface properties of each pattern, select certain printing conditions, print and sample on IGT printability instrument, find the best ink layer thickness of each pattern, and print and sample under their respective best ink layer thickness; Finally, the dot area ratio and field density of each paper sample were tested, and the samples were analyzed, and the differences between the two kinds of wrapping paper and their effects on the hierarchical reproduction efficiency of printed matter were compared and studied. Experimental materials: Changxing white board 250g/m, Huaming white board 250g/m, Huafeng white board 250g/m, Hongze white board 250g/m, Fannan white board 250g/m, Asia-Pacific white board 250g/m, Sun white board 250g/m, Holland white board 250g/m. The inks used are yellow, magenta, cyan 1. 1 the experimental instrument for testing the surface properties of paper: WSB-II whiteness meter; UGV-50 variable gloss meter angle change gloss meter; YM-20 ink absorbency tester; Model M590PAKERPRINT-—SURF surface roughness tester. Experimental environment: temperature 265438 0℃, relative humidity 49 ~ 565438 0. Through experiments, the performance data of eight modes are shown in table 1. 1.2 to determine the best ink layer thickness, printing proofing experimental instruments, printing conditions and experimental environment: IGT printability instruments Aich2-5, 65L/ ear anilox roller and X-Rite 528 densitometer; Pressure 650N, printing speed 0.2 m/s; The temperature is 2l℃ ~ 25℃ and the relative humidity is 45 ~ 55. Through a lot of printing proofing and testing, the optimum ink layer thickness of each paper pattern is found, as shown in Table 2.
Then, according to the optimum ink layer thickness of each paper and the above printing conditions, the yellow, magenta and cyan screen samples of eight paper samples were printed with the same ink on the AIC2-5 IGT printability tester. After measuring the screen color block and real color block with different dot area ratio of each sample, the dot gain curve, printing characteristic curve and gray density contrast curve of three colors of eight paper samples are obtained. 2. Comparative Analysis of Gray Reproducibility between Grey-based Whiteboard Paper and White Cardboard Paper 2. Comparative Analysis of Dot Increase Value: Take the contrast of dot increase of Tu Tu 1 Magenta Ink as an example.
For example, it can be seen that the dot enlargement of the gray bottom of the whiteboard pen is larger than that of the whiteboard pen. Among the factors that affect the dot gain of printed matter, as far as paper is concerned, the absorbency and roughness of paper have a great influence on the reproduction of tone. These two arguments are often closely related to printing pressure. In this study, the printing pressure is a certain value, so the difference between paper absorbency and roughness reflects its influence on tone reproduction. From the previous test data of paper surface performance, there are still obvious differences in water absorption and roughness between gray-based whiteboard and white cardboard. White board has higher absorbability and lower roughness than gray whiteboard. Dutch white cardboard is imported cardboard, but the manufacturing process is different. The higher water absorption of paper may lead to the increase of dots, while the lower roughness will make the surface deformation of paper less under the action of printing pressure, and the required ink film is thinner, which is more conducive to reducing the increase of dots. Therefore, basically, it can be considered that gray-based whiteboard paper is worse than white cardboard in tone reproduction. 2.2 Comparative analysis of printing characteristic curve Tu Tu 2 of each paper sample using magenta ink.
Through the example analysis, it can be seen that the printing characteristic curve of white paperboard is basically below the gray-based white paperboard, which shows that the gray density error of white paperboard is relatively small. It can be seen that the color reproduction efficiency of white paperboard is better than that of gray paperboard. 2.3 Contrast Analysis of Tone Density Another method to evaluate the tone reproduction of printed matter is to evaluate the tone density contrast of printed matter. When it has a higher printing relative contrast value, its true density is higher, and the tone reproducibility of printed matter is better. Similarly, taking the gray density comparison of the magenta ink sample shown in Figure 3 as an example,
As can be seen from the figure, except Dutch white cardboard, the relative contrast values and corresponding field density values of Asia-Pacific white cardboard and Sun white cardboard are higher than other kinds of gray-based white cardboard in different degrees, except Dutch white cardboard. This shows that the color reproduction efficiency of white paperboard is relatively better than that of gray paperboard. The research and analysis from the above three different angles show that white paperboard has better color reproduction efficiency than gray paperboard. However, in the research and analysis of these three different angles, Dutch white cardboard is an exception, which is even worse than the worst gray-based white cardboard in terms of relative contrast, field density, dot gain and tone restoration. After consulting relevant information, we know that Dutch white cardboard is a common white cardboard, which is different from the above-mentioned Asia-Pacific white cardboard and Sun white cardboard. Asia-Pacific white cardboard and Sun white cardboard belong to a kind of white cardboard commonly known as "copper white card". On the basis of ordinary white cardboard, this kind of white cardboard has higher surface properties similar to coated paper, such as smoothness and gloss, through sizing, coating and calendering. It is precisely because Dutch white cardboard has lower surface properties such as smoothness and gloss than ordinary gray-based white cardboard, so the color reproduction efficiency of Dutch white cardboard is relatively poor. However, because Dutch white cardboard does not have similar application fields as other copper white cardboard, as an exception, the special situation of Dutch white cardboard will not affect the research conclusion of this experiment. Conclusion There is a great difference in surface properties between gray-based whiteboard and white cardboard, especially in whiteness and surface efficiency. The gray-based whiteboard is obviously inferior to the corresponding quality grade of white cardboard. The surface properties of gray-based white cardboard and white cardboard have great influence on the color reproduction of printed matter. Under the corresponding quality level, the color reproduction effect of white cardboard is better than that of gray-based white cardboard.