1. Smoothness and gloss of paper
From the impact on the quality of printed matter, there is a very direct relationship between the gloss of paper and the gloss of printed matter, no matter what type of ink, the gloss of printed matter is increased with the gloss of the paper itself. The gloss of the paper is directly related to the inking efficiency of the paper, and the paper with high gloss can obtain higher printing density than the paper with low gloss at the same ink film thickness on the paper. Therefore, there is a close correlation between the gloss of the printed matter and the gloss of the paper itself.
2. Ink acceptance and absorption properties of paper
Ink acceptance refers to the ability of the paper surface to receive transfer ink instantaneously during the printing process. It is closely related to three aspects of paper performance: the ability of the paper surface to accept printing ink wetting; The ability of the paper surface to absorb certain ink components; The ability of paper surfaces to hold and retain uniform ink film. The paper's ink absorption performance occurs in a longer period of time from ink to paper contact to complete curing on paper, which is related to the absorption of low-viscosity components in ink by paper pores and the penetration of some components in ink into the paper. Printing pressure, printing time, ink viscosity, paper capillary radius will affect the paper's ability to absorb ink. When the same ink is printed on paper with different absorbency under the same conditions, there will be different printing densities. There are pore structures formed by anisotropic polyphase complex structural elements on the surface of the paper. In order to obtain good uniformity and smoothness on the paper surface, coatings of different thicknesses are generally applied on the surface of the paper. The properties and thickness of the coating determine the ability of the paper surface to absorb ink. The different absorption capacity leads to the difference in the color of the printing ink layer.
3. Paper whiteness
The factors that affect the whiteness of paper are:
The whiteness of the paste: the most important influencing factor.
② Dye: The selection of dye should be so that it does not affect its reflectivity near the main wavelength of the measurement of whiteness, that is, it does not affect the whiteness of the paper.
③ Filler: depends on its type and grade.
④ Paint: the whiteness of paint printing paper is determined by the whiteness of base paper, the whiteness of paint and the amount of coating. Different whiteness and paper with a certain color (such as some paper is blue and the latter is yellow) have different effects on the color of the printing ink layer. For the same kind of white board paper, the whiteness is different, especially for the color with a higher brightness value, the impact is particularly obvious, resulting in a great difference in the ratio of spot color ink. Therefore, in actual production, paper with the same whiteness should be printed as far as possible to reduce the impact of paper whiteness on printing color.
