The article investigates the surface and optical properties of calcium carbonate paper obtained at the UzbekChinese enterprise Fergana stone paper company (Uzbekistan), in order to identify the possibility of their use at printing enterprises for printing multicolor products using traditional printing methods. According to the results of a quantitative assessment of the surface quality by the indirect Beck method, we can say that paper sample 1 has a smoothness like coated paper (750–1500 s), paper samples 2 and 3 – like calendered paper, so that these paper samples can be recommended for prints with increased quality requirements. Smaller values of roughness Ra and small depressions, expressed by darkening in the topographic AFM images, characterized sufficient homogeneity and density of the structure. It was also revealed that the surface of the paper samples has a high ability to specularly reflect the incident light, since the percentage of surface reflection is similar to that of coated papers. Samples of paper have a whiteness of about 90 % and do not have a tint, since the difference between the maximum and minimum values of the reflection coefficients on a white stack is not more than 10 %. The tested paper samples can be recommended without restrictions for double-sided printing, since the opacity index is more than 92 %.

The influence of the sizing agent and filler on the physical-mechanical and surface properties of paper from the cellulose mass of the inner layer of the bark of mulberry tree branches has been studied. According to standard methods, the mechanical strength and absorbency were studied. Surface absorbency for one-side wetting was determined by the method of Cobb(30), by determining the mass of water absorbed by the paper surface when wetting one side of the test sample. It was found that it is advisable to add a sizing agent in the range from 1 to 1.5 g per 100 g of dry cellulose raw materials, since an increase in the additive to 2 g helps to reduce the interfiber bonding forces by 21 %. The addition of 6 g of kaolin affects the distance between the fibers, which reduces the mechanical adhesive forces by 12.5 %. During the analysis of the surface properties of paper samples, the sizing efficiency was found to be from 22.5 to 30 % with an increase in the addition of sizing glue, which can be explained by densification of the structure, which prevents the penetration of aqueous solutions. The addition of 2 to 6 g of kaolin also increases water resistance from 17.5 to 25 %. With the help of a mathematical model, rational values of absorbency were revealed with a composition of 92 %, with a sizing agent of 1.5 g and an amount of filler of 4 g. The resulting mathematical model can be used as the basis for controlling the surface characteristics of paper during its production.

The paper presents the study results of a microgeometry of the paper top made of cellulose obtained from the bark of mulberry tree branches and paper obtained from cotton pulp for comparison. A relationship has been established between the parameters of the technological process of pulp handsheets, in particular calendering, and the surface properties of paper. A study of the surface properties of paper samples was carried out using the direct method of atomic force microscopy, which is universal in the study of surface topography on a nanoscale. Using a Solver HV scanning probe microscope, the microgeometry of the paper top on a nanoscale and a direct image of the profile of the relief changes in topographic images have been examined. It was revealed that the roughness parameters Ra of the surface of a paper sample made of cellulose pulp obtained from the bark of mulberry tree branches after calendering in three frames ranged from 4,86 to 26,34 nm. It was found that the direct method of atomic force microscopy quickly made it possible to obtain surface raggedness parameters on a nanoscale and a direct image of the profile of relief differences in topographic images.

In an article to study the effect of sizing agent and filler on the structural features of paper from the cellulose mass of the inner layer of the bark of mulberry tree branches, mechanical strength, absorbency and sorption properties were studied. Tensile strength was determined on a tensile testing machine by the force causing the destruction of the sample. Surface absorbency at one side wetting was determined by the method of Cobb(30), by determining the mass of water absorbed by the surface of the paper when wetting one side of the test sample. Sorption properties were studied on a high-vacuum setup with mercury gates and McBain quartz balances according to water vapor sorption data. It was found that the internal 2% sizing of the paper pulp with cherry tree resin glue contributes to the strengthening of the paper structure, which is confirmed by the values of mechanical strength and surface absorbency when unilaterally wetted with water, relative to the values obtained when sizing with pine oleoresin rosin glue. When using glue from cherry resin, it is advisable to add 2 g of kaolin to 100 g of pulp from the inner layer of the bark of mulberry tree branches, since the increase negatively affects mechanical strength and hydrophobicity.