Establishment And Application Of Method On The Analysis Of Surface Pores On Paper

With the rapid development of science and technology, people’s request for the quality and performance of the paper have become increasingly high demanding. Many properties of paper such as ink absorption, printing and filtration performance get affected by its porous structure. So far, the majority of methods to test the surface pore of papers remain using the traditional ways, which was very time-consuming, only a few using automatic pore analyzer, which was quite expensive. Therefore establishing a rapid simple and low cost method of surface pore analysis for paper is particularly significant to evaluate structure and properties of paper.This paper established such a method based on image processing technology. Using IPP(Image-Pro Plus) image software to analysis and pretreat SEM image and combined with the analysis test of GUI(graphical user interface) designed by Matlab, finally got the pore property of paper and compared to IPP to verify the reliability of this method and found its optimization conditions. The results show that the best color intensity was 90; the best interval of brightness, contrast and gamma correction were 45%-50%, 50%-55%, 0.9-1.0, moreover, the opening morphology of the filter processing was relatively optimal.Established the method of surface pore analysis of paper through GUI set up by Matlab. The results reveal that the optimal threshold of GUI was 80, moreover, the error and the relative standard deviation of porosity results was only 0.8% and 3.48%, which performed its high reliability and precision. The relative standard deviation of the number and area of pores was 1.73%、3.58%, which may be represented as pore property parameters of paper.Studied the pore property of coated paper based on the established method and printing performance. The results show that the surface pores are mainly small diameter of 1-20μm, improving the compactness of base paper can reduce coating porosity and pore size distribution interval, increase the regularity and the number of pores. When the porosity between 10%-12% and pore size distribution with wide range(1-50μm), the printing surface strength was low and the color difference was very close; when the porosity was less than 10% and pore size distributinon located in 1-30μm, the printing surface strength was basically unchanged, but its color difference increased with the porosity of coating surface was larger.The pore property of filter paper surface and filter performance are also studied. Contrary to coated paper, the number of pores mainly on 1-20μm interval and the area mainly on more than 20μm. The permeability and the porosity of handsheets was up to 88320ml/min and 32.27%, the maximum aperture was close to 90μm. Improving tightness of filter paper can reduce the porosity and pore size distribution, while decreased the permeability; moreover, the filtration efficiency was not only related to porosity, but affected by pores interval and its number, and reducing the porosity and pore size distribution can significantly improve the filter efficiency.