engleski

Removal of Ink by Defibration - Colorimetric Properties of Recycled Paper

The removal of roto ink from the newspaper prints by defibration is such a laboratory process, which does not demand the usage of any chemicals, but the ink is washed away by tap water. From the purified fibers, the new paper is produced. The lightness of such paper will be smaller than the lightness of the original paper. This is the most interesting thing for us, i.e. how does the new-formed paper differ from the pure newsprint paper before printing, according to its colorimetric properties? Defibration of the newspaper print has been done in disintegrator. During the process, the greatest particle size of ink has been removed from the fibers, but one smaller part can stay on the new-formed paper and it can give it a certain color. In order to speak about the difference in optical properties of such papers in relation to the properties of the original paper, the lightness degree is not sufficient measure, because it has not been unambiguously defined as such, but it depends on the used expression in calculations. The detailed and complete spectrophotometric analysis will show the differences in hue, lightness and saturation. The defined values for L*, a*, b*, C*ab,  E*ab,  L*ab,  a*,  b*,  C*ab,  H*ab will help in evaluating the optical quality of the recycled paper. In researches, the defined number of daily newspaper of the Croatian editors was used, and for the comparison, the laboratory prints in the defined conditions were used too. Black and colored inks (CMYK), and cyan, magenta and yellow separately were used. By removing the ink by means of the mentioned process, numerous different recycled papers were obtained according to the optical properties. We directed the spectrophotometric analysis to mutual comparison of the real newspaper and laboratory prints as well as to their deviation from the originally pure newsprint paper.

Novinski papir; kolorimetrijska svojstva; tiskovne boje

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