The X-ray diffractometry was applied to examination of kinds of pigment and absolute weight of respective pigments for manually-coated papers and commercial coated papers. The authors proposed in the previous paper the method of quantifying weight ratio of pigments in the coating. However, the application of the method was confined to the basesheet containing known amount of filler of the same kind. Then, the new method of preparation for the X-ray diffraction sample without information about basesheet was established. This method also makes is possible to eliminate the influence of the kaolin pigments orientation. Moreover, it has an advantage of distinguishing the crystal forms.
The process of sample preparation is as follows. First a coated paper sample was fixed on a polyethylene film by a 2-sided adhesive tape or agent with the coating surface adhered to the film. Next, the sample was immersed in a cupric ethylenediamine solution for one day to swell and dissolve the fibers. After washing with a calcium carbonate saturated solution, it was carbonized at 280°C. An appropriate quantity of KBr was added to the powdered sample as an internal standard. The mixed sample was submitted to X-ray diffraction.
The following is the results obtained.
1. The weight of pigments of manually-coated papers was determined by X-ray diffractometry. The obtained values were almost same as those by gravimetric method.
2. The ratios of respective pigments of commercial coated papers are almost equal to those measured by X-ray microanalysis which is a conventional technique for quantitative analysis.