Infrared spectrophotometry was applied to analyze the coated materials (binder and clay) of claycoated papers, using the reflection method and the transmittance method.
The reflection method was carried out mainly by using the technique of ATR (Attenuated Total Reflection) with the instrument of CIC. The results showed that absorption of clay was too strong to distinguish that of binders. Therefore it was possible to identify coated clay, but the scope of application was found to be limited to a single kind of clay. That is, characteristic absorption bands were overlapped in more than a single kind of clay.
The transmittance method was applied, using the peeled off coated layer as sample. As well as in the case of ATR, this method made it possible to identify the kind of clay, but it was impossible to do so about binders. If binders are isolated from coated layers into each composition by the extraction method, however, the transmittance method made it possible to identify some kinds of binder.
In addition, some analytical data obtained about commercial coated papers are shown.