Method of determining type of plastics.

摘要

The method of the present invention comprises the steps of irradiating near-infrated rays to a plastics of an unknown type to measure the NIR spectrum thereof, determining the first-derivative or second-derivative, measuring the differential spectrum at prescribed intervals of wavelength over a region of measurement wavelengths, determining the class of whether the differential spectrum for each measurement wavelength is on the plus-side, minus-side or any other side, comparing the resultant class data with those of previously determined differential spectra for plastics of known types to determine the ratio of agreement between the thus compared data (agreement ratio), and determining that the plastics showing the highest agreement ratio is the type of the plastics of the unknown type. By using the above-mentioned agreement ratio, it is possible to simply and rapidly determine the type of a plastics by means of the differential spectrum of near-infrared rays.