Importance

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Abstract

The invention provides a near-infrared absorbing material showing a high sensitivity to a YAG laser having an emission wavelength of 900.about.1100 nm as well as a high photothermal conversion efficiency, an original plate for direct printing plate making which utilizes the near-infrared absorbing material, and a novel polymethine compound represented by the following general formula (1), of which the above near-infrared absorbing material is comprised. 1 (wherein R.sub.1 and R.sub.3 each independently represents an unsubstituted or substituted alkyl group, a cycloalkyl group of 5.about.7 carbon atoms or an unsubstituted or substituted aryl group; R.sub.2 and R.sub.4 each independently represents an unsubstituted or substituted alkyl group or an unsubstituted or substituted aryl group; R.sub.5 and R.sub.6 each independently represents a hydrogen atom, an unsubstituted or substituted alkyl group or an unsubstituted or substituted alkoxy group; L represents an unsubstituted or substituted alkylene group of 2.about.4 carbon atoms which is necessary for formation of a cyclic structure; X represents a hydrogen atom, a halogen atom or a substituted amino group; Z represents a charge-neutralizing ion)

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First Claim