Abstract: A recording medium comprising a substrate and a recording layer arranged on the substrate, said recording layer being removable by irradiation of radiation having high energy density thereto through evaporation or fusion in the area having received said irradiation, which is characterized in that said recording layer comprises indium and at least one metal compound selected from the group consisting of a metal sulfide, a metal fluoride and a metal oxide and contains at least one metal showing a surface tension of not less than 600 dyne/cm within temperatures of the melting point thereof to a temperature higher than the melting point by 300.degree. C.

Abstract: An information recording medium including a substrate, an optional intermediate layer arranged on the substrate, and a recording layer arranged on the intermediate layer on the substrate, the recording layer including a low melting metal selected from the group consisting of In, Te, Sn, Pb and Bi and a metal compound selected from a metal sulfide, a metal fluoride and a metal oxide. The recording layer further contains a metal having a high surface tension of not less than 600 dyne/cm within temperatures from its melting point to a temperature higher than the melting point by 300.degree. C., the concentrations of the metal varying along the depth direction of the recording layer in such manner that the concentration of the metal on the side facing the substrate is higher than that of the metal on the opposite side where the metal on the side facing the substrate may be in the form of islands.

Abstract: A laser recording material is described, comprising a transparent glass base and a recording layer capable of writing and/or reading information by means of a laser, wherein said glass base has an undercoating layer between the glass base and the recording layer, comprising a carboxyl group-containing polymer or a maleic anhydride copolymer.

Abstract: An information recording medium comprising in order, a glass substrate; a layer for preventing diffusion of alkali metal ions and alkaline earth metal ions from the substrate; a thermal barrier layer, and an information recording layer for writing and/or reading information by means of laser beam.

Abstract: A method of recovering waste paper of a pressure sensitive copying paper which comprises, in the defibration processing for regenerating the waste paper, using an alkaline solution containing a surface active agent. This method provides a white pulp which is hardly stained.