Abstract: Provide a bulky paper that provides improved paper-strength properties such as higher tensile strength without increasing paper density, while also offering good optical characteristics such as opacity and brightness, wherein the paper is produced by: (a) blending polyacrylamides that have an electric charge of 2.0 m-equivalent/g or less at pH2 and also 2.0 m-equivalent/g or less at pH12; (b) adding fillers comprising amorphous silica or silicate with a specific bulk density of 0.3 g/ml or less, bulk-increasing agents comprising fatty-acid polyamide compound or of ester compound of polyhydric alcohol and fatty acid, and/or mercerized pulps or bridged pulps; and (c) adjusting the relative bonding area of the paper containing polyacrylamides to 1.2 times the relative bonding area of a paper not containing polyacrylamides, or less.

Abstract: Produce a printing paper that offers sufficient bulk and flexibility by using a bulk-increasing/softening agent with a HLB of 6 or below, which is either a liquid or a solid with a melting point of 40° C. or below, wherein the agent may be an ester compound of polyhydric alcohol and higher fatty acid or a long-chain alkyl ammonium salt, and by adjusting the surface temperature of the paper during a preheating drying period (a period during a drying process before the temperature of a wet paper becomes constant) to at least 10° C. higher than the melting point of the bulk-increasing/softening agent.

Abstract: A thermally sensitive recording medium that contains a compound represented by general formula (1) as a color developer, and a compound represented by general formula (2) or general formula (3) as a sensitizer. The said thermally sensitive recording medium has sufficient color developing sensitivity with lower impressive energy, and has good image preservability of recorded part, good resistance to humid and heat resistance of background white paper part. In the formulae, R1 represents a hydrogen atom, a methyl group or a chlorine atom, R2 and R3 represents a methyl group, an alkoxy group or an allyloxy group, m and n represents an integer of 1-5, R4 represents an alkyl group, an alkoxy group of carbon number 1-6 or an electron withdrawing group and o represents an integer of 0-2.

Abstract: The present invention is a thermally sensitive recording medium which has excellent anti ultra violet ray property, mainly composed of an electron donating compound and an electron accepting compound, containing at least one of benzoxadinone compound represented by general formula (1) as an ultra violet ray absorbing agent. In the above mentioned formula, R represents hydrogen atom, hydroxyl group, alkyl group of carbon number 1-8, alkoxy group of carbon number 1-6, acyl group of carbon number 1-6, acyloxy group of carbon number 1-6, alkoxy carbonyl group of carbon number 1-6, carboxyl group, halogen atom or nitro group and X represents a divalent group or a direct bond.

Abstract: A thermal sensitive recording medium which further contains poly urea compound in the thermal color developing layer containing dye precursor and color developer, which displays an excellent image preservative stability. Said poly urea compound contains units of a structure represented by general formula (1), and further contains a repeating unit represented by general formulae (2).about.(7). ##STR1## In these formulae A.sup.1 .about.A.sup.7 are a divalent group, R.sup.1 .about.R.sup.5 are an alkyl group, an alkoxy group or an electron accepting group, o, p, and q are an integer from 0 to 4, r is an integer from 2 to 12 and s and t are an integer from 0 to 8.

Abstract: A phenanthridine derivative metal complex of formula 1 having a large absorption in the near-infrared range and a reduced absorption in the visible range, which phenanthridine derivative metal complex is used in a transparent recording medium: ##STR1## where M is a metal atom, and X is a negative ion.

Abstract: An acridine derivative metal complex of formula 2 having a large absorption in the near-infrared range and a reduced absorption in the visible range, which acridine derivative metal complex is used in a transparent recording medium: ##STR1## where M is a metal atom, and X is a negative ion.

Abstract: An acridine derivative metal complex of formula 1 or formula 2 having a large absorption in the near-infrared range and a reduced absorption in the visible range, which acridine derivative metal complex is used in a transparent recording medium: ##STR1## where M is a metal atom, and X is a negative ion.

Abstract: A heat-sensitive recording sheet has on a support a color-developing layer which comprises a colorless or pale colored basic chromogenic dye and an organic color-developing agent, wherein the organic color-developing agent comprises both 4-hydroxy-4'-n-propoxydiphenylsulfone and a particular phenolic substance. The sheet of this invention provides excellent writing quality and superior thermal responsibility.

Abstract: A heat-sensitive recording sheet of this invention comprises in a heat-sensitive color-developing layer both 4-hydroxy-4'-n-propoxydiphenylsulfone as an organic color-developing agent and a particular fluorane-leuco dye. This sheet provides an intense, clear image, less discoloration, and stable brightness.