Abstract: A cylindrical composite paperboard cushion core for winding a sheet material therearound without forming undesirable stepwise marks thereon, comprises a cylindrical paperboard substrate and a cushion layer formed on the cylindrical paperboard substrate from an expanded paper sheet having a density of 0.1 to 0.4 g/cm.sup.3, the expanded paper sheet being formed by forming an unexpended paper sheet containing therein a plurality of expansible microcapsules each having a volatile liquid core contained in a thermoplastic resin shell and capable of starting an expansion at a temperature of 80.degree. C. to 200.degree. C., and heating the unexpanded paper sheet at the expansion-starting temperature of the microcapsules or higher, to cause the paper sheet to be expanded.

Abstract: A support sheet for a photographic printing sheet, having a high resistance to scratching, curling and a enhanced ability to be sharply cut, and provided with front and back surface coating layers formed respectively on the front and back surfaces of a substrate sheet and comprising, as a main component, a polyolefin resin; the polyolefin resin in the front surface coating layer comprising 30 to 70% by weight of a linear low density ethylene-propylene or butene-1 copolymer (L-LDPE) having a density of 0.915-0.935 g/cm.sup.3 and a melt index of 15-30 g/10 min and 30 to 70% by weight of a high pressure-processed low density polyethylene (HP-LDPE) having a density of 0.915-0.928 g/cm.sup.3 and a melt index of 1 to 5 g/10 min.

Abstract: A thermal transfer image-receiving sheet for a thermal transfer type printer comprises a sheet substrate, a front coating layer formed on the front surface of the sheet substrate and comprising a polyolefin resin, a polyolefin resin back coating layer formed on the back surface of the sheet substrate, and optionally, a surface coating layer formed on the front coating layer and comprising a resinous binder and a pigment.

Abstract: A support sheet for photographic printing paper having an undercoat layer on which a photographic emulsion layer is to be formed, and which is free from foaming, contamination by foreign substances, and putrefaction and does not effect the photographic emulsion, by the steps of coating front and back surfaces of a substrate sheet with polyolefin resins; surface-activating the front coating layer; and extrusion coating the activated surface of the front coating layer with a coating liquid comprising gelatin, through a slit-shaped orifice, to form the undercoat layer.

Abstract: A support sheet for photographic printing paper comprising a substrate sheet, polyolefin resin coating layers formed on the two surfaces of the substrate sheet, and an adhesive layer formed on a surface of the substrate sheet and one of the coating layers and comprising hydroxyethyl cellulose or a mixture of hydroxyethyl cellulose with one or more organic compounds having carboxyl radicals, the adhesive layer enabling the peel strength of the coating layer from the substrate sheet surface to be controlled to an appropriate peelable level of 10 to 200 g/25.4 mm determined in accordance with ASTM D903-49.

Abstract: A support sheet for photographic paper having an enhanced resistance to curling, especially twist-curling, comprises a substrate paper sheet composed of a half stratum portion thereof at the face side of a surface on which a photographic emulsion layer will be formed and the other half stratum portion thereof at the back side of the opposite surface, and two polyolefin resin coating layers on the two surfaces of the substrate paper sheet, the substrate paper sheet having a resiliency satisfying the relationships (I) and (II):1.5.ltoreq.E.sub.fl /E.sub.bt .ltoreq.2.25 (I)=and ##EQU1## wherein E.sub.fl =a modulus of elasticity of the face side half stratum portion in the longitudinal direction of the substrate, E.sub.bt =a modulus of elasticity of the back side half stratum portion in the transverse direction of the substrate, E.sub.ft =a modulus of elasticity of the face side half stratum portion in the transverse direction of the substrate, and E.sub.

Abstract: A support for photographic paper is produced by a method including the steps of coating one or two surfaces of a substrate sheet with a resinous melt includes a water-proof thermoplastic polymer and a pigment, by a melt-extrude-coating method, and solidifying the coating layer of the resinous melt on the substrate sheet, and wherein at least one melt-kneading procedure is applied to the resinous melt in a melt extruder having a pair of biaxial screws engaged with each other and satisfying the relationship (i)L.gtoreq.20D (I)wherein L is a length of the screws and D is a diameter of the screws, and provided with at least one pair of kneading disks located in at least a portion of the screws.