Abstract: A photographic film spool is comprised of a spool core which includes a pair of flanges, a slot for film insertion, and a pair of walls. The walls face each other and form the slot for film insertion. One of the walls of the spool is provided with a ramp portion which is formed so as to approach the other wall gradually in the direction of film insertion, a retention hook which is provided at the top of the ramp portion and which engages an aperture of the trailing end of the photographic film, and penetrated portions which are formed on both sides of the retention hook and which penetrate the one wall in the direction perpendicular to the direction of film insertion. The other wall has a hold-down projection which inhibits the photographic film from becoming detached from the retention hook. The spool allows easy removal of the trailing end of the photographic film from the spool core without damage after use.

Abstract: An injection mold for injection-molding a tubular article having a bottom at one end and opening at the other end having a cavity plate and a core which define a cavity conforming to the shape of the article when closed. A gate opens to the cavity at a portion defining the bottom of the article. The core is provided with a coolant passage for circulating coolant up to a portion near the free end surface of the core for defining the bottom of the article. The inner surface of the core defining the end portion of the coolant passage near the free end surface of the core tapering toward the gate and the coolant passage extends near a portion of the free end surface of the core opposed to the gate, and at least one rib is provided on the inner surface of the core at the tapering portion to project into the coolant passage and to extend in parallel to the direction of coolant flow.

Abstract: S/N characteristic and durability of recording medium e.g. video tape or magnetic disket are improved by using as bonding resin used in the magnetic paint to make the magnetic layer a polyester-based polyurethane having a number average molecular weight of 5,000-100,000 and containing at least two hydroxyl group and at least one sulfone bond therein, through improvement of dispersibility of fine magnetic powder in the magnetic paint.

Abstract: An injection mold for molding a tubular article having a closed end comprises a stationary mold half including a cavity plate having at least one cavity impression and a movable mold half which is movable between a closed position and an open position and is provided with at least one core portion for defining a cavity together with the cavity impression when the movable mold half is moved to the closed position. A recess is formed in the top face of the core portion and a telescopic mold piece is fitted into the recess in such a manner that a narrow space is formed therebetween. An air chamber having a relatively large volume is formed in the vicinity of the top face of the core portion. The air chamber is communicated with the space over the top face of the core portion by way of the narrow space between the mold piece and the recess, and with the atmosphere by way of a communicating passage formed in the core portion.