Magnetic tape cartridge having characterized winding deviation occurance load and magnetic tape device

A magnetic tape cartridge comprising:

• a magnetic tape;
• and
• a cartridge reel,
• wherein, in the magnetic tape, a minimum winding deviation occurrence load measured after the magnetic tape is rewound around the cartridge reel by applying a tension of 0.30 N in a longitudinal direction of the magnetic tape is 250 N or less,
• the minimum winding deviation occurrence load being obtained by the following method at 23° C. and 50% relative humidity:
• providing an unused magnetic tape cartridge;
• temporarily extracting the entire length of the magnetic tape from the cartridge by applying a tension of 0.30 N in the longitudinal direction of the magnetic tape and winding the magnetic tape around a temporary winding reel;
• rewinding the entire length of the magnetic tape from the temporary winding reel around the cartridge reel by applying a tension of 0.30 N in the longitudinal direction of the magnetic tape;
• extracting the cartridge reel around which the entire length of the magnetic tape is wound from the cartridge, said cartridge reel including at least a reel hub and optionally flanges protruding outward in a radial direction from an upper end portion and a lower end portion of the reel hub, respectively;
• for a cartridge reel having flanges, removing the flanges to expose both sides of a tape winding surface around which the magnetic tape is wound;
• installing the reel hub on a cradle;
• placing an aluminum ring having an outer diameter of 90 mm and an inner diameter of 80 mm on the tape winding surface of the wound magnetic tape installed on the cradle so that the center of rotation of the reel hub and the center of the aluminum ring match to each other within a deviation of 3 mm or less;
• placing an aluminum plate having a square shape of 100 mm×100 mm and a thickness of 3 mm in a plan view on the aluminum ring;
• and
• applying a load from the top of the plate, holding it for 10 minutes, and then removing it, in the following manner:
• in a case where the position in a vertical direction of the upper surface of the plate before applying the load is defined as A, the position in the vertical direction of the upper surface of the plate after removing the load is defined as B, and “A−B≥1 mm” is satisfied, it is considered that an unwinding has occurred on the wound magnetic tape;
• starting the load application from 5 N with respect to the magnetic tape being measured, performing measurements while increasing the load in increments of 5 N, and defining the minimum load at which said unwinding is considered to have occurred as the minimum winding deviation occurrence load.