A method and device for separating a printing ink and a fiber by dry-process magnetic force difference coupled vibration. The device comprises a fiber crushing machine unit (1), a magnetic force difference coupled vibrator (2), an acceleration fan (3), a ballistic rebounding and resorbing device (4), a material settling and conveying pipe (5), and a cylindrical separator (6) which are sequentially connected by means of pipes. According to the method and the device, separation of printing inks and fibers in waste paper can be implemented by means of dry-process magnetic force difference coupled vibration, and recycling of waste paper products is implemented.

A processing device, a sheet manufacturing apparatus, a processing method, and a sheet manufacturing method that suppress damage to a substrate when removing color material from the substrate, and are useful for recycling the substrate after color material is removed, are provided. A processing device has a color material removal device including at least one discharge nozzle configured to discharge particles containing cellulose to a substrate holding color material, and remove the color material from the substrate. The color material removal device preferably has a double-walled conduit construction having an internal conduit and an external conduit in which the internal conduit is inserted, at least one of an opening to the internal conduit and an opening to the external conduit functioning as the discharge nozzle.

Provided is a processing device which includes a fluffing section for fluffing fibers contained in a sheet-like material, the fibers being at least near a surface of the sheet-like material, and a particle supplying section for supplying particles having Mohs hardness of 2 to 5 to the fluffed fibers. In addition, in such processing device, the particle supplying section preferably has an ejecting portion for ejecting the particles.

A processing device, a sheet manufacturing apparatus, a processing method, and a sheet manufacturing method enable quickly removing color material when color material is contained in a material containing fiber. A processing device has a defibrator configured to defibrate, in air, fibrous material containing fiber; and a particle supply device configured to supply particles of dry ice to the material containing fiber during defibration or after defibration. The material containing fiber contains color material; and the particles work to separate the color material for the fibers by colliding with the color material contained in the material containing fiber.

Provided is a method for producing paper and a pitch removal agent that can remove pitch efficiently. A pitch removal agent having an average polymerization degree of 300 to 2500, a saponification index of 70 to 88 mol % and satisfying, when the absorbance at a wavelength of 490 nm is designated as y (Abs) and the saponification index as x (mol %), the Numerical Formula (A) below is added to a pulp slurry during production of paper using waste paper in the step of deinking the waste paper by floatation and/or a step earlier:
y=0.0297x+b(A) (wherein, 70x88 and 2.80b3.03).

A processing device, a sheet manufacturing apparatus, a processing method, and a sheet manufacturing method enable quickly removing color material when color material is contained in a material containing fiber. A processing device has a defibrator configured to defibrate, in air, fibrous material containing fiber; and a particle supply device configured to supply particles of dry ice to the material containing fiber during defibration or after defibration. The material containing fiber contains color material; and the particles work to separate the color material for the fibers by colliding with the color material contained in the material containing fiber.

A processing device, a sheet manufacturing apparatus, a processing method, and a sheet manufacturing method that suppress damage to a substrate when removing color material from the substrate, and are useful for recycling the substrate after color material is removed, are provided. A processing device has a color material removal device including at least one discharge nozzle configured to discharge particles containing cellulose to a substrate holding color material, and remove the color material from the substrate. The color material removal device preferably has a double-walled conduit construction having an internal conduit and an external conduit in which the internal conduit is inserted, at least one of an opening to the internal conduit and an opening to the external conduit functioning as the discharge nozzle.

Provided is a processing device which includes a fluffing section for fluffing fibers contained in a sheet-like material, the fibers being at least near a surface of the sheet-like material, and a particle supplying section for supplying particles having Mohs hardness of 2 to 5 to the fluffed fibers. In addition, in such processing device, the particle supplying section preferably has an ejecting portion for ejecting the particles.

The control unit operates the stirring device sequentially in a defiberization operating mode, a transition operating mode, and a dilution operating mode. In the defiberization operating mode, the stirring blade is rotated at the revolution speed for defiberization of waste paper in the disaggregating water stored in the stirring chamber to generate a waste paper pulp slurry. In the transition operating mode, the dilution water from the water supply unit is supplied to the waste paper pulp slurry while rotating the stirring blade at the revolution speed for defiberization to stir the waste paper pulp slurry. In the dilution operating mode, the dilution water from the water supply unit is supplied to the waste paper pulp slurry while rotating the stirring blade at the revolution speed for stirring, lower than the revolution speed for defiberization, to stir the waste paper pulp slurry.

Provided is a method for producing paper and a pitch removal agent that can remove pitch efficiently.

A pitch removal agent having an average polymerization degree of 300 to 2500, a saponification index of 70 to 88 mol % and satisfying, when the absorbance at a wavelength of 490 nm is designated as y (Abs) and the saponification index as x (mol %), the Numerical Formula (A) below is added to a pulp slurry during production of paper using waste paper in the step of deinking the waste paper by floatation and/or a step earlier:

y=0.0297x+b(A) (wherein, 70x88 and 2.80b3.03).