JPS5910252B2 - Electrophotographic developer heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for heating an electrophotographic developer in the gas phase.

Generally, when heat-treating an electrophotographic developer, it is often necessary to heat the particles constituting the electrophotographic developer to a predetermined temperature while individually dispersing them.

In the production of electrophotographic developer powder, when an electrophotographic developer containing a thermoplastic resin, a colorant, etc. is produced by a crushing and granulation method, the shape of each particle is spherical. The electrophotographic developer may be heated to a temperature equal to or higher than the softening point of the thermoplastic resin in order to eliminate fine particles adhering to the surfaces of other particles by fusing and integrating them with the particles. This heat treatment is extremely effective, and in order to soften and fuse the entire surface of each particle, it is necessary to introduce the electrophotographic developer into a heated atmosphere in a state in which the individual particles are dispersed. In response to such demands, various heating devices have been proposed and used in the past, and they can be said to be sufficient for heating ordinary powder and granular materials.

However, in the conventional electrophotographic developer heating device,
The device itself does not have the function of dispersing the electrophotographic developer, or even if it does, the effect is very small25.
Therefore, if the powder to be heated exhibits cohesive properties, that is, if it is an intermediate powder of an electrically insulating one-component developer that exhibits cohesive properties due to electrostatic attraction, a plurality of particles may As a result, the yield of electrophotographic developer within the required particle size range becomes small. In order to avoid such a situation, it is possible to supply the electrophotographic developer to the heating device in much smaller amounts than in the past, but this would reduce the heating processing speed and cannot be used practically. However, an independent dispersion device is required to supply 35 in small quantities. Furthermore, when the electrophotographic developer is processed using a conventional heating device, the electrophotographic developer collides with or comes into contact with the material surrounding the inlet of the electrophotographic developer, and is fused to the surrounding material by heat and becomes agglomerated. This may cause a malfunction.

The electrically insulating one-component developer is a developer that is charged by friction and does not use a carrier. The present invention eliminates the above-mentioned drawbacks and provides an apparatus that can disperse a cohesive electrophotographic developer into individual particles and introduce them into a heating space, thereby reliably achieving the desired force skewering process. The purpose is to provide

An example of implementing the present invention will be described below with reference to the drawings, but the embodiments of the present invention are not limited thereby.

According to the present invention, as shown in FIG. 1, a housing 2 is provided which divides the heating chamber 1, and the lower part of the housing 2 is shaped like a circular fiber, and the cleft chamber 1 is evacuated from the tip of the housing 2. An exhaust blower 3 is provided in communication with the exhaust blower 3.

Further, an electrophotographic developer conduit 5 is provided which extends downward from the top of the case 2 and passes through the upper bottom wall 4 of the case 2 at the center thereof, and the lower end of this conduit 5 is opened. The conduit 5 is communicated with the heating chamber 1 to form an electrophotographic developer inlet 6, and the upper end of the conduit 5 is closed, but a cutout opening is formed in a part of the peripheral side wall near the upper end, and this is used to supply the electrophotographic developer. Let's say 7. Further, as shown in detail in FIG. 2, the electrophotographic developer inlet 6f1C forms a narrowed portion 8. That is, the lower end K$? of the conduit 5? A constriction member 9 is provided on the inner circumferential surface of the device, which has a small-diameter through hole in the center and expands into a conical shape at both ends of the through hole. Further, a cooling water flow passage 10 is formed on the outer periphery of the lower end of the conduit 5, and a partition plate 12 having an opening 11 surrounding the electrophotographic developer inlet 6 is connected to the body 2 through the cooling water flow passage 10. A conduit 13 is provided at a distance below the upper bottom wall 4 and communicates the space formed between the two with the atmosphere outside the body 2, and an electric heating element 14 is disposed inside the conduit 13. Reference numeral 15 denotes a feeder that supplies the electrophotographic developer to be heated to the electrophotographic developer inlet 7K.

Since the electrophotographic developer heating device of the present invention has a bank-like structure, it operates as follows to heat the electrophotographic developer in a state in which its constituent particles are individually dispersed.

That is, when the exhaust blower 3 is driven, the heating chamber 1 is exhausted, and the heating chamber 1 is filled with air from the outside atmosphere that has passed through the electrophotographic developer conduit 5 that enters from the electrophotographic developer supply port 7. is introduced from the electrophotographic developer inlet 6, and wind from the external atmosphere is introduced from the opening 11 through the passage pipe 13.
The resulting wind becomes hot air by energizing the electric heating element 14.

Therefore, the electrophotographic developer fed from the feeder 15 to the electrophotographic developer supply port 7 is guided by the wind down the conduit 5 and introduced into the heating chamber 1 via the electrophotographic developer inlet 6. However, since the electrophotographic developer inlet 6 is provided with a constriction section 8, the speed of the wind passing through the constriction section 8 increases rapidly, causing large turbulence.

Due to the force of this turbulent flow, the aggregated particles are dispersed into individual particles and enter the heating chamber 1, where the hot air from the opening 11 collides with the air from the electrophotographic developer inlet 6. Since the particles are stirred by the hot air, the particles are completely dispersed and heated by the hot air, and are guided downward with the air. Note that since the lower end of the conduit 5 is cooled by the cooling water flowing through the cooling water flow path 10, the electrophotographic developer inlet 6 and the narrowing member 9 do not reach high temperatures, and the electrophotographic developer is fused thereto. This will be prevented. Those skilled in the art can easily convert to using a cooling medium other than cooling water. Further, a cooling device such as cold air jetting or cold water spraying may be installed after the ducking chamber 1 to cool and solidify the heated and melted electrophotographic developer. As described above, the electrophotographic developer can be subjected to the desired heat treatment, but the axial length relative to the diameter in the narrowed portion 8
Specifically, the ratio of the length to the inner diameter of the through hole of the narrowing member 9 is preferably 5 or less.

This is because when the axial length is large, the wind passing through it becomes highly directional. This is because a unique air path is formed in the heating chamber 1, preventing mixing with hot air, resulting in incomplete heating of the electrophotographic developer. For the same reason, it is preferable that the amount of hot air from the opening 11 is at least half the amount of air from the electrophotographic developer inlet 6, and that the hot air is allowed to collide. In addition, when the narrowing section 8 imparts a dispersion effect to the electrophotographic developer, the velocity of the wind passing through the narrowing section 8 is adjusted when processing the aforementioned triboelectric developer intermediate powder. is preferably 10 m/Sec or more. Of course, this wind speed can be controlled by various means, such as the capacity of the exhaust blower, the diameter of the constricted portion 8, and so on. Note that a plurality of the narrowed portions 8 may be provided. As described in detail above, the electrophotographic developer heating device of the present invention has an extremely simple configuration, does not require a unique dispersion mechanism, does not require a reduction in processing speed, and is capable of handling cohesive powder particles. can be heated in a state where it is completely dispersed into individual constituent particles, and the desired heating effect can be used to produce spherical particles without forming agglomerates when used in the production of electrophotographic developers. There are significant benefits that can be achieved, such as the removal of welds.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of a heating device for an electrophotographic developer of the present invention, and FIG. 2 is an enlarged cross-sectional view of the main part of FIG. 1. 1...-JMoV chamber, 2...--Housing, 3...-Exhaust blower, 5...-Electrophotographic developer conduit,
6...Electrophotographic developer inlet, 8...Narrowed portion, 10...Cooling water flow path, 12...
- Partition plate, 15... feeder.

Claims (1)

[Scope of Claims] 1. Heat treatment of an electrophotographic developer, characterized in that a heat treatment apparatus for an electrophotographic developer having a hot air inlet and an inlet of an electrophotographic developer is provided with a cooling means around the outer periphery of the inlet of the electrophotographic developer. Device. 2. A heat treatment apparatus for an electrophotographic developer according to claim 1, wherein the electrophotographic developer is an intermediate powder of a one-component developer.