JP2821799B2 - Method and apparatus for producing and recovering fine powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method and an apparatus for producing / recovering fine particles of organic photoconductor used for producing an electrophotographic photoreceptor. More particularly, the present invention relates to a method and an apparatus for generating and recovering fine powder by a gas evaporation method.

In the gas evaporation method, various substances are heated, evaporated and sublimated in an inert gas atmosphere introduced into a vacuum vessel, and the resulting vapor molecules are gradually cooled while colliding with the inert gas molecules, and the molecules are cooled. Are aggregated to form fine particle powder, and the fine particle powder is collected.

[Conventional technology]

An electrophotographic photosensitive member has a basic structure in which a photosensitive layer is formed on a conductive substrate. As a photoconductive material for forming the photosensitive layer, one using selenium has conventionally been generally used, and cadmium sulfide, zinc oxide and the like are also known as other inorganic photoconductive materials.

However, in recent years, attempts have been made to improve the film forming property by using an organic photoconductive substance, and to increase the productivity by producing by coating. When an organic photoconductive substance is used, there is an advantage that color sensitivity can be freely controlled by selecting a sensitizer such as a dye or a pigment to be used. Organic photoconductive materials include poly-N-vinylcarbazole and 2,5-bis (P-diethylaminophenyl)
1,3,4-oxadiazole and the like are known.

On the other hand, in recent years, various studies have been made on fine particle powder of the order of μm or Å. Such fine particle powder,
It is generated by paying attention to exhibiting high activity by increasing the specific surface area.

In this case, among others, the gas evaporation method is receiving attention.
Heretofore, this method had a direction of research on obtaining a fine particle powder of an inorganic or metallic material exclusively. For example, as described in "Functional Materials", June 1987, pages 44 to 49,
Research has also been conducted on obtaining organic fine particle powder.

In any case, conventionally, the recovery of the fine particle powder that has evaporated in the gas and adhered to the adherend has been performed as shown in FIG. 7 or FIG.

That is, the first method is, as shown in FIG. 7 (a), a container 50 for accommodating the evaporable material M, a flat or curved plate 51 as an adherend, and a container for collecting fallen powder as required.
52 is placed in a vacuum chamber (not shown), and while the inert gas is fed into the vacuum chamber and the inside thereof is evacuated to a vacuum state, the container 50 and / or the evaporative material M Is heated and evaporated, and the evaporated material is adhered to the curved plate 51, and thereafter, as shown in FIG.
The adhesion material layer on the surface is scraped off by the brush 53 or the like and collected in the collection box 54.

In the second method, as shown in FIG. 8 (a), a plastic web 60 as an adherend is wound on a reel 62 while being fed from the reel 61, and the surface of the web 60 is formed on the surface of the web 60 in the same manner as the first method. The evaporating material M is adhered in a suitable evaporating manner, and when the evaporating material M is collected, the web 60 is unwound from the reel 62 on which the web 60 has been wound up as shown in FIG. The conductive material M is scraped by a brush or the like and collected in the collection box 54.

Conventionally, there has been no restriction between the container 50 of the evaporable material M and the adherend, that is, the curved plate 51 or the web 60, by walls or the like.

[Problems to be solved by the invention]

However, when the material M evaporated from the evaporation source is freely adhered to the adherend as in the related art, the material M often scatters at places other than the adherend, and the temperature of the evaporation source may cause the material M to evaporate on the vacuum chamber wall or inside thereof. Since the disposed members are at a low temperature, the scattered materials are thermally deposited (adhered) to the inner wall of the vacuum chamber or to other internal members, and cannot be collected as a product.
It turned out that the recovery rate of the fine particle powder was poor. In addition, fine particle powder adhering to the vacuum chamber walls and internal members must be cleaned and removed before starting the next batch production, which requires a great deal of time and effort for cleaning. Had led to a decline.

Accordingly, an object of the present invention is to prevent the deterioration of the recoverability due to the scattering and thermal deposition of the fine particle powder, increase the recovery rate, and reduce the burden of cleaning the inner wall of the vacuum chamber.

[Means for solving the problem]

The above-mentioned subject is, in a method, a method in which fine particle powder evaporated from an evaporation source is attached to an adherend by an in-gas evaporation method, and the fine particle powder attached to the adherend is removed and collected. A scattering prevention wall is provided around the direction toward the adherend of the fine particle powder evaporated from the evaporation source toward the adherend,
In addition, the problem can be solved by connecting the passage for the inert gas to the inside of the scattering prevention wall.

In this case, the temperature of at least the inner surface of the scattering prevention wall is a temperature exceeding the thermal deposition temperature of the fine particle powder, and the temperature of the adherend is lower than the evaporation source temperature and the scattering prevention wall temperature, and It is preferable that the temperature be sufficient to cause thermal deposition. More preferably, the temperature is as low as possible, for example, it is desirable to cool to the temperature of liquid nitrogen.

Further, as an apparatus, an apparatus for attaching fine particle powder evaporated from an evaporation source by an in-gas evaporation method to a continuously moving adherend, and removing and collecting the fine powder attached to the adherend. In, a scattering prevention wall is provided around the direction from the evaporation source toward the adherend, the separation distance between the edge and the adherend,
This can be solved by being less than half the distance between the adherend and the evaporative material and, on the other hand, the passage of the inert gas communicating with the scattering prevention wall.

[Action]

According to the present invention, by providing a scattering prevention wall around the direction of the fine particle powder evaporated from the evaporation source toward the adherend, the scattering of the fine particle powder in the direction other than the adherend is prevented. This prevents heat deposition on the inner wall surface of the vacuum chamber and other members, so that the evaporated fine particle powder adheres only to the surface of the adherend, and the recovery rate of the fine particle powder (recovery) (The amount of the fine particle powder obtained / the amount of the charged raw material) is increased. For example, as shown in the examples described later, while the conventional recovery rate was about 20 to 50%,
According to the present invention, it is greatly increased to about 95%.

Further, in the present invention, since the passage of the inert gas is communicated with the inside of the scattering prevention wall, the fine particle powder rides on the flow of the introduced inert gas toward the adherend. Increases the adhesion rate.

Thus, the amount of the fine particle powder adhering to the inner wall of the vacuum chamber is extremely small, so that it is not necessary to perform cleaning for each batch, or even if cleaning is performed, cleaning can be performed very easily, thereby increasing productivity.

[Specific configuration of the invention]

 Hereinafter, the present invention will be described in more detail.

FIGS. 1 and 2 show a first embodiment of the present invention. In a vacuum chamber 1, a container 2 for an evaporable material M, an outer cylindrical rotating drum 3, and a part facing the same are open. A collection box 4 is provided. The vacuum chamber 1 has a supply pipe 5 for an inert gas G such as argon or helium,
The exhaust pipes 7 connected to the vacuum pump 6 are connected to each other, and the vacuum chamber 1 is provided with a pressure gauge 8 for detecting the degree of vacuum. The rotating drum 3 is located above the container 2. Further, the collection box 4 is formed of a heat shielding material, and is thermally shielded from a portion where the evaporable material M adheres to the storage container 2 and the rotating drum 3.

On the other hand, in the collection box 4, the outer cylindrical brush 9 having a large number of brush bristles 9 </ b> B around the brush roll 9 </ b> A is brought into contact with the surface of the rotation drum 3 via the opening of the collection box 4. It is provided with a rotation axis parallel to the rotation axis. Further, in the embodiment, the rotating drum 3 is rotated clockwise by a drive motor (not shown), and the brush 9 is configured such that a brush roll 9A is rotated clockwise by a drive motor (not shown). In this case, the rotating drum 3 and the brush 9 come in countercurrent contact. The rotation direction of the brush 9 can be reversed.

In the rotation range of the bristles 9B of the brush 9, the swing-off plate 10 is provided in a state fixed to the collection box 4.

Further, the container 2 of the evaporable material M is preferably formed of a heat-resistant material such as a ceramic, and the container 2 and / or the directly evaporable material M are heated by heating, induction heating, laser heating, resistance heating, or the like. The material M is heated to a temperature at which the material M is sufficiently evaporated by heating the electron gun or the like.
At that time, the rotating drum 3 is kept at a temperature in the vacuum chamber 1 and preferably cooled, for example, to 10 ° C. or less. This cooling can be performed by passing a cooling heat medium, such as cooling water, through the rotating drum 3. Also,
More preferably, cooling with liquid nitrogen.

On the other hand, in the present invention, a scattering prevention wall 11 is provided to prevent the scattering of the evaporated fine particle powder in a direction other than the direction toward the rotating drum 3 which extends from the storage container 2 to the adherend, that is, the rotating drum 3. ing. The upper end of the scattering prevention wall 11 shown in FIG. A heater 12 is attached to the scatter prevention wall 11, and the scatter prevention wall 11 is attached.
11 is to be heated.

Further, the blowing pipe 5 for the inert gas G communicates with the inside of the portion surrounded by the scattering prevention wall 11, and the inert gas G blown into the inside is filled with vapor molecules of the material M evaporated from below. The particles reach the vicinity of the rotating drum 3 while entraining the fine particles evaporating and rising by the suction force of the vacuum pump 6 by the suction force of the vacuum pump 6. After escaping into the vacuum chamber 1 through a gap between the rotating drum 3 and the vacuum chamber 1, the air is discharged to the outside.

In the apparatus configured as described above, the inside of the vacuum chamber 1 is depressurized by the vacuum pump 6 to a high vacuum, and then an inert gas is fed into the scattering prevention wall 11, preferably from 0.01 to
Keep at 50 Torr. When the evaporative material M is heated in this state, the gas evaporates, and the evaporated material M is continuously attached to the surface of the rotating drum 3 that is rotating. At this time, as in the embodiment, since the inert gas is blown into the scattering prevention wall 11, the inert gas evaporates and is cooled by the inert gas at a short time, and accompanied by the rise of the inert gas. Thus, the directivity to the surface of the rotating drum 3 increases.

Thus, the material M adhered to the surface of the rotating drum 3 is scraped off by the brush 9 contacting countercurrently at the contact portion and is collected in the collection box 4. Further, the material M adhered to the brush bristles 9B is scraped off similarly because the bristle tips come into contact with the scraping plate 10. The next new material is adhered to the surface of the rotating drum 3 that has been stripped and stripped of the material M. In this way, the attachment and scraping of the material M is continuously performed on the surface of the rotating drum 3.

Therefore, the material adhering to the surface of the rotating drum 3 is quickly scraped off again without receiving the radiant heat from the heat source for heating the material, so that there is no deterioration (thermal damage) due to heat as in the first conventional method. And high quality fine particle powder can be obtained. The time from evaporation attachment to scraping can be set, for example, by adjusting the rotation speed of the rotating drum 3.

When the amount of the fine particle powder recovered in the recovery box 4 reaches a certain amount, the operation of evaporating in gas is terminated, and the vacuum chamber 1 is opened to be taken out.

FIG. 3 shows a modification, in which a plurality of brushes 9X and 9Y are arranged on the rotating drum 3 in a plurality of illustrated examples. In this case, the scraping force of brush 9Y is
Can be greater than 9X scraping force.

The material, planting density, height, thickness, and the like of the brush bristles 9B can be appropriately selected. As a material, usually metal fibers are used,
Carbon fibers and the like can also be used. Rotating drum 3
As for the material of, appropriate materials can be used,
Usually, a metal thing can be used.

On the other hand, as a means for removing and collecting the fine particle powder adhering to the rotating drum 3 from the surface of the rotating drum 3, for example, a scraping blade 91 shown in FIG. A method or a method using the wiping web 92 shown in FIG. 5 can be adopted. In the case of the wiping-off web 92, the fine particle powder adhering to the web 92 is recovered from the web 92 after winding.

Further, as the adherend, as in the above-described example, the fine powder is attached while continuously rotating the adherend, and the fine powder is continuously removed while rotating the adherend continuously. Although it is preferable in order to reduce the thermal deterioration of the substrate, the conventional adherend shown in FIGS. 7 and 8 can be used as it is.

In the present invention, the upper end of the scattering prevention wall 11 is an adherend,
In the embodiment, it is not always necessary to be close to the rotating drum 3. That is, as shown in FIG. 2, when the distance l between the upper end of the scattering prevention wall 11 and the rotary drum 3 is more than 1/2 of the distance L between the rotary drum 3 and the material M. This is because the evaporated fine particle powder exhibits directivity due to the presence of the scattering prevention wall 11, and the rate of scattering becomes extremely small. However, it is generally desirable that the distance l be equal to or less than 20 mm.

By the way, the temperature of at least the inner surface of the scattering prevention wall 11 is
For example, it is preferable to set the temperature to be higher than the thermal deposition temperature of the fine particle powder by the heater 12 in order to prevent thermal deposition. Thermal deposition (TheramalPrecipitation) is a phenomenon in which evaporated fine particles adhere (deposit) to a wall due to a temperature gradient near the wall due to a thermophoretic phenomenon.

In addition, the temperature of the adherend is less than the temperature of the evaporation source temperature (the temperature of the evaporative material) and the temperature of the scattering prevention wall 11, and is not more than the temperature at which the fine particle powder is sufficiently thermally deposited.
It is desired that the temperature be as low as possible and that a large thermal gradient be established between the evaporation source temperature and the adherend.

Since the setting of such a temperature basically depends on the type of the target material, it is appropriately set accordingly.

In each of the above examples, the evaporable material is supplied to the storage container in a batch manner, but a large amount of evaporation can be performed by continuously supplying the evaporable material to the heating container in the vacuum chamber by a screw feeder or the like.

In the present invention, the target fine particle powder can be suitably applied when obtaining ultrafine particles of 100 to several tens of thousands, particularly ten to several thousand of particles. The type of the fine particle powder may be an inorganic material, a metal material, or an organic material. In particular, the present inventors, an organic pigment when obtaining an organic photoreceptor,
In particular, it has been confirmed that it is optimal for obtaining an anthranthrone pigment.

The organic photoreceptor can be generally obtained by applying organic photoconductor particles dispersed in a binder resin by a disperser or other layers on a conductive substrate.

In this case, the photoconductor finally obtained includes a single-layer photoconductor in which organic photoconductor particles (pigment) are dispersed in a charge transport material as a charge generation material on a conductive substrate; There is a function-separated type photoreceptor in which a charge generating material layer is formed on a conductive substrate and a charge transporting material layer is formed thereon.
The present invention is suitable for obtaining fine particle powder in the production of both types of photoconductors.

〔Example〕

 Next, examples will be shown to clarify the effects of the present invention.

(Example 1) Evaporation in gas was performed by the apparatus shown in FIG.

Organic pigment fine-particle powder used for manufacturing an organic photoreceptor for electrophotography was generated and collected. As this organic pigment, 4,10-dibromoanthran is used, the vacuum chamber is placed under a helium gas atmosphere, the pressure is reduced to 10 ^-1 Torr, the material is heated to 300 to 350 ° C., and the material is evaporated in vacuum to obtain To obtain a fine particle powder. The distance L between the material M and the surface of the rotating drum 3 was 95 mm, and the distance l between the scattering prevention wall 11 and the rotating drum 3 was 10 mm.

As a result, fine powder without thermal degradation was recovered with a recovery rate of about 95%.

On the other hand, for each batch, without cleaning the inside of the vacuum chamber, only cleaning of the residue of the evaporation source and preparation of new raw materials were performed, and a continuous operation of 5 times or more was repeated.
No difference was found in the quality of the collected fine particle powder for each operation.

(Comparative Example 1) The recovery rate of the fine particle powder was examined in the same manner as in the example except that the scattering prevention wall was not provided, and it was about 45%. Furthermore, after one operation, the inside of the vacuum chamber was inspected, and a large amount of fine particle powder was found to adhere to the inner wall, and it was necessary to remove and clean it before moving on to the next operation. Was clearly recognized.

(Comparative Example 2) On the other hand, when the separation distance L between the material M and the surface of the rotary drum 3 was variously changed under the same conditions as in Comparative Example 1, the recovery rate greatly depends on the separation distance L as shown in FIG. It turned out to be.

Conversely, if the separation distance L is extremely short, the recovery rate is increased. For example, when the distance is 30 mm, the recovered powder is in a thread form, and the inside thereof is orange and the surface is crimson. The effect of thermal degradation was clearly observed.

〔The invention's effect〕

As described above, according to the present invention, the recovery rate is increased, the burden of cleaning the inner wall of the vacuum chamber is reduced, and the productivity is increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a first embodiment of the present invention, FIG. 2 is an enlarged view of a main part of the modification, FIGS. 3 to 5 are schematic diagrams of the modification,
FIG. 6 is a graph showing a change in the recovery rate, and FIGS. 7 and 8 are schematic explanatory diagrams of the prior art. DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2 ... Container, 3 ... Rotary drum, 4 ... Collection box, 6 ... Vacuum pump, 9 ... Brush, 11 ... Scatter prevention wall, 12 ... Heater, M ... ... Evaporative material, G ... Inert gas

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B01J 19/00 B22F 9/12 G03G 5/00

Claims (4)

(57) [Claims] 1. A method for adhering fine particle powder evaporated from an evaporation source to an adherend by an in-gas evaporation method, and removing and recovering the fine particle powder adhering to the adherend, comprising: A fine particle powder, wherein a scattering prevention wall is provided around a direction of the fine particle powder evaporated toward the adherend toward the adherend, and a conduit for an inert gas is communicated with the scattering prevention wall. How to create and recover your body. 2. The method according to claim 1, wherein the temperature of at least the inner surface of the scattering prevention wall is higher than the thermal deposition temperature of the fine particle powder. 3. The method according to claim 1, wherein the temperature of the adherend is lower than the temperature of the evaporation source and the temperature of the scattering prevention wall, and is a temperature at which sufficient thermal deposition of the fine particle powder occurs. 4. An apparatus for adhering fine particle powder evaporated from an evaporation source by an in-gas evaporation method to a continuously moving adherend, removing and recovering the fine particle powder adhered to the adherend, A scattering prevention wall is provided around the direction from the evaporation source toward the adherend, the separation distance between the edge and the adherend is not more than 1/2 of the distance between the adherend and the evaporable material. On the other hand, an apparatus for generating and recovering fine particle powder, wherein a passage for an inert gas is communicated with the inside of the scattering prevention wall.