JPH01184031A - Batch type wet disperser and method for dispersing electrophotographic receptor coating liquid utilized therewith - Google Patents

Abstract

PURPOSE:To form a photosensitive layer free from generation of a picture image defect by utilizing a batch type wet disperser in which a rotary dispersion means allows to be rotated in a vessel provided with a middle cover between the rotary dispersion means and a top cover of the uppermost part of the disperser. CONSTITUTION:A batch type wet disperser is constituted by arranging a shaft 5 provided with disks 3 in a vessel 1 surrounded with a jacket 2. Rotating drive is conducted to the disks 3 from a driver 4 via the shaft 5 and liquid to be dispersed is agitated by the rotational motion of the disks 3 and dispersed. In this disperser, a middle cover 7 is provided between the uppermost part of the disk 3 and the top cover 6 of the uppermost part of the vessel 1, namely to the slightly upper part of a mixture of the liquid to be dispersed and a medium shown in a shaded part. When utilizing this disperser, the liquid can be efficiently dispersed in a short time and dispersed in uniform and stable fine particles.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a batch type wet dispersion device and a dispersion method using the device. The present invention relates to a vertical batch type wet dispersion device for wet dispersing a liquid to be dispersed by dispersing a liquid to be dispersed, and a dispersion method using the device.

[Conventional technology]

Up to now, various types of dispersion devices for dispersing solids such as pigments and dyes have been considered, such as roll mills, ball mills, vibrating ball mills, attritors, and colloid mills.

However, in recent years, demands for miniaturization have become even higher, and improvements have been made to dispersion devices in response to this demand.

An effective means for finely dispersing pigments, dyes, etc. is to use a so-called sand mill dispersion device in which a medium such as glass beads is placed inside a vessel and a disk or drum serving as a rotational dispersion means is rotated to finely disperse the medium. When dispersing pigments and the like using a sand mill, there are continuous dispersion methods that have a mechanism for circulating the liquid to be dispersed, and batch-type dispersion methods that do not have this mechanism. In the case of a continuous dispersion method, the dispersion liquid is filled in the vessel, which has the advantage of improving dispersion efficiency, but in order to perform circulation, a liquid reservoir is required for the pump, piping, or equipment. , a large amount of the liquid to be dispersed is required, and the actual dispersion time is
That is, there is a drawback that the residence time in the vessel is short. In addition, in the case of a liquid to be dispersed whose viscosity increases, a bypass phenomenon occurs within the vessel (when the liquid to be dispersed is circulated from the bottom to the top of the vessel, pressure is concentrated in the lower viscosity part of the liquid to be dispersed). , a phenomenon in which the liquid to be dispersed flows upward due to insufficient dispersion) is likely to occur, and there is a high possibility that some areas will be dispersed and others will not be dispersed, making uniform dispersion difficult.

On the other hand, in the batch type dispersion method, the bypass phenomenon does not occur, and the residence time in the vessel is not shortened.

However, in batch-type systems, there is a dead space between the top lid and the dispersion liquid, and the dispersion liquid and medium are often splashed away by the uppermost disk or drum.
The disadvantage was that the dispersion efficiency was significantly lower than that of the continuous method.

As described above, with conventional methods, it has been extremely difficult to disperse fine particles with good dispersion efficiency in a short time.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a dispersion device that eliminates the above-mentioned drawbacks, and provides a dispersion device that can uniformly and stably disperse fine particles with good dispersion efficiency in a short time. That's true.

Another object of the present invention is to provide a dispersion device that can form a liquid to be dispersed with small particle sizes without causing coating defects.

Another object of the present invention is to provide a method for dispersing an electrophotographic photoreceptor coating liquid that can form a photosensitive layer that does not cause image defects.

[Means for solving problems]

That is, the present invention provides a batch-type wet dispersion apparatus that performs dispersion by rotating a rotary dispersion means within a vessel, which has an inner lid between the top of the rotary dispersion means and an upper lid at the top of the dispersion device. This is a batch type wet dispersion device characterized by the following.

The present invention also provides a method for dispersing an electrophotographic photoreceptor coating liquid containing a pigment or dye using a batch-type wet dispersion device in which a rotary dispersion means is disposed in a vessel. A method for dispersing an electrophotographic photoreceptor coating liquid, which comprises dispersing an electrophotographic photoreceptor coating liquid in a vessel by providing an inner lid between an upper lid and rotating the rotational dispersion means. It is.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of the dispersion device of the present invention. The basic configuration of the device is composed of a vessel 1 and a disk 3. Specifically, a shaft 5 having a disk 3 is disposed in a vessel l surrounded by a jacket 2, and the rotational drive from the drive device 4 is transmitted to the disk 3 via the shaft 5. The rotational movement stirs and disperses the liquid to be dispersed. In the present invention, an inner lid 7 is provided between the top of the disk 3 and the upper lid 6 at the top of the vessel, that is, slightly above the mixture of the liquid to be dispersed and the medium shown by the hatched area in FIG. In this specific example, as shown in FIG. 2, the inner lid 7 is provided with a positioning adjustment screw 8, and the height of the inner lid 7 is adjusted by the positioning adjustment screw 8, so that It is designed so that it can be fixed with a pig 6 and a nut 9.

The optimal height of the medium pot and the liquid to be dispersed varies depending on the viscosity of the liquid used for dispersion and the type of medium used, but it is preferable to set the medium pot at a height of 5 to 20 cm above the liquid surface. .

The inner lid is located inside the vessel regardless of the movement of the shaft 5, and no relative velocity occurs between the outer circumference of the inner lid and the inner wall of the vessel in contact with it. If a relative speed occurs, that is, if the inner lid rotates in the middle of the vessel, the liquid to be dispersed may leak from the outer periphery of the inner lid, which is not preferable.

The inner lid may have any shape as long as the liquid to be dispersed does not leak into the upper part of the inner lid, and a circular or conical inner lid is also possible. Alternatively, as shown in FIG. 1, a type having a Teflon backing on the outer periphery of the inner lid so as to be in close contact with the inner wall of the vessel may be used. In particular, a downward conical inner lid has the advantage that if the liquid to be dispersed leaks into the upper part of the inner lid, the liquid leaking from the center can easily return.

The method of fixing the inner pig shown in the specific example of the present invention is one example, and the fixing method is not limited to this.

For example, as another method, the inner lid may not be provided with a positioning adjustment screw, but a fixing metal fitting may be provided inside the vessel, thereby fixing the inner lid.

The fixing metal fittings may be fixed within the vessel or may be removable.

The upper lid attached to the top of the vessel may be of any shape, and may be rod-shaped, for example, as shown in FIG. 3, for fixing the inner lid.

As the rotational dispersion means, it is possible to use not only a disk as shown in FIG. 1 but also a drum, and pins may be provided inside the drum, disk, or vessel.

By dispersing pigments, dyes, etc. using such a dispersing device, it is possible to form a uniform dispersion of pigments, dyes, etc. in a short time. In particular, it is an effective means for dispersing charge/generating substances such as pigments and dyes contained in electrophotographic photoreceptor coating liquids that require a fine dispersed particle size.

Pigments and dyes that can be dispersed in the present invention may be either inorganic or organic, such as azo pigments, phthalocyanine pigments,
Anthrone pigment, dibenzpyrenequinone pigment, pyranthrone pigment, indigo pigment, quinacridone pigment,
Examples include asymmetric quinocyanine, quinocyanine-bilylium dyes, and metal oxides. An example is shown below.

The present invention is extremely effective even when dispersing substances other than the following substances, and the substances to be dispersed used in the present invention are not limited by the following substances.

(1) Zinc oxide (2) Titanium oxide (3) Tin oxide (4) Cadmium sulfide (lO) (25)　　　　　　　　　.

(27) Squaric acid methine dye (28) Indigo dye (C,1
, No. 78,000) (29) β-type copper phthalocyanine (40) Type metal-free phthalocyanine These pigments and dyes are dissolved in a suitable organic solvent, such as tetrahydrofuran, cyclohexanone, methyl ethyl ketone, ethyl acetate, methanol, methylcellosolve.

A liquid to be dispersed is prepared using acetone, dioxane, N,N-dimethylformamide, or the like as a dispersion medium. At this time, a polymeric substance may be added together as a binder, or the binder may be added after the pigment etc. and a dispersion medium are predispersed.

The binder can be selected from a wide variety of insulating resins and also organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane resin , epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, and other insulating resins.

The ratio of the solid content including the pigment or dye and the binder to the dispersion medium may be about 0.5 to 80% by weight. Especially when dispersing the charge generating substance of the electrophotographic photoreceptor, 3.
~15% is preferred. The amount of the binder can be appropriately selected depending on the pigment to be dispersed.

Example 1-10 Ten types of pigments were dispersed using a dispersion device using a medium pig as shown in FIG. Table 1 shows the respective dispersion conditions. Note that the binder was added from the start of dispersion.

The number of disks was four, and four pins with a height of 10 mm and a diameter of 8 mm were attached to the underside of the disks. During dispersion, glass beads (GB-201M, manufactured by Toshiba Varotech 2) were used as a medium, and the volume ratio of the beads to the liquid to be dispersed was 1:l.

The particle sizes after dispersion in Examples 1 to 10 and the particle sizes after being rotated at 1 rpm on a rotating stand for 5 days are shown below.

The rotary pedestal here is similar to a ball mill, and is a device that rotates a bottle placed on the pedestal at a constant angular velocity.

The particle size was measured using a centrifugal particle size distribution analyzer (CAPA500) manufactured by Horiba, Ltd. based on the liquid phase sedimentation method, and the average particle size was used.

As a comparative example, dispersion was carried out under the same conditions as in Table 1 using a dispersing device without an inner pig. The particle sizes after dispersion of Comparative Examples 1 to 10 and the particle sizes after being left to rotate on a pedestal in the same manner as in Examples are shown below.

As is clear from the above results, when a dispersion device using a medium pig is used, the pigment in the liquid to be dispersed is finely dispersed, and the particles hardly increase even when rotated on a stand.

On the other hand, in Comparative Examples 1 to 10 in which no inner pig was used, the particle size after dispersion was larger than that in which a middle pig was used, and the dispersion was insufficient for the same dispersion time as in the examples.

Furthermore, if left under rotation for 5 days, all of the particles increase in size, resulting in considerably large particle sizes, and some gel-like particles appear.

Furthermore, among the liquids to be dispersed which were left to rotate for 5 days, the liquid of Example 2 was mixed with cyclohexanone/methyl ethyl ketone = 1/l.
The solution was diluted to 2% by weight using a mixed solvent (weight ratio), and applied to a 50 μm aluminum sheet using a wire bar. In addition, in the same manner, Examples 3, 4, 6.7, and 8 were prepared with tetrahydrofuran solvent, Example 9 was prepared with butyl acetate, and Example 10 was prepared with methyl ethyl ketone, each at a concentration of 2% by weight. and coated on a 50 μm aluminum sheet. When I observed these coatings, I noticed that
A clean coating film with no spots was obtained.

In addition, when Comparative Examples 3, 4, 6, 7, 8.9 and IO were diluted to a 2% by weight solution and applied to an aluminum sheet in the same manner as above, Comparative Examples 3, 6, 7, 8. 9 and 1
In case of No. 0, spots made of aggregates were observed on the coating film.

As described above, by dispersing using a dispersing device using a medium pig, a stable liquid to be dispersed with a small particle size can be obtained in a short time.

Comparative Example 11 Dispersion was carried out in the same manner as in Example 2, except that a dispersing device without an inner pig was used. However, the dispersion time was 44 hours.

Comparative Example 12 Dispersion was carried out in the same manner as in Example 8, except that a dispersion device without an inner pig was used. However, the dispersion time was 100 hours.

The particle sizes after dispersion of Comparative Examples 11 and 12 are shown below.

The proportions of particles with a diameter of 0.10 μm or less in Example 2 and Comparative Example 11 were 70% and 60%, respectively (in terms of volume). Further, the proportions of particle sizes of 0.20 μm or less in Example 8 and Comparative Example 12 were 85% and 65%, respectively.

Therefore, when dispersing is performed using a medium pig, the particle size distribution is narrower even if the average particle size is about the same, and a uniform liquid to be dispersed can be obtained.

Example 11 80φ x 300m with 3μm thick casein undercoat treatment
The dispersion prepared in Example 2 as a coating solution for an electrophotographic photoreceptor was coated on an aluminum cylinder of 1 by dipping method.
It was dried at 00° C. for 10 minutes to form a charge generation layer with a thickness of 0.9 μm.

Next, the hydrazone compound lO part of the following structural formula, styrene-
10 parts of acrylic resin (MS-200, manufactured by Nippon Steel Chemical Co., Ltd.) was dissolved in 80 parts of monochlorobenzene, and this solution was applied onto the charge generation layer by a dipping method, and dried with hot air at 100°C to form a charge transport layer with a thickness of 12 μm. was formed to produce an electrophotographic photoreceptor.

Comparative Example 13 An electrophotographic photoreceptor was produced in the same manner as in Example 11 except that the dispersion formed in Comparative Example 2 was used as a coating liquid for an electrophotographic photoreceptor. However, in this case, coating unevenness was visually observed during the formation of the charge generation layer. In addition, blurring due to particle aggregation was observed at the edges of the coating film.

The electrophotographic photoreceptor thus manufactured was heated to -5°6K.
Copies were made by attaching the copying machine to an electrophotographic copying machine which has V-corona charging, image exposure, toner development, toner transfer to plain paper, and cleaning steps using a urethane rubber blade.

In the electrophotographic photoreceptor of Example 11 using a dispersing device equipped with an inner pig, good images without image defects were obtained.

On the other hand, the electrophotographic photoreceptor of Comparative Example 13 using a dispersing device without an inner lid had image defects such as white spots and fog.

As described above, by dispersing according to the present invention, fine particles can be dispersed in a short period of time, and the coated film surface is even, so a good image without image defects can be obtained.

〔Effect of the invention〕

As explained above, ζ
By carrying out the dispersion, it is possible to perform fine dispersion efficiently in a short time, and moreover, it is possible to disperse the particles into uniform and stable fine particles. Further, according to the method of dispersing a coating liquid for an electrophotographic photoreceptor of the present invention, a photosensitive layer without image defects can be formed.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a specific example of the dispersion device of the present invention, Fig. 2 is a plan view and a cross-sectional view of a middle lid in an integrated example of the dispersion device of the present invention, and Fig. 3 is a plan view of an upper lid of the dispersion device. Show the diagram. l ・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・Vessel 2・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・Jacket 3 ・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Disc 4
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・Drive device 5・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Shaft 6・・・・・・・・・・・・
・Vessel top top cover 7・・・・・・・・・Vessel inner cover 8・・・・・・・・・Position adjustment screw 9・・・・・・・・・・・・...Natsuto

Claims (4)

[Claims] (1) A batch type wet dispersion apparatus that performs dispersion by rotating a rotary dispersion means in a vessel, characterized by having an inner lid between the top of the rotary dispersion means and an upper lid at the top of the dispersion device. Batch type wet dispersion equipment. (2) The batch type wet dispersion apparatus according to claim 1, wherein the inner lid is provided with a positioning adjustment screw. (3) The batch type wet dispersion apparatus according to claim 1, which has a leakage prevention mechanism on the outer periphery of the inner lid. (4) In a method for dispersing an electrophotographic photoreceptor coating liquid containing a pigment or dye using a batch-type wet dispersion device in which a rotary dispersion means is disposed in a vessel, the uppermost part of the rotary dispersion means and the uppermost part of the dispersion device are 1. A method for dispersing an electrophotographic photoreceptor coating liquid, which comprises dispersing an electrophotographic photoreceptor coating liquid in a vessel by providing an inner lid between the upper lid and rotating the rotating dispersion means.