JPH01210962A - Electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to PPC? 1 relates to an electrophotographic photoreceptor useful for photographic machines, laser printers, etc.

[Prior Art] One of the characteristics required of the intermediate layer is that it does not affect the characteristics of the photoreceptor even after repeated use.

However, it is extremely difficult to obtain an intermediate layer made of only a single resin that can provide such characteristics. For this reason, methods have been proposed such as blending a conductive polymer into the intermediate layer (Japanese Patent Laid-Open No. 58-95744) and dispersing conductive pigments in the resin constituting the intermediate layer (Japanese Patent Laid-Open No. 58-93063). The photoreceptor using the method of
When repeated use cycles include charging, exposure, development, transfer, and cleaning, the photoreceptor exhibits good characteristics up to about 10,000 cycles, but sensitivity decreases when used repeatedly for more than 100,000 cycles. Alternatively, if the residual potential increases or the environment moves, the characteristics of the photoreceptor deteriorate.

Also, a method has been proposed in which a layer made of only resin is provided on a layer in which conductive pigments are dispersed in the resin that constitutes the intermediate layer, but in order to obtain a uniform film of resin, a certain thickness is required. Therefore, the characteristics of the photoreceptor become dependent on the environment.

There is also a method of covering the surface of a conductive substrate with an oxide of an element of group ■ of the periodic table (Japanese Patent Application Laid-Open No. 8O-70454), but
Group element oxides alone cause a decrease in sensitivity when repeated for more than 10,000 cycles.

In view of these circumstances, it is an object of the present invention to provide a photoconductor whose characteristics, particularly chargeability, hardly change even after repeated use.

[Structure] In order to solve the above-mentioned problem, the present inventor has been conducting research for a long time, and in order to solve this problem, titanium oxide and a group Ⅰ element oxide are used as the intermediate layer, and titanium oxide and a group It has been found that it is effective to maintain the volume of the binder resin and the volume of the binder resin at a specific ratio, leading to the present invention.

That is, the present invention provides an electrophotographic photoreceptor in which an intermediate layer is provided between a conductive support and a photoconductive layer, in which the C1 intermediate layer is made of titanium oxide, a binder resin, and an element of group Ⅰ of the periodic table. oxide, and the total volume of the inorganic material consisting of titanium oxide and the oxide of Group I elements of the periodic table is three times or less the volume of the binder resin, and the volume of only titanium oxide is the binder resin. The electrophotographic photoreceptor is characterized in that the volume of the adhesive resin is one or more times the volume of the adhesive resin.

The photoreceptor of the present invention is composed of a conductive substrate, an intermediate layer, and a photosensitive layer in this order. Conductive substrates include metals such as aluminum, nickel, and stainless steel, plastics in which conductive pigments such as carbon are dispersed, and insulating supports (such as plastics or plastic films) on which metal is vapor-deposited or conductive paint is coated. An example is something that has been modified.

It is known that an intermediate layer in which titanium oxide is dispersed is provided between a conductive substrate and a photosensitive layer, but titanium oxide (P)
It has been found that when the ratio P/R of the binder resin (R) and the binder resin (R) is set to a volume ratio of 1 or more, the photoreceptor characteristics become less dependent on humidity and the photosensitivity is further improved. However, when a photoreceptor is used more than 100,000 times, its characteristics deteriorate, particularly its charging properties. The present invention is aimed at suppressing this deterioration in chargeability, and an intermediate layer made of titanium oxide, a binder resin, and an oxide of an element of Group I of the periodic table is provided on a conductive substrate. In the case where the volume of the inorganic substance consisting of titanium oxide and an oxide of a group Ⅰ element of the periodic table is 3 times or less the volume of the binder resin, and the volume of titanium oxide alone is 1 times or more the volume of the binder resin. It is characterized by certain things.

When the volume of the inorganic material consisting of titanium oxide and oxides of group Ⅰ elements of the periodic table becomes three times or more the volume of the binder resin, the intermediate layer has a large amount of space, which makes it difficult to coat the photoconductive layer. When dried, the air contained in the intermediate layer expands, creating bubbles in the photoconductive layer, which is undesirable.

Titanium oxide used in the present invention has a larger refractive index than other white pigments, is chemically and physically stable, has a large hiding power, and has a high degree of whiteness. Further, there are two types of titanium oxide: rutile type and anatase type, and either type can be used.

As the binder resin, a resin having high solvent resistance to common organic solvents is preferable, considering that a photosensitive layer is coated thereon. From this, water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon, and alkoxymethylated nylon, and curable resins such as polyurethane, melamine resin, acrylic resin, alkyd resin, and epoxy resin. can be used.

The oxide of group Ⅰ elements of the periodic table used in the present invention is BeO
, CaOlMgO, 5rO1BaO, etc. The ratio of titanium oxide to oxides of Group I elements of the periodic table is titanium oxide 1
00 parts by weight, the oxide of group Ⅰ elements of the periodic table is 1 to 1
It is preferably about 0.00 parts by weight.

The photoconductive layer used in the present invention includes: (1) one in which an electron-4I transfer complex is formed by a combination of an electron-donating compound and an electron-accepting compound (described in UPS3484237);
(2) Organic photoisoelectric material sensitized by adding dye (described in JP-A-4G-25ESG@publication); (3) Pigment dispersed in a hole- or electron-active matrix (JP-A-47) -30328, JP-A No. 47-18545), (4) functionally separated charge generation layer and 7U charge transport layer (described in JP-A-49-105537), (5) ) The main component is a eutectic chain consisting of a dye and a resin (described in JP-A-47-10785)
, (6) A photoconductor formed of any conventionally known organic photoconductor, such as a charge transfer complex containing an inorganic pigment or an inorganic charge generating material (described in JP-A No. 49-91648). It doesn't matter if you stay there.

However, among these, the laminated photoreceptor of type (4) is especially advantageous because it has high sensitivity and can be selected from a variety of materials depending on the function.

The charge-generating layer is made of polyester, charge-generating substances such as azo pigments, phthalocyanine pigments, square pigments, indigo pigments, perylene pigments, selenium powder, selenium alloy powder, amorphous silicon powder, zinc oxide powder, and cadmium sulfide powder. It is formed by dispersing in a solution of a binder resin such as polycarbonate, polyvinyl butyral, or acrylic resin, and coating this on the intermediate layer. The appropriate thickness of the charge generation layer is about 0.01 to 2 μl.

The charge transport layer is an α-phenylstilbene compound (Japanese Patent Application Laid-open No.
8-198043), hydrazone compounds (
A charge transporting substance such as JP-A No. 55-467GO) is dissolved in a film-forming resin such as polyester, polysulfone, polycarbonate, polymethacrylic acid ester, polystyrene, etc., and this is applied onto the charge generation layer. It may be applied to a thickness of about 10 to 30 μm. The film-forming resin is used here because the charge transporting substance generally has a low molecular weight and has poor film-forming properties by itself.

The photoreceptor thus produced is suitable for repeated use;
If necessary, a protective layer similar to the conventional one can be provided on the surface of the photosensitive layer.

・Example 1 Oil-free alkyd resin, Bellacolite M6401
(Solid content 50vL96) Made by C Dainippon Ink Chemical ■] 30 parts by weight, melamine resin Super Beckamine G-8
21 (solid content 60wt%) [manufactured by Dairomoto Ink Chemical ■] 1
offl parts, toluene 80 parts by weight, titanium oxide TA
-300 [manufactured by Fuji Titanium ■] 148 parts by weight, BeO powder [Kanto Kagaku ■] 1 Sffffffi part in a ball mill to 2 parts
After dispersing for 4 hours, a two-part intermediate layer coating was prepared.

This was dip-coated onto the surface of an A I drum with a diameter of 40 am and a length of 250 m, and dried at 130°C for 30 minutes to a thickness of 2.
．． An intermediate layer of 0 μm was formed.

Since the specific gravity of resin is 1.4, the specific gravity of titanium oxide is 3.9, and the specific gravity of BeO is 3.0, the volume ratio is: titanium oxide/resin-2.5/1 total inorganic substances/resin-2.8/1 Example 2 Implementation An intermediate layer was formed in the same manner as in Example 1, except that 88 parts by weight of titanium oxide TA-300 was used in Example 1.

(Volume ratio) Titanium oxide/resin - 1.5/1 Total inorganic substances/resin - 1.8/1 Comparative example 1 Example 1 except that titanium oxide TA-300 in Example 1 was changed to 20 parts. An intermediate layer was formed in the same manner as in Example 1.

(Volume ratio) Titanium oxide/resin - 0.3/1 Total inorganic substances/resin - 0.7/1 Comparative example 2 In Example 1, 200% titanium oxide TA-300
An intermediate layer was formed in the same manner as in Example 1 except that the iJQ portion was used.

(Volume ratio) Titanium oxide/resin-L4/1 Total inorganic substances/resin-3,7/1 Comparative example 3 An intermediate layer was formed in the same manner as in Example 1 except that the BeO powder was removed.

Next, polyester resin Byron 200 [manufactured by Toyobo ■]
5 parts by weight of cyclohexanone and 150 parts by weight of trisazo pigment were added and dispersed in a ball mill for 48 hours, and further 21 CHJQ parts of cyclohexanone were added and dispersed for 3 hours. Take this out into a container and the solid content is 1.5
It was diluted with cyclohexanone while stirring to give a weight percent. The charge generation layer coating solution thus obtained was dip coated onto the intermediate layer and dried at 120° C. for 5 minutes to form a charge generation layer with a thickness of about 0.2 μm.

Polycarbonate resin (Panlite K-1300 manufactured by Banjin Kasei>16) 10 parts by weight Silicone oil (K F-50 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.00
2 parts by weight of methylene chloride was dissolved in an 85-heavy dish, and the thus obtained coating solution for the transport layer was applied onto the electricity 6:f generation layer by dip coating, and dried at 120°C for 15 minutes. Then, a charge transport layer having a thickness of 20 .mu.II was formed to prepare a photoreceptor.

The characteristics of the photoreceptor thus obtained were measured using the apparatus shown in FIG. Measurement is electrification for 10 seconds and dark decay for 10 seconds.
<1) Charging potential: Potential after 10 seconds of charging. (3) Sensitivity: Defined as the amount of exposure necessary to reduce the potential to 1/2 after exposure. Further, the photoreceptor was printed with a laser printer (PC-LASEL?-8000 manufactured by Ricoh Co., Ltd.) at an amount of 150,000 rotations to give fatigue, and the photoreceptor characteristics were again determined for all J. The results are shown in Table 1.

Initial and post-fatigue images were also evaluated.

The image was taken using a laser printer (Ricoh PC-1, AS
ER-6000).

Table 1 In Comparative Example 2, bubbles were generated during the production of the photoreceptor, and the characteristics could not be measured.

Even after fatigue, the photoreceptors of Examples 1 and 2 produced good images that were the same as those at the initial stage.

In Comparative Example 1, low image density was observed after fatigue.

In Comparative Example 3, black spots occurred after fatigue.

Example 3 Alcohol-soluble copolymerized nylon CM-8000 [East ■! IR] 10 parts by weight were dissolved in 200 parts by weight of methanol, and 70 parts by weight of titanium oxide TA-300 [manufactured by Fuji Titanium] and oxides of group Ⅰ elements of the periodic table were added. A certain MgO powder [manufactured by Kamishima Chemical Industry Co., Ltd.] 10
Parts by weight were added and dispersed in a ball mill for 12 hours to prepare a coating solution for an intermediate layer.

This was applied by dip coating onto the same AI cylinder as in Example 1, and dried at 120° C. for 10 minutes to form an intermediate layer with a thickness of 3.0 μm.

Resin specific gravity 1.1, titanium oxide 3.9 Mg0 3.6, so the volume ratio is titanium oxide/resin - 2.0/1 total inorganic matter/resin - 2.3/1 Example 4 MgO powder in Example 3 was replaced with CaO powder [Manufactured by Furuuchi Kagaku ■] An intermediate layer was provided in the same manner as in Example 3 except that the amount was changed to 5 parts by weight. [Specific gravity of CaO (3,4)] (Volume ratio) Titanium oxide/resin -2,0/1 Total heat equipment/resin -2,1/1 Comparative example 4 MgO powder in Example 3 was replaced with zinc sulfide powder [Island] Manufactured by Hisa Pharmaceutical Co., Ltd.]
An intermediate layer was provided in the same manner as in Example 3 except that the amount was changed to 30 parts by weight. (Specific gravity of ZnS 4.0) (Volume ratio) Titanium oxide/resin - 2.0/1 Total inorganic substances/resin - 2.8/1 Comparative example 5 The titanium oxide powder in Example 3 was removed and the MgO powder was used. 9
An intermediate layer was provided in the same manner as in Example 3 except that the layer was changed to 0 parts and 2 parts.

(Volume ratio) Titanium oxide/resin - ○/1 Total inorganic substances/resin - 2,8/1 Next, butyral resin (S-LEC BLS manufactured by Block Chemical ■)
3 parts by weight of cyclohexanone was dissolved in 150 parts by weight of cyclohexanone, 6 parts by weight of a bisazo pigment having the following structural formula was added thereto, the mixture was dispersed in a ball mill for 48 hours, and then 210 parts by weight of cyclohexanone was added to give 12 Spread out time. This was placed in a container, and further cyclohexanone was added so that the solid content was IwL%. The coating solution for the charge generation layer thus obtained was applied by dip coating onto the intermediate layer at 120°C.
After drying for 0 minutes, a charge generation layer having a thickness of 0.3 μm was provided.

Furthermore, a charge transport layer was provided in the same manner as in Example 1 to produce a photoreceptor. The photoreceptor characteristics were measured in the same manner as in Example 1. In addition, the photoreceptor is a laser printer (PC-LA
SER-8000)'s writing optical system using a laser beam was modified to an optical system using a halogen lamp and lens for copying machines, and the image was copied at a fatigue rate of 150,000 rotations, and the characteristics of the photoconductor were again tested. Measurements were taken.

Measurements were performed at 20° C. and 60% RH. The results are shown in Table 2.

Table 2 [Effects] As explained above, the intermediate layer is composed of titanium oxide, a binder resin, and an oxide of an element of Group ■ of the periodic table, and the intermediate layer is composed of titanium oxide and an oxide of an element of Group ■ of the periodic table. If the total volume of the inorganic material consisting of is 3 times or less the volume of the binder resin, and the volume of titanium oxide alone is 1 time or more the volume of the binder resin, the photoreceptor provided with this intermediate layer is Even when subjected to the fatigue of 150,000 rotations, the charging property does not deteriorate, and the sensitivity is high and there is little variation in sensitivity.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an apparatus for determining aP1 of the characteristics of a photoreceptor.

Claims (1)

[Claims] In an electrophotographic photoreceptor comprising an intermediate layer between a conductive support and a photoconductive layer, the intermediate layer is composed of titanium oxide, a binder resin, and an oxide of a Group II element of the periodic table, and the total volume of the inorganic substance consisting of titanium oxide and an oxide of a Group II element of the periodic table is three times or less the volume of the binder resin,
An electrophotographic photoreceptor characterized in that the volume of titanium oxide alone is one or more times the volume of a binder resin.