JPH01266550A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To always maintain formation of high-quality images by incorporating a specified compound in a photosensitive layer. CONSTITUTION:The photosensitive layer contains the compounds represented by formula I and II in which X1 is trimethylmethyl, or dimethylethylmethyl; X2 is H, 1-10C alkyl or 2-10C alkenyl; each of X3 and X4 is 1-10C alkyl or 2-10C alkenyl. They are used in total in an amount of 0.5-20wt.%, preferably, 2-15wt.% of the total weight of the photosensitive layer, and in a mixing ratio of 0.1:1-1:0.1, preferably, 0.3:1-1:0.3, thus permitting the obtained photosensitive body to prevent deterioration due to active materials, such as ozone, to enhance potential stability under an environment of corona discharge and to always form stable high-quality images.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a photosensitive layer with excellent durability and no deterioration in image quality due to repeated use.

[Conventional technology]

In recent years, many electrophotographic photoreceptors using organic compounds as photoconductors have been developed. Most of those that have been put into practical use have a form in which the photoconductor is functionally separated into a charge-generating material and a charge-transporting material.

Electrophotographic photoreceptors using such organic photoconductors are expected to further improve electrophotographic properties such as sensitivity and photoresponsiveness due to the flexibility of material design, and are easy to form into films and have high productivity. It is characterized by this.

An electrophotographic photoreceptor is repeatedly subjected to various image forming processes in an electrophotographic apparatus, and during this process, the photoreceptor is required to exhibit stable characteristics. However, electrophotographic photoreceptors using organic photoconductors as described above have the disadvantage that, after repeated use, image quality deterioration such as a decrease in image density due to a decrease in charging ability and image blurring due to a decrease in surface resistance is likely to occur. be.

The cause of these deteriorations is thought to be largely influenced by corona discharge. That is, when a photoreceptor is used in a copying machine, it is constantly exposed to an atmosphere of corona discharge, and as copies are repeatedly made, organic light is emitted by active substances such as ozone, NO, and nitric acid generated by corona discharge. It is thought that the conductor is subject to deterioration. In particular, electrophotographic photoreceptors using organic photoconductors are often used with negative charging, but in the case of negative corona charging, the amount of ozone generated is greater than that of positive charging. This is one of the factors that makes it more susceptible to deterioration than other photoreceptors.

In addition, after copying is completed, the part of the photoreceptor directly below the corona charger that has stopped rotating deteriorates, and the charging ability of that part deteriorates significantly, a phenomenon called dormant memory. considered to be an influence.

Conventionally, methods for preventing such deterioration of electrophotographic photoreceptors have been disclosed in Japanese Patent Application Laid-open Nos. 57-122444 and 1983.
Various additives such as antioxidants, ultraviolet absorbers, and photodegradation inhibitors are added as described in JP-A No. 8-120260, JP-A-61-156131, JP-A-62-105151, etc. It is proposed to do so.

However, none of these methods can be said to be practically sufficient against deterioration of electrophotographic photoreceptors, and the dark potential (Vo)
That is, it is insufficient to suppress a decrease in charging potential.

Additionally, when additives are added, the additive itself acts as a trapping agent for charge transfer, causing an increase in bright area potential (VL), which can actually worsen electrophotographic properties. be.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an electrophotographic photoreceptor that prevents deterioration caused by active substances such as ozone, No. 2, and nitric acid, and does not cause any adverse effects on electrophotographic properties.

A further object of the present invention is to provide an electrophotographic photoreceptor that has high potential stability (and can always maintain high quality images) even after repeated use.

[Means for solving problems]

The present inventors investigated the factors of such photoreceptor deterioration, and
As a result of repeated studies on improvement methods, we found that adding at least two specific types of compounds to the photosensitive layer containing an organic photoconductor has a sufficient effect of preventing deterioration and also improves other electrophotographic properties. It was discovered that a photoreceptor without any harmful effects can be obtained, and the present invention was completed.

That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, wherein the photosensitive layer has at least the general formula (I), and X2 is H1 having 1 to 10 carbon atoms. It represents an alkyl group or an alkenyl group having 2 to 10 carbon atoms. ] and General Formula (II) [However, X3 and x4 represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms. ] An electrophotographic photoreceptor characterized by containing a compound represented by the following.

The present invention also provides an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, wherein the photosensitive layer has the general formula (1), and X2 is H1 having 1 to 10 carbon atoms. It represents an alkyl group or an alkenyl group having 2 to 1.0 carbon atoms. ] and General Formula (II) [However, X3 and x4 represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms. ] and general formula (III) R.

CHCH2C00Cn H2n+ 1 / \ CHCH2C00Cni H2m+1 [However, n and m represent integers of 10 to 20, and R1
and R2 represents H or an alkyl group having 1 to 1 o carbon atoms. ] An electrophotographic photoreceptor characterized by containing a compound represented by the following.

The present invention will be explained in detail below.

The additive in the present invention is a phenol derivative having three hindered phenol groups, which is known as a radical scavenger or antioxidant for plastics, rubber, etc.
Phosphites known as hydroperoxide decomposers are used at the same time.

The mechanism of preventing deterioration by using these two types of compounds at the same time is currently unclear, but it may be due to the interaction between the hindered phenol group and the phosphite group, or due to ozone and the accompanying active substances. It is believed that this has a synergistic effect on preventing deterioration of the photosensitive layer.

The compound represented by the general formula (I) in the present invention includes 1,3.5-)listyl-2,4,6-)lithyl-(3
, 5-di-t-butyl-4-hydroxybenzyl)benzene, 1,3.5-)dimethyl-2,4,6-dolisu(3,5-di-t-amyl-4-hydroxybenzyl)benzene, 1,3,5-trimethyl-2,4,6-)
Lis-(3-t-butyl-5-methyl-4-hydroxybenzyl)benzene, 1,3.5-trimethyl-2゜4
．． 6-Dolisu(3-t-amyl-5-isopropyl-
4-hydroxybenzyl)benzene, 1,3.5-trimethyl-2,4,6-)lis-(3-t-amyl-5-
(1-butenyl)-4-hydroxybenzyl)benzene, etc. In particular, X2 in general formula (I) is preferably an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. .

Further, as the compound represented by the general formula (II) in the present invention, tris(2,4-di-t-butylphenyl)-
Phosphite, tris(2,4-di-t-acylphenyl)-phosphite, tris(2-t-7'thyl-4-
methylphenyl) phosphite, tris(2-ethyl-
4-methylphenyl) phosphite, tris(2-t-
Examples include amyl-4-(l-butenyl)phenyl)phosphite, and in particular, X3 and X4 in general formula (II) are an alkyl group having 1 to 5 carbon atoms, or
~5 alkenyl groups are preferred.

The total amount of these compounds added is in the range of 0.5 to 20%, preferably 2 to 15%, based on the total weight of the photosensitive layer, and the mixing ratio is 0.1:1 to 1:O. , l, preferably in the range of 0.3:1-1:0.3.

If the total amount added is less than 0.5%, the deterioration prevention effect will be insufficient, and if it exceeds 20%, problems such as decreased sensitivity and increased residual potential will likely occur.

In addition, in the present invention, the two types of compounds described above include
By adding a sulfide compound represented by the general formula (III), which is known as a hydroperoxide decomposer, even more outstanding effects can be achieved.

Specific examples of the compound represented by the general formula (III) include dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, and simiristyl-3,3'-thiodipropionate. Dipropionate, lauryl-stearyl-3,3'-thiodipropionate, distearyl-3,3'-methyl-3゜3'
-thiodipropionate, distearyl-3-ethyl-
Examples include 3'-methyl-3,3'-thiodipropionate, and in particular, n and m in general formula (III) are integers of 12 to 18, and R1 and R2 have 1 to 18 carbon atoms. The alkyl group of 4 is preferred.

The amount added may be within the range of the total amount added above.

The photosensitive layer containing an organic photoconductor in the present invention is a single-layer photoconductor in which a charge-generating material and a charge-transporting material are mixed in a functionally separated manner, or a charge-generating layer containing a charge-generating material and a charge-transporting material. It takes the form of a laminated photoreceptor, etc., in which a charge transport layer containing a laminate is laminated.

Examples of charge-generating materials include pyrylium, thiopyrylium dyes, phthalocyanine pigments, anthoanthrone pigments,
Organic photoconductors such as perylene pigments, dibenzpyrenequinone pigments, pyranthrone pigments, azo pigments, indigo pigments, and quinacridone pigments are used.

As charge transport materials, pyrazoline type, hydrazone type,
Stilbene type, triphenylamine type.

Benzidine series, oxazole series, indole series.

Organic photoconductors such as carbazole compounds are used.

In the case of a single-layer type photoreceptor, the charge-generating material and charge-transporting material described above are dissolved or dispersed in a suitable binder resin, and a layer is formed on the conductive support by coating. On the other hand, as a laminated type,
1) Charge generation layer on the conductive support.

There are two types: one in which a charge transport layer is laminated in this order, and the other in which (2) a charge transport layer and a charge generation layer are laminated in this order. In the case of (2), the charge generation layer can be formed by dispersing or dissolving the charge generation material in a binder resin and a solvent, or by vapor deposition.
There are methods such as sputtering.

The film thickness is preferably 5 μm or less, particularly 0.01 to 3 μm. In this case, an inorganic photoconductor such as selenium or amorphous silicon can also be used.

The charge transport layer is formed by dissolving the above-mentioned charge transport material in a binder resin having film-forming properties and laminating it on the charge generation layer. Film thickness is 5-4
0 μm, especially 8 to 35 μm is preferred.

In this case, the additive of the present invention is preferably included in the charge transport layer.

On the other hand, when a charge generation layer is laminated on the charge transport layer, both layers can be formed by applying the above-mentioned organic photoconductor together with a binder resin. At this time, it is preferable that a charge transport material is also contained in the charge generation layer. In this case, the additive is preferably contained in the charge generation layer or both the charge generation layer and the charge transport layer.

Examples of the conductive support include known ones, such as cylindrical or belt-shaped aluminum, iron, copper, or metal-deposited plastic films. Further, an intermediate layer such as an adhesive layer, a barrier layer, a smooth layer, etc. may be provided between the support and the photosensitive layer, if necessary.

The electrophotographic photoreceptor of the present invention can be applied to photoreceptors of various devices to which electrophotography is applied, such as ordinary copying machines, laser beam printers, LED printers, LCD printers, and CRT printers.

〔Example〕

Next, the present invention will be specifically explained using examples.

Example 1 Conductive support with a diameter of 80 mm and a length of 360 m
A 5% methanol solution of polyamide resin (trade name: Amilan CM-8000, manufactured by Toshi) was applied to the aluminum cylinder by dipping to form a 0.5 μm thick undercoat layer.

Next, 10 parts (by weight, the same applies hereinafter) of a trisazo pigment having the following structural formula were added to polyvinyl butyral resin (S-LEC BL-S).

(manufactured by Miki Kagaku) and 50 parts of cyclohexanone were dispersed using a sand mill device using glass beads.

100 parts of methyl ethyl ketone was added to this dispersion and applied onto the undercoat layer to form a charge generation layer with a thickness of 0.2 μm.

Next, 10 parts of a stilbene compound having the following structural formula and 10 parts of polycarbonate resin (Panlite L-1250 manufactured by Ondai Kasei) were dissolved in 50 parts of dichloromethane and 10 parts of monochlorobenzene to prepare a charge transport layer coating solution. This was added to 1,3,5-trimethyl-2,4,6-)lis-(3,5-di-t-butyl-4
-hydroxybenzyl)benzene (THBZ-1) + (
Product name IRGANOX1330: manufactured by Ciba Geigy Japan) and tris(2,4-di-t-butylphenyl)-
Phosphite (TBP-1): (IRGAFO3168: manufactured by Ciba Geigy, Japan) added at a mixing ratio of 1:1 with 0.4 parts and 2 parts, respectively; added at a mixing ratio of 0.5:1 as described above; Also, using the mixture added as described above at a mixing ratio of 1:0.5,
It was coated on the charge generation layer to form a charge transport layer with a thickness of 18 μm. The photoreceptors manufactured in this way were each photoreceptor 1. 2. 3. 4. 5 and 6.

Furthermore, as a comparative sample, photoreceptor 7 without additives
, photoreceptor 8 to which 0.4 parts and 2 parts of THBZ-1 were added alone
, 9, and 0.4 parts of TBp-7 alone.

2 parts plus photoreceptor 10. 11 were produced respectively.

These photoreceptors were installed in an electrophotographic copying machine, and their characteristics were evaluated as follows. First, the dark potential (VO) of the photoreceptor,
Bright area potential (VL) is -650V.

The conditions for the latent image were set to -150V.

The image exposure amount at that time was determined and used as the initial sensitivity. Next 5.0
After continuous copying of 00 sheets, the potential was measured, and the rate of decrease in vo and the increase in vL were determined. Thereafter, the photoreceptor was left in a copying machine, and the surface potential was measured after 10 hours. At this time, mark the part of the photoreceptor that was located directly under the corona charger while it was left to stand, and check the difference (△VO) from other parts.
I asked for

Furthermore, 5,000 sheets were continuously copied (total of 10,000 copies)
00 copies) The same measurements as above were performed. The part of the photoreceptor located directly under the corona charger is made to be the same as in the case of 5,000 sheets. These results are shown in Table 1.

Further, photoreceptors were manufactured with various additive mixing ratios and amounts added, and similar evaluations were conducted. The results are shown in Table 2. The amounts added in the table are based on the added photosensitive layer, that is,
Here, it is the weight ratio to the weight of the charge transport layer.

As is clear from Tables 1 and 2, the photoreceptor containing the two types of additives of the present invention in the photosensitive layer shows a small decrease in dark area potential (resistance to deterioration) in repeated electrophotographic processes. It has an excellent prevention effect, and the deterioration of the part immediately below the corona charger is extremely small.Additionally, there is no adverse effect on electrophotographic properties such as an increase in bright area potential due to the addition of additives.

On the other hand, in a photoreceptor that does not contain additives, a significant decrease in dark area potential is observed due to deterioration, and the portion directly below the corona charger is also severely deteriorated. Furthermore, when one of these is added, the deterioration is somewhat improved compared to a photoreceptor in which no addition is made, but it cannot be said to be sufficient compared to the present invention.

Example 2 As a charge-generating material, 10 parts of a disazo pigment having the following structural formula, 6 parts of polyvinyl butyral resin (Eslec BX-1, manufactured by Block Chemical Co., Ltd.), and 50 parts of cyclohexanone were dispersed in a sand mill device using glass beads. 100 parts of tetrahydrofuran was added to this dispersion, and the mixture was coated on the same conductive support and undercoat layer as in Example 1 to form a charge generation layer with a thickness of 0.2 μm.

Next, as a charge transport material, 8 parts of a benzcarbazole compound having the following structural formula, 10 parts of a styrene-acrylic copolymer resin (Estyrene MS-200, Nippon Steel Chemical System), 1,3.5-)limethyl-2,4゜6−
Dolis(3,5-di-t-amyl-5-hydroxybenzyl)benzene (THBZ-2): and tris(2
,4-di-t-amylphenyl)-phosphite (TB
P-2): A solution prepared by dissolving 0.72 parts of P-2) in 15 parts of dichloromethane and 45 parts of monochlorobenzene at a mixing ratio of 1:1 was applied onto the charge generation layer to form a charge transport layer with a thickness of 18 μm. This will be referred to as a photoreceptor 19.

On the other hand, for comparison, a photoreceptor 20 to which THBZ-2 and TBP-2 were not added was manufactured. Furthermore, as a comparison sample, the additives shown in Table 3 were used alone or in combination (mixing ratio 1/1).
The photoreceptor used in Example 1 was manufactured in the same manner.

Table 3 Characteristics of these photoreceptors were evaluated in the same manner as in Example 1. Also, early ■. , vL respectively -650V
, the amount of light when setting the voltage to -150V was also measured.

These results are shown in Table 4.

As shown in Table 4, the photoreceptor containing the additive of the present invention has small potential fluctuations (and is excellent in preventing deterioration).On the other hand, other additives or different combinations do not have sufficient deterioration prevention effect. It turns out that either there is no benefit, or the harm is significant.

Example 3 A subbing layer was coated on a conductive support in the same manner as in Example 1. Next, a solution prepared by dissolving 15 parts of a stilbene compound of the following structural formula and 10 parts of polycarbonate resin (Panlite L-1250 manufactured by Kijin Kasei) in 50 parts of dichloromethane and 10 parts of monochlorobenzene was applied onto the undercoat layer, and a charge of 15 μm thickness was applied. A transport layer was formed.

Next, 4 parts of the disazo pigment having the following structural formula, 7 parts of the above stilbene compound, 10 parts of the above polycarbonate resin, THBZ-1, TBP-
A paint obtained by dispersing and dissolving 0.63 parts of 1/1 mixture in 150 parts of dichloromethane and 50 parts of monochlorobenzene was spray coated on the charge transport layer to form a charge generation layer with a thickness of 5 μm. This will be referred to as a photoreceptor 35.

On the other hand, photoreceptor 3 without adding THBZ-1/TBP-1
6 was manufactured.

These photoreceptors are positively charged to V. =+650V.

The setting was made so that VL=+150V, and the following evaluations were conducted in the same manner as in the conventional case. The results are shown in Table 5.

Example 4 A subbing layer was coated on a conductive support in the same manner as in Example 1.

Next, 1 part of a disazo pigment having the following structural formula, 10 parts of the benzcarbazole compound used in Example 2, 10 parts of polycarbonate resin (Panlite L-1250 manufactured by Ondai Kasei), 1,3.5-trimethyl-2,4 , 6-dolisu(3-t-amyl-5-t
-butyl-4-hydroxybenzyl)benzene (THB
Z-3): and tris(2-t-amyl-4-t-butylphenyl)-phosphite (TBP-3): 0.3 parts at a mixing ratio of 1/l, 60 parts of dichloromethane, and 20 parts of monochlorobenzene. The coating solution dispersed and dissolved in the above-mentioned undercoat layer was applied onto the undercoat layer to produce a photosensitive layer with a thickness of 16 μm. This is photoreceptor 3
Set it to 7. On the other hand, for comparison, THBZ-3/TBP-3
A photosensitive layer without the addition of is produced, and this is used as a photoreceptor 38. These photoreceptors were evaluated in the same manner as in Example 3, and the results are also listed in Table 5.

Table 5 Example 5 Compounds shown in Table 6 were used as additives at a mixing ratio of 1/l,
A photoreceptor was produced in the same manner as in Example 1 except for the addition amount of 10%. These results are shown in Table 7.

Example 6 1,3.5-trimethyl-2,4,6- as an additive
Tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene (THBZ-1), tris(2,4-di-t-butylphenyl)phosphite (TBP-1),
and distearyl-3,3'-thiodipropionate (TP-1): C) I2CH2COOC,8H.

/ \ CH2CH2C00C18H3? A photoreceptor 48 was produced in the same manner as in Example 1, except that Sumilizer TPS (manufactured by Sumitomo Chemical Industries, Ltd.) was used, the mixing ratio was 1:1:2, and the amount added was 10%.

In addition, TP-1 was converted to similystyl-3,3'-thiodipropionate (T
P-2) :C1]2CH2COOC14H2゜/ ＼ CH2CH2C00C34H2゜ (Sumilizer TPM: manufactured by Sumitomo Chemical Industries) and lauryl-stearyl-3,3'-thiodipropione) (TP-3): CH2CH2C0oC22H2゜/ ＼ CH2CH2C00Css H37( Cyarox12
12: Photoreceptor 49.50 was manufactured in the same manner except that the photoreceptor was replaced with (manufactured by ACC).

These photoreceptors were evaluated in the same manner as in Example 1. The results are shown in Table 8. Also, for comparison, THBZ-
Table 8 also shows the evaluation results of Photoreceptor 2 to which two types of compounds, TP-1 and TBP-1, were added, Photoreceptor 7 to which no additive was added, and Photoreceptor 51 to which only 10% of TP-1 was added.

As described above, by adding a specific additive to the two types of additives according to the present invention, the decrease in dark potential can be further reduced, and the deterioration of the portion immediately below the corona charger can be further reduced.

Example 7 Photoreceptors manufactured in Examples 1 and 2 2.7. 19. Regarding the photoreceptor 48 manufactured in Example 6, after 10,000 copies in the characteristic evaluation described above, an additional 40.0
00 copies were made. As a result, for photoreceptors 2, 19, and 48 to which additives were added, even after 50,000 sheets of printing, there was no deterioration in image quality compared to the initial stage, and images with stable high contrast and no unevenness were obtained. On the other hand, in the photoreceptor 17 to which no additives were added, the image density decreased significantly after around 15,000 sheets. Furthermore, due to the potential drop that occurs when the printer is left at rest after copying, the image becomes extremely uneven.

〔Effect of the invention〕

As explained above, according to the present invention, which is a photoreceptor containing a combination of specific additives, deterioration of the photoreceptor due to active substances such as ozone can be prevented without adversely affecting electrophotographic characteristics. It has excellent potential stability in a corona discharge environment and can always form stable, high-quality images.

Claims (4)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, the photosensitive layer has at least the general formula (I) ▲Mathematical formula, chemical formula, table, etc.▼ ▲Mathematical formula, chemical formula , tables, etc. ▼ [However, for X_1 ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ where X_2 represents H, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. ] and General Formula (II) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [However, X_3 and X_4 represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms. ] An electrophotographic photoreceptor characterized by containing a compound represented by the following. (2) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer. (3) In an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, the photosensitive layer has the general formula (
I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [However, for X_1, ▲There are mathematical formulas, chemical formulas, tables, etc.▼
or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ where X_2 represents H, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. ] and General Formula (II) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [However, X_3 and X_4 represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms. ] and general formula (III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [However, n and m represent integers from 10 to 20, and R_
1 and R_2 represent H or an alkyl group having 1 to 10 carbon atoms. ] An electrophotographic photoreceptor characterized by containing a compound represented by the following. (4) The electrophotographic photoreceptor according to claim 3, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.