JP2010230746A - Monolayer electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monolayer electrophotographic photoreceptor which effectively suppresses the occurrence of a back spot in a high-temperature high-humidity environment, while effectively holding superior sensitivity characteristics, even in a high-temperature high-humidity environment, and to provide an image forming apparatus which uses the same. <P>SOLUTION: The monolayer electrophotographic photoreceptor includes an intermediate layer and a photosensitive layer on a substrate, and the image forming apparatus uses this photoreceptor. The intermediate layer contains a binder resin and titanium oxide fine particles, and the titanium oxide fine particles have the characteristics: (a) a number average primary particle size of the titanium oxide fine particles is within a range of 5 to 30 nm; (b) the titanium oxide fine particles are subjected to surface treatment with alumina and silica; and organic silicon compound, and (c) a weight ratio X (wt.%) of the organic silicon compound on surfaces of the titanium oxide fine particles satisfies formula (1): 1(wt.%)≤X<4 (wt.%). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a single layer type electrophotographic photosensitive member and an image forming apparatus. In particular, it is possible to effectively suppress the generation of black spots in a high-temperature and high-humidity environment, and use a single-layer electrophotographic photosensitive member that can effectively maintain excellent sensitivity characteristics even in a low-temperature and low-humidity environment. The present invention relates to an image forming apparatus.

In recent years, organic photoconductors are often used as electrophotographic photoconductors used in electrophotographic machines such as copying machines and laser printers because of demands for low cost and low environmental pollution.
As such an organic photoreceptor, a multilayer electrophotographic photoreceptor obtained by laminating a charge generation layer and a charge transport layer and a single layer type electrophotographic photoreceptor comprising a single layer are known.
Among these, the single-layer type electrophotographic photosensitive member has a simple structure as compared with the laminated type electrophotographic photosensitive member, so that it is easy to produce and advantageous in terms of cost.
In addition, unlike the multilayer electrophotographic photosensitive member, it is advantageous in that it can be configured as a positively charged electrophotographic photosensitive member to suppress generation of oxidizing gas during use.

However, even when a single-layer electrophotographic photosensitive member is used, for example, when high-speed image formation is performed such that the drum peripheral speed exceeds 100 mm / sec, the influence of the oxidizing gas becomes large. The surface of the photosensitive layer tends to deteriorate.
Further, filming due to residual toner tends to occur on the surface of the photosensitive layer.
As a result, the pressure resistance of the photosensitive layer is likely to be excessively lowered, and therefore, a leak current is likely to occur particularly in a high-temperature and high-humidity environment, and a black spot is likely to occur in the formed image.

Therefore, a method of providing an intermediate layer between the substrate and the photosensitive layer is widely used as a method for solving such a decrease in pressure resistance.
However, when the intermediate layer is provided, the charge mobility in the photosensitive layer is likely to be lowered, and thus there has been a problem that it is difficult to obtain sufficient sensitivity characteristics particularly in a low temperature and low humidity environment.

Thus, a single-layer electrophotographic photosensitive member is disclosed in which predetermined fine particles are contained in the intermediate layer in order to obtain sufficient sensitivity characteristics in a low temperature and low humidity environment even when the intermediate layer is provided. (For example, Patent Documents 1 and 2).
That is, in Patent Document 1, titanium oxide fine particles are contained in the intermediate layer, and the average primary particle diameter of the titanium oxide fine particles is a value in the range of 10 to 30 nm. And a monolayer type electrophotographic photosensitive member that has been surface-treated with an organosilicon compound and the weight ratio of the organosilicon compound on the surface of the titanium oxide fine particles is a value within the range of 4 to 9.5 wt%. Has been.

  Patent Document 2 discloses an intermediate layer containing titanium oxide fine particles that have been surface-treated with alumina, silica, and an organosilicon compound, and a contact potential difference with respect to an aluminum deposition surface is 0 V or more and 0.6 V or less. An electrophotographic photosensitive member having an intermediate layer having a value of is disclosed.

JP 2007-286484 A (Claims) JP 2002-287396 A (Claims)

However, the single-layer electrophotographic photosensitive member disclosed in Patent Document 1 has succeeded in suppressing changes in sensitivity characteristics before and after performing durable printing in a low-temperature and low-humidity environment. Due to the excessively large weight ratio of the organosilicon compound, the initial sensitivity characteristic itself is insufficient.
In addition, regarding the electrophotographic photosensitive member disclosed in Patent Document 2, not only the particle diameter of the titanium oxide fine particles may be excessively large but also the important proportion of the organosilicon compound in the titanium oxide fine particles may be excessively large. There is a problem that it is difficult to stably obtain a sufficient initial sensitivity.
Therefore, there is a need for a single-layer electrophotographic photosensitive member that can effectively suppress the generation of black spots in a high-temperature and high-humidity environment, but can effectively maintain excellent sensitivity characteristics even in a low-temperature and low-humidity environment. It was.

Therefore, as a result of intensive studies, the present inventors have provided an intermediate layer between the substrate and the photosensitive layer in the single layer type electrophotographic photosensitive member, and specific titanium oxide fine particles are provided on the intermediate layer. It has been found that the above-mentioned problems can be solved by the inclusion.
That is, an object of the present invention is to provide a single-layer electrophotographic film that can effectively suppress the generation of black spots in a high-temperature and high-humidity environment, but can effectively maintain excellent sensitivity characteristics even in a low-temperature and low-humidity environment. It is an object to provide a photoreceptor and an image forming apparatus using the same.

According to the present invention, there is provided a single-layer electrophotographic photosensitive member having an intermediate layer and a photosensitive layer on a substrate, the intermediate layer containing a binder resin and titanium oxide fine particles. The titanium oxide fine particles have the following characteristics (a) to (c), and a single layer type electrophotographic photosensitive member is provided, which can solve the above-mentioned problems.
(A) The number average primary particle diameter of the titanium oxide fine particles is a value within a range of 5 to 30 nm.
(B) Titanium oxide fine particles are surface-treated with alumina, silica and an organosilicon compound.
(C) The weight ratio X (wt%) of the organosilicon compound on the surface of the titanium oxide fine particles satisfies the following relational expression (1).
1 (% by weight) ≦ X <4 (% by weight) (1)
That is, since the intermediate layer contains titanium oxide fine particles having a predetermined particle diameter and a predetermined surface treatment, the intermediate layer is imparted with a uniform and suitable conductivity. can do.
Therefore, the balance between the pressure resistance of the photosensitive layer and the charge mobility can be improved, and as a result, generation of black spots in a high temperature and high humidity environment can be effectively suppressed, while in a low temperature and low humidity environment. However, excellent sensitivity characteristics can be effectively retained.

In constituting the single-layer electrophotographic photosensitive member of the present invention, the photosensitive layer preferably contains titanyl phthalocyanine crystals having the following characteristics (A) and (B) as charge generating agents.
(A) In a CuKα characteristic X-ray diffraction spectrum, it has a main peak at a Bragg angle of 2θ ± 0.2 ° = 27.2 °.
(B) In differential scanning calorimetry, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
By comprising in this way, the outstanding sensitivity characteristic can be more effectively hold | maintained even in a low-temperature, low-humidity environment.

In constituting the single-layer electrophotographic photosensitive member of the present invention, it is preferable that a surface treatment with an organosilicon compound is performed on the surface treatment layer with alumina and silica.
By comprising in this way, more uniform and more suitable electroconductivity can be provided with respect to an intermediate | middle layer.

In constituting the single layer type electrophotographic photosensitive member of the present invention, the content of the titanium oxide fine particles is set to a value within the range of 120 to 450 parts by weight with respect to 100 parts by weight of the binder resin of the intermediate layer. It is preferable.
By comprising in this way, more uniform and more suitable electroconductivity can be provided with respect to an intermediate | middle layer.

In constituting the single-layer electrophotographic photosensitive member of the present invention, the binder resin of the intermediate layer is preferably a polyamide resin.
By comprising in this way, the adhesiveness of a base | substrate and a photosensitive layer can also be improved effectively, improving the dispersibility of the titanium oxide microparticles | fine-particles in an intermediate | middle layer.

In constituting the single layer type electrophotographic photosensitive member of the present invention, the thickness of the intermediate layer is preferably set to a value in the range of 0.1 to 50 μm.
By comprising in this way, the electroconductivity of an intermediate | middle layer can be made into a more uniform and more suitable range.

Another aspect of the present invention includes any one of the above-described single layer type electrophotographic photosensitive members, and a charging unit, a developing unit, a transfer unit, a cleaning unit, and a cleaning unit around the single layer type electrophotographic photosensitive member. An image forming apparatus in which a charge eliminating unit is arranged.
That is, in the image forming apparatus of the present invention, since the specific single-layer electrophotographic photosensitive member described above is mounted, generation of black spots in a high temperature and high humidity environment can be effectively suppressed, Even under a low humidity environment, excellent sensitivity characteristics can be effectively retained.

In configuring the image forming apparatus of the present invention, the cleaning unit is preferably a cleaning unit that employs a roller cleaning system that polishes the surface of the single-layer electrophotographic photosensitive member with a roller member.
With this configuration, it is possible to effectively retain the pressure resistance of the photosensitive layer by polishing and removing the portion of the surface of the photosensitive layer that has been oxidized and deteriorated or the portion where the residual toner has filmed.

In constituting the image forming apparatus of the present invention, it is preferable that the charging unit is a charging unit that charges the surface of the single-layer electrophotographic photosensitive member to a positive polarity.
By comprising in this way, compared with the negative polarity type, it is possible to suppress oxidative deterioration of the photosensitive layer due to an oxidizing gas such as ozone. Even in a high humidity environment, the generation of black spots can be more effectively suppressed.

In configuring the image forming apparatus of the present invention, it is preferable to set the peripheral speed of the single-layer electrophotographic photosensitive member to a value of 100 mm / sec or more.
With this configuration, oxidation deterioration on the surface of the photosensitive layer and filming due to residual toner are likely to occur, and the pressure resistance of the photosensitive layer is likely to be reduced. Even in a high humidity environment, the generation of black spots can be effectively suppressed.
Moreover, even in a low-temperature and low-humidity environment, excellent sensitivity characteristics that can cope with such high speed can be exhibited.

FIG. 1 is a diagram provided for explaining the basic structure of the single-layer electrophotographic photosensitive member of the present invention. FIG. 2 is a diagram provided to explain the relationship between the weight ratio of the organosilicon compound on the surface of the titanium oxide fine particles, the sensitivity characteristics in a low temperature and low humidity environment, and the occurrence of black spots in a high temperature and high humidity environment. FIG. 3 is a diagram provided to explain the relationship between the type of charge generating agent and the sensitivity characteristics in a low-temperature, low-humidity environment. FIG. 4 is a diagram provided for explaining the basic configuration of the image forming apparatus of the present invention. FIG. 5 is a CuKα characteristic X-ray diffraction spectrum of the titanyl phthalocyanine crystal used in Example 6 (after storage in tetrahydrofuran for 24 hours). FIG. 6 is a differential scanning calorimetry chart of the titanyl phthalocyanine crystal used in Example 6.

[First Embodiment]
The first embodiment is a single-layer electrophotographic photosensitive member provided with an intermediate layer and a photosensitive layer on a substrate, and the intermediate layer contains a binder resin and titanium oxide fine particles. In addition, a single-layer electrophotographic photosensitive member is provided in which the titanium oxide fine particles have the following characteristics (a) to (c), and the above-described problems can be solved.
(A) The number average primary particle diameter of the titanium oxide fine particles is a value within a range of 5 to 30 nm.
(B) Titanium oxide fine particles are surface-treated with alumina, silica and an organosilicon compound.
(C) The weight ratio X (wt%) of the organosilicon compound on the surface of the titanium oxide fine particles satisfies the following relational expression (1).
1 (% by weight) ≦ X <4 (% by weight) (1)
Hereinafter, the single-layer electrophotographic photosensitive member as the first embodiment will be specifically described for each component.

1. Basic Configuration The basic configuration of the single-layer electrophotographic photosensitive member of the present invention is such that an intermediate layer 16 is provided on a substrate 12 and a single photosensitive layer 14 is provided thereon as shown in FIG. This is a single layer type electrophotographic photoreceptor 10.
Here, the intermediate layer 16 can be formed by applying a coating liquid in which specific titanium oxide fine particles and a binder resin are dissolved or dispersed in a predetermined solvent on the substrate 12 and drying.
The photosensitive layer 14 is formed by applying a coating solution in which a charge generating agent, an electron transport agent, a hole transport agent, and a binder resin are dissolved or dispersed in a predetermined solvent on the intermediate layer 16 described above. Then, it can be formed by drying.
Such a single-layer type electrophotographic photoreceptor 10 is applicable to both positive and negative charge types, has a simple layer structure, and can suppress film defects when forming a photosensitive layer, so that it has excellent productivity. ing. Moreover, since there are few interfaces between layers, there exists an advantage that an optical characteristic can be improved.

2. 1. Substrate As the substrate 12 illustrated in FIG. 1, various materials having conductivity can be used. For example, metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, and plastic materials on which the above-mentioned metals are deposited or laminated And glass coated with aluminum iodide, alumite, tin oxide, indium oxide, and the like.
Further, the shape of the substrate may be any of a sheet shape, a drum shape, or the like according to the structure of the image forming apparatus to be used. The substrate itself has conductivity, or the surface of the substrate has conductivity. If you do. Further, the substrate preferably has a sufficient mechanical strength when used.

3. Intermediate Layer As illustrated in FIG. 1, the single layer type electrophotographic photosensitive member of the present invention has an intermediate layer 16 containing a binder resin and specific titanium oxide fine particles provided on a substrate 12. It is characterized by.
Hereinafter, the intermediate layer will be described separately for titanium oxide fine particles, a binder resin, and the like.

(1) Titanium oxide fine particles The intermediate layer in the present invention is characterized by containing titanium oxide fine particles.
This is because the titanium oxide fine particles have predetermined electrical characteristics, and therefore the conductivity in the intermediate layer can be adjusted to a predetermined range.
This is because it is possible to adjust the balance between the improvement in pressure resistance of the photosensitive layer and the decrease in charge mobility, which are caused by providing the intermediate layer.
In addition, as a kind of titanium oxide fine particle, both crystalline and amorphous can be used.
Further, when the titanium oxide is crystalline, any of anatase type, rutile type and brookite type can be used as the crystal type, and it is particularly preferable to use the rutile type.

(1) -1 Number average primary particle diameter The number average primary particle diameter of the titanium oxide fine particles is a value within a range of 5 to 30 nm.
This is because the dispersibility of the titanium oxide fine particles in the intermediate layer can be improved by setting the number average primary particle diameter of the titanium oxide fine particles to a value within this range.
That is, when the number average primary particle diameter of the titanium oxide fine particles becomes a value of less than 5 nm, the titanium oxide fine particles tend to be excessively aggregated or the specific surface treatment described later is uniformly applied to the titanium oxide fine particles. This is because it may be difficult. On the other hand, if the number average primary particle diameter of titanium oxide exceeds 30 nm, it is difficult to uniformly disperse in the intermediate layer, which may cause fogging in a high temperature and high humidity environment.
Therefore, the number average primary particle diameter of the titanium oxide fine particles contained in the intermediate layer is more preferably set to a value within the range of 7 to 25 nm, and further preferably set to a value within the range of 10 to 20 nm.
Further, the titanium oxide fine particles may be aggregated in a predetermined range, and the number average secondary particle diameter in that case is preferably a value in the range of 30 to 100 nm, preferably in the range of 30 to 50 nm. More preferably, the value of
Moreover, the number average primary particle diameter of the titanium oxide fine particles can be measured by combining an electron micrograph and an image processing apparatus.
In addition, the number average primary particle diameter of the titanium oxide fine particles in the present invention means the number average primary particle diameter of the titanium oxide fine particles after the surface treatment described later.

(1) -2 Surface treatment (surface treatment with alumina and silica)
Further, the titanium oxide fine particles are characterized by being surface-treated with alumina and silica.
This is because the basic dispersibility of the titanium oxide fine particles in the intermediate layer can be improved by performing a surface treatment with alumina (Al ₂ O ₃ ) or silica (SiO ₂ ).
In addition, after the surface treatment with alumina and silica is performed on the titanium oxide fine particles, the surface treatment with the organosilicon compound described later is performed, so that the weight ratio of the organosilicon compound on the surface of the titanium oxide fine particles is within a predetermined range. This is because it becomes easy to adjust to the value of.

Moreover, as a surface treatment by alumina with respect to titanium oxide fine particles, it can carry out by the following methods, for example.
First, fine particles of titanium oxide are dispersed in an aqueous solution of an aluminum salt such as aluminum chloride to obtain a dispersion. Next, an alkaline substance such as sodium hydroxide is added to the obtained dispersion to deposit aluminum hydroxide on the surface of the titanium oxide fine particles, and then ignited at a temperature of about 500 ° C. Surface treatment can be performed.

Moreover, as a surface treatment by the silica with respect to titanium oxide microparticles | fine-particles, it can carry out with the following methods, for example.
First, titanium oxide fine particles are added to water together with an alkaline substance such as sodium hydroxide to obtain an alkaline aqueous slurry. Next, by adding silica sol or an alkali silicate aqueous solution to the obtained aqueous slurry to maintain the pH of the aqueous slurry alkaline, titanium oxide fine particles having a silica coating formed on the surface can be obtained. Next, surface treatment with silica can be performed by subjecting the obtained titanium oxide fine particles to treatment such as washing and drying.

Moreover, as addition amount of an alumina and a silica, it is preferable to make it the value within the range of 0.1-50 weight part in total with respect to 100 weight part of titanium oxide fine particles.
This is because when the amount added is less than 0.1 parts by weight, it may be difficult to sufficiently improve the basic dispersibility of the titanium oxide fine particles. On the other hand, when the added amount exceeds 50 parts by weight, it becomes difficult to uniformly treat the titanium oxide fine particles or the influence on the conductivity of the intermediate layer becomes excessively large. This is because adjustment may be difficult.
Therefore, it is more preferable that the addition amount of the alumina and silica is a value within the range of 1 to 30 parts by weight with respect to 100 parts by weight of the titanium oxide fine particles, and a value within the range of 5 to 20 parts by weight. More preferably.

(Surface treatment with organosilicon compound)
Further, in addition to the above-mentioned alumina and silica, the titanium oxide fine particles are further subjected to a surface treatment with an organosilicon compound, and the weight ratio X (% by weight) of the organosilicon compound on the titanium oxide fine particle surface is as follows. It satisfies the relational expression (1).
1 (% by weight) ≦ X <4 (% by weight) (1)
This is because the water absorption of the titanium oxide fine particles can be controlled and the dispersibility can be further improved by performing the surface treatment with the organosilicon compound.
Furthermore, by adjusting the weight ratio of the organosilicon compound on the surface of the titanium oxide fine particles to a value within such a range, the balance between the dispersibility of the titanium oxide fine particles in the intermediate layer and the conductivity is adjusted to a good state. It is because it can do.
As a result, the balance between the pressure resistance of the photosensitive layer and the charge mobility can be improved, and as a result, the generation of black spots in a high temperature and high humidity environment can be effectively suppressed, while in a low temperature and low humidity environment. This is because excellent sensitivity characteristics can be effectively retained.
That is, when the weight ratio of the organosilicon compound is less than 1% by weight, the dispersibility of the titanium oxide fine particles in the intermediate layer may be reduced and the particles may easily aggregate. In such a case, the excessively aggregated portion becomes a path of electric charge, causing a minute leak, which is likely to cause black spots in a high temperature and high humidity environment. On the other hand, when the weight ratio of the organosilicon compound is 4% by weight or more, the conductivity of the intermediate layer is excessively lowered, and it may be difficult to release the residual charge in the photosensitive layer to the substrate side. As a result, the sensitivity characteristic in a low temperature and low humidity environment tends to be excessively lowered.
Therefore, it is more preferable to set the weight ratio X (wt%) of the organosilicon compound on the surface of the titanium oxide fine particles to a value within the range of 1 to 3.5 wt%, and within the range of 1.5 to 3 wt%. More preferably, it is a value.

Moreover, it is preferable to perform the measurement of the weight ratio X (wt%) of the organosilicon compound on the surface of the titanium oxide fine particles as follows using a fluorescent X-ray measuring apparatus.
That is, first, a calibration curve showing the correlation between the weight of the organosilicon compound and the peak intensity of the silicon atom is prepared using a fluorescent X-ray measurement apparatus.
Next, using a fluorescent X-ray measurement apparatus, the peak intensity P1 of silicon atoms on the surface of the titanium oxide fine particles before the surface treatment with the organosilicon compound and the surface of the titanium oxide fine particles after the surface treatment with the organosilicon compound are performed. The peak intensity P2 of silicon atoms is measured.
Next, the peak intensity Pm = P2-P1 of silicon atoms derived from the organosilicon compound is calculated.
Next, using a calibration curve prepared in advance, the weight (M) of the organosilicon compound on the surface of the titanium oxide fine particles after the surface treatment is calculated.
Finally, the ratio (M / T = X) (% by weight) of the weight (M) of the organosilicon compound on the surface of the titanium oxide fine particles to the weight (T) of the titanium oxide fine particles before the surface treatment with the organosilicon compound is performed. It is preferable.

Next, using FIG. 2, the weight ratio of the organosilicon compound on the surface of the titanium oxide fine particles and the single layer type electrophotographic photosensitive member containing the titanium oxide fine particles in the intermediate layer were measured in a low temperature and low humidity environment. The relationship between the sensitivity characteristics and the occurrence of black spots when an image is formed in a high temperature and high humidity environment will be described.
That is, in FIG. 2, the horizontal axis represents the weight ratio X (% by weight) of methyl hydrogen polysiloxane (a kind of organosilicon compound) on the surface of the titanium oxide fine particles, and the left vertical axis represents the light in a low temperature and low humidity environment. A characteristic curve A taking the potential difference (V) is shown.
In addition, the right vertical axis shows a characteristic curve B that takes the number of black spots (pieces / sheet) in a high temperature and high humidity environment.
Note that the light potential difference is a value obtained by subtracting the value of the light potential when the intermediate layer is not provided from the value of the light potential when the intermediate layer is provided.
The titanium oxide fine particles used had a number average primary particle size of all 10 nm and were subjected to the same surface treatment with alumina and silica before the surface treatment with methylhydrogenpolysiloxane.
Further, the titanium oxide fine particles were contained in an amount of 300 parts by weight with respect to 100 parts by weight of the binder resin of the intermediate layer.
Other details such as the measurement conditions of the bright potential and the number of black spots are described in the examples.

First, from the characteristic curve A, the light potential difference in the low temperature and low humidity environment decreases once and then increases as the weight ratio X of methylhydrogenpolysiloxane (hereinafter simply referred to as X) increases. Is understood.
More specifically, as the value of X increases from 0% by weight to 1% by weight, the value of the bright potential difference suddenly decreases from a value of just over 60V to a value of over 20V, and the sensitivity characteristic is remarkable. It can be seen that there is an improvement. On the other hand, in the range where the value of X exceeds 1% by weight, the value of the bright potential continues to increase relatively gradually as the value of X increases, but in the range where the value of X is less than 4% by weight. If it exists, it turns out that the value of a bright potential difference can be hold | maintained in the practically acceptable range of about 40V.

Next, it can be understood from the characteristic curve B that the number of black spots generated under a high temperature and high humidity environment decreases as X increases.
More specifically, as the value of X increases from 0% by weight to 1% by weight, the number of sunspots sharply decreases from 90 / sheet to just over 40 / sheet, and thereafter It can be seen that it continues to decrease moderately.
Therefore, it can be seen that when the value of X is in the range of 1% by weight or more, the number of black spots generated can be maintained within a practically acceptable range of 40 or less.

  From the above, judging from the characteristic curves A and B in combination, by maintaining the value of X within the range of 1 wt% or more and less than 4 wt%, it is possible to maintain an excellent light potential in a low temperature and low humidity environment, It can also be seen that the overall contradictory purpose of suppressing the occurrence of black spots in a high temperature and high humidity environment can be effectively realized.

Moreover, it is preferable that the surface treatment by the organosilicon compound is performed on the surface treatment layer by alumina and silica.
The reason for this is that by doing so, more uniform and more favorable conductivity can be imparted to the intermediate layer.
That is, by doing in this way, the effect obtained by defining the weight ratio of the organosilicon compound on the surface of the titanium oxide fine particles as shown in FIG. This is because it can.

The organosilicon compound preferably used in the present invention is an alkylsilane compound, an alkoxysilane compound, a vinyl group-containing silane compound, a mercapto group-containing silane compound, an amino group-containing silane compound, or a condensation polymer thereof. Examples include polysiloxane compounds.
More specifically, siloxane compounds such as methyl hydrogen polysiloxane and dimethyl polysiloxane are preferable, and methyl hydrogen polysiloxane is particularly preferable.

Further, the addition amount of the organosilicon compound may be a value within the range of 1 part by weight or more and less than 4 parts by weight with respect to 100 parts by weight of the titanium oxide fine particles surface-treated with alumina and silica. preferable.
The reason for this is that when the treatment amount of the organosilicon compound is less than 1 part by weight, it is difficult to obtain the treatment effect of the organosilicon compound and the dispersibility may not be improved. On the other hand, when the treatment amount of the organosilicon compound becomes a value of 4 parts by weight or more, the coating amount by the organosilicon compound becomes excessively large, and it may be difficult to effectively exhibit the electrical characteristics of titanium oxide. Because.
Therefore, it is more preferable to set the addition amount of the organosilicon compound to a value within the range of 1.2 to 3.5 parts by weight with respect to 100 parts by weight of the titanium oxide fine particles surface-treated with alumina and silica. More preferably, the value is in the range of 5 to 3 parts by weight.

(1) -3 Content The content of the titanium oxide fine particles is preferably set to a value within the range of 120 to 450 parts by weight with respect to 100 parts by weight of the binder resin of the intermediate layer.
This is because by setting the content of the titanium oxide fine particles in such a range, it is possible to impart more uniform and more preferable conductivity to the intermediate layer.
That is, when the content is less than 120 parts by weight with respect to 100 parts by weight of the binder resin of the intermediate layer, the conductivity of the intermediate layer becomes excessively small, and residual charges in the photosensitive layer are released to the substrate side. This may be difficult. On the other hand, when the content exceeds 450 parts by weight with respect to 100 parts by weight of the binder resin in the intermediate layer, the conductivity of the intermediate layer becomes excessively large, or the titanium oxide fine particles aggregate in the intermediate layer. This is because black spots are likely to occur.
Therefore, the content of the titanium oxide fine particles is more preferably set to a value in the range of 130 to 400 parts by weight with respect to 100 parts by weight of the binder resin of the intermediate layer, and a value in the range of 150 to 350 parts by weight. More preferably.
The addition amount of the titanium oxide fine particles means the addition amount of the titanium oxide fine particles after the surface treatment.
In addition, when the titanium oxide fine particles according to the present invention and the other titanium oxide and fine particles are used in combination, the total amount thereof is meant.

(2) Additive In addition, in the intermediate layer, various additives (organic fine powders) different from the charge transporting pigment are used for the purpose of preventing the occurrence of interference fringes by causing light scattering and improving the dispersibility. It is preferable to add an inorganic fine powder).
Particularly preferred additives are white pigments such as zinc oxide, zinc sulfide, lead white and lithopone, inorganic pigments such as alumina, calcium carbonate and barium sulfate, fluororesin particles, benzoguanamine resin particles and styrene resin particles. It is.
Moreover, when adding additives, such as a fine powder, it is preferable to make the particle diameter into the value within the range of 0.01-3 micrometers. The reason for this is that if the particle size is too large, the unevenness of the intermediate layer may increase, an electrically non-uniform portion may occur, and image quality defects may easily occur. On the other hand, if the particle size is too small, a sufficient light scattering effect may not be obtained.
In addition, when adding additives, such as a fine powder, the addition amount shall be the value within the range of 1-70 weight% by weight ratio with respect to solid content of an intermediate | middle layer, More preferably, it is 5-60 weight%. It is preferable.

(3) Binder Resin (3) -1 Types The types of binder resin include, for example, polyamide resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyvinyl formal resin, vinyl acetate resin, phenoxy resin, polyester resin, and acrylic resin. It is preferable to use at least one resin selected from the group consisting of:
Among these, it is particularly preferable to use a polyamide resin.
This is because the polyamide resin can effectively improve the adhesion between the substrate and the photosensitive layer while improving the dispersibility of the titanium oxide fine particles in the intermediate layer.

Here, when a polyamide resin is used, it is preferable to use an alcohol-soluble polyamide resin because it is excellent in solubility in a solvent. Specific examples include what is called a copolymer nylon obtained by copolymerizing nylon 6, nylon 66, nylon 610, nylon 11, nylon 12, and the like, N-alkoxymethyl-modified nylon, N-alkoxyethyl nylon, and the like. It is preferable to use what is called modified nylon obtained by chemically modifying nylon.
Moreover, when using polyvinyl butyral resin and polyvinyl formal resin, what contains 50-75 mol% of vinyl acetal, 10-50 mol% of polyvinyl alcohol, and polyvinyl acetate 0-15 mol% in the structure is used. It is preferable.
The polyvinyl butyral resin is obtained by reacting butyraldehyde with a polyvinyl alcohol resin, and the polyvinyl formal resin can be obtained by reacting formaldehyde with a polyvinyl alcohol resin. It is a preferable resin because it is excellent in compatibility with a resin and has excellent reactivity and adhesion with a phenol resin.

(3) -2 Number average molecular weight Moreover, it is preferable to make the number average molecular weight of binder resin into the value within the range of 1,000-60,000.
The reason for this is that when the average molecular weight of the binder resin is less than 1,000, the viscosity of the coating liquid when forming the intermediate layer is remarkably lowered, making it difficult to obtain a uniform film thickness or mechanical strength. This is because the film formability or the adhesiveness may be significantly lowered. On the other hand, if the average molecular weight of the binder resin exceeds 60,000, the viscosity of the coating solution when forming the intermediate layer is remarkably increased, making it difficult to control the thickness of the intermediate layer, or charge mobility. This is because there is a case in which the remarkably decreases.
Accordingly, the average molecular weight of the binder resin is more preferably set to a value within the range of 2,000 to 40,000, and further preferably set to a value within the range of 5,000 to 20,000.
The average molecular weight of the binder resin can also be measured as a molecular weight in terms of polystyrene using gel permeation chromatography (GPC), or when the binder resin is a condensation resin, its degree of condensation. It can also be calculated by calculation.

(4) Film thickness Moreover, it is preferable to make the film thickness of an intermediate | middle layer into the value within the range of 0.1-50 micrometers.
This is because the conductivity of the intermediate layer can be made more uniform and more suitable by setting the film thickness of the intermediate layer in such a range.
That is, if the thickness of the intermediate layer is less than 0.1 μm, it may be difficult to sufficiently improve the pressure resistance of the photosensitive layer. On the other hand, if the thickness of the intermediate layer exceeds 50 μm, the charge mobility in the photosensitive layer may be excessively lowered.
Therefore, the thickness of the intermediate layer is more preferably set to a value within the range of 0.5 to 40 μm, and further preferably set to a value within the range of 1 to 30 μm.

4). Photosensitive layer (1) Charge generator (1) -1 type Examples of the charge generator include phthalocyanine pigments such as metal-free phthalocyanine and titanyl phthalocyanine, perylene pigments, bisazo pigments, metal-free naphthalocyanine pigments, and metals. Organic light such as naphthalocyanine pigment, squaraine pigment, trisazo pigment, indigo pigment, azurenium pigment, cyanine pigment, pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment, quinacridone pigment Conventionally known charge generating agents such as conductors, inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon can be used.
More specifically, it is more preferable to use phthalocyanine pigments (CGM-A to CGM-D) represented by the following formulas (1) to (4).
This is because a photoreceptor having sensitivity in a wavelength region of 600 to 800 nm or more is required when used in a digital optical image forming apparatus such as a laser beam printer or a facsimile provided with a semiconductor laser as a light source. It is.
When used in an analog optical image forming apparatus such as an electrostatic copying machine equipped with a white light source such as a halogen lamp, a photosensitive member having sensitivity in the visible region is required. A pigment, a bisazo pigment, or the like can be preferably used.

Among the phthalocyanine pigments described above, it is particularly preferable to use a titanyl phthalocyanine crystal having the following characteristics (A) and (B).
(A) In a CuKα characteristic X-ray diffraction spectrum, it has a main peak at a Bragg angle of 2θ ± 0.2 ° = 27.2 °.
(B) In differential search calorimetric analysis, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
The reason for this is that by using a titanyl phthalocyanine crystal having such predetermined characteristics, excellent sensitivity characteristics can be more effectively maintained even in a low temperature and low humidity environment.
That is, because the titanyl phthalocyanine crystal has the characteristic (A), its crystal stability, charge generation ability and dispersibility can be remarkably improved.
Further, the titanyl phthalocyanine crystal has the characteristic (B), so that its crystal stability, charge generation ability and dispersibility can be further improved.
In addition, it is more preferable that one peak appearing in the range of 270 to 400 ° C. other than the peak accompanying vaporization of the adsorbed water appears in the range of 290 to 400 ° C., and the range of 300 to 400 ° C. More preferably, it appears within.

In order to obtain a titanyl phthalocyanine crystal having the characteristics (A) and (B) described above, the amount of titanium alkoxide such as titanium tetrabutoxide or titanium tetrachloride added as a material substance when synthesizing a titanyl phthalocyanine compound To a value within the range of 0.40 to 0.53 moles per mole of o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or a derivative thereof as another material substance Is preferable, and a value within the range of 0.42 to 0.50 mol is more preferable.
Further, it is preferable to synthesize the titanyl phthalocyanine compound in the presence of the urea compound. In this case, the amount of the urea compound added is o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or It is preferable to set it as the value within the range of 0.1-0.95 mol with respect to 1 mol of the derivatives, and it is more preferable to set it as the value within the range of 0.2-0.8 mol.

Next, the relationship between the type of charge generating agent and the sensitivity characteristics in a low temperature and low humidity environment will be described with reference to FIG.
That is, in FIG. 3, the horizontal axis represents the weight ratio X (% by weight) of methyl hydrogen polysiloxane (a kind of organosilicon compound) on the surface of the titanium oxide fine particles, and the vertical axis represents the light potential in a low temperature and low humidity environment. Characteristic curves A and B taking (V) are shown.
Here, the characteristic curve A is a characteristic curve when the titanyl phthalocyanine crystal having the characteristics (A) and (B) described above is used as the charge generating agent, and the characteristic curve B is a characteristic curve of metal-free phthalocyanine as the charge generating agent. It is a characteristic curve at the time of using an x-type crystal.
The titanium oxide fine particles used at this time all had a number average primary particle diameter of 10 nm, and those subjected to the same surface treatment with alumina and silica before the surface treatment with methylhydrogenpolysiloxane were used. .
Further, 300 parts by weight of the titanium oxide fine particles were contained with respect to 100 parts by weight of the binder resin of the intermediate layer, and 3 parts by weight of the charge generator was contained with respect to 100 parts by weight of the binder resin of the photosensitive layer.
In addition, details such as measurement conditions of the bright potential are described in the examples.

First, it is understood from the characteristic curves A and B that the value of the bright potential once decreases and increases as the value of X increases regardless of the type of the charge generating agent. .
And, in the range where the value of X is 1% by weight or more and less than 4% by weight, the value of the light potential can be set to a low value (the lower the value of the light potential, the better the sensitivity characteristic is). I understand.
However, in the characteristic curves A and B, the level of the overall light potential value is different.
More specifically, in the characteristic curve A, when the value of X is 0% by weight, that is, when the titanium oxide fine particles are not subjected to surface treatment with an organosilicon compound, the value of the bright potential is It is a little over 130V.
On the other hand, in the characteristic curve B, even if the value of X is 3.5% by weight and the value of the light potential is the lowest, the value of the light potential is less than 135V.
Therefore, from the characteristic curves A and B, by using the titanyl phthalocyanine crystal having the characteristics (A) and (B) as the charge generating agent, the sensitivity characteristics of the electrophotographic photosensitive member can be effectively obtained even in a low temperature and low humidity environment. It can be seen that the bottom can be raised.
In addition, between the case where the titanyl phthalocyanine crystal having the characteristics (A) and (B) is used and the case where the general titanyl phthalocyanine crystal not having these characteristics is used, the temperature is low. It has been confirmed that significant differences occur in the sensitivity characteristics (see Examples).

(1) -2 Content The content of the charge generating agent is preferably set to a value in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the binder resin described later.
This is because the charge generator can efficiently generate charges when the photosensitive layer surface is exposed by setting the content of the charge generator within such a range. .
That is, when the content of the charge generating agent is less than 0.1 part by weight with respect to 100 parts by weight of the binder resin, the amount of charge generated is insufficient to form an electrostatic latent image on the surface of the photosensitive layer. This is because there is a case of becoming. On the other hand, if the content of the charge generating agent exceeds 50 parts by weight with respect to 100 parts by weight of the binder resin, it may be difficult to uniformly disperse in the coating solution for the photosensitive layer. It is.
Therefore, the content of the charge generating agent with respect to 100 parts by weight of the binder resin is more preferably set to a value within the range of 0.2 to 40 parts by weight, and a value within the range of 0.5 to 30 parts by weight. Is more preferable.

(2) Charge transport agent (2) -1 type As the charge transport agent (hole transport agent and electron transport agent) used in the charge transport layer, 2,5-bis (p-diethylaminophenyl) -1,3 Oxadiazole derivatives such as 1,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) ) Aromatic tertiary amino such as pyrazoline derivatives such as pyrazoline, triphenylamine, tri (p-methyl) phenylamine, N, N-bis (3,4-dimethylphenyl) biphenyl-4-amine, dibenzylaniline Aromatic tertiary diamino compounds such as compounds, N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1-biphenyl] -4,4'-diamine 1,2,4-triazine derivatives such as 3- (4′-dimethylaminophenyl) -5,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde-1 , Hydrazone derivatives such as 1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) -benzofuran, p- (2 , 2-diphenylvinyl) -N, N-diphenylaniline and other α-stilbene derivatives, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, hole transport materials such as poly-N-vinylcarbazole and derivatives thereof; chloranil, Quinone compounds such as bromoanil and anthraquinone, tetracyanoquinodimethane , Fluorenone compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, xanthone compounds, thiophene compounds, diphenoquinone compounds and other electron transport materials; One kind or a combination of two or more kinds of polymers having a group to be formed in the main chain or side chain can be mentioned.

(2) -2 Content The content of the hole transport agent is preferably set to a value in the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin of the photosensitive layer. A value within the range of parts by weight is preferred.
Further, the content of the electron transport agent is preferably a value within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin of the photosensitive layer, and a value within the range of 20 to 70. Is more preferable.

(3) Additives In addition, for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, light, or heat generated in the electrophotographic apparatus, an antioxidant, a light stabilizer, and heat stability in the photoreceptor layer. It is preferable to add an agent or the like.
For example, as the antioxidant, hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, and the like are used. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine.

(4) Binder resin The type of the binder resin is not particularly limited. For example, a polycarbonate resin, a polyester resin, a polyarylate resin, a styrene-butadiene copolymer, and a styrene-acrylonitrile copolymer are used. , Styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer Polymers, alkyd resins, polyamides, polyurethanes, polysulfones, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyether resins, and other thermoplastic resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other crosslinks Heat hardening Resins such as photocurable resins such as curable resins, epoxy acrylates and urethane acrylates can be used.

(5) Film thickness Moreover, it is preferable to make the film thickness of a photosensitive layer into the value within the range of 5.0-100 micrometers.
This is because when the thickness of the photosensitive layer is less than 5.0 μm, the mechanical strength of the photosensitive member may be insufficient. On the other hand, when the thickness of the photosensitive layer exceeds 100 μm, it may be easy to peel off from the intermediate layer or it may be difficult to form it uniformly. Accordingly, the thickness of the photosensitive layer is more preferably set to a value within the range of 10 to 80 μm, and further preferably set to a value within the range of 20 to 40 μm.

5). Manufacturing Method (1) Preparation of Substrate In order to prevent the occurrence of interference fringes, the surface of the supporting substrate is formed using methods such as etching, anodizing, wet blasting, sand blasting, rough cutting, and centerless cutting. It is preferable to perform a roughening treatment.

(2) Formation of Intermediate Layer (2) -1 Surface Treatment of Titanium Oxide Fine Particles As a method for subjecting titanium oxide fine particles to surface treatment, for example, using a pulverizer without using a solvent, organosilicon It is preferable to use a dry treatment method in which a compound and titanium oxide fine particles in which alumina and silica are precipitated are mixed and dispersed to treat the surface of the titanium oxide fine particles.
In addition, an organosilicon compound dissolved in an appropriate solvent is added to a slurry of titanium oxide having alumina and silica deposited on the surface, and then stirred and then dried to wet the surface treatment of titanium oxide. It is also preferable to use a processing method.
In addition, since a more uniform surface treatment is possible with a dry processing method and a wet processing method, a wet processing method is more preferable.

Moreover, as a wet processing method, it is preferable to use a wet media dispersion type apparatus.
This is because such a wet media dispersion type device is excellent in dispersibility, so that uniform surface treatment can be performed while effectively crushing and dispersing the aggregated particles of titanium oxide.
Here, the wet media dispersion type device is a device in which a medium is filled in the device and includes a member for improving the dispersion force, such as a stirring disk capable of rotating at high speed.
Moreover, it is preferable to use a ball | bowl, a bead, etc. as a medium mentioned above, and in order to perform a more uniform surface treatment, it is preferable to use a bead.
As the raw material for the beads, alumina, glass, zircon, zirconia, steel, front stone and the like are preferably used.
The bead diameter is preferably in the range of 0.3 to 2 mm.

(2) -2 Preparation of coating solution for intermediate layer Further, in forming the intermediate layer, the above-described titanium oxide fine particles are added to a solution in which the resin component is dissolved, and dispersion treatment is performed to form a coating solution. Is preferred.
The method for performing the dispersion treatment is not particularly limited, but generally known roll mills, ball mills, vibration ball mills, attritors, sand mills, colloid mills, paint shakers and the like are preferably used.

(2) -3 Application of Intermediate Layer Coating Solution Further, the application method of the intermediate layer application solution is not particularly limited, but dip coating method, spray coating method, bead coating method, blade coating method, roller A coating method such as a coating method can be used.
In order to form the intermediate layer and the photosensitive layer thereon more stably, it is possible to carry out a heat drying treatment at 30 to 200 ° C. for 5 minutes to 2 hours after application of the intermediate layer coating solution. preferable.

(3) Formation of photosensitive layer Further, as a method for forming a photosensitive layer, after preparing a photosensitive layer coating solution, a coating method such as a dip coating method, a spray coating method, a bead coating method, a blade coating method, a roller coating method, etc. It is preferable to form a photoreceptor layer using and to heat and dry. Moreover, it is preferable that the conditions of heat drying shall be the range of 5 minutes-2 hours at the temperature of 30-200 degreeC, for example.

[Second Embodiment]
The second embodiment of the present invention includes the single-layer type electrophotographic photosensitive member as the first embodiment, and a charging unit, a developing unit, a transfer unit, and a cleaning unit around the single-layer type electrophotographic photosensitive member. An image forming apparatus in which a unit and a charge eliminating unit are arranged.
Hereinafter, the contents already described in the first embodiment will be omitted, and the second embodiment will be described focusing on differences from the first embodiment.

The basic configuration and operation of the image forming apparatus of the present invention will be described with reference to FIG.
First, the single-layer electrophotographic photosensitive member 10 of the image forming apparatus 100 is rotated in a direction indicated by an arrow A at a predetermined process speed (peripheral speed), and then the surface is charged with a predetermined potential (plus polarity) by the charging unit 112. To charge. In FIG. 4, a charging roll is used as the charging unit 112.
Next, the exposure unit 113 exposes the surface of the single-layer electrophotographic photosensitive member 10 through a reflection mirror or the like while being optically modulated according to image information. By this exposure, an electrostatic latent image is formed on the surface of the single-layer electrophotographic photoreceptor 10.
Next, based on the electrostatic latent image, latent image development is performed by the developing unit 114. The developing means 114 contains toner, and the toner adheres corresponding to the electrostatic latent image on the surface of the single-layer electrophotographic photosensitive member 10 to form a toner image.
The recording paper 120 is conveyed to the lower part of the single-layer electrophotographic photosensitive member 10 along a predetermined transfer conveyance path. At this time, a toner image can be transferred onto the recording material 120 by applying a predetermined transfer bias between the single-layer electrophotographic photosensitive member 10 and the transfer means 115.

Next, the recording paper 120 on which the toner image has been transferred is separated from the surface of the single-layer electrophotographic photosensitive member 10 by a separating means (not shown) and conveyed to a fixing device by a conveying belt. Next, the toner image is fixed on the surface by being heated and pressed by the fixing device, and then discharged to the outside of the image forming apparatus 100 by a discharge roller.
On the other hand, the single-layer electrophotographic photosensitive member 10 after the toner image transfer continues to rotate, and residual toner (adhered matter) that has not been transferred to the recording paper 120 at the time of transfer is transferred from the surface of the single-layer electrophotographic photosensitive member 10. It is removed by the cleaning device 117. Further, the charge remaining on the surface of the single-layer electrophotographic photosensitive member 10 is erased by the charge eliminating means 102 and used for the next image formation.

In the image forming apparatus of the present invention, as described in the first embodiment, a single layer type electrophotographic photoreceptor containing a specific titanium oxide is used in the intermediate layer.
Therefore, the generation of black spots in a high temperature and high humidity environment can be effectively suppressed, while excellent sensitivity characteristics can be effectively maintained even in a low temperature and low humidity environment.

In configuring the image forming apparatus of the present invention, it is preferable that the charging unit is a contact type charging unit.
The reason for this is that charging can be stably performed without being affected by temperature and humidity as compared with a non-contact type charging means.
That is, in the non-contact type charging means, since the photosensitive member is charged through air by discharging, charging may become unstable due to the influence of the temperature and humidity of the air. On the other hand, a contact-type charging means does not cause such a problem and can stably charge the photosensitive member. Furthermore, if it is a contact charging type charging means, the overall structure is simpler than non-contact type charging means, and since there is little generation of oxidizing gas such as ozone, it is excellent in environmental characteristics. I can say that.

Further, the charging means is preferably a charging means for charging the surface of the single-layer electrophotographic photosensitive member to a positive polarity.
This is because the positive polarity type charging means can suppress the oxidative deterioration of the photosensitive layer due to an oxidizing gas such as ozone as compared with the negative polarity type, so that the pressure resistance of the photosensitive layer is stable. This is because generation of black spots can be more effectively suppressed even in a high temperature and high humidity environment.

The cleaning means is preferably a cleaning means that employs a roller cleaning system that polishes the surface of the single-layer electrophotographic photosensitive member with a roller member.
The reason for this is that with such a cleaning means, the portion of the photosensitive layer surface that has been oxidized and deteriorated or the portion of the residual toner that has undergone filming is polished and removed to effectively maintain the pressure resistance of the photosensitive layer. It is because it can do.
On the other hand, as the polishing of the photosensitive layer progresses, the pressure resistance of the photosensitive layer may tend to decrease. However, according to the present invention, the single-layer electrophotographic photosensitive member has a predetermined intermediate layer. This is because such a problem can be solved, and the generation of black spots can be effectively suppressed even in a high temperature and high humidity environment.

The peripheral speed (process speed) of the single layer type electrophotographic photosensitive member is preferably set to a value of 100 mm / sec or more.
The reason for this is that by setting the peripheral speed of the single-layer type electrophotographic photosensitive member in such a range, oxidation deterioration on the surface of the photosensitive layer and filming due to residual toner are likely to occur, and the pressure resistance of the photosensitive layer is increased. In the present invention, since the single-layer electrophotographic photosensitive member has a predetermined intermediate layer, the generation of black spots is effective even in a high temperature and high humidity environment. This is because it can be suppressed.
Moreover, even in a low-temperature and low-humidity environment, it is possible to exhibit excellent sensitivity characteristics that can cope with such high speeds.
From the viewpoint of performing more stable image formation, the peripheral speed of the single-layer electrophotographic photosensitive member is more preferably set to a value within the range of 100 to 400 mm / sec, and within the range of 100 to 300 mm / sec. More preferably, it is a value.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these description content.

[Example 1]
1. Surface treatment of titanium oxide fine particles In a container, 100 parts by weight of titanium oxide fine particles (manufactured by Teika Co., Ltd., MT-05, number average primary particle size: 10 nm) surface-treated with silica and alumina, methyl hydrogen polysiloxane (MHPS) ) 1 part by weight and 100 parts by weight of toluene were added and mixed to obtain a cloudy liquid. Next, this cloudy solution was stirred for 20 minutes using a stirrer to obtain a slurry of fine titanium oxide particles. Next, after kneading the slurry of titanium oxide fine particles obtained using a kneader, the solvent was removed by heating under reduced pressure to obtain surface-treated titanium oxide fine particles (before heat treatment). Next, the obtained titanium oxide fine particles (before heat treatment) were cured (heat treatment) at 150 ° C. to obtain surface-treated titanium oxide fine particles.
The number average primary particle diameter of the titanium oxide fine particles after the surface treatment was 10 nm.

2. Measurement of weight ratio of organosilicon compound Further, the weight ratio of methylhydrogenpolysiloxane on the surface of the obtained surface-treated titanium oxide particles was measured.
That is, first, a calibration curve showing a correlation between the weight of methyl hydrogen polysiloxane and the peak intensity of silicon atoms was prepared using a fluorescent X-ray measurement apparatus.
Next, using a fluorescent X-ray measurement apparatus, the peak intensity P1 of silicon atoms on the surface of the titanium oxide fine particles before the surface treatment with methyl hydrogen polysiloxane and the oxidation after the surface treatment with methyl hydrogen polysiloxane are performed. The peak intensity P2 of silicon atoms on the surface of the titanium fine particles was measured.
Subsequently, the peak intensity Pm = P2-P1 of the silicon atom derived from methyl hydrogen polysiloxane was calculated.
Subsequently, the weight (M) of methyl hydrogen polysiloxane on the surface of the titanium oxide fine particles after the surface treatment was calculated using a calibration curve prepared in advance.
Finally, the ratio (M / T = X) of the weight (M) of methyl hydrogen polysiloxane on the surface of the titanium oxide fine particles to the weight (T) of the titanium oxide fine particles before the surface treatment with methyl hydrogen polysiloxane. %). The obtained results are shown in Table 1.
The weight (T) of the titanium oxide fine particles before the surface treatment with methyl hydrogen polysiloxane is the weight of the titanium oxide fine particles after the surface treatment with alumina and silica.

Moreover, the measurement by the fluorescent X-ray measuring apparatus was performed as follows.
That is, a predetermined amount of titanium oxide fine particles before surface treatment with an organosilicon compound was applied with a pressure of 20 MPa for 3 seconds using a sample press molding machine (BRE-32: manufactured by MAEKAWA TESTING MACHINE) to form a circular shape. After that, the fluorescent X-ray peak intensity (kcps) attributed to Si was measured using a fluorescent X-ray measuring apparatus RIX200 manufactured by Rigaku Corporation (voltage: 50 kV, current: 30 mA, X-ray tube: Rh).
Similarly, the fluorescence attributed to Si is similarly applied to the titanium oxide fine particles after the surface treatment with the organosilicon compound to the predetermined amount of the titanium oxide fine particles before the surface treatment with the organosilicon compound. X-ray peak intensity was measured.

3. Formation of Intermediate Layer Using a ball mill, 300 parts by weight of the obtained titanium oxide fine particles, 100 parts by weight of copolymer nylon (manufactured by Daicel Degussa Co., Ltd., X1010), 800 parts by weight of ethanol, and 300 parts by weight of butanol are mixed for 48 hours. -Dispersed to obtain an intermediate layer coating solution.
Next, the obtained intermediate layer coating solution was filtered through a 5 μm filter, and then one end of an aluminum base tube having a diameter of 30 mm and a length of 254 mm was turned up, and the obtained intermediate layer coating solution was 5 mm / sec. It was immersed and applied at a speed of (dip coating method). Subsequently, it heat-processed on 130 degreeC and the conditions for 30 minutes, and formed the intermediate | middle layer with a film thickness of 3 micrometers.

4). Formation of Photosensitive Layer Next, using a ball mill, 3 parts by weight of a metal-free phthalocyanine (CGM-A) x-type crystal (xH ₂ Pc) represented by the formula (1) as a charge generating agent, and a hole transporting agent 50 parts by weight of a compound (HTM-1) represented by the following formula (5), 30 parts by weight of a compound (ETM-1) represented by the following formula (6) as an electron transporting agent, Z type represented by the following formula (7) 100 parts by weight of polycarbonate resin (TS2020, manufactured by Teijin Chemicals Ltd.) and 800 parts of tetrahydrofuran were mixed and dispersed for 50 hours to obtain a coating solution for the photosensitive layer.
Subsequently, the obtained photosensitive layer coating solution was applied on the already formed intermediate layer by a dip coating method.
Subsequently, it heat-processed on 130 degreeC and the conditions for 30 minutes, the 30-micrometer-thick photosensitive layer was formed, and the single layer type electrophotographic photoreceptor was obtained.

5). Evaluation (1) Evaluation of light potential The light potential of the obtained single-layer electrophotographic photosensitive member was evaluated.
That is, the obtained single-layer type electrophotographic photosensitive member is mounted on a printer (manufactured by Kyocera Mita Co., Ltd., FS-1010 modified machine) under low temperature and low humidity conditions (temperature: 10 ° C., relative humidity: 20%). The surface potential was set to 400 V and exposure corresponding to a solid image was performed.
Next, the surface potential at the exposure position was measured to obtain bright electrons. The obtained results are shown in Table 1.

In addition, a single layer type electrophotographic photosensitive member produced in the same manner as the single layer type electrophotographic photosensitive member described above was prepared except that no intermediate layer was provided, and the light potential (V) was measured in the same manner.
Further, a value obtained by subtracting the value of the light potential when the intermediate layer is not provided from the value of the light potential when the intermediate layer is provided, that is, a light potential difference (V) is calculated and evaluated according to the following criteria: did. The obtained results are shown in Table 1.
A: The value of the light potential difference is less than 20V.
A: The value of the bright potential difference is a value less than 20 to 50V.
X: The value of the bright potential difference is a value of 50 V or more.

(2) Evaluation of black spots Next, black spots were evaluated when an image was formed using the obtained single layer type electrophotographic photosensitive member.
That is, the obtained single-layer type electrophotographic photosensitive member is mounted on a printer (manufactured by Kyocera Mita Co., Ltd., FS-1010 modified machine), and in a high temperature and high humidity environment (temperature: 35 ° C., relative humidity: 85%). In FIG. 5, after continuous durable printing of 5,000 blank paper images, the paper was left for one day.
Subsequently, ten blank paper images were printed, and the number of black spots (number / sheet) in the tenth image was visually counted and evaluated according to the following criteria. The obtained results are shown in Table 1.
A: The number of black spots generated is less than 30 / sheet.
○: The number of black spots generated is 30 to less than 80 / sheet.
X: The number of black spots generated is 80 or more.

(3) Comprehensive evaluation Moreover, in order to evaluate each evaluation result mentioned above comprehensively, comprehensive evaluation was performed according to the following reference | standard.
A: Both the evaluation of the bright potential difference and the evaluation of the number of black spots generated are A.
◯: Both the evaluation of the bright potential difference and the evaluation of the number of black spots generated are not ◎, but are ○ or ◎.
X: The evaluation of the bright potential difference or the evaluation of the number of black spots generated is x.

[Example 2]
In Example 2, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the amount of methyl hydrogen polysiloxane added was changed to 2 parts by weight when the surface treatment was performed on the titanium oxide fine particles. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 3]
In Example 3, a single-layer electrophotographic photosensitive member was used in the same manner as in Example 1 except that the amount of methylhydrogenpolysiloxane added was changed to 3.5 parts by weight when the surface treatment was performed on the titanium oxide fine particles. The body was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 4]
In Example 4, when the photosensitive layer is formed, the charge generating agent is a Y-type crystal of titanyl phthalocyanine (CGM-B) represented by the formula (2), which has the characteristic (A). B) is a single layer type electrophotographic photosensitive member in the same manner as in Example 1 except that a crystal having no B, that is, a conventional Y-type crystal (Y-TiOPc-1) conventionally used is used. And evaluated. The obtained results are shown in Table 1.

[Example 5]
In Example 5, a single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the amount of methyl hydrogen polysiloxane added was changed to 3.5 parts by weight when the surface treatment was performed on the titanium oxide fine particles. The body was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 6]
Example 6 is a Y-type crystal of titanyl phthalocyanine (CGM-B) represented by the formula (2) as a charge generator when forming the photosensitive layer, and has characteristics (A) and (B). A single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that crystal (Y-TiOPc-2) was used. The obtained results are shown in Table 1.
Such Y-TiOPc-2 was produced as follows.

1. Synthesis of crude titanyl phthalocyanine crystal First, in an argon-substituted flask, 22 g (0.17 mol) of o-phthalonitrile, 25 g (0.073 mol) of titanium tetrabutoxide, 300 g of quinoline, and 2.28 g (0.038 mol) of urea. ) And the temperature was raised to 150 ° C. with stirring.
Next, the temperature of the system was raised to 215 ° C. while distilling off the vapor generated from the reaction system, and the mixture was further stirred for 2 hours while maintaining this temperature.
Then, after the reaction is completed, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out of the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. Then, 24 g of a blue-violet solid as a crude titanyl phthalocyanine crystal was synthesized.

2. Pre-acid treatment step 10 g of the blue-purple solid obtained in the production of the above-mentioned titanyl phthalocyanine compound is added to 100 ml of N, N-dimethylformamide, heated to 130 ° C. with stirring, and stirred for 2 hours. It was.
Next, the heating was stopped when 2 hours passed, and further the stirring was stopped when the temperature was cooled to 23 ± 1 ° C. In this state, the liquid was allowed to stand for 12 hours for stabilization treatment. The stabilized supernatant was filtered off with a glass filter, and the resulting solid was washed with methanol and then vacuum dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound.

3. Acid treatment step 5 g of the crude crystal of titanyl phthalocyanine obtained in the above-described pre-acid treatment step was added to 100 ml of concentrated sulfuric acid and dissolved.
Next, this solution was added dropwise to ice-cooled water, stirred for 15 minutes at room temperature, and then allowed to stand at about 23 ± 1 ° C. for 30 minutes for recrystallization.
Next, the liquid described above was filtered off with a glass filter, and the obtained solid was washed with water until the washing liquid became neutral, and then dispersed in 200 ml of chlorobenzene in the presence of water without drying. The mixture was heated to 0 ° C. and stirred for 10 hours.
Next, after the liquid was filtered off with a glass filter, the obtained solid was vacuum dried at 50 ° C. for 5 hours to obtain 4.1 g of unsubstituted titanyl phthalocyanine crystals (blue powder) represented by the formula (2). Got.

4). Evaluation of titanyl phthalocyanine crystal (X-ray diffraction measurement)
0.3 g of the obtained titanyl phthalocyanine crystal was dispersed in 5 g of tetrahydrofuran, stored in a closed system for 24 hours under conditions of a temperature of 23 ± 1 ° C. and a relative humidity of 50 to 60%, and then the tetrahydrofuran was removed. The measurement was performed by filling a sample holder of an X-ray diffractometer (RINT1100 manufactured by Rigaku Corporation). The obtained spectrum chart is shown in FIG. Further, since this spectrum chart has a main peak at a Bragg angle 2θ ± 0.2 ° = 27.2 °, the obtained titanyl phthalocyanine crystal is a Y-type crystal and has the characteristic (A). It was confirmed that
Note that a spectrum chart similar to that shown in FIG. 5 was also measured before the dispersion in tetrahydrofuran.
The measurement conditions for the X-ray diffraction were as follows.
X-ray tube: Cu
Tube voltage: 40 kV
Tube current: 30 mA
Start angle: 3.0 °
Stop angle: 40.0 °
Scanning speed: 10 ° / min

(Differential scanning calorimeter measurement)
Moreover, differential scanning calorimetry of the obtained titanyl phthalocyanine crystal was performed using a differential scanning calorimeter (TAS-200 type, DSC8230D manufactured by Rigaku Corporation). The obtained differential scanning analysis chart is shown in FIG. In addition, in this chart, since one peak was confirmed at 296 ° C. in addition to the peak accompanying vaporization of adsorbed water, the obtained titanyl phthalocyanine crystal also has the characteristic (B). It could be confirmed.
The measurement conditions were as follows.
Sample pan: Aluminum heating rate: 20 ° C / min

[Example 7]
In Example 7, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 6 except that the amount of methyl hydrogen polysiloxane added was changed to 2 parts by weight when the surface treatment was performed on the titanium oxide fine particles. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 8]
In Example 8, a single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 6 except that the amount of methyl hydrogen polysiloxane added was changed to 3.5 parts by weight when the surface treatment was performed on the titanium oxide fine particles. The body was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 9]
In Example 9, a single layer type electrophotographic photosensitive member was used in the same manner as in Example 7 except that the compound (ETM-2) represented by the following formula (8) was used as the electron transport agent when forming the photosensitive layer. The body was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 10]
In Example 10, when forming the photosensitive layer, a single layer type electrophotographic photosensitive member was used in the same manner as in Example 7 except that the compound (ETM-3) represented by the following formula (9) was used as the electron transfer agent. The body was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 11]
In Example 11, when forming the photosensitive layer, a single-layer electrophotography was used in the same manner as in Example 7 except that the compound (HTM-2) represented by the following formula (10) was used as the hole transport agent. A photoconductor was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 12]
In Example 12, when forming the photosensitive layer, a single layer type electrophotographic image was obtained in the same manner as in Example 7 except that the compound (HTM-3) represented by the following formula (11) was used as the hole transport agent. A photoconductor was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 13]
Example 13 was the same as Example 7 except that (MT-100SA) (number average primary particle size: 15 nm) manufactured by Teika Co., Ltd. was used as the titanium oxide fine particles surface-treated with silica and alumina. A layer-type electrophotographic photosensitive member was produced and evaluated. The obtained results are shown in Table 1.

[Example 14]
Example 14 was the same as Example 7 except that (MT-500SA) (number average primary particle diameter: 30 nm) manufactured by Teika Co., Ltd. was used as the titanium oxide fine particles surface-treated with silica and alumina. A layer-type electrophotographic photosensitive member was produced and evaluated. The obtained results are shown in Table 1.

[Example 15]
In Example 15, single layer electrophotography was performed in the same manner as in Example 7 except that X4585 (low molecular weight product of X1010) manufactured by Daicel Degussa Co., Ltd. was used as the copolymer nylon as the binder resin in the intermediate layer. A photoconductor was manufactured and evaluated. The obtained results are shown in Table 1.

[Example 16]
In Example 16, a single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 7 except that the content of the titanium oxide fine particles in the intermediate layer was changed to 120 parts by weight. The obtained results are shown in Table 1.

[Example 17]
In Example 17, a single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 7 except that the content of the titanium oxide fine particles in the intermediate layer was changed to 200 parts by weight. The obtained results are shown in Table 1.

[Example 18]
In Example 18, a single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 7 except that the content of the titanium oxide fine particles in the intermediate layer was changed to 380 parts by weight. The obtained results are shown in Table 1.

[Example 19]
In Example 19, a single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 7 except that dimethylpolysiloxane (DMPS) was used when the surface treatment was performed on the titanium oxide fine particles. . The obtained results are shown in Table 1.

[Comparative Example 1]
In Comparative Example 1, a single-layer electrophotographic photosensitive member was produced in the same manner as in Example 6 except that when titanium oxide fine particles were subjected to surface treatment, the surface treatment with methylhydrogenpolysiloxane was not performed. ,evaluated. The obtained results are shown in Table 1.

[Comparative Example 2]
In Comparative Example 2, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 6 except that the amount of methyl hydrogen polysiloxane added was changed to 4 parts by weight when the surface treatment was performed on the titanium oxide fine particles. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Comparative Example 3]
In Comparative Example 3, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 6 except that the amount of methyl hydrogen polysiloxane added was changed to 6 parts by weight when the surface treatment was performed on the titanium oxide fine particles. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Comparative Example 4]
In Comparative Example 4, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 6 except that the amount of methyl hydrogen polysiloxane added was changed to 10 parts by weight when the surface treatment was performed on the titanium oxide fine particles. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Comparative Example 5]
In Comparative Example 5, a single-layer electrophotographic photosensitive member was produced in the same manner as in Example 1 except that when the surface treatment was performed on the titanium oxide fine particles, the surface treatment with methylhydrogenpolysiloxane was not performed. ,evaluated. The obtained results are shown in Table 1.

[Comparative Example 6]
In Comparative Example 6, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the amount of methyl hydrogen polysiloxane added was changed to 10 parts by weight when the surface treatment was performed on the titanium oxide fine particles. It was manufactured and evaluated. The obtained results are shown in Table 1.

According to the single layer type electrophotographic photosensitive member and the image forming apparatus according to the present invention, in the single layer type electrophotographic photosensitive member, an intermediate layer is provided between the substrate and the photosensitive layer, and the intermediate layer is specified. By including the titanium oxide fine particles, it has become possible to eliminate the environmental dependence of the photoreceptor characteristics.
As a result, the generation of black spots in a high temperature and high humidity environment can be effectively suppressed, while excellent sensitivity characteristics can be effectively maintained even in a low temperature and low humidity environment.
Therefore, the single-layer type electrophotographic photosensitive member and the image forming apparatus according to the present invention are expected to significantly contribute to the improvement of quality in image forming apparatuses such as copying machines and printers.

10: single layer type electrophotographic photosensitive member, 12: substrate, 14: photosensitive layer, 16: intermediate layer, 100: image forming apparatus, 102: static eliminating means, 112: charging means, 113: exposure means, 114: developing means, 115: Transfer means, 117: Cleaning device, 120: Recording paper

Claims (10)

A single-layer electrophotographic photosensitive member comprising an intermediate layer and a photosensitive layer on a substrate,
The intermediate layer contains a binder resin and titanium oxide fine particles, and the titanium oxide fine particles have the following characteristics (a) to (c).
(A) The number average primary particle diameter of the titanium oxide fine particles is a value within a range of 5 to 30 nm.
(B) Titanium oxide fine particles are surface-treated with alumina, silica and an organosilicon compound.
(C) The weight ratio X (wt%) of the organosilicon compound on the surface of the titanium oxide fine particles satisfies the following relational expression (1).
1 (% by weight) ≦ X <4 (% by weight) (1) 2. The single-layer electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a titanyl phthalocyanine crystal having the following characteristics (A) and (B) as a charge generating agent.
(A) In a CuKα characteristic X-ray diffraction spectrum, it has a main peak at a Bragg angle of 2θ ± 0.2 ° = 27.2 °.
(B) In differential scanning calorimetry, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.   The single-layer electrophotographic photosensitive member according to claim 1 or 2, wherein the surface treatment with the organosilicon compound is performed on the surface treatment layer with the alumina and silica.   4. The content of the titanium oxide fine particles is set to a value within a range of 120 to 450 parts by weight with respect to 100 parts by weight of the binder resin of the intermediate layer. 1. A single-layer electrophotographic photosensitive member according to 1.   The single-layer electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the binder resin of the intermediate layer is a polyamide resin.   The single-layer electrophotographic photosensitive member according to claim 1, wherein the thickness of the intermediate layer is set to a value within a range of 0.1 to 50 μm.   A single-layer electrophotographic photosensitive member according to any one of claims 1 to 6, and a charging unit, a developing unit, a transfer unit, a cleaning unit, and a neutralizing unit around the single-layer type electrophotographic photosensitive member. An image forming apparatus.   The image forming apparatus according to claim 7, wherein the cleaning unit is a cleaning unit that employs a roller cleaning system that polishes the surface of the single-layer electrophotographic photosensitive member with a roller member.   9. The image forming apparatus according to claim 7, wherein the charging unit is a charging unit that charges the surface of the single-layer electrophotographic photosensitive member to a positive polarity.   The image forming apparatus according to claim 7, wherein a peripheral speed of the single-layer electrophotographic photosensitive member is set to a value of 100 mm / sec or more.