JP7351131B2 - Electrophotographic photoreceptor and electrophotographic image forming device - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor and an electrophotographic image forming apparatus, and more particularly to an electrophotographic photoreceptor and an electrophotographic image forming apparatus that can improve scratch resistance and suppress image blur and point defects.

In recent years, electrophotographic image forming devices such as copiers and printers are required to have even higher durability and higher image quality, and electrophotographic photoreceptors are also required to have higher durability and higher image quality. A response is needed. Demand for higher durability is also increasing in order to contribute to the realization of a sustainable society. Mechanical strength such as abrasion resistance and scratch resistance, which is the biggest factor determining the durability life of a photoreceptor, is particularly important. On the other hand, with regard to high image quality, it is necessary to be able to maintain image quality over a long period of time.

However, when using a photoreceptor for a long period of time, the image quality may deteriorate due to deterioration due to discharge products, etc., and simply improving the mechanical strength may make it difficult to remove deposits such as discharge products. A problem arises in that image blur and the like are more likely to occur.

Therefore, as a countermeasure against image blur and scratch resistance, a technique is known in which a monomer is used in combination. For example, Patent Document 1 proposes the combined use of dicyclopentanyl (meth)acrylate, which is a monofunctional monomer, and pentaerythritol tetra(meth)acrylate, which is a tetrafunctional monomer. However, when a monofunctional monomer is used, the crosslinking density becomes insufficient and it becomes difficult to obtain sufficient film strength, which causes problems in ensuring scratch resistance during long-term use.

There has also been a proposal to use a polyfunctional radically polymerizable monomer modified with alkylene oxide in combination with a polyfunctional radically polymerizable monomer that is not modified with alkylene oxide (for example, see Patent Document 2). However, when two types of polyfunctional monomers are polymerized, there is a tendency for the number of unreacted polymerizable groups to increase because the reactivity may decrease as radical polymerization progresses. In addition, if there are many polymerizable groups and the monomer has an alkylene oxide moiety, it tends to inhibit compatibility with the inorganic filler, so that aggregation of the inorganic filler is likely to occur. As a result, the resistance of the outermost layer becomes locally low, causing image defects (point defects) in which dots are printed even in non-printing areas, and especially when the printing speed is high and the area of the image area is large. (high coverage), the scratch resistance may deteriorate, and in addition, discharge products tend to adhere to the alkylene oxide site, making it difficult to achieve the effect of suppressing image blurring when used for a long period of time. I end up.

In addition, proposals have been made to suppress image blurring and reduce the amount of wear on the photoreceptor by reducing the amount of unreacted acryloyl groups without simply using a curable material with fewer acryloyl groups (for example, see Patent Document 3). ). However, since urethane acrylate is used as a bifunctional monomer, highly hydrophilic elements such as nitrogen and oxygen are present between the two acryloyloxy groups, making it easier for discharge products to adhere, resulting in image blurring. The durability of the suppressive effect will be poor. Furthermore, the compatibility with inorganic fillers deteriorates, making it easier for inorganic fillers to aggregate, which tends to cause point defects due to localized decreases in the resistance of the outermost layer, and especially at high printing speeds. Scratch resistance deteriorates when coverage is high.

Japanese Patent Application Publication No. 4-37765 Japanese Patent Application Publication No. 2018-112675 Japanese Patent Application Publication No. 2008-76943

The present invention has been made in view of the above problems and circumstances, and an object to be solved is to provide an electrophotographic photoreceptor and an electrophotographic image that can improve scratch resistance and suppress image blur and point defects. An object of the present invention is to provide a forming device.

In order to solve the above-mentioned problems, the present inventors, in the process of studying the causes of the above-mentioned problems, discovered that the outermost layer was made of a trifunctional or higher functional polymerizable monomer, a bifunctional monomer having a specific structure, and a surface modification treatment. By using a polymerizable cured product containing an inorganic filler, it is possible to provide an electrophotographic photoreceptor and an electrophotographic image forming apparatus that can improve scratch resistance and suppress image blur and point defects. This discovery led to the present invention.
That is, the above-mentioned problems related to the present invention are solved by the following means.

1. An electrophotographic photoreceptor having a curable outermost layer,
The outermost layer includes at least a first polymerizable monomer having three or four polymerizable groups in one monomer molecule, and a second polymerizable monomer having two polymerizable groups in one monomer molecule, A polymerizable cured product containing an inorganic filler treated with a surface modifier, and
An electrophotographic photoreceptor, wherein the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via a hydrocarbon.

2. 2. The electrophotographic photoreceptor according to item 1, wherein the surface modifier has a silicone chain.

3. 3. The electrophotographic photoreceptor according to item 1 or 2, wherein the inorganic filler treated with the surface modifier has a polymerizable group.

4. The electrophotographic photoreceptor according to any one of Items 1 to 3, wherein the surface modifier has a silicone chain in a side chain.

5. 5. The electrophotographic photoreceptor according to item 4, wherein the surface modifier having a silicone chain in its side chain has a silicone side chain branched from an acrylic main chain.

6. 5. The electrophotographic photoreceptor according to item 4, wherein the surface modifier having a silicone chain in its side chain has a silicone side chain branched from a silicone main chain.

7 . The electrophotography according to any one of Items 1 to 6 , wherein the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via an alkylene group. Photoreceptor.

8 . The electronic device according to any one of Items 1 to 7 , wherein the content of the second polymerizable monomer is within the range of 30 to 70% by mass based on the total monomers. Photographic photoreceptor.
9. An electrophotographic photoreceptor having a curable outermost layer,
The outermost layer comprises at least a first polymerizable monomer having three or more polymerizable groups in one monomer molecule, a second polymerizable monomer having two polymerizable groups in one monomer molecule, and surface modification. A polymerizable cured product containing an inorganic filler treated with an agent, and
An electrophotographic photoreceptor, wherein the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via an alkylene group.

10. An electrophotographic image forming apparatus comprising the electrophotographic photoreceptor according to any one of items 1 to 9.

By the means of the present invention, it is possible to provide an electrophotographic photoreceptor and an electrophotographic image forming apparatus that can improve scratch resistance and suppress image blur and point defects.
Although the mechanism of expression or action of the effects of the present invention is not clear, it is speculated as follows.
The mechanism of image blurring is that discharge products such as ozone and nitrogen oxides generated by charging adhere to the surface of the photoreceptor and combine with moisture (humidity), causing a decrease in the surface resistance of the photoreceptor and It is assumed that the products cause oxidative deterioration of the photoreceptor, making it difficult to maintain the latent image and causing image blurring. It tends to adhere to highly reactive areas.
Therefore, it is thought that image blurring can be suppressed by making it possible to remove discharge products even if they adhere or by making it difficult for discharge products to adhere.
As a method for removing the adhered discharge products, there is a method of reducing the strength of the outermost layer of the photoreceptor and scraping the outermost layer to which the discharge products have adhered. However, this method deteriorates the scratch resistance.
On the other hand, as a method for making it difficult for discharge products to adhere, there is a method of reducing the portions of the outermost layer of the photoreceptor where discharge products tend to adhere, that is, reactive sites such as unreacted sites of polymerization. It is known that increasing the reaction rate of monomers is effective in reducing the number of unreacted sites during polymerization.
The unreacted sites of the monomer can be reduced by polymerizing monomers with a small number of functional groups, such as monofunctional monomers and bifunctional monomers. However, in the case of monofunctional monomers or bifunctional monomers, the film strength tends to be inferior compared to the case where polyfunctional monomers having three or more functionalities are polymerized.
Therefore, in order to use it in the outermost layer of an electrophotographic photoreceptor that both ensures scratch resistance and suppresses image blurring, it has been found that it is good to use a trifunctional or higher polyfunctional monomer and a bifunctional monomer in combination.
In addition, from the viewpoint of suppressing the adhesion of discharge products, which are considered to be a factor in causing image blur, it is preferable that the bifunctional monomer has a highly hydrophobic site or a bulky site, and such a site may be introduced. By doing this, it is possible to reduce the portions of the outermost layer of the photoreceptor where discharge products tend to adhere, that is, more hydrophilic regions, and to create a condition in which discharge products are difficult to physically approach due to steric hindrance caused by bulky regions. It becomes possible to do so. Therefore, it has been found that the bifunctional monomer preferably has a structure in which two polymerizable groups are bonded via a hydrocarbon.
In this way, by having a structure in which two polymerizable groups are bonded via a hydrocarbon, it is possible to combine two polymerizable groups into a bifunctional monomer, compared to the case where urethane acrylate is used as disclosed in Patent Document 3. The content of elements other than carbon and hydrogen, such as nitrogen and oxygen, can be reduced, and the number of more hydrophilic sites in the bifunctional monomer can be reduced. As a result, the number of highly hydrophobic sites increases, so that it is possible to more effectively suppress the adhesion of discharge products, which are thought to be a cause of image blurring. In addition, since the compatibility with the surface-modified inorganic filler increases, it is thought that the dispersibility of the inorganic filler also improves, resulting in good scratch resistance and suppression of point defects.
Further, by subjecting the inorganic filler to surface modification treatment, the dispersibility is improved, so it is possible to suppress aggregation of the inorganic filler. In this respect as well, it is possible to improve the scratch resistance and suppress point defects.
As described above, it is assumed that by using a polyfunctional monomer or a bifunctional monomer with a specific structure in combination with an inorganic filler that has undergone surface modification treatment, it is possible to improve scratch resistance and suppress image blur and point defects. be done.

A sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention A schematic diagram showing an example of the overall configuration of a tandem-type electrophotographic image forming apparatus including an electrophotographic photoreceptor of the present invention. A schematic diagram showing an example of the configuration of a fine particle manufacturing apparatus used for manufacturing composite particles used in Examples of the present invention A schematic diagram for explaining the evaluation method of a photoreceptor in an example of the present invention A schematic diagram for explaining the evaluation method of a photoreceptor in an example of the present invention

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a curable outermost layer, wherein the outermost layer is made of at least a first polymerizable monomer having three or more polymerizable groups in one monomer molecule. , a second polymerizable monomer having two polymerizable groups in one molecule of the monomer, and an inorganic filler treated with a surface modifier; The polymerizable monomer is characterized in that it has a structure in which the two polymerizable groups are bonded via a hydrocarbon.
This feature is a technical feature common to or corresponding to each of the embodiments described below.

In an embodiment of the present invention, the surface modifier having a silicone chain effectively hydrophobizes the surface of the inorganic filler and improves compatibility with the first and second polymerizable monomers. This is preferable because the dispersibility is improved and, as a result, the scratch resistance and the effect of suppressing point defects are improved.

Further, it is preferable that the inorganic filler treated with the surface modifier has a polymerizable group, since an outermost layer with more excellent scratch resistance can be formed.

In addition, the fact that the surface modifier has a silicone chain in its side chain effectively makes the surface of the inorganic filler hydrophobic, improves compatibility with the first and second polymerizable monomers, and improves dispersibility. This is preferable because it improves performance.

In addition, the surface modifier having a silicone chain in its side chain has a silicone side chain branched from an acrylic main chain, or the surface modifier having a silicone chain in its side chain has a silicone side chain branched from a silicone main chain. It is preferable to have a side chain because the dispersibility of the inorganic filler is further increased and the scratch resistance is further improved.

It is preferable that the first polymerizable monomer has three polymerizable groups in one molecule of the monomer, from the viewpoint of improving the reaction rate and compatibility with the inorganic filler.

Furthermore, the fact that the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via an alkylene group not only makes it possible to more effectively increase the compatibility with the filler but also to reduce brittleness. This is preferable in that it can further improve scratch resistance because there are no rigid parts that tend to cause damage.

Further, when the content of the second polymerizable monomer is within the range of 30 to 70% by mass based on the total monomers, the reaction rate can be improved and the effect of suppressing image blurring can be exhibited. This is preferable because sufficient film strength can be ensured without reducing the crosslinking density, and the effect on scratch resistance can also be exhibited.

The electrophotographic photoreceptor of the present invention is suitably used in an electrophotographic image forming apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, its constituent elements, and forms and aspects for carrying out the present invention will be described below. In this application, "~" is used to include the numerical values described before and after it as a lower limit value and an upper limit value.

《Electrophotographic photoreceptor》
[Basic configuration of electrophotographic photoreceptor]
The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a curable outermost layer, wherein the outermost layer is made of at least a first polymerizable monomer having three or more polymerizable groups in one monomer molecule. , a second polymerizable monomer having two polymerizable groups in one molecule of the monomer, and an inorganic filler treated with a surface modifier; The polymerizable monomer is characterized in that it has a structure in which the two polymerizable groups are bonded via a hydrocarbon.

FIG. 1 is a sectional view showing an example of the structure of an electrophotographic photoreceptor of the present invention.

The electrophotographic photoreceptor (hereinafter also simply referred to as "photoreceptor") of the present invention has at least a curable outermost layer having the structure defined in the present invention.

FIG. 1(a) is a cross-sectional view showing an electrophotographic photoreceptor 101A having a first configuration, in which an intermediate layer 103 is formed on a conductive support 102, a photosensitive layer 104 is provided thereon, and the In a configuration in which the outermost layer 105 according to the present invention is formed on the surface, the outermost layer 105 contains at least a first polymerizable monomer having three or more polymerizable groups in one monomer molecule; Contains a second polymerizable monomer having two in one monomer molecule and having a structure in which the two polymerizable groups are bonded via a hydrocarbon, and an inorganic filler treated with a surface modifier. It is composed of a polymerizable cured product.

Further, FIG. 1(b) is a cross-sectional view showing an electrophotographic photoreceptor 101B having a second configuration, in which an intermediate layer 103 is formed on a conductive support 102, and a charge generation layer 106 and a charge generation layer 106 are formed on the intermediate layer 103. A photosensitive layer 104 composed of a charge transport layer 107 is formed, and on the outermost surface, at least the first polymerizable monomer, the second polymerizable monomer, and an inorganic filler treated with a surface modifier. It has an outermost layer 105 made of a polymerizable cured product containing .

[Components of electrophotographic photoreceptor]
Below, details of the main components of the electrophotographic photoreceptor of the present invention will be explained.

[1. outermost layer]
The outermost layer according to the present invention includes at least a first polymerizable monomer having three or more polymerizable groups in one monomer molecule, and a first polymerizable monomer having two polymerizable groups in one monomer molecule, and It is composed of a polymerizable cured product containing a second polymerizable monomer having a structure in which functional groups are bonded via hydrocarbons, and an inorganic filler treated with a surface modifier.

Hereinafter, details of each component of the outermost layer according to the present invention will be explained.
The first and second polymerizable monomers according to the present invention have a polymerizable group, and are polymerized (cured) by irradiation with actinic rays such as ultraviolet rays, visible light, and electron beams, or by application of energy such as heating. It is a compound that becomes a resin that is generally used as a binder resin for photoreceptors. The polymerizable monomer is preferably a radically polymerizable monomer that is cured through a radical polymerization reaction.
Examples of the first and second polymerizable monomers include styrene monomers, acrylic monomers, methacrylic monomers, vinyltoluene monomers, vinyl acetate monomers, and N-vinylpyrrolidone monomers.As the binder resin, Examples of the material include polystyrene, polyacrylate, and the like.
The polymerizable groups possessed by the first and second polymerizable monomers have a carbon-carbon double bond and are polymerizable groups. The polymerizable group is preferably an acryloyloxy group (CH ₂ =CHCOO-) or a methacryloyloxy group (CH ₂ =C(CH ₃ )COO-) because it can be cured with a small amount of light or in a short time. preferable.
The first and second polymerizable monomers can be synthesized by known methods, and can also be obtained as commercially available products.

(First polymerizable monomer)
The first polymerizable monomer is a polyfunctional monomer having three or more polymerizable groups in one monomer molecule.
Specific examples of the first polymerizable monomer include, but are not limited to, the following compounds M1 to M12. In the following formulas, R represents an acryloyloxy group, and R' represents a methacryloyloxy group.

The first polymerizable monomer is preferably a monomer having three polymerizable groups from the viewpoint of improving the reaction rate and compatibility with the inorganic filler.
Moreover, it is preferable that the site|part which connects the polymeric group of a 1st polymerizable monomer is a hydrocarbon. When the connecting part is hydrocarbon, it becomes more hydrophobic, which not only makes it possible to more effectively suppress the adhesion of discharge products, which are thought to be a cause of image blurring, but also improves compatibility with inorganic fillers. It is thought that the dispersibility of the inorganic filler also improves.

(Second polymerizable monomer)
The second polymerizable monomer is a bifunctional monomer having two polymerizable groups in one molecule of the monomer, and has a structure in which the two polymerizable groups are bonded via a hydrocarbon.
By using the first polymerizable monomer and the second polymerizable monomer, which is a bifunctional monomer, it is possible to increase the reaction rate of the polymerization reaction, and the discharge products that are thought to be the cause of image blurring are attached. This makes it possible to reduce unreacted sites that are susceptible to polymerization. Although it is possible to increase the polymerization reaction rate in the unreacted sites even when a monofunctional monomer is used in combination, the crosslinking density decreases significantly and it becomes difficult to ensure sufficient membrane strength.

In addition, from the viewpoint of suppressing the adhesion of discharge products, which are considered to be a factor causing image blurring, it is preferable that the second polymerizable monomer has a highly hydrophobic site or a bulky site. By introducing the sites, it is possible to reduce the sites on the photoreceptor surface layer where discharge products tend to adhere, that is, more hydrophilic sites, and it is difficult for discharge products to physically approach due to steric hindrance caused by bulky sites. It is possible to create a state.
Therefore, the second polymerizable monomer has a structure in which the two polymerizable groups are bonded via a hydrocarbon.
The hydrocarbon may be a divalent base hydrocarbon formed from a linear or branched alkyl group such as an alkylene group, or a divalent hydrocarbon formed from a cycloalkylene group, an arylene group, or a divalent residue of a polycyclic group. Cyclic divalent hydrocarbons such as these may also be used. It may also be a combination of a divalent base hydrocarbon formed from a linear or branched alkyl group and a cyclic divalent hydrocarbon.
Examples of the alkylene group include linear or branched alkylene groups having 1 to 12 carbon atoms (preferably 3 to 12 carbon atoms, more preferably 3 to 10 carbon atoms).
Specific examples of linear alkylene groups include methylene group, ethylene group, n-propylene group, n-butylene group, n-pentylene group, n-hexylene group, n-heptylene group, n-octylene group, n- Examples include nonylene group, n-decylene group, n-undecylene group, n-dodecylene group, and the like.
Specifically, the branched alkylene group includes an isopropylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, an isopentylene group, a neopentylene group, a tert-pentylene group, an isohexylene group, a sec-hexylene group, and a tert-hexylene group. group, isoheptylene group, sec-heptylene group, tert-heptylene group, isooctylene group, sec-octylene group, tert-octylene group, isononylene group, sec-nonylene group, tert-nonylene group, isodecylene group, sec-decylene group, tert -decylene group, isoundecylene group, sec-undecylene group, tert-undecylene group, neooundecylene group, isododecylene group, sec-dodecylene group, tert-dodecylene group, neododecylene group and the like.
Among these, linear alkylene groups such as n-butylene group, n-hexylene group, n-heptylene group, n-octylene group, n-nonylene group, and n-decylene group are preferable as the alkylene group.
Examples of the cycloalkylene group include cycloalkylene groups having 3 to 12 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 10 carbon atoms).
Specific examples of the cycloalkylene group include a cyclopropylene group, a cyclopentylene group, a cyclohexylene group, a cyclooctylene group, and a cyclododecanylene group.
Among these, a cyclohexylene group is preferred as the cycloalkylene group.
The divalent residue of a polycyclic group includes a divalent residue of a polycyclic group having 7 to 20 carbon atoms (preferably 7 to 18 carbon atoms, more preferably 7 to 15 carbon atoms); can be mentioned.
Specific examples of divalent residues of polycyclic groups include divalent residues such as tricyclodecanylene group, tetracyclododecanylene group, norbornylene group, and divalent residues such as adamantylene group. be able to. Among these, tricyclodecanylene group is preferred as the divalent residue of the polycyclic group.

A preferred structure of such a second polymerizable monomer includes a structure in which two (meth)acryloyloxy groups are bonded via the hydrocarbon, and more preferably a structure in which the hydrocarbon is an alkylene group. It will be done.

The second polymerizable monomer, which has a structure in which two polymerizable groups are bonded via a hydrocarbon, contains a small amount of elements other than carbon and hydrogen, such as nitrogen and oxygen, so that it can be easily removed from the monomer. The number of sites that become more hydrophilic can be reduced. As a result, the number of highly hydrophobic sites increases, so that it is possible to more effectively suppress the adhesion of discharge products, which are thought to be a cause of image blurring. In addition, since the compatibility with the surface-modified inorganic filler described later is increased, it is thought that the dispersibility of the inorganic filler is also improved. The compatibility with the surface-modified inorganic filler increases when an alkylene group is introduced as the hydrocarbon, and since there are no rigid parts that tend to become brittle, the compatibility with the surface-modified inorganic filler is particularly high at high printing speeds and in the image area. The scratch resistance is good even when the area is wide (high coverage).

Note that even if a highly hydrophobic site or a bulky site is introduced into the trifunctional or higher polyfunctional monomer, the adhesion of discharge products can be suppressed. However, when a highly hydrophobic moiety is introduced into a trifunctional or higher polyfunctional monomer, there are many polymerizable groups, so the compatibility with inorganic fillers, which is the effect of introducing a highly hydrophobic moiety, is inhibited by the polymerizable groups. There is a tendency to As a result, the dispersibility of the inorganic filler is reduced, and the effect of scratch resistance and point defect suppression is weakened. On the other hand, when a bulky moiety is introduced into a trifunctional or higher polyfunctional monomer, radical polymerization is also likely to be inhibited. As a result, the reaction rate decreases and the number of unreacted polymerizable groups increases, increasing the probability of reaction with discharge products and causing image blurring and point defects. Furthermore, the reduction in crosslinking density causes a reduction in membrane strength, which is an advantage of polyfunctional monomers.

Examples of the second polymerizable monomer include bifunctional alkyl (meth)acrylate, tricyclodecanol (meth)acrylate, and the like.
Specific examples of commercially available second polymerizable monomers include the following compounds.
Alkyl (meth)acrylate: A-HD-N, A-NOD-N, NPG, BD, HD-N, DOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.), SR206, SR213 (manufactured by Sartomer) ), FA-129AS (manufactured by Hitachi Chemical Co., Ltd.), KAYARAD NPGDA, etc., tricyclodecanol (meth)acrylate: DCP (manufactured by Shin-Nakamura Chemical Co., Ltd.), SR833S (manufactured by Sartomer), etc. .

The ratio of the first polymerizable monomer to the second polymerizable monomer can be adjusted as appropriate within a range that allows the electrophotographic photoreceptor to achieve the effects of this embodiment.
The content of the second polymerizable monomer is preferably within the range of 25 to 75% by mass, and 30 to 70% by mass based on the total polymerizable monomers, from the viewpoint of exhibiting the effect of the second polymerizable monomer. It is more preferably within the range of 35% to 65% by mass, and even more preferably within the range of 35 to 65% by mass. When the content of the second polymerizable monomer is 25% by mass or more, it greatly contributes to improving the reaction rate and has a large effect of suppressing image blur. On the other hand, when the content of the second polymerizable monomer is 75% by mass or less, the crosslinking density is high, the membrane strength is sufficiently ensured, and the scratch resistance is excellent.

(Inorganic filler)
The inorganic filler applied to the outermost layer according to the present invention is treated with a surface modifier.

Inorganic fillers applicable to the present invention are not particularly limited, but examples include magnesium oxide, lead oxide, aluminum oxide, zinc oxide, tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, Examples include copper, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium dioxide, niobium oxide, molybdenum oxide, vanadium oxide, copper-aluminum composite oxide, and antimony-doped tin oxide. . Among them, aluminum oxide (Al ₂ O ₃ ), tin oxide (SnO ₂ ), titanium dioxide (TiO ₂ ), and copper-aluminum composite oxide (CuAlO ₂ ) are preferable.

The above-mentioned inorganic filler may be used alone or in combination of two or more types. Further, the inorganic filler may be a synthetic product or a commercially available product.

<Composite particles with core-shell structure>
The inorganic filler according to the present invention may be a composite fine particle formed by adhering a conductive metal oxide to the surface of a core material made of an insulating material. That is, the inorganic filler may be a composite fine particle having a core-shell structure, in which the inorganic filler has a shell made of the inorganic filler as described above on the surface of a core made of an insulating material.

Examples of the core material constituting the composite particles having the core-shell structure include barium sulfate, aluminum oxide, and silica.
Preferred examples of composite fine particles with a core-shell structure include composite particles having a core material made of barium sulfate and an outer shell made of tin oxide. Note that the ratio between the number average primary particle diameter of the core material and the thickness of the outer shell may be appropriately set depending on the types of the core material and outer shell used, and the combination thereof.

<Treatment of inorganic filler with surface modifier>
The inorganic filler treated with a surface modifier according to the present invention is obtained by treating an untreated raw material inorganic filler with a surface modifier.

The inorganic filler treated with the surface modifier is considered to become a surface-coated filler containing the chemical species (coating layer) derived from the surface modifier and the inorganic filler. Note that the surface-modified inorganic filler only needs to have a chemical species (coating layer) derived from the surface modifier on at least a portion of its surface.

When an inorganic filler is treated with a surface modifier, the inorganic filler is effectively made hydrophobic. When a composition is prepared using the inorganic filler subjected to the surface modification treatment and the first and second polymerizable monomers, and the outermost layer of the photoreceptor is formed with the polymerized and cured product, the surface modification treatment is performed. The resulting inorganic filler has improved compatibility with the first and second polymerizable monomers, which is advantageous for dispersibility.

In the present invention, the surface modifier applied to the surface modification treatment of the inorganic filler is not particularly limited as long as it is a compound that makes the surface of the inorganic filler hydrophobic, and conventionally known agents can be used.
Specific examples of the surface modifier include silane coupling agents, titanium coupling agents, fluorine-based surface modifiers, and surface modifiers having silicone chains.

In the present invention, from the viewpoint of dispersibility, the surface modifier is preferably a fluorine-based or one having a silicone chain, more preferably a surface modifier having a silicone chain, and furthermore, a surface modifier having a silicone chain is preferable, and furthermore, a surface modifier having a silicone chain is preferable, and furthermore, a surface modifier having a silicone chain is preferable from the viewpoint of dispersibility. A surface modifier having a silicone chain in its side chain, that is, a surface modifier having a silicone chain in its side chain. Further, it is preferable that the surface modifier having a silicone chain in its side chain has a silicone side chain branched from an acrylic main chain, or a silicone side chain branched from a silicone main chain.

When a surface modifier having a silicone chain is used, the inorganic filler is more efficiently hydrophobicized, and the effect of improving compatibility with the polymerizable monomer and antioxidant is more exerted. In particular, when treated with a surface modifier having a silicone chain in its side chain, a high concentration of silicone chains will be present on the surface of the inorganic filler. When silicone chains are present at a high concentration on the surface, a composition is prepared using a surface-modified inorganic filler and the first and second polymerizable monomers, and the polymerizable cured product is This is advantageous for dispersibility when forming the surface layer of a photoreceptor.

As a surface modifier having a silicone chain in the side chain, the main chain of the polymer may be a poly(meth)acrylic acid ester copolymer chain or a poly( A meth)acrylate main chain (also simply referred to as "acrylic main chain") or a silicone main chain is preferred from the viewpoint of further improving dispersibility. When the dispersibility of the inorganic filler in the outermost layer increases, aggregation of the inorganic filler becomes less likely to occur, and the wear resistance, scratch resistance, etc. of the outermost layer are further improved.

In the above general formula (2), R is a hydrogen atom or a methyl group, and R' represents an alkyl group having 1 to 6 carbon atoms.

The silicone chain constituting the side chain and the main chain preferably has a dimethylsiloxane structure as a repeating unit, and the number of repeating units in both the side chain and the main chain is preferably 3 to 100. It is more preferable that the number is between 50 and 30, and even more preferably between 3 and 30. If the number of repeating units in both the side chain and the main chain is 3 or more, the effect of the silicone surface modification treatment can be effectively expressed, and if it is 100 or less, the first and second polymerization It has good compatibility with chemical monomers, and has excellent dispersibility without agglomeration or sedimentation.
The acrylic chain of the main chain preferably has the structure derived from the monomer shown above as a repeating unit, and the number of repeating units is preferably 3 to 100, more preferably 3 to 50, More preferably, the number is 3 to 30. If the number of repeating units is 3 or more, the effect of the silicone surface modification treatment can be effectively expressed, and if it is 100 or less, it has good compatibility with the first and second polymerizable monomers, resulting in aggregation. - Excellent dispersibility without settling.

The surface modifiers can be used alone or in combination of two or more. Further, the surface modifier may be a synthetic product or a commercially available product. Specific examples of commercially available surface modifiers include the following compounds.

Silane coupling agent: KBM-502, KBM-503, KBM-5103, KBE-502 (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.
Titanium coupling agent: Orgatics TC-800 (manufactured by Matsumoto Fine Chemicals Co., Ltd.), etc.
Fluorine-based surface modifiers: Novec1700, Novec1720, Novec2702 (manufactured by 3M Japan), etc.
Surface modifiers with silicone chains: KF-99, KF-9901 (manufactured by Shin-Etsu Chemical Co., Ltd.; linear chain type), Cymac US-350 (manufactured by Toagosei Co., Ltd.; side chain type, acrylic main chain), KP-541, KP-574, KP-578 (all manufactured by Shin-Etsu Chemical Co., Ltd.; side chain type acrylic main chain), KF-9908, KF-9909 (all manufactured by Shin-Etsu Chemical Co., Ltd.; side chain type, silicone main chain), etc.
can be mentioned.

<Inorganic filler with polymerizable group>
In the present invention, it is preferable that the inorganic filler treated with the applied surface modifier has a polymerizable group.
The polymerizable group has a carbon-carbon double bond and is a polymerizable group. The polymerizable groups that the inorganic filler may have may be one or more, and may be the same or different from each other, and the polymerizable groups that the polymerizable monomer forming the polymerizable cured product has may be the same or different. The inorganic filler having a polymerizable group can be obtained, for example, by treating the inorganic filler with a surface modifier made of a compound having a polymerizable group.

One preferred form is that the inorganic filler treated with the surface modifier according to the present invention has a polymerizable group.

When an inorganic filler having a polymerizable group is used, the inorganic filler and the first and second polymerizable monomers polymerize, making it easier to obtain mechanical strength and making it difficult for the inorganic filler to fall off, resulting in long-term effects. It becomes easier to perform.

Examples of compounds having a polymerizable group (reactive organic group-containing surface modifier) include the following.

S-1: CH ₂ =CHSi(CH ₃ )(OCH ₃ ) ₂
S-2: CH ₂ =CHSi(OCH ₃ ) ₃
S-3: _CH2 = _CHSiCl3
S-4: CH ₂ =CHCOO(CH ₂ ) ₂ Si(CH ₃ )(OCH ₃ ) ₂
S-5: CH ₂ =CHCOO(CH ₂ ) ₂ Si(OCH ₃ ) ₃
S-6: CH ₂ =CHCOO(CH ₂ ) ₂ Si(OC ₂ H ₅ )(OCH ₃ ) ₂
S-7: CH ₂ =CHCOO(CH ₂ ) ₃ Si(OCH ₃ ) ₃
S-8: CH ₂ =CHCOO(CH ₂ ) ₂ Si(CH ₃ )Cl ₂
S-9: CH ₂ =CHCOO(CH ₂ ) ₂ SiCl ₃
S-10: CH ₂ =CHCOO(CH ₂ ) ₃ Si(CH ₃ )Cl ₂
S-11: CH ₂ =CHCOO(CH ₂ ) ₃ SiCl ₃
S-12: _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _CH3 )( _OCH3 ) ₂
S-13: _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _OCH3 ) ₃
S-14: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _CH3 )( _OCH3 ) ₂
S-15: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _OCH3 ) ₃
S-16: _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _CH3 ) _Cl2
S-17: _CH2 =C( _CH3 ) _COO ( _CH2 ) _2SiCl3
S-18: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _CH3 ) _Cl2
S-19: _CH2 =C( _CH3 ) _COO ( _CH2 ) _3SiCl3
S-20: CH ₂ =CHSi(C ₂ H ₅ )(OCH ₃ ) ₂
S-21: _CH2 =C( _CH3 )Si( _OCH3 ) ₃
S-22: CH ₂ =C(CH ₃ )Si(OC ₂ H ₅ ) ₃
S-23: CH ₂ =CHSi(OC ₂ H ₅ ) ₃
S-24: _CH2 =C( _CH3 )Si( _CH3 )( _OCH3 ) ₂
S-25: CH ₂ =CHSi(CH ₃ )Cl ₂
S-26: CH ₂ =CHCOOSi(OCH ₃ ) ₃
S-27: CH ₂ = CHCOOSi(OC ₂ H ₅ ) ₃
S-28: _CH2 =C( _CH3 )COOSi( _OCH3 ) ₃
S- ₂₉ : _CH2 =C( _CH3 )COOSi( _OC2H5 ) ₃
S- ₃₀ : _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _OC2H5 ) ₃
S-31: CH ₂ =CHCOO(CH ₂ ) ₂ Si(CH ₃ ) ₂ (OCH ₃ )
S-32: _CH2 =C( _CH3 )COO( _CH2 ) _8Si ( _OCH3 ) ₃

<Shape of inorganic filler>
The shape of the inorganic filler is not particularly limited, and examples thereof include spherical, elliptical in cross section, needle, disc, and irregular shape. From the viewpoint of dispersibility, etc., a spherical shape or an elliptical cross-sectional shape is preferable.

<Characteristic values of inorganic filler>
The number average primary particle size of the inorganic filler is preferably within the range of 10 to 200 nm, more preferably within the range of 20 to 150 nm. If the number average primary particle size of the inorganic filler is 10 nm or more, sufficient scratch resistance can be obtained. On the other hand, if the number average primary particle size of the inorganic filler is 200 nm or less, when the inorganic filler is dispersed in a solvent during the formation of the outermost layer, the inorganic filler does not settle in the dispersion liquid, and the photoreceptor can be stably formed. can be manufactured.

The number average primary particle size of the inorganic filler is defined as the number average primary particle size measured by the following method.

First, a 10,000 times enlarged photograph of a sample (inorganic filler, etc.) taken with a scanning electron microscope (manufactured by JEOL Ltd.) is taken into a scanner.
Next, from the obtained photographic images, 300 inorganic filler images or particle images excluding aggregated inorganic fillers and particles were randomly processed using the automatic image processing analysis system Luzex AP Software Ver. 1.32 (manufactured by Nireco Co., Ltd.) to perform binarization processing to calculate the Feret diameter in the horizontal direction of each of the inorganic filler image or particle image. Then, the average value of the Feret diameter in the horizontal direction of each of the inorganic filler images or particle images is calculated and set as the number average primary particle diameter. Here, the horizontal direction Feret diameter refers to the length of the side parallel to the x-axis of the circumscribed rectangle when the inorganic filler image or particle image is binarized.
Furthermore, the measurement of the number average primary particle diameter of the inorganic filler is performed on an inorganic filler that does not contain a chemical species (coating layer) derived from a surface modifier. Even if the inorganic filler is subjected to surface modification treatment, it is thought that the thickness will be within the error range compared to the inorganic filler (roughly, the thickness is about 1/10000 of the inorganic filler diameter). It is assumed that there is no change in the average primary particle diameter by applying

Next, other constituent elements of the electrophotographic photoreceptor of the present invention will be explained.

[2. Conductive support]
The conductive support constituting the photoreceptor of the present invention is not particularly limited as long as it has conductivity; for example, metal such as aluminum, copper, chromium, nickel, zinc, stainless steel, etc. is formed into a drum or sheet shape. metal foil such as aluminum or copper laminated to a plastic film, aluminum, indium oxide, tin oxide, etc. deposited on a plastic film, and a conductive layer coated with a conductive substance alone or together with a binder resin. Examples include metals, plastic films, and paper.

[3. middle class]
In the photoreceptor of the present invention, an intermediate layer having a barrier function and an adhesive function can also be provided between the conductive support and the photosensitive layer. Considering various failure prevention and the like, it is preferable to provide an intermediate layer.

Such an intermediate layer contains, for example, a binder resin (hereinafter also referred to as "intermediate layer binder resin") and, if necessary, conductive particles or metal oxide particles.

The binder resin for the intermediate layer is not particularly limited, and examples thereof include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. Among these, alcohol-soluble polyamide resins are preferred. These intermediate layer binder resins may be used alone or in combination of two or more.

The intermediate layer can contain various conductive particles and metal oxide particles for the purpose of adjusting resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. Further, conductive particles (ultrafine particles) such as tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide can be used.

The number average primary particle size of such conductive particles or metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

These conductive particles or metal oxide particles may be used alone or in combination of two or more. When two or more types are mixed, they may be in the form of a solid solution or fusion.

The content of the conductive particles or metal oxide particles is preferably in the range of 20 to 400 parts by weight, more preferably in the range of 50 to 350 parts by weight, based on 100 parts by weight of the binder resin.

The thickness of the intermediate layer is preferably within the range of 0.1 to 15 μm, more preferably within the range of 0.3 to 10 μm.

[4. Photosensitive layer]
The photoreceptor of the present invention has a photosensitive layer between the intermediate layer and the outermost layer. More specifically, the photosensitive layer is composed of a charge generation layer and a charge transport layer.

(charge generation layer)
The charge generation layer in the photosensitive layer constituting the photoreceptor contains a charge generation substance and a binder resin (hereinafter also referred to as "binder resin for charge generation layer").

Examples of charge-generating substances include azo raw materials such as Sudan red and Diane blue, quinone pigments such as pyrenequinone and anthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and polypropylene such as pyranthrone and diphthaloylpyrene. Examples include, but are not limited to, ring quinone pigments and phthalocyanine pigments. Among these, polycyclic quinone pigments and titanyl phthalocyanine pigments are preferred. These charge generating substances may be used alone or in combination of two or more.

As the binder resin for the charge generation layer, known resins can be used, such as polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenolic resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (e.g., vinyl chloride-vinyl acetate copolymer resins, chlorinated Examples include, but are not limited to, vinyl-vinyl acetate-maleic anhydride copolymer resin), poly-vinyl carbazole resin, and the like. Among these, polyvinyl butyral resin is preferred. These binder resins for the charge generation layer may be used alone or in combination of two or more.

The content of the charge generating substance in the charge generating layer is preferably within the range of 1 to 600 parts by weight, more preferably within the range of 50 to 500 parts by weight, based on 100 parts by weight of the binder resin for the charge generating layer. It is.

The thickness of the charge generation layer varies depending on the characteristics of the charge generation substance, the characteristics of the binder resin for the charge generation layer, the content ratio, etc., but is preferably within the range of approximately 0.01 to 5 μm, more preferably 0.01 to 5 μm. It is within the range of 0.05 to 3 μm.

(charge transport layer)
The charge transport layer in the photosensitive layer constituting the photoreceptor contains a charge transport substance and a binder resin (hereinafter also referred to as "binder resin for charge transport layer").

Examples of the charge transporting substance in the charge transporting layer that transport charges (holes) include triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, and butadiene compounds.

The charge transport layer formed at the bottom of the outermost layer preferably contains a charge transport substance with high mobility and a large molecular weight, and known compounds can be used in combination as such charge transport substances. For example, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, etc. can be mentioned. These compounds can be used alone or in combination of two or more.

Known resins can be used as the binder resin for the charge transport layer, such as polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate ester resin, styrene-methacrylate ester. Examples include copolymer resins, but polycarbonate resins are preferred. Furthermore, BPA (bisphenol A) type, BPZ (bisphenol Z) type, dimethyl BPA type, BPA-dimethyl BPA copolymer type polycarbonate resins, etc. are preferable in terms of crack resistance, abrasion resistance, and charging characteristics. These binder resins for the charge transport layer may be used alone or in combination of two or more.

The content ratio of the charge transport substance in the charge transport layer is preferably within the range of 10 to 500 parts by mass, more preferably within the range of 20 to 250 parts by mass, based on 100 parts by mass of the binder resin for the charge transport layer. It is.

The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics and content ratio of the binder resin for the charge transport layer, but is preferably within the range of 5 to 40 μm, more preferably within the range of 10 to 30 μm. It is within.

Antioxidants, electronic conductive agents, stabilizers, silicone oil, etc. may be added to the charge transport layer. Preferably, the antioxidant is disclosed in JP-A-2000-305291, and the electronic conductive agent is disclosed in JP-A-50-137543, JP-A-58-76483, and the like.

《Method for manufacturing electrophotographic photoreceptor》
The method for producing the photoreceptor of the present invention includes the steps of forming an uncured film containing a polymerizable compound on a photosensitive layer on a conductive support, and irradiating the uncured film with light to form a cured resin. Although not particularly limited, it is preferably manufactured by a manufacturing method having the following steps, although not particularly limited.

Step (1): a step of forming an intermediate layer by applying a coating liquid for forming an intermediate layer on the outer peripheral surface of the conductive support and drying it;
Step (2): Apply a coating liquid for forming a charge generation layer to the outer peripheral surface of the conductive support or to the outer peripheral surface of the intermediate layer formed on the conductive support in step (1), and dry. forming a charge generation layer by,
Step (3): Applying a coating solution for forming a charge transport layer to the outer peripheral surface of the conductive support or the outer peripheral surface of the charge generation layer formed on the intermediate layer, and forming a charge transport layer by drying. process,
Step (4): A step of forming an outermost layer by applying a coating liquid for forming an outermost layer on the outer peripheral surface of the charge transport layer formed on the charge generation layer, polymerizing and curing the coating liquid.

The concentration of each component in the coating liquid for forming each layer is appropriately selected according to the layer thickness and production rate of each layer.

In the coating liquid for forming each layer, an ultrasonic dispersion machine, a ball mill, a sand mill, a homo mixer, etc. can be used as a means for dispersing particles such as conductive particles and metal oxide particles and charge generating substances. However, it is not limited to these.

The method of applying the coating liquid to form each layer is not particularly limited, but examples include dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular Known methods such as the slide hopper method may be used.

The method for drying the coating film can be appropriately selected depending on the type of solvent and layer thickness, but thermal drying or natural drying is preferable.

The details of the formation process of each layer will be explained below.

<Step (1): Formation of intermediate layer>
For the intermediate layer, prepare a coating solution for forming the intermediate layer by dissolving the binder resin for the intermediate layer in a solvent, and add other components such as conductive particles, metal oxide particles, dispersant, and leveling agent as necessary. After dispersing or dissolving the coating liquid, the coating liquid can be applied to a conductive support to a certain thickness to form a coating film, and the coating film can be dried.

The intermediate layer forming coating liquid is preferably applied using a dip coating method.

The solvent used in the step of forming the intermediate layer is preferably one that can disperse the conductive particles and metal oxide particles well and dissolve the binder resin for the intermediate layer, particularly the polyamide resin. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, tert-butanol, and sec-butanol (2-butanol) improve the solubility of polyamide resin. It has excellent coating performance and is preferred. Further, in order to improve storage stability and particle dispersibility, co-solvents that can be used in combination with the above-mentioned solvents to obtain favorable effects include benzyl alcohol, toluene, dichloromethane, cyclohexanone, and tetrahydrofuran.

<Step (2): Formation of charge generation layer>
The charge generation layer is prepared by dispersing a charge generation substance in a solution in which a binder resin for the charge generation layer is dissolved in a solvent to prepare a coating solution for forming a charge generation layer, and applying the coating solution uniformly over the intermediate layer. It can be formed by coating to a layer thickness of , forming a coating film, and drying the coating film.

The charge generation layer forming coating liquid is preferably applied using a dip coating method.

Examples of the solvent used to form the charge generation layer include toluene, xylene, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, tert-butyl acetate, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, tert-butanol, sec-butanol (2-butanol), methyl cellosolve, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine Examples include, but are not limited to, the following.

<Step (3): Formation of charge transport layer>
For the charge transport layer, a charge transport layer forming coating solution is prepared by dissolving a charge transport layer binder resin and a charge transport substance in a solvent, and the coating solution is applied onto the charge generation layer to a constant layer thickness. It can be formed by forming a coating film and drying the coating film.

The coating liquid for forming the charge transport layer is preferably applied using a dip coating method.

Examples of the solvent used to form the charge transport layer include toluene, xylene, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n- Examples include, but are not limited to, butanol, tert-butanol, sec-butanol (2-butanol), tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like.

<Step (4): Formation of outermost layer>
The outermost layer includes the first polymerizable monomer, the second polymerizable monomer, an inorganic filler treated with a surface modifier, and optionally a polymerization initiator, a specific radical scavenger, a lubricant, and A coating solution for forming the outermost layer is prepared by adding other components such as a charge transport substance to a known solvent, and this coating solution for forming the outermost layer is applied to the outer peripheral surface of the charge transport layer formed in step (3). The coating is applied to form a coating film, this coating is dried, and the polymerizable compound components in the coating are polymerized by irradiation with actinic rays such as ultraviolet rays or electron beams, and the outermost layer is formed by curing. can do.

The coating liquid for forming the outermost layer is preferably applied by a slide hopper method using a circular slide hopper coating device, and can be applied, for example, by a method disclosed in JP-A No. 2015-114454.

As the solvent used to form the outermost layer, any solvent can be used as long as it can dissolve or disperse the polymerizable compound, metal oxide particles, etc. For example, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-propyl alcohol, etc. -Butanol, tert-butanol, sec-butanol (2-butanol), benzyl alcohol, toluene, xylene, dichloromethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3 - Examples include, but are not limited to, dioxolane, pyridine, diethylamine, and the like.

The method of reacting the polymerizable compound is not particularly limited, but examples include a method of reacting by electron beam cleavage, a method of adding a radical polymerization initiator and reacting with light or heat, and the like.

The cured resin component is produced by irradiating the coating film with actinic rays as a curing treatment, generating radicals to polymerize, and forming crosslinking bonds by crosslinking reactions between and within molecules, and then curing. As the active radiation, ultraviolet rays and electron beams are more preferable, and ultraviolet rays are particularly preferable because they are easy to use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without restriction. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, etc. can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is preferably within the range of 5 to 500 mJ/cm ² , more preferably within the range of 5 to 100 mJ/cm ² .

The power of the lamp is preferably in the range of 0.1 to 5 kW, more preferably in the range of 0.5 to 4 kW, even more preferably in the range of 0.5 to 3 kW.

The irradiation time to obtain the required dose of active radiation is preferably 0.1 seconds to 10 minutes, and more preferably 0.1 seconds to 5 minutes from the viewpoint of work efficiency.

In the step of forming the outermost layer, drying can be performed before or after irradiation with active radiation, or during irradiation with active radiation, and the timing of drying can be appropriately selected by combining these.

(Curing equipment and conditions for outermost layer)
In the present invention, the surface hardness in the long axis direction of the photoreceptor can be adjusted by adjusting the light irradiation conditions after coating the outermost layer.

The reason why the surface hardness of the photoconductor can be changed by the light irradiation device is that the surface hardness is correlated with the cumulative amount of light irradiated onto the photoconductor, and the cumulative amount of irradiation is calculated as follows: (cumulative amount of irradiation) = (photoconductor drum) Since it is determined by (amount of irradiation light per unit area of the surface) x (irradiation time per unit area), the surface hardness of the photoreceptor can be changed by changing (i) the amount of irradiation light or (ii) the irradiation time. .

For example, when using the light irradiation device described in JP-A-2013-57787, when pulling up the photoreceptor workpiece from below to above, (i) changing the light irradiation intensity at any position; (ii) By changing the lifting speed of the workpiece, that is, by changing the irradiation time, the cumulative amount of irradiation light on the photoreceptor drum surface can be changed in the long axis direction of the photoreceptor, and the surface hardness of the photoreceptor can be changed. . In particular, the method (ii) of changing the workpiece lifting speed is preferable from the viewpoint of controllability.

《Electrophotographic image forming method》
The electrophotographic image forming method according to the present invention includes at least the following:
1) A charging step of charging the surface of the electrophotographic photoreceptor;
2) an exposure step of forming an electrostatic latent image by exposing the surface of the electrophotographic photoreceptor;
3) a developing step of visualizing the electrostatic latent image with toner to form a toner image;
4) a transfer step of transferring the toner image to a transfer medium;
The electrophotographic photoreceptor used in steps 1) to 4) is preferably the electrophotographic photoreceptor of the present invention.

In addition, if necessary, 5) a cleaning step to remove residual toner;
6) Static elimination process to remove residual charges,
may have.

The electrophotographic photoreceptor (hereinafter also simply referred to as photoreceptor) of the present invention can be used in various known electrophotographic image forming methods. For example, it can be used in a monochrome image forming method or a full color image forming method. Full-color image forming methods include a 4-cycle image forming method consisting of four types of color developing devices for each of yellow, magenta, cyan, and black and one photoreceptor, and a color developing method for each color. Any image forming method can be used, such as a tandem image forming method in which image forming units each having a device and a photoreceptor are mounted for each color.

Specifically, the electrophotographic image forming method according to the present invention includes using the photoconductor of the present invention, charging the photoconductor with a charging device (charging step), and performing imagewise exposure (exposure step). The electrostatic latent image formed is developed using a developing device (developing step) to be visualized and a toner image is obtained. This toner image is transferred onto a transfer medium such as copy paper or a transfer belt (transfer step), and then a static elimination step is performed and the next image forming cycle is performed. The toner image transferred onto a transfer medium such as a transfer belt is transferred onto copy paper, and the toner image transferred onto the copy paper is fixed onto the copy paper by a fixing process such as a contact heating method (fixing process). Obtain a visible image. After the transfer process, the toner remaining on the photoreceptor (transfer residual toner) is removed (cleaning process) using a rubber blade or the like. This cleaning process may be performed before or after the static elimination process, but if the static elimination process is performed by light irradiation, it is better to perform the cleaning process after the cleaning process so that the toner remaining on the photoreceptor absorbs the static elimination light. This is preferable because static electricity can be effectively eliminated without any interference.

In the static neutralization process, either AC static neutralization (AC static neutralization) or optical static neutralization may be used, but AC static neutralization requires the installation of an AC power source, which poses problems such as space issues and the large scale of the equipment. Static elimination is preferable.

《Electrophotographic image forming device》
Next, a specific electrophotographic image forming method will be explained using an electrophotographic image forming apparatus.

In the present invention, an electrophotographic image forming apparatus uses the photoconductor of the present invention, includes a charging means for charging the photoconductor with a charging device, and an exposure device for forming an electrostatic latent image by imagewise exposure. A developing means for developing a toner image by developing it using a developing device, a transfer means for transferring this toner image onto a transfer medium such as paper or a transfer belt, and a static elimination means. . The toner image directly transferred onto the copy paper and the toner image transferred onto the paper via a transfer medium such as a transfer belt are used to obtain a visible image by a fixing means that fixes them to the copy paper through a fixing process such as a contact heating method. After the transfer, the toner remaining on the photoreceptor (transfer residual toner) is removed by a cleaning means such as a cleaning blade.

FIG. 2 is a schematic cross-sectional view showing the structure of a tandem-type electrophotographic image forming apparatus including the electrophotographic photoreceptor of the present invention.

The image forming apparatus 100 shown in FIG. 2 is called a tandem color image forming apparatus, and includes four sets of image forming sections (image forming units) 10Y, 10M, 10C, and 10Bk, an intermediate transfer body unit 7, and a supply unit 7. It consists of a paper means 21 and a fixing means 24. A document image reading device SC is arranged at the top of the main body A of the electrophotographic image forming apparatus.

The four image forming units 10Y, 10M, 10C, and 10Bk rotate around the photoreceptors 1Y, 1M, 1C, and 1Bk, along with charging means 2Y, 2M, 2C, and 2Bk, and exposure means 3Y, 3M, 3C, and 3Bk. From developing means 4Y, 4M, 4C, 4Bk for cleaning, primary transfer rollers 5Y, 5M, 5C, 5Bk as primary transfer means, and cleaning means 6Y, 6M, 6C, 6Bk for cleaning photoreceptors 1Y, 1M, 1C, 1Bk. It is configured.

The electrophotographic image forming apparatus of the present invention uses the photoconductors of the present invention described above as the photoconductors 1Y, 1M, 1C, and 1Bk, respectively.

The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the toner colors provided are different, such as yellow (Y), magenta (M), cyan (C), and black (Bk). It is. Therefore, the image forming unit 10Y will be described in detail below as an example.

The image forming unit 10Y includes a charging means 2Y, an exposing means 3Y, a developing means 4Y, and a cleaning means 6Y around the photoreceptor 1Y, which is an image forming member, and forms a yellow (Y) toner image on the photoreceptor 1Y. It is something that forms.

The charging means 2Y is a means for uniformly charging the surface of the photoreceptor 1Y to negative polarity. As the charging means 2Y, for example, a corona discharge type charger is used.

The exposure means 3Y is a means for exposing the photoreceptor 1Y, which has been given a uniform potential by the charging means 2Y, based on an image signal (yellow) to form an electrostatic latent image corresponding to a yellow image. be. As the exposure means 3Y, one composed of an LED having light emitting elements arranged in an array in the axial direction of the photoreceptor 1Y and an imaging element, a laser optical system, etc. is used.

The developing means 4Y includes, for example, a developing sleeve (not shown) that has a built-in magnet and rotates while holding the developer, a photoreceptor, and a voltage application device that applies a DC and/or AC bias voltage between the developing sleeve and the developing sleeve. It is more than that.

The developing means 4Y includes, for example, a developing sleeve that has a built-in magnet and rotates while holding the developer, and a voltage application device that applies a DC and/or AC bias voltage between the developing sleeve and the photoreceptor. .

The fixing means 24 is, for example, a heat roller fixing device that includes a heating roller equipped with a heat source inside and a pressure roller that is provided in pressure contact with the heating roller so as to form a fixing nip. Examples include methods.

The cleaning means 6Y is composed of a cleaning blade. Note that a brush roller may be provided upstream of this cleaning blade.
Further, a lubricant supply means (not shown) may be provided to supply (apply) a lubricant to the surface of the photoreceptor 1Y. The lubricant supply means can be provided, for example, downstream of the primary transfer roller 5Y and upstream of the cleaning means 6Y. However, it may be on the downstream side of the cleaning means 6Y.

The image forming apparatus 100 is configured by integrally combining components such as a photoreceptor, a developing means, and a cleaning means as a process cartridge (image forming unit), and this image forming unit is detachably attached to the main body of the apparatus. may be configured. Further, at least one of a charging means, an exposure means, a developing means, a transfer means, and a cleaning means are integrally supported together with a photoreceptor to form a process cartridge (image forming unit), and a single image forming unit that can be attached and detached from the main body of the apparatus is formed. It may be constructed as a unit and configured to be detachable using guide means such as rails on the main body of the device.

The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier in the form of a semiconductive endless belt, which is wound around a plurality of rollers and rotatably supported.

Images of each color formed by the image forming units 10Y, 10M, 10C and 10Bk are sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C and 5Bk as primary transfer means. to form a composite color image. The transfer material (image support that carries the fixed final image: for example, plain paper, transparent sheet, etc.) stored in the paper feeding cassette 20 is fed by the paper feeding means 21, and is fed by a plurality of intermediate rollers 22A, 22B, 22C, 22D, and the registration roller 23, it is conveyed to a secondary transfer roller 5b as a secondary transfer means, and is secondarily transferred onto the transfer material P, so that the color image is transferred all at once. The transfer material P on which the color image has been transferred is subjected to a fixing process by the fixing means 24, and is held between paper ejection rollers 25 and placed on a paper ejection tray 26 outside the machine. Here, a transfer support for a toner image formed on a photoreceptor, such as an intermediate transfer member or a transfer material, is collectively referred to as a transfer medium.

On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b serving as the secondary transfer means, the residual toner is removed from the endless belt-shaped intermediate transfer body 70, which is obtained by separating the transfer material P by curvature, by the cleaning means 6b. Ru.

During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C contact the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

The secondary transfer roller 5b comes into contact with the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through it and secondary transfer is performed.

Further, the casing 8 can be pulled out from the apparatus main body A via support rails 82L and 82R.

The housing 8 includes image forming sections 10Y, 10M, 10C, and 10Bk, and an endless belt-shaped intermediate transfer body unit 7.

The image forming units 10Y, 10M, 10C, and 10Bk are arranged in columns in the vertical direction. An endless belt-shaped intermediate transfer unit 7 is arranged on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, and 74, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and cleaning means 6b. Consisting of

《Toner and developer》
In the present invention, "toner base particles" constitute a matrix of "toner particles." The "toner base particles" contain at least a binder resin and a colorant, and may contain other components such as a release agent (wax) and a charge control agent, if necessary. The "toner base particles" are called "toner particles" by adding external additives. The term "toner" refers to an aggregate of "toner particles."

In the present invention, the toner to be applied to the image forming apparatus is not particularly limited, and various known toners can be used.

Although either a pulverized toner or a polymerized toner can be used as the toner, it is preferable to use a polymerized toner from the viewpoint of obtaining a high quality image.

The average particle size of the toner is not particularly limited, but it is preferably within the range of 2 to 8 μm on a volume basis. By setting it as this range, resolution can be made higher.

In addition, appropriate amounts of inorganic particles such as silica and titania with an average particle size of about 10 to 300 nm, abrasives of about 0.2 to 3 μm, etc. are added to the toner base particles as external additives. be able to.

When the toner is used as a two-component developer, conventionally known materials such as ferromagnetic metals such as iron, alloys of ferromagnetic metals and ferromagnetic metals such as aluminum and lead, and compounds of ferromagnetic metals such as ferrite and magnetite can be used as carriers. Magnetic particles consisting of can be used. Among these, ferrite is particularly preferred.

As the carrier, it is preferable to use a carrier further coated with a resin or a so-called resin-dispersed carrier in which magnetic particles are dispersed in the resin. The coating resin composition is not particularly limited, but it is preferable to use, for example, a cyclohexyl methacrylate-methyl methacrylate copolymer.

The volume-based median diameter of the carrier is preferably within the range of 15 to 100 μm, more preferably within the range of 25 to 60 μm.

The concentration of toner contained in the two-component developer is preferably within the range of 4.0 to 8.0% by mass.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In addition, in the following examples, unless otherwise specified, operations were performed at room temperature (25° C.). Further, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

《Preparation of surface-modified inorganic filler》
[Preparation of composite particles C-1 (core-shell particles)]
Composite particles C-1 were prepared by forming a tin oxide shell on the surface of barium sulfate as a core particle using the particle manufacturing apparatus shown in FIG.
Specifically, 3500 mL of pure water was put into the mother liquor tank 111 shown in FIG. 3, and then 900 g of spherical barium sulfate core material with an average particle size _D50 of 100 nm was put in and circulated for 5 cycles. . The flow rate of the slurry flowing out from the mother liquor tank 111 was 2280 mL/min. Further, the stirring speed of the strong dispersion device 113 was set to 16,000 rpm. After the circulation was completed, the slurry was diluted to a total volume of 9000 mL with pure water, and 1600 g of sodium stannate and 2.3 mL of aqueous sodium hydroxide solution (concentration 25 N) were added thereto and circulated for 5 cycles to prepare a mother liquor. . Next, while circulating this mother liquor so that the flow rate S1 flowing out from the mother liquor tank 111 is 200 mL/min, 20 mass% sulfuric acid is added to a "homogenizer magic LAB" (manufactured by IKA Japan Co., Ltd.) serving as a strong dispersion device 113. was supplied. The supply rate S3 was set to 9.2 mL/min. The volume of the homogenizer was 20 cm3, and the stirring speed was 16,000 rpm. Circulation was carried out for 15 minutes, during which time sulfuric acid was continuously fed into the homogenizer. In this way, core-shell type particles were obtained in which a tin oxide coating layer (shell layer) was formed on the surface of the barium sulfate core material. The obtained slurry containing particles was repulped and washed until its conductivity became 600 μS/cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150°C for 10 hours. The obtained dry cake was pulverized, and the pulverized powder was reduced and calcined at 450° C. for 45 minutes in a 1% by volume H ₂ /N ₂ atmosphere. As a result, composite particles C-1 having a number average primary particle size of 100 nm were prepared, in which a tin oxide shell layer was formed on the surface of a barium sulfate core material.
Here, in the particle manufacturing apparatus shown in FIG. 3, reference numerals 112 and 114 are circulation piping for forming a circulation path between the mother liquor tank 111 and the strong dispersion device 113, and numerals 115 and 116 are circulation piping. Pumps provided in the paths 112 and 114, 111a is a stirring blade, 113a is a stirring section, 111b and 113b are shafts, and 111c and 113c are motors.

[Preparation of surface-modified inorganic filler F-1]
Add 20 g of tin oxide (number average primary particle size: 20 nm) as a matrix to 40 mL of methanol, and disperse for 120 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) with the amplitude set to 30 μm. Ta. Next, 1 g of 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM-503) and 40 mL of toluene were added as a surface modifier containing a reactive organic group having a polymerizable group, and the mixture was heated at room temperature for 2 hours. Stir for hours. Next, after removing the solvent with an evaporator, the inorganic filler having a polymerizable group, which has been surface-modified with a reactive organic group-containing surface modifier (KBM-503), is heated at 120°C for 1 hour. Obtained. 10 g of the obtained filler having a polymerizable group was added to 100 mL of 2-butanol, and dispersed for 60 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) at an amplitude of 30 μm. Next, 0.2 g of triethoxysilylethylpolydimethylsiloxyethyl dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-9908) was added as a surface modifier having a silicone chain in the side chain of the silicone main chain, and further Dispersion was carried out for 60 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) with the amplitude set at 30 μm. After dispersion, the solvent is evaporated at room temperature and dried at 80°C for 60 minutes to form a surface modifier that has a polymerizable group derived from a surface modifier containing a reactive organic group and a silicone chain in its side chain. A treated inorganic filler F-1 was prepared.

[Preparation of surface-modified inorganic fillers F-2 to F-9]
In the preparation of the surface-modified inorganic filler F-1, the inorganic filler that was surface-modified was prepared in the same manner except that the compositions of the inorganic filler matrix and the surface modifier were changed as shown in Table I. F-2 to F-9 were prepared. Note that the inorganic filler matrix used in the inorganic filler F-9 was the composite particle C-1 prepared above.

[Preparation of surface-modified inorganic filler F-10]
Add 10 g of tin oxide (number average primary particle size: 20 nm) as a base to 100 mL of 2-butanol, and disperse for 60 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) with the amplitude set to 30 μm. Ta. Next, 0.2 g of triethoxysilylethylpolydimethylsiloxyethyl dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-9908) was added as a surface modifier having a silicone chain in the side chain of the silicone main chain, and further Dispersion was performed for 60 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) with the amplitude set at 30 μm. After dispersion, the solvent was evaporated at room temperature and dried at 80° C. for 60 minutes to prepare inorganic filler F-10 treated with a surface modifier having a silicone chain in its side chain. The surface-modified inorganic filler F-10 was not treated with a surface-modifying agent made of a compound having a polymerizable group.

[Preparation of surface-modified filler F-11]
20 g of tin oxide (number average primary particle size: 20 nm) was added as a matrix to 40 mL of methanol, and dispersed for 120 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) at an amplitude of 30 μm. Next, 1 g of 3-methacryloxypropyltrimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) as a surface modifier containing a reactive organic group having a polymerizable group and 40 mL of toluene were added, and the mixture was heated at room temperature for 2 hours. Stir for hours. After removing the solvent with an evaporator, the mixture was heated at 120° C. for 1 hour to prepare an inorganic filler F-11 having a polymerizable group derived from a surface modifier containing a reactive organic group. The surface-modified inorganic filler F-11 is treated only with a surface modifier containing a reactive organic group having a polymerizable group.

Details of each surface modifier listed by abbreviation in Table I are as follows.
KF-9908: Triethoxysilylethyl polydimethylsiloxyethyl dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd.)
KF-9909: Triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone (manufactured by Shin-Etsu Chemical Co., Ltd.)
KF-99: Linear methyl hydrogen silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.)
KP-574: Surface treatment agent having a silicone chain in the side chain of the acrylic main chain, (acrylates/tridecyl acrylate/triethoxysilylpropyl methacrylate/dimethicone methacrylate) copolymer (manufactured by Shin-Etsu Chemical Co., Ltd.)
KP-578: Graft copolymer consisting of acrylic polymer and dimethylpolysiloxane, in which acrylic polymer is modified with silicone chains (manufactured by Shin-Etsu Chemical Co., Ltd.)
Novec2702: Fluororesin surface treatment agent containing fluorinated methacrylic acid ester polymer (manufactured by 3M Japan)
KBM-503: Silane coupling agent, 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

《Preparation of photoreceptor》
[Preparation of photoreceptor 1]
(1) Preparation of conductive support The surface of a cylindrical aluminum support was cut to prepare a conductive support.

(2) Preparation of Intermediate Layer The following components were mixed and dispersed batchwise for 10 hours using a sand mill as a disperser to prepare a coating solution for forming an intermediate layer. The prepared intermediate layer forming coating solution was applied to the surface of the conductive support prepared above by dip coating, and dried at 110°C for 20 minutes to form an intermediate layer with a thickness of 2 μm on the conductive support. did.
Polyamide resin: X1010 manufactured by Daicel-Evonik 100 parts by mass Titanium oxide particles: SMT500SAS manufactured by Teika 110 parts by mass Titanium oxide particles: SMT150MK manufactured by Teika 160 parts by mass Ethanol 2000 parts by mass

(3) Formation of charge generation layer The following components were mixed, and using a circulating ultrasonic homogenizer (RUS-600TCVP; manufactured by Nippon Seiki Seisakusho Co., Ltd.), the circulating flow rate was 40 L/hour at 19.5 kHz and 600 W. A coating solution for forming a charge generation layer was prepared by dispersing for .5 hours. The charge generation layer forming coating solution prepared above was applied to the surface of the intermediate layer by dip coating and dried to form a charge generation layer having a thickness of 0.3 μm. The charge generating substances described below are titanyl phthalocyanine and ( A mixed crystal of a 1:1 adduct of 2R,3R)-2,3-butanediol and unadducted titanyl phthalocyanine was used.
Charge generating substance 24 parts by mass Polyvinyl butyral resin: S-LEC (registered trademark) BL-1 manufactured by Sekisui Chemical Co., Ltd.)
12 parts by mass Mixed solvent: 3-methyl-2-butanone/cyclohexanone = 4/1 (volume ratio)
1000 parts by mass

(4) Formation of charge transport layer A coating solution for forming a charge transport layer containing the following components is applied onto the surface of the charge generation layer by dip coating, and dried at 120°C for 70 minutes to form a film with a thickness of 24 μm. A charge transport layer was formed.
Charge transport substance 1 (see below) 180 parts by mass Polycarbonate resin: Iupilon Z300 (manufactured by Mitsubishi Gas Chemical Co., Ltd., bisphenol Z type polycarbonate) 300 parts by mass Antioxidant: IRGANOX1010 (manufactured by BASF Corporation) 4 parts by mass Mixed solvent: THF/toluene =4/1 (volume ratio) 2000 parts by mass Silicone oil "KF-96" (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass

(5) Formation of outermost layer The following components were dispersed for 120 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nippon Seiki Seisakusho Co., Ltd.) at an amplitude of 30 μm.
Surface-modified inorganic filler F-1 100 parts by mass 2-butanol 400 parts by mass After preparing the above dispersion by mixing the following first polymerizable monomer and second polymerizable monomer, the following polymerization initiator was added. was stirred and dissolved under light shielding to prepare a coating solution for forming the outermost layer. This coating liquid for forming the outermost layer was applied onto the surface of the charge transport layer using a circular slide hopper coating machine. Next, the applied outermost layer coating film was irradiated with ultraviolet rays (main wavelength: 365 nm) for 1 minute using a metal halide lamp (ultraviolet illuminance: 16 mW/cm ² , cumulative light amount: 960 mJ/cm ² ) to remove the outermost layer coating film. By curing the photoreceptor 1, an outermost layer having a thickness of 5.0 μm was formed on the charge transport layer, thereby producing a photoreceptor 1.
First polymerizable monomer: Exemplary compound M2 50 parts by mass Second polymerizable monomer: HD-N shown below 50 parts by mass Polymerization initiator: IRGACURE819 (manufactured by BASF) 10 parts by mass

[Preparation of photoreceptors 2 to 19]
In the production of the photoreceptor 1, the type of surface-modified inorganic filler used to form the outermost layer and the types and amounts of the first and second polymerizable monomers were changed to the combinations listed in Table II or Table III. Photoreceptors 2 to 19 were produced in the same manner except for that.

[Preparation of photoreceptor 20]
A photoreceptor 20 was prepared in the same manner as the photoreceptor 1 except that the following urethane acrylate monomer UA-1 was used instead of HD-N, which is a polymerizable monomer in the outermost layer.

[Preparation of photoreceptor 21]
A photoreceptor 21 was prepared in the same manner as the photoreceptor 1 except that the surface-modified inorganic filler F-1 was not added to the outermost layer forming coating liquid used to form the outermost layer.

The monomers listed in Table II or Table III below are as follows.

[Measurement of reaction rate]
When the reaction rate was measured using the coating liquid for forming the outermost layer used for photoreceptors 1 to 21 according to the measurement method described below, the values shown in Table II and Table III were obtained.
(Measurement method)
Two PET sheets are prepared by applying the coating liquid for the outermost layer using a wire bar. One sheet is shielded from light to prevent the polymerization reaction from occurring (pre-reaction sample). The other sheet is cured by irradiating it with ultraviolet light (post-reaction sample). The FT-IR spectra of the sample before and after the reaction are measured, and the reaction rate is calculated from the change in the spectrum.
≪Curing conditions≫
Under a nitrogen atmosphere, the PET sheet coated with the surface layer was irradiated with ultraviolet rays (main wavelength: 365 nm) using a metal halide lamp for 1 minute (ultraviolet illuminance: 16 mW/cm ² , cumulative light amount: 960 mJ/cm ² ), and cured. I let it happen.
≪Measurement conditions≫
It can be determined from the peak intensity ratio of a spectrum obtained by total reflection method (ATR method) using a Fourier transform infrared spectrometer (FT-IR; NICOLET380, manufactured by Thermo Fisher Scientific). The ATR measurement was performed using a diamond prism under the conditions of a resolution of 4 cm ⁻¹ and a number of integrations of 32 times.
≪Analysis conditions≫
The intensity of the peak around 2955 cm ^-1 , which is derived from CH (aliphatic) whose structure does not change before and after the reaction, and the peak around 1405 cm ^-1 , which is derived from CH (alkene), whose number decreases due to the reaction, are calculated. The reaction rate [%] was calculated from the following formula.
Formula: 100 - ({After curing Abs (1405 cm ^-1 ) / Abs (2955 cm ^-1 )} / {Before curing Abs (1405 cm ^-1 ) / Abs (2955 cm ^-1 )}) * 100
The peak height of 1405 cm ^-1 (Abs (1405 cm ^-1 )) is 1400 cm ^-1 when the minimum values from 1390 cm ^-1 to 1400 cm -1 and the minimum values between 1410 cm ^{-1 and 1430 cm -1 are} used as base points. It is defined as the maximum value of 1410 cm ⁻¹ from
The peak height of 2955 cm ^-1 ( ^Abs (2955 cm ^-1 )) is 2945 cm -1 when the minimum value of 2560 cm ^-1 to 2590 cm ^-1 and the minimum value of 3135 cm ^-1 and 3165 cm ^-1 are used as base points. It is defined as the maximum value of 2965 cm ⁻¹ from

Details of the monomers listed by abbreviations in Table II and Table III are as follows.
HD-N: 1,6-hexanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)
DCP: Tricyclodecane dimethanol dimethacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)
DOD-N: 1,10-decanediol dimethacrylate (manufactured by Shin Nakamura Chemical Co., Ltd.)
SR454: Ethoxylated (3) trimethylolpropane triacrylate (manufactured by Sartomer)
FA-513M: Dicyclodipentanyl methacrylate (manufactured by Hitachi Chemical)

"evaluation"
[Evaluation of point defects]
(Preparation of image forming device)
Using an image forming apparatus in which a full color printing machine (bizhub PRESS C1070, manufactured by Konica Minolta) was modified to a linear speed of 200 mm/sec, each of the photoreceptors prepared above was placed at the black (Bk) position of the image forming unit. An image forming apparatus for evaluation was manufactured.
(Evaluation of photoreceptor)
In accordance with the method described below, point defects were evaluated for the images formed at the initial stage of printing and after the durability test.
〈Point defects in the initial stage of printing〉
Evaluation of point defects at the initial stage of printing was performed under an environment of 30° C. and 85% RH, using a grid voltage of -800 V on a transfer material: "POD Gloss Coat (A3 size, 100 g/m ² )" (manufactured by Oji Paper Co., Ltd.). A plain image (solid white image) was formed under the condition of a developing bias of -700V, and a printed matter for evaluation of point defects at the initial stage of printing was produced.
<Point defects after durability test>
In the durability test, 500,000 test images consisting of a vertical band solid image with 10% coverage as shown in FIG. 4 were continuously printed in a horizontal feed of A4 paper in an environment of 23° C. and 50% RH.
Next, in the same manner as the initial printing evaluation method described above, a grid was applied on the transfer material: "POD Gloss Coat (A3 size, 100 g/m ² )" (manufactured by Oji Paper Co., Ltd.) in an environment of 30° C. and 85% RH. A plain image (solid white image) was formed under the conditions of a voltage of -800V and a developing bias of -700V, and a printed matter for evaluation of point defects after the durability test was produced.
For each evaluation printed matter created as described above, the number of black spots with a diameter of 0.1 mm or more in a 10 cm x 10 cm area on the transfer material was counted and evaluated according to the following evaluation criteria. Here, ranks A to C were considered to be passed, and ranks D to E were judged to be failed.
A: No sunspots with a diameter of 0.1mm or more are observed in an area of 10cm x 10cm B: 1 to 3 sunspots with a diameter of 0.1mm or more in an area of 10cm x 10cm C: 0.1mm in diameter in an area of 10cm x 10cm D: 10 to 49 sunspots with a diameter of 0.1 mm or more in an area of 10 cm x 10 cm E: 50 or more sunspots with a diameter of 0.1 mm or more in an area of 10 cm x 10 cm

[Evaluation of image blur resistance]
(Preparation of image forming device)
Using an image forming apparatus in which a full color printing machine (bizhub PRESS C1070, manufactured by Konica Minolta) was modified to a linear speed of 500 mm/sec, each of the photoreceptors prepared above was placed at the black (Bk) position of the image forming unit. An image forming apparatus for evaluation was manufactured.
(Evaluation of photoreceptor)
According to the method described below, the image blur resistance was evaluated for the images formed at the initial stage of printing and after the durability test.
<Image blur resistance at the initial stage of printing>
The evaluation of image blur resistance at the initial stage of printing was performed after printing 10,000 sheets of A4 paper with horizontal feed of a test image consisting of a vertically banded solid image with 10% coverage as shown in Figure 4 in an environment of 30°C and 85% RH. Immediately turn off the main power of the image forming apparatus.
Next, after 24 hours after turning off the main power, turn on the main power and become ready to print, immediately coat the entire surface of the A3 size transfer material: "POD Gloss Coat (100 g/m ² )" (manufactured by Oji Paper Co., Ltd.) with a half layer. A tone image (relative reflection density 0.4 using a Macbeth densitometer) was printed to produce a printed matter for evaluation of image blurring resistance at the initial stage of printing.
<Image blur resistance after durability test>
In the durability test, 500,000 test images consisting of a vertical band solid image with 10% coverage as shown in FIG. 4 were continuously printed in a horizontal feed of A4 paper in an environment of 23° C. and 50% RH.
Next, in the same manner as the initial printing evaluation method described above, 10,000 test images consisting of vertical striped solid images with 10% coverage as shown in FIG. Immediately turn off the main power of the image forming apparatus.
Next, after 24 hours after turning off the main power, turn on the main power and become ready to print, immediately coat the entire surface of the A3 size transfer material: "POD Gloss Coat (100 g/m ² )" (manufactured by Oji Paper Co., Ltd.) with a half layer. A tone image (relative reflection density 0.4 using a Macbeth densitometer) was printed to produce a printed matter for evaluation of image blurring resistance after the durability test.
The image quality of the printed halftone image was visually observed for each of the evaluation printed materials produced as described above, and evaluated using the following evaluation criteria. In addition, if density unevenness was observed, the density was measured using a Macbeth densitometer. Here, ranks A to C were considered to be passed, and ranks D to E were judged to be failed.
A: The image is good, with no image blurring B: Band-like density unevenness with a density difference of 0.1 or less with the surrounding area is observed in the long axis direction of the photoreceptor, but there is no density unevenness after printing three halftone images. , there is no practical problem. C: Occurrence of band-like density unevenness with a density difference of 0.1 or less with the surroundings in the long axis direction of the photoconductor is observed, but there is no density unevenness after printing 10 halftone images, and there is no practical problem. No D: Occurrence of band-like density unevenness with a density difference of 0.1 or less with the surroundings in the long axis direction of the photoreceptor was observed, and density unevenness was observed even after printing 10 halftone images, which is a practical problem. E: Band-like density unevenness with a density difference of more than 0.1 from the surrounding area in the long axis direction of the photoreceptor is observed, and density unevenness is observed even after printing 10 halftone images, which is a practical problem.

[Evaluation of scratch resistance]
(Preparation of image forming device)
Using an image forming apparatus in which a full color printing machine (bizhub PRESS C1070, manufactured by Konica Minolta) was modified to a linear speed of 500 mm/sec, each of the photoreceptors prepared above was placed at the black (Bk) position of the image forming unit. An image forming apparatus for evaluation was manufactured.
(Evaluation of photoreceptor)
<An endurance test>
As a durability test, 500,000 sheets of a test image consisting of a vertically banded solid image with 10% coverage shown in FIG. 4 were continuously printed in a horizontal feed of A4 paper in an environment of 23° C. and 50% RH.
Next, in an environment of 23° C. and 50% RH, 200,000 test images consisting of a horizontal band solid image with a coverage of 25% (two horizontal band solid images with a coverage of 12.5%) as shown in Fig. 5 were printed on A4 paper horizontally. Printed continuously. Note that the coverage of the printed portion of this image is 100% in the direction (circumferential direction) perpendicular to the direction of the rotation axis of the photoreceptor.
Next, under an environment of 23° C. and 50% RH, the surface condition of the photoreceptor was visually observed, and the photoreceptor after the durability test was used as an A3 size transfer material: “POD Gloss Coat (100 g/m ² )”. A halftone image (relative reflection density 0.4 using a Macbeth densitometer) was printed on the entire surface of paper (manufactured by Oji Paper Co., Ltd.), and the presence or absence of image defects after the durability test was checked and ranked according to the following criteria. . As the evaluation rank, ranks A to C were regarded as passing, and rank D was regarded as failing.
A: There are no visible scratches on the surface of the photoconductor, and no image defects corresponding to scratches on the photoconductor are observed in the output halftone image, indicating good quality.B: On the surface of the photoconductor Minor scratches are observed in 1 to 3 places by visual inspection, but no image defects corresponding to photoconductor scratches are found in the output halftone image, and there is no practical problem. C: Visual inspection on the photoconductor surface. D: There are 4 to 6 minor scratches on the photoreceptor surface, but no image defects corresponding to the photoreceptor scratches were found in the output halftone image, and there is no problem in practical use.D: Visually observed on the photoreceptor surface. Obvious scratches were observed, and image defects corresponding to the scratches on the photoreceptor were also observed in the output halftone image, which is a practical problem.

As shown in the above results, the photoreceptor of the present invention was found to be able to suppress image blur and point defects over a long period of time, and to have good scratch resistance, compared to the comparative example.

1Y, 1M, 1C, 1Bk Photoreceptor 2Y, 2M, 2C, 2Bk Charging means 3Y, 3M, 3C, 3Bk Exposure means 4Y, 4M, 4C, 4Bk Developing means 5Y, 5M, 5C, 5Bk Primary transfer roller 5b Secondary transfer Rollers 6Y, 6M, 6C, 6Bk, 6b Cleaning means 7 Intermediate transfer unit 8 Housing 10Y, 10M, 10C, 10Bk Image forming unit 20 Paper feed cassette 21 Paper feed means 22A, 22B, 22C, 22D Intermediate roller 23 Registration roller 24 Fixing means 25 Paper discharge roller 26 Paper discharge tray 70 Intermediate transfer body 71, 72, 73, 74 Roller 77 Intermediate transfer body 82L, 82R Support rail 100 Image forming device A Main body SC Original image reading device P Transfer material 101A, 101B Electronic Photographic photoreceptor 102 Conductive support 103 Intermediate layer 104 Photosensitive layer 105 Outermost layer 106 Charge generation layer 107 Charge transport layer 110 Conductive particle manufacturing device 111 Mother liquor tank 111a Stirring blade 111b First shaft 111c First motor 112 First piping 113 Strong dispersion device 113a Stirring section 113b Second shaft 113c Second motor 114 Second piping 115 First pump 116 Second pump

Claims (10)

An electrophotographic photoreceptor having a curable outermost layer,
The outermost layer includes at least a first polymerizable monomer having three or four polymerizable groups in one monomer molecule, and a second polymerizable monomer having two polymerizable groups in one monomer molecule, A polymerizable cured product containing an inorganic filler treated with a surface modifier, and
An electrophotographic photoreceptor, wherein the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via a hydrocarbon. The electrophotographic photoreceptor according to claim 1, wherein the surface modifier has a silicone chain. 3. The electrophotographic photoreceptor according to claim 1, wherein the inorganic filler treated with the surface modifier has a polymerizable group. 4. The electrophotographic photoreceptor according to claim 1, wherein the surface modifier has a silicone chain in a side chain. 5. The electrophotographic photoreceptor according to claim 4, wherein the surface modifier having a silicone chain in its side chain has a silicone side chain branched from an acrylic main chain. 5. The electrophotographic photoreceptor according to claim 4, wherein the surface modifier having a silicone chain in its side chain has a silicone side chain branched from a silicone main chain. The electrophotography according to any one of claims 1 to 6 , wherein the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via an alkylene group. Photoreceptor. The electronic polymer according to any one of claims 1 to 7 , wherein the content of the second polymerizable monomer is within a range of 30 to 70% by mass based on the total monomers. Photographic photoreceptor. An electrophotographic photoreceptor having a curable outermost layer,
The outermost layer comprises at least a first polymerizable monomer having three or more polymerizable groups in one monomer molecule, a second polymerizable monomer having two polymerizable groups in one monomer molecule, and surface modification. A polymerizable cured product containing an inorganic filler treated with an agent, and
An electrophotographic photoreceptor, wherein the second polymerizable monomer has a structure in which two of the polymerizable groups are bonded via an alkylene group. An electrophotographic image forming apparatus comprising the electrophotographic photoreceptor according to any one of claims 1 to 9.

Images