JP5560930B2 - Image forming apparatus and process cartridge - Google Patents

Description

  The present invention has high abrasion resistance and excellent toner releasability, and an abnormal image due to adhesion of the silica contained in a specific toner component (toner in which silica fine particles are attached to the surface of toner base particles). Image forming apparatus and process capable of realizing stable and high-quality image formation over a long period of time with excellent durability by using an electrophotographic photosensitive member capable of suppressing the occurrence of toner for a long period of time and a specific toner It relates to the cartridge.

  Conventionally, organic photoreceptors (OPCs) have been widely used for copying machines, facsimile machines, laser printers, and their combined machines in place of inorganic photoreceptors because of various advantages. This is because, for example, (1) optical characteristics such as the light absorption wavelength range and the amount of absorption, (2) electrical characteristics such as high sensitivity and stable charging characteristics, and (3) material selection range (4) Ease of manufacturing, (5) Low cost, (6) Non-toxicity, and the like.

  Recently, the diameter of the photoconductor has been reduced due to the downsizing of the image forming apparatus, and the high speed of the machine and the maintenance-free movement have been added to increase the durability of the photoconductor. From this point of view, organic photoreceptors are generally soft because the surface layer is mainly composed of low molecular charge transport materials and inert polymers, and when used repeatedly in an electrophotographic process, the organic photoreceptors depend on development systems and cleaning systems. There is a drawback that wear is likely to occur due to a mechanical load. In addition, due to the demand for higher image quality, the cleaning blade is required to increase its rubber hardness and contact pressure for the purpose of improving the cleaning property as the particle size of the toner particles is reduced. This also promotes the wear of the photoreceptor. It is a factor. Such wear of the photoreceptor deteriorates electrical characteristics such as sensitivity deterioration and chargeability, and causes abnormal images such as image density reduction and background stains. Further, scratches where wear is locally generated cause streak-like stain images due to poor cleaning.

  Therefore, in order to increase the durability of the organic photoreceptor, it is indispensable to reduce the amount of wear, but it is also required to increase the toner releasability as a means for improving the cleaning property. In particular, when the silica contained in the toner component adheres to the photoreceptor due to a decrease in the amount of wear, it is very difficult to remove the adhered silica. It has a problem that the toner component gradually adheres to the photoconductor, leading to the occurrence of abnormal images in which the adhering matter appears in the image, and has a good surface property that combines wear resistance and high releasability. There is a need for an organic photoreceptor.

  For example, (1) a surface protection layer containing an organic silane compound and polyvinyl butyral (see Patent Document 1), (1) 2) Surface protective layer containing siloxane resin and polyvinyl butyral (see Patent Document 2), (3) Antioxidant having a chain-curing functional group and silicon atom in the surface protective layer, anti-degradation agent, light shielding (4) A copolymer containing polyorganosiloxane as a constituent component is dispersed in the surface layer, and the surface layer has at least a charge transporting property. Using a cross-linked resin layer obtained by curing a tri- or higher functional radical polymerizable monomer having no structure and a monofunctional radical polymerizable compound having a charge transporting structure (see Patent Document 4) (5) Containing 10% by weight or more of fluororesin fine particles so that the contact angle with the pure water on the outermost layer surface of the photoreceptor is 100 ° or more (see Patent Document 5), (6) The circumference of the electrophotographic photoreceptor A method of obtaining high cleaning performance by having a plurality of dimple-shaped concave portions on the surface (see Patent Document 6), (7) polyester resin in which the photosensitive layer has a specific structural unit, and carboxylic acid and alcohol are ester-bonded And those containing a wax having 20 to 150 carbon atoms (Patent Document 7). However, none of these has fully satisfied the durability required to maintain the electrical and mechanical durability and high releasability required for the organic photoreceptor for a long period of time.

  In view of the above, even in the prior art documents, it cannot be said that the organic photoreceptor having a satisfactory surface property still has a satisfactory overall characteristic.

An object of the present invention is to solve various problems in the prior art and achieve the following objects.
That is, the present invention has high wear resistance and excellent toner releasability. In particular, abnormalities due to adhesion of silica contained in toner components formed by attaching silica fine particles hydrophobized to the surface of toner base particles. By using an electrophotographic photosensitive member having a surface protective layer capable of suppressing the occurrence of images and the like over a long period of time, an image forming apparatus capable of realizing stable and high-quality image formation for a long period of time with excellent durability, and An object is to provide a process cartridge.

As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, a reaction product of a tri- or higher functional radical polymerizable monomer and a radical polymerizable compound having a charge transporting structure (hereinafter referred to as “cured product”). And an electrophotographic photosensitive member having a specific surface protective layer containing a polyvinyl acetal compound synthesized by acetalization reaction between polyvinyl alcohol and an aldehyde is provided and formed on the surface of the electrophotographic photosensitive member. The image forming apparatus includes a developing unit that develops the electrostatic latent image using toner in which silica fine particles hydrophobized to the surface of toner base particles containing at least a binder resin and a colorant are attached. It has been found that the above problem can be effectively achieved by the configuration.
This invention is based on the said knowledge by the present inventors, and the said subject is solved by the invention described in the following [1]-[ 5 ]. Hereinafter, the present invention will be specifically described.

[1]: The above problems include an electrophotographic photosensitive member, a charging unit for charging the surface of the electrophotographic photosensitive member, an exposure unit for exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image, Developing means for developing the electrostatic latent image using a toner in which silica fine particles hydrophobized to the surface of toner base particles containing at least a binder resin and a colorant are attached to form a visible image; An image forming apparatus comprising: a transfer unit that transfers the visible image to a recording medium; and a fixing unit that fixes the transfer image transferred to the recording medium.
The electrophotographic photoreceptor comprises at least a photosensitive layer and a surface protective layer on a support, and the surface protective layer comprises a radical polymerizable monomer having a trifunctional or higher functional group and a radical polymerizable compound having a charge transporting structure. A polyvinyl acetal compound synthesized by a reaction product and an acetalization reaction between polyvinyl alcohol and an aldehyde is contained . The polyvinyl acetal compound is represented by the following general formula (I), and the number average molecular weight of the polyvinyl acetal compound is 100,000. This is solved by the image forming apparatus characterized in that the composition ratio n of the repeating unit containing a hydroxyl group is 25 mol% or more .

[In formula (I), R ₁ and R ₂ represent different alkyl groups having 1 to 3 carbon atoms. k, l, m, n represents a composition ratio (mol%), and one of k or l may be 0, but the sum of k and l, m and n both have a value greater than 0. The sum of k, l, m, and n is 100. ]

[ 2 ]: In the image forming apparatus described in [1] above, the polyvinyl acetal compound has a glass transition temperature of 70 ° C. or higher.

[ 3 ]: In the image forming apparatus according to [1] or [2] , the content of the polyvinyl acetal compound is 5 to 100 parts by mass with respect to 100 parts by mass of the trifunctional or higher functional radical polymerizable monomer. It is characterized by being.

[ 4 ]: In the image forming apparatus according to any one of [1] to [ 3 ], a primary average particle diameter of the hydrophobized silica fine particles is 100 to 200 nm.

[ 5 ]: The above-mentioned problem includes at least an electrophotographic photosensitive member and at least one means selected from a charging means, a developing means, a transfer means, a cleaning means, and a charge eliminating means, and [1] to [ 4 ] This is solved by a process cartridge which is detachable from the main body of the image forming apparatus described in any one of the above.

  According to the present invention, a reaction product (cured product) of a radical polymerizable monomer having three or more functional groups and a radical polymerizable compound having a charge transport structure, and a polyvinyl acetal compound synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde By using an electrophotographic photosensitive member having a surface protective layer containing a toner, it exhibits excellent wear resistance and toner releasability, and silica toner particles hydrophobized on the surface of the toner base particles. Even when toner is used, it is possible to suppress the occurrence of abnormal images due to the adhesion of silica over a long period of time, thereby realizing stable and high-quality image formation over a long period of time with excellent durability. An image forming apparatus and a process cartridge that can be provided can be provided.

2 is a schematic cross-sectional view showing an example of a layer structure of an electrophotographic photosensitive member in the image forming apparatus of the present invention. FIG. It is a schematic sectional drawing which shows another layer structural example of the electrophotographic photoreceptor in the image forming apparatus of this invention. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. It is the schematic which shows an example of the process cartridge of this invention.

An image forming apparatus according to the present invention includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that exposes the charged electrophotographic photosensitive member surface to form an electrostatic latent image, Developing means for developing the electrostatic latent image using a toner in which silica fine particles hydrophobized to the surface of toner base particles containing at least a binder resin and a colorant are attached to form a visible image; An image forming apparatus comprising: a transfer unit that transfers the visible image to a recording medium; and a fixing unit that fixes the transfer image transferred to the recording medium.
The electrophotographic photoreceptor comprises at least a photosensitive layer and a surface protective layer on a support, and the surface protective layer comprises a radical polymerizable monomer having a trifunctional or higher functional group and a radical polymerizable compound having a charge transporting structure. It contains a reaction product (cured product) and a polyvinyl acetal compound synthesized by acetalization reaction between polyvinyl alcohol and an aldehyde.
Here, the polyvinyl acetal compound is preferably represented by the following general formula (I).

[In formula (I), R ₁ and R ₂ represent different alkyl groups having 1 to 3 carbon atoms. k, l, m, n represents a composition ratio (mol%), and one of k or l may be 0, but the sum of k and l, m and n both have a value greater than 0. The sum of k, l, m, and n is 100. ]

  That is, the image forming apparatus of the present invention contains at least a binder resin and a colorant as toner for developing a latent image formed on the surface of an electrophotographic photosensitive member by a developing unit to form a visible image. The surface protective layer of the electrophotographic photosensitive member provided in the image forming apparatus is a radical having at least trifunctional or higher functionality. It contains a reaction product (cured product) of a polymerizable monomer and a radical polymerizable compound having a charge transporting structure, and a polyvinyl acetal compound synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde. With such a configuration, high wear resistance and high release properties can be obtained, and even when the toner is used, the occurrence of abnormal images due to silica adhesion can be suppressed over a long period of time. As a polyvinyl acetal compound, what is represented by the said general formula (I) is used preferably, and it turned out that high mold release property is obtained over this by this.

In particular, by using the polyvinyl acetal compound (resin) having a glass transition temperature of 70 ° C. or higher, the resin exhibits a low viscosity, so that a more excellent release effect can be obtained. Moreover, it is desirable to use a polyvinyl acetal compound having a number average molecular weight of 100,000 or more and a composition ratio n of a repeating unit containing a hydroxyl group of 25 mol% or more. That is, since the compound has many hydroxyl groups, the polarity is high, and the adhesion reduction effect of hydrophobic silica is estimated to be very high.
When the polyvinyl acetal compound is used, it exhibits excellent releasability with respect to a toner in which silica fine particles hydrophobized on the surface of toner base particles containing at least a binder resin and a colorant are attached, It is possible to obtain an excellent effect of suppressing the occurrence of an abnormal image caused by the silica detached from the toner adhering to the surface protective layer.
The reason is not clear, but it is estimated that the following effects can be obtained.

That is, the hydrophobized silica fine particles (hydrophobic silica) contained in the toner components used for developing the electrostatic latent image in the present invention are effective for the fluidity and charging characteristics of the toner. Although it plays a role, since the amount of hydroxyl groups on the surface of hydrophobic silica is small and the carbon component is relatively increased, the polarity of silica is small (low polarity).
Therefore, for example, in the case of a commonly used photoreceptor (the surface of the photoreceptor has a small polarity and has properties similar to hydrophobic silica), it is considered that hydrophobic silica is likely to adhere to the surface of the photoreceptor. .
On the other hand, the polyvinyl acetal compound contained in the surface protective layer of the electrophotographic photosensitive member used in the present invention has a high polarity because it contains many hydroxyl groups in the compound. Therefore, the adhesion force between the surface protective layer and the low-polarity hydrophobic silica is reduced, and it is considered that the hydrophobic silica is less likely to adhere to the surface of the photoreceptor in the image forming apparatus of the present invention.

As described above, the surface protective layer of the electrophotographic photosensitive member provided in the image forming apparatus of the present invention is a reaction product (curing) of a radical polymerizable monomer having a trifunctional or higher functionality and a radical polymerizable compound having a charge transporting structure. Product) and a polyvinyl acetal compound synthesized by acetalization reaction between polyvinyl alcohol and an aldehyde.
By using a tri- or higher functional radical polymerizable monomer, a surface protective layer having a high crosslinking density is obtained by the development of a three-dimensional network structure by a curing reaction with a radical polymerizable compound having a charge transporting structure, High wear resistance is achieved, and at the same time, the composition is cured in a short time to form a hardened cross-linked bond, thereby improving durability. Furthermore, since a radically polymerizable compound having a charge transporting structure is incorporated in the surface protective layer, stable electrical characteristics can be obtained over a long period of time. Furthermore, since it is excellent in compatibility with the polyvinyl acetal compound, it becomes possible to uniformly distribute the hydroxyl groups in the polyvinyl acetal compound in the network structure. became.
For example, when a low molecular charge transport material having no functional group is included in the surface protective layer, precipitation of the low molecular charge transport material or white turbidity occurs due to its low compatibility. The mechanical strength of the protective layer also decreases, and sensitivity is lowered due to charge trapping, and residual potential is increased.

  Conventionally, when a bifunctional or higher functional charge transporting compound is used together with a trifunctional or higher radical polymerizable monomer as a surface protective layer of an electrophotographic photoreceptor, the charge transporting structure is very bulky. The internal stress of the protective layer is increased, distortion occurs in the cured resin, and cracks and scratches frequently occur. However, when the polyvinyl acetal compound in the present invention is contained, the polyvinyl acetal resin present in the surface protective layer can relieve internal stress and suppress the generation of cracks and scratches.

Therefore, a surface protective layer comprising a reaction product (cured product) of a radical polymerizable monomer having three or more functional groups and a radical polymerizable compound having a charge transporting structure in the present invention, and a polyvinyl acetal compound is provided. An image forming apparatus in which an electrophotographic photosensitive member is provided and developed using toner in which silica fine particles hydrophobized to the surface of toner base particles containing at least a binder resin and a colorant are attached by a developing unit. Accordingly, it is possible to realize an image forming apparatus that maintains high releasability over a long period of time and can stably output excellent image quality.
Hereinafter, the electrophotographic photosensitive member will be described in detail.

(Electrophotographic photoreceptor)
The electrophotographic photoreceptor of the present invention comprises at least a photosensitive layer and a surface protective layer on a support, and further comprises other layers as necessary.
<Surface protective layer>
As described above, the surface protective layer contains a reaction product (cured product) of a tri- or higher functional radical polymerizable monomer and a radical polymerizable compound having a charge transporting structure, and a polyvinyl acetal compound. A polyvinyl acetal compound is a resin obtained by acetalization reaction of polyvinyl alcohol and an aldehyde, that is, acetalization of polyvinyl alcohol (PVA; polyvinyl alcohol resin) with an aldehyde.

   Although it does not specifically limit as said polyvinyl acetal compound, The polyvinyl formal resin obtained by making polyvinyl alcohol resin and formaldehyde react, The polyvinyl acetoacetal resin obtained by making polyvinyl alcohol resin and acetaldehyde react (Polyvinyl acetal resin in a narrow sense) ), Polyvinyl butyral resin obtained by reacting polyvinyl alcohol resin and n-butyraldehyde. These polyvinyl acetal compounds may be used independently and 2 or more types may be used together.

  It does not specifically limit as a manufacturing method of a polyvinyl acetal compound. As an example, a polyvinyl alcohol resin is dissolved in warm water or hot water, and the resulting aqueous solution is maintained at a predetermined temperature of about 0 to 95 ° C., and an aldehyde and an acid catalyst are added and acetalized while stirring. To advance. Next, the reaction is completed by raising the reaction temperature and aging. Thereafter, various steps of neutralization, washing with water and drying are performed. In this way, a powdery polyvinyl acetal resin can be obtained.

Moreover, the more excellent effect is acquired by using the thing whose glass transition temperature of a polyvinyl acetal compound is 70 degreeC or more especially among the said polyvinyl acetal compounds.
As a method for obtaining a polyvinyl acetal compound having a glass transition temperature of 70 ° C. or higher, the glass transition temperature is greatly different depending on the amount of acetyl groups, and the glass transition temperature can be increased by reducing the amount of acetyl groups.
The glass transition temperature can be determined by a differential scanning calorimetry (DSC) method described in JIS K 7121.

  These polyvinyl acetal compounds can be obtained by the above production method, but commercially available products can also be used. Commercially available products include, for example, ESREC BX-L, ESREC BH-3, ESREC BX-1, ESREC BX-5, ESREC KS-10, ESREC KS-1, ESREC KS-3, and ESREC KS-5 (all Sekisui Chemical Industry), Denkabuchiral # 5000-A, Denkabuchiral # 5000-D, Denkabuchiral # 6000-C, Denkabuchiral # 6000-EP, Denkabuchiral # 6000-CS, Denkabuchiral # 6000-AS (all Manufactured by Denki Kagaku Kogyo Co., Ltd.).

As described above, it is more preferable to use one having a glass transition temperature of 70 ° C. or higher, and further having a number average molecular weight of 100,000 or higher and a composition ratio n of a repeating unit containing a hydroxyl group of 25 mol% or higher. However, such molecular weight and hydroxyl group amount can be adjusted by the polyvinyl alcohol resin used and the acetalization reaction.
In addition, the molecular weight of a polyvinyl acetal compound can be calculated | required as a calculated molecular weight based on the polymerization degree of the polyvinyl alcohol resin used for reaction.
The amount of hydroxyl groups can be determined by evaluating the degree of acetalization by ¹³ C-NMR evaluation because the polyvinyl acetal resin is obtained by acetalizing the polyvinyl alcohol resin.

  It does not specifically limit as an aldehyde used for the said acetalization reaction, For example, a C1-C10 aldehyde etc. are mentioned. More specifically, for example, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, formaldehyde, acetaldehyde And benzaldehyde. These aldehydes may be used alone or in combination of two or more. Of these, n-butyraldehyde, n-hexyl aldehyde, n-valeraldehyde and the like are preferable, and butyraldehyde having 4 carbon atoms is more preferable.

  The content of the polyvinyl acetal compound in the surface protective layer is preferably 5 to 100 parts by mass with respect to 100 parts by mass of the tri- or higher functional radical polymerizable monomer from the viewpoint of the balance between wear resistance and high releasability. If the content of the polyvinyl acetal compound is less than 5 parts by mass, the releasability is reduced, and if it exceeds 100 parts by mass, the wear resistance is reduced and the life is reduced.

<Trifunctional or higher radical polymerizable monomer>
The trifunctional or higher functional radical polymerizable monomer used in the present invention includes, for example, hole transport structures such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group and nitro group. A monomer that does not have an electron transport structure such as an electron-withdrawing aromatic ring and has three or more radically polymerizable functional groups.
The radical polymerizable functional group may be any group having a carbon-carbon double bond and capable of radical polymerization.
Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

  (1) As 1-substituted ethylene functional group, the functional group represented by the following general formula (a) is mentioned, for example.

[In the formula (a), X ₁ represents an arylene group which may have a substituent, an alkenylene group which may have a substituent, a —CO— group, a —COO— group, a —CON ( R < ₁₀ >)-group [R < ₁₀ > represents a hydrogen atom, an alkyl group, an aralkyl group, and an aryl group. Or an S-group. ]

  Examples of the arylene group which may have a substituent of the above formula (a) include a phenylene group and a naphthylene group which may have a substituent, and examples of the alkyl group include a methyl group and an ethyl group. However, examples of the aralkyl group include a benzyl group, a naphthylmethyl group, and a phenethyl group, and examples of the aryl group include a phenyl group and a naphthyl group.

  Specific examples of the group represented by the general formula (a) include vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyloxy group, acryloylamide group, vinylthioether group. , Etc.

  (2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following general formula (b).

[In the formula (b), Y represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a halogen atom. , A cyano group, a nitro group, an optionally substituted alkoxy group, a —COOR ₇₉ group [R ₇₉ has a hydrogen atom, an optionally substituted alkyl group, or a substituent. May be an aralkyl group, an aryl group which may have a substituent, or —CONR ₈₀ R ₈₁ (R ₈₀ and R ₈₁ have a hydrogen atom, an alkyl group which may have a substituent, or a substituent. An aralkyl group which may be substituted, or an aryl group which may have a substituent, which may be the same or different from each other. ] Is represented. X ₂ represents the same substituent, single bond, and alkylene group as X _{1 in the} formula (a). However, Y, at least one oxycarbonyl group in X _2, a cyano group, an alkenylene group, and an aromatic ring. ]

  Examples of the aryl group which may have a substituent of the general formula (b) include a phenyl group which may have a substituent, a naphthyl group, etc., and an alkoxy group which may have a substituent. A methoxy group or an ethoxy group that may have a substituent, and an alkyl group that may have a substituent include a methyl group that may have a substituent, an ethyl group, and the like. Examples of the aralkyl group that may have include benzyl, naphthylmethyl, or phenethyl which may have a substituent.

  Specific examples of the group represented by the general formula (b) include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group. Groups and the like.

In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as a methyl group, an ethyl group, a methoxy group, and an ethoxy group And aryloxy groups such as phenoxy group, aryl groups such as phenyl group and naphthyl group, and aralkyl groups such as benzyl group and phenethyl group.

  Among these radical polymerizable functional groups, an acryloyloxy group and a methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule. It can be obtained by an ester reaction or a transesterification reaction using acrylic acid (salt), acrylic acid halide, and acrylic ester. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

The trifunctional or higher functional radical polymerizable compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA-modified trimethylolpropane. Triacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, HPA-modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol tri Acrylate, ECH modified glycerol triacrylate, EO modified glycerol triacrylate, PO modified Lyserol triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol Tetraacrylate, alkyl-modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO-modified phosphate triacrylate, 2,2,5,5, -tetrahydroxymethylcyclopentanone tetraacrylate , Etc. These may be used individually by 1 type and may use 2 or more types together.
In the above, HPA modification refers to hydroxypropyl acrylate modification, ECH modification refers to epichlorohydrin modification, EO modification refers to ethyleneoxy modification, and PO modification refers to propyleneoxy modification.

  The content of the tri- or higher functional radical polymerizable compound is preferably 30 parts by mass to 70 parts by mass in the total amount of the surface protective layer (100 parts by mass) from the viewpoint of wear resistance and electrical characteristics. When the content is less than 30 parts by mass, the wear resistance decreases, and when it exceeds 70 parts by mass, the charge transport property decreases.

  The surface protective layer contains at least a trifunctional or higher functional radical polymerizable monomer, a reaction product (cured product) of a radical polymerizable compound having a charge transporting structure, and a polyvinyl acetal compound. For the purpose of imparting further functions, a radical polymerizable monomer, a functional monomer, and a radical polymerizable oligomer can be used in combination.

  There is no restriction | limiting in particular as said radically polymerizable monomer, According to the objective, it can select suitably, For example, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2- Ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, styrene monomer, 1, 3-butanediol diacrylate, 1,4-butanediol diacrylate, , 4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate Examples thereof include acrylate and neopentyl glycol diacrylate.

  There is no restriction | limiting in particular as said functional monomer, According to the objective, it can select suitably, For example, octafluoropentyl acrylate, 2-perfluoro octyl ethyl acrylate, 2-perfluoro octyl ethyl methacrylate, 2-perfluoro Reactive additives having a fluorine atom substituted such as isononylethyl acrylate or radical polymerizable functional groups, for example, reactive silicone additives such as PO-modified-2-neopentyl glycol diacrylate are also used effectively it can. These functional monomers may be used alone or in combination of two or more.

  The content of the radical polymerizable monomer and the functional monomer is preferably 0.01 to 30 parts by mass in the coating liquid solid content (100 parts by mass) forming the surface protective layer, and 0.05 parts by mass to 20 parts by mass is more preferable.

The radical polymerizable oligomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include urethane acrylate oligomers and polyester acrylate oligomers.
However, when a large amount of monofunctional and bifunctional radically polymerizable monomers, functional monomers, and radically polymerizable oligomers are contained, the three-dimensional cross-linking density of the surface protective layer is substantially reduced, resulting in a decrease in wear resistance. There is a fear. For this reason, 100 parts by mass or less is preferable with respect to 100 parts by mass of the tri- or higher functional radical polymerizable compound used in the present invention.

<Radically polymerizable compound with charge transport structure>
The radical polymerizable compound having a charge transporting structure means a compound having a hole transporting structure or an electron transporting structure and having a radical polymerizable functional group.
Examples of the hole transporting structure include triarylamine, hydrazone, pyrazoline, carbazole, and the like.
Examples of the electron transporting structure include condensed polycyclic quinone, diphenoquinone, cyano group, nitro group, and the like.
The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization, and the radical functional group is preferably monofunctional or bifunctional.

  The charge transporting compound having a radical polymerizable functional group is polymerized by opening a carbon-carbon double bond on both sides, so that it does not become a terminal structure but is incorporated into a chain polymer to form a crosslink. In the polymer, it exists in the main chain of the polymer and in the cross-linked chain between the main chain and the main chain (this cross-linked chain includes an intermolecular cross-linked chain between one polymer and another polymer). And a part of the main chain folded in one polymer and an intramolecular cross-linked chain in which the other part derived from the polymerized monomer is cross-linked in the main chain at a position away from it) May be present in the main chain or in the cross-linked chain.

As the charge transporting compound having a radical polymerizable functional group, a radical polymerizable monomer having a charge transporting structure having a triarylamine structure is preferably used. Here, as the radical polymerizable group, those having an acryloyl group or a methacryloyl group are preferable.
A radically polymerizable monomer having a charge transporting structure having a triarylamine structure has at least three aryl groups arranged in a radial direction from a nitrogen atom suspended from the chain part, and is a bulky, but directly bonded to the chain part Since it is suspended from the chain portion via a carbonyl group or the like, it is fixed in a state that is flexible in three-dimensional positioning. Since these triarylamine structures can be arranged spatially adjacent to each other in the polymer, there is little structural distortion in the molecule, and when it is used as a protective layer of an electrophotographic photosensitive member, It is speculated that it can have an intramolecular structure that is relatively free from disruption.
Specific examples (No. 1 to No. 38) of charge transporting compounds having a radical polymerizable functional group having a triarylamine structure as a charge transporting structure are shown below, but are limited to compounds having these structures. is not.

The radical polymerizable compound having the charge transporting structure is important for imparting charge transporting performance to the surface protective layer, and the content of the radical polymerizable compound having the charge transporting structure is the total amount of the surface protective layer ( 100 parts by mass), 20 parts by mass to 80 parts by mass are preferable, and 30 parts by mass to 70 parts by mass are more preferable. When the content is less than 20 parts by mass, the charge transport performance of the surface protective layer cannot be sufficiently maintained, and deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential may appear due to repeated use. If it exceeds the mass part, the crosslink density of the surface protective layer is lowered and the releasability is reduced, and high wear resistance and releasability are not exhibited. Although the electrical characteristics and abrasion resistance required differ depending on the process used, it cannot be said unconditionally, but the range of 30 parts by mass to 70 parts by mass is most preferable in consideration of the balance of both characteristics.
Examples of the synthesis of radically polymerizable compounds having a charge transporting structure are illustrated below.

<Synthesis Example of Radical Polymerizable Compound Having Charge Transporting Structure>
The compound having the charge transporting structure in the present invention is synthesized based on, for example, the method described in Japanese Patent No. 3164426.
(1) Synthesis of hydroxy group-substituted triarylamine compound [the following structural formula (B)] 113.85 g (0.3 mol) of a methoxy group-substituted triarylamine compound [the following structural formula (A)] and 138 g of sodium iodide ( 0.92 mol) was added 240 ml of sulfolane and heated to 60 ° C. in a nitrogen stream. In this solution, 99 g (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour and stirred at a temperature of about 60 ° C. for 4 and a half hours to complete the reaction. About 1.5 L of toluene was added to the reaction solution, cooled to room temperature, and repeatedly washed with water and an aqueous sodium carbonate solution. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (silica gel as the adsorption medium and toluene: ethyl acetate = 20: 1 as the developing solvent).
Cyclohexane was added to the obtained pale yellow oil to precipitate crystals. In this way, 88.1 g (yield = 80.4%) of white crystals of the following structural formula (B) was obtained. The melting point is 64.0-66.0 ° C.

  The elemental analysis values (unit:%) of the white crystals represented by the structural formula (B) obtained above are shown in Table 1 below together with the calculated values.

(2) Triarylamino group-substituted acrylate compound (Exemplary Compound No. 7)
82.9 g (0.227 mol) of the hydroxy group-substituted triarylamine compound obtained in (1) above [the structural formula (B)] is dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12) in a nitrogen stream. 0.4 g, water: 100 ml) was added dropwise. The solution was cooled to 5 ° C., and 25.2 g (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was complete | finished. The reaction solution was poured into water and extracted with toluene. This extract was repeatedly washed with an aqueous sodium bicarbonate solution and water. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals. Thus, 80.73 g (yield = 84.8%) of white crystals of (Exemplary Compound No. 7) was obtained. The melting point is 117.5-119.0 ° C.
The elemental analysis values (unit:%) of the obtained triarylamino group-substituted acrylate compound (Exemplary Compound No. 7) are shown in Table 2 below together with the calculated values.

<Polymerization initiator>
The surface protective layer contains at least a reaction product (cured product) of a tri- or higher functional radical polymerizable monomer, a radical polymerizable compound having a charge transporting structure, and a polyvinyl acetal compound. A polymerization initiator may be used in order to efficiently advance the curing reaction between the functional polymerizable or higher radical polymerizable monomer and the radical polymerizable compound having a charge transporting structure.
Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator, and a photopolymerization initiator is preferable from the viewpoint of polymerization efficiency.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5. -Peroxide-based initiators such as di (peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide; azobisisobutylnitrile, azobis Examples thereof include cyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, and azo initiators such as 4,4′-azobis-4-cyanovaleric acid. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 4- (2-hydroxyethoxy) phenyl. -(2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2-hydroxy-2-methyl-1-phenylpropan-1-one Acetophenone-based or ketal-based photopolymerization of 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Agents: benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobuty Benzoin ether photopolymerization initiators such as ether and benzoin isopropyl ether; benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1 Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene; thioxanthone photopolymerization such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Initiators; and the like.

  Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine compound, imidazole compound, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together.

In addition, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples thereof include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.
The content of the polymerization initiator is preferably 0.5 parts by mass to 40 parts by mass, and more preferably 1 part by mass to 20 parts by mass with respect to 100 parts by mass of the total content having radical polymerizability.

<Filler>
The surface protective layer includes at least a reaction product (cured product) of a radical polymerizable monomer having a trifunctional or higher functionality and a radical polymerizable compound having a charge transport structure, and polyvinyl synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde. Although it contains an acetal compound, in addition to these components, it is preferable to contain a filler for the purpose of improving wear resistance.

As the filler, either an organic filler or an inorganic filler is used.
Examples of the organic filler include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, and a-carbon powder.
Examples of the inorganic filler include metal powders such as copper, tin, aluminum, and indium; silica, tin oxide, zinc oxide, titanium oxide, alumina, zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, and antimony. Examples thereof include metal oxides such as doped tin oxide and tin-doped indium oxide; metal fluorides such as tin fluoride, calcium fluoride, and aluminum fluoride; potassium titanate, boron nitride, and the like. Among these, from the viewpoint of the hardness of the filler, the use of an inorganic filler is advantageous for improving the wear resistance.

The average primary particle size of the filler is preferably 0.01 μm to 0.5 μm from the viewpoint of light transmittance and wear resistance of the surface protective layer. When the average primary particle size of the filler is less than 0.01 μm, the dispersibility may be lowered, and the effect of improving wear resistance may not be sufficiently exhibited. When the average primary particle size exceeds 0.5 μm, the surface protective layer In the dispersion liquid, sedimentation of the filler may be promoted or toner filming may occur.
The higher the content of the filler in the surface protective layer, the better the wear resistance is, but if it is too high, the residual potential increases, the writing light transmittance of the surface protective layer decreases, and side effects occur. There is. Therefore, 50 parts by mass or less is preferable, and 30 parts by mass or less is more preferable.

  The filler can be surface-treated with at least one kind of surface treatment agent, and the surface treatment is preferable from the viewpoint of dispersibility of the filler. Decreasing the dispersibility of the filler not only increases the residual potential, but also decreases the transparency of the coating, causes defects in the coating, and decreases the wear resistance. It can develop into a big problem.

There is no restriction | limiting in particular as said surface treating agent, Although all the conventionally used surface treating agents can be used, the surface treating agent which can maintain the insulation of a filler is preferable.
About the usage-amount of the said surface treating agent, although it changes with average primary particle diameters of the filler to be used, 3 mass parts-30 mass parts are preferable in filler mass (100 mass parts), and 5 mass parts-20 mass parts are more preferable. . If the surface treatment amount is less than this, the filler dispersion effect cannot be obtained, and if the surface treatment amount is too much, the residual potential may be significantly increased.

The surface protective layer coating liquid may contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement) and a leveling agent, if necessary. Known additives can be used for these additives.
As the plasticizer, for example, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used. The amount of the plasticizer used is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less in the total solid content (100 parts by mass) of the surface protective layer coating solution.
Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount of the leveling agent used is preferably 3 parts by mass or less in the total solid content (100 parts by mass) of the surface protective layer coating solution.

  The surface protective layer is applied with a surface protective layer coating solution containing at least a polyvinyl acetal compound, a tri- or higher functional radical polymerizable monomer, and a radical polymerizable compound having a charge transporting structure, It is formed by reacting a radically polymerizable monomer with a radically polymerizable compound having a charge transporting structure and curing it to obtain a reaction product (cured product).

In addition, the said surface protective layer coating liquid is diluted with a solvent as needed, and is apply | coated.
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alcohol solvents such as methanol, ethanol, propanol and butanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. Ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran, dioxane and propyl ether; halogen solvents such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene; aromatic solvents such as benzene, toluene and xylene; methyl Cellosolve solvents such as cellosolve, ethyl cellosolve, cellosolve acetate and the like. These may be used individually by 1 type and may use 2 or more types together.
In addition, the dilution rate with the said solvent changes with the solubility of a composition, the coating method, the thickness of the target surface protective layer, etc., and can be selected suitably.

The application can be performed, for example, by a dip coating method, a spray coating method, a bead coating method, a ring coating method, or the like.
In the present invention, after applying the surface protective layer coating liquid, energy is applied from the outside and cured to form a surface protective layer. The external energy includes heat, light, and radiation.
The heat energy is applied by heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays or electromagnetic waves.

The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. When the heating temperature is less than 100 ° C., the reaction rate is slow and the reaction may not be completed completely. When the heating temperature exceeds 170 ° C., the reaction proceeds non-uniformly and a large strain is generated in the surface protective layer. . In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and further heating to 100 ° C. As the energy of the light, a UV irradiation light source such as a high pressure mercury lamp or a metal halide lamp having an emission wavelength mainly in ultraviolet light (UV) can be used, but it is visible according to the absorption wavelength of the radical polymerizable substance or the photopolymerization initiator. A light source can also be selected.
The irradiation light amount is preferably 50 mW / cm ² or more and 1,000 mW / cm ² or less. If the irradiation light amount is less than 50 mW / cm ² , it may take time for the curing reaction. If it exceeds 1,000 mW / cm ² , the progress of the reaction becomes uneven and the surface protective layer becomes rough. Sometimes. Examples of radiation energy include those using electron beams (EB). Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.
Since the thickness of the surface protective layer varies depending on the layer structure of the photoreceptor in which the surface protective layer is used, the thickness will be described in accordance with the following description of the layer structure of the electrophotographic photoreceptor.

<Layer structure of electrophotographic photoreceptor>
The layer structure of the electrophotographic photosensitive member of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of an electrophotographic photosensitive member in an image forming apparatus of the present invention. A photosensitive layer 202 having a charge generation function and a charge transport function is provided on a support 201. A structure in which a surface protective layer 203 is provided on the surface of a single layer structure is shown.
FIG. 2 is a schematic cross-sectional view showing another layer configuration example of the electrophotographic photosensitive member in the image forming apparatus of the present invention. A charge generation layer 204 having a charge generation function and a charge transport function are provided on a support 201. The surface protective layer 203 is provided on the surface of the stacked structure in which the charge transport layer 205 having the stacked structure is stacked.

(Support)
The support is not particularly limited as long as it has a volume resistance of 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. For example, aluminum, nickel, chromium, nichrome, copper Metals such as gold, silver and platinum; metal oxides such as tin oxide and indium oxide coated with film or cylindrical plastic, paper, or aluminum, aluminum alloy, nickel by vapor deposition or sputtering It is possible to use a plate made of stainless steel or the like and a tube subjected to surface treatment such as cutting, superfinishing, polishing, etc. after forming them into a raw tube by a method such as extruding and drawing them. Further, an endless nickel belt and an endless stainless steel belt disclosed in JP-A-52-36016 can also be used as a support.

Moreover, what coated and disperse | distributed conductive powder to the appropriate binder resin on the said support body can also be used as a support body.
Examples of the conductive powder include carbon black, acetylene black; metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver; metal oxide powder such as conductive tin oxide and ITO. It is done. Examples of the binder resin used at the same time include polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride resin, vinyl chloride- Vinyl acetate copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, poly-N-vinyl Examples thereof include carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. These may be used individually by 1 type and may use 2 or more types together.
The conductive layer can be provided by applying a coating liquid in which these conductive powder and binder resin are dispersed in a solvent.
Examples of the solvent include tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, and the like.
Further, heat shrinkage of the conductive powder contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. What provided the electroconductive layer with the tube can also be used suitably as a support body.

(Photosensitive layer)
The photosensitive layer may have a laminated structure or a single layer structure.
When the photosensitive layer has a laminated structure, the photosensitive layer includes a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. When the photosensitive layer has a single layer structure, the photosensitive layer is a layer having both a charge generation function and a charge transport function.
Hereinafter, each of the photosensitive layer having a laminated structure and the photosensitive layer having a single layer structure will be described.

[Photosensitive layer of laminated structure]
(Charge generation layer)
The charge generation layer includes at least a charge generation material, and includes a binder resin and, if necessary, other components.
As the charge generation material, inorganic materials and organic materials can be used.
Examples of the inorganic material include crystalline selenium, amorphous-selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and amorphous-silicon. In amorphous-silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms or phosphorus atoms are preferably used.
The organic material is not particularly limited and may be appropriately selected from known materials according to the purpose. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azurenium salt pigments, squaric acid methine Pigment, azo pigment having carbazole skeleton, azo pigment having triphenylamine skeleton, azo pigment having diphenylamine skeleton, azo pigment having dibenzothiophene skeleton, azo pigment having fluorenone skeleton, azo pigment having oxadiazole skeleton, bis Azo pigments having a stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyryl carbazole skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenyl Enirumetan pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, and bisbenzimidazole pigments. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, a polyamide resin, a polyurethane resin, an epoxy resin, a polyketone resin, a polycarbonate resin, a silicone resin, an acrylic resin, a polyvinyl butyral resin, polyvinyl Formal resin, polyvinyl ketone resin, polystyrene resin, poly-N-vinyl carbazole resin, polyacrylamide resin, and the like can be given. These may be used individually by 1 type and may use 2 or more types together.

  In addition to the binder resin described above, the charge generation layer binder resin may be a polymer charge transport material having a charge transport function, such as (1) an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, or a stilbene. Polymer materials such as polycarbonate, polyester, polyurethane, polyether, polysiloxane, and acrylic resin having a skeleton and a pyrazoline skeleton, and (2) a polymer material having a polysilane skeleton can be used.

Specific examples of the above (1) include JP-A-01-001728, JP-A-01-009964, JP-A-01-013061, JP-A-01-019049, JP-A-01-241559. JP, 04-011627, JP 04-175337, JP 04-183719, JP 04-22514, JP 04-230767, JP 04-320420, JP 05-232727, JP 05-310904, JP 06-234836, JP 06-234837, JP 06-234838, JP 06-234839, JP JP 06-234840, JP 06-234841 A, JP 06-239049 A Distribution, JP-06-236050, JP-A No. 06-2
No. 36051, No. 06-295077, No. 07-056374, No. 08-176293, No. 08-208820, No. 08-212640, No. 08-253568. JP-A-08-269183, JP-A-09-062019, JP-A-09-043883, JP-A-09-71642, JP-A-09-87376, JP-A-09-104746, JP 09-110974, JP 09-110976, JP 09-157378, JP 09-221544, JP 09-227669, JP 09-235367, JP JP 09-241369, JP 09-268226, JP 09-09. 72735, JP-A No. 09-302084, JP-A No. 09-302085 discloses a charge transport polymer material described in JP-A 09-328539 discloses the like.
Specific examples of the above (2) include, for example, those described in JP-A-63-285552, JP-A-05-19497, JP-A-05-70595, JP-A-10-73944, and the like. Examples are polysilylene polymers.

The charge generation layer may contain a low molecular charge transport material.
The low molecular charge transport material includes a hole transport material and an electron transport material.
Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2 , 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7 -Trinitrodibenzothiophene-5,5-dioxide, diphenoquinone derivatives and the like. These may be used individually by 1 type and may use 2 or more types together.
Examples of the hole transport material include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives. , Triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, and the like, and other known materials such as bisstilbene derivatives and enamine derivatives. These may be used individually by 1 type and may use 2 or more types together.

As a method for forming the charge generation layer, a vacuum thin film preparation method and a casting method from a solution dispersion system can be mentioned.
As the vacuum thin film production method, for example, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used.
As the casting method, the inorganic or organic charge generating material, and optionally binder resin, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone It can be formed by dispersing with a ball mill, attritor, sand mill, bead mill or the like using a solvent such as acetone, ethyl acetate, butyl acetate, etc., and applying the solution after diluting the dispersion appropriately. Moreover, leveling agents, such as a dimethyl silicone oil and a methylphenyl silicone oil, can be added as needed. The application can be performed by dip coating, spray coating, bead coating, ring coating, or the like.
The thickness of the charge generation layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.01 μm to 5 μm, more preferably 0.05 μm to 2 μm.

(Charge transport layer)
The charge transport layer is a layer having a charge transport function, and generally contains at least a charge transport material and a binder resin.
As the charge transport material, the electron transport material, the hole transport material, and the polymer charge transport material described in the section describing the charge generation layer can be used. In particular, the use of a polymer charge transport material is particularly useful because it shows the effect of reducing the solubility of the lower layer during coating of the surface protective layer.

  The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose.For example, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, Polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate, ethyl cellulose, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N- Examples thereof include thermoplastic or thermosetting resins such as vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin. These may be used individually by 1 type and may use 2 or more types together.

The content of the charge transport material is preferably 20 parts by mass to 300 parts by mass, and more preferably 40 parts by mass to 150 parts by mass with respect to 100 parts by mass of the binder resin. However, when a polymer charge transport material is used, it can be used alone or in combination with a binder resin.
As the solvent used for coating the lower layer portion of the charge transport layer, the same solvent as the charge generation layer can be used, but a solvent that dissolves the charge transport material and the binder resin well is suitable. These solvents may be used alone or in combination of two or more. In addition, the same coating method as that for the charge generation layer can be used to form the lower layer portion of the charge transport layer.
If necessary, a plasticizer and a leveling agent can be added.

As the plasticizer, for example, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 30 parts by mass or less with respect to 100 parts by mass of the binder resin. Is preferred.
Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain, and the amount used is 100 parts by mass of the binder resin. The amount is preferably 1 part by mass or less.
The thickness of the lower layer portion of the charge transport layer is preferably 5 μm to 40 μm, and more preferably 10 μm to 30 μm.

When the surface protective layer is the surface (surface portion) of the charge transport layer, as described in the method for preparing the surface protective layer, a coating containing the radical polymerizable composition on the lower layer portion of the charge transport layer. After applying the working liquid and drying as necessary, the curing reaction is started by external energy such as heat or light, and a surface protective layer is formed.
The thickness of the surface protective layer is preferably 1 μm to 20 μm, and more preferably 2 μm to 10 μm. If the thickness is less than 1 μm, the durability may vary due to thickness unevenness, and if it exceeds 20 μm, the entire thickness of the charge transport layer may be increased and image reproducibility may be reduced due to charge diffusion.

<Single layer photosensitive layer>
The photosensitive layer having a single layer structure is a layer having a charge generation function and a charge transport function at the same time, and is usefully used by providing the surface protective layer of the present invention on the photosensitive layer.
A photosensitive layer having a single-layer structure can be formed by dissolving or dispersing a charge generating material having a charge generating function, a charge transporting material having a charge transporting function, and a binder resin in an appropriate solvent, applying the solution, and drying. . Moreover, a plasticizer, a leveling agent, etc. can also be added as needed. As the charge generation material dispersion method, the charge generation material, the charge transport material, the plasticizer, and the leveling agent, the same charge generation layer and charge transport layer as those already described can be used. As the binder resin, in addition to the binder resin previously mentioned in the charge transport layer, the binder resin mentioned in the charge generation layer may be mixed and used. In addition, the polymer charge transport materials listed above can also be used, which is useful in that contamination of the photosensitive layer composition into the surface protective layer can be reduced.
There is no restriction | limiting in particular in the thickness of the said photosensitive layer, According to the objective, it can select suitably, 5 micrometers-30 micrometers are preferable, and 10 micrometers-25 micrometers are more preferable.

  The charge generation material contained in the photosensitive layer having a single layer structure is preferably 1 part by mass to 30 parts by mass in the total amount (100 parts by mass) of the photosensitive layer, and the binder resin contained in the photosensitive layer is the total amount of the photosensitive layer ( 100 parts by mass), 20 parts by mass to 80 parts by mass are preferable, and 10 parts by mass to 70 parts by mass of the charge transport material are preferably used.

(Middle layer)
In the electrophotographic photoreceptor of the present invention, it is possible to provide an intermediate layer between the surface protective layer and the charge transport layer, or between the surface protective layer and the single-layered photosensitive layer.
The intermediate layer prevents inhibition of the curing reaction and unevenness of the surface protective layer caused by mixing of the photosensitive layer composition in the surface protective layer containing the radical polymerizable composition. It is also possible to improve the adhesion between the photosensitive layer and the surface protective layer.

The intermediate layer generally contains a binder resin as a main component. Examples of the binder resin include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol.
There is no restriction | limiting in particular as a formation method of the said intermediate | middle layer, The coating method generally used can be employ | adopted.
There is no restriction | limiting in particular in the thickness of the said intermediate | middle layer, According to the objective, it can select suitably, 0.05 micrometers-2 micrometers are preferable.

(Underlayer)
In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided on the support.
The undercoat layer generally contains a resin as a main component, and further contains other components as necessary. The resin is a resin having a high solvent resistance with respect to a general organic solvent in consideration of applying a surface protective layer, a photosensitive layer, a charge generation layer, or an intermediate layer with a solvent on the undercoat layer. It is preferable.

The resin is not particularly limited and may be appropriately selected depending on the purpose. For example, water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble such as copolymer nylon and methoxymethylated nylon Examples include resins, polyurethanes, melamine resins, phenol resins, alkyd-melamine resins, epoxy resins, and other curable resins that form a three-dimensional network structure.
To the undercoat layer, fine powder pigments of metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added for preventing moire and reducing residual potential.

The undercoat layer can be formed using a solvent and a coating method in the same manner as the photosensitive layer.
As the undercoat layer, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can also be used. In addition, the undercoat layer is provided with Al ₂ O ₃ by anodic oxidation, organic substances such as polyparaxylylene (parylene), and inorganic substances such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2. Can also be used satisfactorily. In addition, known ones can be used.
There is no restriction | limiting in particular in the thickness of the said undercoat layer, According to the objective, it can select suitably, 5 micrometers or less are preferable.

  In the present invention, in order to improve environmental resistance, a photosensitive layer, a surface protective layer, a charge generation layer, a charge transport layer, an undercoat layer having a single layer structure are used for the purpose of preventing a decrease in sensitivity and an increase in residual potential. An antioxidant can be added to each layer such as an intermediate layer.

Examples of the antioxidant include phenolic compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, and organic phosphorus compounds. These may be used individually by 1 type and may use 2 or more types together.
Examples of the phenol compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl- 6-t-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3 -Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy Ben ) Benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3 ′) -T-butylphenyl) butyric acid] glycol ester, tocopherols, and the like.
Examples of the paraphenylenediamines include N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl- p-phenylenediamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like.
Examples of the hydroquinones include 2,5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methyl. And hydroquinone and 2- (2-octadecenyl) -5-methylhydroquinone.
Examples of the organic sulfur compounds include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like. It is done.
Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.
In addition, these compounds are known as antioxidants, such as rubber | gum, a plastic, and fats and oils, and a commercial item can be obtained easily.
There is no restriction | limiting in particular in the addition amount of the said antioxidant, According to the objective, it can select suitably, 0.01 mass part-10 mass parts are preferable with respect to the total mass of the layer to add.

[toner]
The toner suitably used in the image forming apparatus of the present invention is obtained by adhering silica fine particles hydrophobized to the surface of toner base particles containing at least a binder resin and a colorant. That is, at least one or more types of silica fine particles that have been subjected to hydrophobic treatment adhere to the surface of the toner base particles.
The toner base particles used in the present invention can be kneaded and pulverized by melting and kneading a resin, pigment, charge control agent, and release agent, cooling and then pulverizing and classifying, but the particle size and shape are uniform. Therefore, it is more preferable to use those prepared using a polymerization toner method such as an emulsion polymerization method or a dissolution suspension method.
Hereinafter, a polyester polymerization toner is taken as an example, and its constituent materials and manufacturing methods will be specifically described.

<Polyester>
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound.
Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable.

Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.), alkylene ether glycol (diethylene glycol). , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.), alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.), alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol, Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide) adducts.
Of these, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is combined use with.
As trihydric or higher polyhydric alcohol (TO), trihydric or higher polyhydric aliphatic alcohol (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.), trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.), and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred.

Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.), alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.), aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) , Naphthalenedicarboxylic acid, etc.). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms.
Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polyvalent carboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid).
In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.
The polycondensation reaction of polyhydric alcohol (PO) and polycarboxylic acid (PC) is heated to 150-280 ° C in the presence of a known esterification catalyst such as tetrabutoxy titanate, dibutyltin oxide, etc. The produced water is distilled off to obtain a polyester having a hydroxyl group.

The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20.
By giving an acid value, it tends to be negatively chargeable, and further, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.
The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

  The polyester preferably contains a urea-modified polyester in addition to the unmodified polyester obtained by the above polycondensation reaction. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.), alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) ), Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.), araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.), isocyanates, phenol derivatives, oximes, Examples thereof include those blocked with caprolactam and the like and combinations of two or more thereof.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

  The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40% by mass, preferably 1 to 30% by mass, more preferably 2 to 20% by mass. %. If it is less than 0.5% by mass, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40% by mass, the low-temperature fixability deteriorates.

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having isocyanate groups is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. It is. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

  Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acids B1 to B5 blocked (B6).

  Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.) and alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.) and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine.

  Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the B1 to B5 amino group blocked (B6) include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. If [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.

  The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

  The urea-modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.

  When reacting the above (PIC) and when reacting (A) and (B), a solvent may be used if necessary. For example, aromatic solvents (toluene, xylene, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.), and ethers (tetrahydrofuran, etc.) A solvent inert to isocyanate (PIC) such as) can be used.

  In addition, in the crosslinking and / or elongation reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator may be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight.

  When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.
The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.
In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

<Colorant>
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine B, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Lid Russian nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used.

The content of the colorant is usually 1 to 15% by mass, preferably 3 to 10% by mass with respect to the toner. The colorant can also be used as a master batch combined with a resin.
As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be used, and these can be used alone or in combination.

<Charge control agent>
Any known charge control agent can be used. For example, nigrosine dye, triphenylmethane dye, chromium-containing metal complex dye, molybdate chelate pigment, rhodamine dye, alkoxy amine, quaternary ammonium salt (including fluorine-modified quaternary ammonium salt), alkylamide, phosphorus Simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, salicylic acid derivative metal salt, and the like.

  Specifically, Bontron 03 of nigrosine dye, Bontron P-51 of quaternary ammonium salt, Bontron S-34 of metal-containing azo dye, E-82 of oxynaphthoic acid metal complex, E- of salicylic acid metal complex 84, E-89 of phenol-based condensate (above, manufactured by Orient Chemical Co., Ltd.), TP-302, TP-415 of quaternary ammonium salt molybdenum complex (made of Hodogaya Chemical Co., Ltd.), quaternary ammonium salt Copy charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) ), Copper phthalocyanine, perylene, quinacridone, azo Pigment, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.

  The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, it shall be the range of 0.2-5 mass parts. When the amount exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

<Release agent>
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil.
Examples of such a wax component include the following.
Waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, and petrolatum. And petroleum wax.
In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used.
Furthermore, 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, fatty acid amides such as chlorinated hydrocarbons, and low molecular weight crystalline polymer resins, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be applied.
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, or may be added when dissolved and dispersed in an organic solvent.

<Manufacturing method>
Next, a toner manufacturing method will be described. In the following, specific examples are shown, and the toner manufacturing method applied to the present invention is not limited to the following.

(A) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone or the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are suitable.
The usage-amount of an organic solvent is 0-300 mass parts normally with respect to 100 mass parts of polyester prepolymers, Preferably it is 0-100 mass parts, More preferably, it is 25-70 mass parts.

(B) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.
Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.

  As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, fatty acid amide derivatives, polyhydric alcohols Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine It is below.

Moreover, the effect can be exhibited in a very small amount by using a surfactant having a fluoroalkyl group.
Suitable anionic surfactants having a fluoroalkyl group include fluoroalkylcarboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11). Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carboxylic acid And metal salts, perfluoroalkyl carboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctane sulfonic acid diethanolamide, N-propyl-N- (2 -Hydroxyethyl) perfluorooctane Sulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. .
Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.) 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  In addition, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a fluoroalkyl group right Salt, benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Smoke), Megafuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products Co., Ltd.), Footgent F-300 (Neos Co., Ltd.) and the like.

The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%.
For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao Corporation), SGP (manufactured by Soken Co., Ltd.), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.).
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid.
For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic single monomers Mer, for example, acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ -Hydroxypropyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Contains lylic acid ester, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, for example, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or contains vinyl alcohol and carboxyl group Esters of compounds such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone , Nitrogen-containing compounds such as vinylimidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, polyoxy Lopylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene Polyoxyethylenes such as nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

The dispersion method is not particularly limited, and any of known methods such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied.
Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

(C) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

(D) After completion of the above reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. .
Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as washing with water after dissolving the calcium phosphate salt with an acid such as hydrochloric acid. Remove. It can also be removed by an operation such as degradation with an enzyme.

(E) In the present invention, hydrophobic silica is attached (attached) to the toner base particles obtained as described above by mixing and stirring to obtain a toner.
The external additive attached to the toner surface is preferably hydrophobic silica having a primary average particle size of 100 to 200 nm. When the primary average particle size is 100 nm or less, the toner cleaning property is deteriorated and a streak-like abnormal image is generated.
The primary average particle diameter in hydrophobic silica can be determined by measuring the diameter of 50 particles from an observation image using an electrophotographic microscope such as SEM or TEM and deriving the average value.

  Hydrophobic silica means a surface treatment to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. As a surface treatment agent, for example, a silane coupling agent, Examples include silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, and modified silicone oils.

The degree of hydrophobicity is preferably 50 to 90%. When the degree of hydrophobicity is less than 50%, the toner charge leakage under high temperature and high humidity increases, and toner scattering and photoreceptor fogging are likely to occur. On the other hand, if the degree of hydrophobicity is greater than 90%, the toner tends to be excessively charged under low temperature and low humidity, which may cause image density defects. Further, the presence of excess hydrophobizing agent has an adverse effect such as poor toner fluidity.
The method for measuring the degree of hydrophobicity is shown below.

(Measurement method of degree of hydrophobicity)
Add 50 ml of water to a 200 ml beaker and add 0.2 g of external additive fine particles. Then, while gently stirring with a magnetic stirrer, methanol was added from the burette whose tip was immersed in water at the time of dropping, and the floating external additive fine particles began to sink. Read and calculate from the following formula.
Hydrophobicity (%) = [ml of methanol dropped / (50 + ml of methanol dropped)] × 100

Furthermore, in addition to the hydrophobic silica, other external additives can be used in combination. Examples of the inorganic fine particles include silica, alumina, titania, barium titanate, magnesium titanate, calcium titanate, and titanic acid. Strontium, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, carbonized Examples thereof include silicon and silicon nitride.
The content of the external additive in the toner is preferably 0.01 to 5.0% by weight, and more preferably 0.01 to 2.0% by weight.

[Image forming apparatus]
The image forming apparatus of the present invention includes at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit, and a cleaning unit, and further appropriately selected as necessary. The other means, for example, a static elimination means, a recycling means, a control means, etc. are provided. The charging unit and the exposure unit may be collectively referred to as an electrostatic latent image forming unit.

(Electrostatic latent image forming means)
The electrostatic latent image forming unit is a unit that forms an electrostatic latent image on the electrophotographic photosensitive member.
As the electrophotographic photoreceptor, the electrophotographic photoreceptor of the present invention is used.
The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrophotographic photosensitive member and then performing imagewise exposure, and can be performed by the electrostatic latent image forming unit. it can.
The electrostatic latent image forming means includes at least a charger that uniformly charges the surface of the electrophotographic photosensitive member and an exposure device that exposes the surface of the electrophotographic photosensitive member imagewise.
The charging can be performed, for example, by applying a voltage to the surface of the electrophotographic photosensitive member using the charger.

  The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roller, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotrons and corotrons.

  The shape of the charging member may take any form such as a magnetic brush or a fur brush in addition to the roller, and can be selected according to the specifications and form of the electrophotographic apparatus. In the case of using a magnetic brush, the magnetic brush is composed of, for example, various ferrite particles such as Zn-Cu ferrite as a charging member, and a non-magnetic conductive sleeve for supporting the same, and a magnet roll included therein. . Or, when using a brush, for example, as a material of the fur brush, a fur treated with carbon, copper sulfide, metal or metal oxide is used, and this is wound or attached to a metal or other conductive core. To make a charger.

The charger is not limited to the contact charger as described above. However, since an image forming apparatus in which ozone generated from the charger is reduced is obtained, a contact charger is used. preferable.
It is preferable that the charger is disposed in contact or non-contact with the electrophotographic photosensitive member and charges the surface of the electrophotographic photosensitive member by applying a direct current and an alternating voltage.
The charging device is a charging roller that is disposed in close proximity to the electrophotographic photosensitive member via a gap tape, and charges the surface of the electrophotographic photosensitive member by applying a direct current and an alternating voltage to the charging roller. Those are preferred.

The exposure can be performed, for example, by exposing the surface of the electrophotographic photosensitive member imagewise using the exposure device.
The exposure device is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charger can be exposed like an image to be formed, and can be appropriately selected according to the purpose. However, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system can be used.
In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.

(Development means)
The developing means is means for developing the electrostatic latent image with the toner or developer to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the toner or developer, and can be performed by the developing unit.
The developing unit is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. Preferred examples include those having at least a developing unit capable of bringing the toner or developer into contact or non-contact with the electrostatic latent image.

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a toner having a stirrer for charging the toner or the developer by frictional stirring and a rotatable magnet roller is preferable.

  In the developing unit, for example, the toner and the carrier are mixed and stirred, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted to the electrophotographic photosensitive member. Move to the surface of the body. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.

As the developer to be accommodated in the developing device, the toner produced by the method described above is used.
In recent years, in order to achieve high image quality, a toner having a small particle size and a nearly spherical shape has been used. However, in the present invention, since toner cleaning becomes difficult, the primary average particle size is 100 to 200 nm. By using hydrophobic silica as an external additive on the toner surface, the effect of improving the cleaning property and reducing the adhesion between the photoreceptor and the toner or between the intermediate transfer belt and the toner is achieved. Further, the adhesion force between the toners can be reduced, and the fluidity and charging characteristics can be improved.

  However, the silica easily adheres to the surface of the electrophotographic photosensitive member, and further, the adhered silica gradually accumulates or the toner resin adheres, so that an abnormal image in which the attached matter appears as an image is likely to be generated. Therefore, an electrophotographic photoreceptor using a surface protective layer comprising at least a trifunctional or higher functional radical polymerizable monomer of the present invention and a radical polymerizable compound having a charge transporting structure, and a polyvinyl acetal compound, and a toner base An excellent releasability can be obtained by using a toner in which at least one kind of hydrophobized silica fine particles are adhered to the surface of the particles, so that a good image without abnormal images can be obtained. It becomes possible.

(Transfer means)
The transfer means is a means for transferring the visible image to a recording medium. The intermediate recording medium is used to primarily transfer the visible image onto the intermediate recording medium, and then the visible image is transferred onto the recording medium. A primary transfer unit for forming a composite transfer image by transferring a visible image onto an intermediate recording medium using two or more colors, preferably a full color toner, as the toner, and a composite transfer image; An embodiment including a secondary transfer unit that transfers a transfer image onto a recording medium is more preferable.

The transfer can be performed, for example, by charging the electrophotographic photosensitive member with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer unit includes a primary transfer unit that transfers a visible image onto an intermediate recording medium to form a composite transfer image, and a secondary transfer unit that transfers the composite transfer image onto a recording medium. Embodiments are preferred.
The intermediate recording medium is not particularly limited and may be appropriately selected from known recording media according to the purpose. For example, a transfer belt or the like is preferable.

The transfer unit (the primary transfer unit and the secondary transfer unit) includes at least a transfer unit that peels and charges the visible image formed on the electrophotographic photosensitive member toward the recording medium. preferable. There may be one transfer means or two or more transfer means.
Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and can be appropriately selected according to the purpose. PET for OHP A base or the like can also be used.

(Fixing means)
The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing device, and may be performed each time the toner of each color is transferred to the recording medium, or for the toner of each color. You may perform this simultaneously in the state which laminated | stacked this.
There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

(Static removal means)
The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrophotographic photosensitive member, and can be suitably performed by a neutralization unit.
The neutralizing means is not particularly limited and may be appropriately selected from known neutralizers as long as it can apply a neutralizing bias to the electrophotographic photosensitive member. For example, a neutralizing lamp is preferably used. Can be mentioned.

(Cleaning means)
The cleaning step is a step of removing the electrophotographic toner remaining on the electrophotographic photosensitive member, and can be suitably performed by a cleaning unit.
The cleaning means is not particularly limited, and may be selected from known cleaners as long as the electrophotographic toner remaining on the electrophotographic photosensitive member can be removed. For example, a magnetic brush cleaner Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

(Recycling means)
The recycling step is a step of recycling the electrophotographic color toner removed in the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

(Control means)
The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

  The image forming apparatus of the present invention uses the electrophotographic photosensitive member having the surface protective layer according to the present invention. For example, the toner image on the recording medium (transfer paper) is obtained after at least charging, image exposure, and development of the photosensitive member. The image forming apparatus includes processes of transferring, fixing, and cleaning the surface of the photoreceptor. In some cases, an image forming method or the like in which an electrostatic latent image is directly transferred to a transfer member and developed does not necessarily have the above-described process arranged on a photosensitive member.

Here, FIG. 3 is a schematic view showing an example of the image forming apparatus of the present invention.
A charging roller 3 is used as a means for charging the photoconductor on average. As other charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known method can be used.

  Next, the image exposure unit 5 is used to form an electrostatic latent image on the uniformly charged photoreceptor 1. As the light source, all luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Next, the developing unit 6 is used to visualize the electrostatic latent image formed on the photoreceptor 1. Development methods include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

  Next, a transfer charger 10 is used to transfer the toner image visualized on the photoreceptor onto the recording medium 9. In addition, a pre-transfer charger may be used for better transfer. As these transfer means, a transfer charger, an electrostatic transfer method using a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used.

  Next, a separation charger or a separation claw is used as means for separating the recording medium 9 from the photoreceptor 1. As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger, the charging means can be used.

  Next, a fur brush or a cleaning blade 15 is used to clean the toner remaining on the photoconductor after transfer. In addition, a pre-cleaning charger may be used for more efficient cleaning. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination.

Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, the charge removal lamp 2 and the charge removal charger are used, and the exposure light source and the charging means can be used respectively. In addition, the code | symbol 8 in FIG. 3 shows a registration roller.
In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.
The present invention is an image forming apparatus using such an image forming unit.
The image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and made detachable.

(Process cartridge)
A process cartridge according to the present invention includes the electrophotographic photosensitive member according to the present invention and at least one means selected from a charging unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. Detachable.
FIG. 4 is a schematic view showing an example of the process cartridge of the present invention.

  The process cartridge shown in FIG. 4 incorporates the electrophotographic photosensitive member (photosensitive drum) 101 of the present invention, charging means (charging device) 102, developing means (developing device) 104, transfer means (transfer device) 106, and cleaning means. A (cleaning blade) 107 is included, and other means are provided as necessary. In FIG. 4, reference numeral 103 denotes exposure means (exposure), and 105 denotes a recording medium.

Next, the image forming process using the process cartridge shown in FIG. 4 will be described. The electrophotographic photosensitive member 101 has its surface formed by charging by the charging means 102 and exposure 103 by the exposure means (not shown) while rotating in the direction of the arrow. Then, an electrostatic latent image corresponding to the exposure image is formed.
The electrostatic latent image is developed by the developing unit 104, and the obtained visible image is transferred to the recording medium 105 by the transfer unit 108 and printed out. Next, the surface of the electrophotographic photosensitive member after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  Since the image forming apparatus and the process cartridge of the present invention use an electrophotographic photosensitive member having a surface protective layer having high wear resistance, smooth surface properties, and almost no variation in electrical characteristics, an image due to wear is used. Deterioration can be suppressed, and high-definition and high-quality images can be formed over a long period of time.

Examples of the present invention will be described below, but the present invention is not limited to these examples. “Parts” are all parts by mass. Hereinafter, Examples 5 and 6 are referred to as Reference Examples 5 and 6, which are not included in the present invention.
First, for evaluation with an image forming apparatus, a toner and an electrophotographic photoreceptor used for the evaluation were prepared as follows.

[Toner Production Example 1]
(Preparation of base particles)
229 parts of bisphenol A ethylene oxide 2-mole adduct, 529 parts of bisphenol A propion oxide 3-mole adduct, 208 parts of terephthalic acid, 46 parts of adipic acid and dibutyltin oxide 2 parts were added and reacted at 230 ° C. under normal pressure for 8 hours. Next, after reacting under reduced pressure of 10 to 15 mmHg for 5 hours, 44 parts of trimellitic anhydride was added to the reaction vessel and reacted at 180 ° C. for 2 hours under normal pressure to synthesize an unmodified polyester resin. .
The obtained unmodified polyester resin had a number average molecular weight of 2500, a weight average molecular weight of 6700, a glass transition temperature of 43 ° C., and an acid value of 25 mgKOH / g.

  1200 parts of water, 540 parts of carbon black Printex 35 (manufactured by Dexa; DBP oil absorption = 42 ml / 100 mg, pH = 9.5) and 1200 parts of unmodified polyester resin were mixed using a Henschel mixer (manufactured by Mitsui Mining). . The resulting mixture was kneaded at 150 ° C. for 30 minutes using two rolls, then rolled and cooled, and pulverized with a pulverizer (manufactured by Hosokawa Micron Corporation) to prepare a master batch.

  In a reaction vessel equipped with a stirrer and a thermometer, 378 parts of unmodified polyester resin, 110 parts of carnauba wax, 22 parts of salicylic acid metal complex E-84 (manufactured by Orient Chemical Co., Ltd.) and 947 parts of ethyl acetate were charged and stirred. The temperature was raised to 80 ° C., held at 80 ° C. for 5 hours, and then cooled to 30 ° C. over 1 hour. Next, 500 parts of a master batch and 500 parts of ethyl acetate were charged into the reaction vessel and mixed for 1 hour to obtain a raw material solution.

  1324 parts of the obtained raw material solution was transferred to a reaction vessel, and filled with 80% by volume of 0.5 mm zirconia beads using a bead mill Ultra Visco Mill (manufactured by Imex Co., Ltd.). 3 passes under the condition of 6 m / sec. I. Pigment Red and carnauba wax were dispersed to obtain a wax dispersion.

Next, 1324 parts of a 65 mass% ethyl acetate solution of an unmodified polyester resin was added to the wax dispersion. A layered inorganic mineral montmorillonite (Clayton APA; Southern) modified with a quaternary ammonium salt having at least a part of a benzyl group in 200 parts of a dispersion obtained by one pass using Ultraviscomil under the same conditions as described above. 3 parts of Cray Products) was added. K. The mixture was stirred for 30 minutes using a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a toner material dispersion.
The viscosity of the obtained dispersion of toner material was measured as follows.

Using a parallel plate type rheometer AR2000 (made by D.A. Instruments Japan Co., Ltd.) equipped with a parallel plate with a diameter of 20 mm, the gap was set to 30 μm, and the toner material dispersion was at 25 ° C. After applying a shear force for 30 seconds at a shear rate of 30000 sec-1, viscosity (viscosity A) was measured when the shear rate was changed from 0 sec-1 to 70 sec-1 in 20 seconds. Further, using a parallel plate rheometer AR2000, the viscosity (viscosity B) when a shearing force was applied to the dispersion of the toner material at 25 ° C. for 30 seconds at a shear rate of 30000 seconds ⁻¹ was measured.

In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 682 parts of bisphenol A ethylene oxide 2-mole adduct, 81 parts of bisphenol A propylene oxide 2-mole adduct, 283 parts of terephthalic acid, 22 parts of trimellitic anhydride And 2 parts of dibutyltin oxide were added and reacted at 230 ° C. for 8 hours under normal pressure. Next, it was made to react under reduced pressure of 10-15mHg for 5 hours, and the intermediate polyester resin was synthesize | combined.
The obtained intermediate polyester resin had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, a glass transition temperature of 55 ° C., an acid value of 0.5 mgKOH / g, and a hydroxyl value of 51 mgKOH / g.

  Next, 410 parts of the intermediate polyester resin, 89 parts of isophorone diisocyanate, and 500 parts of ethyl acetate are charged into a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introduction pipe, and reacted at 100 ° C. for 5 hours. Was synthesized. The free isocyanate content of the obtained prepolymer was 1.53% by mass.

  In a reaction vessel equipped with a stir bar and a thermometer, 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to synthesize a ketimine compound. The amine value of the obtained ketimine compound was 418 mgKOH / g.

  In a reaction vessel, 749 parts of a dispersion of toner material, 115 parts of a prepolymer and 2.9 parts of a ketimine compound are charged and mixed at 5,000 rpm for 1 minute using a TK homomixer (manufactured by Tokushu Kika). A mixture was obtained.

  In a reaction vessel equipped with a stirring bar and a thermometer, 683 parts of water, 11 parts of reactive emulsifier (sodium salt of sulfuric acid ester of methacrylic acid ethylene oxide adduct), Eleminol RS-30 (manufactured by Sanyo Chemical Industries), styrene 83 Parts, 83 parts of methacrylic acid, 110 parts of butyl acrylate and 1 part of ammonium persulfate were stirred at 400 rpm for 15 minutes to obtain an emulsion. The emulsion was heated, heated to 75 ° C. and reacted for 5 hours. Next, 30 parts of a 1% by mass ammonium persulfate aqueous solution was added and aged at 75 ° C. for 5 hours to prepare a resin particle dispersion.

  Next, 990 parts of water, 83 parts of a resin particle dispersion, 37 parts of a 48.5% by weight aqueous solution of sodium dodecyl diphenyl ether disulfonate, Eleminol MON-7 (manufactured by Sanyo Chemical Industries), 1 mass of a polymer dispersant sodium carboxymethyl cellulose % Aqueous solution serogen BS-H-3 (Daiichi Kogyo Seiyaku Co., Ltd.) 135 parts and ethyl acetate 90 parts were mixed and stirred to obtain an aqueous medium.

To 1200 parts of the obtained aqueous medium, 867 parts of an oil phase mixed liquid was added and mixed at 13000 rpm for 20 minutes using a TK homomixer to prepare a dispersion (emulsified slurry).
Furthermore, the emulsified slurry was charged into a reaction vessel equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 8 hours, aging was performed at 45 ° C. for 4 hours to obtain a dispersed slurry. Subsequently, 100 parts by mass of the dispersion slurry was filtered under reduced pressure, 100 parts of ion-exchanged water was added to the filter cake, mixed at 12000 rpm for 10 minutes using a TK homomixer, and then filtered.
To the obtained filter cake, 10% by mass hydrochloric acid was added to adjust the pH to 2.8, and the mixture was mixed for 10 minutes at 12,000 rpm using a TK homomixer, followed by filtration. Furthermore, 300 parts of ion-exchanged water was added to the obtained filter cake, mixed for 10 minutes at 12000 rpm using a TK homomixer, and then filtered twice to obtain a final filter cake.
The obtained final filter cake was dried at 45 ° C. for 48 hours using a circulating drier and sieved with a mesh having a mesh size of 75 μm to obtain toner base particles.
Hydrophobized silica fine particles were attached (attached) to the surface of the obtained toner base particles as follows.

(Adhesion of external additives)
To 100 parts of the obtained toner base particles, 1.5 parts of hydrophobic silica surface-treated with hexamethyldisilazane having a hydrophobicity of 65% and an average primary particle size of 120 nm are added, and a Henschel mixer (Mitsui Mining Co., Ltd.) is added. For 3 minutes under the condition of a peripheral speed of 33 m / s. The mixed powder was passed through a mesh with a mesh size of 38 μm to remove coarse powder, and an electrostatic charge image developing toner 1 externally added with hydrophobic fine powder was produced.

[Toner Production Example 2]
An electrostatic charge image developing toner 2 was produced in the same manner as in Toner Production Example 1 except that the following external additives were attached (attached).
(Adhesion of external additives)
To 100 parts of the obtained toner base particles, 1.5 parts of hydrophobic silica surface-treated with hexamethyldisilazane having a hydrophobicity of 65% and an average primary particle diameter of 200 nm are added, and a Henschel mixer (Mitsui Mining Co., Ltd.) is added. For 3 minutes under the condition of a peripheral speed of 33 m / s. The mixed powder was passed through a mesh having a mesh size of 38 μm to remove coarse powder, and an electrostatic charge image developing toner 2 externally added with hydrophobic fine powder was produced.

[Toner Production Example 3]
An electrostatic charge image developing toner 3 was produced in the same manner as in Toner Production Example 1 except that the following external additives were attached (attached).
(Attachment of external additives)
To 100 parts of the obtained toner base particles, 1.5 parts of hydrophobic silica having a surface treatment with hexamethyldisilazane of 65% and an average primary particle diameter of 70 nm are added, and a Henschel mixer (Mitsui Mining Co., Ltd.) is added. For 3 minutes under the condition of a peripheral speed of 33 m / s. The mixed powder was passed through a mesh having a mesh size of 38 μm to remove a coarse powder, and an electrostatic charge image developing toner 3 was prepared by externally adding a hydrophobic fine powder.

[Toner Production Example 4]
An electrostatic charge image developing toner 4 was produced in the same manner as in Toner Production Example 1 except that the following external additives were attached (attached).
(Adhesion of external additives)
To 100 parts of the obtained toner base particles, 1.5 parts of hydrophobic silica surface-treated with hexamethyldisilazane having a hydrophobicity of 65% and an average primary particle diameter of 250 nm are added, and a Henschel mixer (Mitsui Mining Co., Ltd.) is added. For 3 minutes under the condition of a peripheral speed of 33 m / s. The mixed powder was passed through a mesh having a mesh size of 38 μm to remove coarse powder, and an electrostatic charge image developing toner 4 to which hydrophobic fine powder was externally added was prepared.

[Toner Production Example 5]
An electrostatic charge image developing toner 5 was produced in the same manner as in Toner Production Example 1 except that the following external additives were attached (attached).
(Adhesion of external additives)
To 100 parts of the obtained toner base particles, 1.5 parts of silica having an average primary particle diameter of 140 nm without surface treatment is added, and a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) is used at a peripheral speed of 33 m / s. Mixed for 3 minutes. The mixed powder was passed through a mesh having a mesh size of 38 μm to remove a coarse powder, and an electrostatic charge image developing toner 5 was prepared by adding a hydrophobic fine powder externally.

[Photosensitive member production example 1]
<Production of electrophotographic photoreceptor>
An undercoating layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition are sequentially applied onto an aluminum cylinder by dip coating, dried, and coated with a thickness of 3.5 μm. A charge generation layer having a thickness of 0.2 μm, and a charge transport layer having a thickness of 23 μm were formed.

[Undercoat layer coating solution]
Alkyd resin (Beccosol 1307-60-EL;
Dainippon Ink & Chemicals, Inc.) 6 parts by mass Melamine resin (Super Becamine G-821-60;
Dainippon Ink & Chemicals, Inc.) 4 parts by mass Titanium oxide 40 parts by mass Methyl ethyl ketone 50 parts by mass

[Charge generation layer coating solution]
-Bisazo pigment represented by the following structural formula (2)-2.5 parts by mass-Polyvinyl butyral (XYHL; manufactured by UCC)-0.5 part by mass-Cyclohexanone-200 parts by mass-Methyl ethyl ketone- ..80 parts by mass

[Charge transport layer coating solution]
-Bisphenol Z-type polycarbonate (Panlite TS-2050; manufactured by Teijin Chemicals Ltd.)-10 parts by mass-Charge transport material represented by the following structural formula (3)-7 parts by mass-Tetrahydrofuran ... 100 1 part by mass of 1 part by mass of a tetrahydrofuran solution of silicone oil (KF50-100CS; manufactured by Shin-Etsu Chemical Co., Ltd.)

Next, spray coating is performed on the charge transport layer using a surface protective layer coating solution having the following composition, and light irradiation is performed under the conditions of a metal halide lamp, irradiation intensity: 500 mW / cm ² , and irradiation time: 20 seconds. And dried at 130 ° C. for 30 minutes to form a surface protective layer having a thickness of 4.0 μm. Thus, the electrophotographic photoreceptor 1 was produced.
In addition, regarding the polyvinyl acetal compound (polyvinyl acetal resin) in the following surface protective layer coating liquid, the composition ratio n of the repeating unit containing a glass transition temperature, a molecular weight (number average molecular weight), and a hydroxyl group (hereinafter referred to as “hydroxyl group amount”) (Abbreviation).

[Surface protective layer coating solution]
-Polyvinyl acetal resin [ESREC BX-1; manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 90 ° C., molecular weight 100,000, hydroxyl group content 33 mol%)] ... 20 parts by mass. Trifunctional or higher radical polymerizable compound [(trimethylolpropane triacrylate),
TMPTA; manufactured by Tokyo Chemical Industry Co., Ltd.]] ... 75 parts by mass-Radically polymerizable compound having a charge transporting structure (Exemplary Compound No. 7) ... 95 parts by mass-Photopolymerization initiator [(1-hydroxy- Cyclohexyl-phenyl-ketone),
Irgacure 184; manufactured by Ciba Specialty Chemicals)] ... 10 parts by mass-Tetrahydrofuran ... 1,200 parts by mass

[Photoconductor Preparation Example 2]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 2 was produced in the same manner as in the photoreceptor preparation example 1 except that the polyvinyl acetal compound was changed to the following in the surface protective layer coating solution of the photoreceptor preparation example 1.
・ Polyvinyl acetal resin [SREC BX-5, manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 86 ° C, molecular weight 130,000, hydroxyl content 33 mol%)] ... 20 parts by mass

[Photoconductor Preparation Example 3]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 3 was produced in the same manner as in the photoreceptor preparation example 1 except that the polyvinyl acetal compound in the surface protective layer coating solution of the photoreceptor preparation example 1 was changed to the following.
-Polyvinyl acetal resin [ESREC KS-5; manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 110 ° C, molecular weight 130,000, hydroxyl group content 25 mol%)] ... 20 parts by mass

[Photoconductor Preparation Example 4]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 4 was produced in the same manner as in the photoreceptor preparation example 1 except that the polyvinyl acetal compound was changed to the following in the surface protective layer coating solution of the photoreceptor preparation example 1.
-Polyvinyl acetal resin [ESREC KS-3; manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 110 ° C., molecular weight 108,000, hydroxyl group content 25 mol%)] ... 20 parts by mass

[Photoconductor Preparation Example 5]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 5 was produced in the same manner as in the photoreceptor preparation example 1 except that the polyvinyl acetal compound was changed to the following in the surface protective layer coating solution of the photoreceptor preparation example 1.
・ Polyvinyl acetal resin [ESREC BX-L; manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 74 ° C, molecular weight 20,000, hydroxyl group content 37 mol%)] ... 20 parts by mass

[Photoconductor Preparation Example 6]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 6 was produced in the same manner as in the photoreceptor preparation example 1 except that the polyvinyl acetal compound was changed to the following in the surface protective layer coating solution of the photoreceptor preparation example 1.
・ Polyvinyl acetal resin [SREC BH-S manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 64 ° C, molecular weight 66,000, hydroxyl group content 22 mol%)] ... 20 parts by mass

[Photoconductor Preparation Example 7]
<Production of electrophotographic photoreceptor>
The electrophotographic photosensitive member 7 was prepared in the same manner as in the photosensitive member preparation example 1 except that the tri- or higher functional radical polymerizable compound in the surface protective layer coating solution of the photosensitive member preparation example 1 was changed to the following. did.
・ Trifunctional or more radically polymerizable compounds [dipentaerythritol hexaacrylate,
(KAYARAD DPHA; manufactured by Nippon Kayaku Co., Ltd.)] ... 75 parts by mass

[Photoconductor Preparation Example 8]
<Production of electrophotographic photoreceptor>
In the surface protective layer coating solution of Photosensitive Member Preparation Example 1, the radical polymerizable compound having the charge transporting structure represented by Exemplary Compound 7 was changed to the following, and was the same as in Photosensitive Member Preparation Example 1. Thus, an electrophotographic photosensitive member 8 was produced.
-Radical polymerizable compound having a charge transporting structure (Exemplary Compound No. 38) ... 95 parts by mass

[Photoconductor Preparation Example 9]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 9 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was replaced with the following surface protection layer coating solution.

[Surface protective layer coating solution]
-Polyvinyl acetal resin [ESREC BX-1; manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 90 ° C., molecular weight 100,000, hydroxyl group content 33 mol%)] ... 5 parts by mass. Trifunctional or higher functional radical polymerizable compound [trimethylolpropane triacrylate,
(TMPTA; manufactured by Tokyo Chemical Industry Co., Ltd.)] ... 90 parts by mass-Radically polymerizable compound having a charge transporting structure (Exemplary Compound 7) ... 95 parts by mass-Photopolymerization initiator [1-hydroxy-cyclohexyl- Phenyl-ketone,
(Irgacure 184; manufactured by Ciba Specialty Chemicals)] ... 10 parts by mass Tetrahydrofuran ... 1,200 parts by mass

[Photoconductor Preparation Example 10]
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 10 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was replaced with the following surface protection layer coating solution.

[Surface protective layer coating solution]
-Polyvinyl acetal resin [ESREC BX-1: manufactured by Sekisui Chemical Co., Ltd.,
(Glass transition temperature 90 ° C., molecular weight 100,000, hydroxyl group content 33 mol%)] ... 45 parts by mass. Trifunctional or higher functional radical polymerizable compound [trimethylolpropane triacrylate,
(TMPTA; manufactured by Tokyo Chemical Industry Co., Ltd.)] 45 parts by mass-Radical polymerizable compound having a charge transporting structure (Exemplary Compound 7) 95 parts by mass-Photopolymerization initiator [1-hydroxy-cyclohexyl- Phenyl-ketone,
(Irgacure 184; manufactured by Ciba Specialty Chemicals)] ... 10 parts by mass Tetrahydrofuran ... 1,200 parts by mass

[Photoreceptor Preparation Example 11]
<Production of electrophotographic photoreceptor>
In the surface protective layer coating solution of Photoreceptor Preparation Example 1, the same procedure as in Photoreceptor Preparation Example 1 was performed except that the polyvinyl acetal compound was replaced with a radical polymerizable compound represented by the following structural formula (4). A photoconductor 11 was produced.

[Photoconductor Preparation Example 12]
<Production of electrophotographic photoreceptor>
In the surface protective layer coating solution of Photoreceptor Preparation Example 1, the same procedure as in Photoreceptor Preparation Example 1 was performed except that the polyvinyl acetal compound was replaced with a radical polymerizable compound represented by the following structural formula (5). A photoconductor 12 was prepared.

[Photoconductor Preparation Example 13]
<Production of electrophotographic photoreceptor>
In the surface protective layer coating solution of Photoreceptor Preparation Example 1, the same procedure as in Photoreceptor Preparation Example 1 was performed except that the polyvinyl acetal compound was replaced with a radical polymerizable compound represented by the following structural formula (6). A photoconductor 13 was prepared.

[Photoconductor Preparation Example 14]
<Production of electrophotographic photoreceptor>
The electrophotographic photosensitive member 14 was prepared in the same manner as in the photosensitive member manufacturing example 1, except that the trifunctional or higher functional radical polymerizable compound in the surface protective layer coating solution of the photosensitive member manufacturing example 1 was changed to the following. did.
-Bifunctional radically polymerizable compound [bifunctional acrylate represented by the following structural formula (7),
(KAYARAD NPGDA; made by Nippon Kayaku)] ... 75 parts by mass

(Examples 1-10, Comparative Examples 1-4)
Next, each manufactured electrophotographic photosensitive member is mounted on a process cartridge, and the manufactured electrostatic charge image developing toner 1 is used to continuously produce a total of 500,000 actual machines using imago MPC4500 manufactured by Ricoh Co., Ltd. A paper passing test was performed, and the wear amount measurement, the in-machine potential measurement, and the image evaluation were performed as follows.
The photoreceptors used in Examples 1 to 10 and Comparative Examples 1 to 4 and the main components of the surface protective layer are summarized in Table 3 below. The evaluation results are shown in Table 4 below.

<Abrasion amount>
Before and after passing 500,000 sheets, the film thickness of the electrophotographic photosensitive member was measured using an eddy current film thickness meter (Fisherscope MMS, manufactured by Fisher Instruments Co., Ltd.). The difference was defined as the amount of wear.

<In-flight potential>
After passing 500,000 sheets, a surface potential meter was set on imgio MPC4500 manufactured by Ricoh Co., Ltd. used in the actual machine passing test, and the surface potential when one A4 size image of the entire white pattern and the entire black pattern was output. Were measured, and dark part potential and bright part potential were determined.

<Image evaluation>
After passing 500,000 sheets, output two A3 size images of full white pattern, full black pattern, and full halftone pattern using imgio MPC4500 manufactured by Ricoh Co., Ltd. The presence or absence was confirmed.

(Examples 11 to 13, Comparative Example 5)
Next, the electrophotographic photosensitive member 1 is mounted on a process cartridge, and the produced electrostatic charge image developing toners 2 to 5 are used. A paper passing test was performed, and the wear amount measurement, the in-machine potential measurement, and the image evaluation were performed as follows. The results are shown in Table 5 below.

From the results of Tables 4 and 5, the surface protective layer was obtained by reacting a radical polymerizable monomer having a trifunctional or higher functionality with a radical polymerizable compound having a charge transporting structure (cured product) and acetalization reaction of polyvinyl alcohol and aldehyde. In the image forming apparatuses of Examples 1 to 13 including the electrophotographic photosensitive member having the constitution of the present invention containing the synthesized polyvinyl acetal compound, silica fine particles hydrophobized on the surfaces of the toner base particles are attached. Even when a large number of sheets are developed using the toner as described above, there is no image defect (streak-like defect), or there is no problem even if it exists.
As described above, a toner in which silica fine particles hydrophobized on the surface of toner base particles containing an electrophotographic photosensitive member, charging means, exposure means, and at least a binder resin and a colorant are attached. The surface protective layer of the electrophotographic photosensitive member provided in the image forming apparatus having a developing unit that develops and forms a visible image by using, a transfer unit, and a fixing unit is a radically polymerizable monomer having at least three functional groups. A structure containing a reaction product (hereinafter sometimes referred to as “cured product”) with a radical polymerizable compound having a charge transporting structure and a polyvinyl acetal compound synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde. As a result, high wear resistance and high releasability can be obtained, and even when the toner is used, abnormal images and the like due to silica adhesion can be generated for a long time. It is possible to suppress me.
That is, the image forming apparatus of the present invention can output high-quality images stably over a long period of time. For example, a full color using a laser printer, a direct digital plate making machine, a direct or indirect electrophotographic multicolor image developing system, and the like. It can be widely used for copying machines, full color laser printers, CRT printers, LED printers, liquid crystal printers, laser plate making, full color plain paper fax machines, and the like.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charging roller 5 Image exposure part 6 Developing unit 8 Registration roller 9 Recording medium 10 Transfer charger 15 Cleaning blade 101 Electrophotographic photosensitive body (photosensitive drum)
102 Charging means (charging device)
103 Exposure means (exposure)
104 Developing means (developing device)
105 Recording medium 106 Transfer means (transfer device)
107 Cleaning means (cleaning blade)
DESCRIPTION OF SYMBOLS 201 Support body 202 Photosensitive layer 203 Surface protective layer 204 Charge generation layer 205 Charge transport layer

JP 2003-316057 A JP 2001-272807 A Japanese Patent No. 4208367 Japanese Patent No. 4160512 JP-A-6-95413 Japanese Patent No. 3938209 Japanese Patent No. 4214655

Claims (5)

An electrophotographic photosensitive member, a charging unit for charging the surface of the electrophotographic photosensitive member, an exposure unit for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and at least the electrostatic latent image are formed. Development means for forming a visible image by developing using toner in which silica fine particles hydrophobized to the surface of toner base particles containing a resin and a colorant are attached, and recording the visible image on a recording medium An image forming apparatus comprising: a transfer unit that transfers to a recording medium; and a fixing unit that fixes the transferred image transferred to the recording medium.
The electrophotographic photoreceptor comprises at least a photosensitive layer and a surface protective layer on a support, and the surface protective layer comprises a radical polymerizable monomer having a trifunctional or higher functional group and a radical polymerizable compound having a charge transporting structure. Containing a reaction product and a polyvinyl acetal compound synthesized by acetalization reaction of polyvinyl alcohol and aldehyde ,
The polyvinyl acetal compound is represented by the following general formula (I):
The number average molecular weight of the said polyvinyl acetal compound is 100,000 or more, and the composition ratio n of the repeating unit containing a hydroxyl group is 25 mol% or more, The image forming apparatus characterized by the above-mentioned .

[In formula (I), R ₁ and R ₂ represent different alkyl groups having 1 to 3 carbon atoms. k, l, m and n represent the composition ratio (mol%), and one of k or l may be 0, but the sum of k and l, m and n both have a value greater than 0. The sum of k, l, m, and n is 100. ] The image forming apparatus according to claim 1 , wherein the polyvinyl acetal compound has a glass transition temperature of 70 ° C. or higher. The content of the polyvinyl acetal compound, wherein 3 to functional or more radical polymerizable monomer 100 parts by weight, the image forming apparatus according to claim 1 or 2, characterized in that 5 to 100 parts by weight. The image forming apparatus according to any one of claims 1 to 3, wherein the average primary particle diameter of the hydrophobized silica fine particles are 100 to 200 nm. At least an electrophotographic photosensitive member, a charging means, developing means, transfer means, and at least one means selected from the cleaning means and charge eliminating means, the image forming apparatus main body according to any one of claims 1 to 4 A process cartridge which is detachable.

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