JP2019095674A - Electrophotographic process cartridge, and electrophotographic device - Google Patents

Abstract

An electrophotographic process cartridge and an electrophotographic apparatus in which image unevenness due to a ghost phenomenon and insufficient charging are suppressed are provided. In an electrophotographic process cartridge having a charging member and an electrophotographic photosensitive member contact-charged by the charging member, the charging member is a charging member having a conductive support and a conductive surface layer. The surface layer includes insulating hollow particles having a specific shell thickness and hollow part diameter and a binder, the hollow particles are held by the binder, and the hollow particles are exposed to the surface layer. The electrophotographic photosensitive member having a surface layer containing a polycarbonate resin or a polyester resin having a branched structure having a high charge mobility and a specific charge mobility. An electrophotographic process cartridge characterized by. [Selection] Figure 1

Description

  The present invention relates to an electrophotographic process cartridge and an electrophotographic apparatus.

  In the electrophotographic process, in recent years, demands for higher recording speed and higher image quality are increasing. Correspondingly, the electrophotographic photosensitive member is desired to further improve the response of the potential drop due to the exposure, and further to improve the cause of lowering the image quality such as the ghost phenomenon. As a method of enhancing the responsiveness of an electrophotographic photosensitive member, a method of using a charge transport material (CTM) having high charge mobility for a charge transport layer is known (Patent Document 1).

JP 2008-74714 A

  However, in the study of the present inventors, while an electrophotographic photosensitive member using a charge transport material having a high charge mobility described in Patent Document 1 described above for the charge transport layer is improving the ghost phenomenon, When the responsiveness of the potential drop due to exposure is high, the potential difference charged in the charging step is increased, so that insufficient charging may occur and image unevenness may occur.

  One aspect of the present invention is directed to the provision of an electrophotographic process cartridge and an electrophotographic apparatus in which image unevenness due to ghosting and insufficient charging is suppressed.

（一般式（Ｉ）において、Ｘ^１は、単結合、酸素原子、２価のアルキリデン基又は２価のシクロアルキリデン基を表す。Ｒ^１１〜Ｒ^１８は、それぞれ独立に水素原子又はアルキル基を表す。）

（一般式（ＩＩ）において、Ｘ^２は２価の基を示す。）

（一般式（ＩＩＩ）において、Ｘ^３は、単結合、酸素原子、２価のアルキリデン基又は２価のシクロアルキリデン基を表す。Ｒ^３１〜Ｒ^３８は、それぞれ独立に水素原子又はアルキル基を表す。）。 According to one aspect of the invention:
An electrophotographic process cartridge detachably configured to a main body of an electrophotographic apparatus, comprising: a charging member; and an electrophotographic photosensitive member contact-charged by the charging member,
The charging member has a conductive support and a conductive surface layer, and the surface of the surface layer includes insulating hollow particles and a binder, and the binder holds the hollow particles, and the hollow is The particles form convex portions exposed on the surface of the surface layer, the average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, and the average hollow part diameter of the hollow particles is 7 μm or more It is a charging member characterized in that it is 100 μm or less, and the electrophotographic photosensitive member is an electrophotographic photosensitive member having a surface layer containing a charge transporting substance and a polycarbonate resin or a polyester resin,
The polycarbonate resin has a structure represented by the general formula (I),
An electrophotographic process cartridge, which is an electrophotographic photosensitive member, is characterized in that the polyester resin has a structure represented by the general formula (II) and a structure represented by the general formula (III):

(In the general formula (I), X ¹ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{11 to} R ¹⁸ each independently represent a hydrogen atom or an alkyl group .)

(In the general formula (II), X ² represents a divalent group.)

(In the general formula (III), X ³ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{31 to} R ³⁸ each independently represent a hydrogen atom or an alkyl group. ).

（一般式（Ｉ−１）において、Ｒ^１１１は、水素原子、メチル基、エチル基、フェニル基を表す。Ｒ^１１２、Ｒ^１１３は、それぞれ独立に炭素数１〜４のアルキル基を表す。Ｒ^１１４〜Ｒ^１１７は、それぞれ独立に水素原子又はメチル基を表す。ｍは、括弧内の繰り返し数を示し、０〜３の整数である。）

（一般式（ＩＩ）において、Ｘ^２は２価の基を示す。）

（一般式（ＩＩＩ−１）において、Ｒ^３１１は、水素原子、メチル基、エチル基、フェニル基を表す。Ｒ^３１２、Ｒ^３１３は、それぞれ独立に炭素数１〜４のアルキル基を表す。Ｒ^３１４〜Ｒ^３１７は、それぞれ独立に水素原子又はメチル基を表す。ｎは、括弧内の繰り返し数を示し、０〜３の整数である。）。 Furthermore, according to another aspect of the present invention,
An electrophotographic apparatus comprising a charging member and an electrophotographic photosensitive member contact-charged by the charging member, comprising:
The charging member has a conductive support and a conductive surface layer, and the surface of the surface layer includes insulating hollow particles and a binder, and the binder holds the hollow particles, and the hollow is The particles form convex portions exposed on the surface of the surface layer, the average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, and the average hollow part diameter of the hollow particles is 7 μm or more It is a charging member characterized in that it is 100 μm or less, and the electrophotographic photosensitive member is an electrophotographic photosensitive member having a surface layer containing a charge transporting substance and a polycarbonate resin or a polyester resin,
The polycarbonate resin has a structure represented by the general formula (I-1),
An electrophotographic apparatus is provided, which is an electrophotographic photosensitive member characterized in that the polyester resin has a structure represented by the general formula (II) and a structure represented by the general formula (III-1):

(In the general formula (I-1), R ¹¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ¹¹² and R ¹¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{114 to} R ¹¹⁷ each independently represent a hydrogen atom or a methyl group, m represents the number of repetitions in parentheses, and is an integer of 0 to 3)

(In the general formula (II), X ² represents a divalent group.)

(In the general formula (III-1), R ³¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ³¹² and R ³¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{314 to} R ³¹⁷ each independently represent a hydrogen atom or a methyl group, n represents the number of repetitions in parentheses and is an integer of 0 to 3).

  The present invention provides an electrophotographic process cartridge and an electrophotographic apparatus in which image unevenness caused by ghosting and insufficient charging is suppressed.

It is a schematic diagram for demonstrating discharge of the insulating hollow particle which concerns on 1 aspect of this invention. FIG. 2 is a schematic cross-sectional view showing a configuration example of a charging member according to an aspect of the present invention. It is a schematic block diagram of an example of a cross head extrusion molding machine. It is a figure which shows the image for ghost phenomenon evaluation used in the Example. FIG. 1 is a schematic configuration diagram of an example of an electrophotographic apparatus.

（一般式（Ｉ）において、Ｘ^１は、単結合、酸素原子、２価のアルキリデン基又は２価のシクロアルキリデン基を表す。Ｒ^１１〜Ｒ^１８は、それぞれ独立に水素原子又はアルキル基を表す。）

（一般式（ＩＩ）において、Ｘ^２は２価の基を示す。）

（一般式（ＩＩＩ）において、Ｘ^３は、単結合、酸素原子、２価のアルキリデン基又は２価のシクロアルキリデン基を表す。Ｒ^３１〜Ｒ^３８は、それぞれ独立に水素原子又はアルキル基を表す。）
一般式（Ｉ）において、Ｘ^１が、２価のアルキリデン基である場合、置換基としてフェニル基を有してもよい。また、一般式（ＩＩＩ）において、Ｘ^３が、２価のアルキリデン基である場合、置換基としてフェニル基を有してもよい。 An electrophotographic process cartridge according to an aspect of the present invention includes a charging member and an electrophotographic photosensitive member contact-charged by the charging member.
The charging member has a conductive support and a conductive surface layer, and the surface of the surface layer includes insulating hollow particles and a binder, and the binder holds the hollow particles, and the hollow is The particles form convex portions exposed on the surface of the surface layer, the average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, and the average hollow part diameter of the hollow particles is 7 μm or more 100 μm or less.
Further, the electrophotographic photosensitive member has a surface layer containing a charge transporting substance and a polycarbonate resin or a polyester resin, and the polycarbonate resin has a structure represented by the general formula (I),
The polyester resin has a structure represented by the general formula (II) and a structure represented by the general formula (III).

(In the general formula (I), X ¹ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{11 to} R ¹⁸ each independently represent a hydrogen atom or an alkyl group .)

(In the general formula (II), X ² represents a divalent group.)

(In the general formula (III), X ³ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{31 to} R ³⁸ each independently represent a hydrogen atom or an alkyl group. .)
When X ¹ in General Formula (I) is a divalent alkylidene group, it may have a phenyl group as a substituent. In addition, in the general formula (III), when X ³ is a divalent alkylidene group, it may have a phenyl group as a substituent.

（一般式（Ｉ−１）において、Ｒ^１１１は、水素原子、メチル基、エチル基、フェニル基を表す。Ｒ^１１２、Ｒ^１１３は、それぞれ独立に炭素数１〜４のアルキル基を表す。Ｒ^１１４〜Ｒ^１１７は、それぞれ独立に水素原子又はメチル基を表す。ｍは、括弧内の繰り返し数を示し、０〜３の整数である。）

（一般式（ＩＩ）において、Ｘ^２は２価の基を示す。）

（一般式（ＩＩＩ−１）において、Ｒ^３１１は、水素原子、メチル基、エチル基、フェニル基を表す。Ｒ^３１２、Ｒ^３１３は、それぞれ独立に炭素数１〜４のアルキル基を表す。Ｒ^３１４〜Ｒ^３１７は、それぞれ独立に水素原子又はメチル基を表す。ｎは、括弧内の繰り返し数を示し、０〜３の整数である。） Furthermore, an electrophotographic process cartridge according to another aspect of the present invention has a charging member and an electrophotographic photosensitive member contact-charged by the charging member.
The charging member has a conductive support and a conductive surface layer, and the surface of the surface layer includes insulating hollow particles and a binder, and the binder holds the hollow particles, and the hollow is The particles form convex portions exposed on the surface of the surface layer, the average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, and the average hollow part diameter of the hollow particles is 7 μm or more 100 μm or less.
In addition, the electrophotographic photosensitive member has a surface layer containing a charge transport substance and a polycarbonate resin or a polyester resin,
The polycarbonate resin has a structure represented by the general formula (I-1),
The polyester resin has a structure represented by the general formula (II) and a structure represented by the general formula (III-1).

(In the general formula (I-1), R ¹¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ¹¹² and R ¹¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{114 to} R ¹¹⁷ each independently represent a hydrogen atom or a methyl group, m represents the number of repetitions in parentheses, and is an integer of 0 to 3)

(In the general formula (II), X ² represents a divalent group.)

(In the general formula (III-1), R ³¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ³¹² and R ³¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{314 to} R ³¹⁷ each independently represent a hydrogen atom or a methyl group, n represents the number of repetitions in parentheses, and is an integer of 0 to 3).

  Furthermore, the present invention relates to an electrophotographic apparatus having the above-described electrophotographic process cartridge.

The inventors of the present invention have estimated as follows the mechanism that exerts the effect of suppressing the image unevenness caused by the ghost phenomenon and the insufficient charging in the electrophotographic process cartridge according to each aspect of the present invention.
First, in the electrophotographic photosensitive member, by using a resin structure in which a bulky branched chain structure as represented by the general formulas (I-1) and (III-1) is introduced in the resin chain, it relies on the charge transport material. Therefore, the charge mobility can be improved. In addition, regarding suppression of the ghost phenomenon, it is conceivable that not only charge mobility is improved but also charge retention is suppressed. It is presumed that this is because the charge mobility is improved not by the charge transport substance but by the resin structure.

  In order to take advantage of the performance of the electrophotographic photosensitive member capable of sufficiently lowering the potential by exposure, as the charging member, a charging member capable of discharging an amount of discharge charge higher than that of the prior art is required. That is, since the potential drop by exposure is large, the potential before charging of the electrophotographic photosensitive member is lowered, and in order to obtain a desired potential after charging, a charging member capable of discharging a large amount of discharge charge is required. . In order to realize that, a specific hollow particle exposed charging member is used. The reason why the hollow particles exhibit a high discharge charge amount is estimated as follows.

  FIG. 1 is a schematic view showing a cross section of a discharge region in a gap in the vicinity of the nip between an electrophotographic photosensitive member and a charging member. A discharge occurs between the surface 11 of the electrophotographic photosensitive member and the hollow particles 12 and the binder portion 13 on the surface of the charging member. This figure shows the case where the electrophotographic photosensitive member is grounded and the charging member is applied with a voltage to the negative electrode.

  When a discharge occurs between the exposed convex portion of the hollow particle and the electrophotographic photosensitive member, the shell of the exposed hollow particle is charged and positively charged up. Therefore, the potential difference between the upper and lower portions inside the hollow particles is increased, and the discharge 14 occurs inside the hollow particles. At this time, the shell of the hollow particles exposed on the surface is charged 15 to negative polarity by the discharge 14 inside the hollow particles. Since the exposed shell is insulating, the potential is higher than that of the conductive binder portion 13. Therefore, electric field concentration occurs and discharge 16 with a high discharge charge amount occurs. Therefore, the charging member in which the hollow particles according to the present invention exist on the surface exhibits a discharge charge amount higher than that of the conventional charging member, and an image caused by insufficient discharge even in the case of an electrophotographic photosensitive member having high charge mobility. It is assumed that unevenness can be suppressed.

  On the other hand, when the hollow particles are contained in the conductive binder, the charge moves freely in the surface direction of the charging member. Therefore, the surface of the charging member is equipotential, and no electric field concentration occurs, so that the effect as in the present invention can not be expected.

  Further, the present invention assumes a general conductive binder as the charging member. This is because when the binder is insulating, a sufficient amount of discharge charge can not be originally obtained.

  Hereinafter, preferred embodiments of the present invention will be described. However, the present invention is not limited to this embodiment.

<Electrophotographic apparatus>
FIG. 5 shows an example of an electrophotographic apparatus (electrophotographic image forming apparatus) according to the present invention. An electrophotographic photosensitive member (hereinafter sometimes referred to as "photosensitive member") 51 includes a conductive support 51b having conductivity such as aluminum and a photosensitive layer 51a formed on the conductive support 51b as a basic constituent layer. Drum-shaped electrophotographic photosensitive member. The photosensitive member 51 is rotationally driven in the clockwise direction on the sheet of the drawing at a predetermined peripheral speed around the shaft 51c.

  The charging device includes a charging member 30, a power supply 53, and a rubbing power supply (not shown), and the charging device charges the surface of the photosensitive layer. The charging member 30 is a charging roller composed of a core metal 31 and a conductive elastic layer 32 provided on the outer periphery thereof, and both ends of the core metal 31 are pressed against the electrophotographic photosensitive member 51 by pressing means (not shown). ing. Then, when the electrophotographic photosensitive member 51 is rotated by a driving unit (not shown), it is driven to rotate accordingly. By applying a predetermined direct current (DC) bias voltage to the core metal 31 from the power source 53, the electrophotographic photosensitive member 51 is charged to a predetermined polarity and a predetermined potential. If the alternating current (AC) bias and the direct current bias are superimposed and applied, the discharge is less likely to occur. On the other hand, the problem is that charging noise is generated and the cost is high. In the charging member of the present invention, a direct current bias is preferable because the direct current bias can be used without an insufficient discharge.

  The electrophotographic photosensitive member 51 whose peripheral surface is charged by the charging member is then subjected to exposure (laser beam scanning exposure, slit exposure of an original image, etc.) of the target image information by the exposure device 54, and target image information is formed on the peripheral surface. An electrostatic latent image corresponding to is formed.

  The electrostatic latent image is sequentially visualized as a toner image by the developing device 55. Then, the toner image is sequentially transferred to the transfer material 57 by the transfer unit 56. The transfer material is conveyed from the sheet feeding unit (not shown) in synchronization with the rotation of the electrophotographic photosensitive member 51 and conveyed to the transfer portion between the electrophotographic photosensitive member 51 and the transfer unit 56 at an appropriate timing. The transfer means 56 of this embodiment is a transfer roller, and by charging the reverse polarity of the toner from the back of the transfer material 57, the toner image on the electrophotographic photosensitive member 51 side is transferred to the transfer material 57. The transfer material 57 which has received the transfer of the toner image on the surface thereof is separated from the electrophotographic photosensitive member 51, conveyed to a fixing unit (not shown), subjected to image fixing, and outputted as an image forming material.

  The peripheral surface of the electrophotographic photosensitive member 51 after transfer is subjected to removal of adhering contaminants such as transfer residual toner by the cleaning device 58, and is cleaned and converted, and is repeatedly subjected to image formation.

<Electrophotographic process cartridge>
An electrophotographic process cartridge configured to be removable from the main body of the electrophotographic apparatus by integrating the electrophotographic photosensitive member 51, the charging device (including the charging member 30), the exposure device 54 and the developing device 55, and further the cleaning device 58. Can be formed.

<Charging member>
An example of the charging member is shown in FIG. The charging member shown here is a charging roller, and is comprised of a cored bar 21 as a conductive support and a conductive elastic layer 22 provided on the outer periphery thereof. Another conductive elastic layer may be disposed between the conductive elastic layer 22 and the core metal 21. The charging member can be used as a charging member of the electrophotographic apparatus shown in FIG.

(Conductive support)
The conductive support may be any conductive support that can support a surface layer or the like and can maintain its strength as a charging member, typically as a charging roller. The conductivity of the conductive support can be set appropriately, for example, can be appropriately set in a known range as the conductivity of the conductive support of the charging member for electrophotography.

(Conductive elastic layer as surface layer)
The conductive elastic layer as the surface layer can be composed of a binder and insulating hollow particles.

  As the binder, a material exhibiting rubber elasticity can be used. Specific rubber materials that can be used for the binder include, for example, the following polymers. Natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene-diene terpolymer rubber (EPDM), epichlorohydrin homopolymer ( CHC), epichlorohydrin-ethylene oxide copolymer (CHR), epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (CHR-AGE), acrylonitrile-butadiene copolymer (NBR), acrylonitrile-butadiene copolymer Thermosetting rubber materials in which a crosslinking agent is mixed with raw material rubber such as hydrogenated substance (H-NBR), chloroprene rubber (CR), acrylic rubber (ACM, ANM), polyolefin thermoplastic elastomer, polystyrene thermoplastic Elastomer Polyester thermoplastic elastomers, polyurethane thermoplastic elastomers, polyamide thermoplastic elastomers, thermoplastic elastomers and polyvinyl chloride thermoplastic elastomer. Furthermore, the mixture which blended these polymers may be sufficient. Among them, acrylonitrile butadiene rubber is preferable because it is excellent in processability and most suitable for extrusion.

  In the surface layer, carbon black as conductive particles is blended as needed. The blending amount of carbon black can be adjusted and blended so that the electric resistance of the surface layer becomes a desired value. The conductivity of the surface layer can be set appropriately, for example, can be appropriately set in a known range as the conductivity of the surface layer of the charging member for electrophotography.

  A preferable blending amount of carbon black is 20 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the binder polymer. By setting the compounding amount of carbon black to 20 parts by mass or more, lowering of the hardness of the surface layer can be suppressed, and appropriate hardness can be obtained. Moreover, if the compounding quantity of carbon black is 70 mass parts or less, high hardness-ization of a surface layer can be suppressed and appropriate hardness can be obtained. By suppressing the increase in hardness of the surface layer, the contact state between the surface layer and the photosensitive member is improved, and dirt such as toner or paper dust adheres unevenly to the surface of the charging member during long-term use, resulting in image defects. Can be prevented.

  The type of carbon black to be blended is not particularly limited. Specific examples of carbon black that can be used are listed below. Gas furnace black, oil furnace black, thermal black, lamp black, acetylene black, ketjen black etc.

  Furthermore, in the composition to be the material of the surface layer, a filler, a processing aid, a crosslinking aid, a crosslinking accelerator, a crosslinking accelerator, a crosslinking retarder, which is generally used as a compounding agent for rubber if necessary. Softeners, plasticizers, or dispersants can be added. As a mixing method of these raw materials, a mixing method using a closed mixer such as a Banbury mixer or a pressure kneader, a mixing method using an open mixer such as an open roll, and the like can be exemplified.

  The average hollow part diameter of the insulating hollow particles is 7 μm to 100 μm, preferably 25 μm to 60 μm. The average hollow portion diameter is the diameter of a sphere corresponding to the volume of the hollow portion measured by the method described later. The discharge charge amount is weaker as the distance of the discharge gap is shorter. In addition, when the discharge gap is too wide, the discharge start voltage is not exceeded, so the discharge does not occur. Therefore, a proper hollow diameter is required. That is, if it is 7 μm or more and 100 μm or less, and further, 25 μm or more and 60 μm or less, the discharge in the hollow space is efficiently generated to efficiently charge the shell of the hollow particle.

  The average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, preferably 1.30 μm or more and 2.50 μm or less. When the average thickness is 0.05 μm or more, the exposed convex portions of the hollow particles due to wear and breakage of the shell can be sufficiently maintained even in long-term use. Further, by setting the average thickness of the shell of the hollow particle to 3.00 μm or less, the capacitance of the shell of the hollow particle is increased, and the charge moves from the inner side to the outer side of the shell to the surface of the electrophotographic photosensitive member. Promote the discharge of

<Method of manufacturing charging member>
As an example of the method for producing the charging member of the present invention, an effective method will be described particularly from the viewpoint of simplicity of the production method.
The manufacturing method is a method of manufacturing a charging member, in particular, a charging roller, which includes the following steps.
-A step of preparing an unvulcanized rubber composition containing a rubber material as a binder and thermally expanded microcapsule particles (unvulcanized rubber preparation step).
· After cross-head extrusion molding of an unvulcanized rubber composition on a conductive support, the resulting molded product is heated and vulcanized to foam thermally expanded microcapsule particles and as a surface layer Forming a conductive elastic layer; In this step, the thermally expanded microcapsules are foamed to be the hollow particles of the present invention, and to be convex portions exposed to the surface layer.

Heretofore, as a method of manufacturing a charging member, a method of forming by molding and a method of polishing an extrusion-molded material have been known conventionally. However, in these manufacturing methods, the exposed convexes of the hollow particles are not formed.
Therefore, it is necessary to perform extrusion molding with high shape accuracy, and to mold the shape after extrusion so as to be a desired shape after vulcanization and foaming. The desired shape is a crown shape in which the outer diameter gradually decreases toward the longitudinal end of the charging roller, and is preferably an error within ± 10 μm with respect to the diameter of the ideal crown shape. Further, it is preferable that the degree of coaxiality of the charging roller in the longitudinal direction is small, and the distance of concentricity in every 30 mm in longitudinal direction is preferably within 10 μm.

(Unvulcanized rubber preparation process)
First, unvulcanized rubber containing a conductive rubber composition and thermally expandable microcapsule particles, which is a material constituting a surface layer, is prepared.
It is preferable to use thermally expanded microcapsule particles as a precursor of the insulating hollow particles. It is because the convex part derived from the insulating hollow particle exposed from the surface of the surface layer can be easily formed by using the thermally expanded microcapsule particle. Furthermore, by using thermally expanded microcapsule particles, it is possible to adjust the balance between foaming and vulcanization by controlling the heating method, and it is possible to control the shell thickness and the average hollow diameter of hollow particles. . Therefore, the relationship between the crosslinking initiation temperature (Tc) of the unvulcanized rubber composition and the foaming initiation temperature (Ts) of the thermally expanded microcapsule particles is preferably such that the crosslinking initiation temperature is higher than the foaming initiation temperature. The reason will be described later in the vulcanization / foaming process.

· Crosslinking start temperature (Tc)
The crosslinking start temperature described here can be determined as follows using a Mooney viscometer (trade name: SMT300RT manufactured by Shimadzu Corporation) in accordance with JIS-K6300-1: 2013. The scorch time of the rubber composition is determined at each temperature in steps of 5 ° C. from 130 ° C. to 160 ° C. The scorch time is the time for the Mooney viscosity (ML1 + 4) measured using the L-shaped rotor to rise 5 points from the minimum value Vm. The relationship between the obtained scorch time and the measured temperature is logarithmically approximated, and from the approximate curve, the temperature at which the scorch time is 10 minutes is determined, and this is taken as the crosslinking initiation temperature.

· Foaming start temperature (Ts)
The foaming start temperature can be determined as follows using a thermomechanical analyzer (TMA) (trade name: TMA 2940, manufactured by TA instruments). Measure the displacement of the measurement terminal in the vertical direction while heating the thermally expanded microcapsule particles from 80 ° C to 220 ° C at a heating rate of 5 ° C / min, and the temperature at which the displacement starts to rise ) As the foaming start temperature. At this time, 25 μg of a sample (thermally expanded microcapsule particles) is placed in an aluminum container having a diameter of 7 mm and a depth of 1 mm, and measurement is carried out with a force of 0.1 N applied from above.
The content of the thermally expanded microcapsule particles in the unvulcanized rubber composition is preferably 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the raw material rubber. Within this range, a suitable amount of insulating hollow particles can be present on the surface of the charging member.
The vulcanizing agent can be appropriately selected in consideration of the rubber material to be used.
The thermally expanded microcapsule particles extruded together with the binder are not so exposed on the extrusion surface, but expand in the vulcanization / foaming step to become hollow particles and become exposed convex portions. When the viscosity of the binder is too low, it is easy to expand and therefore prevents the microcapsules from being exposed, while when it is too high, the thermally expanded microcapsule particles prevent the binder from being displaced and exposed to the surface. In fact, the viscosity of the binder at the moment of foaming is important, but the Mooney viscosity ML (1 + 4) of the binder is preferably 20 to 70 as 100 ° C.

(Extrusion molding process)
This unvulcanized rubber composition can be used to form a roller for use as a charging member. Crosshead extrusion is preferred to expose the thermally expanded microcapsule particles to the surface of the molding.

  FIG. 3 is a schematic configuration view of the crosshead extruder 3. The crosshead extruder 3 is an apparatus for uniformly coating the cored bar 31 with the unvulcanized rubber composition 39 over the entire circumference thereof to produce an unvulcanized rubber roller 33 containing the cored bar 31 at the center. is there.

  A crosshead 34 into which the core metal 31 and the unvulcanized rubber composition 39 are fed into the crosshead extruder 3, a transport roller 35 into which the core metal 31 is fed into the crosshead 34, and an unvulcanized rubber into the crosshead 34 And a cylinder 36 for feeding the composition 39.

  The transport roller 35 feeds the plurality of core bars 31 into the crosshead 34 continuously in the axial direction. The cylinder 36 is internally provided with a screw 37, and the rotation of the screw 37 feeds the unvulcanized rubber composition 39 into the crosshead 34.

  When the core metal 31 is fed into the crosshead 34, the entire circumference is covered with the unvulcanized rubber composition 39 fed from the cylinder 36 into the crosshead. Then, the core metal 31 is delivered from the die 38 at the outlet of the crosshead 34 as an unvulcanized rubber roller 33 whose surface is coated with the unvulcanized rubber composition 39.

  At that time, in order to control the shell thickness and particle diameter of the insulating hollow particles, and to effectively form the convex portions exposed by the insulating hollow particles on the surface of the charging member, the expansion start temperature of the thermally expanded microcapsule particles It is preferable to extrude less than. The extrusion temperature is lower than the vulcanization temperature.

The unvulcanized rubber composition can be formed into a so-called crown shape in which the outer diameter (thickness) is larger at the central portion in the longitudinal direction of each cored bar 31 than at the end portion. Specifically, while keeping the extrusion discharge amount of the unvulcanized rubber composition constant, the crown shape is gradually changed so that the core feeding speed is high at the end and slowed at the center. Form. Thus, the unvulcanized rubber roller 33 is obtained.
Further, in the extrusion step, in order to promote the exposure of the hollow particles, it is preferable to make the diameter of the unvulcanized rubber roller smaller than the diameter of the die portion of the die. By narrowing forming, that is, forming while the unvulcanized rubber composition is stretched, a tear occurs at the interface between the binder and the thermally expandable microcapsule particle, and the thermally expanded microcapsule particle is exposed, so that the hollow after foaming is generated. The particles are also exposed and easily exposed to the surface.

(Vulcanization / foaming process)
Next, the unvulcanized rubber roller is heated and crosslinked to obtain a vulcanized rubber roller in which hollow particles are exposed on the surface. As a specific example of the method of heat treatment, heating with a hot air furnace by a gear oven, heating by far infrared rays, steam heating by a vulcanizer, and the like can be mentioned. Among them, hot furnace heating and far infrared heating are preferable because they are suitable for continuous production.

  The average hollow diameter of the hollow particles exposed on the surface of the vulcanized rubber roller and the average thickness of the shell are the boiling point of the contained volatile component of the thermally expanded microcapsule, the vulcanization temperature of the unvulcanized rubber composition, and the vulcanization and foaming steps. It can be controlled by temperature. That is, using the difference between the boiling point of the contained volatile component of the thermally expanded microcapsule and the vulcanization temperature of the unvulcanized rubber composition, the temperature of the vulcanization / foaming step is changed to adjust the balance between vulcanization and foaming. At the temperature of the vulcanization / foaming step where vulcanization is prioritized, the foaming of the thermally expanded microcapsules is suppressed by the binder hardened by the crosslinking, resulting in hollow particles having a small particle diameter and a large thickness. On the contrary, at the temperature of the vulcanization / foaming process where foaming is prioritized, foaming of the thermally expanded microcapsules precedes hardening of the binder by crosslinking, resulting in hollow particles having large particle size and thin wall thickness.

The temperature of the vulcanization / foaming step in which the above-mentioned vulcanization is prioritized is a temperature which is slightly lower than the boiling point of the inclusion volatile component of the thermally expanded microcapsule, and the scorch of the binder and the vulcanizing agent proceeds. In the relationship between the temperature of the vulcanization and foaming process, the crosslinking initiation temperature, and the foaming initiation temperature, the temperature of the vulcanization and foaming process is higher when the crosslinking initiation temperature is higher than the foaming initiation temperature and is further specified. By setting the temperature of the vulcanization / foaming process <foaming start temperature <crosslinking start temperature, the temperature at which vulcanization is prioritized over foaming is obtained. On the other hand, the temperature of the vulcanization / foaming step in which foaming is prioritized is a temperature higher than the boiling point of the contained volatile component of the thermally expanded microcapsule. This is because the effervescent reaction is sufficiently faster than the crosslinking reaction, and effervescence is completed quickly when the reaction temperature is reached. In the relationship between the temperature of the vulcanization and foaming process, the crosslinking initiation temperature, and the foaming initiation temperature, the temperature of the vulcanization and foaming process is higher when the crosslinking initiation temperature is higher than the foaming initiation temperature and is further specified. By setting the foaming start temperature <the crosslinking start temperature <the temperature of the vulcanization / foaming step, it becomes a temperature where foaming is prioritized over vulcanization.
Also, the larger the particle size of the thermally expanded microcapsule, the larger the particle size of the hollow particle after foaming.

  In the present invention, the vulcanization process may be divided into two or more steps. By performing secondary vulcanization after the above-described primary vulcanization, the purpose of completing the vulcanization and the purpose of adjusting the height of the exposed convex portion of the hollow particle can be achieved. The reason why the height of the convex portion can be adjusted is that the thermally expandable macrocapsule has a property of shrinking as heating is continued, thereby reducing the roughness.

  Both ends of the rubber composition after vulcanization / foaming are removed in another process later to obtain a vulcanized / foamed rubber roller. Therefore, in the obtained vulcanized / foamed rubber roller, both ends of the core metal are exposed.

  In the present invention, in order to simplify the production process, the conductive elastic layer is most preferably a single layer, that is, the conductive elastic layer as the surface layer is the only conductive elastic layer. And, as the thickness of the surface layer in this case, in order to secure the nip width with the photosensitive member, the range of 0.8 mm or more and 4.0 mm or less, in particular, 1.2 mm or more and 3.0 mm or less preferable.

(Thermal expansion microcapsule particle)
Thermally expandable microcapsule particles are materials that include an inclusion substance inside a shell, and expand the inclusion substance by applying heat to become hollow particles.

  When thermally expandable microcapsule particles are used as the hollow particles, a thermoplastic resin can be used as the shell. The following are mentioned as a thermoplastic resin. Acrylonitrile resin, vinyl chloride resin, vinylidene chloride resin, methacrylic acid resin, styrene resin, urethane resin, amide resin, methacrylonitrile resin, acrylic acid resin, acrylic acid ester resin, methacrylic acid ester resin. These thermoplastic resins can be used alone or in combination of two or more. Furthermore, a monomer to be a raw material of these thermoplastic resins may be copolymerized to form a copolymer. Among these, it is preferable to use a thermoplastic resin composed of at least one selected from an acrylonitrile resin, a vinylidene chloride resin, and a methacrylonitrile resin exhibiting low gas permeability and high resilience.

  As the inclusion substance of the thermally expandable microcapsule particles, those which expand into gas at a temperature equal to or lower than the softening point of the thermoplastic resin are preferable. Low boiling liquids such as propane, butene, normal butane, isobutane, normal pentane, isopentane and isopentene; high boiling liquids such as normal hexane, isohexane, normal heptane, normal octane, isooctane, normal decane and isodecane.

  The above-mentioned thermally expanded microcapsule particles can be produced by a known production method such as suspension polymerization, interfacial polymerization, interfacial sedimentation, in-liquid drying and the like. For example, in the case of suspension polymerization, a polymerizable monomer, a substance to be encapsulated in the above-mentioned thermally expanded microcapsule particles, and a polymerization initiator are mixed, and this mixture is used in an aqueous medium containing a surfactant and a dispersion stabilizer. And the suspension polymerization can be exemplified. In addition, the compound which has a reactive group which reacts with the functional group of a polymerizable monomer, and an organic filler can also be added.

  The following can be illustrated as a polymerizable monomer. Acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, vinylidene chloride, vinyl acetate; acrylic ester (methyl acrylate, ethyl Acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, isobornyl acrylate, cyclohexyl acrylate, benzyl acrylate; methacrylic acid esters (methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, Isobornyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate); styrenic monomerア ク リ ル, acrylamide, substituted acrylamide, methacrylamide, substituted methacrylamide, butadiene, ε-caprolactam, polyether, isocyanate. These polymerizable monomers can be used alone or in combination of two or more.

  As the polymerization initiator, an initiator soluble in the polymerizable monomer is preferable, and known peroxide initiators and azo initiators can be used. Of these, azo initiators are preferred. Examples of azo initiators are listed below. 2,2'-azobisisobutyronitrile, 1,1'-azobiscyclohexane 1-carbonitrile, 2,2'-azobis-4-methoxy-2,4-dimethyl valeronitrile. Among these, 2,2'-azobisisobutyronitrile is preferable. For example, dicumyl peroxide can be used as the peroxide initiator. When using a polymerization initiator, 0.01-5 mass parts is preferable with respect to 100 weight parts of polymerizable monomers.

  As surfactants, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and polymer type dispersants can be used. The amount of surfactant used is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  The following may be mentioned as dispersion stabilizers. Organic fine particles (polystyrene fine particles, polymethyl methacrylate fine particles, polyacrylic acid fine particles, polyepoxide fine particles etc.), silica (such as colloidal silica), calcium carbonate, calcium phosphate, aluminum hydroxide, barium carbonate, magnesium hydroxide etc. The use amount of the dispersion stabilizer is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Suspension polymerization is preferably carried out in a sealed manner using a pressure resistant vessel. In addition, the raw material for polymerization may be suspended by a disperser or the like, and then transferred into the pressure resistant container for suspension polymerization, or may be suspended in the pressure resistant container. The polymerization temperature is preferably 50 ° C to 120 ° C. The polymerization may be carried out at atmospheric pressure, but it is carried out under pressure (for example, under a pressure of 0.1 to 1 MPa added to the atmospheric pressure) so as not to vaporize the substance to be encapsulated in the thermally expanded microcapsule particles. Is preferred. After completion of the polymerization, solid-liquid separation and washing may be performed by centrifugation or filtration. In the case of solid-liquid separation or washing, drying or grinding (to make aggregated particles into primary particles) may be performed at a temperature lower than the softening temperature of the resin constituting the thermally expanded microcapsule particles. Drying and grinding can be carried out by known methods, and flash dryers, normal wind dryers and Nauta mixers can be used. Drying and grinding can also be carried out simultaneously by means of a grinding dryer. Surfactants and dispersion stabilizers can be removed by repeated washing and filtration after production.

  The shape of the insulating hollow particle is not particularly limited, and examples thereof include a spherical shape, an indeterminate shape, and an elliptical shape.

(Measurement of insulation of insulating hollow particles)
According to the present invention, since the shell of the hollow particle forming the exposed convex portion is charged by the discharge inside the hollow particle, the electric resistance needs to be insulating to some extent. The insulating hollow particles may have a volume resistance of 10 ¹⁰ Ω cm or more. The volume resistance of the hollow particles can be pelletized by pressurizing the hollow particles, and the volume resistance of the pellets can be determined as the volume resistance of the pellets as measured by a powder resistance measuring device. As a powder resistance measuring device, a powder resistance measuring system MCP-PD 51 type (trade name, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) can be used. In order to pelletize, hollow particles to be measured are placed in a 20 mm diameter cylindrical chamber of a powder resistance measuring device. The filling amount is such that the thickness of the pellet when pressurized at 20 kN is 3 to 5 mm. The measurement is performed at an applied voltage of 90 V and a load of 4 kN in an environment of 23 ° C./50% RH (relative humidity).
Under control of these thermally expanded microcapsule particles, unvulcanized rubber preparation step, extrusion molding step, vulcanization / foaming step, the average hollow part diameter of the hollow particles is 7 μm to 100 μm, and the average thickness of the shell is 0. It can be adjusted to not less than 05 μm and 3.00 μm.

<Electrophotographic photosensitive member>
The electrophotographic photosensitive member of the present invention has a surface layer containing a charge transport material and a polycarbonate resin or a polyester resin. The photosensitive layer of the electrophotographic photosensitive member is mainly classified into (1) laminated type photosensitive layer and (2) single layer type photosensitive layer. (1) The laminate type photosensitive layer has a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance. (2) The single-layer type photosensitive layer has a photosensitive layer containing both the charge generating substance and the charge transporting substance. In the present invention, (1) in the case of the laminated photosensitive layer, the surface layer containing the charge transport substance is the charge transport layer, and (2) in the case of the single layer photosensitive layer, the surface layer containing the charge transport substance Is the photosensitive layer.

  As a method of producing an electrophotographic photosensitive member, there may be mentioned a method of preparing a coating solution for each layer to be described later on a support, applying the solution in the order of desired layers, and drying it. At this time, as a coating method of the coating liquid, a dip coating method, a spray coating method, a curtain coating method, a spin coating method and the like can be mentioned. Among these, the dip coating method is preferable from the viewpoint of efficiency and productivity.

Hereinafter, the support and each layer will be described.
<Support>
In the present invention, the electrophotographic photosensitive member has a support. In the present invention, the support is preferably a conductive support having conductivity. Moreover, as a shape of a support body, cylindrical shape, belt shape, a sheet shape, etc. are mentioned. Among them, a cylindrical support is preferable. In addition, the surface of the support may be subjected to electrochemical treatment such as anodization, blast treatment, cutting treatment and the like.
As a material of a support body, metal, resin, glass etc. are preferable.
Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel and alloys thereof. Among them, an aluminum support using aluminum is preferable.
In addition, the resin or glass may be provided with conductivity by a process such as mixing or coating of a conductive material.

<Conductive layer>
In the present invention, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to conceal scratches and irregularities on the surface of the support and to control the reflection of light on the surface of the support.
The conductive layer preferably contains conductive particles and a resin.

Examples of the material of the conductive particles include metal oxides, metals, carbon black and the like.
Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide and the like. Examples of the metal include aluminum, nickel, iron, nichrome, copper, zinc, silver and the like.
Among these, it is preferable to use a metal oxide as the conductive particles, and in particular, it is more preferable to use titanium oxide, tin oxide, or zinc oxide.
When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof.
In addition, the conductive particles may have a laminated structure including core material particles and a coating layer that covers the particles. The core particles include titanium oxide, barium sulfate, zinc oxide and the like. The covering layer may, for example, be a metal oxide such as tin oxide.
When a metal oxide is used as the conductive particles, the volume average particle diameter is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin and the like.
In addition, the conductive layer may further contain a masking agent such as silicone oil, resin particles, titanium oxide and the like.

  The average film thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

  The conductive layer can be formed by preparing a coating solution for a conductive layer containing the above-described respective materials and a solvent, forming the coating film, and drying it. Examples of the solvent used for the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like. As a dispersion method for dispersing conductive particles in the coating liquid for conductive layer, a method using a paint shaker, a sand mill, a ball mill, or a liquid collision type high speed disperser can be mentioned.

<Subbing layer>
In the present invention, an undercoat layer may be provided on the support or the conductive layer. By providing the undercoat layer, the adhesion function between the layers can be enhanced and the charge injection blocking function can be imparted.
The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

  As resin, polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin And polyamide acid resin, polyimide resin, polyamide imide resin, cellulose resin and the like.

  As a polymerizable functional group which a monomer having a polymerizable functional group has, an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, A carboxylic anhydride group, a carbon-carbon double bond group, etc. are mentioned.

  The undercoat layer may further contain an electron transport material, a metal oxide, a metal, a conductive polymer, and the like for the purpose of enhancing the electrical properties. Among these, electron transport substances and metal oxides are preferably used.

  Electron transport materials include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, boron compounds and the like. .

  The undercoat layer may be formed as a cured film by copolymerizing with the above-described monomer having a polymerizable functional group, using an electron transport material having a polymerizable functional group as the electron transporting substance.

  Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, silicon dioxide and the like. Examples of the metal include gold, silver and aluminum.

The undercoat layer may further contain an additive.
The average film thickness of the undercoat layer is preferably 0.1 μm to 50 μm, more preferably 0.2 μm to 40 μm, and particularly preferably 0.3 μm to 30 μm.

  The undercoat layer can be formed by preparing a coating solution for undercoat layer containing the above-described materials and a solvent, forming the coating film, and drying and / or curing. Examples of the solvent used for the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

<Photosensitive layer>
The photosensitive layer of the electrophotographic photosensitive member is mainly classified into (1) laminated type photosensitive layer and (2) single layer type photosensitive layer. (1) The laminated photosensitive layer has a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. (2) The single-layer type photosensitive layer has a photosensitive layer containing both the charge generating substance and the charge transporting substance.

(1) Stacked Photosensitive Layer The stacked photosensitive layer has a charge generation layer and a charge transport layer.

(1-1) Charge Generating Layer The charge generating layer preferably contains a charge generating substance and a resin.

  Examples of the charge generating material include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferable. Among the phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments and hydroxygallium phthalocyanine pigments are preferable.

  The content of the charge generation material in the charge generation layer is preferably 40% by mass to 85% by mass, and more preferably 60% by mass to 80% by mass, with respect to the total mass of the charge generation layer. preferable.

  As resin, polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin And polyvinyl chloride resin. Among these, polyvinyl butyral resin is more preferable.

  The charge generation layer may further contain an additive such as an antioxidant and an ultraviolet light absorber. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds and the like can be mentioned.

  The average film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

  The charge generation layer can be formed by preparing a coating solution for charge generation layer containing the above-mentioned respective materials and a solvent, forming this coating film, and drying it. Examples of the solvent used for the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

(1-2) Charge Transport Layer The charge transport layer contains a charge transport substance and a polycarbonate resin or a polyester resin.

  Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having a group derived from these materials. Be

Also, the charge transport material may contain a plurality of types together. Hereinafter, specific examples of the charge transport material are shown.

  The content of the charge transport material in the charge transport layer is preferably 20% by mass to 60% by mass, and more preferably 30% by mass to 50% by mass, with respect to the total mass of the charge transport layer. preferable.

（一般式（Ｉ）において、Ｘ^１は、単結合、酸素原子、２価のアルキリデン基又は２価のシクロアルキリデン基を表す。Ｒ^１１〜Ｒ^１８は、それぞれ独立に水素原子又はアルキル基を表す。）

（一般式（Ｉ−１）において、Ｒ^１１１は、水素原子、メチル基、エチル基、フェニル基を表す。Ｒ^１１２、Ｒ^１１３は、それぞれ独立に炭素数１〜４のアルキル基を表す。Ｒ^１１４〜Ｒ^１１７は、それぞれ独立に水素原子又はメチル基を表す。ｍは、括弧内の繰り返し数を示し、０〜３の整数である。） The polycarbonate resin is characterized by having a structure represented by the general formula (I), and further, the structure represented by the general formula (I) is characterized by having a structure represented by the general formula (I-1) Do.

(In the general formula (I), X ¹ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{11 to} R ¹⁸ each independently represent a hydrogen atom or an alkyl group .)

(In the general formula (I-1), R ¹¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ¹¹² and R ¹¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{114 to} R ¹¹⁷ each independently represent a hydrogen atom or a methyl group, m represents the number of repetitions in parentheses, and is an integer of 0 to 3)

中でも式（Ｉ−１−１）で示される構造が電荷移動度を高め、ゴースト現象を抑制する点で好ましい。 Specific examples of the structure represented by the general formula (I-1) are shown below.

Among them, the structure represented by the formula (I-1-1) is preferable in terms of enhancing charge mobility and suppressing the ghost phenomenon.

中でも、式（Ｉ−２）を有していることが好ましい。 It is more preferable that the structure represented by the general formula (I) has a structure other than (I-1). Examples of the structure that may be included include the following structures.

Among them, it is preferable to have the formula (I-2).

  Furthermore, Formula (I-2) and Formula (I-3-1), Formula (I-3-2), Formula (I-3-3), Formula (I-4) or Formula (I-5) It is preferable to have any of Among them, it is preferable to have the formula (I-2) and the formula (I-4).

中でも式（ＩＩ−１）で示される構造を有することが好ましい。 Examples of the structure represented by the general formula (II) of the polyester resin of the present invention include structures derived from carboxylic acids such as terephthalic acid, isophthalic acid, biphenyl dicarboxylic acid, aliphatic dicarboxylic acid, and naphthalene dicarboxylic acid. Specifically, the following structural examples and the like can be mentioned.

Among them, it is preferable to have a structure represented by formula (II-1).

中でも式（ＩＩＩ−１−１）で示される構造が電荷移動度を高め、ゴースト現象を抑制する点で好ましい。 Specific examples of the structure represented by the general formula (III-1) are shown below.

Among them, the structure represented by the formula (III-1-1) is preferable in terms of enhancing charge mobility and suppressing the ghost phenomenon.

中でも、（ＩＩＩ−２−１）、（ＩＩＩ−２−２）、（ＩＩＩ−２−３）で示される構造を有していることが好ましい。 The structure represented by the general formula (III) more preferably has a structure other than (III-1). Examples of the structure that may be included include the following structures.

Especially, it is preferable to have the structure shown by (III-2-1), (III-2-2), and (III-2-3).

  Furthermore, in the structure represented by (III), the content of the structure represented by formulas (III-2-1), (III-2-2) and (III-2-3) is 35 mol% or more and 70 mol% It is preferable that it is the following.

  In the present invention, the copolymerization form of the polycarbonate resin and the polyester resin may be any form such as block copolymerization, random copolymerization, alternating copolymerization, etc. However, in terms of obtaining high responsiveness of random copolymerization. Particularly preferred.

  The charge transport layer may use another resin as the binder resin in addition to the above polyester resin. Polycarbonate resins, siloxane resins, polymethacrylic acid ester resins, polysulfone resins, polystyrene resins and the like can be mentioned. Other resins may be blended or copolymerized with one another.

  The content ratio (mass ratio) of the charge transport substance to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 10:10. Although the charge mobility can be enhanced by increasing the amount of charge transport material, it is better to enhance the charge mobility as a resin and reduce the ratio of the charge transport material as much as possible for the improvement of the ghost phenomenon. It is presumed that the reason for this is that if the charge mobility is increased with the resin, the retained charge in the charge transport layer decreases.

  The charge transport layer can be formed by forming a coating of a charge transport layer coating solution prepared by dissolving a charge transport substance and a binder resin in a solvent, and drying the coating. Examples of the solvent used for the coating solution for forming the charge transport layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

The charge transport layer may also contain additives such as an antioxidant, an ultraviolet light absorber, a plasticizer, a leveling agent, a slipperiness imparting agent, and an abrasion resistance improver.
Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane modified resins, silicone oils, fluorocarbon resin particles, polystyrene resin particles, polyethylene resin particles, alumina particles, boron nitride particles and the like are listed. Be

  The average film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

  The charge transport layer can be formed by preparing a coating solution for charge transport layer containing the above-described respective materials and a solvent, forming this coating film, and drying it. Examples of the solvent used for the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Among these solvents, ether solvents or aromatic hydrocarbon solvents are preferable.

(2) Single-Layer Type Photosensitive Layer A single-layer type photosensitive layer is formed by preparing a coating solution for a photosensitive layer containing a charge generating substance, charge transporting substance, resin and solvent, forming this coating film, and drying it. can do. As the charge generating material, the charge transporting material, and the resin, the same materials as the examples of the materials in the above-mentioned “(1) laminated photosensitive layer” can be used.

<Protective layer>
A protective layer as a surface layer may be provided on the photosensitive layer as long as the effects of the present invention are exhibited. The protective layer preferably contains conductive particles or charge transport materials, and a binder resin. Furthermore, the protective layer may contain an additive such as a lubricant. In addition, the binder resin itself of the protective layer may have conductivity or charge transportability. In that case, the protective layer may not contain the conductive particles and the charge transport substance separately. The binder resin for the protective layer may be a thermoplastic resin or a curable resin obtained by curing with heat, light, radiation (electron beam or the like).

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. These do not limit the present invention.

<Production Example of Polycarbonate Resin>
<Polycarbonate resin (1)>
53.0 g (0.196 mol) of 2,2-bis (4-hydroxyphenyl) -4-methylpentane (product code D3267, manufactured by Tokyo Chemical Industry Co., Ltd.) in 1100 ml of a 5% by mass aqueous solution of sodium hydroxide, 0.1 g of fight was dissolved. To this was added 500 ml of methylene chloride, and while stirring and maintaining at 15 ° C., 60 g of phosgene was then blown in for 60 minutes.
After completion of the phosgene blowing, 1 g of p-t-butylphenol (manufactured by Tokyo Chemical Industry Co., Ltd., product code B0383) was added as a molecular weight modifier, and the mixture was stirred to emulsify the reaction liquid. After emulsification, 0.3 ml of triethylamine was added, and the mixture was stirred at 23 ° C. for 1 hour for polymerization.
After completion of the polymerization, the reaction solution was separated into an aqueous phase and an organic phase, the organic phase was neutralized with phosphoric acid, and water washing was repeated until the conductivity of the washing solution (water phase) became 10 μS / cm or less. The obtained polymer solution was added dropwise to warm water maintained at 45 ° C., and the solvent was removed by evaporation to obtain a white powdery precipitate. The obtained precipitate was filtered and dried at 110 ° C. for 24 hours to obtain a polycarbonate resin (1) having a structure represented by formula (I-1-1).

<Polycarbonate resin (2) to (4)>
Polycarbonate resins (2) to (4) having the molar ratio of the structure represented by the general formula (I) as shown in Table 1 by changing the molar amount of the raw materials used in the production example of the polycarbonate resin (1) I got

をジクロロメタンに溶解させ、酸ハロゲン化物溶液を調製した。また、別途、下記式で示されるジオール２４．２ｇ、

下記式で示されるジオール２７ｇ

を１０％水酸化ナトリウム水溶液に溶解させ、重合触媒としてトリブチルベンジルアンモニウムクロライドを添加して攪拌し、ジオール化合物溶液を調製した。
次に、上記酸ハロゲン化物溶液を上記ジオール化合物溶液に攪拌しながら加え、重合を開始した。重合は、反応温度を２５℃以下に保ち、攪拌しながら、３時間行った。
重合反応中に重合調整剤として、ｐ−ターシャルブチルフェノールを加えた。その後、酢酸の添加により重合反応を終了させ、水相が中性になるまで水での洗浄を繰り返した。
洗浄後、ジクロロメタン溶液を攪拌下のメタノールに滴下して、重合物を沈殿させ、この重合物を真空乾燥させてポリエステル樹脂Ａ７２．３ｇを得た。 <Production Example of Polyester Resin>
<Polyester resin (1)>
59 g of dicarboxylic acid halide represented by the following formula

Was dissolved in dichloromethane to prepare an acid halide solution. Also, separately, 24.2 g of diol represented by the following formula,

27 g of diol represented by the following formula

Was dissolved in a 10% aqueous solution of sodium hydroxide, tributylbenzylammonium chloride was added as a polymerization catalyst, and the mixture was stirred to prepare a diol compound solution.
Next, the acid halide solution was added to the diol compound solution while stirring to initiate polymerization. The polymerization was carried out for 3 hours with stirring while maintaining the reaction temperature at 25 ° C. or less.
During the polymerization reaction, p-tert-butylphenol was added as a polymerization modifier. Thereafter, the polymerization reaction was terminated by the addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.
After washing, the dichloromethane solution was dropped into methanol under stirring to precipitate a polymer, and this polymer was vacuum dried to obtain 72.3 g of polyester resin A.

  The obtained polyester resin A has 100% by mole of the structure represented by the formula (II-1) among the structures represented by the formula (II), and the structure represented by the formula (III) is represented by the formula It was a polyester resin having 50 mol% of a structure represented by (III-1-1) and 50 mol% of a structure represented by formula (III-2-3). In addition, the weight average molecular weight of the obtained polyester resin A was 85,000.

<Polyester resin (2) to (5)>
Polyester resins (2) to (5) having a molar ratio of the structure represented by the general formula (III) as shown in Table 2 by changing the molar amount of the raw materials used in the production example of polyester resin (1) I got

<Production Example of Electrophotographic Photoreceptor>
<Electrophotographic photosensitive member (1)>
An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as a support (conductive support).

[Conductive layer]
Next, 100 parts of zinc oxide particles (specific surface area: 15 m ² / g, average particle size: 70 nm, powder resistance: 3.7 × 10 ⁵ Ω · cm) were stirred and mixed with 500 parts of toluene.
To this, 1.5 parts of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (trade name: KBM 603, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent is added and stirred for 6 hours did.
Then, toluene was distilled off under reduced pressure and the residue was heated at 140 ° C. for 6 hours for drying to obtain zinc oxide particles surface-treated with a silane coupling agent.
Next, 15 parts of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol resin and blocked isocyanate (trade name: Desmodur BL 3175/1, manufactured by Sumika Bayer Urethane Co., Ltd.) 15 parts were dissolved in a mixed solvent of 73.5 parts of methyl ethyl ketone / 73.5 parts of 1-butanol.
In this solution, 81 parts of zinc oxide particles surface-treated with the above-mentioned silane coupling agent, 0.8 parts of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.), and zinc octylate (trade name) : 0.81 parts of zinc oxide zinc 8%, manufactured by Nippon Chemical Industrial Co., Ltd., added to a sand mill using glass beads with a diameter of 0.8 mm, and dispersed for 3 hours in an atmosphere of 23 ± 3 ° C. did.
After dispersion treatment, 0.01 part of silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) and 5 parts of silicone resin particles (trade name: Tospearl 145, manufactured by GE Toshiba Silicone Co., Ltd.) were added thereto. .6 parts were added and stirred to prepare a coating solution for conductive layer.
The coating solution for a conductive layer was dip-coated on the support, and the obtained coating film was dried at 150 ° C. for 30 minutes and thermally cured to form a conductive layer having a thickness of 30 μm.

ブロックされたイソシアネート化合物（商品名：ＳＢＮ−７０Ｄ、旭化成ケミカルズ製）１５部、樹脂として、ポリビニルアルコール樹脂（商品名：ＫＳ−５Ｚ、積水化学工業製）０．９７部、触媒としてヘキサン酸亜鉛（ＩＩ）（商品名：ヘキサン酸亜鉛（ＩＩ）、三津和化学薬品製）０．１５部とを、１−メトキシ−２−プロパノール８８部とテトラヒドロフラン８８部の混合溶媒に溶解した。
この溶液にイソプロピルアルコールに分散された平均一次粒子径が９〜１５ｎｍのシリカスラリー（製品名：ＩＰＡ−ＳＴ−ＵＰ、日産化学工業（株）製、固形分濃度：１５質量％、粘度：９ｍＰａ・ｓ）を、東京スクリーン（株）製のナイロンスクリーンメッシュシート（製品名：Ｎ−Ｎｏ．１５０Ｔ）を通し１．８部加え、１時間撹拌した。その後、ＡＤＶＡＮＴＥＣ（株）製のテフロン（登録商標）製フィルター（製品名：ＰＦ０２０）を用いて加圧ろ過し、下引き層用塗布液を調製した。
この下引き層用塗布液を導電層上に浸漬塗布し、得られた塗膜を２０分間１７０℃で加熱し、硬化（重合）させることによって、導電層上に膜厚が０．７μｍの下引き層を形成した。 [Sublayer]
Next, 8.5 parts of a compound represented by the following formula as a charge transporting substance,

15 parts of blocked isocyanate compound (trade name: SBN-70D, manufactured by Asahi Kasei Chemicals), 0.97 parts of polyvinyl alcohol resin (trade name: KS-5Z, manufactured by Sekisui Chemical Co., Ltd.) as a resin, zinc hexanoate as a catalyst II) (trade name: zinc (II) hexanoate, manufactured by Mitsuwa Chemical Co., Ltd.) and 0.15 part were dissolved in a mixed solvent of 88 parts of 1-methoxy-2-propanol and 88 parts of tetrahydrofuran.
Silica slurry having an average primary particle diameter of 9 to 15 nm dispersed in isopropyl alcohol in this solution (Product name: IPA-ST-UP, manufactured by Nissan Chemical Industries, Ltd., solid content concentration: 15% by mass, viscosity: 9 mPa · 1.8 parts of nylon screen mesh sheets (product name: N-No. 150T) manufactured by Tokyo Screen Co., Ltd. were added, and the mixture was stirred for 1 hour. Thereafter, pressure filtration was carried out using a Teflon (registered trademark) filter (product name: PF020) manufactured by ADVANTEC Co., Ltd. to prepare a coating solution for undercoat layer.
The undercoat layer coating solution is dip-coated on the conductive layer, and the obtained coating film is heated at 170 ° C. for 20 minutes to cure (polymerize), whereby the film thickness is 0.7 μm or less on the conductive layer. A pull layer was formed.

[Charge generation layer]
Next, 2 parts of polyvinyl butyral (trade name: SLEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 100 parts of cyclohexanone.
To this solution was added 4 parts of hydroxygallium phthalocyanine crystal (charge generating substance) having a strong peak at 7.4 ° and 28.1 ° of Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction. .
This was placed in a sand mill using glass beads with a diameter of 1 mm, and dispersed for 1 hour in an atmosphere of 23 ± 3 ° C. After the dispersion treatment, 100 parts of ethyl acetate was added thereto to prepare a coating solution for charge generation layer.
The coating solution for charge generation layer was dip-coated on the undercoat layer, and the obtained coating film was dried at 90 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.20 μm.

[Charge transport layer]
Next, 5 parts of a compound represented by the formula (CTM-1), 2 parts of a compound represented by the formula (CTM-3), and 10 parts of a polycarbonate resin (1) synthesized in the polycarbonate resin synthesis example, 33 parts of dimethoxymethane The mixture was dissolved in a mixed solution of 15 parts of ortho-xylene and 25 parts of methyl benzoate to prepare a charge transport layer coating solution.
The charge transport layer coating solution is dip-coated on the charge generation layer to form a coating film, and the obtained coating film is dried at 130 ° C. for 30 minutes to form a charge transport layer having a thickness of 22 μm (surface Layer).
Thus, an electrophotographic photosensitive member (1) having a support, a conductive layer, an undercoat layer, a charge generation layer and a charge transport layer in this order was produced.

<Electrophotographic photosensitive member (2) to (9)>
Electrophotographic photosensitive members (2) to (9) were produced in the same manner as in the production example of electrophotographic photosensitive member (1) except that the charge transport substance and the polycarbonate resin or polyester resin were changed as shown in Table 3.

<Example of producing thermally expanded microcapsule particles>
Production Examples 1 to 4 are methods for producing thermally expanded microcapsule particles 1 to 4 which are materials for forming insulating hollow particles. Moreover, unless otherwise specified, commercially available high purity products were used as reagents and the like which are not specified. In each example, a charging roller was produced as a charging member.

Thermal Expansion Capsule Particle Production Example 1
An aqueous mixture consisting of the following ingredients was prepared:
4000 parts by mass of ion exchange water.
Dispersion stabilizer: 8 parts by weight of colloidal silica and 0.15 parts by weight of polyvinyl pyrrolidone.
Next, an oily mixture comprising the following components was prepared.
Polymerizable monomer: 50 parts by mass of acrylonitrile, 45 parts by mass of methacrylonitrile and 5 parts by mass of methyl methacrylate.
Inclusion substance: 4.2 parts by mass of isopentene and 7.5 parts by mass of normal hexane.
Polymerization initiator: 0.75 parts by mass of dicumyl peroxide.
This oily mixture was added to the aqueous mixture, and 0.4 parts by mass of sodium hydroxide was further added to prepare a dispersion.
The resulting dispersion is stirred and mixed for 3 minutes using a homogenizer, charged into a nitrogen-replaced polymerization reaction vessel, and reacted at a pressure of 0.5 MPa and 60 ° C. for 20 hours under stirring by a homogenizer at 300 rpm. The product was prepared. The obtained reaction product was repeatedly filtered and washed with water, and then dried at 80 ° C. for 5 hours to produce thermally expanded microcapsule particles.
The obtained thermally expanded microcapsule particles were sieved by a dry air flow classifier (trade name: CRUSHEL N-20: manufactured by Seishin Enterprise Co., Ltd.) to obtain thermally expanded microcapsule particles 1. As classification conditions, the number of revolutions of the classification rotor was set to 1600 rpm.

As the average particle size of the thermally expanded microcapsule particles, “volume average particle size” determined by the following method was adopted. The measurement is performed using a laser diffraction type particle size distribution analyzer (trade name: Coulter LS-230 particle size distribution analyzer, manufactured by Coulter, Inc.). For measurement, an aqueous module is used, and pure water is used as a measurement solvent. The inside of the measurement system of the particle size distribution analyzer is washed with pure water for about 5 minutes, and 10 mg to 25 mg of sodium sulfite is added to the measurement system as an antifoaming agent to execute the "background function". Next, 3 to 4 drops of anionic surfactant are added to 50 ml of pure water, and 1 mg to 25 mg of a measurement sample is further added. The aqueous solution in which the sample is suspended is dispersed by an ultrasonic disperser for 1 to 3 minutes to prepare a test sample solution. The test sample solution is gradually added into the measurement system of the measurement device, and the concentration of the test sample in the measurement system is adjusted to perform measurement so that “PIDS” on the screen of the device is 45% or more and 55% or less. . The volume average particle diameter is calculated from the obtained volume distribution.
Furthermore, the volume resistance of the obtained hollow particles was measured as described above.
The volume-average particle size of the obtained thermally expanded microcapsule particles 1 was 7.0 μm, and the volume resistivity was 3.8 × 10 ¹⁰ Ωcm.

Thermal Expansion Microcapsule Particle Production Example 2
Thermal expansion microcapsule particles 2 were obtained in the same manner as in Production Example 1 except that 14 parts by mass of colloidal silica was used, and the rotation number of the homogenizer during polymerization was 1200 rpm, and the rotation number of the classification rotor was 1800 rpm. The volume-average particle size of the obtained thermally expanded microcapsule particles was 3.5 μm, and the volume resistivity was 3.7 × 10 ¹⁰ Ωcm.

Thermal Expansion Microcapsule Particle Production Example 3
Thermal expansion microcapsule particles 3 were obtained in the same manner as in Production Example 1 except that 4 parts by mass of colloidal silica was used, and the rotation speed of the homogenizer during polymerization was 100 rpm, and the rotation speed of the classification rotor was 1350 rpm. The volume-average particle size of the obtained thermally expanded microcapsule particles was 25.5 μm, and the volume resistivity was 4.1 × 10 ¹⁰ Ωcm.

Thermal Expansion Microcapsule Particle Production Example 4
Thermally expanded microcapsule particles 4 were obtained in the same manner as in Production Example 1, except that 1 part by mass of colloidal silica was used, and the number of revolutions of the homogenizer during polymerization was 200 rpm, and the number of revolutions of the classification rotor was 1500 rpm. The volume-average particle size of the obtained thermally expanded microcapsule particles was 50.0 μm, and the volume resistivity was 4.0 × 10 ¹⁰ Ωcm.

Example 1
(Preparation of Unvulcanized Rubber Composition for Elastic Layer)
The material shown in Table 4 below is mixed with a 6 liter pressure kneader (product name: TD 6-15 MDX, manufactured by Toshin Co., Ltd.) for 16 minutes at a filling rate of 70 vol% and a blade rotational speed of 30 rpm for A rubber composition I got

Next, the materials shown in Table 5 below were treated with an open roll with a roll diameter of 12 inches (0.30 m), with a front roll rotation speed of 10 rpm, a rear roll rotation speed of 8 rpm, and a roll gap of 2 mm, totaling 20 times of left and right turnaround Carried out. Thereafter, the roll gap was set to 0.5 mm, and thin threading was performed 10 times to obtain an unvulcanized rubber composition for the surface layer.

(Forming a vulcanized rubber layer)
The core metal was coated with the unvulcanized rubber composition for the surface layer with a crosshead extruder having a cylinder diameter of 70 mm and L / D = 20 to obtain a crown-shaped unvulcanized rubber roller. At this time, the extrusion temperature was 100 ° C., and the screw rotation speed was 9 rpm, and molding was performed while changing the core metal feed rate. Core metal length 252.5 mm, core metal diameter 6 mm, inner diameter of die of crosshead extrusion molding machine 8.5 mm, axial outer central diameter of unvulcanized rubber roller 8.25 mm, outer diameter of end 8. It was 05 mm.
Thereafter, the unvulcanized rubber layer is vulcanized in an electric hot air oven at a temperature of 160 ° C. for 30 minutes and then heated at 160 ° C. for 30 minutes, and both ends of the vulcanized rubber layer are cut. By setting the length in the direction to 232 mm, a vulcanized rubber roller was obtained.

(UV irradiation treatment)
The manufactured vulcanized rubber roller was irradiated with ultraviolet light to perform curing treatment, to obtain a charging member of this example. At this time, ultraviolet light with a wavelength of 254 nm was irradiated such that the integrated light amount became 9000 mJ / cm ² . A low-pressure mercury lamp (Harrison Toshiba Lighting Co., Ltd.) was used for ultraviolet irradiation.

(Observation of particles)
The hollow particles on the surface of the charging member (the surface of the surface layer) were observed with a confocal microscope (trade name: OPTELICS HYBRID, manufactured by Lasertec Corporation). The observation conditions were an objective lens 50 times, a pixel count of 1024 pixels, and a height resolution of 0.1 μm. The particles were present in the exposed state.

(Measurement of average hollow diameter and average thickness of insulating hollow particles)
A focused ion beam-scanning electron microscope (trade name: Zeiss NVision 40 FIB, manufactured by Carl Zeiss) was used to measure the average hollow diameter of the insulating hollow particles and the average thickness of the shells of the insulating hollow particles. An image was acquired while thinly scraping the charging member with a focused ion beam to obtain a 3D image of the insulating hollow particles.
Specifically, first, a cross-sectional image of an arbitrary convex portion was taken with a focused ion beam at a thickness of 0.1 μm, including the periphery thereof. A 3D image showing the shape of the insulating hollow particle was obtained by reconstructing an image acquired based on this cross-sectional image into a 3D image.
From the volume of the hollow portion of the 3D image, the diameter (volume sphere equivalent diameter) of the hollow portion when the hollow portion was approximated to a spherical shape was calculated. A value obtained by averaging this value at 100 points (100 hollow portions) was taken as an average hollow portion diameter.
In addition, the thickness of the shell of the insulating hollow particle of the 3D image is measured at any place for one hollow particle, and the average value of 100 points (100 hollow portions) is the average of the shell of the insulating hollow particle. It was a thickness.
The average hollow diameter was 28 μm, and the average thickness of the shell was 1.30 μm.

(10-point average roughness)
The ten-point average roughness Rzjis is measured according to JIS B 0601-2001 using a surface roughness measuring device (trade name: Surfcoder SE-3500, manufactured by Kosaka Laboratory Ltd.). The measurement was made at three points in the axial direction of the target member and at six points in total in two points in the circumferential direction at each point, and the average value was taken as the ten-point average roughness Rzjis.

The measurement conditions are as follows.
(Measurement environment) Room temperature: 23 ° C ± 2 ° C, humidity: 53% ± 10%
(Standing environment) 23 ° C ± 2 ° C, 53% ± 10%, 5 hours or more under environment (contact needle) Tip shape: Conical with spherical tip, taper angle of cone: 60 °
Tip radius: 2 μm, material: diamond (measurement force) 0.75 mN
(Rate of change in measuring force) 0 N / m
(Measurement speed) 0.5 mm / s
(Cutoff) λc: 0.8 mm, λs: 2.5 μm
(Cutoff type) 2 CR (phase non-guaranteed)
(Reference length) 0.8 mm
(Evaluation length) 8.0 mm
(Others) Approach: 1.25 mm, second run: 1.25 mm
(Pitch) 1 μm
(Filter) Gaussian

(Evaluation of undercharged image)
The prepared charging member and electrophotographic photosensitive member (2) are incorporated into an electrophotographic process cartridge for an electrophotographic apparatus (trade name "LBP 712 Ci", Canon Inc.) for A4 paper longitudinal output, and this process cartridge is used for the above electronic The built-in image evaluation was performed on a photographic device. Image output was performed under a 15 ° C./10% RH environment. The evaluation image is a halftone image (image of intermediate density) on A4 paper. The output image was evaluated by visually observing the uniformity of the halftone image output after printing (after endurance) at 30,000 prints with 1% printing density. From the obtained image after durability, the image quality in the form of horizontal stripes generated by the contamination of the surface of the charging member with toner or the like was evaluated according to the following criteria. The unevenness in the image on the horizontal line is caused by the discharge in the gap in the vicinity of the nip with the electrophotographic photosensitive member in the rotational direction in the charging roller of the DC charging type. It is known that this phenomenon is a phenomenon in which a large number of horizontal stripes are generated because discharge occurs intermittently after passing through the nip (downstream side in the direction of rotation) without rising as much. did.
Rank A: There is no image unevenness in the form of horizontal stripes.
Rank B: Horizontal stripe-like image unevenness occurred very slightly.
Rank C: Horizontal stripe-like image unevenness occurred.

<Evaluation of ghost phenomenon suppression effect>
As described above, the laser printer is set not to emit light, the manufactured electrophotographic photosensitive member is attached to the process cartridge for black color, the process cartridge is attached to the station of the black process cartridge, and the image is displayed. I output it.
The evaluation was performed under the environment of temperature 23 ° C. and humidity 50% RH. First, 5,000 full color images (character images with 1% printing rate for each color) are output using A4 size plain paper, and then 1 solid white image, 5 images for ghost phenomenon evaluation, solid black image The image output was continuously performed in order of one image and five images for evaluating the ghost phenomenon.
As shown in FIG. 4, after the ghost image for evaluation of the ghost phenomenon has a square “black image 42” in the “white image 41” at the beginning of the image, “one-dot Keima pattern halftone shown in FIG. "Image 43" is created. In FIG. 4, the "ghost 44" portion is a portion after one rotation on the electrophotographic photosensitive member which outputs the "black image", and is a portion where the ghost phenomenon due to the "black image" may appear. .
The ghost phenomenon was evaluated by measuring the difference between the image density of the halftone image of the 1-dot Keima pattern and the image density of the ghost portion. With a spectrodensitometer (trade name: X-Rite 504/508, manufactured by X-Rite), 10 points of difference in density were measured in one ghost evaluation image. This operation was performed on all ten ghost phenomenon evaluation images, and an average of a total of 100 points was calculated, and evaluation was made according to the following criteria.
Rank A: concentration difference is 0.04 or less Rank B: concentration difference is 0.06 or less Rank C: concentration difference is 0.08 or less

[Examples 2 to 8]
As shown in Table 6, electrophotographic process cartridges of Examples 2 to 8 were produced in the same manner as in Example 1 except that the material to be hollow particles of the charging member and the temperature of the vulcanization / foaming step were changed. Table 6 shows the details and evaluation results of the charging member and the electrophotographic photosensitive member produced.

Comparative Examples 1 to 4
As in Table 6, electrophotographic process cartridges of Comparative Examples 1 to 4 were produced in the same manner as in Example 1 except that the material to be hollow particles of the charging member and the temperature of the vulcanization / foaming step were changed. Table 6 shows the details and evaluation results of the charging member and the electrophotographic photosensitive member produced.

Comparative Example 5
Preparation Example Preparation of Surface Layer Coating The following were mixed to prepare a mixture.
Polyamide resin (trade name "Alamine CM 8000": manufactured by Toray Industries, Inc.) 100 parts by mass as a binder for the surface layer 20 parts by mass of carbon black as conductive particles (equivalent to 10% by volume)
Cross-linked acrylic monodispersed particles (trade name "Matsumoto Microsphere FN-80SDE": manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) 4 parts by mass Ethanol 400 parts by mass The mixed solution and glass beads having an average particle diameter of 0.8 mm are put together in a glass bottle The paint for surface layer was prepared by dispersing for 60 hours using a paint shaker disperser.
A vulcanized rubber roller was obtained by the same method except that the thermally expanded microcapsule particles 1 were removed from the unvulcanized rubber composition of Example 1.
The surface layer paint was dip-coated on the surface of the vulcanized rubber roller to obtain a charging member. Comparative Example 5 was evaluated in the same manner as in Example 1 except that the charging member was incorporated. Table 6 shows the details and evaluation results of the charging member and the electrophotographic photosensitive member produced.

[Examples 9 to 15]
Electrophotographic cartridges of Examples 9 to 15 were produced in the same manner as in Example 1 except that the electrophotographic photosensitive members were changed as shown in Table 7. Details and evaluation results of the charging member and the electrophotographic photosensitive member produced in Table 7 are shown.
The crosslinking initiation temperature (Tc) was 155 ° C. in all examples and comparative examples.
The foaming start temperature (Ts) was 138 ° C. in all examples and comparative examples.
The primary vulcanizing temperature dependency of the average hollow inner diameter and the average thickness of the shell in Examples 1, 3, 5 and 6 using thermally expanded microcapsule particles 1 will be described. As the primary vulcanization temperature is higher, foaming is given priority over vulcanization, so the average hollow inner diameter is larger and the average thickness of the shell is thinner.

In Examples 1 to 15 and Comparative Examples 1 to 4, hollow particles were all exposed. In Comparative Example 5, hollow particles were contained in the surface layer containing a polyamide resin as a binder.
Since all of Examples 1 to 15 and Comparative Examples 1 to 5 use the electrophotographic photosensitive member having the structure of the present invention, the amount of charge retention is small, and all the ghosts are rank A.

As apparent from Tables 6 and 7, in Comparative Examples 1 to 4, the average hollow portion diameter of the hollow particles was out of the range of the present invention, and the evaluation of the charge insufficient image was rank C. It is considered that the discharge in the hollow of the insulating hollow particles is reduced. In Comparative Example 5, the evaluation of the charge insufficient image was Rank C. Since the surface layer is formed by coating and the hollow particles are not exposed and covered with the surface layer containing conductive particles, the apex of the convex portion has the same potential as the surrounding binder, and the discharge charge It is thought that the amount was not enough.
On the other hand, in Examples 1 to 15, in all the evaluations of the charge-deficient images, good images having no problem in practical use are obtained at ranks A to C or higher.
In Examples 1 to 15 and Comparative Examples 1 to 5, all of the ghost evaluations were rank A because the electrophotographic photosensitive members having the structure of the present invention were used.

11 Electrophotographic photosensitive member surface 12 Hollow particle 13 Binder 14 Discharge inside hollow 15 Charge of shell of hollow particle 16 Discharge

Claims (4)

An electrophotographic process cartridge detachably configured to a main body of an electrophotographic apparatus, comprising: a charging member; and an electrophotographic photosensitive member contact-charged by the charging member,
The charging member is
A conductive support and a conductive surface layer,
The surface of the surface layer includes an insulating hollow particle and a binder, and the hollow particle is held by the binder, and the hollow particle forms an exposed protrusion on the surface of the surface layer.
The average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, and
The average hollow part diameter of the hollow particles is 7 μm or more and 100 μm or less,
The electrophotographic photosensitive member is
Having a surface layer containing a charge transport material and a polycarbonate resin or a polyester resin,
The polycarbonate resin has a structure represented by the general formula (I),
The polyester resin is
An electrophotographic process cartridge having a structure represented by the general formula (II) and a structure represented by the general formula (III):

(In the general formula (I), X ¹ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{11 to} R ¹⁸ each independently represent a hydrogen atom or an alkyl group .)

(In the general formula (II), X ² represents a divalent group.)

(In the general formula (III), X ³ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{31 to} R ³⁸ each independently represent a hydrogen atom or an alkyl group. ). The polycarbonate resin having a structure represented by the general formula (I) has a structure represented by a general formula (I-1),

(In the general formula (I-1), R ¹¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ¹¹² and R ¹¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{114 to} R ¹¹⁷ each independently represent a hydrogen atom or a methyl group, m represents the number of repetitions in parentheses, and is an integer of 0 to 3)
Furthermore, the polyester resin having the structure represented by the general formula (III) has a structure represented by the general formula (III-1),

(In the general formula (III-1), R ³¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ³¹² and R ³¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{314 to} R ³¹⁷ each independently represent a hydrogen atom or a methyl group, n represents the number of repetitions in parentheses, and is an integer of 0 to 3).
An electrophotographic process cartridge according to claim 1. An electrophotographic apparatus comprising a charging member and an electrophotographic photosensitive member contact-charged by the charging member, comprising:
The charging member is
A conductive support and a conductive surface layer,
The surface of the surface layer includes an insulating hollow particle and a binder, and the hollow particle is held by the binder, and the hollow particle forms an exposed protrusion on the surface of the surface layer.
The average thickness of the shell of the hollow particles is 0.05 μm or more and 3.00 μm or less, and
The average hollow part diameter of the hollow particles is 7 μm or more and 100 μm or less,
The electrophotographic photosensitive member is
Having a surface layer containing a charge transport material and a polycarbonate resin or a polyester resin,
The polycarbonate resin has a structure represented by the general formula (I),
The polyester resin is
An electrophotographic apparatus characterized by having a structure represented by the general formula (II) and a structure represented by the general formula (III):

(In the general formula (I), X ¹ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{11 to} R ¹⁸ each independently represent a hydrogen atom or an alkyl group .)

(In the general formula (II), X ² represents a divalent group.)

(In the general formula (III), X ³ represents a single bond, an oxygen atom, a divalent alkylidene group or a divalent cycloalkylidene group. R ^{31 to} R ³⁸ each independently represent a hydrogen atom or an alkyl group. ). The polycarbonate resin having a structure represented by the general formula (I) has a structure represented by a general formula (I-1),

(In the general formula (I-1), R ¹¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ¹¹² and R ¹¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{114 to} R ¹¹⁷ each independently represent a hydrogen atom or a methyl group, m represents the number of repetitions in parentheses, and is an integer of 0 to 3)
Furthermore, the polyester resin having the structure represented by the general formula (III) has a structure represented by the general formula (III-1),

(In the general formula (III-1), R ³¹¹ represents a hydrogen atom, a methyl group, an ethyl group or a phenyl group. R ³¹² and R ³¹³ each independently represent an alkyl group having 1 to 4 carbon atoms. ^{314 to} R ³¹⁷ each independently represent a hydrogen atom or a methyl group, n represents the number of repetitions in parentheses, and is an integer of 0 to 3).
An electrophotographic apparatus according to claim 3.

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