JP2022168830A - Member for electrophotography, method for manufacturing the same, process cartridge, and electrophotographic image forming apparatus - Google Patents

Abstract

To provide a member for electrophotography that can quickly recover from deformation even with low-hardness urethane elastomer and prevent a streak-like image defect.SOLUTION: A member for electrophotography comprises a shaft core body and an elastic layer provided on an outer periphery of the shaft core body. The elastic layer includes urethane elastomer having a matrix and a plurality of domains dispersed in the matrix. The modulus of elasticity of the domains measured on a cross section in a thickness direction of the elastic layer is lower than the modulus of elasticity of the matrix. The micro rubber hardness of the elastic layer at a temperature of 23°C is 20 or more and 50 or less. In an indentation test for the elastic layer at 23°C using a nanoindenter, when a Vickers indenter is pressed at a loading speed of 10 mN/30 sec, maintained at the load of 10 mN for 60 seconds, and then unloaded, the elastic layer has a strain of 1 μm or less after five seconds from the unloading.SELECTED DRAWING: Figure 2

Description

The present disclosure is directed to electrophotographic members used in electrophotographic image forming apparatuses such as electrophotographic copiers and printers (hereinafter also simply referred to as "image forming apparatuses"), and methods of manufacturing the same. The present disclosure is also directed to process cartridges and electrophotographic image forming apparatuses.

Electrophotographic image forming devices (copiers, facsimiles, printers, etc. using the electrophotographic method) mainly consist of an electrophotographic photoreceptor (hereinafter also referred to as a “photoreceptor”), a charging device, an exposure device, and a developing device. It consists of a device, a transfer device and a fixing device.
In an image forming apparatus, a photoreceptor is first charged by a charging member (hereinafter also referred to as a "charging roller") and then exposed to light to form an electrostatic latent image on the photoreceptor. Further, the toner in the toner container is applied onto a toner carrier (hereinafter also referred to as a "developing roller") by a toner regulating member, and is conveyed to a developing area by the developing roller. Then, the electrostatic latent image on the photoreceptor is developed at the contact portion between the photoreceptor and the developing roller by the toner conveyed to the development area. After that, the toner on the photoreceptor is transferred to the recording paper by the transfer means and fixed by heat and pressure. Toner remaining on the photoreceptor is removed by a cleaning member.

Conventionally, silicone rubber, acrylonitrile-butadiene rubber, epichlorohydrin rubber, and urethane elastomer have been used as materials for the elastic layer of such charging rollers and developing rollers. Among these materials, the urethane elastomer is preferably used as a material for the elastic layer because it has good abrasion resistance.
However, urethane elastomers are generally susceptible to compression set. Therefore, in the developing roller having an elastic layer containing a urethane elastomer, when a specific portion of the developing roller comes into contact with the toner regulating member for a long period of time and the specific portion is deformed, the deformation can be easily recovered. do not do. When a developing roller deformed in a specific portion is subjected to image formation, the obtained electrophotographic image may have a streak-like defect at a position corresponding to the deformed portion. Similarly, a charging roller having an elastic layer containing a urethane elastomer may also cause defective charging due to deformation of a specific portion of the charging roller, resulting in defects in an electrophotographic image. The compression set tends to increase as the hardness of the urethane elastomer decreases, and the above defects are more likely to occur.

In Patent Document 1, a polyisocyanate composed of a trimer of hexamethylene diisocyanate, a burette or a mixture thereof and a polyol containing a high-molecular-weight polypropylene polyol as a main component are reacted at an isocyanate index of 80 to 120. A conductive roller having a conductive elastic layer made of urethane elastomer is disclosed. Patent Document 1 discloses that the above conductive elastic layer reduces the permanent deformation of the roller and provides a conductive roller that is excellent in resilience against deformation caused by pressure contact with a photoreceptor or pressure contact with a roller or a blade. disclosed.

JP-A-9-34216

IEEE Transactions on SYSTEMS, MAN, AND CYBERNETICS, Vol. SMC-9, No. 1, January 1979, pp. 62-66

The present inventors studied the conductive roller according to Patent Document 1. As a result, it was found that the urethane elastomer according to Patent Document 1 still has room for improvement as a constituent material of the elastic layer of the developing roller and the charging roller used in a high-speed image forming apparatus. One aspect of the present disclosure is directed to providing an electrophotographic member having low hardness and quick recovery from deformation. Another aspect of the present disclosure is directed to a method of manufacturing an electrophotographic member having low hardness and excellent deformation recovery force. Another aspect of the present disclosure is directed to providing a process cartridge that contributes to the formation of high-quality electrophotographic images. Furthermore, another aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus capable of forming a high-quality electrophotographic image.

According to one aspect of the present disclosure, in an electrophotographic member comprising a mandrel and an elastic layer provided on the outer circumference thereof, the elastic layer comprises a matrix and a plurality of domains dispersed in the matrix. A parameter indicating the viscoelastic term of the domain measured in a viscoelastic image of the cross section in the thickness direction of the elastic layer with a scanning probe microscope, and a parameter indicating the viscoelastic term of the matrix The relationship with B is A < B, the micro rubber hardness of the elastic layer at a temperature of 23 ° C. is 20 or more and 50 or less, and the indentation test using a nanoindenter at 23 ° C. of the elastic layer A Vickers indenter is pressed at a load rate of 10 mN/30 seconds, a load of 10 mN is maintained for 60 seconds, and then unloaded for 5 seconds.

According to another aspect of the present disclosure, there is provided a process cartridge detachably attached to an image forming apparatus, the process cartridge including the electrophotographic member described above.

According to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including the above electrophotographic member.

Furthermore, according to another aspect of the present disclosure, there is provided a method for manufacturing the above electrophotographic member, comprising:
(i) reacting a first polyether having at least two isocyanate groups with a first polycarbonate polyol having at least two hydroxyl groups to obtain a urethane reactive emulsifier having at least two hydroxyl groups;
(ii) obtaining a dispersion of droplets comprising at least a portion of said urethane reactive emulsifier dispersed in a second polycarbonate polyol;
(iii) obtaining an elastic layer-forming mixture containing the dispersion and a polyisocyanate having at least two isocyanate groups; A method for producing an electrophotographic member is provided, comprising the step of reacting the urethane reactive emulsifier, the second polycarbonate polyol, and the polyisocyanate to obtain the elastic layer.

According to one aspect of the present disclosure, it is possible to obtain an electrophotographic member having low hardness and quick recovery from deformation. According to one aspect of the present disclosure, it is possible to obtain a method for manufacturing an electrophotographic member having low hardness and quick recovery from deformation. Further, according to one aspect of the present disclosure, it is possible to obtain a process cartridge that contributes to the formation of high-quality electrophotographic images. Furthermore, according to one aspect of the present disclosure, it is possible to obtain an electrophotographic image forming apparatus capable of forming a high-quality electrophotographic image.

1 is a schematic cross-sectional view showing an example of an electrophotographic member according to an aspect of the present disclosure; FIG. 1 is a schematic cross-sectional view of one form of an elastic layer of an electrophotographic member according to one aspect of the present disclosure; FIG. FIG. 4 is a diagram illustrating deformation of an elastic layer according to the present disclosure; It is a figure explaining the cutting-out position and direction of a cross section. 1 is a schematic diagram showing a method for manufacturing an electrophotographic member according to one embodiment of the present disclosure; FIG. 1 is a schematic cross-sectional view of an example of an image forming apparatus according to one aspect of the present disclosure; FIG. 1 is a schematic cross-sectional view of an example of a process cartridge according to one embodiment of the present disclosure; FIG.

In the present disclosure, the descriptions “XX or more and YY or less” and “XX to YY” representing numerical ranges mean numerical ranges including the lower and upper limits, which are endpoints, unless otherwise specified. In addition, when numerical ranges are stated stepwise, any combination of the upper and lower limits of each numerical range is disclosed.
In recent years, amid growing demand for higher print speeds and higher quality electrophotographic images, the elastic layers of developing rollers and charging rollers need to be able to recover more quickly from deformation. is becoming necessary. However, according to the studies of the present inventors, the urethane elastomer according to Patent Literature 1 still has an insufficient recovery speed from deformation. Patent Document 1 describes that the compression set of the urethane elastomer according to Patent Document 1 was measured according to Japanese Industrial Standards (JIS) K6301, and the compression conditions were 70° C. and 22 hours. That is, in Patent Document 1, the compression set of the urethane elastomer according to Patent Document 1 is measured by compressing at a temperature of 70° C. for 22 hours, releasing from the compressed state, and measuring the thickness after standing for 30 minutes. It is thought that it is done by However, the results of such tests show that even urethane elastomers exhibiting low compression set still require deformation in order to obtain elastic layers for developing rollers and charging rollers for high-speed image forming apparatuses. Slow recovery from Therefore, the present inventors have recognized that it is necessary to develop an elastic layer that exhibits faster deformation recovery while maintaining flexibility.

Here, in general, when the micro-rubber hardness of the elastic layer is lowered, the compression set increases and the recovery speed from deformation also decreases. On the other hand, increasing the elastic modulus of the elastic layer is effective in obtaining an elastic layer having a small compression set and quick recovery from deformation. However, as the elastic modulus of the elastic layer increases, its microrubber hardness also increases. That is, it has been extremely difficult to obtain an elastic layer having a high recovery rate from deformation while keeping the microrubber hardness of the elastic layer low. The present inventors conducted further studies to solve such problems. As a result, it is possible to use, as a constituent material of the elastic layer, a polyurethane elastomer into which a matrix-domain structure is introduced, which has a matrix having a structure capable of increasing the deformation recovery rate and a domain having a structure that contributes to suppressing an increase in microrubber hardness. was found to be effective in solving the above problems.
Hereinafter, the electrophotographic member and the like according to the present disclosure will be described in detail with reference to preferred embodiments.

<Electrophotographic materials>
1(a) and 1(b) are schematic circumferential cross-sectional views of two aspects of an electrophotographic member having a roller shape according to the present disclosure (hereinafter also referred to as an "electrophotographic roller"). be. An electrophotographic roller 1A shown in FIG. 1A has a conductive mandrel 2 and an elastic layer 3 covering the surface (outer peripheral surface) of the mandrel 2. As shown in FIG. In the electrophotographic roller 1B shown in FIG. 1B, a surface layer 4 is further formed on the surface of the elastic layer 3 opposite to the side facing the mandrel 2 (hereinafter also referred to as "outer surface"). have Note that the electrophotographic roller according to the present disclosure is not limited to these configurations, and may have, for example, an adhesive layer (not shown) between layers.

(mandrel)
The mandrel 2 preferably has conductivity in order to supply power to the surface of the electrophotographic member through the mandrel. The electrical resistance value of the mandrel is preferably lower than that of the elastic layer, and the volume resistivity of the mandrel is preferably 10 3 Ω·cm or less. The conductive mandrel can be appropriately selected from those known in the field of electrophotographic members, and is preferably made of a metal such as aluminum, an aluminum alloy, stainless steel, or iron. In addition, these metals may be plated with chromium, nickel, or the like in order to improve corrosion resistance and abrasion resistance. The shape of the mandrel may be any one selected from hollow (cylindrical) and solid (cylindrical). For example, it is possible to use a solid cylindrical mandrel made of a carbon steel alloy plated with nickel to a thickness of about 5 μm. The outer diameter of the cylindrical or columnar mandrel can be appropriately selected according to the image forming apparatus to be mounted.

(elastic layer)
The elastic layer 2 satisfies the following requirements (1-1) to (1-4).
Requirement (1-1): Containing a urethane elastomer, the urethane elastomer has a matrix-domain structure having a matrix and a plurality of domains dispersed in the matrix.
Requirement (1-2): Let A be a parameter indicating the viscoelastic term of the domain measured in a viscoelastic image of the cross section in the thickness direction of the elastic layer with a scanning probe microscope, and be measured in the viscoelastic image When the parameter indicating the viscoelastic term of the matrix is B, A<B. That is, the matrix-domain structure of the urethane elastomer is observed in the cross section in the thickness direction of the elastic layer according to the present disclosure. The elastic modulus of the urethane elastomer matrix observed in the cross section is greater than the elastic modulus of the domains.
Requirement (1-3): The elastic layer has a micro-rubber hardness of 20 or more and 50 or less at a temperature of 23°C.
Requirement (1-4): In the indentation test using a nanoindenter at 23 ° C. of the elastic layer, the Vickers indenter was indented at a load rate of 10 mN/30 seconds, the load was maintained at 10 mN for 60 seconds, and then the load was removed. The strain after 5 seconds of loading is 1 μm or less.
In the urethane elastomer according to the present disclosure, the matrix has the function of recovering from deformation, and the domains have the function of reducing the hardness of the urethane elastomer. By adopting such a urethane elastomer, the elastic layer according to the present disclosure has softness defined by the above requirement (1-3) and fast recovery from deformation defined by the above requirement (1-4). and is expressed.
On the other hand, common urethane elastomers also have a difference in elastic modulus between so-called hard segments and soft segments. However, it is believed that there was no urethane elastomer exhibiting a fast recovery rate from deformation as defined in requirement (1-4) while having flexibility as defined in requirement (1-3).

FIG. 2(a) is a partial cross-sectional view in the circumferential direction of the electrophotographic roller 1A according to one aspect of the present disclosure. FIG. 2(b) is a partial cross-sectional view of the electrophotographic roller 1A along the longitudinal direction of the mandrel 2. As shown in FIG.
2(a) and 2(b), the matrix 31 possessed by the urethane elastomer according to the present disclosure and a plurality of particles dispersed in the matrix 31 are observed in the cross section in the thickness direction of the elastic layer 3. and a domain 32 of .
The polyurethane elastomer has a matrix-domain structure having a matrix 31 and domains 32 dispersed in the matrix, as described above. The matrix 31 has a structure capable of increasing the deformation recovery speed, and the domain 32 has a structure that contributes to suppressing an increase in microrubber hardness. As a result, the matrix exhibits higher elasticity than the domains. 3(a) and 3(b) are explanatory diagrams of the deformation recoverability of the elastic layer 3 according to the present disclosure. As shown in FIG. 3(a), a plurality of domains 32 are dispersed in a matrix 31. FIG. Since the domains 32 have lower elasticity than the matrix 31, the domains 32 are preferentially deformed when the elastic layer 3 is compressed in the direction of arrow F as shown in FIG. 3(b). Therefore, even if the matrix 31 has high elasticity, the microrubber hardness of the elastic layer can be lowered. Moreover, when the elastic layer is released from compression, the thickness of the elastic layer can quickly return to the thickness before compression due to the elasticity of the matrix 31, which is a continuous phase.

(Micro rubber hardness of elastic layer)
The hardness of the elastic layer is 20 or more and 50 or less in terms of microrubber hardness. By setting the micro-rubber hardness to 50 or less, the nip width between the developing roller and the toner regulating member and the nip width between the charging roller and the photosensitive member are increased, and the contact pressure is not excessively increased. As a result, the toner on the developing roller is less likely to fuse to the developing roller, and the toner that has slipped through the cleaning member and adhered to the charging roller is less likely to fuse to the charging roller. Further, by setting the microrubber hardness to 20 or more, the mechanical strength is increased, and even when used in a long-life image forming apparatus, the edges of the elastic layer are less likely to be scraped off.
The microrubber hardness is determined as follows. When the length of the elastic layer in the longitudinal direction is L, there are two places where the micro rubber hardness is measured: the center in the longitudinal direction of the elastic layer, and L/4 from both ends of the elastic layer toward the center. It is a place. At each measurement location, the surface was measured with a micro rubber hardness tester (product name: MD-1capa; manufactured by Kobunshi Keiki Co., Ltd., push needle: type A (cylindrical shape, diameter 0.16 mm, height 0.5 mm, outer diameter 4 mm, inner diameter 1.5 mm), measurement mode: peak hold mode), and calculate the average value when micro rubber hardness is measured at a temperature of 23°C. This calculated average value is defined as the microrubber hardness in the present disclosure.

(Parameter indicating viscoelastic term)
The relative elastic modulus difference between matrix 31 and domains 32 can be measured by thinning the elastic layer and scanning probe microscopy (SPM/AFM). As the scanning probe microscope, for example, "S-Image" (trade name) manufactured by Hitachi High-Tech Science Co., Ltd. can be used. Examples of means for thinning include a sharp razor, a microtome, a focused ion beam method (FIB), and the like.
Sections are prepared at two locations, where L is the length of the elastic layer in the longitudinal direction, and at the center in the longitudinal direction of the elastic layer and L/4 from both ends toward the center of the elastic layer. As shown, a total of three sections are made from sections 41 to 43 in the thickness direction of the elastic layer. Further, the area that deforms when the electrophotographic member comes into contact with another member is mainly the thickness area from the outer surface of the elastic layer to a depth of 100 μm. Therefore, for the observation areas of cross sections 41 to 43, an arbitrary 50 μm square observation area is selected in the thickness area from the outer surface of each section to a depth of 100 μm, and the viscoelastic image is observed in a total of three observation areas. conduct.
The measurement mode of the viscoelastic image by SPM is the viscoelastic dynamic force mode (VE-DFM). name), manufactured by Hitachi High-Tech Science Co., Ltd., spring constant = 1.9 N/m), and the scanning frequency is 0.5 Hz. , is a mode in which a surface profile image is obtained while controlling the distance between the probe and the measurement sample so that the amplitude is constant.
After obtaining the viscoelastic image, 10 parameters indicating the viscoelastic term in each observation region are obtained in the matrix and the domain, and the average value is used as the parameter A indicating the viscoelastic term of the domain and the viscoelastic term of the matrix in the present disclosure. A parameter B indicating The unit of parameter A and parameter B is mV, and the greater the value, the higher the elasticity.
The ratio (A/B) between parameter A and parameter B is preferably 0.65 or less. The smaller the ratio A/B, the greater the difference in viscoelasticity between the matrix and the domains, making it easier to achieve both hardness and deformation recovery.

(Recovery from deformation)
In an indentation test using a nanoindenter at a temperature of 23° C., the elastic layer 3 was indented with a Vickers indenter at a load rate of 10 mN/30 seconds, maintained at a load of 10 mN for 60 seconds, and then unloaded. Distortion is 1 μm or less.
By setting the distortion to 1 μm or less after 5 seconds of unloading when measured under the above conditions, it is possible to suppress streak-like image defects when applied as a developing roller for a high-speed printer. This is because the deformation of the developing roller can be recovered to the size of one toner or less in a short period of time from when the high-speed printer is operated until the electrostatic latent image is developed. In addition, even when applied to a charging roller, since the recovery from deformation is fast, uneven discharge to the photoreceptor is less likely to occur, and streak-like image defects due to uneven charging of the photoreceptor can be prevented.
In the present disclosure, "Fischerscope HM2000" (trade name, manufactured by Fisher Instruments Co., Ltd.) is used as a nanoindenter, and measured values at a temperature of 23°C are employed. The indenter used for the measurement is a square pyramid Vickers indenter with a facing angle of 136°. Furthermore, when the length of the elastic layer in the longitudinal direction is L, there are three measurement positions in total: the center in the longitudinal direction of the elastic layer and the two positions of L/4 from both ends toward the center of the elastic layer. At each measurement location, the average value when measured using a nanoindenter is taken as the strain after 5 seconds of unloading in the present disclosure.

(elastic modulus of matrix)
The modulus of elasticity of the matrix 31 is preferably 2 MPa or more and 8 MPa or less. By setting the modulus of elasticity of the matrix to 2 MPa or more, the effect of the matrix as a spring is enhanced, and recovery from deformation can be accelerated. Further, by setting the elastic modulus of the matrix to 8 MPa or less, the hardness of the matrix is lowered, and the microrubber hardness of the elastic layer can be kept low.
The elastic modulus of the matrix can be measured by thinning the elastic layer and using a scanning probe microscope (SPM/AFM). As a scanning probe microscope, for example, "MFP-3D-Origin" (trade name) manufactured by Oxford Instruments Co., Ltd. can be used. Examples of means for thinning include a sharp razor, a microtome, a focused ion beam method (FIB), and the like.
Sections are prepared at two locations, where L is the length of the elastic layer in the longitudinal direction, and at the center in the longitudinal direction of the elastic layer and L/4 from both ends toward the center of the elastic layer. A total of 3 sections are made through the thickness of the elastic layer as shown. In addition, regarding the observation areas of cross sections 41 to 43, an arbitrary 50 μm square observation area is selected in the thickness area from the outer surface of each section to a depth of 100 μm, and phase images are observed in a total of three observation areas. conduct. The measurement mode of the phase image by SPM is assumed to be AM-FM. As the cantilever, a dynamic mode silicon cantilever such as "OMCL-AC-160TS" (trade name, manufactured by Olympus Corporation, spring constant=47.08 N/m) is used. Furthermore, the scanning frequency shall be 0.5 Hz.
After acquiring the phase image, the force curve is measured using SPM to measure the elastic modulus of the matrix. The force curve measurement mode is the contact mode, the Force Distance is 500 nm, and the Trigger Point is 0.01V. As for the cantilever, a dynamic mode silicon cantilever such as "OMCL-AC-160TS" (trade name, manufactured by Olympus Corporation, spring constant=47.08 N/m) is used in the same manner as described above. The scanning frequency is assumed to be 1 Hz.
The elastic modulus of the matrix was determined at 10 points in each observation area, and the average value was taken as the elastic modulus of the matrix in the present disclosure.

(cross-sectional area and number of domains)
The cross-sectional area and the number of polyurethane elastomer domains 32 observed in the cross section in the thickness direction of the elastic layer will be described.
Assuming that the length of the elastic layer in the longitudinal direction is L, three points are designated: the center in the longitudinal direction of the elastic layer and L/4 from both ends toward the center of the elastic layer. For each of these three cross-sections in the thickness direction of the elastic layer, when an observation area of 50 μm square is arbitrarily placed in a thickness area from the outer surface of the elastic layer to a depth of 100 μm, all three observation areas are It is preferable to satisfy the following requirement (2-1) and requirement (2-2).
Requirement (2-1): The ratio of the sum of cross-sectional areas of domains existing in the observation area to the area of the observation area is 15% or more and 45% or less.
Requirement (2-2): When calculating the cross-sectional area of each domain existing in the observation area, the number of domains having a cross-sectional area of 0.1% or more and 13.0% or less of the area of the observation area. , the ratio of the total number of domains existing in the observation area is 70% or more.
Regarding the above requirement (2-1), the microrubber hardness of the elastic layer can be kept low by setting the ratio of the sum of the cross-sectional areas of the domains to the area of the observation region to be 15% or more. In addition, by setting the ratio to 45% or less, recovery from deformation of the elastic layer can be accelerated.
Regarding the requirement (2-2), the number of domains having a cross-sectional area of 0.1 to 13.0% of the area of the observation area is 70% or more of the total number of domains in the observation area, so that the elastic layer The number of domains is ensured to be sufficiently large to be deformed when the is pressed. Therefore, the microrubber hardness of the elastic layer can be lowered. Moreover, since the number of large domains that are excessively deformed when a load is applied to the elastic layer is small, it is possible to prevent the microrubber hardness of the elastic layer from becoming too low.
Here, the cross-sectional area and the number of domains are obtained as follows. First, a section is prepared in the same manner as in the measurement of the modulus of elasticity of the matrix described above. Sections are prepared at two locations, where L is the length of the elastic layer in the longitudinal direction, and at the center in the longitudinal direction of the elastic layer and L/4 from both ends toward the center of the elastic layer. Sections are made exposing cross-sections 41, 42 and 43 through the full thickness of the elastic layer as shown. Next, an observation area of 50 μm square is set at an arbitrary position within the thickness area of each section from the outer surface of the elastic layer to a depth of 100 μm. Then, the cross-sectional area, number, and circularity of domains are measured for a total of three observation regions.

The cross-sectional area of domains in the observation area and the number of domains can be measured as follows. First, a cross section is observed using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning probe microscope (SPM/AFM). The obtained cross-sectional image is converted into a 256-gradation monochrome image using image processing software such as "ImageProPlus" (trade name, manufactured by MediaCybernetics). Next, binarization processing is performed using the above image processing software to obtain a binarized image. The binarization method is not particularly limited as long as the domain and matrix in the monochrome image can be discriminated. A method of setting a threshold value for binarization based on the
Next, for the binarized image, the count function of the image processing software is used to obtain the cross-sectional areas of domains present in the observation area and the number of domains. Note that the obtained binarized image for analysis may contain minute dots derived from noise. When analysis is performed using image processing software based on a binarized image in which such fine dots derived from noise are present, the dots derived from noise may also be counted as domains. Therefore, among the domains determined to be domains using the counting function, domains with a cross-sectional area of less than 0.05% with respect to a 50 μm square observation area are regarded as noise-derived domains and deleted from the data. is preferred.

(domain circularity)
Furthermore, the polyurethane elastomer domains observed in the cross section in the thickness direction of the elastic layer are the total number of domains present in the observation area, the number of domains having a degree of circularity of 0.60 or more and 0.95 or less. is preferably 70% by number or more.
A domain having a degree of circularity greater than a certain level is less likely to have anisotropy in the direction in which the shape of the domain recovers when the domain recovers from deformation. Further, since the number (proportion) of domains having a certain degree of circularity or more is large, the recovery from deformation of the elastic layer is less likely to be anisotropic. As a result, wrinkles due to the anisotropy of deformation recovery are less likely to occur in the elastic layer after recovery from deformation.
Here, the degree of circularity and the number of domains can be obtained by using the counting function of the image processing software at the same time as measuring the cross-sectional area and the number of domains.

(Material of elastic layer)
A polyurethane elastomer that can realize the elastic layer according to the present disclosure will be described. As previously mentioned, the polyurethane elastomer according to the present disclosure has a matrix-domain structure having a matrix 31 and domains 32 dispersed within the matrix. The matrix 31 has a structure capable of increasing the deformation recovery speed, and the domain 32 has a structure that contributes to suppressing an increase in microrubber hardness.
Such a polyurethane elastomer matrix 31 preferably has a polycarbonate structural unit represented by general formula (1) as a repeating structural unit. Furthermore, it is more preferable that the alkylene group having 3 to 9 carbon atoms represented by R ₁ in the repeating structural unit represented by general formula (1) has a branched structure.

（Ｒ_１は、炭素数３～９のアルキレン基示す。）

(R ₁ represents an alkylene group having 3 to 9 carbon atoms.)

In general, polyurethanes obtained by reacting polyols having a polycarbonate structure (polycarbonate polyols) with polyisocyanates exhibit high elasticity due to strong intermolecular forces between carbonate groups. Therefore, it is preferable as a constituent of the matrix 31 .
When R ₁ is an alkylene group having 3 to 9 carbon atoms, incompatibility with the domain containing the polyether of the repeating structural unit represented by the general formula (2) described later is ensured, and the matrix and the domain are separated. Clear phase separation can be achieved. Thereby, the two functions of softness and fast recovery from deformation of the polyurethane elastomer according to the present disclosure can be exhibited more reliably.
In addition, when R ₁ contains an alkylene group having a branched structure with 3 to 9 carbon atoms, the intermolecular force between carbonate groups can be moderately suppressed, and the matrix can be prevented from becoming excessively highly elastic.
Examples of R ₁ include -(CH ₂ ) _m - (m=3 to 9), -CH ₂ C(CH ₃ ) ₂ CH ₂ -, -CH ₂ CH(CH ₃ )CH ₂ -, -(CH ₂ ) ₂ CH(CH ₃ )(CH ₂ ) ₂ — and the like. These can be used singly or in combination of two or more.
The number average molecular weights of polyols and the like described later, including the number average molecular weight of the polycarbonate, can be calculated by the following formula using the hydroxyl value (mgKOH/g) and the valence. For example, a polyether polyol having a hydroxyl value of 56.1 mgKOH/g and a valence of 2 can be calculated to have a number average molecular weight of 2,000.
Number average molecular weight = 56.1 x 1000 x valence/hydroxyl value The elastic modulus of the matrix can be adjusted by, for example, increasing the crosslink density using a polyisocyanate trimer compound or multimer compound. . Normally, increasing the elastic modulus also increases the micro-rubber hardness of the elastic layer, but in the present disclosure, a plurality of low-elasticity domains are dispersed in the matrix, so excessive increase in hardness can be suppressed.

Domain 32 preferably contains a polyether structural unit represented by general formula (2) as a repeating structural unit. Furthermore, the C3-5 alkylene group represented by R ₂ in the structural unit represented by general formula (2) preferably has a branched structure.

（Ｒ_２は、炭素数３～５のアルキレン基を示す。）

(R ₂ represents an alkylene group having 3 to 5 carbon atoms.)

Polyethers are generally preferred as components of the domains because they exhibit low elastic moduli due to weak intermolecular forces between ether groups.
By containing an alkylene group having 3 to 5 carbon atoms, incompatibility with a urethane elastomer having a polycarbonate structural unit represented by general formula (1) is ensured, and the matrix and domains are preferably phase-separated clearly. .
Examples of R ₂ include -(CH ₂ )m-(m=3 to 5), -CH ₂ CH(CH ₃ )-, -CH ₂ C(CH ₃ ) ₂ CH ₂ -, -CH ₂ CH( CH ₃ )CH ₂ —, —(CH ₂ ) ₂ CH(CH ₃ )CH ₂ — and the like. These can be used singly or in combination of two or more.
The number average molecular weight of the polyether structural unit represented by general formula (2) is preferably 1,000 or more and 50,000 or less. More preferably, it is 1200 or more and 30000 or less.
When the number average molecular weight is 1000 or more, incompatibility with the urethane elastomer containing the polycarbonate structural unit represented by the general formula (1) is ensured, and the phase separation between the matrix and the domain becomes clear, which is preferable. Further, when the number average molecular weight is 50,000 or less, it is preferable because domains are easily formed and the phase separation state is stabilized.
The ratio of the total cross-sectional area of the domains can be adjusted, for example, by the blending ratio of the urethane elastomer containing the polycarbonate structural unit of general formula (1) in the matrix and the polyether structural unit of general formula (2) in the domain. Increasing the compounding ratio of the polyether structural unit of general formula (2) increases the ratio of the total cross-sectional area of the domains. However, if the compounding ratio of the polyether structural unit of general formula (2) is excessively increased, the matrix and domain may be reversed and the polyether structural unit of general formula (2) may become the main component of the matrix. Also, the cross-sectional area of the domain can be increased, for example, by increasing the number average molecular weight of the polyether structural unit of general formula (2).
The chemical structures of the components contained in the matrix and domains are analyzed using, for example, a spectroscopic analyzer such as an AFM infrared spectrometer, a microscopic infrared spectrometer, a microscopic Raman spectrometer, or a mass spectrometer. can do.

(Method for producing polyurethane elastomer)
An example of the method for producing the above polyurethane elastomer includes a method having the following steps (i) to (iii).
Step (i) reacting a first polyether having at least two isocyanate groups with a first polycarbonate polyol having at least two hydroxyl groups to obtain a urethane reactive emulsifier having at least two hydroxyl groups; .
Step (ii) obtaining a dispersion of droplets containing at least a portion of a urethane reactive emulsifier dispersed in a second polycarbonate polyol.
Step (iii) preparing an elastic layer-forming mixture containing the dispersion obtained in step (ii) and a polyisocyanate having at least two isocyanate groups; reacting a reactive emulsifier, said second polycarbonate polyol, and said polyisocyanate;

Each step of the above manufacturing method will be described with reference to FIG.
In step (i), a first polyether 51 having at least two isocyanate groups and a first polycarbonate polyol 52 having at least two hydroxyl groups are mixed. A urethane reactive emulsifier 53 having at least two hydroxyl groups is obtained by reacting the isocyanate groups and hydroxyl groups in the mixture in the presence of a catalyst and linking them via urethane bonds.
In step (ii), the urethane reactive emulsifier 53 obtained in step (i) is dispersed in the second polycarbonate polyol 55 . The segments derived from the first polyether 51 contained in the urethane reactive emulsifier 53 are incompatible with the second polycarbonate polyol 55 and form droplets 54 . On the other hand, via the segment derived from the first polycarbonate polyol 52 contained in the urethane reactive emulsifier 53, in the second polycarbonate polyol 55, the first polyol constituting part of the urethane reactive emulsifier Droplets 54 containing ether-derived segments are uniformly and stably dispersed. As a result, a dispersion is obtained in which droplets 54 containing segments derived from the first polyether 51 of the urethane reactive emulsifier 53 are dispersed in the second polycarbonate polyol 55 . For the sake of explanation, the step (i) and the step (ii) are described separately, but these steps may be a continuous series of steps.

In step (ii), the second polycarbonate polyol 55 for dispersing the droplets 54 is the unreacted product of the first polycarbonate polyol used in step (i) with the first polyether. can. That is, in step (i), by using an excessive amount of the first polycarbonate polyol with respect to the first polyether, the first polycarbonate polyol with excess urethane reactive emulsifier 53 described in step (ii), That is, a dispersion obtained by dispersing in the second polycarbonate polyol 55 can be obtained. Even when the first polycarbonate polyol is used in an excessive amount, a polycarbonate polyol (second polycarbonate polyol) can be additionally added as a dispersion medium for the urethane-reactive emulsifier. In this case, the additional polycarbonate polyol may be of the same chemical composition as or different from the first polycarbonate polyol used in step (i).

On the other hand, in step (i), the first polycarbonate polyol and the first polyether are reacted in equal amounts, and when all the first polycarbonate polyol is consumed, in step (ii), a new A dispersion is prepared using a polycarbonate polyol as the second polycarbonate polyol. Also in this case, the polycarbonate polyol used as the second polycarbonate polyol may or may not have the same chemical composition as the first polycarbonate polyol.

Finally, in step (iii), an elastic layer-forming mixture containing the dispersion prepared in step (ii) and polyisocyanate 56 having at least two isocyanate groups is prepared. Next, the terminal hydroxyl groups of the urethane reactive emulsifier 53, the hydroxyl groups of the second polycarbonate polyol 55, and the isocyanate groups of the polyisocyanate 56 in the elastic layer-forming mixing portion are reacted. By forming a network structure via urethane bonds in this manner, the elastic layer-forming mixture is cured to obtain the polyurethane elastomer according to the present disclosure. The polyurethane elastomer 500 thus obtained contains a urethane elastomer in which the domain 32 containing polyether derived from the first polyether 51 has polycarbonate derived from the first polycarbonate polyol 52 and the second polycarbonate polyol 55. It has a matrix-domain structure dispersed in a matrix 31 . Also, the domain 32 is mainly composed of a polyether structure portion, and the interior of the domain can be substantially free of crosslinked structures. In other words, domains 32 may exist in the matrix in a substantially liquid state. This allows the domains to have a low elastic modulus in the polyurethane elastomers of the present disclosure.

Furthermore, the domains are not simply confined in the matrix in the liquid portion, but are chemically bonded to the matrix by urethane bonds at the boundary between the domains and the matrix. As such, the recovery from deformation of the domains when the load applied to the polyurethane elastomer is removed can be coupled with the recovery from deformation of the matrix. That is, the substantially liquid domain has substantially no crosslinked structure inside. Therefore, it is difficult for the domain deformed by applying a load to the polyurethane elastomer to recover from the deformation autonomously. However, in the polyurethane elastomer according to the present disclosure, the domains are chemically bonded to the matrix at the interface with the matrix, so that the domains can recover from deformation together with the deformation recovery of the matrix. As a result, stable deformation (deformation amount) and stable recovery from the deformation are achieved even when the polyurethane elastomer is repeatedly subjected to load loading and unloading.

The above steps (i) to (ii) are steps for stably dispersing polyether, which originally has low compatibility and is difficult to disperse stably and uniformly, in polyol. That is, a first polyether 51 is reacted with a first polycarbonate polyol 52 to form a urethane reactive emulsifier 53 . This is a step of obtaining a dispersion in which the polyether segments derived from the first polyether 51 are stably and uniformly dispersed in the second polycarbonate polyol. As a result, it is possible to produce a polyurethane elastomer in which domains 32 with a high degree of circularity and a relatively uniform size distribution are dispersed in the polyurethane 31 as a matrix.
As another method of mixing materials with low compatibility, for example, there is a method of mixing and dispersing with a high shearing force. However, in this method, as a result of applying a high shearing force to the polyether, the shape of the domains becomes distorted, the degree of circularity decreases, and the sizes of the domains may become uneven. In addition, the dispersed state is also unstable, and the aggregation of the domains progresses in a relatively long period of time. In addition, incompatibility between the polyether and the polycarbonate polyol is not ensured, and phase separation between the matrix and the domains of the resulting urethane elastomer becomes unclear. Therefore, it is difficult to obtain a polyurethane elastomer that provides an elastic body that is flexible and has excellent deformation recovery properties according to the present disclosure.

The first polyether is a polyether having at least two isocyanate groups and a repeating structural unit represented by general formula (2). The first polyether is, for example, a step of reacting a polyether polyol having at least two hydroxyl groups and a repeating structural unit represented by the general formula (2) with a polyisocyanate having at least two isocyanate groups. can be obtained by
Examples of polyether polyols include alkylene structure-containing polyether-based polyols such as polypropylene glycol, polytetramethylene glycol, copolymers of tetrahydrofuran and neopentyl glycol, and copolymers of tetrahydrofuran and 3-methyltetrahydrofuran. Examples include random or block copolymers of polyalkylene glycol. These can be used singly or in combination of two or more.
Among polyether polyols, amorphous polyether polyols are preferable from the viewpoint of being incompatible with the second polycarbonate polyol and being able to achieve low hardness.
More preferably, it contains at least one selected from polypropylene glycol, a copolymer of tetrahydrofuran and neopentyl glycol, and a copolymer of tetrahydrofuran and 3-methyltetrahydrofuran.
The number average molecular weight of the polyether polyol is preferably 1,000 or more and 50,000 or less. More preferably, it is 1200 or more and 30000 or less. A number-average molecular weight of 1,000 or more is preferable because the incompatibility with the polycarbonate polyol is ensured and the phase separation between the matrix and the domains of the obtained urethane elastomer becomes clear. Further, when the number average molecular weight is 50,000 or less, it is preferable because domains are easily formed and the phase separation state is stabilized.

Examples of polyisocyanates to be reacted with polyether polyols include pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, or these poly Isocyanate trimer compounds (isocyanurates), polymer compounds, allophanate-type polyisocyanates, biuret-type polyisocyanates, water-dispersed polyisocyanates, and the like can be mentioned. These polyisocyanates can be used alone or in combination of two or more.
Among polyisocyanates, a bifunctional isocyanate having two isocyanate groups is preferred because of its high compatibility with the first polyether and ease of adjusting physical properties such as viscosity. More preferably, it contains at least one selected from hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate.
In the step of reacting polyether polyol and polyisocyanate, the isocyanate index is preferably in the range of 1.2 to 5.0. When the isocyanate index is within this range, it is possible to reduce the amount of the first polyether-derived component that remains without forming a network structure, and to suppress the exudation of the liquid substance from the urethane elastomer. The isocyanate index indicates the ratio ([NCO]/[OH]) of the number of moles of isocyanate groups in the isocyanate compound to the number of moles of hydroxyl groups in the polyol compound.
The first polyether obtained by the reaction of polyether polyol and polyisocyanate has a structure in which hydroxyl groups and isocyanate groups are linked via urethane bonds. The number average molecular weight is preferably 1,000 or more and 50,000 or less. More preferably, it is 1200 or more and 30000 or less.

The first polycarbonate polyol is a polycarbonate polyol having at least two hydroxyl groups and a repeating structural unit represented by general formula (1). Examples of the first polycarbonate polyol include reaction products of polyhydric alcohols and phosgene, ring-opening polymers of cyclic carbonates (alkylene carbonates and the like), and the like.
Examples of polyhydric alcohols include propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5 - pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, tri Examples include methylolethane, cyclohexanediols (1,4-cyclohexanediol, etc.), sugar alcohols (xylitol, sorbitol, etc.), and the like.
Alkylene carbonates include, for example, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate and the like.
The number average molecular weight of the first polycarbonate polyol is preferably 500 or more and 10,000 or less. More preferably, it is 700 or more and 8000 or less. When the number average molecular weight is 500 or more, the incompatibility with the domain containing the polyether of the repeating structural unit represented by the general formula (2) is ensured, and the phase separation between the matrix and the domain can be made clearer. . Also, by setting the number average molecular weight to 10,000 or less, it is possible to prevent an excessive increase in the viscosity of the first polycarbonate polyol.
As the second polycarbonate polyol used in step (ii), the polycarbonate polyols listed above for the first polycarbonate polyol can be used. As described above, the first polycarbonate polyol and the second polycarbonate polyol may have the same chemical composition, or different ones may be used.

As the polyisocyanate 56 having at least two isocyanate groups used in step (iii), the same polyisocyanates as those exemplified above as the raw material of the first polyether can be used. These polyisocyanates can be used alone or in combination of two or more.
As the polyisocyanate 56, from the viewpoint of increasing the elastic modulus of the matrix, among the polyisocyanates exemplified above, a polyisocyanate trimer compound (isocyanurate) or polymer compound, allophanate-type polyisocyanate, buret It preferably comprises a polyisocyanate having at least 3 isocyanate groups, such as a polyisocyanate of the type. More preferably, it contains any one of a pentamethylene diisocyanate trimer compound (isocyanurate), a hexamethylene diisocyanate trimer compound (isocyanurate), and a diphenylmethane diisocyanate polymer compound.

As the catalyst, conventionally known urethanization catalysts and isocyanurate catalysts (isocyanate trimerization catalysts) can be used. One of these may be used alone, or a mixture thereof may be used.
Examples of urethanization catalysts include tin-based urethanization catalysts such as dibutyltin dilaurate and stannous octoate, triethylenediamine, tetramethylguanidine, pentamethyldiethylenetriamine, diethylimidazole, tetramethylpropanediamine, N, N, N Examples include amine-based urethanization catalysts such as '-trimethylaminoethylethanolamine and 1,4-diazabicyclo[2.2.2]octane-2-methanol. One of these may be used alone, or a mixture thereof may be used.
Examples of isocyanurate catalysts include metal oxides such as Li ₂ O and (Bu ₃ Sn) ₂ O, hydride compounds such as NaBH ₄ , NaOCH ₃ , KO-(t-Bu), borates, and the like. alkoxide compounds, N(C ₂ H ₅ ) ₃ , N(CH ₃ ) ₂ CH ₂ C ₂ H ₅ , amine compounds such as 1,4-ethylenepiperazine (DABCO), HCOONa, Na ₂ CO ₃ , PhCOONa /DMF, CH ₃ COOK, (CH ₃ COO) ₂ Ca, alkaline soap, alkaline carboxylate salt compounds such as naphthenate, alkaline formate compounds, ((R) ₃ —NR′OH)—OCOR”, etc. and quaternary ammonium salt compounds of.In addition, the combination catalyst (cocatalyst) used as the isocyanurate catalyst includes, for example, amine/epoxide, amine/carboxylic acid, amine/alkyleneimide, etc.These isocyanurates The conversion catalyst and combination catalyst may be used alone or in combination.

In the production method according to the present disclosure, a chain extender (polyfunctional low-molecular-weight polyol) may be used as necessary. Examples of chain extenders include glycols having a number average molecular weight of 1000 or less. Examples of glycols include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD), 1,6-hexanediol ( 1,6-HD), 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylylene glycol (terephthalyl alcohol), triethylene glycol and the like. Examples of chain extenders other than glycol include polyhydric alcohols having a valence of 3 or more. Examples of trihydric or higher polyhydric alcohols include trimethylolpropane, glycerin, pentaerythritol and sorbitol. These may be used alone or in combination.
Additives such as pigments, plasticizers, waterproofing agents, antioxidants, conductive agents, ultraviolet absorbers, and light stabilizers may also be used together as necessary.

(Manufacturing method of elastic layer)
The elastic layer can be formed, for example, by carrying out the reaction of step (iii) in the method for producing a polyurethane elastomer on the surface of the mandrel.
Specifically, for example, there is a method of curing the elastic layer-forming mixture containing the dispersion prepared in the step (ii) and a polyisocyanate having at least two isocyanate groups on the peripheral surface of the mandrel. be done. That is, the elastic layer according to the present disclosure can be produced by, for example, a method including the following steps (2-i) to (2-iv).
Step (2-i) reacting a first polyether having at least two isocyanate groups with a first polycarbonate polyol having at least two hydroxyl groups to produce a urethane reactive emulsifier having at least two hydroxyl groups; the step of obtaining
Step (2-ii) obtaining a dispersion in which droplets containing at least a portion of the urethane reactive emulsifier are dispersed in a second polycarbonate polyol;
Step (2-iii) a step of mixing the dispersion and a polyisocyanate having at least two isocyanate groups to obtain a mixture for forming an elastic layer, and Step (2-iv) on the surface of the mandrel a step of reacting the urethane reactive emulsifier in the elastic layer-forming mixture, the second polycarbonate polyol, and the polyisocyanate to obtain the elastic layer. manufacturing method.
As a method for curing the elastic layer forming mixture on the surface of the mandrel, for example, a cylindrical pipe, a piece for holding the mandrel, and a mold in which the mandrel is disposed, and the elastic layer is formed on the mold. A method of injecting the material of and heat curing (cast molding method) can be used. Alternatively, a method may be used in which the elastic layer forming mixture is applied to the surface of the mandrel to form a coating film, and the coating film is heated and cured.

(Surface layer)
A surface layer may be provided on the surface of the elastic layer, if necessary. Materials for forming the surface layer include resins, natural rubbers, and synthetic rubbers. A thermosetting resin or a thermoplastic resin can be used as the resin. In particular, fluorine resins, polyamide resins, acrylic resins, polyurethane resins, silicone resins, or butyral resins are preferable as resins, since the viscosity of the paint can be easily controlled. These resins can be used alone or in combination of two or more. It may also be a copolymer.
A conductive agent can be added to the surface layer to adjust the electrical resistance of the electrophotographic roller. The volume resistivity of the surface layer can be adjusted with an ionic conductive agent or an electronic conductive agent.

Examples of ion conductive agents include the following. Inorganic ionic substances such as lithium perchlorate, sodium perchlorate and calcium perchlorate. Cationic surfactants such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, trioctylpropylammonium bromide, and modified aliphatic dimethylethylammonium ethosulfate. Zwitterionic surfactants such as lauryl betaine, stearyl betaine, dimethylalkyl lauryl betaine. Quaternary ammonium salts such as tetraethylammonium perchlorate, tetrabutylammonium perchlorate and trimethyloctadecyl ammonium perchlorate. organic acid lithium salts such as lithium trifluoromethanesulfonate; One of these can be used alone or in combination of two or more.

Examples of electronic conductive agents include the following. Fine particles and fibers of metals such as aluminum, palladium, iron, copper, and silver. Conductive metal oxides such as titanium oxide, tin oxide and zinc oxide. Composite particles obtained by surface-treating the surfaces of the metal-based fine particles, fibers, or metal oxides by electrolytic treatment, spray coating, or mixing and shaking. Carbon powder such as furnace black, thermal black, acetylene black, ketjen black, PAN (polyacrylonitrile) carbon, and pitch carbon.

The surface layer can also contain other particles. Other particles may include insulating particles. Examples of insulating particles include the following. Polyamide resins, silicone resins, fluorine resins, (meth)acrylic resins, styrene resins, phenol resins, polyester resins, melamine resins, urethane resins, olefin resins, epoxy resins, copolymers, modified products and derivatives thereof. Ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR ), rubber such as epichlorohydrin rubber, polyolefin thermoplastic elastomer, urethane thermoplastic elastomer, polystyrene thermoplastic elastomer, fluororubber thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer, polybutadiene thermoplastic elastomer , ethylene vinyl acetate thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, chlorinated polyethylene thermoplastic elastomer. Among these, (meth)acrylic resins, styrene resins, urethane resins, fluororesins, and silicone resins are particularly preferred.

The materials that make up these surface layers can be dispersed using conventionally known dispersing devices that utilize sand mills, paint shakers, dyno mills, or pearl mill beads. The method of applying the obtained dispersion is not particularly limited, but the dipping method is preferable because the operation is simple.

<Electrophotographic image forming apparatus>
FIG. 6 shows a schematic configuration of an example of an electrophotographic image forming apparatus having an electrophotographic member according to one embodiment of the present disclosure.
In FIG. 6, the image forming apparatus includes a photosensitive member 61, a charging device, a latent image forming device, a developing device, a transfer device, a cleaning device, and a fixing device.
Photoreceptor 61 is a rotating drum having a photosensitive layer on a conductive substrate. The photosensitive member 61 is rotationally driven in the direction of the arrow at a predetermined peripheral speed (process speed).
The charging device has a function of charging the photoreceptor 61 and has a contact-type charging roller 62 that is arranged in contact with the photoreceptor 61 by being brought into contact with the photoreceptor 61 with a predetermined pressing force. The charging roller 62 rotates in the direction of the arrow as the photosensitive member 61 rotates. The charging roller 62 charges the photosensitive member 61 to a predetermined potential by applying a predetermined DC voltage from the charging power source 63 .
A latent image forming device (not shown) performs exposure to form an electrostatic latent image on the photoreceptor 61 . An exposure device such as a laser beam scanner is used as the latent image forming device. The latent image forming device forms an electrostatic latent image by irradiating a uniformly charged photosensitive member 61 with exposure light 64 corresponding to image information.
The developing device has a function of developing a toner image, and has a developing roller 65 arranged in proximity to or in contact with the photoreceptor 61 . The developing roller 65 forms a toner image on the photoreceptor 61 by developing the electrostatic latent image by reversal development using toner that has been electrostatically processed to have the same polarity as the charge polarity of the photoreceptor 61 .
The transfer device has a function of transferring the developed toner image onto the recording material P, and has a contact type transfer roller 66 . The transfer roller 66 rotates in the direction of the arrow as the photosensitive member 61 rotates, and transfers the toner image from the photosensitive member 61 to the recording material P such as plain paper. Note that the transfer material P is conveyed in the direction of the arrow by a paper feeding system (not shown) having a conveying member.
The cleaning device has a function of collecting transfer residual toner on the photoreceptor 61 , and has a blade-type cleaning member 68 and a collection container 69 . After the toner image is transferred onto the recording material P, the cleaning device mechanically scrapes off and collects the transfer residual toner remaining on the photosensitive member 61 .
Here, it is possible to omit the cleaning device by adopting a development simultaneous cleaning method in which the transfer residual toner is recovered by the developing device.
The fixing device has a function of fixing the toner image, and is composed of a fixing belt 67 having a heated roll. The material P is discharged out of the machine.
In the image forming apparatus, the electrophotographic member described above can be suitably used as the charging roller 62 and the developing roller 65 .

<Process cartridge>
FIG. 7 shows a schematic configuration of one form of a process cartridge according to one form of the present disclosure. The process cartridge integrates the photoreceptor 71, charging roller 72, developing roller 73, and cleaning member 74, and is detachably attached to the image forming apparatus. The process cartridge includes the electrophotographic member according to one embodiment of the present disclosure, and the electrophotographic member can be suitably used as the charging roller 72 and the developing roller 73 in particular.

An embodiment of the present disclosure will be described more specifically below with reference to examples. However, the present disclosure is not limited to the examples below.

<Example 1>
(Preparation of Elastic Layer-Forming Mixture)
Polypropylene glycol (trade name: PREMINOL S 4013F, manufactured by AGC Corporation) 20.1 parts by mass and polypropylene glycol (trade name: Uniol D-4000, manufactured by NOF Corporation) 19.2 parts by mass, xylylene diisocyanate (XDI) (manufactured by Tokyo Chemical Industry Co., Ltd.) 1,4-diazabicyclo [2.2.2] octane-2-methanol (trade name: RZETA, manufactured by Tosoh Corporation) 500 ppm as a curing catalyst was added to 2.5 parts by mass, and 100 A polyether having two isocyanate groups was synthesized by stirring for 4 hours in a closed mixer adjusted to °C.
50.3 parts by mass of polycarbonate diol (trade name: Duranol G3452, manufactured by Asahi Kasei Corporation) was mixed with this. After that, by stirring for another 2 hours in a closed mixer adjusted to 100° C., a urethane reactive emulsifier having two hydroxyl groups was synthesized, and a dispersion in which droplets containing the urethane reactive emulsifier were dispersed in polycarbonate diol was obtained. Obtained.
To this dispersion, 0.8 parts by mass of xylylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter sometimes referred to as "XDI"), polyisocyanate (trade name: Millionate MR-200, manufactured by Tosoh Corporation, hereinafter, "MR-200" may be described) 5.2 parts by mass, ion conductive agent (trade name CIL-542: manufactured by Nihon Carlit Co., Ltd., hereinafter sometimes referred to as "CIL") 1.8 Parts by mass were added and stirred for 2 minutes at a revolution speed of 1600 rpm with a revolution type vacuum defoaming mixer to obtain a mixture for forming an elastic layer.

(Production of electrophotographic roller)
A mandrel made of SUS304 with a diameter of 6 mm and a length of 250 mm was coated with a primer (trade name: Metalloc N-33, manufactured by Toyo Kagaku Kenkyusho Co., Ltd.) and baked at 130° C. for 30 minutes.
Next, this mandrel was placed concentrically in a cylindrical mold having an inner diameter of 11.5 mm, and the elastic layer-forming mixture was injected into the cylindrical mold preheated to 130° C. over 10 seconds.
After the cylindrical mold was heated at 130° C. for 1 hour, it was removed from the mold and further aged at 80° C. for 2 days to obtain an elastic layer. Further, an electrophotographic roller having a length of 225 mm and an elastic layer thickness of 2.0 mm was obtained by removing the ends of the elastic layer. The obtained electrophotographic roller was evaluated as follows.

・Evaluation method for electrophotographic rollers (Evaluation 1: matrix (may be indicated as “M” in Table 4-1) and domain (may be indicated as “D” in Table 4-1) confirmation and analysis)
Sections were made from the electrophotographic roller using a microtome. Sections are prepared at a total of three locations: the center in the longitudinal direction of the elastic layer and two locations of L/4 from both ends toward the center of the elastic layer, where L is the length of the elastic layer in the longitudinal direction. , slices were made in the thickness direction of the elastic layer.
Mapping measurement was performed using a three-dimensional microscopic laser Raman spectrometer (trade name: Nanofinder 30, manufactured by Tokyo Instruments Co., Ltd.). The measurement mode was EM (Electron Multiplying), 60×60 points were measured at intervals of 500 nm, and integrated images of 0 to 400 cm −1 were obtained. From the integral image obtained, it was confirmed that the elastic layer had a matrix and a plurality of domains dispersed in the matrix. In addition, the matrix and domains were clearly phase-separated.
Next, the Raman spectra of the matrix and domain parts were measured from the integrated image. The measurement was carried out with a light source of Nd:YVO4 (wavelength of 532 nm), a laser intensity of 240 μW, an objective lens of 100×, a diffraction grating of 300 gr/mm, a pinhole diameter of 100 μm, an exposure time of 30 seconds, and an integration count of 1. rice field. From the obtained Raman spectrum, it was confirmed that the matrix contained a structure derived from polycarbonate urethane and the domain contained a structure derived from polypropylene glycol (in Table 4-1, sometimes referred to as "PPG"). did.

(Evaluation 2: Measurement of micro rubber hardness)
A micro rubber hardness tester (trade name: MD-1capa, manufactured by Kobunshi Keiki Co., Ltd.) was used to measure the micro rubber hardness of the elastic layer. In the measurement, the electrophotographic roller was left in an environment at a temperature of 23° C. for 24 hours or more, and the measurement was performed using a measuring device placed in the same environment. A type A (0.50 mm height, 0.16 mm diameter, cylindrical) indenter was used, and the peak hold mode was used as the measurement mode.
When the length of the elastic layer in the longitudinal direction is L, there are two places where the micro rubber hardness is measured: the center in the longitudinal direction of the elastic layer, and L/4 from both ends of the elastic layer toward the center. It is a place. An average value was calculated when the microrubber hardness was measured at each measurement location at a temperature of 23°C.

(Evaluation 3: Measurement of parameter indicating viscoelasticity term)
Sections were made from the electrophotographic roller using a microtome. Sections are prepared at a total of three locations: the center in the longitudinal direction of the elastic layer and two locations of L/4 from both ends toward the center of the elastic layer, where L is the length of the elastic layer in the longitudinal direction. , slices were made in the thickness direction of the elastic layer.
Select an arbitrary 50 μm square observation area in the thickness area from the outer surface of each section to a depth of 100 μm, and use a scanning probe microscope (trade name: S-Image, SII Nanotechnology) in a total of three observation areas. Co., Ltd.) was used to measure the viscoelastic image. The measurement mode of the viscoelastic image was set to VE-DFM. As the cantilever, “SI-DF3” (trade name, manufactured by Hitachi High-Tech Science Co., Ltd., spring constant=1.9 N/m) was used. Furthermore, the scanning frequency was set to 0.5 Hz.
From the obtained viscoelastic image, 10 parameters indicating the viscoelastic term in each observation area are calculated for the matrix and the domain. Parameter B was determined.

(Evaluation 4: Measurement of deformation recovery of elastic layer)
The deformation recovery property of the elastic layer was evaluated by an indentation test using a nanoindenter (trade name: HM2000, manufactured by Fisher Instruments Co., Ltd.) at a temperature of 23°C. In the measurement, the electrophotographic roller was left in an environment at a temperature of 23° C. for 24 hours or more, and the measurement was performed using a measuring device placed in the same environment.
The measurement is performed at a total of three locations: the center in the longitudinal direction of the elastic layer and two locations of L/4 from both ends toward the center of the elastic layer, where L is the length of the elastic layer in the longitudinal direction. In the indentation test, the elastic layer was indented with a Vickers indenter (square pyramid type, facing angle 136°) at a load rate of 10 mN/30 seconds, and the load was maintained at 10 mN for 60 seconds. After that, when the load was unloaded, the strain was measured at each measurement point 5 seconds after the load was unloaded, and the average value was calculated.

(Evaluation 5: Elastic modulus of matrix)
Sections were made from the electrophotographic roller using a microtome. Sections are prepared at a total of three locations: the center in the longitudinal direction of the elastic layer and two locations of L/4 from both ends toward the center of the elastic layer, where L is the length of the elastic layer in the longitudinal direction. , slices were made in the thickness direction of the elastic layer.
An arbitrary 50 μm square observation area was selected in the thickness area from the outer surface of each section to a depth of 100 μm. Phase images were observed in a total of three observation areas using a scanning probe microscope (trade name: MFP-3D-Origin, manufactured by Oxford Instruments). The phase image measurement mode was AM-AFM. As the cantilever, "OMCL-AC-160TS" (trade name, manufactured by Olympus Corporation, spring constant = 47.08 N/m) was used. Furthermore, the scanning frequency was set to 0.5 Hz.
The elastic modulus of the matrix was obtained from the obtained phase image by measuring the force curve using the scanning electron microscope. The force curve measurement mode was contact mode, Force Distance was 500 nm, and Trigger Point was 0.01V. As the cantilever, "OMCL-AC-160TS" (trade name, manufactured by Olympus Corporation, spring constant = 47.08 N/m) was used. Furthermore, the scanning frequency was set to 1 Hz. For each observation area, the elastic modulus of the matrix was determined at 10 points, and the average value was calculated.

(Evaluation 6: Measurement of cross-sectional area and number of domains)
Sections were made from the electrophotographic roller using a microtome. Sections are prepared at a total of three locations: the center in the longitudinal direction of the elastic layer and two locations of L/4 from both ends toward the center of the elastic layer, where L is the length of the elastic layer in the longitudinal direction. , a section in which the cross section in the entire thickness direction of the elastic layer was exposed was prepared.
A square observation area with a side of 50 μm was placed at an arbitrary position in the thickness area of each section from the outer surface of the elastic layer to a depth of 100 μm. Then, viscoelastic images were measured in a total of three observation regions using a scanning probe microscope (trade name: S-Image, manufactured by SII Nanotechnology Co., Ltd.).
The measurement mode of the viscoelastic image was a micro viscoelastic dynamic force mode (VE-DFM). As the cantilever, a silicon micro cantilever for DMF (SI-DF3, manufactured by Hitachi High-Tech Science Co., Ltd. , spring constant=1.9 N/m), and the scanning frequency was 0.5 Hz.
The obtained cross-sectional image was converted into a 256-gradation monochrome image using image processing software (trade name: ImageProPlus, manufactured by MediaCybernetics), and then binarized to obtain a binarized image for analysis. The threshold for binarization was determined based on the Otsu algorithm described in Non-Patent Document 1 from the luminance distribution of the monochrome image.
From the obtained binarized image, the cross-sectional area of the domain and the number of domains were calculated using the counting function of the image processing software. However, among those determined to be domains by the counting function, domains having a cross-sectional area of less than 0.05% with respect to the observation area of 50 μm square were regarded as domains caused by noise and were deleted from the data. Then, the ratio (%) of the sum of the cross-sectional areas of the domains in each observation area to the area of the observation area was calculated. Also, among the domains in each observation area, the number of domains whose cross-sectional area is 0.1% or more and 13.0% or less of the area of the observation area is obtained, and the ratio (% ).

(Evaluation 7: Measurement of Circularity and Number of Domains)
From the binary image obtained in Evaluation 6, the circularity of the domain was calculated using the count function of the image processing software. However, in the same manner as in Evaluation 6, noise-derived domains were deleted from the data. Then, among the domains in each observation area, the number of domains with a circularity of 0.60 or more and 0.95 or less was counted, and the ratio (%) to the total number of domains in each observation area was calculated.

(Evaluation 8: Evaluation of streak-like image defects)
A color laser printer (trade name: LBP7700C, manufactured by Canon Inc.) and a process cartridge incorporating an electrophotographic roller as a developing roller were immersed in an environment of temperature 23°C and humidity 50% RH for 24 hours, and then image evaluation was performed. gone.
Specifically, a process cartridge incorporating an electrophotographic roller as a developing roller was attached to the color laser printer. Then, 10 halftone images (images in which horizontal lines with a width of 1 dot and an interval of 2 dots are drawn in the direction perpendicular to the rotation direction of the photoreceptor) are continuously output, and the obtained images are visually observed to find streaks. Image defects were judged according to the following two criteria.
<Evaluation of streak-like image defects 8-1>
Rank A: No streak-like image defects are observed from the first sheet.
Rank B: A streak-like image defect is observed only on the first sheet.
Rank C: Image defects such as streaks are observed on the second and subsequent sheets.
<Evaluation of streak-like image defects 8-2>
Rank A: No streak-like image defect is observed in the entire longitudinal direction of the electrophotographic roller.
Rank B: A streak-like image defect is observed in a part of the longitudinal direction of the electrophotographic roller.
Rank C: A streak-like image defect is observed in a wide range in the longitudinal direction of the electrophotographic roller and conspicuous.

(Evaluation 9: Evaluation of Edge Scraping, Toner Fusion, and Image Defects Derived from Toner Fusion)
The above-mentioned color laser printer and a process cartridge incorporating an electrophotographic roller as a developing roller were allowed to acclimate for 24 hours in an environment with a temperature of 23° C. and a humidity of 50% RH.
After that, an electrophotographic roller was mounted as a developing roller on the color laser printer, and an image drawing a horizontal line with a width of 2 dots and an interval of 50 dots was continuously printed on 10,000 sheets.
During the continuous output of 10,000 sheets, the developing roller was taken out every 1,000 sheets, and the developing roller was visually observed.
<Evaluation 9-1: Evaluation of edge scraping>
Rank A: Edge scraping is not observed even after outputting 10,000 sheets.
Rank B: Edge scraping is not observed after outputting 8,000 sheets, but is observed after outputting 9,000 sheets.
Rank C: Edge scraping is not observed after outputting 5,000 sheets, but is observed after outputting 8,000 sheets.
Rank D: Scraping of edges is observed after outputting 5,000 sheets.
<Evaluation 9-2: Evaluation of Toner Fusion>
Rank A: No fusion of toner is observed even after outputting 10,000 sheets.
Rank B: Fusion of toner is not recognized after outputting 8000 sheets, but is recognized after outputting 9000 sheets.
Rank C: Fusion of toner is not recognized after outputting 5000 sheets, but is recognized after outputting 8000 sheets.
Rank D: Fusion of toner is observed after outputting 5,000 sheets.
<Evaluation 9-3: Evaluation of Image Failure Derived from Fusion of Toner>
During the continuous output of 10,000 sheets, the images output every 10 sheets were checked. When there was an image defect such as toner being transferred to the paper at intervals of one rotation of the electrophotographic roller in a portion other than the horizontal line, the output was temporarily stopped and the electrophotographic roller was removed from the process cartridge. When the position where the image defect occurred and the location and size of the fused portion of the toner on the electrophotographic roller were the same, the number of output sheets at the time of temporary stop was taken as the number of image defects caused by toner fusion.

<Examples 2 to 7, 9 to 12, 14, 15, 18>
A mixture for forming an elastic layer was prepared in the same manner as in Example 1, except that the materials shown in Table 3 were used in the amounts shown in Table 3. An elastic layer was formed in the same manner as in Examples except that the elastic layer-forming mixture was used, and an electrophotographic roller according to each example was produced. The obtained electrophotographic roller was evaluated in the same manner as in Example 1.
Details of the material types in Table 3 are shown in Tables 1 and 2. The same applies to the following examples.

<Example 8>
A mixture for forming an elastic layer was prepared in the same manner as in Example 1, except that the materials shown in Table 3 were used in the amounts shown in Table 3. An elastic layer was formed in the same manner as in Example 1, except that the elastic layer-forming mixture was used and the injection of the elastic layer-forming mixture into the cylindrical mold was performed in 5 seconds. An electrophotographic roller according to this example was produced. The obtained electrophotographic roller was evaluated in the same manner as in Example 1.

<Examples 13, 16, 17>
A mixture for forming an elastic layer was prepared in the same manner as in Example 1, except that the materials shown in Table 3 were used in the amounts shown in Table 3. An elastic layer was formed in the same manner as in Example 1, except that the elastic layer-forming mixture was used and the injection of the elastic layer-forming mixture into the cylindrical tubular mold was performed in 3 seconds. An electrophotographic roller according to each example was produced. The obtained electrophotographic roller was evaluated in the same manner as in Example 1.

なお、上記Ａ５の、テトラヒドロフラン－ネオペンチルグリコール共重合体は、構造式：ＨＯ－（ＣＨ_２ＣＨ_２ＣＨ_２ＣＨ_２Ｏ）ｍ－（ＣＨ_２Ｃ（ＣＨ_３）_２ＣＨ_２Ｏ）ｎ－で表されるポリエーテルグリコールである。

The tetrahydrofuran-neopentyl glycol copolymer of A5 above has the structural formula: HO--(CH ₂ CH ₂ CH ₂ CH ₂ O)m--(CH ₂ C(CH ₃ ) ₂ CH ₂ O)n-. is a polyether glycol represented.

なお、上記Ｂ２に係るクラレポリオールＣ－２０９０（クラレ株式会社製ポリカーボネートポリオール；数平均分子量１９９３；水酸基価５６．３ｍｇＫＯＨ／ｇ；１，６－ヘキサンジオール由来の構造と３－メチル－１，５－ペンタンジオール由来の構造とを有するポリカーボネートポリオールである。

In addition, Kuraray Polyol C-2090 (polycarbonate polyol manufactured by Kuraray Co., Ltd.; number average molecular weight 1993; hydroxyl value 56.3 mgKOH / g; structure derived from 1,6-hexanediol and 3-methyl-1,5- It is a polycarbonate polyol having a structure derived from pentanediol.

<Comparative Example 1>
(Preparation of Elastic Layer-Forming Mixture)
Polypropylene glycol (trade name: PREMINOL S4013F, manufactured by AGC Corporation) 24.9 parts by mass and polypropylene glycol (trade name: Uniol D-4000, manufactured by NOF Corporation) 24.0 parts by mass, xylylene diisocyanate (XDI) ( Tokyo Chemical Industry Co., Ltd.) 3.1 parts by mass of a curing catalyst (trade name: RZETA, manufactured by Tosoh Corporation) 500 ppm was added and stirred for 4 hours in a closed mixer adjusted to 100 ° C. to form two isocyanate groups. A polyether having
41.5 parts by mass of polycarbonate diol (Duranol G3452, manufactured by Asahi Kasei Corporation) was mixed with this. After that, by stirring for another 2 hours in a closed mixer adjusted to 100° C., a urethane reactive emulsifier having two hydroxyl groups was synthesized, and a dispersion in which droplets containing the urethane reactive emulsifier were dispersed in polycarbonate diol was obtained. Obtained.
To this dispersion, 4.7 parts by mass of polyisocyanate (trade name: Millionate MR-200, manufactured by Tosoh Corporation) and 1.8 parts by mass of an ion conductive agent (trade name: CIL-542: manufactured by Nihon Carlit Co., Ltd.) were added. The mixture was stirred for 2 minutes at a revolution speed of 1600 rpm with a rotation-revolution vacuum defoaming mixer to obtain a mixture for forming an elastic layer. An electrophotographic roller according to this comparative example was obtained in the same manner as in Example 1, except that the elastic layer forming mixture thus obtained was used. The obtained electrophotographic roller was evaluated in the same manner as in Example 1.

Regarding the results of evaluation 1, the matrix and the domains were clearly phase-separated. It was also confirmed that the matrix contained a urethane elastomer composed of polyether, and the domain contained a urethane elastomer composed of polycarbonate. That is, the relationship between the domains and the matrix was reversed from that of the polyurethane elastomer according to Example 1.

<Comparative Example 2>
(Preparation of Elastic Layer-Forming Mixture)
20.1 parts by mass of polypropylene glycol (trade name: PREMINOL S4013F, manufactured by AGC Corporation) and 19.2 parts by mass of polypropylene glycol (trade name: Uniol D-4000, manufactured by NOF Corporation), polycarbonate diol (trade name: 500 ppm of a curing catalyst (trade name: RZETA, manufactured by Tosoh Corporation) was added to 50.3 parts by mass of Duranol G3452, manufactured by Asahi Kasei Corporation), and the mixture was stirred for 2 hours with a closed mixer adjusted to 100°C. To this, xylylene diisocyanate (XDI) (manufactured by Tokyo Chemical Industry Co., Ltd.) 3.3 parts by mass, polyisocyanate (trade name: Millionate MR-200, manufactured by Tosoh Corporation) 5.2 parts by mass, ion conductive agent (trade name : CIL-542, manufactured by Nihon Carlit Co., Ltd.) was added in an amount of 1.8 parts by mass. The resulting mixture was stirred for 2 minutes in a closed vacuum mixer to obtain an elastic layer-forming mixture.
An elastic layer was formed in the same manner as in Example 1 except that the elastic layer-forming mixture was used, and an electrophotographic roller according to this comparative example was produced. The obtained electrophotographic roller was evaluated in the same manner as in Example 1.

<Comparative Example 3>
(Preparation of Elastic Layer-Forming Mixture)
7.0 parts by mass of polypropylene glycol (trade name: Uniol D-2000, manufactured by NOF Corporation), 79.0 parts by mass of polycarbonate diol (Duranol T6002, manufactured by Asahi Kasei Corporation) and a curing catalyst (trade name: RZETA, Tosoh Co., Ltd.) 500 ppm was added, and the mixture was stirred for 2 hours with a closed mixer adjusted to 100°C.
To this, xylylene diisocyanate (XDI) (manufactured by Tokyo Chemical Industry Co., Ltd.) 4.3 parts by mass, polyisocyanate (trade name: Millionate MR-200, manufactured by Tosoh Corporation) 8.0 parts by mass, ion conductive agent (trade name 1.8 parts by mass of CIL-542: manufactured by Nihon Carlit Co., Ltd. was added. The resulting mixture was stirred for 2 minutes in a closed vacuum mixer to obtain an elastic layer-forming mixture.
An elastic layer was formed in the same manner as in Example 1 except that the elastic layer-forming mixture was used, and an electrophotographic roller according to this comparative example was produced. The obtained electrophotographic roller was evaluated in the same manner as in Example 1.

<Comparative Example 4>
(Preparation of Elastic Layer-Forming Mixture)
Polycarbonate diol (trade name: Kuraray Polyol C-2090, manufactured by Kuraray Co., Ltd.) 46.7 parts by mass and silicone particles (trade name: KMP-598, manufactured by Shin-Etsu Chemical Co., Ltd.) 44.8 parts by mass, which are flexible resin particles 500 ppm of a curing catalyst (trade name: RZETA, manufactured by Tosoh Corporation) was added to the mixture, and the mixture was stirred for 4 hours with a closed vacuum mixer adjusted to 100°C.
To this, xylylene diisocyanate (XDI) (manufactured by Tokyo Chemical Industry Co., Ltd.) 2.6 parts by mass, polyisocyanate (trade name: Millionate MR-200, manufactured by Tosoh Corporation) 84.2 parts by mass, ion conductive agent (trade name 1.8 parts by mass of CIL-542: manufactured by Nihon Carlit Co., Ltd. was added. The resulting mixture was stirred for 2 minutes with a revolution-type vacuum defoaming mixer at a revolution speed of 1600 rpm to obtain a mixture for forming an elastic layer.
An elastic layer was formed in the same manner as in Example 1 except that the elastic layer-forming mixture was used, and an electrophotographic roller according to this comparative example was produced. The obtained electrophotographic roller was evaluated in the same manner as in Example 1. In the evaluation of the electrophotographic roller according to this comparative example, the silicone particles were regarded as domains.
Evaluation results of Examples 1 to 18 and Comparative Examples 1 to 4 are shown in Tables 4-1 to 4-4 and Table 5.

In the electrophotographic rollers according to Examples 1 to 18, the elastic layer had a low microrubber hardness, and a plurality of domains were dispersed in the matrix containing the urethane elastomer. In addition, the parameter B indicating the viscoelasticity term of the matrix is larger than the parameter A indicating the viscoelasticity term of the domain, and the distortion after unloading in the indentation test using the nanoindenter is small, so the evaluation of the streak-like image defect Good results were obtained for In addition, although toner fusion was observed in some electrophotographic rollers, no image defects due to toner fusion occurred until 10,000 sheets were output.
On the other hand, in the electrophotographic roller according to Comparative Example 1, the parameter A indicating the domain viscoelasticity term was larger than the parameter B indicating the matrix viscoelasticity term. As a result, the micro-rubber hardness was excessively lowered and the strain after unloading was increased, and the evaluation of streak-like image defects was not good.
In the electrophotographic roller according to Comparative Example 2, a matrix domain structure was formed by mechanical phase separation without going through the polyether and the urethane reactive emulsifier. Therefore, the phase separation was unclear. In addition, since the circularity of the domains was also reduced, the microrubber hardness was excessively lowered and the distortion after unloading was increased, and the evaluation of the streak-like image defect was not good.
The electrophotographic roller according to Comparative Example 3 was also phase-separated mechanically without passing through the urethane reactive emulsifier in the same manner as in Comparative Example 2. Therefore, the phase separation was unclear. In addition, since the degree of circularity of the domain was also reduced, the strain after unloading was increased, and the evaluation of streak-like image defects was not good. Further, even after that, the distortion did not recover easily, and the toner adhered to the distorted portion and further fused, resulting in image defects due to toner fusion on 8,410 sheets. In the electrophotographic roller according to Comparative Example 4, soft particles were used as the domains, but in order to maintain the shape of the particles, the parameter A indicating the viscoelastic term was much larger than that of the domains according to the present disclosure. Moreover, the parameter B, which indicates the viscoelasticity term of the matrix, must also be increased. Further, since the micro-rubber hardness was too high, the fusion of the toner further progressed, and image defects resulting from the fusion of the toner occurred on 5,550 sheets.

The present disclosure is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Accordingly, the following claims are appended to publicize the scope of the present disclosure.

1A, 1B Electrophotographic member 2: Mandrel 3: Elastic layer 31: Matrix 32: Domain

Claims (10)

An electrophotographic member comprising a mandrel and an elastic layer provided on its outer periphery,
the elastic layer comprises a urethane elastomer having a matrix and a plurality of domains dispersed in the matrix;
The relationship between parameter A indicating the viscoelastic term of the domain measured in a viscoelastic image of the cross section in the thickness direction of the elastic layer with a scanning probe microscope and parameter B indicating the viscoelastic term of the matrix is A <B,
The elastic layer has a micro-rubber hardness of 20 or more and 50 or less at a temperature of 23°C, and
In an indentation test using a nanoindenter at 23°C of the elastic layer, a Vickers indenter was indented at a load rate of 10 mN/30 seconds, the load was maintained at 10 mN for 60 seconds, and then unloaded. An electrophotographic member characterized by having a thickness of 1 μm or less. 2. The electrophotographic member according to claim 1, wherein the matrix has an elastic modulus of 2 MPa or more and 8 MPa or less. When the length of the elastic layer in the longitudinal direction is L, the thickness direction of the elastic layer at three locations, the center in the longitudinal direction of the elastic layer and L/4 from both ends toward the center of the elastic layer. For each of the cross sections, when an observation area of 50 μm square is arbitrarily placed in a thickness area from the outer surface of the elastic layer to a depth of 100 μm, all three of the observation areas meet the following requirements (1) and requirements (2 ), the electrophotographic member according to claim 1 or 2, wherein:
Requirement (1) The ratio of the total cross-sectional area of the domain is 15% or more and 45% or less of the observation area.
Requirement (2) The ratio of the number of domains having a cross-sectional area of 0.1% or more and 13.0% or less to the observation area is 70% or more. 4. The electrophotography according to any one of claims 1 to 3, wherein the ratio of the number of domains having a degree of circularity of 0.60 to 0.95 is 70% or more in all three observation regions. material. The matrix contains a urethane elastomer having a polycarbonate structural unit represented by general formula (1) as a repeating structural unit, and
5. The electrophotographic member according to claim 1, wherein the domain contains a polyether structural unit represented by general formula (2) as a repeating structural unit.

(R ₁ represents an alkylene group having 3 to 9 carbon atoms.)

(R ₂ represents an alkylene group having 3 to 5 carbon atoms.) 6. The electrophotographic member according to claim 5, wherein R ₁ in the repeating structural unit represented by formula (1) is an alkylene group having a branched structure with 3 to 9 carbon atoms. 7. The electrophotographic member according to claim 5, wherein R ₂ in the repeating structural unit represented by formula (2) is an alkylene group having a branched structure with 3 to 5 carbon atoms. A process cartridge detachably attached to an image forming apparatus, comprising the electrophotographic member according to any one of claims 1 to 7. An electrophotographic image forming apparatus comprising the electrophotographic member according to any one of claims 1 to 7. A method for producing an electrophotographic member according to any one of claims 1 to 7,
(i) reacting a first polyether having at least two isocyanate groups with a first polycarbonate polyol having at least two hydroxyl groups to obtain a urethane reactive emulsifier having at least two hydroxyl groups;
(ii) obtaining a dispersion of droplets comprising at least a portion of said urethane reactive emulsifier dispersed in a second polycarbonate polyol;
(iii) mixing the dispersion and a polyisocyanate having at least two isocyanate groups to obtain a mixture for forming an elastic layer; and (iv) applying the mixture for forming an elastic layer on the surface of the mandrel. a step of reacting the urethane reactive emulsifier in the above, the second polycarbonate polyol, and the polyisocyanate to obtain the elastic layer.

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