阅读说明：本技术 电子照相用构件、处理盒和电子照相图像形成设备 (Electrophotographic member, process cartridge, and electrophotographic image forming apparatus ) 是由 小川祥宽 杉山辽 长冈一聪 松永贤太 石井亨 有村秀哉 宇津野文彦 上杉知也 盛合涉 于 2020-03-26 设计创作，主要内容包括：本发明涉及电子照相用构件、处理盒和电子照相图像形成设备。所述电子照相用构件包括：导电性基体；和具有单层结构的表面层,其中所述表面层具有含有交联聚氨酯树脂作为粘结剂的基质,和在沿厚度方向从所述表面层的外表面至距离所述表面层的外表面0.1μm的深度的第一区域中所述基质的弹性模量定义为E1,且在沿厚度方向从距离所述表面层的外表面1.0μm的深度至距离所述表面层的外表面1.1μm的第二区域中所述基质的弹性模量定义为E2时,E1和E2分别满足下式(1)和(2)：E1≥200MPa (1)；和10MPa≤E2≤100MPa (2)。(The invention relates to an electrophotographic member, a process cartridge, and an electrophotographic image forming apparatus. The electrophotographic member includes: a conductive substrate; and a surface layer having a single-layer structure, wherein the surface layer has a matrix containing a crosslinked polyurethane resin as a binder, and an elastic modulus of the matrix is defined as E1 in a first region from an outer surface of the surface layer to a depth of 0.1 μm from the outer surface of the surface layer in a thickness direction, and E1 and E2 satisfy the following formulas (1) and (2), respectively, when an elastic modulus of the matrix is defined as E2 in a second region from a depth of 1.0 μm from the outer surface of the surface layer to 1.1 μm from the outer surface of the surface layer in the thickness direction: e1 is more than or equal to 200MPa (1); and E2 is more than or equal to 10MPa and less than or equal to 100MPa (2).)

1. An electrophotographic member, comprising:

a conductive substrate; and

a surface layer having a single-layer structure formed on the substrate,

characterized in that the surface layer has a matrix containing a crosslinked polyurethane resin as a binder, and

the modulus of elasticity of the matrix is defined as E1 in a first region from the outer surface of the surface layer to a depth of 0.1 μm from the outer surface of the surface layer in the thickness direction, and the modulus of elasticity of the matrix is defined as E2, E1 and E2 satisfy the following formulae (1) and (2), respectively, when measured from a depth of 1.0 μm from the outer surface of the surface layer to a second region of 1.1 μm from the outer surface of the surface layer in the thickness direction, E1 and E2 are cross-sectional in the thickness direction of the surface layer:

e1 is more than or equal to 200MPa (1); and

10MPa≤E2≤100MPa (2)。

2. the member for electrophotography according to claim 1, wherein an elastic modulus of the matrix in a third region from a depth of 0.5 μm from the outer surface of the surface layer to 0.6 μm from the outer surface of the surface layer is defined as E3, E3 being measured in a cross section of the surface layer in the thickness direction, E1 and E3 satisfy a relationship represented by the following formula (3):

(E1-E3)/E3>1 (3)。

3. the electrophotographic member according to claim 1 or 2, wherein the surface layer contains a crosslinked acrylic resin, the crosslinked acrylic resin and the crosslinked polyurethane resin together constituting an interpenetrating polymer network structure.

4. The electrophotographic member according to claim 3, wherein the monomer forming the crosslinked acrylic resin is a polyfunctional monomer having an acryloyl group or a methacryloyl group as a functional group, and the total number of acryloyl groups or methacryloyl groups contained in one molecule is 2 or 3.

5. The member for electrophotography according to claim 3,

wherein when the peak top temperature from the thermal chromatogram of the crosslinked acrylic resin is defined as A1 ℃, A1 is measured from a first sample sampled from the first region, and

the peak top temperature from the thermal chromatogram of the crosslinked acrylic resin was defined as A2 deg.C, A2 when measured from a second sample obtained by decomposing the crosslinked polyurethane resin contained in the first sample,

a1 and a2 satisfy the relationship represented by the following formula (4):

A1>A2 (4)。

6. the member for electrophotography according to claim 1 or 2,

wherein when the peak top temperature from the thermal chromatogram of the crosslinked polyurethane resin is defined as T1 ℃, T1 is measured from a first sample sampled from the first region, and

the peak top temperature from the thermal chromatogram of the crosslinked polyurethane resin is defined as T2 deg.C, T2 when measured from a third sample sampled from the second region,

t1 and T2 satisfy the relationship represented by the following formula (5):

T1>T2 (5)。

7. the electrophotographic member according to claim 6, wherein T1 and T2 satisfy a relationship represented by the following formula (6):

(T1-T2)>1.0 (6)。

8. the member for electrophotography according to claim 6, wherein when a peak top temperature from a thermal chromatogram of the crosslinked polyurethane resin is defined as T3 ℃, T3 is measured from a section of a fourth sample in the thickness direction of the surface layer sampled from a depth of 0.5 μm from the outer surface of the surface layer to a third region of 0.6 μm from the outer surface of the surface layer, T1, T2, and T3 satisfy relationships represented by the following formulae (7) and (8):

t1> T3 (7); and

|T1-T3|>|T3-T2| (8)。

9. the electrophotographic member according to claim 1 or 2, wherein the surface layer further contains one or more of a modified silicone compound and a modified fluorine compound.

10. An electrophotographic process cartridge detachably mountable to a main body of an electrophotographic apparatus, characterized in that the electrophotographic process cartridge comprises the member for electrophotography according to any one of claims 1 to 9.

11. An electrophotographic process cartridge according to claim 10, wherein said electrophotographic member is included as a developing member.

12. An electrophotographic image forming apparatus, comprising: an image carrier bearing an electrostatic latent image; a charging device for charging the image carrier at a time; an exposure device that forms an electrostatic latent image on the image carrier that is charged once; a developing member that develops the electrostatic latent image with a toner and forms a toner image; and a transfer device that transfers the toner image onto a transfer material, characterized in that the developing member is the electrophotographic member according to any one of claims 1 to 9.

Technical Field

The present disclosure relates to an electrophotographic member incorporated in an apparatus employing an electrophotographic system. In addition, the present disclosure relates to a process cartridge and an electrophotographic image forming apparatus including the electrophotographic member.

Background

In an electrophotographic image forming apparatus (also referred to as an "electrophotographic apparatus") according to an aspect, an image carrier is charged by a charging unit, and an electrostatic latent image is formed by laser light. Next, the toner in the developing container is applied to the developing member by the toner supply roller and the toner regulating member, thereby developing the electrostatic latent image with the toner by bringing the image carrier into contact with or close to the developing member. Subsequently, the toner on the image carrier is transferred onto the recording paper by the transfer unit and fixed by heat and pressure, and the toner remaining on the image carrier is removed by the cleaning blade.

Such electrophotographic apparatuses are required to have higher image quality and durability, and faster laser printing speed than before. Therefore, the electrophotographic member is also required to have higher performance.

For example, in the case where the durable life of an electrophotographic apparatus is greatly extended, the surface of an electrophotographic member according to the related art is repeatedly rubbed to scratch and thus scratches may be generated thereon. In addition, significant film formation can occur due to adhesion or deposition of the developer components. It may be difficult to form a high-quality electrophotographic image by using such an electrophotographic member. In order to stably and continuously output high-quality electrophotographic images for a long period of time, there is a demand for electrophotographic members in which the generation of scratches or the generation of film formation due to surface layer scratches is suppressed at a high level, that is, electrophotographic members having excellent durability.

Japanese patent application laid-open No. 2014-197064 discloses a modified rubber elastomer including a rubber elastomer having rubber elasticity and a surface treatment layer composed of a cured product of a photocurable composition impregnated from the surface thereof in the rubber elastomer, and an electrophotographic member using the same. The photocurable composition includes a (meth) acrylic monomer; a photopolymerizable polymer having a silicon-containing group and/or a fluorine-containing group and a (meth) acryloyl group in a molecule; and a photopolymerization initiator. Further, it is disclosed that according to the electrophotographic member, both releasability and low friction property of the toner are achieved.

Disclosure of Invention

An aspect of the present disclosure is to provide an electrophotographic member capable of realizing formation of a high-quality electrophotographic image for a long period of time.

Another aspect of the present disclosure is directed to providing a process cartridge that facilitates stable formation of high-quality electrophotographic images.

Still another aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image.

According to an aspect of the present disclosure, there is provided an electrophotographic member including: a conductive substrate; and a surface layer having a single-layer structure on the substrate, wherein the surface layer has a matrix containing a crosslinked polyurethane resin as a binder, and an elastic modulus of the matrix is defined as E1 in a first region from an outer surface of the surface layer to a depth of 0.1 μm from the outer surface of the surface layer in a thickness direction, as E2 in a second region from a depth of 1.0 μm from the outer surface of the surface layer to a depth of 1.1 μm from the outer surface of the surface layer in the thickness direction, as measured on a cross section of the surface layer in the thickness direction, as E1 and E2, E1 and E2 satisfy the following formulae (1) and (2), respectively:

e1 is more than or equal to 200MPa (1); and

10MPa≤E2≤100MPa (2)。

according to another aspect of the present disclosure, there is provided a process cartridge detachably mountable to a main body of an electrophotographic image forming apparatus, including the member for electrophotography.

According to still another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including: an image carrier bearing an electrostatic latent image; a charging device for charging the image carrier at a time; an exposure device that forms an electrostatic latent image on the image carrier that is charged once; a developing member that develops the electrostatic latent image with a toner and forms a toner image; a transfer device for transferring the toner image onto a transfer material, wherein the developing member is the above-mentioned electrophotographic member.

Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Drawings

Fig. 1A and 1B are schematic views illustrating a member for electrophotography according to an embodiment of the present disclosure.

Fig. 2 is a schematic view of an electrophotographic image forming apparatus according to an embodiment of the present disclosure.

Fig. 3 is a schematic view of a process cartridge according to an embodiment of the present disclosure.

Fig. 4 is a sectional view of a member for electrophotography according to an embodiment of the present disclosure.

Detailed Description

As disclosed in japanese patent application laid-open No. 2014-197064, in the case where an electrophotographic member formed of a rubber composition treated with a treatment liquid containing a polymer is provided for forming a plurality of electrophotographic images in a high-temperature environment, film formation or scratches may occur on the surface of the electrophotographic member. It is considered that the reason why filming easily occurs is that since an acrylic polymer having high hardness is present at a depth of about several micrometers near the surface of the electrophotographic member, a large load is applied to the toner, and the deteriorated toner is thereby fixed to the surface of the electrophotographic member. Further, it is considered that the scratch is caused because the acrylic polymer present on the surface of the electrophotographic member has low toughness, and thus cracks are easily generated by friction with other members.

Therefore, as a result of repeated studies, attention is paid to the elastic modulus of the surface layer of the electrophotographic member in the depth direction. That is, it was found that by optimizing the elastic modulus, even if a plurality of sheets are printed in a high-temperature environment at the same time in long-term use, the generation of scratches due to surface scratches of the electrophotographic member can be suppressed without serious film formation.

The electrophotographic member according to an embodiment of the present disclosure includes a conductive substrate; and a surface layer having a single-layer structure on the substrate. The surface layer has a matrix containing a crosslinked polyurethane resin as a binder. The modulus of elasticity of the matrix in a first region from the outer surface of the surface layer to a depth of 0.1 μm from the outer surface of the surface layer in the thickness direction is defined as E1, and the modulus of elasticity of the matrix in a second region from a depth of 1.0 μm from the outer surface of the surface layer to 1.1 μm from the outer surface of the surface layer in the thickness direction is defined as E2, and E1 and E2 satisfy the following formulas (1) and (2), respectively, when measured on a cross section of the surface layer in the thickness direction:

e1 is more than or equal to 200MPa (1); and

10MPa≤E2≤100MPa (2)。

the reasons why scratches of the electrophotographic member due to surface layer scratches and filming due to toner deterioration in a high-temperature environment can be suppressed are observed as follows.

The urethane bond is crosslinked by reacting the polyol hydroxyl group and the isocyanate compound with each other, thereby obtaining a crosslinked polyurethane resin. Here, crosslinking means that the resulting polyurethane resin has a three-dimensional network structure rather than a linear structure because either one or both of the polyol or isocyanate compound has three or more reactive functional groups.

In addition, in the present embodiment, the elastic modulus E1 of the first region in the vicinity of the outer surface is set high, and the elastic modulus E2 of the second region having a predetermined depth is set low.

Therefore, in order to increase the elastic modulus of the surface side of the crosslinked polyurethane resin constituting the matrix of the surface layer, for example, an interpenetrating polymer network structure is formed.

First, the interpenetrating polymer network structure will be described. The interpenetrating polymer network structure (hereinafter, referred to as an IPN structure) is a structure in which two or more polymer networks are not bonded by covalent bonds but are interlaced and entangled with each other. In addition, the structure is not disassembled unless the polymer chains forming the network are cut.

Various methods can be used to form the IPN structure. The method of forming the IPN structure may include a sequential network formation method in which the first component polymeric network is first formed and then the second component polymeric network is formed after swelling the first component polymeric network with the second component monomer and the polymerization initiator. Alternatively, an example of the formation method of the IPN structure may include a simultaneous network formation method in which a first component monomer and a second component monomer having different reaction mechanisms are mixed with respective polymerization initiators to simultaneously form a network.

In the present embodiment, the IPN structure is preferably formed by using a crosslinked polymer, particularly a crosslinked acrylic resin having a higher elastic modulus than the crosslinked urethane resin. The IPN structure is formed by: the crosslinked urethane resin, i.e., the first component, is impregnated with an acrylic monomer and a polymerization initiator from the outer surface, and then the crosslinked acrylic resin is formed as the second component polymer. In this case, the acrylic monomer intrudes into the three-dimensional network structure of the crosslinked urethane resin and polymerizes, thereby forming a network structure of the crosslinked acrylic resin.

In the present embodiment, an IPN structure composed of a crosslinked urethane resin and a crosslinked acrylic resin is formed, the IPN structure having a thickness of about 1 μm in the depth direction from the surface of the crosslinked urethane resin. In a high-temperature environment, strength is increased by IPN structure introduction, and a conflict occurs between scratches due to surface layer scratching and filming due to toner deterioration. That is, in the case where the IPN structure is formed in a large thickness in the depth direction from the outer surface, although scratches due to surface layer scratches can be suppressed, the load on the toner increases, and film formation is therefore deteriorated.

On the other hand, in the case of forming an IPN structure with a small thickness in the depth direction from the outer surface, the load on the toner can be reduced and film formation can be suppressed, but the amount of the crosslinked acrylic resin should be reduced, and thus the strength of the outer surface is not sufficiently ensured, thereby deteriorating scratches due to surface layer scratches. The method of increasing the strength may include a method of significantly increasing the crosslink density of the rubber constituting the surface of the electrophotographic member, but in the case of this method, the hardness increases depending on the increase in the strength. Therefore, the load on the toner increases, and the film formation is deteriorated. In addition, when the strength is increased by this method, the bendability is lowered and embrittlement occurs, and on the contrary, scratches due to surface layer scratching are deteriorated.

In the configuration of the present embodiment, the strength by the IPN structure composed of the crosslinked acrylic resin is locally increased in the vicinity of the outermost surface of the surface layer, thereby exhibiting strength and flexibility. Therefore, it is not necessary to increase the crosslinking density unnecessarily, and the bendability and flexibility are not lost. Therefore, in the configuration of the present embodiment, the load on the toner is suppressed and the film formation is not deteriorated regardless of the high strength. That is, generation of scratches and occurrence of film formation due to surface layer scratching can be greatly suppressed at a high level.

In addition, in order to improve the charging stability, durable developability, fluidity, and durability of the toner, in general, the toner is preferably obtained by adding a metal oxide such as alumina fine particles, titania fine particles, or silica fine particles as an additive to toner particles, however, the Young's modulus of the additive is usually about 50GPa (50 × 10)⁹Pa) to 500GPa (500 × 10⁹Pa) and when the additive is repeatedly rubbed with the outer surface of the rubber or resin constituting the surface of the electrophotographic memberThe scratch due to the outer surface scratch is deteriorated.

On the other hand, in the present embodiment, the elastic modulus E1 of the first region is 200MPa (200 × 10)⁶Pa) or more, generation of scratches and occurrence of film formation due to surface layer scratching can be greatly suppressed at a high level.

In addition, the main component of the toner is usually a resin material such as an ester-based resin or a styrene acrylic resin, and the storage elastic modulus at 30 ℃ in viscoelasticity measurement of the toner is 10MPa (10 × 10)⁶Pa) or more and 10GPa (10 × 10)⁹Pa) or less. However, when the toner repeatedly rubs against the outer surface of the rubber or resin constituting the surface of the electrophotographic member, the toner is broken or deformed, and filming is thus deteriorated.

On the other hand, in the configuration of the present embodiment, the strength is high in the vicinity of the outer surface of the surface layer, the flexibility inside the surface layer is sufficiently maintained, and the generation of scratches and the occurrence of filming due to scratching of the surface layer can be greatly suppressed at a high level.in the case where the elastic modulus from the depth of 1.0 μm from the outer surface of the surface layer to the second region of 1.1 μm from the outer surface of the surface layer is E2, E2 is 10MPa (10 × 10)⁶Pa) or more and 100MPa (100 × 10)⁶Pa) or less, preferably 20MPa or more and 50MPa or less.

It should be noted that the upper limit of the elastic modulus E1 of the first region is not particularly limited, but the relationship between the elastic modulus E1 of the first region in the thickness direction of the later-described surface layer and the elastic modulus E2 of the second region or the elastic modulus E3 of the third region is set within an appropriate range, in general, the elastic modulus E1 of the first region is preferably 4,500MPa (4,500 × 10)⁶Pa) or less.

In addition, the surface layer may contain a surfactant such as a modified silicone compound or a modified fluorine compound in addition to the crosslinked polyurethane resin. The surfactant may have both a low-polarity group such as a silicon-containing group or a fluorine-containing group and a high-polarity group at the modified site.

Since the difference in polarity between the urethane group or other highly polar group of the crosslinked polyurethane resin and the low polar group such as a silicon-containing group or a fluorine-containing group in the molecule of the surfactant is large, the surfactant migrates and stays near the outer surface of the surface layer. In addition, in the case where the acrylic monomer and the polymerization initiator swell the surfactant-containing crosslinked polyurethane resin from the outer surface, when the acrylic monomer having a small polarity difference from the highly polar group in the surfactant molecule is used, the acrylic monomer stays in the vicinity of the surfactant. That is, the acrylic monomer stays near the outer surface and is cured, so that the IPN structure may be locally formed near the outer surface of the surface layer.

Examples of the modified silicone compound may include commercially available polyether-modified silicone oils such as "TSF-4445" (trade name, manufactured by Momentive Performance Materials Japan LLC).

In addition, examples of the surfactant having a fluorine-containing group may include commercially available oligomers containing a fluorine-containing group, such as "MEGAFUC F430" (trade name, manufactured by DIC Corporation).

Hereinafter, an electrophotographic member having a roller shape (hereinafter, also referred to as "electrophotographic roller") preferably obtainable as a developing member according to an embodiment of the present disclosure will be described, but the shape of the electrophotographic member is not limited thereto.

Fig. 1A is a circumferential sectional view of an electrophotographic roller, which includes a conductive mandrel 2 as a conductive substrate, and a surface layer 1 formed on the circumferential surface of the substrate. Fig. 1B is a circumferential sectional view of a roller-shaped electrophotographic member, which includes a mandrel 2 as a conductive substrate, and an intermediate layer 3 between a surface layer 1 and the mandrel 2. The intermediate layer 3 is not limited to a single layer, and may be a plurality of layers. For example, in the non-magnetic one-component contact development process, it is preferable to use a developing member including a surface layer 1, the surface layer 1 being formed on a conductive substrate (mandrel 2) on which an intermediate layer 3 is laminated.

[ conductive substrate ]

As the conductive substrate, a cylindrical or hollow cylindrical conductive mandrel, or a cylindrical or hollow cylindrical conductive mandrel on which an intermediate layer having a single layer or multiple layers is further provided may be used. The mandrel has a cylindrical or hollow cylindrical shape, and is formed of the following conductive material. The mandrel may be made of metals or alloys such as aluminum, copper alloys, and stainless steel; chromium or nickel plated iron; or conductive synthetic resin. A known adhesive may also be applied to the surface of the mandrel 2 in order to improve the adhesion of the intermediate layer 3 or the surface layer 1 formed on the periphery thereof.

As described above, in the non-magnetic one-component contact developing process, it is preferable to use a developing member in which the intermediate layer 3 is laminated between the core shaft 2 and the surface layer 1. The intermediate layer applies hardness and elasticity to a developing member pressed against the image carrier with an appropriate nip width and nip pressure, so that an appropriate amount of toner can be supplied to the electrostatic latent image formed on the surface of the image carrier.

The intermediate layer is preferably made of a molded article formed of a general rubber material. Examples of the rubber material may include the following materials: ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), Chloroprene Rubber (CR), Natural Rubber (NR), Isoprene Rubber (IR), styrene-butadiene rubber (SBR), fluororubber, silicone rubber, epichlorohydrin rubber, hydride of NBR, and urethane rubber. These rubber materials may be used alone or in combination of two or more thereof. Among them, in particular, silicone rubber is preferable because it is less likely to generate compression set even in the case where the developing member is in long-term contact with other members (e.g., toner regulating member). Specific examples of the silicone rubber may include a cured product formed from an addition curing type silicone rubber.

As the intermediate layer, an intermediate layer formed of a rubber material containing a conductivity-imparting agent such as an electron-conductive substance or an ion-conductive substance can be used. The volume resistivity of the intermediate layer is adjusted to preferably 10³Omega cm or more and 10¹¹Not more than Ω cm, more preferably 10⁴Omega cm or more and 10¹⁰Omega cm or less.

Examples of the electron conductive substance may include the following substances: carbon black such as conductive carbon, carbon for rubber, or carbon for color (ink), for example, conductive carbon black such as Ketjenblack EC or acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT or MT; color (ink) carbon subjected to oxidation treatment; and metals such as copper, silver or germanium, and metal oxides thereof. Among them, conductive carbon [ conductive carbon, carbon for rubber, or carbon for color (ink) ] is preferable because conductivity is easily controlled in a small amount thereof.

Examples of the ion conductive substance may include the following substances: inorganic ion conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, or lithium chloride; and organic ion conductive substances such as modified aliphatic dimethylammonium ethylsulfate or stearyl ammonium acetate.

These conductivity imparting agents are used in an amount necessary to adjust the intermediate layer to have an appropriate volume resistivity. Usually, the conductivity-imparting agent is used in a range of 0.5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin.

In addition, the intermediate layer may further contain various additives such as plasticizers, fillers, extenders, vulcanizing agents, vulcanization aids, crosslinking aids, curing inhibitors, antioxidants, aging inhibitors, and processing aids, as necessary. Examples of the filler may include silica, quartz powder, and calcium carbonate. These optional components are contained within a range that does not impair the function of the intermediate layer.

The intermediate layer has elasticity required for the developing member. The elasticity of the intermediate layer preferably has an Asker C hardness of 20 degrees or more and 100 degrees or less. The thickness of the intermediate layer is preferably 0.3mm or more and 6.0mm or less.

The respective materials of the intermediate layer may be mixed using a dynamic mixing device such as a uniaxial continuous kneader, biaxial continuous kneader, two rolls, kneader mixer, or triple mixer, or a static mixing device such as a static mixer.

The method of forming the intermediate layer on the mandrel is not particularly limited, and examples thereof may include a die forming method, an extrusion forming method, an injection forming method, and a coating forming method. Examples of the mold forming method may include the following methods: a work for holding a mandrel in a cylindrical mold is fixed to both ends of the cylindrical mold, an injection port is formed in the work, the mandrel is then arranged in the mold, a material for an intermediate layer is injected into the mold through the injection port, and then the mold is heated at a temperature at which the material is cured to thereby demold the mold. The mold is then demolded by entering the mold through an injection port and then heating the mold at a temperature that cures the material. Examples of the extrusion molding method may include the following methods: the mandrel and the material for the intermediate layer were co-extruded with a crosshead extruder and the material was cured to form the intermediate layer around the mandrel.

The surface of the intermediate layer may be modified by surface grinding or surface modification methods such as corona treatment, flame treatment, or excimer treatment to enhance adhesion to the surface layer.

[ surface layer ]

The surface layer is a single layer provided on the outermost surface of the electrophotographic member, and in the case of a roller-shaped member, the surface layer is provided on the outermost peripheral surface. The surface layer may be formed directly on the mandrel, but the surface layer may be formed on the outer peripheral surface of the base including the intermediate layer formed on the mandrel. The surface layer contains a binder resin. In addition, in the case of forming an IPN structure in which a crosslinked urethane resin is contained as a binder resin, an IPN structure in which a crosslinked acrylic resin and a crosslinked urethane resin are interpenetrated is preferable.

In addition, resin particles may be added to the surface layer so as to form convex portions on the surface of the electrophotographic member. In the case where the surface roughness is applied to the surface layer, fine particles that impart roughness to the surface layer may be contained. Specifically, fine particles formed of a polyurethane resin, a polyester resin, a polyether resin, a polyamide resin, an acrylic resin, or a polycarbonate resin may be used. These fine particles are preferably crosslinked resin particles. In the case where the IPN structure is formed on the outer surface of the surface layer, the IPN structure may also be formed inside the crosslinked resin particles. The volume average particle diameter of the fine particles is preferably 1.0 μm or more and 30 μm or less, and the surface roughness (ten-point average roughness) Rzjis formed by the fine particles is preferably 0.1 μm or more and 20 μm or less. It should be noted that Rzjis is a value measured based on JIS B0601 (1994).

[ method of Forming surface layer ]

Hereinafter, in the embodiment of the surface layer in which the IPN structure is composed of the crosslinked acrylic resin, the formation method of the surface layer will be described.

The surface layer of the present embodiment may be formed by the following steps:

forming a resin layer containing a crosslinked urethane resin as a binder resin on a conductive substrate;

impregnating a liquid acrylic monomer on an outer surface of the resin layer; and

curing the impregnated acrylic monomer.

The formation of the resin layer containing the crosslinked polyurethane resin is not particularly limited, but a coating method of a liquid coating material is preferable. For example, the resin layer may be formed by: the respective materials for the resin layer are dispersed and mixed in a solvent to prepare a coating material, the coating material is applied onto the conductive substrate, and the applied coating material is solidified or cured by heating. As the solvent, a polar solvent is preferable from the viewpoint of compatibility with a polyol or an isocyanate compound which is a raw material of the crosslinked polyurethane resin.

Examples of the polar solvent may include alcohols such as methanol, ethanol and n-propanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as methyl acetate and ethyl acetate. Among them, one solvent or a mixture of two or more solvents having favorable compatibility with other materials may be used.

The solid content in the preparation of the coating material can be freely adjusted by the amount of the solvent to be mixed, but is preferably 20 mass% or more and 40 mass% or less from the viewpoint of uniformly dispersing an electronic conductive substance such as carbon black described later. In the dispersing and mixing, a known dispersing apparatus using beads such as a sand MILL, a paint shaker, DYNO-MILL or a bead MILL may be used. In addition, dip coating, ring coating, spray coating or roll coating may be used as the coating method.

As the resin layer, a resin layer containing a crosslinked urethane resin containing a conductivity-imparting agent such as an electron-conductive substance or an ion-conductive substance can be used. The volume resistivity of the surface layer is adjusted to preferably 10³Omega cm or more and 10¹¹Not more than Ω cm, more preferably 10⁴Omega cm or more and 10¹⁰Omega cm or less.

As the electron conductive substance, a conductive filler described later can be used, but conductive carbon is preferable because the conductivity can be easily controlled by using a small amount thereof.

Examples of the ion conductive substance may include the following substances: inorganic ion conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, or lithium chloride; organic ion conductive substances such as modified aliphatic dimethyl ammonium ethyl sulfate or stearyl ammonium acetate.

These conductivity imparting agents are used in an amount necessary to adjust the surface layer to have an appropriate volume resistivity. Usually, the conductivity-imparting agent is used in a range of 0.5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin.

Next, the resin layer formed as described above is impregnated with a liquid acrylic monomer. The resin layer may be impregnated with a liquid acrylic monomer used as an impregnation solution, which is used as it is or appropriately diluted with various solvents. By appropriately diluting the liquid acrylic monomer with various solvents, the surface layer has a further uniform surface composition. As the solvent, any solvent may be freely selected as long as it is a solvent satisfying both affinity with the resin layer and solubility of the acrylic monomer.

Examples of the solvent may include alcohols such as methanol, ethanol and n-propanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as methyl acetate and ethyl acetate. In addition, a suitable polymerization initiator may be mixed with the impregnation solution. The polymerization initiator will be described in detail. The dipping method of the dipping solution is not particularly limited, but dip coating, ring coating, spray coating, or roll coating may be used.

As such, after the impregnation treatment by the impregnation solution, the surface layer may be formed by polymerizing and curing the acrylic monomer. The polymerization and curing method is not particularly limited, but known methods can be used. Specifically, examples of the polymerization and curing method may include a thermal curing method or an ultraviolet irradiation method.

Through such a procedure, the crosslinked acrylic resin is introduced into the network structure of the crosslinked polyurethane resin of the resin layer while being entangled with each other, thereby forming an IPN structure. In the present embodiment, the IPN structure is preferably composed of a crosslinked polymer, particularly a crosslinked acrylic resin having a higher elastic modulus than the crosslinked urethane resin.

The IPN structure is formed by: the crosslinked urethane resin, i.e., the first component, is impregnated with an acrylic monomer and a polymerization initiator from the outer surface, and then the crosslinked acrylic resin is formed as the second component polymer. In this case, the acrylic monomer intrudes into the three-dimensional network structure of the crosslinked urethane resin and polymerizes, thereby forming a network structure of the crosslinked acrylic resin. In order to satisfy the requirements of formulae (1) and (2), the thickness of the surface layer thus obtained is 1.1 μm or more, preferably 1.4 μm or more, more preferably 2.0 μm or more, from the viewpoint of film strength. The upper limit of the thickness of the surface layer is not particularly limited, but when the surface of the single layer is formed on the substrate on which the intermediate layer is formed, the upper limit of the thickness of the surface layer is 200.0 μm or less, preferably 160.0 μm or less, and more preferably 150.0 μm or less from the viewpoint of flexibility. Note that the thickness of the surface layer here refers to the film thickness of a portion excluding the convex portion formed by addition of coarse particles or the like.

[ Cross-Linked polyurethane resin ]

The surface layer has a matrix containing a crosslinked polyurethane resin as a binder. The crosslinked polyurethane resin is suitable as a binder because it has excellent flexibility and strength.

The polyurethane resin can be obtained from a polyol and an isocyanate, or a chain extender if necessary.

Examples of the polyol used as the raw material of the polyurethane resin may include polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, or a mixture thereof.

Examples of the isocyanate used as a raw material of the polyurethane resin include the following compounds:

toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), Naphthalene Diisocyanate (NDI), tolidine diisocyanate (TODI), Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), phenylene diisocyanate (PPDI), Xylylene Diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), cyclohexane diisocyanate, and mixtures thereof. Examples of the chain extender used as the raw material of the polyurethane resin may include difunctional low molecular weight diols such as ethylene glycol, 1, 4-butanediol and 3-methylpentanediol; trifunctional low molecular weight triols such as trimethylolpropane; and mixtures thereof. In addition, it is preferable to use a prepolymer type isocyanate compound obtained by reacting the above-mentioned various isocyanate compounds with various polyols in advance in a state where an isocyanate group is excessive and having an isocyanate group at the terminal thereof. As such an isocyanate compound, a material obtained by blocking an isocyanate group with various blocking agents such as MEK oxime can be used.

Even in the case of using any material, the polyurethane resin can be obtained by reacting a polyol and an isocyanate with each other by heating. Further, one or both of the polyol and the isocyanate have a branched structure, and the number of functional groups is 3 or more, so that the obtained polyurethane resin becomes a crosslinked polyurethane resin.

[ Cross-Linked acrylic resin ]

The crosslinked acrylic resin has high strength, but when the crosslinked acrylic resin is used alone, the surface layer may be hard and brittle.

Therefore, when the surface layer of the electrophotographic member is used as a single layer, since the surface layer has brittleness, scratches due to surface layer scratches caused by friction are easily generated. In addition, the load on the toner is easily increased by the hardness, which may cause filming.

On the other hand, in the case where the IPN structure is introduced in the vicinity of the outermost surface of the surface layer having the matrix containing the crosslinked polyurethane resin, hardness and brittleness are not easily expressed, and high strength can be applied to the surface layer while maintaining flexibility.

The crosslinked acrylic resin is formed by polymerizing an acrylic monomer. The acrylic monomer herein means not only an acrylic monomer but also a methacrylic monomer. That is, the crosslinked acrylic resin is formed by polymerizing either or both of an acrylic monomer and a methacrylic monomer.

In order to make the crosslinked acrylic resin constitute the IPN structure in the vicinity of the outermost surface of the surface layer together with the crosslinked polyurethane resin, as described above, the crosslinked polyurethane-containing resin layer is impregnated with the liquid acrylic monomer and cured, thereby forming the IPN structure.

As the acrylic monomer used herein, a polyfunctional monomer having a plurality of acryloyl groups or methacryloyl groups as functional groups is used in order to form a crosslinked structure. Meanwhile, since the viscosity of the acrylic monomer is significantly increased when the number of functional groups is 4 or more, the acrylic monomer hardly invades the surface of the resin layer formed of the crosslinked urethane resin. As a result, it is difficult to form the IPN structure. Therefore, the acrylic monomer is preferably a monomer having 2 or 3 total acryloyl groups or methacryloyl groups in one molecule, and is preferably a bifunctional acrylic monomer having 2 total acryloyl groups or methacryloyl groups in one molecule. In addition, a monofunctional monomer may be used in combination, if necessary.

The molecular weight of the acrylic monomer is preferably in the range of 200 to 750. By using a molecular weight within this range, the formation of an IPN structure becomes easy for the network structure of the crosslinked polyurethane resin, so that the strength of the surface layer can be effectively increased.

As described above, the resin layer containing the crosslinked polyurethane resin is impregnated with the acrylic monomer. For this reason, the acrylic monomer is required to have an appropriate viscosity. That is, the resin layer under the high-viscosity acrylic monomer is difficult to be impregnated with the acrylic monomer, and the impregnation state is difficult to be controlled under the low-viscosity acrylic monomer. Therefore, the viscosity of the acrylic monomer at 25 ℃ is preferably 5.0 mPas or more and 140 mPas or less.

That is, the IPN structure composed of the crosslinked polyurethane resin and the crosslinked acrylic resin can be formed by selecting one or more acrylic monomers satisfying the above molecular weight range and viscosity range, impregnating the resin layer with the acrylic monomers, and polymerizing the acrylic monomers.

The method for polymerizing the acrylic monomer is not particularly limited, and a known method can be used. Specifically, examples of the polymerization method may include a heating method or an ultraviolet irradiation method.

In various polymerization methods, known radical polymerization initiators or ionic polymerization initiators may be used.

Examples of the polymerization initiator used when heating and polymerization are carried out may include peroxides such as 3-hydroxy-1, 1-dimethylbutylperoxyneodecanoate, α -cumylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-butylperoxypivalate, t-amylperoxy-n-octanoate, t-butylperoxy-2-ethylhexyl carbonate, dicumyl peroxide, di-t-butyl peroxide, di-t-amylperoxide, 1-di (t-butylperoxy) cyclohexane and n-butyl 4, 4-di (t-butylperoxy) valerate; and

azo compounds, for example, 2-azobisbutyronitrile, 2-azobis (4-methoxy-2, 4-dimethylvaleronitrile), 2-azobis (2-methylbutyronitrile), 1-azobis (cyclohexane-1-carbonitrile), 2-azobis [2- (2-imidazolin-2-yl) propane ], 2-azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide ], 2-azobis [ N- (2-propenyl) -2-methylpropionamide ], 2-azobis (N-butyl-2-methoxypropionamide) and dimethyl-2, 2-azobis (isobutyrate).

Examples of the polymerization initiator used when the irradiation with ultraviolet rays and the polymerization are carried out may include 2, 2-methoxy-1, 2-diphenylethan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzil ] -phenyl } -2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one Ketones, 2-benzyl-2-dimethylamino-1- (4-morpholinylphenyl) -butan-1-one, 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one, bis (2,4, 6-trimethylbenzyl) -phenylphosphine oxide and 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide.

It should be noted that the polymerization initiator may be used alone, or two or more thereof may be used in combination.

In addition, when the total amount of the compound for forming the specific resin (for example, the compound having a (meth) acryloyl group) is 100 parts by mass, the amount of the polymerization initiator is preferably 0.5 parts by mass or more and 10 parts by mass or less from the viewpoint of efficiently carrying out the reaction.

It should be noted that a known apparatus may be suitably used as the heating apparatus or the ultraviolet irradiation apparatus. As a light source for radiating ultraviolet rays, an LED lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a low-pressure mercury lamp, and the like can be used. The cumulative amount of light required during polymerization can be appropriately adjusted depending on the kind or addition amount of the compound used and the polymerization initiator.

< method for measuring elastic modulus of SPM >

First, the sectional area of the electrophotographic member to be measured was cut into thin pieces using a diamond knife in a state where the temperature was kept at-110 ℃ with a cryomicrotome (trade name: EMFC6, manufactured by Leica Microsystems GmbH). In addition, samples having a square shape of 100 μm and a width in the depth direction of 100 μm were prepared from the sheet.

Here, fig. 4 shows a schematic cross-sectional view of the surface layer 44 formed on the conductive substrate 45. In the present disclosure, as shown in fig. 4, a region from the outer surface of the surface layer 44 to a depth of 0.1 μm from the outer surface of the surface layer 44, a region from a depth of 1.0 μm from the outer surface of the surface layer 44 to 1.1 μm from the outer surface of the surface layer 44, and a region from a depth of 0.5 μm from the outer surface of the surface layer 44 to 0.6 μm from the outer surface of the surface layer 44 are defined as a first region 41 in the thickness direction, a second region 42 in the thickness direction, and a third region 43 in the thickness direction, respectively. In each region appearing in a cross section of the prepared sample, the modulus of elasticity of the matrix containing the crosslinked polyurethane resin as a binder was measured. In the measurement, an SPM apparatus (trade name: MFP-3D-Origin, manufactured by Oxford Instruments) and a probe (trade name: AC160, manufactured by Olympus Corporation) were used. At this time, the force curve was measured 10 times and the arithmetic mean of 8 points excluding the maximum and minimum was obtained to calculate the elastic modulus in hertz theory. The elastic modulus of the matrix in the first, second and third regions 41, 42, 43 is E1, E2 and E3, respectively.

< method for observing Interpenetrating Polymer Network (IPN) Structure >

For the observation of the formation of the IPN structure, a method by extracting a solvent, a method of observing a shift of a glass transition point before and after the formation of the IPN structure, and the like can be used, but in the present disclosure, the observation is performed from the SPM elastic modulus and the peak top temperature of the thermal chromatogram.

In the case of forming an IPN structure, the elastic modulus is increased by entangling the polymers with each other. Therefore, the presence or absence of the IPN structure can be observed by observing the magnitude relationship of the elastic modulus in the presence or absence of the formation of the IPN structure. That is, in the present embodiment, when the elastic modulus of the outer surface and the vicinity of the outer surface (first region) having the IPN structure composed of the crosslinked polyurethane resin and the crosslinked acrylic resin and the elastic modulus from the inside of the outer surface (second region and third region) are compared with each other, the former has a higher elastic modulus.

In addition, by entangling the macromolecules, the pyrolysis temperature, i.e., the peak top temperature of the thermal chromatogram, shifts to the high temperature side. Therefore, the presence or absence of the IPN structure can be observed by observing the magnitude relationship of the peak top temperature of the thermogram in the presence or absence of the formation of the IPN structure. That is, in the present disclosure, when comparing the peak top of the crosslinked acrylic resin constituting the IPN structure together with the crosslinked urethane resin and the peak top of the crosslinked acrylic resin used alone with each other, the former has a peak top temperature existing on the high temperature side. Therefore, in the sample collected from the surface layer, when the peak top temperatures from the thermal chromatograms of the crosslinked acrylic resin before and after decomposition and removal of the crosslinked polyurethane resin are compared with each other, in the case where the peak top temperature before decomposition and removal of the crosslinked polyurethane resin is high, it can be observed that the IPN structure is formed.

A thermal chromatogram means here a mass spectrum which can be obtained by microsampling mass spectrometry and is referred to as ion chromatography. An overview of micro-sampling mass spectrometry will be described below.

< micro-sampling Mass Spectrometry >

First, similarly to the measurement of elastic modulus of SPM, a sample was prepared by slicing the region to be measured of the electrophotographic member with a cryostat. Specifically, samples each having a square shape of 100 μm and a width in the depth direction of 0.1 μm were prepared from the first to third regions of the surface layer. In the measurement, for example, an ion trap type mass spectrometer ("Polaris Q" (trade name, manufactured by Thermo Electron Corporation)) mounted on a gas chromatography mass spectrometer was used. The sample is fixed to a filament disposed at the end of the probe and introduced directly into the ionization chamber. Subsequently, the sample was rapidly heated from room temperature to 1,000 ℃ at a constant heating rate.

The sample is decomposed by heating, and the evaporated sample is ionized by irradiation with an electron beam and detected by a mass spectrometer. At this time, under the condition of a constant heating rate, a thermogram similar to that in thermogravimetric analysis-mass spectrometry (TG-MS) and having a mass spectrum called Total Ion Chromatography (TIC) was obtained.

In addition, since a thermal chromatogram with respect to a filament having a predetermined mass can also be obtained, a peak top temperature of the thermal chromatogram corresponding to a decomposition temperature of a predetermined high molecular structure can be obtained. The peak top temperature of the thermal chromatogram has a correlation with the crosslinked structure in the resin structure. As the crosslinking density increases, the peak top temperature shifts to the high temperature side.

In the electrophotographic member of the present embodiment, the IPN structure composed of the crosslinked polyurethane resin and the crosslinked acrylic resin is formed in the vicinity of the outermost surface of the surface layer, so that the crosslinked polyurethane resin and the crosslinked acrylic resin are kept close to each other even in a high-temperature environment. Therefore, since the interaction of intermolecular forces between the crosslinked polyurethane resin and the crosslinked acrylic resin can be exhibited even in a high-temperature environment, scratches due to surface scratches caused by friction can be suppressed even in a high-temperature environment.

Since the crosslinked urethane resin constitutes an IPN structure together with the crosslinked acrylic resin, the crosslinking density in the vicinity of the crosslinked urethane resin becomes relatively high, making the outer surface of the surface layer stronger. As a result, the effect of suppressing scratches due to surface layer scratches increases.

Therefore, the electrophotographic member of the present embodiment is an electrophotographic member including a conductive substrate and a surface layer having a single-layer structure, wherein the surface layer has a matrix containing a crosslinked urethane resin as a binder.

When the modulus of elasticity of the matrix in the first region of the surface layer in the thickness direction is defined as E1 and the modulus of elasticity of the matrix in the second region from a depth of 1.0 μm from the outer surface of the surface layer to 1.1 μm from the outer surface of the surface layer in the thickness direction is defined as E2, E1 and E2 satisfy the following formulas (1) and (2), respectively. In this case, the flexibility of the surface layer can be sufficiently maintained while the high strength of the outer surface of the surface layer is effectively maintained, so that scratches and filming due to scratching of the surface layer can be further suppressed at a high level.

E1≥200MPa (1)

10MPa≤E2≤100MPa (2)

In addition, when the elastic modulus of the matrix in the third region from a depth of 0.5 μm from the outer surface of the surface layer to 0.6 μm from the outer surface of the surface layer in the thickness direction is defined as E3, E3 is measured in the cross section of the surface layer, and E1 and E3 preferably satisfy the relationship represented by the following formula (3). When E1 and E3 satisfy the relationship represented by formula (3), the flexibility of the surface layer can be sufficiently maintained while effectively maintaining the high strength of the outer surface of the surface layer, so that scratches and filming due to surface layer scratching can be further suppressed at a high level.

(E1-E3)/E3>1 (3)

The surface layer of the present embodiment contains a crosslinked acrylic resin so that the crosslinked acrylic resin constitutes an IPN structure together with the crosslinked urethane resin, and effectively increases the strength of the outer surface of the surface layer. As a result, scratches and filming due to surface layer scratching can be further suppressed at a high level.

The fact that the crosslinked acrylic resin of the present embodiment constitutes an IPN structure together with the crosslinked polyurethane resin can be observed by the difference in peak top temperature of the thermal chromatogram obtained from the filaments of the crosslinked acrylic resin before and after decomposing and removing the crosslinked polyurethane resin in the composition. That is, the peak top temperature from the thermal chromatogram of the crosslinked acrylic resin, which is measured from the first sample sampled from the above-mentioned first region, is defined as a1(° c).

In addition, the peak top temperature obtained from the thermal chromatogram of the crosslinked acrylic resin, which is measured from the second sample obtained by decomposing the crosslinked polyurethane resin contained in the first sample, is defined as a2(° c). When a1 and a2 satisfy the relationship represented by the following formula (4), the strength of the outer surface of the surface layer is effectively increased, so that scratches and filming due to surface layer scratching can be further suppressed at a high level, which is preferable.

A1>A2 (4)

Further, in the electrophotographic member of the present embodiment, the above-described first region and second region of the surface layer preferably satisfy the relationship represented by the following formula (5).

T1>T2 (5)

In formula (5), T1 is the peak top temperature (c) of the thermal chromatogram obtained for the crosslinked polyurethane resin in the first region, and T2 is the peak top temperature (c) of the thermal chromatogram obtained for the crosslinked polyurethane resin contained in the second region. When T1 and T2 satisfy the relationship represented by the following formula (5), the strength of the outer surface of the surface layer is effectively increased, so that scratches and filming due to surface layer scratching can be further suppressed at a high level.

Further, when T1 and T2 satisfy the relationship represented by the following formula (6), the IPN structure is appropriately constituted by a crosslinked acrylic resin, so that the strength of the outer surface can be sufficiently maintained, which is more preferable.

(T1-T2)>1.0 (6)

The present disclosure aims to achieve suppression of generation of scratches due to scratching of the surface of a member for electrophotography when a plurality of images are formed in a high-temperature environment, and suppression of occurrence of contamination by toner, that is, filming. Therefore, the IPN structure made of a crosslinked acrylic resin or the like is preferably formed in the vicinity of the outermost surface of the surface layer. This is because such a configuration can further reduce the load on the toner. Therefore, T1, T2, and T3 preferably satisfy the relationships represented by the following formulas (7) and (8).

T1>T3 (7)

|T1-T3|>|T3-T2| (8)

Here, T1 and T2 are the above meanings, and T3 is the peak top temperature of the thermal chromatogram of the crosslinked polyurethane resin obtained from the above third region. When T1, T2, and T3 satisfy the relationships represented by equations (7) and (8), it is shown that the IPN structure is formed in most of the surface layer at a depth of less than 1 μm from the surface of the surface layer. Therefore, the generation of scratches and the occurrence of film formation due to the surface layer scratching can be suppressed at a high level.

When the above surface layer contains one or more of the modified silicone compound and the modified fluorine compound, the acrylic monomer stays near the outer surface, so that an IPN structure can be locally formed near the outermost surface. In addition, the penetration of the acrylic monomer into the depth of the surface layer can be suppressed, and the surface layer can be kept appropriately flexible. Therefore, the generation of scratches and the occurrence of film formation due to the surface layer scratching can be further suppressed at a high level.

The monomer forming the crosslinked acrylic resin is a polyfunctional monomer having a plurality of acryloyl groups or methacryloyl groups as functional groups. The total number of acryloyl or methacryloyl groups in one molecule is preferably 2 or 3. In this case, since the monomer effectively stays in the vicinity of the outer surface, the IPN structure is locally formed on the outermost surface side, and the generation of scratches and the occurrence of film formation due to surface layer scratching can be suppressed at a high level.

[ Filler ]

In addition, the surface layer may further contain a filler in order to increase the reinforcing effect of the surface layer.

Examples of the insulating filler may include the following fillers: fine quartz powder, silica particles, diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, glass fiber, organic reinforcing agent, and organic filler. The surface of the filler may be hydrophobized by an organosilicon compound, such as a polydiorganosiloxane. As the insulating filler, silica particles are preferably used because the silica particles are uniformly dispersed in the surface layer. Among the silica particles, silica particles subjected to a hydrophobic surface treatment are particularly preferably used. The content of the silica particles is preferably 0.5 mass% or more and 20 mass% or less with respect to 100 parts by mass of the resin component forming the surface layer.

In view of the reinforcing property and conductivity of the surface layer, the number average primary particle diameter of the silica particles is preferably in the range of 10nm or more and 120nm or less, more preferably in the range of 15nm or more and 80nm or less, and particularly preferably in the range of 15nm or more and 40nm or less. The number average primary particle diameter was measured as follows. The silica particles were observed with a scanning electron microscope, and 100 particles in the field of view were measured to obtain an average particle diameter.

Examples of the conductive filler may include the following fillers: carbon-based substances such as carbon black or graphite; metals or alloys, such as aluminum, silver, gold, tin-lead alloys or copper-nickel alloys; metal oxides such as zinc oxide, titanium oxide, aluminum oxide, tin oxide, antimony oxide, indium oxide, or silver oxide; and substances obtained by conducting metal plating with copper, nickel or silver on various fillers. As the conductive filler, carbon black is particularly preferably used in terms of easy control of conductivity and low price. Among them, carbon black having a relatively small primary particle diameter and tending to be hydrophobic is particularly preferably used from the viewpoint of uniform dispersion in the surface layer. The number average primary particle diameter of the carbon black is preferably in the range of 20nm or more and 60nm or less in view of the reinforcing property and conductivity of the surface layer. In the surface properties of carbon black, the pH of carbon black is preferably 3.0 or more and 8.0 or less. The content of carbon black is preferably 5 mass% or more and 45 mass% or less with respect to 100 parts by mass of the resin component forming the surface layer.

[ other Components ]

In addition, the surface layer may contain various additives such as a crosslinking agent, a crosslinking aid, a plasticizer, a filler, an extender, a vulcanizing agent, a vulcanization aid, an antioxidant, an age resistor, a processing aid, a dispersant and a leveling agent in addition to the components described within a range that does not impair the function of the surface layer.

Electrophotographic process cartridge and electrophotographic image forming apparatus

An electrophotographic image forming apparatus of the present disclosure is an apparatus including: an image carrier bearing an electrostatic latent image; a charging device for charging the image carrier at a time; an exposure device that forms an electrostatic latent image on the primarily charged image carrier; a developing device that develops the electrostatic latent image with toner and forms a toner image; a transfer device that transfers the toner image onto a transfer material. Fig. 2 is a schematic sectional view illustrating an electrophotographic image forming apparatus according to an embodiment of the present disclosure.

Fig. 3 is an enlarged sectional view of a process cartridge mounted in the electrophotographic image forming apparatus of fig. 2. The process cartridge includes an image carrier 21 such as a photosensitive drum, a charging device including a charging member 22, a developing device including a developing member 24, and a cleaning device including a cleaning member 30. In addition, the process cartridge is configured to be detachably mounted to the main body of the electrophotographic image forming apparatus of fig. 2.

The image carrier 21 is uniformly charged (primary charged) by a charging member connected to a bias power source (not shown). At this time, the charging potential of the image carrier 21 is-800V or more and-400V or less. Next, the image carrier 21 is irradiated with exposure light 23 by an exposure device (not shown) to form an electrostatic latent image, thereby forming an electrostatic latent image on the surface thereof. As the exposure light 23, LED light or laser light can be used. The surface potential of the exposed portion of the image carrier 21 is-200V or more and-100V or less.

Next, the toner negatively charged by the developing member 24 is applied (developed) onto the electrostatic latent image, and a toner image is formed on the image carrier 21. Thus, the electrostatic latent image is converted into a visible image. At this time, a voltage of-500V or more and-300V or less is applied to the developing member 24 by a bias power source (not shown). Note that the developing member 24 is in contact with the image carrier 21 at a nip width of 0.5mm or more and 3mm or less.

In the process cartridge according to the embodiment of the present disclosure, the toner supply roller 25 is in contact with the developing member 24 in a rotatable state on the upstream side of the rotation of the developing member 24 with respect to the contact portion between the developing blade 26 (which is a toner regulating member) and the developing member 24.

The toner image developed on the image carrier 21 is primarily transferred onto the intermediate transfer belt 27. The primary transfer member 28 is in contact with the back surface of the intermediate transfer belt 27. By applying a voltage of +100V or more and +1,500V or less to the primary transfer member 28, the negatively charged toner image is primarily transferred from the image carrier 21 to the intermediate transfer belt 27. Primary transfer member 28 may be roller-shaped or blade-shaped.

In the case where the electrophotographic image forming apparatus is a full-color image forming apparatus, the above-described charging, exposure, development, and primary transfer steps are performed with respect to each of yellow, cyan, magenta, and black colors. For this reason, in the electrophotographic image forming apparatus shown in fig. 2, four process cartridges storing the respective color toners are detachably attached to the main body of the electrophotographic image forming apparatus. The above-described charging, exposure, development, and primary transfer steps are sequentially performed at predetermined time intervals. In this way, a 4-color toner image displaying a full-color image is superimposed on the intermediate transfer belt 27.

The toner image on the intermediate transfer belt 27 is transferred to a position facing the secondary transfer member 29 by the rotation of the intermediate transfer belt 27. The recording paper is conveyed along the recording paper conveying path 32 between the intermediate transfer belt 27 and the secondary transfer member 29 at a predetermined timing. By applying a secondary transfer bias to the secondary transfer member 29, the toner image on the intermediate transfer belt 27 is transferred onto the recording paper. At this time, the bias to be applied to the secondary transfer member 29 is +1,000V or more and +4,000V or less. The recording paper on which the toner image is transferred by the secondary transfer member 29 is conveyed to a fixing device 31. The toner image on the recording paper is fused and fixed on the recording paper, and then the recording paper is discharged out of the electrophotographic image forming apparatus, thereby completing the printing operation.

The toner remaining on the image carrier 21, which is not transferred from the image carrier 21 to the intermediate transfer belt 27, is scraped off by a cleaning member 30 for cleaning the surface of the image carrier 21, thereby cleaning the surface of the image carrier 21.

According to an aspect of the present disclosure, an electrophotographic member having extremely high durability can be provided. In addition, according to another aspect of the present disclosure, a process cartridge that contributes to stable formation of high-quality electrophotographic images can be obtained. Further, according to still another aspect of the present disclosure, an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image can be obtained.