CN117311112A

CN117311112A - Electrophotographic member, process cartridge, and electrophotographic image forming apparatus

Info

Publication number: CN117311112A
Application number: CN202310779939.1A
Authority: CN
Inventors: 佐佐木步未; 长冈一聪
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2022-06-29
Filing date: 2023-06-29
Publication date: 2023-12-29

Abstract

The invention relates to an electrophotographic member, a process cartridge, and an electrophotographic image forming apparatus. Provided is an electrophotographic member including: a conductive substrate; and an elastic layer on the substrate, the elastic layer being composed of a single layer, the elastic layer comprising a silicone rubber having a dimethylsiloxane structure, wherein when a peak top temperature derived from the dimethylsiloxane structure in an ion thermogram measured from a first sample sampled from a first region having a thickness of 0.5 μm from the first surface toward the second surface is represented by T1, and a peak top temperature derived from the dimethylsiloxane structure in an ion thermogram measured from a second sample sampled from a second region corresponding to a thickness of 1.0 μm to 1.5 μm from the second surface toward the first surface is represented by T2, T1 and T2 satisfy a relationship of T1 > T2.

Description

Electrophotographic member, process cartridge, and electrophotographic image forming apparatus

Technical Field

The present disclosure relates to an electrophotographic member incorporated into an apparatus employing an electrophotographic system. The present disclosure also relates to a process cartridge and an electrophotographic image forming apparatus each using the electrophotographic member.

Background

In an electrophotographic image forming apparatus, an image bearing member is charged by a charging member, and an electrostatic latent image is formed thereon by exposure light. Next, the toner in the developer container is applied to the developing member through the toner supply member and the toner regulating member, and in a portion where the image bearing member and the developing member contact each other or an area near the portion, the electrostatic latent image formed on the image bearing member is developed with the toner. Thereafter, the toner on the image bearing member is transferred onto the recording paper by the transfer unit, and is fixed by heat and pressure. Further, the toner remaining on the image bearing member even after transfer is removed by the cleaning blade.

Electrophotographic members used in such electrophotographic image forming apparatuses, such as a developing member, a charging member, a toner supplying member, and a toner regulating member, are each required to have characteristics that do not degrade the performance of the initial state even after long-term use, i.e., excellent durability. Further, with the recent demand for low power consumption, toners that can be fixed even at low temperatures have begun to be used. Such toner is relatively susceptible to deterioration. Therefore, further suppression of deterioration of the toner is also required.

In view of the above, in order to further suppress deterioration of the toner, a soft silicone rubber is sometimes used in such an electrophotographic member from the viewpoint of further reducing stress on the toner. The siloxane bond in the main chain of the silicone rubber has a helical structure, and the helical structure peculiar to the silicone rubber exhibits various characteristics which are not observed in an organic polymer in which the main chain is formed of a c—c bond. Therefore, silicone rubber has stable rubber elasticity over a wider temperature range than natural rubber and any other synthetic rubber, and has excellent heat resistance and cold resistance. Meanwhile, silicone rubber has yet to be improved in terms of abrasion resistance.

Japanese patent application laid-open No. h04-76577 discloses a silicone rubber elastomer having improved abrasion resistance by mixing a silicone rubber with a silane coupling agent, and a developing member using the elastomer.

Disclosure of Invention

At least one aspect of the present disclosure is directed to providing an electrophotographic member that can simultaneously achieve both suppression of abrasion of its surface and suppression of toner deterioration at a higher level even when used for formation of an electronic image under a high-temperature and high-humidity environment for a long period of time. Further, at least one aspect of the present disclosure is directed to providing a process cartridge that facilitates stable formation of high-quality electrophotographic images. Further, at least one aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images.

According to at least one aspect of the present disclosure, there is provided an electrophotographic member comprising: a conductive substrate; and an elastic layer on the substrate, wherein the elastic layer is composed of a single layer. The elastic layer comprises a silicone rubber having a dimethylsiloxane structure. When a side of the elastic layer facing the substrate is defined as a second surface, a surface of the elastic layer opposite to the second surface is defined as a first surface, and when a peak top temperature derived from a dimethylsiloxane structure in an ion thermogram (ion thermogram) measured from a first sample sampled from the first surface toward a first region of a thickness of 0.5 μm is represented by T1 (°c), and a peak top temperature derived from a dimethylsiloxane structure in an ion thermogram measured from a second sample corresponding to a second region of a thickness of 1.0 μm to 1.5 μm from the second surface of the elastic layer toward the first surface is represented by T2 (°c), T1 and T2 satisfy a relationship represented by the following formula (1):

formula (1) T1> T2.

Further, according to at least one aspect of the present disclosure, there is provided a process cartridge detachably mountable to a main body of an electrophotographic image forming apparatus, the process cartridge including the above-described electrophotographic member.

Further, according to at least one aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including: an image bearing member for bearing an electrostatic latent image; charging means for charging the image bearing member once; an exposure device for forming an electrostatic latent image on the primary charged image bearing member; a developing member for developing the electrostatic latent image with toner to form a toner image; and a transfer device for transferring the toner image onto a transfer material, wherein the developing member is the above 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. 1 is a conceptual diagram illustrating an example of an electrophotographic member according to one aspect of the present disclosure.

Fig. 2 is a schematic configuration diagram showing an example of a process cartridge according to an aspect of the present disclosure.

Fig. 3 is a schematic configuration diagram showing an example of an electrophotographic image forming apparatus according to an aspect of the present disclosure.

Fig. 4 is a schematic diagram showing an example of a cross section of an electrophotographic member according to one aspect of the present disclosure.

Detailed Description

The present inventors have studied a developing roller using a silicone rubber material according to the invention described in Japanese patent application laid-open No. H04-76577. As a result, although the developing roller exhibits excellent abrasion resistance, when the roller is used to form many electrophotographic images under a high-temperature and high-humidity environment, filming caused by deteriorated toner appears on the outer surface (toner bearing surface) of the developing roller in some cases, resulting in degradation of the quality of each electrophotographic image.

The occurrence of filming on the outer surface of the developing roller may be caused by the increase in hardness of the silicone rubber according to the invention described in japanese patent application laid-open No. h04-76577 by the action of the silane coupling agent. That is, the present inventors speculate that filming occurs on the outer surface of the developing roller because the toner is subjected to greater stress from the developing roller due to an increase in the hardness of the elastic layer of the roller including the silicone rubber, and thus deterioration of the toner is accelerated.

In view of the above, the present inventors have studied in order to obtain a developing roller having a surface with improved abrasion resistance while suppressing an increase in stress applied to the toner. As a result, the present inventors have found that the following is effective for achieving both maintenance of flexibility of an elastic layer including a silicone rubber including a dimethylsiloxane structure and improvement of abrasion resistance of an outer surface of the elastic layer: the molecular mobility (molecular mobility) of the silicone rubber in a region (hereinafter also simply referred to as "surface region") having a thickness of 0.5 μm in the depth direction thereof from the outer surface is made lower than that of the silicone rubber present in a region deeper than the surface region.

That is, an electrophotographic member according to at least one aspect of the present disclosure includes a conductive substrate and an elastic layer disposed on the substrate. The elastic layer is composed of a single layer, i.e., a single layer elastic layer. The elastic layer includes a silicone rubber including a dimethylsiloxane structure. When a side of the elastic layer facing the substrate is defined as a second surface and a surface of the elastic layer opposite to the second surface is defined as a first surface, when a peak top temperature derived from a dimethylsiloxane structure in an ion thermogram measured from a first sample sampled from a first region (surface region) of a thickness of 0.5 μm from the first surface toward the second surface is represented by T1 (°c), and a peak top temperature derived from a dimethylsiloxane structure in an ion thermogram measured from a second sample corresponding to a thickness of 1.0 μm to 1.5 μm from the second surface toward the first surface of the elastic layer is represented by T2 (°c), T1 and T2 satisfy a relationship represented by the following formula (1):

Formula (1) T1> T2.

An electrophotographic member according to at least one embodiment of the present disclosure is described below with reference to the accompanying drawings.

Fig. 1 is a circumferential cross-sectional view of an electrophotographic member including a conductive base 2 and an elastic layer 1 on the outer peripheral surface of the base. The elastic layer 1 and the conductive substrate 2 have the same meaning as the elastic layer 44 and the conductive substrate 45 shown in fig. 4, respectively. The side of the elastic layer 44 facing the conductive substrate 45 is defined as a second surface 47, and the surface of the elastic layer 44 opposite to the second surface 47 is defined as a first surface 46. In addition, in the present disclosure, as shown in fig. 4, a region of a thickness ranging from the first surface 46 toward the second surface 47 up to 0.5 μm is defined as the first region 41. In addition, a region having a thickness of 1.0 μm to 1.5 μm from the second surface 47 toward the first surface 46 is defined as the second region 42. Further, a region corresponding to a thickness of 10.0 μm to 10.5 μm from the first surface 46 toward the second surface 47 is defined as the third region 43.

An electrophotographic member according to at least one embodiment of the present disclosure includes a conductive substrate 2 and a single-layer elastic layer 1 on the substrate. The elastic layer includes a silicone rubber including a dimethylsiloxane structure. Here, the peak top temperature derived from the dimethylsiloxane structure in the ion thermogram measured from the first sample sampled from the first region 41 is represented by T1 (°c). Similarly, the peak top temperature from the dimethylsiloxane structure in the ion thermogram, which is measured from the second sample sampled from the second region 42, is represented by T2 (°c). The elastic layer according to the present embodiment satisfies the relationship represented by the following formula (1) for T1 and T2:

Formula (1) T1> T2.

In the elastic layer satisfying the formula (1), the difference "T1-T2" preferably falls within a range of 3.3 ℃ to 9.1 ℃, more preferably falls within a range of 3.3 ℃ to 6.1 ℃. In addition, T1 preferably falls within the range of 468.1 ℃ to 470.8 ℃.

Although the thickness of the elastic layer satisfying the formula (1) is not particularly limited, the thickness is preferably set to 0.1mm to 6.0mm, particularly preferably 0.3mm to 6.0mm, more preferably 1.0mm to 6.0mm, from the viewpoint of achieving both of the relaxation of stress applied to the toner and the prevention of abrasion of the outer surface thereof at a higher level.

For example, an ion trap mass spectrometer (ion trap-type mass spectrometer) (product name: polar Q; manufactured by Thermo Fisher Scientific, inc.) may be used for measurement of peak top temperature of an ion thermogram.

First, the corresponding measurement regions are each sliced into a sheet by a microtome, and a measurement sample is cut out of the sheet. The resulting measurement sample was fixed to a filament at the tip of the Direct Exposure probe of the mass spectrometer and inserted directly into its ionization chamber. Thereafter, the sample was rapidly heated from room temperature to a temperature of 700 ℃ at a constant heating rate. The sample decomposed by heating and evaporated is ionized by electron beam irradiation, and detected by a mass spectrometer. At this time, a thermogram similar to the thermogram of thermogravimetry-mass spectrometry (TG-MS) method having a mass spectrum called Total Ion Thermogram (TIT) is obtained under the condition that the heating rate is constant.

Materials can be identified from the resulting thermograms using, for example, data acquisition and analysis software (product name: xcalibur; manufactured by Thermo Fisher Scientific, inc.). In addition, an ion thermogram of fragments of a predetermined mass can be obtained, and thus a peak top temperature of the ion thermogram corresponding to a decomposition temperature of a desired molecular structure can be obtained. For the same molecular structure, a shift in the peak top temperature of the ion thermogram to a higher temperature means that decomposition of the molecular structure does not occur unless its temperature is raised to a higher value. This phenomenon may be caused, for example, by a decrease in molecular mobility of the polymer having the molecular structure.

The fact that Tl is greater than T2 when the foregoing is applied to the elastic layer according to the present disclosure means that the molecular mobility of the silicone rubber in the first region is reduced compared to the molecular mobility of the silicone rubber in the second region. Thus, an elastic layer having an outer surface with improved abrasion resistance while maintaining flexibility of the silicone rubber can be obtained.

The method of making the molecular mobility of the silicone rubber in the first region lower than that of the silicone rubber in the second region includes, for example, at least one method selected from the group consisting of: a method comprising increasing the degree of crosslinking of the silicone rubber in the surface region; and methods involving surrounding the circumference of the silicone rubber molecule in the surface region with any other polymer.

A method of obtaining an elastic layer in which the crosslinking degree of the silicone rubber in the surface region is higher than that in a region deeper than the surface region is, for example, a method including applying an Electron Beam (EB) from the outer surface side of the silicone-containing rubber layer that should be used as the elastic layer.

In addition, examples of the method of obtaining an elastic layer in which the periphery of the silicone rubber in the surface region is surrounded with any other polymer include: a method comprising impregnating a liquid containing other polymer in a dissolved state from an outer surface of a silicone-containing rubber layer which should be used as an elastic layer; and a method comprising impregnating a silicone-containing rubber layer with a liquid containing a raw material (e.g., a monomer, an oligomer, or a prepolymer) for other polymers, and then curing the raw material. Each of these methods may also be referred to hereinafter as "impregnation methods".

As described above, examples of the impregnation method include: impregnating a monomer used as a raw material for other polymers from an outer surface of the silicone-containing rubber layer in a region corresponding to the surface region; the monomers of the corresponding region are cured. The surface area of the elastic layer obtained as a result of the above contains silicone rubber and a polymer different from the silicone rubber. Meanwhile, in at least a part of the region deeper than the surface region of the elastic layer, there is no polymer derived from the monomer because the monomer is not impregnated therein even by the above-described impregnation treatment.

That is, the electrophotographic member according to one embodiment of the present disclosure obtained by the dipping method satisfies the above condition represented by formula (1), and the first sample contains the polymer not contained in the second sample. The peak top temperature of the polymer-derived in the ion thermogram, which was measured from the first sample, was represented by C1 (°c). In addition, the peak top temperature derived from the polymer in the ion thermogram is represented by C2 (°c), which is measured from a third sample obtained by decomposing the silicone rubber in the first sample. In the electrophotographic member according to one embodiment of the present disclosure, C1 and C2 preferably satisfy the relationship represented by the following formula (2):

formula (2) C1> C2.

In the elastic layer satisfying the formula (2) in addition to the formula (1), C1 preferably falls within a range of 414.2 ℃ to 423.4 ℃, the difference "C1-C2" preferably falls within a range of 0.9 ℃ to 3.6 ℃, and T1 preferably falls within a range of 468.1 ℃ to 470.8 ℃. In addition, the difference "T1-T2" preferably falls within the range of 3.3℃to 9.1℃and more preferably falls within the range of 3.3℃to 6.1 ℃.

Although the thickness of the elastic layer satisfying the formulas (1) and (2) is not particularly limited, the thickness is preferably set to 0.1mm to 6.0mm, particularly preferably 0.3mm to 6.0mm, more preferably 1.0mm to 6.0mm, from the viewpoint of achieving both of the alleviation of the stress applied to the toner and the prevention of the abrasion of the outer surface thereof at a higher level.

Examples of the method of decomposing the silicone rubber include a Tetraethoxysilane (TEOS) method, an alkali fusion method, a fluorosilyl method, and a Methyl Orthoformate (MOF) decomposition method each including selectively decomposing a siloxane bond of the silicone rubber. When the dimethylsiloxane structure derived from the silicone rubber is removed by any one of these methods, a third sample containing the polymer from which the dimethylsiloxane structure has been removed can be obtained.

The peak top temperatures in the ion thermogram derived from the polymer are each related to the degree of crosslinking of the polymer. Therefore, the fact that C1 before silicone rubber removal is higher than C2 after silicone rubber removal means that the degree of crosslinking of the polymer before the dimethylsiloxane structure removal is higher than that of the polymer after the dimethylsiloxane structure removal, or in other words, the hardness of the polymer before the dimethylsiloxane structure removal is higher than that of the polymer after the dimethylsiloxane structure removal.

Therefore, when the relationship represented by the above formula (1) and formula (2) is satisfied at the same time, the polymer can enter into the network structure and the helix structure between molecules of the silicone polymer for forming the elastic layer. This shows that, as a result of the above, an interpenetrating polymer network structure in which the respective network structures of the silicone rubber and the polymer are entangled and intertwined with each other without being bonded to each other by covalent bonds is formed. The interpenetrating polymer network structure is hereinafter referred to as "IPN structure".

An interpenetrating polymer network structure (IPN structure) is defined as a structure in which network structures of two or more kinds of high molecular compounds are entangled and intertwined with each other without being bonded to each other by covalent bonds. There is no chemical bond between the materials used to form the IPN structure and therefore the properties of each material are not compromised. At the same time, it is desirable to increase the strength of the structure by entanglement of the materials with each other.

The IPN structure in the elastic layer according to this aspect is formed by the polymer into a network of three-dimensional cross-linked structures of the silicone rubber. The IPN structure is not loosened unless the molecular chain of the high molecular compound used to form its network is cleaved. Examples of methods of forming the IPN structure may include several methods. For example, a method called a sequential network formation method below can be employed: preforming a network of a polymer of a first component; then, swelling the polymer with the monomer of the second component and the polymerization initiator as needed; then, a network of a polymer of the second component is formed. Alternatively, for example, the following simultaneous network formation method may be employed: the monomer of the first component and the monomer of the second component having different reaction mechanisms from each other, and the polymerization initiator for the respective monomers are mixed, and the respective monomers are polymerized simultaneously to form their network structures.

There is substantially no covalent bond between the silicone rubber as the first component and the polymer of the second component forming the IPN structure, so the rubber elasticity of the structure is not compromised. At the same time, it is desirable to improve the strength of the silicone rubber by entanglement of the silicone rubber and the polymer of the second component with each other. Furthermore, the properties of the helical structure and the IPN structure specific to silicone rubber may be combined with each other to exhibit a synergistic effect.

Thus, due to the silicone rubber, the elastic layer can maintain flexibility inside thereof, while the elastic layer is hardened only at its extremely outermost surface by the formation of the IPN structure. As a result, it is conceivable that the elastic layer can achieve both further improvement in abrasion resistance and reduction in stress applied to the toner by the electrophotographic member.

In addition, in the formation of the IPN structure, a silicone rubber containing a silicone polymer having a more uniform molecular weight as a main component is preferably used. When the IPN structure is formed in the silicone rubber, the monomer of the second component more easily penetrates the silicone rubber more uniformly, and thus the monomer of the second component more easily enters the network structure of the silicone rubber than in the case where the IPN structure is formed in a silicone rubber having a molecular weight that is not uniform. As a result, molecular movement of the silicone rubber can be uniformly restricted, and therefore shaving (shaving) of the electrophotographic member and filming on the surface thereof can be suppressed at a higher level.

Preferred examples of the polymer of the second component include acrylic resins, epoxy resins, and polyurethane resins. Although polymeric materials such as acrylic, epoxy, and polyurethane resins each generally have high strength, each of these materials may be hard and brittle when used alone.

Therefore, when the polymer is used as a single-layer film in the surface layer of the electrophotographic member, the polymer is easily abraded by friction to cause shaving due to brittleness thereof. Further, since the polymer has high hardness, the polymer may be a cause of deterioration and filming of the toner, and thus the load on the toner tends to become large. Meanwhile, when the polymer and the silicone rubber having a spiral structure are introduced as an IPN structure, the hardness and brittleness of the polymer hardly show because the crystallinity thereof is broken.

Various resin materials and a method of impregnating these materials into the elastic layer of the electrophotographic member are described below. The impregnating treatment liquid containing the monomer components for each resin is referred to as "impregnating treatment liquid".

(1) Acrylic resin

The acrylic resin is, for example, a resin containing a structural unit derived from a (meth) acryloyl group represented by structural formula (I):

Structural formula (I)

In the structural formula (I), A represents a hydrogen atom or a methyl group, and G represents-O-R ¹ or-NR ² R ³ ，R ¹ 、R ² And R ³ Each independently represents a hydrogen atom or an organic group, and R ² And R is ³ May be interconnected to form a ring.

The presence of the structural formula (I) can be judged by detecting the presence or absence of a compound derived from a (meth) acryloyl group by a general mass spectrometry such as pyrolysis GC/MS.

The acrylic resin is formed by polymerization of one or both of an acrylic monomer and a methacrylic monomer. In this specification, the term "acrylic" and the term "methacrylic" may be collectively referred to as "(meth) acrylic". Similarly, the term "acryl" and the term "methacryl" may be collectively referred to as "(meth) acryl".

In order to form a crosslinked structure, a polyfunctional monomer having a plurality of acryl groups or methacryl groups as its functional groups is preferable as the acrylic monomer. Meanwhile, when the number of functional groups is 4 or more, the viscosity of the acrylic monomer becomes so high that it is difficult for the monomer to penetrate the surface of the elastic layer including silicone rubber, and as a result, it is difficult to form an IPN structure. Therefore, as the acrylic monomer, monomers having a total of 2 or 3 acryl groups and methacryl groups present in one molecule are preferable, and a more preferable example thereof is a difunctional acrylic monomer having 2 such groups.

The molecular weight of the acrylic monomer preferably falls within the range of 200 to 750. When an acrylic monomer having a molecular weight in this range is used, an IPN structure is easily formed for a network structure of silicone rubber, so that the strength of the elastic layer can be effectively improved.

As described above, in the production process of the electrophotographic member according to the present disclosure, the acrylic monomer is impregnated in the elastic layer containing the silicone rubber. For this reason, the acrylic monomer preferably has a viscosity capable of being impregnated in silicone rubber. Specifically, for example, the viscosity of the impregnation treatment liquid containing the acrylic monomer at a temperature of 25 ℃ is preferably 5.0mpa·s to 140mpa·s.

Any solvent may be freely selected as the solvent of the impregnation treatment liquid as long as the solvent satisfies both affinity for the elastic layer and solubility for the acrylic monomer. Examples thereof include: alcohols such as methanol, ethanol, and n-propanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters such as methyl acetate and ethyl acetate.

The IPN structure of silicone rubber and acrylic resin can be formed by: impregnating the elastic layer with one or more selected acrylic monomer impregnating solutions each satisfying the above molecular weight range and viscosity range; and polymerizing the monomer.

The method of polymerizing the acrylic monomer is not particularly limited, and known methods may be used. Specific examples thereof include thermal polymerization based on heating and photopolymerization based on ultraviolet irradiation.

Known radical polymerization initiators or ionic polymerization initiators may be used for each polymerization process. Thus, the impregnating treatment solution to be used comprises an acrylic monomer and any such polymerization initiator.

The thermal polymerization initiator when thermal polymerization is performed is, for example: peroxides, such as 3-hydroxy-1, 1-dimethylbutyl peroxyneodecanoate, α -cumyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, t-butyl peroxypivalate, t-amyl peroxyn-octanoate, t-butyl peroxy2-ethylhexyl carbonate, dicumyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, 1-di (t-butyl peroxycyclohexane, or n-butyl-4, 4-di (t-butyl peroxyl) pentanoate; or azo compounds, such as 2, 2-azobisisobutyronitrile, 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, 2-azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide ], 2-azobis [ N- (2-propenyl) -2-methylpropionamide ], 2-azobis (N-butyl-2-methoxypropionamide), or dimethyl-2, 2-azobis (isobutyrate).

Photopolymerization initiators when carrying out photopolymerization based on ultraviolet irradiation are, for example, 2-dimethoxy-1, 2-diphenyl-1-ethanone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propanone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl ] -phenyl } -2-methyl-1-propanone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) -1-butanone, bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide or 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide.

These polymerization initiators may be used alone or in combination.

Further, regarding the blending amount of the polymerization initiator, when the total amount of the compounds (for example, the compound having a (meth) acryloyl group) for forming a specific resin is defined as 100 parts by mass, the amount of the initiator is preferably 0.5 parts by mass to 10 parts by mass from the viewpoint of efficiently conducting the reaction of resin formation.

As the means for heating or the means for ultraviolet irradiation, known means can be suitably used. For example, an LED lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, and a low-pressure mercury lamp may each be used as a light source for applying ultraviolet light. The amount of accumulated light required for polymerization can be appropriately adjusted depending on the kind and the addition amount of the compound and the polymerization initiator used.

(2) Epoxy resin

The epoxy resin is, for example, a resin having a group derived from an epoxy group represented by the structural formula (II).

Structural formula (II)

The presence of structural formula (II) can be judged by detecting the presence or absence of a compound derived from an epoxy group by a general mass spectrometry such as pyrolysis GC/MS.

The epoxy resin is preferably a polymer formed by ring-opening addition polymerization of a glycidyl group represented by the following structural formula (III), for example. Here, R represents a divalent organic group, and particularly preferably represents an alkylene group.

Structural formula (III)

The monomer providing the polymer represented by the structural formula (III) may be, for example, a difunctional glycidyl ether monomer having an R structure in the structural formula (III) in its main chain as represented by the following structural formula (IV).

Structural (IV)

Alkyl glycidyl ethers are suitable for use as the glycidyl ether monomer represented by structural formula (IV). Examples thereof include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1, 4-butanediol diglycidyl ether, 1, 5-pentanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1, 6-hexanediol diglycidyl ether.

The glycidyl ether monomer is preferably a low molecular weight glycidyl ether from the viewpoint of easy impregnation into the elastic layer. Further, from the same point of view, an aliphatic glycidyl ether monomer which does not contain any rigid structure in its main chain and thus has a low viscosity is preferable because a monomer having a lower viscosity is more easily impregnated therein. The above specific examples of the alkyl glycidyl ether monomer each satisfy those conditions.

As the solvent, any solvent may be freely selected as long as the solvent satisfies both affinity for the elastic layer and solubility for the glycidyl ether monomer. Examples thereof include: alcohols such as methanol, ethanol, and n-propanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters such as methyl acetate and ethyl acetate. The dipping treatment liquid may be appropriately mixed with a polymerization initiator. Details regarding the polymerization initiator are described later.

The IPN structure of silicone rubber and epoxy resin can be formed by: impregnating the elastic layer with an impregnating solution containing one or more selected glycidyl ether monomers; and polymerizing the monomer.

The polymerization method is not particularly limited, and known methods may be used. Specific examples thereof include methods such as thermal curing and ultraviolet irradiation. In particular, a method comprising curing a glycidyl ether monomer by ultraviolet irradiation is more preferable because the glycidyl ether monomer can be efficiently polymerized and cured in a system without volatilizing outside the system due to excessive heat applied to the monomer.

Known polymerization initiators, such as radical polymerization initiators and ionic polymerization initiators, may be used for the corresponding polymerization process. Specific examples thereof may include the same polymerization initiator as that of the acrylic resin. Among them, a cationic polymerization initiator containing an aromatic sulfonium salt as a main component is preferable. These polymerization initiators may be used alone or in combination.

Further, regarding the blending amount of the polymerization initiator, when the total amount of the compounds (for example, compounds having glycidyl groups) for forming the specific resin is defined as 100 parts by mass, the amount of the polymerization initiator used is preferably 0.5 parts by mass to 10 parts by mass from the viewpoint of efficiently proceeding the formation reaction.

(3) Polyurethane resin

The urethane resin is, for example, a resin having a urethane bond represented by the structural formula (V).

Structure (V)

The presence of a urethane bond can be judged by detecting the presence or absence of a compound derived from the urethane bond by a general mass spectrometry such as pyrolysis GC/MS.

The polyurethane resin is produced by a reaction between an isocyanate compound and a substance having a hydrogen group.

Examples of the isocyanate compound may include 2, 6-Toluene Diisocyanate (TDI), 4 '-diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate (PPDI), 1, 5-Naphthalene Diisocyanate (NDI), and 3, 3-dimethyldiphenyl-4, 4' -diisocyanate (TODI), as well as polymers and modified products of the above isocyanate compounds.

Examples of the substance having a hydrogen group include compounds having a hydroxyl group such as a polyol and moisture in the atmosphere.

As the solvent, any solvent may be freely selected as long as the solvent satisfies both the affinity for the resin layer and the solubility for the isocyanate compound. Examples thereof include: ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters such as methyl acetate and ethyl acetate.

The IPN structure of silicone rubber and polyurethane resin can be formed by: impregnating the elastic layer with an impregnating solution containing one or more selected isocyanate compounds; the layer is heated to react the compound and the substance having a hydrogen group with each other.

In the elastic layer according to the present disclosure, when the fourth sample is sampled from the third region 43 corresponding to the thickness of 10.0 μm to 10.5 μm from the first surface 46 toward the second surface 47 as shown in fig. 4, and when the peak top temperature derived from the dimethylsiloxane structure in the ion thermogram to be measured by the fourth sample is represented by T3 (°c), T1, T2, and T3 preferably satisfy the relationship of the following formula (3) and the following formula (4):

formula (3) T1> T3 is greater than or equal to T2,

formula (4) T1> T3+1.0 (. Degree.C.).

In other words, it is preferable that the first region has an increased hardness as compared with the third region, and the third region has a hardness equal to or higher than that of the second region.

In order to further reduce the stress applied to the toner by the developing roller, the thickness of the high hardness region of the elastic layer is preferably as small as possible. For this reason, the difference (T1-T3) between the peak top temperatures of the first region and the third region is preferably 1.0 (. Degree. C.) or more. That is, the thickness of the high hardness region in the depth direction thereof from the outer surface of the elastic layer can be assumed by the difference (T1-T3) between the peak top temperatures of the first region and the third region. When T1-t3=0 ℃ in the elastic layer formed by the impregnation method satisfying the relationship represented by formula (1), impregnation of any other polymer from the outer surface can reach the third region. In other words, the above fact means that the region from the first surface of the elastic layer to the third region having a depth of 10.5 μm is a high hardness region. Meanwhile, as the difference of "T1-T3" becomes larger, the impregnation of the polymer remains to a greater extent in the immediate vicinity of the outer surface. In order to further reduce the stress applied to the toner, a high hardness region is preferably formed only in the most vicinity of the outer surface. Thus, the difference between "T1-T3" is preferably 0.3℃to 5.9℃and particularly preferably 0.8℃to 5.9℃and more preferably 1.3℃to 5.9 ℃. In addition, in the elastic layer satisfying the relationship represented by the formulas (1) to (4), T1 preferably falls within a range of 468.1 ℃ to 470.8 ℃, and the difference "T1-T2" preferably falls within a range of 3.3 ℃ to 9.1 ℃, more preferably falls within a range of 3.3 ℃ to 6.1 ℃. In addition, in the elastic layer satisfying the formula (2) in addition to the formula (3) and the formula (4), C1 preferably falls within a range of 414.2 ℃ to 423.4 ℃, and the difference of "C1-C2" preferably falls within a range of 0.9 ℃ to 3.6 ℃.

Although the thickness of the elastic layer satisfying the relationship represented by the formulas (1) to (4) is not particularly limited, the thickness is preferably set to 0.1mm to 6.0mm, particularly preferably 0.3mm to 6.0mm, more preferably 1.0mm to 6.0mm, from the viewpoint of achieving both of the relaxation of stress applied to the toner and the prevention of abrasion of the outer surface thereof at a higher level.

[ conductive matrix ]

A conductive mandrel having a cylindrical shape or a cylindrical shape may be used as the conductive base 2. In addition, the conductive elastic layer may be provided on the outer periphery of the mandrel, and in this case, the conductive elastic layer and the mandrel are regarded as a conductive base.

The conductive mandrel has a conductive outer surface, and the surface of the substrate may be subjected to a known surface treatment to improve its adhesion property to an elastic layer provided on its outer periphery. Alternatively, an adhesive layer may be provided thereon. As for the material of the matrix, the matrix may include a conductive material as follows:

metals or alloys, such as aluminum, copper alloys or stainless steel;

chromium plated or nickel plated iron; or alternatively

Synthetic resin having conductivity.

[ elastic layer ]

The elastic layer 1 is a single-layer elastic layer, and forms the outer surface of the electrophotographic member. The reason why silicone rubber is selected as the material of the elastic layer is as follows: even when any other member is abutted against a rubber material used in an electrophotographic member for a long time, the material hardly causes permanent compression deformation in the conductive elastic layer.

Although the thickness of the elastic layer is not particularly limited as described above, the thickness is preferably set to 0.1mm to 6.0mm, particularly preferably 0.3mm to 6.0mm, more preferably 1.0mm to 6.0mm, from the viewpoint of achieving both of the alleviation of stress applied to the toner and the prevention of abrasion of the outer surface thereof at a higher level.

Silicone rubber is classified into two types according to its form. One of them is of the type known as grindable silicone rubber (millable silicone rubber) obtained in the following way: linear polyorganosiloxanes with a high degree of polymerization are used; blending a polyorganosiloxane with a reinforcing filler such as silica to produce a rubber compound; then, a crosslinking agent is added to the compound, and the mixture is heated to cure. Another type is a type of liquid silicone rubber that uses a lower degree of polymerization than the grindable organopolysiloxane. Liquid silicone rubber is further classified into a type of rubber curable in a room and a type of rubber curable by heat. As the silicone polymer used as the main component of the silicone rubber, the following polymers are mainly used each: in the case of a grindable silicone rubber, a polymer having a degree of polymerization of about 4,000 to about 10,000; in the case of liquid silicone rubber, the degree of polymerization is from about 100 to about 2,000.

Further, the elastic layer may be converted into a conductive elastic layer by blending the rubber material with a conductivity imparting agent such as a conductive substance or an ion conductive substance.

Examples of the conductive substance include the following: conductive carbon black such as conductive carbon, carbon for rubber, and carbon for coloring (ink); and metals and metal oxides thereof. Specific examples thereof include: highly conductive carbon such as ketjen black EC and acetylene black; rubber carbons such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; carbon for coloring (ink) obtained by oxidizing carbon black powder; and metals such as copper, silver, and germanium, and metal oxides thereof. Among them, conductive carbon black [ conductive carbon, carbon for rubber, and carbon for coloring (ink) ] is preferable because conductivity can be easily controlled with a small amount of conductive carbon black.

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

In addition, the elastic layer may further contain various additives, for example, plasticizers, fillers, extenders, vulcanizing agents, vulcanizing aids, crosslinking aids, curing inhibitors, antioxidants, processing aids, as needed. Examples of fillers include silica, quartz powder, and calcium carbonate. Those optional components are each blended in an amount within a range that does not inhibit the function of the elastic layer.

< method of Forming >

The method of forming the elastic layer on the outer periphery of the conductive substrate 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 be a method including: first, dies (dies) for holding the mandrel in the mold are fixedly secured to both ends of the cylindrical mold; forming an injection port in the die; then setting the mandrel in the mold; injecting a material for the elastic layer from the injection port; heating the mold after injection at a temperature at which the material solidifies; the cured product was removed from the mold. Examples of the extrusion molding method may be a method including: co-extruding the mandrel and the material for the elastic layer using a cross-head extruder; the material is cured to form a silicone rubber layer at the outer periphery of the mandrel that serves as the main portion of the elastic layer.

When the electrophotographic member is used as a roller member, a polishing step of processing the member into a crown shape (crown shape) may be performed after the formation of the silicone rubber layer on the base body. The term "crown shape" refers to a state formed by polishing a silicone rubber layer at each of both end portions in the length direction of a base body (mandrel) in a large amount so that the thickness of the silicone rubber layer at its central portion is large.

In addition, the polished silicone rubber layer may be pretreated by a surface modification method such as corona treatment, flame treatment or excimer treatment. The performance of the pretreatment may adjust the impregnability in the subsequent impregnation treatment within a desired range.

Thereafter, EB exposure or dipping treatment is performed to increase the hardness of the surface region of the elastic layer. As described in the acrylic monomer, the impregnating solution is diluted with a solvent or the like to an appropriate viscosity and then used. Although the method of impregnating the impregnating treatment liquid into the layer is not particularly limited, dip coating, ring coating, spray coating, or roll coating may be used.

After the dipping treatment, an ultraviolet irradiation treatment or a heat curing treatment is performed to react the respective molecules of the polymer of the second component with each other. In the case of the roller member, the degree of crosslinking in the surface region can be made uniform by irradiating ultraviolet rays while rotating the roller member.

< catalyst Compound >

The catalyst compound is a catalyst for promoting an addition curing reaction between the molecules of the silicone polymer.

Examples of the catalyst compound may include the following:

platinum fine powder; platinum black; chloroplatinic acid; alcohol-modified chloroplatinic acid; olefin complexes of chloroplatinic acid; and complexes of platinum and alkenylsiloxane.

As the catalyst compound, commercially available products may be used, and specific examples thereof include SIP-6829.2, SIP-6832.2, SIP-6830.3, SIP-6831.2, and SIP-6833.2 (each representing the name of a product manufactured by Gelest Inc.).

These compounds may be used alone or in combination.

The content of the catalyst compound in the silicone composition is preferably 1 mass ppm to 100 mass ppm from the viewpoint of curing reactivity.

< other Components >

The composition may contain, in addition to the above-mentioned catalyst compound, various additives such as a reinforcing agent, a curing control agent, a conductive agent, a plasticizer, a vulcanizing agent, a vulcanization aid, a crosslinking aid, an antioxidant, and a processing aid as needed, within a range that does not interfere with the functions of the above-mentioned composition.

[ electrophotographic Process Cartridge and electrophotographic image Forming apparatus ]

The electrophotographic image forming apparatus according to this aspect includes, for example, the following configuration:

an image bearing member capable of bearing an electrostatic latent image;

a charging device capable of charging the image bearing member;

an exposure device capable of forming an electrostatic latent image on the charged image bearing member;

a developing device capable of developing the electrostatic latent image with toner to form a toner image; and

A transfer device capable of transferring the toner image to a transfer material.

Fig. 3 is a schematic cross-sectional view for illustrating an electrophotographic image forming apparatus according to the present aspect.

Fig. 2 is an enlarged sectional view of a process cartridge to be mounted to the electrophotographic image forming apparatus of fig. 3. The processing box is internally provided with: an image bearing member 21 such as a photosensitive drum; a charging device including a charging member 22; a developing device 20 including a developing member 24 and a toner supply member 25 and accommodating toner 201; a cleaning device including a cleaning member 30. Further, the process cartridge is detachably mounted to the main body of the electrophotographic image forming apparatus of fig. 3.

The image bearing member 21 is uniformly charged (primary charging) by a charging member 22 connected to a bias power supply (not shown). The charging potential of the image bearing member 21 at this time is-800V to-400V. Next, exposure light 23 for writing an electrostatic latent image is applied from an exposure device (not shown) to the image bearing member 21 to form an electrostatic latent image on the surface thereof. The LED light and the laser light may each be used as the exposure light 23. The surface potential of the exposed portion of the image bearing member 21 is-200V to-100V.

Next, the toner charged to the negative polarity is applied to the electrostatic latent image (developed) by the developing member 24 to form a toner image on the image bearing member 21. Thus, the electrostatic latent image is converted into a visible image. At this time, a voltage of-500V to-300V is applied to the developing member 24 by a bias power supply (not shown). The developing member 24 is brought into contact with the image bearing member 21 with a nip width of 0.5mm to 3mm therebetween. In the process cartridge of the present embodiment, the toner supply member 25 is brought into rotatable contact with the developing member 24 on the upstream side of the rotation of the developing member 24 with respect to the contact portion between the toner regulating blade 26 serving as the toner regulating member and the developing member 24.

The toner image developed on the image bearing member 21 is primary-transferred onto the intermediate transfer belt 27. The primary transfer member 28 abuts against the rear surface of the intermediate transfer belt 27, and application of a voltage of +100deg.V to +1500V to the primary transfer member 28 causes primary transfer of the toner image having the negative polarity from the image bearing member 21 onto the intermediate transfer belt 27. The primary transfer member 28 may have a roller shape or a blade shape.

When the electrophotographic image forming apparatus is a full-color image forming apparatus, the electrophotographic image forming apparatus performs the above-described respective steps, that is, charging, exposure, development, and primary transfer, for yellow, cyan, magenta, and black. Therefore, in the electrophotographic image forming apparatus shown in fig. 3, a total of four process cartridges each having toner of one of the colors built therein are detachably mounted to the main body of the electrophotographic image forming apparatus. Further, the above-described steps, that is, charging, exposure, development, and primary transfer are sequentially performed with a predetermined time difference therebetween, to establish a state in which four color toner images representing a full-color image are superimposed on the intermediate transfer belt 27.

The toner image on the intermediate transfer belt 27 is conveyed to a position facing the secondary transfer member 29 with rotation of the intermediate transfer belt 27. The recording paper is conveyed to the space between the intermediate transfer belt 27 and the secondary transfer member 29 at a predetermined time along the conveyance path 32 of the recording paper, and the secondary transfer bias applied to the secondary transfer member 29 causes the toner image on the intermediate transfer belt 27 to be transferred onto the recording paper. At this time, the bias to be applied to the secondary transfer member 29 is +1,000v to +4,000v. The recording paper onto which the toner image is transferred by the secondary transfer member 29 is conveyed to the fixing device 31 through a conveying path 32 of the recording paper. In the fixing device 31, the toner image on the recording paper is melted to be fixed to the recording paper, and then the recording paper is discharged to the outside of the electrophotographic image forming apparatus. Thereby, the printing operation is completed.

The toner remaining on the image bearing member 21 without being transferred from the image bearing member 21 onto the intermediate transfer belt 27 is scraped off by the cleaning member 30 for cleaning the surface of the image bearing member 21. Thus, the surface of the image bearing member 21 is cleaned.

According to at least one aspect of the present disclosure, an electrophotographic member can be obtained that can simultaneously achieve both suppression of abrasion of its surface and suppression of toner deterioration at a higher level even when used for formation of an electronic image under a high-temperature and high-humidity environment for a long period of time. According to at least one aspect of the present disclosure, a process cartridge that contributes to stable formation of high-quality electrophotographic images can be obtained. Further, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images can be obtained.

Examples (example)

The present disclosure will be described in more detail by way of specific examples, taking a developing roller as an example. The technical scope of the present disclosure as an electrophotographic member is not limited thereto.

Example 1

[ production of polishing roller ]

A silicone-based PRIMER (product name: PRIMER No.16, manufactured by Shin-Etsu Chemical Co., ltd.) was applied to the surface of a mandrel made of SUS304 having an outer diameter of 6mm and a length of 264mm, and heated at a temperature of 150℃for 20 minutes. Thereby, a conductive base is prepared.

Next, before forming the elastic layer, the materials shown in the following table 1 were mixed and kneaded with a pressure kneader to prepare an addition-curable, grindable, electrically conductive silicone rubber composition.

TABLE 1

Next, the conductive substrate thus prepared and the addition-curable, grindable, conductive silicone rubber composition were integrally sheeted with a cross-head type extrusion molding machine, and heated with a gear oven at 250 ℃ for 20 minutes to cure. After that, the product was further heat-cured with a gear oven at 200℃for 4 hours for secondary curing, and then left at normal temperature for 24 hours.

Next, the elastic layer formed on the outer periphery of the conductive substrate was polished with a cylinder mill to have an outer diameter of 10mm and a protrusion amount of 20 μm. Thereby, a polishing roller was obtained. The term "protrusion amount" refers to a difference between an outer diameter at a position 10mm from each end of the elastic layer and an outer diameter at a center position of the elastic layer, and polishing is performed such that the final protrusion amount becomes 20 μm, or specifically, such that the outer diameter at a position 10mm from each end of the elastic layer becomes 10.000mm, and the outer diameter of the center portion thereof becomes 10.020mm.

The outer diameter was measured at a pitch of 10mm in the length direction of the elastic layer using a laser length measuring machine (product names: CONTROLLER LS-7000 and SENSOR HEAD LS-7030R, manufactured by Keyence Corporation). In addition, the surface roughness of the resulting polished roll was measured with a contact coarser meter surfcore SE3500, manufactured by Kosaka Laboratory ltd.). As a result, the surface roughness Ra was 1.05. Mu.m.

[ pretreatment ]

Next, the polishing roller was subjected to the following treatment as pretreatment. As the ultraviolet lamp used, an excimer ultraviolet lamp (product name: GEL40XTS, manufactured by Harison Toshiba Lighting Corporation) was used, and illuminance of light having a wavelength of 172nm at a position on the surface of the polishing roller was measured using an ultraviolet cumulative light meter (main body: UIT-250, light receiving section: VUV-S172, manufactured by Ushio Inc.). At this time, the distance between the surface and the light meter was adjusted so that the illuminance became 15mW.

The polishing roller was irradiated with ultraviolet light for an accumulated time of 13 seconds so that the accumulated light amount thereof became 200mJ. Thereby, a pretreatment roller was obtained.

[ dipping treatment ]

Subsequently, a dipping treatment is performed. The materials shown in table 2 below as materials of the dipping treatment liquid for the dipping treatment were dissolved and mixed. The pretreatment roller was immersed in the immersion treatment liquid for 5 seconds. Thereby, the immersing treatment liquid is immersed in the roller. Thereafter, the solvent was volatilized by air-drying the roll at normal temperature for 30 minutes, and drying the roll at 90℃for 1 hour.

TABLE 2

Material	Parts by mass
		Difunctional acrylic monomer (product name: EBECRYL 145, manufactured by Daicel-Allnex Ltd.)	5
Photopolymerization initiator (product name: IRGACURE 184, manufactured by BASF SE)	0.25
		Solvent (product name: methyl ethyl ketone, manufactured by Kishida Chemical co., ltd.)	100

Next, in order to react the immersion liquid, the dried roller is irradiated with ultraviolet light from an ultraviolet lamp while rotating. During the ultraviolet treatment, the roller may be rotated by a rotation mechanism. The treatment is carried out as follows: the roller was irradiated with ultraviolet light while rotating at a rotation speed of 20 rpm. A glass plate or the like for preventing contamination of the filter or the ultraviolet lamp may be appropriately disposed between the lamp and the roller. As the ultraviolet lamp used, a high-pressure mercury lamp (manufactured by Eye Graphics co., ltd.) was used. Illuminance of light having a wavelength of 365nm at a position on the roller surface was measured using an ultraviolet accumulated light meter (main body: UIT-250, light receiving portion: UVD-S365, manufactured by Ushio inc.). The output of the lamp and its distance from the surface were adjusted so that the illuminance became 100mW.

By changing the cumulative light quantity thereof to about 15,000mJ/cm ² Ultraviolet light was applied for 200 seconds in the state of (2) to cure the acrylic monomer. Thereby, a developing roller is obtained.

The following evaluation was performed on the resulting developing roller.

[ evaluation method ]

< measurement of T1, T2, T3, C1, and C2 >

First, the areas of the developing roller to be measured were shaved and sliced separately with a microtome to prepare samples. In this regard, as shown in fig. 4, the sample is prepared from 3 regions called a first region 41, a second region 42, and a third region 43. The first region 41 is a region having a thickness of 0.5 μm from the first surface of the elastic layer 44 toward the second surface thereof. The second region 42 is a region corresponding to a thickness of 1.0 μm to 1.5 μm from the second surface toward the first surface. In addition, the third region 43 is a region corresponding to a thickness of 10.0 μm to 10.5 μm from the first surface toward the second surface. A first sample is collected from the first region, a second sample is collected from the second region, a fourth sample is collected from the third region, and their respective total ion thermograms are obtained. The total ion thermogram was measured using the ion trap mass spectrometer described above (product name: polar Q, manufactured by Thermo Electron Corporation). Peak top temperatures T1, T2, and T3 of dimethylsiloxane structures originating from the first region, the second region, and the third region in the ion thermogram are respectively determined from the obtained total ion thermograms. Further, the peak top temperature C1 derived from the acrylic resin in the ion thermogram is determined from the total ion thermogram of the first sample. Further, the peak top temperature C2 derived from the acrylic resin in the ion thermogram was obtained from the total ion thermogram of the third sample obtained by removing the silicone rubber in the first sample by the silicone rubber decomposition method described below. Here, each peak top temperature T1, T2, T3, C1, and C2 is an average value of measurement values of a total of 30 samples obtained as follows: 10 samples were cut out from the center of the developing roller, and 10 samples were cut out from each of the two ends of the developing roller.

A sheet cut out by a microtome (product name: ULTRAMICTOME, manufactured by Leica Microsystems GmbH) was used as a sample of each region.

Specifically, first, a slit is cut from the surface of the developing roller toward the base body with a razor to cut a semi-cylindrical rubber sheet in which a part of the elastic layer is exposed. The rubber sheet was placed in the sample holder of the microtome so that the first surface serving as the outer surface thereof was the upper surface. The first sample was collected from the first region by cutting with a diamond knife, and the fourth sample was collected from the third region by cutting with a diamond knife.

The second sample was collected as follows: the rubber sheet was placed in the sample holder of the microtome so that the second surface of the elastic layer was the upper surface, and then collected from the second area by cutting with a diamond knife.

< method for decomposing Silicone rubber >

For selectively decomposing the siloxane bond of the silicone rubber, a silicone resin-dissolving agent (product name: "eSOLVE 21RS", manufactured by Kaneko Chemical co., ltd.) was used.

The first sample collected with the microtome as described above was immersed in the silicone resin-dissolving agent so that the silicone rubber was dissolved therein. Thereafter, the solution was filtered with a filter to provide a third sample in which the dimethylsiloxane structures derived from the silicone rubber had been removed.

< evaluation of durability >

The developing roller was mounted to a process cartridge of a color laser printer, and the shaving state and the filming state due to abrasion of the surface of the developing roller were evaluated by the color laser printer (product name: color Laser Jet Pro M452dw, manufactured by Hewlett-Packard Company). The evaluation results are shown in table 4 below. The evaluation procedure is as follows.

The cartridge was aged by being left to stand under a high temperature and high humidity environment at a temperature of 30 ℃ and a relative humidity of 95% for 16 hours. Then, in this environment, low-print percentage images having a print percentage of 0.2% are continuously output on the recording paper. The printing operation is performed until the cartridge replacement lamp of the laser printer is lighted. After the lamp is turned on, the image is further printed on another 500 sheets, and then the developing roller is taken out from the process cartridge. Air was blown onto the surface of the roller to remove the surface-coated toner, and the durable developing roller was evaluated according to the following evaluation criteria.

< evaluation criteria >

The outer diameters at positions abutting against the end portions of the squeegees at each of the both end portions of the development roller after durability were measured using a laser length-measuring instrument for outer diameter measurement (product names: CONTROLLER LS-7000 and SENSOR HEAD LS-7030R, manufactured by Keyence Corporation), and the shaving status was evaluated according to the following evaluation criteria.

Grade "a": the change in the outer diameter of the roll after durability is 10 μm or less compared with the outer diameter of the roll before durability.

Grade "B": the change in the outer diameter of the roller after durability is greater than 10 μm and 30 μm or less than the outer diameter of the roller before durability.

Grade "C": the change in the outer diameter of the roller after durability is more than 30 μm compared to the outer diameter of the roller before durability, or cannot be measured due to shaving.

Further, the surface of the development roller after durability was observed with a laser microscope (product name: VK-8700, manufactured by Keyence Corporation) and an objective lens having a magnification of 20. Observations were made at a total of 9 points determined for each sample (i.e., roller) as follows, and the area of adhered toner at each of the 9 points was determined: the toner-coated portion of the surface was divided into 3 portions in the axial direction of the roller, and also into 3 portions in the circumferential direction thereof. An average value of the measured values at 9 points was used as a film formation state, and evaluated according to the following evaluation criteria.

Grade "a": the ratio of the area of the adhered toner to the surface area of the roller is 5% or less.

Grade "B": the ratio of the area of the adhered toner to the surface area of the roller is greater than 5% and 15% or less.

Grade "C": the ratio of the area of the adhered toner to the surface area of the roller is greater than 15%.

The evaluation results are shown in Table 4.

Example 2

A developing roller was produced by the same method as in example 1, except that the ultraviolet irradiation time was changed to 100 seconds, and the roller was evaluated by the same method as in example 1.

Example 3

A developing roller was produced by the same method as in example 2, except that an impregnating treatment liquid for introducing an epoxy-based IPN structure was impregnated in the pretreatment roller in the impregnation treatment. A liquid obtained by dissolving and mixing the following materials was used as the immersion treatment liquid: 5 parts by mass of a glycidyl ether monomer (product name: ethylene glycol diglycidyl ether, manufactured by Tokyo Chemical Industry co., ltd.); 0.1 part by mass of a photopolymerization initiator (product name: "SAN-AID SI-100L", manufactured by Sanshin Chemical Industry co., ltd.); and 100 parts by mass of a solvent (methyl ethyl ketone). The resulting developing roller was evaluated by the same method as in example 1.

Example 4

A developing roller was produced by the same method as in example 2, except that an immersion treatment liquid for introducing an IPN structure based on a polyurethane resin was immersed in the pretreatment roller in the immersion treatment. As the impregnation treatment liquid, a liquid obtained by dissolving and mixing the following materials was used: 14.3 parts by mass of an isocyanate compound (product name: MILLIONATE MR-400, manufactured by Tosoh Corporation); and 100 parts by mass of a solvent (ethyl acetate). The resulting developing roller was evaluated by the same method as in example 1.

Examples 5, 6 and 7

A developing roller was produced by the same method as in example 2, except that the dipping time was changed to 15 seconds, 30 seconds, and 60 seconds, and the roller was evaluated by the same method as in example 1.

Example 8

EB treatment was performed on the polished roller obtained by the same method as in example 1 to produce a developing roller, and the roller was evaluated by the same method as in example 1. In EB processing, an electron beam irradiation apparatus (manufactured by Iwasaki Electric co., ltd.) having a maximum acceleration voltage of 150kV and a maximum electron current of 40mA was used, and nitrogen purging was performed at the time of electron beam irradiation. The treatment was carried out under conditions of an acceleration voltage of 150kV, an electron current of 35mA, a treatment speed of 1m/min, and an oxygen concentration of 100 ppm.

Comparative example 1

1 part by mass of monomethyl trimethoxy silane was mixed as a coupling agent into the composition shown in Table 1 to prepare an addition-curable, grindable, electrically conductive silicone rubber composition. Next, a polishing roller obtained by the same method as in example 1 was used as a developing roller, and the roller was evaluated by the same method as in example 1.

Comparative example 2

A polished roller obtained by the same method as in example 1 was used as a developing roller, and the roller was evaluated by the same method as in example 1.

TABLE 3 Table 3

/>

TABLE 4 Table 4

[ discussion of evaluation results ]

Each of the electrophotographic members of examples 1 to 8 includes a single-layer elastic layer. In each member, since the elastic layer contains silicone rubber and satisfies the condition that T1 > T2, film formation is suppressed.

Further, when examples 1 to 7 and example 8 are compared with each other, in each of the electrophotographic rollers according to examples 1 to 7, the first region contains the polymer not contained in the second region, and the condition of C1> C2 is satisfied. It can be seen that the silicone rubber and the polymer form an IPN structure in a first region from the first surface serving as the outer surface of the elastic layer of each roller to a depth of 0.5 μm. As a result, even when the electrophotographic rollers according to examples 1 to 7 were each used as a developing roller for many electrophotographic image formation under a severe environment of high temperature and high humidity, the evaluation result of abrasion of the outer surface was grade a, and the evaluation result of film formation was also grade a or grade B. From these results, it was found that the electrophotographic rollers according to examples 1 to 7 each had extremely excellent abrasion resistance, and were able to alleviate the pressure applied to the toner.

When examples 1 to 5 and examples 6 and 7 are compared with each other, each of examples 1 to 5 satisfies the condition (T1-T3) > 1.0 (. Degree. C.). Therefore, even when the electrophotographic rollers according to examples 1 to 5 were each used as a developing roller for many electrophotographic image formation under a severe environment of high temperature and high humidity, the evaluation result of the outer surface abrasion of the roller was grade a, and the evaluation result of the film formation was grade a. From these results, it was found that the electrophotographic rollers according to examples 1 to 5 each had extremely excellent abrasion resistance, and were able to further alleviate the stress applied to the toner.

Further, when example 1 and example 2 are compared with each other, the difference "T1 to T3" in example 1 is larger than that in example 2. Therefore, the film formation inhibition effect of the electrophotographic roller according to example 1 was larger than that of the electrophotographic roller according to example 2.

The electrophotographic roller according to comparative example 1 includes an elastic layer formed by using a silicone rubber blended with a silane coupling agent. The elastic layer does not satisfy the condition T1 > T2. Furthermore, it is conceivable that since the silicone rubber is crosslinked in the elastic layer by the silane coupling agent, the hardness of the entire elastic layer increases. As a result, the evaluation grade regarding abrasion resistance was grade a, but the evaluation grade of film formation was grade C.

The electrophotographic roller according to comparative example 2 includes an elastic layer formed by using a silicone rubber not mixed with any silane coupling agent. The elastic layer does not satisfy the relationship of T1 > T2. In addition, the elastic layer is entirely soft. Therefore, the evaluation result of the film formation was grade a, but the evaluation result of the abrasion resistance was grade C.

While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the present disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An electrophotographic member, comprising:

a conductive substrate; and

an elastic layer on the substrate, the elastic layer being composed of a single layer,

the elastic layer comprises a silicone rubber comprising a dimethylsiloxane structure,

characterized in that when a side of the elastic layer facing the substrate is defined as a second surface and a surface of the elastic layer opposite to the second surface is defined as a first surface, and when peak top temperatures derived from dimethylsiloxane structures in an ion thermogram measured from a first sample sampled from a first region where the first surface is 0.5 μm thick toward the second surface are represented by T1, and peak top temperatures derived from dimethylsiloxane structures in an ion thermogram measured from a second sample corresponding to a second region where the second surface is 1.0 μm to 1.5 μm thick toward the first surface of the elastic layer are represented by T2, and both units of T1 and T2 are in the temperature range, the T1 and T2 satisfy a relationship represented by the following formula (1):

formula (1) T1> T2.

2. The electrophotographic member according to claim 1, wherein the difference "T1-T2" between the T1 and the T2 falls in the range of 3.3 ℃ to 9.1 ℃.

3. The electrophotographic member according to claim 1 or 2,

wherein the first sample comprises a polymer not comprised by the second sample, and

wherein when a peak top temperature of the ion spectrum measured by the first sample derived from the polymer is represented by C1 and a peak top temperature of the ion spectrum measured by a third sample obtained by decomposing the silicone rubber in the first sample derived from the polymer is represented by C2, and units of the C1 and the C2 are both at C, the C1 and the C2 satisfy a relationship represented by the following formula (2):

formula (2) C1> C2.

4. An electrophotographic member according to claim 3, wherein the difference "C1-C2" between the C1 and the C2 falls in the range of 0.9 ℃ to 3.6 ℃.

5. An electrophotographic member according to claim 3, wherein the polymer is selected from the group consisting of (meth) acrylic resins; an epoxy resin; and at least one of the group consisting of polyurethane resins.

6. The electrophotographic member according to claim 1 or 2, wherein when a peak top temperature derived from a dimethylsiloxane structure in an ion thermogram measured from a fourth sample corresponding to a third region having a thickness of 10.0 μm to 10.5 μm from the first surface toward the second surface of the elastic layer is represented by T3, and a unit of the T3 is °c, the T1, the T2, and the T3 satisfy a relationship represented by the following formula (3):

The formula (3) T1> T3 is more than or equal to T2.

7. The electrophotographic member according to claim 6, wherein the difference "T1-T3" between the T1 and the T3 falls within a range of 0.3 ℃ to 5.9 ℃.

8. The electrophotographic member according to claim 6, wherein the T1 and the T3 satisfy a relationship represented by the following formula (4):

formula (4) T1> t3+1.0.

9. The electrophotographic member according to claim 8, wherein the difference "T1-T3" between the T1 and the T3 is 1.3 ℃ to 5.9 ℃.

10. The electrophotographic member according to claim 1 or 2, wherein the thickness of the elastic layer is 0.1mm to 6.0mm.

11. An electrophotographic member as in claim 1 or 2, wherein the electrophotographic member is a developing roller.

12. An electrophotographic process cartridge detachably mountable to a main body of an electrophotographic image forming apparatus, wherein said electrophotographic process cartridge comprises the electrophotographic member according to any one of claims 1 to 11.

13. An electrophotographic process cartridge according to claim 12, wherein said electrophotographic process cartridge further comprises a developing device that houses toner, and includes said electrophotographic member as a developing roller.

14. An image forming apparatus, comprising:

an image bearing member capable of bearing an electrostatic latent image;

a charging device capable of charging the image bearing member;

a developing member capable of developing the electrostatic latent image with toner to form a toner image; and

a transfer device capable of transferring the toner image onto a transfer material,

characterized in that the developing member is an electrophotographic member according to any one of claims 1 to 11.