Electrophotographic member and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic member that reduces a frictional force on a surface and improves toner releasability while maintaining medium followability, and is excellent in the density uniformity of images.SOLUTION: An electrophotographic member has a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer. The surface layer includes a silicone graft urethane resin. The electrophotographic member has an elastic deformation power ηIT of 30-90%, which is calculated from a load variation curve obtained by bringing a Vickers indenter into contact with an outer surface of the surface layer and conducting a nano indentation test based on ISO 14577 with a test load of 260 μN, and has a Martens hardness of 12-200 N / mm2, which obtained by conducting the nano indentation test on the outer surface of the surface layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electrophotographic member used in an electrophotographic image forming apparatus such as a copying machine or a printer, and to an electrophotographic image forming apparatus. [Background technology]

[0002] Electrophotographic image forming devices (hereinafter also referred to as "image forming devices") widely use a tandem method in which toner images of each color (yellow (Y), magenta (M), cyan (C), and black (K)) are superimposed on an intermediate transfer belt, and then transferred all at once onto paper to obtain a full-color image.

[0003] In order to achieve even higher image quality in such image forming devices, an intermediate transfer belt having an elastic layer in at least one layer of its layer structure (hereinafter referred to as an elastic intermediate transfer belt) may be adopted instead of an intermediate transfer belt using a resin. Because the elastic intermediate transfer belt has a flexible elastic layer, it can reduce the pressure acting on the toner in the transfer section, which is effective in preventing the so-called "hollow toner phenomenon." Furthermore, because the elastic intermediate transfer belt has good adhesion to the paper in the secondary transfer section, it not only improves the transfer efficiency for general paper, but also has an effect on the transferability for cardboard and paper with unevenness.

[0004] The material forming the surface of the elastic intermediate transfer belt is preferably one that is harder than the elastic layer, but not so hard that it wears off or peels off due to friction with various contact members. However, using a material that is too hard can impair the media tracking ability, which is an advantage of the elastic belt, so a material that is more flexible is used as long as it does not wear off or peel off. In addition to reducing frictional force to improve wear resistance, reducing surface free energy is also required to improve toner releasability. For example, Patent Document 1 discloses the use of a silicone-grafted urethane resin, which provides high flexibility and low friction, as the surface layer material of a developing roller. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-086171 Summary of the Invention [Problem to be solved by the invention]

[0006] When a low-hardness urethane resin is used as the surface layer of an elastic intermediate transfer belt, it has excellent media followability, but there are problems in that it is difficult to separate from various contact members and the release property of toner that follows the media is reduced. Furthermore, when a urethane resin with excellent flexibility is used for the surface layer of an elastic intermediate transfer belt, the frictional force is high, which poses a problem in terms of abrasion resistance. Furthermore, when a material such as that described in Patent Document 1 is used for the surface layer of an elastic intermediate transfer belt, there are problems in that the toner releasability is low, which leads to poor uniformity in image density.

[0007] Therefore, the present disclosure is directed to an electrophotographic member that reduces surface friction, improves toner releasability while maintaining media tracking, and provides excellent image density uniformity, and further to an electrophotographic image forming apparatus that includes the electrophotographic member as an intermediate transfer belt. [Means for solving the problem]

[0008] The present disclosure provides an electrophotographic member having a base layer, a resilient layer on the base layer, and a surface layer on the resilient layer, the surface layer comprises a silicone-grafted urethane resin, The elastic deformation power ηIT calculated from a load-displacement curve obtained by a nanoindentation test based on ISO 14577 in which a Vickers indenter is brought into contact with the outer surface of the surface layer and a test load of 260 μN is set to be 30 to 90%, and The Martens hardness of the outer surface of the surface layer determined by the nanoindentation test is 12 to 200 N / mm2 The present invention relates to an electrophotographic member,

[0009] The present disclosure also relates to an electrophotographic image forming apparatus equipped with the electrophotographic member. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide an electrophotographic member that reduces surface friction, improves toner releasability while maintaining media tracking, and has excellent image density uniformity. Also, according to the present disclosure, it is possible to provide an electrophotographic image forming apparatus that includes the electrophotographic member as an intermediate transfer belt. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing an example of an image forming apparatus using an elastic intermediate transfer belt. [Figure 2] FIG. 2 is a cross-sectional view showing the layer structure of an elastic intermediate transfer belt. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the upper and lower limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0013] Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to the following description. The present disclosure provides an electrophotographic member having a base layer, a resilient layer on the base layer, and a surface layer on the resilient layer, the surface layer comprises a silicone-grafted urethane resin, The elastic deformation power ηIT calculated from a load-displacement curve obtained by a nanoindentation test based on ISO 14577 in which a Vickers indenter is brought into contact with the outer surface of the surface layer and a test load of 260 μN is set to be 30 to 90%, and The Martens hardness of the outer surface of the surface layer determined by the nanoindentation test is 12 to 200 N / mm 2 The present invention relates to an electrophotographic member,

[0014] The inventors speculate as follows why the above characteristics enable the effects of the present disclosure to be realized. If the media conformability or toner release property is low, the toner will not be sufficiently transferred to the media, and density uniformity will be impaired. It is believed that toner release property will be reduced if the surface free energy of the outer surface of the surface layer is high and the intermolecular force between the surface layer and the toner is strong, or if the Martens hardness or elastic deformation power of the outer surface of the surface layer is low and the contact area with the toner is large. If the surface layer is made solely of urethane resin, it will have good media conformability due to its excellent flexibility, but its high surface free energy will reduce toner release property and impair density uniformity.

[0015] Furthermore, even when the surface free energy is low, if the Martens hardness or elastic deformation power ηIT of the surface layer is low, the contact area between the surface layer and the toner increases. As a result, the toner release property decreases and the density uniformity is impaired. Therefore, in order to improve the density uniformity, it is considered necessary to reduce the surface free energy without impairing the media followability and increase the Martens hardness or elastic deformation power of the surface layer to improve the toner release property.

[0016] In the electrophotographic member of the present disclosure, the surface layer contains a silicone-grafted urethane resin. The silicone-grafted urethane resin has, for example, a structure in which a silicone structure is grafted to a urethane resin. Because the main chain is a urethane resin, it has excellent flexibility, improving media tracking. Furthermore, the silicone structure bonds to the urethane resin main chain and extends to the side chains to form a graft shape, reducing surface free energy and improving toner release properties. This is thought to improve density uniformity. Furthermore, the silicone structure extending to the side chains also reduces frictional force.

[0017] The elastic deformation power ηIT calculated from the load-displacement curve obtained by a nanoindentation test based on ISO 14577, in which a Vickers indenter is placed on the outer surface of the surface layer and a test load of 260 μN is 30 to 90%. In the nanoindentation test, the test load is 260 μN, which may correspond to the load applied when toner is pressed into an intermediate transfer belt in an electrophotographic image forming apparatus. In nanoindentation measurements, a certain level of elastic deformation power or higher indicates that the surface layer maintains its elasticity and easily returns to its original shape when the load is removed. With the elastic deformation power ηIT within the above range, the deformed surface layer returns to its original state without permanent deformation, thereby reducing the contact area between the toner and the surface layer. This is believed to improve toner releasability and density uniformity. The elastic deformation power ηIT is preferably 40 to 85%.

[0018] The Martens hardness of the outer surface of the surface layer determined by the nanoindentation test is 12 to 200 N / mm 2 The Martens hardness indicates the amount of deformation when a load is applied. In other words, the higher the Martens hardness, the smaller the amount of deformation when a load is applied. Therefore, by keeping the Martens hardness within the above range, the contact area between the toner and the surface layer is reduced. This is thought to improve toner releasability and density uniformity. The Martens hardness is preferably 15 to 175 N / mm 2 is.

[0019] To control the elastic deformation power ηIT within the above range, for example, the number-average molecular weight of the polyol may be increased. The elastic deformation power ηIT can be increased by using a polyol with a large number-average molecular weight. The elastic deformation power ηIT can also be decreased by using a polyol with a small number-average molecular weight.

[0020] To control the Martens hardness within the above range, for example, the number-average molecular weight of the polyol may be increased or the type of isocyanate may be changed. The Martens hardness can be increased by using a polyol with a small number-average molecular weight or a biuret or nurate isocyanate. The Martens hardness can also be decreased by using a polyol with a large number-average molecular weight or an adduct isocyanate.

[0021] As explained by the above mechanism, by using silicone-grafted urethane resin and satisfying both the elastic deformation power ηIT and Martens hardness, it is thought that they exert a synergistic effect, making it possible to achieve the effects of reduced friction, media tracking, and uniform image density.

[0022] Furthermore, the amount of silicon element on the outer surface of the surface layer, as detected by XPS (X-ray photoelectron spectroscopy), is preferably 10 to 25 atomic % (atomic number %), and more preferably 10 to 21 atomic %, based on the total of Si, N, C, and O. When the amount of silicon element is within the above range, silicone structures are appropriately arranged on the outer surface of the surface layer, thereby reducing friction and further improving wear resistance.

[0023] Furthermore, it is preferable that the silicone-grafted urethane resin has, in the molecule, at least one selected from the group consisting of a structure represented by the following formula (2-1), a structure represented by the formula (2-2), and a structure represented by the formula (2-3), and a structure represented by the following formula (1): [ka] In formula (1), R 1 ~R 3 are each independently a linear or branched alkylene group having 1 to 12 carbon atoms (preferably 3 to 8 carbon atoms). [ka]

[0024] In formulas (2-1) to (2-3), X 21 ~X 23 each independently represents a linear or branched alkylene group having 1 to 12 carbon atoms (preferably 2 to 8 carbon atoms). These structures can be confirmed by analyzing the surface layer by pyrolysis gas chromatography mass spectrometry (pyrolysis GC-MS).

[0025] When the silicone-grafted urethane resin has the structure represented by formula (1), the Martens hardness of the surface layer increases, and toner releasability is further improved. The structure represented by formula (1) can be introduced into the silicone-grafted urethane resin by using, for example, biuret polyisocyanate as a material for the urethane resin.

[0026] Furthermore, when the silicone-grafted urethane resin has at least one of the structures represented by formulas (2-1) to (2-3), it has excellent flexibility and media followability is further improved. This is thought to further improve density uniformity. Note that the structure represented by formula (2-1) can be obtained by using, for example, polyether polyol as a material for the urethane resin, without using silicone grafted urethane. The structure represented by formula (2-2) can be introduced into a silicone-grafted urethane resin by using, for example, a polyester polyol as a material for the urethane resin. The structure represented by formula (2-3) can be introduced into a silicone-grafted urethane resin by using, for example, a polycarbonate polyol as a material for the urethane resin.

[0027] The silicone-grafted urethane resin preferably contains 5.0 to 65.0 mass %, more preferably 25.0 to 45.0 mass %, of at least one selected from the group consisting of a structure represented by formula (2-1), a structure represented by formula (2-2), and a structure represented by formula (2-3). The silicone-grafted urethane resin preferably contains 35.0 to 95.0 mass %, and more preferably 55.0 to 75.0 mass %, of the structure represented by formula (1).

[0028] The silicone-grafted urethane resin preferably has a structure represented by the following formula (3) in the molecule: The structure represented by formula (3) corresponds to the structure represented by formula (2-1) above. [ka]

[0029] In formula (3), Z represents either a hydrogen atom or a methyl group, and m represents an integer of 3 to 30, preferably 3 to 9. Formula (3) contains an ether bond in the molecule and has excellent flexibility, which can further improve media tracking ability. In particular, in formula (3), it is more preferable that Z is a hydrogen atom and m is an integer of 5 to 7. It is believed that this range improves toner releasability and density uniformity. The structure represented by formula (3) can be introduced into a silicone-grafted urethane resin by using, for example, polyethylene glycol or polypropylene glycol as a material for the urethane resin. Polyethylene glycol is preferred.

[0030] The silicone-grafted urethane resin preferably has a structure represented by formula (4), a structure represented by formula (5), and a structure represented by formula (6) in the molecule. [ka]

[0031] In formula (4), R 41 ~R43 each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms). The structure represented by formula (4) can be introduced into a silicone-grafted urethane resin, for example, by using a one-end-modified silicone oil as a material for the urethane resin.

[0032] In formula (5), R 51 , R 52 each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms, more preferably 1 carbon atom). The structure represented by formula (5) can be introduced into a silicone-grafted urethane resin, for example, by using silicone oil as a material for the urethane resin.

[0033] In formula (6), R 61 represents a trivalent hydrocarbon group having 1 to 12 carbon atoms (preferably 3 to 9 carbon atoms). The structure represented by formula (6) can be introduced into a silicone-grafted urethane resin, for example, by using a silicone oil modified with a diol at one end as a material for the urethane resin. The silicone-grafted urethane resin more preferably has a structure in which a diol-modified silicone oil is grafted at one end.

[0034] These structures can be confirmed by analyzing the surface layer using pyrolysis gas chromatography mass spectrometry (pyrolysis GC-MS). It is believed that when the silicone-grafted urethane resin has the structure of formulas (4) to (6), the abrasion resistance and toner releasability are improved, and the density uniformity is improved.

[0035] The total content of the structure represented by formula (4), the structure represented by formula (5), and the structure represented by formula (6) in the silicone-grafted urethane resin is preferably 0.02 to 0.35 mass%, more preferably 0.10 to 0.25 mass%.

[0036] The hexadecane contact angle of the outer surface of the surface layer is defined as A1, and the hexadecane contact angle after wiping the outer surface of the surface layer 50 times with hexane-soaked Bemcot paper at a force of 5 N is defined as A2. In this case, A2 / A1 is preferably 0.90 to 1.20, and more preferably 0.95 to 1.05.

[0037] When the surface layer is covered with unreacted terminal-modified silicone oil, wiping with Bemcot paper soaked in hexane removes the oil that has seeped out to the surface, revealing the graft structure that was previously covered, and the contact angle increases. On the other hand, when the amount of terminal-modified silicone oil added is small, the graft structure is damaged by friction during wiping, and the contact angle decreases. Therefore, by keeping A2 / A1 within the above range, the graft structure is not damaged during image formation, and toner releasability can be stabilized.

[0038] A2 / A1 can be increased by increasing the amount of terminally modified silicone oil added relative to the polyol, and A2 / A1 can be decreased by decreasing the amount of terminally modified silicone oil added relative to the polyol.

[0039] Next, the configuration of the electrophotographic member will be described. Furthermore, the configuration of each of the electrophotographic member will be described, and a manufacturing method thereof will also be described. However, the present disclosure is not limited to the following description.

[0040] The electrophotographic member is a laminate composed of at least three layers, namely, a base layer 21, an elastic layer 22, and a surface layer 23, as illustrated in FIG. 2. However, it is not limited to these three layers, and a primer layer for improving adhesion between the layers or an intermediate layer for suppressing bleeding from the elastic layer 22 may be added. The electrophotographic member may have an endless belt shape. For example, the surface layer constitutes the outer surface of the electrophotographic member. The electrophotographic member is preferably an intermediate transfer member.

[0041] (base layer) The base layer 21 will now be described. The base layer 21 is, for example, a cylindrical, seamless layer in the form of a roll or belt. Suitable materials for the base layer 21 include, for example, resin materials such as polyether ether ketone, polyethylene terephthalate, polybutylene naphthalate, polyester, polyimide, polyamide, polyamideimide, polyacetal, polyphenylene sulfide, and polyvinylidene fluoride. The base layer preferably contains polyimide.

[0042] The resin for the base layer 21 may be made conductive by adding a conductive compound such as metal powder, conductive oxide powder, conductive carbon, lithium salt, or ionic liquid. From the viewpoints of productivity and conductivity, for example, polyvinylidene fluoride to which polyalkylene glycol and lithium salt have been added may be used for the base layer 21. Combinations of other resins and conductive agents listed above may also be used.

[0043] The thickness of the base layer 21 is preferably 10 to 500 μm, more preferably 50 to 200 μm. If it is 10 μm or more, it is preferable from the viewpoint of mechanical strength. If it is 500 μm or less, suitable rigidity can be obtained.

[0044] (elastic layer) The elastic layer 22 will now be described. The elastic layer 22 needs to have a suitable degree of flexibility in order to conform to the surface shape of the recording medium. Examples of such flexible materials include rubber materials and elastomer materials such as silicone rubber, urethane rubber, chloroprene rubber, acrylic rubber, olefin elastomer, styrene elastomer, polyamide elastomer, polyester elastomer, and urethane resin elastomer.

[0045] The elastic layer 22 preferably contains silicone rubber. The elastic layer 22 may be a cured product of an addition-curing liquid silicone rubber mixture. The hardness of the silicone rubber can be controlled by its crosslink density, and the crosslink density can be reduced to lower the hardness to impart greater flexibility. Furthermore, among the materials listed above, silicone rubber has the highest shape stability, and can maintain a stable shape even during transportation or when placed under pressure for long periods of time. By including silicone rubber in the elastic layer 22, good media conformability can be achieved, improving image density uniformity.

[0046] The elastic layer 22 may be made conductive by adding a conductive compound such as metal powder, conductive oxide powder, conductive carbon, lithium salt, or ionic liquid. For example, a conductive agent may be added to an addition-curing liquid silicone rubber mixture. For example, silicone rubber with a small compression set (JISK 6262) is preferred even in the low hardness range. In addition to silicone rubber, other resins and conductive agents listed above may also be used.

[0047] The thickness of the elastic layer 22 is preferably 100 μm to 1000 μm, more preferably 200 μm to 450 μm, and even more preferably 200 μm to 300 μm. The hardness of the elastic layer 22 measured using a micro rubber hardness tester (MD-1 Type C, manufactured by Kobunshi Keiki Co., Ltd., temperature 23° C., relative humidity 40%) is preferably 85° or less.

[0048] From the viewpoint of mechanical strength, the conductive agent compounding ratio for the elastic layer 22 is preferably 10 parts by weight or less per 100 parts by weight of silicone rubber, which provides the elastic layer 22 with stable conductivity suitable for an intermediate transfer belt.

[0049] The elastic layer 22 may also contain other additives such as fillers, crosslinking agents (crosslinking accelerators, crosslinking retarders, crosslinking aids), scorch inhibitors, antiaging agents, softeners, heat stabilizers, flame retardants, flame retardant aids, ultraviolet absorbers, and rust inhibitors. As the crosslinking agent, a silicone polymer having silicon-bonded active hydrogen groups only in the side chains is preferred. For example, the elastic layer 22 is a cured product of an addition-curing liquid silicone rubber mixture containing a conductive agent, a hydrosilylation catalyst, and a crosslinking agent.

[0050] The intermediate transfer belt is required to be flame retardant because it is electrically conductive at the transfer section. The elastic layer 22 may contain a flame retardant. Examples of flame retardants include metal hydroxides such as magnesium hydroxide and aluminum hydroxide that utilize endothermic properties, platinum compounds and phenolic compounds that suppress thermal decomposition, intumescent compounds that have an oxygen blocking effect, and phosphate ester condensation compounds. The elastic layer 22 may also contain a reinforcing filler such as fumed silica, crystalline silica, wet silica, fumed titanium oxide, or cellulose nanofiber.

[0051] The method for producing the elastic layer is not particularly limited. For example, a layer of an addition-curing liquid silicone rubber mixture is formed on the outer surface of a substrate by a known method, and the liquid silicone rubber in the layer is cured. The curing method can be, for example, a heating method. The heating conditions can be appropriately set depending on the silicone rubber material used and are not particularly limited, but examples include 100 to 250°C and 0.5 to 300 minutes. Heating can be performed in multiple stages at different temperatures.

[0052] Furthermore, a primer layer may be provided between the base layer 21 and the elastic layer 22 to improve adhesion, if necessary. The thickness of the primer layer is preferably 0.1 μm or more and 3 μm or less from the viewpoint of reducing cohesive failure within the primer layer. In order to improve the adhesiveness of the surface layer, the surface of the elastic layer may be surface treated by a known method such as excimer UV.

[0053] (Surface layer) Next, the surface layer 23 will be described. The surface layer preferably has excellent flexibility, resulting in excellent media tracking, and low surface free energy and low friction to improve toner release. Urethane resins, which are flexible, highly flex-resistant, and crack-resistant, are examples of such surface layers, but their high surface free energy and friction are a problem. Therefore, by mixing a modified resin, such as a silicone resin or an acrylic resin, with the urethane resin, it is possible to form a urethane resin surface layer with low surface free energy and low friction. In the present disclosure, the surface layer contains a silicone-grafted urethane resin. For example, a silicone-grafted urethane resin may be used, in which a structure containing silicon and an organic group derived from a silicone oil, such as a diol-modified silicone oil at one end, is introduced as a side chain into the urethane resin main chain.

[0054] (Formation of urethane resin) The urethane resin contains a urethane bond formed by the reaction of the terminal hydroxyl group of the polyol and the terminal isocyanate group of the isocyanate. Polyol is a general term for polyhydric alcohols having multiple hydroxyl groups, and examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, and linear glycols. It is preferable to use at least one selected from the group consisting of the above polyols.

[0055] Polyester polyol is a general term for polyols having two or more ester bonds and two or more hydroxy groups in the molecule, and is obtained by the condensation reaction of a carboxylic acid such as adipic acid or sebacic acid with a polyhydric alcohol. Examples of polyester polyols include, but are not limited to, Nipporan 1004 manufactured by Tosoh Corporation and Kuraray Polyol P-510, P-2010, and P-5010 manufactured by Kuraray Co., Ltd.

[0056] Polyether polyol is a general term for polyols containing two or more ether bonds and two or more hydroxyl groups in the molecule, and is obtained by addition polymerization of ethylene oxide or propylene oxide. Polyether polyols include, but are not limited to, polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMEG).

[0057] Polycarbonate polyol is a general term for polyols that have two or more carbonate bonds and two or more hydroxyl groups in the molecule, and is obtained by transesterification of an alkanediol such as 1,6-hexanediol with a carbonate diester. Examples of polycarbonate polyols include, but are not limited to, Nipporan 981 manufactured by Tosoh Corporation, Duranol T5652 manufactured by Asahi Kasei Corporation, and Kuraray Polyol C-2090 manufactured by Kuraray Co., Ltd.

[0058] In addition to the above polyols, acrylic polyols, epoxy polyols, polyolefin polyols, unreactive silicone group-containing polyols, and flame-retardant polyols having a phosphorus structure may also be used. Preferred examples include linear glycols having 2 to 8 carbon atoms, such as 1,4-butanediol. In addition to the difunctional polyol, a trifunctional castor oil-derived polyol, a tetrafunctional pentaerythritol, etc. may also be used.

[0059] The number average molecular weight of the polyol is preferably from 60 to 1,500, more preferably from 190 to 400, and particularly preferably from 285 to 315. The hydroxyl value mgKOH / g of the polyol is preferably from 110 to 1,900, more preferably from 280 to 590, and particularly preferably from 350 to 400.

[0060] Isocyanate is a general term for compounds that have multiple isocyanate groups (-NCO) within the molecule, and includes aliphatic isocyanates, aromatic isocyanates, and their derivatives. Aliphatic isocyanates include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI). Aliphatic isocyanates include hexamethylene diisocyanate (HDI).

[0061] The isocyanate used in the surface layer 23 may be, for example, a polyisocyanate having an HDI skeleton. The isocyanate is preferably at least one selected from the group consisting of biuret polyisocyanate, adduct polyisocyanate, and nurate polyisocyanate. The adduct type polyisocyanate is not particularly limited, but examples thereof include Duranate E402-B80B (manufactured by Asahi Kasei Corporation), etc. The nurate type polyisocyanate is not particularly limited, but examples thereof include Duranate TPA-B80E (manufactured by Asahi Kasei Corporation).

[0062] In particular, for the surface layer of an intermediate transfer belt having an elastic layer, from the viewpoints of media tracking ability and toner releasability, it is preferable to use a biuret polyisocyanate represented by the following formula (7): As the biuret polyisocyanate, a commercially available product may be used, for example, Duranate SBB-70P (manufactured by Asahi Kasei Corporation).

[0063] [ka]

[0064] In the above formula (7), R 71 ~R 73 Each of the groups represents a linear or branched alkylene group having 1 to 12 carbon atoms. Formula (7) can have a structure represented by formula (1) in a silicone-grafted urethane resin.

[0065] Regarding polyisocyanate, from the viewpoint of adjusting the reaction rate and the storage stability of the surface layer coating solution, it is preferable to use a blocked polyisocyanate in which the terminal isocyanate group is blocked with a blocking agent such as methyl ethyl ketoxime (MEKO) or 3,5-dimethylpyrazole (DMP). Examples of blocked polyisocyanate include Duranate SBB-70P, E402-B80B, and TPA-B80E manufactured by Asahi Kasei Corporation. The present invention is not limited to the above.

[0066] The urethane resin material of the surface layer 23 may also contain additives such as a chain extender and a crosslinking agent. Examples of chain extenders and crosslinking agents include glycols such as ethylene glycol and 1,4-butanediol, hexanetriol, trimethylolpropane, and amines, but the present invention is not limited to these.

[0067] The mixing ratio of the polyol and polyisocyanate in a mixture is usually such that the molar ratio (NCO / OH) of the hydroxyl groups (OH) contained in the polyol to the isocyanate groups (NCO) contained in the polyisocyanate is preferably 0.8 to 1.5, more preferably 0.9 to 1.2.

[0068] (Formation of silicone-grafted urethane resin) One way to impart low friction and low surface energy properties to urethane resin is to form a silicone-urethane copolymer containing a silicone-derived structure within the urethane resin. Types of silicone-urethane copolymers include random copolymers, alternating copolymers, block copolymers, and graft copolymers. In this disclosure, a silicone-grafted urethane resin is used. Graft copolymers with a main chain of urethane rubber and a side chain containing silicon and organic groups derived from modified silicone oil are particularly preferred.

[0069] Silicone-grafted urethane resin can be formed by mixing polyol and polyisocyanate, which are urethane resin materials, with a single-end-modified silicone oil such as a single-end diol-modified silicone oil in a certain ratio and heating the mixture. That is, the silicone-grafted urethane resin is preferably a cured product of a composition containing polyol, polyisocyanate, and single-end-modified silicone oil. The single-end modification is preferably by modification with a hydroxy group. The hydroxy group of the single-end-modified silicone oil and the terminal isocyanate of the polyisocyanate bond to form a silicone-grafted urethane resin in which a silicone structure has been introduced into the urethane resin. The composition may contain a catalyst, a solvent, and the like, as needed.

[0070] The one-terminal-modified silicone oil is preferably at least one selected from the group consisting of one-terminal-diol-modified silicone oil and one-terminal-carbinol-modified silicone oil. An example of the one-terminal-carbinol-modified silicone oil is X-22-170DX (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0071] The one-terminal diol-modified silicone oil is preferably one represented by the following formula (8). [ka]

[0072] In the structural formula (8), n is an integer of 0 to 100, and R 81 , R 85 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, and R 82 ~R 84 each independently represents a linear or branched alkylene group having from 1 to 6 carbon atoms. In addition, in the above formula (8), X represents an oxygen atom, a sulfur atom, or a single bond.

[0073] The number average molecular weight of the one-terminal diol-modified silicone oil represented by the above formula (8) is preferably 1,000 or more and 15,000 or less. The hydroxyl value mgKOH / g of the one-terminal diol-modified silicone oil represented by the above formula (8) is preferably 8 or more and 115 or less. Examples of the one-terminal diol-modified silicone oil include, but are not limited to, X-22-176DX and X-22-176F manufactured by Shin-Etsu Chemical Co., Ltd., and Silaplane series FM-DA11 and FM-DA21 manufactured by JNC Corporation.

[0074] One method for forming the surface layer 23 containing urethane rubber is to spray or dip-coat a coating liquid of a surface layer resin composition containing the above-mentioned silicone-grafted urethane resin material, and then cure it by heating or by irradiating it with light such as ultraviolet light. Taking into consideration the compatibility with each material, the coating liquid of the surface layer resin composition can be made by adding alcohols such as methanol and ethanol, aromatic hydrocarbon solvents such as xylene and toluene, ester solvents such as ethyl acetate and butyl acetate, or volatile solvents such as 2-butanone.

[0075] The thickness of the surface layer 23 is preferably 3 to 15 μm, and more preferably 5 to 10 μm, from the viewpoint of not impairing the flexibility of the elastic layer. The outer peripheral surface of the elastic layer 22 may be surface-treated to improve the adhesion between the elastic layer 22 and the surface layer 23. Examples of the surface treatment method include corona discharge and excimer UV irradiation.

[0076] (Measurement of Martens hardness and elastic deformation power ηIT using nanoindentation method) The Martens hardness and elastic deformation power η IT of the outer surface of the surface layer can be specifically evaluated by the following method. The electrophotographic member is cut into a sheet measuring 20 mm in length and 20 mm in width, and the Martens hardness and elastic deformation power ηIT can be measured by nanoindentation. Using a commercially available device conforming to ISO 14577, the Martens hardness and elastic deformation power ηIT can be calculated from the obtained load-displacement curve according to the indentation test procedure specified in ISO 14577. In this disclosure, a nanoindenter device conforming to the above ISO standard (PICODENTOR HM500 manufactured by FISCHER) is used. Measurement environment: 23°C, relative humidity 40% Indenter: Vickers indenter Measurement load: 260μN ·Number of measurement points: 3 points average

[0077] (Measurement of silicon element amount on outer surface by XPS) The amount of elemental silicon on the outer surface of the surface layer can be measured using X-ray photoelectron spectroscopy (XPS) as follows: The surface layer is cut into a piece measuring 5 mm in length and 5 mm in width, and the piece is attached to a sample stage with carbon tape with the outer surface facing up, and the outer surface is analyzed using an XPS device. The amount of elemental silicon can be measured from the detected peak intensity of elemental silicon. In the present disclosure, the measurement is performed using the following XPS device and measurement conditions. Equipment used: ULVAC-PHI PHI5000VersaProbe II Irradiation: Al-Kα radiation Beam diameter: 100 μm Output: 25W 15kV Photoelectron capture angle: 45° Pass Energy: 58.70 eV Step size: 0.125 eV XPS peaks: Si2p, N1s, C1s, O1s Measurement range: 300 μm x 200 μm

[0078] (Change in hexadecane contact angle A2 / A1 on the outer surface of the surface layer) The change in hexadecane contact angle was introduced as an indicator of whether the graft structure of the surface layer was damaged during image formation. The hexadecane contact angle of the outer surface of the surface layer was defined as A1, and the hexadecane contact angle after wiping the surface layer 50 times with hexane-soaked Bemcott paper at a force of 5 N was defined as A2. The contact angle change rate was then defined as A2 / A1. For example, an A2 / A1 ratio of approximately 1.0 indicates that the graft structure of the surface layer 23 was not damaged during image formation, while a ratio below 1.0 indicates that the graft structure was damaged. Furthermore, increasing the amount of mono-terminally diol-modified silicone oil added increases the contact angle immediately after wiping with hexane, resulting in an A2 / A1 ratio greater than 1.0. This is believed to be due to the fact that unreacted silicone oil floats to the outer surface, covering the graft structure, and that wiping the surface layer with hexane removes the unreacted silicone oil, revealing the graft structure.

[0079] A2 / A1 can be specifically evaluated by the following method. The obtained intermediate transfer belt was cut into a sheet measuring 50 mm in length and 50 mm in width, and the surface layer was wiped 50 times with Bemcot paper soaked in hexane at a force of 5 N. The hexadecane contact angle of the surface layer before wiping with hexane was designated A1, and the hexadecane contact angle of the surface layer after wiping with hexane was designated A2, and the contact angle change rate A2 / A1 was evaluated. In this disclosure, evaluation was performed under the above measurement conditions and using the following measurement device.

[0080] (Method for evaluating hexadecane contact angle) The hexadecane contact angle was measured on the outer surface of the surface layer of the intermediate transfer belt. A contact angle meter (product name: Portable Contact Angle Meter PCA-11, manufactured by Kyowa Interface Science Co., Ltd.) was used for the measurement. The measurement environment was 23°C and relative humidity 55%, and a 1.5μL droplet of hexadecane was dropped onto the outer surface of the surface layer. The angle between the outer surface of the surface layer and the end point of the hexadecane droplet was taken as the hexadecane contact angle, and the average value of the hexadecane contact angle measurements at three points on the outer surface of the surface layer was used as the evaluation result.

[0081] (Image forming device) The image forming apparatus is equipped with, for example, the electrophotographic member described above as an intermediate transfer member. An example of an image forming apparatus using an elastic intermediate transfer belt as the intermediate transfer member will be described with reference to FIG. 1 is a color electrophotographic image forming apparatus (color laser printer). The electrophotographic image forming apparatus 100 includes an intermediate transfer member according to one embodiment of the present disclosure as an intermediate transfer belt 7. Image forming units Py, Pm, Pc, and Pk of the respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are arranged along a flat portion of the intermediate transfer belt 7, which is the intermediate transfer member, in the moving direction of the belt.

[0082] Here, 1Y, 1M, 1C, and 1K respectively represent electrophotographic photosensitive members, 2Y, 2M, 2C, and 2K respectively represent charging rollers, 3Y, 3M, 3C, and 3K respectively represent laser exposure devices, 4Y, 4M, 4C, and 4K respectively represent developers, and 5Y, 5M, 5C, and 5K respectively represent primary transfer rollers. Since the basic configurations of the image forming units Py, Pm, Pc, and Pk are the same, details of the image forming units will only be described for the yellow image forming unit Py.

[0083] The yellow image forming unit Py has a drum-shaped electrophotographic photosensitive member 1Y (hereinafter also referred to as "photosensitive drum" or "first image carrier") as an image carrier. The photosensitive drum 1Y is formed by laminating a charge generation layer, a charge transport layer, and a surface protection layer in this order on an aluminum cylinder as a base.

[0084] The yellow image forming unit Py also includes a charging roller 2Y as a charging means. By applying a charging bias to the charging roller 2Y, the surface of the photosensitive drum 1Y is uniformly charged.

[0085] A laser exposure device 3Y is disposed above the photosensitive drum 1Y as an image exposure means. The laser exposure device 3Y scans and exposes the uniformly charged surface of the photosensitive drum 1Y in accordance with image information, forming an electrostatic latent image of a yellow color component on the surface of the photosensitive drum 1Y.

[0086] The electrostatic latent image formed on the photosensitive drum 1Y is developed with toner as a developer by a developing device 4Y as a developing means. That is, the developing device 4Y includes a developing roller 4Ya as a developer carrier and a regulating blade 4Yb as a developer amount regulating member, and also contains yellow toner as a developer. The developing roller 4Ya, to which yellow toner has been supplied, is in light pressure contact with the photosensitive drum 1Y at the developing section, and is rotated in the forward direction with a speed difference from that of the photosensitive drum 1Y. The yellow toner transported to the developing section by the developing roller 4Ya adheres to the electrostatic latent image formed on the photosensitive drum 1Y by applying a developing bias to the developing roller 4Ya. As a result, a visible image (yellow toner image) is formed on the photosensitive drum 1Y.

[0087] The intermediate transfer belt 7 is stretched around a drive roller 71, a tension roller 72, and a driven roller 73, and is moved (rotationally driven) in the direction of the arrow in the figure while in contact with the photosensitive drum 1Y. The yellow toner image formed on the photosensitive drum 1Y (first image carrier) that has reached the primary transfer section Ty is primarily transferred onto the intermediate transfer belt 7 by the primary transfer body (primary transfer roller 5Y) that is arranged opposite the photosensitive drum 1Y via the intermediate transfer belt 7.

[0088] Similarly, the above image forming operation is performed in the magenta (M), cyan (C), and black (K) image forming units Pm, Pc, and Pk as the intermediate transfer belt 7 moves, and toner images of four colors, yellow, magenta, cyan, and black, are stacked on the intermediate transfer belt 7. The four color toner layers are transported along the movement of the intermediate transfer belt 7, and at the secondary transfer portion T', they are transferred all at once onto a transfer material S (hereinafter also referred to as "second image carrier") that is transported at a predetermined timing by a secondary transfer roller 8 as a secondary transfer means. In such secondary transfer, a transfer voltage of several kV is usually applied to ensure a sufficient transfer rate.

[0089] The transfer material S is supplied to a conveying path from a cassette 12 storing the transfer material S by a pickup roller 13. The transfer material S supplied to the conveying path is conveyed to a secondary transfer portion T' in synchronization with the four-color toner image transferred to the intermediate transfer belt 7 by a conveying roller pair 14 and a registration roller pair 15.

[0090] The toner image transferred to the transfer material S is fixed by a fixing device 9 to become, for example, a full-color image. The fixing device 9 has a fixing roller 91 equipped with a heating means and a pressure roller 92, and fixes the unfixed toner image on the transfer material S by applying heat and pressure. Thereafter, the transfer material S is discharged outside the apparatus by a pair of conveying rollers 16, a pair of discharging rollers 17, etc.

[0091] A cleaning unit 11 for the intermediate transfer belt 7 is disposed downstream of the secondary transfer portion T' in the driving direction of the intermediate transfer belt 7, and removes the residual toner remaining on the intermediate transfer belt 7 without being transferred to the transfer material S at the secondary transfer portion T'.

[0092] As described above, the electrical transfer process of the toner image is repeated from the photosensitive member to the intermediate transfer belt and from the intermediate transfer belt to the transfer material. Furthermore, by repeating recording onto multiple transfer materials, the electrical transfer process is further repeated. [Example]

[0093] The present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to the following examples.

[0094] (Production of intermediate transfer belt) Example 1 (base layer) As the base layer, an endless belt made of polyimide having an inner diameter of 370 mm, a width of 370 mm, and a thickness of 80 μm was prepared.

[0095] (Primer layer) The outer peripheral surface of the base layer was irradiated with excimer UV, then a primer (product name: DY39-051A / B; manufactured by Dow Corning Toray Co., Ltd.) was applied, and the surface was heated at 160° C. for 10 minutes.

[0096] (Preparation of liquid silicone rubber mixture for elastic layer) An ionic liquid type antistatic agent (product name: FC-4400, manufactured by 3M Japan Ltd.) was used as the conductive agent. Mixture 1 was prepared by adding 0.2 parts by mass of the conductive agent to 100 parts by mass of addition-curing liquid silicone rubber (product name: TSE3032 A / B (mass ratio A1000:B8), manufactured by Momentive Performance Materials, Inc.). Next, a solution of 0.2 parts by mass of 1-ethynyl-1-cyclohexanol (manufactured by Tokyo Chemical Industry Co., Ltd.), a cure retarder, in the same mass of toluene was added to the mixture 1 to obtain a mixture 2.

[0097] Next, 0.1 parts by mass of a hydrosilylation catalyst (platinum catalyst: a mixture of 1,3-divinyltetramethyldisiloxane platinum complex, 1,3-divinyltetramethyldisiloxane, and 2-propanol) was added to mixture 2 to obtain mixture 3. Furthermore, 1.5 parts by mass of a silicone polymer (trade name: HMS-301, manufactured by Gelest) having silicon-bonded active hydrogen groups only on the side chains was weighed out as a crosslinking agent, which was added to mixture 3, thoroughly mixed, and stirred and degassed using a stirring and degassing device (trade name: HM-500, manufactured by Keyence Corporation) to obtain a liquid silicone rubber mixture.

[0098] (Formation of a laminate of a base layer and an elastic layer) Next, the polyimide belt that would become the base layer was attached to a cylindrical core, and a ring nozzle for discharging rubber was attached coaxially with the core. The liquid silicone rubber mixture was supplied to the ring nozzle using a liquid pump and discharged through a slit, thereby applying the mixture to the base layer. At this time, the relative movement speed and the discharge rate of the liquid pump were adjusted so that the thickness of the elastic layer after curing would be 260 μm. The belt attached to the core was placed in a heating furnace and heated at 180 °C for 10 minutes to perform rubber crosslinking. After cooling, the belt was removed from the core, and a belt with an elastic layer laminated thereon was obtained.

[0099] (Surface treatment of elastic layer) To improve the adhesion between the elastic layer and the surface layer, the elastic layer was surface-treated using an excimer UV irradiation unit (MDCOM) that emits a single wavelength of 172 nm. The belt with the base layer and elastic layer laminated on it was placed in a cylindrical core, and irradiated for 30 minutes in a space filled with nitrogen gas and air while rotating the core at a speed of 5 rpm from a distance of 1 mm from the surface of the excimer UV lamp.

[0100] (Surface layer) Next, a resin composition coating liquid for the surface layer was prepared using the following materials. When each material forms a silicone-grafted urethane resin, the substituents in the formulas (1) to (6) contained in the resin are also shown. (a) Polyester polyol (Product name: POLYCASTOR#30, manufactured by Ito Oil Mills, Ltd.) 99.5 parts by mass (b) One-terminal diol-modified silicone oil (Product name: X-22-176F, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass (c) Nurate-type blocked polyisocyanate (Product name: Duranate TPA-B80E, manufactured by Asahi Kasei Corporation) 91.3 parts by mass (d) 0.14 parts by mass of catalyst (product name: U-CAT 18X, manufactured by San-Apro Co., Ltd.) 2-Butanone was added as a solvent to the materials (a) to (d) and stirred for 3 hours using a roller mixer to obtain a resin composition coating liquid for the surface layer with a solid content of 20% by mass. At this time, the molar ratio (NCO / OH) of the hydroxyl groups (OH) contained in the polyol to the isocyanate groups (NCO) contained in the polyisocyanate in the resin composition was 1.0. Next, the laminate belt of the base layer and elastic layer was attached to a cylindrical core, and the resin composition coating liquid for the surface layer was sprayed onto the elastic layer so that the film thickness of the surface layer after drying would be 6 μm.The belt was then placed in a heating furnace while attached to the core, and heated at 140°C for 1 hour to harden the coating film, thereby producing an intermediate transfer belt with a surface layer formed on the elastic layer.

[0101] (Examples 2 to 13, Comparative Examples 1 to 3) An intermediate transfer belt was produced in the same manner as in Example 1 using the materials and compositions shown in Table 1. The materials listed in Table 1 are as follows. In addition, when each material forms a silicone-grafted urethane resin, the substituents (1) to (6) contained in the resin are shown. (a) Polyol Polyester polyol Example 2, Comparative Example 1: Product name: POLYCASTOR #30 (manufactured by Ito Oil Mills) Polycarbonate polyol Example 3: Product name: Nipporan 981 (manufactured by Tosoh Corporation) Polyether polyol Example 4: Polyethylene glycol 1000 (Kishida Chemical Co., Ltd.) (X 21 : an alkylene group having 2 carbon atoms, m in formula (3) is 22 to 23) Example 5: Polyethylene glycol 200 (Kishida Chemical Co., Ltd.) (X 21 : an alkylene group having 2 carbon atoms, m in formula (3) is 4 to 5) Example 6: Polypropylene glycol 400 (Kishida Chemical Co., Ltd.) (X 21 : an alkylene group having 3 carbon atoms, m in formula (3) is 8 to 9) Examples 7 to 12 and Comparative Examples 2 and 3: Polyethylene glycol 300 (Kishida Chemical Co., Ltd.) (X 21 : an alkylene group having 2 carbon atoms, m in formula (3) is 6 to 7) Glycol Example 13: 1,4-Butanediol (Kishida Chemical Co., Ltd.)

[0102] (b) Isocyanate Example 13: Nurate-type blocked polyisocyanate Duranate TPA-B80E (manufactured by Asahi Kasei Corporation) Examples 2 to 12 and Comparative Examples 2 and 3: Biuret-type blocked polyisocyanate Duranate SBB-70P (manufactured by Asahi Kasei Corporation) Comparative Example 1: Adduct-type blocked polyisocyanate Duranate E402-B80B (manufactured by Asahi Kasei Corporation)

[0103] (c) Terminally modified silicone oil Example 12: Single-terminated carbinol-modified silicone oil X-22-170DX (Shin-Etsu Chemical Co., Ltd.) Comparative Example 2: Diol-modified silicone oil (KF-6003, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0104] [Table 1]

[0105] The martensitic properties of the intermediate transfer belts obtained in Examples 1 to 13 and Comparative Examples 1 to 3 shown in Table 1 were The hardness, elastic deformation power, and silicon content of the outer surface of the surface layer were evaluated.

[0106] (Measurement of hardness and elastic deformation work using nanoindentation method) The obtained intermediate transfer belt was cut into a sheet of 20 mm length and 20 mm width, and the Martens hardness and elastic deformation power were measured by the nanoindentation method based on the procedure described above.

[0107] (Measurement of silicon element amount on outer surface by XPS) The obtained intermediate transfer belt was cut into a size of 5 mm in length and 5 mm in width, and attached to a sample stage using carbon tape with the outer surface of the surface layer facing up, and the outer surface was analyzed using an XPS device under the analysis conditions described above.

[0108] (Change in hexadecane contact angle on the outer surface of the surface layer A2 / A1) The hexadecane contact angle of the outer surface of the surface layer of the intermediate transfer belt was A1, and the hexadecane contact angle after wiping the outer surface of the surface layer 50 times with a hexane-soaked Bemcot at a force of 5 N was A2, and the contact angle change rate was A2 / A1. The measurements were performed using the procedure described above.

[0109] [evaluation] The evaluation methods for the static friction coefficient μ, hexadecane contact angle, and concentration uniformity, which are the evaluation items, are explained below. (Method for evaluating the static friction coefficient μ) The static friction coefficient μ of the outer surface of the surface layer of the intermediate transfer belt was measured. A Handy Heidon (product name: Heidon Muse TYPE; 94i-II, manufactured by Shinto Scientific Co., Ltd.) was used to measure μ. The measurement environment was 23°C and relative humidity 55%, and the average μ measured at three points on the surface layer was used as the evaluation result. If the static friction coefficient μ was 0.60 or less, it was determined that there was no problem with wear resistance.

[0110] (Method for evaluating hexadecane contact angle) The hexadecane contact angle of the surface layer of the intermediate transfer belt was measured by the procedure described above. If the hexadecane contact angle was 10° or more, it was determined that there was no problem with the toner releasability.

[0111] (Evaluation of density uniformity) The density uniformity was evaluated by mounting the intermediate transfer belts shown in the examples and comparative examples on a full-color electrophotographic image forming apparatus (product name: imagePRESS C800, manufactured by Canon Inc.). The temperature was 25°C and the relative humidity was 55%. The paper was embossed with A4 size paper (product name: Lezac 66, 250g / m 2 Solid images of secondary colors of cyan and magenta were formed on a sheet of paper (manufactured by Tokushu Tokai Seishi Co., Ltd.) and evaluated according to the following criteria. Rank A: No image unevenness is observed and it is good. Rank B: Slight image unevenness in some of the recessed areas of the embossed paper Rank C: Image unevenness in about 20% of the embossed paper recesses Rank D: Image unevenness over more than half of the embossed paper recesses In the cases of ranks A to C, the density uniformity was judged to be good.

[0112] The evaluation results for each example and comparative example are shown in Table 2. It was confirmed that each example had higher abrasion resistance and density uniformity than comparative examples 1 to 3. This is thought to be because the use of silicone-grafted urethane resin and the hardness of the surface layer and the elastic deformation power ηIT within specific ranges provided sufficient conformability to the media and improved toner releasability.

[0113] Furthermore, Examples 7 and 10 have higher density uniformity than Examples 8 and 11 and Comparative Examples 1 to 3. This is believed to be because the toner releasability can be further improved by setting the hardness and elastic deformation power ηIT of the surface layer within a specific range, as well as by setting the silicon content of the outer surface of the surface layer within a specific range. In Example 8, the amount of silicon element in the outer surface of the surface layer was low, resulting in a slightly higher static friction coefficient μ. In Example 11, diol-modified silicone oil seeped out to the outer surface of the surface layer, reducing the hexadecane contact angle, which is thought to have slightly reduced toner release properties and affected density uniformity.

[0114] It is believed that the Martens hardness of the surface layer in Comparative Example 1 was too low, resulting in poor toner release properties and poor density uniformity. It is believed that the use of a silicone oil modified with diols at both ends in Comparative Example 2 resulted in the formation of a silicone block urethane resin, which reduced the Martens hardness of the surface layer, resulting in poor density uniformity. It is believed that the static friction coefficient μ in Comparative Example 3 was very high and the hexadecane contact angle was very low, resulting in poor toner release properties and poor density uniformity.

[0115] [Table 2] The presence or absence of formulas (1) to (6) indicates whether the silicone-grafted urethane resin has each of the above structures. "-" indicates that the corresponding structure is not present.

[0116] The present disclosure relates to the following configurations. (Configuration 1) 1. An electrophotographic member having a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer, the surface layer comprises a silicone-grafted urethane resin, The elastic deformation power ηIT calculated from a load-displacement curve obtained by a nanoindentation test based on ISO 14577 in which a Vickers indenter is brought into contact with the outer surface of the surface layer and a test load of 260 μN is set to be 30 to 90%, and The Martens hardness of the outer surface of the surface layer determined by the nanoindentation test is 12 to 200 N / mm 2 Electrophotographic member characterized in that: (Configuration 2) 2. The electrophotographic member according to claim 1, wherein the amount of silicon element in the outer surface of the surface layer detected by X-ray photoelectron spectroscopy is 10 to 25 atomic % based on the total amount of Si, N, C, and O. (Configuration 3) The silicone-grafted urethane resin is At least one selected from the group consisting of a structure represented by the following formula (2-1), a structure represented by the formula (2-2), and a structure represented by the formula (2-3), and 3. The electrophotographic member according to claim 1, wherein the structure represented by the following formula (1) is contained in the molecule: TIFF2025135992000010.tif42153 In structural formula (1), R 1 ~R 3 each independently represents a linear or branched alkylene group having 1 to 12 carbon atoms. TIFF2025135992000011.tif72153 in formulas (2-1) to (2-3), X 21 ~X 23 each independently represents a linear or branched alkylene group having 1 to 12 carbon atoms. (Configuration 4) 4. The electrophotographic member according to configuration 3, wherein the silicone-grafted urethane resin has a structure represented by the following formula (3) in the molecule: TIFF2025135992000012.tif25153In structural formula (3), Z represents either a hydrogen atom or a methyl group, and m represents an integer of 3 to 30. (Configuration 5) 5. The electrophotographic member according to configuration 4, wherein in formula (3), Z is a hydrogen atom and m is an integer of 5 to 7. (Configuration 6) 6. The electrophotographic member according to any one of configurations 1 to 5, wherein the silicone-grafted urethane resin has, in its molecule, a structure represented by the following formula (4), a structure represented by the following formula (5), and a structure represented by the following formula (6): TIFF2025135992000013.tif130153In formula (4), R 41 ~R 43 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms. In formula (5), R 51 , R 52 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms. In formula (6), R 61 represents a trivalent hydrocarbon group having 1 to 12 carbon atoms. (Configuration 7) When the hexadecane contact angle of the outer surface of the surface layer is A1, and the hexadecane contact angle of the outer surface after wiping the outer surface of the surface layer 50 times with Bemcot paper soaked in hexane while applying a force of 5 N is A2, 7. The electrophotographic member according to any one of configurations 1 to 6, wherein A2 / A1 is 0.90 to 1.20. (Configuration 8) 8. The electrophotographic member according to any one of configurations 1 to 7, wherein the surface layer has a thickness of 3 to 15 μm. (Configuration 9) An electrophotographic image forming apparatus comprising the electrophotographic member according to any one of Configurations 1 to 8. (Configuration 10) 10. The electrophotographic image forming apparatus according to Configuration 9, wherein the electrophotographic member is used as an intermediate transfer member. [Explanation of symbols]

[0117] Py: yellow image forming unit, Pm: magenta image forming unit, Pc: cyan image forming unit, Pk: black image forming unit, 1Y: yellow photosensitive drum, 1M: magenta photosensitive drum, 1C: cyan photosensitive drum, 1K: black photosensitive drum, 4Y: yellow developing device, 4M: magenta developing device, 4C: cyan developing device, 4K: black developing device, 5Y, 5M, 5C, 5K: primary transfer roller, Ty, Tm, Tc, Tk: primary transfer unit, 73: secondary transfer inner roller, 100: image forming device, 2Y, 2M, 2C, 2K: charger, 3Y, 3M, 3C, 3K: laser scanner, 11: transfer belt cleaning unit, 12: paper feed cassette, 15: registration roller pair, 7: intermediate transfer belt, 8: secondary transfer outer roller, 9: fixing unit, 91: fixing film, 92: pressure roller, S: recording material 21: Base layer, 22: Elastic layer, 23: Surface layer

Claims

1. 1. An electrophotographic member having a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer, the surface layer comprises a silicone-grafted urethane resin, The elastic deformation power ηIT calculated from a load-displacement curve obtained by a nanoindentation test based on ISO 14577 in which a Vickers indenter is brought into contact with the outer surface of the surface layer and a test load of 260 μN is set to be 30 to 90%, and The Martens hardness of the outer surface of the surface layer determined by the nanoindentation test is 12 to 200 N / mm ２ Electrophotographic member characterized in that:

2. 2. The electrophotographic member according to claim 1, wherein the amount of elemental silicon in the outer surface of the surface layer detected by X-ray photoelectron spectroscopy is 10 to 25 atomic % based on the total of Si, N, C and O.

3. The silicone-grafted urethane resin is At least one selected from the group consisting of a structure represented by the following formula (2-1), a structure represented by the following formula (2-2), and a structure represented by the following formula (2-3), and 2. The electrophotographic member according to claim 1, which has a structure represented by the following formula (1) in its molecule: In structural formula (1), R １ ~R ３ each independently represents a linear or branched alkylene group having 1 to 12 carbon atoms. In formulas (2-1) to (2-3), X ２１ ~X ２３ each independently represents a linear or branched alkylene group having 1 to 12 carbon atoms.

4. 4. The electrophotographic member according to claim 3, wherein the silicone-grafted urethane resin has a structure represented by the following formula (3) in the molecule: In structural formula (3), Z represents either a hydrogen atom or a methyl group, and m represents an integer of 3 to 30.

5. 5. The electrophotographic member according to claim 4, wherein in said formula (3), Z is a hydrogen atom and m is an integer of 5 to 7.

6. 2. The electrophotographic member according to claim 1, wherein the silicone-grafted urethane resin has, in the molecule, a structure represented by the following formula (4), a structure represented by the following formula (5), and a structure represented by the following formula (6). In formula (4), R ４１ ~R ４３ are each independently a linear or branched alkyl group having 1 to 6 carbon atoms. In formula (5), R ５１ , R ５２ are each independently a linear or branched alkyl group having 1 to 6 carbon atoms. In formula (6), R ６１ represents a trivalent hydrocarbon group having 1 to 12 carbon atoms.

7. When the hexadecane contact angle of the outer surface of the surface layer is A1, and the hexadecane contact angle of the outer surface after wiping the outer surface of the surface layer 50 times with hexane-soaked Bemcot paper while applying a force of 5 N is A2, 2. The electrophotographic member of claim 1, wherein A2 / A1 is from 0.90 to 1.

20.

8. 2. The electrophotographic member according to claim 1, wherein the surface layer has a thickness of 3 to 15 μm.

9. An electrophotographic image forming apparatus comprising the electrophotographic member according to any one of claims 1 to 8.

10. 10. An electrophotographic image forming apparatus according to claim 9, wherein said electrophotographic member is provided as an intermediate transfer member.

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