Electrophotographic cleaning blade, process cartridge, and electrophotographic image forming apparatus

Abstract

To provide a cleaning blade that, even in a more accelerated process condition, can prevent the occurrence of turn-up and exhibit excellent cleaning performance even for a long-term use.SOLUTION: In a cleaning blade for electrophotography, a leading end face of an elastic member is scanned by using a scanning probe microscope; in a frequency distribution of luminance obtained from a phase image with 256 gradations, a 93rd gradation from the lowest gradation is determined as a threshold; a binarized image is created in which gradations equal to or more than the threshold are displayed in black and gradations less than the threshold are displayed in white; the binarized image is divided into 100 sections with sides of 2 μm. The coefficient of variation of the area ratio of white areas based on the area ratio of the white area in each section, the average value AM of the area ratios of the white areas, and the standard deviation Σ of the area ratios of the white areas is 20.00 or less. A value obtained by subtracting the Martens hardness HM2 of the elastic member from the Martens hardness HM1 at a specific position is larger than 0.10 N / mm2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrophotographic cleaning blade, a process cartridge, and an electrophotographic image forming apparatus. [Background technology]

[0002] Electrophotographic devices are equipped with a cleaning member to remove toner remaining on an image carrier after a toner image is transferred from an image carrier such as a photoreceptor to a transfer medium such as paper or an intermediate transfer medium. A cleaning blade having a plate-shaped elastic member is often used as the cleaning member. In recent years, toner particles have become smaller in size due to demands for higher image quality in electrophotographic images, making cleaning with a cleaning blade more difficult.

[0003] Under these circumstances, Patent Document 1 discloses a cleaning blade that can exhibit excellent cleaning performance, which includes an elastic member containing urethane rubber and a support member that supports the elastic member, and has an edge at the free end portion of the elastic member and a first surface and a second surface that constitute the edge, at least one of the first surface and the second surface having a hardened surface and specific physical properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-77466 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the study by the present inventors, it has been found that there is still room for improvement in the resistance to peeling under severe usage conditions of the cleaning blade disclosed in Patent Document 1. Specifically, for example, when used for a long period of time in an electrophotographic image forming apparatus with a high process speed, peeling may occur, resulting in a deterioration in cleaning performance. One aspect of the present disclosure is to provide an electrophotographic cleaning blade that can exhibit excellent cleaning performance even under severe usage conditions. Another aspect of the present disclosure is to provide a process cartridge and an electrophotographic image forming apparatus that contribute to the stable formation of high-quality electrophotographic images. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, The device includes an elastic member containing polyurethane and a support member that supports the elastic member, An electrophotographic cleaning blade that cleans the surface of a moving member to be cleaned by bringing a part of the elastic member into contact with the surface of the member to be cleaned, When the side of the cleaning blade that contacts the surface of the member to be cleaned is defined as the tip side of the cleaning blade, the elastic member has a plate shape at least on the tip side, the plate shape having a main surface facing the member to be cleaned and a tip surface forming a tip edge together with the main surface; When it is assumed that a first line segment is drawn on the tip surface parallel to the tip edge at a distance of 10 μm from the tip edge, The length of the first line segment is L, When the point 1 / 2L from one end of the first line segment is P1, a square region of the tip surface having a center of gravity at P1, a side length of 20 μm, and a side parallel to the first line segment, is scanned using a scanning probe microscope at a scan speed of 1 Hz and with 256 vertical and 256 horizontal scan points, to obtain a grayscale phase image of 256 gradations as a viscoelastic image of the region; a binary image is created in which the 93rd gradation from the lowest gradation in the luminance frequency distribution obtained from the phase image is used as a threshold, and values ​​equal to or greater than this threshold are represented as black and values ​​below this threshold are represented as white; the binary image is further divided into 100 sections of 2 μm square, and a coefficient of variation of the area ratio of the white region is calculated based on the area ratio of the white region in each section, the average value AM of the area ratio of the white region, and the standard deviation Σ of the area ratio of the white region, and the coefficient of variation is 20.00% or less; From the Martens hardness HM1 of the elastic member measured at the position P1, Assuming that a bisector of the angle formed by the main surface and the tip surface is drawn on a cross section of the elastic member that is perpendicular to the tip surface and the tip edge, including P1, the Martens hardness HM2 of the elastic member measured at a position on the bisector that is 500 μm away from the tip edge is 0.10 N / mm 2 A larger electrophotographic cleaning blade is provided.

[0007] According to another aspect of the present disclosure, there is provided a process cartridge having the electrophotographic cleaning blade. Furthermore, according to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus having the electrophotographic cleaning blade. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide an electrophotographic cleaning blade that can exhibit excellent cleaning performance even under severe usage conditions. Also, according to another aspect of the present disclosure, it is possible to provide a process cartridge and an electrophotographic image forming apparatus that contribute to the stable formation of high-quality electrophotographic images. [Brief explanation of the drawings]

[0009] [Figure 1] Schematic perspective view of an electrophotographic cleaning blade [Figure 2] Schematic cross-sectional view of an electrophotographic cleaning blade in contact with a member to be cleaned. [Figure 3] A diagram showing a first line segment whose distance from the leading edge is 10 μm [Figure 4] A diagram showing a point 1 / 2L from one end of the first line segment [Figure 5] Diagram showing the location of P1 [Figure 6] Diagram showing a square with a side length of 20 μm and center of gravity at P1 [Figure 7] Diagram showing the position where Martens hardness HM2 is measured DETAILED DESCRIPTION OF THE INVENTION

[0010] In the present disclosure, unless otherwise specified, the expressions "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit. When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way. Examples of members to be cleaned that can be used with the electrophotographic cleaning blade according to one aspect of the present disclosure (hereinafter also simply referred to as "cleaning blade") include image carriers such as photoreceptors, endless belts such as intermediate transfer belts, etc. Hereinafter, an embodiment of the cleaning blade according to the present disclosure will be described in detail using an image carrier as an example of the member to be cleaned, but the present disclosure is not limited thereto.

[0011] <Cleaning blade configuration> 1 is a schematic perspective view of a cleaning blade according to one embodiment of the present disclosure. The cleaning blade 1 includes an elastic member 2 and a support member 3 that supports the elastic member 2.

[0012] 2 is a cross-sectional view showing a state in which a cleaning blade according to one embodiment of the present disclosure is in contact with a member to be cleaned. The cleaning blade 1 cleans the surface of the member to be cleaned 8 by bringing a part of the elastic member 2 into contact with the surface of the moving member to be cleaned 8. When the side of the cleaning blade 1 that contacts the surface of the member 8 to be cleaned is defined as the tip side of the cleaning blade, the elastic member 2 has a plate shape at least on the tip side, having a main surface 5 that faces the member 8 to be cleaned and a tip surface 6 that forms a tip edge 7 together with the main surface 5. In FIG. 2, 4 indicates the tip, 10 indicates the surface opposite to the main surface 5, 11 indicates the surface on which the support member 3 is installed, and R indicates the direction of rotation of the member to be cleaned.

[0013] The present inventors have found that a cleaning blade having an embodiment that satisfies, for example, the requirements (1) and (2) described below can suppress curling at the contact portion with the member to be cleaned, even under harsh usage conditions, and can exhibit excellent cleaning performance.

[0014] (1) When it is assumed that a first line segment is drawn on the tip surface of the cleaning blade parallel to the tip edge and at a distance of 10 μm from the tip edge, The length of the first line segment is L, A point 1 / 2L from one end on the first line segment is designated as P1 (see FIGS. 3, 4, and 5). A square region of the tip surface, centered at P1, with a side length of 20 μm and parallel to the first line segment (see FIG. 6 ), is scanned using a scanning probe microscope at a scan speed of 1 Hz and 256 vertical and 256 horizontal scan points to obtain a 256-level grayscale phase image as a viscoelastic image of the region. A binary image is then created in which the 93rd lowest gray level in the luminance frequency distribution obtained from the phase image is used as a threshold, with values ​​above this threshold represented as black and values ​​below this threshold represented as white. The binary image is then divided into 100 2 μm square sections, and the coefficient of variation of the white area ratio is calculated based on the white area ratio, the average value AM of the white area ratios, and the standard deviation Σ of the white area ratios in each section. The coefficient of variation thus obtained is 20.00% or less. Preferably, the coefficient of variation is 10.00% or less. The lower limit of the coefficient of variation is 0.00%. The coefficient of variation (%) is calculated as (100×Σ / AM) where AM is the average value of the area ratio and Σ is the standard deviation of the area ratio.

[0015] The polyurethane contained in the elastic member is usually composed of hard segments and soft segments. The hard segments and soft segments have different elastic moduli. The "white areas" in the binarized image above indicate areas with a relatively higher elastic modulus than the "black areas."

[0016] Conventional polyurethanes (e.g., polyurethane elastomers) typically contain large hard segments due to aggregation of hard segments. Furthermore, the hard and soft segments vary in density. A cleaning blade made of such polyurethane may experience uneven contact pressure along its length against the cleaning target. This unevenness can cause unstable contact at the leading edge, leading to curling under high-speed processing conditions. On the other hand, as described above, the cleaning blade according to the present disclosure has a coefficient of variation of the area ratio of the white region of 20.00 or less, and therefore the density unevenness of the hard segment and the soft segment is small and the hard segment and the soft segment are present more uniformly than in conventional polyurethanes. Therefore, even when the cleaning blade is applied to a higher-speed electrophotographic image forming process, the occurrence of curling of the cleaning blade can be suppressed.

[0017] The average area ratio AM of the white regions is preferably 45.0% or more, more preferably 55.0% or more, and even more preferably 65.0% or more. The average value AM of the area ratio of the white regions is preferably 80.0% or less, and more preferably 75.0% or less. When the average value AM of the area ratio of the white regions satisfies the above range, it becomes easier to adjust the coefficient of variation of the area ratio of the white regions to fall within the above range, and cleaning performance can be further improved.

[0018] (2) Assuming that a bisector of the angle between the main surface and the tip surface is drawn on a cross section of the elastic member that is perpendicular to the tip surface and tip edge including P1, the Martens hardness HM1 of the elastic member measured at the position P1 minus the Martens hardness HM2 of the elastic member measured at a position 500 μm away from the tip edge on the bisector (see FIG. 7) is 0.10 N / mm 2 Greater than. The value obtained by subtracting HM2 from HM1 is 0.14N / mm 2 It is preferable that the resistance is 0.25N / mm or more. 2 On the other hand, the value obtained by subtracting HM2 from HM1 is 5.00 N / mm 2 Below, especially 3.00N / mm 2 It is preferable that:

[0019] One way to increase the value obtained by subtracting HM2 from HM1 is to use a surface treatment, which increases the elastic modulus of the cleaning blade surface and increases the surface hardness. By hardening the vicinity of the tip edge that contacts the member to be cleaned, curling is less likely to occur. On the other hand, if the entire cleaning blade is hard, it becomes difficult to absorb disturbances such as micro-vibrations caused by rubbing against the member to be cleaned and vibrations of the device, and curling tends to occur more easily under high-speed process conditions. Therefore, as disclosed herein, the value obtained by subtracting the Martens hardness HM2 from the Martens hardness HM1 is set to 0.10 N / mm 2 By making it larger, even when the electrophotographic image forming process is accelerated, the occurrence of curling of the cleaning blade can be more reliably suppressed.

[0020] [Support member] The material constituting the support member of the cleaning blade is not particularly limited, and examples thereof include the following: metal materials such as steel plate, stainless steel plate, zinc-plated steel plate, and chrome-free steel plate; and resin materials such as 6-nylon and 6,6-nylon. The structure of the support member is also not particularly limited. One end of the elastic member of the cleaning blade is supported by the support member, as shown in FIG. 2 etc.

[0021] [Elastic member] The polyurethane contained in the elastic member is preferably a polyurethane elastomer. Polyurethane elastomers are obtained primarily from raw materials such as polyols, chain extenders, polyisocyanates, catalysts, and other additives. The polyurethane elastomer is a block copolymer composed of a hard segment and a soft segment. One non-limiting method for obtaining a cleaning blade having a white area variation coefficient of 20.00% according to the present disclosure is to utilize the properties of the block copolymer composed of the hard segment and the soft segment.

[0022] Conventional polyurethanes have relatively large hard segments formed by further aggregation of urethane bond aggregates formed by the interaction of urethane bonds. Therefore, according to the studies of the present inventors, wiper blades made using conventional polyurethanes do not satisfy the coefficient of variation according to the present disclosure. In other words, because conventional polyurethanes have relatively large hard segments, it is difficult to achieve a coefficient of variation of 20.00% or less in the white region.

[0023] The cleaning blade according to one embodiment of the present disclosure may be formed, for example, from polyurethane in which hard segments are finely and uniformly dispersed. Several examples of polyurethanes in which hard segments are finely and uniformly dispersed will be described below, although the constituent material of the elastic portion according to the present disclosure is not limited to these polyurethanes. As urethane raw materials, diisocyanates and multifunctional isocyanates with three or more functional groups are used. By using an alcohol or a polyfunctional alcohol having three or more functional groups in an appropriate concentration range, aggregation of the hard segments is suppressed, and a polyurethane in which the hard segments are finely and uniformly dispersed can be obtained.

[0024] Specifically, for example, alcohols including polyfunctional alcohols having three or more functional groups, and trifunctional alcohols At least one of the above polyfunctional isocyanate compounds is used as a urethane It is preferable to use it as a raw material. It is also preferable to use, as urethane raw materials, an alcohol containing at least one selected from diols and tri- or higher functional alcohols, and an isocyanate compound containing tri- or higher functional isocyanate. In addition, alcohols containing trifunctional or higher polyfunctional alcohols and diisocyanates and trifunctional alcohols are also used. It is used as a urethane raw material together with an isocyanate compound containing a multifunctional isocyanate of 100% or more. It is particularly preferable to use a tri- or higher functional polyfunctional alcohol and a tri- or higher functional polyfunctional isocyanate as the urethane raw material.

[0025] Polyurethanes obtained as reaction products of tri- or higher functional alcohols and tri- or higher functional isocyanates have molecular orientation suppressed by steric hindrance, and aggregation of hard segments is more reliably suppressed, making them suitable for achieving the elastic modulus and coefficient of variation according to the present disclosure. Furthermore, when the soft segment portion has, for example, a linear alkylene structure, the soft segments stack together, increasing crystallinity. As a result, the hard segments also become difficult to disperse. Therefore, introducing an alkylene structure with a side chain into the soft segment portion is also effective in suppressing the aggregation of the hard segments. Specifically, for example, introducing a partial structure such as that shown in the following structural formulas (i) to (iv) into the soft segment portion between two urethane bonds is effective in miniaturizing the hard segments. -CH2-CH(CH3)-CH2-CH2-O- (i) -CH2-CH2-CH(CH3)-CH2-O- (ii) -CH2-CH(CH3)-O- (iii) -CH(CH3)-CH2-O- (iv)

[0026] The structures of structural formulas (i) and (ii) are substantially identical to each other and are generated by ring-opening polymerization of 3-methyltetrahydrofuran. Furthermore, the structures of structural formulas (iii) and (iv) are substantially identical to each other and are generated by ring-opening polymerization of 1,2-propylene oxide. Urethane resins having these structures between two adjacent urethane bonds can be obtained by reacting a polyether polyol or polyester polyol having these structures with an isocyanate. When a bifunctional alcohol (diol) and a bifunctional isocyanate (diisocyanate) are used as urethane raw materials, it is usually difficult to finely disperse the hard segments. However, by introducing the above partial structure into the soft segment, it is possible to finely disperse the hard segments, even when a diol and a diisocyanate are used as urethane raw materials. As a result, a polyurethane can be obtained that provides a wiper blade that satisfies the parameters of the present disclosure.

[0027] In addition to introducing side chains into the soft segment portions, One method for suppressing crystallization due to stacking and preventing aggregation of hard segments is to use two or more alcohols with different carbon numbers in the linear chain portion as the alcohols of the urethane raw material. Polyurethanes obtained using two or more alcohols with different carbon numbers in the linear chain portion can suppress crystallization due to stacking of soft segments, even if the soft segments have a linear alkylene structure due to the different carbon numbers. Furthermore, the different carbon numbers in the soft segments suppress aggregation of urethane bonds, thereby preventing aggregation of hard segments. Therefore, even when diols and diisocyanates having a linear alkylene structure in their molecules are used as urethane raw materials, using multiple diols with different carbon numbers in the linear alkylene structure as the diols can achieve finer hard segments. As a result, polyurethanes that provide wiper blades that satisfy the parameters of the present disclosure can be obtained. An example of multiple diols is the combined use of polybutylene adipate polyester polyol and polyhexylene adipate polyester polyol.

[0028] Examples of alcohols that can be used as urethane raw materials include the following polyols. Polyester polyols such as polyethylene adipate polyester polyol, polybutylene adipate polyester polyol, polyhexylene adipate polyester polyol, (polyethylene / polypropylene) adipate polyester polyol, (polyethylene / polybutylene) adipate polyester polyol, and (polyethylene / polyneopentylene) adipate polyester polyol; polycaprolactone-based polyols obtained by ring-opening polymerization of caprolactone; polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; and polycarbonate diols. These can be used alone or in combination of two or more.

[0029] Among the above polyols, polyester polyols using adipate are preferred because they give polyurethane elastomers with excellent mechanical properties. Furthermore, those using methylene groups having 4 or more carbon atoms, such as polybutylene adipate polyester polyol and polyhexylene adipate polyester polyol, are more preferred. It is also preferable to use polyols having different numbers of carbon atoms in the methylene group, such as polybutylene adipate polyester polyol and polyhexylene adipate polyester polyol, in combination.

[0030] In addition, using two or more polyols with different numbers of carbon atoms in the linear chain portion (alkylene chain) as the alcohol is preferable because it suppresses crystallization of the soft segment and allows for the production of a urethane in which aggregation of the hard segment is suppressed. In this case, it is preferable to use at least two selected from the group consisting of polyester polyols such as polyethylene adipate polyester polyol, polybutylene adipate polyester polyol, polyhexylene adipate polyester polyol, (polyethylene / polypropylene) adipate polyester polyol, (polyethylene / polybutylene) adipate polyester polyol, and (polyethylene / polyneopentylene) adipate polyester polyol.

[0031] As the chain extender, a diol capable of extending the polyurethane elastomer chain or a polyfunctional alcohol having three or more functional groups can also be used. Examples of diols include the following: Ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD), 1,6-hexanediol (1,6-HD), 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylylene glycol (terephthalyl alcohol), triethylene glycol. These can be used alone or in combination of two or more.

[0032] Examples of trifunctional or higher polyfunctional alcohols include trimethylolpropane (TMP), glycerin, pentaerythritol, and sorbitol, which can be used alone or in combination of two or more.

[0033] One method for generating the "white regions" of the binarized image, that is, regions with a relatively high modulus of elasticity, is to introduce a crosslinked structure. As a method for introducing a crosslinked structure, for example, a trifunctional or higher polyfunctional alcohol is preferably used as the chain extender. Furthermore, the introduction of a branched structure into polyurethane using a trifunctional or higher polyfunctional alcohol can suppress the crystallization of the polyurethane and further suppress the aggregation of hard segments. Here, a trifunctional alcohol is preferably used as the polyfunctional alcohol from the viewpoint of suppressing an excessive increase in hardness due to an excessively high degree of crosslinking of the polyurethane. Among these, triols, which have a methylene skeleton next to a hydroxyl group and can form a flexible crosslinked structure in terms of molecular structure, are more preferred because they have an even greater effect of suppressing the crystallinity of hard segments. Examples of such triols include trimethylolpropane (TMP) and glycerin.

[0034] Examples of isocyanates include the following: 4,4'-Diphenylmethane Diisocyanate (4,4'-MDI), Polymeric MDI, 2,4-Tolylene Diisocyanate (2,4-TDI), 2,6-Tolylene Diisocyanate (2,6-TDI), Xylene Diisocyanate (XDI), 1,5-Naphthylene Diisocyanate (1,5-NDI), p-Phenylene Diisocyanate (PPDI), Hexamethylene Diisocyanate (HDI), Isophorone Diisocyanate (IPDI), 4,4'-Dicyclohexylmethane Diisocyanate (Hydrogenated MDI), Tetramethylxylene Diisocyanate (TMXDI), Carbodiimide-Modified MDI, Triphenylmethane-4,4',4''-Triisocyanate (TTI), Tris(phenylisocyanate)thiophosphate (TPTI).

[0035] Among these, 4,4'-MDI is preferred because the two isocyanate groups have equal reactivity and high mechanical properties are obtained. It is also preferred to use a tri- or higher-functional polyfunctional isocyanate in combination. The use of a tri- or higher-functional polyfunctional isocyanate allows a branched structure to be introduced into the polyurethane, which is effective in further suppressing aggregation of hard segments. Furthermore, a denser crosslinked structure can be introduced into the polyurethane, which can more stably contact the elastic portion with the cleaning target. As a result, incomplete wiping and uneven wiping of the cleaning target can be more effectively suppressed. Examples of tri- or higher-functional polyfunctional isocyanates include at least one selected from the group consisting of triphenylmethane-4,4',4''-triisocyanate (TTI), tris(phenylisocyanate)thiophosphate (TPTI), and polymeric MDI. Among these, tris(phenylisocyanate)thiophosphate (TPTI) and polymeric MDI are more preferably used. These isocyanates have methylene or ether groups between multiple NCO groups, which allows the distance between multiple urethane bonds to be maintained appropriately, which is advantageous in suppressing aggregation of hard segments.

[0036] Here, polymeric MDI is represented by the following chemical formulas (1-1) and (1-2). In chemical formula (1-2), n represents an integer of 2 or more. There is no particular upper limit for n, but it is preferably 4 or less, for example. Note that chemical formula (1-1) corresponds to the structure when n is 1 in chemical formula (1-2).

[0037] [ka]

[0038] The content of the tri- or higher functional isocyanate in the polyisocyanate is preferably 0.5% by mass to 20.0% by mass, and more preferably 1.0% by mass to 19.5% by mass.

[0039] The catalyst may be a commonly used catalyst for curing polyurethane elastomers, such as a tertiary amine catalyst. Specific examples include the following: aminoalcohols such as dimethylethanolamine, N,N,N'-trimethylaminopropylethanolamine, and N,N'-dimethylhexanolamine; trialkylamines such as triethylamine; tetraalkyldiamines such as N,N,N'N'-tetramethyl-1,3-butanediamine; triethylenediamine, piperazine-based compounds, and triazine-based compounds. Organic acid salts of metals such as potassium acetate and potassium alkali octylate may also be used. Furthermore, metal catalysts typically used in urethanization, such as dibutyltin dilaurate, may also be used. These may be used alone or in combination of two or more.

[0040] In addition to polyurethane, the raw materials constituting the elastic member may contain additives such as pigments, plasticizers, waterproofing agents, antioxidants, ultraviolet absorbers, and light stabilizers, as required.

[0041] In the elastic member, the angle of the tip edge formed by the main surface and the tip surface is not particularly limited, but is usually about 85 to 95 degrees. Furthermore, in the present disclosure, the hardness of the elastic member is preferably in the range of 65 to 90 degrees. Note that in the present disclosure, the hardness (IRHD) of the elastic member is a value measured using a Wallace microhardness tester manufactured by Wallace, Inc., according to the International Rubber Hardness Test M Method. The International Rubber Hardness Test M Method is specified in JIS K6253-1997.

[0042] One method for adjusting the coefficient of variation of the area ratio of the above-mentioned white area within a predetermined range and adjusting the value obtained by subtracting HM2 from HM1 within a predetermined range is to form a hardened area on the surface of the cleaning blade using a known method. Specific methods are described below, but are not limited to these.

[0043] The hardened area of ​​the elastic member preferably includes the main surface and the tip surface that forms the tip edge together with the main surface. The hardened area may also include other surfaces, i.e., the surface opposite to the main surface and the surface on which the support member is installed (the surface indicated by reference numerals 10 and 11 in FIG. 2), and the longitudinal edge of the elastic member. The elastic member may be formed on both end surfaces in the hand direction, in which case the rigidity of both end surfaces of the elastic member can be improved, and curling of the cleaning blade can be further reduced.

[0044] The method for forming the hardened region in the polyurethane contained in the elastic member is not particularly limited, and any known method such as a method using ultraviolet light or a method of applying and hardening a material for forming the hardened region may be used. The degree of hardening may also be appropriately selected by adjusting the coefficient of variation of the area ratio of the white region described above to a predetermined range, and adjusting the value obtained by subtracting HM2 from HM1 to a predetermined range.

[0045] Hereinafter, as a specific example, a method of applying and curing a material for forming a hardened region will be described, but the present invention is not limited to this. The material for forming the hardened region may be diluted with a diluting solvent as necessary and applied to the hardened region by known means such as dipping, spraying, using a dispenser, brushing, or roller application. The material for forming the hardened region may be an isocyanate compound, which will be described later. In this case, the material for forming the hardened region (such as an isocyanate compound) may be sufficiently impregnated into the polyurethane contained in the elastic member. Since impregnation is promoted by using a high concentration and low viscosity of the material for forming the hardened region, the material for forming the hardened region may be heated without dilution. The degree of hardening may be adjusted by the temperature of the material for forming the hardened region, the impregnation or immersion time, the temperature and time of heat treatment after impregnation or immersion, the subsequent leaving time, and the like.

[0046] An example of a method for forming a hardened region will be described below using an isocyanate compound as the material for forming the hardened region. The elastic member coated with the material for forming the hardened region may be referred to as a "precursor." As described above, after applying the material for forming the hardened region to the hardened region, the precursor is preferably heat-treated. The temperature of the material for forming the hardened region is preferably about 60°C to 80°C. The impregnation or immersion time is not necessarily fixed, but is preferably about 10 to 60 seconds. The heat treatment reduces the viscosity of the material for forming the hardened region present on the surface of the polyurethane, thereby facilitating its penetration and diffusion into the interior of the polyurethane.

[0047] The heating method may be, but is not particularly limited to, a method of passing the precursor through a heating furnace, a method of blowing heated air onto the precursor, etc. For example, the heating furnace may be a radiation heating furnace or a circulating air heating furnace, and the device for generating heated air may be a hot air blower or a far-infrared heater.

[0048] By setting the heating conditions to a high temperature and / or a long time, the hardened region becomes wider and the elasticity becomes higher. As for the heating conditions, it is preferable that the surface temperature of the treated surface is, for example, 90°C to 110°C. Furthermore, it is preferable that the heating time is, for example, 10 minutes to 30 minutes. Furthermore, the amount of residual isocyanate during polyurethane molding tends to gradually decrease over time after molding. Therefore, the formation of the cured region should be carried out promptly after polyurethane molding, but is not particularly limited. For example, it is recommended to carry out the formation within 3 hours. The amount of residual isocyanate can also be adjusted by the mixing ratio of the composition used during polyurethane formation.

[0049] The material for forming the hardened region is not particularly limited as long as it is capable of hardening polyurethane or forming a hardened region on the surface of polyurethane. Examples of the material include an isocyanate compound and an acrylic resin. The material for forming the hardened region may be diluted with a solvent before use. The solvent used for dilution is a solvent that dissolves the material to be used. There are no particular limitations on the solvent as long as it is soluble in water, and examples thereof include toluene, xylene, butyl acetate, methyl isobutyl ketone, and methyl ethyl ketone.

[0050] When the constituent material of the polyurethane is a polyurethane elastomer, it is preferable to use an isocyanate compound, which is a constituent material of the polyurethane elastomer, as the material for forming the hardened region, in consideration of compatibility with the polyurethane and impregnation into the polyurethane. The isocyanate compound to be brought into contact with the polyurethane may be one having one or more isocyanate groups in the molecule. As the isocyanate compound having one isocyanate group in the molecule, an aliphatic monoisocyanate such as octadecyl isocyanate (ODI), an aromatic monoisocyanate such as phenyl isocyanate (PHI), or the like can be used. As the isocyanate compound having two isocyanate groups in the molecule, those compounds usually used in the production of polyurethane resins can be used, and specific examples thereof include the following: 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (MDI), m-phenylene diisocyanate (MPDI), tetramethylene diisocyanate (TMDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. As the isocyanate compound having three or more isocyanate groups in the molecule, for example, 4,4',4''-triphenylmethane triisocyanate, 2,4,4'-biphenyl triisocyanate, 2,4,4'-diphenylmethane triisocyanate, etc. can be used. In addition, modified derivatives and polymers of isocyanate compounds having two or more isocyanate groups in the molecule can also be used. Among them, MDI, which has high crystallinity, i.e., a symmetric structure, is preferred to efficiently increase the hardness of the cured region. Furthermore, MDI containing modified compounds is preferred from the viewpoint of workability, as it is liquid at room temperature. In the cured region, there are usually both a portion where the polyurethane is impregnated with isocyanate and cured, and a portion where the isocyanate or the like on the surface of the polyurethane is cured.

[0051] The method for manufacturing the cleaning blade may be selected from known methods as appropriate, and is not particularly limited. The method for manufacturing the elastic member may be selected from known methods such as a mold molding method and a centrifugal molding method. For example, a support member having an adhesive applied to the portion that comes into contact with the elastic member is placed in a mold for molding a cleaning blade that has a cavity for forming the elastic member. Meanwhile, a prepolymer formed by partially polymerizing polyisocyanate and polyol, as well as a curing agent containing polyol, chain extender, catalyst, and other additives, are placed in a casting machine. Then, using a mixing chamber or the like, they are mixed and stirred at a fixed ratio to obtain a raw material composition such as a polyurethane elastomer. This raw material composition is injected into the mold to form a cured molded product (elastic member) on the adhesive-coated surface of the support member, and the mold is removed after reaction and curing. If necessary, the elastic member can be appropriately cut to the specified dimensions or to ensure the dimensional accuracy of the edge of the contact portion of the elastic member, thereby producing a cleaning blade precursor in which the support member and elastic member are molded integrally.

[0052] Another method is to place two adhesive-coated support members facing each other in a mold cavity, inject a raw material composition into the mold through openings at the longitudinal end faces, and cause a curing reaction at 100°C to 150°C to obtain a molded product in which the two support members are integrated by the polyurethane elastomer.The urethane portion of this molded product is then cut in the center near the hand to separate it into two pieces, and the urethane portions are further cut and removed along both longitudinal ends of the holder, thereby producing two cleaning blades. When the raw material composition is injected into the cavity of this mold, it is preferable to tilt the casting mold by 5° to 20° so that the raw material composition flows first over one of the two support members. By setting the tilt angle within the above range, air trapped in the center of the two blades is less likely to remain. This also prevents the raw material composition from hardening before reaching the end of the cavity, which would be caused by a slower flow of the raw material composition during injection. Furthermore, by returning the tilt angle of the tilted casting mold to 0° before injection of the raw material composition into the mold is complete, the filling time can be shortened, further preventing the occurrence of insufficient filling.

[0053] When the elastic member is manufactured using a centrifugal molding machine, a prepolymer obtained by partially polymerizing polyisocyanate and polyol, a curing agent containing polyol, a chain extender, a catalyst, and other additives, is mixed and stirred to obtain a raw material composition such as a polyurethane elastomer. This is then placed in a rotating drum to obtain a polyurethane elastomer sheet. This polyurethane elastomer sheet is then cut to the desired dimensions and to ensure the edge dimensional accuracy of the contact portion of the elastic member. The polyurethane elastomer sheet (elastic member) thus obtained can be attached to a support member coated with an adhesive to produce a cleaning blade precursor.

[0054] The hardened region can be formed by the method already described. That is, first, the material for forming the hardened region is applied to the main surface and tip surface of the elastic member of the cleaning blade precursor. Next, the applied portion is heat-treated, for example, at a temperature of 90°C or higher for 10 minutes or more. This allows hardened regions to be formed on the surface and inside of the applied portion.

[0055] When it is necessary to cut the elastic member to form the leading edge of the cleaning blade, the hardened region may be formed before or after the cutting. In the case of centrifugal molding, the hardened region may be formed before the elastic member is joined to the support member. In this manner, a cleaning blade can be obtained.

[0056] <Process cartridge and electrophotographic image forming apparatus> The cleaning blade according to the present disclosure can be incorporated into a process cartridge for an electrophotographic image forming apparatus and used therein. The process cartridge according to the present disclosure is a process cartridge having the electrophotographic cleaning blade according to the present disclosure. The cleaning blade can also be incorporated into an electrophotographic image forming apparatus.The electrophotographic image forming apparatus according to the present disclosure is an electrophotographic image forming apparatus having the cleaning blade for electrophotography according to the present disclosure. [Example]

[0057] The present disclosure will be described below with reference to Production Examples, Examples, and Comparative Examples, but the present disclosure is not limited to these Examples. Reagents or industrial chemicals were used as raw materials other than those indicated in the Examples and Comparative Examples. Note that "parts" in the Examples and Comparative Examples are all by mass unless otherwise specified.

[0058] <Measuring and calculating area ratios M1 to M100, average area ratio AM, standard deviation of area ratio Σ, and coefficient of variation (100×Σ / AM)> Measurements were made using a scanning probe microscope (hereinafter referred to as SPM), and calculations were made using the following method. The scanning probe microscope (SPM) used was an MFP-3D-Origin (Oxford Instruments). The measurement sample was prepared as follows. Assuming that a first line segment is drawn on the tip surface of the cleaning blade parallel to the tip edge and at a distance of 10 μm from the tip edge, the length of the first line segment is L, and the point 1 / 2L from one end of the first line segment is P1, the tip surface is set at P1 as the center of gravity. A measurement sample was cut out from the measurement sample, measuring 2 mm square, with one side parallel to the first line segment. Next, a 100 μm square, 1 μm thick polyurethane slice was cut out from the measurement sample at -50°C using a cryomicrotome (UC-6 (product name), manufactured by Leica Microsystems) with P1 as the center of gravity and one side parallel to the first line segment. The measurement sample was thus prepared. The obtained measurement sample was placed on a smooth silicon wafer and left to stand for 24 hours in an environment of room temperature 25°C and humidity 50%.

[0059] Next, the silicon wafer with the measurement sample mounted on it was set on the SPM stage and observed using the SPM. The spring constant and proportionality constant of the silicon cantilever (product name: OMCL-AC160, manufactured by Olympus, tip curvature radius: 8 nm) were previously confirmed to be as follows using the thermal noise method installed in this SPM device: spring constant: 30.22 nN / nm, proportionality constant: 82.59 nm / V. Furthermore, the cantilever was tuned in advance to determine the resonance frequencies of the cantilever (285 KHz (first order) and 1.60 MHz (higher order)).

[0060] The SPM measurement mode was AM-FM viscoelastic mapping mode, the cantilever free amplitude was 3V (primary) and 25mV (higher order), and the set point amplitude was 2V (primary).A square (20μm x 20μm) area with P1 as the center of gravity, each side 20μm long, and one side parallel to the first line segment was scanned at a scan speed of 1Hz and 256 vertical and 256 horizontal scan points, and a 256-level grayscale phase image was obtained as a viscoelastic image of the area. The obtained phase image was binarized using an image processing analysis system (trade name: Luzex-AP, manufactured by Nireco Corporation). Specifically, a binarized image was created in which the 93rd lowest gray level in the luminance frequency distribution obtained from the phase image was used as a threshold, with values ​​above this threshold represented as black and values ​​below this threshold represented as white. The binarized image was then divided into 100 2-μm square sections (M1 to M100). For each section (M1 to M100), the white area ratio (M1 to M100) relative to the section area, the average value AM of the white area ratios, and the standard deviation Σ of the white area ratios were calculated. Furthermore, the coefficient of variation (100 × Σ / AM: unit "%)" of the white area ratios was calculated.

[0061] <Method for measuring Martens hardness> The Martens hardness was measured by the following method. Assuming that a first line segment is drawn on the tip surface of the cleaning blade parallel to the tip edge at a distance of 10 μm from the tip edge, the length of the first line segment is L, and a point 1 / 2L from one end of the first line segment is P1, the Martens hardness of the elastic member measured at the position P1 is HM1. On the other hand, assuming that a bisector of the angle between the main surface and the tip surface is drawn on a cross section of the elastic member that is perpendicular to the tip surface and tip edge including P1, the Martens hardness of the elastic member measured at a position on the bisector that is 500 μm away from the tip edge is defined as HM2. Microhardness tester: Shimadzu Corporation, model: DUH-211S Measurement environment: temperature 23±5℃ Measuring indenter: Triangular pyramidal indenter 115° (ridge angle 115°) Measurement mode: Depth setting test Depth setting: 2 μm Load speed: 0.03mN / sec Hold time: 5 seconds Calculation formula: Martens hardness = 1000F / 26.43h 2 [N / mm 2 〕 F: Test force (mN), h: Indentation depth (μm)

[0062] In this example, an integrally molded cleaning blade as shown in FIG. 1 was manufactured and evaluated.

[0063] Example 1 <Supporting member> A 1.6 mm thick zinc-plated steel plate was prepared and processed to obtain a support member with an L-shaped cross section, as shown by reference numeral 3 in Figure 2. A urethane-metal single-layer adhesive (product name: Chemlok 219, manufactured by Lord Corporation) was applied to the area of ​​this support member that would come into contact with the elastic member.

[0064] <Preparation of raw materials for elastic members> The materials in Table 1 below were mixed and reacted at a temperature of 80° C. for 3 hours to obtain a prepolymer with an NCO content of 10.0% by mass.

[0065] [Table 1]

[0066] The materials shown in Table 2 below were mixed to prepare a curing agent.

[0067] [Table 2]

[0068] The prepolymer and the curing agent were mixed to prepare a raw material composition for a polyurethane elastomer. The adhesive-coated portion of the previously prepared support member was positioned so that it protruded into the cavity of the mold for molding a cleaning blade. Next, the above-mentioned raw material composition was poured into the mold for molding a cleaning blade and cured at a temperature of 130°C for 2 minutes. After that, the mold was demolded to obtain an integrally molded body of polyurethane elastomer and support member. Note that prior to molding, release agent A was applied to the inside of the mold for molding a cleaning blade. Release agent A was a mixture of materials shown in Table 3.

[0069] [Table 3]

[0070] The tip end of this integrally molded polyurethane elastomer was cut to create a plate-shaped elastic member having a main surface and a tip surface that, together with the main surface, constitutes a tip edge. The tip edge angle was 90 degrees, and the elastic member's width, thickness, and length were 7.5 mm, 1.8 mm, and 240 mm, respectively.

[0071] <Formation of hardened area> Carbodiimide-modified MDI (trade name: Millionate MTL, manufactured by Tosoh Corporation) was used as a material for forming the hardened region. The five surfaces of the elastic member, excluding the surface on which the support member was installed (reference numeral 11 in Fig. 2), were immersed in the material for forming the hardened region heated to a temperature of 70°C for 20 seconds, and the material for forming the hardened region was applied to each surface. The time elapsed from the completion of molding of the elastic member to the start of formation of the hardened region (hereinafter also referred to as "leaving time") was 1 hour. Next, the material for forming the hardened region on the surface of the elastic member was wiped off using a sponge soaked in butyl acetate solvent. The elastic member was then heat-treated in an electric furnace at 100°C for 10 minutes, causing the material for forming the hardened region impregnated in the elastic member to diffuse into the interior of the elastic member and harden. This resulted in a cleaning blade 1 with hardened regions formed on five surfaces of the elastic member (main surface, tip surface, surface opposite the main surface, and both longitudinal end surfaces) and beneath these surfaces. The cleaning blades thus obtained were evaluated by the following methods. The results of each evaluation are shown in Table 4.

[0072] [Evaluation 1] Average value of the area ratio of the white area (AM) and coefficient of variation of the area ratio of the white area According to the measurement and calculation methods described above, the area ratio of the white area to the area of ​​each section (M1 to M100): M1 to M100 was calculated, the average value AM of the white area ratio was calculated, and the standard deviation Σ of the white area ratio was calculated. From this, the coefficient of variation of the white area ratio was calculated according to (100 × Σ / AM: unit "%)".

[0073] [Evaluation 2] Martens hardness difference The Martens hardness difference was determined according to the above-mentioned measurement method.

[0074] [Evaluation 3] Cleaning blade performance evaluation <Production of Toner 1> (Preparation step of aqueous medium 1) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, 650.0 parts of ion-exchanged water and 14.0 parts of sodium phosphate (Rasa Kogyo Co., Ltd., 12-hydrate) were added, and the mixture was kept at 65°C for 1.0 hour while purging with nitrogen. Aqueous medium containing a dispersion stabilizer was prepared by adding an aqueous calcium chloride solution prepared by dissolving 9.2 parts of calcium chloride (dihydrate) in 10.0 parts of ion-exchanged water all at once while stirring at 15,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) Further, 10% by mass of hydrochloric acid was added to the aqueous medium to adjust the pH to 5.0, thereby obtaining aqueous medium 1.

[0075] (Preparation step of polymerizable monomer composition) Styrene: 60.0 parts CI Pigment Blue 15:3:6.5 parts The materials were placed in an attritor (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.), and further dispersed using zirconia particles with a diameter of 1.7 mm at 220 rpm for 5.0 hours to prepare a pigment dispersion. The following materials were added to the pigment dispersion. Styrene: 20.0 parts n-Butyl acrylate: 20.0 parts Crosslinking agent (divinylbenzene): 0.3 parts Saturated polyester resin: 5.0 parts (Polycondensation polymer of propylene oxide-modified bisphenol A (2-mol adduct) and terephthalic acid (molar ratio 10:12), glass transition temperature Tg = 68°C, weight average molecular weight Mw = 10,000, molecular weight distribution Mw / Mn = 5.12) Fischer-Tropsch wax (melting point 78°C): 7.0 parts The mixture was kept at 65°C and uniformly dissolved and dispersed at 500 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a polymerizable monomer composition.

[0076] (granulation process) While maintaining the temperature of the aqueous medium 1 at 70°C and the rotation speed of the TK homomixer at 15,000 rpm, the polymerizable monomer composition was charged into the aqueous medium 1, and 10.0 parts of t-butyl peroxypivalate as a polymerization initiator was added. Granulation was continued for 10 minutes while maintaining the stirring speed at 15,000 rpm with the stirring device. (Polymerization and distillation processes) After the granulation step, the agitator was replaced with a propeller agitator blade, and the mixture was stirred at 150 rpm while maintaining the temperature at 70°C for 5.0 hours to carry out polymerization. The temperature was then raised to 85°C and heated for 2.0 hours to carry out the polymerization reaction. Thereafter, the reflux piping of the reaction vessel was replaced with a cooling pipe, and the slurry was heated to 100° C. to carry out distillation for 6 hours to remove unreacted polymerizable monomers, thereby obtaining a toner base particle dispersion liquid.

[0077] (Polymerization of organosilicon compounds) 60.0 parts of ion-exchanged water was weighed into a reaction vessel equipped with a stirrer and a thermometer, and the pH was adjusted to 4.0 with 10% by mass of hydrochloric acid. This was heated with stirring until the temperature reached 40°C. Then, 40.0 parts of methyltriethoxysilane, an organosilicon compound, was added and stirred for 2 hours or more to carry out hydrolysis. The end point of the hydrolysis was confirmed by visual inspection when the oil and water were no longer separated and a single layer was formed, and the mixture was cooled to obtain a hydrolyzed solution of the organosilicon compound. The resulting toner base particle dispersion was cooled to 55°C, and 25.0 parts of the organosilicon compound hydrolyzate was added to initiate polymerization of the organosilicon compound. After 15 minutes of incubation, the pH was adjusted to 5.5 with a 3.0% by weight aqueous solution of sodium bicarbonate. After 60 minutes of incubation at 55°C with continued stirring, the pH was adjusted to 9.5 with a 3.0% by weight aqueous solution of sodium bicarbonate, and the mixture was further incubated for 240 minutes to obtain a toner particle dispersion.

[0078] (Washing and drying process) After the polymerization process was completed, the toner particle dispersion was cooled, and hydrochloric acid was added to the toner particle dispersion to adjust the pH to 1.5 or less, and the dispersion was left to stand with stirring for 1 hour, after which solid-liquid separation was carried out using a pressure filter to obtain a toner cake. This was reslurried with ion-exchanged water to make a dispersion again, and then solid-liquid separation was carried out using the above-mentioned filter to obtain a toner cake. The obtained toner cake was dried and classified in a thermostatic chamber at 40° C. for 72 hours, and toner 1 was obtained.

[0079] <Cleaning performance evaluation> Cleaning blade 1 was incorporated into a cyan cartridge of a color laser beam printer (product name: HP LaserJet Enterprise Color M553dn, manufactured by Hewlett-Packard Company) as a cleaning blade for the photosensitive drum, which is the member to be cleaned. Further, the toner in the developing machine of the cyan cartridge was completely replaced with the above-mentioned Toner 1. Next, images were formed on 12,500 sheets, which is the maximum number of sheets that can be printed, in a low temperature and low humidity environment (temperature 15° C., relative humidity 10%) (hereinafter referred to as "normal evaluation"). Furthermore, in the developing machine used, the toner was replaced with a new cyan cartridge in which all the toner was replaced with Toner 1, and image formation was again performed on 12,500 sheets, which is the maximum number of printable sheets (hereinafter referred to as "double evaluation"). The evaluation was carried out while the waste toner was sucked out from the rear of the cartridge as needed. The images obtained were evaluated according to the following criteria. Rank A: Image defects (streaks on the image) caused by the cleaning blade do not occur in either the normal evaluation or the double evaluation. Rank B: Image defects (streaks on the image) caused by the cleaning blade do not occur in the normal evaluation, but occur slightly in the double evaluation (streaks 5 mm or less in length). Rank C: Image defects (streaks on the image) caused by the cleaning blade do not occur in the normal evaluation, but do occur in the double evaluation (streaks longer than 5 mm but less than 10 mm). Rank D: Image defects (streaks on the image) caused by the cleaning blade do not occur in the normal evaluation, but do occur (more than 10 mm) in the 2x evaluation. Rank E: Image defects (streaks on the image) caused by the cleaning blade occur in both the normal evaluation and the double evaluation. Furthermore, the color laser beam printer used in the above evaluation was modified to change the rotation speed of the photosensitive drum from 170 rpm to 300 rpm, but the evaluation was carried out in the same manner as above.

[0080] [Evaluation 4] Evaluation of cleaning blade curl In the above evaluation of cleaning performance, no peeling or abnormal noise was observed. In evaluation 4, the cleaning blade was evaluated for curling under higher speed process conditions and long-term use as follows.

[0081] Cleaning blade 1 was incorporated into a new cyan cartridge separate from the one used for the evaluation of cleaning performance, as a cleaning blade for the photosensitive drum, which is the member to be cleaned. In addition, the toner in the developing machine of the cyan cartridge was completely replaced with the above-mentioned toner 1. Next, 15,000 images were formed in a low-temperature environment (temperature 0°C). The cartridge, with the developing unit removed, was then set in an idle rotating machine (a device equipped with a jig that holds the cartridge while rotating the photosensitive drum). Under the same conditions, the photosensitive drum was rotated at 170 rpm, and the condition of the tip of the cleaning blade was observed for 10 minutes. This observation was performed by processing the cartridge and installing a CCD camera. Evaluation was based on the following criteria. Rank A: No peeling or abnormal noises (vibration noises) occur. Rank B: No peeling occurs, but a slight abnormal noise (buzzing noise) occurs. Rank C: No peeling occurs, but an abnormal noise (vibration) occurs. Rank D: Peeling occurs. Furthermore, the evaluation was carried out in the same manner as above, except that the rotation speed of the photosensitive drum was changed from 170 rpm to 300 rpm.

[0082] Examples 2 to 12 Cleaning blades 2 to 12 were obtained in the same manner as in Example 1, except that the temperature and immersion time of the material for forming the hardened region, as well as the heat treatment temperature, heat treatment time, and leaving time (the time from molding the elastic member to forming the hardened region) were changed to the conditions shown in Table 4.

[0083] Example 13 A cleaning blade according to this example was fabricated in the same manner as in Example 1, except that the hardened region was formed only on the leading edge surface. Specifically, the material for forming the hardened region used in Example 1 was heated to 80°C and applied to the leading edge surface of the elastic member using a dispenser. The standing time from the completion of molding the elastic member to the start of hardened region formation was 1 hour. After the application of the material for forming the hardened region was completed, the integrally molded body was left in an environment of 25°C and 50% relative humidity for 10 minutes. Next, the integrally molded body was heat-treated in an electric furnace at 100°C for 10 minutes, allowing the material for forming the hardened region impregnated into the elastic member to diffuse into the interior of the elastic member and harden. In this manner, a cleaning blade 13 according to this example was obtained. Table 4 shows the evaluation results of the cleaning blades according to Examples 1 to 13.

[0084] [Table 4]

[0085] Comparative Example 1 A cleaning blade H1 according to this comparative example was produced in the same manner as in Example 1, except that no hardened region was formed.

[0086] Comparative Example 2 <Preparation of raw materials for elastic members> The materials shown in Table 5 below were reacted at 80° C. for 3 hours with stirring to obtain a prepolymer with an NCO content of 8.50%.

[0087] [Table 5]

[0088] A curing agent was prepared by mixing the materials in Table 6 below.

[0089] [Table 6]

[0090] The prepolymer and the mixture were mixed to obtain a raw material composition for a polyurethane elastomer. A cleaning blade H2 according to this comparative example was obtained in the same manner as in Example 1, except that the raw material composition thus obtained was used.

[0091] Comparative Example 3 Cleaning blade H3 was obtained in the same manner as in Comparative Example 2, except that the temperature and immersion time of the material for forming the hardened region, as well as the heat treatment temperature, heat treatment time, and leaving time (the time from molding the elastic member to forming the hardened region) were changed to the conditions shown in Table 7. Table 7 shows the evaluation results of the cleaning blades according to Comparative Examples 1 to 3.

[0092] [Table 7]

[0093] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2020-186348, filed on November 9, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0094] 1: cleaning blade, 2: elastic member, 3: support member, 4: tip portion, 5: main surface, 6: tip surface, 7: tip edge, 8: member to be cleaned, 10: surface opposite to the main surface, 11: surface on the side where the support member is installed, R: rotation direction of the member to be cleaned

Claims

1. An electrophotographic cleaning blade that cleans the surface of a moving member to be cleaned by bringing a part of the elastic member into contact with the surface of the member, The electrophotographic cleaning blade comprises: an elastic member comprising polyurethane; and a support member that supports the elastic member Equipped with When the side of the electrophotographic cleaning blade that comes into contact with the surface of the member to be cleaned is defined as the tip side of the electrophotographic cleaning blade, the elastic member has a plate shape at least on the tip side, the plate shape having a main surface facing the member to be cleaned and a tip surface forming a tip edge together with the main surface; a first line segment is drawn on the tip surface parallel to the tip edge at a distance of 10 μm from the tip edge; The length of the first line segment is L, A point 1 / 2L from one end of the first line segment is designated as P1. A square region of the tip surface, having a center of gravity at P1, with a side length of 20 μm and one side parallel to the first line segment, is scanned using a scanning probe microscope at a scan speed of 1 Hz and with 256 vertical and 256 horizontal scan points; A 256-level grayscale phase image is acquired as a viscoelastic image of the region. a binary image is created in which the 93rd lowest gray level in the luminance frequency distribution obtained from the phase image is used as a threshold value, and values ​​equal to or greater than the threshold value are displayed as black, and values ​​less than the threshold value are displayed as white; The binarized image was divided into 100 sections of 2 μm square, and the coefficient of variation of the area ratio of the white area was calculated based on the area ratio of the white area in each section, the average value AM of the area ratio of the white area, and the standard deviation Σ of the area ratio of the white area. The coefficient of variation is 20.00 or less, The Martens hardness of the elastic member measured at the position P1 is defined as HM1, When a bisector of the angle formed by the main surface and the tip surface is drawn on a cross section of the elastic member that is perpendicular to the tip surface and the tip edge, including P1, and the Martens hardness of the elastic member measured at a position on the bisector that is 500 μm away from the tip edge is defined as HM2, The value obtained by subtracting HM2 from HM1 is 0.10 N / mm ２ Bigger, The polyurethane is obtained as a reaction product of an alcohol and an isocyanate compound, The alcohol includes a polyfunctional alcohol having three or more functional groups, The isocyanate compound includes a polyfunctional isocyanate having three or more functionalities. Electrophotographic cleaning blade.

2. 2. The cleaning blade for electrophotography according to claim 1, wherein the average area ratio AM of the white regions is 45.0% or more.

3. The alcohol comprises trimethylolpropane, The isocyanate compound includes polymeric MDI.

3. The cleaning blade for electrophotography according to claim 1 or 2.

4. The alcohol comprises polybutylene adipate polyester polyol, polyhexylene adipate polyester polyol, and trimethylol propane; The isocyanate compound includes 4,4'-diphenylmethane diisocyanate and polymeric MDI. The cleaning blade for electrophotography according to any one of claims 1 to 3.

5. A process cartridge comprising the electrophotographic cleaning blade according to any one of claims 1 to 4.

6. An electrophotographic image forming apparatus having the electrophotographic cleaning blade according to any one of claims 1 to 4.

Images