Cleaning blade for electrophotography, process cartridge, and electrophotographic image forming apparatus

Abstract

The present invention provides a cleaning blade for electrophotography, characterized in that: a front end surface of an elastic member is scanned using a scanning probe microscope; a binary image is created in which values ​​greater than or equal to a threshold value are displayed in black and values ​​less than the threshold value are displayed in white, wherein the threshold value is the 93rd grayscale from the lowest grayscale side in a brightness frequency distribution obtained from a 256-grayscale phase image; the binary image is divided into 100 partitions, each of which is a square of 2 μm; a coefficient of variation of the area ratio of the white area based on the area ratio of the white area in each partition, an average value AM of the area ratio of the white area, and a standard deviation Σ of the area ratio of the white area is 20.00 or less; and a value obtained by subtracting the Martens hardness HM2 from the Martens hardness HM1 at a specific position in the elastic member is greater than 0.10 N / mm 2 .

Description

Technical Field

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

[0002] Electrophotographic apparatuses are equipped with a cleaning member to remove residual toner from an image bearing member, such as a photosensitive member, after the toner image has been transferred from the image bearing member to a transfer receiving member, such as paper or an intermediate transfer member. A cleaning blade having a plate-shaped elastic member is typically used as the cleaning member. To meet the growing demand for higher image quality in electrophotographic images in recent years, toner particles are becoming smaller, making cleaning with a cleaning blade increasingly difficult.

[0003] In this context, patent document 1 discloses a cleaning scraper, which is a cleaning scraper capable of achieving excellent cleaning performance. The cleaning scraper is provided with an elastic member having polyurethane rubber and a supporting member supporting the elastic member, and the cleaning scraper has an edge at the free end of the elastic member and a first surface and a second surface constituting the edge, at least one of the first surface and the second surface has a cured surface and has specific physical properties.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-77466 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The inventors' research has revealed that there is still room for improvement in the resistance to tuck-up of the cleaning blade according to Patent Document 1 under severe usage conditions. Specifically, for example, as a result of long-term use in an electrophotographic image forming apparatus at a high processing speed, tuck-up may occur and cleaning performance may deteriorate.

[0009] One aspect of the present disclosure is to provide an electrophotographic cleaning blade that can achieve 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 facilitate stable formation of high-quality electrophotographic images.

[0010] Solutions for solving problems

[0011] According to one aspect of the present disclosure, there is provided:

[0012] A cleaning blade for electrophotography, comprising:

[0013] an elastic member comprising polyurethane; and

[0014] a supporting member that supports the elastic member, and

[0015] The surface of the member to be cleaned is cleaned by causing a portion of the elastic member to contact the surface of the member to be cleaned while moving, wherein

[0016] 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,

[0017] The elastic member has a plate shape at least on the front end side, the plate shape having a main surface facing the member to be cleaned and a leading end surface forming a front end side edge together with the main surface;

[0018] Assume that a first line segment is drawn on the top end surface parallel to the front end side edge and 10 μm away from the front end side edge.

[0019] where the length of the first line segment is denoted by L, and

[0020] The point on the first line segment that is 1 / 2L away from one end side is represented by P1;

[0021] When a square area of ​​the top surface is scanned by using a scanning probe microscope under conditions involving a scanning speed of 1 Hz and 256 vertical scanning points and 256 horizontal scanning points to acquire a grayscale phase image of 256 grayscale levels as a viscoelastic image of the area, the square area has a center of gravity at P1, has a side length of 20 μm, and has one side parallel to the first line segment,

[0022] In the brightness frequency distribution obtained from the phase image, a binarized image was created with the 93rd gray level from the lowest gray level side as a threshold value so that the portion above the threshold value was depicted in black and the portion below the threshold value was depicted in white, the binarized image was divided into 100 sections each being a 2-μm square, and

[0023] When the coefficient of variation of the area ratio of the white area is obtained based on the area ratio of the white area in each partition, 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,

[0024] The coefficient of variation is less than 20.00; and

[0025] Assuming that a line bisecting the angle formed by the main surface and the top end surface is drawn on a cross section of the elastic member perpendicular to the top end surface and the front end side edge including P1,

[0026] The value obtained by subtracting the Martens hardness HM2 of the elastic member measured at a position 500 μm from the front end side edge on the bisector from the Martens hardness HM1 of the elastic member measured at the position P1 is greater than 0.10 N / mm 2 .

[0027] In another aspect of the present disclosure, a process cartridge having the electrophotographic cleaning blade described above is provided. In still another aspect of the present disclosure, an electrophotographic image forming apparatus having the electrophotographic cleaning blade described above is provided.

[0028] Effects of the Invention

[0029] According to one aspect of the present disclosure, there is provided an electrophotographic cleaning blade capable of providing excellent cleaning performance under severe usage conditions. According to another aspect of the present disclosure, there is provided a process cartridge and an electrophotographic image forming apparatus that facilitate stable formation of high-quality electrophotographic images. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] [ Figure 1 ] is a schematic perspective view of a cleaning blade for electrophotography.

[0031] [ Figure 2 ] is a schematic cross-sectional view of a state in which a cleaning blade for electrophotography is in contact with a member to be cleaned.

[0032] [ Figure 3 ] is a diagram showing a first line segment 10 μm away from the front end side edge.

[0033] [ Figure 4 ] is a diagram showing a point on the first line segment that is 1 / 2L away from one end side.

[0034] [ Figure 5 ] is a diagram showing the position of P1.

[0035] [ Figure 6 ] is a diagram showing a square with a center of gravity at P1 and a side length of 20 μm.

[0036] [ Figure 7 ] is a diagram showing the position for measuring the Martens hardness HM2. DETAILED DESCRIPTION

[0037] In the present disclosure, the description of "XX or more and YY or "XX to YY" to express a numerical range means that the numerical range includes the lower limit and the upper limit as endpoints, unless otherwise specified. When the numerical range is specified in stages, the upper and lower limits of each numerical range can be arbitrarily combined.

[0038] Examples of the member to be cleaned to which the cleaning blade for electrophotography according to one aspect of the present disclosure (hereinafter, also simply referred to as a "cleaning blade") is applied include an image bearing member such as a photosensitive member and an endless belt such as an intermediate transfer belt. An embodiment of the cleaning blade according to one aspect of the present disclosure will be described in detail below by illustrating an image bearing member as an example of the member to be cleaned; however, the present invention is not limited thereto.

[0039] <Structure of Cleaning Blade>

[0040] Figure 1 1 is a schematic perspective view of a cleaning blade according to one aspect of the present disclosure. The cleaning blade 1 includes an elastic member 2 and a supporting member 3 that supports the elastic member 2 .

[0041] Figure 2 A portion of the elastic member 2 of the cleaning blade 1 contacts the surface of the member 8 to be cleaned while the cleaning blade 1 is moving, thereby cleaning the surface of the member 8 to be cleaned.

[0042] The side of the cleaning blade 1 that contacts the surface of the member to be cleaned 8 is defined as the front end side of the cleaning blade. The elastic member 2 has, at least on the front end side, a main surface 5 facing the member to be cleaned 8 and a top end surface 6 that forms a front end side edge 7 together with the main surface 5.

[0043] exist Figure 2 4, reference numeral 10 denotes a front end portion, reference numeral 10 denotes a surface opposite to the main surface 5, reference numeral 11 denotes a surface on a side where the support member 3 is mounted, and reference numeral R denotes a rotation direction of the member to be cleaned.

[0044] The present inventors have found that, for example, a cleaning blade satisfying requirements (1) and (2) described below suppresses occurrence of curling at a contact area with a member to be cleaned and provides excellent cleaning performance even under severe use conditions.

[0045] (1) Assume that a first line segment is drawn on the top end surface of the cleaning blade parallel to the front end side edge and 10 μm away from the front end side edge,

[0046] The length of the first line segment is defined as L;

[0047] The point on the first line segment that is 1 / 2L away from one end side is defined as P1 (see Figure 3 、 Figure 4 and Figure 5 ),

[0048] Using a scanning probe microscope, a square area (see FIG1 ) with a center of gravity at P1, a side length of 20 μm, and a top face having one side parallel to the first line segment was scanned under conditions involving a scanning speed of 1 Hz, 256 vertical scanning points, and 256 horizontal scanning points. Figure 6 ), thereby obtaining a grayscale phase image of 256 grayscale levels as the viscoelastic image of the above-mentioned area. In the brightness frequency distribution obtained from the phase image, the threshold is set at the 93rd grayscale from the lowest grayscale side, thereby creating a binary image in which the portion above the threshold is depicted in black and the portion below the threshold is depicted in white. The binary image is further divided into 100 partitions, each of which is a square with a side length of 2 μm, and then the area ratio of the white area and the coefficient of variation of the area ratio of the white area are calculated based on the average value AM of the area ratio of the white area in each partition and the standard deviation Σ of the area ratio of the white area. The coefficient of variation thus obtained is less than 20.00%. The coefficient of variation is preferably less than 10.00%. 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.

[0049] The polyurethane contained in the elastic member is generally composed of hard segments and soft segments. The hard segments and soft segments have different elastic moduli. The "white area" in the above binary image indicates an elastic modulus that is relatively higher than the elastic modulus in the "black area".

[0050] Conventional polyurethanes (e.g., polyurethane elastomers) typically have large hard segments due to hard segment aggregation. Furthermore, the density of the hard and soft segments may be unevenly distributed. Cleaning blades made from such polyurethanes may exhibit uneven contact pressure on the member being cleaned in the longitudinal direction of the cleaning blade. It is believed that this unevenness causes the contact state at the leading edge to become unstable, leading to curling under high-speed processing conditions.

[0051] In contrast, in the cleaning blade according to the present disclosure, as described above, the coefficient of variation of the area ratio of the white region is 20.00 or less. As a result, the density distribution of the hard and soft segments is less uneven, and the hard and soft segments are more uniformly distributed than in conventional polyurethanes. Therefore, even when the cleaning blade is used in increasingly high-speed electrophotographic image formation processes, the occurrence of curling of the cleaning blade can be suppressed.

[0052] 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. In contrast, the average area ratio AM of the white regions is preferably 80.0% or less, and more preferably 75.0% or less.

[0053] When the average value AM of the area ratio of the white regions satisfies the above range, the coefficient of variation of the area ratio of the white regions can be easily adjusted to be within the above range, and the cleaning performance can be further improved.

[0054] (2) Assuming that a line bisecting the angle formed by the main surface and the top end surface is drawn on a cross section of the elastic member perpendicular to the top end surface and the front end side edge including P1, the Martens hardness HM2 of the elastic member measured at a position 500 μm away from the front end side edge on the bisecting line is subtracted from the Martens hardness HM1 of the elastic member measured at the position P1 (see Figure 7 ) greater than 0.10N / mm 2 .

[0055] The value obtained by subtracting HM2 from HM1 is preferably 0.14 N / mm 2 More than, more preferably 0.25N / mm 2 In contrast, the value obtained by subtracting HM2 from HM1 is preferably 5.00 N / mm 2 Below, more preferably 3.00N / mm 2 the following.

[0056] Methods for increasing the value obtained by subtracting HM2 from HM1 include methods such as surface treatment, etc. The surface treatment increases the elastic modulus of the cleaning blade surface and enhances the hardness of the surface.

[0057] By hardening the vicinity of the front end side edge that contacts the member being cleaned, the occurrence of curling becomes less likely. In contrast, when the cleaning blade as a whole becomes harder, it becomes difficult to absorb disturbances such as microvibrations caused by friction with the member being cleaned and vibrations of the device, and curling is more likely to occur under processing conditions involving higher speeds. Therefore, by specifying that the value obtained by subtracting the Martens hardness HM2 from the Martens hardness HM1 is greater than 0.10 N / mm as in the present disclosure, 2 , even when the speed of the electrophotographic image forming process increases, it becomes possible to more reliably suppress the occurrence of rolling up of the cleaning blade.

[0058] [Supporting member]

[0059] The material of the support member constituting the cleaning blade is not particularly limited, and examples thereof include the following materials. For example, metal materials such as steel plate, stainless steel plate, galvanized steel plate, chromium-free steel plate, and resin materials such as 6-nylon and 6,6-nylon. Likewise, the structure of the support member is not particularly limited. One end of the elastic member of the cleaning blade is supported by the support member, for example, Figure 2 shown.

[0060] [Elastic member]

[0061] The polyurethane contained in the elastic member is preferably a polyurethane elastomer.

[0062] Polyurethane elastomers are mainly obtained from starting materials such as polyols, chain extenders, polyisocyanates, catalysts and other additives.

[0063] The polyurethane elastomer is a block copolymer composed of hard segments and soft segments. Here, according to the present disclosure, a non-limiting method for obtaining a cleaning blade having a coefficient of variation of white area of ​​20.00% involves utilizing the properties of the block copolymer composed of the hard segments and soft segments.

[0064] In conventional polyurethanes, the aggregated portions of urethane bonds resulting from the aggregation of urethane bonds have relatively large hard segments resulting from further aggregation. Consequently, the present inventors' research has revealed that wiper blades produced using such conventional polyurethanes do not meet the coefficient of variation specified in the present disclosure. Specifically, conventional polyurethanes have relatively large hard segments, making it difficult to reduce the coefficient of variation of the white region to below 20.00%.

[0065] The cleaning blade according to one aspect of the present disclosure may be formed, for example, by fine and uniform dispersion of the hard segment.

[0066] Several examples of polyurethanes in which hard segments are finely and uniformly dispersed will be explained below. However, the constituent material of the elastic portion according to the present disclosure is not limited to these polyurethanes.

[0067] By using polyurethane starting materials in the form of diisocyanate or trifunctional or higher polyfunctional isocyanate and diol or trifunctional or higher polyfunctional alcohol, a polyurethane produced by fine and uniform dispersion of hard segments with suppressed hard segment aggregation can be obtained within an appropriate concentration range.

[0068] Specifically, for example, it is preferable to use at least one selected from alcohols including trifunctional or higher polyfunctional alcohols and isocyanate compounds including trifunctional or higher polyfunctional isocyanates as the polyurethane starting material.

[0069] Furthermore, it is preferred to use an alcohol including at least one selected from diols and trifunctional or higher polyfunctional alcohols and an isocyanate compound including trifunctional or higher polyfunctional isocyanate as the polyurethane starting material.

[0070] It is also preferred to use alcohols including trifunctional or higher polyfunctional alcohols and isocyanate compounds including diisocyanates and trifunctional or higher polyfunctional isocyanates as polyurethane starting materials. It is particularly preferred to use trifunctional or higher polyfunctional alcohols and trifunctional or higher polyfunctional isocyanates as polyurethane starting materials.

[0071] Due to steric hindrance, the polyurethane obtained as the reaction product of a trifunctional or higher polyfunctional alcohol and a trifunctional or higher polyfunctional isocyanate exhibits suppressed molecular orientation, which further reliably suppresses hard segment aggregation. As a result, the polyurethane is suitable for achieving the elastic modulus and coefficient of variation according to the present disclosure.

[0072] In addition, in the case where the soft segment portion has, for example, a linear alkylene structure, the crystallinity is improved by stacking the soft segments. As a result, the hard segments are not easily dispersed. Therefore, introducing an alkylene structure having a side chain portion into the soft segment portion is also effective in suppressing the aggregation of the hard segments. Specifically, for example, introducing a substructure such as those shown by the following structural formulas (i) to (iv) into the soft segment portion between the two urethane bonds is effective in reducing the hard segments.

[0073] -CH2-CH(CH3)-CH2-CH2-O- (i)

[0074] -CH2-CH2-CH(CH3)-CH2-O- (ii)

[0075] -CH2-CH(CH3)-O- (iii)

[0076] -CH(CH3)-CH2-O- (iv)

[0077] The structures in the substantially identical structural formulas (i) and (ii) are produced by the ring-opening polymerization of 3-methyltetrahydrofuran. The structures in the substantially identical structural formulas (iii) and (iv) are produced by the ring-opening polymerization of 1,2-propylene oxide. By reacting a polyether polyol or polyester polyol having these structures with an isocyanate, a polyurethane resin having these structures between two adjacent urethane bonds can be obtained. In the case where difunctional alcohols (diols) and difunctional isocyanates (diisocyanates) are used as polyurethane starting materials, it is generally difficult to achieve fine dispersion of the hard segments. However, even when diols and diisocyanates are used, the hard segments can be finely dispersed by introducing the above-mentioned substructures into the soft segment portion. As a result of obtaining a wiper blade that meets the parameters according to the present disclosure, a polyurethane can be obtained.

[0078] In addition to introducing side chains into the soft segment as described above, methods for suppressing crystallization from soft segment stacking and preventing hard segment aggregation include, for example, methods involving the use of two or more alcohols having linear moieties with different numbers of carbon atoms as the alcohol in the polyurethane starting material. In polyurethanes obtained by using two or more alcohols having linear moieties with different numbers of carbon atoms, crystallization from soft segment stacking can also be suppressed due to the different carbon numbers, especially when the soft segment has a linear alkylene structure. Given that the carbon numbers in the soft segment are thus different, aggregation of the urethane bond moieties is suppressed, resulting in the prevention of hard segment aggregation. Therefore, in cases where a diisocyanate and a diol having a linear alkylene structure in the molecule are used as the polyurethane starting materials, the hard segment can also be reduced by using multiple diols having different numbers of carbon atoms in the linear alkylene structure as the diols. As a result, a polyurethane can be obtained that meets the parameters of the present disclosure. Examples of the plurality of types of diols include, for example, simultaneous use of polybutylene adipate polyester polyol and polyhexamethylene adipate polyester polyol.

[0079] Examples of the alcohol as a starting material for the polyurethane include, for example, the following polyols.

[0080] Polyester polyols, such as polyethylene adipate polyester polyol, polybutylene adipate polyester polyol, polyhexamethylene adipate polyester polyol, poly(ethylene glycol / propylene glycol) adipate polyester polyol, poly(ethylene glycol / butylene glycol) adipate polyester polyol, and poly(ethylene glycol / neopentyl glycol) 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. The foregoing can be used alone or in combination of two or more.

[0081] Among the above-mentioned polyols, it is preferable to use polyester polyol of adipate ester, because in this case, a polyurethane elastomer exhibiting excellent mechanical properties is obtained.

[0082] More preferably, a polyol having an alkylene group having 4 or more carbon atoms, such as polybutylene adipate polyester polyol or polyhexamethylene adipate polyester polyol, is used.

[0083] Preferably, polyols having different numbers of alkylene carbon atoms are used simultaneously here, for example polybutylene adipate polyester polyol and polyhexylene adipate polyester polyol.

[0084] As described above, as the alcohol, it is preferred to use two or more polyols having linear moieties (alkylene chains) having different numbers of carbon atoms, because in this case, a polyurethane in which soft segment crystallization is suppressed and hard segment aggregation is suppressed is obtained. In this case, it is preferred to use, for example, at least two selected from the group consisting of polyester polyols such as polyethylene adipate polyester polyol, polybutylene adipate polyester polyol, polyhexane adipate polyester polyol, poly(ethylene glycol / propylene glycol) adipate polyester polyol, poly(ethylene glycol / butylene glycol) adipate polyester polyol, and poly(ethylene glycol / neopentyl glycol) adipate polyester polyol.

[0085] As the chain extender, a diol or a trifunctional or higher-functional alcohol that can extend the polyurethane elastomer chain may be used.

[0086] Examples of the diols include the following.

[0087] 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, xylene glycol (terephthalate glycol), and triethylene glycol. The foregoing can be used alone or in combination of two or more.

[0088] Examples of trifunctional or higher polyfunctional alcohols include trimethylolpropane (TMP), glycerol, pentaerythritol, and sorbitol. The foregoing may be used alone or in combination of two or more.

[0089] One method for generating "white areas" in a binarized image, ie, areas of relatively high elastic modulus, may include, for example, the introduction of cross-linked structures.

[0090] The preferred method of introducing a cross-linked structure includes using a trifunctional or higher polyfunctional alcohol as a chain extender. By using a trifunctional or higher polyfunctional alcohol, a branched structure is introduced into the polyurethane so as to suppress polyurethane crystallization and further suppress hard segment aggregation. From the viewpoint of suppressing the excessive increase in hardness caused by the excessive cross-linking degree of the polyurethane, preferably, a trifunctional alcohol is used as the polyfunctional alcohol. Triols are preferred among the aforementioned because these have a methylene skeleton adjacent to a hydroxyl group, which can produce a flexible cross-linked structure in the molecular structure and induce the effect of further suppressing hard segment crystallization. Examples of such triols include, for example, trimethylolpropane (TMP) and glycerol.

[0091] Examples of the isocyanate include the following.

[0092] 4,4'-MDI, polymeric MDI, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), xylene diisocyanate (XDI), 1,5-naphthalene 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), and tris(phenylisocyanate)phosphorothioate (TPTI).

[0093] Among the aforementioned, 4,4'-MDI is preferred because its two isocyanate groups have commensurate reactivity and the compound provides high mechanical properties. Preferably, a trifunctional or higher polyfunctional isocyanate is used simultaneously. Using a trifunctional or higher polyfunctional isocyanate here allows a branched structure to be introduced into the polyurethane, and is effective in further suppressing hard segment aggregation. In addition, a denser cross-linked structure can be introduced into the polyurethane, so that the contact between the elastic portion and the component to be cleaned can be made more stable. As a result, it is possible to effectively suppress wiping streaks and uneven wiping in the component to be cleaned. Examples of trifunctional or higher polyfunctional isocyanates include at least one selected from the group consisting of triphenylmethane-4,4',4"-triisocyanate (TTI), tris(phenylisocyanate)phosphorothioate (TPTI) and polymeric MDI. Among the aforementioned, tris(phenylisocyanate)phosphorothioate (TPTI) and polymeric MDI can be more suitably used. These isocyanates have a methylene group or an ether group between multiple NCO groups, so that the distance between multiple urethane bonds can be appropriately maintained. Therefore, these isocyanates are advantageous in suppressing the aggregation of hard segments.

[0094] Polymer MDI is represented by the following chemical formulas (1-1) and (1-2). In chemical formula (1-2), n represents an integer equal to or greater than 2. The upper limit of n is not particularly limited, but, for example, is preferably 4 or less. Chemical formula (1-1) corresponds to the structure in which n is 1 in chemical formula (1-2).

[0095]

[0096] The content of the trifunctional or higher-functional isocyanate in the polyisocyanate is preferably from 0.5% by mass to 20.0% by mass, and more preferably from 1.0% by mass to 19.5% by mass.

[0097] Catalysts commonly used in the curing of polyurethane elastomers can be used as catalysts; examples include tertiary amine catalysts. Specific examples include the following: amino alcohols 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; as well as triethylenediamine, piperazine compounds, and triazine compounds. Metal organic acid salts such as potassium acetate and potassium octoate can also be used. Metal catalysts commonly used for urethanization, such as dibutyltin dilaurate, can also be used. The foregoing can be used alone or in combination of two or more.

[0098] The starting material constituting the elastic member may contain, in addition to polyurethane, a pigment, a plasticizer, a water-repellent, an antioxidant, an ultraviolet absorber, a light stabilizer, and the like, as needed.

[0099] In the elastic member, the angle of the front end side edge formed by the main surface and the top end face is not particularly limited, but is generally about 85 degrees to 95 degrees. In addition, in the present disclosure, the hardness of the elastic member preferably falls within the range of 65° to 90°. In the present disclosure, the hardness (IRHD) of the elastic member is a value measured using a Wallace microhardness tester from HW Wallace & Co Limited in accordance with the International Rubber Hardness Test M method. The International Rubber Hardness Test M method is specified in JIS K 6253-1997.

[0100] One method for adjusting the coefficient of variation of the area ratio of the white region to be within a predetermined range and adjusting the value obtained by subtracting HM2 from HM1 to be within a predetermined range includes forming a solidified region on the surface of the cleaning blade according to a known method.

[0101] Specific examples of such methods are described below, but are not intended to be limiting.

[0102] Preferably, the curing region of the elastic member includes a main surface and a top end surface that forms a front end side edge together with the main surface. The curing region may further include surfaces other than the above, namely, a surface opposite to the main surface and a surface on one side of the mounting support member ( Figure 2 In this case, the rigidity of both end surfaces of the elastic member can be improved, and the occurrence of rolling up of the cleaning blade can be further reduced.

[0103] The method for forming the cured region in the polyurethane contained in the elastic member is not particularly limited, and a known method such as a method relying on ultraviolet rays or a method involving applying a cured region forming material and curing it can be employed here.

[0104] Furthermore, the degree of curing may be appropriately selected so that the coefficient of variation of the area ratio of the white region is adjusted to be within a predetermined range and the value obtained by subtracting HM2 from HM1 is adjusted to be within a predetermined range.

[0105] As a specific example, a method including applying a curing region forming material and curing it will be explained next.

[0106] The cured region forming material may be used after being diluted with a diluting solvent as needed, and may be applied to the cured region by a known method such as dipping, spraying, dispenser coating, brushing, or roller coating.

[0107] Isocyanate compounds, etc., used below, can be used as the curing region-forming material. In this case, it is sufficient to fully impregnate the polyurethane contained in the elastic member with the curing region-forming material (e.g., isocyanate compound). Impregnation is facilitated by increasing the concentration of the curing region-forming material and reducing its viscosity, so that the curing region-forming material can be heated without dilution.

[0108] The degree of curing can be adjusted, for example, by the duration of impregnation or immersion, the heat treatment temperature and heat treatment time after impregnation or immersion, and / or the subsequent standing time.

[0109] An example of a method for forming a cured region will be explained below based on an example using an isocyanate compound as a cured region forming material. In some cases, the elastic member to which the cured region forming material is applied may be referred to as a "precursor."

[0110] As described above, after applying the solidification region-forming material to the solidification region, the precursor may be heat-treated. The temperature of the solidification region-forming material may be set within a range of approximately 60°C to 80°C. The impregnation or immersion time cannot be specified in a single rule, but is preferably within a range of approximately 10 seconds to 60 seconds.

[0111] Due to the above-mentioned heat treatment, the viscosity of the cured region-forming material present on the surface of the polyurethane is reduced, thereby promoting both the penetration and diffusion of the material into the polyurethane.

[0112] The heating method is not particularly limited and may be a method comprising passing the precursor through a heating furnace or a method comprising blowing a hot air flow onto the precursor. The heating furnace includes, for example, a radiation heating furnace and a circulating air heating furnace, and the device for forming the hot air flow includes a hot air blower and a far-infrared heater.

[0113] By setting the heating conditions to a high temperature and / or a long heating time, the cured area becomes wider, which translates into higher elasticity. In preferred heating conditions, the surface temperature of the treated surface is set to, for example, within a range of 90°C to 110°C. Preferably, the heating time is set to, for example, within a range of 10 minutes to 30 minutes.

[0114] Furthermore, the amount of residual isocyanate during polyurethane formation tends to decrease gradually over time after formation. Therefore, although not limited thereto, the cured region can be formed immediately after the polyurethane is formed. For example, the cured region can be formed within 3 hours after the polyurethane is formed. The amount of residual isocyanate can also be adjusted based on the mixing ratio of the composition used during polyurethane formation.

[0115] The cured region forming material is not particularly limited as long as it cures polyurethane and forms a cured region on the surface of the polyurethane.

[0116] Examples of such materials include isocyanate compounds and acrylic compounds. The cured region-forming material may be used after being diluted with a solvent or the like. The solvent used for dilution is not particularly limited as long as it dissolves the material used, and examples include toluene, xylene, butyl acetate, methyl isobutyl ketone, and methyl ethyl ketone.

[0117] In the case where the polyurethane constituent material is a polyurethane elastomer, an isocyanate compound as a constituent material of the polyurethane elastomer may be used as a material for forming the cured region in terms of compatibility with the polyurethane and impregnation into the polyurethane.

[0118] An isocyanate compound having one or more isocyanate groups in its molecule can be used as the isocyanate compound to be brought into contact with the polyurethane.

[0119] Examples of the isocyanate compound having one isocyanate group in the molecule include aliphatic monoisocyanates such as octadecyl isocyanate (ODI) and aromatic monoisocyanates such as phenyl isocyanate (PHI).

[0120] As the isocyanate compound having two isocyanate groups in the molecule, compounds generally used for production of polyurethane resins can be used; examples of such compounds include the following.

[0121] 2,4-Toluene diisocyanate (2,4-TDI), 2,6-Toluene diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (MDI), metaphenylene diisocyanate (MPDI), tetramethylene diisocyanate (TMDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI).

[0122] For example, 4,4′,4″-triphenylmethane triisocyanate, 2,4,4′-biphenyl triisocyanate, or 2,4,4′-diphenylmethane triisocyanate can be used as the isocyanate compound having three or more isocyanate groups in the molecule.

[0123] Isocyanate compounds having two or more isocyanate groups in the molecule may also be used in the form of modified derivatives or polymers thereof. Here, MDI exhibiting high crystallinity (i.e., a symmetrical structure) is preferred in order to effectively increase the hardness of the cured region; in terms of processability, MDI including modified products is more preferred because MDI is, after all, liquid at room temperature.

[0124] Normally, a portion resulting from impregnation of polyurethane with isocyanate and curing and a portion resulting from curing of isocyanate or the like on the surface of polyurethane coexist in the cured region.

[0125] The production method of the cleaning blade is not particularly limited and can be selected from known appropriate methods. As the production method of the elastic member, a suitable method can be selected from known methods such as die forming and centrifugal forming.

[0126] For example, a supporting member to which an adhesive is applied at a region in contact with an elastic member is arranged in a mold for forming a cleaning blade provided with a cavity for forming the elastic member.

[0127] At the same time, a prepolymer obtained by partially polymerizing polyisocyanate and polyol is added to a curing agent, chain extender, catalyst and other additives containing polyol and loaded into a casting machine. The aforementioned substances are mixed and stirred at a constant ratio using a mixing chamber or the like to obtain a starting material composition such as a polyurethane elastomer. The starting material composition is injected into the above-mentioned mold to form a cured molded product (elastic member) on the surface of the supporting member coated with the adhesive, and demolded after the reaction and curing. Depending on the situation, it may be necessary to appropriately cut the elastic member in order to ensure the predetermined size of the elastic member and the predetermined edge size accuracy of the contact area of ​​the elastic member; thereby, a cleaning blade precursor in which the supporting member and the elastic member are integrally formed with each other can be produced.

[0128] In another method, two adhesive-coated support members are positioned facing each other in the mold cavity, whereupon the starting material composition is injected into the mold through openings at their longitudinal end faces. A curing reaction is then performed at 100°C to 150°C to produce a molded article in which the two support members are integrated via a polyurethane elastomer. In another method, the polyurethane portion of the molded article is then divided into two pieces by cutting along its center portion in the transverse direction. The polyurethane portion is further cut along both ends of the holder in the longitudinal direction, thereby producing two cleaning blades.

[0129] When injecting the starting material composition into the mold cavity, the mold is preferably tilted at an angle of 5° to 20° so that the starting material composition flows first over one of the two support members. By setting the tilt angle within the above range, air is less likely to be trapped between the two scrapers. Furthermore, due to the slow flow of the starting material composition during injection, the starting material composition can be prevented from solidifying before reaching the end of the cavity. Furthermore, by setting the tilt angle of the tilted mold to 0° before completing injection of the starting material composition into the mold, filling time can be shortened and underfilling can be further suppressed.

[0130] When producing an elastic member using a centrifugal forming machine, a prepolymer obtained by partially polymerizing a polyisocyanate and a polyol is mixed with a curing agent containing the polyol, a chain extender, a catalyst, and other additives, and stirred to obtain a starting material composition. The starting material composition is loaded into a rotating drum to obtain a polyurethane elastomer sheet. The polyurethane elastomer sheet is cut to ensure the predetermined size and the predetermined edge dimensional accuracy of the contact area 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.

[0131] The cured region can be formed using the method explained above. Specifically, a cured region-forming material is first applied to the main surface and the top surface of the elastic member of the cleaning blade precursor. The coated portion is then heat-treated, for example, at a temperature of 90°C or higher for 10 minutes or longer. This results in the formation of a cured region on the surface and within the coated portion.

[0132] In the case where the elastic member needs to be cut to form the leading edge of the cleaning blade, the solidified region can be formed before or after such cutting. In the case of centrifugal forming, the solidified region can be formed before attachment to the supporting member. Thus, a cleaning blade can be obtained as described above.

[0133] <Process Cartridge and Electrophotographic Image Forming Apparatus>

[0134] The cleaning blade according to the present disclosure can be used by being built into a process cartridge for an electrophotographic image forming apparatus. The process cartridge according to the present disclosure is a process cartridge having the cleaning blade for electrophotography according to the present disclosure.

[0135] The foregoing can be used by being built into an electrophotographic image forming apparatus.The electrophotographic image forming apparatus according to the present disclosure is an electrophotographic image forming apparatus having the electrophotographic cleaning blade according to the present disclosure.

[0136] [Example]

[0137] The present disclosure will be explained below by production examples, embodiments and comparative examples, but the present disclosure is by no means limited to these examples. As starting materials other than those listed in the examples and comparative examples, reagents or industrial chemicals are also used. Unless otherwise stated, the wording "parts" in the examples and comparative examples refers to mass basis throughout.

[0138] <Measurement and Calculation Methods for Area Ratios M1 to M100, Average Area Ratio AM, Standard Deviation Σ of Area Ratios, and Coefficient of Variation (100×Σ / AM)>

[0139] The measurements were performed using a scanning probe microscope (hereinafter referred to as SPM), and the calculations were performed according to the following method.

[0140] The scanning probe microscope (SPM) used herein was MFP-3D Origin (from Oxford Instruments plc).

[0141] The measurement sample preparation method is as follows.

[0142] Assume that a first line segment is drawn on the top surface of the cleaning blade parallel to the front end side edge and 10 μm away from the front end side edge, the length of the first line segment is defined as L, and the point on the first line segment that is 1 / 2L away from one end side is defined as P1, and a 2 mm square measurement sample is cut out with the center of gravity of the top surface at P1 and one side parallel to the first line segment. A 100 μm square polyurethane sheet with the center of gravity at P1 is cut out from the above measurement sample at -50°C using a freezing microtome (UC-6 (product name), from Leica Microsystems GmbH), one side of which is parallel to the first line segment and has a thickness of 1 μm. Thus, a measurement sample is prepared. The obtained measurement sample is placed on a smooth silicon wafer and allowed to stand for 24 hours in an environment at room temperature of 25°C and humidity of 50%.

[0143] Next, the silicon wafer with the measurement sample placed on it was placed on the SPM stage and SPM observation was performed. The spring constant and proportionality constant of the silicon cantilever (product name: OMCL-AC160, from Olympus Corporation, tip curvature radius: 8 nm) were previously determined using the SPM apparatus using the thermal noise method and were as follows: spring constant: 30.22 nN / nm, proportionality constant: 82.59 nm / V.

[0144] The cantilever was pre-tuned and the resonant frequencies of the cantilever were determined (285 KHz (first order) and 1.60 MHz (higher order)).

[0145] The measurement mode of SPM is the AM-FM viscoelastic mapping mode. The free amplitude of the cantilever is set to 3 V (first order) and 25 mV (high order), the set point amplitude is set to 2 V (first order), and a square (20 μm × 20 μm) area with a center of gravity at P1, a side length of 20 μm, and one side parallel to the first line segment is scanned under the conditions of a scanning speed of 1 Hz and 256 vertical scanning points and 256 horizontal scanning points, thereby obtaining a grayscale phase image of 256 gray levels as the viscoelastic image of the above-mentioned area.

[0146] The obtained phase image was binarized using an image processing analysis system (product name: Luzex-AP, from Nireco Corporation). Specifically, in the brightness frequency distribution obtained from the phase image, the threshold was set at the 93rd grayscale from the lowest grayscale side, and a binary image was created in which the portion above the threshold was depicted in black and the portion below the threshold was depicted in white. The binary image was further divided into 100 partitions (M1 to M100), each of which was a square with a side length of 2 μm, and the area ratio of the white area (M1 to M100), 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 in each partition (M1 to M100) were calculated, and the coefficient of variation of the area ratio of the white area (100×Σ / AM: unit "%") was further calculated.

[0147] <Measuring method of Martens hardness>

[0148] The Martens hardness was measured according to the following method.

[0149] Assume that a first line segment is drawn on the top end surface of the cleaning blade parallel to the front end side edge and 10 μm away from the front end side edge, the length of the first line segment is defined as L, and the point on the first line segment that is 1 / 2L away from one end side is defined as P1, and HM1 is defined as the Martens hardness of the elastic member measured at the position of P1.

[0150] At the same time, assuming that a bisector of the angle formed by the main surface and the top end surface is drawn on a cross section of the elastic member perpendicular to the top end surface and the front end side edge containing P1, HM2 is defined as the Martens hardness of the elastic member measured at a position 500 μm away from the front end side edge on the bisector.

[0151] Microhardness tester: Model DUH-211S, from Shimadzu Corporation

[0152] Measurement environment: temperature 23±5℃

[0153] Measuring indenter: triangular pyramid indenter 115° (ridge angle 115°)

[0154] Measurement Mode: Depth Setting Test

[0155] Depth setting: 2μm

[0156] Loading rate: 0.03mN / s

[0157] Hold time: 5 seconds

[0158] Calculation expression: Martens hardness = 1000F / 26.43h 2 (N / mm 2 )

[0159] F: test force (mN), h: indentation depth (μm)

[0160] In this example, the Figure 1 The cleaning blade shown is of an integrally formed type.

[0161] [Example 1]

[0162] <Supporting member>

[0163] A galvanized steel sheet with a thickness of 1.6 mm was prepared and processed to obtain a support member having an L-shaped cross section. Figure 2 Indicated by reference numeral 3. A polyurethane-metal single-layer adhesive (product name: Chemlock 219, from LORD Corporation) was applied to the portion of the support member that was in contact with the elastic member.

[0164] <Preparation of Raw Materials for Elastic Members>

[0165] The materials given in Table 1 below were mixed and reacted at a temperature of 80° C. for 3 hours to obtain a prepolymer having an NCO content of 10.0% by mass.

[0166] [Table 1]

[0167] Table 1

[0168]

[0169] The curing agent was prepared by mixing the materials shown in Table 2 below.

[0170] [Table 2]

[0171] Table 2

[0172]

[0173] A raw material composition for a polyurethane elastomer is prepared by mixing the above prepolymer and the above curing agent.

[0174] The support member, prepared above and to which the adhesive had been applied, was positioned so as to protrude into the cavity of the cleaning blade mold. The raw material composition was then injected into the cleaning blade mold and cured at 130°C for 2 minutes. The mold was then demolded to produce an integrally formed body of the polyurethane elastomer and the support member. Prior to molding, the cleaning blade mold was pre-coated with release agent A. Release agent A was a mixture of the materials listed in Table 3.

[0175] [Table 3]

[0176] Table 3

[0177]

[0178] The front end of the integrally molded polyurethane elastomer was cut to produce a plate-shaped elastic member having a main surface and a top end surface that, together with the main surface, formed a front end edge. The angle of the front end edge was 90 degrees, and the elastic member had a transverse length of 7.5 mm, a thickness length of 1.8 mm, and a length of 240 mm.

[0179] <Formation of Cured Region>

[0180] Carbodiimide-modified MDI (product name: Millionate MTL, from Tosoh Corporation) was used as a material for forming the cured region.

[0181] The five surfaces of the elastic member (excluding the surface on which the supporting member is mounted) ( Figure 2 The elastic member (see reference numeral 11 in the figure) was immersed in a cured region-forming material heated to 70°C for 20 seconds to apply the cured region-forming material to the corresponding surface. The time elapsed from the completion of molding of the elastic member until the formation of the cured region began (hereinafter also referred to as "standing time") was set to 1 hour.

[0182] The cured region-forming material was then wiped off the surface of the elastic member using a sponge soaked in butyl acetate as a solvent. Next, the elastic member was heat-treated in an electric furnace at 100°C for 10 minutes to diffuse the cured region-forming material impregnating the elastic member into the interior of the elastic member and solidify. Thus, a cleaning blade 1 was obtained in which cured regions were formed on five surfaces of the elastic member (the main surface, the top surface, the surface opposite the main surface, and both longitudinal end surfaces) and within the interior of the elastic member beneath these surfaces.

[0183] The obtained cleaning blades were evaluated according to the following methods. Table 4 shows the results of various evaluations.

[0184] [Evaluation 1] Average value AM of the area ratio of the white area and coefficient of variation of the area ratio of the white area

[0185] The area ratios M1 to M100 of the white areas relative to the surface area of ​​each subarea (M1 to M100) were calculated. The average AM and standard deviation Σ of the white area ratios were calculated using the above-described measurement and calculation methods. The coefficient of variation of the white area ratios was calculated from these results as (100 × Σ / AM; unit: "%).

[0186] [Evaluation 2] Poor Martens hardness

[0187] Here, the Martens hardness difference is obtained according to the above-mentioned measurement method.

[0188] [Evaluation 3] Evaluation of the performance of the cleaning blade

[0189] <Production of Toner 1>

[0190] (Step of preparing aqueous medium 1)

[0191] Here, in a reaction vessel equipped with a stirrer, a thermometer and a reflux tube, 14.0 parts of sodium phosphate (dodecahydrate, from Rasa Industries, Ltd.) were added to 650.0 parts of ion-exchanged water, and the whole was maintained at 65° C. for 1.0 hour while purging with nitrogen.

[0192] A TK homomixer (Tokushu Kika Kogyo Co., Ltd.) was used to add a calcium chloride aqueous solution obtained by dissolving 9.2 parts of calcium chloride (dihydrate) in 10.0 parts of ion-exchanged water all at once under stirring at 15,000 rpm to prepare an aqueous medium containing a dispersion stabilizer. Then, 10% by mass of hydrochloric acid was introduced into the aqueous medium to adjust the pH to 5.0, thereby obtaining an aqueous medium 1.

[0193] (Step of Preparing Polymerizable Monomer Composition)

[0194] -Styrene: 60.0 parts

[0195] -CI Pigment Blue 15:3: 6.5 parts

[0196] The above materials were charged into an attritor (from Mitsui Miike Machinery Co., Ltd.) and further dispersed at 220 rpm for 5.0 hours using zirconium oxide particles having a diameter of 1.7 mm to prepare a pigment dispersion. The following materials were added to the pigment dispersion.

[0197] -Styrene: 20.0 parts

[0198] - n-Butyl acrylate: 20.0 parts

[0199] - Cross-linking agent (divinylbenzene): 0.3 parts

[0200] -Saturated polyester resin: 5.0 parts

[0201] (Polycondensate 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)

[0202] -Fischer-Tropsch wax (melting point 78°C): 7.0 parts

[0203] The resulting product was maintained at 65° C. and dissolved and dispersed to uniformity at 500 rpm using a TK homomixer (from Tokushu Kika Kogyo Co., Ltd.) to prepare a polymerizable monomer composition.

[0204] (Granulation step)

[0205] While maintaining the temperature of aqueous medium 1 at 70°C and the rotation speed of the TK homomixer at 15,000 rpm, the polymerizable monomer composition was introduced into aqueous medium 1, and 10.0 parts of t-butyl peroxypivalate as a polymerization initiator was added. The entire mixture was then granulated in a stirring apparatus while maintaining the rotation speed at 15,000 rpm for 10 minutes.

[0206] (Polymerization / Distillation Step)

[0207] After the granulation step, the stirrer was replaced by a propeller stirring blade, and polymerization was performed for 5.0 hours while the temperature was maintained at 70° C. and stirred at 150 rpm; polymerization was then performed by increasing the temperature to 85° C. and heating for 2.0 hours.

[0208] Thereafter, the reflux tube of the reaction vessel was replaced with a cooling tube, and the resulting slurry was heated to 100° C. and distilled for 6 hours to distill off unreacted polymerizable monomers and obtain a toner base particle dispersion.

[0209] (Polymerization of Organosilicon Compounds)

[0210] Here, 60.0 parts of ion-exchanged water were weighed into a reaction container equipped with a stirrer and a thermometer, and the pH was adjusted to 4.0 using 10% by mass hydrochloric acid. The temperature was raised to 40° C. by heating under stirring.

[0211] 40.0 parts of methyltriethoxysilane as an organosilicon compound was then added thereto and stirred for at least 2 hours to cause hydrolysis. The end point of the hydrolysis was visually confirmed at the point when oil-water separation ceased and a single layer was formed; the hydrolyzed solution of the organosilicon compound was then obtained by cooling.

[0212] The temperature of the resulting toner base particle dispersion was lowered to 55°C, after which 25.0 parts of the hydrolyzed solution of the organosilicon compound was added to initiate polymerization of the organosilicon compound. After maintaining the solution as is for 15 minutes, the pH was adjusted to 5.5 using a 3.0% by mass aqueous sodium bicarbonate solution. The product was maintained at 55°C with stirring for 60 minutes, then adjusted to a pH of 9.5 using a 3.0% by mass aqueous sodium bicarbonate solution and maintained for a further 240 minutes to obtain a toner particle dispersion.

[0213] (Washing and drying steps)

[0214] Once the polymerization step is complete, the toner particle dispersion is cooled, and hydrochloric acid is added to the toner particle dispersion to adjust the pH to below 1.5. The dispersion is then allowed to stand with stirring for one hour, followed by solid-liquid separation using a pressure filter to obtain a toner cake. The toner cake is re-slurried with ion-exchanged water to form a dispersion again, and then subjected to solid-liquid separation using the aforementioned filter to obtain a toner cake.

[0215] The obtained toner cake was dried in a constant temperature bath at 40° C. for 72 hours and classified to obtain Toner 1.

[0216] <Evaluation of Cleaning Performance>

[0217] As a cleaning blade for a photosensitive drum as a member to be cleaned, a cleaning blade 1 was built into a cyan cartridge of a color laser printer (product name: HP LaserJet Enterprise Color M553dn, from The Hewlett-Packard Company).

[0218] The toner in the developer of the cyan cartridge was completely replaced with the above-mentioned toner 1.

[0219] Then, in a low-temperature, low-humidity environment (temperature 15° C., relative humidity 10%), 12,500 images were formed as the number of printable sheets (hereinafter referred to as “normal evaluation”).

[0220] In the developing machine used, the toner was then replaced with a new cyan cartridge in which all the toner was replaced with Toner 1; then, 12,500 images were formed again as the number of printable sheets (hereinafter referred to as "2-fold evaluation").

[0221] A hole was opened on the back of the cartridge, and the evaluation was performed while the waste toner was appropriately sucked out. The obtained images were evaluated according to the following criteria.

[0222] Rank A: Image defects (streaks on images) caused by the cleaning blade did not appear in either the normal evaluation or the 2-fold evaluation.

[0223] Rank B: Image defects (streaks on the image) caused by the cleaning blade did not appear in the normal evaluation, but slightly appeared in the 2x evaluation (streak length was 5 mm or less).

[0224] Rank C: Image defects (streaks on the image) caused by the cleaning blade did not appear in the normal evaluation, but appeared in the 2x evaluation (streak length exceeded 5 mm, up to 10 mm).

[0225] Rank D: An image defect (streak on the image) caused by the cleaning blade did not appear in the normal evaluation but appeared in the 2-fold evaluation (exceeding 10 mm).

[0226] Rank E: Image defects (streaks on images) caused by the cleaning blade occurred in both the normal evaluation and the 2-fold evaluation.

[0227] The evaluation was performed in the same manner as the above evaluation except that the rotation speed of the photosensitive drum in the above evaluation was modified from 170 rpm to 300 rpm.

[0228] [Evaluation 4] Evaluation of cleaning blade curling

[0229] In the above-mentioned evaluation of cleaning performance, no curling or abnormal sound occurred.

[0230] In Evaluation 4, under high-speed processing conditions and during long-term use, the curling of the cleaning blade was evaluated as follows.

[0231] A cleaning blade 1 was installed in a new cyan cartridge, different from the one used for the cleaning performance evaluation, as a cleaning blade for the photosensitive drum being cleaned. The toner in the developer of the cyan cartridge was completely replaced with the aforementioned toner 1. 15,000 images were then formed in a low-temperature environment (0°C).

[0232] Afterwards, the cartridge removed from the developer was placed in an idling rotary machine (equipped with a fixture for holding the cartridge while rotating the photosensitive drum). The photosensitive drum was idling at a speed of 170 rpm under the same conditions, and the state of the leading end of the cleaning blade was observed for more than 10 minutes. This observation was performed while the cartridge was being processed and the CCD camera was installed. Evaluation was performed according to the following criteria.

[0233] Rank A: No curling or abnormal sound (chattering sound) occurs.

[0234] Grade B: No curling occurred, but an abnormal sound (chattering sound) slightly occurred.

[0235] Grade C: No curling occurred, but an abnormal sound (chattering sound) occurred.

[0236] D-Class: Roll-up occurs.

[0237] The evaluation was performed in the same manner as the above evaluation except that the rotation speed of the photosensitive drum in the above evaluation was modified from 170 rpm to 300 rpm.

[0238] [Examples 2 to 12]

[0239] Cleaning blades 2 to 12 were obtained in the same manner as in Example 1, except that the temperature, immersion time, heat treatment temperature, heat treatment time, and standing time (the time elapsed from the molding of the elastic member until the formation of the solidified region) of the solidified region forming material involved in the solidified region formation were modified to the conditions given in Table 4.

[0240] [Example 13]

[0241] The cleaning blade according to the present embodiment was produced in the same manner as in Example 1, except that the curing region was only imparted to the top face. Specifically, the curing region forming material used in Example 1 was heated to a temperature of 80°C and applied to the top face of the elastic member using a dispenser. The standing time from the completion of the forming of the elastic member until the start of the formation of the curing region was set to 1 hour. Once the application of the curing region forming material was completed, the integrally formed body was allowed to stand in an environment with a temperature of 25°C and a relative humidity of 50% for 10 minutes. Then, the integrally formed body was heat-treated in an electric furnace at a temperature of 100°C for 10 minutes so that the curing region forming material with which the elastic member was impregnated diffused into the interior of the elastic member and became cured. Thus, the cleaning blade 13 according to the present embodiment was obtained.

[0242] Table 4 lists the evaluation results of the cleaning blades according to Examples 1 to 13.

[0243] [Table 4]

[0244] Table 4

[0245]

[0246]

[0247] [Comparative Example 1]

[0248] A cleaning blade H1 according to this comparative example was produced in the same manner as in Example 1, except that no cured region was formed here.

[0249] [Comparative Example 2]

[0250] <Preparation of Raw Materials for Elastic Members>

[0251] The materials given in Table 5 below were reacted at 80° C. for 3 hours under stirring to obtain a prepolymer having an NCO content of 8.50%.

[0252] [Table 5]

[0253] Table 5

[0254]

[0255] The curing agent was prepared by mixing the materials shown in Table 6 below.

[0256] [Table 6]

[0257] Table 6

[0258]

[0259] By mixing the above prepolymer and the above mixture, a raw material composition for a polyurethane elastomer was obtained. 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.

[0260] [Comparative Example 3]

[0261] A cleaning blade H3 was obtained in the same manner as in Comparative Example 2, except that the temperature of the curing region forming material, the immersion time, and the heat treatment temperature, heat treatment time, and placement time (the time elapsed from the forming of the elastic member until the curing region is formed) involved in the curing region formation were modified to the conditions given in Table 7.

[0262] Table 7 lists the evaluation results of the cleaning blades according to Comparative Examples 1 to 3.

[0263] [Table 7]

[0264] Table 7

[0265]

[0266] The present disclosure is not limited to the above embodiments, and various modifications and variations can be adapted without departing from the spirit and scope of the present disclosure. Therefore, for the purpose of disclosing the scope of the present disclosure, the following claims are attached.

[0267] This application claims the benefit of Japanese Patent Application No. 2020-186348, filed November 9, 2020, which is hereby incorporated by reference herein in its entirety.

[0268] Description of Reference Numerals

[0269] 1 Cleaning scraper

[0270] 2 elastic member

[0271] 3 Supporting components

[0272] 4 front end

[0273] 5 Main Surfaces

[0274] 6 Top surface

[0275] 7Front end side edge

[0276] 8 components to be cleaned

[0277] 10 Surface opposite to the main surface

[0278] 11 Surface on the side where the support member is mounted

[0279] R Rotation direction of the component being cleaned

Claims

1. A cleaning blade for electrophotography, characterized in that It includes: an elastic member comprising polyurethane; and a supporting member that supports the elastic member, and The surface of the member to be cleaned is cleaned by causing a portion of the elastic member to contact the surface of the member to be cleaned while moving, wherein When the side of the cleaning blade that contacts the surface of the member to be cleaned is defined as the front end side of the cleaning blade, The elastic member has a plate shape at least on the front end side, the plate shape having a main surface facing the member to be cleaned and a top end surface forming a front end side edge together with the main surface; Assume that a first line segment is drawn on the top end surface in parallel with the front end side edge and is 10 μm away from the front end side edge. where the length of the first line segment is denoted by L, and The point on the first line segment that is 1 / 2L away from one end side is represented by P1; When a square area of ​​the top surface is scanned by using a scanning probe microscope under conditions involving a scanning speed of 1 Hz and 256 vertical scanning points and 256 horizontal scanning points to acquire a grayscale phase image of 256 grayscale levels as a viscoelastic image of the area, the square area has a center of gravity at P1, has a side length of 20 μm, and has one side parallel to the first line segment, In the brightness frequency distribution obtained from the phase image, a binarized image is created with a threshold at the 93rd grayscale from the lowest grayscale side so that a portion above the threshold is depicted in black and a portion below the threshold is depicted in white, the binarized image is divided into 100 sections each being a square with a side length of 2 μm, and When the coefficient of variation of the area ratio of the white area is obtained based on the area ratio of the white area in each partition, 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 less than 20.00; and Assuming that a line bisecting the angle formed by the main surface and the top end surface is drawn on a cross section of the elastic member perpendicular to the top end surface P1 and the front end side edge, The value obtained by subtracting the Martens hardness HM2 of the elastic member measured at a position 500 μm away from the front end side edge on the bisector from the Martens hardness HM1 of the elastic member measured at the position P1 is greater than 0.10 N / mm 2 .

2. The electrophotographic cleaning blade according to claim 1, wherein The average value AM of the area ratio of the white region is 45.0% or more.

3. The electrophotographic cleaning blade according to claim 1 or 2, wherein The polyurethane includes a reaction product of a composition including an isocyanate compound including a trifunctional or higher polyfunctional isocyanate.

4. The electrophotographic cleaning blade according to claim 3, wherein The polyurethane includes a reaction product of a composition including an isocyanate compound including a diisocyanate and a tri- or higher-functional polyfunctional isocyanate and an alcohol including a tri- or higher-functional polyfunctional alcohol.

5. A processing cartridge, characterized in that: The cleaning blade for electrophotography comprises the cleaning blade according to any one of claims 1 to 4.

6. An electrophotographic image forming apparatus, characterized in that The cleaning blade for electrophotography comprises the cleaning blade according to any one of claims 1 to 4.

Images