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

Abstract

Provided is a cleaning blade capable of stably exhibiting excellent cleaning performance over a long period of time. The electrophotographic cleaning blade includes an elastic member including polyurethane and a support member for supporting the elastic member, a portion of the elastic member is brought into contact with a surface of a movable member to be cleaned, and the surface of the member to be cleaned is cleaned. In an environment of 8 DEG C, when a storage elastic modulus of the elastic member at a vibration frequency of 1 * 10 <-3 > Hz is represented by E '(1), and when a storage elastic modulus of the elastic member at a vibration frequency of 1 * 10 < 4 > Hz is represented by E' (2), E '(1) is 12.0 to 18.0 MPa and E' (2) is 530.0 to 1500.0 MPa.

Description

Technical Field

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

[0002] In an electrophotographic image forming apparatus (hereinafter also referred to as an electrophotographic apparatus), some are equipped with a cleaning member to remove toner remaining on the surfaces of an electrostatic latent image bearing member such as a photoreceptor and an intermediate transfer member even after the toner image is transferred from the electrostatic latent image bearing member or the intermediate transfer member to a transfer body. One such cleaning member is an electrophotographic cleaning blade (hereinafter also simply referred to as a cleaning blade). Hereinafter, a member whose surface is cleaned by bringing the cleaning blade into contact therewith, such as an electrostatic latent image bearing member or an intermediate transfer member, may be referred to as a member to be cleaned.

[0003] In recent years, as the life of electrophotographic apparatuses has become longer, it has been required that the cleaning blade exhibits stable and excellent cleaning performance over a long period of time.

[0004] The applicant of the present application has disclosed in Patent Document 1 an electrophotographic cleaning blade provided with an elastic member containing polyurethane, which has excellent crack resistance and can stably exhibit excellent cleaning performance.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-092756

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2018-004857 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] The present inventors further studied the electrophotographic cleaning blade according to Patent Document 1. In the process, problems to be solved by the electrophotographic cleaning blade were found. The electrophotographic cleaning blade is formed using polymeric MDI as a raw material for polyurethane. This suppresses the aggregation of hard segments in the polyurethane and achieves excellent cleaning performance by finely dispersing the hard segments.

[0011] However, since the electrophotographic cleaning blade according to Patent Document 1 uses polymeric MDI as a raw material, it exhibits a relatively high elastic modulus when contacting a member to be cleaned in a stationary state of the cleaning blade. Therefore, when the cleaning blade contacts the member to be cleaned, the nip width tends to narrow to about several micrometers. The narrow nip width itself is advantageous for increasing the contact pressure of the cleaning blade against the member to be cleaned. However, it has been found that when scratches occur on the surface of the member to be cleaned that contacts the cleaning blade during the long-term use of the electrophotographic apparatus, the narrow nip width causes a problem of poor cleaning at the scratched portion.

[0012] At least one aspect of the present disclosure aims to provide a cleaning blade that can stably exhibit excellent cleaning performance over a long period of time.

[0013] In addition, at least one aspect of the present disclosure aims to provide a process cartridge that contributes to the formation of high-quality electrophotographic images.

[0014] In addition, at least one aspect of the present disclosure aims to provide an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images.

[0015] Solution to the problem

[0016] At least one aspect of the present disclosure aims to provide an electrophotographic cleaning blade including:

[0017] an elastic member containing polyurethane; and a support member that supports the elastic member,

[0018] The electrophotographic cleaning blade cleans the surface of the member to be cleaned by bringing a part of the elastic member into contact with the surface of the moving member to be cleaned, wherein

[0019] in an environment of 8 °C, when the storage elastic modulus of the elastic member at a vibration frequency of 1 × 10 -3 Hz is represented as E’(1) and the storage elastic modulus at a vibration frequency of 1 × 10 4 Hz is represented as E’(2), E’(1) is 12.0 to 18.0 MPa, and

[0020] E’(2) is 530.0 to 1500.0 MPa.

[0021] In addition, at least one aspect of the present disclosure aims to provide a process cartridge including the above electrophotographic cleaning blade. Further, at least one aspect of the present disclosure aims to provide an electrophotographic image forming apparatus including the above electrophotographic cleaning blade.

[0022] Advantageous effects of the invention

[0023] At least one aspect of the present disclosure may provide a cleaning blade that can stably exhibit excellent cleaning performance over a long period of time. In addition, at least one aspect of the present disclosure may provide a process cartridge that contributes to the formation of a high-quality electrophotographic image. In addition, at least one aspect of the present disclosure may provide an electrophotographic image forming apparatus that can stably form a high-quality electrophotographic image. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic perspective view of an electrophotographic cleaning blade according to one aspect of the present disclosure.

[0025] Figure 2 Diagram showing a state where the edge of the cleaning blade contacts the member to be cleaned when the process cartridge is stationary.

[0026] Figure 3 Diagram showing a method of measuring the nip width.

[0027] Figure 4 Diagram showing a method of measuring stick-slip.

[0028] Figure 5 Overall curve showing the relationship between the storage elastic modulus and the measurement frequency of the elastic members according to Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0029] In the present disclosure, unless otherwise specified, the expression "from XX to (~) YY" or "XX to (~) YY" indicating a numerical range means a numerical range including the lower limit and the upper limit as endpoints. When describing a numerical range in a stepwise manner, the upper limit and the lower limit of each numerical range can be arbitrarily combined.

[0030] In addition, in the present disclosure, for example, the description "at least one selected from the group consisting of XX, YY, and ZZ" means any one of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, and a combination of XX, YY, and ZZ.

[0031] The present inventors conducted research with the aim of obtaining a cleaning blade that can stably exhibit excellent cleaning performance even when scratches occur on the surface of the member to be cleaned during long-term use.

[0032] ​​​​​In this process, the inventors of the present invention considered reducing the elastic modulus of the elastic member to increase the nip width with the member to be cleaned and to stabilize the contact between the cleaning blade and the member to be cleaned. At the same time, increasing the nip width reduces the contact pressure per unit area of the nip portion and reduces the cleaning performance. In addition, if the elastic modulus of the cleaning blade is reduced, so-called stick-slip may occur. Stick-slip means that the tip of the elastic member of the cleaning blade extends in the advancing direction of the member to be cleaned and then returns to its original shape by elasticity. When such stick-slip occurs, the toner and the external additive easily slide over the cleaning blade, and poor cleaning may occur.

[0033] Therefore, the inventors of the present invention conducted further research to achieve both a sufficient nip width and excellent cleaning performance at a higher level. As a result, regarding the storage elastic modulus of the elastic member of the cleaning blade at a specific vibration frequency in a low-temperature environment of 8°C, when the storage elastic modulus at a low frequency (1×10 -3 Hz) is denoted as E’(1) and the storage elastic modulus at a high frequency (1×10 4 Hz) is denoted as E’(2), the inventors found that E’(1) being 12.0 to 18.0 MPa and E’(2) being 530.0 to 1500.0 MPa effectively achieves both a sufficient nip width and excellent cleaning performance at a higher level.

[0034] E’(1) being in the range of 12.0 to 18.0 MPa indicates that the elastic member is soft enough in a stable state where the member to be cleaned and the cleaning blade are in static contact. This is sufficient to ensure the nip width between the elastic member of the cleaning blade and the member to be cleaned.

[0035] At the same time, E’(2) being in the range of 530.0 to 1500.0 MPa indicates that the elastic member is hard enough in a state where the member to be cleaned and the cleaning blade are in contact while moving relative to each other and vibration is applied to the elastic member. This improves the scraping property of the dirt on the surface of the member to be cleaned and suppresses stick-slip caused by the extension of the contact area of the elastic member with the member to be cleaned in the moving direction of the member to be cleaned.

[0036] In a conventional elastic member containing polyurethane, the storage elastic modulus also tends to increase as the vibration frequency increases. However, it is considered that an elastic member containing polyurethane that achieves both a storage elastic modulus at a sufficiently low low frequency and a storage elastic modulus at a sufficiently high high frequency as described above has not been known heretofore.

[0037] A cleaning blade according to one aspect of the present disclosure is described below.

[0038] An electrophotographic cleaning blade (hereinafter simply referred to as "cleaning blade") according to one aspect of the present disclosure is applicable to a member to be cleaned such as an image bearing member such as a photoreceptor and an endless belt such as an intermediate transfer belt. Hereinafter, embodiments of the cleaning blade according to one aspect of the present disclosure will be described in detail with reference to an image bearing member as an example of the member to be cleaned, but the present disclosure is not limited thereto. In the following description, members having the same function are denoted by the same reference numerals in the drawings, and the description thereof may be omitted.

[0039] <Configuration of the cleaning blade>

[0040] The cleaning blade includes an elastic member containing polyurethane and a support member that supports the elastic member, and cleans the surface of the member to be cleaned by bringing a part of the elastic member into contact with the surface of the moving member to be cleaned.

[0041] Figure 1 is a schematic perspective view of a cleaning blade 1 according to one aspect of the present disclosure. The cleaning blade 1 includes an elastic member 2 and a support member 3 that supports the elastic member 2.

[0042] Figure 2 is a cross-sectional view schematically showing an example of a state in which a cleaning blade according to one aspect of the present disclosure is in contact with a member to be cleaned. The elastic member 2 has a main surface 4 facing the member to be cleaned 6 and a front surface 5 that forms a front end side edge together with the main surface 4. Reference numeral 7 indicates the rotation direction of the member to be cleaned.

[0043] <Analysis of cleaning phenomenon, vibration and cleaning>

[0044] The present inventors have analyzed in detail the behavior of the contact area (the front end of the elastic member) of the elastic member with the contacted member when the cleaning blade contacts a stationary member and the behavior of the front end of the elastic member when the cleaning blade contacts a moving member. As a result, the present inventors have found that the nip width between the cleaning blade and the member to be cleaned and the cleaning performance are related to the storage elastic modulus of the elastic member at the following first and second vibration frequencies.

[0045] <Storage elastic modulus E’(1) at the first vibration frequency>

[0046] Regarding the nip width between the cleaning blade and the member to be cleaned, the storage elastic modulus of the elastic member of the cleaning blade is important when the vibration frequency is 1×10 -3 Hz (hereinafter also referred to as "first vibration frequency").

[0047] Since the cleaning blade remains in contact with the photoreceptor even during the non-operating state, the nip between the cleaning blade and the member to be cleaned is formed in a state where the stress is sufficiently relaxed.

[0048] The first vibration frequency related to the contact between the cleaning blade and the member to be cleaned in the steady state can be determined as follows. Bring the elastic member of the cleaning blade into contact with one surface of a transparent flat glass plate, and while moving the glass plate in a direction orthogonal to the length direction of the cleaning blade, observe the state of the nip from the other surface side of the flat glass plate using a laser microscope. At this time, it can be observed that as the time during which the flat glass plate and the cleaning blade are in contact with each other and remain so becomes longer, the nip width becomes wider. It can be observed that this nip diffusion converges at approximately 1×10 -3 Hz. Thus, it is considered that the vibration frequency related to the contact state between the cleaning blade and the member to be cleaned is 1×10 -3 Hz. Therefore, the storage elastic modulus at 1×10 -3 Hz affects the nip width.

[0049] The nip width is preferably 17 μm or more, more preferably 18 μm or more, and even more preferably 19 μm or more in order to prevent the toner and external additives from slipping through the nip portion at the location where a scratch occurs on the member to be cleaned. Additionally, from the viewpoint of ensuring the contact pressure of the cleaning blade against the member to be cleaned, the nip width is preferably 25 μm or less, particularly more preferably 24 μm or less, and even more preferably 23 μm or less. For example, the nip width can preferably be in the range of 17 to 25 μm, 19 to 24 μm, or 20 to 23 μm.

[0050] <Storage elastic modulus E’(2) at the second vibration frequency>

[0051] The vibration frequency (second vibration frequency) related to the stick-slip of the front end of the cleaning blade in contact with the member to be cleaned is 1×10 4 Hz.

[0052] The vibration frequency related to the stick-slip can be measured as follows.

[0053] In a state where the elastic member of the cleaning blade is in contact with the electrophotographic photosensitive drum as the member to be cleaned, while supplying a small amount of toner, rotate the electrophotographic photosensitive drum (rotation speed 150 rpm), and observe the movement of the front end of the contact area of the cleaning blade at this time using a laser displacement meter. As a result, displacement was observed at a period of 1×10 4 Hz. It is considered that this indicates that the stick-slip causes the front end of the cleaning blade to move at a period of 1×10 4 Hz. Therefore, it is considered that the storage elastic modulus at 1×10 4 Hz related to the stick-slip affects the stick-slip width.

[0054] When stick-slip occurs, toner or external additives present near the nip may not be scraped off and may slip out of the cleaning blade. Therefore, by reducing the amount of vibration of the cleaning blade due to stick-slip, the possibility that toner and external additives can slide past the cleaning blade can be reduced, and as a result, the cleaning performance can be improved.

[0055] Specifically, the stick-slip width measured under the conditions described in the [Stick-Slip Evaluation] of the following examples is preferably 20 μm or less, more preferably 17 μm or less, and even more preferably 15 μm or less. The smaller the stick-slip width, the more preferable, and the lower limit of the stick-slip width is not particularly limited. For example, the preferable stick-slip width can be 0 to 15 μm, 0 to 17 μm, or 0 to 20 μm.

[0056] <Dynamic Viscoelasticity and Cleaning>

[0057] As described above, the present inventors advanced the research by focusing on the frequency dependence of the dynamic viscoelasticity of the urethane material from the recognition that the vibration of the elastic member of the cleaning blade is closely related to the cleaning phenomenon.

[0058] For example, the present inventors found that a cleaning blade in the following aspects can exhibit excellent cleaning performance even in a long-life system.

[0059] Specifically, the elastic member has the following characteristics in an 8°C environment:

[0060] When the storage elastic modulus of the elastic member at a vibration frequency of 1×10 3 Hz is denoted as E’(1) and the storage elastic modulus of the elastic member at a vibration frequency of 1×10 4 Hz is denoted as E’(2), E’(1) is 12.0 to 18.0 MPa, and E’(2) is 530.0 to 1500.0 MPa.

[0061] The storage elastic modulus E’(1) of the elastic member at a vibration frequency of 1×10 -3 Hz affects the formation of an appropriate nip width. When E’(1) is 18.0 MPa or less, the elastic member is soft enough when the elastic member contacts the stationary member to be cleaned and forms a nip, and thus an appropriate nip width can be ensured. Therefore, contact can be maintained even during long-term use, and toner and external additives can be prevented from slipping past. When E’(2) is 12.0 MPa or more, an excessive increase in the nip width due to the elastic member being overly soft can be suppressed. As a result, the contact pressure of the cleaning blade on the member to be cleaned at the nip portion can be appropriately maintained.

[0062] E’(1) is more preferably 17.5 MPa or less and still more preferably 17.0 MPa or less. Additionally, it is more preferably 12.5 MPa or more and still more preferably 13.0 MPa or more. For example, preferably, a range of 12.5 to 17.5 MPa or 13.0 to 17.0 MPa can be mentioned.

[0063] The value of E’(1) can be controlled by the molecular mobility of the components constituting the elastic member. The specific control method will be described below.

[0064] The storage elastic modulus E’(2) of the elastic member at a vibration frequency of 1×10 4 Hz affects the suppression of stick-slip. When E’(2) is 530.0 MPa to 1500.0 MPa, it means that when the cleaning blade vibrates at 1×10 4 Hz, the tip of the elastic member of the cleaning blade is difficult to move, that is, the tip is difficult to extend in the moving direction of the member to be cleaned. As a result, stick-slip can be suppressed, and the slipping of the toner and the external additive can be suppressed.

[0065] From the viewpoint of suppressing stick-slip, E’(2) is preferably 750.0 MPa or more and more preferably 950.0 MPa or more. For example, E′(2) is preferably 750.0 to 1500.0 MPa and particularly preferably 950.0 to 1500.0 MPa.

[0066] The value of E’(2) can be controlled by the molecular mobility of the components constituting the elastic member. The specific control method will be described below.

[0067] The elastic member includes polyurethane. Polyurethane (specifically, polyurethane elastomer) is composed of, for example, hard segments and soft segments. In the present disclosure, the hard segment refers to a component having a small molecular mobility at or near the crosslinking point, such as cyanate bonds, polymeric MDI, trimethylolpropane, or an aggregated crystal component of urethane bonds, etc. The soft segment refers to a segment having a large molecular mobility between the crosslinking points.

[0068] The elastic modulus in the low-frequency region such as E’(1) reflects the overall molecular mobility of the polyurethane molecules and is affected by both the molecular mobility of the hard segments and the molecular mobility of the soft segments.

[0069] In the low-frequency region, the soft segment, which is a component with high molecular mobility, can move freely due to a sufficient relaxation time and contributes little to the elastic modulus. However, the hard segment, which is a component with low molecular mobility, cannot move freely, and the magnitude of its molecular mobility contributes to the elastic modulus. That is, the greater the molecular mobility of the hard segment, the smaller E’(1), and the smaller the molecular mobility of the hard segment, the greater E’(1). Therefore, for the polyurethane in the elastic member according to one aspect of the present disclosure, it is important to increase the molecular mobility of the hard segment.

[0070] In contrast, in the high-frequency region, even the soft segment cannot move freely due to a short relaxation time, and the magnitude of its molecular mobility contributes to the elastic modulus. At the same time, the hard segment cannot move sufficiently. Therefore, when the soft segment can no longer move freely, the entire polymer freezes, and the elastic modulus increases rapidly. Therefore, in terms of the storage elastic modulus in the high-frequency region, the influence of the molecular mobility of the soft segment is more significant than that of the molecular mobility of the hard segment. That is, the greater the molecular mobility of the soft segment, the smaller E’(2), and the smaller the molecular mobility of the soft segment, the greater E’(2). Therefore, for the polyurethane in the elastic member according to one aspect of the present disclosure, it is important to decrease the molecular mobility of the soft segment.

[0071] As described above, E’(1) can be mainly controlled by adjusting the molecular mobility of the hard segment, and E′(2) can be mainly controlled by adjusting the molecular mobility of the soft segment.

[0072] The molecular mobility of the hard segment becomes smaller with an increase in rigid components such as cyanate ester bonds in polyurethane, crosslinked portions derived from polymeric MDI, or crystal structures formed by the interaction between soft segments, and becomes larger by making the crosslinking points softer.

[0073] Therefore, in order to decrease E’(1), it is preferable to use as little polymeric MDI as possible as a raw material for polyurethane, and it is particularly preferable not to use it at all. In order not to form crystal components due to the interaction of soft segments, it is preferable to use trimethylolpropane (TMP) as a crosslinking component. By introducing a crosslinked structure derived from TMP into the polyurethane, the soft segment portions present between the crosslinked structures are less likely to interact due to the steric hindrance of the crosslinked structure derived from TMP. As a result, crystal structures (crystal components), in other words, the formation of hard segments, are suppressed due to the interaction between the soft segments.

[0074] Since trimethylolpropane has a methylene skeleton adjacent to the hydroxyl group, a crosslinked structure with a soft molecular structure is formed. Therefore, the molecular mobility of the hard segment of the polyurethane according to one aspect of the present disclosure is higher than that of a polyurethane having a rigid crosslinked structure derived from polymeric MDI, which can decrease E’(1).

[0075] The molecular mobility of the soft segments can be controlled by the crosslinking density. The higher the crosslinking density, the smaller the molecular weight between crosslinking points and the smaller the space in which the soft segments can move freely. Therefore, the molecular mobility becomes smaller. To suppress the molecular mobility of the soft segments, it is also effective to make the lengths of the soft segments between crosslinking points uniform.

[0076] In addition, making the lengths of the soft segments uniform can make the increase in the storage elastic modulus in the total curve from the low-frequency range to the high-frequency range steeper. Thus, it is easier to obtain an elastic member with E’(1) in the range of 12.0 to 18.0 MPa and E’(2) in the range of 530.0 to 1500.0 MPa.

[0077] To obtain a polyurethane with short distances between crosslinking points and uniform lengths between crosslinking points, for example, it is preferable to control the number-average molecular weight of the prepolymer used as a raw material for the polyurethane within the range of 8000 to 12000 and to use as little chain extender as possible, such as 1,4-butanediol, and particularly preferably not to use any chain extender at all.

[0078] An example of the measurement conditions for the number-average molecular weight of the prepolymer is as follows.

[0079] Apparatus: HLC-8320GPC (trade name, manufactured by Tosoh Corporation)

[0080] Column: TSKgel SuperMultipore HZ-N (trade name, Tosoh Corporation; 4.6 mm ID × 15 cm)

[0081] Eluent: THF

[0082] Flow rate: 0.35 mL / min.

[0083] Sample: 0.5 wt% THF solution

[0084] Injection volume: 10 μL

[0085] Detector: RI

[0086] Temperature: 40 °C

[0087] Standard substance: Polystyrene

[0088] Specifically, by making the molecular mobility of the hard segments large and the molecular mobility of the soft segments small, an elastic member with a small E’(1) and a large E’(2) can be obtained. As a result, an elastic member that can achieve both the formation of an appropriate nip width and the suppression of stick-slip can be obtained, that is, an elastic member different from the conventional ones.

[0089] The elastic member of the cleaning blade according to Patent Document 1 uses polymeric MDI as a raw material for polyurethane in order to make the hard segments finer and more dispersed. As a result, the crosslinking points derived from polymeric MDI become rigid, and the molecular mobility of the hard segments decreases. Therefore, it is considered that the value of E’(1) is not small enough for the cleaning blade according to the present disclosure. Specific examples are shown in Comparative Example 1 described later. Therefore, it is considered that the cleaning blade according to Patent Document 1 is more likely to have a narrow nip width than the cleaning blade according to the present disclosure. Therefore, when used for a cleaning member with scratches, there is room for improvement in the cleaning performance of the cleaning blade according to Patent Document 1.

[0090] Although trimethylolpropane is used as a crosslinking component in the examples of the cleaning blade for an electrophotographic apparatus according to Patent Document 2, the addition amount is small. As a result, in the polyurethane according to Patent Document 2, it is considered that due to the aggregation of the soft segments, a crystal structure may be generated, and the value of the storage elastic modulus in the low-frequency region increases. In addition, Patent Document 2 discloses the use of a chain extender such as 1,4-butanediol as a raw material for polyurethane. Therefore, it is considered that the length between the crosslinking points of the soft segments is uneven. As a result, it is considered that since the total curve showing the relationship between the storage elastic modulus and the vibration frequency does not rise sharply, the storage elastic modulus in the high-frequency region is not high enough. Therefore, the cleaning blade for an electrophotographic apparatus according to Patent Document 2 may have a narrow nip width and may not be able to sufficiently suppress stick-slip.

[0091] As described above, ensuring the nip width and suppressing the stick-slip tendency are contradictory. In contrast, for the elastic member of the cleaning blade according to the present disclosure, by making E’(1) smaller and E’(2) larger, in other words, by making the total curve showing the relationship between the storage elastic modulus and the vibration frequency steeper, it is possible to suppress stick-slip while forming an appropriate nip width.

[0092] <Method for Measuring Storage Elastic Modulus>

[0093] E’(1) and E’(2) can be obtained by measuring the dynamic viscoelasticity of a sample under conditions of arbitrarily set frequency and temperature using a dynamic viscoelasticity device, and plotting a total curve from the measurement data at a reference temperature of 8°C.

[0094] The total curve is plotted based on the time-temperature equivalence principle. The horizontal axis represents the frequency, and the vertical axis represents the elastic modulus. The total curve can be plotted by shifting the frequency dispersion data measured at each temperature along the horizontal axis direction so as to overlap with the data at the reference temperature.

[0095] For example, the obtained total curve is curve-fitted and converted into a mathematical formula based on the generalized Maxwell model to calculate the storage elastic modulus E’(1) of the elastic member at 1×10 -3 Hz and the storage elastic modulus of the elastic member at 1×104 Storage elastic modulus E’(2) at

[0096] The reason for setting the temperature for measuring the storage elastic modulus at 8°C is that when using a printer in a low - temperature region such as 8°C, the toner is likely to be charged, and the adhesion of the toner to the photoreceptor increases, making cleaning more difficult.

[0097] The molecular mobility of the soft segment and the hard segment can be evaluated based on the spin - spin relaxation time T2 (transverse relaxation time) in pulsed NMR.

[0098] In the pulsed NMR measurement at 50°C, when divided into two components of the hard segment and the soft segment, the spin - spin relaxation time (T2 L ) of the soft segment is preferably 250 to 320 μs.

[0099] If the soft segment has high molecular mobility, the spin - spin relaxation time (T2 L ) is large because relaxation consumes time.

[0100] The spin - spin relaxation time T2 is measured by the solid - echo method using a pulsed NMR device.

[0101] The pulsed NMR device is a device for evaluating the mobility of polymer molecules such as rubber based on the mobility (relaxation time) of hydrogen atoms in the molecular chain. In this embodiment, the solid - echo method is used as the sequence. The solid - echo method using the pulsed NMR device itself can be a known method and is not particularly limited.

[0102] By measuring the spin - spin relaxation time T2 of the elastic member of the cleaning blade by pulsed NMR measurement, a T2 relaxation curve (free induction decay curve) is obtained.

[0103] Specific measurement means will be described below.

[0104] If T2 L is less than 250 μs, then E’(1) is likely to be large. In contrast, when T2 L exceeds 320 μs, E’(2) is likely to be small. T2 L being 250 to 320 μs helps E’(1) and E’(2) to satisfy the specific ranges mentioned above.

[0105] T2 L is more preferably 260 μs or more and still more preferably 270 μs or more. Additionally, it is more preferably 310 μs or less and still more preferably 300 μs or less. For example, it is preferably in the range of 260 to 310 μs or 270 to 300 μs.

[0106] T2L It can be controlled by the molecular mobility of the soft segment. The molecular mobility of the soft segment can also be controlled by the crosslinking density. The higher the crosslinking density, the smaller the molecular weight between crosslinking points and the smaller the space where the soft segment can move freely. Therefore, the molecular mobility becomes smaller.

[0107] In the pulsed NMR measurement at 50 °C, when divided into two components of the hard segment and the soft segment, the T2 relaxation time (T2 S ) of the hard segment is preferably 52 to 85 μs.

[0108] If T2 S is less than 52 μs, then E’(1) is likely to be large. In contrast, when T2 S exceeds 85 μs, E’(2) is likely to be small. T2 S being 52 to 85 μs helps E’(1) and E’(2) to satisfy the specific ranges mentioned above.

[0109] <Implementation method>

[0110] Describe the specific control methods for the molecular mobility of the soft segment and the hard segment to reduce E’(1) and increase E’(2).

[0111] <Molecular mobility of the hard segment>

[0112] The molecular mobility of the hard segment is affected by the rigid components in the molecule. The rigid components are cyanate ester and crystal, and by reducing these, the molecular mobility of the hard segment can be increased. Therefore, it is desirable to minimize the cyanate ester bond and enrich the urethane. Specifically, the details are as follows.

[0113] In the FT-IR measurement using diamond as the elastic member of the ATR crystal, the ratio of the peak intensity at 1415 cm -1 to the peak intensity at 1538 cm -1 , the value {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )} is preferably 0.50 to 0.65.

[0114] In the FT-IR analysis using diamond as the elastic member of the ATR crystal, the peak at 1415 cm -1 is the peak corresponding to the ring of isocyanurate. At the same time, the peak at 1538 cm -1 is the peak corresponding to the NH bending of the urethane bond. That is, the value of {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )} within the range of 0.50 to 0.65 indicates that there are few cyanate ester bonds in the elastic member.

[0115] {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )} value (peak intensity ratio) greater than 0.65 indicates the presence of many cyanate ester bonds in the elastic member. Therefore, the molecular mobility of the hard segment is likely to be small, and due to the rigidity of the cyanate ester, E’(1) is likely to be large. In contrast, if the value of {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )} is less than 0.50, E’(1) is instead likely to be too small. Therefore, the ratio is preferably in the range of 0.50 to 0.65. The value of {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )} is preferably 0.53 to 0.65.

[0116] In order to control the value of {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )} within the above specific range, methods such as reducing cyanate ester bonds and enriching urethane can be mentioned. Specifically, using a urethanation catalyst while avoiding a catalyst that promotes the formation of cyanate ester, the ratio of -NCO to -OH in the prepolymer being close to 1, and setting the reaction temperature during the reaction of the prepolymer material to 100 °C or below can be mentioned.

[0117] If within the range that satisfies E’(1) and E’(2), the polyurethane can have a rigid structure, such as polymeric MDI as a constituent component. Specifically, the details are as follows.

[0118] When defining the side of the cleaning blade that contacts the surface of the member to be cleaned as the front end side of the cleaning blade, the elastic member is in a plate shape, and this plate shape has at least a main surface (4) facing the member to be cleaned and a front surface (5) that forms the front end edge together with the main surface at the front end side. Then, assume a third line segment is drawn on the front surface parallel to the front end edge and at a distance of 0.5 mm from the front end edge. Then, represent the length of the third line segment as L’, and represent the points on the third line segment that are at distances of 1 / 8L’, 1 / 2L’, and 7 / 8L’ from one end side as P0’, P1’, and P2’ respectively.

[0119] Samples taken at P0', P1', and P2' respectively are heated and vaporized in an ionization chamber, and are heated to 1000 °C at a heating rate of 10 °C / s using a direct sample introduction type mass spectrometer that ionizes sample molecules. The detected amount of all ions thus obtained is denoted as M1, and the integrated intensity of the peak of the extracted ion thermogram corresponding to the m / z value in the range of 380.5 to 381.5 derived from polymeric MDI is denoted as M2. At this time, M2 / M1 is preferably less than 0.0010.

[0120] As the isocyanate, 4,4'-MDI which is highly reactive and has two equally reactive isocyanate groups is preferably used. At the same time, as described above, the use of polymeric MDI as the trifunctional MDI is preferably minimized, and in particular, not used at all. Specifically, M2 / M1 is preferably less than 0.0010. When M2 / M1 satisfies a specific range, E'(1) can satisfy a good range.

[0121] M2 / M1 is more preferably 0.0009 or less. The lower M2 / M1 is, the more preferred it is, and the lower limit of M2 / M1 is not particularly limited, but M2 / M1 is preferably 0.0000 or more.

[0122] If M2 / M1 is 0.0010 or more, due to the rigidity of polymeric MDI, E'(1) is likely to be larger.

[0123] Furthermore, in order to increase the molecular mobility of the hard segment, it is preferred to minimize the crystal structure as much as possible. Specifically, it is preferred to minimize materials that easily form crystal structures such as 1,4-butanediol, and to be rich in crosslinking agents such as trimethylolpropane. Crosslinking agents such as trimethylolpropane make it easier to create a distance between urethane bonds and make it difficult to form a crystal structure.

[0124] <Molecular mobility of the soft segment>

[0125] The molecular mobility of the soft segment is susceptible to the distance between crosslinking points and the structure between crosslinking points. Therefore, for example, by shortening the distance between crosslinking points and increasing the ester group concentration of the polyol, the molecular mobility of the soft segment can be reduced.

[0126] Examples of methods for shortening the distance between crosslinking points can include methods of increasing the concentration of crosslinking agents in the raw material composition of the elastic member. The distance between crosslinking points depends on the ester group concentration, but is preferably about 6000 to 9000 g / mol. The concentration of crosslinking agents in the raw material composition of the elastic member is also preferably 0.30 to 0.70 mmol / g, more preferably 0.40 to 0.61 mmol / g, and still more preferably 0.50 to 0.60 mmol / g from the perspective of the molecular mobility of the hard segment.

[0127] The method for calculating the concentration of the crosslinking agent is as described below. For example, the concentration can be quantified by pyrolysis GC / MS.

[0128] Polyols are detected by pyrolysis GC / MS. The measurement conditions are as shown below.

[0129] Equipment:

[0130] Pyrolysis equipment: “EGA / PY-3030D” (trade name, manufactured by Frontier Laboratories Ltd.)

[0131] Gas chromatography equipment: “TRACE 1310 Gas Chromatograph” (trade name, manufactured by Thermo Fisher Scientific K.K.)

[0132] Mass spectrometer: “ISQLT” (trade name, manufactured by Thermo Fisher Scientific K.K.)

[0133] Pyrolysis temperature: 500 °C

[0134] GC column: Inner diameter 0.25 mm × 30 m stainless steel capillary column

[0135] Stationary phase: 5% phenylpolydimethylsiloxane

[0136] Temperature rising condition: Maintain at a temperature of 50 °C for 3 minutes and rise to 300 °C at a rate of 8 °C / min.

[0137] MS condition mass number range: m / z 10 to 650

[0138] Scanning rate: 1 time / second

[0139] The type of polyol is qualitatively determined by GC / MS. A calibration curve is plotted in the GC analysis of qualitatively determined polyol species with known concentrations, and quantitative measurement is performed from the GC peak area ratio to calculate the concentration of the crosslinking agent in the raw material composition.

[0140] In addition, preferably, the distances between the crosslinking points of the soft segments are as uniform as possible. If the distances between the crosslinking points are non-uniform, the molecular mobility of the entire elastic member is likely to vary. For example, some components with higher molecular mobility may reduce E’(2), and some components with lower molecular mobility may increase E’(1). Therefore, in order for E’(1) and E’(2) to satisfy the above specific ranges, it is preferred to make the distances between the crosslinking points uniform while reducing the rigid components and increasing the crosslinking structure. The method for making the distances between the crosslinking points uniform is not limited, and examples thereof may include a method for producing polyurethane by a prepolymer method using a prepolymer having as uniform a molecular weight distribution as possible. It is also preferred to provide a simple material composition having a uniform molecular weight such that the molecular weight distribution is uniform. It is also preferred to reduce the use of chain extenders such as ethylene glycol that can make the molecular weight distribution non-uniform.

[0141] At this time, the number average molecular weight of the prepolymer is preferably from 8000 to 12000. The molecular weight can be analyzed by GPC in the above manner.

[0142] [Support member]

[0143] The cleaning blade of the present disclosure has a support member that supports the elastic member. The material constituting the support member is not particularly limited, and examples thereof may include the following materials. Metal materials such as steel plates, stainless steel plates, galvanized steel plates, and chromium-free steel plates; and resin materials such as 6-nylon and 6,6-nylon; etc.

[0144] In addition, the shape and structure of the support member are not particularly limited. For example, as Figure 2 shown, one end of the elastic member of the cleaning blade is supported by the support member.

[0145] [Elastic member]

[0146] The elastic member includes polyurethane. Specifically, the elastic member includes a polyurethane elastomer. The polyurethane elastomer constituting the elastic member can be mainly obtained from raw materials such as polyols, chain extenders, crosslinking agents, polyisocyanates, catalysts, and other additives. Hereinafter, these raw materials will be described in detail.

[0147] Examples of the polyol may include the following. Polyester polyols such as polyethylene adipate polyol, polybutylene adipate polyol, polyhexylene adipate polyol, (polyethylene / polypropylene)adipate polyol, (polyethylene / polybutylene)adipate polyol, and (polyethylene / polyneopentylene)adipate polyol; polycaprolactone-based polyols obtained by ring-opening polymerization of caprolactone; polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; and polycarbonate diol; etc. One of them may be used alone or two or more of them may be used in combination.

[0148] Among the above polyols, polyester polyols using adipic acid esters are preferred because polyurethane elastomers with excellent mechanical properties can be obtained. Polyester polyols using butylene adipate are more preferred.

[0149] As a chain extender, diols or polyols with three or more hydroxyl groups capable of extending the polyurethane elastomer chain can be used.

[0150] Examples of the diol may 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, xylene glycol (p-xylene glycol), and triethylene glycol.

[0151] Examples of the polyols with three or more hydroxyl groups may include trimethylolpropane, glycerin, pentaerythritol, and sorbitol. One of them may be used alone or two or more of them may be used in combination. These polyols with three or more hydroxyl groups are preferably used as crosslinking agents. Among the above polyols, trimethylolpropane is more preferred.

[0152] Examples of the above-mentioned polyisocyanates may include the following. 4,4'-diphenylmethane diisocyanate (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), and carbodiimide-modified MDI. Among the above-mentioned polyisocyanates, 4,4'-MDI, which has high reactivity and in which two isocyanate groups have the same reactivity, is preferred.

[0153] As the catalyst, a catalyst usually used for curing polyurethane elastomers can be used. For example, tertiary amine catalysts and the like can be mentioned, and specifically, the following can be exemplified. Amino alcohols such as dimethylethanolamine, N,N,N'-trimethylaminopropyl ethanolamine, N,N'-dimethylhexanolamine; trialkylamines such as triethylamine; tetraalkyl diamines such as N,N,N',N'-tetramethyl-1,3-butanediamine; triethylenediamine, piperazine-based compounds, and triazine-based compounds. Organic acid metal salts such as potassium acetate and potassium octoate can also be used. In addition, a metal catalyst usually used for urethanation, such as dibutyltin dilaurate, can be used. One of them can be used alone or two or more of them can be used in combination.

[0154] As the catalyst, N,N'-dimethylhexanolamine is preferred. Examples of commercially available catalysts of this type may include KAOLIZER No. 25 (trade name) manufactured by Kao Corporation. The catalyst is suitable for a catalyst in which urethanation is more dominant than cyanation. In addition, the above catalyst has a hydroxyl group at the end and reacts with itself while acting as a catalyst and inserts into the interior, so the possibility of chemical erosion due to leakage can be reduced. In addition, the catalyst is preferred because of its good reactivity. An ethylene glycol solution of potassium acetate is also preferred. Examples of commercially available catalysts of this type may include POLYCAT 46 (trade name, manufactured by Air Products and Chemicals Japan, Inc.)

[0155] For example, the polyurethane elastomer is preferably a cured product containing a mixture of at least one polyol selected from the group consisting of polyester polyols and polyether polyols, a polyol having three or more functional groups, and 4,4'-MDI.

[0156] For example, the polyurethane elastomer is preferably a cured product of a mixture containing at least one polyol selected from the group consisting of polyester polyols and polyether polyols, a polyisocyanate containing 4,4'-MDI, and a polyol having three or more hydroxyl groups.

[0157] Among the constituent components of the mixture as a raw material of the polyurethane elastomer, the content of the polyol is preferably 50 to 80% by mass and more preferably 55 to 70% by mass.

[0158] Among the constituent components of the mixture as a raw material of the polyurethane elastomer, the content of the polyisocyanate is preferably 15 to 50% by mass and more preferably 25 to 40% by mass.

[0159] Among the constituent components of the mixture as a raw material of the polyurethane elastomer, the content of the polyol having three or more hydroxyl groups is preferably 3 to 15% by mass and more preferably 5 to 10% by mass.

[0160] If necessary, additives such as pigments, plasticizers, waterproofing agents, antioxidants, UV absorbers, and light stabilizers can be formulated in the raw materials constituting the elastic member.

[0161] <Production method of cleaning blade>

[0162] The production method of the cleaning blade according to the present disclosure is not particularly limited, and any suitable method can be selected from known methods.

[0163] The production method of the elastic member containing the polyurethane elastomer is not particularly limited, but preferably includes the following steps. The polyurethane elastomer composition is preferably prepared by a prepolymer method using a prepolymer having as uniform a molecular weight distribution as possible. First, a step of reacting a polyol with a polyisocyanate to obtain a prepolymer is preferred. The NCO content in the prepolymer is not particularly limited, but is preferably 3.00 to 15.00% by mass and more preferably 6.00 to 10.00% by mass.

[0164] Subsequently, a mixture of a crosslinking agent and a catalyst (curing agent) is added to the obtained prepolymer and mixed to obtain a polyurethane elastomer composition. A polyol can be added to the curing agent. From the viewpoint of making the distance between crosslinking points uniform, it is preferable that the number average molecular weight of the polyol added to the curing agent matches the number average molecular weight of the polyol used in the prepolymer. For example, the difference in the number average molecular weight between the two is preferably 500 or less, 200 or less, or 100 or less.

[0165] After disposing the support member in a mold for forming the cleaning blade, the polyurethane elastomer composition is injected into the mold cavity and heated and cured to obtain a cleaning blade in which the plate-shaped blade member and the support member are integrated. A known mold release agent can be applied to the mold.

[0166] Optionally, the following method may be adopted: The polyurethane elastomer sheet and the above-mentioned polyurethane raw material composition are separately formed, cut into strips to prepare elastic members, and the bonding portions of the elastic members are overlapped on the support member coated or bonded with an adhesive, and then heated and pressed to bond with the support member.

[0167] <Processing Cartridge and Electrophotographic Image Forming Apparatus>

[0168] The cleaning blade can be used while being introduced into a processing cartridge configured to be detachably mounted to an electrophotographic image forming apparatus. Specifically, for example, in a processing cartridge provided with an image bearing member as a member to be cleaned and a cleaning blade configured to be able to clean the surface of the image bearing member, the cleaning blade according to this aspect can be used as the cleaning blade. The processing cartridge contributes to stably forming high-quality electrophotographs.

[0169] An electrophotographic image forming apparatus according to an aspect of the present disclosure includes, for example, an image bearing member such as a photoreceptor and a cleaning blade configured to be able to clean the surface of the image bearing member, wherein the cleaning blade is the cleaning blade according to this aspect. The above-mentioned electrophotographic image forming apparatus can stably form high-quality electrophotographic images.

[0170] [Examples]

[0171] The present invention will be described below with reference to production examples, examples, and comparative examples, but the present disclosure is not limited to these examples. As raw materials other than those shown in the examples and comparative examples, reagents or industrial chemicals are used.

[0172] In the following examples and comparative examples, the integrated formed cleaning blades shown are produced and evaluated. Figure 1 The formulations, characteristics of the obtained elastic members, and evaluation results of each example and comparative example are shown in Tables 1 and 2.

[0173] <Example 1>

[0174] [Support Member]

[0175] A galvanized steel sheet with a thickness of 1.6 mm is prepared and processed to obtain a support member having an L-shaped cross section, as shown by reference numeral 3 in Figure 2 the drawings.

[0176] A urethane-metal monolayer adhesive (trade name: Chemlok 219, manufactured by LORD Corporation) is coated on the portion of the support member that contacts the elastic member.

[0177] [Preparation of Raw Materials for Elastic Member]

[0178] (Prepolymer)

[0179] React the following isocyanate with a polyol at a temperature of 80 °C for 3 hours to obtain a prepolymer with an NCO content of 8.80% by mass.

[0180] · As the isocyanate, 327.0 g of 4,4'-diphenylmethane diisocyanate (trade name: Millionate MT, manufactured by Tosoh Corporation) (hereinafter referred to as 4,4'-MDI);

[0181] · As the polyol, 673.0 g of butanediol adipate-polyester polyol with a number-average molecular weight of 2500 (trade name: NIPPOLAN 3027, manufactured by Tosoh Corporation) (hereinafter referred to as PBA 2500).

[0182] (Curing agent)

[0183] Mix the following trimethylolpropane and N,N'-dimethylhexanolamine to prepare a curing agent.

[0184] · 84.3 g of trimethylolpropane (manufactured by Tokyo Chemical Industries Co., Ltd.) (hereinafter referred to as TMP);

[0185] · 0.25 g of N,N'-dimethylhexanolamine (trade name: KAOLIZER No.25, manufactured by Kao Corporation) (hereinafter referred to as No.25).

[0186] Mix the prepolymer and the curing agent to obtain a polyurethane elastomer composition.

[0187] The adhesive coating area of the support member is configured to protrude into the cavity of the forming die for the cleaning blade. Inject the above polyurethane elastomer composition into the forming die for the cleaning blade and cure it at a temperature of 130 °C for 5 minutes. Then, demold to obtain an integrally formed body of polyurethane and the support member.

[0188] Before injecting the above polyurethane elastomer composition, perform a demolding treatment on the inner surface of the die by coating a release agent A.

[0189] As the release agent A, use the following mixture

[0190] 5.06 g of "ELEMENT14 PDMS1000-JC" (trade name, manufactured by Momentive Performance Materials),

[0191] “ELEMENT14 PDMS10K-JC” 6.19 g (trade name, manufactured by Momentive Performance Materials),

[0192] “SR1000” 3.75 g (trade name, manufactured by Momentive Performance Materials) and

[0193] “EXXSOL DSP 145 / 160” 85 g.

[0194] The front end side of the polyurethane elastomer of the obtained integrally formed body was appropriately cut to obtain an elastic member in a plate shape having a main surface and a front end surface that together form the front end side edge. The angle of the front end side edge was set to 90°, and the distances in the short side direction, thickness direction, and long side direction of the elastic member were set to 7.5 mm, 1.8 mm, and 240 mm, respectively.

[0195] The obtained cleaning blade was evaluated by the following method.

[0196] [Calculation method of storage modulus]

[0197] The storage moduli E’(1) and E’(2) of the elastic member were measured by temperature-frequency dispersion using a dynamic viscoelasticity device, and the master curve with a reference temperature of 8 °C was plotted and calculated based on the time-temperature equivalence principle. Figure 5 Show the obtained master curve.

[0198] The measurement conditions of dynamic viscoelasticity are described below.

[0199] Device: Dynamic viscoelasticity measuring device (trade name: DMA EXPLEXOR 500N, manufactured by NETZSCH)

[0200] Measurement mode: Tensile

[0201] Static strain: 2%

[0202] Dynamic strain: 0.5%

[0203] Measurement temperature: -30 °C to 80 °C (step of 2 °C, 56 points)

[0204] Measurement frequency: 0.1 to 100 Hz (5 points)

[0205] From the obtained measurement results of dynamic viscoelasticity, the master curve with a reference temperature of 8 °C was plotted using the built-in software.

[0206] Based on the obtained master curve, mathematical approximation was performed based on the generalized Maxwell model.

[0207] The generalized Maxwell model is as follows.

[0208] [Mathematical formula 1]

[0209]

[0210] The above generalized Maxwell model is divided into a storage elastic modulus E′ and a loss elastic modulus E″ as follows.

[0211] [Mathematical formula 2]

[0212]

[0213] In the mathematical approximation, the number of terms in the generalized Maxwell model is set to the elastic term (E e )1 + the viscoelastic term (E i )20 (i = 1 to 20). τi is arbitrarily set at 20 points between 10 -8 and 10 5 .

[0214] Optimize E e and E i using the GRG nonlinear (Generalized Reduced Gradient method) to minimize the difference between E′ and E″ in the generalized Maxwell model and E′ and E″ in the total curve. Specifically, use the solver function in Excel.

[0215] From the obtained total curve approximation formula, obtain E’(1) (E’ at 1×10 -3 Hz) and E’(2) (E’ at 1×10 4 Hz).

[0216] Prepare the measurement sample as follows.

[0217] Prepare the sample to include the corner of the contact area of the elastic member with the member to be cleaned (e.g., the front edge). Cut the sample into strips with a length of 50 mm, a width of 2 mm, and a thickness of 1.8 mm.

[0218] [Measurement of T2 relaxation time]

[0219] Measure the spin-spin relaxation time (T2) by the solid echo method in pulsed NMR analysis.

[0220] Cut a sample from the elastic member of the cleaning blade at the following measurement position and cut it into a size of 1 mm×1 mm to prepare 1 g of the sample in a test tube.

[0221] The conditions for pulsed NMR measurement are as follows.

[0222] Equipment: “JNM-MU25” (trade name, manufactured by JEOL Ltd.)

[0223] Condition: Solid echo method

[0224] Measurement environment: 50 °C

[0225] Number of measurements: 128

[0226] The measurement results are divided into two components (soft segment and hard segment) by the least squares method in the built-in software to obtain their respective spin-spin relaxation times (T2 L and T2 S ).

[0227] In the present disclosure, according to the length of the relaxation time, the obtained T2 relaxation curve is divided into two components, namely, the hard segment and the soft segment. Specifically, by curve fitting of the following formula, the T2 relaxation curve is divided into two components, the hard segment and the soft segment, and the spin-spin relaxation time (T2 L ) of the soft segment and the spin-spin relaxation time (T2 S ) of the hard segment are calculated.

[0228] [Mathematical formula 3]

[0229]

[0230] M(t): Macroscopic magnetization

[0231] A L : Intensity of the long relaxation time component (soft segment) at t = 0

[0232] T2 L : T2 relaxation time of the long relaxation time component (soft segment)

[0233] A S : Intensity of the short relaxation time component (hard segment) at t = 0

[0234] T2 S : T2 relaxation time of the short relaxation time component (hard segment)

[0235] mi: Weibull coefficient

[0236] Measurement position: The length of the front-end side edge of the cleaning blade is set to L, and measurements are taken at positions 1 / 8L, 1 / 2L, and 7 / 8L away from one end side of the edge, and their average values are listed in Table 1.

[0237] [FT-IR Analysis of Elastic Members by ATR Method]

[0238] The peak intensity value of the elastic member at 1415 cm -1 and the peak intensity value of the elastic member at 1538 cm -1 are measured by the ATR method using FT-IR.

[0239] Samples are used by cutting out the elastic member of the cleaning blade from the measurement positions described below.

[0240] The conditions for FT-IR measurement are as follows:

[0241] Equipment: “FT / IR-4700” (trade name, manufactured by JASCO Corporation)

[0242] Measurement mode: ATR method (crystal: diamond)

[0243] Number of accumulations: 64

[0244] Measurement positions: Let the length of the front-end side edge of the cleaning blade be L, and measure at positions 1 / 8L, 1 / 2L, and 7 / 8L away from one end side of the edge.

[0245] From the obtained peak intensities, calculate the value of {(peak intensity at 1415 cm -1 ) / (peak intensity at 1538 cm -1 )}, and list its arithmetic mean in Table 1.

[0246] [Measurement methods for M1 and M2]

[0247] M1 and M2 are measured by the direct sample introduction method (DI method) in which the sample is directly introduced into the ion source without passing through gas chromatography (GC).

[0248] As the equipment, POLARIS Q manufactured by Thermo Fisher Scientific K.K. is used, and a direct exposure probe (DEP) is used.

[0249] When assuming that a line segment parallel to the front-end side edge and at a distance of 0.5 mm from the front-end side edge is drawn on the front end face of the elastic member, let the length of the line segment be L’, and let the points on the line segment at 1 / 8L’, 1 / 2L’, and 7 / 8L’ away from one end side be P0’, P1’, and P2’ respectively. Scrape off the polyurethane from P0’, P1’, and P2’ with a biological cutter.

[0250] Fix 0.1 μg of the sample taken at each of P0’, P1’, and P2’ to the filament located at the front end of the probe and directly insert it into the ionization chamber. Then, quickly heat the gas from room temperature to 1000 °C at a constant heating rate (10 °C / s), and detect the vaporized gas with a mass spectrometer.

[0251] Use the sum of the integrated intensities of all peaks in the obtained total ion current thermogram as the detected amount M1 of all ions.

[0252] The integrated intensity at the peak of the extracted ion thermogram corresponding to an m / z value in the range of 380.5 to 381.5 from the polymeric MDI is taken as M2, and M2 / M1 is calculated. Then, the arithmetic mean of the numerical values obtained at each of P0’, P1’ and P2’ is set as the value of M2 / M1 in the present disclosure.

[0253] [Roll Gap Width Evaluation]

[0254] As Figure 3 shown, the elastic member 2 of the cleaning blade 1 is brought into contact with the glass 8 having an antireflection film coated on its surface, and while moving the glass in the direction indicated by the arrow 10, the contact portion (roll gap) between the glass and the elastic member of the cleaning blade during the movement of the glass is observed using a laser microscope 9, and the obtained image is analyzed by image analysis software (Image-Pro Plus) to measure the roll gap width.

[0255] Observation: Using a laser microscope

[0256] Glass moving speed: 10 mm / s

[0257] Penetration level: 0.8 mm

[0258] Set angle: 25°

[0259] Measurement position: The length of the front end side edge of the cleaning blade is taken as L, and the roll gap widths at positions 1 / 8L, 1 / 2L, and 7 / 8L away from one end side of the edge are measured.

[0260] Since the light is blocked at the contact portion, it appears black when observed with a laser microscope. Therefore, the contact portion and the non-contact portion can be judged, and its width can be measured. The average value of the measurement results at the above measurement positions is used as the roll gap width for evaluation. Table 1 shows the results.

[0261] [Stick-Slip Evaluation]

[0262] As Figure 4 listed, while bringing the photoreceptor 6 as the member to be cleaned into contact with the elastic member 2 of the cleaning blade 1 and rotating it in the direction indicated by the arrow 7, the displacement of the contact portion is measured by a laser displacement meter 11. The displacement amount of the contact portion is evaluated as the stick-slip width.

[0263] The measurement conditions are as follows. As the photoreceptor, an electrophotographic photosensitive drum having a diameter of 24 mm and a surface layer containing a polyaryl compound resin is used.

[0264] · Penetration level of the cleaning blade: 0.8 mm

[0265] · Set angle: 25°

[0266] · Rotation speed of the electrophotographic photosensitive drum: 150 rpm

[0267] When stick-slip occurs, the distance from the laser displacement meter 11 to the contact portion of the elastic member 2 with the photosensitive member 6 of the cleaning blade 1 changes. Therefore, the stick-slip width can be evaluated by the laser displacement meter.

[0268] Equipment: Laser displacement meter (trade name: LJV-7000, manufactured by KEYENCE Corporation)

[0269] Sampling frequency: 64 kHz

[0270] Number of measurement points: 10000

[0271] Measurement position: Take the length of the front-end side edge of the cleaning blade as L, and measure the stick-slip widths at positions 1 / 8L, 1 / 2L, and 7 / 8L away from one end side of the edge.

[0272] Take the average value of the measurement results at the above measurement positions as the stick-slip width for evaluation. Table 1 shows the results.

[0273] <Evaluation of cleaning performance>

[0274] In the cyan cartridge of a color laser beam printer (trade name: HP LaserJet Enterprise Color M554dn, manufactured by HP Inc.), introduce the cleaning blade obtained by the above method as the cleaning blade for the photosensitive member to be cleaned. In addition, the toner in the developer of the cyan cartridge is completely replaced with toner 1, which will be described below.

[0275] Subsequently, place the toner in a low-temperature environment (temperature: 8 °C) for 24 hours, and perform 10k prints of images in the same environment. In the present disclosure, "k prints" means "×1000 prints". For example, 10k prints represent 10 × 1000 = 10,000 prints.

[0276] In addition, replace the used developer with a newly prepared cyan cartridge developer, and perform 10k prints of images again. Repeat this to perform a total of 150k prints of images. Output a halftone image as an evaluation image every 50k prints, and visually observe the occurrence of image defects (stripes on the image) caused by the cleaning blade to evaluate the image.

[0277] Grade the performance based on the following evaluation criteria to evaluate the cleaning performance. Table 1 shows the results.

[0278] Grade A: No image defects occur after 150k prints of images are completed.

[0279] Grade B: Image defects occur after 100k prints of the image.

[0280] Grade C: Image defects occur after 50k prints of the image.

[0281] Grade D: Image defects occur before 50k prints of the image are completed.

[0282] <Production Method of Toner 1>

[0283] Hereinafter, unless otherwise specified, "parts" are based on mass.

[0284] (Preparation Step of Aqueous Medium 1)

[0285] Into a reaction vessel equipped with a stirrer, a thermometer, and a reflux tube, 650.0 parts of ion-exchanged water were added, and 14.0 parts of sodium phosphate (dodecahydrate, manufactured by Rasa Industries, Ltd.) were introduced. While purging with nitrogen, the mixture was kept at 65 °C for 1.0 hour. While stirring at 15000 rpm using a T.K. HOMO MIXER (manufactured by Tokushu Kika Kogyo Co., Ltd.), an aqueous calcium chloride solution in which 9.2 parts of calcium chloride (dihydrate) were dissolved in 10.0 parts of ion-exchanged water was entirely added thereto to prepare an aqueous medium containing a dispersion stabilizer. Further, 10 mass% hydrochloric acid was introduced into the aqueous medium, and the pH was adjusted to 5.0 to obtain Aqueous Medium 1.

[0286] (Preparation Step of Polymerizable Monomer Composition)

[0287] · Styrene: 60.0 parts

[0288] · C.I. Pigment Blue 15:3 6.5 parts

[0289] The above materials were introduced into a grinder (manufactured by Mitsui Miike Kakoki Co., Ltd.), and further dispersed for 5.0 hours at 220 rpm using zirconia particles with a diameter of 1.7 mm to prepare a pigment dispersion. The following materials were added to the pigment dispersion.

[0290] · Styrene: 20.0 parts

[0291] · n-Butyl Acrylate: 20.0 parts

[0292] · Crosslinking Agent (Divinylbenzene): 0.3 parts

[0293] · Saturated Polyester Resin: 5.0 parts

[0294] (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 = 10000, molecular weight distribution Mw / Mn = 5.12)

[0295] · 7.0 parts of Fischer-Tropsch wax (melting point 78 °C)

[0296] It is kept at 65 °C and uniformly dissolved and dispersed at 500 rpm using a T.K.HOMO MIXER (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a polymerizable monomer composition.

[0297] (Granulation step)

[0298] While maintaining the temperature of the aqueous medium 1 at 70 °C and the rotation speed of the T.K.HOMO MIXER at 15000 rpm, the polymerizable monomer composition is introduced into the aqueous medium 1, and 10.0 parts of tert-butyl peroxyneodecanoate as a polymerization initiator is added. While maintaining 15000 rpm, granulation is carried out in a stirring device for 10 minutes.

[0299] (Polymerization and distillation step)

[0300] After the granulation step, the stirrer is replaced with a propeller stirring blade, and it is kept at 70 °C for 5.0 hours while stirring at 150 rpm to promote polymerization, and the polymerization reaction is carried out by raising the temperature to 85 °C and heating the reaction mixture for 2.0 hours.

[0301] After that, the reflux pipe of the reaction vessel is replaced with a cooling pipe, and the slurry is heated to 100 °C, thereby carrying out distillation for 6 hours to remove unreacted polymerizable monomers by distillation, thus obtaining a toner base particle dispersion.

[0302] (Polymerization of organosilicon compound)

[0303] In a reaction vessel equipped with a stirrer and a thermometer, 60.0 parts of ion-exchanged water is weighed, and the pH is adjusted to 4.0 using 10 mass% hydrochloric acid. It is heated to a temperature of 40 °C with stirring.

[0304] Then, 40.0 parts of the organosilicon compound methyltriethoxysilane is added, and the resulting mixture is stirred for more than 2 hours for hydrolysis. The end point of hydrolysis is confirmed by visually observing that the oil and water do not separate and form a single layer, and the reaction mixture is cooled to obtain a hydrolysis solution of the organosilicon compound.

[0305] After cooling the temperature of the obtained toner base particle dispersion liquid to 55°C, 25.0 parts of a hydrolyzed solution of a silicone compound was added to initiate the polymerization of the silicone compound. After maintaining the mixture as it was for 15 minutes, the pH was adjusted to 5.5 with a 3.0 mass% aqueous sodium bicarbonate solution. After maintaining it for 60 minutes while stirring at 55°C, the pH was adjusted to 9.5 with a 3.0 mass% aqueous sodium bicarbonate solution, and then maintained for 240 minutes to obtain a toner particle dispersion liquid.

[0306] (Washing and drying step)

[0307] After the polymerization step, the toner particle dispersion liquid was cooled, hydrochloric acid was added to the toner particle dispersion liquid to adjust the pH to less than 1.5, stirred for 1 hour, and then solid-liquid separation was performed using a pressure filter to obtain a toner filter cake. The toner filter cake was re-slurried with ion-exchanged water to obtain a dispersion liquid again, and then solid-liquid separation was performed using the above filter to obtain a toner filter cake.

[0308] The obtained toner filter cake was dried and classified in a constant temperature bath at 40°C for 72 hours to obtain Toner 1.

[0309] <Examples 2 to 10 and Comparative Examples 1 to 7>

[0310] As listed in Tables 1 and 2, except for changing the materials and / or compounding amounts, a prepolymer and a curing agent were prepared in the same manner as in Example 1 to obtain a polyurethane elastomer composition. A cleaning blade was produced using the obtained polyurethane elastomer, and the obtained cleaning blade was evaluated in the same manner as in Example 1. Tables 1 and 2 show the evaluation results. Figure 5 A master curve showing the relationship between the storage elastic modulus (E') and the measurement frequency, obtained in the same manner as in Example 1, of the elastic member according to Comparative Example 1 is shown.

[0311] Details of the materials used, other than those shown in Example 1, are as follows.

[0312] Polybutylene adipate-polyester polyol with a number average molecular weight of 1000 (trade name: NIPPOLAN 4009, manufactured by Tosoh Corporation) (hereinafter referred to as PBA1000).

[0313] Polybutylene adipate-polyester polyol with a number average molecular weight of 2000 (trade name: NIPPOLAN 4010, manufactured by Tosoh Corporation) (hereinafter referred to as PBA 2000).

[0314] Poly(hexamethylene adipate)-polyester polyol with a number-average molecular weight of 2,600 (trade name: NIPPOLAN 136, manufactured by Tosoh Corporation) (hereinafter referred to as PHA 2600)

[0315] Poly(hexamethylene adipate)-polyester polyol with a number-average molecular weight of 1,000 (trade name: NIPPOLAN 164, manufactured by Tosoh Corporation) (hereinafter referred to as PHA 1,000)

[0316] Poly(tetramethylene ether) glycol with a number-average molecular weight of 1,000 (trade name: PTG-1000SN, manufactured by Hodogaya Chemical Co., Ltd.) (hereinafter referred to as PTMG 1,000).

[0317] Polymeric MDI (product name: Millionate MR-400, manufactured by Tosoh Corporation) (hereinafter referred to as pMDI)

[0318] 1,4-Butanediol (manufactured by Tokyo Chemical Industries Co., Ltd.) (hereinafter referred to as 1,4-BD).

[0319] POLYCAT 46 (manufactured by Air Products Japan, Inc.) (hereinafter referred to as PC46).

[0320] TOYOCAT-RX5 (manufactured by Tosoh Corporation) (hereinafter referred to as RX5).

[0321] TEDA (triethylenediamine) (manufactured by Tosoh Corporation)

[0322] K-KAT XK-627 (manufactured by Kusumoto Chemicals, Ltd.) (hereinafter referred to as K-KAT)

[0323]

[0324]

[0325] Although the present disclosure has been described with reference to exemplary embodiments, it should be understood that the present disclosure is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation so as to cover all such modifications as well as equivalent structures and functions.

[0326] This application claims the benefit of Japanese Patent Application No. 2022-193730, filed on Dec. 2, 2022, which is incorporated herein by reference in its entirety.

[0327] Description of Reference Numerals

[0328] 1: Cleaning blade, 2: Elastic member, 3: Support member, 4: Main surface facing the member to be cleaned, 5: Front surface forming the front-side edge together with the main surface, 6: Member to be cleaned, 7: Rotation direction of the member to be cleaned, 8: Glass, 9: Laser microscope, 10: Glass movement direction, 11: Laser displacement meter.

Claims

1. An electrophotographic cleaning blade, comprising: An elastic member containing polyurethane; And a support member for supporting the elastic member, The electrophotographic cleaning blade cleans the surface of the member to be cleaned by bringing a part of the elastic member into contact with the surface of the moving member to be cleaned, wherein In an environment of 8°C, when the storage elastic modulus of the elastic member at a vibration frequency of 1×10 -3 Hz is denoted as E'(1) and the storage elastic modulus at a vibration frequency of 1×10 4 Hz is denoted as E'(2), E’(1) is from 12.0 to 18.0 MPa, and E’(2) is from 530.0 to 1500.0 MPa.

2. The electrophotographic cleaning blade according to claim 1, wherein The polyurethane is a polyurethane elastomer composed of hard segments and soft segments, and In the pulsed NMR measurement at an environment temperature of 50 °C, when divided into two components of the hard segment and the soft segment, the spin-spin relaxation time T2 of the soft segment L is 250 to 320 μs.

3. The electrophotographic cleaning blade according to claim 1 or 2, wherein In the FT-IR measurement using diamond as the elastic member of the ATR crystal, the ratio of the peak intensity at 1415 cm -1 to the peak intensity at 1538 cm -1 is 0.50 to 0.

65.

4. The electrophotographic cleaning blade according to any one of claims 1 to 3, wherein, When the side of the electrophotographic cleaning blade in contact with the surface of the member to be cleaned is defined as the front end side of the electrophotographic cleaning blade, The elastic member is in the shape of a plate, and the plate shape has a main surface facing the member to be cleaned and a front surface forming a front end side edge together with the main surface at least on the front end side, and Assuming that a third line segment parallel to the front end side edge and at a distance of 0.5 mm from the front end side edge is drawn on the front surface, The length of the third line segment is represented as L’, and The points on the third line segment at a distance of 1 / 8L’, 1 / 2L’ and 7 / 8L’ from one end side are represented as P0’, P1’ and P2’ respectively, When the samples taken at P0’, P1’ and P2’ respectively are heated and vaporized in an ionization chamber, and a direct sample introduction type mass spectrometer for ionizing sample molecules is used to heat them to 1000 °C at a heating rate of 10 °C / s, The detected amount of all ions thus obtained is represented as M1, and When the integrated intensity of the peak of the extracted ion thermogram corresponding to the m / z value in the range of 380.5 to 381.5 derived from polymeric MDI is represented as M2, M2 / M1 is less than 0.0010.

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

6. An electrophotographic image forming apparatus, comprising the electrophotographic cleaning blade according to any one of claims 1 to 5.

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