JP2018010092A - Sheet member and cleaning device including the sheet member, and image forming apparatus - Google Patents

Abstract

The present invention provides a sheet member that can alleviate a sticking error and suppress poor attachment irrespective of the accuracy (slight unevenness, deformation, distortion, etc.) of the surface to which the sheet member is a squeeze sheet.
A sheet member attached to a frame, which contacts a peripheral surface of a rotatable rotating body carrying a developer, and the developer leaks from a gap between the rotating body and the frame. In the sheet member to be prevented, the Young's modulus Y0 of the non-contact surface is 10 mgf / μm, where the surface that contacts the rotating body is the contact surface and the surface opposite to the contact surface is the non-contact surface. ² or more and 400 mgf / μm ² or less, and the Young's modulus decreases from the non-contact surface side to the contact surface side in the thickness direction of the sheet member, and is 50 μm from the non-contact surface. The ratio Y50 / Y0 between the Young's modulus Y50 at the internal position and the Young's modulus Y0 of the non-contact surface is 0.5 or less.
[Selection] Figure 4

Description

  The present invention relates to a blowout prevention sheet member used in a cleaning device or the like of an electrophotographic image forming apparatus, a cleaning apparatus including the same, and an image forming apparatus.

  The electrophotographic image forming apparatus forms a toner image on a photosensitive drum and transfers the toner image to a sheet to form an image. Such an image forming apparatus has a cleaning device that removes toner remaining on the photosensitive drum after the toner image is transferred to the sheet.

  As an example of the cleaning device, for example, toner adhering to the surface of the photosensitive drum is scraped off by a cleaning blade, and this is collected in a storage unit. At this time, a sheet member (squeeze sheet) is attached to the frame that forms the storage portion so that the toner does not leak from the gap between the storage portion that stores the collected toner and the photosensitive drum, and the tip of the sheet member extends in the longitudinal direction of the photosensitive drum. It is in contact.

  As the squeeze sheet, a photosensitive resin drum that is resistant to environmental changes is likely to damage the opposing photosensitive drum, and therefore, a squeeze sheet that is friendly to the photosensitive member and has shrinkability and flexibility is used. In addition, the squeeze sheet is generally attached to a predetermined attachment portion of a toner storage frame constituting a collected toner reservoir by bonding with a double-sided tape or the like.

  However, the frame is often formed of a resin material, and there is a difference in thermal expansion coefficient due to slight unevenness, small deformation, and environmental change. For this reason, if the squeeze sheet is simply pasted with a double-sided tape, undulation x may occur at the tip of the squeeze sheet 50, which is a contact portion with the photosensitive drum, due to thermal shrinkage due to environmental changes as shown in FIG. is there. When the squeeze sheet is swelled, the tip of the squeeze sheet does not completely adhere to the photosensitive drum, and the toner scraped off by the cleaning blade cannot be reliably removed.

  Thus, it has been proposed that when a squeeze sheet is attached, heat is applied while pulling to attach the squeeze sheet to prevent the squeeze sheet tip from wobbling (Patent Document 1).

  Further, a method for curving the shape of the squeeze sheet to prevent the squeeze sheet tip from wobbling has been proposed (Patent Document 2).

Japanese Patent Application No. 6-308802 Japanese Patent Application No. 10-336139

  However, as in Patent Document 1 described above, the method of sticking while pulling heat is likely to cause an error (difference in tension) depending on the person. In addition, there is a method of mechanically attaching in order to prevent errors, but with mechanization, the apparatus becomes very large and the cost increases.

  Further, as in Patent Document 2, the same method is applied to the curved and pasting method, and tension is generated. Therefore, a pasting error is likely to occur by a person, and undulation occurs depending on the use environment, and toner leakage cannot be completely prevented. Problems can occur.

  The present invention has been made in view of the above-described problems, and its purpose is to attach a sheet member, which is a squeeze sheet, regardless of the accuracy of the surface to which the material is applied (some irregularities, deformation, distortion, etc.). It is an object of the present invention to provide a sheet member that can alleviate errors and suppress poor attachment, and a cleaning device and an image forming apparatus using the sheet member.

A typical configuration according to the present invention for achieving the above object is a sheet member attached to a frame, which is in contact with an outer peripheral surface of a rotatable rotating body carrying a developer, and the developer is In the sheet member that prevents leakage from the gap between the rotating body and the frame body, when the surface that contacts the rotating body is a contact surface, and the surface opposite to the contact surface is a non-contact surface, The Young's modulus Y0 of the non-contact surface is 10 mgf / μm ² or more and 400 mgf / μm ² or less, and the Young's modulus is from the non-contact surface side to the contact surface side in the thickness direction of the sheet member. And the ratio Y50 / Y0 between the Young's modulus Y50 at a position 50 μm inside the non-contact surface and the Young's modulus Y0 of the non-contact surface is 0.5 or less. It is characterized by.

  According to the present invention, since the non-contact surface opposite to the contact surface where the sheet member contacts the rotating body has rigidity having a predetermined Young's modulus, when the sheet member is attached to the frame, the sheet No waviness at the tip. In addition, since the Young's modulus on the contact surface side where the sheet member contacts the rotating body is smaller than that on the non-contact surface side, the sheet member closely adheres along the peripheral surface of the rotating body, thereby suppressing the occurrence of developer leakage. it can.

1 is a configuration cross-sectional view illustrating a schematic configuration of an image forming apparatus. FIG. 2 is a structural cross-sectional view illustrating a schematic configuration of a cleaning device. It is a schematic sectional drawing for demonstrating the function of a squeeze sheet | seat. It is a schematic sectional drawing for demonstrating the structure of a squeeze sheet | seat. It is a schematic diagram which shows the place which measures the Young's modulus of a squeeze sheet. It is a graph which shows the relationship between the distance of the thickness direction of a squeeze sheet | seat, and Young's modulus. FIG. 4 is a schematic diagram showing the magnitude of the Young's modulus of the squeeze sheet in shades of color. It is a table | surface which shows an experimental result. It is a schematic sectional drawing for demonstrating the wave of a squeeze sheet.

  Next, the sheet member of the present invention will be described using an example in which the sheet member is used in a cleaning device of an image forming apparatus.

<Overall configuration of image forming apparatus>
FIG. 1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus. This image forming apparatus will be described together with an image forming operation. The image forming apparatus of the present embodiment is a contact charging type / transfer type electrophotographic image forming apparatus. Reference numeral 1 denotes a drum type electrophotographic photosensitive member (rotating image carrier for forming an electrostatic latent image). Hereinafter, it is a photosensitive drum). Around the photosensitive drum 1, a charging roller 2, an exposing unit 3, a developing unit 4, a transfer roller 5, and a cleaning device 6 are arranged.

  When forming an image, the circumferential surface of the rotating photosensitive drum 1 is uniformly charged by applying a bias to the charging roller 2, and light is emitted from the exposure means 3 in accordance with an image signal, whereby the electrostatic latent image is applied to the photosensitive drum 1. Form an image. The electrostatic latent image is visualized by developing the toner with the developer by the developing means 4.

  The recording sheet is conveyed by the conveying roller 7 so as to synchronize with the movement of the toner image formed on the photosensitive drum 1 as described above to the position of the transfer roller 5 as the photosensitive drum 1 rotates. When the sheet passes through the nip portion between the photosensitive drum 1 and the transfer roller 5, the toner image on the photosensitive drum 1 is transferred to the recording sheet P by applying a bias to the transfer roller 5.

  The recording sheet P to which the toner image has been transferred is conveyed to the fixing unit 8 where the toner image is fixed and then discharged to the discharge unit. On the other hand, the toner remaining on the photosensitive drum 1 after the toner image transfer is removed by the cleaning device 6.

<Cleaning device>
As shown in FIG. 2, the cleaning device 6 of this embodiment is provided with a cleaning blade 10 that is a cleaning member that cleans the toner Tk remaining on the photosensitive drum 1, and a squeeze sheet 50 upstream thereof.

  The cleaning blade 10 is made of a rubber member that contacts the longitudinal direction of the photosensitive drum 1, and is attached to the support sheet metal 11. The support metal plate 11 is rotatable about the swing shaft 12, and the cleaning blade 10 is pressed against the photosensitive drum 1 with a predetermined pressure by an urging spring 13. When the photosensitive drum 1 rotates in this state, the toner Tk remaining on the photosensitive drum 1 is scraped off by the cleaning blade 10, stored in the toner storage unit 15 configured by the cleaning frame body 14, and is transferred to the recovery unit by the transport screw 16. Collected.

  The squeeze sheet 50 is a long sheet member having a length substantially equal to the axial length of the photosensitive drum 1, and one end portion is attached to the cleaning frame 14 by a double-sided tape, and the other end portion is It is in contact with the photosensitive drum 1. Accordingly, the toner is prevented from leaking from the gap between the cleaning frame 14 and the photosensitive drum 1.

<Squeesheet>
Here, the configuration of the squeeze sheet 50 that is a sheet member that prevents the toner from being blown out from the gap between the cleaning frame 14 and the photosensitive drum 1 that is the rotating body will be specifically described.

  FIG. 3 is a view showing a state where the squeeze sheet 50 is in contact with the photosensitive drum 1. As shown in FIG. 3A, the squeeze sheet 50 is in contact with the photosensitive drum 1, as shown in FIG. 3A, the tip of the contact surface of the squeeze sheet 50 is in contact with the outer peripheral surface of the photosensitive drum 1. The collected toner Tk adhering to the toner pushes up the squeeze sheet 50 by the elasticity of the squeeze sheet 50 and proceeds to the cleaning blade 10 side. As shown in FIG. 3B, the collected toner is scraped off and the collected toner is repelled by the high pressure of the cleaning blade. Further, as shown in FIG. 3C, the collected toner Tk is dispersed in various directions such as an arrow, and the squeeze sheet 50 is in close contact with the photosensitive drum 1 without any gap, so that it does not leak out.

  As a necessary function of the squeeze sheet 50, the collected toner Tk scraped by the cleaning blade 10 is leaked from the gap between the cleaning frame 14 and the photosensitive drum 1 while the collected toner Tk is once passed along with the rotation of the photosensitive drum 1. Two functions are not required.

  Therefore, it is important that the squeeze sheet 50 is in contact with the photosensitive drum 1 so as not to leak the collected toner Tk scraped off from the cleaning blade 10 and does not damage the photosensitive drum 1. In addition, the squeeze sheet 50 is attached by being attached to the frame with a double-sided tape, but at this time, it is necessary to prevent the sheet tip contacting the photosensitive drum 1 from undulating.

  Therefore, the material of the squeeze sheet is important, and in this embodiment, as shown in FIG. When the surface on the side is the non-contact surface 50b, the hardness (waist strength) of the sheet is changed between the contact surface 50a and the non-contact surface 50b. Here, the hardness of the sheet is defined by Young's modulus.

  The squeeze sheet 50 according to the present embodiment is attached by sticking the non-contact surface side to the frame body 14, and the front end portion 50 c of the contact surface 50 a is in contact with the photosensitive drum 1. Here, the Young's modulus having a distance of N μm in the sheet thickness direction from the non-contact surface 50b of the squeeze sheet 50 is defined as YN. That is, the Young's modulus at the non-contact surface is Y0, the Young's modulus at a distance of 20 μm is Y20, and the Young's modulus at a distance of 50 μm is Y50.

At this time, the squeeze sheet 50 of the present embodiment is set so that the Young's modulus Y0 at the non-contact surface 50b is 10 mgf / μm ² or more and 400 mgf / μm ² or less. That is, the following relationship.

10 mgf / μm ² ≦ Y 0 ≦ 400 mgf / μm ² (Formula 1)
The Young's modulus decreases from the non-contact surface 50b toward the contact surface 50a, and the Young's modulus Y50 at a distance of 50 μm is less than half of the Young's modulus Y0 of the non-contact surface 50b. It is composed. That is, the following relationship.

Y50 / Y0 ≤ 0.5 (Formula 2)
Further, in the squeeze sheet 50 of the present embodiment, the average change rate of the Young's modulus from the non-contact surface 50b to the position at a distance of 20 μm has a Young's modulus from the position of 20 μm from the non-contact surface 50b to the position of 50 μm. It is configured to be greater than the average rate of change. That is, the following relationship.

[{(Y0−Y20) / Y0} / (20-0)] ≧ [{(Y20−Y50) / Y0} / (50−20)] (Formula 3)
From the relationship of the above formula 1, the squeeze sheet 50 of the present embodiment has a predetermined hardness on the non-contact surface 50b. As a result, the squeeze sheet 50 is less likely to swell at the tip when attached.

  And from the relationship of Formulas 2 and 3, the squeeze sheet 50 of this embodiment has a Young's modulus abruptly decreasing from the non-contact surface 50b toward the contact surface 50a. For this reason, the hard part with a high Young's modulus is extremely thin. If the hard part of the squeeze sheet is thick, the tip part contacting the photosensitive drum 1 may break, but the squeeze sheet of this embodiment is not configured as such. Also, the contact surface 50a with the photosensitive drum loses the hardness, and the collected toner Tk can be easily passed while being in contact with the photosensitive drum 1, and comes into close contact with the outer peripheral surface of the photosensitive drum 1.

  Hereinafter, the relationship of the Young's modulus in the squeeze sheet 50 of the present embodiment will be described in detail.

(Measurement method of Young's modulus)
In the present embodiment, the Young's modulus of the squeeze sheet 50 was measured using a micro-indentation hardness tester ENT-1100 (trade name) manufactured by Elionix Corporation. At appropriate points from the non-contact surface 50b of the squeeze sheet 50 toward the inside, a load-unloading test is performed under the following conditions, and a Young's modulus is obtained as a calculation result of the testing machine.

Test mode: Load-unloading test Load range: A
Test load: 100 [mgf]
Number of divisions: 1000 [times]
Step interval: 10 [msec]
Load holding time: 2 [seconds]
FIG. 5 is a schematic view showing a place where the Young's modulus of the squeeze sheet 50 is measured. In this embodiment, first, the squeeze sheet was divided into four equal parts in the longitudinal direction. And in the arbitrary part of the non-contact surface 50b (upper surface in FIG. 5) in the three cut surfaces 51 excluding both ends, the direction from the non-contact surface 50b to the inside (the direction of arrow A in FIG. 5). Then, the measurement and calculation described above were performed. Specifically, from the non-contact surface 50b toward the inside, the measurement and calculation described above were performed at positions of 2 μm from the surface to 30 μm, 10 μm from 30 μm to 60 μm, and 20 μm from 30 μm to 60 μm. And the value which averaged the measured value in the said three cross section in each measurement position was used as the value of the Young's modulus in the position. In principle, the Young's modulus is greater than zero.

(Measurement method of IR spectrum by μATR method)
In this embodiment, the IR spectrum was measured by the μATR method using a Fourier transform infrared spectrometer (trade name: Perkin Elmer Spectrum One / Spotlight300) manufactured by PerkinElmer (Diamond Crystal Universal ATR).

  As a general material of the squeeze sheet 50, for example, polyurethane, styrene-butadiene copolymer, chloroprene, butadiene rubber, ethylene-propylene-diene rubber, chlorosulfonated polyethylene rubber, fluoro rubber, silicone rubber, acrylic rubber, nitrile rubber, Any material having moderate elasticity and hardness such as an elastomer such as chloroprene rubber may be used. In particular, polyurethane that does not damage the photosensitive drum due to friction and has high wear resistance is preferable. Furthermore, considering that the permanent set is small, a two-component thermosetting polyurethane material may be used. As the curing agent, general urethane curing agents such as 1,4-butanediol, 1,6-hexanediol, hydroquinone diethylol ether, bisphenol A, trimethylolpropane, and trimethylolethane can be used.

  If these materials are simply used as the main component, because of the stretchable material, undulation will occur between the resin on the attachment surface and the stretchable material due to thermal expansion in the environment. Therefore, the point is to convert this stretchable material into a semi-resin, which is an important point in this embodiment. This makes it possible to suppress the waviness problem to an acceptable level.

  That is, the focus here is to make the Young's modulus of the non-contact surface of the squeeze sheet 50 strong enough to prevent undulations, and lower the Young's modulus from the non-contact surface 50b toward the contact surface. Is.

(Young's modulus at the non-contact surface of the squeeze sheet)
As a method for configuring the Young's modulus of the squeeze sheet 50 as described above, it is effective to control the molecular structure of the urethane rubber on the non-contact surface 50b.

  The urethane rubber can be synthesized using, for example, a polyisocyanate, a polyol, a chain extender (for example, a polyfunctional polyol), and a urethane rubber synthesis catalyst.

  When the urethane rubber is a polyester-based urethane rubber, a polyester-based polyol may be used as the polyol in order to synthesize the polyester-based urethane rubber. When the polyester urethane rubber is an aliphatic polyester urethane rubber, an aliphatic polyester polyol may be used as the polyol in order to synthesize the aliphatic polyester urethane rubber.

  Specific methods for increasing the Young's modulus of the non-contact surface of the urethane rubber squeeze sheet include a method of changing the degree of crosslinking of the urethane rubber or controlling the molecular weight of the raw material of the urethane rubber. Further, as a suitable method, there is a method of increasing the concentration of the isocyanurate group by adding an isocyanurate group to the urethane rubber. An isocyanurate group can be contained in urethane rubber as a group derived from polyisocyanate which is a raw material of urethane rubber.

  The squeeze sheet 50 of this embodiment is a squeeze sheet made of urethane rubber containing an isocyanurate group from the viewpoint of easy control of the Young's modulus of the non-contact surface 50b. In that case, in order to increase the Young's modulus of the non-contact surface 50b of the squeeze sheet 50, it is preferable to increase the content of isocyanurate groups on the surface (and the vicinity thereof) of the urethane rubber on the non-contact surface.

  Specifically, when the urethane rubber is a polyester urethane rubber, first, an IR spectrum is measured by the μATR method on the surface of the polyester urethane rubber on the non-contact surface. At that time, the ratio Isi / Ise between the intensity Isi of the C—N peak derived from the isocyanurate group in the polyester urethane rubber and the intensity Ise of the C═O peak derived from the ester group in the polyester urethane rubber is 0.50. The above is preferable.

The C—N peak is a peak at 1411 cm ^{−1 and} the C═O peak is a peak at 1726 cm ⁻¹ . This ratio Isi / Ise is based on the intensity of the C═O peak derived from an ester group that is not affected by the number of isocyanurate groups. Then, by comparing this standard with the intensity of the C—N peak derived from the isocyanurate group, it is a parameter that can qualitatively measure the number of isocyanurate groups.

  Here, as a standard of the contact pressure with which the squeeze sheet 50 contacts the photosensitive drum 1, it is necessary that the contact pressure does not cause mechanical damage to the photosensitive drum 1 and does not leak the collected toner Tk. In the present embodiment, the squeeze sheet 50 having the physical characteristics has a contact pressure of 0.0022 to 0.000022 mN / mm. If it is higher than 0.0022 m / N, the photosensitive drum is easily damaged, and the toner is difficult to pass through. Further, when the drum cartridge is reversed, the toner is likely to blow out if it is smaller than 0.000022 mN / mm.

If the Young's modulus of the squeeze sheet 50 itself is small, it is easy to follow the shape of the collected toner Tk. Conversely, if the Young's modulus is too large, it will be difficult to follow the shape of the collected toner Tk, and the squeeze sheet 50 will scrape off the toner. Therefore, the Young's modulus Y0 non abutment surface 50b in the squeegee sheet 50 of this embodiment, 400mgf / μm ² or less but more that is preferably 344mgf / μm ² or less, 250mgf / μm ² or less Preferred.

And the squeeze sheet 50 of this embodiment is a squeeze sheet made of urethane rubber containing an isocyanurate group as described above. In order to suppress the Young's modulus Y0 of the non-contact surface 50b of the squeeze sheet to a certain extent (400 mgf / μm ² or less), the content of isocyanurate groups on the surface (and the vicinity thereof) of the urethane rubber at the contact portion is limited to some extent. It is preferable to suppress to the amount of. Specifically, the ratio Isi / Ise is preferably 1.55 or less. In order to suppress the Young's modulus Y0 to 344 mgf / μm ² or less, the ratio Isi / Ise is preferably 1.35 or less. In order to suppress the Young's modulus Y0 to 250 mgf / μm ² or less, the ratio Isi / Ise is preferably 1.20 or less.

As described above, the Young's modulus Y0 non abutment surface 50b of the dip sheet in the present embodiment, 10 mgf / [mu] m ² or more 400mgf / μm ² is in the following range, 10 mgf / [mu] m ² or more 344mgf / μm ² or less in the range It is preferable that it exists in. More preferably, it is the range of 10 mgf / μm ² or more and 250 mgf / μm ² or less.

In order to make the Young's modulus Y0 of the non-contact surface of the squeeze sheet in the range of 10 mgf / μm ² or more and 400 mgf / μm ² or less, the ratio Isi / Ise is 0.50 or more and 1.55 or less. preferable. In order to make the Young's modulus Y0 to 10 mgf / [mu] m ² or more 344mgf / μm ² or less of the range, the ratio Isi / Ise is preferably 0.50 to 1.35. For further be in the range of Young's modulus Y0 of 10 mgf / [mu] m ² or more 250mgf / μm ² or less, the ratio Isi / Ise is preferably 0.50 to 1.20.

(Change in Young's modulus in the thickness direction of the squeeze sheet)
In addition, the squeeze sheet 50 of the present embodiment increases the Young's modulus of the non-contact surface 50b to some extent (10 mgf / μm ² or more and 400 mgf / μm ² or less), and has a Young's modulus from the non-contact surface toward the contact surface. It is comprised so that it may become small.

  Specifically, the ratio Y50 / Y0 between the Young's modulus Y50 and the Young's modulus Y0 at a position 50 μm inside the non-contact surface 50b of the squeeze sheet is 0.5 or less (preferably 0.2 or less). ing. As a result, even if the Young's modulus of the non-contact surface 50b is increased to some extent, it is possible to obtain good follow-up to unevenness and foreign matter at the contact portion with the photosensitive drum 1. Further, by setting the ratio Y50 / Y0 to 0.5 or less, it is possible to prevent scattering of the collected toner scraped off by improving the adhesion to the photosensitive drum 1.

Setting the ratio Y50 / Y0 to 0.5 or less while keeping the Young's modulus Y0 in the range of 10 mgf / μm ² or more and 400 mgf / μm ² or less means that the Young's modulus is rapidly increased from the non-contact surface to the inside of the squeeze sheet. It means to make it smaller.

  As described above, the squeeze sheet according to the present embodiment is configured such that the Young's modulus decreases rapidly from the non-contact surface toward the inside. The Young's modulus is configured to be small. Specifically, the average change rate of the Young's modulus from the non-contact surface 50b to the position inside 20 μm is equal to or greater than the average change rate of the Young's modulus from the position inside 20 μm to the position inside 50 μm. Yes.

  The average change rate of Young's modulus from the non-contact surface 50b to the position within 20 μm is represented by [{(Y0−Y20) / Y0} / (20−0)]. The average rate of change in Young's modulus from the position inside 20 μm to the position inside 50 μm is represented by [{(Y20−Y50) / Y0} / (50-20)]. Thereby, even if the Young's modulus decreases rapidly from the non-contact surface toward the inside (inside 50 μm from the surface), undulation due to environmental changes in the squeeze sheet is less likely to occur. Further, the followability to the irregularities on the surface of the photosensitive drum and foreign matters such as toner that may be present on the surface is improved.

  This is because the Young's modulus suddenly decreases from the vicinity of the non-contact surface, and on the inner side, the Young's modulus gradually decreases. This is thought to be because it became possible to disperse the difference in rate.

  Hereinafter, the average change rate [{(Y0−Y20) / Y0} / (20−0)] of Young's modulus from the non-contact surface 50b to the position within 20 μm is also expressed as “ΔY0-20”. In addition, the average change rate [{(Y20−Y50) / Y0} / (50−20)] of Young's modulus from the position inside 20 μm to the position inside 50 μm is also expressed as “ΔY20-50”. If expressed using these, the squeeze sheet 50 of the present embodiment is configured to satisfy ΔY0-20 ≧ ΔY20-50.

  Further, as shown in FIG. 6, the squeeze sheet in the present embodiment is a plane in which the horizontal axis is the distance from the non-contact surface (the non-contact surface is 0 μm), and the Young's modulus is the vertical axis. The Young's modulus YN (where 0 <N <50 [μm]) at an arbitrary position in the range from the non-contact surface to the position within 50 μm (the position where the distance from the surface of the contact portion is N [μm]) Is lower than the straight line (L0-50) connecting the Young's modulus Y0 and the Young's modulus Y50 (smaller than the straight line). This means that the profile of the change in Young's modulus when projecting from the non-contact surface 50b of the squeeze sheet 50 toward the inside is convex downward. Thereby, the followability to the unevenness | corrugation of the surface of the photosensitive drum 1 which is a contacted member, and the foreign material which may exist on the surface becomes more favorable.

  FIG. 7 is a schematic diagram showing the magnitude of the Young's modulus of the squeeze sheet according to the present embodiment in shades of color. FIG. 7 shows that the darker the color, the higher the Young's modulus. In FIG. 7, for convenience of explanation, the Young's modulus is shown to change stepwise, but the change of the Young's modulus of the squeeze sheet of this embodiment is made to change continuously.

  The change in the Young's modulus of the squeeze sheet is preferably continuous rather than stepwise. Being continuous means that there is no interface between portions having different Young's moduli that easily cause peeling or chipping.

<Rigidity of the entire squeeze sheet>
The rigidity of the entire squeeze sheet is a sheet that does not cause mechanical damage to the photosensitive drum. In this embodiment, the stiffness described in the stiffness test method (JIS-P8143) is defined as the Clark stiffness as a measure of the waist strength of the sheet. The standard size (width direction) of the test piece was 30 mm.

The Clark stiffness is reasonable 80 cm ³ or more 10000 cm ³ or less. If it is less than 80 cm ³ , the sheet is not waisted, and undulation is generated at high temperature and high humidity, resulting in a gap with the drum. Further, when the pressure is 10,000 cm ³ or more, the contact pressure of the toner scattering prevention member to the drum becomes high, and the toner scattering prevention member plays a role similar to that of the cleaning blade, leading to toner accumulation on the toner scattering prevention member.

The thickness of the squeeze sheet is preferably 25 μm or more and 350 μm or less. When the thickness is less than 25 μm, a wave is generated as in the case of Clark stiffness less than 80 cm ^{3. When the} thickness is greater than 350 μm, the toner scattering preventing member scrapes off the toner as in the case of Clark stiffness of 10,000 cm ³ or more.

And it is comprised as 1-50 N / mm < ² > (about 1-50 mgf / micrometer < ² >) as a Young's modulus in the contact surface 50a. If it is less than 1 N / mm ² , the contact pressure on the photosensitive drum is too weak and the toner is likely to scatter, and if it is greater than 50 N / mm 2, the contact pressure on the photosensitive drum is too strong to enter the toner. .

(Material and manufacturing method of squeeze sheet)
As described above, the squeeze sheet 50 of the present embodiment is a squeeze sheet made of urethane rubber. Among urethane rubbers, polyester urethane rubber is preferred from the viewpoint of mechanical strength such as wear resistance and difficulty of permanent deformation due to contact pressure (creep resistance), and among them, aliphatic polyester urethane rubber Is more preferable.

  As a method of controlling the Young's modulus of the non-contact surface of the squeeze sheet as described above, it is effective to control the molecular structure of the urethane rubber.

  The urethane rubber can be synthesized using, for example, a polyisocyanate, a high molecular weight polyol, a chain extender (for example, a polyfunctional low molecular weight polyol), and a urethane rubber synthesis catalyst. In order to synthesize the polyester-based urethane rubber, a polyester-based polyol may be used as the polyol. In order to synthesize the aliphatic polyester-based urethane rubber, an aliphatic polyester-based polyol may be used as the polyol.

  As a method for controlling the Young's modulus of the non-contact surface of the urethane rubber squeeze sheet as described above, specifically, the degree of crosslinking of the urethane rubber is changed, or the molecular weight of the raw material of the urethane rubber is controlled. The method of doing is mentioned. Among these methods, a method in which the concentration of isocyanurate groups derived from polyisocyanate, which is a raw material of urethane rubber, is increased toward the surface side of the urethane rubber is preferable from the viewpoint of accuracy in controlling Young's modulus.

  A urethane rubber containing an isocyanurate group (isocyanurate bond) has a larger cleaning angle β even when it has the same degree of hardness (for example, international rubber hardness) as compared with a urethane rubber having no isocyanurate group. Easy to maintain.

  Examples of the polyisocyanate include 4,4′-diphenylmethane diisocyanate (MDI, 4,4′-MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2, 6-TDI), xylene diisocyanate (XDI), 1,5-naphthylene diisocyanate (1,5-NDI), p-phenylene diisocyanate (PPDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4 Examples include '-dicyclohexylmethane diisocyanate (hydrogenated MDI), tetramethylxylene diisocyanate (TMXDI), carbodiimide-modified MDI, polymethylene polyphenyl isocyanate (PAPI), and the like. Among these, 4,4'-diphenylmethane diisocyanate is preferable.

  Examples of the high molecular weight polyol (aliphatic polyester-based polyol) include ethylene butylene adipate polyester polyol, butylene adipate polyester polyol, hexylene adipate polyester polyol, and lactone-based polyester polyol. Moreover, you may mix and use these. Of these aliphatic polyester-based polyols, butylene adipate polyester polyol and hexylene adipate polyester polyol are preferable in terms of high crystallinity. The higher the crystallinity of the aliphatic polyester polyol, the higher the hardness of the resulting polyester urethane rubber (polyester urethane rubber squeeze sheet), and the higher the durability of the squeeze sheet.

  The number average molecular weight of the high molecular weight polyol is preferably 1500 or more and 4000 or less, and more preferably 2000 or more and 3500 or less. The greater the number average molecular weight of the polyol, the higher the hardness, elastic modulus, and tensile strength of the resulting urethane rubber (urethane rubber squeeze sheet). Further, the smaller the number average molecular weight, the lower the viscosity and the easier the handling.

  Examples of the chain extender (polyfunctional low molecular weight polyol) include glycol. Examples of the glycol include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD), and 1,6-hexanediol. (1,6-HD), 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylylene glycol (terephthalyl alcohol), triethylene glycol and the like. Examples of chain extenders other than glycol include trihydric or higher polyhydric alcohols. Examples of the trihydric or higher polyhydric alcohol include trimethylolpropane, glycerin, pentaerythritol, sorbitol, and the like. Moreover, you may mix and use these.

  Urethane rubber synthesis catalysts are roughly classified into urethanization catalysts (reaction promotion catalysts) for promoting rubberization (resinization) and foaming, and isocyanurate formation catalysts (isocyanate trimerization catalysts). In the present invention, these may be mixed and used.

  Examples of urethanization catalysts include tin-based urethanization catalysts such as dibutyltin dilaurate and stannous octoate, triethylenediamine, tetramethylguanidine, pentamethyldiethylenetriamine, dimethylimidazole, tetramethylpropanediamine, N, N, and N. Examples include amine-based urethanization catalysts such as' -trimethylaminoethylethanolamine. In the present invention, these may be mixed and used. Among these urethanization catalysts, triethylenediamine is preferable in that the urethane reaction is particularly accelerated.

Examples of the isocyanuration catalyst include metal oxides such as Li ₂ O and (Bu ₃ Sn) ₂ O, hydride compounds such as NaBH ₄ , NaOCH ₃ , KO— (t-Bu), and borate. Alkoxide compounds such as, amine compounds such as N (C ₂ H ₅ ) ₃ , N (CH ₃ ) ₂ CH ₂ C ₂ H ₅ , N ₂ C ₆ H ₁₂ , HCO ₂ Na, CO ₃ (Na) ₂ , PhCO ₂ Na / DMF, CH ₃ CO ₂ K, (CH ₃ CO ₂ ) ₂ Ca, alkaline soap, naphthenate, and other alkaline carboxylate salt compounds, alkaline formate compounds, ((R ¹ ) ₃ − NR ² OH) -OOCR ³ quaternary ammonium salt compounds such as and the like. Examples of the combined catalyst (co-catalyst) used as the isocyanurate-forming catalyst include amine / epoxide, amine / carboxylic acid, and amine / alkylene imide. In the present invention, these may be mixed and used.

  Among the urethane rubber synthesis catalysts, N, N, N'-trimethylaminoethylethanolamine, which exhibits an action of an isocyanurate catalyst in addition to an action as a urethanization catalyst alone, is preferable.

  Moreover, additives, such as a pigment, a plasticizer, a waterproofing agent, antioxidant, a ultraviolet absorber, a light stabilizer, can also be used together as needed.

  The present inventors have found that the distribution of isocyanurate groups can be controlled as described above by synthesizing urethane rubber by the following method. That is, an aliphatic polyester-based polyol is used as a polyol, an isocyanurate-forming catalyst is applied to the inner surface of a mold, and a raw material in which the ratio of polyisocyanate and aliphatic polyester-based polyol is within a specific range is put in this mold, This is a method of synthesizing rubber.

  By applying the isocyanurate forming catalyst to the inner surface of the mold into which the raw material is put, the isocyanurate forming reaction is promoted particularly in the portion in contact with the inner surface of the mold. Therefore, it is preferable to use excess polyisocyanate with respect to the aliphatic polyester-based polyol. Furthermore, the isocyanurate-forming catalyst applied to the inner surface of the mold and the temperature of the mold act on the excess polyisocyanate to synthesize urethane rubber whose distribution of isocyanurate groups is controlled as described above. Is done.

The use amount (number of moles) of the aliphatic polyester-based polyol with respect to the polyisocyanate is preferably 30 mol% or more and 40 mol% or less with respect to the number of moles of the polyisocyanate. The smaller the aliphatic polyester polyol, the more easily the effect of excess polyisocyanate is obtained, and the Young's modulus Y0 of the non-contact surface of the squeeze sheet is easily controlled to 10 mgf / μm ² or more. On the other hand, by suppressing the excess degree of polyisocyanate to some extent, the Young's modulus Y0 of the non-contact surface of the squeeze sheet can be easily controlled to 400 mgf / μm ² or less.

  The mold temperature is preferably in the range of 80 ° C. or higher and 150 ° C. or lower, and more preferably in the range of 100 ° C. or higher and 130 ° C. or lower. In order to synthesize urethane rubber by reacting raw materials in the mold, it is preferable that the temperature of the mold is high to some extent from the viewpoint of reaction speed, but the higher the mold temperature, The difference in internal Young's modulus tends to be small.

  In addition to the method described above, the method for producing the squeeze sheet includes, for example, a method of producing a centrifugal force by introducing a liquid into a drum-shaped mold (centrifugal method), or a belt or groove-shaped mold. And a method of casting the solution into a mold (cast press method).

  In the above-described embodiment, the squeeze sheet provided in the cleaning device is exemplified as the sheet member that prevents the toner from blowing out. However, the squeeze sheet of the present invention can be applied not only to a cleaning device, but also to, for example, a squeeze sheet that abuts against a developing roller in a developing device and prevents toner from blowing out from a gap between the developing roller and the developing frame.

  Next, an Example is given and this invention is demonstrated. In the following examples and comparative examples, “part” means “part by mass”. The table of FIG. 8 shows the production conditions, analytical measurement, and physical property evaluation results of the squeeze sheet in each experiment.

<Example 1>
(Step of obtaining the first composition)
299 parts of 4,4′-diphenylmethane diisocyanate (hereinafter also referred to as “4,4′-MDI”) and 767.5 parts of butylene adipate polyester polyol (hereinafter also referred to as “BA2600”) having a number average molecular weight of 2600 are 80. The mixture was reacted at 0 ° C. for 3 hours to obtain a first composition (prepolymer) containing 7.2% by mass of NCO groups.

(Step of obtaining the second composition)
N, N, N′-trimethylaminoethylethanolamine (hereinafter also referred to as “ETA”) as a urethane rubber synthesis catalyst in 300 parts of hexylene adipate polyester polyol (hereinafter also referred to as “HA2000”) having a number average molecular weight of 2000 ) 0.25 part was added and stirred at 60 ° C. for 1 hour to obtain a second composition.

(Step of obtaining a mixture)
The first composition is heated to 80 ° C., the second composition heated to 60 ° C. is added thereto, and the mixture is stirred and mixed with the first composition and the second composition. Got. The number of moles of polyol in this mixture was 17 mol% based on the number of moles of polyisocyanate in the mixture. Hereinafter, this ratio is also expressed as “M (OH / NCO)”. In this example, M (OH / NCO) = 17 mol%.

(Process to obtain urethane rubber squeeze sheet)
A catalyst solution prepared by mixing 100 parts of ethanol with 100 parts of ethanol was spray-applied to one place on the inner surface of a mold for manufacturing a squeeze sheet. Thereafter, the catalyst solution was wiped onto a part of the inner surface of the mold (surface corresponding to the support contact portion of the squeeze sheet) with a urethane rubber blade.

  Then, after heating the mold to 110 ° C., a release agent is applied to the inner surface of the mold where the catalyst solution is not applied, and the mold is heated again to 110 ° C. And stabilized.

  Thereafter, the mixture was injected into the mold (inside the cavity). After the injection, it was heated at 110 ° C. (molding temperature) for 30 minutes to cause a curing reaction, and then demolded to obtain a urethane rubber plate. The obtained urethane rubber plate was cut with a cutting machine to form an edge portion, thereby obtaining a urethane rubber squeeze sheet. The obtained squeeze sheet had a thickness of 0.1 mm, a length of 20 mm, and a width of 345 mm.

(Evaluation method)
As an evaluation machine, a copy machine (trade name: iR-ADVC5255) manufactured by Canon Inc. was used. Then, the squeeze sheet obtained as described above is fixed to a part of the frame body in which the photosensitive drum and the toner storage portion are integrated, and the support portion contact surface (the catalyst liquid on the inner surface of the mold is removed). The surface was opposite to the coated surface).

  Using this cartridge, the endurance test of 10,000 sheets was conducted with a normal solid color image in a high temperature and high humidity environment of 30 ° C./80% RH and a low temperature and low humidity environment of 15 ° C./10% RH. The degree of toner scattering was confirmed. At that time, the squeeze sheet was not undulated, naturally, the toner was hardly scattered, and there was no problem that the collected toner did not enter (blank drop).

<Example 2>
In Example 1, 100 parts of ETA used for the preparation of the catalyst solution applied to the inner surface of the mold is represented by the following formula

  (Product name: DABCO-TMR, Sankyo Air Products) 100 parts. Further, the molding temperature was changed from 110 ° C. to 80 ° C. Except for these, squeeze sheets were produced in the same manner as in Example 1, and analytical measurements and physical property evaluations were performed.

  Using the cartridge, the same durability test as in Example 1 was performed. As a result, the squeeze sheet did not undulate, naturally, the toner hardly scatters, and there was a problem that the collected toner did not enter (blur-out). Did not occur.

<Example 3>
In Example 1, 100 parts of ETA used for the preparation of the catalyst solution applied to the inner surface of the mold was changed to 100 parts of a special amine (trade name: UCAT-18X, manufactured by San Apro Co., Ltd.). Also, the molding temperature was changed from 110 ° C to 150 ° C. Except for these, a squeeze sheet was produced in the same manner as in Example 1, and the same evaluation was performed. Using the cartridge, the endurance test of 10,000 sheets was performed with a normal single color solid image in a high temperature and high humidity environment of 30 ° C./80% RH and a low temperature and low humidity environment of 15 ° C./10% RH. The scattering condition was confirmed. At that time, the squeeze sheet was not undulated, naturally, the toner was hardly scattered, and there was no problem that the collected toner did not enter (blank drop).

<Example 4>
In Example 1, the amount of HA2000 in the step of obtaining the second composition was changed from 300 parts to 360 parts. In addition, 100 parts of ETA used for the preparation of the catalyst solution applied to the inner surface of the mold was changed to 100 parts of CH3COOK (trade name: POLYCAT46, manufactured by Air Products). Except for these, squeeze sheets were produced in the same manner as in Example 1, and analytical measurements and physical property evaluations were performed.

  Using the cartridge, the same durability test as in Example 1 was performed. As a result, the squeeze sheet did not undulate, naturally, the toner hardly scatters, and there was a problem that the collected toner did not enter (blur-out). Did not occur.

<Example 5>
In Example 1, the amount of 4,4′-MDI in the step of obtaining the first composition was changed from 299 parts to 350 parts. The amount of BA2600 was changed from 767.5 parts to 860 parts. In addition, the amount of HA2000 in the step of obtaining the second composition was changed from 300 parts to 170 parts. Also, 100 parts of ETA used for the preparation of the catalyst solution applied to the inner surface of the mold was changed to 90 parts of a 1: 1 (mass ratio) mixture of UCAT-18X (trade name) and DABCO-TMR (trade name). changed. Further, the molding temperature was changed from 110 ° C. to 90 ° C. Except for these, squeeze sheets were produced in the same manner as in Example 1, and analytical measurements and physical property evaluations were performed.

  Using the cartridge, the same durability test as in Example 1 was performed. As a result, the squeeze sheet did not undulate, naturally, the toner hardly scatters, and there was a problem that the collected toner did not enter (blur-out). Did not occur.

<Comparative Example 1>
In Example 1, the same evaluation as in Example 1 was performed except that a normal urethane sheet (squeeze sheet) was formed without applying the catalyst solution to the mold. As a result, the squeeze sheet wavy in a high temperature and high humidity environment. Then, the toner was scattered in the machine.

<Comparative example 2>
The same evaluation as in Example 1 was performed by changing the urethane sheet in Example 1 to a PET sheet of 25 μm. In this case, the Young's modulus Y0 of the non-contact surface was too high, and the collected toner was dammed up at the squeeze sheet, causing toner to fall off and causing in-machine contamination.

<Comparative Example 3>
The squeeze sheet prepared in Comparative Example 1 was attached by attaching it while being heated and evaluated. In a high temperature and high humidity environment, the squeeze sheet did not wave and did not fall off. However, when repeated, several of the 100 units were pulled too much, causing a gap between the squeeze sheet and the photosensitive drum, resulting in in-flight scattering. . Therefore, it is necessary to adjust the degree of pulling, and assembling is a problem.

<Comparative Example 4>
In Example 1, the amount of HA2000 in the step of obtaining the second composition was changed from 300 parts to 500 parts. The molding temperature was changed from 110 ° C to 140 ° C. Except for these, squeeze sheets were produced in the same manner as in Example 1, and analytical measurements and physical property evaluations were performed.

  Since this squeeze sheet has a small Young's modulus Y0 of the non-contact surface, the squeeze sheet wavy and the toner was scattered in the machine.

<Comparative Example 5>
In Example 1, the amount of 4,4′-MDI in the step of obtaining the first composition was changed from 299 parts to 350 parts. The amount of BA2600 was changed from 767.5 parts to 860 parts. Further, the amount of HA2000 in the step of obtaining the second composition was changed from 300 parts to 150 parts. Moreover, 100 parts of ETA used for the preparation of the catalyst solution applied to the inner surface of the mold was changed to 100 parts of UCAT-18X (trade name). Except for these, squeeze sheets were produced in the same manner as in Example 1, and analytical measurements and physical property evaluations were performed.

  In this squeeze sheet, since the Young's modulus Y0 of the non-contact surface is large, the toner falls off and the inside of the machine is stained.

P ... Recording sheet Tk ... Recovered toner 1 ... Photosensitive drum 2 ... Charging roller 3 ... Exposure means 4 ... Developing means 5 ... Transfer roller 6 ... Cleaning device 7 ... Conveying roller 8 ... Fixing section 10 ... Cleaning blade 11 ... Support metal plate 12 ... Oscillating shaft 13 ... biasing spring 14 ... cleaning frame 15 ... toner accommodating portion 16 ... conveying screw 50 ... squeeze sheet 50a ... abutting surface 50b ... non-contacting surface 50c ... tip portion 51 ... cutting surface

Claims (5)

A sheet member attached to the frame body, which contacts the outer peripheral surface of the rotatable rotating body carrying the developer and prevents the developer from leaking from a gap between the rotating body and the frame body In
When the surface that contacts the rotating body is a contact surface and the surface opposite to the contact surface is a non-contact surface, the Young's modulus Y0 of the non-contact surface is 10 mgf / μm ² or more and 400 mgf / μm ^2. And
The Young's modulus decreases in the thickness direction of the sheet member from the non-contact surface side toward the contact surface side, and the Young's modulus Y50 at a position within 50 μm from the non-contact surface; A sheet member characterized in that the ratio Y50 / Y0 of the non-contact surface to the Young's modulus Y0 is 0.5 or less.   2. The sheet member according to claim 1, wherein the Young's modulus is configured to continuously decrease from the non-contact surface side toward the contact surface side in the thickness direction of the sheet member. .   When the Young's modulus at a position inside 20 μm from the non-contact surface is Y 20, the average change rate of Young's modulus from the non-contact surface to the position inside 20 μm [{(Y 0 −Y 20) / Y 0} / ( 20-0)] is equal to or higher than the average rate of change of Young's modulus [{(Y20−Y50) / Y0} / (50-20)] from the position within the 20 μm to the position within the 50 μm. The sheet member according to claim 1. A cleaning member for cleaning the developer attached to the surface of the rotatable rotating body;
A frame housing the developer cleaned by the cleaning member;
The sheet member according to any one of claims 1 to 3, wherein the sheet member is attached to the frame body and abuts on an outer periphery of the rotating body.
A cleaning device comprising: A rotatable electrophotographic photoreceptor;
The cleaning apparatus according to claim 4, wherein the developer attached to the electrophotographic photosensitive member is cleaned.
An image forming apparatus comprising: