Cleaning wiper blade

Abstract

The invention relates to a cleaning wiper blade comprising a tip adapted for contact with a photoconductive element. The tip is made of polyurethane with a talon greater than or equal to 0.35 at 23°C, a loss modulus greater than or equal to 5.59 MPa at 23°C, and a rebound of less than or equal to 21% at 23°C.

Description

Cleaning blade

[0001] The present invention relates to a cleaning blade used in an image forming apparatus.

[0002] In electrophotographic image forming devices (e.g., copiers and printers), a toner image formed on the surface of a photosensitive drum is transferred to a moving sheet, and any toner remaining on the surface of the photosensitive drum is removed by a cleaning blade.

[0003] It is desirable that the cleaning blade have appropriate elasticity to allow for appropriate deformation and appropriate abrasion resistance to ensure a long life. Generally, the cleaning blade is made of a thermosetting polyurethane resin or a thermosetting polyurethane elastomer.

[0004] International Publication No. 2017 / 111061

[0005] In image forming devices, the photosensitive drum and its surrounding components are often provided as a single unit. In this case, the lifespan of the unit is determined by the component with the shortest lifespan. The cleaning blade is a component with a short lifespan, and it is desirable to extend its lifespan even further.

[0006] The present invention provides a cleaning blade with a longer life.

[0007] One aspect of the present invention provides a cleaning blade, the cleaning blade having a tip portion that contacts a photoreceptor member, the tip portion being formed from polyurethane having a tan δ of 0.35 or more at 23°C, a loss modulus of elasticity of 5.59 MPa or more at 23°C, and a rebound resilience of 21% or less at 23°C.

[0008] In this embodiment, the wear resistance of the tip of the cleaning blade is improved, and the life of the cleaning blade can be extended.

[0009] The present invention relates to a cleaning blade for use in an embodiment of the present invention, a cleaning blade for use in an automobile, a cleaning method for cleaning a vehicle ...

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The drawings are not necessarily drawn to scale, and some features may be exaggerated or omitted.

[0011] 1, a cleaning blade 10 according to the embodiment is disposed near a photosensitive drum (photosensitive member) 1 of an electrophotographic image forming apparatus. As is well known, a transfer device 2 is disposed near the photosensitive drum 1. As a paper sheet S conveyed by a conveying device (not shown) passes through the nip between the photosensitive drum 1 and the transfer device 2, a toner image formed on the photosensitive drum 1 is transferred onto the sheet S.

[0012] Toner that has not been transferred to the sheet S and remains on the surface of the photosensitive drum 1 is removed by a cleaning blade 10. As is well known to those skilled in the art, the image forming apparatus has many other parts, but a description of these parts will be omitted.

[0013] The cleaning blade 10 has a bracket (support member) 11 made of hard plastic or metal and an elastic member 12 fixed to the bracket 11. Both the bracket 11 and the elastic member 12 extend parallel to the axial direction of the photosensitive drum 1. The bracket 11 is fixed in a fixed position in the image forming device and supports the elastic member 12. While the bracket 11 has high rigidity, the elastic member 12 has moderate elasticity. A tip 13 of the elastic member 12 is brought into contact with the outer circumferential surface of the photosensitive drum 1. The tip 13 in contact with the photosensitive drum 1 scrapes off residual toner on the photosensitive drum 1. The elastic member 12, particularly the tip 13, is elastically deformed by the reaction force from the photosensitive drum 1.

[0014] It is desirable to improve the wear resistance of the tip 13 of the cleaning blade 10 and extend the life of the cleaning blade 10. The applicant prepared numerous samples of the elastic member 12, measured the properties of these samples, and performed wear tests.

[0015] FIG. 2 shows the materials and properties of each sample.

[0016] Each sample of the elastic member 12 produced was polyurethane. The polyol used was an ester polyol (molecular weight 2000). The isocyanate used was 4,4'-diphenylmethane diisocyanate (MDI), "MILLIONATE MT" manufactured by Tosoh Corporation (Tokyo, Japan). The cross-linking agents, trimethylolethane (TME) and 1,1,1-trimethylolpropane (TMP), were both manufactured by Koei Chemical Industry Co., Ltd. (Tokyo, Japan). The chain extenders, 1,3-propanediol (1,3PD) and 1,4-butanediol (1,4BD), were both manufactured by Mitsubishi Chemical Corporation (Tokyo, Japan).

[0017] The rebound modulus, loss modulus, and storage modulus were measured at a temperature of 23°C and a humidity of 55% RH.

[0018] The rebound resilience was measured using a Lübke-type rebound resilience measuring device ("VR-6512" manufactured by Ueshima Seisakusho Co., Ltd., Tokyo, Japan) in accordance with JIS K6255 (2013).

[0019] The loss modulus and storage modulus were measured on test pieces for measuring the elastic modulus prepared for each sample. The test pieces had a thickness of 2 mm, a width of 3 mm, and a gauge length of 20 mm.

[0020] These test pieces were subjected to deformation at a frequency of 10 Hz with an amplitude of 2 μm, and the phase difference between dynamic stress and dynamic strain was measured. The measurement was performed using a Rheogel-E4000HP manufactured by UBM Co., Ltd. (Kyoto, Japan). The loss modulus and storage modulus were calculated by applying the strain to a known equation. The viscosity / elasticity ratio (tan δ) was obtained by dividing the loss modulus by the storage modulus.

[0021] The amount of wear was measured in the following experiment. The amount of wear was also measured at an air temperature of 23°C and a humidity of 55% RH. As shown in Figure 3, the length L of the sample elastic member 12 protruding from the end of the bracket 11 was 9 mm, and the thickness t was 2 mm. However, the length L was measured when the elastic member 12 was in a straight state.

[0022] As shown in FIG. 3 , a 0.3 μm-thick lapping film 20 was wrapped around the outer periphery of a rotatable cylinder 19. The cylinder 19 was a glass cylinder with a polycarbonate coating on its surface, simulating the photoreceptor drum 1. The lapping film 20 was "Lapping Film Abrasive #15000 A3-0.3SHT" available from 3M Japan Co., Ltd. (Tokyo, Japan). The reason for wrapping the lapping film 20 around the cylinder 19 was to accelerate the wear of the tip 13 of the elastic member 12 with the abrasive.

[0023] Next, the elastic member 12 of the cleaning blade 10 was brought into contact with the cylinder 19 wrapped with the wrapping film 20 at a contact angle θ and a contact load of 0.18 N / cm. The contact angle θ was 20 degrees. The photosensitive drum 1 was rotated at a peripheral speed of 460 mm / s, and the photosensitive drum 1 was slid against the elastic member 12 for a distance of 1,485 mm (the total length of five sheets of A4-sized paper).

[0024] The amount of wear on the tip 13 of the elastic member 12 was then measured. To measure the amount of wear, a laser microscope "VK-X250" manufactured by Keyence Corporation (Osaka, Japan) was used with a 150x magnification objective lens to photograph the edge of the tip 13, and the area of ​​the worn portion 22 was calculated from the photographed image. Although the photographing direction was tilted relative to the longitudinal direction of the elastic member 12 (the arrow in Figure 4 indicates the photographing direction), the area of ​​the worn portion 22 perpendicular to the longitudinal direction of the elastic member 12 could be calculated by mathematical correction. Photographs were taken at three locations along the longitudinal direction of the elastic member. The average area obtained for the three locations is shown in Figure 2.

[0025] The test results showed that the amount of wear was very small in samples 1 to 3, but large in samples 4 to 8.

[0026] Therefore, it is preferable that at least the tip portion 13 of the elastic member 12 be formed from polyurethane having a viscosity / elasticity ratio (tan δ) of 0.35 or more at 23°C, a loss modulus of elasticity of 5.59 MPa or more at 23°C, and a rebound resilience of 21% or less at 23°C. The tip portion 13 with these characteristics has a low rebound resilience and therefore high shock or vibration absorption. Furthermore, because the viscosity / elasticity ratio (tan δ) is high, it has a high ability to dissipate frictional energy generated by sliding with the photosensitive drum 1 as heat energy, resulting in high wear resistance. This can extend the life of the cleaning blade 10.

[0027] Although the present invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that changes may be made in form and detail without departing from the scope of the invention as set forth in the appended claims. Such changes, modifications and alterations are intended to be included within the scope of the invention.

[0028] For example, in the above embodiment, the cleaning blade comes into contact with the outer peripheral surface of the photosensitive drum 1 to clean the photosensitive drum 1. However, the cleaning blade according to the present invention may come into contact with a photosensitive belt wound around multiple rolls instead of the photosensitive drum 1 to clean the belt.

[0029] REFERENCE SIGNS LIST 1 Photosensitive drum (photosensitive member) 2 Transfer device 10 Cleaning blade 11 Bracket (support member) 12 Elastic member 13 Tip portion S Sheet

Claims

1. A cleaning blade having a tip that comes into contact with a photosensitive member, the tip being made of polyurethane having a tan δ of 0.35 or more in a 23°C environment, a loss modulus of elasticity of 5.59 MPa or more in a 23°C environment, and a rebound modulus of elasticity of 21% or less in a 23°C environment.

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