JP3776640B2 - Cleaning blade for electrophotographic image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning blade for an electrophotographic image forming apparatus , and in particular, on a toner image carrier that forms a toner image and thereafter transfers the toner image to a transfer material, such as a photoconductor and a transfer belt in electrophotography. It relates to a cleaning blade for removing toner.
[0002]
[Prior art]
In general, in an electrophotographic process, at least charging, exposure, development, transfer, and cleaning processes are performed on an electrophotographic photosensitive member. In such an electrophotographic process, the toner on the surface of the photoconductor cannot be entirely transferred to the transfer material due to reverse charging of the toner, unevenness and dirt on the surface of the photoconductor, insufficient energy of the transfer device, and the like. Remains. This residual toner blocks the photodischarge of the photoconductor in the exposure process of the photoconductor in the next cycle and inhibits the formation of a clear copy image, so the cleaning process after the transfer process is a very important process. is there.
[0003]
Currently, the mainstream cleaning method is a method using a cleaning blade. However, since such a cleaning blade is used by pressing it against a photoconductor with a predetermined force, a certain degree of high elasticity is required. The thing with the small characteristic change by a use environment is preferable.
[0004]
Therefore, conventionally, in order to reduce the environmental dependency, for example, a thermosetting polyurethane elastomer in which the peak temperature of tan δ is as low as possible has been prescribed. That is, such an elastomer is based on the recognition that the lower the peak top of tan δ is in the low temperature range, for example, the less the change in physical properties within the use environment of 0 ° C. to 40 ° C. It is.
[0005]
[Problems to be solved by the invention]
However, in reality, there is a problem that the cleaning characteristics are extremely deteriorated in a low temperature environment to be used.
[0006]
The present invention has been made in view of such circumstances, and an object thereof is to provide a sufficiently stable electrophotographic image forming apparatus for cleaning blade cleaning characteristics can be obtained even environment is changed.
[0007]
[Means for Solving the Problems]
The present invention for solving the above problems, t anδ (1Hz) lower than the peak temperature -10 ° C., the half width of the peak or less is 30 degrees, and the low temperature of the rubber region obtained from extrapolation of the complex modulus The cleaning blade for an electrophotographic image forming apparatus is composed of a thermosetting polyurethane rubber having a side end point lower than 0 ° C.
[0008]
Here, the tan δ (1 Hz) peak temperature of the thermosetting polyurethane rubber is preferably lower than −15 ° C.
[0012]
In the present invention, the peak temperature of tan δ is set to a low temperature range, the peak is as sharp as possible, and the rubber region of the complex elastic modulus is as low as possible, so that elasticity and hardness can be achieved even in the low temperature range of the usage region. much variation of the cleaning characteristics of which electrophotographic characteristics is based on the finding that stable.
[0013]
In the present invention, the peak temperature of tan δ is set lower than −10 ° C., preferably lower than −15 ° C., more preferably lower than −20 ° C., and the half width of the peak is 30 degrees or less, preferably 20 degrees. The end point on the low temperature side of the rubber region determined by extrapolation of the complex elastic modulus is set to be lower than 0 ° C. Thermosetting polyurethane rubber having satisfies this condition tanδ characteristics and the complex elastic modulus, for example, because having a stable cleaning characteristics at use temperature range of about 0 ° C. to 40 ° C..
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on examples.
[0015]
FIG. 1 is a graph showing the tan δ characteristics of the electrophotographic blade according to the example. FIG. 2 shows a graph of complex elastic modulus. The tan δ and complex elastic modulus were measured based on JIS K7198.
[0016]
As shown in FIG. 1, when an electrophotographic blade (Example 1) having a peak temperature of tan δ of −21 ° C. and a half width of 20 degrees was subjected to cleaning, charging and development tests with an actual machine, 0 ° C. And excellent cleaning characteristics, charging characteristics and development characteristics under both conditions of 40 ° C. and 40 ° C. The end point on the low temperature side of the rubber region determined by extrapolation of the complex elastic modulus in Example 1 was −9 ° C.
[0017]
On the other hand, for comparison, a tan δ peak temperature of about −4 ° C. and a half-value width of about 25 degrees (referred to as Comparative Example 1) and a tan δ peak temperature of about −8 ° C. A cleaning, charging and developing test was conducted on an electrophotographic blade having a width of about 30 degrees (referred to as Comparative Example 2) in the same manner, and the cleaning characteristics, charging characteristics and developing characteristics at 0 ° C. were not sufficient. Was recognized. The end points on the low temperature side of the rubber region obtained by extrapolating the complex elastic modulus of Comparative Examples 1 and 2 were 2 ° C. and 9 ° C., respectively.
[0018]
【The invention's effect】
As described above, the cleaning blade for an electrophotographic image forming apparatus of the present invention has a tan δ peak temperature lower than −10 ° C. and a peak half-value width of 30 ° C. or less. in temperature range of ℃ the effect of having a sufficiently stable cleaning characteristics.
[Brief description of the drawings]
FIG. 1 is a graph showing tan δ characteristics of an electrophotographic blade.
FIG. 2 is a graph showing a complex elastic modulus of an electrophotographic blade.

Claims (2)

t anδ (1Hz) lower than the peak temperature -10 ° C., the half width of the peak is less than 30 degrees, and the cold side of the end point of the rubber region obtained from extrapolation of the complex elastic modulus is lower than 0 ℃ A cleaning blade for an electrophotographic image forming apparatus comprising a thermosetting polyurethane rubber . 2. The cleaning blade for an electrophotographic image forming apparatus according to claim 1, wherein a peak temperature of tan δ (1 Hz) of the thermosetting polyurethane rubber is lower than −15 ° C. 3 .

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