JP2002214989A - Cleaning blade for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning blade for electrophotographic device which gives an excellent scraping ability even at a low temperature. SOLUTION: This cleaning blade for electrophotographic device comprises an elastic rubber member 3 and a supporting member 4 on which the elastic rubber member is adhered via an adhesive. Therein, the elastic rubber member has a two-layer structure consisting of an edge layer 1 which is in contact with an image carrier and a base layer 2 connected with the supporting member, the edge layer 1 consists of a material having JIS A hardness of 70-85 and impact resilience of 0-20% at 23 deg.C and the base layer 2 consists of a material having JIS A hardness of 65-70, impact resilience of 15-40% and permanent elongation of <=2%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning blade for an electrophotographic apparatus capable of exhibiting excellent scraping properties even at a low temperature.

[0002]

2. Description of the Related Art According to an electrostatic electrophotographic copying machine using plain paper as recording paper, an electrostatic charge is generally applied to the surface of an image carrier by discharging, and an image is exposed thereon to form an electrostatic latent image. Then, the charged toner is adhered to the electrostatic latent image and developed, the toner image is transferred to recording paper, and finally, the recording paper on which the toner image has been transferred is heated and pressed to remove the toner. Copying is performed by fixing on recording paper.

Accordingly, in order to sequentially perform copying on a plurality of recording papers, in the above-described process, after the toner image is transferred from the image carrier to the recording paper, the toner remaining on the surface of the image carrier is removed. It is necessary to remove such toner,
Usually, the cleaning is performed by a cleaning blade for an electrophotographic apparatus. The cleaning blade for an electrophotographic apparatus is generally formed of a support member made of a metal plate, an elastic rubber member, and an adhesive layer for joining the support member and the elastic rubber member.

A conventional elastic rubber member is, for example, a polyurethane elastic rubber member having a JIS A hardness of 65.
And a rebound resilience of 20 to 60% is used. In use, the edge of the elastic rubber member abutting on the surface of the image carrier is in contact with the rotating image carrier surface. When rubbing is performed, the surface of the image carrier is generally cleaned by vibrating with a minute amplitude and repelling toner particles remaining on the surface of the image carrier.

In recent years, in electrophotographic apparatuses, higher quality printed matter has been demanded, and accordingly, toner having a small particle size of toner particles (hereinafter referred to as small particle size toner) and toner particles having a spherical shape have been required. Toner (hereinafter, referred to as spherical toner) has been used. When such a toner is used, it is preferable that the force for pressing the cleaning blade for an electrophotographic apparatus be strong in order to scrape off the toner remaining on the surface of the image carrier. However, if the force for pressing the cleaning blade for the electrophotographic apparatus is too strong, there are problems that the rotational torque of the image carrier becomes too high and the surface of the image carrier is damaged.

In general, the physical properties of an elastic rubber member change depending on the temperature, and when the temperature is lowered, the elastic rubber member loses rubber elasticity and becomes hard. Therefore, the cleaning blade for an electrophotographic apparatus must be sufficiently pressed against an image carrier. Tended to be difficult. Therefore, in cold regions, even at low temperatures,
There is a need for a cleaning blade for an electrophotographic apparatus that can exhibit excellent scraping properties as at room temperature.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning blade for an electrophotographic apparatus capable of exhibiting excellent scraping properties even at a low temperature in view of the above situation.

[0008]

According to the present invention, there is provided a cleaning blade for an electrophotographic apparatus, comprising: an elastic rubber member; and a support member to which the elastic rubber member is adhered via an adhesive. Has a two-layer structure consisting of an edge layer in contact with the image carrier and a base layer in contact with the support member, and the edge layer is JIS A at 23 ° C.
Hardness is 70 to 85 and rebound resilience is 0 to 20%
The base layer has a JIS A hardness of 65 to 70 at 23 ° C. and a rebound resilience of 1 at 23 ° C.
A cleaning blade for an electrophotographic apparatus, which is made of a material having 5 to 40% and a permanent elongation of 2% or less. Hereinafter, the present invention will be described in detail.

A cleaning blade for an electrophotographic apparatus according to the present invention has a structure as schematically shown in FIG. 1, and its elastic rubber member is bonded to an edge layer and a support member which are in contact with an image carrier. It has a two-layer structure consisting of a base layer. In the elastic rubber member, the edge layer has a function of scraping off toner remaining on the image carrier, and the base layer has a function of adjusting a force of pressing the edge portion against the image carrier.

[0010] The edge layer is JIS
A hardness is 70 to 85 and rebound resilience is 0 to 2
It is made of 0% material. If the JIS A hardness is as low as less than 70, the peak value of the distribution of the pressing force applied to the edge layer when the toner remaining on the image carrier is scraped off may be too small to clean the small particle toner and the spherical toner. Is not sufficient, and if it exceeds 85, the surface of the image carrier may be damaged due to the hardness of the edge layer itself. The JIS A hardness is defined as JIS K73.
This is a value measured by a spring type A hardness tester according to No. 12.

If the rebound resilience exceeds 20%, stick-slip behavior of the edge portion occurs following the rotation of the surface of the image carrier, and the residual toner slips through when the edge portion is elastically deformed and gets caught. As a result, image defects such as streaks may occur. The rebound resilience is defined by JIS K
This is a value measured according to the rebound resilience test of No. 7312.

The above-mentioned base layer is JIS at 23 ° C.
A hardness is 65-70 and rebound resilience is 15-40%
And a material having a permanent elongation of 2% or less. When the JIS A hardness is less than 65, the physical properties of the edge layer become dominant.
The effect of the two-layer structure is diminished. Further, even if the hardness is lower than 65 or higher than 70, it is difficult to adjust the pressing force between the edge portion and the image carrier.

If the rebound resilience is less than 15%, the rubber elasticity (elastomeric property) becomes poor, the force of pressing the edge portion against the image carrier becomes too weak, and the residual toner may slip through, and exceeds 40%. Then, the edge of the cleaning blade for an electrophotographic apparatus vibrates due to the rubbing between the image carrier and the edge portion, and the ability to absorb the vibration transmitted from the edge layer is reduced.

If the permanent elongation exceeds 2%, when the blade is brought into contact with the image carrier for a long period of time, settling occurs, and the pressing force becomes weak, so that the residual toner may slip through. In addition, the said permanent elongation is a value measured according to the permanent elongation test of JISK7312. However, the elongation rate is fixed at 200%.

As described above, the elastic rubber member of the cleaning blade for an electrophotographic apparatus according to the present invention comprises two layers, the edge layer and the base layer. In the case of a cleaning blade for an electrophotographic apparatus in which the elastic rubber member is composed of only one layer of a material having high hardness and low rebound resilience, such as the above-mentioned edge layer, the edge is constantly pressed against the image carrier, so that the set is set. At low temperatures, the rubber elasticity disappears, the residual toner slips through, and image defects occur.

The edge layer and the base layer are preferably made of polyurethane. The polyurethane is manufactured using a polyol, an isocyanate, and a crosslinking agent as raw materials. The polyol is not particularly limited as long as it is generally used for forming a polyurethane, and examples thereof include polycaprolactam, polyethylene adipate, polybutylene adipate, and polyethylene butylene adipate. The above polyols may be used alone or in combination of two or more.

The isocyanate is not particularly limited as long as it is generally used for forming a polyurethane, and examples thereof include tolylene diisocyanate, 4,4-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate, isophorone diisocyanate, and the like.
Examples thereof include 1,4-cyclohexane diisocyanate and isomers thereof. Preferably, a polyurethane having excellent abrasion resistance is obtained.
-Diphenylmethane diisocyanate (MDI) and its isomers. The above isocyanates may be used alone or in combination of two or more.

As the crosslinking agent, a mixture of a low molecular weight diol and a low molecular weight triol is preferably used.
The low molecular weight diol is not particularly limited as long as it is generally used for forming a polyurethane, and examples thereof include 1,4-butanediol, ethylene glycol, diethylene glycol, 1,6-hexanediol, and neopentyl glycol. Can be mentioned. The low molecular weight triol is not particularly limited as long as it is generally used for forming a polyurethane, and examples thereof include trimethylolpropane and triisopropanolamine.

In producing the elastic rubber member made of the above polyurethane, a commonly used polyurethane molding method can be used, and examples thereof include the following methods. First, the dehydrated polyol and the isocyanate are mixed, and the mixture is heated to a temperature of 70 to 14;
The crosslinking agent and the like are added to the prepolymer obtained by reacting at 0 ° C. for 10 to 120 minutes, and the mixture is injected into a mold of a centrifugal molding machine preheated to 150 ° C. and cured for 5 to 10 minutes. After the curing reaction, the edge layer material similarly pretreated is poured onto the cured base layer and cured for 25 to 50 minutes. After the above-mentioned curing reaction, by taking out from the mold, a cylindrical two-layer structure sheet having a thickness of 2 to 3 mm is obtained. This is cut into a strip having a width of 8 to 20 mm and a length of 220 to 500 mm to obtain an elastic rubber member.

In the cleaning blade for an electrophotographic apparatus according to the present invention, the ratio of the thickness (a) of the edge layer to the sum (a + b) of the thickness (a) of the edge layer and the thickness (b) of the base layer ( a / (a + b)) is 0.05 to 0.3
It is preferred that If the above ratio (a / (a + b)) is less than 0.05, the thickness of the edge layer is insufficient to clean the small particle size toner and the spherical toner remaining on the surface of the image carrier, and 0 .3, the physical properties of the edge layer become dominant in the elastic rubber member,
The effect of having a two-layer structure is diminished.

The support member used in the present invention is not particularly limited. For example, a rigid metal, a metal having elasticity,
Those manufactured from plastics, ceramics and the like can be mentioned. Among these support members, a rigid metal is preferably used.

The method of bonding the elastic rubber member and the supporting member is not particularly limited, and examples thereof include a bonding method using an EVA-based, polyamide-based, or polyurethane-based hot-melt adhesive, or an epoxy-based or phenol-based adhesive. Among them, an adhesive method using a hot melt adhesive is preferred.

In the cleaning blade for an electrophotographic apparatus of the present invention, as described above, since the elastic rubber member is composed of the edge layer and the base layer having specific physical properties, the edge portion and the image carrier are pressed against each other. The power is well adjusted,
Further, even at a low temperature, the same cleaning performance as that of the small particle size toner and the spherical toner can be exhibited.

[0024]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1 to 3 and Comparative Examples 1 to 3 The edge layer and the base layer shown in Table 1 (each of 320 m
m × 15 mm), and adhered to a supporting member made of a plated steel plate to produce a cleaning blade for an electrophotographic apparatus.

The obtained cleaning blade for an electrophotographic apparatus is mounted on a commercially available plain paper copier (using an organic photoreceptor, at a speed of 10).
Sheets / min) at room temperature (23 ° C) and low temperature (10 ° C)
A print test was performed for each. The print test is 10
It was checked whether or not toner slippage occurred every 0 sheets, and the process was terminated when a streak caused by toner slippage was recognized in the printed matter, and the number of printed sheets was recorded.
If no streaks occurred even after printing 30,000 sheets, the test was terminated there. The results are shown in Table 1.

[0027]

[Table 1]

The polyurethanes in Table 1 each have the following composition. <Polyurethane A> 100 parts by weight of ethylene adipate prepolymer (NCO content: 16.5%) 47 parts by weight of polyethylene adipate Crosslinking agent (1,4-butanediol: trimethylolpropane = 80: 20) 2 parts by weight <polyurethane B> 100 parts by weight of ethylene adipate prepolymer (NCO content: 16.5%) 63 parts by weight of polyethylene adipate Crosslinking agent (1,4-butanediol: trimethylolpropane = 70: 30) 7 parts by weight

<Polyurethane C> 100 parts by weight of ethylene adipate prepolymer (NCO content: 8.0%) Crosslinking agent (1,4-butanediol: trimethylolpropane: ethylene glycol = 80: 10: 10) 7.6
Parts by weight <Polyurethane D> Caprolactam prepolymer (N
CO content 13.0%) 100 parts by weight Polycaprolactam 58 parts by weight 9.5 parts by weight of crosslinking agent (1,4-butanediol: trimethylolpropane = 65: 35)

<Polyurethane E> 100 parts by weight of caprolactam prepolymer (NCO content: 6.7%) 6.8 parts by weight of crosslinking agent (1,4-butanediol: trimethylolpropane = 75: 25)

[0031]

Since the present invention has the above-mentioned structure, it can clean both small-sized toner and spherical toner at a low temperature or at a normal temperature. A blade can be provided.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a cleaning blade for an electrophotographic apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Edge layer 2 Base layer 3 Elastic rubber member 4 Support member

Claims (3)

[Claims] 1. A cleaning blade for an electrophotographic apparatus, comprising: an elastic rubber member; and a support member to which the elastic rubber member is bonded via an adhesive, wherein the elastic rubber member is in contact with an image carrier. It has a two-layer structure consisting of an edge layer and a base layer bonded to the support member, wherein the edge layer
At 23 ° C., the JIS A hardness is 70 to 85,
The base layer is made of a material having a rebound resilience of 0 to 20%.
70. A cleaning blade for an electrophotographic apparatus, comprising a material having a rebound resilience of 15 to 40% and a permanent elongation of 2% or less. 2. The ratio (a / (a + b)) of the thickness (a) of the edge layer to the sum (a + b) of the thickness (a) of the edge layer and the thickness (b) of the base layer is 0.05. 2. The cleaning blade for an electrophotographic apparatus according to claim 1, wherein the number of the cleaning blade is from 0.3 to 0.3. 3. The cleaning blade for an electrophotographic apparatus according to claim 1, wherein the edge layer and the base layer are made of polyurethane.