JP2003103686A - Elastic member and blade for electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic member realizing the low coefficient of friction without damaging the fundamental characteristics of an elastomer becoming a substrate and excellent in abrasion resistance, and the electrophotographic apparatus. SOLUTION: In the elastic member including the elastomer becoming the substrate used in the region brought into slide contact or rotary contact with a partner member, at least the contact part with the partner member has a layer comprising flexible diamond-like carbon and the Haydon type coefficient of static friction of a paired glass surface becomes large along with a friction speed, the coefficient of static friction at a friction speed of 6,000 m/min is not more than 2.5, and the fluctuation of the coefficient of static friction at the friction speed of 1,000-6,000 mm/min is not more than 1.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic member and a blade for an electrophotographic apparatus whose surface has a reduced friction coefficient without impairing the basic characteristics of an elastic body as a base material.

[0002]

2. Description of the Related Art An elastic member having an elastic body as a base material, which is used in a portion in sliding contact or rotational contact with a mating member, has a wide range of uses. Specifically, it is used in various blades for electrophotographic devices, rollers, belts, wipers for automobiles, wipers for machine tools, squeegees for printing electronic circuits, wipers for conveyor belts, skirts, and the like.

For example, in an electrostatic electrophotographic copying machine using plain paper as a recording paper, generally, an electrostatic charge is applied to the surface of a photoconductor by discharge, and an image is exposed on the electrostatic charge to form an electrostatic latent image. Then, the toner having the opposite polarity is attached to the electrostatic latent image to develop it, the toner image is transferred onto the recording paper, and finally the recording paper on which the toner image is transferred is heated and pressed to remove the toner. Copying is performed by fixing it on recording paper.

Therefore, in order to sequentially make a copy on a plurality of recording sheets, it is necessary to remove the toner remaining on the surface of the photosensitive member after transferring the toner image from the photosensitive member to the recording sheet in the above process. As one of the removing methods, there is known a blade cleaning method in which a blade is pressed against the surface of a photoconductor and the photoconductor is rubbed for cleaning. An elastic member is preferably used for a blade for an electrophotographic apparatus for this blade cleaning system.

However, when a conventional elastic member is used for a blade for an electrophotographic apparatus, a squeaking phenomenon due to sliding vibration at high temperature and high humidity; Inversion phenomenon in which the edge part is brought in the rotation direction of the photoconductor;
As a result of the advancement of spherical fine toner, removal of residual toner becomes difficult unless the contact pressure is increased, and driving torque rise and uneven rotation of the photoconductor tend to occur. There is a strong demand for a reduction in the friction coefficient.

As a method for improving the frictional characteristics of the elastic member, there has been proposed a method of applying or adding (blending) a plasticizer, a softening agent, oil or the like to an elastic body as a base material. However, this method has a problem that the plasticizer, the softening agent, the oil, or the like oozes out, and the powder or the like adheres to and deposits on it. Particularly, in the electrophotographic apparatus, there is a problem in that an image defect occurs due to toner sticking to the photoconductor and adversely affecting the electrical properties of the photoconductor.

As a method for improving the frictional characteristics of the elastic member, there has been proposed a method of curing the surface of the elastic body as a base material by ultraviolet irradiation or chemical crosslinking. However, this method has not been put to practical use because it is difficult to control the thickness of the hardened layer and side effects such as deterioration of wear resistance and chipping property.

As a method of improving the frictional characteristics of the elastic member, a method of mixing a solid lubricant into an elastic body as a base material has been proposed. Although this method does not have problems such as lubricant bleeding or thickness control, it causes uneven performance due to poor dispersion of the solid lubricant and hard solid lubricant scratches or scrapes the surface of the photoconductor. There was also a problem that the life of the photoconductor was shortened due to the excess.

Further, as a method of improving the frictional characteristics of the elastic member, a low friction substance containing an element such as fluorine is chemically bonded to the polymer chain constituting the elastic body as a base material,
Methods have been proposed for directing the fluorine-containing edge toward the surface.
Although this method is effective, it was necessary to pay attention to compatibility, abrasion, chipping, etc. between the fluorine-containing substance and the polymer.

[0010]

SUMMARY OF THE INVENTION In view of the above situation, the present invention has been made without deteriorating the basic characteristics of the elastic body as a base material.
An object of the present invention is to provide an elastic member and a blade for an electrophotographic apparatus, the friction coefficient of which is reduced only on the surface.

[0011]

SUMMARY OF THE INVENTION The present invention is an elastic member having an elastic body as a base material, which is used in a portion in sliding contact or rotational contact with a mating member, and at least a contact portion with the mating member is flexible. It has a layer made of diamond-like carbon, the coefficient of static friction of the Haydon type against the glass surface increases with the friction speed, the static friction coefficient at a friction speed of 6000 mm / min is 2.5 or less, and the friction speed is 1000 to 6000 mm / min. In the elastic member, the fluctuation of the static friction coefficient in is 1.0 or less. The present invention is described in detail below.

The elastic member of the present invention is used in a portion that makes sliding contact or rotational contact with a mating member. In the present specification, the elastic body includes rubber and resin having high deformability,
Even if the mold is not an elastic body such as a polyamide resin or a polyimide resin, it may be a film or sheet formed into a highly flexible shape. The elastic body is not particularly limited, and examples thereof include those made of polyurethane, polyester elastomer, natural rubber, synthetic rubber, polyamide resin, polyimide resin, fluorine resin and the like. Among them, polyurethane is preferably used because it has well-balanced mechanical properties.

In particular, when the elastic member of the present invention is used for a blade for an electrophotographic apparatus, the elastic body has a JI at 23 ° C.
It is preferably made of polyurethane having an SA hardness of 60 to 80. When the JIS A hardness at 23 ° C. is less than 60, the rigidity is insufficient for use in a blade and the pressure contact force cannot be secured, and when it exceeds 80, there is a problem that the blade is likely to damage the surface of the contacted surface. Among the elastic members of the present invention, the elastic body has a JIS A hardness of 6 at 23 ° C.
A blade for an electrophotographic apparatus, which is made of a polyurethane of 0 to 80, is also one aspect of the present invention.
The JIS A hardness is JIS K 7312.
The value is a value measured by a spring type A hardness tester in accordance with

At least the contact portion of the elastic member of the present invention with the mating member has a layer made of flexible diamond-like carbon (hereinafter also referred to as FDLC). Diamond-like carbon (hereinafter also referred to as DLC) is
A film made of carbon, which is made of DLC, has an intermediate property between diamond and graphite, achieves a low friction coefficient, and has excellent wear resistance. FDL
C is a material having this property of DLC and improved so that it can be formed into a film at low temperature and has stretchability. By having the layer made of FDLC, at least the contact portion of the elastic member of the present invention with the counterpart member realizes a low friction coefficient and is excellent in wear resistance.

The method for forming the FDLC layer on the elastic body as the base material is not particularly limited, but it is preferably formed by the plasma chemical vapor deposition method. FDL above
The thickness of the C layer is preferably 0.5 to 5 μm.
When it is less than 0.5 μm, it may be worn due to insufficient strength due to sliding and rotating contact, and when it exceeds 5 μm, the deformation followability is insufficient and the flexibility of the elastic body itself is impaired.
The film formation may take a long time and may not be economical.

At least in the contact portion of the elastic member of the present invention with the mating member, the coefficient of static friction of the Haydon type against the glass surface increases with the friction speed, and the coefficient of static friction at a friction speed of 6000 mm / min is 2.5 or less, and The fluctuation of the static friction coefficient at a friction speed of 1000 to 6000 mm / min is 1.0 or less. It is considered that the Haydon type coefficient of static friction with respect to the glass surface serves as an index of sliding characteristics at the time of starting, in particular, easiness of reversal phenomenon in which the edge portion is brought in the rotational direction of the sliding counterpart surface. Friction speed 1000
~ 6000 mm / min, in a normal electrophotographic device,
This corresponds to the low to medium speed range of the sliding speed of the electrophotographic apparatus blade and the contacted surface. From the problem of the moving speed of the Haydon type surface tester, the measurement at the friction speed is the limit, but from the measured value at the friction speed, the blade and the contacted surface for the electrophotographic device in the usual electrophotographic device It is considered that the friction coefficient can be sufficiently predicted in the high speed range of 8000 to 10000 mm / min, which is the sliding speed of. When the static coefficient of static friction between the Haydon type and the glass surface at a friction speed of 6000 mm / min exceeds 2.5, a reversal phenomenon tends to occur along the sliding mating surface at the time of startup, and damage due to abnormal deformation is likely to occur. Friction speed 1000-600
If the variation of the static friction coefficient at 0 mm / min exceeds 1.0, it is predicted that the static friction coefficient at 8000 to 10000 mm / min will increase, and in that case, a reversal phenomenon that is brought to the sliding mating surface at the time of startup occurs. It is easy to cause damage due to abnormal deformation.

At least the contact portion of the elastic member of the present invention with the counterpart member has a Haydon-type dynamic friction coefficient with respect to glass of 0.45 to 0.6 at a friction speed of 1000 to 6000 mm / min.
It is preferably 2. A lower Haydon type coefficient of dynamic friction with glass is preferable, but in the case of polyurethane, the practical lower limit is 0.45. If it exceeds 0.62, the sliding surface of the blade tends to be worn down, the driving torque of the photoconductor increases, and the rotation tends to become unstable.

As shown in FIG. 1, the coefficient of static friction of the Haydon type against glass at a friction rate of 6000 mm / min was measured by using a Haydon type surface tester under an environment of 20 to 25 ° C. and a relative humidity of 40 to 55%. An initial peak resistance when a sample with an edge length of 20 mm was pressed against a glass mirror surface at an angle of 26 ° with a load of 0.98 N at a position 5 mm inward from the blade tip edge, and the glass surface was moved at 6000 mm / min ( N) is detected by a load cell and the recording chart is calculated and averaged by an analyzer. In addition, the Haydon-type dynamic friction coefficient against glass at the friction speed of 1000 to 6000 mm / min is stable sliding except the initial peak resistance when the glass surface is moved at 1000 to 6000 mm / min under the same apparatus and conditions. The sliding resistance (N) was detected by a load cell, and the recording chart was calculated and averaged by an analyzer.

The elastic member of the present invention can be molded and processed to be used for various industrial rollers, flooring materials, conveyance and transmission belts, electrophotographic members, etc., among which blades for electrophotographic apparatus are suitable. Used for. The above-mentioned blade for electrophotographic apparatus can be used for static elimination, charging, development, transfer or cleaning in an electrophotographic apparatus. Particularly, in an electrophotographic apparatus, it is suitable for a cleaning blade for removing toner remaining on the surface of the photoconductor by rubbing the photoconductor after transfer, or a cleaning blade for a transfer belt adopting a transfer belt system having a high friction coefficient. Used for.

[0020]

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

(Example 1) <Formation of substrate> 117.6 parts by weight of 4,4'-diphenylmethane diisocyanate was added to 100 parts by weight of polybutylene adipate diol having a molecular weight of 2000, and the mixture was added at 70 ° C. under a nitrogen gas atmosphere. The mixture was stirred for 1 to 4 hours to prepare a prepolymer having an isocyanate group content of 16.3% by weight. Separately, 77.5 parts by weight of a polybutylene adipate diol having a molecular weight of 2000, 11.9 parts by weight of a curing agent obtained by mixing 1,4-butanediol and trimethylolpropane in a weight ratio of 60:40, and a temperature-sensitive catalyst ( A curing agent composition was prepared by mixing 0.19 parts by weight of SA1102 manufactured by San-Apro Co., Ltd. 89.6 parts by weight of the curing agent composition was added to 100 parts by weight of the prepolymer so that the OH group / NCO group = 0.88 molar ratio, and the mixture was stirred and mixed at 70 ° C. Then, this mixture was poured into a mold for a cleaning blade of an integrally molded type, which was held at a temperature of 145 ° C. while holding a support having an adhesive treatment, and was cured by reaction in the mold for 10 minutes at 145 ° C., and the tip was 1.6 mm. A molded body for a cleaning blade comprising a thick polyurethane and a support is prepared,
After further aging at room temperature for 7 days, the edge portion of polyurethane was cut and finished to obtain a cleaning blade composed of a blade member and a support as shown in FIG. A sample for hardness measurement was prepared from this base material elastic body part, and JIS K
Hardness was measured according to 7312. On the other hand, the mixture of the prepolymer and the curing agent composition was poured into a 2 mm-thickness plate molding die for measuring physical properties, and cured and aged under the same conditions as the cleaning blade to obtain a physical property measuring plate.

<Formation of FDLC layer> Plasma chemical gas was formed on the long side surface (11 surface in FIG. 1) and the tip surface (12 surface in FIG. 1) forming the edge portion of the elastic base material of the obtained cleaning blade. A 2 μm thick FDLC vapor deposition film was formed by a phase vapor deposition method to obtain a cleaning blade in which an FDLC layer was formed at a contact portion with a mating member.

<Evaluation> F is applied to the contact portion with the obtained mating member.
A cleaning blade piece having an edge length of 20 mm was cut out from the cleaning blade on which the DLC layer was formed, and the edge was measured with a Haydon-14 type surface property tester shown in FIG. The moving table on which mirror glass is attached is applied at a speed of 1000 to 6 by applying a load of 0.98 N / 20 mm in the reading direction at an angle of 26 °.
The static friction coefficient against glass and the dynamic friction coefficient were measured from the sliding resistance applied to the cleaning blade piece when moved in the reading direction at 000 mm / min. The measurement of the coefficient of friction with the Haydon method against glass was performed 5 times, and the average value of 3 times excluding the maximum value and the minimum value was taken as the measured value. In addition, as shown in FIG. 2, when a test piece having an edge length of 10 mm was cut out from the obtained cleaning blade, brought into contact with the mating surface at an angle of 26 °, and bitten 1.0 mm in the mating surface in the direction perpendicular to the mating surface. Was measured using a load cell connected to the mating surface. Further, the permanent deformation rate was determined after leaving the mating surface at a depth of 1.5 mm in the direction perpendicular to the mating surface for 5 days at 15 ° C. and 5 days at 45 ° C.

Next, a cleaning blade having an FDLC layer formed on the contacting portion with a mating member was mounted on a printer LJ-4000 manufactured by Hewlett-Packard Co., at 33 ° C.
Under a high temperature and high humidity condition of 85% RH, a 10 mm square fine line grid image was printed 16 times per minute on A4 paper by a sound test for the presence of abnormal sliding noise, and the presence or absence of toner fusion was visually checked. Investigated by. The temperature around the cleaning blade at this time was 50 to 55 ° C. After printing 10,000 more images, set the edge of the cleaning blade to 200
It was observed with a double microscope and evaluated according to the following criteria. ◯: No edge chipping was observed. Δ: Although a slight edge chipping was recognized, it was within a range where there was no practical problem. X: Remarkable edge chipping was recognized. The results are shown in Table 1.

(Comparative Example 1) A cleaning blade was obtained in the same manner as in Example 1 except that no surface treatment was performed on either the long side surface or the tip surface forming the edge portion of the elastic base material of the cleaning blade. , Evaluated. The results are shown in Table 1.
It was shown to.

[0026]

[Table 1]

[0027]

According to the present invention, it is possible to provide an elastic member and a blade for an electrophotographic apparatus in which the friction coefficient is reduced only on the surface without impairing the basic characteristics of the elastic body as a base material.

[Brief description of drawings]

FIG. 1 is a schematic view showing a method for measuring a friction coefficient with respect to glass using a Haydon type surface property tester.

FIG. 2 is a schematic view showing an apparatus for measuring a contact force.

[Explanation of symbols]

1 blade member 11 Long sides that form the edge 12 Tip surface forming the edge 13 Flexible diamond like carbon layer 2 support 3 glass mirror surface 4 blade members 5 support 6 load cell 7 slide table 8 micrometer

Continued front page    (72) Inventor Toshio Yamamoto             Bando 3-2-15, Meiwadori, Hyogo-ku, Kobe             Inside Chemical Co., Ltd. F-term (reference) 2H134 GA01 HD01 HD02 HD04 HD19                       KD03 KD08 KE01                 3J103 AA85 BA41 FA30 GA02 HA12                       HA52                 4F071 AA11 AA26 AA43 AA53 AA54                       AA60 AB03 AG16 AH16                 4F100 AA37B AK51 AR00A BA02                       EJ61B GB41 JK07A JK12B                       JK16B YY00B

Claims (4)

[Claims] 1. An elastic member having an elastic body as a base material, which is used in a portion in sliding contact or rotational contact with a mating member,
At least the contact portion with the mating member has a layer made of flexible diamond-like carbon, and the coefficient of static friction of the Haydon type against the glass surface increases with the friction speed, and the coefficient of static friction at a friction speed of 6000 mm / min is 2.
5 or less and a friction speed of 1000 to 6000 mm
The elastic member is characterized in that the variation of the static friction coefficient per minute is 1.0 or less. 2. The elastic member according to claim 1, wherein the layer made of flexible diamond-like carbon is formed by plasma enhanced chemical vapor deposition and has a thickness of 0.5 to 5 μm. . 3. The Haydon equation-to-glass dynamic friction coefficient at a friction velocity of 1000 to 6000 mm / min is 0.45 to 0.62 at least in the contact portion with the mating member. Elastic member. 4. The elastic body is made of polyurethane having a JIS A hardness of 60 to 80 at 23 ° C.,
A blade for an electrophotographic apparatus, comprising the elastic member described in 2 or 3.