JP2001125298A - Electrophotographic image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic image forming device and a process cartridge each using an electrophotographic photoreceptor which is used in an injection electrifying process using a magnetic brush as an electrifier, has a surface layer comprising a resin formed in a film by three-dimensional crosslinking, suppresses scuffing due to the pressing of charged carriers leaked from the magnetic brush on the photoreceptor in transfer and suppresses the occurrence of image defects due to scuffing. SOLUTION: The surface layer of the electrophotographic photoreceptor is based on a resin formed in a film by three-dimensional crosslinking. A curve showing the relation between the hardness (H) of the surface layer and the indenting depth (h) of a depressor in a physical property test of a surface coating in a certain environment (22.5 deg.C/50% RH) has no inflection point and the Universal hardness HU of the surface layer is >=200 [N/m2].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrophotographic image forming apparatus and a process cartridge for an injection charging process using a magnetic brush for a charger.

[0002]

2. Description of the Related Art Conventionally, as a charging device, a corona charger which generates a corona discharge by applying a high voltage to a wire has been widely used. In recent years, a contact charging type, especially a roller charging type using a conductive roller, has been used. Are widely used in terms of charging stability.

[0003] Contact charging has advantages such as low power and low ozone in comparison with corona chargers. However, in the corona charging method, the principle of charging is from the charging roller to the surface of the member to be charged. , And the generation of a very small amount of ozone and the deterioration of discharge on the surface of the member to be charged were inevitable.

In addition, a voltage higher than a required charging potential must be applied to the contact charging member, and charging can be performed only by applying only a voltage corresponding to the surface potential Vd of the member to be charged to the charging member. Has been desired.

In view of the above, there has been proposed a charging system by directly injecting charges into a member to be charged (Japanese Patent Application No. 4-158128).
No.). Since this charging method does not use a discharge phenomenon, the voltage required for charging is only the desired surface potential of the member to be charged, and no ozone is generated. Further, deterioration of the surface of the member to be charged due to the discharge can be avoided.

Examples of the contact charging member include a charging brush and a charging magnetic brush. From the viewpoint of charging properties and the like, a magnetic brush is an excellent charging member, and charge is injected into the charging brush to perform contact injection charging. Is considered to be an overall excellent charging method.

The photoreceptor used in the above-described charge injection type charging device needs a thin injection layer, and the injection layer is mainly made of a resin formed by three-dimensionally cross-linking to obtain film strength. is there. Examples of the resin to be formed into a film by three-dimensional crosslinking include acrylic resin, xylene resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, and butyral resin.

However, the above-described charge injection type charging device has a drawback that the charged carrier leaked from the magnetic brush of the charging member is pressed against the photoreceptor at the time of transfer, causing damage.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having a surface layer made of a resin formed by three-dimensional cross-linking, which is used in an injection charging process using a magnetic brush as a charger. Provided is an electrophotographic image forming apparatus and a process cartridge using an electrophotographic photoreceptor capable of suppressing damage caused by a charge carrier leaking from a magnetic brush being pressed during transfer, that is, suppressing an image defect due to the damage. It is in.

[0010]

According to the present invention, there is provided an electrophotographic photosensitive member of an electrophotographic image forming apparatus used in an injection charging process using a magnetic brush for a charger, wherein the surface layer of the electrophotographic photosensitive member is Relation between hardness H and indentation depth h in a surface film physical property test in a constant environment (22.5 ° C./50% RH) with respect to the surface layer mainly composed of a resin formed by three-dimensional cross-linking to form a film. Does not have an inflection point and the universal hardness value HU is 20
0 [N / mm ² ] or more, and the Young's modulus E in the film physical property test is 6.0 [GPa] or more and 9.0 [GP].
a] and the hardness value of the plastic deformation Hplast is HU
1.2 times or more of the work of elastic deformation We is the total work Wt
An electrophotographic apparatus having an electrophotographic photosensitive member that is 30% or more of the electrophotographic photosensitive member is provided.

Further, according to the present invention, a charging means, which is an injection charging process using a magnetic brush, and a resin formed by three-dimensionally cross-linking a surface layer of an electrophotographic photosensitive member are mainly used.
Constant environment (22.5 ° C / 50% R) for the surface layer
An electrophotograph in which a curve showing the relationship between the hardness H and the indentation depth in the surface film physical property test in H) has no inflection point and the universal hardness value HU is 200 [N / mm ² ] or more. Provided is a process cartridge which integrally supports a photosensitive member and is detachable from an electrophotographic image forming apparatus main body.

[0012]

Embodiments of the present invention will be described below in detail.

The surface film physical property test of the present invention can analyze the hardness of a thin film, a cured film, an organic film, and the like. In the measurement, a diamond indenter whose shape is a quadrangular pyramid and whose facing angle is defined at 136 ° is used. When used, when the set load is applied stepwise and pushed into the film, the depth of the indentation under the applied load is electrically detected and read, and the hardness H
Is expressed as the ratio of the test load divided by the surface area of the indentation produced by the test load. The universal hardness value HU is represented by a hardness value at the set maximum indentation depth.

In the surface layer made of resin formed by three-dimensionally cross-linking the electrophotographic photosensitive member, the universal hardness value H
If U is less than 200, the charge carrier leaking from the magnetic brush of the charger is easily pressed against the electrophotographic photoreceptor by being pressed by the transfer material during transfer.

In the following description, the functional number means the number of functional groups represented by the following formula (1) possessed by each binder.

[0016]

Embedded image

When the elasticity of the resin is insufficient, a phenomenon that the surface is cracked when the leaked charge carrier is pressed by the transfer material occurs. In other words, the curve showing the relationship between the hardness value H and the indentation depth h in the surface film physical property test shows a rapid change in hardness at the indentation depth h when the surface is cracked, as shown in FIG. Has the inflection point P shown. It is considered that such cracking of the surface leads to a deep wound.

The Young's modulus E in the surface film property test is as follows:
In the elastic region of the curve when the horizontal axis is the indentation depth (h) and the vertical axis is the load (L) shown in FIG.
As shown in FIG. 2, the load (A) at 60% of the maximum load Lmax and the load (B) at 95% of Lmax
It is represented by the slope of a straight line connecting the points. The Young's modulus E is 6.
If it is less than 0, the charged carrier leaked from the magnetic brush of the charger is easily damaged by being pressed against the transfer material during transfer. When a resin whose Young's modulus E is significantly higher than 9.0 is used, surface cracks and deep scratches occur as described above due to insufficient elasticity of the resin.

The plastic deformation, that is, the hardness value of the scratch, Hplast, is Hp in the surface film property test.
The value of last is correlated with the value of HU,
The larger the ratio of the value of blast, the greater the elasticity. Then, similarly to the above, when a resin having an Hplast value of less than 1.2 times the HU is used, the elasticity of the resin becomes insufficient,
It is considered that deep scratches due to surface cracks occur. The same applies when the work We of elastic deformation in the surface film physical property test is less than 30% of the total work Wt.

The photosensitive layer of the electrophotographic photosensitive member having the protective layer has a single layer or a laminated structure. In the case of a stacked structure, a charge generation layer that generates photocarriers and a charge transport layer in which carriers move are stacked. The surface layer may be formed on either the charge generation layer or the charge transport layer.

The single-layer photosensitive layer can have a thickness of 5 to 100 μm, more preferably 10 to 60 μm. The charge generation material and the charge transport material are contained in an amount of 20 to 80% by mass, and more preferably 30 to 70% by mass. In the laminated photoreceptor, the thickness of the charge generation layer is 0.001 to 6 μm, more preferably 0.01 to 2 μm. The amount of the charge generation material is 10 to 100% by mass, and more preferably 40 to 100% by mass. The thickness of the charge transport layer is 5 to 100 μm, and more preferably 10 to 60 μm. The amount of charge transport material is 2
It is 0 to 80% by mass, and more preferably 30 to 70% by mass.

Examples of the charge generating material used in the present invention include phthalocyanine pigments, polycyclic quinone pigments, azo pigments, perylene pigments, indigo pigments, quinacridone pigments, azurenium salt dyes, squarylium dyes, cyanine dyes, pyrylium dyes, and thiopyrylium dyes. Dyes, xanthene dyes, quinone imine dyes, triphenylmethane dyes, styryl dyes, selenium, selenium-tellurium, amorphous silicon, cadmium sulfide, and the like.

Examples of the charge transporting material used in the present invention include pyrene compounds, carbazole compounds, hydrazone compounds, N, N-dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, and styryl compounds. And stilbene compounds.

The conductive support used for the electrophotographic photoreceptor includes iron, copper, nickel, aluminum, titanium, tin,
Metals and alloys such as antimony, indium, lead, zinc, gold, and silver, or oxides, carbons, and conductive resins thereof can be used. The shapes include a cylindrical shape, a belt shape, and a sheet shape. The conductive material may be molded, but may be applied as a paint or may be deposited.

An undercoat layer may be provided between the conductive support and the photosensitive layer. The undercoat layer is mainly made of a binder resin, but may contain the conductive material or the acceptor.
As the binder resin for forming the undercoat layer, for example, polyester, polyurethane, polyarylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, polyamideimide, polysulfone, polyallylether, polyacetal, nylon, phenolic resin, Acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, butyral resin and the like can be mentioned.

As a method for producing the electrophotographic photosensitive member, methods such as vapor deposition and coating are used. For coating, a bar coater, knife coater, roll coater, attritor, spray, dip coating, electrostatic coating, powder coating, or the like is used.

FIG. 6 shows a schematic configuration of an electrophotographic apparatus using a process cartridge having an electrophotographic photosensitive member.

In FIG. 1, reference numeral 11 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is driven to rotate around a shaft 12 in a direction of an arrow at a predetermined peripheral speed. In the rotation process, the photosensitive member 11 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by the primary charging means 13, and then output from an exposure means (not shown) such as slit exposure or laser beam scanning exposure. It receives exposure light 14 that is emphasized and modulated according to a time-series electric digital image signal of desired image information. Thus, an electrostatic latent image corresponding to the target image information is sequentially formed on the peripheral surface of the photoconductor 11.

The formed electrostatic latent image is then developed by developing means 1
5 and the photosensitive member 1 is fed from a paper feeding unit (not shown).
The toner image formed and carried on the surface of the photoconductor 11 is sequentially transferred by the transfer unit 16 to the transfer material 17 taken out and fed in synchronization with the rotation of the photoconductor 11 between the transfer member 1 and the transfer unit 16. Will be done.

The transfer material 17 to which the toner image has been transferred is
After being separated from the photoreceptor surface and introduced into the image fixing means 18 and subjected to image fixing, the image is printed out of the apparatus as an image formed product (print, copy).

The surface of the photoreceptor 11 after the image transfer is cleaned and cleaned by removing the untransferred toner by a cleaning means 19, and further subjected to a charge removal process by pre-exposure light 20 from a pre-exposure means (not shown). Thereafter, it is repeatedly used for image formation. When the primary charging unit 23 is a contact charging unit using a magnetic brush or the like, the pre-exposure is not necessarily required.

In the present invention, of the above-described components such as the electrophotographic photosensitive member 11, the primary charging means 13, the developing means 15, and the cleaning means 19, a plurality of
And a process cartridge may be integrally connected and configured as a unit, and this process cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 13, the developing unit 15, and the cleaning unit 19 is integrally supported together with the photoreceptor 11 to form a cartridge, and is detachably attached to the apparatus main body using a guide unit 22 such as a rail of the apparatus main body. It can be a process cartridge.

[0033]

Next, the present invention will be described in more detail with reference to examples.

Example 1 100 parts by mass of conductive titanium oxide (coated with tin oxide, average primary particle size 0.4 μm), 10 parts by mass of a phenol resin precursor (resole type), 10 parts by mass of methanol, and 10 parts by mass of butanol Was sand-mill-dispersed, and the outer diameter was 30.6 mm and the length was 357.5 mm.
And then cured at 140 ° C., and a conductive layer having a volume resistance of 5 × 10 ⁹ Ωcm and a thickness of 20 μm was provided.

Next, 10 parts by mass of the following methoxymethylated nylon (degree of methoxymethylation: about 30%),

[0036]

Embedded image And 150 parts by mass of isopropanol were mixed and dissolved, followed by dip coating on the conductive layer to provide a subbing layer having a thickness of 1 μm.

Next, the Bragg angles (2θ ± 0.2 °) in the characteristic X-ray diffraction of CuKα are 9.0 °, 14.2 °,
Sand mill using 4 parts by mass of oxytitanium phthalocyanine having strong peaks at 23.9 ° and 27.1 °, 2 parts by mass of polyvinyl butyral (trade name: Eslec BM2, manufactured by Sekisui Chemical) and 60 parts by mass of cyclohexanone using φ1 mm glass beads After dispersion by an apparatus for 4 hours, 100 parts by mass of ethyl acetate was added to prepare a dispersion for a charge generation layer. This was applied by dip coating to provide a charge generation layer having a thickness of 0.3 μm.

Next, 10 parts by mass of the following triphenylamine:

[0039]

Embedded image Polycarbonate resin (bisphenol Z, molecular weight 20
000) 10 parts by mass, monochlorobenzene 50 parts by mass,
And 15 parts by mass of dichloromethane with stirring, followed by dip coating on the charge generation layer to provide a charge transport layer having a thickness of 20 μm.

Next, the following hexafunctional acrylic monomer 2
0 parts by mass,

[0041]

Embedded image And the following bifunctional acrylic monomer 5 parts by mass,

[0042]

Embedded image 50 parts by mass of ultrafine tin oxide particles having an average particle size of 40 nm before dispersion, 20 parts by mass of a polytetrafluoroethylene resin fine powder (average particle size of 0.18 μm), and 2-
18 parts by mass of methylthioxanthone and 150 parts by mass of ethanol were dispersed in a sand mill for 66 hours.

A film was formed by dip coating the above-prepared solution on the above-mentioned charge transporting layer, and 800 mW / c by a high-pressure mercury lamp.
the light intensity of the m ^2, for 60 seconds light curing, then 120
Drying with hot air at 2 ° C. for 2 hours provided a surface layer. At this time,
The thickness of the obtained surface layer was 3 μm. Thus, an electrophotographic photosensitive member A was produced.

Separately, an outer diameter of 30.6 mm and a length of 3
A surface layer having a thickness of 3 μm was provided on an aluminum cylinder having a thickness of 57.5 mm in the same manner as described above, and this was repeated three times in total, thereby obtaining a cylinder A having a surface layer having a thickness of 9 μm on the aluminum cylinder. '.
By providing a layer having a depth of about 10 times the indentation depth, the influence of the base at the time of measurement can be excluded.

The cylinder A 'thus produced was subjected to a surface film physical property test (Fisher Instruments H100V, manufactured by Fischer Instruments), and the universal hardness HU, Young's modulus E, and plastic deformation hardness of the surface layer were measured. The value Hplast, the work amount We of elastic deformation, and the total work amount Wt were obtained.

The measurement conditions were as follows: the maximum indentation depth was 1 μm, the measurement points in the depth direction were 60 points, and the measurement was performed in a constant environment (room temperature 22.5 ° C./humidity 50% RH).

As a result, the universal hardness HU is 250
[N / mm ² ], Young's modulus E was 8.3 [GPa], hardness value of plastic deformation Hplast was 350, and work We of elastic deformation was 35% of Wt.

(Example 2) Except that the amount of the hexafunctional acrylic monomer represented by the above formula (4) was 22.5 parts by mass and the amount of the bifunctional acrylic monomer represented by the formula (5) was 2.5 parts by mass. An electrophotographic photosensitive member B and a cylinder B 'were obtained in the same manner as in Example 1. The results of the surface film physical property test are HU
Was 283, E was 8.9, Hplast was 335, and We was 30% of Wt.

Example 3 An electrophotographic photosensitive member C and a cylinder C 'were produced in the same manner as in Example 1 except that the above polytetrafluoroethylene resin fine powder was changed to 15 parts by mass. As a result of the surface film physical property test, HU was 275, E
8.3, Hplast 400, We 35% of Wt
Met.

Example 4 An electrophotographic photosensitive member D and a cylinder D 'were produced in the same manner as in Example 1 except that the molecular weight of the polycarbonate resin was changed to 40,000. The result of the surface film physical property test was almost the same as the result of Example 1.

(Comparative Example 1) The injection charger was changed to a corona charger, and the copier was modified so that a printing test could be performed. A and A 'were used for the electrophotographic photosensitive member and the cylinder, respectively. Printing test.

Comparative Example 2 The procedure of Example 1 was repeated except that the hexafunctional acrylic monomer represented by the formula (4) was 25 parts by mass and the bifunctional acrylic monomer represented by the formula (5) was 0. Then, an electrophotographic photosensitive member E and a cylinder E 'were produced. As a result of the surface film physical property test, a curve indicating the relationship between hardness H and indentation depth h has an inflection point P, HU is 295, E is 9.6, Hplast is 328, and We is W.
t was 28%.

Comparative Example 3 The procedure of Example 1 was repeated except that the hexafunctional acrylic monomer represented by the formula (4) was changed to 0 and the bifunctional acrylic monomer represented by the formula (5) was changed to 25 parts by mass. Then, an electrophotographic photosensitive member F and a cylinder F 'were produced. As a result of the surface film physical property test, HU was 190, E was 7.1, Hplast was 520, and We was 51% of Wt.

(Comparative Example 4) An electrophotographic photosensitive member G and a cylinder G 'were produced in the same manner as in Example 1 except that the amount of the polytetrafluoroethylene resin powder was changed to 30 parts by mass. As a result of the surface film physical property test, HU was 195, E was 7.9, Hplast was 305, and We was 40% of Wt.

These electrophotographic photosensitive members A to G were incorporated into a Canon copier GP-55 modified so as to be capable of being charged by an injection charging method using a magnetic brush as a charger, and a copy durability test was conducted. Scratches on the photoreceptor were examined. Table 1 shows the results of the copy durability test. The result criteria of the surface film physical property test in Table 1 are as follows. …: HU ≧ 200, hardness H in surface film physical property test
The indentation depth h curve has no inflection point, 6.0 ≦ E ≦
9.0, Hplast ≧ 1.2 × HU, We / Wt ≧
Achieve 0.3. Δ: Among the above conditions, there are conditions that are not achieved slightly. ×: The above conditions are not achieved.

[0056]

[Table 1]

[0057]

As described above, according to the present invention,
In an electrophotographic photosensitive member of an electrophotographic image forming apparatus used in an injection charging process using a magnetic brush for a charger, a resin mainly formed of a resin in which a surface layer of the electrophotographic photosensitive member is three-dimensionally cross-linked to form a film. The curve showing the relationship between the hardness H and the indentation depth h in the surface film physical property test for the surface layer in a constant environment (22.5 ° C./50% RH) has no inflection point and is universal. Hardness value HU
Is 200 [N / mm ² ] or more, and the Young's modulus E in the film physical property test is 6.0 [GPa] or more and 9.0 or more.
[GPa] or less, and the plastic deformation hardness value Hplast
Is 1.2 times or more of HU, and the work We of elastic deformation is 30% or more of the total work Wt. It is possible to suppress scratches generated by pressing the carrier during transfer, that is, to suppress image defects due to scratches.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between hardness H and indentation depth h in a surface film physical property test for a surface layer of a conventional electrophotographic photoreceptor, where an inflection point P occurs.

FIG. 2 is a graph showing the relationship between hardness H and indentation depth h in a surface film physical property test for a surface layer of the electrophotographic photoreceptor of the present invention.

FIG. 3 is a graph showing the relationship between the load L and the indentation depth h in a surface film physical property test for the surface layer of the electrophotographic photoreceptor of the present invention.

4 shows a maximum load (Hmax) of 6 in the elastic region of FIG.
It is a graph which shows the straight line which connects two points of 0% and 95%.

FIG. 5 is an explanatory view showing a measuring method of a surface film physical property test.

FIG. 6 shows a schematic configuration of an electrophotographic apparatus using a process cartridge having an electrophotographic photosensitive member.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrophotographic photoreceptor 2 electrophotographic photoreceptor mounting table 3 indenter 4 movable table 5 microscope position 11 electrophotographic photoreceptor 12 shaft 13 charging means 14 exposure light 15 developing means 16 transfer means 17 transfer material 18 fixing means 19 cleaning means 20 Pre-exposure light 21 Process cartridge container 22 Guide means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Haruyuki Tsuji 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H003 BB11 CC04 2H068 AA03 AA04 AA08 BB06 BB20 BB57 BB59 FA27 FC01

Claims (5)

[Claims] An electrophotographic photosensitive member used in an injection charging process using a magnetic brush as a charger is mainly formed of a resin formed by three-dimensionally cross-linking a surface layer. C / 50% RH), the curve showing the relationship between the hardness H and the indentation depth of the indenter in the surface film physical property test has no inflection point, and the universal hardness value HU is 2
An electrophotographic image forming apparatus having an electrophotographic photosensitive member, wherein the electrophotographic image forming member has a density of not less than 00 [N / mm ² ]. 2. The electrophotographic image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member has a constant environment (22.5 ° C./50%).
RH), the Young's modulus E in the surface film physical property test is 6.
The electrophotographic image forming apparatus according to claim 1, wherein the electrophotographic image forming apparatus has a pressure of 0 to 9.0 [GPa]. 3. The electrophotographic image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member has a constant environment (22.5 ° C./50%).
The electrophotographic image forming apparatus according to claim 1 or 2, wherein a hardness value Hplast of plastic deformation in a surface film physical property test (RH) is 1.2 times or more of HU. 4. The electrophotographic image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member has a constant environment (22.5 ° C./50%).
The work We of elastic deformation in a surface film physical property test at RH) is 30% or more of the total work Wt.
An electrophotographic image forming apparatus according to any one of claims 1 to 3. 5. A charging means, which is an injection charging process using a magnetic brush, and a resin which is formed by three-dimensionally cross-linking the surface layer of the electrophotographic photoreceptor. In the surface film physical property test at 5 ° C./50% RH), the curve showing the relationship between the hardness H and the indentation depth does not have an inflection point, and the universal hardness value HU is 200 [N / mm ² ]. A process cartridge which integrally supports the above-described electrophotographic photosensitive member and is detachable from an electrophotographic image forming apparatus main body.