JP3246702B2 - Contact type charging member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type charging member used as a primary charging member, a transfer charging member, a charge removing member and the like in an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art An image forming apparatus such as an electronic copying machine or an electrostatic recording apparatus includes a step of uniformly charging a member to be charged.
As the charging method, a corona charging method is generally used. However, the corona charging method generates many products such as ozone, and requires additional means and a mechanism to cope with the problem. However, there is a problem that the size and cost are easily increased.

Therefore, recently, a contact charging method has been studied as a new charging method replacing the corona charging method, and some of them have been put to practical use.

In the contact charging method, a charging member to which a voltage is applied is brought into contact with a charged body with a predetermined pressing force to charge the charged body. Since the generation of ozone is greatly reduced as compared with the corona charging method, there is an advantage that the corona charging method does not require any additional means and mechanism. As the applied voltage, a superimposed voltage of a DC voltage and an AC voltage having a peak-to-peak voltage that is about twice the charging start voltage when the DC voltage is applied to the charging member is often used.

[0005] Further, the charging member needs to have a function of keeping the member to be charged at a predetermined potential, and it is important to control the electric resistance for this purpose within a certain range. Usually, a conductive pigment such as carbon black or tin oxide is used for the resistance control. For carbon black, the powder resistance is
10 ⁻² Ωcm, particle size of about 0.02 μm, tin oxide,
Powder resistance of titanium oxide etc. is 10 ¹ to 10 ² Ωc
m and a particle diameter of about 0.2 μm are used.

[0006]

However, the charging device using the charging member has the following problems. That is, the constituent materials of the surface layer of the charging member are a binder material and a conductive material. As the binder material, resins such as polyurethane and polyamide are often used from the viewpoint of economy and versatility.
Since these materials have a relatively high water absorption, they have disadvantages such as easy change of electrical characteristics in a use environment, relatively small contact angle with water, durability, and easy adhesion of toner, paper powder, and the like.

Further, the surface layer is generally formed by a dry film of a paint in which the above-mentioned fine particle-based conductive material is added to and dispersed in a binder material. However, the fine particle pigment easily undergoes re-agglomeration, sedimentation, and the like after the dispersion treatment, and has poor stability in the coating material, so that the distribution and density of the conductive material in the surface layer are likely to be uneven. Therefore, in an electrophotographic image forming apparatus using a contact-type charging member having such a constituent layer, when a predetermined potential is applied to a photoreceptor which is a member to be charged, minute charging unevenness is caused by a voltage on the photoreceptor. This may cause image defects. This is remarkable in a system to which only DC is applied. In order to improve this point, it is necessary to stabilize the dispersion by adding a dispersing aid and treating with a coupling agent. However, in the case of a dispersing aid such as a surfactant, photoreceptor contamination due to bleeding, coupling treatment, etc. Then, there were problems such as an increase in cost.

An object of the present invention is to solve the above-mentioned problems and to provide a contact charging member excellent in environmental stability, durability stability and charging uniformity.

[0009]

That is, the present invention relates to a charging member which contacts a member to be charged and charges by applying a voltage, the charging member comprising at least a conductive elastic layer and a member to be charged. A surface layer that is in contact with the conductive layer, the surface layer contains a fluorine-based binder material and a conductive pigment, and the conductive pigment has an average primary particle diameter of 0.5 μm or more and 5 μm or less, and A contact-type charging member having a resistance of 10 ⁻² Ωcm or more and 10 ⁶ Ωcm or less.

As the voltage applied to the charging member of the present invention, any of a DC voltage, a superimposed voltage of a DC voltage and an AC voltage, and the like can be used.

FIG. 1 shows a schematic configuration diagram of an example of an image forming apparatus (copier) to which the charging device according to the present invention is applied. In FIG. 1, reference numeral 1 denotes a photosensitive drum, 2 denotes a charging member in the form of a roller, 2a denotes a metal core, 2b denotes an elastic layer, 2c denotes a resistance control layer, 2d denotes a coating layer, 3 denotes a voltage application power source, and 4 denotes image exposure. A means 5, a developing means, a transfer means 6, a transfer material 7, and a cleaning means 8, respectively. Except for the charging member 2, the configuration and operation of each element are well known, and a detailed description thereof will be omitted.

FIG. 2 is a sectional view of an example of the charging member of the present invention. In FIG. 2, a charging member 2 is provided with a metal core 2 for applying a DC voltage or a superimposed voltage of a DC voltage and an AC voltage.
a, a conductive elastic layer 2-b for providing elasticity, a resistance control layer 2-c for controlling the resistance of the charging member, and a coating layer 2-d provided outside the resistance control layer as necessary. I have.
Therefore, the surface layer in the present invention may be either a resistance control layer or a coating layer.

[0013] PTFE, PF
Fluororesins such as A, FEP, PVDF, PCTFF and the like, and fluororubber can be mentioned, and they may be used alone or in combination of two or more. Most of these fluorine-based binder materials have no water absorption, and the environmental stability of a charging member using such a material is extremely good. Further, it has a feature that the contact angle with water is large, and contaminants such as paper powder and toner are hardly adhered.

Conductive material added to and dispersed in fluorine-based binder
The average primary particle diameter is 0.5 μm or more and 5 μm or less
Lower, preferably 0.5 μm or more and 3 μm or less, powder resistance
Is 10 ^-1Ωcm or more 10⁶Ωcm or less, preferably,
10⁰Ωcm or more 10^ThreeΩcm or less titanium oxide (acid
Surface treatment with tin oxide), metal acids such as tin oxide and zinc oxide
Pigment composed of oxide, conductive barium sulfate (by tin oxide
Pigment made of surface-treated, Sb-doped)
Metal oxide (surface treated with tin oxide, Sb-doped
), Spherical carbon materials, etc.
Alternatively, two or more kinds may be used in combination.

When the primary particle size is less than 0.5 μm, secondary aggregation after the dispersion treatment is liable to occur, and when the primary particle size is more than 5 μm, the image quality tends to be deteriorated due to pinhole leak and uneven charging.

When a filler having an extremely low powder resistance of less than 10.sup.- ² .OMEGA.cm, for example, a metal powder such as nickel, copper, or zinc is used, resistance unevenness due to a difference in resistance from a binder is large. If it exceeds 10 ⁶ Ωcm, the effect of addition is small and resistance adjustment becomes difficult.

The conductive elastic layer includes EPDM, NBR, S
Rubber materials such as BR, CR, silicone rubber, polystyrene, polyolefin, polyvinyl chloride, polyurethane,
Polyester, polyamide, thermoplastic elastomer (TPE) or the like can be used, but silicone rubber is suitable for improving durability in particular.

Silicone rubber is a polymer material whose main chain is a Si—O bond and has a large binding energy, so that its molecular structure is stable and its weather resistance and heat resistance are excellent, that is, it is hard to cause material deterioration. Therefore, stable characteristics can be maintained for a long time.

When a general-purpose rubber is used as a charging member for electrophotography such as SBR, the rubber material itself is deteriorated due to a small amount of generated ozone and a rise in temperature during durability, and the hardness of the rubber material itself is reduced. Some change over time.

As the above-mentioned silicone rubber, for example,
Thermal crosslinking silicone rubber such as methyl vinyl silicone rubber, methyl phenyl silicone rubber, and methyl vinyl phenyl silicone rubber, and addition polymerization or condensation polymerization silicone rubber at room temperature crosslinking can be used. Based on these silicone rubbers, if necessary, a predetermined amount of a conductivity-imparting agent such as carbon, a conductive metal oxide, a metal powder, and a solid electrolyte is added to adjust the resistance value to a required value.

The conductive elastic layer has a volume resistivity of 10 ^2.
Not less than 10 ¹⁰ Ωcm, preferably not less than 10 ^{3 and} 10 ⁹ Ωc
m or less is desirable. If it is less than 10 ² Ωcm, it may be difficult to control the resistance required for the charging member. Further, not only is it uneconomical since a large amount of a conductivity-imparting agent is required, but also the hardness of the base material can be extremely high even when, for example, a highly conductive carbon black is used.

On the other hand, if it exceeds 10 ¹⁰ Ωcm, it is difficult to obtain the resistance required for forming a charging member exhibiting good charging characteristics. The volume resistivity value is measured by the method described in ASTM D257-61.

JIS A hardness is 10 or more and 50 or less,
Preferably, it is 15 or more and 40 or less. If it is less than 10, the contact portion (nip portion) when it comes into contact with the member to be charged
Becomes large, and the required charging characteristics cannot be obtained.
When the value exceeds, the charging characteristics are good, but in addition to the generation of vibration noise, fusion of toner or the like to the photoreceptor is likely to occur, which may result in an image defect. JIS A hardness is
It is measured by the method described in JIS K6301.

Further, in order to maintain stable charging characteristics over a long period of time, it is important that the charging member material has low compression set. The charging member is stored and used in a state in which the charging member is brought into contact with the photoreceptor to be charged at a constant pressure. A material having a large compression set tends to cause an image defect due to permanent deformation of the charging member. Therefore, the compression set of the elastic body is 4
0% or less, preferably 30% or less is good. The compression set is measured and calculated by the method described in JIS K6301.

[0025]

Embodiments will be described below.

Example 1 Preparation of Compound for Elastic Layer (resistance control layer) 100 parts by weight of silicone rubber, 5 parts by weight of zinc oxide,
7 parts by weight of conductive carbon black and 20 parts by weight of industrial paraffin are sufficiently mixed and kneaded using a closed mixer, and then dicumyl peroxide 2 is opened with an open roll.
Parts by weight were added to make a compound. Preparation of paint for coating layer 100 parts by weight of fluoro rubber, conductive barium sulfate (surface treated with tin oxide, Sb-doped)
7 μm, powder resistance 10 ¹ Ωcm) 30 parts by weight, DM
F420 parts by weight were kneaded using a small bead mill to prepare a fluororubber paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the above coating material (fluororubber coating) was applied onto the charging member by dip coating, and dried by heating at 140 ° C. for 10 minutes to obtain a charging member having a coating layer having a thickness of 10 μm.

When the volume resistivity of the charging member was measured, it was 2.5 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 1 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of coating material for coating layer 100 parts by weight of polyamide resin, 30 parts by weight of conductive barium sulfate (surface treated with tin oxide, Sb-doped) (primary particle diameter of powder 0.7 μm, powder resistance 10 ¹ Ωcm),
100 parts by weight of methanol and 300 parts by weight of toluene were kneaded using a small bead mill to prepare a polyamide resin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (polyamide resin coating material) was dip-coated on the charging member,
By heating and drying for a period of time, a charging member having a coating layer having a thickness of 10 μm was obtained.

When the volume resistivity of the charging member was measured, it was 1.5 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

(Example 2) Preparation of compound for elastic layer (resistance control layer) Same as in Example 1. Preparation fluororesin 100 parts by weight of the coating layer paint, conductive titanium oxide (surface-treated with tin oxide) (primary particle diameter 0.5μm powder, powder resistance 10 ¹ [Omega] cm) 30 parts by weight, compact the DMF420 parts Using a bead mill, to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (fluororesin coating material) was applied onto the charging member by dip coating, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 10 μm.

When the volume resistivity of the charging member was measured, it was 2.8 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Example 3 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of paint for coating layer 100 parts by weight of fluororesin, tin oxide (primary particle size of powder)
2 μm, powder resistance 10 ² Ωcm) 40 parts by weight, DMF
420 parts by weight were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for a coating layer (fluorine resin coating material) was dip-coated on the charging member, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 12 μm.

When the volume resistivity of the charging member was measured, it was 2.2 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Example 4 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of coating material for coating layer 100 parts by weight of fluororesin, 30 parts by weight of zinc oxide (primary particle diameter of powder: 1 μm, powder resistance: 10 ¹ Ωcm), DMF
420 parts by weight were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (fluororesin paint) was applied onto the charging member by dip coating, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 11 μm.

When the volume resistivity of the charging member was measured, it was 1.8 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 2 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of coating material for coating layer 100 parts by weight of fluororesin, zinc powder (primary particle size of powder)
0.5 μm, powder resistance 10 ⁻⁵ Ωcm) 2 parts by weight, DMF
420 parts by weight were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (fluororesin coating material) was dip-coated on the charging member, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 12 μm. .

When the volume resistivity of the charging member was measured, it was 1.3 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

Example 5 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of paint for coating layer 100 parts by weight of fluororesin, conductive barium sulfate (surface treated with tin oxide, Sb-doped) (primary particle diameter of powder)
0.7 μm, powder resistance 10 ¹ Ωcm) 30 parts by weight, D
420 parts by weight of MF were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (fluororesin coating material) was applied onto the charging member by dip coating, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 11 μm. .

When the volume resistivity of the charging member was measured, it was 2.8 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 3 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of coating material for coating layer 100 parts by weight of fluororesin, conductive titanium oxide (surface treated with tin oxide) (primary particle diameter of powder 0.04 μm,
30 parts by weight of powder resistance (10 ¹ Ωcm) and 420 parts by weight of DMF were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

The coating material for the coating layer (fluororesin coating material) was dip-coated on the charging member, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 10 μm. .

When the volume resistivity of the charging member was measured, it was 1.8 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

Comparative Example 4 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of paint for coating layer 100 parts by weight of fluororesin, conductive barium sulfate (surface treated with tin oxide, Sb-doped) (primary particle diameter of powder)
7 μm, powder resistance 10 ¹ Ωcm) 30 parts by weight, DM
F 420 parts by weight is kneaded using a small bead mill,
A fluororesin paint was prepared. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

The coating material for the coating layer (fluororesin coating material) was dip-coated on the charging member, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 10 μm. .

When the volume resistivity of the charging member was measured, it was 2.0 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

(Example 6) Preparation of compound for elastic layer (resistance control layer) Same as in Example 1. Preparation of coating for coating layer 100 parts by weight of fluororesin, ferrite: Cu-Mg-
Zn (Powder primary particle diameter 1 μm, powder resistance 10 ⁶ Ω
cm) 200 parts by weight and 420 parts by weight of DMF were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (fluororesin coating material) was applied onto the charging member by dip coating, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 12 μm. .

When the volume resistivity of the charging member was measured, it was 3.2 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 5 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of coating material for coating layer 100 parts by weight of fluororesin, carbon black (primary particle diameter of powder: 0.02 μm, powder resistance: 10 ⁻² Ωcm)
4 parts by weight and 420 parts by weight of DMF were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for a coating layer (fluororesin coating material) was applied onto the charging member by dip coating, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 10 μm. .

When the volume resistivity of the charging member was measured, it was 1.1 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

Example 7 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of coating material for coating layer 100 parts by weight of fluororesin, 4 parts by weight of carbon (powder primary particle diameter 5 μm, powder resistance 10 ⁻² Ωcm), DMF
420 parts by weight were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for the coating layer (fluororesin coating material) was dip-coated on the charging member, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 12 μm. .

When the volume resistivity of the charging member was measured, it was 2.4 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 6 Preparation of Compound for Elastic Layer (Resistance Control Layer) Same as in Example 1. Preparation of paint for coating layer 100 parts by weight of fluororesin, ferrite: Cu-Zn
(Powder primary particle diameter 1μm, powder resistance 10 ⁷ Ωc
m) 300 parts by weight and 420 parts by weight of DMF were kneaded using a small bead mill to prepare a fluororesin paint. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.

Next, the coating material for a coating layer (fluororesin paint) was applied onto the charging member by dip coating, and dried by heating at 180 ° C. for 30 minutes to obtain a charging member having a coating layer having a thickness of 11 μm. .

When the volume resistivity of the charging member was measured, it was 3.4 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

Example 8 Preparation of Compound for Elastic Layer Same as Example 1. Preparation of paint for resistance control layer Hydrine rubber 100 parts by weight, ethylene thiourea 2
Parts, lead oxide 5 parts by weight, 2.5 parts by weight of fatty acid metal salts, titanium oxide (surface-treated with tin oxide) (average primary particle diameter of 0.02 [mu] m, the powder resistance 10 ¹ [Omega] cm) 60 parts by weight to open roll The mixture was kneaded for 20 minutes while being cooled to produce a compound. This compound was diluted and dissolved with toluene to prepare a hydrin rubber coating having a solid content of 5%. Preparation of coating material for coating layer Same as in Example 1. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.
Next, the above-mentioned paint for a resistance control layer (hydrin rubber paint) was applied onto the roller by dip coating, and dried by heating at 160 ° C. for 1 hour to obtain a charging member having a 105 μm-thick resistance control layer. Next, the coating material for the coating layer (fluororubber coating material) was similarly immersed and applied onto the charging member, and at 140 ° C.
By heating and drying for 10 minutes, a charging member having a coating layer having a thickness of 10 μm was obtained.

When the volume resistivity of the charging member was measured, it was 1.4 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 7 Preparation of Compound for Elastic Layer Same as Example 1. Preparation of paint for resistance control layer Same as in Example 8. Preparation of coating material for coating layer Same as Comparative Example 3. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.
Next, the above-mentioned paint for a resistance control layer (hydrin rubber paint) was applied onto the roller by dip coating, and dried by heating at 160 ° C. for 1 hour to obtain a charging member having a 100 μm-thick resistance control layer. Next, the coating material for the coating layer (fluororesin coating material) was similarly immersed and applied onto the charging member,
By heating and drying for 10 minutes, a charging member having a coating layer having a thickness of 10 μm was obtained.

When the volume resistivity of the charging member was measured, it was 2.1 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 2 shows the results.

Example 9 Preparation of Compound for Elastic Layer Same as Example 1. Preparation of paint for resistance control layer Same as in Example 8. Preparation of coating material for coating layer Same as in Example 2. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.
Next, the above-mentioned paint for a resistance control layer (hydrin rubber paint) was applied onto the roller by dip coating, and dried by heating at 160 ° C. for 1 hour to obtain a charging member having a 115 μm-thick resistance control layer. Next, the coating material for the coating layer (fluororesin coating material) was similarly immersed and applied onto the charging member.
By heating and drying for 30 minutes, a charging member having a coating layer having a thickness of 12 μm was obtained.

When the volume resistivity of the charging member was measured, it was 2.4 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Example 10 Preparation of Compound for Elastic Layer Same as Example 1. Preparation of paint for resistance control layer Same as in Example 8. Preparation of paint for coating layer Same as in Example 6. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3
A silicone rubber roller having an mm elastic layer was obtained.
Next, the above-mentioned paint for a resistance control layer (hydrin rubber paint) was applied onto the roller by dip coating, and dried by heating at 160 ° C. for 1 hour to obtain a charging member having a 100 μm-thick resistance control layer. Next, the coating material for the coating layer (fluororesin coating material) was similarly immersed and applied onto the charging member.
By heating and drying for 30 minutes, a charging member having a coating layer having a thickness of 11 μm was obtained.

When the volume resistivity of the charging member was measured, it was 3.0 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Example 11 Preparation of Compound for Elastic Layer Same as Example 1. Preparation of paint for resistance control layer Same as in Example 8. Preparation of coating material for coating layer Same as in Example 7. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.
Next, the above-mentioned paint for a resistance control layer (hydrin rubber paint) was dip-coated on this roller, and dried by heating at 160 ° C. for 1 hour to obtain a charging member having a 110 μm-thick resistance control layer. Next, the coating material for the coating layer (fluororesin coating material) was similarly immersed and applied onto the charging member.
By heating and drying for 30 minutes, a charging member having a coating layer having a thickness of 10 μm was obtained.

When the volume resistivity of the charging member was measured, it was 1.7 × 10 ⁶ Ωcm.

This charging member is connected to an analog copying machine (NP20
20 Canon Inc.) attached to the primary charger position,
23 ° C, 5% RH, 23 ° C, 60% RH, 30 ° C, 80
% RH under each bias environment of -1800V _DC ,
An initial image evaluation and a durability test, and a leak test were performed in an environment of 30 ° C. and 80% RH. Table 1 shows the results.

Comparative Example 8 Preparation of Compound for Elastic Layer Same as Example 1. Preparation of resistance control layer Same as in Example 8. Preparation of coating material for coating layer Same as Comparative Example 1. Production and Evaluation of Charging Member First, the above-mentioned compound for an elastic layer was heated and vulcanized at 150 ° C. for 15 minutes on a stainless steel core having a diameter of 10 mm to obtain a thickness of 3 mm.
A silicone rubber roller having an mm elastic layer was obtained.
Next, the above-mentioned paint for a resistance control layer (hydrin rubber paint) was applied onto the roller by dip coating, and dried by heating at 160 ° C. for 1 hour to obtain a charging member having a 105 μm-thick resistance control layer. Next, the coating material for the coating layer (polyamide resin coating material) was similarly immersed and coated on the charging member at 120 ° C.
By heating and drying for 2 hours, a charging member having a coating layer having a thickness of 12 μm was obtained.

When the volume resistivity of the charging member was measured, it was 2.5 × 10 ⁶ Ωcm. This charging member was attached to the primary charger position of an analog copying machine (NP2020, manufactured by Canon Inc.), and was set at 23 ° C., 5% RH, 23 ° C., 6
-1800 in each environment of 0% RH, 30 ° C, and 80% RH
Initial image evaluation and durability test under bias condition of _VDC , 3
A leak test was performed in an environment of 0 ° C. and 80% RH. Table 2 shows the results.

(Example 12) The charging member produced in Example 8 was replaced with an analog copying machine (NP2020 Canon Inc.)
At the bias condition of DC voltage -750V AC voltage 1500Vpp, 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 1 shows the results.

(Comparative Example 9) The charging member produced in Comparative Example 7 was replaced with an analog copying machine (NP2020, manufactured by Canon Inc.).
At the primary charger position, DC voltage -750V, AC voltage 1500Vpp, under bias condition of 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 2 shows the results.

(Example 13) The charging member produced in Example 9 was replaced with an analog copying machine (NP2020 Canon Inc.)
At the bias condition of DC voltage -750V AC voltage 1500Vpp, 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 1 shows the results.

(Example 14) The charging member prepared in Example 3 was replaced with an analog copying machine (NP2020 Canon Inc.)
At the bias condition of DC voltage -750V AC voltage 1500Vpp, 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 1 shows the results.

Comparative Example 10 The charging member produced in Comparative Example 1 was replaced with an analog copying machine (NP2020 Canon Inc.)
At the bias condition of DC voltage -750V AC voltage 1500Vpp, 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 2 shows the results.

(Embodiment 15) An analog copying machine (NP2020 Canon Inc.) was used for the charging member produced in Embodiment 6.
At the bias condition of DC voltage -750V AC voltage 1500Vpp, 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 1 shows the results.

(Example 16) The charging member prepared in Example 7 was replaced with an analog copying machine (NP2020 Canon Inc.)
At the bias condition of DC voltage -750V AC voltage 1500Vpp, 23 ° C, 5% RH, 23 ° C, 60%
The initial image evaluation and the durability test were performed in each environment of RH, 30 ° C., and 80% RH, and the leak test was performed in the environment of 30 ° C., 80% RH. Table 1 shows the results.

[0102]

[Table 1]

[0103]

[Table 2]

[0104]

As described above, the present invention is directed to a charging member which contacts a member to be charged and applies a voltage to perform charging, the charging member comprising at least a conductive elastic layer and a member to be charged. The surface layer contains a fluorine-based binder material and a conductive pigment, and the conductive pigment has an average primary particle diameter of 0.5 μm or more and 5 μm or less and a powder resistance. When used in an electrophotographic image forming apparatus, by using a contact-type charging member characterized by having a contact resistance of 10 ⁻² Ωcm or more and 10 ⁶ Ω or less, environmental stability, durability stability, and charging uniformity Demonstrates excellent characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an example of an image forming apparatus using a charging member according to the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a charging member according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 2a Core metal 2b Elastic layer 2c Resistance control layer 2d Coating layer 3 Voltage application power supply 4 Image exposure means 5 Developing means 6 Transfer means 7 Transfer material 8 Cleaning means

Claims (15)

(57) [Claims] 1. A charging member that contacts a member to be charged and charges by applying a voltage, wherein the charging member has at least a conductive elastic layer and a surface layer that contacts the member to be charged. The surface layer contains a fluorine-containing binder material and a conductive pigment, and the conductive pigment has an average primary particle diameter of 0.5 μm or more and 5 μm or more.
Less than or equal to 10 ⁻² Ωcm and 10 ⁶ Ωcm
A contact-type charging member characterized by the following. 2. The contact-type charging member according to claim 1, wherein the fluorine-based binder is a fluororesin obtained by graft-polymerizing a crystalline fluororesin on a fluororubber. 3. The contact-type charging member according to claim 1, wherein said conductive elastic layer is made of silicone rubber. 4. The elastic layer has a volume resistivity of 10 ² Ω.
2. The contact-type charging member according to claim 1, wherein the thickness is from ¹⁰ cm to 10 ¹⁰ Ωcm. 5. The contact-type charging member according to claim 1, wherein the conductive pigment is titanium oxide, tin oxide or zinc oxide surface-treated with tin oxide. 6. The contact-type charging member according to claim 1, wherein the conductive pigment is Sb-doped conductive barium sulfate surface-treated with tin oxide. 7. The contact-type charging member according to claim 1, wherein the conductive pigment is a Sb-doped conductive composite metal oxide surface-treated with tin oxide. 8. The contact-type charging member according to claim 1, wherein the conductive pigment is a spherical carbon material. 9. The contact-type charging member according to claim 1, wherein the conductive pigment is ferrite. 10. The contact-type charging member according to claim 1, wherein the applied voltage is an oscillating voltage. 11. The contact-type charging member according to claim 10, wherein the oscillating voltage is a superimposed voltage of an AC voltage and a DC voltage. 12. The contact-type charging member according to claim 1, wherein the contact-type charging member is used under a condition that the applied voltage is a DC voltage. 13. The contact-type charging member according to claim 1, which is a primary charging member. 14. The contact-type charging member according to claim 1, which is a transfer charging member. 15. The contact-type charging member according to claim 1, which is a charging member for static elimination charging.