JPH08101563A - Electrifying member - Google Patents

Abstract

PURPOSE: To suppress the sticking of a toner, etc., to the surface of the semiconductive elastic layer of an electrifying member and to improve the durability of the member by forming a surface layer of a resin consisting essentially of polyester polyol and polyisocyanate as polymers on the elastic layer. CONSTITUTION: This electrifying member is a roll-shaped member and consists of an electrically conductive substrate 101 having the shape of a core metal, a semiconductive elastic layer 102 disposed around the substrate 101 and a surface layer 103 formed on the peripheral surface of the elastic layer 102. The endless belt-shaped elastic layer 102 is made of epichlorohydrin rubber and the surface layer 103 is made of a hardened film consisting of polyester polyol and a relatively excess of polyisocyanate. The polyester polyol is a polyrmer obtd. by bringing polycarboxylic acid and polyol into a condensation reaction and having ester bonds and hydroxyl groups in each molecule and forms a coating film having superior nonstickiness and flexibility by urethane crosslinking with polyisocyanate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member used in an electrophotographic apparatus, and more particularly to a charging member used for primary charging and transfer charging in an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, as a charging process in an electrophotographic process, a corona discharge method has been widely used in which charging is performed by a corona generated by applying a high voltage (DC 6 to 8 KV) to a metal wire. However, in this corona discharge method, when corona is generated, corona products such as ozone and nitrogen oxides deteriorate the surface of the photoconductor to cause image blurring and deterioration, and wire stains adversely affect image quality. was there.

On the other hand, a contact charging system in which a voltage is applied while the photosensitive drum is in contact with the charging member to charge the surface of the photosensitive member has been put into practical use. This charging method has the advantages of lowering the voltage of the power supply and generating less ozone, but it is considerably inferior to the corona discharge method in terms of uniformity of charging.

In order to improve the uniformity of the charging, for example, in the "contact charging method" disclosed in Japanese Patent Laid-Open No. 63-149668, the charging start voltage (Vth) when a DC voltage is applied. It is disclosed that the uniformity of charging can be considerably improved by superimposing an AC voltage having a peak-to-peak voltage that is more than twice the peak voltage.

Further, for example, Japanese Patent Laid-Open No. 58-194061.
In the "roller charging device" disclosed in Japanese Patent Laid-Open Publication No.
It is disclosed that the uniformity of charging can be considerably improved by providing a cleaning element and coating the surface of the conductive elastic body with a non-adhesive coating.

However, in Japanese Patent Laid-Open No. 63-149668, the charging start voltage (Vth) when a DC voltage is applied.
In order to superimpose a high-voltage AC voltage that is more than twice the peak-to-peak voltage, an AC power supply is required in addition to the DC power supply,
This increases the cost of the device itself. Furthermore, by consuming a large amount of alternating current, the amount of ozone generated increases,
As a result, there is a problem that the charging member and the photoconductor are deteriorated.

Further, in JP-A-58-194061, the surface layer coated with a non-adhesive coating cannot sufficiently achieve the non-adhesiveness and the film strength of the coating. Due to the non-adhesiveness of the coating and the strength of the coating, a large amount of toner adheres to the surface layer, which causes the deterioration of the durability of the charging roller.

In the conventional charging member, when the charging member only applies a DC voltage, uneven charging occurs when the elastic layer of the charging member has carbon black dispersed in synthetic rubber. That is, the charging unevenness of the conventional charging member is due to electrical non-uniformity of the conductive layer due to poor dispersion of carbon black / synthetic rubber. However, the nonuniform charging of the charging member can be eliminated by replacing the carbon black / synthetic rubber with a semiconductive polar rubber (for example, epichlorohydrin rubber).

The polar rubber will be described below.
Polar rubber (or polar rubber) is a generic term for rubbers having a polar group in a polymer, such as epichlorohydrin rubber, nitrile rubber, urethane rubber, chloroprene rubber,
Acrylic rubber and the like contain polar groups such as -CL, -CN, -NH, and -COO. Against this,
Rubbers that do not contain polar groups such as natural rubber, styrene-butadiene rubber, and butyl rubber are called non-polar rubbers.

Further, when the charging member only applies a DC voltage, the withstand voltage of the charging member becomes a problem. However, by using epichlorohydrin in the elastic layer, the conductive elastic layer of the conventional carbon black / synthetic rubber system is formed. In comparison, the withstand voltage is significantly improved.

[0011]

However, according to the charging member using the conventional epichlorohydrin rubber for the semiconductive elastic layer, when the charging member is used for a long period of time, toner and paper powder adhere to the surface of the charging member. Or it will stick. As a result, the electric resistance value of the charging member increases,
There is a problem that the charging performance is lowered. That is,
There is a problem in that residual toner particles that have passed through the cleaning and remain on the photoconductor adhere to the surface of the charging member that is in contact with the photoconductor and have an adverse effect.

The present invention has been made in view of the above, and it is an object of the present invention to improve the durability of a charging member by suppressing adhesion of toner or the like to the surface of the semiconductive elastic layer. .

[0013]

In order to achieve the above object, the charging member according to claim 1 is a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support. A surface layer made of a resin mainly composed of a polymer of polyester polyol and polyisocyanate is provided on the semiconductive elastic layer.

Further, the charging member according to claim 2 is a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein a fluoropolyol and a fluoropolyol are formed on the semiconductive elastic layer. A surface layer made of a resin mainly composed of a polymer of polyisocyanate is provided.

Further, the charging member according to claim 3 is a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein a polybutadiene polyol is added on the semiconductive elastic layer. A surface layer made of a resin mainly composed of a polymer of polyisocyanate is provided.

Further, the charging member according to claim 4 is a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein a silicone-modified polyol is formed on the semiconductive elastic layer. And a surface layer made of a resin whose main component is a polymer of polyisocyanate.

In the charging member according to the fifth aspect, the NCO / OH molar ratio of the polyol of the resin forming the surface layer and the polyisocyanate is 1.0 / 1.0 to 1.8.
/1.0.

[0018]

In the charging member according to the present invention (claim 1), a surface layer made of a resin mainly composed of a polymer of polyester polyol and polyisocyanate is provided on the semiconductive elastic layer. This suppresses adhesion of residual toner and the like on the surface of the image bearing member such as the photosensitive drum which is the member to be charged.

A charging member according to the present invention (claim 2)
By providing a surface layer made of a resin mainly composed of a polymer of fluoropolyol and polyisocyanate on the semiconductive elastic layer, the surface layer enables the image bearing of a photoreceptor drum or the like to be charged. It suppresses the adhesion of residual toner on the body surface.

A charging member according to the present invention (claim 3)
By providing a surface layer made of a resin mainly composed of a polymer of polybutadiene polyol and polyisocyanate on the semiconductive elastic layer, the surface layer enables the image bearing of a photosensitive drum or the like to be charged. It suppresses the adhesion of residual toner on the body surface.

A charging member according to the present invention (claim 4)
By providing a surface layer made of a resin mainly composed of a polymer of silicone-modified polyol and polyisocyanate on the semiconductive elastic layer, the surface layer allows an image of a photoreceptor drum or the like to be charged. It suppresses adhesion of residual toner on the surface of the carrier.

A charging member according to the present invention (claim 5)
Has an NCO / OH molar ratio of the polyol of the resin forming the surface layer to the polyisocyanate of 1.0 / 1.
By being 0 to 1.8 / 1.0, the non-adhesiveness of the surface of the charging member is improved.

[0023]

EXAMPLES Hereinafter, the charging member of the present invention will be described in detail with reference to the drawings in the order of the configuration of a charging device to which the charging member of the present invention is applied. To do.

Shape of Charging Member of the Present Invention First, an example of the shape of the charging member of the present invention will be described. The charging member of the present invention has a roller shape as shown in FIG. 1, and includes a conductive support 101 in the form of a core metal, a semiconductive elastic layer 102 provided around the conductive support 101, and a semiconductive elastic layer. The surface layer 103 is formed on the outer peripheral surface of the elastic layer 102.

Further, as shown in FIG. 2, a conductive support 101 in the form of a flat plate may be composed of a surface layer 103 formed on the outer surface of the semiconductive elastic layer 102. A roller shape is preferable in terms of uniform charging.

Further, the charging member of the present invention comprises a conductive support member 101 having a pair of parallel axes as shown in FIG.
Alternatively, the endless belt-shaped semiconductive elastic layer 102 may be provided. Further, the surface layer 103 may be formed on the outer peripheral surface of the semiconductive elastic layer 102.

Endless belt-like semiconductive elastic layer 10
2 is epichlorohydrin rubber, and surface layer 103
Is composed of a cured film of polyol and relatively excess polyisocyanate. The semi-conductive elastic layer 1
02 and the surface layer 103, a layer such as an adhesive layer for improving the adhesiveness between the layers may be provided. As the adhesive layer, for example, in the case of a roller shape, the conductive support 10 is used.
1 may be treated with a conductive primer such as synthetic rubber containing a conductive substance such as carbon black.

As the conductive support 101, a metal such as iron, stainless steel, or aluminum, or a conductive resin such as a carbon black dispersed resin or a metal particle dispersed resin can be used, and the shape thereof is as described above. A rod shape or a plate shape is used.

Good results are obtained when the volume resistance of the semiconductive elastic layer 102 is in the range of 10 ⁷ to 10 ¹⁰ Ω · cm. Therefore, polar rubbers such as epichlorohydrin rubber, nitrile rubber, urethane rubber, chloroprene rubber, and acrylic rubber can be used as the material, but among them, the electric resistance of the rubber itself is relatively low and the environmental stability is further improved. From the point that it is excellent in
Epichlorohydrin gum is preferred.

Further, epichlorohydrin rubber is a homopolymer of epichlorohydrin rubber (abbreviation: CO), a copolymer of epichlorohydrin and ethylene oxide (abbreviation: CO).
ECO), a copolymer of epichlorohydrin and allyl glycidyl ether (abbreviation: GCO), and a ternary copolymer of epichlorohydrin, ethylene oxide and allyl glycidyl ether (abbreviation: GECO), among which electrical resistance is relatively high. GEC in terms of lowness and environmental stability
O and ECO are preferred.

The layer thickness of the semiconductive elastic layer 102 is 0.
Good results are obtained in the range of 5 to 10 mm. For example, the volume resistance of the semiconductive elastic layer 102 is 10 ⁷ Ω · c.
If the thickness is less than m and the layer thickness is less than 0.5 mm, dielectric breakdown of the photoconductor, unstable charging, image unevenness, and pinholes on the photoconductor,
The electric current concentrates on that portion, and the leakage easily occurs, and as a result, horizontal stripes appear on the image.

Further, for example, when the volume resistance of the semiconductive elastic layer 102 is higher than 10 ¹⁰ Ω · cm and the layer thickness is thicker than 10 mm, it becomes difficult to charge, and it becomes necessary to apply a higher voltage, and the charging efficiency becomes higher. Will start to decline. A surface layer 103 is formed as a non-adhesive film having a thickness of 0.5 to 10 μm on the outer peripheral surface of the semiconductive elastic layer 102. This is to prevent toner from adhering to the surface of the charging member and maintain good charging characteristics for a long period of time.

Polyols such as polyester polyols, fluorine polyols, polybutadiene polyols and silicone modified polyols and a relatively excess amount of polyisocyanate (provided that the NCO / OH molar ratio is 1.0 / 1.0 to
The coating film (surface layer 103 of the present invention) having a high hardness and flexibility, which has been subjected to a curing reaction at 1.8 / 1.0), has excellent non-adhesiveness to toner and the like, and also has durability and environment resistance. It has excellent characteristics.

Further, this film (the surface layer 103 of the present invention)
Has a relatively high electric resistance of 10 ¹¹ to 10 ¹² Ω · cm. Therefore, in order to make the direct-current voltage applied to the conductive support of the charging member act efficiently, the surface layer thickness is 0.5 to 1
It is preferably in the range of 0 μm.

The polyester polyol used for the surface layer 103 is a film obtained by condensation reaction of polyvalent carboxylic acid and polyhydric alcohol, and is a polymer having ester bond and hydroxyl group in the molecule and formed by urethane crosslinking with polyisocyanate. Has excellent non-adhesiveness and flexibility.

In the fluoropolyol, a fluoroolefin having good environment resistance and non-adhesiveness is regularly copolymerized with a plurality of alkyl vinyl ethers. The copolymerized alkyl vinyl ether has an excellent flexibility function.

The polybutadiene polyol is a butadiene copolymer and is a liquid homo or copolymer containing an OH group at the terminal. There are two types of copolymers, styrene and acrylonitrile, and the homopolymer is preferable from the viewpoint of flexibility.

Since this type of polyol is mainly composed of a non-polar polyolefin skeleton, the polyurethane synthesized from it has good hydrolysis resistance, in other words, good environmental resistance. As shown in Chemical formula 1, the silicone-modified polyol is a silicone-modified polyether polyol and has excellent non-adhesiveness, environment resistance, and flexibility.

[0039]

Embedded image

As the polyisocyanate used together with the polyol, an isocyanate compound such as hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate or a blocked isocyanate compound is used.

Configuration Example of Charging Device Using Charging Member of the Present Invention Next, the configuration of the charging device of the present invention using the charging member will be described with reference to FIG. This charging device includes a charging member 40 on the peripheral surface of a drum-shaped electrophotographic photosensitive member 407.
1, an image exposure device (not shown), a developing device 403, a transfer charging device 404, a cleaning device 405, and a pre-exposure device (not shown) are arranged. In the figure, reference numeral 402 denotes exposure light emitted from the image exposure device, and 406
Is the pre-exposure light of the pre-exposure device, and 408 is the transferred member such as paper.

For example, an electrophotographic photosensitive member 40 such as OPC
A voltage (for example, DC-1500V) is externally applied to the charging member 401 arranged in contact with the surface of the electrophotographic photosensitive member 407 to charge the surface of the electrophotographic photosensitive member 407, and the image on the document is transferred to the photosensitive member by the image exposure device. Imagewise exposed to form an electrostatic latent image.

Next, the developer in the developing device 403 is attached to the photoconductor to develop the electrostatic latent image on the photoconductor, and the developer on the photoconductor is transferred to the paper by the transfer charging device 404. And the like, and the cleaning device 405 collects the developer remaining on the photoconductor without being transferred to the paper at the time of transfer. Further, when residual charges remain on the photoconductor, it is better to remove the residual charges on the photoconductor by the pre-exposure device before performing the primary charging.

When the charging member of the present invention is used for transfer charging, it can be applied to, for example, an electrophotographic apparatus as shown in FIG. In this apparatus, a charging corona charger 501, an image exposing device (not shown), a developing device 403, a transfer charging member 502, a cleaning device 405, a pre-exposure device (not shown) are provided on the peripheral surface of the electrophotographic photosensitive member 407. No) is arranged. In the figure, reference numeral 402 is the exposure light emitted from the image exposure apparatus, 406 is the pre-exposure light of the pre-exposure apparatus, and 4 is the exposure light.
Reference numeral 08 denotes a transfer target member such as paper.

For example, an electrophotographic photosensitive member 40 such as OPC
A voltage (for example, direct current -500 to -1000 V) is applied to the transfer charging member 502 arranged in contact with the electrophotographic photosensitive member 7 to transfer the developer on the electrophotographic photosensitive member to a transfer target member such as paper. .

Further, the semiconductive elastic layer 102 relating to the charging member 401 of the present invention is preferably flame-retardant because it is used for supporting the electrode, and particularly UL-4.
In 78 (standard for information processing and office equipment), it is preferable to have flame retardancy of 94 HB or more of UL-94 (flammability test of plastic materials for parts of equipment).

Examples 1 to 12 Hereinafter, regarding the charging member of the present invention, [Example 1], [Example 2], [Example 3], [Example 4], [Example 5], [Example 5], Example 6], [Example 7], [Example 8],
[Embodiment 9], [Embodiment 10], [Embodiment 11], and [Embodiment 12] will be described in this order with reference to the drawings.

[Embodiment 1] In Embodiment 1, the charging member is prepared by the following method. First, as the conductive support 101, a φ8 mm stainless steel core is used. Next, the semiconductive elastic layer 102 is made of the following compound.

GECO-based epichlorohydrin rubber (Epichroma CG: made by Daiso) 100 superposed portion calcium carbonate (Whiten SO: made by Shiraishi calcium) 15 superposed portion tetramethylthiuram disulfide (Nocceller TT: made by Ouchi Shinko Chemical Co., Ltd.) 1 superposed portion sulfur ( Salfax PMC: Tsurumi Chemical Co., Ltd. 0.25 superposition part Antimony trioxide (Atox S: made by Nihon concentrate) 7 superposition part Aluminum hydroxide (Hidilite H42S: Showa Denko) 25 superposition part Chlorinated paraffin (Empala K- 65: made by Ajinomoto) 15 superposition part

The above compound was sufficiently kneaded with a two-roll mill, and was then molded on a φ8 mm stainless steel core by a die molding method (vulcanization: 150 ° C. × 15 minutes, secondary vulcanization: 155 ° C. × 7 hours). ), A semiconductive elastic layer 102 of a roller-shaped charging member having an outer diameter of 14 mm was provided. The volume resistance of this elastic roller is 5
× 10 ⁷ Ω · cm, roller rubber hardness 38 degrees (Jis
It was A).

The volume resistance of the elastic roller was measured by leaving the roller in an environment of 20 ° C. and 60% for 16 hours and then measuring 10 mm.
Wound copper foil tape (No. 1245: 3M) is wound around the roller circumference to form an electrode, and a DC voltage of 10 is applied between the core metal and the electrode.
00V was applied, the current value 1 minute after that was measured, and the resistance value between the core metal and the electrode was measured.

The rubber hardness of the roller is JisK630.
Using the hardness meter JisA described in 1, the pressure was measured perpendicularly to the central axis direction of the roller.

Next, a method of forming the surface layer 103 on the semiconductive elastic layer 102 of the roller will be described. First,
The surface layer treatment liquid was adjusted as follows.

Polyester polyol (Eurac C-230U [OH value: 49 mg KOH / g]: manufactured by Hirono Chemical) 100 overlapping parts Polyisocyanate (Eurack PU-614 [NCO content: 12.5%]: manufactured by Hirono Chemical) 33 superimposed In addition, together with the above, 12 parts of toluene, 6 parts of ethyl acetate, 6 parts of butyl acetate, and 6 parts of ethyl cellosolve acetate were added and mixed. NCO / OH of this solution
The molar ratio is 1.1 / 1.0.

Next, the roll surface was treated as follows. After immersing the elastic roller manufactured by the above method in the solution for 50 seconds, the surface layer 103 is cured at 100 ° C. for 8 hours. The film thickness of the surface layer 103 was 2.3 to 4.0 μm, and the volume resistance after forming the surface layer was 8 × 10 ⁷ Ω · cm.
To measure the film thickness of the surface layer 103, the cross section near the roller surface is
It was observed with a scanning electron microscope (JSM-35C: manufactured by JEOL Ltd.).

The charging roller manufactured as described above is mounted in place of the primary corona charger of the regular developing type copying machine FT5500 (manufactured by Ricoh), and is brought into contact with the surface of the photoconductor (OPC) drum to be driven to rotate. I chose

As the primary charging voltage, a DC voltage of 1.4 KV
Is applied and continuously operated in an environment of 40 ± 45% at 20 ± 1 ° C., the potential measurement of the dark potential of the photoconductor at the initial stage, 5000 sheets and 10000 sheets, the contamination state of the charging roller surface, and the image. The quality etc. were measured and examined. Table 1 shows the results.

In Table 1, the state of contamination of toner on the surface of the charging roller was evaluated according to the following criteria. ◎ There is a slight amount of toner adhered, but you can easily wipe off the adhered matter on the roller surface with a cloth. ○ A little toner etc. remains on the roller surface after wiping. △ It cannot be wiped off completely and a thin film of toner etc. remains on the roller surface. × Toner or the like is strongly adhered to the roller surface.

[0059]

[Table 1]

[Examples 2, 3, Comparative Examples 1 and 2] In Examples 2, 3 and Comparative Examples 1 and 2, the addition amount of polyisocyanate (Eurac PU-614) was changed as shown in Table 1. Then, the same procedure as in Example 1 was performed except that the NCO / OH molar ratio was changed.

The film thickness of the surface layer 103 and the volume resistance value after the surface layer formation are shown in Table 1, and the same examination as in Example 1 was conducted. The results are shown in Table 1.

As described above, in the polyester polyol / polyisocyanate system, when the NCO / OH molar ratio is in the range of 1.1 / 1.0 to 1.8 / 1.0, the non-adhesiveness to the toner, The charging property maintains the initial state and there is no problem in durability.

However, the NCO / OH molar ratio is 0.9 /
If it becomes 1.0, toner adhesion is likely to occur and N
When CO / OH = 2.0 / 1.0, there is no problem in non-adhesiveness, but flexibility decreases and cracks occur,
An abnormal image (horizontal streaks) was generated due to the toner entering the cracks.

[Embodiment 4] In Embodiment 4, the charging member is prepared by the following method. First, the surface treatment solution was adjusted as follows.

Fluorine polyol (Lumiflon LF-601C main agent [OH value: 25 mgKOH / g]: Asahi Glass) 100 overlapping parts Polyisocyanate (Lumiflon LF-601C curing agent [NCO content: 9.5%]: Asahi Glass) 20 Overlapped part In addition to the above, toluene 110 overlapped part, xylene 1
10 overlapping parts were added and mixed. NCO / OH of this solution
The molar ratio is 1.0 / 1.0.

Next, the roller surface was treated as follows. The elastic roller manufactured in Example 1 was immersed in the solution for 60 seconds, and then the surface layer was cured at 100 ° C. for 3 hours. The thickness of the surface layer was 3.0 to 3.8 μm, and the volume resistance after forming the surface layer was 9 × 10 ⁷ Ω · cm. This charging roller was examined in the same manner as in Example 1, and the results are shown in Table 2.
Shown in

[0067]

[Table 2]

[Examples 5, Comparative Examples 3 and 4] In Examples 5 and Comparative Examples 3 and 4, the addition amount of polyisocyanate (Lumiflon LF-601C curing agent) was changed as shown in Table 2. Then, the same procedure as in Example 4 was performed except that the NCO / OH molar ratio was changed. Table 2 shows the film thickness of the surface layer and the volume resistance after forming the surface layer. Further, the same examination as in Example 1 was conducted, and the results are shown in Table 2.

As can be seen from the above results,
In the polyisocyanate system, when the NCO / OH molar ratio is in the range of 1.0 / 1.0 to 1.7 / 1.0, the non-adhesiveness to toner and the like and the charging property maintain the initial state, and the durability is also improved. there is no problem.

However, the NCO / OH molar ratio is 0.9 /
If it becomes 1.0, toner adhesion tends to occur, and if it becomes 1.9 / 1.0, there is no problem with non-adhesiveness, but the flexibility of the surface layer decreases and cracks occur An abnormal image (horizontal streaks) was generated due to toner getting in.

[Sixth Embodiment] In the sixth embodiment, the charging member is manufactured by the following method. First, the surface treatment solution was adjusted as follows.

Polybutadieneol (POLY BD, R-45HT [OH value: 46.6 mgKOH / g]: manufactured by Idemitsu Oil Chemicals Co., Ltd.) 100 superposition portion Polyisocyanate (Coronate HL [NCO content: 12.8%]: Nippon Polyurethane 27.5 superposed part In addition to the above, 20 superposed parts of xylene were added and mixed. The NCO / OH molar ratio of this solution is 1.0 / 1.0.

Next, the roller surface was treated as follows. The elastic roller prepared in Example 1 was added to the above solution.
After soaking for 2 seconds, the surface layer was cured at 120 ° C. for 2 hours. The film thickness of the surface layer was 3.0 to 3.5 μm, and the volume resistance after forming the surface layer was 1 × 10 ⁸ Ω · cm. This charging roller was examined in the same manner as in Example 1, and the results are shown in Table 3.
Shown in

[0074]

[Table 3]

[Examples 7 and 8, Comparative Examples 5 and 6] In Examples 7 and 8 and Comparative Examples 5 and 6, the addition amount of polyisocyanate (Coronate HL) was changed as shown in Table 3, respectively. Same as Example 6 except that the NCO / OH molar ratio was changed. Table 3 shows the film thickness of the surface layer and the volume resistance after the surface layer was formed.

As shown in the above results, in the polybutadiene polyol / polyisocyanate system, when the NCO / OH molar ratio is in the range of 1.0 / 1.0 to 1.8 / 1.0, the non-adhesiveness to the toner and the charging The characteristics are almost in the initial state, and there is no problem in durability.

However, the NCO / OH molar ratio is 0.8 /
When it becomes 1.0, toner adhesion easily occurs and 1.9
At /1.0, the flexibility of the surface layer deteriorates, making it difficult to follow the elasticity of the elastic layer, and wrinkles are generated in the surface layer, causing lateral streaking.

[Embodiment 9] In Embodiment 9, a charging member is prepared by the following method. First, the surface layer treatment liquid was adjusted as follows.

Silicone-modified polyol (SF8428 [OH value: 400 mg KOH / g]: manufactured by Toray Dow Corning Silicone) 100 superposed parts Polyisocyanate (Millionate MR-100 [NCO content 30%]: manufactured by Nippon Polyurethane) 100 superposed parts In addition to the above, 400 parts of ethyl acetate were added and mixed. The NCO / OH molar ratio of this solution is 1.0 / 1.
0.

Next, the roller surface treatment was performed as follows.
The elastic roller manufactured in Example 1 was immersed in the solution for 60 seconds, and then the surface layer was cured at 120 ° C. for 4 hours.
The film thickness of the surface layer was 3.1 to 3.8 μm, and the volume resistance after forming the surface layer was 3 × 10 ⁸ Ω · cm. This charging roller was examined in the same manner as in Example 1, and the results are shown in Table 4.

[0081]

[Table 4]

[Example 10, Comparative Examples 7 and 8] Example 1
0 and Comparative Examples 7 and 8 were the same as Example 9 except that the addition amount of polyisocyanate (Millionate MR-100) was changed as shown in the display 4 and the NCO / OH molar ratio was changed. Table 4 shows the film thickness of the surface layer and the volume resistance after forming the surface layer. Further, the same examination as in Example 1 was conducted, and the results are shown in Table 4.

As described above, in the silicone-modified polyol / polyisocyanate system, when the NCO / OH molar ratio is in the range of 1.0 / 1.0 to 1.8 / 1.0, the non-adhesiveness to the toner, The charging property maintains the initial state and there is no problem in durability.

However, the NCO / OH molar ratio is 0.8 /
When it becomes 1.0, toner adhesion easily occurs and 1.9
When the ratio is /1.0, there is no problem in non-adhesiveness, but the flexibility of the surface layer is reduced, and horizontal streak-like cracks are likely to occur.

[Embodiment 11] In Embodiment 11, a charging member is prepared by the following method. First, as the conductive support 101, a φ8 mm stainless steel core is used. Next, the semiconductive elastic layer 102 is made of the following compound.

GECO-based epichlorohydrin rubber (Epichroma CG: manufactured by Daiso) 100 superposition portion azodicarbonamide (Celmic C: manufactured by Sankyo Kasei) 1.5 superposition portion tetramethylthiuram disulfide (Nocceller TT: manufactured by Ouchi Shinko Chemical Co., Ltd.) 1 superposition portion Part Sulfur (Salfax PMC: made by Tsurumi Chemical Co., Ltd.) 0.3 Superposed part Antimony trioxide (Atox S: made by Nippon Mining Co., Ltd.) 7 Superposed part Aluminum hydroxide (Hidilite H42S: Showa Denko) 25 Superposed part Chlorinated paraffin ( Empara K-65: made by Ajinomoto Co., Ltd. 15 superposed parts tin stearate (made by Kyodo Pharmaceutical) 2 superposed parts

After thoroughly kneading the above mixture with a two-roll mill, a stainless steel core having a diameter of 8 mm was subjected to a molding method (vulcanization: 150 ° C. × 45 minutes, secondary vulcanization: 155 ° C. × 20).
A semiconductive elastic layer 102 of a roller-shaped foam transfer charging member having an outer diameter of 20 mm.

The average bubble diameter of this elastic roller is 50 to 1
It was a single bubble of 00 μm, the roller resistance was 3 × 10 ⁶ Ω, and the roller rubber hardness was 30 degrees (JisC). The volume resistance of the solid rubber excluding the foaming agent (azodicarbonamide: Celmic C) from the above composition is 6 × 10 ⁷ Ω.
・ It was cm.

Next, a surface layer was formed on the semiconductive foamed elastic layer by the following method. The same surface layer treatment liquid as that used in Example 4 was used. The roller surface treatment was also performed in the same manner as in Example 4.

The transfer roller manufactured as described above is mounted in place of the transfer corona charger of the positive developing type copying machine FT5500 (manufactured by Ricoh), and the transfer charging voltage is DC-55.
0V applied, continuous operation, initial, 5000 sheets, 10
For 000 sheets, the state of contamination by the toner on the surface of the transfer roller and the image quality were measured and examined. The results are shown in Table 5.

[0091]

[Table 5]

[Example 12, Comparative Examples 9 and 10] Example 1
2, and Comparative Examples 9 and 10 were the same as Example 11 except that the addition amount of polyisocyanate (Lumiflon LF-601C curing agent) was changed as shown in Table 5 and the NCO / OH molar ratio was changed. ,investigated. The results are shown in Table 5.
Shown in

As described above, in the fluoropolyol / polyisocyanate system, the NCO / OH molar ratio was 1.
In the range of 0 / 1.0 to 1.7 / 1.0, the non-adhesiveness to toner and the like can be sufficiently maintained, and the durability is not a problem.

However, the NCO / OH molar ratio is 0.9 /
When it becomes 1.0, toner adhesion is likely to occur, and along with that, roller resistance also rises and transfer unevenness occurs. On the other hand, when the ratio is 1.9 / 1.0, the flexibility of the surface layer is lowered, the foam cells on the roller surface are partially broken, and uneven transfer occurs.

As is apparent from Examples 1 to 12 and Comparative Examples 1 to 10 as described above, by applying a DC voltage to the charging member of the present invention, the non-adhesiveness of the surface of the charging member is improved. It is possible to suppress toner adhesion on the surfaces of the charging roller and the transfer roller. That is, good output image quality can be maintained by obtaining stable charging characteristics for a long period of time.

Further, in order to improve the non-adhesiveness of the surface of the charging member, it is possible to maintain a good output image quality for a long period of time by ensuring an appropriate NCO / OH molar ratio.

[0097]

As described above, the charging member (Claim 1) of the present invention is a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support. Since a surface layer made of a resin mainly composed of a polymer of polyester polyol and polyisocyanate is provided on the conductive elastic layer, it is possible to prevent toner and the like from adhering to the surface of the semiconductive elastic layer, and to prevent charging. The durability of the member can be improved. Further, it is possible to maintain stable and good uniform charging characteristics and output image quality for a long period of time.

The charging member of the present invention (claim 2) is
In a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, a surface made of a resin mainly composed of a polymer of fluoropolyol and polyisocyanate is provided on the semiconductive elastic layer. Since the layer is provided, it is possible to prevent toner and the like from adhering to the surface of the semiconductive elastic layer and improve the durability of the charging member. Further, it is possible to maintain stable and good uniform charging characteristics and output image quality for a long period of time.

The charging member of the present invention (claim 3) is
In a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, a surface composed of a resin mainly composed of a polymer of polybutadiene polyol and polyisocyanate is provided on the semiconductive elastic layer. Since the layer is provided, it is possible to prevent toner and the like from adhering to the surface of the semiconductive elastic layer and improve the durability of the charging member. Further, it is possible to maintain stable and good uniform charging characteristics and output image quality for a long period of time.

The charging member of the present invention (claim 4) is
A charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein the semiconductive elastic layer comprises a resin mainly composed of a polymer of a silicone-modified polyol and polyisocyanate. Since the surface layer is provided, it is possible to prevent toner and the like from adhering to the surface of the semiconductive elastic layer, and improve the durability of the charging member. Further, it is possible to maintain stable and good uniform charging characteristics and output image quality for a long period of time.

The charging member of the present invention (claim 5) is
The NCO / OH molar ratio of the polyol of the resin forming the surface layer and the polyisocyanate is 1.0 / 1.0 to
Since it is 1.8 / 1.0, the non-adhesiveness of the surface of the charging member is improved. Also, by ensuring an appropriate NCO / OH molar ratio, it is possible to maintain good output image quality for a long period of time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration example of a charging member (roller shape) of the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a charging member (flat plate shape) of the present invention.

FIG. 3 is an explanatory diagram showing a configuration example of a charging member (belt-shaped) of the present invention.

FIG. 4 is an explanatory diagram showing a configuration example of an electrophotographic apparatus to which the charging member of the present invention is applied.

FIG. 5 is an explanatory diagram showing a configuration example of an electrophotographic apparatus to which the charging member of the present invention is applied.

[Explanation of symbols]

 Reference Signs List 101 conductive support 102 semiconductive elastic layer 103 surface layer 401 charging member 403 developing device 404 transfer charging device 405 cleaning device 407 electrophotographic photoreceptor 408 transferred member 501 charging corona charger 502 transfer charging member

Claims (5)

[Claims] 1. A charging member having a semiconductive elastic layer mainly composed of epichlorohydrin rubber formed on a conductive support, wherein a polymer of polyester polyol and polyisocyanate is mainly formed on the semiconductive elastic layer. A charging member, characterized in that a surface layer made of a resin is provided. 2. A charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein a polymer of fluoropolyol and polyisocyanate is mainly formed on the semiconductive elastic layer. A charging member, characterized in that a surface layer made of a resin is provided. 3. A charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein a polymer of polybutadiene polyol and polyisocyanate is mainly formed on the semiconductive elastic layer. A charging member, characterized in that a surface layer made of a resin is provided. 4. A charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, wherein a polymer of a silicone-modified polyol and polyisocyanate is mainly formed on the semiconductive elastic layer. A charging member, characterized in that a surface layer made of a resin is provided. 5. The NCO / OH molar ratio of the polyol of the resin forming the surface layer and the polyisocyanate is
The charging member according to claim 1, 2, 3 or 4, wherein the charging member has a ratio of 1.0 / 1.0 to 1.8 / 1.0.