JPH0310266A - Electrifying member for electrophotography - Google Patents

Abstract

PURPOSE:To prevent the image blur and potential fluctuation arising from the deterioration of the electrostatic charge of a photosensitive body by adding a specific antioxidant to the electrifying member. CONSTITUTION:This electrifying member is incorporated therein with the addi tive expressed by formula I to absorb oznone NOx, etc., and to prevent the deterioration of the electrostatic charge. The cmpd. to be incorporated into this electrifying member is the antioxidant having three pieces of hindered phenol groups. In the formula, X2 denotes hydrogen or an alkenyl group having 2 to 10C or alkyl group having 1 to 10c. The amt. of the addition is preferably in a 0.1 to 50wt% range by the weight of the layer to be added to the electrify ing member. This range can be adequately determined by the resin to be added and the cmopatibility thereof and the function thereof to prevent the deteriora tion. There is generally no effect of preventing the deterioration if the amt. of the addition is <0.1wt.%. Troubles, such as degradation in film formability and moldaiblity, of the electrifying member are generated if the amt. exceeds 50we.%. The image blur by the deterioration of the electrostatic charge, the deterioration of the photosensitive body, etc., are lessened in this way and the always stable images having high quality are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic charging member for charging an electrophotographic photoreceptor, such as secondary charging, transfer charging, and neutralizing charging.

[Conventional technology]

The charging process in the electrophotographic process using an electrophotographic photoreceptor has conventionally applied a high voltage (DC) to a metal wire.
5 to 8 KV) is applied, and charging is performed by the generated corona. However, with this method, when corona occurs, corona products such as ozone and NOx alter the surface of the photoreceptor, causing image blurring and deterioration, and dirt on the wires affects image quality, resulting in white spots and black lines in the image. There were other problems.

On the other hand, in terms of power, the current flowing to the photoreceptor is 5 to 30
%, and most of it flowed to the shield plate, making it inefficient as a charging means.

In order to compensate for these drawbacks, many direct charging methods have been researched and proposed (Japanese Unexamined Patent Publications No. 178267-1982, No. 104351-1983, No. 584
, No. 0566, JP-A-58-139156,
(Japanese Unexamined Patent Publication No. 150975/1983). However, in reality, even if the photoreceptor is charged by the contact charging method as described above, the surface of the photoreceptor is not uniformly charged at each part, and uneven charging occurs. For example, in the reversal development method, even if a process below photoimage exposure is applied to a photoconductor with spotty charging unevenness, the output image will be a spotty black dot image corresponding to the spotty charging unevenness, and a high-quality image will not be obtained. Not yet.

Also in the contact charging method, discharge occurs during charging, and ozone, NOx, etc. are generated, although the amount is 1/10 to 1/1.00 less than in corona charging. Ozone, NOx, etc. alter the quality of the photoreceptor, causing image blurring and deterioration. In addition, ozone NOx and the like are adsorbed to the charging member and pressed against the photoreceptor, causing further deterioration.

[Problem that the invention seeks to solve]

It is an object of the present invention to solve the above-mentioned drawbacks and to prevent image blurring and potential fluctuations caused by charging deterioration of a photoreceptor.

[Means for Solving the Problems] As a result of investigation, the present inventors have discovered that the above object can be achieved by adding a specific antioxidant to the charging member.

That is, the present invention provides an electrophotography characterized by containing a compound represented by the following general formula (1) It is a charging member for

During the charging process, ozone, NOx, and active gases generated are adsorbed to the surface of the photoreceptor, and the adsorbed substances may disturb the charge of the electrostatic latent image (image blur) or deteriorate the material of the photosensitive layer (deterioration of sensitivity). ). The present invention attempts to prevent charging deterioration by absorbing ozone, NOx, etc., using a specific additive in the charging member.

The compound contained in the charging member is an antioxidant having three hindered phenol groups.

This additive is dissolved or dispersed or kneaded and incorporated into the conductive polymer material, insulating resin, etc. of the charging member. Further, when the charging member has a multilayer structure, it is preferably contained in the outermost layer thereof.

The amount added is 0.0% based on the weight of the layer to which the charging member is added.
The range is preferably from 1% to 50 wt%, and can be determined as appropriate depending on the resin to be added, its compatibility and deterioration prevention effect.

In general, if the amount added is less than 0.1 wt%, there is no effect of preventing deterioration, and if it exceeds 50 wt%, problems such as a decrease in film forming properties and moldability of the charging member will occur. It can also be used in combination with other additives, such as other antioxidants and lubricants.

Materials for the charging member include metals such as aluminum, iron, and copper, conductive polymer materials such as polyacetylene, polypyrrole, and polythiophene, rubbers such as imprene rubber and quawaprene rubber that have been treated to be conductive by dispersing carbon, polycarbonate, and polyethylene. , polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, and other resins can be used. The volume resistance of the surface of the charging member is 1 from the viewpoint of good charging and prevention of dielectric breakdown.
00~1012Ω"cm, especially 102~1010Ω"
A range of cm is preferred. In addition, in order to reduce voltage drop caused by excessive current flowing when the photoreceptor has a defect such as dielectric breakdown, the surface layer of the charging member is made of a material having a volume resistance of 106 to 10, such as alkoxymethylated nylon.
It is also possible to use resin scraps of about 12 Ω·cm to form a multilayer structure.

The charging member for electrophotography of the present invention may have a structure in which, for example, a single layer containing the above-mentioned additive or a multilayer having a surface layer containing the above-mentioned additive is provided on a conductive substrate.

Further, examples of the shape of the charging member include a roller shape and a blade shape.

Examples of the conductive substrate include iron, copper, and stainless steel.

An electrophotographic photoreceptor basically has a structure in which a photosensitive layer is provided on a conductive support. As the conductive support, materials that are conductive themselves such as aluminum, aluminum alloy, stainless steel, chromium, titanium, etc. can be used. In addition, aluminum, aluminum alloy, indium oxide-tin oxide alloy, etc. can be used. The conductive support or plastic has a layer formed by vacuum deposition, a support in which plastic or paper is impregnated with conductive particles (e.g. carbon black, tin oxide particles, etc.) together with a suitable binder, or a conductive binder. Plastic or the like can be used.

A subbing layer having barrier and adhesive functions may be provided between the conductive support and the photosensitive layer. The subbing layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane,
It can be formed from gelatin, aluminum oxide, etc.

The thickness of the subbing layer is 5 μm or less, preferably 0.5 to 3 μm.
m is appropriate.

In order for the subbing layer to perform its function, it must have a resistance of 107Ω・cm.
The above is desirable.

The photosensitive layer is formed, for example, by coating a photoconductor such as an organic photoconductor, amorphous silicon, selenium, etc. together with a binder if necessary, or by vacuum deposition. Furthermore, when using an organic photoconductor, a photosensitive layer consisting of a combination of a charge generation layer that generates charge carriers upon exposure to light and a charge transport layer that has the ability to transport the generated charge carriers can also be effectively used.

The charge-generating layer may be formed by depositing one or more charge-generating materials such as azo pigments, quinone pigments, quinocyanine pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, and quinacridine pigments, or by depositing a suitable material. It can be formed by dispersing coating with a binder (or without a binder).

The binder can be selected from a wide range of insulating resins or organic photoconductive polymers. For example, insulating resins include polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, acrylic resin, polyacrylamide resin, polyamide, cellulose resin, urethane resin, epoxy resin, Examples include casein and polyvinyl alcohol. Further, examples of the organic photoconductive polymer include carbazole, polyvinylanthracene, polyvinylpyrene, and the like.

The thickness of the charge generation layer is 0.01-15 μm, preferably 0.
．． 05 to 5 μm, and the weight ratio of the charge generation layer to the binder is 10:1 to 1:20.

The solvent used in the paint for the charge generation layer is selected based on the solubility and dispersion stability of the resin and charge transport material used. Examples of organic solvents include alcohols, sulfoxides, ethers, Nisels, and aliphatic solvents. Genified hydrocarbons or aromatic compounds can be used.

Coating can be performed using a coating method such as a dip coating method, a spray coating method, a Meyer bar coating method, or a blade coating method.

The charge transport layer is formed by dissolving a charge transport material in a film-forming resin. Examples of organic charge transport materials used in the present invention include hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds,
Examples include thiazole compounds and triarylmethane compounds. These charge transport materials can be used alone or in combination of two or more.

Examples of binders used in the charge transport layer include phenoxy resin, polyacrylamide, polyvinyl butyral, polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenolic resin, and epoxy. Resin, polyester, alkyd resin, polycarbonate, polyurethane or two of the repeating units of these resins
Copolymers containing at least one of styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, and the like can be mentioned. It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

The thickness of the charge transport layer is 5 to 50 μm, preferably 8 to 20 μm.
μm, and the weight ratio of charge transport material and binder is 5:1
~1:5, preferably about 3.1 ~ 1:3. The coating method described above can be used for coating.

Furthermore, dyes, pigments, organic charge transport substances, and the like are generally susceptible to ultraviolet rays, ozone, stains caused by oil, and metals, so a protective layer may be provided as necessary. In order to form an electrostatic latent image on this protective layer, the surface resistivity is 1011.
It is desirable that it is Ω or more.

Protective layers that can be used in the present invention include polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butylene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. It is formed by dissolving a resin in a suitable organic solvent and applying it to the second part of the photosensitive layer and drying it.

At this time, the thickness of the protective layer is generally in the range of 0.05 to 20 μm. This protective layer may contain an ultraviolet absorber or the like.

The charging member of the present invention can be applied to, for example, an electrophotographic apparatus as shown in FIG. This device includes a roller-shaped charging member 2, image exposure means 3, developing means 4, transfer charging means 6, separation charging means 7,
A cleaning means 8 and a pre-exposure means 10 are arranged.

A charging member 2 placed in contact with the electrophotographic photoreceptor 1 is supplied with a voltage (for example, 200 V or more, 2,000
Applying a pulsating voltage (which is a superimposition of a DC voltage of V or less and an AC voltage of a peak-to-peak voltage of 4000 V or less) to the electrophotographic photoreceptor]
The surface is charged, and the image on the original is image-exposed onto the photoreceptor by the image exposure means 3 to form an electrostatic latent image. Next, the developing means 4
The electrostatic latent image on the photoreceptor is developed (visualized) by adhering the developer therein to the photoreceptor, and the developer on the photoreceptor is transferred to the paper feed roller and the feeder by the transfer charging means 6. The developer is transferred to a transfer member such as paper that has passed through the paper kite 5, and the developer remaining on the photoreceptor without being transferred during the transfer is collected by the cleaning means 8. On the other hand, the transferred member is separated by the separating and charging means 7, and transferred to the fixing device (
(not shown).

An image can be formed by such an electrophotographic process, but if residual charges remain on the photoreceptor, the photoreceptor is exposed to light by the pre-exposure means 10 to remove the residual charges before performing primary charging. It is better to eliminate static electricity.

By applying the charging member of the present invention to an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor, which easily deteriorates in terms of mechanical strength and chemical stability, its characteristics can be significantly exhibited. be able to.

The method of installing the charging member in contact with the photoreceptor in the present invention is not limited to a specific method, and the charging member may be fixed or moved by rotating in the same direction or opposite direction to the photoreceptor. Ru.

Furthermore, it is also possible to cause the charging member to function as a developer cleaning device on the photoreceptor.

Regarding the voltage applied to the charging member in the direct charging of the present invention and the application method, it depends on the specifications of each electrophotographic device, but in addition to the method of instantly applying the desired voltage, there are also methods to apply the voltage in stages for the purpose of protecting the photoreceptor. In the case of applying a superimposed alternating current on direct current, a method can be adopted in which the voltage is applied in the order of direct current and alternating current or alternating current and direct current.

Note that when direct current is applied in the form of superimposed alternating current, the current increases and more products such as ozone and NQx are generated than when direct current is applied, which tends to cause deterioration of the photoreceptor, so the present invention is even more effective. It is.

Further, in the present invention, processes such as image exposure, development, and cleaning can be performed using any method known in the field of electrostatic photography, and are not limited to a specific type of developer. The charging member of the present invention can be used not only in copying machines but also in electrophotographic applications such as racer printers, CRT printers, and electrophotographic plate making systems.

Example 1 100 parts by weight of chloroprene rubber and 5 parts by weight of conductive carphone were melt-kneaded and molded through a stainless steel shaft of 8 mm x 360 mm in the center to provide a base layer for a charging member. The volume resistivity of this base layer was measured in an environment with a temperature of 22° C. and a humidity of 60% and was found to be 3×10′Ω·cm.

Next, 610 parts by weight of ethoxymethylated nylon and 90 parts by weight of methanol were added to tris-(3,5-di-butyl-4).
-Hydroxybenzyl)-isocyanurate (HBCY
-1) was added to 0.02 parts, 0.3 parts, 1 part, and 5 parts, respectively, and dip-coated on the charging member base layer, and after drying, the film thickness was 20.
A 0 μm surface layer was formed and a roller-shaped charging member measuring φ20×340 mm was manufactured. Each charging roller is 1.
2. 3. Set it to 4.

Further, as comparative samples, charging rollers 56 without HBCY-1 and in which the amount added was 15 parts were manufactured. Using this charging roller, a Canon copier NP-3525 modified to the configuration shown in Figure 1 was used to produce 5000 copies.
The printing durability of the sheet was carried out in an environment of 35° C.990%, and image blurring, decrease in sensitivity of the photoreceptor, etc. were evaluated. The results are shown in Table 1.

Table 1 5 (Comparative sample) 6 (Comparative sample) 35 Not observed 0 0 100 Occurred after about 4000 sheets. It is the ratio to the total weight of the layer. Note that the surface layer of the charging roller 6 had poor film-forming properties, and a charging roller worthy of evaluation could not be manufactured.

Regarding deterioration in sensitivity after 5,000 sheets, the change in bright area potential (VL) of the photoreceptor (ΔVL) was measured. As is clear from Table 1, when a charging roller that does not contain additives is used, image blur and deterioration of the sensitivity of the photoreceptor are observed due to charging deterioration, but when a charging roller with an appropriate amount of additive is used. was able to reduce charging deterioration of the photoreceptor.

Example 2 Canon LBP-3X (laser beam printer)
The charging method was modified to the direct charging method according to the present invention. The charging member is made of 100 parts by weight of chloroprene rubber, 5 parts by weight of conductive carbon, and tris(3,5-cit-amyl-4-hydroxybenzyl)-isocyanury-(HB CY
-2), melt and knead 1 part, and center φ8 x 360 m.
φ20X through the stainless steel shaft of m 34. Om m
The charging roller 7 was formed by molding into a charging roller 7. Further, as a comparative sample, a charging roller 8 to which HBCY-2 was not added was manufactured. Using these charging rollers, printing durability was carried out on 4,000 sheets in the same environment as in Example 1 at 35° C. and 190%, and image blur, deterioration in sensitivity of the photoreceptor, etc. were evaluated. The results are shown in Table 2.

Table 2 5 Not observedAs is clear from Table 2, when a charging roller that does not contain additives is used, ozone NOx generated by charging
Blurredness and deterioration of sensitivity may be seen due to deposits such as
When a charging roller containing BCY-2 was used, there was little deterioration in sensitivity and little image blurring.

Example 3 100 parts by weight of chloroprene rubber and 10 parts by weight of conductive carphone were melt-kneaded and molded through a stainless steel shaft of 8 mm x 360 mm in the center to provide a base layer for a charging roller. Next, 10 parts by weight of methoxymethylated nylon and 9 parts by weight of methanol
The following additives shown in Table 3 were added to 0 parts by weight, and dip coating was applied onto the charging roller base layer to give a film thickness of 100 μm after drying.
A roller-shaped charging member having a diameter of 20 mm and a diameter of 340 mm was manufactured.

Table 3 The structure of the additives used (HB CY 1 to 6) is shown in Table 5.
Evaluation was performed in the same manner using P.

Table [Effects of the Invention] The electrophotographic charging member of the present invention has little image blurring, photoreceptor deterioration, etc. due to charging deterioration, and can always form stable, high-quality images.

4,

[Brief explanation of drawings]

FIG. 1 shows a schematic cross-sectional view of an electrophotographic apparatus.

Claims (1)

[Claims] (1) The following general formula (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) However, R: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ X_1: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. Element.