JPH07104577A - Contact member for electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the generation of crack on a photosensitive body in repeated use and to form a stable image over a long term by specifying a contact member with the photosensive body. CONSTITUTION:A composition constituting the member to be in contact with the photosensitive body is made of a material which does not contain 50ppm or more isopropyl alcohol(IPA) or isobutyl alcohol(i-BuOH) as hydrolysis product or heat decomposition product. That is, the composition constituting the contact material produces IPA or i-BuOH by reacting a residual unreacted coupling agent with moisture in the air to be hydrolyzed or thermally decomposing when one part of the constituting material is treated with the coupling agent at the time of adjusting. Then, the content of IPA or i-BuOH is controlled so as not to be >=50ppm. As a result, the generation of crack on the photosensitive body is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus (including an electrostatic image forming apparatus) such as a developing roller, a charging roller, a transfer belt, a cleaning blade and a cleaning brush which come into contact with a photosensitive member. The present invention relates to a body contact member.

[0002]

2. Description of the Related Art Conventionally, in image forming apparatuses such as electrophotographic copying machines, printers, and facsimiles, a photoreceptor is charged, exposed and developed to form a toner image, which is transferred onto a transfer paper. The residual toner image is removed by cleaning and the charge is removed. Therefore, in the image forming apparatus, in order to remove the developing roller (toner carrying member) carrying a thin toner layer for developing the latent image on the photoconductor, the transfer belt for carrying the transfer paper, and the residual toner image. The cleaning blade, the cleaning brush, etc. come into contact with the photoconductor, and when the contact charging method is adopted, the charging roller naturally comes into contact with the photoconductor.

Further, as the photoconductor used in the electrophotographic system, a photoconductor having a photosensitive layer mainly containing selenium or a selenium alloy on a conductive support, an inorganic photoconductive material such as zinc oxide or cadmium sulfide. Are generally known, such as those in which a binder is dispersed in a binder, those using an organic photoconductive material such as poly-N-vinylcarbazole and trinitrofluorenone or an azo pigment, and those using an amorphous silicon-based material. There is. However, in recent years, as the speed and size of the electrophotographic image forming apparatus have increased, there has been a strong demand for reliability of the photoconductor capable of maintaining high image quality even when repeatedly used for a long time.

One of the main causes of impairing the life of the photoconductor in the image forming apparatus is the abrasion and scratches caused by mechanical stress applied from the developing process, cleaning process, copy paper and the like.
That is, in a photoreceptor (drum shape, belt shape), particularly in a belt shape photoreceptor (base is electroformed nickel, PET, etc.), repeated use causes cracks in the photosensitive layer, resulting in image defects. The positions of cracks occur in places where stress is likely to be applied at the bent portion and in the vicinity of the member that comes into contact with the photoconductor. In particular, cracks occur frequently at high temperatures and high humidity, which is a serious problem.

As for the contact member of the photosensitive member, a semiconductive polymer composition mixed with conductive material particles having a specific resistivity is used as a developing roller which is less likely to cause image unevenness, and a coupling agent is used. Suitable for surface-treated rolls (JP-A-1-102485) and direct contact electrophotography in which a thin-walled bonded magnet layer composed of a magnetoplumbite ferrite having a specific particle size and a polymer binder is laminated on a substrate. Derivative roll (Japanese Patent Laid-Open No. 4-3
No. 21075), but no consideration is given to the durability of the photoconductor during repeated use.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its purpose is to select a contact member for contacting with a photosensitive member so that the photosensitive member can be exposed to light repeatedly. Prevents the occurrence of body cracks,
An object of the present invention is to provide a contact member for an electrophotographic photosensitive member, which enables stable image formation for a long term.

[0007]

According to the present invention, in the electrophotographic image forming apparatus, the composition constituting the member in contact with the photoreceptor contains isopropyl alcohol or isobutyl alcohol as the hydrolysis or thermal decomposition product. 50p
There is provided a contact member for an electrophotographic photoreceptor, which is characterized by not containing pm or more.

According to the present invention, there is provided a contact member for an electrophotographic photosensitive member, wherein the contact member is dispersed or surface-treated with a coupling agent, and the coupling agent is a silane coupling agent. There is provided a contact member for an electrophotographic photoreceptor, which is at least one of an agent, a titanium-based coupling agent, and an aluminate-based coupling agent.

The present inventors have examined the constituent material of the contact member with the photoconductor in the electrophotographic image forming apparatus, and found that isopropyl alcohol (IPA) or isobutyl alcohol (i-BuO) in the composition constituting the material.
It was found that the content of H) correlates with the occurrence of cracks on the photoconductor. That is, in the composition constituting the contact material, a part of the constituent material may be subjected to a coupling agent treatment at the time of its preparation, but at this time, the unreacted coupling agent remaining in the material is IPA or i-BuOH by reacting with water in the air to hydrolyze or by thermal decomposition
To occur. In the contact member for electrophotographic photoreceptor of the present invention, the content of IPA and i-BtOH is 50 pp.
Since the content of m or more is not included (it is eliminated or reduced as much as possible), it is possible to prevent the occurrence of cracks in the photoconductor.

The case where the developing roller is taken up as the contact member with the photosensitive member will be mainly described. Electrophotography,
Particularly in the dry one-component developing method, the developing roller surface material needs to have a uniform resistivity, and if the uniformity varies, an image unevenness corresponding thereto is generated, and an image unevenness tends to occur when the dielectric constant is low. Therefore, as the surface material of the developing roller, it is preferable that the specific resistance shows semiconductivity and the high dielectric constant. This surface material is generally adjusted to obtain predetermined electric characteristics by adding conductive material particles to a polymer material such as rubber or resin. However, it is not possible to obtain a material having a semiconductive region and a high dielectric constant. It's quite difficult. Therefore, for example, it has been proposed to use particles surface-treated with a coupling agent as conductive material particles (JP-A-1-102485). Since the insulating thin film is formed on the surface of the surface-treated particles, the probability of mutual contact of the particles is reduced, and the decrease in specific resistance is suppressed.

Examples of the coupling agent used in this case include a silane coupling agent, a titanium coupling agent, and an aluminate coupling agent. Examples of the silane coupling agent include vinylsilane, epoxy-modified silane, and Examples thereof include amino-modified silane, carboxy-modified silane, mercapto-modified silane and the like. Typical examples of these silane coupling agents are vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-Epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N -Β (aminoethyl) γ
-Aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-chloropropyltrimethoxysilane.

As the titanium-based coupling agent,
Examples include alkoxy type, chelate type, and coordinate type. Typical examples of these are isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl birophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate. Phyto) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (di-tridecyl) phosphite titanate, bis (dioctylbairophosphate) oxyacetate titanate, bis (dioctylbylophosphate) ethylene titanate, etc. Can be mentioned. Examples of the aluminate coupling agent include acetoalkoxyaluminum diisopropylate.

Among the above coupling agents, it is preferable to use a silane coupling agent having a relatively high specific resistance. In this case, the type of the silane coupling agent is appropriately selected in consideration of the affinity with the insulating polymer used. For example, as the insulating polymer, it is appropriate to use an amino-based one when a phenol resin is used and an epoxy-based silane coupling agent when an epoxy resin is used. The surface treatment of the conductive material particles using such a coupling agent is carried out by dissolving the above coupling agent in water or an organic solvent such as n-hexane, benzene or toluene and immersing the conductive material particles in this solution. , Or after spraying the solution onto the conductive material particles,
It is performed by drying.

The surface material of the developing roller can be obtained in the form of powder or resin sheet by kneading the insulating polymer material and the conductive material particles surface-treated with the coupling agent. Then, the resin sheet is appropriately cut and pelletized, or powdered and used.

When the conductive material particles surface-treated with the coupling agent as described above are used, the composition constituting the surface material of the developing roller contains the residual unreacted coupling agent. The unreacted coupling agent reacts with water in the air to hydrolyze or by thermal decomposition to give IP
Generates A and / or i-BuOH. As described above, in the contact member for an electrophotographic photosensitive member of the present invention (in this case, the developing roller surface material), this IPA or i-B is used.
It is characterized in that it does not contain 50 ppm or more of uOH. That is, when the content of IPA or i-BuOH is less than 50 ppm, the occurrence of cracks on the photoconductor is prevented. From this, it is presumed that IPA and i-BuOH act on the photoconductor to cause cracks in portions where stress is easily applied due to pressure contact, bending, and the like. IPA and i-BuOH
As a means for reducing the content of the above, the unreacted coupling agent may be previously removed from the composition for contact members, or the composition may be isolated with a resin film or the like.

Although the case where the developing roller is used as the contact member with the photosensitive member has been described above, the member is a charging roller in the contact charging system, a transfer belt for transferring the transfer paper, or cleaning for removing the residual toner image. Needless to say, the same applies to blades, cleaning brushes, and the like.

[0017]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited thereby. All parts shown below are based on weight.

(Production of Photoreceptor) 117.7 Parts Anatase Titanium Oxide (TP-2; Purity 99.9%, Fuji Titanium Co., Ltd.) Alkyd Resin 22.9 parts (M-6404-50, Dainippon Ink and Chemicals, Inc.) Melamine resin 12.7 parts (Super Beckamine, L-117-60, manufactured by Dainippon Ink and Chemicals) Methyl ethyl ketone (manufactured by Kanto Chemical Co., Inc.) Using an alumina ball, ball milling was performed for 48 hours to prepare an undercoat layer coating solution. An electrodeposited nickel belt (80 mmφ × 340 mm length, thickness 30 μm: manufactured by Ricoh), an aluminum vapor deposition mylar film (80 mmφ × 340 mm length, thickness 75 μm) and an aluminum drum (80 mmφ × 340 mm length × 1.0 mm)
(Thickness), coating and drying were performed to form an undercoat layer having a thickness of 10 μm.

On the other hand, the following composition Trisaz pigment represented by the following formula (Formula 1) (manufactured by Ricoh) 12.5 parts Butyral resin (XYHL, manufactured by UCC) 2.1 parts Cyclohexanone (manufactured by Kanto Kagaku) 182.5 The mixture consisting of parts is placed in a ball mill pot and 10 mmφ
After ball milling for 48 hours using a SUS ball, 300 parts of cyclohexanone was further added and milled for 1 hour. After milling, the mill base was taken out, cyclohexanone was added and diluted so that the solid content concentration was 1.8% by weight, and the mixture was stirred to prepare a coating solution for forming a charge generation layer.

[Chemical 1] This coating solution is applied to the undercoat layer and dried to give a thickness of about 0.2 μm.
m charge generating layer was created.

Subsequently, the following composition represented by the following formula (2): Charge-transporting substance (manufactured by Ricoh) 90 parts Polycarbonate resin (C-1400, manufactured by Teijin Chemicals) 100 parts Silicone oil (KF-50, Shin-Etsu Chemical Co., Ltd.) 0.002 parts Dichloromethane (manufactured by Kanto Chemical Co., Inc.) 866 parts of the charge transport layer coating solution is prepared, and the charge transport layer is coated and dried to form a charge transport layer having a thickness of 25 μm. It was created.

[Chemical 2]

Example 1 Chlorinated polyethylene having a chlorine content of 30% by weight 90 parts Ethylene / vinyl acetate copolymer 20 parts Polypropylene 10 parts 40% by volume of a resin mixture and Ba having a maximum grain boundary diameter of about 0.5 μm Ferrite was wet finely pulverized in water to have an average particle size of 1.2 μm, and 60% by volume of isotropic barium ferrite powder obtained by passing through a 32 mesh sieve was mixed with a high-speed rotary blade mixer. Then, the mixture was kneaded at 120 ° C. with a hot roll mill and cut to obtain a thermoplastic resin magnet kneaded product for molding. This is 18m in diameter
1.2m on the shaft surface with an extruder in which a crosshead die is mounted on a stainless steel shaft having a length of m and a length of 240 mm.
The coating molding was performed at 140 ° C. so that the thickness became m. The molded product was precisely cut on a lathe to a diameter of 20 mm, and the thickness of the resin magnet layer as the magnetic dielectric layer was set to 1 mm.
100 rollers were produced.

The conductive roller thus obtained was incorporated into an electrophotographic copying machine of the one-component developing system of a non-magnetic toner, development was carried out, and image evaluation and observation of the surface state of the photoreceptor were carried out.
The results are shown in Table 1. The rate of occurrence of cracks on the surface of the photoconductor was determined by contacting the photoconductor with a conductive roller (sample) (n
= 10 sets), 10 ° C 30% RH, 25 ° C 60% R
After standing at 30 ° C. and 90% RH for 1 week, the presence or absence of cracks was observed visually and by a microscope (50 times).
The incidence was calculated by the following formula. Crack occurrence rate = (number of cracked samples / total number of test samples) x 100 (%)

Comparative Example 1 In Example 1, isotropic barium ferrite powder was added to a titanium-based coupling agent [isopropyl triisostearoyl titanate: KR-TTS, manufactured by Ajinomoto Co., ... Reddish brown liquid, specific gravity (23 ° C.). 0.94] was added, and then a conductive roller was prepared, evaluated and observed in the same manner as in Example 1 except that the resin mixture was kneaded, and the IPA content of the roller was measured. The results are shown in Table 1. The IPA content of the roller is obtained by cutting out the roller, hydrolyzing it, and quantifying the extract by gas chromatography.

Comparative Example 2 In Comparative Example 1, after the isotropic ferrite powder was previously treated with the titanium-based coupling agent (KR-TTS),
A conductive roller was prepared in the same manner as in Comparative Example 1 except that it was kneaded with the resin mixture, and evaluation, observation and IPA content measurement were performed. The results are shown in Table 1.

Example 2 The procedure of Comparative Example 2 was repeated, except that the isotropic ferrite powder treated with the titanium-based coupling agent was further hydrolyzed, purified, and then kneaded with the resin mixture. A conductive roller was produced by the above, and evaluation, observation, and IPA content measurement were performed. The results are shown in Table 1.

[0026]

[Table 1]

Comparative Examples 3 to 4 and Example 3 A conductive roller was manufactured and evaluated in the same manner as Comparative Examples 1 and 2 except that the i-BuOH content was measured instead of the IPA content. When observed, the same results as in Comparative Examples 1 and 2 and Example 2 were obtained.

Examples 4 to 6 and Comparative Examples 5 to 6 With respect to the phenol resin having the compounding composition as shown in Table 2 below, FEF carbon as shown in the same table and FEF carbon treated with 5% silane coupling agent ( Silane coupling agent, KBE-903, manufactured by Shin-Etsu Silicon Co., Ltd.) 5% titanium-based coupling agent-treated FEF (titanium-based coupling agent, TTS, manufactured by Ajinomoto Co., Inc.) was added in an amount shown in the table. The mixture was kneaded to form a sheet having a thickness of 1 mm. Using the obtained semiconductive polymer composition, a conductive resin layer having a thickness of 1 mm was formed on the outer circumference of a stainless steel shaft having a diameter of 20 mm.

The conductive roller obtained as described above was incorporated into an electrophotographic copying machine of a one-component developing system of non-magnetic toner, and development was carried out to evaluate an image and observe the surface of the photoreceptor. The results are shown in Table 2. In addition, the relationship between the IPA amount or i-BuOH amount and the crack occurrence rate in all of the above Examples and Comparative Examples is illustrated in FIG.

[0030]

[Table 2]

From the above results, the following becomes clear. The photoconductor does not crack if the developing roller surface material has an IPA or i-BuOH content of less than 50 ppm. In Examples 1 and 4 in which the developing roller surface material containing a conductive material that has not been subjected to the coupling agent treatment is used, cracks do not occur in the photoconductor, but the image density is slightly low in terms of image quality, and image unevenness and the like occur. Occurrence was observed. Examples 2, 3, 5 and 6 using a developing roller surface material containing a conductive material having a reduced content of IPA or i-BuOH, which has been subjected to a purification treatment after the coupling agent treatment,
The image quality is also good. It is presumed that this is because the conductive material became well dispersed in the resin matrix by the coupling material treatment.

[0032]

According to the contact member for an electrophotographic photosensitive member of claim 1, the composition constituting the member contacting the photosensitive member does not contain isopropyl alcohol or isobutyl alcohol in an amount of 50 ppm or more as a hydrolysis or thermal decomposition product. Therefore, the contact member prevents the photoconductor from cracking.

Since the contact member for an electrophotographic photoreceptor according to claims 2 and 3 has been subjected to dispersion treatment or surface treatment with a coupling agent, this contact member can provide a high-density and high-quality image. The effect is added.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the content of IPA or i-BuOH in the surface material of a contact member and the crack occurrence rate of a photoconductor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 15/16 21/10 6605-2H G03G 21/00 318 (72) Inventor Shinichiro Yamaguchi Ota, Tokyo 1-3-6 Nakamagome, Ward Ricoh Co., Ltd.

Claims (3)

[Claims] 1. An electrophotographic image forming apparatus, wherein the composition of the member that contacts the photoconductor is one that does not contain 50 ppm or more of isopropyl alcohol or isobutyl alcohol as a hydrolysis or thermal decomposition product. And a contact member for an electrophotographic photoreceptor. 2. The contact member for an electrophotographic photosensitive member according to claim 1, wherein the contact member is subjected to a dispersion treatment or a surface treatment with a coupling agent. 3. The contact member for an electrophotographic photosensitive member according to claim 2, wherein the coupling agent is at least one of a silane coupling agent, a titanium coupling agent, and an aluminate coupling agent.