JP2001109277A - Intermediate transfer body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate transfer body which has excellent mechanical strength, is free from performance change by stress during use and may be industrially stably manufactured. SOLUTION: The intermediate transfer body having the functions to receive the transfer of toners, to transport the same to another place and to hold the toners before the transfer to a recording medium (A) has at least a polyimide layer consisting of polyimide as a main constituting material and (B) the polyimide layer contains polyaniline and a dopant capable of making the polyaniline conducting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic method, such as a copying machine or a printer, and more particularly to a method in which a toner image formed on an image carrier is temporarily transferred to an intermediate transfer member and then transferred to the intermediate transfer member. The present invention relates to an intermediate transfer member used in an image forming apparatus that transfers a reproduced image to a recording medium such as paper to obtain a reproduced image.

[0002]

2. Description of the Related Art An image forming apparatus using an electrophotographic method is:
A uniform charge is formed on an image carrier made of a photoconductive photoreceptor made of an inorganic or organic material, and an electrostatic latent image is formed with a laser beam or the like that modulates an image signal. The latent image is developed into a visualized toner image.
Then, the desired reproduced image is obtained by electrostatically transferring the toner image to a transfer material such as a recording paper via an intermediate transfer member or directly. Particularly, as an image forming apparatus adopting a system in which a toner image formed on the image carrier is primarily transferred to an intermediate transfer member, and a toner image on the intermediate transfer member is secondarily transferred to recording paper, Japanese Patent Laid-Open No. The one disclosed in 206567 is known.

As belt materials used in the image forming apparatus employing the above-mentioned intermediate transfer system, PC (polycarbonate resin, JP-A-06-095521), PVDF
(Polyvinylidene fluoride resin, Japanese Patent Application Laid-Open No. 05-20090)
4, JP-A-06-228335), polyalkylene phthalate resin (JP-A-06-149081), PC
/ PAT (polyalkylene terephthalate resin) blend material (JP-A-06-149083), ETFE
(Ethylene-tetrafluoroethylene copolymer) / P
It has been proposed to use a conductive endless belt of a thermoplastic resin such as a blend material of C, ETFE / PAT, and PC / PAT (Japanese Patent Application Laid-Open No. 06-149079).

The above-mentioned thermoplastic conductive materials such as polycarbonate resin and polyvinylidene fluoride resin have inferior mechanical properties (small Young's modulus). There is a problem that an image cannot be obtained stably and a belt life is short because a crack is generated from a belt end portion during driving. Examples of the material having excellent mechanical properties include a thermosetting polyimide material. JP-A-63-11263 proposes a carbon black-dispersed thermosetting polyimide seamless belt.

On the other hand, as the semiconductive material, besides the above-mentioned insulating resin to which a conductive filler is added, a blend of an insulating resin and a semiconductive resin is known. As a semiconductive polymer blend comprising an insulating resin and a conductive polyaniline, for example, a method of blending a powdered polyaniline by a mechanical method as disclosed in, for example, JP-A-64-69662 has been known. . As a method of mixing a polyaniline and an insulating resin in a solution state and solidifying a film to obtain a polymer blend, for example, a method of modifying polyaniline disclosed in Japanese Patent Application Laid-Open No. 2-500288 to make it soluble. And JP-A-4-63865.
The use of a solvent-soluble polyaniline disclosed in the above publication is already known.

However, these techniques have the disadvantage that the insulating resin and polyaniline uniformly mixed in the solution undergo phase separation during drying, and a uniform semiconductive film cannot be obtained. Therefore, when used as an intermediate transfer member for electrophotography, there are drawbacks in that mechanical properties are inferior and good electrophotographic images cannot be obtained because the electrical properties are not uniform. Furthermore, since the polyaniline is unevenly distributed, the resistance region suitable for an electrophotographic intermediate transfer member, for example, a resistance region of about 10 ⁷ Ωcm to about 10 ¹⁵ Ωcm, causes a slight variation in the production, that is, the addition of polyaniline. There is also a disadvantage that the resistance value fluctuates greatly due to variations in the amount, unevenness in the mixing step, and temperature unevenness during drying / solidification, and the control of the resistance value cannot be performed effectively.

On the other hand, as a method of using a polyimide having excellent mechanical properties and electrical properties as an insulating resin, for example, a method using a modified polyaniline is disclosed in JP-T2-500288. Although a smooth film can be obtained by this method, it is necessary to use an extremely expensive modified polyaniline as a raw material, and this is of low industrial value. Further, Japanese Patent Application Laid-Open No. 5-26291 discloses a method of compatibilizing polyaniline and a polyimide precursor by electrical interaction. A similar technique is disclosed in
No. 90179 and JP-A-8-259709. These methods produce semiconductive resin films with electrically uniform properties, but because both polymers are blends that are uniformly mixed, they have mechanical properties to be used as electrophotographic transfer materials. Is inferior. An example of adding a filler to a polymer blend comprising polyaniline and polyimide is disclosed in
No. 207012, a method of adding a metal oxide,
No. 176329 discloses a method of adding carbon black, but all of them aim at changing electrical characteristics, and have not solved the problem of mechanical strength at all.

[0008]

In the prior art described above, when an intermediate transfer member is formed by a conductive endless belt, the following problems occur. That is, when a seamless belt obtained by dispersing carbon black in a polyimide material having excellent mechanical properties is used as an intermediate transfer member, (1) the current applied at the time of transfer concentrates on carbon black, which is a low-resistance portion. (2) Since carbon black forms a structure and expresses conductivity, it causes electrical and mechanical stress during use. (3) Since the surface of the intermediate transfer member has a structure in which a high-resistance polyimide resin and low-resistance carbon black are randomly exposed, the discharge is exposed to carbon black. This occurs preferentially for the copy, and adversely affects the image quality. And other problems.

In addition, since the resistance is controlled by the contact between the carbon black particles or a site very close to each other, the resistance is inherently unstable, and greatly varies depending on, for example, the lot of carbon black, the mixing apparatus, and the film forming conditions. There is a problem that it is extremely difficult to obtain an intermediate transfer member having a uniform resistance industrially.

On the other hand, when a material obtained by blending a conductive resin such as polyaniline with polyimide is used as an intermediate transfer member, if the molecular weight and the amount of polyaniline are not sufficiently controlled, the resulting film cannot be obtained. Has poor mechanical properties, and does not function effectively as an electrophotographic intermediate transfer member that requires high-precision mechanical driving.

An object of the present invention is to provide an intermediate transfer member which solves the above-mentioned drawbacks of the prior art, has excellent mechanical properties, has little change in performance due to stress during use, and can be manufactured stably industrially. is there. Another object of the present invention is to provide an intermediate transfer member having surface smoothness and surface flatness required as an intermediate transfer member.

[0012]

The intermediate transfer member of the present invention, which achieves the above object, has a function of receiving toner, transporting it to another place, and holding the toner until it is transferred to a recording medium. An intermediate transfer member having (A) at least a polyimide layer containing polyimide as a main constituent material, and (B) polyaniline,
And a dopant capable of making the polyaniline conductive. In the above-mentioned intermediate transfer member of the present invention, the polyaniline preferably has a number average molecular weight of 4,000 to 400,000. In the above-mentioned intermediate transfer member of the present invention, the amount of polyaniline added is preferably 3% to 30% by weight in the polyimide layer. The intermediate transfer member of the present invention has a volume resistivity of 10 ⁷ Ωcm to 10 ¹⁵ Ω.
cm. The intermediate transfer member of the present invention may have an elastic modulus of 200 kgf / cm.
It is preferably at least ² . The intermediate transfer member of the present invention is preferably such that a filler is added to the polyimide layer.The intermediate transfer member of the present invention has a particle diameter of the filler of 0.1 μm or more. The average particle diameter of the toner is preferably equal to or less than 1/2. Also,
In the above-mentioned intermediate transfer member of the present invention, it is preferable that a filling amount of the filler in the polyimide layer is 0.1 to 8% by volume fraction. Further, the intermediate transfer member of the present invention,
It is preferable that the coefficient of humidity expansion of the intermediate transfer member is 70 ppm / RH% or less.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

The intermediate transfer member of the present invention has a polyimide layer containing at least polyimide as a main constituent material, and the intermediate transfer member may be formed of a sheet or film composed of a polyimide layer. It may have at least a polyimide layer on a substrate.
The polyimide layer contains polyaniline and a dopant that can make the polyaniline conductive.

In the case of an intermediate transfer member composed of a sheet or film composed of a polyimide layer, it is actually produced by, for example, the following method. That is, 1) after forming a coating liquid in which a polyamic acid, polyaniline, a dopant and a solvent are mixed into a long film by extrusion molding on a peelable substrate using a T-die by a known method, A method of imidizing a polyimide film by a known method, cutting the polyimide film into an appropriate length, and joining the opposing sides to each other by a joining means to obtain an endless belt 2).
After applying the above coating liquid to the inside of a cylindrical mold by a known method, the film thickness is leveled by rotating the mold, and dried to obtain a cylindrical film, and then imidized by a known method. 3) a method of obtaining the endless belt-like polyimide film by applying the above-mentioned coating solution to the inside of the cylindrical mold, and then inserting a nest inside the mold to level the film thickness. In addition, the intermediate transfer member of the present embodiment is a method that can be used for manufacturing an endless belt-shaped molded product.
It may be manufactured by that method. In the case of a sheet or film-like intermediate transfer body comprising a polyimide layer as described above, the thickness is preferably 0.020 mm to 1.0 mm, more preferably 0.050 mm to 0.200 m
m.

On the other hand, there is also a method of applying the above-mentioned coating liquid on a substrate to obtain an intermediate transfer member of the present embodiment. For example, an intermediate transfer member is obtained by applying the above-mentioned coating solution onto the surface of a metal or resin molded product, preferably a drum-shaped or belt-shaped molded product, and drying and imidizing. In the case of an intermediate transfer member having a polyimide layer on the above-described substrate, the thickness of the polyimide layer is preferably from 0.020 mm to 1.0 mm, more preferably from 0.050 mm to 0.20 mm.
0 mm.

The above polyamic acid can be obtained as a solution by dissolving a substantially equimolar mixture of a tetracarboxylic dianhydride or a derivative thereof and a diamine in an organic polar solvent and reacting in a solution state. It is preferable to use an aromatic tetracarboxylic dianhydride as the tetracarboxylic dianhydride and an aromatic diamine as the diamine, but other than these can be selected as necessary.

Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ', 4,4'-
Benzophenone tetracarboxylic dianhydride, 3,3 ', 4,4'
-Biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-
Biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetraanhydride Examples thereof include carboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, and bis (3,4-dicarboxyphenyl) sulfone dianhydride. These may be used alone or in combination of two or more.

As the aromatic diamine, for example, 4,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, p-
Phenylenediamine, m-phenylenediamine, benzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylpropane, 2, 2-bis [4- (4-aminophenoxy) phenyl] propane and the like can be mentioned. These may be used alone or in combination of two or more.

The above-mentioned polyaniline is preferably represented by the general formula (I)

Embedded image

(Wherein m and n represent the molar fractions of the quinone diimine structural unit and the phenylenediamine structural unit in the repeating unit, respectively, 0 <m <1, 0 <n <1, m
+ N = 1. Polyaniline having a quinone diimine structural unit and a phenylenediamine structural unit represented by formula (1) as main repeating units is used.

As the above dopant, a protonic acid can usually be preferably used. Protonic acids preferred as dopants are those having an acid dissolution constant pKa value of 4.8 or less. As such a protonic acid,
For example, in addition to inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, hydrofluoric acid, and perchloric acid, organic acids having an acid dissolution constant pKa value of 4.8 or less can be given. .

The organic acid is, for example, an organic carboxylic acid or a phenol, and preferably has an acid dissociation constant pKa
The value is 4.8 or less. Such organic acids include aliphatic, aromatic, araliphatic, alicyclic and other mono- or polybasic acids. Such an organic acid may have a hydroxyl group, a halogen, a nitro group, a cyano group, an amino group, and the like. Accordingly, specific examples of such organic acids include, for example, acetic acid, n-butyric acid, pentadecafluorooctanoic acid, pentafluoroacetic acid, trifluoroacetic acid, trichloroacetic acid, dichloroacetic acid, monofluoroacetic acid, monobromoacetic acid, monochloroacetic acid, cyanoacetic acid. , Acetylacetic acid, nitroacetic acid,
Triphenyl acetic acid, formic acid, oxalic acid, benzoic acid, m-bromobenzoic acid, p-chlorobenzoic acid, m-chlorobenzoic acid, p-chlorobenzoic acid, o-nitrobenzoic acid, 2,4-
Dinitrobenzoic acid, 3,5-dinitrobenzoic acid, picric acid, o-chlorobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, trimethylbenzoic acid, p-cyanobenzoic acid, m-cyanobenzoic acid, thymol Blue, salicylic acid, 5-aminosalicylic acid, o-methoxybenzoic acid, 1,6
-Dinitro-4-chlorophenol, 2,6-dinitrophenol, 2,4-dinitrophenol, p-oxybenzoic acid, bromophenol blue, mandelic acid, phthalic acid,
Isophthalic acid, maleic acid, fumaric acid, malonic acid, tartaric acid, citric acid, lactic acid, succinic acid, α-alanine, β-alanine, glycine, glycolic acid, thioglycolic acid,
Ethylenediamine-N, N'-diacetic acid, ethylenediamine-
N, N, N ', N'-tetraacetic acid and the like can be mentioned.

The organic acid may have a sulfonic or sulfuric acid group. Such organic acids include, for example, aminonaphtholsulfonic acid, metanylic acid, sulfanilic acid, allylsulfonic acid, lauryl sulfate, xylenesulfonic acid, chlorobenzenesulfonic acid,
Methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 1-butanesulfonic acid, 1-hexanesulfonic acid, 1-heptanesulfonic acid, 1-octanesulfonic acid, 1-nonanesulfonic acid, 1-decanesulfonic acid, 1
-Dodecanesulfonic acid, benzenesulfonic acid, styrenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, butylbenzenesulfonic acid, pentylbenzenesulfonic acid, hexylbenzenesulfonic acid, heptylbenzenesulfonic acid Acid, octylbenzenesulfonic acid,
Nonylbenzenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, diethylbenzenesulfonic acid, dipropylbenzenesulfonic acid, dibutylbenzenesulfonic acid, methylnaphthalene sulfone Acid, ethyl naphthalene sulfonic acid, propyl naphthalene sulfonic acid, butyl naphthalene sulfonic acid, pentyl naphthalene sulfonic acid, hexyl naphthalene sulfonic acid, heptyl naphthalene sulfonic acid, octyl naphthalene sulfonic acid, nonyl naphthalene sulfonic acid, decyl naphthalene sulfonic acid, undecyl naphthalene Sulfonic acid, dodecylnaphthalenesulfonic acid, pentadecylnaphthalenesulfonic acid,
Octadecyl naphthalene sulfonic acid, dimethyl naphthalene sulfonic acid, diethyl naphthalene sulfonic acid, dipropyl naphthalene sulfonic acid, dibutyl naphthalene sulfonic acid, dipentyl naphthalene sulfonic acid, dihexyl naphthalene sulfonic acid, diheptyl naphthalene sulfonic acid, dioctyl naphthalene sulfonic acid, dinonyl naphthalene Examples thereof include sulfonic acid, trimethylnaphthalenesulfonic acid, triethylnaphthalenesulfonic acid, tripropylnaphthalenesulfonic acid, tributylnaphthalenesulfonic acid, camphorsulfonic acid, and acrylamide-t-butylsulfonic acid.

In the present invention, a polyfunctional organic sulfonic acid having two or more sulfonic acid groups in the molecule can also be used. Such polyfunctional organic sulfonic acids include, for example, ethane disulfonic acid, propane disulfonic acid, butane disulfonic acid, pentane disulfonic acid, hexane disulfonic acid, heptane disulfonic acid, octane disulfonic acid, nonane disulfonic acid, decane disulfonic acid, benzene Disulfonic acid, naphthalenedisulfonic acid,
Toluene disulfonic acid, ethylbenzene disulfonic acid,
Propylbenzenedisulfonic acid, butylbenzenedisulfonic acid, dimethylbenzenedisulfonic acid, diethylbenzenedisulfonic acid, dipropylbenzenedisulfonic acid,
Dibutylbenzene disulfonic acid, methylnaphthalenedisulfonic acid, ethylnaphthalenedisulfonic acid, propylnaphthalenedisulfonic acid, butylnaphthalenedisulfonic acid, pentylnaphthalenedisulfonic acid, hexylnaphthalenedisulfonic acid, heptylnaphthalenedisulfonic acid,
Octylnaphthalenedisulfonic acid, nonylnaphthalenedisulfonic acid, dimethylnaphthalenedisulfonic acid, diethylnaphthalenedisulfonic acid, dipropylnaphthalenedisulfonic acid, dibutylnaphthalenedisulfonic acid, naphthalenetrisulfonic acid, naphthalenetetrasulfonic acid, anthracenedisulfonic acid, anthraquinonedisulfonic acid,
Phenanthylene disulfonic acid, fluorenone disulfonic acid, carbazole disulfonic acid, diphenylmethane disulfonic acid, biphenyl disulfonic acid, terphenyl disulfonic acid, terphenyl trisulfonic acid, naphthalenesulfonic acid-formalin condensate, phenanthrenesulfonic acid-formalin condensate, anthracene Sulfonic acid-formalin condensate, fluorene sulfonic acid-formalin condensate, carbazole sulfonic acid-formalin condensate and the like can be mentioned. The position of the sulfonic acid group in the aromatic ring is arbitrary.

Further, in the present invention, the organic acid may be a polymer acid. Examples of such a polymer acid include polyvinyl sulfonic acid, polyvinyl sulfate, polystyrene sulfonic acid, sulfonated styrene-butadiene copolymer, polyallyl sulfonic acid, polymethallyl sulfonic acid, and poly-2-acrylamido-2-methyl. Examples thereof include propanesulfonic acid, polyhalogenated acrylic acid, polyisoprenesulfonic acid, N-sulfoalkylated polyaniline, and nuclear sulfonated polyaniline. A fluoropolymer known as Naphion (registered trademark of DuPont, USA) is also suitably used as the polymer acid.

Further, in the present invention, the organic acid is selected from esters of the above-mentioned organic acids and polyhydroxy compounds.
Those having an acid terminal are also preferred. Such polyhydroxy compounds include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol,
Neopentyl glycol, 1,6-hexanediol, 1,4
-Bis (hydroxytyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, hydroxypivalyl hydroxypivalate, trimethylolethane, trimethylolpropane, 2,2,4-trimethyl-1,3-pentanediol, glycerin, hexanetriol , Tris (2
Polyhydric alcohols such as -hydroxyethyl) isocyanurate or pentaerythryl, polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene tetramethylene glycol, polyoxypropylene tetramethylene glycol or polyoxyethylene polyoxypropylene poly Ring-opening polymerization of polyether glycols such as oxytetramethylene glycol, the above polyhydric alcohols with ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether or allyl glycidyl ether. And the like.

Examples of the solvent of the present embodiment include DMAc (dimethylformamide) and NMP (N-methylpyrrolidone).

Further, the intermediate transfer member of the present embodiment may have another layer in contact with the polyimide layer obtained by the above method. For example, a protective layer may be provided on the side of the polyimide layer that receives toner transfer. Further, a layer having a high frictional force may be provided on the side of the polyimide layer which contacts the driving means. Further, the polyimide layer can be processed mechanically and chemically as needed. For example, mechanical and chemical means, on the side of the polyimide layer that receives the transfer of the toner and the side that contacts the driving means,
For example, the unevenness may be formed by a sand blast method or a chemical etching method. Conversely, if necessary, the surface may be smoothed by using a means such as polishing.

Other components can be added to the above-mentioned coating liquid as needed. For example, it is possible to mix a filler for the purpose of reinforcement. As filler, silica, alumina, insulating filler such as titanium oxide,
Semiconductive fillers such as tin oxide, antimony-doped tin oxide, indium-doped tin oxide, and carbon black can be used. When a semiconductive filler is used, it can be used in the same manner as an insulating filler by setting the addition amount to a percolation threshold or less. When the addition amount of the semiconductive filler is equal to or more than the threshold value, the electrical characteristics of the obtained intermediate transfer member gradually approach the characteristics of a normal semiconductive filler-added intermediate transfer member, which is not preferable. .

The polyaniline constituting the polyimide layer of the intermediate transfer member of the present invention has a number average molecular weight of 4,000 to 4
00,000, more preferably 1
It is between 000 and 200,000.

The polyaniline has a number average molecular weight of 4,000.
When the content is in the range of from 400,000 to 400,000, the film can be appropriately made conductive without impairing the mechanical properties. If the number average molecular weight is less than 4,000, the mechanical properties will be reduced if the resistance value of the obtained film is sufficiently reduced. If the number average molecular weight exceeds 400,000, the solubility of polyaniline decreases, and the surface properties of the obtained film deteriorate, and there is a concern that the surface properties required for an electrophotographic intermediate transfer member cannot be secured. .

The amount of polyaniline in the polyimito layer of the intermediate transfer member is preferably 3% to 30% by weight, more preferably 5% to 20%, and still more preferably 10% to 18%. When the amount of polyaniline in the polyimito layer of the intermediate transfer member is in the range of 3% to 30% by weight, appropriate conductivity and mechanical properties can be achieved at the same time. However, if the amount of polyaniline is less than 3%, the film is not sufficiently semiconductive, and if it exceeds 20%, the mechanical properties and appearance are impaired. .

By adjusting the molecular weight and the amount of polyaniline added,
When the volume resistivity of the intermediate transfer member is 10 ^{7 to} 10 ¹⁵ Ωcm, more preferably 10 ^{9 to} 10 ¹² Ωcm, good transferability can be obtained as an intermediate transfer member for electrophotography.
If the resistivity is less than 10 ⁷ Ωcm, the surface potential of the intermediate transfer member, which is a driving force for transferring the toner during transfer, cannot be sufficiently secured, and toner transfer failure occurs. On the other hand, if the resistivity is higher than 10 ¹⁵ Ωcm, the surface potential of the intermediate transfer member becomes excessively large, and undesired discharge may cause disturbance of the toner image.

The tensile elasticity of the intermediate transfer member of the present invention is 200 kgf
/ mm ² or more. Tensile modulus is 200kgf / m
If it is m ² or more, the elongation at the time of driving by the driving means of the belt is suppressed, the belt movement accuracy, i.e. once the positional accuracy at the time of transporting the toner transferred onto the transfer member to the secondary transfer position Is improved. In this case, the obtained electrophotographic image is preferably obtained by accurately transferring the toner image formed on the photoconductor.

A filler can be added to the intermediate transfer member according to the present invention, and higher mechanical properties can be realized. When the particle size of the filler is 0.1 μm or more and is 以下 or less of the average particle size of the toner used,
The surface properties required for an electrophotographic intermediate transfer member can be secured while exhibiting a reinforcing effect. When the particle size is 0.1 μm or less, the reinforcing effect is not sufficiently exhibited, which is not preferable. If the average particle diameter of the toner used is not less than の, the toner image is disturbed by irregularities on the surface of the intermediate transfer member, which adversely affects the transfer image quality. Also, in this case, it is not preferable because toner cleaning failure occurs due to unevenness.

The filling amount of the filler in the polyimide layer is preferably from 0.1% to 8%, more preferably from 0.1% to 6% in volume fraction. When the filling amount is 0.1% to 8% by volume, the surface properties required for an electrophotographic intermediate transfer member can be secured while also exhibiting a reinforcing effect. If the filling amount is less than 0.1%, the reinforcing effect is not sufficiently exhibited, which is not preferable. On the other hand, if the filling amount exceeds 8%, the toner image is disturbed by irregularities on the surface of the intermediate transfer member, which adversely affects the transfer image quality, and is not preferable because the irregularities cause poor cleaning of the toner.

The humidity expansion coefficient of the intermediate transfer member according to the present invention is 7
The content is preferably 0 ppm / RH% or less. In this case, good performance can be exhibited even when humidity increases during use of the intermediate transfer member, which is preferable. When the humidity expansion rate exceeds 70 ppm / RH%, when the intermediate transfer member is mounted in the apparatus and the humidity increases while the intermediate transfer member is stopped, for example, in a portion held by a roll, While the expansion is regulated, the space between the holding portions can freely expand according to the humidity expansion rate. Therefore, in this case, wrinkles are generated in the intermediate transfer member in order to absorb the difference in expansion. In this state, the surface flatness required for the intermediate transfer member is not ensured, so that a problem in image quality occurs.

Next, a preferred embodiment of an image forming apparatus to which the intermediate transfer member of the present invention is applied will be described with reference to FIG.
In the image forming apparatus according to the present embodiment, the photosensitive drum 1, which is a carrier of the toner image, has BK (black)
A developing unit 5 for supplying toner; a developing unit 6 for supplying Y (yellow) toner; a developing unit 7 for supplying M (magenta) toner; a developing unit 8 for supplying C (cyan) toner; An endless belt-shaped intermediate transfer member 2 that conveys the toner on the toner transfer member 1 from the primary transfer position to the secondary transfer position, and a conductive electrode that is a transfer electrode that transfers the toner on the photosensitive drum 1 to the intermediate transfer member 2 at the primary transfer position At the secondary transfer position of the roll 25, the bias roll 3, which is a transfer electrode provided on the surface of the intermediate transfer member 2 on which the toner image is carried, is opposed to the bias roll 3 with the intermediate transfer member 2 interposed therebetween. A backup roll 22 disposed, an electrode roll 26 that rotates by pressing against the backup roll 22, a support roll 21 that supports the intermediate transfer body 2 and guides the circulation of the intermediate transfer body 2,
23, 24, a belt cleaner 9 for cleaning residual toner on the intermediate transfer body 2, a cleaning blade 31 for cleaning the bias roll 3, a recording medium 41 as a transfer medium, a tray 4 for supplying the recording medium 41, and recording from the tray 4. Feed roll 4 for feeding medium 41
2 and a peeling claw 13 for peeling the recording medium 41 from the intermediate transfer body 2.

The photosensitive drum 1 rotates in the direction of arrow A,
The surface is uniformly charged by a charging unit (not shown). The charged photosensitive drum 1 is irradiated with laser by an image writing unit (not shown) to form an electrostatic latent image of the first color (BK). This electrostatic latent image is visualized by the toner supplied by the developing unit 5, and a toner image T is formed. The toner image T reaches the primary transfer position where the conductive roll 25 is arranged by the rotation of the photosensitive drum 1,
A voltage having a polarity opposite to that of the electric charge of the toner of the toner image T is applied from the conductive roll 25 and electrostatically attracted to the intermediate transfer body 2. Since the intermediate transfer member 2 moves in the direction of arrow B while contacting the surface of the photosensitive drum 1 at the primary transfer position, the toner image T on the photosensitive drum 1 is successively attracted onto the intermediate transfer member 2 with the movement. Primary transfer.

Similarly to the first color toner image T,
A toner image of the second color (Y), a toner image of the third color (M), and a toner image of the fourth color (C) are formed independently on the photosensitive drum 1 at predetermined time intervals. The circulating intermediate transfer body 2 is transferred to a predetermined position on the circulating intermediate transfer body 2 in a precisely superimposed order. The multicolor toner image formed by superimposing the toner images of the first to fourth colors on the intermediate transfer member 2 is transferred to the secondary transfer position where the bias roll 3 is installed by the circulation of the intermediate transfer member 2. Conveyed.

A recording medium 41 is fed between the intermediate transfer member 2 at the secondary transfer position and the bias roll 3 at a predetermined timing by a feed roll 42 from a recording medium bundle stored in the recording medium tray 4. . At the secondary transfer position, the intermediate transfer member 2 on which the multicolor toner image is placed is moved by the bias roll 3 and the backup roll 22 to the recording medium 41.
When a voltage having the same polarity as the polarity of the multicolor toner image is applied from the electrode roll 26 through the backup roll 22 while being pressed against the multicolor toner image, the multicolor toner image is attracted to the recording medium 41. Since the intermediate transfer body 2 moves so as to circulate in the direction of arrow B together with the recording medium 41 at the secondary transfer position, the multi-color toner image on the intermediate transfer body 2 is successively attracted to the recording medium 41 as it moves. The secondary transfer is performed.

The peeling claw 13 is at the retracted position until the primary transfer of the toner images of all colors is completed, and moves to a position in contact with the belt of the intermediate transfer body 2 after the primary transfer. The recording medium 41 to which the multicolor toner image has been transferred is separated from the intermediate transfer body 2 by the separation claw 13 and is conveyed to a fixing device (not shown). The multicolor toner image on the recording medium 41 is pressed / heated by the fixing device and fixed on the recording medium 41. The fixed image is an electrophotographic image finally formed by the image forming apparatus of the present embodiment.

The residual toner of the multicolor toner image remaining on the intermediate transfer body 2 without being transferred to the recording medium 41 is removed by a belt cleaner 9 provided downstream of the secondary transfer position. Further, a cleaning blade 31 made of polyurethane or the like is attached to the bias roll 3 so as to be always in contact with the bias roll 3, and the cleaning blade 31 removes foreign matters such as toner particles and paper dust adhered to the bias roll 3.

[0045]

EXAMPLES Hereinafter, several examples of the present invention and comparative examples with respect to these examples will be described. These examples are all examples, and the description does not limit the scope of the present invention. (Examples 1 to 11 and Comparative Examples 1 to 3) As shown in Table 1, a polyaniline powder and a dopant (an ester of an organic acid and a polyhydroxy compound, having an acid terminal) were added to N-methylpyrrolidone, The mixture was stirred until a uniform solution was obtained, and further degassed to obtain a polyaniline solution (A). To the solution (A), a polyamic acid solution (# 1, # 2 manufactured by DuPont, USA) was added according to Table 1, and after sufficient stirring, degassing was performed to obtain a coating solution. At this time, a filler was added together according to Table 1 as needed. Note that tin oxide is antimony-doped tin oxide. The obtained coating liquid was applied to a stainless steel plate, dried at 120 ° C. for 30 minutes, and then dried at 300 ° C.
For 15 minutes to obtain a film (B). The film thickness at the time of coating was appropriately adjusted such that the film thickness of the obtained film (B) was 80 μm. Film (B) is 530mm long
After being cut into a rectangular shape having a width of 362 mm, the opposite end portions were joined with an adhesive (Super X from Cemedine) to obtain an endless belt (C). The obtained endless belt (C) was evaluated, and the results shown in Tables 1 and 2 were obtained.

[Measurement method] <Number average molecular weight of polyaniline> GPC (gel filtration chromatography) uses a 0.5 wt% solution of LiCl (lithium chloride) in NMP (N-methylpyrrolidone) as a solvent, and is known as a molecular weight in terms of polystyrene. Was measured according to the method described above.

<Volume Resistivity of Intermediate Transfer Body> The formed sheet is cut into about 350 mm × 200 mm to obtain a measurement sample. Draw an auxiliary line that divides this sheet into approximately three equal parts in the long side direction, and calculate the volume resistivity at the approximate center of each rectangle by ADVANT
It is measured using a high resistance meter R8340A manufactured by EST. A UR probe manufactured by Mitsubishi Chemical Corporation is used as a measurement probe. The applied electric field during the measurement is 1.25 kV / mm, and the electric field application time is 30 seconds. Prepare 8 samples, total 2
The average of the results of the four measurements is the volume resistance of the sample,
The difference obtained by dividing the difference between the highest value and the lowest value by 2 is defined as the variation.

<Rate of change in resistance of the intermediate transfer member over time> The formed sheet was cut into a rectangular shape having a length of 530 mm and a width of 362 mm, and the opposite ends were joined with an adhesive (Cemedyne Super X) to be endless. Get the belt. The obtained belt is mounted on an electrophotographic apparatus and 10,000 electrophotographic images are transferred. After the transfer, the belt is removed from the apparatus, and the volume resistivity is measured by the above method. Assuming that the volume resistivity before the test is R0 and the volume resistivity after the test is R1, the resistance change ΔR is given by the following equation. ΔR = log (R0)-log (R1)

<Tensile Elastic Modulus of Intermediate Transfer Body> In the case of a sheet-like intermediate transfer body, in the case of an intermediate transfer body in which the polyimide layer is formed on a substrate, the polyimide layer is peeled off, and then 10 mm width × The sample is cut to a length of 200 mm, and the measurement is performed according to JIS K7127 at a distance between the marked lines of 100 mm and a tensile speed of 10 mm / min to calculate the tensile elastic modulus.

<Humidity Expansion Coefficient of Intermediate Transfer Member> After the polyimide layer was peeled off from the intermediate transfer member in which the polyimide layer was formed on the base material in the sheet-like intermediate transfer member, 25.4 mm The sample is cut into a width × 210 mm length, and is held so that the distance between the chucks is 150 mm. While applying a tension of 70 g / cm to the film, (A) 35 ° C. 35 RH%
(B) The difference in the distance between the chucks when allowed to stand in an environment of 35 ° C. and 85 RH% for 24 hours is measured to the nearest 0.001 mm. Here, assuming that the difference between the chuck distances is D,
The coefficient of humidity expansion H is given by the following equation. H (ppm / RH%) = D (mm) / 145 (mm) /
(85-35) (RH%) The measurement is performed six times in total (A) → (B) three times and (B) → (A) three times, and the average value is taken as the measured value.

Table 1 shows the obtained results.

[Table 1]

Next, the performance as an intermediate transfer member was evaluated from the obtained measurement results. <Resistance uniformity> ◎ ・ ・ ・ Volume resistivity variation ≦ 0.1 (suitable as an intermediate transfer member) × ・ ・ ・ Volume resistivity variation> 0.5 (unsuitable as an intermediate transfer member) <Resistance retention> ◎ ・· rate of change in resistance ≦ 0.1 (intermediate suitable as transfer member) × · · · resistance change rate> 1.5 (unsuitable as an intermediate transfer member) <driving precision> ◎ · · · tensile modulus> 200 kgf / cm ²・ ・ ・: 180 <tensile elastic modulus ≦ 200 kgf / cm ² ×: tensile elasticity ≦ 180 kgf / cm ² <toner transferability> ・ ・ ・: volume resistivity> 7.0 ×: volume resistivity ≦ 7.0

<Toner Cleaning Property> A: The toner on the intermediate transfer member is cleaned by the blade. Δ: Cleaning failure occurs. ×: Cleaning cannot be performed. <Surface smoothness> A: The surface of the intermediate transfer member is smooth. Δ: Irregularities are seen on the surface of the intermediate transfer member, but there is no problem in use. <Wrinkles at high humidity> ◎ ・ ・ ・ from 23 ℃ 55RH% to 28 ℃ 85RH%
When transferred to the environment described above, little or no wrinkles occur on the surface of the intermediate transfer member. Δ: wrinkles occur under the same conditions, but there is no problem in use. ×: Under the same conditions, wrinkles which cause a problem in use occur.

[0054]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the intermediate transfer member according to the present invention exhibits semi-conductivity due to the uniform structure of the polymer blend. It has stable electrical characteristics. Furthermore, the resistance does not change due to various electrical stresses applied in the electrophotographic apparatus.

[0056]

As described above, according to the present invention,
An intermediate transfer member having excellent mechanical properties, little change in performance due to stress during use, and being industrially stable can be provided. Further, according to the present invention, there is provided an intermediate transfer member having surface smoothness and surface flatness required as an intermediate transfer member.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a preferred embodiment of an image forming apparatus to which an intermediate transfer member of the present invention is applied.

[Description of Signs] 1 Photoconductor drum 2 Intermediate transfer member 3 Bias roll 4 Recording medium tray 5 Developing unit (Black) 6 Developing unit (Yellow) 7 Developing unit (Magenta) 8 Developing unit (Cyan) 9 Belt cleaner 13 Peeling Claw 21, 23, 24 Support roll 22 Backup roll 25 Conductive roll 26 Electrode roll 31 Cleaning blade 41 Recording medium 42 Feed roll

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C08L 79/08 (C08L 79/08 79:00) 79:00) A (72) Inventor Morita Chapter 1 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.F-term (reference) FD017 GS00

Claims (9)

[Claims] An intermediate transfer member having a function of receiving a toner, transporting the toner to another place, and holding the toner until the toner is transferred to a recording medium, wherein (A) polyimide is a main constituent material. Has at least a layer,
(B) The intermediate transfer member, wherein the polyimide layer contains polyaniline and a dopant capable of making the polyaniline conductive. 2. The polyaniline having a number average molecular weight of 4.0.
2. The intermediate transfer member according to claim 1, wherein the number of the intermediate transfer member is from 00 to 400,000. 3. The intermediate transfer member according to claim 1, wherein the amount of the polyaniline added to the polyimide layer is 3% to 30% by weight. 4. The intermediate transfer member has a volume resistivity of 10 ^{7 to} 10 ^15.
4. The method according to claim 1, wherein the resistance is Ωcm.
The intermediate transfer member according to any one of the above. 5. The intermediate transfer member has a tensile modulus of 200 kgf.
5 / cm ² or more. 6. The intermediate transfer member according to claim 1, wherein a filler is added to the polyimide layer. 7. The intermediate transfer member according to claim 6, wherein a particle size of the filler is 0.1 μm or more and １ ／ or less of an average particle size of the toner. 8. The intermediate transfer member according to claim 6, wherein a filling amount of the filler in the polyimide layer is 0.1 to 8% in volume fraction. 9. The intermediate transfer member has a humidity expansion coefficient of 70 ppm.
The intermediate transfer member according to any one of claims 1 to 8, wherein the ratio is / RH% or less.