JP2003029439A - Method and device for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method for forming a good image by preventing a defective image such as cracks and black dots, etc., easily occurring in an image forming method using a contact electrification system, and also, to provide an image forming device using the image forming method. SOLUTION: As for the image forming method for forming the image on an electrophotographic photoreceptor through an electrification process, an exposure process and a developing process, the electrophotographic photoreceptor is provided with an intermediate layer of an insulating layer containing N type semiconductor particles and binder and also with Benard cell formed, and at the electrification process, the electrophotographic photoreceptor is electrified by an electrifying member which is brought into contact with the photoreceptor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) used in the field of copying machines and printers, and an image forming method and image forming apparatus using the electrophotographic photosensitive member. , Process cartridges.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors are mainly transferred from inorganic photoreceptors such as Se, arsenic, arsenic / Se alloys, CdS and ZnO to organic photoreceptors which are excellent in pollution and ease of manufacture. Organic photoconductors using various materials have been developed.

In recent years, function-separated type photoconductors in which different materials are responsible for charge generation and charge transport functions have become the mainstream. Among them, a laminated photoconductor in which a charge generation layer and a charge transport layer are laminated is used. Widely used.

In addition, focusing on the electrophotographic process, latent image forming methods are roughly classified into analog image forming using a halogen lamp as a light source and digital image forming using an LED or a laser as a light source. Recently, a digital latent image forming method is rapidly becoming the mainstream as a printer for a hard copy of a personal computer, and also in an ordinary copying machine because of the ease of image processing and the ease of development to a multi-function peripheral.

In digital image formation, a laser, particularly a semiconductor laser or an LED, is used as a light source when writing image information converted into a digital electric signal on a photoreceptor as an electrostatic latent image. However, in forming a latent image with a laser beam, there is known a peculiar image problem that interference fringes are generated due to reflection on the substrate surface.

In digital writing, the writing speed is slow because the exposure beam diameter is small. Therefore, a combination with reversal development is mainly used as a developing method for the exposed portion, but as a problem peculiar to the image forming method using the reversal development, toner is originally formed on a portion where an image is to be formed as a white background portion. It is known that a black spot is generated due to a local defect of the photoconductor, which is a phenomenon in which the toner adheres to cause fog.

On the other hand, the electrophotographic image forming apparatus typically used in the market at present has charging, image exposing, developing, transferring, cleaning and fixing means on the electrophotographic photosensitive member.

The corona discharger is the best known charging member that has been typically used as a member of the charging means. The corona discharger has an advantage that stable charging can be performed. However, since a corona discharger has to apply a high voltage, a large amount of ionized oxygen, ozone, water, nitric oxide compounds, etc. are generated, so that deterioration of an electrophotographic photoreceptor (hereinafter also referred to as a photoreceptor) is caused. There are problems such as inviting people and adversely affecting the human body.

Therefore, recently, the use of a contact charging method which does not use a corona discharger has been studied. Specifically, a voltage is applied to a magnetic brush or a conductive roller, which is a charging member, to contact a photoreceptor, which is a member to be charged, to charge the surface of the photoreceptor to a predetermined potential. When such a contact charging method is used, the voltage can be lowered and the amount of ozone generated can be reduced as compared with the non-contact charging method using a corona discharger. However, as a problem of the contact charging method, the charging roller or the like comes into direct contact with the electrophotographic photosensitive member and rubs the surface of the photosensitive member, so that film peeling or cracking occurs in the photosensitive layer or the intermediate layer, and black spots occur. And easily cause image defects. These problems are likely to occur especially under severe conditions such as high temperature and high humidity and low temperature and low humidity.

In order to solve these problems, a technique of using an intermediate layer in the photoconductor has been developed. For example, an electrophotographic photosensitive member is known in which an intermediate layer is provided between a conductive support and a photosensitive layer, and titanium oxide particles are dispersed in a resin in the intermediate layer. Further, a technique of an intermediate layer containing titanium oxide subjected to surface treatment is also known. For example, iron oxide disclosed in JP-A-4-303846, titanium oxide surface-treated with tungsten oxide, titanium oxide surface-treated with an amino group-containing coupling agent disclosed in JP-A-9-96916, and JP-A-9-258469. Examples thereof include titanium oxide surface-treated with an organic silicon compound and titanium oxide surface-treated with methylhydrogenpolysiloxane described in JP-A-8-328283.

However, even if these techniques are used, in a severe environment of high temperature and high humidity and low temperature and low humidity, the prevention of black spots is still insufficient, or the residual potential rises due to repeated use, and the exposed portion is exposed. There is a problem that the electric potential rises and the image density cannot be sufficiently obtained. Furthermore, JP-A-1
No. 1-344826 proposes an electrophotographic photoreceptor having an intermediate layer using a dendritic titanium oxide surface-treated with a metal oxide or an organic compound. However, according to the results of the additional test of the embodiment disclosed in this patent, the effect of preventing black spots at high temperature and high humidity and low temperature and low humidity is not sufficient. Further, there is no sufficient countermeasure against film peeling between the conductive support and the intermediate layer and film peeling between the intermediate layer and the charge generation layer, which are likely to occur when the contact charging method is used.

On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 3-179362 mentions a method in which a cell structure (benard cell) is generated in the undercoat layer to roughen the surface, but there is a description that it cannot be controlled and image defects occur. is there. JP-A-8-248651
In JP-A No. 1989-242, there is a description that a Benard cell is generated during dip coating of the undercoat layer, the leveling property is deteriorated, and the electrophotographic performance is deteriorated. In general, the occurrence of Benard cells has been regarded as unfavorable and has been reduced.

On the other hand, in JP-A-60-32056 and JP-A-60-252359, there are positively described conductive layers and intermediate layers having Benard cells, the purpose of which is to examine measures against moire. However, there is no mention of the relation with the occurrence of black spots and the effect of improving electrophotographic characteristics.

[0014]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention prevents image defects such as cracks and black spots, which are likely to occur in an image forming method using a contact charging method, and provides a conductive support. An object of the present invention is to provide an image forming method in which the adhesiveness between the body and the intermediate layer or between the intermediate layer and the photosensitive layer is improved, and a good image can be obtained, and an image forming apparatus using the image forming method is provided. It is to be.

[0015]

SUMMARY OF THE INVENTION The present inventors have found that the above-mentioned problems in the image forming method using the contact charging method use an intermediate layer containing N-type semiconductive particles on a conductive support. It has been found that by using a photoreceptor having a Benard cell formed in the intermediate layer, image defects such as black spots, reduction in image density, fog and cracks do not occur, and it can be used for a long period of time. .

The object of the present invention is achieved by the following configurations. 1. In an image forming method of forming an image on an electrophotographic photosensitive member via a charging step, an exposing step and a developing step, the electrophotographic photosensitive member contains N-type semiconductive particles and a binder, and a Benard cell is formed. An image forming method, which comprises an intermediate layer of an insulating layer, and in the charging step, a charging member is brought into contact with the electrophotographic photosensitive member to charge the electrophotographic photosensitive member.

2. 2. The image forming method as described in 1 above, wherein the charging member is a charging roller.

3. 2. The image forming method as described in 1 above, wherein the charging member is a magnetic brush charging device.

4. 1. The N-type semiconductor particles are subjected to surface treatment a plurality of times, and the final surface treatment is a surface treatment with a reactive organosilicon compound.
4. The image forming method according to any one of 3 to 3.

5. 5. The image forming method as described in 4 above, wherein the reactive organosilicon compound is methylhydrogenpolysiloxane.

6. 5. The image forming method as described in 4 above, wherein the reactive organosilicon compound is an organosilicon compound represented by the following general formula (1).

General formula (1) R-Si- (X) ₃ (R represents an alkyl group, an aryl group, X represents a methoxy group, an ethoxy group or a halogen group) 7. 7. The image forming method as described in 6 above, wherein R in the general formula (1) is an alkyl group having 4 to 8 carbon atoms.

8. At least one surface treatment among the plurality of surface treatments is a surface treatment of one or more compounds selected from alumina, silica, and zirconia. The image forming method described.

9. 9. The image forming method as described in any one of 1 to 8 above, wherein the N-type semiconductive particles are surface-treated with an organic silicon compound having a fluorine atom.

10. Item 10. The image forming method described in any one of Items 1 to 9, wherein the N-type semiconductive particles are particles having a number average primary particle size of 10 nm or more and 200 nm or less.

11. 11. The image forming method as described in any one of 1 to 10 above, wherein the N-type semiconductive particles are metal oxide particles.

12. 12. The image forming method described in 11 above, wherein the metal oxide particles are titanium oxide particles.

13. 13. The image forming method described in any one of 1 to 12 above, wherein the binder of the intermediate layer is a polyamide resin.

14. Dry film thickness of the intermediate layer 0.2 to 15
1 μm, any one of the above 1 to 13
The image forming method according to item.

15. 15. The toner according to any one of 1 to 14 above, wherein in the developing step, a toner having a variation coefficient of shape factor of toner particles of 16% or less and a number variation coefficient of number particle size distribution of 27% or less is used. The image forming method described in 1 ..

16. A shape factor of 1.0 to
16. The image forming method described in any one of 1 to 15 above, wherein a toner in which the number of toner particles in the range of 1.6 is 65% by number or more is used.

17. 17. The image forming method described in any one of 1 to 16 above, wherein a toner containing 50% by number or more of toner particles having no corners is used in the developing step.

18. In the developing step, the number average particle size is 3
1 characterized in that a toner having a particle size of ˜8 μm is used
The image forming method according to any one of items 1 to 17.

19. In the developing step, when the particle diameter of the toner particles is D (μm), the natural logarithm lnD is plotted on the horizontal axis, and the horizontal axis is a histogram showing a number-based particle size distribution divided into a plurality of classes at 0.23 intervals. The sum (M) of the relative frequency (m ₁ ) of the toner particles included in the most frequent class and the relative frequency (m ₂ ) of the toner particles included in the next most frequent class is 70%. 19. The image forming method as described in any one of 1 to 18 above, wherein the above toner is used.

20. An image forming apparatus using the image forming method described in any one of 1 to 19 above.

The present invention will be described in detail below. The Benard cell of the present invention means a "Benard cell (convection cell) phenomenon" that occurs in the coating layer when the coating layer is formed, and the coating layer of the intermediate layer dispersion is dried and solidified to form the intermediate layer. In the process of forming the coating layer, that is, in the process of evaporating the solvent contained in the coating layer of the intermediate layer dispersion to solidify the coating layer, the components in the coating layer convect vertically to the coating layer. And a polygonal or partially polygonal surface shape generated by applying surface tension thereto.

The inventors of the present invention utilize the above-mentioned "Benard cell (convection cell) phenomenon" occurring in the coating layer to obtain the intermediate layer, and the intermediate layer containing N-type semiconductive particles and a binder is used. We succeeded in eliminating black spots by forming Benard cells on the surface. Benard cells refer to polygonal or partially polygonal surface shapes, preferably layers containing hexagonal shapes.
In addition, the ratio of hexagons to the polygonal shape is 10 to 1
00% (number basis) is good, preferably 20-100%
Is good. Further, the size of the Benard cell is preferably about 10 to 500 μm measured at the longest part.

The size and depth of the Benard cell in the intermediate layer of the present invention can be controlled by controlling the viscosity of the intermediate layer dispersion liquid,
Surface tension, solvent composition, type, coating amount, film thickness,
This can be done by appropriately selecting the drying conditions and the like. In particular, when N-type semiconducting particles having a relatively small specific gravity, such as titanium oxide particles, are used in the intermediate layer,
It is relatively easy to occur.

The intermediate layer dispersion liquid has a viscosity of 7 to 250.
The use of mPa · s is also preferable for forming a Benard cell. In this viscosity range, convection of the dispersion easily occurs due to evaporation of the solvent in the coating layer. On the other hand, when the dispersion has a high viscosity of more than 250 mPa · s or a low viscosity of less than 7 mPa · s, the solvent contained in the coating layer evaporates and the coating layer is solidified. This is because there is no possibility of convection of the dispersion liquid in the coating layer, or the degree of convection is too low, so that there is a possibility that it will not be formed.

Further, in the intermediate layer of the present invention, it is necessary to coat and dry so that the dry film thickness is 0.2 to 15 μm. The dry film thickness is preferably 0.3 to 10 μm
m, and more preferably 0.5 to 8 μm.

When the dry film thickness is less than 0.2 μm, the coating is used as a driving force for the convection of each component in the coating layer, which is generated during the process in which the solvent contained in the coating layer is evaporated and the coating layer is solidified. The difference in surface tension and the difference in buoyancy between the upper and lower surfaces of the layer are not significant, and it becomes difficult to form a Benard cell on the surface.

If the film thickness is larger than 15 μm, the solvent in the coating layer evaporates due to forced drying in the step of drying the coating layer even after the surface of the coating layer is solidified, and foaming or cracking occurs in the layer. It becomes difficult to form the surface uniformly.

The N-type semiconducting particles used in the present invention are
A fine particle having a property of making a conductive carrier an electron is shown.
That is, the property that the conductive carrier is an electron means that the N
By including the type semiconductive particles in an insulating binder, it is possible to efficiently block the injection of holes from the substrate and to exhibit a property of not blocking electrons from the photosensitive layer.

The N-type semiconductor particles are specifically titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (S).
Although fine particles such as nO ₂ ) can be used, titanium oxide is particularly preferably used in the present invention.

The number average primary particle size of the N-type semiconductor particles used in the present invention is preferably 10 nm or more and 200 nm or less, and more preferably 15 to 150 nm. When the thickness is less than 10 nm, no Benard cell is generated in the intermediate layer, and the effect of preventing black spots from being generated by the intermediate layer is small. On the other hand, if it is larger than 200 nm, the uniformity of the Benard cell is poor, and as a result, black spots also increase. An intermediate layer coating solution using N-type semiconductive particles having a number average primary particle size in the above range has good dispersion stability, and an intermediate layer formed from such a coating solution having a Benard cell is a black spot. In addition to the function of preventing generation, it has good environmental characteristics and has cracking resistance.

The number average primary particle size of the N-type semiconductor particles is
For example, in the case of titanium oxide, it is a measurement value as a Feret direction average diameter obtained by observing 100 particles as primary particles randomly by enlarging by 10,000 times by observation with a transmission electron microscope.

The N-type semiconducting particles used in the present invention may have a dendritic, needle-like, or granular shape. The N-type semiconducting particles having such a shape are, for example, titanium oxide particles. As the crystal type, there are anatase type, rutile type, amorphous type, and the like, but any crystal type may be used, or two or more crystal types may be mixed and used. Among them, the rutile type is the best.

One of the surface treatments performed on the N-type semiconductive particles of the present invention is that the surface treatment is carried out a plurality of times, and the last surface treatment among the plurality of surface treatments is a reactive organosilicon. The surface treatment is performed using a compound. Further, among the plurality of surface treatments, at least one surface treatment is at least one surface treatment selected from alumina, silica, and zirconia, and finally a surface treatment using a reactive organosilicon compound. Is preferably performed.

Alumina treatment, silica treatment, and zirconia treatment are treatments for precipitating alumina, silica, or zirconia on the surface of N-type semiconducting particles. Hydrates of silica, silica and zirconia are also included. Further, the surface treatment of the reactive organic silicon compound means that the reactive organic silicon compound is used in the treatment liquid.

As described above, the surface treatment of N-type semiconducting particles such as titanium oxide particles is performed at least twice, so that the surface of the N-type semiconducting particles is uniformly coated (treated). When the treated N-type semiconducting particles are used in the intermediate layer, the dispersibility of the N-type semiconducting particles such as titanium oxide particles in the intermediate layer is good and the image defects such as black spots do not occur. The photoconductor can be obtained.

Further, it is particularly preferable that the surface treatment is performed a plurality of times using alumina and silica, and then the surface treatment is performed with a reactive organosilicon compound.

The treatment of alumina and silica described above may be carried out at the same time, but especially the treatment of alumina is carried out first.
Next, it is preferable to perform silica treatment. Further, the treatment amount of alumina and silica when the treatment of alumina and silica is performed is preferably such that the amount of silica is larger than that of alumina.

The surface treatment of the N-type semiconductive particles such as titanium oxide described above with a metal oxide such as alumina, silica and zirconia can be carried out by a wet method. For example, silica,
Alternatively, the N-type semiconductive particles that have been subjected to the surface treatment of alumina can be produced as follows.

When titanium oxide particles are used as the N-type semiconductor particles, titanium oxide particles (number average primary particle diameter: 50 n
m) is dispersed in water at a concentration of 50 to 350 g / L to give an aqueous slurry, to which a water-soluble silicate or a water-soluble aluminum compound is added. Then, neutralize by adding an alkali or an acid, silica on the surface of the titanium oxide particles,
Alternatively, alumina is precipitated. Subsequently, filtration, washing and drying are performed to obtain the target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. on the other hand,
When aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

The amount of the metal oxide used in the surface treatment is 0.1 to 5 with respect to 100 parts by mass of the N-type semiconducting particles such as titanium oxide particles in the charged amount during the surface treatment.
0 parts by weight, more preferably 1 to 10 parts by weight of metal oxide is used. Even when the above-mentioned alumina and silica are used, for example, in the case of titanium oxide particles, titanium oxide particles 10
It is preferable to use 1 to 10 parts by mass with respect to 0 parts by mass, and it is preferable that the amount of silica is larger than that of alumina.

The surface treatment with the reactive organosilicon compound, which is performed after the surface treatment with the above metal oxide, is preferably performed by the following wet method.

That is, the titanium oxide treated with the metal oxide is added to a solution prepared by dissolving or suspending the reactive organosilicon compound in an organic solvent or water, and the solution is stirred for several minutes to 1 hour. To do. Then, in some cases, the liquid is subjected to a heat treatment, subjected to a process such as filtration and then dried to obtain titanium oxide particles whose surface is coated with an organosilicon compound. The reactive organic silicon compound may be added to a suspension of titanium oxide dispersed in an organic solvent or water.

In the present invention, the fact that the surface of titanium oxide particles is coated with a reactive organosilicon compound means
Photoelectron spectroscopy (ESCA), Auger electron spectroscopy (Au)
ger), secondary ion mass spectrometry (SIMS), and diffuse reflection FI-IR.

The amount of the reactive organosilicon compound used in the surface treatment is 0 with respect to 100 parts by mass of titanium oxide treated with the metal oxide in the charged amount at the time of the surface treatment. 1 to 50 parts by mass, more preferably 1 to 10 parts by mass. When the amount of surface treatment is less than the above range, the surface treatment effect is not sufficiently imparted, and the dispersibility of titanium oxide particles in the intermediate layer deteriorates.
Further, if it exceeds the above range, the electric performance is deteriorated, and as a result, the residual potential increases and the charging potential decreases.

Examples of the reactive organosilicon compound used in the present invention include compounds represented by the following general formula (2), but any compound that undergoes a condensation reaction with a reactive group such as a hydroxyl group on the surface of titanium oxide can be used. However, it is not limited to the following compounds.

General formula (2) (R) _n -Si- (X) _4-n (wherein Si represents a silicon atom, R represents an organic group in which carbon is directly bonded to the silicon atom, and X represents Represents a hydrolyzable group, and n represents an integer of 0 to 3.) In the organosilicon compound represented by the general formula (2), R
As the organic group in which carbon is directly bonded to silicon represented by, methyl, ethyl, propyl, butyl, pentyl,
Alkyl groups such as hexyl, octyl and dodecyl, aryl groups such as phenyl, tolyl, naphthyl and biphenyl, γ
-Epoxy-containing groups such as glycidoxypropyl, β- (3,4-epoxycyclohexyl) ethyl, γ-acryloxypropyl, (meth) acryloyl group of γ-methacryloxypropyl, γ-hydroxypropyl, 2, Three
-Hydroxyl group containing dihydroxypropyloxypropyl,
Vinyl-containing groups such as vinyl and propenyl, mercapto-containing groups such as γ-mercaptopropyl, γ-aminopropyl, N-
Amino-containing groups such as β (aminoethyl) -γ-aminopropyl, halogen-containing groups such as γ-chloropropyl, 1,1,1-trifluoropropyl, nonafluorohexyl and perfluorooctylethyl, and other nitro and cyano A substituted alkyl group is mentioned. As the hydrolyzable group of X, an alkoxy group such as methoxy and ethoxy, a halogen group,
An acyloxy group may be mentioned.

The organosilicon compound represented by the general formula (2) may be used alone or in combination of two or more kinds.

In the specific compound of the organosilicon compound represented by the general formula (2), when n is 2 or more, a plurality of R
May be the same or different. Similarly, when n is 2 or less, plural Xs may be the same or different. When two or more organosilicon compounds represented by the general formula (2) are used, R and X may be the same or different between the respective compounds.

The following compounds may be mentioned as examples of compounds in which n is 0. Tetrachlorosilane, diethoxydichlorosilane, tetramethoxysilane, phenoxytrichlorosilane, tetraacetoxysilane, tetraethoxysilane, tetraallyloxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrakis (2-methoxyethoxy) silane, tetrabutoxysilane , Tetraphenoxysilane, tetrakis (2-ethylbutoxy) silane, tetrakis (2-ethylhexyloxy) silane and the like.

The following compounds may be mentioned as examples of compounds in which n is 1. That is, trichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, ethyltrichlorosilane, allyltrichlorosilane, n-propyltrichlorosilane, n-butyltrichlorosilane, chloromethyltriethoxysilane, methyltrimethoxysilane, mercaptomethyltrimethoxysilane, Trimethoxyvinylsilane, ethyltrimethoxysilane, 3,3,4
4,5,5,6,6,6-nonafluorohexyltrichlorosilane, phenyltrichlorosilane, 3,3,3-
Trifluoropropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, triethoxysilane, 3
-Mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, benzyltrichlorosilane, methyltriacetoxysilane, chloromethyltriethoxysilane, ethyltriacetoxysilane, phenyltrimethoxysilane, 3-allylthiopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 3-allylaminopropyltrimethoxysilane, propyltriethoxysilane, hexyltrimethoxysilane, 3-aminopropyl Triethoxysilane, 3-methacryloxypropyltrimethoxysilane, bis (ethylmethylketoxime) methoxymethylsilane, pentyltriethoxysilane, octyl Triethoxysilane, a dodecyloxy triethoxy silane and the like.

Examples of the compound in which n is 2 include the following compounds. Dimethyldichlorosilane, dimethoxymethylsilane, dimethoxydimethylsilane, methyl-3,
3,3-trifluoropropyldichlorosilane, diethoxysilane, diethoxymethylsilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3-chloropropyldimethoxymethylsilane, chloromethyldiethoxysilane, diethoxydimethyl Silane, dimethoxy-3-mercaptopropylmethylsilane, 3,3
4,4,5,5,6,6,6-nonafluorohexylmethyldichlorosilane, methylphenyldichlorosilane,
Diacetoxymethylvinylsilane, diethoxymethylvinylsilane, 3-methacryloxypropylmethyldichlorosilane, 3-aminopropyldiethoxymethylsilane, 3- (2-aminoethylaminopropyl) dimethoxymethylsilane, t-butylphenyldichlorosilane,
3-methacryloxypropyldimethoxymethylsilane,
3- (3-cyanopropylthiopropyl) dimethoxymethylsilane, 3- (2-acetoxyethylthiopropyl) dimethoxymethylsilane, dimethoxymethyl-2-
Piperidinoethylsilane, dibutoxydimethylsilane,
3-dimethylaminopropyldiethoxymethylsilane,
Examples include diethoxymethylphenylsilane, diethoxy-3-glycidoxypropylmethylsilane, 3- (3-acetoxypropylthio) propyldimethoxymethylsilane, dimethoxymethyl-3-piperidinopropylsilane, and diethoxymethyloctadecylsilane. To be

Examples of the compound in which n is 3 include the following compounds. Trimethylchlorosilane, methoxytrimethylsilane, ethoxytrimethylsilane, methoxydimethyl-3,3,3-trifluoropropylsilane, 3-
Chloropropylmethoxydimethylsilane, methoxy-3
-Mercaptopropylmethylmethylsilane and the like.

The organosilicon compound represented by the general formula (2) is preferably the organosilicon compound represented by the following general formula (1).

In the general formula (1) R-Si-X ₃ , R is an alkyl group, an aryl group, X is a methoxy group,
Represents an ethoxy group and a halogen group.

In the organosilicon compound represented by the general formula (1), an organosilicon compound in which R is an alkyl group having 4 to 8 carbon atoms is more preferred, and a specific preferred compound example is trimethoxy. Examples thereof include n-butylsilane, trimethoxy i-butylsilane, trimethoxyhexylsilane, and trimethoxyoctylsilane.

As a preferred reactive organosilicon compound used for the final surface treatment, a polysiloxane compound can be mentioned. The molecular weight of the polysiloxane compound is 1000.
Generally, those of up to 20000 are easily available, and the black spot prevention function is also good.

Particularly, when methylhydrogenpolysiloxane is used for the final surface treatment, good effects can be obtained.

Another one of the surface treatments of titanium oxide of the present invention is titanium oxide particles surface-treated with an organosilicon compound having a fluorine atom. It is preferable to carry out the surface treatment with the organosilicon compound having a fluorine atom and the above-mentioned wet method.

That is, the organic silicon compound having a fluorine atom is dissolved or suspended in an organic solvent or water, untreated titanium oxide is added thereto, and such a solution is stirred for about several minutes to 1 hour. Then, the mixture is mixed, and if necessary subjected to heat treatment, dried through a step such as filtration to coat the titanium oxide surface with an organosilicon compound having a fluorine atom. The organosilicon compound having a fluorine atom may be added to a suspension prepared by dispersing titanium oxide in an organic solvent or water.

Incidentally, the fact that the surface of the titanium oxide is coated with an organic silicon compound having a fluorine atom means that
Photoelectron spectroscopy (ESCA), Auger electron spectroscopy (Au)
ger), secondary ion mass spectrometry (SIMS), and diffuse reflection FI-IR.

The organosilicon compound having a fluorine atom used in the present invention is 3,3,4,4,5,5,5.
6,6,6-nonafluorohexyltrichlorosilane,
3,3,3-trifluoropropyltrimethoxysilane, methyl-3,3,3-trifluoropropyldichlorosilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3,3,4,4,5 , 5, 6, 6,
6-nonafluorohexyl methyl dichlorosilane etc. are mentioned.

Next, the surface-treated titanium oxide particles and other N-type semiconducting particles (hereinafter also referred to as surface-treated N-type semiconducting particles. Further, particularly, surface-treating titanium oxide is used. The structure of the intermediate layer in which particles are also referred to as surface-treated titanium oxide) will be described.

The intermediate layer of the present invention is a conductive liquid prepared by dispersing surface-treated N-type semiconductive particles such as surface-treated titanium oxide obtained by performing the above-mentioned surface treatment a plurality of times in a solvent together with a binder resin. It is prepared by coating on a support.

The intermediate layer of the present invention is provided between the conductive support and the photosensitive layer, and improves the adhesiveness between the conductive support and the photosensitive layer, and a barrier function for preventing charge injection from the support. Have. As the binder resin for the intermediate layer, a thermosetting resin such as a polyamide resin, a vinyl chloride resin, a vinyl acetate resin, a polyvinyl acetal resin, a polyvinyl butyral resin, a polyvinyl alcohol resin, a melamine resin, an epoxy resin or an alkyd resin, or a resin thereof. And a copolymer resin containing two or more of the repeating units of. Among these binder resins, a polyamide resin is particularly preferable, and an alcohol-soluble polyamide such as copolymerized or methoxymethylolated is particularly preferable.

The amount of the surface-treated N-type semiconductive particles of the present invention dispersed in the binder resin is, for example, in the case of surface-treated titanium oxide, 10 to 10,000 parts by mass based on 100 parts by mass of the binder resin. Parts, preferably 50-1,
000 parts by mass. By using the surface-treated titanium oxide in this range, the dispersibility of the titanium oxide can be kept good, and a good intermediate layer without black spots can be formed.

The intermediate layer of the present invention is substantially an insulating layer. Here, the insulating layer has a volume resistance of 1 × 10 ⁸ to 10 ¹⁵
Ω · cm. The volume resistance of the intermediate layer of the present invention is preferably 1 × 10 ⁹ to 10 ¹⁴ Ω · cm, more preferably,
2 × 10 ⁹ to 1 × 10 ¹³ Ω · cm is preferable. The volume resistance can be measured as follows.

Measurement conditions: JIS: C2318-1975
According to. Measuring instrument: Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd. Measuring condition: Measuring probe HRS Applied voltage: 500 V Measuring environment: 20 ± 2 ° C., 65 ± 5 RH% If the volume resistance is less than 1 × 10 ⁸ , the charge blocking property of the intermediate layer is deteriorated. However, the generation of black spots increases and the potential holding property of the electrophotographic photosensitive member also deteriorates, so that good image quality cannot be obtained. On the other hand, if it is larger than 10 ¹⁵ Ω · cm, the residual potential is likely to increase due to repeated image formation, and good image quality cannot be obtained.

The coating solution for the intermediate layer prepared to form the intermediate layer of the present invention is the surface-treated N such as the surface-treated titanium oxide.
It is composed of mold semiconductive particles, a binder resin, a dispersion solvent, and the like, and as the dispersion solvent, the same solvent as that used in the preparation of other photosensitive layers is appropriately used.

That is, the solvent or dispersion medium used for forming the intermediate layer, photosensitive layer and other resin layers of the present invention is n-
Butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methylethylketone, methylisopropylketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1 , 2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, Methyl cellosolve and the like can be mentioned.

The solvent for the coating liquid for the intermediate layer is not limited to these, but methanol, ethanol, butanol, 1-propanol, isopropanol and the like are preferably used. Further, these solvents can be used alone or as a mixed solvent of two or more kinds.

As the solvent for coating the intermediate layer, it is preferable to use a mixed solvent of methanol and a linear alcohol having high resin solubility in order to prevent uneven drying during coating of the intermediate layer. The ratio of the linear alcohol to the methanol is 1 to 0.05 by volume.
A mixture of 6 is preferable. By using the coating solvent as a mixed solvent in this way, the evaporation rate of the solvent can be appropriately maintained, and the occurrence of image defects due to uneven drying during coating can be suppressed.

As a dispersing means for the surface-treated titanium oxide used for preparing the coating solution for the intermediate layer, any dispersing means such as a sand mill, a ball mill or ultrasonic dispersing may be used.

As the coating processing method for producing the electrophotographic photosensitive member of the present invention including the intermediate layer, dip coating,
Although coating processing methods such as spray coating and circular amount regulation type coating are used, the coating processing on the upper layer side of the photosensitive layer does not dissolve the lower layer film as much as possible, and in order to achieve uniform coating processing, spray coating or circular coating It is preferable to use a coating processing method such as regulated coating (a circular slide hopper is a typical example). Regarding the spray coating, for example, JP-A-3-
No. 90250 and JP-A-3-269238, and the circular amount control type coating is described in detail, for example, in JP-A-58-189061.

Next, the constitution of the photosensitive member preferably used in the present invention other than the intermediate layer will be described.

The photoconductor of the present invention can be applied to an inorganic photoconductor using selenium, amorphous silicon or the like.
For the purpose of the present invention, it is preferable to apply the intermediate layer and surface layer of the present invention to an organic electrophotographic photoreceptor (also referred to as an organic photoreceptor).

In the present invention, the organic photoreceptor means an electrophotographic photoreceptor constituted by giving an organic compound at least one of a charge generating function and a charge transporting function which is essential for the construction of the electrophotographic photoreceptor. However, it includes all known organic electrophotographic photoreceptors such as a photoreceptor formed of a known organic charge generating material or an organic charge transporting material, and a photoreceptor including a polymer complex having a charge generating function and a charge transporting function.

The layer structure of the organic photoreceptor is not particularly limited, but a charge generation layer, a charge transport layer, or a charge generation / charge transport layer (a layer having the functions of charge generation and charge transport in the same layer).
It is preferable to adopt a constitution in which a photosensitive layer such as the above and a surface layer are coated thereon. Further, since the surface layer of the present invention has the function of a protective layer and the function of transporting charges, it may be used instead of the charge transporting layer.

The specific constitution of the photoconductor used in the present invention will be described below. Conductive Support In an electrophotographic photosensitive member having a photosensitive layer provided on an aluminum drum base (also referred to as a support) that is most often used at present, the conductive base layer of the drum base itself also serves as the conductive layer. Besides, the conductive layer may not be provided. However, in the case of a photoreceptor using a flexible belt support as in the present invention, the support is usually insulative, and in this case, it is necessary to separately apply a conductive layer.

As the method of forming the conductive layer, aluminum or I is used.
Examples include those obtained by vapor deposition or sputtering of metals or metal oxides such as TO (indium tin oxide), and those obtained by forming a coating film of a conductive resin of a mixture of ITO or alumina conductive fine particles and resin. .

The material for the belt-shaped photoreceptor support that can be used in the present invention may be a generally known engineering plastic base, and is not particularly limited, and examples thereof include polyethylene terephthalate and polyethylene. Examples thereof include naphthalate, polyetherimide, polyethersulfone, polycarbonate, polyarylate and the like. Further, the thickness of the support is 50 to 100 μm in order to balance rigidity and flexibility. The electric resistance of the conductive layer is 10 ^{3 at} room temperature.
Ωcm or less is preferable.

Intermediate Layer In the present invention, the above-mentioned intermediate layer having a barrier function is provided between the conductive support and the photosensitive layer.

Photosensitive Layer The photosensitive layer structure of the photoconductor of the present invention may be a photosensitive layer structure of a single layer structure in which one layer has a charge generating function and a charge transporting function on the above-mentioned intermediate layer, but it is more preferable that the intermediate layer is photosensitive. It is preferable that the function of the layer is separated into a charge generation layer (CGL) and a charge transport layer (CTL). By adopting a constitution in which the functions are separated, the increase in residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negative charging photoreceptor, the charge generation layer (C
GL) and a charge transport layer (CTL) thereon. In the case of the photoconductor for positive charging, the order of the layers is the reverse of that of the photoconductor for negative charging. The most preferable photosensitive layer structure of the present invention is a negatively charged photosensitive member structure having the above-mentioned function separation structure.

The constitution of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below. Charge Generation Layer The charge generation layer contains a charge generation material (CGM). If necessary, a binder resin and other additives may be contained as other substances.

As the charge generating substance (CGM), a known charge generating substance (CGM) can be used. For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azurenium pigment or the like can be used. Among these, CGM that can minimize the increase in residual potential with repeated use
Has a steric structure and a potential structure capable of forming a stable aggregation structure among a plurality of molecules, and specific examples thereof include a phthalocyanine pigment and a perylene pigment CGM having a specific crystal structure. For example, the Bragg angle 2θ with respect to Cu-Kα rays
CGMs such as titanyl phthalocyanine having a maximum peak at 27.2 ° and benzimidazole perylene having a maximum peak at 22.4 at 27.2 have almost no deterioration due to repeated use, and the residual potential increase can be reduced.

When a binder is used as a CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferable resin is formal resin, butyral resin, silicone resin, silicone modified butyral resin, phenoxy resin. Resin etc. are mentioned. The ratio of the binder resin to the charge generating substance is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential due to repeated use can be minimized. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.

Charge Transport Layer The charge transport layer contains a charge transport material (CTM) and a binder resin for dispersing CTM to form a film. Other substances may optionally contain additives such as antioxidants.

As the charge transport material (CTM), a known charge transport material (CTM) can be used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer. Among these, CTM that can minimize the increase in residual potential due to repeated use has high mobility and has a characteristic that the difference in ionization potential with CGM to be combined is 0.5 (eV) or less, and preferably 0. It is 0.25 (eV) or less.

The ionization potentials of CGM and CTM are measured by a surface analyzer AC-1 (manufactured by Riken Keiki Co., Ltd.).

Examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd. Resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of the repeating units of these resins. In addition to these insulating resins, poly-
Examples include polymer organic semiconductors such as N-vinylcarbazole.

The most preferable binder for these CTLs is a polycarbonate resin. Polycarbonate resin is most preferable in improving dispersibility of CTM and electrophotographic characteristics. The ratio of the binder resin to the charge transport material is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 10-40 μm.

Surface Layer By providing the siloxane resin layer of the present invention as the surface layer of the photoconductor, a photoconductor having the most preferable layer constitution of the present invention can be obtained.

In the above, the most preferable layer constitution of the photoconductor of the present invention is exemplified, but in the present invention, a photoconductor layer constitution other than the above may be used.

Next, the toner used in the present invention will be described. The toner is preferably a polymerized toner in which the particle size distribution of individual toner particles and the shape are relatively uniform. Here, the polymerized toner means a toner obtained by forming a resin of a binder for a toner and forming a toner shape by polymerizing a raw material monomer of the binder resin and subsequent chemical treatment. More specifically, it means a toner obtained through a polymerization reaction such as suspension polymerization and emulsion polymerization and, if necessary, a fusion process of particles that are carried out after the polymerization reaction.

The polymerized toner used in the image forming method of the present invention is preferably a toner having a specific shape. The polymerized toner that can be preferably used in the present invention will be described below.

In the digital image forming method for developing a dot image, it is preferable to use a toner having a small variation in shape factor and particle size distribution for development in order to enhance the sharpness of the image and obtain a good image. That is, a toner having a smaller variation can more accurately reproduce a fine dot image and is less likely to cause filming that causes image defects such as black spots.

As a result of examination from the above viewpoints, by using a toner in which the variation coefficient of the shape factor of the toner is 16% or less and the variation coefficient of the number particle size distribution of the toner is 27% or less, It has been found that it is possible to form a high-quality image over a long period of time with excellent cleaning properties and fine line reproducibility.

Preferred polymerized toners applicable to the present invention include toner particles having a shape factor in the range of 1.2 to 1.6 of 65% by number or more, and a variation coefficient of the shape factor of 1.
To use a toner that is 6% or less. It has been found that even if such a polymerized toner is used, excellent cleaning performance is exhibited in the present invention.

Further, by using toner particles having no corners of 50% by number or more and controlling the number variation coefficient in the number particle size distribution to be 27% or less, excellent cleaning property, fine line reproducibility and high quality are obtained. The image quality can be formed over a long period of time.

The shape factor of the toner of the present invention is represented by the following formula and represents the degree of roundness of toner particles.

Shape factor = ((maximum diameter / 2) ² × π) / projected area Here, the maximum diameter means that when a projected image of a toner particle on a plane is sandwiched by two parallel lines, the parallel line. Refers to the width of the particles at which the interval is maximum. The projected area means the area of the projected image of the toner particles on the plane.

In the present invention, this shape factor is determined by taking a photograph of toner particles magnified 2000 times with a scanning electron microscope, and then using this photograph, "SCANNING" is taken.
It was measured by analyzing a photographic image using "IMAGE ANALYZER" (manufactured by JEOL Ltd.). At this time, the shape factor of the present invention was measured by the above calculation formula using 100 toner particles.

The preferable polymerized toner of the present invention is that the number of toner particles having a shape factor of 1.2 to 1.6 is 65% by number or more, and more preferably 7
It is 0% by number or more.

When the number of toner particles having the shape factor in the range of 1.2 to 1.6 is 65% by number or more, the triboelectrification property in the developer carrying member becomes more uniform, and the excessively charged toner is obtained. Is not accumulated and the toner is more easily exchanged than on the surface of the developer transport member, so that problems such as development ghost are less likely to occur. Further, the toner particles are less likely to be crushed, the contamination of the charging member is reduced, and the charging property of the toner is stabilized.

The method of controlling the shape factor is not particularly limited. For example, a method of spraying toner particles in a hot air stream, a method of repeatedly applying mechanical energy by impact force in a gas phase in a gas phase, or a method of adding a toner to a solvent that does not dissolve toner to give a swirling flow, etc. To prepare a toner having a shape factor of 1.2 to 1.6, and add it to a normal toner so as to be within the range of the present invention. Also, controlling the overall shape at the stage of preparing a so-called polymerization toner,
There is a method in which a toner having a shape factor of 1.0 to 1.6 or 1.2 to 1.6 is similarly added to an ordinary toner to prepare the toner.

The variation coefficient of the shape factor of the polymerized toner preferably used in the present invention is calculated by the following formula.

Coefficient of variation = [S / K] × 100 (%) [In the formula, S represents the standard deviation of the shape factors of 100 toner particles, and K represents the average value of the shape factors. The variation coefficient of the shape factor is 16% or less, preferably 14% or less. When the variation coefficient of the shape factor is 16% or less, the voids of the transferred toner layer are reduced, the fixability is improved, and the offset is less likely to occur. In addition, the charge amount distribution becomes sharp and the image quality is improved.

In order to uniformly control the shape factor and the variation coefficient of the shape factor of the toner without extremely lot-to-lot variation, the toner is formed in the steps of polymerizing, fusing and controlling the shape of resin particles (polymer particles). An appropriate process end time may be determined while monitoring the characteristics of certain toner particles (colored particles).

Monitoring means that a measuring device is installed in-line and the process conditions are controlled based on the measurement result. That is, in the case of a polymerization toner in which measurement of a shape or the like is incorporated inline, for example, a resin toner is formed by associating or fusing resin particles in an aqueous medium, the shape and the particle size are measured while performing sequential sampling in the steps such as fusing. Is measured, and the reaction is stopped when the desired shape is obtained.

The monitoring method is not particularly limited, but a flow type particle image analyzer FPIA-
2000 (manufactured by Toa Medical Electronics Co., Ltd.) can be used. This device is suitable because the shape can be monitored by performing image processing in real time while passing the sample liquid. That is, a pump or the like is used from the reaction field to constantly monitor and measure the shape and the like, and the reaction is stopped when the desired shape or the like is obtained.

The number particle size distribution and the number variation coefficient of the toner are measured with a Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co.). In the present invention, a Coulter Multisizer was used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting the particle size distribution and a personal computer were connected and used.
The aperture used in the Coulter Multisizer was 100 μm, and the volume and number of toner particles of 2 μm or more were measured to calculate the particle size distribution and average particle size. The number particle size distribution represents the relative frequency of the toner particles with respect to the particle size, and the number average particle size represents the median diameter in the number particle size distribution.

The number variation coefficient in the number particle size distribution of toner is calculated from the following formula. Number variation coefficient = [S / Dn] × 100 (%) [In the formula, S represents the standard deviation in the number particle size distribution, and D
n indicates a number average particle diameter (μm). The toner number variation coefficient is 27% or less, preferably 25% or less. When the number variation coefficient is 27% or less, the voids of the transferred toner layer are reduced, the fixing property is improved, and the offset hardly occurs. Further, the charge amount distribution becomes sharp, the transfer efficiency is improved, and the image quality is improved.

The method of controlling the number variation coefficient is not particularly limited. For example, a method of classifying toner particles by wind force can be used, but classification in a liquid is effective for reducing the number variation coefficient. As a method of classifying in this liquid, there is a method of controlling the number of revolutions and separately collecting and preparing toner particles according to the difference in sedimentation speed caused by the difference in toner particle diameter.

Particularly when the toner is produced by the suspension polymerization method, the classification operation is indispensable in order to keep the number variation coefficient in the number particle size distribution at 27% or less. In the suspension polymerization method,
Before the polymerization, it is necessary to disperse the polymerizable monomer into an oil droplet having a desired size as a toner in an aqueous medium. That is, the large oil droplets of the polymerizable monomer are repeatedly mechanically sheared by a homomixer or a homogenizer to reduce the oil droplets to the size of toner particles. In the method of different shearing, the number particle size distribution of the obtained oil droplets becomes wide, and therefore,
The toner obtained by polymerizing this also has a wide particle size distribution. For this reason, classification operation is essential.

The toner particles having no corners are toner particles that do not substantially have a protrusion where electric charges are concentrated or a protrusion that is easily worn by stress, that is, as shown in FIG. In addition, when the major axis of the toner particles T is L, a circle C having a radius (L / 10) is in contact with the peripheral line of the toner particles T at one point, and when the inside is rolled, the circle C When the toner does not substantially protrude outside the toner T, it is referred to as “cornerless toner particles”. The term “when substantially not protruding” means a case where there is one or less protrusions with protruding circles. Also, "long diameter of toner particles"
The term "means the width of a particle in which the distance between the parallel lines is maximum when the projected image of the toner particle on the plane is sandwiched by two parallel lines. Note that FIGS. 1B and 1C show projected images of toner particles having corners, respectively.

The toner having no corners was measured as follows. First, an enlarged photograph of toner particles is taken with a scanning electron microscope and further enlarged to obtain a photographic image at 15,000 times. Then, the presence or absence of the above-mentioned corner is measured for this photographic image. This measurement was performed on 100 toner particles.

In the toner of the present invention, the proportion of toner particles having no corners is 50 number% or more, preferably 70 number% or more. When the ratio of the toner particles having no corners is 50% by number or more, the generation of fine particles is less likely to occur due to the stress with the developer transport member and the like,
It is possible to prevent the presence of toner with excessive adhesion to the surface of the developer transport member, suppress contamination of the developer transport member, and make the charge amount sharp. Further, the toner particles that are easily worn or broken and the toner particles having a portion where the electric charge is concentrated are reduced, the charge amount distribution becomes sharp, the chargeability becomes stable, and good image quality can be formed for a long time.

The method for obtaining the toner without corners is not particularly limited. For example, as described above as a method of controlling the shape factor, a method of spraying toner particles in a hot air flow, a method of repeatedly applying mechanical energy due to impact force in a gas phase, or a method of dissolving toner It can be obtained by adding it to a solvent that does not contain it and imparting a swirling flow.

In the polymerization toner formed by associating or fusing resin particles, the surface of the fused particles has many irregularities at the step of stopping the fusion, and the surface is not smooth. The toner having no corners can be obtained by appropriately adjusting the conditions such as the temperature, the rotation speed of the stirring blade, and the stirring time. These conditions vary depending on the physical properties of the resin particles, but for example, by setting the glass transition temperature of the resin particles or higher to a higher rotation speed, the surface becomes smooth and toner without corners can be formed.

The particle diameter of the toner of the present invention is preferably 3 to 8 μm in number average particle diameter. When the toner particles are formed by a polymerization method, this particle size can be controlled by the concentration of the aggregating agent, the amount of the organic solvent added, the fusing time, and the composition of the polymer itself.

By having the number average particle diameter of 3 to 8 μm, it is possible to reduce the presence of excessively adherent toner or toner having low adherence to the developer conveying member in the fixing step, and to improve the developability. It can be stabilized for a long period of time, the transfer efficiency is improved, the halftone image quality is improved, and the image quality of fine lines, dots, etc. is improved.

As the polymerized toner preferably used in the present invention, when the particle diameter of the toner particles is D (μm), the natural logarithm lnD is plotted on the horizontal axis, and the horizontal axis is divided into a plurality of classes at intervals of 0.23. in histogram showing the particle size distribution of number criteria, the relative frequency of the toner particles contained in the modal class (m _1), the relative frequency of the toner particles contained in the following frequent the rank of the modal class (m ₂ ) And (M) is 7
The toner is preferably 0% or more.

When the sum (M) of the relative frequency (m ₁ ) and the relative frequency (m ₂ ) is 70% or more, the dispersion of the particle size distribution of the toner particles becomes narrow, so that the toner is used in the image forming process. By using it, the occurrence of selective development can be surely suppressed.

In the present invention, the histogram showing the number-based particle size distribution has a natural logarithm lnD (D: particle size of individual toner particles) in a plurality of classes (0 to 0) at intervals of 0.23.
0.23: 0.23 to 0.46: 0.46 to 0.69:
0.69 to 0.92: 0.92 to 1.15: 1.15
1.38: 1.38 to 1.61: 1.61 to 1.84:
1.84-2.07: 2.07-2.30: 2.30-
2.53: 2.53 to 2.76 ...), which is a histogram showing a number-based particle size distribution, and the histogram shows particle size data of a sample measured by a Coulter Multisizer according to the following conditions. Is transferred to a computer via an I / O unit and is created by the particle size distribution analysis program in the computer.

[Measurement Conditions] (1) Aperture: 100 μm (2) Sample Preparation Method: Electrolyte Solution [ISOTON R-1
1 (manufactured by Coulter Scientific Japan)
An appropriate amount of a surfactant (neutral detergent) is added to 50 to 100 ml and stirred, and 10 to 20 mg of a measurement sample is added thereto. This system is prepared by subjecting it to an ultrasonic disperser for 1 minute.

Among the methods for controlling the shape factor, the polymerized toner is preferable because it is a simple production method, and the surface uniformity is superior to the pulverized toner.

The toner of the present invention is obtained by emulsion polymerization of a monomer in a suspension polymerization method or in a liquid containing an emulsion containing necessary additives.
It can be manufactured by a method in which finely divided polymer particles are produced, and thereafter, an organic solvent, an aggregating agent and the like are added and associated. At the time of association, a method of preparing by mixing with a dispersion liquid such as a release agent or a colorant necessary for the constitution of the toner to allow association, or dispersing a toner constituent component such as a release agent or a colorant in a monomer Then, a method of emulsion polymerization may be used. Here, the association means that a plurality of resin particles and colorant particles are fused.

The aqueous medium referred to in the present invention means one containing at least 50% by mass of water.

That is, various constituent materials such as a colorant and, if necessary, a releasing agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, and an ultrasonic dispersion are added. Various constituent materials are dissolved or dispersed in the polymerizable monomer by a machine or the like. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in an oil droplet having a desired size as a toner in a water-based medium containing a dispersion stabilizer by using a homomixer or a homogenizer. Then, the stirring mechanism is transferred to a reaction device which is a stirring blade described later and heated to allow the polymerization reaction to proceed. After the completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare a toner.

Further, as a method of producing the toner of the present invention, a method of preparing by associating or fusing resin particles in an aqueous medium can be mentioned. This method is not particularly limited, but for example, JP-A-5-26
The methods shown in JP-A-5252, JP-A-6-329947 and JP-A-9-15904 can be mentioned. That is, a method of associating a plurality of resin particles and dispersed particles of a constituent material such as a colorant, or a plurality of fine particles composed of a resin and a colorant, in particular, after dispersing these in water with an emulsifier, the critical aggregation concentration At the same time as salting out by adding the aggregating agent above, while gradually growing the particle size while forming fused particles by heat fusion above the glass transition temperature of the polymer itself formed, the target particle size and After that, a large amount of water is added to stop the particle size growth, and the surface of the particles is smoothed while heating and stirring to control the shape, and the particles are heated and dried in a fluid state in a water-containing state. Can be formed. Here, an organic solvent that is infinitely soluble in water may be added simultaneously with the coagulant.

The polymerizable monomer used for the resin is styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-. Dichlorostyrene,
p-phenylstyrene, p-ethylstyrene, 2,4-
Dimethyl styrene, p-tert-butyl styrene, p
-N-hexyl styrene, pn-octyl styrene,
pn-nonylstyrene, pn-decylstyrene, p
Styrene or styrene derivative such as -n-dodecyl styrene, methyl methacrylate, ethyl methacrylate,
N-butyl methacrylate, isopropyl methacrylate,
Methacrylate ester derivatives such as isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate. , Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate,
Acrylic ester derivatives such as n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate and phenyl acrylate, olefins such as ethylene, propylene and isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide , Vinyl fluoride, vinylidene fluoride, and other halogen-based vinyls, vinyl propionate, vinyl acetate, vinyl benzoate, and other vinyl esters, vinyl methyl ether, vinyl ethyl ether, and other vinyl ethers, vinyl methyl ketone, vinyl ethyl ketone , Vinyl ketones such as vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone, vinyl compounds such as vinyl naphthalene and vinyl pyridine, acrylonitrile, Acrylonitrile, there are acrylic acid or methacrylic acid derivatives such as acrylamide. These vinyl monomers can be used alone or in combination.

Further, it is more preferable to use, as the polymerizable monomer constituting the resin, those having an ionic dissociative group in combination. For example, those having a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of the monomer, and specifically, acrylic acid, methacrylic acid,
Maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl Methacrylate,
3-chloro-2-acid phosphooxypropyl methacrylate and the like can be mentioned.

Further, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate,
It is also possible to use a polyfunctional vinyl such as neopentyl glycol diacrylate to form a resin having a crosslinked structure.

These polymerizable monomers can be polymerized by using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. As this oil-soluble polymerization initiator, 2,2'-azobis- (2,4
-Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvalero Azo-based or diazo-based polymerization initiators such as nitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide. , Dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-
Examples include peroxide polymerization initiators such as (4,4-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine, and polymer initiators having a peroxide in the side chain. .

When the emulsion polymerization method is used, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetic acid salts, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

Examples of the dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate. , Barium sulfate,
Examples thereof include bentonite, silica and alumina. Furthermore, polyvinyl alcohol, gelatin, methyl cellulose, sodium dodecylbenzene sulfonate, ethylene oxide adduct, higher alcohol sodium sulfate, and the like which are commonly used as surfactants can be used as the dispersion stabilizer.

As the excellent resin in the present invention, those having a glass transition point of 20 to 90 ° C. are preferable and a softening point of 8 is obtained.
It is preferably 0 to 220 ° C. The glass transition point is measured by a differential calorimetric method, and the softening point can be measured by a Koka type flow tester. Furthermore, these resins have a number average molecular weight (Mn) of 10 as measured by gel permeation chromatography.
00-100,000, 200 in weight average molecular weight (Mw)
It is preferably 0 to 1,000,000. Furthermore, as the molecular weight distribution, Mw / Mn is 1.5 to 100, and particularly 1.8.
The thing of -70 is preferable.

The aggregating agent to be used is not particularly limited, but one selected from metal salts is preferably used. Specifically, monovalent metals such as salts of alkali metals such as sodium, potassium and lithium, divalent metals such as alkaline earth metal salts such as calcium and magnesium, divalent metals such as manganese and copper. Salt of
Examples thereof include salts of trivalent metals such as iron and aluminum, and specific salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate and the like. You can
These may be used in combination.

It is preferable to add these coagulants at a critical coagulation concentration or higher. This critical coagulation concentration is an index relating to the stability of the aqueous dispersion, and indicates the concentration at which coagulation occurs when a coagulant is added. This critical aggregation concentration is
It greatly changes depending on the emulsified component and the dispersant itself. For example, Seizo Okamura et al., "Polymer Chemistry 1"
7, 601 (1960) edited by The Society of Polymer Science, Ltd., etc., and a detailed critical aggregation concentration can be obtained. As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ (zeta) potential of the dispersion is measured, and the salt concentration at which this value changes is determined as the critical aggregation concentration. You can also ask.

The amount of the aggregating agent added may be a critical coagulation concentration or higher, but is preferably 1.2 times the critical coagulation concentration or higher.
It is more preferable to add 1.5 times or more.

The infinitely soluble solvent means a solvent infinitely soluble in water, and a solvent which does not dissolve the resin formed in the present invention is selected as this solvent.
Specifically, methanol, ethanol, propanol,
Examples thereof include alcohols such as isopropanol, t-butanol, methoxyethanol, butoxyethanol, nitriles such as acetonitrile, and ethers such as dioxane. Particularly, ethanol, propanol and isopropanol are preferable.

The amount of the solvent that dissolves infinitely is 1 to 100% by volume with respect to the polymer-containing dispersion liquid to which the flocculant is added.
Is preferred.

In order to make the shape uniform, it is preferable to prepare colored particles, and after filtering, slurry in which 10% by mass or more of water is present is fluidized and dried. At this time, in particular, Those having a polar group in the polymer are preferred. It is considered that the reason for this is that since the existing water exerts an effect of swelling the existing water to some extent with respect to the polymer having the polar group, the homogenization of the shape is particularly likely to occur.

The toner of the present invention contains at least a resin and a colorant, but may contain a releasing agent which is a fixing property improving agent, a charge control agent and the like, if necessary. Further, an external additive composed of inorganic fine particles, organic fine particles or the like may be added to the toner particles containing the resin and the colorant as main components.

As the colorant used in the toner of the present invention, carbon black, magnetic materials, dyes, pigments and the like can be optionally used. Examples of the carbon black include channel black, furnace black, acetylene black,
Thermal black, lamp black, etc. are used. Ferromagnetic metals such as iron, nickel, and cobalt as magnetic materials,
Alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys containing no ferromagnetic metals but exhibiting ferromagnetism by heat treatment, such as manganese-copper-
Aluminum, manganese-copper-tin, and other types of alloys called Heusler alloys, chromium dioxide, and the like can be used.

As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 1
22, C.I. I. Solvent Yellow 19, 44, 7
7, ibid 79, ibid 81, ibid 82, ibid 93, ibid 98, ibid 10
3, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 9
5 and the like can be used, and a mixture thereof can also be used. As the pigment, C.I. I. Pigment Red 5,
48: 1, 53: 1, 57: 1, 122, 1
39, 144, 149, 166, 177, 1
78, ibid. 222, C.I. I. Pigment Orange 31, the same 43, C.I. I. Pigment Yellow 14, Same 17 and Same 9
3, 94, 138, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 60 and the like, and a mixture thereof can also be used. The number average primary particle size varies depending on the type, but is generally about 10
About 200 nm is preferable.

The coloring agent may be added by adding the aggregating agent to the polymer particles prepared by the emulsion polymerization method to agglomerate them to color the polymer or polymerizing the monomer. It is possible to use a method in which a coloring agent is added and polymerized to obtain colored particles. When the colorant is added at the stage of preparing the polymer, it is preferable that the surface is treated with a coupling agent or the like so as not to hinder radical polymerizability.

Further, low molecular weight polypropylene (number average molecular weight = 1500 to 9000) or low molecular weight polyethylene as a fixability improving agent may be added.

Similarly, various charge control agents are known,
Moreover, the thing which can be disperse | distributed in water can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines,
Examples thereof include secondary ammonium salt compounds, azo-based metal complexes, salicylic acid metal salts or metal complexes thereof.

The particles of these charge control agents and fixability improvers have a number average primary particle diameter of 10 to 50 in a dispersed state.
It is preferably about 0 nm.

A suspension polymerization method toner in which a toner constituent component such as a colorant or the like is dispersed or dissolved in a so-called polymerizable monomer is suspended in an aqueous medium and then polymerized to obtain a toner is subjected to a polymerization reaction. The shape of the toner particles can be controlled by controlling the flow of the medium in the reaction vessel. That is, when a large number of toner particles having a shape factor of 1.2 or more are formed, the flow of the medium in the reaction vessel is made turbulent, and the polymerization proceeds to exist in the aqueous medium in a suspended state. When the oil droplets gradually become polymerized and become soft particles, the particles collide with each other to promote coalescence of the particles, and particles with an irregular shape are obtained. . When spherical toner particles having a shape factor of less than 1.2 are formed, spherical particles can be obtained by avoiding collision of particles by making the flow of the medium in the reaction vessel a laminar flow. By this method, the distribution of toner shape can be controlled within the range of the present invention.

The reaction device for polymerized toner preferably used in the present invention will be described below. First, a reaction apparatus preferably used for producing a polymerized toner will be described.
2 and 3 are a perspective view and a cross-sectional view showing an example of a polymerized toner reaction device, respectively. In the reactor shown in FIGS. 2 and 3, a rotating shaft 3j is vertically provided at the center of a vertical cylindrical stirring tank 2j having a heat exchange jacket 1j mounted on the outer periphery thereof, and stirring is performed on the rotating shaft 3j. A lower stirring blade 40j arranged near the bottom surface of the tank 2j and a stirring blade 50j arranged further above are provided. The upper-stage stirring blade 50j is arranged at an intersection angle α preceding the lower-stage stirring blade 40j in the rotational direction.
In the case of producing the toner of the present invention, the crossing angle α is 9
It is preferably less than 0 degree (°). The lower limit of the intersection angle α is not particularly limited, but is preferably about 5 ° or more, and more preferably 10 ° or more. When three-stage stirring blades are provided, the intersecting angle α between adjacent stirring blades is preferably less than 90 degrees.

With such a structure, the medium is first agitated by the agitating blades 50j arranged in the upper stage, and a downward flow is formed. Then, the stirring blade 40j arranged in the lower stage accelerates the flow formed by the stirring blade 50j in the upper stage further downward, and the stirring blade 50j
It is presumed that a downward flow is also formed by itself, and the flow accelerates and progresses as a whole. As a result, a basin having a large shear stress formed as a turbulent flow is formed, and it is presumed that the shape of the obtained toner particles can be controlled.

2 and 3, the arrow indicates the direction of rotation, 7j is an upper material charging port, 8j is a lower material charging port, and 9j is a turbulent flow forming member for making stirring effective.

Here, the shape of the stirring blade is not particularly limited, but it has a rectangular plate shape, a blade with a cutout, a central portion with one or more holes, a so-called slit. Things etc. can be used. Specific examples of these are shown in FIG. Stirring blade 5 shown in FIG.
a has no central hole, the stirring blade 5b shown in FIG. 6B has a large central hole 6b in the center, and the stirring blade 5c shown in FIG. 6C has a horizontally long central hole 6c (slit). ), The stirring blade 5d shown in FIG.
There is a (slit). Further, in the case of providing a three-stage stirring blade, even if the middle hole portion formed in the upper stirring blade and the middle hole portion formed in the lower stirring blade are different, they may be the same. It may be.

The gap between the upper and lower stirring blades having the above-mentioned structure is not particularly limited, but it is preferable that there is a gap at least between the stirring blades. The reason for this is not clear, but it is considered that the stirring efficiency is improved because the flow of the medium is formed through the gap. However, the gap has a width of 0.5 to 50%, preferably a width of 1 to 30% with respect to the liquid surface height in a stationary state.

Further, the size of the stirring blade is not particularly limited, but the total height of all the stirring blades is 50% to 100%, preferably 60% to 50% of the liquid surface height in a stationary state. 95
%.

On the other hand, in the case of a polymerized toner in which resin particles are associated or fused with each other in an aqueous medium, the flow and temperature distribution of the medium in the reaction vessel at the fusion stage are controlled to further improve the shape after fusion. By controlling the heating temperature, stirring rotation number, and time in the control step, the shape distribution and shape of the entire toner can be arbitrarily changed.

That is, in the case of a polymerization method toner in which resin particles are associated or fused, the flow in the reaction device is a laminar flow,
By using a stirring blade and a stirring tank that can make the internal temperature distribution uniform, by controlling the temperature, rotation speed, and time in the fusion process and shape control process, the desired shape factor and uniform A toner having a shape distribution can be formed. The reason for this is that when fusion is performed in a laminar flow-forming place, strong stress is not applied to particles (association or agglomerated particles) in which aggregation and fusion are progressing, and in a laminar flow in which the flow is accelerated, It is presumed that, as a result of the uniform temperature distribution in the stirring tank, the shape distribution of the fused particles becomes uniform. Furthermore, heating in the subsequent shape control process,
By stirring, the fused particles gradually become spherical and the shape of the toner particles can be arbitrarily controlled.

As the stirring tank used in the production of the polymerization method toner in which the resin particles are associated or fused, the same one as in the suspension polymerization method can be used. In this case, it is necessary not to provide an obstacle such as a baffle plate that forms a turbulent flow in the stirring tank.

The shape of this stirring blade is not particularly limited as long as it forms a laminar flow and does not form a turbulent flow. However, it may have a continuous surface such as a rectangular plate shown in FIG. 4 (c). What is formed is preferable, and may have a curved surface.

Further, in the toner used in the present invention, it is possible to exert more effects by adding fine particles such as inorganic fine particles and organic fine particles as an external additive.
The reason for this is presumed to be that the embedding and detachment of the external additive can be effectively suppressed, and the effect is remarkable.

As the inorganic fine particles, it is preferable to use inorganic oxide particles such as silica, titania and alumina, and these inorganic fine particles are subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent or the like. preferable. The degree of hydrophobic treatment is not particularly limited, but methanol wettability of 40 to 95 is preferable. Methanol wettability is an evaluation of wettability with respect to methanol. In this method, 50 ml of distilled water placed in a beaker with an internal volume of 200 ml was charged with inorganic fine particles to be measured in an amount of 0.
Weigh 2 g and add. Methanol is dripped slowly from a buret whose tip is dipped in the liquid, with slow stirring until the whole inorganic fine particles become wet. When the amount of methanol required to completely wet the inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the following formula.

Hydrophobicity = (a / (a + 50)) × 100 The addition amount of this external additive is 0.1 to 5% in the toner.
It is 0% by mass, preferably 0.5 to 4.0% by mass. Further, various external additives may be used in combination.

A fatty acid metal salt may be added as an external additive to the toner used in the present invention. Fatty acids and metal salts thereof include undecyl acid, lauric acid, tridecyl acid, dodecyl acid, myristic acid, palmitic acid, pentadecyl acid, stearic acid, heptadecyl acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid, etc. And long-chain fatty acids thereof, and examples of the metal salt thereof include salts with metals such as zinc, iron, magnesium, aluminum, calcium, sodium and lithium. In the present invention, zinc stearate is particularly preferable. << Developer >> The toner used in the present invention may be a one-component developer or a two-component developer, but is preferably a two-component developer.

When used as a one-component developer, there is a method in which the above toner is used as it is as a non-magnetic one-component developer. Usually, however, magnetic particles of about 0.1 to 5 μm are contained in the toner particles. Used as a developer. As a method of containing it, it is common to incorporate it in the non-spherical particles in the same manner as the colorant.

Further, it can be used as a two-component developer by mixing with a carrier. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, alloys of these metals with metals such as aluminum and lead are used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The volume average particle diameter of the magnetic particles is 15
˜100 μm, more preferably 25 to 60 μm.

The volume average particle diameter of the carrier is typically measured by a laser diffraction type particle size distribution measuring apparatus "HELOS" equipped with a wet disperser (SYMPATIC (SYMP).
(Made by ATEC)).

The carrier is preferably one in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, but for example, an olefin resin, a styrene resin, a styrene / acrylic resin, a silicone resin, an ester resin, a fluorine-containing polymer resin, or the like is used. The resin for forming the resin-dispersed carrier is not particularly limited, and known ones can be used, and for example, styrene acrylic resin, polyester resin, fluorine resin, phenol resin, etc. can be used. it can.

The two-component developer is prepared by mixing the toner and the carrier. The toner is mixed in a toner concentration of 2 to 10% by mass based on the developer.

The developing method according to the present invention is not particularly limited. Even in the contact development method in which development is performed in a state where the surface of the photoconductor and the developer layer are in contact with each other in the development area, the photoconductor and the developer layer are kept in the non-contact state in the development area, and an alternating electric field, etc. A non-contact developing method in which toner is caused to fly in the gap between the surface of the photoconductor and the developer layer by the action to develop the toner may be used.

Next, an image forming method using the contact charging method of the present invention will be described. << Charging Step >> As the charging member of the present invention, various charging members such as a magnetic brush type, a charging roller type, and a blade type can be used. Among them, the charging roller type or the magnetic brush type is the most preferable as the charging member. Used in invention. That is, a charging roller or a magnetic brush, which can easily obtain uniform charging, is preferable. The charging roller type charging means and the magnetic brush type charging means will be described below.

In the present invention, the charging roller composed of the conductive elastic member is brought into contact with the photosensitive member (image carrier), and a voltage is applied to the charging roller to apply the photosensitive member (image carrier).
Can be charged.

Such a charging roller system may be either a DC charging system for applying a DC voltage to the roller or an induction charging system for applying an AC voltage to the roller.

The frequency f of the voltage applied by the induction charging method may be any frequency. However, in order to prevent strobing, that is, stripes, it depends on the relative speed of the conductive elastic roller and the image carrier member. A suitable frequency can be selected. The relative speed can be determined by the size of the contact area between the conductive elastic roller and the image carrier.

The conductive elastic roller is formed by coating the outer periphery of a core metal with a layer made of a conductive elastic member (simply referred to as a conductive elastic layer or H, a conductive rubber layer).

The rubber composition that can be used for the conductive rubber layer includes polynorbornene rubber and ethylene-
Examples thereof include propylene rubber, chloroprene rubber, acrylonitrile rubber, silicone rubber and the like. These rubbers can be used alone or as a mixed rubber of two or more kinds.

In order to impart conductivity, these rubber compositions are blended with a conductivity-imparting agent and used. Examples of suitable conductivity-imparting agents include publicly known carbon black (furnace-based carbon black or ketjen black) and metal powder such as tin oxide. The conductivity-imparting agent is used in an amount of about 5 to about 50 parts by mass based on the total amount of the rubber composition.

In addition to the rubber base material, the foaming agent, and the conductivity-imparting agent, the rubber composition may be blended with a chemical agent for rubber and a rubber additive, if necessary, to give a conductive foamed rubber composition.
Chemicals for rubber, as rubber additives, vulcanizing agents such as sulfur and peroxide, vulcanization accelerators such as zinc white, stearic acid, sulfenamide-based, thirium-based, thiazole-based,
It is possible to use vulcanization accelerators such as granidine-based, amine-based, phenol-based, sulfur-based and phosphorus-based antioxidants, or antioxidants, ultraviolet absorbers, ozone deterioration inhibitors, tackifiers, etc. Further, various reinforcing agents, friction coefficient adjusting agents, and inorganic fillers such as silica, talc, and clay may be arbitrarily selected and used. These conductive rubber layers are 10 ³ to 1
It preferably has a direct current volume resistivity in the range of 0 ⁷ Ωcm.

Further, a releasable coating layer may be provided outside these conductive elastic layers for the purpose of preventing the toner remaining on the surface of the photoconductor from adhering to the charging member. The coating layer also prevents the oil from seeping out from the elastic layer, cancels the resistance unevenness of the elastic layer, makes the resistance uniform, protects the surface of the charging roller, and adjusts the hardness of the charging roller. Etc. The coating layer may be any layer as long as it satisfies the above physical properties, and may be a single layer or a plurality of layers. Materials include hydrin rubber, urethane rubber, nylon, polyvinylidene fluoride,
Examples thereof include resins such as polyvinylidene chloride. The thickness of the coating layer is preferably 100 to 1000 μm, and the resistance value is preferably 10 ⁵ to 10 ⁹ Ω · cm. In addition, it is preferable that the resistance value increases as it approaches the surface layer. As a method of adjusting the resistance, it is possible to include a conductive material such as carbon black, metal and metal oxide in the coating layer.

In order to adjust the surface roughness Rz of the charging roller of the present invention, it is preferable that the surface layer (conductive elastic layer or coating layer) of the charging roller contains powder. The particles used in the present invention may be either an inorganic substance or an organic substance, but in the case of the inorganic substance, silica powder is particularly preferable. Examples of organic substances include urethane resin particles, nylon particles, silicone rubber particles, and epoxy resin particles.
These particles may be used alone or in admixture of two or more. Suitable particles have a surface layer surface roughness Rz of 0.05 to 1
A substance that can be adjusted to the range of 0.0 μm may be selected, but if the particle size of the particles is in the range of 1 to 20 μm, the desired surface roughness range can be easily achieved. If the particle size exceeds 20 μm,
The surface roughness Rz also exceeds 10.0 μm, and does not serve the intended purpose. Conversely, if the particle size is less than 1 μm, the surface roughness R
z tends to be less than 0.05 μm, and this also fails the intended purpose.

The reason why the surface roughness Rz is set in the range of 0.05 to 10.0 μm is that when it exceeds 10.0 μm, the toner filming on the roller surface becomes remarkable, and it is less than 0.05 μm. This is because the adhesion between the charging roller and the photosensitive drum is increased, that is, the contact area is increased, so that the charging noise cannot be suppressed.

The blending ratio of the powder in the surface layer was 100% of resin.
It is preferable to mix and disperse in a ratio of about 5 to about 20 parts by mass with respect to parts by mass.

The charging roller of the present invention can be manufactured, for example, as follows. That is, first, a metal rotary shaft (core metal) is placed in a molding die having a cylindrical molding space, the conductive elastic layer forming material is filled in the molding die, and vulcanization is performed to form the outer circumference of the rotation shaft. A conductive elastic layer is formed on the surface. Then, the rotary shaft on which the conductive elastic layer is formed is taken out from the mold. On the other hand, a material such as urethane resin is mixed with granules, a conductivity imparting agent and other additives, and the mixture is mixed and stirred using a ball mill or the like to prepare a surface layer forming material mixture. Then, this mixture is applied by a dip method, a roll coating method, a spray coating method or the like on the surface of the rotating shaft on which the conductive elastic layer is formed, dried, and cured by heating to form a two-layer structure. A charging roller can be manufactured.

The charging roller thus obtained has a surface roughness Rz of 0.05 to 1 in the surface layer which is the outermost layer.
It is formed to 0.0 μm.

Next, the image forming apparatus of the present invention will be described. FIG. 5 is a diagram illustrating an example of an image forming apparatus that performs roller charging. This image forming apparatus is for carrying out the present invention, and a charging roller is brought into contact with a photosensitive drum to charge a charging electrode for forming an electrostatic latent image (charging step),
Further, a transfer roller is used as a transfer pole for transferring the toner to the transfer paper (transfer process). This transfer roller is in contact with the photoconductor drum either directly or with a transfer paper sandwiched between the transfer roller and the so-called contact charging method, and the electrostatic latent image is formed by non-contact development. It is to develop.

In FIG. 5A, an electrostatic latent image is formed on the photosensitive drum 2 charged by the charging roller 1 (image exposing step). Then, this electrostatic latent image is developed into a toner image by the developing sleeve 4 which is the developer carrying member of the developing device 3 arranged in the vicinity of the photosensitive drum 2 (developing step). Then, after the charge of the photoconductor drum 2 is removed by the charge eliminating lamp 5 before transfer, the toner image has a polarity opposite to that of the toner by the transfer roller 6 on the transfer sheet P conveyed by the conveying roller 8 from the sheet feeding cassette. Is applied, and the toner is transferred to the transfer paper P by the electrostatic force of the charges of the opposite polarity. The transfer paper P after the toner transfer is separated from the photoconductor drum 2 and then sent to the fixing device by the conveyor belt 7, and the toner image is fixed on the transfer paper P by the heating roller and the pressing roller (fixing step).

A bias voltage composed of DC and AC components is applied from the power source 9 (10) to the charging roller 1 (and the transfer roller 6), and the charging and charging of the photosensitive drum 2 is performed in a state where the ozone generation amount is extremely small. The toner image is transferred to the transfer paper P. The bias voltage is usually ± 500 to 10
DC bias of 00V and 100Hz-1 superimposed on this
It consists of AC bias of 0 to 3500 V (pp) at 0 KHz.

The charging roller 1 and the transfer roller 6 are driven or forcedly rotated while being pressed against the photosensitive drum 2.

The pressure contact with the photosensitive drum 2 is 10 to 10
The rotation of the roller is set to 0 g / cm and is set to 1 to 8 times the peripheral speed of the photosensitive drum 2.

As shown in FIG. 5B, the charging roller 1
(And the transfer roller 6) is composed of a cored bar 20 and a rubber layer such as chloroprene rubber, urethane rubber, silicone rubber or the like, which is a conductive elastic member provided on the outer periphery thereof, or a sponge layer 21 thereof, preferably the outermost layer. 0.01 to 1 μm
The protective layer 22 is made of a thick releasable fluorine resin or silicone resin layer.

After the transfer, the photosensitive drum 2 is cleaned by pressure contact with the cleaning blade 12 of the cleaning device 11 and is ready for the next image formation.

The electrophotographic image forming apparatus is constructed by integrally combining a photosensitive member and components such as a developing unit and a cleaning unit as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Is also good. Further, at least one of an image exposing device, a developing device, a transfer or separating device, and a cleaning device is integrally supported together with a photoconductor to form a process cartridge, which is a detachable single unit in the device main body, such as a rail of the device main body. The guide means may be used to make it detachable.

In FIG. 5, a roller charger is used for both the charging device and the transfer pole. However, in the present invention, the essential constituent requirement of the present invention is that a charging roller is used for the charging device. A transfer means other than the transfer roller may be used for the transfer pole.

Next, the magnetic particles forming the magnetic brush for charging will be described. 6 is a diagram of a contact type magnetic brush charging device, and FIG. 7 is a diagram showing a relationship between an AC bias voltage and a charging potential by the charging device of FIG.

Generally, when the volume average particle diameter of the magnetic particles forming the charging magnetic brush is large, the state of the ears of the magnetic brush formed on the charging magnetic particle carrier (carrier) is rough, and therefore the electric field is generated by the electric field. Even when charged while vibrating, unevenness is likely to appear on the magnetic brush, which causes a problem of uneven charging.
In order to solve this problem, the volume average particle diameter of the magnetic particles should be reduced. As a result of the experiment, the volume average particle diameter is 200 μm.
When the thickness is m or less, the effect begins to appear, and particularly when it is 150 μm or less, the problem associated with the coarseness of the ears of the magnetic brush does not substantially occur. However, if the particles are too fine, they tend to adhere to the surface of the photoconductor drum 50 at the time of charging, or are easily scattered. These phenomena are also related to the strength of the magnetic field acting on the particles and the strength of the magnetization of the particles due to the strength of the magnetic fields, but generally, the volume average particle diameter of the particles becomes prominent at 20 μm or less.

From the above, the volume average particle diameter of the magnetic particles is 200 μm or less and 20 μm or more, and 30 magnetic particles having a particle diameter of ½ times or less of the number average particle diameter of the magnetic particles are used. It is necessary to be less than or equal to%. It is preferable that the magnetization intensity is 30 to 100 emu / g.

Such a magnetic particle is a metal such as iron, chromium, nickel, cobalt or the like, or a compound or alloy thereof, similar to those in the magnetic carrier particles of the conventional two-component developer described above as a magnetic substance, for example, four. Iron trioxide, γ-
The surface of ferromagnetic particles such as ferric oxide, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy, or the surface of these magnetic particles is styrene resin, vinyl resin, ethylene resin, rosin modified Particles obtained by coating with a resin such as a resin, an acrylic resin, a polyamide resin, an epoxy resin, a polyester resin, or by making a resin containing magnetic fine particles dispersed therein have a conventionally known average particle diameter. It is obtained by selecting the particle size with a selecting means.

The spherical shape of the magnetic particles is
The particle layer formed on the carrier is made uniform, and a high bias voltage can be uniformly applied to the carrier. That is, the fact that the magnetic particles are spherical means that (1) generally, the magnetic particles are easily magnetized and adsorbed in the long-axis direction, but due to the spherical shape, the directionality is lost, so that the magnetic particle layer is uniformly formed. , (2) To prevent the occurrence of locally low resistance regions and unevenness of layer thickness. (2) With the increase in the resistance of magnetic particles, the edge part as seen in conventional particles is eliminated, and the electric field to the edge part is eliminated. Concentration does not occur, and as a result, even if a high bias voltage is applied to the carrier for carrying the magnetic particles for charging, it is possible to uniformly discharge the surface of the photosensitive drum 50 and prevent uneven charging.

As the spherical particles having the above effects, conductive particles are preferably formed so that the magnetic particles have a resistivity of 10 ⁵ to 10 ¹⁰ Ωcm. The resistivity is 1 kg / cm on the packed particles after the particles are placed in a container having a cross-sectional area of 0.50 cm ² and tapped.
^Apply a load of ² , and apply 1000V / between the load and the bottom electrode.
It is a value obtained by reading the current value when a voltage that causes an electric field of cm is applied. When this resistivity is low, when a bias voltage is applied to the carrier, electric charges are injected into the magnetic particles, Magnetic particles are likely to adhere to the surface of the photosensitive drum 50, or dielectric breakdown of the photosensitive drum 50 due to a bias voltage is likely to occur. Also,
If the resistivity is high, charge injection is not performed and charging is not performed.

Further, the contact type magnetic brush charging device 12
It is desirable that the magnetic particles used for No. 0 have a small specific gravity and have a suitable maximum magnetization so that the magnetic brush constituted by the particles moves lightly by an oscillating electric field and does not cause external scattering. Specifically, those having a true specific gravity of 6 or less and a maximum magnetization of 30 to 100 emu / g, particularly 40 to 8
It has been found that good results are obtained with 0 emu / g.

In summary, the magnetic particles are spherical so that at least the ratio of the major axis to the minor axis is 3 times or less, there are no protrusions such as needles and edges, and the resistivity is Preferably, it is desired to be in the range of 10 ⁵ to 10 ¹⁰ Ωcm. Then, such spherical magnetic particles should be selected as spherical as possible for the magnetic particles, and in the particles of the magnetic material fine particle dispersion system, the fine particles of the magnetic material should be used as much as possible, and the spheroidizing treatment should be performed after the formation of the dispersed resin particles. It is manufactured by applying or by forming dispersed resin particles by a spray drying method.

According to FIG. 6 or FIG. 7, the magnetic brush charging device 120 as the charging device has the rotating photosensitive drum 50.
Of a cylindrical shape using, for example, an aluminum material or a stainless material as a charging magnetic particle carrier that is opposed to the photosensitive drum 50 and is rotated in the same direction (counterclockwise direction) at a portion (charging portion T) close to the photosensitive drum 50 Magnet body 1 including charging sleeve 120a and N and S poles provided inside the charging sleeve 120a.
21, a magnetic brush composed of magnetic particles formed on the outer peripheral surface of the charging sleeve 120a by the magnet body 121 to charge the photosensitive drum 50, and a magnetic brush on the charging sleeve 120a at the NN magnetic pole portion of the magnet body 121. A scraper 123 for scraping the brush, an agitating screw 124 for agitating the magnetic particles in the magnetic brush charging device 120, or agitating the magnetic particles in the magnetic brush charging device 120 by discharging the used magnetic particles by overflowing them from the outlet 125 of the magnetic brush charging device 120. It is configured by the brush spike control plate 126. The charging sleeve 120a is rotatable with respect to the magnet body 121,
It is preferable to rotate at a peripheral speed of 0.1 to 1.0 times in the same direction (counterclockwise direction) as the moving direction of the photoconductor drum 50 at a position facing the photoconductor drum 50. A conductive carrier that can apply a charging bias voltage is used as the charging sleeve 120a, and in particular, a magnet body 121 having a plurality of magnetic poles inside the conductive charging sleeve 120a having a particle layer formed on the surface thereof. Those having a structure provided with are preferably used. In such a carrier, the magnetic particle layer formed on the surface of the electrically conductive charging sleeve 120a moves in a wavy manner due to the relative rotation with the magnet body 121, so that new magnetic particles are moved. Is supplied one after another, and even if the magnetic particle layer on the surface of the charging sleeve 120a has some non-uniformity in the layer thickness, its effect is sufficiently covered so as not to cause a practical problem due to the corrugation. It is preferable that the surface of the charging sleeve 120a has an average roughness of 5.0 to 30 μm for stable and uniform transfer of magnetic particles. If the surface is smooth, the transfer cannot be performed sufficiently, and if it is too rough, the surface is convex. Overcurrent flows from the part, and uneven charging is likely to occur in either case. Sandblasting is preferably used to achieve the above surface roughness. Further, the outer diameter of the charging sleeve 120a is preferably 5.0 to 20 mm. This ensures the contact area required for charging. If the contact area is larger than necessary, the charging current will be too large,
If it is small, uneven charging tends to occur. Further, when the diameter is small as described above, the magnetic particles are easily scattered or adhered to the photosensitive drum 50 due to the centrifugal force.
The linear velocity of is almost the same as the moving velocity of the photosensitive drum 50,
It is preferably slower than that.

Further, the thickness of the magnetic particle layer formed on the charging sleeve 120a is preferably such that it is sufficiently scraped off by the regulating means to form a uniform layer. If the amount of magnetic particles on the surface of the charging sleeve 120a is too large in the charging region, the magnetic particles are not sufficiently vibrated to cause abrasion of the photoconductor and uneven charging, and an overcurrent tends to flow, resulting in a driving torque of the charging sleeve 120a. Has the drawback of becoming large. On the contrary, if the amount of the magnetic particles present on the charging sleeve 120a in the charging area is too small, an incomplete portion may be formed in contact with the photosensitive drum 50, and the magnetic particles may adhere to the photosensitive drum 50 or cause uneven charging. become. As a result of repeated experiments, it has been found that the preferable adhesion amount of the magnetic particles in the charged region is 100 to 400 mg / cm ² , and particularly preferably 200 to 300 mg / cm ² . The amount of adhesion is an average value in the charged area of the magnetic brush.

Magnetic Brush Charging Device 12 as Charging Device
0 is a charging bias in which an alternating current (AC) bias AC3 is superimposed on the direct current (DC) bias E3 if necessary, for example, −100 to −500 V of the same polarity (negative polarity in this embodiment) as the toner as the direct current bias E3.
However, the frequency of AC bias AC3 is 1 to 5 kHz.
The peripheral surface of the photosensitive drum 50 is contacted and rubbed by the charging sleeve 120a to which a charging bias of z and a voltage of 300 to 500 V _PP is applied, and the photosensitive drum 50 is charged. Since an oscillating electric field is formed between the charging sleeve 120a and the photoconductor drum 50 by applying the voltage of the AC bias AC3, the photoconductor layer 10a passes through the magnetic brush.
The charge is smoothly injected to the top, and the charging is uniformly performed at high speed.

The magnetic brush on the charging sleeve 120a that has charged the photosensitive drum 50 is dropped from the charging sleeve 120a by the scraper 123 on the NN magnetic pole portion provided on the magnet body 121, and in the vicinity of the charging sleeve 120a. After being stirred by the stirring screw 124 that rotates in the opposite direction (counterclockwise) to the charging sleeve 120a, the magnetic brush is formed again and it is conveyed to the charging unit T.

As shown in FIG. 7, the relationship between the peak-to-peak voltage (V _PP ) of the AC bias AC3 of the charging bias and the charging potential is that the charging potential becomes larger as the peak-to-peak voltage V _PP becomes larger. The potential is V1 with a constant peak-peak voltage, and the DC bias E3 of the charging bias.
Has a characteristic that it saturates at a value almost equal to the value VS of, and the charging potential hardly changes even if the peak-to-peak voltage V _PP is further increased. Although the electric resistance of the magnetic particles varies depending on the environmental conditions, the electric resistance increases as the toner is fused to the surface of the magnetic particles as it is used. Therefore, the characteristic curve is shown on the left side as shown by a solid line in the case of new magnetic particles in the initial stage of use, and on the right side as shown by a dotted line in the case of magnetic particles used for a long time as shown in (b). Will be located in.

In the contact type charging device of the image forming apparatus of the present invention, the voltage value of the DC bias E3 corresponding to the charging potential is set to a predetermined value when the mounting power source is turned on or before the printing is started, and the peak / peak of the AC bias AC3. Voltage (V
A charging bias in which _PP ) is gradually increased from a low value is applied, and the charging potential of the photosensitive drum 50 which changes at that time is detected by the electrometer ES. The detected charging potential is A /
After being converted into a digital value by the D converter, it is input to the control unit (CPU). In the control unit, the value of V _PP when the charging potential reaches the saturation point of the predetermined value VS is defined as the proper bias value V1 and the printing operation is performed.

That is, when printing is performed, the AC bias AC3 is gradually increased (swept) from a low value.
The value V1 of V _PP of the AC bias AC3 is obtained, and the bias signal is output from the control unit. This control signal is converted into an analog value by the D / A converter, and then the AC bias A
The AC bias AC3 is sent to C3 and outputs the determined peak-to-peak voltage V1. The peak-peak voltage V1 at that time and the specified value V2 to be exchanged due to the deterioration of the magnetic particles stored in the memory are read out and compared with this.
Since the resistance of the magnetic particles increases due to the mixing of toner, the proper bias value V1 increases with the use of printing. Along with this, the applied V _PP increases and a non-chargeable state occurs. While the image formation is continued while the measured voltage value is smaller than the specified value V2 indicating that charging is impossible, when the measured voltage value is larger than the specified value V2, the image forming operation stop signal is sent from the control unit to stop the image forming operation, and not shown. The abnormality of the charging device is displayed on the display of the operation unit. Based on this display, the supply bottle 220 of the magnetic particles for charging is set in the magnetic brush charging device 120, and an opening / closing lid (not shown) on the bottom of the supply bottle 220 is opened to drop and supply the magnetic particles to the magnetic brush charging device 120. To do. Although the electrometer ES was used to measure the potential of the photosensitive drum 50 in the above, the AC bias V _PP is changed by connecting the bias power source to the DC ammeter, and V when the current value reaches the saturation point is obtained. _It is also possible to set _PP to an appropriate bias value V1, compare it with a prescribed value V2, and supply magnetic particles when V1 is exceeded.

Also, during maintenance or at regular intervals such as 50,000 prints, the magnetic particles for charging are exchanged. A replacement signal is output through the control unit at regular intervals of every maintenance print stored in the memory or, for example, every 50,000 prints, and the supply of the supply bottle 220 of the magnetic particles for charging preset by the drive of the drive motor (not shown). The roller 221 is rotated, and all the magnetic particles in the supply bottle 220 are dropped into the magnetic brush charging device 120 at one time. It is also possible to remove the empty supply bottle 220 after the supply and set a new supply bottle 220 to control the image forming apparatus to the operating state. Further, at a regular time, the control unit displays a supply signal such as a blinking lamp on an operation unit (not shown), sets the supply bottle 220 on the magnetic brush charging device 120, and opens an opening / closing lid (not shown) on the bottom of the supply bottle 220. Alternatively, the magnetic particles may be supplied.

The dropped magnetic particles are conveyed by the rotating charging sleeve 120a, scraped off from the surface of the charging sleeve 120a by the scraper 123 and supplied to the bottom of the magnetic brush charging device 120. Along with this, the used magnetic particles stored in the magnetic brush charging device 120 are overflowed from the discharge port 125 by the stirring screw 124 rotated counterclockwise, and the common magnetic particle recovery container 300 is passed through the duct DB. Will be collected. At this time, the amount of magnetic particles supplied from the supply bottle 220 into the magnetic brush charging device 120 once is 20 to 5 with respect to all the magnetic particles stored in the magnetic brush charging device 120.
0 mass% is preferable. If the amount is less than 20% by mass, the amount of newly supplied magnetic particles is too small to have an exchange effect and good charging cannot be performed. If the amount exceeds 50% by mass, new magnetic particles overflow.

As described above, good charging performance is maintained for a long time without deteriorating the magnetic particles in the charging device.

FIG. 8 is a sectional view showing an example of an image forming apparatus having the magnetic brush charger of the present invention. In FIG. 8, reference numeral 50 denotes a photosensitive drum (photosensitive member) which is an image bearing member, and is a photosensitive member in which an organic photosensitive layer is applied on the drum and the resin layer of the present invention is applied thereon, and is grounded in a clockwise direction. Is driven to rotate. Reference numeral 52 denotes a magnetic brush charger, which can uniformly charge the peripheral surface of the photosensitive drum 50 (charging step). Prior to the charging by the charger 52, the exposure unit 5 using a light emitting diode or the like in order to eliminate the history of the photosensitive member in the previous image formation.
Alternatively, the peripheral surface of the photoconductor may be erased by performing the exposure with 1.

After uniformly charging the photosensitive member, the image exposing device 53 performs image exposure based on the image signal (image exposing step). The image exposure device 53 in this figure uses a laser diode (not shown) as an exposure light source. Rotating polygon mirror 53
1, the light whose optical path is bent by the reflection mirror 532 through the f.theta. Lens, etc., scans the photosensitive drum to form an electrostatic latent image.

The electrostatic latent image is then developed by the developing device 54 (developing step). A developing device 54 containing a developer composed of toner and carrier is provided on the periphery of the photosensitive drum 50, and development is performed by a developing sleeve 541 that contains a magnet and holds the developer and rotates. The developer is, for example, a carrier in which an insulating resin is coated around the above-mentioned ferrite core, a coloring agent such as carbon black mainly containing the above-mentioned styrene acrylic resin, a charge control agent, and the low molecular weight polyolefin of the present invention. The toner is obtained by externally adding silica, titanium oxide or the like to the colored particles made of, and the developer is 100 to 6 on the developing sleeve 541 by a layer forming means (not shown).
The layer is regulated to have a layer thickness of 00 μm, and is conveyed to the developing area for development. At this time, normally, a DC bias is applied between the photosensitive drum 50 and the developing sleeve 541, and if necessary, an AC bias voltage is applied to develop. Further, the developer is developed in a state of being in contact with or non-contacting with the photoreceptor.

The transfer material (also referred to as recording paper) P is fed by the paper feed roller 57 when the transfer timing is adjusted after image formation.
The paper is fed to the transfer area by the rotation operation of.

In the transfer area, a transfer roller (transfer device) is provided on the peripheral surface of the photosensitive drum 50 in synchronization with the transfer timing.
The transfer material P is pressed into contact with the sheet, and the transferred transfer material P is sandwiched and transferred (transfer step).

Next, the transfer material P is destaticized by a separating brush (separator) 59 which is brought into pressure contact with the transfer roller almost at the same time, is separated by the peripheral surface of the photosensitive drum 50 and is conveyed to the fixing device 60, and is heated by the heat roller. After the toner is fused by heating and pressurizing the pressure roller 601 and the pressure roller 602 (fixing step), the toner is discharged to the outside of the apparatus via the discharge roller 61. Incidentally, the transfer roller 58 and the separating brush 5 described above.
After the transfer material P has passed through, 9 is retracted and separated from the peripheral surface of the photosensitive drum 50 to prepare for the next toner image formation.

On the other hand, the photosensitive drum 50 after the transfer material P is separated is the cleaning blade 6 of the cleaning device 62.
Residual toner is removed and cleaned by pressing 21 to receive the charge removal by the exposure unit 51 and the charging by the charger 52 again, and the next image forming process starts.

Reference numeral 70 denotes a detachable process cartridge in which a photoconductor, a charging device, a transfer device / separator, and a cleaning device are integrated.

As the image forming apparatus, the above-mentioned photoreceptor is used.
The components such as the developing device and the cleaning device may be integrally combined as a process cartridge, and this unit may be detachably attached to the apparatus main body. Further, at least one of a charging device, an image exposing device, a developing device, a transfer or separating device, and a cleaning device is integrally supported with a photosensitive member to form a process cartridge, which is a detachable single unit in the apparatus main body. It may be detachable by using a guide means such as a rail of the apparatus body.

In the image exposure, when the image forming apparatus is used as a copying machine or a printer, the photoconductor is irradiated with reflected light or transmitted light from the original, or the original is read by a sensor and converted into a signal. This is performed by irradiating the photoconductor with light by scanning the laser beam, driving the LED array, or driving the liquid crystal shutter array.

When used as a printer for a facsimile, the image exposure device 13 performs exposure for printing the received data.

The image forming apparatus of the present invention can be applied to general electrophotographic apparatuses such as copying machines, laser printers, LED printers and liquid crystal shutter printers. It can be widely applied to devices such as light printing, plate making, and facsimile.

[0239]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto. In addition, "part" in a sentence represents a "mass part."

The intermediate layer dispersions of Examples and Comparative Examples were prepared as follows. Preparation of intermediate layer dispersion liquid 1 Polyamide resin CM8000 (manufactured by Toray) 1 part Titanium oxide SMT500SAS (manufactured by Teika; surface treatment is silica treatment, alumina treatment, and methylhydrogenpolysiloxane treatment) 3 parts Methanol 10 parts sand mill The dispersion time was 10 hours with a disperser and the dispersion was carried out in a batch manner to prepare an intermediate layer dispersion liquid 1.

Preparation of Intermediate Layer Dispersions 2 to 7 Intermediate Layer Dispersions 2 to 2 were prepared in the same manner as Intermediate Layer Dispersion 1 except that titanium oxide and its surface treatment, particle size and solvent were changed as shown in Table 2. 7 was produced.

Preparation of Intermediate Layer Dispersion Liquid 8 (Comparative Example) 1 part of polyamide resin CM8000 (manufactured by Toray Industries, Inc.) was added to and dissolved in a mixed solvent of 7 parts of methanol and 3 parts of 1-propanol to obtain intermediate layer dispersion liquid 8. It was made.

Preparation of Intermediate Layer Dispersion Liquid 9 (Comparative Example) Instead of titanium oxide particles, silica particles (Aerosil R8) were used.
05, Tegusa Co .: not N-type semiconducting particles) was prepared in the same manner as Intermediate Layer Dispersion Liquid 1 to prepare Intermediate Layer Dispersion Liquid 9.

Preparation of Photoreceptor 1 The following intermediate layer coating liquid 1 was prepared and aluminum was vapor-deposited to a thickness of 1.
It was coated on a belt support of polyethylene terephthalate having a thickness of 00 μm to form an intermediate layer 1 having a dry film thickness of 2 μm. In the present invention, the drying condition is low temperature drying and is controlled slowly so that Benard cells are easily generated stably. Drying conditions are 60 ℃,
After 10 minutes, it was dried at 40 ° C. for 30 minutes.

The volume resistivity of the intermediate layer after drying was 2 × 10 ¹⁰ Ω · cm under the above measurement conditions. <Intermediate layer (UCL) coating liquid 1> The intermediate layer dispersion liquid 1 was diluted 2-fold with the same mixed solvent, and allowed to stand overnight and then filtered (filter; Rigimesh filter manufactured by Nippon Pall Ltd. nominal filtration accuracy: 5 μm, pressure). 5 × 10 ⁴ Pa).

The following coating solutions were mixed and dispersed using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied to form a charge generation layer having a dry film thickness of 0.3 μm on the intermediate layer.

<Charge Generating Layer (CGL) Coating Solution> Y-type oxytitanyl phthalocyanine (Cu-Kα characteristic X-rays has a maximum peak angle of 2θ of 27.3 at 27.3) 20 g Polyvinyl butyral (# 6000-C, electric Chemical Industry Co., Ltd.) 10 g t-butyl acetate 700 g 4-methoxy-4-methyl-2-pentanone 300 g The following coating solutions were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied on the charge generation layer to form a charge transport layer having a dry film thickness of 24 μm, and the photoconductor 1 was produced.

<Charge Transport Layer (CTL) Coating Liquid> Charge Transport Agent (4- (2,2-diphenylvinyl) phenyl-di-p-trilylamine) 75 g Polycarbonate Resin (Upilon Z300: Mitsubishi Gas Chemical Co., Inc.) 100 g Chloride Methylene 750 g Preparation of Photoreceptors 2-9 Intermediate Layer Dispersion 1 of Intermediate Layer Coating Solution 1
Except that the intermediate layer coating solutions 2 to 9 were prepared, and the intermediate layer coating solutions 2 to 9 were used in place of the intermediate layer coating solution 1. ~ 9 were produced. The drying conditions are the same as the manufacturing conditions of the photoconductor 1.

Preparation of Photoreceptor 10 A photoreceptor 10 having an intermediate layer 10 was prepared in the same manner as the photoreceptor 1 except that an anodized sealing aluminum substrate was used as the cylindrical aluminum substrate. The drying conditions are the same as the manufacturing conditions of the photoconductor 1.

The volume resistance of these intermediate layers 2 to 10 was 0.5 × 10 ^{10 to} 6 × 10 ¹⁰ Ω · cm under the above measurement conditions.

The contents of each intermediate layer are shown in Table 1 including the evaluation of occurrence of Benard cells.

Evaluation 1 (Evaluation of Intermediate Layer) Further, the surface of the intermediate layer was observed with a scanning electron microscope at a magnification of 200, and a concave portion having a shape as shown in FIG. It was confirmed that they were formed on the front, back, left and right (Benard cell structure), and the following judgment was made. 9A shows a hexagonal concave portion, and b shows a spot-shaped concave portion.

⊚: Polygonal recesses with the longest length of 20 to 200 μm are formed in 50% or more of the intermediate layer surface layer. ○: Polygonal recesses with the longest length of 20 to 200 μm are 10 to 10 of the intermediate layer surface layer. 49% generation ×: Polygonal recesses with a maximum length of 20 to 200 μm were less than 10% of the intermediate surface layer XX: Polygonal recesses with a maximum length of 20 to 200 μm were generated on the intermediate surface layer at all The evaluation results are shown in Table 1.

[0254]

[Table 1]

In Table 1, those listed in the primary treatment column are substances deposited on the surface of titanium oxide particles after the primary treatment,
The items described in the secondary treatment column indicate the substances used in the secondary treatment.

Preparation of Toners 1-1 to 1-5 (Example of Emulsion Polymerization Association Method) 0.90 kg of sodium n-dodecylsulfate and 10.0 L of pure water are put and dissolved with stirring. To this solution, Regal 330R (carbon black manufactured by Cabot) 1.
After 20 kg was gradually added and well stirred for 1 hour, continuous dispersion was carried out for 20 hours using a sand grinder (medium type disperser). This is designated as "colorant dispersion liquid 1". In addition, sodium dodecylbenzene sulfonate 0.055
A solution consisting of kg and 4.0 L of ion-exchanged water is referred to as “anionic surfactant solution A”.

0.014 kg of nonylphenol polyethylene oxide adduct of 0.014 kg and ion-exchanged water of 4.0 L
The solution consisting of is referred to as "Nonionic surfactant solution B".
223.8 g of potassium persulfate, 12.0 L of ion-exchanged water
The solution dissolved in was designated as "initiator solution C".

In a 100 L GL (glass lining) reactor equipped with a temperature sensor, a cooling pipe, and a nitrogen introducing device,
AX emulsion (polypropylene emulsion having a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration = 29.9%) 3.41 kg and "anionic surfactant solution A" and the total amount and "nonionic surfactant solution B" Add the whole amount and start stirring. The structure of the stirring blade is shown in Fig. 4.
The configuration of (c) is adopted. Next, ion-exchanged water 44.0L
Add.

When heating was started and the liquid temperature reached 75 ° C., the entire amount of “initiator solution C” was added dropwise. Then, while controlling the liquid temperature to 75 ° C ± 1 ° C, styrene 1
2.1 kg, n-butyl acrylate 2.88 kg, methacrylic acid 1.04 kg and t-dodecyl mercaptan 54
8 g and is added dropwise. After the dropping was completed, the liquid temperature was raised to 80 ° C. ± 1 ° C., and the mixture was heated and stirred for 6 hours. Then, the liquid temperature is cooled to 40 ° C. or lower, stirring is stopped, and the mixture is filtered with a pole filter to obtain “latex-A”.

The glass transition temperature of the resin particles in Latex-A is 57 ° C., the softening point is 121 ° C., the molecular weight distribution is weight average molecular weight = 127,000, and the mass average particle diameter is 12.
It was 0 nm.

A solution prepared by dissolving 0.055 kg of sodium dodecylbenzenesulfonate in 4.0 L of ion-exchanged pure water is referred to as "anionic surfactant solution D". Also,
A solution in which 0.014 kg of a 10-mol addition product of nonylphenol polyethylene oxide is dissolved in 4.0 L of ion-exchanged water is referred to as “nonionic surfactant solution E”.

Potassium persulfate (manufactured by Kanto Chemical Co., Inc.) 200.
A solution prepared by dissolving 7 g in 12.0 L of ion-exchanged water is referred to as "initiator solution F".

A 100 L GL reaction kettle equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a comb-shaped baffle (the structure of the stirring blade is shown in FIG. 4 (c)) was added to a WAX emulsion (polypropylene emulsion having a number average molecular weight of 3000: number average). Primary particle size = 120 nm / solid content concentration 29.9%) 3.4
1 kg, the total amount of "anionic surfactant solution D" and the total amount of "nonionic surfactant solution E" are added, and stirring is started.
Next, 44.0 L of ion-exchanged water is added. When heating is started and the liquid temperature reaches 70 ° C., “initiator solution F” is added. Next, 11.0 kg of styrene, 4.00 kg of n-butyl acrylate and 1.04 of methacrylic acid.
A solution in which kg and 9.02 g of t-dodecyl mercaptan were mixed in advance was added dropwise. After the dropping is completed, the liquid temperature is set to 7
The temperature was controlled to 2 ° C ± 2 ° C, and the mixture was heated and stirred for 6 hours. Furthermore, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours. The liquid temperature is cooled to 40 ° C. or lower and stirring is stopped. After filtering with a pole filter, this filtrate was designated as "latex-B".

The resin particles in Latex-B had a glass transition temperature of 58 ° C., a softening point of 132 ° C., a molecular weight distribution of weight average molecular weight = 245,000, and a mass average particle diameter of 11 ° C.
It was 0 nm.

Sodium chloride as a salting-out agent 5.36k
A solution prepared by dissolving g in 20.0 L of ion-exchanged water is referred to as “sodium chloride solution G”.

A solution prepared by dissolving 1.00 g of a fluorine-based nonionic surfactant in 1.00 L of ion-exchanged water is referred to as "nonionic surfactant solution H".

100 L of S equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, a particle size and shape monitoring device
In the US reactor (the structure of the stirring blade is shown in FIG. 4 (c)), the latex-A = 20.0 kg, the latex-B = 5.2 kg, the colorant dispersion liquid 1 = 0.4 kg, and the ion-exchanged water prepared above were added. Add 20.0 kg and stir. Then, 40
After heating to 0 ° C., sodium chloride solution G, 6.00 kg of isopropanol (manufactured by Kanto Chemical Co., Inc.), and nonionic surfactant solution H are added in this order. Then, after leaving it for 10 minutes, the temperature rise is started and the liquid temperature is raised to 85 ° C. in 60 minutes.
Particle diameter growth is performed while salting out / fusing by heating and stirring at 85 ± 2 ° C. for 0.5 to 3 hours (salting out / fusing step). Next, 2.1 L of pure water is added to stop grain size growth.

5.0 kg of the fused particle dispersion liquid prepared above was placed in a 5 L reaction vessel (a stirring blade configuration is shown in FIG. 4C) equipped with a temperature sensor, a cooling tube, and a particle size and shape monitoring device. 0.5 to 0.5 at the liquid temperature of 85 ℃ ± 2 ℃
The shape was controlled by heating and stirring for 15 hours (shape controlling step).
Then, the temperature is cooled to 40 ° C. or lower and stirring is stopped. Next, using a centrifuge, classification is performed in the liquid by a centrifugal sedimentation method, and the mixture is filtered through a sieve having an opening of 45 μm to obtain the filtrate as an association liquid. Then, using a Nutsche filter, wet cake-like non-spherical particles were collected from the association liquid by filtration. Then, it was washed with ion-exchanged water.

The non-spherical particles were dried at a suction temperature of 60 ° C. using a flash jet dryer, and then at a temperature of 60 ° C. using a fluidized bed dryer. To 100 parts by mass of the obtained colored particles, 1 part by mass of silica fine particles was externally added and mixed by a Henschel mixer to obtain a toner by an emulsion polymerization association method.

In the salting out / fusion step and the shape control step, the shape and the coefficient of variation of the shape coefficient are controlled by controlling the number of revolutions of the stirring blade and the heating time of the liquid temperature. By adjusting the variation coefficient of the particle size and the particle size distribution by classification, the toners 1-1 to 1-1 shown in Table 2
1-5 was obtained. The composition is styrene / n-butyl acrylate / methacrylic acid = 0.758 / 0.162 / 0.08
It was 0 mol% and the Tg of the resin was about 57 ° C.

Preparation of Toner 2-1 (Example of Emulsion Polymerization Association Method) As in the case of Toner 1-1, in the monitoring of the salting out / fusion step and the shape control step, the stirring rotation speed and the heating time should be controlled. To control the coefficient of variation of the shape and the coefficient of shape, and to further adjust the coefficient of variation of the particle size and the particle size distribution by in-liquid classification.
-1 was obtained. Also, the resin composition is styrene of toner 1-1 /
n-butyl acrylate / methacrylic acid = 0.758 /
From 0.162 / 0.080 mol%, styrene / n-butyl acrylate / n-butyl methacrylate = 0.8
Changed to 7 / 0.035 / 0.095 mol%. The Tg of the resin was 67 ° C.

Toners 3-1 to 3-2 (Example of Emulsion Polymerization Association Method) Similar to Toner 1-1, stirring rotation speed and heating time are controlled in the salting out / fusion step and monitoring of the shape control step. In this way, the variation coefficient of the shape and the shape factor is controlled, and the variation coefficient of the particle size and the particle size distribution is arbitrarily adjusted by the in-liquid classification, and the toner 3 shown in Table 2
-1 to 3-2 were obtained. The resin composition is styrene / n-butyl acrylate / n-butyl methacrylate = 0.67.
/0.03/0.30 mol%.

[0273]

[Table 2]

Preparation of Developer Mixing each of the toners 1-1 to 3-2 with a 45 μm ferrite carrier coated with a styrene-methacrylate copolymer at a ratio of 19.8 g of toner and 200.2 g of carrier, respectively. Thus, eight kinds of developers 1-1 to 3-2 corresponding to each toner were prepared.

Evaluation 2 (Image forming method using charging roller) <Evaluation conditions> The corona charger of the digital copying machine 7033 manufactured by Konica was changed to a charging roller, and the charging roller was brought into contact with the photoconductor, and the copying speed was changed. A4 was modified to 10 sheets / minute, and the live-action image evaluation was carried out. The copying machine 7033 has an image exposing device, a developing device, a transfer electrode, a cleaning device and a fixing device around the photoconductor in addition to the charging device, and has an image forming process of reversal development.

(Charging Roller) A charging roller composed of the following conductive elastic member and the like was used on a stainless steel cored bar of 8 mmφ.

Charging roller No. 1 As a material for the conductive elastic layer, polynorbornene rubber /
A carbon black / naphthene-based oil and, if necessary, a vulcanizing agent, a vulcanization accelerator, an additive and the like were mixed and prepared, and then filled in a mold to form a conductive elastic layer. On this layer, polyester urethane as a coating layer forming material, particle size of about 0.5
Immersed in a composition liquid consisting of a resin powder (μm), carbon black, and a solvent (MEK / dimethylformamide), coated, dried, and heat-treated to form a coating layer composed of a urethane layer, and a surface roughness Rz: 5 5 μm charging roller No. Got 1.

Charging roller No. No. 2 except that a resin powder having a particle size of about 8 μm was used as the coating layer forming material instead of the resin powder having a particle size of about 0.5 μm.
In the same manner as in No. 1, charging roller No. 1 having surface roughness Rz: 6.5 μm. Got 2.

Charging roller No. 3 As a material for the conductive elastic body layer, carbon black is dispersed in urethane foam rubber, and if necessary, a vulcanizing agent, an antioxidant, an additive and the like are mixed and prepared, and the conductive elastic layer is used. Formed and further polished. On this layer, as a coating layer forming material, polyacrylic urethane, carbon black, dipping in a composition liquid consisting of a solvent, coating,
After being dried and heat-treated, the charging roller No. 1 having a surface roughness Rz of 8.5 μm was used. Got 3.

The surface roughness Rz (ten-point average roughness) was measured with a surface roughness meter (Surfcom-550A manufactured by Tokyo Seimitsu Co., Ltd.).

Charging conditions Photoconductor contact pressure: 50 g / cm DC voltage applied to the charging member: -600 V, AC voltage: 2,000 Vp-p, frequency: 150 Hz Development condition DC bias: -500 V Dsd (with photoconductor) Distance between developing sleeves): 600 μm Developer layer regulation; Magnetic H-Cut system developer layer thickness; 700 μm Developing sleeve diameter: 40 mmφ Further, as a fixing method, thermal roll fixing is used, and untransferred toner remaining on the photoreceptor Adopted a method of cleaning with a blade cleaning method.

As the transfer paper to be used, a paper having a continuous weight of 55 kg was used. Evaluation item A combination of the photoreceptor, toner (developer) and charging roller described in Table 3 (Examples 1 to 10 and Comparative Example 1,
2) Attach the photoconductor, developer, charging roller, etc. to a modified Konica digital copying machine 7033, and 30 ° C, 80% RH
Under the environment, 100,000 copies were actually copied, and the following evaluation items were evaluated.

For copying, an original image in which a character image with a pixel ratio of 7%, a human face photograph, a solid white image, and a solid black image are equally divided into four parts is copied in A4 to obtain a solid white image and a solid black image. Images and thin line images were evaluated.

The judgment criteria for each evaluation item are as follows. Crack evaluation The surface of the sample coated up to the intermediate layer was observed to see if cracks occurred. After that, a photoconductor was prepared, 100,000 copies were actually copied under the above environmental conditions, and evaluated according to the following evaluation criteria.

⊚: No cracks are generated in the intermediate layer or fine cracks that do not appear in the image, no problem ○: Minor cracks appearing in the image are generated in the intermediate layer, practically no problem ×: In the intermediate layer Cracks grow and grow on the image,
There is a problem in practical use. Adhesion evaluation After copying 100,000 sheets, film peeling of the photoconductor was evaluated. The evaluation criteria are shown below.

⊚: No film peeling ○: There is slight film peeling at the edges, but not in the image area.
No problem in practical use x: Film peeling occurred in the image area. Practically problematic fog: Judgment by solid white image density For fog, after copying 100,000 sheets, the density of each image was measured for absolute reflection density using RD-918 manufactured by Macbeth. If the increase in residual potential increases, the image density decreases, and if the decrease in charging potential increases, fogging occurs.
Further, if the uniformity of the charging potential decreases, the image unevenness increases.

⊚: Solid white image density is less than 0.005 (good) ○: Solid white image density is 0.005 or more and less than 0.01 (no problem in practical use) ×: 0.01 or more (problem in practical use) Sharpness: Judgment by fine line image Sharpness was visually judged after the number of fine lines per 1 mm that can be discriminated by the copy image of the fifth generation was prepared after copying 100,000 sheets.

⊚: 6 lines / mm or more (good) O: 4 lines / mm or more and 5 lines / mm or less (at a level where there is no practical problem) ×: 3 lines / mm or less (with practical problems) Image unevenness: 100,000 0.4 after copying the original image
Copy the halftone image of the density of 0.4 to the density of 0.4, and judge by the density difference of the copied images (ΔHD = maximum density−minimum density) ◎: ΔHD is 0.05 or less (good) ○: ΔHD is more than 0.05 Larger than 0.1 (no problem in practical use) ×: ΔHD is 0.1 or more (problem in practical use) Black spots Black spots have a major axis of 0.4 m after 100,000 copies.
It was judged by the number of black spots of m or more per A4 sheet.
The major axis of the black spot can be measured with a microscope equipped with a video printer.

⊚: Black spot frequency of 0.4 mm or more: All copied images were 3
No./A4 or less ○: 0.4 mm or more black spot frequency: 4 / A4 or more, 1
9 or more / A4 or less occurred 1 or more (no problem in practical use) ×: 0.4 mm or more black spot frequency: 20 / A4 or more occurred 1 or more (problem in practical use) Evaluation results are shown in Table 3. .

[0290]

[Table 3]

From Table 3, in the contact charging type image forming method using a charging roller, photoreceptors 1 to 1 having an intermediate layer in which the intermediate layer of the present invention contains N-type semiconductive particles to form a Benard cell are formed. In Examples 7 and 10 (Examples 1 to 10), the occurrence of cracks in the intermediate layer and the peeling of the film were suppressed, and good characteristics were exhibited in the image evaluation as well. Photoreceptor 8 Using Intermediate Layer
In (Comparative Example 1), no Benard cell was formed, and as a result, cracks and film peeling occurred, black spots and image unevenness were frequently generated, and sharpness was also deteriorated. Further, also in the photoreceptor 9 (Comparative Example 2) of the intermediate layer using silica particles (non-semiconductive particles), the generation of Benard cells is weak and the generation of black spots is large. Further, in the combination of the photoconductor and the toner, even if the photoconductor 1 or 2 of the present invention is used, the variation of the shape factor of the toner is larger than 16% (Example 9), and the number variation coefficient of the number particle size distribution. The sharpness is slightly lowered in the combination (Example 10) in which the ratio is larger than 27%.

Evaluation 3 (Image forming method using magnetic brush) <Evaluation conditions> The corona charger of the Konica digital copying machine 7033 was changed to a magnetic brush charger, and the copy speed was changed to A4, 10 sheets / minute. It was remodeled and a live-action film was evaluated. The conditions other than the charging condition are the same as the conditions of the charging roller.

(Magnetic Brush Charger) It has the structure of FIG.

Preparation of Magnetic Particles Magnetic particles forming a magnetic brush for charging were prepared as follows.

Preparation of Magnetic Particles 1 Fe ₂ O ₃ : 50 mol% CuO: 24 mol% ZnO: 24 mol% The above are crushed and mixed, and a dispersant, a binder and water are added to make a slurry, followed by granulation with a spray dryer. After operation and classification, firing was performed at 1125 ° C. The obtained magnetic particles were crushed and then classified to obtain magnetic particles 1 having a volume average particle diameter of 27 μm. The magnetic particles had a resistivity of 2 × 10 ⁷ Ωcm and a magnetization intensity of 65 emu / g.

Preparation of Magnetic Particles 2 0.05 parts by mass of a titanium coupling agent (isopropoxytriisostearoyl titanate) and methyl ethyl ketone were added to 100 parts by mass of the above-mentioned magnetic particles 1,
After stirring to form an organic coating on the surface of the magnetic particles, the magnetic particles were separated and dried by heating at 180 ° C. Magnetic particles 2 having a volume average particle diameter of 37 μm were obtained. The magnetic particles had a resistivity of 2 × 10 ⁷ Ωcm and a magnetization intensity of 70 emu / g.

Preparation of Magnetic Particles 3 Fe ₂ O ₃ : 50 mol% MnO: 30 mol% MgO: 20 mol% The above are crushed and mixed, and a dispersant, a binder and water are added to make a slurry, and the mixture is granulated with a spray dryer. After operation and classification, firing was performed at 1130 ° C. in an atmosphere in which oxygen concentration was adjusted for resistance adjustment. The obtained magnetic particles are crushed and then classified to obtain a volume average particle size of 70.
Magnetic particles 3 having a size of μm were obtained. The resistivity of magnetic particles is 9 ×
It was 10 ⁵ Ωcm and the strength of magnetization was 63 emu / g.

Method for Measuring Volume Average Particle Diameter of Magnetic Particles The volume average particle diameter of the carrier is typically measured by a laser diffraction type particle size distribution measuring apparatus “Heros (H
ELOS) "(manufactured by SYMPATEC).

Method for measuring resistivity (Ωcm) Magnetic particles were placed in a container having a cross-sectional area of 0.50 cm ² and tapped, and then 1 kg / cm on the packed particles.
^Apply a load of ² , and apply 1000V / between the load and the bottom electrode.
A value obtained by reading the current value when a voltage that causes an electric field of cm is applied.

Charging conditions Charging sleeve; voltage applied to a 10 mmφ stainless steel charging sleeve; AC voltage superimposed on DC voltage 450 V; amount of magnetic particles in charging region; 250 mg / cm ² linear velocity ratio of charging sleeve / photoreceptor; 0 .8 A photoconductor, a toner (developer), and a magnetic brush using magnetic particles, which are combined as shown in Table 4, are mounted on a modified machine of the digital copying machine 7033 manufactured by Konica, and the ambient temperature and humidity (20 ° C. 6
The image output of 100,000 sheets was evaluated under 0% RH). The evaluation method was the same as that for the charging roller.

<Evaluation>

[0302]

[Table 4]

From Table 4, in the contact charging type image forming method using a magnetic brush, photoreceptors 1 to 1 having an intermediate layer containing N-type semiconductive particles in the intermediate layer of the present invention to form a Benard cell In Examples 7 and 10 (Examples 11 to 20), the generation of cracks in the intermediate layer and the peeling of the film were suppressed, and good properties were exhibited in the image evaluation as well. In the photoconductor 8 using the intermediate layer (Comparative Example 3), no Benard cell was formed, and as a result, cracks and film peeling occurred, black spots and image unevenness frequently occurred, and the sharpness also deteriorated. Further, also in the photoconductor 9 (Comparative Example 4) of the intermediate layer using silica particles (non-semiconductive particles), the generation of Benard cells is weak and the generation of black spots is large. Further, in the combination of the photoconductor and the toner, even if the photoconductor 1 or 2 of the present invention is used, the variation of the shape factor of the toner is larger than 16% (Example 19), and the number variation coefficient of the number particle size distribution. The sharpness is slightly reduced in the combination (Example 20) in which the ratio is larger than 27%.

[0304]

INDUSTRIAL APPLICABILITY By using the electrophotographic photoreceptor containing the N-type semiconductive particles of the present invention and a binder and having an intermediate layer of an insulating layer in which a Benard cell is formed, a contact charging type image forming method can be obtained. Also, cracks and film peeling do not occur on the photoconductor, and a good copy image without image defects can be obtained. Further, it is possible to provide an image forming apparatus using the image forming method.

[Brief description of drawings]

FIG. 1A is an explanatory diagram showing a projected image of toner particles without corners, and FIGS. 1B and 1C are explanatory diagrams showing projected images of toner particles with corners.

FIG. 2 is a perspective view showing an example of a polymerized toner reaction device.

FIG. 3 is a cross-sectional view showing an example of a polymerized toner reaction device.

FIG. 4 is a schematic view showing a specific example of the shape of a stirring blade.

FIG. 5 is a diagram illustrating an example of an image forming apparatus that performs roller charging.

FIG. 6 is a diagram of a contact type magnetic brush charging device.

7 is a diagram showing a relationship between an AC bias voltage and a charging potential by the charging device of FIG.

FIG. 8 is a sectional view showing an example of an image forming apparatus having a magnetic brush charger of the present invention.

FIG. 9 is a diagram in which a large number of polygons are formed in front, rear, left and right (Benard cell structure).

[Explanation of symbols]

1 charging roller 2 photoconductor drum 3 developing device 4 Development sleeve 5 Static elimination lamp 6 Transfer roller 7 Conveyor belt 8 Conveyor rollers 20 core metal 50 photoconductor drum 51 exposure section 52 Magnetic brush charger 53 Image exposure device 54 Developer 120 Magnetic brush charging device 120a charging sleeve 220 supply bottles 300 Magnetic particle recovery container

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Hamaguchi             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house F-term (reference) 2H005 AA15 EA05 EA07                 2H068 AA43 AA44 BA58 BB28 CA06                       CA29 CA60 FA27 FC01 FC08                 2H200 FA09 GA16 GA23 GA30 GA34                       GA44 GA53 GB12 HA02 HA21                       HA28 HA29 HA30 HB12 HB17                       HB22 HB43 HB45 HB46 HB47                       HB48 LC03 MA01 MA03 MA12                       MA14 MA17 MA20 MB01 MB06                       MC06 MC11 MC13 MC15 NA06                       NA09 NA10 PA03 PA19 PA22                       PA27 PB02 PB04 PB05 PB33

Claims (20)

[Claims] 1. An image forming method for forming an image on an electrophotographic photosensitive member through a charging step, an exposing step and a developing step, wherein the electrophotographic photosensitive member contains N-type semiconductive particles and a binder. An image forming method, further comprising an intermediate layer of an insulating layer in which a Benard cell is formed, and the charging step is performed by bringing a charging member into contact with the electrophotographic photosensitive member to charge the electrophotographic photosensitive member. 2. The image forming method according to claim 1, wherein the charging member is a charging roller. 3. The image forming method according to claim 1, wherein the charging member is a magnetic brush charging device. 4. The N-type semiconductor particles have been subjected to surface treatment a plurality of times, and the final surface treatment is a surface treatment with a reactive organosilicon compound.
4. The image forming method according to any one of 3 to 3. 5. The image forming method according to claim 4, wherein the reactive organosilicon compound is methylhydrogenpolysiloxane. 6. The image forming method according to claim 4, wherein the reactive organosilicon compound is an organosilicon compound represented by the following general formula (1). General formula (1) R-Si- (X) ₃ (R is an alkyl group, an aryl group, X is a methoxy group, an ethoxy group, a halogen group.) 7. R in the general formula (1) has 4 to 8 carbon atoms.
The image forming method according to claim 6, wherein the alkyl groups are up to. 8. The surface treatment of at least one of the plurality of surface treatments is a surface treatment of one or more compounds selected from alumina, silica, and zirconia. The image forming method according to any one of 1. 9. The image forming method according to claim 1, wherein the N-type semiconductor particles are surface-treated with an organic silicon compound having a fluorine atom. 10. The image forming method according to claim 1, wherein the N-type semiconducting particles are particles having a number average primary particle diameter of 10 nm or more and 200 nm or less. 11. The image forming method according to claim 1, wherein the N-type semiconductive particles are metal oxide particles. 12. The image forming method according to claim 11, wherein the metal oxide particles are titanium oxide particles. 13. The image forming method according to claim 1, wherein the binder of the intermediate layer is a polyamide resin. 14. The dry film thickness of the intermediate layer is 0.2 to 15 μm.
m is any one of Claims 1-13 characterized by the above-mentioned.
The image forming method according to item. 15. The toner in which the variation coefficient of the shape factor of the toner particles is 16% or less and the number variation coefficient of the number particle size distribution is 27% or less in the developing step. 15. The image forming method according to any one of 14. 16. A shape factor of 1.0 to in the developing step.
The image forming method according to any one of claims 1 to 15, characterized in that a toner having 65% by number or more of toner particles in the range of 1.6 is used. 17. The image forming method according to claim 1, wherein a toner containing 50% by number or more of toner particles having no corners is used in the developing step. 18. The number average particle size in the developing step is from 3 to 3.
A toner having a size of 8 μm is used.
The image forming method according to any one of items 1 to 17. 19. In the developing step, when the particle diameter of the toner particles is D (μm), the natural logarithm lnD is plotted on the horizontal axis,
This horizontal axis is divided into a plurality of classes at intervals of 0.23, and the relative frequency (m ₁ ) of the toner particles included in the most frequent class in the histogram showing the number-based particle size distribution and the frequency next to the most frequent class 19. The image forming method according to claim 1, wherein a toner having a sum (M) of a relative frequency (m ₂ ) of toner particles included in a high class is 70% or more is used. . 20. An image forming apparatus using the image forming method according to claim 1. Description: