JP3508392B2 - Electrostatic latent image developer carrier, electrostatic latent image developer, image forming method and image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier for an electrostatic latent image developer used for developing an electrostatic latent image in electrophotography and electrostatic recording, an electrostatic latent image developer, and image formation. The present invention relates to a method and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, an electrostatic latent image is formed on a photoconductor or an electrostatic recording medium by using various means.
A method is generally used in which electrostatic detecting particles called toner are attached to the electrostatic latent image to develop the electrostatic latent image. During this development, carrier particles called carrier are mixed with toner particles, and both are triboelectrically charged,
The toner is given an appropriate amount of positive or negative charge.

Carriers are generally classified into a coated carrier having a coating layer on the surface and a non-coated carrier having no coating layer on the surface. In consideration of the life of the developer, the coated carrier is more preferable. Therefore, various types of coated carriers have been developed and put into practical use. Although there are various characteristics required for the coating film carrier, it is required to stably impart an appropriate chargeability (charge amount and charge distribution) to the toner and maintain the appropriate and stable chargeability for a long period of time. . To this end, the carrier has suitable electrical properties, and is highly resistant to environmental changes such as humidity and temperature, has high impact resistance and abrasion resistance, and its chargeability does not change over a long period of time. Life is important, and various coated carriers have been proposed.

As a solution to some of these problems, JP-A-61-80161 and JP-A-61-801 have been proposed.
No. 62 and No. 61-80163 disclose copolymers of nitrogen-containing fluorinated alkyl (meth) acrylates and vinyl monomers, and copolymers of fluorinated alkyl (meth) acrylates and nitrogen-containing vinyl monomers. It is described that a coated carrier having a relatively long life is obtained by coating the surface of the carrier core material with the coalescence.

Further, a polyamide resin in JP-A-1-118150 and a melamine resin in JP-A-2-79862 are coated on the surface of a carrier core material and further cured to form a coated carrier having a relatively hard coating. It is described to obtain.

However, none of the above methods can prevent the toner component from being contaminated (spent) on the carrier surface and are not satisfactory. In other words, the carrier is required to have a toner transporting function and at the same time a function to stably apply electric charges to the toner for a long period of time, but the carrier surface is contaminated by the toner and the latter function does not work effectively. .

In order to prevent such a spent,
It is preferable to use a silicone resin as described in JP-A-60-186844 and a fluorine-based resin as described in JP-A-64-13560. However, even when these resins are used at the same time as the above-mentioned polymer or resin and the surface of the carrier core material is coated, there are many silicone resins and fluororesins in the upper layer of the coating layer. The coating wears from the surface of the carrier during use, and eventually the silicone resin and the fluorine-based resin are lost, and in the long term, the spent prevention is no longer sufficient.

Further, in JP-A-3-213878, an acrylic resin containing fine particles of a crosslinked polymer is coated on the surface of a carrier core material to further increase the coating thickness and to impart a suitable chargeability to a carrier. It is described subsequently to obtain a long-lived coated carrier. However, since these fine particles have a weak degree of crosslinking and swell in an organic solvent, the expected purpose has not been sufficiently fulfilled. That is, since the fine particles swell in the step of coating the surface of the carrier core material, it takes time to evaporate the solvent or the solvent is distilled off from the swollen particles, so that the volume decreases and the coating becomes uniform. Therefore, the sufficient longevity of charge imparting property cannot be achieved.

Further, in relation to the drawbacks of the carrier described above, a carrier characterized by the selection of the resin to be used, but the resin is not limited to a specific type, is disclosed in Japanese Patent Application Laid-Open No. 1-58242.
It is disclosed in Japanese Patent Publication No. 105264. This is a carrier containing a plurality of incompatible resins and conductive fine powder in the coating layer. However, it cannot be said that this technique also sufficiently solves the above-mentioned various problems.

[0010]

In short, conventionally, due to structural or manufacturing reasons, there has been a problem in extending the life of the carrier, and on the other hand, the problem of spent also exists.

Thus, the first object of the present invention is to provide a carrier for electrostatic latent image development which has a very long life and is capable of preventing spent on the carrier surface by toner for a long period of time. is there.

A second object of the present invention is to provide an electrostatic latent image developer utilizing such carrier.

A third object of the present invention is to provide an image forming method capable of forming a high quality image by using such a carrier.

A fourth object of the present invention is to provide an image forming apparatus using such a carrier as an element.

[0015]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted intensive studies and studied mainly an electrostatic latent image developing carrier in order to improve the above-mentioned drawbacks in the prior art. By adopting the configuration, we succeeded in solving the above problems.

That is, the carrier for an electrostatic latent image developer of the present invention capable of achieving the first object has a critical surface tension of 40 to 70 dyn / cm on average in the matrix resin.
A resin coating layer in which thermosetting resin fine particles containing nitrogen atoms having a secondary particle diameter of 0.1 to 2 μm are dispersed and contained has a shape factor SF1 represented by the general formula (1) represented by the following formula (x). And the shape factor SF2 represented by the general formula (2) is provided on the core material satisfying the condition represented by the following formula (y). SF1 = (maximum length of diameter) ² / (area of carrier core material particles) × 100π / 4 (1) SF2 = (perimeter of projected image) ² / (area of carrier core material particles) × 100 / (4π) (2) 100 ≦ SF1 ≦ 145 (x) 100 ≦ SF2 ≦ 120 (y )

In this carrier, the resin coating layer has as its constituent elements a matrix resin and thermosetting resin fine particles containing a predetermined nitrogen atom which have different structures, and mainly the matrix resin provides a stable chargeability, Improves anti-spent property, while mainly containing specified nitrogen atom
The thermosetting resin fine particles can improve the mechanical strength. Therefore, it is possible to exert a stable chargeability-imparting ability, mechanical strength, and a spent prevention function over a long period of time.

Furthermore, since the thermosetting resin fine particles containing nitrogen atoms have a predetermined critical surface tension, they are easily dispersed uniformly in the matrix resin. Thus, it is suitable for stably exhibiting the above functions. Further, by this uniform dispersion, even if the resin coating layer is worn from the surface due to long-term use, the same surface composition as when not in use can be maintained, and even when the above-mentioned functions are seen in the long term. It can be maintained stable.

Furthermore, since the thermosetting resin fine particles containing nitrogen atoms do not swell in the organic solvent at the time of manufacturing the carrier, nonuniformity of the coating film due to the volume change does not occur. Then, nitrogen
If the average particle size of the thermosetting resin fine particles containing elementary atoms is smaller than 0.1 μm, the dispersion in the coating layer is poor and it is difficult to obtain a uniform composition of the resin coating layer. , There is a tendency that the original function cannot be maintained. Further, SF1 of the core material is expressed by the above formula (x), S
When F2 satisfies the formula (y), a uniform film can be easily formed at the time of resin coating, the charge distribution of the toner can be narrowed, the toner impaction is suppressed, and the charge imparting ability can be more stably maintained.

The electrostatic latent image developer of the present invention which can achieve the second object is an electrostatic latent image developer comprising the carrier and toner.

In the image forming method of the present invention which can achieve the third object, the electrostatic latent image bearing member is electrostatically charged by using the developer layer containing the toner and the carrier on the developer bearing member. In the image forming method for developing a latent image, the above-mentioned carrier for electrostatic latent image developer is used as the carrier.

In the image forming apparatus of the present invention which can achieve the above-mentioned fourth object, an electrostatic latent image bearing member is formed by using a developer layer containing a toner and a carrier on the developer bearing member. An image forming apparatus for developing a latent image is characterized in that the carrier is the predetermined electrostatic latent image developer carrier.

According to the above electrostatic latent image developer, image forming method and image forming apparatus, a high quality image can be obtained for a long period of time.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to embodiments.

One form of the carrier for the electrostatic latent image developer of the present invention is shown in FIG. The carrier 1 has a resin coating layer 20 in which thermosetting resin fine particles 22 containing nitrogen atoms having specific physical properties are dispersedly contained in a matrix resin 21,
It has on the core material 30. In the following, nitrogen atoms are not included.
The thermosetting resin fine particles are simply replaced with the thermosetting resin fine particles.
Let's say.

The thermosetting resin particles, in the matrix resin, the thickness direction of the coating layer, preferably are also dispersed as homogeneously as possible in the tangential direction of the carrier surface. At the same time, it is preferable that the matrix resin of the resin coating layer is also uniform. As a result, the charge imparting ability and the spent preventing function uniformly act on the entire carrier, and the function can be stably exhibited. Moreover, even when the resin coating layer is worn from the surface due to long-term use, the same surface composition as when not in use can be maintained at all times, and the above function can be maintained for a long time.

The resin fine particles dispersed in the resin coating layer, as described above, the thermosetting resin fine particles are used. This is because the hardness of the carrier can be increased, its durability can be improved, and there is no risk of swelling in the organic solvent used during production. The thermosetting resin has a critical surface tension of 20 dyn.
It is necessary to use those having a thickness of / cm or more. In this case, excellent dispersion stability of the matrix resin of the thermosetting resin fine particles, the fine particles is because particularly uniformly dispersible in the matrix resin. From this viewpoint, the critical surface tension is preferably 40 to 70 dyn / cm.

Examples of the thermosetting resin which can satisfy the requirement that the critical surface tension is 20 dyn / cm or more are phenol resin; amino resin such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin and polyamide resin; Epoxy resin; diallyl phthalate resin; unsaturated polyester resin; polyimide resin;
Alkyd resin; xylene resin; petroleum resin; furan resin and the like. The resin fine particles may be used alone or in combination of two or more of them, or each of the resin fine particles may be composed of one or more of these.

Further, the resin fine particles preferably contain an N atom having an electron donating property as a constituent component thereof in order to impart a negative charging property to the toner.

The resin fine particles may be produced by any method, but for example, it can be produced by the following method as crosslinked resin particles.

That is, a method for producing a granular resin by using a polymerization method such as suspension polymerization, emulsion polymerization, suspension polymerization, or the like. And a method of mixing and reacting the low-molecular component and the cross-linking agent by melt-kneading, and then pulverizing to a predetermined particle size by wind force or mechanical force. The fine resin particles are preferably in the form of fine particles before being mixed and dispersed in the carrier resin. This is because it is easy to ensure the uniformity of the mixing and dispersion and to confirm the uniformity of the dispersion.

The average primary particle size of the resin fine particles is 0.1 to 2
μm , and preferably 0.2 to 1 μm. 0.1
When it is less than μm, the dispersion in the coating layer is poor, and it is difficult to obtain a uniform composition of the resin coating layer. When it is more than 2 μm, the resin layer is likely to fall off and the original function tends to be unable to be maintained.

The average film thickness of the resin coating layer formed as described above is usually 0.1 to 10 μm, preferably 0.2.
˜3 μm range. The average thickness of this resin coating layer is ρ _{D for} the specific gravity of the carrier core material, D for the average particle diameter of the carrier core material, ρ _{C for} the average specific gravity of the resin containing the coated resin particles,
When the total coating amount of the resin is W _C , it is easily calculated by the following formula.

Film thickness (A) = [amount of coating resin per carrier (including resin particles) / surface area per carrier] / average specific gravity of coating resin = [4 / 3π. (D / 2) ³・ Ρ _D・ W _C ] / [4π
^{(D / 2) 2] ÷} ρ C = (1/6) · In a particularly preferred form of the carrier _{(D · ρ D · W C} / ρ C) the present invention, the thermosetting tree <br/> fat particles The average primary particle diameter (B) satisfies (B) ≦ (A) with respect to the average thickness (A) of the resin coating layer. When resin particles having an average primary particle diameter larger than the thickness of the resin coating layer are used, resin particles that deviate from the state where the resin particles are sufficiently embedded in the coating layer can be seen. Therefore, these resin particles are likely to fall off due to a relatively small mechanical force from the outside, and the desired charge imparting ability to the toner may not be sufficiently exhibited. Further, the mechanical force from outside at the time of resin coating layer formed in the carrier surface, for so also ubiquitous thermosetting resin fine particles occurs, the surface composition of the resin coating layer becomes uneven, the toner charge distribution is widened It will be easier. In this way, variations in the density and fog of the copied image can be brought about.

From the above viewpoint, more preferably (B)
≦ 0.8 (A), more preferably (B) ≦ 0.5
(A).

In the present invention, it is desirable that the number particle size distribution of the resin fine particles is controlled within a certain range. Specifically, 1/2 × ratio of d ₅₀ below fine particles having a particle size of 20% by number or less, it is preferable that the ratio of the fine particles having a particle size of 2 × d ₅₀ or more is 20% by number or less. In addition, d ₅₀ is a number average particle diameter.

When the proportion of fine particles having a particle size of ½ × d ₅₀ or more exceeds 20% by number, a large number of small-sized fine particles agglomerate with each other, so that the uniformity of the composition of the coating layer deteriorates. . Further, the property of imparting contact charge to the toner is unstable. On the other hand, when the proportion of fine particles having a particle size of 2 × d ₅₀ or more exceeds 20% by number, deviation from the coating layer is likely to occur, and the charge imparting property to the toner changes with the use of the developer. As a result, stability is impaired.

In the present invention, the particle size distribution of the resin fine particles means a value measured as follows. Observe with a scanning electron microscope and take a photograph at a magnification of 5000 times. Then, the hydrophobic inorganic fine particles and the colored particles are binarized with respect to the photographed photograph using an image analyzer, and then the number particle size distribution is obtained from the circle-equivalent diameter of about 100 randomly selected hydrophobic inorganic fine particles. As described above, the hydrophobic inorganic fine particles used for the measurement of the particle size distribution are treated as one particle as long as the particles can behave as a unit particle, regardless of whether they are primary particles or secondary particles. I shall. Further, in the present invention, "number average particle size"
The term "particle size" refers to the particle size when the cumulative number distribution reaches 50%, and is generally called the number median diameter.

The total amount of the resin fine particles in the resin coating layer is usually 1 to 50, preferably 5 to 30, and more preferably 5 to 5.
20% by volume.

The matrix resin of the resin coating layer containing the resin particles may be selected from any resin that can be used in the art as a coating layer for a carrier. The resin may be one kind or two or more kinds.

Specifically, polyolefin resins such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylcarbazole, polyvinyl. Ethers and polyvinyl ketones; vinyl chloride-vinyl acetate copolymers; styrene-acrylic acid copolymers; straight silicone resins consisting of organosiloxane bonds or modified products thereof; fluororesins such as polytetrafluoroethylene.
Polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyester; polyurethane;
Polycarbonates; phenol resins; amino resins such as urea-formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins; epoxy resins and the like.

In the electrostatic latent image developing carrier, the critical surface tension (γc) is preferably used as the matrix resin.
35 dyn / cm or less, more preferably 30 dyn / cm
A resin having a size of cm or less is used. This matrix resin has low energy on the surface of the carrier, and the spent on the surface by the toner can be sufficiently suppressed.

Examples of the resin having a critical surface tension of 35 dyn / cm or less include the following resins.

Polystyrene (γc = 33 dyn / c
m), polyethylene (γc = 31 dyn / cm), polyvinyl fluoride (γc = 28 dyn / cm), polyvinylidene fluoride (γc = 25 dyn / cm), polytrifluoroethylene (γc = 22 dyn / cm), polytetrafluoroethylene (Γc = 18 dyn / cm), polyhexafluoropropylene (γc = 16 dyn / cm),
In addition to those such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, terpolymers of tetrafluoroethylene and vinylidene fluoride and non-fluorinated monomers Such fluoroterpolymers and the like.

Particularly, it is preferable to contain a fluorine-containing resin, polymer and / or silicone resin having a critical surface tension of 30 dyn / cm or less.

The matrix resin and the resin of the resin fine particles may be of the same kind as long as they can be classified into such forms depending on the difference in the production method and the molecular weight.

In the carrier, the core material (carrier core material) on which the resin coating layer is provided is not particularly limited with respect to its type and manufacturing method, and a method used in the art can be used. Examples thereof include magnetic metals such as iron, steel, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. From the viewpoint of using the magnetic brush method, magnetic carriers are preferable. Also, the saturation magnetization is not too high, and the relatively small specific gravity of ferrite causes less mechanical stress on the toner,
More preferable.

Taking ferrite as an example, the carrier core material is generally manufactured as follows. As an initial raw material,
Metal oxides that have been sized to 10 μm or less in advance are used as Fe.
₂ O ₃ : MgO: ZnO: MnO ₂ : CuO = 50: 2
It is prepared at a ratio of 5: 20: 1: 4 mol%, mixed with a Henschel mixer or the like, and then temporarily sintered in a kiln at 900 ° C. for 3 hours. The powder that has undergone the quasi-spinelization reaction by temporary sintering is mixed with water and pulverized with a ball mill for 10 hours. To this aqueous solution, a binder (polyvinyl alcohol) and a dispersant are added by several% by weight to obtain a slurry solution. The slurry is granulated and dried, and the granulated pellets are
It is fired in an electric furnace at 300 ° C. for 4 hours to obtain a ferrite powder composed of appropriate primary particles. This is sieved to remove coarse powder and fine powder to obtain carrier core particles having desired particle size and electric resistance.

Cavities are formed in the bonding surface of the primary particles due to the crystal growth of the primary particles during sintering, and the generation ratio affects the shape factor, but it depends on the properties of the raw materials, additives, firing, crushing, and other conditions. Controlled.

The average particle size of the carrier core material is generally 10 μm to 150 μm, preferably 30 μm to 100 μm.

The career of the present invention, with respect to the carrier core material, the general formula (1), the shape factor SF1 and shape factor SF2 respectively represented by (2), represented by the following formula (x), the following formula (y) to satisfy the conditions. SF1 = (maximum length of diameter) ² / (area of carrier core material particles) × 100π / 4 (1) SF2 = (perimeter of projected image) ² / (area of carrier core material particles) × 100 / (4π) (2) 100 ≦ SF1 ≦ 145 (x) 100 ≦ SF2 ≦ 120 (y) is satisfied.

The above shape factor is used as a coefficient for expressing the form such as the shape of the carrier core material, and the area, length, shape, etc. of the image captured by the optical microscope or the like can be quantitatively analyzed with high accuracy. It is based on a statistical method called image analysis and can be measured by an image analyzer [manufactured by Nippon Regulator Co., Ltd., model Luzex 5000].

As is clear from the equation (1), SF1 is obtained by dividing the value obtained by squaring the maximum length of the diameter of the carrier core particles by the area of the carrier core particles, and multiplying by π / 4. 10
It is a value obtained by multiplying it by 0. The closer the shape of the carrier core material particle is to a sphere, the closer to 100, and conversely, the longer the shape, the larger the value. That is, it represents the difference between the maximum diameter and the minimum diameter of the carrier core material, that is, the strain. SF2 is, as is clear from the equation (2), a value obtained by dividing the squared length of the circumference of the projected image of the carrier core particles by the area of the carrier core particles, and multiplying by 1 / 4π, and It is a value obtained by multiplying by 100. The closer the carrier core particle shape is to a sphere, the closer it is to 100, and the more complex the surrounding shape, the larger the value. That is, it expresses the carrier core material surface area (irregularity). If perfect spherical, SF1 = SF2 = 100
Is.

SF1 is the above formula (x), and SF2 is the above formula (y).
When the above condition is satisfied, a uniform film can be easily formed at the time of resin coating, the charge distribution of the toner can be narrowed, the toner impaction is suppressed, and the charge imparting ability can be maintained more stably.

In the electrostatic latent image developing carrier of the present invention, as a method for forming the resin coating layer on the surface of the carrier core material, typically, a resin coating layer forming raw material solution (in a solvent, A matrix solution and at least resin fine particles are used). Specifically, for example, the powder of the carrier core material is immersed in a coating layer forming solution, a dipping method of spraying the coating layer forming solution on the surface of the carrier core material, the carrier core material by flowing air. A fluidized bed method of spraying a coating layer forming solution in a suspended state, a carrier core material and a coating layer forming solution in a kneader coater are mixed, and a kneader coater method of removing the solvent can be mentioned. The kneader coater method is particularly preferably used.

The solvent used for the raw material solution for forming the coating layer is
There is no particular limitation as long as it can dissolve the matrix resin, and for example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used.

Since it is preferable that the resin fine particles are already in the form of fine particles in the solvent, it is preferable that the resin fine particles are substantially insoluble in the solvent (solvent insoluble). As a result, the resin fine particles do not aggregate in the resin coating layer and maintain the form of primary particles.

If the resin fine particles are evenly dispersed in the resin coating layer to be formed if they are uniformly dispersed in the solvent, it is preferable to prepare the raw material solution for forming the coating layer in such a manner. Since such a uniform dispersion is a solution, it can be achieved very easily. For example, it is sufficient to stir the entire raw material solution.

The electrostatic latent image developing carrier of the present invention is used with an electrostatic latent image developer of any kind to form an electrostatic latent image developer.

There are no particular restrictions on the types of the colorant and the binder resin, which are the constituent components of the toner, and examples of the colorant include carbon black, nigrosine, aniline blue,
Calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment Red 48: 1, C.I.
I. Pigment Red 122, C.I. I. Pigment
Red 57: 1, C.I. I. Pigment Yellow 97,
C. I. Pigment Yellow 12, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 1
5: 3 etc. can be illustrated as a typical thing.

Examples of the binder resin include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl acetate, and acrylic acid. Α-Methylene aliphatic monocarboxylic acid ester such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl Homopolymers or copolymers of vinyl ethers such as vinyl ethers such as methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone can be exemplified. As a typical binder resin, polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride is used. Examples thereof include copolymers, polyethylene and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin and waxes can be mentioned. Among these, it is particularly effective when polyester is used as the binder resin. For example, a linear polyester resin composed of a polycondensate containing bisphenol A and a polyvalent aromatic carboxylic acid as main monomer components can be preferably used.

Further, the softening point is 90 to 150 ° C., the glass transition point is 50 to 70 ° C., the number average molecular weight is 2000 to 6000,
Weight average molecular weight 8000 to 150,000, acid value 5 to 3
Resins having a hydroxyl value of 0 and a hydroxyl value of 5 to 40 can be particularly preferably used.

If desired, these toner particles may contain known additives such as a charge control agent and a fixing aid.

An image can be formed using the carrier and the developer described above, for example, using the apparatus shown in FIG. In this device, the lighting 801
The reflected light emitted from the original 802 from the color CCD 80
3 and read it by the image processing device 804.
The color separation is performed for each of the three colors and image processing is performed to output a signal from the semiconductor laser 805 for each color in order as a signal in which the angle of the closest pixel is changed. The optical signal is exposed through the optical system 806 to the photoconductor 808 that has been charged by the charger 807 in advance to form an electrostatic latent image in which the image portion has a low potential. Developers A, B composed of a charged colored toner obtained by the above method and a carrier,
By charging C and D in the developing devices 809 to 812 and applying a developing bias, the color toner is developed on the photoconductor by electrostatic force.

The developed toner is transferred to the sheet 814 electrostatically attracted to the transfer drum 813 one by one by the electric field given by the transfer corotron 815. This is Y,
By repeating M and C three times in this order, a color toner image in which three colors are overlaid on the transfer body is obtained. Then, heat fixing is performed by the fixing device 816 to obtain a color image.

[0066]

EXAMPLES Reference Example 1 Production of Carrier Reference Example 1 Carrier A Ferrite particles (average particle size; 50 μm) 100 parts by weight Toluene 14 parts by weight Styrene-methyl methacrylate copolymer (copolymer ratio 7: 3, weight average molecular weight) Mw: 50,000 critical surface tension 35 dyn / cm) 1.0 part by weight cross-linked benzoguanamine resin particles (critical surface tension 60 dyn / cm, average particle size; 0.5 μm, toluene insoluble) 0.2 parts by weight The above components excluding ferrite particles Is dispersed with a stirrer for 10 minutes to prepare a coating layer forming solution, and the coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then depressurized to toluene. Was distilled off to form a coating layer to obtain a carrier. Reference Example 2 Carrier B Ferrite particles (average particle size: 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymer ratio 4: 6, weight average molecular weight Mw: 50,000 critical surface) Tension 24 dyn / cm) 0.7 parts by weight crosslinked melamine resin particles (critical surface tension 65 dyn / cm, average particle size; 0.3 μm, toluene insoluble) 0.3 parts by weight Disperse the above components excluding ferrite particles with a stirrer for 10 minutes. Then, a coating layer forming liquid is prepared, and the coating layer forming liquid and ferrite particles are put into a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure is reduced to distill off toluene, A coating layer was formed to obtain a carrier. Comparative Reference Example 1 Carrier C A carrier was prepared in the same manner as in Example 1 except that the benzoguanamine resin particles were excluded. Comparative Reference Example 2 Carrier D Ferrite particles (average particle size; 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymer ratio 3: 7, weight average molecular weight Mw: 60,000 critical) Surface tension 24 dyn / cm) 0.5 parts by weight Copolymer of methyl methacrylate and dimethyl ethyl methacrylate (copolymer ratio 95: 5, weight average molecular weight Mw: 80,000 critical surface tension 42 dyn / cm) 0.3 parts by weight ferrite The above components except particles were dispersed by a stirrer for 10 minutes to prepare a coating layer forming liquid, and the coating layer forming liquid and ferrite particles were placed in a vacuum degassing type kneader and stirred at a temperature of 60 ° C for 30 minutes. Then, toluene was distilled off under reduced pressure to form a coating layer to obtain a carrier. Comparative Reference Example 3 Carrier E Ferrite particles (average particle size; 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymer ratio 4: 6, weight average molecular weight Mw: 60,000 critical) Surface tension 24 dyn / cm) 0.5 parts by weight uncrosslinked melamine resin (not in particle form) 0.3 parts by weight The above components except ferrite particles are dispersed with a stirrer for 10 minutes to prepare a coating layer forming liquid. The coating layer forming liquid and the ferrite particles were put in a vacuum degassing type kneader, stirred at a temperature of 60 ° C. for 30 minutes, and then depressurized to distill off toluene. Then, at a temperature of 150 ° C, 60
A carrier was obtained by forming a coating layer containing a crosslinked melamine resin by stirring for minutes. Comparative Reference Example 4 Carrier F Ferrite particles (average particle size; 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymer ratio 4: 6, weight average molecular weight Mw: 50,000 critical) Surface tension 24 dyn / cm) 0.6 parts by weight cross-linked methyl methacrylate resin particles (thermoplastic resin) (average particle size; 0.3 μm, swelling while insoluble in toluene) 0.3 parts by weight The above components except ferrite particles are used for 10 minutes. Disperse with a stirrer to prepare a coating layer forming liquid, and further put the coating layer forming liquid and ferrite particles in a vacuum degassing type kneader and stir at a temperature of 60 ° C for 60 minutes, then depressurize to distill off toluene. Then, a coating layer was formed to obtain a carrier. -Developer Preparation 1 Six kinds of developers were prepared by mixing 100 parts by weight of each of the carriers of Reference Examples 1 and 2 and Comparative Reference Examples 1 to 4 with 6 parts by weight of toner. Each developer is developer 1,
And 2及 beauty 3-6.

The toner used was 8 μm magenta toner (toner A) produced by the following method. Toner A linear polyester resin 100% by weight (linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol; Tg = 62 ° C., Mn = 4,000, Mw = 35,000, acid Value = 12, hydroxyl value = 25) Magenta pigment (CI Pigment Red 57) 3% by weight The above mixture is kneaded with an extruder, pulverized with a jet mill, and then dispersed with a wind classifier to obtain d50 = 8 μm
Magenta toner particles were obtained. Silica (trade name: R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the magenta toner particles with a 0.4 wt% Henschel mixer to obtain a magenta toner (toner A).・ Test and evaluation Electrophotographic copying machine (trade name:
A copy test was performed using A-Color 630, manufactured by Fuji Xerox Co., Ltd. The results are shown in Table 1.

[0068]

[Table 1]

In Table 1, the charge amount is a value obtained by CSG (charge spectrograph method) image analysis.
Fog is the result of visual observation of the copy (same in the table below).

◯ means no problem. × is a level that can be identified by comparing the white background with the white background on the copy.

XX is a level at which fog can be visually identified. In the copy test, medium temperature and humidity (22 ° C, 55% R
H) in an environment of 10.0 with these toner compositions
When 00 copies were made, the developers 1 and 2 were free from fluctuations in image density and background stains, and stable images were obtained. The initial charge amount, the amount of charge after 3000 sheets, and the amount of charge after 10.000 sheets were measured. However, with the developers 3 to 6, the charge amount was gradually decreased, and the background fog also appeared, and the toner stain inside the machine was also observed. -Developer preparation 2 Six kinds of developers were prepared by mixing 100 parts by weight of each of the carriers of Reference Examples 1 and 2 and Comparative Reference Examples 1 to 4 with 6 parts by weight of toner. Each developer is developer 7,
8,及 beauty 9 to 1 2.

The toner used is a 9 μm black toner (toner B) produced by the following manufacturing method. Toner B 100% by weight linear polyester resin (linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol; Tg = 62 ° C., Mn = 4,000, Mw = 35,000) , Acid value = 12, Hydroxyl acid value = 25) Carbon black (Mogal L; made by Cabot) 6% by weight The above mixture was kneaded with an extruder and pulverized with a volume pulverizer, and then with an air classifier. Fine particles and coarse particles were classified to obtain black toner particles having d ₅₀ = 9 μm. Silica (trade name: R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the black toner particles with a 0.4 wt% Henschel mixer to obtain a black toner (toner B).・ Test and evaluation Electrophotographic copying machine (trade name:
A copy test was performed using A-Color 630, manufactured by Fuji Xerox Co., Ltd. The results are shown in Table 2.

[0073]

[Table 2]

In the copy test, medium temperature and humidity (22 ° C,
Under the environment of 55% RH), 10.000 sheets were copied using these toner compositions.
In general, stable images were obtained without fluctuations in image density and background stains. The initial charge amount and after 3000 sheets, 10.00
The amount of charge after 0 sheets were measured. However, in the developers 9 to 12, the charge amount was gradually reduced, and the background fog was also generated, and the toner stain inside the machine was also observed. Reference Example 1A Production of Carrier Carrier AA Ferrite particles (average particle size; 50 μm) 100 parts by weight Toluene 14 parts by weight Styrene-methyl methacrylate copolymer (copolymer ratio 7: 3, weight average molecular weight Mw: 70,000 critical surface tension 35 dyn / cm) 1.2 parts by weight crosslinked benzoguanamine resin particles (critical surface tension 60 dyn / cm average particle size; 0.4 μm, toluene insoluble) 0.2 parts by weight The above components except ferrite particles are dispersed with a stirrer for 10 minutes, A coating layer forming liquid is prepared, and the coating layer forming liquid and ferrite particles are put in a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure is reduced to distill off toluene to form a coating layer. To form a carrier.

The film thickness of the resin coat obtained by calculation was 0.48 μm. Reference Example 2A Carrier BB Ferrite particles (average particle size; 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymer ratio 4: 6, weight average molecular weight Mw: 50,000 critical surface) Tension 24 dyn / cm) 1.0 part by weight crosslinked melamine resin particles (critical surface tension 65 dyn / cm average particle size; 0.3 μm, toluene insoluble) 0.3 parts by weight The above components except ferrite particles are dispersed with a stirrer for 10 minutes. A coating layer forming liquid was prepared, and the coating layer forming liquid and ferrite particles were put into a vacuum degassing type kneader, stirred at a temperature of 60 ° C. for 30 minutes, and then depressurized to distill off toluene to form a coating film. A layer was formed to obtain a carrier.

The film thickness of the resin coat obtained by the calculation was 0.36 μm. Comparative Reference Example 1A Carrier CC A carrier was prepared in the same manner as in Reference Example 1A except that the benzoguanamine resin particles were excluded. Reference Example 3A Carrier GG A carrier was prepared in the same manner as in Reference Example 1A, except that the amount of the styrene methacrylate copolymer was changed to 0.75 parts by weight.

The film thickness of the resin coat obtained by the calculation was 0.3 μm. Reference Example 4A Carrier HH A carrier was prepared in the same manner as in Reference Example 3A except that the crosslinked melamine resin particles having an average particle size of 0.3 μm were replaced with crosslinked melamine resin particles having an average particle size of 0.6 μm. -Developer Preparation 3 100 carriers each of Reference Examples 1A and 2A, Comparative Reference Example 1A, and Comparative Reference Examples 2 to 4 and Reference Examples 3A and 4A.
8 parts by weight of toner was mixed with 6 parts by weight of toner to prepare 8 kinds of developers. The respective developers are replaced with the developers 21 , 22 and 2
3-2 6, the same 27,2 8.

The toner used is the 8 μm magenta toner (toner A) produced by the above method.・ Test and evaluation Electrophotographic copying machine (trade name:
A copy test was performed using A-Color 630, manufactured by Fuji Xerox Co., Ltd. The results are shown in Table 3.

[0079]

[Table 3]

In the copy test, medium temperature and humidity (22 ° C,
Under the environment of (55% RH), 300.00 copies were made using these toner compositions.
In No. 22, stable images were obtained without fluctuations in image density and background stains. The initial charge amount and after 10.000 sheets, 3
The charge amount after 0.000 sheets were measured. However, developer 2
In Nos. 3 to 26, the electrification amount was gradually decreased, and after the printing of 10.000 sheets, the background fog also appeared, and the toner stain inside the machine was also observed.

With the developers 27 and 28, fog was not seen yet after 10.000 sheets and was good, but the electrification amount after 300.00 sheets was reduced and fog was observed. -Developer Preparation 4 Above Reference Examples 1A, 2A, Comparative Reference Example 2 and Reference Example 3
100 parts by weight of each of the carriers A and 4A is added to the toner 6
Six kinds of developers were prepared by mixing with parts by weight. The respective developers are referred to as developers 29 , 30 , 30 , 31 and 32 , 33.

The toner used is the 9 μm black toner (toner B) produced by the above-mentioned manufacturing method.・ Test and evaluation Electrophotographic copying machine (trade name:
A copy test was performed using A-Color 630, manufactured by Fuji Xerox Co., Ltd. The results are shown in Table 4.

[0083]

[Table 4]

In the copy test, medium temperature and humidity (22 ° C.,
Under the environment of (55% RH), 30.000 sheets were copied using these toner compositions.
In No. 30, stable images were obtained without fluctuations in image density and background stains. The initial charge amount and after 10.000 sheets, 3
The charge amount after 0.000 sheets were measured. However, developer 3
In No. 1, fog was observed after 10.000 sheets, background fog also appeared, and in-machine toner stain was also observed.

With the developers 32 and 33, the fog was not visible yet after 10.000 sheets, but the charge amount after 30.000 sheets was slightly decreased, and a little fog was observed. Reference example 1 B The above components except ferrite particles were dispersed with a stirrer for 10 minutes to prepare a coating layer forming liquid, and the coating layer forming liquid and ferrite particles were put into a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes. After that, the pressure was reduced and toluene was distilled off to form a coating layer to obtain a carrier. Reference example 2 B The above components except ferrite particles were dispersed with a stirrer for 10 minutes to prepare a coating layer forming liquid, and the coating layer forming liquid and ferrite particles were put into a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes. After that, the pressure was reduced and toluene was distilled off to form a coating layer to obtain a carrier. Example 1 The above components except ferrite particles were dispersed with a stirrer for 10 minutes to prepare a coating layer forming liquid, and the coating layer forming liquid and ferrite particles were put into a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes. After that, the pressure was reduced and toluene was distilled off to form a coating layer to obtain a carrier. Reference Example 3B Carrier DDD In the carrier BBB, the core particles have an average particle size of 60 μm.
Cu-having a shape factor SF1 of 125 and SF2 of 107 at m
A resin-coated carrier was obtained in the same manner except that the Mg ferrite particles were used instead. Reference Example 4B Carrier EEE In the carrier BBB, the core particles have an average particle size of 40 μm.
Cu-having a shape factor SF1 of 140 and SF2 of 115 at m
A resin-coated carrier was obtained in the same manner except that the Mg ferrite particles were used instead. Example 2 Carrier FFF In the carrier CCC, the core particles had an average particle size of 48 μm.
Cu-having a shape factor SF1 of 140 and SF2 of 115 at m
A resin-coated carrier was obtained in the same manner except that Zn ferrite particles were used instead. Comparative Example 1 Carrier GGG In the carrier CCC, the core particles have an average particle size of 35 μm.
Cu-having a shape factor SF1 of 147 and SF2 of 118 at m
A resin-coated carrier was obtained in the same manner except that Zn ferrite particles were used instead. Preparation of developer Using the toner A and the carriers AAA to GGG, 7 parts by weight of the toner A was added to 100 parts by weight of the carrier, mixed by a tumbler shaker mixer, and developed for evaluation. The agent was prepared. The respective developers are referred to as developers 41 to 46 and 47.

Toner B and carrier EEE to
Using GGG, 7 parts by weight of Toner B was added to 100 parts by weight of the carrier, and mixed with a tumbler shaker mixer to prepare a developer for evaluation. Each developer developer 48,4 9 was the same 5 0.・ Test and evaluation Electrophotographic copying machine (trade name:
A copy test was performed using A-Color 630, manufactured by Fuji Xerox Co., Ltd. The results are shown in Table 5.

[0087]

[Table 5]

The charge distribution is a value obtained by dividing the difference between the 20% charge amount Q (20) and the 80% charge amount Q (80) of the cumulative integration of the charge distribution by the 50% charge amount Q (50), that is, {Q (8
0) -Q (20)} / Q (50).

In the copy test, medium temperature and humidity (22 ° C,
55% RH) and using these developers,
0.000 copies were made. The charge amount and charge distribution were measured at the initial stage, after 5000 sheets, and after 20.000 sheets. The developers 43, 46 and 49 which are the preferred embodiments of the present invention are
In general, stable images were obtained without fluctuations in image density and background stains, and particularly good results were shown.

[0090]

As described in detail above, the carrier for developing an electrostatic latent image of the present invention is a carrier which can maintain good charging performance for a long period of time and has a long life, and moreover, due to the toner on the surface thereof. Spent can also be prevented in the long term. Therefore, a developer, an image forming method, and an image forming apparatus using the same can provide an electrophotographic image with good image quality for a long time.

[Brief description of drawings]

FIG. 1 is a schematic view showing one form of a carrier for developing an electrostatic latent image of the present invention.

FIG. 2 is a schematic view showing one form of an image forming apparatus of the present invention.

[Explanation of symbols]

1 career 20 Resin coating layer 21 Matricex Resin 22 Resin fine particles 30 core material A, B, C, D developer 809-812 developing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G03G 15/08 507L (72) Inventor Chiaki Suzuki 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Zerox Co., Ltd. (72) Inventor Suiko Sakai 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (56) Reference JP-A-1-105264 (JP, A) JP-A-6-118724 (JP, A) JP-A-6-308776 (JP, A) ) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 9/10 G03G 9/08

Claims (9)

(57) [Claims] 1. A matrix resin having a critical surface tension
Average primary particle size of 0.1 to 2 at 40 to 70 dyn / cm
A resin coating layer in which thermosetting resin fine particles containing nitrogen atoms of μm are dispersedly contained has a shape factor SF1 represented by the general formula (1) that satisfies the following formula (x) and is represented by the general formula (2). A carrier for an electrostatic latent image developer, which has a shape factor SF2 on a core material that satisfies the condition represented by the following formula (y). SF1 = (maximum length of diameter) ² / (area of carrier core material particles) × 100π / 4 (1) SF2 = (perimeter of projected image) ² / (area of carrier core material particles) × 100 / (4π) (2) 100 ≦ SF1 ≦ 145 (x) 100 ≦ SF2 ≦ 120 (y ) 2. The average thickness of the resin coating layer is 0.1 to 10
The carrier for an electrostatic latent image developer according to claim 1, wherein the carrier is μm. 3. The critical surface tension of the matrix resin is 35 dyn / cm or less.
The carrier for an electrostatic latent image developer according to item 1. 4. The carrier for an electrostatic latent image developer according to claim 1, wherein the average primary particle diameter of the carrier is 30 to 150 μm. 5. The electrostatic according to claim 1, wherein the average primary particle diameter (B) of the resin particles satisfies (B) ≦ (A) with respect to the resin coating layer thickness (A). Carrier for latent image developer. 6. A matrix resin having a critical surface tension
Average primary particle size of 0.1 to 2 at 40 to 70 dyn / cm
A resin coating layer in which thermosetting resin fine particles containing nitrogen atoms of μm are dispersedly contained has a shape factor SF1 represented by the general formula (1) that satisfies the following formula (x) and is represented by the general formula (2). An electrostatic latent image developer comprising a toner and a carrier for an electrostatic latent image developer having a shape factor SF2 on a core material that satisfies the condition represented by the following formula (y). SF1 = (maximum length of diameter) ² / (area of carrier core material particles) × 100π / 4 (1) SF2 = (perimeter of projected image) ² / (area of carrier core material particles) × 100 / (4π) (2) 100 ≦ SF1 ≦ 145 (x) 100 ≦ SF2 ≦ 120 (y ) 7. The electrostatic latent image developer according to claim 6 , which contains a linear polyester as a binder resin for the toner. 8. An image forming method of developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer containing a toner and a carrier on a developer carrier, the carrier comprising:
The matrix resin has a critical surface tension of 40 to 70 d.
Nitrogen atoms with an average primary particle size of 0.1 to 2 μm at yn / cm
The resin coating layer containing the thermosetting resin fine particles containing is dispersed so that the shape factor SF1 represented by the general formula (1) satisfies the following formula (x) and the shape factor SF2 represented by the general formula (2) is An image forming method characterized by using a carrier for an electrostatic latent image developer having on a core material that satisfies the condition represented by the following formula (y). SF1 = (maximum length of diameter) ² / (area of carrier core material particles) × 100π / 4 (1) SF2 = (perimeter of projected image) ² / (area of carrier core material particles) × 100 / (4π) (2) 100 ≦ SF1 ≦ 145 (x) 100 ≦ SF2 ≦ 120 (y ) 9. In an image forming apparatus for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer containing a toner and a carrier on the developer carrier, the carrier is a matrix. The resin has a critical surface tension of 40 to 70 dyn.
/ Cm containing a nitrogen atom having an average primary particle size of 0.1 to 2 μm.
The resin coating layer containing the thermosetting resin fine particles dispersed therein has the shape factor SF1 represented by the general formula (1) satisfying the following formula (x) and the shape factor S represented by the general formula (2).
An image forming apparatus, wherein F2 is a carrier for an electrostatic latent image developer having on a core material that satisfies the condition represented by the following formula (y). SF1 = (maximum length of diameter) ² / (area of carrier core material particles) × 100π / 4 (1) SF2 = (perimeter of projected image) ² / (area of carrier core material particles) × 100 / (4π) (2) 100 ≦ SF1 ≦ 145 (x) 100 ≦ SF2 ≦ 120 (y )