JP2000105490A - Electrostatic latent image developing carrier and image forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing carrier by which a stabilized electrification imparting characteristic is obtained over a long term and an image high in density and free from fogging is formed, and to provide an image forming device using the carrier. SOLUTION: In the electrostatic latent image developing carrier whose surface of a magnetic material particle is coated with a coating resin, the coating resin is a thermoplastic resin, and also the hardness of the coating resin is F to B by pencil hardness, and a coating quantity is 0.5-5.0 pts.wt. per magnetic material particle 100 pts.wt. In the image forming device including a process to develop an electrostatic latent image formed on an image carrier by two- component developer 40 consisting of a carrier and the toner, a process to transfer a toner image on the image carrier to a recording material and a process to clean the image carrier surface of the image carrier after transfer, the electrostatic latent image developing carrier is used as the carrier and a cleaning blade 62 is used as the cleaning means of the image carrier surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier for developing an electrostatic latent image, and more particularly to a carrier for developing an electrostatic latent image which can be used for a long time and is coated with a thermoplastic resin having a stable charge-providing ability. It is about.

[0002] The present invention also relates to an image forming apparatus using a two-component developer as a developer, and more particularly to an image forming apparatus using the carrier for developing an electrostatic latent image.

[0003]

2. Description of the Related Art In electrophotography, a magnetic brush developing method has conventionally been widely used for developing an electrostatic latent image, and a two-component developing method comprising a mixture of a magnetic carrier and a toner is used as a developer for this. Agents are widely used.

As a problem of the two-component developer, there is a so-called spent toner in which a toner component is fused to a carrier surface. As a result, it is known that the charge imparting ability of the carrier is reduced, the image density is reduced, and fogging occurs. The spent toner is a phenomenon in which a toner component adheres and deposits on the surface of a magnetic carrier in a film form. Since the surface of the magnetic carrier becomes close to the toner component, the frictional charge train approaches and a predetermined charge is obtained. Performance will not be obtained. Therefore, when spent toner is generated, there is a disadvantage that the magnetic carrier must be discarded and replaced with a new magnetic carrier.

[0005] To solve this problem, resin-coated carriers in which the surface of carrier particles is coated with various resins have been proposed. For example, it has been proposed to use a fluororesin from the viewpoint of surface contamination resistance. Further, Japanese Patent Application Laid-Open No. 8-31
In Japanese Patent No. 4198, in order to prevent adhesion of toner and the like,
Specific weight average molecular weight (Mw), number average molecular weight (Mn)
It has been proposed to use a polyolefin having the above as a coating resin, and has a certain effect in preventing adhesion of toner components and the like.

However, in the former method, since fluorine itself has a strong negative chargeability, the ability to charge the toner to a negative polarity is low, and the use is limited. Further, the latter method has not been able to sufficiently satisfy the developing characteristics after long-term use.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the prior art, to obtain a stable charging property for a long period of time, and to form a high-density, fog-free image. To provide a carrier for

It is another object of the present invention to provide an image forming apparatus using the carrier.

[0009]

According to the present invention, in a carrier for developing an electrostatic latent image in which the surface of magnetic particles is coated with a coating resin, the coating resin is a thermoplastic resin, and The hardness of the coating resin is F ~
B, wherein the coating amount is from 0.5 to 5 parts by weight based on 100 parts by weight of the magnetic particles.

In the present invention, the absolute value of the saturation charge between the magnetic particles and the toner is X (μC / g), and the absolute value of the saturation charge between the electrostatic latent image developing carrier and the toner is Y.
(ΜC / g), it is preferable to satisfy the following expression (1). (Y + 2) ≦ X ≦ (Y + 10) (1)

In the present invention, the coating resin further has a chargeability and / or particle size of 0.005 to 1 micron.
Or 0.1 to 100 parts by weight of the conductive particles to the resin
It is preferred to contain 10 parts by weight.

Further, according to the present invention, a step of developing an electrostatic latent image formed on an image carrier with a two-component developer composed of a carrier and a toner is provided. In the image forming apparatus including the step of transferring to the image carrier, the step of cleaning the image bearing surface of the image carrier after the transfer, as a carrier, a carrier in which the surface of the magnetic particles is coated with a coating resin, wherein the coating resin is A thermoplastic resin, and the hardness of the coating resin is a pencil scratch value of FB,
The resin coating amount is 0.5 to 100 parts by weight of the magnetic particles.
An image forming apparatus is provided in which a carrier for developing an electrostatic latent image, which is 5 parts by weight, is used, and a cleaning blade is used as a means for cleaning an image carrier surface.

At this time, the absolute value of the saturation charge between the magnetic particles and the toner is X (μC / g), and the absolute value of the saturation charge between the electrostatic latent image developing carrier and the toner is Y (μC / g).
/ G), it is preferable that the carrier for developing an electrostatic latent image satisfies the expression (1). The carrier for developing an electrostatic latent image has a particle size of 0.005 to 0.005 in the coating resin.
It is preferable to contain 0.1 to 10 parts by weight of 1 micron chargeable or conductive particles based on 100 parts by weight of the resin. Further, it is desirable that the image bearing member is a photosensitive member provided with a photosensitive layer made of amorphous silicon.

[0014]

The carrier for developing an electrostatic latent image according to claim 1, wherein the surface of the magnetic particles is coated with a coating resin.
The "carrier" may be noted) is a remarkable feature that the coating resin is a thermoplastic resin, and the hardness of the coating resin is F to B in pencil scratch value,
As a result, stable charging characteristics can be obtained over a long period of time, and an image having a high density and no fog can be formed.

Conventionally, the main focus has been to prevent toner spent from adhering to the carrier surface. However, in the present invention, it is inevitable that the toner spent is adhered to the carrier surface to some extent. So that the resin on the carrier surface can be peeled off
A new resin surface to which no toner spent adhered appeared on the carrier surface.

In order for the coated resin to peel off in sequence, it is necessary to use a thermoplastic resin as the coating resin. In the case of a thermosetting resin, the resin becomes too hard, so that the resin hardly peels off. It is also necessary that the hardness of the resin for coating is in the range of FB in pencil scratch value. When the pencil scratch value is harder than F, peeling of the resin is less likely to occur and a new coated surface is less likely to appear on the carrier surface. On the other hand, if the pencil scratching value is softer than B, the peeling of the resin proceeds excessively, and the carrier cannot be used for a long time.

The pencil scratch value in the present invention is
Test plate (steel plate 150mm × 70mm × 0.8mm)
After uniformly applying a toluene solution of the resin to be measured with a brush, the oven (“PERFECTOVERS-21”) was used.
2) manufactured by Tabai Espec Co., Ltd.), dried and cured at 100 ° C. for 1 hour at 100 ° C. for thermoplastic resin and 1 hour at the curing temperature of the thermosetting resin at JIS. It is a value measured by the handwriting method specified in the standard (K5400-1990).

The carrier for developing an electrostatic latent image of the present invention also has a resin coating amount of 0.5 to 5 parts by weight per 100 parts by weight of the magnetic particles. When the resin coating amount is less than 0.5 part by weight, the entire surface of the magnetic particles cannot be coated with the coating resin, or even if the coating can be performed, the resin layer thickness is small and the carrier cannot withstand long-term use. Become. The other 5
When the amount exceeds the weight part, there are problems that the carrier is aggregated and the magnetic particles cannot be uniformly coated with the resin.

In the carrier for developing an electrostatic latent image according to the present invention, the absolute value of the saturation charge between the magnetic particles and the toner is X, and the absolute value of the saturation charge between the carrier for the electrostatic latent image and the toner is X. When the value is Y, it is necessary to further satisfy the expression (1). In other words, by making the charge-imparting ability of the magnetic particles higher than that of the carrier coated with the coating resin, the peeling of the coated resin proceeds by use, the layer thickness of the resin becomes thinner, and eventually Even if the resin disappears and the surface of the magnetic particles is partially exposed, the ability to impart charge to the toner can be maintained, and the use period of the carrier can be further extended.

When the saturation charge amount X between the magnetic particles and the toner is smaller than the lower limit of the above formula (1), the charging ability of the magnetic particles is not sufficient, and the use period of the carrier may be sufficiently extended. Can not. On the other hand, when the saturated charge amount X is larger than the upper limit of the formula (1), the charge-imparting ability of the magnetic particles becomes too large, and the toner becomes overcharged, which may cause a decrease in image density.

Further, in the carrier for developing an electrostatic latent image according to the third aspect, the coating resin contains chargeable and / or conductive particles having a particle size of 0.005 to 1 micron with respect to 100 parts by weight of the resin. 0.1 to 10 parts by weight. That is, since the chargeable and / or conductive particles are contained in the coating resin, the control of the charge application to the toner becomes easy, and the peeling of the resin proceeds smoothly, so that the charge application of the carrier is performed. Ability can be maintained for a long time.

If the particle size of the particles is smaller than 0.005 micron, the effect of promoting the peeling of the resin is not exhibited. May not be usable.

If the content of the particles is less than 0.1 part by weight, the charging control cannot be sufficiently performed, and if the content is more than 10 parts by weight, the peeling of the resin is promoted and the carrier is used for a long time. May not be possible.

According to a fourth aspect of the present invention, there is provided the image forming apparatus, wherein the carrier for developing an electrostatic latent image is used in which the surface of magnetic particles is coated with a specific coating resin, and a cleaning blade is used as a means for cleaning the surface of the image carrier. It is a great feature to use. By using the above-mentioned carrier, stable charging characteristics can be obtained over a long period of time, and an image without fogging can be formed at a high density.On the other hand, the coating resin acts as a charging agent for the toner. Therefore, a material that is inevitably charged to the opposite polarity to the toner is used. For this reason, especially when the developing method is the reversal development, the coating resin peeled off from the carrier surface (sometimes referred to as “coated resin piece”) is mixed into the developer, and the non-latent May move and adhere to the image area. Most of the coated resin pieces adhered to the image carrier are charged to the opposite polarity to the toner, and therefore do not move to the transfer material in the transfer process and remain on the image carrier. Generally, an image forming apparatus is provided with cleaning means for cleaning untransferred toner and the like on an image carrier, but these cleaning means are mainly used for collecting untransferred toner and paper dust. Therefore, some conventional cleaning means cannot sufficiently collect the coated resin pieces. Therefore, the present inventors have conducted intensive studies on means suitable for cleaning the coated resin pieces on the image carrier, and as a result, it has been found that the cleaning means using the cleaning blade is most suitable for cleaning the coated resin pieces. And found the present invention.

The image forming apparatus according to the present invention will be described with reference to FIG. 1. A photosensitive member 1 using a photosensitive member 1 as an image carrier and having a surface uniformly charged to a positive polarity by a charging device 2 is:
The exposure device 3 forms an electrostatic latent image. In the developing device 4, toner is adhered to the electrostatic latent image by a magnetic brush of a developer 42 formed of toner and the carrier formed on a developing roller 41 having a magnet therein, and is visualized. In the transfer device 5, the toner image on the photoconductor is transferred to a transfer material. The transfer material on which the toner image has been transferred is
Thereafter, in a fixing unit (not shown), the image is fused and fixed on the transfer material by heat and pressure. On the other hand, the untransferred toner and coated resin pieces remain on the photoreceptor. The remaining toner and the coated resin pieces are cleaned in advance by the cleaning brush 61 in the cleaning device 6 and then completely cleaned by the cleaning blade 62.

As the image bearing member used in the present invention, a photosensitive member having a photosensitive layer made of amorphous silicon is preferable.
This is because such a photoconductor has a high surface hardness, so that the contact pressure of the cleaning blade with respect to the photoconductor can be increased, and the coated resin piece remaining on the photoconductor can be more reliably cleaned. Further, the photoreceptor has high sensitivity over the entire visible light range and is excellent in heat resistance and the like.

(Coating Resin) The coating resin used in the present invention is not particularly limited as long as it is a thermoplastic resin. Examples thereof include polyethylene, polypropylene, polyvinyl chloride, poly-4-methylpentene-1, and poly (4-methylpentene). Vinylidene chloride, ABS (acrylonitrile-butadiene-styrene) resin, polystyrene, (meth) acrylic resin, polyvinyl alcohol resin, and thermoplastic elastomer such as polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, etc. Is mentioned.

Of these thermoplastic resins, (meth) acrylic resins are more preferred. Specifically, a resin mainly composed of an acrylic ester or a methacrylic ester and copolymerized with an unsaturated monomer represented by the following general formula (2) is preferably used.

[0029]

Embedded image

(Wherein, R ¹ represents a hydrogen atom, a methyl group or an ethyl group, and Z represents a hydrocarbon group having 4 or more carbon atoms).

Examples of the esters of acrylic acid and the esters of methacrylic acid include methyl (meth) acrylate,
Ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2- Ethylhexyl (meth)
Acrylate, n-octyl (meth) acrylate and the like can be used. Note that (meth) acrylic acid refers to acrylic acid or methacrylic acid.

In the above formula of the unsaturated monomer, the substituent represented by Z is an alicyclic hydrocarbon group having 4 or more carbon atoms such as a cyclohexyl group, a methylcyclohexyl group, a cyclododecyl group; a butyl group, an isobutyl group Tert-butyl group, 2
-A linear or branched alkyl group having 4 or more carbon atoms such as an ethylhexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a pentadecyl group, an octadecyl group; a carbon atom of a bornyl group or an isobornyl group It is a polycyclic hydrocarbon group having a number of 4 or more, and among them, an alicyclic hydrocarbon group, a branched alkyl group, and a straight-chain alkyl group having 6 or more carbon atoms are preferable.

Examples of the unsaturated monomer represented by the general formula (2) include, for example, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, isobutyl (Meth) acrylate, tert-butyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like, and one or more of these. Can be used.

The hardness of the resin can be controlled by the type and blending amount of the monomer used, the molecular weight of the resin, and the like, and is represented by the general formula (2) together with the (meth) acrylic resin listed as a preferred resin. Taking a copolymer with an unsaturated monomer as an example, the resin is hardened by a (meth) acrylic resin, and the resin is brittle by an unsaturated monomer represented by the general formula (2). Therefore, the desired hardness can be obtained by adjusting the mixing ratio of the monomers.

(Magnetic Particles) The material of the magnetic particles that can be used in the present invention is not particularly limited, but magnetic metals such as iron, nickel and cobalt and alloys thereof, alloys containing rare earth elements, hematite , Magnetite, manganese-zinc ferrite, nickel-zinc ferrite, manganese-magnesium ferrite, soft ferrite such as lithium ferrite, iron-based oxides such as copper-zinc ferrite, and mixtures thereof. The magnetic particles used in the present invention can be produced by using the above materials by a production method such as a sintering method and an atomizing method.

Further, a magnetic material-dispersed resin can be used as the magnetic material particles. As the magnetic material to be used, the above magnetic material can be used, and as the binder resin, for example, a vinyl resin, a polyester resin, an epoxy resin, a phenol resin, a urea resin, a polyurethane resin, a polyimide resin, a cellulose resin, a polyether resin or These mixtures can be mentioned.

The particle diameter of the magnetic particles is generally in the range of 30 to 200 microns, particularly preferably in the range of 50 to 150 microns as represented by the particle diameter measured by electron microscopy. In the case of the above, although it differs depending on the composition and surface structure of the magnetic material, it is generally 2.0 to 2.0.
The range is preferably 3.0 g / cm ³ . Further, the saturation magnetization of the magnetic particles is preferably in the range of 40 to 70 Am ² / kg.

(Resin coating) In the present invention, in order to coat the surface of the magnetic particles with the coating resin, a solution or dispersion of the coating resin may be applied to the magnetic particles. Examples of the solvent for the coating solution include aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; ethanol, propanol and butanol Alcohol solvents such as ethyl cellosolve, butyl cellosolve and the like; ester solvents such as ethyl acetate and butyl acetate; and one or more kinds of amide solvents such as dimethylformamide and dimethylacetamide. . The resin component concentration in the coating solution is generally 0.001.
It is preferably in the range of 〜30 wt%, particularly 0.001 to 2 wt%.

As a method of applying the coating resin to the magnetic particles, for example, a spray drying method, a fluidized bed method, a spray drying method using a fluidized bed, an immersion method and the like can be used. Among these, the fluidized bed method is particularly preferred in that the coating can be performed efficiently with a small amount of coating resin. The resin coating amount can be adjusted by, for example, the amount of the resin solution to be sprayed or the spraying time in the case of the fluidized bed method.

According to the second aspect of the invention, the saturation charge amount of the magnetic particles depends on the chemical composition, the particle size, the particle shape, and the surface condition of the magnetic particles. On the other hand, the saturation charge of the carrier is dependent on the above-described saturation charge of the magnetic particles,
It also depends on the chemical composition of the coating resin, the physical properties including the tendency to triboelectric charging, the coating amount, and the like. By selecting and combining these factors, it is possible to obtain a carrier for developing an electrostatic latent image that satisfies the relationship of the above formula (1).

The saturated charge amount of the carrier and the toner coated with the coating resin is generally expressed as an absolute value and is generally 5 to 35 μC /
g, especially in the range of 10 to 30 μC / g. The electric resistance of the carrier may be either high resistance or low resistance, and is generally 2 × 10 ⁵ to 2 × 10 ¹⁵ Ω ·
cm, particularly preferably 2 × 10 ⁷ to 2 × 10 ¹³ Ω · cm.

In the present application, the saturation charge amount was measured using a suction-separation type charge measuring device manufactured by Sankyo Piotech. FIG. 2 schematically shows the measuring apparatus. The measuring device includes a main body measuring unit 7, a main body control unit 8, a charge meter 9, a balance 10, and a suction pump 11. Main body measurement section 7
3 is shown in FIG. The specific measurement procedure is as follows. First, a 400 mesh wire net 72 is attached to two places above and below the Faraday gauge 71, and the mass of the empty Faraday gauge 71 is measured. The mesh wire net 72 is replaced every ten measurements. Next, a measurement sample composed of the carrier and the toner is weighed by a 0.50 ± 0.10 g balance 10 and put into a Faraday gauge 71 attached to the main body measurement unit. Suction pressure 2.0 × 10 ³ ± 0.1 × 10 ³ Pa, suction time 60 sec
The suction from the Faraday gauge 71 is started at c, and the maximum charge amount within the suction time is measured by the charge meter. After the measurement, the mass of the Faraday gauge 71 is measured, and the mass of the measured Faraday gauge 71 is subtracted from the mass of the Faraday gauge 71 in which the measurement sample is initially placed, to thereby convert the mass of the sucked toner. From the above measurement results, the charge amount of the carrier is calculated by the following equation. Carrier charge (μC / g) = measured charge / toner mass

Here, as the standard toner used in the main measurement, a toner prepared as follows is used. That is, aliphatic alcohol-based polyester resin (ethylene glycol 20.1 mol%, neopentyl glycol 27.5 mol%, terephthalic acid 40.2
mol%, 1,2,4-benzenetricarboxylic anhydride 1
2.2 mol%) and an aromatic polyester resin (48.6 mol% of polyoxypropylene- (2,2) -2-bis (4-hydroxyphenyl) propane, 49.6 mol% of terephthalic acid): 100 parts of a resin mixed at a ratio of 25, "Raven 1
After melting and kneading 8.0 parts of “255” and 5.0 parts of “carnauba wax” as a wax, the mixture is pulverized and classified to obtain toner particles having an average particle size of 9.0 μm. 0.9 parts of "BL220W" manufactured by Titanium Industry Co., Ltd., and hydrophobic silica ("R812S" manufactured by Nippon Aerosil Co., Ltd.) are added, and a toner obtained by high-speed stirring and mixing with a Henschel mixer is used as a standard toner.

According to the third aspect of the present invention, in order to include the charged and / or conductive particles having a predetermined particle size in the coating resin, the particles are added to a solution or dispersion of the coating resin. The solution or dispersion may be applied to the magnetic particles. Alternatively, after coating and drying the coating resin on the surface of the magnetic particles, the particles may be attached to the resin and embedded in the resin by a mechanical impact force.

The chargeable particles usable in the present invention include:
For example, metal oxides such as silica, chromium oxide, iron oxide, manganese oxide, molybdenum oxide, titanium oxide, tungsten oxide, vanadium oxide, aluminum oxide, magnesium oxide, silane oxide, zirconia oxide; salicylic acid derivatives, azo-based metal complexes, etc. Dyes include organic salts such as quaternary ammonium salts.

Examples of the conductive particles include carbon black such as acetylene black and furnace black.
Examples thereof include carbides such as silane carbide, titanium carbide, and zirconia carbide, boron nitride, neodymium nitride, titanium nitride, and zirconia nitride.

(Two-Component Developer) The carrier for developing an electrostatic latent image of the present invention can be used in combination with a toner known per se.
Used as a two-component developer for developing electrostatic latent images. The toner for a two-component developer is obtained by dispersing a colorant, a charge control agent, a release agent, and the like in a binder resin, granulating the resultant, and externally adding a fluidity improver as desired.

As the toner used in combination with the carrier for developing an electrostatic latent image according to the present invention, a toner not containing a charge controlling agent, which is a main cause of spent toner (“CC
A-less toner) is preferable from the viewpoint of extending the life of the carrier.

As the binder resin which is a toner component, a thermoplastic resin or a thermosetting resin which is uncured or an initial condensate is used. For example, a vinyl aromatic resin such as polystyrene, a styrene-acryl copolymer, an acrylic resin, a polyvinyl acetal resin, a polyester resin, an epoxy resin, and a phenol resin are used.

In order to control the charge amount of the toner, a charge control agent is generally used. Nigrosine bases, quaternary ammonium salts, and the like can be used as the positively chargeable charge control agents, and metal complex salt dyes, salicylic acid derivatives, sulfonic acid derivatives, and the like can be used as the negatively chargeable charge control agents. On the other hand, in the case of the CCA-less toner, since the charge control agent is not used, it is necessary to cause the binder resin to perform a part of the charge control action. Therefore, it is necessary to use a copolymer or a resin composition having an anionic or cationic polar group as a part of the toner binder resin. Examples of the cationic polar group include a basic nitrogen-containing group such as a primary, secondary or tertiary amino group, a quaternary ammonium group, an amide group, an imino group, an imide group, a hydrazino group, a guanidino group, and an amidino group. However, examples of the anionic polar group include any polar group such as carboxylic acid, sulfonic acid, and phosphonic acid. Examples of the resin include a resin obtained by polymerizing a cationic or anionic polar group-containing monomer with another monomer or resin by means of random copolymerization, block copolymerization, graft copolymerization, or the like.

Examples of the coloring agent contained in the resin include carbon blacks such as acetylene black, lamp black and aniline black as black pigments; and graphite, zinc yellow, cadmium yellow, yellow iron oxide, and minerals as yellow pigments. Fast Yellow, Nickel Titanium Yellow, Navels Yellow, Naphthol Yellow S, Hanza Yellow G, Hanza Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake; Lead, molybdenum orange, permanent orange GTR, pyrazolone orange, balkan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK As red pigments, red pigment, cadmium red, lead red, mercury cadmium sulfide, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, Brilliant Carmine 3
B; purple pigments, manganese purple, fast violet B, methyl violet lake; blue pigments, navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue,
First Sky Blue, Induslen Blue BC; green pigments: chrome green, chromium oxide, pigment green B, malachite green lake, fanal yellow green G; white pigments: zinc white, titanium oxide, antimony white, zinc sulfide; white As the pigment, barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white and the like can be used. The pigment is used in an amount of 2 to 20 parts by weight, particularly 5 to 15 parts by weight, per 100 parts by weight of the binder resin.

Various waxes and low molecular weight olefin resins can be contained in the binder resin as a releasing agent for heat fixing. The olefin resin has a number average molecular weight (Mn) of 1,000 to 1,000. 10,000 range, especially 2,
Those in the range of 000 to 6,000 are preferred. As the olefin-based resin, polypropylene, polyethylene, and a propylene-ethylene copolymer are used, and polypropylene is particularly preferable.

In the case of the CCA-less toner, it is preferable that a magnetic powder be further contained in order to suppress toner scattering due to insufficient charge amount. The content of the magnetic powder is in the range of 0.1 to 5 parts by weight, particularly 0.5 to 3.0 parts by weight, per 100 parts by weight of the binder resin.
A small amount of internal addition such as in the range of parts by weight is sufficient.

The magnetic powder to be used is a conventional magnetic toner.
Magnetic powders used for iron, such as triiron tetroxide (Fe_Three
O_Four), Iron sesquioxide (γ-Fe_TwoO_Three), Zinc iron oxide (Z
nFe _ThreeO_Four), Yttrium iron oxide (Y_ThreeFe_FiveO₁₂),
Cadmium iron oxide (CdFe_TwoO_Four), Gadolinium iron oxide
(Gd_ThreeFe_FiveO₁₂), Copper iron oxide (CuFe_TwoO_Four), Oxidation
Iron lead (PbFe₁₂O₁₉), Nickel iron oxide (NiFe_Two
O_Four), Neodymium iron oxide (NdFeO)_Three), Iron oxide burr
Um (BaFe₁₂O₁₉), Magnesium iron oxide (MgF
e_TwoO_Four), Iron manganese oxide (MnFe)_TwoO_Four),iron oxide
Lantern (LaFeO_Three), Iron powder (Fe), cobalt powder
(Co), nickel powder (Ni), etc.
You. A particularly preferred magnetic powder is fine iron tetroxide (magneta
It). The preferred magnetite is octahedral
The diameter is 0.05 to 1 μm. This magnety
Particles are silane coupling agent, titanium-based
May be surface-treated with a rubbing agent or the like.

(Production Method of Toner)
Although it can be produced by a method known per se, such as a melt granulation method, a spray granulation method, and a polymerization method, a pulverization classification method is generally used. Each of the toner components is pre-mixed with a mixer such as a Henschel mixer, and then kneaded using a kneading device such as a twin-screw extruder. After cooling the kneaded composition, pulverize and classify to obtain a toner. .

The particle diameter of the toner is generally 5 to 15 μm, particularly 7 to 12 μm, as measured by a Coulter counter.
m.

If necessary, a fluidity improver such as hydrophobic fumed silica may be externally added to the surface of the toner particles to improve the fluidity of the toner. The amount of the fluidity improver is preferably 0.1 to 2.0% by weight per toner.

At this time, the transfer efficiency may be improved by incorporating spacer particles having a particle size of 0.05 to 1 μm, which are larger in particle size than the flow improver, in the flow improver.

As the spacer particles, any organic or inorganic inert fixed particles having the above particle size can be used. In general, the above-mentioned magnetic powder, particularly, fine iron tetroxide (magnetite) ) Is preferred. This is because the magnetic powder adhering to the surface of the toner particles effectively acts on toner scattering.

Spacer particles such as fine iron sesquioxide (magnetite) are preferably externally added in an amount of 0.1 to 10% by weight per toner.

When the fluidity improver and the spacer particles are externally added to the toner, it is preferred that the fluidity improver and the spacer particles be mixed intimately in advance, and that this mixture be added to the toner and sufficiently mixed.

(Cleaning Blade) As the material of the cleaning blade used in the present invention, estramers such as urethane rubber and silicone rubber and foams thereof are preferable. In particular, silicone rubber is less deteriorated with time and can maintain good characteristics.

The blade contacting method may be either a leading method or a trailing method, and the contact angle to the image carrier varies depending on these methods. Among these methods, the leading method, in which the combined force of the pressing force and the frictional force acts in the direction of compressing the elastic rubber blade, has a high cleaning force and works effectively with a relatively small pressing force. It is suitable for cleaning coated resin pieces having a diameter.

For the purpose of protecting the image carrier and reducing the creep of the cleaning blade, a separation / contact mechanism for releasing pressure contact of the blade at rest, and a pre-cleaning roller for preventing poor cleaning due to the presence of a coating resin piece or the like. Or a thrust mechanism that moves the cleaning blade in the axial direction of the image carrier, or a scraper blade that removes a residue such as a coated resin piece adhered to the edge of the cleaning blade for every fixed number of copies. May be appropriately used in combination.

The pressure contact condition of the cleaning blade may be appropriately set according to the material and properties of the image carrier, the properties of the toner and the coated resin pieces, the temperature inside the apparatus, and the like. For example, when describing the pressure contact conditions for the leading method, the hardness of rubber is 55
~ 80 °, the contact angle between the blade and the image carrier is 15 ~ 3
0 ° and the solid line pressure are preferably in the range of 5 to 15 g / cm.

(Image Carrier) The image carrier used in the present invention has a photosensitive layer on its surface. As a photoconductor material contained in the photoconductor layer, an amorphous chalcogenide material containing amorphous selenium and its alloy; a group II-IV inorganic compound material such as zinc oxide and cadmium sulfide; Organic photoconductor materials including resin-dispersed composite systems of organic compounds; amorphous silicon-based materials can be used. Among them, an image carrier having a photosensitive layer made of amorphous silicon and having a high surface hardness is preferable because the cleaning blade can be strongly pressed. Amorphous silicon includes amorphous silicon, amorphous silicon germanium, amorphous silicon nitride, a material in which part of hydrogen is replaced with fluorine, and the like.

The shape of the image carrier used in the present invention may be a sheet shape, a belt shape, a web shape, or a drum shape, but is preferably a belt shape or a drum shape in terms of speeding up and miniaturization.

[0068]

EXAMPLE 1 3 kg of manganese-zinc ferrite magnetic particles having an average particle diameter of 70 μm, a saturation magnetization of 60 Am ² / kg, and an electric resistance of 5 × 10 ⁸ Ω · cm were coated with a coating apparatus (“SPIR-A-
FLOW "MINI" manufactured by Freund Corporation)
The apparatus was started up to a fluid state. On the other hand, magnetic particles 1
2 parts by weight of a thermoplastic copolymer resin of methyl methacrylate and its derivative (weight molecular weight of 10,000 to
000) was dissolved in toluene, and this resin solution was supplied to the coating apparatus, and the surface of the magnetic particles was coated with the coating resin by spraying. The coated carrier was dried in a fluidized state continuously at 40 ° C. for 1 hour. On the other hand, when the coating resin solution was dried and its hardness was measured by the above-mentioned measuring method, the hardness was F. The coated carrier was mixed with the standard toner, and a blade hardness of 62 °
Using the image forming apparatus shown in FIG. 1, which is a cleaning blade characteristic and a mounting condition of a solid line pressure of 8.8 g / cm and a pressure contact angle of 18.63 °, a carrier life is determined by the following measurement method / standard.
The image, physical properties and cleaning performance were measured. The results are shown in Table 1.

(Carrier Life) The developer consisting of the coated carrier and the standard toner was put into the developing device of the above-mentioned copying machine, and the stirring was continuously driven.

(Measurement of Image Density "ID") Using a reflection densitometer (Model TC-6D, manufactured by Tokyo Denshoku Co., Ltd.), the density of the black solid portion of the copied image was measured.

(Measurement of Fog Density “FD”) The density of a blank portion of a copied image was measured using the reflection densitometer, and the fog density was determined.

(T / D) The developer is collected from the surface of the developing sleeve, and its weight is measured first. Next, the toner is suction-separated from the developer, the weight of the toner is obtained, and the toner weight ratio per developer weight is calculated.

(Charge Amount) The developer was sampled from the surface of the developing sleeve and measured using a suction-separation type charge measuring device manufactured by Sankyo Piotech.

(Spent amount) After printing, the carrier alone was separated from the developer, and the difference between the carbon content measured by a “carbon analyzer” and the initial carbon content of the carrier was determined. The weight ratio of the attached toner composition was calculated.

(Cleaning Performance) The cleaning performance was evaluated based on the following criteria based on the presence or absence of image contamination. ×: Image stains generated ○: No image stains (cleaning blade life is 20
◎: No image contamination (life of cleaning blade is 40)
10,000)

Example 2 The characteristics and mounting conditions of the cleaning blade were changed to a hardness of 72.
And cleaning performance was observed in the same manner as in Example 1 except that the solid line pressure was changed to 10.5 g / cm. Table 1 shows the results.

Example 3 The characteristics and mounting conditions of the cleaning blade were
And cleaning performance was observed in the same manner as in Example 1 except that the solid line pressure was 8.9 g / cm. Table 1 shows the results.

Example 4 The characteristics and mounting conditions of the cleaning blade were changed to a hardness of 71.
And cleaning performance was observed in the same manner as in Example 1 except that the solid line pressure was changed to 10.4 g / cm. Table 1 shows the results.

Example 5 A coated carrier was prepared in the same manner as in Example 1 except that a thermoplastic copolymer resin comprising methyl methacrylate having a weight molecular weight of 25,000 to 30,000 and a derivative thereof was used. This coating resin solution was dried, and its hardness was measured by the above-mentioned measuring method.
The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 6 A resin for coating was prepared by dissolving 0.5 part of a thermoplastic copolymer resin of methyl methacrylate and its derivative (weight-average molecular weight: 10,000 to 20,000) in 100 parts of magnetic particles in toluene. A coated carrier was prepared in the same manner as in Example 1 except that a solution was prepared. The resin solution for coating was dried, and the hardness was measured by the above measuring method.
Met. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 7 Five parts of a thermoplastic copolymer resin of methyl methacrylate and its derivative (weight molecular weight: 1
(0000 to 20,000) was dissolved in toluene to prepare a coating resin solution, and a coated carrier was prepared in the same manner as in Example 1. The resin solution for coating was dried, and the hardness was measured by the above measuring method.
Met. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 8 In a coating resin solution, 0.1 part was added to 100 parts of the magnetic particles.
A coated carrier was prepared in the same manner as in Example 1, except that aluminum oxide (particle size: 0.02 μm) was dispersed in some parts. The resin solution for coating was dried, and the hardness was F as measured by the above-mentioned measuring method. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 9 A coated carrier was prepared in the same manner as in Example 1 except that 10 parts of aluminum oxide (particle size: 0.02 μm) was dispersed in 100 parts of magnetic particles in the resin solution for coating. did. The resin solution for coating was dried, and the hardness was F as measured by the above-mentioned measuring method. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 10 A coated carrier was prepared in the same manner as in Example 1 except that 5 parts of aluminum oxide (particle diameter: 0.005 μm) was dispersed in 100 parts of magnetic particles in the resin solution for coating. did. The resin solution for coating was dried, and the hardness was F as measured by the above-mentioned measuring method. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 11 Except that 5 parts of aluminum oxide (particle size: 1 μm) was dispersed in 100 parts of magnetic particles in a coating resin solution.
A coated carrier was produced in the same manner as in Example 1. The resin solution for coating was dried, and the hardness was F as measured by the above-mentioned measuring method. In this coated carrier,
The standard toner was mixed, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 12 A coated carrier was prepared in the same manner as in Example 1 except that 5 parts of aluminum oxide (particle size: 0.02 μm) was dispersed in 100 parts of magnetic particles in the resin solution for coating. did.
The resin solution for coating was dried, and the hardness was F as measured by the above-mentioned measuring method. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Example 13 A coated carrier was prepared in the same manner as in Example 1 except that a magnetic material of manganese-zinc-based ferrite having an electric resistance of 1.6 × 10 ⁸ Ωcm was used. Table 1 shows the results.

Example 14 A coated carrier was prepared in the same manner as in Example 1 except that a magnetic material of manganese-zinc ferrite having an electric resistance of 1.2 × 10 ¹⁰ Ωcm was used. Table 1 shows the results.

Comparative Example 1 3 kg of manganese-zinc ferrite magnetic particles having an average particle diameter of 70 μm and a saturation magnetization of 60 Am ² / kg were put into a coating apparatus (“Universal Mixing Stirrer” manufactured by Dalton).
On the other hand, 0.5 part of a thermosetting acrylic-modified silicone resin was dissolved in toluene with respect to 100 parts of magnetic particles, and this coating resin solution was added to the coating apparatus, and mixed and stirred with the magnetic particles. . At this time, set the temperature to 150 ° C,
The toluene was evaporated to cure the coating resin. The hardness was H when the coating resin solution was dried and cured at 150 ° C. and the hardness was measured by the measurement method. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Comparative Example 2 A coated carrier was prepared in the same manner as in Comparative Example 1 except that the curing temperature was changed from 150 ° C. to 180 ° C. The coating resin solution used here was dried and cured at 180 ° C., and the hardness was measured by the above-mentioned measuring method. The hardness was 2H. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Comparative Example 3 3 kg of manganese-zinc ferrite magnetic particles having an average particle diameter of 70 μm and a saturation magnetization of 60 Am ² / kg were charged into a coating apparatus (“SPIR-A-FLOW“ MINI ”manufactured by Freund Sangyo). Then, the apparatus was activated to be in a fluid state. On the other hand, 2 parts of a thermoplastic copolymer resin of methyl methacrylate and its derivative (weight average molecular weight of 30,000 to 40,000) are dissolved in toluene with respect to 100 parts of the magnetic particles, and the coating resin solution is coated with the coating solution. Supply to the device,
The surfaces of the magnetic particles were coated with the coating resin by spraying. It was dried in a fluidized state continuously at 40 ° C. for 1 hour. The resin solution for coating was dried, and the hardness was measured by the above-mentioned measuring method. The hardness was 2B. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Comparative Example 4 In the image forming apparatus, the cleaning performance was observed in the same manner as in Example 1 except that the cleaning was performed only with the cleaning brush. Table 1 shows the results.

Comparative Example 5 A resin for coating was prepared by dissolving 0.4 part of a thermoplastic copolymer resin of methyl methacrylate and its derivative (weight-average molecular weight: 10,000 to 20,000) in 100 parts of magnetic particles in toluene. A coated carrier was prepared in the same manner as in Example 1 except that a solution was prepared. The resin solution for coating was dried, and the hardness was measured by the above measuring method.
Met. The standard toner was mixed with the coated carrier, and the carrier life, image, physical properties, and cleaning performance were measured using the image forming apparatus. The results are shown in Table 1.

Comparative Example 6 A thermoplastic copolymer resin of 6 parts by weight of methyl methacrylate and its derivative (weight molecular weight: 1
(000-20,000) was dissolved in toluene, and a coated carrier was prepared in the same manner as in Example 1. Many aggregates of several cm in size were found in the coated carrier.

[0095]

[Table 1]

In the carriers for developing electrostatic latent images of Examples 1 to 14, the life of the carrier is 90 to 120 hours, which is equivalent to 350,000 to 470,000 when converted into the number of copies. I have. Further, the spent amounts after the end of printing were all negative values, confirming that the coating resin on the carrier surface was peeled off during printing. Due to the peeling of the coating resin, the difference in change in the charge amount between the initial stage and after printing is suppressed to a small value. Further, in the image forming apparatuses of Examples 1 to 14, since the coated resin pieces peeled off from the carrier surface are cleaned and removed by the cleaning blade, image stains are not seen when the number of copies is less than 200,000, and good cleaning performance is obtained. It has been shown.

On the other hand, in the carriers of Comparative Examples 1 to 3, 5 and 6, 75 hours (28.3 in terms of the number of copies).
A pull-down phenomenon occurred below. In Comparative Examples 1 and 2 using a thermosetting resin as the coating resin, the spent amount was 0.030 and 0.050 wt%, and the toner composition adhered to the carrier surface. In Comparative Examples 3 and 5, in which the thermoplastic resin was used, the spent amount was negative, and although the peeling of the coating resin was observed, the peeling speed was too high because the coating resin was soft, so that 74.1 hours, 7
At 3.0 hours, a forward pull occurred. In Comparative Example 6, the carrier could not be used because it was aggregated. On the other hand, in Comparative Example 4 in which the photosensitive member was cleaned only with the cleaning brush, the carrier life was 100 hours, and the spent amount after the end of printing was a negative value. Although the change in charge amount after printing is kept small, only the cleaning brush is used as a cleaning means for the photoreceptor, so that the coated resin pieces peeled off from the carrier surface are sufficiently cleaned and removed from the photoreceptor surface. Image stains occurred when the number of copies was less than 200,000.

[0098]

According to the carrier for developing an electrostatic latent image according to the present invention, even if toner spent is adhered, the resin surface of the carrier is peeled off one by one, and a new resin surface always appears. It can have a stable charge-imparting ability.

In the image forming apparatus according to the present invention having the above-described structure, since the carrier is used, the toner can be stably charged for a long period of time. In addition, even if the coated resin piece peeled off from the carrier surface moves and adheres to the image carrier, the cleaning blade is used as a cleaning means for the image carrier surface. Therefore, such a coated resin piece must be effectively cleaned from the image carrier surface. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus of the present invention.

FIG. 2 is a diagram schematically illustrating a suction-separation-type electrification measuring device.

FIG. 3 is a schematic sectional view of a measuring section of the main body.

[Explanation of symbols]

 1: Photoreceptor 2: Charging device 3: Exposure device 4: Developing device 5: Transfer device 6: Cleaning device 7: Main body measuring section 8: Main body control section 9: Charge meter 10: Balance 11: Suction pump 41: Developing roller 42: developer 61: cleaning brush 62: cleaning blade 71: Faraday gauge 72: wire mesh 73: insulating material (silicone rubber sheet) 74: SUS shield case 75: dust shield wire mesh (400 mesh) 76: ventilation hole (diameter) 10mm)

Claims (5)

[Claims] 1. A carrier for developing an electrostatic latent image in which the surface of magnetic particles is coated with a coating resin, wherein the coating resin is a thermoplastic resin, and the hardness of the coating resin is a pencil scratch value. A carrier for developing an electrostatic latent image, wherein the carrier is FB and the coating amount is 0.5 to 5 parts by weight based on 100 parts by weight of the magnetic particles. 2. The absolute value of the saturation charge between the magnetic particles and the toner is X (μC / g), and the absolute value of the saturation charge between the electrostatic latent image developing carrier and the toner is Y (μC / g). 2. The electrostatic latent image developing carrier according to claim 1, wherein the following formula (1) is satisfied. (Y + 2) ≦ X ≦ (Y + 10) (1) 3. The coating resin according to claim 2, wherein the particle size is 0.005 to 0.005.
1 micron chargeable and / or conductive particles are added to resin 10
The carrier for developing an electrostatic latent image according to claim 1, wherein the carrier is contained in an amount of 0.1 to 10 parts by weight based on 0 part by weight. 4. A step of developing an electrostatic latent image formed on the image carrier with a two-component developer comprising a carrier and a toner, a step of transferring a toner image on the image carrier to a recording material, 4. An image forming apparatus comprising a step of cleaning an image bearing surface of a subsequent image bearing member, wherein the carrier for developing an electrostatic latent image according to any one of claims 1 to 3 is used as a carrier. An image forming apparatus using a cleaning blade as the image forming apparatus. 5. The image forming apparatus according to claim 4, wherein the image bearing member is a photosensitive member provided with a photosensitive layer made of amorphous silicon.