JPH09319156A - Electrostatic latent image developing carrier, electrostatic latent image developer and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration and changes in image quality by forming a specified resin coating layer comprising an isocyanate compd., water, an amine compd. and a polyol compd. on a core material. SOLUTION: This carrier has a resin layer obtd. by polymn. of at least one kind of isocyanate compd. and at least one kind of material selected from water, amine compd. and polyol compd. on a core material. Since the isocyanate compd. is required to crosslink the resin and to increase the resin strength, a polyfunctional isocyanate compd. having two or more functional groups is used. The amt. of the resin coating layer in a coated carrier is preferably 0.01 to 10wt.% of the whole carrier weight, and preferably 0.2 to 5wt.%, or, the resin coating layer is preferably formed to cover >=95% surface area of the core material. Moreover, the carrier average particle size is preferably 10 to 100μm, more preferably 20 to 60μm considering the image quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a carrier for an electrostatic latent image developer, a developer and an image forming method which provide excellent image quality by having a high mechanical strength, a stable charge amount and a uniform resin coating layer. Regarding

[0002]

2. Description of the Related Art In electrophotography, a photoconductive photoconductor is charged in a dark place, an electrostatic image is formed by imagewise exposure, and the electrostatic image is developed to form a visible image. . As a method for developing a latent latent image in this way, a one-component developing method and a two-component developing method are known. The one-component developing method includes a powder cloud method, a non-magnetic one-component developing method, and a magnetic one-component developing method. Similarly, the two-component developing method includes a non-magnetic or magnetic two-component method.

Among the above-mentioned developing methods, the two-component developing method includes a coated carrier, a magnetic powder dispersion type carrier and the like.

The coated carrier is generally made of a ferromagnetic material such as iron, nickel, ferrite or the like, or a carrier core material surface obtained by dispersing these in a resin and coated with the resin. The magnetic powder-dispersed carrier is one in which a ferromagnetic material is dispersed in resin.

The carrier used in the two-component developing system functions to give a desired charge to the toner and to convey the toner to the developing area.

As a characteristic required for the carrier, it is necessary to prevent the carrier from being contaminated by the toner in order to give a desired charge to the toner. Therefore, for example, a carrier in which the surface of a carrier core material is coated with a vinylidene fluoride / tetrafluoroethylene copolymer or a polymer blend of these copolymers and a second polymer has been proposed (JP-A-58-208754). Japanese Patent Publication No. 60-1760
No. 48).

A carrier using an acrylate having a fluorine atom in a side chain as a coating resin has also been proposed (Japanese Patent Publication No. 60-16617 and JP-A No. 61-120).
169).

However, in the case of a carrier coated with a vinylidene fluoride / tetrafluoroethylene copolymer, there is a drawback that the resin is soft and durability cannot be obtained. In addition, vinylidene fluoride / tetrafluoroethylene copolymer and second
Although the adhesion of the core material is slightly improved by this polymer, the fluorine-based polymer and the second polymer are phase-separated to cause a difference in the abrasion rate in the developing machine, and the surface composition changes, resulting in charging. There was a drawback that the quantity became unstable.

In order to overcome such drawbacks, a method has been proposed in which a fluorine component is prevented from phase separation by utilizing a chemical reaction. Japanese Patent Application Laid-Open No. 25855/1990 proposes a coating method in which an OH group for reacting with an isocyanate compound is introduced into a fluorine resin to reduce phase separation of the fluorine component. Further, a technique has been proposed in which a COOH group is introduced into the fluororesin to improve the adhesiveness with the carrier core material.

However, the hydrophobic portion having a fluorine component and the hydrophilic portion having another OH group and COOH group are respectively aggregated to cause phase separation, which is not sufficient for improving the polymer blend type coated carrier. Further, since the toner contains a fluorine component, the toner has a positive charging property, and it is difficult to apply it to a negative charging toner.

Further, in the conventional resin-coated carrier, the resin coating layer does not exist with a uniform thickness with respect to the core material, the core material is exposed, and the resin coating layer thickness unevenness is large. Since these are non-uniform resin-coated carriers, there is a drawback that the image is deteriorated in the developer and the image forming method using such a coated carrier.

At present, the appearance of digital full-color copying machines / printers has dramatically improved the image quality. However, the image quality impact of the developer deterioration becomes larger than that of the conventional one, and a technique for suppressing the image quality deterioration is strongly desired.

[0013]

DISCLOSURE OF THE INVENTION The present inventors have solved the above problems of the prior art, and the present invention provides a carrier for an electrostatic latent image developer, a developer and an image forming method having the following characteristics. It is the one we are trying to provide.

1) A carrier for an electrostatic latent image developer having a sufficient mechanical strength, a developer and an image forming method using the developer provide an image quality deterioration suppressing technique.

2) Deterioration of image quality or image quality by providing a carrier for an electrostatic latent image developer, a developer and an image forming method using the developer, the charge amount of which is stable regardless of time and environment. A technique for suppressing fluctuation is provided.

3) A carrier for an electrostatic latent image developer having a uniform resin coating film, a developer and an image forming method using the developer are provided to prevent the deterioration of an image.

[0017]

Means for Solving the Problems As a result of intensive investigations by the present inventors, a composition sufficient for a carrier for an electrostatic latent image developer is obtained by using a chemical reaction of an isocyanate compound as one component at a low molecular level. It has been found that uniformity and mechanical strength (with respect to stress received in the developing machine) can be obtained, and further that a uniform resin coating film is formed. It was also found that the mechanical strength (durability) is improved by controlling the degree of crosslinking of the resin that constitutes the carrier for the electrostatic latent image developer. Further, the fluorine component added to the resin that constitutes the carrier for the electrostatic latent image developer has a function of preventing toner fusion on the surface of the carrier for the electrostatic latent image developer, but it has a surface energy different from that of other resins. Are extremely different from each other, so phase separation easily occurs. As a result, compositional non-uniformity occurs on the surface of the electrostatic latent image developer carrier, the fluororesin having weak mechanical strength is quickly worn, and as a result, the electrostatic latent image developer carrier composition changes, and The charge changes, and the image quality deteriorates or changes. The present inventors have found that by using a chemical reaction at a low molecular level, the resin constituting the carrier for the electrostatic latent image developer can have sufficient composition uniformity and the above-mentioned drawbacks can be improved. Alternatively, by removing the fluorine-based and silicone-based components from the carrier, the nonuniformity of the resin composition due to the phase separation of the carrier for the electrostatic latent image developer is fundamentally eliminated, and the release component fluorine and silicone components are removed. The present invention has been completed by finding that it becomes difficult for the toner to be fused to the surface of the carrier for the electrostatic latent image developer by adding it to the toner external additive.

More specifically, the above object of the present invention is: (1) On a core material, at least one isocyanate compound and at least one substance selected from the group consisting of water, an amine compound and a polyol compound. It is achieved by using a carrier for an electrostatic latent image developer, which has a resin coating layer obtained by polymerization from.

(2) The carrier for electrostatic latent image developer according to item (1) above, wherein the resin coating layer comprises a resin obtained by polymerizing at least one isocyanate compound and water. Achieved by using.

(3) The carrier for an electrostatic latent image developer according to item (1), wherein the content of the resin coating layer is 0.01 to 10% by weight based on the total weight of the carrier. Was achieved by using

(4) Achieved by using the carrier for electrostatic latent image developer described in (1) above, wherein the resin coating layer is present in an amount of 95% or more with respect to the surface area of the core material. It was

(5) The average particle diameter of the carrier is 10 to
It was achieved by using the carrier for electrostatic latent image developer described in the item (1), which is 100 μm.

(6) It is achieved by using an electrostatic latent image developer characterized by comprising a toner and the carrier described in the above item (1).

(7) The average particle size of the toner is 3 to 9 μm.
It was achieved by using the electrostatic latent image developer described in the above item (6), which is characterized in that m.

(8) It is achieved by using the electrostatic latent image developer described in the above item (6), wherein the toner contains a linear polyester as a binder resin.

(9) The toner according to item (6) above, wherein the toner contains an additive surface-treated with at least one compound selected from the group consisting of fluorine compounds and silicone compounds. Achieved by using a latent image developer.

(10) In an image forming method of developing an electrostatic latent image on an electrostatic latent image bearing member by using a developer layer on the developer bearing member, the developer comprises toner and carrier.
This is achieved by using an image forming method characterized in that the carrier comprises the carrier described in the item (1).

Hereinafter, the present invention will be described in detail. The carrier for an electrostatic latent image developer in the present invention (hereinafter, simply referred to as a carrier) is a so-called coated carrier in which a core material is covered with a resin, but a so-called magnetic substance-dispersed carrier in which magnetic powder is dispersed in the resin is used. You can also

The resin used in the present invention is a resin obtained by polymerizing at least one isocyanate compound and at least one substance selected from the group consisting of water, amine compounds and polyol compounds.

Since the isocyanate compound used in the present invention is required to crosslink the resin to increase the resin strength, a polyfunctional isocyanate compound having a functionality of 2 or more is used. For example, the following can be mentioned. As the bifunctional isocyanate compound, for example, a commercial product name:
Hexamethylene diisocyanate such as "Sumijour H" (Sumitomo Bayer Urethane Co.), commercial product name: Metaphenylene diisocyanate such as "Nafconate" (National Aniline Co.), commercial product name: "Suminate 80" (Sumitomo Chemical Co., Ltd.) Toluylene diisocyanate (Toluylene-2,4-diisocyanate and Torelene-2)
Mixture of 6-diisocyanate), commercial product name: 2, such as "Sumijour T" (Sumitomo Bayer Urethane Co.)
4-Tolylene diisocyanate, commercially available product name: 3,3′-dimethyl-diphenyl-such as “HIREN H” (manufactured by DuPont) and “Suminate BT” (manufactured by Sumitomo Chemical Co., Ltd.)
4,4′-diisocyanate, commercial product name: “Millionate MT” (manufactured by Nippon Polyurethane Industry Co., Ltd.) and “Isona
te 125M "(manufactured by Kasei Upjohn Co.) and" Sumijour 44S "(manufactured by Sumitomo Bayer Urethane Co., Ltd.), commercial product name: 3,3'- such as" Hiren DM "(manufactured by DuPont) Naphthalene diisocyanate such as dimethyl-diphenylmethane-4,4′-diisocyanate, commercial product name: “Sumijour 15” (manufactured by Sumitomo Bayer Urethane Co.), commercial product name: such as “Desmodur W” (manufactured by Sumitomo Bayer Urethane Co.) Examples thereof include dicyclohexylmethane diisocyanate, and a diphenyl ether diisocyanate such as a commercially available product name: "Suminate E" (manufactured by Sumitomo Chemical Co., Ltd.).

Examples of the modified bifunctional isocyanate compound other than the above are, for example, "Sumijour 44".
p-90 "," Sumijour 3062 "," Sumijour PF "," Sumijour CD "," Sumijour 06 "
32 "," Sumijour PC "(all manufactured by Sumitomo Bayer Urethane Co., Ltd.)," Coronate 2014 "," Coronate A "
P "," Coronate 2501 "," Millionate MS-
50 "," Coronate 3041 "(all manufactured by Nippon Polyurethane Industry Co., Ltd.)," Duranate 24A-90CX ",
"Duranate EXPD-101" (all manufactured by Asahi Kasei Corporation), "Takenate M-402", "Takenate F-5"
13 "," Takenate D-102 "," Takenate L- "
1150 "(manufactured by Takeda Pharmaceutical Co., Ltd.) and the like, and any one having two isocyanate groups can be generally used.

As the trifunctional isocyanate compound, for example, a hexamethylene diisocyanate adduct such as a commercial product name: "Sumijour N" (manufactured by Sumitomo Bayer Urethane Co.), a commercial product name: Sumijour L "(manufactured by Sumitomo Bayer Urethane Co.) Or a reaction product of trimethylolpropane with toluylene isocyanate such as "Coronate L" (manufactured by Nippon Polyurethane Industry Co., Ltd.), a commercial product name: triphenylmethane such as "Sumijour R" (manufactured by Sumitomo Bayer Urethane Co.) Triisocyanate, commercial product name: reaction product of hexamethylene diisocyanate such as "Coronate HL" (manufactured by Nippon Polyurethane Industry Co., Ltd.) and trimethylolpropane, commercial product name: "Desmodur E
Hexamethylene diisocyanate adduct such as "H" (Sumitomo Bayer Urethane Co., Ltd.), commercial product name: "Isona
te143L "(manufactured by Kasei Upjohn) and a diphenylmethine diisocyanate cycloadduct, and a commercially available product name: 2-isocyanateethyl-2,6-diisocyanate hexanoate such as" T-100 "(manufactured by Toray). be able to. Modified 3 other than the above
As the functional isocyanate compound, "Takenate D-1" is used.
10N "(manufactured by Takeda Pharmaceutical Co., Ltd.) and the like.

As the polyfunctional isocyanate compound having more than 3 functionalities, for example, a compound represented by the following formula,

[0034]

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Examples thereof include an adduct of diphenylmethane diisocyanate and a polyhydric polyol, and an adduct of toluylene diisocyanate and a polyhydric polyol.

Although these do not exist as pure products, as commercially available products containing bifunctional and polyfunctional (trifunctional or higher), for example, "Sumijour 44V-10",
"Sumijour 44V-20", "SBU-Isocy
anate 0389 "(all manufactured by Sumitomo Bayer Urethane Co., Ltd.)," Millionate MR "(manufactured by Nippon Polyurethane Industry Co., Ltd.)," PAPI135 "," PAP20 "(all manufactured by Kasei Upjohn Co., Ltd.) and the like.

Among them, as the isocyanate compound,
Trifunctional or higher polyfunctional isocyanates are preferred from the viewpoint of effectiveness.

The amine compound that reacts with the isocyanate compound is preferably a bifunctional or higher functional compound, and the following compounds can be exemplified.

As the bifunctional amine compound, ethylenediamine, hexamethylenediamine, phenylenediamine, xylylenediamine, diaminocyclohexane, piperazine, 4,4'-diaminodiphenylmethane, 4,
4'-diaminodiphenyl ether, 4,4'-diaminostilbene-2,2'-sulfonic acid, its sodium salt, etc. are mentioned. Examples of trifunctional or higher functional amine compounds include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, triaminobenzene and melamine monomers. Of these, trifunctional or higher functional amine compounds are preferable, and diethylenetriamine and melamine monomers are particularly preferable from the viewpoint of charge retention.

Further, an amine compound containing a fluorine component or a silicone component can be preferably used when it is desired that the surface of the carrier has a low surface energy.

The following compounds can be exemplified as the amine compound having a fluorine component.

[0042]

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The following compounds can be exemplified as the amine compound having a silicone component.

[0044]

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The amine compound containing a fluorine component or a silicone component can be used even if it is monofunctional.

Examples of the polyol compound which reacts with the isocyanate compound include diol compounds such as ethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol and neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-. Examples include triol compounds such as hexanetriol, pentaerythritol, and the like, and diol compounds are particularly preferably used.

Further, a polyol compound containing fluorine or a silicone component can be preferably used.

Examples of the polyol compound having a fluorine component include the following.

[0049]

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Examples of the polyol compound having a silicone component include the following.

[0051]

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A polyol compound containing a fluorine component or a silicone component can be used even if it is monofunctional.

The resin of the resin coating layer formed on the core material in the present invention is a urea bond and / or a urethane bond obtained by polymerizing an isocyanate compound with water, an amine compound and / or a polyol compound which reacts with the isocyanate compound. It is a resin containing. Isocyanate compounds and combinations of these substances that react with them are not particularly limited, but for example, isocyanate compounds and water, isocyanate compounds and amine compounds, isocyanate compounds and polyol compounds,
Examples thereof include an isocyanate compound and two or more kinds of these substances. In addition, these isocyanate compounds,
The amine compound and the polyol compound are each alone,
Alternatively, it is used as a mixture of two or more kinds. Of these, a combination of an isocyanate compound and water is preferable from the viewpoint of controlling the chargeability.

The proportions of the isocyanate compound and various substances that react with the isocyanate compound can be arbitrarily selected according to the purpose because various resins can be obtained depending on their relative amounts, but no unreacted compound or substance remains after the reaction. Since it is preferable from the viewpoint of maintaining storage stability, it is generally used in an amount such that the isocyanate functional group and the functional groups of various substances that react with it react stoichiometrically.

One feature of the present invention is that it provides a new technical idea of controlling the degree of crosslinking of the resin constituting the carrier, and is selected from at least one or more isocyanates and water, amine compounds, and polyol compounds. By mixing and polymerizing at least one kind of substance, it is possible to provide a carrier having good composition uniformity and excellent mechanical strength and having a uniform resin coating film formed thereon.

In the present invention, the resin derived from an isocyanate compound can be used by dispersing additives such as various oxides, polymer beads and carbon black.

Known methods can be used as the method for producing the carrier in the present invention. An example is given below.

As a method for producing a coated carrier, an isocyanate compound is diluted with a solvent as needed, and this is mixed with a carrier core material and stirred to remove the solvent. Then water,
There is a method in which a predetermined amount of an amine compound and / or a polyol compound is added and allowed to react while being mixed or left standing. At this time, heating can be performed if necessary. When a large amount of low surface energy substance is desired to be present on the carrier surface, it can be obtained by, for example, adding a fluorine-containing amine compound or a fluorine-containing polyol compound at the end. Alternatively, when it is desired to obtain a coating layer having a uniform composition in the depth direction, the isocyanate compound is diluted with a solvent as required, and water, an amine compound and / or a polyol compound, which are substances that react with the isocyanate compound, are added, and There is a method of carrying out the reaction by removing the solvent while stirring and mixing with the carrier core material, or by leaving it to stand and removing the solvent.

Further, the carrier core material and the isocyanate compound are mixed and stirred in advance, and the mixture is put into water or a solution containing the reaction partner amine compound and / or polyol compound, and the reaction is carried out in a liquid to give a coated carrier. There is a method of manufacturing.

One feature of the present invention is that a carrier having a uniform resin coating film on the core material can be provided, and as a result, an image resulting from a carrier having a conventional non-uniform resin coating layer can be formed. Deterioration can be prevented. A carrier having this uniform resin coating film can be easily prepared, for example, by coating the surface of a core material with an isocyanate compound and the above-mentioned substance that reacts therewith, and then allowing it to stand (heat as necessary) to cause a polymerization reaction. Can be obtained.

The magnetic powder-dispersed carrier can be obtained by stirring and mixing a mixture of magnetic powder and an isocyanate compound in water or in a solution containing an amine compound and / or a polyol compound as a reaction partner and reacting. it can.

The content of the resin coating layer of the coated carrier in the present invention is 0.01 to 10 relative to the total weight of the carrier.
%, Preferably 0.2 to 5% by weight from the viewpoint of effect. If the amount is less than 0.01% by weight, the carrier coating layer becomes non-uniform, which makes it difficult to control the carrier resistance value. 1
If it exceeds 0% by weight, the magnetic force becomes weak, and it becomes difficult to exhibit the function as a carrier. As the carrier core material, known materials such as ferrite, magnetite, iron, cobalt, nickel and other ferromagnetic metals can be used.

For the magnetic powder-dispersed carrier, a known metal having magnetism can be used, and the amount of the magnetic powder is preferably 70 to 95% by weight with respect to the total weight of the carrier as the magnetic force of the carrier.

The resin coating layer of the carrier of the present invention is preferably present in an amount of 95% or more based on the surface area of the core material. The presence of a coating layer of 95% or more of the surface area of the core material means that the exposed portion of the surface of the core material is less than 5%, and that the resin layer is uniformly and uniformly coated on the core material. Meaning and is a measure of the uniformity of the coating layer. This uniformity is evaluated by the X-ray photoelectron spectroscopy (ESCA) method (JEOL Ltd. JP
S-80) and the amount of exposure of the core material (Fe). If this value is less than 95%, that is, non-uniformity, the image is deteriorated.

Further, in this uniform resin-coated carrier, the core material is coated with the resin produced by the chemical reaction of the substance containing the isocyanate compound at the low molecular level as described above. It is possible to form a uniform thin film, and for example, it is possible to obtain a carrier having an ultrathin film uniform coating having a thickness of 0.1 μm or less. In this case, even if it is a thin film, the carrier resistance value is lowered, but since the uniform film suppresses the charge injection due to the developing bias to the carrier, the carrier does not migrate to the photoconductor.

The average particle size of the carrier in the present invention is 10
˜100 μm is preferable from the viewpoint of image quality, and further 20 to 6
0 μm is more preferred. If it is less than 10 μm, it becomes difficult to manufacture the carrier, and agglomeration easily occurs during the manufacturing of the carrier. If it exceeds 100 μm, the image quality is deteriorated. Further, the electric resistance value of the carrier itself is obtained by dispersing conductive powder such as carbon black in the resin forming the carrier.
It can be adjusted arbitrarily.

The present invention also provides an electrostatic latent image developer comprising toner and the carrier. Known toners can be used in the present invention.

The toner is a binder resin in which a colorant or the like is dispersed. The binder resin used in the toner is
Styrenes such as styrene, parachlorostyrene, α-methylstyrene: methyl (meth) acrylate, (meth)
Ethyl acrylate, n-propyl (meth) acrylate,
Lauryl (meth) acrylate, (meth) acrylic acid 2-
Α-Methylene aliphatic monocarboxylic acid esters such as etherhexyl: vinyl nitriles such as acrylonitrile and methacrylonitrile: 2-vinylpyridine, 4-
Vinyl pyridines such as vinylyl pyridine: Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether: Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone: unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene And its halides, homopolymers of monomers such as halogenated unsaturated hydrocarbons such as chloroprene, and copolymers obtained by combining two or more of these monomers, and mixtures thereof. Furthermore,
Rosin-modified phenol formalin resin, epoxy resin,
Examples thereof include polyester resins such as linear polyester, polyurethane resins, polyamide resins, cellulose resins, non-vinyl condensation resins such as polyether resins, and mixtures of these with the vinyl resins. Of these, linear polyester is preferable.

Examples of the colorant used in the toner include carbon black, nigrosine dye, aniline blue, calcoil blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, phthalocyanine blue, and mixtures thereof.

As the toner component other than the colorant, there are a charge control agent, an anti-offset agent and the like, and a magnetic fine powder may be contained if necessary. Preferably, components such as a charge control agent such as a salicylic acid metal salt, a metal-containing azo compound, nigrosine and a quaternary ammonium salt, and an offset preventive agent such as low molecular weight polypropylene, low molecular weight polyethylene and wax can be added.

A fluidizing agent such as silica, titania and alumina, a cleaning aid such as polystyrene fine particles, polymethyl methacrylate fine particles and polyvinylidene fluoride fine particles, or an external additive such as a transfer aid can also be used.

Since the carrier in the present invention has a very high mechanical strength, it hardly wears.

Since the toner used in the present invention contains additives such as silica and titania surface-treated with a fluorine compound and / or a silicone compound, the fusion of the toner to the carrier is extremely reduced. preferable.

The average particle diameter of the toner used in the present invention is preferably 3 to 9 μm. In the present invention, the developer comprising the toner and the carrier of the present invention is used in the usual image forming method of developing the electrostatic latent image on the electrostatic latent image carrier by using the developer layer on the developer carrier. An image forming method is also provided.

[0075]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 Cu-having an average particle diameter of 50 μm
20 g of trifunctional isocyanate (trade name Takenate D110N, manufactured by Takeda Pharmaceutical Co., Ltd.) and 150 g of ethyl acetate were added to 3 kg of Zn ferrite, and the mixture was stirred and mixed at 60 ° C. with a pressure kneader. Next, ₂₀₀ g of H ₂ O was added and mixed with stirring at 120 ° C., and the solvent was removed under reduced pressure. The obtained carrier was sieved with a 75 μm mesh to obtain the carrier of the present invention. As a result of evaluation by the ESCA method, this carrier was confirmed to be a uniform resin-coated carrier in which the core material surface was covered with a resin layer at 99.5%.

Toner for color copying machine Acolor 635 manufactured by Fuji Xerox Co., Ltd. is used as a carrier of the present invention and TC.
= 8%, mixed, placed in the Acolor 635 copier and tested for 200,000 copies.

In this test, the image quality did not change even in the summer environment and the winter environment, and no deterioration in image quality was observed from the initial stage up to 200,000 sheets. The amount of coating resin with respect to the carrier was measured by a thermal analyzer, and the value obtained by dividing the amount of coating resin by the total weight of the carrier was 0.5% by weight for a fresh carrier, and 0.48% by weight after 200,000 sheets. There was little change. [Example 2] 40 g of a trifunctional isocyanate (trade name Takenate D110N, manufactured by Takeda Pharmaceutical Co., Ltd.) and bifunctional isocyanate (trade name Sumidule T, with respect to 3 kg of Cu-Zn ferrite having an average particle diameter of 50 µm) 20 g of Sumitomo Bayer Urethane Co., Ltd. and 4 g of carbon black (trade name VXC-72, manufactured by Cabot Co.) were added, 150 g of ethyl acetate was further added, and the mixture was stirred and mixed at 60 ° C. with a pressure kneader. Next, a reactive silicone oil having amino groups on both ends of the silicone component (trade name X-
22-161A, manufactured by Shin-Etsu Silicone Co., Ltd.) and 5 g of diethylenetriamine were added, and the mixture was stirred and mixed at 120 ° C. for 30 minutes to remove the solvent. The obtained carrier was sieved with a 75 μm mesh to obtain the carrier of the present invention. As a result of evaluation by the ESCA method, this carrier was confirmed to be a uniform resin-coated carrier in which the surface of the core material was covered with a resin layer at 99.8%.

A toner for color copying machine Acolor 635 manufactured by Fuji Xerox Co., Ltd. is used as a carrier of the present invention and TC.
Mix at 8%, put in the Acolor 635 copier,
A copy test was performed on 200,000 sheets.

In this test, the odors in the summer and winter environments
However, there is no change in image quality, and there is no deterioration in image quality from the beginning to 200,000 sheets.
I couldn't see it. Example 3 Hydrophilic silica (trade name Aerosil 1
30, manufactured by Nippon Aerosil Co., Ltd.) 100 g of toluene 200
silane coupling agent: C₈F
₁₇(CH _Two)_TwoSi (OCH_Three)_Three Add 30g 60
The mixture was stirred and mixed at ℃, and the solvent was removed under reduced pressure. 1 more
After leaving it in an oven at 50 ° C for 2 hours, crush it with a mill and surface it.
A treated external additive was obtained.

To 1 kg of a toner base material for a color copying machine Acolor 635 manufactured by Fuji Xerox Co., Ltd., 10 g of the surface-treated external additive was blended with a Henschel mixer and further sieved to obtain a toner. Example 1 of this toner
Of the present invention are mixed at TC = 8%, and the Aco
It was placed in a Lor635 copier and a copy test of 400,000 sheets was performed.

In this test, the image quality did not change even in the summer environment and the winter environment, and the initial high image quality was almost achieved even after 400,000 sheets. The value obtained by dividing the amount of the coating resin with respect to the carrier by the total weight of the carrier was 0.5% by weight with a fresh carrier, and 0.45% by weight after 400,000 sheets were printed. Almost no peeling from the core material was observed.

[Comparative Example 1] Cu-having an average particle diameter of 50 μm
20 g of trifunctional isocyanate (trade name Takenate D110N, manufactured by Takeda Pharmaceutical Co., Ltd.) and 150 g of ethyl acetate were added to 3 kg of Zn ferrite, and the mixture was stirred and mixed at 60 ° C. with a pressure kneader. Next, 5 g of castor oil was added, and the mixture was stirred and mixed at 120 ° C., and the solvent was removed under reduced pressure.
The obtained carrier was sieved with a 75 μm mesh to obtain a carrier of Comparative Example.

Toner for color copying machine Acolor 635 manufactured by Fuji Xerox Co., Ltd. was used as a carrier for comparison and TC.
= 8%, mixed, placed in the Acolor 635 copier and tested for 200,000 copies.

In this test, the image quality was good in the summer environment and the winter environment, but the image quality was greatly deteriorated from the initial stage to 200,000 sheets. The amount of coating resin with respect to the carrier was measured by a thermal analysis device, and the value obtained by dividing the amount of coating resin by the total weight of the carrier was 0.52% by weight of a fresh carrier,
After 200,000 sheets, it was 0.31% by weight, and the abrasion of the coating layer was remarkable.

[0086]

Since the carrier for electrostatic latent image developer, the developer and the image forming method of the present invention have the above-mentioned constitutions, a carrier having a high mechanical strength, a stable charge amount and a uniform resin coating layer can be used. It is possible to provide excellent image quality.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Masahiro Takagi 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Akihiro Iizuka 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Masanori Ichimura 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (10)

[Claims] 1. A resin coating layer obtained by polymerizing at least one isocyanate compound and at least one substance selected from the group consisting of water, an amine compound and a polyol compound on the core material. Characteristic carrier for electrostatic latent image developer. 2. The carrier for an electrostatic latent image developer according to claim 1, wherein the resin coating layer is made of a resin obtained by polymerizing at least one isocyanate compound and water. 3. The carrier for an electrostatic latent image developer according to claim 1, wherein the content of the resin coating layer is 0.01 to 10% by weight based on the total weight of the carrier. 4. The resin coating layer, relative to the surface area of the core material,
The carrier for an electrostatic latent image developer according to claim 1, wherein the carrier is present in an amount of 95% or more. 5. The carrier has an average particle diameter of 10 to 10.
The carrier for an electrostatic latent image developer according to claim 1, wherein the carrier is 0 μm. 6. An electrostatic latent image developer comprising a toner and the carrier according to claim 1. 7. The electrostatic latent image developer according to claim 6, wherein the toner has an average particle diameter of 3 to 9 μm. 8. The electrostatic latent image developer according to claim 6, wherein the toner contains a linear polyester as a binder resin. 9. The electrostatic latent image according to claim 6, wherein the toner contains an additive surface-treated with at least one compound selected from the group consisting of fluorine compounds and silicone compounds. Developer. 10. Using a developer layer on a developer carrier,
An image forming method for developing an electrostatic latent image on an electrostatic latent image carrier, wherein the developer comprises toner and a carrier, and the carrier comprises the carrier according to claim 1. Method.