JPH1010791A - Electrostatic latent image developing carrier, developer and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesion of a carrier to a core material, the impact resistance, the wear resistance and the toner contamination resistance by providing a resin coating layer containing a specific polycarbonate compound on the core material. SOLUTION: An electrostatic latent image developing carrier has the resin coating layer containing the polycarbonate compound expressed by a formula on the core material. In the formula, R1 is a 2-valent alkylene group or an aryl group, R2 is a 1-5C 2-valent alkylene group an R3 is a 1-3C alkyl group. And N:Y=1:1 to 1:0.01 and N=30-5000. A well-known magnetic material is used as the core material. Concretely, a magnetic oxide particle such as an iron powder, magnetite, ferrite and a dispersed particle obtained by dispersing the powder in a thermoplastic resin or thermosetting resin are enumerated. The core material having 10-500μm, more preferably 30-150μm average particle diameter is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a carrier for developing an electrostatic latent image used for developing an electrostatic latent image on an electrostatic latent image carrier, a developer, and an image forming method.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, an electrostatic latent image is formed on a photoreceptor or an electrostatic recording material using various means, and electrostatic fine particles called toner are attached to the electrostatic latent image. Then, a method of developing an electrostatic latent image is generally used. In this development, a two-component developer consisting of carrier particles and toner particles, called a carrier, is used, and the two are mixed and frictionally charged with each other to impart an appropriate amount of positive or negative charge to the toner.

[0003] Carriers are generally classified into coated carriers having a coating layer on the surface and non-coated carriers having no coating layer on the surface. Therefore, various coated carriers have been developed and put into practical use.

There are various characteristics required for the coated carrier, but it is necessary to impart a proper chargeability (charge amount and charge distribution) to the toner and to maintain an appropriate chargeability of the toner for a long period of time. It is particularly important that the chargeability of the toner is not changed even with environmental changes such as impact resistance, abrasion resistance, and humidity and temperature, and various coated carriers have been proposed.

[0005] For example, as one of methods for improving the impact resistance and abrasion resistance of a coated carrier, a method of applying various coupling agents to the surface of a core material to improve the adhesion between the core material and the coat layer is known. JP-A-59-200259 also discloses
JP-A-64-29858 describes coating a core material with particles containing a charge controlling agent by mechanical force.

[0006] When these methods are used, the adhesion between the core material and the coat layer is improved. However, since a substance having a charge control function is used at that time, the substance is charged due to environmental fluctuation due to this substance. However, there is a problem that the toner component adheres to the carrier with the passage of time in an actual machine.

[0007] Japanese Patent Application Laid-Open No. 7-84413 discloses that
A carrier in which magnetic particles are coated with a resin containing a polydiorganosiloxane polycarbonate block copolymer represented by the following general formula (2) is described.

[0008]

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It is described that the use of the binder resin improves the impact resistance of the carrier, the stability of charging the toner, and provides excellent developability and developer life. Even if a coated carrier is prepared by further coating the core material with various coupling agents with respect to the binder resin, the adhesion between the core material and the coat layer cannot be improved, and toner contamination can be prevented. As for the properties, deterioration with the lapse of time was observed in the actual machine, which was not satisfactory. Especially,
When a full-color toner is used, the stability of the developer decreases due to a decrease in the charge amount under high temperature and high humidity and an extreme increase in the charge amount under low temperature and low humidity. There are problems such as image fogging and density unevenness.

[0010] As described above, a carrier coating material which is required to sufficiently extend the life of the developer and has excellent adhesion, impact resistance, toner contamination resistance and the like has not yet been found.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and has an excellent adhesion to a carrier core material.
An object of the present invention is to provide a long-life electrostatic latent image developing carrier, a developer, and an image forming method which have impact resistance, abrasion resistance, and are effective for toner contamination and the like. Another object of the present invention is to provide an electrostatic latent image developing carrier suitable for use with a color toner.

[0012]

The present invention has succeeded in solving the above-mentioned problems by adopting the following constitution. (1) An electrostatic latent image developing carrier, comprising a core and a resin coating layer containing a polycarbonate compound represented by the following general formula (1).

[0013]

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(2) The carrier for developing an electrostatic latent image according to the above (1), wherein the magnetic material particles are used as a core material as it is. (3) The carrier for developing an electrostatic latent image according to the above (1), wherein particles obtained by dispersing a magnetic material powder in a binder resin are used as a core material.

(4) The above-mentioned (1), wherein the reaction is carried out in the presence of a phase transfer catalyst in an organic solvent in which the raw material polycarbonate resin and the glycidyloxy group-containing silane coupling agent are dissolved.
A method for producing a carrier for developing an electrostatic latent image, comprising coating a core material with the polycarbonate compound described above.

(5) The electrostatic latent image development as described in (4) above, wherein a crosslinking reaction is promoted by adding a small amount of water or a basic catalyst such as sodium hydroxide to the water in the above reaction. Of manufacturing carrier for

(6) An electrostatic latent image developer comprising the carrier according to any one of the above (1) to (3) and a toner. (7) The above (6), wherein a color toner is used.
The electrostatic latent image developer as described in the above.

(8) Using the developer layer on the developer carrier,
An image forming method for developing an electrostatic latent image on an electrostatic latent image carrier, wherein the image is formed using the developer according to the above (6) or (7).

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The polycarbonate compound represented by the general formula (1) used in the present invention has a structure that causes a cross-linking reaction with the surface of the core material of the carrier, and a strong film is formed. Adhesive, and polycarbonate skeleton oriented on the surface has low surface energy,
It has abrasion resistance and impact resistance, so it has excellent contamination resistance to toner, and as a result, it has a low environmental dependency and can withstand continuous use for a long period of time. Made available. Further, it has become possible to provide a method capable of forming a good image without unevenness or fogging of the image even when the environment changes.

The polycarbonate compound used in the present invention is represented by the above general formula (1), and specific examples thereof include those described in Tables 1 to 7 below.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

[0027]

[Table 7]

The polycarbonate compound used in the present invention can be synthesized by the following reaction formula. ("J. A
ppl. Poly. Sci. Vol. 56, pp1-8 (1995) ”)

[0029]

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Examples of the polycarbonate resin used as a raw material of the above-mentioned polycarbonate compound include polyethylene carbonate, polybisphenol A carbonate, polybiphenyl carbonate, polybiphenyl sulfone carbonate, polyphenyl carbonate, polybenzophenone carbonate, polyperbromophenyl carbonate, and polyperfluorocarbon. Examples thereof include fluorophenyl carbonate and polybisphenol AF carbonate.

The glycidyloxy group-containing silane coupling agent used for synthesizing the above-mentioned polycarbonate compound is, for example, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 2-glycidyloxyethyl. Examples thereof include trimethoxysilane, glycidyloxymethyltrimethoxysilane, and 4- (glycidyloxy) benzyltrimethoxysilane.

Incidentally, the above-mentioned polycarbonate compound is synthesized by reacting the above-mentioned glycidyloxy group-containing silane coupling agent with a polycarbonate resin as a raw material in an organic solvent in which this resin is dissolved, using a phase transfer catalyst. Examples of the phase transfer catalyst used for synthesizing the polycarbonate resin include compounds such as crown ether derivatives, quaternary ammonium salts, and phosphonium salts, specifically, tetramethylammonium chloride,
Quaternary ammonium salts such as tetraethylammonium chloride, tetra-n-butylammonium bromide, tetraethylammonium chloride, benzyltrimethylammonium chloride, tetraethylammonium fluoride, and quaternary phosphonium salts such as n-butyltriphenylphosphonium bromide; And crown ethers such as crown 4-ether.

As the organic solvent for dissolving the polycarbonate resin as a raw material, a glycidyloxy group-containing silane coupling agent such as dichloromethane, trichloroethane, toluene, acetone, xylene, methyl ethyl ketone, methyl isobutyl ketone, and dimethyl formamide does not react. Any organic solvent can be used as long as it can dissolve the polycarbonate resin as a raw material.

A known magnetic material can be used as the core material used in the present invention. Specifically, iron powder, magnetite, magnetic oxide particles such as ferrite, and also, dispersed particles obtained by dispersing these powders in a thermoplastic resin or a thermosetting resin can be used, and these may be used alone. Can be used together. Specific examples of a thermoplastic resin or a thermosetting resin in which magnetic oxide powders such as iron powder, magnetite, and ferrite are dispersed include polyolefin resins, polyester resins, polyurethane resins, polycarbonate resins, melamine resins, and phenol resins. And the like.

The average particle size of the magnetic powder in the magnetic powder-dispersed carrier is 0.01 to 10 μm, preferably 0.05 to 10 μm.
The range is 5 μm. The core material of the present invention has an average particle size of 10 to 500 µm, and more preferably 30 to 150 µm.

The surface of the core material is coated with the above polycarbonate compound by a dipping method in which the core material is dipped in a solvent for forming the coating layer, a spray method in which a solution for forming the coating layer is sprayed on the surface of the core material, A fluidized bed method in which the core material is suspended in fluidized air and a coating layer forming solution is sprayed, a kneader coater method in which the core material and the coating layer forming solution are mixed in a kneader coater, and the solvent is removed. it can.

In order to strongly crosslink the polycarbonate compound on the surface of the core material, the drying temperature is set to 30 to
It is good to set to 250 ° C., preferably 50 to 200 ° C. In addition, upon coating, a small amount of water or distilled water, or by adding a basic catalyst such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate to these, to promote cross-linking Is desirable.

The solvent used for the coating solution for forming the coating layer is as follows:
If it can dissolve the polycarbonate compound,
It can be used regardless of its type. For example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used. The thickness of the coating layer is usually 0.1 to 10 μm, preferably 0.1 to 5 μm.
A range of 0 μm is suitable.

[0039]

The present invention will be described in detail with reference to the following examples (Examples of synthesis of compound having structure No. 1) 10.0 g of polyethylene carbonate resin [weight average molecular weight (Mw) 50,000, gel permeation chromatography (GPC)] Value) and 3-glycidoxypropyltrimethoxysilane 1.0 as a glycidyloxy group-containing coupling agent.
g (4.23 mmol) in 100 ml of dichloromethane
And 0.05 g (0.16 mmol) of tetraethylammonium bromide as a phase transfer catalyst was added. Dichloromethane was removed with slow heating. When the internal temperature reached 60 ° C., the removal operation was terminated.
The reaction was performed for 4 hours.

A part of the obtained reaction product was collected, added to petroleum ether, and the precipitated solid was analyzed by NMR. It was confirmed that this was the first target. In the formula, N: Y = 1: 1, and N =
570. The remaining reaction product was used as it was as a carrier coating material.

(Synthesis example of compound of structure No. 10) Polyperfluorophenyl carbonate resin [weight average molecular weight (Mw) 70,000, gel permeation chromatography (GPC) value] in place of polycarbonate resin of compound synthesis example 1 And the reaction was carried out in the same manner as in Compound Synthesis Example 1 except that 4- (glycidyloxy) benzyltrimethoxysilane was used as the glycidyloxy group-containing coupling agent. 10 target compounds were obtained (NMR
Confirm with). In the formula, N: Y = 1: 1
And N = 340. The reaction product was used as it was as a carrier coating material.

(Synthesis Example of Compound of Structure No. 23) Instead of the polycarbonate resin of Compound Synthesis Example 1, a polybisphenol A carbonate resin [weight average molecular weight (M
w) 60,000, gel permeation chromatography (GPC) value] and 3-glycidoxypropyltrimethoxysilane as a glycidyloxy group-containing coupling agent, and reacted in the same manner as in Compound Synthesis Example 1. Structure No. 23 target compounds were obtained (confirmed by NMR).
In the formula, N: Y = 1: 1 and N
= 240. The reaction product was used as it was as a carrier coating material.

(Synthesis Example of Compound of Structure No. 28) Instead of the polycarbonate resin of Compound Synthesis Example 1, a polybisphenol AF carbonate resin [weight average molecular weight (M
w) 80,000, gel permeation chromatography (GPC) value], and using 3-glycidoxypropyltrimethoxysilane as the glycidyloxy group-containing coupling agent, in the same manner as in Compound Synthesis Example 1. Structure No. 28 objective substances were obtained (confirmed by NMR).
In the formula, N: Y = 1: 1 and N
= 80. The reaction product was used as it was as a carrier coating material.

Example 1 Structure No. The polycarbonate resin of No. 1 was dissolved in toluene so as to have a solid content of 10%, and magnetite particles having an average particle diameter of 50 μm were used as a core material of the carrier. The polycarbonate resin solution was added so as to be 2 parts by weight, and coating and carrying were performed at 80 ° C. with a kneader coater to obtain a coated carrier having a thickness of 0.25 μm.

Example 2 Structure No. 10 weight percent solid content of polycarbonate resin in methyl ethyl ketone
So that the carrier has a mean particle size of 5
Using 0-μm Cu-Zn ferrite particles, 100 parts by weight of the ferrite particles, the polycarbonate resin solution was added so that the solid content weight is 1.2 parts by weight, further, 100 parts by weight of the polycarbonate resin Then, 1.0 part by weight of distilled water was added, and coating and carrying were performed at 100 ° C. by a kneader coater to obtain a coated carrier having a thickness of 0.25 μm.

Embodiment 3 Structure No. Polycarbonate resin No. 14 in tetrahydrofuran with a solid content of 10%
Is used, and magnetite powder (average particle diameter: 0.5 μm, 80% by weight) dispersed in polyurea is used as a core material of the carrier, and particles having an average particle diameter of 50 μm are used. The polycarbonate resin solution was added such that the minute weight was 1.2 parts by weight,
Further, 1.0 part by weight of a 0.1% by weight sodium hydroxide solution is added to 100 parts by weight of the polycarbonate resin, and coating and carrying are performed at 100 to 120 ° C. by a kneader coater to form a coating having a thickness of 0.25 μm. Got a career.

Embodiment 4 Structure No. Polycarbonate resin No. 17 in tetrahydrofuran with a solid content of 10%
So that the carrier has a mean particle size of 4
Using 0 μm magnetite particles, the above-mentioned polycarbonate resin solution was added to 100 parts by weight of the magnetite particles so that the solid content was 1.2 parts by weight, and coating and carrying were performed at 100 ° C. by a kneader coater to obtain a film. A coated carrier having a thickness of 0.25 μm was obtained.

Embodiment 5 Structure No. 20 polycarbonate resins in dimethylformamide with a solid content of 1
0%, and magnetite particles having an average particle size of 40 μm were used as a core material of the carrier. The polycarbonate resin solution was mixed so that the solid content was 1.2 parts by weight with respect to 100 parts by weight of the magnetite particles. The resulting mixture was coated and carried at 150 ° C. by a kneader coater to obtain a coated carrier having a thickness of 0.25 μm.

Embodiment 6 Structure No. Polycarbonate resin No. 23 was dissolved in toluene so as to have a solid content of 10%, and magnetite particles having an average particle size of 50 μm were used as a core material of the carrier. The polycarbonate resin solution was added so as to be 2 parts by weight, and coating and carrying were performed at 100 ° C. with a kneader coater to obtain a coated carrier having a thickness of 0.25 μm.

Embodiment 7 Structure No. 28. Is dissolved in toluene so as to have a solid content of 10%, and magnetite particles having an average particle size of 50 μm are used as a core material of the carrier. The solid content weight is 1.2 to 100 parts by weight of the magnetite particles. The polycarbonate resin solution was added so as to be in parts by weight, and coating and carrying were performed at 90 ° C. with a kneader coater,
A coated carrier having a thickness of 0.25 μm was obtained.

[Comparative Example 1] In Example 2, a polycarbonate resin was used as a starting material to prepare a polyperfluorophenyl carbonate resin [weight average molecular weight (Mw) 70,000, gel permeation chromatography (GPC) value]
Except for using, the same treatment as in Example 2 was performed to obtain a carrier into which the silane coupling agent was not inserted.

Comparative Example 2 Instead of the polycarbonate resin in Example 6, a polybisphenol A carbonate resin [weight average molecular weight (Mw) 60,000, gel permeation chromatography (GPC) value] was used for the core material. A carrier was obtained in the same manner as in Example 6, except that the used Cu-Zn-based ferrite particles having an average particle diameter of 50 µm were coated with 3-aminopropyltrimethoxysilane.

(Preparation of Toner for Measurement) Linear polyester resin 100% by weight (Linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol; Tg = 62 ° C., Mn = 4,000, Mw) = 35,000, acid value = 12, hydroxyl value = 25) Magenta pigment (CI Pigment Red 57) 3% by weight The above mixture was kneaded with an extruder, pulverized with a jet mill, and then air-classified. Classification was performed using a press to obtain magenta toner particles having d ₅₀ = 8 μm.

(Evaluation) A developer was prepared by mixing 8 parts by weight of the above magenta toner with 100 parts by weight of the carriers obtained in Examples and Comparative Examples, and an electrophotographic copying machine (Fuji Xerox Co., Ltd., A- Color630) and a copy test was performed. Table 8 shows the results. Table 8
The charge amount is a value obtained by image analysis of CSG (charge spectrograph method).

[0055]

[Table 8]

As is clear from Table 8, all the developers using the carriers of the examples produced images free from fog and density unevenness. These images also had stable image densities of around 1.3, and exhibited a stable toner charge amount even with environmental changes. Further, regarding the carrier coating material peeling, the carrier surface after 10,000 copies was observed with an electron microscope. As is clear from Table 8, the carrier coating material peeling was not observed, and the carrier coating material was not externally added. No adhesion of the agent or the toner component was observed.

On the other hand, in the case of the developer using the carrier of Comparative Example 1, density unevenness was observed. In the case of the developer using the carrier of Comparative Example 2, an image free of fog and density unevenness was obtained, but the toner charge amount was low and the toner was unstable against environmental fluctuations. Further, the charge amount of the toner after 10,000 copies has been considerably reduced in both Comparative Examples 1 and 2.
When the carrier surface of Comparative Example 1 and Comparative Example 2 was observed with an electron microscope after 10,000 copies, peeling of the carrier coating material was observed in part, and embedding of an external additive into the carrier surface (the charge amount of the toner). (Observed as a decrease) and adhesion of toner components.

[0058]

According to the present invention, it is possible to provide a carrier for electrostatic charge development having excellent adhesion to a core material, abrasion resistance, and contamination resistance by employing the above-mentioned structure. The present invention shows a stable charge-providing ability even when the toner changes for a long time or is used continuously for a long time, and makes it possible to provide a good image without unevenness and fogging of the image.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Horiuchi Kazunaga 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (3)

[Claims] 1. A carrier for developing an electrostatic latent image, comprising a core material having a resin coating layer containing a polycarbonate compound represented by the following general formula (1). Embedded image 2. An electrostatic latent image developer comprising the carrier according to claim 1 and a toner. 3. An image forming method for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on a developer carrier, wherein the developing is performed using the developer according to claim 2. An image forming method comprising: