JP3127331B2 - Electrophotographic carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic carrier constituting an electrostatic charge developer together with a toner.

[0002]

2. Description of the Related Art U.S. Pat.
No. 7,691, Japanese Patent Publication No. 42-24748 and Japanese Patent Publication No. 43-24748, etc., various methods are described. In any of these methods, a photoconductive layer is formed on a photoconductive layer according to an original. An electrostatic latent image is formed by irradiating the image, and then a fine colored powder called toner having the opposite polarity is deposited on the electrostatic latent image, and the electrostatic latent image is developed. After the transfer of the toner image onto a transfer material such as paper, the toner image is fixed by heat, pressure, solvent vapor or the like to obtain a copy.

In the process of developing the electrostatic latent image, toner particles charged to a polarity opposite to that of the latent image are attracted by electrostatic attraction and adhered on the electrostatic latent image (reversal development). In the case of (1), a toner having a triboelectric charge of the same polarity as the latent image is used). Generally, a method of developing such an electrostatic latent image using the toner is roughly classified into a so-called two-component method in which a small amount of toner is dispersed in a medium called a carrier. A method using a system developer,
There is a method using a so-called one-component developer which uses toner alone without using a carrier.

In general, carriers constituting such a two-component developer are roughly classified into conductive carriers and insulating carriers.

[0005] Oxidized or unoxidized iron powder is usually used as the conductive carrier. However, in a developer containing the iron powder carrier as a component, the triboelectric charging property with respect to the toner is unstable. There is a problem that fogging occurs in the formed visible image. That is, with the use of the developer, the toner particles adhere to the surface of the iron powder carrier particles, so that the electric resistance of the carrier particles increases, the bias current decreases, and the triboelectrification becomes unstable. The image density of the visible image decreases and fog increases.

[0006] A typical example of the insulating carrier is a carrier obtained by uniformly covering the surface of a carrier core material made of a ferromagnetic material such as iron, nickel, or ferrite with an insulating resin. In a developer using this carrier,
There is an advantage that the toner particles are less likely to fuse to the surface of the carrier as compared with the case of the conductive carrier, and have excellent durability and a long service life, which is particularly suitable for a high-speed electronic copying machine.

However, in this insulating carrier, the coating layer covering the surface of the carrier core material has sufficient abrasion resistance and strong adhesiveness with the core material (durability), and the carrier has a toner layer. That the coating layer has good anti-sticking properties so that a film is not formed by the toner (toner spent property), and that a charged state of a desired polarity can be obtained by friction with a specific toner used with the carrier. (Chargeability) is required. That is, the carrier is rubbed with other carrier particles and toner particles in the developing device, but when the toner adheres to the surface of the carrier coating layer to form a film, the charging characteristics become unstable.

[0008] In order to prevent such spent, there has been proposed a method of coating the carrier surface with various resins, but no satisfactory resin has been obtained.

For example, a carrier coated with a fluorocarbon resin such as an ethylene tetrafluoride copolymer has a low critical surface tension, so that it is difficult for the toner to be spent. However, the film forming property is poor, and the carrier core material is sufficiently uniform. It cannot be coated and stable charging characteristics cannot be obtained. In addition, the adhesiveness to the core material is weak, and the wear resistance is unsatisfactory. Further, from the relationship with the charging series, the fluorine-based resin-coated carrier is
In the negative charging characteristic, it cannot have a sufficient charging ability.

On the other hand, a carrier coated with an acrylic resin such as a styrene-methacrylate copolymer has good film-forming properties and good adhesion to a carrier core material. However, the styrene-acrylic polymer has a relatively high critical surface tension, and the spent toner is relatively liable to be spent when repeatedly used, and there is a slight problem in the life of the developer. Further, from the viewpoint of wear resistance, it cannot be said that the surface hardness is sufficient even though the surface hardness is relatively high.

Also, silicone resin is known to have low surface energy and reduce spent, but the mechanical strength of the silicone resin itself is weak, and the coating layer is worn away while stirring in a developing device, It was difficult to stabilize the charging characteristics. It is also possible to use a polymer compound having a polydialkylsiloxane structural unit mixed with another polymer such as a styrene-acrylic copolymer, but in this case, a polymer compound containing the mixed polydialkylsiloxane is also used. Since the polydialkylsiloxane is concentrated on the surface, the polydialkylsiloxane structural unit is lost due to abrasion during stirring in the developing device, and it has been difficult to stabilize the charging characteristics for a long time.

Accordingly, there is a demand for a carrier coating agent which is excellent in toner spent property, high in image quality and excellent in stability while satisfying the charging characteristics required for a carrier of a two-component developing system.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a carrier which gives an image which is extremely stable over a long period of time. Still another object of the present invention is to provide a carrier coated with a highly durable coating agent having sufficient mechanical strength against abrasion and impact. Still another object of the present invention is to provide a coated carrier having excellent surface release of a carrier coating agent, hardly causing spent toner, and having high stability and high image quality.

[0014]

The above-mentioned object of the present invention is achieved by the following general formula [1]:

[0015]

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(Wherein A is a linear, branched or cyclic alkylidene group having 1 to 10 carbon atoms, an aryl substituted alkylidene group, an arylenedialkylidene group, or -O
—, —S—, —CO—, —SO—, and —SO ₂ —, and R _{1 to} R ₄ independently represent hydrogen, halogen, or an alkyl or alkenyl group having 1 to 4 carbon atoms. ) And the following general formula [2]

[0017]

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(Wherein, R ₅ is an alkylene or alkylidene group having 2 to 6 carbon atoms, and R ₆ and R ₇ are 1 to 3 carbon atoms.)
Alkyl groups, phenyl groups or substituted phenyl groups, and n represents an integer of 1 to 200. ), Wherein the structural unit represented by the general formula [2] is contained in an amount of from 0.1 to 100% by weight based on the total weight of the copolymer.
This is achieved by an electrophotographic carrier characterized in that it is coated with 50% by weight of a copolymer.

That is, the copolymer according to the present invention has the following general formula [3]

[0020]

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(R _{1 to} R ₇ are the same as above. M + n = 10
0, n = 0.1 to 50)
It is a polydiorganosiloxane block copolymer.

[0022] Polycarbonate resins are generally known to have excellent impact resistance and good film-forming properties, but the surface releasability is poor. , And the charging characteristics were remarkably reduced, making it difficult to continuously obtain a carrier coating having stable charging characteristics.

Various proposals have been made to improve the toner spent property of the polycarbonate resin described above.
For example, a polycarbonate copolymer obtained by copolymerizing a polyorganosiloxane has been proposed. However, conventional polyorganosiloxane copolymerized polycarbonate resins cannot form a homogeneous copolymer because it is difficult to synthesize with good uniformity when synthesizing the copolymer, and as a result, There was a disadvantage that the strength of the cast film was significantly reduced.

Therefore, the present invention improves on the above-mentioned drawbacks,
In order to provide a highly durable and highly stable developer composition, a block copolymer polycarbonate resin which improves surface releasability and does not reduce the film strength is used as a carrier coating resin.

That is, in the present invention, a polydialkylsiloxane structural unit is copolymerized sufficiently uniformly with a polycarbonate resin which is originally known to have good impact resistance, whereby the polydialkylsiloxane structural unit is introduced into the resin itself. And imparts surface lubricity while maintaining impact resistance.

By using the above-mentioned polycarbonate resin as a carrier coating agent, the releasability of the carrier coating is improved, so that it is possible to remarkably prevent a decrease in carrier life due to toner spent or the like. Further, the resin coating solution can be homogenized to prevent a decrease in the strength of the carrier coating layer, and as a result, it is possible to provide a developer composition having improved durability and high durability and high stability.

That is, the copolymer of the present invention becomes a transparent solution when dissolved in a solvent, and can form a sufficiently strong resin film to form a good resin film. This is because when the copolymerization reaction is carried out using the dialkylsiloxane block diphenol compound represented by the general formula [2] used in the present invention, the polymerization is carried out sufficiently at random, and therefore the long-chain polydialkylsiloxane block is obtained. It is presumed that there is no occurrence of white turbidity due to the decrease in solubility or the decrease in compatibility due to growth of. In addition, a copolymer containing only polydialkylsiloxane has stable characteristics without being simultaneously formed.

The carrier of the present invention can be obtained by coating a carrier core material with the above-mentioned polycarbonate resin. In the step of obtaining the resin-coated carrier of the present invention, first, a polycarbonate-polydialkylsiloxane copolymer represented by the general formula [3] serving as a base is treated with a suitable solvent, specifically, an aromatic solvent such as benzene, toluene, or xylene. Group solvents, dichloromethane, trichloroethane, halogen compounds such as chlorobenzene, and tetrahydrofuran,
It is dissolved in cyclic ethers such as tetrahydropyran and dioxane, applied to a core material, dried after forming a coating film to form a resin coating.

The copolymer of the present invention is synthesized by a polymerization method such as a phosgene method, a transesterification method, or a method involving chloroformate. In order to stably reproduce the randomness of the copolymer, the copolymer in a solution is required. Those formed by a polymerization method using the phosgene method are preferred. Specific examples of the method for producing such a block polycarbonate resin include a method described in JP-A-48-64199.

Specific examples of the diphenol compound that can be used to obtain the polycarbonate-polyorganosiloxane copolymer of the general formula [3] of the present invention include the following.

[0031]

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[0032]

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[0033]

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[0034]

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Among the above-mentioned compounds, particularly exemplified compound N
o. 3, 8, 16, 19 and 21 are preferred.

Next, specific examples of the polyorganosiloxane used in the present invention will be shown, but the present invention is not limited thereto. Exemplified Compound No.

[0037]

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The copolymerization ratio in the general formula [3] is determined based on the weight ratio of the monomer which gives the structural unit represented by the general formula [2] in terms of the mechanical strength and the impact resistance of the copolymer. (Substantially the same as the weight ratio in the composition) 0.1 to 5
It is preferably in the range of 0% by weight. This ratio is 0.1
When it is smaller, the mechanical strength is insufficient and the durability is reduced. When it exceeds 50, the durability and the charging stability after repeated use are reduced.

The polycarbonate copolymer represented by the general formula [3] preferably has a molecular weight of 10,000 to 100,000 in terms of weight average molecular weight. If the molecular weight is smaller than 10,000, the durability is deteriorated. If the molecular weight is larger than 100,000, the viscosity becomes too high when coating the core material, and it is difficult to coat the resin with a predetermined coating amount. .

The carrier of the present invention is prepared by dissolving the above-described block polycarbonate resin in a suitable solvent, specifically, for example, a solvent such as dichloromethane, and using this solution as a carrier coating solution, a coating machine (Spira Coater, Okada Seiko Co., Ltd.) Formed on a ferrite carrier having an average particle size of 70 μm. After application, 70-8
After pre-drying at 0 ° C. to evaporate the solvent, 120 to 16
Heat treatment is performed at 0 ° C. for 0.5 to 1 hour. The resin coating amount of the resin-coated carrier can be appropriately selected so as to satisfy desired durability and charging characteristics, and is usually preferably in the range of 0.01 to 30% by weight based on the carrier core. If it is less than 0.05% by weight, the effect of covering the carrier core material is not sufficient.

The resin coating amount here depends on the true specific gravity of the core material, and when the true specific gravity of the carrier is set to Z, the optimum value of the resin coating amount is in the range shown by the following equation.

1 / 2Z ≦ Resin coating amount ≦ 50 / Z (% by weight) More preferably, 1 / Z ≦ Resin coating amount ≦ 25 / Z (% by weight).

The carrier core material used in the present invention comprises iron,
Commonly used materials such as ferrite can be used.
The average particle size of the carrier particles of the present invention is 5 to 100.
Those having a range of μm are preferred. Carrier particle size is 5μm
If it is less than 100 μm, the carrier tends to adhere to the photoreceptor, and if it exceeds 100 μm, the share of the developer in the developing device becomes large, and the deterioration of the developer, especially the peeling of the external additive of the toner particles, It tends to cause shape change. Furthermore, when the particle size is large, the specific surface area is small, so that the amount of toner that can be held when constituting the developer is small, and an image lacking in definition is obtained. The particle diameter of the carrier used in the present invention was obtained by randomly extracting 300 or more carriers by an optical microscope, and using the image processing and analysis apparatus Luzex3 manufactured by Nireco Co., Ltd. to obtain the carrier particle diameter as the horizontal Feret diameter.

The resistance value of the coated carrier used in the present invention is preferably in the range of 10 ⁸ to 10 ¹⁴ Ωcm. In the present invention, the method of measuring the electric resistance can be exemplified by the method of measuring by the method of FIG. That is, generally, the electric resistance of the carrier is the device shown in FIG. 1, the cell A is filled with the carrier, the electrodes 1 and 2 are arranged so as to be in contact with the filled carrier, and a voltage is applied between the electrodes. The minute current flowing at that time is measured, and the specific resistance ρ (Ωcm) is determined from this. However, the carrier is a powder, and therefore the carrier may vary depending on the filling rate, so that the measurement requires care. The resistance value of the carrier measured by the above-described method can be measured not only in the case of the carrier core alone, but also in a state where the carrier is covered, and in any case, the carrier itself is measured by the above-described measurement method. It is required to have a predetermined resistance value when performed. The conditions for measuring the specific resistance in the present invention were as follows: the contact area S between the charged carrier and the electrode was about 2.3 cm ² , the thickness was about 1 mm, the load on the upper electrode 2 was 275 g, and the applied voltage was 100 V.

The amount of triboelectric charging of the coated carrier in the present invention with respect to the toner is preferably in the range of 5 to 50 μC / g. The method of measuring the triboelectric charge amount of the carrier with respect to the toner in the present invention will be described in detail with reference to FIG.

FIG. 2 is an explanatory view of a device for measuring the amount of triboelectric charge. A magnetic brush (toner and toner) on a developer carrier whose frictional charge is to be measured is measured in a metallic measuring container 22 having a conductive screen 23 of 500 mesh (which can be appropriately changed to a size that does not allow the passage of carrier particles) at the bottom. (Mixture of magnetic particles), and the metal lid is weighed to obtain W ₁ (g). Next, in the suction device 21 (at least a portion in contact with the measurement container 22 is an insulator), the air is adjusted through the suction port 27 to prepare the air volume control valve 26, and the pressure of the vacuum gauge 25 is set to 250 mmHg. In this state, suction is sufficiently performed (about 1 minute) to remove the toner by suction. The potential of the electrometer 29 at this time is set to V (volt). Here, 28 is a capacitor whose capacity is C
(ΜF). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). This triboelectric charge (μC / g) can be calculated as in the following equation.

[0047]

(Equation 1)

However, the measurement conditions were: 23 ° C., 65% RH
And

In the present invention, methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, vinyltris- (methoxyethoxysilane), and vinyltrimethoxysilane are used for the purpose of improving the adhesion at the interface between the coating resin and the carrier core material. Acetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ- (aminoethyl) aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl)
Silane coupling agents such as ethyltrimethoxysilane and γ-chloropropyltrimethoxysilane, specifically, for example, tetraisopropyl titanate, tetraisopropyl titanate polymer, tetrabutyl titanate, tetrabutyl titanate polymer, tetrastearyl titanate, 2-ethylhexyl titanate And organic titanium compounds such as isopropoxytitanium stearate, titanium acetylacetonate, and titanium lactate, and organic phosphoric acid-based adhesion promoters. The above compounds may be used alone or in combination of two or more. Furthermore, the carrier coating agent of the present invention may be applied after previously treating the carrier core with the above-mentioned compound, or the above-mentioned adhesiveness improving agent may be mixed in the coating agent, and applied at once. Good.

The coating resin used in the present invention can be used alone as the block copolymer polycarbonate resin having the structure represented by the general formula [3].
As appropriate, for example, acrylic resin, styrene-acrylic copolymer, ethylene-vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, polyvinyl carbazole resin, phenoxy resin, polycarbonate resin, polyvinyl butyral resin, polystyrene resin, polyvinyl acetate Resin, polyarylate resin,
It may be used as a mixture with a polysulfone resin or the like.

[0051]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by the examples. The percentages and parts in the following formulations are based on weight.

Example 1 A block copolymer polycarbonate resin having the following structural formula

[0053]

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15 parts of (weight average molecular weight: 25,000) were dissolved in 85 parts of tetrahydrofuran to form a coating solution for forming a carrier coating. This solution was applied to a spherical ferrite core having an average particle size of 45 μm using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This is first done at 80 ° C for 20
After preliminarily drying, the resultant was dried at 150 ° C. for 40 minutes to obtain a resin-coated carrier. The resin coating amount of the resin-coated carrier obtained through the above-mentioned drying step was 0.94%, and it was confirmed by observation with an electron microscope that the carrier was well coated.

On the other hand, 100 parts of a polyester resin obtained by condensing propoxylated bisphenol and fumaric acid, 5 parts of a phthalocyanine pigment, 5 parts of a chromium complex of di-tert-butylsalicylic acid, 4 parts, were sufficiently premixed with a Henschel mixer, and then mixed with 3 bottles. The mixture was melt-kneaded three times with a roll mill, cooled, and coarsely ground to a particle size of about 1 to 2 mm using a hammer mill. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to have a weight average particle size of 8.3.
Thus, a negatively chargeable cyan toner having a particle diameter of μm was obtained.

100 parts of the above-described cyan toner and 0.4 parts of fine silica powder hydrophobically treated with hexamethylene disilazane were mixed with a Henschel mixer to prepare a cyan toner having fine silica powder on the surface of toner particles.

This cyan toner and the above-mentioned carrier were mixed under a temperature / humidity environment of N / N (23 ° C./60% RH) so that the toner concentration became 15% to obtain a developer. 100 g of the obtained developer was placed in a 250 cc plastic bottle, and shaken with a Turbula mixer at normal temperature and normal humidity for 1 hour. Thereafter, the developer was taken out, and the developer was observed with an electron microscope. As a result, no peeling of the coating agent from the carrier and no filming by the toner were observed.

Further, using this developer, a full color laser copying machine CLC-500 manufactured by Canon was modified, and an image output test was conducted.

As a result, a clear image was obtained in which the density of the solid image was sufficiently high and there was no fog in the non-image portion and no roughness in the halftone portion. Also, set the developing unit to 200 rpm
The idle rotation was performed at the speed of 40 minutes. After that, the image was re-examined and a good result was obtained with no roughness in the halftone portion.

Table 1 shows the obtained results.

Example 2 Block copolymer polycarbonate resin having the following structural formula

[0062]

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15 parts of (weight average molecular weight: 15,000) were dissolved in 85 parts of dioxane to form a coating solution for forming a carrier coating. This solution was applied to a ferrite core having an average particle size of 45 μm previously treated with methyltrimethoxysilane using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This is first pre-dried at 80 ° C. for 20 minutes,
After drying at 40 ° C. for 40 minutes, a resin-coated carrier was obtained. The resin coating amount of the resin-coated carrier obtained through the above-described drying step was 0.95%, and it was confirmed by observation with an electron microscope that the carrier was well coated.

When this was evaluated in the same manner as in Example 1, good results were obtained. Table 1 shows the results.

Example 3 Block copolymer polycarbonate resin having the following structural formula

[0066]

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(Weight average molecular weight 45,000)
And 1 part of tetraisopropyl titanate were dissolved in 85 parts of tetrahydrofuran to form a coating solution for forming a carrier coating. This solution was applied to a ferrite core having an average particle size of 50 μm using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This was first preliminarily dried at 80 ° C. for 20 minutes, and then dried at 150 ° C. for 40 minutes to obtain a resin-coated carrier. The resin-coated carrier obtained through the above-mentioned drying step had a resin coating amount of 0.91%, and was observed to be well coated by observation with an electron microscope.

When this was evaluated in the same manner as in Example 1, good results were obtained. Table 1 shows the results.

Example 4 Block copolymer polycarbonate resin having the following structural formula

[0070]

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15 parts of (weight average molecular weight of 30,000) was dissolved in 85 parts of dioxane to form a coating solution for forming a carrier coating. This solution was applied to a ferrite core having an average particle size of 50 μm using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This was first pre-dried at 80 ° C. for 20 minutes, and then dried at 150 ° C. for 40 minutes to obtain a resin-coated carrier. The resin coating amount of the resin-coated carrier obtained through the above-mentioned drying step was 0.90%, and it was confirmed by observation with an electron microscope that the carrier was well coated.

When this was evaluated in the same manner as in Example 1, good results were obtained. Table 1 shows the results.

Example 5 Block copolymer polycarbonate resin having the following structural formula

[0074]

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(Weight average molecular weight 25,000)
And 1 part of methyltriethoxysilane were dissolved in 85 parts of dioxane to form a coating solution for forming a carrier coating. This solution was applied to a ferrite core having an average particle size of 50 μm using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This is first pre-dried at 80 ° C for 20 minutes, and then
After drying for 0 minutes, a resin-coated carrier was obtained. The resin coating amount of the resin-coated carrier obtained through the above-mentioned drying step is 0.1.
It was 90%, and it was confirmed that the film was well coated by observation with an electron microscope.

When this was evaluated in the same manner as in Example 1, good results were obtained. Table 1 shows the results.

Example 6 Block copolymer polycarbonate resin having the following structural formula

[0078]

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15 parts of (weight average molecular weight 28,000) was dissolved in 85 parts of tetrahydrofuran to form a coating liquid for forming a carrier coating. This solution was applied to a ferrite core having an average particle size of 50 μm using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This was first pre-dried at 80 ° C. for 20 minutes, and then dried at 150 ° C. for 40 minutes to obtain a resin-coated carrier. The resin coating amount of the resin-coated carrier obtained through the above-mentioned drying step was 0.90%, and it was confirmed by observation with an electron microscope that the carrier was well coated.

When this was evaluated in the same manner as in Example 1, good results were obtained. Table 1 shows the results.

Example 7 Block copolymer polycarbonate resin having the following structural formula

[0082]

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15 parts of (weight average molecular weight 95,000) was dissolved in 95 parts of chlorobenzene to form a coating solution for forming a carrier coating. This solution was applied to a ferrite core having an average particle size of 50 μm using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). This was first pre-dried at 80 ° C. for 20 minutes, and then dried at 150 ° C. for 40 minutes to obtain a resin-coated carrier. The resin coating amount of the resin-coated carrier obtained through the above-mentioned drying step was 0.90%, and it was confirmed by observation with an electron microscope that the carrier was well coated.

When this was evaluated in the same manner as in Example 1, good results were obtained. Table 1 shows the results.

Comparative Example 1 Acrylic copolymer having the following composition Styrene-2-ethylhexyl methacrylate copolymer (copolymerization ratio 40/60) Weight average molecular weight 30,000
(Equivalent to polystyrene using gel permeation chromatogram) A resin-coated carrier was formed and evaluated in the same manner as in Example 1 except for using a gel permeation chromatogram. Spent of toner was confirmed. After the durability test was performed in the same manner as in Example 1, fog in the non-image area was observed, and an unclear image with halftone roughness was obtained.

Comparative Example 2 Polycarbonate-siloxane copolymer having the following composition

[0087]

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A resin-coated carrier was formed and evaluated in the same manner as in Example 1 except that (weight average molecular weight: 20,000) was used. As a result, good results were obtained with respect to toner spent and the like. However, image quality was severely degraded after the durability test by idle rotation of the developing device. This is because the coating strength of the resin coating layer was not sufficient, and the coating resin layer was missing with the progress of durability.

[0089]

[Table 1]

[0090]

According to the present invention, by using the siloxane block copolymerized polycarbonate resin of the present invention as a coating material for a resin-coated carrier, excellent toner spent properties and high image quality can be provided over a long period of time from the beginning. It has become possible to provide a durable, highly stable and long-lasting resin-coated carrier.

[Brief description of the drawings]

FIG. 1 is a schematic diagram schematically showing an apparatus for measuring the specific resistance of a carrier.

FIG. 2 is a schematic view schematically showing an apparatus for measuring the triboelectric charge of a toner of a two-component developer. DESCRIPTION OF SYMBOLS 1 Lower electrode 2 Upper electrode 3 Insulator 4 Ammeter 5 Voltmeter 6 Constant voltage device 7 Sample (carrier) 8 Guide ring A Measurement cell 21 Aspirator 22 Measurement container 23 Conductive screen 24 Lid 25 Vacuum gauge 26 Air volume control valve 27 Suction port 28 Capacitor 29 Electrometer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-48-64199 (JP, A) JP-A-64-32267 (JP, A) JP-A-46-6034 (JP, A) JP-A-2- JP-A-2-239256 (JP, A) JP-A-5-188652 (JP, A) JP-A-64-91144 (JP, A) JP-A-3-1163 (JP, A) JP-A-3-163568 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/10

Claims (5)

(57) [Claims] [Claim 1] The following general formula [1] (Wherein A is a linear, branched or cyclic alkylidene group having 1 to 10 carbon atoms, an aryl-substituted alkylidene group,
Arylenedialkylidene group, or -O-, -S-,
—CO—, —SO—, and —SO ₂ —, and R _{1 to} R
₄ independently represents hydrogen, halogen, or an alkyl or alkenyl group having 1 to 4 carbon atoms. ) And the following general formula [2]: (Wherein, R ₅ is an alkylene group or alkylidene group having 2 to 6 carbon atoms, R ₆ and R ₇ are an alkyl group having 1 to 3 carbon atoms, a phenyl group or a substituted phenyl group, and n is 1 to 3)
Indicates an integer of 200. A) a copolymer having the structural unit represented by the general formula [2], wherein the structural unit represented by the general formula [2] is 0.1 to 50% by weight based on the total weight of the copolymer. An electrophotographic carrier, which is coated. 2. The structure represented by the formula [1] is represented by the following formula: The electrophotographic carrier according to claim 1, wherein 3. The structure represented by the formula [1] is represented by the following formula: The electrophotographic carrier according to claim 1, wherein 4. The structure represented by the formula [1] is represented by the following formula: The electrophotographic carrier according to claim 1, wherein 5. The structure represented by the formula [1] is represented by the following formula: The electrophotographic carrier according to claim 1, wherein