JPH1138683A - Carrier and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a satisfactory carrier not generating an inversely charged toner by dissolving epoxy resin in a solvent, adding a straight-chain aliphatic polyamine and an acid anhydride, mixing them and carrying out heat curing. SOLUTION: Epoxy resin is dissolved in a solvent. Carbon black is added as an electrically conductive agent and they are mixed. A straight-chain aliphatic polyamine such as diethylenetriamine, triethylenetetramine or tetraethylenepentamine and an acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride or trimellitic anhydride are then added as curing agents. The mixture dissolved in the solvent is sprayed to coat the surface of a core (magnetic powder) by fluidized bed coating and hot air drying is carried out. The dried resin on the surface of the magnetic powder is cured by heating. Even when the heat curing is carried out in a stationary state, blocking is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carrier having a magnetic powder surface coated with an epoxy resin and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a carrier for an electrophotographic developer is mixed with a toner and mounted on a unit called a developing device such as a copying machine or a printer. While the toner is developed on the photoreceptor and is a powdered ink that is transferred and fixed on the paper, the carrier literally plays the role of transporting it, and on the magnet roll of the developing device, it has a shape called a magnetic brush, It functions as a so-called brush for applying toner on the photoconductor. On the other hand, it is also used for the purpose of giving a proper electrostatic force to toner.

[0003]

An epoxy resin is a resin having a functional group called an epoxy group, an oxysilane group or an ethoxyline group. When cross-linked and polymerized by using a curing agent, general adhesive properties and mechanical properties are obtained. Gives an excellent cured product. Most commercially available epoxy resins have a molecular weight of 100
Since it has a low degree of polymerization of less than 00 and does not provide sufficient strength when used alone, it is used in combination with a curing agent. There are two types of curing agents: those that cure sufficiently at room temperature, and those that require long-time heating at high temperatures.
As a representative of the type that cures sufficiently at room temperature, there are linear aliphatic polyamines such as diethylenetriamine, triethylenetetramine and tetraethylenepentamine,
Each of these is a polar group showing strong positive chargeability, NH
Having _two groups, when unreacted components remain in the carrier coating component and precipitate on the surface, when mixed with a positively chargeable toner and used as a developer, a reversely charged toner is generated, causing printing fog. To get enough strength,
Ideally, a curing agent equivalent to the epoxy group of the epoxy resin is added.However, if the amount of the linear aliphatic polyamine added is close to the epoxy group and the equivalent, the risk of unreacted components remaining increases. There has been a problem that a device having stable and appropriate charging characteristics cannot be obtained.

Further, acid anhydrides such as phthalic anhydride, tetrahydrophthalic anhydride and trimellitic anhydride do not have a positive functional group and do not have a problem like a linear fatty acid polyamine, but have a very long time. It is necessary to heat and cure at high temperature. Low-molecular-weight epoxy resin has a low softening temperature. If the resin is coated on the surface of the magnetic powder and then subjected to heat-curing treatment in a standing state, the resin is fused and formed into a block before the curing reaction proceeds. . When coating is performed using a fluidized bed, the magnetic particles are suspended with hot air, the coating liquid is sprayed on the surface of the magnetic particles, and the coating is formed while drying the solvent with hot air. As a result, the powder was atomized, but it turned into powder before the coating liquid reached the particle surface, and there was a danger of explosion of the organic solvent. Then, there was a problem that hardening hardly progressed.

On the other hand, high molecular weight epoxy resins with advanced glycidyl ether bonds have a high softening temperature and high strength, but have poor solubility in solvents, and the high molecular weight components are not stirred unless heated for a long time. It does not dissolve and precipitates and sediments. In addition, since the solution viscosity also increases, the fluidized bed method,
When coating is performed by a general electrophotographic developer carrier coating method such as an immersion method, coat unevenness is likely to occur, and a large amount of aggregates are generated. As described above, there is a problem that it is extremely difficult to perform coating using an epoxy resin having a high molecular weight before coating.

[0006] The present invention solves these problems,
Uses a relatively low molecular weight epoxy resin that dissolves easily in a solvent and does not increase the viscosity of the coating solution. High temperature, requires long-term heating, but adds and mixes both acid anhydride curing agents that do not contain a positively chargeable component, coats using a fluidized bed, and coats at a temperature of 100 ° C. or less in the coating process. However, the melting point rises due to moderate curing, and after that, it does not block even when subjected to heat curing treatment in a static state, and after curing, unreacted components other than acid anhydride remain, so reverse-charged toner is generated The purpose is to produce a good carrier that does not allow it.

[0007]

Means for solving the problem will be described with reference to FIG. 1 as an example. In FIG. 1A, S1
Dissolves an epoxy resin in a solvent.

In step S2, carbon black is added as a conductive agent. S3 mixes. S4 is a curing agent
A linear aliphatic polyamine (eg, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, etc.) and an acid anhydride (eg, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, etc.) are added.

In step S5, the mixture dissolved in a solvent is sprayed by fluidized bed coating to coat the surface of the core (magnetic powder) and dry with hot air. In step S6, the resin coated on the surface of the magnetic powder dried with hot air is cured (cured) by a heat treatment.

In this case, a fluororesin obtained by polymerizing at least one of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene is mixed together.

Accordingly, a relatively low molecular weight epoxy resin which is easily dissolved in a solvent and does not increase the viscosity of the coating solution is used. Both the type aliphatic polyamine and a high temperature and a long heating time are required, but a curing agent of an acid anhydride containing no positively chargeable component is added and mixed, and the mixture is coated using a fluidized bed. Melting point rises because moderate curing proceeds even at a temperature of less than or equal to ° C., after that, it does not block even when subjected to heat curing treatment in a stationary state, after curing, since unreacted components other than acid anhydride remain, It is possible to manufacture a good carrier that does not generate reversely charged toner.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments and operations of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 is a flowchart (part 1) of a manufacturing method according to the present invention. This is an example of a production method when diethylene triamine is used as a linear aliphatic polyamine and phthalic anhydride is used as an acid anhydride.

FIG. 1A shows a flowchart.
Oiled shell epoxy epoxy resin (product name, EP10
04, molecular weight 1600) 2250 g of acetone 2025
0 g to prepare a coating solution (S1).

To this, 225 g of carbon black (Ketjen Black ECP-600JD, manufactured by Ketjen Black International) is mixed (S2), and stirred and dispersed using a ball mill for 16 hours (S3). Further, 125 g of diethylenetriamine and 18 parts of phthalic anhydride
0 g is added and mixed (S4).

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1, average particle size: 65 μm) is coated with hot air at 85 ° C. while feeding (15 ° C.). S5).

This is loaded on a steer spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier to cure (cur).
(S6). FIG. 1B shows the result. Here, after the heat treatment, no blocking was performed.

FIG. 1C shows a conventional example. In the conventional example shown in Comparative Example 1 described later (Comparative Example to which only an acid anhydride (phthalic anhydride) was added), after the heat treatment, the blocking was not performed and the film was not loosened.

As described above, when only an acid anhydride was added as in the conventional example (Comparative Example 1), blocking was not caused after the heat treatment, and the block was not loosened. By adding the polyamine and the acid anhydride together, it was possible to produce a coated, good carrier which did not block after heat treatment.

FIG. 2 is a flowchart (part 2) of the manufacturing method of the present invention. This is an example of a production method in which triethylenetetramine is used together with a linear aliphatic polyamine and tetrahydrophthalic anhydride is used as an acid anhydride.

FIG. 2A shows a flowchart.
Oiled shell epoxy epoxy resin (product name, EP10
07, molecular weight 2900) 2250 g of acetone 2025
0 g to prepare a coating solution (S11).

To this, 225 g of carbon black (Ketjen Black ECP-600JD) manufactured by Ketjen Black International is mixed (S12), and the mixture is stirred and dispersed using a ball mill for 16 hours (S13).
Further, 82 g of triethylenetetramine and 85 g of tetrahydrophthalic anhydride are added and mixed (S14).

Using a fluidized-bed coating device SFC-5 (Freund Corporation), 15 kg of a clean carrier (trade name: CLC-K1 average particle size: 65 μm) manufactured by FDK is coated with hot air at 85 ° C. while blowing it (85 ° C.). 15).

This is loaded on a stere-spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier to cure (cur).
(16). FIG. 2B shows the result. Here, after the heat treatment, no blocking was performed.

FIG. 2C shows a conventional example. In the conventional example shown in Comparative Example 5 (Comparative Example in which only linear aliphatic polyamine (triethylenetetramine) is added) or Comparative Example 4 (Comparative Example in which only linear aliphatic polyamine (diethylenetriamine) is added) described later, After the treatment, it blocked and did not loosen.

As described above, when only the linear aliphatic polyamine is added as in the conventional examples (Comparative Examples 5 and 4),
Although blocking was not observed after the heat treatment, the carrier was not loosened. However, in this example, by adding the linear aliphatic polyamine and the acid anhydride together, a coated good carrier that was not blocked after the heat treatment could be produced.

FIG. 3 shows a flowchart (part 3) of the manufacturing method of the present invention. This is an example of a production method in which tetraethylenepentamine is used as a linear aliphatic polyamine and trimellitic anhydride is used as an acid anhydride.

FIG. 3A shows a flowchart.
Oiled shell epoxy epoxy resin (product name, EP10
07, molecular weight 2900) 2250 g of acetone 2025
0 g to prepare a coating solution (S21).

To this, 225 g of carbon black (Ketjen Black ECP-600JD, manufactured by Ketjen Black International) is mixed (S22) and stirred and dispersed using a ball mill for 16 hours (S23).
Further, 106 g of tetraethylenepentamine and 216 g of trimellitic anhydride are added and mixed (S24).

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1 average particle diameter 65 μm) is coated with hot air of 85 ° C. while feeding it (85 ° C.). S25).

This is loaded on a steer spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier to cure (cur).
(S26). FIG. 3B shows the result. Here, after the heat treatment, no blocking was performed.

FIG. 3C shows a conventional example. In the conventional example shown in Comparative Example 6 (Comparative Example in which only linear aliphatic polyamine (tetraethylenepentamine) is added) or Comparative Example 4 (Comparative Example in which only linear aliphatic polyamine (diethylenetriamine) is added) described below, After the heat treatment, it blocked and did not loosen.

As described above, when only the linear aliphatic polyamine was added as in the conventional examples (Comparative Examples 6 and 4),
Although blocking was not observed after the heat treatment, the carrier was not loosened. However, in this example, by adding the linear aliphatic polyamine and the acid anhydride together, a coated good carrier that was not blocked after the heat treatment could be produced.

FIG. 4 is a flowchart (No. 4) of the manufacturing method of the present invention. This is an example of a production method when diethylene triamine is used as a linear aliphatic polyamine and phthalic anhydride is used as an acid anhydride.

FIG. 4A shows a flowchart.
Oiled shell epoxy epoxy resin (product name, EP10
04, molecular weight 1600) 1350 g and polyvinylidene fluoride-hexafluoropropylene resin (trade name KYNAR2801) 9 manufactured by Elf Atochem Japan
00 g is dissolved in 20250 g of acetone to prepare a coating solution (S31).

225 g of carbon black (Ketjen Black ECP-600JD, manufactured by Ketjen Black International) is mixed with the mixture (S32), and the mixture is stirred and dispersed using a ball mill for 16 hours (S33).
Further, 75 g of diethylenetriamine and 10 g of phthalic anhydride
8 g is added and mixed (S34).

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1, average particle diameter 65 μm) is coated with hot air at 85 ° C. while feeding it ( S35).

This is loaded on a stere spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier to cure (cur).
(S36). FIG. 4B shows the result. Here, after the heat treatment, no blocking was performed.

As described above, in the present embodiment, the epoxy resin is mixed with the fluororesin, and the linear aliphatic polyamine and the acid anhydride are added together. Carrier could be manufactured.

The carriers manufactured in FIGS. 1 to 4 were mixed with a toner for Fujitsu F6722D at a toner concentration of 4.0 wt% to prepare a developer. Fujitsu F
When printing was performed using a 6722D machine, a clear image without fog was obtained. When continuous printing of 50,000 sheets was further performed, no change was observed in the image quality.

Hereinafter, Comparative Examples 1 to 8 which were tested will be described in detail. Comparative Example 1: 2250 g of an epoxy resin made of Yuka Shell Epoxy (product name, EP1004, molecular weight: 1600) is dissolved in 20250 g of acetone to prepare a coating solution.

225 g of carbon black (trade name: Ketjen Black ECP-600JD) manufactured by Ketjen Black International is mixed with the mixture, and the mixture is stirred and dispersed using a ball mill for 16 hours. Further, phthalic anhydride 3
Add 60 g and mix.

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1, average particle diameter 65 μm) is coated with hot air at 85 ° C.

This was loaded on a steer spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier. As a result, the coated powders were fused together in a solid block, and could not be loosened. .

Comparative Example 2: Epoxy resin made from Yuka Shell Epoxy (product name, EP1007, molecular weight 2900) 22
50 g is dissolved in 20250 g of acetone to prepare a coating solution.

225 g of carbon black manufactured by Ketjen Black International (Ketjen Black ECP-600JD) is mixed with the mixture, and the mixture is stirred and dispersed using a ball mill for 16 hours. Further, 170 g of tetrahydrophthalic anhydride is added and mixed.

Using a fluidized bed coating apparatus SFC-5 (Freund Sangyo), 15 Kg of a clean carrier (trade name: CLC-K1 average particle diameter: 65 μm) made of FDK is coated with hot air at 85 ° C.

When this was loaded on a stere-spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier, the coated powders were fused together in a solid block, and could not be loosened. .

Comparative Example 3: Epoxy resin made from oil-based shell epoxy (product name, EP1007, molecular weight 2900) 22
50 g is dissolved in 20250 g of acetone to prepare a coating solution.

225 g of carbon black manufactured by Ketjen Black International (Ketjen Black ECP-600JD) is mixed with the mixture, and the mixture is stirred and dispersed using a ball mill for 16 hours. Further, 432 g of trimellitic anhydride is added and mixed.

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier (trade name: CLC-K1 average particle size: 65 μm) manufactured by FDK is coated with hot air at 85 ° C.

This was loaded on a steer spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier. As a result, the coated powders were fused together in a solid block, and could not be loosened. .

Comparative Example 4: Epoxy resin made from Yuka Shell Epoxy (product name, EP1004, molecular weight 1600) 22
50 g is dissolved in 20250 g of acetone to prepare a coating solution.

To this, 225 g of carbon black (Ketjen Black ECP-600JD, manufactured by Ketjen Black International) is mixed, and the mixture is stirred and dispersed using a ball mill for 16 hours. Further, 250 g of diethylenetriamine is added and mixed.

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1, average particle diameter 65 μm) is coated with hot air at 85 ° C.

This was mounted on a stere spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier. The carrier thus manufactured was mixed with a toner for Fujitsu F6722D at a toner concentration of 4.0 wt% to prepare a developer.

When printing was performed using a Fujitsu F6722D machine, black spot-like print fog occurred on the background portion. Comparative Example 5: A coating liquid is prepared by dissolving 2250 g of an epoxy resin made of Yuka Shell Epoxy (product name, EP1007, molecular weight 2900) in 20250 g of acetone.

225 g of carbon black manufactured by Ketjen Black International (Ketjen Black ECP-600JD) is mixed with the mixture, and the mixture is stirred and dispersed using a ball mill for 16 hours. Further, 164 g of triethylenetetramine is added and mixed.

Using a fluidized bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1, average particle diameter 65 μm) is coated with hot air at 85 ° C.

This was mounted on a steer spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier. The carrier thus manufactured was mixed with a toner for Fujitsu F6722D at a toner concentration of 4.0 wt% to prepare a developer.

When printing was performed using an F6722D machine manufactured by Fujitsu, black spot-like print fog occurred in the background portion. Comparative Example 6: 2250 g of an epoxy resin (product name, EP1007, molecular weight: 2900) made of Yuka Shell Epoxy is dissolved in 20250 g of acetone to prepare a coating solution.

225 g of carbon black manufactured by Ketjen Black International (Ketjen Black ECP-600JD) is mixed and stirred and dispersed for 16 hours using a ball mill. Further, 212 g of tetraethylenepentamine is added and mixed.

Using a fluidized-bed coating apparatus SFC-5 (Freund Corporation), 15 kg of a clean carrier made of FDK (trade name: CLC-K1, average particle diameter 65 μm) is coated with hot air at 85 ° C.

This was loaded on a stere spat and subjected to a heat treatment at 200 ° C. for 2 hours in a drier. The carrier thus manufactured was mixed with a toner for Fujitsu F6722D at a toner concentration of 4.0 wt% to prepare a developer.

When printing was performed using a Fujitsu F6722D machine, black spot-like print fog occurred in the background portion. Comparative Example 7: 2250 g of an epoxy resin (product name, EP1004, molecular weight: 1600) made of Yuka Shell Epoxy is dissolved in 20250 g of acetone to prepare a coating solution.

225 g of carbon black manufactured by Ketjen Black International (trade name: Ketjen Black ECP-600JD) is mixed with the mixture, and the mixture is stirred and dispersed using a ball mill for 16 hours.

Using a fluidized bed coating device SFC-5 (Freund Corporation), 15 Kg of a clean carrier (trade name: CLC-K1 average particle size: 65 μm) manufactured by FDK is coated with hot air at 85 ° C.

The carrier thus manufactured was mixed with a toner for Fujitsu F6722D at a toner concentration of 4.0 wt% to prepare a developer. When printing was performed using a Fujitsu F6722D machine, a clear image without fog was obtained. However, when 50,000 sheets of continuous printing were further performed, black spot-like print fog occurred in the background portion. Observation of the surface of the carrier with a scanning electron microscope revealed remarkable peeling of the coating.

Comparative Example 8: Epoxy resin (product name, EP1010, molecular weight 5500) made of oil-based shell epoxy 22
An attempt was made to dissolve 50 g in 20250 g of acetone, but it was not completely dissolved, and undissolved components were deposited.

[0070]

As described above, according to the present invention,
Uses a relatively low molecular weight epoxy resin that dissolves easily in a solvent and does not increase the viscosity of the coating solution. High temperature, requires long-term heating, but adds and mixes both acid anhydride curing agents that do not contain a positively chargeable component, coats using a fluidized bed, and coats at a temperature of 100 ° C. or less in the coating process. However, the melting point rises due to moderate curing, and after that, it does not block even when subjected to heat curing treatment in a static state, and after curing, unreacted components other than acid anhydride remain, so reverse-charged toner is generated It is possible to manufacture a good carrier that does not cause such a problem.

[Brief description of the drawings]

FIG. 1 is a flowchart (part 1) of a manufacturing method of the present invention.

FIG. 2 is a flowchart (No. 2) of the manufacturing method of the present invention.

FIG. 3 is a flowchart (part 3) of the manufacturing method of the present invention.

FIG. 4 is a flowchart (No. 4) of the manufacturing method of the present invention.

[Explanation of symbols]

 S1, S11, S21, S31: Resin melt S2, S12, S22, S32: Add conductive agent S3, S13, S23, S33: Mix S4, S14, S24, S34: Add hardener S5, S15, S25, S35: Flow Layer coating S6, S16, S26, S36: Heat treatment (cure)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroyuki Sakaguchi 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd.

Claims (10)

[Claims] 1. A carrier obtained by coating a magnetic powder surface with an epoxy resin, applying a solvent to the epoxy resin, the linear aliphatic polyamine, and the acid anhydride, mixing and coating the magnetic powder surface, and then subjecting the carrier to heat treatment. 2. The carrier according to claim 1, wherein the linear aliphatic polyamine is diethylene triamine, triethylene tetramine, or tetraethylene pentamine. 3. The carrier according to claim 1, wherein the acid anhydride is phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, or trimellitic anhydride. 4. The method according to claim 1, wherein a fluororesin obtained by polymerizing at least one of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene is mixed together. That career. 5. The carrier according to claim 1, wherein said carbon black is mixed together. 6. A method for producing a carrier in which the surface of a magnetic powder is coated with an epoxy resin, the method comprising the steps of: adding a solvent to an epoxy resin, a linear aliphatic polyamine and an acid anhydride and mixing the mixture; A method for producing a carrier, comprising: a step of drying with hot air while coating the surface; and a step of curing remaining resin by heat treatment after drying with hot air. 7. The method according to claim 6, wherein the linear aliphatic polyamine is diethylene triamine, triethylene tetramine, or tetraethylene pentamine. 8. The method according to claim 6, wherein the acid anhydride is phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, or trimellitic anhydride. 9. The method according to claim 6, wherein a fluororesin obtained by polymerizing at least one of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene is mixed together. Manufacturing method of such a carrier. 10. The method for producing a carrier according to claim 6, wherein the carbon black is mixed together.