JP2001117286A - Carrier for electrophotographic developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier for an electrophotographic developer which is excellent in the safety of a human body and the environment and which can impart excellent positive electrification characteristics with proper electrification quantity, distribution of the electrification quantity and buildup of electrification to a toner by decreasing the use of a charge controlling agent. SOLUTION: The carrier for an electrophotographic developer is prepared by forming a resin coating layer on the surface of a carrier core material, and the resin coating layer consists of a polymer obtained by polymerization of monomers containing a compound by 1 to 100 wt.% selected from among the group consisting of compounds expressed by general formulae (1), (2) and (3), for example, compounds of formulae (4), (5) and (6). In the formulae, ϕrepresents a phenylene group, naphthylene group or anthranilene group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a carrier for an electrophotographic developer.

[0002]

2. Description of the Related Art In an electrophotographic process, an electrostatic latent image formed on the surface of a photoreceptor is developed using a toner having an opposite charge, and is transferred to a carrier such as paper by a bias electrode. An image is formed by a fixing process such as heating, pressing and the like. The developing methods in the electrophotographic process are classified into a two-component developing method using a developer composed of a toner and a carrier, and a one-component developing method using only a toner.

[0003] In these developing methods, a required characteristic is that when developing an electrostatic latent image formed on the surface of a photoreceptor, a predetermined amount of opposite charge corresponding to the electrostatic latent image is stabilized on the toner. To induce and hold. As a means for inducing a predetermined amount of charge on the toner, a contact / frictional charging mechanism between the carrier and the toner is generally applied,
As a means for imparting these charging characteristics, it is common to mix a charge control agent (CCA) in the toner.
At this time, the charging characteristics required for the toner include:
(1) providing necessary charge polarity and charge amount; (2)
(3) stable charging, (4) less susceptible to environmental influences such as temperature and humidity, (5) colorless, (6) human and environment And that it is safe.

At present, azo dyes, salicylic acid metal complexes, and the like are used as CCA. These CCAs contain heavy metals such as chromium and zinc.
Issues have been raised in terms of human and environmental security.
Further, development of colorless CCA corresponding to colorization is desired also from the problem of coloring by metal. Further, since CCA is a low molecular crystal, it is difficult to finely disperse it in the toner, and when added to the toner, there is a problem that the charge distribution is widened.

On the other hand, in the two-component developing method, a carrier is used as an object which induces contact and frictional charging with toner. Currently, inorganic powders such as iron powder, iron oxide powder, ferrite, glass beads, and alumina are used as carriers.In the case of iron powder, since the electric resistance is low, it is necessary to oxidize the surface, In the case of iron oxide powder, advanced manufacturing techniques are required to control the electric resistance. Also,
In the case of glass beads, there is a problem in mechanical strength, causing problems such as breakage. As a problem common to these carriers, it is difficult to induce a sufficient charge amount,
An excessive amount of CCA must be incorporated into the toner.

On the other hand, a method of coating the surface of the carrier with a resin composition is used for the purpose of improving the charge inducing ability of the carrier and long-term stability. Currently, fluorine resin, silicone resin, polyester resin and the like are used as the coating resin, but a sufficient amount of charge cannot be obtained, or during long-term use, the coating resin peels off and is stable. Problems such as an inability to obtain a charge amount occur.

[0007]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to reduce the use of a charge control agent (CCA), thereby providing excellent safety to humans and the environment, and an appropriate charge amount and charge for toner. An object of the present invention is to provide a carrier for an electrophotographic developer capable of imparting excellent positive charging characteristics such as an amount distribution and charging rise.

[0008]

The present invention provides a carrier for an electrophotographic developer having a resin coating layer on the surface of a carrier core material, wherein the resin coating layer is represented by the following general formula (1). A compound represented by the following general formula (2):
And an electron comprising a polymer obtained by polymerizing a monomer containing 1 to 100% by weight of at least one compound selected from the group consisting of compounds represented by the following general formula (3). It is a carrier for photographic developer.

[0009]

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In the formula, R represents a hydrogen atom or a methyl group;
X ¹ represents a (substituted) alkylene group having 1 to 18 carbon atoms, a (substituted) phenylene group, a (substituted) naphthylene group, or a (substituted) anthranylene group; and X ² represents a (substituted) alkyl group having 1 to 16 carbon atoms. A (substituted) phenyl group, a (substituted) naphthyl group, or a (substituted) anthranyl group.

[0011]

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Where R¹ Represents a hydrogen atom or a methyl group
Then R^Two Is a (substituted) alkylene group having 0 to 2 carbon atoms, -C
OO-, -O-, -CO-, -NH-CO-, -NR^Three 
− (R^ThreeRepresents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
), -OCO- or (substituted) phenylene groups
Then X¹ Is a (substituted) alkylene group having 1 to 16 carbon atoms,-
(R ^Four O)_n − (R^Four Represents an alkyl group having 1 to 2 carbon atoms.
And n represents 1 to 10), (substituted) phenylene group,
(Substituted) naphthylene group or (substituted) anthranylene
X represents a group^Two Is a (substituted) alkyl having 1 to 16 carbon atoms
Group, (substituted) phenyl group, (substituted) naphthyl group, or
Represents a (substituted) anthranyl group, and φ represents (substituted) phenyle
Group, (substituted) naphthylene group, or (substituted) anthra
Represents a nylene group.

[0013]

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In the formula, R represents a hydrogen atom or a methyl group;
X represents a (substituted) alkyl group having 1 to 18 carbon atoms, a (substituted) phenyl group, a (substituted) naphthyl group, or a (substituted) anthranyl group. In this specification, "(substitution)"
Means that it may have a substituent. Hereinafter, the present invention will be described in detail.

In the carrier for an electrophotographic developer according to the present invention, a compound represented by the following general formula (1), a compound represented by the following general formula (2), and a compound represented by the following general formula ( It has a resin coat layer composed of a carrier coat resin which is a polymer obtained by polymerizing at least one compound selected from the group consisting of the compounds represented by 3). Examples of the compound represented by the general formula (1) include the following compounds.

[0016]

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Examples of the compound represented by the above general formula (2) include the following compounds.

[0018]

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The compound represented by the above general formula (3) includes, for example, the following compounds.

[0020]

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The monomer constituting the carrier coating resin is a compound represented by the following general formula (1), a compound represented by the following general formula (2), and a compound represented by the following general formula (3). At least one selected from the group consisting of compounds
It contains from 1 to 100% by weight of certain compounds. If it is less than 1% by weight, a sufficient charge amount cannot be secured. If it exceeds 70% by weight, it is likely to be affected by temperature and humidity, making it difficult to obtain a stable charge amount. Preferably it is 5-70% by weight.

The monomers constituting the carrier coating resin may contain other monomers, and examples of the other monomers include styrene derivatives, (meth) acrylic acid, (meth) acrylate and the like. Can be That is, the carrier coating resin may contain 99 to 0% by weight of a styrene derivative, (meth) acrylic acid, or (meth) acrylate as a monomer.

The styrene derivative may be one obtained by adding a substituent to styrene, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, and p-methylstyrene.
Chlorostyrene, chloromethylstyrene and the like can be mentioned. The (meth) acrylate is not particularly limited, and examples thereof include methyl (meth) acrylate and (meth) acrylate.
Examples include ethyl acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and stearyl (meth) acrylate.

When the carrier coating resin is a copolymer, the polymerization form is not particularly limited, and may be a polymerization form such as random, block or graft.

The weight average molecular weight of the resin for the carrier coating is preferably 1,000 to 500,000. When the weight average molecular weight is less than 1,000, the obtained carrier is inferior in environmental resistance, and it may be difficult to impart a stable charge amount to the toner. When the weight average molecular weight exceeds 500,000, the obtained carrier may be obtained. Separation of the carrier coating resin is likely to occur. More preferably, it is 3000 to 200,000.

The method for polymerizing the carrier coating resin is not particularly limited, and examples thereof include bulk polymerization, solution polymerization, and suspension polymerization. The polymerization initiator used in the polymerization of the resin for carrier coating is not particularly limited as long as it is used in ordinary radical polymerization.Examples include benzoyl peroxide, lauroyl peroxide, orthochlorobenzoic acid, and orthomethoxy peroxide. Benzoyl, 3,5,5
Organic peroxides such as trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide; azobisisobutyronitrile, azobiscyclohexacarbonitrile, azobis ( Azo compounds such as 2,4-dimethylvaleronitrile); and persulfide initiators such as potassium persulfate. These may be used alone or in combination of two or more.

The carrier for an electrophotographic developer of the present invention can be obtained by dissolving the above-mentioned resin for carrier coating in a good solvent for the resin and then coating the surface of the carrier. The good solvent is not particularly limited, for example, toluene,
THF, DMF and the like. These may be used alone or in combination of two or more. The carrier coating resin may contain another resin as needed. The other resin is not particularly limited,
For example, polystyrene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, fluororesin, silicone resin, and copolymers thereof can be used.

Examples of the carrier core material include iron powder, iron oxide powder, magnetic powder such as ferrite and nickel, glass beads, silica and the like. The particle size of the carrier core material is preferably 20 to 300 μm. 20
If it is less than μm, the fluidity of the developer is reduced, and a load may be applied to the stirrer. In addition, the carrier may jump to the photoconductor, and the photoconductor and the fixing roller may be damaged. 30
When the thickness exceeds 0 μm, the surface area of the carrier decreases, fogging occurs, the image quality may be coarse, the resolution may decrease,
Problems such as a decrease in image density may occur. More preferably, it is 50 to 100 μm.

[0029]

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

(1) Production of Carrier Coating Resin The ingredients shown in Table 1 below were placed in a 3 L four-neck separable flask equipped with a stirrer, and nitrogen was introduced.
The temperature was raised to 0 ° C., and the reaction was performed for 10 hours. After completion of the reaction, THF was distilled off at 100 ° C. under reduced pressure. The resulting polymer was washed with methanol and toluene, filtered, and then dried at 120 ° C. under reduced pressure. The weight average molecular weight and the number average molecular weight of the obtained copolymer were measured by GPC (gel permeation chromatography).
The results are shown in Table 1. GPC measurement conditions: apparatus GPC-201D (3) (W
Columns TSK-gel-α-M (manufactured by Tosoh Corporation) Solvent Dimethylformamide Flow rate 0.8 mL / min Temperature 23 ° C. The monomers A and B in Table 1 are the following compounds.

[0031]

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(2) Manufacture of Carrier Resin 100 for Carrier Coating Obtained as Above
g was dissolved in 800 g of THF, 1 kg of iron powder having a particle size of 200 μm was dispersed, stirred in a boat mill for 1 hour, dried with a dryer and classified to obtain a carrier. Also,
As a comparative example, a carrier that was not subjected to a coating treatment was used.

(3) Measurement of Dispersibility and Charging Performance 6 g of toner (particle size: 8 μm) having the following composition and the carrier 9
After stirring for 4 minutes, the triboelectric charge (μC / g) was measured using a blow-off charge amount measuring device manufactured by Toshiba Chemical Corporation. The results are shown in Table 1.

Binder resin: St / MMA / BA = 75/10/15 87 parts by weight Mw = 1114900, Mn = 6090, Tg = 65 ° C. (manufactured by Sekisui Chemical Co., Ltd.) Carbon black: MA-100 (manufactured by Mitsubishi Chemical Corporation) 8 parts by weight Wax: Viscol 660P (manufactured by Sanyo Chemical Industries) 4 parts by weight Charge control agent: Spiron Black TRH (manufactured by Hodogaya Chemical Industry) 1 part by weight

[0035]

[Table 1]

[0036]

According to the present invention, a charge control agent (CCA)
By reducing the use of, it is excellent in safety for humans and the environment, and the charge amount, charge amount distribution,
As a result, a resin-coated carrier capable of imparting excellent positive charging characteristics such as rising of charging can be obtained.

Continued on the front page (72) Inventor Gen Yamazaki 45 Miyukigaoka, Tsukuba City, Ibaraki Prefecture F-term in Hodogaya Chemical Industry Co., Ltd. (Reference) 2H005 BA02 BA06 BA07 BA11 CA05 CA28 EA05 EA06 EA07

Claims (4)

[Claims] 1. A resin coating layer on a surface of a carrier core material.
A carrier for an electrophotographic developer,
The layer represented by the following general formula (1)
A compound represented by the formula (2) and a compound represented by the following general formula (3)
At least one selected from the group consisting of the compounds represented by
Polymerizes 1 to 100% by weight of various compounds
Electrophotography comprising a polymer obtained by
Carrier for developer. Embedded imageIn the formula, R represents a hydrogen atom or a methyl group;¹ Is the carbon number
1-18 (substituted) alkylene groups, (substituted) phenylene
Group, (substituted) naphthylene group, or (substituted) anthrani
X represents a len group^Two Is a (substituted) alkyl having 1 to 16 carbon atoms
Group, (substituted) phenyl group, (substituted) naphthyl group, or
Represents a (substituted) anthranyl group. Embedded imageWhere R¹ Represents a hydrogen atom or a methyl group;^Two Is carbon
A (substituted) alkylene group of numbers 0 to 2, -COO-, -O
-, -CO-, -NH-CO-, -NR^Three − (R^ThreeIs water
An atom or an alkyl group having 1 to 6 carbon atoms), -OC
O— or a (substituted) phenylene group;¹ Is carbon
A (substituted) alkylene group of the formulas 1 to 16,-(R ^Four O)_n −
(R^Four Represents an alkyl group having 1 to 2 carbon atoms, and n represents 1 to 1
0), (substituted) phenylene group, (substituted) naphthyl
X or a (substituted) anthranylene group;^Two Is
C1-C16 (substituted) alkyl group, (substituted) phenyl
Group, (substituted) naphthyl group, or (substituted) anthrani
Represents a (substituted) phenylene group, (substituted) naph
Represents a tylene group or a (substituted) anthranylene group. Embedded imageIn the formula, R represents a hydrogen atom or a methyl group, and X has 1 carbon atom.
To 18 (substituted) alkyl groups, (substituted) phenyl groups,
A (substituted) naphthyl group or a (substituted) anthranyl group
Represent. 2. A resin coat layer comprising: a compound represented by the general formula (1); a compound represented by the following general formula (2);
2. A polymer obtained by polymerizing a monomer containing 5 to 70% by weight of at least one compound selected from the group consisting of compounds represented by the following general formula (3). A carrier for an electrophotographic developer according to the above. 3. The polymer has a weight average molecular weight of 1,000 to 1,000.
3. The carrier for an electrophotographic developer according to claim 1, wherein the number is 500,000. 4. The carrier core material has a particle diameter of 20 to 300.
4. The carrier for an electrophotographic developer according to claim 1, wherein the carrier has a size of μm.