JP2000227680A - Electrostatic latent image developing carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carrier having good electrostatic charge controllability, giving a sufficient quantity of electric charges to a toner, less liable to cause toner spending on the carrier even after long-time use and less liable to reduce the quantity of electric charges or to lower its electrostatic charging ability by incorporating an organosilicon compound having a specified quaternary ammonium salt structure into a coating layer. SOLUTION: The carrier for a dry two-component developer has a resin coating layer on the surface of a core material and contains an organosilicon compound having a quaternary ammonium salt structure of the formula in the coating layer. In the formula, R1-R3 are each 1-6C alkyl, phenyl or substituted phenyl, R4 is alkyl, substituted alkyl, alicyclic alky, phenyl, substituted phenyl, benzyl or substituted benzyl, X is halogen, the residue of benzenesulfonic acid, the residue of substituted benzenesulfonic acid, the residue of hydroxynaphthalenesulfonic acid, BPh4, BF4, ClO4 or SbCl5 and (n) is 1 or 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry two-component developer carrier used for electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art In a dry developing method used in electrophotography, a visible image is formed by electrostatically adhering a powder toner rubbed with a frictional charging member to an electrostatic latent image. is there. In this dry development method, a so-called one-component development method using only toner as a main component, and a mixture of toner and glass beads, a magnetic carrier, or a coated carrier whose surface is coated with a resin or the like are used. There is a so-called two-component system.

In the latter two-component developer, fine toner particles are held on the surface of relatively large carrier particles by electric force generated by friction between the two particles. When approaching the electrostatic latent image, the electric field generated by the electrostatic latent image causes the toner particles to overcome the bonding force with the carrier particles and to be developed on the electrostatic latent image. The developer is used repeatedly while replenishing the toner consumed by the development. Therefore, the carrier particles can be used for a long time,
The toner particles must always be frictionally charged to a desired polarity and to a sufficient charge amount.

However, the toner is fused to the surface of the carrier particles due to the collision between the particles, the mechanical agitation in the developing device, or the heat generated by these, and so-called spent toner is generated. Declines over time. As a result, background smearing of the image and toner scattering occur, so that it is necessary to replace the entire developer.

In order to prevent such spent, the life of the carrier has been extended by coating the surface of the carrier core material with a resin having a low surface energy, for example, a fluororesin or a silicone resin. Examples of the carrier coated with a resin having a low surface energy include the following.

JP-A-55-127569: Carrier coated with a room-temperature-curable silicone resin and a positively-chargeable nitrogen resin JP-A-55-157751: Coated with a coating material containing at least one modified silicone resin Carrier JP-A-56-140358: Carrier having a resin coating layer containing a room temperature-curable silicone resin and styrene-acrylic resin JP-A-58-207054: The surface is coated with a silicone resin containing silicon carbide Carrier JP-A-61-110161: 20 dyn / cm
Positively chargeable carrier coated with a material having the following critical surface tension: JP-A-62-273576: a carrier coated with a coating material containing a fluoroalkyl acrylate,
Developer composed of toner containing chromium-containing azo dye

However, in recent years, low-temperature fixable toners have been demanded for energy saving, and in order to obtain a sufficient color tone, toners having a low softening point are used. Often done.
Further, the toner tends to be reduced in particle size for higher image quality. When a developer using such a toner is used for a long time, spent toner is apt to be generated on the carrier, and the charge amount of the toner is reduced, the toner is scattered, and the background is stained. It is.

[0008]

Accordingly, it is an object of the present invention to provide a carrier having the following characteristics. 1) A carrier having good charge controllability and capable of obtaining a sufficient amount of toner charge; 2) A carrier having a small amount of toner spent on the carrier even after long-term use and a small decrease in charge amount ability; 3) Toner scattering and background A carrier that can maintain high image quality for a long time without causing dirt.

[0009]

Means for Solving the Problems The present inventors have intensively studied means for achieving the above object, and as a result, a silicone resin having a specific compound contained in a coating material and further having a specific film structure. The present inventors have found that the above object can be achieved by combination with the system, and have reached the present invention. That is, according to the present invention, first, in a dry two-component developer carrier having a resin coating layer on the surface of a core material, a quaternary ammonium salt structure represented by the following general formula (I) is contained in the coating layer. The present invention provides a carrier for developing an electrostatic latent image, characterized by containing an organosilicon compound.

Embedded image (Wherein, R ₁ , R ₂ , and R ₃ represent an alkyl group having 1 to 6 carbon atoms or a phenyl group or a substituted phenyl group, and R ₄ represents an alkyl group, a substituted alkyl group, an alicyclic alkyl group, a phenyl group,
Represents a substituted phenyl group, a benzyl group or a substituted benzyl group. Further, X represents a halogen atom, sulfonic acid residue, a substituted benzenesulfonic acid residue, hydroxy naphthalenesulfonic acid residues, or BPh _4, BF _4, a ClO ₄ or SbCl _5. n is a positive integer and represents 1 or 2. Secondly, the carrier for developing an electrostatic latent image according to the first aspect is provided, wherein X of the compound (I) contained in the coating layer is a paratoluenesulfonic acid residue. .
Thirdly, there is provided the carrier for developing an electrostatic latent image according to the first aspect, wherein the compound (I) contained in the coating layer is a bisammonium compound. Fourth,
The electrostatic latent image developing carrier according to the first aspect, wherein the resin coating layer is made of a silicone resin. Fifthly, there is provided the carrier for developing an electrostatic latent image as described in the fourth aspect, wherein the content of the compound (I) is larger as the material is closer to the core material in the thickness direction of the coating material. Sixthly, there is provided the carrier for developing an electrostatic latent image according to the fourth feature, wherein the lower the resistance material is, the closer to the surface layer in the thickness direction of the coating material. Seventh, in the thickness direction of the coating material, the amount of the compound (I) is larger as the material is closer to the core material, and the lower resistance material is contained more as the material is closer to the surface layer. The described carrier for electrostatic latent development is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The electrostatic latent image developing carrier of the present invention,
A carrier having a resin coating layer on the surface of a core material, characterized in that the coating layer contains a compound of an organosilicon having a quaternary ammonium salt structure represented by the general formula (I).

The organosilicon compound having a quaternary ammonium salt structure represented by the general formula (I) is obtained by converting 3-N, N-dimethylaminopropylsilane represented by the following general formula (A) to the following general formula: The quaternizing agent represented by (B) is 4
It is obtained by grading.

Embedded image (Wherein R ₁ , R ₂ and R ₃ are a C ₁ to C ₆ alkyl group,
Represents a phenyl group or a substituted phenyl group. R ₄ X (B) wherein R ₄ is an alkyl group, a substituted alkyl group, an alicyclic alkyl group, a phenyl group, a substituted phenyl group, a benzyl group,
Represents a substituted benzyl group. X represents a halogen atom, a benzenesulfonic acid residue, a substituted benzenesulfonic acid residue,
Hydroxynaphthalenesulfonic acid residue, BPh ₄ , B
Represents F ₄ , ClO ₄ or SbCl ₅ . )

The organosilicon compound having a quaternary ammonium salt structure represented by the general formula (I) of the present invention is used by being contained in a resin coating layer. As coating resin,
Polymers composed of various monomers can be used. Among the compounds represented by the general formula (I), bisammonium compounds and compounds in which X in the formula is a paratoluenesulfonic acid residue are particularly preferred.

Examples of the organosilicon compound having a quaternary ammonium salt structure represented by the general formula (I) include those shown in Table 1.

[0014]

[Table 1]

In the carrier of the present invention, the resin coating layer is preferably made of a silicone resin. Examples of the silicone resin that can be used as the coating resin in the present invention include a silicone resin containing a repeating unit represented by the following general formula.

Embedded image In the above formula, R represents a hydrogen atom, a halogen atom, a hydroxy group, a methoxy group, a C ₁ -C ₄ lower alkyl group or a phenyl group.

Such silicone resins include, as straight silicone resins, KR271, KR272,
KR282, KR252, KR255, KR152 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406 (manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like. Examples of the modified silicone include an epoxy-modified silicone, an acrylic-modified silicone, a phenol-modified silicone, a urethane-modified silicone, a polyester-modified silyone, and an alkyd-modified silicone. Examples of the modified silicone include epoxy-modified: ES-1001N,
Acrylic-modified silicone: KR-5208, polyester-modified: KR-5203, alkyd-modified: KR-20
6, urethane-modified: KR-305 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), epoxy-modified: SR2115, alkyd-modified: SR2110 (manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like.

In the carrier of the present invention, it is preferable that the closer to the core in the thickness direction of the coating material, the higher the content of the compound represented by the formula (I). This is because it is possible to prevent a decrease in the chargeability of the carrier due to spent by utilizing the scraping of the resin film and the charge controllability of the organosilicon compound having a quaternary ammonium salt structure. That is, in detail, with the repeated use of the carrier, the coating of the silicone resin is gradually abraded, so that the closer to the core material in the thickness direction of the coating material, the higher the content of the compound represented by the general formula (I). If you increase the amount,
Along with the shaving, a carrier coat layer having a high triboelectric charging ability appears to prevent a decrease in the charge amount over time. In order to increase the ratio of the compound represented by the general formula (I) closer to the carrier core material, two kinds of coating solutions having different contents of the compound are prepared, and one of the coating solutions is applied. The other coating solution may be supplied at an arbitrary ratio. This allows
A long-life carrier having good charge stability can be obtained.

In the present invention, it is preferable that the closer to the surface layer in the thickness direction of the coating material, the more the low resistance material is contained. This is because, in a silicone resin-coated carrier containing an organosilicon compound, the lower the resistance of the coating material in the surface layer of the coating material, the lower the decrease in carrier charging ability due to coating shaving over time. This is because This is considered to be the result of the fact that the amount of the low-resistance substance in the coating material limits the saturation charging ability of the carrier, and the higher the content of the low-resistance substance, the lower the charging ability of the carrier. In order to increase the ratio of the low-resistance substance closer to the surface layer of the carrier coating material, two coating liquids having different low-resistance substance contents are prepared, and one coating liquid is applied while the other coating liquid is applied. May be input at an arbitrary ratio. As a result, a long-life carrier having good charge stability can be obtained.

There are the following resistance adjusters that can be used. Metal powders such as conductive ZnO and Al, SnO ₂ produced by various methods, and Sn doped with various elements
O ₂ borides, e.g. _{TiB 2, ZnB 2, MoB 2} , silicon carbide, and the conductive polymer (polyacetylene, polyparaphenylene, poly (para - phenylene sulfide), polypyrrole, polyethylene - carbon black), and the like.

Further, in the present invention, in the thickness direction of the coating material, the closer to the core material, the larger the amount of the compound represented by the general formula (I), and the closer to the surface layer, the more the low-resistance substance is contained. In this case, the decrease in the charge amount over time becomes smaller, and high image quality is maintained.

In the present invention, the following resins can be used alone or as a mixture of two or more of them. That is, for example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer,
Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-
Maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer Styrene-phenyl acrylate copolymer), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer,
Styrene-phenyl methacrylate copolymer), styrene-α-methyl methyl acrylate copolymer, styrene-
Styrene resin such as acrylonitrile-acrylate copolymer, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyamide resin, phenol Resins, silicone resins, polycarbonate resins, melamine resins, and the like.

[0022]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, all parts shown are on a weight basis.

Production Example 1 (Preparation of Toner A) Polyester (weight average molecular weight 12000) 100 parts Copper phthalocyanine pigment 2 parts Polarity control agent 2 parts

Embedded image The above-mentioned material was kneaded with a hot roll at 120 ° C., solidified by cooling, pulverized and classified to obtain a full-color cyan toner having a volume average particle size of 7.1 μm. Further, the toner 10
For 0 parts, silica R972 (manufactured by Nippon Aerosil Co., Ltd.)
Was added and mixed to obtain a toner A.

Production Example 2 (Preparation of Carrier B) A liquid was prepared by dissolving 5 parts of a methyl methacrylate resin (molecular weight: about 300,000) in 95 parts of toluene. Next, a liquid was applied to the carrier core material (CuZn ferrite, particle diameter 50 μm, saturation magnetic moment 55 emu / g) using a fluidized bed type coating apparatus, and the average film thickness was 0.17.
A μm resin-coated carrier B was obtained.

Example 1 (Preparation of Carrier C) A liquid was prepared by dissolving 10 parts of an organosilicon compound having a quaternary ammonium salt structure represented by the following formula (3) in 90 parts of butyl cellosolve. Ph ₃ SiCH ₂ CH ₂ CH ₂ N ⁺ Me ₂ (nBu) I ⁻ (3) 100 parts of the liquid prepared in Production Example 2 was added to liquid 10
Of the carrier core material (CuZn ferrite, particle diameter 50 μm, saturation magnetic moment 55 emu /
g) was applied using a fluidized bed type coating apparatus to obtain a resin-coated carrier C having an average film thickness of 0.19 μm.

Example 2 (Preparation of Carrier D) Example 1 was repeated except that an organosilicon compound (4) represented by the following formula was used instead of the organosilicon compound (3) having a quaternary ammonium salt structure. A carrier was prepared in exactly the same manner as described above to obtain D-coated carrier having an average film thickness of 0.18 μm.

Embedded image

Example 3 (Preparation of Carrier E) Example 1 was repeated except that an organosilicon compound (10) represented by the following formula was used in place of the organosilicon compound (3) having a quaternary ammonium salt structure. A carrier was prepared in exactly the same manner as described above to obtain a loquat-coated carrier E having an average film thickness of 0.19 μm.

Embedded image

Example 4 (Preparation of Carrier F) 10 parts of an organosilicon compound having a quaternary ammonium salt structure represented by the following formula (3) was dissolved in 90 parts of butyl cellosolve to prepare a liquid. _{Ph 3 SiCH 2 CH 2 CH 2} N + Me 2 (nBu) I - (3) Next, the following formulation was adjusted liquid. Silicone resin U (weight average molecular weight about 4000): 100 parts toluene solution with 10% solid content

Embedded image 0.5 part of catalyst (CH ₃ ) ₂ Sn (OCOCH ₃ ) ₂ 20 parts of liquid are mixed with 100 parts of liquid, and this liquid is mixed with a carrier core material (CuZn ferrite, particle size 50 μm,
The coating was performed under a 100 ° C. atmosphere using a fluidized bed type coating apparatus with respect to a saturated magnetic moment of 55 emu / g). Further, the resin-coated particles were heated at 150 ° C. for 1 hour to obtain a silicone resin-coated carrier F. The average film thickness was 0.18 μm.

Example 5 (Preparation of Carrier G) A coating solution was prepared in exactly the same manner as in Example 4, except that the organosilicon compound (3) having a quaternary ammonium salt structure was changed to 20 parts. To 100 parts of the coating solution, 100 parts of the coating solution was added at a rate of 5 parts / minute while being uniformly dispersed, and at the same time, the solution was mixed with a carrier core material (CuZn ferrite, particle size 50 μm, saturation magnetic moment 55 emu / g) was applied over a period of 20 minutes in a 100 ° C. atmosphere using a fluidized bed type coating apparatus. Further, the resin-coated particles were heated at 150 ° C. for 1 hour to obtain a silicone resin-coated carrier G. The average film thickness was 0.19 μm.

Example 6 (Preparation of Carrier H) 100 parts of the liquid prepared in Example 4 was applied to carbon (Lion Akzoketjen Black EC-DJ60).
0) Add 10 parts, disperse with a homomixer for 30 minutes,
A coating solution was obtained. Next, 100 parts of the coating solution was added to 100 parts of the coating solution while being uniformly dispersed at a rate of 5 parts / minute, and at the same time, the solution was mixed with a carrier core material (CuZn ferrite, particle diameter 50 μm, With respect to a moment of 55 emu / g), coating was performed using a fluidized bed type coating apparatus under an atmosphere of 100 ° C. for 20 minutes. Further, the resin-coated particles were heated at 150 ° C. for 1 hour to obtain a silicone resin-coated carrier H. The average film thickness was 0.19 μm.

Example 7 (Preparation of Carrier I) While 100 parts of the coating liquid prepared in Example 5 was uniformly dispersed at a rate of 5 parts / minute with respect to 100 parts of the coating liquid prepared in Example 6. At the same time, the solution was added to a carrier core material (CuZn ferrite, particle size 50 μm, saturation magnetic moment 55 emu / g) at 100 ° C. using a fluidized bed type coating apparatus.
It was applied over 0 minutes. Further, the resin-coated particles are
Heat at 0 ° C for 1 hour to prepare silicone resin-coated carrier I
I got The average film thickness was 0.20 μm.

Application Example 1 Toner A (6 parts) was added to carrier C (100 parts) and stirred by a ball mill for 10 minutes to prepare a developer. The toner charge amount was -14.8 μc / g. Met. Next, Pretail 500 (Ricoh full-color copier)
When the image was displayed in the single-color mode using, high image quality without background contamination was obtained. Subsequently, when a continuous copy test of 20,000 sheets was performed, toner scattering was slightly observed from about 15,000 sheets. However, even after 20,000 sheets, high image quality without background stain was maintained. The toner charge amount after the 20,000-sheet copy test was -10.7 μc / g.

COMPARATIVE EXAMPLE 1 Toner A (6 parts) was added to carrier B (100 parts) and stirred by a ball mill for 10 minutes to prepare a developer. The toner charge amount was -9.8 μC / g. Met. Next, Pretail 500 (Ricoh full-color copier)
When the image was displayed in the single-color mode using, high image quality without background contamination was obtained. After a continuous copy test of 20,000 sheets, toner scattering began to occur immediately.
At the time of 10,000 sheets, both the toner scattering and the background stain became very bad. The toner charge amount after the 20,000-sheet copy test was -4.
It was as low as 7 μc / g.

Hereinafter, tests of Carrier D to Carrier I were carried out in exactly the same manner as in Application Example 1. Table 2 shows the results of Application Examples 2 to 7.

[0035]

[Table 2]

Preferred embodiments of the carrier of the present invention include the following embodiments. (1) a coating layer comprising a methyl methacrylate resin containing an organic silicon compound having a quaternary ammonium salt structure; and (2) a coating layer comprising a quaternary ammonium salt structure organic silicon compound / p-toluenesulfonic acid residue. A carrier comprising methyl methacrylate resin, (3)
(4) a carrier whose coating layer is made of a methyl methacrylate resin containing a bisammonium / organic silicon compound;
(5) a carrier comprising a silicone resin whose coating layer contains an organic silicon compound having a quaternary ammonium salt structure;
A carrier containing a larger amount of an organic silicon compound having a quaternary ammonium salt structure as the coating layer is closer to the core material in the thickness direction; (6) a coating layer containing the organic silicon compound having a quaternary ammonium salt structure, (7) The more the coating layer is closer to the core material, the more the quaternary ammonium salt structure organic silicon compound is contained, and the closer to the surface, the more the low resistance substance is contained. Carrier to do.

[0037]

According to the present invention, a specific organic silicon compound having a quaternary ammonium salt structure is contained in a resin coating layer of a carrier. The above organic silicon compound is contained in a silicone resin. In the depth direction, by providing a concentration gradient of the organic silicon compound and the conductive material, it is possible to provide a carrier that imparts sufficient charge to the toner, and has a small decrease in the charge amount over time,
Even when used for a long time, toner scattering and background contamination do not occur, and high image quality is maintained.

Claims (7)

[Claims] 1. A dry two-component developer carrier having a resin coating layer on a core material surface, wherein the coating layer contains an organosilicon compound having a quaternary ammonium salt structure represented by the following general formula (I). A carrier for developing an electrostatic latent image. Embedded image (Wherein R ₁ , R ₂ and R ₃ represent an alkyl group having 1 to 6 carbon atoms, a phenyl group or a substituted phenyl group, and R ₄ represents an alkyl group, a substituted alkyl group, an alicyclic alkyl group, a phenyl group,
Represents a substituted phenyl group, a benzyl group or a substituted benzyl group. Further, X represents a halogen atom, sulfonic acid residue, a substituted benzenesulfonic acid residue, hydroxy naphthalenesulfonic acid residues, or BPh _4, BF _4, a ClO ₄ or SbCl _5. n is a positive integer and represents 1 or 2. ) 2. X of the compound (I) contained in the coating layer
2. The carrier for developing an electrostatic latent image according to claim 1, wherein is a p-toluenesulfonic acid residue. 3. The compound (I) contained in the coating layer,
2. The electrostatic latent image developing carrier according to claim 1, wherein the carrier is a bisammonium compound. 4. The electrostatic latent image developing carrier according to claim 1, wherein the resin coating layer is made of a silicone resin. 5. The carrier for developing an electrostatic latent image according to claim 4, wherein in the thickness direction of the coating material, the content of the compound (I) increases as the distance from the core material increases. 6. The carrier for developing an electrostatic latent image according to claim 4, wherein the lower the resistance material is, the closer to the surface layer in the thickness direction of the coating material. 7. The method according to claim 4, wherein in the thickness direction of the coating material, the amount of the compound (I) is larger as the material is closer to the core material, and the lower resistance material is more contained as the material is closer to the surface layer. The carrier for developing an electrostatic latent image according to the above.