JPH07140723A - Electrostatic charge image developing carrier and two-component dry color developer using the same - Google Patents

Abstract

PURPOSE:To suppress electric resistance of a coating layer on a carrier and to obtain a carrier having excellent stability of the charge amt. of a developer with time, production stability, color characteristics and durability without decreasing an edge effect and a preventing effect against deposition of a carrier by producing the carrier in such a manner that a conductive material is uniformly present on the surface of the core material but not present in the resin coating film. CONSTITUTION:The carrier is produced in such a manner that the surface of the core material is coated with a resin and a conductive material is uniformly present on the surface of the core material but not present in the resin coating layer. The core particle used is, for example, magnetic metal such as iron and nickel or alloys of these metals and zinc. As for the conductive material, conductive carbon black or other well-known material can be used, and carbon black is preferable considering its large effect to decrease the resistance and depositing property to the core surface. In this constitution, no carbon black is mixed in the resin coating layer so that even when the resin coating layer is scraped, deterioration in color characteristics is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier for an electrostatic latent image developer and a two-component dry color developer, and more particularly to development for developing an electrostatic latent image such as electrophotography and electrostatic recording. The present invention relates to a carrier used as a developer and a two-component dry color developer using the carrier.

[0002]

2. Description of the Related Art So-called two-component dry developers, in which carrier particles are made of a mixture with toner particles, have been well known. In this two-component dry developer, minute toner particles are held on the surface of relatively large carrier particles by the electric force generated by the friction between the particles, and when they are brought close to the electrostatic latent image, the electrostatic latent image is formed. The attraction force in the latent image direction to the toner particles due to the electric field formed by overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and attached onto the electrostatic latent image to visualize the electrostatic latent image. It is a thing. Then, the developer is repeatedly used while replenishing the toner consumed by the development. Therefore, during long-term use, the carrier must always triboelectrically charge the toner particles to the desired polarity and to a sufficient charge amount. However, in the conventional developer, a part of the toner particles physically adheres to the surface of the carrier particles to form a film due to collision between particles, mechanical collision such as collision between particles and developing mechanism, or heat generated by these. There is a property to do. In such a case, a toner film is formed on the surface of the carrier, so-called spent is formed, the charging characteristics of the carrier deteriorate with the use time, and it becomes necessary to replace the entire developer. In order to prevent such spent formation, conventionally, a method of coating various resins on the carrier surface has been proposed, for example, a carrier coated with a resin such as a styrene / methacrylate copolymer, a styrene polymer, Although the charging property is excellent, the critical surface tension of the surface is relatively high, and the spent is formed during repeated copying, so that the life as a developer is not so long. Further, since the carrier coated with the tetrafluoroethylene polymer has a low surface tension, the toner is less likely to be spent, but the tetrafluoroethylene polymer is located on the most negative side in the triboelectric charging series, so that the toner is It cannot be used when negatively charged.

Carriers coated with a coating layer containing a silicone resin have been proposed as those having a low surface tension, such as unsaturated silicone resin and organosilicone,
A carrier surface coated by mixing silanol or the like with styrene / acrylic resin (US Pat. No. 3,562,533)
Carrier) whose surface is coated with a polyphenylene resin and an organosilicon terpolymer resin (US Pat.
847127); a carrier coated with a coating layer containing a silicone resin and a nitrogen-containing resin having a positive charging characteristic (JP-A-55-127567); and a carrier whose surface is coated with a resin-modified silicone resin (special Kaisho 55-1
57571) and the like. As described above, the resin coating improves the spent preventing ability, but since the carrier has a high resistance, there is a drawback that the edge effect is likely to occur and the reproducibility of a wide black region and a halftone region is poor. Further, since the counter charge at the time of toner detachment becomes too large, the carrier is likely to adhere to the non-image area due to electrostatic development. In order to solve this drawback, it has been proposed to mix a conductive substance such as carbon black in the coating layer. For example, one coated with a material containing porous carbon black and a resin as main components (JP-A-56-756).
59) and a silicone resin containing carbon black subjected to coupling treatment (JP-A-62-
No. 182759) and the like.

When the surface of the carrier is coated with a resin containing carbon black as described above, the resistance of the carrier can be easily adjusted and the edge effect and the carrier adhesion can be improved. There is a problem that carrier adhesion occurs. Further, if too much carbon black is added to reduce the resistance of the carrier, the coat film becomes weak and film abrasion occurs, and the resistance of the carrier fluctuates due to repeated use of the developer, and a stable image cannot be obtained. Occur. Further, when it is used as a carrier for a two-component dry developer, the resistance of the toner becomes high, and therefore the resistance must be lower than that of the black developing carrier. Therefore, the amount of carbon black added to the resin coating layer is increased or an uncoated core material is used, but when an uncoated carrier is used, the charging ability is lowered due to the occurrence of spent, and a long-life developer is obtained. However, if a carrier having a low resistance by increasing the amount of carbon black is used, the coating layer is scraped and the grayness, which is one of the color characteristics, deteriorates, which is not preferable in practical use. Therefore, in order to obtain a long-life carrier while maintaining color characteristics, a carrier has been proposed in which a conductive material is embedded in advance in a concave portion of an irregular-shaped carrier core material and then coated with a resin (Japanese Patent Laid-Open No. 1-13).
No. 3067). However, this method can be used not only for those having irregularities on the surface of the core material, but also for the problem that the conductive material cannot be uniformly reduced in resistance because the conductive material is unevenly distributed only in the depressions. Have

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and suppresses the electric resistance of the coating layer of the carrier to a low level, without damaging the edge effect and the strong prevention effect against carrier adhesion. An object of the present invention is to provide a carrier for a developer, which has excellent stability over time in the amount of charge of the developer and manufacturing stability, and also has excellent color characteristics and durability, and a developer using the carrier.

[0006]

The present invention provides (1) a carrier for a two-component electrostatic latent image developer comprising a core material surface coated with a resin, in which a conductive material is uniformly present on the core material surface. A carrier for an electrostatic latent image developer, characterized in that no conductive material is present in the coating. (2) A carrier for an electrostatic latent image developer, wherein the conductive material is carbon black. (3) A carrier for an electrostatic latent image developer, wherein the resin of the resin coating layer is a silicone resin or a fluororesin. (4) A carrier for an electrostatic latent image developer, wherein the resin coating layer has a thickness of 0.5 to 3 μm. (5) A combination of the above-mentioned carrier for electrostatic latent image developer of 1, 2, 3 or 4 and a color toner.
The main point is component type dry color developers. The present invention will be described in more detail below.

The core material particles used in the present invention include, for example, magnetic metals such as iron, nickel and cobalt, alloys of these metals with metals such as zinc, tin, lead and manganese, and various ferrites and magnetites. The particle size of the particles is preferably 20 to 200 μm,
The shape of the particles may be an irregular shape represented by reduced iron powder or a spherical shape such as ferrite or magnetite. As the conductive material, conductive carbon black or other known materials can be used, and carbon black is preferable from the viewpoint of having a large effect of lowering resistance and adhering to the surface of the core material. Generally, in a color developer, when carbon black is added, the coating layer is scraped off, and at the same time, the carbon black is scraped off to deteriorate the grayness which is one of the color characteristics. However, according to the present invention, carbon black is not mixed in the resin for the coating layer, and the color characteristics are not deteriorated even if the resin layer is scraped. With respect to the particle size of the conductive material, since the air is not used for forming the fluidized bed at the time of coating, the conductive material adhered to the surface of the core material can be stably manufactured without scattering. Specific examples of the conductive material include Black Pearls 2000, VULCAN.
XC-7 (made by Cabot), Ketjen Black
EC-DJ600 (Ryan Akzo), Denka B
rack granular, powdery (made by Denki Kagaku Kogyo Co., Ltd.), COND
UCTEX 975, CONDUCTEX SC (Columbia Carbon), # 40, 44, 45 (Mitsubishi Kasei), Printex L, Printex L-6,
Printex 60 (manufactured by Degussa) and the like are mentioned, and the particle size of this conductive material is preferably 0.1 to 0.3 μm.

As the silicone resin used in the present invention, a known silicone resin can be used, and examples thereof include straight silicone consisting only of organosiloxane bonds and silicone resin modified with alkyd polyester, epoxy, urethane and the like. Specific examples include those represented by the following general formula.

[0009]

[Chemical 1] In the formula, R ₁ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, R ₂ and R ₃ are hydroxyl groups, and a carbon number is 1
To alkyl group having 4 to 4 carbon atoms, alkoxyl group having 1 to 4 carbon atoms, phenyl group, phenoxy group, alkenyloxy group having 2 to 4 carbon atoms, hydroxyl group, carboxyl group, ethylene oxide group, glycidyl group or group represented by the following formula

R ₄ and R ₅ are a hydroxyl group, a carboxyl group, an alkoxy group having 1 to 4 carbon atoms, and 2 to 4 carbon atoms.
Alkenyl group, an alkenyloxy group having 2 to 4 carbon atoms,
Phenyl group, phenoxy group, k, l, m, n, o and p are integers of 1 or more.

Each of the above substituents has a substituent such as an amino group, a hydroxyl group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, a glycidyl group, and a halogen atom, in addition to an unsubstituted group. May be.

Specific examples of these are K manufactured by Shin-Etsu Chemical Co., Ltd.
R271, KR255, KR251, straight silicone resin such as SR2400, SR2406 manufactured by Straight Silicone, KR206 (alkyd modified), KR3093 (acrylic modified), ES1001 manufactured by Shin-Etsu Chemical Co., Ltd.
N (epoxy modified), SR manufactured by Toray Dow Corning
Examples of the modified silicone resin include 2115 (epoxy modified) and SR2110 (alkyd modified). Specific examples of the fluororesin include polytetrafluoroethylene (PT
FE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoroethylene copolymer (FEP), polychlorotrifluoroethylene (PC
TFE) and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).
The thickness of the resin coating layer using these resins is preferably 0.5 μm or more because it is necessary that the conductive material is completely coated with the resin, and when it is too thick, the effect of lowering the resistance is obtained. Since it is less, 3.0 μm or less is preferable. In the carrier of the present invention, the core material and the conductive material are stirred, and the conductive material is physically and electrically attached to the surface of the core material. Next, a resin solution can be prepared by coating the surface of the core material particles in a fluid state with a resin. The carrier of the present invention makes it possible to reduce the resistance of the coated carrier without containing carbon black in the resin layer, and since there is no carbon black on the carrier surface, the charge amount of the developer decreases with time and during production. Less susceptible to the environment. Further, since a coating film having a uniform composition (where the conductive material does not appear on the surface of the carrier) is formed, it is equivalent to the resin-coated carrier without an additive even in the spent process.

Known toners can be used as the toner constituting the developer together with the carrier of the present invention. These toners are well mixed with a resin component and a coloring agent such as carbon black usually necessary for forming a visible image, After kneading with a hot roll mill,
It is obtained by cooling, solidifying, pulverizing and classifying. The carrier and toner are preferably used in such an amount that the toner particles adhere to the surface of the silicone resin of the carrier particles and occupy 30 to 90% of the surface area of both particles. In particular, the carrier of the present invention is highly useful as a two-component dry color developer. That is, since carbon black cannot be used for the color developer, the toner resistance increases, and the carrier resistance must be further reduced as compared with the black carrier in order to reduce the resistance of the developer. At that time, it is common to put a conductive material in the resin coating layer, but with the abrasion of the resin coating layer, the conductive material is also abraded, which causes a problem that the color characteristics of the toner are deteriorated. The carrier does not contain a conductive material in the coating resin, and the color characteristics are not deteriorated at all.

[0014]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited thereto.
All "parts" in the examples mean parts by weight.

Example 1 Preparation of carrier Silicone resin liquid 300 parts (Toray Dow Corning Silicone resin SR2406) Toluene 300 parts Carbon black (Degussa Printex L-6) 10 parts Ferrite (Powdertec FL-100) ) 5000 parts Carbon black and ferrite having an average particle size of 0.1 to 0.3 μm are charged into a rotary vane type mixing container heated to 100 ° C. and stirred at 120 rpm for 5 minutes. Next, a mixed solution of a silicone resin solution and toluene was sprayed with a two-fluid nozzle and then dried to form a film having a thickness of 1.0 μm. Next, the silicon film was cured by heating at 200 ° C. for 2 hours to prepare the carrier of the present invention. Preparation of Toner Styrene and n-butyl methacrylate copolymer 80 parts Carbon black 10 parts 2: 1 type chromium complex salt dye of monoazo dye 3 parts A toner having an average particle diameter of 11 μm having the above composition was prepared. The developer of the present invention was prepared by mixing 3.5 parts of the toner with 100 parts of the carrier.

Comparative Example 1 Preparation of Carrier Silicone Resin Liquid 300 parts (Toray Dow Corning Silicone Resin SR2406) Toluene 1000 parts Carbon Black (Degussa Printex L-6) 20 parts Ferrite (Powdertec FL-100) ) 5000 parts A silicone resin solution, toluene and carbon black were dispersed for 20 minutes with a homomixer to prepare a liquid. Next, ferrite was put into a rotary fluidized bed coating device and mixed while flowing. Next, it was heated at 200 ° C. for 2 hours to cure the silicon film to prepare a carrier for comparison. Preparation of Toner The same toner as in Example 1 was used as the toner, and the carrier 10
A developer for comparison was prepared by mixing 3.5 parts of toner with 0 part.

Example 2 Preparation of Toner Polyester resin (382A manufactured by Kao Corporation) 100 parts Yellow colorant 5 parts (Shimura First Yellow GF manufactured by Dainippon Ink and Chemicals, Inc.) A toner having an average particle diameter of 12 μm was prepared. The developer of the present invention was prepared by mixing 3.0 parts of the toner with 100 parts of the carrier.

Comparative Example 2 A comparative developer was prepared in the same manner as in Example 2 except that the same carrier as in Comparative Example 1 was used.

Example 3 Preparation of Carrier Polytetrafluoroethylene (solid content 60%) 300 parts (manufactured by Daikin Industries, Ltd.) Carbon black (Printex L manufactured by Degussa) 10 parts Fluorine surfactant 1% aqueous solution 1500 parts (Sumitomo 3M FC-134 manufactured by the company) Ferrite (FL-100 manufactured by Powder Tech Co., Ltd.) 5000 parts Carbon black and ferrite prepared to have an average particle size of 0.1 to 0.3 μm are charged into a rotary blade type mixer, and the temperature is 100 ° C.
The mixture was stirred at 120 rpm for 5 minutes under the atmosphere. Next, a mixed solution of a silicone resin solution and toluene was sprayed with a two-fluid nozzle and then dried to form a film having a thickness of 1.0 μm. Next, the fluororesin film was cured by heating at 370 ° C. for 2 hours to prepare the carrier of the present invention. Preparation of Toner Styrene resin (D-125 manufactured by Esso) 100 parts Yellow colorant 5 parts (Shimura First Yellow GF manufactured by Dainippon Ink and Chemicals, Inc.) A toner having an average particle diameter of 11 μm having the above composition was prepared. The developer of the present invention was prepared by mixing 3.5 parts of the toner with 100 parts of the carrier.

Comparative Example 3 Preparation of Carrier Polytetrafluoroethylene (solid content 60%) 300 parts (manufactured by Daikin Industries, Ltd.) Carbon black (Printex L, manufactured by Degussa) 20 parts Fluorine surfactant 1% aqueous solution 1500 parts (Sumitomo 3M FC-134 manufactured by the company) Ferrite (FL-100 manufactured by Powder Tech Co., Ltd.) 5000 parts A resin solution, a surfactant and carbon black were placed in a homomixer and dispersed for 20 minutes to prepare a liquid. Next, ferrite was put into a rotary fluidized bed coating device, and the prepared liquid was sprayed while flowing, and then dried. Then 370
The fluororesin film was cured by heating at 0 ° C. for 2 hours to prepare a carrier for comparison. Preparation of Toner The same toner as in Example 3 was used, and the carrier 1 was used.
To 100 parts of the toner, 3.5 parts of the toner was mixed to prepare a comparative developer.

Comparative Example 4 A comparative developer was prepared in the same manner as in Example 1 except that 100 parts of the silicone resin and toluene of Example 1 were used to obtain a film thickness of 0.3 μm.

Example 4 A developer of the present invention was prepared in the same manner as in Example 1 except that the silicone resin of Example 1 and toluene were 100 parts to make the film thickness 3.0 μm.

Comparative Example 5 A comparative developer was prepared in the same manner as in Example 1 except that 1200 parts of the silicone resin and toluene of Example 1 were used to make the film thickness 4.0 μm.

In the developers of Examples 1 to 3 and Comparative Examples 1 to 3, 50 g of the carrier was put in a 100 ml ball mill stirrer, 1.5 g of the toner was put, and 300 r
After stirring at pm for 10 minutes, the developer was taken out and its charge amount was measured. The results are shown in Table 1.

[0025]

[Table 1] Rate of decrease in charge amount (%) = (A−B) / A × 100 A: Charge amount immediately after production B: Charge amount after 7 days The resistance was represented by a value obtained by logarithmically converting the volume specific resistance (Ωcm). Environmental fluctuation rate (%) = (C−D) / D × 100 C: physical properties of carrier coated at 30 ° C., 80% D: physical properties of carrier coated at 30 ° C., 30 ° C. It can be seen that the developer is excellent in terms of charge amount and environmental fluctuation rate.

Next, a solid image was formed with the developers of Examples 2 and 3 and Comparative Examples 2 and 3, and the I.D. D. (Image Density) was measured by Macbeth reflection densitometer (RD-514) and Kodak Ratten filter # 25 (R), # 47 (B), # 5.
8 (G), the maximum concentration is H, the intermediate concentration is M,
The color characteristics were evaluated as the lowest density L. The results are shown in Table 2.

[0027]

[Table 2] E (efficiency) (%) = {1- (ML) / 2H} ×
100 G (grayness) (%) = L / H × 100 H (hue error) (%) = (ML) / (HL) × 1
00 When the grayness is high, color stains are conspicuous, and especially when it is a stain of a different color, it appears remarkably, and in particular, a difference is clearly seen because it is a color mixture of carbon black with yellow toner.
From the above results, it can be seen that the developer of the present invention is excellent.

Next, with respect to Examples 1, 4, 5 and Comparative Example 4, the state of adhesion of the carrier was visually observed at the start and after 1000 sheets were continuously copied by a copying machine FT5840 manufactured by Ricoh. The results are shown in Table 3.

[0029]

[Table 3] From the above result, the layer thickness of the resin coating layer is 0.5 to 3.0 μm.
It turns out that is preferable.

[0030]

[Effect] According to the present invention, the electric resistance of the coating layer of the carrier is kept low, the edge effect and the strong prevention effect against carrier adhesion are not impaired, and the stability of the charge amount of the developer and the production stability are excellent, and further excellent. A developer carrier having excellent color characteristics and durability and a developer using the same are obtained.

Claims (5)

[Claims] 1. A carrier for an electrostatic latent image developer comprising a core material surface coated with a resin, wherein a conductive material is uniformly present on the core material surface, and a conductive material is present in the resin coating layer. A carrier for an electrostatic latent image developer characterized by not doing. 2. The carrier for electrostatic latent image developer according to claim 1, wherein the conductive material is carbon black. 3. The resin of the resin coating layer is a silicone resin or
The carrier for an electrostatic latent image developer according to claim 1, which is a fluororesin. 4. The carrier for electrostatic latent image developer according to claim 1, wherein the resin coating layer has a thickness of 0.5 to 3 μm. 5. A two-component dry color developer comprising the carrier for electrostatic latent image developer according to any one of claims 1, 2, 3 and 4 and a color toner in combination.