JPH0777823A - Dry two-component developer - Google Patents

Abstract

PURPOSE:To obtain a dry two-component developer having satisfactory developing ability, fluidity and transferability by regulating the shape factor of a replenished toner to a specified range and making the shape factor of a toner in an initial developer higher than that of the replenished toner by a specified range. CONSTITUTION:In a dry two-component developer consisting of a carrier and a toner, the shape factor of the toner in the initial developer is made higher than the shape factor (55-85%) of a replenished toner by 5-10%. The shape factor of the toner is represented by [(the specific surface area of spheres having the same volume as the toner particles)/(the specific surface area of the toner particles)] X 100%. The higher shape factor is attained by mixing the toner with the carrier at a temp. within the range from Tg-30 deg.C to Tg+10 deg.C (Tg is the glass transition temp. of the bonding resin of the toner). Since the shape (sphericity) of the toner in the initial developer is regulated from the early stage, the objective dry two-component developer having satisfactory developing ability, flowability and transferability is obtd.

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 comprising a carrier and a toner, which is used in an image forming apparatus to which the so-called Carlson process is applied, such as an electrostatic copying machine and a laser beam printer.

[0002]

2. Description of the Related Art In electrophotography or electrostatic recording, an electrostatic latent image formed on a photoconductor or electrostatic recording material is visualized with a developer, and the toner image is transferred onto a transfer paper and then fixed. Then, a copy is obtained. In such a method, a dry two-component developer composed of a carrier and a toner is generally used as the developer. With a dry two-component developer, friction is generated between the carrier and the toner by stirring in the developing device, and the toner is given a charge of the opposite polarity to the electrostatic latent image to adhere to the latent image for development. Be seen. The developer used first in the developing device is a mixture of toner and carrier in a predetermined ratio and is called a start developer or an initial developer. In recent years, the toners and carriers that make up this initial developer are required to have higher image quality and higher functionality. In particular, the toner has a smaller particle size, and in addition, the charging and charging that show most of the performance of the developer are performed. In order to improve the image quality centered on the amount, it has been attempted to reexamine the stirring and mixing conditions of these toner and carrier (JP-A-4-24651). Further, a means for obtaining a dry two-component type developer having a stable charge amount even if it is used for a long time or the use environment changes (Japanese Patent Laid-Open No. 62-295067) has been proposed.

That is, in Japanese Unexamined Patent Publication No. 4-24651, in the production of the initial developer, the charge amount of the carrier and the toner is agitated and mixed to saturate the charge amount, and then the agitation and mixing are continued to change the charge amount of the initial developer. 65-90% of saturated charge
The adjustment is made so that a stable image can be formed from the initial stage of image formation through the image stabilization period. In Japanese Patent Laid-Open No. 62-295067, the charge amount is changed by subjecting a carrier and / or a toner to a humidity control process even if the environment in mixing the carrier and the toner is changed and the developer is used for a long time. The present invention provides a dry two-component type developer which is stable or has little change.

[0004]

However, in the conventional dry two-component type developer, there are many problems in the actual image quality from the initial stage of image formation to the stable period of image formation, especially in the initial stage of image formation. However, there is a problem that the image is unstable due to transferability, fixability, fog and toner scattering.
An object of the present invention is to provide a dry two-component developer capable of always forming an image stably from the initial stage of image formation to the stable period of image formation.

[0005]

According to the present invention, in a dry two-component developer comprising a carrier and a toner, the replenishment toner has a shape factor of 55 to 85%, and the initial developer has a toner shape factor of 5 to 1 from the shape factor of replenishment toner
It is characterized by being 0% higher. The toner of the initial developer is preferably obtained by stirring and mixing the carrier and the toner in the range of the glass transition temperature of the binder resin from -30 ° C to + 10 ° C. The "shape factor" of the toner in the present invention is defined as follows. The “particle specific surface area” of the denominator is measured by an air permeation type specific surface area measuring device (WTY-2 manufactured by Sankyo Denki Co., Ltd.). This measurement is a method in which a sample is filled in a measuring cell to allow air to permeate, and the specific surface area of the powder is determined based on the pressure loss at that time.The specific surface area depends on the porosity of the toner layer filled in the cell. To do. Here, the specific surface area was determined by unifying the porosity to 50%. The "specific surface area of a sphere having the same volume as a particle" of a molecule is measured by a Coulter counter (RTA = II).

The shape factor of the toner indicates the sphericity of the particles, which is determined by the toner manufacturing method. When the method of colliding the toner kneaded material with the collision plate by air flow type pulverization or the like is adopted, the shape factor becomes small, and for example, mechanical fine pulverization such as Kawasaki Heavy Industries Kryptron pulverizer is performed,
A toner having a relatively large shape coefficient can be obtained by subjecting to hot air treatment after pulverization or treatment by an impact method in a high-speed air stream.
Further, if it is manufactured by a polymerization method, an almost spherical toner can be obtained.

Next, the toner material and carrier particles will be described. (1) As the binder resin for the toner material, 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-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate) Copolymers, styrene-butyl methacrylate copolymers, styrene-phenyl methacrylate copolymers, etc.), styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers, etc. Resin (styrene or homopolymer or copolymer containing styrene substitution product), vinyl chloride resin,
Rosin-modified maleic acid resin, phenyl resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral and the like, Particularly preferably used are polyester or styrene resins.

(2) As a colorant for the toner material, an example of a colorant for black: carbon black Spirit black Aniline black (CIPigment Brack 1) An example of a colorant for yellow: CIPigment Yellow 1 Symuler Fast Yellow GH CIPigment Yellow 3 Symuler Fast Yellow 10GH (manufactured by Dainippon Ink and Chemicals) CIPigment Yellow 12 Symuler Fast Yellow GF (manufactured by Dainippon Ink and Chemicals) Yellow 152 (manufactured by Arimoto Kagaku) Pigment Yellow GRT (manufactured by Arimoto Kagaku) Sumika Dye Co., Ltd.) Sumika Print Yellow ST-0 (Sumitomo Chemical Co., Ltd.) Benzidine Yellow 1316 (Noma Chemical Co., Ltd.) Seika Fast Yellow 2300 (Dainichi Seika Co., Ltd.) Lionol Yellow GRT (Toyo Ink Co., Ltd.) CI Pigment Yellow 13 Symuler Fast Yellow GRF (manufactured by Dainippon Ink and Chemicals, Inc.) CIPigment Yellow 14 Symuler Fast Yellow 5GR (manufactured by Dainippon Ink and Chemicals, Inc.) CIPigment Yellow 17 Symuler Fast Yell ow 8GR (Dainippon Ink and Chemicals Incorporated) Example of magenta coloring material: CIPigment Red 81 Symulex Rhodamine Y Tanex F (Dainippon Ink and Chemicals Incorporated) CIPigment Red 122 CIPigment Red 57 Symuler Brill Carmine 6B (Dainippon Ink and Chemicals) Industrial Co., Ltd.) CI Pigment Red 22 Symuler Fast Brill Scarlet BG
(Manufactured by Dainippon Ink and Chemicals, Inc.) CI Pigment Red 21 Sanyo Fast Red GR
(Made by Sanyo Dye Co., Ltd.) CI Pigment Red 18 Sanyo Toluidine Maroon Medium
(Manufactured by Sanyo Dye Co., Ltd.) CIPigment Red 114 Symuler Fast Carmine BS (manufactured by Dainippon Ink & Chemicals Co., Ltd.) CIPigment Red 112 Symuler Fast Red FGR (manufactured by Dainippon Ink and Chemicals Co., Ltd.) CIPigment Red 5 Symuler Fast Carmine FB (Dainippon Ink Chemicals) An example of a coloring material for cyan: CIPigment Blue 15 Fastogen Blue (manufactured by Dainippon Ink and Chemicals, Inc.) Chramofine SR (manufactured by Dainichiseika) CIPigment Blue 16 Sumitone Cyanine Blue LG
(Manufactured by Sumitomo Chemical Co., Ltd.) CIPigment Green 7 Phthalocyanine Green (manufactured by Toyo Ink Co., Ltd.) 36 Cyanine Green 2YL (manufactured by Toyo Ink Co., Ltd.) CIPigment Blue 15: 3 Cyanine Blue GGK (manufactured by Nippon Pigment Co., Ltd.) and the like. The amount of the colorant in the toner is preferably 0.1 to 15 parts by weight, more preferably 0.1 to 9 parts by weight, based on 100 parts by weight of the binder resin.

(3) A charge control agent is generally contained in the toner, specifically, nigrosine dye, chromium-containing complex, quaternary ammonium salt and the like are used. These are selected depending on the polarity of the toner particles. To be In the case of a color toner, a colorless or light color toner that does not affect the color tone of the toner is preferable, and examples thereof include a metal salt of salicylic acid or a metal salt of a salicylic acid derivative (Bontron E84, manufactured by Orient Chemical Co., Ltd.). The amount of charge control agent is 100
0.1 to 10 parts by weight, more preferably 0.
2 to 7 parts by weight is suitable.

(4) Further, a fluidity-imparting agent may be added to the obtained toner particles (either internal addition or external addition is preferable, but external addition is more preferable). As a fluidity-imparting agent,
Fine particles of metal oxides such as silica, alumina, magnesia, zirconia, ferrite, magnetite, etc., and silane coupling agents, titanate coupling agents, zircoaluminates, quaternized ammonium salts, fatty acids, fatty acid metal salts, fluorine-based Those which have been surface-treated or coated with a treatment agent such as an activator, a solvent, a polymer, fine particles of a fatty acid such as stearic acid or zinc starate or a metal salt thereof, and those obtained by surface-treating these fine particles with the treatment agent, polystyrene, poly. Methyl methacrylate,
Polymer fine particles such as polyvinylidene fluoride, and those obtained by surface-treating or coating these fine particles with the above-mentioned treatment agent are used. The average particle size of these fluidity-imparting agents is 0.01 to
Those in the range of 3 μm are used. The amount of the fluidity-imparting agent added is 0.1 to 100 parts by weight of the toner particles.
It is preferably in the range of 7.0 parts by weight, particularly 0.2 to 5.0 parts by weight. The mixing method of the toner particles and the fluidity-imparting agent is to move the powder in a fluid state at high speed by an air flow or mechanical force,
Substantially no grinding occurs. As the mixer, a high-speed flow type mixer, for example, a Henschel mixer,
For example, a UM mixer.

As the method for producing the toner according to the present invention, various known methods or a combination thereof can be used. For example, in the kneading and pulverizing method, a binder resin, a coloring material such as carbon black, and necessary additives are dry-kneaded, and heat-melted and kneaded by an extruder, a two-roll roll, a three-roll roll, or the like, and after cooling and solidification. A toner is obtained by pulverizing with a pulverizer such as a jet mill and classifying with an air stream classifier. It is also possible to directly produce a toner from a monomer, a colorant, and an additive by a suspension polymerization method or a non-aqueous dispersion polymerization method.

On the other hand, the carrier generally has a carrier core material coated with a releasing resin. As an example of the carrier core material, iron powder, oxidized iron powder, ferrite, nickel, or other magnetic material can be used. The particle size of the core substance is 20 to 11
0 μm, preferably about 30 to 90 μm is suitable.

As the releasing resin for carrier coating, a polyolefin resin such as polyethylene,
Polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin (eg polymethylmethacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylcarbazole, Polyvinyl ethers and polyvinyl ketones; vinyl chloride-vinyl acetate copolymers; styrene-acrylic acid copolymers; silicone resins such as straight silicone resins composed of organosiloxane bonds or modified products thereof (for example, alkyd resins, polyester resins, epoxy resins). , Modified products with polyurethane resin, etc.); Fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorine Trifluoroethylene; polyamides; polyesters such as polyethylene terephthalate; polyurethanes; Porika phosphonate; amino resins such as urea - formaldehyde resins, epoxy resins and the like. Of these, acrylic resins, silicone resins or modified products thereof, and fluororesins, particularly silicone resins or modified products thereof, are preferable from the viewpoint of preventing the spent toner from adhering to the carrier. In addition, as a commercially available product of silicone resin (however, straight silicone resin), KR27 manufactured by Shin-Etsu Chemical Co., Ltd.
1, KR255, KR251, SR2400, SR2406 manufactured by Toray Silicone Co., Ltd., and modified silicone resins KR206 (alkyd resin modified product), KR3083 (acrylic resin modified product) and ES1001N (epoxy resin modified) manufactured by Shin-Etsu Chemical Co., Ltd. Products), SR2115 (epoxy resin modified product) and SR2110 (alkyd resin modified product) manufactured by Toray Silicone Co., Ltd. The amount of the release resin used is 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, per 100 parts by weight of the carrier core material.

A conductive substance may be added to the carrier coating layer. (A) Example of white conductive material: ECT-52 (TiO ₂ system) Titanium industry company KV400 (TiO ₂ system) Titanium industry company ECR-72 (TiO ₂ system) Titanium industry company ECTR-82 (TiO ₂₎ System) Titanium Industry Co., Ltd. 500W (TiO ₂ system) Ishihara Sangyo Co., Ltd. 300W (TiO ₂ system) Ishihara Sangyo Co., Ltd. S-1 (TiO ₂ system) Ishihara Sangyo Co., Ltd. W-1 (SnO ₂ system) Mitsubishi Metals Co., Ltd. 23K (ZnO) Hakusui Chemical Co., Ltd. Conductive Zinc Flower No. 1 (ZnO) Honjo Chemical Co., Ltd. Conductive Zinc Flower No. 2 (ZnO) Wonjo Chemical Co., Ltd. W-10 (TiO ₂ system) Mitsubishi Metals Co., Ltd. Tentor WK-100 (conductive fiber) Otsuka Chemical Co., Ltd. Tentor WK-200 (conductive fiber) Otsuka Chemical Co., Ltd. Tentor WK-300 (Conductive fiber) Otsuka Chemical Co., Ltd. MEC300 (SnO ₂ type) Teikoku Kako's MEC500 (SnO ₂ type) Teikoku Kako's (B) Carbon example: Black Pearls 2000, VULCANXC-72 (Cabot's) Ketjen black EC.DJ500, Ketjenblack EC.DJ600
(Lion Akzo) Denka black granular, Denka black powder (Denki Kagaku Kogyo) CONDUCTEX975, CONDUCTEX SC (Colombia Carbon Co.)

The amount of conductive material is, for example, silicon resin 10
0.05 to 70 parts by weight, more preferably 0.1 to 50 parts by weight, based on 0 parts by weight, and if necessary, to improve the adhesive strength of the coating layer, and further improve the dispersibility of the conductive substance Therefore, a silane coupling agent may be added to the coating layer. The coating layer can be formed on the surface of the carrier particles by a method such as a spraying method or a dipping method as in the conventional case.

The method of manufacturing the toner according to the present invention is as described above, but it should be noted that the shape factor of the toner of the initial developer is the shape factor of the replenishment toner (55 to 8).
5%) to be 5 to 10% higher. This can be obtained by once producing a toner and then mixing the toner and the carrier within the range of −30 ° C. to + 10 ° C. of the glass transition temperature (Tg) of the binder resin of the toner.

[0017]

EXAMPLES Next, the present invention will be described more specifically with reference to examples.

Example 1 100 parts by weight of binder resin (polyester resin, Tg = 62 ° C.) 4 parts by weight of charge control agent (zinc salicylate) 6 parts by weight of coloring material (carbon black) After thoroughly mixing with a blender , 120
Melt kneading was carried out by a two roll heated to ˜140 ° C.
The kneaded product was allowed to cool naturally, roughly crushed with a cutter mill, crushed with a fine crusher using a jet stream, and then a mother toner having a volume average particle size of about 8 μm was obtained using an air classifier. further,
1.0 part by weight of fine silica powder was added to 100 parts by weight of the base toner and mixed by a mixer to obtain a toner (shape factor: 58).
%). Its concentration (measured with a Macbeth densitometer, the same applies hereinafter) was 1.24. On the other hand, a coating liquid was prepared as a carrier coating material by the following formulation. Silicone resin liquid (solid content 20%) 300 parts by weight Toluene 1500 parts by weight Average particle size of about 5 in a rotating disk type fluidized bed particle coating device.
500 parts by weight of a 0 μm ferrite carrier was poured and the coating solution of the above formulation was sprayed under heating at 80 ° C., the coated product was taken out by a coating device, placed in a constant temperature bath and heated at 200 ° C. for 2 hours. The silicone film was cured to prepare a carrier.

Subsequently, 5 parts by weight of the toner and 95 parts by weight of the carrier were mixed in an atmosphere of 32 ° C. to prepare a dry two-component developer (initial developer). At this time, the shape factor of the toner was 67%. The concentration was 1.35. A cyclone suction device was used to separate the carrier and the toner. When this developer was put in a plain paper copying machine manufactured by Ricoh Co., Ltd., and an image was output, no image difference was observed from the beginning of image formation (0 to 2000 sheets) to the image formation stable period, which was a problem. And the fixing property were good, and neither fog nor toner scattering was observed. Further, when the image formation was carried out while the toner having the shape factor of 58% was added after the image formation stable period, a good quality copy was continuously obtained.

Example 2 A kneaded product having the same formulation as in Example 1 was naturally cooled, coarsely pulverized by a cutter mill, finely pulverized by using a Kryptron pulverizer manufactured by Kawasaki Heavy Industries, Ltd., and then an air classifier was used. Volume average particle size about 8
A base toner having a size of μm was obtained. Further, this mother toner 100
1.0 part by weight of silica fine powder was added to parts by weight and mixed by a mixer to obtain a toner (shape factor 78%). This concentration was 1.40. On the other hand, the same carrier as in Example 1 was prepared.

Subsequently, 5 parts by weight of the toner and 95 parts by weight of the carrier were mixed in an atmosphere of 32 ° C. to prepare a dry two-component type developer (initial developer). The shape factor of the toner at this time was 87%. The concentration was 1.56. The carrier and the toner were separated by the same method as in Example 1. When an image was formed using this two-component developer in the same manner as in Example 1, similar results were obtained.

Example 3 The same carrier and toner as in Example 1 were prepared. 5 parts by weight of these toners and 95 parts by weight of the carrier were mixed in an atmosphere of 70 ° C. to prepare a dry two-component developer (initial developer). The shape factor of the toner at this time is 67%
Met. The concentration was 1.32. The carrier and the toner were separated by the same method as in Example 1. When an image was formed using this two-component developer in the same manner as in Example 1, similar results were obtained.

Example 4 The same carrier and toner as in Example 1 were prepared. 5 parts by weight of these toners and 95 parts by weight of the carrier were mixed in an atmosphere of 70 ° C. to prepare a dry two-component developer (initial developer). The shape factor of the toner at this time is 85%
It came out. The concentration was 1.50. The carrier and the toner were separated by the same method as in Example 1. When an image was formed using this two-component developer in the same manner as in Example 1, similar results were obtained.

Comparative Example 1 A toner was prepared according to the same formulation as in Example 1 (however, the toner has a shape factor of 50% and a density of 1.10).
The carrier used was exactly the same as in Example 1. 5 parts by weight of these toners and 95 carriers
Part by weight was mixed in an atmosphere of 27 ° C. to prepare a dry two-component developer (initial developer). At this time, the shape factor of the toner was 57%. The concentration was 1.21.
The carrier and the toner were separated by the same method as in Example 1. When an image was formed using this two-component developer in the same manner as in Example 1, there was no difference in transferability and fixability at the beginning of image formation, which is a problem, but fog was observed from the initial stage. Occurrence of toner scatter was also seen.

Comparative Example 2 The same carrier and toner as in Example 1 were prepared. 5 parts by weight of these toners and 95 parts by weight of carrier were mixed in an atmosphere of 80 ° C. to prepare a dry two-component developer (initial developer). The shape factor of the toner at this time is 58%
Met. The concentration was 1.25. The carrier and the toner were separated by the same method as in Example 1. In addition,
Some toner was found to be molten. An image was formed using this two-component developer in the same manner as in Example 1. As a result, the image density was low overall, and in addition, fog and toner scattering were observed.

Comparative Example 3 A toner was prepared according to the same formulation as that of the example (however, the toner had a shape factor of 87% and a density of 1.56).
The same carrier as in Example 1 was prepared. 5 parts by weight of these toners and 95 parts by weight of a carrier were mixed in an atmosphere of 27 ° C. to prepare a dry two-component developer (initial developer). The toner shape factor at this time is 87%
Nevertheless, the concentration was 1.56. The carrier and the toner were separated by the same method as in Example 1. In addition, it took more manufacturing time than usual to increase the shape factor of the toner to this level. Example 1 using this two-component developer
When an image was formed in the same manner as in Example 1, the fixability was about the same as in Example 1, but fog and toner scattering were observed.

Comparative Example 4 The toner is the same as in Comparative Example 3, and the carrier is in Example 1.
I prepared the same ones as above. 5 parts by weight of these toners and 95 parts by weight of carrier were mixed in an atmosphere of 27 ° C. to prepare a dry two-component developer (initial developer). At this time,
Some toner was found to be molten. When an image was formed using this two-component developer in the same manner as in Example 1, the image density decreased as a whole.

[0028]

According to the first aspect of the present invention, by defining the toner shape (sphericity) in the initial developer from the beginning, a dry two-component system having good developing ability, fluidity and transferability can be obtained. A developer is obtained. According to the second aspect of the present invention, a good quality copy can be obtained without causing fog or toner scattering.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Chiharu Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. A dry two-component developer comprising a carrier and a toner, wherein the replenishment toner has a shape factor of 55 to 85.
%, And the shape factor of the toner of the initial developer is 5 to 10% higher than the shape factor of the replenishment toner, a dry two-component developer. 2. The toner of the initial developer is obtained by stirring and mixing a carrier and a toner in a range of a glass transition temperature of the binder resin from −30 ° C. to + 10 ° C. Dry two-component developer.