JPH09319160A - Electrostatic latent image developing carrier, developer, image forming method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase adhesion property between a core particle and a coating layer and to suppress contamination of a toner component on a carrier by costing the core particle of the carrier with a coating resin containing a minute amt. of polyfluoroalkyl silasesquioxane in a resin. SOLUTION: This carrier has a resin coating layer containing a resin expressed by the formula on a core material. In the formula, (n) is an integer of 1 to 50, (m) is an integer of 0 to 98, (2n+1-m) is an integer of >=3, and (i) is an integer of 2 to 500. The amt. of the polyfluoroalkyl silasesquioxane in the rein coating layer is preferably 0.4 to 95wt.%, and more preferably 0.8 to 95wt.%. the mol.wt. of the resin is preferably 800 to 100000, and more preferably 1000 to 15000. The compounding ratio of the coating resin is preferably 0.1 to 5.0wt.%, more preferably 0.3 to 3.0wt.% of the whole carrier so as to balance the picture quality, secondary defects and electrification charge/property.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carrier for developing an electrostatic charge image, which is used when an electrostatic charge image formed by an electrophotographic method, an electrostatic recording method or the like is developed with a two-component developer, and the carrier is used. The present invention relates to a developer, an image forming method, and an image forming apparatus.

[0002]

2. Description of the Related Art A method of visualizing image information through an electrostatic charge image such as an electrophotographic method is currently used in various fields. In the electrophotographic method, an electrostatic latent image is formed on a photoconductor by a charging and exposing process, the electrostatic latent image is developed with a developer containing toner, and it is visualized through a transferring and fixing process. The developer used here is a two-component developer consisting of toner and carrier,
There is a one-component developer such as a magnetic toner that is used by itself as a toner, but in a two-component developer, the carrier shares functions such as stirring, transporting, and charging of the developer, and the functions are separated as the developer. It is easy to control the characteristics and is widely used at present.

In particular, a developer using a carrier coated with a resin is excellent in charge controllability, and it is relatively easy to improve environmental dependency and stability with time. Ferrite, which is lightweight and has excellent fluidity and controllability of magnetic properties, is often used as the core particles of the carrier. Further, as a developing method, a cascade method or the like has been used for a long time, but at present, a magnetic brush method using a magnetic roll as a developer carrying carrier is mainly used.

[0004] The magnetic brush method using a two-component developer includes:
There are problems such as occurrence of uneven image density due to charge deterioration of the developer, remarkable occurrence of stain on the background portion, and further decrease of image density. The charge deterioration of the two-component developer is because the toner component adheres to the carrier coat layer and gradually adheres to the carrier coat layer, which lowers the charging ability of the carrier and prevents sufficient triboelectric charging.

Therefore, a method has been proposed in which inorganic fine particles are attached to the toner surface and used as an external additive to reduce the contact area between the toner and the carrier and reduce the adhesive force between the toner and the carrier. Since the inorganic fine particles as the external additive adhere to the surface of the carrier coat layer and firmly adhere to each other, the deterioration of the image quality due to the deterioration of the charging ability of the carrier cannot be avoided.

Further, there has been proposed a method of forming a carrier coat layer using a resin material having a small surface energy in which a toner component is hard to adhere. However, this method is effective for the contamination of the toner component on the carrier coat layer, but since the resin having a small surface energy has a small adhesion to the core material particles of the carrier, stirring by the inside of the developing machine causes There was a problem that the carrier coat layer peeled off.
As a result, sufficient triboelectrification does not occur, and the developer is electrostatically deteriorated. Then, there are problems that image density unevenness is generated, a background portion is heavily soiled, and the image density is lowered.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention solves the above problems, prevents the toner components from adhering to the carrier coat layer as the number of copies increases, and reduces the charging ability of the developer. (EN) It is intended to provide a carrier for an electrostatic image developer, a developer, an image forming method and an apparatus thereof, which can suppress the peeling of the carrier coat layer and at the same time maintain a good copy image quality.

[0008]

The present invention has succeeded in solving the above problems by adopting the following means. (1) A resin-coated carrier characterized in that a resin coating layer containing a resin represented by the chemical formula (I) is provided on a core material. - _{[- Si (CH 3) (C} n F 2n + 1-m H m) -O- ] _i - (I) (wherein, n an integer of 1 to 50, m is an integer ranging from 0 to 98 , (2n + 1-m) is an integer of 3 or more, and i is 2 to 500.
Represents an integer in the range. )

(2) A resin which is not compatible with the resin represented by the chemical formula (I) and has a larger surface energy than the resin, and a resin coating layer containing the resin in the resin is used. The resin-coated carrier according to (1) above, which is provided. (3) The resin coating layer has a high concentration of the resin represented by the chemical formula (I) on its surface and a low concentration on the surface of the core material, according to the above (1) or (2). Resin coated carrier.

(4) The resin coating layer contains a resin containing the resin represented by the chemical formula (I) in an amount of 0.4 to 95% by weight. 3) The resin-coated carrier according to any one of 3). (5) The number average molecular weight of the resin represented by the chemical formula (I) is 80.
The above (1) characterized by being 0 to 100,000
The resin-coated carrier according to any one of (4).

(6) The resin coating amount is in the range of 0.1 to 5.0% by weight based on the weight of the carrier, according to any one of the above (1) to (5). Resin coated carrier. (7) The resin-coated carrier according to any one of (1) to (5) above, wherein the average particle diameter of the carrier is in the range of 20 to 150 μm.

(8) An electrostatic latent image developer comprising the resin-coated carrier according to any one of the above (1) to (7) and a toner. (9) The electrostatic latent image developer described in (8) above, wherein the average particle size of the toner is in the range of 3 to 9 μm.

(10) Using the developer layer on the developer carrier,
An image forming method for developing an electrostatic latent image on an electrostatic latent image carrier, which comprises using the developer according to (8) or (9) above. (11) An image forming apparatus comprising a developer carrier and an electrostatic latent image carrier, wherein the developer according to (8) or (9) is used.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the resin-coated carrier of a two-component developer, the present inventors have found that the resin represented by the above chemical formula (I) (hereinafter referred to as polyfluoroalkylsilsesquioxane) in the surface coating resin. It has been found that the above-mentioned problems can be achieved by containing the above-mentioned (), and the present invention has been completed.

As a cause of the image quality deterioration in the two-component developer system, there is a decrease in the charging ability of the carrier. Contamination of the toner component on the carrier surface is one of the causes of the decrease in the carrier charging ability. In order to charge the developer, mechanical agitation is performed in the developing machine, but stress at that time causes a weak portion (external additive or toner interface) in the structure of the toner to migrate to the carrier surface and contaminate it.
This toner component is mainly opposite in polarity to the charge of the carrier, and if it adheres to the surface of the carrier, the charging ability will be reduced. In order to avoid this decrease in charging ability,
By coating the carrier surface with a material having a small surface energy, the adhesion of toner components can be reduced. As a result, a decrease in charging ability can be suppressed.

However, peeling of the coating resin is mentioned as another cause of the deterioration of the carrier charging ability. This is a phenomenon in which the carrier coating resin itself is scraped off by stirring stress in the developing machine. Since the bonding force between the core particles and the coating resin is related to this, if a low surface energy material is used, peeling may cause a decrease in charging ability.

Therefore, in the present invention, the core material particles of the carrier are coated with the coating resin in which a trace amount of polyfluoroalkylsilsesquioxane is contained in the resin having a relatively high surface energy to coat the core material particles. It is possible to improve the adhesion to the layer and at the same time suppress the contamination of the carrier of the toner component.

Although the reason for this is not clear, in the process of coating the core material particle surface with a resin containing a small amount of polyfluoroalkylsilsesquioxane, polyfluoroalkylsilsesquioxane molecules having a small surface energy are Since it is incompatible with the resin having a relatively high surface energy that constitutes the coating resin, it is deposited on the surface layer of the carrier coating, and a large amount of it is present on the carrier surface. As a result, the low surface energy characteristic of the polyfluoroalkylsilsesquioxane remarkably appears on the carrier surface in contact with the toner, and the adhesion and fixing of the toner component on the carrier surface is suppressed. On the other hand, between the coating resin layer and the core particles, there are not many polyfluoroalkylsilsesquioxane molecules, and there is a resin having a relatively high surface energy,
Adhesion is enhanced and peeling of the coating resin is suppressed. As a result, it is possible to suppress the image quality deterioration due to the deterioration of the charging ability.

The polyfluoroalkylsilsesquioxane used in the present invention is a condensate of unit molecules represented by the following chemical formula (I). - _{[- Si (CH 3) (C} n F 2n + 1-m H m) -O- ] _i - (I) wherein, n represents 1 to 50, preferably 1 to 30, more preferably 5 to 20 , M is 0 to 98, preferably 0 to 5
8, more preferably an integer of 8 to 28, (2n + 1-m)
Is 3 to 101, preferably 3 to 50, more preferably 3
~ 17, i is 2-500, preferably 2-20
It represents 0, more preferably an integer of 2 to 30.

The content of the polyfluoroalkylsilsesquioxane in the coating resin is preferably 0.4 to 95 wt%, more preferably 0.8 to 95 wt%. This is because if it is less than 0.4 wt%, the polyfluoroalkylsilsesquioxane cannot be sufficiently present on the carrier surface, and the effect of suppressing the adhesion and sticking of the toner component is reduced.

The polyfluoroalkylsilsesquioxane has a relatively large molecular weight,
It is necessary to exist as a small mass. If the molecular weight is too small, it seems that the sufficient adhesion and sticking suppression function does not work. This is because the release function of the fluoroalkyl group alone has an effect of preventing adhesion and sticking, but it is thought that the function is improved by the addition of a freely movable bond such as a silanol group, which is generated by condensation. To be Therefore, the molecular weight is preferably in the range of 800 to 100,000, more preferably in the range of 1,000 to 15,000.

In the resin-coated carrier of the present invention, the coating resin containing the polyfluoroalkylsilsesquioxane is not compatible with the polyfluoroalkylsilsesquioxane molecule and has a relatively higher surface energy than the molecule. Is preferably used. Specifically, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, monochlorotrifluoroethylene, monofluoroethylene, copolymers of vinyl-based fluorine-containing monomers such as trifluoroethylene; styrene such as styrene, chlorostyrene, and methylstyrene. Kinds; methyl methacrylate,
Α-Methylene aliphatic monocarboxylic acids such as methyl acrylate, propyl acrylate, lauryl acrylate, methacrylic acid, acrylic acid, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, and ethyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; Acrylonitrile,
Nitriles such as methacrylonitrile; vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine; vinyl ethers; vinyl ketones; ethylene, propylene,
Olefins such as butadiene; homopolymers of silicones such as methyl silicone and methyl phenyl silicone,
Alternatively, a copolymer can be used, and further polyesters containing bisphenol, glycol, etc. can also be used.

These coating resins are used alone or in combination of two or more, and then polyfluoroalkylsilsesquioxane is added and used. The coating resin may be coated with magnetic powder, carbon black, inorganic fine particles, a charge control agent, or the like.

The amount of the coating resin compounded is 0.1 to 5.0% by weight, preferably 0.3 to 3.
The range of 0% by weight is suitable for achieving both the image quality, the secondary obstacle and the chargeability. When the core material particles are used in the insulating magnetic brush developing method, it is preferable to use magnetic particles having a substantially spherical shape and having an average particle diameter of 20 to 150 μm, such as ferrite and iron oxide powder, but the conductivity When used in the magnetic brush development method, an amorphous shape may be used.

In the resin coating method of the core material particles of the present invention, a fluidized bed, a spray dryer, a heating type kneader, a heating type Henschel mixer, a UM mixer, a planetary mixer or the like can be used.

The toner of the present invention is composed mainly of a binder resin and a colorant. As the binder resin used,
Styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, acrylic Esters of α-methylene aliphatic monocarboxylic acids such as butyl acrylate, octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl methyl ether, vinyl ethyl ether , Vinyl butyl ether and other vinyl ethers; vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone and other vinyl ketones, and other homopolymers and copolymers.

Particularly typical binder resins are polystyrene, styrene / alkyl acrylate copolymer, styrene / alkyl methacrylate copolymer, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride. Examples thereof include acid copolymers, polyethylene and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

As the colorant, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, copper phthalocyan, malachite green oxalate, lamp black, rose bengal, C. I. Pigment Red 48: 1,
C. I. Pigment Red 122, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Yellow 9
7, C.I. I. Pigment yellow 12, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 and the like. Furthermore, in addition to the above-mentioned components, a charge control agent, a cleaning aid, an offset preventive agent, and a fluidity accelerator may be contained, if necessary.

[0029]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following explanation, all "parts" are "weight parts"
Means

(Preparation of Polyfluoroalkylsilsesquioxane) H (CH ₃ ) SiCl ₂ and CH ₂ ═CHC
₄ F ₉ was hydrosilylated and then hydrolyzed to obtain a cyclic trimer with KOH. The cyclic trimer was polymerized using an organic Li catalyst. The reaction temperature and time at that time were changed to obtain polyfluoroalkylsilsesquioxane having three kinds of molecular weights. Each number average molecular weight is about 1500, about 100
It was 0 and about 800.

(Coating Resin) The above polyfluoroalkylsilsesquioxane and a resin having a relatively large surface energy, dimethylaminoethyl methacrylate (Mn of about 300).
00) was adjusted as shown in Table 1 below.

[0032]

[Table 1]

(Preparation of Carrier) 100 parts of Cu—Zn—Fe ferrite core material (50 μm) was coated with the above polyfluoroalkylsilsesquioxane as shown in Table 1 below to obtain a coating resin dimethylaminoethyl methacrylate ( 0.5 parts of Mn of about 30,000) were mixed and dried with a kneader to obtain carriers of Comparative Example 1 and Examples 1 to 5 having a volume average particle diameter of about 50 μm.

(Preparation of Toner) Polyester Binder Resin (Terephthalic Acid / Bisphenol A, Mw = 10,000) 95 Parts Colorant (CI Pigment Red 57: 1) 5 Parts 5 Parts Biaxial Kneading The mixture was kneaded in a machine, pulverized and classified to obtain toner particles having a volume average particle diameter of about 7 μm. With respect to the toner particles, silicon oxide fine particles having a primary particle diameter of 40 nm as an external additive have a coverage of 20% of the total surface area, and titanium oxide fine particles having a primary particle diameter of 15 nm have a coverage of 40%.
And mixed with a Henschel mixer. After that, toner sieving is performed with a sieving machine having a mesh size of 45 microns,
A toner was prepared.

Here, the coverage f can be obtained by the following equation. f = √3 × Dt × σt × C × 100) / (2π × db ×
σb) (In the formula, Dt is the average particle diameter of the toner particles, σt is the specific gravity of the toner particles, db is the average particle diameter of the external additive, σb is the specific gravity of the external additive, and C is the addition ratio of the external additive (wt. %).)

(Developer) The toners of Comparative Example 1 and Examples 1 to 5 were prepared by mixing the above toner and the carriers of Comparative Example 1 and Examples 1 to 5 at a weight ratio of 5:95. .

(Copying Test) Using a copying machine (A-COLOR635 modified machine manufactured by Fuji Xerox Co., Ltd.), the developer of Examples 1 to 5 and the developer of Comparative Example 1 are used as a developing machine, and a toner is supplied. It was put in a paper and continuously copied 10,000 sheets and evaluated, and the results are shown in Table 2. The developing conditions are such that the photoconductor potential is -650 V, the latent image potential is lowered to -200 V by exposure, and the developing machine includes -500 V as a DC component, a frequency of 6.0 kHz as an AC component, and Vp-p 1.5 kV. A developing bias was applied.

[0038]

[Table 2]

Each characteristic in the table was judged according to the following criteria. The graininess was determined by making a limit sample, and the fog was visually determined. Graininess: G1 to G5 and G1 are the best. Acceptable level is G3 or lower. Fog: G1 to G5 and G1 are the best. Acceptable level is G2 or lower. Charging Ability of Developer in Developing Machine: O means 1/2 or more of the charging ability of the initial developer. Δ means ⅓ or more and less than ½ of the initial charging ability of the developer. X: Means less than 1/3 of the initial charging ability of the developer.

As described in Examples 1 to 5, the one to which polyfluoroalkylsilsesquioxane was added can have a good charge imparting ability even after 10,000 sheets of copying, resulting in image defects such as fog. Will not occur. Also,
Polyfluoroalkyl silsesquioxane having an added amount of 0.4% or more is advantageous in terms of fog.

[0041]

According to the present invention, by adopting the above-mentioned constitution, it is possible to prevent the toner component from adhering to the carrier coat layer due to the increase in the number of copies and to suppress the deterioration of the charging ability of the developer. Peeling of the carrier coat layer can be suppressed, and as a result, high quality copy image quality can be maintained for a long period of time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 9/10 354 362 (72) Inventor Masanori Ichimura 1600 Takematsu, Minamiashigara City, Kanagawa Fuji Xerox Co., Ltd. In the company

Claims (11)

[Claims] 1. A resin-coated carrier comprising a core material and a resin coating layer containing a resin represented by the chemical formula (I). - _{[- Si (CH 3) (C} n F 2n + 1-m H m) -O- ] _i - (I) (wherein, n an integer of 1 to 50, m is an integer ranging from 0 to 98 , (2n + 1-m) is an integer of 3 or more, and i is 2 to 500.
Represents an integer in the range. ) 2. A resin which is not compatible with the resin represented by the chemical formula (I) and has a larger surface energy than the resin, and a resin coating layer containing the resin. The resin-coated carrier according to claim 1, wherein the carrier is a resin-coated carrier. 3. The resin according to claim 1, wherein the resin coating layer has a high concentration of the resin represented by the chemical formula (I) on its surface and a low concentration on the surface of the core material. Coated carrier. 4. The resin coating layer according to claim 1, wherein the resin represented by the chemical formula (I) contains 0.4 to 98% by weight of the resin. Resin coated carrier. 5. The resin-coated carrier according to any one of claims 1 to 4, wherein the resin represented by the chemical formula (I) has a number average molecular weight of 800 to 100,000. 6. The resin-coated carrier according to claim 1, wherein the resin coating amount is in the range of 0.1 to 5.0% by weight based on the weight of the carrier. . 7. The average particle size of the carrier is 20 to 150 μm.
The resin-coated carrier according to any one of claims 1 to 6, which is in the range of m. 8. An electrostatic latent image developer comprising the resin-coated carrier according to claim 1 and a toner. 9. The electrostatic latent image developer according to claim 8, wherein the average particle diameter of the toner is in the range of 3 to 9 μm. 10. Using a developer layer on a developer carrier,
An image forming method for developing an electrostatic latent image on an electrostatic latent image carrier, wherein the developer according to claim 8 or 9 is used. 11. An image forming apparatus comprising a developer carrying member and an electrostatic latent image carrying member, wherein the developer according to claim 8 or 9 is used.