JPH0721651B2 - Carrier for developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic brush developing carrier used for developing an electrostatic latent image in electrophotography and electrostatic recording. Chargeability consisting of powder and binder resin,
The present invention relates to a carrier for magnetic brush development, which is excellent in surface stain resistance, mechanical strength, developer life, high-speed development property, and the like.

[Conventional technology]

In electrophotography, a photoconductive substance such as selenium is used as a photoconductor, an electric latent image is formed by various means, and a toner is attached to the latent image by a magnetic brush developing method or the like. A method of making the image visible is generally adopted.

In this developing step, carrier particles called carriers are used to give an appropriate amount of positive or negative electric charge to the toner. Various types of carriers have been developed and put into practical use.

[Problems to be solved by the invention]

Although there are various characteristics required for the carrier, suitable charging characteristics, impact resistance, abrasion resistance, developability, developer life, etc. can be mentioned as particularly important characteristics.

Considering the above required characteristics, the conventionally used carriers still have problems to be improved, and it is the actual situation that they are not sufficiently satisfactory. For example, conductive carriers such as iron oxide powder are excellent in solid developability but inferior in fine line reproducibility, and in order to extend the life, it is necessary to add a special charge control agent to the toner. On the other hand, although the coating type insulating carrier has a long life and excellent reproducibility of fine wires,
It has the drawback of poor solid reproducibility. A small particle size carrier in which magnetic fine particles are dispersed in a binder resin, a so-called microtoning carrier, has been proposed and put into practical use for the purpose of improving these drawbacks. Adhesion to the surface, change in charge at high humidity and low humidity, and difficulty in surface treatment make it impossible to prolong the life of the product.

Therefore, a main object of the present invention is to provide a novel magnetic brush developing carrier used for developing an electrostatic latent image in electrophotography, electrostatic recording and the like.

Another object of the present invention is that since the surface contamination resistance is good, the charge amount is not decreased during running, resulting in the early occurrence of fog and the in-machine contamination. An object is to provide a carrier for magnetic brush development having excellent properties.

[Means for solving problems]

The present inventors have conducted various studies and studies to improve the various drawbacks of the above-mentioned conventional carriers. As a result, a copolymer containing a fluorinated alkylacrylic monomer as a main component was used as a binder resin. The average particle size of magnetic particles dispersed in 60
When a carrier of μm to 200 μm is used, the image reproducibility (fine line reproduction) equivalent to that of the conventional small particle size carrier is not impaired, without losing the advantage of the large particle size carrier that the carrier does not adhere to the photoconductor. The present invention has been completed based on the finding that the () property is obtained.

That is, the present invention provides a carrier for a developer having an average particle size of 60 μm to 200 μm in which magnetic particles are dispersed in a binder resin containing a copolymer containing a fluorinated alkyl acrylic monomer as a monomer component. It was done.

The following can be used as the fluorinated alkyl acrylic monomer used for the binder resin of the carrier of the present invention.

That is, of acrylic acid or methacrylic acid, 1,1-dihydroperfluoroethyl, 1,1-dihydroperfluoropropyl, 1,1-dihydroperfluorohexyl, 1,1-dihydroperfluorooctyl, 1,1-dihydro Perfluorodecyl, 1,1-dihydroperfluorolauryl, 1,1,2,2-tetrahydroperfluorobutyl, 1,1,2,2-tetrahydroperfluorohexyl, 1,1,2,2-tetrahydroperfluoro Octyl, 1,1,2,2-tetrahydroperfluorodecyl,
1,1,2,2-tetrahydroperfluorolauryl, 1,1,2,2-
Tetrahydroperfluorostearyl, 2,2,3,3-tetrafluoropropyl, 2,2,3,3,4,4-hexafluorobutyl,
1,1, ω-trihydroperfluorohexyl, 1,1, ω-trihydroperfluorooctyl, 1,1,1,3,3,3-hexafluoro-2-chloropropyl, 3-perfluorononyl-2 −
Acetylpropyl, 3-perfluorolauryl-2-acetylpropyl, N-perfluorohexylsulfonyl-N
-Methylaminoethyl, N-perfluorohexylsulfonyl-N-butylaminoethyl, N-perfluorooctylsulfonyl-N-methylaminoethyl, N-perfluorooctylsulfonyl-N-ethylaminoethyl, N-
Perfluorooctylsulfonyl-N-butylaminoethyl, N-perfluorodecylsulfonyl-N-methylaminoethyl, N-perfluorodecylsulfonyl-N-ethylaminoethyl, N-perfluorodecylsulfonyl-N
-Butylaminoethyl, N-perfluorolaurylsulfonyl-N-methylaminoethyl, N-perfluorolaurylsulfonyl-N-ethylaminoethyl, N-perfluorolaurylsulfonyl-N-butylaminoethyl and the like ester compounds are mentioned. To be

The following can be used as the other monomer component copolymerized with the fluorinated alkyl acrylic monomer.

That is, styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, alkyl styrene such as octyl styrene, fluorostyrene, chlorostyrene, bromostyrene, Halogenated styrenes such as dibromostyrene and iodostyrene, styrene-based monomers such as nitrostyrene, acetylstyrene and methoxystyrene; acrylic acid, methacrylic acid,
Addition-polymerizable unsaturated aliphatic monocarboxylic acid such as α-ethyl acrylic acid, crotonic acid, α-methyl crotonic acid, α-ethyl crotonic acid, isocrotonic acid, tiglic acid, ungeric acid, maleic acid, fumaric acid, itaconic acid , Addition-polymerizable unsaturated aliphatic dicarboxylic acids such as citraconic acid, mesaconic acid, glutaconic acid and dihydromuconic acid; the addition-polymerizable unsaturated carboxylic acids and alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol,
Butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, and other alkyl alcohols, methoxyethyl alcohol, ethoxyethyl alcohol partially alkoxylated from these alkyl alcohols. , Alkoxyalkyl alcohols such as ethoxyethoxyethyl alcohol, methoxypropyl alcohol, ethoxypropyl alcohol, benzyl alcohol,
Esters with aralkyl alcohols such as phenylethyl alcohol and phenylpropyl alcohol, alkenyl alcohols such as allyl alcohol and crotonyl alcohol, especially alkyl acrylates, methacrylic acid alkyl esters (excluding methyl methacrylate), fumaric acid Preferred examples are alkyl esters, maleic acid alkyl esters, and the like; amides and nitriles derived from the addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene, and isobutylene; vinyl chloride, vinyl bromide. , Vinyl iodide, 1,2-dichloroethane, 1,2-dibromoethylene,
Halogenated aliphatic olefins such as 1,2-diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride, vinylidene fluoride; 1,3-butadiene, 1, 3-pentadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,
3-butadiene, 2,4-hexadiene, 3-methyl-2,4
-Conjugated diene-based aliphatic diolephin such as hexadiene; 2-vinylpyridine, 4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butenylpyridine, 4-pentylpyridine,
N-vinylpiperidine, 4-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrrole, N-vinylpyrroline, N-vinylpyrrolidine, 2-vinylpyrrolidine, N
Examples of the nitrogen-containing vinyl-based monomer include vinyl-2-pyrrolidone, N-vinyl-2-piperidone, and N-vinylcarbazole. These alone or 2
Combinations of more than one species can be used.

Examples of the material that can be used as a mixture with the fluorinated alkyl acrylic monomer polymer or copolymer include various polymers. Specific examples thereof include polymers of various addition-polymerizable monomers (including copolymers), polyamide, polyester, polycarbonate, silicone resin,
Cellulose resins and other polycondensation resins can also be used.

As the magnetic powder dispersed in the binder resin, any of those conventionally used as a magnetic material can be used.
For example, magnetite, gamma hematite, red iron oxide, chromium oxide, nickel, manganese, iron, cobalt, nickel alloy and the like can be mentioned. These magnetic powders have an average particle size of 0.
05μ to 5μ, preferably 0.1μ to 1μ. In addition, the ratio of the magnetic powder in all the components of the carrier is 30 to 95% by weight,
It is preferably 45 to 90% by weight.

Carriers composed of these magnetic powders and a binder resin can be manufactured by various methods. For example, a method of melting and kneading a resin and magnetic powder with a Banbury mixer, a kneader, a roll mill, an extruder, etc., cooling and pulverizing and classifying, or a method of mixing and dispersing magnetic powder in a resin solution, and then spray drying a spray drying method. Alternatively, a suspension polymerization method or the like in which a desired carrier is obtained by dispersing a predetermined material such as a monomer that constitutes the binder resin and a resin component in an appropriate solvent and polymerizing the suspension is suitable. It is possible.
Further, as a method for adjusting the particle size of the carrier, it can be adjusted by controlling the crushing conditions after melt-kneading, obtain a desired particle size by classification, or a plurality of different particle size distributions in advance. There is a method in which a carrier is prepared and mixed to obtain a carrier having a desired particle size distribution.

In the present invention, the carrier may be used as it is as carrier particles, but the carrier surface may be subjected to a surface treatment or a coating treatment with a resin, a coupling agent, an interfacial agent, a charge control agent, fine powder or the like.

Further, the carrier particles are preferably spherical particles that have been subjected to a spheroidizing treatment.

The carrier of the present invention has an average particle size of 60 μm to 200 μm in view of the adhesion of the carrier to the photoconductor and the balance of image quality.
More preferably, the thickness is 60 μm to 150 μm.

The carrier of the present invention thus obtained is mixed with toner and used as a magnetic brush developer for developing an electrostatic latent image.

As the toner, any toner in which a colorant is dispersed in a binder resin and which is commonly used in electrophotography can be used and is not particularly limited.

〔The invention's effect〕

In the carrier for magnetic brush development of the present invention, magnetic fine particles are used as a specific copolymer (fluorinated alkyl acrylic copolymer).
It is dispersed in the powder and is defined in a specific particle size range (50 μm or more), and various effects as described below can be obtained.

First, since the rate of charge rise is high and there is no reduction in the amount of charge during running, fogging does not occur early or contamination inside the machine does not occur, mechanical strength is high, and low surface energy material coating and low density are achieved. Based on the above, contamination by toner can be suppressed, so that the life of the carrier and thus the life of the developer can be extended, and further improvement in high-speed developability due to low magnetic permeability can be mentioned.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Methyl methacrylate / styrene / perfluorooctylethyl methacrylate (weight ratio 80/10/10) Copolymerization (weight average molecular weight about 30,000) 30 parts by weight and magnetic iron oxide fine powder 80
A part by weight was kneaded by heating and then pulverized.

Then, the mixture was allowed to stand in a dryer at 70 ° C. for 24 hours, and the obtained powder was sieved to obtain a carrier according to the present invention (Sample 1) having an average particle size of 80 μm and a particle size range of 53 to 150 μm.

This carrier is another known carrier, that is, an insulating carrier (CuZn ferrite core coated with the same copolymer as that of the example and having an average particle size of 90 μm: sample 2), a conductive carrier (average particle size). 100μ
m iron oxide powder: sample 3) and a magnetic fine particle-dispersed small particle size carrier (carrier having the same composition as in the example, having a mean particle size of 25 μm obtained by pulverizing and classifying a polymer and magnetic powder after melting and kneading: sample 4) It was evaluated as a developer.

A toner having an average particle size of 11 μm composed of styrene-acrylic resin and carbon black is used. Only the toner for the microtoning carrier has a toner concentration of 10% by weight, and the other carriers have a toner concentration of 3% by weight. To obtain a developer.

With regard to these developers, the initial charge amount, solid image density, background stain, fine line reproducibility, and adhesion of the carrier to the photoconductor at a photoconductor speed of 350 mm / sec and a developing magnetic roll (sleeve) speed of 550 mm / sec. , And the amount of charge when running 50,000 sheets, solid image density, background stain, and fine line reproducibility were evaluated, and tested under high humidity (30 ℃, 80% RH) and low humidity (10 ℃, 30% RH) environmental conditions. I went. The results are shown in the following table, and the superiority of the carrier according to the present invention was clarified.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikutaro Nagatsuka 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. Takematsu Office (56) References JP 61-5255 (JP, A)

Claims (1)

[Claims] 1. An average particle diameter of 60 μm to 200 in which magnetic fine particles are dispersed in a binder resin whose main component is a copolymer containing a fluorinated alkyl acrylic monomer as a monomer component.
μm developer carrier.