JPS6180162A - Electrophotographic carrier - Google Patents

Abstract

PURPOSE:To enhance adhesion between a magnetic core material and a coating material and to improve electrostatic chargeability, resistance to surface stains, and mechanical strength by coating the core material with a specified polymer. CONSTITUTION:The magnetic core material is coated with a copolymer of fluoroalkyl acrylate or methacrylate and a positively electrifiable monomer, such as acrylate or methacrylate or an N-contg. vinyl monomer. Such a polymer coating material is sued, preferably, in an amt. of 0.05-0.3wt% of the core material, and a mixture with a toner is used as a magnetic brush developer. The coating of the magnetic core material with such a coating material permits adhesion between the core material and the coat, and mechanical strength to be both enhanced, and the use of it as a carrier permits charging speed to be enhanced, drop of the potential to be prevented in running, therefore, fogging at the early stage and stains inside the machine to be prevented, carrier surface stains due to a toner to be restrained, and thus, the life of a developer to be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to magnetic brush development carriers used for the development of electrostatic latent images in electrophotography and electrostatography. More specifically, it consists of a magnetic core material and a coating resin layer. The present invention provides a carrier for magnetic brush development that is excellent in charging properties, surface stain resistance, mechanical strength, adhesion between the core and the coating layer, and the like.

In conventional electrophotography, a photoconductive substance such as selenium is used as a photoreceptor, an electrical latent image is formed using various means, and toner is applied to this latent image using a magnetic brush development method or the like. A method of attaching and visualizing the image is generally adopted.

In this development process, carrier particles called carriers are used to impart an appropriate amount of positive or negative electricity to the toner. Carriers are generally classified into coated carriers and non-coated carriers, but since the former is superior when considering developer life, various types of coated carriers have been developed and put into practical use. It's there.

There are various characteristics required for coat carriers, but
Particularly important properties include appropriate chargeability, impact resistance, abrasion resistance, good adhesion between the core and coating material, and uniform charge distribution.
Examples include gender.

Considering the above required characteristics, the coat carriers used in the past still have problems that need to be improved.
No complete version is known at this time. For example, fluorinated vinyl polymers have excellent surface stain resistance, but are electrostatically charged and have problems in adhesion to the core, while acrylic polymers have mechanical strength, adhesion to the core, and electrostatic properties. Although it is satisfactory in terms of the following, it is said that there is a problem in surface stain resistance. In any case, the current situation is that we are forced to use coating materials that have advantages and disadvantages.

Purpose of the Invention In view of the current situation, the present inventors have conducted various studies and examinations to improve the various drawbacks of the conventional art, and have found that the use of a specific coating material can improve the various required characteristics of the coated carrier. The present invention has been completed based on the discovery that the method is effective in the following.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide a new magnetic brush development carrier used for developing electrostatic latent images in electrophotography and electrostatic recording.

Another object of the present invention is that the charge increase rate is high and the surface contamination resistance is good, so there is no decrease in the amount of charge during running, and as a result, there is no early fogging or contamination within the Kinki area. An object of the present invention is to provide a carrier for magnetic brush development that has excellent adhesion between a core material and a coating layer.

Structure of the Invention These and other objects of the invention are achieved by coating the core material with a copolymer of a fluorinated alkyl acrylate or fluorinated alkyl methacrylate and a positively chargeable monomer.

That is, the present invention provides a core material coated with a copolymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate and at least one of acrylic ester, methacrylic acid, and nitrogen-containing vinyl monomer. Relating to chargeable carriers.

The following can be used as the fluorinated alkyl acrylate or fluorinated alkyl methacrylate in the present invention.

That is, 1,1-dihydroperfluoroethyl acrylic acid or methacrylic acid, 1. l-dihydroperfluoropropyl, 1,1-dihydroperfluorohexyl, ■, 1-
Dihydroperfluorooctyl, 1. l-dihydroperfluorodecyl, 1,1-dihydroperfluorolauryl, 1
,1,2. ．． 2-tetrahydroperfluorobutyl, l,
1.2゜2-tetrahydroperfluorohexyl, l, 1
゜2.2-tetrahydroper70-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-propyl, 3-perfluorononyl-2-acetylpropyl, 3
-Perfluorolauryl-2-acetylpropyl, N-perfluorohexylsulfonyl-N-methylaminoethyl, N-perfluorohexylsulfonyl-N-butylaminoethyl, N-perfluorooctylsulfonyl-N-methylaminoethyl, N -Perfluorooctylsulfonyl-N-dithylaminoethyl, N-perfluorooctylsulfonyl-N-butylaminoethyl, N-perfluorodecylsulfonyl-N-methylaminoethyl, N-perfluorodecylsulfonyl-N-ethylamino Ethyl, N-
Perfluorodecylsulfonyl-N-butylaminoethyl, N-perfluorolaurylsulfonyl-N-methylaminoethyl, N-perfluorolaurylsulfonyl-N-ethylaminoethyl, N-perfluorolaurylsulfonyl-N-butylaminoethyl, etc. Examples include esterified products.

Suitable positively chargeable monomers include acrylic esters, methacrylic esters, and nitrogen-containing vinyl monomers.

Specific examples of acrylic esters and methacrylic esters include acrylic acid, methacrylic acid and alcohol,
Examples Eva, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol,
Alkyl alcohols such as hexyl alcohol, heftyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, which are partially alkoxylated versions of these alkyl alcohols, Examples include esterification products with alkoxyalkyl alcohols such as methoxypropyl alcohol and ethoxypropyl alcohol, aralkyl alcohols such as benzyl alcohol, phenylethyl alcohol and phenylpropyl alcohol, and alkenyl alcohols such as allyl alcohol and crotonyl alcohol.

Specific examples of nitrogen-containing vinyl monomers include 2-vinylpyridine, 4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butynylpyridine, 4-pentylpyridine, N -vinylpiperidine, 4-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole,
2-vinylpyrrole, N-vinylpyroline, N-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl-2-
Examples include pyrrolidone, N-vinyl-2-piperidone, and N-vinylcarbazole. These can be used alone or in combination of two or more.

The fluorinated alkyl acrylate or fluorinated alkyl methacrylate can be copolymerized with various monomers in addition to the positively chargeable monomer. Specific examples of other copolymerizable monomers include the following.

Namely, styrene, methylstyrene, dimethylstyrene,
Alkylstyrenes such as trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene, fluorostyrene,
Chlorostyrene, bromostyrene, dipromostyrene,
Halogenated styrenes such as iodostyrene, and styrenic monomers such as nitrostyrene, acetylstyrene, and methoxystyrene; α-ethyl acrylic acid, crotonic acid, α-methyl crotonic acid, α-ethyl crotonic acid, isocrotonic acid, tiglic acid, Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as ungellic acid; addition-polymerizable unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, dihydromucunic acid; unsaturated carboxylic acids and alcohols, e.g. evaporated methyl alcohol, ethyl alcohol,
Alkyl alcohols such as propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heftyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, and -S halogenated sitahalogenated alkyl alcohols ,
Methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, ethoxypropyl alcohol, aralkyl alcohol such as benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, alkenyl alcohol such as allyl alcohol, crotonyl alcohol Esterified products with alcohols, etc., amides and nitriles derived from the above-mentioned addition-polymerizable unsaturated carboxylic acids; ethylene, propylene,
Aliphatic monoolefins such as butene and isobutylene: vinyl chloride, vinyl bromide, vinyl iodide, l,2-dichloro, ethylene, 1,2-dibromoethylene, 1,2-short ethylene, isopropenyl chloride, isobromide Halogenated aliphatic olefins such as propenyl, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride, vinylidene fluoride: 1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-butadiene, 2 Conjugated diene aliphatic diolefins such as 3-dimethyl-1,3-butadiene, 2,4-hexadiene, and 3-methyl-2,4-hexadiene can be exemplified. These can be used alone or in combination of two or more.

Coating materials that can be used in combination with the fluorinated alkyl acrylate or fluorinated alkyl mechacrylate copolymer include various polymers. Specific examples include polymers and copolymers of the various addition polymerizable monomers mentioned above, as well as polyamides, polyesters, polycarbonates, silicone resins, cellulose resins, and other condensation polymer resins.

The core materials used in the present invention include glass peas, aluminum powder, iron powder, iron oxide powder, carbonyl iron powder,
Examples include powders such as magnetite, nickel, and ferrite, and usually 10 to 50
A particle size of 0 μm is used.

The carrier particles of the present invention are obtained by surface-treating the magnetic core material as described above with the copolymer according to the present invention as described above, and forming a coating layer of the copolymer on the surface of the core material by chemical bonding or adsorption. It can be obtained by

For surface treatment of the core material, for example, the core material is immersed in a solution obtained by dissolving one or more of the above-mentioned copolymers in a suitable solvent, followed by desolvation,
A method of drying and high-temperature baking, or a method of suspending the core material in a fluidized bed, spraying the copolymer solution, drying, and high-temperature baking can be used. In these methods, high temperature baking treatment is not necessarily required.

The amount of the copolymer coated is usually 0.05 to 0.05 to the core material.
Preferably it is 3.0% by weight.

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

The toner is not particularly limited and may be any negatively charged toner that has a colorant dispersed in a binder resin and is commonly used in electrophotography.

Effects of the Invention According to the carrier for magnetic brush development of the present invention, the following various effects can be achieved based on the fact that the magnetic core material is coated with a specific copolymer.

First of all, since the charging speed is high and the amount of charging does not decrease during running, there is no early fogging or contamination inside the machine, and the adhesion between the core material and the coating is excellent (internal destruction of the coating layer). It has high mechanical strength, and the surface energy resistant material coating suppresses toner contamination, extending the life of the carrier and the life of the developer. It can be manufactured by a simple process such as spray application of a solution or heat treatment if necessary.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these Examples in any way.

Example-1 10 parts by weight of a polymer consisting of 20 parts by weight of acrylic acid ester of 1,1,2,2-tetrahydroperfluorohexyl alcohol, 75 parts by weight of methylmequaacrylate, and 5 parts by weight of 2-vinylpyridine were mixed with 200 parts by weight of xylene. This solution was coated on 150 parts by weight of ferrite powder having an average particle size of 100 μm using a fluidized bed coating apparatus to obtain a carrier according to the present invention.

Example-2 10 parts by weight of a polymer consisting of 10ffi parts of methacrylic acid ester of 1, l, 2,2-tetrahydroperfluorohexyl alcohol, 89 parts by weight of ethylnucleate, and 1 part by weight of methacrylic acid were mixed into average particles. A carrier according to the present invention was obtained by coating 2000 parts by weight of spherical iron oxide powder with a diameter of 80 μm using the same procedure as in Example-1.

1000 parts by weight of each of the carriers obtained in Examples 1 and 2 and 30 parts by weight of a negatively charged toner (consisting of a styrene-butyl acrylate copolymer, carbon black, and a chromium complex dye charge control agent) were mixed and developed. A drug was prepared. When these developers were subjected to a continuous copying test using Fuji Xerox 4370, the following results were obtained.

Claims (2)

[Claims] (1) A positively chargeable electrophotographic carrier characterized by having a coating layer of a copolymer of a fluorinated alkyl acrylate or a fluorinated alkyl methacrylate and a positively chargeable monomer on a core material. (2) The positively chargeable monomer is an acrylic ester,
Claim No. 1 characterized in that it is at least one of methacrylic acid ester and nitrogen-containing vinyl monomer.
) The positively chargeable electrophotographic carrier described in item 1.