JPS6180161A - Electrophotographic carrier - Google Patents

Abstract

PURPOSE:To enhance adhesion between a magnetic core material and a coating layer and to improve electrostatic chargeability, resistance to surface stains, and mechanical strength by using a specified polymer for the coating material of the magnetic core material. CONSTITUTION:The magnetic core material is coated with a polymer of fluoroalkyl acrylate (FAA) or fluoroalkyl methacrylate (FMA), and the content of said fluorinated monomer unit is regulated to <=50wt% of the total coating material. When FAA or FMA is homopolymerized, a mixture with another coationg material is used, and when it is copolymerized, if needed, another coating material is added and in both cases, FAA or FMA unit content is regulated to <=50wt% of the total coating material. The coating of the magnetic core material with such coating materials permits adhesion between the core material and the coat, the 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, the present invention provides a carrier for magnetic brush development, which is composed of a magnetic core material and a coating resin layer and has excellent charging properties, surface stain resistance, mechanical strength, adhesion between the core and the coating layer, etc. be.

In conventional electrophotography, a photoconductive substance such as selenium is used as a photoreceptor, an electrical latent image is formed using various means, and a toner is transferred to the 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. has been done.

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 negatively charged and have problems in adhesion to the core, and acrylic polymers have poor mechanical strength, adhesion to the core, Although it is satisfactory in terms of positive chargeability, it is said that there is a problem in surface contamination 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 conventional drawbacks, and have found that the use of a specific coating material satisfies the required characteristics of the coat carrier. The present invention was found to be effective for improvement, and the present invention was completed.

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 charging speed is high and the surface contamination resistance is good, so there is no decrease in the amount of charging during running, and as a result, there is no early fogging or internal contamination. It is an object of the present invention to provide a carrier for magnetic brush development that has excellent adhesion between a core material and a coating layer.

These and other objects of the present invention can be achieved by coating the core material with a specific amount of a fluorinated alkyl acrylate or fluorinated alkyl methacrylate polymer.

That is, in the present invention, a core material is coated with a polymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate, and the total coating material is calculated as a monomer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate. It relates to a positively chargeable electrophotographic carrier characterized in that the amount of the electrophotographic carrier is 50% by weight or less.

The fluorinated alkyl acrylate or fluorinated alkyl methacrylate as the coating material (coating material) according to the present invention is used as a homopolymer or a copolymer. In the case of a monomer polymer, it is always used, or in the case of a copolymer, it is mixed with other coating materials, and in either case, fluorinated alkyl acrylate or fluorinated alkyl methacrylate is used. , calculated as a single substance, it is characterized by not more than 50% by weight of the total coating material. If the amount of the fluorinated alkyl acrylate or fluorinated alkyl methacrylate is less than 50% by weight, it cannot be used as a positively chargeable carrier, and other disadvantages such as extremely poor adhesion with the core material occur.

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

That is, 1.1-dihydroperfluoroethyl of acrylic acid or methacrylic acid, 1. l-dihydroperfluoropropyl, 11 l-dihydroperfluorohexyl, 1.1
-dihydroperfluorooctyl, 1.1-dihydroperfluorodecyl, 1.1-dihydroperfluorolauryl,
1.1,2.2-tetrahydroverfluoroticyl, l,
1,2゜2- te) Rahi) 'Rover Frollo + nru, l, l.

2.2-tetrahydroperfluorooctyl, 1°1.2
．． 2-tetrahydroverfluoroticyl, 1°1.2.2
-Tetrahydroperfluorolauryl, 1.1,2.2-
Tetrahydroperfluorostearate, 2.2, 3.3
-tetrafluoropropyl, 2.2,3,3,4.4-hexafluorobutyl, 1.1. ω-Trihydroperfluorohexyl, l.

1, ω-trihydroperfluorooctyl, l, LL, 3
, 3.3-hexafluoro-2-fluoropyl, 3-perfluorononyl-2-acetylpropyl, 3-perfluorolauryl-2-acetylpropyl, N-perfluorohexylsulfonyl-N-methylaminoethyl, N-perfluoro hexylsulfonyl-N-butylaminoethyl, N-
Perfluorooctylsulfonyl-N-methylaminoethyl, N-perfluorooctylsulfonyl-N-ethylaminoethyl, N-perfluorooctylsulfonyl-N-
Butylaminoethyl, N-perfluorodecylsulfonyl-N-methylaminoethyl, N/<-fluorodecylsulfonyl-N-ethylaminoethyl, N-perfluorodecylsulfonyl-N-7'thylaminoethyl, N-perfluoro Various ester compounds such as laurylsulfonyl-N-methylaminoethyl, N-perfluorolaurylsulfonyl-N-ethylaminoethyl, and N-perfluorolaurylsulfonyl-N-butylaminoethyl are mentioned.

As the component to be copolymerized with the fluorinated alkyl acrylate or fluorinated alkyl methacrylate, the following can be used.

Namely, styrene, methylstyrene, dimethylstyrene,
Alkylstyrenes such as trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene, fluorostyrene,
Styrenic monomers such as chlorostyrene, bromostyrene, dipromostyrene, iodostyrene, halogenated styrene, nitrostyrene, acetylstyrene, methoxystyrene; acrylic acid, methacrylic acid, α-
Addition polymerizable unsaturated aliphatic monocarboxylic acids such as ethyl acrylic acid, crotonic acid, α-methylcrotonic acid, α-ethylcrotonic acid, isocrotonic acid, tiglic acid, ungellic acid, maleic acid, fumaric acid, itaconic acid, citracone addition-polymerizable unsaturated aliphatic dicarboxylic acids such as mesaconic acid, curtaconic acid, dihydromuconic acid; addition-polymerizable unsaturated carboxylic acids and alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, methyl alcohol, amyl alcohol, hexyl Alcohol, alkyl alcohol such as heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, partially alkoxylated cholera alkyl alcohol,
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, especially acrylic acid alkyl esters, methacrylic acid alkyl esters (excluding methyl methacrylate)
), fumaric acid alkyl esters, maleic acid alkyl esters, etc. are preferred examples; amides and nitriles derived from the above-mentioned addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene, and isobutylene; vinyl chloride , vinyl bromide, vinyl iodide, 1゜2-dichloroethylene, 1,2-dibromoethylene 7.1.2-short ethylene, impropenyl chloride,
Halogenated aliphatic olefins such as isopropenyl bromide, allyl chloride, allyl bromide, hnylidene 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 aliphatic diolefins 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-
Nitrogen-containing vinyl thread pickers such as vinyl-2-pyrrolidone, N-vinyl-2-piperidone, and N-vinyl-rubazole
can be exemplified. These can be used alone or in combination of two or more.

Examples of the coating material that can be used in combination with the polymer or copolymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate 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;
A particle size of 500μ is used.

The carrier particles of the present invention are obtained by surface-treating the core material as described above with the polymer (including copolymer) of the present invention as described above, and then applying the copolymer to the surface of the core material by chemical bonding or adsorption. It can be obtained by forming a coating layer of.

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 polymers in a suitable solvent, followed by desolvation, drying, and high temperature treatment. A method of baking, or a method of suspending the core material in a fluidized bed, spraying the polymer solution, drying, and baking at a high temperature can be used. In these methods, high temperature baking treatment is not necessarily required.

The amount of the polymer coated is usually 0.05 to 3% of the core material.
．． Preferably it is 0% by weight.

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

The toner is not particularly limited and may be any negatively chargeable 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 polymer.

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). (no peeling is observed), mechanical strength is high, and toner contamination is suppressed due to the low surface energy material coating, extending the life of the carrier and, in turn, the life of the developer. Alternatively, 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 N-perfluorooctylsulfonyl-N-methylaminoethyl methacrylate, 65 parts by weight of methyl methacrylate, and 15 parts by weight of styrene was dissolved in 100 parts by weight of methyl ethyl ketone, This solution was coated on 2,000 parts by weight of spherical iron oxide powder with an average particle size of 100 μm using a fluidized bed coating device, and then the carrier according to the present invention was coated.

Comparative Example 1 A control carrier was prepared in the same manner as in Example 1 except that 60 parts by weight of fluorinated alkyl methacrylate and 25 parts by weight of methyl methacrylate were used.

Comparative Example 2 A control carrier was obtained in the same manner as in Example 1 except that the use of fluorinated alkyl methacrylate was omitted and methyl methacrylate was changed to 85 parts by weight.

Example-2 1.1.2.10 parts by weight of a polymer consisting of 55 parts by weight of methacrylic acid ester of 2-tetrahydroperfluorodecyl alcohol, 44 parts by weight of methyl methacrylate, 1 part by weight of 4-vinylpyridine, and polymethyl 5 parts by weight of methacrylate were dissolved in 150 parts by weight of methyl ethyl ketone, and this solution was coated on 2000 parts by weight of ferrite powder having an average particle size of 60 μm using a fluidized bed coating apparatus to obtain a carrier according to the present invention.

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

Claims (1)

[Claims] A core material is coated with a polymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate,
A positively chargeable electrophotographic carrier, characterized in that the monomer accounts for 50% by weight or less of the total coating material.