JPH0323909B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a magnetic brush development carrier used for developing electrostatic latent images in electrophotography and electrostatic recording. 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 is excellent in chargeability, surface contamination resistance, mechanical strength, adhesion between the core and the coating layer, etc. . Prior Art In 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 in terms of developer life, etc., various types of coated carriers have been developed and put into practical use. . There are various properties required for coat carriers, but particularly important properties include appropriate charging properties, impact resistance, abrasion resistance, good adhesion between the core and coating material, and uniform charge distribution. be able to. Considering the above-mentioned required characteristics, the coat carriers used in the past still have problems to be improved, and no perfect solution is known at present. 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 and 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 inventors of the present invention have conducted various studies and examinations in order 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 coat carrier. They have found that this is effective and have completed the present invention. SUMMARY OF THE INVENTION Accordingly, a principal object of the present invention is to provide a novel magnetic brush development carrier used for developing electrostatic latent images in electrophotography and electrostatic recording. Another object of the present invention is that since the charging rate is high and the surface contamination resistance is good, the amount of charging does not decrease during running, and as a result, there is no early fogging or internal contamination. Another object of the present invention is to provide a carrier for magnetic brush development that has excellent adhesion between the core material and the coating layer. Structure of the Invention The above and other objects of the present invention provide a polymer of monomers consisting of an ester of alcohol and methacrylic acid or acrylic acid having a fluorinated alkyl group on the core material, and a positively chargeable acrylic ester; This can be achieved by a positively charging electrophotographic carrier characterized in that it has a coating layer containing a polymer of a monomer selected from methacrylic acid ester or a nitrogen-containing vinyl monomer and is positively charging. As the monomer consisting of an ester of an alcohol having a fluorinated alkyl group and acrylic acid or methacrylic acid in the present invention, the following can be used. That is, 1, of acrylic acid or methacrylic acid.
1-dihydroperfluoroethyl, 1,1-dihydroperfluoropropyl, 1,1-dihydroperfluorohexyl, 1,1-dihydroperfluorooctyl, 1,1-dihydroperfluorodecyl, 1,
1-dihydroperfluorolauryl, 1,1,2,
2-tetrahydroperfluorobutyl, 1,1,
2,2-tetrahydroperfluorohexyl, 1,
1,2,2-tetrahydroperfluorooctyl,
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
-furopyl, 3-perfluorononyl-2-acetylpropyl, 3-perfluorolauryl-2-acetylpropyl, ruaminoethyl, 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 Examples include various ester compounds such as -N-butylaminoethyl. A monomer polymer consisting of an ester of an alcohol having a fluorinated alkyl group and acrylic acid or methacrylic acid is a homopolymer.
In addition to this, it may also be a copolymer, and the following can be used as such a copolymer component. Namely, styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene,
Alkyl styrenes such as diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, octyl styrene, halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene, as well as nitrostyrene and acetyl styrene. Styrenic monomers such as styrene and methoxystyrene; acrylic acid, methacrylic acid, α-ethyl acrylic acid, crotonic acid,
α-ethyl crotonic acid, α-ethyl crotonic acid,
Addition polymerizable unsaturated aliphatic monocarboxylic acids such as isocrotonic acid, tiglic acid, ungelic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid,
Addition-polymerizable unsaturated aliphatic dicarboxylic acids such as mesaconic acid, glitaconic acid, dihydromuconic acid: the addition-polymerizable unsaturated carboxylic acids and alcohols, such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, Alkyl alcohols such as heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, halogenated alkyl alcohols that partially halogenate these alkyl alcohols, methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol , esterified products with alkoxyalkyl alcohols such as ethoxypropyl alcohol and ethoxypropyl alcohol, aralkyl alcohols such as bexyl alcohol, phenylethyl alcohol and phenylpropyl alcohol, alkenyl alcohols such as allyl alcohol and crotonyl alcohol, etc. Preferred examples include acrylic acid alkyl esters, methacrylic acid alkyl esters, fumaric acid alkyl esters, and maleic acid alkyl esters; amides and nitriles derived from the above-mentioned addition-polymerizable unsaturated carboxylic acids; ethylene, propylene, butene, isobutylene, etc. aliphatic monoolefin; vinyl chloride, vinyl bromide, vinyl iodide, 1,2-dichloroethylene, 1,2-dibromoethylene, 1,2-diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, Halogenated aliphatic olefins such as 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, 3-methyl-2,4-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-vinylpyrrolidine, N-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl-
2-pyrrolidone, N-vinyl-2-piperidone,
Examples include nitrogen-containing vinyl monomers such as N-vinylcarbazole. As the positively chargeable monomer polymer used in combination with the fluorinated alkyl acrylate or fluorinated alkyl methacrylate polymer, at least one of acrylic acid ester, methacrylic acid ester, and nitrogen-containing vinyl monomer is used. Polymers are preferred. These can also be used by copolymerizing with each other. Specific examples of acrylic esters and methacrylic esters include acrylic acid or methacrylic acid and alcohols, such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol,
Alkyl alcohols such as nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, and partially alkoxylated versions of these alkyl alcohols, such as methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, and ethoxypropyl alcohol. and aralkyl alcohols such as alkoxyalkyl alcohols, 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-butenylpyridine, 4-pentylpyridine, N-vinylpiperidine, 4-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrohil, N-vinylpyrroline, N-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinylcarbazole, etc. Examples include nitrogen-containing vinyl monomers. Comprising various polymers mixed with a polymer or copolymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate and at least one type of polymer of acrylic acid ester, methacrylic acid ester, or nitrogen-containing vinyl monomer. Other coating materials may also be used. Specific examples include polymers (including copolymers) of the various addition-polymerizable monomers mentioned above, as well as polyamides, polyesters, polycarbonates, silicone resins, cellulose resins, and other condensation resins as long as their chargeability permits. Can be used. Examples of the core material used in the present invention include powders such as glass beads, aluminum powder, iron powder, iron oxide powder, carbonyl iron powder, magnetite, nickel, and ferrite. The particle size is used. The carrier particles of the present invention can be obtained by surface-treating the magnetic core material as described above with the polymer according to the present invention as described above, and forming a coating layer of the polymer 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, a method of immersing the core material in a solution obtained by dissolving a mixture of two or more of the above-mentioned polymers in an appropriate solvent, followed by removing the solvent, drying, and high-temperature baking; Alternatively, a method can be used in which the core material is suspended in a fluidized bed, the polymer solution is spray applied, and the core material is dried and baked at a high temperature. In these methods, high temperature baking treatment is not necessarily required. The coverage of the polymer is usually 0.05% of 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 any negatively chargeable toner that is generally used in electrophotography, which has a colorant dispersed in a binder resin, can be used. In order to obtain good positive chargeability, the amount of the positively chargeable vinyl monomer polymer varies depending on the composition of the carrier coating amount and the composition of the toner, but in general, it is in the range of 30 to 98% by weight. It can be used in If it exceeds 98% by weight, surface stain resistance will deteriorate, and if it is less than 30% by weight, positive chargeability will decrease. Effects of the Invention According to the magnetic brush developing carrier of the present invention,
By coating the magnetic core material with a specific copolymer, it is possible to achieve the following various effects. The present invention is a polymer of a polymer consisting of an ester of an alcohol having a fluorinated alkyl group and methacrylic acid or acrylic acid, and a monomer selected from positively chargeable acrylic esters, methacrylic esters, or nitrogen-containing vinyl monomers. Since the carrier has a coating layer containing , the rate of increase in positive charge is high, and effects such as a small decrease in charge amount over a long period of time can be obtained. First, the rate of increase in positive charge is high and the amount of charge does not decrease during running, so there is no early fogging or internal contamination, and the adhesion between the core material and the coating is excellent (the coating layer (no peeling due to internal destruction), high mechanical strength,
In addition, since toner contamination is suppressed based on the low surface energy material coating, the life of the carrier and the life of the developer can be extended. It can be manufactured using a simple process. 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 40 parts by weight of N-perfluorohexylsulfonyl-N-butylaminoethyl acrylate, styrene
2 parts by weight of a polymer consisting of 20 parts by weight, 30 parts by weight of methyl methacrylate, 8 parts by weight of butyl acrylate, and 2 parts by weight of methacrylic acid, and 8 parts by weight of a polymer consisting of 85 parts by weight of methyl methacrylate and 15 parts by weight of styrene. Two types of polymers were dissolved in 100 parts by weight of toluene, and this solution was mixed with 1500 g of spherical iron oxide powder with an average particle size of 100 μm using a fluidized bed coating device.
The weight part was coated to obtain a carrier according to the present invention. Example 2 Polymer 2 consisting of 60 parts by weight of N-perfluorooctylsulfonyl-N-propylamine ethyl methacrylate and 40 parts by weight of methyl methacrylate
parts by weight, 90 parts by weight of methyl methacrylate, 7 parts by weight of dibutyl fumarate, and 3 parts by weight of vinylcarbazole.
A carrier according to the present invention was obtained using exactly the same procedure as in Example 1 using 12 parts by weight of two types of polymers. 1000 parts by weight of each of the carriers obtained in Examples 1 and 2 and 30 parts by weight of a negatively chargeable toner (consisting of a styrene-butyl acrylate copolymer, carbon black, and a chromium complex dye charge control agent) were mixed to form a developer. Prepared. When these developers were subjected to continuous copying tests using Fuji Xerox 4370, the following results were obtained.

[Table] Comparative Example 1 10 parts by weight of a polymer consisting of 85 parts by weight of methyl methacrylate and 15 parts by weight of styrene was dissolved in 100 parts by weight of methyl ethyl ketone, and this solution was coated into spheres with an average particle size of 100 μm using a fluidized bed coating device. A comparative carrier was obtained by coating 2000 parts by weight of iron oxide powder.

【table】

Claims (1)

[Claims] 1. A monomer selected from a monomer polymer consisting of an ester of an alcohol and methacrylic acid or acrylic acid having a fluorinated alkyl group on the core substance, and a positively chargeable acrylic ester, methacrylic ester, or nitrogen-containing vinyl monomer. 1. A positively chargeable electrophotographic carrier, characterized in that it has a coating layer containing a polymer.