JPS6180163A - 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 coating material contg. a polymer of fluoroalkyl acrylate or methacrylate and a polymer of a positively electrifiable monomer, such as acrylate or methacrylate or an N-contg. vinyl monomer. 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, 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 charging properties, surface stain resistance, mechanical strength, adhesion between the core and the coating layer, etc. .

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 the former is more worrying when considering developer life, so various types of coated carriers have been developed and It has been put into practical use.

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 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 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 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 can be achieved by coating the core material with a polymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate and a polymer of a positively chargeable monomer. can.

That is, the present invention coats a core material with at least one of a polymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate, and a polymer of acrylic ester, methacrylic ester, and a nitrogen-containing vinyl monomer. The present invention relates to a positively chargeable carrier characterized by the following characteristics.

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

That is, 1.1-dihydroperfluoroethyl, 1.1-dihydroperfluoropropyl, 1.1-dihydroperfluorohexyl, ll of acrylic acid or methacrylic acid.
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. ω-trihydroperfluorohexyl, 1°1, ω-trihydroperfluorooctyl, 1.1°1.3,3.3-hexafluoro-2-furovir, 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-N-butylaminoethyl, and other ester compounds.

The fluorinated alkyl acrylate or the polymer of fluorinated alkyl acrylate may be used as a homopolymer or a copolymer, and the following copolymer components may be used: Can be done.

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, styrenic monomers such as nitrostyrene, acetylstyrene, and methoxystyrene; acrylic acid, methacrylic acid, α-
Addition polymerizable unsaturated aliphatic monocarboxylic acids such as ethyl acrylic acid, crotonic acid, α-ethyl crotonic acid, α-ethyl crotonic acid, isocrotonic acid, tiglic acid, ungellic acid, maleic acid, fumaric acid, itaconic acid, citracon Addition-polymerizable unsaturated aliphatic dicarboxylic acids such as mesaconic acid, glutaconic acid, dihydromuconic acid: the addition-polymerizable unsaturated carboxylic acids and alcohols, such as methyl alcohol, ethyl alcohol, propyl alcohol, methyl alcohol, amyl alcohol, hexyl Alkyl alcohols such as alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, these alkyl alcohols -i halogenated cytahalokenated alkyl alcohols, methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl Alcohol, ethoxypropyl alcohol, alkoxyalkyl alcohol such as ethoxypropyl alcohol, bequidyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, alkyl alcohol,
Preferred examples include esters with alkenyl alcohols such as allyl alcohol and crotonyl alcohol, particularly acrylic acid alkyl esters, methacrylic acid alkyl esters (excluding methyl methacrylate), fumaric acid alkyl esters, and maleic acid alkyl esters. ; Amides and nitriles derived from the above 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, 1,2-short ethylene, impropenyl chloride, impropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride , halogenated aliphatic olefins such as 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 diolefin 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-vinylvirol, N-vinylpyrroline, N-vinylpyrrolidine, 2-vinylpyrrolidine, N
Examples include nitrogen-containing vinyl monomers such as -vinyl-2-pyrrolidone, N-vinyl-2-piperidone, and N-vinylcarbazole.

As a polymer of a positively chargeable monomer used in combination with a polymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate, a polymer using at least one of acrylic acid ester, methacrylic acid ester, and nitrogen-containing vinyl monomer is used. is suitable. These can also be used by copolymerizing with each other.

Specific examples of acrylic esters and methacrylic esters include acrylic acid or methacrylic acid alcohols, such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, and nonyl alcohol. , dodecyl alcohol,
Alkyl alcohols such as tetradecyl alcohol and hexadecyl alcohol, partially alkoxylated versions of these alkyl alcohols, such as methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, and alkoxyalkyl alcohols such as ethoxypropyl alcohol; Examples include esterification products with 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-butenylpyridine, 4''''pentylpyridine, N -vinylpiperidine, 4-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrohil, N-vinylpyroline, N-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl-
Examples include nitrogen-containing vinyl monomers such as 2-pyrrolidone, N-vinyl-2-piperidone, and N-vinylcarbazole.

Other coating materials consisting of various polymers mixed with polymers or copolymers of fluorinated alkyl acrylates or fluorinated alkyl methacrylates and at least one type of polymer of acrylic esters, methacrylic esters, and nitrogen-containing vinyl monomers. You can also use 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.

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 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, e.g.
A method in which the core material is immersed in a solution obtained by dissolving a mixture of two or more species in a suitable solvent, followed by desolvation, drying, and high-temperature baking, or a method in which the core material is suspended in a fluidized bed and the A method of spraying a coalescing 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 thus prepared carrier of the present invention is mixed with a toner and used as a magnetic brush developer for developing electrostatic latent images.

As the toner, any negatively charged toner that is generally used in electrophotography, in which a colorant is dispersed in a binder resin, can be used, and the toner is not limited to the frame.

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, the charging speed is high and the amount of charging does not decrease during running, so there is no early fogging or internal contamination, and the adhesion between Core +4 and the coating is excellent (internal destruction of the coating layer). (no peeling is observed),
Due to the high mechanical strength and low surface energy material coating, toner contamination is suppressed, extending the life of the carrier and hence the life of the developer. It can be manufactured using a simple process such as heating.

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 Consisting of 40 parts by weight of N-perfluorohexylsulfonyl-N-7'f-aminomethyl acrylate, 20 parts by weight of styrene, 30 parts by weight of methyl methacrylate, 8 parts by weight of butyl acrylate, and 2 parts by weight of methacrylic acid. Two types of polymers, 2 parts by weight of a polymer and 8 parts by weight of a polymer consisting of 85 parts by weight of methyl methacrylate and 15 parts by weight of styrene, were dissolved in 10,000 parts by weight of toluene, and this solution was coated using a fluidized bed coating device. A carrier according to the present invention was obtained by coating 1,500 parts by weight of spherical iron oxide particles having an average particle size of 100 μm.

Example-2 2 parts by weight of a polymer consisting of 60 parts by weight of N-perfluorooctylsulfonyl-N-7'Cl pyramine ethyl methacrylate and 40 parts by weight of methyl methacrylate,
Using exactly the same procedure as in Example 1, two types of polymers, 12 parts by weight of a polymer consisting of 90 parts by weight of methyl methacrylate, 7 parts by weight of dibutyl fumarate, and 3 parts by weight of vinylcarbazole, were added to the carrier according to the present invention. I got it.

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. was prepared.

When these developers were subjected to a continuous copying test using Fuji Xerox 4370, the following results were obtained: 1st grade.

Claims (2)

[Claims] (1) Positively chargeable electrophotography characterized by having a coating layer on a core material containing a polymer of fluorinated alkyl acrylate or fluorinated alkyl methacrylate and a polymer of a positively chargeable monomer. carrier. (2) The positively chargeable monomer is at least one of acrylic esters, methacrylic esters, and nitrogen-containing vinyl monomers (
The positively chargeable electrophotographic carrier according to item 1).