JPS62295074A - Carrier for developer - Google Patents

Abstract

PURPOSE:To provide a titled carrier having an excellent developer life and high-speed developability by dispersing pulverized magnetic particles into a specific copolymer, providing a layer of a fluorinated alkyl acrylic polymer on the surface and specifying the same to a specific grain size range or above. CONSTITUTION:This carrier consists of the core which is formed by dispersing the pulverized magnetic particles into a binder essentially consisting of an acrylic copolymer and has 50-20mum, more preferably 60-150mum average grain size and the upper layer of the fluorinated alkyl acrylic polymer coating said core. The acrylic polymer used for the essential component of the core part of the carrier is a homopolymer or copolymer of an acrylate or methacrylate. A more specific example of the monomer constituting such acrylic polymer includes acrylic acid, etc., and a more specific example of the alcohol constituting the ester includes methyl alcohol, etc.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to an 8-brush developing device used for developing electrostatic latent images in electrophotography and electrostatic recording. A carrier, more specifically, a chargeable material consisting of a mother fine powder and a binder resin,
This invention relates to a carrier for magnetic brush development that is excellent in surface stain resistance, mechanical strength, developer life, high speed development, etc.

[Conventional technology]

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 method such as a brush development method. A method of attaching it and visualizing it 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. A seed-type carrier has been developed and put into practical use.

[Problem that the invention seeks to solve]

There are various properties required of the carrier, but particularly important properties include appropriate charging properties, impact resistance, abrasion resistance, developability, and developer life.

Considering the above-mentioned required characteristics, the carriers that have been used in the past still have problems that need to be improved, and no carrier that fully satisfies them is known at present. for example,
Conductive carriers such as iron oxide powder have excellent solid developability, but have poor fine line reproducibility, and have drawbacks such as the need to include a special charge control agent in the toner to extend life. On the other hand, although coated insulating carriers have excellent longevity and fine wire reproducibility, they have the disadvantage of poor solid reproducibility. In order to improve these drawbacks, 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. It has disadvantages such as adhesion to surfaces, charge change in high humidity and low humidity, and difficulty in surface treatment, which makes it impossible to drastically extend life.

Accordingly, a principal object of the present invention is to provide a novel magnetic brush development carrier for use in electrophotography and electrostatic recording for the development of electrostatic latent images.

Another object of the present invention is that 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 generation of capri and no contamination in the machine, and there is also a long developer life and high speed development. An object of the present invention is to provide a carrier for magnetic brush development with excellent properties.

[Means for solving problems]

As a result of various studies and examinations to improve the various drawbacks of the conventional carriers, the present inventors discovered that magnetic fine particles were dispersed in a binder resin mainly composed of an acrylic polymer with an average particle diameter of 50 μm. When using a carrier with a fluorinated alkyl acrylic copolymer as a surface layer on the above core,
We discovered that image reproducibility (fine line reproducibility) equivalent to that of conventional small-particle carriers can be obtained without losing the advantage of large-particle carriers in that they tend to stick to the photoreceptor, and this book was published. Completed the invention.

That is, the present invention consists of a core with an average particle diameter of 50 μm or more in which magnetic fine particles are dispersed in a binder resin mainly composed of an acrylic copolymer, and an upper layer of a fluorinated alkyl acrylic polymer covering the core. A carrier for developer is provided.

The acrylic polymer used as the main component of the core of the carrier according to the present invention is a homopolymer or copolymer of acrylic ester or methacrylic ester. Specific examples of monomers constituting these acrylic polymers Examples include the following compounds.

Specifically, examples include esters of acrylic acid and methacrylic acid with alkyl alcohols, halogenated alkyl alcohols, alkoxyalkyl alcohols, aralkyl alcohols, and alkenyl alcohols. Specific examples of the alcohol constituting the ester include methyl alcohol, ethyl alcohol, flobyl alcohol, methyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, and hexadecyl alcohol. Alkyl alcohols such as decyl alcohol; partially halogenated alkyl alcohols;
Chalkoxyalkyl alcohol such as methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, ethoxypropyl alcohol; 175 alkyl alcohol such as hensyl alcohol, phenylethyl alcohol, phenylethyl alcohol; allyl alcohol, crotonyl alcohol Examples include alkenyl alcohols such as

The above-mentioned acrylic monomers may be used alone or in combination of two or more, and if necessary, one or more of other copolymerizable monomers may be used. Also good. In this case, the acrylic monomer is 25% by weight of the total monomers, preferably 50%! It is desirable that f=1 or more.

Specific examples of other copolymerizable monomers include the following compounds.

That is, styrene and its derivatives, such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, flobylstyrene, methylstyrene, hexylstyrene,
Examples include alkylstyrenes such as heptylstyrene and octylstyrene, fluorostyrenes, chlorostyrenes, fluorostyrenes, cyphlomostyrenes, and halogenated styrenes such as iodostyrene, as well as nitrostyrene, acetylstyrene, methoxystyrene, and the like.

Also, polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, α-ethyl acrylic acid, crotonic acid, α-
Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as methyl crotonic acid, α-ethyl crotonic acid, incrotonic acid, tiglic acid, ungellic acid, or maleic acid, 7-malic acid,
Addition-polymerized and 11-unsaturated aliphatic silcarboxylic acids such as itaconic acid, citraconic acid, mesaconic acid, mertaconic acid, and dihydromuconic acid are mentioned.

Furthermore, metal salts of these carboxylic acids can also be used, and this metal salt formation can be carried out after the completion of polymerization.

Further, esterification products of the above-mentioned addition-polymerizable unsaturated carboxylic acids and alcohols such as alkyl alcohols, halogenated alkyl alcohols, alkoxyalkyl alcohols, aralkyl alcohols, and alkenyl alcohols may be mentioned.

Furthermore, amides and nitriles derived from the addition-polymerizable unsaturated carboxylic acid; ethylene, propylene, butene,
Aliphatic monoolefins such as inbutylene; vinyl chloride, vinyl bromide, vinyl iodide, 1.2-9 chloroethylene, 1.2-); f-romethylene, 1.2-short ethylene, isoproynyl chloride, isobromide propenyl, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride,
Halogenated aliphatic olefins such as vinylidene fluoride
L3-butadiene, 1,3-intadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-
butadiene, 2,4-hexadiene, 3-methyl-2,
Examples include conjugated diene aliphatic diolefins such as 4-hexadiene.

Further examples include vinyl acetates, vinyl ethers, and nitrogen-containing vinyl compounds such as vinyl carbazole, vinyl pyridine, and vinyl pyrrolidine.

As the fluorinated alkyl acrylic monomer for the fluorinated alkyl acrylic copolymer constituting the surface layer of the carrier according to the present invention, the following can be used.

i.e. 1,1-dihydronomo-70-loethyl, x, x-Q hydroperfluoropropyl, 1.1-s) hydroper-70-lohexyl of acrylic or methacrylic acid.
L l -Q hydroper 70 looctyl, 1.1-0 hydronose flororodecyl, 1.1-dihydroperfluorolauryl, 1,1,2.2-tetra b droper 70 butyl, 1.1.2.2- f-trahydrono-70-rohexyl, 1,1,2.2-tetrahydrono-70
looctyl, 1,1,2.2-tetrahydropa-90 perfluorodecyl, 1,1,2,2-tetrahydropa-70 lolauryl, 1,1,2,2-tetrahydropa-70 rostearyl, 2.2.3 .3-tetrafluoropropyl, 2
, 2°3, 3.4.4-hexafluorobutyl, 1.1.
ω-Tricht 0 lonosafe lorohexyl, 1,1. ω-
) IJ Hiro Nono-70 Looctyl, 1.1.1.3.
3.3-hexafluoro-2-70J all, 3-par 70
Lononyl-2-acetylpropyl, 3-per70 lolauryl-2-acetylpropyl, N-nozo-fluorohexylsulfonyl-N-methylaminoethyl, N-per70
lohexylsulfonyl-N--ethylaminoethyl, N
-perfluorooctylsulfonyl-N-methylaminoethyl, N-nomo70octylsulfonyl-N-xf
N-per70 lodecylsulfonyl-N-7' tylaminoethyl, N-per70 lodecylsulfonyl-N-methylaminoethyl, H-, t-70 lodecylsulfonyl-N-xf tylaminoethyl, N- 70 Rodecylsulfonyl-N-, methylaminoethyl,
H-, t'-70 lolaurylsulfonyl-N-methylaminoethyl, N-per70 lolaurylsulfonyl-N-
Various ester compounds such as ethylaminoethyl and N-per70loracrylsulfonyl-N-ethylaminoethyl can be 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, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, flobylstyrene, methylstyrene, hexylstyrene, heptylstyrene, alkylstyrene such as octylstyrene, 70rostyrene, chlorostyrene thromostyrene. , halogenated styrenes such as cyfuromostyrene, iodostyrene, styrenic monomers such as dinitrostyrene, acetylstyrene, methoxystyrene; acrylic acid, methacrylic acid,
Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as α-ethyl acrylic acid, crotonic acid, α-methylcrotonic acid, α-ethylcrotonic acid, isocrotonic acid, tiglic acid, ungellic acid, maleic acid, fumaric acid, itaconic acid , addition polymerizable unsaturated aliphatic dicarboxylic acids such as citraconic acid, mesaconic acid, glutaconic acid, dihydromuconic acid; addition polymerizable unsaturated carboxylic acids and alcohols, such as hamethyl alcohol, ethyl alcohol, flobyl alcohol,
Alkyl alcohols such as methyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dotecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, and partially alkoxylated versions of these alkyl alcohols, such as methoxyethyl alcohol and ethoxyethyl Alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, ethoxypropyl alcohol/l/ :I-
k'11,! l” noflukoxyalkyl alcohol, benzyl alcohol, phenylethyl alcohol,
Preferred examples include aralkyl alcohols such as phenylpropyl alcohol, allyl alcohol, and alkenyl alcohols such as crotonyl alcohol, particularly acrylic acid alkyl esters, methacrylic acid alkyl esters, fumaric acid alkyl esters, and maleic acid alkyl esters. 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-dichloroethylene, 1. z-dichloroethylene, 1,z-1 iodoethylene, inpropenyl chloride,
Halogenated aliphatic olefins such as isopropenyl bromide, 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-L3-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-vinylbiyridine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrrole, M-vinylpyroline, N-vinylpyrrolidine,
2-vinylpyrrolidine, N-vinyl-2-pyrrolidone,
Examples include nitrogen-containing vinyl monomers such as N-vinyl-2-piperidone and N-vinylcarbazole.

These can be used alone or in combination of two or more electric currents.

The magnetic particles used in the present invention can be any of the commonly used ferromagnetic particles, and specifically include triiron tetroxide, r-iron sesquioxide, various ferrite powders, ferric oxide, and various metals. The fine powder etc. is about 95% by weight, and preferably a blend of 45 to 90% by weight gives good table results.

The carrier particles of the present invention are produced by heating, kneading, and pulverizing magnetic fine particles and a binder resin containing an acrylic copolymer as a main component.
If necessary, heat and spheroidize the particles to obtain particles of the desired particle size, or dissolve the binder resin in a solvent that is soluble in the binder resin, mix it with magnetic fine particles to form a slurry, and then spray. It can be produced by a normal coating method of granulating and drying using a dryer, spheroidizing if necessary to obtain particles of the desired particle size, and then coating the particles with a fluorinated alkyl acrylic polymer. .

Further, the carrier particles of the present invention can also be produced without using a method of coating with a fluorinated alkyl acrylic polymer. In other words, fluorinated alkyl acrylic polymers have extremely low surface free energy, so acrylic polymers and magnetic fine particles are used.

A method in which a fluorinated alkyl acrylic polymer and a fluorinated alkyl acrylic polymer are heated, mixed, and then pulverized to form a spheroid, and an acrylic polymer and a fluorinated alkyl acrylic polymer are dissolved in a solvent, and magnetic fine particles are mixed therein to form a slurry. After that, the fluorinated alkyl acrylic polymer naturally comes out to the surface and forms a coating layer. Therefore, a desired two-layer structure carrier can be easily produced without requiring any special coating operation.

The carrier particles of the present invention have an average particle diameter of 50, from the viewpoint of the above-mentioned developer life, carrier adhesion to the photoreceptor, and image quality.
A suitable thickness is 200 .mu.m, preferably 60 to 150 .mu.m.

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

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 there is no particular limitation.

〔Effect of the invention〕

The carrier for magnetic brush development of the present invention has magnetic fine particles dispersed in a specific copolymer (acrylic polymer), a layer of fluorinated alkyl acrylic polymer is provided on the surface, and a specific particle size range (50 μm ) As specified above, various effects can be obtained as shown below.

First, since the charging rate is high and the amount of charging does not decrease during running, there is no early generation of capri or internal contamination, and it has high mechanical density and low surface energy. Due to the low density, contamination by toner is suppressed, thereby extending the life of the carrier and hence the life of the developer, and furthermore, high-speed development is improved due to the low magnetic permeability.

〔Example〕

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.

Methyl methacrylate/styrene = 80/20 (
30 parts by weight of a copolymer (weight average molecular weight: approximately 70,000) (weight ratio), 70 parts by weight of magnetic iron oxide fine powder, and N-par 70 lohexylsulfonyl-N-, / thylaminoethyl methacrylate / methyl methacrylate = A 10-fold strained part of a 4V60 (weight ratio) copolymer (weight average molecular weight about 5,000) is mixed with heat, pulverized, and classified. The obtained particles are processed using a thermal spheronization device to form spheroids and form multiple layers.

The obtained powder was sieved to obtain an average particle size of 85μ and a particle size range of 5.
Carrier according to the invention from 3 to 200 μm (sample 1)
I got it.

This carrier was replaced with another conventionally known carrier, namely an insulating carrier (CuZn ferrite core coated with the same copolymer as in the example).

Carrier with an average particle size of 90 μm: Sample 2), conductive carrier (iron oxide powder with an average particle size of 100 μm: Sample 3)
It was evaluated as a developer together with a magnetic fine particle dispersed small particle size carrier (carrier having the same composition as in the example, having an average particle size of 25 μm obtained by melt-kneading a polymer and magnetic powder, then crushing and classifying it: Sample 4).

The toner used was one consisting only of styrene-acrylic resin and carbon black with an average particle diameter of 11 μm. Only the microtoning carrier had a toner concentration of 10% by weight, and all other carriers had a toner concentration of 3%.
They were mixed in a proportion of % by weight to form a developer.

For these developers, photoreceptor speeds of 350 rary
'sec and developing magnetic roll (sleeve) speed 550
As tmA cost, initial charge amount, solid ° image density,
Background stains, fine line reproducibility, carrier adhesion to the photoconductor, charge amount during 5-minute sheet running, solid image density, background stains, and fine line reproducibility were evaluated.
0°C, 80% R, H, ) and low humidity (10°C, 30% R1
H,) Environmental conditions were also tested. The results are shown in the following table. 1. It is clear that the carrier according to the present invention is excellent.

Claims (1)

[Claims] A developer carrier consisting of a core with an average particle diameter of 50 μm or more in which magnetic fine particles are dispersed in a binder resin mainly composed of an acrylic copolymer, and an upper layer of a fluorinated alkyl acrylic copolymer covering the core. .