JPH023174B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a developer, and particularly to an electrophotographic two-component developer that prevents deterioration of developer properties. Prior Art As a developing method applied to electrophotography or electrostatic recording, a developer consisting of toner and carrier is used, and the toner is charged by frictional charging between the toner and carrier, and this toner forms an electrostatic latent image. There are known methods to visualize this. The visualized toner image on the photoreceptor or electrostatic recording material is transferred to a transfer paper and fixed to form a copy, while the residual toner on the photoreceptor or electrostatic recording material that could not be transferred after transfer is transferred to the next step. It is cleaned in preparation for the copying process. To clean this residual toner,
Various cleaning methods are used to clean the photoreceptor, such as the blade method, brush method, and web method, but as the copying process continues thousands or tens of thousands of times, toner that cannot be removed by these cleaning methods gradually builds up on the photoreceptor, etc. It accumulates on the surface, causing problems such as poor cleaning or toner filming. In order to improve this kind of development, for example,
No. 51-1130, Japanese Unexamined Patent Publication No. 120631, 1973, 1972-
No. 84741 and the like propose a method of mixing additives into a developer composition. In other words, JP-B No. 48-8141 uses organic polymers with low surface energy such as polytetrafluoroethylene and polyvinylidene fluoride, and JP-Ko 51-1130 uses non-stick polymers with a triboelectric series smaller than that of sulfur. , JP-A-50-120631 discloses abrasives such as non-stick polymers and colloidal silica whose triboelectrification series is smaller than sulfur, and JP-A-52-120631.
In No. 84741, polystyrene particles are added to each developer to prevent poor cleaning or toner filming on the surface of a photoreceptor etc. due to a reduction in adhesion ability or a polishing effect. Although these methods are somewhat useful in preventing poor cleaning or toner filming, developers mixed with such additives have a lower ability to triboelectrically charge toner than developers without such additives. There is a problem with this. In other words, when the number of copies is 10,000 to 20,000, image density decreases and fog increases, and finally, development occurs that makes it impossible to copy. This development occurs particularly markedly in a high temperature and high humidity environment. At this time, toner film development did not occur on the photoreceptor, so this development is considered to be due to a decrease in triboelectric charging ability. On the other hand, in order to extend the life of the developer, various measures have been proposed and implemented. and styrene copolymers, fluorinated polymers disclosed in JP-A-47-17434, para-xylene polymers disclosed in JP-A-49-84249, JP-A-50
-Resins such as silicone polymers disclosed in No. 2543, including iron powder, ferrite powder, magnetite powder,
A carrier coated with glass beads or the like may be used, and by implementing these measures, the life of the developer can be significantly extended. However, on the other hand, it is also possible to extend the life of the developer by controlling the chargeability of the toner. For example, O, O′- It is a chromium or gobalt complex of dihydroxyazo dye, and is an azine-based black dye disclosed in Japanese Patent Publication No. 1267-1983. A further example of a combination of a coated carrier and a toner containing a charge control agent is a 2:1 type combination of an organosilicon polymer coated carrier and a specific O,O'-dihydroxyazo dye disclosed in JP-A-58-152256. There are toners that contain chromium complex salts. Although this combination certainly makes it possible to stabilize the chargeability and extend the lifespan of the developer, it cannot imitate the above-mentioned drawbacks, that is, the poor cleaning properties, and furthermore, Addition of metal soaps, polyolefin powder, etc. has the disadvantage of adversely affecting charging stability and longevity. Purpose of the Invention The present invention has been made in view of the above circumstances, and aims to prevent poor cleaning or toner filming on a photoconductor or electrostatic recording medium, prevent a decrease in image density and an increase in fog, The purpose of the present invention is to provide an electrophotographic two-component developer with a long life. Structure of the Invention In order to achieve the above object, the inventors of the present invention have conducted repeated research on a carrier whose surface is coated with a silicone resin, a toner powder that is negatively charged due to frictional electrification with the carrier, and an average particle size of this toner powder. and a fine powder having an average particle size smaller than the particle diameter, and the fine powder includes an acrylic acid ester monomer, a methacrylic acid ester monomer, a styrene monomer, a nitrogen-containing addition polymerizable monomer, and a polymerizable unsaturated carboxylic acid. An electrophotographic two-component developer comprising a single or copolymer obtained from one or more monomers selected from monomers and having an average particle size of 0.05 to 5 μm, more preferably, the toner powder is styrene. The present object is achieved by an electrophotographic two-component developer containing a coloring agent and a charge control agent in a system resin, wherein the charge control agent is a chromium complex salt of an O,O'-dihydroxyazo dye. The inventors have discovered that the following can be achieved, and have completed the present invention. The fine powder smaller than the average particle size of the toner used in the developer according to the present invention is selected from acrylic acid ester monomers, methacrylic acid ester monomers, styrene monomers, nitrogen-containing addition polymer monomers, and polymerizable unsaturated carboxylic acid monomers. It consists of a homopolymer or a copolymer obtained from one or more types of monomers. Specific examples of monomers constituting this polymer include esters of acrylic acid and methacrylic acid with alcohols such as alkyl alcohols, halogenated alkyl alcohols, alkoxyalkyl alcohols, aralkyl alcohols, and alkenyl alcohols. Specific examples of the alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amine alcohol, hexyl alcohol,
Alkyl alcohols such as heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, and hexadecyl alcohol; halogenated alkyl alcohols that partially halogenate these alkyl alcohols; methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl Alcohol, 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. These acrylic monomers may be used as a single polymer, or may be copolymerized with other types of monomers. Specific examples of other types of monomers in this case include styrene and its derivatives, such as methylstyrene, dimethylstyrene,
Alkylstyrenes such as trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene, halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene , and further include nitrostyrene, acetylstyrene, methoxystyrene, and the like. Additionally, addition polymerizable unsaturated carboxylic acids, namely 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, or maleic acid,
Examples include addition-polymerizable unsaturated aliphatic dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, and dihydromuconic acid.
Furthermore, various metal salts of these carboxylic acids can also be used, and this metal salt formation can be carried out after the completion of polymerization. Also included are esterification products of the addition-polymerizable unsaturated carboxylic acid and alcohols such as the alkyl alcohols, halogenated alkyl alcohols, aralkyl alcohols, and alkenyl alcohols. Also, amides and nitrites derived from the addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene, and isobutylene; 1,3-butadiene, 1,3-pentadiene, 2-methyl-1, 3-butadiene, 2,
Examples include conjugated diene-based aliphatic diolefins such as 3-dimethyl-1,3-butadiene, 2,4-hexadiene, and 3-methyl-2,4-hexadiene. Furthermore, vinyl acetates, vinyl ethers; vinylcarbazole, vinylpyridine, vinylpyrrolidone, etc., 2-pinylpyridine, 4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butenylpyridine, -Pentylpyridine, N-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrrole, N-vinylpyrrole, N-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl 2-pyrrolidone , N-vinyl-2-piperidone, and N-vinylcarbanol. The fine powder having an average particle size smaller than the average particle size of the toner powder used in the present invention can be obtained by polymerization using various polymerization methods. That is, not only polymers made into particles by emulsion polymerization, soap-free emulsion polymerization, suspension polymerization, etc., but also polymers obtained by each of the above polymerization methods, solution polymerization, bulk polymerization, etc. are dissolved in a solvent and then spray-dried. A fine powder granulated by a method or a fine powder obtained by a method such as mechanical pulverization can be used. The above-mentioned fine powder can be in any shape such as amorphous, spherical, flat, granular, etc., but it is particularly preferable to use a substantially spherical powder. This fine powder is mixed into the developer. That is, this fine powder is first mixed with toner particles or carrier particles, and then this mixture is mixed into a developer, or the fine powder is mixed directly into a developer. The fine powder according to the present invention is not limited to the use of only one type, but a plurality of types can be used in combination. Further, the fine powder according to the present invention can be used in combination with other additives. The average particle size of the fine powder according to the present invention needs to be smaller than the average particle size of the toner powder, but preferably
A particle size of 0.05 to 5 μm, more preferably 0.1 to 2 μm gives good results. The amount of fine powder added according to the present invention is
0.01 to 10% by weight can be used, more preferably 0.05 to 2.0% by weight gives good results. The toner used in the developer of the present invention has a colorant dispersed in a styrene resin, and the styrene resin herein refers to a polymer or copolymer containing a styrene monomer as a main component. . Specific examples of the styrene monomer include the above-mentioned styrene and its derivatives. Specific examples of monomers that can be copolymerized with styrene include the above-mentioned acrylic monomers,
Namely, esterified products of acrylic acid and methacrylic acid; the above-mentioned polymerizable unsaturated carboxylic acids, their esterified products, amides and nitriles thereof; the above-mentioned aliphatic monoolefins; and the above-mentioned conjugated diene-based aliphatic diolefins. Furthermore, vinyl chloride, vinyl bromide, vinyl iodide,
1,2-dichloroethylene, 1,2-dibromoethylene, 1,2-diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride, vinylidene fluoride Examples include halogenated aliphatic olefins such as. The toner can contain various dyes, pigments, and carbon black as colorants. Copper phthalocyanine or its derivatives are also used as charge control agents, but particularly effective are
2:1 type metal complexes of O,O'-dihydroxyazo dyes, especially chromium complexes. This is expressed by the following general formula. In the above formula, X, Y, Z, X', Y', and Z' each represent a hydrogen atom, an alkyl group, an alkoxy group, a nitro group, a halogen atom, a carbonyl group, a hydroxyl group, a sulfone group, a sulfonamide group, etc. express. Furthermore, Z may be an atomic group bonded to a substituted or unsubstituted phenyl group via an amide bond. A represents H, an alkali metal, an aliphatic ammonium, or a pyridinium cation. The carrier used in the developer according to the present invention is obtained by coating a core selected from iron powder, ferrite powder, magnetite powder, glass beads, etc. with silicone resin. Here, as the silicon resin, for example, (1) SiO ₂ , CH ₃ SiC _3/2 ,
A copolymer made by combining the structural units of (CH ₃ ) ₂ SiO and (CH ₃ ) ₃ SiO _1/2 , (2) CH ₃ SiO _3/2 ,
( _CH3 ) _{2SiO , C6H5SiO3 / 2} , ( _C6H5 )( _CH3 )SiO,
It is a copolymer made by combining structural units of (C ₆ H ₅ ) ₂ SiO, and it hardens into a three-dimensional structural polymer. Furthermore, so-called acrylic-modified silicone resins, alkyd-modified silicone resins, and epoxy silicone resins that are modified from such polymers are also included. It can be obtained by spraying a silicone resin dissolved in a carrier solvent onto the core and drying it, but it is preferable to dry at a relatively high temperature or to harden it in an electric furnace after drying. The developer of the present invention can develop an electrostatic latent image formed on a photoreceptor or an electrostatic recording medium. That is, an electrostatic latent image is electrophotographically formed on a photoreceptor made of an inorganic photoconductive material such as selenium, zinc oxide, cadmium sulfide, or amorphous silicon, or an organic photoconductive material such as a phthalocyanine pigment or a bisazo pigment; An electrostatic latent image is formed on an electrostatic recording medium having a dielectric material such as polyethylene terephthalate using a needle-like electrode, and a book is printed on the electrostatic latent image using a developing method such as a magnetic brush method, a cascade method, or a touch-down method. A toner image is formed by adhering the developer of the invention. After this toner image is transferred to a transfer material such as paper, it is fixed and becomes a copy, and the toner remaining on the surface of the photoreceptor etc. is cleaned. As the cleaning method, various methods such as a blade method, a brush method, a web method, and a roll method can be used. Effects of the Invention The effects obtained by the developer of the invention are as follows. 1. Poor cleaning can be prevented. When cleaning the toner remaining on the photoreceptor, etc., the developer containing the fine powder of the present invention will not cause cleaning defects even if 50,000 copies are made. On the other hand, with developers using conventionally known additives, although sufficient cleaning can be achieved initially, the cleaning performance gradually decreases and
If the number of copies exceeds 30,000, toner remains in the form of an image on the photoreceptor, resulting in afterimages or band-like black streaks on the next copy. 2. The life of the developer can be extended. The developing ability of a developer, particularly the triboelectric charging ability, gradually decreases, and this decrease is particularly likely to occur in developers using conventional additives. However, the developer according to the present invention is less likely to cause a decrease in developing ability, and even after 50,000 copies are made, even for originals with an image density of 0.7, which is particularly susceptible to such effects,
There is almost no decrease in the density of the copied image. Furthermore, it is not affected by high temperature and high humidity environments. 3. The photoreceptor is not easily damaged and toner filming does not occur. The present invention will be explained in more detail below using Examples and Comparative Examples, but the scope of the present invention is not limited in any way by the Examples below. In each example, all parts represent parts by weight. Example Styrene-butyl methacrylate copolymer 88 parts O,O'-dihydroxyazo dye chromium complex
By mixing 2 parts with 10 parts of carbon black, a toner with a particle diameter of 12 microns was obtained after kneading, pulverization, and classification.For 100 parts of this toner, methyl methacrylate fine powder obtained by soap-free emulsion polymerization (particle size 0.5 micron) was added and mixed in a Henschel mill to obtain a toner according to the present invention. On the other hand, methylphenylsiloxane was applied to 100 micron iron powder using a solvent in a fluidized bed and dried and hardened to obtain a carrier. 3 parts of toner were sufficiently mixed with 100 parts of this carrier to obtain a developer according to the present invention. Comparative Example A control developer was obtained in the same manner as in the example except that no fine powder was added. Experiment When the developers obtained in the Examples and Comparative Examples were put into a Fuji Xerox copying machine FX4370 and an actual running test was conducted on 100,000 copies, the results shown in the table below were obtained, indicating that the developer of the present invention The effectiveness of the drug has become clear.

[Table] Number of sheets.

Claims (1)

[Claims] 1. A carrier whose surface is coated with silicone resin;
A toner powder that is negatively charged due to frictional charging with the carrier and a fine powder having an average particle size smaller than the average particle size of the toner powder are mixed,
The fine powder is a single or copolymer obtained from one or more monomers selected from acrylic acid ester monomers, methacrylic acid ester monomers, styrene monomers, nitrogen-containing addition polymerizable monomers, and polymerizable unsaturated carboxylic acid monomers. 1. An electrophotographic two-component developer characterized by having an average particle size of 0.05 to 5 μm. 2. The toner powder contains a colorant and a charge control agent in a styrene resin, and the charge control agent contains O,
The electrophotographic two-component developer according to item 1 of the claims, characterized in that it is a chromium complex salt of O'-dihydroxyazo dye.