JPS60186866A - Developer - Google Patents

Abstract

PURPOSE:To prevent decrease of image density and increase of fog by preparing a developer composed of a ferrite carrier, a toner made of a polyester resin, and a fine powder of a polymer made of acrylic polymers, etc., and having an average particle diameter smaller than that of the toner. CONSTITUTION:A developer is prepared by mixing a ferrite carrier, a toner obtained by dispersing a colorant into a polyester resin, and a fine powder made of at least one kind of polymer selected from acrylic polymers, acrylic/styrene (including styrene derivs.) copolymers, polymers or copolymers of N-contg. monomers capable of addition polymn., and polymers and copolymers of polymerizable unsatd. carboxylic acids, and having an average particle diameter smaller than that of the toner, preferably, 0.05-5mum, still preferably, 0.1- 2.0mum in fine powder of 0.01-10wt%, preferably, 0.05-2.0wt% of the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developer, and particularly to a 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 a charge is imparted to the toner by frictional charging between the toner and the carrier.
A method of visualizing an electrostatic latent image using this toner is known. The visualized toner image on the photoreceptor or electrostatic recording material is transferred to 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 transfer paper. It is cleaned in preparation for the copying process. This residual toner can be cleaned using the blade method.
Various methods such as the brush method and the web method are used, but as the copying process continues thousands or tens of thousands of times, the toner that cannot be removed by these cleaning/gluing methods gradually wears off. It accumulates on the surface of a photoreceptor, etc., resulting in inconveniences such as so-called poor cleaning or toner filming. In order to improve this phenomenon, for example,
No. 1, JP-A No. 51-1130, JP-A-50-12063, JP-A No. 52-8474, etc. propose a method of mixing additives into a developer composition. Namely, Special Public Interest Publication 1978-814
No. 1 uses organic polymers with low surface energy such as polytetrafluoroethylene and polyvinylidene fluoride,
-1130 is a non-adhesive polymer with a triboelectrification series smaller than that of sulfur, and JP-A-50-1206!11 is a non-adhesive polymer with a triboelectrification series smaller than that of sulfur, colloidal silica, etc. In addition, in JP-A No. 52-84741, polystyrene particles are added to the developer, resulting in poor cleaning or toner filming on the surface of the photoreceptor etc. due to a decrease in adhesion ability or a polishing effect. This is to prevent Although these methods are useful to some extent in terms of 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. When the number of copies is 10,000 to 20,000, image density decreases and fog increases, and eventually a phenomenon occurs in which copies cannot be made. This phenomenon occurs particularly in a high temperature and high humidity environment. Since no toner filming phenomenon occurred on the photoreceptor at this time, this phenomenon is considered to be due to a decrease in triboelectric charging ability.

Purpose of the Invention The present invention has been made in view of the above circumstances, and provides a developing device that prevents poor cleaning or toner filming on a photoconductor or electrostatic recording medium, and prevents a decrease in image density and an increase in fog. The purpose is to provide a drug.

Structure of the Invention In order to achieve the above object, the present inventors have conducted extensive research, and have developed a developer containing a carrier, a toner, and a fine powder having an average particle size smaller than the average particle size of the toner. A toner with a colorant dispersed in a polyester resin, and a polymer of an acrylic polymer, an acrylic/styrene copolymer, a polymer or copolymer of a nitrogen-containing addition polymerizable monomer, and an addition polymerizable unsaturated carboxylic acid. The inventors have discovered that the above object can be achieved by a developer characterized by using a fine powder of at least one type of polymer selected from polymers or copolymers, and have completed the present invention.

Fine powder 4 smaller than the average particle size of the toner used in the developer according to the present invention, an acrylic polymer, an acrylic/styrene copolymer, a polymer or copolymer of a nitrogen-containing addition polymerizable monomer, and a polymer It is at least one type of polymer selected from polymers or copolymers of unsaturated carboxylic acids. Specific examples of monomers constituting this polymer include esters of acrylic acid and methacrylic acid with alkyl alcohols such as alkyl alcohols, halogenated alkyl alcohols, alkoxyalkyl alcohols, aralkyl alcohols, and alkenyl alcohols. Specific examples of the above-mentioned alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, phthyl alcohol, amyl alcohol, hexyl alcohol, hexyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetratecyl alcohol, and hexatecyl alcohol. Alkyl alcohol: Some of these alkyl alcohols have been halogenated. Halogenated alkyl alcohol: Methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, ethoxypropyl alcohol, etc. Alkoxyalkyl alcohol; benzyl alcohol, phenylethyl Alcohol, phenylpropyl alcohol, 17 Ralkyl alcohol; alkenyl alcohol, such as allyl alcohol, crotonyl alcohol.

These acrylic monomers may be used as a single polymer, or may be used as a copolymer with other types of monomers. Specific examples of other types of monomers in this case include styrene and its derivatives, such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene,
Alkyl styrenes such as diethyl styrene, triethyl styrene, flobyl styrene, butyl styrene, hexyl styrene, heptyl styrene, octylstyrene, 7
Examples include halogenated styrenes such as Orostyrene, chlorostyrene, bromostyrene, cyphlomostyrene, and iodostyrene, as well as nitrostyrene, acetylstyrene, methoxystyrene, and the like.

In addition, addition-polymerizable unsaturated carboxylic acids, i.e., thi, α-ethyl acrylic acid, chloro/acid, α-methyl crotonic acid, α
- Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as ethyl crotonic acid, isocrot/acid, tiglic acid, ungellic acid, or such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, dihydromuconic acid Examples include addition polymerizable unsaturated aliphatic dicarboxylic acids.

Furthermore, various metal salts of these carboxylic acids can also be used, and the metal salts 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 nitriles derived from the addition polymerizable unsaturated carboxylic acid; ethylene, propylene, butene,
Aliphatic monoolefins such as inbutylene: 1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3
-butadiene, 2,3-dimethyl-1,3-butadiene, 2,4-hexadiene, and 3-methyl-2,4-hexadiene.

Furthermore, vinyl acetates, vinyl ethers; vinylcarbazole, vinylpyridine, vinylpyrrolidone, 2-vinylpyridine/, 4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butenylpyridine, 4 -pentylpyridine, N-vinyl-
Piperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrrole, N-vinylpyrroline, N-vinylpyrrolidine, 2-
Vinylpyrrolidine, N-vinyl-2-pyrrolidine, N
Examples include nitrogen-containing vinyl compounds such as -vinyl-2-piperitone and N-vinylcarbazole.

The fine powder having an average particle diameter smaller than the average particle diameter of the toner powder used in the present invention may be one obtained by polymerization using various polymerization methods. That is, not only polymers formed 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 obtained by granulation or a fine powder obtained by a method such as mechanical pulverization can be used.

A spherical one is best.

This fine powder is mixed into the developer.

That is, the fine powder is first mixed with toner particles or carrier particles, and then this mixture is mixed into the developer, or the fine powder is mixed directly into the 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 is preferably 0.05 to 5 μm.
A particle size of 1 μm, preferably 0.1 to 2 μm, gives good results.

The amount of fine powder added according to the present invention is Q, 01~
It can be used with a weight of 10, but preferably 0
．． 05 to 50 weight class gives good results.

The toner used in the developer according to the present invention consists of a polyester resin and a colorant. Here, the polyester resin is obtained by polycondensation of alcohol and carboxylic acid. Specific examples of alcohol components include ethylene glycol,
Bifunctional alcohol monomers such as diethylene glycol, bisphenol A1, polyoxy7-ethylated bisphenol A, etc. may be mentioned, and if necessary, sorbitol,
Trifunctional or polyhydric alcohol monomers such as trihentaerythritol, trimethylolpropa/etc. can also be used. Specific examples of the carboxylic acid component include aliphatic or aromatic dicarboxylic acids such as maleic acid, 7-malic acid, phthalic acid, isophthalic acid, terephthalic acid, and adipic acid, and 1.2.4- Trifunctional or polyfunctional carboxylic acids such as benzenetricarboxylic acid and 1,2°5-benzenetricarboxylic acid can also be used.

Further, as the colorant, any dye pigment or carbon black can be used.

The carrier used in the developer of the present invention is so-called ferrite powder. That is, it is a single or composite ferrite formed by the general formula MFe204 (M is a divalent metal). Here, M is Ni, Zn, or Ou.

Hail OeL, Co, etc. Ferrite powder can be produced, for example, by the method disclosed in JP-A-50-50996.

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 bisazo pigment, or an electrostatic latent image is formed on a photoreceptor made of 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 terephthalate using a needle electrode, etc., and a developing method such as a magnetic brush method, a cascade method, or a touchdown method is used to form an electrostatic latent image. A toner image is formed by adhering the developer of the present 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 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 present 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, developers using conventionally known additives can perform sufficient cleaning at the initial stage, but gradually the IJ = ing performance deteriorates, and when the number of sheets exceeds 20,000 to 50,000 sheets, the The toner remains in the image, resulting in afterimages or band-like black streaks on the next copy.

Z　Developer life 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, there is almost no decrease in the density of the copied image, even for originals with an image density of 0.7, which is particularly susceptible to this effect. Who? Furthermore, it is not affected by high temperature and high humidity environments.

(5) The photoreceptor is not easily damaged and toner filming does not occur.

EXAMPLES The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the scope of the present invention is not limited by these Examples. In addition, parts in each item represent parts by weight.

Example 1 A polyester resin (consisting of 30 parts of terephthalic acid/20 parts of propylene oxide bisphenol A/10 parts of trimellitic acid) was blended with 90 parts of carbon black and 10 parts of carbon black. After cross-mixing, crushing, and classification using a Banbury kneader, A toner with a particle size of 12 microns was obtained.

To 100 parts of this toner, α5 parts of fine polystyrene powder (particle size α5 microns) obtained by soap-free emulsion polymerization was added and mixed in a Henschel mixer to obtain a toner according to the present invention. Three parts of this toner and 100 parts of Ni--Zn ferrite powder (120 microns) were mixed to obtain a developer according to the present invention.

Example 2 Instead of fine polystyrene powder, fine styrene-isobutyl methacrylate copolymer powder (weight ratio 80/20, particle size 0) was used.
．． A developer according to the present invention was obtained in exactly the same manner as in Example 1, except that a developer (4 microns) was used.

Comparative Example 1 A control developer was obtained in the same manner as in Examples 1 and 2 except that no fine powder was added.

When the developers of Experimental Example 1.2 and Comparative Example 1 were subjected to a collecting machine running test of up to 50,000 sheets using Fuji Xerox's yK4SVO, the following results were obtained, clearly demonstrating the excellent effects of the developer of the present invention. Became.

Claims (1)

[Claims] A developer containing a carrier, a toner, and a fine powder having an average particle size smaller than the average particle size of the toner, a ferrite carrier, a toner in which a colorant is dispersed in a polyester resin, and an acrylic polymer, an acrylic/ Fine powder of at least one type of polymer selected from styrenic copolymers, polymers or copolymers of nitrogen-containing addition polymerizable monomers, and polymers or copolymers of polymerizable unsaturated carboxylic acids. A developer characterized in that it is used.