JPS60186876A - Electrophotographic method - Google Patents

Abstract

PURPOSE:To prevent generation of dropout of an image by visualizing the image by a developer contg. a toner and pulverous powder of an acrylic polymer, etc. having the average grain size smaller than the average grain size of said toner and removing the residual toner on a photosensitive body after transferring the formed toner image. CONSTITUTION:An electrostatic latent image is formed on an org. photosensitive body contg. >=1 kinds of polymers selected from polyester, polycarbonate and acrylic resin as a binder resin. The electrostatic latent image is visualized by using a developer contg. a toner and pulverous powder having the average grain size smaller than the average grain size of said toner and consisting of >=1 kinds of polymers elected from an acrylic polymer, acryl/styrene copolymer, polymer or copolymer of nitrogenous addition polymerizable unsatd. carboxylic acid and polymer or copolymer of addition polymerizable unsatd. carboxylic acid. The formed toner image is transferred onto a transfer member and thereafter the residual toner is removed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to electrophotography.

In conventional electrophotography, a latent image is formed on a photoconductive photoreceptor, which is converted into a visible image by a developer, and if necessary, the developer is transferred to a receiving paper and fixed to create a permanent image. obtain.

One cycle is then completed by mechanically, electrically, and magnetically cleaning the toner remaining on the photoreceptor.

As can be seen from the basic principle of this electrophotographic method, the photoreceptor is made up of various components, such as a charger, developer, transfer paper,
There is an interaction with the cleaning device, and its performance cannot be avoided from being mechanically or chemically modified due to interaction with such components. Conventionally used organic photoreceptors containing polyester, polycarbonate, acrylic resin, etc. as a binder resin are no exception, and depending on the type of developer, the following defects may occur, and the performance has been significantly improved. The performance of the photoreceptor may not be utilized. That is, when a copy is made using a photoreceptor having a low-resistance protective layer, omissions may sometimes occur in the image. This missing image occurs over a relatively large area over the whole or a part of the copy, and the frequency of occurrence is irregular. This phenomenon does not occur in a photoconductor that does not have a low-resistance protective layer, and is therefore considered to be a phenomenon specific to photoconductors that have a low-resistance protective layer. Furthermore, depending on the type of additive added to the toner as a cleaning aid, cleaning may not be sufficient and filming may occur on the photoreceptor. Furthermore, it has been found that some cleaning aids have a negative effect on the charging of the developer, even if they have good cleaning properties. In any case, it has been difficult to make all the steps of the electrophotographic method using such a photoreceptor function satisfactorily.

Purpose of the Invention Therefore, the purpose of the present invention is to use polyester as a binder resin,
In electrophotography, which forms an electrostatic latent image on an organic photoreceptor containing at least one type of polymer selected from polycarbonate and acrylic resin, and goes through the steps of development, transfer, and cleaning, cleaning defects and image omissions do not occur. An object of the present invention is to provide an electrophotographic method using a developer that is significantly more reliable than conventional electrophotographic methods.

Another object of the present invention is to use the above-mentioned photoreceptor to avoid deterioration or deterioration of the photoreceptor, and at the same time, to exhibit properties that are significantly more stable than those of conventional electrophotographic methods, without deterioration or deterioration as a developer. We are here to provide you with an electrophotographic method.

Structure of the Invention In order to achieve the above-mentioned object, the present inventors have conducted repeated research and developed an electrostatic latent image on an organic photoreceptor containing at least one polymer selected from polyester, polycarbonate, and acrylic resin as a binder resin. This electrostatic latent image is formed by combining the toner with an acrylic polymer, an acrylic/styrene copolymer, or a nitrogen-containing addition polymerizable monomer, which has an average particle size smaller than the average particle size of the toner. A toner visualized and formed using a developer containing fine powder of at least one type of polymer selected from a polymer or copolymer, and a polymer or copolymer of an addition-polymerizable unsaturated carboxylic acid. The inventors have now completed the present invention by discovering that an electrophotographic method characterized by removing toner remaining on a photoreceptor after transferring an image to a transfer member can give significantly better results.

The organic photoreceptor used in the electrophotographic method of the present invention has an organic photoreceptor layer on a conductive substrate.

The organic photosensitive layer has an organic photoconductive material dispersed in a binder resin, and may be a single layer or a laminated layer (for example, a charge generation layer and a charge transport layer). 1
It is also possible to use two or more types (for example, a charge-generating material and a charge-transporting material). As the binder resin, polycarbonate, polyester, and acrylic resin are used, but mixtures thereof or mixtures with other resins may also be used, and furthermore, this binder resin may be partially modified.

Examples of the polycarbonate include those synthesized by an alkali condensation reaction between a polyhydric alcohol and phosgene, or a transesterification reaction between a polyhydric flucol and a low-molecular carbonate ester, and bisphenol A type polycarbonate is preferably used.

Examples of polyesters include saturated polyesters produced by polycondensation of polyhydric alcohols and polybasic acids; polyhydric alcohols include bisphenols; polybasic acids include dicarboxylic acids such as terephthalic acid, aromatic carboxylic acids, etc. .

Examples of acrylic resins include polymers of acrylic acid and methacrylic acid such as polymethyl acrylate, polymethyl acrylate, polymethyl methacrylate, and polybutyl methacrylate, and esters or acrylonitrile of these acids. , or a copolymer.

Organic photoconductive materials include azo pigments such as bisazo pigments and trisazo pigments, charge-generating materials such as benzopy, lylium salt pigments, perylene pigments, phthalocyanine pigments, and squareium pigments, or pyrazoline, aromatic amines, hydrazone, Examples include charge transport materials such as oxadiazole. Further, when an organic photosensitive layer is used on the surface side of the photoreceptor, the photosensitive layer on the substrate side may be an inorganic photosensitive layer.

The fine powder smaller than the average particle size of the toner used in the developer of the present invention is an acrylic polymer, an acrylic/styrene copolymer, a polymer or copolymer of a nitrogen-containing addition polymerizable monomer, and a polymer. This polymer is one type of polymer selected from polymers and copolymers of unsaturated carboxylic acids. Specific examples of monomers constituting this polymer include the following compounds.

That is, examples thereof 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 alcohol include alkyl alcohols such as methyl alcohol, ethyl alcohol, flobyl alcohol, methyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, F-decyl alcohol, tetradecyl alcohol, and hexadecyl alcohol. Alcohol; these alkyl alcohols are partially halogenated; alkoxyalkyl alcohols such as methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, and ethoxypropyl alcohol; henzyl alcohol, phenyl Ethyl alcohol,
@7ralkyl alcohols such as phenylpropyl alcohol and /'; 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 heptamers. 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, octyl styrene, halogenated styrenes such as fluorostyrene, chlorostyrene, fluorostyrene, Schiff's styrene, and iodostyrene; Examples include styrene, acetylstyrene, methoxystyrene, and the like.

Additionally, addition-polymerizable unsaturated carboxylic acids, such as α-ethyl acrylic acid, crotonic acid, α-methylcrotonic acid, α-
Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as ethyl crotonic acid, isocrosinic acid, tiglic acid, and ungellic acid, or addition-polymerizable unsaturated aliphatic monocarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, and dihydromuconic acid. and unsaturated aliphatic dicarboxylic acids.

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.

Other examples include esters of the addition-polymerizable unsaturated carboxylic acids and the alkyl alcohols, halogenated alkyl alcohols, aralkyl alcohols, alkenylal:r-alkyl alcohols, and the like.

Also, a-, mido-, and nitriles derived from the addition-polymerizable unsaturated carboxylic acids; aliphatic monoolenic compounds such as ethylene, propylene, butene, and isozotylene; 1,3-
7'tadiene, 1,3-pentadiene, 2-methyl-1
,3-tutadiene, 2,3-dimethyl-1,3-/'tadiene, 2,4-hexadiene, 3-methy/l/-2,
Examples include conjugated diene aliphatic diolefins such as 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-vinyldihyto90pyridine, N-vinylpyrrole, 2-vinylvirol, N-vinylpyroline, N-vinylpyrrolidine, 2
-vinylpyrrolidine, N-vinyl-2-pyrrolidone, N
Examples include nitrogen-containing vinyl compounds such as -vinyl/L/-2-pyRridone and N-vinylcarbazole.

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 one that has been polymerized using various polymerization methods. That is, not only polymers and bodies 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 such as a fine powder obtained by a method such as a mechanical crushing method can be used.

A spherical one is best.

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 of powder, 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 0.1 to 2 μm, more preferably 0.1 to 2 μm, gives good results.

The amount of fine powder added according to the present invention is from 0.01 to toner.
It can be used at 10% by weight, but more preferably 0
．． 05-2.0% by weight gives good results.

In the electrophotographic method of the present invention, the developer is a mixture of a known toner in addition to the above-mentioned polymer fine powder additive,
Binder resins used in this toner include styrene,
Styrenes such as chlorostyrene and vinylstyrene; Monoolefins such as ethylene, flopylene, butylene, and instyrene; Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; methyl acrylate, ethyl acrylate, and acrylic Esters of α-methylene aliphatic monocarboxylic acids such as butyl acid, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl butyl ether, vinyl ethyl ether, Examples include vinyl ethers such as vinyl butyl ether; monopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isozolobenyl ketone;
Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-maleic anhydride copolymer. Mention may be made of polymers, polyethylene and polypropylene.

Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, and waxes.

In addition, toner coloring agents include carbon black, nigrosine dye, aniline blue, calmile blue, chrome yellow, ultramarine blue, DuPont Oilet 8, quinoline yellow, methylene blue chloride,
Typical examples include phthalocyanine sulfate, malachite green oxalate, lamp plaque, and rose bengal.

The binder resin and colorant are not limited to those exemplified above.

Furthermore, a magnetic toner containing a magnetic material can also be used.

The toner is smaller than about 30 μm, preferably between 3 and 3 μm.
Those having an average particle size of 20 μm can be used.

The developer according to the present invention mixed with the above-mentioned additives may be a so-called two-component developer having a carrier and a toner, or a so-called one-component developer not using a carrier.

When the developer to which the fine powder according to the method of the present invention is added is a two-component developer, carriers that can be mixed with the developer include those whose average particle size is approximately the same as that of the toner, or whose average particle size is approximately the same as that of the toner. The particles are up to 500 μm in size, and various known particles such as iron, nickel, cobalt, iron oxide, ferrite, glass beads, granular silicon, and magnetic powder-dispersed resin particles are used. In addition, the surface of these particles is coated with fluororesin,
It may be coated with a coating material such as acrylic resin or silicone resin.

In the electrophotographic method of the present invention using the above-mentioned photoreceptor and developer, first, the organic photoreceptor using the above-mentioned binder resin is charged,
An electrostatic m-image is formed by the so-called Carlson process of imagewise exposure, and then development is performed. In this case, a developer containing the above-mentioned toner and additives as essential components is used without or with a carrier.

Development is performed by a known method such as a cascade method, a magnetic brush method, or a touchdown method. The toner image formed by development is then transferred and temporarily adhered to a transfer material such as paper to obtain a copy, and the photoreceptor is cleaned of residual toner on the surface and prepared for reuse. This cleaning is performed by various methods such as a blade method, a web method, a push method, and a roll method.

Effects of the Invention The electrophotographic method of the present invention has various excellent effects. That is, when an image was formed using an organic photoreceptor made of a binder resin as in the previous example, image loss occurred, but this does not occur in the present invention. In other words, when an image is formed using the above-mentioned binder resin organic photoreceptor, image dropouts will occur from around the 10,000th print, and once this image dropout occurs, the same phenomenon will occur even if surface polishing etc. However, with the method of the present invention, this phenomenon does not occur even if 100,000 copies are made.

Furthermore, phenomena such as poor cleaning or toner filming do not occur.

Further, the additives used in the present invention have the effect of reducing the deterioration in charging performance compared to the case where no additive is added, without adversely affecting the charging performance.

The present invention will be explained below with reference to Examples and Comparative Examples.
The present invention is not limited in any way by these examples. In addition, in the following items, parts represent parts by weight.

Example 1 Styrene-methyl methacrylate-butyl acrylate copolymer (weight ratio 40/20/40) 90 parts nigrosine dye 2 parts carbon black 1 part was mixed in a Banbury mixer, pulverized, and classified. , a toner with a particle size of 12 microns was obtained. This toner 100
1 part of styrene-methyl methacrylate copolymer fine powder (weight ratio 50150, particle size 0.5 microns) obtained by soap-free emulsion polymerization was added to each part and mixed in a Henschel mixer. In addition, 3 parts of this toner and N
t-Z n ferrite powder (120 microns) 100
A developer according to the present invention was obtained by mixing the following parts.

Comparative Example 1 A control developer was obtained in exactly the same manner as in Example 1 except that copper stearate was used as the fine powder.

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

A modified FX that uses a photoreceptor in which a charge generation layer containing a bisazo pigment and a charge transport layer containing a polycarbonate dispersed on an aluminum substrate are successively laminated on an aluminum substrate, and is equipped with a plan cleaning device. 2 for the developers of Example 1 and Comparative Examples 1 and 2 using a -1075 machine.
A real root running test was conducted with up to 10,000 leaves. The results are shown in the table. The table demonstrates that the electrophotographic method of the present invention is significantly superior.

Note 1) The number of copies that can reproduce a document with an image density of 0.7 with an image density of 0.7 or higher and a fog density of 0.02 or lower.

Claims (1)

[Claims] An electrostatic latent image is formed on an organic photoreceptor containing at least one type of polymer selected from polyester, polycarbonate, and acrylic resin as a binder resin, and this electrostatic latent image is formed using a toner and an average particle size of this toner. From acrylic polymers, acrylic/styrene copolymers, nitrogen-containing addition-polymerizable monomers or copolymers, and addition-polymerizable unsaturated carboxylic acid polymers or copolymers that have a small average particle size. The toner image remaining on the photoreceptor is removed after the toner image is visualized using a developer containing fine powder of at least one selected polymer and transferred to a transfer member. electrophotography.