JPH0619199A - Electrophotographic image forming method - Google Patents

Abstract

PURPOSE:To obtain an image forming method without generating the defects of picture quality, such as an after image, even when an image forming device having simple constitution only eliminating a cleaner out of an usual electrophotographic image forming device is used. CONSTITUTION:The electrophotographic image forming method passes through a process uniformly charging a photosensitive body surface, a process forming an electrostatic latent image by irradiating the photosensitive body surface with light corresponding to an image, a process visualizing the electrostatic latent image by a developer and a process transferring the visualized image on a sheet by a transcriber. Further, during repeating the respective processes to form an image without removing the residual developer on the photosensitive body surface, a developer having <=0.25 absorbancy to the light for forming the latent image is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method using a dry developer. More specifically, it is possible to stably obtain a good image by a simple image forming process without a cleaner. And an image forming method for electrophotography.

[0002]

2. Description of the Related Art For a process in which a cleaning section is omitted, a reverse polarity toner of JP-A-63-241584, a two-component toner of JP-A-64-59286, a toner concentration of less than 6%,
In addition, although the hydrophobic silica-containing fine particles of JP-A-2-1870 and the reverse polarity light-transparent fine particles of JP-A-2-118672 have been proposed, when a transfer paper having a low smoothness is used or when the humidity is high,
There is a problem that the transfer efficiency is insufficient, and the potential of the photoconductor cannot be fully attenuated during exposure, resulting in a negative afterimage.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an image forming process having a simple structure in which a cleaner is simply omitted from the conventional electrophotographic image forming method. Accordingly, an object of the present invention is to provide an electrophotographic image forming method capable of stably and quickly obtaining a good image without causing image quality defects such as an afterimage.

[0004]

The structure of the present invention for solving the above-mentioned problems includes a step of uniformly charging the surface of a photoconductor, an electrostatic latent image by irradiating the surface of the photoconductor with light according to an image. After the steps of forming an image, developing this electrostatic latent image with a developer, and transferring this image onto a sheet with a transfer device, the developer remaining on the surface of the photoreceptor is removed. In the electrophotographic image forming method of forming an image by repeating each of the steps without using the above, an electrophotographic image forming method using a developer having an absorbance of 0.25 or less for light for forming a latent image, In the electrophotographic image forming method, the degree of coagulation of the developer is 25% or less, or the absolute value of Q / M of the developing toner on the photoconductor is 5 to 15 μc / g.

The inventors have found that when a developer having an absorbance of 0.25 or less with respect to the light irradiated for forming a latent image is used, the negative residue due to light shielding during exposure is significantly reduced. 780n for image exposure using a semiconductor laser
This means that the absorbance at m is 0.25 or less. Here, the absorbance was measured by preparing a 0.05 wt% THF solution, using a cell having an optical path length of 10 mm, and measuring with a Shimadzu spectrophotometer UV-3100.

The toner used in the present invention can be manufactured by a usual kneading and pulverizing method, by removing a colorant and then kneading and pulverizing, or by dyeing colorless particles obtained by a polymerization method.

The charge control agent used in the present invention includes:
Examples thereof include quaternary ammonium salts, metal-containing azo dyes, salicylic acid complex compounds, and phenol compounds.

As the binder resin used in the present invention, all the binder resins used so far as the binder resin for toner can be applied. Specific examples thereof include homopolymers of styrene such as polystyrene, polychlorostyrene, and polyvinyltoluene and their substitution products; styrene-Pchlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene. -Vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid Styrene-based copolymers such as ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate,
Polyethylene, polypropylene, polyester, polyvinyl butyl butyral, polyacrylic acid resin, rosin,
Examples include modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. These may be used alone or in admixture of two or more. May be used.

As the pigment and dye used in the present invention, all of the conventionally used pigments, dyes and polarity control agents can be applied. Specific examples include ultramarine, aniline blue, chalco oil blue, dipon oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green, rhodamine 6C lake, quinacridone, benzidine yellow, malachide green, hansa yellow G, malachide. Examples include green hexalate, oil black, azo oil black, rose bengal, monoazo dyes and pigments, disazo dyes and pigments, trisazo dyes and pigments, and mixtures thereof.

As the release agent, in addition to synthetic waxes such as low molecular weight polyethylene and polypropylene, candelilla wax, carnauba wax, rice wax,
Wax wax, plant wax such as jojoba oil, beeswax,
Examples thereof include animal waxes such as lanolin and spermaceti, mineral waxes such as montan wax and ozokerite, and oil-based waxes such as hydrogenated castor oil, hydroxystearic acid, fatty acid amide, and phenol fatty acid ester. In addition to the above components, the toner of the present invention contains various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.), resistance, etc. for the purpose of adjusting the thermal properties, electrical properties, physical properties, etc. of the toner as necessary. It is also possible to add auxiliary agents such as regulators (tin oxide, lead oxide, antimony oxide, etc.).

As a method for obtaining colorless resin particles suitable for the present invention, a dispersion polymerization method is preferable, and a dispersion polymerization method disclosed in US Pat. No. 4,885,350 is particularly preferable. As the resin used in the present invention, various thermoplastic resins conventionally known in this type of field can be used. Specific examples thereof include, for example, styrenes such as styrene and parachlorostyrene; vinylnaphthalene; for example, vinyl chloride, vinyl bromide, vinyl fluoride,
Vinyl acetate, vinyl propionate, vinyl benzoate,
Vinyl esters such as vinyl butyrate; for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloro-ethyl acrylate, phenyl acrylate, α Esters of α-methylene aliphatic monocarboxylic acids such as methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate;
Acrylonitrile; methacrylonitrile acrylamide; vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone; for example N-vinyl pyrrole, N
-A polymer obtained by polymerizing a monomer such as an N-vinyl compound such as vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone, or a copolymer obtained by copolymerizing two or more of these monomers in combination. Or a mixture thereof, or a non-vinyl thermoplastic resin such as a rosin-modified phenol formalin resin, an oil-modified epoxy resin, a polyurethane resin, a cellulose resin or a polyether resin, or a mixture thereof with a vinyl resin as described above. be able to. Further, as the resin for obtaining the pressure fixing toner suitable for the pressure fixing method, the following resins can be mentioned. Polyolefin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide, polytetrafluoroethylene, etc.), epoxy resin, polyester resin, styrene-butadiene copolymer, olefin copolymer, (ethylene-acrylic acid copolymer, ethylene- Methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ionomer resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid Examples thereof include a modified phenol resin and a phenol modified terpene resin, and a styrene polymer and a styrene-acrylic copolymer are preferable.

As the dye used for dyeing, the solubility ratio [D] / [D] of the dye to the resin constituting the resin particles is 0. 5
Must be: Further, [D] / [D] is preferably 0.2 or less. The dye is not particularly limited as long as it satisfies the above-mentioned solubility characteristics, but a water-soluble dye such as a cationic dye and an anionic dye may have a large environmental change, and the resistance of the toner becomes low, and the transfer rate deteriorates. Therefore, it is preferable to use vat dyes, disperse dyes, and oil-soluble dyes, and oil-soluble dyes are particularly preferable.

It is also possible to use several kinds of dyes together depending on the desired color tone. The ratio (weight) of the dye to be dyed and the resin particles is arbitrarily selected according to the degree of coloring, but it is usually used in a ratio of 1 to 50 parts by weight of dye with respect to 100 parts by weight of resin particles. Is preferred. For example, if the dyeing solvent is S
When alcohols such as methanol and ethanol having a high P value are used and a styrene-acrylic resin having an SP value of about 9 is used as the resin particles, examples of dyes that can be used include the following dyes. To be

C. I. SOLVENT YELLOW
(6, 9, 17, 31, 35, 100, 102, 10
3,105) C.I. I. SOLVENT orange (2,7,1
3, 14, 66) C.I. I. SOLVENT RED (5,16,17,1
8, 19, 22, 23, 143, 145, 146, 14
9, 150, 151, 157, 158) C.I. I. SOLVENT VIOLET (31, 32,
33, 37) C.I. I. SOLVENT BLUE (22, 63, 7
8, 83-86, 91, 94, 95, 104) C.I. I. SOLVENT GREEN (24, 25) C.I. I. SOLVENT BROWN (3,9) etc.

Among commercially available dyes, for example, Aizen SOT dyes Yellow-1,3,4, Orange by Hodogaya Chemical Co., Ltd.
e-1, 2, 3, Scarlet-1, Red-1,
2,3, Brown-2, Blue-1,2, Viol
et-1, Green-1, 2, 3, Black-1,
4,6,8 and BASF sudan dye, Yellow
w-140, 150, Orange-220, Red-
290, 380, 460, Blue-670 and Mitsubishi Kasei's dialresin, Yellow-3G, F, H2G,
HG, HC, HL, Orange-HS, G, Red-
GG, S, HS, A, K, H5B, Violet-D,
Blue-J, G, N, K, P, H3G, 4G, Gre
en-C, Brown-A and oil colors of Orient Chemical Co., Yellow-3G, GG-S, # 10.
5, Orange-PS, PR, # 201, Scarl
et- # 308, Red-5B, Brown-GR, #
416, Green-BG, # 502, Blue-BO
S, IIN, Black-HBB, # 803, EE, E
X, Sumiplast from Sumitomo Chemical Co., Ltd., Blue GP, OR
Red FB, 3B, Yellow FL7G, GC, Nippon Kayaku's Kayaron, Polyester Black EX-SH30
0, Kayaset Red-B Blue A-2R and the like can be used. Of course, the dye is not limited to the above examples because it is appropriately selected depending on the combination of the resin particles and the solvent used for dyeing.

As the organic solvent used for dyeing the resin particles with the dye, those which do not dissolve the resin particles used or those which cause some swelling, specifically, the difference from the solubility parameter [SP value] Is 1.0 or more, preferably 2.0 or more. For example, for styrene-acrylic resin particles, an alcohol type such as methanol, ethanol or n-propanol having a high [SP value] or n-hexane or n-heptane having a low [SP value] is used. Of course, if the difference in [SP value] is too large, the wetting of the resin particles becomes poor, and good dispersion of the resin particles cannot be obtained.
[Value] The difference is preferably 2 to 5.

After dispersing the resin particles in the organic solvent in which the dye is dissolved, it is preferable to stir while maintaining the liquid temperature at a temperature not higher than the glass transition temperature of the resin particles and 20 ° C. lower than the glass transition temperature. As a result, the permeation rate of the dye into the resin particles can be increased, and it is possible to obtain sufficiently colored resin particles in about 30 minutes to 1 hour. The stirring method may be carried out using a commercially available stirrer, such as a homomixer or a magnetic stirrer. Also, a slurry obtained at the end of polymerization by dispersion polymerization,
That is, the dye may be directly added to the dispersion liquid in which the polymerized resin particles are dispersed in the organic solvent, and the mixture may be heated and stirred under the above conditions. If the heating temperature exceeds the glass transition temperature, fusion between resin particles occurs, and if the glass transition temperature exceeds 20
If the temperature is lower than 0 ° C, the coloring speed becomes slow. The method of drying the slurry after dyeing is not particularly limited, but may be air-dried after filtering, or dried under reduced pressure or directly dried under reduced pressure without filtering. In the present invention, the colored particles obtained by filtering and then air-drying or drying under reduced pressure have almost no agglomeration, and can be reproduced without substantially impairing the particle size distribution of the introduced resin particles. For the purpose of improving the triboelectric chargeability of the toner particles, a charge control agent known in the art can be included in the toner particles. In the present invention, charge control is performed together with the dye in the organic solvent in the resin particle dyeing process. By dissolving the agent, the charge control agent remains on the surface portion of the resin particles after removing the organic solvent after dyeing. In this case, since the charge control agent only needs to be present on the surface portion of the particle, it is only necessary that the dye has a severe solubility property required for the dye. Alternatively, as a method of incorporating the charge control agent into the toner particles, the charge control agent may be mechanically driven into the surface of the dried resin particles after dyeing. In this case, the size of the charge control agent particles is 1 μm.
By the following, the resin particles are firmly struck onto the surface of the resin particles to the extent that they are not easily separated during development. The ratio of the charge control agent to the colored resin particles is arbitrarily selected depending on the toner, but is usually 0.1 to 5 relative to 100 parts by weight of the colored resin particles.
0 parts by weight is preferred. If it is less than 0.1 part by weight, the effect of controlling the charging is too small, and if it exceeds 50 parts by weight, the fixing property is adversely affected.

By defining the absorbance, the margin against the negative residual due to the light shielding is remarkably increased, but when the transfer residual toner is remarkably increased, an afterimage is observed. In various environments, in order to prevent the afterimage, it is necessary to secure a transfer rate above a certain level. Here, the factors on the toner side that influence the transfer rate are the toner Q / M on the photoconductor and the fluidity of the toner. The Q / M on the photoreceptor is preferably 5 to 15 μc / g. When the value of Q / M on the photoconductor is larger than 15 μc / g, the transferability deteriorates. On the other hand, when it is less than 5 μc / g, an image with poor sharpness is obtained as a whole and the transferability is deteriorated at high humidity. The Q / M on the photoconductor collects the toner on the photoconductor in the Faraday gauge with air. The measurement was performed using the so-called suction type Faraday gauge method. The cohesion of the developer is preferably 25 or less. The cohesion degree is an index representing the adhesive force between toners, and when the value is large, the adhesive force between toners is large and the transferability deteriorates. The degree of agglomeration was measured using a powder tester (manufactured by Hosokawa Micron Co., Ltd.) with openings of 75 μm and
5 μm and 22 μm sieves are arranged in this order from the top, and 2 g toner is put into the sieve with 75 μm openings, and the amplitude is 1 m.
Vibration was applied for 30 seconds at m, and the toner weight on each screen was measured after the vibration, and the weights of 0.5, 0.3, and 0.1 were applied to the respective weights and added to calculate the percentage.

[0019]

EXAMPLES The present invention will now be described in more detail with reference to examples.

The amounts (parts) of the components described in the examples are parts by weight.

Example 1 Quinacridone 3 parts Phthalocyanine 2 parts Disazo yellow 5 parts Polyester resin 40 parts The mixture having the above composition was kneaded and pulverized with a three-roll mill.

20 parts of the pulverized product Polyester resin 80 parts Low-molecular-weight polypropylene 5 parts Zinc salicylate 4 parts The mixture of the above composition is melt-kneaded, cooled, coarsely pulverized using a hammer mill, and then finely pulverized by an air jet system. Finely ground. The obtained finely pulverized product was classified to have a volume average particle diameter of 10 μm. To 100 parts of the present particles, 0.5 part of hydrophobic silica (H2000 manufactured by Hoechst) was added and mixed to obtain a toner of the present invention. The aggregation degree of the obtained toner was 21%, and the absorbance was 0.1. Q / M on the photoconductor by putting the developer into the experimental machine from which the cleaning part of Ricoh LP1060 is removed.
Was 13 μc / g. While changing the transfer potential, the transfer residual toner was changed, several sheets were printed, and the afterimage was observed. The relationship between the residual toner amount and the surface potential is shown in FIG.

[0023]

[Table 1]

Afterimages did not occur even after continuous printing on 1000 sheets under the environment of 30 ° C. and 90%. Example 2 Paliogen Black 1 part Quinacridone 0.5 part The mixture having the above composition was kneaded and pulverized by a three-roll mill.

15 parts of the above pulverized product Polyester resin 85 parts Low molecular weight polypropylene 5 parts Zinc salicylate 4 parts The mixture of the above composition is melt-kneaded, cooled and then coarsely pulverized using a hammer mill, and then finely pulverized by an air jet system. Finely ground. The obtained finely pulverized product was classified to have a volume average particle diameter of 10 μm. To 100 parts of the present particles, 0.5 part of hydrophobic silica (H2000 manufactured by Hoechst) was added and mixed to obtain a toner of the present invention. The aggregation degree of the obtained toner was measured to be 19%, and the absorbance was measured to be 0.23. Put the developer in the experimental machine from which the cleaning part of Ricoh LP1060 is removed,
When M was measured, it was 12 μc / g. When several sheets were printed and the afterimage was observed, no afterimage was found.

Example 3 Phthalocyanine blue 20 parts Polyester resin 85 parts Low molecular weight polypropylene 5 parts Zinc salicylate 4 parts The mixture of the above composition is melt-kneaded, cooled and coarsely pulverized using a hammer mill, and then finely pulverized by an air jet method. Pulverized with a machine. The obtained finely pulverized product was classified to have a volume average particle diameter of 10 μm. To 100 parts of the present particles, 0.5 part of hydrophobic silica (H2000 manufactured by Hoechst) was added and mixed to obtain a toner of the present invention. The aggregation degree of the obtained toner was measured to be 18%, and the absorbance was measured to be 0.15. Put the developer in the experimental machine from which the cleaning part of Ricoh LP1060 is removed,
When M was measured, it was 13 μc / g. When several sheets were printed and the afterimage was observed, no afterimage was found.

Example 4 320 g of methanol was placed in a 500 cc three-necked flask equipped with a stirring blade and a condenser, and 6.4 g of polyvinylpyrrolidone (average molecular weight 40,000) was added little by little with stirring to completely dissolve it. Let 25.6 g of styrene,
6.4 g of n-butyl methacrylate and 0.2 g of 2.2'-azobisisobutyronitrile were added and completely dissolved. The inside of the flask was purged with dry argon gas while stirring and left for 1 hour. Polymerization was initiated while stirring at a stirring speed of 200 rpm in a constant temperature water bath of 60 ° C. ± 0.1 ° C. After 15 minutes of heating, the liquid started to become cloudy, and it remained a cloudy and stable dispersion even after 20 hours of polymerization. Polymerization rate is 98%
It was confirmed by gas chromatography that ethylbenzene was used as an internal standard. When the obtained dispersion liquid was cooled and centrifuged at 2000 rpm with a centrifuge, the polymer particles were completely settled and the liquid at the top was transparent. Remove the supernatant and add 200 g of new methanol,
Stir for 1 hour. The operations of centrifuging and washing with methanol were repeated, and finally, washing with water and filtration were performed. The product separated by filtration is air-dried for one day and then dried under reduced pressure at 50 ° C for 24 hours, and 95%
White powder of styrene / n-butyl methacrylate copolymer particles was obtained in a yield of. The volume average particle diameter of the obtained particles was 7.0 μm. The Tg of the resin was 65 ° C. After dissolving 0.5 g of each of Oil Red 5B (manufactured by Orient Chemical Co., Ltd.) and Oil Green BG (manufactured by Orient Chemical Co., Ltd.) in 200 cc of methanol, the mixture was filtered, and 24 g of the polymer particles (A) were added to the filtrate to disperse the mixture at 50 ° C. The mixture was heated and stirred for 1 hour. Then, the dispersion liquid was cooled to room temperature, filtered, and dried to obtain colored resin particles. This colored resin particle 1
After stirring 00 parts and 1 part of the charge control agent Spiron Black TRH (manufactured by Hodogaya Chemical Co., Ltd.) for 5 minutes with an Oster blender, the number of revolutions was changed by Hybridization NHS-1 [manufactured by Nara Machinery Co., Ltd.]. Processing was performed at 7,000 rpm for 5 minutes to obtain a toner. The aggregation degree of the obtained toner was measured to be 16%, and the absorbance was measured to be 0.2. The developer was put in an experimental machine from which the cleaning part of Ricoh LP1060 was removed, and the Q / M on the photoreceptor was measured and found to be 10 μc / g. When several sheets were printed and the afterimage was observed, no afterimage was found.

Example 5 In Example 1, 10% of zinc salicylate as a charge control agent was used.
A toner of Example 5 was obtained in the same manner as in Example 1 except that a part of the toner was used. The Q / M of the obtained toner on the photoreceptor was measured and found to be 21.5 μc / g. When several sheets were printed and the afterimage was observed, no afterimage was found. But 3
When 1000 sheets were continuously printed in an environment of 0 ° C. and 90%, an afterimage was generated.

Example 6 A toner of Example 6 was obtained in the same manner as in Example 1 except that 0.15 part of the additive was used. The aggregation degree of the obtained toner was measured and found to be 43%.
When several sheets were printed and the afterimage was observed, no afterimage was found. However, it is 10 continuously under the environment of 30 ° C and 90%.
After printing 00 sheets, an afterimage was generated.

Example 7 A toner of Example 7 was obtained in the same manner as in Example 1 except that 1 part of zinc salicylate as a charge control agent was used. The photoconductor Q / M of the obtained toner was measured and found to be 3.2 μc / g. When several sheets were printed and the afterimage was observed, no afterimage was found. But 30
When 1000 sheets were printed continuously under the environment of ℃ and 90%,
An afterimage has occurred.

Comparative Example 1 Polyester resin 95 parts Low molecular weight polypropylene 5 parts Carbon black 8 parts Zinc salicylate 3 parts A mixture was prepared in the same manner as in Example 1 to obtain a toner. The absorbance of the obtained toner was measured and found to be 2 or more. When the transfer residual toner was changed while changing the transfer potential, several sheets were printed, and the afterimage was observed. The relationship between the residual toner amount and the surface potential is shown in FIG.

[0032]

[Table 2]

[0033]

As described above, according to the present invention,
An apparatus that uses an image forming process with a simple configuration in which a cleaner is simply omitted from the conventional image forming method for electrophotography, and a good image can be stably and quickly obtained without causing image quality defects such as afterimages. it can.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a residual toner amount and a surface potential in Example 1.

FIG. 2 is a graph showing the relationship between the amount of residual toner and the surface potential in Comparative Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kanjiro Kawasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A step of uniformly charging a surface of a photoconductor, a step of irradiating the surface of the photoconductor with light corresponding to an image to form an electrostatic latent image, and the electrostatic latent image is visualized by a developer. Image formation for electrophotography, in which the image forming process is performed by repeating the above steps without removing the developer remaining on the surface of the photoconductor In the method, the absorbance for light for forming a latent image is 0.
An electrophotographic image forming method, which comprises using a developer having a viscosity of 25 or less. 2. The electrophotographic image forming method according to claim 1, wherein the cohesion of the developer is 25% or less. 3. The image forming method for electrophotography according to claim 1, wherein the absolute value of Q / M of the developing toner on the photoconductor is 5 to 15 μc / g.