JP2000284539A - Electrostatic charge image developing toner and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination in an organic photoreceptor by a toner even at high temperatures and to obtain a good image by allowing a specified amount of a styrene oligomer to be contained in the toner comprising a binder resin component and a colorant. SOLUTION: A styrene oligomer is contained by <=100 ppm, preferably 90-0.1 ppm in a toner comprising a binder resin component and a colorant. In this range, the toner does not cause contamination in an organic photoreceptor and exhibits flexibility because the low molecular material is included moderately and resistance to film scraping is enhanced. The content of the styrene oligomer is more preferably 60-1 ppm, particularly preferably 50-5 ppm, most preferably 30-10 ppm. In these ranges, the styrene oligomer penetrates into the resin of an organic photoreceptor film in the molecular state, flexibility is exhibited by plasticization and resistance to film scraping is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner for developing an electrostatic latent image formed on an organic photoreceptor and an image forming method.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors have been put to practical use mainly for inorganic photoconductive materials such as selenium, zinc oxide, cadmium sulfide, and various selenium alloys. Organic electrophotographic photoreceptor (OP) using high quality, environmentally friendly organic photoconductive material at the time of disposal
C) has been put to practical use and is currently the mainstream. However, as compared with the inorganic photoconductor, the problem of the melting of the OPC photoconductor is that the charge transport layer is made of an organic polymer-based resin, and is subject to various environmental changes in a copying machine. is there. One of the major factors is environmental fluctuation such as acid gas such as ozone and NOx generated from the main charger or the transfer charger. Exposure to acid gas causes the charge transport material CT on the surface of the charge transport layer CTL
M and the binder are decomposed, and image blur occurs.
In addition, depending on the type of the CGM, the charge is greatly reduced by the acidic gas, and as a result, the potential contrast is reduced and the background is stained. One of the more significant factors is OPC contamination due to a developer electrostatically adhering on the sleeve of the developing unit or a small amount of toner remaining on the photoreceptor after cleaning. When the OPC photoconductor is in contact with a developer electrostatically attached on the sleeve of the developing unit at a high temperature or a small amount of toner remaining on the photoconductor after cleaning for a long time, OPC
PC contamination occurs, the residual potential increases linearly, and image quality degradation such as background contamination, image blur, and image deletion occurs. The elucidation of this problem is becoming more and more important as the life of the OPC photoconductor is extended.

Japanese Patent Publication No. Hei 8-27552 discloses a styrene copolymer (B) containing 0.01 to 1% by weight of a styrene copolymer oligomer (A) having a number average molecular weight of 1,000 or less. An electrophotographic toner composition is disclosed in which the content of the styrenic copolymer oligomer is changed from 100 ppm to 10,000 ppm.
Has a problem that it is caused by repeating the development and transfer process for a long period of time. In particular, the residual potential rises sharply, and background stains and image blur are likely to occur. This is presumably because such substances enter the photoreceptor and trap the charge to hinder the movement of the charge, so that it is impossible to prevent the occurrence of image defects.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to form an electrostatic latent image on an organic photoreceptor and visualize the latent image using a toner comprising at least a binder resin component and a colorant. OPC under high temperature
Toner that prevents image defects due to contamination of OPC by toner in developer under conditions where photoreceptor and developer are in contact for a long time, and provides a long-term stable image, and image forming method And a resin for toner.

[0005]

Means for Solving the Problems The present inventor forms an electrostatic latent image on an organic photoreceptor, and comprises at least a binder resin component,
In an image forming method for visualizing the latent image by using a toner composed of a colorant, the OPC by the toner in the developer is performed even when the OPC photoconductor and the developer are in contact for a long time at a high temperature. As a result of studying what is necessary as a characteristic of the toner in order to prevent the occurrence of contamination, by limiting the binder resin of the toner in the developer, the OP is improved.
It has been found that it is possible to provide a toner for the above purpose, which eliminates the source of C contamination and is free from OPC contamination.

That is, the present invention comprises the following constitutions (1) to (5). (1) A toner comprising at least a binder resin component and a coloring agent, wherein a styrene oligomer is 100 p
pm or less.

(2) A binder resin used for a toner for developing an electrostatic image, wherein a styrene oligomer is 100 pp
m or less, a resin for styrene acrylic toner.

(3) forming an electrostatic latent image on the organic photoreceptor,
An image forming method for visualizing the latent image using a toner comprising at least a binder resin component and a colorant, wherein the toner described in (1) above is used as the toner.

(4) A voltage is externally applied to the charging member by bringing the charging member into contact with the member to be charged to form an electrostatic latent image on the organic photoreceptor, and comprises at least a binder resin component and a colorant. An image forming method for visualizing the latent image using a toner, wherein a toner containing 100 ppm or less of a styrene oligomer is used as the toner.

(5) The electrostatic latent image on the organic photoconductor is developed with a developer, and the developed image is electrostatically transferred to a transfer material through a transfer step in which the organic photoconductor and the transfer device are in contact with each other. An image forming method, wherein the toner in the developer contains a styrene oligomer of 100 ppm or less.

Hereinafter, the present invention will be described in more detail. In an image forming method for forming an electrostatic latent image on an organic photoreceptor and visualizing the latent image using a toner composed of at least a binder resin component and a colorant, the image forming method is performed under a high temperature.
The following new fact was found as a result of analyzing the mechanism of OPC contamination caused by toner in the developer under the situation where the C photoconductor and the developer were in contact for a long time. Here, high temperature refers to a temperature environment of 30 to 50 ° C.

The basic layer structure of the OPC photoreceptor comprises a conductive support, a charge generation layer CGL and a charge transport layer CTL. In CGL, light is absorbed by the charge generation material CGM, and charge carriers of both positive and negative polarities are generated.

One of the carriers is injected into the CTL and the other is injected into the conductive support by an electric field applied to the photosensitive layer. The carriers injected into the CTL move to the CTL surface by the electric field in the CTL and erase the charge on the photoconductor surface. In order for the photoreceptor to exhibit a photoconductive function, it is necessary that charges are efficiently generated by light absorption, and the charges are transported quickly in the photosensitive layer without holes being trapped on the way. However, when the toner and the OPC come into contact with each other at a high temperature, the adhesiveness is good.
It has been found that PC contamination occurs and holes in the CTL are trapped, so that the surface charge does not disappear and a residual potential remains. Further, it has been found that a styrene oligomer has the greatest effect on a material having a double bond π electron donating system contained in the toner. This is thought to be because the bond between carbons is a double bond every other carbon in the molecular structure of the styrene oligomer, so that it has the strongest electron donating property, and therefore holes are easily trapped.

The styrene oligomer in the present invention refers to a dimer to a 20-mer of styrene, and does not include a styrene monomer. Styrene monomer has a low boiling point,
If left at a high temperature of 0 to 50 ° C. for a long time, it will not volatilize and remain, so it is considered that it does not substantially affect OPC contamination. In the case of the oligomer, it does not volatilize in the temperature range of 30 to 50 ° C., and the organic materials have high affinity with OPC, so that it is considered to cause OPC contamination. Therefore, the smaller the amount of styrene oligomer in the toner, the better. However, if it is 100 ppm or less, there is no influence of OPC contamination by the toner.

The amount of the styrene oligomer is 100 p
pm or less, preferably 90 ppm to 0.1 pp
By setting m in this range, OPC contamination is not caused, and the presence of a moderately low-molecular substance expresses flexibility and improves durability against film abrasion. More preferably 60 ppm to 1 ppm, particularly preferably 50 ppm
-5 ppm, most preferably 30-10 ppm
It is.

In particular, when the styrene oligomer is contained in the above range, a low-molecular substance such as a styrene oligomer enters the resin of the OPC film in a molecular state, and exhibits plasticity by plasticizing, thereby reducing film shaving. The durability is improved.

Further, the binder resin used in the toner of the present invention contains 100 pp of styrene oligomer as a whole resin.
m or less, the styrene oligomer amount is 1
A toner of not more than 00 ppm can be obtained. In addition, the use of a charging roller in the charging step can lower the voltage and prevent the generation of ozone.
Pollution can be prevented.

In order to make the content of the styrene oligomer 100 ppm, the reaction time in the polymerization reaction is lengthened,
The reaction is preferably carried out at a high temperature, but in view of economy, the suspension polymerization is carried out in 70 to 10 hours in 5 to 20 hours.
It is preferably performed at 0 ° C.

The amount can also be adjusted by controlling the kneading temperature in the toner production process, and the styrene oligomer content can be adjusted to 100 ppm by kneading at a high temperature. Further, when the kneading temperature is 100 to 200 ° C., the dispersibility of the toner composition is improved.

An example of the present invention will be described more specifically using a screen. This image forming method is carried out as follows. FIG. 1 is a sectional view of an image forming apparatus in which the image forming method of the present invention is performed. Around the drum-shaped image carrier (1), a charging roller (2), a laser optical system (3), a developing roller (4), a transfer roller (5), a separation charger (6), a charger before cleaning (7), A cleaning roller (8) and a static elimination lamp (9) are provided, and an image is formed by the following operation. A series of processes of image formation will be described as a negative-positive process.

The image carrier (1), which is a photoconductor (OPC) having an organic photoconductive layer, is neutralized by a neutralization lamp (9) and is uniformly negatively charged by a charging roller (2) (for example, -70).
0V), and a latent image is formed (the exposed portion potential is about -100 V) by the laser light irradiated from the laser optical system (3).

The laser beam is emitted from a semiconductor laser and scans the surface of the image carrier (1) in the direction of the rotation axis of the image carrier (1) by a hexagonal prism (polygon) rotating at a high speed. The latent image thus formed is developed by the magnetic brush of the developing roller (4) (the applied voltage is, for example,-
550 V) to form a toner image.

On the other hand, a transfer paper (transfer material) (10) is fed from a paper feed mechanism (not shown), and is synchronized with the leading edge of the image by a pair of upper and lower registration rollers (not shown). The toner image is fed between (1) and the transfer roller (5), and the toner image is transferred. At this time, the transfer bias applied to the transfer roller (5) is, for example, about + 950V. Thereafter, the transfer paper (10) is separated from the image carrier (1), and is discharged as a copy via a fixing device (11).

A method for quantifying a styrene oligomer in the present invention will be described. This quantitative determination is performed by gas chromatography mass spectrometry (GC1MS method) using QP-5000 manufactured by Shimadzu Corporation. The measurement conditions are as follows.

<Measurement conditions> Ion source: EI 70 eV Detector: Cylindrical quadrupole off-axis 2 with brirod
Secondary electron multiplier Mass range: M / Z 29 to 700 Column: DB-5 L = 30 m D = 0.25mm Film = 0.2
5 μm Column temperature: 50 ° C. (hold = 1 min) to 300 ° C.
10 ° C./min temperature rise Vaporization chamber temperature: 350 ° C. Column pressure: He 100 (hold = 1 min) to 1
50 2kPa / min boost

The form of the organic photoreceptor in the present invention will be described below. Examples of the conductive substrate include metals such as aluminum and stainless steel; aluminum alloys and indium oxide.
Tin oxide alloy; plastic having a coating layer of the metal or the alloy; paper or plastic impregnated with conductive particles; cylindrical cylinders and films formed of plastic having a conductive polymer.

On these conductive substrates, the adhesion of the photosensitive layer is improved, the coating properties are improved, the substrate is protected, defects on the substrate are covered,
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate, keeping the photosensitive layer against electrical breakdown, and the like. The undercoat layer is polyvinyl alcohol, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue,
It is formed of a material such as gelatin, polyurethane, and aluminum oxide. The film thickness is usually 0.1 to 10 μm, preferably 0.1 to 3 μm.

The charge generation layer is made of an organic substance such as an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt, and a triphenylmethane dye; A charge-generating substance made of an inorganic substance such as selenium or amorphous silicon is dispersed in a suitable binder, and is formed by coating or vapor deposition. As the binder, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacryl resin, phenol resin, silicone resin, epoxy resin,
And vinyl acetate resin. The amount of the binder agent contained in the charge generation layer is 80% by weight or less, preferably 0 to 40%.
Used by weight. The thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.05 to 2 μm.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting substance in a solvent together with a binder resin if necessary, and applying the solution. The film thickness is generally 5 to 40 μm. As the charge transport material, biphenylene,
Polycyclic aromatic compounds having a structure such as anthracene, pyrene and phenanthrene; nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole and pyrazoline;
Hydrazone compounds; styryl compounds; selenium, selenium-
Examples include inorganic compounds such as tellurium, amorphous silicon, and cadmium sulfide.

As the binder resin for dispersing these charge transport materials, polycarbonate resin, polyester resin,
Resins such as polymethacrylate, polystyrene resin, acrylic resin, and polyamide resin; and organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

As a surface layer, a trapping layer may be provided. Examples of the resin for the protective layer include polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, and a mixture of these resins and a curing agent. These are used alone or in combination of two or more.

As the styrene-based binder resin used in the toner obtained by the present invention, all known resins can be used. For example, polystyrene, poly-p-styrene, a homopolymer of styrene such as polyvinyl toluene and a substituted product thereof, a styrene-p-chlorostyrene copolymer, a styrene-propylene copolymer, a styrene-vinyltoluene copolymer, and a styrene- Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer,
Styrene-butyl methacrylate copolymer, styrene-
α-chloromethyl methacrylate copolymer, styrene
Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrene-based copolymers such as copolymers can be used. To further widen the fixing temperature range, it is desirable to blend a polyester resin.

The polyester resin used as a binder in the present invention is obtained by polycondensation of an alcohol component and a carboxylic acid component. Examples of the alcohol component used include ethylene glycol, diethylene glycol, triethylene glycol, and 1,2-propylene. Glycol, 1,3-propylene glycol, 1,4
-Butanediol, neopentyl glycol, 1,4-
Examples thereof include diols such as butenediol, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, and other dihydric alcohol monomers.

Examples of the carboxylic acid component include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid and sebacic acid. , Malonic acid, anhydrides or lower alkyl esters thereof, dimers of linoleic acid, and other divalent organic acid monomers.

The polyester resin used in the present investigation is not limited to the above-mentioned difunctional monomer, but also contains a tri- or higher polycarboxylic acid as a carboxylic acid component by a tri- or higher polyfunctional monomer. It is a polymer containing the acid anhydride. Examples of the trifunctional or higher polyvalent carboxylic acid monomer which is a multifunctional monomer include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1.2,4- Cyclohexanetricarboxylic acid, 2,
5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-
Dicarboxyl-2-methyl-2-methylenecarboxylpropane, tetra (methylenecarboxyl) methane,
Examples thereof include 1,2,7,8-octanetetracarboxylic acid, embolic trimer acid, and acid anhydrides thereof.

The trihydric or higher polyhydric alcohol used in the present invention may be any of those generally known as trihydric or higher polyhydric alcohols. For example, glycerin, 1,
1,1-trimethylolethane, 1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane,
Examples thereof include pentaerythritol, 1,1,2,2-tetramethylolethane, 1,1,3,3-tetramethylolpropane, sorbitol, and polyvinyl alcohol. These are used in one kind or in a mixture of two or more kinds.

The production method for obtaining the polyester of the present invention is not particularly limited, and the esterification reaction can be performed by a known method. The transesterification can be performed by a known method, and in this case, a known transesterification catalyst can be used. Examples include magnesium acetate, zinc acetate, manganese acetate, calcium acetate, tin acetate, lead acetate, titanium tetrabutoxide and the like.

The polycondensation reaction can be carried out by a known method, and in this case, a known polymerization catalyst can be used. Specific examples include antimony trioxide and germanium dioxide.

A coloring agent and / or
Alternatively, the toner for developing an electrostatic image can be prepared by appropriately melting and mixing with a magnetic powder and, if necessary, a charge control agent and other additives.

As the coloring agent, conventionally known coloring agents such as carbon black, iron oxide pigment, phthalocyanine blue, phthalocyanine green, rhodamine 6G cake, and watching red strontium can be used.
The amount of the colorant contained in the toner is appropriately selected and used in the range of 1 to 60% by weight.

Examples of the charge controlling agent include nigrosine dye, fatty acid-resistant modified nigrosine dye, metal-containing nigrosine dye, metal-containing fatty acid displacement nigrosine dye, 3,5-di-tert-
A chromium complex of butylsalicylic acid or the like can be used, and is usually used in the toner in an amount of 0 to 20% by weight.

A wax having a melting point of 70 ° C. to 170 ° C. is used as a release agent. Specific examples of the release agent include:
Examples thereof include carnauba wax, montan wax, sasol wax, paraffin wax, low molecular weight polyethylene, low molecular weight polypropylene, and ethylene-vinyl acetate copolymer. These are added to the toner in the range of 1 to 10% by weight.

As other additives, silica powder, hydrophobic silica powder, polyolefin, paraffin wax, fluorocarbon compound, fatty acid ester, partially saponified aliphatic carbonate, fatty acid metal salt and the like can be used. 0.1 to 5% by weight in the toner.

The toner of the present invention can be used for either a dry one-component developer or a two-component developer. As a magnetic material in the case of a one-component developer, alloys containing ferromagnetic elements such as iron, cobalt, and nickel, including ferrite, magnetite, etc. Alloys that have become ferromagnetic by treatment, such as alloys of the type called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide. it can. The magnetic material is uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.3 to 30 μm. The content of the magnetic particles is 20% in the toner.
It is desirable that the content be from 70 to 70% by weight, preferably from 40 to 70% by weight.

The toner in the two-component developer is composed of a colorant, a binder resin, and a charge control agent as main components, as is generally used.

The toner compositions according to the present invention are made by any of the well-known toner mixing and grinding methods. For example, all the components are mixed in a predetermined amount, mixed and crushed to thoroughly mix all the components, and then the resulting mixture is pulverized. In another known method of forming toner powders, the colorant, resin and solvent are ball milled and the toner formulation mixture is spray dried.

In order to use the toner composition according to the present invention by a cascade developing method, a magnetic brush developing method, an O-shell developing method, or the like, the composition has an average particle size expressed by weight percentage of about 30 μm or less. It is desirable that this average particle size be between about 4-20 μm for optimal results. For use in powder cloud development, particles having a particle size slightly smaller than 1 μm are desirable.

Cascade development, magnetic brush development, C
Coated and uncoated carriers, such as those used in shell development methods, are well known, but the carrier particles are brought into intimate contact with the toner powder such that the toner powder adheres to and surrounds the carrier particles. When
The carrier particles may be formed of any suitable material as long as the toner powder acquires a charge having a polarity opposite to that of the carrier particles. Accordingly, the toner compositions of the present invention can be used in combination with conventional carriers to develop electrostatic latent images on any suitable electrostatic latent image bearing surface, including conventional photoconductive surfaces. Is done.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically by way of examples. The present invention is not limited to these Examples and Comparative Examples. Table 1 shows examples of the synthesis of vinyl resins.

[0050]

[Table 1]

Ion-exchanged water and monomer are charged into a 3 L flask equipped with a cooling tube, a stirrer, a gas introduction tube and a thermometer. Examples of the formulation are shown in Table 1 in Examples A-1 to A-2,
This is described as Comparative Examples B-1 to B-2. The liquid was heated while stirring, and the temperature was raised to a specified reaction temperature to carry out the reaction. The obtained polymer was washed with water and dried at a normal temperature of 10 Torr to obtain a powdery powder having a volatile content of 1% or less.

A: Toner Production Method 100 parts of resin, 5 parts of carnauba wax, 10 parts of carbon black, and 2 parts of a metal complex dye under the conditions shown in Table 1 were melt-kneaded with two rolls. The kneading conditions are shown in Table 2.

B: Method of Making Developer 100 parts of magnetite and 2 parts of the toners of Examples T1 to T4 and Comparative Examples T5 to T8 of Table 2 were mixed by turbuler to prepare a developer.

C: Image Evaluation Method Image evaluation was performed using a developer obtained by modifying the developer obtained in B so that it can be mounted on Ricoh Spirlio 7000.
The charger was a corona discharge type and the applied voltage was 5
KV, a charging roller having an AC voltage of 400 V, a transfer charger having a corona discharge type, an applied voltage of 3 KV, and a transfer roller having a DC voltage of 300 V were used. Further, the roller method is preferable because the damage to the photoconductor is smaller than that of the charger method.

In each case, the following evaluation was performed after printing 100,000 sheets of a standard image having an image ratio of 7%. Image blur is 600dp
The fine line printed at the resolution of i was magnified by a microscope, and the reproducibility was evaluated step by step using 1 to 5 step samples. Image deletion means that the reproducibility of printed characters is 5
This was evaluated using a stage sample of the stage. The background stain is obtained by reading the density of a white solid image printed after running with a Macbeth densitometer.

[0056]

[Table 2]

[0057]

According to the present inventions (1) and (3), even at a high temperature, there is no OPC contamination by toner, and a good image free from image defects can be obtained. By using the resin of the present invention (2), a toner having an amount of styrene oligomer in the toner of 100 ppm or less can be obtained. By mounting the charging step of the present invention (4), OPC contamination can be further prevented, and a good image without image defects can be obtained. By mounting the transfer step of the present invention (5), OPC contamination can be further prevented, and a good image without image defects can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an example of an image forming apparatus embodying the present invention.

[Explanation of symbols]

Reference Signs List 1 OPC photosensitive member 2 Charger (corona charge, charging brush, charging roller, etc.) Charge OPC surface potential to 100 to 1000 V 3 Image reading device (exposed with laser light via polygon mirror) 4 Developing device (magnetic or non-magnetic) One-component or two-component developing device) developing potential of 100 to 800 V 5 transfer device (applied voltage 100 to 10 in case of contact type)
00V, 1-10 KV for corona discharge type) 6 Transfer paper static eliminator 7 Cleaner unit 8 Cleaning brush, roller 9 Static elimination lamp 10 Transfer paper traveling direction Linear velocity 50 to 1000 mm / sec
c11 Fixing roller Set to 100-200 ° C

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Yamashita 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Masato Igarashi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh (72) Inventor Noritaka Kinoshita 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Kosuke Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company

Claims (5)

[Claims] 1. A toner for developing an electrostatic image, comprising at least 100 ppm of a styrene oligomer, comprising a binder resin component and a colorant. 2. A styrene acrylic toner resin, which is a binder resin used for a toner for developing an electrostatic image and contains a styrene oligomer in an amount of 100 ppm or less. 3. An image forming method in which an electrostatic latent image is formed on an organic photoreceptor, and the latent image is visualized using a toner composed of at least a binder resin component and a colorant. An image forming method using the toner according to claim 1. 4. A toner comprising at least a binder resin component and a colorant, wherein a charging member is brought into contact with a member to be charged and a voltage is externally applied to the charging member to form an electrostatic latent image on the organic photoreceptor. Wherein the toner comprises a toner containing 100 ppm or less of styrene oligomer as the toner. 5. An image in which an electrostatic latent image on an organic photoreceptor is developed with a developer, and the developed image is electrostatically transferred to a transfer material via a transfer step in which the organic photoreceptor and the transfer device are in contact with each other. An image forming method, wherein the toner in the developer contains a styrene oligomer in an amount of 100 ppm or less.