JP2006268056A - Electrostatic charge image-developing toner and image-forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image-developing toner which has excellent low-temperature fixability, high-temperature offset resistance and anti-blocking property and which enables a toner image and a fixed image of high quality to be formed in various environments. <P>SOLUTION: The electrostatic charge image-developing toner has toner particles containing at least a binder resin, a colorant and a wax. The wax contains a specified ester compound by 50 to 100 wt.% (based on the weight of the wax). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner for developing an electrostatic charge image in an image forming method such as electrophotography and electrostatic printing, and an image forming method using the toner. In particular, the present invention relates to a toner for developing an electrostatic charge image that is used in a fixing method in which a visible image formed with toner is fixed on a transfer material by heating and pressing, and an image forming method using the toner.

  Conventionally, as an electrophotographic method, many methods are known as described in Patent Documents 1 to 3. In general, an electrostatic charge image is formed on a photoconductor using a photoconductive substance by various means, and then the electrostatic charge image is developed with toner, using direct or indirect means as necessary, After the toner image is transferred to a transfer material such as paper, it is fixed by heating, pressing, heating and pressing, or solvent vapor to obtain a copy or print. The untransferred toner remaining without being transferred onto the photoreceptor is cleaned by various methods, and the above-described steps are repeated.

  In a full-color or multi-color image forming method, for example, a photosensitive drum (or a photosensitive belt) is uniformly charged by a primary charger, and image exposure is performed by laser light modulated by, for example, a magenta image signal of an original. Then, an electrostatic charge image is formed on the photosensitive drum, and the electrostatic charge image is developed by a magenta developer holding magenta toner to form a magenta toner image on the photosensitive drum. The magenta toner image on the photosensitive drum is transferred onto the intermediate transfer member. Next, similarly to the case of magenta toner, the second color development and transfer, the third color development and transfer, and the fourth color development and transfer are performed. The four-color toner image is transferred from the intermediate transfer member having the four-color toner images to the transfer material, and the four-color toner images on the transfer material are fixed by a heat and pressure fixing unit, so that a full-color or multi-color image is obtained. Is formed on the transfer material.

  In a full-color or multi-color image forming method using four photosensitive drums and a transfer belt, a first color toner image is formed on a first photosensitive drum, and a second color is formed on a second photosensitive drum. A toner image is formed, a third color toner image is formed on the third photosensitive drum, a fourth color toner image is formed on the fourth photosensitive drum, and the transfer material on the transfer belt is moved. The first to fourth color toner images on the first to fourth photosensitive drums are sequentially transferred onto a transfer material, and the first to fourth color toner images on the transfer material are fixed by a heat and pressure fixing unit, thereby transferring the material. A full-color or multi-color image is formed.

  In a full-color or multi-color image using one photosensitive drum (or photosensitive belt) and a transfer drum for carrying a transfer material, a first color toner image is formed on the photosensitive drum, and then the first color The color toner transfer is transferred from the photosensitive drum to the transfer material on the transfer drum, and the second to fourth color toner images are similarly transferred onto the transfer material on the transfer drum to have the first to fourth color toner images. The transfer material is separated from the transfer drum, conveyed to a heat and pressure fixing means and fixed, and a full-color or multi-color image is formed on the transfer material.

  In a full-color or multi-color image forming method, a plurality of color toner images are laminated on a transfer material and fixed by heating and pressing. Therefore, a low-temperature offset and a high-temperature offset are generated compared to a mono-color image forming method. Cheap.

  Conventionally, a method of adding a wax such as a low molecular weight polyolefin into toner particles has been proposed in order to give the toner itself good fixing properties and offset resistance. For example, it is proposed in Patent Documents 4 to 13.

  As one of the wax components having a relatively good fixing property, a toner having a toner particle containing a montan wax, which is a mineral wax, has been proposed.

  As the montan wax, the following structural formula

〔式中、Ｒは炭素数２８〜３２個の炭化水素基、ｎは整数を示す。〕
で示される分子量約８００のワックス成分を用いることが特許文献１４や１５に提案されている。

[Wherein, R represents a hydrocarbon group having 28 to 32 carbon atoms, and n represents an integer. ]
Patent Documents 14 and 15 propose the use of a wax component having a molecular weight of about 800 represented by

  However, the montan wax has a linear structure, has a high plasticizing effect, and softens the toner, so that the low temperature fixability is improved to some extent, but the high temperature offset resistance is lowered. The plasticized toner tends to have problems in development characteristics, durability, and blocking resistance.

  Patent Document 16 proposes a toner containing a polyglycerol partial ester compound. For example, polyglycerin is represented by the following formula:

〔式中、ｎは１以上の整数を示す。〕
で示される。ポリグリセリン部分エステル化合物は、ポリグリセリンのＯＨ基が残存しているエステル化合物である。すなわち、ポリグリセリン部分エステル化合物は、ポリグリセリンのＯＨ基が全てエステル化されている化合物を実質的に含有していない。ポリグリセリン部分エステル化合物は、残存ＯＨ基により紙への親和性が高まる反面、高温高湿環境下においてトナーに対し、摩擦帯電特性の低下や解像性の低下の原因となりやすい。また、重合性単量体組成物から水系媒体中で直接的にトナー粒子を生成する場合、ポリグリセリン部分エステル化合物を含有している重合性単量体組成物は、ポリグリセリン部分エステル化合物が有する残存ＯＨ基に起因して水系媒体中での造粒が困難であり、生成するトナー粒子の粒度分布が広くなりやすい。

[Wherein n represents an integer of 1 or more. ]
Indicated by The polyglycerol partial ester compound is an ester compound in which the OH group of polyglycerol remains. That is, the polyglycerol partial ester compound does not substantially contain a compound in which all of the OH groups of the polyglycerol are esterified. The polyglycerin partial ester compound increases the affinity for paper due to residual OH groups, but tends to cause a decrease in frictional charging characteristics and a decrease in resolution with respect to the toner in a high temperature and high humidity environment. Moreover, when producing | generating a toner particle directly in an aqueous medium from a polymerizable monomer composition, the polymerizable monomer composition containing the polyglycerol partial ester compound has the polyglycerol partial ester compound. Due to residual OH groups, granulation in an aqueous medium is difficult, and the particle size distribution of the toner particles to be generated tends to be wide.

  Patent Document 17 proposes a toner produced by a suspension polymerization method. In the suspension polymerization method, a polymerizable monomer and a colorant (in addition, a polymerization initiator, a crosslinking agent, a charge control agent, a wax and other additives as necessary) are uniformly dissolved or dispersed to form a polymerizable monomer. After preparing the body composition, the polymerizable monomer composition is dispersed and granulated in an aqueous medium containing a dispersion stabilizer using an appropriate stirrer, and subjected to a polymerization reaction to obtain a desired particle size. The toner particles having the above are produced.

  In the suspension polymerization method, in order to generate droplets of the polymerizable monomer composition in a dispersion medium having a large polarity such as water, the component having a polar group contained in the polymerizable monomer composition is an aqueous medium. The non-polar component can easily form a core / shell structure existing in the surface layer portion of the interface with the inside.

The toner particles directly generated by the polymerization method can be compatible with the conflicting performances of low-temperature fixability, blocking resistance and high-temperature offset resistance by encapsulating the wax component as a release agent. High temperature offset can be prevented without applying a release agent such as oil to the roller. Therefore, there is a need for an ester wax that can produce good toner particles even when toner particles are produced by a polymerization method.
US Pat. No. 2,297,691 Japanese Patent Publication No.42-23910 Japanese Patent Publication No.43-24748 Japanese Patent Publication No.52-3304 Japanese Patent Publication No.52-3305 Japanese Patent Publication No.57-52574 JP 58-215659 A JP-A-60-217366 JP-A-60-252361 Japanese Patent Laid-Open No. Sho 62-14166 JP-A-1-109359 Japanese Patent Laid-Open No. 2-79860 Japanese Patent Laid-Open No. 3-50559 JP-A-1-185660 JP-A-1-238672 JP-A-4-184350 Japanese Patent Publication No. 36-10231

  An object of the present invention is to provide a toner for developing an electrostatic charge image in which the above problems are eliminated.

  An object of the present invention is to provide a toner for developing an electrostatic image that is excellent in low-temperature fixability and high-temperature offset resistance.

  An object of the present invention is to provide a toner for developing an electrostatic image for heat and pressure fixing, which has a low pressure dependency and exhibits a good fixing property even at a low pressure.

  An object of the present invention is to provide a toner for developing an electrostatic charge image in which contamination to a carrier, a developing sleeve, a coating blade, an electrostatic charge image carrier, an intermediate transfer member and the like is suppressed.

  An object of the present invention is to provide a toner for developing an electrostatic image having excellent blocking resistance.

  An object of the present invention is to provide a toner for developing an electrostatic image for forming a full-color image, a multi-color image or a mono-color image which is excellent in low-temperature fixability and high-temperature offset resistance.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic charge image that has little fogging, does not cause image missing, and is excellent in developability and dot reproducibility of a digital latent image.

  An object of the present invention is to provide a toner for developing an electrostatic image capable of forming a chromatic color image having excellent translucency.

  An object of the present invention is to provide an electrostatic image developing toner capable of forming a good quality toner image and a fixed image under each environment.

  An object of the present invention is to provide an image forming method using the toner.

The present invention is an electrostatic charge image developing toner having toner particles containing at least a binder resin, a colorant and a wax,
The wax contains at least 50 to 100% by weight (based on the weight of the wax) of an ester compound represented by the following formula (B), (C) or (D) or a mixture thereof: The present invention relates to an image developing toner.

〔式中、Ｒ₄，Ｒ₅，Ｒ₆及びＲ₇は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein, R ₄ , R ₅ , R ₆ and R ₇ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₈，Ｒ₉，Ｒ₁₀及びＲ₁₁は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein R ₈ , R ₉ , R ₁₀ and R ₁₁ are the same or different groups, and each represents an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₁₂，Ｒ₁₃，Ｒ₁₄及びＲ₁₅は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕
さらに、本発明は、電圧が印加されている帯電手段によって静電荷像担持体を帯電し、
帯電された静電荷像担持体を露光して静電荷像を形成し、
静電荷像を現像手段が有するトナーによって現像してトナー画像を静電荷像担持体上に形成し、
静電荷像担持体上のトナー画像を中間転写体を介して、又は、介さずに転写材上にトナー画像を転写し、
転写材上のトナー画像を加熱加圧定着手段によって定着する画像形成方法であり、
該トナーは、結着樹脂，着色剤及びワックスを少なくとも含有するトナー粒子を有し、
該ワックスは、少なくとも下記式（Ｂ），（Ｃ）又は（Ｄ）で示されるエステル化合物又はそれらの混合物を５０〜１００重量％（ワックスの重量基準）含有していることを特徴とする画像形成方法に関する。

[Wherein, R ₁₂ , R ₁₃ , R ₁₄ and R ₁₅ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]
Furthermore, the present invention charges the electrostatic image carrier by charging means to which a voltage is applied,
The charged electrostatic image carrier is exposed to form an electrostatic image,
The electrostatic charge image is developed with toner included in the developing means to form a toner image on the electrostatic charge image carrier,
Transfer the toner image on the transfer material with or without the intermediate transfer member and the toner image on the electrostatic image bearing member;
An image forming method for fixing a toner image on a transfer material by a heat and pressure fixing means,
The toner has toner particles containing at least a binder resin, a colorant and a wax,
The wax contains at least 50 to 100% by weight (based on the weight of the wax) of an ester compound represented by the following formula (B), (C) or (D) or a mixture thereof. Regarding the method.

〔式中、Ｒ₄，Ｒ₅，Ｒ₆及びＲ₇は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein, R ₄ , R ₅ , R ₆ and R ₇ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₈，Ｒ₉，Ｒ₁₀及びＲ₁₁は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein R ₈ , R ₉ , R ₁₀ and R ₁₁ are the same or different groups, and each represents an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₁₂，Ｒ₁₃，Ｒ₁₄及びＲ₁₅は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein, R ₁₂ , R ₁₃ , R ₁₄ and R ₁₅ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

  According to the present invention, by using a specific wax in the toner composition, it has excellent anti-blocking property, exhibits extremely good low-temperature fixability, has no image scattering and fog, and has good dot reproduction and transferability. As a result, a high-quality image can be formed over a long period of time.

  Further, the toner particles on the photosensitive drum and the intermediate transfer member can be transferred with high efficiency without being fused, and matching with the image forming apparatus is also preferable.

  The toner of the present invention contains a wax in the toner particles, and the wax contains at least 50 to 100 weight of an ester compound represented by the following formula (A), (B), (C) or (D) or a mixture thereof. % (Based on the weight of the wax).

〔式中、Ｒ₁，Ｒ₂及びＲ₃は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein R ₁ , R ₂ and R ₃ are the same or different groups, and each represents an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₄，Ｒ₅，Ｒ₆及びＲ₇は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein, R ₄ , R ₅ , R ₆ and R ₇ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₈，Ｒ₉，Ｒ₁₀及びＲ₁₁は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein R ₈ , R ₉ , R ₁₀ and R ₁₁ are the same or different groups, and each represents an organic group having 9 to 39 carbon atoms. ]

〔式中、Ｒ₁₂，Ｒ₁₃，Ｒ₁₄及びＲ₁₅は同一又は異なる基であり、それぞれ炭素数９乃至３９の有機基を示す。〕

[Wherein, R ₁₂ , R ₁₃ , R ₁₄ and R ₁₅ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

  The ester compound (A) is

と酸成分又は酸ハライドとを反応させることにより生成することができる。エステル化合物（Ａ）においては、グリセリン由来のＯＨ基は残存していない。

It can produce | generate by making an acid component or an acid halide react. In the ester compound (A), no glycerol-derived OH group remains.

  The ester compound (B), (C) or (D) is represented by the following formula (b), (c) or (d) as an alcohol component.

で示されるジグリセリンを使用し、ジグリセリンと酸成分又は酸ハライドとを反応させることにより生成することができる。エステル化合物（Ｂ），（Ｃ）及び（Ｄ）においては、ジグリセリン由来のＯＨ基は残存していない。エステル化合物（Ｂ），（Ｃ）及び（Ｄ）の中では、エステル化合物の安定性からエステル化合物（Ｂ）が好ましい。

Can be produced by reacting diglycerin with an acid component or acid halide. In the ester compounds (B), (C) and (D), no diglycerin-derived OH group remains. Among the ester compounds (B), (C), and (D), the ester compound (B) is preferable because of the stability of the ester compound.

  The ester compound (A), (B), (C), (D) or a mixture thereof is preferably 60 to 100% by weight (more preferably 70 to 100% by weight, still more preferably 80 to 100% by weight) based on the wax. The most preferable content is 90 to 100% by weight) in order to improve the low temperature fixing property, high temperature offset resistance, environmental stability and blocking resistance of the toner.

R _{1 to} R ₁₅ are preferably a hydrocarbon group having 9 to 39 carbon atoms, and more preferably an alkyl group having 9 to 39 carbon atoms or an alkenyl group having 9 to 39 carbon atoms. A linear alkyl group having 13 to 39 carbon atoms (most preferably 15 to 25 carbon atoms) is more preferable.

By setting the carbon number of R _{1 to} R ₁₅ to 9 to 39, an appropriate strength can be imparted to the toner particles, and the developability and matching with the image forming apparatus become extremely good. In addition, since such a branched wax improves the dispersion of the constituent components of other toner particles, the developability and transferability are improved synergistically.

The number of carbon atoms can be determined by mass spectral methods such as GC-MS and FD-MS and instrumental analysis such as ¹³ C-NMR. If necessary, the wax may be hydrolyzed by an autoclave method, an enzyme method, or a Witchell method, and the resulting acid component may be measured by instrumental analysis as described above to determine the carbon number.

  The wax has a hydroxyl value (OH value) of 0 to 10 mgKOH / g, more preferably 0.1 to 5.0 mgKOH / g.

  Further, the wax preferably has an acid value of 0 to 10 mgKOH / g, more preferably 0 to 5.0 mgKOH / g.

  If a large amount of glycerin or diglycerin partial ester compound is present in the wax, the partial ester compound has an OH group, so that the hydroxyl value of the wax increases. As the hydroxyl value of the wax exceeds 10 mgKOH / g, the presence of a glycerin or diglycerin partial ester compound in the wax decreases the environmental stability of the toner, and the toner is excessively plasticized to contaminate the carrier and the developing sleeve. It becomes easy, and blocking resistance also falls.

  On the other hand, when a large amount of unreacted carboxylic acid is present in the wax, the acid value of the wax increases. As the acid value of the wax exceeds 10 mgKOH / g, if carboxylic acid free from the wax is present in the wax, the triboelectric charging characteristics of the toner under high temperature and high humidity are reduced, and the fluidity of the toner is also reduced. And dot image reproducibility are reduced.

  In order to suppress the residual amount of glycerin or diglycerin partial ester compound in the wax and reduce the residual amount of free carboxylic acid, the wax has a hydroxyl value of 0.1 to 5.0 mgKOH / g, The value is preferably 0 to 5.0 mgKOH / g.

  The hydroxyl value of the wax is determined by the following method.

  Wax used as a measurement sample is precisely weighed into a 100 ml volumetric flask, 50 ml of xylene is added and dissolved in an oil bath at 120 ° C. Take 50 ml of xylene as a blank in another volumetric flask, and then perform the same operation.

  After dissolution, 5 ml of a mixed solution of acetic anhydride / pyridine (1/4) is added. After heating for 3 hours or more, the oil bath temperature is brought to 80 ° C., a small amount of distilled water is added, and the mixture is kept for 2 hours. Then, it is allowed to cool and the flask wall is washed thoroughly with a small amount of organic solvent. Phenolphthalein (methanol solution) indicator is added, potentiometric titration is performed with 0.5N-KOH / methanol titrant, and the OH value is obtained from the following formula.

OH value = 28.05 × f × (T _b −T _s ) / S + A
S: Sample amount (g)
T _s : Sample titration (ml)
T _b : Blank titration (ml)
f: Titrant factor
A: Acid value of the sample

  Here, the value measured according to "JIS K1557-1970" is used for the acid value (A) of a measurement sample. Specifically, the sample is weighed, dissolved in a mixed solvent, and water is added. This solution is subjected to potentiometric titration with 0.1 N NaOH using a glass electrode to determine the acid value.

  Examples of the method for producing the ester compounds (A), (B), (C) and (D) used in the present invention include a synthesis method by an oxidation reaction, a synthesis from higher fatty acids and derivatives thereof, and a Michael addition. An ester group introduction reaction is used. A particularly preferred production method of the ester compound is a method using a dehydration condensation reaction between a higher fatty acid and glycerin and / or diglycerin as an acid component from the variety of raw materials and ease of reaction (formula 1), or an acid of a higher fatty acid. The reaction of the halide with glycerin and / or diglycerin (Formula 2) is particularly preferred.

  In order to transfer the above ester equilibrium reaction to the production system, the reaction is performed using a large excess of alcohol component or a Dean-Stark water separator in an aromatic organic solvent capable of azeotropy with water. Also, a method of synthesizing an ester by adding a base as an acceptor of an acid by-produced in an aromatic organic solvent using the acid halogen compound can be used.

  Whichever production method is used, the hydroxyl value of the wax is preferably adjusted to a range of 0 to 10 mgKOH / g.

  An antioxidant may be added to the wax within a range that does not affect the chargeability of the toner.

  The wax is solid at room temperature, and has an endothermic main peak at a temperature of 30 to 120 ° C., more preferably at a temperature of 50 to 100 ° C. (more preferably 55 to 80 ° C.) in a DSC endothermic curve measured by a differential thermal analyzer. What has it is preferable in order to improve low temperature fixability, high temperature offset resistance, and blocking resistance.

  The DSC endothermic curve of the wax is measured using a differential thermal analysis measuring device (DSC measuring device), for example, DSC-7 (manufactured by Perkin Elmer) according to ASTM D3418-82. The measurement sample is accurately weighed within the range of 2 to 10 mg. This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rise rate of 10 ° C./min at a temperature rise rate of 10 ° C./min.

  The wax is preferably contained in an amount of 1 to 30 parts by weight (more preferably 2 to 25 parts by weight) with respect to 100 parts by weight of the binder resin in order to improve the low-temperature fixability and high-temperature offset resistance of the toner. If the amount of the wax used is less than 1 part by weight, the effect of adding the wax is hardly exhibited, while if it exceeds 30 parts by weight, the toner blocking resistance and the durability of a large number of sheets are deteriorated.

  In the observation of the tomographic plane of the toner particles using a transmission electron microscope (TEM), the wax may be substantially spherical and / or spindle-shaped and dispersed in an island shape in a state in which the wax is not compatible with the binder resin. preferable. By dispersing the wax in the toner particles as described above and encapsulating the wax in the toner particles, it is possible to satisfactorily prevent toner deterioration and contamination of the image forming apparatus. Therefore, good chargeability is maintained for the toner, and it becomes possible to form a toner image in which a dot image is reproduced well over a long period of time. Further, since the wax component in the toner particles acts efficiently at the time of heating and pressing, the low temperature fixing property and the offset resistance are further improved.

  As a specific method for measuring the tomographic plane of toner particles, the toner particles are sufficiently dispersed in a room temperature curable epoxy resin and then cured in an atmosphere at a temperature of 40 ° C. for 2 days. After ruthenium and, if necessary, dyeing with osmium tetroxide in combination, a flaky sample is cut out using a microtome equipped with diamond teeth, and the tomographic morphology of the toner is measured using a transmission electron microscope (TEM). In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide contrast between materials by utilizing a slight difference in crystallinity between the wax to be used and the resin constituting the outer shell. A typical example is shown in FIG. In the toner particles obtained in Examples described later, it was observed that the wax formed the core particles and the core particles were encapsulated with the outer shell resin.

  In the toner of the present invention, the value of the shape factor SF-1 measured by the image analysis apparatus is 100 to 160, the value of the shape factor SF-2 is preferably 100 to 140, and the value of the shape factor SF-1 Is more preferably 100 to 140, and the shape factor SF-2 is preferably 100 to 120. Further, by satisfying the above conditions and setting the value of (SF-2) / (SF-1) to 1.0 or less, not only the toner characteristics but also matching with the image forming apparatus is extremely good. It will be something.

  For example, SF-1 indicating a shape factor is a random sampling of 100 toner images magnified by 500 times using an FE-SEM (S-800) manufactured by Hitachi, Ltd., and the image information is obtained via an interface. For example, an image analysis apparatus (Luzex III) manufactured by Nicole is introduced for analysis, and a value obtained from the following equation is defined as a shape factor SF-1.

[Where MXLNG indicates the absolute maximum length of the toner particles, and AREA indicates the projected area of the toner particles. ]

  Furthermore, the shape factor SF-2 refers to a value obtained by calculation from the following equation.

[Where PERI indicates the peripheral length of the toner particles, and AREA indicates the projected area of the toner particles. ]

  The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape factor SF-2 indicates the degree of unevenness of the toner particles.

  Conventionally, when the shape factor SF-1 or SF-2 of the toner is small, a cleaning failure is likely to occur, or the external additive is easily embedded in the toner surface when used for a long period of time. As a result, image quality often deteriorates. However, in the present invention, by controlling the polarity of the wax and the state of the branched chain and giving the toner particles appropriate strength, these can be prevented beforehand. On the other hand, when SF-1 exceeds 160, the shape of the toner becomes more irregular, so that the distribution of the triboelectric charge amount of the toner becomes broad and the toner surface is easily ground in the developing unit. This contributes to a decrease in density and image fog. In addition, when an intermediate transfer member is used in the image forming apparatus, a reduction in the transfer efficiency of the toner image at the time of transfer from the electrostatic charge image carrier to the intermediate transfer member is observed, and further, when transferring from the intermediate transfer member to the transfer material. A decrease in toner image transfer efficiency is also observed.

  In order to increase the transfer efficiency of the toner image, the shape factor SF-2 of the toner particles is 100 to 140, and the value of (SF-1) / (SF-2) is preferably 1.0 or less. . When the shape factor SF-2 of the toner particles exceeds 140 and the value of (SF-1) / (SF-2) exceeds 1.0, the surface of the toner particles is not smooth, and the toner particles have many irregularities. Therefore, the transfer efficiency tends to be reduced when transferring from the electrostatic image bearing member to the intermediate transfer member and when transferring from the intermediate transfer member to the transfer material.

  In particular, the above-described tendency becomes apparent when a full-color copying machine that develops / transfers a plurality of toner images is used. That is, in the generation of a full-color image, it is difficult to uniformly transfer four-color toner images. Further, when an intermediate transfer member is used, problems are likely to occur in terms of color unevenness and color balance. It becomes difficult to output stably.

  Further, when a toner having an SF-1 greater than 160 is used, the gap between the photosensitive member and the cleaning member, between the intermediate transfer member and the cleaning member, and / or between the photosensitive member and the intermediate transfer member. It is not preferable because toner fusing and filming are likely to occur on the surface of the photoreceptor and the intermediate transfer member due to the force and rubbing force.

  When an intermediate transfer member is used in order to cope with various types of transfer materials, the transfer process is performed twice, so that a decrease in transfer efficiency causes a decrease in toner utilization efficiency and becomes a problem. In digital full-color copying machines and printers, color image originals are color-separated in advance using a B (blue) filter, G (green) filter, and R (red) filter, and then a dot latent image of 20 to 70 μm is formed on the photoreceptor. Reproduce a multicolor image faithful to the original or original image by using the primary color mixing action using each color toner of Y (yellow) toner, M (magenta) toner, C (cyan) toner, and B (black) toner. There is a need to. At this time, since a large amount of Y toner, M toner, C toner, and B toner is loaded on the photosensitive member or intermediate transfer member in accordance with the color information of the document or CRT, each color toner is transferred extremely high. In order to achieve this, toner whose shape factors SF-1 and SF-2 satisfy the above conditions is preferable.

  In order to develop fine latent image dots faithfully for higher image quality, the toner particles have a weight average diameter of 3 to 10 μm (preferably 4 to 9 μm), and a coefficient of variation (A) in the number distribution. Is 35% or less (more preferably 5 to 34%, still more preferably 5 to 30%). For toner particles having a weight average diameter of less than 3 μm, there are many toner particles remaining on the photosensitive member or intermediate transfer member due to a decrease in transfer efficiency, and this is likely to cause uneven image unevenness due to fog and transfer defects. It is not preferable as a toner used in the present invention. When the weight average diameter of the toner particles exceeds 10 μm, fusion to a member such as the surface of the photoreceptor or an intermediate transfer material tends to occur. This tendency is further enhanced when the coefficient of variation in the number distribution of toner particles exceeds 35%.

  The particle size distribution of the toner particles can be measured by various methods. In the present invention, a Coulter counter was used.

  For example, a Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Inc.) is used as a measuring device, and the number distribution and volume distribution output interface (manufactured by Nikka Ki) and a personal computer are maintained. Prepare approximately 1% NaCl aqueous solution using sodium chloride. For example, ISOTON II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. Using the Coulter counter TA-II, for example, a 100 μm aperture is used as an aperture, and particles having a size of 2 to 40 μm on the basis of the number are used. The particle size distribution is measured and the values according to the invention are then determined.

  The variation coefficient A in the toner particle number distribution is calculated from the following equation.

Coefficient of variation A = [S / D ₁ ] × 100
[In the formula, S represents a standard deviation value in the number distribution of toner particles, and D ₁ represents the number average particle diameter (μm) of toner particles. ]

  Examples of the binder resin used for the toner particles include commonly used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins, and styrene-butadiene copolymers. In a method for directly obtaining toner particles by a polymerization method, a monomer for forming them is used. Specifically, styrene; styrenic monomers such as o (m-, p-)-methylstyrene, m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylic acid ester monomers such as dimethylaminoethyl acrylate, diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile, acrylamide Preferably used. These may be used alone or in general so that the theoretical glass transition temperature (Tg) described in the publication Polymer Handbook 2nd edition III-P139-192 (John Wiley & Sons) is 40-75 ° C. It is used by appropriately mixing the monomer. When the theoretical glass transition temperature is less than 40 ° C., problems are likely to occur from the viewpoint of storage stability and durability stability of the toner, while when it exceeds 75 ° C., the fixing point of the toner is increased. In particular, in the case of a color toner for forming a full-color image, the color mixing property at the time of fixing each color toner is lowered, the color reproducibility is poor, and the transparency of the OHP image is further lowered.

  The molecular weight of the binder resin is measured by gel permeation chromatography (GPC). In the case of toner particles having a core-shell structure, the GPC is measured in advance by extracting toner with a toluene solvent using a Soxhlet extractor for 20 hours in advance, and then distilling off the toluene with a rotary evaporator to obtain an extract. Further, an organic solvent (for example, chloroform) that dissolves the wax but does not dissolve the outer shell resin is added to the extract and thoroughly washed, and then the residue is dissolved in tetrahydrofuran (THF) to obtain a pore size of 0.3 μm. A sample (THF solution) filtered with a solvent resistant membrane filter is measured using 150C manufactured by Waters. The column structure can connect A-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko and measure the molecular weight distribution using a standard polystyrene resin calibration curve. The main peak molecular weight of the resin component of the obtained polymer particles is 5,000 to 1,000,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 to 100. Is preferred.

  In the present invention, it is particularly preferable to add a polar resin to encapsulate the wax in the outer shell. As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a styrene-maleic acid copolymer, an unsaturated polyester resin, a saturated polyester resin or an epoxy resin is preferably used.

  Examples of the colorant used in the present invention include the following yellow colorant, magenta colorant, and cyan colorant. As the black colorant, carbon black, magnetic substance, or yellow colorant / magenta colorant / cyan color shown below. What was mixed with the agent and was toned to black is used.

  As the yellow colorant, compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180, etc. are preferably used.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.

  As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66 can be particularly preferably used.

  These colorants can be used alone or in combination and further in the form of a solid solution. The colorant is selected from the viewpoints of hue, saturation, lightness, weather resistance, OHP transparency, and dispersibility in the toner particles. The added amount of the colorant is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the resin component.

  When a magnetic material is used as the black colorant, it is preferable to use 40 to 150 parts by weight with respect to 100 parts by weight of the resin, unlike other colorants.

  A charge control agent may be added to the toner. As the charge control agent, known ones can be used, and a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Further, when the toner particles are produced directly by a polymerization method, a charge control agent having no polymerization inhibition and no solubilized product in an aqueous dispersion medium is particularly preferable. Specific compounds include metal compounds of aromatic carboxylic acids such as salicylic acid, naphthoic acid and dicarboxylic acid as negative charge control agents; metal salts or metal complexes of azo dyes, metal salts or metal complexes of azo pigments; sulfonic acids Alternatively, polymer compounds having a carboxylic acid group in the side chain; boron compounds; urea compounds; silicon compounds; Examples of the positive charge control agent include quaternary ammonium salts; polymer type compounds having the quaternary ammonium salt in the side chain; guanidine compounds; imidazole compounds. The charge control agent is preferably used in an amount of 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder resin. However, in the present invention, it is not essential to add a charge control agent. When a two-component development method is used, friction charging with a carrier is used, and when a non-magnetic one-component blade coating development method is used, It is not always necessary to include a charge control agent in the toner particles by actively utilizing frictional charging with the blade member or the sleeve member.

  As a method for producing toner particles, resin, wax functioning as a release agent, colorant, charge control agent, etc. are uniformly dispersed using a pressure kneader, an extruder or a media dispersing machine, and then mechanically or jetted. After colliding with the target under an air stream and pulverizing to the desired toner particle size (adding toner particle smoothing and spheroidization if necessary), the particle size distribution is sharpened through a classification step. A method for producing toner by a pulverization method for producing toner particles; a method for obtaining a spherical toner by atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945; and JP-B-36-10231 The toner is directly produced using the suspension polymerization method described in JP-A-59-53856 and JP-A-59-61842. A dispersion polymerization method in which a toner is produced directly using an aqueous organic solvent that is soluble in the monomer and insoluble in the polymer obtained from the monomer, or directly polymerized in the presence of a water-soluble polar polymerization initiator. And a method of producing toner particles using an emulsion polymerization method typified by a soap-free polymerization method.

  In the method of producing toner particles using the pulverization method, it is difficult to keep the toner shape factor SF-1 or SF-2 measured by Luzex within a desired range. In the melt spray method, the SF Even if the −1 value can be set to 100 to 160, the particle size distribution of the obtained toner tends to be wide. On the other hand, in the dispersion polymerization method, the obtained toner shows a very sharp particle size distribution, but the production equipment is used from the viewpoint of the processing of the waste solvent and the flammability of the solvent due to the narrow selection of materials to be used and the use of organic solvents. Complicated and complicated. An emulsion polymerization method typified by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform, but the used emulsifier and polymerization initiator terminals are present on the toner particle surface, and environmental characteristics are likely to deteriorate.

  When the suspension polymerization method is used as a toner production method, the particle size distribution control and particle size control of the toner particles can be controlled by changing the type and amount of a hardly water-soluble inorganic salt or a dispersant that acts as a protective colloid. Predetermined toner particles can be obtained by controlling the mechanical device conditions (for example, the circumferential speed of the rotor, the number of passes, the stirring conditions such as the shape of the stirring blades and the container shape) or the solid content concentration in the aqueous solution.

  Further, a seed polymerization method in which a monomer is further adsorbed on the obtained toner particles and then polymerized using a polymerization initiator can be used.

  When producing toner particles by the polymerization method, the polymerization initiator used is 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1. Azo or diazo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide Peroxide-based polymerization initiators such as methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used. The amount of the polymerization initiator used varies depending on the desired degree of polymerization, but is generally 0.5 to 20% by weight based on the polymerizable monomer. The kind of the polymerization initiator is slightly different depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature.

  In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor or the like may be further added and used.

  When a suspension polymerization method using a dispersion stabilizer is used as a method for producing toner particles, the dispersion stabilizer used is an inorganic compound such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate. , Magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina and the like. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and its salt, starch and the like. These can be used by dispersing in an aqueous phase. These dispersion stabilizers are preferably used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer.

  When an inorganic compound is used as the dispersion stabilizer, a commercially available one may be used as it is, but in order to obtain fine toner particles, fine particles of the inorganic compound may be generated in a dispersion medium. For example, in the case of tricalcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution may be mixed under high-speed stirring.

  For fine dispersion of these dispersion stabilizers, 0.001 to 0.1 parts by weight of a surfactant may be used in combination. This is to promote the intended action of the above dispersion stabilizer, such as sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate. , Calcium oleate and the like.

  When a direct polymerization method is used as a method for producing toner particles, the following production method is possible.

  A polymerizable monomer composition in which a wax, a colorant, a charge control agent, a polymerization initiator and other additives are added to the polymerizable monomer and uniformly dissolved or dispersed by a homogenizer or an ultrasonic disperser, The mixture is dispersed in an aqueous medium containing a dispersion stabilizer by an ordinary stirrer, homomixer or homogenizer. Preferably, granulation is performed by adjusting the stirring speed and stirring time so that the droplets of the polymerizable monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state of the polymerizable monomer composition is maintained by the action of the dispersion stabilizer and precipitation of the particles of the polymerizable monomer composition is prevented. The polymerization is preferably carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving the durability in the image forming method of the present invention, in order to remove the unreacted polymerizable monomer or / and by-products, or The aqueous medium may be partially distilled off from the reaction system by distillation after completion of the reaction. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.

  The toner of the present invention includes a lubricant powder such as a polyethylene fluoride powder, a zinc stearate powder, and a polyvinylidene fluoride powder; an abrasive such as cerium oxide, silicon carbide, and strontium titanate; and a fluid such as silica, titanium oxide, and aluminum oxide. It is preferable to externally add a property improver; an anti-caking agent; a conductivity imparting agent such as carbon black, zinc oxide, and tin oxide.

  In particular, the inorganic fine powder is preferably an inorganic fine powder such as silicate fine powder, titanium oxide, or aluminum oxide. The inorganic fine powder is preferably hydrophobized with a hydrophobizing agent such as a silane coupling agent, silicone oil, or a mixture thereof.

  The external additive is usually used in an amount of 0.1 to 5 parts by weight with respect to 00 parts by weight of the toner particles.

  Next, an image forming method to which the toner of the present invention is applied will be described below with reference to the accompanying drawings.

  In the apparatus system shown in FIG. 1, a developer having cyan toner, a developer having magenta toner, a developer having yellow toner, and a black are added to the developing devices 4-1, 4-2, 4-3, and 4-4. A developer having toner is introduced, and the electrostatic image formed on the electrostatic image carrier (for example, photosensitive drum or photosensitive belt) 1 is developed by a magnetic brush developing system or a non-magnetic one-component system, and each color toner image is exposed to light. Sequentially formed on the drum 1 and transferred to an intermediate transfer member.

  The toner of the present invention can be mixed with a magnetic carrier and developed using, for example, developing means as shown in FIG. Specifically, it is preferable to perform development in a state where the magnetic brush is in contact with the photosensitive drum 13 while applying an alternating electric field. The distance (S-D distance) B between the developer carrying member (developing sleeve) 11 and the photosensitive drum 13 is preferably 100 to 1000 μm for preventing carrier adhesion and improving dot reproducibility. If it is narrower than 100 μm, the supply of developer tends to be insufficient, and the image density becomes low, and if it exceeds 1000 μm, the magnetic lines from the magnet S 1 spread and the density of the magnetic brush decreases, resulting in poor dot reproducibility and restraining the carrier. This weakens the force to cause carrier adhesion.

  The voltage (Vpp) between the peaks of the alternating electric field is preferably 500 to 5,000 V, and the frequency (f) is 500 to 10,000 Hz, preferably 500 to 3,000 Hz. it can. In this case, various waveforms such as a triangular wave, a rectangular wave, a sine wave, or a waveform with a changed duty ratio can be selected and used. When the applied voltage is lower than 500 V, it is difficult to obtain a sufficient image density, and the fog toner in the non-image area may not be recovered satisfactorily. If it exceeds 5,000 V, the electrostatic image may be disturbed via the magnetic brush, resulting in a reduction in image quality.

  By using a two-component developer having a well-charged toner, the anti-fogging voltage (Vback) can be lowered, and the primary charge of the photosensitive drum can be lowered, so that the life of the photosensitive drum is extended. Can be Vback is 150 V or less, more preferably 100 V or less, although it depends on the development system.

  The contrast potential is preferably 200 V to 500 V so that a sufficient image density can be obtained.

  If the frequency is lower than 500 Hz, although it is related to the process speed, charge injection into the carrier occurs, so that the image quality may be deteriorated by carrier adhesion or by disturbing the latent image. If the frequency exceeds 10,000 Hz, the toner cannot follow the electric field and the image quality is likely to deteriorate.

  The contact width (development nip C) of the magnetic brush on the developing sleeve 11 with the photosensitive drum 13 is preferably 3 to 8 mm in order to obtain a sufficient image density, excellent dot reproducibility, and development without carrier adhesion. Good to do. If the development nip C is narrower than 3 mm, it is difficult to satisfactorily satisfy a sufficient image density and dot reproducibility. If the development nip C is wider than 8 mm, developer packing occurs and the operation of the machine stops or the carrier adheres. It becomes difficult to suppress enough. As a method for adjusting the developing nip, the nip width is appropriately adjusted by adjusting the distance A between the developer regulating member 18 and the developing sleeve 11 or by adjusting the distance B between the developing sleeve 11 and the photosensitive drum 13.

  In particular, in a full-color image output that emphasizes halftones, a developing system that uses three or more developing units for magenta, cyan, and yellow and that uses the toner of the present invention to form a digital latent image in particular. In combination with the dot latent image, the dot latent image can be developed faithfully without being affected by the magnetic brush and without disturbing the latent image. Also in the transfer step, a high transfer rate can be achieved by using the toner of the present invention, and therefore high image quality can be achieved in both the halftone part and the solid part.

  Further, in combination with the improvement of the initial image quality, the use of the toner of the present invention can prevent deterioration in image quality even in a large number of copies or prints.

  The toner of the present invention can also be suitably used for one-component development. An example of an apparatus for developing an electrostatic image formed on an electrostatic charge image carrier is shown, but is not necessarily limited thereto.

  In FIG. 3, reference numeral 25 denotes an electrostatic charge image carrier (photosensitive drum or photosensitive belt), and formation of the electrostatic charge image is performed by electrophotographic process means or electrostatic recording means. Reference numeral 24 denotes a toner carrier (developing sleeve), which is a non-magnetic sleeve made of aluminum or stainless steel.

  The substantially right half circumferential surface of the developing sleeve 24 is always in contact with the toner reservoir in the toner container 21, and the toner in the vicinity of the developing sleeve surface is applied to the developing sleeve surface by the magnetic force of the magnetic generating means in the sleeve and / or by electrostatic force. Adhesion is retained.

  The surface roughness Ra (μm) of the toner carrier is set to be 1.5 or less. Preferably it is 1.0 or less. More preferably, it is 0.5 or less.

  By controlling the surface roughness Ra to 1.5 or less, the toner carrying ability of the toner carrying member is suppressed, the toner layer on the toner carrying member is thinned, and the toner carrying member and the toner are separated from each other. Since the number of times of contact is increased, the chargeability of the toner is also improved, so that the image quality is synergistically improved.

  If the surface roughness Ra of the toner carrier exceeds 1.5, it is difficult not only to thin the toner layer on the toner carrier but also to improve the image quality because the chargeability of the toner is not improved. is there.

  The surface roughness Ra of the toner carrier is a center line measured using a surface roughness measuring instrument (Surfcoder SE-30H, manufactured by Kosaka Laboratory Co., Ltd.) based on JIS surface roughness “JIS B 0601”. Corresponds to the average roughness. Specifically, a 2.5 mm portion as the measurement length a is extracted from the roughness curve in the direction of the center line, the center line of this extraction portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness curve is When represented by y = f (x), the value obtained by the following formula is represented in micrometers (μm).

  As the toner carrier used in the present invention, for example, a cylindrical or belt-like member formed of stainless steel or aluminum is preferably used. If necessary, the surface may be coated with another metal or resin, or a resin composition in which fine particles of metal, carbon black, charge control agent or the like are dispersed in the resin may be coated.

  In the present invention, by setting the surface movement speed of the toner carrier to be 1.05 to 3.0 times the surface movement speed of the electrostatic latent image carrier, the toner layer on the toner carrier is Since it receives an appropriate stirring effect, the faithful reproduction of the electrostatic charge image becomes even better.

  When the surface moving speed of the toner carrier is less than 1.05 times the surface moving speed of the electrostatic charge image carrier, the stirring effect received by the toner layer is low and it is difficult to form a good image. Further, when developing a large area such as a solid black image with a large amount of toner, the amount of toner supplied to the electrostatic charge image is insufficient and the image density tends to be thin. On the other hand, if it exceeds 3.0, in addition to the various problems caused by excessive charging of the toner as described above, toner deterioration due to mechanical stress and toner adhesion to the toner carrier are generated and promoted, which is not preferable. .

  The toner T is stored in the hopper 21 and is supplied onto the developing sleeve by the supply member 22. As the supply member, a supply roller made of a foamed material such as a porous elastic body, for example, a flexible polyurethane foam is preferably used. The supply roller is rotated relative to the developing sleeve at a relative speed other than 0 in the forward or reverse direction, and the toner (undeveloped toner) after development on the sleeve is peeled off along with the supply of toner onto the developing sleeve. At this time, the contact width of the supply roller to the developing sleeve is preferably 2.0 to 10.0 mm and more preferably 4.0 to 6.0 mm in consideration of the balance between toner supply and stripping. On the other hand, excessive stress on the toner is inevitably caused, and the toner is liable to increase in aggregation due to the deterioration of the toner or to be fused and fixed to the developing sleeve and the supply roller. Since it has excellent moldability and durability stability, it is preferably used in a developing method having the supply member. Further, a brush member made of resin fibers such as nylon or rayon may be used as the supply member. These supply members are extremely effective in a one-component developing method using a non-magnetic one-component toner that cannot use a magnetic binding force, but may be used in a one-component developing method using a magnetic one-component toner.

  The toner supplied onto the developing sleeve is uniformly applied in a thin layer by the regulating member. The toner thinning regulating member is a doctor blade such as a metal blade or a magnetic blade disposed with a certain gap from the developing sleeve. Alternatively, a rigid roller or sleeve using a material such as metal, resin, or ceramic may be used instead of the doctor blade, and magnetism generating means may be placed inside them.

  An elastic body such as an elastic blade or an elastic roller for press-fitting toner may be used as the toner thinning regulating member. For example, in FIG. 3, the elastic blade 23 is fixedly held at its base, which is the upper side, on the developer container 21 side, and the lower side is bent in the forward or reverse direction of the developing sleeve 24 against the elasticity of the blade. The blade inner surface side (or the outer surface side in the reverse direction) is brought into contact with the surface of the sleeve 24 with an appropriate elastic pressure. According to such an apparatus, it is possible to obtain a dense toner layer that is stable against environmental changes. The reason is not necessarily clear, but it is presumed that charging is always performed in the same state regardless of a change in behavior of the toner due to an environmental change because the elastic body forcibly rubs against the surface of the developing sleeve.

  On the other hand, charging tends to be excessive, and the toner is likely to be fused on the developing sleeve or the elastic blade. However, the toner of the present invention is preferably used because it has excellent releasability and stable tribocharging.

  The elastic body is preferably selected from a triboelectric material suitable for charging the toner to a desired polarity, such as a rubber elastic body such as silicone rubber, urethane rubber or NBR; a synthetic resin elastic body such as polyethylene terephthalate. A metal elastic body such as stainless steel, steel or phosphor bronze can be used. Moreover, those composites may be sufficient.

  Further, when durability is required for the elastic body and the toner carrying body, it is preferable that the metal elastic body is bonded or coated with a resin or rubber so as to contact the sleeve contact portion.

  Furthermore, an organic substance or an inorganic substance may be added to the elastic body, and it may be melt-mixed or dispersed. For example, the chargeability of the toner can be controlled by adding a metal oxide, metal powder, ceramics, carbon allotrope, whisker, inorganic fiber, dye, pigment, or surfactant. In particular, when the elastic body is a molded body of rubber or resin, a metal oxide fine powder such as silica, alumina, titania, tin oxide, zirconia oxide and zinc oxide, carbon black, and a charge control agent generally used for toners are used. It may be included.

  Further, even when a DC electric field and / or an AC electric field is applied to the developing blade as the regulating member, the supply roller as the feeding member, and the brush member, the regulating portion on the developing sleeve is uniform in order to loosen the toner. The thin-layer coating property and the uniform charging property are further improved, and the supply / peeling of the toner is more smoothly performed at the supply site, so that sufficient image density can be achieved and a high-quality image can be obtained.

  The contact pressure between the elastic body and the toner carrier is 0.1 kg / m or more, preferably 0.3 to 25 kg / m, more preferably 0.5 to 12 kg as the linear pressure in the generatrix direction of the toner carrier. / M is effective. As a result, toner aggregation can be effectively loosened, and the toner charge amount can be instantaneously increased. When the contact pressure is less than 0.1 kg / m, it is difficult to uniformly apply the toner, and the toner charge amount distribution becomes broad, causing fog and scattering. On the other hand, if the contact pressure exceeds 25 kg / m, a large pressure is applied to the toner, which is not preferable because the toner deteriorates or toner aggregates are generated. Further, it is not preferable because a large torque is required to drive the toner carrier.

  The gap α between the electrostatic charge image carrier and the toner carrier is set to 50 to 500 μm in the case of jumping development.

  In the case of jumping development, the layer thickness of the toner layer on the toner carrier is preferably thinner than the gap α between the electrostatic image carrier and the toner carrier. Among them, the layer thickness of the toner layer may be regulated so that a part thereof is in contact with the electrostatic charge image carrier.

  On the other hand, an alternating electric field is applied to the toner carrier from the electrostatic charge image carrier by the bias power source 26, thereby facilitating the movement of the toner from the toner carrier to the electrostatic image carrier. Can be obtained. The alternating electric field Vpp is 100 V or more, preferably 200 to 3000 V, more preferably 300 to 2000 V. In addition, a waveform such as a rectangular wave, a sine wave, a sawtooth wave, or a triangular wave can be applied to the waveform in this case where f is used at 500 to 5000 Hz, preferably 1000 to 3000 Hz, more preferably 1500 to 3000 Hz. Also, asymmetrical AC bias with different forward or reverse voltage and application time can be used. It is also preferable to superimpose a DC bias.

The electrostatic image carrier 1 is a photosensitive drum or a photosensitive belt having a photoconductive insulating material layer such as a-Se, Cds, ZnO ₂ , OPC, or a-Si. The electrostatic image carrier 1 is rotated in the direction of the arrow by a driving device (not shown).

  As the electrostatic charge image carrier 1, a photoreceptor having an amorphous silicon photosensitive layer or an organic photosensitive layer is preferably used.

  The organic photosensitive layer may be a single layer type in which the photosensitive layer contains a charge generation material and a substance having charge transport performance in the same layer, or a function-separated type photosensitive layer having the charge generation layer as a component. It may be. A laminated photosensitive layer having a structure in which a charge generation layer and then a charge transport layer are laminated in this order on a conductive substrate is one preferred example.

  The binder resin for the organic photosensitive layer is particularly a polycarbonate resin, a polyester resin, or an acrylic resin, and has good transferability and cleaning properties, and poor cleaning, toner fusion to the photoreceptor, and filming of external additives are unlikely to occur.

  In the charging process, there are a non-contact system using the electrostatic image carrier 1 using a corona charger and a contact system using a roller or the like, and any of them is used. For efficient uniform charging, simplification, and low ozone generation, a contact type as shown in FIG. 1 is preferably used.

  The charging roller 2 is basically composed of a central cored bar 2b and a conductive elastic layer 2a formed on the outer periphery thereof. The charging roller 2 is pressed against the surface of the electrostatic image carrier 1 with a pressing force, and is driven to rotate as the electrostatic image carrier 1 rotates.

  As a preferable process condition when using the charging roller, when the contact pressure of the roller is 5 to 500 g / cm and the AC voltage is superimposed on the DC voltage, the AC voltage is 0.5 to 5 kVpp, AC The frequency is 50 Hz to 5 kHz, the DC voltage is ± 0.2 to ± 1.5 kV, and when only the DC voltage is used, the DC voltage is ± 0.2 to ± 5 kV.

  Other charging means include a method using a charging blade and a method using a conductive brush. These contact charging means are effective in that a high voltage is unnecessary and generation of ozone is reduced.

  The material of the charging roller and charging blade as the contact charging means is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable coating, nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride) can be applied.

  The toner image on the electrostatic charge image carrier is transferred to the intermediate transfer member 5 to which a voltage (for example, ± 0.1 to ± 5 kV) is applied. The surface of the electrostatic image carrier is cleaned by a cleaning unit 9 having a cleaning blade 8.

  The intermediate transfer member 5 includes a pipe-shaped conductive core 5b and a medium-resistance elastic layer 5a formed on the outer peripheral surface thereof. The core 5b may be a plastic pipe with conductive plating.

The medium resistance elastic layer 5a is made of elastic material such as silicone rubber, fluororesin rubber, chloroprene rubber, urethane rubber, EPDM (terpolymer of ethylene propylene diene), carbon black, zinc oxide, tin oxide, carbonized carbon. It is a solid or foamed meat layer in which a conductivity imparting material such as silicon is blended and dispersed to adjust the electric resistance value (volume resistivity) to a medium resistance of 10 ⁵ to 10 ¹¹ Ω · cm.

  The intermediate transfer member 5 is disposed in parallel with the electrostatic charge image carrier 1 so as to be in contact with the lower surface portion of the electrostatic charge image carrier 1 and has an arrow at the same peripheral speed as the electrostatic charge image carrier 1. Rotate counterclockwise.

  The first color toner image formed and supported on the surface of the electrostatic charge image carrier 1 is applied to the intermediate transfer member 5 in the process of passing through the transfer nip where the electrostatic charge image carrier 1 and the intermediate transfer member 5 are in contact with each other. The intermediate transfer is sequentially performed on the outer surface of the intermediate transfer member 5 by an electric field formed in the transfer nip region by the bias.

  If necessary, the surface of the intermediate transfer member 5 is cleaned by the removable cleaning means 10 after the transfer of the toner image onto the transfer material. When there is a toner image on the intermediate transfer member, the cleaning means 10 is separated from the surface of the intermediate transfer member so as not to disturb the toner image.

  A transfer unit is disposed in parallel with the intermediate transfer member 5 and brought into contact with the lower surface of the intermediate transfer member 5. The transfer unit 7 is a transfer roller or a transfer belt, for example, and has the same circumference as the intermediate transfer member 5. Rotates clockwise at the speed of the arrow. The transfer unit 7 may be disposed so as to be in direct contact with the intermediate transfer member 5, or a belt or the like may be disposed between the intermediate transfer member 5 and the transfer unit 7.

  In the case of the transfer roller, the basic configuration is a central cored bar 7b and a conductive elastic layer 7a formed on the outer periphery thereof.

  Common materials can be used for the intermediate transfer member and the transfer roller. By setting the volume resistivity of the elastic layer of the transfer roller to be smaller than the volume resistivity of the elastic layer of the intermediate transfer member, the applied voltage to the transfer roller can be reduced and a good toner image is formed on the transfer material In addition, it is possible to prevent the transfer material from being wound around the intermediate transfer member. In particular, the volume specific resistance value of the elastic layer of the intermediate transfer member is particularly preferably 10 times or more than the volume specific resistance value of the elastic layer of the transfer roller.

For example, the conductive elastic layer 7b of the transfer roller 7 has a volume resistance of 10 ⁶ to 10 ¹⁰ Ω · cm, such as polyurethane, ethylene-propylene-diene terpolymer (EPDM) in which a conductive material such as carbon is dispersed. Made of elastic material. A bias is applied to the cored bar 7a by a constant voltage power source. The bias condition is preferably ± 0.2 to ± 10 kV.

  The toner of the present invention has a high transfer efficiency in the transfer process, a small amount of residual toner, and an excellent cleaning property. Therefore, filming hardly occurs on the electrostatic latent image carrier. Further, even when a multi-sheet durability test is performed, the toner of the present invention is less likely to be buried in the surface of the toner particles than the conventional toner, so that good image quality can be maintained over a long period of time. Particularly, it is preferably used in an image forming apparatus having a so-called reuse mechanism in which transfer residual toner on an electrostatic latent image carrier or intermediate transfer member is removed by a cleaning means such as a cleaning blade, and the recovered transfer residual toner is reused. .

  Next, the toner image on the transfer material 6 is fixed by a heat and pressure fixing means. As a heating and pressure fixing means, there is a heating roller method including a heating roller with a built-in heating element such as a halogen heater and an elastic pressure roller pressed against the heating roller, or a heater through a film. There is a heat fixing method (FIGS. 5 and 6). Since the toner of the present invention is excellent in fixability and offset resistance, it exhibits good matching with the heat and pressure fixing means as described above.

  In the image forming method of the present invention, a one-component developing method in which the electrostatic charge image carrier and the toner layer on the toner carrier are in positive contact may be used. A reversal development method is more preferable as a method for developing an electrostatic image.

  As a condition of the developing step in the image forming method of the present invention, it is essential that the toner carrying member and the surface of the photosensitive member are in contact with each other, and more preferably, a reversal developing method is used. Furthermore, by using the cleaner-less process together, the apparatus can be greatly reduced in size. At this time, a bias of a direct current or alternating current component is applied during development or before and after development, and the potential is controlled so that the development and the remaining toner on the electrostatic charge image carrier (photoconductor) can be collected. At this time, the direct current component is located between the light portion potential and the dark portion potential.

As the toner carrier, there is used a method in which an elastic roller is used, toner is coated on the surface of the elastic roller, and this is brought into contact with the surface of the photoreceptor. In this case, the transfer residual toner is cleaned in the cleaner process simultaneously with the development by the electric field acting between the photosensitive member and the elastic roller facing the surface of the photosensitive member via the toner. It is preferable to have an electric field in a narrow gap between the photoreceptor surface and the toner carrying surface. Therefore, it is possible to use a method in which the elastic rubber of the elastic roller is resistance-controlled in the middle resistance region to keep the electric field while preventing conduction with the surface of the photoreceptor, or a method of providing a thin insulating layer on the surface layer of the conductive roller. . Furthermore, a conductive resin sleeve in which the side facing the surface of the photoreceptor is covered with an insulating material on the conductive roller, or a conductive layer is provided on the side not facing the photoreceptor with the insulating sleeve is also possible. Further, it is possible to employ a configuration in which a rigid roller is used as the toner carrier and the photosensitive member is a flexible material such as a belt. The resistance of the developing roller as the toner carrier is preferably in the range of 10 ² to 10 ⁹ Ω · cm.

  In the case of contact development, if the surface roughness Ra (μm) of the toner carrier is set to be 0.2 to 3.0, both high image quality and high durability can be achieved. The surface roughness Ra correlates with the toner conveying ability and the toner charging ability. When the surface roughness Ra of the toner carrier exceeds 3.0, it is difficult to make the toner layer on the toner carrier thin, and the chargeability of the toner is not improved. Since the toner carrying ability on the surface of the toner carrier is suppressed by setting it to 3.0 or less, the toner layer on the toner carrier is thinned, and the number of contact between the toner carrier and the toner increases. Since the chargeability of the toner is also improved, the image quality is synergistically improved. On the other hand, when the surface roughness Ra is smaller than 0.2, it becomes difficult to control the toner coating amount.

  In the contact development method, the toner carrier may be rotated in the same direction as the peripheral speed of the photosensitive member, or may be rotated in the opposite direction. When the rotation is in the same direction, it is preferable to set the peripheral speed of the toner carrier to be 1.05 to 3.0 times the peripheral speed of the photosensitive member.

In the contact development method, a photosensitive drum or a photosensitive belt having a photoconductive insulating material layer such as a-Se, Cds, ZnO ₂ , OPC, or a-Si is preferably used as the photosensitive member.

  As the binder resin of the organic photosensitive layer in the OPC photoreceptor, polycarbonate resin, polyester resin, and acrylic resin are particularly good in transferability and cleaning properties, poor cleaning, toner fusion to the photoreceptor, and external additives. Filming hardly occurs, which is preferable.

  The one-component contact development method will be described below with reference to the accompanying drawings.

  First, a monochrome image forming method using the cleanerless process will be described with reference to FIG.

  In FIG. 7, 100 is a developing device, 109 is a photosensitive member, 105 is a transfer target such as paper, 106 is a transfer member, 107 is a fixing pressure roller, 108 is a fixing heating roller, and 110 is in contact with the photosensitive member 109. A primary charging member that performs direct charging is shown.

  A bias power source 115 is connected to the primary charging member 110 so as to uniformly charge the surface of the photoconductor 109.

  The developing device 100 contains toner 104 and includes a toner carrier 102 that contacts the photoconductor 109 and rotates in the direction of the arrow. Further, a developing blade 101 for regulating the amount of toner and charging 104 and a toner 104 are attached to the toner carrier 102, and a coating roller that rotates in the direction of the arrow in order to impart toner to the toner by friction with the toner carrier 102. 103. A developing bias power source 117 is connected to the toner carrier 102. A bias power supply 118 is also connected to the application roller 103, and a voltage is set on the negative side of the developing bias when using negatively charged toner, and on the positive side of the developing bias when using positively charged toner. Is done. A transfer bias power supply 116 having a polarity opposite to that of the photoconductor 109 is connected to the transfer member 106. The length in the rotation direction and the development nip width at the contact portion between the photoconductor 109 and the toner carrier 102 are preferably 0.2 mm or greater and 8.0 mm or less. If the thickness is less than 0.2 mm, the development amount is insufficient and a satisfactory image density cannot be obtained, and the recovery ability of the transfer residual toner is lowered. If it exceeds 8.0 mm, the amount of toner supplied becomes excessive, fog suppression is likely to deteriorate, and the wear of the photoreceptor is also adversely affected.

As the toner carrier, an elastic roller having an elastic layer on the surface is preferably used. The hardness of the material of the elastic layer used is preferably 20 to 65 degrees (JIS). The resistance of the toner carrier is preferably in the range of about 10 ² to 10 ⁹ Ω · cm in terms of volume resistance. If it is lower than 10 ² Ω · cm, for example, if there is a pinhole on the surface of the photoconductor 109, an overcurrent may flow. On the other hand, if it is higher than 10 ⁹ Ω · cm, the toner is likely to be charged up by frictional charging, and the image density is likely to be lowered.

The toner coat amount on the toner carrier is preferably 0.1 mg / cm ^{2 to} 1.5 mg / cm ² . If it is less than 0.1 mg / cm ^2, it is difficult to obtain a sufficient image density, and if it exceeds 1.5 mg / cm ^2, it becomes difficult to uniformly triboelectrically charge all individual toner particles, which causes deterioration of fog suppression. It becomes. Furthermore, 0.2 mg / cm ^{2 to} 0.9 mg / cm ² is more preferable.

  The toner coating amount is controlled by the developing blade 101, and the developing blade 101 is in contact with the toner carrier 102 through the toner layer. The contact pressure at this time is preferably in the range of 5 g / cm to 50 g / cm. If it is less than 5 g / cm, in addition to controlling the toner coating amount, uniform frictional charging becomes difficult, which causes deterioration of fog suppression. On the other hand, if it exceeds 50 g / cm, the toner particles are subjected to an excessive load, so that deformation of the particles and fusion of the toner to the developing blade or the toner carrier are likely to occur.

  As the toner coating amount regulating member, a metal blade or a roller may be used in addition to the elastic blade for applying the toner by pressure contact.

  It is preferable to select a frictional charging material suitable for charging the toner to a desired polarity for the elastic regulating member, such as a rubber elastic body such as silicone rubber, urethane rubber or NBR, or a synthetic resin elastic material such as polyethylene terephthalate. Body, metal elastic body such as stainless steel, copper and phosphor bronze can be used. Moreover, those composites may be sufficient.

  Further, when durability is required for the elastic regulating member and the toner carrying member, it is preferable that the metal elastic member is bonded or coated with a resin or rubber so as to contact the sleeve contact portion.

  Furthermore, an organic substance or an inorganic substance may be added to the elastic regulating member, and it may be melt-mixed or dispersed. For example, the chargeability of the toner can be controlled by adding a metal oxide, metal powder, ceramics, carbon allotrope, whisker, inorganic fiber, dye, pigment, or surfactant. In particular, when the elastic body is a molded body such as rubber or resin, fine particles of metal oxide such as silica, alumina, titania, tin oxide, zirconia, and zinc oxide, carbon black, and a charge control agent generally used for toners It is also preferable to contain.

  Furthermore, application of a DC electric field and / or an AC electric field to the regulating member also improves the uniform thin-layer coating property and uniform charging property due to the loosening action on the toner, achieving a sufficient image density and high quality. Images can be obtained.

  In FIG. 7, the primary charging member 110 uniformly charges the photoconductor 109 rotating in the direction of the arrow. The primary charging member used here is a charging roller having a basic configuration of a central core metal 110b and a conductive elastic layer 110a formed on the outer periphery thereof. The charging roller 110 is brought into contact with one surface of the electrostatic charge image carrier with a pressing force, and is driven to rotate as the electrostatic charge image carrier 1 rotates.

  As a preferable process condition when using a charging roller, a contact pressure of the roller is 5 to 500 g / cm, and a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage is used as an applied voltage, although it is not particularly limited. In the present invention, an applied voltage of only a DC voltage is preferably used, and the voltage value in this case is used in a range of ± 0.2 to ± 5 kV.

  Other charging means include a method using a charging blade and a method using a conductive brush. These contact charging means have an effect that a high voltage is unnecessary and generation of ozone is reduced as compared with non-contact corona charging. The material of the charging roller and charging blade as the contact charging means is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable coating, nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride) can be applied.

  Following the primary charging step, an electrostatic charge image corresponding to an information signal is formed on the photoconductor 109 by exposure 111 from the light emitting element, and the electrostatic charge image is developed with toner at a position where it abuts on the toner carrying member 102 to be a visible image. Turn into. Further, when combined with a development system that forms a digital latent image on a photoconductor, it is possible to develop the dot latent image faithfully without disturbing the latent image. Next, the visible image is transferred onto the transfer target 105 by the transfer member 106, and the transfer toner 112 is fixed by passing between the heating roller 108 and the pressure roller 107 together with the transfer target 105. Get. As the heat and pressure fixing means, there is a film other than the heat roller system including a heating roller having a built-in heating element such as a halogen heater and an elastic pressure roller pressed against the heating roller with a pressing force. A system in which heat is fixed by a heater via a heater is also used.

  On the other hand, the untransferred toner 113 that remains on the photosensitive member 109 without being transferred passes between the photosensitive member 109 and the primary charging member 110 and reaches the developing nip again, and is developed by the toner carrying member 102 by the developing device 100. Collected in.

  FIG. 9 shows an image forming method for forming a full-color, multi-color or mono-color image using the developing device unit shown in FIG. 8 as a yellow developing device, a magenta developing device, a cyan developing device, and a black developing device. While explaining.

  9, the same reference numerals as those in FIG. 1 denote the same devices and members.

  The yellow developing device 204-1 has yellow toner, and the yellow developing device 204-1 slides so that the yellow toner layer on the toner carrier 102 comes into contact with the electrostatic charge image carrier (photosensitive drum) 1, The electrostatic charge image is developed and a yellow toner image is formed on the photosensitive drum 1. The yellow toner image on the photosensitive drum 1 is then transferred to the intermediate transfer member 5. After the development is completed, the yellow developing device 204-1 slides to a position where it does not come into contact with the photosensitive drum 1, and instead, the magenta developing device 204-2 slides so that the magenta toner layer on the toner carrier 102 is in contact with the photosensitive drum. Then, the electrostatic charge image is developed to form a magenta toner image on the photosensitive drum 1, and then transferred from the photosensitive drum 1 onto the intermediate transfer member 5. Similarly, development is performed by the cyan developing unit 204-3 and the black developing unit 204-4.

  The order of developing yellow toner, magenta toner, cyan toner and black toner may be changed as necessary.

  In the image forming method shown in FIG. 9, a transfer belt 215 is used as a secondary transfer unit.

  The transfer belt 215 is disposed in parallel with the rotation axis of the intermediate transfer member 5 so as to be in contact with the lower surface portion. The transfer belt 215 is supported by a bias roller 214 and a tension roller 212, and a desired secondary transfer bias is applied to the bias roller 214 by a secondary transfer bias source 223, and the tension roller 212 is grounded.

  A primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive drum 1 to the intermediate transfer member 5 is applied from a bias power source 206 with a polarity (+) opposite to that of the toner.

  In the sequential transfer execution process of the first to fourth color toner images from the photosensitive drum 1 to the intermediate transfer member 5, the transfer belt 215 and the intermediate transfer member cleaning roller 207 can be brought into contact with and separated from the intermediate transfer member 5.

  When the color toner image superimposed and transferred onto the intermediate transfer member 5 is transferred to the transfer material P, the transfer belt 215 is brought into contact with the intermediate transfer member 5 and a registration roller 213 from a paper feed cassette (not shown), before transfer. The transfer material P passes through the guide 224 to the contact nip between the intermediate transfer member 5 and the transfer belt 215 at a predetermined timing, and is simultaneously applied to the bias roller 214 from the secondary transfer bias power source 223. A color toner image is transferred from the intermediate transfer member 5 to the transfer material P by the secondary transfer bias. Hereinafter, this process is referred to as secondary transfer.

  The transfer material P that has received the transfer of the toner image is introduced into a heat and pressure fixing device 225 having a heat roller 211 and a pressure roller 210 and is oil-less heat-fixed.

  FIG. 10 shows another multi-color or full-color or mono-color image device.

  In the apparatus shown in FIG. 10, a belt-like intermediate transfer member having a belt 313 and bias means 313a is used as an intermediate transfer member. The fixed solid image of black toner and the fixed solid image of each color toner have a gloss value of 5 to 30 (preferably 10 to 25), and the difference is preferably 5 or less.

  In the electrostatic image carrier 1 used in the present invention, the contact angle of the surface of the electrostatic image carrier with water is preferably 85 degrees or more (preferably 90 degrees or more). When the contact angle with respect to water is 85 degrees or more, the transfer rate of the toner image is improved, and toner filming hardly occurs.

  Examples of ester compounds in ester waxes used in Examples and Comparative Examples are shown below.

  Tables 1 to 5 show the characteristics of the waxes used in the examples and comparative examples.

Example 1
Charge 600 parts by weight of ion-exchanged water and 500 parts by weight of 0.1 mol / liter-Na ₃ PO ₄ aqueous solution into a four-necked flask equipped with a high-speed stirring device TK type homomixer (manufactured by Special Machine Industries) and a baffle plate. The number of revolutions was adjusted to 12000 rpm and heated to 65 ° C. To this, 70 parts by weight of a 1.0 mol / liter-CaCl ₂ aqueous solution was gradually added to prepare an aqueous medium containing a minute hardly water-soluble dispersion stabilizer Ca ₃ (PO ₄ ) ₂ .

-Styrene 78 parts by weight-n-butyl acrylate 22 parts by weight-Carbon black (oil absorption amount = 70 ml / g, pH = 7.0) 10 parts by weight-Polyester resin 4 parts by weight (Mw = 10,800, peak molecular weight = 5200) ,
Tg = 65 ° C., acid value 8.2 mgKOH / g)
-Negative charge control agent (iron complex of dialkyl salicylic acid) 2 parts by weight-Wax F 10 parts by weight

  The above mixture was dispersed for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.) and then 6 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was added to prepare a polymerizable monomer composition. did.

Next, the polymerizable monomer composition is charged into the aqueous medium, and stirred for 15 minutes while maintaining the rotational speed of the high-speed stirrer at 12000 rpm in an N ₂ atmosphere at an internal temperature of 65 ° C. The polymerizable monomer composition was granulated in an aqueous medium. Thereafter, the stirrer was changed to a propeller stirring blade, and the polymerization was completed by maintaining at the same temperature for 10 hours while controlling the particle shape according to the rotation speed of the stirring blade and the angle of the baffle plate.

  After completion of the polymerization, the suspension was cooled, and then diluted hydrochloric acid was added to remove the dispersion stabilizer. Further, washing with water was repeated several times, followed by drying to obtain polymer particles (black toner particles) (A). The polymer particles (A) have a weight average diameter of 5.5 μm, a coefficient of variation in number distribution of 16%, a shape factor SF-1 of 106, SF-2 of 102, (SF-2) / (SF -1) was 0.96, and the molecular weight distribution by gel permeation chromatography (GPC) exhibited a peak molecular weight of 15,000 and Mw / Mn of 18. Further, when the content state of the wax F in the polymer particles (A) was observed with a TEM, it was substantially spherical in a state incompatible with the binder resin as shown in the schematic diagram of FIG. It was included. Wax F was contained in about 10 parts by weight of toner particles (A) per 100 parts by weight of the binder resin component.

100 parts by weight of the polymer particles (A) and 2 parts by weight of a dimethyl silicone oil-treated hydrophobic silica fine powder (BET specific surface area of about 120 m ² / g) were dry-mixed with a Henschel mixer to obtain a black toner (A). . Table 6 shows the physical properties of the black toner particles (A) and the black toner (A).

Examples 2 to 11
Instead of Wax F, Wax A (Example 2), Wax B (Example 3), Wax C (Example 4), Wax D (Example 5), Wax E (Example 6), Wax G (Implementation) Black as in Example 1 except that Example 7), Wax H (Example 8), Wax I (Example 9), Wax J (Example 10) or Wax K (Example 11) is used. Toner particles (B) to (K) were obtained, and further black toners (B) to (K) were obtained. Table 6 shows the physical properties of the obtained black toner particles and black toners (B) to (K).

Comparative Examples 1 to 12
Black toner particles (a), (b) and (e) to (l) were obtained in the same manner as in Example 1 except that the waxes (a) to (l) were used instead of the wax F, and Black toners (a), (b) and (e) to (l) were obtained.

  In Comparative Examples 3 and 4 using the waxes (c) and (d), it is difficult to granulate the polymerizable monomer in the aqueous medium, and the coalescence of the particles is seen during the polymerization. Toner particles could not be produced.

  Table 6 shows the physical properties of the obtained black toner particles (a), (b), and (e) to (l).

Comparative Example 13
Styrene-n-butyl acrylate copolymer 100 parts by weight (copolymerization weight ratio 80:20, weight average molecular weight 130,000,
Main peak molecular weight = 16,000, Mw / Mn = 2.2, Tg = 50 ° C)
-4 parts by weight of polyester resin used in Example 1-10 parts by weight of carbon black used in Example 1-2 parts by weight of negative charge control agent used in Example 1-10 parts by weight of wax (c) Melt and knead with a twin screw extruder, coarsely pulverize the cooled kneaded product with a hammer mill, finely pulverize the coarsely pulverized product with a jet mill, and mix the resulting finely pulverized product with commercially available calcium phosphate fine powder with a Henschel mixer Thereafter, the obtained mixed powder was put into a container containing water, further dispersed in water using a homomixer, the water temperature was gradually raised, and heat treatment was performed at a temperature of 60 ° C. for 2 hours. Thereafter, dilute hydrochloric acid was added to the container to sufficiently dissolve the calcium phosphate on the surface of the finely pulverized particles. The black resin particles were filtered and washed and dried, and then aggregates were removed through a 400 mesh sieve, followed by classification to obtain black toner particles (m). Black toner (m) was obtained in the same manner as in Example 1 using black toner particles (m).

  The wax (c) in the black toner particles (m) was contained in a finely dispersed state as shown in the schematic diagram of FIG.

  Table 6 shows the physical properties of the black toner particles (m) and the black toner (m).

Comparative Example 14
Black toner particles (n) were obtained in the same manner as in Comparative Example 13 except that the wax (d) was used instead of the wax (c), and further a black toner (n) was obtained. Table 6 shows physical properties of the obtained black toner particles (n) and the black toner (n).

Comparative Examples 15 to 17
Black toner as in Example 1 except that instead of wax F, wax (m) (Comparative Example 15), wax (n) (Comparative Example 16) or wax (o) (Comparative Example 17) is used. (O), (p) and (q) were obtained. Table 6 shows the obtained physical properties.

Evaluation of toner blocking resistance:
Evaluation was made in four stages of A, B, C, and D by the following method.

10 g of toner was placed in a 50 ml polycup and allowed to stand in a hot air dryer set at 50 ° C. for 1 week, and then the state of the toner left when the removed polycup was slowly rotated was visually evaluated.
A: Fluidity is not impaired.
B: Although fluidity | liquidity has fallen, fluidity | liquidity is gradually recovered according to rotation of a cup.
C: Although agglomerates are seen, it can be loosened if it strikes with a needle.
D: Granulated or caked to the extent that it does not unravel even when pierced with a needle.

Example 12
A two-component developer was prepared by mixing 5 parts by weight of the black toner A obtained in Example 1 and 95 parts by weight of a silicone resin-coated magnetic ferrite carrier (number average particle size 45 μm). It was introduced into a black developing device 4-4 shown and an image output test was conducted in a mono color mode. The black toner (A) had negative frictional charging characteristics.

  The image forming apparatus (1) used for the evaluation will be described. FIG. 1 is a schematic explanatory view of a cross section of the image forming apparatus (1).

  The photosensitive drum 1 has a photosensitive layer 1b having an organic optical semiconductor on a substrate 1a, and is rotated by a charging roller 2 (conductive elastic layer 2a, cored bar 2b) that rotates in the direction of an arrow and opposes and contacts the photosensitive drum 1b. 1 was charged to a surface potential of about -600V. The exposure 3 is turned on and off on the photosensitive drum 1 according to digital image information by a polygon mirror, thereby forming an electrostatic charge image having an exposure portion potential of −100V and a dark portion potential of −600V. A black toner image was obtained on the photosensitive drum 1 by using a reversal developing method using the developing device 4-4. The black toner image was transferred onto the intermediate transfer member 5 (elastic layer 5a, cored bar 5b as a support), the black toner image was transferred onto the intermediate transfer member 5, and further transferred onto the transfer paper 6. The transfer residual toner on the photosensitive drum 1 was cleaned by the cleaner member 8.

The intermediate transfer member 5 used was a pipe-shaped metal core 5b coated with an elastic layer 5b in which a carbon black conductivity imparting member was sufficiently dispersed in nitrile-butadiene rubber (NBR). The coat layer 5b had a hardness of 30 degrees according to “JIS K-6301” and a volume resistivity of 10 ⁹ Ω · cm. The transfer current required for transfer from the photosensitive drum 1 to the intermediate transfer member 5 is about 5 μA, which was obtained by applying +500 V from the power source to the cored bar 5b.

As the transfer roller 7, a material in which a carbon conductivity imparting member is sufficiently dispersed in an ethylene-propylene-diene terpolymer (EPDM) foam on a core bar 7 b having an outer diameter of 20 mm and a diameter of 10 mm. The elastic layer 7a produced by coating has a volume resistivity of 10 ⁶ Ω · cm, and the standard hardness of “JIS K-6301” indicates a value of 35 degrees. Using. A voltage was applied to the transfer roller to pass a transfer current of 15 μA.

  As the heat and pressure roller fixing device H, a hot roll type fixing device having no oil application function was used. At this time, both the upper roller and the lower roller had a fluororesin surface layer, and the diameter of the roller was 55 mm. The fixing temperature was set to 140 ° C. and the nip width was set to 7 mm.

  Under the above setting conditions, 12 sheets (A4 size) under normal temperature and normal humidity (25 ° C, 60% RH), low temperature and low humidity (15 ° C, 10% RH), or high temperature and high humidity (30 ° C, 80% RH) environment Perform a printout test in a continuous mode in single color (that is, a mode that promotes toner consumption without pausing the developer) while supplying black toner A to the two-component developer at a printout speed of 1 min / min. The obtained printout images were evaluated for the items described below.

  Further, the matching between the image forming apparatus used and the two-component developer was also evaluated.

Evaluation of Printout Image <1> Image Density Evaluation was performed by maintaining the image density when a predetermined number of printouts were completed on ordinary copying machine plain paper (75 g / m ² ). The image density was measured by using a “Macbeth reflection densitometer” (manufactured by Macbeth Co., Ltd.) to measure a relative density with respect to a printout image of a white background portion having a document density of 0.00.
A: 1.40 or more B: 1.35 or more, less than 1.40 C: 1.00 or more, less than 1.35 D: less than 1.00

<2> Dot reproducibility An image of an isolated dot pattern having a small diameter (45 μm) as shown in FIG. 12 was printed out, and the dot reproducibility was evaluated.
A: 2 or less defects / 100 B: 3-5 defects / 100 defects C: 6-10 defects / 100 defects D: 11 defects / 100 defects / 100

<3> Image fog The fog density (%) is calculated from the difference between the whiteness of the white portion of the printout image measured by “Reflectometer” (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper. evaluated.
A: Less than 1.5% B: 1.5% or more, less than 2.5% C: 2.5% or more, less than 4.0% D: 4.0% or more

<4> Image Scattering When the “electric” character pattern shown in FIG. 13A is printed on plain paper (75 g / m ² ) and thick paper (105 g / m ² and 135 g / m ² ), Toner scattering (the state shown in FIG. 13B) was evaluated visually.
A: Almost no occurrence.
B: Minor scattering is observed.
C: Slight scattering is observed.
D: Significant scattering is observed.

<5> Image dropout Character dropout when the “surprise” character pattern shown in FIG. 14A is printed on thick paper (128 g / m ² and 135 g / m ² ) (state shown in FIG. 14B) Was visually evaluated.
A: Almost no occurrence.
B: A slight void is observed.
C: Some voids are observed.
D: Significant void is seen.

<6> Sleeve Ghost After printing out a solid black belt-shaped image X having a width a and a length l shown in FIG. 15A, a length l having a width b (> a) shown in FIG. When the halftone image Y was printed out, the light and dark differences appearing on the halftone image (A, B, and C portions in FIG. 15R> 5 (C)) were visually evaluated.
A: No difference in shading is observed.
B: A slight difference in density is observed between B and C.
C: A slight difference in shading is observed in each of A, B, and C.
D: A remarkable difference in shading is observed.

<7> Fixability Fixability was evaluated based on a reduction rate (%) of the image density before and after rubbing by applying a load of 50 g / cm ² , rubbing the fixed image with soft thin paper.
A: Less than 5% B: 5% or more, less than 10% C: 10% or more, less than 20% D: 20% or more

<8> Offset Resistance Offset resistance was evaluated based on the degree of contamination on an image after 3000 sheets after printing out a sample image having an image area ratio of about 5%.
A: Not generated.
B: Almost no occurrence.
C: Some dirt on the image was seen.
D: Dirt on the image became significant.

Image forming apparatus matching evaluation <1> Matching with developing sleeve After completion of the printout test, the appearance of residual toner on the surface of the developing sleeve and the influence on the printout image were visually evaluated.
A: Not generated.
B: Almost no occurrence.
C: Although there is sticking, the influence on the image is small.
D: There are many sticking and image unevenness occurs.

<2> Matching with photosensitive drum After completion of the printout test, the occurrence of scratches on the surface of the photosensitive drum and the sticking of residual toner and the influence on the printout image were visually evaluated.
A: Not generated.
B: Scratches are slightly observed, but there is no influence on the image.
C: Although there are sticking and scratches, the influence on the image is small.
D: There are many stickings, and vertical streak-like image defects occur.

<3> Matching with intermediate transfer member After completion of the printout test, scratches on the surface of the intermediate transfer member and the fixing state of residual toner were visually evaluated.
A: Not generated.
B: Although the presence of residual toner is recognized on the surface, there is no influence on the image.
C: Although there are sticking and scratches, the influence on the image is small.
D: There are many fixations and image defects occur.

<4> Matching with fixing device After completion of the printout test, scratches on the surface of the fixing film and adhesion of residual toner were visually evaluated.
A: Not generated.
B: Although slight fixation is observed, there is no influence on the image.
C: Although there are sticking and scratches, the influence on the image is small.
D: There are many fixations and image defects occur.

Fixing property The unfixed image is taken out before being fixed by the fixing device of the image forming apparatus shown in FIG. 1, and is subjected to heat and pressure roller fixing while changing the fixing temperature at intervals of 5 ° C. by an external fixing device, so that a low temperature offset does not occur The fixing temperature and the maximum fixing temperature at which no high temperature offset occurs were measured.

  Table 7 shows the evaluation results.

Examples 13 to 22 and Comparative Examples 18 to 32
Evaluation was performed in the same manner as in Example 12 using the black toners (B) to (K) and the black toners (a), (b) and (e) to (q). Table 7 shows the evaluation results.

Examples 23 to 25
Instead of using carbon black as the colorant, 4.5 parts by weight of yellow colorant (CI Pigment Yellow 17), 5.0 parts by weight of magenta colorant (CI Pigment Red 202), or cyan coloration Yellow toner particles, magenta toner particles and cyan toner particles were produced in the same manner as in Example 1 using 5.0 parts by weight of the agent (CI Pigment Blue 15: 3). Similarly, each color toner and each color two-component developer were prepared. In the image forming apparatus shown in FIG. 1, the two-component developer for yellow is put in the developing device 4-1 and the two-component developer for magenta is put in the developing device 4-2, and the two-component developer for cyan is used. Was placed in the developing device of 4-3, the two-component developer for black of Example 1 was put in the developing device of 4-4, and an image output test was performed in the full color mode. A full color image was obtained.

  Table 8 shows the physical properties of yellow toner, magenta toner, and cyan toner.

Example 26 and Comparative Example 33
The black toner (A) or black toner (a) prepared in Example 1 was introduced into the image forming apparatus shown in FIG. 3, and non-magnetic one-component jumping development was performed to perform an image output test. The results are shown in Table 9.

  A monochromatic intermittent mode (that is, one sheet) while sequentially replenishing toner with an image forming apparatus set so that the moving speed of the surface of the developing sleeve 24 is 3.0 times the moving speed of the surface of the photosensitive drum 25. Evaluation was carried out in the same manner as in Example 12 with a mode in which the developing device was paused for 10 seconds each time printing was performed, and toner deterioration was promoted by preliminary operation of the developing device at the time of restart.

  The developing sleeve 24 used here has a surface roughness Ra of 1.5, and the toner regulating blade 23 is made by bonding urethane rubber to a phosphor bronze base plate and coating the contact surface with the developing sleeve 24 with nylon. Using. 5 and 6 is used as the heat and pressure fixing device, the surface temperature of the temperature detecting element 31d of the heating body 31 is 140 ° C., and the heating body 21-a sponge having a silicone rubber foam as a lower layer. The total pressure between the pressure rollers 33 is 8 kg, the nip between the pressure roller and the film is 6 mm, and the fixing film 32 has a low contact material dispersed in PTEF (high molecular weight type) on the contact surface with the transfer material. A heat-resistant polyimide film with a thickness of 60 μm having a resistance release layer was used.

Example 27 and Comparative Example 34
In this embodiment, the image forming apparatus shown in FIG. 4 in which a reuse mechanism is attached and modified to a commercially available laser beam printer LBP-EX (manufactured by Canon Inc.) was used. In the image forming apparatus of FIG. 4, after the untransferred toner on the photosensitive drum 40 is scraped off by the elastic blade 42 of the cleaner 41 in contact with the photosensitive drum, it is sent into the cleaner by the cleaner roller, and further passed through the cleaner screw 43. Then, the supply pipe 44 provided with the conveying screw is returned to the developing unit 46 through the hopper 45, and a system using the collected toner is attached again, and the conductive carbon coated with nylon resin is dispersed as the primary charging roller 47. Using a rubber roller (diameter: 12 mm, contact pressure: 50 g / cm), a dark portion potential V _D = −700 V and a light portion potential V _L = −200 V were formed on the photosensitive drum 40 by laser exposure (600 dpi). The toner carrying member 48 is coated with a resin in which carbon black is dispersed on the surface and has a surface roughness Ra of 1.1. The developing sleeve 48 is 1.1 times the moving speed of the surface of the photosensitive drum 40. Next, the gap (between S and D) between the photosensitive drum 40 and the toner carrier 48 was 270 μm, and a urethane rubber blade was used as a toner regulating member. As a developing bias, an AC bias component is superimposed on a DC bias component. The set temperature of the heat and pressure fixing device H was 150 ° C.

  Under the above setting conditions, black toner (A) at a printout speed of 12 sheets (A4 size) / min in an environment of normal temperature and normal humidity (25 ° C., 60% RH) and low temperature and low humidity (15 ° C., 10% RH). And black toner (o) are replenished one after another and in intermittent mode (that is, a mode in which the developing device is paused for 10 seconds every time one sheet is printed and toner deterioration is promoted by a preliminary operation upon restart). An out test was conducted, and the obtained printout images were evaluated for the items described below.

  Table 10 shows the evaluation results.

Example 28
500 parts by weight of 0.1M Na ₃ PO ₄ aqueous solution is added to 650 parts by weight of ion-exchanged water in a four-necked flask equipped with a baffle plate and heated to 60 ° C. It stirred at 12000 rpm using the mixer (made by a special machine chemical industry). To this, 70 parts by weight of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing a minute water-insoluble dispersion stabilizer.

Styrene 80 parts by weight n-butyl acrylate 20 parts by weight Polyester resin 4 parts by weight (weight average molecular weight 10600, peak molecular weight 8900,
Acid value 6.3mgKOH / g)
-Colorant (carbon black) 6 parts by weight-Negative charge control agent (iron compound of monoazo dye) 2 parts by weight-Wax F 15 parts by weight

  Among the materials described above, a carbon black masterbatch was produced using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.) with a colorant, an iron compound of a monoazo dye, and styrene. Next, this master batch and the remainder of the above materials were heated to 60 ° C., dissolved and dispersed to obtain a polymerizable monomer mixture. Further, while maintaining the liquid temperature at 60 ° C., 8 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added and dissolved to prepare a polymerizable monomer composition. .

  The polymerizable monomer composition was charged into an aqueous medium in a flask equipped with the homomixer. At a liquid temperature of 60 ° C., the mixture was stirred at 12000 rpm for 20 minutes using a TK homomixer in a nitrogen atmosphere, and the polymerizable monomer composition was granulated in an aqueous medium. Thereafter, the mixture was reacted at a temperature of 60 ° C. for 6 hours while stirring with a paddle stirring blade, and then polymerized at a temperature of 80 ° C. for 8 hours.

After completion of the polymerization reaction, the suspension is cooled, hydrochloric acid is added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water, and dried to obtain black toner particles (I) having a weight average diameter of about 7.4 μm. Obtained.

Hydrophobic silica fine powder (BET specific surface area 120 m ² ) obtained by treating silica fine powder having a BET specific surface area of 200 m ² / g with a silane coupling agent and dimethyl silicone oil with respect to 100 parts by weight of the obtained black toner particles (I). / G) was externally added at 1.5 parts by weight to obtain black toner (I).

  When the tomographic plane of the black toner particles (I) was observed with a TEM, it was observed that the wax F was substantially spherical and encapsulated in a state where it was not compatible with the binder resin.

  The wax F was contained in about 15 parts by weight of toner particles per 100 parts by weight of the binder resin component, and the black toner (I) had a negative tribocharging property. Table 11 shows the physical properties of the obtained black toner (I).

Examples 29 and 30
Black toners (II) and (III) were prepared in the same manner as in Example 28 except that the amount of wax F used was 1.4 parts by weight (Example 29) or 30 parts by weight (Example 30). . Table 11 shows the physical properties of the obtained black toners.

Examples 31 to 35
Example 28 with the exception of using wax A (Example 31), wax B (Example 32), wax C (Example 33), wax D (Example 34) or wax E (Example 35) Similarly, black toners (IV), (V), (VI), (VII) and (VIII) were obtained. Table 11 shows the physical properties of the obtained black toners.

Example 36
710 parts by weight of ion-exchanged water in a four-necked flask equipped with a baffle plate was charged with 520 parts by weight of a 0.1M Na ₃ PO ₄ aqueous solution and heated to a temperature of 60 ° C. It stirred at 12000 rpm using the mixer (made by a special machine chemical industry). To this, 85 parts by weight of a 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing a minute hardly water-soluble dispersion stabilizer.

Styrene 80 parts by weight n-butyl acrylate 20 parts by weight Polyester resin 4 parts by weight (weight average molecular weight 10600, peak molecular weight 8900,
Acid value 6.3mgKOH / g)
Cyan colorant (CI Pigment Blue 15: 3) 5 parts by weight Negative charge control agent 2 parts by weight (Al compound of 2,5-di-tert-butylsalicylic acid)
・ Wax F 15 parts by weight

  Among the above materials, a colorant, an Al compound of di-tert-butylsalicylic acid, and styrene were premixed using Ebara Milder (manufactured by Ebara Seisakusho). Next, the rest of the above material was added to a flask, heated to 60 ° C., dissolved and dispersed to obtain a polymerizable monomer mixture. Further, while maintaining the liquid temperature at 60 ° C., 10 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added and dissolved to prepare a polymerizable monomer composition. .

  The polymerizable monomer composition was charged into an aqueous medium in a flask equipped with the homomixer. At a temperature of 60 ° C., the mixture was stirred at 10,000 rpm for 20 minutes using a TK homomixer in a nitrogen atmosphere, and the polymerizable monomer composition was granulated in an aqueous medium. Thereafter, the mixture was reacted at a temperature of 60 ° C. for 6 hours while stirring with a paddle stirring blade, and then polymerized at a temperature of 80 ° C. for 10 hours.

After completion of the polymerization reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water, and dried to obtain cyan toner particles having a weight average diameter of about 7.0 μm.

  To 100 parts by weight of the obtained cyan toner particles, 1.5 parts by weight of the hydrophobic silica fine powder of Example 28 was externally added to obtain a cyan toner. Table 11 shows physical properties of the obtained cyan toner.

Examples 37 and 38
A magenta toner and a yellow toner are obtained in the same manner as in Example 36 except that a magenta colorant (CI Pigment Red 202) or a yellow colorant (CI Pigment Yellow 17) is used as the colorant. It was. Table 11 shows the physical properties of the obtained toners.

Example 39
Styrene-n-butyl acrylate copolymer 100 parts by weight (weight average molecular weight 141000, copolymerization ratio 80:20)
Polyester resin 4 parts by weight (weight average molecular weight 10600, peak molecular weight 8900,
Acid value 6.3mgKOH / g)
-Colorant (carbon black) 6 parts by weight-Negative charge control agent (iron compound of monoazo dye) 2 parts by weight-Wax F 5 parts by weight

The above materials were mixed in advance and melt kneaded at 130 ° C. with a twin screw extruder. This melt-kneaded product was roughly crushed with a hammer mill to obtain a 1 mm mesh pass toner crushed product. Further, the coarsely pulverized product was finely pulverized by a collision type pulverizer using a jet stream and then classified by wind to obtain black toner particles (IX) having a weight average particle size of 9.4 μm. With respect to 100 parts by weight of the obtained black toner (IX), the surface of the silica fine powder having a specific surface area of 200 m ² / g by BET method is hydrophobized with a silane coupling agent and silicone oil to have a specific surface area of 120 m. 1.0 part by weight of hydrophobic silica fine powder of ² / g was externally added to obtain black toner (IX). Table 11 shows the physical properties of the obtained black toner (IX).

  When the tomographic plane of the black toner particles (IX) was observed with a TEM, it was observed that the wax F was indispensably finely dispersed throughout the toner particles in a state incompatible with the binder resin.

Example 40
A black toner (X) was obtained in the same manner as in Example 39 except that the amount of the wax F used was 15 parts by weight. Table 11 shows the physical properties of the obtained black toner (X).

Example 41
The black toner particles (IX) of Example 39 were added to an aqueous solution containing a surfactant, surface-treated at a temperature of 80 ° C. for 2.5 hours while stirring at a high speed, filtered, washed with water, and dried. Black toner particles (IX) having a weight average diameter of about 9.6 μm were obtained. 1.0 part by weight of hydrophobic silica fine powder of Example 39 was externally added to 100 parts by weight of black toner particles (IX) to obtain black toner (XI). Table 11 shows the physical properties of the obtained black toner (XI).

Comparative Examples 35 to 41
Instead of wax F, wax (a) (Comparative Example 35), wax (b) (Comparative Example 36), wax (e) (Comparative Example 37), wax (h) (Comparative Example 38), wax (m) (Comparative Example 39) Black wax (i), (ii) and (ii) are the same as in Example 28 except that wax (n) (Comparative Example 40) or wax (o) (Comparative Example 41) is used. iii), (iv), (v), (vi) and (vii) were obtained. Table 11 shows the physical properties of the obtained toners.

Examples 42 to 55 and Comparative Examples 42 to 48
As the electrophotographic apparatus, a modified machine in which the process speed of a 600 dpi laser beam printer (Canon: LBP-860) was modified to 60 mm / s was used. A schematic diagram is shown in FIG. The cleaning rubber blade in the process cartridge of the laser beam printer was removed, and the charging method of the apparatus was direct charging performed by contacting the rubber roller 110, and the applied voltage was a direct current component (-1200 V).

Next, the development part in the process cartridge was modified. A medium resistance rubber roller (diameter 16 mm, hardness ASKER C 45 degrees, resistance 10 ⁵ Ω · cm) made of silicone rubber dispersed with carbon black is used as a toner carrier 102 instead of a stainless steel sleeve as a toner supply body. Abutted. The developing nip width at this time was set to about 3 mm. The peripheral rotation speed of the toner carrier 102 is the same in the contact portion with the photosensitive drum 109 and is driven to be 140% with respect to the rotational peripheral speed of the photosensitive drum 109. The developing method is a one-component contact developing method, and the electrostatic image was developed by a reversal developing method.

  As the photosensitive drum 109, an aluminum cylinder having a diameter of 30 mm and a length of 254 mm was used as a base, and layers having the following configurations were sequentially laminated by dip coating to produce the photosensitive drum 109.

(1) Conductive coating layer: Mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenolic resin. Film thickness 15 μm.
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
(3) Charge generation layer: Mainly composed of a titanyl phthalocyanine pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
(4) Charge transport layer: Mainly composed of a hole transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 by Ostwald viscosity method) at a weight ratio of 8:10. Film thickness 20 μm.

  As a means for applying toner to the toner carrier 102, a coating roller 103 made of foamed urethane rubber was provided in the developing device and brought into contact with the toner carrier 102. A voltage of about −550 V was applied to the coating roller 103. Further, a stainless steel blade 101 coated with a resin for controlling the toner coating layer on the toner carrier 102 was attached so that the contact pressure with the toner carrier 102 was about 20 g / cm. Only the DC component (−450 V) was applied during development.

  The electrophotographic apparatus was remodeled and process conditions were set as follows in order to conform to the remodeling of these process cartridges.

The modified device uses a roller charger 110 (applying only a direct current) to uniformly charge the photosensitive drum 109, then exposes the image portion with laser light to form an electrostatic image, and develops the toner image. Then, the toner image was transferred to the transfer material 105 by the transfer roller 106 to which a voltage of +700 V was applied. As for the charging potential of the photosensitive drum 109, the dark portion potential was −580 V and the light portion potential was −150 V. As the transfer material 105, 75 g / m ² paper was used.

  Black toners (I) to (XI), cyan toner, magenta toner, yellow toner and black toners (i) to (vii) were introduced into the process cartridge, and an image output test was performed. The evaluation results are shown in Table 12.

  The evaluation method will be described below.

  The transferability is determined by tape-taping off the transfer residual toner on the photosensitive drum when developing a solid black image of the 20th sheet in the initial stage of durability with a Mylar tape and pasting it on the paper. Evaluation was made by subtracting. Therefore, the smaller the value, the better the transferability.

The toner recoverability in the development process was determined by whether or not an image (so-called ghost image) in a non-image area was generated on the obtained image sample. If the toner remaining on the photosensitive drum without being transferred is recovered in the development process, an image is not generated in the non-printed part. However, if the toner recoverability is not good, the unrecovered toner passes through the transfer process again. The image is transferred onto paper and a ghost image is generated.
A: No ghost occurs B: Good (a level that cannot be confirmed without staring at the image)
C: Ghost is generated, but practical level D: Poor

When ghosting and charging unevenness did not occur, printing was continued up to 2000 sheets. Further, the resolving power at the initial stage of durability was evaluated based on the reproducibility of a small-diameter isolated single dot at 600 dpi, which is easy to close due to the latent image electric field and difficult to reproduce.
A (very good): 5 or less defects in 100 B (good): 6 to 10 defects in 100 C (normal): 11 to 20 defects in 100 D (bad) : 20 or more defects in 100

  The anti-offset property was determined by observing stains occurring on the back side of the first to 100th image samples and counting the number of generated images.

  The fog was measured using a REFECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. The filter was calculated from the following equation using an amberlite filter for cyan toner, a blue filter for yellow toner, and a green filter for other toners. The smaller the value, the less fog.

Example 56
The yellow toner of Example 38 is introduced into the yellow developing unit 204-1 of the image forming apparatus shown in FIG. 9, the magenta toner of Example 37 is introduced into the magenta developing unit 204-2, and the cyan developing unit 204-3 is implemented. The cyan toner of Example 38 was introduced, and the black toner (I) of Example 28 was introduced into a black developer, and a full color image output test was performed.

  The photosensitive drum 1 has a photosensitive layer 1b having an organic optical semiconductor on a substrate 1a. The photosensitive drum 1 is rotated by a charging roller 2 (conductive elastic layer 2a, cored bar 2b) that rotates in the direction of an arrow and rotates oppositely. 1 was charged to a surface potential of about -600V. In exposure 3, a digital electrostatic charge image having an exposure portion potential of −100 V and a dark portion potential of −600 V was formed by turning on and off the photosensitive drum 1 according to digital image information by a polygon mirror. Using the developing devices 204-1, 204-2, 204-3, and 204-4, the electrostatic image formed on the photosensitive drum 1 is reversely developed by a non-magnetic one-component contact development method, and each color toner image is exposed to light. Sequentially formed on the drum 1. The toner images were sequentially transferred onto the intermediate transfer member 5 after development for each color, and finally transferred onto the transfer member P at once. At this time, the toner remaining on the photosensitive drum 1 without being transferred was cleaned by the cleaner member 8, and the toner remaining on the intermediate transfer member 5 was charged by the charging means 207 and transferred to the photosensitive drum 1 for cleaning.

The intermediate transfer member 5 is obtained by coating an elastic layer 5a in which a carbon black conductivity imparting member is sufficiently dispersed in nitrile-butadiene rubber (NBR) on a pipe-shaped metal core 5b, and the hardness of the coating layer 5a. Was 20 degrees according to “JIS K6301”, and the volume resistivity was 10 ⁹ Ω · cm. In this embodiment, the transfer from the photosensitive drum 1 to the intermediate transfer body 5 was performed by applying +700 V to the core metal 5b from the power source 206. The roller 214 for charging the transfer belt 215 has an outer diameter of 20 mm, and the roller 214 is an ethylene-propylene-diene terpolymer (EPDM) having a carbon conductivity imparting member on a core metal having a diameter of 10 mm. An elastic layer produced by coating a well-dispersed material in a foam with a volume resistivity value of 10 ⁶ Ω · cm, and the standard hardness of “JIS K6301” is 35 degrees. Those showing values were used. A voltage was applied to the roller to pass a transfer current of 11 μA. As the heat fixing device 225, a heat roll type fixing device having no oil application function was used.

  Under the above setting conditions, durability evaluation was performed by continuous printing at a temperature of 30 ° C./humidity 85% and an image with a printing area of 7% at a sheet passing speed of 8 sheets / minute (A4 size).

  As a result, no ghost or back stain was observed, and there was no problem in image density and transferability up to 2000 full color prints, and a full color image excellent in color faithful to the original image was obtained.

1 is a schematic explanatory view of an image forming apparatus for forming a full-color, multi-color or mono-color image suitable for the image forming method of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of a developing device for a two-component developer used in an example of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of a developing device for a one-component developer used in an example of the present invention. FIG. 2 is a schematic explanatory diagram of an image forming apparatus that reuses untransferred toner. FIG. 3 is an exploded perspective view of a main part of the fixing device. FIG. 4 is an enlarged cross-sectional view of a main part showing a film state when the fixing device is not driven. It is a schematic explanatory drawing of the image forming method by the one-component contact developing method. It is a schematic explanatory drawing of the developing device unit for implementing the one-component contact developing method. It is a schematic explanatory drawing for demonstrating the image formation method of this invention for forming a full color, a multicolor, or a monocolor image. It is a schematic explanatory drawing for demonstrating the image formation method of this invention for forming a full color, a multicolor, or a monocolor image. FIG. 3 is a schematic diagram illustrating an example of a cross section of a toner particle including a wax component. FIG. 6 is an explanatory diagram of an isolated dot pattern for checking toner development characteristics. It is a schematic diagram which shows the state of scattering of a character image. It is a schematic diagram which shows the state of the hollow of a character image. It is explanatory drawing of a sleeve ghost.

Explanation of symbols

1 Photoconductor (electrostatic latent image carrier)
2 Charging roller 3 Exposure 4 4-color developing device (4-1, 4-2, 4-3, 4-4)
5 Intermediate transfer body 6 Transfer material 7 Transfer roller 11 Developer carrier 13 Photosensitive drum 30 Stay 31 Heating body 31a Heater substrate 31b Heat generating body 31c Surface protection layer 31d Temperature detecting element 32 Fixing film 33 Pressure roller 34 Coil spring 35 Film edge Part restricting flange 36 Power supply connector 37 Power disconnecting member 38 Inlet guide 39 Outlet guide (separation guide)

Claims (96)

An electrostatic image developing toner having toner particles containing at least a binder resin, a colorant, and a wax, wherein the wax is at least an ester compound represented by the following formula (B), (C), or (D): A toner for developing an electrostatic image, comprising 50 to 100% by weight (based on the weight of wax).

[Wherein, R ₄ , R ₅ , R ₆ and R ₇ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

[Wherein R ₈ , R ₉ , R ₁₀ and R ₁₁ are the same or different groups, and each represents an organic group having 9 to 39 carbon atoms. ]

[Wherein, R ₁₂ , R ₁₃ , R ₁₄ and R ₁₅ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]   2. The electrostatic image developing toner according to claim 1, wherein the wax contains 60 to 100% by weight of an ester compound represented by the formula (B).   The electrostatic image developing toner according to claim 1, wherein the wax contains 70 to 100% by weight of an ester compound represented by the formula (B).   4. The electrostatic image developing toner according to claim 1, wherein the wax contains 80 to 100% by weight of an ester compound represented by the formula (B).   The electrostatic image developing toner according to claim 1, wherein the wax contains 90 to 100% by weight of an ester compound represented by the formula (B). 6. The electrostatic image developing toner according to claim 1, wherein R _{4 to} R ₁₅ are hydrocarbons. 7. The electrostatic image developing toner according to claim 1, wherein R _{4 to} R ₁₅ are an alkyl group or an alkenyl group. 8. The electrostatic image developing toner according to claim 1, wherein R _{4 to} R ₁₅ are linear alkyl groups having 13 to 29 carbon atoms. 9. The electrostatic image developing toner according to claim 1, wherein R _{4 to} R ₁₅ are linear alkyl groups having 15 to 25 carbon atoms.   The electrostatic image developing toner according to claim 1, wherein the wax has a hydroxyl value of 0 to 10 mg KOH / g.   11. The toner for developing an electrostatic charge image according to claim 1, wherein the wax has a hydroxyl value of 0.1 to 5.0 mgKOH / g.   The toner for developing an electrostatic charge image according to claim 1, wherein the wax has an acid value of 0 to 10 mg KOH / g.   The electrostatic image developing toner according to claim 1, wherein the wax has an acid value of 0.1 to 5.0 mg KOH / g.   The electrostatic image developing toner according to claim 1, wherein the wax has a hydroxyl value of 0 to 10 mg KOH / g and an acid value of 0 to 10 mg KOH / g.   The electrostatic image developing toner according to claim 1, wherein the wax has a hydroxyl value of 0.1 to 5.0 mgKOH / g and an acid value of 0.1 to 5.0 mgKOH / g. .   The electrostatic image development according to any one of claims 1 to 15, wherein the wax is solid at a temperature of 25 ° C, and an endothermic main peak has a temperature of 50 to 100 ° C in an endothermic curve by a differential thermal analysis measuring device. toner.   17. The electrostatic image developing toner according to claim 1, wherein the wax is contained in 1 to 30 parts by weight of toner particles per 100 parts by weight of the binder resin.   18. The toner for developing an electrostatic charge image according to claim 1, wherein the wax is contained in 2 to 25 parts by weight of toner particles per 100 parts by weight of the binder resin.   The electrostatic image developing toner according to claim 1, wherein the wax forms a core part of toner particles.   20. The electrostatic image developing toner according to claim 1, wherein the wax forms a core part of toner particles and is contained in the toner particles in a spherical or spindle shape.   21. The toner for developing an electrostatic charge image according to claim 1, wherein the toner has a shape factor SF-1 of 100 to 160 and a shape factor SF-2 of 100 to 140.   The toner for developing an electrostatic charge image according to any one of claims 1 to 21, wherein the toner has a shape factor SF-1 of 100 to 140 and a shape factor SF-2 of 100 to 120.   The toner for developing an electrostatic charge image according to any one of claims 1 to 22, wherein the toner has a value of SF-2 / SF-1 of 1.0 or less.   The toner for developing an electrostatic charge image according to any one of claims 1 to 23, wherein the toner has a weight average particle diameter of 3 to 10 µm and a coefficient of variation in number distribution of 35 or less.   25. The electrostatic image developing toner according to claim 1, wherein the toner has a weight average particle diameter of 4 to 9.9 μm and a coefficient of variation in number distribution of 35 or less.   26. The toner for developing an electrostatic charge image according to claim 1, wherein the toner has a coefficient of variation of 5 to 34.   27. The electrostatic image developing toner according to claim 1, wherein the toner has a coefficient of variation of 5 to 30.   28. The electrostatic image developing toner according to claim 1, wherein the binder resin is a styrene-acrylate copolymer.   28. The electrostatic image developing toner according to claim 1, wherein the binder resin is a styrene-methacrylate copolymer.   28. The electrostatic image developing toner according to claim 1, wherein the binder resin is a polyester resin.   28. The electrostatic image developing toner according to claim 1, wherein the binder resin is an epoxy resin.   32. The toner for developing an electrostatic charge image according to claim 1, wherein the toner particles have an external additive on the surface thereof.   33. The electrostatic image developing toner according to claim 32, wherein the external additive is externally added in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles.   34. The electrostatic image developing toner according to claim 32, wherein the external additive is an inorganic fine powder.   35. The electrostatic image developing toner according to claim 34, wherein the inorganic fine powder is treated with silicone oil.   The toner particles are obtained by granulating a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, a wax and a polymerization initiator in an aqueous medium, and then polymerizable monomer in the aqueous medium. 36. The electrostatic image developing toner according to claim 1, wherein the toner is produced by polymerizing a polymerizable monomer in the particles of the composition.   37. The electrostatic image developing toner according to claim 36, wherein the polymerizable monomer composition further contains a polar resin.   38. The electrostatic image developing toner according to claim 36 or 37, wherein the polymerizable monomer contains at least a styrene monomer.   39. The electrostatic image developing toner according to claim 36, wherein the polymerizable monomer composition contains at least a styrene monomer and a polyester resin. The electrostatic image carrier is charged by charging means to which a voltage is applied,
The charged electrostatic image carrier is exposed to form an electrostatic image,
The electrostatic charge image is developed with toner included in the developing means to form a toner image on the electrostatic charge image carrier,
Transfer the toner image on the transfer material with or without the intermediate transfer member and the toner image on the electrostatic image bearing member;
An image forming method for fixing a toner image on a transfer material by a heat and pressure fixing means,
The toner has toner particles containing at least a binder resin, a colorant and a wax,
The wax contains at least 50 to 100% by weight (based on the weight of the wax) of an ester compound represented by the following formula (B), (C) or (D) or a mixture thereof. Method.

[Wherein, R ₄ , R ₅ , R ₆ and R ₇ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]

[Wherein R ₈ , R ₉ , R ₁₀ and R ₁₁ are the same or different groups, and each represents an organic group having 9 to 39 carbon atoms. ]

[Wherein, R ₁₂ , R ₁₃ , R ₁₄ and R ₁₅ are the same or different groups, each representing an organic group having 9 to 39 carbon atoms. ]   41. The image forming method according to claim 40, wherein the electrostatic charge image is developed with a two-component developer having at least a toner and a magnetic carrier.   41. The image forming method according to claim 40, wherein the electrostatic charge image is developed with a one-component developer having at least toner.   The developing means has a toner carrier for carrying and transporting toner, and in the development area where the electrostatic image carrier and the toner carrier are closest to each other, 1. 43. The image forming method according to claim 40, wherein the toner carrier rotates at a peripheral speed of 05 to 3.0 times.   44. The image forming method according to claim 43, wherein the toner carrier has a surface roughness Ra (μm) of 1.5 or less, and the toner has a weight average particle diameter of 3 to 10 μm.   The developing means includes a toner carrier for carrying and transporting toner, and a toner layer regulating member for forming a toner layer on the toner carrier, and the toner layer regulating member has an elastic blade. 45. The image forming method according to any one of 44.   46. The image forming method according to claim 43, wherein a thickness of the toner layer formed on the toner carrier is thinner than a gap between the toner carrier and the electrostatic image carrier.   46. The image forming method according to claim 43, wherein the toner layer on the toner carrier is in contact with the electrostatic charge image carrier in the development region.   48. The image forming method according to claim 47, wherein the toner layer on the toner carrier is pressed to the electrostatic image carrier by the toner carrier in the development region.   49. The image forming method according to claim 40, wherein the electrostatic image carrier is charged by bringing a charging member to which a bias is applied into contact therewith.   The image forming method according to claim 49, wherein the charging member is a charging roller.   51. The image forming method according to claim 40, wherein the electrostatic image formed by exposure is a digital latent image.   The developing means has a developer carrier for carrying and transporting a two-component developer having at least toner and a magnetic carrier, and an alternating electric field is applied to the developer carrier. The image forming method according to any one of the above.   The toner image on the electrostatic charge image bearing member is transferred to an intermediate transfer member, and transferred by a transfer roller having a bias applied from the intermediate transfer member to a transfer material or a transfer belt having a roller to which a bias is applied. 53. The image forming method according to claim 40.   54. The heat and pressure fixing step includes heating and pressure fixing a toner image to a transfer material by a heat fixing device that does not supply an offset prevention liquid or does not have a fixing device cleaner. The image forming method described.   In the heat and pressure fixing step, the toner image is heated and pressed on the transfer material by a fixedly supported heating body and a pressure member that is in pressure contact with the heating body and is in close contact with the heating body through a film. 54. The image forming method according to claim 40, wherein the image is fixed.   After the transfer, the untransferred residual toner on the electrostatic image carrier is cleaned and recovered, and the recovered toner is supplied to the developing device and held in the developing device again, so that the electrostatic image on the electrostatic image carrier is obtained. The image forming method according to any one of claims 40 to 55, wherein development is performed.   The electrostatic charge image is successively developed with a toner selected from the group consisting of yellow toner, magenta toner, cyan toner and black toner, and each color toner image is laminated on the intermediate transfer member. 57. The image forming method according to claim 40, wherein the image is transferred onto a transfer material, and each color toner image on the transfer material is heated and pressed to form a full-color image or a multi-color image.   58. The image forming method according to claim 40, wherein the wax contains 60 to 100% by weight of an ester compound represented by the formula (B).   58. The image forming method according to claim 40, wherein the wax contains 70 to 100% by weight of an ester compound represented by the formula (B).   58. The image forming method according to claim 40, wherein the wax contains 80 to 100% by weight of an ester compound represented by the formula (B).   58. The image forming method according to claim 40, wherein the wax contains 90 to 100% by weight of an ester compound represented by the formula (B). R ₄ to R ₁₅ are an image forming method according to any one of claims 40 to 61 is a hydrocarbon. 63. The image forming method according to claim 40, wherein R _{4 to} R ₁₅ are an alkyl group or an alkenyl group. 64. The image forming method according to claim 40, wherein R _{4 to} R ₁₅ are straight-chain alkyl groups having 13 to 29 carbon atoms. 65. The image forming method according to claim 40, wherein R _{4 to} R ₁₅ are linear alkyl groups having 15 to 25 carbon atoms.   66. The image forming method according to claim 40, wherein the wax has a hydroxyl value of 0 to 10 mgKOH / g.   67. The image forming method according to claim 40, wherein the wax has a hydroxyl value of 0.1 to 5.0 mgKOH / g.   68. The image forming method according to claim 40, wherein the wax has an acid value of 0 to 10 mg KOH / g.   69. The image forming method according to claim 40, wherein the wax has an acid value of 0.1 to 5.0 mgKOH / g.   70. The image forming method according to claim 40, wherein the wax has a hydroxyl value of 0 to 10 mgKOH / g and an acid value of 0 to 10 mgKOH / g.   71. The image forming method according to claim 40, wherein the wax has a hydroxyl value of 0.1 to 5.0 mgKOH / g and an acid value of 0.1 to 5.0 mgKOH / g.   The image forming method according to any one of claims 40 to 71, wherein the wax is solid at a temperature of 25 ° C, and an endothermic main peak has a temperature of 50 to 100 ° C in an endothermic curve obtained by a differential thermal analysis measurement device.   73. The image forming method according to claim 40, wherein the wax is contained in 1 to 30 parts by weight of toner particles per 100 parts by weight of the binder resin.   74. The image forming method according to claim 40, wherein the wax is contained in 2 to 25 parts by weight of toner particles per 100 parts by weight of the binder resin.   75. The image forming method according to claim 40, wherein the wax forms a core part of toner particles.   76. The image forming method according to claim 40, wherein the wax forms a core part of toner particles and is contained in the toner particles in a spherical or spindle shape.   77. The image forming method according to claim 40, wherein the toner has a shape factor SF-1 of 100 to 160 and a shape factor SF-2 of 100 to 140.   78. The image forming method according to claim 40, wherein the toner has a shape factor SF-1 of 100 to 140 and a shape factor SF-2 of 100 to 120.   79. The image forming method according to claim 40, wherein the toner has an SF-2 / SF-1 value of 1.0 or less.   80. The image forming method according to claim 40, wherein the toner has a weight average particle diameter of 3 to 10 [mu] m and a coefficient of variation in number distribution of 35 or less.   81. The image forming method according to claim 40, wherein the toner has a weight average particle diameter of 4 to 9.9 μm and a coefficient of variation in number distribution of 35 or less.   82. The image forming method according to claim 40, wherein the toner has a coefficient of variation of 5 to 34.   83. The image forming method according to claim 40, wherein the toner has a coefficient of variation of 5 to 30.   84. The image forming method according to claim 40, wherein the binder resin is a styrene-acrylate copolymer.   The image forming method according to any one of claims 40 to 83, wherein the binder resin is a styrene-methacrylate copolymer.   The image forming method according to any one of claims 40 to 83, wherein the binder resin is a polyester resin.   84. The image forming method according to claim 40, wherein the binder resin is an epoxy resin.   The image forming method according to claim 40, wherein the toner particles have an external additive on the surface.   The image forming method according to any one of claims 40 to 88, wherein the external additive is externally added in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles.   90. The image forming method according to claim 40 or 89, wherein the external additive is an inorganic fine powder.   The image forming method according to claim 90, wherein the inorganic fine powder is treated with silicone oil.   The toner particles are obtained by granulating a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, a wax and a polymerization initiator in an aqueous medium, and then polymerizable monomer in the aqueous medium. 92. The image forming method according to claim 40, which is produced by polymerizing a polymerizable monomer in the particles of the composition.   The image forming method according to claim 92, wherein the polymerizable monomer composition further contains a polar resin.   94. The image forming method according to claim 92 or 93, wherein the polymerizable monomer includes at least a styrene monomer.   95. The image forming method according to claim 92, wherein the polymerizable monomer composition contains at least a styrene monomer and a polyester resin.   96. The image forming method according to claim 40, wherein no cleaning unit is provided between the transfer unit and the downstream charging unit.

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