JPH09230621A - Single component developping toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single component developing toner excellent in the anti- fastening property, low-temp. fixation performance, and the cleaning characteristic for an electrostatic latent image carrier. SOLUTION: A single component developing device 5 is structured so that the toner is charged electrostatically by allowing it to pass through the gap between a developing sleeve 22 and a toner restricting blade 24 arranged in pressure contact with the sleeve 22, and an electrostatic latent image on a latent image carrier is developed and transcribed on a transcribing material through the action of the single component developing toner according to the present invention, wherein the melt index at 125 deg.C is 10-40 (g/10min), the index for easiness to be crushed is 1.0-3.0, and the mean particle size by volume is 5-9μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component developing toner for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

In one-component development, a thin layer of charged toner formed on a sleeve passes through a pressure contact gap between a developing sleeve and a toner regulating blade to develop an electrostatic latent image formed on a photoreceptor. It is a method. Since the charging of the toner and the formation of the toner thin layer on the developing sleeve are performed at the pressure contact portion of the toner regulating blade as described above, the toner is stressed, and the toner is easily fixed to the toner regulating blade and the developing sleeve. .

Further, recently, from the viewpoint of energy saving, safety and easiness of design, a low temperature fixing property is required for the toner, and a toner having anti-sticking property and low temperature fixing property is also known. Is generally provided with a cleaning device for removing the residual toner on the photosensitive drum to prevent the deterioration of image quality. However, such a cleaning device causes abrasion of the photosensitive drum due to friction with the cleaning blade, and it is necessary to discard residual toner accumulated in the cleaning device.

In order to solve such a problem, Japanese Patent Laid-Open No. 62-203182 and Japanese Patent Laid-Open No. 3-797.
Japanese Patent Publication No. 2 proposes a developing device that performs development and cleaning at the same time and does not require a conventional cleaning device. However, by applying the toner as described above to this developing device, it is attempted to achieve both the sticking resistance and low-temperature fixability of the toner before passing through the sleeve, and the cleaning characteristics of the photoconductor in which cleaning is performed simultaneously with development. However, a large amount of fine powder is generated in the charge application process and the development process by the toner regulation blade, and accordingly, the transferability from the photosensitive drum to the transfer paper is deteriorated and a large amount of residual toner is generated. There is a problem that it is impossible to deal with such problems.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a one-component developing toner which has excellent anti-sticking property, low-temperature fixing property and electrostatic latent image carrier cleaning property.

[0006]

SUMMARY OF THE INVENTION The present invention is used in a one-component developing device that charges toner by passing through a gap between a developing sleeve and a toner regulating blade arranged in pressure contact with the developing sleeve. A one-component developing toner that develops an electrostatic latent image on an image carrier and transfers it to a transfer material.
Melt index value at 125 ° C (hereinafter referred to as "MI
Value ") is 10 to 40 (g / 10 minutes), the pulverizability index is 1.0 to 3.0, and the volume average particle size is 5.0 to 9.0 μm. Regarding toner.

By improving the toner, the present invention seeks to achieve both the sticking resistance and low-temperature fixability of the toner and the cleaning property of the photoconductor which does not require a conventional cleaning device. The one-component developing toner of the present invention is characterized by defining an MI value, a pulverizability index and a volume average particle diameter. The MI value is an index showing the melt viscosity of the toner at a certain specific temperature, and the pulverizability index is an index of the hardness of the toner.
Has a desired viscosity even at a relatively low temperature, is hardly destroyed at the time of stirring in a developing device, when a charge is applied by a toner regulating blade or at the time of development, and almost no fine powder is generated.
That is, it is possible to easily provide a toner having excellent sticking resistance, low-temperature fixability, and photoreceptor cleaning characteristics.

The MI value of the toner according to the present invention (g / 10
Min) is 10-40, preferably 15-35. Details are described later in the item of toner evaluation method,
The higher the value, the lower the viscosity. This value can be adjusted by selecting a toner composition such as a binder resin and an anti-offset agent contained in the toner. If this value is less than 10, the viscosity becomes high and low temperature fixability cannot be obtained. On the other hand, if it is more than 40, the viscosity becomes low and a problem arises in high temperature offset property.

Further, the toner of the present invention has a pulverizability index of 1.
It is 0 to 3.0, preferably 1.5 to 3.0. The larger this index, the harder the toner particles. This index can be adjusted by selection of the binder resin, specifically, its molecular weight and solvent-insoluble component content. If the pulverizability index is less than 1.0, the toner particles become too soft and brittle, and are easily broken, so that a large amount of fine powder is generated during stirring in the developing device or when an electric charge is applied, causing fog in the image. Photoconductor cleaning characteristics cannot be obtained. Further, the toner particles are deformed by the contact with the toner regulating blade and the like, which causes a problem of sticking to the blade or the sleeve. On the other hand, when the pulverizability index is larger than 3.0, the toner particles become too hard, the low temperature fixing does not work well, and the toner is hard to be broken, so that the productivity of the toner deteriorates.

Further, the toner of the present invention has a volume average particle diameter of 5.0 to 9.0 μm, preferably 6 to 8. 9.0μ
If it is larger than m, it does not meet the conventional purpose of high image quality, and if it is smaller than 5.0 μm, it is difficult to handle at the time of development, transfer and fixing, which adversely affects the image quality and lowers productivity and increases cost. Will be.

The binder resin used in the present invention is not particularly limited, but a resin having a softening point (Tm) of 90 to 140 ° C. is preferable from the viewpoint of securing low temperature fixability.
For example, conventionally used styrene resin, styrene-acrylic resin, polyester resin and the like can be used.

Particularly preferred in the present invention are polyester resins. Particularly in the non-magnetic one-component developing method, the toner is charged by passing through the gap between the pressure contact portion between the developing sleeve and the toner regulation blade. In this case, the toner sticking resistance to the blade or sleeve becomes a problem. From the viewpoint of properties, it is preferable to use a polyester resin. The polyester resin is synthesized from a polyol component and a dicarboxylic acid, and the polyol component contains at least an etherified diphenol, and the etherified diphenol is bisphenol A or di-
Diphenyls of (4-hydroxyphenyl) methane and ethylene oxide, propylene oxide, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene ether glycol, glycerol, trimethylolpropane, An adduct with a compound selected from the group consisting of pentaerythritol, dipentaerythritol and tripentaerythritol can be used, and as the dicarboxylic acid component, maleic acid,
Fumaric acid, mesaconinic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, malonic acid, 1,2,4-benzenetricarboxylic acid, 1,2, 5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,5-cyclohexanetricarboxylic acid,
1,2,4-butanetricarboxylic acid, 1,3-dicarboxy-
2-Methyl-2-methylcarboxypropane tetra (methylcarboxy) methane can be used. Preferred polyester resins have a Tm of 90 ° C to 140 ° C and a Tg of 60 ° C to 7 ° C.
It has an acid value (Av) of 10 to 40 KOH mg / g at 0 ° C. and a methyl ethyl ketone insoluble component content of 5 to 30 wt%. If the Tg is lower than 60 ° C, the storage stability is lowered and the toner is apt to aggregate, and if the Tg is higher than 70 ° C, the low temperature fixing property of the toner is lowered. If the Av is less than 10 KOHmg / g, the dispersibility of the colorant, the offset preventive agent, etc. will deteriorate
If it is more than 40 KOHmg / g, the moisture resistance of the toner will be problematic. When the content of the methyl ethyl ketone insoluble component is less than 5% by weight, the non-offset region becomes narrow, and when it is more than 30% by weight, the low temperature fixability is deteriorated.

In synthesizing the polyester, a plurality of types of the polyol component and the dicarboxylic acid component may be mixed and used. Further, a plurality of types of polyester may be used in combination in the toner. Further, a urethane-modified polyester resin obtained by reacting a polyester resin with an isocyanate can also be used.

The offset preventive agent used in the present invention must be appropriately selected depending on the softening point of the resin used. Generally, it is desirable to use one having a softening point of 80 to 150 ° C, preferably 85 to 145 ° C. Examples thereof include carnauba wax, sazol wax, rice wax, candelilla wax, jojoba oil wax, beeswax wax, oxidized polyethylene wax, oxidized polypropylene wax, polyethylene wax, and polypropylene wax. These may be used alone, or plural ones having different softening points may be selected and used in order to widen the non-offset region.

The amount of the anti-offset agent added is 1.0 to 5.0 parts by weight, preferably 2.0 to 4.0 parts by weight, based on 100 parts by weight of the resin. If the amount is more than 5.0 parts by weight, toner sticking may occur or the fluidity of the toner may be impaired.
If the amount is less than 0 parts by weight, offset occurs.

The colorant is not particularly limited, and the colorants conventionally used in electrophotography can be used, and the following can be exemplified. First, the black pigment as a colorant,
Carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, ferrite, magnetite and the like can be used. Examples of yellow pigments include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, bunzer yellow G, bunzer yellow 10G, benzidine yellow G, benzidine yellow GR, Quinoline yellow lake, permanent yellow NCG, tartrazine lehake, etc. can be used.

As the red pigment, there are red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK, red iron oxide, cadmium red, and red lead. , Permanent Red 4R, Resole Red, Pyrazolone Red, Watching Red, Lake Red C, Lake Red D, Brilliant Carmine 6B,
Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, Permanent Orange GTR, Vulcan Fast Orange GG, Permanent Red F4RH, Permanent Carmine FB and the like can be used. As the blue pigment, navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, and the like can be used. The colorant is added in an amount of 1 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the resin in the toner.

In the toner of the present invention, in addition to the above, a charge control agent, for example, a negatively chargeable charge control agent such as a metal-containing system or a metal-free system, a positive charge control system such as a nigrosine system or a triphenylmethane system, may be used. Agents, fluidizing agents such as silica fine particles, titanium dioxide fine particles, alumina fine particles, magnesium fluoride fine particles, and resin beads as a cleaning aid, such as Teflon, polyethylene, silicone, styrene resin, acrylic resin, etc. , Etc. may be added.

The one-component developing toner of the present invention is a known method, for example, a method in which the above materials are mixed and kneaded, and a cooled kneaded product is pulverized and classified, a suspension polymerization method, an emulsion polymerization method, an emulsion dispersion method. It can be easily obtained by a spray drying method or the like.

The toner thus obtained is applied to a developing device having a schematic structure shown in FIG. 1, for example, which performs cleaning simultaneously with development without a cleaning device. In this apparatus, a regulation blade is pressed against the surface of the toner carrier (developing sleeve) to regulate the amount of toner on the surface of the toner carrier, and the toner supplied to the surface of the toner carrier is frictionally charged. The toner is supplied from the toner carrier to the photoconductor.

In FIG. 1, the photosensitive drum 1 has a photosensitive layer formed on a conductive substrate and is rotated in the direction of the arrow in the figure. The charging brush 2 as a charging member is the photosensitive drum 1
Is provided in contact with the surface of. Then, by applying a predetermined charging voltage to the charging brush 2 by the power source 3, the surface of the photosensitive drum 1 is charged to a predetermined polarity and surface potential. An electrostatic latent image is formed on the surface of the photosensitive drum 1 charged to a predetermined potential by image exposure 4, and the electrostatic latent image is developed by the non-magnetic one-component developing device 5 to form a toner image. The details of the one-component developing device will be described later.

The transfer roller 6, which is a transfer member, has a conductive elastic layer formed on the outer periphery of a cored bar, and is pressed against the photosensitive drum 1 with a predetermined pressure to rotate in the direction of the arrow in the figure. A bias having a polarity opposite to the charge polarity of the toner is applied to the transfer roller 6 by the power supply 7. The transfer material 8 is conveyed between the photoconductor drum 1 and the transfer roller 6, and the toner image on the photoconductor drum 1 is transferred onto the transfer material 8 under application of the bias described above.

The transfer material 8 on which the toner image is transferred is
A toner image carried on a surface by being conveyed to a fixing device having a fixing roller pair 11 including a heating roller having a heater built therein and a pressure roller pressed against the heating roller, and passing between the fixing roller pair 11. Is fixed. The toner remaining on the surface of the photosensitive drum 1 after the toner image is transferred to the transfer material 8 is collected by the developing sleeve 22 of the developing device 5 in the next developing process.

The above-described one-component developing device 5 to which the toner of the present invention is applied is equipped with a drive roller 21 which is rotationally driven in the direction of the arrow in the figure by a drive means (not shown). A flexible developing sleeve 22 having an inner diameter slightly larger than the diameter is externally fitted. Both ends of the developing sleeve 22 are pressed against the driving roller 21 from the back by the pressing guides 23, while the slack portion 30 formed on the opposite side by the pressing contacts the photosensitive drum 1 flexibly. A toner regulating blade 24 is in contact with the developing sleeve 22 from the same side as the pressing guide 23.

Behind the developing sleeve 22 is the buffer chamber 2.
5, a toner supply chamber 26 is provided behind it, a toner supply rotating member 27 is arranged in the buffer chamber 25, and a toner stirring / supply rotating member 28 is arranged in the toner supply chamber 26. Further, on the lower surface of the developing sleeve 22,
A lower seal member 29 for preventing toner from leaking from the buffer chamber 25 to the outside is in contact therewith. According to this developing device, the toner supply chamber 2 is rotated by the rotation of the rotating member 28.
The non-magnetic one-component toner sent from 6 to the buffer chamber 25 is sequentially supplied to the surface of the developing sleeve 22 by the rotation of the toner supply rotating member 27.

On the other hand, the developing sleeve 22 is a driving roller 21.
Is driven to rotate by frictional force due to frictional force, and the toner supplied thereto is frictionally charged under the pressure of the blade 24 by passing between the toner regulating blade 24 and the sleeve 22 and has a predetermined thickness. It is said to be a thin layer. This thin toner layer is held on the surface of the developing sleeve 22, is transported to the developing area facing the photosensitive drum 1, and is used for developing the electrostatic latent image under the application of an appropriate developing bias. At the same time, the toner remaining on the photosensitive drum 1 is removed by the developing sleeve 22.
Recovered above. After the development, the excess toner and the collected toner remaining on the sleeve 22 are returned to the buffer chamber 25 through the intermediate seal member 29 and the developing sleeve 22 as the sleeve 22 rotates.

Although an example of the non-magnetic one-component developing device using the toner of the present invention has been described above, the present invention is not limited to this. For example, in the developing device shown in FIG. 1, the developing sleeve 22 has a larger inner diameter than the outer diameter of the driving roller 21 and has the slack portion 30, but such a slack portion is not formed. That is, a developing sleeve having an inner diameter equal to the outer diameter of the driving roller 21 can be used.

The present invention will be further described below with reference to examples.

[0029]

Example Synthesis of Polyester Resin A A 5-liter four-necked flask was equipped with a reflux condenser, a water separator,
It was equipped with a N ₂ gas introduction tube, a thermometer, and a stirrer, and was installed in a mantle heater. 1376 g of bisphenol propylene oxide adduct and 39 of isophthalic acid were added to the flask.
8 g, 113 g succinic acid, placed diethylene glycol 85 g, while introducing N ₂ gas into the flask 220-27
Dehydration polycondensation was performed at 0 ° C. to obtain polyester resin A.
The obtained polyester had the following physical properties. Glass transition point (Tg): 60 ° C, softening point (Tm): 100 ° C
Number average molecular weight (Mn): 5000, weight average molecular weight (M
w): 12000, acid value (Av): 23 KOH mg / g.

Synthesis of Polyester Resin B A 5-liter 4-necked flask was equipped with a reflux condenser, a water separator,
It was equipped with a N ₂ gas introduction tube, a thermometer, and a stirrer and installed in a mantle heater, charged with 1200 g of a bisphenol propylene oxide adduct, 110 g of neopentyl glycol and 850 g of isophthalic acid, and introduced N ₂ into the flask while introducing N _2. Dehydration polycondensation was performed at a temperature of ˜270 ° C. to obtain a low molecular weight polyester.

Next, a 5 liter four-necked flask was equipped with a reflux condenser, a water separator, a N ₂ gas inlet tube, a thermometer, and a stirrer, and installed in a mantle heater to give 1720 g of a bisphenol propylene oxide adduct. Isophthalic acid 860g, succinic acid 119g, diethylene glycol 12
9 g and 74.6 g of glycerin were charged, and dehydration polycondensation was performed at a temperature of 240 ° C. while introducing N ₂ into the flask to obtain a polyester for polymerizing.

4200 parts by weight of the low molecular weight polyester and 2800 parts by weight of the polyester for polymerizing were put into a Henschel mixer, dry blended until sufficiently uniform, and then put into a heating kneader at 120 ° C.
And diphenylmethane-4,4-diisocyanate 100
After adding 1 part by weight and reacting for 1 hour, it was confirmed by the measurement of NCO% that the remaining free isocyanate groups were almost gone, and after cooling, polyester resin B having a urethane bond (Tg = 65 ° C., Tm = 140 ° C, Av = 25
KOH mg / g, methyl ethyl ketone insoluble component content = 20
Wt%) was obtained.

(Production of Toner) Example 1 Part by Weight Polyester Resin A 50 Polyester Resin B 50 Carbon Black (Mogar L: Cabot) 5 Charge Control Agent (Bontron S-34: Orient Chemical Co.) 2 Oxidized Low Molecular Weight Polypropylene 2 (Tm: 145 ° C, Av: 3.5KOHmg / g) (Viscor TS-200: Sanyo Chemical Co., Ltd.) Carnauba wax 2 (Tm: 85 ° C, Av: 4KOHmg / g: Kato Yoko Co., Ltd.) Henschel After thoroughly mixing with a mixer, the mixture was kneaded using a twin-screw kneading extruder, and the kneaded product was allowed to cool and then coarsely pulverized using a feather mill. The coarsely pulverized product was further finely pulverized using a jet mill, and then classified by wind force to obtain toner particles having a volume average particle size of 8 μm. The toner particles 100
Part by weight and 0.8 part by weight of hydrophobic silica (Talanox 500: manufactured by Tarco Co., Ltd.) were mixed with a Henschel mixer and stirred to obtain a toner whose surface was treated with hydrophobic silica.

Example 2 10 parts by weight of polyester resin A, polyester resin B
A toner was obtained in the same manner as in Example 1 except that 90 parts by weight of was used.

Example 3 20 parts by weight of polyester resin A, polyester resin B
A toner was obtained in the same manner as in Example 1 except that 80 parts by weight of was used.

Example 4 30 parts by weight of polyester resin A, polyester resin B
A toner was obtained in the same manner as in Example 1 except that 70 parts by weight of was used.

Comparative Example 1 A toner was obtained in the same manner as in Example 1 except that 50 parts by weight of polyester resin A and 50 parts by weight of polyester resin B were replaced with 100 parts by weight of polyester resin B.

Comparative Example 2 A toner was obtained in the same manner as in Example 1 except that 50 parts by weight of polyester resin A and 50 parts by weight of polyester resin C were replaced by 80 parts by weight of polyester resin A and 20 parts by weight of polyester resin B.

Comparative Example 3 A toner was obtained in the same manner as in Example 2 except that carnauba wax was not added.

(Evaluation Method) An electrophotographic printer [SP1000 (system speed 35 mm / s); manufactured by Minolta Co., Ltd.] which was modified so that the set temperature of the fixing roller could be adjusted and which had the cleanerless structure shown in FIG. 1 was used. Then, the fixing property, fixing strength, fogging on the photoreceptor, heat resistance and non-offset area of the obtained toner were evaluated. The MI value and the pulverizability index were also measured.

[0041] Put the toner to the developing device of the sessile electrophotographic printer SP1000 (no photosensitive member), is continuously rotated for 30 hours sleeve. When toner adheres to the blade, white streaks occur on the sleeve. White stripes were evaluated as x, non-white stripes were evaluated as o, and slight stripes were evaluated as Δ.

Fixing strength The temperature of the roller is set to 140 ° C. to fix the toner image, and an area having an image density (ID) of 1.35 to 1.45 is applied with an eraser as shown in FIG. After reciprocating 3 times, the ID was measured and the fixing strength was calculated by the following formula. The fixing strength is required to be 85% or more for the portion having ID 1.2 or more. Those with 85% or more were marked with ◯, and those with less than 85% were marked with x.

[0043]

[Equation 1]

The temperature of the fog roller on the photoconductor was set to 130 ° C. to fix the toner image, and the fog on the photoconductor was observed at the initial stage and at the end of printing (3,000 sheets). ⊚: Fogging was almost absent, ∘ was slightly fogging, but there was no problem in practical use.
Those with a lot of fog were marked as x.

When 5 g of the heat-resistant toner was placed in a glass bottle and placed in an environment of 60 ° C. for 5 hours, toner aggregation occurred and the toner was not observed.

Non-offset region The roller set temperature was changed every 5 ° C. to 110 to 220 ° C. to fix the toner image, and the temperature range in which no offset occurred was determined. Non-offset area is 140 ± 20 ℃
is required.

MI value Toner MI value is measured according to JIS K-7210 A
Performed according to the law. The measurement temperature is 125 ° C. and the load is 2.169 kg.

[0048] Milling index Cryptron pulverizer (KTM-I type; manufactured by Kawasaki Heavy Industries, Ltd.) was set to an open circuit, the rotor rotational speed 9300Rpm, when the total air amount is 7.0 nm ³ / min, crushing rotor The motor load power value W ₀ [W] was recorded.

Then, a coarsely crushed product crushed by a feather mill
(Average particle size D ₀ ) Supply amount [F] 40kg by quantitative feeder
/ Hr. The load on the crushing rotor increased, and the load power value W ₁ [W] at that time was recorded. The average particle size D ₁ after crushing was measured with a Coulter counter (Nikkaki). The crushability index [K] was calculated by the following formula.

[0050]

[Equation 2]

However, when D ₀ >> D ₁ ,

(Equation 3) I asked for it.

The above results are shown in Table 1 below.

[Table 1]

The toner obtained in Comparative Example 1 had a problem in low-temperature fixability. Since the MI value of this toner is low, it is considered that this is because the viscosity at the time of fixing is high and it is difficult for the toner to flow. Further, since the offset is often generated, the fixing strength cannot be measured. The toner obtained in Comparative Example 2 caused a large amount of fog on the photoconductor and was not excellent in sticking resistance. Since this toner has a low pulverizability index, it is soft and brittle, and it is considered that this is because a large amount of fine powder was generated during development or charge application, and it can be said that the toner has also poor photoreceptor cleaning properties. Since the toner obtained in Comparative Example 3 had a large amount of offset at low temperature fixing, the fixing strength could not be measured.

[0054]

The toner of the present invention is a toner for one-component development, which is excellent not only in heat resistance but also in sticking resistance, low-temperature fixability, and electrostatic latent image bearing member cleaning property. The non-offset area is also good.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a one-component developing device.

FIG. 2 is a diagram for explaining a method of measuring fixing strength.

[Explanation of symbols]

1: photoconductor drum, 2: charging brush, 3: power supply, 4: exposure, 5: one-component developing device, 6: transfer roller, 7: power supply,
8: transfer material, 11: fixing roller pair, 21: drive roller,
22: developing sleeve, 23: pressing guide, 24: toner regulating blade, 25: buffer chamber, 26: toner supply chamber, 27: toner supply rotating member, 28: toner stirring / supply rotating member, 29: lower seal member, 30 : Slack part

Claims (2)

[Claims] 1. A one-component developing device for charging toner by passing through a gap between a developing sleeve and a toner regulating blade arranged in pressure contact with the developing sleeve. A one-component developing toner for developing an image and transferring it to a transfer material, having a melt index value at 125 ° C. of 10 to 40 (g / 10 minutes), a pulverization index of 1.0 to 3.0, and a volume. A one-component developing toner having an average particle diameter of 5.0 to 9.0 μm. 2. The one-component developing toner according to claim 1, wherein the one-component developing toner is used in an image forming apparatus in which the toner remaining on the surface of the electrostatic latent image carrier after transfer is collected by the one-component developing apparatus.