JPH1172948A - Toner for developing electrostatic images - Google Patents

Abstract

(57) Abstract: An object of the present invention is to solve the above-mentioned problems in a toner for pulverizing and classifying a kneaded material. An object of the present invention is to provide a toner which has a good rise and good replenishing properties, developing properties and transfer properties. SOLUTION: A dry toner obtained by pulverizing a kneaded product comprising a binder resin, a charge control agent, a colorant, and a fixing aid has a circularity of 0.97 or more and less than 1.00, and a bulk density of Is 0.3 g / cm ³ or more, and the outflow starting temperature is 95 ° C. or less. (Here, circularity = average circularity + 0.0049 × volume average particle diameter−0.0091 × D90 / D10)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In a system for developing an electrostatic image, a fine powder developer called a toner in which a polarity control agent and a colorant are dispersed and contained in a natural or synthetic resin such as a cascade method or a magnetic brush method is used. There is an electrostatic development method. In recent years, with the development of digital copiers and laser printers,
There are many demands for so-called high image quality. In particular, 300 dpi is the mainstream such as a printer, and 600 dpi and 800 dpi are expected in the future, and high image quality is the mainstream.
For this reason, it is possible to reduce the particle size of the toner.

However, a reduction in the particle size of the toner tends to cause aggregation and adhesion of the toner particles.
The phenomenon in which the toner in the replenishing unit is difficult to replenish to the developing unit and the image density is reduced, so-called poor replenishment, the phenomenon in which the image density is difficult to develop from the developing unit to the photoconductor, the so-called poor developing,
A phenomenon that image transfer is difficult to transfer from the photoconductor, that is, a phenomenon in which image density decreases, that is, a so-called transfer failure is likely to occur. These are all caused by an increase in the cohesiveness and adhesion of the toner particles due to the reduction in the particle size of the toner. When the particle size is reduced, the specific surface area of the toner increases, the cohesiveness and the adhesiveness deteriorate, and the fluidity decreases. If the cohesiveness is high (poor), the toner is unevenly distributed at the time of development and charging with the carrier, and the frictional charging of the toner carrier is not sufficiently generated. A reduction in volume occurs. Particularly, in order to reduce the fixing energy of an image after development, when a resin having a low melting point is used, or when a fixing auxiliary agent is contained, a toner for a fixing system in which a toner fixing prevention oil is not applied to a fixing roll, so-called, In the case of an oilless toner, the tendency is particularly strong.

[0004] When such a variation in charge and a decrease in charge amount occur, toner particles having a low charge amount are easily developed on a non-image portion, resulting in generation of background stain. It is difficult to develop in the image area, and the image density is reduced. If the fluidity is poor (low), toner replenishment failure will occur, the amount of development in the developing unit will decrease, and the image density will decrease. In addition, poor adhesion results in strong adhesion between the toner and the photoreceptor part, resulting in a large residual amount of the photoreceptor part and a small transfer amount on transfer paper during transfer, resulting in poor image density and image density. White spots occur in the image. Such deterioration of the cohesiveness, adhesion and fluidity becomes more remarkable as the particle size of the toner becomes smaller. To address these issues,
It has been studied from the aspect of the toner shape and the manufacturing method.
From a manufacturing method, a method of attaching an additive to a surface of a toner is generally known. Also, from the toner shape side,
A device that defines a toner shape value is known.

[0005] Among the techniques relating to the toner shape, Japanese Patent Application Laid-Open Nos. 60-117252 to 60-1172 relate to examples of producing a polymerized toner and a spherical toner.
No. 55 discloses that a magnetic polymerized toner having a practical sphericity (image analysis by Luzex) of 0.95 to 1.0 and a charge amount of carbon black or resin is specified so that the toner is free from dust, dust, fog, and high image quality. Density, fixability,
It describes that transferability and environmental properties are improved, and JP-A-60-121455-JP-A-60-1214.
No. 57 discloses that the practical sphericity of Wardell (image analysis by Luzex) is 0.95 to 1.0 and the fixing properties of the polymerized toner are determined by defining the types of the wax and the magnetic substance.
It is described that the offset property and the image density are improved, and JP-A-3-84558 discloses that the circularity (minor axis / major axis ratio) is set at 0. 0 for the purpose of improving resolution and durability. Spray granulation and polymerization toners of 95 to 1.0 are described. Japanese Patent Application Laid-Open No. 3-229268 discloses an improvement in moisture resistance by setting the sphericity (ratio of minor axis / major axis) ≧ 0.7. JP-A-3-2481 discloses a polymerized toner which has been attempted.
Japanese Patent Application Laid-Open No. Hei 4-62 discloses that by setting the BET specific surface area / the Coulter specific surface area before adding the additives to 3.0, the chargeability and cleaning property of the polymerized toner are improved. No. 1766, JP-A-4-176
No. 7 discloses that the circumscribed circle inscribed circle ratio is 1.0 to 1.2 and the peripheral length inscribed circle ratio is 1.01 to 2.0. Japanese Patent Laid-Open Publication No. HEI 4-10286 describes that
No. 2, JP-A-4-102863 and JP-A-4-102864 disclose sphericity (minor axis / major axis ratio).
It is disclosed that image reproducibility is improved by using a polymerized color toner of ≧ 0.8.

Japanese Patent Application Laid-Open Nos. 2-87157 and 2-146557 disclose a method for producing a spherical toner which includes a spherical toner treatment for pulverized toner. Specific surface area) is 0.4 to 0.8, and the surface ratio of polyolefin is 10 to 4
Japanese Patent Application Laid-Open No. 63-244052 describes that transfer is improved by using a magnetic toner containing a specific magnetic substance at 0% and crushing a pulverized toner by mechanical impact into a spherical shape.
Heat treatment, low pressure jet mill, impact type pulverizer, etc., after grinding and classification, with a minor axis / major axis ratio of 0.7-0.9, control the surface condition of toner, and achieve high image quality. It is described in Japanese Patent Application Laid-Open No.
Japanese Patent No. 102861 discloses a toner in which the shape factor (peripheral length 2 / 4π projected area) of the most frequent particles is 1.05 to 1.30, the number average particle diameter is 3 to 15 μm, and the pulverized toner is made spherical by hot air or attrition. And that the cleaning property is improved by a polymerized toner.
No. 35953-JP-A-63-235596,
Japanese Patent Application Laid-Open No. 2-85865 discloses that the pulverized toner is made spherical by repetition of mechanical impact, with a circularity (perimeter of a circle of the same area / perimeter of a projection surface) of 2 = 0.7 to 0.8. Magnetic toner or specific polyester toner or fixability improver (W
AX etc.) containing toner or non-magnetic one-component toner improve the developing property and the cleaning property.

Many of the shapes described in patent documents are spherical toners produced by a polymerization method or a solution dissolution method.
Since it is significantly different from the current production equipment (kneading, pulverization, classification), new equipment is required. In addition, although the toner manufactured by the polymerization method or the solution dissolution method is a true sphere, the cohesiveness, the adhesiveness, and the cohesiveness, the adhesiveness,
In order to improve the fluidity, even if it is not a true sphere, a toner with an irregular shape, no sharp corners, and a slightly smooth surface is sufficient, so new equipment that is significantly different from current manufacturing equipment is unnecessary. is there.

[0008] Further, when mechanical shock is repeated or spheroidized by heat using the current manufacturing equipment, that is, equipment having kneading, pulverizing, and classifying, the toner surface composition changes due to heat. In particular, in the case of a toner containing a low-melting resin for reducing the fixing energy or a fixing aid for an oilless system, the amount of the fixing aid on the surface increases due to the melting of the fixing aid by heat, Charging and cohesiveness change greatly. In particular, the tendency is remarkable in a toner having an outflow start temperature of 95 ° C. or lower.

By the way, what represents the shape of the toner includes:
There are the following: -Minor length = minor axis / major axis (or major axis / minor axis)-Circularity = (perimeter of a circle having the same area as the projected area of the particle / length of the contour of the projected particle image)-Shape factor = perimeter of the particle 2 / 4π projected area ・ Wadell's true sphericity = surface area of a sphere (equal volume sphere) having the same volume as the actual particle / surface area of the actual particle ・ Wadell's practical sphericity = an area equal to the projected area of the particle The diameter of the circle / the diameter of the smallest circle circumscribing the projected image of the particle.
Approach. However, even in the same shape, the influence of the particle size is also observed, and it is known that the smaller the particle size, the closer to 1.0, and it is difficult to evaluate unless the influence of the particle size is removed.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in a toner for pulverizing and classifying a kneaded material. Even a toner having a small particle size has good cohesiveness, fluidity and adhesion, and has a small charge rise. It is an object of the present invention to provide a toner which has good replenishability, developability and transferability.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that even a low-melting-point resin and a toner having a small particle diameter have cohesive properties.
Finding toner characteristics that have good fluidity and adhesion, good charge rise, good replenishment, developability, and transferability, and a preferable shape when this toner shape is numerically displayed using a circularity measurement method. Value was found. That is, the present invention provides a dry toner obtained by pulverizing a kneaded product comprising a binder resin, a charge control agent, a colorant, and a release agent, having a circularity of 0.97 or more, less than 1.00, and a bulkiness of A toner characterized by having a density of 0.3 g / cm ³ or more and an outflow start temperature of 95 ° C. or less (where circularity = average circularity + 0.0049 × volume average particle diameter−0.0091 × D9)
0 / D10)), and such a toner can provide an image with good transferability and high quality. The circularity was determined by measuring using a flow type particle image analyzer manufactured by Toa Medical Electronics Co., Ltd. The circularity measurement obtained from the measurement using the flow type particle image analyzer is performed as follows. A measurement sample is dispersed in a liquid, a still image of particles is photographed, image analysis is performed, and individual circularity is calculated from a projected area and a peripheral length of the particle image, and an average circularity is obtained.

[0012]

(Equation 1) Further, the apparatus can measure the volume average diameter, the volume integrated 10% particle diameter (D10), and the volume integrated 90% particle diameter (D90) by image analysis. As a result of the multiple regression analysis, circularity = average circularity + 0.0049 × volume average particle size−0.0
091 × D90 / D10 was obtained. Even if the particle diameter of the toner changes, this circularity is the same if the toner shape is the same.
The values have the same circularity. The higher the value, the smoother the surface with no sharp corners in the irregular shape. In the case of a normal pulverized toner, the external surface shape factor is 0.95. When the circularity is 0.97 or more, the toner surface becomes smooth, so that the fluidity and the cohesion of the toner become good,
The image density is increased by improving the toner replenishing property, developing property, and transferring property. Further, the chargeability is also improved by the improvement of the fluidity of the toner, and the background stain (stain of the non-image portion) is reduced.

However, when the circularity is 1.00 or more, the fluidity of the toner is so good that cleaning of the transfer residual toner on the photoreceptor is deteriorated. On the other hand, when the circularity is less than 0.97, the fluidity and cohesiveness of the toner are deteriorated, the toner replenishing property, the developing property and the transfer property are reduced, and the image density is reduced and the background stain is increased.

If the toner is subjected to spheroidizing treatment such as mechanical impact or heat treatment in order to produce a toner having a circularity of 0.97 or more and less than 1.00, the effect of containing a fixing aid will appear. For toner whose outflow start temperature is 95 ° C. or less,
If too much heat is applied to the surface, the fixing aid inside the toner melts out, and conversely, the fluidity and cohesion deteriorate, and the toner replenishment, developability and transferability decrease, image density decreases, and the background decreases. An increase in soiling occurs. Therefore, in a toner containing a fixing aid and having an outflow start temperature of 95 ° C. or less, if the spheroidizing treatment is performed so that the bulk density is 0.3 g / cm ³ or more, which is a characteristic representing fluidity, The effect of spheroidization can be sufficiently exhibited without deteriorating the fluidity and the cohesiveness under the influence of the fixing aid. However, when the bulk density is less than 0.3 g / cm ³ , since the fixing aid inside the toner is melted, the fluidity and the cohesiveness are deteriorated, and the effect of spheroidization cannot be sufficiently exhibited.

When the volume average particle diameter of the insoluble portion of the toner dissolved in a binder resin-soluble solvent is 0.30 μm or less, each material is well dispersed, and the chargeability of the toner is reduced. As a result, the cohesion is improved, and the toner developability and transferability are improved, so that the image density is increased and the background smear is reduced. When the volume average particle size of the insoluble portion is larger than 0.30 μm, the respective materials are not dispersed, and the chargeability and the cohesiveness of the toner are deteriorated. It tends to be low, and the background dirt tends to increase.

The volume average particle size of the insoluble portion was determined by a centrifugal sedimentation type particle size distribution analyzer manufactured by Shimadzu Corporation. For the measurement, an appropriate amount of toner is put into a solvent and dissolved well by an ultrasonic cleaner or the like. This solution is further diluted with the same solvent,
Measure according to the measurable concentration of the centrifugal sedimentation type particle size distribution analyzer. The measured particle size range varies depending on the specific gravity of the toner and solvent used for the measurement, but can be measured from 3 μm to 0.04 μm. The solvent used for the measurement may be a general solvent.

When the volume resistivity of the toner is low,
The conductivity is improved, and electrification hardly occurs. If the volume resistivity of the toner is 9.8 log Ωcm or more, the toner is easily charged. However, if the volume resistivity is less than 9.8 log Ωcm, charging becomes difficult, and charging characteristics become unstable,
It becomes difficult to develop, and the image density decreases and the background smear increases. The specific volume resistance is obtained by inserting a toner into a stainless steel cell and compressing it under pressure to form a pellet. An electrode plate is placed above and below the pellet, and the resistance is measured.

The standard charge amount (standard charge amount) of the toner is a charge amount at a saturated charge amount or a stirring time (standard stirring time) at which 80% or more of the saturated charge amount is achieved.
The charge amount is measured by charging a toner and a carrier into a cylindrical container such as a ball mill, stirring, and measuring with a blow-off device. Further, if the toner is easily charged and the charge rise is good, even if new toner is replenished during copying, the toner is quickly charged, so that there is no problem with image density and background contamination. Good charging rise is 1/1 of stirring time to obtain standard charge amount.
Ratio of the charge amount at the stirring time of 0 to the standard charge amount ((the charge amount at the stirring time of 1/10 of the stirring time to obtain the standard charge amount)
/ Standard charge amount). This ratio is 0.7
With the above, the charging rise is good, and at the time of toner supply,
Background dirt is improved. If this ratio is less than 0.7, background contamination is likely to occur during toner replenishment.

Further, the ratio of the charge amount when the toner stirring time is 1/40 of the standard stirring time to the standard charge amount ((the charge amount when the stirring time is 1/40 of the standard stirring time) ) / Standard charge amount), the dispersibility of the toner in the carrier can be seen. When the ratio is 0.4 or more, the toner is well dispersed in the carrier, and large black spots and background stain due to toner aggregation do not occur. If this ratio is less than 0.4, large black spots and background stain due to toner aggregation are likely to occur.

The ratio of the charge amount of the toner with the stirring time of three times the standard stirring time to the standard charge amount ((the charge amount of the stirring time of the stirring time three times the standard stirring time) / the standard charge time) If the amount) is 0.8 or more, the developer life is long because the charge does not decrease even after long-time stirring in a copying machine. When the ratio is less than 0.8, the charge is reduced by stirring for a long time, and the life of the developer tends to be shortened.

The volume average particle diameter of the toner is 5 to 20 μm.
m is desirable. If it is 5 to 20 μm, the reproducibility of the fine image line is good. The particle size distribution of the toner is expressed by volume average particle size / number average particle size. When the ratio is 1.3 or less, the narrower the distribution width, the better the reproducibility of the image fine line and one dot. Since the charge amount of the fine powder of the toner is high, when the ratio is larger than 1.3, the charge variation is large, and the background stain is easily generated.

As the binder resin used in the toner obtained by the present invention, all known resins can be used. For example, polystyrene, poly-p-styrene, homopolymers of styrene such as polyvinyltoluene and substituted products thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene -Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic Acid butyl copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer,
Styrene-maleic acid ester copolymer, styrene-based copolymer such as polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, Rosin, modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin and the like can be used alone or in combination. In these resins, if the resin Tg is 60 ° C. or more, when the pulverization and the spheroidization treatment are performed, fusion due to heat generated by collision between toner particles or between the toner and the pulverization collision portion can be suppressed,
Easy to spherical processing.

As the fixing aid, all known ones can be used as a mixture. For example, polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish and the like can be used.

As the colorant, those known for toners can be used. For example, as a black colorant, carbon black, aniline black, furnace black, lamp black and the like can be used. As the cyan coloring agent, for example, phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, ultramarine blue and the like can be used. As the magenta colorant, for example, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake, and the like can be used. As the yellow colorant, for example, chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, tartrazine and the like can be used.

Further, as these toners, in order to give more efficient charging, a known toner such as a charge control agent can be used. Examples of charge control agents include nigrosine, basic dyes, lake dyes of basic dyes, metal chains of monoazo dyes, nitrohumic acid and salts thereof, salicylic acid, dicarboxylic acid, Co, C
Metal chains such as r and Fe; organic dyes;

Of these toners, the toner having a surface charge control agent amount of 7.5E-4 g / cm ² or more per unit surface area has stable charging characteristics and provides a high quality image. The amount of the surface charge control agent per unit surface area is 7.5E-4g /
If it is less than cm ² , both the charge amount and the charge rise amount tend to be low. The amount of the surface charge control agent is such that the charge control agent dissolves, but the resin and other materials are charged with the toner in an insoluble solvent. After stirring, the solution is filtered, and the concentration of the filtrate is measured with a spectrophotometer. . When the charge control agent concentration is determined by a spectrophotometer, the measured value is compared with a separately prepared solution concentration of a dye and a solvent alone to calculate the charge control agent amount in the toner.

Further, by mixing the inorganic or organic additive with the toner, the fluidity of the toner is improved, and the replenishment from the toner-filled container to the copying machine main body is improved. The toner produced in the present invention is, if necessary, a commonly used toner additive, for example, a fluidizing agent such as colloidal silica, titanium oxide, metal oxides such as aluminum oxide, An abrasive such as silicon carbide and a lubricant such as an aliphatic metal salt may be contained. As a method for mixing the additives with the toner, a conventionally known method may be used, and the additives can be mixed with a device such as a Henschel mixer or a speed kneader.

By mixing the toner thus obtained with a carrier, an electrophotographic developer having good charging characteristics can be obtained. As the amount of the carrier and the toner of the present invention,
The toner particles adhere to the carrier surface of the carrier particles,
It is preferable to mix both particles so as to occupy 30 to 90% of the surface area. As the carrier, conventionally known carriers may be used, and non-coated carriers such as ferrite, carriers coated with styrene-acrylic resin, silicon resin, fluorine-modified acrylic resin, and the like, and granulated carriers can be used.

The toner produced according to the present invention contains a magnetic material and can be used as a magnetic toner. Known magnetic materials can be used, such as iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; or aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, and beryllium. , Bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and alloys of metals such as vanadium and mixtures thereof.

The toner of the present invention is mixed with a binder resin, a colorant, a charge control agent, and a fixing aid, and then kneaded, and the obtained kneaded material is pulverized. A toner having an irregular shape, no sharp edges, and a slightly smooth surface can be produced by a method of giving friction, abrasion, heat, impact after pulverization or at the time of pulverization. It can also be prepared by adjusting the pulverizing pressure of an air-flow type pulverizer.

[0031]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. <Example> Polyester resin 100 parts by weight Carbon black 10 parts by weight Polypropylene 5 parts by weight Quaternary ammonium salt 2 to 2.3 parts by weight The mixture having the above composition was melt-kneaded and cooled to obtain a kneaded product.
This was subjected to a spheroidizing treatment for abrasion between the pulverized portion and the toner during pulverization, and classified to obtain a toner having an average particle size of 8.0 μm.
(See Table 1) <Comparative Example> A mixture having the above composition was melt-kneaded and cooled to obtain a kneaded product. This was pulverized and classified to obtain an average particle size of 8.0 μm.
m was obtained. (See Table 1) <Test Method> The above toner was manufactured by Ricoh IMAG
It was set in a modified IO-320 digital copier, and the durability of 30,000 sheets was evaluated for image density, background stain, and charge amount. The image density and background stain (non-image density) were measured using a Macbeth densitometer, and the charge amount was measured using a blower. <Results> These results are shown in Table 2.

Example 1 Outflow starting temperature is 95 ° C. or less, circularity is 0.97 or more,
The toner of Example 1 having a bulk density of less than 1.00 and a bulk density of 0.3 g / cm ³ or more has a background stain of 0.07 or less, an image density of 1.35 or more, and a circular shape in both the initial image and the copied image. Degree less than 0.97, 1.00 or more, high density 0.3g
/ Cm ³ , which was better than Comparative Examples 1 to 3.

Example 2 A toner having a charge control agent amount larger than that of Example 1 and a surface charge control agent amount per unit surface area of 7.5E-4 g / cm ² or more was used for both the initial image and the copied image. Dirt is 0.0
7, the image density was 1.40 or more, which was better than that of Example 1.

Example 3 A toner having a volume average particle diameter of 0.3 μm or less for the insoluble portion when the toner was dissolved in a binder resin-soluble solvent by reducing the kneading treatment amount from that of Example 1 The background smear was 0.07 or less and the image density was 1.40 or more in both the initial image and the copied image.

Example 4 A toner having a volume specific resistance of 9.8 log Ωcm or more with a kneading treatment amount per hour lower than that of Example 1 is as follows.
Both the initial image and the copied image have a background stain of 0.07 or less,
The image density was 1.40 or more, which was better than Example 1.

Example 5 The circularity was made higher than in Example 1, and the ratio of the charge amount during the stirring time of 1/10 of the stirring time for obtaining the standard charge amount of the toner to the standard charge amount ((the standard charge amount was obtained). The toner whose charge amount (standard charge amount) / standard charge amount at a stirring time of 1/10 of the stirring time is 0.7 or more has a background stain of 0.1 for both the initial image and the copied image.
07 or less, and the image density was 1.40 or more, which was better than Example 1.

Example 6 The circularity was made higher than that of Example 1, and the ratio of the charge amount to the standard charge amount when the toner stirring time was 1/40 of the standard stirring time ((the stirring time was the standard stirring time) The toner whose charge amount / standard charge amount at a stirring time of 1/40 of the above was 0.4 or more had a background stain of 0.07 for both the initial image and the copied image.
Hereinafter, the image density was 1.40 or more, which was better than that of Example 1.

Example 7 The circularity was made higher than that in Example 1, and the ratio of the charge amount when the stirring time of the toner was three times the standard stirring time to the standard charge amount ((the stirring time was 3 times the standard stirring time) The toner whose charge amount / standard charge amount) was 0.8 or more in the double stirring time had a background stain of 0.07 or less and an image density of 1.40 or more in both the initial image and the copied image. It was better than No. 1.

Example 8 The toner having a ratio of volume average particle diameter / number average particle diameter of 1.3 or less has a background stain of 0.0 for both the initial image and the copied image.
7, the image density was 1.40 or more, which was better than that of Example 1.

Example 9 A toner using a polyester resin having a resin Tg of 60 ° C. or higher has a higher external surface shape factor than that of Example 1, and both the initial image and the copied image have a background smear of 0.07 or less. The concentration was 1.40 or more, which was better than that of Example 1.

[0041]

[Table 1] Charging: Charge amount for 20 min stirring Charging: Charging amount for 2 min stirring Charging: 0.5 min charging amount for stirring Charging: 60 min charging amount for stirring

[0042]

[Table 2]

[0043]

As is apparent from the detailed and specific explanations above, in the present invention, the use of the above specific toner improves the cohesiveness of the toner, improves the toner replenishment, An extremely excellent effect of improving developability and transferability, obtaining a toner having a high image density and a small amount of background stain can be obtained.

Continuation of front page (72) Inventor Tomiaki Ito 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (9)

[Claims] 1. A dry toner obtained by pulverizing a kneaded product comprising a binder resin, a charge control agent, a colorant and a fixing aid, has a circularity of 0.97 or more and less than 1.00, and A toner having a density of 0.3 g / cm ³ or more and an outflow start temperature of 95 ° C. or less. (Here, circularity = average circularity + 0.0049 × volume average particle diameter−0.0091 × D90 / D10) 2. The toner according to claim 1, wherein the amount of the surface charge control agent per unit surface area is 7.5E-4 g / cm ² or more. 3. The toner according to claim 1, wherein the volume average particle diameter of an insoluble portion of the toner when the toner is dissolved in a binder resin-soluble solvent is 0.30 μm or less. 4. The toner has a volume resistivity of 9.8 log Ω.
The toner according to claim 1, wherein the toner particle size is not less than cm. 5. A stirring time for obtaining a standard charge amount of the toner.
The ratio of the charge amount at the stirring time of / 10 to the standard charge amount ((the charge amount at the stirring time of 1/10 of the stirring time to obtain the standard charge amount) / the standard charge amount) is 0.7 or more. The toner according to claim 1, wherein: 6. The stirring time of the toner is 1/1 of the standard stirring time.
Ratio of the charge amount at the stirring time of 40 to the standard charge amount ((the charge amount at the stirring time of 1/40 of the standard stirring time)
2. The toner according to claim 1, wherein (/ standard charge amount) is 0.4 or more. 7. The ratio of the charge amount of the toner with the stirring time of three times the standard stirring time to the standard charge amount ((the charge amount of the stirring time with the stirring time of three times the standard stirring time) / standard charging) 2. The toner according to claim 1, wherein (amount) is 0.8 or more. 8. The ratio of volume average particle diameter / number average particle diameter is 1.
The toner according to claim 1, wherein the number is 3 or less. 9. The toner according to claim 1, wherein the resin Tg is 60 ° C. or higher.