JP2006227431A - Electrostatic charge image developing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner by which high color developability and sufficient color reproducibility particularly in secondary color are obtainable, and also to provide a method for manufacturing the toner and an image forming method using the toner. <P>SOLUTION: The electrostatic charge image developing toner containing a binder resin and a pigment, wherein the number average particle diameter (h=(x+y)/2) calculated from the number average major diameter (x) and number average minor diameter (y) of the pigment in the toner is ≥0.01 μm, and <0.05 μm, and the method for manufacturing the toner and the image forming method using the toner are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner for developing an electrostatic image that is suitably used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, a manufacturing method thereof, and an image formation using the toner Regarding the method.

  In recent years, high-quality and high-definition images in full color have been demanded, and high transparency and vivid color reproducibility can be mentioned as performance required for toner. In order to solve these requirements, dispersibility control of internal additives such as pigments and waxes is performed.

  Patent Document 1 calculates from the average major axis (l) and average minor axis (w) of magenta and cyan color materials in order to obtain excellent colorability, saturation, surface gloss, transparency, and concealment. An electrophotographic full-color toner having h = (l + w) / 2 of 0.05 to 0.11 μm is disclosed, and further, it is disclosed that the image density cannot be increased when the average diameter h is less than 0.05 μm.

  In Patent Document 2, in order to obtain sufficient hue, transparency, and color reproducibility, a resin is kneaded with an extruder using a quinacridone pigment having an average primary particle size of 0.01 to 0.09 μm, and then pulverized and classified. A magenta toner for charge development is disclosed.

In Patent Document 3, a master batch in which a pigment is melt-mixed in a binder resin in advance is used in order to control the dispersibility of the charge control agent and the wax, and the master batch is referred to as a binder resin. A method for producing a toner that is melt kneaded with a mixture such as a charge control agent using an open roll continuous kneader is disclosed.
JP-A-6-250444 (Claim 1, paragraph 0006) JP-A-4-342265 (Claim 1) JP 2001-75307 (paragraph 0003)

  An object of the present invention is to provide a toner capable of obtaining high color developability and particularly sufficient color reproducibility in a secondary color, a method for producing the toner, and an image forming method using the toner.

  The present invention relates to an electrostatic charge image developing toner containing a binder resin and a pigment, wherein the number average particle size (x) calculated from the number average major axis (x) and the number average minor axis (y) of the pigment in the toner ( The present invention relates to an electrostatic charge image developing toner wherein h = (x + y) / 2) is 0.01 μm or more and less than 0.05 μm.

  The present invention also relates to a method for producing an electrostatic image developing toner and an image forming method using the electrostatic image developing toner.

  With the toner of the present invention, high color developability and particularly sufficient color reproducibility can be obtained for secondary colors. Further, the toner production method of the present invention provides a toner having high color developability and particularly sufficient color reproducibility in the secondary color. Furthermore, the image forming method using the toner of the present invention can provide a good image density even if the amount of toner is small.

  Generally, a toner having an average particle diameter of pigment in the toner of about 0.1 to 0.5 μm is used. The pigment as the raw material also has an average particle size of about 0.05 to 0.2 μm. The reason why a toner having a smaller particle diameter of the pigment in the toner is generally not used is that, as described in Patent Document 1, if the average particle diameter of the pigment in the toner is less than 0.05 μm, the image density cannot be increased. It is thought that it was because it was thought. Even if a toner is manufactured using a pigment having a small particle size, it is estimated that the pigment aggregates in the manufacturing process and a pigment having a large particle size is contained in the toner, and as a result, a beneficial effect is obtained. It is thought that there is not. The toner described in Patent Document 2 uses a pigment having an average primary particle size of 0.01 to 0.09 μm. Here, a styrene-acrylic acid copolymer and a pigment are kneaded by an extruder. As a result, pigment aggregation occurs during kneading, and the average particle size of the pigment in the obtained toner is estimated to be 0.05 μm or more.

  The inventor pays attention to the phenomenon of pigment aggregation in the toner production process, and uniformly disperses the pigment having a smaller average particle diameter than that generally used in the toner without aggregation during the production of the toner. The present inventors have found that high color developability and color reproducibility that are not conventionally obtained can be obtained.

    The toner for developing an electrostatic charge image of the present invention contains a binder resin and a pigment, and the number average particle diameter (h = (h = ()) calculated from the number average major axis (x) and the number average minor axis (y) of the pigment in the toner. x + y) / 2) is 0.01 μm or more and less than 0.05 μm. By making the number average particle diameter 0.01 μm or more and less than 0.05 μm, the effects of high color development and color reproducibility are remarkably exhibited. The number average major axis and the number average minor axis of the pigment in the toner are determined by an image analysis method using a transmission electron microscope under the conditions described in the examples.

  Examples of the binder resin according to the present invention include polyester, styrene-acrylic resin, a mixed resin of polyester and styrene-acrylic resin, a hybrid resin having two or more kinds of resin components, and the like. From this point of view, it is preferable to use polyester as a main component.

  The content of the polyester in the binder resin is preferably 50 to 100% by weight, and more preferably 70 to 100% by weight. The hybrid resin is preferably a resin in which a condensation polymerization resin such as polyester, polyester / polyamide, polyamide or the like and an addition polymerization resin such as vinyl polymerization resin are partially chemically bonded. Two or more kinds of resins are used as raw materials. In order to obtain a hybrid resin efficiently, two or more kinds of resins may be obtained. What was obtained from the mixture of the raw material monomer of resin is preferable.

  The raw material monomer of the polyester is not particularly limited, and a known alcohol component and a known carboxylic acid component such as carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.

  Alcohol components include bisphenol A alkylene such as polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane. (2 to 3 carbon atoms) oxide (average added mole number 1 to 16) adduct, ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or alkylene thereof (2 carbon atoms) -4) Oxide (average added mole number 1-16) adduct and the like.

  The carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, adipic acid and succinic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octenyl succinic acid, or carbon. Trivalent or higher polyvalent carboxylic acids such as succinic acid, trimellitic acid and pyromellitic acid substituted with alkenyl groups having 2 to 20 carbon atoms, anhydrides of these acids and alkyls of these acids (1 to 3 carbon atoms) ) Esters and the like.

  The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst.

  The softening point of the polyester is preferably 80 to 165 ° C, the glass transition point is preferably 50 to 85 ° C, and the acid value is preferably 5 to 40 mgKOH / g. The desired softening point and acid value can be obtained by adjusting the condensation polymerization temperature and reaction time.

  Examples of the pigment according to the present invention include yellow pigments, magenta pigments, and cyan pigments. These pigments may be used alone or in combination of two or more. Specific examples of yellow pigments include pigment yellow 17, pigment yellow 74, pigment yellow 180, pigment yellow 151, pigment yellow 155, pigment yellow 154, pigment yellow 185, pigment yellow 139, and pigment yellow 167. Examples of magenta pigments include carmine 6B, quinacridone, pigment red 146, and pigment red 238. Examples of cyan pigments include pigment blue 15: 3, pigment blue 15: 1, pigment blue 16, and aluminum phthalocyanine. The number average particle diameter (h = (x + y) / 2) calculated from the number average major axis (x) and the number average minor axis (y) of the pigment in the toner is 0.01 μm or more and 0.05 from the viewpoint of color development and color reproducibility. It is less than μm, more preferably 0.01 to 0.048 μm.

  Further, from the viewpoint of little pigment aggregation and influence on color developability, the pigment having an area particle diameter of 0.22 μm or more is preferably 5 area% or less, particularly preferably 3 area% or less. The area particle diameter of the pigment in the toner is determined by an image analysis method using a transmission electron microscope under the conditions described in the examples.

  The toner of the present invention can be obtained by a production method having the following steps (1) to (3). Step (1): A pigment having a number average particle diameter (h = (x + y) / 2) calculated from the number average major axis (x) and the number average minor axis (y) of 0.01 μm or more and less than 0.05 μm is dried. A step of kneading together with the binder resin (A) without passing through a step to obtain a pigment dispersion, step (2): a step of kneading the pigment dispersion with the binder resin (B) to obtain a kneaded product, and Step (3): Step of pulverizing and classifying the kneaded product

  Step (1) is a step in which a pigment having a number average particle size of 0.01 μm or more and less than 0.05 μm is kneaded with the binder resin (A) without passing through a drying step to obtain a pigment dispersion. Such a dispersion facilitates sufficient dispersion without aggregation of the pigment in the toner in the step (2). As the binder resin (A), those mentioned for the binder resin can be used.

  The pigment used in the toner production method of the present invention has a number average particle size of 0.01 μm or more and less than 0.05 μm, particularly preferably 0.02 to 0.04 μm. The pigment concentration in the dispersion is preferably 10 to 70% by weight, particularly preferably 20 to 50% by weight.

  Further, a salt milled method may be used as a method for obtaining a pigment having a primary particle size of 0.01 μm or more and less than 0.05 μm. Salt milled pigments are preferred in that they have few coarse particles and are small particles with a uniform particle size. A pigment dispersion can be obtained by using a wet cake obtained by filtering the salt milled pigment. For example, the synthesized pigment crude is subjected to salt milling with a binder such as ethylene glycol and a grinding agent such as sodium chloride, washed with water, and filtered to obtain a wet cake. ) And kneading. Since it is kneaded in the binder resin without going through the pigment drying step, it is preferable in that it does not easily generate pigment aggregates. The moisture content of the wet cake is preferably 50 to 70% by weight in the wet cake.

  As a method for kneading the pigment dispersion, a pigment wet cake is kneaded together with the binder resin (A) using a manufacturing apparatus such as a kneader or a heated roll mill to remove moisture. The temperature during kneading is preferably 100 to 110 ° C.

  Step (2) is a step of kneading the pigment dispersion obtained in step (1) together with the binder resin (B) to obtain a kneaded product. As the binder resin (B), those mentioned for the binder resin can be used, and may be the same as or different from the binder resin (A) in step (1). The weight ratio of the binder resin (A) and the binder resin (B) used in the production method of the present invention (binder resin (A) / binder resin (B)) is 5 / 95-40 / 60 is preferable and 10 / 90-30 / 70 is more preferable.

  Preferably, the dispersion obtained in step (1) and the raw material such as the binder resin (B) are premixed by a Henschel mixer or the like and subjected to a melt-kneading step. It can be carried out using a kneader such as an open roll type kneader. From the viewpoint of suppressing aggregation of the pigment in the binder resin, it is preferable not to lower the viscosity of the binder resin, and specifically, kneading is preferably performed at a temperature below the softening point of the binder resin (B). . In particular, the kneading is preferably performed below the softening point of either the binder resin (A) or the binder resin (B). When an open roll type continuous kneader is used as the kneader, the temperature of the kneaded material to be kneaded is kept at a temperature lower than the softening point, and therefore it is preferable to use an open roll type continuous kneader. The temperature at which kneading is performed here is the surface temperature of the kneaded product, and is measured using a laser surface thermometer at the exit of the kneader. In the open roll type continuous kneader, the kneading heat generated during kneading is easily dissipated. In some cases, the inside of the roll is divided into two or more and the temperature is set through a heat medium having different temperatures. When the temperature of the heat medium on the discharge side of the kneaded product is lower than the temperature of the heat medium on the other side, The surface temperature of the kneaded product at the discharge portion is lower than the surface temperature of the kneaded product in the heat medium portion on the other side. Therefore, in the case of an open roll type continuous kneader, the outlet part is not the kneaded product discharge part, but when the effective roll length (from the first raw material charging part to the kneaded substance discharge part) is L, the highest temperature is set. This refers to the position on the 0.05 L raw material input side from the end of the heat medium kneaded product discharge side.

  As an open roll type kneader, a machine having at least two rolls and an open type melt kneading unit is used, and a kneader having at least two rolls of a heating roll and a cooling roll is preferably used. . Such an open roll type kneader can easily dissipate kneading heat generated during melt kneading. The open roll kneader is preferably a continuous type from the viewpoint of production efficiency.

  Further, in the open roll type kneader, the two rolls are arranged close to each other in parallel, and the gap between the rolls is preferably 0.01 to 5 mm, more preferably 0.05 to 2 mm. Further, the structure, size, material, and the like of the roll are not particularly limited, and the roll surface may be any of smooth, corrugated, uneven and the like.

  The rotation speed of the roll, that is, the circumferential speed is preferably 2 to 100 m / min. The peripheral speed of the cooling roll is preferably 2 to 100 m / min, more preferably 10 to 60 m / min, and further preferably 15 to 50 m / min. The two rolls preferably have different peripheral speeds, and the ratio of the peripheral speeds of the two rolls (cooling roll / heating roll) is preferably 1/10 to 9/10, and 3/10 ˜8 / 10 is more preferable.

  The temperature of the heating roll is preferably 80 to 200 ° C, and the temperature of the cooling roll is preferably 20 to 140 ° C. The temperature difference between the heating roll and the cooling roll is preferably 60 to 150 ° C, more preferably 80 to 120 ° C.

  In addition, the temperature of a roll can be adjusted with the temperature of the heat medium passed through a roll inside, for example, and the inside of a roll may be divided into two or more and a heat medium having different temperatures may be passed through each roll.

  The mixture obtained in the step (1) and the binder resin (B) are preferably used so that the pigment content in the toner is 1 to 12% by weight, and more preferably 2 to 9% by weight.

  Step (3) is a step of pulverizing and classifying the kneaded product obtained in step (2).

  The kneaded product obtained in step (2) may be cooled and pulverized as appropriate until it reaches a pulverizable hardness. The pulverization is preferably carried out separately for coarse pulverization and fine pulverization.

  For coarse pulverization, a mechanical pulverizer such as Rotoplex (manufactured by Hosokawa Alpine Co., Ltd.) can be used.

The volume median particle diameter (D ₅₀ ) of the coarsely pulverized product is preferably 10 to 1000 μm, more preferably 10 to 750 μm, and particularly preferably 10 to ₅₀₀ μm, from the viewpoint of pulverization ability.

  Examples of the fine pulverization include jet pulverizers such as a fluidized bed jet mill and an airflow jet mill, and mechanical pulverizers such as a turbo mill (manufactured by Turbo Kogyo Co., Ltd.).

  Examples of the classifier include an air classifier, an inertia classifier, and a sieve classifier.

Since the toner of the present invention is excellent in color developability, it is possible to reduce the amount of toner used. On the other hand, since the small particle size toner can express a solid image with a smaller amount of toner, the toner of the present invention has a small particle size. Particularly effective in toner. The volume median particle diameter (D ₅₀ ) of the toner is preferably 3 to 7 μm, more preferably 3.5 to 6.5 μm, and even more preferably 4 to 6 μm.

  In the present invention, a charge control agent, a release agent, a fluidity improver, a conductivity modifier, an extender, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, a cleaning property improver, You may mix | blend additives, such as a magnetic body, as a raw material.

  Release agents include natural ester waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax and Fischer Tropu, petroleum waxes such as paraffin wax, coal waxes such as montan wax, and alcohols. Examples of the wax include wax, and these may be contained alone or in admixture of two or more.

  The melting point of the release agent is preferably from 50 to 120 ° C, more preferably from 60 to 120 ° C, from the viewpoints of low-temperature fixability and offset resistance. The blending amount of the release agent is preferably 2 to 40% by weight and more preferably 5 to 20% by weight in the raw material from the viewpoint of offset resistance and durability.

  Since the color development property of the toner of the present invention is excellent, an image in which the amount of toner used is reduced can be formed. Furthermore, when an image is formed using the toner of the present invention, a printed matter having excellent color developability can be obtained even if the toner amount is reduced.

Examples are shown below.

[Softening point]
Using a Koka flow tester (CFT-500D, manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, a 1.96 MPa load was applied by a plunger, a diameter of 1 mm, a length A nozzle of 1 mm is pushed out, thereby drawing a plunger tester descending amount (flow value) -temperature curve, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 (half of the resin) Is the softening point.

[Pigment particle diameter]
The toner embedded in the water-soluble resin is made into a thin section having a thickness of about 100 nm in a frozen state using a cryoultramicrotome, and an acceleration voltage of 100 kV and a photo magnification using a transmission electron microscope (H-8100 manufactured by Hitachi, Ltd.). The pigment dispersed in the toner is observed at 50,000 times. From the obtained transmission electron micrograph at a magnification of 50,000 times, the pigment particles and the resin phase are binarized by the software “Scion Image”, and the major axis x _i , the short diameter of 100 pigment particles for the entire pigment particles in the toner. The diameter y _i and the area particle diameter a _i are measured.
The number average major axis (x) and the number average minor axis (y) are obtained by dividing the sum of the major axis and minor axis by 100 (arithmetic mean). Further, the number average particle diameter (h = (x + y) / 2) is calculated from the number average major axis (x) and the number average minor axis (y).

[Color measurement method for printed images]
An image with thick paper on the background was measured with a colorimeter (Gretag-Macbeth SPM-50), and the light conditions were measured with an absolute white standard using a standard light source D50, an observation field of view 2 °, and a density standard DIN NB. Measure density and color coordinates. The image was output using ML3050CV (Oki Data Corporation).

[Evaluation of TMA]
The image densities of 8 to 10 solid images with different toner adhesion amounts were measured, and the relationship between the toner adhesion amount and the image density was graphed. From this graph, the toner adhesion amount at which the image density (OD) becomes 1.4 was determined.

[Evaluation of color reproducibility]
Using toners of Comparative Example 2 (Cyan), Comparative Example 4 (Magenta), and Comparative Example 5 (Yellow), the amount of adhered toner in which the image density of each primary color is in the range of 1.4 ± 0.1 is green. A solid image of red and blue secondary colors was printed. The color coordinates of each secondary color solid image were measured. The color reproducibility was evaluated based on the color coordinates of the secondary color.

A solid image of a secondary color combined with the toner to be evaluated was printed, its color coordinates were measured, and the difference from the reference was calculated as the difference c * of the saturation c *. At this time, the toner to be evaluated was also adjusted to a toner adhesion amount in which the image density of each primary color was in the range of 1.4 ± 0.1, similarly to the reference secondary color.
Δc * = {(a * -a ₀ *) ² + (b * -b ₀ *) ² } ^1/2

Here, a ₀ * and b ₀ * indicate the color coordinates of the secondary color in which the toner of the comparative example serving as a reference is combined. When the value of Δc * is positive, it indicates that the color reproduction region is enlarged, and when it is negative, it indicates that the color reproduction region is reduced.

Example 1
[Polyester A] composition ratio (molar ratio)
Acid component: Fumaric acid 100, Alcohol component: Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 96.1)
The acid component and the alcohol component were reacted with stirring at 210 ° C. under a nitrogen stream. The degree of polymerization was monitored based on the softening point, and when the softening point reached 100 ° C., the reaction was terminated to obtain polyester A.

[Polyester B] Composition ratio (molar ratio)
Acid component: terephthalic acid 92; alcohol component: polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 35, polyoxyethylene (2.2) -2,2-bis (4- Hydroxyphenyl) propane 65
Polyester B having a softening point of 110 ° C. was obtained by the same production method as for polyester A.

[Polyester C] Composition ratio (molar ratio)
Acid content: terephthalic acid 69, alkenyl succinic acid 6, trimellitic acid 25; alcohol component: polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 50, polyoxyethylene (2.2) ) -2,2-Bis (4-hydroxyphenyl) propane 50
Polyester C having a softening point of 120 ° C. was obtained by the same production method as for polyester A.

[Flushing masterbatch A]
After the crude, a precursor of copper phthalocyanine pigment (Pigment Blue 15: 3), was ground to a number average particle size of 0.03 μm by the solvent salt milling method, two pieces of filtered wet cake cake were repeatedly washed with water. While being heated to 100 to 110 ° C. using a roll, it was kneaded together with polyester A as a binder resin (A). The obtained kneaded product is cooled to such an extent that it can be pulverized, and pulverized using a mill having a 2 mmφ screen to obtain a pigment dispersion (flushing masterbatch A) consisting of 70% by weight binder resin and 30% by weight pigment. Obtained.

  [Production of Toner] 30 parts by weight of the obtained flushing masterbatch A, 55.3 parts by weight of polyester B as binder resin (B), 23.7 parts by weight of polyester C, and 0.5 parts by weight of boron salicylate complex as charge control agent (trade name: Bontron) E-84, manufactured by Orient Chemical Co., Ltd.), and a mixture of 5.5 parts by weight of carnauba wax (manufactured by Kato Yoko Co., Ltd.) as a wax, using a Henschel mixer (capacity 20 liters), setting the blade rotation speed to 1500 times / minute And premixed for 1 minute.

  The obtained mixture was continuously fed by a table feeder at a feed rate of 10 kg / h with a continuous two-open roll type kneader “NIDEX” (Mitsui Mining Co., Ltd., roll outer diameter: 0.14 m, effective roll length ( L): 0.8 m) to obtain a kneaded product. The operating conditions of the kneader are: the rotation speed of the heating roll (front roll) is 75 times / minute (circumferential speed 33 m / min), and the rotational speed of the cooling roll (rear roll) is 50 times / minute (circumferential speed 22 m / min). min), the gap between the rolls was adjusted to 0.1 mm. The heating medium temperature in the roll was set to 145 ° C on the raw material input side of the heating roll, 100 ° C on the kneaded material discharge side, 75 ° C on the raw material input side of the cooling roll, and 30 ° C on the kneaded material discharge side. . The surface temperature of the kneaded material at the position on the 0.05 L raw material input side from the end of the heat medium on the raw material input side on the kneaded material discharge side was 105 ° C.

  The obtained kneaded material was cooled with a cooling belt and then coarsely pulverized with a mill having a 2 mmφ screen. Next, 1.0 part by weight of hydrophobic silica “Aerosil R-972” (manufactured by Nippon Aerosil Co., Ltd.) was mixed with 100 parts by weight of the coarsely crushed material using a Henschel mixer, and silica was externally added to the surface of the crushed material.

  Thereafter, the mixture was pulverized by a collision plate type jet mill, and further, coarse powder and fine powder were removed by a cyclone type air classifier to obtain toner particles having a volume median particle diameter of 6.0 μm. The average particle size of the toner particles was measured with a Coulter Multisizer.

  Further, 100 parts by weight of the obtained toner particles, 1.2 parts by weight of hydrophobic silica “Aerosil RY-50” (manufactured by Nippon Aerosil Co., Ltd.), 0.4 part by weight of “HVK-2150” (manufactured by Clariant Japan), and “Caboseal TS- 530 "(Cabot Specialty Chemicals) 0.3 parts by weight was mixed using a Henschel mixer, and silica was externally added to the toner surface.

  When the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the number average particle diameter was 0.048 μm, and the pigment having an area particle diameter of 0.22 μm or more was 0 area%.

Example 2
[Flushing masterbatch B]
Crude, the precursor of dimethyl quinacridone pigment (Pigment Red 122), is ground to a number average particle size of 0.03 μm by the solvent salt milling method, and then the filtered wet pigment cake is washed with two rolls. The mixture was kneaded with polyester A as the binder resin (A) while heating to 100 to 110 ° C. The obtained kneaded product is cooled to such an extent that it can be pulverized, and pulverized using a mill having a 2 mmφ screen to obtain a pigment dispersion (flushing masterbatch B) consisting of 70% by weight binder resin and 30% by weight pigment. Obtained.

  [Production of Toner] 20 parts by weight of the obtained flushing masterbatch B, 56 parts by weight of polyester B as binder resin (B), 30 parts by weight of polyester C, and 0.5 parts by weight of boron salicylate complex as a charge control agent (trade name: Bontron) E-84, manufactured by Orient Chemical Co., Ltd.), and a mixture of 5.5 parts by weight of carnauba wax (manufactured by Kato Yoko Co., Ltd.) as a wax, using a Henschel mixer (capacity 20 liters), setting the blade rotation speed to 1500 times / minute And premixed for 1 minute.

  A kneaded material was obtained from the obtained mixture in the same manner as in Example 1. The surface temperature of the kneaded material at the position on the 0.05 L raw material charging side from the end on the raw material charging side heat medium kneaded material discharging side was 105 ° C. Further, in the same manner as in Example 1, silica was externally added, pulverized, classified, and externally added again to obtain a toner.

  When the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the number average particle diameter was 0.035 μm, and the pigment having an area particle diameter of 0.22 μm or more was 0 area%.

Example 3
[Flushing masterbatch C]
Crude, which is a precursor of isoindoline pigment (Pigment Yellow 185), is ground to a number average particle size of 0.045 μm by the solvent salt milling method, and then the filtered wet pigment cake is washed with two rolls. Was kneaded with polyester A as binder resin (A) while heating to 100 to 110 ° C. The obtained kneaded product is cooled to such an extent that it can be pulverized, and pulverized using a mill having a 2 mmφ screen to obtain a pigment dispersion (flushing masterbatch C) comprising 70% by weight of binder resin and 30% by weight of pigment. Obtained.

  [Production of Toner] 15 parts by weight of the obtained flushing masterbatch C, 59.5 parts by weight of polyester B as a binder resin (B), 30 parts by weight of polyester C, and 0.5 parts by weight of a boron salicylate complex as a charge control agent (trade name: Bontron) E-84, manufactured by Orient Chemical Co., Ltd.), and a mixture of 5.5 parts by weight of carnauba wax (manufactured by Kato Yoko Co., Ltd.) as a wax, using a Henschel mixer (capacity 20 liters), setting the blade rotation speed to 1500 times / minute And premixed for 1 minute.

  A kneaded material was obtained from the obtained mixture in the same manner as in Example 1. The surface temperature of the kneaded material at the position on the 0.05 L raw material charging side from the end portion on the raw material charging side of the heat medium kneaded material discharging side was 98 ° C. Further, in the same manner as in Example 1, silica was externally added, pulverized, classified, and externally added again to obtain a toner.

  Although the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the pigment particles were unclear and the particle size could not be determined by image analysis, but it is considered that the pigment particles were dispersed at an equivalent of 0.045 μm.

Comparative Example 1
[Production of Toner] 30 parts by weight of the flushing masterbatch A used in Example 1, 55.3 parts by weight of polyester B as a binder resin (B), 23.7 parts by weight of polyester C, and 0.5 parts by weight of boron salicylate complex as a charge control agent ( Product name: Bontron E-84, manufactured by Orient Chemical Co., Ltd.) and a mixture of carnauba wax 5.5 parts by weight (manufactured by Kato Yoko Co., Ltd.) as a wax using a Henschel mixer (capacity 20 liters), blade rotation speed 1500 times Set to / min and premixed for 1 minute.

  The obtained mixture was kneaded with a twin-screw extrusion kneader. The operating conditions when using this biaxial extrusion kneader were as follows: the barrel (kneading extruder outer cylinder) set temperature was 110 ° C. and the kneading temperature was 70 ° C. The temperature at the outlet of the resin by this kneading was 116 ° C.

  After kneading, a toner was produced in the same manner as in Example 1.

  When the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the number average particle diameter was 0.064 μm, and the pigment having an area particle diameter of 0.22 μm or more was 9 area%. It was observed that the pigment reaggregated and was present as secondary particles.

Comparative Example 2
[Flushing masterbatch D]
In the same manner as the flushing masterbatch A used in Example 1, a pigment dispersion (flushing masterbatch D) of copper phthalocyanine pigment (Pigment Blue 15: 3) having a number average particle size of 0.06 μm was obtained.

  [Production of toner] 30 parts by weight of flushing masterbatch D, 55.3 parts by weight of polyester B as binder resin (B), 23.7 parts by weight of polyester C, 0.5 parts by weight of boron salicylate complex as charge control agent (trade name: Bontron E- 84, manufactured by Orient Chemical Co., Ltd.), and a mixture of carnauba wax 5.5 parts by weight (manufactured by Kato Yoko Co., Ltd.) as a wax, using a Henschel mixer (capacity 20 liters), setting the blade rotation speed to 1500 times / minute Premixed for minutes.

  A toner was produced in the same manner as in Example 1.

  When the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the number average particle diameter was 0.068 μm, and the pigment having an area particle diameter of 0.22 μm or more was 8 area%.

Comparative Example 3
[Raw Pigment] Using the solvent salt milling method described in Example 1, the copper phthalocyanine pigment was ground to a number average particle size of 0.03 μm, washed repeatedly with water and dried to obtain a raw pigment. .

[Production of Toner] 9 parts by weight of the obtained raw pigment, 70 parts by weight of polyester B as a binder resin, 30 parts by weight of polyester C, and 0.5 parts by weight of boron salicylate complex as a charge control agent (trade name: Bontron E-84) , Orient Chemical Industry Co., Ltd.), and a mixture of carnauba wax 5.5 parts by weight (manufactured by Kato Yoko Co., Ltd.) using a Henschel mixer (capacity 20 liters) and setting the blade rotation speed to 1500 times / minute. Premixed for minutes.

  Thereafter, a toner was produced in the same manner as in Example 1.

  When the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the number average particle diameter was 0.051 μm, and the pigment having an area particle diameter of 0.22 μm or more was 22 area%. It was observed that there were agglomerated particles and the dispersion was poor.

Comparative Example 4
[Raw Pigment] Using the solvent salt milling method under the same conditions as in Example 2, the dimethylquinacridone pigment is ground to a number average particle size of 0.1 μm, and after washing with water, the filtrate is dried and the raw pigment is dried. It was.

[Production of toner] 6 parts by weight of the obtained raw pigment, 70 parts by weight of polyester B as a binder resin, 30 parts by weight of polyester C, and 0.5 parts by weight of a boron salicylate complex as a charge control agent (trade name: Bontron E-84) , Orient Chemical Industry Co., Ltd.), and a mixture of carnauba wax 5.5 parts by weight (manufactured by Kato Yoko Co., Ltd.) using a Henschel mixer (capacity 20 liters) and setting the blade rotation speed to 1500 times / minute. Premixed for minutes.

  Thereafter, a toner was produced in the same manner as in Example 1.

  When the pigment dispersion state of the obtained toner was observed with a transmission electron microscope, the number average particle diameter was 0.110 μm, and the pigment having an area particle diameter of 0.22 μm or more was 11 area%. It was observed that there were agglomerated particles and the dispersion was poor.

Comparative Example 5
[Raw pigment] Using the solvent salt milling method under the same conditions as in Example 3, the isoindoline pigment was ground to a number average particle size of 0.08 μm, washed repeatedly with water, and the filtrated material was dried and dried. A pigment was used.

[Production of Toner] 4.5 parts by weight of the obtained raw pigment, 70 parts by weight of polyester B as a binder resin, 30 parts by weight of polyester C, 0.5 parts by weight of a boron salicylate complex as a charge control agent (trade name: Bontron E-84) , Orient Chemical Industry Co., Ltd.), and a mixture of carnauba wax 5.5 parts by weight (manufactured by Kato Yoko Co., Ltd.) using a Henschel mixer (capacity 20 liters) and setting the blade rotation speed to 1500 times / minute. Premixed for minutes.

  Thereafter, a toner was produced in the same manner as in Example 1.

  The pigment dispersion state of the obtained toner was observed with a transmission electron microscope, but the pigment particles were unclear and the particle diameter could not be measured.

  The image density with respect to the toner amount on the paper surface in a single color was examined. The results are shown in Table 1. As for cyan, the toner of Example 1 showed a higher image density than the toners of Comparative Examples 1 to 3. The effect was particularly remarkable in the low TMA region. For magenta, the toner of Example 2 has a higher image density than the toner of Comparative Example 4, and for yellow, the toner of Example 3 has a higher image density than the toner of Comparative Example 5.

  Using these toners, a color reproduction region of secondary colors was examined using a non-magnetic one-component full-color electrophotographic recording device ML3050CV (Oki Data Co., Ltd.). Combination of cyan example 1, comparative example 1 or comparative example 3 and magenta comparative example 4 or yellow comparative example 5 (yellow), combination of magenta example 2 and yellow comparative example 5, yellow For the combination of Example 3 and Cyan Example 1, a solid image of a secondary color was printed and the color coordinates were evaluated. The results are shown in Tables 2-4. The color reproducibility of the toners shown in Examples 1 to 3 was good.

  In Comparative Example 1, a twin-screw extrusion type kneader was used. However, since kneading is performed in a closed system as compared with an open roll type kneader, it is considered that heat generated during kneading caused reaggregation of the pigment.

  The toner obtained by using the present invention exhibits excellent dispersibility in a pigment of less than 0.05 μm, which has conventionally caused aggregation and reaggregation, and has good secondary color reproducibility and coloring power.

  The toner of the present invention is suitably used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (10)

  A toner for developing an electrostatic charge image containing a binder resin and a pigment, wherein the number average particle diameter (h = (x + y) calculated from the number average major axis (x) and the number average minor axis (y) of the pigment in the toner. ) / 2) is an electrostatic charge image developing toner having a value of 0.01 μm or more and less than 0.05 μm.   2. The toner for developing an electrostatic charge image according to claim 1, wherein the ratio of the area particle diameter of the pigment in the toner of 0.22 μm or more is 5 area% or less. The electrostatic charge image developing toner according to claim 1, wherein the toner has a volume-median particle diameter (D ₅₀ ) of 3 to 7 μm.   The toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the content of the pigment in the toner is 1 to 10% by weight. A method for producing a toner for developing an electrostatic image comprising the following steps.
Step (1): A pigment having a number average particle diameter (h = (x + y) / 2) calculated from the number average major axis (x) and the number average minor axis (y) of particles of 0.01 μm or more and less than 0.05 μm. Kneading with the binder resin (A) without going through a drying step to obtain a pigment dispersion,
Step (2): Step of kneading the pigment dispersion with the binder resin (B) to obtain a kneaded product, and Step (3): Step of pulverizing and classifying the kneaded product   6. The method for producing a toner for developing an electrostatic charge image according to claim 5, wherein the pigment concentration in the pigment dispersion in step (1) is 10 to 70% by weight.   The method for producing a toner for developing an electrostatic charge image according to claim 5 or 6, wherein the kneading in the step (2) is performed at a temperature below the softening point of the binder resin (B).   The method for producing a toner for developing an electrostatic charge image according to any one of claims 5 to 7, wherein the kneading in the step (2) is carried out with an open roll type continuous kneader.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 5 to 8, wherein the pigment of the step (1) is subjected to salt milling.   An image forming method using the electrostatic image developing toner according to claim 1.