JP2006119616A - Process for preparing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for preparing a toner having a small particle size and excellent in durability. <P>SOLUTION: The process for preparing the toner includes steps of: (I) of melt-kneading a resin binder and a colorant; (II) coarsely crushing the resulting kneaded material to 10-1,000 μm; (III) pulverizing the resulting coarsely crushed product in the presence of an external additive having an average particle size of 8-50 nm; and (IV) classifying the resulting pulverized product. The resulting toner has a volume-median particle size of 3.5-8 μm, and the total amount of m kind(s) of external additive(s) in the step (III) satisfies formula (a), wherein Dt denotes a volume-median particle size of the toner; dn denotes an average particle size of the external additive n; pt denotes a true density of toner base particles; pn denotes a true density of the external additive n; Cn denotes a weight ratio of the external additive n to the coarsely crushed product; and m denotes an integer of ≥1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

  Conventionally, toner having a particle size of about 10 μm has been used in many cases. However, with the recent improvement in image quality of electrophotography, it is desired to reduce the toner particle size. However, since the toner having a small particle size has a stronger cohesion force between the toners than the toner having a conventional particle size, the toner is not well dispersed during the external addition process, and the adhesion of the external additive tends to be reduced. . When such an external additive having a weak adhesive force is liberated during toner use in an actual machine, the durability of the toner may be deteriorated.

On the other hand, as a method for producing a toner, there has been proposed means for mixing and pulverizing a coarsely pulverized kneaded material with a fluidity imparting agent such as silica or an inorganic oxide (see Patent Document 1 and Patent Document 2).
JP 2002-131979 (Claim 1) JP 2004-126260 A (Claim 1)

  An object of the present invention is to provide a method for producing a toner having a small particle diameter and excellent durability.

The present invention
Step (I) of melt-kneading a raw material containing a binder resin and a colorant, the kneaded product obtained in step (I) is cooled, and coarsely pulverized to a volume-median particle size (D ₅₀ v) of 10 to 1000 μm Step (II), pulverizing the coarsely pulverized product obtained in step (II) in the presence of an external additive having an average particle size of 8 to 50 nm in step (III), and step (III) A method for producing a toner comprising a step (IV) of classifying the obtained finely pulverized product, wherein the obtained toner has a volume median particle size (D ₅₀ v) of 3.5 to 8 μm, and m in the step (III) The total abundance of the types of external additives is represented by the formula (a):

[Where Dt is the volume-median particle size (D ₅₀ v, μm) of the target toner, dn is the average particle size (μm) of the external additive n, ρt is the true density of the toner base particles, and ρn is the external density The true density of additive n, Cn is the weight ratio of external additive n to the coarsely pulverized product (external additive n / coarly pulverized product), and m is an integer of 1 or more.
The present invention relates to a toner production method that satisfies

  According to the present invention, a toner having a small particle diameter and excellent durability can be obtained.

The toner production method of the present invention comprises at least step (I): a step of melt-kneading a raw material containing a binder resin and a colorant,
Step (II): a step of cooling and coarsely pulverizing the kneaded product obtained in Step (I),
Step (III): Step of finely pulverizing the coarsely pulverized product obtained in Step (II) in the presence of an external additive, and Step (IV): Step of classifying the finely pulverized product obtained in Step (III) In particular, step (III) has a great feature.

  In the present invention, in the process of coarsely pulverizing the kneaded product and further finely pulverizing and classifying it in the production of the toner, the finely pulverizing step (III) is performed in the presence of an external additive having a specific particle size. As a result, it is possible to obtain a toner in which the external additive is uniformly and evenly applied to the surface of the toner base particles with an appropriate adhesive force. That is, the present inventors perform surface treatment simultaneously with pulverization by allowing an external additive having a specific particle size to exist during the pulverization process in which the coarsely pulverized product maintains good dispersibility in the pulverizer. As a result, the present inventors have found that a toner having excellent durability, in which an external additive adheres well even with a small particle size, can be obtained.

  In the present invention, when a small particle size toner is produced, an appropriate amount of the external additive is present at the time of pulverization, whereby a toner having a good external additive can be finally obtained.

  The external additive used in step (III) may be one type or a plurality of types, and is not particularly limited. The total abundance when m kinds of external additives are used is the formula (a):

[Where Dt is the volume-median particle size (D ₅₀ v, μm) of the target toner, dn is the average particle size (μm) of the external additive n, ρt is the true density of the toner base particles, and ρn is the external density The true density of additive n, Cn is the weight ratio of external additive n to the coarsely pulverized product (external additive n / coarly pulverized product), and m is an integer of 1 or more.
Satisfied. In formula (a):

Represents the coverage of the external additive on the toner base particles. In calculating the coverage, the toner base particles are assumed to be spheres having a volume-median particle diameter Dt, and the external additive n is assumed to be a sphere having an average particle diameter dn. For example, the coverage of the external additive n is calculated by the following method.
1) The total amount (A) of the external additive n is obtained by multiplying Cn by the weight of the toner base particles.
(A) = Cn × ρt × (4/3) × π × (0.5 × Dt) ³
2) The total number (B) of external additives n can be obtained by dividing the total amount of external additives (A) by the weight per external additive n.
(B) = (A) / (ρn × (4/3) × π × (0.5 × dn) ³ )
3) The coverage of external additive n is divided by the total projected area of external additive n (because it adheres to the toner surface, the area contribution rate of external additive n is assumed to be the projected area, ie, a circle). can get. That is, the coverage (C) of the external additive n is
(C) = 100 × (B) × π × (0.5 × dn) ² /(4×π×(0.5×Dt) ² )
= (Dt × ρt × Cn × 100) / (4 × dn × ρn)
4) If there are m types of external additives, perform the same calculation as above for each type of external additive and take the sum.

  In the formula (a), the coverage of the external additive on the toner base particles is multiplied by 1/2 because the external additive generally remaining on the toner surface after pulverization is the external additive used during pulverization. This is because it is about 50%. The remaining 50% is recovered with fines. In the present invention, toner base particles mean toner having no external additive on the surface. The true density of the toner base particles can be measured by the method described in Examples below. This true density can be used as a reference with reference to the value of the externally treated toner.

  The lower limit of formula (a) is 10 or more, preferably 20 or more, more preferably 30 or more, from the viewpoint of imparting fluidity. Further, the upper limit of the formula (a) is 180 or less, preferably 160 or less, more preferably 155 or less, and further preferably 140 or less, in order to suppress the free external additive generated in the obtained toner. .

  As the external additive, inorganic oxides such as silica, titania, alumina, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, and tin oxide are preferable. Is preferred.

The fine powder of silica (SiO ₂ ) may be either a dry method or a wet method. In addition to anhydrous silica, it may contain aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, etc., but preferably contains SiO _{2 in an amount} of 85% by weight or more.

Further, the surface of the external additive may be subjected to a hydrophobic treatment. The method of hydrophobizing treatment is not particularly limited. Examples of the hydrophobizing agent include silane coupling agents such as hexamethyldisilazane (HMDS) and dimethyldichlorosilane (DMDS), and silicones such as dimethyl silicone oil and amino-modified silicone oil. Examples include oil treating agents, and among these, silane coupling agents are preferred. The treatment amount with the hydrophobizing agent is preferably 1 to 7 mg / m ² per surface area of the external additive.

  The average particle diameter of the external additive is 8 to 50 nm, preferably 8 to 40 nm, and more preferably 12 to 20 nm from the viewpoint of imparting fluidity. Here, the average particle diameter is a number average particle diameter.

  As a method of finely pulverizing the coarsely pulverized product in the presence of the external additive, a method of mixing the coarsely pulverized product with the external additive in advance before pulverization, combining both when supplying to the pulverizer, and simultaneously supplying both to the pulverizer In the present invention, a method of mixing the coarsely pulverized product with the external additive in advance is preferable from the viewpoint of adhesion of the external additive. .

  When the coarsely pulverized product and the external additive are supplied to the pulverizer, the pulverization proceeds due to the collision between the coarsely pulverized products, while the collision between the (coarse) pulverized product and the external additive occurs, and the external additive is present on the surface of the pulverized product. Adhere to. By coexisting the amount of the external additive corresponding to the target toner, the external additive can be attached to the surface of the toner base particles with an appropriate amount and adhesive force.

  The coarsely pulverized product and the external additive can be mixed with a mixer capable of high-speed stirring such as a Henschel mixer and a super mixer.

  Examples of the pulverizer used for the fine pulverization in the step (III) include a fluidized bed jet mill, a jet pulverizer such as an airflow jet mill, and a mechanical pulverizer such as a turbo mill. A jet mill is preferred.

  The fluidized bed jet mill used in the present invention has at least a pulverization chamber arranged so that a plurality of jet nozzles are opposed to each other in the lower part, and a high-speed gas jet ejected from the jet nozzles in the pulverization vessel. A pulverizer having a structure / principle in which particles are finely pulverized by forming a fluidized bed of supplied particles and repeating particle acceleration and mutual collision in the fluidized bed is preferable. The pulverization pressure of the fluidized bed jet mill is preferably 0.5 to 1 MPa, more preferably 0.6 to 0.9 MPa, from the viewpoint of uniform adhesion of the external additive to the toner.

  In the pulverizer having the above-described structure, the number of jet nozzles is not particularly limited, but a plurality of, preferably 3 to 4, jet nozzles face each other from the viewpoint of air volume, flow rate, flow velocity balance, particle collision efficiency, and the like. Are preferably arranged.

  Furthermore, a classifying rotor is provided in the upper part of the crushing chamber to collect particles that have been reduced in size by crushing and that have risen. The particle size distribution can be easily adjusted by the rotation speed of the classification rotor. A finely pulverized product (upper classified powder) is obtained by classification with a classification rotor.

  The classification rotor may be arranged either vertically or horizontally with respect to the vertical direction, but is preferably arranged vertically from the viewpoint of classification performance.

  Specific examples of the fluidized bed jet mill provided with a plurality of jet nozzles and further having a classification rotor include pulverizers disclosed in JP-A-60-166547 and JP-A-2002-35631.

  Examples of the fluidized bed jet mill preferably used in the present invention include “TFG” series manufactured by Hosokawa Micron Corporation, “AFG” series manufactured by Hosokawa Micron Corporation, and the like.

  Moreover, as an airflow type jet mill, the collision type jet mill provided with the venturi nozzle and the collision member arrange | positioned so as to oppose this venturi nozzle, etc. are mentioned, for example.

  As an air flow type jet mill suitably used in the present invention, “IDS” series manufactured by Nippon Pneumatic Co., Ltd. and the like can be mentioned.

The volume-median particle size (D ₅₀ v) of the finely pulverized product is preferably 3 to 7.5 μm, more preferably 3.5 to 7 μm.

  Hereinafter, steps (I), (II), and (IV) will be described.

  Step (I) is a step of melt-kneading a raw material containing a binder resin and a colorant.

  Examples of the binder resin 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 the viewpoint of dispersibility and transparency of the colorant. It is preferable that polyester is 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 or polyamide and an addition polymerization resin such as vinyl polymerization resin are partially chemically bonded, and two or more kinds of resins are used as raw materials. May be obtained from a mixture of raw material monomers of one kind of resin and another kind of resin, but 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 acid value of the polyester is preferably 5 to 40 mgKOH / g, more preferably 10 to 35 mgKOH / g, and even more preferably 15 to 30 mgKOH / g.

  The softening point of the polyester is preferably 80 to 165 ° C, and the glass transition point is preferably 50 to 85 ° C.

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used, and these can be used alone or in admixture of two or more. The toner produced according to the present invention is a black toner. Any of color toners may be used. The amount of the colorant used is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  In the toner of the present invention, charge control agents, mold release agents, fluidity improvers, conductivity modifiers, extender pigments, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, and improved cleaning properties You may mix | blend additives, such as an agent and 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. Usually, if a large amount of release agent is used, the pulverized product is likely to be fused at the time of pulverization, and the pulverization efficiency is likely to decrease.In the present invention, even when a large amount of release agent is used, pulverization is efficient. can do.

  In the present invention, the raw materials such as binder resin, colorant, release agent and the like are preferably premixed by a Henschel mixer or the like and subjected to a melt-kneading step. In accordance with the above, it can be carried out using a known kneader such as a hermetic kneader, a single or twin screw extruder, and an open roll kneader.

  For example, as an open roll type kneader, a machine having at least two rolls and having 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 used. Is preferred. 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.

  In order to make the kneaded material easily stick to the heating roll, the temperature of the heating roll is higher than the softening point of the binder resin and the melting point of the wax, and the temperature of the cooling roll is the softening point of the binder resin and the melting point of the wax. It is preferable that the temperature is adjusted to be lower than any of the above. Specifically, 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 temperature of the heating roll, particularly the raw material charging side, is preferably higher than the softening point of the binder resin and the melting point of each wax, and is 0 to 80 ° C. higher than the higher one of them. More preferably, it is more preferably 5 to 50 ° C. higher. Further, the temperature of the cooling roll is preferably lower than the softening point of the binder resin and the melting point of each wax, and is preferably 0 to 80 ° C. lower than the lower one of them. Preferably, the temperature is lower by 40 to 80 ° C.

  Step (II) is a step in which the kneaded product obtained in step (I) is cooled and coarsely pulverized.

  The temperature at which the kneaded product is cooled is not particularly limited, and may be appropriately cooled until the kneaded product reaches a hardness that can be pulverized.

  An atomizer, a rotoplex, etc. can be used for rough pulverization.

The volume median particle size (D ₅₀ v) of the coarsely pulverized product is 10 to 1000 μm, preferably 10 to 250 μm, more preferably 10 to 100 μm, from the viewpoint of pulverization ability.

  The coarsely pulverized product obtained in the step (II) is subjected to the step (III), and the obtained finely pulverized product is subjected to the subsequent step (IV).

  Step (IV) is a step of classifying the finely pulverized product obtained in step (III).

  Examples of the classifier used in step (IV) include an air classifier, an inertia classifier, and a sieve classifier. In the present invention, from the viewpoint of the ability to remove fine powder, the vertical direction in the casing. The classifying rotor with the driving shaft as the central axis and the same driving shaft as the classifying rotor as the central axis, and the classifying rotor at the outer periphery of the classifying rotor are spaced apart from the outer periphery of the classifying rotor It is preferable that the classifier has a stationary spiral guide blade. Specific examples of the classifier having such a structure include the classifier shown in FIG. 2 of JP-A-11-216425, FIG. 6 of JP-A-2004-78063, “TSP” series manufactured by Hosokawa Micron Corporation, and the like. The outline of the classification mechanism will be described below.

  The pulverized material supplied into the casing of the classifier descends the classifying zone on the outer periphery of the classifying rotor while being guided by the spiral guide vanes. The inside of the classification rotor and the classification zone communicate with each other through the classification blades provided on the outer peripheral surface of the classification rotor, and when the pulverized material descends, the fine powder on the classification air passes through the classification blades and is inside the classification rotor. And is discharged from the fine powder outlet. On the other hand, the coarse powder that did not get on the classified air flow descends in the classification zone by gravity and is discharged from the coarse powder discharge port.

  Further, the classifier used in step (IV) preferably has two classifying rotors having the same drive shaft as the central axis in one casing, and the classifying rotors are independently in the same direction. It is preferable to rotate. Specific examples of classifiers equipped with a classifying rotor in two upper and lower stages include the classifier shown in FIG. 1 of JP-A-2001-293438, and commercially available products such as the “TTSP” series manufactured by Hosokawa Micron. It is done.

  In the case where the classification rotor is provided in two upper and lower stages, it is possible to classify with higher accuracy by adjusting the suction speed of classification air, the rotation speed of the classification rotor, and the like.

  For example, the ratio of the rotation speed of the upper classification rotor to the rotation speed of the lower classification rotor (the rotation speed of the upper classification rotor / the rotation speed of the lower classification rotor) is 1 / 1.05 to 1.05 / 1 is preferable, and 1/1 is more preferable.

The air flow rate introduced from the upper classification air suction port and the air flow rate introduced from the lower classification air suction port are preferably substantially equal from the viewpoint of classification accuracy and toner yield.

  The classifier used in step (IV) is preferably used mainly for the lower limit classification for removing fine powder. The fine powder removed by the classification step may be subjected to step (IV) in order to re-collect necessary parts by reclassification.

The volume median particle size (D ₅₀ v) of the toner obtained by the present invention is 3.5 to 8 μm, preferably 3.5 to 7 μm, more preferably 3.5 to 6.5 μm, and further preferably 4 to 6 μm. The number median particle size (D ₅₀ p) of the toner is preferably 3 to 7.5 μm, more preferably 3 to 6.5 μm, and still more preferably 3 to 6 μm. The toner obtained by the present invention in which the pulverization step is performed in the presence of an external additive has sufficient dispersibility even with a small particle size and has low cohesion. An additive may be added. That is, the method of the present invention may further include a step (V) of adding an external additive to the toner obtained in the step (IV).

Standard deviation of the volume particle size distribution of the toner, the shear applied to each toner in a developing machine and to the same extent, from the viewpoint of long life of the toner, less than 1/4 preferably D ₅₀ v, more preferably D ₅₀ 1/7 to 1/4 of v.

The content of particles having a particle size of (1.4 × D ₅₀ v) μm or more is 5% by volume in the toner from the viewpoint of suppressing an increase in free external additives due to a decrease in the specific surface area of the toner and improving durability. The following is preferable, and 4% by volume or less is more preferable. On the other hand, the fluidity associated with lack of external additives due to the increase of the specific surface area of the toner, and prevent deterioration of the charging property, from the viewpoint of improving the durability, grain size of (0.6 × D ₅₀ p) μm or smaller particles The content is preferably 5% by number or less and more preferably 4% by number or less in the toner.

  The toner obtained by the present invention is a magnetic one-component developing toner alone when containing magnetic fine powder, and a non-magnetic one-component developing toner when not containing magnetic fine powder, or mixed with a carrier. The two-component developing toner to be used is not particularly limited and can be used for any developing method.

[Softening point of resin]
Using a flow tester (CFT-500D, manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, and a load of 1.96 MPa was applied by a plunger, with a diameter of 1 mm and a length of 1 mm. The nozzle is pushed out, and this draws the plunger descent amount-temperature curve of the flow tester. When the height of the S-shaped curve is h, the temperature corresponding to h / 2 (the temperature at which half of the resin flows out) The softening point.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C., and the sample cooled from that temperature to 0 ° C. at a cooling rate of 10 ° C./min was measured at a heating rate of 10 ° C./min. The temperature at the intersection of the base line extension below the maximum endothermic peak temperature and the tangent showing the maximum slope from the peak rising portion to the peak apex is defined as the glass transition point.

[Volume-median particle size of coarsely pulverized product (D ₅₀ v)]
(1) Sieve 100 g of coarsely pulverized product with sieves having openings of 2000 μm, 1000 μm, 850 μm, 500 μm, 355 μm, 250 μm, 150 μm, 75 μm and 45 μm. The coarsely pulverized product that has been used from a sieve with a large opening and passed through the sieve is passed through a sieve with a small opening in turn.
(2) Measure the weight frequency (%) by measuring the weight of the coarsely pulverized material remaining on each sieve.
(3) The volume-median particle size (D ₅₀ v) of the coarsely pulverized product is obtained from the following formula.
D ₅₀ v (μm) = 2000 × (weight frequency of coarsely pulverized product on a 2000 μm sieve) +
1000 × (Weight frequency of coarsely pulverized material on a 1000 μm sieve) +
850 x (Weight frequency of coarsely pulverized product on 850 μm sieve) +
500 x (weight frequency of coarsely pulverized material on a 500 µm sieve) +
355 x (weight frequency of coarsely pulverized material on a 355 μm sieve) +
250 × (Weight frequency of coarsely pulverized material on 250 μm sieve) +
150 × (Weight frequency of coarsely pulverized product on 150 μm sieve) +
75 × (weight frequency of coarsely pulverized product on 75 μm sieve) +
45 × (Weight frequency of coarsely pulverized material on a 45 μm sieve)

[Average particle size of external additives]
Obtained from the following formula.
Average particle diameter (μm) = 6 / (ρ × specific surface area (m ² / g))
In the formula, ρ is the specific gravity of the external additive, and the specific surface area is the BET specific surface area determined by the nitrogen adsorption method of the raw material before the hydrophobic treatment. The specific gravity of silica is 2.2 and the specific gravity of titanium oxide is 4.2.
The above formula is assumed to be a sphere having a particle size R,
BET specific surface area = S x (1 / m)
m (weight of particle) = 4/3 x π x (R / 2) ³ x density
S (surface area) = 4π (R / 2) ²
Is an expression obtained from

[Particle size distribution of toner]
Using a Coulter counter “Coulter Multisizer II” (manufactured by Beckman Coulter, Inc.), the toner particle size distribution is determined according to the following method.

(1) Preparation of dispersion: Add 10 mg of measurement sample to 5 ml of dispersion (Emulgen 109P (Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% by weight aqueous solution), and use ultrasonic disperser for 1 minute Then, 25 ml of an electrolytic solution (Isoton II (manufactured by Beckman Coulter)) is added, and further dispersed for 1 minute with an ultrasonic disperser to obtain a dispersion.
(2) Measuring device: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100 μm
Measurement particle size range: 2-60μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
(3) Measurement conditions: 100 ml of electrolyte solution and dispersion are added to a beaker, and the particle size of 30,000 particles is measured at a concentration capable of measuring the particle size of 30,000 particles in 20 seconds.
(4) From the measured values, the content of particles having a volume median particle size (D ₅₀ v, μm), a number median particle size (D ₅₀ p, μm), and a particle size of (1.4 × D ₅₀ v) μm or more. (Volume%), content (number%) of particles having a particle size of (0.6 × D ₅₀ p) μm or less, and standard deviation in volume particle size distribution are determined.

[True density]
Using “MULTIVOLUME PYCNOMETER 1305” (manufactured by Shimadzu Corporation), the true density (g / cm ³ ) of the sample is obtained. At this time, a sample container of 10 cm ³ is used, and as a pretreatment of the sample, helium gas purge is performed 3 times at 19.3 to 19.7 psi · G (1 psi = 6.89476 × 10 ⁵ Pa). The measurement is performed three times, and the average value is the true density.
Note that “MULTIVOLUME PYCNOMETER 1305” is based on the pressure when filling a sample chamber of unknown volume filled with helium gas and the pressure after connecting this sample chamber to the expansion chamber of a certain volume. This is a device that calculates the true density from the sample volume and the sample weight by obtaining the sample volume based on the above law.

Examples of resin production Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 568 g, Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 792 g, Terephthalic acid 640 g, and 10 g of tin octylate was reacted while being stirred at 210 ° C. under a nitrogen stream. The degree of polymerization was monitored by the softening point, and the reaction was terminated when the softening point reached 110 ° C. The obtained resin is referred to as Resin A. The glass transition point of Resin A was 68 ° C.

Examples 1-3, 7
100 parts by weight of resin A, 4.5 parts by weight of coloring agent “ECB-301” (manufactured by Dainichi Seika Kogyo Co., Ltd.), 6.0 parts by weight of release agent “carnauba wax C1” (manufactured by Kato Yoko) and charge control agent “Bontron E” -304 "(Orient Chemical Co., Ltd.) 0.2 parts by weight was mixed with a Henschel mixer, and the resulting mixture was kneaded with a continuous two-open roll type kneader" Needex "(Mitsui Mine Co., Ltd.). A kneaded product was obtained.

  The continuous two-open roll type kneader used has a roll outer diameter of 0.14 m and an effective roll length of 0.8 m, and the operating condition is that the rotation speed of the high rotation side roll (front roll) is 75. The number of rotations per minute, the number of rotations of the low rotation side roll (rear roll) was 50 rotations / minute, and the roll gap was 0.1 mm. The heating and cooling medium temperature in the roll is 150 ° C on the raw material input side of the high-rotation roll, 130 ° C on the kneaded material discharge side, 35 ° C on the raw material input side of the low-rotation roll, and the kneaded material discharge side. The temperature of was set to 30 ° C. The feed rate of the raw material mixture was 10 kg / hour.

Next, the obtained kneaded product was cooled in air, and then coarsely pulverized with an Alpine Rotoplex (manufactured by Hosokawa Micron Corporation) to obtain a coarsely pulverized product having a volume-median particle size (D ₅₀ v) of 500 μm.

  The external additives shown in Table 1 were mixed with 100 parts by weight of the coarsely pulverized product using a Henschel mixer, and the resulting mixture was mixed with a counter jet mill “400AFG” (manufactured by Hosokawa Micron Corporation) at a pulverization pressure of 0.8 MPa. Finely pulverized to obtain a finely pulverized product (upper classification powder).

  Further, the finely pulverized product (upper limit classification powder) was subjected to lower limit classification (removal of fine powder) with a classifier “TTSP” (manufactured by Hosokawa Micron Corporation) to obtain a toner. Table 2 shows the particle size distribution, true density, and value of the formula (a) of the obtained toner.

Example 4
The same amount as in Example 1 except that the amount of “Carnauba Wax C1” used was changed to 2.0 parts by weight and a twin-screw kneader with a heating temperature in the roll of 100 ° C. was used instead of the open roll type kneader. A toner was obtained. Further, 0.5 part by weight of hydrophobic silica “RY-50” (manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the obtained toner, and externally added with a Henschel mixer.

Example 5
A toner was obtained in the same manner as in Example 1 except that a dispersion separator “DS” (manufactured by Nippon Pneumatic Co., Ltd.) was used as a classifier instead of “TTSP”.

Example 6
A toner was obtained in the same manner as in Example 1 except that a jet mill pulverizer “IDS-5” (manufactured by Nippon Pneumatic Co., Ltd.) was used instead of the counter jet mill “400AFG”.

Comparative Example 1
A toner was obtained in the same manner as in Example 1 except that “R972” was not used during coarse pulverization. Further, 0.5 parts by weight of hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the obtained toner, and externally added with a Henschel mixer.

Comparative Example 2
A toner was obtained in the same manner as in Example 1 except that 4.0 parts by weight of “H3004” (manufactured by Wacker) was used instead of “R972” as the hydrophobic silica.

Comparative Example 3
The amount of “Carnauba wax C1” was changed to 2.0 parts by weight, and “R972” was not used during coarse pulverization. Instead of an open roll type kneader, a twin-screw kneader with an in-roll heating temperature of 100 ° C. A toner was obtained in the same manner as in Example 1 except that was used. Further, 0.5 parts by weight of hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the obtained toner, and externally added with a Henschel mixer.

Test example 1
Whether or not streaks caused by filming have occurred by printing 24000 images with a printing rate of 5% continuously with toner mounted on the "MicroLine 9300PS" (Oki Data Corporation, resolution: 1200dpi x 600dpi) Was visually observed to evaluate filming resistance. In addition, for those in which filming did not occur up to 24,000 sheets, a halftone image was printed after printing 24,000 sheets, the uniformity was visually evaluated, and the solid uniformity was evaluated. The results are shown in Table 2.

  From the above results, the toners obtained in the examples in comparison with the toners obtained in the comparative examples were excellent in filming resistance even in continuous printing, and unevenness was observed in the solid uniformity. Even in such a case, it can be seen that the toner is excellent in durability since it is at a practical level or more.

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

Claims (4)

Step (I) of melt-kneading a raw material containing a binder resin and a colorant, the kneaded product obtained in step (I) is cooled, and coarsely pulverized to a volume-median particle size (D ₅₀ v) of 10 to 1000 μm Step (II), pulverizing the coarsely pulverized product obtained in step (II) in the presence of an external additive having an average particle size of 8 to 50 nm in step (III), and step (III) A method for producing a toner comprising a step (IV) of classifying the obtained finely pulverized product, wherein the obtained toner has a volume median particle size (D ₅₀ v) of 3.5 to 8 μm, and m in the step (III) The total abundance of the types of external additives is represented by the formula (a):

[Where Dt is the volume-median particle size (D ₅₀ v, μm) of the target toner, dn is the average particle size (μm) of the external additive n, ρt is the true density of the toner base particles, and ρn is the external density The true density of additive n, Cn is the weight ratio of external additive n to the coarsely pulverized product (external additive n / coarly pulverized product), and m is an integer of 1 or more.
A toner production method satisfying Standard deviation of the volume particle size distribution of the toner is not more than 1/4 of D ₅₀ v, particle size (1.4 × D ₅₀ v) the content of μm or more particles is not more than 5 vol%, particle size (0.6 × number median particle size (D ₅₀ p)) μm the following method for producing a toner according to claim 1, wherein the content is 5% by number of the particles.   In step (IV), a classification rotor having a drive shaft arranged vertically in the casing as a central axis, and the same drive shaft as the classification rotor as a central axis, and the classification in the classification zone on the outer periphery of the classification rotor The method for producing toner according to claim 1 or 2, wherein the finely pulverized product is classified using a classifier having a stationary spiral guide blade arranged at a distance from the outer periphery of the rotor.   The method for producing a toner according to any one of claims 1 to 3, wherein in step (III), the coarsely pulverized product is finely pulverized using a fluidized bed jet mill.