JP6548555B2 - Method of manufacturing pulverized toner for electrophotography - Google Patents

Description

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

In recent years, high speed and high image quality has been required. In particular, the transferability is largely influenced by the shape of the toner, and is spherical.
As a method of spheroidization, heat treatment or a mechanical crusher is often used. However, in the heat treatment, since the wax bleeds out on the toner surface after the heat treatment, the durability is greatly deteriorated. In a mechanical crusher, it is necessary to increase the number of passes to improve the degree of circularity, and therefore, there is a problem of deterioration in productivity and occurrence of coarse particles in the crusher. Problems remain with toner performance and manufacturing.
Then, in order to solve the subject, the spheroidization processing which uses a batch type surface modification device which can be classified while being spheroidized is known (refer to patent documents 1).

Unexamined-Japanese-Patent No. 2003-262981

  However, in order to increase the degree of circularity in a batch-type apparatus, it is necessary to extend the residence time, which reduces the productivity.

  The present invention relates to a method in which a highly circular pulverized electrophotographic toner can be obtained with high productivity even by using a batch-type surface modifying apparatus.

The present invention
Process 1: A process of melt-kneading a raw material containing a binder resin and a colorant,
Step 2: A step of pulverizing the kneaded material obtained in step 1 to obtain a coarsely pulverized material having a maximum diameter of 2 mm or less,
Step 3: A step of further finely pulverizing the coarsely pulverized material obtained in the step 2 in the presence of 1.5 parts by mass or more and 10 parts by mass or less of inorganic fine particles with respect to 100 parts by mass of the roughly pulverized material
Step 4: A step of classifying the pulverized material obtained in Step 3 and a step of subjecting the classified material obtained in Step 4 to a surface modification treatment There,
The step of surface modification treatment is a step of using a batch-type surface modification device, and the batch-type surface modification device is a classification means for continuously discharging and removing fine powder of a predetermined particle diameter or less to the outside of the device. Surface treatment means using mechanical impact force, and guiding means for partitioning the inside of the apparatus into a first space for introducing the treatment object into the classification means and a second space for introducing the treatment object into the surface treatment means. ,
In the step 5, after the classified product obtained in the step 4 is introduced into the second space and surface modification treatment is carried out, it is introduced into the first space and classification treatment is carried out, and again into the second space It is a process to repeat surface modification treatment and classification treatment by introducing and circulating the first space and the second space.
The present invention relates to a method for producing a pulverized toner for electrophotography.

  According to the method of the present invention, a pulverized toner for electrophotography having a high degree of circularity can be obtained with high productivity even by using a batch-type surface reforming apparatus.

It is a schematic sectional drawing of one embodiment of the surface-modification apparatus used for this invention. It is a top view of one embodiment of the rotary body in FIG. FIG. 6 is a schematic cross-sectional view of a surface modification device used in Comparative Example 1;

In the present invention, inorganic fine particles are added to a roughly pulverized product to a certain extent, and further finely pulverized, and the classified toner particles are surface-treated by a batch-type surface modifying apparatus having a predetermined structure. This is a method of obtaining high toner with high productivity.
In order to efficiently perform spheroidization using a batch-type apparatus that performs surface modification (spheronization) processing while circulating an object in the apparatus, the fluidity of the system is enhanced to circulate toner particles. It is important to increase the speed and increase the number of spheroidizing treatments that the toner particles are subjected to per given time. In the present invention, as described above, the inorganic fine particles are added to the coarsely pulverized product to a certain extent and further finely pulverized and classified in the production process of the toner. The fluidity of the toner particles can be enhanced, and a pulverized toner having a high degree of circularity can be efficiently obtained with a high yield.
Furthermore, the processing capacity can be further enhanced by changing the position of the raw material inlet in the batch surface modification apparatus.

  Step 1 is a step of melt-kneading a raw material containing a binder resin and a colorant.

  Examples of the binder resin include polycondensation resins such as polyester, polyamide and polyester polyamide, vinyl resins such as styrene resin and styrene acrylic resin, epoxy resin, polycarbonate, polyurethane and the like. From the point of view, polyester is preferred.

  The polyester is preferably amorphous from the viewpoint of durability.

  The crystallinity of the resin is represented by the ratio of the softening point to the highest peak temperature of endotherm by differential scanning calorimeter, that is, the crystallinity index defined by the value of [softening point / highest peak temperature of endotherm]. The crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less, and the amorphous resin is Or a resin having a crystallinity index of more than 1.4, preferably more than 1.5, more preferably more than 1.6, or a resin less than 0.6, preferably less than 0.5. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the production conditions (eg, reaction temperature, reaction time, cooling rate) and the like. The highest endothermic peak temperature refers to the temperature of the highest end of the observed endothermic peaks. In a crystalline resin, the highest peak temperature of the endotherm is taken as the melting point.

  The polyester is preferably a polycondensate of a raw material monomer containing an alcohol component containing a dihydric or higher alcohol and a carboxylic acid component containing a dihydric or higher carboxylic acid compound.

  As the alcohol component, from the viewpoint of durability, formula (I):

(Wherein, RO and OR are oxyalkylene groups, R is ethylene and / or propylene groups, x and y indicate the average addition mole number of alkylene oxide, and each is a positive number, and x and y are The sum value is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 4 or less)
The alkylene oxide adduct of bisphenol A represented by is preferred. As the alkylene oxide adduct of bisphenol A represented by the formula (I), a propylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane, ethylene oxide of 2,2-bis (4-hydroxyphenyl) propane An additive etc. are mentioned. It is preferable to use one or more of these.

  The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 70 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably in the alcohol component. It is 100 mol%.

  Other alcohol components include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butene Aliphatic diols such as diol, 1,3-butanediol, neopentyl glycol and the like, alcohols having trivalent or higher such as glycerin and the like can be mentioned.

  On the other hand, as the divalent carboxylic acid compound in the carboxylic acid component, an aromatic dicarboxylic acid compound is preferable from the viewpoint of durability. In addition, from the viewpoint of low temperature fixability, aliphatic dicarboxylic acid compounds are preferable.

  Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid and terephthalic acid; anhydrides of these acids or alkyl (C1-C3) esters of these acids, among which terephthalic acid is preferred. Alternatively, isophthalic acid is preferred, and terephthalic acid is more preferred. These may be used alone or in combination of two or more. In the present invention, carboxylic acid compounds include not only free acids but also anhydrides which are decomposed during the reaction to form acids, or alkyl esters having 1 to 3 carbon atoms.

  The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 65 mol% or more, and preferably 85 mol% or less. More preferably, it is 75 mol% or less.

  Examples of aliphatic dicarboxylic acid compounds include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, dodecenyl succinic acid, octyl succinic acid, etc. Aliphatic dicarboxylic acids such as succinic acid substituted with an alkyl group or an alkenyl group having 2 to 20 carbon atoms; anhydrides of these acids or alkyl (carbon atoms of 1 to 3) esters of these acids, and the like. These may be used alone or in combination of two or more.

  The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is preferably 2 mol% or more, more preferably 4 mol% or more, and from the viewpoint of storage stability, preferably 10 mol% or less, more preferably Is 8 mol% or less.

  The carboxylic acid component preferably contains a trivalent or higher carboxylic acid compound from the viewpoint of offset resistance.

  Examples of trivalent or higher carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid or their acid anhydrides, lower alkyl (carbon Formulas 1-3) ester etc. are mentioned, Among these, a trimellitic acid type compound is preferable.

  The content of the trivalent or higher carboxylic acid compound, preferably the trimellitic acid compound, is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% in the carboxylic acid component. From the viewpoint of low-temperature fixability, it is preferably 40 mol% or less, more preferably 35 mol% or less, and still more preferably 30 mol% or less.

  A monohydric alcohol may be suitably contained in the alcohol component, and a monobasic carboxylic acid compound may be suitably contained in the carboxylic acid component from the viewpoint of molecular weight adjustment.

  The equivalent ratio of the carboxylic acid component to the alcohol component (COOH group / OH group) is preferably 0.7 or more, more preferably 0.8 or more, and preferably 1.3 or less, more preferably 1.2 or less.

  The polycondensation of the alcohol component and the carboxylic acid component is carried out, for example, in an inert gas atmosphere, if necessary, in the presence of an esterification catalyst, an esterification cocatalyst, a polymerization inhibitor, etc., at about 180 ° C. to 250 ° C. Can be done at a temperature of Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bis triethanolaminate. Examples of the esterification promoter include gallic acid and the like. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1 part by mass or less, based on 100 parts by mass of the total of the alcohol component and the carboxylic acid component. Preferably, it is 0.6 parts by mass or less. The amount of the esterification promoter is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, based on 100 parts by mass of the total of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 parts by mass or less.

  The softening point of the polyester is preferably 90 ° C. or more, more preferably 100 ° C. or more, still more preferably 105 ° C. or more, from the viewpoint of improving the durability of the toner, and from the viewpoint of improving the low temperature fixability of the toner. Preferably it is 150 degrees C or less, More preferably, it is 140 degrees C or less, More preferably, it is 130 degrees C or less. When 2 or more types of polyesters are contained, it is preferable that the weighted average value of a softening point exists in the said range.

  The glass transition temperature of the polyester is preferably 50 ° C. or more, more preferably 55 ° C. or more, still more preferably 60 ° C. or more, from the viewpoint of improving the durability of the toner, and the viewpoint of improving the low temperature fixability of the toner The temperature is preferably 80 ° C. or less, more preferably 75 ° C. or less, still more preferably 70 ° C. or less.

  The acid value of the polyester is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less, still more preferably 20 mgKOH / g or less, and preferably 1 mg KOH, from the viewpoint of improving the environmental stability of the charge amount of the toner. / g or more, more preferably 2 mg KOH / g or more.

  The content of polyester in the binder resin is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 100% by mass.

  As colorants, all dyes, pigments and the like used as colorants for toners can be used, and 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. The toner of the present invention may be either black toner or color toner.

  The content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, with respect to 100 parts by mass of the binder resin, from the viewpoint of improving the image density and low temperature fixability of the toner. The amount is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less.

  The raw material may contain a release agent, a charge control agent and the like in addition to the binder resin and the colorant.

  As a mold release agent, aliphatic hydrocarbon wax such as polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax, microcrystalline wax, paraffin wax, Fischer Tropsch wax, Sazol wax or its oxide, carnauba wax, Montan wax or their deacidified waxes, ester waxes such as fatty acid ester waxes, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like can be mentioned, and these can be used alone or in combination of two or more .

  The melting point of the releasing agent is preferably 60 ° C. or more, more preferably 70 ° C. or more from the viewpoint of transferability of the toner, and preferably 160 ° C. or less, more preferably 140 ° C. from the viewpoint of low temperature fixability. The temperature is more preferably 130 ° C. or less, further preferably 120 ° C. or less.

  The content of the releasing agent is preferably 0.4 parts by mass or more, more preferably 100 parts by mass of the binder resin, from the viewpoints of low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin. The amount is preferably 0.8 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 9 parts by mass or less.

  The charge control agent is not particularly limited, and may contain any of a positively chargeable charge control agent and a negatively chargeable charge control agent.

  As positively chargeable charge control agents, nigrosine dyes such as "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", "Bontron N-04", "Bontron N-07" “Bontron N-09”, “Bontron N-11” (all, manufactured by Orient Chemical Industries Ltd.), etc .; Triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, eg, "Bontron P-51" (manufactured by Orient Chemical Industry Co., Ltd.), cetyltrimethyl ammonium bromide, "COPY CHARGE PX VP 435" (manufactured by Clariant Co., Ltd.), etc .; Polyamine resin, such as "AFP-B" Imidazole derivatives, such as “PLZ-2001”, “PLZ-8001” (above, made by Shikoku Kasei Kogyo Co., Ltd.), etc .; styrene-acrylic resins, such as “FCA-701PT” (Fujikura Kasei Co., Ltd.) ), And the like.

  In addition, as a negatively chargeable charge control agent, metal-containing azo dyes such as "VALIFAST BLACK 3804", "BONTRON S-31", "BONTRON S-32", "BONTRON S-34", "BONTRON S-36" (Above, made by Orient Chemical Industry Co., Ltd.), “Eisen spirone black TRH”, “T-77” (made by Hodogaya Chemical Industry Co., Ltd.), etc .; metal compounds of benzyl acid compounds, for example, “LR- 147 "," LR-297 "(above, manufactured by Nippon Carlit Co., Ltd., etc.); metal compounds of salicylic acid compounds, for example," Bontron E-81 "," Bontron E-84 "," Bontron E-88 "," Bontron E-304 "(above, made by Orient Chemical Industry Co., Ltd.)," TN-105 "(made by Hodogaya Chemical Co., Ltd.), etc .; copper phthalocyanine dye; quaternary ammonium salt, eg," COPY CHARGE NX VP434 " (Manufactured by Clariant), nitroimidazole derivatives, etc .; organic gold And compounds of the genus.

  The content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 15 parts by mass, with respect to 100 parts by mass of the binder resin, from the viewpoint of charging stability of the toner. It is preferably at most 10 parts by mass, more preferably at most 5 parts by mass, and still more preferably at most 3 parts by mass.

  Furthermore, additives such as magnetic powder, fluidity improver, conductivity adjuster, reinforcing filler such as fibrous substance, antioxidant, anti-aging agent, cleanability improver, etc. are appropriately used as the raw material. It is also good.

  In step 1, the raw materials to be subjected to the melt-kneading may be subjected to kneading at one time or may be divided and subjected to kneading, but after being mixed in advance by a mixer such as a Henschel mixer or a ball mill, supplied to the kneader Is preferred.

  Kneading in step 1 or step 2 can be carried out using a known kneader such as a closed-type kneader, a single-screw or twin-screw extruder, or an open roll kneader.

  The resulting kneaded product is suitably cooled until it reaches a crushable hardness, and crushed in step 2. Here, cooling means cooling a kneaded material to 0 degreeC-50 degreeC, or cooling to below the glass transition temperature of the binder resin in a kneaded material.

  Step 2 is a step of pulverizing the kneaded material obtained in step 1 to obtain a coarsely pulverized material having a maximum diameter of 2 mm or less. Hereinafter, the pulverization in step 2 is also referred to as coarse pulverization.

  As a grinder used for coarse grinding, a hammer mill, an atomizer, Rotoplex, etc. may be mentioned.

  The kneaded material obtained in step 1 is appropriately coarsely crushed until the particle size becomes about 0.05 mm or more and 2 mm or less, and then passed through a sieve with an opening of 2 mm, and the crushed material passing through the sieve has a maximum diameter of 2 mm Used in step 3 as a coarsely pulverized material.

  Step 3 is a step of further pulverizing the roughly pulverized product obtained in step 2 in the presence of inorganic fine particles.

  Inorganic fine particles include inorganic fine particles such as silicon dioxide (silica), titanium dioxide, aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, tin oxide and the like, and among these, chargeability is imparted From the viewpoint of the above, silica or titanium dioxide is preferable, silica is more preferable, and hydrophobicized hydrophobic silica is more preferable. These may be used alone or in combination of two or more.

  Examples of hydrophobizing agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), methyltriethoxysilane, etc. Be

  The number average particle diameter of the inorganic fine particles is preferably 6 nm or more from the viewpoint of durability, and is preferably 40 nm or less, more preferably 30 nm or less from the viewpoint of fluidity.

  The amount of the inorganic fine particles used in step 3 is 1.5 parts by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass from the viewpoint of fluidity with respect to 100 parts by mass of the roughly pulverized product obtained in step 2 From the viewpoint of fixability, the amount is 10 parts by mass or less, preferably 8 parts by mass or less, and more preferably 6 parts by mass or less.

  In the step 3, preferably, the coarsely pulverized product obtained in the step 2 and the inorganic fine particles are mixed in advance using a mixer such as a Henschel mixer, and then finely pulverized.

  As a pulverizer used for pulverization, a fluidized bed jet mill, an air jet mill, a mechanical mill, etc. may be mentioned, and among these, a fluidized bed jet mill or an air jet mill is preferable, and a fluidity viewpoint Therefore, a fluidized bed jet mill is more preferable. A fluidized bed jet mill having at least a grinding chamber in which a plurality of jet nozzles are disposed to face the lower portion is more preferable because the fluidity is easily maintained because the toner is crushed by collision of toners.

  In the fluidized bed jet mill, a high velocity gas jet from a jet nozzle forms a fluidized bed of particles supplied in the pulverizing vessel, and particle acceleration and mutual collision are repeated in the fluidized bed. It has a structure / principle in which particles are pulverized.

  In the fluidized bed jet mill having the above structure, the number of jet nozzles is not particularly limited, but from the viewpoint of balance of air volume, flow rate, flow velocity, collision efficiency of particles, etc., plural, preferably 3 to 4 jet nozzles Preferably, they are disposed to face each other.

  Furthermore, in the upper part of the grinding chamber, a classification rotor may be provided which collects particles of small diameter, which are reduced in diameter by grinding and which have increased diameter. The particle size distribution can be easily adjusted by the number of rotations of the classification rotor. Classification with the classification rotor gives a pulverized material (upper limit classified powder) from which coarse powder has been removed.

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

  As a specific example of a fluid bed type jet mill provided with a plurality of jet nozzles and further having a classification rotor, pulverizers disclosed in Japanese Patent Application Laid-Open Nos. 60-166547 and 2002-35631 can be mentioned.

  Moreover, as a commercial item of a fluid bed type jet mill suitably used in this invention, the "TFG" series made from Hosokawa Micron Ltd., "AFG" series etc. are mentioned.

  The degree of pulverization is preferably adjusted appropriately according to the desired toner particle size, but the coarsely pulverized product obtained in step 2 is suitably pulverized to a predetermined particle size and then finely pulverized. It is preferable to use as a substance in step 4.

  Step 4 is a step of classifying the finely pulverized material obtained in step 3.

  Examples of classifiers used for classification include pneumatic classifiers, inertial classifiers, and sieve classifiers.

  Step 5 is a step of subjecting the fraction obtained in Step 4 to a surface modification treatment using a batch surface modification device, and such batch type surface modification device uses fine powder having a predetermined particle diameter or less. Classification means for continuously discharging and removing out of the apparatus, surface treatment means using mechanical impact force, and first space for introducing an object to the classification means and second for introducing the object to the surface treatment means It is an apparatus provided with the guide means which divides the inside of an apparatus into space. In step 5, the classified product obtained in step 4 is introduced into the second space and subjected to surface modification treatment, and then introduced into the first space and subjected to classification treatment, again into the second space. The surface modification treatment and the classification treatment are repeated by introducing and circulating the first space and the second space.

  The surface modification treatment using the batch type surface modification apparatus will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a surface modification apparatus used in the present invention, and FIG. 2 shows an example of a top view of a rotating body rotating at high speed in FIG.

The surface modification apparatus shown in FIG.
Casing 13,
A jacket (not shown) through which cooling water or antifreeze can flow
A plurality of square blocks 10 (may be cylindrical pins) on the upper surface mounted in the casing 13 and mounted on the central rotation axis, which are surface treatment means, on a disk rotating at high speed Distributed rotor 6, which is a rotating body
Liner 4 (fixed body) provided with a large number of grooves on the surface arranged with a constant spacing on the outer periphery of the dispersion rotor 6 (the grooves on the surface of the liner may be omitted)
A classification rotor 1, which is a means for classifying a surface-modified object to a predetermined particle size,
Fine powder discharge port 2 for discharging and removing fine powder of a predetermined particle size or less sorted by a classification rotor,
Cold air inlet 5 for introducing cold air,
A raw material supply port 3 for introducing an object to be treated into the second space 12;
A discharge valve 8 installed so as to be able to open and close so that the surface modification time can be freely adjusted.
A powder discharge port 7 for discharging the powder after processing, and a space between a classification zone and a surface modification zone in the apparatus, a first space 11 for introducing an object to be treated into the classification rotor 1 And a cylindrical guide ring (guide plate) 9 as a guiding means for dividing the object to be treated into a second space for introducing the object into the dispersing rotor 6.
And consists of The classification rotor 1 and the periphery of the rotor are classification zones, and the gap between the dispersion rotor 6 and the liner 4 is a surface modification zone.

  The installation direction of the classification rotor 1 may be horizontal as well as vertical as shown in FIG. Further, the number of classification rotors 1 may be not only a single as shown in FIG. 1 but also a plurality.

  Specifically explaining the steps of surface modification treatment and classification treatment in the surface modification apparatus having the above-mentioned configuration, when a fixed amount of classified material is fed from the raw material supply port 3 with the discharge valve 8 closed, it is charged. The classified matter is first drawn by a blower (not shown), introduced into the second space, and then generated by the dispersion rotor 6 along the inner periphery (the second space 12) of the guide ring (guide plate) 9 The circulation flow is led to the surface reforming zone. The fraction introduced to the surface modification zone is subjected to mechanical impact between the dispersing rotor 6 and the liner 4 to be surface modified. The surface-modified surface-modified particles are guided to the classification zone along the outer periphery (first space 11) of the guide ring 9 by the cold air passing through the inside of the machine. The surface modified particles are classified by the classification rotor 1 into fine powder of a predetermined particle size or less and coarse powder of a predetermined particle size or more, the fine powder is discharged to the outside of the machine, and the coarse powder rides on the circulating flow, It is returned to the space 12 and repeatedly subjected to surface modification action in the surface modification zone. After a predetermined time has elapsed, the discharge valve 8 is opened to recover surface-modified particles from the powder discharge port 7.

By using a surface modification device capable of repeating surface modification treatment while discharging and removing fine powder of a predetermined particle size or less, surface modification is performed with good yield while preventing an increase in the amount of powder during surface modification. Processing can be performed.
In addition, the retention time of the toner in the apparatus can be adjusted by arbitrarily setting the time for opening the discharge valve, the surface shape of the toner can be arbitrarily controlled, and the toner having high circularity and excellent transferability can be obtained. be able to.

Furthermore, in the present invention, the material to be treated introduced into the surface modification apparatus (the classified product obtained in step 4) is introduced not to the first space but to the second space, ie, in the above configuration, the raw material One feature is that the supply port 3 is provided to introduce the object to the second space 12.
The throughput per hour can be increased by first introducing the fraction obtained in step 4 into the second space, and then repeating the surface modification treatment and the classification treatment. This is because by first passing through the surface modification zone, the dispersibility of the powder is improved and classification can be performed efficiently.

  The surface shape of the toner depends on the residence time of the toner in the surface modification device. That is, in order to control the surface shape of the toner, it is important to control the circulation time of the toner in the surface modification device. In the present invention, the surface modification device used in the surface modification step is a batch type surface modification device as shown in FIG. By controlling the peripheral speed, the distance between the dispersion rotor and the liner, and the distance between the guide ring and the dispersion rotor to an appropriate state, it is possible to prevent an increase in fine powder at the time of surface modification, and to The residence time can be controlled, and the surface shape of the toner can be arbitrarily controlled. In addition, since the classification rotor that classifies the surface-modified toner to a predetermined particle size is built in, by controlling the rotational peripheral speed of the classification rotor to an appropriate state, the fine powder below the predetermined particles continues to the outside of the apparatus Since the coarse powder can be again surface-reformed, it is possible to obtain surface-modified particles from which fine particles of a predetermined particle size or less have been removed.

  The circulation time for repeating the surface modification treatment and the classification treatment in the surface modification device is preferably 5 seconds or more, more preferably 10 seconds or more from the viewpoint of obtaining the surface modification effect, and the surface modification time is long It is preferably 720 seconds or less, more preferably 600 seconds or less, from the viewpoint of avoiding the surface deterioration of the toner due to the heat generated at the time of surface modification, the occurrence of in-machine fusion, and the decrease in processing capacity.

  It is preferable to control the temperature in the apparatus by sending cold air or passing a coolant through the jacket to prevent surface deterioration of the toner due to heat generated during surface modification and in-machine fusion. .

  In the present invention, the average degree of circularity is used as an indicator of the degree of surface modification (spheroidization) of the surface modified particles.

  The average degree of circularity of the surface modified particles obtained by the step 5 is preferably 0.945 or more, more preferably 0.955 or more from the viewpoint of transferability. The average circularity is an index showing the degree of unevenness of the surface modified particles, and the circularity when the toner is completely spherical, that is, the upper limit value of the average circularity is 1.000. On the other hand, the larger the unevenness of the particle surface, the smaller the value of circularity.

In the present invention, in order to further improve the transferability,
Step 6: It is preferable to include the step of mixing the surface modified particles obtained in Step 5 with an external additive.

  The external additive may be the same as or different from the inorganic fine particles used in Step 3. For example, inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide and zinc oxide, and organic fine particles such as resin particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles can be mentioned, and two or more kinds are used in combination It may be Among these, silica is preferable, and from the viewpoint of the transferability of the toner, hydrophobic silica treated with hydrophobic treatment is more preferable.

  Examples of hydrophobizing agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), methyltriethoxysilane, etc. Be

  The number average particle diameter of the external additive is preferably 6 nm or more, more preferably 8 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, from the viewpoints of chargeability, fluidity, and transferability of the toner. More preferably, it is 150 nm or less.

  The amount of the external additive used is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and further preferably 100 parts by mass of the surface-modified particles from the viewpoints of chargeability, fluidity, and transferability of the toner. Is 0.3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

  A mixer such as a Henschel mixer can be used to mix the surface modified particles obtained in step 5 with the external additive.

The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In the present specification, the volume median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by volume fraction is 50% as calculated from the smaller particle size. When the toner is treated with an external additive, the volume median particle size of the toner particles before being treated with the external additive is taken as the volume median particle size of the toner.

  The toner of the present invention can be used as a one-component developing toner or as a two-component developer mixed with a carrier.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. Physical properties of the resin and the like were measured by the following methods.

[Softening point of resin]
Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating a 1 g sample at a heating rate of 6 ° C./min, a load of 1.96 MPa is applied by a plunger, diameter 1 mm, length 1 mm Push out of the nozzle. The plunger drop amount of the flow tester is plotted against the temperature, and the temperature at which half of the sample flowed out is taken as the softening point.

[Maximum peak temperature of endotherm of resin]
Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), measure 0.01 to 0.02 g of a sample on an aluminum pan and measure 0 ° C at a temperature decrease rate of 10 ° C / min from room temperature. Cool to 0 C and hold at 0 C for 1 minute. Thereafter, measurement is performed at a temperature rising rate of 10 ° C./min. Of the observed endothermic peaks, the temperature of the peak located on the highest temperature side is taken as the highest endothermic peak temperature.

[Glass transition temperature of resin]
Using a differential scanning calorimeter “DSC Q20” (manufactured by TA Instruments Japan Co., Ltd.), measure 0.01 to 0.02 g of a sample in an aluminum pan, raise the temperature to 200 ° C., and lower the temperature from that temperature Cool to 0 ° C. at a rate of 10 ° C./min. Next, the sample is heated at a temperature rising rate of 10 ° C./min to measure an endothermic peak. The temperature at the intersection of the extension of the baseline below the highest endothermic peak temperature and the tangent showing the maximum slope from the rising portion of the peak to the peak of the peak is taken as the glass transition temperature.

[Acid value of resin]
It measures based on the method of JISK0070. However, only the measurement solvent is changed to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)) from a mixed solvent of ethanol and ether defined in JIS K0070.

Melting point of mold release agent
Using a differential scanning calorimeter “DSC Q20” (manufactured by TA Instruments Japan Co., Ltd.), measure 0.01 to 0.02 g of a sample on an aluminum pan, and heat up to 200 ° C. at a heating rate of 10 ° C./min. The temperature is raised and cooled from the temperature to -10 ° C. at a temperature decrease rate of 5 ° C./min. Next, the sample is heated to 180 ° C. at a heating rate of 10 ° C./min and measured. The highest endothermic peak temperature observed from the melting endothermic curve obtained there is taken as the melting point of the release agent.

[Number Average Particle Size of Inorganic Fine Particles and External Additives Used in Step 3]
The particle size (average value of the major axis and the minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the average value thereof is defined as the number average particle size.

[Toner volume median particle size (D ₅₀ ) and content of particles having a particle size of 5 μm or less]
Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter Co., Ltd.)
Aperture diameter: 100 μm
Analysis software: Coulter multisizer Accucomp version 1.19 (manufactured by Beckman Coulter Co., Ltd.)
Electrolyte: Isoton II (manufactured by Beckman Coulter Co., Ltd.)
Dispersion solution: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB (glyphin): 13.6) dissolved in electrolyte to adjust to 5% by mass Dispersion conditions: 10 mg of measurement sample in 5 mL of the dispersion Is added, and dispersed for 1 minute with an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W), and then 25 mL of the electrolyte is added, and further, to the ultrasonic disperser Disperse for 1 minute to prepare a sample dispersion.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte so that the particle size of 30,000 particles can be measured in 20 seconds, 30,000 particles are measured, and the volume is determined from the particle size distribution. Determine the median particle size (D ₅₀ ).

[Average circularity of toner]
Measuring machine: FPIA-3000 (made by Sysmex Corporation)
Standard unit (10x objective lens)
Measurement mode HPF mode dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB 13.6) 5% by mass Electrolytic dispersion conditions: 10 mg of the measurement sample is added to 10 ml of the dispersion, and an ultrasonic dispersion machine is used. Disperse for 1 minute, then add 10 ml of distilled water, and further disperse for 2 minutes with an ultrasonic disperser.
Measurement conditions: The circularity of the toner dispersed in the dispersion liquid is measured at 20 ° C. at a density that results in a particle density of 1800 to 2200, and a number average value is determined.

Resin Production Example 1 [Resin A]
Raw material monomers and esterification catalyst other than trimellitic anhydride shown in Table 1 are put in a 10 L four-necked flask equipped with a nitrogen introducing pipe, a dehydrating pipe, a stirrer and a thermocouple, and heated to 200 ° C. under a nitrogen atmosphere. The temperature was raised and reacted for 6 hours. Further, after raising the temperature to 210 ° C., trimellitic anhydride is added, reacted at normal pressure (101.3 kPa) for 1 hour, and further reacted at 40 kPa until the desired softening point is reached to obtain amorphous polyester Obtained. Physical properties of the obtained resin are shown in Table 1.

Examples 1 to 8, 11 and Comparative Examples 3 to 6
[Step 1]
94 parts by mass of resin A, 1.0 parts by mass of negatively chargeable charge control agent "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), and carbon black "MOGUL-L" (manufactured by Cabot Specialty Chemicals Inc.) ) After stirring and mixing 4.0 parts by mass and 1.0 part by mass of a release agent "SP-105" (Fisher Hiroyuki Co., Ltd., Fischer Tropsch wax, melting point: 105 ° C) with a Henschel mixer for 1 minute, the conditions shown below It melt-kneaded.

  A co-rotating twin-screw extruder PCM-30 (manufactured by Ikegai Co., Ltd.) was used. The operating conditions of the co-rotating twin-screw extruder were a barrel set temperature of 100 ° C., a shaft rotational speed of 200 r / min (circumferential shaft circumferential speed of 0.30 m / sec), and a mixture supply speed of 10 kg / h. Then, the obtained kneaded material was cooled by a cooling roll.

[Step 2]
The crude product was roughly crushed with Alpineroth Plex (manufactured by Hosokawa Micron Ltd.), passed through a sieve with an opening of 2 mm to obtain a coarsely crushed product having a maximum diameter of 2 mm or less.

[Step 3]
100 parts by mass of the obtained roughly pulverized product and the inorganic fine particles shown in Table 2 were mixed for 2 minutes with a Henschel mixer. The resulting mixture was pulverized using a fluid bed jet mill "400 type TFG" (manufactured by Hosokawa Micron Corporation).

[Step 4]
Next, classification was performed using a rotor type classifier “TTSP classifier” (manufactured by Hosokawa Micron Corporation) so that the volume median particle size (D ₅₀ ) would be 6.0 μm.

[Step 5]
The surface modification treatment of the obtained classified material was performed using a batch-type surface modification device.
As a batch-type surface reforming apparatus, an apparatus was used in which the raw material inlet of the Faculty (manufactured by Hosokawa Micron Corporation) was modified so as to introduce an object to be treated into the second space. In the surface reforming apparatus, the rotation number of the dispersion rotor is 5100 r / min, the rotation number of the classification rotor is 5200 r / min, the air volume is 20 Nm ³ , and the conditions of 12 hammers (square block) are fixed. And in Comparative Examples 3, 4 and 6, the target circularity was set to 0.960 ± 0.003, and the surface modification treatment was performed while changing the input amount and the stirring time.
On the other hand, in Example 11 and Comparative Example 5, the surface modification was performed under the condition that the same performance as in Example 1 was obtained.

[Step 6]
100 parts by mass of the surface-modified particles obtained and, as an external additive, hydrophobic silica “RY50” (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: silicone oil, number average particle diameter: 40 nm) 1.0 parts by mass, And 0.5 parts by mass of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobization treatment agent: DMDS, number average particle diameter: 16 nm) with a Henschel mixer for 3 minutes to obtain a toner.

Example 9
1.0 parts by mass of "LR-147" (manufactured by Nippon Carlit Co., Ltd.) instead of "T-77" as a negatively chargeable charge control agent, and copper phthalocyanine pigment "ECB-301" (large daily refinement) instead of carbon black A toner was obtained in the same manner as in Example 2 except that 4.0 parts by mass of Kogyo Co., Ltd. was used.

Example 10
In Steps 3 and 4, using the IDS pulverizer / classifier (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), which is a pneumatic jet mill, instead of the fluidized bed jet mill and the TTSP classifier, the volume median particle size ( A toner was obtained in the same manner as in Example 2 except that pulverization and classification were performed so that D ₅₀ ) would be 6.0 μm.

Comparative Example 1
The same process as in Example 1 was carried out except that a device for introducing the object to be treated into the first space was used as the surface modification device used in step 5 without modifying the raw material inlet as shown in FIG. I got a toner.

Comparative example 2
A toner was obtained in the same manner as in Example 2 except that the surface modification step of Step 5 was not performed.

[Capability ratio]
In the process 5 of Examples 1 to 10 and Comparative Examples 1, 3, 4 and 6, the processing capacity is calculated from the conditions set for aiming at the target circularity (0.960 ± 0.003), and the processing capacity of Example 1 is set to 1. Table 2 shows the performance ratios in each of the Examples and Comparative Examples.
In Example 11 and Comparative Example 5, the target circularity was not set, and when the surface modification process was attempted with the same processing ability as in Example 1, it was confirmed what degree of circularity toner could be obtained. .
In addition, since the used surface-modification apparatus is a batch type, the processing capacity is determined by the input amount to the apparatus and the circulation time in the apparatus. For example, in the case where 1.0 kg of the object to be processed is introduced, the circulation time is 60 seconds in the apparatus, and the total time for the input and output of the object to be processed is 20 seconds, the throughput per hour is X 60) / (60 + 20) = 45 kg.
The larger the capacity ratio, that is, the higher the processing capacity, the toner having a predetermined degree of circularity can be obtained in a short time, which indicates that the productivity is high.

[Classification yield]
The classification yield is shown in Table 2. The classification yield is the ratio of the amount (X) of the classified material input to the surface reforming device to the amount (Y) of the surface modifying particles recovered from the surface reforming device in step 5, and is calculated by the following equation .
Classification yield (%) = Y / X × 100
The higher the classification yield, the higher the amount obtained per hour, and the higher the productivity.

[Transferability]
Toner was mounted on "MICROLINE VINCI C711dn" manufactured by Oki Data Co., Ltd., and a solid image (25 cm x 18 cm) was printed on the entire surface. The optical reflection density of the solid image was measured using a reflection densitometer (RD-915, manufactured by Gretag Macbeth Co., Ltd.), and the developing bias was changed so that the image density was 1.4 to 1.5. Thereafter, characters having a font size of 8 pt were printed, and the obtained printed matter was observed with an optical microscope to evaluate transferability according to the following evaluation criteria. The results are shown in Table 2.

〔Evaluation criteria〕
A: There is no dropout B: There is a dropout a little C: Dropout a little noticeable D: A dropout stands out

From the above results, it can be seen that in Examples 1 to 11, a toner having a high degree of circularity and good transferability is obtained with high productivity.
On the other hand, in Comparative Example 1 in which the object to be treated was first introduced into the first space in the step 5, it is understood that the processing capacity is low and the productivity is lacking.
In Comparative Example 2 in which Step 5 is not performed, it is understood that the circularity of the toner is as low as 0.950, and the transferability is lacking.
In the comparative example in which the amount of the inorganic fine particles used in step 3 is small, the productivity is low to obtain a toner having a high degree of circularity (Comparative Examples 3, 4 and 6). On the other hand, as described above, it can be seen that when maintaining the productivity under the condition where the amount of the inorganic fine particles is small, a toner having a high degree of circularity can not be obtained (Comparative Example 5).

  The pulverized toner for electrophotography obtained by the method of the present invention is suitably used, for example, for developing a latent image formed by an electrostatic charge image developing method, an electrostatic recording method, an electrostatic printing method or the like.

DESCRIPTION OF SYMBOLS 1 Classification rotor 2 Fine powder discharge port 3 Raw material supply port 4 Liner 5 Cold air introduction port 6 Dispersion rotor 7 Powder discharge port 8 Discharge valve 9 Guide ring 10 Square block 11 First space 12 Second space 13 Casing

Claims (5)

Process 1: A process of melt-kneading a raw material containing a binder resin and a colorant,
Step 2: A step of pulverizing the kneaded material obtained in step 1 to obtain a coarsely pulverized material having a maximum diameter of 2 mm or less,
Step 3: A step of further finely pulverizing the coarsely pulverized material obtained in the step 2 in the presence of 1.5 parts by mass or more and 10 parts by mass or less of inorganic fine particles with respect to 100 parts by mass of the roughly pulverized material
Step 4: A step of classifying the pulverized material obtained in Step 3 and a step of subjecting the classified material obtained in Step 4 to a surface modification treatment There,
The step of surface modification treatment is a step of using a batch type surface modification device, and the batch type surface modification device is a classification means for continuously discharging and removing fine powder having a predetermined particle diameter or less to the outside of the device. Surface treatment means using mechanical impact force, and guiding means for partitioning the inside of the apparatus into a first space for introducing the treatment object into the classification means and a second space for introducing the treatment object into the surface treatment means. ,
In the step 5, after the classified product obtained in the step 4 is introduced into the second space and surface modification treatment is carried out, it is introduced into the first space and classification treatment is carried out, and again into the second space It is a process to repeat surface modification treatment and classification treatment by introducing and circulating the first space and the second space.
Process for producing pulverized toner for electrophotography.   The method according to claim 1, wherein the milling in step 3 is carried out using a fluid bed jet mill.   The manufacturing method according to claim 2, wherein the fluidized bed jet mill at least has a grinding chamber in which a plurality of jet nozzles are disposed to face each other in the lower part. further,
Process 6: The manufacturing method in any one of Claims 1-3 including the process of mixing the surface modification particle | grains obtained at the process 5 with an external additive.   The method according to any one of claims 1 to 4, wherein the number average particle diameter of the inorganic fine particles is 6 nm or more and 40 nm or less.

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