JP2023118522A - Toner and manufacturing method therefor - Google Patents

Abstract

To provide a toner which offers superior low-temperature fixability, storage stability and light resistance and is capable of suppressing blocking and filming, and to provide a manufacturing method therefor.SOLUTION: A toner provided herein has an external additive adhered to surfaces of toner particles. The external additive contains fine wax particles having hydrophobized inorganic fine particles adhered to surfaces thereof. Primary particles of the fine wax particles have volume-based median diameter in a range of 70 to 100 nm, inclusive.SELECTED DRAWING: Figure 2

Description

The present invention relates to a toner used in an electrophotographic system, an electrostatic recording system, an electrostatic printing system and a toner jet system, and a method for producing the same.

2. Description of the Related Art In recent years, image forming apparatuses such as full-color printers, full-color copiers, and full-color multifunction machines have been required to have high developability capable of stably outputting high-quality printed matter. In addition, the diversification of recording media used in image forming apparatuses has progressed, and many papers with low surface smoothness have been used. In the case of such paper, the toner is difficult to be transferred to the recessed portions of the paper surface, so image defects such as images with low in-plane uniformity are likely to occur.

Under these circumstances, in order to realize an image forming apparatus that has high transferability to a recording medium and can obtain excellent image quality, hot air treatment is applied to pulverized toner with many unevenness to remove toner particles (toner cores). There has been provided a toner with improved transfer efficiency by deforming the shape into a spherical shape (thermal spheroidization). However, since the wax used as a release agent bleeds out during thermal spheroidization (see FIG. 1), there is a problem that the wax adheres to the photosensitive drum (filming). Also, in order to prevent this, when the amount of wax added is reduced, or when wax with a melting point as high as possible is used, there is a problem that the releasability for high-speed printing is insufficient.

As a technique for solving this problem, for example, Japanese Patent Application Laid-Open No. 5-323654 (Patent Document 1) discloses wax microparticles having a volume average particle size of 0.4 μm to 1.6 μm and non-magnetic particles having a volume average particle size of 32 nm to 128 nm. A toner has been proposed in which the non-magnetic particles are attached to the surface of the wax fine particles by applying mechanical pressure to the particles, and the wax fine particles are externally added to the toner particles (attached to the toner particle surfaces).

JP-A-5-323654

However, with the trend toward energy saving in image forming apparatuses, the melting point of wax used as a release agent is being lowered in order to fix toner at a lower temperature. It is impossible to reduce the low-melting-point wax to a volume-average particle size of 0.4 μm to 1.6 μm. In addition, while the particle size of toner particles is becoming smaller, the use of the structure of Patent Document 1 causes a problem that the flowability is deteriorated and the developability is deteriorated.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide excellent low-temperature fixability, storage stability, and light resistance even when pulverized toner particles are spheroidized by hot air treatment. Another object of the present invention is to provide a toner capable of suppressing blocking and filming, and a method for producing the same.

As a result of diligent research to solve the above problems, the inventors of the present invention have found that even when the toner particles are thermally spherical, the toner particles are formed by using, as an external additive, an inorganic fine particle coated with finely divided wax. The inventors have found that a wax with a low melting point can be used, and have completed the present invention.

That is, the invention made to solve the above problems is a toner in which an external additive is attached to the surface of toner particles, wherein the external additive contains wax fine particles having hydrophobic inorganic fine particles attached to the surface. 2. The toner is characterized in that the volume-based median diameter of the primary particles of the wax fine particles is 70 nm or more and 100 nm or less. In the following description, "wax microparticles having hydrophobic inorganic microparticles adhered to their surfaces" is also referred to as "external wax additive".

Another invention, which has been made to solve the above-mentioned problems, is a method for producing the above-mentioned toner, comprising: a wax finely pulverizing step of obtaining a finely pulverized wax slurry by using a bead mill for wax; a coating step of adding hydrophobized inorganic fine particles to the wax slurry obtained in the pulverizing step and stirring to obtain a wax slurry in which the inorganic fine particles are attached to the surface of the wax; A drying step of drying the wax slurry to obtain wax microparticles having hydrophobic inorganic microparticles attached to the surface thereof, and mixing the wax microparticles obtained in the drying step with the toner particles to form the toner particles on the surfaces of the toner particles. and an external addition step of obtaining a toner to which the wax fine particles are adhered, and a wet bead mill is used in the wax pulverization step.

According to the present invention, it is possible to provide a toner which is excellent in low-temperature fixability, storage stability, and light resistance, and which can suppress blocking and filming, and a method for producing the same.

FIG. 2 is a conceptual diagram schematically showing pulverized toner particles containing low-melting-point wax (left side) and thermally spherical toner particles (right side) obtained by spheroidizing the pulverized toner particles by hot air treatment. FIG. 2 is a conceptual diagram schematically showing wax microparticles (left side) and an external additive (right side) according to the present embodiment, in which inorganic microparticles hydrophobized with respect to the wax microparticles are adhered to the surface.

1. Toner Particles (Toner Core), Internal Additive The toner of the present invention is a toner in which an external additive is attached to the surface of the toner particles. Furthermore, if necessary, optional components may be contained within a range that does not impair the effects of the present invention. The volume average particle diameter of the primary particles of the toner particles can be appropriately selected according to the purpose, and is, for example, 4 μm or more and 8 μm or less. In this embodiment, the toner particles contain a binder resin and internal additives such as a colorant and a release agent.

In the present invention, the toner particles are preferably thermally spherical. As described above, according to the present invention, it is possible to improve low-temperature fixability, storage stability, and light resistance, and to suppress blocking and filming even in thermally spherical toner.

<Binder resin>
As the binder resin contained in the toner particles of the present invention, a polyester-based resin can be preferably used.

The polyester resin used for the binder resin is generally selected from one or more selected from dihydric alcohol components and trihydric or higher polyhydric alcohol components, and divalent carboxylic acids and trihydric or higher polyhydric carboxylic acids. It can be obtained by polycondensation reaction of one or more of the above compounds through an esterification reaction or a transesterification reaction by a known method.

The conditions for the polycondensation reaction may be appropriately set according to the reactivity of the monomer components, and the reaction may be terminated when the polymer has suitable physical properties. For example, the reaction temperature is about 170° C. to 250° C., and the reaction pressure is about 5 mmHg to normal pressure.

Examples of dihydric alcohol components include polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (3.3)-2,2-bis(4-hydroxy phenyl) propane, polyoxypropylene (2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (2.0)-polyoxyethylene (2.0)-2,2-bis( Alkylene oxide adducts of bisphenol A such as 4-hydroxyphenyl)propane, polyoxypropylene (6)-2,2-bis(4-hydroxyphenyl)propane; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, di Diols such as propylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A; propylene adduct of bisphenol A; ethylene adduct of bisphenol A; hydrogenated bisphenol A;

Trihydric or higher polyhydric alcohol components include, for example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose (cane sugar), 1 , 2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3, 5-trihydroxymethylbenzene and the like.

In the toner of the present invention, one of the above dihydric alcohol component and trihydric or higher polyhydric alcohol component may be used alone, or two or more thereof may be used in combination.

Divalent carboxylic acids such as maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid acid, n-dodecenylsuccinic acid, n-dodecylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid, and acid anhydrides and lower alkyl esters thereof.

Examples of trivalent or higher polycarboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, and 1,2,4-naphthalene. tricarboxylic acids, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, Examples include tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, acid anhydrides, and lower alkyl esters thereof.

In the toner of the present invention, one of the divalent carboxylic acid and the trivalent or higher polyvalent carboxylic acid may be used alone, or two or more of them may be used in combination.

In the toner of the present invention, the binder resin has a weight average molecular weight in the range of 9,000 to 90,000, and the ratio of molecular weights of 100,000 or more in the molecular weight distribution is 10% to 30%. preferable. If the weight-average molecular weight and the ratio of the molecular weight of 100,000 or more of the binder resin are within the above ranges, the effect of coexisting low-temperature fixability and hot-offset resistance in a belt fixing device is further exhibited. If the weight-average molecular weight of the binder resin is less than 9,000, there is a risk that the peelability on the high-temperature fixing side may deteriorate. If the weight average molecular weight of the binder resin exceeds 90,000, the low-temperature fixability may deteriorate.

By setting the weight-average molecular weight of the binder resin to 20,000 or more, it is possible to more reliably improve the releasability on the fixing high temperature side. Further, by setting the weight average molecular weight of the binder resin to 70,000 or less, it is possible to more reliably improve the low-temperature fixability. Therefore, the more preferable range of the weight average molecular weight of the binder resin is 20,000 to 70,000.

Further, when the ratio of molecular weights of 100,000 or more in the molecular weight distribution of the binder resin is less than 10%, there is a possibility that the releasability on the fixing high temperature side may deteriorate. If the ratio of molecular weights of 100,000 or more in the molecular weight distribution of the binder resin exceeds 30%, the low-temperature fixability may deteriorate. By setting this ratio to 20% or less, the low-temperature fixability can be improved more reliably. Therefore, a more preferable range of the ratio of the molecular weight of 100,000 or more in the molecular weight distribution of the binder resin is 10% to 20%.

The content of the binder resin in the toner particles is preferably 60% by mass to 90% by mass, more preferably 70% by mass to 85% by mass.

<Colorant>
Toner particles according to the present invention may contain a colorant. As the colorant, various types and colors of organic and inorganic pigments and dyes commonly used in the field of electrophotography can be used, for example, black, white, yellow, orange, red, purple, blue, and green coloring agents.

Examples of black colorants include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite, and magnetite.

Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

Examples of yellow colorants include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138 and the like.

Examples of orange colorants include red chrome, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43 and the like.

Examples of red colorants include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, resole red, pyrazolone red, watching red, calcium salts, lake red C, lake red D, brilliant carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48:1, C.I. I. Pigment Red 53:1, C.I. I. Pigment Red 57:1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.

Examples of purple coloring agents include manganese purple, fast violet B, and methyl violet lake.

Blue colorants include, for example, Prussian Blue, Cobalt Blue, Alkali Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-Free Phthalocyanine Blue, Partially Chlorinated Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue BC, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15:2, C.I. I. Pigment Blue 15:3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60 and the like.

Examples of green coloring agents include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, C.I. I. Pigment Green 7 and the like.

In the toner of the present invention, one of the above colorants may be used alone, or two or more may be used in combination, and the combination may be of different colors or of the same color.

Moreover, two or more kinds of colorants may be formed into composite particles and used. Composite particles can be produced, for example, by adding appropriate amounts of water, lower alcohol, etc. to two or more coloring agents, granulating the mixture with a general granulator such as a high-speed mill, and drying. Furthermore, in order to uniformly disperse the colorant in the binder resin, it may be used in the form of a masterbatch. The composite particles and masterbatch are incorporated into the toner composition during dry mixing.

The content of the colorant in the toner particles according to the present invention is not particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.2 parts by mass, with respect to 100 parts by mass of the binder resin. parts by mass to 10 parts by mass.

When the content of the colorant is within the above range, an image having a high image density and very good image quality can be formed without impairing various physical properties of the toner. In terms of conversion, the content of the colorant in the toner particles is preferably 2.5% by mass to 7.5% by mass, more preferably 3.0% by mass to 6.5% by mass.

<Charge control agent>
The toner particles according to the present invention may contain charge control agents. As the charge control agent, charge control agents for positive charge control and negative charge control commonly used in the field of electrophotography can be used.

Examples of charge control agents for positive charge control include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, triphenylmethane. derivatives, guanidine salts, amidine salts and the like.

Examples of charge control agents for negative charge control include oil-soluble dyes such as oil black and spirone black, metal-containing azo compounds, azo complex dyes, metal naphthenate salts, metal complexes and metal salts of salicylic acid and its derivatives ( Metals include chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, resin acid soaps, and the like.

In the toner of the present invention, one of the above charge control agents may be used alone, or two or more thereof may be used in combination.

The content of the charge control agent in the toner of the present invention is not particularly limited, but is preferably 0.5 to 3.0 parts by weight, more preferably 0.7 parts by weight, based on 100 parts by weight of the binder resin. Parts by mass to 2.5 parts by mass. If the content of the charge control agent is within the above range, an image having a high image density and very good image quality can be formed without impairing various physical properties of the toner.

<Wax (wax as internal additive)>
Toner particles according to the present invention may contain wax. As the wax, one commonly used as a release agent in the field of electrophotography can be used. Examples thereof include petroleum waxes such as paraffin wax and derivatives thereof; hydrocarbon waxes such as polyethylene wax and derivatives thereof; carnauba wax, rice wax, candelilla wax and the like.

The toner particles according to the present invention preferably contain 0% by mass or more and 2.0% by mass or less of wax as a releasing agent. More preferably, it is 0% by mass or more and 1.5% by mass or less. If the wax content in the toner particles exceeds the above upper limit, blocking or filming may occur.

2. External Additive The toner of the present invention contains, as an external additive, wax microparticles (external wax additive) in which hydrophobic inorganic microparticles adhere to the surface. FIG. 2 schematically shows the external wax additive according to the present embodiment (right side of FIG. 2) obtained by attaching hydrophobic inorganic fine particles to the surface of wax fine particles (left side of FIG. 2).

The external additive generally has a function of improving the transportability and chargeability of the toner, and the stirrability with the carrier when the toner is used as a two-component developer. Additives) particularly have a function of improving the releasability of the toner.

The content of the wax external additive (wax fine particles having hydrophobic inorganic fine particles attached to the surface) is preferably 1.5 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the toner particles. It is more preferably 1.8 parts by mass or more and 2.7 parts by mass or less. If the content is less than the above lower limit, the releasability of the toner may be insufficient and low-temperature offset may occur. If the content exceeds the above upper limit, blocking may occur.

<Wax Fine Particles (Wax in External Wax Additive)>
The volume-based median diameter of the primary particles of the wax microparticles is 70 nm or more and 100 nm or less, more preferably 80 nm or more and 90 nm or less.

Waxes used as wax fine particles can be waxes commonly used as release agents in the field of electrophotography, as well as waxes used as internal additives. , rice wax, candelilla wax, montan wax and jojoba oil wax. Among them, polyethylene wax is particularly preferred because it is nearly neutral in charge and easy to control charging when used as an external additive.

The melting point of the fine wax particles is preferably 60° C. or higher and 130° C. or lower, more preferably 70° C. or higher and 100° C. or lower. If the melting point of the fine wax particles is less than the above lower limit, the storage stability may deteriorate. If the melting point of the fine wax particles exceeds the above upper limit, the low-temperature fixability may deteriorate.

For the wax fine particles according to the present invention, P1 is the absorbance peak height near the wave number of 1,512 cm ⁻¹ when the infrared absorption spectrum of the wax fine particles is measured by the ATR method of FT-IR, and the absorbance is displayed. When P2 is defined as the absorbance peak height near the wave number of 2,900 cm ⁻¹ , the value of P1/P2 is preferably 1.0 or less, more preferably 0.9 or less. If the value of P1/P2 exceeds the above upper limit, the light resistance may deteriorate.

The wax microparticles according to the present invention preferably have a tensile elastic modulus of 1.0×10 ³ MPa or more, more preferably 1.1×10 ³ MPa or more, as measured according to ASTM D638 standard. is more preferable. If the tensile elastic modulus of the fine wax particles is less than the above lower limit, low temperature offset may occur.

<Inorganic fine particles (inorganic fine particles on the surface of wax external additive)>
In the wax external additive according to the present invention, hydrophobic inorganic fine particles adhere to the surface of wax fine particles. Inorganic fine particles such as silica, strontium titanate, etc. whose surfaces have been subjected to hydrophobic treatment can be used as the inorganic fine particles for coating the wax fine particles in this way.

The inorganic fine particles according to the present invention are inorganic fine particles to which hydrophobicity is imparted by applying a surface treatment with a silane coupling agent, a titanium coupling agent, silicone oil, or the like. It is preferable because it reduces the decrease.

The coverage of the surfaces of the wax particles with the inorganic particles is preferably 70% or more and 100% or less, more preferably 75% or more and 95% or less. If the coverage is less than the above lower limit, filming may occur. If the coverage exceeds the above upper limit, blocking may occur.

The average primary particle size of the inorganic fine particles is preferably 12 nm or more and 40 nm or less, more preferably 15 nm or more and 35 nm or less. If the average primary particle size of the inorganic fine particles is less than the above lower limit, blocking may occur. If the average primary particle size of the inorganic fine particles exceeds the above upper limit, the storage stability may deteriorate. The average primary particle diameter of the inorganic fine particles is the average value obtained by photographing the inorganic fine particles using a scanning electron microscope (SEM) and measuring the particle diameters of 100 inorganic fine particles arbitrarily from the resulting image. .

<Other external additives>
In addition to the external wax additive, the toner of the present invention has functions such as improvement of powder fluidity, improvement of triboelectrification property, improvement of heat resistance, improvement of long-term storage stability, improvement of cleaning property, and control of photoreceptor surface abrasion property. It may contain an external additive that plays a role.

As such an external additive, inorganic fine particles such as silica, titanium oxide and alumina having an average primary particle size of 5 nm to 200 nm can be used. The surface of these inorganic fine particles is treated with a silane coupling agent, a titanium coupling agent, silicone oil, etc. to impart hydrophobicity to the inorganic fine particles. Therefore, it is preferable. The amount of the external additive to be added is preferably 0.2 parts by mass to 3 parts by mass with respect to 100 parts by mass of the toner particles. If the amount added is less than 0.2 parts by weight, it is difficult to improve the fluidity of the toner. As a method for adding the external additive, a generally used method of mixing the toner and the external additive with an airflow mixer such as a Henschel mixer can be employed.

3. Manufacturing Method of Toner A known method can be used as a manufacturing method of the toner according to the present invention. a fine pulverization step of finely pulverizing the mixture; a classification step of classifying the finely pulverized material obtained in the fine pulverization step; and a processing step.

In addition, the dry method is preferable in that the number of steps is smaller than that of the wet method, and the cost of equipment is low. Among them, the pulverization method is particularly preferable. The conditions in each of the above steps may be appropriately set according to the target material and desired physical properties.

Furthermore, as a step of manufacturing a wax external additive and externally adding it to the toner particles, a wax pulverization step of obtaining a pulverized wax slurry by using a bead mill for wax, and a wax pulverization step obtained in the wax pulverization step A coating step of adding hydrophobized inorganic fine particles to the wax slurry and stirring to obtain a wax slurry having the inorganic fine particles attached to the wax surface, and drying the wax slurry obtained in the coating step. Thus, a drying step of obtaining wax fine particles having hydrophobic inorganic fine particles attached to their surfaces, and the wax fine particles obtained in the drying step and toner particles are mixed to attach the wax fine particles to the surfaces of the toner particles. and an external addition step of obtaining a toner.

<Mixing process>
In the mixing step, a toner material containing known additives such as a binder resin, a colorant, and optionally a charge control agent is mixed, melted and kneaded, further mixed with a filler, and the resulting kneaded product is A mixture is obtained by solidifying by cooling and coarsely pulverizing.

Mixing is preferably dry, and as a mixer, a known device commonly used in the art can be used. Henschel type mixing equipment such as Mechanomill (trade name, manufactured by Okada Seiko Co., Ltd.), Ong Mill (trade name, manufactured by Hosokawa Micron Corporation), Hybridization System (trade name, Nara Machinery Co., Ltd.) Seisakusho) and Cosmo System (trade name, manufactured by Kawasaki Heavy Industries, Ltd.).

As a kneader, a known device commonly used in the technical field can be used, and examples thereof include general kneaders such as a twin-screw extruder, a triple roll, and a laboblast mill. Specifically, for example, TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65/87, PCM-30 (all of these are trade names, manufactured by Ikegai Co., Ltd.), etc. uniaxial or biaxial extruders , Kneedex (trade name, manufactured by Mitsui Mining Co., Ltd.) and other open-roll type kneaders. It is preferable in that it can be dispersed.

<Fine pulverization process>
In the finely pulverizing step, the mixture obtained in the mixing step is finely pulverized. As the pulverizer, known devices that are commonly used in the art can be used. ) is introduced into the space formed between the solidified material and crushed.

<Classification process>
In the classifying step, the finely pulverized material obtained in the finely pulverizing step is classified. Classification is preferably performed by a known device commonly used in the art, particularly a classifier capable of removing excessively pulverized toner particles by centrifugal force and wind power, such as a swirling air classifier (rotary air classifier). can.

<Thermal spheroidization process>
In the thermal spheronization treatment step, the classified material obtained in the classification step is spheroidized by hot air to obtain toner particles. As the hot air device, a known device that is commonly used in the relevant technical field can be used.

<Wax pulverization process>
In the wax pulverization step, a bead mill is used to obtain a pulverized wax slurry. As the pulverization device, a known device commonly used in the technical field can be used. The bead mill treatment in the production method of the present invention may be either dry or wet, but wet bead mill treatment is preferably employed. As the solvent in this case, in addition to water, alcoholic solvents such as methanol, ethanol, isopropanol and butanol can be used. Examples of wet bead mill equipment include wet bead mill LABOSTAR manufactured by Ashizawa Fine Tech Co., Ltd.

<Coating process>
In the step of coating the surfaces of the wax microparticles with inorganic microparticles, hydrophobic inorganic microparticles are added to the wax slurry obtained in the wax micropulverization step and stirred to form a suspension, thereby coating the wax surfaces with the inorganic microparticles. A wax slurry to which inorganic fine particles are attached is obtained. As the suspending apparatus, a well-known apparatus commonly used in the technical field can be used, for example, an aluminum air motor vertical stirrer (Bernoulli flow stirrer BEAG E type) manufactured by Nitto Metal Industry Co., Ltd. can be used.

<Drying process>
In the drying step, the wax slurry obtained in the coating step is dried to obtain wax microparticles (wax external additive) having hydrophobic inorganic microparticles adhered to their surfaces. As a drying device, for example, a flash jet dryer manufactured by Seishin Enterprise Co., Ltd. can be used.

<External Addition Process>
In the external addition step, the toner particles obtained in the spheroidization treatment step, the wax external additive obtained in the drying step, and optionally the “other external additives” (hydrophobic silica particles, etc.) are mixed. , the toner is obtained by adhering the external additive to the surface of the toner particles.

As the mixer in the external addition step, a known device commonly used in the art can be used, and examples thereof include the mixers exemplified in the above “mixing step”.

4. Developer The toner of the present invention can be used as it is as a one-component developer, or can be mixed with a carrier and used as a two-component developer. When used as a one-component developer, the toner is used without a carrier. When used as a one-component developer, a blade and a fur brush are used to triboelectrically charge the toner so that the toner adheres to the developing sleeve, thereby conveying the toner and forming an image.

When the toner of the present invention is used as a two-component developer, the two-component developer can be prepared by mixing the toner and the carrier. As a mixing device used for mixing, for example, a powder mixer such as a V-type mixer (trade name: V-5, manufactured by Tokuju Kosakusho Co., Ltd.) can be used. The blending ratio of toner and carrier is, for example, a weight ratio of 10:90 to 5:95. The carrier is not particularly limited, and a carrier commonly used in two-component developers can be used. For example, a coated carrier can also be used.

EXAMPLES The present invention will be described below based on Examples and Comparative Examples, but the present invention is not limited to these Examples. First, the methods of measurement and evaluation performed in Examples and Comparative Examples will be described.

[Evaluation 1. Evaluation Method for Storage Stability of Toner]
10 g of toner was placed in a 100 ml glass bottle and left in a constant temperature bath at a temperature of 50° C. for 24 hours. The toner was sieved through an ultrasonic sieve of 400 mesh (trade name: digitally controlled DGS oscillator, manufactured by Artec Ultrasonic Co., Ltd.) for 1 minute, and then the presence or absence of aggregated toner was checked.

Evaluation criteria for storage stability are as follows.
◯ (Good): No aggregated toner visually observed.
Δ (fairly good): There is aggregated toner that is crushed by ultrasonic sieve.
x (defective): there is agglomerated toner that cannot be crushed by the ultrasonic sieve.

[Evaluation 2. Low-temperature fixability evaluation method]
Toner and coat carrier (genuine carrier for MX-5111FN manufactured by Sharp Corporation) are mixed with a V-type mixer (trade name: V-5, manufactured by Tokuju Kosakusho Co., Ltd.) so that the toner concentration is 7% by mass. A two-component developer was prepared by mixing for 20 minutes.

A commercially available copier (trade name: MX-5111FN, manufactured by Sharp Corporation) having a developing device was filled with the above two-component developer, and an A4 test document having a rectangular solid image of 20 mm long and 50 mm wide was copied. , the presence or absence of low-temperature offset was examined on a recording medium (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation). At this time, the amount of toner adhering to the solid image portion was set to 0.5 mg/cm ² , and the temperature of the fixing roller was set to 135°C. Note that low-temperature offset means that the toner is not fixed on the recording paper at the time of fixing, and the toner re-adheres to the recording paper after the fixing roller completes one turn while remaining adhered to the fixing roller.

Evaluation criteria for low-temperature fixability are as follows.
◯ (Good): No redeposition of toner to the recording paper was observed.
Δ (fairly good): Some redeposition of toner to the recording paper is observed, but the reflection density (ID) of the redeposited image is less than 0.1.
x (defective): reattachment of toner to the recording paper is clearly observed, and the reflection density (ID) of the reattached image is 0.1 or more.

[Evaluation 3. Blocking evaluation method]
A commercially available copier (trade name: MX-5111FN, manufactured by Sharp Corporation) was filled with the above two-component developer, and 100,000 sheets of character originals with a coverage of 6% were prepared under an environment of room temperature of 20°C and humidity of 65%. After 10 sheets of paper were continuously copied intermittently, the presence or absence of toner aggregates and the state of the developer conveyed by the developing roller were visually checked.

Evaluation criteria for blocking are as follows.
◯ (Good): No toner aggregates were observed, and the developer was uniformly conveyed by the developing roller.
Δ (practically no problem): Toner aggregates are observed, but the developer is uniformly transported on the developing roller.
x (defective): Toner aggregates were observed, and the developer was not uniformly transported on the developing roller.

[Evaluation 4. Evaluation method of filming on photoreceptor]
A commercially available copier (trade name: MX-5111FN, manufactured by Sharp Corporation) is filled with the above two-component developer, and a predetermined print pattern with a printing rate of 1% is printed under an HH environment (temperature: 28°C, humidity: 80%). Printed continuously. After continuous printing of 5,000 sheets, the photoreceptor and the solid image were visually observed and evaluated.

Evaluation criteria for filming are as follows.
◯ (Good): No filming occurred on the photoreceptor, and the image was satisfactory.
Δ (no problem in practical use): Some filming occurred on the photoreceptor, but there was no problem with the image.
x (defective): A lot of filming occurred on the photoreceptor, and there was also a problem with the image.

[Evaluation 5. Method for Evaluating Light Resistance of Toner]
Evaluation 2 above. (Evaluation of Low-Temperature Fixability) Using a xenon tester (AtlasCi4000, manufactured by Suga Test Instruments Co., Ltd.), illuminance: 0.39 W/m ² at a wavelength of 340 nm, temperature: An exposure test was performed for 100 hours under conditions of 40° C. and relative humidity of 70%. The chromaticity of the image sample was measured before and after the test, and ΔE defined by the following formula was measured. The initial chromaticities are _a0 ^* , _b0 ^* , _L0 ^* , and the chromaticities after exposure are a ^* , b ^* , L ^* .

The light resistance evaluation criteria are as follows.
○ (extremely excellent light resistance): ΔE < 10
△ (excellent light resistance): 10 ≤ ΔE < 20
× (poor light resistance): 20 ≤ ΔE

[Comprehensive evaluation method]
The results of the above evaluations 1 to 5 were scored with "○" as +1, "Δ" as ±0, and "×" as -1.
⊚ (excellent): The total score is 5 (usable).
○ (Good): The total score is 4 (usable).
△ (Possible): The total score is 2 to 3 (can be used).
x (impossible): there is one or more x (cannot be used).

Next, procedures for manufacturing toners in Examples and Comparative Examples will be described.

[Example 1]
<Production of Toner Particles>
- Binder resin: polyester resin (peak top molecular weight Mp 5,300, melting temperature Tm 99°C, glass transition temperature Tg 60°C, manufactured by Mitsubishi Chemical Corporation, product name: Diaclone ER-535) 89.0% by mass
Coloring agent: carbon black (manufactured by Cabot Corporation, product name: Regal 1330) 8.0% by mass
・Charge control agent: salicylic acid compound (Orient Chemical Industry Co., Ltd., product name: Bontron E-84) 2.0% by mass
・ Release agent: Wax (Mitsui Chemicals, Inc., product name: Hi-Wax NP105) 1.0% by mass
Using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd. (currently Nippon Coke Industry Co., Ltd.), model: FM20C), the above materials were premixed for 5 minutes, and then a twin-screw extruder (manufactured by Ikegai Co., Ltd., model: PCM30) ), and melt-kneaded under the conditions of a cylinder set temperature of 110° C., a barrel rotation speed of 200 rpm, and a raw material feed rate of 15 kg/h to obtain a melt-kneaded product [mixing/kneading step].

The resulting melt-kneaded product was cooled with a drum flaker and then coarsely pulverized using a cutting mill (manufactured by Orient Co., Ltd., model: VM-16) to obtain a coarsely pulverized product [coarse pulverization step].

Next, the obtained coarsely pulverized product was finely pulverized using a jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd., model: IDS-2) to obtain a finely pulverized product [fine pulverization step].

The resulting finely pulverized product was classified using an elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd., model: EJ-LABO) to obtain toner particles having an average primary particle diameter of 5.5 μm [classification step]. .

To 100 parts by mass of the obtained toner particles, 3.0 parts by mass of silica fine particles (manufactured by Nippon Aerosil Co., Ltd., trade name: RX50) are added, and Henschel Mixer (manufactured by Mitsui Mining Co., Ltd. (currently Nippon Coke Kogyo Co., Ltd.), Model: FM-75), rotation speed 30s ^-1 , rotation time 10min. and heat treated by Meteor Rainbow. The operating conditions were feed amount: 4 kg/hr, hot air temperature C: 210°C, hot air flow rate: 6 m ³ /min. , cold air temperature E: 5°C, cold air flow rate: 4 m ³ /min. , cold air absolute water content: 3 g/m ³ , blower air volume: 20 m ³ /min. , injection air flow rate: 1 m ³ /min. and The resulting thermally spherical toner particles had an average circularity of 0.963 and a weight average particle diameter (D4) of 5.9 μm [thermally sphericalizing treatment step].

<Preparation of wax external additive>
(Preparation of wax slurry)
A wax slurry (wax dispersion) was prepared by dispersing Polywax 500 (manufactured by Toyochem Co., Ltd., melting point 90° C.) in a solvent as follows.

450 g of this wax powder was added to 1,050 g of ion-exchanged water to prepare a mixed liquid. A dispersion liquid (wax slurry) containing fine wax particles was obtained [wax pulverization step].

(Particle size measurement of wax)
The volume-based median diameter (D50) of the fine wax particles in the obtained wax slurry was measured with Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.) and found to be 90 nm.

(Coating with inorganic fine particles)
1,500 mL of the obtained wax slurry and 600 g of H2000/4 (manufactured by Clariant Chemicals Co., Ltd., primary particle diameter 18 nm) as inorganic fine particles are put into a tank and stirred at 900 rpm for 30 minutes with an aluminum air motor stirrer. Thus, an inorganic fine particle-coated wax slurry was obtained in which the inorganic fine particles covered the surfaces of the wax fine particles at a rate of 85% [coating step].

(Drying process)
The resulting inorganic fine particle-coated wax slurry was dried with a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.) to obtain a wax external additive (1). The drying conditions were as follows: blowing temperature of 60° C., outlet temperature of the dryer of 30° C., and wax slurry supply rate adjusted so that the outlet temperature does not deviate from 30° C. [drying step].

<External Addition Process>
100 parts by mass of the unexternally added toner particles obtained in the thermal spheroidization step, 1.0 parts by mass of hydrophobic silica fine particles (average primary particle diameter 7 nm, manufactured by Nippon Aerosil Co., Ltd., trade name: Femed Silica R976S), and 2.5 parts by mass of the external wax additive (1) are put into a Henschel mixer, and the peripheral speed at the outermost periphery of the tip of the stirring blade is set to 40 m/s, and the toner (1) (volume An average particle diameter of 5.9 μm and a coefficient of variation of 24%) was obtained (external addition step).

[Examples 2 to 22, Comparative Examples 1 to 7]
The types of wax in the external wax additives used in the toners of Examples and Comparative Examples are shown in Table 1 below, and the types of inorganic fine particles in the external wax additives are shown in Table 2 below. Toners of Examples 2 to 22 and Comparative Examples 1 to 7 were prepared in the same manner as in Example 1, except that external wax additives in which these were combined as shown in Table 3 below were used as shown in Table 4 below. got

Regarding the wax type in the wax external additive used in Examples and Comparative Examples, in detail, polyethylene wax was used in Examples 1, 6, 7, 19, 20 and Comparative Example 2, and rice wax was used in Examples 2, 15, and 17. wax, candelilla wax in Examples 3 and 11, ester wax in Examples 4 and 5 and Comparative Examples 1, 4, 5 and 7, and montan wax in Examples 8, 10 and 18; Paraffin in Examples 9 and 14, carnauba wax in Examples 12 and 16, jojoba oil wax in Example 13, and 1,3-(hydroxymethyl)urea in Example 21. No. 22 and Comparative Example 3 are diphenyl urethane.

Regarding the inorganic fine particle species in the wax external additives used in Examples and Comparative Examples, in detail, Examples 5, 8, 14, 16, 18 and Comparative Example 6 used strontium titanate whose surface was hydrophobized. In the other examples and comparative examples, the silica was surface-hydrophobized.

As is clear from the evaluation results shown in Table 5, the toner has an external additive attached to the surface of the toner particles, and the external additive contains wax fine particles having hydrophobic inorganic fine particles attached to the surface. Examples 1 to 22, in which the volume-based median diameter of the primary particles of the wax fine particles was 70 nm or more and 100 nm or less, were excellent in the evaluation of low-temperature fixability, storage stability, light resistance, blocking and filming.

In contrast, Comparative Examples 1 to 7, which did not satisfy these requirements, were inferior to Examples in at least one evaluation of low-temperature fixability, high-temperature fixability, and heat-resistant storage stability.

It can be seen that Example 1, etc., in which the surface coverage of the wax fine particles with the inorganic fine particles is 70% or more and 100% or less, is particularly excellent in evaluation of filming, compared to Example 8, in which the coverage is less than the above lower limit. In addition, it can be seen that the evaluation of blocking is particularly superior to Example 9 in which the coverage exceeds the above upper limit.

It can be seen that Example 1, etc., in which the wax fine particles have a melting point of 60° C. or more and 130° C. or less, are particularly superior in evaluation of storage stability than Example 4, in which the melting point is less than the above lower limit. In addition, it can be seen that the evaluation of the low-temperature fixability is superior to that of Example 7, in which the melting point exceeds the above upper limit.

Example 1, etc., in which the average primary particle size of the inorganic fine particles is 12 nm or more and 40 nm or less, is found to be particularly excellent in the evaluation of blocking than Example 10, in which the average primary particle size is less than the above lower limit. Moreover, it can be seen that the evaluation of storage stability is particularly superior to Example 13, in which the average primary particle size exceeds the above upper limit.

In Example 1, etc., the content of wax fine particles (wax external additive) having inorganic fine particles adhered to the surface is 1.5 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of toner particles. It can be seen that the evaluation of the low-temperature fixability is particularly superior to that of Example 14 in which the amount is less than the above lower limit. In addition, it can be seen that the evaluation of blocking is particularly superior to Example 17 in which the content exceeds the above upper limit.

It can be seen that Example 1, etc., in which the value of P1/P2 is 1.0 or less, is particularly excellent in the evaluation of light resistance as compared with Example 21, in which the value of P1/P2 exceeds the above upper limit.

Example 1, etc., in which the wax microparticles have a tensile modulus of elasticity of 1.0×10 ³ MPa or more as measured based on the ASTM D638 standard, are particularly low-temperature fixable than Example 22, in which the tensile modulus of elasticity is less than the above lower limit. It can be seen that the evaluation of sex is excellent.

Example 1, etc., in which the toner particles contain 0% by mass or more and 2.0% by mass or less of wax as a releasing agent, are more suitable for evaluation of blocking and filming than Example 20, in which the wax content exceeds the above upper limit. I know you're good.

[Other embodiments]
In addition, the embodiment disclosed this time is an example in all respects, and does not serve as a basis for a restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted only by the above-described embodiments, but is defined based on the claims. In addition, the technical scope of the present invention includes all modifications within the meaning and range of equivalence to the claims.

I Hydrophobized inorganic fine particles P Pulverized toner particles P′ Thermally spherical toner particles W1 Wax (internal additive)
W1' Bleed-out wax W2 Wax microparticles (external additive)

Claims (12)

A toner in which an external additive is attached to the surface of the toner particles,
The external additive contains wax fine particles having hydrophobic inorganic fine particles attached to the surface,
A toner, wherein a volume-based median diameter of primary particles of the wax fine particles is 70 nm or more and 100 nm or less. The toner according to claim 1,
A toner, wherein said toner particles are thermally spherical toner particles. 3. The toner according to claim 1 or 2,
A toner, wherein a coverage of the surface of the wax fine particles with the inorganic fine particles is 70% or more and 100% or less. The toner according to any one of claims 1 to 3,
A toner, wherein the wax fine particles have a melting point of 60° C. or higher and 130° C. or lower. The toner according to any one of claims 1 to 4,
A toner, wherein the inorganic fine particles have an average primary particle size of 12 nm or more and 40 nm or less. The toner according to any one of claims 1 to 5,
A toner, wherein the inorganic fine particles are silica or strontium titanate having a hydrophobic surface. The toner according to any one of claims 1 to 6,
A toner according to claim 1, wherein a content of wax fine particles having inorganic fine particles adhered to the surface thereof is 1.5 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the toner particles. The toner according to any one of claims 1 to 7,
A toner, wherein the wax fine particles contain at least one selected from the group consisting of ester wax, paraffin wax, polyethylene wax, carnauba wax, rice wax, candelilla wax, montan wax and jojoba oil wax. The toner according to any one of claims 1 to 8,
When the infrared absorption spectrum of the wax fine particles is measured by the ATR method of FT-IR and the absorbance is displayed, the absorbance peak height near the wave number of 1,512 cm ^-1 is P1, and the absorbance peak near the wave number of 2,900 cm ^-1 . A toner characterized in that the value of P1/P2 is 1.0 or less when the height is defined as P2. The toner according to any one of claims 1 to 9,
A toner, wherein the wax fine particles have a tensile elastic modulus of 1.0×10 ³ MPa or more, as measured according to ASTM D638 standard. The toner according to any one of claims 1 to 10,
A toner, wherein the toner particles contain 0% by mass or more and 2.0% by mass or less of wax as a releasing agent. A method for producing the toner according to any one of claims 1 to 11, comprising:
a wax pulverization step of using a bead mill on the wax to obtain a pulverized wax slurry;
a coating step of adding hydrophobic inorganic fine particles to the wax slurry obtained in the wax pulverization step and stirring the wax slurry to obtain a wax slurry in which the inorganic fine particles are attached to the surface of the wax;
a drying step of drying the wax slurry obtained in the coating step to obtain wax fine particles having hydrophobic inorganic fine particles attached to the surface;
an external addition step of mixing the wax fine particles obtained in the drying step with toner particles to obtain a toner having the wax fine particles adhered to the toner particle surfaces;
A method for producing a toner, wherein a wet bead mill is used in the wax pulverization step.

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