JP2022070772A - Toner and image forming method - Google Patents

Abstract

To solve the problem in which: a reduction in particle diameter of toner causes scattering of fine powder from carrier on a developing roller and deterioration of contamination in a fuser and fogging on a white background of an image.SOLUTION: A toner has toner particles containing a binder resin and silica fine particles on the surface of each of the toner particles. The silica fine particles contain silica fine particles A containing iron atoms. Primary particles of the silica fine particles A have a number average particle diameter of 80 nm or more and 200 nm or less. After 1800 seconds from when the silica fine particles A are electrified in an environment of a temperature of 23°C and a relative humidity of 50%, the silica fine particles A have a charge attenuation constant α of 0.0005 or more and 0.0100 or less. The toner particles have a weight average particle diameter (D4) of 3.0 μm or more and 5.7 μm or less.SELECTED DRAWING: None

Description

The present invention relates to toner used in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and a toner jet method. The present invention also relates to an electrophotographic image forming method.

As copiers and printers become more widespread, the performance required of toner is becoming more sophisticated. In recent years, a digital printing technique called print on demand (POD), which directly prints without going through a plate making process, has attracted attention. This print-on-demand (POD) is advantageous over conventional offset printing because it can support small lot printing, printing in which the content is changed for each sheet (variable printing), and distributed printing. Considering the application of the image formation method using toner to the POD market, stable high-quality print products can be produced even when a large amount of images are output at high speed for a long period of time in various environments. It is required to obtain. One of the items that deteriorates the quality of print products is white background image fog. The following patent documents have proposed a method for suppressing image fog on a white background, which is a phenomenon in which toner adheres to a portion that is originally desired to be a white background and the image quality is deteriorated.

Patent Document 1 uses alumina particles having a particle size of 5 to 60 nm as a toner externalizing agent, thereby reducing the amount of the external additive transferred to the carrier and maintaining the chargeability, and the white background portion of the image. It suppresses fog.
Further, in Patent Document 2, as a toner external additive, the primary particle size is 30 nm or more and 100 nm or less, the average circularity of the primary particles is 0.82 or more and 0.94 or less, and the circularity such that the cumulative number of primary particles is 84% is 0.92. By using super strontium titanate, it has excellent dispersibility, maintains chargeability, and suppresses fog on the white background of the image.

Japanese Unexamined Patent Publication No. 2019-138990 Japanese Unexamined Patent Publication No. 2019-28428

However, although the configurations of Patent Documents 1 and 2 have a certain effect on suppressing fog on the white background of the image, the amount of fine powder smaller than the average particle size of the toner and the toner is large due to the smaller particle size of the toner. In that case, the electrostatic binding force with the carrier is reduced, and there is a possibility that the contamination inside the developer and the fog on the white background of the image are deteriorated.

The above problems can be solved by using the following toners.
Toner particles containing a binder resin and toner having silica fine particles on the surface of the toner particles. The silica fine particles contain silica fine particles A containing an iron atom, and the silica fine particles A are primary particles. The charge decay constant α after 1800 seconds from the charged state in an environment where the number average particle size is 80 nm or more and 200 nm or less and the temperature is 23 ° C. and the relative humidity is 50% is 0.0005 or more and 0.0100 or less.
The toner is characterized in that the weight average particle size (D4) of the toner particles is 3.0 μm or more and 5.7 μm or less.

According to the present invention, the toner fluidity is maintained, toner aggregation is prevented, the electrostatic binding force between the fine powder and the carrier on the developing roller is improved, the scattering of fine powder is reduced, and the white background of the image is fogged. Can be suppressed.

Hereinafter, embodiments for carrying out the present invention will be described in detail.
One embodiment of the present invention is a toner having toner particles containing a binder resin and silica fine particles on the surface of the toner particles.
The silica fine particles contain silica fine particles A containing an iron atom.
The silica fine particles A have a charge attenuation constant α of 0.0005 after 1800 seconds from being charged in an environment where the number average particle size of the primary particles is 80 nm or more and 200 nm or less and the temperature is 23 ° C. and the relative humidity is 50%. More than 0.0100 or less,
The present invention relates to a toner characterized in that the weight average particle size (D4) of the toner particles is 3.0 μm or more and 5.7 μm or less.

Further, another embodiment of the present invention is that the weight average particle size (D4) of the toner is 3.0 μm or more and 5.3 μm or less, and that the silica fine particles A contain 20 ppm or more and 2000 ppm or less of iron atoms. The silica fine particles A relate to a toner characterized by containing 200 ppm or more and 2000 ppm or less of aluminum atoms, and the silica fine particles A are hydrophobicized silica particles.

By using such a toner of the present invention, it is possible to suppress the fog of the white background portion of the image, which is the problem.

The present inventors presume the mechanism of action and effect of suppressing the fog on the white background of this image by using the toner of the present invention as follows.

The reason why the inside of the developing device is contaminated and the white background of the image is fogged is that the electrostatic binding force of the toner and the fine powder with the carrier tends to decrease.

In the present invention, it is considered that the following actions and effects are exhibited by externally adding silica that causes appropriate charge attenuation to the toner particles. Toner externally supplemented with silica that causes moderate charge attenuation has a rapid charge rise and rapid charge exchange, so that the electrostatic binding force on the carrier increases, the toner and fine powder scatter, and the photoconductor By eliminating the adhesion to the image, contamination inside the developer and fog on the white background of the image are suppressed. In particular, when a toner having a small particle size is used in a high temperature and high humidity environment, the particle size of the fine powder is often small, the amount of the fine powder tends to increase, and there is a concern that the charge may decrease. The effect when the above toner is used is more remarkable. As described above, by externally adding silica, which has a relatively large particle size and causes appropriate charge attenuation, to the toner particles, toner fluidity is ensured, toner aggregation, contamination inside the developer, and fog on the white background of the image. Can be prevented.
Each component for achieving the object in the present invention will be described in detail below.

[Silica fine particles A]
As the toner of the present invention, silica fine particles A having silicon oxide (silica) fine particles on the surface of the toner particles and having an average number of primary particles of 80 nm or more and 200 nm or less can be preferably used. Since the particle size of the silica fine particles A is within the above range, the convex portion can be maintained on the toner surface even when a mechanical load is applied in the developing device, the toner charge amount does not easily decrease, and the reflection density does not vary. Contributes to the reduction of fog in the image area.

The silica fine particles A used in the present invention are particles containing silica (that is, SiO ₂ ) as a main component, and can be produced by a known production method such as a combustion method, a melting method, or hydrothermal synthesis. Among them, silica fine particles A produced by the combustion method or the melting method are more suitable in order to further enhance the effect of suppressing charge relaxation in a high temperature and high humidity environment and from the viewpoint of high resistance and being less susceptible to humidity. preferable.

In the combustion method, siloxane gas is introduced into a burner together with a carrier gas such as nitrogen by vaporizing a siloxane compound, and silica fine particles are produced by diffusing and mixing with a combustion-supporting gas such as oxygen to burn the siloxane gas. The method. Another combustion method is a method in which silicon tetrachloride is burned at a high temperature together with a mixed gas of oxygen, hydrogen, for example, a diluting gas such as nitrogen to generate silica fine particles (fumed silica).
Further, the melting method is a method in which a metal silicon fine particle slurry is sprayed into a flame and sphericalized while undergoing an oxidation reaction to obtain silica particles.

In the present invention, a combustion method in which siloxane gas is burned to generate silica fine particles is preferable from the viewpoint of controlling the number average particle size of the primary particles of silica fine particles A to 80 nm or more and 200 nm or less and containing iron atoms. Take as an example.
Examples of the siloxane compound include hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane. As a method of containing the metal atom in the silica fine particles A, the purity of the siloxane compound can be adjusted and contained.

In the present invention, the silica fine particles A used in the present invention can be obtained by containing an iron atom, preferably an aluminum atom, in the silica fine particles A.
There is a method of incorporating these metal atoms into the silica fine particles A while adjusting the purity of the siloxane compound.
From the viewpoint of ensuring toner fluidity and preventing toner aggregation, contamination in the developer, and fog on the white background of the image, the silica fine particles A contain 20 ppm or more and 2000 ppm or less of iron atoms and 200 ppm of aluminum atoms. It is preferably contained in an amount of 2000 ppm or more and 2000 ppm or less.
Further, from the viewpoint of ensuring toner fluidity and preventing toner aggregation, contamination in the developing device, and fog on the white background of the image, the silica fine particles A are charged in an environment of a temperature of 23 ° C. and a relative humidity of 50%. It is preferable that the charge decay constant α 1800 seconds after the state is 0.0005 or more and 0.0100 or less.

The surface of the silica fine particles may be surface-treated with a fatty acid or a metal salt thereof, a disilylamine compound, a halogenated silane compound, a silicone oil, a silane coupling agent, a titanium coupling agent, or the like. The hydrophobizing treatment by these is preferable in that the charging stability of the toner can be improved particularly in a high temperature and high humidity environment. Among them, n-octylethoxysilane treatment, 3,3,3-trifluoropropyltrimethoxysilane treatment, and hexamethyldisilazane treatment are preferable in that the effect of charge stability is further enhanced.

For mixing the silica fine particles with the toner particles, known mixers such as Henshell mixer, Mechanohybrid (manufactured by Nippon Coke Co., Ltd.), Supermixer, Nobilta (manufactured by Hosokawa Micron Co., Ltd.) can be used, and the apparatus is particularly limited. is not. The amount of the silica fine particles added in the present invention is 0.5% by mass or more and 15% by mass or less with respect to the toner particles.

[Other external additives]
In addition to the silica fine particles described above, the toner of the present invention may contain other inorganic fine powders, if necessary, in order to adjust the charge amount and fluidity. The inorganic fine powder may be internally added to the toner particles or may be mixed with the toner particles as an external additive. As the external additive, inorganic fine powders such as silica, titanium oxide, strontium titanate, aluminum oxide, magnesium oxide, and calcium carbonate are preferable. The inorganic fine powder may be hydrophobized with a hydrophobizing agent such as a stearic acid compound, a silane compound, a silicone oil or a mixture thereof.

The external additive is preferably used in an amount of 0.1 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the toner particles. A known mixer such as a Henschel mixer can be used for mixing the toner particles and the external additive.

[Bundling resin]
The binder resin used for the toner of the present invention is not particularly limited, and the following polymers or resins can be used.

For example, homopolymers of styrene such as polystyrene, poly-p-chlorstyrene, polyvinyltoluene and its substitution products; styrene-p-chlorstyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalin copolymer. , Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chlormethylmethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl ether copolymer, styrene-vinyl Stylized copolymers such as ethyl ether copolymers, styrene-vinylmethylketone copolymers, styrene-acrylonitrile-inden copolymers; polyvinyl chlorides, phenolic resins, natural modified phenolic resins, natural resin modified maleic acid resins, Acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, kumaron-inden resin, petroleum resin and the like can be used.

Among these, it is preferable to use a polyester resin from the viewpoint of low temperature fixability and chargeability control.

The polyester resin preferably used in the present invention is a resin having a "polyester unit" in the binder resin chain. Specifically, the component constituting the polyester unit is a divalent or higher valent alcohol monomer. Examples thereof include a component and an acid monomer component such as a divalent or higher carboxylic acid, a divalent or higher carboxylic acid anhydride, and a divalent or higher carboxylic acid ester.

For example, examples of the divalent or higher valent alcohol monomer component include the following. Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2. 0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) alkylene oxide adduct of bisphenol A such as -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, dipropylene glycol, polyethylene glycol, polypropylene glycol, poly Tetramethylene glycol, sorbit, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5- Pentantriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like.

Among these, the alcohol monomer component preferably used is an aromatic diol, and the alcohol monomer component constituting the polyester resin preferably contains the aromatic diol in a proportion of 80 mol% or more.

On the other hand, examples of the acid monomer component such as the divalent or higher carboxylic acid, the divalent or higher carboxylic acid anhydride and the divalent or higher carboxylic acid ester include the following. Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; alkyl groups or alkenyl having 6 to 18 carbon atoms. Group-substituted succinic acid or its anhydride; unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid or their anhydrides.

Among these, the acid monomer component preferably used is a polyvalent carboxylic acid such as terephthalic acid, succinic acid, adipic acid, fumaric acid, trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid and its anhydride.

The acid value of the polyester resin is preferably 20 mgKOH / g or less from the viewpoint of the dispersibility of the pigment and the stability of the triboelectric charge amount.

The acid value can be set in the above range by adjusting the type and blending amount of the monomer used in the resin. Specifically, it can be controlled by adjusting the alcohol monomer component ratio / acid monomer component ratio and the molecular weight at the time of resin production. Further, it can be controlled by reacting the terminal alcohol with a polyhydric acid monomer (for example, trimellitic acid) after the ester condensation polymerization.

[Colorant]
When developing with the toner of the present invention to form a full-color image, a color toner of black toner, magenta toner, cyan toner, and yellow toner is prepared and used by containing a colorant. Examples of the colorant that can be contained in the toner of the present invention include the following.

As the black colorant, carbon black is mainly used, and dyes and pigments may be added as needed. In addition, a yellow colorant and a magenta colorant and a cyan colorant are used to adjust the color to black. Although the pigment may be used alone as the colorant, it is more preferable to improve the sharpness by using the dye and the pigment in combination from the viewpoint of the image quality of the full-color image.

Examples of the magenta coloring pigment include the following. C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 5.7: 1, 58, 60, 63, 64, 68, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269, 282; C. I. Pigment Violet 19; C.I. I. Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

Examples of the magenta coloring dye include the following. C. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; C.I. I. Disperse thread 9; C.I. I. Solvent Violet 8, 13, 14, 21, 27; C.I. I. Oil-soluble dyes such as Disper Violet 1, C.I. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; C.I. I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

Examples of the cyan coloring pigment include the following. C. I. Pigment Blue 2, 3, 15: 2, 15: 3, 15: 4, 16, 17; C.I. I. Bat Blue 6; C.I. I. Acid blue 45, a copper phthalocyanine pigment in which one or more and five or less phthalocyanine methyl groups are substituted in the phthalocyanine skeleton.
Examples of the cyan coloring dye include C.I. I. There is Solvent Blue 70.

Examples of the yellow coloring pigment include the following. C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65.73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; C.I. I. Bat Yellow 1, 3, 20.
Examples of the yellow coloring dye include C.I. I. There is Solvent Yellow 162.

The colorant is preferably used in an amount of 0.1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.

[Release agent: wax]
Examples of the mold release agent used in the toner of the present invention include the following waxes.
Hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymers, microcrystallin wax, paraffin wax, Fishertropch wax; oxides of hydrocarbon waxes such as polyethylene oxide wax or block copolymers thereof; Waxes containing fatty acid esters such as carnauba wax as the main component; deoxidized fatty acid esters such as carnauba wax partially or wholly deoxidized.

In addition, the following can be mentioned. Saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brushzic acid, eleostearic acid, and parinalic acid; Saturated alcohols such as sill alcohol; Polyhydric alcohols such as sorbitol; Fatty acids such as palmitic acid, stearic acid, behenic acid and montanic acid, and stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubil alcohol, ceryl alcohol and meli Esters with alcohols such as silalic acid; fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, hexamethylene bissteare Saturated fatty acid bisamides such as acid amides; unsaturated fatty acid amides such as ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N'-diorail adipic acid amide, N, N'-diorail sebasic acid amide. Aromatic bisamides such as m-xylene bisstearic acid amide, N, N'-distearylisophthalic acid amide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally) Metal soap); Waxes obtained by grafting aliphatic hydrocarbon wax with vinyl monomer such as styrene and acrylic acid; fatty acid such as behenic acid monoglyceride and partial esterified product of polyhydric alcohol; A methyl ester compound having a hydroxyl group obtained by hydrogenation of vegetable fats and oils.

Among these waxes, hydrocarbon waxes such as paraffin wax and Fisher Tropsch wax, or fatty acid ester waxes such as carnauba wax are preferable from the viewpoint of improving low temperature fixing property and high temperature offset resistance.

The content of the wax is preferably 1.0 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the binder resin. When the content of the wax is in this range, the offset resistance at high temperature can be efficiently exhibited.

Further, from the viewpoint of achieving both toner storage stability and high temperature offset resistance, the maximum endothermic curve at the time of temperature rise measured by a differential scanning calorimeter (DSC) is in the range of temperature 30 ° C. or higher and 200 ° C. or lower. The peak temperature of the endothermic peak is preferably 50 ° C. or higher and 110 ° C. or lower.

[Wax dispersant]
In order to improve the dispersibility of the wax in the binding resin, a resin having both a polar portion close to the wax component and a portion close to the resin polarity may be added as the wax dispersant. Specifically, a styrene acrylic resin graft-modified with a hydrocarbon compound is preferable.

When a cyclic hydrocarbon group or an aromatic ring is introduced into the resin portion of the wax dispersant, the charge retention of the toner is improved. This is preferable because it suppresses the reduction of the charge assisting property of the strontium titanate particles of the present invention due to the toner particles.

[Charge control agent]
The toner may also contain a charge control agent, if necessary. As the charge control agent contained in the toner, known ones can be used, but in particular, a metal compound of an aromatic carboxylic acid which is colorless, has a high charge speed of the toner, and can stably maintain a constant charge amount is preferable.

Examples of the negative charge control agent include the following. Metallic salicylate compound, metal naphthoic acid compound, metal dicarboxylic acid compound, polymer compound having sulfonic acid or carboxylic acid in the side chain, polymer compound having sulfonate or sulfonic acid esterified product in the side chain, carboxylate Alternatively, a polymer compound having a carboxylic acid esterified product in the side chain, a boron compound, a urea compound, a silicon compound, or a calix array. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, and an imidazole compound. The charge control agent may be added internally or externally to the toner particles. The amount of the charge control agent added is preferably 0.2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin.

[Developer]
Although the toner of the present invention can be used as a one-component developer, it is preferable to mix it with a magnetic carrier and use it as a two-component developer in order to further improve dot reproducibility. It is also preferable to use it as a two-component developer in that a stable image can be obtained for a long period of time.

As the magnetic carrier, the following known magnetic carriers can be used. Iron powder whose surface has been oxidized, unoxidized iron powder, metal particles such as iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium, and rare earth, their alloy particles, and oxide particles. , A magnetic material-dispersed resin carrier (so-called resin carrier) containing a magnetic material such as ferrite, a magnetic material, and a binder resin that holds the magnetic material in a dispersed state.

When the toner of the present invention is mixed with a magnetic carrier and used as a two-component developer, the mixing ratio with the magnetic carrier at that time is 2% by mass or more and 15% by mass as the toner concentration in the two-component developer. Hereinafter, good results can be obtained when the content is preferably 4% by mass or more and 13% by mass or less.

[Production method]
The method for producing the toner of the present invention is not particularly limited as long as it is a conventionally known toner production method such as an emulsion aggregation method, a melt-kneading method, and a dissolution-suspension method, but a melt-kneading method is preferable from the viewpoint of improving the dispersibility of raw materials. ..

The melt-kneading method is characterized in that a toner composition which is a raw material of toner particles is melt-kneaded and the obtained kneaded product is pulverized. An example of the manufacturing method will be described.

In the raw material mixing step, as a material constituting the toner particles, a polyester resin, a mold release agent, a colorant, and if necessary, other components such as a charge control agent are weighed and blended in a predetermined amount and mixed. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, a mechano hybrid (manufactured by Nippon Coke Industries, Ltd.) and the like.

Next, the mixed materials are melt-kneaded to disperse other raw materials and the like in the binder resin. In the melt-kneading process, batch-type kneaders such as pressurized kneaders and Bambary mixers and continuous-type kneaders can be used, and single-screw or twin-screw extruders have become the mainstream because of the advantage of continuous production. There is. For example, KTK type twin-screw extruder (manufactured by Kobe Steel Co., Ltd.), TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM kneader (manufactured by Ikekai Co., Ltd.), twin-screw extruder (K). -C.K.), Co-kneader (Bus), Kneedex (Nippon Coke Industry Co., Ltd.), etc. can be mentioned. Further, the resin composition obtained by melt-kneading may be rolled with two rolls or the like and cooled with water or the like in the cooling step.

Then, the cooled product of the resin composition is pulverized to a desired particle size in the pulverization step. In the crushing step, for example, after coarse crushing with a crusher such as a crusher, a hammer mill, or a feather mill, the crushing is further performed with a fine crusher. As pulverizers, cryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), super rotor (manufactured by Nisshin Engineering Co., Ltd.), turbo mill (manufactured by Freund Turbo Co., Ltd.) and air jet pulverizer. And so on.

After that, if necessary, inertial classification type elbow jet (manufactured by Nittetsu Mining Co., Ltd.), centrifugal force classification method turboplex (manufactured by Hosokawa Micron Co., Ltd.), TSP separator (manufactured by Hosokawa Micron Co., Ltd.), faculty (manufactured by Hosokawa Micron Co., Ltd.) Classification is performed using a classifier such as (manufactured by Co., Ltd.) or a sieving machine to obtain toner particles.

It is preferable that the weight average particle size of the toner particles is 3.0 μm or more and 5.7 μm or less because the effect of the external additive of the present invention can be sufficiently obtained. Further, the circularity of the toner particles may be increased by applying a mechanical impact force to the particles and performing a heat treatment with hot air or the like. The average circularity of the toner particles is preferably 0.962 or more and 0.972 or less in order to increase the charge transfer opportunity and the frictional rubbing force between the toner particles and increase the charge rising speed.

If necessary, an external additive selected by the above-mentioned production method is added to the toner particles and mixed (externally added). Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, a mechano hybrid (manufactured by Nippon Coke Industries, Ltd.) and the like.

[Image formation method]
The toner set having a color toner and a black toner in which a colorant is contained in the toner of the present invention can be applied to a known image forming method. Specifically, a step of charging the electrostatic charge image carrier, a step of forming an electrostatic charge image on the charged electrostatic charge image carrier, and a step of developing the formed electrostatic charge image with toner to form a toner image. It can be suitably used for an image forming method including a step, a step of transferring the formed toner image to a transfer material, and a step of fixing the transferred toner image to the transfer material to form a fixed image.

The steps of developing the formed electrostatic charge image with toner to form a toner image include a step of forming a black toner image using black toner in the toner set and a step of forming a color toner in the toner set. It suffices to have a step of forming a color toner image by using it. When the color toner is three types of magenta toner, cyan toner, and yellow toner, the process of color toner is three. In the examples described later, cyan toner is represented as the color toner, and an example of using a toner set of black toner and cyan toner is shown.

[Measuring method of weight average particle size (D4) of toner particles]
The weight average particle size (D4) of the toner particles is the same as that of the precision particle size distribution measuring device "Colter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter Co., Ltd.) equipped with a 100 μm aperture tube by the pore electric resistance method. , Measurement with 25,000 effective measurement channels using the attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter Co., Ltd.) for setting measurement conditions and analyzing measurement data. Then, the measurement data is analyzed and calculated.

As the electrolytic aqueous solution used for the measurement, special grade sodium chloride is dissolved in ion-exchanged water so that the concentration becomes about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter Co., Ltd.) can be used. ..

Before performing measurement and analysis, set the dedicated software as follows.
On the "Change standard measurement method (SOM) screen" of the dedicated software, set the total count number of the control mode to 50,000 particles, measure once, and set the Kd value to "Standard particles 10.0 μm" (Beckman). -Set the value obtained using Coulter Co., Ltd.). By pressing the threshold / noise level measurement button, the threshold and noise level are automatically set. Also, set the current to 1,600 μA, the gain to 2, and the electrolyte to ISOTON II, and check the flash of the aperture tube after measurement.

In the dedicated software "Pulse to particle size conversion setting screen", set the bin spacing to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm or more and 60 μm or less.

The specific measurement method is as follows.
(1) Put about 200 mL of the electrolytic aqueous solution in a glass 250 mL round bottom beaker dedicated to Multisizer 3, set it on a sample stand, and stir the stirrer rod counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "aperture flash" function of the analysis software.
(2) Put about 30 mL of the electrolytic aqueous solution in a 100 mL flat-bottomed beaker made of glass, and add about 0.3 mL of the following diluted solution as a dispersant into the electrolytic solution.
-Diluted solution: "Contaminone N" (10% by mass aqueous solution of neutral detergent for cleaning pH 7 precision measuring instruments consisting of nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd. ) Is diluted 3 times by mass with ion-exchanged water. (3) The following ultrasonic disperser with a built-in two oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees and an electrical output of 120 W. A predetermined amount of ion-exchanged water is put into the water tank, and about 2 mL of the detergent N is added to the water tank.
-Ultrasonic disperser: "UltraAsonic Dispension System Stereo A150" (manufactured by Nikkaki Bios Co., Ltd.)
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic solution in the beaker is maximized.
(5) With the electrolytic aqueous solution in the beaker of (4) being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion processing is continued for another 60 seconds. For ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 15 ° C. or higher and 40 ° C. or lower.
(6) Using a pipette, the electrolytic aqueous solution of (5) in which toner is dispersed is dropped onto the round bottom beaker of (1) installed in the sample stand, and the measured concentration is adjusted to about 5%. .. Then, the measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the device, and the weight average particle size (D4) is calculated. The "average diameter" of the analysis / volume statistical value (arithmetic mean) screen when the graph / volume% is set by the dedicated software is the weight average particle diameter (D4).

Hereinafter, the present invention will be described with reference to Production Examples and Examples.
<Production example of silica fine particles>
For the production of silica, the combustion furnace used a hydrocarbon-oxygen mixed burner having a double-tube structure capable of forming an internal flame and an external flame. A two-fluid nozzle for slurry injection is grounded at the center of the burner, and a raw material silicon compound is introduced. (Ii) A flammable gas of hydrocarbon-oxygen is sprayed from around the fluid nozzle to form an internal flame and an external flame which are reducing atmospheres. By controlling the amount and flow rate of flammable gas and oxygen, the atmosphere and temperature, the length of the flame, etc. are adjusted. Silica fine particles are formed from the silicon compound in the flame and further fused until the desired particle size is obtained. Then, after cooling, it is obtained by collecting with a bag filter or the like.

Silica was produced using hexamethylcyclotrisiloxane as a raw material silicon compound, and 100 parts by mass of the obtained inorganic fine particles were surface-treated with a surface treatment agent to obtain silica fine particles. As the surface treatment agent, fatty acids or metal salts thereof, disilylamine compounds, halogenated silane compounds, silicone oils, silane coupling agents, titanium coupling agents and the like are preferable because they can improve the charge stability of the toner. Among them, n-octylethoxysilane treatment, 3,3,3-trifluoropropyltrimethoxysilane treatment, and hexamethyldisilazane treatment are preferable in that the effect of charge stability is further enhanced.

<Manufacturing example of binder resin>
(Production example of polyester resin)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 80.0 mol% of the total number of moles of polyhydric alcohol
-Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 20.0 mol% with respect to the total number of moles of polyhydric alcohol
-Terephthalic acid: 80.0 mol% with respect to the total number of moles of polyvalent carboxylic acid
Trimellitic anhydride: 20.0 mol% with respect to the total number of moles of polyvalent carboxylic acid
The above materials were put into a cooling tube, a stirrer, a nitrogen introduction tube, and a reaction vessel equipped with a thermocouple. Then, 1.5 parts by mass of tin 2-ethylhexanoate (esterification catalyst) was added as a catalyst to 100 parts by mass of the total amount of the monomers. Next, the inside of the flask was replaced with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 2.5 hours while stirring at a temperature of 200 ° C.

Further, the pressure in the reaction vessel was lowered to 8.3 kPA, maintained for 1 hour, cooled to 180 ° C., reacted as it was, and after confirming that the softening point measured according to ASTM D36-86 reached 110 ° C. The temperature was lowered to stop the reaction. The softening point (Tm) of the obtained polyester resin 1 was 115 ° C.

<Manufacturing example of wax dispersant>
In an autoclave reaction vessel equipped with a thermometer and a stirrer, 300.0 parts by mass of xylene and 10.0 parts by mass of polypropylene (melting point 75 ° C.) were placed and sufficiently dissolved. A mixed solution of 5.0 parts by mass of cyclohexyl acid, 12.0 parts by mass of butyl acrylate, and 250.0 parts by mass of xylene was added dropwise at 180 ° C. for 3 hours for polymerization. Further, it was kept at this temperature for 30 minutes, and the solvent was removed to obtain a wax dispersant.

<Toner manufacturing example>
Hereinafter, a production example of cyan toner is shown as a typical example of the color toner.

・ Polyester resin 100.0 parts by mass ・ 3,5-di-t-aluminum salicylate compound 0.1 parts by mass ・ Fisher tropschwax (maximum heat absorption peak temperature 90 ° C) 5.0 parts by mass ・ Wax dispersant 6.5 Mass part ・ C.I. I. Pigment Blue 15: 3 5.0 parts by mass After mixing the raw materials shown in the above formulation with a Henshell mixer (FM75J type, manufactured by Mitsui Miike Machinery Co., Ltd.) at a rotation speed of 20 s ^-1 and a rotation time of 5 minutes. , Kneaded with a twin-screw kneader (PCM-30 type, manufactured by Ikegai Co., Ltd.) set at a temperature of 130 ° C. and a barrel rotation speed of 200 rpm. The obtained kneaded product was cooled and coarsely pulverized with a hammer mill to 1 mm or less to obtain a coarsely crushed product. The obtained coarse crushed product was finely pulverized with a mechanical crusher (T-250, manufactured by Turbo Industries, Ltd.). Further, classification was performed using a rotary classifier (200TSP, manufactured by Hosokawa Micron Co., Ltd.) to obtain toner particles. The operating conditions of the rotary classifier (200TSP, manufactured by Hosokawa Micron) were that the classifying rotor rotation speed was 50.0 s ^-1 . The obtained toner particles had a weight average particle diameter (D4) of 4.9 μm.

To the obtained toner particles, 0.2% by mass of hydrophobic small particle size silica fine particles having a primary average particle size of 10 nm, which was surface-treated with 5.0% by mass of silica fine particles and 10.0% by mass of hexamethyldisilazane, was added. , Henshell mixer (FM75J type, manufactured by Mitsui Miike Kakoki Co., Ltd.), the mixture was mixed at a rotation speed of 15 s ^-1 , a rotation time of 10 minutes, and a jacket temperature of 45 ° C.

Then, after further adding 3.0% by mass of strontium titanate and 0.8% by mass of hydrophobic small particle size silica fine particles having a primary average particle size of 10 nm surface-treated with 10.0% by mass of hexamethyldisilazane. After mixing at a rotation speed of 30 s ^-1 and a rotation time of 4 minutes and a jacket temperature of 20 ° C., the particles were passed through an ultrasonic vibration sieve having an opening of 54 μm to obtain toner 1 having an average circularity of 0.967.

[Manufacturing of toners 2 to 22]
In the production example described above, the weight average particle size of the toner particles, the number average particle size of the toner additive (silica), the charge attenuation constant, and the presence or absence of the surface hydrophobic treatment are adjusted as shown in Table 1. Toners 2 to 22 were obtained in the same manner as in the production example of toner 1.

<Manufacturing example of magnetic core particles>
(Step 1: Weighing / mixing step)
・ Fe ₂ O ₃ 62.7 parts by mass ・ MnCO ₃ 29.5 parts by mass ・ Mg (OH) ₂ 6.8 parts by mass ・ SrCO ₃ 1.0 part by mass Weighed. Then, it was pulverized and mixed for 5 hours with a dry vibration mill using stainless beads having a diameter of 1/8 inch.

-Step 2 (temporary firing step):
The obtained pulverized product was made into pellets of about 1 mm square by a roller compactor. Coarse powder was removed from the pellets with a vibrating sieve having an opening of 3 mm, and then fine powder was removed with a vibrating sieve having an opening of 0.5 mm. Then, using a burner type firing furnace, the calcined ferrite was prepared by firing in a nitrogen atmosphere (oxygen concentration 0.01% by volume) at a temperature of 1,000 ° C. for 4 hours. The composition of the obtained calcined ferrite is as follows.
(MnO) _A (MgO) _b (SrO) _c (Fe ₂ O ₃ ) _d
In the above formula, A = 0.25.7, b = 0.117, c = 0.007, d = 0.393.

(Step 3: Grinding step)
After crushing the obtained calcined ferrite to about 0.3 mm with a crusher, 30 parts by mass of water is added to 100 parts by mass of the calcined ferrite using zirconia beads having a diameter of 1/8 inch, and the wet ball mill is used for 1 hour. Crushed. The slurry was pulverized with a wet ball mill using alumina beads having a diameter of 1/16 inch for 4 hours to obtain a ferrite slurry (a finely pulverized product of calcined ferrite).

(Step 4: Granulation process)
To 100 parts by mass of calcined ferrite, 1.0 part by mass of ammonium polycarboxylate as a dispersant and 2.0 parts by mass of polyvinyl alcohol as a binder were added to the ferrite slurry. Then, using a spray dryer (manufacturer: Okawara Kakoki Co., Ltd.), the particles were granulated into spherical particles. After adjusting the particle size of the obtained particles, the particles were heated at a temperature of 650 ° C. for 2 hours using a rotary kiln to remove organic components of the dispersant and the binder.

(Step 5: Firing step)
In order to control the firing atmosphere, the temperature is raised from room temperature to a temperature of 1,300 ° C. in 2 hours under a nitrogen atmosphere (oxygen concentration 1.00% by volume) in an electric furnace, and then 4 at a temperature of 1,150 ° C. Baked for hours. Then, over 4 hours, the temperature was lowered to 60 ° C., the temperature was returned to the atmosphere from the nitrogen atmosphere, and the calcined product was taken out at a temperature of 40 ° C. or lower.

(Step 6: Sorting step)
After crushing the aggregated particles of the calcined product, the low magnetic force product is cut by magnetic dressing, sieved with a sieve having a mesh size of 250 μm to remove coarse particles, and magnetism with a volume distribution-based median diameter of 37.0 μm. Core particles 1 were obtained.

<Preparation of coating resin>
-Cyclohexyl methacrylate monomer 26.8% by mass
-Methyl methacrylate monomer 0.2% by mass
-Methyl methacrylate macromonomer 8.4% by mass
(Macromonomer having a methacryloyl group at one end and having a weight average molecular weight of 5,000)
・ Toluene 31.3% by mass
・ Methyl ethyl ketone 31.3% by mass
・ Azobisisobutyronitrile 2.0% by mass
Of the above materials, cyclohexyl methacrylate, methyl methacrylate, methyl methacrylate macromonomer, toluene, and methyl ethyl ketone are placed in a four-port separable flask equipped with a reflux condenser, a thermometer, a nitrogen introduction tube, and a stirrer, and nitrogen gas is added. It was introduced and the inside of the system was replaced with nitrogen gas. Then, the mixture was heated to a temperature of 80 ° C., azobisisobutyronitrile was added, and the mixture was refluxed for 5 hours for polymerization. Hexane was injected into the obtained reaction product to precipitate and precipitate a copolymer, and the precipitate was filtered off and then vacuum dried to obtain a coated resin 1. The obtained coating resin 1 was dissolved in 30 parts by mass, 40 parts by mass of toluene, and 30 parts by mass of methyl ethyl ketone to obtain a polymer solution 1 (solid content: 30% by mass).

<Preparation of coating resin solution>
Polymer solution 1 (resin solid content concentration 30%) 33.3% by mass
-Toluene 66.4% by mass
・ Carbon black 0.3% by mass
(Primary particle size 25 nm, nitrogen adsorption specific surface area 94 m ² / g, DBP oil absorption 75 mL / 100 g)
The above material was dispersed in a paint shaker for 1 hour using zirconia beads having a diameter of 0.5 mm. The obtained dispersion was filtered through a 5.0 μm membrane filter to obtain a coated resin solution 1.

[Manufacturing of magnetic carriers]
(Resin coating process)
The coated resin solution 1 was added to a vacuum degassing type kneader maintained at room temperature so as to be 2.5 parts by mass as a resin component with respect to 100 parts by mass of the magnetic core particles 1. After the addition, the mixture was stirred at a rotation speed of 30 rpm for 15 minutes, the solvent was volatilized above a certain level (80% by mass), the temperature was raised to 80 ° C. while mixing under reduced pressure, toluene was distilled off over 2 hours, and then the mixture was cooled. The obtained magnetic carrier was separated into low magnetic force products by magnetic beneficiation, passed through a sieve having an opening of 70 μm, and then classified by a wind power classifier to obtain a magnetic carrier having a volume distribution-based median diameter of 38.2 μm.

[Examples 1 to 17, Comparative Examples 1 to 5]
Mix the toner 1 and the magnetic carrier with a V-type mixer (V-10 type: Tokuju Seisakusho Co., Ltd.) for 0.5 s ^-1 and a rotation time of 5 minutes so that the toner concentration becomes 10% by mass. System developer 1 was obtained. Similarly, the toners 2 to 22 shown in Table 1 and the magnetic carrier were mixed to obtain two-component developeres 2 to 22.

The following printing durability tests were carried out using the two-component developing agents 1 to 17 as Examples 1 to 17 and the two-component developing agents 18 to 22 as Comparative Examples 1 to 5, and then according to (1) to (3). The performance of the toner was evaluated. The specific contents are shown below.

《Printing durability test》
As an image forming apparatus, a Canon digital commercial printing printer imAgeRUNNER ADVANCE C5560 remodeling machine was used, and the two-component developer 1 was put into the developer at the black position. As the modification points of the device, the fixing temperature, the process speed, the DC voltage V _DC of the developer carrier, the charging voltage V _D of the electrostatic latent image carrier, and the laser power were changed so that they could be freely set. In the image output evaluation, an FFh image (solid image) having a desired image ratio is output, and the _VDC , _VD , and laser power are adjusted so that the amount of toner on the FFh image is desired, and the evaluation described later is performed. Was done.

FFh is a value in which 256 gradations are displayed in hexadecimal, 00h is the first gradation (white background portion) of 256 gradations, and FFh is the 256th gradation (solid portion) of 256 gradations. ..

A print durability test was conducted on 15,000 10% image Duty images in a high temperature and high humidity environment (temperature 30 ° C., relative humidity 80%), a developer was collected from the inside of the device, and toner performance was evaluated. ..

<< Toner performance evaluation >>
(1) Coverage measurement paper: CS-680 (680 g / m ² )
(Canon Marketing Japan Inc.)
Evaluation image: 00h image VbAck: 150V on the entire surface of the above A4 paper
(Adjusted by the DC voltage V _DC of the developer carrier, the charging voltage V _D of the electrostatic latent image carrier, and the laser power)
Test environment: High temperature and high humidity environment (temperature 30 ° C / humidity 80% RH)
Fixing temperature: 170 ° C
Process speed: 377 mm / sec
The above evaluation image was output and the fog was evaluated. The fog value was used as the fog evaluation index. Using a reflect meter (REFLEC TIMETER MODEL TC-6DS: manufactured by Tokyo Denshoku), the average reflectance Ds (%) of the evaluation paper before passing the paper is measured. Next, the average reflectance Dr (%) of the evaluation paper after passing the paper is measured. Then, the fog value was calculated using the following formula. The obtained fog value was evaluated according to the following evaluation criteria.
Cover = Dr (%) -Ds (%)
(Evaluation criteria)
Rank A: Cover cover less than 1.0% Rank B: Cover cover 1.0% or more, less than 1.5% Rank C: Cover cover 1.5% or more, less than 2.0% Rank D: Cover cover 2.0% or more, 2 Less than .5% Rank E: Cover 2.5% or more, less than 3.0% Rank F: Cover 3.0% or more

(2) Cohesion measurement:
To measure the degree of cohesion, use a powder leometer (FT4, Freeman Technology Co., Ltd.), weigh 10 g of toner in a predetermined container, stir, and then compact it with a constant pressure to create a high-temperature, high-humidity environment (room temperature 30 ° C., Stored in a humidity of 80%) for 72 hours. After storage, the force when piercing the toner with a special needle jig was measured. The magnitude of the value at this time was used as the evaluation of the degree of cohesion, and the following judgment was made based on the obtained value. The unit of the value of the degree of cohesion is [mJ / mm].
Rank A: Less than 20 Rank B: 20 or more and less than 22 Rank C: 22 or more and less than 24 Rank D: 24 or more and less than 26 Rank E: 26 or more and less than 30 Rank F: 30 or more

(3) Liquidity measurement:
Put 100 g of toner stored in a high temperature and high humidity environment (room temperature 30 ° C, humidity 80%) for 72 hours in a cylindrical container (bottom diameter 15 cm, height 30 cm), and the orientation of the container is changed to 90 degrees / sec. Immediately after applying vibration for 30 seconds, stand the container vertically, remove the lid blocking the 5 cm x 5 cm hole provided at the bottom of the container, measure the amount of toner discharged from the container, and measure this discharge amount. The magnitude of the ratio (%) of was evaluated as the liquidity and was judged as follows.
Rank A: 72% or more Rank B: 68% or more, less than 72% Rank C: 64% or more, less than 68% Rank D: 60% or more, less than 64% Rank E: 50% or more, less than 59% Rank F: 50 The results of performance evaluation of the obtained toner are shown in Table 2.

As shown in the above results, according to the present invention, it is possible to prevent toner aggregation while maintaining toner fluidity and suppress fog of a white background image.

Claims (5)

Toner particles containing a binder resin and toner having silica fine particles on the surface of the toner particles.
The silica fine particles contain silica fine particles A containing an iron atom.
The silica fine particles A have a charge attenuation constant α of 0.0005 after 1800 seconds from being charged in an environment where the number average particle size of the primary particles is 80 nm or more and 200 nm or less and the temperature is 23 ° C. and the relative humidity is 50%. More than 0.0100 or less,
A toner characterized in that the weight average particle size (D4) of the toner particles is 3.0 μm or more and 5.7 μm or less. The toner according to claim 1, wherein the weight average particle size (D4) of the toner is 3.0 μm or more and 5.3 μm or less. The toner according to claim 1 or 2, wherein the silica fine particles A contain 20 ppm or more and 2000 ppm or less of iron atoms. The toner according to claim 3, wherein the silica fine particles A contain 200 ppm or more and 2000 ppm or less of aluminum atoms. The toner according to any one of claims 1 to 4, wherein the silica fine particles A are hydrophobized silica particles.