JP2007147710A - Toner and method for manufacturing the toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent toner image which prevents the generation of aggregate particles formed by aggregation of particles for shells with each other, and obviates image voids by eliminating filming of a photoreceptor surface arising from the aggregate particles, and which prevents an electrostatic charging quantity from changing and is free from image fogging even if printing of a number of sheets is performed by uniformly forming shell layers on the toner particle surfaces. <P>SOLUTION: The toner of a core-and-shell structure formed by making the particles for the shells forming the shell layers adhere to the surfaces of the core particles has polar functional groups, respectively, on the surfaces of the core particles and the surfaces of the particles for the shells and the polarities of both the functional groups are different. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner and a toner manufacturing method.

  In recent years, in copiers and printers, image quality has been improved by employing small-diameter toner. This flow is one of the important themes in the current development, and in order to achieve high image quality, a toner having a smaller diameter is being studied in a manufacturing method called a polymerization method.

  Further, from the viewpoint of reducing toner consumption, studies have been made to increase the amount of colorant in toner particles. However, when the amount of the colorant in the toner particles is increased, the colorant is more easily exposed on the surface of the toner particles, causing a problem that the chargeability of the toner is deteriorated.

  In order to suppress exposure of the colorant to the toner particle surface, a core layer in which a resin layer containing no colorant is salted out / fused on the surface of the core particle containing the resin and the colorant is formed. -Improvement of image quality by using a polymerized toner having a shell structure has been studied (for example, see Patent Document 1).

Also, a three-layer structure in which an intermediate layer having a chargeability opposite to that of the core particle is formed on the surface of the core particles containing a resin and a colorant, and a shell layer having a chargeability opposite to that of the intermediate layer is formed. (See, for example, Patent Document 2).
JP 2002-116574 A JP 2003-91093 A

  However, in the toner produced as in Patent Document 1, since the core particles and the shell particles have the same polarity, the attractive force between the two particles is extremely weak, and as the reaction time elapses, the shell particles It contained aggregate particles formed by aggregation.

  The aggregate particles are easy to film on the surface of the photoreceptor, and this filming causes image white spots.

  Further, as in Patent Document 2, the method of agglomerating shell particles on the surface of the intermediate layer formed by heteroaggregation on the surface of the core particle causes non-uniformity in the formation of the shell layer in part due to rapid aggregation. The layer was exposed on the surface of the toner particles.

  For this reason, when the intermediate layer has a polarity opposite to that of the toner, when the large number of sheets are printed due to the influence of the exposed reverse polarity intermediate layer, the charge amount changes and image fogging occurs.

  The present invention has been made in view of the above problems, and prevents the generation of aggregate particles formed by aggregation of shell particles, and eliminates filming on the surface of the photoreceptor caused by the aggregate particles. To provide a toner that can be obtained with excellent toner images without image blur due to the fact that a shell layer is uniformly formed on the surface of toner particles, and the amount of charge does not change even when many sheets are printed. With the goal.

  The present invention is achieved by adopting the following configuration.

1.
In the toner of the core-shell structure in which the shell particles forming the shell layer are attached to the surface of the core particles,
A toner having polar functional groups on the surface of the core particles and the surface of the shell particles, and the polarities of the functional groups of the two are different.

2.
2. The toner according to 1 above, wherein the surface of the core particle has a compound containing a nitrogen atom.

3.
2. The toner according to 1 above, wherein the surface of the shell particles has a compound containing a nitrogen atom.

4).
In the method for producing a toner having a core / shell structure, the method includes a step of attaching at least particles for shell forming a shell layer to the surface of the core particles.
A method for producing a toner, comprising the step of modifying one of surfaces of the core particles and the shell particles with a functional group.

  The toner of the present invention has an excellent effect that no white spots occur and the charge amount does not change even when a large number of sheets are printed, and image fog does not occur.

  As a result of various studies, the present inventors have found that a toner produced using a core particle surface and a shell particle surface each having a polar functional group and having different polarities of both functional groups has the above problem. I found that it can be solved.

  First, the “problem of white spots” that was the first problem can be improved by eliminating the generation of aggregate particles formed by aggregation of shell particles. This is because core particles whose surface polarity is changed by functional group modification are used, and shell particles having the same polarity as the original core particles are attached to and fused to the core particles with weak electrostatic attraction. It is presumed that the uniform shell layer can be formed before the particles for use are aggregated to form aggregate particles. Therefore, filming on the surface of the photoreceptor due to the aggregate particles does not occur, and generation of image white spots can be suppressed.

  The second problem “change in toner charge amount and occurrence of image fogging” was improved by forming a shell layer uniformly without exposing the core particles to the surface of the toner particles. This is because the core particles and the shell particles are not agglomerated like heteroaggregation but are attached with weak electrostatic attraction as described above. In addition, since the functional group modification of the core particle is not layer formation, even if a component having an opposite polarity is present, the chargeability that is important in image formation by electrophotography is not affected, and high chargeability can be secured. . Therefore, the charge amount does not change over a large number of prints and is stable, and the occurrence of image fog can be suppressed.

  Hereinafter, the present invention will be specifically described.

《Polar functional group》
The polar functional group of the present invention refers to a functional group covalently bonded to the surface of the core particle and a functional group covalently bonded to the surface of the shell particle. In the present invention, polar groups present by adsorption of a surfactant or the like are not applicable.

  Both the core particles and the shell particles used in the present invention have polar functional groups, and the polar functional groups of the core particle surface and the shell particle surface have different polarities.

  Here, the polarities of the polar functional groups possessed by the core particle surface and the shell particle surface are different from each other, preferably a part of one of the particles, preferably a part of the surface of the core particle, having a functional group of opposite polarity. As long as all functional groups of the two do not need to be different.

  Specifically, it is preferable that 10 to 100% of the polar functional groups on the surface of the core particle are modified with reverse polarity, and more preferably 30 to 100% are modified with reverse polarity.

《Functional group modification》
As a specific method for modifying (differentiating) the polarity of the polar functional group on the core particle surface and the shell particle surface,
1. 1. When both the core particle surface and the shell particle surface have a negative-polar functional group, the negative-polar functional group on the core particle surface is modified to be positive with a functional group-modifying compound. 2. When both the core particle surface and the shell particle surface have a negative-polar functional group, the negative-polar functional group on the shell particle surface is modified to be positive with a functional group-modifying compound. 3. When both the core particle surface and the shell particle surface have a positive polarity functional group, a method of modifying the positive polarity functional group on the core particle surface to a negative polarity with a functional group-modifying compound. When both the core particle surface and the shell particle surface have a positive polarity functional group, there is a method of modifying the positive polarity functional group of the shell particle surface to a negative polarity with a compound that modifies the functional group, a method for producing a toner, An appropriate method can be selected depending on the image forming method and the like.

  The compound used for modifying the functional group on the particle surface is not particularly limited as long as it contains a functional group having a polarity opposite to the functional group on the particle surface and can react with the functional group on the particle surface.

  Examples of the negative electrode functional group include a carboxyl group, a hydroxyl group, a halogen-containing group, and a sulfone group. Among these, a carboxyl group and a hydroxyl group are preferable.

  Examples of positive functional groups include amino groups and secondary and tertiary amines substituted with hydrogen, or cationic groups such as amide groups and trimethylammonium groups. Among these, amino groups and amines It preferably contains a nitrogen atom such as trimethylammonium.

  The polarity of the core particle surface is preferably negative in the case of an emulsion-associative toner. When the polarity of the core particle surface has a negative polarity functional group, either an amino group or a cationic group such as a secondary amine, a tertiary amine or a trimethylammonium group substituted with an amino group as a reverse polarity functional group is used. What you have is good. These may be used alone or in combination of two or more.

  When the polar functional group on the surface of the core particle is negative, the compound used for functional group modification is preferably a compound containing a nitrogen atom.

  FIG. 1 is a schematic diagram showing an example of a method in which both the core particle surface and the shell particle surface have a negative-polar functional group, and the functional group on the core particle surface is modified to a positive polarity by a functional group-modifying compound.

  In FIG. 1, 1 is a core particle, 2 is a particle for shell, 3 is a shell layer, 11 is a functional group on the surface of the core particle, 12 is a modified functional group on the surface of the core particle, and 13 is a functional group on the surface of the particle for shell Represents.

  Table 1 lists examples of compounds used for functional group modification when the surface of the core particle is negative, but the present invention is not limited thereto.

<Production of toner>
Next, the toner of the present invention will be described.

  The toner of the present invention preferably has a core-shell structure in which the core particles are formed and then the surface of the core particles is modified with a functional group, and a shell is provided on the surface.

  The core particle of the toner having a core / shell structure is a composite resin particle having a multilayer structure prepared by a suspension polymerization method, or a composite resin particle having a multilayer structure called emulsion polymerization, particularly a multistage polymerization method. It is obtained by agglomerating and fusing together with particles (or colored resin particles) in the presence of an aggregating agent. Then, the functional group modification of the core particle surface of the composite resin particles and the colored resin particles formed in this way is performed, and the shelling operation is further performed on the surface using a separately prepared resin particle dispersion, At least one shell is formed. In this way, a shell made of resin fine particles is formed by performing a shelling operation on the surface of the core particles to form toner particles having a core / shell structure.

  Then, an external additive is added to the formed toner particles as necessary to produce the toner of the present invention.

  The mass ratio of the core particle and the shell layer (which may be a single layer or a plurality of layers) of the toner of the present invention is preferably 10 to 30% by mass with respect to the mass of the core particle.

  Next, a method for producing the toner of the present invention will be described.

The toner of the present invention is produced, for example, through the following steps.
(1) Release agent dissolution / dispersion step in which release agent is dissolved or dispersed in radical polymerizable monomer (2) Polymerization step (3) for preparing a dispersion of core resin particles (resin fine particles) Aggregation and fusion process in which core resin particles (resin fine particles) and colorant particles are agglomerated and fused in an aqueous medium to obtain core particles (associate particles) (4) Aging of core particles (associate particles) with thermal energy The first aging step for adjusting the shape (5) The functional group modification step for modifying the polar functional group on the surface of the aged core particle (6) In the core particle (associate particle) dispersion liquid whose surface is functionally modified Shell forming step in which the core particle is added to the surface of the core particles, and the core particles are adhered and fused to form toner particles having the core / shell structure. (7) The core / shell structure toner particles are heated. Aged with energy, core / shell structure Second ripening step for adjusting the shape of the toner particles (8) Cooling step for cooling the toner particle dispersion to complete the ripening (9) The toner particles are solid-liquid separated from the cooled toner particle dispersion, and the toner Solid-liquid separation for removing surfactants from the particles, washing step (10) Drying step for drying the washed toner particles. If necessary, after the drying step,
(11) There may be a step of adding an external additive to the dried toner particles.

  Subsequently, each step will be described in detail.

[Mold release agent dissolution / dispersion process]
This step is a step of preparing a radical polymerizable monomer solution in which a release agent compound is dissolved in a radical polymerizable monomer and the release agent compound is mixed.

[Polymerization process]
In a preferred example of this polymerization step, a radical polymerizable monomer solution containing the release agent compound dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less is added. Then, mechanical energy is applied to form droplets, and then a water-soluble radical polymerization initiator is added to proceed the polymerization reaction in the droplets. An oil-soluble polymerization initiator may be contained in the droplet. In such a polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the mechanical energy applying means include strong stirring such as homomixer, ultrasonic wave, and manton gorin or ultrasonic vibration energy applying means.

  By this polymerization step, resin fine particles containing a release agent compound and a binder resin are obtained. Such resin fine particles may be colored fine particles or non-colored fine particles. The colored resin fine particles can be obtained by polymerizing a monomer composition containing a colorant. In the case of using uncolored resin fine particles, a dispersion of colorant fine particles is added to the dispersion of resin fine particles in the agglomeration / fusion process described later to melt the resin fine particles and the colorant fine particles. By applying it, toner particles can be obtained.

[Aggregation / fusion process] (including the first aging process)
As the aggregation and fusion method in the fusion step, a salting out / fusion method using resin fine particles (colored or non-colored resin fine particles) obtained in the polymerization step is preferable. In the agglomeration / fusion step, the internal additive fine particles such as the release agent fine particles and the charge control agent can be agglomerated and fused together with the resin fine particles and the colorant fine particles.

  The “aqueous medium” in the agglomeration / fusion step is one in which the main component (50% by mass or more) is made of water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

The colorant fine particles can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gorin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, or the like. Examples thereof include a medium type disperser. Moreover, a general thing can be used as surfactant used. The colorant (fine particles) may be surface-modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the molecular weight solution, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  The salting out / fusing method, which is a preferred agglomeration and fusing method, is a salting out method comprising an alkali metal salt, an alkaline earth metal salt, a trivalent salt, or the like in water in which resin fine particles and colorant fine particles are present. An agent is added as an aggregating agent having a critical agglomeration concentration or higher, and then salting-out proceeds by heating to a temperature not lower than the glass transition temperature of the resin fine particles and not lower than the melting peak temperature (° C.) of the mixture. At the same time, it is a process of fusing. Here, the alkali metal salt and alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used.

  When agglomeration and fusion are performed by salting out / fusion, it is preferable to make the time allowed to stand after adding the salting-out agent as short as possible. The reason for this is not clear, but there are problems that the aggregation state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. appear. The temperature for adding the salting-out agent needs to be at least the glass transition temperature of the resin fine particles. The reason for this is that if the temperature at which the salting-out agent is added is equal to or higher than the glass transition temperature of the resin fine particles, the salting out / fusion of the resin fine particles proceeds rapidly, but the particle size cannot be controlled. There arises a problem that particles having a particle size are generated. Although the range of this addition temperature should just be below the glass transition temperature of resin, generally it is 5-55 degreeC, Preferably it is 10-45 degreeC.

  Further, the salting-out agent is added at a temperature not higher than the glass transition temperature of the resin fine particles, and then the temperature is raised as quickly as possible to a temperature not lower than the glass transition temperature of the resin fine particles and not lower than the melting peak temperature (° C.) of the mixture. Heat to. The time until this temperature rise is preferably less than 1 hour. Further, although it is necessary to quickly raise the temperature, the rate of temperature rise is preferably 0.25 ° C./min or more. The upper limit is not particularly clear, but if the temperature is increased instantaneously, salting out proceeds rapidly, so there is a problem that particle size control is difficult, and 5 ° C./min or less is preferable. By this fusing step, a dispersion of associated particles (core particles) formed by salting out / fusing resin fine particles and arbitrary fine particles is obtained.

[Functional group modification step]
In the functional group modification step, the formed core particle solution is cooled, and the pH is adjusted to 9.0 or higher, preferably 10.5 or higher with an aqueous sodium hydroxide solution, and then the compound used for functional group modification is ion-exchanged. A solution dissolved in water is added under stirring, and the polar functional group on the surface of the core particle is modified with the compound to produce a functional-modified core particle. The reaction temperature and treatment time for functional group modification are not particularly limited as the reaction proceeds, but the reaction temperature is preferably at least room temperature and below the core particle growth temperature.

[Shelling process] (Including second aging process)
In the shelling step, the resin particle dispersion for shell is added to the core particle dispersion having a modified functional group, and the resin particles for shell are adhered and fused to the surface of the core particles, and the shell particles are adhered to the surface of the core particles. Resin particles are coated to form toner particles.

  Specifically, the core particle dispersion liquid modified with the functional group is added with the dispersion liquid of the resin particles for the shell while maintaining the temperature in the aggregation / fusion process and the first aging process, and the heating and stirring are continued. Then, the resin particles for shell are coated on the surface of the core particles to form toner particles. Then, when the toner particles have reached a predetermined particle size due to shelling, a stopper such as sodium chloride is added to stop the particle growth, and then the resin particles for the shell adhered to the core particles are fused. Continue to stir for several hours. In this way, resin particles are fixed to the surface of the core particles to form a shell, and toner particles having a uniform shape are formed.

[Aging process]
In the present invention, it is possible to produce a rounded toner having a uniform shape through the above-described steps. Further, it is possible to control the shape of the toner particles in the true sphere direction by setting the time of the second aging step longer or by setting the aging temperature higher.

[Cooling process]
This step is a step of cooling (rapid cooling) the toner particle dispersion. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

[Solid-liquid separation and washing process]
In the solid-liquid separation / washing step, the solid-liquid separation process for solid-liquid separation of the toner particles from the dispersion of the toner particles cooled to a predetermined temperature in the above-described step, and the solid-liquid separated toner cake (in a wet state) A cleaning process is performed to remove deposits such as a surfactant and a salting-out agent from an aggregate obtained by agglomerating certain toner particles in a cake form. Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

[Drying process]
In this step, the washed toner cake is dried to obtain dried toner particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The moisture of the dried toner particles is preferably 5% by mass or less, more preferably 2% by mass or less. In addition, when the toner particles subjected to the drying treatment are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

[External process]
This step is a step of preparing a toner by mixing the dried toner particles with an external additive as necessary.

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

The average particle size of the toner of the present invention is preferably 3 to 9 μm in terms of median particle size (D ₅₀ ) on a volume basis. The volume-based median particle size (D ₅₀ ) is measured and calculated using a device in which a computer system for data processing (Beckman Coulter, Inc.) is connected to “Coulter Multisizer III” (Beckman Coulter, Inc.). can do.

As a measurement procedure, 0.02 g of toner is blended with 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing the toner). After that, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion. This toner dispersion is poured into a beaker containing ISOTON II (manufactured by Beckman Coulter) in a sample stand with a pipette until the measured concentration reaches 5 to 10%, and the measuring machine count is 300.
Set to 00 and measure. The aperture diameter of the Coulter Multisizer was 100 μm.

  The toner of the present invention can be used as a black toner or a color toner.

  Next, the compounds (binder resin, colorant, release agent, charge control agent, external additive, lubricant) constituting the toner of the present invention will be described.

(Binder resin)
As the polymerizable monomer constituting the binder resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichloro are used. Styrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn -Styrene or styrene derivatives such as decylstyrene, pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-methacrylate Octyl, 2-ethylhexyl methacrylate, stearyl methacrylate Methacrylic acid ester derivatives such as lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, etc., acrylate derivatives, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride and vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. Examples include vinyl compounds, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers can be used alone or in combination.

  Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Furthermore, multifunctional such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carboxyl). Nitriles), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4- t-butylperoxycyclohexyl) propane, tris- Peroxide polymerization initiator or a peroxide such as t- butylperoxy) triazine and the like polymeric initiator having a side chain.

  Moreover, when using an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

(Coloring agent)
As the colorant used in the present invention, a known inorganic or organic colorant can be used. Specific colorants are shown below.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  Examples of the colorant for magenta or red include 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. And CI Pigment Red 222.

  Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, 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 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the colorant for green or cyan include 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 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  These colorants may be used alone or in combination of two or more as required. The addition amount of the colorant is set in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

(Release agent)
Examples of the mold release agent used in the present invention include polyethylene wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, dialkyl ketone wax such as distearyl ketone, carnauba wax, montan wax, trimethylolpropane tri Behenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tri Ester waxes such as meristate tristearyl and distearyl maleate, ethylene diamine dibehenyl amide, and trimellitic acid tristearyl amide Such as system wax, and the like.

  Especially, as a mold release agent melting | fusing point, a thing whose melting | fusing point is 50-100 degreeC is preferable.

  The addition amount of the release agent is preferably 1 to 15% by mass and more preferably 3 to 12% by mass with respect to the whole toner.

(Charge control agent)
A charge control agent can be added to the toner of the present invention as necessary. As the charge control agent, known compounds can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid Examples thereof include a metal salt or a metal complex thereof. Examples of the metal contained include Al, B, Ti, Fe, Co, and Ni. Particularly preferred as the charge control agent is a metal complex compound of a benzylic acid derivative. In addition, when the content of the charge control agent is preferably 0.1 to 20.0% by mass with respect to the whole toner, good results can be obtained.

(External additive)
The toner of the present invention is preferably prepared by adding an external additive. The addition amount of the external additive is preferably 0.1 to 10.0% by mass with respect to the whole toner.

  The external additive is not particularly limited, and known inorganic fine particles, organic fine particles, lubricants and the like can be used.

  Examples of the inorganic fine particles include general particles such as silica, titania, alumina, and strontium titanate particles.

  Examples of the organic particles include particles such as polystyrene, polymethyl methacrylate, styrene-methyl methacrylate copolymer, benzoguanamine, and melamine.

  As the large-sized inorganic particles, a dope such as titanium-doped silica is preferably used, and these inorganic particles are preferably hydrophobized with a silane coupling agent, a titanium coupling agent, or the like.

  Examples of the lubricant include metal salts of higher fatty acids. Specific examples of the metal salts of such higher fatty acids include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate, and the like; zinc oleate, manganese oleate, iron oleate, olein Oleic acid metal salts such as acid copper and magnesium oleate; palmitate metal salts such as zinc palmitate, copper palmitate, magnesium palmitate and calcium palmitate; linoleic acid metal salts such as zinc linoleate and calcium linoleate; ricinol Examples include ricinoleic acid metal salts such as zinc acid and calcium ricinoleate.

<Developer>
The toner of the present invention can be used as a one-component developer or a two-component developer. When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to. Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials typified by iron-containing magnetic particles such as iron, ferrite, and magnetite can be used as the magnetic particles of the carrier, but ferrite particles or magnetite particles are particularly preferable. The magnetic particles preferably have a volume average particle diameter of 15 to 100 μm, more preferably 20 to 80 μm.

  The volume average particle diameter of the carrier can be measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathetic).

The carrier is preferably a coating carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicon resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  The mixing ratio of the carrier and the toner is preferably in the range of carrier: toner = 1: 1 to 50: 1 by mass ratio.

<Image forming apparatus>
FIG. 2 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus used in the present invention.

  This image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and paper feeding It comprises a conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y, and a developing unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A unit (developing step) 4Y, a primary transfer roller 5Y as a primary transfer unit (primary transfer step), and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C and 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 5Y, 5M, 5C and 5Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arrayed in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  Next, FIG. 3 shows a color image forming apparatus using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means, and an intermediate transfer body around the organic photoreceptor. Or a laser beam printer). The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 1 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed.

  In the rotation process, the photoreceptor 1 is uniformly charged to a predetermined polarity and potential by a charging means (charging process) 2, and then time-series electric digital of image information by an image exposure means (image exposure process) 3 (not shown). An electrostatic latent image corresponding to the yellow (Y) color component image (color information) of the target color image is formed by receiving image exposure by scanning exposure light or the like by a laser beam modulated in accordance with the pixel signal. The

Then, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means: developing step (yellow color developing device) 4Y. At this time, the second to fourth developing means (
(Magenta color developer, cyan color developer, black color developer) 4M, 4C, and 4Bk are inactive and do not act on the photoreceptor 1, and the yellow toner image of the first color is It is not affected by the second to fourth developing devices.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is driven to rotate in the clockwise direction at the same peripheral speed as the photosensitive member 1.

  The yellow toner image of the first color formed and supported on the photosensitive member 1 is applied to the intermediate transfer member 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photosensitive member 1 and the intermediate transfer member 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoreceptor 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 6a.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 5b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  The primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 1 to the intermediate transfer member 70 has a polarity opposite to that of the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 1 to the intermediate transfer member 70, the secondary transfer roller 5b and the intermediate transfer member cleaning means 6b can be separated from the intermediate transfer member 70. .

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred to the transfer material P which is the second image carrier, the secondary transfer roller 5b is brought into contact with the belt of the intermediate transfer member 70. At the same time, the transfer material P is fed from the pair of paper registration rollers 23 through the transfer paper guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 5b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 5b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 24 and fixed by heating.

  The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

<< Production of Toner 1 >>
(Preparation of core resin particles)
First stage polymerization (mini-emer polymerization)
183 g of styrene
60 g of n-butyl acrylate
Acrylic acid 7g
n-octyl-3-mercaptopropionate 7 g
Is added to a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, and 100 g of pentaerythritol tetrabehenate is added thereto, heated to 70 ° C. and dissolved. A monomer solution was prepared.

  On the other hand, a surfactant solution in which 2 g of polyoxyethylene (2) sodium dodecyl ether sulfate is dissolved in 1350 g of ion-exchanged water is heated to 70 ° C., added to and mixed with the monomer solution, and then a machine having a circulation path. Dispersion was carried out at 70 ° C. for 30 minutes using a type disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) to prepare an emulsified dispersion.

  Next, an initiator solution in which 7.5 g of potassium persulfate is dissolved in 150 g of ion-exchanged water is added to this emulsified dispersion, and polymerization is performed by heating and stirring the system at 78 ° C. for 1.5 hours. Resin particles were obtained. This is designated as “resin particles (1)”.

Second stage polymerization (formation of outer layer)
To the “resin particles (1)” obtained above, an initiator solution in which 12 g of potassium persulfate is dissolved in 220 g of ion-exchanged water is added, and at a temperature of 80 ° C.,
342 g of styrene
n-Butyl acrylate 100g
Acrylic acid 13g
n-octyl-3-mercaptopropionate 7.5 g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles. These resin particles are referred to as “core resin particles”.

(Preparation of resin particles for shell)
In a reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introduction device, a surfactant solution dissolved in 8 g of sodium dodecyl sulfate and 3000 g of ion-exchanged water was charged, and stirred at a stirring speed of 230 rpm under a nitrogen stream. The liquid temperature was raised to 80 ° C.

  To this surfactant solution, an initiator solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, the temperature of the solution was adjusted to 80 ° C., and the following monomer mixture was added dropwise over 100 minutes. Polymerization was performed by heating and stirring the system at 80 ° C. for 2 hours to prepare “resin particles for shell”.

Styrene 570g
165 g of n-butyl acrylate
Methacrylic acid 70g
n-octyl-3-mercaptopropionate 5.5 g
(Preparation of colorant dispersion)
90 g of sodium dodecyl sulfate was dissolved in 1600 g of ion-exchanged water with stirring. While stirring this solution, 420 g of carbon black “Regal 330R” (manufactured by Cabot) is gradually added, and then dispersed using a mechanical disperser “CLEAMIX” (manufactured by Mtechnics). A dispersion of colorant particles was prepared. This is referred to as a “colorant dispersion”.

(Production of core particles)
Core resin dispersion 2000 g
670 g of ion exchange water
Colorant dispersion 400g
The above was put in a reaction vessel equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device, and the temperature was adjusted to 30 ° C. Then, a 5N sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10. It was adjusted.

Next, an aqueous solution in which 60 g of magnesium chloride hexahydrate was dissolved in 60 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes to grow the particle size and carry out an association reaction. In this state, the particle size of the associated particles was measured with “Coulter Multisizer III” (manufactured by Beckman Coulter), and when the median particle size (D ₅₀ ) on the volume basis became 5.5 μm, sodium chloride An aqueous solution in which 8.5 g was dissolved in 35 g of ion-exchanged water was added to stop particle growth. Thereafter, the mixture was heated and stirred at 95 ° C. for 2 hours, and aged to a circularity suitable for functional group modification and shelling to prepare a “core particle dispersion”.

(Functional group modification process)
Next, the “core particle dispersion” is cooled to 70 ° C., 5N aqueous sodium hydroxide solution is added to adjust the pH to 11.0, and 37 g of “glycidyltrimethylammonium chloride” is dissolved in an equal amount of ion-exchanged water. The solution thus added was added over 5 minutes with stirring and then reacted for 10 minutes to modify the functional groups on the surface of the core particles (association particles).

(Shelling, aging, cooling process)
Thereafter, the pH is adjusted to 7.0 with 1N hydrochloric acid, the temperature is raised to 90 ° C., 260 g of “resin particles for shell” are added, and heating and stirring are continued for 1 hour, and the functional group-modified core particle surfaces The resin particles for the shell were adhered and fused to each other. Here, an aqueous solution in which 17 g of sodium chloride was dissolved in 70 g of ion-exchanged water was added to stop the particle growth, and then the mixture was heated and stirred at 95 ° C. to ensure the fusion of the resin particles for the shell and the circularity of the toner. Aged. When the desired circularity was reached, the mixture was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped to obtain a “toner base particle dispersion”.

(Solid-liquid separation / washing / drying process)
The toner particle base in the “toner base particle dispersion” obtained above is solid-liquid separated with a basket type centrifugal separator “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.), and the toner base particle wet A cake was formed. The wet cake was washed with ion exchange water at 40 ° C. until the electric conductivity of the filtrate reached 5 μS / cm by the basket type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner was dried until the amount became 0.5% by mass to prepare “toner base particles”.

(Preparation of Toner 1)
1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the “toner base particles” obtained above. “Toner 1” was prepared by mixing with a Henschel mixer.

(Preparation of Toner 2)
“Toner 2” was prepared in the same manner except that 37 g of “glycidyltrimethylammonium chloride” used in the preparation of “Toner 1” was changed to 22 g.

(Preparation of Toner 3)
“Toner 3” was prepared in the same manner except that 37 g of “glycidyltrimethylammonium chloride” used in the preparation of “Toner 1” was changed to 7 g.

(Preparation of Toner 4)
“Toner 4” was prepared in the same manner except that 37 g of “glycidyltrimethylammonium chloride” used in the preparation of “Toner 1” was changed to 29 g of “hexamethylenediamine”.

(Preparation of Toner 5)
“Toner 5” was prepared in the same manner except that 29 g of “hexamethylenediamine” used in the preparation of “Toner 4” was changed to 17 g.

(Production of Toner 6)
“Toner 6” was prepared in the same manner except that 29 g of “hexamethylenediamine” used in the preparation of “Toner 4” was changed to 6 g.

(Preparation of Toner 7)
The resin particles for core, the resin particles for shell, and the colorant dispersion were prepared in the same manner as “Toner 1”.

(Production of core particles)
Core resin dispersion 2000 g
670 g of ion exchange water
Colorant dispersion 400g
The above was put in a reaction vessel equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device, and the temperature was adjusted to 30 ° C. Then, a 5N sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10. It was adjusted.

Next, an aqueous solution in which 60 g of magnesium chloride hexahydrate was dissolved in 60 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was started to rise, and this system was heated to 90 ° C. over 60 minutes to carry out a particle growth reaction. In this state, the particle size of the associated particles was measured with “Coulter Multisizer III” (manufactured by Beckman Coulter), and when the median particle size (D ₅₀ ) on the volume basis became 5.5 μm, sodium chloride An aqueous solution in which 8.5 g was dissolved in 35 g of ion-exchanged water was added to stop particle growth. Thereafter, the mixture was heated and stirred at 95 ° C. for 2 hours, and aged to a circularity suitable for shelling to produce “core particle dispersion 7”.

  Next, after the “core particle dispersion 7” is cooled to 90 ° C., 260 g of “shell resin particles” are added, and heating and stirring are continued for 3 hours to adhere and fuse the shell resin particles to the surface of the core particles. I let you. Here, an aqueous solution in which 17 g of sodium chloride was dissolved in 70 g of ion-exchanged water was added to stop the particle growth, and then the mixture was heated and stirred at 95 ° C. to ensure the fusion of the resin particles for the shell and the circularity of the toner. It was. When the desired circularity was reached, the mixture was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and the stirring was stopped to obtain “Toner Base Particle Dispersion 7”.

(Washing / drying process)
The toner particle matrix in the “toner matrix particle dispersion 7” obtained above is solid-liquid separated with a basket type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.). A wet cake was formed. The wet cake was washed with ion exchange water at 40 ° C. until the electric conductivity of the filtrate reached 5 μS / cm by the basket type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner was dried until the amount became 0.5% by mass to prepare “toner base particles 7”.

  1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the “toner base particle 7” obtained above. Then, “Toner 7” was prepared by mixing with a Henschel mixer.

(Production of Toner 8)
The resin particles for core, the resin particles for shell, and the colorant dispersion were prepared in the same manner as “Toner 1”.

(Preparation of resin particles for intermediate layer)
In a reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introduction device, a surfactant solution dissolved in 8 g of sodium dodecyl sulfate and 3000 g of ion-exchanged water was charged, and stirred at a stirring speed of 230 rpm under a nitrogen stream. The liquid temperature was raised to 80 ° C.

  To this surfactant solution, an initiator solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, the temperature of the solution was adjusted to 80 ° C., and the following monomer mixture was added dropwise over 100 minutes. The system was polymerized by heating and stirring at 80 ° C. for 2 hours to prepare “resin particles for intermediate layer”.

Styrene 570g
n-Butyl acrylate 100g
Dimethylaminoethyl acrylate 135g
10 g of n-octyl-3-mercaptopropionate
(Production of core particles)
Core particle dispersion 2000g
670 g of ion exchange water
Colorant dispersion 400g
The above was put in a reaction vessel equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device, and the temperature was adjusted to 30 ° C. Then, a 5N sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10. It was adjusted.

Next, an aqueous solution in which 60 g of magnesium chloride hexahydrate was dissolved in 60 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes to grow the particle size and carry out an association reaction. In this state, the particle size of the associated particles was measured with “Coulter Multisizer III” (manufactured by Beckman Coulter), and when the median particle size (D ₅₀ ) on the volume basis became 5.5 μm, sodium chloride An aqueous solution in which 8.5 g was dissolved in 35 g of ion-exchanged water was added to stop particle growth. Thereafter, the mixture was heated and stirred at 95 ° C. for 2 hours, and aged to a circularity suitable for shelling to produce “core particle dispersion 8”.

  Next, after cooling the “core particle dispersion 8” to 80 ° C., 130 g of “interlayer resin particles” are added and reacted for 30 minutes, and then 260 g of “shell resin particles” are added over 1 hour. Heating and stirring were continued, and the resin particles for the intermediate layer and the resin particles for the shell were adhered and fused to the core particle surfaces. Here, an aqueous solution in which 17 g of sodium chloride was dissolved in 80 g of ion-exchanged water was added to stop the particle growth, and then the mixture was heated and stirred at 95 ° C. to ensure the fusion of the resin particles for the shell and the circularity of the toner. It was. When the desired circularity was reached, the mixture was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and the stirring was stopped to obtain “Toner Base Particle Dispersion 8”.

(Washing / drying process)
The toner particle matrix in the “toner matrix particle dispersion 8” obtained above was subjected to solid-liquid separation with a basket type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.). A wet cake was formed. The wet cake was washed with ion exchange water at 40 ° C. until the electric conductivity of the filtrate reached 5 μS / cm by the basket type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner was dried until the amount became 0.5% by mass to prepare “toner base particles 8”.

  1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the “toner base particle 8” obtained above. Then, “Toner 8” was prepared by mixing with a Henschel mixer.

  Table 2 shows the functional group-modified compounds used for the functional group modification of the toner prepared above and the amount thereof added, the presence / absence of positive functional groups in the core particles, and the polar functional groups in the resin particles for shells.

<Production of developer>
Each of the “toners 1 to 8” produced above is mixed with a silicon carrier-coated ferrite carrier having a median particle diameter (D ₅₀ ) of 60 μm on a volume basis, and a “developer having a toner concentration of 6% by mass”. 1-8 "were produced.

《Image evaluation device》
As the image evaluation device, “bizhub PRO C550” (manufactured by Konica Minolta Business Technologies) was used.

《Image evaluation》
Image evaluation was performed for the following items in an environment of 33 ° C. and 80% RH in which the toner and the developer prepared above were sequentially loaded in the black developing device of the image evaluation device.

It should be noted that the print is an image with a pixel rate of 10% (original image with 7% character image, human face photo, solid white image, and solid black image divided into 1/4 each) in a single intermittent mode. , 000 A4 quality paper (64 g / m ² ).

<Image white>
After printing 10,000 sheets, one solid image was printed on A3 quality fine paper (64 g / m ² ), and white spots on the solid image due to filming on the surface of the photoreceptor were visually evaluated.

Evaluation Criteria A: No occurrence of white spots in the image ○: White spots in the image of 10 to 10 occurred Δ: White spots in the image of 1 to 20 places occurred ×: White spots in the area of 21 or more occurred.

<Charge amount change range>
Regarding the amount of change in charge amount, during printing of the image evaluation, after 100 sheets were printed and after 9000 sheets were printed, the developer was sampled from the developing device, and the charge amount of the collected developer was measured. The change amount of the charge amount is a value obtained by subtracting the charge amount after printing 9,000 sheets from the charge amount after printing 100 sheets.

The charge amount (μC / g) was measured using a blow-off charge amount measuring device “TB-200” (manufactured by Toshiba Chemical Co., Ltd.) equipped with a 400-mesh stainless steel screen, and a blow pressure of 4.9 × 10 ⁴ Pa (0 .5 kgf / cm ² ) for 10 seconds and blown with nitrogen gas, and the measured charge was divided by the flying toner mass.

<Image fog>
Image fog was evaluated as follows.

  First, using a reflection densitometer “RD-918” (manufactured by Macbeth Co., Ltd.), the absolute image density at 20 locations is measured and averaged to obtain a “blank paper density”. Next, with respect to the white background portion of the 10000th printed image, the absolute image densities at 20 locations are measured in the same manner as the white paper and averaged to be “white background density”. “Image fog” is a value obtained by subtracting the white paper density from the white background density of the print image.

Evaluation criteria A: Image fog is 0.003 or less. B: Image fog is less than 0.003 to less than 0.006. Δ: Image fog is less than 0.006 to less than 0.010. X: Image fog is greater than 0.010.

  Table 3 shows the evaluation results.

  As can be seen from Table 3, “Toners 1 to 6” of “Examples 1 to 6” are excellent in all evaluation items, but “Toners 7 and 8” of “Comparative Examples 1 and 2” are evaluation items. It turns out that there are some problems.

An example of a process for producing the toner of the present invention will be described. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core particle 2 Resin particle for shells 3 Shell layer 11 Functional group on the surface of core particle 12 Functional group modified by functional group on the surface of core particle 13 Functional group on the surface of resin particle for shell

Claims (4)

In the toner of the core-shell structure in which the shell particles forming the shell layer are attached to the surface of the core particles,
A toner having polar functional groups on the surface of the core particles and the surface of the shell particles, and the polarities of the functional groups of the two are different. The toner according to claim 1, wherein the surface of the core particle has a compound containing a nitrogen atom. The toner according to claim 1, wherein the surface of the shell particles has a compound containing a nitrogen atom. In the method for producing a toner having a core / shell structure, the method includes a step of attaching at least particles for shell forming a shell layer to the surface of the core particles.
A method for producing a toner, comprising the step of modifying one of surfaces of the core particles and the shell particles with a functional group.

Images