JP2013130633A - Manufacturing method of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a toner having excellent heat-resistance storage stability.SOLUTION: Provided is a manufacturing method of a toner containing at least resin and a mold release agent including steps of aggregation and fusion. The manufacturing method further includes an aging step, and a step of adding a solvent to an associated liquid upon completion of the aging step and decreasing a liquid temperature by 3 to 35°C at a cooling rate of 0.1 to 30°C/min. The SP value of the solvent is 12 to 24; the melting point of the mold release agent is 60 to 110°C; and the kinetic viscosity of the mold release agent is 6 to 20 mm/sec.

Description

  The present invention relates to a toner manufacturing method.

  In recent years, with the progress of color and speedup of copiers, the electrophotographic industry demands low-cost, high-quality and environmentally friendly toners. In order to satisfy this requirement, conversion from conventional pulverized toner to chemical toner is progressing. Various methods for producing chemical toners have been studied, and products are marketed by several methods. However, due to the cost reduction of copiers and printers equipped with toner, there is an increasing demand for toner characteristics to obtain high image quality.

  In particular, a method for producing toner particles by aggregating and fusing resin particles, release agent particles, colorant particles, and the like prepared by an emulsion polymerization method has a narrow particle size distribution while having a small particle size. Therefore, high-quality images can be expected, and the toner particles are attracting attention for reasons such as having moderate irregularities and good cleaning properties (for example, Patent Document 1).

JP 2008-04-0055 A

  The method for producing a toner to be agglomerated and fused as described above usually includes a step of aggregating and fusing under heating and aging to produce associated particles, and then cooling the associated liquid to near room temperature. However, if the temperature of the associated liquid is lowered by cooling the container after aging, so-called slow cooling, the shape changes with crystallization near the melting point of the release agent (wax), or the release agent There is a problem that the toner particles are deposited on the surface of the toner and the circularity of the toner particles is reduced (deformation). On the other hand, in the method of quenching using a heat exchanger as described in Patent Document 1, the change in the shape of the release agent can be reduced and the toner particles can be prevented from being deformed. There is a problem that it is not possible to completely prevent the toner particles from oozing out onto the surface of the toner particles, and this causes fusion (unification) of the particles. Such deformation of the toner particles and fusion of the particles cause a decrease in the heat resistance of the toner.

  Accordingly, an object of the present invention is to provide a method for producing a toner that is excellent in heat-resistant storage stability by suppressing deformation of toner particles and fusion of particles.

  The present inventors have conducted intensive research to solve the above problems. As a result, in the step of producing a toner containing a release agent having a predetermined melting point and kinematic viscosity and a resin by agglomeration and fusion, a specific solvent is used when cooling the associated liquid after the aging step. The present invention has been completed by finding that the above-mentioned problems can be solved by putting it into the associating liquid and cooling at a specific cooling rate and cooling temperature range.

That is, the present invention includes at least a resin and a release agent, and has a ripening step in the toner production method by aggregation and fusion, and at the end of the ripening step, a solvent is added to the associating liquid to reduce the cooling rate to 0. A step of lowering the liquid temperature by 3 to 35 ° C. at 1 to 30 ° C./min, the SP value of the solvent is 12 to 24, the melting point of the release agent is 60 to 110 ° C., and the kinematic viscosity Is a method for producing a toner of 6 to ²⁰ mm ² / sec.

  According to the present invention, by adding a cooling solvent at the end of the ripening step, the solvent quickly reaches the periphery of the toner particles and promotes cooling of the release agent, so that uniform cooling can be performed at high speed. Further, since the toner is rapidly cooled in a short time, the toner particles are prevented from being deformed. Further, since the solvent enters as a spacer between the toner particles, fusion between the toner particles is suppressed. As a result, the heat resistance of the toner can be improved and the storage stability can be improved.

It is the figure which represented typically the cooling process by one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described.

According to an embodiment of the present invention, the toner production method includes at least a resin and a release agent, and includes a ripening step in the aggregation / fusion process, and a solvent is added to the association liquid at the end of the ripening step. And a step of lowering the liquid temperature by 3 to 35 ° C. at a cooling rate of 0.1 to 30 ° C./min, the SP value of the solvent is 12 to 24, and the melting point of the release agent is 60 to 110 ° C. And a toner production method having a kinematic viscosity of 6 to ²⁰ mm ² / sec.

  Conventionally, when cooling the associated liquid at the end of the aging step, for example, a method of cooling to about 40 ° C. over 1 to 2 hours using a method of cooling by flowing cooling water through a jacket around the reaction kettle Has been used. Alternatively, a method of cooling while transporting by attaching a heat exchanger in the middle of the transportation pipe has been used. When such a heat exchanger is used, it can be cooled at a rate of 10 ° C./min or more, and the associated liquid can be cooled to near room temperature in a few minutes.

  However, in the method of gradually cooling by adding cooling water to the jacket around the reaction kettle, the shape of the release agent changes with the crystallization of the release agent near the melting point of the release agent, and the toner particles There was a problem of oozing out on the surface. In this case, the smoothness of the toner particle surface is lowered, and the degree of deformation of the shape of the manufactured toner particles is increased. In particular, when the crystallization temperature of the release agent used is high, such a problem becomes remarkable.

  On the other hand, when rapidly cooled using a heat exchanger or the like, the change in the shape of the release agent is reduced, but it is difficult to completely prevent the release agent from exuding on the surface of the toner particles. There was a problem that fusion (union) between them would occur.

  The above-described irregular shape of the toner particles and the fusion of the toner particles cause deterioration of heat-resistant storage property and fluidity.

  However, according to the method of the present invention, by introducing a solvent for cooling into the associating liquid, quick and uniform cooling is possible, and the toner particles are deformed because they are rapidly cooled in a short time. Can be suppressed. Further, since the solvent enters between the toner particles as a spacer, fusion between the toner particles can be suppressed. As a result, the heat resistance and storage stability of the toner can be improved.

[Toner Production Method]
Hereinafter, the method for producing the toner of the present invention will be described in detail.

  The method for producing the toner is not particularly limited as long as it is a method for producing toner particles by aggregating and fusing a resin and a release agent, and a known method can be used. For example, a suspension polymerization method, an emulsion association method, a dispersion polymerization method, a dissolution suspension method, a melting method and the like can be exemplified. Among them, the production method by the emulsion association method is particularly suitable in the present invention.

  Hereinafter, typical toner production examples by the emulsion association method will be described.

(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radical polymerizable monomer;
(2) a polymerization step of preparing a dispersion (latex) of resin particles containing a release agent;
(3) an aggregation / fusion process in which resin particles containing a release agent and colorant particles are salted out in an aqueous medium to aggregate / fuse them to obtain associated particles;
(5) A maturing step of aging associated particles with thermal energy to adjust the shape to form toner base particles. (6) Cooling step of cooling an associated liquid (dispersion) containing toner base particles;
(7) A washing step of solid-liquid separating the toner base particles from the cooled association liquid and removing the surfactant and the like from the association particles;
(8) A drying step of drying the washed toner base particles;
(9) An external addition processing step of adding an external additive to the dried toner base particles.

  Hereinafter, each step will be described in detail.

(Dissolution / dispersion process)
This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer solution.

(Polymerization process)
In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to an aqueous medium containing a surfactant, and mechanical energy is applied to form droplets. Next, a polymerization reaction is advanced in the droplets by radicals from a water-soluble radical polymerization initiator, and resin particles are obtained. In addition, resin particles may be added as core particles in the aqueous medium, and several polymerization reactions may be performed.

(Aggregation / fusion process)
Agglomerated particles by adding a salting-out agent composed of an alkali metal salt or an alkaline earth metal salt as an aggregating agent having a critical aggregation concentration or more to an aqueous medium containing resin particles containing a release agent and colorant particles. Form. In the aggregation / fusion process, it is preferable to heat the resin particles to a temperature higher than the glass transition point after the addition of the aggregating agent. In the aggregating step, resin particles containing a release agent and colorant particles can be aggregated together with internal additive particles such as charge control agents and resin particles having different thermal characteristics.

  As a method of agglomeration and fusion, a salting out / fusion method using resin particles obtained by the polymerization step is preferable. In the aggregation / fusion step, the internal additive particles such as the release agent particles and the charge control agent can be aggregated and fused together with the resin particles and the colorant 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 colored particles can be prepared by dispersing a 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, as a surfactant used, the same thing as the above-mentioned surfactant can be mentioned. The colorant (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 / fusion method, which is a preferred agglomeration and fusion 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 particles and colorant particles are present. The agent is added as an aggregating agent having a critical agglomeration concentration or higher, and then salting-out proceeds by heating to a temperature that is higher than the glass transition temperature of the resin particles and higher 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 the 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. Occur. The temperature for adding the salting-out agent needs to be at least the glass transition temperature of the resin 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 particles, the salting-out / fusion of the resin 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 particles, and then the temperature is raised as quickly as possible, the temperature being not lower than the glass transition temperature of the resin particles and not lower than the melting peak temperature (° C.) of the mixture. Heat and stir. 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 obtained by salting out / fusing resin particles and arbitrary particles is obtained.

  In the case of forming particles having a core-shell structure, for example, the core particles obtained by the above method and an aqueous system containing a polymerizable monomer having a polymerizable unsaturated double bond as a surfactant are used. By adding to the medium and emulsion polymerization with heating and stirring, the polymerizable monomer is polymerized and deposited on the surface of the core particles to form a shell layer, thereby forming core-shell structured particles. Can be made.

(Aging process)
Aging is preferably performed by thermal energy (heating).

  Specifically, when the associated particles have reached a desired particle size, for example, a terminator such as sodium chloride is added to stop the particle growth, and thereafter, the liquid containing the associated particles is continuously heated and stirred. In this way, the aggregated particles are prepared by heating temperature, stirring speed, and heating time until the desired circularity is obtained, thereby obtaining toner base particles. The conditions for heating and stirring are not particularly limited. Thus, toner base particles having a desired circularity and a uniform shape can be obtained.

(Cooling process)
This step is a step of cooling the associated liquid containing the toner base particles.

  In the method of the present invention, the association liquid is cooled by adding a solvent to the association liquid at the end of the aging step. In the present specification, the end of the ripening step means that in the ripening step, the degree of circularity of the associated particles is measured at an interval of 10 minutes using a flow type particle image analyzer (FPIA-2000 manufactured by Simex Co., Ltd.). The time when 0.960 ± 0.010 is reached.

  The circularity is a value obtained by the following formula (1), and the average circularity is an average value when 2000 or more particles having a particle diameter of 1 μm or more are measured.

Circularity = (perimeter of equivalent circle) / (perimeter of particle projection image)
= 2π × (projection area of particle / π) ^1/2 / (peripheral length of particle projection image) (1)
Here, the equivalent circle is a circle having the same area as the particle projection image, and the equivalent circle diameter means the diameter of the equivalent circle.

  The circularity can be measured using a flow particle image analyzer (FPIA-2000 manufactured by Simex). At this time, the equivalent circle diameter is defined by the following formula (2).

Equivalent circle diameter = 2 × (projection area of particle / π) ^1/2 (2)
In the present invention, the solvent is a substance added at the end of the association, and may be a solid as long as it dissolves after the addition. Moreover, the mixed solvent containing 2 or more types of solvents may be sufficient. Moreover, you may contain inorganic salt and surfactant in a solvent.

The solvent that can be used in the present invention has an SP value (cal / cm ³ ) ^1/2 of 12 to 24. By introducing a solvent into the association liquid after aging, (a) the solvent reaches the periphery of the toner particles to promote cooling of the release agent, and (b) enters the toner particles as a spacer to prevent fusion. effective. For the above (a), the higher the lipophilicity of the solvent to be added (the lower the SP value), the higher the effect. On the other hand, for the above (b), the lower the lipophilicity of the solvent to be added (the higher the SP value), the higher the effect. Therefore, it is important to use a solvent having an SP value within a predetermined range.

  As for the solvent used by this invention, SP value is 12-24, Preferably it is 12-23, More preferably, it is 12-20, More preferably, it is 13-15. When the SP value of the solvent exceeds 24, the diffusibility is not sufficient, the cooling becomes uneven, and deformation due to a change in the shape of the release agent tends to occur. On the other hand, when the SP value of the solvent is smaller than 12, the repulsive force with the toner is weak and the particles are likely to be fused.

Here, the SP (Solubility parameter) value is a solubility parameter δ at 25 ° C., and is calculated from the molecular cohesive energy density ΔE of the substance and the molecular volume V from δ = (ΔE / V) ^1/2. It is a value inherent to the substance and is a useful measure for predicting the solubility of the substance. The SP value indicates that the polarity is higher as the numerical value is larger, and the polarity is lower as the numerical value is smaller.

  There are various methods such as a viscosity method, a swelling method, a gas chromatographic method, a turbidity method, and the like, and the SP value is measured with a similar value. In addition, it is described in Koda Shinoda, “Solution and Solubility 3rd Edition” (Maruzen Co., Ltd., published in 1991), p. 78, and various documents and the like describe SP values of organic solvents.

In the present invention, the SP value (cal / cm ³ ) ^1/2 is calculated by Project Leader in the molecular calculation package “CAChe” (manufactured by Fujitsu Limited) according to A.I. K. Ghost, et al, J.A. Comput. Chem. 9:80 (1988) is preferable.

As long as the SP value is in the above range, the solvent used in the present invention may be a mixed solvent in which two or more solvents are mixed before being charged. By using a mixed solvent, the SP value can be adjusted to a desired value. The SP value (δ _mix ((cal · cm ³ ) ^1/2 )) of the mixed solvent can be obtained from the following equation.

δ _mix = (x ₁ V ₁ δ ₁ + x ₂ V ₂ δ ₂ +... x _n V _n δ _n ) / (x ₁ V ₁ + x ₂ V ₂ ... + x _n V _n )
Here, x represents the molar fraction of the mixed component, and V represents the molecular volume of the mixed component.

  Moreover, if the SP value is in the above range, the solvent may contain an inorganic salt such as NaCl, or a surfactant such as EMAL E27C manufactured by Kao Corporation.

  Examples of the solvent suitably used in the method of the present invention include methanol (SP value 14.5), ethanol (SP value 12.7), 1-propanol (SP value 12.0), cresol (SP value 13. 3), formic acid (SP value 13.5), acetic acid (SP value 12.6), ethylene glycol (SP value 14.2), phenol (SP value 14.5), water (SP value 23.4), etc. Can be mentioned. Of these, methanol and formic acid are preferable, and methanol is particularly preferable.

  Although it will not restrict | limit especially if it has said SP value as a mixed solvent, It is preferable that it is a mixed solvent containing water. Use of a mixed solvent containing water is preferable in terms of cost. Examples of the mixed solvent containing water include a mixed solvent of alcohols such as methanol and ethanol and water. In particular, a mixed solvent of methanol and water can be preferably used.

  In the method of the present invention, the cooling rate (liquid temperature decreasing rate) is 0.1 to 30 ° C./min, preferably 0.5 to 10 ° C./min, more preferably 1 to 5 ° C./min. It is. If the cooling rate is less than 0.1 ° C./min, or exceeds 30 ° C./min, the toner particles are likely to be deformed.

  Moreover, the fall width | variety of the liquid temperature by addition of a solvent is 3-35 degreeC, Preferably it is 3-30 degreeC, More preferably, it is 5-25 degreeC. When the decrease in the liquid temperature due to the addition of the solvent is less than 3 ° C., the effect of the present invention cannot be sufficiently obtained. Further, when the decrease in the liquid temperature due to the addition of the solvent exceeds 35 ° C., the volume change is likely to occur due to the temperature difference between the inside and outside of the particle, and the degree of deforming becomes large.

  Here, the temperature (liquid temperature) of the associated liquid can be measured by putting a temperature sensor (thermometer (temperature sensor part of CT-1100WR manufactured by ASONE)) into the associated liquid in the reaction vessel.

  In addition, it is preferable to lower the liquid temperature to around room temperature (25 ° C.) after the liquid temperature is lowered by 3 to 35 ° C. by adding the solvent. Here, the means for further reducing the liquid temperature to near room temperature is not particularly limited. For example, cooling can be performed using a heat exchanger or the like.

  In the present invention, it is preferable to add the solvent while controlling the temperature of the solvent, the amount of addition, and the addition rate so that the cooling rate and the reached temperature are achieved.

  The temperature of the solvent to add is 0-40 degreeC, for example, Preferably it is 0-30 degreeC. If it is the said range, an associating liquid can be cooled efficiently. The solvent to be added may be added in a liquid state, or may be added in a solid state at a temperature below its freezing point. For example, it may be added as a solid such as ice and dissolved after the addition to be cooled. By setting it as such a form, it can cool efficiently.

  The amount of the solvent to be added is, for example, 1 to 60% by mass, preferably 3 to 50% by mass, and more preferably 5 to 30% by mass with respect to the association liquid. If it is the said range, the above cooling rates and cooling temperature widths can be achieved and it can cool efficiently.

  In the method of the present invention, steps including an aggregation / fusion step, an aging step and a cooling step are schematically shown in FIG.

(Solid-liquid separation and washing process)
In this solid-liquid separation / washing step, the solid-liquid separation process for solid-liquid separation of the toner base particles from the associated liquid containing the toner base particles cooled to a predetermined temperature in the above-described step, and the solid-liquid separated toner cake (wet A cleaning process is performed to remove deposits such as a surfactant and a salting-out agent from an aggregate of aggregated particles in a state of cake. 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 base 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 water content of the dried toner base is preferably 5% by mass or less, more preferably 2% by mass or less. When the toner base particles that have been dried are aggregated with weak interparticle attractive forces, 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 treatment process)
This step is a step of mixing the dried toner base particles with an external additive as necessary to produce a toner. As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

[toner]
Next, the toner produced by the method of the present invention will be described.

  The toner of the present invention contains at least a resin and a release agent. Preferably, a colorant, a charge control agent, and an external additive are further included.

(resin)
As the polymerizable monomer constituting the resin and forming the resin particles, known monomers can be used. Specifically, it is preferable to use a combination of styrene, acrylic acid or methacrylic acid derivatives, and those having an ionic dissociation group.

  Examples of the polymerizable monomer constituting the resin particles include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p. -Phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene Styrene or styrene derivatives such as pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, methacrylic acid 2-ethylhexyl acid, stearyl methacrylate, meta Methacrylic acid ester derivatives such as lauryl laurate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate, vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and other vinyl ketones, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and other N-vinyl compounds, vinyl naphthalene, vinyl pyridine and other vinyl Examples thereof include acrylic acid or methacrylic acid derivatives such as compounds, 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, and 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, polyfunctionality 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). Nitrile), 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.

  The glass transition temperature of the resin particles is not particularly limited, but is preferably 40 to 70 ° C. The softening point of the resin particles is not particularly limited, but is preferably 80 to 120 ° C. When the softening point is in the above range, the association temperature becomes an appropriate range, and the cooling effect can be obtained more remarkably.

(Release agent)
The mold release agent used in the present invention has a kinematic viscosity of 6 to ²⁰ mm ² / s and a melting point of 60 to 110 ° C. When a release agent having a kinematic viscosity of less than 6 mm ² / s is used, the release agent easily oozes out on the surface of the toner particles during cooling, and the toner particles are likely to be fused. On the other hand, when the kinematic viscosity of the release agent exceeds 20 mm ² / s, the release effect becomes insufficient. Preferably, the kinematic viscosity of the release agent is 7 to 18 mm ² / s, more preferably 8 to 16 mm ² / s. Further, when the melting point of the release agent is less than 60 ° C., the effect of the present invention may not be sufficiently obtained. When the melting point of the release agent exceeds 110 ° C., the toner particles are likely to be deformed. Become. Preferably, the melting point of the release agent is 65 to 105 ° C, more preferably 70 to 100 ° C.

Here, the kinematic viscosity of the release agent refers to a value obtained by measuring with a suspended liquid surface type Ubbelohde viscometer described in JIS K 2283 at 100 ° C. However, when the kinematic viscosity is ² to 10 mm ² / s, a viscometer with viscometer number 1 and viscometer constant 0.01 is used, and the kinematic viscosity is greater than 10 mm ² / s and 30 mm ² / s or less. Was measured using a viscometer with a viscometer number 1C and a viscometer constant of 0.03.

  The melting point of the release agent represents the peak top temperature of the release agent endothermic peak. For example, “DSC-7 differential scanning calorimeter” (manufactured by PerkinElmer), “TAC7 / DX thermal analyzer controller” (PerkinElmer) Etc.). Specifically, 4.00 mg of the release agent is precisely weighed to 2 digits after the decimal point, sealed in an aluminum pan (KITNO.0219-0041), set in a DSC-7 sample holder, and measured at 0 ° C. to 200 ° C. At 2 ° C. under the heat-cool-heat temperature control under the measurement conditions of 10 ° C./min. Analysis was performed based on the data in Heat. An empty aluminum pan was used for the reference measurement.

  Release agents that can be used in the present invention include natural waxes such as carnauba wax, rice wax, and montan wax; polyolefin waxes such as polyethylene wax and polypropylene wax; hydrocarbons such as Fischer-Tropsch wax, paraffin wax, and microcrystalline wax. Examples of such waxes include: ester waxes such as monoester waxes, polyester waxes, and condensed ester waxes thereof; amide waxes; ketone waxes. These waxes can be used alone or in combination of two or more.

  Among the above waxes, Fischer-Tropsch wax, paraffin wax, microcrystalline wax, and monoester wax are particularly preferably used from the viewpoint that a vaporized component is hardly generated and the kinematic viscosity is low.

  Examples of the microcrystalline wax include “HNP-0190”, “HNP-51”, “FT-100”, “HI-MIC-1045”, “HI-MIC-1070”, “HI” manufactured by Nippon Seiki Co., Ltd. -MIC-1080 "," HI-MIC-1090 "," HI-MIC-2045 "," HI-MIC-2065 "," HI-MIC-2095 "and the like. In particular, “HNP-0190” can be preferably used.

  The microcrystalline wax has a low molecular weight with a weight average molecular weight of 600 to 800, preferably a number average molecular weight of 300 to 1,000, and more preferably 400 to 800. Moreover, it is preferable that ratio Mw / Mn of a weight average molecular weight and a number average molecular weight is 1.01-1.20.

  The release agent that can be used in the production of the toner of the present invention may be a mixture of two or more of the above, but when there are two or more peak tops of the release agent endothermic peak of the mixture, It is necessary to use those having both peak tops of 60 to 110 ° C.

  The amount of the release agent added to the toner is not particularly limited, but is preferably 1 to 30% by mass and more preferably 5 to 20% by mass with respect to the resin.

(Coloring agent)
As the colorant, 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 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, and the like.

  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.

  The above colorants can be used alone or in combination of two or more. Further, the amount of the colorant added is, for example, in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

  As the colorant, a surface-modified one can also be used. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

(Charge control agent)
A charge control agent can be added to the toner according to the present invention as necessary. A known compound can be used as the charge control agent.

(External additive)
In the toner of the present invention, in addition to the above-described inorganic fine particles having specific physical properties, a so-called external additive (“external additive”) is also used for the purpose of improving fluidity, chargeability and cleaning properties. Can be used by adding. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  As the inorganic fine particles, it is preferable to use various inorganic oxide particles such as silica, titania and alumina, and these inorganic fine particles are hydrophobized with a silane coupling agent or a titanium coupling agent. Is preferred. As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As the organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer can be used.

  The addition ratio of these external additives is a ratio of 0.1 to 5.0% by mass, preferably 0.5 to 4.0% by mass in the toner. In addition, various external additives may be used in combination.

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 injected into a beaker containing ISOTON II (manufactured by Beckman Coulter, Inc.) in a sample stand with a pipette until the measured concentration is 5 to 10%, and the measuring machine count is set to 30000. To do. 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.

(Developer)
The toner according to 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 μm 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. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle size of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm.

  The particle size of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a 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 coating resin is not particularly limited, and for example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicon resin, an ester resin, a fluorine-containing polymer resin, or the like is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, styrene-acrylic resin, polyester resin, fluorine resin, phenol resin, etc. are used. be able to. Among these, a coat carrier coated with a styrene-acrylic resin is more preferable because it can prevent the external additive from being detached and ensure durability.

[Image forming method]
In particular, the toner of the present invention can be suitably used in an image forming method in which a transfer material on which a toner image is formed is fixed in a contact heating type fixing device.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Example 1>
(Preparation of toner base particles 1)
(Production of resin particles A)
(First stage polymerization)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device was charged with a solution of 7 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 1000 ml of ion-exchanged water and heated to 98 ° C. Then, a solution obtained by dissolving the following monomer solution at 90 ° C. is added, and mixed and dispersed for 1 hour using a mechanical disperser having a circulation path (CLEARMIX manufactured by M Technique Co., Ltd.), and emulsified particles (oil droplets) A dispersion containing was prepared.

(Monomer solution)
Styrene 310g
150 g of n-butyl acrylate
n-Octanethiol 1.8g
115 g of microcrystalline wax (HNP-0190, manufactured by Nippon Seiki Co., Ltd.)
Next, an initiator solution prepared by dissolving 8 g of potassium persulfate in 150 ml of ion-exchanged water is added to this dispersion, and the system is heated and stirred at 82 ° C. for 1 hour to obtain resin particles. It was.

(Second stage polymerization)
A solution prepared by dissolving 12 g of potassium persulfate in 250 ml of ion-exchanged water is added to the solution containing the resin particles prepared as described above.
Styrene 500g
n-Butyl acrylate 100g
Methacrylic acid 35g
n-Octanethiol 15g
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. This is designated as resin particle A. A part of the resin particles A were collected, and Tg measured after washing and drying was 42 ° C.

(Production of resin particles B)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introducing device was charged with 2.3 g of sodium dodecyl sulfate and 3 L of ion-exchanged water, and the internal temperature was adjusted while stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was carried out by stirring to prepare resin particles. This is a dispersion of resin particles B.

Styrene 520g
210g of n-butyl acrylate
Methacrylic acid 68.0g
n-Octanethiol 16.0g
A part of the dispersion of resin particles B was collected, and Tg measured after washing and drying was 48 ° C.

(Preparation of colorant dispersion)
90 g of sodium dodecyl sulfate was dissolved in 1600 ml of ion exchange water with stirring. While stirring this solution, 420 g of carbon black (Regal 330R manufactured by Cabot Corp.) is gradually added, and then dispersed using a stirring device (Cleamix manufactured by M Technique Co., Ltd.), whereby a dispersion of colorant particles is obtained. Was prepared. This is a colorant dispersion. The particle size of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer (ELS-800 manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

(Aggregation / fusion process)
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 430 g of resin particles A in terms of solid content, 1400 g of ion-exchanged water, 120 g of the colorant dispersion produced above, A solution in which 3 g of sodium oxyethylene (2) sodium dodecyl ether sulfate was dissolved in 120 ml of ion-exchanged water was added, the liquid temperature was adjusted to 30 ° C., and then the pH was adjusted to 10 by adding a 5N aqueous sodium hydroxide solution. Next, an aqueous solution obtained by dissolving 35 g of magnesium chloride in 35 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring (150 rpm). After holding for 3 minutes, the temperature was raised, and the system was heated to 86 ° C. over 60 minutes at 250 rpm, and the particle growth reaction was continued while stirring at 150 rpm while maintaining 86 ° C. In this state, the particle size of the associated particles was measured using a Coulter Multisizer (Coulter Multisizer III, manufactured by Beckman Coulter, Inc.). When the median diameter on the volume basis became 3.1 μm, the dispersion of the resin particles B 200 g of liquid was added, and the particle growth reaction was continued. When the desired particle size (6.5 μm) was reached, an aqueous solution in which 150 g of sodium chloride was dissolved in 600 ml of ion-exchanged water was added to stop particle growth.

(Aging process)
Furthermore, by heating and stirring (250 rpm) at a liquid temperature of 81 ° C. as an aging step, the average circularity is 0.960 as measured by a flow type particle image analyzer (FPIA-2000 manufactured by Simex). The fusion proceeded.

(Cooling process)
When the average circularity reached 0.960, 380 g of methanol having a liquid temperature of 20 ° C. was added dropwise to 4000 g of the associated liquid while adjusting stirring so that the liquid temperature was lowered by 5 ° C. in 1 minute.

  The liquid temperature dropped from 81 ° C. before dropping methanol to 75 ° C. after dropping. In 1 minute from the end of the dropwise addition, the heat-reserving bath outside the reaction kettle was replaced with water having a water temperature of 20 ° C., and cooled to 40 ° C. or lower. The arrival time up to 40 ° C. was 10 minutes. The average circularity measured was 0.957. Thereafter, hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing / drying process)
The particles produced in the above aggregation / fusion process were solid-liquid separated with a basket type centrifuge (MARK III model number 60 × 40 manufactured by Matsumoto Machine Sales Co., Ltd.) to form a wet cake of toner base particles. The wet cake was washed with ion exchange water at 45 ° C. until the electrical conductivity of the filtrate reached 5 μS / cm using the basket-type centrifuge, and then transferred to a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.). The toner base particles 1 were prepared by drying until the water content was 0.5% by mass. The obtained toner base particles 1 had a Tg of 43 ° C.

(Production of toner particles)
To the toner base particles 1 obtained above, 1% by mass of hydrophobic silica (number average primary particle diameter 12 nm) with respect to the toner base particles 1 and hydrophobic titania (number average primary particle diameter 20 nm) 0 The toner particles were prepared by adding 3 mass% and mixing with a Henschel mixer.

<Examples 2 to 5>
Toner particles were prepared in the same manner as in Example 1 except that the cooling rate and the temperature drop after the aging step were changed as shown in Table 1 below.

<Examples 6-14, Comparative Examples 1-4, 6-8>
Toner particles were prepared in the same procedure as in Example 1 except that the solvent used for cooling after the aging step, the cooling rate, and the release agent were changed as shown in Table 1 below. The mixing ratio of the mixed solvent represents a volume ratio.

<Comparative Example 5>
Instead of the cooling method of Example 1, the associated liquid was transported (75 L / min) through a pipe having a plate-type heat exchange system (electric heating area: 67 m ² , material: SUS316) in the middle from the reaction kettle to the storage tank. Toner particles were prepared in the same procedure as in Example 1 except that the temperature was reduced to 20 ° C. at a cooling rate of ° C./min.

<SEM observation>
The toner produced in each example and comparative example was observed with a scanning electron microscope. An image (50 μm × 50 μm) was visually observed, and the total number of particles and the number of particles in which two or more toner particles were united were counted. In addition, among the toner particles, the number of particles (wax crystal exposed particles) in which the release agent (wax) crystals are exposed on the surface with a length of 1/5 or more of the particle diameter of the particles was counted. The ratio of particles in which two or more toner particles are united and the ratio of wax crystal exposed particles are defined as follows.

Ratio of particles in which two or more toner particles are combined (%) = (number of particles in which two or more toner particles are combined / total number of particles) × 100
Ratio of wax crystal exposed particles (%) = (number of wax crystal exposed particles / total number of particles) × 100
<Variation>
When cooled at the end of the association, the release agent crystallizes and precipitates on the toner surface at that time, thereby reducing the smoothness of the toner surface. As a result, when compared at the end of the ripening step and at the end of cooling, the value of circularity represented by the following formula decreases. The difference in average circularity at the end of the aging process and at the end of cooling is defined as the degree of deformation. In the present invention, when the average circularity value decreases by 0.005 or more at the end of cooling, it is determined that the profile has been deformed. Deformation can cause deterioration in heat-resistant storage stability and fluidity.

<Circularity>
The circularity of the toner was measured using FPIA-2100 manufactured by Simex. Specifically, after the toner is blended with an aqueous solution containing a surfactant and dispersed by ultrasonic dispersion for 1 minute, the number of detected HPFs in the measurement condition HPF (high magnification imaging) mode using FPIA-2100. Measurement is performed at an appropriate concentration of 3000 to 10,000. Within this range, the same reproducible measurement value can be obtained. The circularity defined by the following formula was measured.

Circularity = (perimeter of a circle having the same projection area as the particle projection image) / (perimeter of the particle projection image)
The average circularity is a value calculated by adding the circularity of each particle and dividing by the total number of particles.

<Heat resistant storage stability of toner>
2 g of each toner prepared above was taken in a sample tube, shaken 500 times with a tapping denser, and allowed to stand in an environment of 55 ° C. and 35% RH for 2 hours. Next, it is put into a sieve of 48 μm mesh, sieved under a constant vibration condition, the ratio (mass%) of the remaining toner amount on the mesh is measured, this is defined as the toner aggregation rate, and the toner is stored according to the criteria described below. The stability was evaluated.

A: Toner aggregation rate of less than 15% by mass (toner storage stability is very good, no problem during image formation)
○: Toner aggregation rate of 15 to 45% by mass (good toner storage stability, no problem during image formation)
Δ: The toner aggregation rate exceeds 45% by mass and is 60% by mass or less (the storage stability of the toner is slightly poor, and there are some problems during image formation, but the acceptable range of use)
X: The toner aggregation rate exceeds 60% by mass (cannot be used because the storage stability of the toner is poor and a problem occurs during image formation).

  The obtained results are shown in Table 1 below.

  From the results shown in Table 1, the toners produced in Examples 1 to 14 have a low ratio of particles in which two or more particles are united or wax crystal exposed particles, and the circularity is maintained. I understand that. And it was confirmed that high storage stability is obtained.

  In particular, compared to the case where the associated liquid was cooled using a heat exchanger as in Comparative Example 5, in Examples 1 to 14, the proportion of particles in which two or more toner particles were united was greatly reduced. Has been. This is considered to be because the solvent became a spacer between the particles and the fusion of the particles was suppressed by adding the solvent.

  When the cooling rate or the cooling temperature width is smaller than the range of the present invention as in Comparative Examples 1 to 4, the effect of the present invention cannot be sufficiently obtained, and the release agent is also larger than the range of the present invention. Oozing out cannot be sufficiently suppressed, and the degree of deforming becomes large.

  Further, when the kinematic viscosity of the release agent is low as in Comparative Example 6, the release agent tends to ooze out and toner particles are likely to be fused. It has been found that when the melting point of the release agent is low as in Comparative Example 7, the profile is likely to be deformed. Further, when the SP value of the solvent is smaller than 12 as in Comparative Example 8, the particles are fused. Prone to occur.

Claims (4)

In the method for producing toner by aggregation / fusion, including at least a resin and a release agent,
Has an aging process,
At the end of the aging step, a step of adding a solvent into the association liquid and lowering the liquid temperature by 3 to 35 ° C. at a cooling rate of 0.1 to 30 ° C./min,
The SP value of the solvent is 12-24,
A method for producing a toner, wherein the releasing agent has a melting point of 60 to 110 ° C. and a kinematic viscosity of 6 to ²⁰ mm ² / sec.   The temperature of the solvent to be added is 0-40 degreeC, and the ratio added is 1-60 mass% with respect to the said association liquid, The manufacturing method of Claim 1.   The manufacturing method according to claim 1, wherein the solvent is a mixed solvent containing water.   The said solvent is a manufacturing method of any one of Claims 1-3 injected | thrown-in as a solid in the state below a freezing point.