JP3456372B2 - Electrophotographic toner and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic charge image used in electrophotography and a method for producing the same.

[0002]

2. Description of the Related Art A kneading and pulverizing method is known as a method for producing a toner for developing an electrostatic image which has been conventionally used in electrophotography. The kneading and pulverizing method, which is a method for obtaining the toner of No. 3, was generally used. To the toner obtained by this kneading and pulverization method, a wax such as a low molecular weight polyolefin is added as a release agent to the toner in order to prevent the so-called offset in which the toner remains on the fixing roller. The release agent such as the low molecular weight wax is effective for preventing offset, but filming that adheres to the photoconductor or the carrier occurs, and there is a problem in cleaning property and stability over time. In order to prevent this filming, for example, JP-A-62-143061 and JP-A-3-14864.
No. 9 proposes a method of reducing the particle size of a release agent such as wax. Further, as a color toner, polyester may be dispersed with a polyolefin wax by kneading (JP-A-3-107869), or OHP.
A toner prepared by a suspension polymerization method containing a polyalkylene having a low crystallinity for improving the permeability of the toner (Japanese Patent Laid-Open No. 5-197191) is known. On the other hand, after dispersing the release agent in the shape of a rod or needle in the resin composition, the wax domain is sheared to improve the dispersibility of the wax (JP-A-6-289645) and to prevent filming. In order to prevent wax separation during grinding, the wax shape may be spindle-shaped (Japanese Patent Laid-Open No. 7-161).
144, JP-A-7-161145), and spherical wax particles having a small particle size are dispersed (JP-A-8-328).
293).

However, the toner prepared by the kneading and pulverization method with the above wax blended is unevenly distributed on the surface of the obtained particles, so that (1) the toner's chargeability, fluidity, life and the like are deteriorated. , (2) Poor dispersibility of wax having a low softening point, (3) There is a limit to the resin that can be pulverized,
For example, there is a problem in that sharp melt low molecular weight polyester for color toner cannot be used. On the other hand, as a method for producing toner particles for improving the above-mentioned problems other than the kneading and pulverizing method, a method of granulating an oil phase component obtained by dissolving a polyester resin in an organic solvent in an aqueous medium containing an inorganic dispersant is known. (JP-A-7-152202, JP-A-7-168395, JP-A-7-168396). According to these production methods, although the wax is less likely to be exposed on the surface, the dispersion unit of the wax dispersed in the toner in the granulation step becomes large, the light transmittance of the particles decreases, and when used as a color toner, There were drawbacks such as low color development and poor OHP transparency. Further, when the amount of wax exposed on the surface is small, the effect of preventing the offset property by the wax is weak. For example, a wax which is unevenly distributed in the central portion of the toner particles does not contribute much to the offset resistance and a larger amount of wax is used. Needed to be added. On the other hand, as a method for dispersing a release agent such as wax,
Although there are stirring, ultrasonic treatment, and the like, if these are used, fine particle formation is insufficient and sufficient dispersion cannot be obtained. Further, although it is possible to reduce the particle size by applying strong shearing, impact, cavitation, etc. with a pressure homogenizer, etc., the particles cannot be spheroidized, and the temperature further rises and the release agent is released. Re-aggregation occurs, and a sufficient dispersion of the release agent is not always obtained. Especially, for a release agent having a low melting point,
There is a drawback that re-aggregation proceeds further and dispersion of the release agent becomes worse.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a toner in which spherical fine particles of a release agent are dispersed in the toner, which has offset resistance, chargeability, and fluidity. Another object of the present invention is to provide an electrophotographic toner having excellent stability, good color development, and OHP transparency, and a method for producing the same.

[0005]

The electrophotographic toner of the present invention comprises an oil phase component prepared by dissolving or dispersing at least a binder resin, a colorant, and a release agent in an organic solvent capable of dissolving the binder resin. In a toner for electrophotography produced by a production method including a step of preparing a release agent and a step of dispersing the oil phase component in an aqueous medium and granulating the release agent, the release agent is preliminarily dissolved in an organic solvent and then deposited. A toner for electrophotography, which is a dispersion liquid of a release agent obtained by crushing and / or dispersing with a medium after being applied or after being previously suspended in an organic solvent.

In the present invention, one method for dispersing the spherical fine particles of the release agent in the toner is to dissolve at least the binder resin, the colorant, and the release agent in an organic solvent that dissolves the binder resin. In the method for producing an electrophotographic toner, which comprises a step of dispersing to disperse the oil phase component to prepare an oil phase component, and a step of dispersing the oil phase component in an aqueous medium to granulate, in an organic solvent in which the binder resin is dissolved. As a release agent to be dispersed in, a dispersion of the release agent obtained by preliminarily dissolving it in an organic solvent and then precipitating it or suspending it in an organic solvent in advance and crushing and / or dispersing it with a medium is obtained. The method used may be mentioned. The toner of the present invention preferably satisfies the condition of the shape factor represented by the following formula (1).

## EQU4 ## f ≦ 1.25 (1) (where, f = a / b, a is the average length of the major axis of the release agent particles, and b is the short axis of the release agent particles. Further, in the present invention, the spherical fine particles of the release agent dispersed in the toner have an average particle diameter in the range of 0.01 to 1.5 μm, and the shape is the shape factor ( f), f ≦ 1.2
It is desirable that the release agent spherical fine particles satisfy the condition 5). As one of the methods for producing such a toner, a step of dissolving or dispersing at least a binder resin, a colorant, and a release agent in an organic solvent capable of dissolving the binder resin to prepare an oil phase component And a method for producing an electrophotographic toner, which comprises a step of dispersing the oil phase component in an aqueous medium and granulating, and an organic solvent is previously used as a release agent to be dispersed in an organic solvent in which the binder resin is dissolved. Dissolves in and precipitates,
Alternatively, a suspension of a release agent obtained by pulverizing and / or dispersing with a media after being suspended in an organic solvent in advance is used, and at the time of pulverizing and / or dispersing with a medium, at least the release agent is used. And the temperature of the dispersion liquid containing the organic solvent is set to 40 ° C. or lower. When the temperature of the dispersion liquid exceeds 40 ° C., the spherical and finely divided release agent reaggregates, and it becomes impossible to obtain desired release agent spherical fine particles.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The toner of the present invention contains at least a binder resin, a colorant and a release agent. Examples of the binder resin used in the present invention include styrenes such as styrene, parachlorostyrene, and α-methylstyrene, methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate. , Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate,
Esters having vinyl group such as lauryl methacrylate and 2-ethylhexyl methacrylate, vinyl nitriles such as acrylonitrile and methacrylonitrile, vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl Vinyl ketones such as isopropenyl ketone,
Polymers such as monomers of polyolefins such as ethylene, propylene and butadiene, copolymers obtained by combining two or more kinds thereof, or a mixture thereof, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin Examples thereof include non-vinyl condensation resins such as polyether resins, mixtures of these with the above vinyl resins, and graft polymers obtained when a vinyl monomer is polymerized in the coexistence of these.

The polyester resin is obtained by polycondensation of an alcohol component and a carboxylic acid component, and each component includes the following. As the alcohol component, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol,
Xylylene glycol, dipropylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide, bisphenol A propylene oxide, sorbitol,
Dihydric or higher alcohols such as glycerin and alcohol derivatives can be mentioned. As the carboxylic acid component, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, trimellitic acid, pyromellitic acid, cyclopentanedicarboxylic acid, succinic anhydride, trimellitic anhydride, anhydrous Examples thereof include dicarboxylic or higher carboxylic acids such as maleic acid and dodecenyl succinic anhydride, carboxylic acid derivatives, and anhydrides thereof. The alcohol component and the carboxylic acid component may each be a combination of two or more kinds.

As a solvent which dissolves these binder resins to form an oil phase component, a usual organic solvent which dissolves each resin is used. For example, hydrocarbons such as toluene, xylene and hexane, halogenated hydrocarbons such as methylene chloride, chloroform and dichloroethane, alcohols such as methanol and ethanol, ethers such as tetrahydrofuran, esters such as methyl acetate, ethyl acetate and butyl acetate. , Ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and these may be used alone or as a plurality of mixed solvents. The mixing ratio of these solvents and the resin is resin / solvent = 5/95 to 50/50.
Is desirable.

As the releasing agent in the present invention, paraffin wax, oxidized paraffin wax, petroleum wax such as microcrystalline wax, mineral wax such as montan wax, animal and plant wax such as carnauba wax, polyolefin wax, oxidized polyolefin wax, Fischer-Tropsch. Examples thereof include synthetic wax such as wax, ester wax, ether wax and the like. The melting point of the releasing agent is preferably 120 ° C. or lower, and lower in terms of offset resistance of the toner. Further, from the viewpoints of handleability, ease of production, and storability, the melting point is preferably 40 to 120 ° C, more preferably 50 to 100 ° C. However,
It can also be applied to a wax that is liquid at room temperature, that is, a release agent having a melting point of less than 40 ° C.

The toner of the present invention is characterized in that spherical fine particles of a release agent are dispersed therein.
One of the production methods is to disperse the release agent in a solvent in a small dispersion unit and in a spherical shape before adjusting the oil phase component by dispersing the release agent together with the resin and the colorant in the organic solvent. Is characterized by. By preliminarily dispersing the releasing agent in a small dispersion unit and in a spherical shape, the particles of the releasing agent dispersed in the obtained toner particles can be made into a small dispersion unit and in a spherical shape. Both the offset property and the fixing property can be satisfied. The release agent particles in the release agent dispersion have an average particle size of 0.01 to 1.5.
μm range, and the shape factor (f), f ≦
The spherical fine particles satisfying the condition of 1.25 are preferable. In particular, it is desirable that the average particle size is in the range of 0.1 to 0.5 μm. If the average particle size of the release agent is less than 0.01 μm, the effect of improving the offset resistance decreases, and
When it exceeds, the transparency in OHP is lowered and filming easily occurs, which is not preferable. The average particle size of the release agent particles is measured by a laser diffraction / scattering type particle size distribution measuring device (for example, LA-700 or LA-910 manufactured by Horiba Ltd.).
Etc. can be used for measurement.

As a method for producing a spherical fine particle dispersion of a release agent, the release agent is dissolved in an organic solvent in advance and precipitated, or suspended in an organic solvent in advance, that is, the release agent. A method of pulverizing and / or dispersing the release agent with a medium after producing the crude dispersion liquid of 1. In order to further reduce the average particle size of the dispersion release agent particles, the temperature of the dispersion liquid containing at least the release agent and the organic solvent should be 40 ° C. or lower when the release agent is pulverized and / or dispersed by the media. There is a method of doing. As the organic solvent used in the method for producing the release agent dispersion, the same organic solvent as the organic solvent capable of dissolving the binder resin may be used alone, or a plurality of types may be mixed and used. The organic solvent used for forming the spherical fine particles of the release agent and the organic solvent constituting the oil phase component do not necessarily have to be the same. However, if the same one is used, it is not necessary to consider the compatibility between the solvents, it is easy to control the blending amount of the organic solvent that constitutes the oil phase component, and the oil dispersion remains stable in the release agent. It has the advantage that the phase components can be adjusted.

The amount of the organic solvent used for finely dispersing the release agent is preferably about 1 to 20 parts by weight of the organic solvent with respect to 1 part by weight of the release agent. If the amount of the organic solvent is small, uniform fine dispersion cannot be obtained, and if it is too large, the dispersion density of the release agent is lowered, and when blended in the oil phase component, the amount of the solvent is excessive and productivity is lowered.

As a method for obtaining a crude dispersion of the release agent, there may be mentioned a method of dissolving the release agent in an organic solvent and then depositing it, or a method of suspending the release agent in the organic solvent. As the former method, a method of adding a release agent to an organic solvent, stirring or adding, stirring, heating, etc. to dissolve the release agent in the organic solvent, and then cooling to precipitate the release agent is adopted. Further, as the latter method, a method of suspending a particulate release agent in an organic solvent or the like is adopted. Furthermore, when cooling and precipitating, ultrasonic treatment may be used together.

The crude dispersion of the release agent thus obtained is pulverized and / or dispersed by using a medium to form a release agent of spherical fine particles. Specific methods using media include so-called media mills and media agitation mills such as ball mills, sand mills, attritors, co-ball mills, DCP mills and fine mills. The release agent particles are smaller particles, that is, the average particle diameter is 0.01 to 1.5.
In order to obtain spherical particles with a particle size in the range of μm, it is necessary to set the dispersion liquid temperature in the crushing and / or dispersing region to 40 ° C. or lower when crushing and / or dispersing the release agent with the media. However, for this purpose, it is necessary to effectively cool the heat generated by the dispersion treatment in the crushing and / or dispersion region, and a device having a mechanism capable of effectively cooling the dispersion liquid, for example, a sand mill, an attritor, Coball mill,
Grinding and / or dispersion is performed using a DCP mill, a fine mill, or the like. Further, in order to form a release agent having a smaller particle size and a more spherical shape, it is necessary to control the temperature of the dispersion liquid in the crushing and / or dispersion region to 20 ° C. or lower, optimally 10 ° C. or lower. . As an apparatus having a mechanism capable of efficiently cooling the dispersion liquid, for example, a coball mill, a DC
P mills, fine mills and the like are preferable, and more preferable are DCP mills capable of cooling the rotor / stator part,
Fine mills are used.

In the present invention, the shape of the medium used when preparing the dispersion liquid of the spherical fine particles of the release agent may be cylindrical, spherical or the like, but the efficiency of crushing and dispersion, and the adaptability to a dispersion device. Considering the property, the spherical shape is preferable. The size of the spherical medium is preferably 0.1 to 5 mm in diameter, but 0.1 to 2 mm in diameter is preferable in order to effectively make the shape of the release agent spherical and fine particles. When the release agent is pulverized and / or dispersed in a medium after being dissolved or suspended in the organic solvent, the dispersion liquid temperature in the pulverization and / or dispersion region is preferably 40 ° C. or lower, preferably 20 ° C
The following is optimally 10 ° C. or lower. When the temperature of the dispersion liquid exceeds 40 ° C., the spherical and finely divided release agent reaggregates, and it becomes impossible to obtain desired release agent spherical fine particles.

As the colorant of the present invention, known organic or inorganic pigments or dyes and oil-soluble dyes can be used. For example, C.I. I. Pigment Red 48: 1, C.I.
I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Yellow 17, C.I.
I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I. I. Pigment Blue 15: 1, C.I.
I. Pigment Blue 15: 3, Lamp Black (C.I.
I. No. 77266), Rose Bengal (C.I.N.
o. 45432), carbon black, acetylene black, aniline black, nigrosine dye (CIN
o. 50415B), metal complex salt dyes, derivatives of metal complex salt dyes, and mixtures thereof. These colorants are added in an amount of about 1 to 50 parts by weight, preferably 2 to 20 parts by weight, based on 100 parts by weight of the resin.

The oil phase component in the production method of the present invention is prepared by dissolving or dispersing a binder resin, a colorant, a release agent, etc. in an organic solvent capable of dissolving the binder resin. As other additives that can be added to the phase component,
A toner fluidity adjusting agent, a charge control agent and the like can be mentioned, and these can be optionally added within a range not impairing the effects of the present invention. As additives for controlling the fluidity of the toner, silica, aluminum oxide, magnetite and various ferrites, cupric oxide, nickel oxide,
Examples thereof include various metal oxides such as zinc oxide, zirconium oxide, titanium oxide and magnesium oxide, and appropriate mixtures thereof. The addition amount of these is preferably 5% by weight or less with respect to the binder resin, and more preferably 0.05 to 3% by weight.

The charge control agent that can be used in the present invention may be one that has been used in conventional developers, but is used in powder toners for xerography, such as a metal salt of benzoic acid and a metal of salicylic acid. Salts, metal salts of alkylsalicylic acid, metal salts of catechol, metal-containing bisazo dyes, tetraphenylborate derivatives, quaternary ammonium salts, compounds selected from the group consisting of alkylpyridinium salts, and combinations thereof as appropriate. It can be preferably used. The amount of these charge control agents added to the toner solids is generally in the range of 10% by weight or less, preferably 0.01 to 5% by weight.

As described above, the oil phase component obtained by dissolving or dispersing the toner composition containing the binder resin, the colorant, the release agent and the like in the organic solvent is then mixed and stirred in an aqueous medium. Granulation is performed to form toner particles. The aqueous medium used here is mainly water, but a water-soluble solvent can be mixed and used. The amount of the aqueous medium used with respect to the oil phase component is: oil phase / aqueous medium = 60/40
It is preferably in the range of 10/90, and more preferably in the range of 50/50 to 25/75 from the viewpoint of dispersibility. When dispersing the oil phase component in the aqueous medium, a dispersant may be added. If you add a dispersant,
It has an effect of narrowing the particle size distribution of the obtained toner particles.
Examples of the dispersant include tricalcium phosphate, hydroxyapatite, calcium carbonate, titanium oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, silica, cellulose, starch, polyvinyl alcohol, polyacrylic acid and the like. The amount of dispersant is 10
It is preferably 20 parts by weight or less with respect to 0 parts by weight. As a method of granulation, when mixing and stirring the oil phase component in an aqueous medium, it is preferable to add shear, a rotor-stator type disperser, for example, a known stirrer such as a colloid mill or a homogenizer, a cooking mixer, A mixer or a disperser can be used. Granulation is 0 ~ 70 ℃
It is preferable to carry out for 1 minute to 1 hour while applying a shearing force in the temperature range.

By removing the solvent after the granulation and further removing the remaining dispersant and the like, it is possible to obtain toner particles having a uniform particle size in which the spherical fine particles of the release agent are finely dispersed. . The releasing agent average dispersion unit of the obtained toner particles and the shape of the releasing agent are preferably such that the particle size is in the range of 0.01 to 1.5 μm as described above, and
The shape is spherical fine particles having the above-mentioned shape factor (f), f ≦ 1.25. The dispersion state of the release agent is obtained by taking a cross section of the toner particles in an electron microscope (TEM) photograph, and showing the dispersion unit of the release agent. It can be determined by measuring the diameter of the cross section.

Since the electrophotographic toner obtained by the manufacturing method of the present invention is granulated in an aqueous medium, the shape can be easily controlled and spherical toner particles can be easily obtained. Further, since the release agent is finely dispersed and contained in the particles, the transferability and the fixability of the toner to the support such as paper are good, and the offset is not seen even without the oil of the fixing roll, and It has excellent characteristics of high permeability.

In the toner particles for electrophotography of the present invention, since the oil phase component is granulated in the aqueous medium, the releasing agent is separated due to the difference in affinity between the releasing agent and the oil phase component and the releasing agent and the aqueous medium. The agent is hard to be exposed on the surface, and the release agent particles dispersed in the toner are spherical, preferably the shape factor (f), f.
By making the spherical fine particles of ≦ 1.25, the release agent is hardly exposed on the surface of the toner particles, the toner fluidity is improved, and the charging property is improved. Therefore, even if a releasing agent having a low melting point is used, the exposure to the surface is small, and there is no problem in fluidity and storability. Further, by containing a release agent in the toner, it is possible to fix without oil, the toner has excellent color developability and OHP transparency, and the toner has good fluidity and storability, and good chargeability. Further, in the electrophotographic toner of the present invention, the release agent to be dispersed in the organic solvent is dissolved in the organic solvent in advance and precipitated, or after suspended in the organic solvent in advance, the media is used. A dispersion liquid of a release agent obtained by pulverizing and / or dispersing a release agent is used, and when pulverizing and / or dispersing with a medium, the temperature of the dispersion liquid containing at least the release agent and the organic solvent is controlled. In the electrophotographic toner obtained by the production method including the step of maintaining the temperature at 40 ° C. or lower, the toner release agent has a dispersion unit in the range of 0.01 to 1.5 μm on average, and the shape is the shape factor described above. Dispersed as spherical fine particles satisfying (f) and f ≦ 1.25. As a result, in addition to the characteristics of the toner described above, this toner can prevent the light scattering due to the release agent, and thus the color development and OHP
Has the effect of excellent transparency. Further, in this toner, melting of the release agent occurs quickly, so that the release agent performance can be efficiently expressed.

The diameter of the toner particles in the present invention is not particularly limited, but when the toner particle diameter to be obtained is made smaller, the particle size of the release agent particles dispersed therein is 1. It is desirable to eliminate release agent particles with large disperse units above 5 μm. By doing so, the effect of spheroidizing the particles of the release agent becomes large, and excellent characteristics are obtained even in the case of small-sized toner particles, for example, small-sized toner particles of 6 μm or less, for the purpose of improving image quality. Obtainable.

Further, the electrophotographic toner of the present invention is a developer used in an image forming method including a step of forming a latent image on an image carrier and a step of developing the latent image with a developer. Can be applied as

[0026]

【Example】

(Example 1) Paraffin wax (trade name: HNP (high-purity refined paraffin wax) manufactured by Nippon Seiro, melting point 89
℃) 30 parts by weight to ethyl acetate 250 parts by weight,
The crude wax dispersion at 25 ° C, which was obtained by heating and melting at 0 ° C and precipitation by cooling, was used together with zirconia media having a diameter of 0.5 mm to prepare DCP mill SF-12 (manufactured by Eirich Japan).
And was pulverized and / or dispersed to a unit integrated power of 0.50 kWh / kg to obtain an ethyl acetate dispersion of wax. At this time, the temperature of the wax dispersion liquid in the pulverizing and / or dispersing area was 15 ° C. The average particle size of the wax is measured by a laser diffraction / scattering type particle size distribution measuring device LA-91.
0 (manufactured by Horiba Ltd.) was 0.90 μm (the particle size measured by LA-910 is 50% frequency particle size-median size-on a volume basis). The shape of the wax in the wax dispersion was observed by a scanning electron microscope (SEM). As a result, the average length (a) of the major axes of the wax was 0.95 μm, and the average length (b) of the minor axes of the wax was 0.
It was 80 μm and the shape factor (f = a / b) was 1.19. The measurement was performed by averaging 20 wax particles from the SEM photograph.

100 parts by weight of a polyester resin (weight average molecular weight: 15000, Tg 64 ° C., Tm 102 ° C.) consisting of a bisphenol A propylene oxide adduct, a bisphenol A ethylene oxide adduct, and a succinic acid derivative, C.I. I. Pigment Blue 15: 3 4 parts by weight,
After dispersing 80 parts by weight of ethyl acetate in a ball mill for 10 hours,
An oil phase component was prepared by adding 36 parts by weight of an ethyl acetate dispersion of wax and stirring well until the mixture became uniform. 60 parts by weight of calcium carbonate and 40 parts by weight of water were dispersed in a ball mill for 10 hours to obtain a calcium carbonate dispersion liquid. 7 parts by weight of this calcium carbonate dispersion and 100 parts by weight of a 2% by weight aqueous solution of serogen BS-H (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were put into a cooking mixer MX-915C (manufactured by Matsushita Electric Industrial Co., Ltd.) and mixed for 5 minutes to form an aqueous phase. Make a liquid. To this water phase liquid, 100 parts by weight of the oil phase liquid was added, mixed with a cooking mixer for 6 minutes, and then 40
C. Heat in a water bath to remove organic solvent. 6N hydrochloric acid 1
After removing calcium carbonate by adding 00 parts by weight, washing with water
It was dried and classified to obtain a solid toner having an average particle size of 7.1 μm. The SEM photograph shows that the shape is almost spherical. In order to confirm the wax shape in the toner, the cross section of the toner particles is taken by an electron microscope (TEM) photograph, and the diameter of the cross section of the dispersion unit of the wax is measured, so that the average length (a) of the long axis of the wax is 1 20 μm, the average length (b) of the minor axis of the wax is 0.98 μm, and the shape factor (f =
a / b) was 1.22. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was dispersed inside the toner and was not visible on the surface of the toner particles.

1 part by weight of silica R972 (manufactured by Nippon Aerosil) was mixed with 100 parts by weight of the toner in a sample mill for 1 minute. The silica externally added toner thus obtained was A-colored.
Using 935 (manufactured by Fuji Xerox), image formation was evaluated without fixing fuser oil, and the results are shown in Table 1. The evaluation method is as follows. Regarding the image quality, the color tone, the image density, the presence or absence of fog, and the fixability with paper and OHP were visually observed at the initial stage and after copying 1000 sheets. The offset was visually confirmed whether toner adhered to the fixing roll at the initial stage or after copying 1000 sheets. The light transmittance of the OHP was measured by fixing the solid image on the OHP and then measuring the light transmittance at a wavelength at which the colorant was not absorbed. The wax diameter in the toner was determined from the average value of 10 horizontal diameters randomly selected from the TEM photograph of the toner cross section. Storability of toner is 50 ° C
The presence or absence of aggregation after standing for 3 hours was examined. The transfer property was visually checked for the presence or absence of toner on the surface of the photoreceptor immediately after transfer to paper.

(Example 2) The temperature of the wax dispersion liquid during the treatment with DCP mill SF-12 (manufactured by Eirich Japan) was 5.
An ethyl acetate dispersion of wax was obtained in the same manner as in Example 1 except that the temperature was 0 ° C. The average particle size of wax is
It was 0.50 μm when measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba Ltd.).
When the wax shape in the wax dispersion was observed with a scanning electron microscope (SEM) in the same manner as in Example 1, the average length of the major axis of the wax (a) was 0.55 μm, and the average length of the minor axis of the wax was 0.55 μm. (B) was 0.48 μm, and the shape factor (f = a / b) was 1.15. Bisphenol A
Polyester resin consisting of propylene oxide adduct, bisphenol A ethylene oxide adduct, succinic acid derivative (weight average molecular weight: 15000, Tg 64 ° C,
Tm 102 ° C.) 100 parts by weight, C.I. I. Pigment Red 57 (3 parts by weight) and ethyl acetate (100 parts by weight) were dispersed in a sand mill for 5 hours, 36 parts by weight of an ethyl acetate dispersion liquid of wax was added, and the mixture was stirred well until a uniform solution was prepared. 60 parts by weight of calcium carbonate and 40 parts by weight of water were dispersed in a ball mill for 10 hours to obtain a calcium carbonate dispersion liquid. 6 parts by weight of this calcium carbonate dispersion and serogen BS
100 parts by weight of a 2% by weight aqueous solution of -H (Daiichi Kogyo Seiyaku Co., Ltd.) was put into a cooking mixer MX-915C (Matsushita Electric Industrial Co., Ltd.) and mixed for 5 minutes to prepare an aqueous phase liquid. 50 parts by weight of the oil phase liquid was added to this water phase liquid, and the mixture was mixed with a cooking mixer.
After mixing for a minute, the mixture was heated in a 40 ° C water bath to remove the organic solvent. After adding 100 parts by weight of 6N hydrochloric acid to remove the calcium carbonate, washing with water, drying and classification were carried out to obtain an average particle diameter of 6.1 μm.
Of solid toner was obtained. The SEM photograph showed that the shape was almost spherical. To confirm the shape of the wax in the toner, the TEM photograph was observed in the same manner as in Example 1. As a result, the average major axis (a) of the wax was 0.68 μm.
The short axis average length (b) of the wax was 0.57 μm, and the shape factor (f = a / b) was 1.19. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was dispersed inside the toner and was not visible on the surface of the toner particles. A silica external additive toner obtained by mixing 1 part by weight of silica R972 (manufactured by Nippon Aerosil) with 100 parts by weight of a toner in a sample mill for 1 minute was subjected to image evaluation without using a fixing fuser oil using A-color 935 (manufactured by Fuji Xerox). The results obtained are shown in Table 1.

Example 3 250 parts by weight of ethyl acetate was added to 30 parts by weight of microcrystalline wax (trade name: Hi-Mis-3080, manufactured by Nippon Seiro Co., Ltd., melting point 84 ° C.), and dissolved by heating at 73 ° C. The wax was cooled and precipitated at 65 ° C. to obtain a crude wax dispersion. This crude wax dispersion, together with zirconia media with a diameter of 0.5 mm, was filled into a DCP mill SF-12 (manufactured by Nihon Eirich) and pulverized and / or dispersed until the unit accumulated power reached 0.20 kWh / kg. The liquid temperature is cooled to 5 ° C, and then the unit integrated power is 0.6 at the dispersion liquid temperature of 5 ° C.
It was pulverized and / or dispersed until it reached 5 kWh / kg to obtain an ethyl acetate dispersion of wax. The average particle size of the wax is LA-91
When measured with 0 (manufactured by Horiba Ltd.), it was 0.58 μm. When the wax shape in the wax dispersion liquid was observed with a scanning electron microscope (SEM) as in Example 1,
The average length of the major axis of the wax (a) was 0.64 μm, the average length of the minor axis of the wax was 0.55 μm, and the shape factor (f = a / b) was 1.16. .

Styrene-butyl acrylate 80/20
100 parts by weight of a copolymer resin (weight average molecular weight: 40,000, number average molecular weight: 15,000) of C.I. I. 6 parts by weight of Pigment Yellow 17, after 5 hours dispersed 1000 parts by weight of toluene in a sand mill, adding ethyl acetate dispersion 72 parts by weight of the word box, to prepare an oil phase liquid stirred well until uniform. 60 parts by weight of calcium carbonate and 40 parts by weight of water were dispersed in a ball mill for 10 hours to obtain a calcium carbonate dispersion liquid. 6 parts by weight of this calcium carbonate dispersion and 100 parts by weight of a 2% by weight aqueous solution of serogen BS-H (Daiichi Kogyo Seiyaku Co., Ltd.) in a tabletop colloid mill (manufactured by Nippon Seiki Seisakusho)
The mixture was mixed at 00 rpm for 5 minutes to prepare an aqueous phase liquid. 50 parts by weight of oil phase liquid was added to this water phase liquid, and the mixture was mixed at 20
After mixing for a minute, the organic solvent is removed under reduced pressure in a 25 ° C. water bath. 100 parts by weight of 6N hydrochloric acid was added to remove calcium carbonate, and then washed, dried and classified with water to have an average particle diameter of 7.4 μ.
m solid toner was obtained. The SEM photograph showed that the shape was almost spherical. To confirm the shape of the wax in the toner, the TEM photograph was observed in the same manner as in Example 1. As a result, the average length (a) of the major axes of the wax was 0.70 μm.
The short axis average length (b) of the wax was 0.58 μm, and the shape factor (f = a / b) was 1.21. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was dispersed inside the toner and was not visible on the surface of the toner particles. A silica external additive toner obtained by mixing 1 part by weight of silica R972 (manufactured by Nippon Aerosil) with 100 parts by weight of a toner in a sample mill for 1 minute was subjected to image evaluation without using a fixing fuser oil using A-color 935 (manufactured by Fuji Xerox). The results obtained are shown in Table 1.

Example 4 30 parts by weight of paraffin wax (trade name: HNP (high-purity purified paraffin wax) manufactured by Nippon Seiro, melting point 89 ° C.) was dissolved in 250 parts by weight of ethyl acetate by heating at 73 ° C., and then 60 The wax crude dispersion obtained by precipitating the wax by maintaining the temperature at ℃ was subjected to ultrasonic treatment (ultrasonic oscillation frequency 28 ± 2 kHz, ultrasonic oscillation output density 0.601 W / cm ² ) to obtain a crude wax dispersion. .
The wax crude dispersion at 25 ° C was filled in a DCP mill SF-12 (manufactured by Nihon Eirich) together with zirconia media having a diameter of 0.3 mm, and the unit integrated power was 0.70 kW.
The mixture was pulverized and / or dispersed until it became h / kg to obtain an ethyl acetate dispersion liquid of wax. At this time, the temperature of the wax dispersion liquid in the pulverization and / or dispersion area was 5 ° C.
The average particle diameter of the wax was 0.40 μm when measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba Ltd.). When the wax shape in the wax dispersion liquid was observed by a scanning electron microscope (SEM), the average length (a) of the long axes of the wax was 0.45 μm.
The short axis average length (b) of the wax was 0.39 μm, and the shape factor (f = a / b) was 1.15.

Styrene-butyl acrylate 80/20
100 parts by weight of a copolymer resin (weight average molecular weight: 40,000, number average molecular weight: 15,000), carbon black 5
After 1 part by weight and 1000 parts by weight of ethyl acetate were dispersed in a sand mill for 5 hours, 42 parts by weight of an ethyl acetate dispersion liquid of wax was added, and the mixture was well stirred until it became uniform to prepare an oil phase liquid. 60 parts by weight of calcium carbonate and 40 parts by weight of water were dispersed in a ball mill for 10 hours to obtain a calcium carbonate dispersion liquid. 6 parts by weight of this calcium carbonate dispersion and the serogen BS-H
100 parts by weight of a 2% by weight aqueous solution of (Daiichi Kogyo Seiyaku Co., Ltd.) is 5000 rp on a tabletop colloid mill (Nippon Seiki Seisakusho).
m and mixed for 5 minutes to prepare an aqueous phase liquid. To this aqueous phase solution, 50 parts by weight of the oil phase solution is added, and after mixing at 8000 rpm for 20 minutes, the organic solvent is removed under reduced pressure in a 25 ° C. water bath. 6
After 100 parts by weight of N hydrochloric acid was added to remove calcium carbonate, the solid was washed with water, dried and classified to obtain a solid toner having an average particle diameter of 7.4 μm. The SEM photograph showed that the shape was almost spherical. To confirm the wax shape in the toner,
When observed with a TEM photograph in the same manner as in Example 1,
The average length (a) of the major axis of the wax was 0.56 μm, the average length (b) of the minor axis of the wax was 0.48 μm, and the shape factor (f = a / b) was 1.17. . In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was dispersed inside the toner and was not visible on the surface of the toner particles.
Using 100 parts by weight of toner and 1 part by weight of silica R972 (manufactured by Nippon Aerosil) in a sample mill for 1 minute, an externally-added silica toner obtained by using A-color 935 (manufactured by Fuji Xerox) was evaluated without fixing fuser oil. The results obtained are shown in Table 1.

Example 5 30 parts by weight of paraffin wax (trade name: HNP (high-purity purified paraffin wax) manufactured by Nippon Seiro Co., Ltd., melting point 89 ° C.) was added with 250 parts by weight of ethyl acetate, heated and melted at 73 ° C., and cooled. 2 obtained by precipitation
An ethyl acetate dispersion of wax was obtained in the same manner as in Example 1, except that the temperature of the wax dispersion at 5 ° C. was 55 ° C. in the DCP mill and / or the dispersion region. The average particle size of the wax at this time was 2.0 μm as measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba Ltd.). Scanning electron microscope (SE
The average length of the major axis of the wax (a) was 2.20 μm, the average length of the minor axis of the wax (b) was 1.44 μm, and the shape factor (f = a / b) was observed.
Was 1.53. Thereafter, the same procedure as in Example 1 was carried out except that the wax dispersion was different, resulting in an average particle diameter of 7.3 μm.
m solid toner was obtained. The shape of the wax in the toner is TE
When observed in the M photograph, the average length of the major axis of the wax (a) is 2.57 μm, the average length of the minor axis of the wax (b) is 1.59 μm, and the shape factor (f = a / b).
Was 1.62. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax is dispersed inside the toner,
It was not visible on the surface of the toner particles.

A silica external additive toner obtained by mixing 1 part by weight of silica R972 (manufactured by Nippon Aerosil Co., Ltd.) with 100 parts by weight of the toner in a sample mill for 1 minute is A-color 935.
Table 1 shows the results of image evaluation using a fixing fuser oil (manufactured by Fuji Xerox).

Comparative Example 1 Styrene-butyl acrylate 80/20 copolymer resin (weight average molecular weight: 4000)
0, number average molecular weight: 15000) 100 parts by weight, C.I.
I. Pigment Red 57 (3 parts by weight) and paraffin wax (trade name: HNP (high-purity refined paraffin wax) manufactured by Nippon Seiro Co., Ltd., melting point 89 ° C.) (3 parts by weight) are added, and the mixture is kneaded and pulverized in a kneader and then classified to have an average particle diameter of 7 Solid toner of 0.8 μm was obtained. When the wax shape in the toner was observed by a TEM photograph, the average length (a) of the long axes of the wax was 2.7.
1 μm, average length of minor axis of wax (b) is 0.91 μm
m, and the shape factor (f = a / b) was 2.98. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was partially exposed on the surface of the toner particles. An external silica-added toner obtained by mixing 1 part by weight of silica R972 (manufactured by Nippon Aerosil) with 100 parts by weight of a toner in a sample mill for 1 minute was used to form an image using A-color 935 (manufactured by Fuji Xerox) without a fixing fuser oil. The results of the evaluation are shown in Table 1.

(Comparative Example 2) Comparative Example 2 except that the crude wax dispersion of Example 5 was treated with a Gorin homogenizer 15MR-8TA (Doei Shoji) at a pressure of 500 kg / cm ² and ^two passes. A wax ethyl acetate dispersion was obtained in the same manner as in 1. The temperature of the wax dispersion liquid during the Gohlin homogenizer treatment was 5 ° C. before the treatment and 45 ° C. after the treatment in both the one and two passes.
The average particle diameter of the wax at this time was 0.65 μm as measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba Ltd.). Observation of the wax shape in the wax dispersion with a scanning electron microscope (SEM) revealed that the average length (a) of the long axes of the wax was 1.1.
5 μm, average length of minor axis of wax (b) is 0.46 μm
m, and the shape factor (f = a / b) was 2.50. Thereafter, the same procedure as in Example 1 was carried out except that the wax dispersion was different, and as a result, a solid toner having an average particle diameter of 8.1 μm was obtained. Observation of the wax shape in the toner with a TEM photograph showed that the average length (a) of the long axis of the wax was 1.22 μm.
m, the average length of the minor axis of the wax (b) was 0.54 μm, and the shape factor (f = a / b) was 2.26. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was partially exposed on the surface of the toner particles.

A silica external additive toner obtained by mixing 1 part by weight of silica R972 (manufactured by Nippon Aerosil) with 100 parts by weight of the toner in a sample mill for 1 minute was A-color 935.
Table 1 shows the results of image evaluation using a fixing fuser oil (manufactured by Fuji Xerox).

Comparative Example 3 Similar to Example 5, except that the crude wax dispersion of Example 5 was treated with Nanomaker 200 (manufactured by Nanomizer) at a pressure of 500 kg / cm ² and three passes. To obtain a solid toner having an average particle diameter of 8.5 μm. The temperature of the wax dispersion during the nanomaker treatment was 5 ° C. before the treatment and 48 ° C. after the treatment in each of the 1 to 3 passes. The average particle size of the wax was 3.28 μm, the average length of the major axis (a) was 3.90 μm, and the average length of the minor axis of the wax (b) was 2.
It was 45 μm and the shape factor (f = a / b) was 1.59.

Styrene-butyl acrylate 80/20
50 parts by weight of a copolymer resin (weight average molecular weight: 40,000, number average molecular weight: 15,000) of C.I. I. Pigment Yellow 17 (6 parts by weight) and toluene (500 parts by weight) are dispersed in a sand mill for 5 hours, and then a wax ethyl acetate dispersion 30 is prepared.
An oil phase liquid was prepared by adding 7.7 parts by weight and thoroughly stirring until uniform. 60 parts by weight of calcium carbonate and 40 parts by weight of water were dispersed in a ball mill for 10 hours to obtain a calcium carbonate dispersion liquid. 6 parts by weight of this calcium carbonate dispersion and a 2% by weight aqueous solution of serogen BS-H (Daiichi Kogyo Seiyaku Co., Ltd.) 100
5 parts by weight on a tabletop colloid mill (Nippon Seiki Seisakusho)
The mixture was mixed at 000 rpm for 5 minutes to prepare an aqueous phase liquid. 50 parts by weight of oil phase liquid was added to this water phase liquid at 8000 rpm,
After mixing for 20 minutes, the organic solvent was removed under reduced pressure in a 25 ° C. water bath. 6. Add 100 parts by weight of 6N hydrochloric acid to remove calcium carbonate, then wash with water, dry and classify to obtain an average particle size of 7.
8 μm solid toner was obtained. The SEM photograph showed that the shape was almost spherical. The average length of the major axis of the wax in the toner (a) is 3.25 μm, the average length of the minor axis of the wax (b) is 1.31 μm, and the shape factor (f = a /
b) was 2.48. In a transmission electron microscope (TEM) photograph of the cross section of the toner, the wax was dispersed inside the toner and was not visible on the surface of the toner particles.

A silica external additive toner obtained by mixing 1 part by weight of silica R972 (manufactured by Nippon Aerosil) with 100 parts by weight of a toner in a sample mill for 1 minute was prepared by using A-color 935 (manufactured by Fuji Xerox) without fixing fuser oil. Table 1 shows the results of the image evaluation performed with.

[0042]

[Table 1]

[0043]

As described above, according to the present invention,
The toner is excellent in offset resistance, charging property, fluidity, fixing property and cycle stability, and also has good color forming property and OHP transparency, and it is possible to obtain good image quality.
At the same time, the shape of the toner can be controlled, spherical particles can be easily formed, and a toner having good transferability and cleaning property was obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-153361 (JP, A) JP-A-2-173666 (JP, A) JP-A-6-63387 (JP, A) JP-A-6- 75429 (JP, A) JP-A-6-161145 (JP, A) JP-A-6-242633 (JP, A) JP-A-6-273977 (JP, A) JP-A-8-328293 (JP, A) JP-A-9-15902 (JP, A) JP-A-9-15903 (JP, A) JP-A-9-73187 (JP, A) JP-A-9-134027 (JP, A) JP-A-10-186714 (JP, A) JP 10-198065 (JP, A) JP 10-207119 (JP, A) JP 63-25664 (JP, A) JP 63-300245 (JP, A) (JP 58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (11)

(57) [Claims] 1. A step of dissolving or dispersing at least a binder resin, a colorant, and a release agent in an organic solvent capable of dissolving the binder resin to prepare an oil phase component, and the oil phase component being an aqueous medium. In a toner for electrophotography manufactured by a manufacturing method including a step of dispersing and granulating the particles, the release agent is dissolved in an organic solvent in advance and then deposited, or suspended in an organic solvent in advance. A toner for electrophotography, which is a dispersion liquid of a release agent obtained by crushing and / or dispersing with a medium after being applied. 2. Grinding and / or dispersing with media
The spherical fine particles of the release agent thus obtained have an average particle diameter of 0.01.
2. The toner for electrophotography according to claim 1, wherein the toner is spherical fine particles having a shape in the range of 1 to 1.5 μm and a shape satisfying the shape factor (f) of the following formula (1). F ≦ 1.25 (1) (where, f = a / b, a is the average length of the major axis of the release agent particles, and b is the minor axis of the release agent particles. Represents the average length of.) 3. Grinding and / or dispersing with media
The spherical fine particles of the releasing agent thus obtained have an average particle size in the range of 0.1 to 0.5 μm and a shape of the following formula (1).
2. The toner for electrophotography according to claim 1, wherein the toner is spherical fine particles satisfying the shape factor (f). F ≦ 1.25 (1) (where f = a / b, a is the average length of the major axis of the release agent particles, and b is the short axis of the release agent particles) Represents the average length of.) 4. The electrophotographic toner according to claim 1, wherein the binder resin is a polyester resin. 5. The electrophotographic toner according to claim 1, wherein the releasing agent has a melting point of 120 ° C. or lower. 6. The toner for electrophotography according to claim 1, wherein the release agent is contained in an amount of 0.5 to 15 parts by weight with respect to 100 parts by weight of the binder resin. 7. A step of dissolving or dispersing at least a binder resin, a colorant, and a release agent in an organic solvent capable of dissolving the binder resin to prepare an oil phase component, and the oil phase component being an aqueous medium. In a method for producing an electrophotographic toner including a step of dispersing and granulating therein, a release agent dispersed in an organic solvent in which the binder resin is dissolved is previously dissolved in the organic solvent and then deposited. Alternatively, a method for producing an electrophotographic toner, which is a dispersion liquid of a release agent obtained by pulverizing and / or dispersing with a medium after being previously suspended in an organic solvent. 8. The temperature of the dispersion liquid containing at least the release agent and the organic solvent is kept at 40 ° C. or lower when the release agent is pulverized and / or dispersed with a medium. Method for producing toner for electrophotography. 9. Fine particles of a release agent of a release agent dispersion liquid obtained by crushing and / or dispersing with a medium have an average particle diameter in the range of 0.01 to 1.5 μm and have the following shape. The method for producing an electrophotographic toner according to claim 7, which is spherical fine particles satisfying the shape factor (f) of the formula (1). F ≦ 1.25 (1) (where f = a / b, a is the average length of the major axis of the release agent particles, and b is the minor axis of the release agent particles) Represents the average length of.) 10. The method according to claim 7, wherein 1 to 20 parts by weight of an organic solvent is used with respect to 1 part by weight of the release agent in the step of pulverizing and / or dispersing the release agent with a medium. Method for producing toner for electrophotography. 11. An image forming method including a step of forming a latent image on an image carrier, a step of developing the latent image with a developer, and a step of transferring a toner image formed by the development onto a transfer body. 7. The image forming method according to claim 7, wherein the developer contains the toner according to any one of claims 1 to 6.