JP2008216502A - Toner, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner capable of achieving high resolution of a printed image and giving a high-quality printed image while solving various problems of toner with a small particle size, and to provide a developing device and an image forming apparatus. <P>SOLUTION: The toner contains: resin base particles composed of a colorant and a binder resin; and silicone oil and/or fluorine oil. The toner is characterized in that: the volume average particle diameter of the resin base particles ranges from 2 to 4 μm; the circularity of the resin base particles ranges from 0.97 to 0.99; and the add amount of the silicone oil and/or fluorine oil to the resin base particles ranges from 0.05 to 2 mass%. It is preferable that Dv/Dn ranges from 1 to 1.1, wherein Dv and Dn represent the volume average particle diameter and the number average particle diameter of the toner, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner, a developing device, and an image forming apparatus.

In general, an image forming apparatus such as a printer, a copying machine, or a facsimile machine that employs an electrophotographic method generally uses a series of image forming processes including a charging process, an exposure process, a development process, a transfer process, and a fixing process to form an image made of toner. Formed on a recording medium.
Such an image forming apparatus is provided with a developing device having a developing roller for carrying toner. Such a developing device is used in a state in which a developing roller is opposed to a photosensitive drum carrying an electrostatic latent image. By applying toner from the developing roller to the photosensitive drum, the latent image on the photosensitive drum is converted into a toner image. Visualize (develop).

Incidentally, in recent years, it has been proposed to use a toner having a small particle diameter of 4 μm or less as the resolution of a printed image increases. However, in the case of a dry toner, if the particle size is simply reduced, the toner easily scatters, and it is difficult to carry the toner on the developing roller, resulting in a problem in transportability.
On the other hand, conventionally, there has been known a toner in which a small amount of oil is added (externally added) to resin base particles composed of a binder resin and a colorant in order to prevent toner filming on the photosensitive drum and the developing roller. (For example, refer to Patent Document 1).

Even if the toner to which oil has been added in this way, even if the particle size is reduced, the resin mother particles are aggregated by the oil to form an aggregate to increase the apparent particle size. It is thought that the problem caused by the reduction in particle size can be solved.
However, in such a toner, the particle diameters of the aggregates of the resin mother particles vary, so that the chargeability of the toner tends to be non-uniform, which may adversely affect development characteristics and transfer characteristics. In particular, such an adverse effect is conspicuous in a small particle size toner, and it is difficult to achieve high resolution of a printed image even if oil is simply added to the small particle size toner.

JP 2001-166527 A

  An object of the present invention is to provide a toner, a developing device, and an image forming apparatus capable of obtaining a high-quality print image by increasing the resolution of a print image while solving various problems of small particle size toner. is there.

Such an object is achieved by the present invention described below.
The toner of the present invention comprises resin mother particles comprising a colorant and a binder resin,
Silicone oil and / or fluorine oil,
The volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin base particles represented by the following formula (I) is 0.97 to 0.99,
The amount of the silicone oil and / or fluorine oil added to the resin base particles is 0.05 to 2% by mass.
R = L ₀ / L ₁ (I)
(Wherein, L ₁ [μm] is the circumference of the projected image of the resin base particle to be measured, and L ₀ [μm] is a perfect circle having an area equal to the area of the projected image of the resin base particle to be measured. Represents the perimeter of
As a result, it is possible to provide a toner that can improve the resolution of the print image and obtain a high-quality print image while solving various problems of the small particle size toner.

In the toner of the present invention, it is preferable that Dv / Dn is 1 to 1.1 when the volume average particle diameter of the toner is Dv and the number average particle diameter of the toner is Dn.
Thereby, an appropriate gap can be formed between the resin mother particles. As a result, the resin base particles are aggregated by the liquid crosslinking force of silicone oil or fluorine oil, and an aggregate (soft aggregate) can be more suitably formed. Such agglomerates are unlikely to be crushed in the toner container of the developing device or on the developing roller and behave like a large particle size toner, but reciprocate between the developing roller and the photosensitive drum during non-contact jumping development. It is easy to be crushed. Therefore, it can behave like a small particle size toner on the photosensitive drum, and as a result, the resolution and gradation of the printed image can be improved.

The toner of the present invention, the bulk density of the resin base particles ^is preferably ^{0.25g / cm 3 ~0.35g / cm 3} .
Thereby, the clearance gap between resin mother particles can be made more moderate, and resin mother particles can aggregate and can form an aggregate (soft aggregate) more suitably.
The toner of the present invention preferably contains inorganic fine particles as an external additive.
Thereby, the fluidity of the toner can be improved and the charging characteristics can be made particularly excellent.

In the toner of the present invention, a first step of obtaining a colored resin liquid by dissolving or dispersing at least a binder resin and a colorant in an organic solvent;
A second step of obtaining an emulsified suspension obtained by emulsifying the colored resin liquid in an aqueous medium by sequentially adding a basic compound and water to the colored resin liquid;
A third step of coalescing the dispersoid in the emulsion suspension by adding an aqueous electrolyte solution to the emulsion suspension to obtain coalesced particles;
After removing the organic solvent, the coalesced particles are separated from the aqueous medium, washed, and dried to obtain the resin mother particles;
It is preferable to manufacture using the method which has a 5th process of adding the said silicone oil or fluorine oil to the said resin mother particle obtained.
Accordingly, it is possible to more suitably provide a toner that can improve the resolution of a printed image and obtain a high-quality printed image while solving various problems of small particle size toner.

In the toner of the present invention, the residual amount of the organic solvent is preferably 5 to 50 ppm.
Thereby, since the liquid crosslinking force by a silicone oil or fluorine oil can be made more appropriate, generation | occurrence | production of the strongly aggregated aggregate can be prevented effectively. As a result, development efficiency and transfer efficiency can be improved, and a uniform image can be formed.

The developing device of the present invention includes a toner storage unit that stores toner,
A developing roller having a function of carrying the toner on the outer peripheral surface;
The toner includes resin base particles including a colorant and a binder resin;
Silicone oil and / or fluorine oil,
The volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin base particles represented by the following formula (I) is 0.97 to 0.99,
The amount of the silicone oil and / or fluorine oil added to the resin base particles is 0.05 to 2% by mass.
Accordingly, it is possible to provide a developing device capable of solving the problems of the small particle size toner and increasing the resolution of the print image and obtaining a high-quality print image.

An image forming apparatus of the present invention includes a latent image carrier that carries a latent image;
A developing device that visualizes the latent image as a toner image by applying toner to the latent image carrier;
The developing device includes a toner storage unit that stores toner;
A developing roller having a function of carrying the toner on the outer peripheral surface thereof, facing the latent image carrier in the vicinity.
The toner includes resin base particles including a colorant and a binder resin;
Silicone oil and / or fluorine oil,
The volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin base particles represented by the following formula (I) is 0.97 to 0.99,
The amount of the silicone oil and / or fluorine oil added to the resin base particles is 0.05 to 2% by mass.
Accordingly, it is possible to provide an image forming apparatus capable of obtaining a high-quality print image by increasing the resolution of the print image while solving various problems of the small particle size toner.

Hereinafter, preferred embodiments of the toner, the developing device, and the image forming apparatus of the present invention will be described.
<Toner>
First, the toner of the present invention will be described.
The toner of the present invention is obtained by adding (externally adding) silicone oil and / or fluorine oil to resin base particles composed of a binder resin and a colorant.

Particularly, in the toner of the present invention, the volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin book particles represented by the following formula (I) is 0.97 to 0.99. The amount of silicone oil and / or fluorine oil added to the resin base particles is 0.05 to 2% by mass.
R = L ₀ / L ₁ (I)
(Wherein, L ₁ [μm] is the circumference of the projected image of the resin base particle to be measured, and L ₀ [μm] is a perfect circle having an area equal to the area of the projected image of the resin base particle to be measured. Represents the perimeter of

  In such a toner, although the resin base particles have a small particle diameter, silicone oil or fluorine oil is externally added, so that the resin base particles form aggregates as secondary particles by the liquid crosslinking force. However, it behaves like a resin mother particle having a large particle size in a toner container of a developing device or a developing roller as will be described later. Therefore, it is possible to prevent toner scattering and to improve toner transportability. Moreover, the resin mother particles can be obtained by setting the circularity of the resin mother particles to 0.97 to 0.99, and adding the silicone oil and / or fluorine oil to the resin mother particles in an amount of 0.05 to 2% by mass. An appropriate amount of silicone oil or fluorine oil can be present between them, and the liquid crosslinking force by the silicone oil or fluorine oil can be made moderate. As a result, it is possible to ensure the fluidity necessary for charging and to prevent variation in the particle diameter of the formed aggregate. Furthermore, the aggregate of the resin mother particles can be formed as a soft aggregate. Such soft agglomerates are easily crushed by reciprocating movement between the developing roller and the photosensitive drum during non-contact jumping development as described later, so that an image as described later is obtained. In the forming apparatus, it can behave like a small particle size toner on the photosensitive drum, and as a result, the resolution and gradation of the printed image can be improved.

(Resin mother particles)
First, the resin base particles will be described.
The resin mother particles are configured to include a colorant and a binder resin.
The binder resin is not particularly limited, but a polyester resin such as a cross-linked polyester resin or a linear polyester resin is preferably used. The polyester resin will be described in detail later.
Moreover, it does not specifically limit as a coloring agent, Various pigments, various dyes, etc. can be used.
Moreover, the content of the colorant with respect to the resin mother particles is not particularly limited, but is preferably 10 to 20% by mass.

Such resin mother particles preferably contain a wax in addition to the colorant and binder resin described above.
In addition, the resin mother particles may contain components other than the components described above.
Such resin mother particles have a volume average particle diameter of 2 to 4 μm.
Thus, by reducing the volume average particle size of the resin base particles to 4 μm or less and reducing the particle size, the resolution and gradation of the printed image can be improved. Further, the thickness of the toner layer for forming the printed image can be reduced to suppress the heat amount and toner consumption necessary for fixing.
On the other hand, if the volume average particle diameter of the resin base particles is less than 2 μm, the resin base particles need to contain 20% by mass or more of a colorant, and the fixability is caused by insufficient binder resin content. Will be greatly reduced.

  Further, when the volume average particle diameter of the resin mother particles is Dv and the number average particle diameter of the resin mother particles is Dn, Dv / Dn is preferably 1 to 1.1. Thereby, an appropriate gap can be formed between the resin mother particles. As a result, the resin base particles are aggregated by the liquid crosslinking force of silicone oil or fluorine oil, and an aggregate (soft aggregate) can be more suitably formed. Such agglomerates are unlikely to be crushed in the toner container or on the developing roller in the developing device, which will be described in detail later, and behave like a large particle size toner. Easily crushed by reciprocating between drums. Therefore, it can behave like a small particle size toner on the photosensitive drum, and as a result, the resolution and gradation of the printed image can be improved.

On the other hand, when Dv / Dn is less than 1 or exceeds 1.1, the resin base particles having a small particle size enter between the resin base particles having a large particle size so that the small particle size and the large particle Resin mother particles having a diameter form aggregates. Since such an aggregate has a small gap between the resin base particles, the resin base particles are strongly aggregated due to a liquid crosslinking force by silicone oil or fluorine oil. Therefore, such agglomerates are not crushed even when reciprocating between the developing roller and the photosensitive drum during non-contact jumping development as described later, thereby improving the resolution and gradation of the printed image. I can't.
Further, as described above, when Dv / Dn is 1 to 1.1, the bulk density of the resin base particles alone does not exceed 0.25 g / cm ³ , but silicone oil or fluorine oil is added to the resin base particles. By adding, the bulk density of the toner can be made 0.25 g / cm ³ or more.

  Moreover, the circularity represented by the above formula (I) of the resin mother particles is 0.97 to 0.99. When the circularity is 0.97 to 0.99, which is close to a true sphere, the amount of silicone oil or fluorine oil between the resin base particles can be made more appropriate, and the liquid crosslinking force by silicone oil or fluorine oil can be increased. It can be made more appropriate. Further, since the silicone oil or the fluorine oil can be more uniformly dispersed, it is possible to effectively prevent the variation in the particle size of the formed aggregate, and the variation in the charging characteristics, development characteristics, etc. of the toner is particularly significant. As a result, the reliability of the toner as a whole is further improved.

Further, the upper limit of the bulk density of the toner is preferably less than 0.35 g / cm ³ . When the bulk density of the toner exceeds 0.35 g / cm ³ , the gap between the resin base particles becomes small, and an aggregate in which the resin base particles are firmly aggregated is formed by the liquid crosslinking force by silicone oil or fluorine oil. End up. Such agglomerates are not crushed even when reciprocating between the developing roller and the photosensitive drum during non-contact jumping development as described later, and the resolution and gradation of the printed image cannot be improved. .

(Silicone oil / Fluorine oil)
The silicone oil contained in the toner is not particularly limited. For example, hydrogen silicone oil, phenyl silicone oil, amino silicone oil, epoxy silicone oil, carboxy silicone oil, polyether silicone oil, hydrophilic silicone oil, methacrylic silicone oil. Mercapto silicone oil, one-end reactive silicone oil, higher alkoxy silicone oil, alkyl silicone oil, and the like can be used.
Further, the fluorine oil contained in the toner is not particularly limited, and for example, perfluoropolyether, polytrifluoroethylene chloride, or the like can be used.

  In particular, the amount of silicone oil or fluorine oil added to the resin base particles is 0.05 to 2% by mass. As a result, the resin base particles can be moistened moderately and uniformly to prevent the toner from being scattered and to prevent variation in the particle diameter of the formed aggregates. As a result, variations in toner charging characteristics, development characteristics, etc. can be made smaller, and easier due to reciprocating motion between the developing roller and the photosensitive drum during non-contact jumping development as described later. Aggregates (soft agglomerates) that can be crushed into pieces can be formed.

  On the other hand, if the amount of silicone oil or fluorine oil added to the resin base particles is less than 0.05% by mass, the resin base particles do not softly agglomerate and the aggregates of the resin base particles (secondary particles) Can't get. On the other hand, when the amount of silicone oil or fluorine oil added to the resin base particles exceeds 2% by mass, the resin base particles are strongly aggregated, and the obtained aggregate (secondary particles) is non-contact as described above. Even during reciprocating movement between the developing roller and the photosensitive drum during jumping development, the image is not crushed and the resolution and gradation of the printed image cannot be improved.

Further, the toner may contain inorganic fine particles such as silica and titanium oxide as external additives. Thereby, the fluidity of the toner can be improved and the charging characteristics can be made particularly excellent.
The inorganic fine particles are preferably subjected to a hydrophobic treatment. Thereby, the fluidity and chargeability of the toner can be further improved.

  Hydrophobization is achieved by using silane compounds such as aminosilane, hexamethyldisilazane, and dimethyldichlorosilane; silicone oils such as dimethyl silicone, methylphenyl silicone, fluorine-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, and epoxy-modified silicone oil. It is carried out by a method usually used by those skilled in the art, such as a wet method and a dry method.

The toner as described above can be manufactured, for example, as follows.
A method for producing such a toner includes:
A first step (colored resin solution preparation step) of obtaining a colored resin solution by dissolving or dispersing at least a binder resin and a colorant in an organic solvent;
A second step (emulsification step) of obtaining an emulsified suspension obtained by emulsifying the colored resin solution in an aqueous medium by sequentially adding a basic compound and water to the colored resin solution;
A third step (a coalescence step) to obtain coalesced particles by coalescing the dispersoids in the emulsion suspension by adding an aqueous electrolyte solution to the emulsion suspension;
After removing the organic solvent, the coalesced particles are separated from the aqueous medium, washed and dried to obtain resin mother particles (separation / drying step);
The obtained resin base particles have a fifth step (external addition step) in which an external additive such as silica fine particles and silicone oil or fluorine oil are added to obtain a toner.

Hereafter, each process is demonstrated in detail sequentially.
<First step>
In this step (colored resin solution preparation step), first, a binder resin, a colorant, and, if necessary, wax are introduced into an organic solvent and dissolved or dispersed to obtain a colored resin solution.
In dissolving or dispersing the binder resin, the colorant, and the wax in the organic solvent, it is preferable to use a high-speed stirrer. At that time, a master kneading chip in which a colorant is predispersed can be used. Further, a master kneading chip in which wax is preliminarily dispersed, or a wax master solution finely dispersed to a toner particle size or less by wet dispersion using media can be used.

  As a high-speed stirrer used in the colored resin liquid preparation step, Desper (Asada Iron Works Co., Ltd.), T.M. K. A homomixer (manufactured by Primix Co., Ltd.) can be used. The blade tip speed of such a high-speed stirrer is preferably 4 to 30 m / s, and more preferably 8 to 25 m / s. By using such a high-speed stirrer, the binder resin can be efficiently dissolved in the organic solvent, and uniform fine dispersion of the colorant in the binder resin solution can be realized. That is, the state of the colorant finely dispersed in advance can be maintained in the binder resin solution by stirring at high speed.

On the other hand, if the blade tip speed is less than the lower limit, depending on the type of organic solvent or colorant used, fine dispersion of the colorant in the binder resin solution may be insufficient. On the other hand, when the blade tip speed exceeds the upper limit, heat generation due to shearing increases, and it may be difficult to perform uniform stirring in combination with volatilization of the organic solvent.
Moreover, the processing temperature in the colored resin liquid adjustment step is not particularly limited, but is preferably in the range of 20 to 60 ° C, more preferably in the range of 30 to 50 ° C.
The solubility of the organic solvent in water at 25 ° C. is not particularly limited, but is preferably 0.1 to 30% by mass, and more preferably 0.1 to 25% by mass.

  Since the boiling point of the organic solvent at normal pressure is lower than the boiling point of water, examples of the organic solvent having the above-described solubility include ketones such as methyl ethyl ketone and methyl isopropyl ketone, and esters such as ethyl acetate and isopropyl acetate. And the like. These organic solvents can be used by mixing two or more kinds of organic solvents, but it is preferable to use one kind of organic solvent alone from the viewpoint of solvent recovery. The organic solvent is preferably a low-boiling organic solvent that dissolves the binder resin and easily removes the solvent in a subsequent process. From such a viewpoint, it is preferable to use methyl ethyl ketone as the organic solvent.

In the colored resin liquid adjusting step, an emulsifier can be added to the organic solvent together with the binder resin, the colorant, and the wax.
In order for the emulsifier to function in the coalescence step described later, it is necessary to have a characteristic that can maintain dispersion stability even in the presence of an electrolyte added later. Examples of emulsifiers having such properties include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene Nonionic emulsifiers such as oxyethylene sorbitan fatty acid esters and various pluronics; alkyl sulfate ester type, alkyl sulfonate type anionic emulsifiers; quaternary ammonium salt type cationic emulsifiers; alkyl benzene sulfonate type emulsifiers, direct And chain alkylbenzene sulfonic acid type emulsifier. Such emulsifiers may be used alone or in combination of two or more.

By using such an emulsifier, non-uniform coalescence can be effectively prevented when an electrolyte is added in the coalescence process described later. As a result, a toner having a preferable particle size distribution can be obtained.
The amount of the emulsifier to be used is preferably 0.1 to 3.0% by mass, more preferably 0.3 to 2.0% by mass with respect to the solid content, and 0.3 to 1.%. More preferably, it is 5 mass%.

  When the amount of the emulsifier to be used is less than the lower limit value, there may be a case where the desired effect of preventing the generation of coarse particles may not be obtained depending on the type of emulsifier. On the other hand, when the amount of the emulsifier used exceeds the upper limit, depending on the type of the emulsifier, even if the amount of the electrolyte is increased, the coalescence of the dispersoid in the emulsified suspension does not proceed sufficiently, and the predetermined particle size As a result, fine particles may remain and the yield may decrease.

The binder resin is not particularly limited as described above, but it is preferable to use a polyester resin such as a cross-linked polyester resin or a linear polyester resin.
As the polyester resin, it is preferable to use a polyester resin having an acid value of 3 to 30 KOHmg / g, and it is more preferable to use a polyester resin having an acid value of 5 to 20 KOHmg / g.

A polyester resin having an acid value in the above range becomes an anionic type by neutralizing a carboxyl group with a basic compound. Therefore, the hydrophilicity of the binder resin is increased and can be stably dissolved or dispersed.
On the other hand, when the acid value of the polyester resin is less than the lower limit, it may be difficult to reliably produce resin mother particles having a desired shape. On the other hand, when the acid value of the polyester resin exceeds the upper limit, the toner obtained may not have a stable charge amount under the toner usage environment.

Such a polyester resin can be obtained, for example, as follows.
The cross-linked polyester can be produced by reacting a divalent basic acid or a derivative thereof, a divalent alcohol, and a polyvalent compound (crosslinking agent). The linear polyester resin can be produced by reacting a divalent basic acid with a dihydric alcohol.

  Examples of the divalent basic acid used in producing the crosslinked polyester resin or the linear polyester resin include phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, adipic acid, maleic acid, maleic anhydride, and fumaric acid. , Itaconic acid, citraconic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, azelaic acid, sebacic acid and the like.

  Moreover, it is preferable to use a bivalent aliphatic alcohol as a dihydric alcohol used when manufacturing a crosslinked type polyester resin. A polyester resin produced using a divalent aliphatic alcohol has good compatibility with waxes, and a developer containing resin mother particles having the polyester resin as a binder resin has high offset resistance. Moreover, fixing property at low temperature is improved by softening the polyester main chain.

  Examples of the divalent aliphatic alcohol include 1,4-cyclohexanedimethanol, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, butanediol, pentanediol, and hexanediol. Polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide random copolymer diol, ethylene oxide-propylene oxide block copolymer diol, ethylene oxide-tetrahydrofuran copolymer diol, polycaprocactone diol, and the like.

Moreover, it is preferable to use a polyvalent epoxy compound as the polyvalent compound (crosslinking agent) used when the cross-linked polyester resin is produced.
Examples of the polyvalent epoxy compound include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, ethylene glycol diglycidyl ether, hydroquinone diglycidyl ether, N, N-diglycidyl aniline lysine triglycidyl ester, Trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetrakis 1,1,2,2 (P-hydroxyphenyl) ethanetetraglycidyl ether, cresol novolac epoxy resin, phenol novolac epoxy resin , Vinyl compound polymer having an epoxy group, epoxidized resorcinol-acetone condensate, partially epoxidized polybutadiene And polymers of vinyl compounds having an epoxy group, semi-dry or dry fatty acid ester epoxy compounds, and the like.

  Among the above compounds, the polyvalent epoxy compounds include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, glycerin / triglycidyl ether, tri It is preferable to use methylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, or pentaerythritol tetraglycidyl ether.

Examples of the bisphenol A type epoxy resin include Epicron 850, Epicron 1050, Epicron 2055, Epicron 3050 and the like manufactured by Dainippon Ink and Chemicals, Inc.
Examples of the bisphenol F type epoxy resin include Epicron 830 and Epicron 520 manufactured by Dainippon Ink and Chemicals, Inc.

Examples of the ortho-cresol novolac type epoxy resin include, for example, Epicron N-660, N-665, N-667, N-670, N-673, N-680, N-690 manufactured by Dainippon Ink & Chemicals, Inc. , N-695 and the like.
Examples of the phenol novolac type epoxy resin include Epicron N-740, N-770, N-775, and N-865 manufactured by Dainippon Ink and Chemicals, Inc.
Examples of the polymer of the vinyl compound having an epoxy group include a glycidyl (meth) acrylate copolymer, a glycidyl (meth) acrylate-acrylic copolymer, a glycidyl (meth) acrylate-styrene copolymer, and the like. It is done.

Moreover, the polyvalent epoxy compound mentioned above may be used individually by 1 type, and may be used in combination of 2 or more type.
Moreover, when using a polyvalent epoxy compound, a monoepoxy compound can be used together as a modifier for the resin. By using the monoepoxy compound in combination, it is possible to improve the toner fixability and high temperature offset resistance.

Examples of the monoepoxy compound include phenyl glycidyl ether, alkylphenyl glycidyl ether, alkyl glycidyl ether, alkyl glycidyl ester, glycidyl ether of an alkylphenol alkylene oxide adduct, α-olefin oxide, monoepoxy fatty acid alkyl ester, and the like.
Among these, it is preferable to use an alkyl glycidyl ester as the monoepoxy compound.
Examples of the alkyl glycidyl ester include Cardura E (Neodecanoic acid glycidyl ester manufactured by Shell Chemicals Japan Co., Ltd.).

The cross-linked polyester resin and the linear polyester resin can be obtained by performing a dehydration condensation reaction or a transesterification reaction in the presence of a catalyst using the above-described raw material components, respectively.
The reaction temperature and reaction time are not particularly limited, but are usually 150 to 300 ° C. and 2 to 24 hours.
Moreover, a catalyst can be used for this reaction. Examples of the catalyst include tetrabutyl titanate, zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, and paratoluenesulfonic acid.

  As a binder resin, when a mixture of a cross-linked polyester resin and a linear polyester resin is used, the mixing ratio (the mass of the cross-linked polyester resin) / (the mass of the linear polyester resin) is not particularly limited. It is preferably 5/95 to 60/40, more preferably 10/90 to 40/60, and even more preferably 20/80 to 40/60.

  If (mass of cross-linked polyester resin) / (mass of linear polyester resin) is less than 5/95, the hot offset resistance of the toner, the coalescence speed in the coalescence process described later, wax, colorant, etc. Dispersibility of the additive in the resin base particles is reduced. On the other hand, if (the mass of the cross-linked polyester resin) / (the mass of the linear polyester resin) is more than 60/40, the melt viscosity (T1 / 2 temperature) of the resin base particles increases, and the resin base particles The low-temperature fixability of the resin deteriorates.

The glass transition temperature (Tg) of the cross-linked polyester resin is not particularly limited, but is preferably 40 to 85 ° C, and more preferably 60 to 80 ° C.
When the Tg of the cross-linked polyester resin is lower than 40 ° C., a blocking phenomenon (thermal aggregation) tends to occur when the resin mother particles are stored, transported, or exposed to a high temperature inside the developing device. On the other hand, when the Tg of the cross-linked polyester resin is higher than 85 ° C., the low-temperature fixability of the resin mother particles is lowered.

Although the glass transition temperature (Tg) of a linear polyester resin is not specifically limited, It is preferable that it is 35-70 degreeC, and it is more preferable that it is 50-65 degreeC.
When the Tg of the linear polyester resin is lower than 35 ° C., a blocking phenomenon (thermal aggregation) tends to occur when the resin mother particles are stored, transported, or exposed to a high temperature inside the developing device. On the other hand, when the Tg of the linear polyester resin is higher than 70 ° C., the low-temperature fixability of the resin mother particles is lowered.

The softening point of the cross-linked polyester resin is not particularly limited, but is preferably 150 ° C or higher, more preferably 150 ° C to 220 ° C, and further preferably 170 ° C to 190 ° C.
When the softening point of the cross-linked polyester resin is less than 150 ° C., the resin mother particles tend to aggregate, and troubles are likely to occur during storage and printing. On the other hand, when the softening point of the cross-linked polyester resin exceeds 220 ° C., the fixing property of the resin base particles is lowered.

The softening point of the linear polyester resin is not particularly limited, but is preferably 90 ° C or higher, more preferably 90 ° C to 130 ° C, and further preferably 90 ° C to 110 ° C.
When the softening point of the linear polyester resin is less than 90 ° C., the glass transition temperature of the linear polyester resin decreases, the resin mother particles tend to aggregate, and troubles occur during storage and printing. . On the other hand, when the softening point of the linear polyester resin exceeds 130 ° C., the fixing property of the resin mother particles is lowered.
The softening point of the polyester resin is a T1 / 2 temperature measured using a constant load extrusion type capillary rheometer (Flow Tester CFT-500 manufactured by Shimadzu Corporation). The measurement is performed under the conditions of a piston cross-sectional area of 1 cm ² , a cylinder pressure of 0.98 MPa, a die length of 1 mm, a die hole diameter of 1 mm, a measurement start temperature of 50 ° C., a temperature increase rate of 6 ° C./min, and a sample mass of 1.5 g. .

Moreover, the measurement of the glass transition temperature (Tg) of a polyester resin is measured using DSC (Shimadzu DSC-60A). 20 mg of sample is put in an aluminum crimp cell, heated to 180 ° C. at a heating rate of 10 ° C./min, cooled to room temperature at a cooling rate of 10 ° C./min from 180 ° C., and again to 180 ° C. at a heating rate of 10 ° C./min The temperature rise and the second run value are Tg.
The colored resin liquid as described above can be prepared by mixing a charge control agent.

<Second step>
In this step (emulsification step), a basic compound and water are sequentially added to the colored resin liquid obtained in the first step described above to emulsify the colored resin liquid in an aqueous medium. As a result, a dispersion (emulsified suspension) is obtained in which the dispersoid composed of the binder resin and the colorant is dispersed (emulsified and / or suspended).

  At that time, it is preferable to gradually add water to the colored resin liquid in which the carboxyl group of the binder resin is neutralized by the basic compound. By neutralizing the carboxyl group, the hydrophilicity of the binder resin is improved, and the affinity between water and the binder resin can be improved. The added water is hydrated to the carboxyl group portion of the binder resin, and the binder resin is dissolved or finely dispersed in combination with the stirring effect. On the other hand, the binder resin intervenes in the aqueous medium to increase the acid-base interaction, and the viscosity of the system containing the colored resin liquid increases with the addition of water. When a certain amount of water is added, there is a point that the viscosity decreases, which is called a so-called phase inversion point. The viscosity increases until just before this, and the viscosity reaches the maximum value. The increase in viscosity correlates with the addition amount of the basic compound, and the increase in viscosity increases as the addition amount increases.

On the other hand, the amount of the basic compound affects not only the emulsification step of the second step, but also the uniformity and speed when the colored resin fine particles are produced in the coalescence step of the third step described later.
The amount of the basic compound added to the carboxyl group of the binder resin is preferably in the range of 1 to 3 equivalents, and more preferably in the range of 1 to 2 equivalents. By adding the basic compound in excess of the amount required to neutralize all of the carboxyl groups of the binder resin, it is possible to prevent the formation of irregularly shaped particles in the coalescence process, and the resin The particle size distribution of the mother particles can be made narrow. That is, a toner having a sharp particle size distribution can be formed.

The ratio of the organic solvent to the total amount of the organic solvent and water after completion of the emulsification step is preferably in the range of 20 to 35% by mass, and more preferably in the range of 20 to 30% by mass. As described above, the amount of water up to the phase inversion point decreases as the amount of organic solvent in the colored resin liquid preparation step decreases, and increases as the amount of basic compound increases. At the phase inversion point, the viscosity of the emulsified suspension may be high, and the colored resin liquid may not be completely finely dispersed in the aqueous medium. Therefore, it is preferable to further add water. The amount of water added is preferably in the range of 50 to 80% by mass of the amount of water added up to the phase inversion point and the total amount of water used up to the phase inversion point.
Examples of the basic compound used for neutralization include inorganic bases such as sodium hydroxide, potassium hydroxide and ammonia, and organic bases such as diethylamine, triethylamine and isopropylamine. In particular, as the basic compound, it is preferable to use an aqueous solution of an inorganic base such as sodium hydroxide, potassium hydroxide, or ammonia.

  The emulsified suspension produced by the above-described method exists in a state where the colored resin liquid is emulsified in an aqueous medium. The state varies depending on the type of organic solvent, the amount used, the acid value of the binder resin, the amount used of the basic compound, the stirring conditions, etc., but preferably such as resin oil droplets, wax dispersoids, colorant dispersoids, etc. The dispersoid is emulsified as oil droplets having a particle size of less than 1 μm. In such a state, the stability of the emulsified suspension, the unitary stability in the subsequent steps, the particle size distribution of the colored resin fine particles, and the like are improved.

<Third step>
In this step (unification step), by adding an electrolyte, the dispersoid (that is, fine particles composed of the colored resin liquid) is salted out or destabilized, and the dispersoids are integrated with each other. One proceeds to produce coalesced particles.
Examples of the electrolyte used in this step include water-soluble salts such as sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, sodium chloride, potassium chloride, ammonium chloride, calcium chloride, and sodium acetate. Among these, one kind of water-soluble salt or a mixture of two or more kinds of water-soluble salts can be used. In particular, in order to promote uniform coalescence, it is preferable to use a monovalent cation sulfate such as sodium sulfate or ammonium sulfate as the electrolyte.
In addition, since the colored resin fine particles obtained are swollen by a solvent and the hydration state of the particles is unstable due to the addition of an electrolyte, it is preferable that the colored resin fine particles are not broken up. The coalescence proceeds under a low shear force where only one proceeds.

In order to promote uniform coalescence, the agitation conditions for coalescence are important. Specific examples of the stirring blade are an anchor blade, a turbine blade, a fiddler blade, a full zone blade, a max blend blade (registered trademark, manufactured by Sumitomo Heavy Industries, Ltd.), and a half moon blade. Particularly preferred stirring blades are large blades that are excellent in uniform mixing properties even at low rotations, such as Max Blend blades and full zone blades.
A preferable peripheral speed of the stirring blade for generating a uniform unity is 0.2 to 10 m / s, a more preferable peripheral speed is 0.2 to 8 m / s, and a more preferable peripheral speed is 0.2 to 6 m / s.

If the peripheral speed of the stirring blade is higher than 10 m / s, the dispersoid may remain as fine particles. On the other hand, if the peripheral speed is less than 0.2 m / s, the stirring is not uniform, and coalescence may partially progress excessively to generate coarse particles. Under the conditions described above, coalescence proceeds only by collision between the dispersoids, and the dispersoids do not dissociate or disperse. In particular, in the coalescing process, the generation of fine particles is small and a narrow particle size distribution can be obtained.
That is, in the colored resin solution preparation step and the emulsification step, stirring is preferably performed with a high-speed stirrer such as a desper, and in the coalescence step, stirring is preferably performed with a large blade that can be uniformly mixed at a low speed such as a Max blend blade. . Therefore, preferably, the emulsification suspension obtained in the emulsification step is transferred to another container attached to the large blade, and the coalescence step is performed.

Moreover, although the quantity of the electrolyte with respect to solid content is 0.5-15 mass%, it is preferable, it is more preferable that it is 1-12 mass%, and it is further more preferable that it is 1-6 mass%.
When the amount of the electrolyte is less than 0.5% by mass, coalescence does not proceed sufficiently. On the other hand, if it is more than 15% by mass, a large amount of stop water for the subsequent process may be required, and it may take a long time for washing and drying, which may reduce productivity.

Moreover, it is preferable that it is 1-15 mass%, and, as for the density | concentration of electrolyte solution, it is more preferable that it is 3-10 mass%.
When the concentration is less than the lower limit, the effect of the electrolyte is not sufficiently exhibited, and a large amount of electrolyte is required for salting out and coalescence, and coalescence particles may not be sufficiently produced. On the other hand, when the concentration exceeds the upper limit, unevenness is likely to occur in the system, and aggregates are generated during the formation of coalesced particles at the initial stage of coalescence, and as a result, coarse particles are likely to be produced. is there.

In the coalescence process, when the aqueous electrolyte solution is added, it is preferable to increase the stirring speed in order to mix the electrolyte uniformly and quickly in the system.
In the coalescence step, coalescence particles can be generated under relatively low temperature conditions, and the temperature is preferably in the range of 10 to 50 ° C, more preferably in the range of 20 to 40 ° C. More preferably, it is in the range of 20 to 35 ° C.
When this temperature is less than the lower limit, coalescence may not easily proceed. On the other hand, when the temperature exceeds the upper limit, the coalescence speed increases, and aggregates and coarse particles may be easily generated.

  In the coalescing process, the dispersoid swollen by the organic solvent collides, and the dispersoids are fused together to grow particles. Moreover, since particle growth maintains a substantially constant growth rate under a certain condition, it can be expressed by creating a particle growth curve blotted from time and particle size. Therefore, the arrival time of the target particle diameter can be estimated from the curve. As a method for stopping the coalescence, a method of adding water is preferably used.

<4th process>
In this step (separation / drying step), after removing the organic solvent under reduced pressure, the coalesced particles are separated from the aqueous medium, washed, and dried to obtain resin base particles.
The method for removing (desolving) the organic solvent is preferably carried out under reduced pressure because it is carried out rapidly under low temperature conditions.

In removing the solvent, an antifoaming agent is preferably added. As the antifoaming agent, it is preferable to use an antifoaming agent in the form of a silicone emulsion. Examples of the silicone-based antifoaming agent include BY22-517, SH5503, SM5572F, BY28-503 (manufactured by Toray Dow Corning Silicone), KM75, KM89, KM98, KS604, KS538 (Shin-Etsu Chemical Co., Ltd.) ) Made). Among these, as the antifoaming agent, it is preferable to use BY22-517 because it has little influence on physical properties and has a high defoaming effect.
It is preferable that the addition amount of an antifoamer is 30-100 ppm with respect to solid content.

Separation of the resin base particles from the aqueous medium can be performed by a separation means such as a centrifuge, a filter press, a belt filter, or the like.
Drying can be performed by mixing vacuum dryers such as ribocorn dryers (Okawara Seisakusho Co., Ltd.), Nauta mixer (Hosokawa Micron Corp.), fluidized bed dryers (Okawara Seisakusho Co., Ltd.), vibrating fluidized bed dryers (central) It can be carried out using a fluidized bed dryer such as a processing machine.
Note that the organic solvent may not be completely removed and may partially remain in the toner.

  The residual amount of the organic solvent in the finally obtained toner is preferably 5 to 50 ppm, and more preferably 10 to 20 ppm. As described above, since a predetermined amount of the organic solvent remains in the finally obtained toner, the liquid crosslinking force by the silicone oil or the fluorine oil can be made more appropriate. Generation of aggregates can be effectively prevented. As a result, development efficiency and transfer efficiency can be improved, and a uniform image can be formed.

<Fifth step>
In this step (external addition step), an external additive such as silica fine particles and silicone oil and / or fluorine oil are externally added to the obtained resin base particles to obtain the toner of the present invention.
In this step, the resin mother particles and silicone oil or fluorine oil are mixed. The bulk density of the toner obtained can be adjusted by the mixing time of the resin mother particles and silicone oil or fluorine oil. The mixing time is preferably set so that the bulk density of the toner T is 0.25 to 0.35 g / cm ³ .
In addition, the toner as described above may be subjected to various processes such as a classification process and an external addition process as necessary.
For the classification treatment, for example, a sieve, an airflow classifier or the like can be used.

<Image forming apparatus>
Next, an image forming apparatus to which the toner of the present invention as described above is applied will be described.
FIG. 1 is a schematic cross-sectional view showing an example of the overall configuration of an image forming apparatus to which the toner of the present invention is applied.
An image forming apparatus 10 according to this embodiment shown in FIG. 1 records an image on a recording medium mainly by a series of image forming processes including exposure, development, transfer, and fixing. As shown in FIG. 1, such an image forming apparatus 10 has a photosensitive drum (latent image carrier) 20 that carries an electrostatic latent image and rotates in the direction of an arrow in the drawing, and along the rotation direction. A charging unit 30, an exposure unit 40, a developing unit 50, an intermediate transfer member 61, and a cleaning unit 75 are sequentially arranged. In addition, the image forming apparatus 10 is provided with a paper feed tray 82 that accommodates a recording medium P such as paper at the bottom in FIG. The transfer body 61 and the fixing device 90 are sequentially arranged along the conveyance direction of the recording medium P. Further, when forming an image on both sides of the recording medium, the image forming apparatus 10 reverses the recording medium P fixed on one side by the fixing device 90 and returns it to the secondary transfer position described later. The conveyance part 88 for making it do is provided.

The photosensitive drum 20 has a cylindrical conductive substrate (not shown) and a photosensitive layer (not shown) formed on the outer peripheral surface thereof, and can rotate around the axis in the direction of the arrow in FIG. It has become.
The charging unit 30 is a device for uniformly charging the surface of the photosensitive drum 20 by corona charging or the like.
The exposure unit 40 receives image information from a host computer such as a personal computer (not shown), and forms an electrostatic latent image by irradiating the uniformly charged photosensitive drum 20 with a laser. It is a device to do.

  The developing unit 50 includes four developing devices, a black developing device 51, a magenta developing device 52, a cyan developing device 53, and a yellow developing device 54. These developing devices are converted into latent images on the photosensitive drum 20. It is an apparatus that visualizes the latent image as a toner image, selectively used correspondingly. The black developing device 51 uses black (K) toner, the magenta developing device 52 uses magenta (M) toner, the cyan developing device 53 uses cyan (C) toner, and the yellow developing device 54 uses yellow (Y) toner.

  The YMCK developing unit 50 in this embodiment is rotatable so that the above-described four developing devices 51, 52, 53, and 54 are selectively opposed to the photosensitive drum 20. Specifically, in this YMCK developing unit 50, four developing devices 51, 52, 53, and 54 are respectively held by four holding portions 55a, 55b, 55c, and 55d of a holding body 55 that can rotate around a shaft 50a. The four developing devices 51, 52, 53, and 54 are selectively opposed to the photosensitive drum 20 while maintaining the relative positional relationship by the rotation of the holder 55. The developing devices 51, 52, 53, and 54 will be described later in detail.

The intermediate transfer member 61 has an endless belt-like intermediate transfer belt 70, and this intermediate transfer belt 70 is stretched by a primary transfer roller 60, a driven roller 72, and a drive roller 71, and is rotated by the rotation of the drive roller 71. 1 is driven to rotate in the direction of the arrow shown in FIG.
The primary transfer roller 60 is a device for transferring a single color toner image formed on the photosensitive drum 20 to the intermediate transfer belt 70.

  On the intermediate transfer belt 70, a toner image of at least one of black, magenta, cyan, and yellow is carried. For example, when a full-color image is formed, four color toner images of black, magenta, cyan, and yellow are sequentially formed. The toner images are transferred to form a full-color toner image. In the present embodiment, the drive roller 71 also functions as a backup roller for the secondary transfer roller 80 described later. Further, the primary transfer roller 60, the driving roller 71, and the driven roller 72 are supported by the base body 73.

The secondary transfer roller 80 is a device for transferring a single-color or full-color toner image formed on the intermediate transfer belt 70 to a recording medium P such as paper, film, or cloth.
The fixing device 90 is a device for fusing the toner image to the recording medium P and fixing it as a permanent image by heating and pressing the recording medium P that has received the transfer of the toner image.

The cleaning unit 75 has a rubber cleaning blade 76 that contacts the surface of the photosensitive drum 20 between the primary transfer roller 60 and the charging unit 30, and a toner image is transferred onto the intermediate transfer belt 70 by the primary transfer roller 60. Then, the toner remaining on the photosensitive drum 20 is scraped off by the cleaning blade 76 and removed.
The conveyance unit 88 reverses the front and back of the conveyance roller pair 88A and 88B for nipping and conveying the recording medium P fixed on one surface by the fixing device 90 and the conveyance medium pair 88A and 88B. And a conveyance path 88 </ b> C for guiding the registration roller 86. As a result, when an image is formed on both sides of the recording medium, the recording medium P fixed on one side by the fixing device 90 is reversed and returned to the secondary transfer roller 80.

Next, the operation of the image forming apparatus 10 configured as described above will be described.
First, in response to a command from a host computer (not shown), the photosensitive drum 20, the developing roller (not shown) provided in the developing unit 50, and the intermediate transfer belt 70 start to rotate. The photosensitive drum 20 is sequentially charged by the charging unit 30 while rotating.

The charged area of the photosensitive drum 20 reaches an exposure position as the photosensitive drum 20 rotates, and a latent image corresponding to image information of the first color, for example, yellow Y, is formed in the area by the exposure unit 40. .
The latent image formed on the photosensitive drum 20 reaches the developing position as the photosensitive drum 20 rotates, and is developed with yellow toner by the yellow developing device 54. As a result, a yellow toner image is formed on the photosensitive drum 20. At this time, in the YMCK developing unit 50, the yellow developing device 54 faces the photosensitive drum 20 at the developing position.

The yellow toner image formed on the photosensitive drum 20 reaches a primary transfer position (that is, a portion where the photosensitive drum 20 and the primary transfer roller 60 face each other) as the photosensitive drum 20 rotates, and is intermediated by the primary transfer roller 60. Transfer (primary transfer) is performed on the transfer belt 70. At this time, a primary transfer voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner is applied to the primary transfer roller 60. During this time, the secondary transfer roller 80 is separated from the intermediate transfer belt 70.
The same processing as described above is repeatedly executed for the second color, the third color, and the fourth color, so that the toner images of the respective colors corresponding to the respective image signals are transferred onto the intermediate transfer belt 70 in an overlapping manner. The As a result, a full-color toner image is formed on the intermediate transfer belt 70.

On the other hand, the recording medium P is conveyed from the paper feed tray 82 to the secondary transfer roller 80 by the paper feed roller 84 and the registration roller 86.
The full-color toner image formed on the intermediate transfer belt 70 reaches the secondary transfer position (that is, the portion where the secondary transfer roller 80 and the driving roller 71 face each other) as the intermediate transfer belt 70 rotates, and the secondary transfer. The image is transferred (secondary transfer) to the recording medium P by the roller 80. At this time, the secondary transfer roller 80 is pressed against the intermediate transfer belt 70 and a secondary transfer voltage (secondary transfer bias) is applied.

The full-color toner image transferred to the recording medium P is heated and pressurized by the fixing device 90 and fused to the recording medium P. Thereafter, the recording medium P is discharged to the outside of the image forming apparatus 10 by the discharge roller pair 87.
On the other hand, after the primary transfer position has elapsed, the toner adhering to the surface of the photosensitive drum 20 is scraped off by the cleaning blade 76 of the cleaning unit 75 to prepare for charging to form the next latent image. The toner that has been scraped off is collected by a residual toner collecting section in the cleaning unit 75.

  In the case of forming an image on both sides of the recording medium, the recording medium P fixed on one side by the fixing device 90 is once sandwiched between the discharge roller pair 87, and then the discharge roller pair 87 is driven in reverse. By driving the conveyance roller pair 88A, 88B, the recording medium P is turned upside down through the conveyance path 88C and returned to the secondary transfer roller 80, and an image is printed on the other surface of the recording medium P by the same operation as described above. Form.

<Developing device>
Here, based on the drawings, a developing device 54 as an example of a developing device to which the toner of the present invention is applied will be described in detail. The developing devices 51, 52, and 53 are the same as the developing device 54 except that the color of the toner to be used is different, and thus description thereof is omitted.
2 is a perspective view showing a developing device provided in the image forming apparatus shown in FIG. 1, and FIG. 3 is a schematic sectional view showing a schematic configuration of the developing device shown in FIG.
As shown in FIG. 3, the developing device 54 includes a housing 2 in which a toner containing portion 21 that contains toner T (toner of the present invention) that is a developer is formed, a developing roller 3 that carries the toner T, and a developing roller. 3 includes a toner supply roller 4 that supplies the toner T to 3 and a regulating blade 5 that regulates the layer thickness of the toner T carried on the developing roller 3.

The housing 2 stores the toner T in a toner storage portion 21 formed as an internal space thereof.
The housing 2 opens to the right in FIG. 2, and a toner supply roller 4 and a developing roller 3 are rotatably supported in the vicinity of the opening. A regulating blade 5 is attached to the housing 2. Further, a seal member 6 for preventing leakage of toner from between the housing 2 and the developing roller 3 in the opening is attached to the housing 2.

  The developing roller 3 conveys the toner T to a developing position (hereinafter simply referred to as “developing position”) between the developing roller 3 and the photosensitive drum 20 while carrying the toner T on its outer peripheral surface. Further, the developing roller 3 has a cylindrical shape and is rotatable around its axis. In the present embodiment, the developing roller 3 rotates in a direction opposite to the rotation direction of the photosensitive drum 20. Further, as shown in FIG. 2, tape-like spacers 39 are provided on the outer peripheral surfaces of both end portions of the developing roller 3 over the entire periphery. The spacer 39 is pressed against the image non-carrying surface of the photosensitive drum 20 to form a developing gap g between the developing roller 3 and the photosensitive drum 20. The development gap g can be adjusted to a desired size by the thickness of the spacer 39. The constituent material of the spacer 39 is not particularly limited, but it is preferable to use a material having elasticity and higher hygroscopicity than the developing roller 3. The spacer 39 and the developing roller 3 are preferably fixed via an adhesive having elasticity.

  In this way, the developing roller 3 and the photosensitive drum 20 face each other in a non-contact state with a minute gap g. Then, by applying an AC bias (alternating electric field) as a developing bias voltage between the developing roller 3 and the photosensitive drum 20, the toner T is caused to fly from the developing roller 3 to the photosensitive drum 20, and on the photosensitive drum 20. The latent image is developed as a toner image. That is, in this embodiment, so-called non-contact jumping development is performed. In non-contact jumping development, the toner T flies and reciprocates between the developing roller 3 and the photosensitive drum 20 as the AC bias (developing bias voltage) changes.

  In particular, since the toner of the present invention having the above-described conditions is used, the resin base particles become soft agglomerates in the toner container 21 and on the developing roller 3 and behave like a large particle size toner. However, such soft agglomerates are easily crushed by reciprocating between the developing roller 3 and the photosensitive drum 20 during non-contact jumping development. It can behave like a small particle size toner, and as a result, the resolution and gradation of a printed image can be improved. Further, even if toner is sandwiched between the spacer 39 and the photosensitive drum 20, it is difficult to adhere to the spacer 39 and the photosensitive drum 20, so that the development gap g can be maintained for a long time. As a result, a stable image can be formed over a long period of time.

  The toner supply roller 4 supplies the toner T from the toner storage unit 21 via the guide member 7 to the developing roller 3. The toner supply roller 4 includes a main body 41 having a cylindrical shape or a columnar shape, and an elastic porous body layer 42 provided on the main body 41. The elastic porous body layer 42 is made of polyurethane foam or the like, and is in pressure contact with the developing roller 3 while being elastically deformed. In the present embodiment, the toner supply roller 4 rotates in a direction opposite to the rotation direction of the developing roller 3. The toner supply roller 4 has not only a function of supplying the toner T to the developing roller 3 but also a function of peeling off the toner T remaining on the developing roller 3 after the development from the developing roller 3. . Further, a voltage equivalent to the developing bias voltage applied to the developing roller 3 is also applied to the toner supply roller 4.

The regulating blade 5 regulates the layer thickness of the toner T carried on the developing roller 3 and applies a charge to the toner T by frictional charging during the regulation. The regulating blade 5 also functions as a seal member that seals between the housing 2 and the developing roller 3.
The regulating blade 5 includes an elastic body 56 that is abutted along the axial direction of the developing roller 3 and a support member 57 that supports the elastic body 56. The elastic body 56 is made of, for example, silicon rubber, urethane rubber or the like as a main material. The support member 57 is a sheet-like thin plate having a spring property (elasticity) such as phosphor bronze or stainless steel, and has a function of urging the elastic body 56 toward the developing roller 3.
In the present embodiment, the regulating blade 5 is arranged so that the tip (free end) thereof faces the upstream side in the rotation direction of the developing roller 3 and is in a so-called counter contact. Further, the developing device 54 of the present embodiment is configured to drop the excess toner on the developing roller 3 downward by the regulating blade 5 and return it to the toner storage unit 21.

  The toner, the developing device, and the image forming apparatus of the present invention have been described above with respect to the illustrated embodiment. However, the present invention is not limited to this. In addition, each unit constituting the developing device and the image forming apparatus can be replaced with an arbitrary configuration that can exhibit the same function. Moreover, arbitrary components may be added.

Next, specific examples of the present invention will be described.
(Example 1)
<Manufacture of toner>
<Synthesis of binder resin (crosslinked polyester resin)>
Raw materials such as an acid, an alcohol component, and a catalyst having the following composition were put into a 50 liter reaction kettle and reacted at 240 ° C. for 12 hours under a normal pressure nitrogen stream. Thereafter, the pressure was reduced successively and the reaction was continued at 10 mmHg. The reaction was followed by the softening point based on ASTM E28-517, and the reaction was terminated when the softening point reached 160 ° C.

Terephthalic acid 3.9 parts by mass Isophthalic acid 9.06 parts by mass Ethylene glycol 2.54 parts by mass Neopentyl glycol 4.26 parts by mass Tetrabutyl titanate 0.1 parts by mass Epicron 830 0.3 parts by mass (Dainippon Ink and Chemicals, Inc. Bisphenol F type epoxy resin, epoxy equivalent 170 (g / eq)
Cardura E 0.1 parts by mass (Shell Japan alkyl glycidyl ester) epoxy equivalent 250 (g / eq)

The obtained polymer was a colorless solid, and had an acid value of 11.0, a glass transition temperature (Tg) of 60 ° C., and a softening point (T1 / 2) of 178 ° C.
In addition, the weight average molecular weight was determined by using a GPC measuring apparatus (HLC-8120GPC manufactured by Tosoh Corporation) as a separation column in combination with TSK-GEL G5000HXL / G4000HXL / G3000HXL / G2000HXL manufactured by Tosoh Corporation, column temperature: 40 ° C., solvent: tetrahydrofuran, solvent When measured at a concentration of 0.5 mass%, filter: 0.2 μm, flow rate: 1 ml / min and converted using standard polystyrene, the weight average molecular weight was 250,000.

<Synthesis of binder resin (linear polyester resin)>
Raw materials such as an acid, an alcohol component, and a catalyst having the following composition were put into a 50 liter reaction kettle and reacted at 210 ° C. for 12 hours under a normal pressure nitrogen stream. Thereafter, the pressure was reduced successively and the reaction was continued at 10 mmHg. The reaction was followed by the softening point according to ASTM E28-517 and terminated when the softening point reached 87 ° C.

Terephthalic acid 5.31 parts by weight Isophthalic acid 7.97 parts by weight Ethylene glycol 2.6 parts by weight Neopentyl glycol 4.37 parts by weight Tetrabutyl titanate 0.1 part by weight The obtained polymer, that is, a linear polyester resin is It was a colorless solid having an acid value of 10.0, a glass transition temperature (Tg) of 46 ° C, and a softening point (T1 / 2) of 95 ° C.
Further, when the molecular weight was measured in the same manner as the molecular weight measurement of the obtained linear polyester resin, the weight average molecular weight was 5200.

<Preparation of wax master dispersion>
After 30 parts by weight of Carnauba wax (manufactured by Toa Kasei) and 70 parts by weight of the previously prepared linear polyester resin and 150 parts by weight of methyl ethyl ketone were premixed with a desper, Star Mill LMZ-10 (manufactured by Ashizawa Finetech) Refinement | miniaturization was performed and the wax master dispersion 1 with a solid content of 40 mass% was prepared. This composition is linear polyester resin / wax / methyl ethyl ketone = 28/12/60.

<Preparation of colorant master chip>
A ST / AO stirring blade was attached to 2000 parts by mass of cyan pigment (Dai Nippon Ink Chemical Co., Ltd. cyan pigment: Ket Blue111 CI Pigment B-15: 3), 2000 parts by mass of linear polyester resin. The mixture was charged into a 20 L Henschel mixer (Mitsui Mine) and stirred at 698 min ⁻¹ for 2 minutes to obtain a mixture. The mixture was melt-kneaded using an open roll continuous extrusion kneader (Mitsui Mine Needex MOS140-800) to prepare a colorant master chip.
Moreover, when the obtained master chip was diluted with a linear polyester resin and methyl ethyl ketone and observed with a 400 times optical microscope for the finely dispersed state of the colorant and the presence or absence of coarse particles, there was no coarse particles and the fine dispersion was uniform. Was. The composition of the master chip was colorant / resin 2 = 50/50 by mass ratio.

<Colored resin solution preparation process>
Add 10.8 parts by weight of a wax master dispersion, 10.4 parts by weight of a colorant master chip, 12 parts by weight of a crosslinked polyester resin, 10 parts by weight of a linear polyester resin, and 8.65 parts by weight of methyl ethyl ketone. 45 ° C. to the retained and stirrer by (Asada Iron Works, Ltd. Desupa blade diameter 230 mm) were mixed for 2 hours at a stirring rate of 777min ^-1, was dissolved and dispersed.

<Emulsification process>
A cylindrical container equipped with a stirrer having a blade diameter of 230 mm (Desper, manufactured by Asada Iron Works) was charged with 46.37 parts by mass (30 parts by mass of solid content) of the colored resin solution, and then as a basic compound, 1 After adding 5 parts by mass of normal ammonia water and sufficiently stirring at 777 min ⁻¹ , the temperature was adjusted to 35 ° C.
Subsequently, the stirring speed was changed to 1100 min ⁻¹ and 37.25 parts by mass of water was added dropwise at a rate of 1.0 parts by mass / min. The peripheral speed of the stirring blade at this time was 13.2 m / s. As water was added, the viscosity of the system increased, but water was taken into the system at the same time as dropping, and stirring and mixing could be performed uniformly.

  In addition, a phase inversion point at which the viscosity rapidly decreased when 26 parts by mass of water was added was observed. Furthermore, after adding water, when the slurry was observed with an optical microscope, the resin was dissolved, and a state where the colorant dispersoid and the wax dispersoid were dispersed was observed, but no unemulsified material was observed. It was. Since the colorant dispersoid and the wax dispersoid are stably dispersed in the aqueous medium, it is considered that the resin is adsorbed on the surface of the dispersoid. At this time, the state in the system was uniform, and generation of coarse particles due to the addition was not observed.

<Joint process>
After transferring the emulsified suspension obtained in the emulsification step to a cylindrical container provided with a Max Blend blade (registered trademark) having a blade diameter of 340 mm, the temperature was kept at 25 ° C. while maintaining the stirring speed at 85 min ^−1. It was adjusted. Thereafter, the stirring speed was increased to 120 min ⁻¹ , and 12 parts by mass of a 3.5% by mass sodium sulfate aqueous solution was dropped as an electrolyte aqueous solution at a rate of 1 kg / min. Five minutes after the completion of dropping, the stirring speed was reduced to 85 min ⁻¹ and stirring was performed for 5 minutes, and then the stirring speed was reduced to 65 min ⁻¹ and stirring was performed for 5 minutes. Next, the stirring speed was decreased to 47 min ⁻¹ and stirring for 30 minutes was continued. The volume average particle size at this time was 3 μm. Here, the volume average particle diameter Dv was measured with a flow type particle image analyzer (PFIA-2100 manufactured by Sysmex).
<Separation and drying process>
After solid-liquid separation, it was washed with water and dried at 35 ° C. for 7 hours to produce resin mother particles.

<External addition process>
2 parts by weight of negatively chargeable silica silica fine particles RX200 (Nippon Aerosil, average particle size 12 nm, hexamethyldisilazane treatment) and negatively chargeable silica silica fine particles RX50 (Nippon Aerosil, average particle size 40 nm, hexagonal) were added to 100 g of the obtained resin base particles. 1.5 parts by weight of methyldisilazane) was added, and after stirring for 3 minutes at 10,000 rpm with a 1 liter stirrer of 7012S manufactured by COMMERCIAL, dimethyl silicone oil (KF-96 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silicone oil. The toner was prepared by adding 0.5 parts by weight of 200CS) and similarly stirring at 10000 rpm for 1 minute.

(Examples 2 to 5)
A toner was produced in the same manner as in Example 1 except that the amount of silicone oil added was as shown in Table 1.
(Example 6)
A toner was manufactured in the same manner as in Example 1 except that the volume average particle diameter of the resin mother particles was prepared as shown in Table 1.
Here, in this example, the volume average of the resin mother particles as shown in Table 1 is obtained by setting the dropping amount of the 3.5 mass% sodium sulfate aqueous solution (electrolyte solution) to 13 parts by mass in the coalescing step. The particle size was taken.

(Examples 7 and 8)
A toner was produced in the same manner as in Example 1 except that the circularity of the resin mother particles was adjusted as shown in Table 1.
Here, in this example, in the coalescing step, the dropping rate of the sodium sulfate aqueous solution (electrolyte solution) is set to 2.0 kg / min in Example 7, and to 0.5 kg / min in Example 8, The circularity of the resin base particles as shown in Table 1 was used.

(Examples 9 to 13)
A toner was produced in the same manner as in Example 1 except that the drying time in the separation / drying step was as shown in Table 1.
(Examples 14 to 26)
A toner was manufactured in the same manner as in Example 1 except that the silicone oil was changed to perfluoropolyether (BARRIERTA J25V manufactured by NOK Co., Ltd.), which is a fluorine oil.

(Comparative Examples 1 and 2)
An image forming apparatus was produced in the same manner as in Example 1 except that the amount of silicone oil added was as shown in Table 1.
(Comparative Examples 3 and 4)
An image forming apparatus was prepared in the same manner as in Example 1 except that the volume average particle diameter of the resin mother particles was as shown in Table 1.
Here, in the coalescing step, the dropping amount of the 3.5 mass% sodium sulfate aqueous solution (electrolyte solution) is 8 parts by mass in Comparative Example 3 and 16 parts by mass in Comparative Example 4, so that Table 1 It was set as the volume average particle diameter of the resin mother particle as shown.

(Comparative Example 5)
A toner was produced in the same manner as in Example 1 except that the circularity of the resin mother particles was adjusted as shown in Table 1.
Here, in this example, in the coalescing step, the dropping rate of the sodium sulfate aqueous solution (electrolyte solution) was set to 3.0 kg / min, so that the circularity of the resin mother particles as shown in Table 1 was obtained.
For each of the above Examples and Comparative Examples, the drying time in the separation / drying process, the volume average particle diameter Dv of the resin mother particles, the volume average particle diameter Dv / number average particle diameter Dn, the average circularity of the resin mother particles, the resin Table 1 shows the bulk density of the base particles, the addition amount of silicone oil or fluorine oil, and the residual amount of methyl ethyl ketone.

<Evaluation>
Evaluation is performed by the following evaluation test method, and the results are shown in Table 1.
<Development unevenness>
An image of 30% solid density was formed on A3 size electrophotographic plain paper, and the OD values at 20 arbitrary locations were measured, and the average of the OD values with respect to the maximum OD value was expressed as 100 minutes.
<Development efficiency>
Adhere the adhesive tape to the photosensitive drum and the developing roller respectively, measure the amount of toner stuck to each adhesive tape, and find the development efficiency = (toner amount on the photoconductor) / (toner amount on the developing roller). It was.

<Resolution>
A negative image composed of 40 μm lines was printed on electrophotographic plain paper, the image reproducibility was observed with a microscope, and evaluated according to the following three criteria.
○: The 40 μm line was faithfully reproduced.
X: The line of 40 μm was not reproduced, and interruption or weighting occurred in the middle of the line.
These results are shown in Table 1 together.

As is apparent from Table 1, in each of the examples according to the present invention, the line reproducibility was excellent (that is, high resolution), the development efficiency was high, and the development unevenness could be suppressed to a low level. In particular, in Examples 1 to 4, 6, 13 to 16, and 18, the development efficiency was extremely high, and development unevenness could be suppressed to a very low level.
On the other hand, each comparative example was inferior to each example. In particular, Comparative Examples 1, 4, and 5 had poor line reproducibility, and Comparative Examples 2 and 3 had poor development efficiency.

1 is a schematic cross-sectional view illustrating an example of an overall configuration of an image forming apparatus to which a toner of the present invention is applied. FIG. 2 is a perspective view illustrating a developing device provided in the image forming apparatus illustrated in FIG. 1. FIG. 3 is a schematic cross-sectional view showing a schematic configuration of the developing device shown in FIG. 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 3 ... Developing roller 6 ... Sealing member 2 ... Housing 21 ... Toner accommodating part 4 ... Toner supply roller 5 ... Restricting blade 56 ... Elastic body 57 ... Supporting member 20 ... Photosensitive drum 30 ... Charging unit 39 ... Spacer 40 ... Exposure unit 41 ... Main body 42 ... Elastic porous body layer 50 ... Developing unit 50a ... Shaft 51 ... Black developing device 52 ... Magenta developing device 53 ... Cyan developing device 54 ... Yellow developing device 55 ... Holding body 55a-55d ... Holding unit DESCRIPTION OF SYMBOLS 60 ... Primary transfer roller 61 ... Intermediate transfer body 70 ... Intermediate transfer belt 71 ... Drive roller 72 ... Drive roller 73 ... Substrate 75 ... Cleaning unit 76 ... Cleaning blade 80 ... Secondary transfer roller 82 ... Paper feed tray 84 ... Paper feed roller 86 ... Registration roller 87 ... Discharge roller pair 88 ... Conveying section 88A, 88B ... Conveying roller pair 88C ... Conveying path 90 ... Fixing device P ... Recording medium T ... Toner

Claims (8)

Resin mother particles composed of a colorant and a binder resin;
Silicone oil and / or fluorine oil,
The volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin base particles represented by the following formula (I) is 0.97 to 0.99,
The toner according to claim 1, wherein the silicone oil and / or fluorine oil is added to the resin base particles in an amount of 0.05 to 2% by mass.
R = L ₀ / L ₁ (I)
(Wherein, L 1 _[μm] is a circumferential length of a projected image of the measuring object resin base particles, L 0 _[μm] is a perfect circle having the same area as the projected image of the resin base particles to be measured Represents the perimeter of   The toner according to claim 1, wherein Dv / Dn is 1 to 1.1, where Dv is a volume average particle diameter of the toner and Dn is a number average particle diameter of the toner. The bulk density of the resin base ^particles, toner according to claim 1 or 2 is ^{0.25g / cm 3 ~0.35g / cm 3} .   The toner according to claim 1, comprising inorganic fine particles as an external additive. A first step of obtaining a colored resin liquid by dissolving or dispersing at least a binder resin and a colorant in an organic solvent;
A second step of obtaining an emulsified suspension obtained by emulsifying the colored resin liquid in an aqueous medium by sequentially adding a basic compound and water to the colored resin liquid;
A third step of coalescing the dispersoid in the emulsion suspension by adding an aqueous electrolyte solution to the emulsion suspension to obtain coalesced particles;
After removing the organic solvent, the coalesced particles are separated from the aqueous medium, washed, and dried to obtain the resin mother particles;
The toner according to any one of claims 1 to 4, wherein the toner is produced using a method having a fifth step of adding the silicone oil or fluorine oil to the obtained resin base particles.   The toner according to claim 5, wherein the remaining amount of the organic solvent is 5 to 50 ppm. A toner container for containing toner;
A developing roller having a function of carrying the toner on the outer peripheral surface;
The toner includes resin base particles including a colorant and a binder resin;
Silicone oil and / or fluorine oil,
The volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin base particles represented by the following formula (I) is 0.97 to 0.99,
The developing device according to claim 1, wherein the addition amount of the silicone oil and / or fluorine oil to the resin base particles is 0.05 to 2% by mass. A latent image carrier for carrying a latent image;
A developing device that visualizes the latent image as a toner image by applying toner to the latent image carrier;
The developing device includes a toner storage unit that stores toner;
A developing roller having a function of carrying the toner on the outer peripheral surface thereof, facing the latent image carrier in the vicinity.
The toner includes resin base particles including a colorant and a binder resin;
Silicone oil and / or fluorine oil,
The volume average particle diameter of the resin base particles is 2 to 4 μm, and the circularity of the resin base particles represented by the following formula (I) is 0.97 to 0.99,
An image forming apparatus, wherein an addition amount of the silicone oil and / or fluorine oil to the resin base particles is 0.05 to 2% by mass.

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