WO2015029843A1

WO2015029843A1 - Toner, developer, and image forming apparatus

Info

Publication number: WO2015029843A1
Application number: PCT/JP2014/071691
Authority: WO
Inventors: Yoshihiro Moriya; Ryota Inoue; Tatsuru Moritani; Tatsuki YAMAGUCHI
Original assignee: Ricoh Company, Ltd.
Priority date: 2013-08-28
Filing date: 2014-08-13
Publication date: 2015-03-05
Also published as: JP2015172721A

Abstract

A toner containing at least a binder resin and a releasing agent, wherein the maximum length Lmax of the releasing agent in a toner particle is 1.1 or greater times as large as the maximum Feret diameter Df of the toner particle containing the releasing agent.

Description

DESCRIPTION

Title of Invention

TONER, DEVELOPER, AND IMAGE FORMING APPARATUS

Technical Field

The present invention relates to a toner used in

electrophotography, electrostatic recording, electrostatic printing, etc.

Background Art

Toners used in electrophotography, electrostatic recording, electrostatic printing, etc. are temporarily deposited on an image bearing member such as an electrostatic latent image bearing member on which an electrostatic charge image is formed in a toner development step, then transferred from the electrostatic latent image bearing member onto a transfer medium such as a transfer sheet in a transfer step, and after this, fixed on the sheet in a fixing step. As the fixing method, a method of fixing the toner by means of contact heating melting using a heated roll, belt, or the like is commonly used, because this method is thermally efficient.

However, the contact heating fixing method has a problem that it tends to cause offset, in which the melted toner adheres to the heat roll or the belt.

To prevent the offset, there are proposed some methods to add a releasing agent such as a wax to the toner. One of them proposes a toner that contains a wax having a specific differential scanning calorimetry (DSC) endothermic peak (PTL l). Another of them proposes use of a candelilla wax, a higher fatty acid-based wax, a higher

alcohol-based wax, a plant-based natural wax (a carnauba wax, and a rice wax), a montan-based ester wax, etc. as the releasing agent (PTL 2).

When the toner passes the heated roll or a belt member in the contact heating fixing method, these releasing agents smoothly melt and get exposed on the surface of the toner particles, to thereby suppress the melted toner from adhering to the fixing members. Releasing agents are influential not only to offset at low fixing temperatures (cold offset), but also to offset at high fixing temperatures (hot offset).

On the other hand, when a releasing agent is located about the surface of a toner in order to be smoothly exposed from the toner, offset is suppressed, but likelihood of occurrence of melt adhesion based on the releasing agent increases during stirring in a developing device, which makes it likely for filming, in which the toner adheres to a carrier or a photoconductor in a crushed state to degrade the development, to occur.

That is, it is necessary for the releasing agent to be present and protected inside the toner during stirring and storage, and to be exposed on the surface effectively in a short time in which the toner is passing the fixing member during fixing.

For this problem, there are many reports on experiments for prescribing the dispersed particle diameter of a wax as a releasing agent, as seen in PTL 3. Prescribing the dispersed particle diameter is effective in maintaining toner granulation performance, and preventing offset at the same time. However, when a wax is introduced into a toner in a dispersed state, it typically cannot avoid being more minute than the toner particle diameter. It is very difficult to retain such a minute wax selectively in the vicinity of the surface without getting it exposed on the surface.

Further, in order for an offset resisting property to be expressed, it is more effective for the releasing agent to be present in the toner as a relatively large agglomerate, than for it to be present in the toner locally as a minute domain. However, when the additive amount of the releasing agent is increased in order to enlarge the domain, the strength of the toner on the whole is weakened, which makes the toner more crushable and degrades the filming resistance to the contrary.

PTL 4 describes that a toner that is excellent in filming property with respect to a photoconductor, etc., offset resistance, and low temperature fixability can be obtained by dispersing a releasing agent having a specific shape property in the toner. However, this toner still needs improvement in order to satisfy filming resistance and offset resistance at the same time.

That is, the conventional techniques are unsatisfactory in satisfying filming resistance and offset resistance at the same time effectively with a small additive amount of a releasing agent, and further improvement is currently being needed.

Citation List

Patent Literature

PTL 1 Japanese Patent Application Laid pen (JP-A) No. 07-84401

PTL 2 JP-A No. 05-341577

PTL 3 JP-A No. 2009-134061

PTL JP-A No. 2009-294492

Summary of Invention

Technical Problem

The present invention was made in view of such a circumstance, and an object of the present invention is to provide a toner excellent in offset resistance and filming resistance and capable of providing highly-precise high-quality images for a long time, a developer, and a toner producing method, by providing a toner containing a releasing agent that is located in such a state as not to spoil toner strength and realizes effective exuding during fixing.

Solution to Problem

As the result of conducting earnest studies, the present inventors have discovered that the problems described above can be solved with a toner that contains at least a binder resin and a releasing agent, and in which the maximum length Lmax of the releasing agent in a toner particle is 1.1 or greater times as large as the maximum Feret diameter Df of the toner particle, and have completed the present invention.

Means for solving the problems described above is as follows.

A toner, including at least:

a binder resin, and a releasing agent,

wherein a maximum length Lmax of the releasing agent in a toner particle is 1.1 or greater times as large as a maximum Feret diameter Df of the toner particle containing the releasing agent.

Advantageous Effects of Invention

The present invention can provide a toner excellent in offset resistance and filming resistance and capable of providing highly-precise high-quality images for a long time.

Brief Description of Drawings

Fig. 1 is a diagram showing a method for measuring a maximum Feret diameter Df of a toner of the present invention and a maximum length Lmax of a releasing agent.

Fig. 2A is a diagram showing an example of a TEM image of a cross -section of a toner of the present invention.

Fig. 2B is a diagram showing an example of a TEM image of a cross-section of a toner of the present invention.

Fig. 3 is a cross -sectional diagram showing a configuration of a liquid column resonance liquid droplet forming unit.

Fig. 4 is a cross-sectional diagram showing a configuration of a liquid column resonance liquid droplet unit.

Fig. 5A is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is fixed at one end and N=l. Fig. 5B is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is fixed at both ends and N=2.

Fig. 5C is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is free at both ends and N=2.

Fig. 5D is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is fixed at one end and N=3.

Fig. 6A is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is fixed at both ends and N=4.

Fig. 6B is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is free at both ends and N=4.

Fig. 6C is a schematic explanatory diagram showing a standing wave of velocity and pressure pulsation when a liquid column resonance liquid chamber is fixed at one end and N=5.

Fig. 7A is a schematic explanatory diagram showing a liquid column resonance phenomenon arising in a liquid column resonance flow path of a liquid column resonance liquid droplet forming unit.

Fig. 7B is a schematic explanatory diagram showing a liquid column resonance phenomenon arising in a liquid column resonance flow path of a liquid column resonance liquid droplet forming unit.

Fig. 7C is a schematic explanatory diagram showing a liquid column resonance phenomenon arising in a liquid column resonance flow path of a liquid column resonance liquid droplet forming unit.

Fig. 7D is a schematic explanatory diagram showing a liquid column resonance phenomenon arising in a liquid column resonance flow path of a liquid column resonance liquid droplet forming unit.

Fig. 8 is a schematic diagram of a toner producing apparatus.

Fig. 9 is a cross-sectional diagram showing a configuration of a liquid column resonance liquid droplet forming unit.

Description of Embodiments

The present invention will be described below in detail.

A toner of the present invention is a toner containing at least a binder resin and a releasing agent, and characterized in that a maximum length Lmax of the releasing agent in a toner particle is 1.1 or greater times as large as a maximum Feret diameter Df of the toner particle containing the releasing agent.

The maximum length Lmax of the releasing agent in the toner particles and the maximum Feret diameter Df of the toner particles can be determined based on a transmission electron microscope (TEM) image of a torn surface of the toner particles.

As a TEM observation, for example, the toner is embedded in an epoxy resin, and sliced with an ultramicrotome (ultrasonic) to be made into a thin toner piece, which is used for observation of torn surfaces of toner particles with a transmission electron microscope. The

magnification of the microscope is adjusted such that the viewing field of the microscope is enlarged to the extent that the maximum Feret diameter and Lmax can be measured from the torn surfaces of toner particles. In this way, arbitrary 50 torn surfaces of toner particles are extracted as measurement samples. After the extraction, image files of the samples are processed with image analysis software IMAGEJ so that Lmax and Df of each sample may be obtained.

Here, Lmax represents the maximum releasing agent length that is included in a torn surface of a toner particle.

In the toner of the present invention, an average of values

[Lmax/Df] calculated for each of the 50 sample torn surfaces is 1.1 or greater.

Fig. 2A shows a representative cross-sectional view of the toner. Lmax is obtained by staining the toner with ruthenium/osmium to adjust the contrast and emphasize the releasing agent in the toner. With multi-point selection of the IMAGEJ, a plotting line is drawn so as to run the center within the releasing agent image, and the sum total of the distances between the plotting points is calculated as the releasing agent length.

Fig. 2B shows the image of Fig. 2A that results from plotting, with inversion to emphasize the wax. The image may be binarized according to necessity. An image processing technique may be appropriately selected in order to enable the wax's state of being to be observed. Fig. 2B shows plotting from 1 to 38.

It is necessary that the maximum length Lmax of the releasing agent in a toner particle be 1.1 or greater times as large as the maximum Feret diameter Df of the toner particle containing the releasing agent. When the maximum length Lmax is less than 1.1 times as large as Df, both ends of the releasing agent that is present locally within the toner cannot reach the toner surface, and may not hardly exude during the fixing, which may result in a poor offset property.

Particularly, the maximum length Lmax is more preferably from 1.2 to 1.6 times as large as the maximum Feret diameter Df of the toner particle containing the releasing agent.

Fig. 1 shows a method for measuring a maximum Feret diameter Df of the toner of the present invention and the maximum length Lmax of the releasing agent.

As shown in Fig. 1, the maximum Feret diameter Df of a toner particle 1001 is the distance between the largest-distanced two parallel tangent lines, of a plurality of pairs of two parallel tangent lines that are drawn to contact the points on respective pairs of opposite sides on the circumference of the toner torn surface of the TEM image. The maximum length Lmax of a releasing agent 1002 represents the length of the distance between opposite ends of the releasing agent, the distance between which is the largest of the distances between all such opposite ends in one toner particle.

The releasing agent of the present invention is a wax. The content of the wax, as a mass equivalent of an endothermic amount of the wax obtained according to a DSC (differential scanning calorimetry) procedure, is preferably from 1% by mass to 20% by mass relative to the whole toner. Further, the amount of the wax that is present in a region down to the depth of 0.3 μπι from the surface of the toner, which is obtained according to a FTIR ATR (total reflection and infrared

absorption spectroscopy) procedure, is preferably 0.1% by mass or greater but less than 4% by mass.

A method for measuring the ratio of the content of the wax will be explained in detail below.

The total amount of the wax in a toner particle is obtained according to a DSC (differential scanning calorimetry) procedure. A toner sample and a wax-only sample are separately measured with the measuring instrument below and under conditions below, and the total amount of the wax is calculated from the ratio between the endothermic amounts of the wax measured from these samples respectively.

■Measuring instrument-^' a DSC instrument (DSC60 manufactured by Shimadzu Corporation)

-Amount of sample: about 5 mg

-Temperature raising rate^ 10°C/min

-Range of measurement-^' from room temperature to 150°C

-Measurement atmosphere: nitrogen gas atmosphere

The total amount of the wax is calculated according to the formula A below.

Total amount of wax (% by mass) = ((Endothermic amount (J/g) of the wax in the toner sample) l00) / (Endothermic amount (J/g) of the wax-only) ---(Formula A)

This analysis enables effective prescription of the total amount of the wax in a toner particle, even when not the whole of the added wax is compounded in the toner because of leakage of the wax during the toner production process.

The amount of the wax at the surface of a toner particle is obtained according to a FTIR-ATR (total reflection and infrared

absorption spectroscopy) procedure. By the principle of the

measurement, the depth of analysis is about 0.3 μιη. Through this analysis, the amount of the wax in a region down to the depth of 0.3 μιη from the surface of a toner particle can be obtained. The measurement procedure is as follows.

^■First, as a sample, a toner (3 g) is made into a pellet having a size of 40 mmij) (a thickness of about 2 mm) with pressing by an automatic pellet molder (Type M No. 50BRP-E manufactured by MAEKAWA

TESTING MACHINE CO.) under a load of 6 t for 1 minute.

-The surface of this toner pellet is measured according to a

FTIR-ATR procedure.

The microscopic FTIR instrument used is SPECTRUM ONE manufactured by PERKIN ELMER Co., Ltd. equipped with a

MULTISCOPE FTIR unit. This instrument performs measurement by micro ATR of a germanium (Ge) crystal having a diameter of 100 μπι.

-Measurement is performed 20 times cumulatively at an infrared incidence angle of 41.5° at a resolution of 4 cm ¹.

The ratio of intensity between the obtained peaks attributed to the wax and to the binder resin is regarded as a relative amount of the wax at the surface of a toner particle. An average of four such

measurements performed at different measurement positions is used as this relative value.

-The amount of the wax at the surface of the sample is calculated based on a relation with a relative amount of a wax in a sample for a calibration curve in which a known amount of a wax is dispersed uniformly.

Note that, the wax that is present in a region down to a depth of 0.3 μηι from the surface of a toner particle, which is analyzed by the FTIR-ATR procedure, exerts the toner releasing function effectively, because the wax in this region is located at a position at which it can exude onto the surface of the toner easily.

The amount of the wax at the surface of a toner particle, which is obtained according to the FTIR-ATR procedure, is preferably 0.1% by mass or greater but less than 4% by mass. As long as the amount of the wax at the surface is 0.1% by mass or greater, the amount of the wax in the vicinity of the surface of a toner particle is not to be scarce, and sufficient releasability can be obtained hence during fixing. As long as the amount of the wax at the surface is less than 4% by mass, the amount of the wax in the vicinity of the surface of a toner particle is not to be too large, which prevents the wax from being exposed onto the outermost surface of the toner particle, and prevents degradation of filming resistance of a developer, which is due to increase of chances of adhesion to a carrier surface via the wax. The amount of the wax at the surface is more preferably from 0.1% by mass to 3% by mass, in order for offset resistance during fixing, chargeability, developability, filming resistance, etc. to be satisfied at the same time more favorably. The total amount of the wax obtained according to a DSC

procedure is preferably from 1% by mass to 20% by mass in a toner particle. As long as the total amount of the wax is 1% by mass or greater, the amount of the wax contained in a toner particle is not to be scarce, which secures sufficient releasability during fixing and prevents

degradation of offset resistance. As long as the total amount of the wax is 20% by mass or less, filming resistance and glossiness of a color image after fixing may not degrade, which is preferable.

Constituent materials of the toner are not particularly limited, as long as the toner can satisfy the above properties. However, a specific constitution will be described below as an example.

-Toner Composition-

The toner of the present invention contains at least a binder resin and a releasing agent, and further contains other components such as a colorant, a pigment dispersant, and a charge controlling agent according to necessity. Any other toner materials may be the same as those used in the conventional toners. Furthermore, a flowability improver, a cleanability improver, etc. may be added to the surface according to the necessity to obtain a toner.

These constituent materials will be described below in detail as a toner composition.

•-Binder Resin- -

The binder resin is not particularly limited as long as it can dissolve in an organic solvent to be used, and a commonly used resin may be appropriately selected and used as the binder resin. Examples of the binder resin include: a vinyl polymer of a styrene-based monomer, an acrylic-based monomer, a methacrylic-based monomer, or the like; a copolymer of these monomers or two or more kinds; a polyester-based polymer; a polyol resin; a phenol resin; a silicone resin; a polyurethane resin; a polyamide resin,^' a furan resin; an epoxy resin; a xylene resin; a terpene resin; a coumarone-indene resin; a polycarbonate resin; and a petroleum-based resin.

The styrene-based monomer is not particularly limited and an appropriate one may be selected according to the purpose. Examples thereof include^ styrenes such as styrene, o-methyl styrene, nrmethyl styrene, p-methyl styrene, p-phenyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, p-n-amyl styrene, p-tert'butyl styrene, p-n-hexyl styrene, p-n-octyl styrene, p-n-nonyl styrene, p-n-decyl styrene, p-n-dodecyl styrene, p-methoxy styrene, p-chloro styrene, 3,4-dichloro styrene, n nitro styrene, o-nitro styrene, and p-nitro styrene; and derivatives thereof.

The acrylic-based monomer is not particularly limited and an appropriate one may be selected according to the purpose. Examples thereof include acrylic acid and acrylic acid ester. The acrylic acid ester is not particularly limited and an appropriate one may be selected according to the purpose. Examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, n-dodecyl acrylate, 2-ethyl hexyl acrylate, stearyl acrylate,

2-chloroethyl acrylate, and phenyl acrylate.

The methacrylic-based monomer is not particularly limited and an appropriate one may be selected according to the purpose. Examples thereof include methacrylic acid and methacrylic acid ester. The methacrylic acid ester is not particularly limited and an appropriate one may be selected according to the purpose. Examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, n-dodecyl methacrylate, 2-ethyl hexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethyl amino ethyl methacrylate, and diethyl amino ethyl methacrylate.

Any other monomer, with which the vinyl polymer or the copolymer is made is not particularly limited, and an appropriate one may be selected according to the purpose. Examples thereof include (l) to (18) below.

(1) Monoolefins such as ethylene, propylene, butylene, and isobutylene

(2) Polyenes such as butadiene and isoprene

(3) Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride

(4) Vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate

(5) Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether

(6) Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone

(7) N-vinyl compounds such as N-vinyl pyrrol, N-vinyl carbazole, N-vinyl indole, and N-vinyl pyrrolidone

(8) Vinyl naphthalines

(9) Derivatives of acrylic acid or methacrylic acid such as acrylonitrile, methacrylonitrile, and acrylamide

(10) Unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenylsuccinic acid, fumaric acid, and mesaconic acid

(11) Unsaturated dibasic acid anhydrides such as maleic

anhydride, citraconic anhydride, itaconic anhydride, and alkenylsuccinic anhydride

(12) Unsaturated dibasic acid monoesters such as maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid monobutyl ester, citraconic acid monomethyl ester, citraconic acid monoethyl ester, citraconic acid monobutyl ester, itaconic acid monomethyl ester, alkenylsuccinic acid monomethyl ester, fumaric acid monomethyl ester, and mesaconic acid monomethyl ester

(13) Unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid

(14) α,β-unsaturated acids such as crotonic acid and cinnamic acid

(15) ,β-unsaturated acid anhydrides such as crotonic anhydride and cinnamic anhydride

(16) Anhydrides of any α,β-unsaturated acid above with lower fatty acid, alkenyl malonic acid, alkenyl glutaric acid, alkenyl adipic acid, and monomers having a carboxyl group such as anhydrides and

monoesters of these acids

(17) Acrylic acid or methacrylic acid hydroxyalkyl esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and

2-hydroxypropyl methacrylate

(18) Styrene monomers having a hydroxy group, such as

4-(l-hydroxy-l-methylbutyl)styrene, and

4- ( 1^■ hydroxy - 1 - methy lhexy 1) sty re ne

In the toner according to the present invention, the vinyl polymer or the copolymer as the binder resin may contain a cross-linked structure produced by a cross-linking agent having 2 or more vinyl groups.

The cross-linking agent is not particularly limited, and an appropriate one may be selected according to the purpose. Examples thereof include- aromatic divinyl compounds such as divinyl benzene and divinyl naphthalene; diacrylate compounds linked with an alkyl chain, such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate,

1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and products obtained by substituting methacrylate for the acrylate of these compounds,^' and diacrylate compounds linked with an alkyl chain having an ether bond, such as diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #400 diacrylate, polyethylene glycol #600 diacrylate, dipropylene glycol diacrylate, and products obtained by substituting methacrylate for the acrylate of these compounds.

Other examples include diacrylate compounds and dimethacrylate compounds linked with a chain having an aromatic group and an ether bond. Further, examples of the cross-linking agent include

polyester-based diacrylates such as MANDA (product of Nippon Kayaku Co., Ltd.).

Furthermore, examples of the cross-linking agent include multifunctional cross- linking agents such as pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate,

tetramethylolmethane tetraacrylate, oligoester acrylate, products obtained by substituting methacrylate for the acrylate of these compounds, triallyl cyanurate, and triallyl trimellitate.

Among these cross-linking agents, the aromatic divinyl compounds (particularly, divinyl benzene) and the diacrylate compounds linked with a chain having one aromatic group and one ether bond are preferable in terms of fixability in the toner resin, and offset resistance. Among these, combinations of monomers that will make a styrene-based copolymer or a styrene/acrylic-based copolymer are preferable.

Examples of a polymerization initiator used for production of the vinyl polymer or the copolymer of the present invention include^

2,2'-azobisisobutyronitrile,

2,2'- azobis(4-methoxy- 2, 4" dime thy lvaleronitrile) ,

2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobisisobutyrate, l,l'-azobis(l-cyclohexanecarbonitrile), 2-(carbamoylazo)-isobutyronitrile, 2,2'-azobis(2,4,4-trimethylpentane), 2-phenylazo-2',4'-dimethyl-4'-methoxyvaleronitrile,

2,2'-azobis(2-methylpropane), ketone peroxides (e.g., methyl ethyl ketone peroxide, acetyl acetone peroxide, and cyclohexanone peroxide), 2.2- bis(tert-butylperoxy)b tane, tert-butylhydroperoxide, cumenehydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide,

di'tert-butylperoxide, tert-butylcumylperoxide, dicumylperoxide, a-(tert"butylperoxy)isopropylbenzene, isobutylperoxide, octanoylperoxide, decanoylperoxide, lauroylperoxide, 3,5,5-trimethylhexanoylperoxide, benzoylperoxide, nrtolylperoxide, di'isopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-n-propylperoxydicarbonate, di-2-ethoxyethylperoxycarbonate, drethoxyisopropylperoxydicarbonate, di(3 - methyl- 3 - methoxybuty peroxy carbonate ,

acetylcyclohexylsulfonylperoxide, tert-butylperoxyacetate,

tert-butylperoxyisobutyrate, tert-butylperoxy-2-ethylhexarate,

tert-butylperoxylaurate, tert-butyl-oxybenzoate,

tert-butylperoxyisopropylcarbonate, di'tert-butylperoxyisophthalate, tert-butylperoxyallylcarbonate, isoamylperoxy-2-ethylhexanoate, drtert-butylperoxyhexahydroterephthalate, and tert-butylperoxyazelate.

When the binder resin is a styrene/acrylic-based resin, it is preferable that the binder resin have at least one peak in a molecular weight range of from 3,000 to 50,000 (on a number average molecular weight basis) in a molecular weight distribution obtained by GPC of a tetrahydrofuran (THF) soluble content of the resin component.

Examples of a constituent monomer of the polyester-based polymer include the followings.

Examples of dihydric alcohol as the constituent monomer include: ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol,

2.3- butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and 2-ethyl-l,3"hexanediol; bisphenol A, and diol obtained by polymerizing bisphenol A with cyclic ether such as ethylene oxide and propylene oxide.

Use of trihydric or higher polyhydric alcohol and trivalent or higher acid in combination allows the polyester-based polymer to undergo cross -linking. However, the amount of use thereof needs to be in a range in which the resin is not hindered from dissolving in an organic solvent.

Examples of the trihydric or higher polyhydric alcohol include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol,

dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl- 1,2,4-butanetriol,

trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxybenzene.

Examples of a constituent acid component of the polyester-based polymer include : benzenedicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, or anhydrides thereof;

alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, or anhydrides thereof; unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenylsuccinic acid, fumaric acid, and mesaconic acid; and unsaturated dibasic acid anhydrides such as maleic anhydride, citraconic anhydride, itaconic anhydride, and alke ny Is uccinic anhydride .

Examples of trivalent or higher polyvalent carboxylic acid components include trimellitic acid, pyromellitic acid,

1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid,

2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid,

l,3-dicarboxy-2-methyl-methylenecarboxypropane,

tetra(methylenecarboxy)methane, 1,2,7,8-octanetetracarboxylic acid, and enpol trimer acid, or anhydrides and partially lower alkyl esters thereof.

When the binder resin is the polyester-based resin, it is preferable that the binder resin have at least one peak in a molecular weight range of from 3,000 to 50,000 in a molecular weight distribution of a THF soluble content of the resin component, in terms of toner fixability and offset resistance. Further, it is preferable that the binder resin have a THF soluble content of which components having a molecular weight of 100,000 or less account for 70% to 100%, in terms of dischargeability . Furthermore, it is more preferable that the binder resin have at least one peak in a molecular weight range of from 5,000 to 20,000.

In the present invention, a molecular weight distribution of the binder resin is measured by gel permeation chromatography (GPC) using THF as a solvent.

When the binder resin is the polyester-based polymer, the acid value thereof is preferably from 0.1 mgKOH/g to 100 mgKOH/g. It is more preferably from 0.1 mgKOH/g to 70 mgKOH/g, and particularly preferably from 0.1 mgKOH/g to 50 mgKOH/g.

In the present invention, the acid value of the binder resin component of the toner composition is measured according to the procedure below, of which basic operation is based on JIS ΚΌ070.

(l) The sample to be used is previously rid of additives other than the binder resin (polymer component), or alternatively the acid values and the contents of the components of the sample other than the binder resin and a cross-linked binder resin are previously obtained. A pulverized product of the sample is weighed out precisely in an amount of from 0.5 g to 2.0 g. The weight of the polymer component is expressed as Wg. For example, when measuring the acid value of the binder resin from a toner, the acid value and content of a colorant, a magnetic material, or the like are previously measured, and the acid value of the binder resin is obtained by calculation.

(2) The sample is put in a 300 ml beaker, to which a mixture liquid of toluene/ethanol (at a volume ratio of 4/1) (150 ml) is added to dissolve the sample.

(3) Titration is performed with a potentiometric titrator using a

0.1 mol/1 ethanol solution of KOH.

(4) The amount of the KOH solution used in the above is S (ml). At the same time, a blank sample is measured, and the amount of the

KOH solution used for this is B (ml). The acid value is calculated according to the formula (C) below, where f represents the factor of KOH.

Acid value (mgKOH/g) = [(S-B)xfx5.61]/W -Formula (C)

The glass transition temperature (Tg) of the binder resin of the toner and the composition containing the binder resin is preferably from

35°C to 80°C, and more preferably from 40°C to 70°C, in terms of toner storage stability.

When the glass transition temperature (Tg) is lower than 35°C, the toner may be susceptible to deterioration under a high-temperature atmosphere. When the glass transition temperature (Tg) is higher than 80°C, fixability may be poor.

The binder resin to be used may be appropriately selected from those listed above depending on an organic solvent and a releasing agent to be used. Use of a releasing agent having excellent solubility to an organic solvent may lower the softening point of the toner. In such a case, it is effective to raise the softening point of the binder resin by increasing the weight average molecular weight of the binder resin, in order to maintain a favorable hot offset property.

"Colorant"

The colorant is not particularly limited, and an appropriate one may be selected from commonly used colorants. Examples thereof include carbon black, a nigrosine dye, iron black, naphthol yellow S,

Hansa yellow (10G, 5G and G), cadmium yellow, yellow iron oxide, yellow ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN and R), pigment yellow L, benzidine yellow (G and GR), permanent yellow (NCG), vulcan fast yellow (5G, R), tartrazinelake, quinoline yellow lake, anthrasan yellow BGL, isoindolinon yellow, colcothar, red lead, lead vermilion, cadmium red, cadmium mercury red, antimony vermilion, permanent red 4R, parared, riser red,

parachloroorthonitro anilin red, lithol fast scarlet G, brilliant fast scarlet, brilliant carmine BS, permanent red (F2R, F4R, FRL, FRLL and F4RH), fast scarlet VD, vulcan fast rubin B, brilliant scarlet G, lithol rubin GX, permanent red F5R, brilliant carmine 6B, pigment scarlet 3B, Bordeaux

5B, toluidine Maroon, permanent Bordeaux F2K, Helio Bordeaux BL,

Bordeaux 10B, BON maroon light, BON maroon medium, eosin lake, rhodamine lake B, rhodamine lake Y, alizarin lake, thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS and BC), indigo, ultramarine, iron blue,

anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese violet, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, viridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc flower, lithopone, and a mixture of these.

The content of the colorant is preferably from 1% by mass to 15% by mass, and more preferably from 3% by mass to 10% by mass relative to the toner.

The colorant may be used in the form of a master batch in which it is combined with a resin.

Examples of the resin to be kneaded with the master batch include^ the modified and unmodified polyester resins mentioned above; styrene polymer and substitution products thereof (e.g., polystyrene, polyp-chlorostyrene, and polyvinyl toluene); styrene-based copolymers

(e.g., styrene-p-chlorostyrene copolymer, styrene/propylene copolymer, styrene/vinyl toluene copolymer, styrene/vinyl naphthalene copolymer, styrene/methyl acrylate copolymer, styrene/ethyl acrylate copolymer, styrene butyl acrylate copolymer, styrene/octyl acrylate copolymer, styrene/methyl methacrylate copolymer, styrene/ethyl methacrylate copolymer, styrene/butyl methacrylate copolymer, styrene/methyl crchloromethacrylate copolymer, styrene/acrylonitrile copolymer, styrene/vinyl methyl ketone copolymer, styrene/butadiene copolymer, styrene/isoprene copolymer, styrene/acrylonitrile/indene copolymer, styrene/maleic acid copolymer, and styrene/maleic acid ester copolymer); polymethyl methacrylate,^' polybutyl methacrylate,^' polyvinyl chloride; polyvinyl acetate; polyethylene! polypropylene; polyester; epoxy resin; epoxy polyol resin! polyurethane! polyamide; polyvinyl butyral,^"

polyacrylic acid resin; rosin! modified rosin; terpene resin; aliphatic or alicyclic hydrocarbon resin! aromatic petroleum resin; chlorinated paraffin; and paraffin wax. One of these may be used alone, or two or more of these may be used as a mixture.

The master batch can be obtained by mixing and kneading the resin for master batch and the colorant under a high shearing force.

In this case, it is possible to use an organic solvent in order to enhance the interaction between the colorant and the resin.

Furthermore, it is also possible to use a so-called flushing technique of mixing and kneading an aqueous paste of the colorant containing water with the resin and an organic solvent to transfer the colorant to the resin, and removing the water component and the organic solvent component. According to this method, there is no need of drying, because it is possible to use the wet cake of the colorant as is.

For mixing and kneading, a high shearing disperser such as a 3-roll mill is preferably used. The amount of use of the master batch is preferably from 0.1 parts by mass to 20 parts by mass relative to 100 parts by mass of the binder resin.

It is preferable that the resin for master batch have an acid value of 30 mgKOH/g or less and an amine value of from 1 to 100, and be used with the colorant dispersed therein. It is more preferable that the resin for master batch have an acid value of 20 mgKOH/g or less and an amine value of from 10 to 50, and be used with the colorant dispersed therein.

When the acid value is greater than 30 mgKOH/g, chargeability under high-humidity conditions may be poor, and dispersability of the pigment may also be poor.

The acid value can be measured according to a procedure described in, for example, JIS K0070. The amine value can be measured according to a procedure described in, for example, JIS K7237.

■"Pigment Dispersion Liquid" -

The colorant may also be used in the form of a colorant dispersion liquid in which it is dispersed with a pigment dispersant.

The pigment dispersant is not particularly limited, and an appropriate publicly-known one may be selected according to the purpose.

It is preferable that such a pigment dispersant be highly compatible with the binder resin, in terms of pigment dispersibility. Examples of commercially- available products thereof having such a property include

"AJISPER PB821" and "AJISPER PB822" (manufactured by Ajinomoto

Fine-Techno Co., Inc.), "DISPERBYK-2001" (manufactured by

Byk-Chemie GmbH), and "EFKA-4010" (manufactured by EFKA Corporation).

The pigment dispersant preferably has a weight average

molecular weight of from 500 to 100,000 as a styrene -equivalent

molecular weight at the local maximum of a main peak obtained by gel permeation chromatography. In this range, the weight average

molecular weight is more preferably from 3,000 to 100,000, particularly preferably from 5,000 to 50,000, and most preferably from 5,000 to 30,000, in terms of pigment dispersibility. When the molecular weight is less than 500, the polarity of the pigment dispersant may be strong to have a poor colorant dispersibility. When the molecular weight is greater than 100,000, the pigment dispersant may be highly affinitive with the solvent to have a poor colorant dispersibility.

The additive amount of the pigment dispersant is preferably from 1 part by mass to 200 parts by mass, and more preferably from 5 parts by mass to 80 parts by mass relative to 100 parts by mass of the colorant. When the additive amount is less than 1 part by mass, the pigment dispersant may have a poor dispersing ability. When the additive amount is greater than 200 parts by mass, chargeability may be poor. ---Releasing Agent-

Examples of the releasing agent include : aliphatic

hydrocarbon-based wax such as aliphatic hydrocarbon-wax, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin wax, microcrystalline wax, paraffin wax, and Sasol wax! oxide of aliphatic hydrocarbon-based wax such as polyethylene oxide wax or block

copolymer thereof; plant wax such as candelilla wax, carnauba wax, Japan tallow, and jojoba wax,^" animal wax such as beeswax, lanolin, and cetaceum; mineral wax such as ozokerite, ceresin, and petrolatum; wax mainly made of fatty acid ester, such as montanoic acid ester wax and caster wax,^' various synthetic ester waxes; and synthetic amide waxes.

Other examples of the releasing agent include: saturated straight-chain fatty acid such as palmitic acid, stearic acid, montanoic acid, and other straight-chain alkyl carboxylic acids having a

straight-chain alkyl group; unsaturated fatty acid such as prandin acid, eleostearic acid, and parinaric acid; saturated alcohol such as stearyl alcohol, eicosyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, mesilyl alcohol, and other long-chain alkyl alcohols; polyhydric alcohol such as sorbitol; fatty acid amide such as linoleic acid amide, olefin acid amide, and lauric acid amide; saturated fatty acid bisamide such as methylenebis capric acid amide, ethylenebis lauric acid amide, and hexamethylenebis stearic acid amide; unsaturated fatty acid amide such as ethylenebis oleic acid amide, hexamethylenebis oleic acid amide, and

Ν,Ν'-dioleylsebacic acid amide; aromatic bisamide such as nvxylenebis stearic acid amide and Ν,Ν-distearyl isophthalic acid amide; fatty acid metal salt such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; wax obtained by grafting aliphatic

hydrocarbon-based wax with vinyl-based monomer such as styrene and acrylic acid; partial ester compound of fatty acid and polyhydric alcohol, such as behenic acid monoglyceride; and methyl ester compound having a hydroxyl group obtained by hydrogenating vegetable fat and oil.

Other preferable examples of the releasing agent include products obtained by making the molecular weight distribution of these waxes sharp by press sweating, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method, or a solution crystallization method, and products obtained by removing a low molecular weight solid fatty acid, a low molecular weight solid alcohol, a low molecular weight solid compound, and other impurities from these waxes.

The melting point of the releasing agent is preferably 65°C or higher, and more preferably from 69°C to 120°C, in order to achieve a balance between fixability and offset resistance.

When the melting point is 65°C or higher, blocking resistance will not be poor. When the melting point is 120°C or lower, offset resistance will be expressed sufficiently.

In the present invention, the temperature of a peak top of a maximum peak among endothermic peaks of the releasing agent measured according to differential scanning calorimetry (DSC) is the melting point of the releasing agent.

The DSC measurement instrument for measuring the melting point of the releasing agent and the toner is preferably a highly precise inner heat type input compensation differential scanning calorimeter.

The measurement procedure is based on ASTM D3418-82. A DSC curve used in the present invention is one that is measured by raising the temperature at a temperature raising rate of 10°C/min, after once raising and lowering the temperature to obtain a previous history.

The content of the releasing agent is preferably from 1 part by mass to 50 parts by mass relative to 100 parts by mass of the binder resin, although the preferable range varies according to the melt viscoelasticity and the fixing method of the binder resin.

■^■■Charge Controlling Agent- -- The charge controlling agent is not particularly limited, and an appropriate publicly-known one may be selected according to the purpose. Examples thereof include nigrosine dyes, triphenylmethane dyes, chrome -containing metal complex dyes, molybdic acid chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine -modified quaternary ammonium salts), alkylamides, phosphorus or phosphorus compounds, tungsten or tungsten compounds, fluorine active agents, metal salts of salicylic acid, and metal salts of salicylic acid derivatives. Specific examples include nigrosine dye BONTRON 03, quaternary ammonium salt BONTRON P-51, metal-containing azo dye BONTRON S-34, oxynaphthoic acid-based metal complex E-82, salicylic acid-based metal complex E-84 and phenol condensate E-89 (these manufactured by ORIENT CHEMICAL INDUSTRIES CO., LTD);

quaternary ammonium salt molybdenum complex TP-302 and TP-415 (both manufactured by Hodogaya Chemical Co., Ltd.); quaternary ammonium salt COPY CHARGE PSY VP 2038, triphenylmethane derivative COPY BLUE PR, quaternary ammonium salt COPY CHARGE

NEG VP2036 and COPY CHARGE NX VP434 (these manufactured by

CLARIANT K.K.); LRA-901 and boron complex LR-147 (manufactured by

Japan Carlit Co., Ltd.); copper phthalocyanine; perylene; quinacridone; azo pigments! polymeric compounds having, as a functional group, a sulfonic acid group, carboxyl group, quaternary ammonium salt, etc;

phenol-based resin.^" and fluorine -based compound.

The amount of use of the charge controlling agent is not

determined flatly and is varied depending on the type of the binder resin used, on an optionally used additive, and on the toner production method used (including the dispersion method). The amount of use of the charge controlling agent is preferably from 0.1 parts by mass to 10 parts by mass, and more preferably from 0.2 parts by mass to 5 parts by mass, relative to 100 parts by mass of the binder resin. When the amount of use of the charge controlling agent is greater than 10 parts by mass, toner fixability may be inhibited.

In terms of production stability, it is preferable to dissolve the charge controlling agent in an organic solvent, while it is also possible to finely disperse the charge controlling agent in an organic solvent with a beads mill, or the like.

<Toner>

The volume average particle diameter of the toner of the present invention is preferably from 1 μπι to 8 μιη in terms of forming a highly precise high-quality image having a high resolution.

The particle size distribution (volume average particle

diameter/number average particle diameter) of the toner is preferably from 1.00 to 1.15 in terms of maintaining stable images for a long term.

Further, it is preferable that the toner have a second peak particle diameter that is at least from 1.21 to 1.31 times as large as the most frequent diameter in the volume -basis particle size distribution. When the toner has no such second peak particle diameter, particularly when the value (volume average particle diameter/number average particle diameter) is close to 1.00 (monodisperse), closest packability of the toner will be very high, which makes it likely for initial flowability degradation and cleaning failure to occur. Further, when the toner has a peak particle diameter that is greater than 1.31 times as large, image granularity will be poor because the toner will contain a lot of coarse particles, which is unfavorable.

As other additives, external additives such as a flowability improver and a cleanability improver may be added to the toner of the present invention according to necessity.

-Flowability improver-

A flowability improver may be added to the toner of the present invention. By being added to the surface of the toner, the flowability improver improves flowability of the toner (makes the toner flowable).

The flowability improver is not particularly limited, and an appropriate one may be selected according to the purpose. Examples thereof include^ fine particles of metal oxides [e.g., fine particle silica (wet silica, dry silica, etc.), fine particle titanium oxide, and fine particle alumina], and treated silica, treated titanium oxide, and treated alumina obtained by treating their surface with a silane coupling agent, a titanium coupling agent, silicone oil, or the like; and fluorine-based resin particles such as vinylidene fluoride fine particles and

polytetrafluoroethylene fine particles. Among these, fine particle silica, fine particle titanium oxide, and fine particle alumina are preferable, and treated silica obtained by treating the surface of the fine particle silica with a silane coupling agent or silicone oil is more preferable.

As the particle diameter of the flowability improver, an average primary particle diameter thereof is preferably from 0.001 μιη to 2 μιη, and more preferably from 0.002 μιη to 0.2 μιη.

The fine particle silica is fine particles produced from gas-phase oxidation of silicon halide, and called dry silica or fumed silica.

Examples of commercially-available products of silica fine particles produced from gas-phase oxidation of silicon halide include^ AEROSIL (product name of Nippon Aerosil Co., Ltd., the same applies hereafter)- 130, -300, -380, -TT600, -MOX170, -MOX80, and -COK84;

Ca-O-SiL (product name of CABOT Corporation)-M-5, -MS-7, -MS-75, -HS-5, and -EH-5; WACKER HDK (product name of WACKER-CHEMIE GmbH)-20 V15, -N20E, -T30, and -T40; D-CFineSilica (product name of Dow Corning Corporation); and Fransol (product name of Fransil

Corporation).

Treated silica fine particles obtained by hydrophobizing silica fine particles produced from gas-phase oxidation of silicon halide are more preferable. To obtain the treated silica fine particles, treatment of the silica fine particle is performed such that hydrophobicity thereof

measured by a methanol titration test will be preferably from 30% to 80%.

The silica fine particles are imparted hydrophobicity by being reacted chemically or physically with an organosilicon compound or the like that is reactive with or physically adsorbs to the silica fine particles. A preferable method is to treat silica fine particles produced from gas-phase oxidation of a silicon halide compound with an organosilicon compound.

Examples of the organosilicon compound include hydroxypropyl trimethox silane, phenyl trimethoxy silane, n-hexadecyl trimethoxy silane, n-octadecyl trimethoxy silane, vinyl methoxy silane, vinyl trie thoxy silane, vinyl triacetoxysilane, dimethylvinylchlorosilane, divinylchlorosilane, γ-methacryloxypropyltrimethoxy silane, hexamethyldisilane,

trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane,

methyltrichlorosilane, allyldimethylchlorosilane,

allylphenyldichlorosilane, benzyldimethylchlorosilane,

bromomethyldimethylchlorosilane, a-chloroethyltrichlorosilane,

β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,

triorganosilylmercaptan, trimethylsilylme reap tan, triorganosilylacrylate, vinyldimethylacetoxysilane , dimethylethoxy silane , trimethylethoxy silane , trimethylmethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule, and having 0 to 1 hydroxyl group bonded with Si at each terminal siloxane unit. Further examples include silicone oils such as a dimethylsilicone oil. One of these may be used alone, or two or more of these may be used as a mixture.

The number average particle diameter of the flowability improver is preferably from 5 nm to 100 nm, and more preferably from 5 nm to 50 nm.

As the specific surface area of the flowability improver, a nitrogen adsorption specific surface area measured according to a BET procedure, is preferably 30 m²/g or greater, and more preferably from 60 m²/g to 400 m²/g.

When the flowability improver is surface-treated fine particles, the specific surface area thereof is preferably 20 m²/g or greater, and more preferably from 40 m²/g to 300 m²/g.

The amount of application of the flowability improver is

preferably from 0.03 parts by mass to 8 parts by mass relative to 100 parts by mass of toner particles.

■Cleanability Improver-

A cleanability improver for improving clearability of the toner remained on an electrostatic latent image bearing member or a primary transfer medium after the toner is transferred onto a recording sheet or the like is not particularly limited, and an appropriate one may be selected according to the purpose. Examples thereof include: fatty acid metal salt such as zinc stearate, calcium stearate, and stearic acid; and polymer fine particles produced by soap -free emulsion polymerization, such as polystyrene fine particles. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle diameter of from 0.01 μπι to 1 μπι.

These flowability improver, cleanability improver, etc. are also called external additives because they are used as deposited or fixed on the surface of the toner. The method for externally adding such external additives to the toner is not particularly limited, and an appropriate method may be selected according to the purpose. For example, various types of particle mixers, or the like are used. Examples of the particle mixers include a V type mixer, a rocking mixer, a Lodige mixer, a Nauta mixer, and a Henschel mixer. Examples of particle mixers used for when also performing fixing include a hybridizer, a mechanofusion, and a Q-mixer.

«Developer»

The toner of the present invention may be used as a

two-component developer as mixed with a carrier.

■Carrier-

The carrier is not particularly limited, and an appropriate one may be selected according to the purpose. Examples thereof include carriers such as ferrite and magnetite, and a resin-coated carrier. The resin-coated carrier is made up of carrier core particles, and a coating material that is a resin for covering (coating) the surface of the carrier core particles. Preferable examples of the resin used as the coating material include : styrene/acrylic-based resin such as styrene/acrylic acid ester copolymer and styrene/methacrylic acid ester copolymer,^'

acrylic-based resin such as acrylic acid ester copolymer and methacrylic acid ester copolymer; fluorine -containing resin such as

polytetrafluoroethylene, monochlorotrifluoroethylene polymer, and polyvinylidene fluoride! silicone resin; polyester resin; polyamide resin! polyvinyl butyral, and amino acrylate resin. Other examples include resin usable as a coating material of the carrier, such as ionomer resin and polyp henylene sulfide resin. One of these may be used alone, or two or more of these may be used in combination. A binder-type carrier core, which is obtained by dispersing magnetic particles in a resin, may also be used as the carrier. For the resin-coated carrier, examples of the method for coating the surface of the carrier core with at least a resin coating agent include a method of dissolving or suspending the resin in a solvent and applying the resultant to the carrier core to thereby deposit the resin thereon, and a method of simply mixing them in their particle states. The ratio of use of the resin coating material to the resin-coated carrier is not particularly limited and may be appropriately selected according to the purpose. However, it is preferably from 0.01% by mass to 5% by mass, and more preferably from 0.1% by mass to 1% by mass relative to 100 parts by mass of the resin-coated carrier.

When the resin coating material is a mixture of two or more kinds of components, examples of use thereof for coating the magnetic material include (l) and (2) below.

(1) A mixture (12 parts by mass) of dimethyldichlorosilane and dimethylsilicone oil (with a mass ratio of 1^5) to treat titanium oxide fine particles (100 parts by mass)

(2) A mixture (20 parts by mass) of dimethyldichlorosilane and dimethylsilicone oil (with a mass ratio of 1^5) to treat silica fine particles (100 parts by mass).

For example, styrene/methyl methacrylate copolymer, a mixture of fluorine -containing resin and a styrene-based copolymer, and a silicone resin are preferably used as the resin coating material. Among these, the silicone resin is particularly preferable. Examples of the mixture of fluorine-containing resin and styrene-based copolymer include: a mixture of polyvinylidene fluoride and styrene/methyl methacrylate copolymer; a mixture of

polytetrafluoroethylene and styrene/methyl methacrylate copolymer; and a mixture of vinylidene fluoride/tetrafluoroethylene copolymer (with a mass ratio of the copolymer of from 10:90 to 90:10), styrene/2-ethylhexyl acrylate copolymer (with a mass ratio of the copolymer of from 10:90 to 90^:10), and styrene/2-ethylhexyl acrylate/methyl methacrylate copolymer (with a mass ratio of the copolymer of 20 to 60 : 50 to 30 : 10 to 50).

Examples of the silicone resin include a modified silicone resin produced by reacting a nitrogen-containing silicone resin and a nitrogen-containing silane coupling agent with the silicone resin.

Examples of the magnetic material as the carrier core include: oxide such as ferrite, iron-overload ferrite, magnetite, and γ-iron oxide; and metal such as iron, cobalt, and nickel, and alloy thereof. Examples of elements contained in these magnetic materials include iron, cobalt, nickel, aluminum, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, calcium, manganese, selenium, titanium, tungsten, and vanadium. Among these magnetic materials, preferable examples include: copper/zinc/iron-based ferrite mainly made of copper, zinc, and iron; and manganese/magnesium/iron-based ferrite mainly made of manganese, magnesium, and iron.

The volume resistance of the carrier can be set by appropriately adjusting the degree of undulations in the carrier surface, and the amount of the coating resin. For example, it is preferably from 10⁶ Ω-cm to 10¹⁰ Ω-cm. The particle diameter of the carrier is not particularly limited, and may be appropriately selected according to the purpose. However, it is preferably from 4 μπι to 200 μπι, more preferably from 10 μπι to 150 μπι, and particularly preferably from 20 μπι to 100 μηι.

Among these, a 50% particle diameter of from 20 μπι to 70 μιη is the most preferable as the particle diameter of the resin-coated carrier. For a two-component developer, it is preferable to use the toner of the present invention in an amount of from 1 part by mass to 200 parts by mass relative to 100 parts by mass of the carrier, and it is more preferable to use the toner in an amount of from 2 parts by mass to 50 parts by mass relative to 100 parts by mass of the carrier.

In a developing method using the toner of the present invention, any electrostatic latent image bearing member conventionally used in electrophotography may be used. Preferable examples thereof include an organic electrostatic latent image bearing member, an amorphous silica electrostatic latent image bearing member, a selenium electrostatic latent image bearing member, and zinc oxide electrostatic latent image bearing member.

(Toner Production Method)

An example of a specific production method will be presented below.

To obtain the toner having the properties of the present invention can be achieved by the toner being produced through a liquid droplet forming step of forming liquid droplets by discharging a toner composition liquid obtained by dissolving or dispersing at least a binder resin and a releasing agent in a solvent, and a liquid droplet solidifying step of solidifying the liquid droplets to thereby form fine particles.

Here, for example, a wax is used as the releasing agent, and the releasing agent must dissolve in the toner composition liquid. Hence, from among commonly used waxes, an appropriate one that can dissolve in a solvent used for the toner composition liquid may be selected.

It is also possible to dissolve the releasing agent by heating a solvent and the toner composition liquid. Here, in order for the toner composition liquid to be continuously discharged stably, it is preferable that the toner composition liquid have a temperature in the liquid droplet solidifying step of lower than [Tb-20]°C, where Tb (°C) is the boiling point of the solvent (e.g., an organic solvent).

As long as the toner composition liquid has a temperature of lower than [Tb-20]°C, it will not produce air bubbles in a toner

composition liquid chamber, or will not narrow the discharge holes by drying near the discharge holes, which realize stable discharging.

In order to prevent clogging of the discharge holes, it is necessary for the releasing agent to be dissolved in the toner composition liquid.

Further, it is important for the releasing agent to be dissolved in the toner composition liquid without being phase-separated from the binder resin dissolved therein, in order to obtain uniform toner particles.

Furthermore, it order for the releasing agent to exert the releasing property during fixing and prevent offset, it is important for the releasing agent to be phase-separated from the binder resin in the toner particles from which the solvent has been removed. When the releasing agent is not phase-separated from the binder resin, it not only cannot exert the releasing property, but also makes the melt viscosity and melt elasticity of the binder resin lower, which makes it likely for hot offset to occur.

Therefore, an appropriate releasing agent is selected depending on an organic solvent and a binder resin to be used.

"Solvent"

The solvent is not particularly limited, and an appropriate one may be selected according to the purpose as long as it is a volatile one in which the toner composition can dissolve or disperse. Preferable examples thereof include solvents such as ethers, ketones, esters, hydrocarbons, and alcohols, and particularly preferable examples include tetrahydrofuran (THF), acetone, methyl ethyl ketone (MEK), ethyl acetate, toluene, and water. One of these may be used alone, or two or more of these may be used in combination.

"Method for Preparing Toner Composition Liquid"

The toner composition liquid can be obtained by dissolving or dispersing the toner composition in a solvent.

In the preparation of the toner composition liquid, it is important to make dispersions of the colorant, etc. sufficiently minute with respect to the opening size of the nozzles, in order to prevent clogging of the discharge holes.

The solid content of the toner composition liquid is preferably from 3% by mass to 40% by mass. When the solid content is less than

3% by mass, not only is productivity low, but also it is likely for the dispersions of the colorant, etc. to settle out or agglomerate, which makes the composition uneven from toner particle to toner particle and degrades the toner quality. When the solid content is greater than 40% by mass, it may not be impossible to obtain a toner with a small particle size.

An example of a production equipment of the toner of the present invention will be explained below with reference to Fig. 3 to Fig. 9. The production equipment of the toner of the present invention is divided into a liquid droplet discharging unit and a liquid droplet solidifying/collecting unit. Each will be explained below.

[Liquid Droplet Discharging Unit]

The liquid droplet discharging unit is not particularly limited, and a publicly-known one can be used as long as it discharges liquid droplets having a narrow particle size distribution. Examples of the liquid droplet discharging unit include one fluid nozzle, two fluid nozzles, a membrane oscillation type discharging unit, a Rayleigh breakup type discharging unit, a liquid oscillation type discharging unit, and a liquid column resonance type discharging unit. A membrane oscillation type liquid droplet discharging unit is described in, for example, JP-A No. 2008-292976. A Rayleigh breakup type liquid droplet discharging unit is described in, for example, Japanese Patent (JP-B) No. 4647506. A liquid oscillation type liquid droplet discharging unit is described in, for example, JP-A No. 2010-102195.

To make the particle size distribution of the liquid droplets narrow and secure toner productivity at the same time, it is possible to utilize, for example, liquid drop forming liquid column resonance. In liquid droplet forming liquid column resonance, a vibration is applied to a liquid in a liquid column resonance liquid chamber to form a standing wave based on a liquid column resonance, so that the liquid may be discharged from a plurality of discharge holes formed in a region corresponding to an anti-node region of the standing wave.

[Liquid Column Resonance Discharging Unit]

A liquid column resonance type discharging unit configured to discharge droplets by utilizing resonance of a liquid column will be explained.

Fig. 3 shows a liquid column resonance liquid droplet discharging unit 11. It includes a common liquid supply path 17 and a liquid column resonance liquid chamber 18. The liquid column resonance liquid chamber 18 communicates with the common liquid supply path 17 formed at one of wall surfaces on both ends in the longer-direction thereof. The liquid column resonance liquid chamber 18 includes discharge holes 19 for discharging liquid droplets 21, which are formed in one of wall surfaces that connect with the wall surfaces on the both ends, and a vibration generating unit 20 provided on a wall surface opposite to the wall surface in which the discharge holes 19 are formed and configured to generate a high frequency vibration in order to form a liquid column resonance standing wave. An unillustrated high frequency power source is connected to the vibration generating unit 20.

In the present invention, the liquid to be discharged by the discharging unit is in a state of the components of the fine particles to be obtained being dissolved or dispersed (fine particle component-containing liquid), or needs not contain a solvent as long as it is in a liquid state under the discharging conditions, or is in a state of the fine particle components being melted (fine particle component melted liquid).

Hereinafter, the following explanation will be given by denoting the liquid in these states as "toner composition liquid", for explanation of the cases of toner production.

The toner composition liquid 14 flows through a liquid supply pipe by an unillustrated liquid circulating pump, flows into the common liquid supply path 17 of a liquid column resonance liquid droplet forming unit

10 shown in Fig. 4, and is supplied into the liquid column resonance liquid chamber 18 of the liquid column resonance liquid droplet

discharging unit 11 shown in Fig. 3. A pressure distribution is formed in the liquid column resonance liquid chamber 18 filled with the toner composition liquid 114, due to a liquid column resonance standing wave generated by the vibration generating unit 20. Then, liquid droplets 21 are discharged from the discharge holes 19 which are located in a region corresponding to an anti-node region of the standing wave in which the liquid column resonance standing wave has high amplitudes and large pressure pulsation. An anti-node region of the liquid column resonance standing wave means a region other than a node of the standing wave.

It is preferably a region in which the pressure pulsation of the standing wave has high amplitudes enough to discharge the liquid, and more preferably a region including regions that are on both sides of a position at which the amplitude of the pressure standing wave reaches a local maximum (i.e., a node of the velocity standing wave) and that are within

1/4, as measured from the local maximum, of the wavelength extending from the local maximum of the amplitude to local minimums thereof.

Even when a plurality of discharge holes are formed, as long as they are formed within a region corresponding to an anti-node of the standing wave, substantially uniform liquid droplets can be formed from the respective discharge holes. Moreover, liquid droplets can be

discharged efficiently, and the discharge holes are less likely to be clogged. The toner composition liquid 14 having flowed through the common liquid supply path 17 is returned to a raw material container through an unillustrated liquid returning pipe. When the amount of the toner composition liquid 14 in the liquid column resonance liquid chamber 18 decreases by the discharging of the liquid droplets 21, a suction power acts due to the effect of the liquid column resonance standing wave in the liquid column resonance liquid chamber 18, to thereby increase the flow rate of the toner composition liquid 14 to be supplied from the common liquid supply path 17. As a result, the liquid column resonance liquid chamber 18 is refilled with the toner composition liquid 14. When the liquid column resonance liquid chamber 18 is refilled with the toner composition liquid 14, the flow rate of the toner composition liquid 14 flowing through the common liquid supply path 17 returns to as before.

The liquid column resonance liquid chamber 18 of the liquid column resonance liquid droplet discharging unit 11 is formed by joining together frames each made of a material having stiffness high but uninfluential to the liquid resonance frequency at a driving frequency, such as metal, ceramics, and silicon. Further, as shown in Fig. 3, the length L between the wall surfaces on the longer-direction both ends of the liquid column resonance liquid chamber 18 is determined based on a liquid column resonance principle described later. The width W of the liquid column resonance liquid chamber 18 shown in Fig. 4 is preferably smaller than 1/2 of the length L of the liquid column resonance liquid chamber 18, so as not to give any extra frequency to the liquid column resonance. Further, it is preferable to provide a plurality of liquid column resonance liquid chambers 18 in one liquid droplet forming unit

10, in order to improve the productivity drastically. The number of the liquid chambers 18 is not limited, but one liquid droplet forming unit including 100 to 2,000 liquid column resonance liquid chambers 18 is the most preferable, because operability and productivity can both be satisfied. A liquid supply path that leads from the common liquid supply path 17 is connected to each liquid column resonance liquid chamber, and the common liquid supply path 17 hence communicates with the plurality of liquid column resonance liquid chambers 118.

The vibration generating unit 20 of the liquid column resonance liquid droplet discharging unit 11 is not particularly limited as long as it can be driven at a predetermined frequency, but one that is obtained by pasting a piezoelectric element on an elastic plate 9 is preferable. The elastic plate constitutes part of the wall of the liquid column resonance liquid chamber in order to prevent the piezoelectric element from contacting the liquid. The piezoelectric element may be, for example, piezoelectric ceramics such as lead zirconate titanate (LZT), and is often used in the form of a laminate because the amount of displacement is small. Other examples thereof include piezoelectric polymer such as polyvinylidene fluoride (PVDF), and monocrystals such as crystal,

LiNb0₃, LiTa0₃, and KNb0₃. Further, the vibration generating unit 20 is preferably provided such that it can be controlled individually per liquid column resonance liquid chamber. Further, the vibration generating unit is preferably a block-shaped vibration member made of one of the above materials and partially cut according to the geometry of the liquid column resonance liquid chamber, so that it is possible to control each liquid column resonance liquid chamber individually via the elastic plate.

The diameter (Dp) of the opening of the discharge hole 19 is preferably from 1 [μπι] to 40 [μιη]. When the diameter is less than 1

[μιη], a toner may not be obtained because the liquid droplet to be formed will be too small. Further, when solid fine particles of a pigment, etc. are added as a toner constituent component, the discharge holes 19 may be clogged often to thereby lower the productivity. When the diameter is greater than 40 [μιη], the diameter of the liquid droplet will be large.

When obtaining a desired toner particle diameter of from 3 μπι to 6 μπι by drying and solidifying the large liquid droplets, it is necessary to dilute the toner composition to a very thin liquid with an organic solvent, which inconveniently necessitates a lot of drying energy for obtaining a predetermined amount of toner. It is preferable to employ the

configuration of arranging the discharge holes 19 in the direction of width of the liquid column resonance liquid chamber 18 as can be seen from Fig.

4, because this makes it possible to provide many discharge holes 19, and hence improves the production efficiency. Further, because the liquid column resonance frequency varies depending on the positions at which the discharge holes 19 are opened, it is preferable to determine the liquid column resonance frequency appropriately by confirming liquid droplet discharging.

The cross -sectional shape of the discharge hole 19 is illustrated in Fig. 3, etc. as a taper shape with which the diameter of the opening decreases. However, an appropriate cross-sectional shape may be selected.

Next, the mechanism by which the liquid droplet forming unit forms liquid droplets based on liquid column resonance will be explained.

First, the principle of the liquid column resonance phenomenon that occurs in the liquid column resonance liquid chamber 18 of the liquid column resonance liquid droplet discharging unit 11 shown in Fig. 3 will be explained.

When the sound velocity of the toner composition liquid in the liquid column resonance liquid chamber is c, and the driving frequency applied by the vibration generating unit 20 to the toner composition liquid serving as a medium is f, the wavelength λ at which a resonance of the liquid occurs is in the relationship of^:

λ = c/f —(Formula l).

In the liquid column resonance liquid chamber 18 of Fig. 3, the length from a frame end at the fixed end side to the end at the common liquid supply path 17 side is L, the height hi (= about 80 [μιη]) of the frame end at the common liquid supply path 17 side is about double the height h2 (= about 40 [μιη]) of a communication port, and it is assumed that this end is equivalent to a closed fixed end. When both ends are fixed like this, a resonance is formed the most efficiently when the length L corresponds to an even multiple of 1/4 of the wavelength λ. This is expressed by the following formula 2.

L = (Ν/4)λ —(Formula 2)

(where N is an even number.)

The above formula 2 can also be established in the case of both-side free ends, where both ends are completely opened.

Likewise, when one end is equivalent to a free end that allows the pressure to escape, and the other end is closed (fixed end), i.e., in the case of one-side fixed end or one-side free end, a resonance is formed the most efficiently when the length L corresponds to an odd multiple of 1/4 of the wavelength λ. That is, the value N in the above formula 2 is represented by an odd number.

The most efficient driving frequency f is derived from the above formulae 1 and 2 as^

f = Nxc/(4L) ---(Formula 3).

However, actually, the vibration is not amplified unlimitedly, because the liquid has viscosity that may attenuate the resonance. The liquid has the Q-value, and also resonates at a frequency close to the most efficient driving frequency f expressed by the formula 3, as shown by formulae 4 and 5 described below.

Fig. 5A to Fig. 5D show the shapes of standing waves of velocity and pressure pulsation (resonance mode) when N = 1, 2, and 3. Fig. 6A to Fig. 6C show the shapes of standing waves of velocity and pressure pulsation (resonance mode) when N = 4 and 5. Although a standing wave is basically a compression wave (longitudinal wave), it is commonly expressed as in Fig. 5A to Fig. 5D and Fig. 6A to Fig. 6C. The solid line is a velocity standing wave (V), and a dotted line is a pressure standing wave (P). For example, as can be seen from Fig. 5A showing a case of one-side fixed end where N=l, the amplitude of the velocity distribution is zero at the closed end, and the maximum at the opened end, and hence the velocity distribution is understandable intuitively. When the length between the longer-direction both ends of the liquid column resonance liquid chamber is L and the wavelength of a liquid column resonance of the liquid is λ, a standing wave occurs the most efficiently when the integer N = 1 to 5. Further, the pattern of a standing wave varies depending on whether both ends are opened or closed. Therefore, these information are also described in the drawings. As will be described later, the conditions of the ends are determined depending on the state of the openings of the discharge holes and the state of the opening of the supplying side.

In the acoustics, an opened end is a longer-direction end at which the moving velocity of the medium (liquid) reaches a local maximum, and at which the pressure reaches a local minimum to the contrary.

Conversely, a closed end is defined as an end at which the moving velocity of the medium is zero. A closed end is considered an acoustically hard wall, which reflects a wave. When an end is ideally perfectly closed or opened, a resonance standing wave as shown in Fig. 5A to Fig. 5D and

Fig. 6A to Fig. 6C occurs by superposition of waves. However, the pattern of a standing wave varies depending also on the number of discharge holes and the positions at which the discharge holes are opened, and hence a resonance frequency appears in a region shifted from a region derived from the above formula 3. In this case, it is possible to create stable discharging conditions by appropriately adjusting the driving frequency. For example, when a sound velocity c of the liquid of

1,200 [m/s] and a length L of the liquid column resonance liquid chamber of 1.85 [mm] are used, and a resonance mode completely equivalent to both-side fixed ends with walls present on both ends, where N=2, is used, the most efficient resonance frequency is derived as 324 kHz from the above formula 2. In another example in which the same conditions as above, i.e., the sound velocity c of the liquid of 1,200 [m/s] and the length

L of the liquid column resonance liquid chamber of 1.85 [mm] are used, and a resonance mode equivalent to both-side fixed ends with walls present on both ends, where N=4, is used, the most efficient resonance frequency is derived as 648 kHz from the above formula 2. Like this, a lower-order resonance and a higher-order resonance can both be utilized in the same liquid column resonance liquid chamber.

In order to increase the frequency, it is preferable that the liquid column resonance liquid chamber of the liquid column resonance liquid droplet discharging unit 11 shown in Fig. 3 have a state equivalent to a closed end state at both ends, or have ends that could be described as acoustically soft walls owing to influences from the openings of the discharge holes. However, this is not limiting, and the ends may be free ends. Here, the influences from the openings of the discharge holes mean that there is a smaller acoustic impedance, and particularly that there is a larger compliance component. Therefore, a configuration as shown in Fig. 5A and Fig. 6A, in which walls are formed at

longer- direction both ends of the liquid column resonance liquid chamber, is preferable, because a both-side fixed ends resonance mode and all one-side free end resonance modes in which the discharge hole side is regarded as being opened, can be used in such a configuration.

The number of openings of the discharge holes, the positions at which the openings are formed, and the cross -sectional shape of the discharge holes are also the factors that determine the driving frequency.

The driving frequency can be appropriately determined based on these factors. For example, when the number of discharge holes is increased, the liquid column resonance liquid chamber gradually becomes less unfree at an end thereof that has been the fixed end, and a resonance standing wave that is substantially the same as a standing wave in the case of an opened end will occur. Therefore, the driving frequency will be high. Further, the unfree condition becomes weaker, as starting from the position at which the discharge hole that is the closest to the liquid supply path is opened. The cross-sectional shape of the discharge hole may be changed to a round shape, or the volume of the discharge hole may be changed based on the thickness of the frame. Hence, actually, the wavelength of a standing wave may be short, and the frequency thereof may be higher than the driving frequency. When a voltage is applied to the vibration generating unit at the driving frequency determined in this way, the vibration generating unit deforms, and a resonance standing wave occurs the most efficiently at the driving frequency. A liquid column resonance standing wave also occurs at a frequency close to the driving frequency at which a resonance standing wave occurs the most efficiently. That is, when the length between the longer- direction both ends of the liquid column resonance liquid chamber is L and the distance to the discharge hole that is the closest to the liquid supply side end is Le, it is possible to induce a liquid column resonance and discharge liquid droplets from the discharge holes, by vibrating the vibration generating unit with a driving waveform, of which main component is the driving frequency f, which is in the range determined by the formulae 4 and 5 below using both of the lengths L and Le.

Nxc/(4L) < f < Nxc/(4Le) - - - (Formula 4)

Nxc/(4L) < f < (N+l)xc/(4Le) —(Formula 5)

It is preferable that the ratio between the length L between the longer- direction both ends of the liquid column resonance liquid chamber and the distance Le to the discharge hole that is the closest to the liquid supply side end satisfy Le/L > 0.6.

Based on the principle of the liquid column resonance

phenomenon described above, a liquid column resonance pressure standing wave is formed in the liquid column resonance liquid chamber

18 of Fig. 3, and liquid droplet discharging occurs continuously from the discharge holes 19 provided in a portion of the liquid column resonance liquid chamber 118. It is preferable to provide the discharge holes 19 at a position at which the pressure of the standing wave reaches the maximum pulsation, because this improves the discharging efficiency and allows driving at a lower voltage. Further, the number of discharge holes-19 may be one in one liquid column resonance liquid chamber 18. However, it is preferable to provide a plurality of discharge holes in terms of productivity. Specifically, the number of discharge holes is preferably from 2 to 100.

By providing 100 or less discharge holes, it is possible to suppress the voltage to apply to the vibration generating unit 20 for forming desired liquid droplets from the discharge holes 19 to a low level, which makes it possible to stabilize the behavior of the piezoelectric element as the vibration generating unit 20. In the formation of a plurality of discharge holes 19, the pitch between the discharge holes is preferably from 20 [μιη] to equal to or shorter than the length of the liquid column resonance liquid chamber. By setting the pitch between the discharge holes to 20 [μπι] or greater, it is possible to suppress the possibility that liquid droplets discharged from adjoining discharge holes will collide on each other to form a larger droplet, which makes it possible to obtain a favorable toner particle size distribution.

Next, a liquid column resonance phenomenon that occurs in the liquid column resonance liquid chamber 18 of the liquid droplet

discharging unit 11 of the liquid column resonance liquid droplet forming unit 10 will be described.

Fig. 7A to Fig. 7D are explanatory diagrams exemplarily showing a liquid column resonance phenomenon that occurs in the liquid column resonance liquid chamber 18.

The solid line drawn in the liquid column resonance liquid chamber 18 in Fig. 7A to Pig. 7D represents a velocity distribution V plotting the velocity at arbitrary measuring positions in the longer direction of the liquid column resonance liquid chamber 18. The direction from the wall on the closed side on the left-hand side of the drawing to the wall on the opened side on the right-hand side of the drawing is +, and the opposite direction is -. The dotted line drawn in the liquid column resonance liquid chamber 18 in Fig. 7 A to Fig. 7D represents a pressure distribution P plotting the pressure values at arbitrary measuring positions in the longer direction of the liquid column resonance liquid chamber 18. A pressure on the positive side with respective to the atmospheric pressure is plus, and a pressure on the negative side is minus.

In the present embodiment, the height hi (= about 80 [μπι]) from the bottom surface of the liquid column resonance liquid chamber 18 in the liquid droplet discharging unit 11 to the lower end of a

communication path communicating with the common liquid supply path 17 is set to about double the height h2 (= about 40 [μηα]) of the

communication port, as shown in Fig. 3. Therefore, longer-direction both ends of the liquid column resonance liquid chamber 18 of the present embodiment can be assumed to be substantially approximate to fixed ends. Fig. 7A to Fig. 7D show the temporal changes of the velocity distribution and pressure distribution based on such an assumption.

Fig. 7A shows a pressure waveform and a velocity waveform in the liquid column resonance liquid chamber 18 at the time of discharging liquid droplets. At this time, the pressure of a liquid portion on the closed wall side of the liquid column resonance liquid chamber 18, i.e., a liquid portion (the liquid near the discharge holes) in a liquid chamber region where the discharge holes 19 are provided, reaches a local maximum. As a result, the built-up meniscus pressure pushes out the liquid from the discharge holes 19. After this, the pressure of the liquid near the discharge holes 19 lowers to shift to the negative pressure side, to thereby discharge liquid droplets 21 from the discharge holes 19, as shown in Fig. 7B.

After this, as shown in Fig. 7C, the pressure of the liquid near the discharge holes 19 reaches a local minimum. From this instant, the liquid column resonance liquid chamber 18 starts to be filled with the toner composition liquid 14 through the common liquid supply path 17. Then, as shown in Fig. 7D, the pressure of the liquid near the discharge holes 19 in turn gradually increases to shift to the positive pressure side. At this instant, the liquid chamber is filled up with the toner composition liquid 14, and the pressure of the liquid near the discharge holes 19 of the liquid column resonance liquid chamber 18 reaches a local maximum again, as shown in Fig. 7A.

In this way, a standing wave based on a liquid column resonance occurs in the liquid near the discharge holes 19 of the liquid column resonance liquid chamber 18, with the vibration generating unit 20 driven at a high frequency. Since the discharge holes 19 are provided in a region corresponding to the anti-node of the liquid column resonance standing wave at which the pressure pulsation reaches the maximum, liquid droplets 21 are continuously discharged from the discharge holes 19 synchronously with the cycle of the anti-node.

[Solidification of Liquid Droplets]

The toner of the present invention can be obtained by solidifying and then collecting the liquid droplets of the toner composition liquid discharged into a gas from the above-described liquid droplet discharging unit.

[Liquid Droplet Solidifying Unit]

The method for solidifying the liquid droplets may be arbitrary, basically as long as it can bring the toner composition liquid into a solid state, although the idea may be different depending on the characteristics of the toner composition liquid.

For example, when the toner composition liquid is one that is obtained by dissolving or dispersing the solid raw materials in a volatile solvent, it is possible to solidify the liquid droplets by drying the liquid droplets in a conveying air stream, i.e., by volatilizing the solvent after the liquid droplets are jetted. For drying the solvent, it is possible to adjust the dry state, by selecting the temperature and vapor pressure of the gas to be jetted, the type of the gas, etc. appropriately. The collected particles need not be dried completely, and as long as they retain a solid state, they can be additionally dried in a separate step after collected. This method is not obligatory, and the liquid droplets may be solidified by temperature change, application of a chemical reaction, etc.

In the present invention, the releasing agent that has dissolved needs to recrystallize during solidifying of the liquid droplets, and grow to a size enough for the maximum length Lmax of the releasing agent in a toner particle to be 1.1 or greater times as large as the maximum Feret diameter Df of the toner particle containing the releasing agent. The first means for obtaining this is to dry the liquid droplets under an atmosphere adjusted to equal to or higher than a temperature that is lower than the recrystallization temperature (Tc) of the releasing agent by 5°C. The second means is to dry the liquid droplets under conditions where the relative humidity of the solvent of the toner composition liquid is adjusted to a range of from 10% to 40%, although the atmosphere is lower than the temperature that is lower than the recrystallization temperature (Tc) of the releasing agent by 5°C. Both of the methods promote growth of a sufficient crystalline domain, by slowing down the speed at which the releasing agent recrystallizes or the speed at which the solvent dries.

In the present invention, the second means of drying the liquid droplets under conditions where the relative humidity of the solvent of the toner composition liquid is adjusted to a range of from 10% to 40% is particularly effective. This method can effectively slow down the speed of drying, and can not only promote crystal growth of the releasing agent but also suppress contraction of the volume of the binder resin due to abrupt drying and keep the interface between the releasing agent and the resin at a favorable strength. This method is particularly effective for a problem that the toner is torn up from being stirred for a long time to thereby adhere to any members of an apparatus.

The recrystallization temperature of the releasing agent can be measured according to a DSC procedure. In the present invention, a peak temperature of an exothermic peak that is observed when the temperature is lowered to 0°C at a rate of 10°C/min after the temperature is raised to 150°C at a temperature raising rate of 10°C/min is defined as the recrystallization temperature. When the atmosphere temperature is lower than the temperature that is lower than the recrystallization temperature of the releasing agent by 5°C, the speed at which

recrystallization advances will be high, which makes it less easy for a releasing agent having a sufficient length or branch to be formed.

In the second method, when the relative humidity of the solvent of the toner composition liquid is lower than 10%, the speed at which the solvent dries will be high likewise, which is unfavorable because recrystallization of the releasing agent will be promoted and a releasing agent occupying a relatively small domain will likely be formed. On the other hand, when the relative humidity is higher than 40%, the speed at which the solvent dries will be significantly low, which promotes mutual merging and fusion of the toner particles during drying, and makes it harder to obtain a toner having a desired particle size distribution.

[Solidified Particle Collecting Unit]

The solidified particles can be collected from the gas with a publicly-known powder collecting unit such as a cyclone collector and a back filter.

Fig. 8 is a cross-sectional diagram of an example of an apparatus that carries out the toner producing method of the present invention.

The toner producing apparatus 1 mainly includes a liquid droplet discharging unit 2 and a drying/collecting unit 60. A raw material container 13 that contains the toner composition liquid 14, and a liquid circulating pump 15 are joined to the liquid droplet discharging unit 2. The liquid circulating pump is configured to supply the toner composition liquid 14 contained in the raw material container 13 into the liquid droplet discharging unit 2 through a liquid supply pipe 16 and to pneumatically convey the toner composition liquid 14 in the liquid supply pipe 16 in order to return the toner composition liquid into the raw material container 13 through a liquid returning pipe 22. The toner composition liquid 14 can be supplied into the liquid droplet discharging unit 2 at any time. A pressure gauge PI is provided on the liquid supply pipe 16, and a pressure gauge P2 is provided on the drying/collecting unit. The pressure at which the liquid is fed into the liquid droplet discharging unit 2 is managed by the pressure gauge PI, and the pressure in the drying/collecting unit is managed by the pressure gauge P2. In this case, when P1>P2, there is a risk that the toner composition liquid 14 may exude from the discharge holes 19. When Pl<P2, there is a risk that a gas may be let into the discharging unit and stop the discharging. Therefore, it is preferable that P1«P2.

A descending air stream (a conveying air stream) 101 is formed in a chamber 61 from a conveying air stream inlet port 64. The liquid droplets 21 discharged from the liquid droplet discharging unit 2 are conveyed downward not only by the gravitational force but also by the conveying air stream 101, collected by a toner collecting unit 62, and stored in a toner storing unit 63.

[Conveying Air Stream] If the jetted liquid droplets contact each other before dried, they merge as one particle (hereinafter, this phenomenon is referred to as merging). In order to obtain solidified particles having a uniform particle size distribution, it is necessary to keep the jetted liquid droplets at a distance from each other. However, the jetted liquid droplets that have a certain initial velocity lose speed after a while due to the air resistance. The particles having lost speed are caught up with by the liquid droplets jetted afterwards, and they merge with each other as a result. Because this phenomenon occurs constantly, the particle size distribution of the particles collected in this state is very poor. In order to prevent merging, it is necessary to solidify and convey the liquid droplets, while preventing the velocity of the liquid droplets from slowing down and the liquid droplets from contacting each other with the conveying air stream 101 to thereby prevent merging. Eventually, the solidified particles are conveyed to the solidified particle collecting unit.

For example, as shown in Fig. 8, by providing a portion of the conveying air stream 101 as a first air stream in the vicinity of the liquid droplet discharging unit in the same direction as the liquid droplet discharging direction, it is possible to prevent the velocity of the liquid droplets from slowing down immediately after the liquid droplets are discharged and thereby prevent merging. Alternatively, the air stream may be transverse to the discharging direction as shown in Fig. 9.

Alternatively, although not illustrated, the air stream may have an angle, and the angle is preferably an angle at which the liquid droplets will be dragged away from the liquid droplet discharging unit. When the merging preventing air stream is supplied transversely to the discharging of the liquid droplets as in Fig. 9, the direction of the merging preventing air stream is preferably a direction in which loca of the liquid droplets when the liquid droplets are conveyed by the air stream will not overlap.

After merging is prevented with the first air stream as described above, the solidified particles may be conveyed to the solidified particle collecting unit with a second air stream.

The velocity of the first air stream is preferably equal to or higher than the velocity at which the liquid droplets are jetted. When the velocity of the merging preventing air stream is lower than the liquid droplet jetting velocity, it is difficult to exert the function of preventing the liquid droplet particles from contacting each other, which is the essential object of the merging preventing air stream.

In terms of characteristics, the first air stream may further be conditioned so as to prevent merging of the liquid droplets, and needs not necessarily be the same as the second air stream. Further, a chemical substance that promotes solidification of the surface of the particles may be mixed in the merging preventing air stream, or may be imparted to the air stream in anticipation of a physical effect.

The conveying air stream 101 is not particularly limited in terms of the state as an air stream, and may be a laminar flow, a swirl flow, or a turbulent flow. The kind of the gas to compose the conveying air stream

101 is not particularly limited, and may be air, or an incombustible gas such as nitrogen. The temperature of the conveying air stream 101 may be adjusted appropriately, and it is preferable that the conveying air stream not undergo temperature fluctuation during production. The chamber 61 may have a unit configured to change the air stream state of the conveying air stream 101. The conveying air stream 101 may be used not only for preventing the liquid droplets 21 from merging but also for preventing them from depositing on the chamber 161.

[Second Drying]

When the toner particles obtained by the drying/collecting unit shown in Fig. 8 contain a large amount of residual solvent, second drying is performed in order to reduce the amount of residual solvent according to necessity. For the second drying, a common publicly-known drying method such as fluid bed drying and vacuum drying may be used. When the organic solvent remains in the toner, not only may toner

characteristics such as heat resistant storage stability, fixability, and charging property change over time, but also the residual solvent may volatilize during fixing by heating, which increases the possibility that the user and peripheral devices will receive adverse influences.

Therefore, sufficient drying is performed.

Examples

The present invention will be explained in greater detail below based on Examples.

It is easy for a person ordinarily skilled in the art to make modifications and alterations to the Examples of the present invention described below and form another embodiment. Such modifications and alterations are included in the present invention, and the explanation to be given below is about the examples of a preferred embodiment of the present invention, and is not to limit the present invention.

Unless otherwise expressly specified, part represents part by mass, and % represents % by mass.

[Example l]

(Production of Toner l)

^■Preparation of Colorant Dispersion Liquid- First, as a colorant, a carbon black dispersion liquid was prepared.

Carbon black (REGAL 400 manufactured by Cabot Corporation) (20 parts) and a pigment dispersant (AJISPER PB821 manufactured by Ajinomoto Fine-Techno Co., Inc.) (2 parts) were primarily dispersed in ethyl acetate (78 parts) with a mixer having a stirring blade. The obtained primary dispersion liquid was dispersed more finely with a strong shearing force with DYNO-MILL, to prepare a secondary dispersion liquid. The obtained liquid was further passed through a polytetrafluoroethylene (PTFE) filter having minute pores of 0.45 μιη (FLORINATE MEMBRANE FILTER FHLP09050 manufactured by Nihon Millipore Inc.), to thereby prepare a carbon black dispersion liquid in which carbon black was dispersed to the extent of a sub-micron domain.

-Preparation of Toner Composition Liquid"

[WAX 1] (20 parts) as a releasing agent and [Polyester Resin A

(Polyester A, with Tg of 60°O] (263.3 parts) as a binder resin were mixed with and dissolved in ethyl acetate (676.7 parts) at 40°C with a mixer having a stirring blade. [WAX l] and the polyester resin A resulted in being dissolved transparently in the ethyl acetate, both without being phase-separated. The above carbon black dispersion liquid (100 parts) was further mixed therein, and they were stirred for 10 minutes, to thereby prepare a toner composition liquid.

Note that [WAX 1] was a synthetic ester wax (manufactured by NOF Corporation) having a melting point of 75.2°C and a

recrystallization temperature of 64.3°C and soluble in ethyl acetate by 4.4% at 40°C.

[Polyester Resin A] was a binder resin made of terephthalic acid, isophthalic acid, and neopentyl glycol and having a weight average molecular weight of 65,000.

The weight average molecular weight Mw of the binder resin was a measurement of a THF soluble content of the binder resin obtained with a GPC (Gel Permeation Chromatography) measuring instrument GPC-150C (manufactured by Waters Corporation). Columns used were KF801 to 807 (manufactured by Shodex Co., Ltd.). A detector used was a RI (Refraction Index) detector.

The boiling point of ethyl acetate was 76.8°C.

■Production of Toner- Liquid droplets of the obtained toner composition liquid were discharged under the conditions below, with a toner producing apparatus of Fig. 11 including a liquid droplet discharging head shown in Fig. 3 as a liquid droplet discharging unit. After liquid droplets were discharged, they were dried and solidified with a liquid droplet solidifying unit using dry nitrogen, collected with a cyclon, and then further dried with a blown air for 48 hours at 35°C/90%RH, and for 24 hours at 40°C/50%RH, to thereby produce toner base particles.

The toner composition liquid and members of the toner producing apparatus to come into contact with the toner composition liquid were controlled to a temperature of 40°C. The toner production was

performed for 6 hours continuously, but the discharge holes were not clogged.

[Toner Production Conditions]

Length L of the longer direction of the liquid column resonance liquid chamber^'- 1.85 mm

Discharge holes: diameter of 8.0 μπι

Drying temperature (nitrogen): 60°C

Driving frequency: 340 kHz

Voltage applied to the piezoelectric element: 10.0 V

Next, hydrophobic silica (H2000 manufactured by Clariant K.K.) (2.0 parts) was externally added to the obtained toner base particles (100.0 parts), with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), to thereby obtain [Toner l].

This [Toner l] was embedded in an epoxy resin, and a slice thereof was made with an ultrasonic microtome. The slice was stained with Ru0₄, and observed with a transmission electron microscope (TEM), to thereby obtain a maximum length Lmax of the wax in a toner particle and a maximum Feret diameter Df of the toner particle containing the wax, with image analysis software IMAGEJ. Further, the content of the wax was obtained as a mass

equivalent of an endothermic amount obtained according to DSC

(Differential Scanning Calorimetry) of [Toner 1]. Furthermore, the amount of the wax present in a region down to a depth of 0.3 μπι from the surface was obtained according to FTIR-ATR (total reflection and infrared absorption spectroscopy).

The particle diameter of the toner was also measured. The results are shown in Table 1.

[Example 2]

(Production of Toner 2)

[Toner 2] was produced in the same manner as in Example 1 above, except that [WAX 2] was used instead of [WAX 1] as a releasing agent and the dissolving temperature was set to 50°C in the preparation of the toner composition liquid of Example 1, and the toner composition liquid and the members of the toner producing apparatus to come into contact with the toner composition liquid were controlled to a

temperature of 50°C. The results of the same evaluations as in Example 1 on [Toner 2] are shown in Table 1 below.

[WAX 2] was a synthetic amide wax (manufactured by NOF Corporation) having a melting point of 67.4°C and a recrystallization temperature of 60.5°C and soluble in ethyl acetate by 9.5% at 50°C.

[Example 3]

(Production of Toner 3)

[Toner 3] was produced in the same manner as in Example 1 above, except that [WAX 3] was used instead of [WAX 1] as a releasing agent in the preparation of the toner composition liquid of Example 1. The results of the same evaluations as in Example 1 on [Toner 3] are shown in Table 1 below.

[WAX 3] was a synthetic ester wax (manufactured by NOF Corporation) having a melting point of 71.7°C and a recrystallization temperature of 64.5°C and soluble in ethyl acetate by 3.9% at 40°C.

[Example 4]

(Production of Toner 4)

[Toner 4] was produced in the same manner as in Example 1 above, except that [WAX 4] was used instead of [WAX l] as a releasing agent in the preparation of the toner composition liquid of Example 1. The results of the same evaluations as in Example 1 on [Toner 4] are shown in Table 1 below.

[WAX 4] was a synthetic ester wax (manufactured by Nippon Seiro Co., Ltd.) having a melting point of 70.3°C and a recrystallization temperature of 64.1°C and soluble in ethyl acetate by 3.6% at 40°C.

[Example 5]

(Production of Toner 5)

[Toner 5] was produced in the same manner as in Example 4 above, except that the drying temperature was changed from 60°C to 40°C, and a nitrogen stream in which a relative humidity of ethyl acetate was 12% was used in the production of the toner of Example 4. The results of the same evaluations as in Example 1 on [Toner 5] are shown in Table 1 below.

[Example 6] (Production of Toner 6)

[Toner 6] was produced in the same manner as in Example 4 above, except that the drying temperature was changed from 60°C to 40°C, and a nitrogen stream in which a relative humidity of ethyl acetate was 37% was used in the production of the toner of Example 4. The results of the same evaluations as in Example 1 on [Toner 6] are shown in Table 1 below.

[Example 7]

(Production of Toner 7)

[Toner 7] was produced in the same manner as in Example 1 above, except that [WAX 5] was used instead of [WAX 1] as a releasing agent, toluene was used instead of ethyl acetate as a solvent,

[Styrene/Acrylic Resin A] (Styrene Acrylic A) was used instead of

[Polyester Resin A] as a binder resin, the dissolving temperature was set to 35°C, the toner composition liquid and the members of the toner producing apparatus to come into contact with the toner composition liquid were controlled to a temperature of 35°C, and the drying

temperature was set to 66°C in the preparation of the toner composition liquid of Example 1. The results of the same evaluations as in Example 1 on [Toner 7] are shown in Table 1 below.

[Styrene -Acrylic Resin A] was a copolymer resin made of styrene/butyl acrylate, and had a glass transition temperature Tg of 62°C.

[WAX 5] was a paraffin wax (HNP-9 manufactured by Nippon

Seiro Co., Ltd.) having a melting point of 74.1°C and a recrystallization temperature of 70.1°C, and soluble in toluene by 4% at 35°C. [Example 8]

(Production of Toner 8)

[Toner 8] was produced in the same manner as in Example 1 above, except that [WAX 6] was used instead of [WAX l] as a releasing agent, and the dissolving temperature was set to 30°C in the production of the toner of Example 1. The results of the same evaluations as in Example 1 on [Toner 8] are shown in Table 1 below.

[WAX 6] was a synthetic amide wax (manufactured by NOF Corporation) having a melting point of 62.6°C and a recrystallization temperature of 52.7°C, and soluble in ethyl acetate by 2.9% at 30°C. [Example 9]

(Production of Toner 9)

[Toner 9] was produced in the same manner as in Example 1 above, except that the drying temperature was changed from 60°C to 45°C, and a nitrogen stream in which a relative humidity of ethyl acetate was 23% was used in the production of the toner of Example 1. The results of the same evaluations as in Example 1 on [Toner 9] are shown in Table 1 below.

[Example 10]

(Production of Toner 10)

[Toner 10] were produced in the same manner as Example 2 above, except that the drying temperature was changed from 60°C to

40°C, and a nitrogen stream in which a relative humidity of ethyl acetate was 20% was used in the production of the toner of Example 2. The results of the same evaluations as in Example 1 on [Toner 10] are shown in Table 1 below.

[Example 11]

(Production of Toner 11)

[Toner 11] was produced in the same manner as in Example 3 above, except that the drying temperature was changed from 60°C to 40°C, and a nitrogen stream in which a relative humidity of ethyl acetate was 18% was used in the production of the toner of Example 3. The results of the same evaluations as in Example 1 on [Toner 11] are shown in Table 1 below.

[Comparative Example l]

(Production of Toner 12)

[Toner 12] was produced in the same manner as in Example 1 above, except that the drying temperature was changed from 60°C to 55°C in the production of the toner of Example 1. The results of the same evaluations as in Example 1 on [Toner 12] are shown in Table 1 below.

[Comparative Example 2]

(Production of Toner 13)

[Toner 13] was produced in the same manner as in Example 5 above, except that the relative humidity was changed from 12% to 8% in the production of the toner of Example 5. The results of the same evaluations as in Example 1 on [Toner 13] are shown in Table 1 below.

[Comparative Example 3]

(Production of Toner 14)

Toner collection was attempted in the same manner as in Example 5 above, except that the relative humidity was changed from 12% to 45% in the production of the toner of Example 5. However, blocking occurred in the collection container, and no evaluable toner could be obtained.

[Comparative Example 4]

(Production of Toner 15)

As in Example 2 above, a toner composition liquid was prepared as a dispersion, without [WAX 2] being dissolved in ethyl acetate.

-Preparation of Wax Dispersion Liquid-

A vessel equipped with a stirring blade and a thermometer was charged with [WAX 2] (20 parts) and ethyl acetate (80 parts), and they were heated to 60°C and stirred for 20 minutes to dissolve [WAX 2], and after this, quenched in order to deposit [WAX 2] as fine particles. The obtained [WAX 2 Dispersion Liquid] was dispersed more finely with STAR MILL LMZ06 (manufactured by Ashizawa Finetech Ltd.) filled with 0.3 μιηφ zirconia beads at a rotation speed of 1,800, to thereby prepare [WAX 2 Dispersion Liquid] in which the average particle diameter of the wax was 0.3 μπι, and the maximum particle diameter thereof was 0.8 μπι. The particle diameters of the wax were measured with NPA150 manufactured by Micro Track Co., Ltd.

-Preparation of Toner Composition Liquid-

[Polyester Resin A] (263.3 parts) as a binder resin was dissolved in ethyl acetate (636.7 parts), and after this, [WAX 2 Dispersion Liquid]

(100 parts) and the carbon black dispersion liquid (100 parts) were mixed therein at 25°C with a mixer having a stirring blade, to thereby prepare a toner composition liquid.

Using this toner composition liquid, [Toner 15] was produced in the same manner as in Example 2, except that the dissolving

temperature was changed from 50°C to 30°C, and the drying temperature was changed from 60°C to 40°C. The results of the same evaluations as in Example 1 on [Toner 15] are shown in Table 1 below.

■Production of Carrier-

Silicone (organo straight silicone) 100 parts

Toluene 100 parts

Y"(2-aminoethyl)aminopropyl trimethoxysilane 5 parts

Carbon black 10 parts

The mixture of those above was dispersed with a homomixer for 20 minutes, to thereby prepare a coating layer forming liquid. This coating layer forming liquid was applied to the surface of spherical magnetite (1,000 parts) having a particle diameter of 50 μπι with a fluid bed coater, to thereby obtain a magnetic carrier.

■Production of Developer-

The obtained toners 1 to 13 and 15 (4 parts) and the magnetic carrier (96.0 parts) were mixed with a ball mill, to thereby produce developers 1 to 13 and 15 of Examples 1 to 11 and Comparative Examples 1, 2, and 4.

^■Results of Evaluation- Evaluations of a cold offset property, a hot offset property, a toner filming property (filming resistance), an adherence property, and image stability were performed with the developers 1 to 13 and 15 according to the evaluation procedures described below. The results of the

evaluations are shown in Table 2 below. The procedure for evaluating the particle diameter and particle size distribution of the toner is also described below.

«Particle Diameter, Particle Size Distribution, Most Frequent Diameter, and Second Peak of Toner»

The volume average particle diameter (Dv) and the number average particle diameter (Dn) of the toner of the present invention are measured with a particle diameter measuring instrument

("MULTISIZER III" manufactured by Beckman Coulter Inc.) at an aperture diameter of 50 μιη. After the volume and number of the toner particles or the toner are measured, a volume distribution and a number distribution are calculated. From the obtained distributions, the volume average particle diameter (Dv) and the number average particle diameter (Dn) can be obtained. A value Dv/Dn, which is obtained by dividing the volume average particle diameter (Dv) of the toner by the number average particle diameter (Dn) thereof, is used as the indicator of the particle size distribution. This value is 1 when the toner is completely monodisperse, and the greater this value, the broader the distribution is. The most frequent diameter and the second peak are also measured with the same instrument.

«Cold Offset Property»

With a commercially available copier IMAGIO NEO C600 manufactured by Ricoh Company Limited, the developer is deposited on an A4-size sheet (T6000 70W, long grain, manufactured by Ricoh

Company Limited) in an amount of 0.85 mg/cm² as a rectangular image of 3 cm x 5 cm, at a position of 5 cm from the leading end of the sheet, to thereby make a toner sample. Then, the image is fixed at a liner velocity of 300 m, with the temperature of the fixing member controlled to 120°C constantly (the weight of the toner is calculated from the weights of the sheet before and after the image is output).

Presence or absence of offset is evaluated visually by an evaluator at 120°C, and judged based on criteria.

A: No cold offset occurs.

B: Minute cold offset is observed at some positions, but the number of them is 3 or less.

C- Minute cold offset occurs at more than 3 positions.

D: Cold offset occurs.

«Hot Offset Property»

The developer is set in a commercially available copier IMAGIO

NEO C600 manufactured by Ricoh Company Limited, and a rectangular image of 3 cm x 5 cm is deposited on an A4^_size sheet (T6000 70W, long grain, manufactured by Ricoh Company Limited) in an amount of 0.85 mg/cm² at a position of 5 cm from the leading end of the sheet, to thereby make a toner sample. Such images are output, with the fixing

temperature varied from lower temperatures to higher temperatures.

The temperature at which glossiness of the image is low or an offset image is observed in the image is regarded as an offset occurrence temperature. When the offset occurrence temperature is 200°C or higher, the evaluation is B. When the offset occurrence temperature is lower than 200°C, the evaluation is D.

«Toner Filming»

With each of the produced developers used in a tandem color image forming apparatus (IMAGIO NEO C600 manufactured by Ricoh Company Limited), a chart with an image occupation rate of 20% is output on 200,000 sheets with the toner concentration controlled such that the image density will be 1.4+0.2, and after this, a comparison with the initial value of an amount of static buildup of the electrophotographic toner is made, as an amount of change in the amount of static buildup (μο/g), namely (an amount of decrease in the amount of static buildup after a run of 200,000 sheets / the amount of static buildup at an initial stage of the run), and this value is evaluated based on the criteria below. The amount of static buildup is measured according to a blow-off procedure.

[Evaluation Criteria]

A: Lower than 15%

B: 15% or higher but lower than 30%

C: 30% or higher but lower than 50%

D: 50% or higher

Filming of a toner over an electrophotographic carrier causes a change in the composition of the outermost surface of the

electrophotographic carrier, which results in decrease in the amount of static buildup. It is judged that the smaller this change in the amount of static buildup before and after the run, the lower the degree of filming of the toner over the electrophotographic carrier.

«Evaluation of Image Stability»

The developer is set in a commercially available copier (IMAGIO NEO 455 manufactured by Ricoh Company Limited), and a continuous running test is performed on 50,000 sheets of TYPE 6000 PAPER manufactured by Ricoh Company Limited, with a printing rate of an image occupation rate of 7%, and the image qualities (image density, fine line reproducibility, and background smear) of the 50,000th sheet are evaluated based on the criteria below.

B: The 50,000th sheet is a favorable image comparable to earlier images.

C: Any of the evaluation items of image density, fine line reproducibility, and background smear changes from earlier images, but the change is acceptable.

D: Any of the evaluation items of image density, fine line reproducibility, and background smear changes apparently from earlier images, and the change is not acceptable.

«Adherence Resistance»

With each of the produced developers used in a tandem color image forming apparatus (IMAGIO NEO C600 manufactured by Ricoh Company Limited), 10,000 blank sheets are printed out, and then the photoconductor and the blank sheets are observed.

The experiment is performed at a temperature of 30°C and a relative humidity of 80%.

[Evaluation Criteria] A: Toner deposition is observed neither on the blank sheets nor on the photoconductor.

B: Deposition is not observed on the blank sheets, whereas thin toner deposition is observed on the photoconductor when seen from an angle but can be removed with a rag, and adherence is not observed.

C: Thin toner deposition is observed on the photoconductor when seen from an angle and cannot be removed even by being scrubbed with a rag, whereas toner deposition is not observed on the blank sheets.

^~D- Apparent toner deposition is observed on both of the

photoconductor and the blank sheets, and cannot be removed even by being scrubbed with a rag.

Table 1

Table 2

Aspects of the present invention are as follows, for example.

<1> A toner, including at least

a binder resin,^" and

a releasing agent,

<2> The toner according to <1>,

wherein the releasing agent has a melting point of 65°C or higher. <3> The toner according to <1> or <2>,

wherein the releasing agent is a wax,

wherein a content of the wax, as a mass equivalent of an

endothermic amount of the wax obtained according to a DSC (Differential Scanning Calorimetry) procedure, is from 1% by mass to 20% by mass relative to a whole of the toner, and

wherein an amount of the wax present in a region down to a depth of 0.3 μηι from a surface of the toner, obtained according to a FTIR-ATR (total reflection and infrared absorption spectroscopy) procedure, is 0.1% by mass or greater but less than 4% by mass.

<4> The toner according to any one of <1> to <3>,

wherein the toner has a volume average particle diameter of from

1 μπι to 8 μπι, and a particle size distribution (volume average particle diameter/number average particle diameter) ranging from 1.00 to 1.15.

<5> The toner according to any one of <1> to <4>,

wherein the toner has at least a second peak particle diameter that is from 1.21 to 1.31 times as large as a most frequent diameter thereof in a volume -basis particle size distribution thereof.

<6> A toner producing method, including-^'

forming liquid droplets by discharging a toner composition liquid obtained by dissolving or dispersing at least a binder resin and a releasing agent in a solvent; and

solidifying the liquid droplets to form fine particles,

wherein the binder resin and the releasing agent is dissolved in the toner composition liquid without being phase-separated,

wherein a temperature of an atmosphere during the solidification of the liquid droplets is [Tc-5]°C or higher, where Tc(°C) is a

recrystallization temperature of the releasing agent obtained according to a DSC procedure, and

wherein the binder resin and the releasing agent are

phase-separated in the fine particles obtained from the solidification of the liquid droplets.

<7> A toner producing method, including:

solidifying the liquid droplets to form fine particles,

wherein the binder resin and the releasing agent are dissolved in the toner composition liquid without being phase-separated,

wherein a temperature of an atmosphere during the solidification of the liquid droplets is lower than a recrystallization temperature of the releasing agent obtained according to a DSC procedure, and a relative humidity of the solvent of the toner composition liquid in the atmosphere during the solidification of the liquid droplets is from 10% to 40%, and wherein the binder resin and the releasing agent are

<8> The toner producing method according to <6> or <7>,

wherein a temperature of the toner composition liquid under the temperature of the atmosphere during the solidification of the liquid droplets is lower than [Tb-20]°C, where Tb(°C) is a boiling point of the solvent.

<9> A two-component developer, including at least:

the toner according to any one of <1> to <5>; and

a carrier.

<10> An image forming method, including at least:

electrically charging a surface of an electrostatic latent image bearing member,^'

exposing the electrically charged surface of the electrostatic latent image bearing member to light to form an electrostatic latent image,^' developing the electrostatic latent image with a developer to form a visible image,^'

transferring the visible image onto a recording medium, and fixing a transferred image transferred onto the recording medium thereon,

wherein the developer is the developer according to <9>. <11> An image forming apparatus, including at least:

an electrostatic latent image bearing member;

a charging unit configured to electrically charge a surface of the electrostatic latent image bearing member;

an exposing unit configured to expose the electrically charged surface of the electrostatic latent image bearing member to light to form an electrostatic latent image;

a developing unit configured to develop the electrostatic latent image with a developer to form a visible image;

a transfer unit configured to transfer the visible image onto a recording medium; and

a fixing unit configured to fix a transferred image transferred onto the recording medium thereon,

wherein the developer is the developer according to <9>.

Reference Signs List

l: toner producing apparatus

2- liquid droplet discharging unit

6÷ toner composition liquid supply port

T- toner composition liquid flow path

8^ toner composition liquid discharge port

9: elastic plate

10^ liquid column resonance liquid droplet discharging unit 11: liquid column resonance liquid droplet discharging unit 12: air stream flow path 13: raw material container

14: toner composition liquid

15: liquid circulating ump

16: liquid supply pipe

17: common liquid supply path 18: liquid column resonance flow path 19: discharge hole

0: vibration generating unit

21: liquid droplet

22: liquid returning pipe

60: drying/collecting unit

61^: chamber

62: toner collecting unit

63: toner storing unit

64: conveying air stream inlet port 65: conveying air stream outlet port lOOl: toner particles

1002^"· releasing agent

Pi: liquid pressure gauge

P2: chamber inner pressure gauge

Claims

1. A toner, comprising:

a binder resini and

a releasing agent,

wherein a maximum length Lmax of the releasing agent in a toner particle is 1.1 or greater times as large as a maximum Feret diameter Df of the toner particle that comprises the releasing agent.

2. The toner according to claim 1,

wherein the releasing agent has a melting point of 65°C or higher.

3. The toner according to claim 1 or 2,

wherein the releasing agent is a wax,

wherein a content of the wax, as a mass equivalent of an

wherein an amount of the wax present in a region down to a depth of 0.3 μπι from a surface of the toner, obtained according to a FTIR-ATR (total reflection and infrared absorption spectroscopy) procedure, is 0.1% by mass or greater but less than 4% by mass.

4. The toner according to any one of claims 1 to 3,

wherein the toner has a volume average particle diameter of from

1 μκι to 8 μιη, and a particle size distribution (volume average particle diameter/number average particle diameter) ranging from 1.00 to 1.15.

5. The toner according to any one of claims 1 to 4, wherein the toner has at least a second peak particle diameter that is from 1.21 to 1.31 times as large as a most frequent diameter thereof in a volume-basis particle size distribution thereof.

6. A toner producing method, comprising:

solidifying the liquid droplets to form fine particles,

wherein a temperature of an atmosphere during the solidification of the liquid droplets is [Tc-5](°C) or higher, where Tc(°C) is a

wherein the binder resin and the releasing agent are

7. A toner producing method, comprising-^'

solidifying the liquid droplets to form fine particles,

8. The toner producing method according to claim 6 or 7,

9. A two-component developer, comprising:

the toner according to any one of claims 1 to 5, and

a carrier.

10. An image forming method, comprising:

electrically charging a surface of an electrostatic latent image bearing member!

exposing the electrically charged surface of the electrostatic latent image bearing member to light to form an electrostatic latent image;

developing the electrostatic latent image with a developer to form a visible image,^'

transferring the visible image onto a recording medium,^' and fixing a transferred image transferred onto the recording medium thereon, wherein the developer is the developer according to claim 9.

11. An image forming apparatus, comprising:

an electrostatic latent image bearing member;

a charging unit configured to electrically charge a surface of the electrostatic latent image bearing member,^'

a transfer unit configured to transfer the visible image onto a recording medium,^' and

wherein the developer is the developer according to claim 9.