JP2002091066A - Electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner consisting of spheric or nearly spheric polyester resin, with which fixing without using an offset preventing liquid, namely a so-called oil-less system is made possible as the method of heat roller fixing and that developed images with excellent quality can be obtained. SOLUTION: The electrostatic charge image developing toner is prepared by the method for manufacturing resin particles encapsulating at least a coloring agent and release agent in a binder resin by using polyester resin (I) containing acid groups as the binder resin and mixing a mixture containing at least the binder resin, coloring agent, release agent and organic solvent with a water- based medium in the presence of a base to emulsify. The release agent incorporated into the mixture is prepared as a dispersion liquid of the release agent obtained by mixing the release agent with a dispersant in an organic solvent and further pulverizing and/or dispersing the mixture in a medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image, which is suitably used for an electrophotographic copying machine, a printer, a facsimile and the like, and is also used for a toner jet printer and the like.

[0002]

2. Description of the Related Art In recent years, in electrophotographic copiers, printers, and fax machines, toners have been used to further improve the quality of printed images or to reduce machine cost, downsizing, power saving, and resource saving. The following needs are increasing. (1) Toner size reduction and spheroidization for improving the resolution and gradation of printed images, thinning the toner layer, reducing the amount of waste toner, and reducing the toner consumption per page. (2) Lowering the fixing temperature to reduce power consumption (3) Oil-less fixing for simplification of machines, etc. (4) Improvement of hue, transparency and gloss in full-color images (5) Human health Reduction of VOC (volatile organic compound) at the time of fixing which may adversely affect the image quality.

[0003] It is basically possible to reduce the particle size of the powder toner by a pulverization method which has been used for a long time.
As the particle size decreases, the ratio of a release agent such as a colorant or wax exposed on the surface of the toner particles increases, so that charge control becomes difficult. Due to the irregular shape of the toner particles, powder fluidity deteriorates. In addition, problems such as an increase in the energy cost required for the production occur, and it is practically difficult to sufficiently satisfy the above-mentioned needs with the irregular toner by the pulverization method.

[0004] From such a background, development of spherical toners by a polymerization method or an emulsification dispersion method has hitherto been actively carried out. Various methods are known for the toner by the polymerization method. Among them, an aqueous medium containing a monomer, a polymerization initiator, a colorant, a charge control agent, and the like is uniformly dissolved and dispersed, and the dispersion medium contains a dispersion stabilizer. Add while stirring
A suspension polymerization method is widely used in which after forming oil droplets, the temperature is raised and a polymerization reaction is performed to obtain toner particles. According to the polymerization method, although there is no problem in reducing the particle size and spheroidization of the toner particles, since the main component of the binder resin is limited to a vinyl polymer that can be radically polymerized, it is suitable for color toners and the like. Toner particles made of polyester resin or epoxy resin,
It cannot be produced by a suspension polymerization method. Further, in the polymerization method, there is a problem that it is difficult to reduce VOC (volatile organic compound composed of an unreacted monomer and the like), and improvement thereof is desired.

On the other hand, a method for producing a toner by the emulsification dispersion method is as follows.
JP-A-5-66600 and JP-A-8-21655
As disclosed in Japanese Unexamined Patent Application Publication No. H10-163, a method in which a mixture of a binder resin and a colorant and the like is mixed with an aqueous medium and emulsified to obtain toner particles. In addition to being able to easily cope with diameter and spheroidization, the range of choice of the type of binder resin is wider than in the polymerization method.
It has the advantages that the OC can be easily reduced and the concentration of the colorant and the like can be arbitrarily changed from a low concentration to a high concentration.

[0006] As a binder resin for a toner having a relatively low fixing temperature and which tends to be sharply melted at the time of fixing to make the image surface smooth, a polyester resin is preferable to a styrene-acrylic resin. It is well known that a polyester resin having excellent flexibility is preferable. However, as described above, the polymerization method cannot produce toner particles containing a polyester resin as a main component of the binder resin. Therefore, in recent years, attention has been focused on producing a spherical to substantially spherical small particle size toner using a polyester resin as a binder resin by an emulsification dispersion method.

[0007]

However, in the conventional polyester resin toner obtained by the emulsification dispersion method, since the binder resin is a relatively low-molecular-weight linear resin, an offset phenomenon is apt to occur, so that this phenomenon is prevented. For,
It was necessary to apply an anti-offset liquid such as silicone oil to the fixing heat roll.

However, applying the anti-offset liquid to the fixing heat roll not only has a problem that the maintenance becomes complicated, but also causes a transfer of the silicone oil or the like to the printing paper or the OHP sheet. Problems such as hindrance and stickiness of the oil are caused.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a so-called oilless system which enables fixing without using an offset prevention liquid as a heat roller fixing system. In addition, it is an object of the present invention to provide a spherical to substantially spherical toner for developing an electrostatic charge image, which is made of a polyester resin and can provide a high quality developed image.

[0010]

Means for Solving the Problems As a result of intensive studies on the release agent contained in the binder resin, the present inventor has found that the coagulation of the release agent is prevented and the dispersibility of the release agent is improved, thereby improving the offset. They have found that they can be suppressed and completed the present invention.

That is, the toner for developing an electrostatic image of the present invention comprises an acidic group-containing polyester resin (I) as a binder resin and at least the binder resin, a colorant, a release agent and an organic solvent. The mixture is emulsified by mixing with an aqueous medium in the presence of a base, and for developing an electrostatic image obtained by a production method of forming resin particles containing at least a colorant and a release agent in the binder resin. In the toner, the form of the release agent contained in the mixture is a release agent obtained by mixing the release agent and the dispersant into an organic solvent and mixing and further pulverizing and / or dispersing the mixture with a medium. Is a solution to the above problem.

The release agent is preferably a release agent selected from the group consisting of hydrocarbon waxes such as polypropylene wax, polyethylene wax and Fischer-Tropsch wax, and synthetic ester waxes.

The acidic group-containing polyester resin (I) has a (A) T1 / 2 temperature of 80 ° C. or more and 120 ° C. or less measured by a constant load extrusion type capillary rheometer,
A straight-chain polyester resin having a glass transition temperature Tg of 40 ° C. or more and 75 ° C. or less, (B) a T1 / 2 temperature of 120 ° C. with a constant load extrusion type capillary rheometer exceeding 21 ° C.
0 ° C. or less, and the glass transition temperature Tg is 40 ° C. or more, 7
A mixture of a crosslinked polyester resin having a temperature of 5 ° C. or lower, wherein the weight ratio of the resin (A) and the resin (B) is (A) /
(B) = 20/80 to 80/20, and when T1 / 2 temperatures are T1 / 2 (A) and T1 / 2 (B), respectively, 20 ° C. <T1 / 2 (B) −T1 / 2 (A) It is preferable that the relation of ≦ 120 ° C. is satisfied.

The dispersant is preferably a polyester resin (II), and the polyester resin (II) is preferably an acidic group-containing linear polyester resin.

The average circularity defined by the following equation is
It is preferably a spherical shape of 0.97 or more to a substantially spherical shape. Average circularity = (perimeter of a circle having the same area as the projected area of the particle) /
(Perimeter of particle projection image)

Hereinafter, the present invention will be described in detail. The acidic group-containing polyester resin used as a binder resin of the electrostatic image developing toner of the present invention is referred to as a first polyester resin in the present invention, that is, a polyester resin (I) in the present specification, and a dispersion resin described later. This is distinguished from the second polyester resin (II) suitably used as an agent. This acidic group-containing polyester resin (I)
Is synthesized by, for example, dehydration condensation of a polybasic acid and a polyhydric alcohol.

Examples of the polybasic acids include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, and naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, Aliphatic carboxylic acids such as alkenylsuccinic anhydride and adipic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid; These polybasic acids can be used alone or in combination of two or more. Among these polybasic acids, it is preferable to use aromatic carboxylic acids.

Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, and pentaerythritol; cyclohexanediol And alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A; and aromatic diols such as ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A. These polyhydric alcohols can be used alone or in combination of two or more. Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.

Here, the obtained polyester resin (I)
May contain a carboxyl group as an acidic group, a polycondensation reaction between a polyvalent carboxylic acid and a polyhydric alcohol may be performed such that the carboxyl group remains. Further, as a method of introducing a carboxyl group into the polyester resin to contain an acidic group, a linear or branched polyester resin having a hydroxyl group, a maleic anhydride, phthalic anhydride, an acid anhydride-containing compound such as trimellitic anhydride Is added. It is also possible to employ a method in which a tetracarboxylic dianhydride such as pyrimellitic anhydride is reacted with a hydroxyl group-containing polyester resin, preferably a linear polyester resin, to introduce a carboxyl group and simultaneously elongate the chain. Further, a carboxyl group can be introduced into the polyester resin by grout polymerization of a polymerizable monomer containing a carboxyl group.

Incidentally, in the acidic group-containing polyester resin (I) in the present invention, the acidic group may be a phosphoric acid group or a sulfonic acid group other than the above-mentioned carboxyl group. By having such an acidic group, the polyester resin (I) increases hydrophilicity by neutralization,
A so-called self-water-dispersible resin that disperses in an aqueous medium (water or a liquid medium containing water as a main component) without using an emulsifier or a dispersion stabilizer.

Further, to the polyester resin (I) thus obtained, a monocarboxylic acid and / or a monoalcohol is further added to esterify the hydroxyl group and / or the carboxyl group at the polymerization terminal, and the polyester resin The acid value of (I) can also be adjusted. Monocarboxylic acids used for such purposes include, for example, acetic acid,
Examples thereof include acetic anhydride, benzoic acid, trichloroacetic acid, trifluoroacetic acid, and propionic anhydride. Further, as the monoalcohol, for example, methanol, ethanol,
Propanol, octanol, 2-ethylhexanol, trifluoroethanol, trichloroethanol,
Hexafluoroisopropanol, phenol and the like can be mentioned.

The polyester resin (I) can be produced by subjecting the above-mentioned polyhydric alcohol and polyvalent carboxylic acid to a condensation reaction according to a conventional method. For example, the polyhydric alcohol and the polyhydric carboxylic acid are blended in a thermometer, a stirrer, a reaction vessel equipped with a falling condenser, and heated at 150 to 250 ° C. in the presence of an inert gas such as nitrogen.
The by-product low-molecular compound is continuously removed from the reaction system, and the reaction is stopped when a predetermined physical property value is reached, followed by cooling, whereby a desired reactant can be obtained.

The synthesis of the polyester resin (I) can be carried out by adding a catalyst. As the esterification catalyst to be used, for example, dibutyltin dilaurate,
Examples include organic metals such as dibutyltin oxide and metal alkoxides such as tetrabutyl titanate. When the carboxylic acid component used is a lower alkyl ester, a transesterification catalyst can be used. Examples of the transesterification catalyst include metal acetates such as zinc acetate, lead acetate and magnesium acetate; metal oxides such as zinc oxide and antimony oxide; and metal alkoxides such as tetrabutyl titanate. The amount of the catalyst to be added is preferably in the range of 0.01 to 1% by weight based on the total amount of the raw materials.

In such a polycondensation reaction, particularly for producing a crosslinked polyester resin, a polybasic acid having three or more carboxyl groups in one molecule or an anhydride thereof, and / or one molecule A polyhydric alcohol having three or more hydroxyl groups therein may be used as an essential synthesis raw material.

The polyester resin (I) thus obtained may be composed of one kind of polyester resin. However, the polyester resin (A) and the linear polyester resin (A) may be used under the following conditions. It is more preferable to use a mixture with the crosslinked polyester resin (B). That is, as the straight-chain polyester resin (A), the T1 / 2 temperature measured by a constant load extrusion type capillary rheometer was 80%.
C. to 120 ° C. and a glass transition temperature Tg of 4
As a crosslinked polyester resin (B) having a T1 / 2 temperature of from 120 ° C. to 210 ° C. and a glass transition temperature Tg of 40 ° C. to 75 ° C. C. or more and 75 ° C. or less, and the weight ratio of the linear polyester resin (A) to the crosslinked polyester resin (B) is (A) /
(B) = 20 / 80-80 / 20, and T1 / 2
Assuming that the temperatures are T1 / 2 (A) and T1 / 2 (B), those having a relationship of 20 ° C. <T1 / 2 (B) −T1 / 2 (A) ≦ 120 ° C. are used.

Here, the T1 / 2 temperature measured by the constant load extrusion type capillary rheometer is determined by using a flow tester CFT-500 manufactured by Shimadzu Corporation in the present invention. This flow tester fills a cylinder 2 having a nozzle 1 with a nozzle diameter D of 1.0 mmΦ and a nozzle length (depth) L of 1.0 mm as shown in FIG. 10k per unit area (1cm ² ) from the side opposite to 1
The load S is obtained by measuring the stroke S of the load surface 4 (the sink value of the load surface 4) when the load is applied at a rate of 6 ° C./min. That is, the relationship between the temperature and the stroke S is determined as shown in FIG. 1 (b), and when the flow of the resin 3 from the nozzle 1 starts, the stroke S suddenly increases and the curve rises. Let the temperature be Tfb and the resin 3 from nozzle 1
Tend is the temperature when the outflow of the water is almost finished and the curve is bent
And Then, the stroke Sfb at the time of Tfb and Tend
The temperature at the time of S1 / 2, which is an intermediate value with the stroke Send at the time of, is defined as the T1 / 2 temperature. In the present invention, the glass transition temperature Tg is 10 per minute by the second run method using a differential scanning calorimeter DSC-50 manufactured by Shimadzu Corporation.
It is a value obtained by measuring at a heating rate of ° C.

Both the linear polyester resin (A) and the crosslinked polyester resin (B) preferably have a glass transition temperature Tg of 40 ° C. or more and 75 ° C. or less, because the glass transition temperature Tg is 40 ° C. When the glass transition temperature is less than 75 ° C., the obtained toner tends to cause blocking (a phenomenon in which toner particles are aggregated and clumped) during storage or in a developing machine. This is because the fixing temperature of the toner tends to increase. Note that the linear polyester resin (A) indicates a resin that is soluble in tetrahydrofuran containing no crosslinking agent component, and the crosslinked polyester resin (B) indicates a resin that has a component insoluble in tetrahydrofuran.

As described above, by using the linear polyester resin (A) and the crosslinked polyester resin (B) having the above relationship as the polyester resin serving as the binder resin, the obtained toner has better fixability. Is preferable. In general, a low-molecular-weight, low-viscosity linear polyester resin (A) is blended with a high-molecular-weight, high-viscosity cross-linked polyester resin (cross-linked polyester resin) (B). Also, it is practical and preferable in the production of resin.

In the toner for developing an electrostatic image of the present invention, the releasing agent is selected from the group consisting of hydrocarbon waxes such as polypropylene wax, polyethylene wax and Fischer-Tropsch wax, and synthetic ester waxes. Wax is preferably used.

Although the melting point of the wax used is not particularly limited, it is preferably 150 ° C. from the viewpoint of offset resistance.
The temperature is preferably in the range of 50 to 120 ° C. from the viewpoint of low-temperature fixability and storage stability. Such a wax is used after being prepared in a dispersion liquid as described later in the production of the toner. Further, the wax is preferably dispersed in the toner particles, and is preferably dispersed with a particle diameter of 3 μm or less on average, and preferably about 1 μm or less on average. The content of the wax is preferably in the range of 1 to 40% by weight based on the toner.
If it is less than 1% by weight, the releasability tends to be insufficient, and
If the content exceeds 0% by weight, the wax is likely to be exposed on the surface of the toner particles, and the chargeability and the storage stability are likely to be reduced.

The colorant used in the toner for developing an electrostatic image of the present invention is not particularly limited, and any known and commonly used colorant can be used, and various pigments are more preferably used. Examples of the black pigment include carbon black, cyanine black, aniline black, ferrite, and magnetite. In addition, a mixture of the following chromatic pigments so as to be black can also be used.

As the yellow pigment, for example, yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, loess, titanium yellow, naphthol yellow S, Hansa yellow 10G, Hansa yellow 5G, Hansa yellow G, Hansa yellow GR, Hansa yellow A, Hansa Yellow RN, Hansa Yellow R, Pigment Yellow L, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow GR,
Permanent Yellow NCG, Vulcan First Yellow 5G, Vulcan First Yellow R, Quinoline Yellow Lake, Anslagen Yellow 6GL, Permanent Yellow FGL, Permanent Yellow H10G,
Permanent yellow HR, anthrapyrimidine yellow, other isoindolinone yellow, chromophtal yellow, novo palm yellow H2G, condensed azo yellow, nickel azo yellow, copper azomethine yellow and the like.

Examples of the red pigment include red lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indaslen brilliant orange RK, indaslen brilliant orange GK, benzidine orange G, permanent red 4R, and permanent red BL. , Permanent red F
5RK, Risor Red, Pyrazolone Red, Watching Red, Lake Red C, Lake Red D, Brilliant Carmine 6B, Brilliant Carmine 3B, Rhodamine Lake B, Alizarin Lake, Permanent Carmine FBB, Verinone Orange, Isoindolinone Orange, Ansuanthrone Orange Pyranthrone orange, quinacridone red, quinacridone magenta, quinacridone scarlet, perylene red and the like.

Examples of blue pigments include cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, fanatone blue 6G, Victoria blue lake, metal-free phthalocyanine blue, copper phthalocyanine blue, fast sky blue, and induslen blue RS. , Indaslen Blue BC, Indico and the like. The amount of these colorants used is
The range of 1 to 50 parts by weight per 0 parts by weight is preferable, and
A range of 15 parts by weight is particularly preferred.

In order to reduce the particle size of the toner and maintain good triboelectric charging performance, the colorant and the like must not be exposed on the surface of the toner particles. It is effective to make the toner structure as described. The deterioration of the chargeability due to the decrease in the particle size of the toner is also caused by the fact that a part of the contained colorant and other additives (usually wax and charge control agent) is exposed on the surface of the toner particles. That is, even if the content (% by weight) of the colorant or the like is the same, the surface area of the toner particles increases due to the reduction in the particle size, and the ratio of the colorant or wax exposed on the surface of the toner particles increases. As a result, the composition of the surface of the toner particles is largely changed, and the frictional charging performance of the toner particles is largely changed, so that it is difficult to obtain an appropriate charging property.

The toner of the present invention contains at least a colorant and a wax in a binder resin, and by having such a structure, a good printed image can be obtained. Whether the colorant or wax is not exposed on the surface of the toner particles can be easily determined, for example, by observing the cross section of the particles with a TEM (transmission electron microscope). More specifically, a section obtained by embedding the toner particles in a resin and cutting with a microtome is dyed with ruthenium oxide or the like, if necessary, and observed with a TEM. Can be confirmed.

The toner for developing an electrostatic image of the present invention comprises a mixture containing at least a binder resin composed of a polyester resin containing an acidic group such as a carboxyl group, a colorant, a release agent, and an organic solvent. By mixing and emulsifying with an aqueous medium in the presence of a base to form resin particles containing at least a colorant and a release agent in a binder resin, the resin particles are separated from the liquid medium and dried. Depending on the manufacturing method
Manufactured and obtained. Further, in this production method, the form of the release agent contained in the mixture is obtained by mixing the release agent and the dispersant in an organic solvent and mixing and further pulverizing and / or dispersing with a medium. Dispersion.

That is, for example, the toner of the present invention is disclosed in Japanese Patent Application Laid-Open No. Hei 8-21655 and Japanese Patent Application Laid-Open No. 10-31963.
No use of an emulsifier or dispersion stabilizer by neutralizing the acid groups contained with a basic neutralizing agent and converting the binder resin into a self-water-dispersible resin as disclosed in JP-A-9 And granulation using an emulsifier or a dispersion stabilizer as disclosed in Japanese Patent Application Laid-Open No. 1-158042.

A polyester resin containing an acidic group such as a carboxyl group becomes self-water dispersible by neutralizing the acidic group. A resin having self-water dispersibility increases hydrophilicity by making an acidic group anionic, and can be dispersed in an aqueous medium (water or a liquid medium containing water as a main component) without using an emulsifier or a dispersion stabilizer. I do.

The base used to neutralize the acidic group (carboxyl group) is not particularly limited, and is, for example, an inorganic base such as sodium hydroxide, potassium hydroxide or ammonia, or an organic base such as diethylamine, triethylamine or isopropylamine. A base is used.

Examples of the organic solvent for dissolving or dispersing the binder resin, the colorant, and the wax (release agent) include hydrocarbons such as pentane, hexane, heptane, benzene, toluene, xylene, cyclohexane and petroleum ether. Halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, and carbon tetrachloride; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate. Used. These solvents are
They can be used alone or in combination of two or more. The organic solvent is preferably one that dissolves the binder resin, has a relatively low toxicity, and has a low boiling point that is easy to remove the solvent in the subsequent step. As such a solvent, methyl ethyl ketone is most preferred.

Prior to dissolving or dispersing the binder resin, the coloring agent and the wax (release agent) in the organic solvent to form a mixture, the wax (release agent) contained in the mixture is removed. The form is prepared as follows. A release agent and a dispersant are charged in advance to an organic solvent, and the mixture is pulverized and / or dispersed by a medium to obtain a dispersion of the release agent. When the dispersion liquid is prepared in this manner, the dispersion liquid has fine particles of the dispersant adhere to the surface of the release agent by pulverization and / or dispersion by a medium, and these are integrated. Then, a part of the attached dispersant is dissolved in the organic solvent, and due to the steric hindrance effect of the attached dispersant, the release agent is uniformly dispersed without aggregation in the dispersion.

Here, as the dispersant used, the above-mentioned second polyester resin (II) is suitably used. As the polyester resin (II), those which can be used as the polyester resin (I) can be used as they are, and in particular, an acidic group-containing linear polyester resin or a resin containing the same. Preferably, it is The polyester resin (II)
May be different from the polyester resin (I) used as the binder resin, but the same resin may be used, especially in the case of a color toner, since the compatibility with the binder resin is good. It is preferable in terms of management and production management. As the dispersant, an emulsifier, a polymer dispersant, or the like can be used instead of the polyester resin (II).

The dispersant varies depending on the material used, but the weight ratio of the release agent / dispersant is 20%.
It is preferred to be about / 80 to 80/20. If the amount of the dispersant is less than 20% by weight, the above-described effect of preventing the aggregation of the release agent may not be sufficiently obtained. On the other hand, if the amount exceeds 80% by weight, the dispersant adheres to the surface of the release agent. This is because the amount hardly increases, and therefore, the improvement in the above-described aggregation preventing effect of the release agent cannot be expected much.

Examples of the organic solvent for charging the release agent and the dispersant include those mentioned above as the organic solvent for dissolving or dispersing the binder resin, the colorant, and the wax (release agent). , Can be used as is. The amount of the organic solvent is not particularly limited, but the solid content of the release agent and the dispersant is about 10 to 50% by weight. When the amount of the solvent is less than 50% by weight, a uniform dispersion cannot be obtained. On the other hand, when the amount exceeds 90% by weight, the dispersion density of the release agent is reduced. This is because when the liquid is added to the organic solvent, the amount of the solvent becomes excessive and the productivity is reduced. The organic solvent may be different from the organic solvent for dissolving or dispersing the binder resin or the like, but it is preferable to use the same organic solvent in terms of quality control and production control.

As a method using a medium for pulverizing and / or dispersing a release agent and a dispersant, specific examples include an Eiger motor mill, SC mill, ball mill, sand mill, attritor, coball mill, DC mill, and fine mill. And a method using a so-called medium mill or medium stirring mill.

In order to make the release agent particles having the dispersant adhered to be smaller and more uniform particles, when the release agent and the dispersant are pulverized and / or dispersed by a medium, the pulverization and / or dispersal is carried out. The dispersion temperature in the dispersion region is preferably set to 50 ° C or lower, more preferably 30 to 40 ° C. If the temperature of the dispersion exceeds 50 ° C., the release agent that has been made into fine particles is likely to re-agglomerate, and the release agent to which the dispersant has adhered is less likely to become the desired uniform fine particles. In order to adjust to such a temperature, it is necessary to effectively cool the heat generated by the dispersion treatment in the pulverization and / or dispersion region. Therefore, in performing pulverization and / or dispersion, it is preferable to use a device having a mechanism capable of effectively cooling the dispersion liquid, for example, an Eiger motor mill, SC mill, sand mill, attritor, koball mill, DCP mill, fine mill, or the like. preferable.

As the shape of the medium used for producing such a dispersion, a columnar shape or a spherical shape can be adopted. However, considering the efficiency of pulverization and dispersion and adaptation to a dispersing apparatus, a spherical shape is considered. Is preferred. As for the size of the spherical media, the optimum value differs depending on each dispersing device. For example, although it is preferable that the diameter is 1 to 50 mm in a ball mill, the shape of the releasing agent to which the dispersing agent is attached is effectively uniform. In order to obtain a diameter of 1 to 10
mm is preferable.

The dispersion of the release agent thus prepared is mixed with a binder resin and a colorant, and these are charged into an organic solvent and dissolved or dispersed to prepare a mixture. The mixture is then mixed with an aqueous medium and emulsified to form resin particles containing at least a colorant and a release agent in a binder resin (polyester resin (I)).

The method for neutralizing the acidic group of the polyester resin (I) with a base is as follows: (1) preparing a mixture containing a binder resin having a neutralized acidic group, a colorant, a wax and an organic solvent. Or (2) a method of preparing a mixture containing a binder resin having an acidic group, a colorant, a wax and an organic solvent, and then neutralizing the mixture with a base.

The method of emulsifying the polyester resin after neutralizing the acidic group with a base is as follows: (3) a method of emulsifying the mixture by adding the mixture to an aqueous medium; or (4) a method of adding an aqueous medium to the mixture. Method. The above (2)
The combination of (4) and (4) is preferable because the particle size distribution is improved.

In addition, there is a method in which a basic neutralizing agent is mixed in an aqueous medium, but from the viewpoint of particle size distribution, a neutralization and emulsification method using the above combination is preferable. At the time of emulsification, if necessary, as long as the effects of the present invention are not impaired,
An emulsifier and / or a dispersion stabilizer can be used in combination.

As the dispersion stabilizer, inorganic dispersion stabilizers,
Organic dispersion stabilizers can be used, and for example, water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidene, hydroxyethyl cellulose, and carboxymethyl cellulose are used. As the emulsifier, for example, a nonionic surfactant such as polyoxyethylene alkylphenol ether; an anionic surfactant such as sodium alkylbenzenesulfonate; a cationic surfactant is used.

When these dispersion stabilizers or emulsifiers are used, they can be used alone or in combination of two or more. In addition, an emulsifier and a dispersion stabilizer may be used in combination, but it is general to use an emulsifier in combination mainly with the dispersion stabilizer. When a dispersion stabilizer or an emulsifier is used, its concentration in an aqueous medium is preferably in the range of 0.5 to 3.0% by weight.

As a method for producing an organic solvent solution of a kneaded material in which a colorant, a wax, and the like are dispersed in a binder resin, (1) a binder resin is dissolved in an organic solvent, and a colorant and a wax are added thereto;
A method of dispersing using a general mixer / disperser such as Despa (dispersion stirrer), ball mill, bead mill, sand mill, continuous bead mill and the like. Alternatively, (2) a method of separately dispersing a colorant or a wax using the above-described general mixer / disperser and then mixing the resultant with a solution of a binder resin in an organic solvent may be used. According to such a wet dispersion, cutting of a polymer component (including a gel component) can be suppressed, which is preferable.

Apparatuses for mixing and emulsifying and dispersing an organic solvent solution of the above mixture with an aqueous medium include, for example, a homomixer (Tokiki Kika Kogyo Co., Ltd.) and JP-A-9-1141.
No. 35, a stirrer, a slasher (Mitsui Mining Co., Ltd.), a Cavitron (Eurotech Co., Ltd.), a microfluidizer (Mizuho Industry Co., Ltd.), a Menton-Gaulin homogenizer (Gaulin Co., Ltd.), a nanomizer (Nanomizer Co., Ltd.) Company) and an emulsifying and dispersing machine such as a static mixer.
However, for example, using an anchor blade, a turbine blade, a Faudler blade, a full zone blade, a max blend blade, a meniscus blade, or the like, water is stirred while stirring at a low shear rate of 0.2 to 5 m / s. Is preferred. By performing the emulsification and dispersion under such a low share, generation of fine powder can be suppressed, and a more preferable uniform particle size distribution can be realized. In addition, the low molecular weight component of the polyester resin is not concentrated on the fine powder, so that the balance of the molecular weight distribution in portions other than the fine powder is not lost, and the low-temperature fixability of the toner is not deteriorated.

It is preferable to first remove the organic solvent from the dispersion liquid of spherical to substantially spherical colored resin particles obtained by emulsification by means such as distillation. Next, the aqueous dispersion is subjected to solid-liquid separation by means such as filtration, and the particles are dried to obtain toner particles. It is preferable that the colored resin particles obtained using the emulsifier and the dispersion stabilizer are more thoroughly washed.

The dispersion liquid of spherical to substantially spherical colored resin particles obtained by such emulsification may be prepared, for example, by removing hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, or the like after removing the organic solvent.
With an acid such as oxalic acid, a reverse neutralization treatment is performed to return the neutralized acidic groups and hydrophilic groups on the particle surface to the original functional groups, thereby further reducing the hydrophilicity of the particles themselves, and then removing water. It is preferable to filter and dry.

As the drying method, any of the well-known and commonly used methods can be adopted. For example, a method of drying under normal pressure or reduced pressure at a temperature at which the toner particles do not fuse or agglomerate, a method of freeze-drying, And the like. Further, a method of simultaneously separating and drying the toner particles from the aqueous medium by using a spray drier or the like may also be used. In particular, a method of agitating and drying the powder under reduced pressure while heating at a temperature at which the toner particles do not thermally fuse or agglomerate, or a flash jet drier that instantaneously dries using a heated drying air flow (Seishin Enterprise) Is more efficient and preferable.

When classification for removing coarse particles and fine particles is necessary to adjust the particle size distribution of the formed toner particles, a general air-flow type commercially available for toner or the like is used after drying. It can be performed by a known and commonly used method using a classifier. Further, at the stage when the toner particles are dispersed in the solvent, a method of classifying a water slurry of the toner particles using a centrifugal separator by utilizing a difference in sedimentation depending on the particle diameter may be used. The removal of the coarse particles can be performed by filtering the water slurry of the toner particles with a filter, a wet vibration sieve, or the like. Regarding the particle size distribution of the toner of the present invention, a good image can be obtained with a 50% volume particle size / 50% number particle size of 1.35 or less, more preferably 1.25 or less, as measured by a Coulter Multisizer. Easy and preferred.

The toner for developing an electrostatic image of the present invention obtained as described above has the following formula: average circularity = (perimeter of a circle having the same area as the projected area of particles) /
The average circularity defined by (perimeter of particle projected image) is preferably 0.97 or more, and more preferably 0.98 or more. By having such a spherical shape to a substantially spherical shape, the toner for developing an electrostatic image of the present invention can ensure good powder fluidity even if the particle diameter is reduced, and ensure good transfer efficiency. This can provide excellent image quality. The average circularity is determined by the SEM of the toner particles.
(Scanning electron microscope) It can also be obtained by taking a photograph, measuring and calculating it, but it can be easily obtained by using a flow particle image analyzer FPIP-1000 manufactured by Toa Medical Electronics Co., Ltd. In the present invention, measurement was performed using this device.

The toner for developing an electrostatic charge image preferably has a volume average particle diameter in the range of 1 to 13 μm from the viewpoint of image quality to be obtained.
A thickness of about 10 μm is more preferable because it is easy to obtain matching with a current machine. For a color toner, the volume average particle size is preferably about 3 to 8 μm. When the volume average particle diameter is small, not only the resolution and the gradation are improved, but also the effect that the thickness of the toner layer for forming the print image is reduced and the toner consumption per page is reduced is preferable.

The dried powder toner particles can be used as a developer as they are, but external additives such as inorganic oxide fine particles and organic polymer fine particles, which are well-known and used as toner external additives, are added to the surface of the toner particles. It is preferable to improve the properties such as fluidity and chargeability by adding the compound. Examples of such external additives include silica, titanium oxide, aluminum oxide,
And vinyl (co) polymers. When these external additives are used, the amount of addition is 0.0
A range of 5 to 5% by weight is preferred.

The electrostatic image developing toner of the present invention can be used as a one-component developer or a two-component developer mixed with a carrier for developing an electrostatic latent image by electrophotography. The type of carrier is not particularly limited, and known and commonly used iron powders, ferrites, magnetites, and the like and carriers coated with a resin therefrom are used.

Further, the toner for developing an electrostatic image of the present invention comprises:
Holes on a flexible printed circuit board having electrodes around the electrodes that function to adjust the amount of toner passing through, for example, by frictionally charging powdered toner using a non-magnetic one-component developing device having a developer carrying roll and a layer regulating member. Can be suitably used for a so-called toner-jet printer, which is a method of forming an image by directly spraying the paper on the back electrode. The toner of the present invention is excellent in fixability and color characteristics, and is spherical, so that the control of the toner flight in the toner jet method becomes easier as compared with the irregular toner.

[0066]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In addition,
In Examples and Comparative Examples, parts are parts by weight and water is deionized water unless otherwise specified.

(Synthesis example of polyester resin) Trimellitic anhydride (TMA) as polycarboxylic acid, terephthalic acid (TPA), isophthalic acid (IP) as dicarboxylic acid
A), polyoxypropylene (2,4) -2,2-bis (4-hydroxyphenyl) as an aromatic diol
Propane (BPA-PO), polyoxyethylene (2,
4) Using 2,2-bis (4-hydroxyphenyl) propane (BPA-EO) and ethylene glycol (EG) as an aliphatic diol at the respective molar composition ratios shown in Table 1,
As a polymerization catalyst, tetrabutyl titanate was charged into a separable fresco at 0.3% by weight based on the total amount of monomers, and a thermometer, a stir bar, a condenser, and a nitrogen inlet tube were attached to the upper part of the flask, and an atmospheric pressure nitrogen gas was supplied in an electric heating mantle heater. After reacting at 220 ° C. for 15 hours under an air stream, the pressure was sequentially reduced, and the reaction was continued at 10 mmHg. The reaction is ASTM
-Pursuit was performed by the softening point according to E28-517, and when the softening point reached a predetermined temperature, the vacuum was stopped to terminate the reaction. Tables 1 and 2 show the composition and physical property values (characteristic values) of the synthesized resin. In addition, the gel component in Tables 1 and 2 indicates a tetrahydrofuran (THF) -insoluble component. Table 1 shows linear polyester resins, and Table 2 shows crosslinked polyester resins.

[0068]

[Table 1]

[0069]

[Table 2]

In Tables 1 and 2, "T1 / 2 temperature" means the flow tester CFT-500 manufactured by Shimadzu Corporation as described above.
Is a value measured using a nozzle diameter of 1.0 mmΦ × 1.0 mm, a load of 10 kg per unit area (cm ² ), and a heating rate of 6 ° C. per minute. The glass transition temperature “Tg” is a differential scanning calorimeter DSC-50 manufactured by Shimadzu Corporation.
Is a value measured at a heating rate of 10 ° C. per minute by the second run method.

(Example of Preparation of Release Agent and Release Agent Dispersion) 105 parts of the release agent, 45 parts of the polyester resin (II) (R1 in Table 1) serving as a dispersant in the present invention, and 280 parts of methyl ethyl ketone were used. The mixture was charged into a ball mill, stirred for 18 hours, and then taken out. The solid content was adjusted to 20% by weight to obtain a fine dispersion (W1 to W6) of a release agent. For comparison, a polyester resin (I
Without adding I), 150 parts of a release agent was charged into a ball mill, and fine dispersions (W7, W8) were obtained in the same manner as the fine dispersions (W1 to W6). Table 3 shows properties and the like of the obtained release agent dispersion.

[0072]

[Table 3]

The release agents shown in Table 3 are as follows. PP: "VISCOL 660P" (polypropylene wax manufactured by Sanyo Kasei) PE: "LICOWAX PE-130PDR" (polyethylene wax manufactured by Clariant) FT-100: "LUVAX-1211" (Fisher Tropsch wax manufactured by Nippon Seiro) Ester: "WEP-" 5 "(Synthetic ester wax made by NOF Corporation)

(Preparation Example of Colorant Dispersion) Methyl ethyl ketone was charged into a ball mill so that the content of the colorant, the resin and the solid content was 35 to 50%, stirred for 18 to 36 hours, and then taken out. The content was adjusted to 20% by weight to obtain colorant dispersions (P1, P2). Table 4 shows the properties of the obtained colorant dispersion.

[0075]

[Table 4]

The coloring agents shown in Table 4 are as follows. Carbon: ELFTEX-8 (manufactured by Cabot) Cyan: Fast Gen Blue TGR (manufactured by Dainippon Ink and Chemicals, Inc.)

(Preparation of mill base)
The resin and methyl ethyl ketone (MEK) were mixed with a disper, the solid content was adjusted to 55%, and the mill base (MB
1 to MB7). Table 5 shows the composition of the prepared mill base.

[0078]

[Table 5]

Example 1 MB2 shown in Table 5 was
5.5 parts, 115 parts of W4 shown in Table 3, 57.5 parts of methyl ethyl ketone, and 29.5 parts of isopropyl alcohol.
0 parts and 15.8 parts of 1N aqueous ammonia solution were charged into a cylindrical container and stirred well. Subsequently, 230 parts of water was added, the liquid temperature was adjusted to 30 ° C., and 44 parts of water was added dropwise with stirring.
Phase inversion emulsification was performed. After stirring for 30 minutes, the rotation was reduced and 400 parts of water were added. Here, when the water slurry of the particles was observed with an optical microscope, no aggregate of the release agent was observed, and no release agent flowing out was observed. When the particle size distribution was measured with a Coulter counter, Dv / Dn was 1.32, and no generation of coarse particles was observed.

Next, the solvent was removed by distillation under reduced pressure, and the residue was washed with filtered water. Subsequently, the obtained wet cake was re-dispersed in water, a 1N hydrochloric acid aqueous solution was added until the pH of the dispersion became about 4, and the filtration and water washing were repeated. The wet cake thus obtained was freeze-dried and then classified using an airflow classifier to obtain toner particles having a volume average particle size of 7.4 μm and an average circularity of 0.981.

The obtained toner particles were embedded in a resin, cut with a microtome, and the cross section stained with ruthenate tetroxide was observed with a TEM (transmission electron microscope). It was observed that it was encapsulated and dispersed almost uniformly in the particles. afterwards,
Using a Henschel mixer, the resulting toner particles 10
To 0 part, 1.5 parts of hydrophobic silica and 0.5 part of titanium oxide were externally added to obtain a powder toner (toner for developing an electrostatic image).

(Example 2) MB2 shown in Table 5
5.5 parts, 115 parts of W4 shown in Table 3, 57.5 parts of methyl ethyl ketone, 28.
06.5 parts and 26.5 parts of a 1N aqueous ammonia solution were charged into a cylindrical container and stirred well. Subsequently, 230 parts of water was added, the liquid temperature was adjusted to 30 ° C., and 44 parts of water was added dropwise with stirring.
Phase inversion emulsification was performed. After stirring for 30 minutes, the rotation was reduced and 400 parts of water were added. Here, when the water slurry of the particles was observed with an optical microscope, no aggregate of the release agent was observed, and no release agent flowing out was observed. When the particle size distribution was measured with a Coulter counter, Dv / Dn was 1.35, and no generation of coarse particles was observed.

Next, the solvent was removed by distillation under reduced pressure, and the residue was washed with filtered water. Subsequently, the obtained wet cake was re-dispersed in water, a 1N hydrochloric acid aqueous solution was added until the pH of the dispersion became about 4, and the filtration and water washing were repeated. The wet cake thus obtained was freeze-dried, and then classified using an airflow classifier to obtain toner particles having a volume average particle size of 5.2 μm and an average circularity of 0.984.

The obtained toner particles were embedded in a resin, cut with a microtome, and a cross section stained with ruthenate tetroxide was observed with a TEM (transmission electron microscope). It was observed that it was encapsulated and dispersed almost uniformly in the particles. afterwards,
Using a Henschel mixer, the resulting toner particles 10
0 parts are externally added with 2 parts of hydrophobic silica and 1 part of titanium oxide,
A powder toner (toner for developing an electrostatic image) was obtained.

(Comparative Example 1) MB2 shown in Table 5
5.5 parts, 80.5 parts of W7 shown in Table 3, 57.5 parts of methyl ethyl ketone, 2 parts of isopropyl alcohol
9.0 parts, 25.8 parts of a 1N aqueous ammonia solution was charged into a cylindrical container and stirred well. Subsequently, 230 parts of water was added, the liquid temperature was adjusted to 30 ° C., and 44 parts of water was added dropwise with stirring to perform phase inversion emulsification. After stirring for 30 minutes, the rotation was reduced and 400 parts of water were added. Here, when the water slurry of the particles was observed with an optical microscope, many aggregates of the release agent were observed, and when the particle size distribution was measured with a Coulter counter, Dv / Dn was 1.54,
Generation of fine particles and coarse particles was observed.

Next, the solvent was removed by distillation under reduced pressure, and the residue was washed with filtered water. Subsequently, the obtained wet cake was re-dispersed in water, a 1N hydrochloric acid aqueous solution was added until the pH of the dispersion became about 4, and the filtration and water washing were repeated. The wet cake thus obtained was freeze-dried and then classified using an airflow classifier to obtain toner particles having a volume average particle size of 7.4 μm and an average circularity of 0.981. The obtained toner particles were embedded in a resin, cut with a microtome, and the cross section stained with ruthenate tetroxide was observed with a TEM (transmission electron microscope). As a result, the pigment and wax were encapsulated in the binder resin. However, the amount of the release agent included in each particle was not uniform, and it was observed that the coarse particles contained a large amount of the release agent. Thereafter, using a Henschel mixer, 1.5 parts of hydrophobic silica and 0.5 parts of titanium oxide were externally added to 100 parts of the obtained toner particles to obtain a powder toner (toner for developing an electrostatic image). .

(Other Examples and Comparative Examples) The other Examples and Comparative Examples are basically manufactured by the same method as in Example 1, and the amounts of the solvent and the base to be added are appropriately adjusted. As a result, each powder toner was obtained. Table 6 shows the used MB (mill base) and the used release agent, the measured values such as the average circularity, the presence or absence of coarse particles, the glass transition temperature Tg, and the fixing temperature width of the powder toners of the respective Examples and Comparative Examples. Show.

[0088]

[Table 6]

The glass transition temperature, Tg, was increased by 10 ° C./min by the second run method using a differential scanning calorimeter DSC-50 manufactured by Shimadzu Corporation in the same manner as in Tables 1 and 2 above. Measured at speed. The fixing temperature range was determined by a fixing property test described below, and was indicated by a range between an upper limit value and a lower limit value. (Fixing property test) For each of the powder toners of Examples and Comparative Examples, a silicon-coated ferrite carrier (particle size:
μm) and the toner concentration was 3% by weight, and the printing paper imaged with a two-component developing type copying machine was 9% each.
The sheet was passed through a heat roll (oil-less type) of Ricoh Imagio DA-250 at a speed of 0 mm / sec to perform fixing.
Cellotape (registered trademark) is attached to the image after fixing, and the ID (image density) after peeling is 90% or more of the original ID,
The surface temperature of the heat roll when no offset was observed was defined as “fixing temperature”.

From the results shown in Table 6, it was confirmed that the fixing examples of the present invention had good fixing start temperature and hot offset resistance, and had a wide fixing temperature range.

(Image Generation Test) Further, with respect to the powder toners of the respective examples, image generation was performed using a commercially available non-magnetic one-component developing type printer. Further, the powder toner of each example was mixed with a silicon-coated ferrite carrier (particle diameter: 80 μm) so that the toner concentration became 3% by weight, and an image output test was performed using a two-component developing type copying machine. In each case, good images were obtained.

[0092]

As described above, the toner for developing an electrostatic image according to the present invention is characterized in that the form of the release agent contained in the mixture is determined by mixing the release agent and the dispersant in an organic solvent. It is a dispersion of the release agent obtained by further pulverized and / or dispersed by a medium,
The dispersion of the release agent in the dispersion is promoted by the presence of the dispersant, and reaggregation is prevented, so that even when the dispersion is added to the mixture, the release agent does not aggregate and is easily formed. , Whereby the release agent is uniformly dispersed in the particles to be formed. Therefore, the toner for developing an electrostatic image obtained in this manner is one in which the generation of coarse particles is prevented, and thereby has a good fixing start temperature and a good hot offset resistance. In addition, by making the particles spherical and small in particle size, powder fluidity, transfer efficiency, resolution, and gradation are excellent, and therefore, a developed image of excellent quality can be provided. .

[Brief description of the drawings]

FIG. 1 is a diagram for explaining how to obtain a flow tester value, wherein FIG. 1 (a) is a side sectional view showing an outline of a measuring device,
(B) is a graph for explaining a method of obtaining each flow tester value from a measured value.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H005 AA01 AA06 AA15 AA21 AB03 CA08 CA13 CA14 EA03 EA07

Claims (6)

[Claims] A mixture comprising an acidic group-containing polyester resin (I) as a binder resin and at least a binder resin, a colorant, a release agent and an organic solvent is mixed with an aqueous medium in the presence of a base. By mixing and emulsifying, in a toner for developing an electrostatic image obtained by a production method of forming resin particles containing at least a colorant and a release agent in the binder resin, the toner is contained in the mixture. The form of the release agent is a dispersion of the release agent obtained by mixing and releasing the release agent and the dispersant in an organic solvent and further pulverizing and / or dispersing the mixture with a medium. Charge image developing toner. 2. A release agent selected from the group consisting of hydrocarbon waxes such as polypropylene wax, polyethylene wax and Fischer-Tropsch wax, and synthetic ester waxes. 2. The toner for developing an electrostatic image according to 1. 3. The polyester resin (I) having an acidic group,
(A) Constant load extrusion type capillary tube rheometer T1 /
2 A linear polyester resin having a temperature of 80 ° C. or more and 120 ° C. or less and a glass transition temperature Tg of 40 ° C. or more and 75 ° C. or less, and (B) a T1 / 2 temperature measured by a constant load extrusion type capillary rheometer. It is a mixture of a crosslinked polyester resin having a glass transition temperature Tg of not less than 40 ° C. and not more than 75 ° C. which is higher than 120 ° C. and not higher than 210 ° C. A) / (B) = 20/80 to 80/20, and when T1 / 2 temperature is T1 / 2 (A) and T1 / 2 (B), respectively, 20 ° C. <T1 / 2 (B) − 3. The toner for developing an electrostatic image according to claim 1, wherein T1 / 2 (A) ≦ 120 ° C. 4. The toner according to claim 1, wherein the dispersant is a polyester resin (II). 5. The toner for developing an electrostatic image according to claim 4, wherein the polyester resin (II) is a linear polyester resin containing an acidic group. 6. Average circularity = (perimeter of a circle having the same area as the projected area of a particle) /
6. The electrostatic image developing toner according to claim 1, wherein an average circularity defined by (perimeter of particle projected image) is 0.97 or more.