JP2003255606A - Method for manufacturing white toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a white toner having high hiding property in which a fused and kneaded material of a binder resin and a colorant containing a white pigment is pulverized to obtain the white toner having the advantages that the white pigment is prevented from exposing on the toner surface and the toner has a stable charge amount and sharp distribution of the charges even when the toner is made small in size or the white pigment is used in a large amount. <P>SOLUTION: The method for manufacturing the toner includes processes of kneading a mixture of a colorant and a binder resin (1) in a fused state, then cooling the mixture and pulverizing. As for the colorant, the following white resin particles are used. The white particles are manufactured by dispersing the white pigment in a binder resin (2) to prepare a white pigment dispersion material, emulsifying the white pigment dispersion material in a water-based medium and then separating the particles from the water-based medium. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in electrophotographic copying machines, printers, fax machines, etc., and is also used in toner jet type printers, etc., for producing a white toner for developing an electrostatic image. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, the following pulverization method has been used as a method for producing a toner used in electrophotography. That is, a binder resin and a colorant, and if necessary, additives such as a charge control agent were added, and they were mixed by a Henschel mixer or the like, and then the obtained mixture was melt-kneaded by a twin-screw extruder or the like. After that, the toner is pulverized and classified to obtain a toner having a predetermined particle diameter.

The toner manufactured by such a manufacturing method is used as a toner of a one-component developing system or a two-component developing system. In any system, the triboelectrification characteristic of the toner has a great influence on the developing characteristic of the toner. Influence. For example, when the toner particles have an insufficient electric charge, the toner particles have a small electrostatic attraction with the carrier and thus contaminate the periphery of the developing device. Alternatively, it scatters on a portion other than the electrostatic charge image on the photoconductor to cause fogging on the printed matter after development. Further, when the toner particles have an excessively large electric charge, the amount of the toner particles attached to the photoconductor or the amount of the toner particles transferred to the transfer material decreases, and the image density of the printed matter decreases. Furthermore,
When the charge amount of each toner particle is non-uniform and the distribution of the charge amount of the toner particle is wide, various undesirable problems occur in addition to the fluctuation of the image density.

By the way, in recent years, as colorization of electrophotographic printers and higher resolution of printed images have progressed, white characters or white images are printed by using white toner on chromatic color paper, and color images are used. The use of printing a solid white image in the background has been widespread in order to improve the color developability of. Further, for a colored print image formed with chromatic toner, a white toner image is printed so as to cover a part of the colored toner image according to the gradation to be expressed, or a colored toner image is formed with the white toner. Applications have also been developed for completely hiding and erasing.

Generally, a white toner is obtained by dispersing a white pigment such as titanium oxide in a binder resin. In order to use this white toner for the above-mentioned application, the white toner used has a strong hiding power for hiding the color of the chromatic color paper as the base or the printed image formed by the chromatic color toner. Will be needed. Therefore, conventionally, in order to give a strong hiding power to the white toner, the amount of the white pigment mixed in the binder resin is increased, and the light entering the toner layer forming the printed image is reflected or diffused by the white pigment particles. Was increasing the rate. However, if the amount of white pigment particles is increased to increase the hiding power, the proportion of white pigment particles exposed on the surface of the toner particles will increase. In particular,
In a white toner containing an inorganic pigment such as titanium oxide,
Since the resistance of the inorganic pigment is relatively small, if it is exposed on the toner surface, a sufficient amount of charge cannot be obtained, causing fog, and the problem that the toner remaining on the photoreceptor damages the photoreceptor. Was there. Such a phenomenon is remarkable when the manufacturing method using the above-mentioned pulverization method is used. In particular, in recent years, high-definition images have been demanded, and the particle size of toner particles has been reduced. As the particle size of toner particles decreases, the specific surface area increases, and the colorant becomes the surface of the toner particles. There is a problem that the proportion of people who are exposed to is increasing.

Under the above circumstances, various techniques for minimizing the exposure of the white pigment to the toner surface have been studied. For example, JP-A-5-3415
Japanese Patent Laid-Open No. 62-62 discloses a technique of producing a master containing a white pigment in a high concentration in a binder resin and then dispersing the master in the binder resin having a low miscibility with the binder resin. . However, the technique disclosed in this publication is still insufficient in terms of suppressing the exposure of the white pigment to the toner surface as much as possible, and it is possible to improve the charging characteristics of the white toner to such an extent that it can be sufficiently satisfied in practical use. It has not been realized.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. An object of the present invention is to pulverize a melt-kneaded product of a binder resin and a colorant containing a white pigment to obtain a toner. In the pulverization method to be produced, the white pigment is not exposed on the toner surface, and even if the toner has a small particle size or a large amount of the white pigment is used, a stable charge amount and a sharp charge amount distribution are obtained. The present invention provides a method for producing a white toner having high hiding power.

[0008]

Means for Solving the Problems As a means for solving the above problems in the pulverization method, the present inventors have developed a colorant for white resin particles obtained by emulsifying a mixed dispersion of a resin and a white pigment in an aqueous medium. It was found that the above-mentioned problems can be solved by using the above, and the present invention has been completed.

That is, the present invention is a method for producing a toner by the steps of kneading a mixture containing a colorant and a binder resin (1) in a molten state, cooling the mixture, and then pulverizing the mixture. A white pigment dispersion, in which a white pigment is dispersed in the binder resin (2) as the colorant, and then the white pigment dispersion is emulsified in an aqueous medium and further separated from the aqueous medium. The present invention provides a method for producing a white toner, which comprises using white resin particles produced by the above method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Binder resin used in the present invention (1)
Any of those generally used as a binder resin in toner can be used without particular limitation. Examples thereof include polystyrene, styrene- (meth) acrylic acid ester copolymers, olefin resins, polyester resins, amide resins, polycarbonate resins, epoxy resins, and graft polymers thereof and mixtures thereof. it can.

Among them, polyester resin, styrene- (meta), (meth), etc. are taken into consideration in consideration of charging stability, storage stability, fixing characteristics, and color reproducibility when used as a resin for color toner containing chromatic organic pigments. ) Acrylic ester copolymer resins can be preferably used.

The polyester resin used as the binder resin (1) in the present invention can be obtained, for example, by dehydration condensation of a dicarboxylic acid and a diol by a usual method. Examples of the dicarboxylic acid include phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, adipic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride,
Examples thereof include dicarboxylic acids such as cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, azelaic acid and sebacic acid, or derivatives thereof.

As the diol, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, pentanediol, hexanediol, bisphenol A, polyoxyethylene-
(2.0) -2,2-bis (4-hydroxyphenyl)
Propane and its derivatives, polyoxypropylene-
(2.0) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene- (2.2) -polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene-
(6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.4)- 2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (3.
3) -2,2-bis (4-hydroxyphenyl) propane and its derivatives, and the like.

Further, for example, polyethylene glycol,
It is also possible to use diols such as polypropylene glycol, ethylene oxide-propylene oxide random copolymer diol, ethylene oxide-propylene oxide block copolymer diol, ethylene oxide-tetrahydrofuran copolymer diol, and polycaprocactone diol.

If necessary, a trifunctional or more aromatic carboxylic acid such as trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride or a derivative thereof, or sorbitol, 1, 2, 3 is used. , 6-hexanetetraol, 1,4-sorbitan, pentaerythritol, 1,2,4-butanetriol, 1,2,
Trifunctional or higher alcohols such as 5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trimethylolbenzene. Or bisphenol A type epoxy resin, bisphenol F type epoxy resin, ethylene glycol diglycidyl ether, hydroquinone diglycidyl ether, N, N-diglycidyl aniline, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolethane Triglycidyl ether, pentaerythritol tetraglycidyl ether, cresol novolac type epoxy resin, phenol novolac type epoxy resin, epoxy group-containing vinylation Use of a polyfunctional epoxy compound having three or more functional groups such as a polymer or a copolymer of the product, an epoxidized resorcinol-acetone condensate, a partially epoxidized polybutadiene, and one or more of semi-dry or dry fatty acid ester epoxy compounds. You can also

The polyester resin used in the present invention can be obtained by carrying out a dehydration condensation reaction or a transesterification reaction using the above raw material components in the presence of a catalyst.
The reaction temperature and reaction time at this time are not particularly limited, but are usually 150 to 300 ° C. and 2 to 24 hours. As the catalyst for carrying out the above reaction, for example, zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate or the like can be appropriately used.

The styrene monomer used in the copolymer resin of styrene- (meth) acrylic acid ester preferably used as the binder resin (1) in the present invention is, for example, styrene, α-methylstyrene or vinyl. There are toluene, p-sulfone styrene, dimethylaminomethyl styrene and the like.

Examples of the (meth) acrylic acid ester monomer include methyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, tertiary butyl (meth) acrylate, octyl (meth) acrylate, 2- Alkyl (meth) acrylates such as ethylhexyl (meth) acrylate and stearyl (meth) acrylate; Alicyclic (meth) acrylates such as cyclohexyl (meth) acrylate; Aromatic (meth) acrylates such as benzyl (meth) acrylate; Hydroxyethyl Hydroxyl group-containing (meth) acrylate such as (meth) acrylate; (meth)
Phosphoric acid group-containing (meth) acrylate such as acryloxyethyl phosphate; Halogen atom-containing (meth) acrylate such as 2-chloroethyl (meth) acrylate and 2,3-dibromopropyl (meth) acrylate; Glycidyl (meth) acrylate Epoxy group-containing (meth) acrylate; Ether group-containing (meth) acrylate such as 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate; Basic nitrogen atom or amide such as dimethylaminoethyl (meth) acrylate Group-containing (meth) acrylate; and the like.

Further, an unsaturated compound copolymerizable therewith can be used if necessary. For example, carboxyl group-containing vinyl monomers such as (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; sulfo group-containing vinyl monomers such as sulfoethylacrylamide; nitrile group-containing vinyl monomers such as (meth) acrylonitrile; Ketone group-containing vinyl monomers such as vinyl methyl ketone and vinyl isopropenyl ketone; N-vinyl imidazole, 1-vinyl pyrrole, 2
-Vinylquinoline, 4-vinylpyridine, N-vinyl 2
-Vinyl monomers containing a basic nitrogen atom or an amide group such as -pyrrolidone and N-vinylpiperidone can be used.

The crosslinking agent may be used in the range of 0.1 to 2% by weight based on the vinyl monomer. As the crosslinking agent, for example, divinylbenzene, divinyl ether, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,3-
Butylene glycol di (meth) acrylate, 1,6-
Hexane glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and the like can be mentioned.

Alternatively, in the resin using a styrene- (meth) acrylic acid ester copolymer obtained by copolymerizing the above-mentioned carboxyl group-containing vinyl monomer, a metal salt may be used to form a crosslinked resin. A as a metal salt
l, Ba, Ca, Cd, Co, Cr, Cu, Fe, H
Examples thereof include halides, hydroxides, oxides, carbonates, carboxylates, alkoxylates, chelate compounds and the like of g, Mg, Mn, Ni, Pb, Sn, Sr, Zn and the like. The crosslinking reaction can be carried out by heating and stirring in the presence of a solvent.

As a method for producing a styrene- (meth) acrylic acid ester copolymer, an ordinary polymerization method can be adopted. The polymerization reaction is carried out in the presence of a polymerization catalyst such as solution polymerization, suspension polymerization or bulk polymerization. The method of doing is mentioned. Examples of the polymerization catalyst include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-
Carbonitrile), benzoyl peroxide, dibutyl peroxide, butyl peroxybenzoate and the like, and the amount thereof is 0.1 to 0.1% of the vinyl monomer component.
10.0% by weight is preferred.

The binder resin (1) used in the present invention has only to have a glass transition point and a melt viscosity characteristic suitable as a toner, and a softening point of 90 ° C. or higher, especially 90 ° C. or higher. It is preferably in the range of 180 ° C, more preferably in the range of 95 ° C to 160 ° C. Softening point is 9
When the temperature is lower than 0 ° C., the toner is apt to cause an agglomeration phenomenon, which causes troubles during storage and printing, and when the temperature is higher than 180 ° C., the fixability is often deteriorated. Further, the glass transition temperature (Tg) is preferably 40 ° C. or higher, and among them, the one having Tg of 45 to 85 ° C. is particularly preferable. The acid value is preferably 30 or less, and particularly preferably 10 or less. If the acid value is too high, the charge amount is lowered and the desired charge amount cannot be obtained.

The softening point of the resin in the present invention is defined as the T1 / 2 temperature measured by using a constant load extrusion type capillary rheometer, a flow tester CFT-500 manufactured by Shimadzu Corporation. Measurement conditions with a flow tester are: piston cross-sectional area 1 cm ² , cylinder pressure 0.98 MPa, die length 1 m.
m, die hole diameter 1 mm, measurement starting temperature 50 ° C., temperature rising rate 6 ° C./min, sample weight 1.5 g.

The white resin particles used as a colorant in the production method of the present invention are prepared by dispersing a white pigment in the binder resin (2) to produce a white pigment dispersion, and then the white pigment dispersion is treated with an aqueous medium. It is produced through a process of emulsifying in and further separating from an aqueous medium. The white resin particles produced in this manner are characterized in that the pigment is adsorbed by the resin, the white pigment is encapsulated in each particle, and the white pigment is not exposed on the surface of the white resin particles. .
This is because after dispersing the white pigment in the binder resin (2), the white resin particles are produced in the water system while utilizing the hydrophilic-hydrophobic balance of the resin. Therefore, in the toner of the present invention produced by the pulverization method using the white resin particles having such characteristics as a colorant, the exposure of the white pigment on the surface of the toner particles can be reduced as much as possible. In particular, when the white pigment dispersion is emulsified in an aqueous medium to form white resin particles and then a crosslinked structure is introduced into the binder resin (2), the effect becomes remarkable. The binder resin (2) in the present invention is a binder resin for dispersing a white pigment to form white resin particles. In the binder resin (1) in which the white resin particles are dispersed, the binder resin (2) is used. Distinguish.

As the binder resin (2) for forming the white resin particles, at least one resin selected from styrene (meth) acrylic resin, urethane resin, urethane urea resin, or polyester resin is used. It is preferable. The binder resin (2) can be selected with the same effect of the present invention regardless of which resin is used. However, in the application where color development such as full color and transparency are required, the binder resin (2) is selected. It is preferable to select a resin having good compatibility with the binder resin (1) in which the used white resin particles are dispersed. Therefore, it is particularly preferable that the binder resin (2) and the binder resin (1) are the same type of resin. When a crosslinked structure is introduced into the binder resin (2), styrene (meth) is used.
Acrylic resins are preferred.

The particle size of the white resin particles is 0.05 μm to 5 μm.
μm, and more preferably in the range of 0.1 μm to 3 μm. If the particle size is smaller than 0.05 μm, the aggregating property becomes high and the dispersion in the binder resin (1) may become uneven, which is not preferable. On the other hand, when the particle size is larger than 5 μm, the dispersion of the particles in the binder resin (1) is not uniform, and it affects the toner and the hue and transparency, which is not preferable. The particle size of the white resin particles is a value measured using LS230 type (particle size distribution measuring device by laser diffraction / scattering method) manufactured by Beckman Coulter, Inc.

The ratio of the binder resin (2) to the white pigment is as follows: binder resin (2) / white pigment = 90/10 to 10/9
0 (weight ratio) is preferable, and 80/20 to 20
It is more preferably / 80.

Next, the method for producing the white resin particles of the present invention will be described. The method for producing white resin particles of the present invention comprises the following steps. First step: a step of producing a white pigment dispersion by dispersing a white pigment in a binder resin (2), Second step: emulsifying the white pigment dispersion obtained in the first step in an aqueous medium And a step of producing white resin particles, and a third step: a step of separating the obtained white resin particles from an aqueous medium and drying.

The first step is a step of producing a white pigment dispersion in which the pigment is finely dispersed, using a known and commonly used means.
As a method for finely dispersing the white pigment in the resin, there are a dry melt-kneading method and a wet media dispersion method. The melt-kneading method is not particularly limited, but for example, a mixture containing the pigment and the binder resin (2) is bound using a pressure kneader, a heating twin roll, a twin-screw extrusion kneader, or the like. This is a method in which the resin (2) is heated to a temperature not lower than the softening point and not higher than the thermal decomposition temperature and melt-kneaded.

The media dispersion method is, for example, a method in which the binder resin (2) and the pigment are mixed with an organic solvent, and this is kneaded and dispersed using a ball mill or the like. More specifically, the binder resin (2) is dissolved in an organic solvent, the pigment is added thereto, and a mixer / disperser using a general media such as a ball mill, a bead mill, a sand mill, and a continuous bead mill is used. To a masterbatch by dispersing the pigment, and further mixing the binder resin (2) for dilution and an additional organic solvent, and using a stirrer such as Despar, a resin solution in which the pigment is finely dispersed in the organic solvent (white pigment There is a method for producing a dispersion).

In the above-mentioned wet method, as the organic solvent for dissolving or dispersing the binder resin (2) and the pigment, for example, pentane, hexane, heptane, benzene,
Hydrocarbons such as toluene, xylene, cyclohexane, petroleum ether; halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, carbon tetrachloride; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; Esters such as ethyl acetate and butyl acetate, and ethers such as tetrahydrofuran and diethyl ether are used. These solvents may be used as a mixture of two or more kinds, but from the viewpoint of solvent recovery, it is preferable to use the same kind of solvent alone. The organic solvent is preferably one that dissolves the binder resin (2), has relatively low toxicity, and has a low boiling point that is easy to remove the solvent in a later step. As such a solvent, methyl ethyl ketone is most preferable. preferable.

The second step is a step of producing white resin particles by emulsifying the white pigment dispersion obtained in the first step in an aqueous medium. There are two methods for emulsifying a white pigment dispersion in an aqueous medium: a method using an emulsifier or a dispersion stabilizer and a method using self-emulsification of a resin.
The method is a method of emulsifying a white pigment dispersion in water under high shear in the presence of an emulsifier or a dispersion stabilizer. The method (2) is a method of using an acidic group-containing resin as the binder resin (2) and emulsifying it in an aqueous medium in the presence of a basic neutralizing agent. The binder resin (2) is preferably one that can be stably present in an aqueous medium by emulsifying in an aqueous medium without using an emulsifier or a dispersion stabilizer by neutralizing an acidic group. By using a resin having such characteristics, the charging characteristics of the toner are not adversely affected, and
Since the hydrophilicity of the resin itself is improved, coarse particles are less likely to occur, and white resin particles having a uniform particle size distribution can be easily produced, which is preferable. Furthermore, according to the manufacturing method of
The pigment can be contained in the white resin particles at a high concentration, or the pigment can be sufficiently encapsulated so as not to be exposed on the surface of the white resin particles. There is also an advantage that the particle size of the white resin particles can be easily adjusted by appropriately setting the neutralization ratio of the acidic groups.

Further, in the production method (1), there is a method using an organic solvent, which is preferable as a method for producing the colored resin particles used in the present invention. Specifically, a white pigment dispersion is produced by dissolving or dispersing the binder resin (2) and the pigment in an organic solvent by the above-mentioned media dispersion method, and then in the presence of a basic neutralizing agent. Is a method for producing a suspension of white resin particles by emulsifying the white pigment dispersion by mixing with an aqueous medium and further removing the organic solvent under reduced pressure.

The binder resin (2) used in this method is a resin having an acidic group such as a carboxyl group. The binder resin (2) containing an acidic group becomes a self-water-dispersible resin toner by neutralizing the acidic group. The resin having self-water dispersibility increases hydrophilicity due to the acidic group becoming an anionic toner and is dispersed in an aqueous medium (water or a liquid medium containing water as a main component). The base used to neutralize the acidic group is not particularly limited, for example sodium hydroxide,
Inorganic bases such as potassium hydroxide and ammonia, and organic bases such as diethylamine, triethylamine and isopropylamine are used.

When the white pigment dispersion consisting of the binder resin (2), the colorant and the organic solvent is mixed with an aqueous medium in the presence of a base and emulsified, a phase inversion accelerator is added. Is preferred. The phase inversion accelerator refers to an agent having a phase inversion promoting function. That is, in the step of adding an aqueous medium (water or a liquid medium containing water as a main component) to the white pigment dispersion, by gradually adding water to the organic continuous phase of the white pigment dispersion containing an organic solvent, A water-in-oil discontinuous phase is generated, and by further adding water, the water-in-oil discontinuous phase is inverted,
A suspension is formed in which the white pigment dispersion is suspended as particles (droplets) in the aqueous medium. At this time, Water in
The phase inversion accelerator is referred to as a compound having a function of more smoothly promoting the phase inversion from the oil discontinuous phase to the oil in water discontinuous phase.

The following phase inversion accelerators can be used. Alcohol solvent Metal salt compound

Alcohol solvents include methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, t-butanol, sec.
-Butanol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether and the like can be used. Of course, other types can also be used. Among them, preferred are those which are dissolved in water and have a low boiling point, isopropanol,
N-propanol is preferred. The amount of the alcohol solvent used is generally 10 to 50 per 100 parts by weight of the resin solid content.
Although it is about parts by weight, of course, it is not limited to this amount.

As the metal salt compound, known compounds can be used, but those having a valence of 2 or more and soluble in water are preferable. Examples thereof include barium chloride, calcium chloride, cuprous chloride, cupric chloride, ferrous chloride and ferric chloride. The amount of metal salt compound used is 100 resin solids.
It is about 0.01 to 3 parts by weight per part by weight, but it is not limited to this amount.

In the present invention, it is preferable to introduce a crosslinked structure into the binder resin (2) after emulsifying the white pigment dispersion. By doing so, when the white resin particles and the binder resin (1) are melt-kneaded, the binder resin (2) is not melted, and the white pigment in the white resin particles is contained in the binder resin (1). There will be no transition. Further, since the crosslinked binder resin (2) has high mechanical strength, it is almost free from cracking when pulverized after melt-kneading. Therefore, the exposure of the white pigment encapsulated in the binder resin (2) on the surface of the toner particles can be reduced as much as possible. Further, the white resin particles produced in the second step become spherical resin particles, but by introducing a crosslinked structure into the binder resin (2), the spherical shape is maintained even during melt-kneading. Spherical particles are advantageous in that they are uniformly dispersed in the binder resin (1), and a white toner having a high concentration and hiding power can be produced with a smaller amount of use as compared with particles that are not crosslinked. it can. White resin particles produced by cross-linking the binder resin (2) are melt-kneaded in the binder resin (1) and crushed to obtain spherical white resin particles uniformly in the binder resin (1). It becomes dispersed toner. The method of crosslinking the binder resin (2) of the white resin particles used in the present invention includes, for example, the following methods.

As a production example in which a crosslinked structure is introduced into the particles, JP-A-9-292737 discloses the details of the production method using a styrene-acrylic resin and a polyester resin. The method described in the publication can also be used in the present invention as a method for crosslinking the binder resin (2) of white resin particles. The cross-linking method described in the publication is described below.

As a method of crosslinking the binder resin (2), it is preferable to carry out a reaction between a functional group in the resin and a crosslinking agent. For example, when the functional group of the resin is a carboxyl group, as a cross-linking agent that reacts with the carboxyl group to cross-link the resin, an aminoplast resin, a compound having an average of two or more glycidyl groups in one molecule, and one molecule in one molecule To 1,
A compound having an average of 2 or more 3-dioxolan-2-on-4-yl groups, and an average of 2 carbodiimide groups in one molecule.
A compound having at least two (for example, carbodilite; a carbodiimide group-containing cross-linking agent manufactured by Nisshinbo Co., Ltd.), a compound having an average of two or more oxazoline groups in one molecule, a metal chelate compound, and the like are used. When the functional group of the resin is a hydroxyl group, examples of the crosslinking agent that reacts with the hydroxyl group include:
Aminoplast resin, polyisocyanate compound, blocked polyisocyanate resin and the like are used.

A preferred example of crosslinking the binder resin (2) is a combination of a resin containing a carboxyl group as a functional group and a compound having an average of two or more glycidyl groups in one molecule. Examples of the compound having an average of two or more glycidyl groups in one molecule include bisphenol A type epoxy resin, bisphenol F type epoxy resin,
Glycidyl ethers of phenols such as hydrogenated bisphenol A type epoxy resin and cresol novolac type; various glycols and polyols such as neopentyl glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane diglycidyl ether, sorbitol polyglycidyl ether Glycidyl ethers; glycidyl esters such as adipic acid diglycidyl ester and phthalic acid diglycidyl ester; vinyl-based copolymers obtained by copolymerizing polymerizable monomers having a glycidyl group such as glycidyl (meth) acrylate; epoxidized polybutadiene Glycidylamine compounds such as diglycidylaniline, triglycidylparaaminophenol, tetraglycidylaminodiphenylmethane, etc. It is.

The reaction between the binder resin (2) and the cross-linking agent is preferably carried out in an aqueous medium, and therefore the cross-linking reaction is carried out below the boiling point of water. In particular, in order to avoid fusion between the encapsulated particles, it is preferable to carry out the reaction in the vicinity of the glass transition temperature of the binder resin (2). As the crosslinking agent capable of reacting with the carboxyl group under such a relatively low temperature condition, a glycidylamine compound having a glycidyl group represented by the following formulas 1 and 2 is preferable.

[0045]

[Chemical 1] (Equation 1)

[0046]

[Chemical 2] (Formula 2) (In the formulas 1 and 2, R ₁ and R ₂ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aromatic ring group which may have a substituent or an alicyclic group which may have a substituent. And R ₃ represents an alkyl group having 1 to 4 carbon atoms.)

As the cross-linking agent having the above structure, for example, N, N, N ', N'-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, Examples include N, N-diglycidylbenzylamine, N, N-diglycidyl-α-phenylethylamine, N, N, N ′, N′-tetraglycidylisophoronediamine, and the like.

The reaction ratio in the case of reacting the binder resin (2) with the crosslinking agent is not particularly limited, but in the case where the functional group is a carboxyl group as an example, 1.0 equivalent of a carboxyl group is used. In contrast, the glycidyl group is 0.001-
It is preferable to use a compound having an amount of the glycidyl group in the range of 1.0 equivalent, and when the amount of the glycidyl group is less than 0.001 equivalent to 1.0 equivalent of the carboxyl group, the high molecular weight or the crosslinking is insufficient. Is not preferable.

When a glycidylamine compound and other glycidyl group-containing compounds are used as the crosslinking agent, 2-
A known catalyst such as methylimidazole may be used, or a method in which a secondary monoamine such as dibutylamine is added to a part of the glycidyl group to impart autocatalytic ability to the glycidyl group-containing compound.

The acid value of the binder resin (2) is preferably 10 to 150, more preferably 30 to 100, and 40 to 40.
80 is more preferred. When the acid value is lower than 10, the dispersibility in an aqueous medium is lowered, which causes a problem in producing white resin particles. Furthermore, when the crosslinking reaction is carried out using the carboxyl group in the binder resin (2), it is not preferable because the resin does not have a high molecular weight or the crosslinking density is lowered. Further, if the acid value is higher than 150, the hygroscopicity of the white resin particles becomes high, which is not preferable.

The binder resin (2) preferably has a glass transition temperature measured by DSC (differential scanning calorimeter) of 50 ° C. or higher, more preferably 60 ° C. or higher and 110 ° C. or lower. T before the crosslinking reaction of the binder resin (2)
The weight average molecular weight of the HF-soluble component (value measured by polystyrene conversion gel permeation chromatography) is preferably in the range of 5,000 to 300,000,
The range of 000 to 150,000 is more preferable. When the weight average molecular weight is less than 5,000, the amount of the resin that dissolves in the aqueous medium after dispersion in the aqueous medium increases, and the yield of the white resin particles tends to decrease, and the crosslinking reaction does not proceed sufficiently. However, the resin strength tends to be insufficient, which is not preferable. Further, if the weight average molecular weight is larger than 300,000, it tends to be difficult to disperse in an aqueous medium, which is not preferable.

Further, JP-A-5-148434 describes a method for producing crosslinked fine particles made of urethane / urea resin. According to the publication, a method is described in which an isocyanate-terminated urethane prepolymer is used as a binder resin (2), and an amine is used as a crosslinking agent to crosslink the resin. Also in the present invention, white resin particles can be produced by the method described in the publication.

The third step is a step of separating the obtained white resin particles from the aqueous medium and drying. The method of separating the white resin particles from the aqueous medium and drying is not particularly limited, and a conventionally known method can be used. The dispersion of white resin particles obtained in the second step,
In the third step, for example, dust such as resin pieces and coarse particles are removed by passing through a wet vibrating sieve, and solid-liquid separation can be performed by a known conventional means such as a centrifuge, a filter press, or a belt filter. When the volume average particle diameter of the obtained white resin particles is small, it is preferable to perform solid-liquid separation by a skimming method using a non-hole type centrifuge.

As the drying method, any known and commonly used method can be adopted. For example, a method of drying under normal pressure or reduced pressure at a temperature at which the white resin particles are not heat-fused or aggregated, a method of freeze-drying, and the like can be mentioned. Further, a method of simultaneously separating and drying the colorant-containing white resin particles from the aqueous medium using a spray dryer or the like can be mentioned. In particular, a method of agitating and drying the powder under reduced pressure while heating at a temperature at which the fine particles do not heat-bond or agglomerate, or a flash-jet dryer (Seishin Enterprise Co. The method using a company) is efficient and preferable. The powder of the white resin particles after drying is preferably crushed into aggregates with a mixing stirrer such as a Henschel mixer.

The water content after drying is 5 to 40.
It is preferably within the range of weight%. When the water content is 5% by weight or less, aggregation of the white resin particles becomes strong and crushing becomes difficult, which is not preferable. Further, if the water content exceeds 40% by weight, water is mixed in, which makes the subsequent melt-kneading with the binder resin (1) uneven, which is not preferable.

The white resin particles produced by the above method are melt-kneaded together with the binder resin (1) described above, and then,
Crush and classify to obtain toner. Specifically, for example, the binder resin (1), the white resin particles and, if necessary, various additives are premixed with a Henschel mixer or the like, and then, two-roll, three-roll, pressure kneader. Alternatively, it is melt-kneaded by a kneading means such as a twin-screw extruder. On this occasion,
It suffices that the white resin particles are uniformly dispersed in the binder resin (1), and the conditions for melt kneading are not particularly limited, but are usually 80 to 180 ° C. and 30 seconds to 2 hours. Since the pigment is already finely dispersed in the white resin particles, the melt-kneading conditions are easier than in the case of using untreated pigment powder. Then, after cooling it, it is finely pulverized by a pulverizer such as a jet mill and classified by an air classifier or the like. The average particle size of the toner is not particularly limited, but is usually adjusted to be 5 to 15 μm.

Examples of the white pigment used in the present invention include titanium dioxide, zinc oxide, zirconium oxide and antimony oxide. Of these, white rutile titanium dioxide is particularly preferable. These white pigments generally range from 0.01 to
It is desirable to have a particle size of 2 μm, especially 0.1-0.5 μm. The content of white pigment is
It is preferably 10 to 70% by weight. Above all 2-6
More preferably 0% by weight, 30-60% by weight
Is particularly preferable. In order to have sufficient hiding power (whiteness) as a white toner, it is preferably 10% by weight or more. Further, when it is within 70% by weight, a better fixing property can be obtained.

In the present invention, conventionally known pigments may be used in combination with the white pigment within the range not impairing the gist of the present invention. Examples of such pigments include carbon blacks such as furnace black, channel black, acetylene black, thermal black and lamp black, which are classified by the manufacturing method as black pigments, or C.I. I. Pigment Bl
ack 11 iron oxide pigment, C.I. I. Pigmen
Examples thereof include iron-titanium oxide-based pigment of t Black 12, phthalocyanine-based cyanine black BX and the like.

Examples of blue pigments include phthalocyanine-based C.I. I. Pigment Blue 1, 2, 15: 1,
15: 2,15: 3,15: 4,15: 6,15,1
6, 17: 1, 27, 28, 29, 56, 60, 63 and the like. As the bluish colorant, preferably C.I.
I. Pigment Blue 15: 3 (generic name phthalocyanine blue G), 15 (phthalocyanine blue R), 16 (metal-free phthalocyanine blue), 60 (indanthrone blue), most preferably,
C. I. Pigment Blue 15: 3, 60.

As the yellow pigment, for example,
C. I. Pigment Yellow 1, 3, 4,
5, 6, 12, 13, 14, 15, 16, 17, 18,
24, 55, 65, 73, 74, 81, 83, 87, 9
3,94,95,97,98,100,101,10
4,108,109,110,113,116,11
7,120,123,128,129,133,13
8,139,147,151,153,154,15
5,156,168,169,170,171,17
2,173,180,185 etc. are mentioned. Preferably, C.I. I. Pigment Yellow 12 (generic name disazo yellow AAA), 13 (disazo yellow AAMX), 17 (disazo yellow AAO)
A), 97 (Fast Yellow FGL), 110 (Isoindolinone Yellow 3RLT), and 155.
(Sandrin Yellow 4G), 180 (benzimidazolone), most preferably C.I. I. Pigm
ent Yellow 17, 155, 180.

Further, as the red pigment, for example,
C. I. Pigment Red 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 12, 14, 15, 17,
18,22,23,31,37,38,41,42,4
8: 1, 48: 2, 48: 3, 48: 4, 49: 1,4
9: 2, 50: 1, 52: 1, 52: 2, 53: 1, 5
4,57: 1,58: 4,60: 1,63: 1,63:
2, 64: 1, 65, 66, 67, 68, 81, 83,
88, 90, 90: 1, 112, 114, 115, 12
2,123,133,144,146,147,14
9,150,151,166,168,170,17
1,172,174,175,176,177,17
8,179,185,187,188,189,19
0,193,194,202,208,209,21
4,216,220,221,224,242,24
3, 243: 1, 245, 246, 247 and the like. Preferably, C.I. I. Pigment Red 4
8: 1 (generic name barium red), 48: 2 (calcium red), 48: 3 (strontium red), 4
8: 4 (manganese red), 53: 1 (lake red), 57: 1 (brilliant carmine 6B), 122
(Quinacridone magenta 122) and 209 (dichloroquinacridone red), most preferably C.I. I. Pigment Red 57: 1, 122 and 209.

In the present invention, a charge control agent can be used if necessary. For example, as a positive charge control agent, a nigrosine dye, a triphenylmethane dye, a quaternary ammonium salt, a resin containing a quaternary ammonium group and / or an amino group, or the like is used as a negative charge control agent, a trimethylethane dye, or a metal of salicylic acid. Complex salts, metal complex salts of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex salts azo dyes, acid dyes containing heavy metals such as azochrome complexes, calixarene type phenolic condensates, cyclic polysaccharides, carboxyl groups And / or resins containing sulfonyl groups.

Particularly in the present invention, it is desirable to use a colorless charge control agent, and as the negative charge control agent, "Bontron E-84" manufactured by Orient Chemical Co. is used as a metal complex compound of salicylic acid. Examples of positive charge control agents include TP-302 and TP-4 having a quaternary ammonium salt structure.
15, TP-610; (manufactured by Hodogaya Chemical Co., Ltd.), Bontron P
-51; (manufactured by Orient Chemical), Copy Charge PSY
(Clariant Japan) and the like are preferably used. In addition, as a positively chargeable resin type charge control agent containing a quaternary ammonium group and / or an amino group, “FCA-20
1-PS ”(Fujikura Kasei Co., Ltd.) and the like.

Among them, as the charge control agent which can be particularly preferably used in the present invention, a compound represented by the following formula 3,
And a compound of formula 4.

[0065]

[Chemical 3] (Formula 3) (In the formula, R ₁ is quaternary carbon, methine, or methylene;
N, S, O, P may contain a hetero atom, Y represents a cyclic structure connected by a saturated bond or an unsaturated bond, and R
₂ , R ₃ are each independently an alkyl group, an alkenyl group,
Alkoxy group, optionally substituted aryl group or aryloxy group, aralkyl group or aralkyloxy group, halogen group, hydrogen, hydroxyl group, optionally substituted amino group, carboxyl group, carbonyl group, nitro Base,
Represents a nitroso group, a sulfonyl group, a cyano group, R ₄ represents hydrogen or an alkyl group, t is an integer of 0 to 1 to 12, m is an integer of 1 to 20, n is an integer of 0 to 1 to 20, k Is an integer of 0 to 1 to 4, p is an integer of 0 to 1 to 4, q is an integer of 0 to 1 to 3, r is an integer of 1 to 20, and s is 0 or an integer of 1 to 20. )

[0066]

[Chemical 4] (Formula 4) (In the formula, R ₁ and R ₄ represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ represent a substituted or unsubstituted aromatic ring ( (Including a condensed ring), M represents one trivalent metal selected from B, Al, Fe, Ti, Co and Cr, and X ⁺ represents a cation).

Specific examples of the compound of the formula 3 include the following <charge control agent 1> to <charge control agent 3>.

[0068]

[Chemical 5] <Charge control agent 1>

[0069]

[Chemical 6] <Charge control agent 2>

[0070]

[Chemical 7] <Charge control agent 3>

Further, specific examples of the compound of the formula 4 include the following <charge control agent 4> and <charge control agent 5>.

[0072]

[Chemical 8] <Charge control agent 4>

[0073]

[Chemical 9] <Charge control agent 5>

The above charge control agents may be used alone or in combination, and are added in an amount of 0.3 in 100 parts by weight of the toner.
-15 parts by weight, preferably 0.5 to 5 parts by weight can provide good charging performance.

Further, in the present invention, in the heat roll fixing application, various waxes are used as necessary as an auxiliary agent for enhancing the releasing effect for the purpose of preventing troubles due to the toner sticking to the heat roll (offset). It Natural waxes such as montanate waxes,
Polyolefin wax such as high pressure polyethylene and polypropylene can be used.

Among the above, carnauba wax, montan ester wax, rice wax and / or scale wax are particularly preferably used in the present invention. These waxes show the best dispersibility in the polyester resin having the structure according to the present invention, and the fixability and the offset resistance are remarkably improved.

As carnauba wax, it is preferable to use free fatty acid type carnauba wax from which free fatty acids have been removed by purification. The acid value of the free fatty acid type carnauba wax is preferably 8 or less, more preferably 5 or less. The free fatty acid type carnauba wax becomes a microcrystalline toner as compared with the conventional carnauba wax, and the dispersibility in the polyester resin is improved. The montan ester wax is refined from minerals, and by refining, it becomes microcrystalline like carnauba wax, and dispersibility in the polyester resin is improved. The acid value of the montan ester wax is preferably 30 or less.

The rice wax is a refined rice bran wax, and preferably has an acid value of 13 or less. The scale bug wax can be obtained by, for example, dissolving a waxy component secreted by larvae of scale insects (also known as rotifer) in hot water, separating the upper layer and then cooling and solidifying, or repeating the process. The scale insect wax purified by such means is white in a solid state, has an extremely sharp melting point, and is suitable as a wax for toner in the present invention. The acid value becomes 10 or less by purification, and 5 is preferable for toner.
It is the following.

The above waxes may be used alone or in combination and are added in an amount of 0.3 to 15 in 100 parts by weight of the toner.
Good fixing offset performance can be obtained by containing 1 part by weight, preferably 1 to 5 parts by weight. If the amount is less than 0.3 parts by weight, the offset resistance is impaired, and if the amount is more than 15 parts by weight, the fluidity of the toner is deteriorated, and the spent carrier is generated due to the adhesion to the carrier surface, which adversely affects the charging characteristics of the toner. Will be given.

In addition to the above natural wax, synthetic ester wax can be preferably used. Among synthetic ester waxes, there is tetrabehenic acid ester of pentaerythritol and the like. A synthetic wax such as polypropylene wax or polyethylene wax can also be used in combination.

External additives may be added to the toner produced by the production method of the present invention by using a mixer such as a Henschel mixer. The external additive is, for example, one used for improving the fluidity of the toner, surface modification of the toner such as improvement of charging characteristics, such as silica, titanium oxide,
Inorganic fine powders such as aluminum oxide, cerium oxide, zinc oxide, tin oxide and zirconium oxide, and those obtained by surface-treating them with a hydrophobizing agent such as silicone oil and a silane coupling agent can be preferably used. If necessary, resin fine powder such as polystyrene, acryl, styrene acryl, polyester, polyolefin, cellulose, polyurethane, benzoguanamine, melamine, nylon, silicone, phenol and vinylidene fluoride can be used.

Specific examples of silica used as an external additive include:
Some products are sold under the following trade names. AEROSIL; R972, R974, R202, R8
05, R812, RX200, NAX50, RX20
0, RY50, RY200, R809, RX50, R
A200HS, RA200H [Japan Aerosil Co., Ltd.] WACKER; HDK H2000, H2050, H3
050, HVK2150 [Wacker Chemicals Co., Ltd.], HDK H13TM, HDK H13TD, HDK H
13TX [Clariant Japan] Nipsil; SS-10, SS-15, SS-20,
SS-50, SS-60, SS-100, SS-50
B, SS-50F, SS-10F, SS-40, SS-
70, SS-72F, [Nippon Silica Industry Co., Ltd.], CABOSIL; TS-500, TS-530, TS-
610, TS-720, TG-308F, TG-709
F, TG-810G, TG-811F, TG820F
[Cabot Specialty Chemicals, Inc.], etc.

The titanium oxide may be a hydrophilic grade or a hydrophobic grade whose surface is treated with octylsilane or the like. For example, there are commercially available products with the following trade names. Titanium oxide T
805 [Degussa Co., Ltd.], titanium oxide P25 [Japan Aerosil Co., Ltd.] and the like. Examples of alumina include aluminum oxide C [Degussa Co., Ltd.] and the like.

The particle diameter of these external additives is preferably 1/3 or less of the diameter of toner particles, and particularly preferably 1
/ 10 or less. Further, in the present invention, two or more kinds of external additives having different average particle diameters may be used in combination as the external additives.

Particularly when used as a non-magnetic one-component developing toner, the toner fluidity and the developing durability are improved by using a toner having a large particle diameter and a toner having a small particle diameter together. It is preferable because it can prevent blade sticking and fogging, and can provide long-term stability of charging during running. The external additive is used in an amount of 0.05 to 5% by weight, preferably 0.1 to 3% by weight, based on 100 parts by weight of the toner.
Within the range of.

The toner produced by the manufacturing method of the present invention can be used as a two-component developer in combination with a carrier. Iron powder, magnetite, ferrite, etc., which are used in the usual two-component developing method, can be used as the core agent of the carrier, but among them, the true specific gravity is low, the resistance is high, the environmental stability is excellent, and it is easy to form a sphere, so the fluidity is high. Good ferrite or magnetite is preferably used. The shape of the core agent may be spherical, amorphous or the like, and may be used without any particular problem. The average particle diameter is generally 10 to 500 μm, but in order to print a high resolution image, it is in the range of 30 to 120 μm, more preferably 60 to 100 μm.

Examples of coating resins for coating these core agents include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylcarbazole, polyvinyl ether polyvinyl ketone, vinyl chloride. / Vinyl acetate copolymer, styrene / acrylic copolymer, straight silicone resin consisting of organosiloxane bond or modified product thereof, fluororesin, (meth) acrylic resin,
Polyester, polyurethane, polycarbonate, phenol resin, amino resin, melamine resin, benzoguanamine resin, urea resin, amide resin, epoxy resin and the like can be used. Among these, silicone resins, fluororesins, and (meth) acrylic resins are particularly excellent in charging stability and coating strength and can be used more preferably. That is, the resin-coated carrier used in the present invention is a resin-coated magnetic carrier that uses ferrite or magnetite as a core agent and is coated with one or more resins selected from silicone resin, fluororesin, and (meth) acrylic resin. It is preferable. Silicone resin is particularly preferable as the coating resin.

As the resistance control agent dispersed in the above resin, carbon black such as acetylene black, channel black, furnace black and Ketjen black, metal carbide such as SiC and TiC, BN and Nb.
N, metal nitride such as TiN, MoB, CrB, TiB ₂
And the like, metal oxides such as ZnO, PiO ₂ , and SnO ₂ , and fine metal powders such as Al and Ni can be used. The number average diameter of the resistance control agent is 0.01 to 5 μm,
It is preferably about 0.05 to 3 μm. It is measured by transmission electron microscopy.

The weight ratio of the toner to the resin-coated magnetic carrier is not particularly limited, but the carrier 10 is usually used.
0.5 to 15 parts by weight of toner per 0 parts by weight.

[0090]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

[0091] (Synthesis Example 1 of Binder Resin (1); R-1)       Terephthalic acid 166 parts by weight       Isophthalic acid 415 parts by weight       Trimellitic acid 96 parts by weight       Polyoxyethylene- (2.0) -2,2       -Bis (4-hydroxyphenyl) propane 1300 parts by weight       75 parts by weight of ethylene glycol

Was placed in a four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 0.07% by weight of dibutyltin oxide was added to the total acid component under a nitrogen gas stream to produce dehydration condensation. 230 while removing water
The reaction was carried out at ℃ for 15 hours. The polyester resin thus obtained has a softening point T1 / 2 of 155 ° C. and a Tg of 6 by the DSC method.
The acid value was 10 at 2 ° C. Hereinafter referred to as R-1.

(Synthesis Example 2 of Binder Resin (1); R-2) Terephthalic Acid 415 parts by weight Isophthalic Acid 415 parts by weight Polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) 1690 parts by weight of propane was placed in a four-necked flask, a stirrer, a condenser, and a thermometer were set, nitrogen gas was blown in, and 0.7 parts by weight of dibutyltin oxide as a catalyst was added to all acid components. The reaction was carried out at 220 ° C. for 10 hours while removing water produced by dehydration condensation. After that, the pressure is sequentially reduced to 5 mmH
The reaction was continued at g. The reaction was followed by the softening point according to ASTM E28-517, and the reaction was terminated when the softening point reached 103 ° C. The linear polyester resin thus obtained had an acid value of 12 and a hydroxyl value of 27. Also,
The softening point T1 / 2 was 105 ° C and the Tg was 62 ° C. The molecular weight is Mw: 9500, Mn: 3600.
Met. Tg was measured by DSC. Below, R-2
Is displayed.

[0094] (Synthesis Example 3 of Binder Resin (1); R-3)       320 parts by weight of styrene       Butyl acrylate 60 parts by weight       Methacrylic acid 20 parts by weight       Azobisisobutyronitrile 4 parts by weight       Xylene 600 parts by weight

C. was charged in a round bottom flask, reacted at 80.degree. C. for about 10 hours in a nitrogen gas atmosphere, and then heated to 130.degree. C. to complete the polymerization. Then, 12 parts by weight of aluminum isopropoxide was added and reacted for about 1 hour.
The solvent was removed by heating to 0 ° C. and reducing the pressure to 0.5 mmHg with a vacuum pump.

The chelate-crosslinking styrene acrylic resin thus obtained had a softening point T1 / 2 of 14 by the ring and ball softening point measuring method.
The Tg by DSC method was 5 ° C, the temperature was 61 ° C, and the acid value was 5. Hereinafter referred to as R-3.

(Synthesis Example of Binder Resin (2); R-4) 114 Parts of Methyl Ethyl Ketone, 12 Isopropyl Alcohol
Parts and 24 parts of water were placed in a reaction vessel and heated to 80 ° C., and then a mixture in the proportions shown below was charged all at once under a nitrogen stream to start the reaction. Acrylic acid 54.0 parts by weight Styrene 364.8 parts by weight Butyl acrylate 181.2 parts by weight Perbutyl O 0.6 parts by weight About 10 parts of the reaction resin solution is sampled every 1 hour after 3 hours from the start of the reaction. Then, it was diluted with the same amount of methyl ethyl ketone, and the viscosity was measured with a Gardner viscometer.
At the time when the viscosity becomes MN, methyl ethyl ketone 567
Part, and a mixed solvent consisting of 63 parts of isopropyl alcohol was added. At this time, the residual monomer ratio was quantified using gas chromatography, and the polymerization ratio was calculated.
It was 1%. After heating the temperature of the reaction solution to 80 ° C.,
The following proportions of the mixture were added dropwise over 1 hour. Acrylic acid 54.0 parts by weight Styrene 456.6 parts by weight Butyl acrylate 89.4 parts by weight Perbutyl O 18.0 parts by weight After completion of the dropping, 2 parts of "Perbutyl O" was added 3 times every 3 hours, and further 4 parts were added. The reaction was allowed to continue for an hour. After the reaction,
This resin solution was heated and degassed to obtain a solid resin (R-4). R-4 had a bimodal molecular weight distribution, and its weight average molecular weight was 110000. When these two mountains are separated at the boundary, the weight average molecular weights are 33,000 and 350.
It could be divided into two parts of 000 and the ratio was 77/22. R-4 has an acid value of 70 and a glass transition temperature of 63 ° C.
Met.

(Preparation Example of White Pigment Dispersion P1) After predispersing 50 parts of the resin (R-4), 50 parts of TITANIX JR-800 (manufactured by Teika, white rutile titanium dioxide) and 185 parts of methyl ethyl ketone with a despar. , Eiger Motor Mill M-1000 (motor mill manufactured by Eiger, USA) was used to obtain a master solution of a white pigment dispersion. Thereafter, methyl ethyl ketone was used to adjust the solid content of the master solution of the white pigment dispersion to 35% by weight. The proportion of pigment in the solid content was 50% by weight.
The white pigment was finely dispersed in the master solution. Furthermore, the obtained master solution 114.3 of the white pigment dispersion.
60 parts of (R-4) was stirred and dissolved with a despar to obtain a white pigment dispersion P1. The obtained white pigment dispersion P1
Was adjusted to a solid content of 55% by weight with methyl ethyl ketone. The proportion of pigment in the solid content was 20% by weight.

(Synthesis example 1 of white resin particles; PR-1) 545.5 parts of white pigment dispersion (P1), 66.7 parts of methyl ethyl ketone, 43 parts of isopropyl alcohol, and 1
40 parts of a 6.4% aqueous sodium hydroxide solution was added and mixed well, and 680 parts of water was added while continuing stirring. Then, the solvent and a part of water were distilled off under reduced pressure to obtain an aqueous slurry of white resin particles. The obtained slurry was subjected to solid-liquid separation by a skimming method using a centrifuge, and the wet cake was freeze-dried to obtain white resin particle powder (PR-1). The pigment content in the white resin particles was 20.1%.

(Synthesis example 2 of white resin particles; PR-2) 545.5 parts of white pigment dispersion (P1), 66.7 parts of methyl ethyl ketone, 43 parts of isopropyl alcohol, Tetrad X (N manufactured by Mitsubishi Gas Chemical Industry Co., Ltd.) , N, N ', N'-
Tetraglycidyl-m-xylenediamine) (7.2 parts) and 16.4% aqueous sodium hydroxide solution (40 parts) were added and mixed well, and 680 parts of water was added while continuing stirring. Then, the solvent and a part of water were distilled off under reduced pressure to obtain an aqueous slurry of white resin particles. Then, the temperature of the slurry was raised to 70 ° C., and the mixture was stirred for 4 hours to carry out a crosslinking reaction of the binder resin (2) (R-4). The obtained slurry was subjected to solid-liquid separation by a skimming method using a centrifuge, and the wet cake was freeze-dried to obtain a powder of white resin particles (PR-2). The pigment content in the white resin particles was 19.8%.

(Preparation Example of White Pigment Dispersion P2) 60 parts of the resin (R-4), 40 parts of TITANIX JR-800 (manufactured by Teika) and 80 parts of methyl ethyl ketone were predispersed with a despar, and then Eiger Motor Mill M- 1000
(Motor mill manufactured by Eiger, USA) was dispersed to obtain a master solution of a white pigment dispersion. Then, it was adjusted to 55% by weight with methyl ethyl ketone, and white pigment dispersion P
Got 2. The proportion of pigment in the solid content was 40% by weight. The white pigment was finely dispersed in the master solution.

(Synthesis Example 3 of White Resin Particles; PR-3) Powder (PR-3) of white resin particles was obtained in the same manner as in Synthesis Example 2 of white resin particles. The pigment content in the white resin particles is 3
It was 9.7%.

(Preparation Example of White Pigment Dispersion P3) 20 parts of the resin (R-4), 80 parts of TITANIX JR-800 (manufactured by Teika) and 80 parts of methyl ethyl ketone were predispersed with a despar, and then Eiger Motor Mill M- 1000
(Motor mill manufactured by Eiger, USA) was dispersed to obtain a master solution of a white pigment dispersion. Then, it was adjusted to 55% by weight with methyl ethyl ketone, and white pigment dispersion P
Got 3. The proportion of pigment in the solid content is 80% by weight,
The white pigment was finely dispersed in the master solution.

(Synthesis example 4 of white resin particles; PR-4) Powder of white resin particles (PR-4) was obtained in the same manner as in Synthesis example 2 of white resin particles. The pigment content in the white resin particles is 7
It was 9.8%.

(Synthesis Example 5 of White Resin Particles; PR-5) "UNICEF PT-200" was placed in a nitrogen-substituted four-necked flask.
0 "(manufactured by Nippon Oil & Fats Co., Ltd.) and 55.5 parts of isophorone diisocyanate were charged and reacted at 120 ° C for 30 minutes, and then 0.05 part of octene suntin was added to the mixture at the same temperature for 60 minutes. After reacting, 80
The temperature was lowered to ℃, 182.5 parts of methyl ethyl ketone and 33.5 parts of dimethylol propionic acid were added, and the temperature was changed to 75 ℃.
When the reaction was carried out for 6 hours, the resin solution (R-
The solid content of 5) was 65% by weight, the acid value was 41.0, and the isocyanate group content was 3.0%.

76.9 parts of this resin solution (R-5) and TI
After premixing 50 parts of TANIX JR-800 (manufactured by Teika) and 53.4 parts of methyl ethyl ketone with a despar,
Dispersion was carried out with an Eiger motor mill M-1000 (motor mill manufactured by Eiger USA) to obtain a master solution of a white pigment dispersion. Then, the solid content of the master solution of the white pigment dispersion was adjusted to 48% by weight using methyl ethyl ketone to obtain a white pigment dispersion P4. The proportion of pigment in the solid content was 50% by weight, and the white pigment was finely dispersed in the master solution. Then, 270.8 parts of this white pigment dispersion (P4) and 41.3 parts of "Bernock 980" (manufactured by Dainippon Ink and Chemicals, Inc.), 31.8 parts of methyl ethyl ketone, and 3.8 parts of triethylamine were added. , Mix well, add 600 parts of water while continuing to stir,
Then, an aqueous solution prepared by dissolving 6.5 parts of diethylenetriamine in 100 parts of water was added. Further, thereafter, the solvent and part of water were distilled off under reduced pressure to obtain an aqueous slurry of white resin particles. Then, solid-liquid separation was performed by a skimming method using a centrifuge, and the obtained wet cake was freeze-dried to obtain white resin particle powder (PR-5). The pigment content in the white resin particles was 36.2%.

(Synthesis Example 6 of White Resin Particles; PR-6) Terephthalic acid 36.9 mol% Isophthalic acid 9.2 mol% Polyoxyethylene- (2.0) -2,2 11.3 mol% -bis (4-hydroxyphenyl) propane polyoxypropylene- (2.0) -2,2 22.5 mol% -bis (4-hydroxyphenyl) propane ethylene glycol 20.1 mol% was added to a stirrer, a condenser, and a thermometer. It was placed in the set four-necked flask, and the total acid component was adjusted to 0.
Dibutyltin oxide (07 parts by weight) was added, and the reaction was carried out at 220 ° C. for 12 hours while removing water produced by dehydration condensation. The obtained polyester resin (R-6) has a softening temperature of 110 ° C. measured by a ring and ball softening point method, and DSC.
The Tg by the method was 57 ° C. and the acid value was 7.

50 parts of the resin (R-6) and TITANI
50 parts of X JR-800 (manufactured by Teika) and 80 parts of methyl ethyl ketone were pre-dispersed with a despar, and then dispersed with an Eiger motor mill M-1000 (motor mill manufactured by Eiger Co., USA) to obtain a master solution of a white pigment dispersion. It was Then, it was adjusted to 40% by weight using methyl ethyl ketone. The proportion of pigment in the solid content was 50% by weight.
The pigment was finely dispersed by wet kneading. Furthermore, the resin (R-
6) 14 parts and the resin (R-1) 6 parts were stirred with a despar to obtain a white pigment dispersion P5. Thereafter, the solid content was adjusted to 55% by weight using methyl ethyl ketone. The proportion of pigment in the solid content was 40% by weight.

Then, the white pigment dispersion (P5) 181.
8 parts and 8 parts carbodilite and 1N ammonia water 6.5
Parts and mix well, while continuing to stir water 12
0 parts was added. Furthermore, after that, under reduced pressure, the solvent,
And part of the water were distilled off to obtain a water slurry of white resin particles. Then, the temperature of the slurry was raised to 80 ° C., and the mixture was stirred for 3 hours to crosslink the binder resin. The obtained slurry was subjected to solid-liquid separation by a skimming method using a centrifuge, and the wet cake was freeze-dried to obtain white resin particle powder (PR-6). The pigment content in the white resin particles was 38.6%.

Table 1 shows the properties of PR-1 to PR-6.

[0111]

[Table 1]

(Comparative Pigment 1) Binder Resin (1) (R-2) 600 parts by weight White Pigment TITANIX JR-800 (manufactured by Teika) 400 parts by weight or more of raw materials are mixed by a Henschel mixer, and then heated by two rolls. Kneaded in. After cooling, pulverization is performed to obtain a pigment content of 4
0% of comparative pigment 1 (masterbatch) was prepared.

(Comparative Pigment 2) Comparative Pigment 2 was prepared in the same manner as Comparative Pigment 1 except that the resin used in Comparative Pigment 1 was R-3.

(Examples 1 to 11) Binder resin (1) shown in Table 2, white resin particles, a release agent, and a charge control agent were mixed in the respective weight ratios described using a Henschel mixer. Then, the mixture was kneaded with a biaxial kneader. The kneaded material thus obtained was pulverized and classified to obtain a "toner raw material" having a volume average particle diameter of 8.8 to 9.3 µm.

Further, regarding the "toner raw material" of Examples 1 to 7, silica H was added to 100 parts by weight of the "toner raw material".
― 2018 (Clariant Co., Ltd.) 1 part by weight and titanium J
0.5 part of MT-150AO (Taika Co., Ltd.) was mixed with a Henschel mixer and externally added. After that, the toner of the example was passed through a sieve. In addition, Examples 8 to 1
For the "toner raw material" of No. 1, "toner raw material" 100
1 part by weight of silica HDK3050EP (Wacker Chemicals Co., Ltd.) was mixed with 1 part by weight with a Henschel mixer and externally added. After that, the toner of the example was passed through a sieve.

(Comparative Examples 1 to 7) Using the binder resin (1) shown in Table 2, the comparative pigment, the release agent and the charge control agent, the volume average particle size was changed in the same manufacturing process as the toner of the example. Diameter 8.7
A "toner stock" of ˜9.2 μm was produced.

Further, in the "toner raw material" of Comparative Examples 1 to 3, silica H was added to 100 parts by weight of the "toner raw material".
― 2018 (Clariant Co., Ltd.) 1 part by weight and titanium J
0.5 part of MT-150AO (Taika Co., Ltd.) was mixed with a Henschel mixer and externally added. Then, it was passed through a sieve to obtain a toner of a comparative example. Moreover, Comparative Examples 4 to 7
As for the “toner raw material”, 1 part by weight of silica HDK3050EP (Wacker Chemicals Co., Ltd.) was mixed with 100 parts by weight of the “toner raw material” by a Henschel mixer, and externally added. Then, it was passed through a sieve to obtain a toner of a comparative example.

[0118]

[Table 2] ・ Carnava: Carnauba wax No. 1 (imported by Yoko Kato) ・ 550P: Viscor 550P (Sanyo Kasei Co., Ltd.)
Polypropylene wax) N07: Bontron N-07 (Orient Chemical Co., Ltd. Nigrosine dye) JR-800: TITANIX JR-800 (Taika Corporation rutile white titanium dioxide)

The following tests were carried out using the toners manufactured in Examples and Comparative Examples. (Measurement of Charge Amount) To measure the amount of charge, a toner prepared by externally adding the “toner raw material” and a ferrite carrier (particle size 90 μm) coated with a silicone resin with a mixing ratio of 4/96 was used to prepare a developer, and a ball mill was used. After stirring for 5 minutes for 30 minutes, the charge amount and the reverse charge amount (number%) of the toner are measured with an E-spurt analyzer (manufactured by Hosokawa Micron Co., Ltd.), which is a charge amount measuring device, and the stirring time is different. The rising property of the toner charge amount was evaluated. The evaluation results obtained are shown in Table 3. Measurement conditions of E-Spurt analyzer Blow pressure: 0.02 MPa Measurement count number: 3000 pieces Potential difference between electrodes: 100 V 25 ° C., 60%

(Environmental stability) A toner was prepared by adding 4/96 of the toner externally added to the "toner raw material" and a ferrite carrier (particle size 90 μm) coated with a silicone resin. The developer was left for 12 hours in each environment of high temperature and high humidity (35 ° C., 85% RH) and low temperature and low humidity (10 ° C., 20% RH). Then, stir in a ball mill for 30 minutes,
The amount of charge was measured by an E-Spurt analyzer. The evaluation results obtained are shown in Table 3.

H / H in the table is high temperature and high humidity (35 ° C., 85%
RH) and L / L represent low temperature and low humidity (10 ° C., 20% RH), and the environmental difference represents an absolute value obtained by subtracting the charge amount of H / H from the charge amount of L / L.

[0122]

[Table 3]

Examples 3 and 6 to 7 and Comparative Examples 1 and 2 are comparisons in negatively charged toner in which a polyester resin is used as a binder resin and the white pigment in the toner is about 20%. Comparing the two, the toner of the example shows a small difference between the values even when the stirring time by the ball mill is compared with 5 minutes and 30 minutes,
Good charge rising property. Regarding the resin of the white resin particles, any of styrene / acrylic resin, urethane / urea resin, and polyester resin showed equivalent characteristics. On the other hand, the toner of the comparative example has a large variation in charging, and the rising property of charging is also poor. Further, regarding the environmental difference, the toner of the example has a smaller environmental difference than the toner of the comparative example.

The same applies when comparing Examples 8 to 10 with Comparative Examples 4 and 5 and Example 11 with Comparative Examples 6 and 7.

Further, in Examples 2 to 5, the content of the white pigment in the toner was changed, but the rising property of charging was good and the environmental difference was small. On the other hand, it can be seen that the composition in which 60% of the titanium oxide of Comparative Example 3 is blended as it is has a low charge amount and has poor environmental characteristics. In addition, although Example 1 uses non-crosslinked white resin particles, it shows almost the same characteristics in charging rising property and environment difference as compared with Example 2.
It is apparent that the effects of the present invention are obtained.

(Evaluation of Concealment Printing) Image density of 1.5 printed on a color printer using a commercially available N-type two-component copying machine.
The cyan, magenta, yellow and black images of No. 1 were overprinted with the above white toner, and the hiding property was evaluated. Concealment is based on Macbeth densitometer RD-918, which is the image density of overprinted images.
The hiding property was judged to be good when the concentration was low. The results are shown in Table 4.

[0127]

[Table 4]

(Toner Scattering State and Charge Amount) Commercially available N
Using a mold two-component copying machine, the charge amount of the developer was measured in the initial printing of 10,000 continuous prints and after the 10,000 prints. In addition, the scattering of toner inside the developing device was visually observed. ○: No scattering is observed State xx
And The results are shown in Table 5. The charge amount was measured by collecting toner from the inside of the developing device and using a blow-off charge amount measuring device (manufactured by Toshiba Chemical). The test results are shown in Table 5.

[0129]

[Table 5]

From Tables 4 and 5, in Examples 1 to 7, the hiding property increased as the white pigment content in the toner increased, and no toner scattering was observed in the apparatus. Comparing Examples 3 and 6 to 7 in which the binder resin is polyester and the white pigment content is about 20% with Comparative Examples 1 and 2, the hiding property is improved when the white resin particles are contained. In Comparative Example 3, the hiding property was good, but the charge amount was low, and therefore a large amount of toner was scattered in the machine.

[0131]

According to the manufacturing method of the present invention, the white pigment is not exposed on the surface of the toner, and even if the toner has a small particle size or a large amount of the white pigment is contained in the toner. It is possible to manufacture a white toner having a high concealing property, which has a stable charge amount and a sharp charge amount distribution.

Claims (8)

[Claims] 1. A method for producing a toner by the steps of kneading a mixture containing a colorant and a binder resin (1) in a molten state, cooling the mixture, and then pulverizing the mixture. As a binder, a white pigment is used as a binder resin (2)
A white pigment characterized by using a white resin particle produced by producing a white pigment dispersion dispersed therein, then emulsifying the white pigment dispersion in an aqueous medium, and further separating from the aqueous medium. Toner manufacturing method. 2. The method for producing a white toner according to claim 1, wherein the white pigment dispersion is wet-dispersed and then emulsified in an aqueous medium. 3. The binder resin (2) is styrene (meth) acrylic resin, urethane resin, urethane urea resin,
Or at least one selected from polyester resins
The method for producing a white toner according to claim 1, comprising at least one resin. 4. The method for producing a white toner according to claim 3, wherein the binder resin (2) contains an acidic group. 5. The method for producing a white toner according to claim 4, wherein the white pigment dispersion is emulsified in an aqueous medium in the presence of a neutralizing agent. 6. The method for producing a white toner according to claim 1, wherein the binder resin (2) is crosslinked after emulsifying the white pigment dispersion in an aqueous medium. 7. The method for producing a white toner according to claim 1, wherein the white pigment is titanium dioxide. 8. The method for producing a white toner according to claim 1, wherein the content of the white pigment is 10 to 70% by weight based on the whole toner.