JPH07325430A - Toner for developing electrostatic latent image and its production - Google Patents

Abstract

PURPOSE:To improve cleanability and electrostatic chargeability by adding calcium phosphate as a dispersion stabilizer to an aq. dispersive liq. used as a dispersive medium for dispersing a resin soln. CONSTITUTION:A bonding resin and a colorant are dissolved and/or dispersed in a water-insoluble org. solvent to prepare a colored resin soln. and this soln. is emulsified and dispersed in an aq. dispersive liq. contg. calcium phosphate as a dispersion stabilizer. The org. solvent is then removed and the calcium phosphate is further removed to produce the objective toner. The calcium phosphate is slightly water-soluble calcium phosphate such as tricalcium phosphate or calcium secondary phosphate. The toner is made almost. free from defectively charged toner particles and has high suitability to the control of the extent of electrostatic charge by an electric charge controlling agent. The desired sufficient extent of electrostatic charge can easily be imparted and satisfactory cleanability and a sharp particle size distribution are ensured.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method for producing an electrostatic latent image developing toner used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, etc., a pulverizing method and a suspension weight method are used. Known methods include a legal method and an emulsion dispersion method.

In the pulverization method, a toner is manufactured by mechanically kneading a resin, a pigment and the like and then pulverizing the mixture. In the suspension polymerization method, a toner is produced by suspending a polymerization composition containing a polymerizable monomer, a polymerization initiator, a colorant and the like in a dispersion medium, and then heating and polymerizing the suspension.

On the other hand, in the emulsification dispersion method, a resin solution obtained by dissolving a resin in a non-water-soluble organic solvent is emulsified and dispersed in an aqueous dispersion to form an emulsion, and heat is applied to the emulsion while stirring. A toner is manufactured by evaporating a non-water-soluble organic solvent and precipitating fine resin particles.

According to the emulsification dispersion method, the process for producing the toner is simplified and the average is 1 to 10 μm in a relatively simple operation.
It is possible to obtain resin fine particles of a certain degree, and the production efficiency is improved and the cost can be reduced at the same time as compared with the pulverization method or the suspension polymerization method. In addition, there are many types of resins that can be used as compared with the suspension polymerization method and the like.

[0006]

However, since the resin fine particles obtained by the emulsion dispersion method are spherical and have a smooth surface, for example, electrophotographic image formation in which the resin fine particles are blade-cleaned is used. When it was used as a toner for the device, it slipped through the blade, resulting in poor cleaning. Further, since the surface area effective for triboelectrification is considered to be small due to the spherical shape, it was difficult to control the triboelectrification property. These problems were remarkable when trying to manufacture a toner having a small particle diameter in order to improve the image quality.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an electrostatic latent image developing toner excellent in cleaning properties and chargeability, which is an electrostatic latent image developing toner produced by an emulsion dispersion method. Another object of the present invention is to provide a method for producing the above electrostatic latent image developing toner.

[0008]

As a result of various studies to solve the above problems, the present inventors have found that calcium phosphate salt as a dispersion stabilizer is added to an aqueous dispersion which is a dispersion medium for dispersing a resin solution. It was found that the shape of the resin fine particles obtained by the emulsion dispersion method can be made amorphous by using the added one.

The reason why the shape of the resin fine particles becomes amorphous by using the calcium phosphate salt as a dispersion stabilizer is not clear, but since the calcium phosphate salt is poorly soluble in water, the resin droplets in the state of particles are formed. It is present at the interface and is considered to hinder the spheroidization of the resin fine particles when the solvent is removed and the resin droplets contract.

The present invention has been made based on such knowledge. That is, the toner for electrostatic latent image development of the present invention is a colored resin solution prepared by dissolving and / or dispersing at least a binder resin and a colorant in a non-water-soluble organic solvent,
This colored resin solution is characterized by being produced by emulsifying and dispersing in an aqueous dispersion containing a calcium phosphate salt as a dispersion stabilizer, removing the water-insoluble organic solvent, and further removing the calcium phosphate salt. .

The method for producing a toner for developing an electrostatic latent image of the present invention comprises a step of dissolving and / or dispersing at least a binder resin and a colorant in a non-water-soluble organic solvent to obtain a colored resin solution, This colored resin solution is emulsified and dispersed in an aqueous dispersion containing a calcium phosphate salt as a dispersion stabilizer to form an O / W emulsion, and a water-insoluble organic solvent is removed from the O / W emulsion. The method is characterized by including a step of obtaining resin fine particles and a step of removing calcium phosphate salt from the resin fine particles.
The O / W type emulsion refers to a suspension in which an oily solution is dispersed as droplets in an aqueous dispersion.

The calcium phosphate salt used in the present invention is a poorly soluble salt of water, and contains tricalcium phosphate,
Examples thereof include dibasic calcium phosphate and hydroxycalcium phosphate. These calcium phosphate salts may be in the form of double salts with calcium fluoride or calcium chloride.

Commercially available calcium phosphate may be used, or crystals obtained by a reaction such as adding sodium phosphate or ammonium phosphate in the presence of ammonia to a soluble calcium salt may be used. .

These calcium phosphate salts are 0.1 to 2
It is preferable to have a particle size in the range of 0 μm.
If the particle size of the calcium phosphate salt is larger than 20 μm, it becomes difficult to obtain droplets having a small particle size. If the particle size is smaller than 0.1 μm, the calcium phosphate salt may agglomerate and the calcium phosphate salt may be incorporated inside the resin fine particles.

In order to obtain the calcium phosphate salt having such a particle size distribution, for example, a commercially available product is pulverized by a wet or dry method, or when the calcium phosphate salt is synthesized,
A method such as adjusting the concentration of the raw material or controlling the pH may be adopted.

The binder resin used in the present invention is not particularly limited as long as it can be dissolved in a water-insoluble organic solvent described later and is insoluble or hardly soluble in water. For example, a styrene resin, ( (Meth) acrylic resin, styrene- (meth) acrylic copolymer resin, olefin resin, polyester resin, polyamide resin, polycarbonate resin, polyether resin, polyvinyl acetate resin, polysulfone resin, epoxy resin, Various known resins such as polyurethane resin and urea resin can be used alone or in combination of two or more.

These binder resins have a glass transition point (T
g) is 50 to 70 ° C. and the number average molecular weight (Mn) is 1000.
~ 50000, preferably 3000-20000, Mn
It is desirable that the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to 2 to 60. T
When g is less than 50 ° C, the heat resistance of the toner is lowered, and Tg is 7
If it exceeds 0 ° C., the fixing property of the toner will be deteriorated. Also, Mn
When it is less than 1000, high temperature offset tends to occur, and when Mn exceeds 50,000, low temperature offset tends to occur. Furthermore, Mw / Mn is 2
If it is less than the range, the non-offset region may become narrow, and if Mw / Mn exceeds 60, low temperature offset is likely to occur. When the toner obtained by the present invention is used as a toner for oil coating and fixing, M
It is desirable that w / Mn be 2 to 5, and when used as an oilless fixing toner, Mw / Mn is 20 to
A value of 50 is desirable.

Examples of the colorant used in the present invention include organic or inorganic pigments of various colors as shown below.

That is, examples of the black pigment include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, magnetite and the like.

Examples of yellow pigments include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G and benzidine yellow. G
R, quinoline yellow rake, permanent yellow N
There are CG and tartrazine rake.

Examples of orange pigments include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, induslen brilliant orange RK, benzidine orange G and induslen brilliant orange GK.

Examples of red pigments include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, resole red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, brilliant carmine 6B, Examples include Eosin Rake, Rhodamine Rake B, Alizarin Rake, Brilliant Carmine 3B.

Examples of purple pigments include manganese purple, fast violet B and methyl violet lake.

As blue pigments, dark blue, cobalt blue, alkali blue lake, Victoria blue lake,
Phthalocyanine blue, metal-free phthalocyanine blue,
Examples include phthalocyanine blue partial chlorinated compounds, fast sky blue, and induslen blue BC.

Examples of green pigments include chrome green, chrome oxide, pigment green B, mica light green lake, and final yellow green G.

As white pigments, zinc white, titanium oxide,
There are antimony white and zinc sulfide.

Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc and alumina white.

These colorants can be used alone or in combination. The colorant is used in an amount of 1 to 20 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the binder resin contained in the toner. If the amount is more than 20 parts by weight, the fixing property of the toner is deteriorated, and if it is less than 1 part by weight, a desired image density may not be obtained.

In the present invention, a charge control agent, magnetic powder,
A component such as an anti-offset agent may be blended in the toner as required.

Examples of the positive charge control agent include nigrosine-based dyes such as Nigrosine base EX (manufactured by Orient Chemical Industry Co., Ltd.), P-51 (manufactured by Orient Chemical Industry Co., Ltd.), and copy charge PX VP435 (manufactured by Hoechst Co.). Primary ammonium salt, alkoxylated amine, alkylamide,
Examples thereof include molybdic acid chelate pigments and imidazole compounds such as PLZ1001 (manufactured by Shikoku Chemicals Co., Ltd.).

As a negative charge control agent, Bontron S-2
2 (manufactured by Orient Chemical Industry Co., Ltd.), Bontron S-34
(Orient Chemical Co., Ltd.), Bontron E-81 (Orient Chemical Co., Ltd.), Bontron E-84 (Orient Chemical Co., Ltd.), Spiron Black TRH (Hodogaya Chemical Co., Ltd.), and other metal complexes, thioindigo. Pigments,
Quaternary ammonium salts such as Copy Charge NX VP434 (manufactured by Hoechst), calixarene compounds such as Bontron E-89 (manufactured by Orient Chemical Industry),
Examples thereof include fluorine compounds such as magnesium fluoride and carbon fluoride.

As the metal complex serving as the negative charge control agent, other than the above-mentioned ones, an oxycarboxylic acid metal complex, a dicarboxylic acid metal complex, an amino acid metal complex, a diketone metal complex, a diamine metal complex, an azo group-containing benzene can be used. It may have various structures such as a benzene derivative skeleton metal complex and an azo group-containing benzene-naphthalene derivative skeleton metal complex.

Each charge control agent is preferably used in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the binder resin contained in the toner. Content of charge control agent is 0.1
If it is less than 5 parts by weight, sufficient charging performance may not be obtained, and if it exceeds 5 parts by weight, a spent may occur at the time of printing endurance, resulting in a decrease in charge amount. It is desirable to use a soluble charge control agent.

Examples of the magnetic powder include magnetite, γ-hematite, various ferrites and the like.

As the anti-offset agent, various waxes can be used, and examples thereof include low molecular weight polypropylene and low molecular weight polyethylene, and polyolefin wax such as oxidized polypropylene and oxidized polyethylene.

In the present invention, the above-mentioned binder resin, colorant, and above-mentioned charge control agent, which is added as necessary,
A colored resin solution is obtained by dissolving or dispersing a toner component such as magnetic powder or an offset preventive agent in a non-water-soluble organic solvent.

The solid content concentration in the colored resin solution is O / which is obtained by emulsifying and dispersing this colored resin solution in an aqueous dispersion.
When removing the water-insoluble organic solvent from the W-type emulsion, it is necessary to set such that the droplets can be easily solidified into fine particles, and therefore 5 to 50% by weight, preferably 10 to 4% by weight.
It is 0% by weight.

The solvent for dissolving and / or dispersing the binder resin and the colorant is not particularly limited as long as it is insoluble or hardly soluble in water and can dissolve the above-mentioned binder resin. , For example, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl. A ketone or the like can be used alone or in combination of two or more kinds. In particular, aromatic solvents such as toluene and xylene and methylene chloride,
Halogenated hydrocarbons such as 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred.

Each toner component is dissolved in a non-water-soluble organic solvent.
In order to disperse, a device such as a ball mill, a sand grinder or an ultrasonic homogenizer can be used.

In the present invention, the colored resin solution thus obtained is emulsified and dispersed in an aqueous dispersion containing a calcium phosphate salt to form an O / W type emulsion.

Examples of the dispersion liquid for dispersing the colored resin solution include water containing the above calcium phosphate salt. Also, instead of water, water containing a water-soluble organic solvent to the extent that does not destroy the emulsion, such as water /
Methanol mixed liquid (weight ratio 50/50 to 100/0), water / ethanol mixed liquid (weight ratio 50/50 to 100/0),
Water / acetone mixture (50 / 50-100 / 0), water / methyl ethyl ketone mixture (weight ratio (70 / 30-100 /
0) or the like may be used.

The calcium phosphate salt contained in the aqueous dispersion is preferably 0.1 to 10% by weight. If the weight of the calcium phosphate salt is less than 0.1% by weight, the liquid droplets cannot be dispersed in a sufficiently stable state, and if it exceeds 10% by weight, the calcium phosphate salts may aggregate.

P of an aqueous dispersion containing calcium phosphate salt
H is adjusted to 5 to 14, preferably 6 to 12. When the pH is lower than 5, the droplets cannot be dispersed in a sufficiently stable state due to the dissolution of the calcium phosphate salt, and when the pH is higher than 14, the calcium phosphate salt is hydrolyzed and the resin solution is also affected. May occur.

In order to adjust the pH of the aqueous dispersion, a method of adding an alkali such as calcium hydroxide or sodium hydroxide or an acid such as hydrochloric acid or phosphoric acid can be employed.

In order to form the O / W emulsion, for example, a method of sufficiently stirring the mixed system of the colored resin solution and the aqueous dispersion using a stirring device such as a homomixer can be adopted. . Since the particle size of each droplet of the colored resin solution in the O / W type emulsion directly affects the size of the finally obtained toner fine particles,
It is necessary to form droplets according to the size of the toner fine particles to be obtained and to sufficiently control the particle size distribution. For example, if a homomixer is used, the rotation speed can be adjusted appropriately. The particle size of the droplet can be easily controlled. If the stirring time is too short, the size of each droplet will be different and a sharp particle size distribution cannot be obtained. Therefore, the stirring time is preferably 10 minutes or more.

The ratio (Vp / Vw) of the volume (Vp) of the colored resin solution to the volume (Vw) of the aqueous dispersion is Vp /
Vw ≦ 1, preferably 0.3 ≦ Vp / Vw ≦ 0.7. When Vp / Vw> 1, a stable O / W type emulsion cannot be formed, and a phase transition occurs in the middle of
There is a high possibility that an / O-type emulsion will be formed.

Since the calcium phosphate salt is poorly soluble in water, it cannot completely cover the surface of the droplets. Therefore, a dispersion stabilizing auxiliary is added to the aqueous dispersion to ensure the dispersion of the colored resin solution. Preferably.

Examples of dispersion stabilizing aids include natural surfactants such as saponins, nonionic surfactants such as alkylene oxides, glycerins, and glycidols, carboxylic acids, sulfonic acids, phosphoric acid, sulfuric ester groups, phosphoric acid. Anionic surfactants containing an acidic group such as an ester group can be used. In particular, when calcium phosphate salt is used as the dispersion stabilizer, it is preferable to use an anionic surfactant as the dispersion stabilization auxiliary agent.

In the present invention, resin fine particles are obtained by removing the non-water-soluble organic solvent from the droplets of the O / W type emulsion.

In order to remove the non-water-soluble organic solvent, it is possible to employ a method in which the whole system is gradually heated to completely remove the non-water-soluble organic solvent in the droplets to form fine toner particles. it can. Alternatively, it is also possible to spray the emulsion in a dry atmosphere to completely remove the non-water-soluble organic solvent in the droplets to form toner fine particles, and to evaporate and remove the aqueous dispersion together.

In the present invention, the calcium phosphate salt adhering to the surface of the resin fine particles thus obtained is removed. For this purpose, it is possible to employ a method in which an acid such as hydrochloric acid, sulfuric acid, nitric acid is added to dissolve the calcium phosphate salt, followed by washing.

After removing the calcium phosphate salt, further washing, drying, and if necessary, classification, etc., the average particle size is 2 to 15 μm, preferably 4 to 10 μm.
m toner for electrostatic latent image development.

[0053]

EXAMPLES The present invention will be described in more detail below with reference to examples. The parts shown below are parts by weight.

<Example 1> Polyester resin (NE-3
82: manufactured by Kao Corporation) 100 parts was dissolved in 400 parts of toluene. Then, 6 parts of a phthalocyanine pigment and 2 parts of a zinc metal complex (E-84: manufactured by Orient Chemical Industry Co., Ltd.) were added, put in a ball mill and mixed and dispersed for 3 hours to prepare a colored resin solution.

On the other hand, p containing 4% by weight of calcium hydroxide phosphate (average particle size 4.5 μm) as a dispersion stabilizer.
An aqueous dispersion was prepared by dissolving 0.1 part of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) in 1000 parts of an aqueous solution of H10.

The above colored resin solution was suspended in this aqueous dispersion using a TK Auto Homomixer (made by Tokushu Kika Kogyo Co., Ltd.). At this time, adjust the rotation speed of the homomixer,
A droplet having an average particle size of 3 to 12 μm was formed.

The resin suspension thus obtained was mixed with 60-65
Toluene was removed from the droplets by leaving the mixture at 70 ° C. and 70 to 140 mmHg for 5 hours, and the calcium hydroxide phosphate was dissolved with concentrated hydrochloric acid, and filtration / washing with water was repeated. Then, it was dried by a slurry dryer (Dispercoat: manufactured by Nisshin Engineering Co., Ltd.) to obtain a toner 1 having an average particle size of 6 μm.

Example 2 1000 parts of an aqueous solution having a pH of 9 and containing 1.5% by weight of calcium hydroxide phosphate (average particle size 3.2 μm) as a dispersion stabilizer was mixed with 0 parts of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.). A resin suspension was obtained by the same procedure as in Example 1 except that an aqueous dispersion was prepared by dissolving 1 part.

After adding 500 parts of an aqueous solution of pH 9 containing 5% by weight of calcium hydroxide phosphate (average particle size 5.0 μm) to the resin suspension thus obtained, the same procedure as in Example 1 was carried out. Toner 2 having an average particle size of 6 μm was obtained.

Example 3 After filtration / washing with water of resin particles,
0.1% by weight of calcium hydroxide phosphate (average particle size 2.
Toner 3 was obtained by the same procedure as in Example 1 except that 1000 parts of an aqueous solution having a pH of 8 containing 3 μm) was added, heated, kept at 70 ° C. for 1 hour, and then dried.

Example 4 6 parts of a quinacridone pigment was used in place of the phthalocyanine pigment, and 1000 parts of an aqueous solution of pH 10 containing 5% by weight of calcium hydroxide phosphate (average particle size 5.0 μm) as a dispersion stabilizer was added to dodecyl. A toner 4 having an average particle size of 7 μm was obtained by the same procedure as in Example 1 except that 0.1 part of sodium benzenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved to prepare an aqueous dispersion.

Example 5 Styrene-butyl methacrylate resin (softening point 121 ° C., Tg 65 ° C., Mn = 230
100 parts of 0, Mw / Mn = 8.5) were dissolved in 400 parts of dichloromethane. Then, 6 parts of a phthalocyanine pigment and 2 parts of a chromium metal complex (TRH: Hodogaya Chemical Co., Ltd.) were added, put in a ball mill and mixed and dispersed for 3 hours to prepare a colored resin solution.

This colored resin solution was suspended in 1000 parts of an aqueous solution of pH 9 containing 2% by weight of dibasic calcium phosphate (average particle size 5.8 μm) as a dispersion stabilizer by the same procedure as in Example 1. It was

After adding 500 parts of an aqueous solution of pH 8 containing 4% by weight of dibasic calcium phosphate (average particle size 5.8 μm) to the resin suspension thus obtained, Example 1
A toner 5 having an average particle diameter of 7 μm was obtained by the same procedure as described above.

<Example 6> Polyester resin (softening point 1
23 ° C., Tg 65 ° C., Mn = 11000, Mw / Mn =
15) 100 parts was dissolved in 400 parts dichloroethane.
Then, 6 parts of Brilliant Carmine 6B and 2 parts of a charge control agent (LR-147: manufactured by Nippon Carlit Co., Ltd.) were added, and the mixture was placed in a ball mill and mixed for 3 hours to disperse the colored resin solution.

On the other hand, an aqueous solution of pH 12 containing 4% by weight of calcium hydroxide phosphate and dicalcium phosphate mixed salt (average particle diameter 3.0 μm) as a dispersion stabilizer.
To 0 parts, 0.1 potassium dodecyl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.)
An aqueous dispersion was prepared by dissolving parts.

Using these, a toner 6 having an average particle size of 8 μm was obtained in the same procedure as in Example 1.

<Example 7> Polyester resin (softening point 9
4 ° C., Tg 65 ° C., Mn = 3400, Mw / Mn = 2.
3) After dissolving 100 parts in 400 parts of toluene, 5 parts of quinacridone pigment was added, put in a ball mill and mixed for 3 hours. Furthermore, a colored resin solution was prepared by adding 2 parts of a zinc metal complex (E-84: manufactured by Orient Chemical Industry Co., Ltd.) dissolved in 20 parts of acetone in advance and stirring vigorously.

On the other hand, to 1000 parts of an aqueous solution having a pH of 11 containing 1.5% by weight of calcium hydroxide phosphate (average particle size 3.0 μm) as a dispersion stabilizer, sodium dodecylbenzenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.) was added. An aqueous dispersion was prepared by dissolving 1 part.

Using these, a resin suspension was obtained in the same procedure as in Example 1, and then 5% by weight of calcium hydroxide phosphate (average particle size 6.5 μm) was added to the resin suspension.
After the addition of 500 parts of an aqueous solution containing 6 and a pH of 6, toner 7 having an average particle size of 6 μm was obtained by the same procedure as in Example 1.

<Comparative Example 1> Hydroxypropyl methylcellulose (Metroose 65SH-5 as a dispersion stabilizer.
0: manufactured by Shin-Etsu Chemical Co., Ltd.) and 10 parts of sodium dodecyl sulfate in 1000 parts of an aqueous solution were used as an aqueous dispersion, except that a toner 8 having an average particle diameter of 6 μm was prepared in the same manner as in Example 1. Got

Comparative Example 2 To 1000 parts of an aqueous solution containing 4% by weight of polyvinyl alcohol (Poval PA-18: manufactured by Shin-Etsu Chemical Co., Ltd.) as a dispersion stabilizer, 0.1 part of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) was added. A toner 9 having an average particle diameter of 6 μm was obtained by the same procedure as in Example 1 except that a solution in which parts were dissolved was used as the aqueous dispersion.

<Comparative Example 3> 4% by weight of sodium polyacrylate as a dispersion stabilizer (polymerization degree: 2500 to 600)
0) containing 1000 parts of an aqueous solution containing 0.1 part of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) was used as an aqueous dispersion except that an average particle size of 6 μm was obtained. Toner 10 was obtained.

<Evaluation of Various Properties> With respect to the toners of Examples and Comparative Examples obtained as described above, various properties were evaluated as follows.

(1) Observation by Electron Microscope The toners of Examples and Comparative Examples were observed by an electron microscope. As an example, in FIG.
An electron micrograph at a magnification of 000 is shown. In addition, in FIG.
An electron micrograph of the toner of Comparative Example 1 at a magnification of 5,000 is shown. Both figures show particles having a size of about 5 μm.

All of the examples were not spherical, but had a shape in which the surface was depressed as shown in FIG.
On the other hand, all of the comparative examples were spherical as shown in FIG.

(2) Measurement of Toner Particle Size For the toners obtained in the above Examples and Comparative Examples,
The volume average particle diameter (Dv) and number average particle diameter (Dp) were measured using a Coulter Multisizer (manufactured by Coulter). Further, the sharpness (Dv / Dp) of the particle size distribution represented by the ratio of Dv and Dp was calculated.

(3) Measurement of charge amount In order to evaluate the characteristics of each toner of Examples and Comparative Examples,
With respect to 100 parts of each toner of Examples and Comparative Examples, 0.3 part of hydrophobic silica (H-2000: manufactured by Wacker) and hydrophobic titanium oxide (T-805: manufactured by Nippon Aerosil Co., Ltd.)
0.5 part was added, and post-treatment was performed for 1 minute at 1000 rpm using a Henschel mixer (manufactured by Mitsui Miike Kakoki Co., Ltd.). The toner thus post-treated and the particle size of 60 μm
A developer for evaluation was prepared by mixing the ferrite particles of No. 1 with a carrier coated with a silicon resin in a thickness of about 1 μm at a weight ratio of 5:95.

30 g of this developer was put in a polyethylene bottle having a capacity of 50 ml, rotated at 1200 rpm for 10 minutes, and then brought into contact with a film charged to a predetermined potential, and the weight of the toner attached to the film was measured. Thus, the charge amount of the toner was obtained.

(4) Measurement of Amount of Inadequately Charged Toner 3 g of the developer prepared and stirred by the same procedure as in the above measurement of the amount of charge was placed on a magnet roll having a diameter of 310 mm. Next, a counter electrode that was precisely weighed was set, a bias voltage of 1 kV was applied to the polarity opposite to the toner polarity, and the magnet roll was rotated at 1000 rpm for 1 minute. Then, the counter electrode was precisely weighed again and the difference from the initial value was taken to calculate the weight of the separated toner attached to the counter electrode, that is, the toner with poor charging. In this way, the ratio of the weight of the poorly charged toner to the total weight of the toner used for the measurement was defined as the amount of the poorly charged toner.

(5) Evaluation of Cleaning Property The developer prepared in the same manner as the measurement of the charge amount was put in a developing device of a commercially available electrophotographic copying machine EP570Z (manufactured by Minolta Camera Co., Ltd.), and 500 sheets were printed. I went to work. At this time, by visually observing whether or not the toner on the photosensitive drum that has passed through the cleaning blade is left unworn,
The cleaning property was evaluated according to the following criteria. ◯: There is no unwiped portion and the cleaning property is good. Δ: A part of the unwiping is left, but there is no problem in practical use. X: Unwiping occurs and is not practical.

The results of the above measurements are summarized in Table 1.

[0083]

[Table 1] As shown in Table 1, all of the examples have a sufficient charge amount, the occurrence of poorly charged toner is extremely small, and the cleaning property is good. On the other hand, in each of the comparative examples, a large amount of poorly charged toner was generated, and the cleaning property was also problematic in practice. In addition, all of the comparative examples had a broader particle size distribution and a larger amount of fine powder than the examples.

The toner of the example has a sharper particle size distribution than that of the comparative example, because the calcium phosphate salt disperses the droplets in a sufficiently stable state, so that the fine droplets and the aggregation of the calcium phosphate salt itself are caused. It is considered that this is because it becomes difficult to generate and the various conditions for dispersion, that is, the permissible range of the stirring conditions and the O / W ratio are widened, which makes it easy to obtain a sharp particle size distribution.

[0085]

As described above, in the present invention, a coloring resin solution obtained by dissolving and / or dispersing a binder resin and a coloring agent in a water-insoluble organic solvent is used as a calcium phosphate salt as a dispersion stabilizer. Since it is emulsified and dispersed in an aqueous dispersion containing, the occurrence of poorly charged toner is small, and the charge control agent has good controllability of the charge amount, and a desired sufficient charge amount can be easily provided. Furthermore, it is possible to provide a toner for developing an electrostatic latent image, which has good cleaning properties and has a sharp particle size distribution.

[Brief description of drawings]

FIG. 1 is a view showing an electron micrograph of a toner of Example 1 at a magnification of 10,000 times.

FIG. 2 is a view showing a 5,000 times electron micrograph of the toner of Comparative Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsutoshi Nakamura 2-3-13 Azuchi-cho, Chuo-ku, Osaka, Osaka International Building Minolta Camera Co., Ltd. (72) Yukio Tanigami 2-chome, Azuchi-cho, Chuo-ku, Osaka 3-13 No. 13 Osaka International Building Minolta Camera Co., Ltd.

Claims (2)

[Claims] 1. A coloring resin solution is prepared by dissolving and / or dispersing at least a binder resin and a coloring agent in a non-water-soluble organic solvent, and the coloring resin solution is contained in an aqueous dispersion containing calcium phosphate as a dispersion stabilizer. After emulsifying and dispersing in
A toner for developing an electrostatic latent image, which is produced by removing a non-water-soluble organic solvent and further removing a calcium phosphate salt. 2. A step of dissolving and / or dispersing at least a binder resin and a colorant in a non-water-soluble organic solvent to obtain a colored resin solution, and an aqueous solution containing the colored resin solution as a dispersion stabilizer containing calcium phosphate salt. A step of emulsifying and dispersing in a dispersion liquid to form an O / W type emulsion;
Production of a toner for developing an electrostatic latent image, comprising: a step of removing a water-insoluble organic solvent from a W-type emulsion to obtain resin fine particles; and a step of removing a calcium phosphate salt contained in the resin fine particles. Method.