JP3007450B2 - Method for producing toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner for developing an electrostatic image, and more particularly to a method for producing a toner for developing an electrostatic image having excellent moisture resistance, small particle size and sharp particle size distribution. .

[0002]

2. Description of the Related Art Conventionally, as a method for producing a toner used for developing an electrostatic charge image, a colorant and other additives are melt-mixed and dispersed uniformly in a thermoplastic resin, and then the mixture is pulverized and classified. And a suspension polymerization method in which a polymerizable monomer, a polymerization initiator, and a colorant are suspended in an aqueous medium and polymerized to a toner size. In particular, in the suspension polymerization method, it is possible to obtain a toner having a spherical shape, excellent fluidity, a uniform particle size and a sharp particle size distribution.

[0003]

In the melt-kneading method, it is difficult to obtain a toner having a uniform particle size and a sharp particle size distribution, and the productivity is low due to long steps. on the other hand,
In the suspension polymerization method, since a relatively large amount of the dispersion stabilizer is used, the dispersion stabilizer remains in the obtained toner, and the moisture resistance is low. Further, since the toner is suspended at room temperature, a long time is required for suspension to obtain a toner having a desired particle size and a sharp particle size distribution, and the productivity is low. In order to shorten the suspension time, a method of suspending at a high temperature (60 to 70 ° C.) has also been proposed (for example, JP-A-59-123853, JP-A-59-152446, JP-A-60-152446). -57856
However, in this method, since polymerization proceeds during suspension, it is difficult to control the particle size and sharpen the particle size distribution of the obtained toner, especially in a high old-up process. Have difficulty.

The object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a uniform particle size, a sharp particle size distribution, excellent moisture resistance, and a short suspension time even in a high hold-up. An object of the present invention is to provide a method for producing a toner for developing an electrostatic charge image having good productivity.

[0005]

According to the present invention, there is provided a method for producing a toner for developing an electrostatic image, comprising: dispersing a polymerizable monomer, a colorant and a dispersion stabilizer in a dispersion solvent at room temperature; A step of heating and suspending at a temperature intermediate to the temperature at which polymerization of the polymerizable monomer starts, and a step of heating the resulting suspension to polymerize the polymerizable monomer. The above object can be achieved.

Next, the present invention will be described in detail.

To produce the toner for developing an electrostatic image of the present invention, first, a polymerizable monomer and a colorant dispersion stabilizer are dispersed in a dispersion solvent at room temperature.

As the polymerizable monomer, for example, the following can be used. Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,
p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p- n-hexylstyrene, pn-octylstyrene, pn-
Styrene such as nonylstyrene and pn-dodecylstyrene and derivatives thereof: ethylene, propylene, butylene,
Isobutylene nadonoethylenically unsaturated monoolefins:
Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride: vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate:
Methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethyl methacrylate Α-methylene aliphatic monocarboxylic esters such as aminoethyl and diethylaminoethyl methacrylate: methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, acrylic acid Acrylic esters such as dodecyl, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate: vinyl methyl ether,
Vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether: vinyl methyl ketone, vinyl hexyl ketone, vinyl ketones such as methyl isopropenyl ketone: N-vinyl pyrrole, N-vinyl carbazole,
N- such as N-vinylindole and N-vinylpyrrolidone
Vinyl compounds: vinyl naphthalenes: acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, etc .: One or more of these polymerizable monomers can be used.

The amount of the polymerizable monomer used is preferably at least 90% by weight of the whole mixture.

As the colorant, conventionally known pigments or dyes can be used. Examples of the dye include C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modant red, C.I. I. Direct Blue 1, C.I. I. Acid Blue 1, C.I.
I. Acid Blue 2, C.I. I. Acid blue 9,
C. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic blue, C.I. I. Modant Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Basic Green 6 and the like. Examples of the pigment include, for example, graphite, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hansa yellow, permanent yellow NCG, tartan rake, red-mouthed graphite, molybdenum orange, and permanent orange GT.
R, pyrazolone orange, benzidine orange G, cadmium red, permanent red 4R, watching red calcium salt, eosoroke, brilliant carmine 3B, manganese purple, fast bio red B, methyl bio red lake, navy blue, cobalt blue, alkaline blue lake, Victoria Blue Lake, Phthalocyanine Blue, First Sky Blue, Indanthrene Blue BC, Chrome Green, Chromium Oxide, Pigment Green B, Malachite Green Lake, Final Yellow Green G, Carbon Black, Acetylene Black, Lamp Black and the like.

The amount of the colorant is preferably 1 to 20 parts by weight based on the amount of the polymerizable monomer.

Examples of the dispersion stabilizer include: organic dispersants: gelatin, denbum, water-soluble cellulose derivatives such as carboxymethyl cellulose, polyvinyl alcohol, and anionic, nonionic, cationic or amphoteric surfactants. Inorganic dispersant: Insoluble inorganic fine particles, for example,
Various clays such as calcium carbonate, magnesium phosphate, magnesium carbonate, silica, alumina, talc and bentonite, and diatomaceous earth are exemplified. These can be used alone or in combination of two or more.

The use amount of the above-mentioned dispersion stabilizer is preferably 0.1 to 10% by weight based on the use amount of the dispersion solvent. When the amount is less than 0.1% by weight, the dispersion is insufficiently dispersed. On the other hand, when the amount exceeds 10% by weight, it remains on the surface of the obtained toner, and the moisture resistance is reduced.

As the dispersion solvent, an aqueous dispersion solvent is used, and for example, water, alcohol, or a mixture thereof is preferably used.

If necessary, a polymerization initiator, a cross-linking agent, a charge control agent, a fluidity modifier and other additives may be added to the dispersion solvent.

As the above-mentioned polymerization initiator, conventionally known ones can be used. For example, azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide and the like can be used. it can.

The amount of the polymerization initiator used is preferably 0.1 to 10% by weight based on the amount of the polymerizable monomer used.

The above-mentioned polymerization initiator may be added to the suspension in the next suspension step.

As the crosslinking agent, for example, the following compounds can be used. Divinylbenzene, divinylnaphthalene, divinylether, divinylsulfone,
Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl Glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane,
2,2-bis (4-acryloxydiethoxyphenyl)
Propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, dibromoneopentyl glycol dimethacrylate, diallyl phthalate, and the like.

The amount of the crosslinking agent used is preferably 0.5 to 1.5% by weight based on the amount of the polymerizable monomer used. When the amount of the cross-linking agent is less than 0.5% by weight, properties such as blocking resistance and durability required as a toner are deteriorated. The offset phenomenon of sticking to the surface and transferring to the next paper cannot be prevented. On the other hand, if the amount of the cross-linking agent exceeds 1.5% by weight, the solubility decreases and the fixability deteriorates.

As the charge control agent, for example, metal-containing dyes, nigrosine and the like can be used.

As the fluidity modifier, for example, colloidal silica, fatty acid metal salt and the like can be used.

In order to use the toner as a magnetic toner, a magnetic powder may be contained. As such a magnetic powder, for example, a powder of a ferromagnetic metal such as iron, cobalt, and nickel, or a powder of an alloy or a compound such as magnetite, hematite, or ferrite is used.

The charge control agent, the fluidity modifier, and the magnetic powder may be mixed (externally added) with the obtained toner.

The method for dispersing the above-mentioned polymerizable monomer, colorant and dispersion stabilizer in a dispersion solvent can be carried out using a conventional stirrer, homomixer, homogenizer or the like.

The above dispersion is preferably performed at room temperature for 10 to 60 minutes.

By this dispersion step, 5 to 20
A μm oil droplet is formed.

Next, the dispersion is heated and suspended to an intermediate temperature between room temperature and the temperature at which the polymerization of the used polymerizable monomer starts. Here, the temperature at which the polymerization of the polymerizable monomer starts refers to a temperature at which the polymerizable monomer substantially starts the polymerization in the presence of the polymerization initiator. A preferable heating temperature is 20 to 50 ° C. The heating temperature need not be constant as long as it is within the above range.

The heating time in the above suspension step varies depending on the type and amount of the polymerizable monomer used, but the time until suspension is completed, that is, droplets having a desired particle size are formed. Until about 10 to 60 minutes. The heating method in the suspension step is usually performed in a hot water bath or a homomixer equipped with a constant temperature jacket.

In this suspension step, the viscosity of the oil droplets and the dispersion solvent present in the dispersion is reduced by heating the dispersion, and the viscosity of the oil droplets is lower than that of the dispersion solvent. Because of the large size, the difference in viscosity between the two is large.
Accordingly, the shearing efficiency due to mechanical stirring is improved, and the oil droplets formed in the above-described dispersion step have a small diameter and a sharp particle size distribution in a short time.

If the heating temperature in the suspension step is lower than room temperature, the viscosity or interfacial tension of the oil droplets increases, so that it takes a long time to form oil droplets of a desired particle size, especially in a high hold-up. I need. On the other hand, when the heating temperature exceeds the temperature at which the polymerization of the polymerizable monomer starts,
The formation of the oil droplets is not changed sufficiently, and the particle diameter of the obtained toner is large because the polymerization reaction occurs.

As for the viscosity of the dispersion in the suspension step, it is preferable to use a dispersion having the following viscosity at 30 ° C. or higher.

Η ₁ (aqueous phase) = 5.8462−0.1530T−0.0011T ² −0.0001T ³ η ₂ (oil phase) = 18.2868−0.9038T −0.0531T ² −0.0019T ³ In such a dispersion, the viscosity of the aqueous phase is ₁ cp ≦ η ₁ ≦ 5 cp and the viscosity of the oil phase is 5 cp in the above-mentioned heating temperature range.
≦ η ₂ ≦ 15 cp, whereby droplets having a small diameter and a sharp particle size distribution can be formed.

In the suspension step, the hold-up of the dispersion is preferably 10 to 50% by weight. When the hold-up is less than 10% by weight, the productivity is poor. On the other hand, when the hold-up exceeds 50% by weight, the viscosity of the dispersion becomes large, so that it is impossible to form a small-diameter oil droplet having a sharp particle size distribution.

The particle size of the oil droplets formed by the above suspension step is preferably 5 to 20 μm, and the particle size distribution is preferably such that D75 / D25 is 1 to 2.

Next, the suspension is polymerized by raising the temperature to a temperature at which the polymerization of the polymerizable monomer starts. Thereby, a toner can be prepared.

The polymerization temperature in the polymerization step is preferably 20 to 30 ° C. higher than the temperature at which the polymerization of the polymerizable monomer starts.

The polymerization time in the above polymerization step is 1-2.
It is preferably 0 hours.

After the completion of the polymerization reaction, the above suspension is filtered, washed with water and dried to obtain a toner.

The particle size of the obtained toner is preferably 5 to 5.
It is preferably 20 μm, particularly preferably 8 to 12 μm, and the particle size distribution is preferably such that D75 / D25 is 1-2.

[0041]

The suspension of the dispersion is performed at an intermediate temperature between room temperature and the temperature at which the polymerization of the polymerizable monomer starts, thereby suppressing an increase in the viscosity of oil droplets due to the polymerization of the polymerizable monomer. . Further, the viscosity of the oil droplets and the dispersion solvent present in the dispersion is reduced by heating, but the viscosity difference between the oil droplets and the dispersion solvent is large because the decrease in the viscosity of the oil droplets is greater than that of the dispersion solvent. Accordingly, the shearing efficiency due to mechanical stirring is improved, and the oil droplets formed in the above-described dispersion step have a small diameter and a sharp particle size distribution in a short time. In this state, by further heating and conducting a polymerization reaction, a toner having a small diameter and a sharp particle size distribution can be obtained. Accordingly, a toner having a small diameter and a sharp particle size distribution can be obtained even in a high hold-up, so that productivity is improved. In addition, since the interfacial tension of the oil phase is reduced by heating, the amount of the dispersion stabilizer used can be reduced, and the moisture resistance of the toner can be improved.

[0042]

Next, the present invention will be described with reference to examples and comparative examples.

Example 1 75 parts by weight of styrene 25 parts by weight of 2-ethylhexoxy methacrylate 0.2 parts by weight of divinylbenzene 5 parts by weight of carbon black 2.5 parts by weight of ADVN 0.3 part by weight of AIBN The above components were held up. To 16.4% by weight in Ca ₂ (PO ₄ ) ₃ and 100 ° C. for 10 minutes at 5 ° C., 25 ° C. and 70 ° C. using a homomixer.
Suspended at 00 rpm. Thereafter, the temperature of the suspension was raised to carry out a polymerization reaction at 80 ° C. for 8 hours, followed by filtration, washing with water and drying to obtain a toner for developing an electrostatic image. FIG. 1 shows the relationship between the volume distribution of the obtained toner particles and the cumulative% of the distribution.

Example 2 80 parts by weight of styrene 20 parts by weight of 2-ethylhexoxy methacrylate 0.2 parts by weight of divinylbenzene 5 parts by weight of carbon black 2.5 parts by weight of ADVN 0.3 part by weight of AIBN Each of the above components was held up. To 24.6% by weight in 1% by weight of Ca ₂ (PO ₄ ) ₃ and, using a homomixer, at 50 ° C. for 3 minutes, 5 minutes, 7 minutes,
For 15 minutes at 10,000 rpm. Thereafter, the temperature of the suspension was raised, and a polymerization reaction was carried out at 80 ° C. for 8 hours, followed by filtration, washing with water, and drying to obtain a toner for developing an electrostatic image. FIG. 2 shows the relationship between the volume distribution of the obtained toner particles and the cumulative% of the distribution.

1 and 2, the suspension time is long, and the suspension temperature is set at an intermediate temperature between room temperature and the temperature at which the polymerization of the polymerizable monomer starts, so that the particle size distribution is small and the particle size distribution is sharp. Toner can be obtained.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the dispersion was carried out at 15 ° C. for 10 minutes.
A toner for developing an electrostatic image was obtained in the same manner as in Example 1 except that the polymerization reaction was carried out at 0 ° C. for 8 hours.

The particle size and particle size distribution of the electrostatic image developing toner obtained by suspending the toner at 25 ° C. for 10 minutes in Example 1 and the electrostatic image developing toner obtained in Comparative Example 1 are described. An image was formed with a developer using a toner for developing a charge image.

In the toner for developing an electrostatic charge image obtained by suspending at 25 ° C. for 10 minutes in Example 1, D50 was 9.5 μm,
D75 / D25 was 1.2, the particle size was small, the particle size distribution was sharp, and good images were obtained. However, in the toner for developing an electrostatic image obtained in Comparative Example 1, D
50 was 10.1 μm, D75 / D25 was 2.2, and the particle size distribution was broad. In addition, fog occurred in the obtained image.

[0049]

As is apparent from the above description, according to the method of the present invention for producing a toner for developing an electrostatic image, even at a high hold-up, the particles have a uniform particle size, a sharp particle size distribution, and a high moisture resistance. It is possible to provide a toner which is excellent in susceptibility and has a short suspension time and good productivity.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the volume distribution of toner particles obtained in Example 1 and the accumulation of the distribution.

FIG. 2 is a graph showing the relationship between the volume distribution of toner particles obtained in Example 2 and the accumulation of the distribution.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (1)

(57) [Claims] In a method for producing a toner for developing an electrostatic image by a suspension polymerization method, a dispersion in which a polymerizable monomer, a colorant and a dispersion stabilizer are dispersed in a dispersion solvent is treated at room temperature with the polymerizable liquid. An electrostatic charge comprising a step of heating and suspending at a temperature intermediate to the temperature at which polymerization of the monomer starts, and a step of heating the resulting suspension to polymerize the polymerizable monomer. A method for producing an image developing toner.