JPS62299862A - Production of toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To efficiently obtain a toner which permits easy control of an average grain size and has an extremely narrow grain size distribution by incorporating a dispersion stage consisting in pressurizing a liquid dispersion medium contg. a dispersion stabilizer to >=10kg/cm<2>, then passing the same through a narrow passage to the titled method. CONSTITUTION:The liquid dispersion medium 3 consisting of the fine powder dispersion stabilizer 1 and a dispersion medium 2 is pressurized by a pressurizing means to a prescribed pressure of >=10kg/cm<2> and is supplied to a high-pressure part 4. The pressurized liquid dispersion medium 3 is discharged from a space 7 between a valve seat 5 and valve 6 constituting a valve mechanism toward an impact ring 8 which is a collision member at a high velocity by a pressure difference between a high-pressure part 4 and a low-pressure part 9. As a result, flocks 1a of the fine powder dispersion stabilizer which fail to act effectively by forming the flocculated lumps are broken and dispersed to form nearly the ultrafine particles 1b. The sharp grain size distribution of the dispersion stabilizer 1 in the liquid dispersion medium 3 is thus formed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention 1. Publication I The present invention provides a toner for developing electrostatic images in image forming methods such as electrophotography, electrostatic photography, and electrostatic printing. More specifically, the present invention relates to a method for producing a toner for developing electrostatic images using an improved suspension polymerization method that includes a granulation step for efficiently forming particles with a sharp particle size distribution.

11. Conventional methods for developing electrostatic images formed on a recording medium in electrophotography, electrostatic recording, electrostatic printing, etc. are broadly divided into methods using various pigments and dyes in an insulating liquid. a cascade method using fine particles called toner, which is made by dispersing a coloring agent such as carbon black in a natural or synthetic polymer or wax, and a bristle brush method. There are so-called dry developing methods such as a magnetic brush method, an impression printing method, and a powder cloud method.

The liquid developing method has problems such as the processing of the developer used therein is troublesome and a unique unpleasant odor is generated during and after the development and fixing process, so the dry developing method using the toner is mainly used. It is put into practical use.

The toner for developing electrostatic images used in the dry development method is usually
For example, a binder made of a vinyl polymer such as polystyrene or polyacrylic acid ester, an epoxy polymer, a petroleum polymer, an ester condensate, etc., and a coloring agent such as carbon black are mixed, melted and kneaded, It is manufactured by cooling, pulverizing, and further classifying the toner particles to have a particle size of 1 to 50 gta. The toner formed in this manner is required to satisfy certain characteristics such as storage stability, durability, moisture resistance, electrostatic properties, fluidity, fixability, and imageability.

Forming toner by the above-mentioned manufacturing method called the so-called pulverization method has many advantages, and it is said that most of the dry toners currently on the market are manufactured by this pulverization method.

However, this manufacturing method has many problems. In other words, in the pulverization method, the wind-powered convex type pulverizer that is used as the main part of the pulverization process uses a large amount of compressed air, requiring a large amount of equipment cost, and also requires a large amount of electricity during operation. Since a large amount of toner is consumed, these costs account for much of the toner processing cost.In particular, in recent years, toner with small particle size is required to improve the quality of copied images.
With the current pulverization method, which consumes a large amount of energy during pulverization, it is difficult to efficiently generate toner with a small particle size, resulting in a considerable increase in cost. Furthermore, when toner with a small particle size is produced by a pulverization method, the particle size distribution of the pulverized product tends to be broad and a large amount of unnecessary ultrafine powder is generated, and the generated ultrafine powder is extremely difficult to remove by classification. be.

Furthermore, in order to be effectively pulverized in this pulverization method, the toner material must have appropriate brittleness, and the selection of raw materials is limited to those having such brittleness. Additionally, when softer materials are used to improve toner fixation, the heat and pressure generated during pulverization tend to cause fusion in the equipment used in various processes. In such a case, it becomes impossible to operate the toner manufacturing apparatus continuously for a long time.

In order to overcome these problems, a toner production method using a suspension polymerization method that does not involve dry pulverization has been proposed. This method is an excellent method that eliminates the above-mentioned disadvantages by omitting the melt-kneading process and the grinding process.However, in dry toner production using the conventional suspension polymerization method, the following points are New problems are arising.

That is, firstly, in the production of toner by the usual suspension polymerization method, in the granulation step, a liquid monomer composition containing a polymerizable monomer and a colorant is granulated in a liquid dispersion medium.
There is a problem in that it is very difficult to efficiently control the monomer composition particles to a desired particle size. Secondly, in the current suspension polymerization method, the particle size distribution of the produced polymer particles is wide, and polymer particles with large particle diameters are produced, so the weight proportion of particles in the appropriate particle size range is small. In the above-mentioned pulverization method, which has poor productivity, the particles removed in the classification operation to obtain an appropriate particle size range can be reused after being remixed with the raw material and then passed through the cross-mixing process. In this suspension polymerization method, it is currently difficult to reuse the resulting polymer particles of poor particle size.

In the suspension polymerization method, in order to solve the problem of particle size distribution as described above, it is necessary to granulate monomer composition particles with a particle size that can finally produce a toner with a desired particle size distribution. It is necessary to produce stable yields in the process, but
In this respect, conventional suspension polymerization methods still have many problems to be solved.

One of the most important of these issues is the issue of dispersion stabilizers to obtain proper particle size distribution. In other words, in the suspension polymerization method, the main steps are carried out in a liquid medium (
(Usually water is used as a medium), but in the granulation process,
Dispersion stabilizers are used to form and stabilize monomer composition particles. Such dispersion stabilizers usually include BaSO4, CaSO4, CaC0, poorly water-soluble inorganic fine powder such as silica, polyvinyl alcohol,
Water-soluble polymers such as gelatin, water-soluble surfactants, etc. are used singly or in combination.

Due to their role, these dispersion stabilizers have strong wood-philic properties, and if they remain in the produced toner, the developing ability and transfer efficiency will decrease mainly due to a decrease in the chargeability of the toner. In particular, under conditions of high humidity, image quality such as a decrease in copy density, a decrease in resolution, and blurring and flickering occur. Therefore, from this point of view, it is required to reduce the amount of dispersion stabilizer used as much as possible, but at the same time, use a small amount of dispersion stabilizer to reduce the particle size of the monomer composition and improve the particle size distribution. We must solve the problem of sharpening the image.

In order to solve this problem, we have improved the material of the dispersion stabilizer itself,
Efforts have been made to reduce the amount used, but in the conventional granulation process, reducing the amount of dispersion stabilizer results in the monomer composition particles becoming coarser and having a wider particle size distribution, which can be used in the subsequent polymerization process. Since secondary aggregation of monomer composition particles frequently occurs, it becomes difficult to obtain a polymer with an appropriate particle size. Especially when trying to obtain toner with small particle size, these two
Subaggregation becomes an extremely serious problem.

An object of the present invention is to produce a toner that can easily control the average particle size and efficiently produce a toner with an extremely narrow particle size distribution in the production of a toner for electrostatic image development using a suspension polymerization method. It is about providing law.

Another object of the present invention is to provide a method for efficiently producing dry toner with small particle size.

Still another object of the present invention is to provide a method for producing a toner having a homogeneous and sharp particle size distribution while reducing the amount of dispersion stabilizer used in toner production using a suspension polymerization method. .

Still another object of the present invention is to provide a method for producing a toner having good powder characteristics and good development, transfer, fixing, and cleaning properties.

Still another object of the present invention is to provide a method for producing toner at low cost and with good productivity.

As a result of intensive research, the inventors have found that under actual granulation conditions (particularly in the presence of a dispersion medium consisting of water, etc.) in the granulation process when obtaining toner by suspension polymerization, It has been found that the particle size distribution of the dispersion stabilizer itself (how sharp the particle size distribution is) is an extremely important issue.

The present inventors conducted further research based on the above findings, and found that instead of adding the fine powder dispersion stabilizer directly to the mixed system (dispersion) to be granulated, (before adding the monomer composition) ) A liquid dispersion medium containing a dispersion stabilizer was heated to 10K.
By introducing a dispersion process in which the dispersion stabilizer is pressurized to g/cm2 or more and then passed through a narrow passage, it is possible to achieve a sharp particle size distribution of the dispersion stabilizer itself in advance in the liquid dispersion medium. We have found that it is extremely effective in achieving our goals.

The toner manufacturing method of the present invention is based on such knowledge, and more specifically, after pressurizing a liquid dispersion medium containing a fine powder dispersion stabilizer to 1 OK g/cm2 or more, A dispersion step of dispersing the dispersion stabilizer by passing through a passage, and a monomer containing at least a polymerizable monomer and a colorant in the liquid dispersion medium in which the dispersion stabilizer is dispersed in the dispersion step. A product characterized by having at least a granulation step of dispersing and suspending the composition and granulating it, and a polymerization step of suspension polymerizing the granulated monomer composition to form toner particles. It is.

The reason why the above-mentioned effects can be obtained in the present invention is as follows.
Although it is not necessarily clear, it is estimated as follows.

In the dispersion process of the present invention, the liquid dispersion medium containing the fine powder dispersion stabilizer is pressurized to 10 kg/cm2 or more, passes through a narrow passage, and is discharged to a lower pressure area, resulting in intense turbulence. Fluid friction, sudden decreases in pressure, shear forces, or impacts efficiently convert pressure energy into distributed energy.

Due to the high dispersion energy generated in this way, the agglomerates of the fine powder dispersion stabilizer that had formed strong agglomerates (secondary particles) and were not working effectively are destroyed, and the particles become closer to ultrafine particles. It is efficiently dispersed in the liquid dispersion medium, and a sharp particle size distribution of the fine powder dispersion stabilizer itself in the liquid dispersion medium is realized.

As a result, in the granulation process, the dispersion stabilizing effect (by the coarse powder dispersion stabilizer) on monomer composition particles with a desired particle size is suppressed to a low level, while the monomer composition with a desired particle size Since the dispersion stabilizing effect on the Qt-1 component particles is significantly enhanced, the number of monomer composition particles having the above-mentioned predetermined particle size increases significantly, resulting in an extremely sharp particle size distribution of the Qt-1 component particles. Not only that, but also the dispersion stabilizing ability of the dispersion stabilizer as a whole is improved, so it is estimated that the amount of dispersion stabilizer used can be reduced compared to the conventional method.

The present invention will be explained in more detail below. In the following description, "1 part" and "1%" expressing quantitative ratios are based on weight unless otherwise specified.

゛・1 In the production method of the present invention, 10 kg of liquid dispersion medium containing a fine powder dispersion stabilizer such as fine silica powder is used.
/cm2 or more, the fine powder dispersion stabilizer is dispersed by passing through a narrow passage (dispersion step), and then a polymerizable monomer such as styrene and a colorant such as carbon black are added. , (polymerization initiator, etc. if necessary) is put into a liquid dispersion medium in which a dispersion stabilizer has been previously dispersed according to the above-mentioned dispersion process, and the monomer composition containing a high shear force stirring device or a piston is added. The -F vehicle mass composition is dispersed, suspended, and granulated using a means such as a type high-pressure homogenizer (granulation step). As a result, in the granulation process, the monomer composition has a sharp particle size distribution on the particle surface,
In addition, the presence of a fine powder dispersion stabilizer with improved dispersion stabilizing ability selectively stabilizes the monomer composition particles with a desired particle size, resulting in a sharp particle size distribution of the monomer composition particles. Realized.

The dispersion means used in the dispersion stabilizer dispersion step in the present invention includes a dispersion device having a pressure mechanism for pressurizing the processing liquid and a valve mechanism for discharging or spouting the pressurized processing liquid. However, using a device with an impact mechanism for colliding the discharged processing liquid (in addition to these mechanisms) can further improve the efficiency of converting pressure energy into dispersion energy and stabilize the dispersion. It is further preferred in that it enables more efficient dispersion of the agent.

Such a dispersion device is generally used as a homogenizer (high-pressure homogenizer) for milk, inorganic powder, etc., and for example, GAULIN C.
An example of such a device is a piston-type high-pressure homogenizer manufactured by 0RPORATION.

Hereinafter, the present invention will be described in the case where a piston-type high-pressure homogenizer having a pressure mechanism, a valve mechanism, and an impact mechanism, as shown in a schematic side sectional view in FIG. 1, is used as a means for dispersing a dispersion stabilizer. The aspect will be explained.

Referring to FIG. 1, a liquid dispersion medium 3 consisting of a fine powder dispersion stabilizer l and a dispersion medium 2 is heated by a pressurizing means (not shown).
It is pressurized to a predetermined pressure of OK g/cm 2 or more and supplied to the high pressure section 4. In such a homogenizer,
As the pressurizing means, a positive displacement plunger pump is preferably used, which has a high quantitative property and can arbitrarily adjust the pressure.

The pressurized liquid dispersion medium 3 is directed from the gap 7 between the valve seat 5 and the valve 6, which constitute the valve mechanism, toward the impact ring 8, which is the collision member, due to the pressure difference between the high pressure section 4 and the low pressure section 9. It is discharged at high speed and collides with the surface of the impact Φ ring 8.

As a result, the aggregates 1a of the fine powder dispersion stabilizer, which had formed aggregates and was not working effectively, were broken and dispersed.
A sharp particle size distribution of the dispersion stabilizer 1 in the liquid dispersion medium 3 is realized, which is closer to the ultrafine particles 1b.

In such a piston-type high-pressure homogenizer, the liquid dispersion medium 3 is pressurized to 10 kg/cm 2 or more before passing through the gap 7 in order to atomize the dispersion stabilizer 1. If the pressure is 10 kg/am2 or less, the pressure difference between the high pressure section 4 and the low pressure section 9 is small, so the speed at which the dispersion medium 3 is discharged is insufficient, and it is difficult to obtain an efficient dispersion effect of the dispersion stabilizer l. The dispersion medium 3 is preferably pressurized to 100 to 700 Kg/cm2, particularly 300 to 650 Kg/cm2, but as a result, the pressure difference between the high pressure section 4 and the low pressure section 9 is approximately 100 Kg10n' or more (or more). It is preferably about 300 to 650 kg/cm2), and the dispersion medium 3
is discharged S from the gap 7 at high speed and collides with the collision member 8.

When using the apparatus shown in Fig. 1, it is usually 1-1.
It is preferable to pass this dispersion device 000 times for dispersion, and the dispersion time is preferably about 2 to 60 minutes.

The liquid temperature during the dispersion step may be either room temperature or higher temperature, but high temperature is generally preferred. It is preferable to set this liquid temperature to the temperature during polymerization from the viewpoint of improving the efficiency of the process.

In the manufacturing method of the present invention, toner particles are manufactured through a dispersion process, a granulation process, and a suspension polymerization process. The toner particles may be manufactured by passing through the steps continuously, or as shown in FIG. , a granulation process, and a polymerization process to produce toner particles.

Furthermore, as shown in the process diagram of FIG. 4, the dispersion process may be repeated n times (usually n=2 to 1.000) in series.

In addition, in the dispersion process using a piston-type high-pressure homogenizer, a commonly known emulsifying and dispersing device such as a high-shear stirring device such as a TK homomixer or an ultrasonic dispersion device may be used in connection with this high-pressure homogenizing device. is also valid.

The liquid dispersion medium in which the dispersion stabilizer has been well dispersed through the above-mentioned dispersion process is subjected to the primary granulation process (or (preliminary granulation step).

It is also effective to provide a preliminary granulation step of the monomer composition after this dispersion step and before the granulation step.

Here, the pre-granulation step refers to a monomer composition containing a polymerizable monomer such as styrene, a colorant such as carbon black (polymerization initiator, etc. if necessary), and a dispersion stabilizer present. This is a step of pre-granulating the particles of the monomer composition pre-granulated in this way using a dispersion means such as a high shear force stirring mixer in a liquid dispersion medium. Due to the presence of the dispersion stabilizer with improved dispersion stabilizing ability, the particle state is maintained for a while even after the stirring by the stirring means is stopped.

Next, the granulation process will be described.

Granulation of the monomer composition in a liquid dispersion medium can be carried out, for example, by TK
This can be carried out for 1 to 60 minutes using a high shear force mixer such as a type homo mixer or an ultra homo mixer, or an ultrasonic dispersion device.The monomer composition is already polymerized at this stage. It may contain an initiator, and
After the granulation step is completed, a polymerization initiator may be added to a liquid medium containing monomer composition particles adjusted to a polymerization temperature, and the mixture may be subjected to a suspension polymerization reaction.

Furthermore, it is preferable to repeat the granulation process by circulating the dispersion liquid continuously or intermittently in the granulation process, from the viewpoint of sharpening the particle size distribution. Furthermore, in the granulation process,
Granulation devices are connected in series and the granulation process is performed n times (usually n=
1 to 1000)<May be repeated.

In the present invention, the finely divided monomer composition particles are protected by a fine powder dispersion stabilizer having improved dispersion stabilizing ability. Therefore, if a sharp particle size distribution cannot be obtained by passing through the granulation process twice,
Even if the granulation process is carried out multiple times, the possibility that the monomer composition particles having the desired particle size will be further divided is extremely small compared to conventional granulation methods.

The liquid temperature during the granulation step in the present invention is such that the monomer composition has a viscosity of 1 to 1 million cps, preferably 100,000 to 100,000 cps.
When the temperature is adjusted to s, the particle size of the monomer composition particles can be adjusted to 1 to 20 gta, and finally a developing toner having a volume average particle size of 1 to 20 pL11 can be produced. As the dispersion medium constituting the liquid dispersion medium, water or an aqueous medium containing water as a main component is usually used.
The temperature is preferably adjusted to 40 to 70°C.

In the L-dispersion liquid, it is preferable that the liquid dispersion medium is present in an amount of 200 to 1000 parts with respect to 100 parts of the monomer composition. The dispersion stabilizer is preferably used in an amount of 1 to 20 parts, more preferably 2 to 15 parts, based on 100 parts of the monomer composition.

In the granulation process of the present invention, by combining with the dispersion process of the dispersion stabilizer itself as described above, approximately 1 to 20 I
Approximately 90% to 10% of the case where monomer composition particles having the same average particle size having a volume average particle size of L11 are produced without going through the above dispersion step (conventional method) With the use of a certain amount of dispersion stabilizer, it is possible to granulate it. Furthermore, in the present invention, the time required for the granulation process can be made shorter than before due to the improvement in the dispersion stabilizing ability of the dispersion stabilizer itself.

Before the monomer composition particles formed by the granulation step as detailed above are subjected to the next polymerization step, the monomer composition particles may be subjected to a classification treatment, if necessary.

This classification process can be performed, for example, using a wet classifier, but at this time, particles of the desired particle size generated during granulation are
After being separated from particles with non-standard particle sizes by a classifier, they are led to a polymerization process using a gentle stirring device set to conditions that prevent particles from coalescing or settling. It is offered.

On the other hand, the non-specified coarse particles separated by the classifier are returned to the granulation process, and then subjected to the granulation process to form particles of the desired particle size Y-, and then sequentially taken out in the same manner as above, and similarly subjected to the polymerization process. Serve.

As a result, coarse particles can be atomized as desired without being affected by the miniaturization of monomer composition particles having a desired particle size, making it possible to improve the yield in the granulation process. .

When performing such a classification process, it is preferable to use a so-called wet classifier that utilizes the difference in sedimentation speed of particles in a liquid.

Wet classifiers are classified into settling tank type, mechanical classifier type, hydraulic classifier type, hydrocyclone type, centrifugal classifier type, inertial force classifier type, etc. In the present invention, hydraulic classifier type, Hydrocyclone type, centrifugal classification type, and inertial force classifier type are preferably used.
In particular, hydrocyclone type, centrifugal classifier type, and inertial force classifier type are preferably used.

Next, the materials constituting the monomer composition will be explained.

The polymerizable composition used in the present invention is a monomer having a CH2=C group, and specifically includes the following monomers.

Namely, styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, P-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4
-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-te
rt-butylstyrene, Pn-hexylstyrene, p
-n-octylstyrene, p-n-nonylstyrene, p
- Styrene and its derivatives such as n-decylstyrene and p-n-dodecylstyrene; ethylenically unsaturated upper olefins such as ethylene, propylene, butylene and isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide,
Vinyl halides such as vinyl fluoride; vinyl acetate,
Vinyl esters such as vinyl propionate and vinyl benzoate; ethyl methacrylate, ethyl methacrylate,
Propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. α-methylene aliphatic monocarboxylic acid esters; methyl acrylate, ethyl acrylate,
Acrylic acid esters such as n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; Maleic acid, maleic acid/＼-phester; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl silketone, methyl isopropenyl ketone; N-vinylpyrrole, N -Vinylcal/(N-vinyl compounds such as sol, N-vinylindole, N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; etc., alone or in combination) Can be used in combination of more than one species.

Among the above seven monomers, it is preferable to use styrene or a styrene derivative alone or in combination with other monomers as a polymerizable monomer in order to improve the development characteristics and durability of the toner.

The monomer composition contains waxes such as paraffin wax, and releasable materials such as low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene, in order to improve fixing properties and anti-offset properties in hot pressure roller fixing. It is preferable to add a low softening point compound having . in this case.

The amount of the low softening point compound added is 1 to 300 parts per 100 parts of monopolymerizable monomer.

Examples of low softening point compounds include paraffin, wax, low molecular weight polyolefin, modified wax having an aromatic group,
Hydrocarbon compounds having an alicyclic group, natural waxes, long-chain carboxylic acids having a long-chain hydrocarbon chain having 12 or more carbon atoms (CHI (CH2)u or ('CH2) aliphatic carbon chain having 12 or more), and esters thereof. For example, different low softening point compounds may be mixed and used.

Examples of such low softening point compounds include paraffin wax (manufactured by Nippon Oil), paraffin wax (manufactured by Hiki Seiro), microwax (manufactured by Nippon Oil), microcrystalline wax (manufactured by 8ki Seiro), Hard paraffin wax (manufactured by Nippon Seiro), PE-130 (manufactured by Hoechst)
; Mitsui Hiwax ll0P, Mitsui Hiwax 220
P, Mitsui Hiwax 660P, Mitsui Hiwax 21
0F, Mitsui Hiwax 320P, Mitsui I\Iwax 410F, Mitsui Hiwax 420P, Ha(lz,'/
T-100X, HiLz, ”/T-200X, HiRaytsu T-300X, Vetrogin 80, Vetrogin 100
, Vetrogin 120. Tuck Ace A-1oo, Tuck Ace F-100, Tuck Ace B-60, modified wax JC-1141, modified wax JC-2130, modified wax JC-4020. Modified wax JC-1142
, modified wax JC-5020 (manufactured by Mitsui Petrochemicals)
; Examples include beeswax, carnauba wax, montan wax, etc.

Suspension polymerization may be carried out in the presence of the following crosslinking agent in the monomer composition in order to produce a crosslinked polymer. Alternatively, when cyclized rubber is not added, it is preferable to add a crosslinking agent.

Examples of the crosslinking agent include divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1.3-butylene glycol dimethacrylate, 1.6-hexane gelicold dimethacrylate, and neopentyl glycol dimethacrylate. methacrylate,
Dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis(4
-methacryloxyjethoxyphenyl)propane, 2.
2'-bis(4-acryloxyjethoxyphenyl)propane, trimethylolpropane trimethacrylate,
Common crosslinking agents such as trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate-I., dibromoneopentylglycol dimethacrylate, and diallyl phthalate can be used as appropriate.

If the amount of these crosslinking agents used is too large, the toner will be melted by heat, resulting in poor heat fixing properties or heat pressure fixing properties. Also, if the amount of crosslinking agent used is too small, properties such as blocking resistance and durability necessary for toner will deteriorate, and during hot roll fixing, some of the toner will not completely adhere to the paper and will adhere to the roller surface. , it becomes difficult to prevent the offset phenomenon of transfer to the next paper. Therefore, the amount of these crosslinking agents used is 0 to 100 parts of polymerizable monomer.
．． It is preferable to use 001 to 15 parts (more preferably 001 to 10 parts).

As the coloring agent contained in the monomer composition, conventionally known dyes or known pigments such as carbon black and grafted carbon black, which is obtained by coating the surface of carbon black with a resin, are used. It is possible. The coloring agent is used in an amount of 0.1 to 3 parts per 1too part of polymerizability.
0 copies used.

If necessary, a charge control agent and a fluidity modifier may be added (internally added) to the toner thus obtained. Charge control agent and fluidity modifier are mixed with toner particles (external addition)
It may also be used as

Examples of charge control agents include metal complexes of organic compounds having carboxy groups or nitrogen-containing groups, metal-containing dyes, and nigrosine. Examples of fluidity modifiers or cleaning aids for the surface of the latent image carrier (photoreceptor) include colloidal silica and fatty acid metal salts. Also, for the purpose of increasing the amount, calcium carbonate,
A filler such as finely divided silica may be incorporated into the toner in an amount of 0.5 to 20% by weight. Furthermore, in order to prevent agglomeration of toner particles and improve fluidity, a fluidity improver such as fine Teflon powder or zinc stearate powder may be added.

To produce a magnetic polymerized toner, magnetic particles may be added to the monomer composition, and in this case, the magnetic particles also serve as (all or part of) a colorant.

The magnetic particles that can be used in the production method of the present invention include substances that are magnetized when placed in a magnetic field, such as powders of ferromagnetic metals such as iron, cobalt, and nickel, or powders of ferromagnetic metals such as magnetite, hematite, and ferrite. Examples include powders of alloys and compounds. As the magnetic particles, magnetic fine particles having a particle size of 0.05 to 5 ILm, preferably 091 to 1ILm are used, but when producing a small particle size toner, magnetic particles with a particle size of 0.8ILm or less are used. Preferably, magnetic particles are used in an amount of 10 to 150 parts, more preferably 20 to 100 parts, based on ioo parts of the monomer composition.

Further, these magnetic fine particles may be treated with a surface treatment agent such as a silane coupling agent, a titanium strength/sampling agent, or an appropriate reactive resin. In this case, although it depends on the surface area of the magnetic fine particles or the density of hydroxyl groups present on the surface, the amount of surface treatment agent etc. to be treated is usually 10 parts or less (preferably 0.1 to 5 parts) per 100 parts of the magnetic fine particles. Sufficient dispersibility in the polymerizable monomer can be obtained, and the physical properties of the toner are not adversely affected. Furthermore, magnetic particles made lipophilic by the above treatment and untreated hydrophilic magnetic particles may be mixed and used.

Next, the polymerization initiator used for polymerizing the monomer composition made of the above-mentioned materials will be described.

According to the findings of the present inventors, when a water-soluble polymerization initiator is used, the moisture resistance of the polymerized toner that is produced decreases, and the development characteristics and blocking resistance at high temperature and high humidity deteriorate. In order to produce a polymerized toner with excellent environmental properties, it is preferable to use a substantially water-insoluble polymerization initiator.

Here, in the present invention, a substantially water-insoluble polymerization initiator has a solubility of 1 g or less per 100 g of water at room temperature, and preferably has a solubility of 0 g or less per 100 g of water.
．． 5g or less, particularly preferably 0.2 per 100g of water
It has a low solubility of less than g.

When the polymerization initiator has a solubility of 1 g or more per 100 g of water, it is not preferable because decomposition products of the polymerization initiator remaining on the surface of the polymerized toner particles after completion of polymerization reduce the moisture resistance of the polymerized toner.

Further, the polymerization initiator used in the present invention is preferably soluble in the polymerizable monomer, and the amount ranges normally used (for example, 1 to 10 parts of the polymerization initiator per 100 parts of the polymerizable monomer). ) preferably has solubility characteristics that allow it to dissolve well in the polymerizable monomer.

Examples of such polymerization initiators include 2,2'-7 zobis-(2,4-dimethylvaleronitrile), 2,2'-7 zobisisobutyronitrile, l.

Azo-based compounds such as 1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and other azobisisobutyronitrile (A I B N) Or diazo polymerization initiators; examples include peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorylbenzoyl peroxide, and lauroyl peroxide. .

In the production method of the present invention, the molecular weight and molecular weight distribution of the polymer are controlled. It is also preferable to use a mixture of two or more types of polymerization initiators for this purpose or for the purpose of adjusting the reaction time.

The amount of the polymerization initiator used is usually 0.1 to 20 parts, preferably 1 to 10 parts per 100 parts of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 part, each monomer It is difficult to uniformly disperse or apply a sufficient amount of the polymerization initiator to the composition particles, and on the other hand, if the amount of the polymerization initiator exceeds 20 parts,
As the molecular weight of the polymerization product decreases, the tendency for the polymerization reaction to occur non-uniformly increases.

In the present invention, the suspension polymerization reaction is usually carried out at a polymerization temperature of 50
The upper temperature limit is set in consideration of the decomposition rate of the polymerization initiator. If the set polymerization source level is too high, the polymerization initiator will be rapidly decomposed, which is not preferable.

After confirming that the monomer composition particles formed by the granulation process have a predetermined particle size, the liquid temperature (for example, 55 to 70 ° C.) of the dispersion medium such as an aqueous medium containing the particles is adjusted. The polymerization reaction is allowed to proceed.

Furthermore, an additive consisting of a polar polymer, a polar copolymer, a cyclized rubber, etc. having a polar group that is soluble in the polymerizable monomer is added to the monomer composition, and the polymerizable monomer is polymerized. Then, a polymerized toner having preferable characteristics can be obtained.

The polar polymer, polar copolymer or cyclized rubber may be used in an amount of 0.5 to 50 parts, more preferably 1 to 50 parts, based on 100 parts of the polymerizable monomer.
It is best to add 40 parts of the polar polymer, etc. If the amount of the polar polymer, etc. is less than 0.5 part, it will be difficult to form a sufficient quasi-capsule structure with the polymerizable monomer as described below. If it exceeds this amount, the amount of polymerizable monomer becomes insufficient and the properties as a polymerized toner tend to deteriorate.

A polymerizable monomer composition to which a polar polymer, a polar copolymer, or a cyclized rubber is added is added to the aqueous phase of an aqueous medium in which the polar polymer, etc. and an oppositely charged fine powder dispersion stabilizer are dispersed. It is preferred to suspend and polymerize. That is, the cationic or anionic polymer, cationic or anionic copolymer, or anionic cyclized rubber contained in the polymerizable monomer composition contains oppositely charged anions dispersed in the aqueous medium. The cationic or cationic fine powder dispersion stabilizer and the toner particle surface are electrostatically attracted to each other, and the fine powder dispersion stabilizer covers the particle surface, thereby preventing the particles from coalescing and stabilizing them. In addition, since the added polar polymer, polar copolymer, or cyclized rubber gathers on the surface layer of the particles that will become the toner, the polar polymer etc. forms a kind of shell-like form.
The obtained particles have a pseudo-capsule structure. The relatively high molecular weight polar polymer, polar copolymer or cyclized rubber gathered on the surface layer of the particles gives the toner particles excellent properties such as blocking resistance, developability, charge controllability, and abrasion resistance. Grant.

Polar polymers that can be used in the present invention (hereinafter used to include polar copolymers and cyclized rubber) -
Examples of parts are shown below. It should be noted that polar polymers having a weight average molecular weight of 5,000 to 500,000 as measured by GPC are preferably used because they dissolve well in the polymerizable single polymer and have durability.

(1) Examples of cationic polymers include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl acrylate, copolymers of styrene and the nitrogen-containing intermediates, styrene, unsaturated carboxylic acid esters, etc. There is also a copolymer of the nitrogen-containing monomer and the nitrogen-containing monomer.

(2) Examples of anionic monomers include nitrile-based 111 units such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid, unsaturated dibasic acids, and unsaturated diamyl groups. There are polymers or copolymers of acid anhydrides, or copolymers of styrene and these monomers. Cyclized rubbers and polyesters can also be used as anionic polymers.

In the present invention, as the fine powder dispersion stabilizer, an inorganic fine powder that has the ability to stabilize the dispersion of the monomer composition core in a liquid medium such as an aqueous medium and is sparingly soluble in water is preferably used. . The amount of the dispersant added to the aqueous medium is 1 to 20 parts (more preferably 2 to 1 part) per 100 parts of the monomer composition.
Part 5) is good.

As an anionic fine powder dispersion stabilizer, Aerosil #2
00, #300 (manufactured by Nippon Aerosil Co., Ltd.) Nib Seal E
-22OA (made by Nippon Silica), Fine Seal T-3
Colloidal silica such as No. 2 (manufactured by Tokuyama Soda) is mentioned.

Examples of the cationic fine powder dispersion stabilizer include aluminum oxide, magnesium oxide, and wood-philic positively chargeable silica fine powder such as aminoalkyl-modified colloidal silica treated with a coupling agent. Particularly preferred is a dispersant treated with a coupling agent.

Although a dispersion stabilizer is necessary in the production method of the present invention, it is not necessarily necessary to use a dispersion stabilizer that has counterloading properties in the polar polymer and the liquid medium.

Suitable stabilizers may also be used, such as polyvinyl alcohol, gelatin, methylcellulose, methylhydropropylcellulose, ethylcellulose, carboxymethylcellulose, sodium salts, polyacrylic acid and their salts, starch, gum alginate, zein, casein, phosphorus. According to the present invention, one or a mixture of two or more of tricalcium acid, talc, barium sulfate, bentonite, aluminum hydroxide, ferric hydroxide, titanium hydroxide, sodium hydroxide, etc., is added to an aqueous medium. It may be contained and used within a range that does not adversely affect the manufacturing method.

Further, for uniform dispersion of the inorganic dispersion stabilizer, a surfactant may be used within a range that does not adversely affect the production method of the present invention. This is to promote the intended action of the above-mentioned dispersion stabilizer, and examples thereof include sodium dodecylbenzenesulfonate, sodium tetradecylsulfate, sodium pentadecylsulfate, sodium octylsulfate, and allyl-alkyl-polyether. Sodium sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate,
Sodium caproate, potassium stearate, calcium oleate, 3,3-disulfonic acid, phenylurea-4,4-diazo-bis-amino-8-naphthol-6
-Sodium sulfonate, ortho-carboxybenzene-7zodimethylaniline, 2,2,5.5-tetramethyl, triphenylmethane-4,4-diazo-bis-β
-naphthol-sodium disulfonate, and others. However, it should be noted that when a hydrophilic organic stabilizer or surfactant is used, the moisture resistance of the polymerized toner tends to decrease.

In order to improve granulation properties when a polar group of a polar polymer or cyclized rubber is included in the monomer composition, it is also preferable to add a Brønsted acid such as hydrochloric acid to the aqueous medium. In particular, adding a Brønsted acid such as hydrochloric acid to an aqueous medium can further enhance the effect of an anionic polymer, anionic copolymer or cyclized rubber and a dispersant, especially a cationic fine powder dispersant. is valid.

After the polymerization reaction is completed, polymerized toner particles can be obtained by post-treatment using a conventional method. For example, a polymerized toner can be obtained by washing the produced polymer particles to remove the dispersion stabilizer, collecting them by an appropriate method such as filtration, decantation, centrifugation, etc., and drying them.

The polymerized toner obtained by the production method of the present invention can be applied to known dry electrostatic image developing methods without particular limitations. This polymerized toner can be used, for example, by a two-component development method such as a cascade method, a magnetic brush method, a microtoning method, a two-component AC bias development method; a conductive-component development method, an insulating-component development method;
One-component development method using magnetic toner such as jumping development method; Powder cloud method and fur brush method; Toner is held on a toner carrier by electrostatic force and transported to a developing section for development. Non-magnetic component development method; toner is transported to the developing section by electric field curtain method,
It can be applied to electric field curtain development methods used for development. The toner obtained according to the present invention can be particularly preferably applied to a developing method using a toner with a small particle size of 2 to 8 pm in terms of weight average particle size, which requires a sharp particle size distribution.

Support 11 Hereinafter, the present invention will be explained in more detail based on Examples.

A monomer composition (viscosity 300 cps at 60°C) was prepared by mixing at 30°C. Next, 5 parts by weight of 7-minopropyltoxysilane was added to 100 parts by weight of amino-modified silica (Aerosil #200 manufactured by Nippon Aerosil Co., Ltd.). (reacted) 5g, distilled water 600g, 1/1 ON
20g of hydrochloric acid was heated to a discharge pressure of 580K using a piston-type high-pressure homogenizer (manufactured by Gorlin, model 15M-8TA).
g/cm2. It was dispersed in a dispersion time of 2 minutes to form a liquid dispersion medium. The monomer composition prepared above was added to a stainless steel container with a capacity of 2 cm containing this liquid dispersion medium, and
℃ using a TK homomixer (manufactured by Tokushu Kika Kogyo).
The mixture was granulated by stirring at 0.00 rpm for 15 minutes.

The monomer composition thus granulated was polymerized using a paddle stirring blade at 60° C. for 10 hours.

The polymerized product obtained above was cooled and dehydrated, then washed with a sodium hydroxide solution, dehydrated, and dried to obtain a polymerized toner.

When the particle size of the obtained toner was measured using a Coulter counter (aperture 100 gm), the volume average particle size of the toner was 6.31 Lm, and the particle size was 2.527 Lm.
The volume percentage of fine powder less than m is 6%, 10.081L
The volume percentage of coarse powder of m or more was 3%, which was an extremely narrow particle size distribution.

A monomer composition was prepared by mixing at 30°C.

Amino-modified silica (Aerosil #20 manufactured by Nippon Aerosil)
A piston-type high-pressure homogenizer (manufactured by Gorlin, model: 15M-8TA) at a discharge pressure of 400 Kg/Cm' and a dispersion time of 3 minutes to obtain a liquid dispersion medium. The monomer composition prepared above was added to a stainless steel container with a capacity of 2 cm containing this liquid dispersion medium, and the monomer composition was heated at 60°C using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 10.0 OOrp. After stirring for 20 minutes and granulating, the monomer composition was polymerized in the same manner as in Example 1.

The resulting polymerized product was cooled, dehydrated, washed with a sodium hydroxide solution, dehydrated, and dried to obtain a polymerized toner.

When the particle size of the obtained toner was measured using a Coulter counter (aperture 50 p-m), the volume average particle size of the toner was 5.3 p.m, and the particle size was 2.52 μm.
The volume percentage of fine powder below m is 3%, 10.08pm
The volume percentage of the above coarse powder was 3%, which was an extremely narrow particle size distribution.

Support 1" Styrene 90g 2-ethylhexyl acrylate 10g 2.2'-azobis-3g (2,4-dimethylvaleronitrile) 2.2'-azobis tgisobutyronitrile styrene-dimethylamino 15g ethyl methacrylate copolymer ( Copolymerization ratio 9: l, Mw=75.000) Charge controllable organometallic complex 2g (Orient Chemical, Pontron E-81) Carbon black
The monomer composition (
A viscosity of 300 cps at 80°C was prepared.

Next, the monomer composition prepared above was added to a liquid dispersion medium in which 5 g of colloidal silica (Aerosil #200 manufactured by Nippon Aerosil Co., Ltd.) and 600 g of water were dispersed in the same manner as in Example 1. After granulation in the same manner as above, polymerization was carried out at 60° C. for 10 hours using a paddle blade stirring blade.

The resulting polymerized product was cooled and dehydrated, then washed with a sodium hydroxide solution, dehydrated, and dried to obtain a polymerized toner.

When the particle size of the obtained toner was measured with a Coulter counter (aperture 100 μm), the volume average particle size was 5.8 gm, and the volume percentage of fine powder with a particle size of 2.52K11 or less was 6%, which was 10.08 gm or less. The volume percent of the coarse powder of No. 1- was 3%, which was extremely narrow with a particle size of 4j.

A monomer composition (viscosity at 80°C: 100 cps) was prepared by mixing at 30°C. Next, 6 g of amine-modified silica (reacted with 5 parts by weight of aminopropyltriethoxysilane and 100 parts by weight of Aerosil #200 manufactured by 11th Ki Aerosil Co., Ltd.), 600 g of distilled water, and 1/1 O
The monomer composition prepared above was added to a liquid dispersion medium in which 20 g of N-hydrochloric acid was dispersed in the same manner as in Example 1.
The monomer composition was granulated and polymerized in the same manner.

The resulting polymerized product was cooled and dehydrated, then washed with a sodium hydroxide solution, dehydrated, and dried to obtain a polymerized toner.

When the particle size of the obtained toner was measured with a Coulter counter (aperture 100 gm), the volume average particle size was 5.57 zm, and the volume percentage of fine powder with a particle size of 2.52 mm or less was 6%, 10°08 JLI1. The volume percentage of the above coarse powder was 3%, which was an extremely narrow particle size distribution.

Melon comparison 1 The amount of the 7-mino modified silica used in Example 1 was 10 g, and the dispersion stabilizer was not dispersed using a high-pressure homogenizer, except that the particles were dispersed for 60 minutes using a TK homomixer. A polymerized toner was obtained in the same manner as in Example 1.

The particle size of the obtained polymerized toner is such that the volume average particle size is 11.0.
7 ha and 1 grain size 6.3511. The volume percentage of fine powder of 16 p or less was 15%, and the volume percentage of coarse powder of 16 p, m or more was 15%, and the particle size distribution was wider than in Example 1.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view showing an example of a high-pressure homogenizer used in the dispersion process of the present invention, and FIGS. 2 to 4 are process diagrams showing embodiments of the manufacturing method of the present invention. be. ■... Fine powder dispersion stabilizer 2... Dispersion medium 3... Liquid dispersion medium 4... High pressure section 5... Valve seat 6... Valve 7... Gap 8... Collision member 9...Low pressure part υ": Figure 1

Claims (1)

[Claims] 1. Liquid dispersion medium containing fine powder dispersion stabilizer at 10K
A dispersion step in which the dispersion stabilizer is dispersed by applying pressure to g/cm^2 or more and passing through a narrow passage; and polymerization in the liquid dispersion medium in which the dispersion stabilizer is dispersed in the above dispersion step. a granulation step of dispersing and suspending a monomer composition containing at least a coloring agent and a colorant, and forming toner particles by suspension polymerizing the granulated monomer composition; 1. A method for producing a toner for developing an electrostatic image, comprising at least the following steps: 2. In the granulation step, the volume average particle diameter of the toner is 1 to 20.
2. The method for producing a toner for developing an electrostatic image according to claim 1, which comprises a granulation step of granulating the monomer composition to a particle size of .mu.m.