JPH0810352B2 - Method for producing polymerized toner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a toner for obtaining a clear image, and particularly polyvinyl alcohol (hereinafter referred to as PVA) which is a suspension stabilizer for polymer particles. The present invention relates to a method for producing a polymerized toner in which the adhesion of a) is prevented.

[Prior Art] [Problems to be Solved by the Invention] Toners conventionally used in electrophotography and the like are generally kneaded with additives such as a coloring agent such as carbon black and a charge control agent in a thermoplastic resin, It is manufactured by a so-called pulverization method in which the particles are uniformly dispersed, then pulverized by a pulverizer, and classified by a classifier to have a particle size suitable for a toner. There are several problems with the toner produced by this crushing method.

That is, in the toner produced by this pulverization method, the material must be brittle so that the material can be pulverized to some extent. However, when a material having too high brittleness is used, the toner is too finely pulverized, and in order to finally obtain a toner having an appropriate particle size distribution, the fine powder has to be removed, resulting in a high manufacturing cost. There is. Further, such toner may be further pulverized in the process of continuous copying in the developing device of the copying machine. Further, in order to improve the heat fixing property, when a low melting point material is used for the toner or a pressure fixing material is used, the toner may cause a fusion phenomenon in the crushing device or the classifier, which may make continuous production impossible. Occurs. In order to solve such a problem, it has been proposed to produce a polymerized toner from a polymerizable monomer by a suspension polymerization method. (Japanese Patent Publication Sho 51
-14895, JP-A-57-53756, etc.) A conventional method for producing a polymerized toner by a suspension polymerization method is a polymerizable monomer and a colorant (mainly containing at least carbon black). Generated when the polymerization initiator in the reaction system is decomposed by heat in the water-miscible medium containing at least a suspension stabilizer and the like by using an appropriate stirrer By radicals that
A polymerized toner is manufactured by polymerizing a polymerizable monomer to form a polymer. That is, the polymerized toner does not need to have brittleness, and since it has a spherical shape, the polymerized toner has characteristics such as excellent fluidity and uniform triboelectricity.

However, when producing polymerized particles having a desired particle size in a toner by suspension polymerization, selection of a suspension stabilizer is an important point. That is, the suspension stabilizer has a particle size, a particle size distribution,
The yield and the post-treatment method are greatly affected. Especially 5-10
There is a demand for a suspension stabilizer having a large suspension stability that stabilizes droplets of about μm until the end of polymerization, and removal of the suspension stabilizer after polymerization, that is, good washability.

Generally, polyvinyl alcohol used for suspension polymerization has a large suspension stability and can stably complete the polymerization of droplets having a desired particle size in the toner. It is covered with a film, and the physical properties of the surface depend largely on polyvinyl alcohol. Further, since it is difficult to effectively remove the polyvinyl alcohol coated on the particle surface, these polymer particles are deteriorated in surface resistance, triboelectric charging property, moisture resistance, etc., which are important as physical properties of the toner, and are required as a toner. I cannot satisfy the required performance.

[Means for Solving the Problems] [Action] The present invention has been made as a result of earnest research in view of the above situation, and coexists an amine compound in a suspension polymerization system using polyvinyl alcohol as a suspension stabilizer. It was found that, by suppressing the formation of polyvinyl alcohol film on the surface of the polymer particles, friction resistance and humidity resistance are improved, and further good polymerized toner such as fluidity and storability can be produced. It was

That is, the present invention is a method for producing a polymerized toner in which a monomer composition containing at least a polymerizable monomer and a colorant is subjected to suspension polymerization, wherein polyvinyl alcohol is used as a suspension stabilizer and a suspension stabilizer. A method for producing a polymerized toner is characterized in that an amine compound consisting of an aromatic amine derivative is allowed to coexist in the suspension polymerization system and polymerized.

Next, each material used in the present invention and the function and the like thereof will be described in detail.

 Below,% and parts are based on weight.

Polymerizable Monomer Examples of the polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,
p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, p Styrene and its derivatives such as -n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene and pn-decyl styrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; vinyl acetate, vinyl propionate,
Vinyl benzoate and other organic acid vinyl esters; methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid. Methacrylic acid and its derivatives such as stearyl, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; acrylic acid, methyl acrylate,
Acrylics such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate Acids and their derivatives; vinyl methyl ether, vinyl ethyl ether,
Vinyl ethers such as vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone and vinyl isopropenyl ketone; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone; vinyl naphthalenes Polymerizable monomers such as acrylonitrile, methacrylonitrile and acrylamide may be mentioned.

These polymerizable monomers can be used alone or in combination of two or more kinds in various compositions as required.

However, among the above-mentioned polymerizable monomers, it is preferable to use styrene or a styrenic monomer alone or in combination with other ones from the viewpoint of improving the developing characteristics and durability of the toner.

Colorant Carbon black is suitable as the colorant. The carbon black used is number, average particle size, oil absorption, pH
Although it can be used regardless of, the following are commercially available products.

US Cabot Corp. Regal 400, 660, 33
0, 300, SRF-3, STERLING SO, V, NS,
R; Raven H from Columbia Carbon Japan Co., Ltd.
20, MT-P, 410, 420, 430, 450, 500, 760, 780, 100
0, 1035, 1060, 1080; Mitsubishi Kasei Co., Ltd. # 10B, # 5
B, # 40, # 2400B, MA-100 and the like. These carbon blacks may be used alone or in combination of two or more in various compositions.

As the colorant other than carbon black, a colorant that is dispersible in the monomer composition, exhibits a clear color when used as a toner, and has excellent stability over time is used. As such a colorant, a phthalocyanine-based pigment,
Examples thereof include rhodamine lake pigment, azo lake pigment, iron oxide, titanium oxide, alumina, barium sulfate and the like.

The amount of colorant added is 1 to 40 with respect to 100 parts of the polymerizable monomer.
Parts, preferably 5 to 20 parts are used.

Further, in the present invention, in order to improve thermal stability and offset resistance, waxes such as paraffin wax, low molecular weight polyethylene, low molecular weight polypropylene and the like having a low softening point compound having releasability as a monomer composition. May be added to.

Further, in the present invention, in order to improve blocking resistance and durability, a crosslinking agent may be added to carry out suspension polymerization. As such a crosslinking agent, a known one such as divinylbenzene can be used.

Furthermore, in the present invention, a known charge control agent may be added to the monomer composition, if necessary, or the surface of the polymerized toner particles may be treated with a solution dissolved in an organic solvent. As such a charge control agent, a carboxyl group,
Examples include metal complexes of sulfonates or organic compounds having a nitrogen-containing group, metal-containing dyes, and the like.

Polymerization Initiator The polymerization initiator used in the present invention is preferably soluble in the polymerizable monomer. As such a polymerization initiator,
2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4dimethylvaleronitrile), 2,2'-azobis-4
-Methoxy-2,4-dimethylvaleronitrile, other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate and other peroxide polymerization initiators.

However, the benzoyl peroxide-based polymerization initiator is
When decomposed, a carboxylic acid such as benzoic acid is by-produced, which may adversely affect the preservability of the toner, and also has a drawback such as generation of an aromatic odor. preferable.

In the present invention, for the purpose of controlling the molecular weight and the molecular weight distribution, or for the purpose of controlling the reaction time, two or more of the above polymerization initiators can be used in combination in various compositions. Further, if necessary, a water-soluble polymerization initiator such as ammonium persulfate or potassium persulfate may be used in combination.

The amount of the polymerization initiator used is 100 parts of the polymerizable monomer.
It is 0.1 to 20 parts, preferably 1 to 10 parts. Polymerization initiator
If it is less than 0.1 part, the polymerization time will be long and the molecular weight of the polymerization product will be too high. On the other hand, when the amount of the polymerization initiator exceeds 20 parts, the molecular weight of the polymerization product becomes too low, which is not preferable.

As for the polyvinyl alcohol which is a suspension stabilizer, it is recognized that the partially saponified polyvinyl alcohol useful for suspension polymerization is conspicuously contaminated with polymer particles, particularly the polyvinyl alcohol film formation.

The present invention suppresses contamination with polyvinyl alcohol by adding an amine compound to this suspension polymerization system,
The amine compounds, which are to be prevented, include the following.

That is, aromatic amine derivatives such as aniline, N-methylaniline, 4-nitroaniline and o-phenylenediamine are preferably used.

The above amine compounds can be used alone or in combination of two or more in various compositions.

As the polyvinyl alcohol used in the present invention, commercially available polyvinyl alcohol can be used as it is, and film formation is suppressed by adding an amine compound regardless of the degree of polymerization and the degree of saponification.

When the amine compound is used in the present invention, by adding it to the dispersed phase (monomer phase), it is possible to prevent polyvinyl alcohol from contaminating the surface of the polymer particles.

In this case, it is preferable that the amine compound be slightly soluble in water, and that the pKa value of 5 or less can prevent agglomeration and aggregation of particles due to the stabilization of the suspension system, and can produce good particles. Therefore, it is preferable. Further, it is preferable that the concentration of the saturated aqueous solution at 25 ° C. is 5% or less because it also stabilizes the suspension system and can produce good particles without causing agglomeration or aggregation. And dispersed phase (monomer phase)
Alternatively, it can be added to either or both of the continuous phase (water phase), but in particular, when it is added to the dispersed phase (monomer phase), a great effect of suppressing contamination can be obtained.

When the amine compound used in the present invention is added to the monomer phase, the concentration in the phase is 0.05% to 5%, preferably 0.1% to 3%. When the concentration of the amine compound is less than 0.05%, the polyvinyl alcohol is contaminated, and when it exceeds 5%, the polymerization tends to be inhibited and the polymer having the desired molecular weight cannot be obtained.

Further, such an effect of preventing pollution is obtained by washing the polymer particles,
From the problem of drying, the smaller the particle size of the polymer particles, the more effective.

〔Example〕

 Examples will be described below.

Example 1 90 g of styrene, 10 g of n-butyl acrylate and 20 g of carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) were mixed and dispersed for about 1 hour at room temperature using a paint conditioner, and then placed in a separable flask. After substituting with nitrogen gas for about 30 minutes, the surface of the carbon black was treated with the polymerizable monomer at 100 ° C. or higher to obtain a surface-treated carbon black. Hereinafter, this carbon black will be used.

A monomer composition was prepared by adding 5 g of 2,2'-azobisisobutyronitrile to the above monomer composition and dissolving them.

Next, polyvinyl alcohol (UP240G manufactured by Unitika Ltd.)
10 g and 4 g of sodium sulfate were dissolved in 500 g of distilled water, placed in a separable flask having a volume of 1 L, the monomer composition adjusted as above was added, and TK-Homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) Granulate at 10,000 rpm for about 20 minutes, then use a flat plate turbine at 60 ° C for 6 hours, then 80
The monomer composition was polymerized under the condition of 1 ° C. for 1 hour.

The polymer particles obtained above were washed and dried by a conventional method to obtain a polymerized toner of the present invention.

When the particle size of the obtained polymerized toner was measured by using a Coulter counter (aperture 100 μm), the volume average particle size of the toner was 10 μm.

When the polymerized toner was observed with an optical microscope (450 ×), each particle of the toner showed almost a completely black spherical shape, and uneven distribution of carbon black was not found in the toner particle. Further observation with a scanning electron microscope revealed that SEM
As shown in the photograph (Fig. 1), no polyvinyl alcohol coating was found on the surface of the particles.

Further, using this toner, an image forming test was conducted using a commercially available copying machine (Sharp, SF8260) at room temperature of 30 ° C. and humidity of 80%. As a result, an image with good density and image quality was obtained.

Example 2 A surface-treated carbon black was obtained in the same manner as in Example 1. Hereinafter, this carbon black will be used.

A monomer composition was prepared by adding 5 g of 2,2'-azobisisobutyronitrile to the above monomer composition and dissolving them.

Next, using this monomer composition, a polymerized toner was obtained in the same manner as in Example 1 except for using the same composition.

When the particle size of the obtained polymerized toner was measured by using a Coulter counter (aperture 100 μm), the volume average particle size of the toner was 10 μm.

When this polymerized toner was observed with an optical microscope (450), each particle of the toner was almost completely black and no uneven distribution of carbon black was observed in the toner particle. Further observation with a scanning electron microscope revealed that SEM
As shown in the photograph (Fig. 1), no polyvinyl alcohol coating was found on the surface of the particles.

Further, using this toner, an image forming test was conducted using a commercially available copying machine (Sharp, SF8260) at room temperature of 30 ° C. and humidity of 80%. As a result, an image with good density and image quality was obtained.

[Comparative example]

Suspension polymerization was carried out in the same manner as in Example 1 except that the amine compound was not added to obtain a polymerized toner.

When the particle size of the obtained polymerized toner was measured using a Coulter counter (aperture 100 μm), the volume average particle size of the toner was 18 μm.

The appearance of this polymerized toner was grayish white, and when observed under an optical microscope (450), each particle of the toner showed a black irregular shape, and a transparent film was observed on the contour of the particle.
Further observation with a scanning electron microscope confirmed a polyvinyl alcohol film on the surface of the particles as shown in the SEM photograph (Fig. 2).

Further, using this toner, an image forming test was tried using a commercially available copying machine (SF8260, manufactured by Sharp Corporation) under the conditions of room temperature of 30 ° C. and humidity of 80%, but a good image could not be obtained.

〔The invention's effect〕

The present invention provides a toner in which the addition of an amine compound to a suspension polymerization system prevents the formation of a film of polyvinyl alcohol, which is a suspension stabilizer, on the surface of polymerized particles, and improves triboelectrification and moisture resistance. be able to.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing the structure of polymer particles obtained by the present invention, and FIG. 2 is an electron micrograph showing the structure of polymer particles obtained by a conventional method.

 ─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP 62-67563 (JP, A) JP 1-257858 (JP, A) JP 1-137268 (JP, A) JP 54- 76233 (JP, A)

Claims (3)

[Claims] 1. A suspension polymerization method, wherein polyvinyl alcohol is used as a suspension stabilizer in the production of a polymerized toner by suspension polymerization of a monomer composition containing at least a polymerizable monomer and a colorant. A method for producing a polymerized toner, characterized in that an amine compound comprising an aromatic amine derivative is allowed to coexist in a system and polymerized. 2. The method according to claim 1, wherein the amine compound has a pKa value of 5 or less. 3. The method according to claim 1, wherein the concentration of the saturated aqueous solution of the amine compound at 25 ° C. is 5% or less.