JPH0350563A - Production of polymerized toner - Google Patents

Abstract

PURPOSE:To obtain the toner which is improved in triboelectrostatic chargeability and moisture resistance by making an amine compd. to coexist in a suspension polymn. which is formed by suspension polymn. of a monomer compsn. contg. a polymerizable monomer and coloring agent and in which polyvinyl alcohol (PVA) is used as a suspension stabilizer. CONSTITUTION:The PVA is used as the suspension stabilizer and the compsn. is polymerized in the copresence of the suspension polymn. at the time of subjecting the polymerizable monomer and coloring agent to granulation and suspension polymn. in a medium having miscibility with water, etc. Arom. amine derivatives, such as aniline and N-methyl anihile, are preferably used as the amine compd. The formation of the film of the PVA is suppressed by the addi tion of the amine compd. regardless of the degree of polymn. and the rate of saponification of PVA. The toner which is improved in triboelectrostatic chargeability and moisture resistance, etc., is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a toner for obtaining clear images, and particularly relates to a method for producing a toner for obtaining clear images, and in particular, polyvinyl alcohol (hereinafter referred to as PVA), which is a suspension stabilizer for polymer particles. ), and relates to a method for producing a polymerized toner that prevents the adhesion of .

[Prior Art] [Problem to be Solved by the Invention] Toners conventionally used in electrophotography are generally made by kneading additives such as a coloring agent such as carbon plaque and a charge control agent into a thermoplastic resin. After being uniformly dispersed, it is pulverized using a pulverizer, and then classified using a classifier to the particle size suitable for the toner. There are several problems with toner produced by this pulverization method. That is, in the toner manufactured by this pulverization method, the material must have a certain degree of pulverization so that it can be easily pulverized. However, if a material that is too brittle is used, the toner becomes too finely divided, and in order to obtain the final toner with the appropriate particle size distribution, the fine particles must be removed, which increases manufacturing costs. There is.

Moreover, such toner may be further pulverized in the developing device of a copying machine during the process of continuous copying. In addition, if a low melting point material or a pressure fixing material is used for the toner to improve heat fixability, the toner may fuse in the crusher or classifier, making continuous production impossible. arise. In order to solve these problems, it has been proposed to produce polymerized toners from polymerizable monomers by a suspension polymerization method. (Tokuko Sho 51-14895
(Refer to Japanese Patent Application Laid-open No. 57-53756, etc.) The conventional method for producing a polymerized toner by a general suspension polymerization method involves adding a polymerizable monomer and a colorant (mainly containing at least a carbon blank). , generated when the polymerization initiator in the reaction system is decomposed by heat when granulated to the particle size of the toner using an appropriate stirrer in a water-miscible medium containing at least a suspension stabilizer. A polymerizable monomer is polymerized by radicals to form a polymer, and a polymerized toner is manufactured. That is, this polymerized toner does not need to be brittle, and since it is spherical in shape, the polymerized toner has characteristics such as excellent fluidity and uniform triboelectric charging properties.

However, when producing polymerized particles having a desired particle size for a toner by suspension polymerization, selection of a suspension stabilizer becomes an important point. That is, the suspension stabilizer has a large effect on particle size, particle size distribution, yield, post-treatment method, etc. Especially 5-10
There is a need for a suspension stabilizer that has a large suspension stabilizing ability to stabilize droplets on the order of micrometers until the end of polymerization, and that has good removal, ie, washability, of the suspension stabilizer after polymerization.

Polyvinyl alcohol generally used for suspension polymerization is
It has a high suspension stability ability and can stably complete the polymerization of droplets having a desired particle size in the toner, but the surface of the obtained polymer particles is covered with a polyvinyl alcohol film,
Surface physical properties will largely depend on polyvinyl alcohol. In addition, since it is difficult to effectively remove the polyvinyl alcohol that coats the particle surface, these polymer particles deteriorate in surface resistance, triboelectric charging properties, moisture resistance, etc., which are important physical properties of toner, and are not required as toners. performance cannot be satisfied.

[Means for Solving the Problems] [Operation] The present invention has been made as a result of intensive research in view of the above circumstances.
By coexisting an amine compound in a suspension polymerization system that uses polyvinyl alcohol as a suspension stabilizer, formation of a polyvinyl alcohol film on the surface of the polymer particles is suppressed and prevented, and triboelectric resistance and moisture resistance are improved. It has been found that a polymerized toner with good fluidity, storage stability, etc. can be produced.

That is, the present invention provides 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, and the method comprises using polyvinyl alcohol as a suspension stabilizer. This is a method for producing a polymerized toner, characterized in that polymerization is carried out in the presence of an amine compound in a suspension polymerization system.

Next, each material used in the present invention and its effects will be explained in detail.

The following percentages and parts are based on weight. Polymerizable monomer Examples of the polymerizable monomer include styrene, 01-methylstyrene, m-methylstyrene, p-methylstyrene, and p-methylstyrene.
-Methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p- Styrene and derivatives thereof such as n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl buttomide; organic acid vinyl esters such as vinyl acetate, vinyl brobionate, vinyl benzoate;
Methacrylic acid, methyl methacrylate, ethyl methacrylate, probyl methacrylate, n-butyl methacrylate,
Methacrylic acid and its derivatives such as n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; acrylic acid, methyl acrylate, acrylic Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, probyl acrylate, n-acrylate
-Acrylic acid and its derivatives such as octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl Vinyl ketones such as methyl ketone and vinyl isopropenyl ketone; N-vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; often vinylnaphthalene; acrylonitrile, methacrylnitrile, acrylamide Polymerizable monomers such as

These polymerizable monomers can be used alone or in various combinations of two or more, if necessary. However, among the above-mentioned polymerizable monomers, it is preferable to use styrene or styrene-based monomers alone or in combination with other monomers in order to improve the development characteristics and durability of the toner.

colorant Carbon blank is suitable as a coloring agent.

The carbon blank to be used can be used regardless of the number, average particle size, oil absorption amount, and pH, and the following are commercially available products.

REGAL 400 manufactured by Cavoft in the United States,
660, 330, 300, SRF-3, STERLING So, V, NS, R;:]O
RAVEN H manufactured by Nvia Carbon Japan Co., Ltd.
20, MT-P, 410, 420, 430,
450, 500, 760, 780, 1000, 1
035, 1060, 1080; Manufactured by Mitsubishi Kawei Industries, Ltd. #
10B, #5B, #40, #2400B, M
Examples include A-100. Further, these carbon blacks can be used alone or in various combinations of two or more types.

As a coloring agent other than carbon blank, it can be dispersed in a monomer composition and has a clear color when used as a toner.
A color exhibiting excellent stability over time is used. Examples of such coloring agents include phthalocyanine pigments, Rhoda ξ lake pigments, azo lake pigments, iron oxides, titanium oxides, alumina, barium sulfate, and the like.

The amount of colorant added is 1 to 40 parts per 100 parts of polymerizable monomer.
parts, preferably 5 to 20 parts. In addition, in the present invention, in order to improve thermal stability and anti-offset properties, a low softening point compound with mold release properties such as waxes such as paraffin wax, low molecular weight polyethylene, and low molecular weight polypropylene is used in the monomer composition. It can be added to things.

Furthermore, in the present invention, suspension polymerization may be carried out with the addition of a crosslinking agent in order to improve buffing resistance and durability. As such a crosslinking agent, known ones such as divinylbenzene can be used. Furthermore, in the present invention,
If necessary, a known charge control agent may be added to the monomer composition, or the surface of the polymerized toner particles may be treated with a solution dissolved in an organic solvent. Examples of such charge control agents include metal complexes of organic compounds having carboxyl groups, sulfonic acid esters, or nitrogen-containing groups, metal alloy dyes, and the like.

Polymerization initiator The polymerization initiator used in the present invention is preferably soluble in the polymerizable monomer.
,2゜-゛Azobisisobutyronitrile, 2.2'-
Azobis(2,4 dimethylvaleronitrile), 2.2'
- Azobis-4-methoxy-2,4-dimethylvaleronitrile, other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, isoprobyl peroxy carbonate, and other peroxide polymerization initiators. It will be done.

However, penzoyl peroxide-based polymerization initiators produce carboxylic acids such as benzoic acid as by-products when decomposed, which may have an adverse effect on toner storage stability.
Furthermore, since there are drawbacks such as generation of aromatic odor, azo polymerization initiators are preferred.

In the present invention, for the purpose of controlling molecular weight and molecular weight distribution,
Alternatively, for the purpose of controlling the reaction time, two or more of the above polymerization initiators can be used in combination in various compositions. Furthermore, 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 0.1 to 20 parts, preferably 1 to 10 parts, based on 100 parts of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 part, the polymerization time will be long and the molecular weight of the polymerized compound will become too high. On the other hand, if the polymerization initiator exceeds 20 parts, the molecular weight of the polymerized raw material becomes too low, which is not preferable.

Partially saponified polyvinyl alcohol, which is a suspension stabilizer, is useful for suspension polymerization, but it has been found that contamination of polymer particles, particularly in the form of a polyvinyl alcohol film, is significant. The present invention suppresses and prevents contamination by polyvinyl alcohol by adding an amine compound to this suspension polymerization system. Examples of the amine compound include the following. Namely, aniline, N-methylaniline, 4-nitroaniline, 0-
Aromatic amine derivatives such as phenylene diamine are preferably used.

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

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

When using the Adan compound in the present invention, it was possible to prevent polyvinyl alcohol from contaminating the surface of the polymer particles by adding it to the dispersed phase (monomer phase). In this case, it is preferable that the fruit compound is slightly soluble in water, and that the pKa value is 5 or less to prevent agglomeration and aggregation of particles due to stabilization of the suspension system, and to improve particle formation. It is preferable because precepts are possible. Further, it is preferable that the concentration of the saturated aqueous solution at 25° C. be 5% or less, since this also stabilizes the suspension system and makes it possible to produce good particles without agglomeration or agglomeration. It can be added to either the dispersed phase (monomer phase) or the continuous phase (aqueous phase) or both, but it is especially possible to obtain a large pollution control effect by adding it to the dispersed phase (monomer phase). The amount of the amine compound used in the present invention is such that when added to the monomer phase, the concentration in that phase is 0.05% to 5%, preferably 0.1% to 3%.Concentration of the amine compound If it is less than 0.05%, polyvinyl alcohol contamination is observed, and if it exceeds 5%, there is a strong tendency to inhibit polymerization, making it impossible to obtain a polymer with the desired molecular weight. , cleaning of polymer particles,
Due to drying issues, the smaller the particle size of the polymer particles, the more effective it is. [Example] An example will be explained below. Example 1 10 g of n-butyl acrylate and 20 g of carbon black (manufactured by Mitsubishi Kaoru Co., Ltd., #40) were mixed and dispersed in 90 g of styrene at room temperature for about an hour using a paint conditioner. After purging with nitrogen gas for 30 minutes, at 100° C. or higher, 4 g of 2.2°-azobisisobutyronitrile was added to the above monomer composition of the polymerizable monomer and dissolved to form the monomer. Adjusted the bottom.

Next, polyvinyl alcohol (manufactured by Unitika, UP240)
G) 10g and 4g of sodium sulfate were dissolved in 500g of distilled water, put into a separable flask with a volume of 11L, added the monomer m prepared above, and mixed with TK-Homo mixer (Tokushu Kika Kogyo Co., Ltd.). 10000r using
pm for about 20 minutes, and then the monomer set t7. Polymerized things.

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

When the particle size of the obtained polymerized toner was measured using a Coulter counter (aperture - 100μIl+), it was found that:
The volume average particle diameter of the toner was 10 μm.

When this polymerized toner was observed under an optical microscope (450x magnification), each particle of the toner had an almost completely black spherical shape, and no uneven distribution of carbon blanks was observed within the toner particles.Furthermore, when observed using a scanning electron microscope, , S.E.
As shown in the M photograph (Figure 1), no polyvinyl alcohol coating was observed on the particle surface.

Furthermore, using this toner, an image quality test was conducted using a commercially available copier (manufactured by Sharp Corporation, SF8260) at a room temperature of 30°C and humidity of 80%, and images with good density and image quality were obtained. .

Example 2 Surface-treated carbon black was obtained in the same manner as in Example 1. This carbon blank will be used below.

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

Next, using this monomer composition, a polymerized toner was obtained using the same formulation and method as in Example 1.

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

When this polymerized toner was observed under an optical microscope (450) magnification, each particle of the toner was almost completely black and spherical.
No uneven distribution of carpon cracks within the toner particles was observed. Furthermore, when observed with a scanning electron microscope,
As shown in the SEM photograph (Fig. 1), no polyvinyl alcohol coating was observed on the particle surface.

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

[Comparative example]

A polymerized toner was obtained by carrying out suspension polymerization in the same manner as in Example 1 except that no amine compound was added.

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 it was observed under an optical microscope (4
When observed at a magnification of 50), each particle of the toner was black and amorphous, and a transparent film was observed on the outline of the particle. Further observation using a scanning electron microscope revealed a polyvinyl alcohol coating on the particle surface, as shown in the SBM photograph (Figure 2).

Furthermore, using this toner, an image formation test was attempted using a commercially available copying machine (manufactured by Sharp Corporation, SF8260) at a room temperature of 30''C and humidity of 80%, but a good image could not be obtained. Ta.

〔Effect of the invention〕

The present invention suppresses and prevents the formation of a film of polyvinyl alcohol, which is a suspension stabilizer, on the surface of polymer particles by adding an amine compound to a suspension polymerization system, thereby obtaining a toner with improved triboelectric charging properties, moisture resistance, etc. be able to.

[Brief explanation of drawings]

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

Claims (3)

[Claims] (1) When producing a polymerized toner by suspension polymerizing a monomer composition containing at least a polymerizable monomer and a colorant, the suspension polymerization system uses polyvinyl alcohol as a suspension stabilizer. , a method for producing a polymerized toner, characterized in that polymerization is carried out in the coexistence of an amine compound. (2) The manufacturing method according to claim 1, wherein the amine compound has a pKa value of 5 or less. (3) The manufacturing method according to claim 1, wherein the concentration of the saturated aqueous solution of the amine compound at 25°C is 5% or less.