JPH0723973B2 - Method for producing suspension polymerization toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a toner used for developing a latent image in an electrophotographic method, an electrostatographic method, an electrostatic printing method, or the like, and more specifically, The present invention relates to a method for producing a so-called polymerized toner produced by turbidity polymerization.

[Background Art] Conventionally, a toner has generally been manufactured by melting and mixing a colorant and other additives in a thermoplastic resin and uniformly dispersing them, and then producing a toner having a desired particle diameter by a fine pulverizer, a classifier, or the like. .

However, in this manufacturing, a large amount of energy is required in the melting, mixing and crushing processes. Further, the toner obtained by using the pulverizing method must have brittleness so that the material can be easily pulverized to some extent. However, if the toner is too brittle, it will be too finely pulverized, and it will be necessary to carry out fine powder cutting in order to obtain a toner having an appropriate particle size distribution, which leads to cost up. Therefore, in order to overcome the problems of the pulverization method, a method for producing a toner called a polymerized toner by suspension polymerization has been proposed. The polymerized toner is produced by suspending a mixture in which a polymer monomer, a polymerization initiator and other additives are mixed in an aqueous medium and polymerizing in a particle state of a desired particle size. Since the obtained polymerized toner particles are spherical, they generally have better fluidity than toners obtained by the pulverization method.

2. Description of the Related Art In recent years, as image forming apparatuses such as copying machines have become faster and more multifunctional, there has been an increasing demand for improved performance of toner used therein. That is, with the increase in speed, a low melting point toner that is fixed by low heat energy is required, but such a toner generally has a low Tg, and due to mechanical pressure in the developing process, adhesion and aggregation of the toners with each other and , Developing device,
Adhesion to the photosensitive drum and cleaning blade is also likely to occur. Further, with respect to the developing characteristics, it is desired that the developing characteristics are further improved with the increase in speed, and if the developing characteristics are inferior, image defects such as fog, greasiness, and density decrease easily occur.

The present invention provides a method for producing a toner having improved characteristics required for such a toner. Furthermore,
The present invention provides a method for producing a polymerized toner having a heat treatment step for polymerized toner.

Specifically, the present invention provides a suspension-polymerized toner formed of polymer particles containing a colorant obtained by separating from an aqueous medium after the suspension polymerization step, at a temperature of 35 ° C to 75 ° C at 30 ° C. The present invention relates to a method for producing a suspension-polymerized toner, which comprises removing residual monomers remaining in the polymer particles by heating for at least a minute.

That is, in the production of the polymerized toner of the present invention, the polymerized particles obtained by removing the aqueous solvent after the completion of the polymerization process are heat-treated to provide a toner having improved fluidity and developing characteristics. .

In the present invention, the various properties of the polymerized toner are improved by being subjected to the heat treatment, probably because the residual monomer is removed by the heat treatment, the rearrangement of the polymer chain in the polymerized toner, the polymer functional period It is presumed that the coordination and the like improve the mechanical strength of the polymer, further prevent the aggregation of toner particles, and make the charging characteristics of the toner particles uniform.

The method for producing the polymerized toner of the present invention includes a monomer, a polymerization initiator,
A mixture obtained by mixing additives such as a coloring material, a magnetic material, a resin, a release agent, a cross-linking agent, and a household appliance control agent is stirred and mixed in an aqueous medium to form fine particles, which are obtained by polymerizing in the fine particle state. The polymer particles thus obtained are separated from the aqueous solvent, and then the particles are treated in the vicinity of Tg of the resin for toner (Tg ± 30
℃). It can be achieved by performing heat treatment at 35 ° C. (preferably 40 ° C.) or more and 75 ° C. or less for 30 minutes or more.

Heating at a temperature higher than about Tg (glass transition point) of a resin used as a toner resin at 75 ° C. or higher is not preferable because the development characteristics are deteriorated due to cohesive adhesion of polymer particles.
Also, the heat treatment at less than 35 ° C. does not provide the above-mentioned effects. The more preferable heating temperature is 40 to 70 ° C., and the heat treatment effect is satisfactorily achieved. Furthermore, the heating time
30 minutes or more, preferably 1 hour or more, more preferably 2 hours or more. The heating temperature and heating time are from 35 ° C to
It is appropriately determined within the range of 75 ° C. and 30 minutes or more, and within the range where polymerization and particles do not aggregate and adhere to each other.

In this heat treatment, the removal of the residual monomer may be further promoted by performing the treatment under reduced pressure and / or stirring the polymer particles while leaving voids between the particles.

As the monomer used in the present invention, a polymerized monomer having a double bond is used, and examples thereof include styrene, o-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene and p-tert-butyl. Styrene, pn-dodecyl styrene, p-chlorostyrene,
Styrenes such as p-phenylstyrene, vinylnaphthalenes, ethylene unsaturated monoolefins such as ethylene, propylene and isobutylene; vinyl chloride, vinyl acetate,
Vinyl esters such as vinyl butyrate and vinyl benzoate;
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, propyl acrylate,
N-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-chloromethyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid Propyl acid, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylamino methacrylate Α-Methylene aliphatic monocarboxylic acid esters such as ethyl, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide; vinyl Vinyl ethers such as methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl methyl ketone, vinyl hexyl ketone,
Vinyl ketones such as methyl isopropenyl ketone; N-
Examples thereof include N-vinyl compounds such as vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidene. You may use these 1 type (s) or 2 or more types. Further, one or more kinds of polymers such as polar polymers having polar groups such as carboxyl group, amino group and substituted amino group may be contained in these polymerizable monomers.

As the polymerization initiator used in the present invention, for example, asobisisobutyronitrile (AIBM), benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, quinene hydroperoxide, 2,4-dichlorylbenzoyl peroxide, It can be performed using lauroyl peroxide or the like.

In the present invention, a cross-linked polymer may be prepared by using an appropriate cross-linking agent. For example, divinylbenzene, divinylnaphthalene and their derivatives, for example, diethylene glycol carboxylic acid esters such as diethylene glycol methacrylate, triethylene glycol methacrylate, ethylene glycol methacrylate, tetraethylene glycol dimethacrylate, 1,2-propylene glycol, 1,3
-General cross-linking agents such as butanediol can be appropriately used.

Examples of the colorant used for the toner include carbon black, iron black, nigrosine, benzidine yellow, quinacridone, rhodamine B, and phthalocyanine blue. Further, in order to use the toner as a magnetic toner, magnetic powder may be contained. In this case, the magnetic material also serves as a coloring agent. As such magnetic powder,
Materials that are magnetized by being placed in a magnetic field are used, and there are powders of ferromagnetic metals such as iron, cobalt and nickel, or compounds such as magnetite, hematite and ferrite.

As the hydrocarbon compound used as the release agent, paraffin having 20 or more carbon atoms, polyolefin, and the like are preferable, for example, paraffin wax (Nippon Oil), paraffin wax (wax made in Japan), micro wax (Nippon Oil) ), Microcrystalline Wax (Japanese wax), PE
-130 (Hoechst), Mitsui Highwax 110P (Mitsui Petrochemical), Mitsui Highwax 220P (Mitsui Petrochemical), Mitsui Highwax 660P (Mitsui Petrochemical), and the like, and particularly preferably paraffin is used. Hydrogenated polybutadiene is also preferably used.

As a suspension stabilizer during suspension polymerization, a poorly soluble finely powdered inorganic compound (for example, BaSO ₄ , CaSO ₄ , MgCO ₃ , BaCO ₃ , CaCO ₃ , Ca
Insoluble polymers such as ₃ (PO ₄ ) ₂ ; Inorganic polymers such as diatomaceous earth, talc, silicic acid, clay, talc; Powders of metal oxides; Silane coupling agents, Titanium coupling agents, Zircoaluminate couplings Inorganic polymer treated with an agent etc.), water-soluble polymer (eg polyvinyl alcohol,
Gelatin, starch, methylocellulose, ethyl cellulose, carboxymethyl cellulose, polyacrylic acid and salts thereof, alginate) and the like are applicable to the present invention.
These suspension stabilizers are usually used in the range of 0.1 to 10% by weight.

An external additive may be mixed with the toner as needed. Examples of such external additives include lubricants such as Teflon and zinc stearate, fixing aids (such as low molecular weight polyethylene), fluidity imparting agents, anti-caking agents (such as colloidal silica), or conductivity imparting agents. Examples of the agent include metal oxides such as tin oxide.

The developer of the present invention can be applied to various developing methods. For example, a magnetic brush developing method, a cascade developing method, a method using a conductive magnetic toner described in U.S. Pat.No. 3,909,258, a method using a high resistance magnetic toner described in JP-A-53-31136, There are methods described in JP-A-54-42141, JP-A-55-18656, JP-A-54-43027, a fur brush developing method, a powder cloud method, an imprint developing method, and the like.

Hereinafter, the present invention will be described in more detail based on examples.

Example 1 The above mixture was mixed for about 5 minutes while heating to about 60 ° C. in a container equipped with a high shear mixing device such as TK Homomixer (made by Tokushu Kika Kogyo). At this time, the styrene-dimethylaminoethyl methacrylate copolymer was melted in the styrene monomer while being heated to 60 ° C.

Separately, disperse 4 g of Aerozil # 200 in 1000 cc of water and 60 ℃
The above slurry was added to the mixture with heating and stirring with a TK homomixer, and the mixture was stirred at 4000 rpm for about 1 hour. After that, the mixed system was stirred by paddle blade stirring to complete the polymerization. After that, 4% sodium hydroxide based on the weight of the toner was charged into the polymerization reaction tank, and the mixture was stirred for 6 hours at a rotation speed at which particles did not settle while being heated to 40 ° C., and then passed to remove the aqueous medium. Removed.

The obtained polymer particles were heat-treated for about 1 hour while being stirred in a heating oven whose temperature was set to 45 ° C. Silica is added externally to the obtained magnetic toner, and a commercially available high-speed copying machine NP
When an image forming durability was performed using an improved machine of -500 (manufactured by Canon), a clear image without unevenness in the halftone portion due to aggregation was obtained. Further, when the magnetic toner was dissolved in methyl ethyl ketone and the amount of residual styrene monomer was measured by gas chromatography, almost no detection was found.

Example 2 Polymer particles prepared in the same manner as in Example 1 were heated to 65 ° C. at about 30 ° C.
Heat treatment was performed for a minute. The heat-treated magnetic toner (polymer particles) gave good development results similar to those in Example 1.

Comparative Example In the same manner as in Example 1, polymer particles were obtained,
After air-drying at room temperature (about 20 ° C.), silica was externally added in the same manner as in Example 1 to perform image development and durability.
As compared with the magnetic toner of No. 3, unevenness in the halftone portion was more likely to occur due to agglomeration, and the image was also fogged and unsharp with a greasiness.

When the residual styrene monomer of this toner was measured in the same manner as in Example 1, a significantly higher peak value than that in Example 1 was confirmed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Hyoda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Eiichi Imai 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non-Co., Ltd. (56) Reference JP-A-56-70556 (JP, A)

Claims (1)

[Claims] 1. A suspension-polymerized toner formed of polymer particles containing a colorant obtained by separating from an aqueous medium after the suspension-polymerization step is heated at a temperature of 35 ° C. to 75 ° C. for 30 minutes or more. The method for producing a suspension-polymerized toner, wherein the residual monomer remaining in the polymer particles is removed.