JP3628433B2 - Method for producing toner for developing electrostatic charge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner manufacturing method for developing an electrostatic image in electrophotography, electrostatic recording, and the like.
[0002]
[Prior art]
The electrophotographic toner used in the dry development method is usually produced by melt-kneading a thermoplastic resin and a colorant, and then pulverizing, and classifying the obtained granular material. However, this method requires a lot of equipment and has a problem of consuming a lot of power. In particular, in recent years, due to the demand for higher image quality of images obtained by copying, toners with a narrow particle size distribution and toners with a small particle size have been required. It is difficult to produce a toner having a small diameter.
In order to solve these problems, a toner production method using a suspension polymerization method has been proposed. However, the production of dry toner by the suspension polymerization method has the following problems.
First, it is difficult to adjust the particle size within a desired range in a granulation process in which a liquid monomer composition is made into particles in a dispersion medium in the production of a toner by an ordinary suspension polymerization method. That is the point. The second is that the produced polymer particles have a wide particle size distribution, and a classification operation is required to obtain particles having an appropriate particle size range.
There have been various proposals for solving the above problems of the suspension polymerization method. For example, Japanese Patent Application Laid-Open No. 59-161 proposes a method using incompletely saponified polyvinyl alcohol as a dispersion stabilizer, but the dispersibility is certainly superior to the case of using ordinary polyvinyl alcohol. The particle size distribution of things is wide. JP-A-62-203167, JP-A-62-299862, JP-A-63-113561, and JP-A-63-165869 disclose suspension polymerization by discharging under pressure by using a powder dispersant. In Japanese Patent Application Laid-Open No. 58-173754, a method of making a polymer fine particles using a rotating disk atomizer, and in Japanese Patent Application Laid-Open No. 59-26128, a dispersion medium and a dispersion liquid are caused to flow between an inner cylinder and an outer cylinder, A method for producing fine particles by applying a shearing force has been proposed. Japanese Laid-Open Patent Publication No. 63-112602 proposes a method of irradiating ultrasonic waves. However, in any of these methods, it has been difficult to obtain a toner having both a reduction in the particle size of the polymer and a narrow particle size distribution of the polymer.
As a method for solving these problems, JP-A-3-95564 has invented a method in which a monomer composition containing a polymerizable monomer is passed through a porous glass having pores and then subjected to suspension polymerization. . In this method, a narrow particle size distribution is surely obtained. However, when a toner having a small particle size of about 4 μm to 6 μm is prepared, the dispersed pigment or charge control agent is finely divided in the porous glass. The holes are clogged and need to be washed frequently, which has been a problem in industrialization.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for efficiently producing a toner having a small particle size and a narrow particle size distribution in a method for producing a toner for developing an electrostatic image by suspension polymerization.
[0004]
[Means for Solving the Problems]
As a result of repeated studies to solve the above problems, the present inventors have completed the present invention. That is, according to the present invention, the polymerizable monomer and the colorant are dispersed and mixed, the obtained composition is dispersed in a hydrophilic organic solvent, passed through a porous glass having pores, and then dispersed. A step of producing an emulsion of a polymerizable monomer in an aqueous solvent in which a stabilizer is present, and following this step, suspension of the emulsion composed of the polymerizable monomer to produce toner particles for electrostatic charge development. And a method for producing a toner for developing an electrostatic charge, comprising a polymerization step.
[0005]
[Means for Solving the Problems]
A polymerizable monomer is used as a raw material for the electrostatic charge developing toner produced in the present invention. This polymerizable monomer is a monomer having a vinyl group. Specifically, styrene, parachlorostyrene, vinyl toluene, vinyl chloride, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate , 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-chloroethyl acrylate, acrylonitrile, acrylamide, acrylic acid, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, methacrylic acid Methyl, ethyl methacrylate, propyl methacrylate, methacrylate-n-butyl, isobutyl methacrylate, dodecyl methacrylate, -2-ethylhexyl methacrylate, methacrylic acid Lyl, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-chloroethyl methacrylate, methacrylonitrile, methacrylamide, methacrylic acid, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyl methyl ether, vinyl ethyl ether, vinyl Monomers such as isobutyl ether, vinyl methyl ketone, N-vinyl pyrrolidone, N-vinyl pyridine and butadiene can be used alone or in combination of two or more. A crosslinkable polymerizable monomer can also be present in the polymerizable monomer.
[0006]
Various pigments are used as the colorant of the electrostatic charge developing toner of the present invention. Examples of pigments include black pigments, yellow pigments, orange pigments, red pigments, purple pigments, and green pigments.
Examples of black pigments include carbon black (oil furnace black, channel black, lamp black, acetylene black, etc.), azine dyes such as aniline black, metal salt azo dyes, metal oxides, composite metal oxides, etc. Can do.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake. be able to. Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK and the like.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B Can do.
Examples of purple pigments include Fast Violet B and Methyl Violet Lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of the green pigment include chrome green, chromium oxide, pigment green B, and malachite green lake.
These pigments can be used alone or in combination of two or more.
The amount of these colorants used is preferably about 1% to 10% with respect to the polymerizable monomer.
[0007]
In order to control charging of the electrostatic charge developing toner of the present invention, a charge control agent is used. Specifically, nigrosine, an azine-based dye (Japanese Examined Patent Publication No. 42-1627) containing an allyl group having 2 to 16 carbon atoms, a basic dye (for example, CI Basic Yellow 2 (CI. 41000)) CI Basic Yellow 3, CI Basic Red 1 (CI 45160), CI Basic Red 9 (CI 42500), CI Basic Violet 1 (CI 42535) ), CI Basic Violet 3 (C.I. 42555), C.I.Basic Violet 10 (C.I.45170), C.I.Basic Violet 14 (C.I. 42510), C.I. Basic Blue 1 (CI 42025), CI Basic Blue 3 (CI 51005), CI Basic Blue 5 (C.I. 42140), C.I.Basic Blue 7 (C.I.42595), C.I.Basic Blue 9 (C.I.52015), C.I.Basic Blue 24 (C.I. I.52030), C.I.Basic Blue 25 (C.I.52025), C.I.Basic Blue 26 (C.I.44045), C.I.Basic Green 1 (C.I.42040), Lake pigments of these basic dyes, such as CI Basic Green 4 (CI 42000), CI Solvent Black 8 (CI 26150), benzoylmethyl-hexadecyl ammonium chloride, decyltrimethyl Quaternary ammonium salts such as chloride, or dialkyl such as dibutyl or dioctyl Compound, dialkyltin borate compound, guanidine derivative, vinyl polymer containing amino group, polyamine resin such as condensation polymer containing amino group, JP-B-41-20153, 43-27596, 44-6397 No. 45-26478, metal complexes of monoazo dyes, salicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid Zn described in JP-B-55-42752, JP-B-59-7385, Examples thereof include metal complexes such as Al, Co, Cr, and Fe, sulfonated copper phthalocyanine pigments, and fluorine-based compounds described in JP-A-4-151168.
The charge control agent for these electrostatic developing toners is preferably used in the toner in an amount of about 1 wt% to 20 wt%, preferably about 3 wt% to 10 wt%.
[0008]
The method of the present invention comprises a step of treating a polymerizable monomer to produce an emulsion of the polymerizable monomer and a step of producing a toner by polymerizing the emulsion of the polymerizable monomer.
In the step of producing an emulsion of a polymerizable monomer, first, a polymerizable monomer, a colorant and a charge control agent are dispersed and mixed, and the resulting composition is dispersed in a hydrophilic organic solvent. Any hydrophilic organic solvent may be used as long as it is soluble in water. For example, methyl alcohol, ethyl alcohol, propyl alcohol, ethylene glycol, methyl ethyl sorb, acetone and the like can be used. The concentration of the polymerizable monomer in the hydrophilic organic solvent is 10% by weight to 80% by weight, preferably 30% by weight to 70% by weight. If the concentration of the organic solvent is less than 10% by weight, it is necessary to use a porous glass having a small pore size in order to obtain a desired particle size, so that pigment particles and the like are easily clogged, while 80% by weight. If it exceeds%, the particle size distribution becomes wide, which is not preferable. A homogeneous solution comprising a polymerizable monomer, a colorant, a charge control agent, and a hydrophilic organic solvent obtained in this manner is prepared from a porous glass having a pore size of 0.2 μm or more and 5 μm or less, preferably 1 μm to 3 μm. When passing through, the hydrophilic organic solvent is eluted into the dispersion medium, and an emulsion having a small particle size mainly composed of a monomer and a colorant can be obtained. In this case, if the pore size of the porous glass is less than 1 μm, clogging occurs. On the other hand, when the pore size of the porous glass exceeds 3 μm, it is necessary to use a large amount of a hydrophilic solvent in order to obtain a desired particle size, which is inefficient.
[0009]
The porous glass having pores used in the present invention is a glass having pores adjusted to a narrow range, and has a chemical composition mainly composed of silicic acid, boric acid and alumina. This glass is called microporous glass (MPG) or shirasu porous glass (SPG), and boric acid and alkali which are easily soluble in acid when heat-treated at several hundred degrees Celsius on glass containing silicic acid, boric acid, alumina, alkali, etc. This is a porous glass obtained by treating a phase-separated glass with an acid and washing away boric acid and alkali by utilizing the property of separating into a phase consisting of the above and other phases.
In order to perform the granulation of the present invention using the porous glass having pores, a porous glass having a tubular or plate shape is preferable. The size of the oil droplets and the particle size of the toner obtained depend on the concentration and viscosity of the composition. The pore diameter of the glass used for producing the toner of the present invention is preferably 1 μm to 5 μm.
[0010]
In order to improve the dispersibility of the colorant, the charge control agent, etc., and to adjust the thermal characteristics of the toner, a thermoplastic resin can be added to the polymerizable monomer. It can also be added in a hydrophilic organic solvent. As the thermoplastic resin, in addition to the polymerized polymerizable monomer described above, polyester, polyurethane, polyamide, epoxy resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic A group petroleum resin can be used alone or in combination. The ratio of addition is 1% to 30% by weight, preferably 5% to 20% by weight, based on the polymerizable monomer.
[0011]
In order to improve the fixing property, anti-offset property, and prevention of paper wrapping in the heat roller fixing of toner particles for electrostatic charge development, it is preferable to add a releasable substance to the toner particles. Specific examples of the releasable substance include low molecular weight polyolefins such as low molecular weight polyethylene, low molecular weight polypropylene, and oxidized polyethylene, natural waxes such as beeswax, carnauba wax, and montan wax, stearic acid, palmitic acid, and the like. Examples include higher fatty acids such as myristic acid, metal salts of higher fatty acids, higher fatty acid amides, and the like. These can be used alone or in combination of two or more. Among these compounds, low molecular weight polypropylene and carnauba wax are preferable. The amount of these release agents used is about 0.5% to 5.0% by weight with respect to the polymerizable monomer. Specific methods for adding the toner particles include a method of adding them to the polymerizable monomer, a method of fixing the release agent to the surface of the polymer particles by a mechanical impact force, and a thermoplastic resin and a colorant. Examples thereof include a method of wet-adhering and coating the surface of the powder particles as a component using an emulsion of a release agent.
[0012]
A solution prepared by dissolving a dispersion in which a polymerizable monomer, a colorant, and a charge control agent are dispersed and mixed in a hydrophilic organic solvent is passed through a porous glass, and then in an aqueous solvent in which a dispersion stabilizer is present. To supply.
Examples of the dispersion stabilizer include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and salts thereof, starch, gum alginate, and casein.
The concentration of the dispersion stabilizer is about 0.1% to 5% by weight.
The emulsion of the polymerizable monomer which exists in an aqueous solvent can be obtained by the above process.
[0013]
The monomer composition granulated as described above is heated and stirred to effect suspension polymerization of the polymerizable monomer emulsion. Usually, the polymerization treatment is performed at a temperature of 50 to 100 ° C. for 8 to 48 hours.
[0014]
In the monomer composition, suspension polymerization may be carried out in the presence of the following crosslinking agent in order to form a crosslinked polymer.
Examples of the crosslinking agent include divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol acrylate, triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexaglycol dimethacrylate, neopentyl glycol dimethacrylate, Dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, 2,2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane tri Methacrylate, trimethylolpropane triacrylate, tetramethylol methane tetraacrylate, dibromoneopentyl glycol dimethacrylate Can be used over preparative, a general crosslinking agent such as diallyl phthalate appropriate.
If the amount of these cross-linking agents used is too large, the toner will be difficult to melt with heat and the fixability will be poor. Also, if the amount of the crosslinking agent used is too small, properties such as blocking resistance and durability required for the toner will deteriorate, and part of the toner will adhere to the roller surface and transfer to the next paper in hot roll fixing. This makes it difficult to prevent the offset phenomenon. Therefore, the use amount of these crosslinking agents is 0.05 to 10 parts, preferably 0.1 to 10 parts, based on 100 parts of the polymerizable monomer.
[0015]
In the present invention, the polymerization initiator may be added to the dispersion containing the monomer composition after granulation, but from the point of imparting a uniform polymerization initiator to each monomer composition particle. It is preferable to be contained in the monomer composition before granulation.
Examples of such polymerization initiators include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbohydrate). Nitrile), 2,2′-azobis-4-methoxy-2,4-dimethylpareronitrile, other azobisisobutyronitrile (AIBN) or azo-based polymerization initiators; benzoyl peroxide, methyl ethyl ketone Examples thereof include peroxide polymerization initiators such as peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorolylbenzoyl peroxide, and lauroyl peroxide.
Alternatively, suspension polymerization may be performed in the monomer composition in the presence of a polymer dissolved in the polymerizable monomer.
In this case, in addition to obtaining a polymerized toner that is preferable in terms of electrical characteristics and thermal characteristics depending on the characteristics of the polymer, it also functions to adjust the viscosity of the monomer composition.
[0016]
After completion of the polymerization reaction, post-treatment is performed by a conventional method to obtain polymerized toner particles. For example, the produced polymerizable particles are washed, the dispersion stabilizer is removed, and then collected by an appropriate method such as filtration, decantation, and centrifugal separation, and dried to obtain a polymerized toner.
[0017]
【Example】
Hereinafter, the present invention will be described specifically by way of examples. In addition, the part which is the quantity of each component described in each Example is a weight part.
[0018]
[Example-1]
A mixture of 60 parts of styrene, 40 parts of n-butyl methacrylate, 5 parts of a metal complex dye (manufactured by Orient Chemical; S-34) and 5 parts of carbon black was dispersed and mixed for 8 hours using a ball mill to prepare a composition. 100 parts of this composition was diluted with 200 parts of methanol, and 2 parts of azobisisobutylnitrile was added and dissolved. A porous glass tube having a pore size of 3.6 μm, 10 μm × 10 mm, previously immersed in ion-exchanged water, is circulated with a 2% polyvinyl alcohol aqueous solution inside the tube using a pump, and from the outside of the porous glass tube. The monomer composition was pressurized and passed through a porous glass tube, and sent into a polyvinyl alcohol aqueous solution to prepare an emulsion.
The obtained emulsion was transferred to a four-necked flask equipped with a stirrer, a thermometer, and an inert gas introduction tube, and polymerized at 70 ° C. for 5 hours. Thereafter, the mixture was cooled to room temperature, transferred to a stainless steel container, centrifuged at 2000 RPM for 15 minutes, the supernatant was removed, 100 parts of water was added, and the mixture was stirred well, and centrifuged under the above conditions. After removing the supernatant, 100 parts of water was again added and stirred well, filtered and dried to obtain a toner. When the particle diameter of this toner was measured with a Coulter counter, the average particle diameter was 5.8 μm, and 5.8 μm ± 0.5 μm particles were 95%, indicating a very narrow particle size distribution.
To 100 parts of the powder particles, 0.3 part of colloidal silica was added and mixed to obtain a toner, and 3 parts of the toner was mixed with 100 parts of an iron powder carrier to prepare a two-component developer. This developer is put into a magnetic brush developing device, an electrostatic latent image formed by an ordinary electrophotographic method is developed on an organic photoreceptor, and this is transferred to a plain paper while applying corona discharge to produce a clear black color. I got an image.
[0019]
Example-2
A composition of 60 parts of styrene, 40 parts of methyl acrylate, 10 parts of polyester resin, 5 parts of 3,5-ditertiary butylsalicylic acid and 5 parts of copper phthalocyanine pigment was dispersed and mixed for 8 hours using a ball mill, 100 parts of this composition was diluted with 100 parts of ethyl alcohol, and 2 parts of azobisisobutylnitrile was added and dissolved. Using a porous glass tube having a pore size of 2.8 μm and 10 mm × 10 mm which has been preliminarily immersed in ion-exchanged water, a 2% polyvinyl alcohol aqueous solution is circulated inside the tube by a pump, and the above is performed from the outside of the porous glass tube. The monomer composition was pressurized, passed through a porous glass tube, and sent into an aqueous polyvinyl alcohol solution to prepare an emulsion.
The obtained emulsion was transferred to a four-necked flask equipped with a stirrer, a thermometer, and an inert gas introduction tube, and polymerized at 70 ° C. for 5 hours. Thereafter, the mixture was cooled to room temperature, transferred to a stainless steel container, centrifuged at 2000 RPM for 15 minutes, the supernatant was removed, 100 parts of water was added, and the mixture was stirred well, and centrifuged under the above conditions. After removing the supernatant, 100 parts of water was again added and stirred well, filtered and dried to obtain a toner. When the particle diameter of the toner was measured with a Coulter counter, the average particle diameter was 5.2 μm, and the particle size distribution of the particles of 5.2 μm ± 0.5 μm was 95%, and the particle size distribution was in a very narrow range.
To 100 parts of the powder particles, 0.3 part of colloidal silica was added and mixed to obtain a toner, and 3 parts of the toner was mixed with 100 parts of an iron powder carrier to prepare a two-component developer. This developer is put in a magnetic brush developing device, an electrostatic latent image formed by an ordinary electrophotographic method is developed on an organic photoreceptor, and this is transferred while applying corona discharge to plain paper. A cyan image was obtained.
[0020]
Example-3
A mixture of 60 parts of styrene, 40 parts of n-butyl methacrylate, 10 parts of polystyrene, 5 parts of metal complex dye (manufactured by Orient Chemical Co., Ltd .; S-34) and 5 parts of carbon black was pulverized and mixed for 8 hours with a ball mill to obtain a uniform composition. 100 parts of this composition was diluted with 200 parts of methanol, and 2 parts of azobisisobutylnitrile was added and dissolved. A porous glass tube having a pore size of 2 μm, 10 μm × 10 mm, which is preliminarily immersed in ion-exchanged water, is circulated with a 2% polyvinyl alcohol aqueous solution using a pump inside the tube. The mass composition was pressurized, passed through a porous glass tube, and sent into an aqueous polyvinyl alcohol solution to form an emulsion.
The obtained emulsion was transferred to a four-necked flask equipped with a stirrer, a thermometer, and an inert gas introduction tube, and polymerized at 70 ° C. for 5 hours. Thereafter, it was cooled to room temperature, transferred to a stainless steel container, centrifuged at 2000 RPM for 15 minutes, the supernatant was removed, 100 parts of water was added, and the mixture was well stirred and centrifuged under the above conditions. After removing the supernatant, 100 parts of water was again added and stirred well, filtered and dried to obtain a toner. When the particle diameter of this toner was measured with a Coulter counter, the average particle diameter was 4.8 μm, and the particles of 4.8 μm ± 0.5 μm were 95%, indicating a very narrow particle size distribution.
To 100 parts of the powder particles, 0.3 part of colloidal silica was added and mixed to obtain a toner, and 3 parts of the toner was mixed with 100 parts of an iron powder carrier to prepare a two-component developer. This developer is put into a magnetic brush developing device, an electrostatic latent image formed by an ordinary electrophotographic method is developed on an organic photoreceptor, and this is transferred to a plain paper while applying corona discharge to produce a clear black color. I got an image.
[0021]
Example-4
The same treatment as in Example 3 was performed to obtain a black powder having a sharp particle size distribution of 4.6 μm. 100 parts of this black powder is dispersed in 40 parts of a water-methanol mixed solvent (mixing ratio 1: 1), 2 parts of carnauba wax emulsion (solid content 50%, average particle size 0.15 μm) is added, and black powder is added. A carnauba wax layer was formed on the surface. Next, a toner was prepared in the same manner as in Example 3 to prepare a developer. This developer is put into a magnetic brush developing device, an electrostatic latent image formed by an ordinary electrophotographic method is developed on an organic photoconductor, transferred while applying corona discharge to plain paper, and silicone oil is supplied. When the image was heat-fixed with a fixing roller that did not, no paper wrapping or offset phenomenon occurred within a fixing temperature range of 150 to 210 ° C., and a clear black image could be obtained.
[0022]
【The invention's effect】
According to the present invention, an operation such as classification is not required, a toner having a uniform particle diameter can be easily produced, the toner particle diameter can be easily adjusted, and a small particle diameter toner can be obtained efficiently. it can.

Claims (4)

A composition obtained by dispersing and mixing a polymerizable monomer and a colorant is dispersed in a hydrophilic organic solvent, passed through a porous glass having pores, and then an aqueous solution containing a dispersion stabilizer. A process for producing an emulsion of a polymerizable monomer in a solvent, and subsequently to this process, an emulsion composed of a polymerizable monomer is subjected to suspension polymerization to produce electrostatic charge developing toner particles composed of suspension polymerized particles. A method for producing a toner for developing an electrostatic charge, comprising: a polymerization step for producing the toner. The method for producing a toner for developing an electrostatic charge according to claim 1, wherein a thermoplastic resin is present in the polymerizable monomer or the hydrophilic organic solvent. The method for producing a toner for electrostatic charge development according to claim 1, wherein the pore diameter of the porous glass having pores is 1 μm to 3 μm. 2. A method for producing an electrostatic charge developing toner comprising producing electrostatic charge developing toner particles having a release agent layer adhered to the surface of the suspension polymerized particles according to claim 1.