KR20140115634A - Process for preparing polymerized toner - Google Patents
Process for preparing polymerized toner Download PDFInfo
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- KR20140115634A KR20140115634A KR1020130030425A KR20130030425A KR20140115634A KR 20140115634 A KR20140115634 A KR 20140115634A KR 1020130030425 A KR1020130030425 A KR 1020130030425A KR 20130030425 A KR20130030425 A KR 20130030425A KR 20140115634 A KR20140115634 A KR 20140115634A
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/087—Binders for toner particles
- G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- G03G9/08735—Polymers of unsaturated cyclic compounds having no unsaturated aliphatic groups in a side-chain, e.g. coumarone-indene resins
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Abstract
Description
The present invention relates to a method for producing a polymerized toner. More particularly, the present invention relates to a method for producing a polymerized toner capable of achieving a narrow particle diameter distribution, a high transfer efficiency, and a uniform image by using calcium phosphate as an aqueous dispersion stabilizer during suspension polymerization and using a polymeric charge control agent having a predetermined structural formula .
Toner is used for electrophotographic development, electrostatic printer, copying machine, and the like, and refers to a paint capable of forming a desired pattern by being transferred and fixed on an object to be transferred. [0002] Recently, with the generalization of document creation using a computer and the like, the demand for an image forming apparatus such as a printer is rapidly increasing, and accordingly, the amount of toner used is also increasing.
Generally, as a method for producing toner, there are a manufacturing method using pulverization and a manufacturing method using polymerization. The most widely known manufacturing method using pulverization is a method in which a resin and a pigment are put together through a melt-mixing process and then melt-mixed or extruded, followed by pulverization and classification to produce toner particles. However, the toner particles produced by this process have a problem that the chargeability and the flowability are poor because the toner particles have a wide distribution of particle diameters and have a very irregular shape, such as having sharp corners.
To solve this problem, a method of producing spherical toner particles by a polymerization method has been proposed. The emulsion polymerization method (agglomeration method) and the suspension polymerization method are known as the method of producing the toner by the polymerization method. Since the emulsion polymerization method has difficulties in controlling the particle size distribution and the quality reproducibility of the produced toner, A toner manufacturing method by polymerization is more preferred.
However, the toner prepared by the suspension polymerization is subjected to a process of dispersing and polymerizing the monomer mixture in the form of a droplet through a homogenization process with the aqueous dispersion. In this process, it is difficult to produce particles having a narrow particle size distribution. In addition, toner particles produced through such a suspension polymerization process have a very uniform chargeability, so that a uniform image can be realized with high transfer efficiency.
An object of the present invention is to provide a method for producing a polymerized toner capable of effectively producing a toner having a narrow particle size distribution, and particularly capable of realizing a high transfer efficiency and a uniform image.
In order to accomplish the above object, the present invention provides a method for manufacturing a magnetic recording medium comprising the steps of: forming an aqueous dispersion medium containing calcium phosphate; Forming a monomer mixture comprising a charge control agent, a pigment, and a binder resin monomer having a weight average molecular weight of 10,000 to 20,000 g / mol represented by the following formula (1); Dispersing the monomer mixture in the form of droplets in the aqueous dispersion medium; And suspension polymerization of the monomer mixture dispersed in the droplet form, wherein the calcium phosphate is used in an amount of 2 to 6 parts by weight based on 100 parts by weight of the monomer mixture, and polymerization using 0.6 to 10 parts by weight of the charge control agent A method for producing a toner is provided.
[Chemical Formula 1]
In Formula 1,
R is a branched or straight-chain alkyl group having 10 to 30 carbon atoms,
l, m and n are the same as or different from each other and each is an integer of 1 to 40, and l: (m + n) is 3:97 to 15:85.
The present invention also provides a polymerized toner produced by the above method.
The present invention can effectively produce a toner having a narrow particle size distribution by carrying out a suspension polymerization reaction using calcium phosphate and a charge control agent as an aqueous dispersion stabilizer in an optimum amount range, respectively.
Particularly, the polymerized toner produced according to the present invention is characterized in that it is easy to control the toner particle size distribution with a narrow particle diameter distribution and the reproducibility of the quality of the produced toner is very easy. In addition, the polymerized toner can achieve a high transfer efficiency and a uniform image, and can exert excellent performance in electrophotographic development and the like.
In the present invention, the terms first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.
Moreover, the terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprising," "comprising," or "having ", and the like are intended to specify the presence of stated features, But do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.
Also in the present invention, when referring to each layer or element being "on" or "on" each layer or element, it is meant that each layer or element is formed directly on each layer or element, Layer or element may be additionally formed between each layer, the object, and the substrate.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Hereinafter, a method of producing a polymerized toner according to a specific embodiment of the present invention will be described.
The present inventors have found that dispersion stability and suspension polymerization stability are ensured by using calcium phosphate as an aqueous dispersion stabilizer in the production of toner by suspension polymerization, using a specific polymer compound as a charge control agent, and optimizing each of them in a specific content range The present inventors have found that the particle size can be easily controlled and the narrow particle size distribution can be controlled.
According to one embodiment of the present invention, the present invention can be applied to a suspension polymerization method of a general polymerized toner, wherein calcium phosphate is used as a dispersion stabilizer in the preparation of an aqueous dispersion medium, and as a charge control agent, A polymer having a molecular weight of 10,000 to 20,000 g / mol can be used.
[Chemical Formula 1]
In Formula 1,
R is a branched or straight-chain alkyl group having 10 to 30 carbon atoms,
l, m and n are the same as or different from each other and each is an integer of 1 to 40, and l: (m + n) is 3:97 to 15:85.
Generally, in the suspension polymerization method, a monomer mixture in which a pigment, a charge control agent, a wax or the like is dissolved or dispersed in a monomer for a binder resin is prepared, and the mixture is dispersed in an aqueous dispersion medium with a stirrer to form fine droplet particles of the monomer mixture. Followed by suspension polymerization to obtain a toner having a desired particle diameter.
The present invention is based on the finding that excellent dispersion stability is ensured by using calcium phosphate as a dispersion stabilizer of an aqueous dispersion medium in the suspension polymerization method and excellent compatibility with a binder resin is obtained by using a polymer of a specific structural formula as a charge control agent, And controlling the particle diameter of the toner particles effectively to produce a polymerized toner having a narrow particle size distribution.
The present invention relates to a process for forming a monomer mixture comprising a charge controlling agent, a pigment and a monomer for a binder resin represented by the general formula (1) and having a weight average molecular weight of 10,000 to 20,000 g / mol, Dispersing the monomer mixture in the form of droplets in the aqueous dispersion medium, and suspending and polymerizing the monomer mixture dispersed in the droplet form, wherein the calcium phosphate is added to the monomer mixture in an amount of from 2 to 100 parts by weight per 100 parts by weight of the monomer mixture, And 6 to 10 parts by weight of the charge control agent are used.
According to such a production method, a monomer mixture containing a monomer for a binder resin, a charge control agent, and a pigment is added to an aqueous dispersion medium containing calcium phosphate to disperse the dispersion in a fine droplet form, and then the dispersion is subjected to suspension polymerization. When such polymerization proceeds, the polymerization is carried out in the monomer mixture in the form of fine droplets to form toner particles, and the desired polymerized toner in the present invention can be produced.
Particularly, according to one embodiment of the present invention, calcium phosphate is optimally used as a dispersion stabilizer in an amount of about 2 to about 6 parts by weight based on 100 parts by weight of the monomer mixture, and simultaneously, as a charge control agent, Is used in an optimal range of about 0.6 to about 10 parts by weight based on 100 parts by weight of the monomer mixture to provide a uniform particle size distribution with a narrow particle size distribution and a high transfer efficiency and uniform image realization do.
The manufacturing method of the toner will be described below.
In the production method of the present invention, first, an aqueous dispersion medium containing calcium phosphate is formed, and a polymer charge control agent, a pigment, and a monomer for a binder resin represented by Formula 1 and having a weight average molecular weight of 10,000 to 20,000 g / After the monomer mixture is formed, the monomer mixture is added to the aqueous dispersion medium and dispersed in the form of a droplet. At this time, the aqueous dispersion medium for dispersing the monomer mixture can be obtained by dissolving the dispersion stabilizer in water. In the present invention, the monomer mixture can be maintained in a stable dispersion state in the aqueous medium by using calcium phosphate as the dispersion stabilizer .
As described above, calcium phosphate used in the present invention has a role as a dispersion stabilizer for a polymerizable monomer composition in an aqueous dispersion medium.
As a material used as a dispersion stabilizer, inorganic stabilizers such as calcium phosphate, hydroxyapatite, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, Calcium silicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic dispersion stabilizer include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxy propyl cellulose, ethyl cellulose, carboxymethyl cellulose ( carboxyl methyl cellulose and its sodium salt, polyacrylic acid and salts thereof, and starch.
In the toner manufacturing method through the suspension polymerization process, such a dispersion stabilizer is dispersed in water and used. These dispersion stabilizers seem to stabilize the water droplets by uniformly dispersing them in an aqueous medium, preventing aggregation between the polymerizable monomer composition particles present as droplets, and adsorbing them uniformly on the surface of these droplets. Further, such a dispersion stabilizer is solubilized after completion of the polymerization reaction of the polymerizable monomer in water droplets through acid, alkali treatment, hot water washing or the like, and is separated from the toner particles.
However, in such a compound that can be used as a dispersion stabilizer, it is often difficult to completely remove the compound from the toner particle surface depending on physical properties such as its solubility, molecular weight, viscosity and the like. Further, depending on the composition of the toner particles, a part of the colorant and the charge control agent may be decomposed or eluted or heat denaturation may occur due to a process such as a strong alkali treatment or hot water washing. Therefore, the surface properties of the toner particles, And the like may be damaged, and the developing characteristics and the like of the toner may be remarkably lowered. On the other hand, since the coagulation action is strong in the above-mentioned inorganic dispersion stabilizer, change in viscosity during polymerization reaction of water droplets occurs and the stability as water droplets is lowered, thereby promoting unstable phenomenon such as flocculation of water droplets. I do not.
Accordingly, in the present invention, by using calcium phosphate as an aqueous dispersion stabilizer, it is possible to easily remove the toner particles from the surface of toner particles only by acid treatment and / or water washing without generating such unstable phenomenon, Can be provided. Particularly, since it can be effectively removed even by acid treatment and washing, decomposition and dissolution of a colorant, a charge control agent, and the like do not occur and the thermal deformation does not need to be considered.
In the present invention, calcium phosphate refers to at least one selected from calcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, hydroxy apatite, and mixtures thereof. The size of the crystals, the particle size of the crystal aggregates, Hydroxyapatite and calcium phosphate are preferable, and hydroxyapatite is the most preferable among them, considering the effect of solubility in acid and the like.
In one preferred embodiment of the present invention, the calcium phosphate can be used by producing calcium phosphate in an aqueous medium from a phosphate aqueous solution and a calcium salt aqueous solution. In the case where calcium phosphate is produced from the aqueous medium and used, it is possible to obtain a more favorable effect as a dispersion stabilizer and to obtain a stable suspension state because uniform particle crystals are obtained without generation of agglomerates. Particularly, when powdery calcium phosphate is used as it is, since it tends to be a strong aggregate as a powder, it may be difficult to disperse it in an aqueous medium because the particle size is uneven as an aggregate, and calcium phosphate is produced in an aqueous medium Is more preferable.
When calcium phosphate is produced and used in an aqueous medium as described above, an aqueous solution of sodium phosphate is preferable as a phosphate aqueous solution, and an aqueous solution of calcium chloride is preferable as an aqueous solution of calcium salt. It is more preferred that the aqueous sodium phosphate solution has a pH of about 4 to about 7, preferably about 4.2 to about 6.5, more preferably about 4.5 to about 5.5. In particular, in order to obtain a spherical toner, it is more preferable that the pH of the aqueous solution obtained by mixing the phosphate aqueous solution and the calcium salt aqueous solution is adjusted to about 4.5 to about 5.5.
Thus, in the toner manufacturing method of the present invention, an acid such as hydrochloric acid, nitric acid, sulfuric acid, or the like is dropped into the phosphate aqueous solution, and then an aqueous calcium salt solution is added to adjust the pH of the aqueous dispersion medium to about 4 to about 7, To about 6.5, and more preferably from about 4.5 to about 5.5.
Such calcium phosphate is used in an amount of about 2 to 6 parts by weight, preferably about 2.5 to about 5 parts by weight, more preferably about 2.5 to about 4 parts by weight based on 100 parts by weight of the monomer for binder resin. At this time, the calcium phosphate is preferably used in an amount of about 2 parts by weight or more from the viewpoint of stably retaining the particles during the polymerization reaction, and from about 6 parts by weight or less in terms of preventing generation of small particles in homogenizing the monomer mixture .
When the polymerized toner is prepared using the calcium phosphate aqueous dispersion medium as described above, the resulting toner particles are in a state of adsorbing calcium phosphate on the surface as they are, so that the pH of the aqueous dispersion containing the produced toner particles is about 2 Or less, preferably about 1.7 or less, more preferably about 1.5 or less. After the calcium phosphate is completely dissolved, the toner particles can be recovered. Such a washing process is repeated and dried to obtain the final toner particles have.
As described above, when calcium phosphate is used as the aqueous dispersing agent, the pH of the aqueous dispersion can be easily adjusted to neutral or acid, so that a force capable of moving to the toner particle surface by the electrostatic attraction of the charge control agent having negative charge is provided can do. When the amount of calcium phosphate is less than about 2 parts by weight based on 100 parts by weight of the monomer mixture, the amount of calcium phosphate necessary for stabilizing the monomer mixture droplets is less than that required for the stabilization of the monomer mixture droplets, If more than about 6 parts by weight are used per 100 parts by weight of the mixture, small particles may be produced during homogenization of the monomer mixture.
Here, the solubility in the pH of calcium phosphate is drastically solubilized in the acidic region at low pH with the pH range of about 1.5 to about 2.5 as the boundary region, and is 100% solubilized in the strongly acidic region of pH 1.5 or less, To completely remove the dispersion stabilizer particles, the acid treatment may be carried out at a pH of about 2.0 or less, preferably about 1.7 or less, more preferably about 1.5 or less. Unlike the alkali treatment process, this acid treatment process is preferable because other components such as colorant, charge control agent and the like in the toner composition are not decomposed, dissolved and denatured, and do not have any influence on the toner characteristics.
In addition, the present invention is characterized by using an aqueous dispersion medium containing calcium phosphate as described above and a polymer having a weight average molecular weight of 10,000 to 20,000 g / mol represented by the following formula (1) as a charge control agent.
[Chemical Formula 1]
In Formula 1,
R is a branched or straight-chain alkyl group having 10 to 30 carbon atoms,
l, m and n are the same as or different from each other and each is an integer of 1 to 40, and l: (m + n) is 3:97 to 15:85.
According to an embodiment of the present invention, l, m and n may each be an integer of 1 to 40, preferably 3 to 35, more preferably 5 to 30, and l: (m + n) 97 to 15:85, preferably 5:95 to 17:83, and more preferably 7:93 to 20:80.
The above l, m and n can be inversely estimated from the Tg value and the molecular weight.
The charge control agent represented by Formula 1 is a styrene-acrylic polymer containing a sulfonic acid group. At this time, when the charge control agent having the structure of the polymer copolymer including the sulfonic acid group is used, the effect of the charging phenomenon by the pigment is effectively removed by effectively removing the surface concentration of the pigment and deterioration of the charge control property by adsorption The polymerized toner produced by the improvement and homogeneity of the charging property can be further imparted with a feature of achieving a uniform image with a high transfer efficiency while having a narrow particle size distribution.
It is generally known that charge control agents include cationic charge control agents, anionic charge control agents, and mixtures thereof. Examples of cationic charge control agents include nigrosine electron donor dyes, higher aliphatic metal salts, alkoxy amines, chelates, quaternary ammonium salts, alkyl amides, fluorine treatment activators, and metal salts of naphthalic acid. Examples of anionic charge control agents include electron donor organic complexes, chlorinated paraffins, chlorinated polyesters, polyesters containing excess acid, sulfonylamines of copper phthalocyanine, and polymers having sulfonic acid groups.
However, when a charge control agent such as a metal salt is used as the charge control agent, there are many problems that the stability is low and the compatibility with the binder resin is remarkably poor. In addition, even when a polymeric charge control agent is used, the charge control agent is adsorbed on the pigment surface due to the large surface area of the pigment, because the pigment is concentrated on the toner surface during polymerization due to the surface-activeness of the pigment, A phenomenon occurs in which the amount of the charge control agent participating in the charge control actually becomes insufficient, and there arises a problem that the chargeability and the charge stability are lowered.
Accordingly, the present invention uses the polymer represented by the above formula (1) as a charge control agent, thereby remarkably improving the stability and compatibility with the binder resin and improving the chargeability of the charge control agent I can solve the problem.
According to one embodiment of the present invention, R in Formula 1 may be a branched or straight-chain alkyl group having 10 to 30 carbon atoms, preferably an alkyl group having 10 to 20 carbon atoms. In the above formula (1), when R is an alkyl group having less than 10 carbon atoms, the polymerization distribution of the toner can be widened. On the other hand, if R is an alkyl group having more than 30 carbon atoms, the transfer efficiency may be lowered.
The weight average molecular weight of the charge control agent represented by Formula 1 may be about 10,000 to about 20,000 g / mol, preferably about 12,000 to about 19,000 g / mol, more preferably about 14,000 to about 18,000 g / mol have. By using the charge control agent having a weight average molecular weight, it is possible to remarkably improve stability and compatibility with the binder resin, and to solve the problem of adsorption of the surface of the pigment on the charge control agent which lowers the chargeability and the charge stability. Particularly, in terms of high compatibility with the binder resin, it is preferable to use a polymeric charge control agent having a weight-average molecular weight of at least 10,000 g / mol in view of ensuring effective polymerization stability and uniform particle size distribution. And a polymeric charge control agent having a weight average molecular weight of about 20,000 g / mol or less in terms of maintaining the optimum viscosity of the monomer mixture.
When the charge control agent has a molecular weight of more than about 20,000 g / mol, the charge control agent does not sufficiently migrate to the particle surface, so that particles during suspension polymerization There is a high possibility that small particles are generated during homogenization of the monomer mixture when the molecular weight is less than about 10,000 g / mol.
In the present invention, the charge control agent may have an acid value of about 1 to about 40 mg KOH / g, preferably about 2 to about 38 mg KOH / g, more preferably about 3 to about 35 mg KOH / g, The glass transition temperature may be from about 30 째 C to about 120 째 C, preferably from 32 째 C to about 118 째 C, more preferably from 35 째 C to about 115 째 C. If the acid value of the charge control agent is less than about 1, the charge control agent may not act as a charge control agent. If the acid value is more than about 40, the surfactant may interfere with the monomer mixture to deteriorate the polymerization stability. If the glass transition temperature of the charge control agent is less than about 30 占 폚, friction-melting of the toner to toner may occur during printing due to the low glass transition temperature of the electron control agent exposed on the surface, thereby causing a blocking phenomenon. On the other hand, if it exceeds 120 ° C, the surface of the toner becomes excessively hard, which may deteriorate the coating property and deteriorate the fixability.
Such a charge control agent may be used in an amount of about 0.6 to about 10 parts by weight, preferably about 1 to about 8 parts by weight, more preferably about 1.5 to about 5 parts by weight, based on 100 parts by weight of the monomer mixture for binder resins. The charge control agent is preferably used in an amount of about 0.6 part by weight or more from the viewpoint of dispersion stability and is preferably used in an amount of about 10 parts by weight or less from the viewpoint of suppressing generation of fine powder by emulsion polymerization or the like.
In the present invention, the monomer for binder resin may be any monomer used in a toner produced by a polymerization method and is not particularly limited. Examples of the monomer include a styrene-based monomer, an acrylate-based monomer, a methacrylate-based monomer, and a diene-based monomer. One or more of these monomers may be used in combination. In addition, one or more acidic olefinic monomers or basic olefinic monomers may be optionally mixed with the monomer.
According to an embodiment of the present invention, the monomer includes at least one monomer selected from the group consisting of (a) a styrenic monomer and (b) an acrylate monomer, a methacrylate monomer and a diene monomer, The content of the styrene monomer (a) is about 30 to about 95 parts by weight, preferably about 32 to about 93 parts by weight, more preferably about 30 to about 95 parts by weight, relative to 100 parts by weight of the total of the monomers (a) (B) about 5 to about 70 parts by weight of at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer and a diene-based monomer is used in an amount of about 35 to about 90 parts by weight, About 7 to about 68 parts by weight, more preferably about 10 to about 65 parts by weight, and optionally (c) an acidic olefinic monomer or a basic olefinic monomer (A) and the monomer (b) is added in an amount of about 30 parts by weight or less, or about 0.1 to about 30 parts by weight, preferably about 28 parts by weight or less, based on 100 parts by weight of the sum of the monomers About 0.3 to about 28 parts by weight, more preferably about 25 parts by weight or less, or about 0.5 to about 25 parts by weight.
As aromatic vinyl monomers, styrene, monochlorostyrene, methylstyrene, dimethylstyrene and the like can be used, and they are preferably used in an amount of about 30 to about 95 parts by weight based on the total amount of monomers, more preferably about 40 to about 90 By weight, more preferably about 50 to about 80 parts by weight.
As the acrylate monomer, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate and the like can be used. As the methacrylate monomer, methyl Methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate and the like. As the dienic monomers, there can be used butadiene, isoprene Can be used. It is preferable that at least one of the acrylate monomer, the methacrylate monomer and the diene monomer is used in an amount of about 5 to about 70 parts by weight, more preferably about 10 to about 60 parts by weight, May be used in an amount of about 20 to about 50 parts by weight.
As the acidic olefinic monomer, an α, β-ethylenically unsaturated compound having a carboxyl group and the like can be used. As the basic olefinic monomer, an aliphatic alcohol having an amine group or a quaternary ammonium group, such as methacrylic acid ester, methacrylamide, vinyl Amine-based, diallylamine-based or ammonium salts thereof. When at least one of the acidic or basic olefinic monomers is used, it is preferable to use about 0.1 to about 30 parts by weight, more preferably about 0.15 to about 20 parts by weight, more preferably about 0.2 To about 10 parts by weight.
Further, about 0.01 to about 10 parts by weight, preferably about 0.05 to about 9 parts by weight, of at least one polar polymer selected from the group consisting of a polyester-based polymer and a styrene-acrylic polymer is added to 100 parts by weight of the monomer , And more preferably from about 0.1 to about 8 parts by weight, based on the weight of the composition.
The present invention further includes a step of forming a monomer mixture by incorporating a pigment together with the charge control agent and the monomer for binder resin represented by the above formula (1).
At this time, as the pigment, all the pigments used in the polymerized toner can be used, and examples thereof include metal powder type pigments, metal oxide type pigments, carbon type pigments, sulfide type pigments, chromium salt type pigments, ferrocyanide type pigments, An acid dye type pigment, a basic dye type pigment, a modand dye type pigment, a phthalocyanine type, a quinacridone type pigment and a dioxane type pigment may be used alone or in combination of two or more. In the present invention, about 1 to about 10 parts by weight, preferably about 1.5 to about 9 parts by weight, and more preferably about 2 to about 8 parts by weight of pigment may be used for 100 parts by weight of the monomer mixture.
In the step of forming the monomer mixture, in addition to the pigment, the charge control agent, and the monomer component for the binder resin, in the group consisting of wax, a reaction initiator, a crosslinking agent, a lubricant (e.g., oleic acid, stearic acid, etc.) And may further comprise at least one selected additive.
Examples of the wax include paraffin wax, microcrystalline wax, ceresin wax, carnauba wax, ester wax, polyethylene wax, and polypropylene wax. One or more of the waxes May be used in combination. In the present invention, the wax is used in an amount of about 30 parts by weight or less, or about 0.1 to about 30 parts by weight, preferably about 25 parts by weight or about 0.2 to about 25 parts by weight, more preferably about 20 parts by weight, Parts by weight or about 0.3 to about 20 parts by weight.
As the reaction initiator, an oil-soluble initiator and a water-soluble initiator may be used. Specific examples thereof include azo type initiators such as azobisisobutyronitrile and azobisvaleronitrile; Organic peroxides such as benzoyl peroxide and lauroyl peroxide; Water-soluble initiators such as potassium persulfate and ammonium persulfate, and the like, and they may be used alone or in combination of two or more thereof. The reaction initiator is preferably used in an amount of about 5 parts by weight or less, or about 0.01 to about 5 parts by weight, more preferably about 4 parts by weight or less, or about 0.05 to about 4 parts by weight, About 2.0 parts by weight or less, or about 0.1 to about 2.0 parts by weight may be used.
Examples of the crosslinking agent include divinylbenzene, ethylene dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, 1,6-hexamethylene diacrylate, allyl methacrylate, 1,1,1-trimethylol About 10 parts by weight or about 0.001 to about 10 parts by weight, preferably about 9 parts by weight or less, based on 100 parts by weight of the monomer mixture, or About 0.005 to about 9 parts by weight, more preferably about 8 parts by weight or less, or about 0.01 to about 8 parts by weight.
As the molecular weight regulator, one or more of t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, carbon tetrachloride and carbon tetrabromide may be used. 8 parts by weight or less, or about 0.001 to about 8 parts by weight, preferably about 7 parts by weight or less, or about 0.005 to about 7 parts by weight, more preferably about 6 parts by weight or about 0.01 to about 6 parts by weight .
As the lubricant and coupling agent, all additives known to be usable in the monomer mixture for producing polymerized toners may be used in an appropriate amount.
In addition, the present invention can include a charge control agent, a pigment, and a monomer as described above, and optionally, a few additives can be added to form a monomer mixture having the above-described composition.
Then, after the monomer mixture is added to the aqueous medium, the monomer mixture in the aqueous medium is uniformly dispersed in a fine droplet form, and the monomer mixture in such a fine droplet form forms the finally prepared toner particles. At this time, a homogenizer may be applied to the monomer mixture and the aqueous dispersion medium for the purpose of dispersion in the droplet form, and a method of applying homogenization by applying shear force may be applied. For example, by homogenizing the mixture with a homogenizer at a rate of from about 5,000 rpm to about 20,000 rpm, preferably from about 6,000 rpm to about 18,500 rpm, more preferably from about 8,000 rpm to about 17,000 rpm, Can be dispersed in the form of droplets in the aqueous dispersion medium.
Thereafter, suspension polymerization is carried out on the monomer mixture dispersed in the droplet form. When such suspension polymerization proceeds, polymerization proceeds in a state in which the polymerizable monomer or the like is dispersed in a fine droplet form to form a predetermined polymer or copolymer. Due to the formation of such a polymer or copolymer, toner particles containing it as a main component can be formed. In such a toner particle formation process, the suspension polymerization may be carried out at a temperature of, for example, about 60 to about 90 占 폚, preferably about 65 to about 85 占 폚, more preferably about 70 to about 80 占 폚, 20 hours, preferably about 9 to about 18 hours, and more preferably about 10 to about 15 hours, so that a polymerized toner having a uniform particle distribution can be appropriately formed.
On the other hand, after the toner particles are formed through the above-described suspension polymerization, the step of washing the toner particles to remove calcium phosphate and the step of drying the toner particles can be further carried out. As a result, A polymerized toner according to an example can be produced.
At this time, in the step of removing calcium phosphate, the water-soluble inorganic acid is dropped into the dispersion in which the toner particles are formed, in terms of solubility in the pH of the calcium phosphate as described above, to adjust the pH to about 2 or less, preferably about 1.7 or less , More preferably about 1.5 or less, by dissolving the dispersion stabilizer in an aqueous solution to separate the toner particles from the toner particles. In this way, after the dispersion stabilizer is removed, the water is removed through a filter device, and again an excessive amount of distilled water is added to dilute and remove moisture, which can be repeated several times.
Then, the pressurized fixing toner can be prepared by placing the toner cake in a vacuum oven and vacuum-drying at room temperature.
In addition, if necessary, a separate external additive such as silica may be coated on the surface of the toner. In the case of coating the external additive, an external additive is added to the toner particles using a Henschel mixer, And stirring can be carried out at a high speed. Any of those known to be usable for polymerized toners can be used as the silica.
In another preferred embodiment of the present invention, the polymerized toner of the present invention comprises a step of preparing an aqueous dispersion medium containing calcium phosphate precipitated by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride, a step of homogenizing the monomer mixture into an aqueous dispersion medium , Polymerizing the monomer mixture dispersed in the droplet form, washing and drying the polymerized polymerized toner core, and coating the polymerized toner core with the external additive. ≪ / RTI >
Hereinafter, a method for producing a polymerized toner according to a preferred embodiment of the present invention will be described in detail.
(1) Polymerization Toner Production Step
Aqueous dispersion containing calcium phosphate precipitated by mixing about 0.1 M sodium phosphate aqueous solution and about 1 M calcium chloride aqueous solution was prepared, and the monomer mixture was added to the aqueous dispersion and homogenized by a homogenizer to give a monomer mixture After the toner is dispersed in the form of droplets, the polymerization proceeds to prepare a toner core.
As the monomer, an aromatic vinyl monomer, an acrylate monomer, a methacrylate monomer, a diene monomer or a mixture thereof may be used, and an acidic or basic olefin monomer may be selectively used.
(2) Removal of calcium phosphate and drying step
In the solution containing the polymerized toner prepared above, hydrochloric acid is added to the polymerization reaction to remove the calcium phosphate from the toner first, thereby adjusting the pH to about 2 or less, preferably about 1.7 or less, more preferably about 1.5 or less, Calcium is completely dissolved in water. Thereafter, about 2 times of distilled water was added to the whole weight to dilute it, and shear force was applied by a homogenizer, followed by separation using a filter device, a filter press device, a general centrifugal separator, a continuous decanter type centrifugal separator, And the calcium phosphate can be completely separated from the polymer through the washing process. Finally, the water is removed through filtering and the toner cake is put into a vacuum oven and vacuum-dried at room temperature to prepare a polymerized toner core.
(3) External Additive Coating Step
Silica is added to the polymerized toner core using a Henschel mixer, and then the external additive is coated on the surface of the polymerized toner core under high-speed stirring for about 7 minutes at a speed of about 5,000 rpm.
The present invention also provides a polymerized toner produced by the above method. The polymerized toner may contain about 0.8 to about 30 parts by weight, preferably about 0.9 to about 27 parts by weight of a charge control agent represented by Formula 1 and having a weight average molecular weight of 10,000 to 20,000 g / mol per 100 parts by weight of the binder monomer More preferably from about 1.0 to about 25 parts by weight, and from about 2 to about 28 parts by weight, preferably from about 2.5 to about 26 parts by weight, and more preferably from about 3 to about 25 parts by weight of pigment . If necessary, about 35 parts by weight or about 3 to about 35 parts by weight, preferably about 32 parts by weight, or about 3.5 to about 32 parts by weight, more preferably about 35 parts by weight or less, of wax is added to 100 parts by weight of the binder resin monomer About 30 parts by weight or less, or about 4 to about 30 parts by weight; About 10 parts by weight or less, or about 0.03 to about 10 parts by weight, preferably about 9 parts by weight, or about 0.04 to about 9 parts by weight, more preferably about 8 parts by weight, or about 0.05 to about 8 parts by weight ; About 15 parts by weight or less, or about 0.003 to about 15 parts by weight, preferably about 14 parts by weight or about 0.004 to about 14 parts by weight, more preferably about 13 parts by weight or about 0.005 to about 13 parts by weight of crosslinking agent; Or from about 0.003 to about 12 parts by weight, preferably up to about 11 parts by weight, or from about 0.004 to about 11 parts by weight, more preferably up to about 10 parts by weight, or from about 0.005 to about 10 parts by weight, And the like may be optionally included.
Further, it is also possible to coat silica or the like on the toner surface with the thus prepared toner particles as a toner core.
As described above, when the method of producing a polymerized toner according to the embodiment of the present invention is applied, suspension polymerization reaction is carried out in the optimal amount of calcium phosphate and a polymeric charge control agent having a predetermined molecular weight range, The toner of the present invention can be effectively produced. Particularly, the polymerized toner produced according to the present invention is characterized in that it is easy to control the toner particle size distribution with a narrow particle diameter distribution and the reproducibility of the quality of the produced toner is very easy. In addition, the polymerized toner can achieve a high transfer efficiency and a uniform image, and can exert excellent performance in electrophotographic development and the like.
Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.
<Examples>
Example One
Of the polymerized toner Produce
686 parts by weight of 0.1 M sodium phosphate aqueous solution and 100 parts by weight of 1 M calcium chloride were mixed with 500 parts by weight of water to prepare an aqueous dispersion of monomers in the form of calcium phosphate crystals precipitated in an aqueous solution and then heated to a reaction temperature of 70 캜 , And the mixture was further stirred for 20 minutes. The content of calcium phosphate in the aqueous dispersion was 3 parts by weight based on 100 parts by weight of the following monomer mixture.
160 parts by weight of styrene, 36 parts by weight of n-butyl acrylate and 4 parts by weight of acrylic acid were used as a monomer, 4 parts by weight of allyl methacrylate as a crosslinking agent and 0.4 part by weight of n-dodecylmercaptan as a molecular weight modifier were added, 10 parts by weight of the pigment was stirred with a bead mill at 2,000 rpm for 2 hours, and then the beads were removed to obtain a mixture containing a monomer, a pigment, and a charge control agent 225 parts by weight of a monomer mixture was finally prepared.
The mixture was heated to 70 DEG C with water bath, 20 parts by weight of paraffin wax was added, and the mixture was stirred for 20 minutes to prepare a monomer mixture. The monomer mixture was homogenized at a rate of 13,000 rpm using an aqueous dispersion and a homogenizer, The monomer mixture was dispersed in the form of fine droplets and then reacted for 15 hours while stirring at 200 rpm with a paddle type stirrer to prepare a polymerized toner.
On the other hand, the charge control agent represented by the following formula (1) was used.
[Chemical Formula 1]
In Formula 1,
R is And a linear alkyl group having 10 carbon atoms, and l, m, and n are 35, 28, and 7, respectively.
Cleaning with a centrifuge
To the aqueous dispersion solution containing the polymerized toner synthesized above, hydrochloric acid was added to adjust the pH to less than 2 to dissolve the calcium phosphate in the water, diluted by adding 2 times of distilled water to the total weight, and the shear force was measured with a homogenizer Followed by centrifugation at 3,000 rpm for 15 minutes using a centrifugal separator (Beckman J2-21M, Rotor JA-14). The polymerized liquid containing the polymerized toner was further diluted by adding 2 times of distilled water, and then sheared with a homogenizer. After centrifugation at 3,000 rpm for 15 minutes using a centrifuge (Beckman J2-21M, Rotor JA-14) The separation process was repeated twice to remove calcium phosphate on the surface of the toner. Finally, the water was removed by filtration, and the toner cake was placed in a vacuum oven and vacuum-dried at room temperature for 48 hours to prepare a polymerized toner core. The prepared polymerized toner core had a volume average particle diameter of 7 mu m and a ratio of volume average particle diameter to number average particle diameter of 1.26.
External additive coating
2 parts by weight of silica was added to 100 parts by weight of the polymerized toner core using a Henschel mixer, and then the external additives were coated on the surface of the polymerized toner core at a speed of 5,000 rpm for 7 minutes under high-speed stirring.
Example 2
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having a weight average molecular weight of 12,000 g / mol was used as the charge control agent and R = a linear alkyl group having 10 carbon atoms.
Example 3
A polymerized toner was prepared in the same manner as in Example 1 except that the content of the charge control agent was changed to 1.5 parts by weight based on 100 parts by weight of the monomer mixture.
Example 4
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having a weight average molecular weight of 16,500 g / mol was used as the charge control agent and R = a linear alkyl group having 20 carbon atoms.
Comparative Example One
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having R = H (hydrogen) as a charge control agent and having a weight average molecular weight of 16,50 g / mol was used.
Comparative Example 2
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having a weight average molecular weight of 16,500 g / mol was used as the charge control agent and R = a linear alkyl group having 35 carbon atoms.
Comparative Example 3
A polymerized toner was prepared in the same manner as in Example 1 except that the content of the charge control agent was changed to 12 parts by weight with respect to 100 parts by weight of the monomer mixture.
Comparative Example 4
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having a weight average molecular weight of 22,000 g / mol was used as the charge control agent and R = a linear alkyl group having 10 carbon atoms.
Comparative Example 5
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having a weight average molecular weight of 16,500 g / mol was used as the charge control agent and R = a linear alkyl group having 8 carbon atoms.
Comparative Example 6
A polymerized toner was prepared in the same manner as in Example 1, except that a polymer having a weight average molecular weight of 16,500 g / mol was used as the charge control agent and R = a linear alkyl group having 5 carbon atoms.
<Experimental Example>
The polymerized toners prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were evaluated for physical properties as follows.
Transfer efficiency of toner
After the surface of the supply portion of the cartridge was filled with toner, the entire weight of the supply portion was measured. Then, a rectangle with a width of 19 cm and a length of 1.5 cm was printed on an A4 paper sheet of 1,000 sheets, And the amount of toner consumption was calculated as shown in the following equation (1).
[Equation 1]
Consumption (g) = 1,000 sheets Weight before dispensing - 1,000 shots Weight after dispensing
In addition, the weight of the drum portion separable from the feeding portion was measured before printing, after printing, and the amount of toner that could not be transferred to paper was calculated as shown in Equation 2 below.
[Equation 2]
Amount of toner to be wasted (g) = 1,000 sheets Weight of drum after printing - 1,000 sheets Weight of drum before printing
After the amount of consumed and wasted toner was measured as described above, the transfer efficiency was calculated by the following equation 3. < EMI ID = 3.0 >
[Equation 3]
Transfer efficiency (%) = {(consumption amount - amount of wasted toner) / consumption amount} * 100
Image uniformity
After printing on A4 size paper with a laser printer (HP2600, manufacturer: Hewlett-Packard), image density was measured at four corner portions and one central portion of the printing paper using an image density meter (RD918, Macbath) The image uniformity was judged to be uniform. When the difference in the measured value was less than 0.1, the image uniformity was judged to be normal. When the difference in the measured value was 0.1 or more, it was judged that the image was uneven.
The measurement results for the average particle diameter, standard deviation, transfer efficiency evaluation, and image uniformity of the polymerized toners prepared according to Examples 1 to 4 and Comparative Examples 1 to 6 are as shown in Table 1 below.
(Unit: g / mol)
(Unit: parts by weight)
(Unit: 占 퐉)
Uniformity
efficiency
(unit:%)
As shown in Table 1, according to the present invention, an appropriate amount of calcium phosphate is used as an aqueous dispersion stabilizer, and a charge control agent having an alkyl chain having an appropriate chain length (10 to 30 carbon atoms) It can be seen that the polymerized toners of Examples 1 to 4 have very good physical properties in terms of particle diameter distribution, transfer efficiency and image uniformity as compared with Comparative Examples 1 to 6 in which the content, the kind of charge control agent, and the molecular weight range are out of the range of the present invention have.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the invention.
Claims (17)
Forming a monomer mixture comprising a charge control agent, a pigment, and a binder resin monomer having a weight average molecular weight of 10,000 to 20,000 g / mol represented by the following formula (1);
Dispersing the monomer mixture in the form of droplets in the aqueous dispersion medium; And
Wherein the charge control agent is used in an amount of 2 to 6 parts by weight based on 100 parts by weight of the monomer mixture and the charge control agent is used in an amount of 0.6 to 10 parts by weight based on 100 parts by weight of the monomer mixture, : ≪
[Chemical Formula 1]
In Formula 1,
R is a branched or straight-chain alkyl group having 10 to 30 carbon atoms,
l, m and n are the same as or different from each other and each is an integer of 1 to 40, and l: (m + n) is 3:97 to 15:85.
Wherein said calcium phosphate is obtained by mixing an aqueous phosphate solution and an aqueous calcium salt solution.
Further comprising the step of dropping the water-soluble inorganic acid into the phosphate aqueous solution and then adding an aqueous calcium salt solution to adjust the pH of the aqueous dispersion medium to 4 to 7. [
Wherein the charge control agent has a weight average molecular weight of 12,000 to 19,000 g / mol.
The step of dispersing the monomer mixture in the form of droplets in the aqueous dispersion medium comprises mixing the monomer mixture and the aqueous dispersion medium and homogenizing the mixture with a homogenizer at a speed of 5,000 rpm to 20,000 rpm A method for producing a polymerized toner.
Washing the toner particles produced after the suspension polymerization step to remove calcium phosphate, and drying the toner particles.
Further comprising the step of dropping a water-soluble inorganic acid into the suspension polymerization liquid to adjust the pH to 2.0 or less before performing the washing step.
Wherein the monomer for binder resin is at least one selected from the group consisting of an aromatic vinyl monomer, an acrylate monomer, a methacrylate monomer and a diene monomer.
Wherein the pigment is selected from the group consisting of a metal powder type pigment, a metal oxide type pigment, a carbon type pigment, a sulfide type pigment, a chromium salt type pigment, a ferrocyanide type pigment, an azo type pigment, an acid type dye type pigment, a basic dye type pigment, , Phthalocyanine, quinacridone-type pigment, and dioxane-type pigment.
Wherein the monomer mixture further comprises at least one additive selected from the group consisting of a wax, a reaction initiator, a crosslinking agent, a lubricant, a molecular weight modifier, and a coupling agent.
Wherein the wax is at least one selected from the group consisting of paraffin wax, microcrystalline wax, ceresin wax, carnauba wax, ester wax, polyethylene wax and polypropylene wax.
Wherein the reaction initiator is at least one selected from the group consisting of azobisisobutyronitrile, azobisvaleronitrile, benzoyl peroxide, lauroyl peroxide, potassium persulfate, and ammonium persulfate.
The crosslinking agent may be selected from the group consisting of divinylbenzene, ethylene dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, 1,6-hexamethylene diacrylate, allyl methacrylate, 1,1,1-trimethylol Propanetriacrylate, triallylamine, and tetraallyloxyethane. The method for producing a polymerized toner according to claim 1,
Wherein the molecular weight regulator is at least one selected from the group consisting of t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, carbon tetrachloride and carbon tetrabromide.
0.8 to 30 parts by weight of a charge control agent represented by the following general formula (1) and having a weight average molecular weight of 10,000 to 20,000 g / mol with respect to 100 parts by weight of a monomer for a binder resin, and 2 to 28 parts by weight of a pigment:
[Chemical Formula 1]
In Formula 1,
R is a branched or straight-chain alkyl group having 10 to 30 carbon atoms,
l, m and n are the same as or different from each other and each is an integer of 1 to 40, and l: (m + n) is 3:97 to 15:85.
Wherein the polymerization initiator further comprises at least one member selected from the group consisting of wax at 35 parts by weight or less, reaction initiator at 10 parts by weight, crosslinking agent at 15 parts by weight or less, and molecular weight adjuster at 12 parts by weight or less based on 100 parts by weight of the monomer for binder resin. toner.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020130030425A KR20140115634A (en) | 2013-03-21 | 2013-03-21 | Process for preparing polymerized toner |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020130030425A KR20140115634A (en) | 2013-03-21 | 2013-03-21 | Process for preparing polymerized toner |
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