KR20220089375A - Polymerized toner and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a polymerized toner and a method for manufacturing the same, comprising toner particles comprising a binder resin, a pigment, a dispersant, TiO ₂ , a charge control agent and a wax, and wherein the average particle diameter of TiO ₂ in the toner particles is 500 nm or less The polymerized toner prepared according to the present invention has excellent physical properties capable of realizing a uniform image with high image density and excellent transfer efficiency with a narrow particle size distribution. When the polymerized toner of the present invention is used, the transfer efficiency is 95% or more, and the image density on the printing paper is 1.35 or more, which can have very good physical properties. As such, by having a high transfer efficiency of 95% or more, there is an advantage in that a high image density can be realized with a small amount of consumption. Therefore, the polymerized toner of the present invention can be effectively applied to fields such as electrophotographic development and printing that require the realization of high and uniform images, and it is expected that excellent quality printing results can be obtained by using the polymerized toner.

Description

Polymerized toner and manufacturing method thereof

The present invention relates to a polymerized toner and a method for manufacturing the same, and more particularly, by adding TiO ₂ as an essential component together with a binder resin, a pigment, a dispersant, a charge control agent, and a wax to the toner particles of the polymerized toner, a high image density and a color polymerized toner capable of realizing excellent transfer efficiency, and a method for manufacturing the same.

Toner is used for electrophotographic development, electrostatic printers, copiers, etc., and refers to a paint that can form a desired pattern by being transferred and fixed on an object to be transferred. Recently, as the creation of documents using computers has become common, the demand for image forming apparatuses such as printers is rapidly increasing, and accordingly, the amount of toner used is also increasing.

In general, as a method of manufacturing a toner, there are a manufacturing method using pulverization and a manufacturing method using polymerization. A manufacturing method using pulverization, which is the most widely known method, prepares toner particles by putting a resin and a pigment together through a melt-mixing process, melt-mixing or extruding them, then pulverizing and classifying them. However, the toner particles produced by this process have a wide particle size distribution and very irregular shapes, such as sharp corners, and thus have poor chargeability and flowability.

In order to solve this problem, a method for preparing spherical toner particles by polymerization has been proposed. Emulsion polymerization (agglomeration) and suspension polymerization are known as methods for producing toners by the polymerization method. However, the emulsion polymerization method is difficult to control particle size distribution and has a problem in the quality reproducibility of the manufactured toner. A method of preparing a toner by polymerization is more preferred.

As described above, the toner produced by suspension polymerization is prepared by uniformly dispersing various additives such as a binder resin monomer and pigment, wax, charge control agent or initiator, and dispersing the mixture in the form of fine droplets in an aqueous dispersion. It is then subjected to a post-polymerization process.

However, in order to realize a high image density, it is necessary to increase the pigment concentration in the toner particles, and accordingly, the raw material cost increases due to the high pigment concentration, and there is a problem in dispersion due to aggregation of the pigment in the particles.

Therefore, there is a need for research on the development of polymerized toners capable of realizing high image density and excellent transfer efficiency.

Accordingly, the present inventors added TiO ₂ as an essential component together with binder resin, pigment, dispersant, charge control agent and wax to toner particles when manufacturing polymerized toner, thereby exhibiting high image density when applied to printing and polymerized toner having excellent transfer efficiency. The present invention was completed by finding that it can be prepared.

Accordingly, the technical problem to be solved in the present invention is to provide a polymerized toner capable of realizing high image density and excellent transfer efficiency, thereby exhibiting very excellent printing performance in the field of electrophotographic development.

Another technical problem to be solved by the present invention is to provide a method for manufacturing the polymerized toner.

In order to solve the above technical problem, the present invention

A polymerized toner comprising:

a binder resin, a pigment, a dispersant, TiO ₂ , a charge control agent, and toner particles comprising a wax,

Provided is a polymerized toner, wherein an average particle diameter of TiO ₂ in the toner particles is 500 nm or less.

Preferably, the toner particles include 50 to 95% by weight of a binder resin, 1 to 20% by weight of a pigment, 0.1 to 20% by weight of a pigment dispersant, 0.1 to 2% by weight of TiO ₂ , 0.1 to 5% by weight of a charge control agent, and 0.1 to 30% by weight of a wax It is characterized in that it contains % by weight.

Preferably, the binder resin is a styrene-based monomer, an acrylate-based monomer, a methacrylate-based monomer, a diene-based monomer, an acidic olefin-based monomer, a basic olefin-based monomer, or a polymer or copolymer of a mixture thereof.

Preferably, the binder resin comprises (a) a styrenic monomer; and (b) a polymer or copolymer of at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer, and a diene-based monomer.

Preferably, the binder resin is a styrene-based monomer of (a), (b) at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer and a diene-based monomer, and (c) an acidic olefin-based monomer. It is characterized in that it is a polymer or copolymer of a monomer obtained by polymerizing one or more monomers selected from the group consisting of monomers and basic olefinic monomers.

Preferably, the toner particles further include at least one additive selected from the group consisting of a reaction initiator, a crosslinking agent, a molecular weight control agent, a lubricant, and a coupling agent.

Preferably, the toner particles have an average particle diameter of 4 to 10 μm.

In order to solve the other technical problems described above, the present invention provides a method for preparing a polymerized toner including toner particles, characterized in that it is prepared according to a method comprising the steps of:

(S1) preparing an aqueous dispersion containing a dispersant;

(S2) preparing a mixture by mixing a binder resin, a pigment, TiO ₂ , a charge control agent and a wax; and

(S3) preparing toner particles by adding the mixture prepared in step (S2) to the aqueous dispersion prepared in step (S1) and then performing suspension polymerization.

Preferably, in the step (S2) of the method for preparing a polymerized toner of the present invention, after adding the pigment, milling is performed with a bead mill at a stirring speed of 8,000 to 20,000 rpm for 10 to 120 min.

Preferably, the milling process of the method for preparing the polymerized toner of the present invention is characterized in that it is performed by adding 20 to 50 parts by weight of beads based on 100 parts by weight of the mixture of step (S2).

Preferably, in the step (S3) of the method for preparing a polymerized toner of the present invention, the suspension polymerization is performed at 60 to 90° C. for 8 to 20 hours.

Preferably, the method for preparing the polymerized toner of the present invention comprises the steps of (1) removing the dispersant; and (2) drying the toner particles.

Preferably, the method for preparing the polymerized toner of the present invention further comprises the step of coating the outside of the toner particles prepared in step (S3).

The polymerized toner prepared according to the present invention has excellent physical properties capable of realizing a uniform image with high image density and excellent transfer efficiency with a narrow particle size distribution. When the polymerized toner of the present invention is used, the transfer efficiency is 95% or more, and the image density on the printing paper is 1.35 or more, which can have very good physical properties. As described above, by having a high transfer efficiency of 95% or more, there is an advantage in that a high image density can be realized with a small amount of consumption. Therefore, the polymerized toner of the present invention can be effectively applied to fields such as electrophotographic development and printing that require the realization of high and uniform images, and it is expected that excellent quality printing results can be obtained by using the polymerized toner.

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

The present invention provides a polymerized toner, comprising toner particles comprising a binder resin, a pigment, a dispersant, TiO ₂ , a charge control agent, and a wax, and wherein the average particle diameter of TiO ₂ in the toner particles is 500 nm or less. provides

According to one embodiment of the present invention, the toner particles include 50 to 95% by weight of a binder resin, 1 to 20% by weight of a pigment, 0.1 to 20% by weight of a pigment dispersant, 0.1 to 2% by weight of TiO ₂ , 0.1 to 5% by weight of a charge control agent % by weight, and 0.1 to 30% by weight of wax.

In the polymerized toner of the present invention, TiO ₂ is used in toner particles to realize high image density and high transfer efficiency of the polymerized toner, and is added to the toner particles in an amount of 0.1 to 2 wt%. At this time, if the amount of TiO ₂ is less than 0.1 wt%, image density and transfer efficiency are not improved _. Efficiency can also be significantly reduced.

According to one embodiment of the present invention, the TiO ₂ average particle diameter formed in the polymerized toner particles of the present invention may be 10 nm to 500 nm, preferably 10 nm to 400 nm.

When the TiO ₂ average particle diameter is less than 10 nm, it is difficult to obtain excellent image density and transfer efficiency, which are the objective effects of the present invention _. The concentration may drop and the transfer efficiency may also be significantly reduced.

It is preferable that TiO ₂ is uniformly dispersed together with the pigment in the polymerized toner particles of the present invention.

The binder resin used in the present invention may be used without particular limitation as a binder resin for toner formation prepared by suspension polymerization, and various monomers or polymers or copolymers thereof may be used.

Examples of the binder resin monomer include a styrene-based monomer, an acrylate-based monomer, a methacrylate-based monomer, a diene-based monomer, an acidic olefin-based monomer, a basic olefin-based monomer, or a polymer or copolymer of a mixture thereof. It is not limited.

According to one embodiment of the present invention, the binder resin is (a) a styrenic monomer; and (b) a polymer or copolymer of at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer, and a diene-based monomer. In this case, the polymer comprises 30 to 95 parts by weight of the monomer of (a) and 5 to 70 parts by weight of the monomer of (b) with respect to a total of 100 parts by weight of the sum of the monomers of (a) and (b). It may be polymerized.

According to one embodiment of the present invention, the polymer is a styrenic monomer of (a), (b) at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer and a diene-based monomer; and (c) one or more monomers selected from the group consisting of acidic olefinic monomers and basic olefinic monomers may be polymerized. In this case, the monomer of (c) may be polymerized in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the total of the monomers of (a) and (b).

The styrene-based monomer includes styrene, monochlorostyrene, methylstyrene, dimethylstyrene, and the like, and the acrylate-based monomer includes methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, and dodecyl acrylic. late, 2-ethylhexyl acrylate, and the like. And, the methacrylate-based monomer includes methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, and the like. Examples of the diene-based monomer include butadiene and isoprene.

As the acidic olefinic monomer, α,β-ethylenically unsaturated compounds having a carboxyl group can be used, and as the basic olefinic monomer, a methacrylic acid ester of an aliphatic alcohol having an amine group or a quaternary ammonium group, methacrylamide, A vinyl amine type, a diallyl amine type, its ammonium salt, etc. can be used.

The binder resin may be included in the toner particles in an amount of 50 to 95% by weight, preferably 60 to 93% by weight, and more preferably 70 to 90% by weight. At this time, if the content of the binder resin is out of the above range, it is difficult to obtain a uniform image with excellent image density and excellent transfer efficiency, and at the same time, it is possible to effectively prevent an offset phenomenon, which is a phenomenon in which the toner contaminates the fixing roll during the fixing process. none.

The charge control agent used in the present invention may be a cationic charge control agent, an anionic charge control agent, or a mixture thereof. Examples of the cationic charge control agent include nigrosine-type dyes, high aliphatic metal salts, alkoxy amines, chelates, quaternary ammonium salts, alkylamides, fluorine treatment activators, metal salts of naphthalene acid, or mixtures thereof, and the anionic charge control agent chlorinated paraffins, chlorinated polyesters, polyesters containing acids, sulfonylamines of copper phthalocyanine, sulfonic acid groups, or mixtures thereof.

According to one embodiment of the present invention, it is preferable to use a copolymer having a sulfonic acid group as the charge control agent, and more preferably, a copolymer having a sulfonic acid group having a weight average molecular weight of 2,000 to 200,000 may be used, Even more preferably, a copolymer having a sulfonic acid group having an acid value of 1 to 40 mg KOH/g and a glass transition temperature of 30 to 120° C. may be used.

At this time, if the acid value of the copolymer is less than 1, it does not act as a charge control agent, and if the acid value of the copolymer is more than 40, it affects the interfacial properties of the mixture and deteriorates polymerization stability.

In addition, if the glass transition temperature of the copolymer is less than 30 ° C., friction-melting of toner to toner occurs during printing due to the low glass transition temperature of the charge control agent exposed on the surface, thereby causing a blocking phenomenon. When the glass transition temperature is higher than 120° C., the surface of the toner is excessively hardened, which is undesirable in the physical properties of coating properties and fixing properties.

On the other hand, if the weight average molecular weight of the copolymer is less than 2,000, the surface concentration may be lowered due to high compatibility with the binder resin, and thus may not function as a charge control agent. Due to the increase in viscosity of the mixture, it is undesirable for polymerization stability and particle size distribution.

Specific examples of the copolymer having a sulfonic acid group include, but are not limited to, a styrene-acrylic copolymer having a sulfonic acid group, a styrene-methacrylic copolymer having a sulfonic acid group, or a mixture thereof.

The charge control agent may be included in the toner particles in an amount of 0.1 to 5% by weight, preferably 0.3 to 4% by weight, and more preferably 0.5 to 3% by weight. At this time, if the content of the charge control agent is out of the above range, it is difficult to obtain a uniform image with excellent image density and excellent transfer efficiency, and at the same time, it is possible to effectively prevent an offset phenomenon, which is a phenomenon in which the toner contaminates the fixing roll during the fixing process. none.

Examples of the wax used in the present invention include petroleum refining waxes such as paraffin wax, microcrystalline wax, or ceresin wax; natural waxes such as carnuba wax; Alternatively, one or more synthetic waxes or mixtures thereof such as polyester wax, polyethylene wax, or polypropylene wax may be used.

The wax may be included in the toner particles in an amount of 0.1 to 30% by weight, preferably 1 to 25% by weight, and more preferably 5 to 20% by weight. In this case, when the content of the wax is used within the above range, a uniform image with excellent image density and excellent transfer efficiency can be obtained.

The pigment used in the present invention is a yellow pigment used while being dispersed in a binder resin, and may preferably be carbon black.

The pigment may be included in the toner particles in an amount of 1 to 20% by weight, preferably 2 to 15% by weight, and more preferably 3 to 10% by weight. At this time, when the content of the pigment is used within the above range, it is possible to realize a uniform image and excellent transfer efficiency with excellent image density of the polymerized toner, and at the same time effectively prevent an offset phenomenon, which is a phenomenon in which the toner contaminates the fixing roll during the fixing process. have.

The dispersing agent used in the present invention prevents aggregation between particles such as a monomer for binder resin or carbon black existing in the form of droplets in an aqueous medium, and allows these particles to be uniformly dispersed. In addition, the dispersant serves to stabilize the droplet particles by uniformly adsorbing on the droplet surface. In addition, the dispersant may be solubilized through an acid or alkali treatment, or washing with hot water after the polymerization reaction is completed in an aqueous medium, and separated from the toner particles.

The dispersant may include an inorganic dispersant, an organic dispersant, an anionic surfactant, or a mixture thereof. Such a dispersant may be included in the toner particles in an amount of 0.1 to 20% by weight, preferably 0.2 to 15% by weight, and more preferably 0.3 to 10% by weight. In this case, when the content of the dispersant is used within the above range, uniform images and excellent transfer efficiency are achieved with excellent image density of the polymerized toner, and at the same time, it is possible to effectively prevent an offset phenomenon, which is a phenomenon in which the toner contaminates the fixing roll during the fixing process. have.

Specific examples of the inorganic dispersant include calcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, hydroxy apatite, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, or mixtures thereof, and the like.

Specific examples of the water-soluble organic dispersant include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxy propyl cellulose, ethyl cellulose, carboxyl methyl Cellulose (carboxyl methyl cellulose) and its sodium salt, polyacrylic acid and its salt, starch (starch) or a mixture thereof, and the like.

Specific examples of the anionic surfactant include fatty acid salts, alkyl sulfate salts, alkylaryl sulfate salts, dialkylsulfosuccinates, alkyl phosphates, or mixtures thereof.

According to one embodiment of the present invention, a more preferred example of the dispersant may be calcium phosphate. Such calcium phosphate may be obtained in the form of crystals in an aqueous solution by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride, and the aqueous dispersion may be in a form in which calcium phosphate crystals are uniformly dispersed in water.

According to one embodiment of the present invention, the toner particles may further include one or more additives selected from the group consisting of a reaction initiator, a crosslinking agent, a molecular weight regulator, a lubricant (eg, oleic acid, stearic acid, etc.), and a coupling agent. and these additives may be included in the toner particles in an amount of 0.1 to 10% by weight.

In this case, the reaction initiator may be used in an amount of 0.1 to 10% by weight, preferably 0.3 to 8% by weight, more preferably 0.5 to 5% by weight of the toner particles, and the crosslinking agent is 0.01 to 5% by weight to the toner particles. It may be used in an amount of weight %, preferably 0.05 to 4 weight %, more preferably 0.1 to 3 weight %, and the molecular weight modifier is 0.1 to 10 weight %, preferably 0.3 to 8 weight %, to the toner particles; More preferably, it may be used in an amount of 0.5 to 5% by weight, and the lubricant (eg, oleic acid, stearic acid, etc.) is added to the toner particles in an amount of 0.01 to 5% by weight, preferably 0.05 to 4% by weight, more preferably 0.1 to 3% by weight, and the coupling agent may be further included in an amount of 0.01 to 5% by weight, preferably 0.05 to 4% by weight, and more preferably 0.1 to 3% by weight of the toner particles.

As the reaction initiator, an oil-soluble initiator and a water-soluble initiator may be used. Specifically, azo initiators, such as azobisisobutyronitrile and azobisvaleronitrile; organic peroxides such as benzoyl peroxide and lauroyl peroxide; A commonly used water-soluble initiator such as calcium persulfate and ammonium persulfate may be used, and one type or a mixture of two or more types may be used.

The crosslinking agent is divinylbenzene, ethylene dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, 1,6-hexamethylene diacrylate, allyl methacrylate, 1,1,1-trimethylol propane triacrylate, triallylamine, tetraallyloxyethane, or mixtures thereof.

The molecular weight modifier may include t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, carbon tetrachloride, or a mixture thereof.

As the lubricant and coupling agent, those known to be applicable to the preparation of polymerized toner may be used without particular limitation.

According to one embodiment of the present invention, the toner particles may further include a coating layer including an external additive such as silica, titanium dioxide, or a mixture thereof. Such an external additive may be present in the form of coating on the outermost portion of the toner particles.

The silica is preferably surface-treated with a silane compound such as dimethyldichlorosilane, dimethylpolysiloxane, hexamethyldisilazane, aminosilane, alkylsilane or octamethylcyclotetrasiloxane.

The titanium dioxide may be used alone or in combination with a rutile stable at high temperature or an anatase structure stable at a low temperature, and having a particle size of 80 to 200 nm, preferably 100 to 150 nm can be applied

According to one embodiment of the present invention, the average particle diameter of the toner particles in the polymerized toner of the present invention may be 4 to 10 μm, preferably 5 to 8 μm, and more preferably 6 to 7 μm. The average particle diameter of these toner particles may be 4 μm or more in terms of image density and scattering prevention, and the average particle diameter of the toner particles may be 10 μm or less in terms of consumption reduction.

It is preferable that TiO ₂ is uniformly dispersed together with the pigment in the polymerized toner particles of the present invention.

The polymerized toner prepared according to the present invention has excellent physical properties capable of realizing a uniform image with high image density and excellent transfer efficiency with a narrow particle size distribution. Specifically, when the polymerized toner of the present invention is used, the transfer efficiency is 95% or more, and the image density on the printing paper is 1.35 or more, which can have very excellent physical properties. As such, by having a high transfer efficiency of 90% or more, there is an advantage in that a high image density can be realized with a small amount of consumption. In addition, there is an advantage of having an excellent image density of 1.35 or more with excellent transfer efficiency.

On the other hand, the present invention provides a method for preparing a polymerized toner comprising toner particles, characterized in that it is prepared according to a method comprising the steps of:

(S1) preparing an aqueous dispersion containing a dispersant;

(S2) preparing a mixture by mixing a binder resin, a pigment, TiO ₂ , a charge control agent and a wax; and

(S3) adding the mixture prepared in step (S2) to the aqueous dispersion prepared in step (S1) and then performing suspension polymerization to form toner particles.

According to one embodiment of the present invention, in the step of preparing the aqueous dispersion including the dispersing agent of step (S1), the dispersing agent may be mixed with water to form an aqueous dispersion. In order to homogenize such an aqueous dispersion, a step of stirring or applying a shear force may be applied. Specifically, preparing the aqueous dispersion may include mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution to obtain calcium phosphate in the form of crystals in the aqueous solution. Such calcium phosphate may be used as a dispersant, and the aqueous dispersion may be in a form in which calcium phosphate crystals are uniformly dispersed in water.

According to one embodiment of the present invention, in the step of preparing the mixture of step (S2), it is preferable to perform a milling process for 10 to 120 min with a bead mill under a stirring speed of 8,000 to 20,000 rpm with a bead mill after adding the pigment do.

By performing the milling process under optimal conditions, a polymerized toner having the average particle diameter of the pigment aggregates within a predetermined range as described above can be prepared, and the polymerized toner thus prepared has a high image density when applied to printing. Not only can it have, but also high transfer efficiency can be realized.

In particular, in the present invention, the step of preparing the mixture of step (S2) is a stirring speed of 8,000 to 20,000 rpm, preferably 9,000 to 18,000 rpm, more preferably 10,000 to 14,000 rpm after adding the pigment in the container. It is preferred to mill with stirring for 10 to 120 min, preferably for 20 to 100 min, more preferably for 30 to 60 min.

At this time, if the stirring speed is less than 8,000 rpm, it may be difficult to uniformly disperse the pigment in the mixture. may become excessively large.

In addition, the size of the pigment agglomerate may vary depending on the milling time, and when the milling time is shorter than 20 min, the pigment is concentrated on the toner particle surface to decrease the chargeability of the toner particle, thereby reducing the transfer efficiency. can Conversely, when the milling process is performed for a longer time than necessary because the milling time exceeds 50 min, the surface of the yellow pigment is damaged, the size of the pigment aggregate increases, and the chargeability of the toner particles is lowered. This may reduce the transfer efficiency.

The milling process may be performed using a bead mill in an amount corresponding to half the volume of the mixture, and the bead mill may be used in a size having a diameter of 0.1 to 1 mm, preferably 0.2 to 0.5 mm.

In the step of preparing the mixture of step (S2) through this milling process, a polymerized toner having an average particle diameter of the pigment agglomerates formed in the toner particles of 500 nm or less is manufactured, and high image density and transfer efficiency can be realized.

According to one embodiment of the present invention, in the milling process, 20 to 50 parts by weight, preferably 22 to 48 parts by weight, more preferably 25 to 45 parts by weight of beads based on 100 parts by weight of the mixture are added. can be done by

In the step of preparing the mixture of step (S2), the mixture may be formed by mixing and sufficiently dissolving a binder resin, a pigment, a pigment dispersant, TiO ₂ , a charge control agent and a wax, and homogenizing it in an aqueous dispersion using a homogenizer can do it

Toner particles may be formed by mixing the mixture with the aqueous dispersion and suspension polymerization. More specifically, the forming of the toner particles may include: adding the mixture to the aqueous dispersion; applying a shear force to the aqueous dispersion and mixture to homogenize the mixture in the form of droplets in the aqueous dispersion; and suspension polymerization of the homogenized mixture. And, as described above, the mixture and the aqueous dispersion may be homogenized using a homogenizer.

According to one embodiment of the present invention, in the step of adding the mixture of step (S3) to the aqueous dispersion to form toner particles by suspension polymerization, the mixture is uniformly dispersed in the aqueous dispersion in the form of fine water droplets (droplets). Thus, the polymerization reaction can form spherical toner particles of an appropriate size. For dispersion in the form of such fine water droplets (droplets), a shear force is applied to the mixture and the aqueous dispersion using a homogenizer to homogenize. Specifically, the mixture mixed with the aqueous dispersion using a homogenizer is 5,000 By homogenizing at a speed of rpm to 20,000 rpm, preferably 8,000 rpm to 17,000 rpm, the mixture may be dispersed in the form of fine droplets in the aqueous dispersion.

The suspension polymerization may be performed at 60 to 90 °C for 8 to 20 hours. As a more preferred example, in the suspension polymerization, the suspension polymerization reaction is performed at 50 to 70° C. for 8 to 12 hours, and then the temperature is raised to 80 to 110° C., and the reaction may be performed for 30 minutes to 4 hours.

According to one embodiment of the present invention, a method for preparing a polymerized toner of the present invention comprises the steps of (1) removing a dispersant; and (2) drying the toner particles.

The step (1) of removing the dispersant may include adjusting the pH to a suitable pH for dissolving the dispersant. By adding a water-soluble inorganic acid such as hydrochloric acid or nitric acid to the dispersion in which the toner particles are produced to adjust the pH to 2 or less, preferably 1.5 or less, the dispersing agent can be dissolved in an aqueous solution and removed from the toner particles. In this dispersing agent removal step, the toner slurry containing less than 50% by weight of water can be obtained using a filtration device after the pH is appropriately adjusted and stirred for at least 5 hours to sufficiently dissolve the dispersant. In addition, in the step of removing the dispersant, a step of homogenizing the solution by applying a shear force with a homogenizer and a separation step using a centrifugal separator may be applied. In addition, after the above-described dispersing agent removal step, the dispersing agent can be more efficiently removed through the process of repeatedly removing moisture using a filter device and adding an excess of distilled water several times.

Drying the toner particles (2) includes placing a toner cake from which the dispersant has been removed in a vacuum oven and vacuum drying at room temperature. However, the present invention is not limited thereto, and a drying method known to be commonly used in the manufacturing step of polymerized toner may be used without particular limitation.

According to one embodiment of the present invention, the method for preparing a polymerized toner of the present invention may further include coating the outside of the toner particles. In this coating step, a separate external additive, for example, an inorganic powder including silica, titanium dioxide, or a mixture thereof, may be coated on the toner particle surface. After adding the external additive to the particles, it may proceed by a method of high-speed stirring. The silica, which is known to be usable in the polymerized toner, may be used without particular limitation. As the inorganic powder applicable in the coating step has been described above, a detailed description thereof will be omitted.

According to one embodiment of the present invention, the method for preparing a polymerized toner of the present invention further comprises the step of adding one or more additives selected from the group consisting of a reaction initiator, a crosslinking agent, a lubricant, a molecular weight regulator, and a coupling agent to the mixture. may include Specific examples and preferred content ranges of these additives are as described above.

The polymerized toner prepared according to the present invention has excellent physical properties capable of realizing a uniform image with high image density and excellent transfer efficiency with a narrow particle size distribution. When the polymerized toner of the present invention is used, the transfer efficiency is 95% or more, and the image density on the printing paper is 1.35 or more, which can have very good physical properties. As described above, by having a high transfer efficiency of 95% or more, there is an advantage in that a high image density can be realized with a small amount of consumption. Therefore, the polymerized toner of the present invention can be effectively applied to fields such as electrophotographic development and printing that require the realization of high and uniform images, and it is expected that excellent quality printing results can be obtained by using the polymerized toner.

Hereinafter, a method for preparing a polymerized toner according to a specific embodiment of the present invention and a polymerized toner prepared accordingly will be described in detail with reference to Examples to help the understanding of the present invention. However, the embodiments according to the present invention can be modified in various other forms, which are presented as an example of the invention, thereby not limiting the scope of the invention, and embodiments within the scope of the invention Various modifications are possible for The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

<Example 1> Preparation of polymerized toner

(1) Preparation of polymerized toner

686 g of 0.1 M aqueous sodium phosphate solution and 100 g of 1M calcium chloride were mixed in 500 g of water and stirred at a reaction temperature of 70° C. for 20 minutes to prepare an aqueous dispersion in which calcium phosphate crystals were precipitated. The content of calcium phosphate in the aqueous dispersion was 3 parts by weight based on 100 parts by weight of the following mixture.

Monomer for binder resin of 160 g of styrene, 36 g of n-butyl acrylate, and 4 g of acrylic acid, 4 g of allyl methacrylate as a crosslinking agent, 0.4 g of n-dodecyl mercaptan as a molecular weight modifier, 3 g of a pigment dispersant, and a weight 4 g of a styrene-acrylic polymer charge control agent (Styrene/2EHA/anionic functional monomer copolymer, FCA 1001 NS, Fujikura Kasei) containing a sulfonic acid group having an average molecular weight of 16,500 is mixed and fully dissolved in a 1L container, and the cyan pigment ( PV Fast Yellow H4G, Clariant Corporation) 10 g and TiO ₂ (R902+, Chemours) 2 g were added, and the cyan pigment was impregnated in the monomer. Then, 70 g of 0.3 mm zirconium beads were added and stirred at a speed of 10,000 rpm 60 After milling for minutes, the beads were removed using 200 mesh.

To the mixture from which the beads were removed, 20 g of paraffin wax (Fisher) was further added and stirred to completely dissolve the wax in the mixture, and 5 g of an azo nitrile-based initiator (Azo nitrile; V65, Waco Chemical) was added, and A mixture was prepared by further stirring for 5 minutes. At this time, the weight of the mixture was 246.4 g.

Then, the mixture was added to the aqueous dispersion, and a shearing force was applied using a homogenizer at a speed of 13,000 rpm to disperse the mixture in the aqueous dispersion in the form of fine droplets to homogenize. The mixture dispersed in the aqueous dispersion in the form of fine droplets through the homogenization was reacted at 60 °C for 10 hours while stirring at 200 rpm with a paddle-type stirrer, and then heated to 90 °C and further reacted for 3 hours to be included in the slurry A polymerized toner was prepared in the form of

(2) Toner particle cleaning and drying

Hydrochloric acid was added to the slurry containing the polymerized toner to adjust the pH to 2 or less, and calcium phosphate was dissolved. Then, after removing water using a filtration device, dilute by adding distilled water twice the total weight, applying shear force with a homogenizer to homogenize, and then centrifuge device (Beckman J2-21M, Rotor JA-14) was centrifuged at 3,000 rpm for 15 minutes. These dilution, homogenization, and centrifugation processes were repeated three times to remove calcium phosphate and other impurities from the toner surface.

After moisture was finally removed through filtration, 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 μm, and a ratio (standard deviation) of the volume average particle diameter to the number average particle diameter was 1.26. At this time, the volume average particle diameter of the core was measured using a Coulter counter (Multisizer 3, Beckman coulter).

(3) External additive coating

After adding 2 parts by weight of silica based on 100 parts by weight of the polymerized toner core using a Henschel mixer, the mixture was stirred at a high speed of 5,000 rpm for 7 minutes to coat the surface of the polymerized toner core with an external additive.

<Example 2>

A polymerized toner was prepared in the same manner as in Example 1, except that the cyan pigment was used in an amount of 13 g.

<Example 3>

A polymerized toner was prepared in the same manner as in Example 1, except that TiO ₂ was used in an amount of 1 g.

<Example 4>

A polymerized toner was prepared in the same manner as in Example 1, except that TiO ₂ was used in an amount of 3 g.

<Comparative Example 1>

A polymerized toner was prepared in the same manner as in Example 1, except that TiO ₂ was not used.

<Comparative Example 2>

A polymerized toner was prepared in the same manner as in Example 2, except that TiO ₂ was not used.

<Comparative Example 3>

A polymerized toner was prepared in the same manner as in Example 1, except that TiO ₂ had an average particle diameter of 800 nm.

<Comparative Example 4>

A polymerized toner was prepared in the same manner as in Example 2, except that TiO ₂ had an average particle diameter of 800 nm.

<Test Example 1>

The polymerized toners prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated for physical properties as follows.

(1) toner transfer efficiency

After each of the polymerized toners prepared according to Examples 1 to 4 and Comparative Examples 1 to 4 were filled in the supply part of the laser printer (HP4600, manufacturer: Hewlett-Packard) cartridge, the weight of the entire supply part was measured. After 1,000 sheets of a 19 cm wide and 1.5 cm long rectangle were printed on A4 paper, the weight of the feeder was measured again, and the toner consumption was calculated as in Equation 1 below.

In addition, the weight of the supply unit and the detachable drum unit was measured before printing and after printing, respectively, and the amount of toner wasted without paper transfer was calculated as in Equation 2 below.

After calculating the amount of toner consumed and wasted as described above, the transfer efficiency was calculated as shown in Equation 3 below.

(2) Image density measurement

After printing the entire surface on A4 size paper with a laser printer (HP2600, manufacturer: Hewlett-Packard), measure the image density at 4 corners and 1 center of the printing paper using an image density meter (RD918, acbath) and measure the average value was taken.

(3) Transmission Electron Microscopy Analysis

In the polymerized toners prepared according to Examples 1 to 4 and Comparative Examples 1 to 4, the size of the yellow pigment aggregate was measured by an image analysis method.

Table 1 below shows the test evaluation conditions and evaluation results accordingly.

Evaluation conditions
Evaluation results
Cyan Pigment Weight
TiO ₂ parts by weight
TiO ₂ size
Transfer efficiency (%)
image density
Example 1
10g
2
400nm
97
1.41
Example 2
13g
2
400nm
96
1.42
Example 3
10g
One
400nm
96
1.37
Example 4
10g
3
400nm
97
1.36
Comparative Example 1
10g
-
-
82
1.25
Comparative Example 2
13g
-
-
83
1.27
Comparative Example 3
10g
2
800nm
87
1.31
Comparative Example 4
13g
2
800nm
88
1.33

As shown in Table 1, the polymerized toners of Examples 1 to 4 prepared according to the present invention greatly improved the transfer efficiency to 96% or more, and it was confirmed that the image density was increased from at least 1.36 to 1.42. On the other hand, in the case of the polymerized toners of Comparative Examples 1 to 4, the transfer efficiency was very low compared to the polymerized toner of the present invention. In particular, the image density was less than 1.35, so a clear and uniform image was not realized when electrophotographic development was applied. It can be seen that there may be problems that do not exist.

As described above in detail a specific part of the present invention, for those of ordinary skill in the art, this specific description is only a preferred embodiment, and it is clear that the scope of the present invention is not limited thereto. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (13)

A polymerized toner comprising:
a binder resin, a pigment, a dispersant, TiO ₂ , a charge control agent, and toner particles comprising a wax,
Polymerized toner, characterized in that the average particle diameter of TiO ₂ in the toner particles is 500 nm or less. The method of claim 1,
The toner particles contain 50 to 95% by weight of a binder resin, 1 to 20% by weight of a pigment, 0.1 to 20% by weight of a pigment dispersant, 0.1 to 2% by weight of TiO ₂ , 0.1 to 5% by weight of a charge control agent, and 0.1 to 30% by weight of a wax Polymerized toner comprising: The method of claim 1,
The polymerized toner, characterized in that the binder resin is a polymer or copolymer of a styrene-based monomer, an acrylate-based monomer, a methacrylate-based monomer, a diene-based monomer, an acidic olefin-based monomer, a basic olefin-based monomer, or a mixture thereof. The method of claim 1,
The binder resin is (a) a styrenic monomer; and (b) a polymer or copolymer of at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer, and a diene-based monomer. The method of claim 1,
The binder resin is a styrene-based monomer of (a), (b) at least one monomer selected from the group consisting of an acrylate-based monomer, a methacrylate-based monomer and a diene-based monomer, and (c) an acidic olefin-based monomer and basic Polymerized toner, characterized in that it is a polymer or copolymer of a monomer obtained by polymerizing one or more monomers selected from the group consisting of olefinic monomers. The method of claim 1,
Polymerized toner, characterized in that the toner particles further include at least one additive selected from the group consisting of a reaction initiator, a crosslinking agent, a molecular weight control agent, a lubricant, and a coupling agent. The method of claim 1,
The polymerized toner, characterized in that the toner particles have an average particle diameter of 4 to 10 μm. 8. A method for preparing the polymerized toner according to any one of claims 1 to 7, comprising toner particles, characterized in that it is prepared according to a process comprising the steps of:
(S1) preparing an aqueous dispersion containing a dispersant;
(S2) preparing a mixture by mixing a binder resin, a pigment, TiO ₂ , a charge control agent and a wax; and
(S3) preparing toner particles by adding the mixture prepared in step (S2) to the aqueous dispersion prepared in step (S1) and then performing suspension polymerization. 9. The method of claim 8,
In the step (S2), after adding the pigment, milling with a bead mill at a stirring speed of 8,000 to 20,000 rpm for 10 to 120 min is performed. 10. The method of claim 9,
The milling process is a method for producing a polymerized toner, characterized in that it is performed by adding 20 to 50 parts by weight of beads based on 100 parts by weight of the mixture of step (S2). 9. The method of claim 8,
The method for producing a polymerized toner, characterized in that the suspension polymerization in step (S3) is performed at 60 to 90° C. for 8 to 20 hours. 9. The method of claim 8,
(1) removing the dispersant; and (2) drying the toner particles. 9. The method of claim 8,
The method for producing a polymerized toner, characterized in that it further comprises the step of coating the outside of the toner particles prepared in step (S3).