Patent Application
20080076057
Reference will now be made in detail to the embodiments of the present general inventive concept. The embodiments are described below in order to explain the present general inventive concept. The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the embodiments of the invention and are merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
According to an exemplary embodiment of the present general inventive concept, a method of preparing a latex for a toner composition may include preparing a monomer solution by dissolving a polyester-based monomer in an organic solvent and adding a vinyl-based monomer thereto, preparing an aqueous macromonomer solution by dissolving a macromonomer in water, preparing a solution in which the monomers and macromonomer are emulsified by mixing the monomer solution and the aqueous macromonomer solution, and polymerizing the monomers by adding a hydrophilic polymerization initiator to the emulsified solution.
In the method of preparing a latex for a toner composition according to the above exemplary embodiment, the polyester-based monomer is first dissolved in the organic solvent.
Any polyester-based monomer usable in polymerization may be used as the polyester-based monomer usable in the above exemplary embodiment. For example, a polyester-based resin may be used as the polyester-based monomer. For this, a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A, which are used as an alcohol component, and a terephthalic acid, a trimellitic anhydride, a fumaric acid, or a succinic acid derivative, which are used as an acid component, can be polymerized to obtain the polyester-based resin.
Among polyester-based monomers, a polyethylene terephthalate (PET) monomer may be used in the above exemplary embodiment. The PET monomer has a molecular weight of approximately 1,000 to approximately 100,000 and a glass transition temperature of approximately 40° C. to approximately 80° C.
As the organic solvent usable in the above exemplary embodiment of the present general inventive concept, any organic solvent which is capable of dissolving the polyester-based monomer, such as, the PET monomer, may be used. The organic solvent may be, for example, one of methylene chloride, ethyl acetate, and a mixture thereof. Methylene chloride may also be used as the organic solvent.
The polyester-based monomer is dissolved in the organic solvent, the vinyl-based monomer is then added thereto, and the monomers are mixed together.
A monomer which is capable of being polymerized and has a vinyl group may be used as the vinyl-based monomer. The vinyl-based monomer may be selected from the group consisting of a styrene monomer, an acrylate monomer, and a methacrylate monomer.
A content of the polyester-based monomer dissolved in the organic solvent may be approximately 0.1% to approximately 50% by weight based on the weight of the vinyl-based monomer.
If a toner particle is prepared in a form of hybrid by polymerizing the polyester-based monomer together with the vinyl-based monomer as described above, the toner particle exhibits a high gloss and a high particle uniformity which are advantages of the polyester-based monomer. Additionally, the composition of the vinyl-based monomer, particularly, a styrene-acryl-based resin is changed, and thus, a fixing temperature and a toner structure can be controlled. In other words, when the polyester-based monomer and the vinyl-based monomer are used according to the above exemplary embodiment, the benefits of each can be simultaneously implemented in the toner.
After the polyester-based monomer and the vinyl-based monomer are dissolved in the organic solvent, a macromonomer is dissolved in water separately from the dissolution of the monomers, and an aqueous macromonomer solution is then prepared.
The macromonomer has amphiphilic (hydrophobic/hydrophilic) properties, and may include a polymer or an oligomer which has a polymerizable functional group at one terminal end. A hydrophilic portion which is chemically bonded to a particle surface of the macromonomer enables excellent long-term stability of particles to be obtained by steric stabilization. Additionally, the hydrophilic portion can control a particle size of a toner latex according to the amount or molecular weight of the macromonomer to be inserted.
In addition, the macromonomer can be used as a monomer to be polymerized during latex polymerization.
Furthermore, the macromonomer serves as an emulsifier used in emulsion polymerization. Accordingly, in the method of preparing a latex, the monomer can be emulsified using the macromonomer instead of the emulsifier, for example, a surfactant which is mainly used as an emulsifier.
Therefore, a conventional emulsifier washing process can be simplified. If the surfactant is used as the emulsifier, a large amount of wastewater can be generated by removing the surfactant, and the wastewater thus generated may have a negative effect on the environment. Accordingly, a process required for removing the emulsifier is simplified to reduce a manufacturing cost of the toner and the amount of wastewater to be discharged, so that a toner can be prepared using an environmentally friendly preparation method. Additionally, problems caused by the emulsifier, such as sensitivity to humidity, low frictional electrification, decrease in dielectric constant, toner aging, and a decrease in toner flexibility, can be removed, and toner storage can be improved.
The macromonomer usable in the above exemplary embodiment may be a compound in which a chain of a compound, such as polyethylene oxide or polyethylene glycol (PEG), is modified or a vinyl group is introduced. Examples of the macromonomer may include polyethylene glycol-methacrylate, polyethylene glycol-ethyl ether methacrylate, polyethylene glycol-dimethacrylate, polyethylene glycol-modified urethane, and polyethylene glycol-modified polyester.
After the aqueous macromonomer solution is prepared, a monomer solution in which the polyester-based monomer and vinyl-based monomer are dispersed is mixed with the aqueous macromonomer solution, to obtain a solution in which the monomers are emulsified in the aqueous macromonomer solution.
In order to initiate monomer polymerization, a hydrophilic polymerization initiator is added to the emulsified solution. Any material capable of initiating polymerization in an aqueous solution may be used as the hydrophilic polymerization initiator, for example, potassium persulfate may be used.
According to another exemplary embodiment of the present general inventive concept, a method of preparing a toner composition may include preparing a latex according to the method of preparing a latex for a toner composition as described above, and adding a wax, a colorant, an emulsifier, and a flocculant to the polymerized latex composition.
The wax is used as a release agent in order to prevent toner offset. Examples of the wax usable in this exemplary embodiment may include polyethylene, polypropylene, ester, a carnauba wax, or the like. However, the present general inventive concept is not necessarily limited thereto, and other suitable waxes may be used.
Colorants embody the colors of toner particles and can be divided into dye-based colorants and pigment-based colorants. Generally, any colorant which is widely used may be used as the colorant of this exemplary embodiment. For example, a pigment-based colorant, which has excellent thermal stability and light resistance, can be used as the colorant.
Examples of pigment-based colorants usable in the toner composition according to this exemplary embodiment, may include azo-based pigments, phthalocyanine-based pigments, basic dye-based pigments, quinacridone-based pigments, dioxazine-based pigments, condensed azo-based pigments, chromates, ferrocyanides, oxides, sulfides, selenides, sulfates, silicates, carbonates, phosphates, metal powder, and carbon black, but the present general inventive concept is not necessarily limited thereto.
Since the pigment-based colorant is generally insoluble in water, the pigment-based colorant has low solubility in the prepared soluble latex solution. Accordingly, an additive may be needed to dissolve the colorant, and thus the colorant can be mixed with the macromonomer as an emulsifier in order to disperse the colorant, the mixture may be dispersed and added to the latex.
The flocculant is used to flocculate emulsified particles, and magnesium chloride may be used as the flocculant.
Additionally, an external additive, such as silica, can be added to the dried toner particles to control the charge amount and other properties. Finally, a dry toner is prepared.
Hereinafter, in Example 1, a toner composition is prepared using a macromonomer instead of an emulsifier when preparing an emulsion polymerized toner using a polyester-based monomer and a vinyl-based monomer according to an exemplary embodiment of the present general inventive concept. In Examples 2 to 4, toner compositions are prepared using a macromonomer as an emulsifier when preparing an emulsion polymerized toner using a latex. It will be apparent to those skilled in the art that the description of the exemplary embodiments of the present general inventive concept is intended to be illustrative of the preparation of a latex for a toner composition and a toner composition, but does not limit the preparation method performed in this manner.
0.5 g of polyethylene terephthalate (PET) was dissolved in 5 ml of a methylene chloride solvent, and then the obtained solution was mixed with 5 g of a styrene monomer to obtain a homogeneous solution. Additionally, 0.5 g of poly(ethylene glycol)-ethyl ether methacrylate (PEG-EEM, manufactured by Aldrich Chemical Co.) as a macromonomer was dissolved in 100 g of distilled water to obtain a mixed solution.
The homogeneous solution and the mixed solution as prepared above were strongly agitated using ultrasonic waves to obtain a droplet in which the PET and styrene monomer were stabilized in an aqueous liquid phase. After the resulting mixture was heated to 70° C. while pursing with nitrogen gas, 0.1 g of potassium persulfate as a hydrophilic polymerization initiator was added thereto, and then the mixture was stirred at 350 rpm for 24 hours to obtain a hybrid latex. The polymerized latex had an average particle size of approximately 500 nm. The polymerized latex was then dried and examined by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) techniques. The results indicated that the hybrid latex thus prepared had excellent thermal stability.
40 g of deionized water and 25 g of the obtained hybrid latex were added to a reactor, and then the mixture was stirred at 300 rpm. 30 g of a black pigment solution and 3 g of MgCl2, which were dispersed by the macromonomer, were added thereto while stirring the mixture. The pH of the reaction solution was adjusted to 10, and then the solution was gradually heated to 95° C. When the toner had a volume average particle size of approximately 6 μm after the reaction solution was continuously stirred at 95° C., 4 g of NaCl was dissolved in 10 g of distilled water, and the solution was added thereto. Subsequently, the resulting mixture was heated for 4 hours and shaped into particles, followed by cooling and filtration to obtain toner particles.
Toner particles of a desirable size and shape were prepared, and then cooled below Tg. Next, the toner particles were filtered, separated, and dried. External additives, such as silica, were added externally to the dried toner particles to control the charge amount and other properties. By this means, a final dry toner for an electrophotographic image forming apparatus was prepared.
As described above, the monomers could be emulsified and polymerized using the macromonomer instead of an emulsifier, and accordingly, it was possible to prepare a toner composition having advantages of the PET and styrene resin without a separate emulsifier washing process.
0.5 g of polyethylene terephthalate (PET) was dissolved in 5 ml of a methylene chloride solvent, and then the obtained solution was mixed with 5 g of a styrene monomer to obtain a homogeneous solution. Additionally, 0.25 g of sodium dodecyl sulfate (SDS) as an emulsifier was dissolved in 100 g of distilled water to obtain a mixed solution.
The homogeneous solution and the mixed solution as prepared above were strongly agitated using ultrasonic waves to obtain a droplet in which the PET and styrene monomer were stabilized in an aqueous liquid phase. After the resulting mixture was heated to 70° C. while pursing with nitrogen gas, 0.1 g of potassium persulfate as a hydrophilic polymerization initiator was added thereto, and then the mixture was stirred at 350 rpm for 24 hours to obtain a hybrid latex. The polymerized latex had an average particle size of approximately 300 nm. The polymerized latex was then dried and examined by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) techniques. The results indicated that the hybrid latex thus prepared had excellent thermal stability.
40 g of deionized water and 25 g of the obtained hybrid latex were added to a reactor, and then the mixture was stirred at 300 rpm. 30 g of a black pigment solution and 3 g of MgCl2, which were dispersed by the macromonomer, were added thereto while stirring the mixture. The pH of the reaction solution was adjusted to 10, and then the solution was gradually heated to 95° C. When the toner had a volume average particle size of approximately 6 μm after the reaction solution was continuously stirred at 95° C., 4 g of NaCl was dissolved in 10 g of distilled water, and the solution was added thereto. Subsequently, the resulting mixture was heated for 4 hours and shaped into particles, followed by cooling and filtration to obtain toner particles.
Toner particles of a desirable size and shape were prepared, and then cooled below Tg. Next, the toner particles were filtered, separated, and dried. External additives, such as silica, were added externally to the dried toner particles to control the charge amount and other properties. By this means, a final dry toner for an electrophotographic image forming apparatus was prepared.
When preparing a latex as described above, a macromonomer was used instead of an emulsifier, such as a surfactant, in order to dissolve the water-insoluble colorant in the water-soluble latex, and accordingly, it was possible to prepare a toner composition having advantages of the PET and styrene resin without a separate emulsifier washing process.
0.5 g of polyethylene terephthalate (PET) was dissolved in 5 ml of a methylene chloride solvent, and then the obtained solution was mixed with 5 g of a styrene monomer to obtain a homogeneous solution. Additionally, 0.8 g of sodium dodecyl sulfate (SDS) as an emulsifier was dissolved in 200 g of distilled water to obtain a mixed solution.
The homogeneous solution and the mixed solution as prepared above were strongly agitated using ultrasonic waves to obtain a droplet in which the PET and styrene monomer were stabilized in an aqueous liquid phase. After the resulting mixture was heated to 70° C. while pursing with nitrogen gas, 0.1 g of potassium persulfate as a hydrophilic polymerization initiator was added thereto, and then the mixture was stirred at 350 rpm for 24 hours to obtain a hybrid latex. The polymerized latex had an average particle size of approximately 80 nm. The polymerized latex was then dried and examined by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) techniques. The results indicated that the hybrid latex thus prepared had excellent thermal stability.
40 g of deionized water and 25 g of the obtained hybrid latex were added to a reactor, and then the mixture was stirred at 300 rpm. 30 g of a black pigment solution and 3 g of MgCl2, which were dispersed by the macromonomer, were added thereto while stirring the mixture. The pH of the reaction solution was adjusted to 10, and then the solution was gradually heated to 95° C. When the toner had a volume average particle size of approximately 6 μm after the reaction solution was continuously stirred at 95° C., 4 g of NaCl was dissolved in 10 g of distilled water, and the solution was added thereto. Subsequently, the resulting mixture was heated for 4 hours and shaped into particles, followed by cooling and filtration to obtain toner particles.
Toner particles of a desirable size and shape were prepared, and then cooled below Tg. Next, the toner particles were filtered, separated, and dried. External additives, such as silica, were added externally to the dried toner particles to control the charge amount and other properties. By this means, a final dry toner for an electrophotographic image forming apparatus was prepared.
When preparing a latex as described above a macromonomer was used instead of an emulsifier, such as a surfactant, in order to dissolve the water-insoluble colorant in the water-soluble latex, and accordingly, it was possible to prepare a toner composition having advantages of the PET and styrene resin without a separate emulsifier washing process.
A toner composition was prepared in the same manner as in Example 3, except that a mixture of a styrene monomer, an n-butyl acrylate monomer, and a methacrylic acid monomer (the total weight of the mixture was 10 g, and the weight ratio was 7:2:1 to 6.5:3.0:0.5, respectively) was used instead of the styrene monomer. In the flocculation reaction, the toner had a volume average particle size of approximately 7 μm and was shaped into particles, followed by cooling and filtration to obtain toner particles.
When preparing a latex as described above, a macromonomer was used instead of an emulsifier, such as a surfactant, in order to dissolve the water-insoluble colorant in the water-soluble latex, and accordingly, it was possible to prepare a toner composition having advantages of the PET and styrene resin without a separate emulsifier washing process.
As described above, according to exemplary embodiments of the present general inventive concept, the latex for a toner composition having advantages of polyester-based and vinyl-based monomers can be prepared without using an emulsifier. Therefore, it is not necessary to wash the emulsifier, and thus there is no decrease in toner performance due to the remaining emulsifier. Accordingly, the latex for a toner composition and the toner composition prepared using the latex can be prepared using simpler and more environmentally friendly processes.
Additionally, according to the present general inventive concept, it is possible to obtain a toner composition which exhibits a high gloss, an excellent durability, a low-temperature fixing property, and a controllability of a structure of toner.
Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-93511 | Sep 2006 | KR | national |
