KR20090058945A - Toner particle and electrophotographic image forming device comprising the same - Google Patents

Abstract

Toner particles, an electrostatic latent image developer containing the toner particles and an electrophotographic image forming device comprising the same are provided to determine whether the prints are a copy or not with naked eyes easily because invisible image is changed into visible image when excited with electromagnetic radiation having energy less than infrared rays unlike conventional image. Toner particles comprise a binder resin and an anti-stokes phosphor. The anti-stokes phosphor is not determined by naked eyes but can form invisible image by radiating visible rays through excitation by infrared rays. The phosphor is at least one kind selected from the group consisting of YF3:Yb+Er, YF3:Yb+Tm, LiYF4:Yb+Tm, LiYF4:Yb+Er, NaYF4:Yb+Tm, NaYF4:Yb+Er, BaFCl:Yb+Er, ZrF4:Er and ZrF4:Tm.

Description

Toner particles and electrophotographic image forming device comprising the same

The present invention relates to toner particles and an electrophotographic image forming apparatus employing the same. More particularly, the present invention relates to toner particles including an anti-stock phosphor, and toner particles that can easily be visually judged as a copy of a printed matter and an electrophotographic employing the same. And an image forming apparatus for the same.

Recently, printing technology using electrophotographic technology has been greatly developed. In addition, related technologies such as color copying technology or technology for improving the sharpness of printed images have also been developed. The development of printing technology using such electrophotographic technology has enabled the production of copies that are difficult to distinguish from the original. Therefore, as a method for preventing forgery of printed matter printed using electrophotographic technology, a technique for facilitating differentiation between an original and a copy is required.

In this regard, various techniques have been developed in the past to prevent forgery. Japanese Laid-Open Patent Publication No. 1995-271081 discloses a toner containing an infrared absorbing material in a toner for forming a color image as a counterfeit prevention. When the toner is used, it is possible to visually identify whether the object is a counterfeit or not by irradiating infrared rays on an object such as a bill.

Japanese Laid-Open Patent Publication No. 2002-072537 discloses a toner containing a binder resin and DNA. In this case, however, the presence or absence of DNA in the print must be identified to distinguish between the copy and the original. Therefore, there is a disadvantage that this identification is expensive and the process is complicated, difficult and time consuming.

Japanese Patent Application Laid-Open No. 2002-211102 discloses a technique for easily distinguishing an original from a copy or a counterfeit using pearl ink, and Japanese Patent Application Laid-Open No. 2003-186377 uses a hologram print to provide an anti-counterfeiting effect. The technique shown is disclosed. These techniques are effective in preventing forgery, but the problem is that the materials used in these techniques are expensive and special printing techniques are required.

Therefore, there is still a need to develop a toner that can easily determine at a low cost whether or not to copy a printed matter by solving the problems of the conventional technologies.

The first technical problem to be achieved by the present invention is to provide toner particles which can be easily identified by visual observation at low cost without special equipment for copying of printed matter.

The second technical problem to be achieved by the present invention is to provide an electrostatic latent image developer comprising the toner particles.

A third technical problem to be achieved by the present invention is to provide an electrophotographic image forming apparatus employing the toner particles or the electrostatic latent image developer.

In order to achieve the first technical problem, the present invention

A binder resin and a visible light emitting anti-stokes phosphor, which is invisible to the naked eye but is excited by infrared light to emit visible light, thereby invisible image Provided are toner particles that can be formed.

In order to achieve the second technical problem, the present invention

Toner particles according to the above; And

An electrostatic latent image developer comprising a carrier is provided.

In order to achieve the third technical problem, the present invention

An electrophotographic image forming apparatus employing the toner particles or the electrostatic latent image developer according to the above is provided.

Since the toner particles of the present invention include visible light emitting anti-stock phosphors, invisible images are visible to the naked eye when excited by electromagnetic rays having energy below infrared rays, unlike images formed by conventional general toners. The image is changed into a visible image so that it is easy to visually determine whether a printed matter is a copy.

Hereinafter, toner particles according to a preferred embodiment of the present invention will be described in more detail.

Toner particles according to an embodiment of the present invention comprises a binder resin and a visible light emitting anti-stokes phosphor (anti-stokes phosphor), which is not visible to the naked eye, but is excited by infrared light to be visible By emitting light, an invisible image is formed.

The principle of allowing the toner particles to visually determine whether a toner is a copy is described in more detail below, but the description is not intended to limit the scope of the present invention but to help the understanding of the present invention.

Copiers or scanners use halogen lamps or xenon lamps as light sources. The emission spectra of halogen lamps vary in intensity of emission peaks depending on the temperature of the lamp, but are generally distributed over 500 to 2500 nm and exhibit maximum intensity at 900 to 1400 nm. The emission spectrum of the xenon lamp is similar to that of the halogen lamp, but there are a plurality of emission peaks. Halogen lamps and xenon lamps exhibit high-intensity light emission in the vicinity of 830-880 nm, which is an infrared region. When the image formed on the print includes phosphors that absorb infrared rays and emit visible light, the infrared rays emitted by the halogen or xenon lamps of the copier are absorbed by the phosphors contained in the image and then converted into visible light and emitted as reflected light. do. In addition to the reflected light reflected by the visible light incident on the printed matter from the lamp, the reflected light generated by converting the infrared rays incident on the printed matter is further generated. As a result, the image recognized by the image sensor of the copier which recognizes the reflected light is different from that of the printed matter. In other words, the image formed on the copy is different from the image formed on the original.

The anti-stokes phosphor is a phosphor that absorbs electromagnetic radiation having low energy and emits electromagnetic radiation having high energy, and is, for example, a phosphor that absorbs infrared rays and emits visible light. The phosphor according to one embodiment of the present invention is preferably excited by infrared rays, particularly a wavelength in the range of 830 to 880 nm. However, the electromagnetic beam used to excite the phosphor is not limited to infrared rays and is not limited as long as it can emit visible light by exciting the anti-Stokes phosphor as an electromagnetic ray having a lower energy or longer wavelength than visible light. Do not.

The visible light emitted by the phosphor is not particularly limited in wavelength and may be used as long as it is not white light. For example, blue light, green light, red light, or the like can be used.

Therefore, the phosphor according to the embodiment of the present invention absorbs electromagnetic rays such as infrared rays having a longer wavelength than visible light and emits visible light, and may be, for example, a blue light emitting phosphor, a green light emitting phosphor, a red light emitting phosphor, or the like. have.

Phosphor according to another embodiment of the present invention is YF ₃ : Yb + Er, YF ₃ : Yb + Tm, LiYF ₄ : Yb + Tm, LiYF ₄ : Yb + Er, NaYF ₄ : Yb + Tm, NaYF ₄ : Yb + Preference is given to compounds derived from the general formula represented by Er, BaFCl: Yb + Er, ZrF ₄ : Er, ZrF ₄ : Tm. If the compound derived from the said general formula emits visible light, it will not be limited by a specific composition. For example, Yb and doped with Er YF _3, Yb and doped YF the Tm _3, Yb and LiYF _4, doped with Tm Yb and Er a LiYF _4, Yb, and Tm a NaYF _4, Yb doped with doping in and Er is the NaYF _4, such as Yb and Er of BaFCl, a ZrF doped with a ZrF _4, doped with Er or Tm is doped with ₄ doped with. As the phosphor that satisfies the general formula, any phosphor that converts infrared rays into visible light may be used regardless of the specific content of metal ions present in the crystal structure.

According to another embodiment of the present invention, the phosphor content is preferably 0.05 to 10% by weight based on the total weight of the toner particles. If the phosphor content is less than 0.05% by weight it is not easy to determine whether the radiation or not, if the phosphor content is more than 10% by weight there is no difference in the intensity of the visible light emitted. It is preferable that the volume average particle diameter of the said fluorescent substance is 0.1-1.0 micrometer. If out of the above range, there is a problem in uniform particle growth in toner production.

In the toner particles, the phosphor may be used as such, but may be used as a phosphor master batch in which phosphor is dispersed in a resin. By using this as a master batch form, the phosphor can be uniformly distributed in the toner particles.

Phosphor master batch refers to a resin composition in which the phosphor is evenly dispersed, which kneads the phosphor and the resin under high temperature and high pressure, or dissolves the phosphor by dissolving the resin in a solvent and adding the phosphor to the formed solution and applying a high shear force. It is manufactured by the method. In the latter case, the solvent must be removed before the toner is used. When used as a master batch, the phosphors are evenly dispersed compared to simple mixing, and the peculiarity is that the resin used in the master batch is not completely dissolved in the solvent, although the master batch is ground to a very small size during dispersion. That is, no matter how small the particles are, when applied to the present step, the structure in which the surface of the particles is covered with resin can be maintained. The content of the phosphor in the phosphor master batch used in the present invention is preferably 1 to 60% by weight, more preferably 5 to 30% by weight.

The binder resin is not particularly limited as long as it is a known binder resin used in the art. Therefore, styrene resins, such as polystyrene resin and styrene-acrylic acid ester copolymer resin; Saturated or unsaturated polyester resins; Epoxy resins; Phenolic resins; Xylene resin; Vinyl chloride resins; Polyolefin resin and the like can be used. It is preferable to use styrene resin, polyester resin, epoxy resin, and olefin resin among the said resin, and it is also possible to use these resin individually or in mixture of 2 or more types. The content of the binder resin contained in the toner particles is preferably 50 to 99% by weight based on the total weight of the toner.

According to another embodiment of the present invention, the toner particles may further include additives such as colorants, mold release agents, charge control agents and external additives.

The colorant used in the toner particles may be a pigment or dye commonly used in the art, for example, cyan pigment, magenta pigment, yellow pigment, black pigment, white pigment, or a mixture thereof. It may be appropriately selected and used in consideration of hue, saturation, lightness, weather resistance, transparency, affinity with toner resin, and the like. The kind of the coloring agent is not particularly limited as long as it is used in the art. For example, in the case of toner particles including a red light-emitting phosphor and a yellow pigment, the original is a yellow image, but copying such an original forms an orange image in which yellow and red are mixed on the copy, so that copying can be easily determined.

When the colorant is contained in an excessive amount, the elasticity of the resin composition may be increased, thereby making it difficult to form fine particles or the particle size may be widened. When the colorant is contained in a small amount, the colorant of the toner may be lowered, resulting in insufficient color expression during printing. Preferably the content of the colorant is 2 to 15% by weight, more preferably 4 to 12% by weight based on the total weight of the toner particles, but is not necessarily limited to this range, and an appropriate amount may be selected according to the use.

The pigmented pigment in the toner particles can be used as such, but can be used as a pigmented master batch in which the pigmented pigment is dispersed in the resin. By using it as a master batch form in this way, surface exposure of a coloring agent can be suppressed and the charging performance of a toner particle can be improved. The pigment content in the pigment pigment master batch is preferably 10 to 60% by weight, more preferably 20 to 40% by weight, but is not necessarily limited thereto, and an appropriate amount may be selected according to the use.

The release agent is an additive capable of improving fixability of a toner image, and may include montan wax, rice wax, cancan wax, ester wax, carnauba wax, polyethylene wax, polypropylene wax, bead wax, paraffin wax, and mixtures thereof. And the like can be used. If the content of the release agent is too low, it is difficult to fix the toner particles without using oil. If the content of the release agent is too high, aggregation of the toner may occur during long-term storage, which is not preferable.

The content of the release agent included in the toner particles is preferably 0.1 to 30% by weight based on the total weight of the toner particles, more preferably 1 to 10% by weight, but is not necessarily limited thereto, and an appropriate amount is selected according to the use. Can be.

The charge control agent may be appropriately selected and used according to the charge to be applied to the final toner, and a positive charge control agent, a negative charge control agent, a mixture thereof, and the like may be used.

In the present invention, when the content of the charge control agent is low, there may be a problem that the charging speed of the toner is lowered and the amount of charge is reduced, and when the content is excessive, the charge may be excessively increased, causing distortion in the image. The content of the charge control agent is not particularly limited, but is preferably 0.1 to 20% by weight, more preferably 0.1 to 8% by weight, most preferably 0.3 to 5% by weight based on the total weight of the toner.

In addition to the additives, the toner particles may be coated with an external additive such as a fluidizing agent, which is a very small organic or inorganic particle, coated on the surface of the toner particles. The external additive serves to improve the fluidity of the particles to be used as the toner, or to control charging characteristics such as the charging amount and the charging speed.

When the external additive is added, the toner particles and the external additive may be mixed with a Henschel mixer, a V mixer, a cyclo mixer, or the like. The content of the external additive is not particularly limited and may be appropriately selected depending on the use, but is preferably in the range of 0.01 to 5 parts by weight based on 100 parts by weight of the binder resin.

The toner particles according to the exemplary embodiment of the present invention are not particularly limited in the manufacturing method, and all known methods known in the art may be used. For example, the kneading grinding method of kneading, grinding and classifying binder resin, a mold release agent, a charge control agent, etc .; A method of changing the shape of the particles produced by the kneading milling method using mechanical impact or thermal energy; An emulsion polymerization flocculation method of emulsion polymerizing a polymerizable monomer of a binder resin, mixing the resulting dispersion with another dispersion in which a release agent, a charge control agent, and the like are dispersed, followed by flocculation, heating, and fusing to obtain a toner; Suspension polymerization method in which a solution such as a polymerizable monomer, a releasing agent, a charge control agent or the like for obtaining a binder resin is suspended in an aqueous solvent and polymerized; A solution suspension method of suspending a solution such as a binder resin, a releasing agent, a charge control agent, and the like in an aqueous solvent may be used. It is also possible to use a method of producing a toner having a core / shell structure by using the toner produced by the above methods as a core and attaching and fusing aggregated particles to the core.

According to one embodiment of the present invention, the toner particles are transparent particles containing no colorant. As described above, an invisible iamge may be formed when the transparent toner particles are used. When the invisible image formed by the transparent toner particles is copied with a black and white copier, the transparent invisible image is changed into a black visible image, and it can be easily determined whether the printed matter is a copy.

The invisible image may also be formed by opaque toner particles. Opaque toner particles are colored toners containing colorants. When the invisible image formed by the colored toner is copied into the color copier, the invisible image is changed into a visible image having the emission color of the phosphor in the state inherent in the colored toner image, and the color of the printed matter is changed so that the printed matter is visually copied. It can be easily judged. That is, a new color appears in which the emission color of the phosphor and the color of the colorant are mixed.

According to another embodiment of the present invention, a general two-component developing electrostatic latent image developer including the toner particles and magnetic carriers (solid carrier particles) is provided. Here, it is preferable that a magnetic carrier whose surface is covered with an insulating material is used as the magnetic carrier. More specifically, the carrier is preferably ferrite coated with an insulating material, magnetite coated with an insulating material, iron powder coated with an insulating material and mixtures thereof. In particular, ferrite or magnetite coated with an insulating material is more preferable.

According to another embodiment of the present invention, there is provided an electrophotographic image forming apparatus employing the toner particles or the electrostatic latent image developer. Here, the electrophotographic image forming apparatus means a laser printer, a copier, a facsimile or the like. Specifically, the photoconductor, a means for charging the surface of the photoconductor, a means for forming an electrostatic latent image on the surface of the photoconductor, a means for accommodating a toner or a developer, and a supply of the toner or a developer to develop an electrostatic latent image on the surface of the photoconductor to toner An electrophotographic image forming apparatus comprising means for developing an image, and means for transferring the toner image from a photosensitive member surface to a transfer material, wherein the toner or developer is a toner particle or developer according to one embodiment of the present invention. An image forming apparatus is provided.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited to these embodiments.

The terms used in the following Examples and Preparation Examples and the physical properties of the obtained resin or the physical properties of the obtained toner particles are defined or measured by the following method unless otherwise defined.

Volume average particle diameter measurement

The volume average particle diameter of the prepared toner particles was measured using a multisizer 3 (Beckman Coulter Co., Ltd., Fullerton, Calif.). In the multisizer 3, the aperture (aperture) was 100 μm, and an appropriate amount of a surfactant was added to 50-100 ml of ISOTON-II (Beckman Coulter Co., Ltd.), which is an electrolyte, and 10-15 mg of the measurement sample was added thereto. After the dispersion treatment for 1 minute in an ultrasonic disperser to prepare a sample.

Volume average particle diameter (L)

The volume average particle diameter (L) is the Powder Technology Handbook is a term defined in the pages 3 to 13 of (K. Gotoh et al., 2 nd Edition, Marcell Dekker Publications, 1997).

80% span value

The 80% span value is an index that defines the size distribution of particles.The particle size corresponds to 10% of the volume, that is, the particle size corresponding to 10% of the total volume when the volume is accumulated from small particles. , D50, the particle size corresponding to 90% was defined as d90, the values were obtained from the particle size distribution chart, and the value was calculated by the following Equation 1.

[Equation 1]

80% Span = = (d90-d10) / d50

Here, the smaller the 80% span value is, the narrower the particle distribution is, and the larger is the wider particle distribution.

Glass transition temperature (Tg, ℃) measurement

Using a differential scanning calorimeter (manufactured by Netzsch), the sample was heated to 20 ° C. to 200 ° C. at a heating rate of 10 ° C./min, quenched to 10 ° C. at a cooling rate of 20 ° C./min, and then 10 ° C. again. It measured by heating up at the heating rate of / min. The median value of each tangent line with the base line of the obtained endothermic curve was made into Tg.

Acid value measurement

The acid value (mgKOH / g) was measured by dissolving the resin in dichloromethane, cooling it, and titrating with 0.1 N KOH methyl alcohol solution.

(Synthesis of Polyester Resin)

Preparation Example 1 Synthesis of Polyester Resin (1)

A 3L reactor equipped with a stirrer, thermometer, condenser and nitrogen inlet was installed in the oil bath. 50 g of dimethyl terephthalate, 47 g of dimethyl isophthalate, 80 g of 1,2-propylene glycol and 3 g of trimellitic acid were added to the reactor. Subsequently, dibutyltin oxide was added as an polymerization catalyst in an amount of 500 ppm relative to the total weight of the monomers. The temperature was then increased to 150 ° C. while maintaining the reactor stirring speed at 150 rpm. Thereafter, the reaction was performed for about 6 hours. When methanol, a by-product of the ester reaction, was no longer obtained in the cooler, the reaction temperature was increased to 220 ° C. again, and the pressure of the reactor was reduced to 0.1torr to further react for 15 hours to complete the reaction.

After completion of the reaction, the glass transition temperature (Tg) of the polyester resin (1) was measured using a differential scanning calorimeter (DSC). As a result, the transition temperature was 65 ° C. The acid value was measured, resulting in 15 mgKOH / g. The number average molecular weight of the polyester resin (1) measured by gel permeation chromatography (GPC) using a polystyrene reference sample was 4,500, and the PDI (Polydispersity Index) was 3.5.

(Phosphor master batch manufacturing)

Preparation Example 2 Preparation of Phosphor Master Batch (1)

After mixing the polyester resin (1) synthesized in Preparation Example 1 and phosphor ZrF ₄ : Er (Nichia Chemical Co., Ltd.) at 9: 1 (90 g: 10 g) by weight, ethyl acetate was added to 100 g of the resin. The ratio was added, the temperature was raised to about 60 ° C., and the mixture was stirred with a kneader. Subsequently, the mixture was mixed at a speed of 50 rpm using a twin screw extruder connected with a vacuum apparatus, and then the ethyl acetate as a solvent was removed using the vacuum apparatus, thereby obtaining a phosphor master batch (1).

(Latex manufacturing)

Preparation Example 3 Latex Preparation

A 1 L reactor equipped with a stirrer, thermometer, condenser and nitrogen inlet was installed in the oil bath. Into the reactor, an aqueous solution in which 0.5 g of ultrapure water from which oxygen was removed was mixed with 0.5 g of anionic surfactant SDS (sodium dodecyl sulfate, Sigman-Aldrich Co. Ltd.) was added. The aqueous solution was added to the reactor and the temperature was heated to 80 ° C. When the temperature inside the reactor reached 80 ° C, an initiator solution in which 0.2 g of potassium persulfate was dissolved in 30 g of ultrapure water was added thereto, and after 10 minutes, a monomer mixture (81 g of styrene, 22 g of butyl acrylate, 2.5 g of methacrylic acid) was added. 105.5 g was added dropwise over 30 minutes and reacted for 4 hours. The heating was then stopped and naturally cooled to prepare a seed solution.

In a separate reactor, 30 g was separated from the seed solution, a mixture mixed with 351 g of ultrapure water was added thereto, and heated to 80 ° C.

Meanwhile, 43.3 g of a monomer solution consisting of 17 g of ester wax, 18 g of styrene, 7 g of butyl acrylate, and 1.3 g of methacrylic acid were dissolved in another container by heating with 0.4 g of dodecanethiol to prepare a wax / monomer mixed solution. . A pre-emulsion was prepared by adding an aqueous solution in which 1 g of SDS was dissolved in 220 g of ultrapure water into a wax / monomer mixture solution prepared in this way for about 10 minutes using an ultrasonic disperser.

The pre-emulsion was added to the separate reactor, and after about 15 minutes, an initiator solution in which 5 g of an initiator (potassium persulfate) was dissolved in 40 g of ultrapure water was added thereto. At this time, the reaction temperature was maintained at 82 ℃ to proceed the reaction for about 2 hours 30 minutes to polymerize the core (core).

After the reaction time passed, an initiator solution in which 1.5 g of an initiator (potassium persulfate) was dissolved in 60 g of ultrapure water was added thereto, and 83.5 g of a monomer solution for forming a shell layer was added thereto. The composition of the monomer introduced for shell layer formation was 56 g of styrene, 20 g of butyl acrylate, 4.5 g of methacrylic acid, and 3 g of dodecanethiol. The monomer solution was added dropwise for about 80 minutes. After the reaction for 2 hours, the reaction was terminated and naturally cooled to prepare a latex.

(Production of Phosphor Toner Particles)

Phosphor toner particles were prepared by various methods as follows.

Example 1 First Method, Polyester Resin, Phosphor M / B Use

120 g of polyester resin (1) prepared in Preparation Example 1, 80 g of phosphor master batch (1) prepared in Preparation Example 2, and 2 g of charge control agent (N-23) in a pressurized 1 L reactor equipped with a condenser, a thermometer and an impeller stirrer. 5g of HB Dinglong, Hubei, China), 5g of paraffin wax (C-8136, SER, Italy) and 300g of methyl ethyl ketone (Aldrich Chemical Company, Milwaukee, Wis.) . 50 ml of aqueous NaOH solution was added while stirring the contents at 600 rpm, and the mixture was mixed at a temperature of 80 ° C. for 5 hours at reflux. After confirming that the mixture had sufficient fluidity, the mixture was further mixed at 500 rpm for 2 hours.

Meanwhile, in a pressurized 3L reactor equipped with a condenser, thermometer, and impeller stirrer, 800 g of distilled water, 10 g of neutral surfactant (tween 20, manufactured by Aldrich Chemical Company, Milwaukee, Wisconsin), and 2 g of sodium dodecyl sulfate as an anionic surfactant ( Aldrich Chemical Company, Milwaukee, WI) was added and stirred for 1 hour at a rate of 600 rpm at a temperature of 85 ℃. Toner composition mixture prepared in the 1L reactor was added thereto and stirred at 1000 rpm for 1 hour at the same temperature to prepare an emulsion. Subsequently, while the temperature in the reactor was heated to 90 ° C., methyl ethyl ketone, which was an organic solvent, was removed at a partial pressure of 100 mm Hg. After 4 hours, the amount of methyl ethyl ketone removed was confirmed to confirm that all of the methyl ethyl ketone added was removed. The volume average particle diameter of the particles contained in the emulsion from which methyl ethyl ketone was completely removed was measured to be 0.4 μm.

Subsequently, the temperature in the reactor was cooled to 45 ° C., 10 g of magnesium chloride (MgCl ₂ ) was dissolved in 50 g of distilled water, and slowly introduced into the reactor. The temperature was raised to 80 ° C. over 30 minutes, and after 5 hours, the volume average of the particles contained in the emulsion was reached. It was 6.2 micrometers when the particle diameter was measured. Subsequently, 500 g of distilled water was added to the reactor, followed by fusion at 80 ° C. for 8 hours, and cooling. The toner particles were then separated from the emulsion using a conventional filtration device. The filter cake was washed with 1N aqueous hydrochloric acid solution and then redispersed and filtered four times in distilled water to wash and remove all surfactants contained in the filter cake. The washed toner particles were dried in a vacuum oven at 40 ° C. for 5 hours to obtain dried toner particles. The toner particle size of the prepared toner was measured using a multisizer 3 (Beckman Coulter Co., Ltd., Fullerton, Calif.), And the volume average particle size was 6.7 µm and the 80% span value was 0.55.

Toner particles containing external additives were prepared by mixing 2 parts by weight of silica (TG 810G, Cabot) and 0.5 parts by weight of silica (RX50, Degussa) for 15 minutes to 100 parts by weight of the phosphor toner particles prepared above. It was.

Example  2: first method, Vinyl  Resin, phosphor M / B not used

In a pressurized 1 L reactor equipped with a condenser, a thermometer and an impeller stirrer, 318 g of latex particles prepared in Preparation Example 3, 0.5 g of sodium dodecylsulfonate (SDS) and 500 g of ultrapure water were added thereto, and at 25 ° C., 300 rpm for 1 hour. Stirred. 18.2 g of an aqueous dispersion (solid content of 10% by weight) of a phosphor (ZrF ₄ : Er, manufactured by Nichia Chemical Co., Ltd.) was dispersed in the mixed solution. While stirring the mixture at 250 rpm, the pH of the latex phosphor aqueous dispersion was adjusted to pH 10 using 10% NaOH buffer.

A coagulant solution in which 10 g of coagulant MgCl ₂ was dissolved in 30 g of ultrapure water was added dropwise to the dispersion over 10 minutes. The reactor temperature was raised to 95 ° C. at a rate of 1 ° C./min. After 3 hours of reaction at this temperature, the reactor was naturally cooled. Then, toner particles were separated from the latex dispersion using a conventional filtration apparatus. The filter cake was washed with 1N aqueous hydrochloric acid solution and then redispersed and filtered four times in distilled water to remove all surfactants contained in the filter cake. The filtered toner particles were dried in a vacuum oven at 40 ° C. for 5 hours to obtain dried toner particles. The toner particle size of the prepared toner was measured using a multisizer 3 (Beckman Coulter Co., Ltd., Fullerton, Calif.), And the volume average particle size was 6.5 mu m and the 80% span value was 0.65.

Toner particles containing external additives were prepared by mixing 2 parts by weight of silica (TG 810G, Cabot) and 0.5 parts by weight of silica (RX50, Degussa) for 15 minutes to 100 parts by weight of the phosphor toner particles prepared above. It was.

Example  3: second method, polyester resin, phosphor M / B not used

96 g of polyester resin (weight average molecular weight: 25,000, SK chemical), phosphor ZrF ₄ : 1 g of Er (Nichia Co., Ltd.), 1 g of quaternary ammonium salt, 2 g of polyethylene wax (Toyo Petrolite Co., Ltd., polywax725) Henschel) mixer. The mixture was melt kneaded at a temperature of 165 ° C. in a biaxial melt kneader, finely ground in a jet mill grinder, and then classified in a wind classifier to prepare a toner having a volume average particle size of 8.0 μm.

A fluorescent toner was prepared by mixing 2 g of silica (TG810G: Cabot) and 0.5 g of silica (RX50, Degussa) with respect to 100 g of the toner prepared above.

Example 4 Second Method, Polyester Resin, Phosphor M / B Not Used

A phosphor toner was manufactured in the same manner as in Example 3, except that the amount of the phosphor ZrF ₄ : Er was changed from 1 g to 0.1 g.

Example 5 Second Method, Polyester Resin, Phosphor M / B Not Used

A phosphor toner was manufactured in the same manner as in Example 3, except that the amount of the phosphor ZrF ₄ : Er was changed from 1 g to 5 g.

Example 6 Second Method, Polyester Resin, Phosphor M / B Not Used

A phosphor toner was manufactured in the same manner as in Example 3, except that phosphor ZrF ₄ : Tm (Nichia Chemical Co., Ltd.) was used instead of phosphor ZrF ₄ : Er.

Example 7 Third Method, Polyester Resin, Phosphor M / B Use

400 g of distilled water, 10 g of polyvinyl alcohol (P-24; manufactured by DC Chemical Co., Seoul, Korea), 7 g of neutral surfactant (tween 20, manufactured by Aldrich Chemical Company) in a pressurized 1 L reactor equipped with a condenser, thermometer, and impeller stirrer , Milwaukee, WI), and 4.2 g of sodium dodecyl sulfate (manufactured by Junsei Chemical Company, Tokyo, Japan) as an anionic surfactant were added and stirred at a temperature of 70 ° C. at a speed of 500 rpm to completely dissolve the solids. 100 g of methyl ethyl ketone (Aldrich Chemical Company, Milwaukee, WI) was mixed with the aqueous solution to obtain a milky white microemulsion.

Next, 85 g of the polyester resin (1) synthesized in Preparation Example 1, 15 g of the phosphor master batch (1) prepared in Preparation Example 2, and 2 g of charge control agent (N-23; manufactured by HB Dinglong, China) were manufactured in Hubei. ) And carnauba wax (SX-70; max Chemical, Daejeon, Korea) were added sequentially. At this time, the polyester resin was used by grinding to a size of about 1mm.

The contents were formed while stirring the contents at 1000 rpm, then heated to reflux at 72 ° C. and stirred for 3 hours to obtain an emulsion. After stirring, it was confirmed that the resin present at the bottom of the reactor was completely dissolved to obtain a stable emulsion.

Subsequently, the stirring speed of the emulsion was reduced to 300 rpm and the temperature of the reactor was heated to 90 ° C. to remove methyl ethyl ketone, which was an organic solvent, at a partial pressure of 100 mmHg.

After 4 hours, the amount of methyl ethyl ketone removed was confirmed to confirm that all of the added methyl ethyl ketone was removed, and the emulsion was cooled to 25 ° C.

The toner particles were then separated from the emulsion using a conventional filtration device. The filter cake was redispersed and refiltered four times in distilled water to remove the surfactant and the thickener contained in the filter cake.

The refiltered toner particles were dried in a vacuum oven at 40 ° C. for one day to obtain dried toner particles.

The toner particle size of the prepared toner was measured using a multisizer 3 (Beckman Coulter Co., Ltd., Fullerton, Calif.), And the volume average particle size was 6.7 mu m and the 80% span value was 0.55.

1 part by weight of silica (TG 810G, Cabot) was mixed with 100 parts by weight of the prepared cyan toner particles in a roll mill for 15 minutes to prepare toner particles including an external additive.

Example  8: 4th method, polyester resin, phosphor M / B use

500 g of propoxylated bisphenol A polyester resin (Retichold Chemicals, Research Corp., North Carolina Research Triangle Park, Incorporated, Find Tone ^TM 82ES) in a 2000 ml volumetric flask equipped with an impeller stirrer, negative charge regulator (Orient 10 g of Bontron ^™ E-88) commercially available from Chemical Corporation, 80 g of phosphor master batch (1) prepared in Preparation Example 2, and 150 g of dimethylformamide (DMF) were mixed and then warmed to about 150 ° C. When the mixed melt had fluidity, the mixture was maintained at 50 rpm for about 1 hour. When the solution becomes clear with complete mixing, 500 g of a 1: 1 mixture of 250 g of ISOPAR-L and 250 g of ISOPAR-V (obtained from Exxon Chemical Company, Houston, Texas) and Ganex V-220 (ISP Corporation, Wayne, New) 50 g) from Jersey was mixed in a round flask. When the addition was complete, the stirring speed was raised to 400 rpm and maintained for 4 hours. When the mixture formed a milky white dispersion, the dispersion was allowed to cool to room temperature. The treated particles were separated from the reaction mixture by filtration, and the filter cake was separated by washing the solvent incorporated in the filter cake by dispersing in normal hexane. The filtered particles were dried under vacuum at 40 ° C. for 16 hours. 2 parts by weight of Cab-O-Sil TS-720 (fumed silica, which acts as a fluidity enhancer available from Cabot Corporation, Tuscala, Ill.) And 100 parts by weight of the dried particles were mixed for 15 minutes in a black Toner was obtained.

The resulting black toner contained 95.3 wt% polyester resin and 4.7 wt% carbon black, with an average particle size of 0.1 micron as measured by transmission electron microscopy. The volume average particle diameter of the toner prepared by the above invention was 4.7 microns, and the 80% span was 0.6.

Examining the toner particles with a scanning microscope revealed that the particles were all spherical and had a rough surface. The roughness index of the particles defined using the BET isothermal curve method was about 2.2.

Toner particles containing external additives were prepared by mixing 1 part by weight of silica (TG 810G, Cabot) for 15 minutes with 100 parts by weight of the prepared black toner particles.

Comparative Example 1 Second Method, Polyester Resin, Phosphor M / B Not Used

A toner was prepared in the same manner as in Example 3, except that in Example 3, except for phosphors.

Comparative Example 2: Second Method, Polyester Resin, Phosphor M / B Not Used

A phosphor toner was manufactured in the same manner as in Example 3, except that the amount of the phosphor ZrF ₄ : Er was changed from 1 g to 0.01 g.

Hereinafter, the toner particles prepared in Examples and Comparative Examples were evaluated by the following method.

(Evaluation of toner performance)

Evaluation Example 1: Quality Evaluation of Invisible Images

Using the toner particles prepared in Examples 1 to 8 and Comparative Examples 1 to 2, a 30 mm x 40 mm solid invisible image was formed on a white A4 paper in a Samsung CLP-510 printer. The quality of the invisible image was evaluated according to the following criteria. The evaluation results are shown in Table 1 below.

○: The level at which the invisible image cannot be confirmed with the naked eye.

△: level of invisible image that can be seen with the naked eye but not clearly distinguished from white paper

ㅧ: Invisible image is visible to the naked eye and is clearly distinguished from white paper.

Evaluation example  2: Quality Evaluation of Existing Visual Images

The toner particles prepared in Examples 1 to 8 and Comparative Examples 1 to 2 were partially overlapped with existing visible images on an A4 paper in which a visible image on a 30 mm x 40 mm solid was formed in a Samsung CLP-510 printer. An invisible image on a 30 mm x 40 mm solid was further formed. The quality of the visible image was evaluated according to the following criteria. The evaluation results are shown in Table 1 below.

(Circle): The level which the quality of the visible image before and after printing hardly changes.

△: A slight image quality noise is observed in the visible image after printing, but is not a problem in practical use.

×: Clear image quality noise is confirmed in the visible image after printing, which is a problem in practical use.

Evaluation example  3: evaluation of the ease of copying judgment

A4 paper on which an invisible image was additionally formed in the quality evaluation of the existing image was copied to a Document Center 286M copier of Fuji Xerox Co., Ltd. to evaluate whether the invisible image was converted into a visible image based on the following criteria. The evaluation results are shown in Table 1 below.

◎: Invisible image is turned into a visible image, and the level is represented by the image density which is not significantly different from the original visible image of the original.

(Circle): The level of an invisible image is changed to a visible image, but is displayed with a lower image density than the original visible image of the original.

(Triangle | delta): The level in which an invisible image turns into a visible image, but is blurred so that the content of an image cannot be recognized.

×: The level of difference between original and copy

TABLE 1

Used toner Quality assessment of invisible images Quality Assessment of Existing Visual Images Evaluation of Copyability Example 1 ○ ○ ◎ Example 2 ○ ○ ◎ Example 3 ○ ○ ◎ Example 4 ○ ○ ○ Example 5 △ △ ◎ Example 6 △ ○ ○ Example 7 ○ ○ ○ Example 8 ○ ○ ◎ Comparative Example 1 - ○ × Comparative Example 2 △ △ ×

As shown in Examples 1 to 8, the toner including the phosphor according to the embodiment of the present invention can easily determine whether the copy is made by changing the invisible image to a visible image before and after copying regardless of the manufacturing method. . In Comparative Examples 1 and 2, the image was not changed before and after copying, and thus it was not possible to determine whether to copy. In the case of using the toner of the present invention, it is easy to determine whether to copy or not, so that the forgery of documents and the authenticity of the toner are easy.

Claims (8)

Binder resins and anti-stokes phosphors, The anti-Stoketh phosphor is invisible to the naked eye, but is excited by infrared rays to emit invisible light, thereby forming an invisible image. The phosphor of claim 1, wherein the phosphor is YF ₃ : Yb + Er, YF ₃ : Yb + Tm, LiYF ₄ : Yb + Tm, LiYF ₄ : Yb + Er, NaYF ₄ : Yb + Tm, NaYF ₄ : Yb + Er, Toner particles, characterized in that at least one member selected from the group consisting of compounds represented by BaFCl: Yb + Er, ZrF ₄ : Er, and ZrF ₄ : Tm. The toner particles of claim 1, wherein the phosphor content is 0.05 to 10% by weight based on the total weight of the toner. The toner particles of claim 1, wherein the toner particles further comprise at least one additive selected from the group consisting of colorants, mold release agents, charge control agents and external additives. The toner particles of claim 1, wherein the toner particles are transparent. Toner particles according to any one of claims 1 to 5; And An electrostatic latent image developer comprising a carrier. An electrophotographic image forming apparatus employing the toner particles according to any one of claims 1 to 5. An electrophotographic image forming apparatus comprising the electrostatic latent image developer according to claim 6.