KR100636134B1 - Toners for electrophotographic imaging apparatuses having uniform charge distribution and improved anti-offset property - Google Patents

Abstract

A toner for an electrophotographic image forming apparatus comprising a binder resin, a colorant, a mold release agent, and a charge control agent, wherein the toner includes inorganic fine particles made of a mixture of magnetite fine particles and silica fine particles as internal additives, and the toner is used as an external additive. A toner for an electrophotographic image forming apparatus comprising an organic charge control agent is disclosed. The toner according to the present invention can maintain the toner charge amount and the charge distribution uniformly, improve the supplyability and the background, and improve the anti-offset property through good dispersion of the releasing agent, thereby achieving high quality images. Can be obtained.

Toner for electrophotographic image forming apparatus, low melting point release agent, inorganic fine particles, organic charge control agent

Description

Toners for electrophotographic imaging apparatuses having uniform charge distribution and improved anti-offset property

1 illustrates an example of a conventional non-contact developing electrophotographic image forming apparatus.

<Description of Drawing>

1: photosensitive member

2: developing roller

3: toner feed roller

4: toner

5: toner layer regulating device

6: charging device

7: cleaning blade

8: residual toner

9: Laser Scanning Unit (LSU)

The present invention relates to a toner for an electrophotographic image forming apparatus, and more particularly, toner charge amount and charge distribution can be kept uniform, supplyability and background can be improved, and an inoffset ( The present invention relates to a toner for an electrophotographic image forming apparatus which can obtain a high quality image by improving anti-offset property.

Fig. 1 schematically shows an example of a conventional non-contact developing electrophotographic image forming apparatus, and the operation thereof is as described below. That is, after the photosensitive member 1 is charged by the charging device 6, an electrostatic latent image is formed on the photosensitive member by image exposure through a laser scanning unit (LSU) 9. The toner 4 is supplied to the developing roller 2 by the toner supply roller 3. The toner supplied to the developing roller 2 is thinned to a uniform thickness by the toner layer regulating device 5, and charged with high friction. The toner that has passed through the toner layer restricting device 5 is developed by electrostatic force on the electrostatic latent image formed on the photoconductor 1, and the developed toner is transferred to the paper by a transfer roller (not shown), and then fixed by a fuser (not shown). Settles down. The residual toner 8 after transfer on the photoconductor is also cleaned by the cleaning blade 7.

In the image forming method in which charging → exposure → development → transfer → cleaning → charging (repeating afterward) as described above, the image formation is performed using the toner layer regulating device (M / A) of the toner conveyed to the developing area (mg / cm). ² : Toner weight per unit area measured on the developing roller after passing through the toner layer regulating device) and Q / M (μC / g: per unit weight measured on the developing roller after passing through the toner layer controlling device) After adjusting the amount of toner charging), and by the electric field acting between the developing roller and the photosensitive member. The developing process of the process is divided into a contact type and a non-contact type, wherein the contact type refers to a method in which the developer is transferred to the latent image by contacting the surface of the developing roller and the photoconductor. The developer refers to a method in which the latent image is transferred and developed by an electric force generated according to a potential difference between the voltage applied to the developing roller and the latent potential of the photosensitive member. Among these developing methods, the contact type has a problem of wear of the photosensitive member and the developing roller, while the non-contact type has the advantage of excellent resolution because the durability of the device is excellent and developed by electric force.

In general, in the electrophotographic image processing apparatus as described above, the developer means a state in which a carrier is mixed with the toner, and when the carrier is not used, the toner itself may be referred to as a developer. A nonmagnetic developer is a developer that moves by the fluidity of the developer particle itself without using a magnetic force. A magnetic developer is a phenomenon in which a magnetic material is moved by mixing magnetic materials such as ferrite in the developer. Says 1st.

Background Art Recently, as an electrophotographic image forming apparatus such as an electrophotographic color copying machine is widely used, high quality image quality is required. In addition, low-temperature fixing characteristics of the toner are required for lowering energy, reducing printing waiting time, and the like, and a binder resin and a release agent (Wax) having excellent fixing characteristics in a long range are used for this purpose. In addition, in order to improve developability, durability, transfer efficiency, and to prevent fogging of non-image portions, toner particles are spherical, and fluidity and charging characteristics of toner particles are improved through external addition of silica and TiO ₂ .

However, in the one-component developer, the charge control agent may cause problems such as low triboelectric chargeability, poor dispersion, low storage stability, and the like, and the release agent added as an offset inhibitor increases dispersibility as the amount added increases. Deterioration, adhesion to the photoconductor, resulting in deterioration of adhesion of the external additives in the toner, resulting in contamination of the photoconductor and the charging device.

Among various developing methods using one-component developer, non-contact one-component developing method can be miniaturized, easy to cope with color, excellent edge reproducibility and tone gradation, and high resolution printing quality. It is possible. However, in the case of the non-contact one-component developing method, it is necessary to maintain a constant charge amount and a uniform charge distribution of the toner not only in the early stages but also after long-term operation in order to maintain stable developability and prevent fog and scattering.

In order to solve the above problems and to provide uniform chargeability to the toner, a method of forming a thin toner layer on the developing roller is also possible, but if the toner layer is made too thin, the toner deteriorates due to toner stress, Streaks are easily generated by fusion to the restricting device, and the development efficiency is drastically lowered due to a sharp increase in the toner charging amount, and thus a decrease in image density is likely to occur. On the other hand, when the toner charging amount is adjusted downward to improve the development efficiency drop, problems such as increased fog and contamination by toner scattering occur. In addition, toner charge may be controlled by adding an external additive such as silica or TiO ₂ to maintain the charge stability and uniform charge distribution of the toner during long term operation. There is a limit to gender improvement.

The technical problem to be achieved by the present invention is to solve the problems according to the prior art, to maintain a stable toner charge amount and charge distribution, to improve the supplyability and background, and through the good dispersion of the release agent anti-offset (anti It is to provide a toner for an electrophotographic image forming apparatus which can obtain a high quality image by improving the -offset property.

Another object of the present invention is to provide an electrophotographic image forming apparatus employing the toner.

The present invention to achieve the above technical problem,

A toner for an electrophotographic image forming apparatus comprising a binder resin, a colorant, a mold release agent, and a charge control agent, wherein the toner includes inorganic fine particles made of a mixture of magnetite fine particles and silica fine particles as internal additives, and the toner is used as an external additive. Provided is a toner for an electrophotographic image forming apparatus, comprising an organic charge control agent.

The present invention to achieve the above other technical problem,

An electrophotographic image forming apparatus employing the toner is provided.

The toner for an electrophotographic image forming apparatus according to the present invention can stably maintain a toner charge amount and a charge distribution, improve supplyability and background, and improve anti-offset property through good dispersion of a release agent. As a result, a high quality image can be obtained.

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

The present invention relates to a toner used in an electrophotographic image forming apparatus such as a laser printer, a facsimile machine, a copier, etc., comprising inorganic fine particles composed of a mixture of magnetite fine particles and silica fine particles as an internal additive, and containing an organic charge control agent as an external additive. A toner for an electrophotographic image forming apparatus is provided.

As the binder resin that can be used in the toner according to the present invention, conventional binder resins used in the manufacture of toners for electrophotographic image forming apparatuses can be used, but are not limited thereto, polystyrene-co-butadiene, polystyrene -Co-acrylonitrile, modified acrylic polymer, polyvinyl acetate, styrene-alkyd resins, soya-alkyl resins, polyvinylchloride, polyvinylidene chloride, polyacrylonitrile, polycarbonates, polyacrylic acid, poly Acrylates, polymethacrylates, styrene polymers, polyvinyl butyral, alkyd resins, polyamides, polyurethanes, polyesters, polysulfones, polyethers, polyketones, phenoxy resins , Epoxy resins, silicone resins, polysiloxanes, poly (hydroxyether) resins, polyhydroxystyrene Resins, novolacs, poly (phenylglycidylether) -co-dicyclopentadiene, copolymers of monomers used in the above-mentioned polymers, and combinations thereof, among others polyester resins Is excellent in fixability and transparency and is suitable for color developers.

In addition, as the colorant which may be used in the toner according to the present invention, conventional colorants used in the manufacture of toners for electrophotographic image forming apparatuses in the art may be used, but are not limited thereto. Or aniline black, for example, in the case of a color toner, the color of the colorant uses carbon black and the color further includes yellow, magenta, and cyan colorants. Such colorants may be used alone or in admixture of two or more thereof, and are selected in consideration of color, saturation, lightness, weather resistance, dispersibility in toner, and the like.

In addition, as a charge control agent that may be embedded in the toner according to the present invention, a conventional charge control agent used in the manufacture of toner for an electrophotographic image forming apparatus may be used, but is not limited thereto. Organometallic complexes or chelate compounds such as chromium containing azo dyes or monoazo metal complexes as yesterday; Metal containing salicylic acid compounds such as chromium, iron, aluminum and zinc; And organometallic complexes of aromatic hydroxycarboxylic acids with aromatic dicarboxylic acids may be used, and products modified with nigrosine and fatty acid metal salts thereof as (+) charge control agents; Triphenylmethane derivatives; And tributylbenzylammonium 1-hydroxy-4-naphthosulfonate, tetrabutyl ammonium tetrafluoroborate, stearyldimethylbenzylammonium paratoluenesulfonate, stearyldimethylbenzylammonium methyl sulfate, stearyldimethylphenethylammonium methyl Onium salts including quaternary ammonium salts such as sulfate, distearyldimethylammonium chloride, decyltrimethylammonium hydroxide, and the like can be used alone or in combination of two or more thereof.

The toner according to the present invention includes a release agent, but is not limited to polyalkylene wax such as low molecular weight polypropylene, low molecular polyethylene, ester wax, carnauba wax, paraffin wax, higher fatty acid, fatty acid amide. And the like, and specifically, fluorinated polymer, siloxane polymer, fluorosilicone polymer, polysilane, polyethylene, polypropylene, polyacrylate, poly (methyl methacrylate-co-methacrylic acid), urethane water Feeders, urethane-epoxy resins, acrylated-urethane resins, urethane-acrylic resins, or combinations thereof can be used as the release agent.

Preferably, the release agent is a low melting point release agent having a melting point of 70 ° C. to 120 ° C., and the reason why such a low melting point release agent is preferable in the manufacture of the toner according to the present invention may be offset by using a low melting point release agent. Because. If the melting point range of the low-melting release agent is less than 70 ℃, the adhesiveness is high, the agglomeration of the toner particles occurs, the storage stability is low, and when it exceeds 120 ℃, the release effect by the release agent in low temperature fixing There is a problem that can not be obtained sufficiently.

The toner according to the present invention contains inorganic fine particles composed of a mixture of magnetite fine particles and silica fine particles as internal additives. The inorganic fine particles are embedded in the toner to improve anti-offset resistance through good dispersion of the release agent, and effects such as fluidity, transferability and durability improvement can be obtained through the addition of such inorganic fine particle additives. .

In the prior art, by adding these inorganic fine particles to the toner, there is a possibility that the inorganic fine particles adhere to the air holes present in the external appearance of the non-added toner and can be released over time. It is protruded to the outside of the toner by being incorporated into the toner, and therefore, there is less possibility of detachment even under prolonged operation, so that the effect of the inorganic fine particles can be maintained.

The content of the magnetite fine particles is 0.7 to 12.0 wt% based on the total weight of the toner, and the content of the silica fine particles is 0.1 to 5.0 wt%. If the content of the inorganic fine particles is less than the above range is not preferable because the effect by the addition of the inorganic fine particles can not be obtained, and if it exceeds the above range there are problems such as poor fixability, overcharge and poor cleaning, etc. not.

It is preferable that the average particle diameter of the magnetite fine particles is 0.05 to 1.0 micron, and the average particle diameter of the silica fine particles is 5 to 20 nm. If the average particle diameter of the inorganic fine particles is less than the above range, it is not preferable because a small amount of fine particles may be buried in the toner.

On the other hand, the toner according to the present invention contains an organic charge control agent as an external additive. The organic material charge control agent attached to the toner particles can maintain the charge amount and the charge distribution more uniformly by externally adding the organic material charge control agent separately from the normal charge control agent embedded as described above.

The organic material charge control agent added as the external additive preferably has a Tg value of 50 to 70 ° C, a melt index of 5 to 10 g / 10 minutes, and an acid value of 1 to 30 mgKOH / g.

Preferably, the toner according to the present invention further includes, as an external additive, first and second silica fine particles and titanium oxide fine particles having different particle diameters, respectively.

The first silica fine particles added as an external additive have a relatively large primary particle size in the range of 30 to 200 nm, and the second silica has a small primary particle size in the range of 5 to 20 nm. The primary role of the first silica particles in the use of silica particles having different particle diameters as spacer particles is to prevent toner deterioration due to durability and to improve transferability, and the second silica mainly imparts fluidity to the toner. It plays a role. The amount of the first and second silica particles is preferably 0.1 to 3.5% by weight and 0.1 to 4.0% by weight based on the total weight of the toner, respectively.

In addition, the titanium oxide fine particles added as an external additive have a primary particle size of 10 to 200 nm, and the content thereof is preferably 0.1 to 3.0% by weight based on the total weight of the toner.

The toner according to the present invention may be prepared by a melt kneading pulverization method as well as a polymerization method. In order to attach the external additives to the toner particles, the toner particles and the external additives are blended in a predetermined ratio, and stirred in a Henschel mixer or the like. It is loaded into the apparatus and stirred to attach the external additive on the surface of the toner particles, or both particles are loaded and stirred by a surface reformer such as a 'nara hybridizer' and at least a portion of the external additive particles on the surface of the toner particles. You may bury it and fix it.

The present invention also provides an electrophotographic image forming apparatus employing the toner. The electrophotographic image forming apparatus in which the toner according to the present invention may be employed includes a conventional electrophotographic image forming apparatus such as a laser printer, a facsimile, a copier, and the like, and specifically, a laser beam or an LED print head type printer, a facsimile, Examples thereof include copiers and multifunction machines.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example. Preparation of Toner According to the Present Invention (Unchargeable Toner Standard)

A toner having the following composition was prepared.

100 wt% polyester

5% by weight carbon black

3% by weight of additive antistatic agent (Hodogaya, T-77)

Carnauba Wax 2% by weight

2% by weight of magnetite particles

2% by weight of silica particles

The composition was uniformly premixed using a Henschel type mixer, then fed into a twin screw extruder to extrude the melt mixture at 120 ° C., cooled and solidified. Thereafter, untreated toner particles having an average particle diameter of about 8 μm were obtained using a pulverizer, and then the following external additives were subjected to external treatment to prepare a toner according to the present invention.

Secondary Silica (I) (Primary particle size 30 ~ 200 nm) 1.0 wt%

Secondary Silica (II) (Primary Particle Size 5 ~ 20 nm) 1.5 wt%

Titanium oxide fine particles (primary particle size 10 ~ 200 nm) 1.0 wt%

Styrene Acrylic Charge Control Agent 1.0 wt%

Comparative example. Preparation of toner according to the prior art (based on antistatic toner)

The toner was manufactured in the same manner as in the above-described manufacturing method, except that magnetite fine particles and silica fine particles among the internal components were not included and organic fine particles among the external components were included.

<Image evaluation test>

The development experiment was conducted under the following development conditions.

Surface potential (V _O ): -700 V

Latent _Image Potential (V _L ): -100 V

Developer roller applied voltage: V _pp = 1.8 kV, frequency = 2.0 kHz

V _dc = -500 V, duty ratio = 35% (square wave)

Development gap (GAP): 150 to 400 μm

Developing Roller: 1) For Aluminum

Roughness (R _z ) = 1 to 2.5 (after nickel plating)

           2) In case of rubber roller (NBR-based elastic rubber roller)

Resistance = 1 × 10 ⁵ to 5 × 10 ⁶ Ω

           Longitude = 50 °

Toner: Charge amount (q / m) = -5 to -30 μC / g (on developing roller after passing toner layer regulator)

Toner level per area = 0.3 to 1.0 mg / cm ²

Under the same conditions as above, images were evaluated using a 20 ppm LBP printer for the toners of Examples and Comparative Examples. For each image, each image was evaluated by observing changes in image density, fog (contamination of the background and non-image areas), dot reproducibility, and supplyability with increasing number of prints.

Image density was measured by using a densitometer (SpectroEye, Gretag Macbeth) of the density of the solid pattern on the paper. When the image density is less than 1.1, it is expressed as X, when it is 1.1 to 1.3, and when it is 1.3 or more, it is expressed as O.

The fog was measured using a densitometer (SpectroEye, GretagMacbeth) in the non-image area on the photosensitive medium. In the case of a fog of 0.14 or less, it is indicated by O, in the case of 0.15 to 0.16, by △, and in the case of 0.17 or more by X.

Dot reproducibility was visually evaluated. Dot reproducibility is indicated by O when no problem occurrence is recognized by visual judgment, and X when a problem occurrence is recognized by visual judgment.

The feedability was visually evaluated for the printed image, marked as O for an even image, Δ for a less uniform image, and X for an uneven image. In this case, the image refers to a black chart.

Image evaluation results of the toners according to the examples and the comparative examples are shown in Tables 1 and 2 below.

Image evaluation result of the toner according to the embodiment  Item The number of prints Early 1,000 2,000 3,000 4,000 5,000 Burn density O O O O O O Fog O O O O O △ Dot reproducibility O O O O △ △ Supplyability O O O O △ △

Image evaluation result of toner according to a comparative example  Item The number of prints Early 1,000 2,000 3,000 4,000 5,000 Burn density O O O O O O Fog O O O △ △ △ Dot reproducibility O O O O △ △ Supplyability O O O △ △ X

As can be seen from the image evaluation results of Table 1 and Table 2, the toner according to the present invention maintained a certain level or more of image concentration even after printing for a long time, and also the toner according to the prior art in suppressing fog generation, dot reproducibility and supplyability. The results were excellent compared to the above.

According to the present invention, it is possible to stably maintain the charge amount and charge distribution of the toner, improve the supplyability and the background, and improve the anti-offset property through good dispersion of the release agent, thereby obtaining a high quality image. A toner for an electrophotographic image forming apparatus can be provided.

Claims (5)

A toner for an electrophotographic image forming apparatus comprising a binder resin, a colorant, a mold release agent, and a charge control agent, wherein the toner is an internal additive having an average particle diameter of 0.05 to 1.0 micron of magnetite fine particles of 0.7 to 12.0 wt% and an average particle diameter of 5 to 20 nm. A toner for an electrophotographic image forming apparatus, comprising inorganic fine particles composed of a mixture of 0.1 to 5.0 wt% of silica fine particles, and wherein the toner contains an organic charge controlling agent as an external additive. The toner for electrophotographic image forming apparatus according to claim 1, wherein the release agent is a low melting point release agent having a melting point of 70 ° C to 120 ° C. delete An electrophotographic image according to claim 1, wherein the organic charge control agent added as the external additive has a Tg value of 50 to 70 ° C, a melt index of 5 to 10 g / 10 minutes, and an acid value of 1 to 30 mgKOH / g. Toner for forming apparatus. An electrophotographic image forming apparatus employing the toner according to any one of claims 1, 2, and 4.

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