KR20050011397A - Non-magnetic one component negative charged toner for non-contact developer - Google Patents

Abstract

PURPOSE: A non-magnetic one component negative charged toner for a non-contact developer is provided to exhibit uniform image density over a long period and to prevent defects in image such as fogs. CONSTITUTION: The non-magnetic one component negative charged toner for a non-contact developer, comprises a binder resin, a coloring agent, a charge control agent, 0.1-4.0 wt% of an additive such as silica, titanium oxide, silicon carbide or alumina as an additive, and a resin bead having a volume average particle diameter of 5-15micrometer. Particularly, the resin bead comprises a styrene-based, a fluorine-based or an acrylic polymer having a glass transition temperature of 50-70deg.C and is added in an amount 0.1-1.0 wt%. The binder resin is preferably a styrene-based, an acryl-based, an ether-based, an ester-based or an epoxy-based copolymer or a blend thereof.

Description

Non-magnetic one component negative charged toner for non-contact developer}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for a noncontact developing device, and more particularly, to a nonmagnetic one-component auxiliary non-conductive toner for a noncontact developing device capable of preventing image contamination such as fog, which may occur in a non-image area.

Currently used printers include inkjet printers and laser printers. Because inkjet printers print slowly, they can be used as personal printers. However, in office environments, laser printers that are connected to multiple computers and networks to perform large-capacity printers are more suitable. Suitable. Such a laser printer refers to making a latent image on a photosensitive member (OPC) using a laser and then moving the toner to a latent image on the photosensitive member using a potential difference, and transferring the toner onto an image to form an image.

The laser printers currently being developed and sold are mainly black and white dry printers. This method injects charge into the toner by frictional charging and moves the toner to a latent image on the photosensitive member (OPC) by using a potential difference. There is an environmental problem due to dust or the like caused by the presence of the toner in a powder state. Since it is easy to manufacture, the manufacturing cost is low and the printer can be miniaturized.

Generally, a developer means a state in which carriers are mixed with toner, and when a carrier is not used, the toner itself may be referred to as a developer.

The dry developer can be divided into a one-component developer and a two-component developer according to the charging method of the toner particles, and can be divided into magnetic and nonmagnetic by means of moving the charged toner particles to the latent image portion. A one-component developer refers to a developer that causes charging through friction between toner particles or friction with a sleeve. A two-component developer refers to a developer that causes charging through friction with a carrier by mixing nonmagnetic toner and magnetic carrier particles. it means. While the two-component developer is relatively stable and can obtain a good recording image and is advantageous for high-speed development, the deterioration of carriers and the variation of mixing ratio of the developer and the carrier are liable to occur, and the apparatus is enlarged. Due to the miniaturization, cost reduction, and high reliability, one-component developers are frequently used. In addition, a nonmagnetic toner refers to a toner that is moved by the fluidity of the toner particles themselves without using a magnetic force. A magnetic toner refers to a toner that is moved by using a magnetic force by mixing a magnetic material such as ferrite in the toner. Since the toner does not use magnetic materials, it is inexpensive and has advantages in color printing.

Dry toner includes coloring pigments, charge control agents (CCAs) that control the amount of toner charge, binder resins that bind them, and release agents to facilitate separation of transfer objects after transfer is completed. Or an external additive for improving physical properties is formed on the surface of the toner particles.

The image forming process includes a charging step of imparting a constant electrostatic charge to a photoconductor made of a photoconductive material, an exposure step of forming a latent image on the photoconductor by a laser, and a developing step of developing a toner image by developing a developer on the latent image of the photoconductor A transfer process of transferring the toner image to a transfer material such as paper, a fixing process of fixing the toner transferred to the transfer material by heating or pressurizing, and a cleaning process of cleaning the toner and adherents remaining on the latent image carrier without being transferred Process, each of which is repeated to obtain the desired copy or printer output. 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 developed in a latent image by contact between the developing roller and the photosensitive member surface, and the non-contact type is spaced apart from the developing roller and the photosensitive member at a predetermined distance. The developer refers to a method in which the developer is moved and developed by an electric force generated according to the potential difference between the voltage applied to the developing roller and the latent potential of the photosensitive member. Among these development 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 device is durable and developed by electric force.

Such a dry developer used in a non-contact developing apparatus, the fluidity and electrical properties should not change over time and environmental conditions (eg, temperature, humidity) changes. In particular, in the conventional nonmagnetic one-component non-contact developing apparatus, the developer obtains a predetermined charging characteristic through frictional charging with the developer carrier, the developer regulating blade, and the developer supply member. However, when the printing process is repeated, the developer external additive is stressed and buried in the developer resin or falls off. When the external additive of the developer is buried or dropped into the developer resin, the fluidity of the developer decreases and the physical adsorption force between the developer carrier, the developer control blade, and the developer increases. As a result, a uniform triboelectric charge of the developer is not achieved, which lowers the predetermined triboelectric charge characteristics of the developer and results in uncharged or reverse polarity of the developer, and such uncharged or reverse polarity developer is applied to the non-image region. Develops, causing fog-like burn contamination. Therefore, in order to prevent such a problem, increasing the amount of the external additive increases the amount of frictional charge of the developer and increases the ordinary force with the developer. Therefore, the amount of movement of the toner to the photosensitive member is reduced, so that the development efficiency and image density are reduced. The problem of being lowered will occur. In addition, as the amount of the external additive is increased, the cleaning property of the cleaning blade which removes the residual developer may be deteriorated. As a result, the charge roller may be contaminated and residual developer or foreign matter may always remain on the latent image carrier, thereby causing the There is a problem that image quality is poor, such as spots, vertical white lines / black lines, and the like.

Therefore, the technical problem to be achieved by the present invention is to solve the problems of the prior art to obtain a uniform image concentration over a long life, nonmagnetic one-component for a non-contact developing device that can prevent defective images such as fog It is to provide an incidental toner.

FIG. 1 shows the fog concentration test results for the non-magnetic one-component auxiliary non-conductive toner prepared by Example 2 and Comparative Example 1. FIG.

The present invention to achieve the above technical problem,

Non-magnetic, one-component auxiliary electroconductor for non-contact developing device comprising binder resin, colorant, charge control agent, and 0.1 to 4.0% by weight of silica, titanium oxide, silicon carbide or alumina and resin beads having a volume average particle diameter of 5 to 15 탆 as external additives. Provide toner.

According to one embodiment of the invention, the resin beads may be styrene-based, fluorine-based or acrylic polymer.

Moreover, it is preferable that the addition amount of the said resin bead is 0.1-1.0 weight%.

According to another embodiment of the present invention, it is preferable that the charging sequence of the resin beads is more positive than the charging sequence of the binder resin.

According to another embodiment of the present invention, the glass transition temperature of the polymer is preferably 50 ~ 70 ℃.

The binder resin used in the toner according to the present invention may be styrene-based, acrylic-based, ether-based, ester-based, epoxy-based, blends or copolymers thereof.

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

Toner particles according to the present invention are characterized in that the binder resin, colorant, charge control agent, as an external additive comprises silica, titanium oxide, silicon carbide or alumina 0.1 to 4.0% by weight and resin beads having a volume average particle diameter of 5 to 15㎛. do.

As the binder resin, various known resins may be used, for example, polystyrene, poly-P-chlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer , Styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-propyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate Copolymer, Styrene-ethyl methacrylate copolymer, Styrene-methacrylate propyl copolymer, Styrene-butyl methacrylate copolymer, Styrene-alpha methacrylate methyl copolymer, Styrene-acrylonitrile copolymer, Styrene- Vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl ethyl ketone copolymer, styrene-butadiene balls Styrene-based copolymers such as copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic acid esters, polymethyl methacrylates, polyethyl methacrylates, polybutyl methacrylates, and copolymers thereof , Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, Aromatic petroleum resins, chlorinated paraffin, paraffin wax and the like may be used alone or in combination.

As the colorant, carbon black or aniline black may be used in the case of black and white toner, and the nonmagnetic toner according to the present invention is easy to produce color toner. In the case of the color toner, black of the colorant uses carbon black and the color further includes yellow, magenta, and cyan colorants.

As said yellow colorant, a condensed nitrogen compound, an isoindolinone compound, an atlakin compound, an azo metal complex, or an allyl imide compound is used. Specifically C.I. Pigment Yellow 12, 13, 14, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168 or the like can be used.

As the magenta colorant, a condensed nitrogen compound, anthrakin, quinacridone compound, a base dye late compound, a naphthol compound, a benzo imidazole compound, a thioindigo compound, or a perylene compound is used. Specifically C.I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, or 254 may be used.

As the cyan colorant, a copper phthalocyanine compound and a derivative thereof, an anthrakin compound, a basic dye rate compound and the like are used. Specifically C.I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 or the like can be used.

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.

The content of the colorant may be any amount sufficient to color the toner capable of forming a visible image by development, but is preferably 2 to 20 parts by weight based on 100 parts by weight of the binder resin. If it is less than 2 parts by weight, the coloring effect is insufficient, and if it exceeds 20 parts by weight, the electrical resistance of the toner is lowered, so that a sufficient frictional charge amount cannot be obtained, resulting in problems such as contamination.

As the charge control agent used in the present invention, as an auxiliary charge control agent, for example, oil-soluble azo dyes, salicylic acid metal complexes, nigrosine dyes, quaternary ammonium salts, triphenylmethane-based control agents, oil-soluble dyes such as oil black, naphthenic acid, Salicylic acid, octylic acid and their manganese, cobalt, iron, zinc, aluminum, lead and other metal salts, alkyl salicylic acid metal chelate and the like, and the like is not particularly limited.

On the other hand, the toner particles according to the present invention may further include a release agent, a higher fatty acid or a metal salt thereof, such as low molecular weight polypropylene, polyalkylene wax such as low molecular polyethylene, paraffin wax, higher fatty acid, fatty acid amide, etc. The higher fatty acid or the metal salt thereof may be used to protect the photoconductor and prevent deterioration of development characteristics to obtain a high quality image.

Silica, titanium oxide, silicon carbide, or alumina used as an external additive in the present invention is used to improve the fluidity of the toner, and is generally 10 to 100 nm in size, and the content is preferably 0.1 to 4.0% by weight. If it is less than 0.1% by weight, the fluidity improving effect is insignificant, and if it exceeds 4% by weight, the toner's physical properties may deteriorate, such as deterioration of the toner's fixability.

The resin beads used in the present invention preferably have a volume average particle diameter of 5 to 15 µm, and may be polystyrene, fluorine or acrylic polymer.

Examples of the styrene-based polymer include polystyrene, poly-P-chlorostyrene, poly-α-methylstyrene, and the like, and fluorine-based polymers include polytetrafluoroethylene, polytrifluorochloroethylene, polyvinylidene fluoride, and the like. Examples of the acrylic polymer include, but are not limited to, polymethyl (meth) acrylate, polyethyl (meth) acrylate, polybutyl (meth) acrylate, and the like.

The resin beads used in the present invention are characterized in that the charging sequence is more positive than the charging sequence of the binder resin, and serves as a carrier for making the toner itself negatively charged by friction with the binder resin. That is, when using polyester as the binder resin, resin beads having a higher charge sequence should be used, for example, polystyrene may be used. On the other hand, the weight average molecular weight of the polymer used in the resin beads is not particularly limited, but is preferably 10,000 to 100,000, when the weight average molecular weight is less than 10,000, there is a risk of causing a phase change when left for a long time, when exceeding 100,000 It is not preferable because it may adversely affect the fixability.

The resin beads according to the present invention is characterized in that the volume average particle diameter is 5 ~ 15㎛, when the volume average particle diameter is less than 5㎛ there is a problem that the cleaning property is poor, when exceeding 15㎛ It is unfavorable because it becomes weak and there exists a problem that supplyability of a developer falls and fog concentration becomes high.

On the other hand, the addition amount of the resin beads is preferably 0.1 to 1.0% by weight, more preferably 0.3 to 0.6% by weight, but less than 0.1% by weight of the addition effect is weak and exceeds 1.0% by weight of the developer supply It is not preferable because it may cause deterioration.

According to another embodiment of the present invention, it is preferable that the glass transition temperature of the polymer is 50 ~ 70 ℃, when the glass transition temperature is less than 50 ℃ cake phenomenon or blocking (blocking) the developer hardens at high temperature ), Which is not preferable because there is a risk of phenomenon, and there is a problem that fixability is lowered when it exceeds 70 ° C.

In the non-contact developing method using a non-magnetic one-component developer, as the printing increases, the stress of the developer increases, so that the smaller particle average diameter among additives such as silica and titanium oxide is relatively buried in the developer resin and the particle average diameter The larger one is separated from the developer matrix. Since the resin beads used in the present invention have a relatively large particle size among the additives, the resin beads are stressed as the number of prints increases, thereby leaving the developer matrix. Since the resin beads thus separated are more positive than silica or titanium oxide in the triboelectric charge sequence, they tend to adhere to the feed rollers applied relatively negatively than the developing roller. Therefore, as the number of prints increases, the amount of resin beads remaining undeveloped increases in the developing chamber, which determines that the triboelectric charge characteristics of the developer are uniform by performing a kind of carrier role having reverse polarity with respect to the developer. do. That is, the resin bead may be considered to play a role of a carrier having a kind of reverse polarity, thereby suppressing the occurrence of the reverse polarity developer or the uncharged developer and thereby reducing the fog concentration in the non-image region.

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 agitated to attach the external additive to 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 part of the external additive particles to the surface of the toner particles. You may bury it and fix it.

Hereinafter, a preferred embodiment of the present invention will be described in more detail, but the present invention is not limited thereto.

Example 1

100 parts by weight of polystyrene having a weight average molecular weight of 30,000, 5 parts by weight of carbon black (manufactured by Degu Co., Ltd.), and 2 parts by weight of a charge control agent (Orient Chemical Company, Bontron S-54) using a Henschel type mixer I was. Next, the mixture was introduced into a twin screw extruder, the melt mixture was extruded at 130 ° C., cooled and solidified, pulverized by a jet mill grinder, and then classified by a wind classifier toner having an average particle size of about 8 μm. The particles were obtained. Next, 0.4 wt% of silica particles having a volume average particle diameter of 10 nm, 1.0 wt% of silica particles having a volume average particle diameter of 40 nm, and 0.5 wt% of titanium oxide having a volume average particle diameter of 10 nm were added to the toner particles as an additive for improving fluidity. Then, 0.1 part by weight of polystyrene having a weight average molecular weight of 10,000 and a volume average particle diameter of 5 μm was dispersed and mixed using 100 parts by weight of the toner and a blender to prepare a nonmagnetic one-component toner.

Example 2

A nonmagnetic one-component toner was prepared in the same manner as in Example 1, except that 0.1 part by weight of polystyrene having a weight average molecular weight of 10,000 and a volume average particle diameter of 10 μm was used.

Example 3

A nonmagnetic one-component toner was prepared in the same manner as in Example 1, except that 0.1 part by weight of polystyrene having a weight average molecular weight of 20,000 and a volume average particle diameter of 15 μm was used.

Example 4

A nonmagnetic one-component toner was prepared in the same manner as in Example 1, except that 0.1 part by weight of polyvinylidene fluoride having a weight average molecular weight of 15,000 and a volume average particle diameter of 10 μm was used.

Example 5

A nonmagnetic one-component toner was prepared in the same manner as in Example 1, except that 0.1 part by weight of polymethyl methacrylate having a weight average molecular weight of 30,000 and a volume average particle diameter of 10 μm was used.

Example 6

A nonmagnetic one-component toner was prepared in the same manner as in Example 1 except that 0.5 weight part of polystyrene having a weight average molecular weight of 10,000 and a volume average particle diameter of 10 μm was used.

Example 7

A nonmagnetic one-component toner was prepared in the same manner as in Example 1 except that 1 part by weight of polystyrene having a weight average molecular weight of 10,000 and a volume average particle diameter of 10 μm was used.

Comparative Example 1

A nonmagnetic one-component toner was prepared in the same manner as in Example 1 except that no resin beads were added.

Comparative Example 2

A nonmagnetic one-component toner was prepared in the same manner as in Example 1, except that 0.1 part by weight of polystyrene having a weight average molecular weight of 10,000 and a volume average particle diameter of 2 μm was used.

Comparative Example 3

A nonmagnetic one-component toner was prepared in the same manner as in Example 1, except that 0.1 part by weight of polystyrene having a weight average molecular weight of 30,000 and a volume average particle diameter of 20 μm was used.

Test Example 1

Fog concentration test

Using the nonmagnetic one-component toner prepared in Example 2 and Comparative Example 1, the process speed was 124 mm / sec, set in an A4 standard 21 ppm laser printer (manufactured by Samsung Electronics), and the fog concentration was measured. Fog taping concentration was measured using a Mcbeth densitometer RD918 and the tape used for fog taping was 810D from 3M. In the fog taping for the non-image area, the concentration was measured by stopping the printer in the middle of white paper printing and then taping the area before transfer on the latent image carrier, and the result is shown in FIG. 1. The basic concentration of the fog is 0.11, the concentration is 0.13 or less is excellent, when 0.14 to 0.15 is usable level, when 0.16 or more is poor level. As can be seen in FIG. 1, the concentration of fog was almost similar to 2000 sheets when the nonmagnetic one-component toner prepared in Example 2 and Comparative Example 1 were used, but after 4000 sheets, the toner of Example 2 was printed. As the number of sheets increases, the fog concentration is lower than that of the initial stage, whereas in Comparative Example 1, the fog concentration increases in proportion to the number of printed sheets. That is, it can be seen that the toner according to the present invention provides good image quality in which fog does not occur in the non-image area as the number of prints increases.

Test Example 2

Relationship test between the volume average particle diameter of beads and burn contamination

As in Test Example 1, the process speed is 124mm / sec and A4 standard 21ppm laser printer continuously prints up to 8,000 sheets in 5% Character pattern at room temperature and humidity environment. Examining whether or not contamination occurred, the results are shown in Table 1 below.

As can be seen in Table 1 below, the toner according to the exemplary embodiment of the present invention had good cleaning properties, and image contamination did not occur up to 8,000 sheets, but in the case of Comparative Example 1 without using resin beads, 6,000 was used. Image contamination occurred at every sheet, and even in Comparative Example 2 having a volume average particle diameter of 2 µm, image contamination occurred after printing 8,000 sheets due to the deterioration of cleaning property. In addition, in the case of Comparative Example 3 having a volume average particle diameter of 20 μm, the level was usable even when printing 8,000 sheets, but there was a problem in that the halftone was rough.

Early 2,000 sheets 4,000 sheets 6,000 sheets 8,000 sheets Example 1 ○ ○ ○ ○ ○ Example 2 ○ ○ ○ ○ ○ Example 3 ○ ○ ○ ○ ○ Example 4 ○ ○ ○ ○ ○ Example 5 ○ ○ ○ ○ ○ Example 6 ○ ○ ○ ○ ○ Example 7 ○ ○ ○ ○ ○ Comparative Example 1 ○ ○ △ X X Comparative Example 2 ○ ○ ○ △ X Comparative Example 3 ○ ○ ○ ○ △

○: Good, △: Usable level, ×: Poor (image contamination)

As described above, when the non-magnetic one-component toner for a non-contact developing device according to the present invention is used, even if there is no separate operation such as improving the pressure of the cleaning blade or the surface lubricity of the latent image bearing member, it is possible to use it for a long period of time. Uniform image density can be obtained, and defective images such as fog can be prevented.

Claims (6)

Non-magnetic, one-component auxiliary electroconductor for non-contact developing device comprising binder resin, colorant, charge control agent, and 0.1 to 4.0% by weight of silica, titanium oxide, silicon carbide or alumina and resin beads having a volume average particle diameter of 5 to 15 탆 as external additives. toner. 2. The nonmagnetic one-component auxiliary electrostatic toner for a non-contact developing apparatus according to claim 1, wherein the resin beads are styrene-based, fluorine-based, or acrylic polymers. 2. The nonmagnetic one-component auxiliary electrostatic toner for a noncontact developing apparatus according to claim 1, wherein the amount of the resin beads added is 0.1 to 1.0 wt%. 2. The nonmagnetic one-component auxiliary electrostatic toner for a non-contact developing apparatus according to claim 1, wherein the charging sequence of the resin beads is more positive than the charging sequence of the binder resin. 2. The nonmagnetic one-component auxiliary electrostatic toner for a noncontact developing apparatus according to claim 1, wherein the glass transition temperature of the polymer used in said resin beads is 50 to 70 占 폚. 2. The nonmagnetic one-component incidentally conductive toner for a non-contact developing apparatus according to claim 1, wherein the binder resin is styrene, acrylic, ether, ester, epoxy, blends or copolymers thereof.