JPH09288383A - Electrostatic developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing method which does not cause splashing of a toner, fog on a white base, void or ghost and realizes a long life and high image quality. SOLUTION: By this method, a developer layer regulating member is pressed to a developer carrying body and the carrying body is relatively moved to the regulating member to pass a one-component electrostatic developer essentially comprising toner particles in the pressed part. In the process of passing the developer, a developer layer is formed on the carrying body and the developer on the carrying body is transferred to an electrostatic latent image holding member in a facing zone with the electrostatic latent image holding member to visualize the image. In this method, one of the surfaces of the developer carrying body and the layer regulating member in contact with the toner particles is made of an inorg. material. The toner particles contain a boron- contg. org. material expressed by the formula. In the formula, R1 , R4 are independently hydrogen atoms, alkyl groups, substd. or unsubstd. aromatic rings (including condensed rings), R2 , R3 are independently substd. or unsubstd. aromatic rings (condensed rings), and X<+> is a cation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry electrostatic image developing method and 1 used in electrophotography, electrostatic recording and the like.
The present invention relates to a component electrostatic developer.

[0002]

2. Description of the Related Art Generally, in the electrophotographic system, an electrostatic latent electric image is formed by various means on a photoconductor (usually a photosensitive drum processed into a drum shape) containing various photoconductive substances, and the electrostatic latent image is formed. The electrostatic latent image is developed with a developer made of powder, and if necessary, the powder is transferred onto a substrate such as paper or film, and then fixed by a method such as pressing or heating. As the developer, a two-component developer composed of a carrier such as iron powder or ferrite powder and a toner and a one-component developer (non-magnetic or magnetic toner) not requiring a carrier are known.

As a developing method using a one-component developer,
A developer layer is adhered and formed on the surface of a developer carrier, and the developer is transferred by contacting it with an electrostatic latent image holding member such as a photoconductor, or by transferring the developer in a non-contact manner. Flying development methods are known. The electrostatic force control method for transferring the developer may be a method of forming a DC electric field between the developer carrying member and the latent image holding member or a direction toward the latent image holding member by applying an AC bias to the carrying member. A method is known in which an electric field is applied alternately to the direction of travel.

As a method of forming a developer layer on the developer carrying member, the developer carrying member is opposed to the developer layer thickness regulating member and is relatively moved to regulate the amount of the developer when passing through the opposed area. However, a method of forming a developer layer on the carrier is common. In the two-component developing method using magnetic carrier particles and the developing method using magnetic toner, the developer is magnetically attracted to a carrier (magnet roller) having a magnetic field generating means on the back surface of the carrier to regulate the carrier. A general method is to form a developer layer by passing the member through a gap keeping an appropriate distance.

When a non-magnetic developer such as a non-magnetic one component is used or a magnetic restraining force is not used, it is necessary to form the developer layer by Coulomb force due to frictional charge. In these cases, a sufficient amount of electrostatic charge cannot be secured just by passing through the gap as in the above, and the developer layer thickness may become non-uniform or the developer may be scattered to the periphery.
Therefore, in the case of a method that does not use magnetic force, the developer layer thickness regulating member is generally pressed against the developer carrier. That is, the developer is carried by the carrier, and by passing while pressing the pressing portions of the regulating member and the carrier,
A stable developer layer can be formed by forming a proper developer layer thickness and at the same time obtaining a sufficient frictional charge by the friction energy when the pressing portion is expanded.

The toner is a black toner containing a black dye or pigment such as carbon black, a monocolor toner used for monochromatic development or the like, and a full color development using cyan, magenta and yellow toners (black toner if necessary) in combination. Toner can be roughly classified. In the case of mono-color toners and full-color toners, there are restrictions on the materials that can be contained in the developer in order to obtain the desired hue. Generally, in order to improve the triboelectric chargeability of the toner, a charge control agent is contained in the toner. The charge control agent used for the color toner is generally colorless or white or a very pale color.

In the case of full-color toner, the image is required to have glossiness. In addition, transparency is required because it is also used for an overhead projector film and the like. A binder resin having a narrow molecular weight distribution is generally used to reproduce gloss and transparency. On the other hand, as a method for producing a toner, a pulverized toner production method for obtaining a toner particle having a desired particle diameter by pulverizing a toner raw material obtained by mixing and kneading a binder resin and other components, cooling and solidifying, and a necessary component There is known a method for producing a polymerized toner in which a polymerization reaction is performed in a state where a monomer of a binder resin raw material is dispersed to synthesize toner particles.

As a pulverization method for producing pulverized toner, a coarsely pulverized toner raw material is jetted together with a gas from a nozzle and pulverized by collision between raw material particles or collision with a collision plate, or a high-speed impact member. A mechanical crushing method of crushing is known. In the pulverized toner raw material, only particles having a desired particle diameter are selected by a classification step to obtain toner particles. As the toner for the developer for dry electrostatic image development, those having an average particle size of about 5 to 20 μm are usually used.

[0009]

In recent years, personalization,
With market demands such as space saving, downsizing of copiers, printers, etc. tends to be promoted. Further, in a full-color electrophotographic apparatus, it is necessary to arrange developing tanks for three or four colors in the apparatus, and further downsizing of the developing tank is required. However, the most commonly used two-component developing method conventionally requires a developing chamber for stirring a mixture of carrier particles and toner particles and a replenishing toner chamber for replenishing consumed toner. The function of controlling the mixing ratio of the toner and the carrier in the chamber is also required, and there are many problems from the viewpoint of downsizing and simplification.

In order to avoid these problems, the magnetic one-component method which does not use carrier particles has been widely used for personal use. However, although it is necessary to include a ferromagnetic component in the toner particles for one-component magnetic component, a colorless or light-colored ferromagnetic component is not generally known,
It is difficult to use magnetic single component development for full color development. Under such circumstances, a non-magnetic single-component developing method that does not use a ferromagnetic component or a magnet roller has been attracting attention as a full-color developing method. The non-magnetic one-component developing method includes a flying developing method and a contact developing method.

However, the problem of the non-magnetic one-component system occurs when the above-mentioned pressed developer layer thickness regulating member is used. That is, when a pressing force sufficient to form a uniform layer without toner scattering around is applied to the layer thickness regulating member, the toner is fused to the developer carrier or the layer thickness regulating member due to friction energy, or due to heat. Aggregation occurs, finely crushed, and fatal problems occur. If a hard toner having a high glass transition point or a high softening point is used to avoid these problems, the heat fixing performance is deteriorated, and a high temperature and a large amount of energy are required to sufficiently fix the toner on paper or the like.

However, from the viewpoint of energy saving,
Low temperature fixing is currently an essential performance requirement. It is essential to design the molecular weight distribution and thermal characteristics of the toner so that the toner is strong in the developing device which is relatively close to room temperature and easily melts in the fixing temperature range of about 90 ° C. or higher. As a measure from the apparatus side for realizing the non-magnetic one-component developing system without impairing the fixing property at low temperature, some creativity for obtaining high triboelectrification efficiency with weak friction energy has been realized. For example, a method in which a contact member such as a sponge roller that supplies toner to the developer carrying member is brought into contact with each other to increase the chance of friction, a method between the developer carrying member and the developer layer thickness regulating member, or a developer carrying member and the contact member. There is known a method of applying a potential difference between the two and injecting an electric charge into the developer passing therethrough.

If the developer cannot obtain a sufficient triboelectrification amount, undesirable phenomena such as toner scattering in the machine and fog on a white background occur. In addition, the non-magnetic 1-component is more likely to cause the "middle void" phenomenon than the 2-component. Hollow-out is an undesired phenomenon in which a portion where toner particles do not exist occurs in an image when a character or a line is formed. This "middle-out" phenomenon is likely to occur when the toner visualized on the member is transferred to another member, and more easily when the developer layer thickness is large. This occurs remarkably when transferring multicolor toners such as full-color development or when using an intermediate transfer member or the like.

The "ghost" phenomenon is more likely to occur in the nonmagnetic one component than in the two components. The ghost is a phenomenon in which an image that has already been obtained overlaps with an image that is to be produced in synchronism with the circumferential length of the image carrier, and an image that is not originally obtained becomes apparent. In order to solve these problems, it is considered preferable to use a toner having a shape close to a sphere so that the toner rolls well and the frictional force is not concentrated on some toner particles or only a part of the toner particles. As an example of using such a shape, a toner having a nearly spherical shape (JP-A-4-44056, JP-A-5-142857, etc.) and a polymerized toner having an almost spherical shape (JP-A-3-259161) are used.
Japanese Patent Laid-Open No. 4-225368, Japanese Patent Laid-Open No. 5-1
No. 65253, etc.) are known. Since the toner particles are triboelectrically charged with the development carrier while rotating in the developing device, a toner with a smooth surface close to a sphere has a wider contact surface than a toner with uneven shape and unevenness. It is also considered to be advantageous in terms of triboelectric charging property.

However, the polymerized toner often uses various additives in order to control the shape, the molecular weight, the dispersion of the pigment to be added, etc. in the manufacturing process, which is not preferable in terms of the charge control ability. In particular, environmental stability often causes problems such as deterioration of image quality due to high temperature and high humidity and low temperature and low humidity. On the other hand, the toner manufactured by the pulverization method is superior to the polymerized toner in terms of environmental stability, but has a non-uniform shape and is not preferable for preventing hollow defects. A method of producing a toner having a nearly spherical shape by a pulverization method (method using Kryptron Powder and Industrial Vol. 25 No. 5 (1993),
(p59, etc.) is also known, but still insufficient.

Under the above circumstances, it is difficult to give a uniform and sufficient triboelectrification amount to the developer with a weak friction energy that does not cause fusion, aggregation and fine pulverization. In addition to further improvement of the apparatus and physical improvement of the toner, improvement of the chemical composition of the developer capable of being sufficiently charged even with weak friction energy has been earnestly desired. A charge control agent is generally added as a compositional improvement for improving the triboelectrification characteristics, but in the case of a color toner, there is a limitation due to color, and the composition of the charge control agent is limited.

Further, in the case of producing by the above-mentioned pulverization method, it is necessary to uniformly disperse the charge control agent in the binder resin by melt-kneading, but in the case of full-color toner, the binder resin molecular weight distribution image is narrow and the viscosity suitable for melt-kneading is obtained. Since the temperature range is narrow, the dispersion of the charge control agent generally tends to be worse than that of a compound having a wide molecular weight distribution.
It is necessary to use a charge control agent that easily disperses under such conditions, or a charge control agent that exhibits excellent charging characteristics even if the dispersion is poor.

[0018]

SUMMARY OF THE INVENTION The present inventors have solved the above problems and, even when a developing device in which the friction energy applied to a developer is small is used, toner scattering, white background fogging,
As a result of intensive studies to obtain a developer with high image quality and long life without voids and ghosts, as a result, toner particles using an organic substance of a specific composition as a charge control agent were used, and a specific material was selected as a developing member. The present invention was achieved by using the one-component developing method used.

That is, the gist of the present invention is that the developer layer thickness regulating member is pressed against the developer carrying member, and the carrying member moves relatively to the regulating member, so that the toner particles are mainly composed of the toner particles. A one-component electrostatic developer forms a developer layer on the carrier in the process of passing through the pressing portion, and the developer on the carrier is applied to the electrostatic latent image holding member in the area facing the electrostatic latent image holding member. In the electrostatic developing method of transferring and visualizing, one of the surfaces of the developer carrying member and the layer thickness regulating member that come into contact with the toner particles is an inorganic material, and the toner particles are a boron-containing organic material represented by the following general chemical formula. The present invention resides in an electrostatic developing method characterized by containing and realizes good image quality.

[0020]

Embedded image

(In the formula, R ₁ and R ₄ each represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ each represent a substituted or unsubstituted aromatic ring. (Including condensed rings) and X ⁺ represents a cation.) Further, the developer contains 0.01 to 3% by weight of inorganic oxide fine particles having a specific surface area of 30 square meters / g or more as determined by a nitrogen adsorption method. By doing so, the thickness of the developer layer formed on the carrier can be stabilized and the life reliability can be improved.

In the present invention, the full-color developing device can be designed compact by using the non-magnetic one-component developing system. The present invention can realize good image formation in a state where the developer carrying member and the electrostatic latent image holding member are in contact with each other,
This is a developing method with less demands on the design accuracy of the apparatus.
The present invention can realize good image quality reproduction even in the state where no voltage is applied between the developer carrying member and the developer layer thickness regulating member, and the device can be simply designed.

The present invention is less likely to cause "middle void", is useful when the visualized developer is thick, and when an intermediate transfer member is used, and is effective for a full-color developing device. INDUSTRIAL APPLICABILITY The present invention is effective in a full-color developing method in which color superimposition is performed because "ghost" is less likely to occur in a developing method in which one of the surfaces of the developing device, which is in contact with the developer carrying member or the layer thickness regulating member, and toner particles is an inorganic Exert. The present invention is effective even when a binder resin having a weight average molecular weight of 5 times or less the number average molecular weight is used, and is effective for a full-color developing device that requires glossiness and transparency.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The toner used in the present invention is a fine powder containing a thermoplastic binder resin, a colorant, and if necessary, a charge control agent, a release agent and other substances dispersed therein. As the binder resin of the toner constituents, various known ones suitable for the toner can be used. For example, polystyrene, polychlorostyrene, poly-α-
Methylstyrene, styrene-chlorostyrene copolymer,
Styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-
Vinyl acetate copolymer, styrene-maleic acid copolymer,
Styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-phenyl acrylate Copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer) And styrene-phenyl methacrylate copolymers, etc.), styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers, and other styrene resins (styrene or homopolymers containing styrene substitutes). Or copolymer), vinyl chloride resin Rosin-modified maleic acid resins, phenol resins, epoxy resins, saturated polyester resins,
There are unsaturated polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, etc. Preferred resins include styrene resins, saturated or unsaturated polyester resins and epoxy resins.

As the binder resin used for full color which requires gloss and transparency, a non-crosslinkable, narrow molecular weight distribution resin is preferable among styrene resins and polyester resins. Is more preferred. Those having a weight average molecular weight of 5 times or less of the number average molecular weight are preferable, and those having a weight average molecular weight of 3 times or less are more preferable.

The non-crosslinkable polyester resin used in the present invention is obtained by polycondensation containing a divalent carboxylic acid monomer and a divalent alcohol monomer as main components. Examples of the dihydric alcohol monomer include ethylene glycol, diethylene glycol, triethylene glycol and 1,2-
Propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol and other diols, bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A, etc. Examples include etherified bisphenols and other dihydric alcohol monomers. The divalent carboxylic acid monomer is mainly composed of isophthalic acid, terephthalic acid, adipic acid, sebacic acid, diphenic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, and anhydrides or lower alkyl esters of these acids. Is mentioned.

The polyvalent carboxylic acid monomer having a valency of 3 or more and the polyvalent carboxylic acid monomer or polycarboxylic acid having a polyfunctional carboxylic acid used in the present invention can be used as long as the properties of the non-crosslinkable resin are not substantially lost, that is, the linear polymer is branched at most. You may add a polyhydric alcohol monomer etc. about 2 mol% or less. Examples of the trivalent or higher polycarboxylic acid include trimellitic acid, cyclohexanetricarboxylic acid,
Examples thereof include naphthalene tricarboxylic acid, butane tricarboxylic acid, hexane tricarboxylic acid, octane tetracarboxylic acid, anhydrides of these acids, and the like.
Examples of the trihydric or higher polyhydric alcohol monomer include trimethylolethane, trimethylolpropane, glycerin and pentaerythritol.

Further, it is not limited to use one by one, but two
More than one species may be used in combination. The weight average molecular weight and the number average molecular weight of the binder resin can be measured by gel permeation chromatography (hereinafter referred to as GPC) under the following conditions. That is, a solvent (tetrahydrofuran) is caused to flow at a flow rate of 1 ml / min at a temperature of 25 ° C., and 8 mg of a tetrahydrofuran sample solution having a concentration of 0.4 g / dl is injected as a sample weight for measurement. Further, in measuring the molecular weight distribution of a sample, the molecular weight distribution of the sample is included within the range in which the logarithm of the molecular weight and the count number of the calibration curve made by several kinds of monodisperse polystyrene standard samples are linear. Select the measurement conditions. In this measurement, the reliability of the measurement is based on the NB measured under the above measurement conditions.
S706 polystyrene standard sample (Mw = 288000,
Mw / Mn = 137,000, Mw / Mn = 2.11)
It can be confirmed that Mn becomes 2.11 ± 0.10.

Then, the softening point of the developer produced by using the binder resin is the value measured by the flow tester method,
It is preferably 150 ° C. or lower, more preferably 135 ° C. or lower. If it exceeds 150 ° C, sufficient low-temperature fixability cannot be obtained, and the fixing strength tends to deteriorate, such being undesirable. As a binder resin used for full color where gloss and transparency are required, 120
C. or less is preferable, and 110.degree. C. or less is more preferable. The lower the softening point is, the better the fixing property is, and it is preferable. However, as the softening point is lowered, the glass transition point described later is also lowered.

The glass transition temperature of the developer produced by using the binder resin is preferably such that the transition start (inflection point) when measured by a differential thermal analyzer is 50 ° C. or higher, and 60 ° C. or higher. Are more preferred. When the glass transition temperature is less than 50 ° C., thermal stability during long-term storage is poor,
There is a problem in use due to aggregation and solidification of the toner. 7 more
When the temperature is 0 ° C. or higher, there is a margin for fusing the toner and pulverizing the fine powder, but the softening point also increases as the glass transition point increases, so that the fixability tends to deteriorate.

As the colorant, any suitable pigment or dye can be used as long as it is conventionally used. For example, titanium oxide, zinc white, alumina white, calcium carbonate, navy blue, carbon black, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine dyes and pigments, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane dyes. , Anthraquinone dyes, monoazo and disazo dyes and pigments are used alone or appropriately mixed depending on the color of the corresponding toner.

The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development, and is, for example, 3 to 20 parts by weight based on 100 parts by weight of the binder resin. Preferably. The charge control agent used in this toner is

[0033]

Embedded image

(In the formula, R ₁ and R ₄ each represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ each represent a substituted or unsubstituted aromatic ring. (Including a condensed ring) and X ⁺ represents a cation). This organic substance is colorless and is suitable for use as a color toner. The addition amount of this organic substance is 0.
2 to 10% by weight is preferable, and 0.5 to 6% by weight is more preferable.

Further, it may be used in combination with another charge control agent. Other charge control agents include JP-A-3-37183.
Metal-containing azo dyes described in JP-B No. 2-16916, salicylic acid metal complexes described in JP-B-55-42752, etc., salicylic acid metal salts described in JP-A-63-163374, etc. Examples thereof include calixarene compounds containing no metal element described in Kaihei 5-119535. When used in combination for color, colorless or light-colored ones are preferable, and colorless or light-colored ones are known as salicylic acid metal complexes, salicylic acid metal salts, and calixarene compounds.

As a method of incorporating the above charge control agent into the toner, there are a method of adding it inside the toner and a method of adding it externally, but the case of internally adding it is general. In addition, known auxiliary agents that can be internally added to the toner for the purpose of improving thermal characteristics and physical characteristics can be used. For example, polyalkylene wax, paraffin wax, and higher fatty acid can be used as a release agent. , Fatty acid amides, and the like.
The amount added is 100 parts by weight of the binder resin,
0.1 to 10 parts by weight is preferable. In the case of using for full color where glossiness and transparency are required, use of a large amount of these auxiliaries may be harmful.

In the case of the method for producing a toner by a pulverization method, the above components may be kneaded with a kneader or the like, cooled, pulverized, and classified. The average particle size of the toner is preferably 5 to 20 μm. Generally, a method using a Coulter counter is widely used for the particle diameter of the toner. The average particle size of the toner used in this invention is Coulter Counter TA
A toner particle was dispersed in Isoton using an II-type 100 μm aperture, and the toner particle size distribution was measured using channels 3 to 16 and determined by volume averaging.

The softening point of the toner was measured using the flow tester method. Flow tester (Shimadzu CFT50
In 0), using a nozzle with a diameter of 1 mm and a length of 1 mm,
The heating element is set to 80 ° C. and 1 g of toner is added. Press the plunger lightly and heat it for 300 seconds, then 20k
A pressure of g / cm 2 is applied and the temperature is raised at a rate of 6 ° C./min. The toner is softened by the temperature rise and is pushed out from the nozzle, and the plunger is lowered. The temperature at which the plunger falls from the start to the end of the descent is the softening point.

The glass transition point of the toner is about 20 m using a differential thermal analyzer (DT-30 manufactured by Shimadzu Corporation).
g into the sample cell and set in the measuring section, once at 10 ° C /
After heating to 100 ° C. at a temperature rising rate of 10 minutes and cooling to room temperature, the temperature is raised again at 10 ° C./minute, and tangent lines are drawn from smooth curve portions before and after the inflection temperature portion of the DTA curve at this time, The intersection of these tangents is taken as the glass transition point.

Even in the case of a developer containing a toner as a main component and inorganic oxide fine particles or a fatty acid metal salt mixed therein, the softening point and the glass transition point are dominated by the thermal characteristics of the toner. The difference between the case of measurement by the method (1) and the case of measurement by the developer as the mixture is within the measurement error range. In the developing method using the above-mentioned toner particles alone or the developer to which the inorganic oxide fine particles are added, white background fog is likely to occur and the image quality is poor, and more toner adheres to the white background, resulting in higher toner consumption. Will end up. By adding the fatty acid metal salt, the fog on the white background is reduced, and the toner consumption can be reduced.

The fatty acid metal salt used in the present invention is preferably a saturated or unsaturated fatty acid metal salt having 8 to 35 carbon atoms. As the metal salt, lithium, sodium, potassium, copper, rubinium, silver, magnesium, calcium, zinc, strontium, cadmium, barium, mercury, aluminum, chromium, tin, titanium, zirconium, lead, manganese,
Including iron, cobalt, nickel salts and mixtures thereof,
It is not limited to these. The particle size of the fatty acid metal salt powder before addition is usually about 0.2 to 30 μm, but it is not particularly limited because it has a crushing effect when mixed with toner particles. However, it is more preferable that the amount of coarse powder is small and the particle size is small because uniform dispersion is easy at the time of mixing. The amount of the fatty acid metal salt added depends on the particle size, etc.
0.01-5 parts by weight, more preferably 0.05-1.
2 parts by weight exerts a remarkable effect. Among the fatty acid metal salts, zinc stearate is particularly preferable.

The inorganic oxide fine particles having a specific surface area of 30 square meters / g or more added in the present invention include silicon, titanium, aluminum, magnesium, iron, zinc,
Oxides such as cerium and their composite oxides can be used. The surface of these may be surface-treated with a silane coupling agent, a titanium coupling agent, silicone, or other resin. Examples of conventionally known fine particle inorganic oxides include silica (R972 from Nippon Aerosil Co., Ltd., Taranox 500 from Gunze Sangyo Co., Ltd.), titania (Idemitsu Kosan I
Inorganic oxide fine particles such as T-S), alumina (aluminum oxide C of Nippon Aerosil Co., Ltd.), magnesia (gas phase method high-purity ultrafine powder magnesia 100A manufactured by Ube Industries, etc.), iron oxide (Sicopur FF4098 manufactured by BASF, etc.) Are known. The addition amount is 0.01 in the developer.
~ 3% by weight, more preferably 0.03 to 1.5% by weight
By adding it, the effect is remarkably exhibited.

The specific surface area measured by the nitrogen adsorption method was Shimadzu Micromeritics Flowsorb 2300, and an appropriate amount of sample was put into the cell and degassing was performed at 200 ° C. for 10 to 20 minutes to obtain the specific surface area (square m / g). taking measurement. If degassing at 200 ° C is not possible due to possible decomposition of the sample, degas at a temperature below that value and repeat the measurement on the same sample. Use the measured value when the value is stable. .

It is preferable that a predetermined amount of the toner, the metal salt of fatty acid and the fine particles of the inorganic oxide be blended and stirred and mixed by a high speed stirrer or the like which gives a shearing force to the powder such as a Henschel mixer or a super mixer. At this time, since heat is generated inside the external additive machine and aggregates are easily generated, it is preferable to adjust the temperature by means such as cooling the periphery of the container part of the external additive machine with water. The internal material temperature is set to be equal to or lower than the glass transition temperature of the resin, and a control temperature of about 10 ° C. or lower, particularly a control temperature of 15 ° C. or lower is preferable. In practice, the material temperature may be regarded as the temperature inside the tank of the external addition machine.

A developing method will be described by taking the developing device of FIG. 1 as an example. The developer carrier 1 used in the present invention usually has a cylindrical or cylindrical surface as the carrier surface. The material may be either elastic or rigid. The surface may be provided with an appropriate surface roughness for the purpose of improving the transportability of the developer. Further, it is necessary to consider a material capable of obtaining an appropriate frictional charge with the toner particles. As the material of the surface, metal such as stainless steel and aluminum, plastic such as phenol resin, silicon, and rubber material such as urethane rubber are used.

Developer layer thickness regulating member 2 used in the present invention
Examples include various types such as a rectangular rod-shaped rigid body, a protrusion-shaped elastic body, a leaf spring that uses the surface or tip of a leaf spring, a roller, or a combination thereof. The developer layer thickness regulating member 2 is linearly pressed against the developer carrier by its own elastic force, the elastic force of the developer carrier 1, an external force, or a combined force thereof.

As the surface material of the layer thickness regulating member, metals such as stainless steel and aluminum, and rubber materials such as silicon and urethane are used. There are various electrical characteristics such as when applying a voltage to an insulator or conductor, or a conductor that is electrically not connected to anything and floats. In the case of the body or the case where the electric conductor is not applied with the voltage, the "white background fog" is likely to occur due to the oppositely charged toner, and the present invention exerts a remarkable effect. By relatively moving the developer carrier relative to this linear pressing so as to slide in a direction perpendicular to the linear carrier, the developer particles pass while spreading the pressing portion, and the developer particles are evenly coated on the developer carrier 1. Form the layers. The thickness of the developer layer and the charge amount of the toner are controlled by the form, pressure, composition, and applied voltage of the pressing portion. Globally, the higher the pressure, the smaller the developer layer thickness applied and the higher the amount of charge, but the morphology, composition, and applied voltage are complicated physical and chemical phenomena and cannot be generally discussed.

When toner particles containing a boron-containing organic material used in the present invention are used, "ghost" is reduced due to the combination of one of the surface materials of the developer carrying member and the developing layer thickness regulating member being an inorganic material. Preferably, when the developer carrier surface material is a metal, "ghost" is significantly reduced. The electrostatic latent image holding member 3 used in the present invention is a photoreceptor having a layer of selenium, an organic photosensitive material or the like on the surface of a conductive substrate or a master having an insulating layer on the surface of the conductive substrate. Is used to form an electrostatic latent image pattern by electrostatic charge distribution on the surface. As a general form used in a copying machine or a laser printer, a cylinder made of metal such as aluminum or a sheet of a resin film on which a thin film of aluminum is formed and coated with a photosensitive material is used. When an organic photosensitive material is used as the photosensitive material, the photosensitive layer has a relative dielectric constant of about 1 to 5 and is generally used with a layer thickness of about 10 to 50 μm.

In the image forming step, a latent image having an electrostatic charge distribution is formed on the electrostatic latent image holding member 3 by uniform charging and exposure procedures according to the generally used principle of xerography. At this time, the maximum potential on the electrostatic latent image holding member 3 is
About 100 to 1200 V in absolute value based on the conductive base material,
More preferably, it is controlled to be about 300 to 900V.

On the other hand, as described above, the developer carrying member 1 has
The developer is applied by the developer layer thickness regulating member 2. 500 V is applied between the developer carrying member 1 and the developer layer thickness regulating member 2 when no voltage is applied or when they are short-circuited to have the same potential.
There are cases where the voltage below is applied. Further, the developer supplying means 4 may be provided on the upstream side of the developer layer thickness regulating member 2 in the relative movement direction of the developer carrier 1.

As the developer supplying means 4, a means is used in which the developer is positively directed toward the carrier, in addition to the force of the developer adhering to the developer carrier 1 due to its own weight and fluidity. For example, a method may be used in which a developer is contained in a sponge-like or brush-like member and rubbed against the developer carrying member 1. The friction at this time may be used to accelerate the triboelectrification of the developer.
A conductive material may be used for the developer supplying means 4, and a voltage may be applied between the developer and the carrier so that the developer applies an electrostatic force toward the carrier. Further, since the roller-shaped endless developer carrier 1 is generally used, the carrier 1 to which the remaining developer after the development on the latent image holding member 3 adheres returns to the portion of the supply means 4. It also comes as a cleaning means. On the contrary, in order to positively utilize the effect, a voltage may be applied so that a force is applied in a direction in which the developer is separated from the carrier 1. Also, an alternating electric field may be applied for the purpose of both cleaning and supply, or for the purpose of charging the developer.

When the developing device having the configuration shown in FIG. 1 is used, the developer leak seal member 5 is generally attached because the developer may leak from the lower gap of the developer carrying member 1. Through the above steps, the electrostatic latent image holding member 3 having a latent image formed thereon is opposed to the developer carrying member 1 having a developer layer formed thereon, and at least toner particles in the developer are transferred to visualize the latent image.

At this time, in flight development, 50 to 50
A gap of 0 μm is formed and transferred by electrostatic force. In the case of contact development, the toner particles are pressed through the developer layer, and the toner particles corresponding to the latent image pattern are transferred by electrostatic force. It is common to maintain the potential of the carrier at a potential between the latent image potential to which the toner is to be transferred and the latent image potential to be the white background. In the case of a monochromatic copying machine or laser printer, the toner transferred to the latent image pattern is generally further transferred to a transfer material such as paper or film.

In the case of full-color development, multicolor transfer may be repeated on the transfer material, but the intermediate transfer member 7 is used.
The full-color image may be visualized by repeating the transfer of each color from the electrostatic latent image holding member onto the intermediate transfer member 7, overlapping the colors, and then transferring the colors onto the transfer material 8 at once. In these transfer steps, the surface of the transfer source and the surface of the transfer destination are brought into contact with each other,
Generally, a method of applying an electric charge from the back surface by corona discharge, a method of pressing a conductive transfer roller 9 to apply a voltage, and the like are common. In the case of a transfer process in which a pressure such as roller transfer is applied, the above-mentioned “middle-out” is likely to occur. In addition, the thicker the developer layer to be transferred, the more easily "middle-out" occurs. In such a case, the present invention exerts a remarkable effect. The toner transferred onto the transfer material is generally fused and fixed by heat in a fixing device.

[0055]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. In addition, in the following Examples and Comparative Examples, simply saying “part” means “part by weight”.

Example 1 Black, cyan, magenta, and yellow toners were manufactured according to the following formulation and tested.

[0057]

[Table 1]

Was mixed with a twin-screw kneading extruder, pulverized and classified to obtain toner particles having an average particle size of about 9 microns. Four
The softening points of the color toners were in the range of 108 to 110 ° C, and the glass transition points thereof were in the range of 62 to 65 ° C. To 100 parts of each toner particle, 1.0 part of zinc stearate (ACF manufactured by SYNPRO, USA) and silica fine powder (R972 manufactured by Nippon Aerosil Co., Ltd., specific surface area: 120 square meters)
/ G, the surface of which is hydrophobized by a dimethylsilane group) and 0.3 parts thereof were mixed with a Henschel mixer to obtain four color developers.

A full-color laser printer Phaser 540JS made by Sony Tektronix Co., Ltd. was filled with a developer of each color in a developer carrier only of the developer carrier of the developer, and an actual copying test was conducted. This printer uses a non-magnetic 1-component development system,
The surface material of the developer layer thickness regulating member is rubber, and no voltage is applied to the developer layer thickness regulating member. An OPC photoconductor sheet is used as the electrostatic latent image holding member, and a device of a type that forms an image on a transfer material such as paper or an OHP sheet by a roller transfer method after transferring an image of four colors to an intermediate transfer member. Is. As a result of the actual copying test, good images with less "white background fog" and "blurring" and less "ghost" were obtained from the initial 4000 sheets for all four color toners.

Example 2 For magenta toner, a magenta developer was procured in the same manner as in Example 1 except that the compounding amount of the charge control agent A was changed to 1 part. This magenta developer and the black procured in Example 1,
Using cyan and yellow developers, a developing device modified in the same manner as in Example 1 was used to carry out actual copying tests up to 3000 sheets. Compared with the magenta developer of Example 1, "white background fog"
"Cutout" and "ghost" were slightly inferior, but good image quality with no problem was maintained from the initial stage to 3000 sheets.

Example 3 With respect to the magenta toner, a magenta developer was procured in the same manner as in Example 1 except that the compounding amount of the charge control agent A was changed to 2 parts. This magenta developer and the black procured in Example 1,
Using cyan and yellow developers, a developing device modified in the same manner as in Example 1 was used to carry out actual copying tests up to 3000 sheets. The good image quality of the same level as that of the magenta developer of Example 1 was maintained from the initial stage to 3000 sheets.

Example 4 With respect to magenta toner, a magenta developer was procured in the same manner as in Example 1 except that the compounding amount of the charge control agent A was changed to 5 parts. This magenta developer and the black procured in Example 1,
Using cyan and yellow developers, a developing device modified in the same manner as in Example 1 was used to carry out actual copying tests from the initial stage to 3000 sheets. Compared with the magenta developer of Example 1, "white background fog", "middle void", and "ghost" were slightly inferior, but good image quality with almost the same level of problem as in Example 2 was maintained up to 3000 sheets.

Example 5 Using the same developer as in Example 1, a full-color laser printer Phaser 540 manufactured by Sony Tektronix, Inc.
Only the layer thickness regulating member of the JS developing device was modified into stainless steel, and the developing device of each color was filled with the developing device. As a result of the actual copying test, good images with less "white background fog" and "blurring" and less "ghost" were obtained from the initial 4000 sheets for all four color toners.

COMPARATIVE EXAMPLE 1 Evaluation was carried out in the same manner as in Example 1 except that the developer carrying member was made of aluminum and the developer layer thickness regulating member was made of stainless steel as a developing device. As a result, a toner layer on the developer carrying member was scarcely formed, and a faint image having a low density was obtained.

Comparative Example 2 The same evaluation as in Example 1 was carried out except that a developing device in which the developing carrier was covered with rubber and the developing layer thickness regulating member was covered with rubber was used as the developing device. As a result, the "fog on white background" and the "void" were good, but "ghost" occurred.

[0066]

According to the present invention, it is possible to obtain a developing method with a long life and high image quality, which is free from toner scattering, white background fogging, hollow defects, ghosts, and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a developing method that can be used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developer carrying member 2 Developer layer thickness regulating member 3 Electrostatic latent image holding member 4 Developer supplying means 5 Developer leak prevention seal member 6 Electrostatic developer 7 Intermediate transfer member 8 Transfer material 9 Transfer roller

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Claims (8)

[Claims] 1. A one-component electrostatic developer containing toner particles as a main component when a developer layer thickness regulating member is pressed against a developer carrier and the carrier moves relatively to the regulating member. Forms a developer layer on the carrier in the step of passing through the pressing portion, and transfers the developer on the carrier to the electrostatic latent image holding member in the area facing the electrostatic latent image holding member to visualize the developer. In the electrostatic development method, one of the surfaces of the developer carrying member and the layer thickness regulating member that contact the toner particles is an inorganic material, and the toner particles contain a boron-containing organic material represented by the following general chemical formula. Characteristic electrostatic development method. Embedded image (In the formula, R ₁ and R ₄ each represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ each represent a substituted or unsubstituted aromatic ring (condensed ring). Is also included), and X ⁺ represents a cation.) 2. The carrier surface with which the toner particles are in contact is an inorganic material, the boron-containing organic material contained in the toner particles is represented by the following chemical formula, and the content of the boron-containing organic material in the toner particles is 0. 2. The electrostatic developing method according to claim 1, wherein the amount is 2 to 10% by weight. Embedded image 3. The developer contains 0.01 to 3 inorganic fine particles having a specific surface area of 30 square meters / g or more as determined by a nitrogen adsorption method.
3. The electrostatic development method according to claim 1, wherein the electrostatic development is carried out by weight. 4. The electrostatic developing method according to claim 1, wherein the one-component electrostatic developer is a non-magnetic one-component developer. 5. The developer layer carried on the developer carrying member is in contact with the electrostatic latent image holding member in a region where the developer carrying member and the electrostatic latent image holding member are opposed to each other. 5. The electrostatic developing method according to any one of items 4 to 4. 6. A voltage is not applied between the developer layer thickness regulating member and the developer carrying material.
The electrostatic development method according to item. 7. The developer on the electrostatic latent image holding member visualized by the electrostatic developing method according to claim 1 is transferred to an intermediate transfer member, and then from the intermediate transfer member to a transfer material. An electrostatic development method characterized by transfer. 8. The electrostatic development according to claim 7, which is a multicolor developing method in which two or more color developers are transferred onto the intermediate transfer member and then transferred from the intermediate transfer member to the transfer material. Development method.