JP2000047418A - Toner and developing device with the toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner with better fluidity and an electrification property by setting the average grain size of the whole toner and the average grain size of the toner made of base grains with the density less than the prescribed external filler density to specific values respectively, and satisfying a specific relation between the specific values. SOLUTION: In a toner constituted of many base grains (C) 8 and many external fillers (SiO2) 9 stuck to the base grains 8, the average grain size D1 of the whole toner and the average grain size D2 of the toner constituted of base grains with the density less than the prescribed external filler density are set to satisfy the relation D1/D2<2. When this relation is set, the grain size of the toner with the density less than the prescribed external filler density can be practically increased. The toner excellent in fluidity and an electrification property can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of toner for developing an electrostatic latent image on a latent image carrier, and a method of carrying the toner on the toner carrier to move the toner toward the latent image carrier. Conveyed, belongs to the technical field of a developing device that develops an electrostatic latent image on a latent image carrier by using the conveyed toner, and particularly, the technical field of toner having excellent fluidity and chargeability, and And a developing device provided with a toner regulating means for uniformly charging the toner.

[0002]

2. Description of the Related Art As shown in FIG. 5, a one-component developing apparatus using a conventional general one-component developer for developing an electrostatic latent image on the surface of a latent image carrier with a one-component developer made of toner. In 1, the toner as a one-component developer in the toner storage unit 2 is transported to a toner supply member 4 by a toner transport unit 3, and the toner T is further supplied to the developer as a developer carrier by a toner supply member 4. The developer is supplied to the carrier 5 and is carried on the surface of the developer carrier 5. Further, the toner T on the developer carrier 5 is formed into a uniform thin layer by a developer regulating member 6 composed of a toner regulating blade, is uniformly charged, and is conveyed toward the latent image carrier 7. With the toner T, the electrostatic latent image on the latent image carrier 7 is developed and visualized.

The toner T used in the conventional general developing device 1 is used when the toner T on the developer carrier 5 is uniformly thinned and uniformly charged by the developer regulating member 6. The toner passes through the space between the carrier 5 and the developer regulating member 6 and is conveyed toward the latent image carrier 7.

However, in order to obtain a large number of images at a high speed in the one-component system, when the developer carrier 5 is rotated at a high speed with the developer regulating member 6 in contact, FIG. As shown in (2), toner T 'that cannot pass through between the developer carrier 5 and the developer regulating member 6 is generated,
The toner T 'may adhere to a contact portion (hereinafter, also referred to as a nip portion) 6a of the developer regulating member 6 with the developer carrier 5. Further, since the toner T 'thus fixed causes unevenness in toner conveyance by the developer carrier 5, in the conventional one-component developing method, an image obtained tends to have a vertical stripe-shaped image density unevenness. .

Since the toner T passes through the gap between the developer carrier 5 and the developer regulating member 6 to form a uniform thin layer, is uniformly charged, and is conveyed toward the latent image carrier 7, the toner T T is required to have good fluidity and good chargeability. Therefore, as shown in FIG. 7, the conventional toner T has silica (Si) on the surface of the base particles 8 made of resin (carbon: C).
An external additive 9 made of O ₂ ) is adhered to ensure the fluidity and chargeability.

[0006]

However, the particle size of each particle of the toner T is not only large, medium, and small, but also the adhesion of the external additive 9 to the base particles 8 is uniform and sufficient. It is not always done. Therefore, the toner T having an external additive concentration lower than the predetermined concentration and having poor fluidity and chargeability is formed. When the toner T is conveyed to the nip portion 6a of the developer regulating member 6, the toner T is similarly developed. The toner cannot pass through between the developer carrier 5 and the developer regulating member 6, and is fixed to the nip portion 6 a of the developer regulating member 6.

The adhesion of the toner T 'to the developer regulating member 6 is considered to occur as follows. That is, the toner T of a small particle diameter having a low external additive coverage less than the predetermined concentration of the external additive 9 adheres to the contact portion between the developer regulating member 6 and the developer carrier 5 by physical adhesion. Later, this toner T
Is repeatedly rubbed between the developer regulating member 6 and the developer carrier 5 moving at a high speed, thereby receiving thermomechanical stress. However, the toner T having a small particle diameter having a low external additive coverage tends to be thermally deformed due to a small heat capacity due to its small volume, and also has a low external additive coverage due to toner flow due to a low external additive coverage. There is a disadvantage that movement is difficult to occur. For this reason, the toner T having a small particle diameter having a low external additive coverage does not disperse the stress to the surroundings when subjected to thermomechanical stress from the outside, and causes a change in shape itself. As a result, the toner T whose shape has changed is bonded to the adjacent toner or the surface of the developer regulating member 6, so that the toner T is fixed. Then, due to the fixed toner, unevenness of toner conveyance occurs as in the above-described case, and image density unevenness having a vertical stripe shape occurs.

[0008] The present invention has been made in view of such problems, and an object of the present invention is to provide a toner having better fluidity and chargeability. Another object of the present invention is to prevent toner from sticking to the toner regulating means,
An object of the present invention is to provide a developing device capable of suppressing occurrence of toner conveyance unevenness.

[0009]

In order to solve this problem, a toner according to the present invention is a toner comprising a large number of base particles and a large number of external additives respectively attached to these base particles. When the average particle diameter of the entire toner is D1 and the average particle diameter of the toner composed of the base particles less than the predetermined external additive concentration is D2, the average particle diameter of the entire toner and the mother particle not satisfying the predetermined external additive concentration are not satisfied. It is characterized in that the average particle diameter of the toner composed of particles is set so as to satisfy the relationship of D1 / D2 <2.

According to a second aspect of the present invention, there is provided a toner regulating device for regulating at least a developer carrying member for carrying a developer and a conveyance of the toner such that a uniform thin layer of the toner is formed on the developer carrying member. Means, wherein the toner according to claim 1 is used as a developer.

[0011]

In the toner according to the first aspect of the present invention, the ratio of the average particle diameter of the toner composed of the base particles having a concentration less than the predetermined external additive concentration to the average particle diameter of the entire toner is adjusted. , Y or more, the particle size of the toner that does not reach the predetermined external additive concentration is substantially increased. Then, even if the toner is restricted by the toner restricting means by physical adhesion at the contact portion between the toner restricting means and the developer carrying member and in the vicinity thereof, the toner restricting means moves by the toner flow, and is further restricted by the toner restricting means. Even if the toner is subjected to thermomechanical stress due to repeated rubbing between the toner carrier and the developer carrier moving at a high speed, the toner has a large heat capacity in accordance with the large particle size, so that the shape change of the toner is suppressed. As a result, even if the developer carrier that moves at a high speed is brought into contact with the toner regulating unit via the toner, the phenomenon that the toner is bonded to the adjacent toner particles or the surface of the toner regulating unit does not occur. It is difficult for toner to adhere to the means. Therefore, the uneven conveyance of the developer is prevented.

Further, in the developing device according to the second aspect, since the toner according to the first aspect is used as the developer, it is difficult for the toner to adhere to the toner regulating means, so that the durability of the developing device is improved. However, the developing device of the present invention can be repeatedly used for a long time only by replenishing the developer.

As described above, in the toner and the developing device of the present invention, the unevenness in the transport of the developer by the developer carrier is eliminated, so that the image density unevenness in the form of vertical stripes due to the unevenness in the transport is eliminated, and the image quality is improved. .

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an example of a conventional toner analysis method used for analyzing the state of adhesion between a mother particle and an external additive of a toner, which is an example of an embodiment of the toner according to the present invention.

First, in the toner of this example, the toner T
As a method of analyzing the adhesion state between the mother particles and the external additive,
Electrographic Society of Japan Annual Conference (95 times in total), “Japan Hardc
opy'97 "Paper Collection," New External Evaluation Method-Toner Analysis by Particle Analyzer-", Toshiyuki Suzuki, Toshio Takahara, sponsored by the Society of Electrophotography, July 9-11, 1997 Is adopted.

In this toner analysis method, particles of toner T formed by adhering an external additive made of silica (SiO ₂ ) to the surface of base particles made of resin (C) are introduced into plasma. This is a method of performing elemental analysis by exciting toner T particles and obtaining an emission spectrum as shown in FIG. 1 accompanying the excitation.

In FIG. 1, the horizontal axis of the emission spectrum indicates the time axis. First, as shown in FIG. 1A, when the toner T particles obtained by adhering the external additive (SiO ₂ ) to the resin base particles (C) of the toner T are introduced into the plasma, the mother particles (C) and the outer particles are formed. The additive (SiO ₂ ) emits light. At this time,
Since the base particles (C) and the external additive (SiO ₂ ) are simultaneously introduced into the plasma, the base particles (C) and the external additive (SiO ₂ ) are introduced.
₂ ) and emit light simultaneously. Thus, when the base particles (C) and the external additive (SiO ₂ ) emit light simultaneously, it is said that the base particles (C) and the external additive (SiO ₂ ) are synchronized. In other words, the state where the base particles (C) and the external additive (SiO ₂ ) are synchronized indicates a state where the external additive (SiO ₂ ) is attached to the base particles (C).

Further, as shown in FIG.
Base particles (C) or base particles (C) to which iO ₂ ) does not adhere.
When the external additive (SiO ₂ ) released from the gas is introduced into the plasma, the mother particles (C) and the external additive (S
iO ₂ ) emits light, but at this time, the base particles (C) and the external additive (SiO ₂ ) are introduced into the plasma at different times.
Light emission occurs at a time different from ₂ ) (for example, when the base particles are introduced into the plasma before the external additives, the base particles emit light first, and thereafter the external additives emit light after a delay).

As described above, the base particles (C) and the external additives (Si
O ₂ ) emits light at different times from each other,
It is said that the base particles (C) and the external additive (SiO ₂ ) are not synchronized (that is, asynchronous). In other words, the state in which the base particles (C) and the external additive (SiO ₂ ) are asynchronous is as follows:
This means that the external additive (SiO ₂ ) is not attached to the base particles (C).

Further, in FIG. 1, the height of the light emission signal indicates the intensity of the light emission, and the intensity of the light emission is not the size or shape of the particle, but the element contained in the particle ( C, SiO ₂ ). In order to express the emission intensity of the element as the size of the particles, when light emission of the base particles (C) and the external additive (SiO ₂ ) is obtained as shown in FIG. 2, these base particles (C) and the external additive assuming particles (SiO ₂₎ was only truly spherical, it is expressed as particle diameter thereof of the mother particle (C) and the external additive (SiO _2). The true spherical particles at this time are called equivalent particles,
The particle size is called an equivalent particle size. Since the external additive is very small, the particles cannot be detected one by one. Therefore, the emission signal of the detected external additive is added to be converted into one equivalent particle and analyzed. .

When the equivalent particle size of the equivalent particles obtained by the respective emission spectra of the base particles and the external additives is plotted for each particle of the toner T, the equivalent particle size of the toner particles as shown in FIG. A distribution map is obtained.

In FIG. 3, the horizontal axis represents the equivalent particle size of the base particles (C), and the vertical axis represents the equivalent particle size of the external additive (SiO ₂ ). The equivalent particles on the horizontal axis represent the external additive (Si
O ₂ ) represents the asynchronous parent particles (C) without attachment. In this case, the base particles (C) to which the external additive less than the predetermined external additive concentration is attached are also shown on the horizontal axis, and are regarded as asynchronous parent particles (C). The equivalent particle on the vertical axis is the asynchronous external additive (S) released from the base particle (C).
iO ₂ ). Further, the equivalent particles not on the horizontal axis and the vertical axis represent the synchronous toner T in which the external additive (SiO ₂ ) is attached to the base particles (C). Thus, the external additive (Si) to the base particles (C) of the toner T
O ₂ ) adhesion is analyzed.

Incidentally, the toner T used in the image forming apparatus of this embodiment may be either negative polarity or positive polarity toner. The base particles are composed of at least a colorant, a charge control agent, and a resin, and may further include a dispersant, a release agent (WAX), a magnetic material, and other additives.

Examples of the base particles include polystyrene and copolymers such as hydrogenated styrene resin, styrene / isobutylene copolymer, ABS resin, ASA resin, AS resin,
AS resin, ACS resin, AES resin, styrene / P-chlorostyrene copolymer, styrene / propylene copolymer,
Styrene-butadiene cross-linked polymer, styrene-butadiene-chlorinated paraffin copolymer, styrene-allyl-
Alcohol copolymer, styrene / butadiene rubber emulsion, styrene / maleic ester copolymer, styrene / isobutylene copolymer, styrene / maleic anhydride copolymer, acrylate-based resin or methacrylate-based resin and its copolymer, Styrene / acrylic resin and its copolymer, for example, styrene / acrylic copolymer, styrene / diethylamino / ethyl methacrylate copolymer, styrene / butadiene / acrylic ester copolymer, styrene / methyl methacrylate copolymer Styrene / n-butyl methacrylate copolymer, styrene / methyl methacrylate / n-butyl acrylate copolymer, styrene / methyl methacrylate / butyl acrylate / N- (ethoxymethyl) acrylamide copolymer Styrene / glycidyl methacrylate copolymer, styrene / butadiene / dimethyl / aminoethyl methacrylate copolymer, styrene / acrylate / maleate copolymer, styrene / methyl methacrylate / 2-ethylhexyl acrylate Styrene-n-butylarylate-ethyl glycol methacrylate copolymer, styrene-n-
Butyl methacrylate / acrylic acid copolymer, styrene / n-butyl methacrylate / maleic anhydride copolymer, styrene / butyl acrylate / isobutyl maleic acid half ester / divinylbenzene copolymer, polyester and its copolymer, Polyethylene and its copolymer, epoxy resin, silicone resin, polypropylene and its copolymer, fluorine resin, polyamide resin, polyvinyl alcohol resin, polyurethane resin, polyvinyl butyral resin, etc. blended one or more kinds Can be used.

Examples of the coloring agent include carbon black, spirit black, nigrosine, rhodamine, triaminotriphenylmethane, cation, dioxazine, copper phthalocyanine, berylen, azo, gold-containing azo pigment, azochrome complex, carmine, Benzidine,
Solar Pure Yellow 8G, quinacridone, polytungstophosphoric acid, induslen blue, a sulfonamide derivative and the like can be used.

As the charge control agent, an electron-accepting organic complex, chlorinated polyester, nitrophenic acid, quaternary ammonium salt, pyridinyl salt and the like can be used. As the release agent, polypropylene wax, polyethylene wax or the like can be used.

As the dispersant, metal soap, polyethylene glycol and the like can be used. Other additives include
Zinc stearate, zinc oxide, cerium oxide and the like can be used.

As the magnetic agent, Fe, Co, Ni, C
Metal powder such as r, Mn, Zn, etc., Fe ₃ O ₄ , Fe ₂ O ₃ , Cr
_An alloy or the like which exhibits ferromagnetism by heat treatment such as a metal oxide such as ₂ O ₃ or ferrite, or an alloy containing manganese and an acid can be used, and a preliminary treatment such as a coupling agent may be performed in advance. These are formed into mother particles by a general kneading and pulverizing method, a spray-dry method, a polymerization method, or the like.

Various external additives whose surfaces have been subjected to a hydrophobic treatment can be used as the external additives. For example, fine particles of metal oxides such as silica, aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, and chromium oxide, fine particles of nitride such as silicon nitride, fine particles of carbide such as silicon carbide, calcium sulfate, and barium sulfate And inorganic fine particles such as fine particles of metal salts such as calcium carbonate and composites thereof, and organic fine particles such as acrylic fine particles. Further, as these surface treatment agents, silane coupling agents, titanate coupling agents, fluorine-containing silane coupling agents, silicone oils, and the like can be used. The hydrophobicity of the external additive treated with these treating agents is 60% by the conventional methanol method.
The above are preferred. If the temperature is lower than this, the chargeability and the fluidity are likely to be reduced due to the adsorption of moisture during the high temperature and high humidity, which is not preferable. The particle size of the external additive is preferably from 0.001 to 1 μm from the viewpoint of transportability and chargeability. The additive amount of the external additive is preferably 0.1 to 5% by weight based on the toner base particles. When the amount is further increased, the probability that the external additive is not synchronized with the toner increases, secondary aggregation of the external additive occurs frequently, and the charging property is reduced and the transport streak is increased. Become.
Also, the external additive is not limited to one kind,
Mixtures of more than one type can also be used.

The mother particles and the external additives are dry-mixed with a high-speed fluid mixer such as a Henschel mixer or a Papen-Meier or a mixer such as a mechanochemical method and adhered.

The developer carrying member used in the developing device in the image forming apparatus of this embodiment may be any of magnetic, non-magnetic, conductive, insulating, metal, rubber, resin, etc. which can be formed as the developer carrying member. Anything can be used. For example, in terms of material, aluminum, nickel,
Metals such as stainless steel, natural rubber, silicone rubber, urethane rubber, butadiene rubber, chloroprene rubber, neoprene rubber, rubber such as NBR, styrene resin, vinyl chloride resin, polyurethane resin, polyethylene resin, methacryl resin, nylon resin, etc. Can be used.
It goes without saying that these materials can be used even if they are coated on the upper layer. In that case, as the coating material,
Polyethylene, polystyrene, polyurethane, polyester, nylon, acrylic and the like can be used. In addition, as a form, inelastic body, elastic body, single layer, multilayer, film,
Everything such as rollers can be used. Also,
The surface roughness of the developer carrying member is set to Rz1 to 10 μm in order to secure toner transportability.

Further, as a material of the toner supply member used in the developing device in the image forming apparatus of this embodiment, it is preferable to set an elastic body to stabilize the contact of the developer carrier. In this example, as the material of the toner supply member, polyurethane foam, polystyrene foam, polyethylene foam, polyester foam, ethylene propylene foam, nylon foam, silicone foam, and the like can be used. Note that the foaming cell of the toner supply means can use either a single cell or a continuous cell, but a single cell is preferable. This means that if the foam cell is open cell,
This is because the toner enters the inside of the foam cell of the supply unit, and eventually causes the toner to aggregate in the inside and the surface layer portion, which causes a decrease in toner transportability and a transport streak in the regulating portion. Therefore, single cells are preferred. Hardness is 1
A roller of 0 ° to 40 ° (measured by Asker C hardness tester) can be used, but a roller of 35 ° to 40 ° having a large scraping effect of the residual toner on the developer carrying member is most preferable. The resistance value is 10 ³ to 10 ⁷ Ωcm (volume resistance value).
Can be used.

In this embodiment, a foam material is used, but it goes without saying that a rubber material having elasticity may be used. Specifically, conductive agents such as carbon are dispersed in silicon rubber, urethane rubber, natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, butyl rubber, ethylene propylene rubber, epichlorohydrin rubber, nitrile butadiene rubber, and acrylic rubber. Molded ones can be used.

Further, as a developer regulating member used in the developing device in the image forming apparatus of this embodiment, a rebound resilience 1
Rubber or elastomer of 0% or more can be used.

In the toner T of this embodiment, the toner analysis is performed by the above-described analysis method. In the toner of this example, sprayed silica having a surface subjected to a hydrophobic treatment is used as an external additive. In toner analysis, measurement is performed using a particle analyzer.
In the particle analyzer, there are a total of four spectrometer channels each having a different blaze wavelength, so that when measurement is performed using different channels, the absolute value of the particle diameter is displayed with a deviation from the sensitivity difference of the spectrometer. Therefore, in the embodiment of the present invention, channels used for element detection are defined as follows in order to prevent the deviation of the absolute value of the particle diameter. Mother particles (C) of toner T: channel 1 or channel 2; external additives (SiO ₂ ): channel 3 or channel 4.

The particles of the toner T thus analyzed are
When the horizontal axis represents the toner particle diameter (equivalent particle diameter) and the vertical axis represents the number of the particle diameters, a normal distribution diagram of the toner particle diameter as shown in FIG. 4 is obtained.

Therefore, the toner T of the developer used in the embodiment of the developing device of the present invention has an average particle diameter of the entire toner (average particle diameter of the entire toner indicated by a chain line in FIG. 4).
3, that is, the asynchronous toner on the horizontal axis in FIG. 3, that is, the external additive (SiO ₂ ) 9 having less than a predetermined external additive concentration and the toner T particles adhering to the base particles (C) 8 and the external additive. Agent (Si
O ₂ ) 9 and the average particle size of the toner T composed of the base particles (C) 8 to which no toner is attached (the average particle size of the toner less than the predetermined external additive concentration indicated by the two-dot chain line in FIG. 4). And
Assuming that the average particle diameter of the entire toner is D1 and the average particle diameter of the toner composed of the base particles less than the predetermined external additive concentration is D2, the relationship of D1 / D2 <2 is satisfied.

As will be apparent from the above, according to the present invention, it is assumed that 0.1.
The external additive (SiO ₂ ) 9 has no external additive (SiO ₂ ) 9 and the toner T particles in which the external additive (SiO ₂ ) 9 having an equivalent particle diameter of 7 to 0.8 μm or less adheres to the base particles (C) 8. The toner in which toner particles composed of the non-base particles (C) 8 are combined, that is, the base particle asynchronous count toner is defined as a toner that does not satisfy a predetermined external additive concentration. Further, the sum of the synchronous count toner and the additive asynchronous count toner is defined as the entire toner.

In the toner T of this embodiment of the present invention thus configured, the toner T has an average particle diameter of the entire toner and an average particle diameter of the toner base particles (C) 8 which are less than a predetermined external additive concentration. By setting the ratio to the diameter to be 2 or more, the particle diameter of the toner T that does not satisfy the predetermined external additive concentration is substantially increased.

The reason why the particle size of the toner T that does not satisfy the predetermined external additive concentration becomes substantially larger is as follows.
Originally, the external additive (SiO ₂ ) 9 easily adheres to the small-sized toner base particles (C) 8 having a large specific surface area. However, the small-sized toner base particles (C) 8 Since the frequency of secondary aggregation is high, the external additive (SiO ₂ ) 9 is less likely to adhere to the small-sized toner mother particles (C) 8 which are secondary aggregated. Accordingly, the secondary aggregated toner mother particles (C) 8 having a small particle diameter tend to have a low coverage of the external additive (SiO ₂ ) 9 and cannot reach a sufficient external additive concentration. Actually, the large-diameter toner base particles (C) 8 existing as single particles are easily covered with the external additive (SiO ₂ ) 9. Therefore, in the conventional toner, the toner T having a concentration less than the predetermined external additive concentration tends to be biased toward the smaller diameter side. In the toner T of the present invention, conditions for performing the external addition process are set so that the secondary aggregated toner base particles (C) 8 having a small particle diameter are preferentially covered with the external additive (SiO ₂ ) 9. The shear strength is set so that the aggregated toner base particles having a small particle diameter are crushed. At this time, if the shear strength and the processing time are set unnecessarily large, the external additive (SiO ₂ ) 9 may be buried in the toner base particles (C) 8. The toner base particles (C) at the time of this external addition process
8 and the external additive (SiO ₂ ) 9 by optimizing the shear strength and the processing time, the external additive (SiO ₂ ) 9
Can be preferentially coated with an external additive without embedding the toner base particles (C) 8 in the toner base particles (C) 8. By externally adding the toner base particles in this manner, the particle size of the toner T that does not reach the predetermined external additive concentration is substantially increased.

Then, the toner T is applied to the developer regulating member 6.
At the contact portion between the toner carrier and the developer carrier 5 and in the vicinity thereof, the developer carrier is attached to the developer regulating member 6 by physical adhesion, and repeated between the developer regulating member 6 and the developer carrier 5 moving at high speed. Even if the toner T is subjected to thermomechanical stress due to rubbing, the toner T has a large heat capacity in accordance with its large particle size, so that the toner T is unlikely to undergo thermal deformation. Become. Therefore, the thermomechanical stress received from the outside is sufficiently dispersed to the surroundings, and the effect of suppressing the change in the shape of the toner itself can be obtained. As a result, the developer carrier 5 that moves at a high speed moves the developer regulating member 6 via the toner T.
, The phenomenon that the toner T is bonded to the adjacent toner particles or the surface of the developer regulating member 6 does not occur. This makes it difficult for the toner T to adhere to the developer regulating member 6, thereby preventing the toner T from being transported unevenly.

In the developing device 1, since the toner T is used as a developer, the toner T is less likely to adhere to the developer regulating member 6. Therefore, the durability of the developing device 1 is improved, and the developing device 1 can be repeatedly used for a long time only by replenishing the toner T.

In this way, in the toner T and the developing device 1 of this example, the unevenness of the transport of the toner T by the developer carrier 5 is eliminated, so that the image density unevenness in the form of a vertical stripe due to the unevenness of the transport is eliminated, and the image quality is reduced. Become good.

Incidentally, in the toner T of the present invention, the external addition treatment is performed so that the toner base particles (C) 8 having a small particle diameter secondary-aggregated are preferentially covered with the external additive (SiO ₂ ) 9. The application conditions are set to the shear strength at which the secondary aggregated toner base particles having a small particle diameter are crushed. Small particle size toner base particles (C)
In the case where the external additive (SiO ₂ ) 9 is coated with the external additive (SiO ₂ ) 9, the external additive (SiO ₂ ) 9 is too large since the shear strength is too large for the toner base particles (C) 8 having a large particle diameter. There is a problem that the toner is buried in the toner. To make up for this,
After the coating on the toner base particles (C) 8 having a small particle diameter is completed, the external additive (SiO ₂ ) 9 is re-charged, a small shear strength is set, and a relatively long time is spent for additional processing. ing.

In this case, it is preferable that the external additive 9 used in the external addition treatment has been subjected to a pulverization treatment in advance by a jet mill or the like. The material of the external additive 9 to be recharged may be a material other than silica (SiO ₂ ), which is the first external additive 9, and its particle diameter is different from that of the first external additive 9. The particle size may be used. Actually, an experiment was conducted on an example of the present invention.

[0046]

Example 1 In Example 1, the average particle diameter D1 of the entire toner
The ratio D1 / D2 of the average particle diameter D2 of the toner composed of the base particles having a concentration less than the predetermined external additive is 2.07, 1.92, 1.
Experiments were conducted on six types of toners, 72, 1.70, 1.67, and 1.45. Table 1 shows the results.

[0047]

[Table 1]

As is evident from the experimental results of Example 1 shown in Table 1, with the toner having a ratio D1 / D2 of 2.07, toner sticking occurs at 200 sheets where the number of printed sheets is considerably small, and this toner sticking occurs. As a result, image density unevenness occurred.
Further, for a toner having a ratio D1 / D2 of 1.92, 1000
Although a little toner sticking occurred on the sheet, due to the toner sticking, image density unevenness occurred to such an extent that the image quality was not substantially affected. Further, in the case of the toner having a ratio D1 / D2 of 1.72, a little toner fixation occurred at 10,000 sheets where the number of printed sheets was relatively large, but image density unevenness hardly occurred, and the image quality was not substantially affected. Furthermore, the ratio D1 / D
2 is 1.70 or less, the number of printed sheets is 10
Even when the number of sheets reached 000, little toner sticking occurred and there was no unevenness in image density. Therefore, the ratio D1 / D
When 2 is smaller than 2, it can be seen that the toner hardly adheres, and image density unevenness that substantially affects the image quality does not occur. In particular, the ratio D1 / D2 is 1.7
Below, good results were obtained in which no toner was fixed and no image density unevenness occurred. From this result, it is sufficient to set the ratio D1 / D2 to be smaller than 2, but it is more preferable to set the ratio to 1.7 or less.

In the above-described example, the toner analysis method disclosed in the above-mentioned collection of papers is used as a method for analyzing the adhesion state between the mother particles of the toner and the external additive. Needless to say, any toner analysis method can be used as long as it can obtain the average particle size of the equivalent particle size of the asynchronous toner and the average particle size of the equivalent particle size of the entire toner.

The developing device of the present invention is not limited to the developing device 1 shown in FIG. 5, but includes at least the developer carrier 5 and toner regulating means (including components other than the developer regulating member 6). The present invention can be applied to any developing device provided that it has a developing device.

Further, the present invention is not limited to silica fine particles as an external additive, but various materials can be used as described above. Therefore, when conducting an analysis test of the toner, the measurement can be similarly performed even when an external additive other than silica is used by appropriately selecting the emission spectrum of the element to be detected according to the material of the external additive. it can. In this case, for example, the emission spectrum of Ti may be detected and processed when titanium oxide is used as the external additive, and the emission spectrum of Al may be detected when alumina is used.

[0052]

As is apparent from the above description, according to the toner of the present invention, the average particle diameter of the entire toner and the average particle diameter of the toner composed of the base particles less than the predetermined external additive concentration are determined. Is set to be smaller than 2, it is possible to substantially increase the particle diameter of the toner that does not satisfy the predetermined external additive concentration. Thereby, even if the toner adhered to the toner regulating means by the physical adhesion is subjected to thermomechanical stress, the change in the shape of the toner can be suppressed.

Therefore, even if the developer carrier moving at a high speed is brought into contact with the toner regulating means via the toner, the phenomenon that this toner is bonded to the adjacent toner particles or the surface of the toner regulating means can be suppressed. Adhesion of the toner to the toner regulating means can be reduced, and uneven transport of the developer can be prevented.

Further, according to the developing device of the present invention, since the toner of claim 1 is used as the developer, the adhesion of the toner to the toner regulating means can be reduced, and the durability of the developing device can be improved. Therefore, the developing device can be repeatedly used for a long time only by replenishing the developer.

As described above, according to the toner and the developing device of the present invention, it is possible to eliminate the unevenness of the transport of the developer by the developer carrier, and also to prevent the occurrence of the image density unevenness in the form of a vertical stripe due to the unevenness of the transport. Good image quality can be obtained.

[Brief description of the drawings]

FIG. 1 shows an example of a conventional toner analysis method for use in analyzing the state of adhesion between a base particle of a toner, which is a developer, and an external additive used in an embodiment of a developing device according to the present invention. FIG.

FIG. 2 is a diagram illustrating equivalent particles and equivalent particle sizes used in the toner analysis method shown in FIG.

FIG. 3 is a diagram showing an analysis result by the toner analysis method shown in FIG. 1;

FIG. 4 is a normal distribution diagram showing a distribution of toner particle diameters based on the toner analysis result shown in FIG.

FIG. 5 is a diagram schematically illustrating a conventional one-component developing device including a developer carrier and a toner regulating blade.

FIG. 6 is a view for explaining toner fixation to a toner regulating blade and toner conveyance unevenness which occur when development is performed by the developing device shown in FIG. 5 using conventional toner particles.

FIG. 7 is a diagram showing toner particles having an external additive attached to mother particles.

DESCRIPTION OF REFERENCE NUMERALS 1: developing device, 2: toner container, 3: toner conveying means, 4: toner supply member, 5: developer carrier, 6: developer regulating member, 7: latent image carrier, 8 ... Base particles (C), 9 ...
External additive (SiO ₂ ), T ... toner

Claims (2)

[Claims] 1. A toner comprising a large number of base particles and a large number of external additives respectively attached to these base particles, wherein the average particle diameter of the whole toner is D1, and the base particles do not have a predetermined external additive concentration. Is defined as D2, the average particle diameter of the entire toner and the average particle diameter of the toner composed of the base particles having a concentration less than the predetermined external additive concentration satisfy the relationship of D1 / D2 <2. The toner is set as follows. 2. The image forming apparatus according to claim 1, further comprising: a developer carrying member for carrying the developer; and a toner regulating means for regulating the conveyance of the toner such that a uniform thin layer of the toner is formed on the developer carrying member. A developing device, wherein the toner according to 1 is used as a developer.