JP2537342B2 - Image forming method - Google Patents

Description

The present invention relates to a developing method for forming a brush of a small amount of magnetic particles on a toner holding member by using a dry developer and using the brush for development.

[Prior Art] Various methods have been proposed and put to practical use as dry development methods.

For example, in a developing method using a two-component developer, when the image portion of the latent image is developed by the developer applied on the developing roller, the toner in the developer is the toner applied on the developing roller. Use less than a few percent of This is extremely inefficient considering the developing device configuration. This is because it is necessary to apply a large amount of developer on the developing roller with a constant amount and a uniform toner concentration each time the developing roller rotates in order to obtain a predetermined sufficient developing concentration. Therefore, the size of the developing device is increased.
It was complicated. Of course, attempts have been made to improve the developing efficiency even in this type of developing method. For example, the present applicant has proposed JP-A-55-32060, 55-133058, 56-70560, and NP 8500
It has been put to practical use in copiers. According to this, although the development density can be increased and the development efficiency can be increased, the development efficiency close to 100% cannot be achieved in the image area, and this type of development method still has room for improvement. Is left.

In terms of improving development efficiency, the one-component development method is two
Better than the component development method. Among them, in Japanese Patent Application Laid-Open No. 54-43037, which was previously filed by the applicant of the present invention, a toner thin layer of 200 μm or less is formed on the developing roller, and the toner applied on the sleeve is developed to almost 100% in the image area. Developing with efficiency. Therefore, it was possible to put the developing device into a compact and simple structure for practical use. This was achieved because a thin layer of 200 μm or less could be formed on the developing roller. However, it is extremely difficult to form a thin layer of a dry developer in either one-component development or two-component development. Therefore, even in the one-component development, a relatively thick layer is formed by anyone other than the applicant. Configure the device. From the viewpoint of image quality, at the present time, it is required to improve the sharpness and resolution of a developed image, and development of a thin layer forming method of a dry developer and its apparatus is indispensable.

By the way, the above-mentioned applicant's method relates to the formation of a thin layer of the magnetic toner. In order to give the magnetic toner magnetism, it is necessary to internally add a magnetic substance to the toner. This is because of poor fixability when thermally fixing a developed image transferred onto a transfer paper, and the magnetic substance is internally added to the toner itself. Therefore (the magnetic substance is usually black), there is a problem such as poor color when reproducing the color.

Therefore, as a method for forming a thin layer of non-magnetic toner, a soft brush such as beaver hair is made into a cylindrical brush, and toner is adhered and applied to the brush, or a developing roller whose surface is made of fiber such as velvet. There has been proposed a method of coating with a doctor blade or the like.

However, when an elastic blade is used as a doctor blade for the fiber brush, the amount of toner can be regulated, but uniform application is not performed, and the fiber of the brush is simply rubbed by rubbing the fiber brush on the developing roller. Since triboelectrification charges are not applied to the toner existing between them, there is a problem that fogging or the like is likely to occur.

Further, magnetic toners can easily prevent toner scattering by utilizing magnetic force, but non-magnetic toners cannot utilize magnetic force and toners are easily scattered inside the machine. The inconveniences described above occur not only during copying but also when vibration or shock is applied during transportation of the apparatus.

The applicant of the present invention uses a non-magnetic toner and magnetic particles as a developing device which is completely different from the above-mentioned conventional method, provides a magnetic particle restraining member facing the toner carrying member, and restrains the magnetic particle with respect to the moving direction of the surface of the holding member. A method has already been proposed in which a magnetic brush of magnetic particles is formed upstream of the member by the magnetic force of the magnetic field generating means, the magnetic brush is restricted by the magnetic particle restriction member, and a thin layer of non-magnetic toner is formed on the toner holding member. (JP-A-58-143360). According to this method, the gap between the latent image carrier and the toner carrier in the developing section is set wider than the toner layer thickness, and an alternating electric field is applied to obtain a non-magnetic toner developed image on the surface of the latent image carrier. It was put to practical use. As a result, it is possible to obtain a color developed image with a small and simple developing device configuration that has extremely high developing efficiency. Especially in two-component magnetic brush rubbing development,
A good quality solid image was obtained without rubbing marks generated in the solid image portion. However, there has been a demand for further improvement in development image quality, for example, development of a development system that further improves gradation.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned conventional circumstances, and it is a development method capable of obtaining a developed image which has extremely high development efficiency and is not inferior to the conventional development method. For the purpose of provision.

In particular, a main object of the present invention is to provide a simple image forming method for forming a stable image even under special conditions such as high temperature and high humidity and low temperature and low humidity.

[Means and Actions for Solving Problems] Specifically, according to the present invention, a latent image holding member for holding a latent image and a developer carrying member facing the latent image holding member are provided. In the formed developing area, the latent image is formed by a two-component developer containing a non-magnetic toner and magnetic particles while applying an alternating electric field between the developer carrying body containing a magnet inside and the latent image holding body. In an image forming method of developing with a formed magnetic brush, the amount of magnetic particles conveyed to a developing area is regulated and the magnetic particles are circulated in a developer supply container, and a two-component system on the developer carrier is provided. Between the compound A, which conveys the developer to the developing area and is located in the opposite direction to the non-magnetic toner with respect to the surface of the developer carrier in the triboelectric charging series, and the compound A and the non-magnetic toner in the triboelectric series. Is treated with Compound B located at The amount of magnetic particles present in the developing area of the developer carrier is 5 to 100 mg / cm.
^A magnetic brush is formed so as to have a particle diameter of 2, and 0.01 to 5 parts by weight of fine particles of compound C, which are located in the opposite direction to the surface of the developer carrier in the triboelectrification series, per 100 parts by weight of the non-magnetic toner. A non-magnetic toner image of which part is externally added and mixed is reciprocated between the surface of the developer carrying member and the surface of the magnetic brush and the latent image holding member in the developing area to form a non-magnetic toner image on the latent image holding member. The present invention relates to an image forming method.

The non-magnetic toner referred to here is an external magnetic field 5000e,
A toner that exhibits a magnetization of 10 emμ / g or less and cannot substantially behave as a magnetic toner. The term "developing area" as used herein refers to an area of about 10 mm centering on the closest position between the latent image carrier and the developer carrier in the developer carrier.

The inventors of the present invention proposed the above-mentioned Japanese Patent Application Laid-Open No. 58-143360 and, as a result of diligent research on its improvement, as a result, a clear developing magnetic pole was formed in the developing section to perform locally concentrated development. In the one-component developing method, the triboelectric charge is imparted to the toner mainly between the surface of the sleeve and the surface area of the sleeve is substantially increased, whereby the triboelectricity of the toner is stabilized and the sleeve is stabilized. It has been found that stabilization of the toner supply to the top and improvement of image quality such as gradation and uniformity are achieved. Further, the combination of the magnetic particles and the non-magnetic toner used in the present invention is good even when applied to the present development method, even against environmental changes, particularly changes to special environments such as high temperature and high humidity and low temperature and low humidity. We found that it produces the effect of providing stable images.

Although the detailed mechanism has not been completely clarified yet, it is generally estimated as follows from the experimental facts so far.

That is, since the compound A has a charging characteristic opposite to that of the toner during the treatment of the magnetic particles, it has a role of imparting the original charging to the toner, and the compound B controls the excessive charging of the toner and the magnetic particles. However, it is considered that the mold releasing effect is exhibited to some extent. Therefore, by appropriately controlling the treatment amount ratio of the compounds A and B to the magnetic particles, it is possible to control the balance between the adhesion and the releasability of the toner and the magnetic particles. However, under special conditions such as changes in environmental conditions, especially high temperature and high humidity, low temperature and low humidity, the chargeability between the toner and the magnetic particles changes subtly, which causes some problems such as a slight change in image reflection density and an increase in fog. May occur. To prevent this, it is best to change the treatment amount ratio of the compounds A and B to the magnetic particles according to each environment, but it is impossible in reality. Therefore, when the compound C, which acts in the same manner as the compound A in terms of charge, is held as fine particles in the toner,
Since the fine particles of the compound slightly separate from the toner in one environment and substantially serve to enhance the charging of the toner similarly to the compound A as the magnetic particle treating agent, and in another environment, they adhere to the toner base. In addition, the toner does not participate in the charging property of the toner, and it is considered that the toner is present between the toner base and the magnetic particles and serves as an appropriate charge control agent.

Hereinafter, the main developing method will be described with reference to Examples. First
The figure is an embodiment according to the present invention. In FIG.
3 is a latent image holding member, 21 is a toner supply container, 22 is a non-magnetic sleeve, 23 is a fixed magnet, 24 is a non-magnetic blade, 26 is a magnetic particle circulation region limiting member, 27 is magnetic particles, 28 is non-magnetic toner, Reference numeral 29 is a developer collecting container portion, 30 is a scattering prevention member, 31 is a magnetic member, 32 is a developing region, and 34 is a bias power source. The sleeve 22 rotates in the b direction, and the magnetic particles 27 circulate in the c direction accordingly. This causes contact and rubbing between the sleeve surface and the magnetic particle layer to form a non-magnetic toner layer on the sleeve surface. Further, while the magnetic particles circulate in the c direction, a part of the magnetic particles is regulated to a predetermined amount by the gap between the nonmagnetic blade 24 and the sleeve 22, and is applied onto the nonmagnetic toner layer. That is, the non-magnetic toner is applied on both the surface of the sleeve and the surface of the magnetic particles, and the effect equivalent to that of substantially increasing the surface area of the sleeve is exhibited.

In the developing area 32, one of the magnetic poles of the fixed magnet 23 is opposed to the latent image surface to form a clear developing pole, and the alternating electric field causes the toner to fly and develop on the sleeve and from the magnetic particles. (This phenomenon will be described later.)
After development, the magnetic particles and the undeveloped toner are collected in the developing container as the sleeve rotates.

The sleeve 22 may be a paper cylinder or a synthetic resin cylinder, but can be used as a developing electrode roller if the surface of these cylinders is subjected to a conductive treatment or is made of a conductor such as aluminum, brass or stainless steel.

The coating amount of the magnetic particles on the downstream sleeve surface of the non-magnetic blade 24 in the present invention is 5 to 100 mg / cm ² , preferably 10 to 80 mg / in order to sufficiently utilize both the magnetic brush and the surface of the sleeve 22. A small amount of about cm ² is desirable. If the amount of magnetic particles present on the surface of the sleeve is too large, the regulation force by the non-magnetic blade 24 is weakened, the sliding force between the sleeve and the magnetic particles is reduced, and the toner can be smoothly charged. Can not. Further, the magnetic particles also fly during the flight development of the toner, and the latent image carrier 3
There is a drawback that it adheres to the top. On the contrary, if the amount of the magnetic particles existing on the sleeve surface in the developing area 32 is too small, the amount of toner applied to the developing area is reduced, resulting in uneven density and reduced image density. The amount of magnetic particles present on the surface of the sleeve mainly depends on the gap between the sleeve 22 and N of the fixed magnet 23.
_It can be adjusted by the position of the ₁ pole, the magnetic density of the S ₁ pole, and the like.

The method for measuring the abundance of magnetic particles in the present invention is described below. First, a magnetic brush made of only magnetic particles was formed on the sleeve, magnetic particles in a portion corresponding to the developing area were sucked using a cylindrical filter as a filter, and the weight M (mg) was measured. Next, the remaining magnetic particles on the sleeve after the magnetic particles were attracted were sampled with a transparent adhesive tape, and the occupied area S (cm ² ) of the attracted magnetic particles was determined. The abundance m (mg / cm ² ) of magnetic particles was calculated as follows.

The gap d between the tip of the non-magnetic blade 24 and the surface of the developing sleeve 22 at the position of m = M / S point 25 is 50 to 700 μm, preferably 100 to 600 μm. If the distance d is less than 50 μm, magnetic particles, which will be described later, will be clogged, and the sleeve will be damaged. On the other hand, if it is larger than 700 μm, a large amount of non-magnetic toner and magnetic particles, which will be described later, leak out and a thin layer cannot be formed.

In FIG. 1, reference numeral 26 is a magnetic particle circulation region limiting member whose lower surface is in contact with the upper surface side of the non-magnetic blade 24 and whose front end surface is an undercut surface.

Denoted at 27 and 28 are magnetic particles and non-magnetic toner that are sequentially accommodated in the toner supply container 21.

The bottom plate of the toner supply container 21 is extended below the developing sleeve 22, which is a toner holding member, to prevent the toner from leaking to the outside. In order to further prevent the leakage of this toner to the outside, a leakage toner collection container portion 29 that receives and restrains the leakage toner and a scattering toner along the length of the tip edge of the extension bottom plate are provided on the upper surface of the extension bottom plate. Prevention member
30 is provided. A voltage described later is applied to this member 30.

The magnetic particles 27 generally have an average particle size of 30 to 100 μm, preferably 40 to 80 μm. Each magnetic particle may be composed of only a magnetic material, a combination of a magnetic material and a non-magnetic material, or a mixture of two or more kinds of magnetic particles. Then, by first inserting the magnetic particles 27 into the toner supply container 21, the magnetic particles 27 from the toner supply container 21 in which the magnetic particles 27 face the inside of the container 21, that is, the sleeve 22 are arranged. Alternatively, the magnetic particle layer in the sleeve 22 is attracted and held by each magnetic field by the magnet 23 in the sleeve 22 in each part of the sleeve surface area from the magnetic member 31 for preventing the leakage of the toner to the tip of the non-magnetic blade 24 which is the magnetic particle restraining member. The entire surface area is covered. The non-magnetic toner 28 is stored in the container 21 after the magnetic amount particles 27 are charged.
The first with respect to the sleeve 22 by being put into
A large amount of it is stored outside the magnetic particle layer as a layer and exists as a second layer.

It is preferable that the magnetic particles 27 to be initially charged contain about 2 to 70% (weight) of the non-magnetic toner 28 based on the magnetic particles, but the magnetic particles may be magnetic particles only. Further, once the magnetic particles 27 are sucked and held as a magnetic particle layer in the sleeve surface area, they do not substantially flow toward the sleeve surface area due to vibration of the apparatus or even if the apparatus is tilted to a considerably large extent. The overall covered state is retained.

Thus, in the state where the magnetic particles 27 and the non-magnetic toner 28 are sequentially charged and accommodated in the container 21 as described above, the magnetic particle layer portion near the sleeve surface corresponding to the magnetic pole S ₂ position of the magnet 23 is A magnetic brush of magnetic particles is formed by a magnetic field having a strong magnetic pole.

Further, the magnetic particle layer portion near the tip of the non-magnetic blade 24, which is a magnetic particle regulating member, is regulated based on the effect of gravity and magnetic force and the presence of the non-magnetic blade 24 even if the sleeve 22 is driven to rotate in the direction of arrow b. Due to the balance between the force and the conveying force of the sleeve 22 in the moving direction, the force accumulates at a point 25 on the surface of the sleeve 22 and forms a stationary layer which can move a little but dwell.

When the sleeve 22 is rotated in the direction of the arrow b, the magnetic brush can be moved near the magnetic pole S ₂ by appropriately selecting the position of the magnetic pole and the fluidity and magnetic characteristics of the magnetic particles 27.
Circulating in the direction to form a circulating layer. In the circulation layer,
The magnetic particles that are relatively close to the sleeve 22 rise up from the vicinity of the magnetic pole S ₂ onto the stationary layer on the downstream side of the rotation of the sleeve by the rotation of the sleeve 22. That is, it receives the force of pushing it up. The magnetic particles pushed up are provided with a magnetic particle circulation region limiting member 26 provided on the non-magnetic blade 24.
Therefore, since the upper limit of the circulation area is determined, it does not ride on the non-magnetic blade 24, falls by gravity, and returns to the vicinity of the magnetic pole S ₂ again. In this case, the magnetic particles having a small push-up force, which are received far away from the sleeve surface, may drop before reaching the magnetic particle circulation region limiting member 26. That is, in the circulation layer, the magnetic brush circulates the magnetic particles as indicated by the arrow c due to the magnetic force and the frictional force due to the gravity and the magnetic poles and the fluidity (viscosity) of the magnetic particles. The non-magnetic toner 28 is successively taken in from the toner layer on the upper side and returned to the lower part in the developer supply container 21, and this circulation is repeated as the sleeve 22 is driven to rotate.

As the developing bias voltage 34, an alternating voltage having the same peak voltage on the positive side and the negative side, or a DC voltage superimposed on the alternating voltage can be used. For example, with respect to an electrostatic latent image having a dark portion latent image potential of −600 V and a bright portion latent image potential of −200 V, as an example, a DC voltage −300 V is superimposed on the sleeve 22 and a peak voltage V _{pp of} 300 to 2000 V and a frequency 200 An alternating voltage selected in the range of up to 3000 Hz is applied to hold the photosensitive drum 3 at the installation potential. Generally, the electric resistance of the magnetic brush is relatively high (greater than 10 ⁸ Ωcm), in which case the peak voltage width V _pp of the developing bias should be high (for example, 800 V or higher) and the frequency is 600 Hz or higher, preferably 800 Hz or higher. Preferably 1kHz
As described above, the higher the quality, the better the image quality with sufficient density. However, even if only V _pp is high, if the frequency is low, the density is low and it is difficult to obtain good image quality. In any case, the upper limit of V _pp is determined by the gap discharge limit value of the developing section, and the lower limit thereof is determined by the toner flight limit value on the sleeve and the magnetic particles.

Taking the above into consideration, the resistance of the entire developing magnetic brush is preferably 10 ⁸ Ωcm or more in the thickness direction of the developing brush when the latent image carrier 1 is in contact with the developing brush.

Incidentally, the resistance value of the magnetic particles and the magnetic brush described in the present invention means the developing sleeve 22 by the developing device shown in FIG.
A magnetic brush of 50 mg / cm ² magnetic particles is formed on the top, a developing sleeve and a conductive metal drum with a gap of about 300 μm are provided opposite to this, and a circuit with a resistance of about 1 MΩ connected in series with them. It is calculated and calculated from the value of the current that flows when a DC voltage of 200 V is applied.

The phenomenon in the developing section 32 will be described below regarding the developing method according to the present invention.

2 and 3 are enlarged explanatory views of the developing section in the developing method according to the present invention. 50 is the latent image charge in the dark area on the latent image carrier. 28 is a non-magnetic toner. 34 is an alternating voltage power supply on which a DC component is superimposed. 2 shows the case where a plus waveform component of the alternating voltage is added to the sleeve 22, and FIG. 3 shows the case where a minus waveform component of the alternating voltage is added. The polarity of the latent image charge is shown as negative and the polarity of the developer is shown as positive.

Since the resistance of the developing brush 51 is relatively large (greater than about 10 ⁸ Ωcm), the developing brush 51 depends on the charging / discharging time constant of the charge due to the material of the developing brush 51 itself and the like. Alternatively, there is a charge injected by the mirror charge, the latent image electric field on the latent image carrier 3 and the alternating electric field between the latent image carrier 3 and the sleeve 22.

When the electric field due to the latent image charge 50 in the dark portion on the latent image carrier 3 and the electric field due to the alternating electric field coincide with each other, the developing brush 51 is in the maximum sagging state in the sleeve 22 direction.

When the direction of the electric field due to the latent image charge on the latent image carrier 3 and the direction of the electric field due to the alternating electric field do not match, the yielding of the developing brush 51 becomes small.

In any case, as described above, the developing brush is generated by the alternating electric field.
51 is in a fine but violent vibration state, and the fog toner excessively attached to the latent image holding member is rubbed by the developing brush, removed from the latent image holding member 3, and pulled back onto the brush. Further, due to the vibration of the brush, the toner is easily separated from the brush 51 and is easily supplied to the latent image holding member 3, so that the image density is also improved. Also brush 51
The above-mentioned vibration loosens the toner in the brush 51, which contributes to improvement of image density and prevention of ghost. further,
When this vibrating state is severe, a part of the magnetic brush separates from the brush or the sleeve and reciprocates between the latent image carrier and the sleeve surface. The kinetic energy of this reciprocating brush is large and efficient, and the effect of the above-mentioned vibration is expected. The above behavior of the magnetic particles in the developing section is a phenomenon observed as a result of high-speed photography of 8000 frames per second with a high-speed camera.

The toner coating magnetic particles used in the present invention include:
For example, surface-oxidized or non-oxidized metals such as iron, nickel, cobalt, manganese, chromium, rare earths, and alloys or oxides thereof can be used. Further, there is no particular limitation as a manufacturing method thereof.

The compounds A, B, and C differ depending on the material of the surface of the toner holding member and the toner material. For example, when a metal such as aluminum or stainless steel is used as the toner holding member and the toner is positively charged, the compound A
Alternatively, C is polytetrafluoroethylene / monochlorotrifluoroethylene polymer / polyvinylidene fluoride / silicone resin / polyester resin / ditertiary butylsalicylic acid metal complex, and the compound B is styrene resin / acrylic resin / polyacid / silicone. If there is a resin, polyvinyl butyral, etc., and the toner is negatively charged, the compound A or C is nigrosine, amino acrylate resin, acrylic resin, basic dye and its lake, and the compound B is styrene resin, silicone. It is suitable to use a resin / polyester resin, but it is not necessarily limited thereto.

Further, the positions of the compounds A and C on the triboelectric series are preferably close to each other, and it is sufficiently possible that the compounds have substantially the same chemical structural formula.

The total amount of the compounds A and B treated is 0.1 to 30% by weight (preferably 0.5 to 20% by weight) based on the magnetic particles of the present invention.
Weight percent), the ratio of compounds A and B is 10: 9 by weight.
0 to 99: 1 (preferably 20:80 to 90:10, particularly preferably 30:70
~ 80: 20) is desirable.

Further, as the treatment method with the compounds A and B, a conventional carrier such as a method of mixing with powder and melting or softening with heat to adhere to magnetic particles, a method of dissolving or suspending in a solvent and coating and adhering to magnetic particles, etc. Any known method for particles can be applied.

Next, a method of measuring the triboelectric charge amount in the present invention will be described.
The toner and the surface-treating substance for the magnetic particles were pulverized and classified so that they could be regarded as having substantially the same particle size. As for the grain size,
Number average 9 to 11μ measured by Coulter counter
m, volume average 13 to 15 μm, 6.35 μm or less Number distribution 20% or less,
The volume distribution was set to 20.2 μm or more and 15% or less.

FIG. 4 is an explanatory diagram of the triboelectric charge amount measuring device. 40 at the bottom
A toner for measuring the triboelectric charge amount in a metal measuring container 12 having a conductive screen 13 of 0 mesh (which can be appropriately changed to a size through which magnetic particles do not pass), or a substance for surface treatment of the magnetic particles, The weight ratio of amorphous iron powder with a particle size between ~ 300 mesh (EFV200 / 300 made by Nippon Iron Powder, the surface is untreated and has virtually no triboelectricity of its own like the toner carrier) is 1: 9. Metal lid 14 containing about 4g of mixture (developer)
do. At this time, weigh the entire measuring container 2 and W
₁ (g). Next, in the suction device 11 (at least the portion in contact with the measurement container 2 is an insulator), suction is performed from the suction port 17 and the air volume control valve 16 is adjusted to set the pressure of the vacuum gauge 15 to 70 mmHg. In this state, suction is sufficiently performed (for about 1 minute) to remove the toner or the surface treatment substance of the magnetic particles by suction. The potential of the electrometer 19 at this time is V (volt). Here, 18 is a capacitor, and the capacity is C (μF). The weight of the entire measuring container after suction is weighed and is W ₂ (g). This triboelectric charge amount T (μC / g) is calculated by the following equation.

However, the measurement conditions are 23 ° C and 50% RH.

On the other hand, in order to retain the compound C in the toner, it is desirable that the average particle diameter thereof be 5 μm or less, more preferably 1 μm or less. Further, the fine particles of the compound C are preferably kept in an amount of 0.01 to 5 parts by weight, more preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the non-magnetic toner.

If the compound C is not added in the form of fine particles and added to the toner as described above, the object of the present invention may not be sufficiently achieved.

On the other hand, as the binder resin for the toner used in the present invention, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene and the like, or a substituted polymer thereof;
Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-
Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Coalesce, styrene-butyl methacrylate copolymer,
Styrene-acryl-aminoacrylic copolymer, styrene-aminoacrylic copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid Styrene copolymers such as ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral , Polyacrylic acid resins, rosin-modified rosin, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffin, and paraffin wax may be used alone or in combination.

In the toner, any suitable pigment or dye can be used as a colorant. For example, there are known facial cleansers such as carbon black, iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

Further, as a charge control agent, an amino compound, a quaternary ammonium compound and an organic dye, particularly a basic dye and a salt thereof, benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride,
Nigrosine base, nigrosine hydrochloride, safranine γ and crystal violet, metal-containing dyes, salicylic acid-containing metal compounds and the like may be added. Further, magnetic powder may be added to the extent that the effects of the present invention are not impaired.

The above toner composition may be used for a toner by a commonly used mixing-pulverizing method, or may be used for a wall material or a core material of a microcapsule toner or both.

EXAMPLES The present invention will be described in more detail with reference to examples.

The developing device shown in FIG. 1 was used. In the apparatus of the embodiment, the photosensitive drum 3 is 60 mm / in the direction of arrow a.
Rotates at a peripheral speed of seconds. 22 is a stainless steel with an outer diameter of 32 mm and a thickness of 0.8 mm that rotates at a peripheral speed of 66 mm / sec in the direction of arrow b (SUS
304) sleeve, the surface of which was subjected to irregular sand plast using # 600 alundum abrasive grains so that the roughness of the circumferential surface was 0.8 μm (R _Z =).

On the other hand, a ferrite sintered type magnet 23 is fixedly arranged in the rotating sleeve 22, and the magnetic pole arrangement is such that the maximum value of the surface magnetic flux density is about 800 gauss as shown in FIG. The non-magnetic blade 24 was made of non-magnetic stainless steel having a thickness of 1.2 mm so that the amount of magnetic particles present on the sleeve was 30 to 60 mg / cm ^2, and the blade-sleeve gap was 300 μm.

On the surface of the photosensitive drum 3 facing the sleeve 22,
As an electrostatic latent image, a charge pattern of -150 V in the dark part and -150 V in the light part was formed, and the distance from the sleeve surface was set to 300 μm. Then, a frequency of 800 Hz is generated by the power source 34 with respect to the sleeve,
Development was carried out by applying a voltage having a peak-to-peak value of 1.4 KV and a center value of -300V.

Example 1 100 parts by weight of styrene-2 ethylhexyl acrylate-diethylaminoethyl methacrylate copolymer (80: 17: 3) Rhodamine-based pigment 5 parts by weight Red fine powder having an average particle diameter of 13 μm 100 parts by weight was positively charged with colloidal 1.0 part by weight of silica was added to obtain a toner. The triboelectric charge amount of the toner was +23.5 (μC / g).

Next, 100 parts of ferrite particles having a particle size of 50 to 70 μm as magnetic particles were added to 0.5 parts by weight of styrene-methylmethacrylate copolymer (30:70) (amount of triboelectrification +3.8 μC / g) 0.5 parts by weight of polyvinylidene fluoride (〃 -15.2 μC / g) was dipped in a xylene solution in which it was dispersed and dissolved, and heated and dried with stirring to prepare.

Further, 12 parts by weight of 100 parts by weight of the toner and 0.5 parts by weight of the fine particles of polyvinylidene fluoride (particle size 1 μm or less) were mixed with 100 parts by weight of the magnetic particles, and the mixture was applied to the developing device of FIG. When an image is output, a clear image with good gradation and no gradation is obtained, and the image reflection density is
It was 1.28. Further, when the durability of the developer was examined to obtain 10,000 sheets, a clear image without fog (image density 1.26) was obtained as in the initial stage. On the other hand, when images were similarly printed in a high temperature and high humidity environment (30 ° C., 90% RH), the image density was 1.25, and an image free from problems such as fog was obtained. Also, low temperature and low humidity environment (10 ℃, 10%)
Even below, a clear and fog-free image with an image density of 1.24 was obtained.

Comparative Example A multi-sheet durability test was conducted in the same manner as in Example 1 except that the fine particles of polyvinylidene fluoride used as the compound C were not added to the developer. At the beginning of image creation,
A clear image with an image density of 1.26 was obtained, but fog was developed in the non-image area from about 7,000 sheets, and the image density was also reduced to 1.18.

Example 2 Same as Example 1 except that the coating resin for magnetic particles was 0.5 parts by weight of polymethylmethacrylate (triboelectric charge amount +6.2 μC / g) and 0.5 parts by weight of polytetrafluoroethylene (〃-12.1 μC / g). The same good result was obtained.

Example 3 100 parts by weight of polyester resin 0.5 parts by weight of colloidal silica was added to 100 parts by weight of blue particles having an average particle diameter of 11 μm, which was made up of 3 parts by weight of phthalocyanine pigment, to prepare a toner. The triboelectric charge was −27.3 μC / g.

In addition, styrene-dimethylaminoethyl acrylate copolymer (97: 3) 0.5 parts by weight (friction charge +35.6 μC / g) Styrene-butyl methacrylate copolymer (80:20) 1.0 parts by weight (〃 −1.1 μC / g g) was coated on the surface of ferrite particles in the same manner as in Example 1 to obtain magnetic particles.

8 parts by weight of a mixture of 100 parts by weight of the toner and 0.3 part by weight of the styrene-dimethylaminoethyl acrylate copolymer fine particles (particle size: 1.5 μm or less) and magnetic particles 100
By mixing with parts by weight and applying it to the developing device of FIG. 1, towards the electrostatic latent image of dark part + 600V, bright part + 150V on the surface of photoconductor drum 3, frequency 800Hz, peak-to-peak value 1.4KV, center value +30
When a voltage of 0 V was applied and development was performed, the same good results as in Example 1 were obtained.

[Effects of the Invention] As described above, according to the present invention, in a developing device using magnetic particles with a simple structure, by interposing a small amount of magnetic particles in the developing area, there is no background fog and good gradation is obtained. In addition, good image quality without negative characteristics could be obtained in various environments.

Further, by effectively distributing the toner that contributes to the development on the sleeve and the magnetic particles and performing the flight development from both of them, it was possible to achieve a development efficiency of nearly 100% in an alternating electric field. This is a compact developing device configuration.
This enables simplification.

Further, the brush of magnetic particles according to the present invention was brought into contact with the latent image carrier and vibrated by at least an alternating electric field, whereby the ground fog toner adhering to the latent image carrier could be removed.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a developing device according to the developing method according to the present invention, FIGS. 2 and 3 are enlarged explanatory views of a developing portion by the developing method according to the present invention, and FIG. 4 is an explanation of a triboelectric charge measuring device. It is a figure. 3 ... latent image holding member, 11 ... suction device, 12 ... measuring container,
13 …… conductive screen, 14 …… metal lid, 15 ……
Vacuum gauge, 16 ... Air flow control valve, 17 ... Suction port, 18 ... Condenser, 19 ... Electrometer, 21 ... Developer supply container, 22 ...
… Non-magnetic sleeve, 23 …… Fixed magnet, 24 …… Non-magnetic blade, 26 …… Magnetic particle circulation region limiting member, 27 …… Magnetic particles, 28 …… Non-magnetic toner, 29 …… Developer collection container , 30
...... Scatterproof member, 31 ...... Magnetic member, 32 ...... Development area,
34 ... Bias power supply, 50 ... Electrostatic latent image, 51 ... Magnetic brush.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 15/09 G03G 13/08

Claims (1)

(57) [Claims] 1. A developer carrying device having a magnet inside in a developing region formed between a latent image carrying member for holding a latent image and a developer carrying member facing the latent image carrying member. In an image forming method, a latent image is developed with a magnetic brush formed of a two-component developer containing a non-magnetic toner and magnetic particles while applying an alternating electric field between the body and the latent image carrier. The amount of magnetic particles conveyed to the developer is controlled and the magnetic particles are circulated in the developer supply container, the two-component developer on the developer carrier is conveyed to the developing area, and the developer is carried in the triboelectric charging series. A developer using magnetic particles treated with a compound A located in the direction opposite to the non-magnetic toner with respect to the body surface and a compound B located between the compound A and the non-magnetic toner on the triboelectric series. The presence of magnetic particles in the development area of the carrier. The amount is 5~100mg / cm ²
A magnetic brush is formed so that the amount of fine particles of Compound C is 0.01 to 5 parts by weight per 100 parts by weight of the non-magnetic toner, which is located in the opposite direction to the surface of the developer carrier in the triboelectric charging series. Forms a non-magnetic toner image on the latent image holding member while reciprocating the non-magnetic toner mixed with the external additive in the developing region between the surface of the developer carrying member and the surface of the magnetic brush and the latent image holding member. An image forming method characterized by the above.