JPH0820746B2 - Dry developer and image forming method using the developer - Google Patents

Description

The present invention relates to a novel developer used for electrophotography, electrostatic recording, magnetic recording and the like, and an image forming method using the developer.

[Prior Art] In electrophotography, an electrostatic latent image is first formed by utilizing the properties of a photoconductor such as cadmium sulfide, polyvinylcarbazole, selenium, and zinc oxide. For example, in general,
A charge is uniformly applied on the photoconductor layer and imagewise exposed to form an electrostatic latent image. Then, it is developed with a toner powder charged in the opposite polarity to the charge of the electrostatic latent image, and further transferred and fixed on a transfer sheet if necessary.

On the other hand, in the case of an apparatus having a transfer step, it is usual to remove the residual toner on the latent image carrier that has not been transferred to the transfer sheet, and repeatedly use the latent image carrier.

As a method for removing the residual toner on the latent image holding member, a blade cleaning method, a fur brush cleaning method, a magnetic brush cleaning method or the like is generally performed by bringing a cleaning member into contact with the latent image holding member. In this case, since the cleaning member is pressed against the latent image holding member with an appropriate pressure, the latent image holding member may be scratched or the toner may be fixed during repeated use. In order to avoid the phenomenon that the toner adheres to the latent image carrier, it is proposed in JP-A-48-47345 to add both a friction-reducing substance and an abrasive substance to the toner. This method is effective in avoiding the toner sticking phenomenon, but has the following drawbacks. That is,
When the friction reducing substance is added to the extent that the toner sticking phenomenon can be avoided, it becomes difficult to remove low electric resistance substances such as paper powder and ozone adducts that are generated or adhered to the surface of the latent image holding member by repeated use, Particularly, in a high temperature and high humidity environment, the latent image on the latent image carrier is significantly impaired by the low electric resistance.

In addition, the amount of each of the friction reducing substance and the polishing substance added is delicate, and if the amount of the polishing substance sufficient to remove the deposits on the photosensitive member is added, it may damage the latent image holding member or the cleaning blade. There is a phenomenon that damages cause cleaning failure.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above problems in an image forming method using a dry developer including at least magnetic particles and a non-magnetic toner.

That is, an object of the present invention is to provide a developer and an image forming method which are excellent in cleaning characteristics without filming or cleaning failure of the latent image carrier.

Another object of the present invention is to provide a developer and an image forming method capable of obtaining an excellent image of high density from the initial stage.

It is another object of the present invention to provide a developer and an image forming method which are free from fogging due to durability, sleeve contamination, and image deterioration.

[Means and Actions for Solving Problems] The present inventors have completed the present invention as a result of earnest researches for overcoming the above-mentioned problems in the prior art and achieving the above-mentioned object. It was

That is, in the present invention, a latent image is formed by applying an alternating electric field between the developer carrying member and the latent image holding member in the developing area of the developer carrying member facing the latent image holding member for holding the latent image. In a developer comprising at least a non-magnetic toner and magnetic particles used in an image forming method of developing with a non-magnetic toner, the magnetic particles have a direction opposite to that of the non-magnetic toner with respect to the surface of the developer carrier in the triboelectric charging series. Compound A located at
And the compound B located between the compound A and the non-magnetic toner in the triboelectric series, the volume average particle size of the magnetic particles is 35 to 65 μm, and the volume particle size distribution shows a particle size. It is a dry developer characterized by having a particle size of less than 35 μm in an amount of 5 to 25% by weight and having a particle size of 35 to 40 μm smaller than that having a particle size of less than 35 μm.

Further, in the developing area of the developer carrying member facing the latent image holding member for holding the latent image, the latent image is applied to the non-magnetic toner while applying an alternating electric field between the developer carrying member and the latent image holding member. In the image forming method, the compound A is located in the direction opposite to the non-magnetic toner with respect to the surface of the developer carrying member in the triboelectric charging series, and between the compound A and the non-magnetic toner in the triboelectric series. Having a volume average particle size of 35 to 65 μm, a volume particle size distribution of less than 35 μm in an amount of 5 to 25% by weight, and a particle size of 35 to 40 μm With less than 35 μm particle size, a magnetic brush is formed in the developing area of the developer carrying member so that the existing amount of the magnetic particles is 5 to 80 mg / cm ^2, and a latent image is formed in the developing area. Formed on the surface of the carrier and the developer carrier, and on the surface of the developer carrier. The step of reversal developing the latent image while reciprocating the non-magnetic toner with the surface of the magnetic brush, the step of transferring the image on the latent image carrier to the transfer member, and the residual development on the latent image carrier. An image forming method characterized by comprising a step of removing the agent.

In general, if toner adheres to the latent image holding member, cleaning failure or the like occurs, which causes deterioration of image quality. However, in the present invention, since the magnetic particles having a small particle diameter of less than 35 μm are contained in the developer, the small magnetic particles adhere to the latent image holding member and serve as a polishing effect to remove the toner. There is.

At this time, the magnetic particles are between the compound A positioned in the opposite direction to the non-magnetic toner with respect to the surface of the developer carrying member in the triboelectric charging series, and between the compound A and the non-magnetic toner in the triboelectric charging series. It is more effective when treated with compound B located.

 This point will be described in detail below.

For example, using a negatively chargeable toner, the dark potential V _D1 after primary charging on the latent image carrier is −650 V, and the dark potential V _D after image exposure is V
_{When D2} is −600 V, light portion potential V _L is −200 V, and bias potential V _DC on the developing sleeve is −500 V, the reversal potential during image formation is V _D2 −V _DC = −100 V, and the magnetic particles are Do not develop on latent image carrier. However, if there is toner adhering matter on the latent image carrier, the charges on the latent image carrier will not be attenuated and the charges will be accumulated. The reversal potential at this time is −
When it is higher than 150 V, magnetic particles, especially small-sized magnetic particles, are easily developed on the latent image carrier. As a result, the small-diameter magnetic particles developed on the toner-fixed portion on the latent image holding member act to scrape off the toner-fixed matter, and the image deterioration is eliminated.

Although any latent image carrier can be used in the present invention, it is preferable that the surface thereof has no charge generation layer. That is, in the present invention, the surface of the latent image carrier is inevitably scraped off at the same time when the toner adhered matter is scraped off.Therefore, if the charge generation layer is exposed in the surface layer, the surface is scraped by repeated use. As a result, the sensitivity decreases, which is not preferable. Therefore, in the present invention, it is particularly preferable to use an organic photoconductor (OPC) latent image carrier having a charge transfer layer on its surface.

As the organic photoconductor used in the present invention, one using an organic photoconductive polymer such as polyvinylcarbazole,
And low molecular weight organic photoconductive substances using an insulating polymer as a binder. Among these, a laminated type photoreceptor comprising a charge transfer layer and a charge generation layer is preferably used in the present invention, and the charge generation layer includes azo pigments such as Sudan Red, Diane Blue and Genus Green B, Argol Yellow and Pyrenequinone. , Quinone pigments such as Indanthrene Brilliant Violet RRP,
Quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, bisbenzimidazole pigments such as Indian First Orange toner, phthalocyanine pigments such as copper phthalocyanine, charge generating substances such as quinacridone pigments, polyester, polystyrene, polyvinyl butyral, polyvinyl It is formed by being dispersed in a binder resin such as pyrrolidone, methyl cellulose, polyacrylic acid esters, and cellulose ester. Its thickness is 0.
01 to 1 μm, preferably 0.05 to 0.5 μm.

Further, the charge transfer layer has anthracene on the main chain or side chain,
Pyrene, phenanthrene, polycyclic aromatic structures such as coronene, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole,
It is formed by dissolving a compound having a nitrogen-containing cyclic structure such as triazole and a hole-transporting substance such as a hydrazone compound in a resin having film-forming properties. This is because the charge transfer material generally has a low molecular weight and is poor in film forming property by itself. Examples of such a resin include polycarbonate, polymethacrylic acid esters, polyarylate, polystyrene, polyester, polysulfone, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer and the like. The thickness of charge transfer layer is 5 ~ 20μ
m is preferred. As the resin that constitutes the surface layer of the photoreceptor such as the charge transfer layer, properties such as abrasion resistance and oil lubricity are also important, and from such a point, T _g at the peak position measured by DSC as a resin is important. Is preferably 60 ° C. or higher, particularly 80 ° C. or higher, and further preferably contains 30% by weight or more, particularly 70% by weight or more of a vinyl polymer.

The transfer method used in the present invention includes an electrostatic transfer method,
Known methods such as a bias roll method, a pressure path transfer method, and a magnetic transfer method are used. Further, as a method for cleaning the residual toner on the photoconductor, a blade cleaning method, a fur brush cleaning method, a magnetic brush cleaning method, etc. which are well known in the related art are used. Immediately before reaching the cleaning step, a charge removing step or the like may be provided as necessary to facilitate toner cleaning.

In the image forming method of the present invention, the blade cleaning method is preferable as an excellent combination of the toner of the present invention and the photoconductor. In a particularly preferred embodiment of the present invention, the pressure w / a required for displacing the cleaning blade having the axial length acm of the photoconductor by 1 mm by 1 mm is 5 to 60 g / cm, preferably 8 to 50 g.
This is a method of performing a counter blade cleaning method using an elastic blade in the range of / cm.

Further, in order to fix the toner of the present invention on the transfer member, known methods such as oven fixing, heat roll fixing, pressure fixing, flash fixing, microwave fixing and the like can be applied.

In the production of the toner of the present invention, a method in which the constituent materials are well kneaded by a heat kneader such as a hot roll, a kneader, an extruder, and then mechanical pulverization and classification, or a magnetic powder in a binder resin solution, etc. The method of obtaining the toner by dispersing the above-mentioned material and then spray-drying or a method of mixing the monomer to form the binder resin with a predetermined material and then polymerizing this emulsion suspension to obtain a toner. Each method such as a toner manufacturing method can be applied.

 Hereinafter, a) the description of the developing method, b) the details of the developing mechanism, and c) the constitution of the materials will be described in this order.

a) Description of developing method Hereinafter, the main developing method will be described with reference to Examples. First
The figure shows an example of the developing device used in the present invention. In FIG. 1, 1 is a latent image holding member, 2 is a toner supply container, 3 is a non-magnetic sleeve, 4 is a fixed magnet, 5 is a magnetic or non-magnetic blade, 7 is a magnetic particle circulation region limiting member, and 8 is magnetic particles. , 9 is a non-magnetic toner, 10 is a developer collecting container portion, 11 is a scattering prevention member, 12 is a magnetic member, 13 is a developing area, and 14 is a bias power source. The sleeve 3 rotates in the b direction, and the magnetic particles 8 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 magnetic or non-magnetic blade 5 and the sleeve 3, and is applied onto the non-magnetic 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 same effect as that of substantially increasing the surface area of the sleeve is exhibited.

Further, in the developing area 13, one of the magnetic poles of the fixed magnet 4 is
By facing one to the latent image surface, a clear developing pole is formed, and toner is fly-developed on the sleeve and from the magnetic particles by an alternating electric field. (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 3 may be a paper cylinder or a synthetic resin cylinder, but 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, it can be used as a developing electrode roller.

In the present invention, the coating amount of the magnetic particles on the surface of the downstream sleeve of the magnetic or non-magnetic blade 5 is 5 to 80 mg / cm ² in order to fully utilize both the magnetic brush and the surface of the sleeve 3.
It is desirable that the amount is as small as 10 to 60 mg / cm ² . If the amount of the magnetic particles present on the surface of the sleeve is too large, the regulation force of the blade 5 is weakened, and the rubbing force between the sleeve and the magnetic particles is reduced, so that the toner cannot be charged smoothly. Further, there is a drawback that the magnetic particles also fly during the flight development of the toner and adhere to the latent image carrier 1. Further, as the sleeve peripheral speed becomes faster, the regulation by the fixed magnet becomes weaker and the scattering of the developer becomes remarkable. On the contrary, when the amount of the magnetic particles existing on the sleeve surface in the developing region 13 is too small, the amount of toner applied to the developing region is reduced, resulting in uneven density and image density. The amount of magnetic particles present on the surface of the sleeve can be adjusted mainly by the gap with the sleeve 3, the position of the N ₁ pole of the fixed magnet 4, 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.

m = M / S The developing area refers to an area of 10 mm in the sleeve circumferential direction with the closest part of the latent image carrier and the developer carrier as the center.

The gap d between the tip of the blade 5 and the surface of the developing sleeve 3 at the point 6 is 50 to 650 μm, preferably 100.
~ 600 μm. If this distance d is less than 50 μm,
There is a drawback that the magnetic particles described later become clogged and damage the sleeve. On the other hand, if it is larger than 650 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 7 indicates the lower surface of the blade 5 which is in contact with the upper surface of
A magnetic particle circulation region limiting member having a front end face as an undercut face.

Reference numerals 8 and 9 denote magnetic particles and non-magnetic toner that are sequentially accommodated in the toner supply container 2.

The bottom plate of the toner supply container 2 is extended below the developing sleeve 3, 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 10 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
11 are provided. A voltage described later is applied to this member 11.

The magnetic particles 8 generally have a volume average particle size of 35 to 65 μm, preferably 40 to 55 μm. When the volume average particle diameter is smaller than 35 μm, the magnetic particles are easily developed on the latent image holding member and the latent image holding member and the cleaning blade are easily damaged. On the other hand, when the volume average particle diameter is larger than 65 μm, the toner holding ability of the magnetic particles is lowered, and non-uniformity of solid image, toner scattering, fog and the like occur.

In the present invention, the magnetic particles have a volume particle size distribution of 35
The effect is remarkable when the content of the particles less than μm is 5 to 25% by weight, preferably 7 to 20% by weight. That is, if the particle size of less than 35 μm is less than 5% by weight, the polishing effect of the magnetic particles does not last long and image deterioration due to durability occurs, and if it exceeds 25% by weight, scratches on the latent image carrier occur or It causes harmful effects such as excessive scraping. Magnetic particles with a particle size of less than 35 μm
As a means for increasing the number of magnetic particles of 40 μm, it is preferable to adjust the particle size distribution at the stage of firing the magnetic particles, but magnetic particles having a particle size of less than 35 μm may be separately added and uniformly mixed.

The particle size distribution in the present invention was measured according to JIS H2601 as follows.

1) Weigh about 100 g of sample to the order of 0.1 g.

2) Use a 100-500-mesh standard sieve (hereinafter referred to as a sieve) as the sieve, stack from the top in the order of 100,200,250,350,400,500, place a saucer on the bottom, put the sample on the top sieve and cover. .

3) This is oscillated by a vibrating machine to rotate horizontally at 285 ± 6 times per minute,
Sift for 15 minutes at 150 ± 10 impulses per minute.

4) After sieving, weigh out the magnetic particles in each sieve and the pan to the order of 0.1 g.

5) Calculate to the second decimal place by weight percentage and round to the first decimal place according to JIS Z8401.

Remarks: The size of the frame of the sieve is such that the inner diameter above the sieve surface is 200 mm and the depth from the top surface to the sieve surface is 45 mm.

, The total weight of magnetic particles in each part must not be less than 99% of the weight of the sample initially taken.

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 introducing the magnetic particles 8 into the toner supply container 2, the magnetic particles 8 from the toner supply container 2 in which the sleeve surface region where the magnetic particles 8 face the inside of the container 2, that is, the sleeve 3 is disposed. Or magnetic material to prevent toner leakage
The sleeve surface region from 12 to the tip of the blade 5, which is the magnetic particle restraining member, is attracted and held by the magnetic field generated by the magnet 4 in the sleeve 3 to cover the entire sleeve surface region as a magnetic particle layer. The non-magnetic toner 9 is stored in a large amount outside the magnetic particle layer as the first layer with respect to the sleeve 3 by being charged into the container 2 after the magnetic particles 8 are charged, and is present as the second layer.

The magnetic particles 8 to be initially charged preferably originally contain about 2 to 30% by weight of the non-magnetic toner 9 with respect to the magnetic particles, but may include only the magnetic particles. Further, once the magnetic particles 8 are adsorbed and held as a magnetic particle layer in the sleeve surface area, they do not substantially flow to one side even if the apparatus is vibrated or the apparatus is tilted to a large extent. The state of covering the whole is maintained.

Thus, in the state where the magnetic particles 8 and the non-magnetic toner 9 are sequentially charged and stored in the container 2 as described above, the magnetic particle layer portion near the sleeve surface corresponding to the magnetic pole S ₂ position of the magnet 4 has a strong magnetic pole. The magnetic field forms a magnetic brush of magnetic particles.

Further, the magnetic particle layer portion in the vicinity of the tip of the blade 5 serving as a magnetic particle regulating member has a regulating force based on the effect of gravity and magnetic force and the presence of the blade 5 even if the sleeve 3 is rotationally driven in the direction of the arrow b, and the sleeve. Due to the balance with the conveying force of 3 in the moving direction, it accumulates at the point 6 position on the surface of the sleeve 3 and forms a stationary layer which can move a little but is difficult to move.

When the sleeve 3 is rotated in the direction of the arrow b, the magnetic brush can be moved in the vicinity of the magnetic pole S ₂ by appropriately selecting the position of the magnetic pole and the fluidity and magnetic characteristics of the magnetic particles 8.
Circulating in the direction to form a circulating layer. In the circulation layer,
The magnetic particles that are relatively close to the sleeve 3 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 3 by the rotation of the sleeve 3. That is, it receives the force of pushing it up. The amount of the magnetic particles thus pushed up is determined by the magnetic particle circulation region limiting member 7 provided on the upper part of the blade 5, and the upper limit of the circulation region is determined. Then
Return to the vicinity of the magnetic pole S ₂ again. In this case, the magnetic particles having a small push-up force, such as being located far from the sleeve surface, may fall before reaching the magnetic particle circulation region limiting member 7. That is, in the circulation layer, the magnetic brush of magnetic particles is circulated as indicated by an arrow c due to the magnetic force and frictional force due to gravity and magnetic poles and the fluidity (viscosity) of the magnetic particles. The non-magnetic toner 9 is sequentially taken in from the toner layer above the developer supply container 2
Returning to the lower part of the inside, the circulation is repeated as the sleeve 3 is driven to rotate.

b) Details of developing mechanism The phenomenon in the developing section 13 will be described below regarding the reversal 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. Reference numeral 21 is the latent image charge in the dark area on the latent image carrier. 9 is a non-magnetic toner. 14 is an alternating voltage power source on which a DC component is superimposed. FIG. 2 shows a case where a negative waveform component of the alternating voltage is applied to the sleeve 3, and FIG. 3 shows a case where a positive 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 negative.

Since the resistance of the developing brush 22 is relatively large (greater than about 10 ⁸ Ωcm), the developing brush 22 depends on the charging / discharging time constant of the electric charge due to the material of the developing brush 22 itself, etc. Alternatively, there is an electric charge injected by the mirror charge, the latent image electric field on the latent image carrier 1 and the alternating electric field between the latent image carrier 1 and the sleeve 3.

When the electric field due to the latent image charge 21 in the dark portion on the latent image carrier 1 and the electric field due to the alternating electric field do not match, the developing brush 22 is in the maximum sagging state in the sleeve 3 direction.

When the direction of the electric field due to the latent image charge on the latent image carrier 1 and the direction of the electric field due to the alternating electric field coincide with each other, the yield of the developing brush 22 becomes small and the developing brush 22 comes into contact with the latent image carrier.

In any case, as described above, the developing brush is generated by the alternating electric field.
22 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 1, and pulled back onto the brush. Further, due to the above-mentioned vibration of the brush, the toner easily comes off from the brush 22 and is easily supplied to the latent image holding body 1, so that the image density also improves. Further, the above vibration of the brush 22 loosens the toner in the brush 22,
This contributes to improvement of image density and prevention of ghost. Further, when this vibration 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.

c) Composition of Material The magnetic particles for toner application used in the present invention include:
For example, surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium, and rare earths, and alloys or oxides thereof can be used, but preferably metal oxides, more preferably ferrite particles can be used.
There is no particular restriction on the manufacturing method.

The compounds A and B 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 is Tetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, and their copolymers, silicone resin, polyester resin, metal complex of ditertiary butyl salicylic acid, etc. As compound B, styrene resin, acrylic resin, polyamide , A silicone resin, polyvinyl butyral, etc., and the toner is negatively charged, the compound A is nigrosine, an amino acrylate resin, an acrylic resin, a basic dye and its lake, and the compound B is a styrene resin, a silicone. Butter, although it is appropriate to use such a polyester resin is not necessarily constrained thereto.
The present inventors believe that the compound A gives a sufficient electric charge to the toner, strongly takes in the toner around the magnetic particles to prevent fog and toner scattering, and the compound B plays a role of controlling it. ing.

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 or a substance for surface treatment of the magnetic particles is placed 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). 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, like the toner carrier, does not have its own triboelectrification property) is 1: 9. Metal lid 14 containing about 4g of mixture (developer)
do. Weigh the entire measuring container 2 at this time W ₁ (g)
And 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 to adjust the air volume control valve 16 to adjust the pressure of the vacuum gauge 15 to 700 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). In addition, the total weight of the measurement 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 60% RH.

On the other hand, as the binder resin of the toner used in the present invention, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and its substitution products; styrene-p-chlorostyrene copolymer, styrene-propylene. Copolymer, styrene-vinyltoluene copolymer,
Styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer Polymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-acryl-aminoacrylic copolymer, styrene-aminoacrylic copolymer, styrene-α-methyl chloromethacrylate copolymer Coalesce, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinyl ethyl ether copolymer, styrene-
Styrene type such as vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Copolymer; polymethylmethacrylate, polybutylmethacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol Resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins and paraffin waxes can 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 dyes and pigments such as carbon black, iron black, phthalocyanine blue, ultramarine, 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. Parts shown in the examples are parts by weight.

 As the developing device, the one shown in FIG. 1 was used.

In the apparatus of the embodiment, the photosensitive drum 1 is 60 in the direction of arrow a.
It rotates at a peripheral speed of mm / sec. 3 is 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 (S
US304) sleeve, the surface of which was subjected to irregular sandblasting using # 600 alundum abrasive grains, and the circumferential surface roughness was set to 0.8 μm (R _Z =). On the other hand, a ferrite sintered type magnet 4 is fixedly arranged in the rotating sleeve 3, 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 blade 5 used was 1.2 mm thick non-magnetic stainless steel. Blade sleeve gap is 300
μm. A photosensitive drum made of an organic semiconductor having a charge transfer layer of 10 μm in the surface layer is used as the latent image carrier 1 facing the sleeve 3, and the dark area potential after primary charging is used.
An electrostatic latent image was formed with V _{D1 set} to −650 V, dark part potential V _D2 after image exposure set to −600 V, and light part potential V _{L set} to −100 V, and the distance from the sleeve surface was set to 300 μm. And the frequency of 1500Hz, peak-to-peak value by the power supply 14 to the above sleeve
At 1.4 kV, a voltage having a center value of -500 V was applied to carry out reversal development.

The residual toner on the latent image carrier was removed by using a counter blade cleaning method. The hardness w / a of the blade used was 25 g / cm.

Example 1 0.5% of colloidal silica was added to the red powder having a volume average particle diameter of 12 μm as described above to obtain a toner. The triboelectric charge amount of the toner was −23.7 (μC / g).

Next, 100 parts of ferrite particles having a particle diameter of 40 to 60 μm as magnetic particles were added to a styrene-methyl methacrylate copolymer (30:70) (friction charge amount = +1.3 μC / g) 1 part Polyvinylidene fluoride (friction charge amount -11.5 μC / g) 1 part was dipped in a dispersed and dissolved xylene solution, and heated and dried with stirring to prepare. The volume average particle diameter of the magnetic particles was 42 μm, the volume particle diameter distribution was less than 35 μm 13% by weight, and the particle diameter 35-40 μm was 8% by weight.

First, 10 parts of the toner and 100 parts of the magnetic particles are mixed,
When the image was applied to the developing device shown in the figure, a clear image with good gradation and no gradation was obtained, and the image reflection density was 1.30. Further, when 10,000 sheets were subjected to durability test to check the durability of the developer, a clear image (image density 1.25) without fog similar to the initial stage was obtained, and toner scattering was also good. On the other hand, high temperature and high humidity environment (30 ℃, 90% R
Under the same condition, the image density was 1.1.
In 5, an image with no problems such as fog was obtained. In addition, a clear and fog-free image was obtained even in a low temperature and low humidity environment (15 ° C, 10%).

Example 2 Example 1 except that the coating resin for the magnetic particles was 1.2 parts of polymethylmethacrylate (triboelectric charge = + 6.5 μC / g) and 0.5 part of polytetrafluoroethylene (triboelectric charge = −4.6 μC / g). The same good result was obtained.

Comparative Example 1 The procedure of Example 1 was repeated except that the volume particle size distribution was 3% by weight for particles having a particle size of less than 35 μm and 7% for particles having a particle size of 35-40 μm. After that, toner adhesion to the latent image carrier was recognized.

Comparative Example 2 The procedure of Example 1 was repeated, except that the volume particle size distribution was less than 35 μm and the particle size was less than 35 μm.
After 00 sheets, the latent image bearing member was scratched due to the magnetic particles.

[Effects of the Invention] As described above, according to the present invention, with a simple configuration,
An excellent image with high density can be obtained from the beginning, and there is no filming or cleaning failure of the latent image carrier even by durability.
A developer and an image forming method having excellent cleaning properties can be obtained.

[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 a frictional charge amount measuring device. FIG. DESCRIPTION OF SYMBOLS 1 ... Latent image holder, 2 ... Developer supply container, 3 ... Non-magnetic sleeve, 4 ... Fixed magnet, 5 ... Blade, 7 ... Magnetic particle circulation region limiting member, 8 ... Magnetic particles, 9 ... Non-magnetic toner, 10 ... developer collecting container portion, 11 ... scattering prevention member, 12 ... magnetic member, 13
... Development area, 14 ... Bias power supply, 21 ... Electrostatic latent image, 22 ... Magnetic brush, 41 ... Suction machine, 42 ... Measuring container, 43 ... Conductive screen, 44 ... Lid, 45 ... Vacuum gauge, 46 ... Air volume adjustment Valve, 47 ...
Suction port, 48 ... condenser, 49 ... electrometer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 9/10 13/09 15/08 507 L G03G 9/08 344 321 (72) Inventor Mitsuru Uchida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Ryoichi Fujita, Ota-ku, Tokyo Shimomaruko 3-30-2 Canon Inc. (56) Reference JP-A-60-87349 (JP, A) JP-A-61-149971 (JP, A) JP-A-61-204645 (JP, A) JP-A-61-204646 (JP, A) JP-A-58-195863 (JP, A) JP-A-60-241072 (JP, A) JP-A-60-222873 (JP, A) JP-A-61-133952 (JP, A) JP-A-60-131545 ( JP, A) JP 61-118767 (JP, A) JP 61-6665 (JP, A) JP 55-3060 (JP, A)

Claims (4)

[Claims] 1. A latent image is formed by applying an alternating electric field between the developer carrying body and the latent image carrying body in a developing area of the developer carrying body facing the latent image carrying body for holding the latent image. In a developer comprising at least a non-magnetic toner and magnetic particles used in an image forming method of developing with a non-magnetic toner, the magnetic particles have a direction opposite to that of the non-magnetic toner with respect to the surface of the developer carrier in the triboelectric charging series. And a compound B located between the compound A and the non-magnetic toner in the triboelectric series, the volume average particle diameter of the magnetic particles is 35 to 65 μm, and 5 to 25% by weight of particles with a particle size distribution of less than 35 μm and a particle size of 35
A dry developer characterized in that particles having a size of -40 μm are smaller than particles having a particle size of less than 35 μm. 2. A latent image is formed by applying an alternating electric field between the developer carrying member and the latent image holding member in a developing area of the developer holding member facing the latent image holding member for holding the latent image. In an image forming method of developing with a non-magnetic toner, a compound A located in the opposite direction to the non-magnetic toner with respect to the surface of the developer carrier in the triboelectric charging series, the compound A and the non-magnetic toner in the triboelectric charging series Is treated with compound B located between and, and the volume average particle size is 35 to 65 μm,
5 to 25% by weight of the particles having a volume particle size distribution of less than 35 μm and less magnetic particles having a particle size of 35 to 40 μm than those having a particle size of less than 35 μm in the developing area of the developer carrier,
A magnetic brush is formed so that the amount of the magnetic particles present is 5 to 80 mg / cm ^2, and the magnetic brush is formed on the latent image carrier, the surface of the developer carrier and the surface of the developer carrier in the developing area. From the process of reversing and developing the latent image while reciprocating the non-magnetic toner with the surface, the process of transferring the image on the latent image carrier to the transfer member, and the process of removing the residual developer on the latent image carrier. An image forming method comprising: 3. The image forming method according to claim 2, wherein the latent image carrier contains an organic polymer having a charge transfer layer on its surface. 4. The image forming method according to claim 2, wherein the step of removing the residual developer on the latent image holding member is performed by a counter blade cleaning method.