JP2835650B2 - Dry electrostatic recording toner composition - Google Patents

Description

The present invention relates to a toner composition comprising fusible, electrostatically attractable toner particles suitable for developing electrostatic charge patterns.

In the art of electrography and electrophotography copying and printing, forming on a photoconductive member an electrostatic latent image corresponding to the original to be copied or to digitized data containing an electronically available image. Is well known. In another imaging method, an electrostatic latent image is formed by image-wise discharging with a needle directed at a dielectric substrate.
Zero printing, for example, as described in European Patent Application No. 0243934, involves exposing a photosensitive polymer substrate imagewise, charging on a conductive support, toning with a dry or wet toner, toning another substrate. Transfer to

The electrostatic latent image can be developed using a liquid developer comprising a colloidal system of charged colloidal particles in an insulating liquid. In most cases, the latent image is developed with a finely divided developing material or toner to form a powder image, which is then transferred onto a support sheet, such as paper. The support sheet carrying the toner powder image then passes through a fusing device and is then discharged on a corresponding printing machine as a final print corresponding to a final copy.

Electrostatographic proces
As is clear from the above overview of s), two essential steps must be considered: first, the latent electrostatic recording image is formed on a suitable member, for example a photoconductive drum. Second, the latent image is developed into a visually identifiable image and transferred to a final hard copy at a transfer station.

One of the goals described above for general electronic recording is that:
The purpose is to provide an image on the final print corresponding to the final copy having the best possible quality.

By "quality" in an electronic record is generally understood a true faithful reproduction of the original to be copied, or a faithful visual print of an electronically available image.

Thus, quality includes features such as uniform darkness of image areas, background quality, sharp contours of lines, and overall resolution of the image.

In optoelectronic printing devices, the quality, particularly the resolution of the latent electrostatic image, depends on the accuracy of each of the following steps:
Is the conversion of digitized data to fill an appropriate illumination pattern with an electronically available image; the second is the illumination of the photoconductive drum by a light emitting diode device or a laser; and the third is the photoconductive drum. The resolution of the photoconductive step above. In the case of a zero printing device, the quality of the latent electrostatic image depends on the contact exposure process.

In a copying machine, the quality of a latent electrostatic image is
The accuracy of the illumination of the photoconductive drum by the optical device is largely determined, so that the optical quality of the mirrors, lenses, optical fibers, etc. used and the stiffness, robustness and vibration-free structure of the structure play an important role. Accomplish.

The Local Press Ltd., London, 1975, RMSc
Haffert, Electrophotography enlarged and revised edition, page 93, 2.1
As described in Section 5.8 Resolution, the resolution of the latent electrostatic image on a xerographic plate, such as an amorphous selenium plate, is inherently very high because the photoconductive film is essentially particle-free. . The same is true for molecular organic photoconductive materials.

In addition, the first step in the overall electrostatographic process, i.e., the illumination of the photoconductive drum, is to obtain the overall xerographic print in most cases when the necessary precautions are taken for the overall configuration of the device. There is no limiting factor on the resolution achieved.

Since the illumination of the photoconductive drum and the photoconductive drum itself do not limit the resolution of the final print or copy resulting from general electrostatography, a critical factor for overall image quality is The second step in electrophotography is the conversion of the latent image into a visually identifiable image.

Latent electrostatic recording images formed by either electronic printing or copiers are developed into visually identifiable copies, the overall accuracy of which depends primarily on the properties of the developer used.

It is known that one of the properties mainly involved in the past lies in the particle size and precision distribution of the developer particles used, and particularly when the two-component developer material is used, the particle size and particle size distribution of the toner particles used. Have been.

Effect of Toner Shape, published by ATR Corporation of El Dorado, California, USA
The on Image Quality tests the effect of toner particle diameter and shape on image quality, especially for high resolution.

For developers to be used in high resolution laser beam printers, the effect of toner particle size and shape on the image was experimentally tested. As a result, it has been shown that, apart from the shape of the toner and its charge distribution, fine particles are most effective in providing high resolution.

This fact, known per se, has led to some prior art proposals for the production of fine toner particles and especially for toner particles whose particle size distributions meet well-defined grades.

U.S. Pat. No. 3,942,795 (assigned to Xerox Corporation) states that less than about 30% of the number of toner particles has an average particle diameter of less than about 5μ and about 25% of the number of particles.
A toner material is claimed having a particle size distribution such that% has a diameter between about 8μ / about 12μ and less than about 5% of the number of toner particles has an average particle diameter greater than about 20μ.

According to a preferred embodiment of the invention described in said patent, less than about 10% of the number of toner particles has an average particle diameter of less than about 5μ, and about 60% of the number of toner particles is between about 8 and about
It has an average particle diameter of between 12μ and about 5% of the number of toner particles.
% Have an average particle diameter greater than about 20μ.

U.S. Pat. No. 4,284,701 (assigned to IBM Corporation) has less than 15% by weight greater than 16 [mu], 7-15% by weight less than 5 [mu], and a balance of 5-5%.
A toner particle with a particle size distribution of 16μ and a median particle size by weight of 8 to 12μ is claimed.

It is generally known that the resolution of an electrostatographic print is determined by the average particle size or median particle size of the toner particles, apart from the particle size distribution of the toner particles, so that the production and use of extremely fine developer materials is important. Efforts have been made.

However, the smaller the average particle size of the toner particles, or the greater the fraction of very small toner particles in the overall toner, the greater the tendency of the toner and the overall developer composition to aggregate or together. The tendency to gather increases. Thus, the limited flow characteristics of dry electrostatic toners are a limiting factor for the use of very fine toner particles. Therefore, when a high resolution is set as a predetermined requirement in individual electrophotography, a liquid developer composition is often used.

In fact, 0.25 to make very high resolution electrostatic prints
Liquid developer compositions with toner particles having a fine average or median particle size of μ are known. Aggregation can be prevented by those skilled in the art by optimizing the colloidal power. Liquid developer compositions suitable for use in developing electrostatic charge patterns are described, for example, in U.S. Pat.
Nos. 4 and 4138351 (both assigned to Agfa Kevelt NVi in Mortzere, Belgium).

However, liquid developers present a significant drawback: they must be carried with the toner and at the same time evaporate the dielectric solvent adhering to the electrostatographic print, and then recirculated or discarded to the atmosphere to obtain a dry final print. Must.

Compared to dry electrostatography, electrostatographic devices that use liquid developers necessarily entail great disadvantages for consumers.

Accordingly, despite the limited flow characteristics of very fine dry electrostatic recording toner particles, efforts have been made to produce such fine toners.

GB 2180948 describes the use of toner particles having a particle size of less than 5μ. With the use of such small toner particles, the resolution of the image was 10 lines / mm. On the other hand, when the toner particle size is about 10 μm, it is 5 lines / mm.
To avoid sticking of toner particles to the image bearing member, a lubricant,
For example, zinc stearate should be added in an amount of at least 0.5% by weight.

European Patent Application No. 0 257 716 describes a process for producing fine toner particles having uniform spherical particles.
According to said patent application, Coulter Counter (Coulte
The volume average particle size according to the (r Counter) method is 1.0 to 7.0 μ, and the number average particle size is 1.0 to 5.0 μ.

In order to have improved fluidity and charging properties, the toner particles are produced by a complex suspension polymerization method.U.S. Pat.No. 4,734,733 discloses an electrostatic recording method using toner particles having an average diameter of less than 10 .mu. Is described. According to this patent, significant difficulties arise when attempting to transfer toner particles having an average diameter of less than 10μ from an image bearing member to a paper support at an electronic recording transfer station,
Suitable measures have been proposed.

Japanese Patent Application No. 60-192711 records the formation of a sharp image having excellent resolution by electrophotography. According to this document, toner particles having a particle size of 1 to 5 μm are used. The development of the latent image on the photoconductive drum occurs without contact between the photoconductive drum and the thin developer layer application means.

Accordingly, it is an object of the present invention to provide a dry developer material that exhibits superior performance over prior art dry developer materials due to the overall quality of the final electrostatographic print and the overall performance of the electrostatographic process. It is in.

The object of the present inventors is to provide: (I) at least 90% by volume of toner particles have a particle size diameter of more than 0.5μ and less than 7μ; (II) at least about 50% by volume of toner particles have a particle diameter of less than about 5μ. A classified toner material having a particle size distribution of at least 0.1% by weight on their surface.
The flow enhancing additive at a concentration of at most 5% by weight, said methanol having a specific surface area (Am ² / g) which satisfies the following relationship: A × B> 10,000 (B% volume) , And the ratio of the apparent density to the bulk density of the toner particles is Is achieved by providing an electrophotographic toner material characterized in that

According to a preferred embodiment of the present invention, 90% of the toner particles
More than 50% by volume has a particle size diameter of greater than 0.5μ and less than 6μ, and more than about 50% by volume of the toner particles have a particle size diameter of less than about 4μ.

According to a further preferred embodiment, at least 90% by volume of the toner particles have a particle size diameter of greater than 0.5μ and less than 5μ, and at least about 50% by volume of the toner particles have a particle size diameter of less than about 3μ.

According to a further preferred embodiment, the toner particles are mixed with a flow-enhancing additive, which is coated with hydrophobic group-containing units giving a methanol value of more than 20.

A further preferred embodiment comprises a toner with a mixed flow enhancer having a specific surface area of 150 m ² / g or less.

Suitable toner compositions for use in accordance with the present invention should be prepared by selecting and modifying from several known toner mixing and milling methods. As is generally known, the toner is made by continuously mixing the components in a dissolved state, and after cooling, pulverizing and pulverizing the formed mixture. Thereafter, a suitable particle classification method is used so as to obtain toner particles having a predetermined particle size. Representative classification methods include air classification, sieving, cyclone separation, drainage, centrifugation and combinations thereof.

The preferred method of obtaining very fine toner particles of the present invention is by centrifugal air classification.

Suitable pulverization and air classification are, as air classification means,
ATP (Alpine Turboplex windsichter) type 50G.S.
AFG (Alpine Fliessb)
eth Gegenstrahlmuehle) obtained when using a combination device such as type 100. These devices are available from Alpine Process Technology Limited of Industrial Estate in Cheshire, Runcorn, Living Road, White House, and the United Kingdom. In addition, for air classification, A100MZR (Alepine Multiplex L
abor Zickzack sichter). This equipment is also available from Alpine Process Technology Limited. The particle size distribution of the toner particles thus obtained is shown by Coulter Electronics of Northwell Drive, Bedfordshire, Luton, UK.
It can be measured by a usual method using a Coulter counter type TA II / PCA1 available from Corporation.

In an air classifier, using air or other gas as the transport medium, the particles contained in the fluid medium have two antagonistic forces: a traction force directed inside the medium and a centrifugal force directed outside the particles. Exposed to power. Both forces are in equilibrium because of the defined size of the particles, the cut size.
Large (heavy) particles are dominated by mass-dependent centrifugal forces, and small (light) particles are dominated by frictional forces that are proportional to particle diameter. Thus, larger or heavier particles fly outward as a coarse fraction, while smaller or lighter particles are carried inward by air as a fine fraction. The cut size is usually determined by geometric parameters and operating parameters (classification dimensions, rotor, rotation speed, etc.). The cut size can be determined by changing the aforementioned parameters.

By applying the above-described manufacturing method, the toner particles are described in the claims and can be manufactured according to the particle size distribution described above. However, these toner particles can be used as they are, because of their fluidity and electrostatic capacity shown here. This indicates a problem when used in electronic recording copying or printing equipment due to the inadequate overall performance of the recording method.

The present inventors have found that by adding a suitable flow improver in a selected manner, the flowability of the toner particles thus produced is improved.
It has been found that the toner particles can be sufficiently enhanced so as to obtain toner particles suitable for use in an electrostatic recording apparatus.

To improve the flow characteristics of the toner, the toner particles may be mixed with a flow enhancing additive. These additives are mainly extremely fine inorganic or organic materials. Widely used in this regard are fumed inorganic materials such as silica, alumina or zirconium oxide or titanium oxide. The use of silica as a flow improver for toner compositions is described in U.S. Patent No. 1,438,110.

The fumed silica particles used in the toner composition of the present invention are essentially spherical and are coated with a hydrophobic layer such as that obtained by the reaction between various types and volumes of silane and the silanol groups of the silica-based microparticles. Having a flat surface. See European Patent No. 023409 of the Torre Silicone Company. Other microparticles can be used and exhibit comparable properties and manufacturing methods.

The type of surface can be varied and the extent of coverage can be varied. Where scientifically reacted coatings are preferred, physically adsorbed coatings also meet the requirements of the present invention, but have the potential to form films on image bearing members and other mechanical parts when developed over time. Shows the major drawbacks. Fifteen
Fumed silica particles having a surface area of 0 m ² / g or more and a methanol value of 20 or more are Aerosil and trade names Aerosil, marketed by Degussa GmbH of Frankfurt, Germany and Cabot Corporation, Boston, Mass., Respectively. CAB
-O-SIL is commercially available. Aerosil R972 is 110m ² / g
Is a representative example of a fumed hydrophobic silica having a specific surface area of and a methanol value of 40.

The specific surface area is 30 volumes of Analytical Chemistry, No. 8 (1958
Year), pp. 1387-1390, Determination of Surface Are
a Adsorption Measurements by continuous flow metho
It can be measured by the method published by Nelsen and Eggertzen under d.

The methanol value can be measured by the following method. Place 200 mg of powder and 50 ml of water in a 250 ml shake flask, add magnetic stirring, and add methanol at a rate not exceeding 10 ml / min. The end point of the titration is the point at which all the powder is suspended (xml)
And the methanol value (B) is calculated as follows: Commercially available types and specially made samples were used in the present invention.

The preferred ratio of fumed silica to toner material ranges from 0.5 to 3% by weight.

In addition to fumed silica, for example, U.S. Pat.
Metal soaps such as those described in No. 2, for example zinc stearate, can also be used as additional flow improvers. Other flow improving additives are based on submicron sized fluorine-containing polymer particles.

The preferred ratio of metal soap such as zinc stearate to the toner material is in the range of 0.05 to 1% by weight. The same is true for fluorine-containing particles.

The toner compositions used according to the invention are described, for example, in European Patent Applications 0128569, 0170421 and 8920019.
Conventional resin binders such as those described in 2.6 can be included. An interesting example is European Patent Application No. 02
No. 79960, which includes (1) styrene or a styrene homolog, (2) an alkyl acrylate or alkyl methacrylate monomer in which the alkyl chain is linear and contains at least 8 carbon atoms, and (3) at least It is a copolymer of a cross-linking monomer containing two ethylenically unsaturated groups. Partially cross-linked polyesters are also of interest, e.g. published UK patent application no.
No. 82788A, for example, binder compositions derived from terephthalic acid polycondensed with less than one equivalent of ethoxylated and / or propoxylated bisphenol A. Further, other ordinary polymers suitable for use as a binder in the toner particles can be used.

Other resins or pigments and / or release agents that modify the melt particle size can be used to further improve the properties of the toner. Advantageously, especially when using a heated roller fusing apparatus, an additional release agent should be incorporated into the toner composition to help release the toner melt from the fusing roller. Particularly suitable release agents are tack-free promoting compounds such as talc, silicone, fluorine-containing polymers and natural or synthetic waxes.

To prevent toner offset on the fuser roller, suitable fluorine-containing vinyl polymers, particularly having a low coefficient of friction (less than 0.2 static coefficient of friction against steel), are disclosed in US Pat.
No. 4059768.

Particularly suitable for preventing toner offset are waxy polyalkylene resins, more particularly isotactic polypropylene having an average molecular weight of less than 15,000.

The coloring material used in the toner particles can be any inorganic pigment (including carbon) or solid organic pigment or dye commonly used in dry electrostatic toner compositions, or mixtures thereof. For example, carbon black and its congeners, such as lamp black, channel black and furnace black, such as SPEZIALSCHWARZ IV
(Trade name of Degussa in Frankfurt, Germany) and C
ABOT REGAL 400 (trade name of Cabot Corp., Boston, USA) can be used.

The addition of a colorant can also affect the melt viscosity of the toner. If desired, the addition of a colorant may be considered to bring the melt viscosity of the toner into a desired range. The colorant is added to and mixed with the molten toner composition. It is crushed when cooled and crushed to obtain the desired particle size.

Apart from the colorants mentioned above, the use of viscosity-modifying pigments can be taken into account. Types of interest for that purpose include titanium dioxide (rutile), barium sulfate (barite), calcium carbonate (calcite), ferric oxide (Fe
Other magnetic or magnetizable pigments, including ₂ O ₃ , fematite) and ferric oxide (Fe ₃ O ₄ , magnetite), cupric oxide, can also be used.

The latter pigments can also act, for example, as coloring substances in magnetic toners. Accordingly, the present invention includes a toner in which one or more coloring substances are present.

Typical solid organic dyes used in electrophotographic toners are
It is a so-called pigment dye, which includes phthalocyanine dyes such as copper phthalocyanine, metal-free phthalocyanines, azo dyes and metal complex salts of azo dyes.

The following dyes in the form of pigments are shown for illustrative purposes only: FANALROSA B Supra Pulver (trade name of BASF AG in Ludwigshaus Halfen, Germany), HELIOGENBLAU LG
(Trade name of BASF AG for metal-free phthalocyanine blue pigment), MONASTRAL BLUE (copper phthalocyanine pigment, C.I.
I.74160), HELIOGENBLAU B Pulver (trade name of BASF AG), HELIOGENBLAU HG (trade name of Bayer AG of Leverkusen, Germany for copper phthalocyanine, CI74160), BRI
LLIANT CARMIN 6B (CI18850) and VIOLET FANAL R
(Trade name of BASF AG, CI42535).

Typical inorganic pigments used in electrophotography include carbon black, black iron oxide (III) and mixed copper oxide (II).
/ Chromium (III) oxide / iron (III) oxide powder, including Miloli Blue, Ultramarine Cobalt Blue and barium permanganate. Further, French Patent No. 1394061 filed on Dec. 23, 1963 by Kobak Ltd. and Harris In
Mention may be made of the pigments described in French patent 1439323 filed on April 27, 1965 by lertype Corporation.

The coloring substance is usually 5% calculated on the total weight of the toner.
Use in a concentration range of ~ 20% by weight.

Apart from insoluble coloring substances, the use of soluble coloring substances is also conceivable.

A charge control agent is added to the toner particle composition to enhance the negative or positive charge of the toner particles. For example, to produce negatively chargeable toner particles, for example, a charge control agent as described in published German patent application (DE-OS) 3022333, or to produce positively chargeable toner particles, Charge control agents are added, for example as described in published German patent application (DE-OS) 2362410 and U.S. Pat. Nos. 4,263,389 and 4,264,702. A very useful charge control agent for imparting positive charge polarity is BONTRON NO4 (trade name of Oriental Chemical Industry in Japan), which is used in an amount of up to 5% by weight, based on the toner particle composition. A resin acid-modified nigrosine dye that can be used. A very useful charge control agent to provide negative charge polarity is BONTRON S36 (trade name of Oriental Chemical Industry in Japan), which is used for toner particle compositions.
For example, metal complex dyes which can be used in amounts up to 5% by weight.

In the production of toner particles, the coloring material and other additives are added to the molten resin and kneaded until a homogeneous mixture is obtained. The solid mass obtained after cooling is crushed and crushed, for example in a hammer mill, followed by a jet mill. After this operation, air classification was performed.

For a given charge density on the latent image charge carrying surface, the highest development density obtained with a given particle size toner particle is the charge / charge
It is determined by the toner particle mass ratio. This is substantially determined in the case of a two-component developer by the triboelectric charge obtained by frictional contact with the carrier particles.

The toner compositions of the present invention should preferably be used in combination with carrier particles.

Development can be effected by so-called cascading of the toner particles on the imaging surface containing the electrostatic charge pattern or by using a magnetic brush. As long as the carrier particles can triboelectrically acquire a charge of opposite polarity to the polarity of the toner particles so that the toner particles adhere to and surround the carrier particles.
It can be electrically conductive, insulating, magnetic or non-magnetic (although for magnetic brush development they must be magnetic).

In developing the electrostatic image to form a positive reproduction of the original, the carrier particle composition and / or the toner particle composition are selected such that the toner particles obtain a charge having a polarity opposite to that of the electrostatic latent image. I do. Thus, toner adhesion occurs in the image area. Instead, in the inversion reproduction of the electrostatic latent image, the carrier composition and the toner particle composition are selected such that the toner particles obtain a charge having the same polarity as the polarity of the electrostatic latent image, and the non-image area is formed. Causes toner adhesion.

Useful carrier materials for cascade development include sodium chloride, ammonium chloride, potassium aluminum chloride, Roschel's salt, sodium nitrate, aluminum nitrate, sodium chlorate, particulate zircon, particulate silicon, silica, methyl methacrylate, glass. Useful carrier materials for magnetic brush development include copper, nickel, iron, ferrite, ferromagnetic materials, such as magnetite, with or without a polymer coating. Other suitable carrier particles include a magnetic or magnetizable material dispersed in a binder in the form of a powder, as described, for example, in US Pat. No. 4,600,675. Many of the aforementioned and representative carriers are described in U.S. Pat.Nos. 2,618,441, 2,684,416, 2,615,522, 3,359,150 for conductive carrier coatings.
No. 3,533,835 and in U.S. Pat. No. 3,526,533 for polymer-coated carriers. Oxide coated iron powder carrier particles are described, for example, in US Pat. No. 3,767,777. U.S. Pat.
No. 3767578 relate to nickel-based carrier beads. Preferably, the diameter of the final coated carrier particles is from about 30μ to about 1000μ. At this time, the carrier particles have sufficient inertia to avoid adhesion to the electrostatic image during the cascade development process, and withstand the losses due to centrifugal forces operating in magnetic brush development. The carrier can be used with the toner composition in any suitable combination, and generally satisfactory results have been obtained when about 1 part by weight of toner particles is used with about 5 to 200 parts by weight of the carrier.

The toner compositions of the present invention can be used to develop electrostatic latent images on any suitable electrostatically charged surface capable of retaining charge, especially photoconductive layers known to those of ordinary skill in the art, including conventional photoconductors. it can.

The hot roll melting of toner can be performed, for example, by using the Journal of Imaging
Technology Volume II, Issue 6, (December 1985), p. 261-
It is described on page 279. The heated roller fusing method and electrostatic recording apparatus for carrying out this method are described in detail in the aforementioned European Patent Application No. 0279960, while infrared fusing is described in US Pat. No. 4,525,455.

The following examples illustrate, but do not limit, the invention. Parts, ratios and percentages are by weight.

Example: Detailed Method Toner Production Glass transition temperature of 51 ° C, melting point in the range of 65-85 ° C, 13.9
ATLAC T500, a propoxylated bisphenol A fumarate polyester having an acid number of 0.175 dl / g as measured in a mixture of phenol / orthodichlorobenzene (60/40 wt.) At 25 ° C. (Wilmington, USA Atlas Chemical Industries Inc. (trade name) 90
10 parts of carbon black, Cabot Regal400 (trade name of Cabot Corp., Boston, USA)
Heated to 20 ° C to make a melt. At this time, kneading was started. After about 30 minutes, the kneading was stopped and the mixture was cooled to room temperature (20 ° C.), at which point the mixture was crushed and pulverized to form a powder. This was further reduced in particle size by jet milling. Air classification was performed using the above-described apparatus.

Next, the particle size distribution of the toner was measured with a Coulter Multisizer having a 30 μm measuring tube. The results are shown in Table 1 below. Table 1 Diameter (μ) Volume% (Differential) Volume% (Cumulative) 1.00 9.51 100.02 1.26 21.93 90.51 1.59 40.94 68.58 2.00 22.98 27.64 2.62 3.27 4.66 3.18 0.26 1.39 4.01 0.12 1.13 5.05 0.08 1.01 6.36 0.00 0.93 10.09 0.31 0.93 12.71 0.62 0.62 16.01 0.00 0.00 The second column of this table shows the differential percentage of toner particles in the volume located between the isosphere diameters (μ) shown in the first column.

The third column of this table shows the percentage values of the second column on a cumulative basis.

Analysis of the particle size distribution of the toner particles made by the method described above shows the following results: volume percentage of particles greater than 3μ: about 2.5% volume percentage of particles greater than 4μ: about 1% greater than 5μ Volume percentage of certain particles: about 1% The toner particles selected here are introduced into a mixing device, and are mixed at 7 nm.
Mean Aerosil is a fumed hydrophobic silica having a specific surface area of the methanol values and 260 meters ² / g of particles diameter and 56
R812 (trade name of Degussa AG, Germany) was mixed with the toner as follows.

To 100 g of toner particles, 0.5 g of fumed silica particles were added in a metal box (10 cm diameter) containing 100 ceramic balls having an average diameter of 9 mm and a density of 2.4 g / cm ³ . The mixture was then spun at a speed of 300 rpm for 30 minutes (this method is shown in Table 2 as Method A).

Another method that can be used is to add the toner and a flow enhancing additive to a Janke and Kcenkel Labormill apparatus type IKA M20, which is heated at 20 ° C. and rotates at a speed of 20,000 rpm. This machine was developed by Janke and
Available from Kunkel GmbH, IKA Labortechnik. This mixing method of mixing the flow enhancer with the toner is shown in Table 2 as Method B.

Development and transfer electrophotographic recording element (i.e. As ₂ Se ₃ coated conductive drum, which was positively charged and exposed imagewise) was developed by the magnetic brush. This was applied with a developer obtained by mixing a typical carrier of a ferrite carrier (Ni-Zn type) having a magnetization of 50 EMU / g and the obtained toner. The average carrier particle diameter was about 65μ.

After adding the toner particles to the carrier in an amount of 2.5% by weight based on the carrier, the developer was activated by rotating a metal box at a diameter of 6 cm at 300 rpm for 30 minutes, and the apparent filling degree was 30%. .

If the average equivalent toner particle diameter is large, the amount of toner relative to the weight of the carrier should be large; this means in both cases that the amount due to the surface coverage of the toner on the carrier remains equal. I do.

Transfer of electrostatically attached toner is 3kV to metal roll
And the positive voltage was applied. This roll was kept in near ohmic contact with the back side of the paper sheet acting as the receiving material, and the front side of the receiving material was therefore kept in close proximity to the toner image on the photoconductor.

Toner particles transferred according to a fused image are disclosed in U.S. Pat.
It was fed to a radiation melting apparatus operated with an infrared melting element as described in Example 8 of No. 445.

Evaluation of copy quality For example, when using toner particles with a normal particle size distribution characterized by an average particle diameter of 10-15μ, the overall resolution of the electrostatographic method on a normal copier is limited to about 35μ lines This means that line-pair structures where the spacing between successive black lines is less than 35 microns cannot be faithfully reproduced by global electrostatography. However, with the toner according to the invention, lines having a thickness reduced to 25μ could be faithfully reproduced from the original on the final copy.

This was measured as follows: Deutche Forschungsgesellshaft fuer Druck und in Munich, Germany
FOGRA-PMS-System issued by Reproduktinostechnik ev
A wedge according to UGRA-Offset-Testkeil 1982 was copied in an electrostatographic apparatus as described above.

The wedge shows a diagram consisting of concentric circles with increasing resolution. The ultimate resolution on the final copy, which corresponds to the finest concentric circle visually recognizable on the copy made by electrostatic recording as described above, was 25μ.

When the normal optics for illuminating the photoconductive drum was replaced with high quality optics, the ultimate resolution on the final copy was 8μ when using the toner according to the invention.

Measurement of Bulk and Apparent Density and Density Ratio The bulk density of toner particles was determined by Beckman I, Gangy, France.
Measured in the usual manner on an instrument such as the Beckman Air Comparimeter available from nstruments. The details of the measurement and calculation methods of the bulk density is as: i) a first is expressed as the weight (W _t of the amount of toner particles) to accurately measure; ii) Then the toner particles to the Beckman Air Comparimeter Iii) Toner particle volume (V _t is Beckman Air Comperimeter
Is determined by measuring the volume of air eclipsed押退by the toner particles using a; iv) over the weight of the measured toner particles by the method W _t and the ratio W _t / V of the volume V _t of the toner particles _t is the bulk density, denoted as ρbulk.

 The apparent density of the toner particles was measured by the following method.

100 g of toner particles are vibrated in a bottle having a capacity of about 500 ml for a few minutes, then placed on a vibrating sieve having a mesh size of 1 mm and a diameter of 7 cm and vibrating at a frequency of 50 Hz and an amplitude of 1 mm. The stirred toner particles are fed through a sieve into a flat circular receiver having a height of 1.7 cm and a diameter of 7 cm. After equilibrating for 2 minutes, discard the toner particles exceeding the height of the receiver,
The weight of the toner particles contained in the receiver is measured. The apparent density is then calculated as follows.

Example: Evaluation Table 2 below shows the experimental results of the toner prepared by the method described above. According to this, not only the pulverization and classification parameters but also the method of adding the concentration of the flow enhancer were changed.
The resolution of the final copy in the electrostatic recording method using these toners is also shown.

Table 2 below shows the average diameter of the toner particles, the ratio of the bulk density to the apparent density, and the results of the final resolution. The bulk density of the toner particles was 1.17 kg / dm ³ .

The particle size distributions of the toners denoted by reference numerals 1, 2, and 3 satisfy the criteria. The same applies to the filling factor criterion.

The observed resolution is very good. Deviation from the grain size criterion results in a rapid decrease in image quality even if the filling criterion is met.

In Table 2: dv represents the average diameter of the toner particles by volume; dn represents the average diameter of the toner particles by number; d represents (dv x dn) ^1/2 ; In some embodiments, this represents the thickness in μ of the finest line on the original test wedge that was faithfully reproduced on the final copy made with the electrostatic recorder described above; resolution 2 is an electronic record as described above. Μ of the finest line on the current test wedge faithfully reproduced on the final copy made by the instrument
In thickness. However, in this case the usual optical device for illuminating the photoconductive drum is replaced by a high quality optical device; ρapp / ρbulk represents the ratio of the apparent density to the bulk density of the toner particles.

From the above results it is also clear that the resolution obtained with the toner according to the invention is up to 8μ if the irradiation of the photoconductive drum is carried out by means of a high-quality optical device.

The particle size distribution of the toner denoted by reference numeral 2 in Table 2 is shown below. This toner was made by the same method as described above. However, different particle size fractions were obtained by different pulverization and classification settings of the AFG / ATPAlpine combination device described above. Table 3 Diameter volume%, difference volume%, cumulative 1.59 1.13 100.01 2.00 3.44 98.88 2.52 10.34 95.44 3.19 26.97 85.10 4.01 44.79 58.13 5.05 11.52 13.34 6.36 0.39 1.82 8.01 0.29 1.43 10.09 0.19 1.14 12.71 0.19 0.95 16.01 0.00 0.76 20.17 0.76 0.76 25.41 0.00 0.00 The second and third columns have the same meaning as the corresponding columns in Table 1. Analysis of the particle size distribution shows the following results: volume percentage of particles larger than 3μ: 88% volume percentage of particles larger than 4μ: 58% volume percentage of particles larger than 5μ: 15% However, toner particles according to the invention are obtained. Apart from the high resolution, when evaluating the overall technical performance of the individual developer compositions, the various processing characteristics of the electrostatographic method must also be taken into account.

Therefore, the characteristics of the toner composition prepared by the above-described method in the electrostatic recording method were evaluated.

dn, dv, d, ρapp / ρbulk have the same meaning as described above. The method indicates the method A and B used to mix the flow enhancing additive with the toner; the time indicates the time (in seconds) when the flow enhancing additive was mixed with the toner in either method A or B; The weight indicates the weight of the toner in g; the concentration indicates the concentration of the added fumed silica (Aerosil R812).

In Table 4 above, the particle size distribution of the reference numeral 8 is shown below. Table 5 diameter volume%, the difference volume%, total 1.59 3.34 100.00 2.00 5.82 96.66 2.52 11.63 90.84 3.19 21.38 79.21 4.01 28.14 57.83 5.05 20.09 29.69 6.36 7.58 9.60 8.01 2.02 2.02 10.09 0.00 0.00 second column and the third column of Table 1 It has the same meaning as the corresponding column. Analysis of the particle size distribution shows the following results.

Volume percentage of particles larger than 3μ: 82% Volume percentage of particles larger than 4μ: 58% Volume percentage of particles larger than 5μ: 31% The particle size distribution of the toner denoted by reference numeral 13 in Table 4 is shown below. Table 6 diameter volume%, the difference volume%, total 1.59 9.51 100.02 2.00 21.93 90.51 2.52 40.94 68.58 3.19 22.98 27.64 4.01 3.27 4.66 5.05 0.26 1.39 6.36 0.12 1.13 8.01 0.08 1.01 10.09 0.00 0.93 12.71 0.31 0.93 16.01 0.32 0.62 second column and the The three columns have the same meaning as the corresponding columns in Table 1. Analysis of the particle size distribution shows the following results.

Percentage of volume of particles larger than 3μ: 38% Percentage of volume of particles larger than 4μ: 5% Percentage of volume of particles larger than 5μ: 1% In terms of electrostatography, the following points were evaluated: Strongness of toner particles Cleaning problems of the photoconductive drum caused by adhesion, transfer efficiency of toner particles from the photoconductive drum to the paper substrate at the transfer station, fogging on the paper substrate, quality of the magnetic brush and toner to the developing station Overall liquidity and supply.

Among the toner compositions described above, reference numerals 7, 8, 9 and
The toner No. 13 showed good overall performance when viewed in terms of the method characteristics described above. The toner particles of reference numbers 10 and 11 performed poorly for all of the process characteristics described above. On the other hand, the toner composition of reference number 12 showed poor performance in terms of transfer efficiency and quality of the magnetic brush and in terms of cleaning, fogging and toner fluidity.

From the foregoing, it can be concluded that the ratio of bulk density over apparent density is a critical requirement to determine whether a particular toner composition exhibits good overall performance in electrostatography.

Therefore, both the filling specification, expressed as the ratio of the apparent density exceeding the bulk density of the toner particles, and the particle size distribution as the criterion selected for realizing high image quality by dry xerographic toner development, are set. Matching is an essential requirement.

Similar experiments were performed with other silica species exhibiting different specific surface areas and methanol values (shown in the table below). And with toner concentration 2 at a concentration of 2% by weight, app /
Bulk values were measured. This means that satisfying the condition that the product of the specific surface area (Am ² / g) and the methanol value (B% volume) is equal to or greater than 10,000 is one of the conditions stated herein for ρapp / ρbulk. And overall assuring good quality and performance. Table 7 1 2 3 4 5 1 0.18 200 26.5 5300 2 0.26 200 56 11200 3 0.29 300 51.6 15480 4 0.31 380 59.8 22724 5 0.18 130 39.8 5174 6 0.20 200 38 7600 7 0.23 300 36.2 10860 8 0.18 200 0.0 0 9 0.19 200 24.2 4840 10 0.19 200 18.0 3600 11 0.22 200 50.0 10000 12 0.18 200 26.5 5300 13 0.20 170 45.0 7650 14 0.20 300 7.5 2250 Column 1 shows the run number using various flow enhancing additives; Column 2 shows ρapp The third column shows the specific surface area of the flow enhancing additive in m ² / g; the fourth column shows the methanol value of the flow enhancing additive; the fifth column shows the specific surface area. The product multiplied by the methanol value is shown.

From Table 7, the overall realization of the object of the invention, namely the realization of high image quality by dry xerographic toner development, is based on the particle size distribution, the filling criterion expressed as a ratio of the apparent density exceeding the bulk density of the toner particles (the density of such a density). Realization is the result of using flow improving additives that meet strict criteria for the product of the specific surface area and the methanol value).

────────────────────────────────────────────────── (7) Continuation of the front page (72) Inventor Van Kouvenberg, Hans Karl Belgium, 2610 Wilrijk, Priel Strat 35 (56) References JP-A-62-52567 (JP, A) JP-A-62 -269150 (JP, A) JP-A-63-123056 (JP, A) JP-A-62-147651 (JP, A) JP-A-63-139367 (JP, A) JP-A-61-241766 (JP, A) JP-A-60-238847 (JP, A) JP-A-62-293253 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08

Claims (11)

(57) [Claims] 1. A dry electrostatic recording toner particle suitable for use in developing an electrostatic charge pattern, wherein said toner particle comprises: (I) 90% by volume or more of the toner particle is larger than 0.5.
(II) characterized by a classified particle size distribution in which at least about 50% by volume or more of the toner particles have a particle size diameter of less than about 5μ; (III) the toner particles have at least 0.1% by weight and at most 5% by weight of fine inorganic fine particles acting as a flow enhancing additive at a concentration of 5% by weight, wherein the fine inorganic fine particles satisfy the following relationship: A × B> 10000 Specific surface area (A) (m ² / g) to methanol value (B)
(Volume%) as a characteristic, whereby the ratio of the apparent density to the bulk density of the toner particles is calculated by the following equation: Dry electrostatic recording toner particles, characterized by satisfying the following. 2. The method of claim 1 wherein at least 90% by volume of the toner particles have a particle size diameter greater than 0.5μ and less than 6μ, and at least about 50% by volume of the toner particles have a particle size diameter less than about 4μ. The dry electrostatic recording toner particles according to the above. 3. The method of claim 1, wherein at least 90% by volume of the toner particles have a particle size diameter greater than 0.5μ and less than 5μ, and at least about 50% by volume of the toner particles have a particle size diameter less than about 3μ. The dry electrostatic recording toner particles according to the above. 4. The dry electrostatic recording toner particle according to claim 1, wherein the fine inorganic fine particles are coated with a hydrophobic group-containing unit to produce a methanol value greater than 20. 5. The dry electrostatic recording toner particles according to claim 1, wherein the fine inorganic fine particles have a specific surface area of more than 150 m ² / g. 6. The dry electrostatic recording toner particles according to claim 1, wherein the fine inorganic fine particles are fumed inorganic substances. 7. The method of claim 1, wherein the fumed silica is present in an amount of at least 0.5% by weight based on the weight of the toner.
7. The dry electrostatic recording toner particles according to claim 6. 8. The dry electrostatic recording toner particles according to claim 1, further comprising a colorant dispersed or dissolved in the toner binder resin. 9. The dry electrostatic recording toner particles according to claim 6, wherein said fumed inorganic substance is fumed dredica. 10. The dry electrostatic recording toner particles according to claim 1, wherein the toner particles contain a negative or positive charge control agent. 11. A dry electrostatographic toner as claimed in claim 1, wherein the toner particles are mixed with carrier particles for cascade of electrostatic charge patterns or magnetic brush development. particle.