JPS5911103B2 - Electrostatographic toner material and electrostatographic developer composition containing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates generally to electrostatographic imaging systems, and more particularly to improved developer materials and uses thereof.

30 Methods of forming and developing images on the surface of photoconductive materials by electrostatic means are well known.

C.F. Carlson
As taught in U.S. Pat. Dissipating the charge on the area of the layer, and to those skilled in the art '
It involves developing an electrostatic latent image created by depositing a finely divided electroscopic material called a "toner" onto the image. , thereby forming a toner image corresponding to the electrostatic latent image. This powder image can then be transferred to a support surface, such as paper. Instead of uniformly charging the photoconductive layer and then exposing this layer to the document, a latent image may be formed by directly charging the photoconductive layer. If it is desired to omit the powder image transfer step, the powder image can be fixed to the photoconductive layer. Other suitable fixing means such as a solvent or coating process can be used in place of the heat fixing step. Many methods are known for applying electroscopic particles to an electrostatic latent image to be developed.

One development method is known as 11 cascade one development, as described in US Pat. No. 2,618,553 to EN Wise.

In this method, a developer mixture containing relatively large carrier particles with fine toner particles electrostatically adhering to the surface of the carrier particles is moved and rolled or cascaded to the electrostatic latent image bearing surface. The composition of the toner particles is selected to have a triboelectric polarity opposite that of the carrier particles. To develop a negatively charged electrostatic latent image, an electroscopic powder and carrier combination should be selected in which the powder is triboelectrically positive with respect to the carrier. Conversely, to develop a positively charged electrostatic latent image, electroscopic powders and carriers should be selected that are triboelectrically negative with respect to the carrier. The triboelectric relationship between the powder and the carrier depends on their relative positions in the triboelectric series, where each material is positively charged when it comes into contact with a lower material in the series;
and the materials are arranged in such a way that they become negatively charged when they come into contact with further materials in the row. As this mixture cascades or rolls across the image-bearing surface, toner particles are electrostatically deposited and fixed onto the charged portions of the latent image and are not deposited onto the uncharged or background portions of the image. Most of the toner particles accidentally deposited in the background are apparently due to the greater electrostatic attraction between the toner and the carrier than between the toner and the discharged background.
Removed by rolling carrier. The carrier particles and unused toner particles are then recycled. This technique is very good for developing line copy images. This cascade development process is the most widely used commercial electrostatographic development technique. A general office copier incorporating this technology is described in US Patent No. 3,099,943.

Other techniques for developing electrostatic images are described, for example, in US Pat.
11 magnetic brush 1 method as described in 874063.

In this method, a developer material containing toner and magnetic carrier particles is held by a magnet. The magnetic field of this magnet causes alignment of the magnetic carriers in a brush-like arrangement. This 11
A magnetic brush 11 is brought into contact with the electrostatic latent image and toner particles are drawn from the brush to the electrostatic image by electrostatic attraction. C.R. May U.S. Patent Black No. 28958
As stated in 47! 5 touch down (TOuch
Many other methods are known for applying electroscopic particles to the electrostatic latent image to be developed, such as dOwn)1 development. The above-described development methods, along with many variations, are well known to those skilled in the art through various patent publications and through the widespread availability and use of electrostatographic imaging equipment. Automatic electrostatographic equipment commonly uses an electrostatographic plate in the form of a cylindrical drum that rotates through a cycle of continuous operations including charging, exposing, developing, transferring, and cleaning. This plate was created by L.W. Walkatup.
It is normally charged with a corona of positive polarity by a corona generating device connected to a suitable high voltage power source of the type described in U.S. Pat. After forming a powder image on the electrostatic image during the development step, the powder image is electrostatically transferred to the support surface by a corona generating device, such as the corona device described above. In automatic equipment using a rotating drum, the support surface to which the powder image is to be transferred is moved through the equipment at the same speed as the periphery of the drum, and the drum is moved at a transfer position provided between the drum surface and the corona generator. come into contact with. Transfer is accomplished by a corona generator that applies an electrostatic charge to attract the powder image from the drum to the surface of the support. The polarity of the charge required to effect image transfer depends on the visibility of the original copy to the reproduction and the electrostatic properties of the developing material used to effect the development. For example, when a positive reproduction is made from a positive original, it is common to use a positively polarized corona to effect the transfer of the negatively charged toner image to the surface of the support. If a positive reproduction is desired from a negative original, a positively charged developer is driven by a charged area on the plate into a discharge area to form a positive image which can be transferred by a negatively polarized corona. It is common to use materials. In either case, residual powder images and sometimes carrier particles remain on the plate after transfer. Before this plate is reused for the next cycle, remaining images and carrier particles, if any, need to be removed to prevent ghost images from forming in the next cycle. . In the positive-to-positive replication process described above, residual developer powder as well as any carrier particles present are fixed on the plate surface by a development that is not well understood but is believed to be caused by charge. This charge is substantially neutralized by the device and the corona generating device prior to contacting the remaining powder. Neutralization of the charge increases the cleaning effectiveness of the cleaning device.
A typical electrostatographic cleaning device is, for example, a double.
1, as described in U.S. Pat. No. 3,186,838 by W. P. Graff Jr. et al.
This is a web 71 type cleaning device.

In the Graf-Giunier et al. patent, removal of residual powder and carrier particles on the plate is accomplished by rubbing a web of fibrous material against the imaging plate surface. These inexpensive and replaceable webs of fibrous material are forced and rubbed or wiped into contact with the imaging element surface and are gradually advanced to provide a clean surface to the plate, thereby removing the material from the plate. Substantially complete removal of residual powder and carrier particles occurs. While typically producing images of good quality, conventional development systems suffer from serious deficiencies in certain areas. When reproducing high contrast copies such as text, tracing, etc.
It is desirable to select such electroscopic powders and carrier materials because their mutual charges are in most cases governed by the distance between their relative positions in the triboelectric series. However, also when the electroscopic powder and carrier material are separated from each other in the triboelectric train by too large a distance, the image produced is very faint, due to the attractive forces between the carrier and the toner particles. is comparable to the attractive force between the electrostatic latent image and the toner particles. Although the image density described in the above text can be improved by increasing the toner concentration in the developer mixture, when the toner concentration in the developer mixture is excessive, an undesirably high background toner concentration can occur. Sedimentation and increased toner sticking and clumping occur. Although the initial electrostatographic plate charge can be increased to improve the density of the deposited powder image, this plate charge would normally have to be excessively high to attract the electroscopic powder from the carrier particles. . Not only is an excessively high electrostatographic plate charge undesirable because of the high power consumption required to maintain the electrostatographic plate at a high potential, but high potentials also cause carrier particles to exceed the electrostatographic plate surface. This is also to cause it to adhere to the electrostatographic plate surface rather than simply rolling away. When carrier particles adhere to a reusable imaging surface, print defects and bulk carryover of carrier particles often occur. Clumpy Carrier The problem of carry-over is particularly evident when the developer is used in machines that tend to reproduce surface images, where an excess amount of toner particles is removed from the carrier particles, so that they contain almost no toner particles. Leaves many carrier particles behind. Additionally, adhesion of carrier particles to reusable electrostatographic imaging surfaces promotes the formation of undesirable marks on the surface during image transfer and surface cleaning operations. It is therefore clear that many materials which would otherwise have properties suitable for use as developer materials are unsuitable because they have unsatisfactory triboelectric properties. Furthermore, uniform triboelectric surface properties of many carrier surfaces are difficult to obtain in mass production systems. When non-uniform triboelectric properties are used,
Good quality images are almost difficult to obtain with high speed automatic machines. Although it is possible to change the triboelectric value of an insulating carrier material by incorporating into the carrier material another insulating material that has a triboelectric value significantly different from that of the original carrier material, A relatively large amount of additional material is required to change the triboelectric value of the carrier material.
The addition of large amounts of material to the original carrier material to change its triboelectric properties requires extensive manufacturing operations and often undesirably changes the original physical properties of the carrier material. It is therefore highly desirable to adjust the triboelectric properties of the carrier surface to suit the desired toner composition use while preserving other desirable physical properties of the carrier. Another factor that affects the stability of the triboelectric properties of a developer material is the ease with which the developer particles adhere to toner. When a developer mixture is used in an automatic machine and circulated through many cycles, the many collisions that occur between the carrier particles and other surfaces in the machine cause the toner particles to be carried onto the surface of the carrier particles and remain in close contact. or cause it to be forced onto another carrier particle. Gradual deposition of toner material deposited on the surface of the carrier causes changes in the triboelectric value of the carrier and directly contributes to deterioration of copy quality by destroying the toner carrying capacity of the carrier. Thus, the need for good developer materials for developing electrostatic latent images continues. It is therefore an object of the present invention to provide a developing material which overcomes the above-mentioned deficiencies.

Another object of the invention is to provide a developer material that is less agglomerated and has improved dispensing properties.

Yet another object of the invention is to provide a developing material having more stable electrostatographic properties.

Yet another object of the present invention is to provide a developer material having a longer developer life.

Yet another object of the present invention is to provide a developer material that is less susceptible to toner sticking.

Yet another object of the present invention is to provide a developing material that is more resistant to film formation on electrostatographic recording surfaces.

Another object of the present invention is to provide a developer material that exhibits improved electrical and mechanical properties useful in electrostatographic devices using magnetic brush development devices.

Yet another object of the present invention is to provide a developer material having physical and chemical properties superior to those of known developers. The foregoing objects are generally achieved by providing an electrostatographic developer material comprising a classified toner material that electrostatically charges the surface of a carrier material having a classified charging surface, wherein The classified toner material has a particle size volume distribution having a Fine Index ratio of about 2.50 or less, a Coarse Index ratio of about 1.50 or less, and a particle size volume distribution of about Up to 30% of the toner particles have an average particle diameter of about 5 microns or less, about 25% of the particles have a diameter of about 8 to about 12 microns, and up to about 5% of the toner particles have an average particle diameter of about 20 microns or more. The classified high surface area carrier material has a specific surface area of at least about 150 crA/7.

However, the carrier material should be at least about 165 cd/
It is preferred to have a specific surface area of 7.7 because the developer life is such that it provides excellent copy quality with the developer material in high speed electrostatographic reproduction equipment, and also has a low background level and constant surface area. This is because it has been improved to maintain the development density. The carrier material of the invention is at least about 17
Optimum results are obtained with a specific surface area of 5cr1i/y. The area ratio of carrier to toner material, or toner concentration, in a high-speed magnetic brush development system is such that the background of the electrostatic latent image during development must be maintained to maintain sufficient toner concentration to provide a satisfactory areal image. Such that sufficient charge levels cannot be maintained to minimize deposition of toner material in the area.

This problem has been overcome by providing the carrier material of the present invention with minimal specific surface area. Thus, the present invention now allows the use of developer mixtures having lower toner concentrations per carrier surface area to provide higher net charge levels. In electrostatographic processes in which a carrier material is used to provide a triboelectric charge to the toner material by contact charge transfer, the area of the carrier triboelectric charging surface has been found to be of critical importance. It has been found that the carrier charging surface area is related to the amount of toner material that can be charged to a useful tribopotential for a given toner material. Therefore, in accordance with the present invention, it has been found that the triboelectric charging performance of the carrier material is dependent on the surface area. Thus, the present invention can be used to design the optimal carrier material for any given electrostatographic development system. The term coarseness index is defined as the ratio of the volume distribution of the particle diameter of 84% of the toner particles divided by the particle diameter of 50% of the toner particles.

Similarly, the term microindex is defined as the ratio of the particle diameter number distribution of 50% toner particles divided by the particle diameter of 16% toner particles. Both the coarse index and fine index ratios are calculated from volume and number cumulative frequency plots obtained from particle size analysis performed on a Coulter counter using a 100 micron orifice.
The coarseness index represents the median or average particle size distribution by weight or volume of the toner particles and has a significant influence on the copy quality obtained in an electrostatographic development system. The fineness index is a measurement of the number average distribution of toner particles, weighed on the fine side, and is a measure of the useful life of the developer, the life of the system, the rate of film formation on the photosensitive material, and the toner on the electrostatographic recording surface. has an important influence on measurements of adhesion. The particle size number distribution minute index of toner particles is approximately 2.
5 or less, the classified developer materials of the present invention have been found to provide satisfactory results.

Improved results are obtained with particle size distribution micro-indexes of less than or equal to about 2.00, which are preferred. Optimal results are obtained when the particle size distribution micro-index of the classified toner material is about 1.45 or less.
Similarly, satisfactory results are obtained with the classified developer materials of the present invention when the particle size volume distribution coarsening index of the toner particles is less than or equal to about 1.50. However, it is preferred that the particle size volume distribution coarsening index be less than or equal to about 1.45 because improved resolution and sharpness will be obtained in copies. Optimal results are obtained when the particle size volume distribution coarseness index of the toner material is about 1.35 or less. Further, the particle size distribution is such that several percentages of toner particles have an average particle diameter of about 30% or less about 5 microns or less, and several percentages of about 25.0% toner particles have an average particle diameter of about 8 to about 12 microns. The classified toner materials of the present invention provide satisfactory results when the toner particles have an average particle diameter of about 20 microns or more, and a few percentages of the toner particles have an average particle diameter of about 20 microns or more. It has been found.

However, the particle size distribution is such that up to a few percentage points, about 20% of the toner particles have an average particle diameter of about 5 microns or less, and about 45% of the toner particles have an average particle diameter of about 8 to about 12 microns. , and it is preferred that up to a percentage of about 5.0% of the toner particles have an average particle diameter of about 20 microns or greater. The particle size distribution is such that up to a few percentages of about 10% of the toner particles have an average particle diameter of about 5 microns or less and a few percentages of about 60% of the toner particles have an average particle diameter of about 8 to about 12 microns. , and a few percent of toner particles less than about 5% are about 20 microns 7
Optimal results are obtained when the average particle diameter is greater than or equal to the average particle diameter. It has been found that the classified carrier materials of the present invention provide satisfactory results when the particle size volume distribution geometric standard deviation is less than or equal to about 1.3 and the volume average particle diameter is less than or equal to about 100 microns. Improved results are obtained and are preferred when the particle size volume distribution geometric standard deviation is less than or equal to about 1.2 and the volume average particle diameter is less than or equal to about 90 microns. Optimal results are obtained when the volume distribution geometric standard deviation of the classified carrier materials of the present invention is less than or equal to about 1.15 and the volume average particle diameter is less than or equal to about 85 microns. As used herein, the term geometric standard deviation is defined as the deviation produced in a particle size analysis approximately measured as the ratio of the particle diameter larger than 84% of a sample to that of the particle diameter larger than that of 50% of the sample. Ru. This number represents the median or average particle size distribution by weight or volume of the carrier particles and has a significant influence on the quality of copies obtained in electrostatographic development systems. Another measure of the geometric standard deviation of the classified carrier materials of the present invention was approximately determined as the ratio of the larger particle diameter of 50% of the samples to that of the larger 16% of the samples (!) This is the deviation that occurred in particle size analysis. This 50
The % figure represents the medium or average particle size by volume of the carrier particles and has a significant impact on determining the useful life of the developer. In both cases, the values obtained for the volume average particle diameter and geometric standard deviation are determined by dimensional analysis performed by sieve distribution using all US standard sieves from 325 to 70 mesh. Any suitable classification method may be used to obtain the classified toner materials of the present invention.

Typical particle classification methods include air classification, screening, cyclone separation, elutriation, centrifugation, and combinations thereof. A preferred method of obtaining the classified toner material of the present invention is by centrifugal air classification. In this method, air or some other gas flows through a flat, cylindrical chamber into a spiral passage. Particles in an air stream are subject to two opposing forces,
That is, it is exposed to the inward traction force of air and the outward centrifugal force of particles. For the exact size of the particle, ie, one cut size, both forces are balanced. Larger (heavier) particles are dominated by centrifugal forces that depend on their mass, and smaller (lighter) particles are dominated by frictional forces that are proportional to the particle diameter. As a result, large or heavy particles fly outward as coarse fractions, while small or light particles are carried inward as fine fractions. 11 The cut size 11 usually depends on the helical slope, the circumferential slope and the absolute dimensions of the classification chamber.

The adjustment of 1 cut size 1 is done through the variation of the two factors mentioned at the beginning, while! The range of one cut size 11 can be determined by the respective dimensions of the classification chamber.

Satisfactory centrifugal air classification results were obtained using MikrOplex, commercially available from Alpine American Corporation, Nachizuku, Masachi, Japan.
) (Product name) Spiral air classifier type 132M
This can be obtained when using equipment such as the Model P or Accut(TM) Model Bl8 units available from The Donaldson Company, Tulsa Oklahoma. Any suitable particle classification method may be used to obtain the high surface area carrier materials of the present invention.

Typical particle classification methods include air classification, screening, cyclone separation, water, centrifugation, and combinations thereof. A preferred method of obtaining the high surface area carrier material of the present invention is by screening or sieving. at least about 110'
Any suitable vinyl resin having a melting point of F can be used in the toner composition. The vinyl resin is a homopolymer or a copolymer of two or more vinyl monomers.
Typical monomer units that may be used to form vinyl polymers are: styrene, P-chlorostyrene, vinylnaphthalene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene, etc.; vinyl esters, For example, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Esters of α-methylene aliphatic monocarboxylic acids, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, Isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, etc.; acrylonitrile, methacrylonitrile, acrylamide, vinyl ether, e.g. vinyl Methyl ether, vinyl isobutyl ether, vinyl ethyl ether, etc.; vinyl ketones, such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone, etc.; vinylidene halides, such as vinylidene chloride, vinylidene chlorofluoride, etc.; and N-vinyl compounds, such as N −
Includes vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone, and mixtures thereof. Generally, preferred vinyl resins used in toners have a weight average molecular weight of about 3,000 to about 500,000. Toner resins containing relatively high percentages of styrene resin are preferred. The presence of styrene resin is preferred since better resolution is generally obtained during latent image development. Additionally, denser images are obtained when at least about 25 weight percent styrene resin is present in the toner, based on the total weight of resin in the toner. The styrenic resins are homopolymers of styrene or styrene analogs or copolymers of styrene with other monomer groups containing a single methylene group attached to a carbon atom by a double bond. Thus, typical monomeric materials that can be copolymerized with styrene by addition polymerization are: p-chlorostyrene, vinylnaphthalene, ethylenically unsaturated monoolefins, such as ethylene, propylene, butylene, isobutylene, etc.; vinyl esters, such as vinyl chloride. , vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc.; esters of α-methylene aliphatic monocarboxylic acids, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, Dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-alpha
-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, etc.; acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers, such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, etc.; vinyl ketones, such as vinyl methyl ketone, vinyl hexyl ketone, Methyl isopropenyl ketone, etc.; vinylidene halides, such as vinylidene chloride, vinylidene chlorofluoride, etc., and n-vinyl compounds, such as N-vinylpyrrole,
N-vinylcarbazole, N-vinylindole, N-
and mixtures thereof. Styrenic resins can also be formed by the polymerization of styrenic monomers and mixtures of two or more of these unsaturated monomeric materials. The expression 1' addition polymerization 1 includes known polymerization techniques such as free radical, anionic and cationic polymerization techniques. Vinyl resins, including styrenic type resins, may be blended with one or more other resins as desired.

When vinyl resins are blended with other resins, the added resin is preferably another vinyl resin, because the resulting blend has particularly good triboelectric stability and uniform resistance to physical degradation. This is because it is characterized by Vinyl resins used for compounding with styrenic or other vinyl resins may be prepared by addition polymerization of any suitable vinyl monomers, such as those described above. Other thermoplastic resins may also be blended with the vinyl resins of the present invention. Representative non-vinyl thermoplastic resins include: rosin-modified phenol formaldehyde resins, oil-modified epoxy resins, polyurethane resins, cellulosic resins, polyether resins, and mixtures thereof. When the resin component of the toner contains a blend of styrene or polystyrene copolymerized with other unsaturated monomers and other resins, at least about 25% by weight based on the total weight of resin present in the toner. The styrene component is preferred because it provides denser images and provides better resolution for a given amount of toner material. Although the specific formula given for the units contained in the resin of the toner material represents the majority of units present,
It goes without saying that the presence of monomeric units or reactants other than those indicated is not excluded.

For example, some commercially available materials contain trace amounts of congeners or unreacted or partially reacted monomers. Small amounts of this substituent may be present in the materials of the invention. Any suitable pigment or dye may be used as a colorant for the toner particles.

Toner colorants are well known and include, for example, carbon black, nigrosine dye, aniline blue, calcooil blue chrome yellow, ultramarine blue, DuPont oil red, quinioline yellow, ethylene blue chloride, phthalocyanine blue, malachite green oxalate. , lampblack, rose bengal and mixtures thereof. The pigment or dye should be present in the toner in an amount sufficient to render it highly pigmented so that it forms a clearly visible image on the recording member. Thus, for example, if a conventional electrostatographic copy of a typed document is desired, the toner may be a black pigment such as carbon black, e.g.
or channel black or black dyes, such as Amaplast Black dye commercially available from National Aniline Products. Generally, pigments are used in amounts of about 1 to about 20% by weight, based on the total weight of the pigmented toner. If the toner colorant used is a dye, substantially less colorant may be used. However, since many of the pigments used in electrostatographic toner compositions affect the glass transition and melting temperature of the toner compositions of the present invention, their concentration should preferably be about 10% by weight of the pigmented toner. It is. Toner compositions may be manufactured by well-known toner mixing and grinding techniques. For example, the ingredients can be thoroughly mixed by blending, mixing and grinding the ingredients, and then micronizing the resulting mixture. Another well known technique for forming toner particles is spray drying a ball milled toner composition containing a colorant, resin, and solvent. Any suitable coated or uncoated electrostatographic carrier bead material can be used as the high surface area carrier material of the present invention.

Typical cascade development method carriers are sodium chloride,
Contains ammonium chloride, potassium aluminum chloride, Rothsiel salt, sodium nitrate, aluminum nitrate, potassium chlorate, granular zircon, granular silicon, methyl methacrylate, glass and silicon dioxide. Typical magnetic brush development carriers include nickel, steel, iron, ferrite, and the like. This carrier can be used with or without a coating. Many of the above and other representative carriers are
U.S. Patent No. 2,638,416 to L.E. Wallcup et al. and E.N.
．． Wise) in US Pat. No. 2,618,552. A final coated carrier particle feed diameter of about 30 to about 1000 microns is preferred because the carrier particles then have sufficient density and inertia to avoid adhesion to the electrostatic image during the cascade development process. For magnetic brush development, the carrier particles generally range from about 30 to about 250
It has an average diameter of microns. Generally speaking, satisfactory results are obtained when about 1 part toner is used with about 10 to 200 parts by weight of carrier. The high-area carrier materials of the present invention may be coated with any suitable coating material.

Typical electrostatographic carrier particle coating materials include vinyl chloride monoacetate copolymers, styrene-acrylate organosilicone polymers, natural resins such as cyanide, colophonium, kobal, damar, dragon's plat, jarlap, and stratus; polyolefins. thermoplastic resins, such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene, polyvinyl and polyvinylidene, such as polystyrene, polymethylstyrene, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, poly vinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; fluorocarbons such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyamides such as polycaprolactam and polyhexamethylene adipamide; polyester, For example, polyethylene terephthalate polyurethane; polysulfide, polycarbonate; thermosetting resins including phenolic resins, such as phenol formaldehyde, phenol-furfural and resorcinol formaldehyde; amino resins, such as urea-formaldehyde and melamine formaldehyde; polyester resins; epoxy resins, etc. include. Many of these and other representative carrier coating materials are described in U.S. Pat. No. 2,618,551 to L. I. Workup; - Described in U.S. Patent No. 3,533,835 and Black, No. 3,658,500 by R. J. Hagenbach et al. Any suitable electrostatographic coating thickness may be used when coating the high surface area carrier materials of the present invention.

However, carrier coatings that are at least thick enough to form a thin continuous film over the carrier particles are preferred because the carrier coating then resists wear and the triboelectric properties of the coated carrier particles. This is because the thickness is sufficient to prevent pinholes that would adversely affect the surface of the substrate. Generally, for cascade and magnetic brush development, the carrier coating may contain from about 0.1 to about 10.0 weight percent, based on the weight of the coated carrier particles. Preferably, the carrier coating should contain from about 0.3 to about 1.5 weight percent, based on the weight of the coated carrier particles, for maximum durability, toner stick resistance, and copy quality. This is because it will be done. Well-known additives such as plasticizers, reactive and non-reactive polymers, dyes, pigments, wetting agents and mixtures thereof can be mixed with the coating material to further modify the properties of the coated composite carrier particles. . When coated with the high surface area carrier material of the present invention, the carrier coating composition can be applied to the carrier core by any conventional method, such as spraying, dipping, fluid bed coating, rolling, brushing, and the like.

The coating composition can be applied as a powder, dispersion, solution, emulsion or hotmelt. When applied as a solution, any suitable solvent may be used. Solvents with relatively low boiling points are preferred because less energy and time are required to remove the solvent following application of the coating to the carrier. If desired, the coating may include monomers that are polymerized in situ on the surface of the core or plastisol that is gelled in situ to a non-flowing state on the surface of the core. Surprisingly, it has been found that carrier core materials having the specific surface areas selected in this invention yield increased effective area or triboelectrically charged area per unit weight compared to certain poor coating methods. Thus, the increased carrier active area increases the net toner material tribocharge level for a constant toner concentration by weight in the developer mixture. Therefore, the concentration of toner is minimal to provide a sufficient surface image, and high enough to minimize toner deposition on the background of the developed electrostatic latent image produced from toner particles with low or weak triboelectric charges. If it is preferred to operate the electrostatographic development system at toner concentration,
These objectives can be achieved by using the high surface area carrier materials of the present invention. In accordance with the present invention, the above objects are achieved by operating at reduced toner concentrations that provide less background deposits and allow longer developer life. Any suitable organic or inorganic photoconductive material can be used as a recording surface with the classified developer materials of this invention.

Typical inorganic photoconductor materials are: sulfur, selenium, zinc sulfide, zinc oxide, zinc cadmium disulfide, zinc magnesium oxide, cadmium selenide, zinc silicate, calcium strontium sulfide, cadmium sulfide, mercury iodide, mercury oxide. , mercury sulfide, indium trisulfide, gallium selenide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, antimony trisulfide, cadmium sulfo-selenide, and mixtures thereof. Typical organic photoconductors are: quinacridone pigments, phthalocyanine pigments, triphenylamine, 2.
4-vitx (4・l-diethylaminophenol)
-1,3,4-oxadiazole, N-isopropylcarbazole, triphenylpyrrole, 4●5-diphenylimidazolidinone, 4,5-diphenylimidazolydinethione, 4,5-vitx ( 4'-aminophenyl)-imidazolidinone, 1,5-dicyanonaphthalene, 1,4-dicyanonaphthalene, aminophthalodinitrile, nitrophthalodinitrile, 1,2,5,6
-tetraazocyclooctatetraene (2, 4, 6,
8), 2-mercaptobenzothiazole-2-phenyl-4-disphenylideneoxazolone, 6-hydroxy-2,3-di(p-methoxyphenyl)-benzofuran, 4-dimethylamino-benzylidene-benzhydrazide, 3-benzylidene-aminocarbazole polyvinylcarbazole, (2-nitro-benzylidene)-p-bromoaniline, 2,4-diphenylquinazoline, 1,2
- Contains 4-triazine, 5-diphenyl-3-methyl-pyrazoline, 2-(4'dimethylaminophenyl)-benzoxazole, 3-aminocarbazole, and mixtures thereof. A typical patent describing photoconductive materials is Ullrich U.S. Patent No. 28035.
42, Bixby US Patent Black 2970
906, Middleton (MiddletOn) US Pat. No. 3,121,006, Middleton (MiddletOn)
U.S. Patent No. 3,121,007 and Corsin (COrrs)
Including U.S. Pat. No. 3,151,982 in)

The following examples further clarify, describe and compare methods of making the developer materials of the present invention and utilizing them to develop electrostatic latent images.

Parts and percentages are by weight unless otherwise specified. In the examples below, toner adhesion is measured by spectrophotometric techniques.

Typically, 357 samples of developer mixture are accurately weighed. This is then washed with an aqueous surfactant solution to remove any loose, non-fixed toner. A quantity of a suitable solvent is added for the purpose of dissolving the fixed toner polymer and suspending the carbon black. Ultrasound is applied to the mixture of solution and suspended carbon black to disperse the carbon black. The resulting suspension is transferred to a volumetric flask and diluted to the mark with additional solvent. The apparent absorption of the suspension is measured in the visible range. This is compared to a standard curve obtained from virgin toner used in the developer. The concentration of fixed toner is calculated from the absorption of the sample dispersion. In general, it has been found that what mechanical tests are most useful for measuring toner adhesion rates.
Due to practical considerations, the number of measurements should be limited and very good results calculated from toner adhesion during the first 50,000 copies of any test were obtained. The toner sticking rate is calculated from the amount of toner stuck per 7 of developer per 1000 copies. Additionally, in the examples below, the toner materials are classified using an Accut(TM) Model Bl8 unit commercially available from Donaldson Company, Inc., Tulsa, Oklahoma.

Example 1 About 58.0% by weight styrene and about 42.0% by weight n-
A control developer mixture is prepared by mixing a toner composition comprising a mixture of about 90 parts by weight of a copolymer of Butyk methacrylate and about 10 parts by weight of furnace carbon black with carrier particles.

The toner particles are measured to have a particle size distribution fine index of about 1.70, a particle size volume distribution coarseness index of about 1.40, and about 50% of the toner particles have an average particle diameter of about 5 microns or less, and A percentage of the particles, about 23%, have an average particle diameter of about 5 to about 8 microns, and a percentage of the toner particles, about 15%, have an average particle diameter of about 8 to about 1 micron.
A percentage of the toner particles, about 7%, have an average particle diameter of about 12 to about 20 microns, and a percentage of the toner particles, about 5%, have an average particle diameter of about 20 microns.
It had a particle size distribution with an average particle diameter of microns or more. Approximately 0.6% by weight, based on the weight of the core material, including styrene, methacrylate esters and organosilicon compounds as described in U.S. Patent No. 3,526,533
The carrier particles include nickel-zinc ferrite coated with a carrier coating composition. This coated ferrite carrier material has a particle size distribution determined by sieve analysis as follows: By calculation, the coated ferrite carrier material has a specific surface area of approximately 128 d/f.

About 1 part by weight of toner particles is mixed with about 100 parts by weight of carrier particles to form a developer mixture. Copies of standard test patterns were made using this developer mixture in an electrophotographic copier using a magnetic brush development system. It was found that after about 100,000 copies this developer mixture deteriorated. Developer deterioration manifests itself in the form of high backlogs.

That is, the specified background density of 0.01 is exceeded at 1.0 plane image density. High levels of film formation on the photosensitive material occurred approximately every 15,000 copy intervals and were observed as printouts on the copies. Toner sticking rate is approximately 0
．． It turned out to be 0450. EXAMPLES A developer mixture is prepared by mixing about 1 part of the donor material used in Example 1 with about 100 parts of the carrier material used in Example I, except that the toner particles are measured to be about 2.5 parts. Particle size number distribution minute index of 07, approximately 1.
a particle size volume distribution coarse index of 40, and about 29% of the toner particles have an average particle diameter of about 5 microns or less;
A percentage of the toner particles, about 30%, have an average particle diameter of about 5 to about 8 microns; a percentage of the toner particles, about 25%, have an average particle diameter of about 8 to about 12 microns; A percentage of the toner particles, about 11%, had an average particle diameter of about 12 to about 20 microns, and a percentage of the toner particles, about 5%, had a particle size distribution of about 20 microns or more.

This carrier material had the following particle size distribution as determined by sieve analysis: Calculations show that the coated ferrite carrier material is about 151 ct! It has a specific surface area of i/f.

A developer is used under the same conditions as in Example 1 to develop the electrostatic latent image. This developer mixture was found to perform satisfactorily up to about 225,000 copies. Low levels of film formation on the photosensitive material were observed as printouts on copies at a frequency of approximately 25,000 copy intervals. The toner adhesion percentage was found to be approximately 0.0280. EXAMPLE A developer mixture is prepared by mixing about 1 part of the toner material used in Example 1 with about 100 parts of the carrier material used in Example I, except that the toner particles are measured to be about 2 Particle size distribution micro index of .60, approx.
a particle size volume distribution coarseness index of 35, and about 23% of the toner particles have an average particle diameter of about 5 microns or less;
A percentage of the toner particles, about 18%, have an average particle diameter of about 5 to about 8 microns; a percentage of the toner particles, about 35%, have an average particle diameter of about 8 to about 12 microns; The toner particles had a particle size distribution in which a percentage of the toner particles, about 19%, had an average particle diameter of about 12 to about 20 microns, and a percentage of the toner particles, about 5%, had an average particle diameter of 20 microns or more.

This carrier material had the following particle size distribution as determined by sieve analysis: According to calculations, the coated ferrite carrier material has a specific surface area of approximately 160 cd/y.

A developer is used under the same conditions as in Example 1 to develop the electrostatic latent image. This developer mixture was found to perform satisfactorily up to about 375,000 copies. Low levels of film formation on the photosensitive material were observed as printouts on the copies at a frequency of approximately every 35,000 copies. The toner adhesion percentage was found to be approximately 0.0220. EXAMPLE A developer mixture is prepared by mixing 1 part of the toner material used in Example 1 with about 100 parts of the carrier material used in Example 1, except that the toner particles are measured at about 2.25 parts. Particle size distribution micro index of approximately 1.35
particle size volume distribution coarseness index, and about 21% of the toner particles have an average particle diameter of about 5 microns or less, and a percentage of the toner particles about 15% have an average particle diameter of about 5 to about 8 microns. , about 40 percent of toner particles
% have an average particle diameter of about 8 to about 12 microns;
About 19% of the toner particles are about 12 to about 20
It had a particle size distribution with an average particle diameter of microns and a few percentages of the toner particles, about 5%, having an average particle diameter of 20 microns or more.

This carrier material had the following particle size distribution as determined by sieve analysis: According to calculations, the coated ferrite carrier material has a specific surface area of approximately 168 cd/y.

A developer is used under substantially the same conditions as in Example 1 to develop the electrostatic latent image.

When the test was stopped, this developer mixture was at 32,500
It has been found that the process can be performed satisfactorily up to 0 copies. Low levels of film formation on the photosensitive material were observed as printouts on copies approximately every 50,000 copy intervals.
The toner adhesion percentage was found to be approximately 0.0140. Example v A developer mixture is prepared by mixing about 1 part of the toner material used in Example 1 with about 100 parts of the carrier material used in Example I, except that when the toner particles are measured, about Particle size distribution micro index of 1.70, approx.
a particle size volume distribution coarseness index of 33, and about 13% of the toner particles have an average particle diameter of about 5 microns or less;
A percentage of the toner particles, about 12%, have an average particle diameter of about 5 to about 8 microns; a percentage of the toner particles, about 50%, have an average particle diameter of about 8 to about 12 microns; A few percentages, about 5%, had a particle size distribution with an average particle diameter of 20 microns or greater.

The carrier material was measured and had the following particle size distribution:
This distribution is artificially reconstructed and does not satisfy the semi-log plot for geometric standard deviation calculations.

According to calculations, this coated ferrite carrier material has a specific surface area of approximately 177 cd/7. This developer is used under substantially the same conditions as in Example 1 to develop an electrostatic latent image. When the test was stopped, the developer mixture was at 400
It turned out that I was able to make up to 000 copies satisfactorily.

Film formation on low-level sensitive materials is approximately 135,000 each
It was observed as a printout on the copy at the tachypace of the copy interval. The ratio of toner sticking was found to be approximately 0.0117. The highly classified developer materials of the present invention are thus characterized as providing improved copy quality due to reduced background toner deposition.

Furthermore, the developer materials of the present invention are further characterized in that they yield improved mechanical properties with even longer system lifetimes, i.e. these developer materials provide substantially improved developer mixtures for a substantially longer period of time. It provides improved triboelectric charging properties, thereby increasing the developer life of the developer mixture and reducing the time between developer material changes. Furthermore, the developer materials of the present invention are characterized by providing denser toner images and are particularly useful in magnetic brush development systems. Thus, by providing the developer materials of the present invention, substantial improvements in system life due to inherent developer life occur based on the classification and use of developer materials with specific physical properties. Furthermore, the developer materials of the present invention are further characterized as experiencing substantially reduced sticking rates resulting in more stable triboelectric charging of the developer mixture for a substantially longer period of time, thereby allowing the development of the developer mixture to Increases developer life and reduces the time between developer material changes.

As used herein, the expression "developer material 1" refers to a developer mixture 1 that includes a toner material or a combination of a toner material and a carrier material.

Although specific materials and conditions are described in the foregoing examples of making and using the developer materials of the present invention, these are intended merely as illustrations of the present invention.

These and other high surface area carrier material toner materials, substitutes, and methods as described above may be substituted for those in the examples with similar results. Other variations of the invention will be available to those skilled in the art upon reading this description.

These are included within the scope of the present invention. Note that aspects of the present invention and related matters are listed below.

(1) A classified electrostatographic toner material according to claim 1 having a particle size distribution microindex of about 2.00 or less.

(2) A classified electrostatographic toner material according to claim 1 having a particle size distribution microindex of about 1.45 or less.

(3) A classified electrostatographic toner material according to claim 1 having a particle size volume distribution coarseness index of about 1.45 or less.

(4) A classified electrostatographic toner material according to claim 1 having a particle size volume distribution coarseness index of about 1.35 or less.

(5) The particle size distribution of the toner particles is such that several percentages of the toner particles have an average particle diameter of about 20% or less of about 5 microns or less, and about 45% of the toner particles have an average particle diameter of about 8 to about 12 microns. A classified electrostatographic toner material according to claim 1 having an average particle diameter of microns, and a percentage of the toner particles, no more than about 5%, having an average particle diameter of about 20 microns or greater.

(6) An electrostatographic developer mixture comprising fine toner particles that electrostatically adhere to the surface of carrier particles, wherein said toner particles have a composition as described in (1) above.

(7) An electrostatographic developer mixture comprising fine toner particles that electrostatically adhere to the surface of carrier particles, wherein said toner particles have a composition as described in (2) above.

(8) An electrostatographic developer mixture comprising fine toner particles that electrostatically adhere to the surface of carrier particles, wherein said toner particles have a composition as described in (3) above.

(9) An electrostatographic developer mixture comprising fine toner particles electrostatically adhering to the surface of carrier particles, wherein said toner material has a composition as described in (4) above.

AO) An electrostatographic developer mixture comprising fine toner particles electrostatically adhering to the surface of carrier particles, wherein said toner material has a composition as described in (5) above.

An electrostatographic developer mixture comprising fine toner particles electrostatically adhering to the surface of carrier particles, wherein said toner material has a composition as claimed in claim 2.

(c) An electrostatographic developer mixture comprising fine toner particles electrostatically adhering to the surface of carrier particles, wherein said toner material has a composition as claimed in claim 3.

13) Providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on the recording surface, and contacting the developer of (6) with the electrostatic latent image. , whereby at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. .

(self) providing an electrostatographic imaging member having a recording surface; forming an electrostatic latent image on the recording surface; and contacting the developer of (7) with the electrostatic latent image; electrostatographic imaging, characterized in that at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. Law.

(self) providing an electrostatographic image forming member having a recording surface, forming an electrostatic latent image on the recording surface, and contacting the developer of claim 12 with the electrostatic latent image. an electrostatographic image characterized by the steps of: causing at least a portion of said fine toner particles to be attracted and deposited on said recording surface in conformity with said electrostatic latent image; Formation method.

(auto) providing an electrostatographic imaging member having a recording surface; forming an electrostatic latent image on the recording surface; and bringing the developer of (9) into contact with the electrostatic latent image; electrostatographic imaging, characterized in that at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. Law.

(5) providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on the recording surface, and contacting the electrostatic latent image with the developer of 00). , whereby at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. .

(auto) providing an electrostatographic image forming member having a recording surface; forming an electrostatic latent image on the recording surface; and bringing the developer of 01) into contact with the electrostatic latent image; , whereby at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image.

(19) providing an electrophotographic imaging member having a recording surface, forming an electrostatic latent image on the recording surface, and contacting the electrostatic latent image with the developer, A method of electrophotographic imaging characterized by the steps of: at least a portion of said fine toner particles being attracted and deposited on said recording surface in conformity with said electrostatic latent image.

An electrostatographic developer mixture according to claim 4, wherein the carrier particles are a classified high surface area carrier material having a specific surface area of at least about 150 cd/V.

An electrostatographic developer mixture according to claim 4, wherein the carrier particles are a classified high surface area carrier material having a specific surface area of at least about 165 Cd/r.

An electrostatographic developer mixture according to claim 4, wherein the carrier particles are a classified high surface area carrier material having a specific surface area of at least about 175 cd/F7.

(c) The electrostatographic developer mixture according to (1) above, wherein the classified carrier material has a particle size volume distribution geometric standard deviation of about 1.3 or less and a volume average particle diameter of about 100 microns or less.

An electrostatographic developer mixture according to the above, wherein the carrier material is coated with a thin continuous film of coating material.

(to) An electrostatographic developer mixture according to the above-mentioned Company, wherein said coating material comprises a nickel-zinc-ferrite coated with a thin continuous film of a coating composition comprising styrene, a methacrylate ester, and an organosilicon compound.

(to) providing an electrostatographic forming member having a recording surface, forming an electrostatic latent image on the recording surface, and contacting the electrostatic latent image with the developer mixture according to (1) above; electrostatographic imaging, characterized in that at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. Law.

(5) providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said electrostatic latent image with a developer mixture according to said Corporation; electrostatographic imaging, characterized in that at least a portion of said fine toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. Law.

(to) providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said electrostatic latent image with a developer mixture according to a method of electrostatographic imaging, characterized in that at least a portion of said toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. .

providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said electrostatic latent image with a developer mixture according to said Corporation. An electrostatographic imaging process characterized by steps whereby at least a portion of said toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image.

(to) providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said latent electrostatic image with a developer mixture according to said Foundation; a method of electrostatographic imaging, characterized in that at least a portion of said toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. .

(b) providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said electrostatic latent image with a developer mixture according to (iii) above; a method of electrostatographic imaging, characterized in that at least a portion of said toner particles are attracted and deposited on said recording surface in conformity with said electrostatic latent image. .

Claims (1)

[Scope of Claims] 1. A particle size number distribution having a fine index ratio of about 2.50 or less, a particle size volume distribution having a coarse index ratio of about 1.5 or less, and a percentage of particles of about 30.0% or less. With an average particle diameter of about 5 microns or less, about 25
% have a diameter of about 8 to about 12 microns, and a fraction of the toner particles have a particle size distribution of about 5% or less having an average particle diameter of about 20 microns or greater. Electrostatographic toner material. 2 A particle size number distribution having a fine index ratio of about 2.50 or less, a particle size volume distribution having a coarse index ratio of about 1.5 or less, and a few percentages of the particles having a coarse index ratio of about 1.5 or less.
A few percentages of the toner particles, about 60%, have an average particle diameter of about 8 to about 12 microns, and a few percentages of the toner particles, about 5%, have an average particle diameter of about 20 microns or less.
A classified electrostatographic toner material characterized by toner particles having a particle size distribution having an average particle diameter of microns or greater. 3 Particle size number distribution with a fine index ratio of about 2.50 or less, a particle size volume distribution with a coarse index ratio of about 1.5 or less, and a percentage of particles with an average of about 5 microns or less, about 30.0% or less The particles have a diameter of about 25
% have a diameter of about 8 to about 12 microns, and a fraction of the toner particles have a particle size distribution of about 5% or less having an average particle diameter of about 20 microns or greater. An electrostatographically developed mixture comprising fine toner particles having an electrostatographic toner material electrostatically adhered to the surface of carrier particles.