CA1147192A - Electrostatographic developer including toner of diameter between 3 and 15 microns and carrier of diameter between 15 and 65 microns - Google Patents
Electrostatographic developer including toner of diameter between 3 and 15 microns and carrier of diameter between 15 and 65 micronsInfo
- Publication number
- CA1147192A CA1147192A CA000322602A CA322602A CA1147192A CA 1147192 A CA1147192 A CA 1147192A CA 000322602 A CA000322602 A CA 000322602A CA 322602 A CA322602 A CA 322602A CA 1147192 A CA1147192 A CA 1147192A
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- Canada
- Prior art keywords
- microns
- particles
- weight
- toner
- carrier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Developing Agents For Electrophotography (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Electrostatographic developer compositions providing substantially improved copy quality are disclosed. The developer compositions comprise toner particles having a particle diameter in the range of between about 3 microns and about 15 microns.
The carrier particles have a particle diameter in the range of between about 15 microns and about 65 microns. Imaging processes employing the developer compositions are also disclosed.
Electrostatographic developer compositions providing substantially improved copy quality are disclosed. The developer compositions comprise toner particles having a particle diameter in the range of between about 3 microns and about 15 microns.
The carrier particles have a particle diameter in the range of between about 15 microns and about 65 microns. Imaging processes employing the developer compositions are also disclosed.
Description
7~
BACKGROUND OF THE INVENTION
This invention relates in general to electrostato-graphic imaging systems, and, in particular, to improved developer materials and their use.
The formation and development of images on the surface o~ photoconductive materials by electrostatic means i9 well-known. The basic electrostatographic process, as taught by C. F. Carlson in U.S. Pat. No. 2,297,691, involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light-and-shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting electros-tatic latent image by depositing on the image a finely divided electroscopic material referred to in the art as "toner".
One technique for developing an electrostatic latent image is the "magnetic brush" process as disclosed, for example, in U.S. Pat. No. 2,874,063. In this method a developer material containing toner and magnetic carrier particles is carried by a magnet. The magnetic field of the magnet causes alignment of the maynetic carriers in a brush-like configuration. This magnetic brush is engaged with an electrostatic latent image-bearing surface and the toner particles are drawn from the brush to the electrostatic image by electrostatic attraction.
Many other methods such as "touchdown" development as dis-closed by C. R. May in U.S. Pat. No. 2,895,847 are known for applying electroscopic particles to the electrostatic latent image to be developed. The development processes as mentioned above, together with numerous variations, are well-known to the art through various patents and publications and through the widespread availability and utilization of electrostatographic imaging equipment.
BACKGROUND OF THE INVENTION
This invention relates in general to electrostato-graphic imaging systems, and, in particular, to improved developer materials and their use.
The formation and development of images on the surface o~ photoconductive materials by electrostatic means i9 well-known. The basic electrostatographic process, as taught by C. F. Carlson in U.S. Pat. No. 2,297,691, involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light-and-shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting electros-tatic latent image by depositing on the image a finely divided electroscopic material referred to in the art as "toner".
One technique for developing an electrostatic latent image is the "magnetic brush" process as disclosed, for example, in U.S. Pat. No. 2,874,063. In this method a developer material containing toner and magnetic carrier particles is carried by a magnet. The magnetic field of the magnet causes alignment of the maynetic carriers in a brush-like configuration. This magnetic brush is engaged with an electrostatic latent image-bearing surface and the toner particles are drawn from the brush to the electrostatic image by electrostatic attraction.
Many other methods such as "touchdown" development as dis-closed by C. R. May in U.S. Pat. No. 2,895,847 are known for applying electroscopic particles to the electrostatic latent image to be developed. The development processes as mentioned above, together with numerous variations, are well-known to the art through various patents and publications and through the widespread availability and utilization of electrostatographic imaging equipment.
-2-While ordinarily capable o~ producing good quality images, conventional developing systems suffer serious deficiencies in certain areas. In the reproduction of high contrast copies such as letters, tracings and the like, it S is desirable to select the electroscopic powder and carrier materials so that their mutual electrication is gcverned in most cases by the distance between their relative positions in the triboelectric series~ However, when otherwise com-patible electroscopic powder and carrier materials are removed from each other in the triboelectric series by too great a distance, the resulting images are very faint because the attractive forces between the carrier and toner particles compete with the attractive forces between the electrostatic latent image and the toner particles. ~lthough the image density may be improved by increasing the toner concentration in the developer mixture, undesirably high background toner deposition as well as increased toner impaction and agglomera tion is encountered when the toner concentration in the developer mixture is excessive. The initial electrostato-graphic plate charge may be increased to improve the density of the deposited powder image, but the plate charge would ordinarily have to be excessively high in order to attract the electroscopic powder away from the carrier particle.
Excessively high electrostatographic plate charges are not only undesirable because of the high power consumption neces-sary to maintain the electrostatographic plate at high potentials, but also because the high potential causes the carrier particles to adhere to the electrostatographic plate surface rather than merely roll across and off the electro-statographic plate surface. Print deletion and massive carryover oE carrier particles often occur when carrier particles adhere to reusable electrosta~ographic imaying surfac~s. Massive carrier carry-over problems are particu-larly acute when the developer is employed in solid area S coverage machines where excessive quantities of toner particles are removed from carr ier particles thereby leaving many carrier particles substantially bare of toner particles.
Further, adherence of carrier particles to reusable electro-statographic imaging surfaces promotes the formation of undesirable scratches on the surfaces during image transfer and surface cleaning operations. It is therefore apparent that many materials which otherwise have suitable properties for employment as developer materials are unsuitable because they possess unsatisfactory properties. In addition, uniform triboelectric surface characteristics of many carrier surfaces are difficult to achieve with mass production techniques.
Quality images are in some instances almost impossible to obtain in high speed automatic machines when carriers having non-uniform triboelectric properties are employed. The addition of large quantities of material to the original carrier material to change the triboelectric properties thereof requires a major manufacturing operation and often undesirably alters the original physical characteristics of the carrier material. Further, it is highly desirable to control the triboelectric properties of carrier surfaces to accommodate the use of desirable toner compositlons while retaining the other desirable physical characterist'ics of the carrierO Another factor affecting the stability of the triboelectric properties of developer materials is the sus-ceptibility of developer particles to "toner impaction".
~ 7~When developer particles are employed in automatic machines and recycled through many cycles, the many collisions which occur between the carrier particles and other surfaces in the machine cause the toner particles carried on the surface of the carrier particles to be welded or otherwise forced - onto the carrier surfaces. The gradual accumulation of impacted toner material on the surface of the carrier causes a chan~e in the triboelectric value of the carrier and directly contribu~es to the degradation of copy quality by eventual destruction of the toner carrying capacity of the carrier.
PRIOR ART
In U.S. Patent 3,942,979, there is disclosed a developer mixture comprising classified toner materials having a particle size distribution wherein less than about 30% by number of the toner particles have an average particle size diameter of less than about 5 microns, about 25% oE the parti-cles have a diameter between about 8 microns and about l~
microns, and less than about 5% by number of the toner particles have an average particle diameter greater than about 20 microns.
The high surface area carrier materials have a specific sur-face of at least about 150 cm2/gram. It is also indicated therein that for cascade and magnetic brush development, the carrier particles generally have an average diameter between about 30 microns and 1000 microns, and between about 30 and about 250 microns, respectively.
Present commercial magnetic brush development systems generally employ carrier particles that are approxi-mately 100 microns in diameter. Toner particles employed with these carrier particles typically have a distribution 71~
of particle sizes that vary from l to 30 microns. Experience with the aforementioned developer materials reveals degra-dation of copy quality as reflected by blurred and mottled prints having poor edge acuity and resolution.
Thus, there is a continuing need for better devel-oper materials for developing electrostatic latent images.
UMM~RY OF THE INVENTION
It is, therefore, an object of an aspect of this invention to provide developer materials which overcome the above noted deficiencies.
It is an object of an aspect of this invention to provide developer materials having more stable electrostato-graphic properties.
It is an object of an aspect of this invention to provide developer materials which have a longer useful life.
It is an object of an aspect of this invention to provide developer materials which are less susceptible to toner impaction.
It is an object of an aspect of this invention to provide developer materials which are more resistant to film formation on electrostatographic recording surfaces.
It is an object of an aspect of this invention to provide developer materials which enable the attainment of copied images having greatly improved quality.
It is an object of an aspect of this invention to provide developer materials having improved triboelectric properties.
An object of an aspect of this invention is to provide developer materials which exhibit improved elec-trical and mechanical properties useful in an electro-statographic apparatus employing magnetic brush develop~
ment apparatus.
.
.~ 9Z
An object of an aspect of this invention is to provide improved developer materials having physical and chemical properties superior to those of known developer materials.
Various aspects of this invention are as follows:
An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles con-sisting essentially of particles having a diameter of between about 3 microns and about 15 microns, and said carrier particles consisting essentially of particles having . a diameter of between about 15 microns and about 65 micxons.
An electrostatographic imaging process compris-ing the steps of providing an electrostatographic imaging member having a recording surface, forming an electro-static latent image on said recording surface, and con-tacting said electrostatic latent image with a developer mixture comprising finely-divided toner particles electro-statically clinging to the surface of carrier particles, said toner particles consisting essentially of particles having a diameter of between about 3 microns and about 15 microns, and said carrier particles consisting essential-ly of particles having a diameter of between about 15 microns and about 65 microns, whereby at least a portion of said finely-divided toner particles are attracted to and deposited on said recording surface in conformance with said electrostatic latent image.
Even better results are obtained when, and it is preferred that, the toner materials have a particle diameter in the range of between about 3 microns and about 10 microns and the carrier materials have a particle diameter in the range of between about 10 microns and about 40 microns. Optimum results are obtained when the toner materials have a particle diameter in the range of between about 3 microns and about 8 microns and the carrier materials have a particle diameter in the range of between about 8 microns and about 24 microns.
It has now been found that the removal from toner materials of toner particles which are below about
Excessively high electrostatographic plate charges are not only undesirable because of the high power consumption neces-sary to maintain the electrostatographic plate at high potentials, but also because the high potential causes the carrier particles to adhere to the electrostatographic plate surface rather than merely roll across and off the electro-statographic plate surface. Print deletion and massive carryover oE carrier particles often occur when carrier particles adhere to reusable electrosta~ographic imaying surfac~s. Massive carrier carry-over problems are particu-larly acute when the developer is employed in solid area S coverage machines where excessive quantities of toner particles are removed from carr ier particles thereby leaving many carrier particles substantially bare of toner particles.
Further, adherence of carrier particles to reusable electro-statographic imaging surfaces promotes the formation of undesirable scratches on the surfaces during image transfer and surface cleaning operations. It is therefore apparent that many materials which otherwise have suitable properties for employment as developer materials are unsuitable because they possess unsatisfactory properties. In addition, uniform triboelectric surface characteristics of many carrier surfaces are difficult to achieve with mass production techniques.
Quality images are in some instances almost impossible to obtain in high speed automatic machines when carriers having non-uniform triboelectric properties are employed. The addition of large quantities of material to the original carrier material to change the triboelectric properties thereof requires a major manufacturing operation and often undesirably alters the original physical characteristics of the carrier material. Further, it is highly desirable to control the triboelectric properties of carrier surfaces to accommodate the use of desirable toner compositlons while retaining the other desirable physical characterist'ics of the carrierO Another factor affecting the stability of the triboelectric properties of developer materials is the sus-ceptibility of developer particles to "toner impaction".
~ 7~When developer particles are employed in automatic machines and recycled through many cycles, the many collisions which occur between the carrier particles and other surfaces in the machine cause the toner particles carried on the surface of the carrier particles to be welded or otherwise forced - onto the carrier surfaces. The gradual accumulation of impacted toner material on the surface of the carrier causes a chan~e in the triboelectric value of the carrier and directly contribu~es to the degradation of copy quality by eventual destruction of the toner carrying capacity of the carrier.
PRIOR ART
In U.S. Patent 3,942,979, there is disclosed a developer mixture comprising classified toner materials having a particle size distribution wherein less than about 30% by number of the toner particles have an average particle size diameter of less than about 5 microns, about 25% oE the parti-cles have a diameter between about 8 microns and about l~
microns, and less than about 5% by number of the toner particles have an average particle diameter greater than about 20 microns.
The high surface area carrier materials have a specific sur-face of at least about 150 cm2/gram. It is also indicated therein that for cascade and magnetic brush development, the carrier particles generally have an average diameter between about 30 microns and 1000 microns, and between about 30 and about 250 microns, respectively.
Present commercial magnetic brush development systems generally employ carrier particles that are approxi-mately 100 microns in diameter. Toner particles employed with these carrier particles typically have a distribution 71~
of particle sizes that vary from l to 30 microns. Experience with the aforementioned developer materials reveals degra-dation of copy quality as reflected by blurred and mottled prints having poor edge acuity and resolution.
Thus, there is a continuing need for better devel-oper materials for developing electrostatic latent images.
UMM~RY OF THE INVENTION
It is, therefore, an object of an aspect of this invention to provide developer materials which overcome the above noted deficiencies.
It is an object of an aspect of this invention to provide developer materials having more stable electrostato-graphic properties.
It is an object of an aspect of this invention to provide developer materials which have a longer useful life.
It is an object of an aspect of this invention to provide developer materials which are less susceptible to toner impaction.
It is an object of an aspect of this invention to provide developer materials which are more resistant to film formation on electrostatographic recording surfaces.
It is an object of an aspect of this invention to provide developer materials which enable the attainment of copied images having greatly improved quality.
It is an object of an aspect of this invention to provide developer materials having improved triboelectric properties.
An object of an aspect of this invention is to provide developer materials which exhibit improved elec-trical and mechanical properties useful in an electro-statographic apparatus employing magnetic brush develop~
ment apparatus.
.
.~ 9Z
An object of an aspect of this invention is to provide improved developer materials having physical and chemical properties superior to those of known developer materials.
Various aspects of this invention are as follows:
An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles con-sisting essentially of particles having a diameter of between about 3 microns and about 15 microns, and said carrier particles consisting essentially of particles having . a diameter of between about 15 microns and about 65 micxons.
An electrostatographic imaging process compris-ing the steps of providing an electrostatographic imaging member having a recording surface, forming an electro-static latent image on said recording surface, and con-tacting said electrostatic latent image with a developer mixture comprising finely-divided toner particles electro-statically clinging to the surface of carrier particles, said toner particles consisting essentially of particles having a diameter of between about 3 microns and about 15 microns, and said carrier particles consisting essential-ly of particles having a diameter of between about 15 microns and about 65 microns, whereby at least a portion of said finely-divided toner particles are attracted to and deposited on said recording surface in conformance with said electrostatic latent image.
Even better results are obtained when, and it is preferred that, the toner materials have a particle diameter in the range of between about 3 microns and about 10 microns and the carrier materials have a particle diameter in the range of between about 10 microns and about 40 microns. Optimum results are obtained when the toner materials have a particle diameter in the range of between about 3 microns and about 8 microns and the carrier materials have a particle diameter in the range of between about 8 microns and about 24 microns.
It has now been found that the removal from toner materials of toner particles which are below about
3 microns will provide a developer mixture having improved carrier life, background deposits are minimized, and photoreceptor cleaning is greatly facilitated.
More particularly, toner particles having a diameter below 3 microns usually encompass free colorant such as carbon black, and unpigmented 7a-platelets which are undesirable since they inhibit proper triboelectric charging and reduce the active carrier sur~ace area resulting in high background deposition of such particles.
By considering the particle size of toner particles relative to copy quality, a particle size range of 3 to 15 microns with a mean particle size of about 2 microns has been found to provide maximum copy quality. Apparently, toner particles having a diameter below 3 microns are tribo-electrically charged too highly and they tend to not be developed as easily as the larger particles and also prevent the larger particles from being charged high enough. These lower charged larger particles are difficult to control in a developer mixture and will usually undesirably develop onto the background areas of an electrostatic latent image.
It has also been found that the removal from toner materials of toner particles having a diam~ter larger than 15 microns will provide improved copy quality since such particles have been found to produce observable blur in biased transfer roll systems.
It has also been found that conventional 100 micron siæe carrier particles are very quickly impacted with toner particles thus reducing the useful life of such developer mixtures. Thus, in accordance with this invention, by employing toner particles having a diameter between 3 and 15 microns with carrier particles having a diameter of between 15 and 65 microns, this carrier size range increases the surface area of the carrier material to acccmmodate the toner material as described above and generates lower impaction energies The net result of the developer mixtures of this invention is the provision of prints produced by the electro-statographic process wherein the printed image now has improved edge acuity, high resolution, and sharp, crisp characters. Where an occasional toner particle deposits in background areas, due to the smaller size of the toner particles employed, the background deposit is not perceivable by the naked eye. Likewise, due to the smaller size of the carrier particles employed in the developer mixtures of this invention, it is now possible for the carrier particles to carry sufficient toner particles to enable development of large solid areas without employing excessively high toner concentra-tions which previously led to unacceptably high image background deposits.
Pursuant to this invention, the enhanced surface/
volume ratio of the developer mass provides increased toner carrying capacity and consequently improved toner concentra-tion latitude. In addition, the developer materials of this invention provide improved insulation between adjacent carrier beads when the carrier particles are made of a conductive metal and the carrier particles do not contain a coating of an insulating material. This is due to the increased popwlation of toner particles between contacting carrier particles which improves the resistance to shorting between conductive carrier particles and the photoreceptor thus allowing for higher bias field latitudeO As indicated, the carrier material should preferably be conductive to realize the virtual electrode effect for maximum development and to prevent build-up of net electrical charge. The combination of developer materials of this invention has been found to provide prints of out-standing high quality which is not discernible from offset prints.
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It has further been found that the developer composi-tions of this invention provide developed imayes having a more uni~orm and lower pile height than achieved with conventional electrostatographic developer compositions. For example, when employing conventional developer compositions in a high speed electrostatographic copying/duplicating machine, such as the Xerox 9200, the developed, unfused image toner pile height is between about 45 and SS microns. ~owever, when employing the novel developer compositions of this invention in the same machine, the developed, unfused image toner pile height is only about 18 microns. In both instances, the image density is about 1.3 but the lower toner pile height obtained with the compositions of this invention is due to their greater covering power; that is, a greater number of toner particles are packed closer together, occluding more ima~e area, absorbing more reflected light, and therefore the perceived image density is the same in both cases yet the toner pile height is much less with these new developer materials.
This finding is significant since there has conventionally been a substantial disparity in toner pile height between developed, unfused solid image areas and developed, unfused line image areas. However, with the developer co~positions of this invention, the toner pile height of developed, unfused solid image areas and that of developed, unfused line image areas is substantially the same. Thus, with uniform toner pile hei~hts in both the solid imaye areas and the line image areas, it is now possible to obtain a transferred and fused image having a more uniform output density and a greatly improved physical appearance. This is due to greatly improved toner image transfer to a permanent substrate such as paper since, in conventional transEer systems, toner particle size and toner pile height affect transEer efficiency. That is, excessively small toner particles were previously left behind on the pnotoreceptor during transfer resulting in wasted toner, a non-uniform transferred image was obtained, and photoreceptor cleaning problems were aggravated. ~owever, with efficient transfer of developed, unfused solid and line image areas having uniform and lower toner pile heights, fusing of the toner material is more efficient, more uniform, and requires substantially less energy. Also, since less fusing energy is required, copy paper degradation problems such as curling, reduced moisture content, resistivity, and paper transport problems are minimizèd.
Any suitable particle classification method may be em-ployed to obtain the toner materials of this invention. Typical particle classification methods include air classification, screening, cyclone separation, elutriation, centrification, and combinations thereof. The preferred method of obtaining the toner materials of this invention is by centrifugal air classification. In this method, air or some other gas flows inwards in a spiral path through a flat, cylindrical chamber.
Particles contained in the air flow are exposed to two anta-gonistic forces, viz., to the inwardly directed tractive force of the air, and to the outwardly directed centrifugal force of the particle. For a definite size of particlesJ that is, the "cut size," both forces are in equilibrium. Larger (heavier~
particles are dominated by the mass-dependent centrifugal force and the smaller (lighter) particles by the frictional force proportional to the particle diameter. Consequently, the larger or heavier particles fly outwards as coarse frac-7~
tion, while the smaller or lighter ones are carried inwards by the air as fine frac-tion. The "cut size" usually depends upon the gradient o~ the spiral, the peripheral component, and the absolute dimension of the classifying chamber.
Adjustment of the cut size may be effected through variation of the two factors first mentioned, while the range of the cut size may be determined by the respective dimension of the classifying chamber. Satisfactory centrifugal air classifi-cation results may be obtained when employing an apparatus 1 ~ such as the Mikroplex Spiral Air Classifier Type 132MP model available from the Alpine American Corporation, Natick, Massachusetts, or an Acucut Model B18 unit available from ~k the Donaldson Company, I~c., Tulsa, Oklahoma.
Any suitable particle classification method may be employed to obtain the carrier materials of this invention.
Typi~al particle classification methods include air classi-fication, screening, cyclone separation, elutriation, centrification, and combinations thereof. The preferred method of obtaining the carrier materials of this invention is by screening or seiving.
Any suitable vinyl resin having a melting point of at least about 110F may be employed in the toner compositions.
The vinyl resin may be a homopolymer or a copolymer of two or more vinyl monomers. Typical monomeric units which may be employed to form vinyl polymers include: styrene, p-chloro-styrene, vinyl naphthalene; ethylenically unsaturated mono-olefins such as ethylene, propylene, butylene, isobutylene and the like; vinyl esters such as vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the like; esters of 7~rdJQ ,~
alphamethylene aliphatic monocarboxylic acids such as methyl acrylate, e~hyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-alpha-chloroacrylate, methyl meth-acrylate, ethyl methacrylate, butyl methacrylate and the like; acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone 10. and the like; vinylidene halides such as vinylidene chloride, vinylidene chlorofluoride and the like; and N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidine and the like, and mixtures thereof.
Generally, suitable vinyl resins employed in the toner have a weight average molecular weight between about 3,000 to about 500,000.
Toner resins containing relatively high percentages of a styrene resin are preferred. The presence of a styrene resin is preferred because a greater degree of image defini-tion is generally achieved upon latent image development.
Further, denser images are obtained when at least about 25 percent by weight, based on the total weight of resin in the tonerl of a styrene resin is present in the toner. The styrene resin may be a homopolymer of styrene or styrene homologues or copolymers of styrene with other monomeric groups containing a single methylene group attached to a carbon atom by a double bond. Thus,`typical monomeric materials which may be copolymeriæed with styrene by addition polymerization include: P-chlorostyrene, vinyl naphthalene, ethylenically unsaturated monoolefins such as ethylene, ~13-19~
propylene, butylene, isobutylene and the like; vinyl esters such as vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the like; esters of alpha-methylene aliphatic mono-carboxylic acids such as methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-alpha-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like; acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone and the like; vinyli-dene halides such as vinylidene chloride, vinylidene chloro-fluoride and the like; and N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidine and the like; and mixtures thereof. The styrene resins may also be formed by the polmerization of mixtures of two or more of these unsaturated monomeric materials with a styrene monomer. The expression "addition polymerization" is intended to include known polymerization techniques such as free radical, anionic and cationic polymerization processes.
The vinyl resins, including styrene type resins, may also be blended with one or more other resins if desired.
When the vinyl resin is blended with another resin, the added resin is preferably another vinyl resin because the resulting blend is characterized by especially good triboelectric stability and uniform resistance against physical degradation.
The vinyl resins employed for blending with the styrene type or other vinyl resin may be prepared by the addition poly-,.
3 ~
merization of any suitable vinyl monomer such as the vinyl monomers described above. Other thermoplastic re~ins may also be blended with the vinyl resins of this invention.
Typical non-vinyl type 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 styrene copolymerized with another unsaturated monomer or a blend of polystyrene and another 10- resin, a styrene component of at least about 25 percent by weight based on the total weight of the resin present in the toner is preferred because denser images are obtained and a greater degree of image definition i5 achieved with a given quantity of toner material.
lS It is to be understood that the specific formulas given for the units contained in the resins of the toner materials represent the vast majority of the units present, but do not exclude the presence of monomeric units or reactants other than those which have been shown. E'or example, some commercial materials contain trace amounts of homologues or unreacted or partially reacted monomers. Any minor amount of sucb substituents may be present in the materials of this invention.
Any suitabLe pigment or dye may be employed as the colorant for the toner particles. Toner colorants are well-known and include, for example, carbon black, nigrosine dye, aniline blue, Calco Oil Blue, chrome yellow, ultramarine blue, duPont Oil Red, Quinoline Yellow, methylene blue chloride, phthalocyanine blue, Malachite Green Oxalate, lamp b~ack, Rose Bengal and mixtures thereof. The pigment or dye 7~
should be present in the toner in a quantity sufficient to render it highly colored so that it will form a clearly visible image on a recording member. Thus, for example, where conven-tlonal electrostatographic copies of typed documents are desired, the toner may comprise a black pigment such as carbon black, for example, furnace black or channel black, or a black dye such as Amaplast Black dye, available from the National Aniline Products, Inc.. Generally, the pigment is employed in an amount from about 1 percent to about 20 percent by weight based on the total weight of the colored toner. If the toner colorant employed is a dye, substantially smaller quantities of colorant may be used~ However, since a number of the above pigments used in electrostatographic toner compositions may affect both the glass transition and fusion temperatures of the toner compositions of this invention, their concentration preferably should be less than about 10 percent by weight of the colored toner. Representative patents in which toner and developer materials are disclosed include U.S. Patent 2,788,288, U.S. Patent 3,079,342, U.S.
Reissue Patent 25,136, U.S. Patent 3,577,3~5, U.S. Patent 3,653,893, U.S. Patent 3,590,000, U.S. Patent 3,655,374, U.S.
Patent 3,720,617, and U.S. Patent 3,819,367. Especially pre-ferred for use in the present invention are those compositions disclosed in U.S. Reissue Patent 25,136 and U.S. Patent 3,079,342 containing a copolymer of styrene and alkyl meth-acrylate; the compositions disclosed in U.S. Patent 3,590,000 comprising a solid, stable hydropholic metal salt of a fatty acid such as zinc stearate, and a polymeric esterification product of a dicarboxylic acid and a diol comprising a diphenol;
and the compositions disclosed in U.S. Patent 3,819,367 con-., 7:~3~
taining a minor proportion of submicroscopic silican dioxide additive particles.
The toner compositions may be prepared by an well-known toner mixing and comminution technique. For example, the ingredients may be thoroughly mixed by blending, mixing and milling the components and thereafter micro-pulverizing the resulting mixture. Another well-known technique for forming toner particles is to spray-dry a ball-milled toner composition comprising a colorant, a resin, and a solvent.
Any suitable coated or uncoated electrostatographic carrier bead material may be employed as the carrier material of this invention. Typical carriers include sodium chloride, ammonium chloride, aluminum potassium chloride, Rochelle salt, sodium nitrate, aluminum nitrate, potassium chlorate, granular zircon, granular silicon, methyl methacrylate, glass and silicon dioxide. Typical magnetic brush development process carriers include nickel, steel, iron, ferrites, and the like, and are preferred in the compositions of this invention. The carriers may be employed with or without a coating. Many of the foregoing and other typical carriers are described by L. E. Walkup, et al in U.S. Pat.
No. 2,638,416 and E. N. Wise in U.S. Pat. No. 2,618,552.
Additionally, it is preferred that the carrier materials have semi-conductive to conductive properties. Where desired, the carrier materials o~ this invention may be coated with àny suitable insulating material. Typical electrostatographic carrier particle coating materials include vinyl chloride-vinyl acetate copolymers, styrene-acrylate-organosilicon terpolymers, natural resins such as ~L7~9;~:
caoutchouc, colophony, copal, dammar~ jalap, storax; thermo plastic resins including the polyolefins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyls and polyvinylidenes such as poly-styrene, polymethylstyrene, polymethyl methacrylate, poly-acrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ethers, and polyvinyl ketones; fluorocarbons such as poly-tetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride; and polychlorotrifluoroethylene; polyamides such as polycaprolactam and polyhexamethylene adipamide; poly-esters such as polyethylene terephthalate; polyurethanes;
polysulfides, polycarbonates, 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; and the like. Many of the foregoing and other typical carrier coating materials are described by L. E. Walkup in U.S. Pat. No. 2,618,551; B. B. Jacknow, et al.
in U.S. Pat. No. 3,526,433; and R. J. Hagenbach, et al. in U.S. Pat. Nos. 3,533,835 and 3,658,500.
When the carrier materials of this invention are coated, any suitable electrostatographic carrier coating thickness may be employed~ However, a carrier coating having a thickness of at least sufficient to form a thin film on the carrier particle is preferred because the carrier coating will then possess sufficient thickness to resist abrasion and prevent pinholes which adversely affec~ the triboelectric properties of the coated carrier particles. Generally, for cascade and magnetic brush development, the carrier coating L9~
may comprise from about 0.1 percent to about 10.0 percent by weight based on the weight of the coated carrier particles.
Preferably, the carrier coating should comprise from about 0.3 percent to about 1.5 percent by weight based on the weight of the coated carrier particles because maximum durability, toner impaction resistance, and cop~ quality are achieved. To achieve further variation in the proper-ties of the coated composite carrier particles, well-known additives such as plasticizers, reactive and non-reactive polymers, dyes, pigments, wetting agents and mixtures thereof may be mixed with the coating materials and the coating may be continuous or discontinuous.
When the carrier materials of this invention are coated, the carrier coating composition may be applied to the carrier cores by any conventional method such as spraying, dipping, fluidized bed coating, tumbling, brushing, and the like. The coating compositions may be applied as a powder, a dispersion, solution, emulsion or hot melt~ When applied as a solution, any suitable solvent may be employed.
Solvents having relatively low boiling points are preferred because less energy and time is required to remove the solvent subsequent to application of the coating to the carrier cores.
I~ desired, the coating may comprise resin monomers which are polymerized in situ on the surface of the cores or plastisols gelled in situ to a non-flowable state on the surface of the cores. Surprisingly, increased carrier active area increases the net toner material triboelectric charge lev~l for a given toner concentration by weight in a developer mixture. There-fore, where it is preferred to operate an electrostatographic development system at a minimum toner concentration as to .
.
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provide solid area coverage and at a toner concentration high enough to minimize toner deposits in background areas of a developed electrostatic latent image resulting from toner particles having a low or weak triboelectric charge, these objectives may be attained by employing the developer materials of this invention. In accordance with this invention, the aforementioned objectives are attained by operating at an increased toner concentration yet providing lower background deposits and enabling longer developer life.
Any suitable organic or inorganic photoconductive material may be employed as the recording surface with the developer materials of this invention. Typical inorganic photoconductor materials include: sulfur, selenium, zinc sulfide, zinc oxide, zinc cadmium sulfide, zinc magnesium oxide, cadmium selenide, zinc silicate, calcium strontium sulfide, cadmium sulfide, mercuric iodide, mercuric oxide, mercuric sul~ide, indium trisulfide, gallium selenide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, antimony trisulfide, cadmium sulfo-selenide and mixtures thereof. Typical organic photoconductors include: quin-acridone pigments, phthalocyanine pigments, triphenylamine, 2,4-bis(4,4'-diethylamino-phenol)-1, 3,4-oxadiazol, N-iso-propylcarbazole, triphenylpyrrole, 4,5-diphenylimidazolidinone,
More particularly, toner particles having a diameter below 3 microns usually encompass free colorant such as carbon black, and unpigmented 7a-platelets which are undesirable since they inhibit proper triboelectric charging and reduce the active carrier sur~ace area resulting in high background deposition of such particles.
By considering the particle size of toner particles relative to copy quality, a particle size range of 3 to 15 microns with a mean particle size of about 2 microns has been found to provide maximum copy quality. Apparently, toner particles having a diameter below 3 microns are tribo-electrically charged too highly and they tend to not be developed as easily as the larger particles and also prevent the larger particles from being charged high enough. These lower charged larger particles are difficult to control in a developer mixture and will usually undesirably develop onto the background areas of an electrostatic latent image.
It has also been found that the removal from toner materials of toner particles having a diam~ter larger than 15 microns will provide improved copy quality since such particles have been found to produce observable blur in biased transfer roll systems.
It has also been found that conventional 100 micron siæe carrier particles are very quickly impacted with toner particles thus reducing the useful life of such developer mixtures. Thus, in accordance with this invention, by employing toner particles having a diameter between 3 and 15 microns with carrier particles having a diameter of between 15 and 65 microns, this carrier size range increases the surface area of the carrier material to acccmmodate the toner material as described above and generates lower impaction energies The net result of the developer mixtures of this invention is the provision of prints produced by the electro-statographic process wherein the printed image now has improved edge acuity, high resolution, and sharp, crisp characters. Where an occasional toner particle deposits in background areas, due to the smaller size of the toner particles employed, the background deposit is not perceivable by the naked eye. Likewise, due to the smaller size of the carrier particles employed in the developer mixtures of this invention, it is now possible for the carrier particles to carry sufficient toner particles to enable development of large solid areas without employing excessively high toner concentra-tions which previously led to unacceptably high image background deposits.
Pursuant to this invention, the enhanced surface/
volume ratio of the developer mass provides increased toner carrying capacity and consequently improved toner concentra-tion latitude. In addition, the developer materials of this invention provide improved insulation between adjacent carrier beads when the carrier particles are made of a conductive metal and the carrier particles do not contain a coating of an insulating material. This is due to the increased popwlation of toner particles between contacting carrier particles which improves the resistance to shorting between conductive carrier particles and the photoreceptor thus allowing for higher bias field latitudeO As indicated, the carrier material should preferably be conductive to realize the virtual electrode effect for maximum development and to prevent build-up of net electrical charge. The combination of developer materials of this invention has been found to provide prints of out-standing high quality which is not discernible from offset prints.
g~
It has further been found that the developer composi-tions of this invention provide developed imayes having a more uni~orm and lower pile height than achieved with conventional electrostatographic developer compositions. For example, when employing conventional developer compositions in a high speed electrostatographic copying/duplicating machine, such as the Xerox 9200, the developed, unfused image toner pile height is between about 45 and SS microns. ~owever, when employing the novel developer compositions of this invention in the same machine, the developed, unfused image toner pile height is only about 18 microns. In both instances, the image density is about 1.3 but the lower toner pile height obtained with the compositions of this invention is due to their greater covering power; that is, a greater number of toner particles are packed closer together, occluding more ima~e area, absorbing more reflected light, and therefore the perceived image density is the same in both cases yet the toner pile height is much less with these new developer materials.
This finding is significant since there has conventionally been a substantial disparity in toner pile height between developed, unfused solid image areas and developed, unfused line image areas. However, with the developer co~positions of this invention, the toner pile height of developed, unfused solid image areas and that of developed, unfused line image areas is substantially the same. Thus, with uniform toner pile hei~hts in both the solid imaye areas and the line image areas, it is now possible to obtain a transferred and fused image having a more uniform output density and a greatly improved physical appearance. This is due to greatly improved toner image transfer to a permanent substrate such as paper since, in conventional transEer systems, toner particle size and toner pile height affect transEer efficiency. That is, excessively small toner particles were previously left behind on the pnotoreceptor during transfer resulting in wasted toner, a non-uniform transferred image was obtained, and photoreceptor cleaning problems were aggravated. ~owever, with efficient transfer of developed, unfused solid and line image areas having uniform and lower toner pile heights, fusing of the toner material is more efficient, more uniform, and requires substantially less energy. Also, since less fusing energy is required, copy paper degradation problems such as curling, reduced moisture content, resistivity, and paper transport problems are minimizèd.
Any suitable particle classification method may be em-ployed to obtain the toner materials of this invention. Typical particle classification methods include air classification, screening, cyclone separation, elutriation, centrification, and combinations thereof. The preferred method of obtaining the toner materials of this invention is by centrifugal air classification. In this method, air or some other gas flows inwards in a spiral path through a flat, cylindrical chamber.
Particles contained in the air flow are exposed to two anta-gonistic forces, viz., to the inwardly directed tractive force of the air, and to the outwardly directed centrifugal force of the particle. For a definite size of particlesJ that is, the "cut size," both forces are in equilibrium. Larger (heavier~
particles are dominated by the mass-dependent centrifugal force and the smaller (lighter) particles by the frictional force proportional to the particle diameter. Consequently, the larger or heavier particles fly outwards as coarse frac-7~
tion, while the smaller or lighter ones are carried inwards by the air as fine frac-tion. The "cut size" usually depends upon the gradient o~ the spiral, the peripheral component, and the absolute dimension of the classifying chamber.
Adjustment of the cut size may be effected through variation of the two factors first mentioned, while the range of the cut size may be determined by the respective dimension of the classifying chamber. Satisfactory centrifugal air classifi-cation results may be obtained when employing an apparatus 1 ~ such as the Mikroplex Spiral Air Classifier Type 132MP model available from the Alpine American Corporation, Natick, Massachusetts, or an Acucut Model B18 unit available from ~k the Donaldson Company, I~c., Tulsa, Oklahoma.
Any suitable particle classification method may be employed to obtain the carrier materials of this invention.
Typi~al particle classification methods include air classi-fication, screening, cyclone separation, elutriation, centrification, and combinations thereof. The preferred method of obtaining the carrier materials of this invention is by screening or seiving.
Any suitable vinyl resin having a melting point of at least about 110F may be employed in the toner compositions.
The vinyl resin may be a homopolymer or a copolymer of two or more vinyl monomers. Typical monomeric units which may be employed to form vinyl polymers include: styrene, p-chloro-styrene, vinyl naphthalene; ethylenically unsaturated mono-olefins such as ethylene, propylene, butylene, isobutylene and the like; vinyl esters such as vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the like; esters of 7~rdJQ ,~
alphamethylene aliphatic monocarboxylic acids such as methyl acrylate, e~hyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-alpha-chloroacrylate, methyl meth-acrylate, ethyl methacrylate, butyl methacrylate and the like; acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone 10. and the like; vinylidene halides such as vinylidene chloride, vinylidene chlorofluoride and the like; and N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidine and the like, and mixtures thereof.
Generally, suitable vinyl resins employed in the toner have a weight average molecular weight between about 3,000 to about 500,000.
Toner resins containing relatively high percentages of a styrene resin are preferred. The presence of a styrene resin is preferred because a greater degree of image defini-tion is generally achieved upon latent image development.
Further, denser images are obtained when at least about 25 percent by weight, based on the total weight of resin in the tonerl of a styrene resin is present in the toner. The styrene resin may be a homopolymer of styrene or styrene homologues or copolymers of styrene with other monomeric groups containing a single methylene group attached to a carbon atom by a double bond. Thus,`typical monomeric materials which may be copolymeriæed with styrene by addition polymerization include: P-chlorostyrene, vinyl naphthalene, ethylenically unsaturated monoolefins such as ethylene, ~13-19~
propylene, butylene, isobutylene and the like; vinyl esters such as vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the like; esters of alpha-methylene aliphatic mono-carboxylic acids such as methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-alpha-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like; acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone and the like; vinyli-dene halides such as vinylidene chloride, vinylidene chloro-fluoride and the like; and N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidine and the like; and mixtures thereof. The styrene resins may also be formed by the polmerization of mixtures of two or more of these unsaturated monomeric materials with a styrene monomer. The expression "addition polymerization" is intended to include known polymerization techniques such as free radical, anionic and cationic polymerization processes.
The vinyl resins, including styrene type resins, may also be blended with one or more other resins if desired.
When the vinyl resin is blended with another resin, the added resin is preferably another vinyl resin because the resulting blend is characterized by especially good triboelectric stability and uniform resistance against physical degradation.
The vinyl resins employed for blending with the styrene type or other vinyl resin may be prepared by the addition poly-,.
3 ~
merization of any suitable vinyl monomer such as the vinyl monomers described above. Other thermoplastic re~ins may also be blended with the vinyl resins of this invention.
Typical non-vinyl type 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 styrene copolymerized with another unsaturated monomer or a blend of polystyrene and another 10- resin, a styrene component of at least about 25 percent by weight based on the total weight of the resin present in the toner is preferred because denser images are obtained and a greater degree of image definition i5 achieved with a given quantity of toner material.
lS It is to be understood that the specific formulas given for the units contained in the resins of the toner materials represent the vast majority of the units present, but do not exclude the presence of monomeric units or reactants other than those which have been shown. E'or example, some commercial materials contain trace amounts of homologues or unreacted or partially reacted monomers. Any minor amount of sucb substituents may be present in the materials of this invention.
Any suitabLe pigment or dye may be employed as the colorant for the toner particles. Toner colorants are well-known and include, for example, carbon black, nigrosine dye, aniline blue, Calco Oil Blue, chrome yellow, ultramarine blue, duPont Oil Red, Quinoline Yellow, methylene blue chloride, phthalocyanine blue, Malachite Green Oxalate, lamp b~ack, Rose Bengal and mixtures thereof. The pigment or dye 7~
should be present in the toner in a quantity sufficient to render it highly colored so that it will form a clearly visible image on a recording member. Thus, for example, where conven-tlonal electrostatographic copies of typed documents are desired, the toner may comprise a black pigment such as carbon black, for example, furnace black or channel black, or a black dye such as Amaplast Black dye, available from the National Aniline Products, Inc.. Generally, the pigment is employed in an amount from about 1 percent to about 20 percent by weight based on the total weight of the colored toner. If the toner colorant employed is a dye, substantially smaller quantities of colorant may be used~ However, since a number of the above pigments used in electrostatographic toner compositions may affect both the glass transition and fusion temperatures of the toner compositions of this invention, their concentration preferably should be less than about 10 percent by weight of the colored toner. Representative patents in which toner and developer materials are disclosed include U.S. Patent 2,788,288, U.S. Patent 3,079,342, U.S.
Reissue Patent 25,136, U.S. Patent 3,577,3~5, U.S. Patent 3,653,893, U.S. Patent 3,590,000, U.S. Patent 3,655,374, U.S.
Patent 3,720,617, and U.S. Patent 3,819,367. Especially pre-ferred for use in the present invention are those compositions disclosed in U.S. Reissue Patent 25,136 and U.S. Patent 3,079,342 containing a copolymer of styrene and alkyl meth-acrylate; the compositions disclosed in U.S. Patent 3,590,000 comprising a solid, stable hydropholic metal salt of a fatty acid such as zinc stearate, and a polymeric esterification product of a dicarboxylic acid and a diol comprising a diphenol;
and the compositions disclosed in U.S. Patent 3,819,367 con-., 7:~3~
taining a minor proportion of submicroscopic silican dioxide additive particles.
The toner compositions may be prepared by an well-known toner mixing and comminution technique. For example, the ingredients may be thoroughly mixed by blending, mixing and milling the components and thereafter micro-pulverizing the resulting mixture. Another well-known technique for forming toner particles is to spray-dry a ball-milled toner composition comprising a colorant, a resin, and a solvent.
Any suitable coated or uncoated electrostatographic carrier bead material may be employed as the carrier material of this invention. Typical carriers include sodium chloride, ammonium chloride, aluminum potassium chloride, Rochelle salt, sodium nitrate, aluminum nitrate, potassium chlorate, granular zircon, granular silicon, methyl methacrylate, glass and silicon dioxide. Typical magnetic brush development process carriers include nickel, steel, iron, ferrites, and the like, and are preferred in the compositions of this invention. The carriers may be employed with or without a coating. Many of the foregoing and other typical carriers are described by L. E. Walkup, et al in U.S. Pat.
No. 2,638,416 and E. N. Wise in U.S. Pat. No. 2,618,552.
Additionally, it is preferred that the carrier materials have semi-conductive to conductive properties. Where desired, the carrier materials o~ this invention may be coated with àny suitable insulating material. Typical electrostatographic carrier particle coating materials include vinyl chloride-vinyl acetate copolymers, styrene-acrylate-organosilicon terpolymers, natural resins such as ~L7~9;~:
caoutchouc, colophony, copal, dammar~ jalap, storax; thermo plastic resins including the polyolefins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyls and polyvinylidenes such as poly-styrene, polymethylstyrene, polymethyl methacrylate, poly-acrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ethers, and polyvinyl ketones; fluorocarbons such as poly-tetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride; and polychlorotrifluoroethylene; polyamides such as polycaprolactam and polyhexamethylene adipamide; poly-esters such as polyethylene terephthalate; polyurethanes;
polysulfides, polycarbonates, 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; and the like. Many of the foregoing and other typical carrier coating materials are described by L. E. Walkup in U.S. Pat. No. 2,618,551; B. B. Jacknow, et al.
in U.S. Pat. No. 3,526,433; and R. J. Hagenbach, et al. in U.S. Pat. Nos. 3,533,835 and 3,658,500.
When the carrier materials of this invention are coated, any suitable electrostatographic carrier coating thickness may be employed~ However, a carrier coating having a thickness of at least sufficient to form a thin film on the carrier particle is preferred because the carrier coating will then possess sufficient thickness to resist abrasion and prevent pinholes which adversely affec~ the triboelectric properties of the coated carrier particles. Generally, for cascade and magnetic brush development, the carrier coating L9~
may comprise from about 0.1 percent to about 10.0 percent by weight based on the weight of the coated carrier particles.
Preferably, the carrier coating should comprise from about 0.3 percent to about 1.5 percent by weight based on the weight of the coated carrier particles because maximum durability, toner impaction resistance, and cop~ quality are achieved. To achieve further variation in the proper-ties of the coated composite carrier particles, well-known additives such as plasticizers, reactive and non-reactive polymers, dyes, pigments, wetting agents and mixtures thereof may be mixed with the coating materials and the coating may be continuous or discontinuous.
When the carrier materials of this invention are coated, the carrier coating composition may be applied to the carrier cores by any conventional method such as spraying, dipping, fluidized bed coating, tumbling, brushing, and the like. The coating compositions may be applied as a powder, a dispersion, solution, emulsion or hot melt~ When applied as a solution, any suitable solvent may be employed.
Solvents having relatively low boiling points are preferred because less energy and time is required to remove the solvent subsequent to application of the coating to the carrier cores.
I~ desired, the coating may comprise resin monomers which are polymerized in situ on the surface of the cores or plastisols gelled in situ to a non-flowable state on the surface of the cores. Surprisingly, increased carrier active area increases the net toner material triboelectric charge lev~l for a given toner concentration by weight in a developer mixture. There-fore, where it is preferred to operate an electrostatographic development system at a minimum toner concentration as to .
.
71~Z
provide solid area coverage and at a toner concentration high enough to minimize toner deposits in background areas of a developed electrostatic latent image resulting from toner particles having a low or weak triboelectric charge, these objectives may be attained by employing the developer materials of this invention. In accordance with this invention, the aforementioned objectives are attained by operating at an increased toner concentration yet providing lower background deposits and enabling longer developer life.
Any suitable organic or inorganic photoconductive material may be employed as the recording surface with the developer materials of this invention. Typical inorganic photoconductor materials include: sulfur, selenium, zinc sulfide, zinc oxide, zinc cadmium sulfide, zinc magnesium oxide, cadmium selenide, zinc silicate, calcium strontium sulfide, cadmium sulfide, mercuric iodide, mercuric oxide, mercuric sul~ide, indium trisulfide, gallium selenide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, antimony trisulfide, cadmium sulfo-selenide and mixtures thereof. Typical organic photoconductors include: quin-acridone pigments, phthalocyanine pigments, triphenylamine, 2,4-bis(4,4'-diethylamino-phenol)-1, 3,4-oxadiazol, N-iso-propylcarbazole, triphenylpyrrole, 4,5-diphenylimidazolidinone,
4,5-diphenyl-imidazolidinethione, 4,5-bis(4'-amino-phenyl)-imidazolidinone, 1,5-dicyanonaphthaLene, 1,4-dicyanonapthalene~
aminophthalodinitrile, nitrophthalodinitrile, 1,2,5,6-tetra-azacyclooctatetracene-(2,4,6,8), 2-mercaptobenzothlazole-2~
phenyl-4-bisphenylideneoxazolone, 6-hydroxy-2 t 3-di(p-methoxyphenyl)-benzofurane, 4-dimethy~aminobenzylidene-benzhydrazide, 3 benzyli-dene-aminocarbazole, polyvinyl carbazole, (~-nitrobenzylidene)--20~
.
p-bromoanile, 2,4-diphenylquinazoline, 1,2,4-triazine,
aminophthalodinitrile, nitrophthalodinitrile, 1,2,5,6-tetra-azacyclooctatetracene-(2,4,6,8), 2-mercaptobenzothlazole-2~
phenyl-4-bisphenylideneoxazolone, 6-hydroxy-2 t 3-di(p-methoxyphenyl)-benzofurane, 4-dimethy~aminobenzylidene-benzhydrazide, 3 benzyli-dene-aminocarbazole, polyvinyl carbazole, (~-nitrobenzylidene)--20~
.
p-bromoanile, 2,4-diphenylquinazoline, 1,2,4-triazine,
5-diphenyl-3-methyl-pyrazoline, 2-(4'dimethylaminophenyl)-benzoxazole, 3-aminocarbazole, and mixtures thereof.
Representative patents in which photoconductive materials are disclosed include U.S. Pat. No. 2,803,542 to Ullrich, U.S. Pat.
No. 2,970,906 to Bixby, U.S. Pat. No. 3,121,006 to Middleton, and U.S. Pat. No. 3,151,982 to Corrsin.
DESCRIPTION OF PREFERRED EMBODIMENTS
The ~ollowing examples further deEine, describe and compare methods of preparing the developer materials of the present invention and of utilizing ~hem to develop electro-static latent images. Parts and percentages are by weight unless otherwise indicated.
EXAMPLE I
A control developer mixture is prepared by mixing a toner composition comprising a mixture of about 90 parts by weight of a copolymer of about 58.0 percent by weight of styrene and about 42.0 percent by weight of n-butyl methacrylate, and about 10 parts by weight of a furnace carbon black with carrier particles. The toner particles were determined to have a particle size of between 8 and 30 microns. The carrier particles comprised 100 micron nickel-zinc ferrite coated with about 0.6 percent by weight, based on the weight o~ the core material, of a carrier coating composition comprising styrene, a methacrylate ester, and an organosilicon compound as dis-closed in U.S. Pat. No. 3,526,533. The coa~ed ferrite carrier material was determined to have a specific surface area of about 151 cm2/gram.
About 1 part by weight of the toner particles was mixed with about 100 parts by weight of the carrier particles to form the developer mixture~ Copies of a standard test pattern were made with the developer mixture in an electro-statographic copying machine employing a magnetic brush development system. It was found that the developer mixture failed after about 300,000 copies. Developer failure was experienced in the form of high background, i.e, exceeding the specified 0.01 background density level at 1.0 solid area density. A high level of photoreceptor filming was observed as print-out on the copies which occurred at a frequency of about every 60,000 intervals. The rate of toner impaction was found to be about 8 mg/g. The copies produced were found to have blurred images, with poor edge acuity. Grey scale and half-tone reproduction quality was poor. Copy resolution was less than 7 line pairs per millimeter and the presence of hollow characters was substantial.
EXAMPLE II
A developer mixture was prepared by mixing about 3 parts of the toner material employed in Example I with about 100 parts of carrier material except that the toner particles were selected to have a particle size of between about 3 and 10 microns. The carrier particles were selected to comprise 35 micron nickel powder. The nickel powder was determined to have a specific surface area of about 450 cm2/gram.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisf2ctorily up to about 300,000 copies after wh1ch the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insigniEicant and not measurable using existing techniques.
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The copies produced contained images free of blur and edge acuity was excellent7 Grey scale and half-tone reproduction quali~y was excellent. Copy resolution was about 10 11ne pairs per miIlimeter and no hollow characters were evident.
EXAMPLE III
A developer mixture was prepared by mixing about 3 parts by weight of a toner composition comprising a mixture of about 88.5 parts by weight of a polymeric esterification product of a dicarboxylic acid and a diol comprising a diphenol, and about 11.5 parts by weight of a carbon black as disclosed in U~S.
Patent 3,590,00~ with about 100 parts by weight of carrier particles. The toner particles were selected to have a particle size of between 3 and 10 microns. The carrier particles com-prised 35 micron nickel powder. By calculation, the nickel powder was determined to have a specific surface area of about 450 cm /gram.
The developer mixture was used to develop an electro-static la~ent image under substantially the same conditions as 2~ in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insignifi-cant and not measurable using existing techniques, The copies produced contained images free of blur and edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resol~tiQn was about 10 line pairs per millimeter and no hollow characters were evident.
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EXAMPLE IV
A developer mixture was prepared by mi~ing about 3 parts of the toner material employed in Example III with about 100 parts of the carrier material employed in Example III
except that about 0.65 parts by weight of submicroscopic silicon '~
B dioxide particles tAerosil R-972) based on the weight o~ the toner particles as described in U.S. Patent 3,819,367 was added to the developer mixture.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was excellent and not measurable using existing techniques.
The copies produced contained images free of blurand edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resolution was about 10 line pairs per millimeter and no hollow characters were evident.
EXAMPLE V
A developer mixture was prepared as in Example IV
except that about 0.35 parts by weight of zinc stearate based on the weight of the toner particles as described in U.S. Patent 3,590,000 was added to the developer mixture.
The developer mixture was used to develop an electro-static latent image under substantially the same c~nditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test 3~ was suspended. No photoreceptor filming was observed as print-JQ ~n~
out on the copies. The rate of toner impaction was insigni~i-cant and was not measurable using existing techniques.
The copies produced contained images free of bl~r and edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resolution was about 10 line pairs per millimeter and no hollow characters were evident.
EXAMPLE VI
A developer mixture was prepared by mixing about 3 parts by weight of a toner composition comprising a mixture of about 80 parts by weight of styrene, about 20 parts by weight of isobutyl methacrylate, and about lO parts by weight of a carbon black with about 100 parts by weight of carrier particles.
The toner particles were determined to have a particle size of between 3 and 10 microns. The carrier particles comprised 35 micron nickel powder.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insignifi-cant and not measurable using existing techniques~
The copies produced contained images free of blur and edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resolution was about lO line pairs per millimeter and no hollow characters were evident.
EXAMP_ VII
A developer mixture was prepared by mixiny about 3 parts by weight of a toner composition comprising a mixture of about ~0 parts by weight of styrene, about 20 parts by weight of isobutyl methacrylate, about 15 parts by weight of diphenyl iso-phthalate, and about 10 parts by weight of a carbon black with about 100 parts by weight of carrier particles. The toner par-ticles were determined to have a particle size o between 3 and 10 microns. The carrier particles comprised 35 micron nickel powder.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insignificant and not measurable using existing techniques.
The copies produced contained images free of blur and edge acutity was excellent. Grey scale and half-tone reproduc-tion quality was excellent. Copy resolution was about 10 line pairs per millimeter and no hollow characters were evident.
Thus, the developer materials of this invention are characterized as providing substantially improved copy quality in the development of electrostatic latent images.
It is believed that developed image resolution is improved due to the toner particle size range. The improved edge acuity'is believed to result from less edge raking~by the smaller carrier particles in the present developer mixtures~
The reduced mottle appearance and absence of hollow charac-ters of copied images obtained appears to result from more uniform latent image development and image transfer due to - ,3~c mo~e uniform triboelectric charge of the developer materials.
Improved grey scale and half-tone reproduction obtained with the developer materials of this inventlon appears to be due to the high developability of these smaller toner particles and the virtual electrode effect at the photoreceptor surface of the smaller conducti~e carrier particles. In addition, developer materials of this invention are further characterized as resulting in improved machine performance with longer systems life, that is, these developer materials provide substantially improved triboelectric charging properties of the developer mixtures for substantially longer periods of time thereby increasing the developer life of the developer mixtures and decreasing the time intervals between replacement of the developer materials. Further still, the developer materials of this invention may be characterized as providing dense images and are particularly useful in magnetic brush development systems. Thus, by providing the developer materials of this invention, substantial improvements in systems life and copy quality result upon the use of developer materials having the specified physical characteristics.
In addition, the developer materials of this invention may be further characterized as experiencing sub-stantially reduced impaction rates resulting in more stable triboelectric charging properties of the developer mixtures for substantially longer periods of time thereby increasing the developer life of the developer mixtures and decreasing the time intervals between replacement of the deve~oper materials.
The expressions "developing material" and "developer mixture" as employed herein are intended to include toner material or combinations of toner material and carrier material.
~1~7~
Although specific materials and conditions are set forth in the above examples of making and using the developer materials of this invention, these are merely intended as illustrations of the present invention. These and other carrier materials, toner materials, substituents, and processes, such as those listed above, may be substitute~ for those in the examples with similar results.
Other modifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.
Representative patents in which photoconductive materials are disclosed include U.S. Pat. No. 2,803,542 to Ullrich, U.S. Pat.
No. 2,970,906 to Bixby, U.S. Pat. No. 3,121,006 to Middleton, and U.S. Pat. No. 3,151,982 to Corrsin.
DESCRIPTION OF PREFERRED EMBODIMENTS
The ~ollowing examples further deEine, describe and compare methods of preparing the developer materials of the present invention and of utilizing ~hem to develop electro-static latent images. Parts and percentages are by weight unless otherwise indicated.
EXAMPLE I
A control developer mixture is prepared by mixing a toner composition comprising a mixture of about 90 parts by weight of a copolymer of about 58.0 percent by weight of styrene and about 42.0 percent by weight of n-butyl methacrylate, and about 10 parts by weight of a furnace carbon black with carrier particles. The toner particles were determined to have a particle size of between 8 and 30 microns. The carrier particles comprised 100 micron nickel-zinc ferrite coated with about 0.6 percent by weight, based on the weight o~ the core material, of a carrier coating composition comprising styrene, a methacrylate ester, and an organosilicon compound as dis-closed in U.S. Pat. No. 3,526,533. The coa~ed ferrite carrier material was determined to have a specific surface area of about 151 cm2/gram.
About 1 part by weight of the toner particles was mixed with about 100 parts by weight of the carrier particles to form the developer mixture~ Copies of a standard test pattern were made with the developer mixture in an electro-statographic copying machine employing a magnetic brush development system. It was found that the developer mixture failed after about 300,000 copies. Developer failure was experienced in the form of high background, i.e, exceeding the specified 0.01 background density level at 1.0 solid area density. A high level of photoreceptor filming was observed as print-out on the copies which occurred at a frequency of about every 60,000 intervals. The rate of toner impaction was found to be about 8 mg/g. The copies produced were found to have blurred images, with poor edge acuity. Grey scale and half-tone reproduction quality was poor. Copy resolution was less than 7 line pairs per millimeter and the presence of hollow characters was substantial.
EXAMPLE II
A developer mixture was prepared by mixing about 3 parts of the toner material employed in Example I with about 100 parts of carrier material except that the toner particles were selected to have a particle size of between about 3 and 10 microns. The carrier particles were selected to comprise 35 micron nickel powder. The nickel powder was determined to have a specific surface area of about 450 cm2/gram.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisf2ctorily up to about 300,000 copies after wh1ch the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insigniEicant and not measurable using existing techniques.
71~Z
The copies produced contained images free of blur and edge acuity was excellent7 Grey scale and half-tone reproduction quali~y was excellent. Copy resolution was about 10 11ne pairs per miIlimeter and no hollow characters were evident.
EXAMPLE III
A developer mixture was prepared by mixing about 3 parts by weight of a toner composition comprising a mixture of about 88.5 parts by weight of a polymeric esterification product of a dicarboxylic acid and a diol comprising a diphenol, and about 11.5 parts by weight of a carbon black as disclosed in U~S.
Patent 3,590,00~ with about 100 parts by weight of carrier particles. The toner particles were selected to have a particle size of between 3 and 10 microns. The carrier particles com-prised 35 micron nickel powder. By calculation, the nickel powder was determined to have a specific surface area of about 450 cm /gram.
The developer mixture was used to develop an electro-static la~ent image under substantially the same conditions as 2~ in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insignifi-cant and not measurable using existing techniques, The copies produced contained images free of blur and edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resol~tiQn was about 10 line pairs per millimeter and no hollow characters were evident.
71~Z
EXAMPLE IV
A developer mixture was prepared by mi~ing about 3 parts of the toner material employed in Example III with about 100 parts of the carrier material employed in Example III
except that about 0.65 parts by weight of submicroscopic silicon '~
B dioxide particles tAerosil R-972) based on the weight o~ the toner particles as described in U.S. Patent 3,819,367 was added to the developer mixture.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was excellent and not measurable using existing techniques.
The copies produced contained images free of blurand edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resolution was about 10 line pairs per millimeter and no hollow characters were evident.
EXAMPLE V
A developer mixture was prepared as in Example IV
except that about 0.35 parts by weight of zinc stearate based on the weight of the toner particles as described in U.S. Patent 3,590,000 was added to the developer mixture.
The developer mixture was used to develop an electro-static latent image under substantially the same c~nditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test 3~ was suspended. No photoreceptor filming was observed as print-JQ ~n~
out on the copies. The rate of toner impaction was insigni~i-cant and was not measurable using existing techniques.
The copies produced contained images free of bl~r and edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resolution was about 10 line pairs per millimeter and no hollow characters were evident.
EXAMPLE VI
A developer mixture was prepared by mixing about 3 parts by weight of a toner composition comprising a mixture of about 80 parts by weight of styrene, about 20 parts by weight of isobutyl methacrylate, and about lO parts by weight of a carbon black with about 100 parts by weight of carrier particles.
The toner particles were determined to have a particle size of between 3 and 10 microns. The carrier particles comprised 35 micron nickel powder.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insignifi-cant and not measurable using existing techniques~
The copies produced contained images free of blur and edge acuity was excellent. Grey scale and half-tone reproduction quality was excellent. Copy resolution was about lO line pairs per millimeter and no hollow characters were evident.
EXAMP_ VII
A developer mixture was prepared by mixiny about 3 parts by weight of a toner composition comprising a mixture of about ~0 parts by weight of styrene, about 20 parts by weight of isobutyl methacrylate, about 15 parts by weight of diphenyl iso-phthalate, and about 10 parts by weight of a carbon black with about 100 parts by weight of carrier particles. The toner par-ticles were determined to have a particle size o between 3 and 10 microns. The carrier particles comprised 35 micron nickel powder.
The developer mixture was used to develop an electro-static latent image under substantially the same conditions as in Example I. It was found that the developer mixture performed satisfactorily up to about 300,000 copies after which the test was suspended. No photoreceptor filming was observed as print-out on the copies. The rate of toner impaction was insignificant and not measurable using existing techniques.
The copies produced contained images free of blur and edge acutity was excellent. Grey scale and half-tone reproduc-tion quality was excellent. Copy resolution was about 10 line pairs per millimeter and no hollow characters were evident.
Thus, the developer materials of this invention are characterized as providing substantially improved copy quality in the development of electrostatic latent images.
It is believed that developed image resolution is improved due to the toner particle size range. The improved edge acuity'is believed to result from less edge raking~by the smaller carrier particles in the present developer mixtures~
The reduced mottle appearance and absence of hollow charac-ters of copied images obtained appears to result from more uniform latent image development and image transfer due to - ,3~c mo~e uniform triboelectric charge of the developer materials.
Improved grey scale and half-tone reproduction obtained with the developer materials of this inventlon appears to be due to the high developability of these smaller toner particles and the virtual electrode effect at the photoreceptor surface of the smaller conducti~e carrier particles. In addition, developer materials of this invention are further characterized as resulting in improved machine performance with longer systems life, that is, these developer materials provide substantially improved triboelectric charging properties of the developer mixtures for substantially longer periods of time thereby increasing the developer life of the developer mixtures and decreasing the time intervals between replacement of the developer materials. Further still, the developer materials of this invention may be characterized as providing dense images and are particularly useful in magnetic brush development systems. Thus, by providing the developer materials of this invention, substantial improvements in systems life and copy quality result upon the use of developer materials having the specified physical characteristics.
In addition, the developer materials of this invention may be further characterized as experiencing sub-stantially reduced impaction rates resulting in more stable triboelectric charging properties of the developer mixtures for substantially longer periods of time thereby increasing the developer life of the developer mixtures and decreasing the time intervals between replacement of the deve~oper materials.
The expressions "developing material" and "developer mixture" as employed herein are intended to include toner material or combinations of toner material and carrier material.
~1~7~
Although specific materials and conditions are set forth in the above examples of making and using the developer materials of this invention, these are merely intended as illustrations of the present invention. These and other carrier materials, toner materials, substituents, and processes, such as those listed above, may be substitute~ for those in the examples with similar results.
Other modifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.
Claims (13)
1. An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles consisting essentially of particles having a diameter of between about 3 microns and about 15 microns, and said carrier particles consisting essentially of particles having a diameter of between about 15 microns and about 65 microns.
2. An electrostatographic developer mixture in accord-ance with claim l wherein said carrier particles comprise a conductive metal.
3. An electrostatographic developer mixture in accordance with claim 2 wherein said conductive metal is selected from the group consisting of nickel, steel, iron, and ferrites.
4. An electrostatographic developer mixture in accordance with claim 1 wherein said carrier particles comprise a core having a coating of an insulating material.
5. An electrostatographic developer mixture in accordance with claim 4 wherein said insulating material comprises from about 0.1% to about 10.0% by weight based on the weight of said carrier particles.
6. An electrostatographic developer mixture in accordance with claim 1 wherein said toner particles comprise a mixture of about 90 parts by weight of a co-polymer of about 58.0% by weight of styrene, about 42.0%
by weight of n-butyl-methacrylate, and about 10 parts by weight of a furnace carbon black.
by weight of n-butyl-methacrylate, and about 10 parts by weight of a furnace carbon black.
7. An electrostatographic developer mixture in accordance with claim 1 wherein said toner particles comprises a mixture of about 88.5 parts by weight of a polymeric esterification product of a dicarboxylic acid and a diol comprising a diphenol and about 11.5 parts by weight of carbon black.
8. An electrostatographic developer mixture in accordance with claim 7 including about 0.65 parts by weight based on the weight of said toner particles of submicroscopic silicon dioxide particles.
9. An electrostatographic developer mixture in accordance with claim 8 including about 0.35 parts by weight based on the weight of said toner particles of zinc stearate.
10. An electrostatographic developer mixture in accordance with claim 1 wherein said toner particles comprises a mixture of about 80 parts by weight of styrene, about 20 parts by weight of isobutyl methacrylate, about 15 parts by weight of diphenyl isophthalate, and about 10 parts by weight of carbon black.
11. An electrostatographic developer mixture com-prising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles consisting essentially of particles having a diameter of between about 3 microns and about 10 microns, and said carrier particles consisting essentially of particles having a diameter of between about 10 microns and about 40 microns.
12. An electrostatographic developer mixture com-prising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles consisting essentially of particles having a diameter of between about 3 microns and about 8 microns, and said carrier particles consisting essentially of particles having a diameter of between about 8 microns and about 24 microns.
13. An electrostatographic imaging process compris-ing the steps of providing an electrostatographic imaging member having a recording surface, forming an electro-static latent image on said recording surface, and con-tacting said electrostatic latent image with a developer mixture comprising finely-divided toner particles electro-statically clinging to the surface of carrier particles, said toner particles consisting essentially of particles having a diameter of between about 3 microns and about 15 microns, and said carrier particles consisting essential-ly of particles having a diameter of between about 15 microns and about 65 microns, whereby at least a portion of said finely-divided toner particles are attracted to and deposited on said recording surface in conformance with said electrostatic latent image.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US89391578A | 1978-04-06 | 1978-04-06 | |
| US893,915 | 1978-04-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1147192A true CA1147192A (en) | 1983-05-31 |
Family
ID=25402330
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000322602A Expired CA1147192A (en) | 1978-04-06 | 1979-02-28 | Electrostatographic developer including toner of diameter between 3 and 15 microns and carrier of diameter between 15 and 65 microns |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0004748B1 (en) |
| JP (1) | JPS54134636A (en) |
| BR (1) | BR7901932A (en) |
| CA (1) | CA1147192A (en) |
| DE (1) | DE2966772D1 (en) |
| MX (1) | MX153082A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5796353A (en) * | 1980-12-06 | 1982-06-15 | Mita Ind Co Ltd | Two component system developer for magnetic brush development |
| JPS5926943B2 (en) * | 1980-12-30 | 1984-07-02 | コニカ株式会社 | Toner for developing electrostatic images |
| JPH079543B2 (en) * | 1983-05-26 | 1995-02-01 | キヤノン株式会社 | Toner for electrostatic image development |
| JPH079544B2 (en) * | 1983-07-29 | 1995-02-01 | キヤノン株式会社 | Toner |
| JPH083659B2 (en) * | 1986-05-16 | 1996-01-17 | キヤノン株式会社 | Toner for developing electrostatic image and developing method |
| JP2787305B2 (en) * | 1986-09-29 | 1998-08-13 | 株式会社リコー | Electrophotographic development method |
| JP2661091B2 (en) * | 1988-01-20 | 1997-10-08 | ミノルタ株式会社 | Developer |
| JPH0776847B2 (en) * | 1990-11-30 | 1995-08-16 | 富士ゼロックス株式会社 | Color toner for slide making |
| JP2985594B2 (en) * | 1992-12-03 | 1999-12-06 | セイコーエプソン株式会社 | Image forming method |
| EP0656130B1 (en) * | 1993-06-22 | 1996-01-31 | Agfa-Gevaert N.V. | Electrostatographic developer composition |
| JPH10221880A (en) * | 1997-02-07 | 1998-08-21 | Toshiba Corp | Electrophotographic developer and developing device using that |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL286305A (en) * | 1961-12-16 | |||
| US3547822A (en) * | 1968-02-01 | 1970-12-15 | Eastman Kodak Co | Scum-retardant carrier particles and compositions thereof |
| JPS4825663B1 (en) * | 1969-03-08 | 1973-07-31 | ||
| US3781207A (en) * | 1968-12-18 | 1973-12-25 | Continental Can Co | Developer mixture for electrostatic printing |
| CA944106A (en) * | 1970-01-12 | 1974-03-26 | Reprographic Materials | Agglomeration of pigment particles and compositions utilizing same |
| GB1279231A (en) * | 1970-04-09 | 1972-06-28 | Sperry Rand Corp | Electrostatographic developer |
| GB1391661A (en) * | 1972-02-20 | 1975-04-23 | Oce Van Der Grinten Nv | Toner powder and its use in electrophotographic copying processes |
| JPS4890747A (en) * | 1972-03-07 | 1973-11-27 | ||
| JPS495637A (en) * | 1972-05-06 | 1974-01-18 | ||
| JPS495636A (en) * | 1972-05-06 | 1974-01-18 | ||
| JPS5116150B2 (en) * | 1972-05-09 | 1976-05-21 | ||
| CA1043149A (en) * | 1974-05-30 | 1978-11-28 | Lewis O. Jones | Classified toner materials, developer mixture and imaging system |
| CA1041344A (en) * | 1974-05-30 | 1978-10-31 | Lewis O. Jones | High surface area carrier |
| CA1132827A (en) * | 1977-11-03 | 1982-10-05 | Jerry J. Abbott | Electrophotographic toner comprising particles of a specific size distribution |
-
1979
- 1979-02-28 CA CA000322602A patent/CA1147192A/en not_active Expired
- 1979-03-29 DE DE7979300512T patent/DE2966772D1/en not_active Expired
- 1979-03-29 BR BR7901932A patent/BR7901932A/en unknown
- 1979-03-29 EP EP79300512A patent/EP0004748B1/en not_active Expired
- 1979-03-30 JP JP3828079A patent/JPS54134636A/en active Granted
- 1979-04-03 MX MX177185A patent/MX153082A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP0004748A2 (en) | 1979-10-17 |
| EP0004748B1 (en) | 1984-03-14 |
| JPS6360381B2 (en) | 1988-11-24 |
| DE2966772D1 (en) | 1984-04-19 |
| MX153082A (en) | 1986-07-30 |
| BR7901932A (en) | 1979-11-27 |
| JPS54134636A (en) | 1979-10-19 |
| EP0004748A3 (en) | 1979-11-14 |
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