CA1062068A - Dry electrophotographic developer - Google Patents
Dry electrophotographic developerInfo
- Publication number
- CA1062068A CA1062068A CA235,750A CA235750A CA1062068A CA 1062068 A CA1062068 A CA 1062068A CA 235750 A CA235750 A CA 235750A CA 1062068 A CA1062068 A CA 1062068A
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- CA
- Canada
- Prior art keywords
- toner
- weight
- developer
- carrier
- present
- 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.)
- Expired
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Classifications
-
- 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
- G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
- G03G9/1087—Specified elemental magnetic metal or alloy, e.g. alnico comprising iron, nickel, cobalt, and aluminum, or permalloy comprising iron and nickel
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- Engineering & Computer Science (AREA)
- Metallurgy (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Developing Agents For Electrophotography (AREA)
Abstract
DRY ELECTROPHOTOGRAPHIC DEVELOPER
ABSTRACT OF THE DISCLOSURE
A dry electrophotographic developer comprising a mixture of uncoated carrier particles formed of aluminum or alloy of aluminum having an aluminum oxide surface and a toner formulated of tinctorial agents and a binder component in which an essential component thereof consists of styrene -butyl methacrylate copolymer.
ABSTRACT OF THE DISCLOSURE
A dry electrophotographic developer comprising a mixture of uncoated carrier particles formed of aluminum or alloy of aluminum having an aluminum oxide surface and a toner formulated of tinctorial agents and a binder component in which an essential component thereof consists of styrene -butyl methacrylate copolymer.
Description
" 106;~0f~1~
S P E C I F I C A T I O N
_ This invention relates to a dry powdered developer composition for visual development of latent electrostatic im-age~. A well known electrostatic imaging process, generally referred to as th~ Xerox process, is originally described in the Carlson patent No.2,297,691 wherein an element carrying a photoconductive layer is given a blanket electrostatic charge, such as by an ion transfer from a corona discharge. Thereafter, the photoconductive layer is exposed to light modified by an image, such as by projection of a photographic image. The il-luminated areas of the charged photoconductive layer, corre-sponding to the non-imaged areas of the original, are rendered conductive whereby the illuminated areas are discharged to ~ave a latent electrostatic image on the photoconductive layer corresponding to the imaged portion of the original.
The resulting latent electrostatic image can there-after be developed by a liquid developer composition, as de-scribed in U.S. Patent No.2,877,133, U-~S, Patent No.2,891,911, and U.S. Patent No.2,907,674, or by a dry powdered aeveloper of the type described in U.S. Patents Nos.2,618,551; 2,618,552,
S P E C I F I C A T I O N
_ This invention relates to a dry powdered developer composition for visual development of latent electrostatic im-age~. A well known electrostatic imaging process, generally referred to as th~ Xerox process, is originally described in the Carlson patent No.2,297,691 wherein an element carrying a photoconductive layer is given a blanket electrostatic charge, such as by an ion transfer from a corona discharge. Thereafter, the photoconductive layer is exposed to light modified by an image, such as by projection of a photographic image. The il-luminated areas of the charged photoconductive layer, corre-sponding to the non-imaged areas of the original, are rendered conductive whereby the illuminated areas are discharged to ~ave a latent electrostatic image on the photoconductive layer corresponding to the imaged portion of the original.
The resulting latent electrostatic image can there-after be developed by a liquid developer composition, as de-scribed in U.S. Patent No.2,877,133, U-~S, Patent No.2,891,911, and U.S. Patent No.2,907,674, or by a dry powdered aeveloper of the type described in U.S. Patents Nos.2,618,551; 2,618,552,
2,638,416; 2,940,934; 2,965,573; 3,079,342; 3,234,904:
3,533,835; 3,809,082; 3,653,893; 3,672,928; 3,681,107;
3,685,113; 3,720,617; 3,725,283, and 3,740,334.
In use either of a liquid developer or a dry powdered developer, the toner particles are attracted to the electro-statically c~arged latent image. The developed image c~n be fixed, as by means of heat or solvent to secure the developed image d~rectly onto the photoconductive layer, or the toner particles can be transferred from the photoconductive layer to a copy sheet, as in a plain paper copier, where the transferred toner is fixed to set the image on the copy sheet.
.. . ..
106;~068 ~::
~,. .
The dry powdered developer can be applied in a number o ways for development of the latent electrostatic image. The -dry developer can be cascaded over the surface of the imaged photoconductive layer or it can be applied by means of a mag-netic brush for development of the latent electrostatic image.
In practice, the dry powdered developer is formulated of toner particles, in finely divided form, in admixture with carrier particles of larger dimension which operate to impart the desired triboelectric relationship with the toner. Thus the toner can be provided with an electrostatic charge that is opposite the electrostatic charge of the image for attraction of the toner particles to the image for direct development.
Instead, the toner particles can be given a charge which is of the same polarity as the charge of the latent image whereby the toner particles are repelled by the image and deposited on the illuminated areas from which the electrostatic charge has been dissipated, in a process referred to as "reversal toning".
As described in the aforementioned patents on dry p0wdered developers, the carrier particles are used over and over again as a 0 mponent of the dry powdered developer to which toner is added to compensate for that which has been re-moved during image development. In order to obtain the proper triboelectric relationship with the toner, it has been the practice to provide the carrier with a surface coating in the form of a resinous material or the like having the desired charac~erastics.
It has been found that the repeated use of carrier particles for image development subjects the coating on the surface to wear and/or chipping with the result th~t the per-3 formance of the carrier degrades with use thereby to limit the ... . . . . . .
106~06~
useful life of the powdered developer and to cause frequent replacementthereof. Loss of performance of the carrier also results from sticking of the toner particles to the surface coating or by being impacted onto the surface coating during use, such as in cascade or magnetic brush development techniques.
This problem could be avoided and the useful life of the carrier particles extended if a suitable dry powdered developer could be provided in which the toner particles were admixed with the carrier that did not require a coating for proper electrical control and which was characterized by sufficient hardness, surface smoothness and strength to resist wear and impacting of the toner particles into the surface.
Thus it is an object of this invention to produce an electrophotographic dry developer composition which overcomes many of the deficiencies of the prior art powdered developers in that it gives a good fill of solids; which makes use of a carrier that does not chip or degrade in use; which makes use of a carrier which is capable of imparting the desired triboelectric relationship with the toner without the need to make use of a surface coating; in which the toner particles do not stick or are not impacted onto the carrier, and which thereafter is characterized by a long useful life, thereby to avoid the need for frequent replacement of the carrier particles or developer, and in which a unique combination exists between the toner and carrier whereby the performance of the dry powdered developer, for visual development of the image, including solids, is greatly improved.
According to the present invention, there is provided a dry electrophotographic developer comprising the mixture of uncoated carrier particles and fine]y divided toner in which the carrier consists essentially of particles of aluminum or alloys thereof of substantially spherical shape and a size within the range of 300-900 ,u and having an oxidized surface and the toner comprises tinctorial agents and a binder in which an essential component of the binder is a styrene - butyl methacrylate copolymer and in which the tinctorial agent is present in an amount within the range of - 3 _ .... .. . , .. , ~ . . - . , 106i~0~
5-30% by weight of the toner, and which optionally includes a solid .~::
lubricant and anti-caking agent. ~`
The new and improved electrophotographic developer of this invention will hereinafter be described with reference to the following examples:
- 3a -~--3 .~
io~o~
:
ExamPle Carrier -- : .
The carrier particles consist of aluminum or an alloy of aluminum having an oxidized surface formed naturally upon exposure to atmospheric conditions or in which the oxidized surface can be formed in an accelerated manner by anodic oxi-dation. Since only a very thin hard film of oxide is desired, it is preferred to let the oxide form on the surface naturally.
. The carrier particles are of a shape which is spherical or nearly spherical and of a size within the range of 300 tc 900 microns.
ExamPle 2 -Toner ComPOsition .~-72% by weight styrene-butyl methacrylate copolymer (Ionac X-130 - Ionac Chemical Company) ~:
8% by weight polyvinyl butyral (XYSG-~Union Carbide) 12% by weight carbon black 8% by weight Oresol Brilliant Blue GN ~Ciba) ExamPle 3 Toner ComPosition 72% by weight styrene-butyl methacrylate copolymer :
(Ionac X-130 ~ Ionac Chemical Company) 8% by weight polyvinyl butyral (XYSG-Union Carbide) . 12% by weight carbon black 8% by weight Oresol Brilliant Blue GN (Ciba) 1.75% by weight zinc stearate ~ Trade Mark 3o , ?
_ 106~0~
Exam~le_4 Toner ComPOsition 72% by weight styrene - butyl methacrylate copolymer (Ionac X-130 - Ionac Chemical Company) ~/O by weight polyvinyl butyral (XYSG-Union Carbidej -12% by weight carbon black 7% by weight Oresol Brilliant Blue GN (Ciba) ' 0.25% by weight fumed silica (Cab-O-Sil M5-Cabot Corp.~ .`."
' 1.75% by weight zinc stearate ExamPle 5 Toner Composition -~
7~/O by weight styrene - butyl methacrylate (Ionac 184) l~/o by weight polyvinyl butyral ' , 12% by weight carbon black, 1.75% by weight zinc stearate ~
0.25% by weight fumed silica ,,~--The materials making up the toner composition are ' '~-first blended for uniform distribution and then extruded as a ', hot melt from an extruder operating at a temperature of 300F.
The extruded ribbon is allow,ed to cool and is then ~roken up into fine particles by rirst pulverizing in a hammer mill which breaks the extrusion into particles of about 1/16, inch and then processing through a jet mill which reduces the toner to fine particles of substantially uniform dimension suit-able for use as a toner, such as from 2 to 20 microns.
In the above formulation, the polyvinyl butyral repre-sents an additional binder which may be empolyed in an amount within the range of 0 to 15% by weight in the com~ination with '' the copolymer of styrene-butyl methacrylate. The polyvinyl 3 butyral can be replaced in whole or in part by corresponding ~'-Trade Mark ' lO~;~V~8 ~
amounts of other thermoplastic resinous binders, such as poly- -vinyl acetal, polyvinyl chloride, polyvinylidene chloride, polyamide, polyacrylate and polyalkyl acrylate, polystyrene or copolymers of styrene and butadiene, and vinyl toluene/buta-diene.
On the other hand, the ability to formulate a dry pwodered developer which enables use of aluminum or an alloy ;~ -.. .
of aluminum having an oxidized surface as a carrier depends greatly upon the formulation of the toner with a styrene-butyl methacrylate as a binder component. It appears that a unique relationship is established between the carrier of aluminum or -;
its alloy and a toner formulated of a binder of styrene-butyl methacrylate whereby the desired tribolelectric effect is de-veloped between the carrier and the toner particles of the de-veloper. While other binders of related composition can be emp~oyed, the development of the image, including full develop-ment of solids, is inferior,,although comparable to many of the commercial toners currently available for development of , . . .
electrostatic images. The amount of styrene-butyl methacrylate in the toner can vary depending somewhat upon the presence of other binders and components, but it is desirable to formulate the toner with the styrene-butyl methacrylate present in an a~Dunt-of at least 50O/o by weight of the toner composition, up to a maximum of about 85% by weight, and preferably in an amount within the range of 65-75% by weight.
The carbon black and the Oresol Brilliant Blue re-present the tinctorial agents of the toner. Such tinctorial agents may be constituted entirely of carbon black or other pigment or entirely of oresol Brilliant Blue or other dyestuffs, 3 such as defined in the aforementioned patents which describe - ,. . ~
106~:068 ,` dry developer compositions. The amount of tinctorial agent, including carbon black or other pigment or dyestuffs, or mix ~
tures thereof, may range from 5-30O/o by weight of the toner and preferably 15-25% by weight of the toner.
The zinc stearate used in Example 3 and/or the fumed `~
silica added in Example 4, operate in the toner to improve the ~`
flow characteristics of the developer and to prevent caking.
Instead of zinc stearate, other dry lubricants or metal soaps can be empolyed, such as calcium stearate, zinc palmitate, or other fatty acid metal salts. Such lubricants or soaps can be ~mp~ in amounts up to 5% by weight of the toner composition and preferably in an amount within the range of 0.2 to 2.0% by weight. Similarly, colloidal silica can be replaced by other anti-caking materials, such as diatomaceous earth, talc, cal-cium carbonate, and the like. Use can be made of such an~
caking materials in amounts up to 1% by weig~t and preferably in an amount of 0.1 to 1~0% by weight of the toner.
The toner and carrier can be admixed in conventional amount$,~suchdas in the ratio of one part by weight toner to 40 to 200 parts by weight carrier, and preferably in the ratio of one part by weight of toner to 75 to 150 parts by weight of carrier. As a matter of fact, lesser amount of toner in the developer composition will suffice to produce a visible image and, as a matter of practice, in formulating the developer com-position, the concentration of toner to carrier is initially less than prescribed above and toner is added with correspond-ing increase in image intensity until the desired intensity is achieved for the particular combination of ~aterials to arrive at the operating toner concentration.
3o 106~0~;8 The dry powder~d toner which is separated from the carrier by attraction to the image can be fixed by conveational means, such as by heat fusion, solvent vapors or the like to set the image on the copy sheet.
Comparison tests were made between toners and car-riers of the invention with other commercially available toners ; ;
and carriers prescribed by dry powdered development of electro-static images. The comparative tests are based on reflective densities taken across a solid imaged area of 3/16 x 3/8 inch, in which measurements were made with a Gamma Scientific scan-ning microdensitometer, with the following results:
Refleçtion Density ~3Carrier Toner Edge Center ~D
EXample 1 Example 2 1.45 1.09 ~ ¦
Example 1 X-4000 1.3S 0.750.60 Example 1 X-3600 1.47 0.700.77 Example 1 H-10 1.40 0.700.70 Example ~1 N-3600 1.45 0.670.77 Example 1 AG-10 1.38 0.620.76 Example 1 ISC-3600 1.28 0.620.66 Example 1 AG-20 1.23 0.500.73 N-3600 Example 2 1.59 0.800.79 ISC-3600 Example 2 1.42 0.650.77 X-3600 Example 2 1.06 0.540.52 H-10 Example 2 1.06 0.520.54 X-3600 X-3600 1.29 0.550.74 AG-10 AG-10 1.26 0.450.81 N-3600 N-3600 1.53 0.640.89 H-10 H-10 1.29 0.530.74 j -8-.:, j , .
;b .
. ' ' .
~of~o~
In the above tabulation, the letters indicate the supplier, such as X for Xerox, H for Hunt Chemicals, N for Nashua Corporation, AG for Agfa-Gevaert, and ISC for Imaging Systems Corporation.
From the above measurements, it will be seen that the -dry developer formulated of the carrier of Example 1 and the .: .
toner of Example 2, in the amount of one part by weight of ton- .
er to lO0 parts by weight of carrier, yields a solid image.
The density at the center is high by comparison with the commercially available developers or any combinations be-tween components thereof with the carrier or toner of Examples 1 or 2. The improvement is significant, as further supported by the measurement ~D.
Thus, in accordance with the practice o this inven-tion, there is produced (1) a developer which makes use of a carrier that does not require a separate surface coating which otherwise subjects the carrier to degradation due to wear, chipping, and the like; (2) a developer which makes use of a carrier which has no tendency for toner particles to become im-pacted onto the surface; (3) a developer which gives improved solids development, possibly by reason of the fact that the carrier provides a highly conductive core in close proximity to the carrier surface, and (4) a developer which embodies a :-unique combination between the carrier and toner which further enhances the development of solid images and intensity of the copy that is produced.
It will be understood that changes may be made in th~
details of formulation, construction and operation without de-parting from the spirit of the invention, especially as defined 3 in the following claims:
3,685,113; 3,720,617; 3,725,283, and 3,740,334.
In use either of a liquid developer or a dry powdered developer, the toner particles are attracted to the electro-statically c~arged latent image. The developed image c~n be fixed, as by means of heat or solvent to secure the developed image d~rectly onto the photoconductive layer, or the toner particles can be transferred from the photoconductive layer to a copy sheet, as in a plain paper copier, where the transferred toner is fixed to set the image on the copy sheet.
.. . ..
106;~068 ~::
~,. .
The dry powdered developer can be applied in a number o ways for development of the latent electrostatic image. The -dry developer can be cascaded over the surface of the imaged photoconductive layer or it can be applied by means of a mag-netic brush for development of the latent electrostatic image.
In practice, the dry powdered developer is formulated of toner particles, in finely divided form, in admixture with carrier particles of larger dimension which operate to impart the desired triboelectric relationship with the toner. Thus the toner can be provided with an electrostatic charge that is opposite the electrostatic charge of the image for attraction of the toner particles to the image for direct development.
Instead, the toner particles can be given a charge which is of the same polarity as the charge of the latent image whereby the toner particles are repelled by the image and deposited on the illuminated areas from which the electrostatic charge has been dissipated, in a process referred to as "reversal toning".
As described in the aforementioned patents on dry p0wdered developers, the carrier particles are used over and over again as a 0 mponent of the dry powdered developer to which toner is added to compensate for that which has been re-moved during image development. In order to obtain the proper triboelectric relationship with the toner, it has been the practice to provide the carrier with a surface coating in the form of a resinous material or the like having the desired charac~erastics.
It has been found that the repeated use of carrier particles for image development subjects the coating on the surface to wear and/or chipping with the result th~t the per-3 formance of the carrier degrades with use thereby to limit the ... . . . . . .
106~06~
useful life of the powdered developer and to cause frequent replacementthereof. Loss of performance of the carrier also results from sticking of the toner particles to the surface coating or by being impacted onto the surface coating during use, such as in cascade or magnetic brush development techniques.
This problem could be avoided and the useful life of the carrier particles extended if a suitable dry powdered developer could be provided in which the toner particles were admixed with the carrier that did not require a coating for proper electrical control and which was characterized by sufficient hardness, surface smoothness and strength to resist wear and impacting of the toner particles into the surface.
Thus it is an object of this invention to produce an electrophotographic dry developer composition which overcomes many of the deficiencies of the prior art powdered developers in that it gives a good fill of solids; which makes use of a carrier that does not chip or degrade in use; which makes use of a carrier which is capable of imparting the desired triboelectric relationship with the toner without the need to make use of a surface coating; in which the toner particles do not stick or are not impacted onto the carrier, and which thereafter is characterized by a long useful life, thereby to avoid the need for frequent replacement of the carrier particles or developer, and in which a unique combination exists between the toner and carrier whereby the performance of the dry powdered developer, for visual development of the image, including solids, is greatly improved.
According to the present invention, there is provided a dry electrophotographic developer comprising the mixture of uncoated carrier particles and fine]y divided toner in which the carrier consists essentially of particles of aluminum or alloys thereof of substantially spherical shape and a size within the range of 300-900 ,u and having an oxidized surface and the toner comprises tinctorial agents and a binder in which an essential component of the binder is a styrene - butyl methacrylate copolymer and in which the tinctorial agent is present in an amount within the range of - 3 _ .... .. . , .. , ~ . . - . , 106i~0~
5-30% by weight of the toner, and which optionally includes a solid .~::
lubricant and anti-caking agent. ~`
The new and improved electrophotographic developer of this invention will hereinafter be described with reference to the following examples:
- 3a -~--3 .~
io~o~
:
ExamPle Carrier -- : .
The carrier particles consist of aluminum or an alloy of aluminum having an oxidized surface formed naturally upon exposure to atmospheric conditions or in which the oxidized surface can be formed in an accelerated manner by anodic oxi-dation. Since only a very thin hard film of oxide is desired, it is preferred to let the oxide form on the surface naturally.
. The carrier particles are of a shape which is spherical or nearly spherical and of a size within the range of 300 tc 900 microns.
ExamPle 2 -Toner ComPOsition .~-72% by weight styrene-butyl methacrylate copolymer (Ionac X-130 - Ionac Chemical Company) ~:
8% by weight polyvinyl butyral (XYSG-~Union Carbide) 12% by weight carbon black 8% by weight Oresol Brilliant Blue GN ~Ciba) ExamPle 3 Toner ComPosition 72% by weight styrene-butyl methacrylate copolymer :
(Ionac X-130 ~ Ionac Chemical Company) 8% by weight polyvinyl butyral (XYSG-Union Carbide) . 12% by weight carbon black 8% by weight Oresol Brilliant Blue GN (Ciba) 1.75% by weight zinc stearate ~ Trade Mark 3o , ?
_ 106~0~
Exam~le_4 Toner ComPOsition 72% by weight styrene - butyl methacrylate copolymer (Ionac X-130 - Ionac Chemical Company) ~/O by weight polyvinyl butyral (XYSG-Union Carbidej -12% by weight carbon black 7% by weight Oresol Brilliant Blue GN (Ciba) ' 0.25% by weight fumed silica (Cab-O-Sil M5-Cabot Corp.~ .`."
' 1.75% by weight zinc stearate ExamPle 5 Toner Composition -~
7~/O by weight styrene - butyl methacrylate (Ionac 184) l~/o by weight polyvinyl butyral ' , 12% by weight carbon black, 1.75% by weight zinc stearate ~
0.25% by weight fumed silica ,,~--The materials making up the toner composition are ' '~-first blended for uniform distribution and then extruded as a ', hot melt from an extruder operating at a temperature of 300F.
The extruded ribbon is allow,ed to cool and is then ~roken up into fine particles by rirst pulverizing in a hammer mill which breaks the extrusion into particles of about 1/16, inch and then processing through a jet mill which reduces the toner to fine particles of substantially uniform dimension suit-able for use as a toner, such as from 2 to 20 microns.
In the above formulation, the polyvinyl butyral repre-sents an additional binder which may be empolyed in an amount within the range of 0 to 15% by weight in the com~ination with '' the copolymer of styrene-butyl methacrylate. The polyvinyl 3 butyral can be replaced in whole or in part by corresponding ~'-Trade Mark ' lO~;~V~8 ~
amounts of other thermoplastic resinous binders, such as poly- -vinyl acetal, polyvinyl chloride, polyvinylidene chloride, polyamide, polyacrylate and polyalkyl acrylate, polystyrene or copolymers of styrene and butadiene, and vinyl toluene/buta-diene.
On the other hand, the ability to formulate a dry pwodered developer which enables use of aluminum or an alloy ;~ -.. .
of aluminum having an oxidized surface as a carrier depends greatly upon the formulation of the toner with a styrene-butyl methacrylate as a binder component. It appears that a unique relationship is established between the carrier of aluminum or -;
its alloy and a toner formulated of a binder of styrene-butyl methacrylate whereby the desired tribolelectric effect is de-veloped between the carrier and the toner particles of the de-veloper. While other binders of related composition can be emp~oyed, the development of the image, including full develop-ment of solids, is inferior,,although comparable to many of the commercial toners currently available for development of , . . .
electrostatic images. The amount of styrene-butyl methacrylate in the toner can vary depending somewhat upon the presence of other binders and components, but it is desirable to formulate the toner with the styrene-butyl methacrylate present in an a~Dunt-of at least 50O/o by weight of the toner composition, up to a maximum of about 85% by weight, and preferably in an amount within the range of 65-75% by weight.
The carbon black and the Oresol Brilliant Blue re-present the tinctorial agents of the toner. Such tinctorial agents may be constituted entirely of carbon black or other pigment or entirely of oresol Brilliant Blue or other dyestuffs, 3 such as defined in the aforementioned patents which describe - ,. . ~
106~:068 ,` dry developer compositions. The amount of tinctorial agent, including carbon black or other pigment or dyestuffs, or mix ~
tures thereof, may range from 5-30O/o by weight of the toner and preferably 15-25% by weight of the toner.
The zinc stearate used in Example 3 and/or the fumed `~
silica added in Example 4, operate in the toner to improve the ~`
flow characteristics of the developer and to prevent caking.
Instead of zinc stearate, other dry lubricants or metal soaps can be empolyed, such as calcium stearate, zinc palmitate, or other fatty acid metal salts. Such lubricants or soaps can be ~mp~ in amounts up to 5% by weight of the toner composition and preferably in an amount within the range of 0.2 to 2.0% by weight. Similarly, colloidal silica can be replaced by other anti-caking materials, such as diatomaceous earth, talc, cal-cium carbonate, and the like. Use can be made of such an~
caking materials in amounts up to 1% by weig~t and preferably in an amount of 0.1 to 1~0% by weight of the toner.
The toner and carrier can be admixed in conventional amount$,~suchdas in the ratio of one part by weight toner to 40 to 200 parts by weight carrier, and preferably in the ratio of one part by weight of toner to 75 to 150 parts by weight of carrier. As a matter of fact, lesser amount of toner in the developer composition will suffice to produce a visible image and, as a matter of practice, in formulating the developer com-position, the concentration of toner to carrier is initially less than prescribed above and toner is added with correspond-ing increase in image intensity until the desired intensity is achieved for the particular combination of ~aterials to arrive at the operating toner concentration.
3o 106~0~;8 The dry powder~d toner which is separated from the carrier by attraction to the image can be fixed by conveational means, such as by heat fusion, solvent vapors or the like to set the image on the copy sheet.
Comparison tests were made between toners and car-riers of the invention with other commercially available toners ; ;
and carriers prescribed by dry powdered development of electro-static images. The comparative tests are based on reflective densities taken across a solid imaged area of 3/16 x 3/8 inch, in which measurements were made with a Gamma Scientific scan-ning microdensitometer, with the following results:
Refleçtion Density ~3Carrier Toner Edge Center ~D
EXample 1 Example 2 1.45 1.09 ~ ¦
Example 1 X-4000 1.3S 0.750.60 Example 1 X-3600 1.47 0.700.77 Example 1 H-10 1.40 0.700.70 Example ~1 N-3600 1.45 0.670.77 Example 1 AG-10 1.38 0.620.76 Example 1 ISC-3600 1.28 0.620.66 Example 1 AG-20 1.23 0.500.73 N-3600 Example 2 1.59 0.800.79 ISC-3600 Example 2 1.42 0.650.77 X-3600 Example 2 1.06 0.540.52 H-10 Example 2 1.06 0.520.54 X-3600 X-3600 1.29 0.550.74 AG-10 AG-10 1.26 0.450.81 N-3600 N-3600 1.53 0.640.89 H-10 H-10 1.29 0.530.74 j -8-.:, j , .
;b .
. ' ' .
~of~o~
In the above tabulation, the letters indicate the supplier, such as X for Xerox, H for Hunt Chemicals, N for Nashua Corporation, AG for Agfa-Gevaert, and ISC for Imaging Systems Corporation.
From the above measurements, it will be seen that the -dry developer formulated of the carrier of Example 1 and the .: .
toner of Example 2, in the amount of one part by weight of ton- .
er to lO0 parts by weight of carrier, yields a solid image.
The density at the center is high by comparison with the commercially available developers or any combinations be-tween components thereof with the carrier or toner of Examples 1 or 2. The improvement is significant, as further supported by the measurement ~D.
Thus, in accordance with the practice o this inven-tion, there is produced (1) a developer which makes use of a carrier that does not require a separate surface coating which otherwise subjects the carrier to degradation due to wear, chipping, and the like; (2) a developer which makes use of a carrier which has no tendency for toner particles to become im-pacted onto the surface; (3) a developer which gives improved solids development, possibly by reason of the fact that the carrier provides a highly conductive core in close proximity to the carrier surface, and (4) a developer which embodies a :-unique combination between the carrier and toner which further enhances the development of solid images and intensity of the copy that is produced.
It will be understood that changes may be made in th~
details of formulation, construction and operation without de-parting from the spirit of the invention, especially as defined 3 in the following claims:
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A dry electrophotographic developer comprising the mixture of uncoated carrier particles and finely divided toner in which the carrier consists essentially of particles of aluminum or alloys thereof of substantially spherical shape and a size within the range of 300-900 µ and having an oxidized surface and the toner comprises tinctorial agents and a binder in which an essential component of the binder is a styrene - butyl methacrylate copolymer and in which the tinctorial agent is present in an amount within the range of 5-30% by weight of the toner, and which optionally includes a solid lubricant and anti-caking agent.
2. A developer as claimed in Claim 1 in which the oxide surface on the carrier is an oxide layer which naturally forms on the aluminum.
3. A developer as claimed in Claim 1 in which the toner particles are of a size within the range of 2 to 20 microns.
4. A developer as claimed in Claim 1 in which the styrene - butyl methacrylate copolymer is present in an amount within the range of 50-85%
by weight of the toner.
by weight of the toner.
5. A developer as claimed in Claim 1 in which the styrene - butyl methacrylate copolymer is present in an amount within the range of 65-75%
by weight of the toner.
by weight of the toner.
6. A developer as claimed in Claim 1 in which the tinctorial agents are present in the toner in an amount within the range of 15-25% by weight.
7. A developer as claimed in Claim 1 in which, when present, the solid lubricant is in finely divided form and present in an amount up to 5% by weight.
8. A developer as claimed in Claims 1 and 7 in which the solid lubricant is present in an amount within the range of 0.2 - 2.0% by weight.
9. A developer as claimed in Claim 1 in which, when present, the anti-caking agent is present in an amount up to 1% by weight.
10. A developer as claimed in Claims 1 and 9 in which the anti-caking agent is present in an amount within the range of 0.1 - 1% by weight.
11. A developer as claimed in Claim 1 in which the toner and carrier are present in the mixture in an amount within the range of one part by weight of the toner to 40 to 200 parts by weight of the carrier.
12. A developer as claimed in Claims 1 and 11 in which the toner and carrier are present in the mixture in an amount within the range of one part by weight of the toner to 75 to 100 parts by weight of the carrier.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51332074A | 1974-10-09 | 1974-10-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062068A true CA1062068A (en) | 1979-09-11 |
Family
ID=24042762
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA235,750A Expired CA1062068A (en) | 1974-10-09 | 1975-09-18 | Dry electrophotographic developer |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5164933A (en) |
| BR (1) | BR7506550A (en) |
| CA (1) | CA1062068A (en) |
| DE (1) | DE2544659A1 (en) |
| GB (1) | GB1482395A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56142541A (en) * | 1980-04-09 | 1981-11-06 | Canon Inc | Manufacture of toner |
| JPS6247651A (en) * | 1985-08-27 | 1987-03-02 | Canon Inc | Image forming method |
-
1975
- 1975-09-18 CA CA235,750A patent/CA1062068A/en not_active Expired
- 1975-10-06 DE DE19752544659 patent/DE2544659A1/en active Pending
- 1975-10-07 BR BR7506550*A patent/BR7506550A/en unknown
- 1975-10-09 JP JP50121403A patent/JPS5164933A/ja active Pending
- 1975-10-09 GB GB41493/75A patent/GB1482395A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5164933A (en) | 1976-06-04 |
| GB1482395A (en) | 1977-08-10 |
| DE2544659A1 (en) | 1976-04-22 |
| BR7506550A (en) | 1976-08-17 |
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