CA1134662A - Styrene butadiene toner resins - Google Patents
Styrene butadiene toner resinsInfo
- Publication number
- CA1134662A CA1134662A CA000376296A CA376296A CA1134662A CA 1134662 A CA1134662 A CA 1134662A CA 000376296 A CA000376296 A CA 000376296A CA 376296 A CA376296 A CA 376296A CA 1134662 A CA1134662 A CA 1134662A
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- Canada
- Prior art keywords
- percent
- degrees fahrenheit
- toner
- toner composition
- temperature
- 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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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
- G03G9/087—Binders for toner particles
- G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- G03G9/08737—Polymers derived from conjugated dienes
-
- 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
- G03G9/087—Binders for toner particles
- G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- G03G9/08706—Polymers of alkenyl-aromatic compounds
- G03G9/08708—Copolymers of styrene
Abstract
ABSTRACT OF THE DISCLOSURE
This invention is directed generally to dry electrophotographic toner compositions comprised of a colorant and a styrene butadiene copolymer resin having a weight average molecular weight between about 60,000 and about 180,000 and a molecular weight distribution between about 5 and about 15, the percentage of styrene present ranging from about 80 percent to about 95 percent, with the percentage of butadiene present ranging from about 5 percent to about 20 percent, such toner having a minimum fixing temperature of from about 250 degrees Fahrenheit, to about 300 degrees Fahrenheit, and a fusing temperature latitude of at least 100 de-grees Fahrenheit.
This invention is directed generally to dry electrophotographic toner compositions comprised of a colorant and a styrene butadiene copolymer resin having a weight average molecular weight between about 60,000 and about 180,000 and a molecular weight distribution between about 5 and about 15, the percentage of styrene present ranging from about 80 percent to about 95 percent, with the percentage of butadiene present ranging from about 5 percent to about 20 percent, such toner having a minimum fixing temperature of from about 250 degrees Fahrenheit, to about 300 degrees Fahrenheit, and a fusing temperature latitude of at least 100 de-grees Fahrenheit.
Description
BACKGROUND OF THE INVENTION
This invention is generally directed to new developer compositions and the use of such developers for causing the development of images in an electrophotographic system. More specifically, the present invention is directed to positively charged toners comprised of styrene-butadiene copolymer type resins, which toners have broad temperature fusing latitudes, low minimum fix temperatures, and are particularly useful with hot roll fusing systems contained in electrophotographic imaging devices.
The electrophotographic process, and in particular, the xero-graphic process is well-known as described in numerous prior art references including many patents. In one sequence of the xerographic process the latent electrostatic image formed on the photoconductive surface is devel-oped with a variety of pigmented resin materials specifically made for this purpose, such as toner. Many processes are used for applying the electro-scopic particles or toners to the electrostatic latent image to be developed such as for example, the development method described in U.S. Patent 3,618,552, cascade development, U.S. Patent 2,874,063, and 3,357,402, magnetic brush development, U.S. Patent 2,221,776, powder cloud develop-ment, and U.S. Patent 3,166,432, touchdown development.
There are instances where it is desirable in electrophotographic systems to produce a reverse copy of the original, thus, for example, it may be desirable to produce a negative copy from a positive original, or a positive coW from negative original. This is referred to in the art as image reversal, and in electrostatic printing such image reversal can be accomplished by applying to the image a developer powder which is repelled by the charged areas of the image and adheres to the discharged areas.
Specifica~ly, toners possessing positive charges are found to be more useful and effective in electrophotographic reversal systems, and in particular, in electrophotographic systems employing organic photoreceptors, which in many instances are initially charged negatively rather than positively, thus necessitating the need for a positively charged toner. Reversal de-velopers are, for example, described in U.S. Patent 2,986,521.
In U.S. Patent 3,893,935 there is described the use of certain quaternary ammonium salts as useful charge control agents for electro-static toner compositions. According to the disclosure of this patent, certain quaternary ammonium salts when incorporated into toner materials 113~662 were found to provide a particulate toner composition, which exhibited relatively high uniform and stable net toner charge when mixed with a suitable carrier vehicle, and which toner also exhibited a minimum amount of toner throw-off. U.S. Patent 4,079,041 contains a similar teaching with the exception that a different charge control agent is used, namely a diazo type compound.
Several patents are in existence which disclose the use of styrene butadiene resins for use as toners in development systems, however, such patents do not teach the use of such resins of a particular composition and molecular weight for positively charged toners, and in particular for positive toners which have broad fusing latitudes for example. The patents involved include U.S. Patent 3,326,848 which discloses a toner of styrene butadiene copolymer, U .S. Patent 3,960,737 which discloses a liquid devel-oper of a mixture of styrene butadiene with an acrylate, U.S. Patent 3,766,072 ~, which discloses a developer containing at least two type~of particles, one of which can be a styrene butadiene type resin, (Pliolite S5D), Japanese Patent Publication 109483 and U.S. Patents 3,090,755 and 3,965,022.
Many of the above-described toners and developers do not have a broad fusing temperature latitude, described in detail hereinafter, nor a combination of low minimum fix temperatures and broad fusing temperature latitudes, without causing a decrease in the blocking temperature. Further some of the above-described developers have a tendency to lose their positive charge over a period of time, are difficult to prepare and in view of this the quality of the image that is to be developed is adversely affected.
Also the use of charge control agents and developers as described in U.S.
Patent 3,893, 935 are soluble in water causing them to be leeched to the toner surface by moisture thereby adversely affecting the machine en-vironment and the copy quality.
Accordingly, there is a need for developers which have broad fusing latitude temperature ranges, which toners can be used in hot roll fusing systems, these toners containing positive charges thereon and having low minimum fixing temperatures, that is, from about 250F to about 300F, and high blocking temperatures of from about 105 F to about 135 F.
SUMMARY OF THE INVENTION
It is an object of~this l~nvent~on to provide a toner which overcomes the above-noted disadvantages.
e It is an object of an aspect of this invention to provide a toner which has a broad fusing latitude temperature and can be used in hot roll fusing electrophoto-graphic systems.
An object of an aspect of this invention is the provision of a developer which contains positively charged toner comprised of a styrene butadiene copolymer resins.
An object of an aspect of this invention is to provide a developer which contains positively charged toner and a carrier material.
An object of an aspect of this invention is to provide toners which will develop electrostatic latent images containing negative charges on the photoreceptor surface and which will transfer effectively electrostatically from such a photoreceptor to plain bond paper without causing blurring or adversely affecting the quality of 'he resulting image.
An object of an aspect of the present invention is to provide a toner resin having additional fuse to hot offset temperature latitudes by increasing the resin molecular weight distribution.
An aspect of this invention is as follows:
An improved dry electrophotographic toner composition useful in electrophotographic imaging systems employing hot roll fusing, the toner composition consisting essentially of a colorant, a charge enhancing additive for imparting a positive charge to the toner composition, and an improved styrene butadiene copolymer resin having a weight average molecular weight of from between about 60,000 and about 180,000, and a molecular weight distribution of from about between 5 and 15, the percentage by weight of styrene present ranging from about 80 percent to about 95 percent, with the percentage by weight of butadiene present ranging from about 5 percent to about 20 percent, such toner having a minimum fixing temperature of from about 250 degrees Fahrenheit, r~ ~'`~
~ to about 300 degrees Fahrenheit, a fusing temperature 113~66Z
-3a-latitude of from about 105 degrees Fahrenheit to about 250 degrees Fahrenheit, and a blocking temperature of from about 105 degrees Fahrenheit to about 135 degrees Fahrenheit.
The percentage of styrene plus butadiene should total about lO0 percent, thus, when 90 percent of styrene is present in the copolymer resin, lO percent of butadiene is present. Preferred are styrene/butadiene resins containing 90 percent styrene and lO percent butadiene.
Many of the styrene/butadiene resins useful in the present invention include those commercially available from Goodyear Chemical Company, and known as Pliolite*, such as Pliolite S5A-E. Also embraced within the scope of the present invention are copolymers of vinyl toluene, with butadiene, the percentage of butadiene being present ranging from about 80 percent to about 95 percent, with the percentage of other monomer, (vinyl toluene) being from about 5 percent to about 20 percent.
* trade mark il3~6f~:
The amount of styrene butadiene copolymer resin present in the toner formulation ranges from about 80 percent to about 95 percent, and preferably from about 88 percent to about 94 percent based on the weight of toner, while the amount of colorant present ranges from between about 5 percent to about 20 percent and preferably from about 6 percent to about 12 percent. Thus, for example, when 85 percent of the styrene butadiene copolymer resin is present, 15 percent of the colorant is present.
By minimum fuse temperature is meant the temperature at which the toner is sufficiently melted, coalesced, and attached to a substrate, such as paper, so as to withstand conventional handling, filing, smearing, smudging, and/or loss of information, while the hot offset temperature, is the temperature at which the toner image splits internally with some of the toner remaining on the fuser roll. The fusing temperature latitude is the difference between the hot offset temperature, and the minimum fuse temperature, as reported in Example I.
Numerous suitable dyes or colorants may be employed together with the styrene butadiene resins for formulating the toner particles, such materials being well-known and including various types of carbon blacks, Nigrosine dye, aniline blue, chrome yellow, ultramarine blue, duPont oil red, phthalocyanine blue, and mixtures thereof with the preferred material being carbon black. The colorant should be present in the toner in sufficient quantity to render it highly colored so that it will form a visible image on the recording member. For example, where conventional xerographic copies of documents are desired the toner may comprise a black pigment such as carbon black. Also a black dye such as commercially available from National Aniline Products Inc. can be employed. Preferably the colorant is employed in amounts of from about 5 percent to about 20 percent by weight based on the total weight of toner.
As an additional ingredient there can be included in the toner composition of the present invention various additives, especially materials such as nigrosine and charge control additives, such as alkyl pyridinium compounds of the following formula:
A~ or ~ ~ A~ 2 R R
~134662 wherein R is an aliphatic radical such as methyl, ethyl, propyl, butyl, hexyl, octyl, nonyl and the like, and A is an anion such as chloride, bromide, fluoride, sulfate, sulfonate, phosphate, borate, and the like. The preferred additive is cetyl pyridinium chloride. The purpose of the charge control additive is to impart a positive charge to the toner resin.
The additive is present in amounts of from about 0.25 percent to about 4 percent, and preferably from about 0.5 percent to about 3 percent.
Several methods may be employed for producing the toner of the present invention, one such method involving melt blending the resin and the pigment followed by mechanical attrition. Other methods including those well-known in the art such as spray drying, melt dispersion and dis-persion polymerization. For example a solvent dispersion of resin and colorant are spray dryed under controlled conditions to result in the desired toner.
Such a toner produced in this manner results in a positive charged toner in relation to the carrier materials which are present when a developer is formulated, and these toners exhibit the improved properties as mentioned hereinbefore.
Any suitable carrier material can be employed with the toner of the present invention as long as such particles are capable of triboelec-trically obtaining a charge of opposite polarity to that of the toner particles.Toner plus carrier is referred to in the art as developer. In one embodiment in the present invention that would be a negative polarity to that of the toner particles which are positively charged so that the toner particles will adhere and surround the carrier particles. Accordingly, the carriers can be selected so that the toner particles require a charge of positive polarity and include inorganic materials, organic materials, as well as coated carriers, including for example, sodium chloride, ammonium chloride, ammonium potassium chloride, aluminum nitrate, granular zinc, granular silicone, methyl methacrylate, glass, steel, nickel, iron ferrite, silicone dioxide, and the like. Coated carriers that may be used include the above-mentioned carriers coated for example with organic materials such as fluorinated polymers including polyvinylidene fluoride. Many of the carriers that can be used are described in U.S. Patents 2,618,441; 2,638,416; 3,591,503;
3,533,835 and 3,526,533. Also nickel berry carriers as described in U.S.
Patents 3,847,604 and 3,767,598 can be employed. These carriers being nodular beads of nickel characterized by surfaces of recurring recesses and protrusions, provide particles with a relatively large external area.
113~66~:
The diameter of the coated carrier particle is from about 50 to about 1,000 microns thus allowing the carrier to possess sufficient density and inertia to avoid adherence to the electrostatic images during the development process.
The carrier may be employed with the toner composition in any suitable combination, however, best results are obtained when about 1 part per toner is used and about 10 to about 200 parts per weight of carrier.
Toners of the present invention may be used to develop electro-static latent images on any suitable electrostatic surface capable of re-10 taining charge including conventional photoconductors, however, the toners of the present invention are best utilized in systems wherein a neg-ative charge resides on the photoreceptor and this usually occurs with organic photoreceptors. Illustrative examples of such photoreceptors include poly-vinyl carbazole, 4-dimethylamino benzylidene, benzhydrazide, 2-benzyli-15 deneamino-carbazole, 4-dimethylamino-benzylidene, benzhydrazide, 2-benzylidene-amino-carbazole, polyvinylcarbazole substituted materials, (2-nitrobenzylidene~p-amino aniline, 2,4-diphenyl-quinazoline, 1,2,4-tri-azine, 1,5diphenyl-3-methyl pyrazoline, 2-(4'-dimethyl amino phenyl~benz-oxazole, 3-amino carbazole, polyvinyl carbazole-trinitrofluorenone charge 20 transfer complexes, phthalocyanines and mixtures thereof.
The following examples are being supplied to further define the species of the present invention, it being noted that these examples are intended to illustrate and not limit the scope of the present invention.
Parts and percentages are by weight unless otherwise indicated.
Minimum fix was evaluated by subjecting the image to be tested which has a fused solid area optical density of 1.2--0.1, as measured by a Macbeth Model RD517 optical densitometer, to ten cycles of abrasive action on a Teledyne Tabor Abrader Model 503, using #10 wheels and a load of 1,000 grams of weight. The abraded images were then compared 30 to standard images representing various degrees of fix to assess fix on a letter scale from A (best) to D (worst), based on the visual comparison of the image relative to the standard. The standard images were derived from a survey taken with Xerox 9200 images intentionally fused to a range of levels. Fix for the PlioliteR resins was excellent (A) while the fix for 35 the polyester resins, reference Example I, were not of high quality, (C).
Also, in the following examples, hot offset temperature was measured by attaching a trailing piece of white paper to the image so that any toner offset to the fuser roll would print back on the trailing sheet on the subsequent roII revolution. Offset was defined as the appearance of toner anywhere on the trailing sheet.
Temperatures on the fuser roll were measured using an iron constantan thermocouple in contact with the fusing surface and confirmed using a Barnes infared radiometer.
Images using the toner resins of the following examples were made using a Xerox Model DR flat plate apparatus and a steel carrier.
10 These images were then evaluated for minimum fix and hot offset on a test fixture comprised of a 3 inch diameter internally heated silicone rubber coated fuser roll and a 3 inch diameter TeflonR coated back up roll. The rolls were loaded to form a nip of 0.21 inches and operated at a surface speed of 10 inches/sec. The silicone rubber coating the fuser roll was a 15 high temperature vulcanized silicone rubber 70 mils thick.
Toner mechanical requirements for minimum fix and hot offset are incompatible in one respect; a good toner from a fix standpoint is one that softens rapidly with increasing temperature, and flows readily under relatively low pressures (40 to 200 PSI (pounds per square inch) ) encounter-20 ed in the fusing nip, while a good toner for hot offset is one that is relatively temperature insensitive with respect to softening, and one that can support the stresses during release from the fuser roll (7 to 70 PSI), without failing internally and creating hot offset. Thus, the ideal toner exhibits a high modulus at room temperature ( > 400 PSI), which decreases rapidly with 25 increasing temperature to the range of 14-140 PSI (where minimum fix occurs), and which abruptly levels off to form a plateau region where the modulus becomes relatively temperature insensitive. Such plateau is known in the art as the "rubbery plateau" region and it should extend over as broad a temperature range as possible for maximum latitude.
Another toner mechanical requirement concerns the rate of softening of the toner from room temperature to about 130 F. While rapid softening of the toner is desirable for low minimum fix temperatures, it is also desirable that the toner remain rigid at temperatures below 130 F
to prevent caking during transport and storage. The temperature where 35 caking appears within a twenty four hour period is called the blocking tem-perature and is correlated to the glass transition temperature, a well known rheological property. It has been experimentally observed (see "The Viscosity of Polymers and Their Concentrated Solutions", by G. C. Berry and T. G.
Fox in Advances in Polymer Science, Volume 5, Pages 261-357, (1968)), that for a given glass transition temperature, polymer families exhibiting the lowest polarity exhibit the lowest viscosity at elevated temperatures and thus might be expected to have the lowest minimum fix temperatures.
By this criteria, styrene butadienes are excellent resins for toners because of their low polarity relative to other toner resins, such as the styrene methacrylate family.
One object of the present invention is to obtain a broad molecular weight distribution to extend the fusing latitude through an extension of the rubbery plateau. A broad molecular weight distribution can be obtained either during polymerization or by blending two or more resins after poly-merization. Typically, a polymer will have a molecular weight distribution (Mw) in the range of 2-4, where Mw = weight average molecular weight (Mn) Mn number average molecular weight.
The styrene butadiene copolymers of the present application have molecular weight distributions in the range of 5 to 15, thereby resulting in the im-proved toners of the present application. Better fusing behavior would be achieved using still broader molecular weight distributions but the prep-0 aration of such materials becomes increasingly difficult for molecular weight distributions above about 10.
EXAMPLE I
A toner was prepared comprising 10 percent of a carbon black, e commercially available as Raven~5250, and 90 percent of a styrene buta-diene copolymer comprised of 90 percent styrene and 10 percent butadiene, having a weight average molecular weight of 163,000 (MMW = 8.9), and commercially available from Goodyear Corporation as Pliolite S5A, by melt blending followed by mechanical attrition. Other toners were prepared in a similar manner, and these toners were subjected to fusing experiments using a conformable fuser roll with the following results.
f r.6 11346~X, g Toner Minimum Fuse Hot Offset Fusing Blocking Temp. Temp. Temp Temp.
Pliolite* 290F > 540F > 250F 120F
10% Raven Pliolite* 300 F 455 F 155 F 120 F
10% Raven Pliolite* 300F 420F 120F 115F to 10 Vinyl 120 F
Toluene Copolymer 10% Raven *Commercially available from Goodyear Chemical Company.
15 Comparative experiments were also accomplished with a con-formable fuser roll using toners from different resins that is, resins other than styrene butadiene with the following results:
Toner Minimum Fuse Hot Offset Fusing Blocking Temp. Temp. Temp. Temp.
Latitude 20 Linear 280 p 302 F 20 F 110 F
Polyester Resin +10% BPL*
Branched 270 F 350 F 80 F 110-115 F
Polyester Resin 25 +10% BPL*
Branched 290 F 265 F 75 F 105-110 F
Polyester Resin +10% BPL*
Styrene/ 350 F 450 F 100 F 120 F
n-butyl 30 Methacrylate Copolymer resin 65/35, 82% carbon Black, 9%
Polyvinylbutyral, 9%
*BPL = Black Pearls (carbon black) commercially available EXAMPLE II
There was prepared by melt blending followed by mechanical attrition a toner comprised of 89.5 percent of Pliolite S5E, commercially - lo -available from Goodyear Chemical, and containing 90 percent styrene, l0 percent butadiene; 0.5 percent nigrosine, and 10 percent of carbon black, Raven 420, commercially available from Citgo. This toner after being sub-jected to the minimum fix and hot offset tests in accordance with Example I resulted in the following:
Minimum fix temperature 275 F
Hot offset temperature 415 F
Fusing latitude temperature 140 F
Blocking temperature 115 F
The quality of fix was excellent, and on a scale of from A (best) to D (worst), the level of fix was A.
EXAMPLE III
The procedure of Example n was repeated with the exception that the Pliolite resin used was comprised of 89 percent styrene, ll percent 15 butadiene. The toner of this example had a minimum fix temperature of 300 F, a hot offset temperature of 380 F, a fusing latitude temperature of 105 F, and a blocking temperature of 120 F.
EXAMPLE IV
The procedure of Example II was repeated with the exception 20 that 88 percent of the Pliolite resin of Example III, was mixed with 10 percent of the carbon black and two percent Nigrosine. The toner of this example had a minimum fix temperature of 260F, a hot offset temperature of 375F, and a fusing latitude temperature of U5 F.
EXAMPLE V
Each of the toner resins of Examples I-IV, l part by weight, were mixed with 50 parts by weight of a steel carrier, resulting in developing com-positions.
These developer compositions when used in a xerographic imaging fixture, the Xerox Model D flat plate apparatus, produced acceptable images.
30 as defined herein.
Other modifications of the present invention will occur to those skilled in the art upon a reading of the present invention. These are intended to be included within the scope of this invention.
This invention is generally directed to new developer compositions and the use of such developers for causing the development of images in an electrophotographic system. More specifically, the present invention is directed to positively charged toners comprised of styrene-butadiene copolymer type resins, which toners have broad temperature fusing latitudes, low minimum fix temperatures, and are particularly useful with hot roll fusing systems contained in electrophotographic imaging devices.
The electrophotographic process, and in particular, the xero-graphic process is well-known as described in numerous prior art references including many patents. In one sequence of the xerographic process the latent electrostatic image formed on the photoconductive surface is devel-oped with a variety of pigmented resin materials specifically made for this purpose, such as toner. Many processes are used for applying the electro-scopic particles or toners to the electrostatic latent image to be developed such as for example, the development method described in U.S. Patent 3,618,552, cascade development, U.S. Patent 2,874,063, and 3,357,402, magnetic brush development, U.S. Patent 2,221,776, powder cloud develop-ment, and U.S. Patent 3,166,432, touchdown development.
There are instances where it is desirable in electrophotographic systems to produce a reverse copy of the original, thus, for example, it may be desirable to produce a negative copy from a positive original, or a positive coW from negative original. This is referred to in the art as image reversal, and in electrostatic printing such image reversal can be accomplished by applying to the image a developer powder which is repelled by the charged areas of the image and adheres to the discharged areas.
Specifica~ly, toners possessing positive charges are found to be more useful and effective in electrophotographic reversal systems, and in particular, in electrophotographic systems employing organic photoreceptors, which in many instances are initially charged negatively rather than positively, thus necessitating the need for a positively charged toner. Reversal de-velopers are, for example, described in U.S. Patent 2,986,521.
In U.S. Patent 3,893,935 there is described the use of certain quaternary ammonium salts as useful charge control agents for electro-static toner compositions. According to the disclosure of this patent, certain quaternary ammonium salts when incorporated into toner materials 113~662 were found to provide a particulate toner composition, which exhibited relatively high uniform and stable net toner charge when mixed with a suitable carrier vehicle, and which toner also exhibited a minimum amount of toner throw-off. U.S. Patent 4,079,041 contains a similar teaching with the exception that a different charge control agent is used, namely a diazo type compound.
Several patents are in existence which disclose the use of styrene butadiene resins for use as toners in development systems, however, such patents do not teach the use of such resins of a particular composition and molecular weight for positively charged toners, and in particular for positive toners which have broad fusing latitudes for example. The patents involved include U.S. Patent 3,326,848 which discloses a toner of styrene butadiene copolymer, U .S. Patent 3,960,737 which discloses a liquid devel-oper of a mixture of styrene butadiene with an acrylate, U.S. Patent 3,766,072 ~, which discloses a developer containing at least two type~of particles, one of which can be a styrene butadiene type resin, (Pliolite S5D), Japanese Patent Publication 109483 and U.S. Patents 3,090,755 and 3,965,022.
Many of the above-described toners and developers do not have a broad fusing temperature latitude, described in detail hereinafter, nor a combination of low minimum fix temperatures and broad fusing temperature latitudes, without causing a decrease in the blocking temperature. Further some of the above-described developers have a tendency to lose their positive charge over a period of time, are difficult to prepare and in view of this the quality of the image that is to be developed is adversely affected.
Also the use of charge control agents and developers as described in U.S.
Patent 3,893, 935 are soluble in water causing them to be leeched to the toner surface by moisture thereby adversely affecting the machine en-vironment and the copy quality.
Accordingly, there is a need for developers which have broad fusing latitude temperature ranges, which toners can be used in hot roll fusing systems, these toners containing positive charges thereon and having low minimum fixing temperatures, that is, from about 250F to about 300F, and high blocking temperatures of from about 105 F to about 135 F.
SUMMARY OF THE INVENTION
It is an object of~this l~nvent~on to provide a toner which overcomes the above-noted disadvantages.
e It is an object of an aspect of this invention to provide a toner which has a broad fusing latitude temperature and can be used in hot roll fusing electrophoto-graphic systems.
An object of an aspect of this invention is the provision of a developer which contains positively charged toner comprised of a styrene butadiene copolymer resins.
An object of an aspect of this invention is to provide a developer which contains positively charged toner and a carrier material.
An object of an aspect of this invention is to provide toners which will develop electrostatic latent images containing negative charges on the photoreceptor surface and which will transfer effectively electrostatically from such a photoreceptor to plain bond paper without causing blurring or adversely affecting the quality of 'he resulting image.
An object of an aspect of the present invention is to provide a toner resin having additional fuse to hot offset temperature latitudes by increasing the resin molecular weight distribution.
An aspect of this invention is as follows:
An improved dry electrophotographic toner composition useful in electrophotographic imaging systems employing hot roll fusing, the toner composition consisting essentially of a colorant, a charge enhancing additive for imparting a positive charge to the toner composition, and an improved styrene butadiene copolymer resin having a weight average molecular weight of from between about 60,000 and about 180,000, and a molecular weight distribution of from about between 5 and 15, the percentage by weight of styrene present ranging from about 80 percent to about 95 percent, with the percentage by weight of butadiene present ranging from about 5 percent to about 20 percent, such toner having a minimum fixing temperature of from about 250 degrees Fahrenheit, r~ ~'`~
~ to about 300 degrees Fahrenheit, a fusing temperature 113~66Z
-3a-latitude of from about 105 degrees Fahrenheit to about 250 degrees Fahrenheit, and a blocking temperature of from about 105 degrees Fahrenheit to about 135 degrees Fahrenheit.
The percentage of styrene plus butadiene should total about lO0 percent, thus, when 90 percent of styrene is present in the copolymer resin, lO percent of butadiene is present. Preferred are styrene/butadiene resins containing 90 percent styrene and lO percent butadiene.
Many of the styrene/butadiene resins useful in the present invention include those commercially available from Goodyear Chemical Company, and known as Pliolite*, such as Pliolite S5A-E. Also embraced within the scope of the present invention are copolymers of vinyl toluene, with butadiene, the percentage of butadiene being present ranging from about 80 percent to about 95 percent, with the percentage of other monomer, (vinyl toluene) being from about 5 percent to about 20 percent.
* trade mark il3~6f~:
The amount of styrene butadiene copolymer resin present in the toner formulation ranges from about 80 percent to about 95 percent, and preferably from about 88 percent to about 94 percent based on the weight of toner, while the amount of colorant present ranges from between about 5 percent to about 20 percent and preferably from about 6 percent to about 12 percent. Thus, for example, when 85 percent of the styrene butadiene copolymer resin is present, 15 percent of the colorant is present.
By minimum fuse temperature is meant the temperature at which the toner is sufficiently melted, coalesced, and attached to a substrate, such as paper, so as to withstand conventional handling, filing, smearing, smudging, and/or loss of information, while the hot offset temperature, is the temperature at which the toner image splits internally with some of the toner remaining on the fuser roll. The fusing temperature latitude is the difference between the hot offset temperature, and the minimum fuse temperature, as reported in Example I.
Numerous suitable dyes or colorants may be employed together with the styrene butadiene resins for formulating the toner particles, such materials being well-known and including various types of carbon blacks, Nigrosine dye, aniline blue, chrome yellow, ultramarine blue, duPont oil red, phthalocyanine blue, and mixtures thereof with the preferred material being carbon black. The colorant should be present in the toner in sufficient quantity to render it highly colored so that it will form a visible image on the recording member. For example, where conventional xerographic copies of documents are desired the toner may comprise a black pigment such as carbon black. Also a black dye such as commercially available from National Aniline Products Inc. can be employed. Preferably the colorant is employed in amounts of from about 5 percent to about 20 percent by weight based on the total weight of toner.
As an additional ingredient there can be included in the toner composition of the present invention various additives, especially materials such as nigrosine and charge control additives, such as alkyl pyridinium compounds of the following formula:
A~ or ~ ~ A~ 2 R R
~134662 wherein R is an aliphatic radical such as methyl, ethyl, propyl, butyl, hexyl, octyl, nonyl and the like, and A is an anion such as chloride, bromide, fluoride, sulfate, sulfonate, phosphate, borate, and the like. The preferred additive is cetyl pyridinium chloride. The purpose of the charge control additive is to impart a positive charge to the toner resin.
The additive is present in amounts of from about 0.25 percent to about 4 percent, and preferably from about 0.5 percent to about 3 percent.
Several methods may be employed for producing the toner of the present invention, one such method involving melt blending the resin and the pigment followed by mechanical attrition. Other methods including those well-known in the art such as spray drying, melt dispersion and dis-persion polymerization. For example a solvent dispersion of resin and colorant are spray dryed under controlled conditions to result in the desired toner.
Such a toner produced in this manner results in a positive charged toner in relation to the carrier materials which are present when a developer is formulated, and these toners exhibit the improved properties as mentioned hereinbefore.
Any suitable carrier material can be employed with the toner of the present invention as long as such particles are capable of triboelec-trically obtaining a charge of opposite polarity to that of the toner particles.Toner plus carrier is referred to in the art as developer. In one embodiment in the present invention that would be a negative polarity to that of the toner particles which are positively charged so that the toner particles will adhere and surround the carrier particles. Accordingly, the carriers can be selected so that the toner particles require a charge of positive polarity and include inorganic materials, organic materials, as well as coated carriers, including for example, sodium chloride, ammonium chloride, ammonium potassium chloride, aluminum nitrate, granular zinc, granular silicone, methyl methacrylate, glass, steel, nickel, iron ferrite, silicone dioxide, and the like. Coated carriers that may be used include the above-mentioned carriers coated for example with organic materials such as fluorinated polymers including polyvinylidene fluoride. Many of the carriers that can be used are described in U.S. Patents 2,618,441; 2,638,416; 3,591,503;
3,533,835 and 3,526,533. Also nickel berry carriers as described in U.S.
Patents 3,847,604 and 3,767,598 can be employed. These carriers being nodular beads of nickel characterized by surfaces of recurring recesses and protrusions, provide particles with a relatively large external area.
113~66~:
The diameter of the coated carrier particle is from about 50 to about 1,000 microns thus allowing the carrier to possess sufficient density and inertia to avoid adherence to the electrostatic images during the development process.
The carrier may be employed with the toner composition in any suitable combination, however, best results are obtained when about 1 part per toner is used and about 10 to about 200 parts per weight of carrier.
Toners of the present invention may be used to develop electro-static latent images on any suitable electrostatic surface capable of re-10 taining charge including conventional photoconductors, however, the toners of the present invention are best utilized in systems wherein a neg-ative charge resides on the photoreceptor and this usually occurs with organic photoreceptors. Illustrative examples of such photoreceptors include poly-vinyl carbazole, 4-dimethylamino benzylidene, benzhydrazide, 2-benzyli-15 deneamino-carbazole, 4-dimethylamino-benzylidene, benzhydrazide, 2-benzylidene-amino-carbazole, polyvinylcarbazole substituted materials, (2-nitrobenzylidene~p-amino aniline, 2,4-diphenyl-quinazoline, 1,2,4-tri-azine, 1,5diphenyl-3-methyl pyrazoline, 2-(4'-dimethyl amino phenyl~benz-oxazole, 3-amino carbazole, polyvinyl carbazole-trinitrofluorenone charge 20 transfer complexes, phthalocyanines and mixtures thereof.
The following examples are being supplied to further define the species of the present invention, it being noted that these examples are intended to illustrate and not limit the scope of the present invention.
Parts and percentages are by weight unless otherwise indicated.
Minimum fix was evaluated by subjecting the image to be tested which has a fused solid area optical density of 1.2--0.1, as measured by a Macbeth Model RD517 optical densitometer, to ten cycles of abrasive action on a Teledyne Tabor Abrader Model 503, using #10 wheels and a load of 1,000 grams of weight. The abraded images were then compared 30 to standard images representing various degrees of fix to assess fix on a letter scale from A (best) to D (worst), based on the visual comparison of the image relative to the standard. The standard images were derived from a survey taken with Xerox 9200 images intentionally fused to a range of levels. Fix for the PlioliteR resins was excellent (A) while the fix for 35 the polyester resins, reference Example I, were not of high quality, (C).
Also, in the following examples, hot offset temperature was measured by attaching a trailing piece of white paper to the image so that any toner offset to the fuser roll would print back on the trailing sheet on the subsequent roII revolution. Offset was defined as the appearance of toner anywhere on the trailing sheet.
Temperatures on the fuser roll were measured using an iron constantan thermocouple in contact with the fusing surface and confirmed using a Barnes infared radiometer.
Images using the toner resins of the following examples were made using a Xerox Model DR flat plate apparatus and a steel carrier.
10 These images were then evaluated for minimum fix and hot offset on a test fixture comprised of a 3 inch diameter internally heated silicone rubber coated fuser roll and a 3 inch diameter TeflonR coated back up roll. The rolls were loaded to form a nip of 0.21 inches and operated at a surface speed of 10 inches/sec. The silicone rubber coating the fuser roll was a 15 high temperature vulcanized silicone rubber 70 mils thick.
Toner mechanical requirements for minimum fix and hot offset are incompatible in one respect; a good toner from a fix standpoint is one that softens rapidly with increasing temperature, and flows readily under relatively low pressures (40 to 200 PSI (pounds per square inch) ) encounter-20 ed in the fusing nip, while a good toner for hot offset is one that is relatively temperature insensitive with respect to softening, and one that can support the stresses during release from the fuser roll (7 to 70 PSI), without failing internally and creating hot offset. Thus, the ideal toner exhibits a high modulus at room temperature ( > 400 PSI), which decreases rapidly with 25 increasing temperature to the range of 14-140 PSI (where minimum fix occurs), and which abruptly levels off to form a plateau region where the modulus becomes relatively temperature insensitive. Such plateau is known in the art as the "rubbery plateau" region and it should extend over as broad a temperature range as possible for maximum latitude.
Another toner mechanical requirement concerns the rate of softening of the toner from room temperature to about 130 F. While rapid softening of the toner is desirable for low minimum fix temperatures, it is also desirable that the toner remain rigid at temperatures below 130 F
to prevent caking during transport and storage. The temperature where 35 caking appears within a twenty four hour period is called the blocking tem-perature and is correlated to the glass transition temperature, a well known rheological property. It has been experimentally observed (see "The Viscosity of Polymers and Their Concentrated Solutions", by G. C. Berry and T. G.
Fox in Advances in Polymer Science, Volume 5, Pages 261-357, (1968)), that for a given glass transition temperature, polymer families exhibiting the lowest polarity exhibit the lowest viscosity at elevated temperatures and thus might be expected to have the lowest minimum fix temperatures.
By this criteria, styrene butadienes are excellent resins for toners because of their low polarity relative to other toner resins, such as the styrene methacrylate family.
One object of the present invention is to obtain a broad molecular weight distribution to extend the fusing latitude through an extension of the rubbery plateau. A broad molecular weight distribution can be obtained either during polymerization or by blending two or more resins after poly-merization. Typically, a polymer will have a molecular weight distribution (Mw) in the range of 2-4, where Mw = weight average molecular weight (Mn) Mn number average molecular weight.
The styrene butadiene copolymers of the present application have molecular weight distributions in the range of 5 to 15, thereby resulting in the im-proved toners of the present application. Better fusing behavior would be achieved using still broader molecular weight distributions but the prep-0 aration of such materials becomes increasingly difficult for molecular weight distributions above about 10.
EXAMPLE I
A toner was prepared comprising 10 percent of a carbon black, e commercially available as Raven~5250, and 90 percent of a styrene buta-diene copolymer comprised of 90 percent styrene and 10 percent butadiene, having a weight average molecular weight of 163,000 (MMW = 8.9), and commercially available from Goodyear Corporation as Pliolite S5A, by melt blending followed by mechanical attrition. Other toners were prepared in a similar manner, and these toners were subjected to fusing experiments using a conformable fuser roll with the following results.
f r.6 11346~X, g Toner Minimum Fuse Hot Offset Fusing Blocking Temp. Temp. Temp Temp.
Pliolite* 290F > 540F > 250F 120F
10% Raven Pliolite* 300 F 455 F 155 F 120 F
10% Raven Pliolite* 300F 420F 120F 115F to 10 Vinyl 120 F
Toluene Copolymer 10% Raven *Commercially available from Goodyear Chemical Company.
15 Comparative experiments were also accomplished with a con-formable fuser roll using toners from different resins that is, resins other than styrene butadiene with the following results:
Toner Minimum Fuse Hot Offset Fusing Blocking Temp. Temp. Temp. Temp.
Latitude 20 Linear 280 p 302 F 20 F 110 F
Polyester Resin +10% BPL*
Branched 270 F 350 F 80 F 110-115 F
Polyester Resin 25 +10% BPL*
Branched 290 F 265 F 75 F 105-110 F
Polyester Resin +10% BPL*
Styrene/ 350 F 450 F 100 F 120 F
n-butyl 30 Methacrylate Copolymer resin 65/35, 82% carbon Black, 9%
Polyvinylbutyral, 9%
*BPL = Black Pearls (carbon black) commercially available EXAMPLE II
There was prepared by melt blending followed by mechanical attrition a toner comprised of 89.5 percent of Pliolite S5E, commercially - lo -available from Goodyear Chemical, and containing 90 percent styrene, l0 percent butadiene; 0.5 percent nigrosine, and 10 percent of carbon black, Raven 420, commercially available from Citgo. This toner after being sub-jected to the minimum fix and hot offset tests in accordance with Example I resulted in the following:
Minimum fix temperature 275 F
Hot offset temperature 415 F
Fusing latitude temperature 140 F
Blocking temperature 115 F
The quality of fix was excellent, and on a scale of from A (best) to D (worst), the level of fix was A.
EXAMPLE III
The procedure of Example n was repeated with the exception that the Pliolite resin used was comprised of 89 percent styrene, ll percent 15 butadiene. The toner of this example had a minimum fix temperature of 300 F, a hot offset temperature of 380 F, a fusing latitude temperature of 105 F, and a blocking temperature of 120 F.
EXAMPLE IV
The procedure of Example II was repeated with the exception 20 that 88 percent of the Pliolite resin of Example III, was mixed with 10 percent of the carbon black and two percent Nigrosine. The toner of this example had a minimum fix temperature of 260F, a hot offset temperature of 375F, and a fusing latitude temperature of U5 F.
EXAMPLE V
Each of the toner resins of Examples I-IV, l part by weight, were mixed with 50 parts by weight of a steel carrier, resulting in developing com-positions.
These developer compositions when used in a xerographic imaging fixture, the Xerox Model D flat plate apparatus, produced acceptable images.
30 as defined herein.
Other modifications of the present invention will occur to those skilled in the art upon a reading of the present invention. These are intended to be included within the scope of this invention.
Claims (9)
1. An improved dry electrophotographic toner composition useful in electrophotographic imaging systems employing hot roll fusing, the toner composition consisting essentially of a colorant, a charge enhancing additive for imparting a positive charge to the toner composition, and an improved styrene butadiene copolymer resin having a weight average molecular weight of from between about 60,000 and about 180,000, and a molecular weight distribution of from about between 5 and 15, the percentage by weight of styrene present ranging from about 80 percent to about 95 percent, with the percentage by weight of butadiene present ranging from about 5 percent to about 20 percent, such toner having a minimum fixing temperature of from about 250 degrees Fahrenheit, to about 300 degrees Fahrenheit a fusing temperature latitude of from about 105 degrees Fahrenheit to about 250 degrees Fahrenheit, and a blocking temperature of from about 105 degrees Fahrenheit to about 135 degrees Fahrenheit.
2. An improved toner composition in accordance with Claim 1 wherein the molecular weight distribution of the styrene butadiene resin is about 9, and the average molecular weight is about 160,000.
3. An improved toner composition in accordance with Claim 1 wherein the styrene butadiene resin employed has a minimum fixing temperature of 275 degrees Fahrenheit, a blocking temperature of 135 degrees Fahrenheit, and a fusing temperature latitude of 140 degrees Fahrenheit.
4. An improved toner composition in accordance with Claim 1 wherein the styrene butadiene resin employed has a minimum fixing temperature of 300 degrees Fahrenheit, a blocking temperature of 135 degrees Fahrenheit, and a fusing temperature latitude of 105 degrees Fahrenheit.
5. An improved toner composition in accordance with Claim 1 wherein the additive material is cetyl pyridinium chloride.
6. An improved toner composition in accordance with Claim 1 wherein the amount of colorant present ranges from about 5 percent to about 20 percent by weight, and the amount of styrene butadiene copolymer resin present ranges from about 80 percent to about 95 percent by weight.
7. An improved toner in accordance with Claim 1 wherein the colorant is carbon black, and the styrene butadiene resin contains 90 percent styrene by weight, and 10 percent butadiene by weight.
8. An improved toner composition in accordance with Claim 1 wherein there is added as an additional ingredient a carrier material.
9. An improved toner composition in accordance with Claim 8 wherein the carrier is steel coated with a fluorinated polymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14885580A | 1980-05-12 | 1980-05-12 | |
| US148,855 | 1980-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1134662A true CA1134662A (en) | 1982-11-02 |
Family
ID=22527715
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376296A Expired CA1134662A (en) | 1980-05-12 | 1981-04-27 | Styrene butadiene toner resins |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS575052A (en) |
| CA (1) | CA1134662A (en) |
| DE (1) | DE3118608A1 (en) |
| GB (1) | GB2075703A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0820760B2 (en) * | 1987-01-27 | 1996-03-04 | 三井東圧化学株式会社 | Electrophotographic toner composition |
| CA1329718C (en) * | 1987-08-03 | 1994-05-24 | John R. Laing | Developer compositions with suspension polymerized styrene butadiene resins |
| JPH0380260A (en) * | 1989-08-24 | 1991-04-05 | Sanyo Chem Ind Ltd | Resin composition for toner for electrophotography |
| JPH0812481B2 (en) * | 1989-11-25 | 1996-02-07 | 三洋化成工業株式会社 | Toner binder for electrophotography |
| JPH03274576A (en) * | 1990-03-26 | 1991-12-05 | Sanyo Chem Ind Ltd | Electrophotographic toner binder |
| US5206319A (en) * | 1991-08-19 | 1993-04-27 | Mitsui Toatsu Chemicals, Inc. | Process for preparing a toner resin, toner resin prepared thereby and toner composition containing particles of the toner resin |
| US5298356A (en) * | 1992-11-13 | 1994-03-29 | Eastman Kodak Company | Toner composition with elastomeric thermoplastic polymer and process of preparing |
| US5298355A (en) * | 1992-11-13 | 1994-03-29 | Eastman Kodak Company | Toner composition with semi-crystalline polyester wax and method of preparation |
| US5912097A (en) * | 1993-07-06 | 1999-06-15 | Eastman Kodak Company | Electrostatographic method using an overlay toner |
| US5462829A (en) * | 1993-12-21 | 1995-10-31 | Eastman Kodak Company | Polymer blends and toner compositions comprising same |
| DE4405256A1 (en) * | 1994-02-18 | 1995-08-24 | Buna Gmbh | Recycled plastic molding compound |
-
1981
- 1981-04-27 CA CA000376296A patent/CA1134662A/en not_active Expired
- 1981-05-06 JP JP6804781A patent/JPS575052A/en active Pending
- 1981-05-11 DE DE19813118608 patent/DE3118608A1/en not_active Withdrawn
- 1981-05-12 GB GB8114436A patent/GB2075703A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE3118608A1 (en) | 1982-05-06 |
| GB2075703A (en) | 1981-11-18 |
| JPS575052A (en) | 1982-01-11 |
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