Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-04-18
2001-02-06
Stockton, Laura L. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C546S198000, C548S159000
Reexamination Certificate
active
06184387
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electrostatographic developers and toners containing charge-control agents.
BACKGROUND OF THE INVENTION
In electrography, image charge patterns are formed on a support and are developed by treatment with an electrographic developer containing marking particles which are attracted to the charge patterns. These particles are called toner particles or, collectively, toner. Two major types of developers, dry and liquid, are employed in the development of the charge patterns.
In electrostatography, the image charge pattern, also referred to as an electrostatic latent image, is formed on an insulative surface of an electrostatographic element by any of a variety of methods. For example, the electrostatic latent image may be formed electrophotographically, by imagewise photo-induced dissipation of the strength of portions of an electrostatic field of uniform strength previously formed on the surface of an electrophotographic element comprising a photoconductive layer and an electrically conductive substrate. Alternatively, the electrostatic latent image may be formed by direct electrical formation of an electrostatic field pattern on a surface of a dielectric material.
One well-known type of electrostatographic developer comprises a dry mixture of toner particles and carrier particles. Developers of this type are employed in cascade and magnetic brush electrostatographic development processes. The toner particles and carrier particles differ triboelectrically, such that during mixing to form the developer, the toner particles acquire a charge of one polarity and the carrier particles acquire a charge of the opposite polarity. The opposite charges cause the toner particles to cling to the carrier particles. During development, the electrostatic forces of the latent image, sometimes in combination with an additional applied field, attract the toner particles. The toner particles are pulled away from the carrier particles and become electrostatically attached, in imagewise relation, to the latent image bearing surface. The resultant toner image can then be fixed, by application of heat or other known methods, depending upon the nature of the toner image and the surface, or can be transferred to another surface and then fixed.
Toner particles often include charge control agents that desirably, provide uniform net electrical charge to toner particles without reducing the adhesion of the toner to paper or other medium. Many types of positive charge control agents, materials which impart a positive charge to toner particles in a developer, have been used and are described in the published patent literature. In contrast, relatively few negative charge control agents, materials which impart a negative charge to toner particles in a developer, are known.
Prior negative charge-control agents have a variety of shortcomings. Many charge-control agents are dark colored and cannot be readily used-with pigmented toners, such as cyan, magenta, yellow, red, blue, and green. Some are highly toxic or produce highly toxic by-products. Some are highly sensitive to environmental conditions such as humidity. Some exhibit high throw-off or adverse triboelectric properties in some uses. Use of charge-control agents requires a balancing of shortcomings and desired characteristics to meet a particular situation.
The prior art discloses the use of 1,2-benzisothiazol-3(2H)-ylidene 1,1-dioxides as negative charge control agents for electrophotographic toners and developers. The general structural formula for this class of compounds is represented as:
Such compounds are disclosed in U.S. Pat. Nos. 5,744,277, 5,719,001, 5,976,753, 5,821,025, 5,766,815, 5,714,295, 5,716,749, 5,750,715, 5,719,000, 5,723,249, 5,821,024, 5,922,499, and 5,739,235.
Of these disclosures, U.S. Pat. No. 5,922,499 is particularly notable. Disclosed are compositions with the general structural formula:
The compound 2-(1,2-Benzisothiazol-3(2H)-ylidene 1,1-dioxide)acetamide (I) has previously been reported (Melchiorre, Carlo, et al., Ann. Chim. (Rome) (1971), 61(6), 399-414). The method of synthesis utilized, however, is not useful for the preparation of the N-substituted amides of the present invention since the formation of the amide reported by Melchiorre requires the hydrolysis of a nitrile. This hydrolysis procedure can only lead to unsubstituted amides, according to the following reaction sequence.
It would be highly desirable to obtain negative charge control agents useful in electrostatographic toners and developers which agents have favorable charging and other relevant characteristics.
SUMMARY OF THE INVENTION
The invention provides an electrophotographic toner having a polymeric binder and a charge control agent, a 2-(1,2-benzisothiazol-3(2H)-ylidene 1,1-dioxide)acetamide, having the following structure:
wherein n is 1 or 2; R and R
1
independently represent hydrogen; linear, branched or cyclic, substituted or unsubstituted C1 to C18 alkyl; substituted or unsubstituted C6 to C10 aryl; substituted or unsubstituted C7 to C11 aralklyl; substituted or unsubstituted C5 to C10 heterocyclic ring; or R and R
1
together with N form a ring structure; or R
1
is a divalent linking group; with the proviso that when n is 2, R
1
is a divalent group.
The charge-control agents are useful in electrostatographic toners and developers. It is an advantageous effect of the invention that negatively charging toners can be provided which have favorable charging characteristics.
DETAILED DESCRIPTION OF THE INVENTION
The term “particle size” as used herein, or the term “size,” or “sized” as employed herein in reference to the term“particles,” means the median volume weighted diameter as measured by conventional diameter measuring devices, such as a Coulter Multisizer, sold by Coulter, Inc. of Hialeah, Fla. Median volume weighted diameter is an equivalent weight spherical particle which represents the median for a sample; that is, half of the mass of the sample is composed of smaller particles, and half of the mass of the sample is composed of larger particles than the median volume weighted diameter.
The term “charge-control,” as used herein, refers to a propensity of a toner addendum to modify the triboelectric charging properties of the resulting toner.
The term “glass transition temperature” or “T
g
”, as used herein, means the temperature at which a polymer changes from a glassy state to a rubbery state. This temperature (T
g
) can be measured by differential thermal analysis as disclosed in “Techniques and Methods of Polymer Evaluation,” Vol. 1, Marcel Dekker, Inc., New York, 1966.
The invention provides an electrophotographic toner having a polymeric binder and 2-(1,2-benzisothiazol-3(2H)-ylidene 1,1-dioxide)acetamides as charge control agents which have the following structure:
wherein n is 1 or 2 and R and R
1
independently represent hydrogen, linear, branched or cyclic, substituted or unsubstituted C1 to C18 alkyl, such as 2-chloroethyl, methyl, t-butyl, octadecyl, and cyclohexyl; substituted or unsubstituted C6 to C10 aryl such as, phenyl, 1-naphthyl, 4-chlorophenyl, 3-nitrophenyl, 3-hydroxyphenyl, 4-nitrophenyl, 3-methoxyphenyl, 4-methyiphenyl, 3,4,5-trichlorophenyl, 2,3,5,6-tetrafluorophenyl, 2,3,4,5,6-pentafluorophenyl and 4-nitro-1-naphthyl; substituted or unsubstituted C7 to C11 aralkyl such as benzyl; C5 to C10 heterocyclic ring system such as 2-benzothiazolyl, 2-fuiryl, and 2-thiazolyl; or R and R
1
, together with N form a ring structure such as ethyleneimine, azetidine, pyrrolidine, piperidine or hexamethyleneimine; or R
1
is a divalent linking group such alkylene, alkylidene, arylene, oxydiarylene, arylenedialkylene, alkylenediarylene or alkylidenediarylene. Examples of these linking groups include 1,4-phenylene, 4,4′-methylenediphenylene, 4,4′-oxydiphenylene, 1,6-hexamethylene, 4,4′-isopropylidene and &agr;,&agr;′-p-xylylene. Compounds containing two 2-(1,2-benzisothiazol-3(2H)-ylidene 1,1-dioxide)acetamide moieties would be the result of this type
Fields Robert D.
McGrath Gretchen S.
Srinivasan Satyanarayan A.
Wilson John C.
Eastman Kodak Company
Konkol Chris P.
Stockton Laura L.
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