Cabot Corp Issued Patent for Carbon Black Toners

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Cabot Corp Issued Patent for Carbon Black Toners

Cabot Corporation :Patent Issued for Carbon Blacks, Toners, and Composites and Methods of Making Same

By a News Reporter-Staff News Editor at Journal of Engineering — A patent by the inventors Shim, Anne K. (Plaistow, NH); Step, Eugene N. (Newton, MA); Kyrlidis, Agathagelos (Malden, MA), filed on June 6, 2008, was cleared and issued on March 12, 2013, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8394563 is assigned to Cabot Corporation (Boston, MA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to toner compositions comprising modified pigments. The present invention further relates to processes for preparing toners and the toners resulting from these processes. Also, the present invention relates to composites containing at least one filler or reinforcing agent, such as in particulate form. The present invention further relates to methods of preparing various composites, such as polymer matrixes containing at least one filler or reinforcing agent. Also, the present invention relates to methods of selecting one or more fillers or reinforcing agents based on compatibility with the matrix.

"Electrophotographic processes and image-forming apparatus are currently widespread. In electrophotography, an image comprising an electrostatic field pattern (also referred to as an electrostatic latent image), usually of nonuniform strength, is formed on an insulative surface of an electrophotographic element. The insulative surface typically comprises a photoconductive layer and an electrically conductive substrate. The electrostatic latent image is then developed or visualized into an image by contacting the latent image with a toner composition. Generally, the toner composition contains a resin and a colorant, such as a pigment. The toner image is then transferred onto a transfer medium such as paper and fixed thereon by heating and/or pressure. The last step involves cleaning residual toner from the electrophotographic element.

"In general, conventional dry toner compositions are prepared by combining a polymeric resin and a colorant followed by mechanical grinding (particle size attrition). The grinding process typically results in uncontrolled breakage of the particles, yielding toner compositions having irregular shapes with relatively wide particle size distributions.

"There is a growing need in the industry for toner compositions that can produce images having improved print quality using lower amounts of dry toner per page. In order to meet these needs, efforts have been made to improve the dispersibility of the colorant in the resin and reducing the overall particle size of the toner composition. However, the current mechanical grinding processes are not able to efficiently produce small particle size toners since the energy consumed in grinding typically increases exponentially with the particle size. Also, the irregularly shaped conventional toner particles cannot pack as well as regularly shaped particles, resulting in higher waste of toner per page.

"For this reason, various processes have been developed which produce toner particles having small and/or regular shapes. These processes involve the formation of resin particles in the presence of the colorant. Toners produced using such ‘in situ’ processes are often referred to as ‘chemically prepared toners’ or CPTs. For example, a process has been developed in which a polymer latex is combined with an aqueous pigment dispersion and agglomerated using a coagulant to form polymer particles. Another process involves the aqueous suspension polymerization of a dispersion of pigment in at least one monomer. Also, a pigment/polyester resin dispersion has been prepared and combined with water, followed by evaporation of the solvent. Each of these processes results in small particle size toner compositions having regular shapes. However, for each of these processes, since smaller particles result, the dispersibility of the colorant in the polymer becomes very important in order to maintain or improve the properties of the toner. To provide good dispersibility, high levels of dispersants must be included in the chemical toner processes. This has a negative impact on the overall performance of the toner composition, particularly the viscosity of the mixtures used to prepare the toners as well as the moisture sensitivity of the resulting chemical toner. Other issues have also been found.

"Modified pigments having attached organic groups have been disclosed for use in toner compositions. For example, U.S. Pat. No. 6,218,067 discloses, in part, a toner composition comprising the product of a mixture of resin particles and chargeable modified pigment particles. The modified pigment particles comprise at least one organic ionic group attached to the pigment particles and at least one amphiphilic counterion. Also, U.S. Pat. Nos. 5,955,232 and 6,054,238 disclose, in part, toner compositions comprising resin particles and modified pigment particles having attached at least one positively chargeable organic group. In addition, U.S. Patent Publication No. 2002-0011185 discloses, in part, a modified pigment product comprising a pigment having attached at least one organic group represented by the formula –X-Sp-Alk, wherein X, which is directly attached to the pigment, represents an arylene, heteroarylene, or alkylene group, Sp represents a spacer group, and Alk represents an alkenyl or alkyl group containing 50-200 carbon atoms. Toner compositions are also disclosed. Furthermore, U.S. Pat. Nos. 6,337,358 and 6,372,820 and U.S. Patent Publication No. 2002-0055554 disclose, in part, toner compositions comprising modified particles having attached polymeric groups. While these previous inventions describe the use of toners containing pigments having particular types of attached organic groups, none of these patents/publications take into consideration the need to have excellent compatibility of the pigment with attached organic group with the polymer components of the toner. For instance, one cannot simply use any attached organic group on a pigment and achieve an acceptable toner composition. An attached organic group may not be compatible with the polymer components of the toner composition. Phase separation of the organic group may occur where the organic group separates or the organic groups on the pigment cause an agglomeration of the pigments when added to the polymer components thereby preventing the formation of chemical toner particles. Accordingly, particular types of organic groups paired with the remaining parts of the toner composition need to be developed which will avoid these additional problems and disadvantages. There also remains a need for toners, in particular chemical toners, with properties capable of meeting the increasingly demanding print performance, efficiency, and cost requirements of the industry."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors’ summary information for this patent: "A feature of the present invention is to provide a chemical toner composition.

"Another feature of the present invention is to provide a toner composition that provides a uniform dispersion of the pigment throughout the toner composition and preferably has no agglomerates or few agglomerates of the pigment present in the toner composition.

"An additional feature of the present invention is to provide a means to disperse one or more pigments in one or more polymers to form a chemical toner composition.

"A further feature of the present invention is to provide a means to select proper fillers so that they are compatible with emulsion polymers or suspension polymers in the formation of a chemical toner.

"Another feature is to provide a polymer composite that is a chemical toner for electrophotography having improved fixing properties, such as lower toner fixing temperature.

"Additional features and advantages of the present invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.

"To achieve these and other advantages, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates to toner compositions, particularly chemically prepared toner compositions, comprising a resin and a colorant. In one embodiment, the colorant is a modified colorant (e.g., modified pigment) comprising a colorant having attached at least one organic group having one of the formulas: –Ar, –Ar-Alk.sub.x,

"##STR00001## Where Ar is an aryl or arylene group, Alk is an alkyl or alkylene group, such as an unsubstituted or substituted alkyl or alkylene group, x is an integer of 1 to 5, n is an integer of 1 to 5, 1 is an integer of 1 to 5, k is an integer of 1 to 10, m is 10-k, and where x is 2 or more, each of the substituents can be the same or different. The modified colorant can be a colorant with at least one adsorbed polymer on the colorant’s surface, such as a polymer that is a phenyl containing polymer, such as a polystyrene, a poly(styrene-acrylate), a polyester, or a poly(phenylmethylsiloxane). The toner composition can have a substantially smooth surface and/or a particle size from about 3 to about 10 microns.

"The present invention further relates a process for preparing a toner composition, particularly a chemical toner composition, comprising the steps of: i) combining an aqueous dispersion comprising a colorant, an aqueous emulsion comprising at least one polymer, and an optional wax to form a mixture, ii) forming a coagulated toner from the mixture; and iii) heating the coagulated toner above the Tg of the polymer to form a toner. The colorant can be the modified colorant as described above and herein. The process may further comprise the step of encapsulating the toner. The present invention further relates to the toner composition produced by this process.

"The present invention further relates a process for preparing a toner composition, particularly a chemical toner composition, comprising the steps of: i) forming a dispersion of a colorant in at least one monomer; ii) forming a suspension of the dispersion in an aqueous medium; and iii) polymerizing the suspension to form a toner. The colorant can be the modified colorant described above and herein. The process may further comprise the step of encapsulating the toner. The present invention further relates to the toner composition produced by this process.

"The present invention further relates a process for preparing a toner composition, particularly a chemical toner composition, comprising the steps of: i) forming a dispersion of a colorant in a polymer solution comprising at least one non-aqueous solvent and at least one polyester; ii) forming an emulsion of the dispersion in an aqueous medium; and iii) evaporating the solvent to form a toner. The colorant can be the modified colorant as described above and herein. The process may further comprise the step of encapsulating the toner. The present invention further relates to the toner composition produced by this process.

"The present invention also relates to a polymer composite that is chemical toner for electrophotography having improved fixing properties. The chemical toner is prepared with treated colorant that is dispersed in at least one polymer, such as an emulsion or suspension polymer. In one embodiment, the surface-modified colorant can be treated carbon black. Chemical toner prepared with treated colorants such as a treated carbon black can have a lower fixing temperature than chemical toner prepared with conventional carbon black, such as carbon black without attached chemical groups.

"It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present invention, as claimed.

"The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate some of the embodiments of the present invention and together with the description, serve to explain the principles of the present invention."

URL and more information on this patent, see: Shim, Anne K.; Step, Eugene N.; Kyrlidis, Agathagelos. Carbon Blacks, Toners, and Composites and Methods of Making Same. U.S. Patent Number 8394563, filed June 6, 2008, and issued March 12, 2013. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=64&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=3181&f=G&l=50&co1=AND&d=PTXT&s1=20130312.PD.&OS=ISD/20130312&RS=ISD/20130312

Keywords for this news article include: Legal Issues, Cabot Corporation.

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March 26, 2013 at 8:29 AM