This invention is generally directed to toner and developer compositions, and more specifically the present invention is directed to toner compositions, including magnetic, single component, and colored toner compositions containing as additives waxes and charge enhancing additives. In one embodiment of the present invention, the toner compositions are comprised of resin particles, pigment particles, charge enhancing additives, low molecular weight waxes such as polypropylene and polyethylene, and waxes with hydroxyl functionality to which has been added charge control additives thereby enabling control of the electrical, such as the triboelectric charge of the wax. There is also provided in accordance with the present invention positively, or negatively charged toner compositions comprised of resin particles, pigment particles, charge enhancing additives, and preferably externally blended waxes illustrated therein especially waxes with hydroxyl functionality to which have been added charge enhancing additives. In addition, the present invention is directed to developer compositions comprised of the aforementioned toners, and carrier particles. Furthermore, in another embodiment of the present invention there are provided single component toner compositions comprised of resin particles, magnetic components, such as magnetites, charge enhancing additives, and preferably externally blended waxes with hydroxyl functionality to which have been added or incorporated charge enhancing additives. The toner and developer compositions of the present invention are useful in electrophotographic printing and imaging systems, especially those processes wherein blade cleaning of the photoconductive member is accomplished. Moreover, the toner and developer compositions of the present invention enable images with substantially no micro-spots, or comets thereon; and these compositions possess stable and/or substantially uniform elecrical properties for extended time periods. Thus, with the toner and developer compositions of the present invention there is enabled substantial uniformity of the toner triboelectric charge; and the triboelectric charge of the wax selected is maintained at substantially the same tribolectric charge of the toner, or at a charge level and magnitude that will provide optimal performance in an imaging or printing system, including for example if it is intended that the wax be incorporated in the developed image, then the wax has the samme charge as the toner. However, when the wax is to be developed in the background image areas it should have a charge thereon which is near zero, or opposite in magnitude to that of the toner. The preferred location for the deposition of the wax depends on its intended use, for example, when present in the image it can act as a fusing and cleaning assist, and when present in the image background it can function as a cleaning assist, or a fusing assist if a pretransfer charging device is selected. Additionally, there is provided in accordance with the present invention toner compositions wherein waxes inclusive of the polymeric alcohols with charge additives are present therein as internal or preferably external additives. In addition, the present invention is directed to developer compositions comprised of the aforementioned toners, and carrier particles.
Moreover, the toner and developer compositions of the present invention enable the photoconductive imaging member present in an imaging apparatus to function for extended time periods, for example, up to 100,000 imaging cycles while simultaneously preventing the localized accumulation of undesirable toner debris thereon, which can encompass sufficient areas of the photoconductive members and/or to permit unwanted toner spots to be present on the final developed output copy. Further, the developer compositions of the present invention possess stable electrical properties for extended time periods, and with these compositions, for example, there is no substantial change in the selected triboelectrical charging values, and substantially no degradation in A.sub.t which is the product of the toner concentration+1 multiplied by the triboelectric charging value.
Developer and toner compositions with certain waxes therein are known. For example, there are illustrated in U.K. Patent Publication No. 1,442,835, the disclosure of which is totally incorporated herein by reference, toner compositions containing resin particles, and polyalkylene compounds, such as polyethylene and polypropylene of a molecular weight of from about 1,500 to 6,000, reference page 3, line 97 to 119, which compositions prevent toner offsetting in electrostatic imaging processes. Additionally, the '835 publication discloses the addition of paraffin waxes together with, or without a metal salt of a fatty acid, reference page 2, lines 55 to 58. In addition, many patents disclose the use of metal salts of fatty acids for toner compositions, such as U.S. Pat. No. 3,655,374. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplsihed, reference Palmeriti et al. U.S. Pat. No. 3,635,704, issued Jan. 18, 1972, the disclosure of which is totally incorporated herein by reference. Additionally, there are illustrated in U.S. Pat. No. 3,983,045 three component developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43. There is no teaching, however, in any of these patents with respect to the toner compositions with modified waxes or treated waxes, that is waxes with charge additives, especially the specific modified polymeric hydroxy waxes selected for the invention of the present application in one embodiment. With the present invention as contrasted to the prior art, for example, the charging characteristic of the waxes selected can be preselected, that is the specific charge thereon, and the magnitude thereof can be controlled, for example, the charge on the wax can be equal to greater, or less than the toner charge depending on its intended end use in the xerographic process. Typically, such waxes are added to enhance the performance of cleaning subsystems in xerographic devices by assuring that the photoreceptor is free of toner debris. Moreover, the toner and developer compositions of the '045 patent do not possess many of the advantages as illustrated herein with respect to the toner and developer compositions with the polymeric alcohol waxes therein, that is for example the developer compositions of the '045 patent do not possess stable electrical properties in several imaging apparatuses, and with these compositions there is degradation in A.sub.t with extended imaging impressions, that is exceeding, for example, 100,000 developed images; nor, for example, does the incorporation of metal salts or metal salts of fatty acids such as zinc stearate or the addition of colloidal silicas, or mixtures thereof enable the elimination of toner spots on the final image copy with toner compositions, a disadvantage alleviated with the toner and developer compositions of the present application. Moreover, alkylenes and the polymeric alcohol waxes with charge enhancing additives selected for the compositions of the present invention possess the other advantages illustrated herein.
Described in U.S. Pat. No. 4,367,275 are methods of preventing offsetting of electrostatic images of the toner composition to the fuser roll, which toner subsequently offsets to supporting substrates such as papers wherein there are selected toner compositions containing specific external lubricants including various waxes, see column 5, lines 32 to 45, which waxes are substantially different in their properties and characteristics than the polymeric alcohol waxes selected for the toner and developer compositions of the present invention; and moreover, the toner compositions of the present invention with the waxes illustrated herein especially the polymeric alcohol additives possess advantages, such as elimination of toner spotting not achievable with the toner and developer compositions of the '275 patent and controlled preselected charges for the wax particles selected.
Other references of interest include U.S. Pat. Nos. 4,072,521, which discloses the use of amides as toner additives; 4,073,649 and 4,076,641. Furthermore, references of background interest are U.S. Pat. Nos. 3.165,420; 3,236,776; 4,145,300; 4,271,249; 4,556,624; 4,557,991; and 4,604,338.
Moreover, toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided collodidal silica. According to the disclosure of this patent, the development of images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there is illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions; and in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride. Other prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; and 4.394,430. Toner compositions with negative charge enhancing additives are also known.
In U.S. Pat. No. 4,556,624 there are illustrated toner compositions wherein the toner polymer, pigment, certain waxes and a charge control agent are melt blended in bulk and then micronized, see for example column 7.
Illustrated in copending application U.S. Ser. No. 004,939/87, now U.S. Pat. No. 4,883,736, the disclosure of which is totally incorporated herein by reference are toner and developer compositions with linear polymeric alcohols comprised of a fully saturated hydrocarbon backbone with at least about 80 percent of the polymeric chains terminated at one chain end with a hydroxyl group, which alcohol is represented by the following formula: EQU CH.sub.3 (CH.sub.2).sub.n CH.sub.2 OH
wherein n is a number of from about 30 to about 300; and preferably of from about 30 to about 100, which alcohols are available from Petrolite Corporation. Particularly preferred polymeric alcohols include those wherein n represents a number of from about 30 to about 50. Therefore, the polymeric alcohols selected have a number average molecular weight as determined by gas chromatography of from about greater than 450 to about 1,400, and preferably of from about 475 to about 750. In addition, the aforementioned polymeric alcohols are present in the toner and developer compositions in various effective amounts as finely divided uniformly dispersed external additives. More specifically, the polymeric alcohols are present in an amount of from about 0.05 percent to about 20 percent by weight. Therefore, for example, as external additives the polymeric alcohols are present in an amount of from about 0.5 percent by weight to slightly less than about 5 percent by weight. The aforementioned alcohols are also selected for the invention of the present application, which alcohols, however, have added thereto charge enhancing additives as indicated herein.
The aforementioned, copending application also discloses the addition of charge control additives to the toner composition. With the invention of the present application, in one embodiment the waxes selected are first treated with charge enhancing additives and subsequently the toner and developer compositions are prepared thereby permitting, for example, the advantages illustrated herein including the preselection of charge on the wax, and selection of the charge present on the toner, which charge remains stable for extended time periods exceeding, for example, 250,000 imaging cycles. Generally, the aforesaid charge is from about a positive or negative 15 to about 35 microcoulombs per gram.
Although the above described toner and developer compositions are useful for their intended purposes, there is a need for improved compositions. More specifically, there is a need for toner compositions, including single component compositions which possess advantages not achievable with the prior art compositions. There is also a need for toner compositions with certain waxes that are particularly useful in electrostatic imaging processes wherein blade cleaning is utilized for the prevention of the deposition of unwanted toner particles on the photoreceptor surface; and wherein there results no undesirable toner spots on the images resulting. In addition, there is a need for toner and developer compositions that maintain their triboelectrical characteristics for extended time periods exceeding, for example, 100,000 developed images, and wherein the wax mixture possesses a triboelectric charge substantially equivalent to the toner compositions. Further, there is a need for toners that deposit in background regions of the formed image on the photoreceptor, thus a lower charge on the wax than on the toner is selected. In addition, there is a need for toner and developer compositions that simultaneously prevent toner spots, maintain stable electrical characteristics for intended time periods, and maintain the toner triboelectric charge at a uniform value. Furthermore, there is a need for single component toners and colored toners that possess many of the aforementioned characteristics. Also, there is a need for toner and developer compositions with certain toxicologically safe and economical waxes with charge enhancing additives incorporated therein, or on the surface thereof that allow the aforementioned advantages, and other advantages to be obtained.
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