Toner and methods for producing toner particles

Abstract

Toner comprising a core and a shell, wherein the core comprises a resin comprising a first non-crosslinked polymer in combination with a crosslinked polymer, and at least one modified paraffin wax having branched carbon chains in combination with linear carbon chains, wherein the shell comprises a second non-crosslinked polymer present in an amount of 20% to 40% by weight of the toner, and wherein the branched carbon chains of the at least one modified paraffin wax are present in an amount of 1% to 20% of the at least one modified paraffin wax and have a molecular weight number average of 520 to 600, and wherein the linear carbon chains are present in an amount of 80% to 99% of the at least one modified paraffin wax and have a molecular weight number average of 505 to 530.

Description

The present disclosure relates to toners and methods for producing toner particles. The toners are suitable for electrostatographic devices, including xerographic devices such as digital image-on-image devices. Numerous processes for the production of toners fall within the scope of application of a person skilled in the art. One of these processes is emulsion aggregation (EA). These toners fall within the scope of application of such professionals and can be produced by aggregating a colorant with a latex polymer formed by emulsion polymerization. Some high-gloss EA toners utilize resins with a core-shell configuration, featuring a resin with a lower glass transition temperature (Tg) in the core and a resin with a higher Tg in the shell. Such toners may contain waxes and can be manufactured with aluminum-based aggregating agents. Manufacturing processes for these toners may employ complexing agents to remove aluminum ions as well as to prevent crosslinking of lower ions, thereby increasing gloss. One drawback of these toners is their tendency to cause blockage problems and their potential for a significant amount of protruding wax on the surface. Improved manufacturing processes that reduce manufacturing time and allow for excellent control of toner particle charge remain desirable. EP 1 775 640 A1 describes a toner with EA toner particles comprising a core and a shell. The core comprises a binder, a colorant, a wax, and a modified silicon dioxide. The binder comprises a first non-crosslinked styrene acrylate polymer and a crosslinked styrene acrylate polymer. Examples of suitable waxes are linear polyethylene waxes, paraffin waxes, polypropylene waxes, carnauba wax, and microcrystalline waxes. The shell comprises a second non-crosslinked styrene acrylate polymer. The present disclosure provides toner formulations suitable in embodiments for monochrome printers with single-component development (SCD). Toners of the present disclosure can exhibit improvements in hot offset and fusing ratio performance, as well as higher optical density of the printed images. Methods for producing such toners are also provided. More precisely, the present disclosure relates to a toner comprising a core and a shell, wherein the core comprises a resin comprising a first non-crosslinked polymer in combination with a crosslinked polymer, and at least one modified paraffin wax having branched carbon chains in combination with linear carbon chains, wherein the shell comprises a second non-crosslinked polymer present in an amount of 20% to 40% by weight of the toner, and wherein the branched carbon chains of the at least one modified paraffin wax are present in an amount of 1% to 20% of the paraffin wax and have a molecular weight number average of 520 to 600, and wherein the linear carbon chains are present in an amount of 80% to 99% of the at least one modified paraffin wax and have a molecular weight number average of 505 to 530. The present disclosure further relates to a process for producing toner particles constituting a toner, comprising: contacting an emulsion comprising a first non-crosslinked polymer in combination with a crosslinked polymer with at least one modified paraffin wax having branched carbon chains in combination with linear carbon chains; wherein the branched carbon chains of the at least one modified paraffin wax are present in an amount of 1% to 20% of the paraffin wax;and have a molecular weight number average of 520 to 600, and wherein the linear carbon chains are present in an amount of 80% to 99% of the at least one modified paraffin wax and have a molecular weight number average of 505 to 530; aggregating particles by contacting the particles with an aggregating agent in an amount of 0.1 parts per hundred to 0.25 parts per hundred to form aggregated particles; forming a shell over the aggregated particles by contacting the aggregated particles with an emulsion comprising a second non-crosslinked polymer; wherein the second non-crosslinked polymer is present in an amount of 20% by weight of the toner to 40% by weight of the toner; and recovering the toner particles, wherein the toner particles have a roundness of 0.900 to 0.999. Preferred embodiments of the present disclosure are specified in the dependent claims. Figures 1A-1D are scanning electron microscope (SEM) images of the particles made from a latex polymer according to the present disclosure; and Figures 2A-2D are scanning electron microscope (SEM) images of the toners made according to the present disclosure. The present disclosure provides toners and methods for producing toner particles. In embodiments, the toners of the present disclosure can be produced by combining a latex polymer, a wax, optionally a colorant, and other optional additives. While the latex polymer can be produced by any method within the scope of application for those skilled in the field, in embodiments the latex polymer can be produced by emulsion polymerization processes, including semi-continuous emulsion polymerization, and the toner can comprise emulsion aggregation toners. Emulsion aggregation comprises the aggregation of submicrometer-sized latex with colorant particles to toner-sized particles, wherein the growth in particle size ranges, for example, from 0.1 micrometers to 15 micrometers in embodiments. resin Any suitable monomer can be used to produce a latex for use in toner. As mentioned above, the toner can be produced in various embodiments by means of emulsion aggregation. Suitable monomers that are useful for the formation of a latex polymer emulsion, and therefore also include the resulting latex particles in the latex emulsion, are not limited to styrenes, acrylates, methacrylates, butadienes, isoprenes, acrylic acids, methacrylic acids, acrylonitriles, and combinations thereof and the like. In some embodiments, the latex polymer can comprise at least one polymer. In some embodiments, one of these polymers can be from about one to about twenty, and in others, from about three to about ten. Examples of polymers include styrene acrylate, styrene butadiene, styrene methacrylate, and more specifically, poly(styrene-alkyl acrylate), poly(styrene-1,3-diene), poly(styrene-alkyl methacrylate), poly(styrene-alkyl acrylate-acrylic acid), poly(styrene-1,3-diene-acrylic acid), poly(styrene-alkyl methacrylate-acrylic acid), poly(alkyl methacrylate-alkyl acrylate), poly(alkyl methacrylate-aryl acrylate), poly(aryl methacrylate-alkyl acrylate), poly(alkyl methacrylate-acrylic acid), poly(styrene-alkyl acrylate-acrylonitrile-acrylic acid), poly(styrene-1,3-diene-acrylonitrile-acrylic acid), poly(alkyl acrylate-acrylonitrile-acrylic acid), poly(styrene-butadiene), poly(methyl styrene-butadiene), poly(methyl methacrylate-butadiene), and poly(ethyl methacrylate-butadiene). Poly(propyl methacrylate butadiene), Poly(butyl methacrylate butadiene), Poly(methyl methacrylate butadiene),Poly(ethyl acrylate-butadiene), Poly(propyl acrylate-butadiene), Poly(butyl acrylate-butadiene), Poly(styrene-isoprene), Poly(methyl styrene-isoprene), Poly(methyl methacrylate-isoprene), Poly(ethyl methacrylate-isoprene), Poly(propyl methacrylate-isoprene), Poly(butyl methacrylate-isoprene), Poly(methyl acrylate-isoprene), Poly(ethyl acrylate-isoprene), Poly(propyl acrylate-isoprene), Poly(butyl acrylate-isoprene), Poly(styrene-propyl acrylate), Poly(styrene-butyl acrylate), Poly(styrene-butadiene-acrylic acid), Poly(styrene-butadiene-methacrylic acid), Poly(styrene-butadiene-acrylonitrile-acrylic acid), Poly(styrene-butyl acrylate-acrylic acid), Poly(styrene-butyl acrylate-methacrylic acid), Poly(styrene-butyl acrylate-acrylonitrile) Poly(styrene-butylacrylate-acrylonitrile-acrylic acid), Poly(styrene-butadiene), Poly(styrene-isoprene), Poly(styrene-butylmethacrylate), Poly(styrene-butylacrylate-acrylic acid), Poly(styrene-butylmethacrylate-acrylic acid), Poly(butylmethacrylate-butylacrylate), Poly(butylmethacrylate-acrylic acid), Poly(acrylonitrile-butylacrylate-acrylic acid)as well as combinations thereof. The polymers can be block, random, or alternating copolymers. Polyester resins that can be used include those obtained from the reaction products of bisphenol A and propylene oxide or propylene carbonate, as well as polyesters obtained by reacting these reaction products with fumaric acid, and branched polyester resins resulting from the reaction of dimethyl terephthalate with 1,3-butanediol, 1,2-propanediol and pentaerythritol. In embodiments, a poly(styrene-butyl acrylate) can be used as the latex polymer. The glass transition temperature of this latex, which in embodiments can be used to form a toner of the present disclosure, can be from 35 °C to 75 °C, and in embodiments from 40 °C to 70 °C. surfactants In some embodiments, the latex can be produced in an aqueous phase containing a surfactant or cosurfactant. Surfactants that can be used with the polymer to form a latex dispersion can be ionic or non-ionic surfactants in an amount sufficient to produce a dispersion with 0.01 to 15% solids by weight, or in some embodiments, 0.1 to 10% solids by weight. The choice of specific surfactants or combinations thereof, as well as the quantities of each to be used, are within the scope of application of a person skilled in the art. initiators In some embodiments, initiators can be added to form the latex polymer. Initiators can be added in suitable quantities, such as 0.1 to 8 percent by weight of the monomers, and in embodiments from 0.2 to 5 percent by weight of the monomers. Chain transmission equipment In embodiments, chain transfer agents can also be used in the formation of the latex polymer. Suitable chain transfer agents include dodecanethiol, octanthiol, carbon tetrabromide, and combinations thereof, in amounts of 0.1 to 10 percent and, in embodiments, of 0.2 to 5 percent by weight of the monomers, to control the molecular weight properties of the latex polymer when the emulsion polymerization is carried out according to the present disclosure. Gel latex In embodiments, a gel latex can be added to the non-crosslinked latex resin suspended in the surfactant. As used here, a gel latex can, in embodiments, refer to a crosslinked resin or polymer, or to a non-crosslinked resin as described above that has undergone crosslinking. The gel latex can comprise submicrometer-sized, cross-linked resin particles with a mean volume diameter of 10 to 200 nanometers, or, in embodiments, 20 to 100 nanometers. The gel latex can be suspended in an aqueous phase containing surfactant, with the surfactant present in an amount of 0.5 to 5 percent by weight of the total solids, or 0.7 to 2 percent by weight of the total solids. The crosslinked resin can be a crosslinked polymer such as crosslinked styrene acrylates, styrene butadienes, and / or styrene methacrylates. In particular, examples of crosslinked resins include crosslinked poly(styrene-alkyl acrylate), poly(styrene-butadiene), poly(styrene-isoprene), poly(styrene-alkyl methacrylate), poly(styrene-alkyl acrylate-acrylic acid), poly(styrene-butadiene-acrylic acid), poly(styrene-isoprene-acrylic acid), poly(styrene-alkyl methacrylate-acrylic acid), poly(alkyl methacrylate-alkyl acrylate), poly(alkyl methacrylate-acrylic acrylate), poly(aryl methacrylate-alkyl acrylate), poly(alkyl methacrylate-acrylic acid), poly(styrene-alkyl acrylate-acrylonitrile-acrylic acid), crosslinked poly(alkyl acrylate-acrylonitrile-acrylic acid), and mixtures thereof. The crosslinked resin may contain a crosslinker, such as... B. Divinylbenzene or other aromatic divinyl or divinyl acrylate or methacrylate monomers.The crosslinker can be present in an amount of approximately 0.01 to approximately 25 percent by weight of the crosslinked resin, or of approximately 0.5 to approximately 15 percent by weight of the crosslinked resin. The cross-linked resin particles can be present in an amount of 1 to 20 percent by weight of the toner, in embodiments from 4 to 15 percent by weight of the toner, and in embodiments from 5 to 14 percent by weight of the toner. In embodiments, the resin used to form the toner can be a mixture of a gel resin and a non-crosslinked resin. Functional monomers In embodiments, it may be advantageous to include a functional monomer in the formation of a latex polymer and the polymer-building particles. Suitable functional monomers include monomers with a carboxylic acid functionality. Such functional monomers may have the following formula (I): where R1 is hydrogen or a methyl group, and R2 and R3 are independently selected from alkyl groups containing 1 to 12 carbon atoms or a phenyl group; n is from 0 to 20, and in embodiments from 1 to 10. Examples of such functional monomers include beta-carboxyethyl acrylate (β-CEA), poly(2-carboxyethyl) acrylate, 2-carboxyethyl methacrylate, and combinations thereof. Other functional monomers that may be used include, for example, acrylic acid and its derivatives. In embodiments, the functional monomer, which possesses a carboxylic acid functionality, may also contain a small amount of metal ions, such as sodium, potassium, and / or calcium, to achieve improved emulsion polymerization results. The metal ions may be present in amounts ranging from 0.001 to 10% by weight of the functional monomer, or in embodiments, from 0.5% to 5% by weight. If available, the functional monomer can be added in an amount of 0.01 to 5 percent by weight of the toner, or in embodiments, in an amount of 0.05 to 2 percent by weight of the toner. Reaction conditions In the emulsion polymerization process, the reactants can be placed in a suitable reactor, such as a mixing vessel. The appropriate amount of at least two monomers (in some embodiments, two to ten monomers), surfactant(s), optionally a functional monomer, optionally an initiator, optionally a chain transfer agent, and optionally a colorant can be combined in the reactor, and the emulsion polymerization process can be initiated. Reaction conditions selected to effect emulsion polymerization include temperatures of, for example, 45 °C to 120 °C, or in some embodiments, 60 °C to 90 °C. Polymerization may take place until particles in nanometer size, from 50 nm to 800 nm in mean volume diameter, or in embodiments from 100 nm to 400 nm in mean volume diameter, can be formed, the size being determined, for example, by a Brookhaven nanoparticle size analyzer. pH adjuster In some embodiments, a pH adjuster may be added to control the rate of the emulsion aggregation process. The pH adjuster used in the processes of the present disclosure may be any acid or base that does not adversely affect the products prepared. Suitable bases may include metal hydroxides such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, and optionally combinations thereof. Suitable acids include nitric acid, sulfuric acid, hydrochloric acid, citric acid, acetic acid, and optionally combinations thereof. wax During the formation of a toner particle in an emulsion aggregation process, a modified paraffin wax is added. Paraffin waxes exhibiting modified crystal structures are referred to here as modified paraffin waxes. The modified paraffin waxes contain branched carbon chains in an amount of 1% to 20% of the paraffin wax, or in some embodiments, 8% to 16%, and linear carbon chains in an amount of 80% to 99% of the paraffin wax, or in some embodiments, 84% to 92%. The isomers present in such modified paraffin waxes, i.e., the branched carbon chains, have a molecular weight number-average (Mn) of 520 to 600, in embodiments of 550 to 570, and in embodiments of approximately 560. The linear carbon chains present in such waxes, occasionally referred to here as normal carbon chains, have an Mn of 505 to 530, in embodiments of 512 to 525, and in embodiments of approximately 518. The mass-average molecular weight (Mw) of the branched carbon chains in the modified paraffin waxes can be from 530 to 580, and in embodiments of 555 to 575, and the Mw of the linear carbon chains in the modified paraffin waxes can be from 480 to 550, and in embodiments of 515 to 535. For branched carbon chains, the mass-averaged molecular weight (Mw) of the modified paraffin waxes can represent a number of carbon atoms from 31 to 59 carbon atoms, in embodiments from 34 to 50 carbon atoms, with a maximum at about 41 carbon atoms, and for linear carbon chains, the Mw can represent a number of carbon atoms from 24 to 54 carbon atoms, in embodiments from 30 to 50 carbon atoms, with a maximum at about 36 carbon atoms. The modified paraffin wax can be present in an amount of 2 wt.% to 20 wt.% of the toner, in embodiments from 4 wt.% to 15 wt.% of the toner, in embodiments from 5 wt.% to 13 wt.% of the toner. One advantage of the present disclosure includes the smoothness obtained with particles formed from these waxes, as well as the fact that the wax does not migrate to the particle surface. colorant A colorant dispersion can be added to the latex particles and the wax. The colorant suspension can, for example, comprise submicrometer-sized colorant particles with a mean volume diameter of, for example, 50 to 500 nanometers, and in embodiments, 100 to 400 nanometers. The colorant particles can be suspended in an aqueous phase containing an anionic surfactant, a nonionic surfactant, or a combination thereof. In embodiments, the surfactant can be ionic and constitute 1 to 25 percent by weight of the pigment, and in embodiments, 4 to 15 percent by weight. The colorant may be present in the toner of the disclosure in an amount of 1 to 25 percent by weight of the toner, and in embodiments in an amount of 2 to 15 percent by weight of the toner. Examples of colorants in embodiments include Pigment Blue 15:3 (here occasionally referred to as PB 15:3 Cyan Pigment) with a Color Index Constitution Number 74160, Magenta Pigment Red 81:3 with a Color Index Constitution Number 45160:3, Yellow 17 with a Color Index Constitution Number 21105, and known dyes such as food colorings, yellow, blue, green, red, and magenta dyes. In other embodiments, a magenta pigment, Pigment Red 122 (2,9-dimethylquinacridone), Pigment Red 185, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 235, Pigment Red 269, and combinations thereof can be used as the colorant. Pigment Red 122 (here occasionally referred to as PR-122) was widely used for the pigmentation of toners, plastics, inks, and coatings due to its unique magenta hue. Peel Any latex listed above for the formation of the core latex can be used to form the shell latex. In some embodiments, a styrene-n-butyl acrylate copolymer can be used to form the shell latex. In some embodiments, the latex used to form the shell can have a glass transition temperature of 35 °C to 75 °C, and in others, 40 °C to 70 °C. A shell latex can be applied by any method within the scope of application of a person skilled in the art, including dipping or spraying. The shell latex can be applied until the desired final toner particle size is achieved, in embodiments from 3 micrometers to 12 micrometers, in other embodiments from 4 micrometers to 9 micrometers. In further embodiments, the toner particles can be produced by a semi-continuous, in-situ germinated emulsion copolymerization of the latex, with the shell latex being added once the aggregated particles have formed. The shell latex can be present in an amount of 20 to 40 percent by weight of the dry toner particles, in embodiments from 26 to 36 percent by weight of the dry toner particles, and in embodiments from 27 to 34 percent by weight of the dry toner particles. Aggregation funds In some embodiments, an aggregating agent can be added during or before the aggregation of the latex and the aqueous colorant dispersion. In embodiments, a suitable aggregating agent comprises polyaluminum chloride (PAC), which is commercially available and can be produced by the controlled hydrolysis of aluminum chloride with sodium hydroxide. Suitable amounts of the aggregating agent can range from 0.1 parts per hundred (pph) to 0.25 pph, and in embodiments from 0.12 pph to 0.20 pph. The resulting mixture of latex, optionally in a dispersion, optional colorant dispersion, wax and aggregating agent can then be stirred and heated to a temperature close to the Tg of the latex, in embodiments from 30 °C to 70 °C, in embodiments from 40 °C to 65 °C, which leads to toner aggregates of 3 micrometers to 15 micrometers in mean volume diameter, in embodiments from 5 micrometers to 9 micrometers in mean volume diameter. Once the desired final toner particle size is achieved, the pH of the mixture can be adjusted with a base to a value of 3.5 to 7, or in some embodiments, 4 to 6.5. The base can be any suitable base, such as alkali metal hydroxides like sodium hydroxide, potassium hydroxide, and ammonium hydroxide. The alkali metal hydroxide can be added in an amount of 0.1 to 30 percent by weight of the mixture, or in some embodiments, 0.5 to 15 percent by weight. The mixture of latex, optional colorant, and wax can then be coalesced. Coalescing can involve stirring and heating at a temperature of 80°C to 99°C, or in some embodiments, 85°C to 98°C, resulting in a toner shape, occasionally referred to here as roundness, of 0.900 to 0.999, or in some embodiments, 0.950 to 0.998, or 0.970 to 0.995. Coalescing can be accelerated by adjusting the pH of the mixture to less than 6 with, for example, an acid, in order to coalesce the toner aggregates. Once the desired shape of the toner particles has been achieved, the pH value of the mixture can be adjusted to a value of less than 9 using a base. The mixture can then be cooled down to less than the Tg of the particles in a cooling or freezing step. The toner slurry can then be washed to remove surfactants. The particles are then dried so that they have a moisture content of less than 1%. Particles according to the present disclosure can have a desirable surface area for use as toner. The surface area can be determined using the Brunauer, Emmett, and Teller method (BET method). The BET surface area of ​​a sphere can be calculated using the following equation: Toner particles can have a surface area of ​​0.5 m² / g to 1.4 m² / g, in embodiments of 0.6 m² / g to 1.2 m² / g, and in some embodiments of 0.7 m² / g to 1.0 m² / g. In embodiments, the toners of the present disclosure can have a triboelectric charge of -10 µC / g to -60 µC / g, and in embodiments of -20 µC / g to -50 µC / g. Toners of the present disclosure can also have an original toner charge / mass ratio (Q / M) of -3 µC / g to -35 µC / g and a charge of the final toner after mixing with surface additive of -10 µC / g to -45 µC / g. Additives Other optional additives that can be combined with a toner include any additive to improve the properties of toner compositions. The toner particles, produced using a latex, can have a size of 1 micrometer to 20 micrometers, in embodiments from 2 micrometers to 15 micrometers, and in embodiments from 6.5 micrometers to 8 micrometers. Toner particles of the present disclosure can have a roundness of 0.900 to 0.999, in embodiments from 0.950 to 0.998, and in some embodiments from 0.970 to 0.995. By following the methods of this disclosure, toner particles can be obtained which have several advantages compared to conventional toner: (1) Increased robustness of the triboelectric charge of the particles due, in part, to less wax on the surface of the particles, which reduces toner defects and improves machine performance, including flow behavior and low cohesion; (2) Simple implementation, requiring no significant changes to existing aggregation / coalescence processes; and (3) Increased productivity and reduced unit manufacturing cost (UMC) by reducing production time and necessary rework (improved yield quality due, at least in part, to the reproducible nature of the process). The toners of the present disclosure exhibit excellent properties, including hot offset, fixer ratio, and density. The fixer ratio of an image can be determined as follows. First, a status A density (OD1) is measured for each color of an image, and then adhesive tape is applied to the image. Subsequently, the adhesive tape is removed, and then a status A density (OD2) is measured for each color of the image. The optical density is measured using a spectrometer (for example, a Spectral Densitometer 938, manufactured by X-Rite). The optical densities thus determined are then used to calculate the fixer ratio according to the following equation. Toners of the present disclosure can have a fixer ratio of 0.5 to 1, and in embodiments, 0.6 to 0.9. By optimizing the particle size, in some cases from 6.5 micrometers to 7.7 micrometers, the toners of the present disclosure can be particularly suitable for bladeless cleaning systems, i.e., for single-component development (SCD) systems. With a suitable sphericity, the toners of the present disclosure can support optimal machine performance. The use of N-539 wax results in almost no wax being present on the surface; wax globules are formed beneath the particle's surface, leading to very smooth surfaces and very round particles. This enables good flow properties and low cartridge torques. Applications Toners according to the present disclosure can be used in a variety of imaging devices, including printers and copiers. The toners produced according to the present disclosure are ideally suited for imaging processes, especially xerography, and can provide high-quality color images with excellent image resolution, good signal-to-noise ratio, and image homogeneity. Furthermore, the toners of the present disclosure can be selected for electrophotographic imaging and printing processes, such as digital imaging systems and methods. Developer compositions can be prepared by mixing toners obtained by the processes disclosed herein with known carrier particles, including coated carriers such as steel or ferrites. The carriers can be present in an amount of 2% to 8% by weight of the toner, or 4% to 6% by weight of the toner. The carrier particles can also comprise a core with an overlying polymer coating, such as polymethyl methacrylate (PMMA), containing a conductive component dispersed therein, such as conductive carbon black. Development can occur via discharge area development. In discharge area development, the photoreceptor is charged, and then the areas to be developed are discharged. The development fields and toner charges are designed such that the toner is repelled by the charged areas on the photoreceptor and attracted by the discharged areas. Development can be achieved by the magnetic brush development process described in US 2,874,063 A. This process involves a magnet carrying the toner containing a developer material as described in the present disclosure, as well as magnetic carrier particles. The magnetic field of the magnet causes the magnetic carriers to align in a brush-like configuration, and this "magnetic brush" is brought into contact with the surface of the photoreceptor that bears the electrostatic image. The toner particles are attracted by the brush to the electrostatic image on the discharged areas of the photoreceptor by means of electrostatic attraction, resulting in image development. In embodiments, a conductive magnetic brush process is used in which the developer comprises conductive carrier particles and can conduct an electric current from the pre-magnetized magnet through the charge carriers to the photoreceptor. Imaging Imaging methods are also provided for with the toners disclosed herein. The imaging method comprises generating an image in an electronic printing and magnetic image character recognition device and subsequently developing the image with a toner composition of the present disclosure. The formation and development of images on the surface of photoconductive materials by electrostatic means is well known. The basic xerographic process involves applying a uniform charge to a photoconductive insulating layer, exposing the layer to a light and shadow image to distribute the charge over the area of ​​the light-exposed layer, and developing the resulting latent electrostatic image by depositing a finely dispersed electroscopic material, for example, toner, onto the image.The toner is normally attracted to those areas of the layer that have retained a charge, thus forming a toner image corresponding to the latent electrostatic image. This powder image can then be transferred to a substrate such as paper. The transferred image can subsequently be permanently fixed to the substrate using heat. Instead of forming the latent image by uniformly charging the photoconductive layer and then exposing the layer to a light and shadow pattern, the latent image can also be formed by directly charging the layer in an image configuration. The powder image can then be fixed to the photoconductive layer, thus eliminating the powder image transfer. Other suitable fixing agents, such as solvent or coating treatments, can replace the aforementioned heat fixing step. The following examples are provided to illustrate the embodiments of the present disclosure. Unless otherwise stated, all parts and percentages refer to weight. EXAMPLE 1 Toner was prepared using a 10-liter Henschel mixer. The amounts of gel and wax were optimized to avoid problems with hot offset and fixer ratio. The general formulation is summarized in Table 1 below. Water was added to achieve a solids content of approximately 14% in the reactor. The target properties of the toner are summarized in Table 2 below. Core latex (styrene / butyl acrylate) 11.8 Shell latex (styrene / butyl acrylate)8.79 Gel latex (cross-linked styrene / butyl acrylate) 3.52 Regal 330 (soot pigment) 2.77 Pigment Blue 15:3(cyan pigment)0.71 Paraffin wax dispersion 4.51 Polyaluminum chloride(PAC)0.187 0.02M HNO31,683 deionized H2O / reactor 25.7 deionized H2O for rinsing 4.0 Table 2 Objectives Table 2 Objectives Particle size, mean volume (both final slurry and dry particles) approximately 7.2 µm Roundness (final slurry and dry particles), Sysmex 3000>0.990 The optimized formulation was found to consist of approximately 8% gel, approximately 10-12% wax, 3-4% carbon black, and 1% cyanopigment, using a latex resin with a particle size of approximately 231 nm, with approximately 14% solids and approximately 32% in the tray. The optimal formulation is summarized in Table 3 below. Table 3: % dry toner particles Toner 100 Core resin 43.00 Shell resin 32.00 Gel latex 8.00 Shelf 3304.00 PB 15:31.00 Paraffin wax 12.00 This formulation proved to be helpful in making the toner particles more robust against hot offset (due to the wax inclusion) and blockages (due to the reduced gel content). SEM images of the particles of the latex polymer used are shown in Figures 1A-1D, and SEM images of the optimal toner formulation from Table 3 are shown in Figures 2A-2D. The images demonstrate the high roundness of the toner with a surface that is completely free of wax. The toner exhibited excellent hot-offset performance at approximately 205 °C and approximately 215 °C. The fixer ratio of this toner in the B-zone of an electrophotographic apparatus was compared with that of a commercially available toner. The fixer ratio of the toner of the present disclosure was improved, most frequently reaching 165 °C at 80%, compared to more than 180 °C for the commercially available toner. The reduced fixer ratio of the toner of the present disclosure resulted in better image quality and adhesion to the substrate. Particle experiments were conducted to investigate the gel and wax content for improving hot offset printing performance. It was found that the toner formulations designated 0127 (which is the formulation summarized in Table 3 above), along with formulations 0151 and 0165, exhibited the best performance at low gel and high wax content. Furthermore, these toners showed good storage stability at 50 °C. The melt flow index (MFI) of the particles ranged from 4 to 15 g / 10 minutes at approximately 130 °C / 10 kg weight, as determined using a Shimatzu CFT500D capillary rheometer. Differential scanning calorimetry (DSC) was used to determine the glass transition temperature of the particles, with Tg ranging from 45 °C to 56 °C (open vessel). Furthermore, particle experiments investigating the pigment content were conducted to improve the toner particle charge. It was found that toner formulations with a higher cyan pigment / carbon black pigment ratio exhibited a higher charge. This was observed in embodiments ranging from 1:20 to 1:1.5, and in embodiments ranging from 1:10 to 1:3.

Claims

Toner comprising a core and a shell, wherein the core comprises a resin comprising a first non-crosslinked polymer in combination with a crosslinked polymer, and at least one modified paraffin wax having branched carbon chains in combination with linear carbon chains, wherein the shell comprises a second non-crosslinked polymer present in an amount of 20% to 40% by weight of the toner, and wherein the branched carbon chains of the at least one modified paraffin wax are present in an amount of 1% to 20% of the at least one modified paraffin wax and have a molecular weight number average of 520 to 600, and wherein the linear carbon chains are present in an amount of 80% to 99% of the at least one modified paraffin wax and have a molecular weight number average of 505 to 530. Toner according to claim 1, wherein the first non-crosslinked polymer, the second non-crosslinked polymer or both comprise at least one monomer selected from the group consisting of styrenes, acrylates, methacrylates, butadienes, isoprenes, acrylic acids, methacrylic acids, acrylonitriles and combinations thereof; or wherein the first non-crosslinked polymer, the second non-crosslinked polymer or both are from the group consisting of poly(styrene-butadiene), poly(methyl methacrylate-butadiene), poly(ethyl methacrylate-butadiene), poly(propyl methacrylate-butadiene), poly(butyl methacrylate-butadiene), poly(methyl acrylate-butadiene), poly(ethyl acrylate-butadiene), poly(propyl acrylate-butadiene), poly(butyl acrylate-butadiene), poly(styrene-isoprene), poly(methyl styrene-isoprene), poly(methyl methacrylate-isoprene), poly(ethyl methacrylate-isoprene), poly(propyl methacrylate-isoprene), poly(butyl methacrylate-isoprene), poly(methyl acrylate-isoprene), poly(ethyl acrylate-isoprene), poly(propyl acrylate-isoprene),Poly(butyl acrylate isoprene), poly(styrene butyl acrylate), poly(styrene butadiene), poly(styrene butyl methacrylate), poly(styrene butyl acrylate acrylic acid), poly(styrene butadiene acrylic acid), poly(styrene isoprene acrylic acid), poly(styrene butyl methacrylate acrylic acid), poly(butyl methacrylate butyl acrylate), poly(butyl methacrylate acrylic acid), poly(styrene butyl acrylate acrylonitrile acrylic acid), poly(acrylonitrile butyl acrylate acrylic acid), and combinations thereof were selected. Toner according to claim 1, wherein the cross-linked polymer comprises at least one monomer selected from the group consisting of styrenes, acrylates, methacrylates, butadienes, isoprenes, acrylic acids, methacrylic acids, acrylonitriles and combinations thereof, wherein the cross-linked polymer is present in the toner in an amount of 6% to 14% by weight of the toner; or wherein the toner comprises a colorant, wherein the colorant comprises dyes, pigments, combinations of dyes, combinations of pigments and combinations of dyes and pigments, and wherein the toner further comprises at least one functional monomer selected from the group consisting of acrylic acid, beta-carboxyethyl acrylate, poly(2-carboxyethyl) acrylate, 2-carboxyethyl methacrylate and combinations thereof. Toner according to claim 1, wherein the branched carbon chains in the at least one modified paraffin wax have a mass-averaged molecular weight of 530 to 580, wherein the linear carbon chains in the at least one modified paraffin wax have a mass-averaged molecular weight of 480 to 550, and wherein the at least one modified paraffin wax is present in an amount of 2% by weight of the toner to 20% by weight of the toner; or wherein the branched carbon chains in the at least one modified paraffin wax have a number of carbon atoms of 31 to 59 and the linear carbon chains in the at least one modified paraffin wax have a number of carbon atoms of 24 to 54;or wherein the particles constituting the toner have a hot offset temperature of 135 °C to 220 °C, a size of 5 micrometers to 9 micrometers, a roundness of 0.900 to 0.999 and a surface area of ​​0.5 m2 / g to 1.4 m2 / g. Toner according to claim 2, wherein the second non-crosslinked polymer is present in an amount of 26% by weight of the toner to 36% by weight of the toner; and wherein the particles constituting the toner have a surface area of ​​0.5 m² / g to 1.4 m² / g. Toner according to claim 5, wherein the first non-crosslinked polymer and the second non-crosslinked polymer comprise at least one monomer selected from the group consisting of styrenes, acrylates, methacrylates, butadienes, isoprenes, acrylic acids, methacrylic acids, acrylonitriles and combinations thereof, wherein the toner comprises a colorant, wherein the colorant comprises dyes, pigments, dye combinations, pigment combinations and combinations of dyes and pigments, wherein the branched carbon chains in the at least one modified paraffin wax have a mass-averaged molecular weight of 530 to 580 and the linear carbon chains in the at least one modified paraffin wax have a mass-averaged molecular weight of 480 to 550, and wherein the at least one modified paraffin wax is present in an amount of 2% by weight of the toner to 20% by weight of the toner.or wherein the branched carbon chains in the at least one modified paraffin wax have a number of carbon atoms of 31 to 59 and the linear carbon chains in the at least one modified paraffin wax have a number of carbon atoms of 24 to 54, and wherein the particles constituting the toner have a hot offset temperature of 135 °C to 220 °C and a size of 5 micrometers to 9 micrometers. Toner according to claim 1 or 5, further comprising a cyan pigment in combination with an industrial carbon black pigment in a ratio of cyan pigment:industrial carbon black pigment of 1:20 to 1:1.

5. A method for producing toner particles comprising: contacting an emulsion comprising a first non-crosslinked polymer in combination with a crosslinked polymer with at least one modified paraffin wax having branched carbon chains in combination with linear carbon chains; wherein the branched carbon chains of the at least one modified paraffin wax are present in an amount of 1% to 20% of the at least one modified paraffin wax and have a molecular weight number average of 520 to 600, and wherein the linear carbon chains are present in an amount of 80% to 99% of the at least one modified paraffin wax and have a molecular weight number average of 505 to 530;Aggregating particles by contacting the particles with an aggregating agent in an amount of 0.1 parts per hundred to 0.25 parts per hundred to form aggregated particles; forming a shell over the aggregated particles by contacting the aggregated particles with an emulsion comprising a second non-crosslinked polymer, wherein the second non-crosslinked polymer is present in an amount of 20% to 40% by weight of the toner; and recovering the toner particles, wherein the toner particles have a roundness of 0.900 to 0.

999. The method of claim 8, wherein the branched carbon chains in the at least one modified paraffin wax have a number of carbon atoms of 31 to 59 and a mass-averaged molecular weight of 530 to 580, and the linear carbon chains in the at least one modified paraffin wax have a number of carbon atoms of 24 to 54 and a mass-averaged molecular weight of 480 to 550; or wherein the toner particles have a hot offset temperature of 135 °C to 220 °C and a size of 5 micrometers to 9 micrometers.

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