Tin oxide-polymer composite toner surface particles

Abstract

An example of a toner for developing an electrostatic charge image, the toner including a toner particle comprising a binder resin, a colorant, and a releasing agent, a first external additive disposed on the surface of the toner particle, the first external additive comprising strontium titanate particles, and a second external additive disposed on the surface of the toner particle, the second external additive comprising tin oxide-polymer composite particles.

Description

86311692 1 TIN OXIDE-POLYMER COMPOSITE TONER SURFACE PARTICLES BACKGROUND

[0001] Toner particles may be used to form an electrostatic latent image. For instance, an electrostatic charge image may be developed by a developer including a toner to be visualized as a toner image. This toner image may be transferred and fixed onto a surface of a recording medium to form a corresponding image.

[0002] Surface characteristics of toner particles can impact charging uniformity, charging stability, transferability, and / or a cleaning ability of the toner particles, among other qualities of the toner particles. An external additive may be added to a surface of a toner particle to alter surface characteristics of the toner particle. DETAILED DESCRIPTION

[0003] Surface characteristics of toner particles may affect charging uniformity, charging stability, transferability, and / or a cleaning ability of the toner particles. An external additive may be added to a surface of a toner particle to alter surface characteristics of the toner particle.

[0004] Some approaches may employ titanium dioxide particles and / or silica particles as surface additives. However, toner particles having titanium dioxide particles and / or silica particles as a surface additive may not exhibit charging uniformity. For example, fumed silica has a strong negative polarity and thus toner particles with fumed silica as a surface additive may exhibit excessive charge-up.

[0005] As such, some other approaches may add titanium dioxide particles, in addition to fumed silica particles, to mitigate frictional charging due to the excessive charge-up phenomenon caused by the presence of the fumed silica particles. However, since titanium dioxide has a low electric resistance and a good charge exchangeability, a reverse or weakly charged toner may be produced. Moreover, titanium dioxides may be costly to procure and / or the use of titanium dioxides may be disfavored and / or restricted, for instance, due to86311692 2 environmental concerns (e.g., pollution concerns, carcinogenic concerns), or for other reasons. Additionally, surface additives such as titanium dioxide, strontium oxide and / or polymer beads may have positive charge characteristics which may cause filming on the organic photoconductor (OPC) roller and / or contamination of the charge roller due to a strong adhesion of the surface additives to a surface of the charge roller or OPC roller through which a strong negative voltage flows.

[0006] Moreover, silica particles may be porous and / or have hydrophilic surfaces. Thus, if a toner particle with silica particles as a surface additive is used in a high-temperature and high-humidity environment, the toner particle may not be well charged due to excessive absorption of moisture, which may serve as an electrical conductor. On the other hand, a toner particle with silica particles as a surface additive may be excessively charged in a low-temperature and low-humidity environment. That is, charging stability of a toner particle with silica particles as a surface additive may vary and / or be deteriorated depending on environmental conditions (e.g., humidity and / or temperature).

[0007] To address the above-mentioned variance and / or deterioration in environmental charge stability (e.g., caused by moisture), silica particles and / or titanium dioxide particles may be treated with a surface treating agent such as hydrophobic silicone oil. However, using various surface treating agents may reduce flowability of the toner particles.

[0008] Use of small-diameter toner particles has been increased, for instance, to provide high image quality. However, the smaller the toner particle diameter, the more ineffective the flowability of the toner particles may become, and a greater quantity of inorganic particles may be required as an external additive. The external additive is exposed to friction against a supply roller and a blade or due to stirring within a developing unit during electrophotography. Stress exerted on the toner particle during this process may cause the external additive to be separated from the toner particle surface or to be buried in (e.g., embedded in) the toner particle surface. As a result, the toner particles may have ineffective flowability, may be unable to be smoothly supplied in an electrophotographic imaging system, and may have increased adhesion to a86311692 3 developing roller, resulting in sharp reductions in development characteristics and durability (e.g., charge retention).

[0009] The toner compositions herein can be employed in an electrophotographic imaging apparatus which has a charging roller and / or an electrophotographic cartridge. Examples of electrophotographic imaging apparatus include a printer, a copier, a scanner, a fax machine, or a multifunction peripheral incorporating two or more of these.

[0010] Tin oxide-polymer composite toner surface particles are described herein. In some examples, strontium titanate particles are added with the tin oxide-polymer composite particles to an external additive that is disposed on the surface of the toner particles. For instance, tin oxide-polymer composite toner surface particles and strontium titanate surface particles can provide enhanced surface characteristics of a toner particle when disposed on a surface of toner particle and thus can provide resultant toner compositions that exhibit enhanced performance (e.g., charge retention, thermal stability, etc.) as compared to other approaches such as those that employ silica particles (e.g., sol-gel silica powder) and / or titanium dioxide particles. The toner compositions herein can be used to develop an electrostatic latent image, as described herein.

[0011] Notably, the above-mentioned enhanced surface characteristics can be realized in the absence of (without the presence of) titanium dioxide (e.g., TiO2), strontium oxide, and / or polymer beads. Stated differently, the toner composition herein can be titanium dioxide-free (e.g., including 0 percent titanium dioxide by weight of a total weight of the toner composition), sol-gel silica powder-free, strontium oxide-free, and polymer beads-free, and thus can avoid incurring any cost, performance characteristic reduction, and / or environmental impact associated with use of titanium dioxide, sol-gel silica, strontium oxide, and / or polymer beads.

[0012] The toner compositions herein include toner particles (core particles) and an additive disposed on an external surface of the toner particles. The additive can include tin oxide-polymer composite particles and strontium titanate particles. In some examples, the additive can include tin oxide-polymer composite particles, strontium titanate particles, and fumed silica particles, as86311692 4 described herein.

[0013] Each of the toner particles includes a core particle including a binder resin, a pigment, and a releasing agent. Examples of the binder resin may include, but are not limited to, a styrenic resin, an acrylic resin, a vinyl resin or polyolefin resin, a polyether-based polyol resin, a phenolic resin, a silicone resin, a polyester resin, an epoxy resin, a polyimide resin, a polyurethane resin, a polybutadiene resin, or any mixture thereof.

[0014] Examples of the styrenic resin may include, but are not limited to, polystyrene, a homopolymer of a styrenic monomer such as poly-p- chlorostyrene or polyvinyltoluene, a styrene-based copolymer such as a styrene-p-chlorostyrene copolymer, a styrenevinyltoluene copolymer, a styrene- vinyl naphthalene copolymer, a styrene-acrylic acid ester copolymer, a styrene- methacrylic acid ester copolymer, a styrene-methyl achloromethacrylate copolymer, a styrene-acrylonitrile copolymer, a styrene-vinyl methyl ether copolymer, a styrene-vinyl ethyl ether copolymer, a styrene-vinyl methyl ketone copolymer, a styrene-butadiene copolymer, a styrene-isoprene copolymer, or a styrene-acrylonitrile-indene copolymer, or any mixture thereof.

[0015] Examples of the acrylic resin may include, but are not limited to, a polymer of acrylic acid, a polymer of methacrylic acid, a polymer of methyl methacrylate, a polymer of methyl -chloromethacrylate, or any mixture thereof.

[0016] Examples of the vinyl resin or polyolefin resin may include, but are not limited to, polyvinyl chloride, polyethylene, polypropylene, polyacrylonitrile, polyvinyl acetate, or any mixture thereof.

[0017] The polyester resin may be prepared via reaction between an aliphatic, alicyclic, or aromatic polybasic carboxylic acid or alkyl ester thereof and polyhydric alcohol via direct esterification or trans-esterification. Examples of the polybasic carboxylic acid may include phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylene-2-acetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, ophenylenediglycolic acid, diphenylacetic acid,diphenyl- -dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic86311692 5 acid, and / or cyclohexane dicarboxylic acid. Also, in addition to the dicarboxylic acid, a polybasic carboxylic acid such as trimellitic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, and pyrene tetracarboxylic acid may be used. Also, derivatives of a carboxylic acid in which the carboxylic group thereof is reacted to form an anhydride, oxychloride, or ester group may be used. Among them, terephthalic acid or lower esters thereof, diphenyl acetic acid, cyclohexane di- carboxylic acid, or the like may be used. The lower ester refers to an ester of aliphatic alcohol having one to eight carbon atoms. Examples of the polyhydric alcohol may include an aliphatic diol such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butane diol, hexane diol, neopentyl glycol, or glycerine, an alicyclic diol such as cyclohexane diol, cyclohexane dimethanol, or hydrogen-added bisphenol A, and an aromatic diol such as ethylene oxide adduct of bisphenol A or propylene oxide adduct of bisphenol A. One or more than one of the polyhydric alcohol may be used. Among these polyhydric alcohols, an aromatic diol and an alicyclic diol may be used. For example, an aromatic diol may be used. In addition, a polyhydric alcohol having three or more —OH groups, such as glycerin, trimethylol propane, or pentaerythritol may be used together with the diol to have a cross-linked structure or a branched structure to increase fixability or fusability of the toner.

[0018] A number average molecular weight of the binder resin may be in the range of about 700 to about 1,000,000 g / mole (mol) or about 10,000 to about 500,000 g / mol. The binder resin used in the present disclosure may include a combination of a high molecular weight binder resin and a low molecular weight binder resin in an appropriate ratio. A number average molecular weight of the high molecular weight binder resin may be, for example, from about 100,000 to about 500,000 g / mol, and a number average molecular weight of the low molecular weight binder resin may be, for example, from about 1,000 to about 100,000 g / mol. The two types of binder resins having different molecular weights may have independent functions. For instance, the low molecular weight binder resin has little molecular chain entanglements, and may thereby contribute to fusability and gloss. On the contrary, the high molecular86311692 6 weight binder resin may maintain a certain level of elasticity even at a high temperature due to many molecular chain entanglements, and may thereby contribute to a higher hot offset occurring temperature.

[0019] The pigment may be, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, or any combination thereof. For example, the black pigment may be carbon black, aniline black, or any mixture thereof.

[0020] For example, the yellow pigment may be a condensed nitrogen compound, an isoindolinon compound, an anthraquinone compound, an azo metal complex, an allyl imide compound, or any mixture thereof. More particularly, the yellow pigment may be, but is not limited to, “C.I. Pigment Yellow” 12, 13, 14, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, or 180.

[0021] For example, the magenta pigment may be a condensed nitrogen compound, an anthraquinone compound, a quinacridone compound, a base dye lake, a naphthol compound, a benzoimidazole compound, a thioindigo compound, a perylene compound, or any mixture thereof. More particularly, the magenta pigment may be, but is not limited to, “C.I. Pigment Red” 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, or 254.

[0022] For example, the cyan pigment may be a copper phthalocyanine compound or a derivative thereof, an anthraquinone compound, a base dye lake, or any mixture thereof. More particularly, the cyan pigment may be, but is not limited to, “C.I. Pigment Blue” 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, or 66.

[0023] The amount of the pigment included in the core particle may be, for example, from about 0.1 parts by weight to about 20 parts by weight, for example, from about 2 parts by weight to about 10 parts by weight, based on 100 parts by weight of the binder resin, without being limited thereto.

[0024] Examples of the releasing agent may include, but are not limited to, a polyethylene-based wax, a polypropylene-based wax, a silicone-based wax, a paraffin-based wax, an ester-based wax, a carnauba-based wax, a metallocene-based wax, or any mixture thereof.86311692 7

[0025] The releasing agent may have, for example, a melting point of from about 50 °C to about 150 °C, without being limited thereto. The amount of the releasing agent included in the core particle may be, for example, from about 1 part by weight to about 20 parts by weight, or from about 1 part by weight to about 10 parts by weight, based on 100 parts by weight of the binder resin. The releasing agent may prevent the toner particles from sticking to a heating roller of a fixing device.

[0026] The core particles may be prepared by, for example, a pulverization process, an aggregation process, or a spraying process. The pulverization process may be performed by, for example, pulverizing after melting and mixing a binder resin, a pigment, and a releasing agent. The aggregation process may be performed by, for example, mixing a binder resin dispersion, a pigment dispersion, and a releasing agent dispersion; aggregating these particles of the binder resin, the pigment, and the releasing agent; and combining the resulting aggregates.

[0027] A volume average particle diameter of the core particles may be, but is not limited to, from about 4 m to about 20 m or from about 5 m to about 10 m.

[0028] A shape of the core particles is also not particularly limited. As the shape of the core particles is closer to a sphere, charging stability of the toner and dot reproducibility of a print image may be more enhanced. For example, the core particles may have a sphericity in a range of, for example, about 0.90 to about 0.99. The sphericity of the core particles can be measured by a flow particle image analyzer, FLOWCAMTM8000 manufactured by YOKOGAWA Corp.TMusing an analysis software (VISUALSPREADSHEETTMsuch as version 5.9.1.78). Specifically, in a 100 milliliter (mL) glass beaker, 0.1 mL to 0.5 mL of a surfactant, preferably Benzene, 1,1-oxybis, tetrapropylene derivatives, sulfonated, sodium salts (DOWFAXTM2A1 manufactured by THE DOW CHEMICAL CO., LTD.TM) is loaded, approximately 0.1 gram (g) to 0.5 g of each toner is further added and stirred with a micro spatula, and then 80 mL of ion- exchanged water is added. Next, the obtained dispersion liquid is dispersed by an ultrasonic dispersion for about 3 minutes. The shape and distribution of the86311692 8 toner are measured using FLOWCAMTM8000, until the number of analyzed particles in the dispersion reaches 30,000.

[0029] External additives can be attached to a surface of the core particles. As described herein, it has been discovered that having tin oxide- polymer composite particles (e.g., tin oxide-polymer composite toner surface particles) and strontium titanate particles (e.g., strontium titanate toner surface particles) attached to surface of a core particle provides a resultant toner composition exhibiting good charging properties (charge retention rate, charge decrease rate, charging rate, and charging speed), exhibiting good image characteristics (e.g., good image background performance), and exhibiting good long-term thermal stability, as described herein.

[0030] In some examples, the tin oxide-polymer composite particles can have an average particle diameter in a range from about 60 nanometers (nm) to about 150 nm. All individual values from about 60 nm to about 150 nm are included. For instance, the tin oxide-polymer composite particles can have an average particle diameter in a range from 75 nm to 100 nm or in a range from 60 nm to 120 nm. In some examples, the tin oxide-polymer composite particles can have an average particle diameter of about 60 nm, about 70 nm, about 80 nm, about 90 nm, about 100 nm, about 110 nm, about 120 nm, about 130 nm, about 140 nm, or about 150 nm, among other possible values. As used herein, the average particle diameter refers to or includes the diameter of a spherical particle, or the average diameter of a non-spherical particle (e.g., the average of multiple diameters across the non-spherical particle). The average particle diameter of particles may be measured by a particle diameter distribution measuring device (manufacturer: MICROTRACTM, trade name: NANOTRAC FLEX).

[0031] In some examples, the strontium titanate particles can have an average particle diameter in a range from about 25 nm to about 40 nm. All individual values from about 25 nm to about 40 nm are included. For instance, the strontium titanate particles can have an average particle diameter in a range from 25 nm to 30 nm or in a range from 35 nm to 40 nm. In some examples, the strontium titanate particles can have an average particle diameter of about 2586311692 9 nm, about 30 nm, about 35 nm, or about 40 nm, among other possible values. As used herein, the average particle diameter refers to or includes the diameter of a spherical particle, or the average diameter of a non-spherical particle (e.g., the average of multiple diameters across the non-spherical particle). The average particle diameter of particles may be measured by a particle diameter distribution measuring device (manufacturer: MICROTRACTM, trade name: NANOTRAC FLEX). In some embodiments, the strontium titanate particles can have a particle circularity that are equal to or less than 0.940.

[0032] The tin oxide-polymer composite particles can be present in an amount to cover 16 percent to 33 percent of a total surface area of an external surface of a toner particle and the strontium titanate particles can be present in an amount to cover 27 percent to 65 percent of the total surface area of the external surface of the toner particle. All individual values and sub-ranges from about 16 percent to about 33 percent and from about 27 percent to about 65 percent are included. For instance, in some examples, the tin oxide-polymer composite particles can be present in an amount to cover 21 percent to 31 percent, 16 percent to 24 percent, 16 to 27 percent, or 16 percent to 33 percent of the total surface area of the external surface of the toner particle, among other possibilities. In some examples, the strontium titanate particles can be present in an amount to cover 45 percent to 50 percent, 27 percent to 36 percent, 55 percent to 65 percent, or 27 to 65 percent of the total surface area of the external surface of the toner particle, among other possibilities.

[0033] In some examples, the tin oxide-polymer composite particles can be present in a range from about 2.0 weight percent to about 4.0 weight percent of a total weight of the toner particle. As used herein, a total weight of the toner particle refers to a total weight of the toner particle prior to an additive being disposed on the surface of the toner particle. All individual values and sub- ranges from about 2.0 weight percent to about 4.0 weight percent are included. For instance, the tin oxide-polymer composite particles can be present in a range from about 2.0 weight percent to about 3.0 weight percent, a range from about 2.5 weight percent to about 3.5 weight percent, or a range from about 3.5 weight percent to 4.0 weight percent of a total weight of the toner particle. In86311692 10 some examples, the tin oxide-polymer composite particles can be present at 2.0 weight percent, 2.5 weight percent, 3.0 weight percent, 3.5 weight percent, or 4.0 weight percent of a total weight of the toner particle, among other possibilities.

[0034] In some examples, the strontium titanate particles can be present in a range from about 0.5 weight percent to about 1.0 weight percent of a total weight of the toner particle. All individual values and sub-ranges from about 0.5 weight percent to about 1.0 weight percent are included. For instance, the strontium titanate particles can be present in a range from about 0.5 weight percent to about 0.7 weight percent, a range from about 0.5 weight percent to about 1.0 weight percent, or a range from about 0.6 weight percent to 0.9 weight percent of a total weight of the toner particle. In some examples, the strontium titanate particles can be present at 0.5 weight percent, 0.6 weight percent, 0.7 weight percent, 0.8 weight percent, 0.9 weight percent, or 1.0 weight percent of a total weight of the toner particle, among other possibilities.

[0035] In some examples, the tin oxide-polymer composite particles can include a polymer composite core with a layer of tin oxide. In some embodiments, the tin oxide polymer composite particles can include a polymer mother particle. As used herein, the polymer mother particle refers to a central framework to which other materials (such as inorganic nanoparticles, other polymers, or functional additives) are bound or attached, creating a composite with properties distinct from the original components. Utilizing a polymer composite particle with a polymer mother particle can be used to enhance mechanical strength, thermal stability, electrical conductivity, or other properties of the material. In some examples, the polymer mother particles of the tin oxide- polymer composite comprises one of a polystyrene (PS) particle, a polymethyl methacrylate (PMMA) particle, or a polyester (PE) particle. Although specific polymer mother particles for the tin oxide-polymer composite particles are described herein, other polymer mother particles can be utilized in a similar way.

[0036] In some embodiments, the toner including the tin oxide-polymer composite particles and strontium titanate particles can be tested for X-ray fluorescence (XRF) intensity. In some embodiments, the XRF can refer to the86311692 11 measure of the strength or brightness of the X-ray signals emitted from a material when it is irradiated with high-energy X-rays or gamma rays. In some embodiments, the XRF intensity of particles may be measured by a XRF measuring device (manufacturer: SHIMAZUTM, model: lab center XRF-1800).

[0037] In some embodiments, a XRF intensity of the tin oxide-polymer composite particles of the toner is in a range from 40 kilo counts per second (kcps) to 90 kcps. All individual values and sub-ranges from about 40 kcps to about 90 kcps are included. For instance, the tin oxide-polymer composite particles can XRF intensity values in a range from about 40 kcps to about 50 kcps, a range from about 70 kcps to about 90 kcps, or a range from about 50 kcps to about 70 kcps. In some examples, the tin oxide-polymer composite particles can have a XRF intensity at 40 kcps, 50 kcps, 60 kcps, 70 kcps, 80 kcps, or 90 kcps, among other possibilities.

[0038] In some embodiments, a XRF intensity of the strontium titanate particles of the toner is in a range from 1250 kcps to 1650 kcps. All individual values and sub-ranges from about 1250 kcps to about 1650 kcps are included. For instance, the strontium titanate particles can XRF intensity values in a range from about 1250 kcps to about 1450 kcps, a range from about 1550 kcps to about 1650 kcps, or a range from about 1350 kcps to about 1450 kcps. In some examples, the strontium titanate particles can have a XRF intensity at 1250 kcps, 1350 kcps, 1450 kcps, 1550 kcps, or 1650 kcps, among other possibilities.

[0039] In some embodiments, a XRF intensity ratio of the tin oxide- polymer composite particles to silica ratio of the toner is in a range of 60 to 150 and a XRF intensity ratio of the strontium titanate particles to silica ratio of the toner is in a range of 1800 to 2500.

[0040] In some embodiments, the tin oxide-polymer composite particles and strontium titanate particles can be added as a dosage percentage of the toner composition. As used herein, a dosage percentage refers to a representation of the amount of the ingredient per 100 units of the total volume or weight of the mixture. For example, the dosage percentage can be calculated utilizing an amount of an active ingredient over a total volume of the mixture where the value is multiplied by 100.86311692 12

[0041] In some embodiments, a dosage percentage of tin oxide-polymer composite particles is in a range from 2.0 percent to 4.0 percent of the toner composition. All individual values and sub-ranges from about 2.0 percent to about 4.0 percent are included. For instance, the tin oxide-polymer composite particles can be present in a range from about 2.0 percent to about 3.0 percent, or a range from about 3.0 percent to 4.0 percent of a total weight of the toner particle. In some examples, the tin oxide-polymer composite particles can be present at 2.0 percent, 2.5 percent, 3.0 percent, 3.5 percent, or 4.0 percent of a total weight of the toner particle, among other possibilities.

[0042] In some embodiments, a dosage percentage of strontium titanate particles is in a range from 0.5 percent to 1.0 percent of the toner composition. All individual values and sub-ranges from about 0.5 percent to about 1.0 percent are included. For instance, the strontium titanate particles can be present in a range from about 0.5 percent to about 0.7 percent, or a range from about 0.7 percent to 1.0 percent of a total weight of the toner particle. In some examples, the strontium titanate particles can be present at 0.5 percent, 0.6 percent, 0.7 percent, 0.8 percent, 0.9 percent, or 1.0 percent of a total weight of the toner particle, among other possibilities.

[0043] In some embodiments, the additive further comprises fumed silica particles. Fumed silica particles can be utilized as an external additive to the toner composition to improve the flow properties and charging characteristics of the toner powder. In some embodiments, fumed silica can have a relative size of about 6 nm to 20 nm. In some specific embodiments, the fumed silica can have a relative size of about 12 nm.

[0044] In some embodiments, a dosage percentage of fumed silica particles is in a range from 0.5 percent to 1.5 percent of the toner composition. In a specific example, the fumed silica particles has a dosage percentage of about 1.0 percent of the toner composition. All individual values and sub-ranges from about 0.5 percent to about 1.5 percent are included. For instance, the fumed silica particles can be present in a range from about 0.5 percent to about 0.7 percent, or a range from about 0.7 percent to 1.5 percent of a total weight of the toner particle. In some examples, the fumed silica particles can be present86311692 13 at 0.5 percent, 0.6 percent, 0.7 percent, 0.8 percent, 0.9 percent, 1.0 percent, 1.1 percent, 1.2 percent, 1.3 percent, 1.4 percent, or 1.5 percent of a total weight of the toner particle, among other possibilities.

[0045] In some embodiments, the tin oxide-polymer composite particles are treated with a hydrophobic silane coupling agent. As used herein, a hydrophobic silane coupling agent refers to a chemical compound used to modify surface properties of materials and / or organic polymers. Silane coupling agents are organosilicon compounds that typically have two functional groups: one that can bond with an inorganic substrate and another that is compatible with organic materials. The hydrophobic nature of these agents means that, once applied, they can significantly reduce the surface's affinity for water.

[0046] In some examples, enhanced performance characteristics (good charge retention, good charge decrease, good environmental charge stability, good image background performance, good charging speed, and / or good thermal stability, etc.) of the toner compositions with tin oxide-polymer composite particles and strontium titanate particles can be realized in the absence of (having 0.0 weight percent based on a total weight of a toner composition) titanium dioxide, strontium oxide, sol-gel silica, and / or polymer beads. Stated differently, the toner composition herein can be titanium dioxide- free, strontium oxide-free, sol-gel silica powder and polymer beads-free, and thus can avoid incurring a cost, performance characteristic reductions, and / or environmental impacts associated with use of titanium dioxide, strontium oxide, sol-gel silica, and / or polymer beads.

[0047] The external additive particles such as the tin oxide-polymer composite particles and strontium titanate particles may be attached to the surfaces of the core particles of the toner by using, for example, a powder mixing apparatus without being limited thereto. Examples of the powder mixing apparatus may be, but are not limited to, a HENSCHELTMmixer, a V shape mixer, a ball mill, or a NAUTATMmixer.

[0048] In some examples, the toner compositions herein can exhibit a charge retention satisfying the condition R2 / R1 greater than 0.8, where: R1 is an initial charge per an amount of the toner composition; and R2 is a charge per86311692 14 the amount of the toner composition measured after printing 300,000 sheets with the toner composition, as described herein.

[0049] In some examples, the toner compositions herein can exhibit a charge decrease satisfying the condition R2 / R1 greater than 0.8, where: R1 is an initial charge per an amount of the toner composition at ambient conditions, and R2 is a charge per amount of toner after the toner is maintained under high- temperature and high-humidity (HH) condition (30° C., relative humidity of 80% for 48 hours), as described herein.

[0050] In some examples, the toner compositions herein can exhibit an environmental charging stability satisfying the condition high humidity (HH) / low humidity (LL) of 0.8 to 1.0, wherein high temperature / humidity (HH) performance of the toner composition is measured after the toner composition is maintained at 50° C and a relative humidity of 80% for 48 hours and the low temperature / humidity (LL) performance of the toner composition is measured after the toner composition is maintained at 10° C and a relative humidity of 10%, as described herein.

[0051] In some examples, the toner compositions herein can exhibit an image background performance satisfying the condition where the optical density is less than 0.02, as described herein.

[0052] In some examples, the toner compositions herein can exhibit a charging speed performance satisfying the condition where charging density is in a range from 1.0 to 2.0, as described herein.

[0053] In some examples, the toner compositions herein can exhibit a thermal stability performance satisfying the condition where the cohesion is less than 25, as described herein.

[0054] An electrophotographic imaging apparatus in accordance with the present disclosure may include an electrophotographic cartridge. The electrophotographic cartridge may include an electrophotographic photoconductor drum that is charged by a charging roller according to an example, which is a charging means disposed in contact with the electrophotographic photoconductor drum. The electrophotographic photoconductor drum may be rotationally driven at a predetermined86311692 15 circumferential speed about an axis. The electrophotographic photoconductor drum may be subjected to uniform charging of a positive or a negative predetermined potential on its surface by the charging roller in the rotation process. The voltage applied to the charging roller may be, for example, a DC voltage. However, the voltage applied to the charging roller may be, for example, a combination of an AC voltage and a DC voltage. In the electrophotographic imaging apparatus according to an example, even when a DC voltage is applied to the charging roller, stable charging characteristics may be maintained for a longer period of time, and a high-quality output image may be obtained.

[0055] The charging roller may charge the surface of the electrophotographic photoconductor drum to a uniform potential value while rotating in contact with the electrophotographic photoconductor drum. The image portion is exposed by laser light to form an electrostatic latent image on the electrophotographic photoconductor drum. After the electrostatic latent image is made a visible image, for example, a toner image, by a developing unit, the toner image is transferred to an image receiving member such as paper by a transfer unit such as the transfer roller to which a voltage is applied. Toner remaining on a surface of the electrophotographic photoconductor drum after the image transfer is cleaned by a cleaning unit, for example, a cleaning blade. The electrophotographic photoconductor drum may be used again for image formation. The developing unit includes a regulating blade, a developing roller, and a supply roller.

[0056] The electrophotographic cartridge according to an example may integrally support the electrophotographic photoconductor drum, the charging roller, and the cleaning blade, may be attached to the electrophotographic imaging apparatus, and may be detached from the electrophotographic imaging apparatus. Another cartridge may integrally support the developing unit including the regulating blade, the developing roller, and the supply roller, may be attached to the electrophotographic imaging apparatus, and may be detached from the electrophotographic imaging apparatus. Toner compositions such as those described herein (e.g., toner) may be located inside the86311692 16 developing unit.

[0057] Examples

[0058] Hereinafter, various examples will be described. However, the scope of the disclosure is not limited thereto.

[0059] Formation of toner compositions of Examples 1 to 5 and Comparative Examples 1 to 6:

[0060] The types and properties of the surface additives (SA) and the toner particles used in Examples 1 to 5 and Comparative Examples 1 to 6 are described below.

[0061] The toner particles for each of Examples 1 to 5 and Comparative Examples 1 to 6 are available from XEROXTM.

[0062] Different additives were added in the amounts shown in Tables 1A and 1B to an external surface of the toner particles to form the toner compositions of Examples 1 to 5 and Comparative Examples 1 to 6.

[0063] The surface additives are described as follows:

[0064] Surface additive 1 (SA 1): Tin oxide-polymer composite particles having an average particle diameter of 120 or 80 nanometers, as indicated in Table 1A. SA 1 is available from TITAN KOGYO LTDTM.

[0065] Surface additive 2 (SA 2): Strontium titanate particles having an average particle diameter of 25 nanometers, as indicated in Table 1A. SA 2 is available from TITAN KOGYO LTDTM.

[0066] Surface additive 3 (SA 3): Fumed silica particles having an average particle diameter of 12 nanometers, as indicated in Table 1A. SA 3 additive is available from EVONIK INDUSTRIES AGTM.

[0067] Surface additive 4 (SA 4): Sol-gel silica particles having an average particle diameter of 110 nanometers, as indicated in Table 1B. SA 4 additive is available from SHIN-ETSU CHEMICAL CO., LTDTM.

[0068] Surface additive 5 (SA 5): Titanium dioxide particles having an average particle diameter of 30 nanometers, as indicated in Table 1B. SA 5 is available from TITAN KOGYOTM.

[0069] The type and amounts of surface additive(s), as indicated in Tables 1A and 1B, were added to the surface of the toner particles by mixing the86311692 17 toner particles and the surface additives using Powder mixer (Model (LS-2K) made by DAEWHA Tech GlobalTM) at 6000 rpm for 180 seconds to obtain the toner compositions of the examples and comparative examples.

[0070] Example 1 (EX 1): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 120 nm) was added at a dosage percentage of 2.0 percent of the toner composition, SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 0.5 percent of the toner composition, and SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition.

[0071] Example 2 (EX 2): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 120 nm) was added at a dosage percentage of 4.0 percent of the toner composition, SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 1.0 percent of the toner composition, and SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition.

[0072] Example 3 (EX 3): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 80 nm) was added at a dosage percentage of 2.0 percent of the toner composition, SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 0.5 percent of the toner composition, and SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition.

[0073] Example 4 (EX 4): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 80 nm) was added at a dosage percentage of 4.0 percent of the toner composition, SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 1.0 percent of the toner composition, and SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition.

[0074] Example 5 (EX 5): SA 1 (Tin oxide-polymer composite particles86311692 18 having an average particle diameter of 80 nm) was added at a dosage percentage of 4.0 percent of the toner composition, SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 0.5 percent of the toner composition, and SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition.

[0075] Comparative Example 1 (CE 1): SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 0.5 percent of the toner composition, SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition, and SA4 (Sol-gel silica particles having an average particle diameter of 110 nanometers) was added at a dosage percentage of 2.0 percent of the toner composition.

[0076] Comparative Example 2 (CE 2): SA2 (Strontium titanate particles having an average particle diameter of 25 nm) was added at a dosage percentage of 1.0 percent of the toner composition, SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition, and SA4 (Sol-gel silica particles having an average particle diameter of 110 nanometers) was added at a dosage percentage of 4.0 percent of the toner composition.

[0077] Comparative Example 3 (CE 3): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 120 nm) was added at a dosage percentage of 4.0 percent of the toner composition, SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition and SA5 (Titanium dioxide particles having an average particle diameter of 30 nanometers) was added at a dosage percentage of 0.5 percent of the toner composition.

[0078] Comparative Example 4 (CE 4): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 120 nm) was added at a dosage percentage of 4.0 percent of the toner composition, SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition and SA5 (Titanium86311692 19 dioxide particles having an average particle diameter of 30 nanometers) was added at a dosage percentage of 1.0 percent of the toner composition.

[0079] Comparative Example 5 (CE 5): SA 1 (Tin oxide-polymer composite particles having an average particle diameter of 80 nm) was added at a dosage percentage of 4.0 percent of the toner composition, SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition and SA5 (Titanium dioxide particles having an average particle diameter of 30 nanometers) was added at a dosage percentage of 0.5 percent of the toner composition.

[0080] Comparative Example 6 (CE 6): SA 3 (fumed silica particles having an average particle diameter of 12 nm) was added at a dosage percentage of 1.0 percent of the toner composition, SA4 (Sol-gel silica particles having an average particle diameter of 110 nanometers) was added at a dosage percentage of 4.0 percent of the toner composition, and SA5 (Titanium dioxide particles having an average particle diameter of 30 nanometers) was added at a dosage percentage of 1.0 percent of the toner composition.

[0081] Table 1A

[0082] Table 1B86311692 20

[0083] The XRF intensity results for the toner compositions of Examples 1-5 and Comparative Examples 1-6 are summarized in Table 2.

[0084] Table 2: Examples (EX) and Comparative Examples (CE)

[0085] The evaluation results of the toner compositions of Examples 1-5 and Comparative Examples 1-6 are summarized in Table 3.

[0086] Table 3: Examples (EX) and Comparative Examples (CE)86311692 21

[0087] X-ray fluorescence (XRF) Intensity

[0088] Evaluation was performed using a SHIMAZUTMLab Center XRF- 1800 as a measuring device. Approximately 2.5 grams (g) of toner composition was utilized to generate a pellet and analyzed by the XRF measuring device.

[0089] Environmental Charging Stability (charging property):

[0090] The electric field separation (q / m) meter was used as a measuring device, and the following procedure was performed under the voltage 3.0 kilovolts (kV) condition.

[0091] 1.4 g of a toner composition and 18.6 g of a carrier were added to a 50 ml bottle and mixed using a TURBULARTMmixer for about 180 seconds to prepare a toner composition sample. The toner composition sample was maintained under a low-temperature and low-humidity (LL) condition (10° C., relative humidity of 10%) and a high-temperature and high-humidity (HH) condition (30° C., relative humidity of 80% for 48 hours), respectively. Then, charging performance thereof was evaluated to measure a charge amount in each environment and charging stability was evaluated according to the following criteria.86311692 22

[0092] A: Charge amount ratio of HH / LL of 0.8 to 1.0 (Excellent state in which almost no difference between charge amounts in different environmental conditions was found);

[0093] B: Charge amount ratio HH / LL of 0.7 to less than 0.8 (Good state in which a small difference between charge amounts in different environmental conditions was found); and

[0094] C: Charge amount ratio of HH / LL of less than 0.7 (Acceptable state in which a large difference between charge amounts in different environmental conditions was found).

[0095] D: Charge amount ratio of HH / LL of less than 0.6 or less (Bad state in which a very large difference between charge amounts in different environmental conditions was found)

[0096] Charge retention rate:

[0097] The electric field separation q / m meter was used as a measuring device, and the following procedure was performed under the voltage 3.0kV condition.

[0098] 1.4 g of a toner composition and 18.6 g of a carrier were added to a 50 ml bottle and mixed using a TURBULARTMmixer for about 180 seconds to prepare a toner composition sample. An amount of the toner composition was evaluated at initial conditions “R1” (measured at 50° Celsius (C.), relative humidity of 80% prior to printing any sheets with the toner composition) using the EPPINGTMq / m matter and at subsequent conditions “R2” (50° C., relative humidity of 80% after printing 300,000 sheets with the toner composition sample) using the following criteria:

[0099] A: R2 / R1 > 0.8 (Good charge retention);

[0100] B: R2 / R1 > 0.6 (Poor charge retention); and

[0101] C: R2 / R1 > 0.4 (Very poor charge retention).

[0102] Image background (organic photoconductor (OPC) roller background performance):

[0103] Since the background image is generated under printing conditions with high temperature / high humidity, the above test was conducted under high temperature / high humidity conditions. After each of the toner86311692 23 compositions of the examples and comparative examples were loaded into a toner cartridge of a two-component development system printer (E87770, available from HPTM) and 7K images with 2% coverage were printed at 30 degrees Celsius and 80% humidity. An average image background was determined by measuring the optical density reading at three non-image locations of the OPC drum. Each optical density reading was measured using a Spectro-Eye X-RITE: CH-8105 reflection densitometer. Image background performance was classified according to the following criteria.

[0104] A: less than 0.02 optical density (the toner composition has very good OPC background performance).

[0105] B: optical density of 0.02 or more and less than 0.03 (the toner composition has good OPC background performance).

[0106] C: optical density of 0.03 or more and less than 0.05 (the toner composition has poor OPC background performance).

[0107] D: optical density of 0.05 or more (the toner composition has very poor OPC background performance).

[0108] Thermal stability:

[0109] The toner particle was left for 16 hours in an environment with a temperature of 53 °C and a humidity of 80 relative humidity. For the degree of cohesion, POWDER TESTER (PT-S: manufactured by HOSOKAWA Co., Ltd.TM, sieve 53(A), 45(B), 38(C) micrometers ( m)) was used. Sieves were set inthe order of 53 m, 45 m, and 38 m from the top.2 g of toner particles were placed on the top sieve, and the mass of the toner particles remaining on each sieve when the sieve was vibrated was measured. The degree of aggregation was calculated according to the following formula (amplitude 1 millimeter (mm), vibration time 40 seconds). After standing at 53 °C for 16hr, the amount of change was measured according to each sieve under the above conditions to calculate the toner's thermal stability.

[0110] Cohesion = (A + B × (3 / 5) + C × (1 / 5)) × 100 / Toner mass (2g)

[0111] In the formula, A is the mass of the toner particles remaining on the upper sieve, B is the mass of the toner particles remaining on the mid sieve, and C is the mass of the toner particles remaining on the lower sieve. The ratio86311692 24 of the degree of cohesion after being left for 16 hours.

[0112] Thermal stability performance was classified according to the following criteria:

[0113] A: cohesion less than 25;

[0114] B: cohesion less than or equal to 35; and

[0115] C: cohesion greater than 35.

[0116] When the cohesion ratio is less than 25, it was determined that the heat-resistant storage property was good.

[0117] Transfer property

[0118] The transfer efficiency evaluation was divided into a first condition and a second condition as follows. The first condition transfer efficiency was measured using the weight of toner per unit area on an organic photoconductor (OPC) roller and the weight ratio of toner per unit area on intermediate transfer unit (ITB) after transfer of toner from OPC to intermediate transfer unit. In addition, the second condition transfer efficiency was evaluated using the weight ratio of toner per unit area on intermediate transfer unit and the weight ratio of toner per unit area on paper. At this time, the weight of toner per unit area on the paper was measured by using unfused images. The weight of the toner per unit area on the paper was measured by a balance.

[0119] Measuring conditions included:

[0120] A first condition--(toner mg on ITB / toner mg on OPC) x 100

[0121] A second condition--(toner mg on paper / toner mg on ITB) x 100

[0122] Transfer property efficiency was classified by the following evaluation criteria:

[0123] – average transfer efficiency of 90% or more

[0124] – average transfer efficiency between 85% and 90%

[0125] – average transfer efficiency between 80% and 85%

[0126] X – average transfer efficiency less than 80%

[0127] Image gloss

[0128] At a standard specified concentration of toner composition, a gloss meter (BYK gardner Gmbh) was utilized to evaluate a 60-degree standard gloss measurement. The evaluation was performed based on the Double A 80 gms86311692 25 paper. A E87770 A3 color machine can be utilized to generate printed paper with red-green-blue (RGB) and cyan-magenta-yellow-black (CMYK) images. This gloss data can be calculated by the average of all of the patches generated by the color machine.

[0129] Evaluation of image gloss performance are as follows:

[0130] – image gloss of 8.0 or more

[0131] – image gloss of 7.0 or more

[0132] – image gloss of 6.0 or more

[0133] X – image gloss of 6.0 or less

[0134] Referring to Tables 1A, 1B, 2, and 3 it was observed that the toner compositions of Examples 1 to 5 each have good charge retention, good environmental charge stability, good image background performance, good thermal stability, good transfer property, and good image gloss.

[0135] A reason for the above performance may be that the tin oxide- polymer composite particles in combination with the strontium titanate particles provide a reduction in an amount of friction when printing with the toner particles and / or provide more effective charging characteristics (e.g., as compared to the toner (core) particles alone and / or toner particles using different surface additives). Additionally, unlike other additives which may be prone to caking on and / or embedding in the surface of a toner particles, the tin oxide-polymer composite and strontium titanate surface additives herein may provide enhanced charging characteristics over an operational lifetime of an image forming apparatus and / or for various different environmental conditions (e.g., for both high humidity and low humidity environments). Further, the tin oxide- polymer composite particles in combination with the strontium titanate particles described herein can yield good charge retention, good charge decrease, good environmental charge stability, good image background performance, good charging speed, and / or good thermal stability, as compared to other approaches that may employ titanium oxide surface additives, which can be considered a hazardous substance to humans.

[0136] Although examples of the disclosure have been illustrated and described hereinabove, the disclosure is not limited thereto, and may be86311692 26 variously modified and altered by those skilled in the art to which the disclosure pertains without departing from the disclosure. These modifications and alterations are to fall within the scope of the disclosure. As used herein the term “about” refers to value(s) that are within 10 percent, within 5 percent or within 1 percent of a given value that the term about modifies. For instance, the term about can refer to a value(s) that are within 10 percent (+ / - 10 percent) of a given value.

Claims

86311692 27 WHAT IS CLAIMED IS:

1. A toner for developing an electrostatic charge image, the toner comprising: a toner particle comprising a binder resin, a colorant, and a releasing agent; a first external additive disposed on a surface of the toner particle, the first external additive comprising strontium titanate particles; and a second external additive disposed on the surface of the toner particle, the second external additive comprising tin oxide-polymer composite particles.

2. The toner of claim 1, wherein the tin oxide-polymer composite particles have an average size in a range from 60 nanometers (nm) to 150nm.

3. The toner of claim 1, wherein the strontium titanate particles have an average size in a range from 10nm to 45nm.

4. The toner of claim 1, wherein, a polymer mother particles of the tin oxide- polymer composite comprises one of a polystyrene (PS) particle, a polymethyl methacrylate (PMMA) particle, or a polyester (PE) particle.

5. The toner of claim 1, wherein a particle circularity of the strontium titanate particles are equal to or less than 0.

940.

6. The toner of claim 1, wherein a X-ray fluorescence (XRF) intensity of the tin oxide-polymer composite particles of the toner is in a range from 40 kilo counts per second (kcps) to 90kcps.

7. The toner of claim 1, wherein a XRF intensity of the strontium titanate particles of the toner is in a range from 1250kcps to 1650 kcps.

8. The toner of claim 1, wherein a XRF intensity ratio of the tin oxide-86311692 28 polymer composite particles to silica ratio of the toner is in a range of 60 to 150 and a XRF intensity ratio of the strontium titanate particles to silica ratio of the toner is in a range of 1800 to 2500.

9. The toner of claim 1, wherein the tin oxide-polymer composite particles are treated with a hydrophobic silane coupling agent.

10. A toner composition comprising: a silica toner particle including a binder resin, a releasing agent, and a pigment; and an additive disposed on an external surface of the silica toner particle, the additive comprising: strontium titanate particles having an average size in a range from 25 nanometers (nm) to 40nm; and tin oxide-polymer composite particles having an average size in a range from 110nm to 125nm.

11. The toner composition of claim 10, wherein a dosage percentage of tin oxide-polymer composite particles is in a range from 2.0 percent to 4.0 percent of the toner composition.

12. The toner composition of claim 10, wherein a dosage percentage of strontium titanate particles is in a range from 0.5 percent to 1.0 percent of the toner composition.

13. The toner composition of claim 10, comprising no titanium oxide within the additive or on the silica toner particle.

14. The toner composition of claim 10, wherein the additive further comprises fumed silica particles.

15. An image forming apparatus to form an image by supplying the toner86311692 29 composition according to claim 10.

Images