Toner

Abstract

To provide a toner which offers superior low-temperature fixability, heat resistance stability and electrostatic offset resistance, and is less likely to cause back stains.SOLUTION: A toner is provided, comprising core particles containing a binder resin and wax, and a shell formed on a surface of each core particle, where the wax contains a wax A and the shell contains a resin having a functional group B. The wax A has a surface charge density DA in a range of -0.0080 to -0.0025, and an absolute difference (|DA-DB|) between the surface charge density DA of the wax A and a surface charge density DB of the functional group B is 0.0025 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a toner used in an image forming method such as an electrophotographic method.

Background Art

[0002] Electrophotographic technology is a technology that forms an electrostatic latent image on a uniformly charged photoreceptor and visualizes the image information with charged toner, and is used in devices such as copiers and printers. In recent years, copiers and printers have been used in new market regions, and it is required to stably provide high-quality images for use in various environments. On the other hand, for toner, further improvement in low-temperature fixability is required from the viewpoints of high speed and energy saving. In Patent Document 1, a toner provided with a shell layer having an oxazoline group is described in order to improve the charge retention of the toner. The shell layer having an oxazoline group can provide a toner excellent in charge retention, heat storage stability, and low-temperature fixability. In Patent Document 2, a toner containing a diester compound as a softening agent is described. By using the diester compound, a toner excellent in low-temperature fixability, hot offset resistance, and heat storage stability can be provided.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The toner of Patent Document 1 has excellent heat-resistant storage stability and has an effect of preventing toner aggregation. However, it has been found that when a large number of images printed by a printer are stacked after the toner is stored in a high-temperature and high-humidity environment for a long time, there may occur a problem (back contamination) in which the toner adheres to the back surface of the paper. The toner of Patent Document 2 has excellent low-temperature fixing property and heat-resistant storage stability and has an effect of preventing toner aggregation. However, it has been found that when the toner is stored in a high-temperature and high-humidity environment for a long time, back contamination and electrostatic offset may occur. For the above reasons, the present disclosure provides a toner that is excellent in low-temperature fixing property, heat-resistant stability, and electrostatic offset resistance and has little occurrence of back contamination.

Means for Solving the Problems

[0005] The present disclosure relates to a toner having toner particles including core particles containing a binder resin and a wax, and a shell formed on the surface of the core particles, wherein the wax contains Wax A, the shell contains a resin having a functional group B, The wax A is a diester wax, the surface charge density DA of the Wax A is from -0.0080 to -0.0025, and the absolute difference (│DA - DB│) between the surface charge density DA of the Wax A and the surface charge density DB of the functional group B is 0.0025 or less. and, the functional group B is an oxazoline group, the resin having the functional group B is a vinyl resin, the vinyl resin has a structure represented by the following formula (2B) It relates to such a toner. TIFF0007710912000001.tif44170 (In formula (2B), R 4 represents a hydrogen atom or an alkyl group.)

Advantages of the Invention

[0006] According to the present disclosure, it is possible to provide a toner that is excellent in low-temperature fixing property, heat-resistant stability, and electrostatic offset resistance and has little occurrence of back contamination.

Best Mode for Carrying Out the Invention

[0007] The description of "XX or more and YY or less" or "XX to YY" representing a numerical range means a numerical range including the lower limit and the upper limit which are the endpoints, unless otherwise specified. When the numerical ranges are described stepwise, the upper limit and the lower limit of each numerical range can be arbitrarily combined. When the numerical ranges are described stepwise, the upper limit and the lower limit of each numerical range can be arbitrarily combined.

[0008] To improve the fixability of the toner, the type and amount of wax have a great influence, and the present inventors also focused on the type of wax and conducted studies. Among them, in particular, from the viewpoint of fixability, an ester wax having a polar group was excellent. The ester wax oozes out onto the surface of the toner particles during fixing, promoting the melting of the surface of the toner particles and enabling low-temperature fixing. However, in the toner stored in a high-temperature and high-humidity environment for a long time, the wax oozes out onto the surface of the toner particles, making it difficult to suppress electrostatic offset and back contamination.

[0009] Electrostatic offset occurs when the toner on the paper randomly flies electrostatically onto the fixing member at a stage before the paper with unfixed toner enters the nip between the fixing member and the pressure roller. Regarding the mechanism of electrostatic offset generation, first, the wax oozes out onto the surface of the toner particles due to long-term storage in a high-temperature and high-humidity environment, and the waxes aggregate and crystallize to form large domains. As a result, the composition on the surface of the toner particles becomes non-uniform, and the charge distribution of the toner broadens, so it is considered that electrostatic offset occurs.

[0010] On the other hand, back contamination is caused by the low adhesion between the fixed paper and the toner, and the toner adheres to the back surface of the stacked paper. Multiple mechanisms for back contamination are conceivable. It is conceivable that the surface melting of the toner particles is insufficient and unfixed toner adheres to the back surface of the paper, or that the toner that has been sufficiently melted and has a reduced viscosity adheres to the back surface of the paper. In addition, when the surface melting of toner particles is insufficient, the cause may be that the wax does not sufficiently penetrate the surface of the toner particles during fixing. Also, when stored in a high-temperature and high-humidity environment for a long time, the wax penetrates the surface of the toner particles, and the surface composition of the toner particles becomes non-uniform, resulting in broadening of the charge distribution of the toner and unevenness of the toner loading amount during development.

[0011] Therefore, the inventors considered that if the chargeability of the toner does not change even when the wax penetrates the surface of the toner particles, it may be possible to suppress low-temperature fixability, electrostatic offset, and the occurrence of background staining. As a result of intensive studies by the inventors, in toner particles having core particles containing wax and a shell formed on the surface of the core particles, by adjusting the ease of penetration of the wax into the surface of the toner particles, if the affinity between the wax and the shell is high, it was found that the problems of electrostatic offset and background staining can be solved.

[0012] As a result of further studies, in order to adjust the ease of penetration of the wax into the surface of the toner particles, the surface charge density of the wax is adjusted to a certain range, and in order to increase the affinity between the wax and the shell, by reducing the absolute difference in the surface charge density of the functional groups contained in the wax and the shell, it was found that the problems of electrostatic offset and background staining can be solved.

[0013] That is, the present disclosure is a toner having core particles containing a binder resin and wax, and toner particles having a shell formed on the surface of the core particles, wherein the wax contains wax A, the shell contains a resin having a functional group B, The wax A is a diester wax, the surface charge density DA of the wax A is -0.0080 to -0.0025, the absolute difference (│DA - DB│) between the surface charge density DA of the wax A and the surface charge density DB of the functional group B is 0.0025 or less and, the functional group B is an oxazoline group, the resin having the functional group B is a vinyl resin, the vinyl resin has a structure represented by the following formula (2B) relates to the toner. TIFF0007710912000002.tif44170 (In formula (2B), R 4 represents a hydrogen atom or an alkyl group.)

[0014] Here, the surface charge densities DA and DB (dimensionless quantities) are obtained by calculating the topological polar surface area (tPSA) and the partial charge according to the following paper and calculating the partial charge per unit topological polar surface area. "Iterative partial equalization of orbital electronegativity - a rapid access to atomic charges" Tetrahedron 1980, 36, 3219. Specifically, the topological polar surface area (tPSA) and the partial charge can be calculated by Advanced Chemistry Development (ACD / Labs) Software V11.02 (c1994 - 2016 ACD / Labs).

[0015] When the surface charge density of the wax and the absolute difference between the surface charge density of the wax and the surface charge density of the functional groups contained in the shell satisfy the above range, the wax oozes out moderately onto the toner particle surface. Furthermore, since the oozed wax has a high affinity with the shell, it does not form a large wax domain and maintains the composition near the toner particle surface uniformly. As a result, the broadening of the charge distribution of the toner does not occur, the deviation of the toner loading amount is significantly reduced, and the occurrence of background contamination can be sufficiently suppressed.

[0016] When the surface charge density DA of wax A exceeds -0.0025, the wax does not ooze out sufficiently even during fixing, and the surface melting of the toner particles is not promoted. Therefore, the fixing property is greatly reduced, and the effect of suppressing background contamination cannot be obtained. When the surface charge density DA of Wax A is less than -0.0080, for the toner stored in a high-temperature and high-humidity environment for a long time, due to a large amount of bleeding of the wax, the charge distribution of the toner broadens, resulting in electrostatic offset from the initial stage of printing and no effect of suppressing back staining can be obtained. The surface charge density DA is preferably -0.0050 to -0.0030, more preferably -0.0040 to -0.0030.

[0017] The absolute difference (│DA - DB│) between the surface charge density DA of Wax A and the surface charge density DB of the functional group B is 0.0025 or less. When the absolute difference (│DA - DB│) exceeds 0.0025, the wax that has bled out on the toner particle surface forms domains, and the composition on the toner particle surface becomes non-uniform, resulting in broadening of the toner charge distribution. As a result, electrostatic offset occurs after the toner deteriorates during durability, and no effect of suppressing back staining can be obtained. The absolute difference (│DA - DB│) is preferably 0.0020 or less, more preferably 0.0015 or less. On the other hand, the lower limit is not particularly limited, but is preferably 0.0000 or more, more preferably 0.0005 or more.

[0018] The shell used for the toner is not particularly limited as long as it is a resin containing the functional group B that satisfies the above surface charge density. The surface charge density DB of the functional group B is preferably -0.0050 to -0.0015, more preferably -0.0030 to -0.0020. The functional group B is preferably an oxazoline group. In this case, it becomes easier for the core particles and the shell of the toner to crosslink, and the durability of the shell is greatly improved, so that charge broadening is suppressed over a long period, and electrostatic offset can be further improved.

[0019] As the resin containing the functional group B (preferably an oxazoline group), a vinyl resin is preferred. Preferred examples of the vinyl resin include polymers or copolymers of monomers containing the vinyl compound represented by the formula (2). That is, the vinyl resin preferably has a structure represented by the following formula (2B).

[0020] [Chem.]

[0021] In formula (2) or (2B), R 4 represents a hydrogen atom or an alkyl group. Examples of the alkyl group represented by R 4 are preferably alkyl groups having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, or an isopropyl group. R 4 is more preferably a hydrogen atom. Preferable examples of the vinyl compound represented by formula (2) include 2-vinyl-2-oxazoline.

[0022] More preferable examples of the vinyl resin include copolymers of the vinyl compound represented by formula (2) and vinyl compounds other than the vinyl compound represented by formula (2). Examples of vinyl compounds other than the vinyl compound represented by formula (2) include ethylene, propylene, butadiene, vinyl chloride, (meth)acrylic acid, (meth)acrylic acid esters, acrylonitrile, and styrene. (Meth)acrylic acid esters are preferably (meth)acrylic acid alkyl esters, and preferably have 1 to 4 carbon atoms in the alkyl group. (Meth)acrylic acid alkyl esters are preferably methyl (meth)acrylate or ethyl (meth)acrylate, more preferably methyl methacrylate. The vinyl resin is preferably a copolymer of the vinyl compound represented by formula (2) and (meth)acrylic acid alkyl ester. More preferably, it is a copolymer of the vinyl compound represented by formula (2) and methyl methacrylate. The content ratio of the structure represented by formula (2B) in the vinyl resin is preferably 5% to 98% by mass, more preferably 20% to 95% by mass.

[0023] In order to form a shell using a resin containing an oxazoline group as a functional group, for example, an aqueous solution of a polymer containing an oxazoline group (such as "Epocros (registered trademark) WS series" manufactured by Nippon Shokubai Co., Ltd.) can be used. "Epocros WS-300" and "Epocros WS-700" each contain a copolymer of 2-vinyl-2-oxazoline and an alkyl methacrylate. The functional groups contained in the shell are measured using surface analysis such as TOF-SIMS and devices such as pyrolysis GC / MS.

[0024] The wax contains wax A. In addition to wax A, the toner particles may contain other known waxes to such an extent that the above effects are not inhibited. Wax A is not particularly limited as long as the surface charge density DA is -0.0080 to -0.0025, but preferably contains a diester wax, and is preferably a diester wax. Examples of the diester wax include esters of dicarboxylic acids and monoalcohols and esters of diols and monocarboxylic acids. Examples of the diol include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol. Examples of the dicarboxylic acid include adipic acid, pimelic acid, suberic acid, azelaic acid, decanedioic acid, undecanedioic acid, and dodecanedioic acid. Here, linear fatty acids and linear alcohols are exemplified, but they may have a branched structure.

[0025] As the monoalcohol to be condensed with the above dicarboxylic acid, an aliphatic monoalcohol is preferable. Specifically, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, octacosanol, etc. can be mentioned. Among them, docosanol is preferable from the viewpoints of fixability and developability.

[0026] As the monocarboxylic acid to be condensed with the above diol, an aliphatic monocarboxylic acid is preferred. Specifically, examples of fatty acids include lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, and cerotic acid. Among them, stearic acid and behenic acid are preferred from the viewpoints of fixing property and developability. The diester wax is preferably a compound represented by the following formula (1).

[0027]

Chemical formula

[0028] In the above formula (1), R 1 represents an alkylene group having 2 to 12 carbon atoms (preferably 2 to 8 carbon atoms, more preferably 2 to 4 carbon atoms). R 2 and R 3 represent linear alkyl groups having 15 to 25 carbon atoms (preferably 16 to 22 carbon atoms, more preferably 16 to 20 carbon atoms), and R 2 and R 3 are independent of each other. Examples of the diol that supplies the partial structure represented by formula (1) include ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol. Among them, ethylene glycol and 1,9-nonanediol are preferred. Among them, ethylene glycol in which R 1 is an alkylene group having 2 carbon atoms, that is, an ethylene group, is more preferred from the viewpoints of compatibility with the binder resin and ease of bleeding during heat fixing.

[0029] As the monocarboxylic acid to be condensed with the above diol, an aliphatic monocarboxylic acid is preferred. Specifically, examples of fatty acids include lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, and cerotic acid. Among them, stearic acid and behenic acid are preferred from the viewpoints of fixing property and developability.

[0030] The content of wax (preferably wax A) is preferably 2 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably, it is 4 parts by mass or more and 25 parts by mass or less, still more preferably 5 parts by mass or more and 20 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less. The melting point of the wax is preferably 60°C or higher and 90°C or lower, and more preferably 65°C or higher and 80°C or lower. When this range is satisfied, there is a tendency to easily suppress back contamination. Paraffin wax may be used as the wax.

[0031] Specific production examples of the diester wax represented by the following formula (1) are shown below. First, an alcohol and a carboxylic acid as raw materials are added to a reaction vessel. The molar ratio of the alcohol and the carboxylic acid is appropriately adjusted according to the chemical structure of the desired wax. In consideration of the reactivity in the dehydration condensation reaction, etc., either the alcohol or the carboxylic acid may be added slightly in excess of the above ratio. Next, the mixture is appropriately heated to carry out a dehydration condensation reaction. To the esterification crude product obtained by the dehydration condensation reaction, a basic aqueous solution and an organic solvent are appropriately added to deprotonate the unreacted alcohol and carboxylic acid and separate them into the aqueous phase. After that, the desired diester wax can be obtained by appropriately performing washing with water, solvent evaporation, and filtration.

[0032] The binder resin that can be used in the toner is not particularly limited, and known resins for toner can be used. Specifically, examples include vinyl resins, styrene resins, styrene copolymer resins, polyester resins, polyol resins, polyvinyl chloride resins, phenol resins, natural resin-modified phenol resins, natural resin-modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, petroleum resins, and the like. Preferably, examples include styrene copolymer resins, polyester resins, hybrid resins in which a polyester resin and a vinyl resin are mixed or partially reacted with each other, and the like. Among these, from the viewpoint of compatibility with wax, a polyester resin or a vinyl resin is preferable, and a polyester resin is more preferable.

[0033] The binder resin preferably contains a polyester resin, and from the viewpoint of low-temperature fixability, it is preferable that the polyester resin is the main component. The main component means that its content is 50% by mass to 100% by mass (preferably 80% by mass to 100% by mass). It is more preferable that the binder resin is a polyester resin.

[0034] As the monomers used for the polyester resin, a polyhydric alcohol (a dihydric or trihydric or higher alcohol), a polyvalent carboxylic acid (a dihydric or trihydric or higher carboxylic acid), its acid anhydride or its lower alkyl ester are used. As the polyhydric alcohol monomer used for the polyester unit of the polyester resin, the following polyhydric alcohol monomers can be used. As the dihydric alcohol component, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and bisphenol represented by the formula (A) and its derivatives;

[0035] [Chemical formula]

[0036] (In the formula, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 or more and 10 or less.) Examples of the diols represented by formula (B) include.

[0037] [Chemical formula]

[0038] Examples of the alcohol component having a valence of 3 or more include sorbitol, 1,2,3,6 - hexanetetrol, 1,4 - sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4 - butanetriol, 1,2,5 - pentanetriol, glycerol, 2 - methylpropanetriol, 2 - methyl - 1,2,4 - butanetriol, trimethylolethane, trimethylolpropane, 1,3,5 - trihydroxymethylbenzene. Among these, preferably glycerol, trimethylolpropane, and pentaerythritol are used. These divalent alcohols and alcohols having a valence of 3 or more can be used alone or in combination of two or more.

[0039] As the polyvalent carboxylic acid monomer used in the polyester unit of the polyester resin, the following polyvalent carboxylic acid monomers can be used. Examples of the divalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid, isooctyl succinic acid, anhydrides of these acids, and lower alkyl esters of these acids. Among these, maleic acid, fumaric acid, terephthalic acid, and n-dodecenyl succinic acid are preferably used. Examples of the trivalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, Empol trimer acid, acid anhydrides of these acids, or lower alkyl esters of these acids. Among these, 1,2,4-benzenetricarboxylic acid, that is, trimellitic acid or its derivative is particularly preferably used because it is inexpensive and the reaction control is easy. These divalent carboxylic acids and trivalent or higher carboxylic acids can be used alone or in combination of two or more.

[0040] The method for producing the polyester resin is not particularly limited, and known methods can be used. For example, the aforementioned alcohol monomer and carboxylic acid monomer are charged simultaneously, and polymerized through an esterification reaction or transesterification reaction, and a condensation reaction to produce a polyester resin. Further, the polymerization temperature is not particularly limited, but a range of 180°C or higher and 290°C or lower is preferable. When polymerizing the polyester resin, for example, polymerization catalysts such as titanium-based catalysts, tin-based catalysts, zinc acetate, antimony trioxide, and germanium dioxide can be used. In particular, as the binder resin, a polyester resin polymerized using a tin-based catalyst is more preferable.

[0041] For the toner, various known colorants can be used. In the case of a black toner, using a magnetic material is preferable because the influence on the behavior of the wax is small and the above effects are easily achieved.

[0042] Hereinafter, an example of the method for producing the toner will be described. For the production of the core particles of the toner, various methods such as a pulverization method, a suspension polymerization method, and an aggregation method can be used. From the viewpoints of simplicity and material selectivity, the pulverization method is preferable. Hereinafter, an example of the pulverization method will be described. First, a binder resin, a wax, and additives such as a colorant and a charge control agent as necessary are mixed using a stirring device such as a Henschel mixer. Subsequently, the obtained mixture is melt-kneaded, then coarsely pulverized and pulverized, and the obtained pulverized product is classified. Thereby, toner core particles having a desired particle diameter are obtained.

[0043] Next, a shell is formed on the surface of the obtained toner core particles. The shell is formed, for example, by dispersing a material for forming the shell in an aqueous medium and adsorbing it on the surface of the toner core particles. The material of the shell may be dissolved in the aqueous medium. Further, a polar medium (for example, an alcohol such as methanol or ethanol) may be mixed in the aqueous medium. The shell does not necessarily need to cover the entire surface of the core particles, and there may be a portion where the core particles are exposed.

[0044] By going through the above-described steps, a dispersion of toner particles is obtained. Thereafter, if necessary, toner particles are obtained through filtration, a drying step, and a classification step. Further, if necessary, a mixer (for example, an FM mixer manufactured by Nippon Coke & Engineering Co., Ltd.) may be used to mix the toner particles and an external additive so that the external additive adheres to the surface of the toner particles. Note that the content and order of the above toner manufacturing method can be arbitrarily changed according to the required toner composition, characteristics, etc.

[0045] Next, the measurement methods for each physical property will be described. <Measurement Method for Melting Point of Wax> Weigh 5 mg of wax sample into a sample holder and perform measurement using DSC Q2000 (manufactured by TA Instruments) under the following conditions. Measurement start temperature: 20°C Measurement end temperature: 180°C Temperature rising rate: 10°C / min In the obtained DSC curve, take the peak top as the melting point.

[0046] <Volume Average Particle Diameter Dv of Toner Particles> The volume average particle diameter Dv, number average particle diameter Dn, and particle size distribution Dv / Dn of the toner particles are measured by a particle size measuring instrument (manufactured by Beckman Coulter, trade name: Multisizer). The measurement by this Multisizer is performed under the conditions of aperture diameter: 100 μm, dispersion medium: Isoton II (trade name), concentration 10%, and number of measured particles: 100,000. Specifically, take 0.2 g of toner particle sample into a beaker, add an aqueous solution of alkylbenzene sulfonic acid (manufactured by Fujifilm, trade name: Drywell) as a dispersant thereto. Then, further add 2 mL of the dispersion medium, wet the toner particles, and then add 10 mL of the dispersion medium. After dispersing with an ultrasonic disperser for 1 minute, perform measurement with the above particle size measuring instrument.

[0047] <Structure Analysis of Shell in Toner> The identification of the functional groups of the shell in the toner is performed using a time-of-flight secondary ion mass spectrometer (TOF-SIMS). The following apparatus is used under the following conditions to identify the partial structure from the fragment peaks of the toner shell. · Measuring apparatus: TRIFT-IV (trade name, manufactured by ULVAC-PHI, Inc.) · Primary ion: Au 3+ · Raster size: 100 μm × 100 μm · Neutralizing electron gun: Used

[0048] <Composition analysis of wax> The composition analysis of the wax in the toner particles can be performed using a nuclear magnetic resonance apparatus ( 1 1H-NMR, 13 13C-NMR). The apparatus used is described below. Each sample may be collected by separating it from the toner and then analyzed. Nuclear magnetic resonance apparatus ( 1 1H-NMR, 13 13C-NMR) Measuring apparatus: FT NMR apparatus JNM-EX400 (manufactured by JEOL Ltd.) Measuring frequency: 400 MHz Pulse condition: 5.0 μs Frequency range: 10500 Hz Number of integrations: 64 times

Example

[0049] Hereinafter, the present invention will be described in more detail using examples and comparative examples. The present invention is not limited in any way by the following examples. In the description of the following examples, "parts" means parts by mass unless otherwise specified.

[0050] The waxes used in the examples are shown in Table 1.

[0051]

Table 1

[0052] <Production example of toner 1> (Production of Polyester Resin 1) The following materials were mixed in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen inlet pipe. · 58.0 parts of polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane · 8.0 parts of ethylene glycol · 31.0 parts of terephthalic acid · 3.0 parts of trimellitic anhydride · 0.3 part of dibutyltin oxide After replacing the system with nitrogen by a vacuum operation, it was heated to 210 °C and reacted for 5 hours while introducing nitrogen to remove the generated water. Then, while continuing stirring, the temperature was gradually raised to 230 °C under reduced pressure and reacted for another 3 hours to synthesize Polyester Resin 1. The weight average molecular weight Mw was 9,500 and the Tg was 68 °C.

[0053] (Production of Magnetic Material) Fe 2+ 92.0 parts of an aqueous solution of ferrous sulfate with a concentration of 1.79 mol / L and 88.0 parts of an aqueous solution of sodium hydroxide with a concentration of 3.74 mol / L were added and mixed with stirring. The pH of this solution was 6.5. While maintaining this solution at a temperature of 89 °C and a pH of 9 - 12, air was blown in at 20 L / min to cause an oxidation reaction to produce core particles. When the ferrous hydroxide was completely consumed, the blowing of air was stopped and the oxidation reaction was terminated. The resulting magnetic core particles composed of magnetite had an octahedral shape. The shape of the magnetic material was octahedral and the number average particle size (D1) was 120 nm.

[0054] (Production of Toner Core Particles 1) The following materials were thoroughly mixed with an FM mixer (manufactured by Nippon Coke Industry Co., Ltd.) and then melt-kneaded with a twin-screw kneader (manufactured by Ikegai Iron Works Co., Ltd.). · Polyester Resin 1: 100.0 parts · "Acrybase (registered trademark) FCA-201-PS" manufactured by Fujikura Kasei Co., Ltd.: 3.0 parts · HNP9 (melting point: 76 °C, manufactured by Nippon Seiro Co., Ltd.): 5.0 parts · Wax 1: 15.0 parts · Magnetic material: 100.0 parts The obtained kneaded product was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product. Next, the obtained coarsely pulverized product was finely pulverized to about 5 μm using a turbo mill manufactured by Turbo Kogyo Co., Ltd., and then the fine and coarse powder was cut using a multi-stage classifier utilizing the Coandă effect to obtain toner core particles 1. The weight average particle diameter (D4) of the toner core particles 1 was 6.8 μm, and the Tg was 58°C.

[0055] (Production of toner particle dispersion liquid 1) After maintaining a reaction vessel containing 300.0 parts of ion-exchanged water at 30°C, 50.0 parts of an oxazoline group-containing polymer aqueous solution ("Epocros (registered trademark) WS-300" manufactured by Nippon Shokubai Co., Ltd., monomer mass ratio: methyl methacrylate / 2-vinyl-2-oxazoline = 1 / 9, solid content concentration: 10 mass%) was placed in the reaction vessel. After thoroughly stirring the contents of the reaction vessel, 300.0 parts of toner core particles 1 were added and stirred at a rotation speed of 200 rpm for 1 hour. Thereafter, 300.0 parts of ion-exchanged water were added. Subsequently, 6.0 parts of a 1 mass% aqueous ammonia solution was added to the reaction vessel, and while stirring at a rotation speed of 150 rpm, the temperature inside the reaction vessel was raised to 60°C at a rate of 0.5°C / min. After the temperature inside the reaction vessel reached 60°C, the contents of the reaction vessel were stirred at a rotation speed of 100 rpm and held at 60°C for 1 hour. When 1 hour had elapsed since the temperature inside the reaction vessel reached 60°C, 10.0 parts of a 1 mass% acetic acid aqueous solution were added to the reaction vessel. Subsequently, while stirring the contents of the reaction vessel at a rotation speed of 100 rpm, it was held at 60°C for 30 minutes. Subsequently, a 1 mass% aqueous ammonia solution was added to the reaction vessel to adjust the pH inside the reaction vessel to 7. Subsequently, the contents of the reaction vessel were cooled until the temperature became normal temperature (about 25°C) to obtain toner particle dispersion liquid 1.

[0056] (Extraction of toner particles 1) After filtering the toner particle dispersion liquid 1, it was dispersed again in ion-exchanged water. Dispersion and washing were repeated until the electrical conductivity of the ion-exchanged water sufficiently decreased. After obtaining wet cake-like toner particles, they were crushed and placed in a constant temperature bath at 40 °C for 70 h and sufficiently dried to obtain toner particles 1 as a powder.

[0057] (Manufacture of Toner 1) Using an FM mixer (「FM-10B」manufactured by Nippon Coke & Engineering Co., Ltd.), under the condition of a rotation speed of 3500 rpm, 100.0 parts of toner particles and 1.0 part of hydrophobic silica particles (using 3-aminopropyltriethoxysilane and dimethyl silicone oil as hydrophobizing agents) were mixed for 5 minutes. Thereafter, coarse particles were removed using a 300-mesh (aperture 48 μm) sieve to obtain Toner 1. The formulation and the obtained physical properties are shown in Table 2.

[0058] <Manufacturing Examples of Toner 2 to 10>[ In the manufacturing example of Toner 1, Toners 2 to 10 were obtained in the same manner except that the wax type and amount were changed as shown in Table 2. The formulation and the obtained physical properties are shown in Table 2.

[0059] <Manufacturing Example of Toner 11>[ In the manufacturing example of Toner 1, the wax type and amount were changed as shown in Table 2. Instead of adding 50.0 parts of 「Epocros (registered trademark) WS-300」in the manufacture of the toner particle dispersion liquid 1, 20.0 parts of 「Epocros (registered trademark) WS-700 (monomer mass ratio: methyl methacrylate / 2-vinyl-2-oxazoline / butyl acrylate = 4 / 5 / 1, solid content concentration: 25 mass%)」were added. Toner 11 was obtained in the same manner as above. The formulation and the obtained physical properties are shown in Table 2.

[0060] <Manufacturing Example of Toner 12>[ In the manufacturing example of Toner 1, the wax type and amount were changed as shown in Table 2, and Toner 12 was obtained in the same manner except that the polyester resin 1 was changed to a styrene acrylic resin manufactured by the following manufacturing method. The formulation and the obtained physical properties are shown in Table 2.

[0061] (Production of Styrene-Acrylic Resin) In a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen inlet pipe, the following materials were mixed and heated with stirring while maintaining the temperature at 180 °C. · Styrene 78.0 parts · n-Butyl acrylate 20.0 parts · Acrylic acid 2.0 parts · Xylene 300.0 parts Subsequently, 50.0 parts of a xylene solution of 2.0 mass% t-butyl hydroperoxide was continuously added dropwise to the system over 4.5 hours. After cooling, the solvent was separated and removed to synthesize a styrene-acrylic resin. The weight average molecular weight Mw was 14,500 and the Tg was 65 °C.

[0062] <Production Example of Toner 13> In the production of Toner 12, Toner 13 was obtained in the same manner except that the wax type and amount were changed as shown in Table 2. The formulation and the obtained physical properties are shown in Table 2.

[0063] <Production Example of Toner 14> In the production of Toner Particle Dispersion 1 of Toner 1, Toner 14 was obtained in the same manner except that pH adjustment was not performed and Resin Fine Particle Dispersion 1 below was used instead of the aqueous solution of the oxazoline group-containing polymer. In addition, 10.0 parts of the resin fine particle dispersion was added. The formulation and the obtained physical properties are shown in Table 2.

[0064] (Production of Resin Fine Particle Dispersion 1) 30 parts of acetone was placed in a reaction vessel equipped with a cooling pipe, a stirrer, a thermometer, and a nitrogen inlet pipe, and stirred. · 2-Acrylamido-phenylsulfonic acid methyl ester 15.0 parts · Styrene 68.8 parts · n-Butyl acrylate 15.0 parts · Acrylic acid 1.2 parts The above materials were charged into the reaction vessel and dissolved. The temperature was raised so that the inside of the reaction vessel reached 60 °C. Subsequently, 2.0 parts of 2,2-azobis(2,4-dimethylvaleronitrile) was added as a polymerization initiator and reacted for 8 hours. After cooling the reaction solution, it was concentrated and dried by an evaporator, and further dried in a vacuum dryer at 40 °C for 10 hours to obtain a resin. The obtained resin was dissolved in acetone again and prepared to have a solid content ratio of 75% by mass. Then, it was added dropwise with stirring into 100.0 parts of ion-exchanged water, emulsified, and further acetone was distilled off under a reduced pressure of 100 mmHg in the reaction vessel. It was diluted to a solid content ratio of 15% by mass to obtain Resin Fine Particle Dispersion Liquid 1.

[0065] <Production Example of Toner 15> In the production of Toner Particle Dispersion Liquid 1 of Toner 1, Toner 15 was obtained in the same manner except that pH adjustment was not performed and Resin Fine Particle Dispersion Liquid 2 below was used instead of the aqueous solution of the oxazoline group-containing polymer. Incidentally, 10.0 parts of the resin fine particle dispersion liquid was added. The formulation and the obtained physical properties are shown in Table 2.

[0066] (Production of Resin Fine Particle Dispersion Liquid 2) 5.0 parts of sodium dodecyl sulfate and 1000.0 parts of ion-exchanged water were put into a beaker equipped with a stirrer, and stirring was continued until completely dissolved at 25 °C to prepare an aqueous solution. Next, the following materials were mixed to prepare a polymerizable monomer composition. · Styrene 70.0 parts · Butyl acrylate 13.0 parts · 2-Ethylhexyl acrylate 12.0 parts · Methyl methacrylate (MMA) 5.0 parts After the above polymerizable monomer composition was cooled to 15 °C, 6.0 parts of tertiary butyl peroxypivalate was mixed as a polymerization initiator and added to the above aqueous solution. Then, an emulsion of the above polymerizable monomer composition was prepared by irradiating ultrasonic waves with a high-power ultrasonic homogenizer (VCX-750) for 13 minutes (1-second interval, maintained at 25 °C). The emulsion was poured into a heated and dried reaction vessel, and nitrogen was bubbled for 30 minutes while stirring the emulsion at 200 rpm. Then, stirring was carried out at 70 °C for 6 hours. Thereafter, the emulsion was allowed to air-cool while being stirred to stop the reaction, and a resin fine particle dispersion liquid 2 of a styrene-acrylic resin serving as the outermost layer material was obtained.

[0067] <Production Examples of Toners 16 to 18> In the production example of Toner 1, except that the type and amount of wax were changed as shown in Table 2, the same procedure was carried out to obtain Toners 16 to 18. The formulations and the obtained physical properties are shown in Table 2.

[0068] <Evaluation of Low-Temperature Fixing Property> The evaluation of the low-temperature fixing property was carried out using an LBP7600C modified so that the fixing temperature could be adjusted, at a process speed of 300 mm / sec, in a normal temperature and humidity environment (temperature 23 °C, humidity 50%), while changing the fixing temperature in 5 °C increments from 140 °C. Using the toner to be evaluated, a solid image with a toner loading of 0.40 mg / cm 2 was formed on LETTER size Business 4200 paper (manufactured by XEROX, 75 g / m 2 ), and the image was heated and pressed without oil to form a fixed image. Using a Kimwipe (S-200, manufactured by Cresia Co., Ltd.), a load of 75 g / cm 2 was applied to rub the fixed image 10 times. The temperature at which the image density reduction rate before and after rubbing was less than 10% was defined as the fixing temperature, and the evaluation was carried out based on the following criteria. For the measurement of the image density, a color reflection densitometer X-RITE 404A (manufactured by X-Rite Co.) was used to measure the relative density with respect to the printed-out image of the white background part with a manuscript density of 0.00, and the reduction rate of the image density after rubbing was calculated. The evaluation results are shown in Table 3. A to C were judged to be good. A: Less than 150 °C B: 150 °C or more and less than 160 °C C: 160 °C or more and less than 170 °C D: 170 °C or more and less than 180 °C E: 180 °C or more

[0069] <Evaluation of Electrostatic Offset> The evaluation of the initial and post-durability electrostatic offset was performed using the HL-5470DW (manufactured by Brother Industries, Ltd.) under normal temperature and humidity environment (temperature: 23°C, humidity: 50%). A toner cartridge left in a high temperature and high humidity environment (temperature: 40°C, humidity: 95%) for 30 days was used. For the initial evaluation, a halftone chart image of an isolated single dot was output, and the electrostatic offset generated at the rear end of the image was judged according to the following criteria. A to C were judged as good. A: No occurrence. B: A level that can be slightly confirmed visually. C: Can be confirmed visually but at a minor level. D: The occurrence can be clearly confirmed. E: Occurring across the entire image area. For the post-durability evaluation, a horizontal line with a printing rate of 1% was output as a durability image. After printing 2000 sheets with 2-sheet intermittent continuous paper, a halftone chart image of an isolated single dot was output in the same way as the initial evaluation, and the electrostatic offset generated at the rear end of the image was judged according to the above criteria.

[0070] <Evaluation of backside contamination> The evaluation of backside contamination was performed using the HL-5470DW (manufactured by Brother Industries, Ltd.) under normal temperature and humidity environment (temperature: 23°C, humidity: 50%). Using a toner cartridge left in a high temperature and high humidity environment (temperature: 40°C, humidity: 95%) for 30 days, 100 full-solid images were output to the output tray, and the image density of the back surface of the paper output as the second sheet (the part in contact with the first full-solid image) was evaluated. The image density was measured using a Macbeth densitometer (manufactured by Macbeth) as a reflection densitometer with an SPI filter. A to C were judged as good. A: The density of backside contamination is less than 0.02 B: The density of backside contamination is 0.02 or more and less than 0.05 C: The density of backside contamination is 0.05 or more and less than 0.10 D: The density of backside contamination is 0.10 or more

[0071]

Table 2

[0072]

Table 3

Claims

1. A toner comprising core particles containing a binder resin and a wax, and toner particles having a shell formed on the surface of the core particles, wherein the wax contains Wax A, the shell contains a resin having a functional group B, the Wax A is a diester wax, the surface charge density DA of the Wax A is from -0.0080 to -0.0025, the absolute difference │DA - DB│ between the surface charge density DA of the Wax A and the surface charge density DB of the functional group B is 0.0025 or less, the functional group B is an oxazoline group, the resin having the functional group B is a vinyl resin, and the vinyl resin has a structure represented by the following formula (2B), characterized toner. (In formula (2B), R4 represents a hydrogen atom or an alkyl group.)

2. The toner according to claim 1, wherein the content ratio of the structure represented by the formula (2B) in the vinyl resin is from 20% by mass to 95% by mass.

3. The toner according to claim 1 or 2, wherein the Wax A is a compound represented by the following formula (1). In the above formula (1), R １ represents an alkylene group having 2 to 12 carbon atoms, R ２ and R ３ represent linear alkyl groups having 15 to 25 carbon atoms, and R ２ and R ３ are independent of each other.

4. Said R １ The toner according to claim 3, wherein R is an alkylene group having 2 carbon atoms.

5. The toner according to any one of claims 1 to 4, wherein the content of the Wax A is 2 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.

6. The toner according to any one of claims 1 to 5, wherein the binder resin contains a polyester resin.

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