Toner

Abstract

To provide toner capable of controlling a seizure on a development roller while achieving both fixability and heat-resistant storage stability in low temperature fixing toner.SOLUTION: In toner including toner particles including a binder resin, the toner particles include a styrene resin dispersed in the binder resin, hydrocarbon wax dispersed in the styrene resin and ester wax used as an included accelerator. The average dispersion diameter of the styrene resin is 200 nm or more and 900 nm or less; the average dispersion diameter of the hydrocarbon wax is smaller than that of the styrene resin and is 50 nm or more and 300 nm or less; and the inclusion rate being the volume ratio of the hydrocarbon wax occupied in the distributed particles of the styrene resin is 20% or more and 50% or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to toner. [Background technology]

[0002] In recent years, toners are required to have low-temperature fixing properties in order to realize energy saving in image forming devices using electrophotography, such as copying machines, multifunction machines, printers, facsimile machines, etc. Generally, toners are used that have external additives attached to the surfaces of toner particles (toner cores) that are mainly composed of resin.

[0003] Conventionally, a method of adding a low melting point wax to toner particles has been known as a method for improving the low temperature fixing property of a toner, and a method of adding a styrene resin to toner particles has been known as a method for imparting fluidity to a toner. In the following, a toner with improved low temperature fixing property is also referred to as a low temperature fixing toner.

[0004] For example, Patent Document 1 discloses toner particles containing two types of resins, one of which is a copolymer obtained by copolymerizing monomers containing a styrene-based monomer and an acrylic-based monomer, and which contains a wax as a release agent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-070076 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of toner in which a low melting point wax is added (internally added) to toner particles, if the dispersibility of the low melting point wax in the toner particles is poor, the low melting point wax may be unevenly distributed on the surface of the toner particles. Therefore, due to the low melting point wax exposed and present on the surface of the toner particles, there are problems such as deterioration of the heat-resistant storage property of the toner and occurrence of toner sticking to the developing roller.

[0007] The toner of the present disclosure has been found in view of such circumstances, and the main object of the present disclosure is to provide a toner that can achieve both fixability and heat-resistant storage property in a low-temperature fixing toner while suppressing sticking to the developing roller.

Means for Solving the Problems

[0008] The toner of the present disclosure made to solve the above problems is a toner having toner particles containing a binder resin, wherein the toner particles include a styrene resin dispersed in the binder resin, a hydrocarbon wax dispersed in the styrene resin, and an ester wax as an encapsulation promoter, the average dispersion diameter of the styrene resin is 200 nm or more and 900 nm or less, the average dispersion diameter of the hydrocarbon wax is smaller than the average dispersion diameter of the styrene resin and 50 nm or more and 300 nm or less, and the encapsulation ratio which is the volume ratio of the hydrocarbon wax in the dispersed particles of the styrene resin is 20% or more and 50% or less.

[0009] In the above toner, when the SP value of the styrene resin is SP1, the SP value of the hydrocarbon wax is SP2, and the SP value of the ester wax is SP3, it is preferable to satisfy the relationship of SP2 < SP3 < SP1.

[0010] In the above toner, it is preferable to satisfy the relationships of the following formulas (1) and (2). SP3 - SP2 ≤ 1.0 ···(1) SP1 - SP3 ≤ 1.0 ···(2)

[0011] In the above toner, when the melting point of the hydrocarbon wax is T1 and the melting point of the ester wax is T2, it is preferable to satisfy the relationship of T1 < T2.

[0012] In the above toner, the content of the ester wax in the toner particles is preferably 0.2% by mass or more and 1% by mass or less.

[0013] In the above toner, the content of the hydrocarbon wax in the toner particles is preferably 2 times or more and 5 times or less the content of the ester wax.

[0014] In the above toner, the content of the styrene resin in the toner particles is preferably 5 times or more and 10 times or less the content of the ester wax.

Advantages of the Invention

[0015] The toner of the present disclosure has excellent effects such as being able to achieve both fixability and heat-resistant storage stability in a low-temperature fixing toner and being able to suppress sticking to the developing roller.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic diagram for explaining the configuration of the toner according to an embodiment of the present disclosure. [Diagram 2] It is a schematic diagram for explaining the effect of attracting the styrene resin and the hydrocarbon wax among the mechanisms in which the ester wax functions as an encapsulation promoter. [Diagram 3] It is a schematic diagram for explaining the effect of enhancing the dispersibility of the hydrocarbon wax in the styrene resin among the mechanisms in which the ester wax functions as an encapsulation promoter.

Modes for Carrying Out the Invention

[0017] Hereinafter, the toner of the present disclosure will be described in detail.

[0018] 1. Toner Particles (Toner Core) The toner particles according to the present embodiment are composed of an internal additive such as a colorant and a binder resin, and the internal additive is dispersed in the binder resin. An external additive is attached to the surface of the toner particles. If necessary, any optional components may be contained within a range that does not impair the effects of the present disclosure. The average primary particle diameter of the toner particles can be appropriately selected according to the purpose, and may be, for example, 4.5 μm or more and 8 μm or less.

[0019] The method for producing the toner particles is not particularly limited, and for example, the toner particles can be produced by a pulverization method. The toner particles can be produced by a pulverization method, for example, by carrying out a mixing step of dry-mixing materials including an internal additive such as a colorant and a binder resin in a mixer, a melting and kneading step of melting and kneading the obtained mixture in a kneader, a pulverization step of cooling and solidifying the obtained molten kneaded product, pulverizing the solidified product in a pulverizer to obtain a finely pulverized product, and a classification step of adjusting the particle size of the obtained finely pulverized product using a classifier or the like as necessary.

[0020] Fig. 1 is a schematic diagram for explaining the configuration of a toner according to an embodiment of the present disclosure, and toner particles T shown on the right side of Fig. 1 represent the configuration of toner particles according to this embodiment. When only a styrene-based resin is added to toner particles containing a hydrocarbon-based wax as a release agent as shown on the left side of Fig. 1, as shown in the center of Fig. 1, some of the hydrocarbon-based wax is encapsulated in the styrene-based resin, but much of it is not encapsulated.

[0021] In contrast, the toner particles according to this embodiment contain a styrene resin dispersed in a binder resin, a hydrocarbon wax dispersed in the styrene resin, and an ester wax as an encapsulation promoter, as shown in toner particle T on the right side of Fig. 1. By containing the ester wax as an encapsulation promoter, the toner particles according to this embodiment contain a larger amount of the hydrocarbon wax in the dispersed particles of the styrene resin compared to the state shown in the center of Fig. 1, and the hydrocarbon wax is present in a more dispersed state.

[0022] By encapsulating the hydrocarbon wax in the styrene resin, the low-melting-point hydrocarbon wax is encapsulated in the styrene resin in the temperature range during storage of the toner, and therefore the heat-resistant storage stability of the toner can be improved. In addition, when the temperature reaches the fixable temperature range (non-offset range) of the toner, both the styrene resin and the hydrocarbon wax melt, so the encapsulation has the effect of making the fixability less likely to be hindered. Furthermore, the encapsulation makes it difficult for the hydrocarbon wax (low-melting-point wax) to be exposed and present on the surface of the toner particles, and therefore makes it possible to suppress the toner from burning onto the developing roller.

[0023] FIG. 2 is a schematic diagram illustrating the effect of bringing together a styrene-based resin and a hydrocarbon-based wax, which is one of the mechanisms by which ester wax functions as an encapsulation promoter. As shown in FIG. 2, ester wax with a low melting point is compatible with styrene-based resin, so that it brings together the styrene-based resin and the hydrocarbon-based wax. This allows the ester wax to function as an encapsulation promoter. Furthermore, FIG. 3 is a schematic diagram illustrating the effect of increasing the dispersibility of the hydrocarbon-based wax in the styrene-based resin, which is one of the mechanisms by which ester wax functions as an encapsulation promoter. As shown in FIG. 3, ester wax is also compatible with the hydrocarbon-based wax, so that it promotes the inclusion of the hydrocarbon-based wax in the dispersed particles of the styrene-based resin with a small dispersion diameter.

[0024] Due to the above mechanism, the toner according to this embodiment has a controlled particle diameter (dispersion diameter) of the dispersed particles of the styrene-based resin and a controlled dispersion diameter of the hydrocarbon-based wax (low melting point wax) encapsulated in the dispersed particles of the styrene-based resin, thereby making it possible to suppress burn-in to the developing roller while achieving both fixing properties and heat-resistant storage stability in a low-temperature fixing toner.

[0025] Specifically, in the toner according to the present embodiment, the average dispersion diameter of the styrene resin is 200 nm or more and 900 nm or less, the average dispersion diameter of the hydrocarbon wax is smaller than that of the styrene resin and is 50 nm or more and 300 nm or less, and the encapsulation rate, which is the volume ratio of the hydrocarbon wax in the dispersed particles of the styrene resin, is 20% or more and 50% or less. In this way, the hydrocarbon wax is encapsulated in the styrene resin and the average dispersion diameters of the styrene resin and the hydrocarbon wax are controlled, so that the low-temperature fixing toner can be both fixed and heat-resistant storage stability, while the seizure on the developing roller can be suppressed.

[0026] In the toner particles according to the present embodiment, the average dispersion diameter of the styrene resin dispersed in the binder resin is 200 nm or more and 900 nm or less, preferably 400 nm or more and 800 nm or less, and more preferably 500 nm or more and 700 nm or less. By having the average dispersion diameter of the styrene resin be equal to or more than the lower limit, the heat-resistant storage stability of the toner can be improved and the toner can be prevented from burning onto the developing roller. By having the average dispersion diameter of the styrene resin be equal to or less than the upper limit, the fixing property of the toner can be improved.

[0027] In the toner particles according to the present embodiment, the average dispersion diameter of the hydrocarbon wax dispersed in the styrene resin is 50 nm or more and 300 nm or less, preferably 70 nm or more and 200 nm or less, and more preferably 80 nm or more and 150 nm or less. By having the average dispersion diameter of the hydrocarbon wax be equal to or more than the lower limit, the fixing property of the toner can be further improved. By having the average dispersion diameter of the hydrocarbon wax be equal to or less than the upper limit, the heat-resistant storage stability of the toner can be further improved and the burning of the toner onto the developing roller can be further suppressed.

[0028] In the toner particles according to this embodiment, the inclusion ratio, which is the volume ratio of the hydrocarbon wax in the dispersed particles of the styrene resin, is 20% or more and 50% or less, and more preferably 25% or more and 40% or less. When the inclusion ratio is not less than the above lower limit, the heat-resistant storage stability of the toner can be further enhanced, and the adhesion of the toner to the developing roller can be further suppressed. When the inclusion ratio is not more than the above upper limit, the fixing property of the toner can be further enhanced.

[0029] In the toner particles according to this embodiment, assuming that the SP value of the styrene resin is SP1, the SP value of the hydrocarbon wax is SP2, and the SP value of the ester wax is SP3, it is preferable to satisfy the relationship of SP2 < SP3 < SP1. Thereby, the hydrocarbon wax is more likely to be encapsulated in the styrene resin, the heat-resistant storage stability of the toner can be further enhanced, and the adhesion of the toner to the developing roller can be further suppressed.

[0030] In the toner particles according to this embodiment, it is preferable to further satisfy the relationships of the following formulas (1) and (2). For the following formula (1), it is more preferable that SP3 - SP2 is 0.9 or less, and for the following formula (2), it is more preferable that SP1 - SP3 is 0.8 or less. Thereby, these materials are more compatible with each other, the heat-resistant storage stability of the toner can be further enhanced, and the adhesion of the toner to the developing roller can be further suppressed. SP3 - SP2 ≤ 1.0 ···(1) SP1 - SP3 ≤ 1.0 ···(2)

[0031] In the toner particles according to this embodiment, assuming that the melting point of the hydrocarbon wax is T1 and the melting point of the ester wax is T2, it is preferable to satisfy the relationship of T1 < T2, and more preferably T2 is 5°C or higher than T1. Thereby, the dispersibility of the hydrocarbon wax can be enhanced, the heat-resistant storage stability of the toner can be further enhanced, and the adhesion of the toner to the developing roller can be further suppressed.

[0032] Hereinafter, each material constituting the toner according to this embodiment will be described. <Binding resin> The binder resin contained in the toner particles according to this embodiment is not particularly limited, but a polyester resin can be suitably used.

[0033] The polyester resin used in the binder resin is usually obtained by polycondensation reaction of one or more selected from a dihydric alcohol component and a trihydric or higher polyhydric alcohol component with one or more selected from a divalent carboxylic acid and a trihydric or higher polycarboxylic acid by a known method via an esterification reaction or an ester exchange reaction.

[0034] The conditions for the polycondensation reaction may be appropriately set depending on the reactivity of the monomer components, and the reaction may be terminated when the polymer has suitable physical properties. For example, the reaction temperature is about 170° C. to 250° C., and the reaction pressure is about 5 mmHg to normal pressure.

[0035] Examples of the dihydric alcohol component include alkylene oxide adducts of bisphenol A such as polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(3.3)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2.0)-polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, and polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane; Examples of the diols include glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; bisphenol A; propylene adducts of bisphenol A; ethylene adducts of bisphenol A; and hydrogenated bisphenol A.

[0036] Examples of trihydric or higher polyhydric alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose (cane sugar), 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

[0037] In the toner according to the present embodiment, one of the dihydric alcohol components and the trihydric or higher polyhydric alcohol components may be used alone, or two or more of them may be used in combination.

[0038] Examples of divalent carboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, n-dodecylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid, and acid anhydrides and lower alkyl esters thereof.

[0039] Examples of trivalent or higher polyvalent carboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-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, and acid anhydrides and lower alkyl esters thereof.

[0040] In the toner according to the present embodiment, one of the divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids may be used alone, or two or more of them may be used in combination.

[0041] The weight average molecular weight of the polyester resin is preferably 3000 to 50000. If the weight average molecular weight is less than the lower limit, the peelability at the high temperature side of the fixable temperature range may be poor. On the other hand, if the weight average molecular weight is more than the upper limit, the low temperature fixability may be poor.

[0042] The polyester resin preferably has an acid value of 5 mgKOH / g or more and 30 mgKOH / g or less. If the acid value is less than the lower limit, the electrostatic chargeability of the polyester resin decreases, and the electrostatic control agent becomes difficult to disperse in the polyester resin, which may adversely affect the electrostatic rise property and the electrostatic stability during continuous printing. On the other hand, if the acid value exceeds the upper limit, the electrostatic chargeability may become unstable due to high hygroscopicity.

[0043] <Styrene-based resin> The toner particles according to the present embodiment contain a styrene-based resin. The styrene-based resin is dispersed in the binder resin and exists as dispersed particles. By adding (internal adding) the styrene-based resin to the toner particles, it is possible to impart fluidity to the toner.

[0044] Examples of styrene-based resins include homopolymers of styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, ethylstyrene, isopropylstyrene, and dimethylstyrene, and copolymers thereof, as well as copolymers of vinyl monomers and styrene-based monomers that can be copolymerized with styrene-based monomers. Examples of vinyl monomers include monofunctional monomers such as alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate, (meth)acrylonitrile, and bifunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate. Here, "(meth)acrylate" means acrylate or methacrylate. Among these styrene-based resins, copolymers of styrene or α-methylstyrene and (meth)acrylate (styrene-acrylic copolymers) are preferred.

[0045] The content of the styrene resin in the toner particles according to the present embodiment is preferably 5 to 10 times, and more preferably 6 to 8 times, the content of the ester wax as an encapsulation promoter. By keeping the content ratio within the above range, the dispersibility of the styrene resin can be improved, and the heat-resistant storage stability of the toner and the fixability at the high temperature side of the fixable temperature range can be further improved.

[0046] The content of the styrene resin in the toner particles is preferably from 3.5% by mass to 7% by mass, and more preferably from 4% by mass to 6% by mass.

[0047] The glass transition temperature of the styrene resin is preferably 70°C or lower, and more preferably 50°C or higher and 70°C or lower.

[0048] The SP value of the styrene-based resin is preferably 8.0 or more and 11.5 or less, and more preferably 9.0 or more and 10.0 or less.

[0049] <Hydrocarbon wax> The toner particles according to the present embodiment contain a hydrocarbon wax as a release agent. As shown in the toner particle T on the right side of Fig. 1, the toner particles according to the present embodiment also contain an ester wax as an encapsulation promoter, so that the proportion of "hydrocarbon wax encapsulated in styrene resin" in the "total amount of hydrocarbon wax added to the toner particles" is high.

[0050] The hydrocarbon wax is a wax composed of carbon atoms and hydrogen atoms, and examples thereof include polyethylene wax, polypropylene wax, paraffin wax, Fischer-Tropsch wax, and microcrystalline wax. Among these hydrocarbon waxes, paraffin wax is preferred. These waxes may be used alone or in combination of two or more.

[0051] The content of the hydrocarbon wax in the toner particles according to the present embodiment is preferably 2 to 5 times, and more preferably 2 to 4 times, the content of the ester wax as an encapsulation promoter. By keeping the content ratio within the above range, the dispersibility of the hydrocarbon wax can be improved, the heat-resistant storage stability of the toner can be further improved, and the burning of the toner onto the developing roller can be further suppressed.

[0052] The content of the hydrocarbon wax in the toner particles is preferably from 1.5% by mass to 3.5% by mass, and more preferably from 2% by mass to 3% by mass.

[0053] The melting point of the hydrocarbon wax is preferably 60°C or higher and 100°C or lower, and more preferably 60°C or higher and 80°C or lower.

[0054] The SP value of the hydrocarbon wax is preferably 7.5 or more and 9.5 or less, and more preferably 8.0 or more and 8.5 or less.

[0055] <Ester wax> The toner particles according to the present embodiment contain an ester wax as an encapsulation promoter.

[0056] Here, the encapsulation promoter refers to a substance that brings about the effect of bringing together the hydrocarbon wax and the styrene resin, and by extension, brings about the effect of increasing the proportion of the hydrocarbon wax encapsulated in the dispersed particles of the styrene resin, and the effect of enhancing the dispersibility of the styrene resin and the hydrocarbon wax. Since the ester wax can exert the effect of enhancing the dispersibility by itself, the encapsulation promoter in this specification refers to the ester wax.

[0057] As the ester wax, for example, Nissan Electol WEP-5, WEP-14, WEP-15, WE-15 (all trade names) manufactured by NOF Corporation, and the like can be used.

[0058] The content of the ester wax in the toner particles according to the present embodiment is preferably 0.2% by mass to 1% by mass, more preferably 0.5% by mass to 0.9% by mass. When the content of the ester wax is within the above range, the hydrocarbon wax is easily encapsulated in the styrene resin, which enhances the heat-resistant storage stability of the toner and prevents the toner from burning onto the developing roller.

[0059] The melting point of the ester wax is preferably 70°C or higher and 110°C or lower, and more preferably 70°C or higher and 80°C or lower.

[0060] The SP value of the ester wax is preferably 8.0 or more and 9.5 or less, and more preferably 8.5 or more and 9.0 or less.

[0061] <Coloring agent> The toner particles according to the present embodiment may contain a colorant. As the colorant, organic pigments, organic dyes, inorganic pigments, inorganic dyes, and the like used in the field of electrophotography can be used.

[0062] Examples of black colorants include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite, and magnetite.

[0063] Examples of yellow colorants include CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, CI Pigment Yellow 180, and CI Pigment Yellow 185.

[0064] Examples of magenta colorants include CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, and CI Pigment Red 222.

[0065] Examples of cyan colorants include CI Pigment Blue 15, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 16, CI Pigment Blue 60, and the like.

[0066] The content of the colorant in the toner particles is preferably 3 parts by mass or more and 10 parts by mass or less. The colorant may be used in the form of a master batch in order to disperse it uniformly in the binder resin.

[0067] <Charge control agent> The toner particles according to the present embodiment may contain a charge control agent. The charge control agent is added to impart a preferable chargeability to the toner. The charge control agent is not particularly limited, and charge control agents for positive charge control and negative charge control used in the field of electrophotography can be used.

[0068] Examples of charge control agents for controlling positive charges include quaternary ammonium salts, pyrimidine compounds, triphenylmethane derivatives, guanidine salts, and amidine salts.

[0069] Charge control agents for negative charge control include metal-containing azo compounds, azo complex dyes, metal complexes and metal salts of salicylic acid and its derivatives (metals include chromium, zinc, zirconium, etc.), organic bentonite compounds, and boron compounds.

[0070] These charge control agents may be used alone or in combination of two or more. The content of the charge control agent in the toner particles is preferably 0.5% by mass or more and 5% by mass or less.

[0071] 2.External additives The toner according to the present embodiment may have an external additive attached to the surface of the toner particles. The functions of the external additive include improving the powder flowability, triboelectric charging property, heat-resistant storage stability, and cleaning property of the toner, and controlling the wear property of the photoreceptor surface.

[0072] As the external additive, for example, inorganic fine particles having an average primary particle size of 5 nm to 200 nm, such as silica, titanium oxide, alumina, etc., can be used. Inorganic fine particles whose surfaces have been given hydrophobicity by surface treatment with a silane coupling agent, a titanium coupling agent, or silicone oil are more suitable because they are less susceptible to reduction in electrical resistance and charge amount in a high humidity environment.

[0073] The content of the external additive is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 3 parts by mass, per 100 parts by mass of the toner particles. If the content of the external additive is less than the lower limit, it becomes difficult to impart the effect of improving the fluidity. If the content of the external additive is more than the upper limit, the fixing property may decrease.

[0074] As a method for adding an external additive to toner particles, a method in which the toner particles and the external additive are mixed in an air flow mixer such as a Henschel mixer can be mentioned. EXAMPLES

[0075] The toner of the present disclosure will be specifically described below based on examples and comparative examples. First, various measurement methods and evaluation methods will be described.

[0076] 1. Measurement and evaluation methods -Method for measuring the average dispersion diameter and inclusion rate of styrene-based resin and hydrocarbon-based wax- The toner particles of the examples and comparative examples were embedded in a room temperature curable epoxy resin, and the cured product was subjected to surface processing using an ultramicrotome (manufactured by Reichert, product name: Ultracut N) equipped with diamond teeth. The cross section of the obtained toner particle was observed using a scanning transmission electron microscope (manufactured by Hitachi High-Technologies Corporation, model: S-4800). A considerable number (20 to 30 pieces) of dispersed particles of styrene-based resin of 50 nm or more were randomly extracted from the electron microscope photograph data, and the images were analyzed using image analysis software (product name: A-zo-kun, manufactured by Asahi Kasei Engineering Co., Ltd.) to determine the average dispersion diameter of the styrene-based resin dispersed in the toner particles and the average dispersion diameter of the hydrocarbon-based wax encapsulated in the styrene-based resin (dispersed in the styrene-based resin).

[0077] The encapsulation rate was calculated from the particle diameter of the dispersed particles of the styrene resin (dispersion diameter of the styrene resin) and the average dispersion diameter of the hydrocarbon wax encapsulated in the dispersed particles of the styrene resin. In other words, the encapsulation rate is the volume ratio of the hydrocarbon wax in the dispersed particles of the styrene resin. However, since it is calculated based on the average dispersion diameter obtained from the electron microscope photograph data as described above, the measurement is an area ratio.

[0078] Specifically, the dispersed particles of the styrene resin dispersed in the binder resin (main resin) of the toner particles were randomly selected, and the area calculated from the average dispersed diameter of the hydrocarbon wax dispersed therein was divided by the area calculated from the dispersed diameter of the randomly selected dispersed particles of the styrene resin to calculate the inclusion ratio of the hydrocarbon wax in the dispersed particles. Furthermore, 30 dispersed particles of the styrene resin were randomly selected, and the inclusion ratio of each dispersed particle was calculated, and the average value of these was used as the inclusion ratio in this embodiment and the comparative example.

[0079] -Method of measuring SP value- The SP value was measured according to the method of Suh and Clarke (KW Suh, DH Clarke, "Cohesive Energy Densities of Polymers from Turbidimetric Titrations", Journal of Polymer Science, A-1, vol. 5, 1967, pp. 1671-1681) as follows.

[0080] 0.5 g of the resin to be measured was weighed into a 100 mL beaker, 10 mL of a good solvent (a mixed solution of dioxane and acetone) was added using a volumetric pipette, and the resin was dissolved by stirring using a magnetic stirrer. A hydrophobic solvent (a mixed solution of n-hexane and ion-exchanged water) was then added dropwise to the resin using a 50 mL burette, and the amount added was determined to be the point at which turbidity occurred at a measurement temperature of 20°C.

[0081] From the measured values, the SP value δ of the resin was calculated by the following formula. δ=(Vl / 2δl+Vh / 2δh) / (Vl / 2+Vh / 2) In the above formula, Vl is the molar volume (mL / mol) of the solvent in the low SP solvent (hydrophobic solvent) mixed system, Vh is the molar volume (mL / mol) of the solvent in the high SP solvent (good solvent) mixed system, δl is the SP value of the solvent in the low SP solvent (hydrophobic solvent) mixed system, and δh is the SP value of the solvent in the high SP solvent (good solvent) mixed system.

[0082] - Fixability evaluation method (evaluation at the high temperature end of the fixable temperature range) - A fixed image was formed using a two-component developer using a commercially available copying machine (model: MX-5100FN, manufactured by Sharp Corporation) modified for evaluation. First, a sample image including a solid image (rectangle of 20 mm length and 50 mm width) was formed as an unfixed image on recording paper (model: SF-4AM3, manufactured by Sharp Corporation, PPC paper). At this time, the amount of toner adhering to the recording paper in the solid image was 1.0 mg / cm. 2 It was adjusted to be.

[0083] Next, a fixed image was created using a belt fixing device. The fixing process speed was set to 283 mm / sec, and the temperature of the fixing belt was increased in 5°C increments from 110°C to determine the minimum temperature at which high-temperature offset did not occur. Note that "high-temperature offset" refers to the occurrence of toner that is not fixed to the recording paper during fixing and remains attached to the fixing belt, and then adheres to the recording paper after the fixing belt has made one revolution.

[0084] Based on the minimum temperature measured, the "fixability" was evaluated as follows. ◎ (Excellent): The minimum temperature is 195°C or higher. ○ (Good): The minimum temperature is 185°C or higher and less than 195°C. △(Acceptable): The minimum temperature is 175℃ or higher and less than 185℃. × (Not acceptable): The minimum temperature is less than 175°C.

[0085] -Method for evaluating heat resistance storage stability- The heat resistance storage stability was evaluated based on the presence or absence of aggregates after high-temperature storage. 20 g of toner (toner after external addition process) was sealed in a plastic container and left at 50°C for 72 hours, after which the toner was taken out and sieved through a 230 mesh sieve. The weight of the toner remaining on the sieve was measured, and the remaining amount, which is the ratio of this weight to the total weight of the toner, was calculated.

[0086] Based on the measured remaining amount, the "heat-resistant storage stability" was evaluated according to the following criteria. ◎ (Excellent): No aggregation. Residual amount is less than 0.5%. ○ (Good): Minor amount of aggregation. The remaining amount is 0.5% or more and less than 7%. △ (Fair): A large amount of aggregation. The remaining amount is 7% or more and less than 12%. × (Fail): Large amount of aggregation. Residual amount is 12% or more.

[0087] - Method for evaluating image sticking phenomenon on developing rollers - The prepared two-component developer and toner were filled into the developing device and toner cartridge of a color multifunction printer (Model: MX-2640, manufactured by Sharp Corporation), respectively, and a continuous print test of 50,000 sheets was performed in an environment of 30°C and 80% humidity so that a square solid image (ID=1.45-1.50) with a side length of 1 cm was formed at three positions, the center and both ends in the axial direction of the developing roller.

[0088] Based on this continuous printing test, the image sticking phenomenon was evaluated according to the following criteria. ⊚ (Excellent): There is no decrease in density from the initial image to the 50,000th image, and no toner melting onto the developing roller surface. ◯ (Good): There is no decrease in density from the initial image to the 50,000th image, but some fusion of toner is observed on the surface of the developing roller. Δ (Fair): There is no decrease in density from the initial image to the 50,000th image, but toner is fused to the surface of the developing roller. × (unacceptable): There is a decrease in density from the initial image to the 50,000th image, and toner is fused to the surface of the developing roller.

[0089] 2. Toner manufacturing example First, the following Tables 1 to 3 show the physical properties of the styrene-based resins, hydrocarbon-based waxes, and ester waxes serving as encapsulation promoters used in the examples and comparative examples.

[0090] [Table 1]

[0091] [Table 2]

[0092] [Table 3]

[0093] [Example 1] -Toner particle production process- The following toner materials were used to prepare the toner particles (toner cores). ·resin Binder resin: Amorphous polyester resin 84.8% by mass Styrene-based resin A 5% by mass Coloring agents Carbon black (product name: Regal 330, manufactured by Cabot Corporation) 6% by mass Release agent Hydrocarbon wax A (product name: HNP10, manufactured by Nippon Seiro Co., Ltd.) 2.5% by mass Encapsulation promoter Ester wax A (product name: WE-15, manufactured by NOF Corporation) 0.7% by mass Charge control agent Boron compound (product name: LR-147, manufactured by Nippon Cartridge Co., Ltd.) 1% by mass

[0094] The above materials were premixed for 5 minutes using a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd., model: FM20C), and then melt-kneaded using a twin-screw extruder at a cylinder setting temperature of 110°C, a barrel rotation speed of 300 rpm, and a material supply rate of 20 kg / hour to obtain a molten kneaded product.

[0095] The resulting molten and kneaded product was cooled with a cooling belt, then coarsely pulverized using a cutting mill, then finely pulverized using a jet pulverizer, and further classified using an air classifier to obtain toner particles having an average particle size of 6.7 μm.

[0096] -External addition process- To 100 parts by mass of the obtained toner particles, 1.0 part by mass of silica particles (product name: R976, manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 7 nm) was added, and the mixture was stirred for 2 minutes using a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd., model: FM20C) with the tip speed of the stirring blade set to 40 m / sec, to obtain the toner of Example 1.

[0097] - Two-component developer manufacturing process - The toner obtained in the external addition step was mixed with a resin-coated carrier so that the toner concentration relative to the total amount of the two-component developer was 7% by mass, thereby obtaining a two-component developer with a toner concentration of 7% by mass.

[0098] [Examples 2 to 24, Comparative Examples 1 to 7] A toner and a two-component developer were obtained in the same manner as in Example 1, except that the types (physical properties), amounts added, and average dispersion diameters of the "styrene-based resin," "hydrocarbon-based wax," and "ester wax as an encapsulation promoter" used were changed as shown in Table 4 below.

[0099] [Table 4]

[0100] [Table 5]

[0101] Table 5 shows the evaluation results of the examples and comparative examples. In Examples 1 to 24, the toner particles contain a styrene resin dispersed in a binder resin, a hydrocarbon wax dispersed in the styrene resin, and an ester wax as an encapsulation promoter. Further, the average dispersion diameter of the styrene resin is 200 nm or more and 900 nm or less, the average dispersion diameter of the hydrocarbon wax is smaller than the average dispersion diameter of the styrene resin and is 50 nm or more and 300 nm or less, and the encapsulation ratio, which is the volume ratio of the hydrocarbon wax in the dispersed particles of the styrene resin, is 20% or more and 50% or less. As is clear from the evaluation results in Table 5, Examples 1 to 24 that satisfy these requirements can achieve both fixability and heat-resistant storage stability in the low-temperature fixing toner, and can suppress sticking to the developing roller.

[0102] On the other hand, Comparative Examples 1 to 7 that do not satisfy these requirements were inferior to the examples in the evaluation results of fixability, heat-resistant storage stability, and the sticking phenomenon to the developing roller.

[0103] When the SP value of the styrene resin is SP1, the SP value of the hydrocarbon wax is SP2, and the SP value of the encapsulation promoter (ester wax) is SP3, it can be seen that Examples 1 and the like that satisfy the relationship of SP2 < SP3 < SP1 are superior in the evaluation of various items to Example 8 where SP3 < SP2 < SP1 and Example 9 where SP1 = SP2 < SP3.

[0104] Examples 1 and the like that satisfy the relationships of the following formulas (1) and (2) are particularly superior in the evaluation of heat-resistant storage stability and the sticking phenomenon to the developing roller compared to Example 10 where SP3 - SP2 exceeds 1.0 and does not satisfy the relationship of the following formula (1), and Example 11 where SP1 - SP3 exceeds 1.0 and does not satisfy the relationship of the following formula (2). SP3 - SP2 ≤ 1.0 ···(1) SP1 - SP3 ≤ 1.0 ···(2)

[0105] When the melting point of the hydrocarbon wax is T1 and the melting point of the encapsulation promoter (ester wax) is T2, it can be seen that Examples 1 etc. that satisfy the relationship T1 < T2 are particularly superior in the evaluation of heat-resistant storage stability compared to Example 12 that does not satisfy this relationship.

[0106] Examples 1, 13, 14 etc. where the content of the encapsulation promoter (ester wax) in the toner particles is 0.2 mass% or more and 1 mass% or less are particularly superior in the evaluation of the sticking phenomenon to the developing roller compared to Examples 15, 16 where the content is outside the above range.

[0107] Examples 1, 17, 18 etc. where the content of the hydrocarbon wax in the toner particles is 2 times or more and 5 times or less the content of the encapsulation promoter (ester wax) are particularly superior in the evaluation of fixability (high-temperature offset) compared to Example 19 where the ratio of the content is less than the above lower limit, and it can be seen that they are particularly superior in the evaluation of heat-resistant storage stability and the sticking phenomenon to the developing roller compared to Example 20 where the ratio of the content exceeds the above upper limit.

[0108] Examples 21, 22 where the content of the styrene resin in the toner particles is 5 times or more and 10 times or less the content of the encapsulation promoter (ester wax) are particularly superior in the evaluation of heat-resistant storage stability and the sticking phenomenon to the developing roller compared to Example 23 where the ratio of the content is less than the above lower limit, and it can be seen that they are particularly superior in the evaluation of fixability (high-temperature offset) compared to Example 24 where the ratio of the content exceeds the above upper limit.

[0109] All the embodiments disclosed this time are illustrative in all respects and do not serve as a basis for a restrictive interpretation. Therefore, the technical scope of the present disclosure is not interpreted only by the above-described embodiments, but is defined based on the description in the claims. Also, all changes within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0110] 1 Binder resin 2 Hydrocarbon wax 3 Styrene resin 4. Encapsulation promoter (ester wax) T Toner particles

Claims

1. A toner having toner particles containing a binder resin, the toner particles contain a styrene-based resin dispersed in the binder resin, a hydrocarbon-based wax dispersed in the styrene-based resin, and an ester wax as an encapsulation promoter; The average dispersion diameter of the styrene-based resin is 200 nm or more and 900 nm or less, the average dispersion diameter of the hydrocarbon wax is smaller than the average dispersion diameter of the styrene resin and is 50 nm or more and 300 nm or less; The toner is characterized in that an inclusion rate, which is a volume ratio of the hydrocarbon wax in dispersed particles of the styrene resin, is 20% or more and 50% or less.

2. 2. The toner according to claim 1, If the SP value of the styrene-based resin is SP1, the SP value of the hydrocarbon-based wax is SP2, and the SP value of the ester wax is SP3, A toner satisfying the relationship SP2<SP3<SP1.

3. The toner according to claim 2, A toner characterized by satisfying the relationships of the following formulas (1) and (2): SP3-SP2≦1.0...(1) SP1-SP3≦1.0...(2)

4. The toner according to claim 1 or 2, When the melting point of the hydrocarbon wax is T1 and the melting point of the ester wax is T2, A toner satisfying the relationship T1<T2.

5. The toner according to claim 1 or 2, The toner, wherein the content of the ester wax in the toner particles is 0.2% by mass or more and 1% by mass or less.

6. The toner according to claim 1 or 2, The toner according to the present invention is characterized in that the content of the hydrocarbon wax in the toner particles is from 2 to 5 times the content of the ester wax.

7. The toner according to claim 1 or 2, The toner, wherein the content of the styrene resin in the toner particles is 5 to 10 times the content of the ester wax.

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