JP6859913B2 - toner - Google Patents

Description

The present invention relates to toner, and more particularly to capsule toner in which toner particles have a shell layer.

In the toner described in Patent Document 1, the toner mother particles include a binder resin (binder resin), cellulose nanofibers, a colorant, and a mold release agent. The binder resin contains at least a polyester resin A composed of benzenedicarboxylic acid, disproportionate rosin and glycerin, and a polyester resin B composed of at least a benzenedicarboxylic acid and a bisphenol A derivative. Cellulose nanofibers having a number average fiber length of 50 to 500 μm are internally added to the toner mother particles.

Japanese Unexamined Patent Publication No. 2013-44886

In the technique described in Patent Document 1, the cellulose nanofibers having a number average fiber length of 50 to 500 μm are inserted into the toner mother particles by utilizing the fact that the hydroxyl group of the glycol in the binder resin easily binds to the cellulose nanofibers. This improves the blocking property of the toner. However, Patent Document 1 only discloses the use of general cellulose nanofibers having a long fiber length, and there is still room for improvement in the technique of applying nanocellulose to toner. The fiber length of general cellulose nanofibers is 5 μm or more.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the coating state of the shell layer by nanocellulose and to provide a toner suitable for image formation.

The toner according to the present invention contains a plurality of toner particles including a composite core and a shell layer covering the surface of the composite core. The composite core is a composite of a toner core and a plurality of nanocellulose particles adhering to the surface of the toner core, respectively. Each of the plurality of nanocellulose particles is one or more types of nanocellulose particles selected from the group consisting of cellulose nanofiber particles and cellulose nanocrystal particles. In the plurality of nanocellulose particles, the width of the nanocellulose particles is 20 nm or more and 50 nm or less on a number average, and the length of the nanocellulose particles is 500 nm or less on a number average.

According to the present invention, it becomes possible to improve the coating state of the shell layer by nanocellulose and provide a toner suitable for image formation.

It is a figure which shows an example of the cross-sectional structure of the toner particle contained in the toner which concerns on embodiment of this invention.

An embodiment of the present invention will be described. The evaluation results (values indicating the shape or physical properties, etc.) of the powder (more specifically, the toner core, the toner matrix particles, the external additive, the toner, etc.) are included in the powder unless otherwise specified. It is the number average of the values measured for a considerable number of particles contained.

Unless otherwise specified, the average particle size of the powder is the average number of the circle-equivalent diameter of the primary particles (Haywood diameter: the diameter of the circle having the same area as the projected area of the particles) measured using a microscope. The value. Unless otherwise specified, the measured value of the medium volume diameter (D ₅₀ ) of the powder is measured using a laser diffraction / scattering type particle size distribution measuring device (“LA-750” manufactured by HORIBA, Ltd.). It is the value that was calculated.

The glass transition point (Tg) is a value measured according to "JIS (Japanese Industrial Standards) K7121-2012" using a differential scanning calorimeter ("DSC-6220" manufactured by Seiko Instruments Inc.) unless otherwise specified. Is. In the heat absorption curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) measured by the differential scanning calorimeter, the temperature of the inflection point due to the glass transition (specifically, the external line and the falling edge of the baseline). The temperature at the intersection of the line with the extra line) corresponds to Tg (glass transition point). The softening point (Tm) is a value measured using an heightened flow tester (“CFT-500D” manufactured by Shimadzu Corporation) unless otherwise specified. In the S-curve (horizontal axis: temperature, vertical axis: stroke) measured by the heightened flow tester, the temperature that becomes "(baseline stroke value + maximum stroke value) / 2" becomes Tm (softening point). Equivalent to.

The chargeability means the chargeability in triboelectric charging, unless otherwise specified. The strength of positive charging (or the strength of negative charging) in triboelectric charging can be confirmed by a well-known charging train or the like.

The "main component" of a material, unless otherwise specified, means the component most abundant in the material on a mass basis.

Hereinafter, the compound and its derivative may be collectively referred to by adding "system" after the compound name. When the polymer name is represented by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative. In addition, acrylic and methacrylic may be collectively referred to as "(meth) acrylic".

In the specification of the present application, both untreated silica particles (hereinafter referred to as "silica substrate") and silica particles obtained by surface-treating a silica substrate (that is, surface-treated silica particles) are both "silica". Described as "particle". Further, silica particles hydrophobized with a surface treatment agent may be referred to as "hydrophobic silica particles", and silica particles positively charged with a surface treatment agent may be referred to as "positively charged silica particles". Both untreated titanium oxide particles (hereinafter referred to as "titanium oxide substrate") and titanium oxide particles in which the titanium oxide substrate is covered with a conductive layer (specifically, titanium oxide particles imparted with conductivity by a coating layer). , Described as "titanium oxide particles".

The toner according to this embodiment can be suitably used for developing an electrostatic latent image, for example, as a positively charged toner. The toner of this embodiment is a powder containing a plurality of toner particles (particles having a configuration described later). The toner may be used as a one-component developer. Further, a two-component developer may be prepared by mixing the toner and the carrier using a mixing device (more specifically, a ball mill or the like). In order to form a high-quality image, it is preferable to use a ferrite carrier (specifically, a powder of ferrite particles) as a carrier. Further, in order to form a high-quality image for a long period of time, it is preferable to use magnetic carrier particles including a carrier core and a resin layer covering the carrier core. In order to impart magnetism to the carrier particles, the carrier core may be formed of a magnetic material (for example, a ferromagnetic substance such as ferrite), or the carrier core may be formed of a resin in which the magnetic particles are dispersed. Good. Further, the magnetic particles may be dispersed in the resin layer covering the carrier core. In order to form a high-quality image, the amount of toner in the two-component developer is preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the carrier. The positively charged toner contained in the two-component developer is positively charged by friction with the carrier.

The toner particles include a core (hereinafter, referred to as “toner core”) and a shell layer (capsule layer) formed on the surface of the toner core. The toner core contains a binder resin. If necessary, an internal additive (for example, at least one of a release agent, a colorant, a charge control agent, and a magnetic powder) may be dispersed in the binder resin of the toner core. The shell layer is substantially composed of resin. For example, by covering the toner core that melts at a low temperature with a shell layer having excellent heat resistance, it is possible to achieve both heat-resistant storage stability and low-temperature fixability of the toner. Additives may be dispersed in the resin constituting the shell layer. The shell layer may cover the entire surface of the toner core or may partially cover the surface of the toner core. An external additive may be attached to the surface of the shell layer (or the surface area of the toner core not covered by the shell layer). If it is not necessary, the external additive may be omitted. Toner particles that do not have a shell layer may be mixed in the toner that mainly contains toner particles that include a shell layer (for example, the toner particles are contained in a proportion of 80% by number or more). Hereinafter, the toner particles before the external additive is attached will be referred to as "toner mother particles". Further, the material for forming the shell layer is described as "shell material".

The toner according to this embodiment can be used for forming an image in, for example, an electrophotographic apparatus (image forming apparatus). Hereinafter, an example of an image forming method using an electrophotographic apparatus will be described.

First, an image forming unit (for example, a charging device and an exposure device) of an electrophotographic apparatus forms an electrostatic latent image on a photoconductor (for example, a surface layer portion of a photoconductor drum) based on image data. Subsequently, a developing device of an electrophotographic apparatus (specifically, a developing device filled with a developer containing toner) supplies toner to the photoconductor to develop an electrostatic latent image formed on the photoconductor. The toner is charged by friction with a carrier, developing sleeve, or blade in the developing apparatus before being fed to the photoconductor. For example, positively charged toner is positively charged. In the developing process, toner (specifically, charged toner) on a developing sleeve (for example, the surface layer of a developing roller in a developing device) arranged in the vicinity of the photoconductor is supplied to the photoconductor, and the supplied toner is supplied. A toner image is formed on the photoconductor by adhering to the electrostatic latent image of the photoconductor. An amount of toner corresponding to the amount of toner consumed in the developing process is replenished from the toner container containing the replenishing toner to the developing apparatus.

In the subsequent transfer step, the transfer device of the electrophotographic apparatus transfers the toner image on the photoconductor to an intermediate transfer body (for example, a transfer belt), and then further transfers the toner image on the intermediate transfer body to a recording medium (for example, paper). Transfer to. After that, the fixing device of the electrophotographic apparatus (fixing method: nip fixing by a heating roller and a pressure roller) heats and pressurizes the toner to fix the toner on the recording medium. As a result, an image is formed on the recording medium. For example, a full-color image can be formed by superimposing toner images of four colors of black, yellow, magenta, and cyan. After the transfer step, the toner remaining on the photoconductor is removed by a cleaning member (for example, a cleaning blade). The transfer method may be a direct transfer method in which the toner image on the photoconductor is directly transferred to a recording medium without going through an intermediate transfer body.

The toner according to this embodiment has the following configuration (hereinafter, referred to as “basic configuration”).

(Basic composition of toner)
The toner contains a plurality of toner particles including a toner mother particle and an external additive adhering to the surface of the toner mother particle. The toner mother particles include a composite core and a shell layer that covers the surface of the composite core. The composite core is a composite of a toner core and a plurality of nanocellulose particles attached to the surface of the toner core, respectively. Each of the plurality of nanocellulose particles is one or more types of nanocellulose particles selected from the group consisting of cellulose nanofiber particles and cellulose nanocrystal particles. Among the plurality of nanocellulose particles, the width of the nanocellulose particles is 20 nm or more and 50 nm or less on a number average, and the length of the nanocellulose particles is 500 nm or less on a number average. Hereinafter, cellulose nanofiber particles may be referred to as “CNF particles”, and cellulose nanofiber powder (that is, powder of CNF particles) may be referred to as “CNF powder”, respectively. Further, the cellulose nanocrystal particles may be described as "CNC particles", and the cellulose nanocrystal powder (that is, the powder of CNC particles) may be described as "CNC powder".

In the above basic configuration, the "width" and "length" of the particles are values measured based on a two-dimensional projection image (specifically, an SEM photograph) of the particles, respectively. The "length" of a particle is the length of the major axis of the particle (major axis diameter), and more specifically, corresponds to the width of the particle in which the distance between two parallel lines sandwiching the particle is maximized. .. The "width" of a particle is the length of the minor axis of the particle (minor axis diameter), and more specifically, it is measured on a straight line that passes through the midpoint of the major axis and is orthogonal to the major axis. Corresponds to the width of the particles to be formed. The "aspect ratio" corresponds to a value (= major axis diameter / minor axis diameter) obtained by dividing the length (major axis diameter) by the width (minor axis diameter).

When cellulose is hydrogen-bonded and crystallized, it becomes nanocellulose (specifically, fine cellulose fibers having a thickness of 1 nm or more and 100 nm or less) and exhibits extremely high strength. Nanocellulose has many hydroxyl groups in its molecular structure. Cellulose nanofibers are derived from cellulose raw materials (eg, wood) by mechanical treatment (more specifically, crushing treatment with a bead mill, etc.) or chemical treatment (more specifically, TEMPO-catalyzed oxidation, carboxymethylation, or Nanocellulose extracted by cationization, etc.). Cellulosic nanocrystals are obtained by hydrolyzing and removing non-crystalline portions of cellulose raw materials (eg, wood) using high concentrations of mineral acids (eg, strong acids such as hydrochloric acid, sulfuric acid, or hydrobromic acid). Nanocellulose in which only the crystalline portion is isolated.

The inventor of the present application has found that nanocellulose (specifically, CNF powder and CNC powder) can be uniformly adhered to the surface of a toner core by adjusting the dimensions of nanocellulose. Specifically, the inventor of the present application uniformly adheres nanocellulose powder (CNF powder and / or CNC powder) having the particle width and particle length defined in the above-mentioned basic configuration to the surface of the toner core. Successful. Such nanocellulose powder acts to improve the chargeability and fixability of the toner. Specifically, nanocellulose particles having a sufficiently short length and an appropriate width (specifically, nanocellulose particles having a number average width of 20 nm or more and 50 nm or less and a number average length of 500 nm or less) are present on the surface of the toner core. Appropriate irregularities are formed on the base of the shell layer, and corresponding irregularities are also formed on the surface of the toner matrix particles. By forming such irregularities on the surface of the toner mother particles, the fluidity of the toner is improved. Further, the unevenness on the surface of the toner mother particles tends to promote the charging of the toner particles by friction and improve the chargeability of the toner. In addition, the nanocellulose particles distort the shell layer, so that the shell layer is easily destroyed in the fixing process. As a result, it is considered that the low temperature fixability of the toner is improved. Further, when the toner mother particles are heated in the fixing step and the toner mother particles are melted, the CNF particles and / or the CNC particles existing on the surface of the toner mother particles act to promote the melting connection between the toner mother particles. To do. Due to the action of the CNF particles and / or the CNC particles, the toner is easily fixed on the paper. In order to make the shell layer in a good coating state, the length of the nanocellulose particles is 50 nm or more on average with respect to the nanocellulose powder existing on the surface of the toner core, and the aspect ratio of the nanocellulose particles is increased. Is particularly preferably 2.0 or more on a numerical average.

In order to appropriately distort the shell layer, the amount of nanocellulose powder is preferably 1.0 part by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the toner core. Excess nanocellulose powder present on the surface of the toner core tends to hinder toner fixation. Further, in order to obtain a toner having excellent fixability, it is preferable that nanocellulose (that is, nanocellulose as an internal additive) does not exist inside the toner core. The coverage of the nanocellulose particles on the surface of the toner core is preferably 40% or more and 80% or less in terms of area ratio.

In order to uniformly form the shell layer on the surface of the composite core, in the above-mentioned basic configuration, the shell layer is a copolymer of at least two or more vinyl compounds containing a compound represented by the following formula (1). It is preferable to contain it.

In formula (1), R ¹ represents a hydrogen atom or an alkyl group which may have a substituent (which may be linear, branched, or cyclic). Examples of the substituent when R ¹ represents an alkyl group having a substituent include a phenyl group. As R ¹ , a hydrogen atom, a methyl group, an ethyl group, or an isopropyl group is preferable, and a hydrogen atom or a methyl group is particularly preferable. For example, in 2-vinyl-2-oxazoline, R ¹ in the formula (1) represents a hydrogen atom.

In the polymer of the vinyl compound, the repeating unit derived from the vinyl compound is considered to be addition-polymerized by the carbon double bond “C = C”. A vinyl compound is a compound having a vinyl group (CH ₂ = CH−) or a group in which hydrogen in the vinyl group is substituted. Examples of vinyl compounds include ethylene, propylene, butadiene, vinyl chloride, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylonitrile, or styrene.

The compound represented by the above formula (1) constitutes a copolymer by addition polymerization in units represented by the following formula (1-1). Hereinafter, the compound represented by the above formula (1) will be referred to as “compound (1)”, and the unit represented by the following formula (1-1) will be referred to as “unit (1-1)”.

In formula (1-1), R ¹ represents the same group as ^{R 1} in formula (1). Unit (1-1) has an unopened ring oxazoline group. The unopened ring oxazoline group has a cyclic structure and exhibits strong positive chargeability. The unopened ring oxazoline group easily reacts with a carboxyl group, an aromatic sulfanil group, and an aromatic hydroxyl group.

In addition, the unopened oxazoline group can also react with the hydroxyl group (-OH) existing on the surface of the nanocellulose particles. For example, when the unit (1-1) in the shell layer ^{reacts with the hydroxyl group of the nanocellulose particles (expressed as R 0 in the} formula (1-2)), the oxazoline group is shown in the following formula (1-2). Opens a ring and a chemical bond (specifically, a covalent bond) is formed between the nanocellulose particles and the shell layer. By forming such a bond, the bond between the nanocellulose particles and the shell layer is strengthened, and it becomes easy to uniformly form a thin shell layer on the surface of the composite core. Hereinafter, the unit represented by the following formula (1-2) will be described as "unit (1-2)".

The shell layer preferably contains a unit (1-1) and a unit (1-2). Unit (1-2) comprises an oxazoline group that has been ring-opened by reaction with a functional group present on the surface of the nanocellulose particles. In formula (1-2), R ¹ represents the same group as ^{R 1} in formula (1-1) ^{, and R 0} represents nanocellulose particles.

The unopened ring oxazoline group has both crosslinkability and positive chargeability. Therefore, by forming the shell layer with the resin containing the unit (1-1) and the unit (1-2), toner particles having excellent positive charge property and sufficient stress resistance can be obtained.

In the above-mentioned basic configuration, when the shell layer contains a copolymer of two or more kinds of vinyl compounds containing at least the compound (1), it is particularly preferable that the toner core contains a polyester resin. When the unit (1-1) in the shell layer reacts with the carboxyl group of the polyester resin, the oxazoline group is ring-opened to form a chemical bond (specifically, a covalent bond) between the toner core and the shell layer. can do. By forming such a bond, the bond between the toner core and the shell layer is strengthened, and it becomes easy to uniformly form a thin shell layer on the surface of the composite core. In addition, cellulose nanofibers and cellulose nanocrystals each have a strong affinity for polyester resin. Therefore, the melting connection between the toner mother particles in the fixing step is easily promoted by the CNF particles and / or the CNC particles.

In order to ensure sufficient toner fluidity and chargeability, in the above-mentioned basic configuration, the toner particles are provided with an external additive containing silica particles having an average number of primary particle diameters of 5 nm or more and 30 nm or less, and the shell layer is provided with an external additive. It is preferable that the thickness is 1 nm or more and 15 nm or less, and on the surface of the toner mother particles, the nanocellulose particles and the shell layer on the nanocellulose particles form convex portions at positions where the nanocellulose particles are present. .. Silica particles having a small particle size (specifically, silica particles having an average number of primary particle diameters of 5 nm or more and 30 nm or less) can easily impart fluidity to the toner. However, silica particles having a small particle size are easily buried in the toner mother particles by an external force. By covering the nanocellulose particles existing on the surface of the toner core with a thin shell layer (specifically, a shell layer having a thickness of 1 nm or more and 15 nm or less), the shell layer is deformed convexly at the position where the nanocellulose particles are present. Due to such deformation of the shell layer, convex portions are formed on the surface of the toner mother particles. Specifically, the nanocellulose particles and the shell layer on the nanocellulose particles form a convex portion on the surface of the toner mother particles at a position where the nanocellulose particles are present. For example, by stirring the toner matrix particles (powder) and the external additive (powder) together, the external additive particles can be adhered to the surface of the toner matrix particles. When the external additive particles are attached to the surface of the toner matrix particles by such a method, the external additive particles having a small particle size are flat regions on the surface of the toner matrix particles (specifically, regions in which convex portions are not formed). Tends to adhere to. The presence of the convex portion makes it difficult for stress to be applied to the external additive particles (particularly, the external additive particles having a small particle size) existing in the flat region, and the embedding of the external additive particles in the toner mother particles is suppressed. Toner.

The thickness of the shell layer can be measured by analyzing a TEM (transmission electron microscope) image of a cross section of toner particles using commercially available image analysis software (for example, "WinROOF" manufactured by Mitani Shoji Co., Ltd.). If the thickness of the shell layer is not uniform in one toner particle, two straight lines orthogonal to each other at substantially the center of the cross section of the toner particle are drawn at four evenly spaced points (specifically, two straight lines are drawn). The thickness of the shell layer is measured at each of the four points where the straight line intersects the shell layer), and the arithmetic mean of the obtained four measured values is taken as the evaluation value (thickness of the shell layer) of the toner particles. The thickness of the shell layer corresponds to the dimension from the surface of the toner core to the surface of the shell layer in the region where nanocellulose particles do not exist at the interface between the toner core and the shell layer, and the thickness of the nanocellulose at the interface between the toner core and the shell layer. In the region where the particles are present, it corresponds to the dimension from the surface of the nanocellulose particles to the surface of the shell layer. If the boundary between the composite core and the shell layer is unclear in the TEM image, a feature included in the shell layer in the TEM image by combining TEM and electron energy loss spectroscopy (EELS). By mapping the elements, the boundary between the composite core and the shell layer can be clarified.

In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, it is preferable that the coverage of the shell layer on the surface of the composite core is 80% or more and 100% or less in terms of area ratio. The coverage (unit:%) of the shell layer is expressed by the formula “coverage of shell layer = 100 × (area of core covering area) / (area of surface area of composite core)”. In the formula, the "area of the surface area of the composite core" corresponds to the sum of the area of the core covering area and the area of the core exposed area. The “core covering region” corresponds to the region covered by the shell layer in the surface region of the composite core, and the “core exposed region” corresponds to the region not covered by the shell layer in the surface region of the composite core. When the coverage of the shell layer is 100%, it means that the entire surface of the composite core is covered with the shell layer. The coverage of the shell layer can be determined by, for example, analyzing an image of toner particles (for example, pre-stained toner particles) taken with a field emission scanning electron microscope (“JSM-7600F” manufactured by JEOL Ltd.). Can be measured. The core covering region and the other region (core exposed region) on the surface of the composite core can be distinguished by, for example, the difference in the brightness value.

Hereinafter, an example of toner particles contained in the toner having the above-mentioned basic configuration will be described with reference to FIG. FIG. 1 shows the surface of toner particles.

The toner particles shown in FIG. 1 include a toner mother particle and a plurality of silica particles 14 (external additives) attached to the surface of the toner mother particle, respectively. The number average primary particle diameter of the plurality of silica particles 14 is, for example, 5 nm or more and 30 nm or less. The toner mother particles include a composite core and a shell layer 12 that covers the surface of the composite core. The composite core is a composite of the toner core 11 and a plurality of nanocellulose particles 13 attached to the surface of the toner core 11, respectively. Each of the plurality of nanocellulose particles 13 exists at the interface between the toner core 11 and the shell layer 12. Each of the plurality of nanocellulose particles 13 is, for example, cellulose nanofiber particles. In the plurality of nanocellulose particles 13, the width of the nanocellulose particles 13 is 20 nm or more and 50 nm or less on a numerical average, and the length of the nanocellulose particles 13 is 500 nm or less on a numerical average. Each of the plurality of nanocellulose particles 13 is fixed to the surface of the toner core 11 with its major axis substantially parallel to the surface of the toner core 11.

The shell layer 12 is, for example, a resin film having a thickness of 1 nm or more and 15 nm or less. By covering the nanocellulose particles 13 existing on the surface of the toner core 11 with the shell layer 12, the shell layer 12 is deformed convexly at the position where the nanocellulose particles 13 are present. In the surface region of the toner mother particles, the region R2 in which the nanocellulose particles 13 exist under the shell layer 12 is higher than the region R1 in which the nanocellulose particles 13 do not exist under the shell layer 12. The surface of the toner matrix particles has a flat region R1 and a convexly raised region R2. The region R1 corresponds to a region where no convex portion is formed. The height of the convex portion of the region R2 with respect to the region R1 is, for example, 35 nm or more and 60 nm or less. The amount of the silica particles 14 adhering to the region R1 is preferably larger than the amount of the silica particles 14 adhering to the region R2.

From the viewpoint of productivity, it is preferable that the nanocellulose powder contains only cellulose nanofiber particles in the above-mentioned basic configuration. Further, in order to obtain a toner suitable for image formation, it is preferable that the main component of the cellulose nanofiber particles is a TEMPO oxide of bleached softwood pulp.

A first method for producing CNF powder includes a chemical method such as a TEMPO-catalyzed oxidation method. Fine needle-shaped nanocellulose particles with a weak external force by oxidizing cellulose fibers with a TEMPO (2,2,6,6-TEtraMethyl Piperidine-1-Oxyradical) catalyst to generate an electrostatic repulsive force between the particles. Will be able to be obtained.

As a second method for producing CNF powder, defibration by a physical method can be mentioned. As the physical method, for example, a high-pressure homogenizer method, a microfluidizer method, a grinder grinding method, a strong shearing force kneading method, or a ball mill crushing method is preferable. For example, the fibers can be defibrated by passing through the gaps of the rubbing media (for example, beads). The fibers can also be defibrated by sandwiching them with a stone mill rotating at high speed.

As a third method for producing CNF powder, an electric method such as an electric field spinning method can be mentioned. For example, a solution in which fibers are dissolved is put into a syringe, and a metal plate (collector electrode) is placed so as to face the needle tip of the syringe. Then, when a high voltage is applied between the needle tip of the syringe and the metal plate, the solution flies from the needle tip of the syringe toward the metal plate, and needle-shaped nanocellulose particles adhere to the metal plate. The solvent in the solution volatilizes during flight, leaving only acicular nanocellulose particles on the metal plate.

As a fourth method for producing CNF powder, a biological method using a microorganism can be mentioned. For example, acetobacter secretes cellulose fibers to form cellulose gels (pelicles). If acetobacter is used, a ribbon-like fiber of cellulose can be produced. Further, by utilizing enzymatic decomposition, it becomes possible to make cellulose fibers finer.

As a method for obtaining the CNF powder having the particle width and the particle length defined in the above-mentioned basic configuration, a method combining a TEMPO-catalyzed oxidation method and a ball mill pulverization method is particularly preferable. Specifically, the CNF powder obtained by the TEMPO-catalyzed oxidation method is finely pulverized by the ball mill pulverization method to obtain a CNF powder having the particle width and particle length specified in the above-mentioned basic configuration. The particle width of the CNF powder can be easily controlled based on the amount of TEMPO used. Specifically, as the amount of TEMPO used increases, the width of the needle-shaped nanocellulose particles tends to become smaller. In addition, the particle length of the CNF powder can be easily controlled based on the amount of media and the processing time in ball mill pulverization. Specifically, the longer the amount of media and the longer the treatment time (crushing time), the shorter the length of the needle-shaped nanocellulose particles tends to be.

The toner core can be produced, for example, by a pulverization method or an agglutination method. In these methods, the internal additive is easily dispersed in the binder resin of the toner core.

In one example of the pulverization method, first, a binder resin, a colorant, a charge control agent, and a mold release agent are mixed. Subsequently, the obtained mixture is melt-kneaded using a melt-kneading device (for example, a single-screw or twin-screw extruder). Subsequently, the obtained melt-kneaded product is crushed, and the obtained crushed product is classified. As a result, a toner core having a desired particle size can be obtained.

In one example of the agglutination method, first, these fine particles are aggregated to a desired particle size in an aqueous medium containing fine particles of each of the binder resin, the mold release agent, and the colorant. As a result, agglomerated particles containing a binder resin, a mold release agent, and a colorant are formed. Subsequently, the obtained agglomerated particles are heated to coalesce the components contained in the agglomerated particles. As a result, a toner core having a desired particle size can be obtained.

By stirring the toner core powder and the nanocellulose powder obtained as described above together, a plurality of nanocellulose particles can be attached to the surface of the toner core. As a mixing device for stirring the toner core powder and the nanocellulose powder together, an FM mixer manufactured by Nippon Coke Industries Co., Ltd., a multipurpose mixer manufactured by Nippon Coke Industries Co., Ltd., or Now manufactured by Hosokawa Micron Co., Ltd. A tar mixer (registered trademark) can be used. A composite core can be obtained by adhering a plurality of nanocellulose particles to the surface of the toner core. In order to obtain a toner suitable for image formation, it is preferable that the nanocellulose particles are uniformly dispersed on the surface of the toner core. However, if the length of the nanocellulose particles is too long, it becomes difficult for the nanocellulose particles to be uniformly dispersed.

The method of forming the shell layer is arbitrary. For example, a shell layer can be formed on the surface of the toner core by an in-situ polymerization method, a submerged curing coating method, or a core selvation method.

In order to suppress the dissolution or elution of the toner core component (particularly, the binder resin and the release agent) at the time of forming the shell layer, it is preferable to form the shell layer in an aqueous medium. The aqueous medium is a medium containing water as a main component (more specifically, pure water, a mixed solution of water and a polar medium, or the like). Further, in order to uniformly adhere the shell material to the surface of the composite core, it is preferable to highly disperse the composite core in an aqueous medium containing the shell material. The composite core has strong hydrophilicity due to the presence of nanocellulose particles and is highly easily dispersed in an aqueous medium.

In order to obtain a toner suitable for image formation, _{it is preferable that the volume median diameter (D 50} ) of the toner is 4 μm or more and 9 μm or less.

Hereinafter, a preferable example of the composition of the toner particles will be described. The toner core contains a binder resin. If necessary, the toner core may contain an internal additive (for example, at least one of a release agent, a colorant, a charge control agent, and a magnetic powder) in addition to the binder resin.

[Toner core]
(Bundling resin)
Generally, the binder resin is the main component of the toner. In a preferred example of a magnetic toner containing magnetic powder, the binder resin occupies about 60% by mass of the toner core. In a preferred example of a non-magnetic toner containing no magnetic powder, the binder resin occupies about 85% by mass of the toner core. Therefore, it is considered that the properties of the binder resin have a great influence on the properties of the entire toner core. By using a plurality of types of resins in combination as the binder resin, the properties of the binder resin (more specifically, hydroxyl value, acid value, Tg, Tm, etc.) can be adjusted. When the binder resin has an ester group, a hydroxyl group, an ether group, an acid group, or a methyl group, the toner core tends to be anionic, and when the binder resin has an amino group, the toner core has a cation. The tendency to become sexual becomes stronger.

As the binder resin, a polyester resin is preferable, and a polyester resin having a glass transition point (Tg) of 40 ° C. or higher and 60 ° C. or lower and a softening point (Tm) of 70 ° C. or higher and 110 ° C. or lower is particularly preferable.

The polyester resin is obtained by polycondensing one or more kinds of polyhydric alcohols and one or more kinds of polyvalent carboxylic acids. As the alcohol for synthesizing the polyester resin, for example, a divalent alcohol (more specifically, an aliphatic diol, a bisphenol, etc.) or a trihydric or higher alcohol as shown below can be preferably used. As the carboxylic acid for synthesizing the polyester resin, for example, a divalent carboxylic acid or a trivalent or higher carboxylic acid as shown below can be preferably used.

Preferable examples of aliphatic diols are diethylene glycol, triethylene glycol, neopentyl glycol, 1,2-propanediol, α, ω-alkanediol (more specifically, ethylene glycol, 1,3-propanediol). , 1,4-Butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, or 1,12-dodecanediol. Etc.), 2-butene-1,4-diol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol.

Preferable examples of bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, or bisphenol A propylene oxide adduct.

Preferable examples of trihydric or higher alcohols are sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolethane, or 1,3,5- Trihydroxymethylbenzene can be mentioned.

Preferable examples of the divalent carboxylic acid include aromatic dicarboxylic acids (more specifically, phthalic acid, terephthalic acid, isophthalic acid, etc.), α, ω-alcandicarboxylic acids (more specifically, malonic acid). , Succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, or 1,10-decandicarboxylic acid, etc.), alkylsuccinic acid (more specifically, n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, etc.) Acid, n-dodecyl succinic acid, or isododecyl succinic acid, etc.), alkenyl succinic acid (more specifically, n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, or isodode (Senyl succinic acid, etc.), maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, or cyclohexanedicarboxylic acid.

Preferable examples of trivalent or higher valent carboxylic acids are 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1, 2,4-Butantricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Examples include methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimeric acid.

As the polyester resin (binding resin), a polyester resin containing plant-derived 1,2-propanediol as an alcohol component is preferable, and plant-derived 1,2-propanediol and one or more aromatic dicarboxylic acids (for example, A polymer of a monomer (resin raw material) containing terephthalic acid) is particularly preferable. In order to improve the low temperature fixability of the toner while ensuring sufficient environmental friendliness, it is preferable that 60% by mass or more of the alcohol component of the polyester resin (binding resin) is plant-derived 1,2-propanediol. It is particularly preferable that 100% by mass of the alcohol component of the polyester resin (binding resin) is plant-derived 1,2-propanediol.

Plant-derived 1,2-propanediols can be produced, for example, by using chemical synthesis, fermentation methods, or a combination of these methods. In one example of a method for producing a plant-derived 1,2-propanediol, glycerin is obtained by hydrolyzing plant biomass containing saccharides such as glucose. Subsequently, a plant-derived 1,2-propanediol is obtained by reacting glycerin with hydrogen. As the vegetable biomass, for example, one or more vegetable oils and fats selected from the group consisting of soybean oil, palm oil, palm oil, castor oil, and coconut oil can be used. As a method for hydrolyzing plant biomass, a chemical method using an acid or a base may be adopted, a biological method using an enzyme or a microorganism may be adopted, or another method may be adopted. May be good.

As a method for synthesizing a polyester resin, in the presence of a catalyst, under conditions of a temperature of 200 ° C. or higher and 250 ° C. or lower, one or more polyhydric alcohols and one or more polyvalent carboxylic acids are used while removing volatile components produced as by-products. There is a method of polycondensing. In order to accelerate the polymerization reaction, the polymerization reaction of the resin raw material (monomer or prepolymer) may be carried out in a reduced pressure atmosphere. Examples of catalysts include metals (more specifically tin, titanium, antimony, manganese, nickel, zinc, lead, iron, magnesium, calcium, germanium, etc.) or metal compounds (more specifically, as described above). Metal oxides, etc.).

Further, the toner core may contain a resin other than the polyester resin as the binder resin. Examples of the binder resin other than the polyester resin include a styrene resin, an acrylic acid resin (more specifically, an acrylic acid ester polymer or a methacrylic acid ester polymer, etc.), and an olefin resin (more specifically). , Polyethylene resin, polypropylene resin, etc.), vinyl chloride resin, polyvinyl alcohol, vinyl ether resin, N-vinyl resin, polyamide resin, or thermoplastic resin such as urethane resin is preferable. Further, a copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the above resin (more specifically, a styrene-acrylic acid-based resin, a styrene-butadiene-based resin, or the like) is also formed. It can be suitably used as a resin coating.

(Colorant)
The toner core may contain a colorant. As the colorant, a pigment or dye known according to the color of the toner can be used. In order to obtain a toner suitable for image formation, the amount of the colorant is preferably 0.1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin.

The toner core may contain a black colorant. An example of a black colorant is carbon black. Further, the black colorant may be a colorant that has been adjusted to black by using a yellow colorant, a magenta colorant, and a cyan colorant. As the black colorant, a magnetic powder described later may be used.

Toner cores include yellow colorants (more specifically, naphthol yellow, monoazo yellow, diazo yellow, disazo yellow, or anthraquinone compounds, etc.), magenta colorants (more specifically, quinacridone compounds, naphthol compounds, carmine 6B, etc.). Alternatively, it may contain a color colorant such as monoazored, etc.) or a cyan colorant (more specifically, phthalocyanine blue, anthraquinone compound, etc.).

(Release agent)
The toner core may contain a release agent. The release agent is used, for example, for the purpose of improving the fixability or offset resistance of the toner. In order to improve the fixability or offset resistance of the toner, the amount of the release agent is preferably 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin.

Wax is preferable as the release agent in the toner core. Examples of waxes include ester waxes, polyethylene waxes, polypropylene waxes, fluororesin waxes, Fishertroph waxes, paraffin waxes, or Montan waxes. Ester wax is preferable in order to improve the fixability and offset resistance of the toner. Examples of the ester wax include natural ester wax (for example, carnauba wax or rice wax), or synthetic ester wax. In the toner having the above-mentioned basic configuration, when the toner core contains a polyester resin as a binder resin, the toner core may contain an ester wax (for example, carnauba wax) or a polyethylene wax as a release agent. Especially preferable. One type of release agent may be used alone, or a plurality of types of release agents may be used in combination.

(Charge control agent)
The toner core may contain a charge control agent. The charge control agent is used, for example, for the purpose of improving the charge stability or charge rise characteristics of the toner. The charge rising characteristic of the toner is an index of whether or not the toner can be charged to a predetermined charge level in a short time.

By incorporating a negatively charged charge control agent (more specifically, an organometallic complex, a chelate compound, etc.) in the toner core, the anionic property of the toner core can be strengthened. Further, by incorporating a positively charged charge control agent (more specifically, pyridine, niglosin, quaternary ammonium salt, etc.) in the toner core, the cationic property of the toner core can be strengthened. However, it is not necessary to include a charge control agent in the toner core when sufficient chargeability is ensured in the toner.

(Magnetic powder)
The toner core may contain magnetic powder. Examples of the material of the magnetic powder include a ferromagnetic metal (more specifically, iron, cobalt, nickel, or an alloy containing one or more of these metals), and a ferromagnetic metal oxide (more specifically, Ferromagnetism, magnetite, chromium dioxide, etc.) or a material that has been subjected to a ferromagnetization treatment (more specifically, a carbon material to which ferromagnetism has been imparted by heat treatment, etc.) can be preferably used. One kind of magnetic powder may be used alone, or a plurality of kinds of magnetic powder may be used in combination.

In order to uniformly impart sufficient magnetism to the toner core, the particle size of the magnetic powder is preferably 0.1 μm or more and 1.0 μm or less. Further, in order to suppress the elution of metal ions (for example, iron ions) from the magnetic powder, a surface treatment agent (more specifically, a silane coupling agent, a titanate coupling agent, etc.) is used as the magnetic powder (specifically, the magnetic powder). , The surface of each magnetic particle contained in the magnetic powder) is preferably treated.

[Nanocellulose particles]
In the toner having the above-mentioned basic configuration, the toner particles include a composite core and a shell layer covering the surface of the composite core. The composite core is a composite of a toner core and a plurality of nanocellulose particles. Each of the plurality of nanocellulose particles is attached to the surface of the toner core. As the nanocellulose particles, cellulose nanofiber particles and / or cellulose nanocrystal particles are particularly preferable. The cellulose nanofiber particles and the cellulose nanocrystal particles may be surface-treated (for example, hydrophobized), respectively.

[Shell layer]
The shell layer contains a copolymer of one or more vinyl compounds represented by the above formula (1) and one or more other vinyl compounds (that is, vinyl compounds other than compound (1)). Is preferable.

It is particularly preferable that the shell layer contains a copolymer of a monomer (resin raw material) containing one or more compounds (1) and one or more (meth) acrylic acid alkyl esters. As a material for forming the shell layer, for example, an oxazoline group-containing polymer aqueous solution (“Epocross (registered trademark) WS series” manufactured by Nippon Shokubai Co., Ltd.) can be used. "Epocross WS-300" and "Epocross WS-700" each contain a polymer of a monomer (resin raw material) containing 2-vinyl-2-oxazoline and one or more (meth) acrylic acid alkyl esters. ..

As the other vinyl compound, one or more vinyl compounds selected from the group consisting of styrene-based monomers and acrylic acid-based monomers are preferable. Preferable examples of the styrene-based monomer include styrene, alkyl styrene (more specifically, α-methyl styrene, p-ethyl styrene, 4-tert-butyl styrene, etc.), and hydroxy styrene (more specifically, styrene-based monomer). (P-Hydroxystyrene, m-hydroxystyrene, etc.), or halogenated styrene (more specifically, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) can be mentioned. Preferable examples of the acrylic acid-based monomer include (meth) acrylic acid, (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl ester, (meth) acrylic acid aryl ester, (meth) acrylonitrile, or Examples include (meth) acrylamide.

For example, when another vinyl compound is an acrylic acid alkyl ester in which an alkyl group may have a substituent, the acrylic acid alkyl ester is a repeating unit represented by, for example, the following formula (2) by addition polymerization. To form a copolymer.

In formula (2), R ² represents an alkyl group (which may be linear, branched, or cyclic) which may have a substituent. As the alkyl group, an alkyl group having 1 or more carbon atoms and 8 or less carbon atoms is preferable. When R ² represents an alkyl group having a substituent, a hydroxyl group is preferable as the substituent of the alkyl group. As R ² , a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a 2-ethylhexyl group, a hydroxyethyl group, a hydroxypropyl group, or a hydroxybutyl group is preferable. ..

For example, when the other vinyl compound is a methacrylic acid alkyl ester which may have a substituent, the methacrylic acid alkyl ester which may have a substituent is represented by, for example, the following formula (3) by addition polymerization. It becomes a repeating unit to form a copolymer.

In formula (3), R ³ represents an alkyl group (which may be linear, branched, or cyclic) which may have a substituent. As the alkyl group, an alkyl group having 1 or more carbon atoms and 8 or less carbon atoms is preferable. When R ³ represents an alkyl group having a substituent, a hydroxyl group is preferable as the substituent of the alkyl group. As R ³ , a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a 2-ethylhexyl group, a hydroxyethyl group, a hydroxypropyl group, or a hydroxybutyl group is preferable. ..

For example, when the other vinyl compound is a styrene-based monomer, the styrene-based monomer forms a copolymer by addition polymerization, for example, in a repeating unit represented by the following formula (4).

In formula (4), R ^{41 to} R ⁴⁷ each independently represent a hydrogen atom or an arbitrary substituent. As R ^{41 to} R ⁴⁵ , an alkyl group which may have a halogen atom, a hydroxyl group and a substituent, or an aryl group which may have a substituent is preferable, respectively, and a halogen atom, a methyl group and an ethyl are preferable. Groups or hydroxyl groups are particularly preferred. As R ⁴⁶ and R ⁴⁷ , hydrogen atoms or methyl groups are preferable independently of each other.

[External agent]
An external additive (specifically, a powder containing a plurality of external additive particles) may be attached to the surface of the toner matrix particles. Unlike the internal additive, the external additive does not exist inside the toner matrix particles, but selectively exists only on the surface of the toner matrix particles (the surface layer portion of the toner particles). For example, by stirring the toner matrix particles (powder) and the external additive (powder) together, the external additive particles can be adhered to the surface of the toner matrix particles. The toner mother particles and the external additive particles do not chemically react with each other and are physically bonded rather than chemically. The strength of the bond between the toner mother particles and the external additive particles is determined by the stirring conditions (more specifically, the stirring time, the rotation speed of stirring, etc.), the particle size of the external additive particles, and the shape of the external additive particles. , And the surface condition of the external additive particles can be adjusted.

As the external additive particles, inorganic particles are preferable, and silica particles or particles of metal oxides (more specifically, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, etc.) are preferable. Especially preferable. However, as the external additive particles, particles of an organic acid compound such as a fatty acid metal salt (more specifically, zinc stearate or the like) or resin particles may be used. Further, as the external additive particles, composite particles which are composites of a plurality of kinds of materials may be used. One type of external additive particles may be used alone, or a plurality of types of external agent particles may be used in combination.

In order to improve the fluidity of the toner, it is preferable to use silica particles. In order to improve the polishability of the toner, it is preferable to use titanium oxide particles. For example, in order to improve the chargeability of the toner, it is preferable that the external additive present on the surface of the toner mother particles contains silica particles and titanium oxide particles. By using silica particles with high electrical resistance and titanium oxide particles with low electrical resistance together as an external additive, the generated electric charges are generated by the silica particles over the entire surface of the toner particles. It becomes possible to disperse evenly.

The external additive particles may be surface-treated. For example, when silica particles are used as the external additive particles, the surface of the silica particles may be imparted with hydrophobicity and / or positive chargeability by a surface treatment agent. Examples of the surface treatment agent include a coupling agent (more specifically, a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, etc.), a silazane compound (for example, a chain silazane compound or a cyclic silazane compound). ) Or silicone oil (more specifically, dimethyl silicone oil or the like) can be preferably used. As the surface treatment agent, a silane coupling agent or a silazane compound is particularly preferable. Preferable examples of the silane coupling agent include silane compounds (more specifically, methyltrimethoxysilane, aminosilane, etc.). Preferable examples of the silazane compound include HMDS (hexamethyldisilazane).

When the surface of the silica substrate (untreated silica particles) is treated with a surface treatment agent, a large number of hydroxyl groups (-OH) present on the surface of the silica substrate are partially or wholly derived from the surface treatment agent. Substituted for a functional group. As a result, silica particles having a functional group derived from the surface treatment agent (specifically, a functional group having a more hydrophobic and / or positively charged property than a hydroxyl group) on the surface can be obtained. For example, when the surface of a silica substrate is treated with a silane coupling agent having an amino group, the hydroxyl group of the silane coupling agent (for example, the hydroxyl group generated by hydrolyzing the alkoxy group of the silane coupling agent with water) is generated. A dehydration condensation reaction (“A (silica substrate) -OH” + “B (coupling agent) -OH” → “A—OB” + H ₂ O) with a hydroxyl group existing on the surface of the silica substrate. By such a reaction, the silane coupling agent having an amino group and silica are chemically bonded to impart an amino group to the surface of the silica particles, and positively charged silica particles are obtained. More specifically, the hydroxyl group existing on the surface of the silica substrate is replaced with a functional group having an amino group at the end (more specifically, -O-Si- (CH ₂ ) _3- NH _2, etc.). Silica particles to which an amino group is added tend to have a stronger positive charge property than a silica substrate. Further, when a silane coupling agent having an alkyl group is used, hydrophobic silica particles can be obtained. More specifically, the hydroxyl group existing on the surface of the silica substrate can be replaced with a functional group having an alkyl group at the end (more specifically, -O-Si-CH _3, etc.) by the dehydration condensation reaction. it can. As described above, the silica particles to which the hydrophobic group (alkyl group) is added instead of the hydrophilic group (hydroxyl group) tend to have stronger hydrophobicity than the silica substrate.

As the external additive particles, external additive particles provided with a conductive layer may be used. The conductive layer is, for example, a layer of a metal oxide (hereinafter, referred to as a doping metal oxide) to which conductivity has been imparted by doping (more specifically, an Sb-doped SnO ₂ layer or the like). Further, the conductive layer may be a layer containing a conductive material (more specifically, a metal, a carbon material, a conductive polymer, etc.) other than the doping metal oxide.

Examples of the present invention will be described. Table 1 shows the toners TA-1 to TA-5 and TB-1 to TB-8 (toners for electrostatic latent image development, respectively) according to Examples or Comparative Examples.

Hereinafter, the manufacturing method, the evaluation method, and the evaluation result of the toners TA-1 to TA-5 and TB-1 to TB-8 will be described in order. In the evaluation in which an error occurs, a considerable number of measured values in which the error is sufficiently small are obtained, and the arithmetic mean of the obtained measured values is used as the evaluation value.

[Preparation of materials]
(Method for producing CNF powder C-1)
1.5 L of ion-exchanged water was placed in a container (first container). Then, 200 parts by mass of sulfurous acid bleached softwood pulp equivalent to 200 parts by mass in dry mass, 1.5 parts by mass of TEMPO (2,2,6,6-TEtraMetyl Piperidine-1-Oxyradical), and 25 parts by mass of sodium bromide were placed in a container. In addition, it was dispersed in water. Subsequently, an aqueous solution of sodium hypochlorite having a concentration of 13% by mass was added into the container so that the amount of sodium hypochlorite per 1 g of pulp in the container was 1.5 mmol, and the contents of the container were reacted. I let you. During the reaction, while checking the pH of the contents of the container, an aqueous sodium hydroxide solution having a molar concentration of 0.5 M was added dropwise into the container according to the amount of change in pH to maintain the pH of the contents of the container at 10.5. .. It is judged that the reaction is completed when the pH of the container contents does not change, and the container contents containing the reaction product are solid-liquid separated (filtered) using a glass filter to form a solid product (reaction product). ) Was obtained. Then, the obtained solid matter was redispersed in a sufficient amount of ion-exchanged water and washed with water. Dispersion and filtration were repeated 5 times in total. As a result, a water-impregnated fiber body (solid content concentration: 25% by mass) was obtained.

Subsequently, the obtained water-impregnated fiber body and ion-exchanged water were placed in a container (second container) different from the first container to prepare a slurry having a solid content concentration of 2% by mass. .. Subsequently, the container contents (slurry) were subjected to dispersion treatment using a rotary blade type mixer. The dispersion treatment increased the viscosity of the container contents (slurry). During the dispersion treatment, ion-exchanged water is added into the container so as to keep the viscosity of the container contents (slurry) substantially constant, and when the solid content concentration of the container contents (slurry) reaches 0.15% by mass. The distributed processing was completed at. As a result, a dispersion liquid containing a cellulose fiber body (solid content concentration: 0.15% by mass) was obtained. The dispersion processing time was about 5 minutes.

Subsequently, the obtained dispersion was separated into suspended matter and sediment by centrifugation, and the suspended matter was removed. Subsequently, the sediment was washed with water and then dried to obtain a dried cellulose fiber body. Subsequently, by crushing the dried cellulose fiber body, CNF powder C-1 (cellulose nanofiber particle powder) having a particle width (number average fiber diameter) of 30 nm and a particle length (number average fiber length) of 1500 nm. ) Was obtained.

(Method for producing CNF powder C-2)
20 g of CNF powder C-1 obtained as described above, 500 g of zirconia beads having a diameter of 0.1 mm, and a capacity of 1 L were placed in a polyethylene container, and the container was set in a ball mill. Then, using the ball mill, the contents of the container were pulverized for 2 hours under the condition of a rotation speed of 100 rpm. As a result, CNF powder C-1 was pulverized by pulverized media (zirconia beads) to obtain finer CNF powder C-2 (powder of cellulose nanofiber particles). By pulverizing the media, the particle length of the CNF powder C-2 became shorter than the particle length of the CNF powder C-1.

(Method for producing CNF powder C-3)
The method for producing CNF powder C-3 was the same as the method for producing CNF powder C-2, except that the pulverization treatment time was changed from 2 hours to 4 hours. By lengthening the pulverization treatment time, the particle length of the CNF powder C-3 became shorter than the particle length of the CNF powder C-2.

(Method for producing CNF powder C-4)
20 g of CNF powder C-1 obtained in the above procedure, 1500 g of zirconia beads having a diameter of 0.1 mm, and a capacity of 1 L were placed in a polyethylene container, and the container was set in a ball mill. Then, using the ball mill, the contents of the container were pulverized for 10 hours under the condition of a rotation speed of 100 rpm. As a result, CNF powder C-1 was pulverized by pulverized media (zirconia beads) to obtain finer CNF powder C-4 (powder of cellulose nanofiber particles). Compared with the method for producing CNF powder C-3, the amount of crushed media was increased and the media was crushed over a longer period of time, so that the particle length of CNF powder C-4 became CNF powder. It became shorter than the particle length of C-3.

(Method for producing CNF powder C-5)
The method for producing CNF powder C-5 was the same as the method for producing CNF powder C-1, except that the amount of TEMPO used was changed from 1.50 parts by mass to 1.75 parts by mass. By increasing the amount of TEMPO used, the particle width of CNF powder C-5 became smaller than the particle width of CNF powder C-1.

(Method for producing CNF powder C-6)
20 g of CNF powder C-5 obtained as described above, 500 g of zirconia beads having a diameter of 0.1 mm, and a capacity of 1 L were placed in a polyethylene container, and the container was set in a ball mill. Then, using the ball mill, the contents of the container were pulverized for 4 hours under the condition of a rotation speed of 100 rpm. As a result, CNF powder C-5 was pulverized by pulverized media (zirconia beads) to obtain finer CNF powder C-6 (powder of cellulose nanofiber particles). By pulverizing the media, the particle length of the CNF powder C-6 became shorter than the particle length of the CNF powder C-5.

(Method for producing CNF powder C-7)
The method for producing CNF powder C-7 was the same as the method for producing CNF powder C-1, except that the amount of TEMPO used was changed from 1.5 parts by mass to 2.0 parts by mass. By increasing the amount of TEMPO used, the particle width of CNF powder C-7 became smaller than the particle width of CNF powder C-5.

(Method for producing CNF powder C-8)
20 g of CNF powder C-7 obtained as described above, 500 g of zirconia beads having a diameter of 0.1 mm, and a capacity of 1 L were placed in a polyethylene container, and the container was set in a ball mill. Then, using the ball mill, the contents of the container were pulverized for 4 hours under the condition of a rotation speed of 100 rpm. As a result, CNF powder C-7 was pulverized by pulverized media (zirconia beads) to obtain finer CNF powder C-8 (powder of cellulose nanofiber particles). By pulverizing the media, the particle length of the CNF powder C-8 became shorter than the particle length of the CNF powder C-7.

(Method for producing CNF powder C-9)
The method for producing CNF powder C-9 was the same as the method for producing CNF powder C-1, except that the amount of TEMPO used was changed from 1.5 parts by mass to 1.1 parts by mass. By reducing the amount of TEMPO used, the particle width of CNF powder C-9 became larger than the particle width of CNF powder C-1.

(Method for producing CNF powder C-10)
20 g of CNF powder C-9 obtained as described above, 500 g of zirconia beads having a diameter of 0.1 mm, and a capacity of 1 L were placed in a polyethylene container, and the container was set in a ball mill. Then, using the ball mill, the contents of the container were pulverized for 4 hours under the condition of a rotation speed of 100 rpm. As a result, CNF powder C-9 was pulverized by pulverized media (zirconia beads) to obtain finer CNF powder C-10 (powder of cellulose nanofiber particles). By pulverizing the media, the particle length of the CNF powder C-10 became shorter than the particle length of the CNF powder C-9.

(Method for producing CNF powder C-11)
The method for producing CNF powder C-11 was the same as the method for producing CNF powder C-1, except that the amount of TEMPO used was changed from 1.5 parts by mass to 0.7 parts by mass. By reducing the amount of TEMPO used, the particle width of CNF powder C-11 became larger than the particle width of CNF powder C-9.

(Method for producing CNF powder C-12)
20 g of CNF powder C-11 obtained as described above, 500 g of zirconia beads having a diameter of 0.1 mm, and a capacity of 1 L were placed in a polyethylene container, and the container was set in a ball mill. Then, using the ball mill, the contents of the container were pulverized for 4 hours under the condition of a rotation speed of 100 rpm. As a result, CNF powder C-11 was pulverized by pulverized media (zirconia beads) to obtain finer CNF powder C-12 (powder of cellulose nanofiber particles). By pulverizing the media, the particle length of the CNF powder C-12 became shorter than the particle length of the CNF powder C-11.

(Method for producing CNF powder C-13)
The method for producing CNF powder C-13 was the same as the method for producing CNF powder C-12, except that the pulverization treatment time was changed from 4 hours to 10 hours. By lengthening the pulverization treatment time, the particle length of the CNF powder C-13 became shorter than the particle length of the CNF powder C-12.

[Manufacturing method of toners TA-1 to TA-5 and TB-1 to TB-8]
(Making a toner core)
A reaction vessel having a capacity of 5 L equipped with a thermometer (thermocouple), a dehydration tube, a nitrogen introduction tube, a rectification tower, and a stirrer was set in an oil bath, and a plant-derived 1,2-propanediol was placed in the vessel. 1200 g, 1700 g of terephthalic acid, and 3 g of an esterification catalyst (tin (II) 2-ethylhexanoate) were added. Subsequently, the temperature inside the container was raised to 230 ° C. using an oil bath, and the contents of the container were reacted for 15 hours (specifically, a condensation reaction) under the conditions of a nitrogen atmosphere and a temperature of 230 ° C. Subsequently, the inside of the container is depressurized, and the contents of the container are kept under the conditions of a reduced pressure atmosphere (pressure 8.0 kPa) and a temperature of 230 ° C. until the Tm of the reaction product (polyester resin) reaches a predetermined temperature (90 ° C.). It was reacted. As a result, a polyester resin having a Tm of 90 ° C. was obtained.

80 parts by mass of the binder resin (polyester resin obtained as described above) and 9 mass of mold release agent (ester wax having a melting point of 73 ° C.: "Nissan Electol (registered trademark) WEP-3" manufactured by Nippon Oil Co., Ltd.) The parts and 9 parts by mass of carbon black (“MA100” manufactured by Mitsubishi Chemical Corporation) were mixed for 4 minutes under the condition of a rotation speed of 2000 rpm using an FM mixer (“FM-20B” manufactured by Nippon Coke Industries Co., Ltd.).

Subsequently, the obtained mixture was subjected to the conditions of a shaft rotation speed of 150 rpm, a set temperature range (cylinder temperature) of 100 ° C., and a processing speed of 100 g / min using a twin-screw extruder (“PCM-30” manufactured by Ikegai Co., Ltd.). It was melt-kneaded in. Subsequently, the obtained melt-kneaded product was cooled. Subsequently, the cooled melt-kneaded product was roughly pulverized using a pulverizer (“Rotoplex (registered trademark)” manufactured by Hosokawa Micron Co., Ltd.) under the condition of a set particle size of 2 mm. Further, the obtained coarsely pulverized product was finely pulverized using a pulverizer (“Turbo Mill RS type” manufactured by Freund Turbo Co., Ltd.). Subsequently, the obtained finely pulverized product was classified using a classification machine (“Elbow Jet EJ-LABO type” manufactured by Nittetsu Mining Co., Ltd.). As a result, a toner core having a medium volume diameter (D ₅₀ ) of 6.7 μm, Tm 90 ° C., and Tg 49 ° C. was obtained.

(Core external)
Using an FM mixer (“FM-10C” manufactured by Nippon Coke Industries Co., Ltd.), 100 parts by mass of the toner core obtained as described above and the CNF powders of the types shown in Table 1 (CNF powder specified for each toner). 1.5 parts by mass (any of the bodies C-1 to C-13) was mixed for 5 minutes. For example, in the production of the toner TA-1, CNF powder C-3 was used.

The external addition process at this timing (specifically, the mixture of the toner core and the CNF powder) corresponds to the “core external addition”. CNF particles adhered to the surface of the toner core due to core external addition. As a result, a composite core (specifically, a toner core in which CNF particles are attached to the surface) was obtained.

(Shell layer forming process)
A 1 L capacity three-necked flask equipped with a thermometer and a stirring blade was set in a water bath, and 300 g of ion-exchanged water was placed in the flask. Then, the temperature inside the flask was kept at 30 ° C. using a water bath. Subsequently, 30 g of an oxazoline group-containing polymer aqueous solution (“Epocross WS-300” manufactured by Nippon Catalyst Co., Ltd., solid content concentration: 10% by mass) was added into the flask, and then the contents of the flask were sufficiently stirred.

Subsequently, 300 g of the composite core prepared by the above procedure was added to the flask, and the contents of the flask were stirred at a rotation speed of 200 rpm for 1 hour. Then, 300 g of ion-exchanged water was added into the flask.

Subsequently, 6 mL of a 1% by mass aqueous ammonia solution was added to the flask. Subsequently, the temperature inside the flask was raised to 60 ° C. at a rate of 0.5 ° C./min while stirring the contents of the flask at a rotation speed of 150 rpm. Subsequently, the contents of the flask were kept at that temperature (60 ° C.) for 1 hour while stirring the contents of the flask at a rotation speed of 100 rpm. As a result, a shell layer having a thickness of about 5 nm was formed on the surface of the composite core.

Subsequently, a 1% by mass aqueous ammonia solution was added to the flask to adjust the pH of the contents of the flask to 7. Subsequently, the contents of the flask were cooled until the temperature reached room temperature (about 25 ° C.) to obtain a dispersion liquid containing toner matrix particles.

(Washing process)
The dispersion liquid of the toner mother particles obtained as described above was filtered (solid-liquid separation) using a Büchner funnel to obtain a wet cake-shaped toner mother particles. Then, the obtained wet cake-like toner matrix particles were redispersed in ion-exchanged water. Further, dispersion and filtration were repeated 5 times to wash the toner matrix particles.

(Drying process)
Subsequently, the obtained toner mother particles were dispersed in an aqueous ethanol solution having a concentration of 50% by mass. As a result, a slurry of toner mother particles was obtained. Subsequently, using a continuous surface modifier (“Coatmizer (registered trademark)” manufactured by Freund Sangyo Co., Ltd.), the toner matrix particles in the slurry were removed under the conditions of a ^{hot air temperature of 45 ° C. and a blower air volume of 2 m 3 / min.} It was dried. As a result, a powder of toner mother particles was obtained.

(Shell external)
Subsequently, using an FM mixer (“FM-10C” manufactured by Nippon Coke Industries Co., Ltd.), 100 parts by mass of the toner mother particles obtained as described above and positively charged silica particles (“AEROSIL” manufactured by Nippon Aerosil Co., Ltd.) (Registered Trademark) REA90 ”, Contents: Dry silica particles imparted with positive charge by surface treatment, number average primary particle diameter: 20 nm) 1.5 parts by mass, and conductive titanium oxide particles (manufactured by Titanium Industry Co., Ltd.) "EC-100", substrate: TiO ₂ particles, coating layer: Sb-doped SnO ₂ , medium volume diameter: about 0.35 μm) 1.5 parts by mass were mixed for 5 minutes. The external addition treatment at this timing (specifically, the mixture of the toner mother particles and the external additive) corresponds to "shell external addition". By shell external addition, an external additive (specifically, silica particles and titanium oxide particles) adhered to the surface of the toner matrix particles. Then, sieving was performed using a sieve of 200 mesh (opening 75 μm). As a result, toners containing a large number of toner particles (toners TA-1 to TA-5 and TB-1 to TB-8) were obtained.

The results of measuring the particle width and particle length of the CNF powder with respect to the toners TA-1 to TA-5 and TB-1 to TB-8 obtained as described above are as shown in Table 1. .. “Particle width” and “particle length” in Table 1 indicate numerical average values (unit: nm), respectively. Image analysis software (Mitani Shoji Co., Ltd.) captures the SEM image obtained by photographing the surface of toner particles using a field emission scanning electron microscope (FE-SEM) (“JSM-7600F” manufactured by Nippon Denshi Co., Ltd.). The particle width and particle length of the CNF powder present on the surface of the toner mother particles were measured by analysis using "WinROOF" manufactured by M.E., Ltd., respectively. For example, in the toner TA-1, in the CNF powder existing on the surface of the toner mother particles, the width of the CNF particles was 29 nm on a numerical average, and the length of the CNF particles was 300 nm on a numerical average.

[Evaluation method]
The evaluation method of each sample (toner TA-1 to TA-5 and TB-1 to TB-8) is as follows.

(Shell coated state)
Regarding the toner particles contained in the toner (evaluation target: any of toners TA-1 to TA-5 and TB-1 to TB-8), a field emission scanning electron microscope (FE-SEM) (manufactured by JEOL Ltd.) The coating state of the shell layer was confirmed using "JSM-7600F").

The coating condition of the shell layer was evaluated according to the following criteria.
◯ (Good): The shell layer covered the nanocellulose particles existing on the surface of the toner core, so that the shell layer was deformed convexly at the position where the nanocellulose particles were present.
X (bad): The shell layer did not sufficiently cover the nanocellulose particles existing on the surface of the toner core, and the nanocellulose particles were partially exposed from the shell layer.

(Preparation of developer for evaluation)
Using a ball mill, 100 parts by mass of a carrier for a developing agent (carrier for "TASKalfa5551ci") and 5 parts by mass of a toner (evaluation target: any of toners TA-1 to TA-5 and TB-1 to TB-8) are used. And mixed for 30 minutes to prepare an evaluation developer (two-component developer).

(Print resistance test)
As the evaluation machine, a multifunction device (“TASKalfa5551ci” manufactured by Kyocera Document Solutions Co., Ltd.) was used. The evaluation developer prepared as described above is put into the developing apparatus of the evaluation machine, and the replenishing toner (evaluation target: any of toners TA-1 to TA-5 and TB-1 to TB-8) is evaluated. It was put into the toner container of the machine.

In an environment of a temperature of 23 ° C. and a humidity of 50% RH, a printing durability test was conducted using the above-mentioned evaluation machine to continuously print 100,000 sheets of paper (A4 size plain paper) at a printing rate of 5%.

(ID maintainability)
A sample image including a solid portion and a blank portion was formed on a recording medium (evaluation paper) by using the evaluation machine at each timing before and after the printing endurance test (initial stage and after the printing endurance test). The image density (ID) of the solid portion of the image formed on the recording medium was measured using a reflection densitometer (“RD914” manufactured by X-Rite). Based on the measured image density (ID), the rate of change in image density (rate of change in ID) was determined according to the following formula.
ID change rate = 100 × | Initial ID-ID after printing resistance test | / Initial ID

The evaluation criteria of the measured ID change rate were as follows. The minimum value of the ID change rate is 0%.
◯ (good): The ID change rate was less than 20%.
X (not good): The ID change rate was 20% or more.

(Cover resistance)
After the above-mentioned printing resistance test, a sample image including a solid portion and a blank portion was printed on a recording medium (evaluation paper) using the above evaluation machine. Then, using a reflection densitometer (“SpectroEye®” manufactured by X-Rite), the blank portion of the sample image on the printed recording medium and the unprinted base paper (unprinted paper) are respectively. The reflection density was measured. Then, the fog concentration (FD) was calculated based on the following formula.
FD = (reflection density of blank area)-(reflection density of unprinted paper)

If the fog concentration (FD) was 0.010 or less, it was evaluated as ◯ (good), and if the fog concentration (FD) was more than 0.010, it was evaluated as × (not good).

[Evaluation results]
Table 2 shows the results of evaluating the shell coating state, ID retention, and fog resistance of each of the toners TA-1 to TA-5 and TB-1 to TB-8. For the toner whose evaluation result of the shell coating state was poor, the ID retention and the fog resistance were not evaluated respectively. With a toner having a poor shell coating condition, not only the heat-resistant storage stability is deteriorated, but also it becomes difficult to secure the amount of charge required for image formation. Further, with a toner having a poor shell coating state, both the shell layer and the cellulose nanofiber particles were easily separated from the toner matrix particles.

Each of the toners TA-1 to TA-5 (toners according to Examples 1 to 5) had the above-mentioned basic configuration. Specifically, each of the toners TA-1 to TA-5 contained a plurality of toner particles having a toner mother particle and an external additive adhering to the surface of the toner mother particle. The toner mother particles included a composite core and a shell layer covering the surface of the composite core. The composite core was a composite of a toner core and a plurality of nanocellulose particles (specifically, cellulose nanofiber particles) adhering to the surface of the toner core. In a plurality of nanocellulose particles (specifically, a plurality of cellulose nanofiber particles), the width of the nanocellulose particles was 20 nm or more and 50 nm or less on a number average, and the length of the nanocellulose particles was 500 nm or less on a number average (a number average of 500 nm or less). See Table 1).

As shown in Table 2, for each of the toners TA-1 to TA-5, the evaluation results of the shell coating state, ID retention, and fog resistance were good.

In each of the toners TB-1 and TB-3 to TB-6 (toners according to Comparative Examples 1 and 3 to 6), the surface of the composite core could not be properly coated with the shell layer. The reason for this is considered to be that the length of the nanocellulose particles was too long.

In the evaluation of the ID maintainability of each of the toners TB-2, TB-7, and TB-8 (toners according to Comparative Examples 2, 7, and 8), the ID after the printing endurance test was compared with the initial ID. It has become significantly smaller. In the evaluation of the toner TB-8, silica particles (external additive) were embedded in the toner mother particles by the printing resistance test.

Similar evaluation results were obtained when cellulose nanocrystal particles were used instead of the cellulose nanofiber particles as the needle-shaped nanocellulose particles. That is, in the CNC powder existing on the surface of the toner core, the toner in which the width of the cellulose nanocrystal particles is 20 nm or more and 50 nm or less on average and the length of the cellulose nanocrystal particles is 500 nm or less on average is The evaluation results of the shell coating state, ID retention, and fog resistance were better than those of the toner that did not meet these requirements (requirements related to particle width and particle length).

The toner according to the present invention can be used for forming an image in, for example, a copying machine, a printer, or a multifunction device.

11 Toner core 12 Shell layer 13 Nanocellulose particles 14 Silica particles

Claims (5)

A toner containing a plurality of toner particles including a composite core and a shell layer covering the surface of the composite core.
The composite core is a composite of a toner core and a plurality of nanocellulose particles adhering to the surface of the toner core, respectively.
Each of the plurality of nanocellulose particles is one or more types of nanocellulose particles selected from the group consisting of cellulose nanofiber particles and cellulose nanocrystal particles.
In the plurality of nano-cellulose particles, wherein the width of the nano cellulose particles is at 20nm or more 50nm or less in number average, the lengths of the nano-cellulose particles Ri der 50nm or 500nm or less the number-average, an aspect of the nano cellulose particles The ratio is a number average of 2.2 or more and 20.5 or less , toner. The toner according to claim 1, wherein the shell layer contains at least a copolymer of two or more kinds of vinyl compounds containing a compound represented by the following formula (1).

[In formula (1), R ¹ represents a hydrogen atom or an alkyl group which may have a substituent. ] The toner according to claim 2, wherein the toner core contains a polyester resin. The toner particles include a toner mother particle having the composite core and the shell layer, and an external additive adhering to the surface of the toner mother particle.
The external additive contains silica particles having an average number of primary particle diameters of 5 nm or more and 30 nm or less.
The thickness of the shell layer is 1 nm or more and 15 nm or less.
Any of claims 1 to 3 on the surface of the toner mother particles, the nanocellulose particles and the shell layer on the nanocellulose particles form a convex portion at a position where the nanocellulose particles are present. Or the toner described in item 1. The toner according to any one of claims 1 to 4, wherein the amount of the plurality of nanocellulose particles is 1.0 part by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the toner core.

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