Electrostatic charge image developing toner set, electrostatic charge image developer set, toner cartridge set, process cartridge, image forming apparatus, and image forming method

Abstract

The invention discloses an electrostatic charge image developing toner set, an electrostatic charge image developer set, a toner cartridge set, a process cartridge, an image forming apparatus, and an image forming method, the electrostatic charge image developing toner set having: a white toner having white toner particles containing a polyester resin and a white colorant; and a colored toner other than white color having colored toner particles containing a vinyl resin, a polyester resin, and a colored colorant, in which a mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is 0.7-10, and in which when a cross-section of the colored toner particles is observed, the mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is 0.5-10. The polyester resin forms a domain having a maximum diameter of 100 nm or more and 1 [mu] m or less.

Description

Technical Field

[0001] The present invention relates to a toner set for electrostatic charge image development, an electrostatic charge image developer set, a toner cartridge set, a process cartridge, an image forming apparatus and an image forming method. Background Art

[0002] Conventionally, it is known that in image formation by electrophotography, a white toner is used to form a colored image on a colored recording medium or a transmissive recording medium.

[0003] For example, in Japanese Patent Gazette No. 7163574, there is proposed "an image forming method, which includes the step of transferring and fixing a white colorant and at least one color of a colored colorant onto a recording medium to form an image, wherein the colored colorant has a colorant matrix particle, and the colorant matrix particle has a colorant matrix particle precursor composed of a vinyl resin and a plurality of protrusions at least arranged on the surface thereof and composed of an amorphous polyester resin."

[0004] For example, Japanese Patent Gazette No. 6123762 proposes a "toner for electrostatic image development, which is composed of toner particles containing a binder resin having a vinyl resin and an amorphous polyester resin, a colorant, and a release agent, characterized in that the toner particles are formed by dispersing an amorphous polyester resin as a domain phase in a matrix phase composed of a vinyl resin, the amorphous polyester resin being a vinyl-modified amorphous polyester resin in which a vinyl polymer segment and an amorphous polyester polymer segment are bonded, and the vinyl-modified amorphous polyester resin The content ratio of the vinyl polymer chain segment in the toner particle is 5 to 30% by mass, the number average domain diameter of the domain phase of the amorphous polyester resin is 30 to 150 nm, and when the average radius of the largest cross section in the toner particle is set to r, the total cross-sectional area a of the domain phase of the amorphous polyester resin existing in the surface region from the surface of the toner particle toward the radial inner side to a distance of r / 5 and the total cross-sectional area b of the domain phase of the amorphous polyester resin existing in the region other than the surface region satisfy the following formula (1). ".

[0005] Formula (1): a / (a+b)×100(%)≥80(%)

[0006] For example, Japanese Patent Gazette No. 2006-171139 proposes "a colorant group for electrostatic charge image development, which is composed of a yellow colorant, a cyan colorant, and a magenta colorant, characterized in that all the colorants contain at least a binding resin, a colorant, and a release agent, are coated with an external additive, have a number average particle size distribution index of less than 1.40, a volume average particle size distribution index of less than 1.30, a volume average particle size of 2.6 to 8.0 μm, and the volume average particle size of the yellow colorant is 0.4 μm to 2.0 μm larger than the volume average particle sizes of the cyan colorant and the magenta colorant." Summary of the invention

[0007] The object of the present invention is to provide a colorant group for electrostatic charge image development, which comprises: a white colorant, the white colorant having white colorant particles containing a polyester resin and a white colorant; and a colored colorant other than white, the colored colorant other than white having colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, wherein the color formation of an image having a colored image on a white image is high and peeling of the colored image is suppressed compared with the following situation: the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles is less than 0.7 or exceeds 10, or when observing the cross section of the colored colorant particles, the polyester resin forms a domain with a maximum diameter of less than 100 nm or more than 1 μm.

[0008] According to a first embodiment of the present invention, a colorant group for electrostatic charge image development is provided, comprising: a white colorant, the white colorant having white colorant particles containing a polyester resin and a white colorant; and a colored colorant other than white, the colored colorant other than white having colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, wherein a mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles is greater than or equal to 0.7 and less than or equal to 10, and when observing a cross section of the colored colorant particles, the polyester resin forms a domain having a maximum diameter of greater than or equal to 100 nm and less than or equal to 1 μm.

[0009] According to a second aspect of the present invention, in the electrostatic image developing toner set according to the first aspect, a mass ratio C of the polyester resin to the vinyl resin in the color toner particles is 2 or more and 6 or less.

[0010] According to a third aspect of the present invention, in the electrostatic image developing toner set according to the first or second aspect, when observing a cross section of the color toner particles, the polyester resin forms domains having a maximum diameter of 100 nm to 600 nm.

[0011] According to a fourth aspect of the present invention, in the electrostatic image developing toner set according to any one of the first to third aspects, the white toner particles contain a vinyl resin.

[0012] According to the fifth embodiment of the present invention, in the electrostatic charge image developing colorant group involved in the fourth embodiment, the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white colorant particles and the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles satisfies -0.6≤WC≤5.6.

[0013] According to the sixth embodiment of the present invention, in the electrostatic charge image developing colorant group involved in the fifth embodiment, the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white colorant particles and the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles satisfies 0≤WC≤4.

[0014] According to the seventh embodiment of the present invention, in the electrostatic charge image developing colorant group involved in any one of the first to sixth embodiments, when observing the cross-section of the colored colorant particles, the area ratio of the polyester resin present in the internal region of the colored colorant particles is greater than 3% and less than 25%.

[0015] According to the eighth aspect of the present invention, in the electrostatic charge image developing colorant group involved in any one of the first to seventh aspects, the white colorant particles and the colored colorant particles contain a anti-sticking agent, and the relationship between the area ratio a of the anti-sticking agent when observing the cross section of the white colorant particles and the area ratio b of the anti-sticking agent when observing the cross section of the colored colorant particles satisfies 0.03≤a / b≤0.5.

[0016] According to a ninth aspect of the present invention, in the electrostatic image developing toner set according to any one of the first to eighth aspects, a lower number size distribution index (lower GSDw) of the white toner is 1.2 or more and 1.54 or less.

[0017] According to a tenth aspect of the present invention, in the electrostatic image developing toner set according to any one of the first to ninth aspects, a lower number size distribution index (lower GSDw) of the white toner is 1.2 or more and 1.4 or less.

[0018] According to the eleventh embodiment of the present invention, in the electrostatic charge image developing colorant group involved in any one of the first to tenth embodiments, the ratio (lower GSDw / lower GSDc) of the lower number particle size distribution index (lower GSDw) of the white colorant and the lower number particle size distribution index (lower GSDc) of the colored colorant is greater than 1.0 and less than 1.4.

[0019] According to the twelfth aspect of the present invention, there is provided an electrostatic charge image developer group, comprising: a white electrostatic charge image developer, the white electrostatic charge image developer containing the white colorant possessed by the electrostatic charge image developing colorant group of any one of the first to eleventh aspects; and a colored electrostatic charge image developer, the colored electrostatic charge image developer containing the colored colorant possessed by the electrostatic charge image developing colorant group of any one of the first to eleventh aspects.

[0020] According to the thirteenth embodiment of the present invention, a colorant box group is provided, which includes: a white colorant box, which accommodates the white colorant possessed by the electrostatic charge image developing colorant group of any one of the first to eleventh embodiments, and is installed and removed from the image forming device; and a colored colorant box, which accommodates the colored colorant possessed by the electrostatic charge image developing colorant group of any one of the first to eleventh embodiments, and is installed and removed from the image forming device.

[0021] According to the fourteenth aspect of the present invention, a processing box is provided, which comprises: a first developing unit, the first developing unit accommodating the white electrostatic charge image developer included in the electrostatic charge image developer group of the twelfth aspect; and a second developing unit, the second developing unit accommodating the colored electrostatic charge image developer included in the electrostatic charge image developer group of the twelfth aspect, and the processing box is installed and removed from the image forming device.

[0022] According to the fifteenth aspect of the present invention, there is provided an image forming device comprising: a first image forming unit, the first image forming unit comprising a first developing unit containing the white electrostatic charge image developer included in the electrostatic charge image developer group of the twelfth aspect, and forming a white image based on the white colorant; a second image forming unit, the second image forming unit comprising a second developing unit containing the colored electrostatic charge image developer included in the electrostatic charge image developer group of the twelfth aspect, and forming a colored image based on the colored colorant; a transfer unit, the transfer unit transferring the white image and the colored image to the surface of a recording medium; and a fixing unit, the fixing unit fixing the white image and the colored image transferred to the surface of the recording medium.

[0023] According to the sixteenth aspect of the present invention, an image forming method is provided, which comprises: a first image forming process, forming a white image based on the white colorant contained in the electrostatic charge image developing colorant group of any one of the first to eleventh aspects; a second image forming process, forming a colored image based on the colored colorant contained in the electrostatic charge image developing colorant group of any one of the first to eleventh aspects; a transfer process, transferring the white image and the colored image to the surface of a recording medium; and a fixing process, fixing the white image and the colored image transferred to the surface of the recording medium.

[0024] (Effect)

[0025] According to the first scheme, a colorant group for electrostatic charge image development is provided, which comprises: a white colorant, the white colorant having white colorant particles containing a polyester resin and a white colorant; and a colored colorant other than white, the colored colorant other than white having colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, wherein the color formation of an image having a colored image on a white image is high and peeling of the colored image can be suppressed compared with the following situation: the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles is less than 0.7 or exceeds 10, or when observing the cross section of the colored colorant particles, the polyester resin forms a domain with a maximum diameter of less than 100 nm or more than 1 μm.

[0026] According to the second scheme, a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image and can suppress the peeling of the colored image compared to the case where the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles is less than 2 or greater than 6.

[0027] According to the third scheme, a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image, and can suppress the peeling of the colored image, compared with the case where the polyester resin forms a domain with a maximum diameter less than 100nm or greater than 600nm when observing the cross-section of the colored colorant particles.

[0028] According to the fourth aspect, a toner set for electrostatic image development is provided, which has high color formation of a color image on a white image and can suppress peeling of the color image, compared with a case where white toner particles contain only polyester resin as a binder resin.

[0029] According to the fifth scheme, a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image and can suppress peeling of the colored image, compared with a case where the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white colorant particles and the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles does not satisfy -0.6≤WC≤5.6.

[0030] According to the sixth scheme, a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image and can suppress the peeling of the colored image, compared with the case where the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white colorant particles and the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles does not satisfy 0≤WC≤4.

[0031] According to the seventh scheme, a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image and can suppress the peeling of the colored image, compared with a case where the area ratio of the polyester resin present in the internal region of the colored colorant particles is less than 3% or exceeds 25% when observing the cross-section of the colored colorant particles.

[0032] According to the eighth scheme, a colorant group for electrostatic charge image development is provided, in which the color formation of an image having a colored image on a white image is high and peeling of the colored image can be suppressed, compared with a case where the relationship between the area ratio a of the anti-sticking agent when observing the cross section of the white colorant particle and the area ratio b of the anti-sticking agent when observing the cross section of the colored colorant particle does not satisfy 0.03≤a / b≤0.5.

[0033] According to the ninth aspect, there is provided a toner set for electrostatic image development, which can suppress peeling of a white image compared with a case where the lower number size distribution index (lower GSDw) of the white toner is less than 1.2 or exceeds 1.54.

[0034] According to the tenth aspect, there is provided a toner set for electrostatic image development, which can suppress peeling of a white image compared with a case where the lower number size distribution index (lower GSDw) of the white toner is less than 1.2 or exceeds 1.4.

[0035] According to the eleventh scheme, a colorant group for developing electrostatic charge images is provided, in which the color formation of an image having a colored image on a white image is high, and peeling of the white image can be suppressed, compared with a case where the ratio (lower GSDw / lower GSDc) of the lower number particle size distribution index (lower GSDw) of the white colorant to the lower number particle size distribution index (lower GSDc) is less than 1.0 or exceeds 1.4.

[0036] According to the twelfth, thirteenth, fourteenth, fifteenth or sixteenth scheme, there is provided an electrostatic charge image developer group, a colorant box group, a processing box, an image forming apparatus, or an image forming method, which has a high color formation of an image having a colored image on a white image and can suppress the peeling of the colored image compared to the case where the following electrostatic charge image developing colorant group is applied, wherein the electrostatic charge image developing colorant group comprises: a white toner, the white toner having white toner particles containing a polyester resin and a white colorant; and a colored toner other than white, the colored toner other than white having colored toner particles containing a vinyl resin, a polyester resin and a colored colorant, wherein the mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is less than 0.7 or exceeds 10, or when observing the cross section of the colored toner particles, the polyester resin forms a domain with a maximum diameter of less than 100 nm or greater than 1 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0038] Figure 2 is a schematic structural diagram showing an example of a process cartridge according to the present embodiment;

[0039] Figure 3 This is a schematic diagram showing an example of a screw extruder used in the kneading and pulverizing method. DETAILED DESCRIPTION

[0040] The following describes embodiments of the present invention. These descriptions and examples are intended to illustrate the embodiments and do not limit the scope of the present invention.

[0041] In the present embodiment, a numerical range expressed using “to” indicates a range including the numerical values ​​described before and after “to” as the minimum value and the maximum value, respectively.

[0042] In the numerical range recorded in the present embodiment, the upper limit or lower limit recorded in one numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other segments. In addition, in the numerical range recorded in the present embodiment, the upper limit or lower limit of the numerical range can also be replaced by the value shown in the embodiment.

[0043] In the present embodiment, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0044] In this embodiment, when the embodiment is described with reference to the drawings, the structure of the embodiment is not limited to the structure shown in the drawings. In addition, the sizes of the components in each figure are conceptual, and the relative relationship between the sizes of the components is not limited to this.

[0045] In the present embodiment, each component may also include a plurality of corresponding substances. In the present embodiment, when referring to the amount of each component in the composition, when there are a plurality of substances equivalent to each component in the composition, unless otherwise specified, it refers to the total amount of the plurality of substances present in the composition.

[0046] In the present embodiment, the term "(meth)acrylic acid" means that it may be either "acrylic acid" or "methacrylic acid".

[0047] In this embodiment, the “white colorant for electrostatic charge image development” is also referred to as the “white colorant”, the “colored colorant for electrostatic charge image development” is also referred to as the “colored colorant”, the “electrostatic charge image white developer” is also referred to as the “white developer”, and the “electrostatic charge image colored developer” is also referred to as the “colored developer”.

[0048] In the present embodiment, the “toner set for electrostatic image development” is also simply referred to as the “toner set”, and the “electrostatic image developer set” is also simply referred to as the “developer set”.

[0049] <Toner Set for Electrostatic Image Development>

[0050] The toner set of this embodiment includes: a white toner having white toner particles containing a polyester resin and a white colorant; and a non-white colored toner having colored toner particles containing a vinyl resin, a polyester resin, and a colored colorant.

[0051] Furthermore, a mass ratio C of the polyester resin to the vinyl resin in the color toner particles is 0.7 or more and 10 or less.

[0052] In addition, when the cross section of the colored toner particles is observed, the polyester resin forms domains having a maximum diameter of 100 nm or more and 1 μm or less.

[0053] The toner set of the present embodiment has the above-mentioned structure, and can produce a high color formation of an image having a color image on a white image, and can suppress the peeling of the color image. The reason for this is presumably as follows.

[0054] In the application of image formation on recording media such as colored paper such as black paper and films such as beverage labels, there is an application of forming a colored image on a white image as a base in order to improve the color formation of the colored image.

[0055] It is also known that the binder resin of white toner particles includes polyester resin, and the binder resin of color toner particles includes a combination of vinyl resin (styrene acrylic resin, etc.) and polyester resin. The reasons for this are as follows: by using polyester resin in white toner, white colorant is easily dispersed, and by using vinyl resin, whose charge potential is difficult to decrease under high temperature and high humidity, and polyester resin, which has excellent fixability, in color toner, a balance is achieved.

[0056] In order to prevent the colored image from peeling off due to friction or the like, it is preferred that the white image and the colored image are fixed with high adhesion.

[0057] However, in a combination where the binder resin of the white toner particles includes a polyester resin and the binder resin of the color toner particles includes a vinyl resin (styrene acrylic resin, etc.) and a polyester resin, the components of the white toner particles and the color toner particles are difficult to dissolve in each other during fixing, and the adhesion of the color image to the white image becomes low. Therefore, when the image is rubbed, the color image peels off.

[0058] On the other hand, if the components of the white toner particles and the color toner particles are excessively miscible during fixing, the components of the white toner particles and the color toner particles are excessively mixed, resulting in color mixing and deterioration in the color formation of the color image.

[0059] In particular, in low-temperature environments such as winter, the recording medium and toner become cool, so during fixing, the affinity of white toner particles and color toner particles becomes low, and the components of each other are difficult to dissolve, which easily causes the color image to peel off. In addition, in high-temperature environments such as summer, due to continuous image formation, the temperature of the recording medium and toner rises, so the affinity of white toner particles and color toner particles increases, and the components of each other are easily excessively dissolved, and the colorability of the color image is easily reduced.

[0060] Therefore, in the toner set of the present embodiment, the mass ratio C of the polyester resin to the vinyl resin in the color toner particles is 0.7 or more and 10 or less.

[0061] The color toner particles containing the vinyl resin and the polyester resin as the binder resin appropriately contain the vinyl resin having low fixability and the polyester resin causing mixing with the components of the white toner in the above-mentioned mass ratio C.

[0062] Therefore, during fixing, the affinity between the white toner particles and the color toner particles becomes appropriate, the components of the toner particles are appropriately compatible, and the adhesion between the white image and the color image is sufficiently ensured. As a result, peeling of the color image is suppressed.

[0063] In addition, since the toner particles are not excessively miscible, the deterioration of the dispersibility of the white colorant of the white image is suppressed when the excessive components are mixed. As a result, the scattering property of the white image is exerted while the mixing of the white colorant and the colored colorant is suppressed, and the reduction of the color formation of the colored image is suppressed.

[0064] Furthermore, when the cross section of the colored toner particles is observed, the polyester resin forms domains having a maximum diameter of 100 nm or more and 1 μm or less.

[0065] If a domain having a maximum diameter that is appropriately within the above range is formed in the colored toner particles and the polyester resin is present, the polyester resin will be appropriately exuded on the surface of the colored toner particles during fixing. As a result, the colored toner particles are easily soluble on the surface but difficult to be soluble inside the white toner particles containing the polyester resin. Therefore, while ensuring the adhesion of the white image and the colored image, the mixing of the components of the toner particles is suppressed, so the reduction in the colorability of the colored image is also suppressed.

[0066] From the above, it is presumed that the toner set of the present embodiment has high color formation of an image having a color image on a white image, and peeling of the color image is suppressed.

[0067] Next, the toner set according to the present embodiment will be described in detail.

[0068] (Mass ratio C)

[0069] The mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is 0.7 or more and 10 or less.

[0070] When the mass ratio C is less than 0.7, the vinyl resin ratio in the color toner particles is too high, and the white toner particles and the color toner particles are difficult to dissolve during fixing, and the adhesion between the white image and the color image is reduced. Therefore, the color image peeling is aggravated.

[0071] When the mass ratio C exceeds 10, the polyester resin ratio in the colored toner particles is too high, and the polyester resin contained in the colored toner particles is excessively mixed with the polyester resin in the white toner particles during fixing, resulting in mixing of white colorant and colored colorant. In addition, the dispersibility of the white pigment is deteriorated, and the color formation of the colored image is reduced.

[0072] From the viewpoint of suppressing peeling of the color image and improving the color formation of the color image, the mass ratio C is preferably 2 or more and 6 or less, and more preferably 3 or more and 5 or less.

[0073] (Relationship between mass ratio C and mass ratio W)

[0074] When the white toner particles contain a vinyl resin, the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white toner particles and the mass ratio C of the polyester resin to the vinyl resin in the color toner particles preferably satisfies -0.6≤WC≤5.6.

[0075] The relationship WC between the mass ratio W and the mass ratio C more preferably satisfies 0≤WC≤4, and further preferably satisfies 1≤WC≤3.

[0076] If the relationship WC between the mass ratio W and the mass ratio C is within the above range, the relationship between the ratios of the vinyl resin and the polyester resin of the white colorant particles and the color colorant particles becomes appropriate. During fixing, the white colorant particles and the polyester resin of the color colorant particles are moderately mixed, the adhesion between the white image and the color image is fully improved, the reduction in the color formation of the color image is suppressed, and the peeling of the color image is easily suppressed.

[0077] (Measurement of Content of Each Resin Contained in Toner Particles)

[0078] The content of each resin contained in the toner particles (white toner particles and color toner particles) is measured as follows.

[0079] First, each resin contained in the toner particles can be identified by known nuclear magnetic resonance measurement, infrared spectrum measurement, and pyrolysis gas chromatography-mass spectrometry.

[0080] The content of each resin contained in the toner particles can be calculated by centrifugal separation and measurement of 1H-NMR spectrum using a nuclear magnetic resonance apparatus.

[0081] Toner particles (or toner) whose mass is measured in advance are dissolved in toluene, and then centrifuged to separate the resin component and the non-resin component.

[0082] Next, the solution component in which the resin component is dissolved is recovered, and the solvent is removed by drying to obtain the resin component (ie, solid component). Then, the mass ratio of the resin component to the non-resin component solid component is determined based on the mass of the resin component.

[0083] Next, 10 mg of the resin component was dissolved in 0.7 mL of a deuterated chloroform solution, and a solution to which tetramethylsilane (TMS) was added at a concentration of 0.05% by volume as a reference substance was used as a measurement sample.

[0084] Next, the sample was subjected to 1H-NMR spectrum measurement using a nuclear magnetic resonance apparatus (JNM-AL400 (manufactured by JEOL Ltd.) under the following measurement conditions: standard substance: tetramethylsilane (TMS), temperature: 25° C., and cumulative number of times: 128.

[0085] Next, the obtained 1H-NMR spectrum is analyzed to determine the chemical shift and the integrated value ratio, and the molar ratio of each monomer constituting the resin is determined based on the chemical shift and the integrated value ratio.

[0086] Finally, the molar ratio of each monomer is multiplied by the molecular weight of the polymerized segment unit to convert the molar ratio into a mass ratio, thereby determining the content of each resin contained in the toner particles.

[0087] (Polyester resin domain)

[0088] When observing the cross section of the colored toner particles, the polyester resin forms domains with a maximum diameter of 100 nm to 1 μm, preferably 100 nm to 600 nm, more preferably 200 nm to 500 nm.

[0089] When the polyester resin forms a domain with a maximum diameter of less than 100 nm, the polyester resin is difficult to seep onto the surface of the colored toner particles during fixing, so the components of the colored toner and the white toner are difficult to dissolve, and the adhesion between the white image and the colored image is reduced. As a result, it is difficult to suppress the peeling of the colored image.

[0090] When the polyester resin forms a domain with a maximum diameter exceeding 600 nm, the polyester resin excessively oozes out onto the surface of the color toner particles during fixing, and the components of the color toner and the white toner are excessively miscible. As a result, the components of the toner particles are mixed, and the color formation of the color image is reduced.

[0091] The maximum diameter of the domain of the polyester resin may be adjusted by adjusting the first and second temperature increase rates in the coagulation and coalescence method described below.

[0092] (Area ratio of polyester resin present inside the colored toner particles)

[0093] When observing the cross section of the color toner particles, the area ratio of the polyester resin present inside the color toner particles is preferably 3% or more and 25% or less, and more preferably 5% or more and 20% or less.

[0094] If the area ratio of the polyester resin present inside the colored toner particles is within the above range, the polyester resin can easily ooze out to the surface of the colored toner particles during fixing. As a result, during fixing, the colored toner particles are compatible with the white toner particles containing the polyester resin on the surface, but are difficult to be compatible with the inside. Therefore, while ensuring the adhesion of the white image and the colored image, it is easy to suppress the mixing of the components of the toner particles. As a result, it is also easy to suppress the reduction of the colorability of the colored image.

[0095] Regarding the adjustment of the area ratio of the polyester resin present inside the colored toner particles, there can be cited a method of adjusting the amount of hybrid amorphous polyester resin particle dispersion added as the resin particles forming the inside of the colored toner particles in the method for producing the colored toner particles based on the emulsion aggregation method described later.

[0096] (Area ratio of release agent)

[0097] When the white colorant particles and the colored colorant particles contain a release agent, the relationship between the area ratio a of the release agent when observing the cross section of the white colorant particles and the area ratio b of the release agent when observing the cross section of the colored colorant particles preferably satisfies 0.03≤a / b≤0.5, more preferably satisfies 0.05≤a / b≤0.4, and further preferably satisfies 0.08≤a / b≤0.35.

[0098] If the relationship between the area ratio a of the release agent and the area ratio b of the release agent satisfies the above relationship, when an image formed by white toner and color toner is fixed on a recording medium such as paper or film, appropriate peeling properties from the fixing member are obtained. Therefore, the color formation of the image having a color image on the white image is improved, and peeling of the color image is easily suppressed.

[0099] Here, the area ratio a of the release agent when observing the cross section of the white toner particles is preferably 0.5% or more and 8% or less, and more preferably 2% or more and 6% or less.

[0100] (Method for observing the cross section of colored toner particles, method for measuring the maximum diameter of domains, and area ratio of each component)

[0101] The cross-section of the colored toner particles is observed by observing a STEM image using an ultra-high resolution field emission scanning electron microscope (FE-SEM).

[0102] The toner particles (or toner) are embedded in an epoxy resin, and the epoxy resin is cured. The obtained cured product is cut using an ultra-microtome device (Ultracut UCT manufactured by Leica) to prepare a thin slice sample having a thickness of 80 nm to 130 nm.

[0103] Next, the obtained thin-sheet sample was dyed with ruthenium tetroxide for 3 hours in a desiccator at 30° C. Then, the cross-section of the colored toner particles was observed in the transmission imaging mode (accelerating voltage: 30 kV, magnification: 20,000 times) using an ultra-high resolution field emission scanning electron microscope (FE-SEM, manufactured by Hitachi High-Technologies Corporation: S-4800) for the dyed thin-sheet sample to obtain a STEM image.

[0104] In addition, when observing the cross section of the toner, the toner particles whose cross section diameter (long axis) is 85% or more of the number average particle diameter are selected for observation. Here, the cross section diameter of the toner particle refers to the maximum length (so-called long axis) of a straight line drawn from any two points on the contour line of the cross section of the toner particle. In addition, the area of ​​each toner is obtained by image analysis, and the equivalent circle diameter is calculated based on the area value, and the average value of the equivalent circle diameters of 100 pieces of the multiple viewing fields is taken as the number average particle diameter of the toner particles.

[0105] In the observed STEM image, the vinyl resin, polyester resin, and release agent in the toner particles are identified based on the shape and contrast.

[0106] Ruthenium tetroxide based dyes are more receptive to resins with many double bond sites.

[0107] Therefore, the region (domain) where the vinyl resin exists is stained darker than the region (domain) where the polyester resin exists, and the regions (domains) can be distinguished based on this contrast. In addition, the region (domain) where the release agent exists is stained the lightest.

[0108] Furthermore, the contrast is adjusted so that the region (domain) where the vinyl resin exists appears dark gray, the region (domain) where the polyester resin exists appears light gray, and the region (domain) where the release agent exists appears white.

[0109] Next, the maximum diameter of the polyester resin domain present in the cross section of the colored toner particle in the STEM image obtained by cross-sectional observation of the colored toner particle is measured. This operation is performed on 100 colored toner particles, and the arithmetic mean of the maximum diameters of all the obtained polyester resins is calculated.

[0110] In addition, in the cross section of the colored toner particle in the STEM image obtained by cross-sectional observation of the colored toner particle, the area between the position of 150 nm inside from the edge and the position of 1 / 2 of the length from the center of gravity to the surface of the cross section of the colored toner particle is defined as the internal area of ​​the colored toner particle. The area of ​​the polyester resin present in the internal area is calculated, and the ratio of the area of ​​the polyester resin present in the internal area to the area of ​​the internal area is calculated. These operations are performed on 100 colored toner particles, and the arithmetic mean of the ratio (%) of the area of ​​the polyester resin present in the internal area is calculated.

[0111] In addition, in the cross section of each toner particle obtained by STEM images of the cross section of the colored toner and the white toner, the total area of ​​the domains of each release agent present is obtained. Then, the ratio (%) of the area of ​​each release agent domain to the total of the cross section of each toner particle is obtained. Then, these operations are performed on 100 colored toner particles, and the arithmetic mean of the total ratio (%) of the area of ​​each release agent domain is obtained.

[0112] In this way, the area ratio a of the release agent when the cross section of the white toner particle is observed and the area ratio b of the release agent when the cross section of the color toner particle is observed are determined.

[0113] Furthermore, the cross-sectional area and cross-sectional diameter of the colored toner particles and the area of ​​the resin in the STEM image were measured by analysis using an image processing and analysis system (LUZEX AP manufactured by NIRECO CORPORATION).

[0114] (White toner lower number particle size distribution index)

[0115] The lower number size distribution index (lower GSDw) of the white toner is preferably 1.2 or more and 1.54 or less, more preferably 1.2 or more and 1.4 or less, and further preferably 1.2 or more and 1.35 or less.

[0116] Here, if a white image is formed on a recording medium with large surface irregularities such as embossed paper, it is difficult to fill the concave portions of the recording medium with white toner. In this state, when the white toner image is fixed, the filling rate of the white toner in the concave portions of the recording medium is low, so the thermal conductivity of the white toner in the concave portions of the recording medium is low, and the white toner is difficult to melt. As a result, the fixability is low, and the white image is prone to peeling.

[0117] In contrast, by making the lower number particle size distribution index (lower GSDw) of the white colorant greater than 1.2, the fine powder of the white colorant is increased. As a result, the fine powder of the white colorant enters the concave portion of the recording medium, and the filling rate is improved. Therefore, during fixing, the thermal conductivity of the white colorant in the concave portion of the recording medium is improved, and the white colorant is easily melted. As a result, the fixability is improved, and the peeling of the white image is suppressed. On the other hand, by making the lower GSDw of the white colorant less than 1.54, when there is too much fine powder, the number of particles filling the concave portion of the recording medium increases, and the pressure is dispersed, thereby suppressing the reduction in fixability and the deterioration of the peeling of the white image.

[0118] (Relationship between the lower number particle size distribution index of white toner and color toner)

[0119] The ratio (lower GSDw / lower GSDc) of the lower number particle size distribution index (lower GSDw) of the white colorant to the lower number particle size distribution index (lower GSDc) of the color colorant is preferably 1.0 or more and 1.4 or less, more preferably 1.0 or more and 1.3 or less, and further preferably 1.0 or more and 1.25 or less.

[0120] That is, it is preferred to make the lower number particle size distribution index (lower GSDw) of the fine powder of the colored toner the same as or slightly smaller than the lower number particle size distribution index (lower GSDc) of the white toner, and to make the fine powder amount of the colored toner the same as or slightly smaller than that of the white toner.

[0121] Thus, when the white toner image and the colored toner image are overlapped, the colored toner enters the unevenness of the white toner layer surface, and the gap between the white toner layer and the colored toner layer becomes smaller. As a result, the adhesion between the white toner layer and the colored toner layer is improved, and the peeling of the colored image is suppressed.

[0122] In particular, when a recording medium with a large surface unevenness is used, the unevenness of the surface of the white toner layer tends to become larger, and when a color toner layer is placed on the white toner layer, the gap between the two layers tends to become larger. Therefore, by setting the ratio (lower GSDw / lower GSDc) and the lower side number particle size distribution index (lower GSDw) of the white toner to the above range, the fine powder of the color toner enters the unevenness of the surface of the white toner layer, and when the white toner layer and the color toner layer are overlapped, the color toner enters the unevenness of the surface of the white toner layer, and the gap between the white toner layer and the color toner layer becomes smaller. As a result, the adhesion between the white toner layer and the color toner layer is improved, and the peeling of the color image is suppressed.

[0123] Here, the lower number particle size distribution indexes of the white toner and the color toner are adjusted by classifying the toner particles and the like.

[0124] The lower number particle size distribution index of the white toner and the color toner was measured using Coulter Multisizer II (manufactured by Beckman Coulter) and ISOTON-II (manufactured by Beckman Coulter) for the electrolyte.

[0125] In the measurement, 0.5 mg to 50 mg of the measurement sample is added as a dispersant to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate), and the solution is added to 100 ml to 150 ml of the electrolyte.

[0126] The electrolyte in which the sample was suspended was dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size of 2 μm or more and 60 μm or less was measured using a Coulter Multisizer II with an aperture of 100 μm. In addition, the number of particles sampled was 50,000.

[0127] For the particle size ranges (channels) divided according to the measured particle size distribution, cumulative distribution is plotted for the number of particles from the smaller diameter side, and the cumulative particle size of 16% is defined as the number average particle size D16p, and the cumulative particle size of 50% is defined as the number average particle size D50p.

[0128] Using these values, the lower number size distribution index (lower GSDp) was calculated as (D50p / D16p).

[0129] <Constitution of White Toner and Color Toner>

[0130] Next, constituent components of the toners (white toner and color toners) contained in the toner set according to the present embodiment will be described.

[0131] The toner in this embodiment includes toner particles and may further include an external additive.

[0132] Here, the colored toner, colored toner particles, colored colorant, and colored image refer to toners, toner particles, colorants, and images having colors other than white. For example, the colored toners include color toners such as yellow (Y), magenta (M), cyan (C), and black (K) toners.

[0133] In addition, a plurality of color toners may be used in combination as the color toners. For example, four color toners, namely yellow toner, magenta toner, cyan toner and black toner, may be used in combination to form a toner set together with a white toner. In this case, it is preferred that at least one color toner of the color toners satisfies the above conditions, and it is preferred that all the color toners used in combination satisfy the above conditions.

[0134] (Toner particles)

[0135] The white toner particles contain a polyester resin as a binder resin and a white colorant. The white toner particles may also contain a polyester resin and a vinyl resin as a binder resin.

[0136] The colored toner particles contain a vinyl resin and a polyester resin as a binder resin and a colored colorant.

[0137] The toner particles (white toner particles and colored toner particles) may contain a release agent and other additives.

[0138] Each component is described below.

[0139] -Bonding resin-

[0140] The polyester resin will be described.

[0141] As the polyester resin, for example, a known amorphous polyester resin can be cited. The polyester resin may be amorphous polyester resin and a crystalline polyester resin used together. However, the crystalline polyester resin can be used in a range of 2% by mass or more and 40% by mass or less (preferably 2% by mass or more and 20% by mass or less) relative to the total binder resin.

[0142] The "crystallinity" of a resin means that in differential scanning calorimetry (DSC), the resin has a clear endothermic peak instead of a stepwise change in endothermic value. Specifically, the half-value width of the endothermic peak is within 10°C when measured at a heating rate of 10 (°C / min).

[0143] On the other hand, the "amorphous" nature of a resin means that the half value width exceeds 10°C, the endothermic value changes stepwise, or a clear endothermic peak is not observed.

[0144] Amorphous polyester resin

[0145] Examples of the non-crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. In addition, as the non-crystalline polyester resin, a commercially available product may be used, or a synthetic resin may be used.

[0146] Examples of the polycarboxylic acid include: aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.); alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.); aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.); anhydrides thereof, or lower (e.g., carbon number 1 to 5) alkyl esters thereof. Among these, the polycarboxylic acid is preferably, for example, an aromatic dicarboxylic acid.

[0147] The polycarboxylic acid may also be used in combination with a dicarboxylic acid and a trivalent or higher carboxylic acid having a cross-linked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., carbon number 1 to 5) alkyl esters.

[0148] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0149] Examples of the polyol include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among them, the polyol is preferably an aromatic diol or an alicyclic diol, and more preferably an aromatic diol.

[0150] As the polyol, a diol and a trivalent or higher polyol having a cross-linked structure or a branched structure may be used in combination. Examples of the trivalent or higher polyol include glycerin, trimethylolpropane, and pentaerythritol.

[0151] The polyols may be used alone or in combination of two or more.

[0152] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower.

[0153] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, by "extrapolated glass transition start temperature" described in the method for determining glass transition temperature in JIS K 7121-1987 "Methods for determining transition temperatures of plastics".

[0154] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less.

[0155] The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less.

[0156] The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0157] In addition, the weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). In the molecular weight measurement based on GPC, GPC HLC-8120GPC manufactured by Tosoh is used as a measuring device, TSKgel SuperHM-M (15 cm) manufactured by Tosoh is used, and THF solvent is used. The weight average molecular weight and the number average molecular weight are calculated based on the measurement results using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

[0158] The amorphous polyester resin can be obtained by a well-known production method. Specifically, for example, the amorphous polyester resin can be obtained by setting the polymerization temperature to 180° C. to 230° C., reducing the pressure in the reaction system as necessary, and reacting while removing water or alcohol generated during condensation.

[0159] In addition, when the monomer of the raw material is insoluble or incompatible at the reaction temperature, a high boiling point solvent may be added as a cosolvent to dissolve it. In this case, the polycondensation reaction is carried out while the cosolvent is distilled off. In the case of the presence of monomers with poor compatibility, the monomers with poor compatibility may be condensed with an acid or alcohol to be polycondensed with the monomers in advance, and then polycondensed with the main component.

[0160] Crystalline polyester resin

[0161] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. In addition, as the crystalline polyester resin, a commercially available product may be used, and a synthetic resin may also be used.

[0162] Here, in order to easily form a crystalline structure, it is preferable to use a polycondensate of a polymerizable monomer having a linear aliphatic group rather than a polycondensate of a polymerizable monomer having an aromatic group.

[0163] Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid, etc.), anhydrides thereof, or lower (e.g., carbon number of 1 to 5) alkyl esters thereof.

[0164] The polycarboxylic acid may be used in combination with a dicarboxylic acid and a trivalent or higher carboxylic acid having a cross-linked structure or a branched structure. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., carbon number 1 to 5) alkyl esters.

[0165] As the polycarboxylic acid, these dicarboxylic acids may be used in combination with a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond.

[0166] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0167] Examples of the polyol include aliphatic diols (e.g., linear aliphatic diols having a main chain portion having carbon atoms of 7 or more and 20 or less). Examples of the aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,12-eicosandiol. Among them, preferred aliphatic diols include 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0168] The polyol may be used together with the diol in a trivalent or higher alcohol having a cross-linked structure or a branched structure. Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0169] The polyols may be used alone or in combination of two or more.

[0170] Here, the content of the aliphatic diol in the polyol can be 80 mol % or more, preferably 90 mol % or more.

[0171] The melting temperature of the crystalline polyester resin is preferably 50° C. or higher and 100° C. or lower, more preferably 55° C. or higher and 90° C. or lower, and further preferably 60° C. or higher and 85° C. or lower.

[0172] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) using the “melting peak temperature” described in the method for determining the melting temperature in JIS K 7121-1987 “Methods for determining transition temperatures of plastics”.

[0173] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0174] The crystalline polyester resin can be obtained by a known production method, for example, similarly to the amorphous polyester.

[0175] Vinyl resin will be described.

[0176] Examples of the vinyl resin include a vinyl resin composed of a homopolymer of the following monomers or a copolymer of two or more of these monomers, wherein the monomers include styrenes (e.g., styrene, p-chlorostyrene, α-methylstyrene, etc.), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g., ethylene, propylene, butadiene, etc.), and the like.

[0177] These vinyl resins may be used alone or in combination of two or more.

[0178] As the vinyl resin, styrene acrylic resin is preferred from the viewpoint of excellent environmental stability of toner charging.

[0179] Styrene acrylic resin is a copolymer obtained by copolymerizing at least a styrene monomer (a monomer having a styrene skeleton) and a (meth) acrylic monomer (a monomer having a (meth) acryloyl group, preferably a monomer having a (meth) acryloyl group). Styrene acrylic resin includes, for example, a copolymer of a styrene monomer and the above-mentioned (meth) acrylate monomer. In addition, the acrylic resin part in the styrene acrylic resin is any one of an acrylic monomer and a methacrylic monomer or a partial structure obtained by polymerizing them. In addition, "(meth) acrylic acid" is an expression including any one of "acrylic acid" and "methacrylic acid".

[0180] As the styrene monomer, for example, specifically, styrene, alkyl-substituted styrene (e.g., α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrene (e.g., 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), vinylnaphthalene, etc. The styrene monomer may be used alone or in combination of two or more.

[0181] Among them, as the styrene-based monomer, styrene is preferred from the viewpoints of easy reaction, easy reaction control, and availability.

[0182] Examples of the (meth)acrylic monomers include, for example, (meth)acrylic acid and (meth)acrylic acid esters. Examples of the (meth)acrylic acid esters include, for example, alkyl (meth)acrylic acid esters (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isopentyl (meth)acrylate, and n-octadecyl (meth)acrylate). Amyl acrylate, neopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, etc.), aryl (meth)acrylate (for example, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, tert-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, etc.), dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, β-carboxyethyl (meth)acrylate, (meth)acrylamide, etc. The (meth)acrylic monomer may be used alone or in combination of two or more.

[0183] Furthermore, among these (meth)acrylates in the (meth)acrylic monomers, from the viewpoint of improving the fixability of the toner, (meth)acrylates having an alkyl group having 2 to 14 carbon atoms (preferably 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms) are preferred. Among them, n-butyl (meth)acrylate is preferred, and n-butyl acrylate is particularly preferred.

[0184] The copolymerization ratio of the styrene-based monomer and the (meth)acrylic-based monomer (based on mass, styrene-based monomer / (meth)acrylic-based monomer) is not particularly limited, but is preferably 98 / 2 to 60 / 40.

[0185] The styrene acrylic resin preferably has a crosslinked structure. As the styrene acrylic resin having a crosslinked structure, for example, preferably there is mentioned a resin obtained by copolymerizing at least a styrene-based monomer, a (meth)acrylic-based monomer, and a crosslinkable monomer.

[0186] Examples of the crosslinkable monomer include bifunctional or higher-functional crosslinking agents.

[0187] Examples of the bifunctional crosslinking agent include divinylbenzene, divinylnaphthalene, di(meth)acrylate compounds (e.g., diethylene glycol di(meth)acrylate, methylenebis(meth)acrylamide, decanediol diacrylate, glycidyl(meth)acrylate, etc.), polyester di(meth)acrylate, and 2-([1'-methylpropyleneamino]carboxyamino)ethyl methacrylate.

[0188] Examples of trifunctional or higher crosslinking agents include tri(meth)acrylate compounds (e.g., pentaerythritol tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.), tetra(meth)acrylate compounds (e.g., pentaerythritol tetra(meth)acrylate, oligoester (meth)acrylate, etc.), 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, and diallyl chlorendic acid.

[0189] Among them, as the crosslinking monomer, from the viewpoint of improving the fixing property of the toner, a (meth)acrylate compound having two or more functions is preferred, a difunctional (meth)acrylate compound is more preferred, a difunctional (meth)acrylate compound having an alkylene group having 6 to 20 carbon atoms is further preferred, and a difunctional (meth)acrylate compound having a linear alkylene group having 6 to 20 carbon atoms is particularly preferred.

[0190] The copolymerization ratio of the crosslinkable monomer to all monomers (based on mass, crosslinkable monomer / all monomers) is not particularly limited, but is preferably 2 / 1,000 to 20 / 1,000.

[0191] From the viewpoint of improving the fixing property of the toner, the glass transition temperature (Tg) of the styrene acrylic resin is preferably 40° C. or higher and 75° C. or lower, and more preferably 50° C. or higher and 65° C. or lower.

[0192] Here, the glass transition temperature of the resin is determined from a DSC curve obtained by differential scanning calorimetry (DSC). More specifically, the glass transition temperature of the resin is determined by "extrapolating the glass transition start temperature" described in the method for determining the glass transition temperature of JIS K 7121:1987 "Methods for determining transition temperatures of plastics".

[0193] From the viewpoint of storage stability of the toner, the weight average molecular weight of the styrene acrylic resin is preferably 5,000 or more and 200,000 or less, more preferably 10,000 or more and 100,000 or less, and particularly preferably 20,000 or more and 80,000 or less.

[0194] Here, the weight average molecular weight and number average molecular weight of the resin are measured by gel permeation chromatography (GPC). In the molecular weight measurement based on GPC, GPC HLC-8120GPC manufactured by Tosoh is used as a measuring device, a chromatographic column TSKgel SuperHM-M (15 cm) manufactured by Tosoh is used, and THF solvent is used. The weight average molecular weight and number average molecular weight are calculated based on the measurement results using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

[0195] The method for preparing the styrene acrylic resin is not particularly limited, and various polymerization methods (such as solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.) are applicable. In addition, the polymerization reaction is applicable to known operations (such as batch, semi-continuous, continuous, etc.).

[0196] Here, the coexistence of the styrene acrylic resin and the polyester resin can be achieved by mixing the individual resins, or by providing a hybrid resin having a chemical bond between a styrene acrylic resin segment and a polyester resin segment (so-called styrene acrylic modified polyester resin). Specifically, a hybrid resin can be obtained by polymerizing a polyester monomer having an unsaturated structure such as fumaric acid or succinic acid or a resin containing such a monomer structure as a prepolymer with a vinyl monomer such as styrene or acrylic acid.

[0197] Furthermore, when a hybrid resin (so-called styrene acrylic modified polyester resin) is used, the mass ratios C and W of the polyester resin to the vinyl resin are measured and calculated as the mass ratio of the polyester segment of the hybrid resin to the vinyl resin segment (e.g., styrene acrylic resin segment). Furthermore, when a hybrid resin, a vinyl resin (e.g., styrene acrylic resin), and a polyester resin are used in combination, the mass ratio of the sum of the polyester resin segment and the polyester resin of the hybrid resin to the sum of the vinyl resin segment and the vinyl resin of the hybrid resin is measured and calculated.

[0198] -Colorants-

[0199] When the colorant is white toner particles, a white colorant is used, and when the colorant is colored toner particles, a colored colorant other than the white colorant is used.

[0200] However, in the case of white toner particles, if 15% by mass or more of a white colorant is contained based on the toner particles, the toner particles are regarded as white toner even if they contain a colored colorant.

[0201] --White colorant--

[0202] Examples of the white colorant include inorganic pigments and organic pigments.

[0203] As white colorants, specifically, among inorganic pigments, heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, and montmorillonite, and among organic pigments, polystyrene-based resin particles, urea-formaldehyde resin particles, and the like can be mentioned.

[0204] Among them, from the viewpoint of forming a white image with higher concealability and a more excellent color tone of a colored image, the white colorant is preferably at least one selected from the group consisting of titanium oxide, silicon dioxide, aluminum oxide, zinc oxide, and zirconium oxide.

[0205] In particular, as a white colorant, titanium oxide is preferred from the viewpoint of excellent hiding property. The crystal structure of titanium oxide may be any of anatase type, rutile type, and brookite type.

[0206] As the white colorant, a surface-treated white colorant may be used as required, and a dispersant may be used in combination.

[0207] The white coloring agent may be used alone or in combination of two or more.

[0208] The content of the white colorant is preferably 15% by mass or more and 65% by mass or less, more preferably 20% by mass or more and 60% by mass or less, and further preferably 30% by mass or more and 50% by mass or less, based on the entire white toner particles.

[0209] When the content of the white colorant is within the above range, image peeling is suppressed, the reflectance of the white image is improved, and the color formation of the colored image is easily improved.

[0210] --Colored colorants--

[0211] Examples of the colored colorant include carbon black, chrome yellow, Hansa yellow, benzidine yellow, vat yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, sulfur-resistant orange, lake red, permanent red, brilliant carmine 3B, brilliant carmine 6B, Dupont Oil Red, pyrazolone red, litho red, rhodamine B lake, lake red C, pigment red, rose Bengal, aniline blue, ultramarine blue, oil-soluble blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate and other pigments; and acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, nigrosine-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, thiazole-based and other dyes.

[0212] The colored coloring agents may be used alone or in combination of two or more.

[0213] The content of the colored colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less, based on the entire colored toner particles.

[0214] - Anti-sticking agent -

[0215] As the anti-adhesive agent, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, aliphatic hydrocarbon wax such as Fischer-Tropsch wax, oxides of aliphatic hydrocarbon wax such as oxidized polyethylene wax or waxes composed of their block copolymers, in addition to carnauba wax, montanic acid ester wax, ester waxes with fatty acid ester as the main component such as behenyl behenate can be used. The anti-adhesive agent for the colored toner particles is preferably an ester wax. Since it has an ester structure, it has a high chemical affinity with the polyester resin in the binder resin and is easy to suppress the peeling of the colored image.

[0216] -Other additives-

[0217] Examples of other additives include known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in toner particles as internal additives.

[0218] -Characteristics of toner particles, etc.-

[0219] The toner particles may be toner particles of a single-layer structure, or may be toner particles of a so-called core / shell structure consisting of a core (core particle) and a coating layer (shell layer) that covers the core.

[0220] Here, the toner particles of the core / shell structure may be composed of, for example, a core portion including a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer including a binder resin.

[0221] The volume average particle size of the toner particles has a range suitable for white toner particles and color toner particles, respectively.

[0222] Volume average particle size D of white toner particles W The thickness is preferably 5.0 μm or more and 10.0 μm or less, and more preferably 6.0 μm or more and 9.0 μm or less.

[0223] Volume average particle size D of the colored toner particles C The thickness is preferably 3.0 μm or more and 8.0 μm or less, and more preferably 4.0 μm or more and 7.0 μm or less.

[0224] The volume average particle size of the toner particles was measured using Coulter Multisizer II (manufactured by Beckman Coulter Coulter Co.) and the electrolyte was measured using ISOTON-II (manufactured by Beckman Coulter Coulter Co.).

[0225] In the measurement, 0.5 mg to 50 mg of the measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and then added to 100 ml to 150 ml of an electrolyte.

[0226] The electrolyte in which the sample was suspended was dispersed by an ultrasonic disperser for 1 minute, and the particle size distribution of particles with a particle size of 2 μm or more and 60 μm or less was measured by Coulter Multisizer II using an aperture of 100 μm. The number of particles sampled was 50,000.

[0227] For the particle size range (channel) divided according to the measured particle size distribution, the volume and number are respectively plotted as cumulative distributions starting from the smaller diameter side, the cumulative 16% particle size is defined as the volume particle size D16v and the number particle size D16p, and the cumulative 50% particle size is defined as the volume average particle size D50v.

[0228] The average circularity of the toner particles is preferably 0.90 or more and 1.00 or less, and more preferably 0.92 or more and 0.98 or less.

[0229] The average circularity of the toner particles is obtained by (equivalent circular circumference) / (circumference) [(circumference of a circle having the same projected area as the particle image) / (circumference of the particle projected image)]. Specifically, it is a value measured by the following method.

[0230] First, the toner particles to be measured are sucked and collected to form a flat flow, and the particle image is captured as a still image by instantaneously strobing the toner particles. The particle image is analyzed by a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation) to obtain the average circularity. The number of samples sampled when obtaining the average circularity is 3,500.

[0231] When the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant and then subjected to ultrasonic treatment to obtain toner particles from which the external additive has been removed.

[0232] (External Additives)

[0233] Examples of the external additive include inorganic particles. Examples of the inorganic particles include SiO2, TiO2, SrTiO3, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2) n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0234] From the viewpoint of suppressing the peeling of the colored image and improving the light scattering property of the white image, thereby easily improving the color forming property of the colored image, SiO 2 is preferred as the external additive.

[0235] The surface of the inorganic particles as an external additive can be subjected to hydrophobic treatment. The hydrophobic treatment is carried out, for example, by impregnating the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and for example, silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, etc. can be cited. They can be used alone or in combination of two or more.

[0236] The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the inorganic particles.

[0237] Examples of the external additives include resin particles (polystyrene, polymethyl methacrylate (PMMA), melamine resin and other resin particles), detergent active agents (metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based high molecular weight bodies).

[0238] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 6.0% by mass or less, based on the toner particles.

[0239] (Method for producing toner)

[0240] Next, a method for producing the toner (white toner and color toner) according to the present embodiment will be described.

[0241] The toner according to the present embodiment is obtained by manufacturing toner particles and then adding an external additive to the toner particles.

[0242] The toner particles can be produced by any of dry methods (e.g., kneading and pulverization methods) and wet methods (e.g., aggregation and coalescence methods, suspension polymerization methods, dissolution and suspension methods, etc.) There are no particular limitations on the methods for producing the toner particles, and a known method can be used.

[0243] Among them, white toner particles are preferably produced by a kneading and pulverizing method, while color toner particles are preferably produced by an aggregation and coalescence method.

[0244] An example of the kneading and pulverizing method and the agglomeration and coalescence method will be described below. However, in the description of each production method, the colors are not distinguished.

[0245] (Mixing and pulverizing method)

[0246] The kneading and pulverizing method is a method of obtaining toner particles through a kneading step of melting and kneading to obtain a kneaded product and a pulverizing step of pulverizing the obtained kneaded product.

[0247] -Mixing process-

[0248] The kneading step kneads the toner particle forming material including the binder resin and the white colorant, etc. The toner particle forming material may contain other additives such as a release agent as necessary.

[0249] In the kneading step, preferably, 0.5 parts by mass or more and 5 parts by mass or less of an aqueous medium (eg, water such as distilled water or ion-exchanged water, alcohol, etc.) is added to 100 parts by mass of the toner particle forming material.

[0250] Examples of the kneading machine used in the kneading step include a single-screw extruder, a twin-screw extruder, etc. Hereinafter, as an example of a kneading machine, a kneading machine having a feed screw portion and two kneading portions will be described with reference to the drawings, but the invention is not limited thereto.

[0251] like Figure 3 As shown, the screw extruder 11 comprises: a roller 12 having a screw (not shown); an injection port 14 for injecting a colorant particle forming material as a colorant raw material into the roller 12; a liquid addition port 16 for adding an aqueous medium to the colorant particle forming material in the roller 12; and a discharge port 18 for discharging a mixture formed by kneading the colorant particle forming material in the roller 12.

[0252] The roller 12 is divided into, starting from the side close to the injection port 14, a feed screw portion SA for conveying the colorant particle forming material injected from the injection port 14 to the kneading portion NA, a kneading portion NA for melt-kneading the colorant particle forming material through a first kneading process, a feed screw portion SB for conveying the colorant particle forming material melt-kneaded in the kneading portion NA to the kneading portion NB, a kneading portion NB for melt-kneading the colorant particle forming material through a second kneading process to form a mixture, and a feed screw portion SC for conveying the formed mixture to the discharge port 18.

[0253] A different temperature control device (not shown) is provided for each block in the drum 12. That is, the blocks 12A to 12J are configured to be controlled to different temperatures.

[0254] also, Figure 3 This shows a state where the temperature of blocks 12A and 12B is controlled to t0° C., the temperature of blocks 12C to 12E is controlled to t1° C., and the temperature of blocks 12F to 12J is controlled to t2° C. Therefore, the toner particle forming material in the kneading section NA is heated to t1° C., and the toner particle forming material in the kneading section NB is heated to t2° C.

[0255] When the toner particle forming material is supplied from the injection port 14 to the roller 12, the toner particle forming material is fed to the kneading section NA through the feeding screw section SA. At this time, since the temperature of the block 12C is set to t1°C, the toner particle forming material is sent to the kneading section NA in a state where it is heated and changed to a molten state. Moreover, since the temperatures of the blocks 12D and 12E are also set to t1°C, the toner particle forming material is melt-kneaded at a temperature of t1°C in the kneading section NA. The binder resin and the release agent become a molten state in the kneading section NA and are sheared by the screw.

[0256] Next, the toner particle forming material kneaded in the kneading section NA is fed to the kneading section NB by the feeding screw section SB.

[0257] Next, in the feed screw portion SB, the aqueous medium is injected into the drum 12 from the liquid adding port 16 , thereby adding the aqueous medium to the toner particle forming material.

[0258] In addition, although the method of injecting the aqueous medium into the feed screw section SB is shown, the present invention is not limited thereto, and the aqueous medium may be injected into the kneading section NB, or may be injected into both the feed screw section SB and the kneading section NB. That is, the position and number of injection locations for the aqueous medium injection are selected as needed.

[0259] By injecting the aqueous medium into the drum 12 from the liquid addition port 16 , the toner particle forming material and the aqueous medium in the drum 12 are mixed, and the toner particle forming material is cooled by the evaporation latent heat of the aqueous medium to maintain the temperature of the toner particle forming material.

[0260] Finally, the kneaded product melt-kneaded in the kneading section NB is conveyed to the discharge port 18 by the feed screw section SC, and is discharged from the discharge port 18 .

[0261] As mentioned above, use Figure 3 The kneading step of the screw extruder 11 is shown.

[0262] -Cooling process-

[0263] The cooling step is a step of cooling the molten kneaded product formed in the above-mentioned melt-kneading step. In the cooling step, it is preferred to cool the kneaded product from the temperature of the kneaded product at the end of the kneading step to below 40°C at an average temperature drop rate of 4°C / sec or more. When the cooling rate of the kneaded product is slow, sometimes the mixture (a mixture of a binder resin and a colorant, etc.) finely dispersed in the binder resin in the kneading step is recrystallized, and the dispersion diameter becomes larger. On the other hand, if it is quenched at the above-mentioned average temperature drop rate, the dispersion state immediately after the kneading step remains unchanged, so it is preferred. In addition, the above-mentioned average temperature drop rate refers to the temperature of the kneaded product at the end of the kneading step (for example, using Figure 3 The average value of the speed at which the screw extruder 11 is cooled to 40°C at t2°C.

[0264] As a cooling method in the cooling process, specifically, for example, a method using a roller and a sandwich cooling belt that circulates cold water or salt water can be cited. In addition, when cooling is performed by the above method, the cooling rate is determined by the speed of the roller, the flow rate of the salt water, the supply amount of the kneaded product, the thickness of the slab when the kneaded product is rolled, etc. The slab thickness is preferably 1 mm or more and 3 mm or less.

[0265] - Crushing process-

[0266] The kneaded product after cooling by the cooling step is pulverized by a pulverizing step to form particles. In the pulverizing step, for example, a mechanical pulverizer, a jet pulverizer, etc. are used. In addition, the particles can also be heat-treated with hot air etc. as required to make them spherical.

[0267] -Grading process-

[0268] The particles obtained by the pulverization process may be classified by a classification process as needed in order to obtain toner particles with a volume average particle size within a target range. In the classification process, fine powder (particles with a particle size smaller than the target range) and coarse powder (particles with a particle size larger than the target range) are removed using a currently used centrifugal classifier, inertial classifier, etc.

[0269] Through the above steps, toner particles are obtained.

[0270] (Agglomeration method)

[0271] The aggregation and coalescence method is a method for producing toner particles through the following steps, for example:

[0272] a step of preparing each dispersion liquid (dispersion liquid preparation step);

[0273] A step of mixing a first resin particle dispersion in which first resin particles serving as a binder resin are dispersed, a colorant dispersion in which a colorant is dispersed, and a release agent particle dispersion in which particles of a release agent (hereinafter also referred to as “release agent particles”) are dispersed, and aggregating the particles and the colorant in the obtained dispersion to form first aggregated particles (first aggregated particle forming step);

[0274] After obtaining a first aggregated particle dispersion in which first aggregated particles are dispersed, second resin particles serving as a binder resin are added to the first aggregated particle dispersion to aggregate the second resin particles on surfaces of the first aggregated particles to form second aggregated particles (second aggregated particle forming step); and

[0275] A step of heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and aggregate the second aggregated particles to form toner particles (fusion and aggregation step).

[0276] Furthermore, the present aggregation and coalescence method is described as a method for producing toner particles containing a binder resin, a colorant, and a release agent, but the release agent is a component contained in the toner particles as necessary.

[0277] -Each dispersion preparation step-

[0278] First, each dispersion used in the aggregation and coalescence method is prepared. Specifically, a first resin particle dispersion in which first resin particles serving as a binder resin are dispersed, a colorant dispersion in which a colorant is dispersed, a second resin particle dispersion in which second resin particles serving as a binder resin are dispersed, and a release agent particle dispersion in which release agent particles are dispersed are prepared.

[0279] In addition, in each dispersion preparation step, the first resin particles and the second resin particles are described as “resin particles”.

[0280] Here, the resin particle dispersion is prepared by, for example, dispersing the resin particles in a dispersion medium using a surfactant.

[0281] Examples of the dispersion medium used for the resin particle dispersion include aqueous media.

[0282] Examples of the aqueous medium include water such as distilled water and ion-exchanged water, and alcohols, etc. These may be used alone or in combination of two or more.

[0283] As surfactants, for example, anionic surfactants such as sulfate ester salts, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols, etc. can be cited. Among them, anionic surfactants and cationic surfactants can be cited in particular. Nonionic surfactants can also be used in combination with anionic surfactants or cationic surfactants.

[0284] The surfactant may be used alone or in combination of two or more.

[0285] In the resin particle dispersion, as a method for dispersing the resin particles in the dispersion medium, for example, general dispersion methods such as a rotary shearing homogenizer, a ball mill with a medium, a sand mill, a bead mill, etc. are mentioned. In addition, depending on the type of the resin particles, for example, a phase inversion emulsification method can also be used to disperse the resin particles in the resin particle dispersion.

[0286] In addition, the phase inversion emulsification method is the following method: the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) for neutralization, and then an aqueous medium (W phase) is added, thereby converting the resin from W / O to O / W (the so-called phase inversion) without converting it to a continuous phase, so that the resin is dispersed in the aqueous medium in the form of particles.

[0287] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less.

[0288] In addition, the volume average particle size of the resin particles is obtained by measuring the particle size distribution using a laser diffraction particle size distribution measuring device (e.g., LA-700 manufactured by Horiba, Ltd.), and for the divided particle size range (channel), a cumulative distribution is plotted for the volume from the small particle size side, and the particle size at which the accumulation is 50% relative to all particles is measured, which is taken as the volume average particle size D50v. In addition, the volume average particle size of particles in other dispersions is also measured in the same manner.

[0289] The content of the resin particles in the resin particle dispersion is, for example, preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0290] In addition, the same operation as the resin particle dispersion is performed, for example, a colorant dispersion and a release agent particle dispersion are also prepared. That is, the volume average particle size of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the content of the particles are the same for the colorant dispersed in the colorant dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0291] -First Aggregate Particle Formation Step-

[0292] Next, the first resin particle dispersion, the colorant dispersion, and the release agent particle dispersion are mixed.

[0293] Then, in the mixed dispersion, the first resin particles, the colorant, and the release agent particles are heterogeneously aggregated to form first aggregated particles containing the first resin particles, the colorant, and the release agent particles.

[0294] Specifically, for example, a coagulant is added to a dispersion obtained by mixing a first resin particle dispersion, a colorant dispersion, and an anti-sticking agent particle dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of greater than 2 and less than 5). After adding a dispersion stabilizer as needed, the temperature is set to a range of greater than 20°C and less than 50°C to cause the particles dispersed in the mixed dispersion to agglomerate to form first agglomerated particles.

[0295] In the first agglomerated particle formation step, for example, the above-mentioned coagulant can be added at room temperature (for example, 25° C.) while the mixed dispersion is stirred using a rotary shearing homogenizer, the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of greater than 2 and less than 5), and a dispersion stabilizer is added as needed, followed by the above-mentioned heating.

[0296] As the coagulant, for example, a surfactant having a polarity opposite to that of the surfactant used as a dispersant added to the mixed dispersion, an inorganic metal salt, or a divalent or higher metal complex can be cited. In particular, when a metal complex is used as the coagulant, the amount of the surfactant used is reduced, and the charging characteristics are improved.

[0297] If necessary, an additive that forms a complex or similar bond with the metal ion of the coagulant may be used. As such an additive, a chelating agent is preferably used.

[0298] Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0299] As the chelating agent, a water-soluble chelating agent may also be used. Examples of the chelating agent include carboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).

[0300] The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and 3.0 parts by mass or less, based on 100 parts by mass of the first resin particles.

[0301] -Second Aggregate Particle Formation Step-

[0302] Next, after obtaining the first aggregated particle dispersion in which the first aggregated particles are dispersed, the mixed dispersion in which the second resin particles and the release agent particles are dispersed is added to the first aggregated particle dispersion.

[0303] In the second aggregated particle forming step, a surfactant may be added to the first aggregated particle dispersion.

[0304] In addition, the second resin particles may be of the same kind as the first resin particles or of a different kind.

[0305] Then, in the dispersion containing the first aggregated particles and the second resin particles, the second resin particles are aggregated on the surface of the first aggregated particles. At this time, a release agent particle dispersion may be added to aggregate the second resin particles and the release agent particles on the surface of the first aggregated particles. Specifically, for example, in the first aggregated particle formation step, when the first aggregated particles reach the target particle size, the second resin particle dispersion is added to the first aggregated particle dispersion, and the second resin particles are heated below the glass transition temperature.

[0306] Then, by adjusting the pH of the dispersion liquid to, for example, a range of about 6.5 or more and 8.5 or less, the progress of aggregation is stopped.

[0307] In this way, second aggregated particles are obtained in which the second resin particles are attached to and aggregated on the surfaces of the first aggregated particles.

[0308] -Fusion and agglomeration process-

[0309] Next, the second aggregated particle dispersion in which the second aggregated particles are dispersed is heated, for example, to a temperature above the glass transition temperature of the first and second resin particles (for example, a temperature 10 to 30° C. higher than the glass transition temperature of the first and second resin particles) to fuse and aggregate the second aggregated particles to form colorant particles.

[0310] Through the above steps, toner particles are obtained.

[0311] In the above-described aggregation and coalescence method, the second aggregated particle forming step may not be performed, and the first aggregated particles may be fused and coalesced to form toner particles. Alternatively, the second aggregated particle forming step may be repeated a plurality of times.

[0312] Here, after the fusion and coalescence step is completed, the toner particles formed in the solution are subjected to a known washing step, a solid-liquid separation step, and a drying step to obtain dry toner particles.

[0313] As for the washing process, from the viewpoint of chargeability, replacement washing using ion exchange water can be fully implemented. In addition, the solid-liquid separation process is not particularly limited, but from the viewpoint of productivity, suction filtration, pressure filtration, etc. can be implemented. In addition, the drying process is not particularly limited to the method, but from the viewpoint of productivity, freeze drying, airflow drying, fluidized drying, vibration-type fluidized drying, etc. can be implemented.

[0314] Furthermore, in the method for producing a toner according to the embodiment of the present application, for example, an external additive may be added to and mixed with the toner particles obtained by the method for producing toner particles described above.

[0315] The mixing can be performed, for example, by a V-type blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed by using a vibration classifier, a wind classifier, etc.

[0316] <Electrostatic Image Developer Set>

[0317] The electrostatic image developer set of the present embodiment includes a white electrostatic image developer containing the white toner included in the toner set of the present embodiment, and a colored electrostatic image developer containing the colored toner included in the electrostatic image developing toner set of the present embodiment.

[0318] In the electrostatic image developer set of the present embodiment, each developer may be a single-component developer containing only the toner in the toner set of the present embodiment, or may be a two-component developer in which the toner and a carrier are mixed.

[0319] The carrier is not particularly limited, and known carriers may be used. Examples of the carrier include a coated carrier in which a coating resin is coated on the surface of a core material composed of magnetic powder; a magnetic powder dispersed carrier in which magnetic powder is dispersed and compounded in a matrix resin; a resin impregnated carrier in which a porous magnetic powder is impregnated with a resin; and the like.

[0320] Furthermore, the magnetic powder dispersed carrier and the resin impregnated carrier may be a carrier in which the constituent particles of the carrier are used as core materials and the core materials are coated with a coating resin.

[0321] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0322] Examples of the coating resin and matrix resin include styrene acrylic resin; polyolefin resins such as polyethylene and polypropylene; polyethylene or polyvinylidene resins such as polystyrene, (meth) acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; pure silicone resin composed of organic siloxane bonds or modified products thereof; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; amino resins such as urea formaldehyde resin; epoxy resin; and the like.

[0323] The coating resin and the matrix resin preferably contain a (meth)acrylic resin, more preferably contain 50% by mass or more of an alicyclic (meth)acrylic resin, and particularly preferably contain 80% by mass or more of a (meth)acrylic resin, based on the total mass of the resin.

[0324] Furthermore, other additives such as conductive particles may be contained in the coating resin and the matrix resin.

[0325] Examples of the conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0326] Here, in order to coat the coating resin on the surface of the core material, the coating resin and the coating layer formed by dissolving various additives in a suitable solvent as required can be enumerated to coat with a solution etc. As the solvent, there is no particular limitation, as long as the coating resin used, coating adaptability etc. are considered to be selected.

[0327] Specific resin coating methods include an immersion method in which the core material is immersed in a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the core material, a fluidized bed method in which the coating layer forming solution is sprayed while the core material is floated by flowing air, and a kneading coating method in which the core material of the carrier and the coating layer forming solution are mixed in a kneading coater and the solvent is removed.

[0328] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner:carrier=1:100 to 30:100, more preferably 3:100 to 20:100.

[0329] <Image Forming Apparatus, Image Forming Method>

[0330] An image forming apparatus and an image forming method according to the present embodiment will be described.

[0331] The image forming device of the present embodiment comprises: a first image forming unit, which comprises a first developing unit containing a white electrostatic charge image developer included in the developer group of the present embodiment, and forms a white image; a second image forming unit, which comprises a second developing unit containing a colored electrostatic charge image developer included in the developer group of the present embodiment, and forms a colored image based on the colored toner; a transfer unit, which transfers the white image and the colored image to the surface of a recording medium; and a fixing unit, which fixes the white image and the colored image transferred to the surface of the recording medium.

[0332] As the first or second image forming unit, the image forming device of the present embodiment may also be a type of image forming unit having each image forming unit, each of which has: an image retaining body, a charging unit for charging the surface of the image retaining body, an electrostatic charge image forming unit for forming an electrostatic charge image on the surface of the charged image retaining body, and a developing unit for developing the electrostatic charge image formed on the surface of the image retaining body as a colorant image using an electrostatic charge image developer.

[0333] In addition, the image forming device of the present embodiment may also be a type having the following components: an image retaining body, a charging unit for charging the surface of the image retaining body, an electrostatic charge image forming unit for forming an electrostatic charge image on the surface of the charged image retaining body, and a first and a second developing unit as the first or second image forming unit for developing the electrostatic charge image formed on the surface of the image retaining body as a colorant image using an electrostatic charge image developer.

[0334] In the image forming device of the present embodiment, an image forming method (the image forming method of the present embodiment) is implemented, and the image forming method has: a first image forming process for forming a white image based on the white colorant in the electrostatic charge image developing colorant group of the present embodiment, a second image forming process for forming a colored image based on the colored colorant in the electrostatic charge image developing colorant group of the present embodiment, a transfer process for transferring the white image and the colored image to a recording medium, and a fixing process for fixing the white image and the colored image on the recording medium.

[0335] The image forming device of the present embodiment applies the following well-known image forming devices: a device of a direct transfer method for directly transferring a colorant image (a white image or a colored image in the present embodiment) formed on the surface of an image retaining body onto a recording medium; a device of an intermediate transfer method for transferring a colorant image formed on the surface of an image retaining body to the surface of an intermediate transfer body for the first time, and for a second time transferring the colorant image transferred to the surface of the intermediate transfer body to the surface of a recording medium; a device having a cleaning unit for cleaning the surface of an image retaining body before charging after the toner image is transferred; a device having a de-staticizing unit for de-staticizing the surface of an image retaining body by irradiating de-staticizing light to the surface of the image retaining body before charging after the toner image is transferred.

[0336] In the case of an intermediate transfer type device, the transfer unit, for example, has a structure having the following components: an intermediate transfer body that transfers a colorant image on a surface, a primary transfer unit that transfers the colorant image formed on the surface of an image retaining body to the surface of the intermediate transfer body for the first time, and a secondary transfer unit that transfers the colorant image transferred to the surface of the intermediate transfer body for the second time to the surface of a recording medium.

[0337] In the image forming apparatus of the present embodiment, for example, the portion including the developing unit may be a cartridge structure (processing cartridge) that is detachable from the image forming apparatus. As the processing cartridge, for example, a processing cartridge having a developing unit that accommodates the electrostatic image developer set of the present embodiment is preferably used.

[0338] The image forming device of the present embodiment may also be an image forming device in which the white colorant included in the colorant group of the present embodiment is accommodated in a developing unit, and at least one selected from the yellow colorant, magenta colorant, cyan colorant and black colorant is accommodated in the developing unit.

[0339] The recording medium for recording images by the image forming apparatus (image forming method) of the present embodiment is not particularly limited, and known recording media can be used. For example, resin films or sheets, paper, etc. can be cited. As the purpose of the resin film or sheet, packaging, labels, packaging materials, promotional media, OHP sheets, etc. can be cited.

[0340] As the resin film or sheet, there can be mentioned polyolefin films or sheets such as polyethylene and polypropylene; polyester films or sheets such as polyethylene terephthalate and polybutylene terephthalate; polyamide films or sheets such as nylon; films or sheets such as polycarbonate, polystyrene, modified polystyrene, polyvinyl chloride, polyvinyl alcohol, polylactic acid, etc. These films or sheets may also be any of unstretched films or sheets, uniaxially stretched or biaxially stretched films or sheets. The resin film or sheet may also be any form of a single layer or multiple layers. The resin film or sheet may also be a film having a surface coating to assist in fixing the toner, or a film or sheet that has been subjected to corona treatment, ozone treatment, plasma treatment, flame treatment, glow discharge treatment, etc.

[0341] Examples of the lamination order of the recording medium, the color image, and the white image (hiding layer) include the following (a), (b), and (c).

[0342] Lamination order (a): from the side close to the viewer, transparent recording medium / colored image / white image (hidden layer).

[0343] Lamination order (b): from the side close to the viewer, colored image / transparent recording medium / white image (hidden layer).

[0344] Lamination order (c): from the side closest to the viewer, colored image / white image (hidden layer) / recording medium (regardless of transparency).

[0345] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the drawings will be described, and the description of other parts will be omitted.

[0346] Figure 1 1 is a schematic structural diagram showing an image forming apparatus according to the present embodiment, and is a diagram showing an image forming apparatus of a five-tandem system and an intermediate transfer system.

[0347] Figure 1 The image forming apparatus shown in the figure includes first to fifth image forming units 10Y, 10M, 10C, 10K, 10W (image forming units) of an electrophotographic method for outputting images of yellow (Y), magenta (M), cyan (C), black (K), and white (W) based on color separation image data. These image forming units (hereinafter sometimes referred to as "units") 10Y, 10M, 10C, 10K, 10W are arranged side by side at a predetermined distance from each other in the horizontal direction. These units 10Y, 10M, 10C, 10K, 10W may also be process cartridges that are attached to and detached from the image forming apparatus.

[0348] Below each unit 10Y, 10M, 10C, 10K, 10W, an intermediate transfer belt (an example of an intermediate transfer body) 20 is extended through each unit. The intermediate transfer belt 20 is wound around a driving roller 22, a supporting roller 23, and an opposing roller 24 that are in contact with the inner surface of the intermediate transfer belt 20, and travels in a direction from the first unit 10Y toward the fifth unit 10W. On the image holding surface side of the intermediate transfer belt 20, an intermediate transfer body cleaning device 21 is provided opposite to the driving roller 22.

[0349] Yellow, magenta, cyan, black and white toners contained in colorant boxes 8Y, 8M, 8C, 8K and 8W are respectively supplied to the developing devices (an example of developing units) 4Y, 4M, 4C, 4K and 4W of the units 10Y, 10M, 10C, 10K and 10W.

[0350] Since the first to fifth units 10Y, 10M, 10C, 10K, and 10W have the same structure, operation, and function, the first unit 10Y disposed upstream in the traveling direction of the intermediate transfer belt and forming a yellow image will be described as a representative.

[0351] The first unit 10Y has a photoreceptor 1Y that functions as an image holder. The following are arranged in order around the photoreceptor 1Y: a charging roller (an example of a charging unit) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic charge image forming unit) 3Y that exposes the charged surface using laser beams based on a color separation image signal to form an electrostatic charge image; a developing device (an example of a developing unit) 4Y that supplies toner to the electrostatic charge image to develop the electrostatic charge image; a primary transfer roller (an example of a primary transfer unit) 5Y that transfers the developed toner image to the intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning unit) 6Y that removes the toner remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0352] The primary transfer roller 5Y is arranged inside the intermediate transfer belt 20 and is set at a position opposite to the photosensitive body 1Y. A bias power supply (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5Y, 5M, 5C, 5K, and 5W of each unit. Each bias power supply changes the value of the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

[0353] Next, the operation of forming a yellow image in the first unit 10Y will be described.

[0354] First, before the operation, the surface of the photoreceptor 1Y is charged to a potential of -600 V to -800 V by the charging roller 2Y.

[0355] The photoreceptor 1Y has a conductivity (for example, a volume resistivity of 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate with a resistance of 100 Ωcm or less. The photosensitive layer is usually high in resistance (resistance of a general resin), but has a property that when irradiated with laser light, the resistivity of the portion irradiated with the laser light changes. Therefore, according to the image data for yellow sent from the control unit (not shown), the laser light is irradiated from the exposure device 3Y to the surface of the charged photoreceptor 1Y. As a result, an electrostatic charge image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

[0356] The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and is a so-called negative latent image. The negative latent image is formed as follows: the resistivity of the irradiated portion of the photosensitive layer is reduced by using the laser light from the exposure device 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, the charge of the portion not irradiated with the laser light remains, thereby forming the negative latent image.

[0357] The electrostatic charge image formed on the photoreceptor 1Y rotates to a predetermined development position as the photoreceptor 1Y travels. At the development position, the electrostatic charge image on the photoreceptor 1Y is developed into a toner image by the developing device 4Y and visualized.

[0358] The developing device 4Y contains, for example, an electrostatic charge image developer containing at least a yellow toner and a carrier. The yellow toner is frictionally charged by stirring inside the developing device 4Y, and is held on a developer roller (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y. Then, the surface of the photoreceptor 1Y passes through the developing device 4Y, whereby the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y that has been de-charged, and the latent image is developed using the yellow toner. The photoreceptor 1Y on which the yellow toner image is formed then travels at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0359] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roller 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, and the toner image on the photoreceptor 1Y is transferred to the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner, and is controlled by a control section (not shown) in the first unit 10Y to be, for example, +10 μA.

[0360] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0361] The primary transfer bias applied to the primary transfer rollers 5M, 5C, 5K, and 5W in the second unit 10M and thereafter is also controlled based on the first unit.

[0362] In this way, the intermediate transfer belt 20 to which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fifth units 10M, 10C, 10K, and 10W, and the toner images of the respective colors are multi-transferred in a superimposed manner.

[0363] The intermediate transfer belt 20 to which the five-color toner image has been multi-transferred by the first to fifth units reaches a secondary transfer section composed of the intermediate transfer belt 20, an opposing roller 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roller (an example of a secondary transfer unit) 26 disposed on the image holding surface side of the intermediate transfer belt 20. On the other hand, a recording paper (an example of a recording medium) P is fed to a gap between the secondary transfer roller 26 and the intermediate transfer belt 20 at a predetermined timing via a feeding mechanism, and a secondary transfer bias is applied to the opposing roller 24. The transfer bias applied at this time has a (-) polarity that is the same as the polarity (-) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, so that the toner image on the intermediate transfer belt 20 is transferred to the recording paper P. The secondary transfer bias at this time is determined based on the resistance detected by a resistance detection unit (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0364] Thereafter, the recording paper P is fed into a pressure-contact portion (nip portion) of a pair of fixing rollers in a fixing device (an example of a fixing unit) 28 , and the toner image is fixed on the recording paper P to form a fixed image.

[0365] Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copiers, printers, etc. Examples of the recording medium include OHP films, etc., in addition to the recording paper P.

[0366] In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is preferably smooth. For example, coated paper obtained by coating the surface of ordinary paper with a resin or the like, art paper for printing, etc. are preferably used.

[0367] The recording paper P on which the color image has been fixed is discharged toward the discharge portion, and a series of color image forming operations are completed.

[0368] <Process Cartridge / Toner Cartridge Set>

[0369] The process cartridge according to this embodiment will be described.

[0370] The processing box of this embodiment is a processing box that is installed and removed from an image forming device, and the processing box includes: a first developing unit, which accommodates the white electrostatic charge image developer in the electrostatic charge image developer group of this embodiment; and a second developing unit, which accommodates the colored electrostatic charge image developer in the electrostatic charge image developer group of this embodiment.

[0371] The process cartridge of this embodiment is not limited to the above-described structure, but may include a developing device and at least one of other units selected from, for example, an image holding member, a charging unit, an electrostatic image forming unit, and a transfer unit as required.

[0372] Hereinafter, an example of the process cartridge of the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the figure are described, and the description of other parts is omitted.

[0373] Figure 2 It is a schematic structural diagram showing a process cartridge according to this embodiment.

[0374] Figure 2 The processing box 200 shown is composed of, for example, a frame 117 having a mounting rail 116 and an opening 118 for exposure, which integrally combines and holds a photosensitive body 107 (an example of an image retaining body), a charging roller 108 (an example of a charging unit) arranged around the photosensitive body 107, a developing device 111 (an example of a developing unit), and a photosensitive body cleaning device 113 (an example of a cleaning unit) to form a box.

[0375] also, Figure 2 109 denotes an exposure device (an example of an electrostatic charge image forming unit), 112 denotes a transfer device (an example of a transfer unit), 115 denotes a fixing device (an example of a fixing unit), and 300 denotes recording paper (an example of a recording medium).

[0376] Next, the toner cartridge according to the present embodiment will be described.

[0377] The toner cartridge set of the present embodiment includes a white toner cartridge that contains the white toner contained in the toner cartridge set of the present embodiment and is attached and detached to the image forming apparatus, and a color toner cartridge that contains the color toner contained in the toner cartridge set of the present embodiment and is attached and detached to the image forming apparatus. The toner cartridge set contains the toner for replenishment to be supplied to the developing unit provided in the image forming apparatus.

[0378] also, Figure 2The image forming apparatus shown is an image forming apparatus having a structure for attaching and detaching toner cartridges 8Y, 8M, 8C, 8K, and 8W, and the developing devices 4Y, 4M, 4C, 4K, and 4W are connected to the toner cartridges corresponding to the respective developing devices (colors) through toner supply pipes not shown. In addition, when the toner contained in the toner cartridge becomes less, the toner cartridge is replaced.

[0379] [Example]

[0380] Hereinafter, the embodiments of the present invention will be described in detail by way of examples, but the embodiments of the present invention are not limited to these examples. In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0381] <Preparation of various dispersions>

[0382] (Preparation of Amorphous Polyester Resin Particle Dispersion (A1))

[0383] Bisphenol A ethylene oxide 2.2 mole adduct: 230 parts

[0384] Bisphenol A propylene oxide 2.2 mole adduct: 367 parts

[0385] Dimethyl terephthalate: 163 parts

[0386] Dimethyl fumarate: 12 parts

[0387] Dodecene succinic anhydride: 227 parts

[0388] ·Trimellitic anhydride: 20 parts

[0389] Tin dioctoate: 2.55 parts

[0390] 2.2 mol of bisphenol A ethylene oxide adduct, 2.2 mol of bisphenol A propylene oxide adduct, dimethyl terephthalate, and dodecene succinic anhydride were added to a container, and tin dioctoate was added. Then, the added samples were reacted at 235°C for 6 hours under a nitrogen flow, and dimethyl fumarate and trimellitic anhydride were added and reacted at 200°C for 1 hour. Furthermore, the temperature was raised to 220°C over 5 hours, and the monomers were polymerized under a pressure of 10 kPa to obtain a transparent light yellow amorphous polyester resin.

[0391] The prepared amorphous polyester resin had a weight average molecular weight (Mw) of 35,000, a number average molecular weight (Mn) of 8,000, and a glass transition temperature (Tg) of 59°C.

[0392] 100 parts by mass of the above-mentioned non-crystalline polyester resin was put into a disperser obtained by modifying Cavitron CD1010 manufactured by Eurotec Co., Ltd. into a high-temperature and high-pressure type.

[0393] Next, ion exchange water was added until the mass percentage concentration of the sample put into the disperser became 1 / 5, and the pH was adjusted to 8.5 with ammonia. The rotor speed was 60 Hz and the pressure was 5 kg / cm 2 The preparation was carried out by operating the disperser at a temperature of 140°C.

[0394] The volume average particle size of the resin particles in the preparation liquid was 130 nm. Deionized water was added to the preparation liquid to adjust the solid content to 10%, thereby obtaining an amorphous polyester resin particle dispersion (A1) in which particles of the amorphous polyester resin were dispersed.

[0395] (Preparation of Crystalline Polyester Resin Particle Dispersion Liquid (B1))

[0396] 1,10-Decanedicarboxylic acid: 260 parts

[0397] 1,6-Hexanediol: 167 parts

[0398] Dibutyltin oxide (catalyst): 0.3 parts

[0399] The above materials were added to a three-necked flask that was heated and dried, and the air in the three-necked flask was replaced with nitrogen to form an inert atmosphere. The mixture was stirred and refluxed at 180°C for 5 hours by mechanical stirring. Then, the temperature was gradually raised to 230°C under reduced pressure, stirred for 2 hours, and air-cooled when it became viscous to stop the reaction. In this way, a crystalline polyester resin with a weight average molecular weight of 12,500 and a melting temperature of 73°C was obtained. 90 parts of crystalline polyester resin, 1.8 parts of anionic surfactant (Tayca Power, manufactured by Tayca (KK), solid content 12%, sodium dodecylbenzene sulfonate) and 210 parts of ion exchange water were mixed, heated to 120°C, dispersed using a homogenizer (ULTRA TURRAX T50 manufactured by IKA), and then dispersed using a pressure jet type Gaulin homogenizer (Gaulin homogenizer) for 1 hour to obtain a resin particle dispersion in which resin particles with a volume average particle size of 195 nm were dispersed. Ion-exchanged water was added to the resin particle dispersion to adjust the solid content to 20%, thereby obtaining a crystalline polyester resin particle dispersion (B1).

[0400] (Preparation of Styrene Acrylic Resin Particle Dispersion Liquid (S1))

[0401] Styrene: 375 parts

[0402] n-Butyl acrylate: 25 parts

[0403] Acrylic acid: 2 parts

[0404] · Dodecanethiol: 24 parts

[0405] Carbon tetrabromide: 4 parts

[0406] The mixture obtained by mixing and dissolving the above materials is dispersed in a flask into a surfactant solution obtained by dissolving 6 parts of a nonionic surfactant (Nonipole 400 manufactured by Sanyo Chemical Industries) and 10 parts of an anionic surfactant (Tayca Power, manufactured by Tayca (Co., Ltd., solid content 12%, sodium dodecylbenzenesulfonate) in 550 parts of ion exchange water and emulsified. Next, while stirring in the flask, an aqueous solution obtained by dissolving 4 parts of ammonium persulfate in 50 parts of ion exchange water is added over 20 minutes. Next, after nitrogen substitution, the flask is heated in an oil bath while stirring until the contents reach 70°C, and the emulsion polymerization is continued at 70°C for 5 hours. In this way, a resin particle dispersion in which resin particles having a volume average particle size of 150 nm are dispersed is obtained. Ion exchange water is added to the resin particle dispersion and the solid content is adjusted to 10% to obtain a styrene acrylic resin particle dispersion (S1).

[0407] [Preparation of hybrid amorphous polyester resin particle dispersion]

[0408] (Preparation of Hybrid Amorphous Polyester Resin (C1))

[0409] A mixed liquid of the following vinyl resin monomer, a monomer having a substituent reactive with both the amorphous polyester resin and the vinyl resin, and a polymerization initiator is added to the dropping funnel.

[0410]

[0411] Separately, the following amorphous polyester resin monomer was placed in a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170° C. to dissolve.

[0412]

[0413] Under stirring, the mixed solution added to the dropping funnel was dripped into the four-necked flask over 90 minutes, aged for 60 minutes, and then unreacted monomers were removed under reduced pressure (8 kPa). Then, 0.4 parts by mass of Ti(OBu)4 as an esterification catalyst was added, the temperature was raised to 235°C, and the reaction was carried out under normal pressure (101.3 kPa) for 5 hours, and further under reduced pressure (8 kPa) for 1 hour.

[0414] Next, the mixture was cooled to 200° C., reacted under reduced pressure (20 kPa), and then subjected to solvent removal treatment to obtain a hybrid amorphous polyester resin (C1) modified with a vinyl resin.

[0415] The obtained hybrid amorphous polyester resin (C1) had a weight average molecular weight (Mw) of 24,000, an acid value of 16.2 mgKOH / g, a glass transition point (Tg) of 60°C, and a ratio (mass part of polyester resin segment / mass part of vinyl resin segment) of 90 / 10.

[0416] (Preparation of Hybrid Amorphous Polyester Resin Particle Dispersion (D1))

[0417] 100 parts by mass of the hybrid amorphous polyester resin (C1) was dissolved in 400 parts by mass of ethyl acetate (Kanto Chemical Co., Ltd.), and mixed with 600 parts by mass of a pre-prepared 0.26% sodium lauryl sulfate solution. While stirring the mixed solution, an ultrasonic dispersion treatment was performed for 30 minutes using an ultrasonic homogenizer US-150T (Nippon Seiki Seisaku-sho Co., Ltd.) at V-LEVEL 250μA. Ion exchange water was added to the resin particle dispersion to adjust the solid content to 16%, thereby obtaining a hybrid amorphous polyester resin particle dispersion (D1).

[0418] (Preparation of Colorant Dispersion Liquid (Cy1))

[0419] CI Pigment Blue 15:3 (produced by Dainichi Seika Industries): 70 parts

[0420] Anionic surfactant (Neogen RK manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part

[0421] Ion exchange water: 200 parts

[0422] The above materials were mixed and dispersed for 10 minutes using a homogenizer (ULTRA TURRAX T50 manufactured by IKA Corporation), and ion exchange water was added so that the solid content in the dispersion liquid became 20% to obtain a colorant dispersion liquid (Cy1) in which colorant particles having a volume average particle size of 190 nm were dispersed.

[0423] (Preparation of Anti-sticking Agent Particle Dispersion Liquid (W1))

[0424] Ester wax (manufactured by NOF Corporation, WEP-8, melting point 79°C): 100 parts

[0425] Anionic surfactant: 1 part

[0426] (Tayca Power, manufactured by Tayca Corporation, sodium dodecylbenzenesulfonate)

[0427] Ion exchange water: 350 parts

[0428] The above materials were mixed and heated to 100°C, dispersed using a homogenizer (ULTRA TURRAX T50 manufactured by IKA), and then dispersed using a pressure jet type Gaolin homogenizer to obtain an anti-sticking agent particle dispersion in which anti-sticking agent particles having a volume average particle size of 1000 nm were dispersed. Ion exchange water was added to the anti-sticking agent particle dispersion to adjust the solid content to 20% to prepare an anti-sticking agent particle dispersion (W1).

[0429] <Production of Colored Toner>

[0430] (Production of cyan toner (CT1))

[0431] -First Aggregate Particle Formation Step-

[0432] Ion exchange water: 200 parts

[0433] Colorant dispersion (Cy1): 15 parts

[0434] Anti-sticking agent particle dispersion (W1): 50 parts

[0435] Styrene acrylic resin particle dispersion (S1): 33 parts

[0436] Crystalline polyester resin particle dispersion (B1): 96 parts

[0437] Hybrid amorphous polyester resin particle dispersion (D1): 109 parts

[0438] The above materials were placed in a round stainless steel flask, 0.1N (0.1 mol / L) nitric acid was added, and after the pH was adjusted to 3.5, an aqueous solution of magnesium chloride obtained by dissolving 6 parts of magnesium chloride in 30 parts of ion exchange water was added. After being dispersed at 30°C using a homogenizer (ULTRA TURRAX T50 manufactured by IKA), the mixture was heated to 45°C in a heating oil bath and maintained until the volume average particle size became 4.5 μm.

[0439] -Second Aggregate Particle Formation Step-

[0440] Next, 5 parts of the styrene acrylic resin particle dispersion (S1) were added dropwise and kept for 30 minutes. 5 parts of the styrene acrylic resin particle dispersion (S1) were added every 30 minutes for a total of 4 times. Then, while continuing to stir, the pH was adjusted to 9.0 using a 1N sodium hydroxide aqueous solution.

[0441] -Fusion and agglomeration process-

[0442] Next, while continuing stirring, the temperature was raised to 85° C. at a temperature rise rate of 0.03° C. / min (first temperature rise), maintained at 85° C. for 3 hours, and then cooled to 30° C. at 15° C. / min (first cooling). Next, the temperature was raised to 85° C. at a temperature rise rate of 0.05° C. / min (second temperature rise), maintained for 30 minutes, and then cooled to 30° C. at 0.5° C. / min (second cooling).

[0443] Next, the solid content was filtered, washed with ion-exchanged water, and dried to obtain cyan toner particles (CT1) having a volume average particle size of 4.7 μm.

[0444] -Addition of external additives-

[0445] 100 parts of cyan toner particles (CT1) and 1.5 parts of hydrophobic silica (RY50 manufactured by Nippon Aerosil Co., Ltd.) were mixed and mixed at 10000 rpm for 30 seconds using a sample mill and sieved with a vibrating sieve having a mesh size of 45 μm to obtain cyan toner (CT1).

[0446] (Production of cyan toners (CT2) to (CT16), (CCT1) to (CCT4))

[0447] In the first aggregated particle forming step, except that the amounts of the release agent particle dispersion (W1), the styrene acrylic resin particle dispersion (S1), the crystalline polyester resin particle dispersion (B1), and the hybrid amorphous polyester resin particle dispersion (D1), and the heating rate were set to the amounts and heating rates described in Table 1, cyan toners (CT2) to (CT16) and (CCT1) to (CCT4) were obtained in the same manner as the cyan toner (CT1).

[0448] (Production of cyan toners (CT17) to (CT25))

[0449] After the toner particles are prepared, the toner particles are appropriately classified using a sieve, an ELBOW-JET classifier, etc., and fine powder is appropriately added if necessary to adjust the GSD. In the same manner as the cyan toner (CT1), cyan toners (CT17) to (CT25) are obtained.

[0450] (Production of cyan toner (CT26))

[0451] A cyan toner (CT26) was obtained in the same manner as in the cyan toner (CT1) except that the following components were used in the first aggregated particle forming step.

[0452] Ion exchange water: 200 parts

[0453] Colorant dispersion (Cy1): 15 parts

[0454] Anti-sticking agent particle dispersion (W1): 50 parts

[0455] Styrene acrylic resin particle dispersion (S1): 50 parts

[0456] Crystalline polyester resin particle dispersion (B1): 25 parts

[0457] Amorphous polyester resin particle dispersion (A1): 300 parts

[0458] Anionic surfactant (Dowfax (registered trademark) 2A1 manufactured by The Dow Chemical Company): 2.9 parts

[0459] (Production of cyan toner (CT27))

[0460] In the first aggregated particle forming step, the first aggregated particle forming step was carried out in the same manner as for the cyan toner (CT1), except that the amounts of the release agent particle dispersion (W1), the styrene acrylic resin particle dispersion (S1), the crystalline polyester resin particle dispersion (B1), and the hybrid amorphous polyester resin particle dispersion (D1) and the heating rates were those shown in Table 1.

[0461] Next, in the second aggregated particle forming step, the second aggregated particle forming step was carried out in the same manner as in the cyan toner (CT1), except that the styrene acrylic resin particle dispersion (S1) was replaced with the amorphous polyester resin particle dispersion (A1).

[0462] Then, a cyan toner (CT27) was obtained in the same manner as the cyan toner (CT1) except that the first aggregated particle forming step and the second aggregated particle forming step were performed as described above.

[0463] (Production of cyan toner (CT28))

[0464] In the first aggregated particle forming step, the first aggregated particle forming step was carried out in the same manner as for the cyan toner (CT1), except that the amounts of the release agent particle dispersion (W1), the crystalline polyester resin particle dispersion (B1), and the hybrid amorphous polyester resin particle dispersion (D1), and the heating rate were those shown in Table 1.

[0465] Next, in the second aggregated particle forming step, the second aggregated particle forming step was carried out in the same manner as in the cyan toner (CT1), except that the styrene acrylic resin particle dispersion (S1) was replaced with the amorphous polyester resin particle dispersion (A1).

[0466] Then, a cyan toner (CT28) was obtained in the same manner as the cyan toner (CT1) except that the first aggregated particle forming step and the second aggregated particle forming step were performed as described above.

[0467] <Production of White Toner>

[0468] (Preparation of White Toner (WT1))

[0469] -Preparation of toner particle forming materials-

[0470] As toner particle forming materials, the following materials were prepared.

[0471] Polyester resin (polyester resin synthesized using a tin catalyst with bisphenol A 2 mol propylene oxide adduct / 2 mol ethylene oxide adduct, terephthalic acid, and trimellitic acid as main components): 51.1 parts

[0472] Styrene acrylic resin (resin prepared by polymerizing styrene and butyl acrylate under cumene reflux): 6.4 parts

[0473] White colorant (titanium oxide particles (manufactured by Ishihara Sangyo Co., Ltd., product name: CR-60-2): 25 parts

[0474] Anti-adhesive agent (polypropylene; Mitsui Chemicals, Inc., Mitsui HI-WAX NP055): 2 parts

[0475] -Mixing process-

[0476] The above toner forming materials were mixed using a Henschel mixer and then Figure 3 The twin-screw extruder (ie, continuous kneading machine) shown above was used to perform kneading under the following conditions: The rotation speed of the screw was set to 500 rpm.

[0477] Feeding section (blocks 12A and 12B) set temperature: 20°C

[0478] Kneading section 1 mixing setting temperature (blocks 12C to 12E): 100°C

[0479] Kneading section 2 mixing setting temperature (blocks 12F to 12J): 110°C

[0480] · Amount of aqueous medium (distilled water) added (relative to 100 parts of raw material supply): 1.5 parts

[0481] During the kneading under the above conditions, the temperature of the kneaded material at the discharge port (discharge port 18) of the screw extruder 11 was 120°C.

[0482] The steel was rapidly cooled by a flat plate clamping cooling belt with -5°C salt water and 2°C cold water passing through the rollers inside, and then crushed by a hammer mill. The rapid cooling rate was confirmed by changing the speed of the cooling belt, but the average temperature drop rate was 10°C / sec.

[0483] The kneaded product obtained in the second kneading step was then pulverized by a pulverizer (AFG400) with a built-in coarse powder classifier to obtain pulverized particles, and then classified by an inertial classifier to remove fine powder and coarse powder to obtain white toner particles (WT1) with a volume average particle size of 6.0 μm.

[0484] -Addition of external additives-

[0485] To the obtained white colorant particles (W1), 40 parts of a titanium compound treated with isobutyltrimethoxysilane and 1.5 parts of spherical silica treated with hexamethyldisilazane having an average particle size of 130 nm were added based on 100 parts of metatitanic acid, and the mixture was mixed (external addition) for 10 minutes using a Henschel mixer, and then sieved at 45 μm using a wind classifier (HI-BOLTER) to obtain a white colorant (WT1).

[0486] (Production of white toners (WT2) to (WT11))

[0487] White toners (WT2) to (WT11) were obtained in the same manner as in the white toner (WT1), except that the release agent, the styrene acrylic resin, and the polyester resin were used in the amounts shown in Table 1.

[0488] (Production of white toners (WT12) to (WT20))

[0489] After the toner particles are prepared, the toner particles are appropriately classified using a sieve, an ELBOW-JET classifier, etc., and fine powder is appropriately added if necessary to adjust the GSD. Toners (WT12) to (WT20) are obtained in the same manner as the white toner (WT1).

[0490] <Examples 1 to 34, Comparative Examples 1 to 4>

[0491] A toner set of a cyan toner and a white toner shown in Table 1 was used as a toner set in each example.

[0492] Then, the cyan toner in the toner set of each example and the carrier (CA) obtained by the method described below were placed in a V-type mixer at a mass ratio (toner / carrier) of 5 / 95 and stirred for 20 minutes to obtain a cyan developer of each example.

[0493] On the other hand, the white toner in the toner set of each example and the carrier (CB) obtained by the method described below were put into a V-type mixer at a mass ratio (toner / carrier) of 8 / 92 and stirred for 20 minutes to obtain a white developer of each example.

[0494] Then, the obtained cyan developer and white developer were set as a developer set in each example.

[0495] -Preparation of vector (CA)-

[0496] After 500 parts of spherical magnetite powder particles (volume average particle size 0.55 μm) were stirred with a Henschel mixer, 5 parts of a titanate coupling agent were added, the temperature was raised to 100°C, and the mixture was stirred for 30 minutes. Next, 6.25 parts of phenol, 9.25 parts of 35% formalin, 500 parts of magnetite particles treated with a titanate coupling agent, 6.25 parts of 25% ammonia water, and 425 parts of water were added to a four-necked flask and stirred, and the mixture was reacted at 85°C for 120 minutes while stirring. Next, the mixture was cooled to 25°C, 500 parts of water were added, the supernatant was removed, and the precipitate was washed with water. The washed precipitate was dried by heating under reduced pressure to obtain a carrier (CA) with an average particle size of 35 μm.

[0497] -Preparation of Carrier (CB)-

[0498] A mixed solution prepared by dissolving and mixing 2.0 parts of cyclohexyl methacrylate resin (weight average molecular weight: 150,000), 0.6 parts of carbon black (VXC72) and 0.3 parts by mass of melamine beads (Epostar S) in 10 parts of toluene was applied to 100 parts of ferrite cores having a volume average particle size of 35 μm using a kneading device to obtain a carrier (CB).

[0499] <Evaluation>

[0500] The following evaluations were performed using the developer sets of each example.

[0501] First, as an image forming apparatus, the developer of the developer set of each example was placed in a production printer "Iridesse Production Press (Fujifilm Business Innovation Co., Ltd.) modified machine".

[0502] Then, the following evaluation was performed using this image forming apparatus.

[0503] (Color quality evaluation of colored images)

[0504] In a normal temperature and humidity environment (25°C, 50% RH), a white toner of 8 g / m was used on a transparent OHP sheet. 2 , Cyan toner 4g / m 2The image of the letter "A" (20 pt) of 5×5 cm square was drawn in the order of approaching the OHP sheet and in the order of a cyan image and a white image.

[0505] The edge of the "A" image in the image was observed visually and with a 2000-fold optical microscope (Keyence: VHX-2000) to observe whether the color of the underlying cyan image could be recognized, and the results were evaluated based on the following criteria.

[0506] In addition, A, B, and C were qualified. Table 2 shows the obtained evaluation results.

[0507] However, this evaluation was carried out in Examples 1-22, 32-34, and Comparative Examples 1-4.

[0508] A: The color of the cyan image cannot be recognized at all.

[0509] B+: Although some slight cyan color can be seen when observing with a magnifying glass, this is a level without any problems.

[0510] B: Although a slight bluish-green image can be seen when observing with a magnifying glass, this is a level without any problem.

[0511] C: Although the color of the cyan image is slightly visible, it is a level without any problem.

[0512] D: A cyan image can be visually confirmed, which is a level that is problematic in practical use.

[0513] E: A cyan image can be clearly seen, which is a level that is problematic in practical use.

[0514] (Evaluation of peeling of colored image)

[0515] The image obtained by the color formation evaluation of the colored image was rubbed back and forth 10 times with cotton.

[0516] Then, the image defect after rubbing the image was evaluated. The evaluation was performed according to the following evaluation criteria. A, B, and C were considered acceptable. The obtained evaluation results are shown in Table 2.

[0517] However, this evaluation was carried out in Examples 1-22, 32-34 and Comparative Examples 1-4.

[0518] A: No image roughness at all.

[0519] B+: Although some slight image roughness is observed under a magnifying glass, the grade is not problematic.

[0520] B: Although slight image roughness was observed with a magnifying glass, it was a level without any problem.

[0521] C: Although slight image roughness was visually confirmed, the grade was not problematic.

[0522] D: The image is rough and can be visually confirmed, which is a level that is problematic in practical use.

[0523] E: A level where image roughness is noticeably produced and is problematic in practical use.

[0524] (Evaluation of peeling of white image on embossed paper)

[0525] Under normal temperature and humidity (25°C, 50% RH) environment, on A4 size embossed paper "Leathack66, 302g / m 2 ", with a white toner of 8g / m 2 , cyan toner is 4g / m 2 The load is 100%, starting from the side close to the paper, and a 1-inch square (2.54cm×2.54cm) image is formed in the order of a white image and a cyan image, and the wrinkle evaluation is performed. The so-called wrinkle evaluation is as follows: on the basis of gently bending the sample in half, a roller with an outer diameter of 60mm with a load of about 500g is rotated twice at a constant speed, and the fold of the fixed image is gently wiped with cotton yarn, and the width of the missing part of the image is measured. The evaluation is carried out according to the following evaluation criteria.

[0526] In addition, A, B, and C were qualified. Table 2 shows the obtained evaluation results.

[0527] Here, this evaluation was carried out in Example 1 and Examples 23-31.

[0528] A: No image loss

[0529] B: The image loss is less than 0.2 (mm)

[0530] C: The image loss width is greater than 0.2 (mm) and less than 0.5 (mm)

[0531] D: The image loss width is greater than 0.5 (mm) and less than 1.0 (mm)

[0532] E: The image loss is greater than 1.0 (mm)

[0533] (Evaluation of peeling of colored image on embossed paper)

[0534] The image obtained by the evaluation of peeling of the white image was reciprocally rubbed 10 times with cotton.

[0535] Then, the image defect after the image was erased was evaluated. The evaluation was performed according to the following evaluation criteria.

[0536] In addition, A, B, and C were qualified. Table 2 shows the obtained evaluation results.

[0537] However, this evaluation was also carried out in Example 1 and Examples 23-31.

[0538] A: No image roughness at all.

[0539] B: Slight image roughness was observed when observed with a magnifying glass, but the level was not problematic.

[0540] C: A level where slight image roughness was visually confirmed but no problem was found.

[0541] D: The image is visually rough and is a level that is problematic in practical use.

[0542] E: Image roughness is noticeably generated, which is a level that is problematic in practical use.

[0543] In addition, Table 2 shows the following characteristics of the white toner and the color toner (cyan toner in this embodiment).

[0544] Content of vinyl resin relative to color toner particles: mass % (denoted as "StAc ratio CS" in Table 2)

[0545] Content of polyester resin relative to color toner particles: mass % (denoted as "PES ratio CP" in Table 2)

[0546] Mass ratio C of the polyester resin to the vinyl resin in the colored toner particles (denoted as "PES / StAc ratio C")

[0547] Content of vinyl resin relative to white toner particles: mass % (denoted as "StAc ratio WS" in Table 2)

[0548] Content of polyester resin relative to white toner particles: mass % (denoted as "PES ratio WP" in Table 2)

[0549] Mass ratio W of the polyester resin to the vinyl resin in the white toner particles (represented as "PES / StAc ratio W" in Table 2)

[0550] When observing the cross section of the colored toner particles, the polyester resin domain has the maximum diameter (denoted as "PES_Dmax" in Table 2)

[0551] The area ratio of the polyester resin present in the inner region of the colored toner particle when the cross section of the colored toner particle is observed (represented as "inner PES area ratio" in Table 2)

[0552] The area ratio a of the release agent when observing the cross section of the white toner particle (denoted as "WAX_area ratio a" in Table 2)

[0553] When the cross section of the colored toner particles is observed, the area ratio b of the release agent (represented as "WAX_area ratio b" in Table 2)

[0554] Lower number particle size distribution index of white toner (denoted as "lower GSDw" in Table 2)

[0555] ·Lower number particle size distribution index of colored toner (represented as "lower GSDc" in Table 2) [Table 1-1]

[0556]

[0557] [Table 1-2]

[0558] Styrene acrylic resin Polyester resin PES / StAc ratio (C) Anti-sticking agent WT1 6.4 51.1 8 2 WT2 11.1 46.4 4.2 2 WT3 10.6 46.9 4.4 2 WT4 9.6 47.9 5 2 WT5 5.8 51.8 9 2 WT6 5.0 52.5 10.6 2 WT7 4.8 52.7 10.9 2 WT8 6.4 51.1 8.0 0.3 WT9 6.4 51.1 8.0 0.4 WT10 6.4 51.1 8.0 5.0 WT11 6.4 51.1 8.0 6.0

[0559] [Table 2-1]

[0560]

[0561] [Table 2-2]

[0562]

[0563] [Table 2-3]

[0564]

[0565] According to the above results, it can be seen that in this embodiment, compared with the comparative example, the color quality of the colored image is high, and image roughness is not easily produced in the friction evaluation of the image. Therefore, the image with a colored image on a white image has high color quality, and the peeling of the colored image is suppressed.

[0566] (Note) (((1)))

[0568] A toner set for electrostatic image development, comprising:

[0569] A white toner having white toner particles including a polyester resin and a white colorant; and

[0570] a non-white colored toner, the non-white colored toner having colored toner particles containing a vinyl resin, a polyester resin and a colored colorant,

[0571] In the colored toner particles, a mass ratio C of the polyester resin to the vinyl resin is 0.7 or more and 10 or less.

[0572] When observing a cross section of the colored toner particles, the polyester resin forms domains having a maximum diameter of 100 nm or more and 1 μm or less. (((2)))

[0574] The electrostatic image developing toner set according to (((1))), wherein:

[0575] A mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is 2 or more and 6 or less. (((3)))

[0577] The electrostatic charge image developing toner set according to (((1))) or (((2))), wherein:

[0578] When observing a cross section of the colored toner particles, the polyester resin forms domains having a maximum diameter of 100 nm or more and 600 nm or less. (((4)))

[0580] The electrostatic charge image developing toner set according to any one of (((1))) to (((3))), wherein:

[0581] The white toner particles include a vinyl resin. (((5)))

[0583] The electrostatic image developing toner set according to (((4))), wherein:

[0584] The relationship between the mass ratio W of the polyester resin to the vinyl resin in the white toner particles and the mass ratio C of the polyester resin to the vinyl resin in the color toner particles satisfies -0.6≤WC≤5.6. (((6)))

[0586] The electrostatic image developing toner set according to (((5))), wherein:

[0587] The relationship between the mass ratio W of the polyester resin to the vinyl resin in the white toner particles and the mass ratio C of the polyester resin to the vinyl resin in the color toner particles satisfies 0≤WC≤4. (((7)))

[0589] The electrostatic charge image developing toner set according to any one of (((1))) to (((6))), wherein:

[0590] When observing a cross section of the colored toner particle, the area ratio of the polyester resin present in the inner region of the colored toner particle is 3% or more and 25% or less. (((8)))

[0592] The electrostatic charge image developing toner set according to any one of (((1))) to (((7))), wherein:

[0593] The white toner particles and the colored toner particles contain a release agent,

[0594] The relationship between the area ratio a of the release agent when observing the cross section of the white toner particle and the area ratio b of the release agent when observing the cross section of the color toner particle satisfies 0.03≤a / b≤0.5. (((9)))

[0596] The electrostatic charge image developing toner set according to any one of (((1))) to (((8))), wherein:

[0597] The white toner has a lower number size distribution index (lower GSDw) of 1.2 or more and 1.54 or less. (((10)))

[0599] The electrostatic charge image developing toner set according to any one of (((1))) to (((9))), wherein:

[0600] The white toner has a lower number size distribution index (lower GSDw) of 1.2 or more and 1.4 or less. (((11)))

[0602] The electrostatic charge image developing toner set according to any one of (((1))) to (((10))), wherein

[0603] The ratio (lower GSDw / lower GSDc) of the lower number particle size distribution index (lower GSDw) of the white toner and the lower number particle size distribution index (lower GSDc) of the color toner is 1.0 or more and 1.4 or less. (((12)))

[0605] An electrostatic charge image developer set, comprising:

[0606] a white electrostatic charge image developer containing the white toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((11))); and

[0607] A colored electrostatic image developer containing the colored toner included in the electrostatic image developing toner set described in any one of (((1))) to (((11))). (((13)))

[0609] A toner cartridge set, comprising:

[0610] A white toner cartridge that contains the white toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((11))) and is attachable to and detachable from an image forming apparatus; and

[0611] A color toner cartridge that contains the color toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((11))) and is attachable to and detachable from an image forming apparatus. (((14)))

[0613] A processing box, comprising:

[0614] a first developing unit, the first developing unit accommodating the white electrostatic charge image developer included in the electrostatic charge image developer group described in (((12))); and

[0615] a second developing unit, the second developing unit containing the colored electrostatic charge image developer included in the electrostatic charge image developer group (((12))),

[0616] The process cartridge is attachable to and detachable from the image forming apparatus. (((15)))

[0618] An image forming device, comprising:

[0619] a first image forming unit including a first developing unit containing the white electrostatic image developer included in the electrostatic image developer group described in (((12))), and forming a white image based on the white toner;

[0620] a second image forming unit including a second developing unit containing the colored electrostatic image developer included in the electrostatic image developer group described in (((12))), and forming a colored image based on the colored toner;

[0621] a transfer unit that transfers the white image and the colored image to a surface of a recording medium; and

[0622] A fixing unit fixes the white image and the color image transferred to the surface of the recording medium. (((16)))

[0624] An image forming method, comprising:

[0625] a first image forming step of forming a white image based on the white toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((11)));

[0626] a second image forming step of forming a color image based on the color toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((11)));

[0627] a transfer step of transferring the white image and the colored image to a surface of a recording medium; and

[0628] The fixing step fixes the white image and the color image transferred to the surface of the recording medium.

[0629] According to (((1))), a colorant group for electrostatic charge image development is provided, which comprises: a white colorant, the white colorant having white colorant particles containing a polyester resin and a white colorant; and a colored colorant other than white, the colored colorant other than white having colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, wherein the color formation of an image having a colored image on a white image is high and peeling of the colored image can be suppressed compared with the following situation: the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles is less than 0.7 or exceeds 10, or when observing the cross section of the colored colorant particles, the polyester resin forms a domain with a maximum diameter of less than 100 nm or greater than 1 μm.

[0630] According to (((2))), a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image, and can suppress the peeling of the colored image, compared with the case where the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles is less than 2 or greater than 6.

[0631] According to (((3))), a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image, and can suppress peeling of the colored image, compared with a case where the polyester resin forms a domain with a maximum diameter less than 100 nm or greater than 600 nm when observing the cross section of the colored colorant particles.

[0632] According to (((4))), a toner set for electrostatic image development is provided, which has high color formation of an image having a colored image on a white image and can suppress peeling of the colored image, compared with a case where white toner particles contain only a polyester resin as a binder resin.

[0633] According to (((5))), a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image and can suppress peeling of the colored image, compared with a case where the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white colorant particles and the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles does not satisfy -0.6≤WC≤5.6.

[0634] According to (((6))), a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image and can suppress peeling of the colored image, compared with a case where the relationship between the mass ratio W of the polyester resin to the vinyl resin in the white colorant particles and the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles does not satisfy 0≤WC≤4.

[0635] According to (((7))), a colorant group for electrostatic charge image development is provided, which has high color formation of an image having a colored image on a white image, and can suppress peeling of the colored image, compared with a case where the area ratio of the polyester resin present in the internal region of the colored colorant particles is less than 3% or exceeds 25% when observing the cross-section of the colored colorant particles.

[0636] According to (((8))), a colorant group for electrostatic charge image development is provided, in which the color formation of an image having a colored image on a white image is high, and peeling of the colored image can be suppressed, compared with a case where the relationship between the area ratio a of the anti-sticking agent when observing the cross section of the white colorant particle and the area ratio b of the anti-sticking agent when observing the cross section of the colored colorant particle does not satisfy 0.03≤a / b≤0.5.

[0637] According to (((9))), there is provided a toner set for electrostatic image development, which can suppress peeling of a white image compared with a case where the lower number size distribution index (lower GSDw) of the white toner is less than 1.2 or exceeds 1.54.

[0638] According to (((10))), there is provided a toner set for electrostatic image development, which can suppress peeling of a white image compared with a case where the lower number size distribution index (lower GSDw) of the white toner is less than 1.2 or exceeds 1.4.

[0639] According to (((11))), a colorant group for developing electrostatic charge images is provided, which has high color formation of an image having a colored image on a white image, and can suppress flaking of the white image, compared with a case where the ratio (lower GSDw / lower GSDc) of the lower side number particle size distribution index (lower GSDw) of the white colorant to the lower side number particle size distribution index (lower GSDc) is less than 1.0 or exceeds 1.4.

[0640] According to (((12)))(((13))), (((14))), (((15))) or (((16))), there is provided an electrostatic image developer group, a colorant box group, a process box, an image forming apparatus or an image forming method, wherein the color formation of an image having a colored image on a white image is high and peeling of the colored image can be suppressed compared to a case where the electrostatic image developing colorant group is applied, wherein the electrostatic image developing colorant group comprises: a white toner having white toner particles comprising a polyester resin and a white colorant; and a colored toner other than white, wherein the colored toner other than white has colored toner particles comprising a vinyl resin, a polyester resin and a colored colorant, wherein the mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is less than 0.7 or exceeds 10, or when observing a cross section of the colored toner particles, the polyester resin forms a domain having a maximum diameter of less than 100 nm or exceeding 1 μm.

Claims

1. A toner set for electrostatic image development, characterized in that: have: A white toner having white toner particles including a polyester resin and a white colorant; and a non-white colored toner, the non-white colored toner having colored toner particles containing a vinyl resin, a polyester resin and a colored colorant, In the colored toner particles, a mass ratio C of the polyester resin to the vinyl resin is 0.7 or more and 10 or less. When observing a cross section of the colored toner particles, the polyester resin forms domains having a maximum diameter of 100 nm or more and 1 μm or less.

2. The electrostatic image developing toner set according to claim 1, wherein: A mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is 2 or more and 6 or less.

3. The electrostatic image developing toner set according to claim 1 or 2, wherein: When observing a cross section of the colored toner particles, the polyester resin forms domains having a maximum diameter of 100 nm or more and 600 nm or less.

4. The electrostatic charge image developing toner set according to any one of claims 1 to 3, wherein The white toner particles include a vinyl resin.

5. The electrostatic image developing toner set according to claim 4, wherein: The relationship between the mass ratio W of the polyester resin to the vinyl resin in the white toner particles and the mass ratio C of the polyester resin to the vinyl resin in the color toner particles satisfies -0.6≤WC≤5.

6.

6. The electrostatic image developing toner set according to claim 5, wherein: The relationship between the mass ratio W of the polyester resin to the vinyl resin in the white toner particles and the mass ratio C of the polyester resin to the vinyl resin in the color toner particles satisfies 0≤WC≤4.

7. The electrostatic charge image developing toner set according to any one of claims 1 to 6, wherein: When observing a cross section of the colored toner particle, the area ratio of the polyester resin present in the inner region of the colored toner particle is 3% or more and 25% or less.

8. The electrostatic image developing toner set according to any one of claims 1 to 7, wherein The white toner particles and the colored toner particles contain a release agent, The relationship between the area ratio a of the release agent when observing the cross section of the white toner particle and the area ratio b of the release agent when observing the cross section of the color toner particle satisfies 0.03≤a / b≤0.

5.

9. The electrostatic image developing toner set according to any one of claims 1 to 8, wherein The white toner has a lower number size distribution index (lower GSDw) of 1.2 or more and 1.54 or less.

10. The electrostatic charge image developing toner set according to any one of claims 1 to 9, wherein The white toner has a lower number size distribution index (lower GSDw) of 1.2 or more and 1.4 or less.

11. The electrostatic image developing toner set according to any one of claims 1 to 10, wherein: The ratio (lower GSDw / lower GSDc) of the lower number particle size distribution index (lower GSDw) of the white toner and the lower number particle size distribution index (lower GSDc) of the color toner is 1.0 or more and 1.4 or less.

12. An electrostatic charge image developer set, characterized in that: Include: a white electrostatic image developer, the white electrostatic image developer containing the white toner possessed by the electrostatic image developing toner set according to any one of claims 1 to 11; as well as A colored electrostatic image developer comprising the colored toner included in the electrostatic image developing toner set according to any one of claims 1 to 11.

13. A toner cartridge set, characterized in that: Include: a white toner cartridge, the white toner cartridge containing the white toner included in the electrostatic charge image developing toner set according to any one of claims 1 to 11, and being attachable to and detachable from an image forming apparatus; as well as A color toner cartridge that contains the color toner included in the electrostatic image developing toner set according to any one of claims 1 to 11 and is attachable to and detachable from an image forming apparatus.

14. A processing box, characterized in that: have: a first developing unit, the first developing unit containing the white electrostatic charge image developer included in the electrostatic charge image developer set according to claim 12; and a second developing unit, the second developing unit containing the colored electrostatic image developer included in the electrostatic image developer set according to claim 12, The process cartridge is attachable to and detachable from the image forming apparatus.

15. An image forming device, characterized in that: have: a first image forming unit including a first developing unit containing the white electrostatic image developer included in the electrostatic image developer set according to claim 12, and forming a white image based on the white toner; a second image forming unit including a second developing unit containing the colored electrostatic image developer included in the electrostatic image developer set according to claim 12, and forming a colored image based on the colored toner; a transfer unit, wherein the transfer unit transfers the white image and the colored image to a surface of a recording medium; as well as A fixing unit fixes the white image and the color image transferred to the surface of the recording medium.

16. An image forming method, characterized in that: have: a first image forming step of forming a white image using the white toner included in the electrostatic charge image developing toner set according to any one of claims 1 to 11; a second image forming step of forming a color image based on the color toner included in the electrostatic charge image developing toner set according to any one of claims 1 to 11; A transfer step of transferring the white image and the colored image to a surface of a recording medium; as well as The fixing step fixes the white image and the color image transferred to the surface of the recording medium.

Images