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, the mass ratio C of the polyester resin to the vinyl resin in the colored toner particles being 0.7-10 inclusive.

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 processing 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 for the purpose of forming a colored image on a colored recording medium or a transmissive recording medium.

[0003] For example, Japanese Patent Gazette No. 7163574 proposes "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 mother particle, and the colorant mother particle has at least a plurality of protrusions arranged on its surface."

[0004] For example, in Japanese Patent Gazette No. 2020-79868, "an image forming method is proposed, which includes: an electrostatic latent image forming process, forming an electrostatic latent image on an electrostatic latent image carrier; a developing process, using a colorant containing a colorant masterbatch containing a binding resin, a bright pigment, a white pigment and a release agent to develop the electrostatic latent image to form a white colorant image; a color colorant image developing process, forming a color colorant image from a color colorant; a transfer process, transferring the colorant image to a recording medium; and a fixing process, fixing the transfer image transferred to the recording medium, wherein the white colorant image is formed on the recording medium side than the color colorant image."

[0005] In addition, in Japanese Patent Gazette No. 2018-97016, it is proposed that there is "a colorant group comprising: a white colorant, the white colorant includes white colorant particles containing white coloring particles; and at least one selected from a colored colorant and a transparent colorant, the colored colorant includes colored colorant particles containing colored coloring particles, the transparent colorant includes transparent colorant particles, the average roundness of the white colorant particles is smaller than the average roundness of any one of the colored colorant particles and the transparent colorant particles, and the small diameter side number particle size distribution index of the white colorant particles is larger than the small diameter side number particle size distribution index of any one of the colored colorant particles and the transparent colorant particles.". Summary of the invention

[0006] The object of the present invention is to provide a colorant group for electrostatic charge image development, which has high color formation of an image having a colored image on a white image and suppresses the peeling of the colored image compared with the following electrostatic charge image development colorant group: the electrostatic charge image development colorant group comprises: a white colorant, the white colorant has white colorant particles containing a polyester resin and a white colorant; and a colored colorant other than white, the colored colorant has colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, and 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.

[0007] According to a first embodiment of the present invention, 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 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 0.7 and less than 10.

[0008] 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.

[0009] According to a third aspect of the present invention, in the electrostatic image developing toner set according to the first aspect, a dispersion value P parameter of the white colorant measured by a division method on a cross section of the white toner particle is 0.85 or more and 1.00 or less.

[0010] According to a fourth aspect of the present invention, in the electrostatic image developing toner set according to the third aspect, a dispersion value P parameter of the white colorant measured by a division method on a cross section of the white toner particle is 0.90 or more and 1.00 or less.

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

[0012] 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 -0.6≤WC≤5.6.

[0013] According to the seventh embodiment of the present invention, in the electrostatic charge image developing colorant group involved in the sixth 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 an eighth aspect of the present invention, in the electrostatic image developing toner set according to any one of the first to seventh aspects, the content of the white colorant relative to the white toner particles is 20 mass % or more and 60 mass % or less.

[0015] According to the ninth scheme of the present invention, in the electrostatic charge image developing colorant group involved in the first scheme, when observing the cross-section of the white colorant particles, the area ratio of the white colorant is greater than 10% and less than 50%, and the number average particle size of the white colorant is greater than 0.23 μm and less than 0.45 μm.

[0016] According to the tenth embodiment of the present invention, in the electrostatic charge image developing colorant group involved in the ninth embodiment, when observing the cross-section of the white colorant particles, the area ratio of the white colorant is greater than 20% and less than 50%, and the number average particle size of the white colorant is greater than 0.23 μm and less than 0.30 μm.

[0017] According to the eleventh aspect of the present invention, in the electrostatic image developing toner set according to the ninth aspect, when observing the cross section of the white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to all white colorants is 30% by number or less.

[0018] According to a twelfth aspect of the present invention, in the electrostatic image developing toner set according to the eleventh aspect, when observing a cross section of the white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to all white colorants is 20% by number or less.

[0019] According to the thirteenth embodiment 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 involved in any one of the first to twelfth embodiments; 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 involved in any one of the first to twelfth embodiments.

[0020] According to the fourteenth 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 involved in any one of the first to twelfth 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 involved in any one of the first to twelfth embodiments, and is installed and removed from the image forming device.

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

[0022] According to the sixteenth 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 for storing the white electrostatic charge image developer contained in the electrostatic charge image developer group involved in the thirteenth aspect, and forming a white image using the white colorant; a second image forming unit, the second image forming unit comprising a second developing unit for storing the colored electrostatic charge image developer contained in the electrostatic charge image developer group involved in the thirteenth aspect, and forming a colored image using 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 seventeenth aspect of the present invention, an image forming method is provided, which comprises: a first image forming process, forming a white image using the white colorant possessed by the electrostatic charge image developing colorant group involved in any one of the first to twelfth aspects; a second image forming process, forming a colored image using the colored colorant possessed by the electrostatic charge image developing colorant group involved in any one of the first to twelfth 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 has high color formation of an image having a colored image on a white image and suppresses peeling of the colored image compared with the following electrostatic charge image development colorant group: the electrostatic charge image development colorant group 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 having colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, and 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.

[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 suppresses the peeling of the colored image compared to the following situation: the mass ratio C of the polyester resin to the vinyl resin in the colored toner 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 suppresses the peeling of the colored image compared with the following situation: the dispersion value P parameter of the white colorant measured by the division method on the cross section of the white colorant particle is less than 0.85 or exceeds 1.00.

[0028] According to the fourth 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 suppresses the peeling of the colored image compared with the following situation: the dispersion value P parameter of the white colorant measured by the division method on the cross section of the white colorant particles is less than 0.90 or exceeds 1.00.

[0029] According to the fifth aspect, there is provided an electrostatic image developing toner set which has a high degree of color formation of an image having a color image on a white image and suppresses peeling of the color image compared with a case where white toner particles contain only a polyester resin as a binder resin.

[0030] According to the sixth scheme, a colorant group for electrostatic charge image development is provided, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the colored image compared to the following situation: 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.

[0031] According to the seventh scheme, a colorant group for electrostatic charge image development is provided, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the colored image compared to the following situation: 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.

[0032] According to the eighth aspect, there is provided a toner set for electrostatic image development, which has high color formation of an image having a colored image on a white image and suppresses peeling of the colored image compared to the following situation: the content of the white colorant relative to the white toner particles is less than 20 mass% or exceeds 60 mass%.

[0033] According to the ninth 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 suppresses the peeling of the image during bending compared with the following colorant group for electrostatic charge image development: in the cross-section of the white colorant particles, the area ratio of the white colorant is less than 10% or exceeds 50%, or the number average particle size of the white colorant is less than 0.23μm or exceeds 0.45μm.

[0034] According to the tenth scheme, a colorant group for electrostatic charge image development is provided, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the image during bending, compared with the following situation: when observing the cross-section of the white colorant particles, the area ratio of the white colorant is less than 20% or exceeds 50%, or the number average particle size of the white colorant is less than 0.23μm or exceeds 0.30μm.

[0035] According to the eleventh scheme, a colorant group for electrostatic charge image development is provided, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the image during bending, compared with the following situation: when observing the cross-section of the white colorant particles, the proportion of white colorants with a particle size of less than 100 nm relative to all white colorants exceeds 30% by number.

[0036] According to the twelfth scheme, a colorant group for electrostatic charge image development is provided, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the image during bending, compared with the following situation: when observing the cross-section of the white colorant particles, the proportion of white colorants with a particle size of less than 100 nm relative to all white colorants exceeds 20% by number.

[0037] According to the thirteenth, fourteenth, fifteenth, sixteenth or seventeenth scheme, there is provided an electrostatic charge image developer group, a colorant box group, a processing box, an image forming device, or an image forming method, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the colored image compared to a case where the following electrostatic charge image developing colorant group is applied: the electrostatic charge image developing colorant group 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 having colored colorant particles containing a vinyl resin, a polyester resin and a colored colorant, the mass ratio C of the polyester resin to the vinyl resin in the colored colorant particles being less than 0.7 or greater than 10. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0039] Figure 2 is a schematic structural diagram showing an example of a process cartridge according to the present embodiment;

[0040] Figure 3 This is a schematic diagram showing an example of a screw extruder used in the kneading and pulverizing method. DETAILED DESCRIPTION

[0041] 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.

[0042] In the present embodiment, a numerical range expressed using “to” indicates a range including numerical values ​​described before and after “to” as a minimum value and a maximum value, respectively.

[0043] In the numerical range recorded in stages in the present embodiment, the upper limit or lower limit recorded in a numerical range can also be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical range recorded in the present embodiment, the upper limit or lower limit of this numerical range can also be replaced by the value shown in the embodiment.

[0044] 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.

[0045] 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 sizes, and the relative relationship between the sizes of the components is not limited to this.

[0046] 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.

[0047] In the present embodiment, the term "(meth)acrylic acid" may refer to either "acrylic acid" or "methacrylic acid".

[0048] 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”.

[0049] 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”.

[0050] <Toner set for electrostatic image development>

[0051] The toner set of the present 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.

[0052] 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.

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

[0054] The toner set for image formation on a recording medium such as a colored paper such as black paper or a film such as a beverage label is used to form a colored image on a white image as a base in order to improve the color formation of the colored image.

[0055] Furthermore, the following combination is known: 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 reasons for this are: the white pigment is easily dispersed by using a polyester resin in the white toner, and a balance is achieved by using a vinyl resin that is not prone to charge drop under high temperature and high humidity and a polyester resin that has excellent fixability in the color toner.

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

[0057] However, in the case of a combination in which 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 between the color image and 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, if the components of the white toner particles and the color toner particles are excessively miscible during fixing, the dispersibility of the white colorant of the white image deteriorates, making the light scattering property uneven, thereby reducing the color formation of the color image. In particular, when forming an image on a recording medium with a large surface unevenness such as embossed paper, since the thickness of the white image is uneven, if the dispersibility of the white colorant deteriorates, the color formation 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 set to 0.7 or more and 10 or less.

[0061] By achieving the above mass ratio C, 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.

[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 soluble, and the adhesion between the white image and the color image is fully ensured. In addition, the components of the toner particles are difficult to be excessively soluble, and while suppressing excessive mixing of the components, the deterioration of the dispersibility of the white colorant of the white image is also suppressed. As a result, the mixing of the white colorant and the color colorant is suppressed, and the scattering property of the white image is exerted, and the reduction of the color formation of the color image is suppressed.

[0063] From the above, it is presumed that the toner set of the present embodiment can achieve both suppression of peeling of an image having a color image on a white image and improvement of the color formability of the color image.

[0064] Next, the toner set according to the present embodiment will be described in detail.

[0065] <Resin Amount of White Toner and Color Toner>

[0066] (Mass ratio C)

[0067] 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.

[0068] 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.

[0069] When the mass ratio C exceeds 10, the polyester resin ratio in the colored toner particles is too high, and during fixing, it is excessively mixed with the polyester resin in the white toner particles, resulting in mixing of the white colorant and the colored colorant. In addition, the dispersibility of the white pigment deteriorates and the color formation of the colored image is reduced.

[0070] 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.

[0071] (Relationship between mass ratio C and mass ratio W)

[0072] 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.

[0073] 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.

[0074] When 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, and during fixing, the polyester resins of the white colorant particles and the color colorant particles are moderately mixed, the adhesion between the white image and the color image is sufficiently improved, the reduction in the color formation of the color image is suppressed, and the peeling of the color image is easily suppressed.

[0075] (Measurement of Content of Each Resin Contained in Toner Particles)

[0076] The content of each resin contained in the toner particles (white toner particles and color toner particles) is measured as follows.

[0077] 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.

[0078] 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 device.

[0079] 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.

[0080] Next, the solution component in which the resin component is dissolved is recovered, and the solvent is dried and removed 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.

[0081] Next, 10 mg of the resin component was dissolved in 0.7 mL of a deuterated chloroform solution, and tetramethylsilane (TMS) was added as a reference substance at a concentration of 0.05% by volume. The resulting solution was used as a measurement sample.

[0082] Next, the sample was subjected to 1H-NMR spectrum measurement using a nuclear magnetic resonance apparatus (JNM-AL400 (manufactured by JEOL Ltd.) The measurement conditions were: standard substance: tetramethylsilane (TMS), temperature: 25° C., and cumulative number of times: 128.

[0083] 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.

[0084] 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.

[0085] (Dispersion value P parameter)

[0086] The dispersion value P parameter when the white colorant is measured by the division method on the cross section of the white toner particle is preferably 0.85 or more and 1.00 or less, more preferably 0.90 or more and 1.00 or less, and further preferably 0.92 or more and 1.00 or less.

[0087] When the dispersion value P parameter is within the above range, the dispersibility of the white colorant in the white image after fixing is improved, the light scattering property of the white image is fully utilized, and the color formation of the color image is easily improved.

[0088] The adjustment of the dispersion value P parameter can be exemplified by: in the kneading and pulverizing method described below,

[0089] (1) A two-stage kneading method in which a first kneading step and a second kneading step are performed;

[0090] (2) Methods for controlling the rotation speed of the screw, etc.

[0091] In addition, regarding (1), there can be mentioned a process of kneading 1 / 5 to 1 / 3 of the amount of each resin and the entire amount of the white pigment in the first kneading step, and kneading the remaining amount of each resin in the second kneading step.

[0092] (Cross-sectional characteristics of white toner particles)

[0093] When observing a cross section of the white toner particle, the area ratio of the white colorant is 10% or more and 50% or less, and the number average particle size of the white colorant is 0.23 μm or more and 0.45 μm or less.

[0094] The toner set of the present embodiment has the above-described structure, and has high color formation of an image having a color image on a white image, and suppresses peeling of the image when folding.

[0095] Polyester resin melts at a lower viscosity than vinyl resin, but by including a white colorant in an appropriate amount and size within the above range together with the polyester resin in the white toner particles, the white toner particles become a melt viscosity that is easily soluble in a small amount of polyester resin in the color toner particles at the fixing temperature due to the filling effect of the white colorant. As a result, during fixing, the white toner particles and the color toner particles are soluble, and excessive solubleness is suppressed. Therefore, the white image and the colored image are in a state where the resins are soluble and have high adhesion at the interface, and on the other hand, the components are not excessively mixed and are not easy to crack when bent. As a result, the colorability of the colored image is maintained, and the image peeling during bending is suppressed.

[0096] When the area ratio of the white colorant exceeds 50% or the number average particle size exceeds 0.45 μm, it is difficult to exert a filling effect, and during fixing, the components of the white toner particles and the color toner particles are excessively dissolved or mixed, and the color formation of the color image is reduced.

[0097] When the area ratio of the white colorant is less than 10% or the number average particle size is less than 0.23 μm, the filling effect is excessively exerted, and the components of the white toner particles and the color toner particles are difficult to dissolve during fixing, which easily causes image peeling during bending.

[0098] From the viewpoint of suppressing image peeling and improving the color formation of a colored image, the area ratio of the white colorant is preferably 20% to 50%, and more preferably 30% to 40%.

[0099] From the same viewpoint, the number average particle size of the white colorant is preferably 0.23 μm or more and 0.30 μm or less, and more preferably 0.26 μm or more and 0.30 μm or less.

[0100] The area ratio and number average particle size of the white colorant can be adjusted by using a colorant in which two or more white colorants with different particle sizes are pre-mixed in the kneading and pulverizing method described later, or by adjusting the particle sizes and mixing ratio of the two or more white colorants with different particle sizes.

[0101] (Particle size distribution of white colorant)

[0102] When observing the cross section of white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to the entire white colorants is preferably 30% by number or less, more preferably 20% by number or less, and even more preferably 18% by number or less.

[0103] When the proportion of the white colorant with a particle size of 100 nm or less is within the above range, the viscosity of the white toner becomes a viscosity that is easily compatible with a small amount of polyester resin in the color toner at the fixing temperature due to the filling effect of the white colorant. Therefore, the peeling of the image during bending is suppressed, and the colorability of the image is easily improved.

[0104] The dispersion value P parameter, the area ratio of the white colorant, the number average particle size, and the ratio of the white colorant having a particle size of 100 nm or less are measured as follows.

[0105] The white toner and epoxy resin were mixed and embedded, and the epoxy resin was cured. The obtained cured product was cut using an ultra-thin microtome device (Ultracut UCT manufactured by Leica) to prepare a thin slice sample with a thickness of 250 nm.

[0106] Next, a cross section of the white toner particles of the thin-sheet sample was observed at 10,000 times magnification using a scanning electron microscope STEM (manufactured by Hitachi High-Technologies Corporation: S-4800) to obtain a STEM image.

[0107] Next, the STEM image is analyzed by an image processing analysis system (LUZEX AP manufactured by Nireco Corporation), and the white colorant in the white toner particles is binarized and identified. In the binarization, the contour of the white colorant is extracted based on the color and shape.

[0108] Next, a dividing line is drawn so that the length of the line dividing the cross section of the white toner particle into two parts becomes the maximum, and an analysis area of ​​2 μm in the vertical direction×2 μm in the horizontal direction is acquired so that the center of the dividing line becomes the center.

[0109] Next, the analysis region was divided into four equal parts, each of which had a size of 1 μm in the vertical direction×1 μm in the horizontal direction.

[0110] Next, the dispersion value P parameter is calculated based on the area of ​​the white colorant in each segment using the following formulas (P1) and (P2).

[0111] Then, this operation is performed on 100 white toner particles, and the dispersion value P parameter is measured, and the arithmetic average is calculated.

[0112] In addition, as for the dispersion value P parameter, the closer the value is to 1, the more equal the area of ​​each segment is, indicating that the dispersion of the white colorant is higher, and the closer the value is to 0, the more deviation the area of ​​each segment is, indicating that the dispersion of the white colorant is lower.

[0113] Next, the cross section of the white toner particle and the area of ​​the white colorant on the image are obtained, and the area ratio of the white colorant to the cross section of the white toner particle is obtained.

[0114] This operation is performed on 10 white toner particles, and the arithmetic mean of the area ratio of the white colorant is calculated.

[0115] On the other hand, the equivalent circle diameter of the white colorant on the image is obtained. Specifically, the area of ​​each particle is measured, and the equivalent circle diameter is obtained based on the area value. Then, this operation is performed on 10 white colorant particles to obtain the number-based particle size distribution of the white colorant.

[0116] In the obtained particle size distribution, the particle diameter at which 50% of the particles are accumulated on a number basis is defined as the number average particle diameter.

[0117] In addition, in the obtained particle size distribution, the ratio (number %) of the white colorant having a particle size of 100 nm or less relative to the total white colorant was determined.

[0118] (P1)

[0119] (p2)

[0120] Here, in formulas (P1) to (P2), n represents the number of segments (=4), b i represents the area of ​​white colorant in segment i (μm 2 ).

[0121] <Structure of white toner and color toner>

[0122] Next, constituent components of the toner (white toner and color toner) contained in the toner set according to the present embodiment will be described.

[0123] The toner of this embodiment includes toner particles and may further include an external additive.

[0124] 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.

[0125] In addition, multiple color toners may be used together as the colored toners. For example, four color toners, namely yellow toner, magenta toner, cyan toner, and black toner, may be used together with the white toner to form a toner set. In this case, it is preferred that at least one color toner among the colored toners satisfies the above-mentioned conditions, and it is preferred that all the colored toners used together satisfy the above-mentioned conditions.

[0126] (Toner particles)

[0127] 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.

[0128] The colored toner particles contain a vinyl resin and a polyester resin as a binding resin, and a colored colorant.

[0129] The toner particles (white toner particles and colored toner particles) may contain a release agent and other additives.

[0130] Each component is described below.

[0131] - Adhesive resin -

[0132] The polyester resin will be described.

[0133] As the polyester resin, for example, a known amorphous polyester resin can be cited. The polyester resin can also be used together with a crystalline polyester resin. However, the crystalline polyester resin is preferably used in a range of 2% by mass or more and 40% by mass or less (more preferably 2% by mass or more and 20% by mass or less) relative to the total binder resin.

[0134] The "crystallinity" of a resin means that it has a clear endothermic peak rather than a step-like change in endothermic value in differential scanning calorimetry (DSC). Specifically, it means that the half-value width of the endothermic peak when measured at a heating rate of 10 (°C / min) is within 10°C.

[0135] 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.

[0136] Amorphous polyester resin

[0137] Examples of the non-crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. In addition, commercially available products or synthetic resins may be used as the non-crystalline polyester resin.

[0138] 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 of 1 to 5) alkyl esters thereof. Among these, the polycarboxylic acid is preferably, for example, an aromatic dicarboxylic acid.

[0139] The polycarboxylic acid may also be used together with the dicarboxylic acid to form 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, anhydrides thereof, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof.

[0140] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0141] 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, for example, an aromatic diol or an alicyclic diol, and more preferably an aromatic diol.

[0142] As the polyol, a trivalent or higher polyol having a cross-linked structure or a branched structure may be used together with a diol. Examples of the trivalent or higher polyol include glycerol, trimethylol propane, and pentaerythritol.

[0143] The polyols may be used alone or in combination of two or more.

[0144] 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.

[0145] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, by "extrapolating the glass transition start temperature" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Methods for determining transition temperatures of plastics".

[0146] 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.

[0147] The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less.

[0148] 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.

[0149] In addition, the weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement based on GPC uses a Tosoh GPC HLC-8120GPC as a measuring device, a Tosoh chromatographic column TSKgel SuperHM-M (15 cm), and a THF solvent. The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample based on the measurement results.

[0150] The amorphous polyester resin is obtained by a known production method. Specifically, for example, the amorphous polyester resin is 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 and alcohol generated during condensation.

[0151] 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 mutual solubility, it is preferred to condense the monomers with poor mutual solubility with an acid or alcohol to be polycondensed with the monomers in advance and then polycondense them together with the main component.

[0152] Crystalline polyester resin

[0153] 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.

[0154] Here, in order to easily form a crystal structure, it is more 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.

[0155] 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 2,6-naphthalene dicarboxylic acid, etc.), anhydrides thereof, or lower (e.g., having a carbon number of 1 to 5) alkyl esters thereof.

[0156] The polycarboxylic acid may be used together with the 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.

[0157] As the polycarboxylic acid, a dicarboxylic acid having a sulfonic group or a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.

[0158] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0159] 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 1,14-eicosandiol. Among them, preferred aliphatic diols include 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0160] 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 glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0161] The polyols may be used alone or in combination of two or more.

[0162] Here, the polyol preferably contains an aliphatic diol in an amount of 80 mol % or more, and more preferably 90 mol % or more.

[0163] 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.

[0164] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by the “melting peak temperature” described in the method for determining the melting temperature in JIS K7121-1987 “Methods for determining transition temperatures of plastics”.

[0165] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0166] The crystalline polyester resin can be obtained by a well-known production method, for example, similar to the amorphous polyester.

[0167] Vinyl resin will be described.

[0168] Examples of the vinyl resin include vinyl resins composed of homopolymers of monomers such as 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.), or copolymers formed by combining two or more of these monomers.

[0169] These vinyl resins may be used alone or in combination of two or more.

[0170] As the vinyl resin, a styrene acrylic resin is preferred from the viewpoint of excellent environmental stability of toner charging, excellent charge controllability, excellent color formation of a color image, and excellent suppression of image peeling.

[0171] 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) acryloyloxy 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".

[0172] As the styrene monomer, for example, specifically, styrene, alkyl-substituted styrene (for example, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrene (for example, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), vinylnaphthalene, etc. The styrene monomer may be used alone or in combination of two or more.

[0173] Among them, as the styrene-based monomer, styrene is preferred from the viewpoints of easiness of reaction, easiness of reaction control, and availability.

[0174] As the (meth)acrylic monomer, for example, specifically, (meth)acrylic acid and (meth)acrylic acid esters can be mentioned. As the (meth)acrylic acid esters, for example, (meth)acrylic acid alkyl esters (for example, 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) can be mentioned. Amyl (meth)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)acrylic acid amide, etc. The (meth)acrylic acid monomer may be used alone or in combination of two or more.

[0175] 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.

[0176] The copolymerization ratio of the styrene-based monomer to the (meth)acrylic-based monomer (mass basis, styrene-based monomer / (meth)acrylic-based monomer) is not particularly limited, but is preferably 98 / 2 to 60 / 40.

[0177] The styrene acrylic resin may have 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.

[0178] Examples of the crosslinkable monomer include bifunctional or higher-functional crosslinking agents.

[0179] Examples of the bifunctional crosslinking agent include divinylbenzene, divinylnaphthalene, di(meth)acrylate compounds (e.g., diethylene glycol di(meth)acrylate, methylenebis(meth)acrylic acid amide, decanediol diacrylate, glycerol (meth)acrylate, etc.), polyester di(meth)acrylate, and 2-([1'-methylpropyleneamino]carboxyamino)ethyl methacrylate.

[0180] 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-methacryloyloxy, polyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, and diallyl chlorendic acid.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] Here, the glass transition temperature of the resin is obtained from a DSC curve obtained by differential scanning calorimetry (DSC). More specifically, the glass transition temperature of the resin is obtained according to the "extrapolated glass transition start temperature" described in the method for obtaining the glass transition temperature of JIS K 7121-1987 "Methods for determining transition temperatures of plastics".

[0185] From the viewpoint of storage stability of the toner, the weight average molecular weight of the styrene acrylic resin is preferably 5,000 to 200,000, more preferably 10,000 to 100,000, and particularly preferably 20,000 to 80,000.

[0186] Here, the weight average molecular weight and number average molecular weight of the resin are measured by gel permeation chromatography (GPC). The molecular weight measurement based on GPC uses Tosoh GPC HLC-8120GPC as a measuring device, Tosoh chromatographic column TSKgel SuperHM-M (15cm), and THF solvent. The weight average molecular weight and number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample based on the measurement results.

[0187] The method for preparing the styrene acrylic resin is not particularly limited, and various polymerization methods (e.g., solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.) can be used. In addition, the polymerization reaction can be carried out by known operations (e.g., batch, semi-continuous, continuous, etc.).

[0188] Here, the coexistence of the styrene acrylic resin and the polyester resin can be achieved by mixing the individual resins, or by coexisting as a mixed resin having a styrene acrylic resin segment and a polyester resin segment chemically bonded (so-called styrene acrylic modified polyester resin). Specifically, the mixed resin can be obtained by using a polyester monomer having an unsaturated structure such as fumaric acid or succinic acid or a resin containing the monomer structure as a prepolymer and polymerizing it with a vinyl monomer such as styrene or propylene.

[0189] Furthermore, when a mixed resin (so-called styrene acrylic modified polyester resin) is used, the mass ratio of the polyester segment of the mixed resin to the vinyl resin segment (e.g., styrene acrylic resin segment) is used to measure and calculate the mass ratio C and W of the polyester resin to the vinyl resin. Furthermore, when a mixed 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 mixed resin to the sum of the vinyl resin segment and the vinyl resin of the mixed resin is used to measure and calculate the mass ratio C and W of the polyester resin to the vinyl resin.

[0190] - Colorants -

[0191] As for the colorant, in the case of white toner particles, a white colorant is used, and in the case of colored toner particles, a colored colorant other than the white colorant is used.

[0192] However, in the case of white toner particles, when 15% by mass or more of a white colorant is contained relative to the toner particles, the toner particles are regarded as white toner even if a colored colorant is contained.

[0193] --White colorant--

[0194] Examples of the white colorant include inorganic pigments and organic pigments.

[0195] As white colorants, specifically, inorganic pigments include 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, layered kaolin, aluminosilicate, sericite, bentonite and montmorillonite, and organic pigments include polystyrene resin particles and urea formaldehyde resin particles.

[0196] Among them, from the viewpoint of forming a white image with higher hiding power and better 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.

[0197] In particular, as a white colorant, titanium oxide is preferred from the viewpoint of excellent hiding power. The crystal structure of titanium oxide may be any of anatase type, rutile type, and brookite type.

[0198] As the white colorant, a white colorant subjected to surface treatment as necessary may be used, and a dispersant may be used in combination.

[0199] From the viewpoint of excellent hiding power, the number average particle size of the white colorant measured as a single white colorant (hereinafter also referred to as "the number average particle size Dcc of the single white colorant") is preferably from 150 nm to 900 nm, more preferably from 180 nm to 800 nm, and even more preferably from 200 nm to 700 nm.

[0200] The number average particle diameter Dcc of the white colorant monomer is calculated by the following method: 100 mg of the white colorant is added to 10 ml of a mixture of water and ethanol at a ratio of 1:1 and dispersed with an ultrasonic cleaner, a drop of the dispersion is dropped onto a supporting grid for STEM observation and the dispersion is immediately blown off with a blower to dry, the dried material is observed by STEM using a scanning electron microscope SEM (S-4800 manufactured by Hitachi High-Technologies Corporation) and an image is taken, and the image is input into an image analyzer (LUZEX AP manufactured by Nireco Corporation) for image analysis. Specifically, the area of ​​each particle is measured, and the equivalent circle diameter is calculated based on the area value.

[0201] Specifically, an electron microscope is adjusted so that 10 or more and 50 or less white colorants are reflected in one field of view, and the electron microscope is used to take pictures, and the area of ​​each particle is calculated by image analysis, and the equivalent circle diameter is calculated based on the area value. The average value of 100 equivalent circle diameters in multiple fields of view is defined as the number average particle size Dcc of the white colorant monomer.

[0202] The white coloring agent may be used alone or in combination of two or more.

[0203] 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.

[0204] When the content of the white colorant is within the above range, peeling of the colored image is suppressed and the light scattering property of the white image is improved. In addition, image peeling is suppressed and the reflectance of the white image is high, and the color formation property of the colored image is easily improved.

[0205] --Colored colorants--

[0206] Examples of the colored colorant include carbon black, chrome yellow, Hansa yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, dianisidine orange (vulcan orange), watchung red, permanent red, brilliant carmine 3B, brilliant carmine 6B, Dupont oil red, pyrazolone red, lithotripter red, rhodamine B lake, lake red C, pigment red, Bengal rose red, aniline blue, ultramarine blue, calco oil blue, blue), methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate and other pigments, or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindigo, dioxazine, thiazine, azomethine, indigo, phthalocyanine, nigrosine, polymethine, triphenylmethane, diphenylmethane, thiazole and other dyes.

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

[0208] The content of the colored colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 2% by mass or more and 15% by mass or less, based on the entire colored toner particles.

[0209] - Anti-adhesive agent -

[0210] Examples of the anti-sticking agent include hydrocarbon waxes, natural waxes such as palm wax, rice wax, and candelilla wax, synthetic waxes such as montan wax, or mineral / petroleum waxes, and ester waxes such as fatty acid esters and montanic acid esters. The anti-sticking agent is not limited thereto. The anti-sticking agent for the colored toner particles is preferably an ester wax.

[0211] - Other additives -

[0212] Examples of other additives include known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as internal additives.

[0213] - Characteristics of toner particles, etc. -

[0214] 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 portion (core particle) and a coating layer (shell layer) that covers the core portion.

[0215] Here, the toner particles of the core-shell structure preferably include, 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.

[0216] The volume average particle diameter of the toner particles has an appropriate range for white toner particles and color toner particles, respectively.

[0217] The volume average particle diameter DW of the white toner particles 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.

[0218] The volume average particle diameter DW of the color toner particles 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.

[0219] The volume average particle size of the toner particles was measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the volume average particle size of the electrolyte was measured using ISOTON-II (manufactured by Beckman Coulter).

[0220] When measuring, 0.5 mg to 50 mg of the measuring 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 the electrolyte.

[0221] The electrolyte solution in which the sample was suspended was dispersed with an ultrasonic disperser for 1 minute, and the particle size distribution of particles with a particle size ranging from 2 μm to 60 μm was measured using a Coulter Multisizer II with an aperture of 100 μm. The number of particles sampled was 50,000.

[0222] For the particle size range (channel) divided based on the measured particle size distribution, cumulative distribution is drawn from the smaller diameter side for volume and number, and the particle size that will become 16% of the cumulative value is defined as the volume particle size D16v and the number particle size D16p, and the particle size that will become 50% of the cumulative value is defined as the volume average particle size D50v.

[0223] 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.

[0224] The average circularity of the toner particles is calculated by (equivalent 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.

[0225] First, the toner particles to be measured are sucked and collected to form a flat flow, and the particle image is captured as a static image by instantaneous stroboscopic light. The particle image is analyzed by a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation). The number of samples for obtaining the average circularity is set to 3500.

[0226] 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.

[0227] (External Additives)

[0228] As the external additive, for example, inorganic particles can be mentioned. As the inorganic particles, SiO 2 、TiO 2 、SrTiO 3 、Al 2 O 3 , CuO, ZnO, SnO 2 、CeO 2 , Fe 2 O 3 , MgO, BaO, CaO, K 2 O、Na 2 O, ZrO 2 、CaO·SiO 2 , K 2 O·(TiO 2 )n、Al 2 O 3 ·2SiO 2 、CaCO 3 MgCO 3 ,BaSO 4 MgSO4 wait.

[0229] From the viewpoint of suppressing the peeling of the colored image and improving the light scattering property of the white image and easily improving the coloring property of the colored image, SiO is preferably used as the external additive. 2 .

[0230] The surface of the inorganic particles as an external additive is preferably subjected to hydrophobization. The hydrophobization is carried out, for example, by immersing the inorganic particles in a hydrophobization treatment agent. The hydrophobization treatment agent is not particularly limited, and for example, a silane coupling agent, silicone oil, a titanate coupling agent, an aluminum coupling agent, etc. can be cited. These can be used alone or in combination of two or more.

[0231] 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.

[0232] Examples of the external additives include resin particles (polystyrene, polymethyl methacrylate (PMMA), melamine resin and other resin particles), detergent active agents (for example, metal salts of higher fatty acids represented by zinc stearate, and particles of fluorine-based high molecular weight bodies).

[0233] 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.

[0234] (Method for producing toner)

[0235] Next, a method for producing the toner (white toner and color toner) according to the present embodiment will be described.

[0236] The toner according to the present embodiment is obtained by adding an external additive to toner particles after producing the toner particles.

[0237] The toner particles can be produced by any of dry methods (eg, kneading and pulverization methods) and wet methods (eg, aggregation and coalescence methods, suspension polymerization methods, dissolution and suspension methods, etc.) There are no particular limitations on the method for producing the toner particles, and a known method can be used.

[0238] 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.

[0239] Next, an example of the kneading and pulverizing method and the agglomeration and coalescence method will be described. However, in the description of each production method, the colors are not distinguished.

[0240] (Mixing and pulverizing method)

[0241] The kneading and pulverizing method is a method of obtaining toner particles through the following steps: a kneading step of obtaining a kneaded product by melting and kneading toner particle forming materials (ie, a binder resin, a colorant, etc.); and a pulverizing step of pulverizing the obtained kneaded product.

[0242] -Mixing process-

[0243] 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.

[0244] 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.

[0245] 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 conveying screw portion and two kneading portions will be described with reference to the drawings, but the invention is not limited thereto.

[0246] like Figure 3 As shown, the screw extruder 11 includes a roller 12 having a screw (not shown), an injection port 14 for injecting a colorant particle forming material as a raw material of a colorant 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 mixed product formed by kneading the colorant particle forming material in the roller 12.

[0247] The roller 12 is divided into, starting from the side close to the injection port 14, a conveying 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 conveying screw portion SB for conveying the colorant particle forming material after melt-kneading 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 kneaded product, and a conveying screw portion SC for conveying the formed kneaded product to the discharge port 18.

[0248] A temperature control device (not shown) is provided for each block in the drum 12. That is, the blocks 12A to 12J can be controlled to different temperatures.

[0249] also, Figure 3The 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.

[0250] When the toner particle forming material is supplied from the injection port 14 to the roller 12, the toner particle forming material is conveyed to the kneading section NA by the conveying screw section SA. At this time, since the temperature of the block 12C is set to t1°C, the toner particle forming material is conveyed to the kneading section NA in a state of being heated and molten. Then, since the temperatures of the blocks 12D and 12E are also set to t1°C, the toner particle forming material is melt-kneaded at the temperature of t1°C in the kneading section NA. The binder resin and the release agent become molten in the kneading section NA and are sheared by the screw.

[0251] Next, the toner particle forming material kneaded in the kneading section NA is sent to the kneading section NB by the transport screw section SB.

[0252] Next, in the conveying 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.

[0253] In addition, the method of injecting the aqueous medium into the conveying screw part SB is shown, but the method is not limited thereto, and the aqueous medium may be injected into the kneading part NB, or may be injected into both the conveying screw part SB and the kneading part NB. That is, the position and injection site of the aqueous medium injection are selected as needed.

[0254] 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.

[0255] Finally, the kneaded product formed by melt-kneading in the kneading section NB is conveyed to the discharge port 18 by the conveying screw section SC and discharged from the discharge port 18 .

[0256] As described above, use Figure 3 The kneading process of the screw extruder 11 is shown.

[0257] - Cooling process -

[0258] 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 cooling 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, when quenching at the above-mentioned average cooling rate, the dispersion state immediately after the kneading step is maintained as it is, so it is preferred. In addition, the above-mentioned average cooling rate refers to the temperature of the kneaded product at the end of the kneading step (for example, when using Figure 3 In the case of the screw extruder 11, it is the average value of the speed at which the temperature is reduced from t2°C to 40°C.

[0259] As a cooling method in the cooling process, specifically, for example, a method using a roller that circulates cold water or salt water and an inserted cooling belt can be cited. In addition, when cooling is performed by the above method, the cooling rate is determined according to the speed of the roller, the flow rate of the salt water, the supply amount of the kneaded material, the plate thickness of the kneaded material during rolling, etc. The plate thickness is preferably 1 mm or more and 3 mm or less.

[0260] - Crushing process -

[0261] The kneaded product after cooling in the cooling step is pulverized in a pulverizing step to form particles. In the pulverizing step, for example, a mechanical pulverizer, a jet mill, etc. are used. In addition, hot air, etc. can also be utilized as required to heat-treat the particles to make them spherical.

[0262] - Grading process -

[0263] In order to obtain toner particles with a volume average particle size within the target range, the particles obtained by the pulverization process may be classified by a classification process as needed. In the classification process, a centrifugal classifier, an inertial classifier, etc., which are conventionally used, is used to remove 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).

[0264] Through the above steps, toner particles are obtained.

[0265] (Agglomeration method)

[0266] The aggregation and coalescence method is a method of producing toner particles through the following steps, for example:

[0267] preparing each dispersion (dispersion preparation step);

[0268] 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 are mixed, and the particles and the colorant are aggregated in the obtained dispersion to form first aggregated particles (first aggregated particle forming step);

[0269] 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, and the second resin particles are aggregated on surfaces of the first aggregated particles to form second aggregated particles (second aggregated particle forming step); and

[0270] The second aggregated particle dispersion in which the second aggregated particles are dispersed is heated to fuse / aggregate the second aggregated particles to form toner particles (fusion / aggregation step).

[0271] 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.

[0272] -Each dispersion preparation step-

[0273] 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.

[0274] In addition, in each dispersion liquid preparation step, the first resin particles and the second resin particles are described as “resin particles”.

[0275] Here, the resin particle dispersion is prepared by, for example, dispersing the resin particles in a dispersion medium using a surfactant.

[0276] Examples of the dispersion medium used for the resin particle dispersion include aqueous media.

[0277] 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.

[0278] As surfactants, for example, there can be mentioned: anionic surfactants such as sulfate ester salts, sulfonates, phosphates, soaps, etc.; cationic surfactants such as amine salts, quaternary ammonium salts, etc.; nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, polyols, etc., etc. Among them, anionic surfactants and cationic surfactants can be mentioned in particular. Nonionic surfactants can also be used in combination with anionic surfactants or cationic surfactants.

[0279] The surfactant may be used alone or in combination of two or more.

[0280] In the resin particle dispersion, as a method for dispersing the resin particles in the dispersion medium, for example, a general dispersion method such as a rotary shearing homogenizer, a ball mill with a medium, a sand mill, a DYNO-MILL, etc. can be cited. In addition, depending on the type of the resin particles, for example, a phase inversion emulsification method can be used to disperse the resin particles in the resin particle dispersion.

[0281] In addition, the phase inversion emulsification method refers to the following method: the resin to be dispersed is dissolved in a hydrophobic organic solvent that can dissolve the resin, 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) to make it a discontinuous phase, and the resin is dispersed in the aqueous medium in the form of particles.

[0282] 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.

[0283] In addition, the volume average particle size of the resin particles is measured as follows: using the particle size distribution obtained by measurement using a laser diffraction particle size distribution measuring device (e.g., LA-700 manufactured by Horiba, Ltd.), for the divided particle size range (channel), a cumulative distribution is drawn for the volume from the small particle size side, and the particle size that becomes 50% of the total particles 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.

[0284] 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.

[0285] 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 description of 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 can also be applied to the colorant dispersed in the colorant dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0286] - First Aggregate Particle Formation Step -

[0287] Next, the first resin particle dispersion, the colorant dispersion, and the release agent particle dispersion are mixed.

[0288] 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.

[0289] Specifically, for example, a coagulant is added to a dispersion obtained by mixing a first resin particle dispersion, a colorant dispersion, and a release 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, so that the particles dispersed in the mixed dispersion are agglomerated to form first agglomerated particles.

[0290] In the first aggregated 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 with a rotary shearing homogenizer, the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 or more and 5 or less), and the above-mentioned heating can be performed after adding a dispersion stabilizer as needed.

[0291] 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, and 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.

[0292] 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.

[0293] 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.

[0294] As the chelating agent, a water-soluble chelating agent may also be used. Examples of the chelating agent include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).

[0295] 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 less than 3.0 parts by mass, relative to 100 parts by mass of the first resin particles.

[0296] - Second Aggregate Particle Formation Step -

[0297] Next, after obtaining the first aggregated particle dispersion in which the first aggregated particles are dispersed, the second resin particle dispersion in which the second resin particles are dispersed is added to the first aggregated particle dispersion.

[0298] Furthermore, the second resin particles may be of the same kind as the first resin particles or of a different kind.

[0299] 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 also 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 mixture is heated at a temperature below the glass transition temperature of the second resin particles.

[0300] Then, the progress of aggregation is stopped by adjusting the pH of the dispersion liquid to, for example, a range of about 6.5 or more and 8.5 or less.

[0301] In this way, second aggregated particles are obtained in which the second resin particles are aggregated so as to adhere to the surfaces of the first aggregated particles.

[0302] - Fusion / agglomeration process -

[0303] Next, the second aggregated particle dispersion containing the second aggregated particles is heated to, for example, 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 / agglomerate the second aggregated particles to form toner particles.

[0304] Through the above steps, toner particles are obtained.

[0305] 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 multiple times.

[0306] Here, after the fusion / aggregation 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.

[0307] From the viewpoint of chargeability, the washing process preferably fully implements replacement washing using ion exchange water. In addition, the solid-liquid separation process is not particularly limited, but from the viewpoint of productivity, it is preferably implemented by suction filtration, pressure filtration, etc. In addition, the method of the drying process is not particularly limited, but from the viewpoint of productivity, it is preferably implemented by freeze drying, air flow drying, fluidized drying, vibration type fluidized drying, etc.

[0308] Furthermore, in the method for producing a toner according to the embodiment of the present application, for example, an external additive may be added and mixed with the toner particles obtained by the method for producing toner particles described above.

[0309] The mixing is preferably performed by, for example, a V-type mixer, a Henschel mixer, a Lödige mixer, etc. If necessary, coarse particles of the toner may be removed using a vibration sieving machine, a wind sieving machine, etc.

[0310] <Electrostatic image developer set>

[0311] 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.

[0312] 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.

[0313] The carrier is not particularly limited, and known carriers may be cited. 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 / blended in a matrix resin; and a resin impregnated carrier in which a porous magnetic powder is impregnated with a resin.

[0314] 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 a core material and the core material is coated with a coating resin.

[0315] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0316] As the coating resin and the matrix resin, for example, there can be mentioned: 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; ordinary silicone resin composed of organic siloxane bonds or its modified products; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; amino resins such as urea formaldehyde resin; epoxy resin, etc.

[0317] The coating resin and the matrix resin preferably contain a (meth)acrylic resin, more preferably contain 50 mass % or more of an alicyclic (meth)acrylic resin based on the total mass of the resin, and particularly preferably contain 80 mass % or more of a (meth)acrylic resin based on the total mass of the resin.

[0318] Furthermore, other additives such as conductive particles may be contained in the coating resin and the matrix resin.

[0319] 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.

[0320] Here, in order to coat the surface of the core material with coating resin, a coating layer formed by dissolving the coating resin and various additives added as required in a suitable solvent can be enumerated to coat with a solution etc. There is no particular restriction on the solvent, and the coating resin used, coating adaptability etc. can be selected in consideration.

[0321] 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 core material is suspended in the state of being suspended by flowing air and the coating layer forming solution is sprayed on it; 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, etc.

[0322] 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.

[0323] <Image forming apparatus, image forming method>

[0324] An image forming apparatus and an image forming method according to the present embodiment will be described.

[0325] The image forming device of the present embodiment comprises: a first image forming unit, which comprises a first developing unit that accommodates a white electrostatic charge image developer contained in the developer group of the present embodiment and forms a white image; a second image forming unit, which comprises a second developing unit that accommodates a colored electrostatic charge image developer contained in the developer group of the present embodiment and forms a colored image using a colored toner; a transfer unit that transfers the white image and the colored image to the surface of a recording medium; and a fixing unit that fixes the white image and the colored image transferred to the surface of the recording medium.

[0326] The image forming device of this embodiment can also be a type that includes each image forming unit as a first or second image forming unit, and each image forming unit respectively 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 into a colorant image using an electrostatic charge image developer.

[0327] In addition, the image forming device of the present embodiment may be of the following type: it 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 first or second developing unit as a first or second image forming unit for developing the electrostatic charge image formed on the surface of the image retaining body into a colorant image using an electrostatic charge image developer.

[0328] 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 comprises: a first image forming step of forming a white image using the white colorant in the electrostatic charge image developing colorant group of the present embodiment; a second image forming step of forming a colored image using the colored colorants in the electrostatic charge image developing colorant group of the present embodiment; a transfer step of transferring the white image and the colored image to a recording medium; and a fixing step of fixing the white image and the colored image to the recording medium.

[0329] The structure of the image forming device of the present embodiment can be applied to the following well-known image forming devices: a device of a direct transfer method that directly transfers the colorant image (a white image or a colored image in the present embodiment) formed on the surface of the image retaining body to a recording medium; a device of an intermediate transfer method that transfers the colorant image formed on the surface of the image retaining body to the surface of an intermediate transfer body for the first time, and transfers the colorant image transferred to the surface of the intermediate transfer body to the surface of a recording medium for a second time; a device having a cleaning unit that cleans the surface of the image retaining body after the transfer of the colorant image and before charging; a device having a de-staticizing unit that de-staticizes the surface of the image retaining body by irradiating de-staticizing light to the surface of the image retaining body after the transfer of the colorant image and before charging, etc.

[0330] In the case of an intermediate transfer type device, the transfer unit, for example, has a structure comprising an intermediate transfer body on the surface of which a colorant image is transferred, 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 to the surface of a recording medium for the second time.

[0331] In addition, in the image forming apparatus of the present embodiment, for example, the portion including the developing unit may also be a box structure (processing box) that is detachable from the image forming apparatus. As the processing box, for example, a processing box having a developing unit that accommodates the electrostatic image developer group of the present embodiment is preferably used.

[0332] The image forming device of this embodiment can also be an image forming device as follows: the white colorant contained in the colorant group of this embodiment is stored in the developing unit, and at least one selected from the yellow colorant, magenta colorant, cyan colorant, and black colorant as colored colorants is stored in the developing unit.

[0333] 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 applied. For example, resin films or sheets, paper, etc. can be cited. As the uses of the resin films or sheets, packaging, labels, packaging materials, promotional media, OHP sheets, etc. can be cited.

[0334] As the resin film or sheet, there can be cited 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 of 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 of a single layer or multiple layers. The resin film or sheet may also be a film having a surface coating layer for assisting the fixing of a toner, a film or sheet subjected to a corona treatment, an ozone treatment, a plasma treatment, a flame treatment, a glow discharge treatment, etc.

[0335] Examples of the lamination order of the recording medium, the color image, and the white image (cover layer) include the following (a), (b), and (c).

[0336] Lamination order (a): from the side closest to the viewer, transmissive recording medium / colored image / white image (covering layer).

[0337] Lamination order (b): from the side closest to the viewer, colored image / transmissive recording medium / white image (covering layer).

[0338] Lamination order (c): from the side closest to the viewer, color image / white image (covering layer) / recording medium (regardless of whether it has transmittance).

[0339] 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 are described, and the description of other parts is omitted.

[0340] 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-column system and an intermediate transfer system.

[0341] Figure 1 The image forming apparatus shown in the figure has 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) colors based on color-decomposed image data. These image forming units (hereinafter, sometimes simply referred to as "units") 10Y, 10M, 10C, 10K, 10W are arranged in parallel with each other at a predetermined distance 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.

[0342] 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 a counter roller 24 that are in contact with the inner surface of the intermediate transfer belt 20, and travels in the direction from the first unit 10Y toward the fifth unit 10W. An intermediate transfer body cleaning device 21 is provided on the image holding surface side of the intermediate transfer belt 20, which is opposite to the driving roller 22.

[0343] Yellow, magenta, cyan, black and white toners stored 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 respective units 10Y, 10M, 10C, 10K and 10W.

[0344] The first to fifth units 10Y, 10M, 10C, 10K, and 10W have similar structures, operations, and functions, and therefore 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.

[0345] The first unit 10Y has a photoreceptor 1Y that functions as an image holder. Around the photoreceptor 1Y, there are arranged in order: a charging roller (an example of a charging unit) 2Y that charges the surface of the photoreceptor 1Y to a preset potential, an exposure device (an example of an electrostatic image forming unit) 3Y that forms an electrostatic image by exposing the charged surface to laser light based on a color-separated image signal, a developing device (an example of a developing unit) 4Y that supplies toner to the electrostatic image and develops the electrostatic 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.

[0346] 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. The primary transfer rollers 5Y, 5M, 5C, 5K, and 5W of each unit are connected to bias power supplies (not shown) for applying primary transfer bias. Each bias power supply is controlled by a control unit (not shown) to change the value of the transfer bias applied to each primary transfer roller.

[0347] Next, the operation of forming a yellow image in the first unit 10Y will be described.

[0348] First, before operation, the surface of the photoreceptor 1Y is charged to a potential of -600 V to -800 V by the charging roller 2Y.

[0349] The photoreceptor 1Y is conductive (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 has the following properties: it is usually high in resistance (resistance of a general resin), but when irradiated with laser light, the specific resistance of the portion irradiated with the laser light changes. Therefore, according to the yellow image data 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.

[0350] An electrostatic charge image refers to 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: due to the laser light from the exposure device 3Y, the resistivity of the irradiated portion of the photosensitive layer is reduced, so that the charged charge flows on the surface of the photoreceptor 1Y, while on the other hand, the charge of the portion not irradiated by the laser light remains.

[0351] The electrostatic charge image formed on the photoreceptor 1Y rotates to a preset development position as the photoreceptor 1Y travels. Then, 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.

[0352] In the developing device 4Y, for example, an electrostatic charge image developer containing at least a yellow colorant and a carrier is stored. The yellow colorant is stirred inside the developing device 4Y, thereby being triboelectrically charged, and has a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y and is retained on the developer roller (an example of a developer retainer). Then, the surface of the photoreceptor 1Y passes through the developing device 4Y, whereby the yellow colorant is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y after the charge is removed, and the latent image is developed by the yellow colorant. The photoreceptor 1Y formed with the yellow colorant image continues to move at a preset speed, and the toner image developed on the photoreceptor 1Y is conveyed to a preset primary transfer position.

[0353] When the yellow toner image on the photoreceptor 1Y is conveyed 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 to, for example, +10 μA by a control section (not shown) in the first unit 10Y.

[0354] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0355] 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.

[0356] Thus, the intermediate transfer belt 20 to which the yellow toner image is transferred in 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 superimposed and multi-transferred.

[0357] The intermediate transfer belt 20 to which the five-color toner images have been multi-transferred through the first to fifth units arrives at the secondary transfer section, which is composed of the intermediate transfer belt 20, the counter roller 24 in contact with the inner surface of the intermediate transfer belt, and the secondary transfer roller (an example of the secondary transfer unit) 26 arranged on the image holding surface side of the intermediate transfer belt 20. On the other hand, the recording paper (an example of the recording medium) P is supplied to the gap between the secondary transfer roller 26 and the intermediate transfer belt 20 at a preset timing via a supply mechanism, and a secondary transfer bias is applied to the counter roller 24. At this time, the applied transfer bias has the same polarity (-) as the polarity (-) of the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and 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 portion, and is voltage-controlled.

[0358] 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 to the recording paper P, thereby forming a fixed image.

[0359] 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 sheets, in addition to the recording paper P.

[0360] In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is preferably smooth, and 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.

[0361] 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.

[0362] <Process Cartridge / Toner Cartridge Set>

[0363] The process cartridge according to this embodiment will be described.

[0364] The processing box of this embodiment is a processing box that has a first developing unit and a second developing unit and is installed and removed from an image forming device. The first developing unit accommodates the white electrostatic charge image developer in the electrostatic charge image developer group of this embodiment, and the second developing unit accommodates the colored electrostatic charge image developer in the electrostatic charge image developer group of this embodiment.

[0365] The process cartridge of this embodiment is not limited to the above structure, but may be a structure including a developing device and, if necessary, at least one of other units selected from an image holder, a charging unit, an electrostatic charge image forming unit, and a transfer unit.

[0366] 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 drawings will be described, and the description of other parts will be omitted.

[0367] Figure 2 It is a schematic structural diagram showing a process cartridge according to the present embodiment.

[0368] 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, by which a photosensitive body 107 (an example of an image retaining body), a charging roller 108 (an example of a charging unit) provided 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) are integrally combined and held to form a box.

[0369] 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).

[0370] Next, the toner cartridge according to the present embodiment will be described.

[0371] The toner cartridge set of the present embodiment is a toner cartridge set including a white toner cartridge and a color toner cartridge. The white toner cartridge stores the white toner contained in the toner cartridge set of the present embodiment and is attached to and detached from the image forming apparatus, and the color toner cartridge stores the color toner contained in the toner cartridge set of the present embodiment and is attached to and detached from the image forming apparatus. The toner cartridge set stores supplementary toner for supplying to a developing unit provided in the image forming apparatus.

[0372] also, Figure 2The image forming apparatus shown is an image forming apparatus having a structure in which toner cartridges 8Y, 8M, 8C, 8K, and 8W are detachably mounted, and the developing devices 4Y, 4M, 4C, 4K, and 4W are connected to toner cartridges corresponding to the respective developing devices (colors) through toner supply pipes not shown. In addition, when the toner stored in the toner cartridge becomes low, the toner cartridge is replaced.

[0373] [Example]

[0374] 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 by mass unless otherwise specified.

[0375] <Preparation of various dispersions>

[0376] (Synthesis of Amorphous Polyester Resin (A))

[0377] Terephthalic acid: 68 parts

[0378] Fumaric acid: 32 parts

[0379] Ethylene glycol: 42 parts

[0380] 1,5-Pentanediol: 47 parts

[0381] The above materials were added to a flask equipped with a stirring device, a nitrogen introduction tube, a temperature sensor and a distillation tower. The temperature was raised to 220°C over 1 hour under a nitrogen flow, and 1 part of tetraethoxytitanium was added to 100 parts of the above materials in total. The temperature was raised to 240°C over 0.5 hours while the generated water was distilled off. After the dehydration condensation reaction was continued at 240°C for 1 hour, the reactant was cooled. Thus, an amorphous polyester resin (A) with a weight average molecular weight of 97,000 and a glass transition temperature of 60°C was obtained.

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

[0383] After adding 40 parts of ethyl acetate and 25 parts of 2-butanol to a container equipped with a temperature control unit and a nitrogen replacement unit to prepare a mixed solvent, 100 parts of amorphous polyester resin (A) are slowly added to dissolve it, and a 10% ammonia solution (equivalent to 3 times the amount in molar ratio relative to the acid value of the resin) is added thereto, and stirred for 30 minutes. Next, the container is replaced with dry nitrogen, the temperature is maintained at 40°C, and 400 parts of ion exchange water are dripped while stirring the mixed liquid to emulsify. After the dripping is completed, the emulsion is returned to 25°C to obtain a resin particle dispersion in which resin particles with a volume average particle size of 195nm are dispersed. Ion exchange water is added to the resin particle dispersion, and the solid content is adjusted to 20% to obtain an amorphous polyester resin particle dispersion (A1).

[0384] (Preparation of Crystalline Polyester Resin Particle Dispersion Liquid (B1))

[0385] 1,10-Decanedicarboxylic acid: 260 parts

[0386] 1,6-Hexanediol: 167 parts

[0387] Dibutyltin oxide (catalyst): 0.3 parts

[0388] The above materials were added to a three-necked flask after heating and drying, 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 slowly raised to 230°C under reduced pressure, stirred for 2 hours, and air-cooled when it became viscous to stop the reaction. Thus, 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 Co., Ltd., 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 Co.), and then dispersed for 1 hour using a pressure discharge type Gaulin homogenizer 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).

[0389] (Preparation of Styrene Acrylic Resin Particle Dispersion Liquid (S1))

[0390] Styrene: 375 parts

[0391] n-Butyl acrylate: 25 parts

[0392] Acrylic acid: 2 parts

[0393] · Dodecanethiol: 24 parts

[0394] Carbon tetrabromide: 4 parts

[0395] In a flask, the mixture in which the above materials are mixed and dissolved is dispersed and emulsified in a surfactant solution, which is prepared by dissolving 6 parts of a nonionic surfactant (Nonipole 400 manufactured by Sanyo Chemical Industries) and 10 parts of anionic surfactant (Tayca Power, manufactured by Tayca (Co., Ltd.), solid content 12%, sodium dodecylbenzenesulfonate) in 550 parts of ion exchange water. Next, an aqueous solution prepared by dissolving 4 parts of ammonium persulfate in 50 parts of ion exchange water is added while stirring in the flask for 20 minutes. Next, after nitrogen substitution, the contents are heated to 70°C in an oil bath while stirring in the flask, maintained at 70°C for 5 hours, and emulsion polymerization is continued. Thus, 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 20%, to obtain a styrene acrylic resin particle dispersion (S1).

[0396] (Preparation of Colorant Dispersion Liquid (Cy1))

[0397] CI Pigment Blue 15:3 (produced by Dainichi Seika Industries): 70 parts

[0398] Anionic surfactant (Neogen RK manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part

[0399] Ion exchange water: 200 parts

[0400] 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.

[0401] (Preparation of Anti-sticking Agent Particle Dispersion Liquid (W1))

[0402] Ester wax (produced by NOF Corporation, WEP-8, melting point 79°C): 100 parts

[0403] Anionic surfactant: 1 part (Tayca Power, manufactured by Tayca Corporation, solid content 12%, sodium dodecylbenzenesulfonate)

[0404] Ion exchange water: 350 parts

[0405] The above materials were mixed, heated to 100°C, dispersed using a homogenizer (ULTRA-TURRAX T50 manufactured by IKA), and then dispersed using a pressure discharge type Gaulin homogenizer to obtain a release agent particle dispersion in which release agent particles having a volume average particle size of 1000 nm were dispersed. Ion exchange water was added to the release agent particle dispersion to adjust the solid content to 20% to prepare a release agent particle dispersion (W1).

[0406] (Preparation of Styrene Acrylic Modified Polyester Resin Particle Dispersion (SPE1))

[0407] The interior of a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 5,670 parts of polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, 585 parts of polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl)propane, 2,450 parts of terephthalic acid, and 44 parts of di(2-ethylhexanoate)tin(II) were placed. The temperature was raised to 235°C under a nitrogen atmosphere while stirring. After maintaining the temperature for 5 hours, the pressure in the flask was further reduced and maintained at 8.0 kPa for 1 hour. After returning to atmospheric pressure, the flask was cooled to 190°C, 42 parts of fumaric acid and 207 parts of trimellitic acid were added, and the temperature was maintained at 190°C for 2 hours. The temperature was then raised to 210°C over 2 hours. The pressure in the flask was further reduced and maintained at 8.0 kPa for 4 hours to obtain a non-crystalline polyester resin A (polyester segment).

[0408] Next, 800 parts of amorphous polyester resin A were added to a four-necked flask equipped with a cooling tube, a stirring device and a thermocouple, and stirred at a stirring speed of 200 rpm under a nitrogen atmosphere. Then, as addition polymerizable monomers, 100 parts of styrene, 82 parts of ethyl acrylate, 16 parts of acrylic acid, 2 parts of 1,10-decanediol diacrylate and 1,000 parts of toluene were added, and mixed for further 30 minutes.

[0409] Furthermore, 6 parts of polyoxyethylene alkyl ether (nonionic surfactant, trade name: Emulgen 430, manufactured by Kao Corporation), 40 parts of 15% sodium dodecylbenzenesulfonate aqueous solution (anionic surfactant, trade name: Neopelex G-15, manufactured by Kao Corporation) and 233 parts of 5% potassium hydroxide were added, and the mixture was heated to 95°C for melting while stirring, and mixed at 95°C for 2 hours to obtain a resin mixture solution.

[0410] Next, while stirring the resin mixture solution, 1,145 parts of deionized water was dropped at a rate of 6 parts / minute to obtain an emulsion. Next, the obtained emulsion was cooled to 25°C, passed through a 200-mesh metal screen, and deionized water was added to adjust the solid content to 20%, thereby obtaining a styrene-acrylic acid modified polyester resin particle dispersion (SPE1).

[0411] Furthermore, the "mass ratio of the styrene-acrylic resin segment to the polyester resin segment (styrene-acrylic resin segment / polyester resin segment)" of the synthesized styrene-acrylic modified polyester resin was 20 / 80.

[0412] (Preparation of styrene acrylic modified polyester resin particle dispersion (SPE101))

[0413] A styrene acrylic acid-modified polyester resin particle dispersion (SPE101) was obtained in the same manner as in the styrene acrylic acid-modified polyester resin particle dispersion (SPE1) except that the solid content was adjusted to 30%.

[0414] <Production of white colorant>

[0415] (Preparation of Titanium Oxide Particles (T1))

[0416] 0.15 mol of glycerol was added to 100 mL of 1 mol / L titanium tetrachloride aqueous solution, heated at 90°C for 4 hours, and then filtered. The obtained white powder was dispersed in 100 mL of ion exchange water, 0.4 mol of hydrochloric acid was added, and heated at 90°C for 3 hours again. After adjusting the pH to 7 with sodium hydroxide, the mixture was filtered and washed with water, and dried at 105°C for 12 hours to obtain hydrous titanium dioxide particles (1). 0.25 parts of Al 2 O 3 , 0.1 parts aluminum sulfate, 1.2 parts K 2 O, 0.01 parts P 2 O 5 , and fired at 950°C for 2 hours to obtain titanium oxide particles (T1) with a number average particle size Dcc of 500 nm.

[0417] (Preparation of Titanium Oxide Particles (T2))

[0418] In addition to P 2 O 5 Titanium oxide particles (T2) having a number average particle diameter Dcc of 220 nm were obtained in the same manner as in the titanium oxide particles (T1), except that the amount of was changed to 0.05 parts and the firing temperature was changed to 930°C.

[0419] (Preparation of Titanium Oxide Particles (T3))

[0420] In addition to P 2 O 5 The amount of K 2 Titanium oxide particles (T3) having a number average particle diameter Dcc of 155 nm were obtained in the same manner as in the titanium oxide particles (T1) except that the amount of O was changed to 0.5 parts and the firing temperature was changed to 920°C.

[0421] (Preparation of Titanium Oxide Particles (T4))

[0422] In addition to P 2 O 5 The amount of K 2 Titanium oxide particles (T4) having a number average particle diameter Dcc of 570 nm were obtained in the same manner as the titanium oxide particles (T1) except that the amount of O was 1.2 parts, the firing temperature was 970° C., and the firing time was 3 hours.

[0423] (Production of white colorant (MT1))

[0424] 30 parts of titanium oxide particles (T1) and 70 parts of titanium oxide particles (T2) were mixed with 200 parts of ion exchange water adjusted to pH 4 using a 0.1% hydrogen chloride solution, and the mixture was dispersed by ball milling overnight. After that, the mixture was allowed to stand, the supernatant was removed, and the mixture was dried for 12 hours using a freeze vacuum dryer, and then pulverized using a jet mill and sieved to remove coarse powder. Thus, a white colorant (MT1) with a number average particle size Dcc of 280 nm was obtained.

[0425] (Production of white coloring agents (MT2) to (MT16))

[0426] After mixing the titanium oxide particles (T1) in the amount A (parts) shown in Table 3, the titanium oxide particles (T2) in the amount B (parts) shown in Table 3, and the titanium oxide particles (T3) in the amount C (parts) shown in Table 3 with 200 parts of ion exchange water adjusted to pH 4 with a 0.1-specified hydrogen chloride solution, the mixture was dispersed by ball milling overnight. Thereafter, the mixture was allowed to stand, the supernatant was removed, and the mixture was dried for 12 hours using a freeze vacuum dryer, and then pulverized using a jet mill and sieved to remove coarse powder. Thus, white colorants (MT2) to (MT16) having a number average particle size Dcc shown in Table 3 were obtained.

[0427] (Production of white colorant (MT17))

[0428] 100 parts of titanium oxide particles (T4) were mixed with 200 parts of ion exchange water adjusted to pH 4 using a 0.1% hydrogen chloride solution, and the mixture was dispersed by ball milling overnight. After that, the mixture was allowed to stand, the supernatant was removed, and the mixture was dried in a freeze vacuum dryer for 12 hours, and then pulverized in a jet mill and sieved to remove coarse powder. Thus, a white colorant (MT17) with a number average particle size Dcc of 525 nm was obtained.

[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): 10 parts

[0435] Styrene acrylic resin particle dispersion (S1): 60 parts

[0436] Crystalline polyester resin particle dispersion (B1): 10 parts

[0437] Amorphous polyester resin particle dispersion (A1): 310 parts

[0438] The above materials were placed in a round stainless steel flask, 0.1N (0.1 mol / L) nitric acid was added, and the pH was adjusted to 3.5, and then an aqueous solution of magnesium chloride prepared 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 reached 4.5 μm.

[0439] - Second Aggregate Particle Formation Step -

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

[0441] - Fusion / agglomeration process -

[0442] Next, the temperature was raised to 85°C at a rate of 0.5°C / min while stirring was continued, and after being kept at 85°C for 3 hours, the mixture was cooled to 30°C at a rate of 15°C / min (first cooling). Next, the mixture was heated to 85°C at a rate of 0.2°C / min (re-heating), and after being kept for 30 minutes, the mixture was cooled to 30°C at a rate of 0.5°C / min (second cooling).

[0443] Next, the solid content was separated by filtration, 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 10,000 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 toner (CT2))

[0447] Cyan toner (CT2) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 220 parts and the amorphous polyester resin particle dispersion (A1) was changed to 150 parts.

[0448] (Production of cyan toner (CT3))

[0449] Cyan toner (CT3) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 16.4 parts and the amorphous polyester resin particle dispersion (A1) was changed to 353.6 parts.

[0450] (Production of cyan toner (CT4))

[0451] Cyan toner (CT4) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 113.3 parts and the amorphous polyester resin particle dispersion (A1) was changed to 256.7 parts.

[0452] (Production of cyan toner (CT5))

[0453] Cyan toner (CT5) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 37.1 parts and the amorphous polyester resin particle dispersion (A1) was changed to 332.9 parts.

[0454] (Production of cyan toner (CT6))

[0455] Cyan toner (CT6) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 38.1 parts and the amorphous polyester resin particle dispersion (A1) was changed to 331.9 parts.

[0456] (Production of cyan toner (CT7))

[0457] Cyan toner (CT7) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 32.2 parts and the amorphous polyester resin particle dispersion (A1) was changed to 337.8 parts.

[0458] (Production of cyan toner (CT8))

[0459] Cyan toner (CT8) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 180 parts and the amorphous polyester resin particle dispersion (A1) was changed to 190 parts.

[0460] (Production of cyan toner (CT9))

[0461] A cyan toner (CT9) was obtained in the same manner as the cyan toner (CT1), except that 380 parts of a styrene acrylic modified polyester resin particle dispersion (SPE1) was used instead of the styrene acrylic resin particle dispersion (S1) and the amorphous polyester resin particle dispersion (A1) in the first aggregated particle forming step, and the same amount of a styrene acrylic modified polyester resin particle dispersion (SPE1) was used instead of the styrene acrylic resin particle dispersion (S1) in the second aggregated particle forming step.

[0462] (Production of cyan toner (CT10))

[0463] Cyan toner (CT10) was obtained in the same manner as in the cyan toner (CT1) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 343.6 parts and the amorphous polyester resin particle dispersion (A1) was changed to 26.4 parts.

[0464] (Production of cyan toner (CT11))

[0465] Cyan toner (CT11) was obtained in the same manner as in the cyan toner (CT1) except that the styrene acrylic resin particle dispersion (S1) was changed to 5 parts and the amorphous polyester resin particle dispersion (A1) was changed to 365 parts in the first aggregated particle forming step.

[0466] (Production of cyan toner (CT101))

[0467] A cyan toner (CT101) was obtained in the same manner as the cyan toner (CT1), except that in the first aggregated particle formation step, the styrene acrylic resin particle dispersion (S1) was changed to 40 parts, the amorphous polyester resin particle dispersion (A1) was changed to 230 parts, and the heating rate when heating to 85°C in the fusion and coalescence step was changed to 0.05°C / min.

[0468] (Production of cyan toner (CT102))

[0469] Cyan toner (CT102) was obtained in the same manner as in the cyan toner (CT101) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 160 parts and the amorphous polyester resin particle dispersion (A1) was changed to 110 parts.

[0470] (Production of cyan toner (CT103))

[0471] Cyan toner (CT103) was obtained in the same manner as in the cyan toner (CT101) except that in the first aggregated particle forming step, the styrene acrylic resin particle dispersion (S1) was changed to 80 parts and the amorphous polyester resin particle dispersion (A1) was changed to 190 parts.

[0472] (Production of cyan toner (CT104))

[0473] Cyan toner (CT104) was obtained in the same manner as in the cyan toner (CT101) except that the styrene acrylic resin particle dispersion (S1) was changed to 25 parts and the amorphous polyester resin particle dispersion (A1) was changed to 250 parts in the first aggregated particle forming step.

[0474] (Production of cyan toner (CT105))

[0475] Cyan toner (CT105) was obtained in the same manner as in the cyan toner (CT101) except that the styrene acrylic resin particle dispersion (S1) was changed to 5 parts and the amorphous polyester resin particle dispersion (A1) was changed to 265 parts in the first aggregated particle forming step.

[0476] (Production of cyan toner (CT106))

[0477] Cyan toner (CT106) was obtained in the same manner as in the cyan toner (CT101) except that the styrene acrylic resin particle dispersion (S1) was changed to 17 parts and the amorphous polyester resin particle dispersion (A1) was changed to 100 parts in the first aggregated particle forming step.

[0478] (Production of cyan toner (CT107))

[0479] Cyan toner (CT107) was obtained in the same manner as in the cyan toner (CT101) except that the styrene acrylic resin particle dispersion (S1) was changed to 0 parts and the amorphous polyester resin particle dispersion (A1) was changed to 270 parts in the first aggregated particle forming step.

[0480] (Production of cyan toner (CT108))

[0481] A cyan toner (CT108) was obtained in the same manner as the cyan toner (CT101) except that 270 parts of the styrene acrylic modified polyester resin particle dispersion (SPE1) was used instead of the styrene acrylic resin particle dispersion (S1) and the amorphous polyester resin particle dispersion (A1) in the first aggregated particle forming step.

[0482] (Production of cyan toner (CT109))

[0483] A cyan toner (CT109) was obtained in the same manner as in the cyan toner (CT101), except that the styrene acrylic resin particle dispersion (S1) was set to 0 parts and the amorphous polyester resin particle dispersion (A1) was set to 270 parts in the first aggregated particle forming step, and the amorphous polyester resin particle dispersion (A1) was used instead of the styrene acrylic resin particle dispersion (S1) in the second aggregated particle forming step.

[0484] <Production of white toner>

[0485] (Preparation of White Toner (WT1))

[0486] - Preparation of toner particle forming materials -

[0487] As toner particle forming materials, the following materials were prepared.

[0488] Polyester resin (polyester resin synthesized with bisphenol A propylene oxide 2 mole adduct / ethylene oxide 2 mole adduct, terephthalic acid, trimellitic acid as main components and using tin catalyst): 100 parts

[0489] Styrene acrylic resin (resin prepared by polymerizing styrene and butyl acrylate under cumene reflux): 15 parts

[0490] White colorant (titanium oxide particles (manufactured by Ishihara Sangyo Co., Ltd., product name: CR-60-2)): 80 parts

[0491] Anti-adhesive agent (polypropylene; Mitsui Chemicals, Inc., Mitsui HI-WAX NP055): 5 parts

[0492] - First mixing process -

[0493] A quarter of the polyester resin, a quarter of the styrene acrylic resin, and the entire amount of the white colorant in the toner particle forming material were mixed using a Henschel mixer, and then Figure 3 The twin-screw extruder (ie, continuous kneading machine) shown above carried out kneading under the following conditions: The rotation speed of the screw was set to 600 rpm.

[0494] Feeding section (blocks 12A and 12B) set temperature: 20°C

[0495] Kneading section 1 mixing setting temperature (blocks 12C to 12E): 80°C

[0496] Kneading section 2 kneading setting temperature (blocks 12F to 12J): 90°C

[0497] · Amount of water-based medium (distilled water) added (relative to 100 parts of raw material supply): 1.5 parts

[0498] In addition, 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 100°C.

[0499] The obtained kneaded product was quenched with a roller having salt water at -5°C passed through it and a plate-layer intercalated cooling belt cooled with cold water at 2°C, and after cooling, it was crushed with a hammer mill to obtain a colorant concentrated resin composition. The quenching speed was confirmed by changing the speed of the cooling belt, but the average temperature drop rate was 10°C / sec.

[0500] - Second mixing process -

[0501] The colorant concentrated resin composition obtained in the first kneading step and the remaining toner particle forming material not used in the first kneading step are mixed with a Henschel mixer, and then Figure 3 The kneading was carried out in the twin-screw extruder (ie, continuous kneading machine) shown below under the following conditions: The screw rotation speed was set to 600 rpm.

[0502] Feeding section (blocks 12A and 12B) set temperature: 20°C

[0503] Kneading section 1 mixing setting temperature (blocks 12C to 12E): 80°C

[0504] Kneading section 2 kneading setting temperature (blocks 12F to 12J): 90°C

[0505] · Amount of water-based medium (distilled water) added (relative to 100 parts of raw material supply): 1.5 parts

[0506] In addition, 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 100°C.

[0507] The obtained kneaded product was quenched with a roller through which salt water at -5°C was passed and a plate-layer inserted cooling belt cooled with cold water at 2°C, and after cooling, it was crushed with a hammer mill. The quenching speed was confirmed by changing the speed of the cooling belt, but the average temperature drop rate was 10°C / sec.

[0508] The kneaded product obtained in the second kneading step was then pulverized by a pulverizer (AFG400) equipped with a 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 (W1) having a volume average particle size of 6.0 μm.

[0509] - Addition of external additives -

[0510] 1.5 parts of hydrophobic silica (RY50 manufactured by Nippon Aerosil Co., Ltd.) and 1.2 parts of spherical silica treated with hexamethyldisilazane having an average particle size of 130 nm were added to the obtained white colorant particles (W1), mixed (external addition) for 10 minutes using a Henschel mixer, and then sieved at 45 μm using a wind sifter (Hi-Bolter) to obtain a white colorant (WT1).

[0511] (Production of white toner (WT2))

[0512] White toner (WT2) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 10 parts and the styrene acrylic resin was changed to 105 parts.

[0513] (Production of white toner (WT3))

[0514] White toner (WT3) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 99.2 parts and the styrene acrylic resin was changed to 15.8 parts.

[0515] (Production of white toner (WT4))

[0516] White toner (WT4) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 104 parts and the styrene acrylic resin was changed to 11 parts.

[0517] (Production of white toner (WT5))

[0518] White toner (WT6) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 108 parts and the styrene acrylic resin was changed to 7 parts.

[0519] (Production of white toner (WT6))

[0520] White toner (WT6) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 60 parts, the styrene acrylic resin was changed to 15 parts, and the white colorant was changed to 120 parts.

[0521] (Production of white toner (WT7))

[0522] White toner (WT7) was obtained in the same manner as white toner (WT1) except that the polyester resin was changed to 140 parts, the styrene acrylic resin was changed to 15 parts, and the white colorant was changed to 40 parts.

[0523] (Production of white toner (WT8))

[0524] White toner (WT8) was obtained in the same manner as white toner (WT1) except that all materials were added in the first kneading step and the second kneading step was not performed.

[0525] (Production of white toner (WT9))

[0526] White toner (WT9) was obtained in the same manner as in white toner (WT1) except that all materials were charged in the first kneading, the screw rotation speed in the first kneading was set to 500 rpm, and the second kneading step was not performed.

[0527] (Production of white toner (WT10))

[0528] White toner (WT10) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 115 parts and the styrene acrylic resin was changed to 0 parts.

[0529] (Production of white toner (WT11))

[0530] White toner (WT11) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 106 parts and the styrene acrylic resin was changed to 9 parts.

[0531] (Production of white toner (WT12))

[0532] White toner (WT12) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 85 parts and the styrene acrylic resin was changed to 30 parts.

[0533] (Production of white toner (WT13))

[0534] White toner (WT13) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 102.2 parts and the styrene acrylic resin was changed to 12.8 parts.

[0535] (Production of white toner (WT14))

[0536] White toner (WT14) was obtained in the same manner as in white toner (WT1) except that the polyester resin was changed to 92 parts and the styrene acrylic resin was changed to 23 parts.

[0537] (Production of white toner (WT101))

[0538] White toner particles (W101) were obtained by using 47.5 parts of polyester resin, 10 parts of styrene acrylic resin, and 80 parts of white colorant (MT1) as toner particle forming materials, setting the screw rotation speed in the kneading process to 500 rpm, setting the kneading setting temperature of kneading section 1 to 100° C., and setting the kneading setting temperature of kneading section 2 to 110° C., and not performing the second kneading process. In addition, the kneaded material temperature at the discharge port (discharge port 18) of the screw extruder 11 was 120° C.

[0539] - Addition of external additives -

[0540] 1.5 parts of hydrophobic silica (RY50 manufactured by Nippon Aerosil Co., Ltd.) and 1.2 parts of spherical silica treated with hexamethyldisilazane having an average particle size of 130 nm were added to the obtained white colorant particles (W101), mixed (external addition) for 10 minutes using a Henschel mixer, and then sieved at 45 μm using a wind sifter (Hi-Bolter) to obtain a white colorant (WT101).

[0541] (Production of white toners (WT102) to (WT116))

[0542] White toners (WT102) to (WT116) were obtained in the same manner as the white toner (WT101) except that the type and addition amount of the white colorant were changed to the white colorants (MT2) to (MT16) shown in Table 3.

[0543] (Production of white toner (WT117))

[0544] White toner (WT117) was obtained in the same manner as white toner (WT101) except that white colorant (MT1) was changed to white colorant (MT17).

[0545] <Examples 1 to 28, Comparative Examples 1 to 3>

[0546] A toner set of a cyan toner and a white toner shown in Table 1 was used as a toner set in each example.

[0547] Then, the cyan toner in the toner set of each example and the carrier (CA) obtained by the method described below were put into 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.

[0548] 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) = 8 / 92 and stirred for 20 minutes to obtain a white developer of each example.

[0549] Then, the obtained cyan developer and white developer were set as a developer set in each example.

[0550] - Preparation of vector (CA) -

[0551] 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 placed in 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.

[0552] - Preparation of Carrier (CB) -

[0553] 2.0 parts of cyclohexyl methacrylate resin (weight average molecular weight: 150,000), 0.6 parts of carbon black (VXC72) and 0.3 parts of melamine beads (Epostar S) were dissolved and mixed in 10 parts of toluene, and the resulting mixture was applied to 100 parts of ferrite cores with a volume average particle size of 35 μm to obtain a carrier (CB).

[0554] <Evaluation>

[0555] The following evaluations were performed using the developer sets of each example.

[0556] First, as an image forming apparatus, the developer of the developer set of each example was placed in a production printer "Iridesse Production Press Modified Machine (Fujifilm Business Innovation Co., Ltd.)".

[0557] Then, the following evaluation was performed using this image forming apparatus.

[0558] (Color Formation Evaluation of Colored Images A)

[0559] Under normal temperature and humidity (25°C, 50% RH) conditions, on A4-sized black paper (76.7 g / m 2 , Marubeni ForestLinX Co., Ltd.), with a white toner of 8g / m 2 , cyan toner is 4g / m 2 The loading amount is 1, and a 1-inch square (2.54 cm×2.54 cm) image is formed in the order of a white image and a cyan image from the side closest to the paper.

[0560] Then, the brightness (L* value) of the image was measured at three different locations on the same image using a spectrophotometric colorimetric system (Rite939, manufactured by X-Rite Corporation). The average value was used as the measured value, and the colorability of the colored image was evaluated based on the following evaluation criteria.

[0561] -Evaluation Criteria-

[0562] A: Brightness is above 70

[0563] B+: Brightness is above 67 and less than 70

[0564] B: Brightness is 65 or more and less than 67

[0565] C: Brightness is above 60 and less than 65

[0566] D: Brightness is 55 or more and less than 60

[0567] E: Brightness less than 55

[0568] (Friction evaluation of images)

[0569] The image obtained in the color formation evaluation A of the colored image was rubbed back and forth 10 times with a cotton cloth.

[0570] Then, the image defect after rubbing the image was evaluated. The evaluation was performed according to the following evaluation criteria.

[0571] A: No image roughness at all.

[0572] B+: Although slight image roughness is observed with a magnifying glass, it is not a problem.

[0573] B: Although the image is rough when observed with a magnifying glass, it is not a problem.

[0574] C: Although slight image roughness was visually confirmed, the level was not problematic.

[0575] D: The image is visually rough and is at a level that is problematic in practical use.

[0576] E: Image roughness is noticeably generated, which is a level that is problematic in practical use.

[0577] (Color quality evaluation of colored image B)

[0578] Under normal temperature and humidity (25°C, 50% RH) conditions, on A4-sized black paper (76.7 g / m 2 , Marubeni ForestLinX Co., Ltd., with a white toner of 6g / m 2 , cyan toner is 4g / m 2The loading amount is 1, and a 1-inch square (2.54 cm×2.54 cm) image is formed in the order of a white image and a cyan image from the side closest to the paper.

[0579] Then, the brightness (L* value) of the image was measured using a spectrophotometric colorimetric system (Rite 939, manufactured by X-Rite Corporation), and the color formation of the colored image was evaluated based on the following evaluation criteria.

[0580] -Evaluation Criteria-

[0581] A: Brightness is above 70

[0582] A-: Brightness is 68 or more and less than 70

[0583] B+: Brightness is above 65 and less than 68

[0584] B: Brightness is 62 or more and less than 65

[0585] C: Brightness is 56 or more and less than 62

[0586] D: Brightness below 55

[0587] (Folding resistance evaluation)

[0588] The image obtained in the color formation evaluation B of the color image was folded to perform a fold evaluation for determining the peeling state of the image.

[0589] Specifically, a sheet of paper having an image formed thereon was folded once and opened, the folded image was wiped with a cotton cloth, and the width of the image peeling off (peeling off in white) was defined as a crease value, and evaluation was performed according to the following criteria.

[0590] -Evaluation Criteria-

[0591] A: Crease value is less than 20μm

[0592] A-: Crease value is more than 20μm and less than 35μm

[0593] B+: Crease value is more than 35μm and less than 50μm

[0594] B: Crease value is more than 50μm and less than 80μm

[0595] C: Crease value is more than 80μm and less than 160μm

[0596] D: Crease value exceeds 160μm

[0597] Furthermore, the following characteristics of the white toner and the color toner (cyan toner in this embodiment) are shown in the table.

[0598] Content of vinyl resin relative to color toner particles: mass % (indicated as "StAc ratio CS" in the table)

[0599] Content of polyester resin relative to color toner particles: mass % (indicated as "PES ratio CP" in the table)

[0600] The mass ratio C of the polyester resin to the vinyl resin in the colored toner particles (denoted as PES / StAc ratio C")

[0601] Content of vinyl resin relative to white toner particles: mass % (indicated as "StAc ratio WS" in the table)

[0602] Content of polyester resin relative to white toner particles: mass % (indicated as "PES ratio WP" in the table)

[0603] The mass ratio W of the polyester resin to the vinyl resin in the white toner particles (denoted as PES / StAc ratio W")

[0604] Content of white colorant relative to white toner particles: mass % (indicated as "colorant amount" in the table)

[0605] The dispersion value P parameter of the white colorant measured by the division method on the cross section of the white toner particle (indicated as "colorant dispersion value P" in the table)

[0606] The area ratio of the white colorant when observing the cross section of the white toner particle (indicated as "colorant area ratio" in the table)

[0607] The number average particle size of the white colorant when observing the cross section of the white toner particles (indicated as "colorant particle size" in the table)

[0608] The ratio of the white colorant with a particle size of 100 nm or less to the total white colorant when observing the cross section of the white toner particles (indicated as "ratio of colorant with a particle size of 100 nm or less" in the table)

[0609] [Table 1]

[0610]

[0611] 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.

[0612] [Table 2-1]

[0613]

[0614] [Table 2-2]

[0615]

[0616] [Table 3]

[0617]

[0618] 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 the folding mark value is small in the folding resistance evaluation of the image. Therefore, the image with a colored image on the white image has high color quality and the peeling of the image during bending is suppressed.

[0619] (Note) (((1)))

[0621] A toner set for electrostatic charge image development, comprising:

[0622] A white toner having white toner particles including a polyester resin and a white colorant; and

[0623] a colored toner other than white, the colored toner having colored toner particles containing a vinyl resin, a polyester resin and a colored colorant,

[0624] A 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. (((2)))

[0626] The electrostatic image developing toner set according to (((1))), wherein:

[0627] 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)))

[0629] The electrostatic image developing toner set according to (((1))), wherein:

[0630] A dispersion value P parameter when the white colorant is measured by a division method on a cross section of the white toner particle is 0.85 or more and 1.00 or less. (((4)))

[0632] The electrostatic charge image developing toner set according to (((3))), wherein:

[0633] A dispersion value P parameter when the white colorant is measured by a division method on a cross section of the white toner particle is 0.90 or more and 1.00 or less. (((5)))

[0635] The electrostatic charge image developing toner set according to any one of (((1))) to (((4))), wherein

[0636] The white toner particles include a vinyl resin. (((6)))

[0638] The electrostatic image developing toner set according to (((5))), wherein:

[0639] 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. (((7)))

[0641] The electrostatic charge image developing toner set according to (((6))), wherein:

[0642] 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. (((8)))

[0644] The electrostatic charge image developing toner set according to any one of (((1))) to (((7))), wherein:

[0645] The content of the white colorant relative to the white toner particles is 20% by mass or more and 60% by mass or less. (((9)))

[0647] The electrostatic image developing toner set according to (((1))), wherein:

[0648] When observing a cross section of the white toner particle, the area ratio of the white colorant is 10% or more and 50% or less, and the number average particle size of the white colorant is 0.23 μm or more and 0.45 μm or less. (((10)))

[0650] The electrostatic charge image developing toner set according to (((9))), wherein:

[0651] When observing a cross section of the white toner particle, the area ratio of the white colorant is 20% or more and 50% or less, and the number average particle size of the white colorant is 0.23 μm or more and 0.30 μm or less. (((11)))

[0653] The electrostatic charge image developing toner set according to (((9))), wherein:

[0654] When observing a cross section of the white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to the entire white colorants is 30% by number or less. (((12)))

[0656] The electrostatic charge image developing toner set according to (((11))), wherein:

[0657] When observing a cross section of the white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to the entire white colorants is 20% by number or less. (((13)))

[0659] An electrostatic charge image developer set, comprising:

[0660] 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 (((12))); and

[0661] A colored electrostatic image developer containing the colored toner included in the electrostatic image developing toner set described in any one of (((1))) to (((12))). (((14)))

[0663] A toner cartridge set, comprising:

[0664] A white toner cartridge that stores the white toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((12))) and is attachable to and detachable from an image forming apparatus; and

[0665] A color toner cartridge stores the color toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((12))) and is attachable to and detachable from an image forming apparatus. (((15)))

[0667] A processing box, comprising:

[0668] a first developing unit that accommodates the white electrostatic charge image developer included in the electrostatic charge image developer group described in (((13))); and

[0669] a second developing unit, the second developing unit accommodating the colored electrostatic image developer contained in the electrostatic image developer group (((13))),

[0670] The process cartridge is attachable to and detachable from the image forming apparatus. (((16)))

[0672] An image forming device comprising:

[0673] a first image forming unit including a first developing unit that stores the white electrostatic image developer included in the electrostatic image developer set described in (((13))) and forms a white image using the white toner;

[0674] a second image forming unit including a second developing unit that stores the colored electrostatic image developer included in the electrostatic image developer set described in (((13))) and forms a colored image using the colored toner;

[0675] a transfer unit that transfers the white image and the colored image to a surface of a recording medium; and

[0676] A fixing unit fixes the white image and the color image transferred to the surface of the recording medium. (((17)))

[0678] An image forming method comprising:

[0679] a first image forming step of forming a white image using the white toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((12)));

[0680] a second image forming step of forming a color image using the color toner included in the electrostatic charge image developing toner set described in any one of (((1))) to (((12)));

[0681] a transfer step of transferring the white image and the color image to a surface of a recording medium; and a fixing step of fixing the white image and the color image transferred to the surface of the recording medium.

[0682] According to (((1))), 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 suppresses flaking of the colored image compared to the following colorant group for electrostatic charge image development: the colorant group for electrostatic charge image development 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 having colored colorant 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 colorant particles is less than 0.7 or exceeds 10.

[0683] 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 suppresses the peeling of the colored image compared to the following situation: the mass ratio C of the polyester resin to the vinyl resin in the colored toner particles is less than 2 or exceeds 6.

[0684] 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 suppresses flaking of the colored image compared to the following situation: on the cross section of the white colorant particles, the dispersion value P parameter when the white colorant is measured by the division method is less than 0.85 or exceeds 1.00.

[0685] According to (((4))), 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 suppresses flaking of the colored image compared to the following situation: the dispersion value P parameter of the white colorant measured by the division method on the cross section of the white colorant particles is less than 0.90 or exceeds 1.00.

[0686] According to (((5))), there is provided a toner set for developing an electrostatic image, which has high color formation of an image having a color image on a white image and suppresses peeling of the color image compared with a case where white toner particles contain only a polyester resin as a binder resin.

[0687] 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 suppresses peeling of the colored image, compared with the following situation: 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.

[0688] According to (((7))), a colorant group for electrostatic charge image development is provided, which has a high color formation of an image having a colored image on a white image and suppresses the peeling of the colored image compared to the following situation: 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.

[0689] According to (((8))), a toner 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 suppresses flaking of the colored image compared to the following situation: the content of white colorant relative to white toner particles is less than 20 mass% or exceeds 60 mass%.

[0690] According to (((9))), 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 suppresses image peeling during bending compared with the following colorant group for electrostatic charge image development: in the cross section of the white colorant particles, the area ratio of the white colorant is less than 10% or exceeds 50%, or the number average particle size of the white colorant is less than 0.23μm or exceeds 0.45μm.

[0691] According to (((10))), 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 suppresses image peeling during bending, compared with the following situation: when observing the cross-section of the white colorant particles, the area ratio of the white colorant is less than 20% or exceeds 50%, or the number average particle size of the white colorant is less than 0.23μm or exceeds 0.30μm.

[0692] According to (((11))), a colorant group for electrostatic charge image development is provided, which has a high degree of color formation of an image having a colored image on a white image and suppresses image peeling during bending, compared with the following situation: when observing the cross-section of the white colorant particles, the proportion of white colorants with a particle size of less than 100 nm relative to all white colorants exceeds 30% by number.

[0693] According to (((12))), a colorant group for electrostatic charge image development is provided, which has a high degree of color formation of an image having a colored image on a white image and suppresses image peeling during bending, compared with the following situation: when observing the cross-section of the white colorant particles, the proportion of white colorants with a particle size of less than 100 nm relative to the total white colorants exceeds 20%.

[0694] According to (((13))), (((14))), (((15))), (((16))), or (((17))), there is provided an electrostatic charge image developer group, a colorant box group, a processing box, an image forming device, or an image forming method, which has a high degree of color formation of an image having a colored image on a white image and suppresses peeling of the colored image compared to a case where the following electrostatic charge image developing colorant group is applied: the electrostatic charge image developing colorant group 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 having colored colorant 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 colorant particles is less than 0.7 or exceeds 10.

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 colored toner other than white, the colored toner having colored toner particles containing a vinyl resin, a polyester resin and a colored colorant, A 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.

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, wherein: A dispersion value P parameter when the white colorant is measured by a division method on a cross section of the white toner particle is 0.85 or more and 1.00 or less.

4. The electrostatic image developing toner set according to claim 3, wherein: A dispersion value P parameter when the white colorant is measured by a division method on a cross section of the white toner particle is 0.90 or more and 1.00 or less.

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

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 -0.6≤WC≤5.

6.

7. The electrostatic image developing toner set according to claim 6, 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.

8. The electrostatic image developing toner set according to any one of claims 1 to 7, wherein The content of the white colorant relative to the white toner particles is 20% by mass or more and 60% by mass or less.

9. The electrostatic image developing toner set according to claim 1, wherein: When observing a cross section of the white toner particle, the area ratio of the white colorant is 10% or more and 50% or less, and the number average particle size of the white colorant is 0.23 μm or more and 0.45 μm or less.

10. The electrostatic image developing toner set according to claim 9, wherein: When observing a cross section of the white toner particle, the area ratio of the white colorant is 20% or more and 50% or less, and the number average particle size of the white colorant is 0.23 μm or more and 0.30 μm or less.

11. The electrostatic image developing toner set according to claim 9, wherein: When observing a cross section of the white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to the entire white colorants is 30% by number or less.

12. The electrostatic image developing toner set according to claim 11, wherein: When observing a cross section of the white toner particles, the proportion of white colorants having a particle size of 100 nm or less relative to the entire white colorants is 20% by number or less.

13. 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 12; 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 12.

14. A toner cartridge set, characterized in that: include: a white toner cartridge, the white toner cartridge housing the white toner included in the electrostatic charge image developing toner set according to any one of claims 1 to 12, and being attachable to and detachable from an image forming apparatus; as well as A color toner cartridge that accommodates the color toner included in the electrostatic image developing toner set according to any one of claims 1 to 12 and is attachable to and detachable from an image forming apparatus.

15. A processing box, characterized in that: have: a first developing unit that accommodates the white electrostatic charge image developer included in the electrostatic charge image developer set according to claim 13; and a second developing unit, the second developing unit accommodating the colored electrostatic image developer contained in the electrostatic image developer set according to claim 13, The process cartridge is attachable to and detachable from the image forming apparatus.

16. An image forming device, characterized in that: have: a first image forming unit including a first developing unit storing the white electrostatic image developer contained in the electrostatic image developer set according to claim 13 and forming a white image using the white toner; a second image forming unit including a second developing unit that stores the colored electrostatic image developer contained in the electrostatic image developer set according to claim 13 and forms a colored image using 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.

17. 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 12; a second image forming step of forming a color image using the color toner included in the electrostatic charge image developing toner set according to any one of claims 1 to 12; 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