JP2020129043A - Method for forming images - Google Patents

Abstract

To provide a method for forming images with less unevenness.SOLUTION: The method for forming images according to the present invention includes the step of transferring and fixing white toner and colored toner on a recording medium at once and forming an image. The method satisfies the formula (1) of tanδw<tanδcwhen the dielectric loss tangent of the white toner is tanδwand the dielectric loss tangent of the colored toner is tanδcunder an environment of 20°C/50%RH and at 100 kHz.SELECTED DRAWING: None

Description

The present invention relates to an image forming method. More specifically, it relates to an image forming method with less image unevenness.

2. Description of the Related Art In recent years, in the field of electrostatic charge image developing toner used for electrophotographic image formation, development has been carried out in response to various demands from the market. In particular, the types of recording media used for printing are increasing, and there is a high demand from the market for the compatibility of printing machines with recording media. For example, when printing on a special recording medium such as colored paper, black paper, aluminum vapor-deposited paper, or transparent film, the color characteristics of the recording medium affect printing, so only colored toner showing yellow, magenta, cyan, black, etc. In that case, sufficient coloring cannot be obtained. Various technologies have been developed to meet such demands (see, for example, Patent Documents 1 and 2).

Patent Documents 1 and 2 describe a white toner formed in a lower layer or an upper layer of an image formed by combining a plurality of colored toners. By using the white toners described in Patent Documents 1 and 2, sufficient coloring is obtained by the color toner, and the added value of the image is improved.

However, when an image is formed by collectively transferring and fixing a white toner and a color toner onto a recording medium by using the techniques described in Patent Documents 1 and 2, the amount of toner placed on the recording medium is particularly large. In a solid image, deterioration of image quality due to image unevenness is a problem.

JP, 2002-311648, A JP, 2016-45418, A

The present invention has been made in view of the above problems and circumstances, and a problem to be solved is to provide an image forming method with less image unevenness.

In order to solve the above-mentioned problems, the present inventors set the dielectric loss tangent of a white toner, which is harder to transfer than a colored toner, lower than the dielectric loss tangent of a colored toner in the process of examining the causes of the above problems, and transfer efficiency is improved. The inventors have found that the unevenness of an image can be reduced by increasing the value, and have reached the present invention.
That is, the above-mentioned subject concerning the present invention is solved by the following means.

1. An image forming method including a step of forming an image by transferring and fixing a white toner and a color toner to a recording medium all together.
Environment of 20 ℃ · 50% RH, at 100kHz, the white toner dielectric loss tangent and tanδw _100k, and when the dielectric loss tangent of the color toner was tanδc _100k, images and satisfies the following formula (1) Forming method.
Formula (1) tan δw _100k <tan δc _100k

Environment of 2.20 ℃ · 50% RH, at 1 kHz, a dielectric loss tangent of the white toner and tanδw _1k, and when the dielectric loss tangent of the color toner and tanδc _1k, characterized by satisfying the following formula (2) The image forming method according to item 1.
Equation _{(2) tanδc 100k -tanδw 100k <} tanδc 1k -tanδw 1k

Environment of 3.20 ℃ · 50% RH, at 100kHz, the white toner dielectric loss tangent and tanδw _100k, and the dielectric loss tangent of the color toner and tanδc _100k, in 1 kHz, a dielectric loss tangent of the white toner and Tanderutadaburyu _1k And the dielectric loss tangent of the color toner is tan δc _1k , the image forming method according to the item 1 or 2, wherein the following formulas (3) and (4) are satisfied.
Formula (3) tan δw _1k <tan δw _100k
Formula (4) tan δc _1k >tan _{δc 100k}

4. 4. The image forming method according to any one of items 1 to 3, wherein the white toner and the colored toner contain a crystalline polyester resin.

5. 5. The crystalline polyester resin contains a hybrid crystalline polyester resin in which a crystalline polyester polymer segment and a vinyl polymer segment having a styrene-derived constitutional unit are chemically bonded to each other. Image forming method.

6. 6. The image forming method according to any one of items 1 to 5, wherein the white toner and the colored toner contain an amorphous vinyl resin.

7. The volume median diameter (Dw) of the toner base particles forming the white toner is larger than the volume median diameter (Dc) of the toner base particles forming the color toner. The image forming method according to any one of items 1 to 7.

8. Let Mg (w) (unit: kcps) be the content of Mg in the white toner represented by Net intensity by fluorescent X-ray analysis, and Mg in the colored toner represented by Net intensity by fluorescent X-ray analysis. The image forming method as described in any one of items 1 to 7, wherein the following expression (5) is satisfied when the content of is M(c) (unit: kcps).
Formula (5) M(c)/M(w)>15

By the above means of the present invention, it is possible to provide an image forming method with less image unevenness.
Although the mechanism of action or mechanism of action of the present invention has not been clarified, it is presumed as follows.

The white toner is generally used by placing more toner on the recording medium than the four-color YMCK toner in order to secure the concealing property of the recording medium, and forms an image in combination with the colored toner. In this case, more toner needs to be placed on the recording medium, and a stronger electric field is required in the transfer process in order to obtain high transfer efficiency. If the transfer current value is insufficient, sufficient transfer efficiency cannot be obtained and image unevenness occurs. When the transfer current value is excessive, electric charges are discharged in the transfer nip portion, which lowers transfer efficiency and causes image loss.

According to the present invention, when the white toner and the color toner are collectively transferred and fixed, the dielectric loss tangent of the white toner is set lower than the dielectric loss tangent of the color toner, so that high transfer efficiency of the white toner is ensured and image unevenness occurs. It is thought that this can be suppressed. That is, it is presumed that the mixture of the toners having different electric characteristics prevents the electric charge from concentrating on a certain place and suppresses the occurrence of the image unevenness due to the discharge phenomenon in the transfer process.

The image forming method of the present invention is an image forming method including a step of collectively transferring and fixing a white toner and a color toner onto a recording medium to form an image, in an environment of 20° C. and 50% RH, in 100kHz, the white toner dielectric loss tangent and tanδw _100k, and when the dielectric loss tangent of the color toner was tanδc _100k, and satisfies the formula (1). This feature is a technical feature common to or corresponding to each of the following embodiments (forms).

As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the dielectric loss tangent of the white toner at 1 kHz under an environment of 20° C. and 50% RH is tan δw _1k , and the dielectric loss tangent of the colored toner is tan δc. _When it is set to _1k , it is preferable that the formula (2) is satisfied from the viewpoint of manifesting the effect of the present invention.
Moreover, an environment of 20 ℃ · 50% RH, at 100kHz, the white toner dielectric loss tangent and Tanderutadaburyu _100k, and the dielectric loss tangent of the color toner and Tanderutashi _100k, in 1 kHz, a dielectric loss tangent of the white toner and Tanderutadaburyu _1k Further, when the dielectric loss tangent of the colored toner is tan δc _1k , it is more preferable from the viewpoint of manifesting the effects of the present invention that the above formulas (3) and (4) are satisfied.
Further, in the present invention, it is preferable that the white toner and the colored toner contain a crystalline polyester resin. As a result, the low-temperature fixability is excellent, and the discharge suppressing effect at the time of transfer is obtained, and the image unevenness suppressing effect is enhanced.

In an embodiment of the present invention, the crystalline polyester resin contains a hybrid crystalline polyester resin in which a crystalline polyester polymer segment and a vinyl polymer segment having a styrene-derived constitutional unit are chemically bonded, It is preferable because the dispersibility of the crystalline polyester resin in the amorphous resin, which is the main component of the composition, is improved and the discharge suppressing effect is excellent.
Further, in the present invention, it is preferable that the white toner and the colored toner contain an amorphous vinyl resin, which is excellent in dispersibility of the crystalline polyester and excellent in discharge suppressing effect.
As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the volume median diameter (Dw) of the toner base particles constituting the white toner is the volume median diameter of the toner base particles constituting the colored toner. It is preferable that it is larger than (Dc) from the viewpoint of transferability.
In addition, the content of Mg in the white toner represented by Net intensity by fluorescent X-ray analysis is M(w) (unit: kcps), and in the colored toner represented by Net intensity by fluorescent X-ray analysis When the content of Mg in M is set to M(c) (unit: kcps), it is preferable to satisfy the above formula (5) because the effect of suppressing image unevenness can be obtained.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning including the numerical value described before and after that as a lower limit and an upper limit.

The toner is basically a "chromatic toner" having three attributes of hue, lightness, and saturation, such as yellow toner, magenta toner, and cyan toner, and black toner, white toner, gray toner, and the like. Basically, it can be classified into “achromatic toner” which has no hue and saturation but only lightness, and “clear toner”.
The "clear toner" is a so-called "clear toner" in which a layer formed of the clear toner transmits almost the entire visible light region or a part of the visible light so that the other side of the layer can be seen through. Toner that becomes transparent. The light transmittance is not particularly limited as long as it can be seen through, but is 50% or more, preferably 70% or more, and more preferably 90% or more. In addition, when almost all light in the visible light region is transmitted, it becomes colorless and transparent.

In the present invention, the “white toner” means that when only the white toner is transferred onto a transfer material, the surface thereof is measured by a spectral color difference meter in accordance with JIS Z 8781-4:2013, CIE L ^* a ^*. Toner having a lightness L ^* in the b ^* color system of 80 or more and a color (white) satisfying the conditions of a ^* and b ^* of −10≦a ^* ≦10 and −10≦b ^* ≦10, respectively. Say.
Further, the "colored toner" referred to in the present specification means a toner belonging to a toner group including the chromatic toner and the black toner and the gray toner included in the achromatic toner, and the colored toner is white. Toner and clear toner are not included. That is, most commonly, a recording medium (for example, recording paper) is usually white, so that a chromatic color toner or a chromatic color toner that is recognized as different from the white color is used as a reference color. The black toner and the gray toner will be referred to as “colored toner” for convenience.

<<Outline of image forming method>>
The image forming method of the present invention is an image forming method including a step of collectively transferring and fixing a white toner and a color toner onto a recording medium to form an image, in an environment of 20° C. and 50% RH, in 100kHz, the white toner dielectric loss tangent and tanδw _100k, and when the dielectric loss tangent of the color toner was tanδc _100k, and satisfies the following formula (1).
Formula (1) tan δw _100k <tan δc _100k

[Dielectric loss tangent of toner]
In the present invention, since the dielectric loss tangent of the white toner and the color toner satisfies the expression (1), high transfer efficiency is ensured even when the images in which the white toner and the color toner are superimposed are collectively transferred. Moreover, it is possible to suppress the occurrence of image unevenness. It is considered that this is because the mixture of toners having different electric characteristics can prevent the electric charge from concentrating on a certain place and suppress the occurrence of image unevenness due to the discharge phenomenon in the transfer process.

more Tanderutashi _100k is large relative tanδw _100k, a large effect of suppressing image defects due to discharge at the time of transfer. Preferably, (tan δc _100k −tan δw _100k ) is more than 0.005, and more preferably more than 0.010.

When this value is 0 or negative, that is, when the dielectric loss tangent of the white toner is equal to or larger than the dielectric loss tangent of the color toner, the image unevenness is deteriorated. Since the resistance of the pigment used in the white toner is lower than that of the color toner and the specific gravity is larger than that of the color toner, it is difficult to transfer from the beginning, so in the above relationship, the difference in transferability between the white toner and the color toner is caused. It is thought that this is due to the fact that

It is preferable that the dielectric loss tangent of the white toner and the colored toner be established in a wide frequency range, and the dielectric loss tangent of the white toner is lower than the dielectric loss tangent of the colored toner in the measurement in the frequency range of 1 kHz to 100 kHz. It is preferable that it is strong against changes in the type of recording medium and the image forming environment. In particular, image unevenness due to the discharge phenomenon is less likely to occur even in a low-humidity environment where excessive charging is likely to occur.

Among them, under 20 ℃ · 50% RH environment, in 1 kHz, the dielectric loss tangent of the white toner and Tanderutadaburyu _1k, and when the dielectric loss tangent of the color toner and Tanderutashi _1k, satisfies the following formula (2) Is preferred.
Equation _{(2) tanδc 100k -tanδw 100k <} tanδc 1k -tanδw 1k

That is, it is preferable that the difference between the dielectric loss tangent of the white toner and the dielectric loss tangent of the colored toner is larger at 1 kHz than at 100 kHz.

It is preferable that this relationship be realized by further satisfying the following expressions (3) and (4).
Formula (3) tan δw _1k <tan δw _100k
Formula (4) tan δc _1k >tan _{δc 100k}

Equation (3) shows that the dielectric loss tangent of white toner increases as the frequency increases (that is, the frequency vs. dielectric loss tangent graph rises to the right), and equation (4) shows that the dielectric loss tangent of colored toner is Shows that becomes smaller as the frequency increases. (That is, the frequency vs. loss tangent graph goes down to the right)

Although the detailed mechanism is unknown, it is presumed that this is because the color toner having the characteristic that the dielectric loss tangent does not increase even in the high frequency region has a high discharge suppressing effect in the transfer process in combination with the white toner.

[Measurement of dielectric loss tangent]
The dielectric loss tangent of the toner can be measured as follows.
As a measurement sample, a predetermined amount of toner (3 g for white toner, 2 g for colored toner) was molded under a load of 100 kgf/cm ² for 10 seconds, and a disc-shaped sample of 40 mmφ (thickness: about 2 mm). To use. The thickness of the disc-shaped sample was measured with a caliper. The dielectric loss tangent tan δ can be measured using an LCR meter 65120P (manufactured by Toyo Technica Co., Ltd.) in an environment of a temperature of 20° C. and a relative humidity of 50% RH. Using the attached software WITNESS-6000, set the measurement frequency from 1 kHz to 100 kHz, set the number of single-digit points to 5 and the number of averaging to 3, and input the thickness of the disk-shaped sample for measurement. It can be performed.

<Image forming method>
The image forming method of the present invention can be carried out in the same manner as a known image forming method in the electrophotographic system, except that a combination of a white toner having a defined dielectric loss tangent and a toner containing at least one color toner is used.

For example, an electrostatic latent image electrostatically formed on an image carrier is made visible by charging a developer with a frictional charging member in a developing device to obtain a toner image (image forming layer), The toner image is transferred onto the recording medium. After that, the toner image transferred onto the recording medium is fixed on the recording material by a fixing process of a contact heating system, whereby a visible image is obtained.

Examples of fixing methods include so-called contact heating methods. Examples of the contact heating method include a heat and pressure fixing method, a heat roll fixing method, and a pressure contact heating and fixing method in which fixing is performed by a rotating pressure member containing a fixedly arranged heating body.

In the fixing method of the heat roll fixing method, usually, an upper roller provided with a heat source inside a metal cylinder made of iron or aluminum whose surface is coated with a fluororesin, and a lower roller formed of silicone rubber are used. Use the configured fixing device. A linear heater is used as a heat source, and the heater heats the surface temperature of the upper roller to about 120 to 200°C. A pressure is applied between the upper roller and the lower roller, and this pressure deforms the lower roller to form a nip.

The recording medium (also referred to as a recording material, a recording paper, a recording paper, etc.) may be a commercially available product, for example, as long as it holds a toner image formed by a known image forming method using an image forming apparatus or the like. Examples of recording media that can be used are plain paper from thin paper to thick paper, coated printing paper such as fine paper, art paper, and coated paper, commercially available Japanese paper and postcard paper, plastic film for OHP, cloth, and aluminum. Includes evaporated film, PET film and synthetic paper.

[toner]
The toner according to the present invention includes a white toner and a colored toner of at least one color. For example, all the toners of each color may be stored in the developing container of the developing device of each color of the full-color image forming apparatus, or a set of toner bottles of all colors that store toners of each color, It may be a set of process cartridges.

The toner according to the present invention preferably contains toner base particles containing a binder resin, a colorant and a release agent, and toner particles containing an external additive. The white toner base particles may be used as they are as white toner particles.
As a preferred embodiment of the binder resin according to the present invention, it is preferable that the white toner and the colored toner include an amorphous vinyl resin. The amorphous vinyl resin has excellent charging characteristics and excellent toner transfer.

Further, it is preferable that the white toner and the color toner contain crystalline polyester. It is considered that by including the crystalline polyester in the toner, the low-temperature fixability is excellent, and the crystalline polyester has a lower resistance than the amorphous resin, and therefore, the discharge suppressing effect at the time of transfer is excellent.

Furthermore, the crystalline polyester preferably contains a hybrid crystalline polyester resin in which a crystalline polyester polymerized segment and a vinyl polymerized segment having a constitutional unit derived from styrene are chemically bonded. By using the hybrid crystalline polyester resin, the dispersibility in the amorphous resin which is the main component of the toner is improved and the discharge suppressing effect is excellent.

[Colored toner]
Colored toner is an aggregate of colored toner particles. The colored toner particles include colored toner base particles.

<Binder resin>
The colored toner preferably contains an amorphous vinyl resin. The amorphous vinyl resin is a resin obtained by polymerization using at least a vinyl monomer. The amorphous vinyl resin includes acrylic resin and styrene-acrylic copolymer resin. From the viewpoint of suppressing the occurrence of filming, the amorphous vinyl resin is preferably a styrene/acrylic resin obtained by polymerizing a styrene monomer and an acrylic monomer.

The polymerizable monomer used for the styrene-acrylic resin is an aromatic vinyl monomer and a (meth)acrylic acid ester-based monomer, and is an ethylenic unsaturated bond capable of radical polymerization. Those having

Examples of aromatic vinyl monomers are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, p. -N-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2, 4-dimethylstyrene, 3,4-dichlorostyrene and the like and derivatives thereof are included. These aromatic vinyl monomers may be used alone or in combination of two or more.

Examples of (meth)acrylic acid ester-based monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, Butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, γ-aminoacrylate propyl, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate are included. These (meth)acrylic acid ester-based monomers may be used alone or in combination of two or more. In addition, it is preferable to use the styrene-based monomer and the acrylic acid ester-based monomer or the methacrylic acid ester-based monomer in combination.

A third vinyl-based monomer can also be used as the polymerizable monomer. Examples of the third vinyl monomer include acrylic acid, methacrylic acid, maleic anhydride, vinyl acetic acid and other acid monomers, and acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinyl. Pyrrolidone and butadiene are included.

As the polymerizable monomer, a polyfunctional vinyl-based monomer may be used. Examples of polyfunctional vinyl monomers include diacrylates such as ethylene glycol, propylene glycol, butylene glycol and hexylene glycol, and dimethacrylates and trimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol and trimethylolpropane. Is included. The copolymerization ratio of the polyfunctional vinyl-based monomer to the entire polymerizable monomer is preferably in the range of 0.001 to 5% by mass, more preferably 0.003 to 2% by mass, and 0.01 The range of 1 to 1% by mass is more preferable. The use of the polyfunctional vinyl-based monomer produces a gel component insoluble in tetrahydrofuran, but the proportion of the gel component in the entire polymer is preferably 40% by mass or less, more preferably 20% by mass or less.

When the crystalline polyester resin is contained in the toner, it is particularly preferable that the amorphous vinyl resin is contained in the toner in an amount of 30% by mass or more because the crystalline polyester is excellent in dispersibility and the discharge suppressing effect is obtained.

(Crystalline resin)
The colored toner particles preferably contain a crystalline resin from the viewpoint of obtaining excellent low-temperature fixability. The crystalline resin is a resin exhibiting crystallinity, and a known crystalline resin can be used. Here, “showing crystallinity” means having a melting point, that is, having a clear endothermic peak at the time of temperature rise in an endothermic curve obtained by DSC. Further, the “clear endothermic peak” means a peak having a half width within 15° C. in the endothermic curve when the temperature is raised at a heating rate of 10° C./min. A crystalline polyester resin is preferable as the crystalline resin.

It is considered that by including the crystalline polyester in the toner, the low-temperature fixability is excellent, and the crystalline polyester has a lower resistance than the amorphous resin, and therefore, the discharge suppressing effect at the time of transfer is excellent. The crystalline polyester is preferably contained in the toner within the range of 3 to 20% by mass from the viewpoint of the effect of suppressing discharge. When the content is within 20% by mass, the heat-resistant storage property of the toner does not deteriorate.

The crystalline polyester resin is a crystalline polyester resin obtained by a polymerization reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) monomer and a divalent or higher valent alcohol (polyhydric alcohol) monomer. Is referred to as a resin.

Examples of polycarboxylic acid monomers that can be used to synthesize the crystalline polyester resin include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecylsuccinic acid, 1,10-decane. Saturated aliphatic dicarboxylic acids such as dicarboxylic acid (dodecanedioic acid) and 1,12-dodecanedicarboxylic acid (tetradecanedioic acid); Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; Aroma such as phthalic acid, isophthalic acid and terephthalic acid Group dicarboxylic acids; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid; anhydrides of these carboxylic acid compounds and alkyl esters having 1 to 3 carbon atoms. These polyvalent carboxylic acid monomers may be used alone or in combination of two or more.

Examples of polyhydric alcohol monomers that can be used to synthesize the crystalline polyester resin include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1, Aliphatic diols such as 6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol and 1,4-butenediol; glycerin, pentaerythritol, trimethylolpropane , And polyhydric alcohols having 3 or more valences such as sorbitol are included. These polyhydric alcohol monomers may be used alone or in combination of two or more.

(Hybrid crystalline polyester resin)
Further, the crystalline polyester may include a hybrid crystalline polyester resin in which a crystalline polyester-based polymerized segment and a vinyl-based polymerized segment having a structural unit derived from styrene and a (meth)acrylic monomer are chemically bonded. preferable. It is considered that the hybrid crystalline polyester resin improves the dispersibility in the amorphous resin, which is the main component of the toner, and has an excellent discharge suppressing effect.

That is, the crystalline polyester resin may be a hybrid crystalline polyester resin (vinyl modified crystalline polyester resin) in which a vinyl resin segment and a crystalline polyester resin segment are bonded, and the vinyl resin segment is a styrene/acrylic resin segment. And the content ratio in the hybrid crystalline polyester resin is preferably in the range of 5 to 20% by mass. As a result, the dispersed particle size of the crystalline resin in the toner can be controlled to a desired value as described above.

The crystalline polyester resin segment refers to a molecular chain that constitutes the crystalline polyester resin. Further, the non-crystalline resin segment refers to a molecular chain that constitutes a non-crystalline resin (a resin that cannot have a crystalline structure).

The weight average molecular weight (Mw) of the hybrid crystalline polyester resin is preferably in the range of 5,000 to 100,000, and more preferably 7,000 to 50,000, from the viewpoint of reliably achieving sufficient low-temperature fixability and excellent long-term storage stability. Is more preferable, and it is particularly preferable that it is in the range of 8000-40,000.

When the weight average molecular weight (Mw) of the hybrid crystalline polyester resin is 100,000 or less, sufficient low temperature fixability can be obtained. On the other hand, by setting the weight average molecular weight (Mw) of the hybrid crystalline polyester resin to be 5,000 or more, it is possible to prevent the hybrid crystalline polyester resin and the non-crystalline resin from becoming excessively compatible with each other during toner storage. Therefore, it is possible to effectively suppress the image defect due to the fusion of the toner particles.

The weight average molecular weight (Mw) can be measured as follows.
Chloroform as an eluent is caused to flow at a flow rate of 1 mL per minute by using the following measuring device to stabilize the column in a constant temperature bath at 40°C. 100 μL of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. In the calibration curve at this time, several types of monodisperse polystyrenes with known molecular weights (manufactured by Tosoh Corporation; 2.63×10 ³ , 2.06×10 ⁴ , 1.02×10 ⁵ , manufactured by GL Sciences Inc.; 2.10×10 ³ , 7.00×10 ³ , 5.04×10 ⁴ ) prepared as a standard sample can be used.
Measuring device: "CO-8010" (manufactured by Tosoh Corporation)
Analytical column: "GMHXL" + "G3000HXL" (all manufactured by Tosoh Corporation)

(Crystalline polyester resin segment in hybrid crystalline polyester resin)
The crystalline polyester resin segment is a portion derived from a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol). In the differential scanning calorimetric measurement of the toner, it means a resin segment having the above-mentioned clear endothermic peak instead of the stepwise endothermic change.

The crystalline polyester resin segment is not particularly limited as long as it is as defined above.
For example, a resin having a structure in which a main chain of a crystalline polyester resin segment is copolymerized with another component, or a resin having a structure in which a crystalline polyester resin segment is copolymerized with a main chain of another component is included in this resin. If the toner exhibits a clear endothermic peak as described above, the resin corresponds to a hybrid resin having a crystalline polyester resin segment.

Further, the valences of the polyvalent carboxylic acid and the polyhydric alcohol are each preferably 2 to 3, and particularly preferably 2 respectively, and therefore, when the valence is 2 as a particularly preferable form (that is, dicarboxylic acid). The acid component and the diol component) will be described.
An aliphatic dicarboxylic acid is preferably used as the dicarboxylic acid component, and an aromatic dicarboxylic acid may be used in combination. As the aliphatic dicarboxylic acid, it is preferable to use a linear one. The use of the straight chain type has an advantage that the crystallinity is improved. The dicarboxylic acid component is not limited to one type, and two or more types may be mixed and used.

(Amorphous polyester resin)
When the main binder of the colored toner base particles is an amorphous vinyl resin, it is preferable to use an amorphous polyester resin, and the amorphous polyester resin is a hybrid amorphous in which a vinyl polymer segment and a polyester polymer segment are bonded. It is more preferable to use a hydrophilic polyester resin.

(Hybrid amorphous polyester resin)
A hybrid amorphous polyester resin is a resin in which a vinyl-based polymer segment composed of a styrene-acrylic polymer or the like and an amorphous polyester-based polymer segment composed of an amorphous polyester resin are chemically bonded. Is.

The content ratio of the vinyl-based polymerized segment in the hybrid amorphous polyester resin is preferably in the range of 5 to 30 mass% and more preferably in the range of 10 to 20 mass% with respect to the total mass of the hybrid amorphous polyester resin. preferable.

The amorphous polyester-based polymerized segment is a portion derived from a known polyester resin obtained by a polycondensation reaction with a polyvalent carboxylic acid component and a polyhydric alcohol component, and in a differential scanning calorimetry (DSC) of the toner, A polymerized segment in which no clear endothermic peak is observed.

Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid. , Fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucus acid, phthalic acid , Isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid , Diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenylsuccinic acid Acids: trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid and the like. These polyvalent carboxylic acids may be used alone or in admixture of two or more. Among these, it is preferable to use aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid and mesaconic acid, aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, succinic acid and trimellitic acid.
Examples of the polyhydric alcohol component include ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct. And dihydric alcohols such as glycerin, pentaerythritol, hexamethylol melamine, hexaethylol melamine, tetramethylol benzoguanamine and tetraethylol benzoguanamine. These polyhydric alcohol components may be used alone or in combination of two or more. Among these, dihydric alcohols such as bisphenol A ethylene oxide adducts and bisphenol A propylene oxide adducts are preferable.
The amorphous polyester polymerized segment is not particularly limited as long as it is as defined above. For example, regarding a resin having a structure in which the main chain of the amorphous polyester polymerized segment is copolymerized with another component, or a resin having a structure in which the amorphous polyester polymerized segment is copolymerized with the main chain of the other component, If the toner containing the resin does not have a clear endothermic peak as described above, the resin corresponds to the hybrid amorphous polyester resin having the amorphous polyester polymerized segment in the present invention.
The content of the amorphous polyester polymerized segment is preferably in the range of 75 to 98 mass% with respect to the total amount of the hybrid amorphous polyester resin. The constituent components and the content ratio of each segment in the hybrid amorphous polyester resin can be specified by, for example, NMR measurement and methylation reaction Py-GC/MS measurement.
The vinyl-based polymer segment can be prepared by using the monomers described in the above-mentioned amorphous vinyl resin.

<Release agent>
Wax may be added to the color toner base particles as a release agent. Examples of waxes that can be added are hydrocarbon waxes such as low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, paraffin wax, carnauba wax, pentaerythritol behenate, behenyl behenate. , Ester waxes such as behenyl citrate. These waxes may be used alone or in combination of two or more.

The melting point of the wax is preferably in the range of 50 to 95° C. from the viewpoint of reliably obtaining the low temperature fixability and releasability of the colored toner. The content ratio of the wax with respect to the total amount of the resin of the material of the color toner base particle precursor is preferably in the range of 2 to 20% by mass, more preferably in the range of 3 to 18% by mass, and in the range of 4 to 15% by mass. More preferable.

<Colorant>
Carbon black, a magnetic substance, a dye, a pigment or the like can be arbitrarily used as a colorant having a color other than white. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black. Examples of magnetic materials include ferromagnetic metals such as iron, nickel, and cobalt; alloys containing these metals; compounds of ferromagnetic metals such as ferrite and magnetite; Included are the alloys shown, for example, manganese-copper-aluminum, manganese-copper-tin, and other types of alloys called Heusler alloys, chromium dioxide.

Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black and lamp black, and magnetic powder such as magnetite and ferrite.

Examples of colorants for magenta or red include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48; 1, C.I. I. Pigment Red 53; 1, C.I. I. Pigment Red 57; 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 150, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, Pigment Red 184, C.I. I. Pigment Red 222 is included.

Further, examples of colorants for orange or yellow include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 185 is included.

Further, examples of colorants for green or cyan include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15;2, C.I. I. Pigment Blue 15;3, C.I. I. Pigment Blue 15; 4, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Blue 62, C.I. I. Pigment Blue 66, C.I. I. Pigment Green 7 is included.

These colorants may be used alone or in combination of two or more as needed.
From the viewpoint of ensuring color reproducibility of the image, the addition amount of the colorant is preferably in the range of 1 to 60% by mass, and more preferably in the range of 2 to 25% by mass with respect to the entire colored toner.
The volume average particle size of the colorant is preferably within the range of 10 to 1000 nm, more preferably within the range of 50 to 500 nm, and even more preferably within the range of 80 to 300 nm.

<Preparation Method of Colored Toner Base Particles>
The resin of the color toner base particles is preferably produced by an emulsion polymerization method.
Emulsion polymerization can be obtained by dispersing and polymerizing a polymerizable monomer such as styrene and acrylic acid ester in an aqueous medium. A surfactant is preferably used to disperse the polymerizable monomer in the aqueous medium, and a polymerization initiator and a chain transfer agent can be used for the polymerization.

As the polymerization initiator used for polymerizing the resin of the toner base particle precursor material, known polymerization initiators can be used. Examples of the polymerization initiator include hydrogen peroxide, acetyl peroxide, cumyl peroxide, -tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide. , Lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert-hydroperoxide, formic acid -Tert-butyl, per-acetate-tert-butyl, perbenzoate-tert-butyl, perphenylacetate-tert-butyl, permethoxyacetate-tert-butyl, perN-(3-toluyl)palmitate-tert-butyl Peroxides such as 2,2'-azobis(2-aminodipropane) hydrochloride, 2,2'-azobis-(2-aminodipropane) nitrate, 1,1'-azobis(1-methylbutyrate) Sodium ronitrile-3-sulfonate), 4,4'-azobis-4-cyanovaleric acid, and azo compounds such as poly(tetraethylene glycol-2,2'-azobisisobutyrate). The addition amount of the polymerization initiator varies depending on the desired molecular weight and molecular weight distribution, but specifically, it is preferably within the range of 0.1 to 5.0 mass% with respect to the polymerizable monomer.

A chain transfer agent may be added together with the polymerizable monomer in the production of the resin of the color toner base particles. The molecular weight of the polymer can be controlled by adding a chain transfer agent. In the polymerization step of polymerizing the above-mentioned aromatic vinyl monomer and (meth)acrylic acid ester monomer, a general chain transfer agent is used for the purpose of adjusting the molecular weight of the styrene/acrylic polymer segment. Can be used. Examples of chain transfer agents include alkyl mercaptans and mercapto fatty acid esters. The addition amount of the chain transfer agent varies depending on the desired molecular weight and molecular weight distribution, but specifically, it is preferably added in the range of 0.1 to 5.0 mass% with respect to the polymerizable monomer.

When the resin of the toner base particles is dispersed in an aqueous medium and polymerized by an emulsion polymerization method, a dispersion stabilizer is usually added to prevent aggregation of dispersed droplets. As the dispersion stabilizer, a known surfactant can be used, and a dispersion stabilizer selected from a cationic surfactant, an anionic surfactant, a nonionic surfactant and the like can be used. These surfactants may be used alone or in combination of two or more. The dispersion stabilizer can also be used in dispersion liquids such as colorants and anti-offset agents.

Examples of cationic surfactants include dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, and hexadecyl trimethyl ammonium bromide. Examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, norylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, styrylphenyl polyoxy. Includes ethylene ether and monodecanoyl sucrose. Examples of the anionic surfactant include aliphatic soaps such as sodium stearate and sodium laurate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and sodium polyoxyethylene(2) lauryl ether sulfate.

(Particle size of color toner base particles)
The particle diameter of the base particles of the color toner is preferably in the range of 4 to 10 μm when measured by the volume median diameter (volume-based median diameter) (D ₅₀ % diameter). For the volume median diameter (volume-based median diameter) (D ₅₀ % diameter) of the toner base particles, for example, an apparatus in which a computer system for data processing is connected to “Multisizer 3 (manufactured by Beckman Coulter, Inc.)” is used. Can be measured and calculated.

The measurement procedure is as follows: 0.02 g of toner particles is conditioned with 20 mL of a surfactant solution (for the purpose of dispersing the toner particles, for example, a neutral detergent containing a surfactant component is diluted 10 times with pure water). After that, ultrasonic dispersion is performed for 1 minute to prepare a toner particle dispersion liquid. This toner particle dispersion is pipetted into a beaker containing ISOTONII (manufactured by Beckman Coulter, Inc.) in a sample stand until the measured concentration is within the range of 5 to 10% by mass, and the number of measuring instruments is 25,000. Set to and measure. The multisizer 3 has an aperture diameter of 100 μm. The frequency number was calculated by dividing the measurement range of 1 to 30 μm into 256, and the particle diameter of 50% from the larger volume cumulative fraction was defined as the volume median diameter (volume-based median diameter) (D ₅₀ % diameter). To do.

(Circularity of color toner base particles)
The average value of the circularity of the color toner base particles is preferably in the range of 0.930 to 0.980. The average value of the circularity of the color toner base particles can be measured using a flow type particle image analyzer (FPIA-3000; Sysmex Co.). Specifically, the toner base particles are wetted with a surfactant aqueous solution, ultrasonically dispersed for 1 minute, dispersed, and then, using a flow-type particle image analyzer, under measurement condition HPF (high magnification imaging) mode, The measurement is performed at an appropriate concentration within the range of 3,000 to 10,000 HPF detections. Within this range, reproducible measurement values can be obtained. The circularity is calculated by the following formula (C).
Formula (C); circularity=(perimeter of circle having the same projected area as the particle image)/(perimeter of particle projected image)
Further, the average value of circularity is an arithmetic average value obtained by adding the circularity of each particle and dividing by the total number of particles measured.

[White toner]
The white toner is an aggregate of white toner particles, and the white toner particles include white toner base particles and an external additive. The white toner base particles have a binder resin and a white colorant. As the binder resin, the same resin as the binder resin in the color toner base particles can be used. Further, if necessary, a known additive may be contained as in the color toner.

The binder resin according to the present invention preferably contains an amorphous vinyl resin. The amorphous vinyl resin has excellent charging characteristics and excellent toner transfer. The white toner preferably contains crystalline polyester. It is considered that by including the crystalline polyester in the toner, the low-temperature fixability is excellent, and the crystalline polyester has a lower resistance than the amorphous resin, and therefore, the discharge suppressing effect at the time of transfer is excellent. Furthermore, the crystalline polyester preferably contains a hybrid crystalline polyester resin in which a crystalline polyester polymerized segment and a vinyl polymerized segment having a constitutional unit derived from styrene are chemically bonded. By using the hybrid crystalline polyester resin, the dispersibility in the amorphous resin which is the main component of the toner is improved and the discharge suppressing effect is excellent. As these resins, the same resins as those used in the color toner can be used.

Examples of white colorants include inorganic pigments (e.g., heavy calcium carbonate, light calcium carbonate, titanium oxide, aluminum hydroxide, titanium white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, Includes amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, smectite, etc.), organic pigments (eg polystyrene resin particles, urea-holimarin resin particles, etc.) Be done. Further, examples of the colorant also include pigments having a hollow structure such as hollow resin particles and hollow silica. The white colorant is preferably titanium oxide from the viewpoint of chargeability and hiding power. Titanium oxide may have any crystal structure such as anatase type, rutile type and brookite type.

(Particle size of white toner base particles)
The particle diameter of the base particles of the white toner is preferably in the range of _{5 to 20} μm when measured by the volume median diameter (volume-based median diameter) (D ₅₀ % diameter). Further, it is preferable that the volume median diameter (Dw) of the toner base particles constituting the white toner is larger than the volume median diameter (Dc) of the toner base particles constituting the color toner. That is, it is preferable that Dc<Dw is satisfied, and it is preferable that Dc and Dw satisfy the above relationship from the viewpoint of transferability.

Since the resistance of the pigment used in the white toner is lower than that of the color toner and the specific gravity is larger than that of the color toner, it is originally difficult to transfer. By increasing the particle size of the base particles of the white toner, the transferability of the white toner is improved.Therefore, by making the base particles of the white toner larger than the base particles of the colored toner, the difference in transferability is reduced. It is thought that it can be done. It is more preferable that 1.0<Dw/Dc<2.0.

The volume median diameter (volume-based median diameter) (D ₅₀ % diameter) of the toner base particles can be similarly measured and calculated using the apparatus described for the colored toner.
The measurement procedure is as follows: 0.02 g of toner particles is conditioned with 20 mL of a surfactant solution (for the purpose of dispersing the toner particles, for example, a neutral detergent containing a surfactant component is diluted 10 times with pure water). After that, ultrasonic dispersion is performed for 1 minute to prepare a toner particle dispersion liquid. This toner particle dispersion is pipetted into a beaker containing ISOTONII (manufactured by Beckman Coulter, Inc.) in a sample stand until the measured concentration is within the range of 5 to 10% by mass, and the number of measuring instruments is 25,000. Set to and measure. The multisizer 3 has an aperture diameter of 100 μm. The frequency number was calculated by dividing the measurement range of 1 to 30 μm into 256, and the particle diameter of 50% from the larger volume cumulative fraction was defined as the volume median diameter (volume-based median diameter) (D ₅₀ % diameter). To do.

(Circularity of white toner base particles)
The average value of the circularity of the white toner base particles is preferably in the range of 0.930 to 0.980. The average circularity of the white toner base particles can be measured by a method similar to that for colored toners, using a flow type particle image analyzer (FPIA-3000; Sysmex Co.).

(Content of Mg in white toner)
Further, in the white toner according to the present invention, the content of Mg in the white toner represented by Net intensity by fluorescent X-ray analysis is M(w) (unit: kcps), and the Net intensity by fluorescent X-ray analysis is When the content of Mg in the color toner represented is M(c) (unit: kcps), it is preferable that the following formula (5) is satisfied.
Formula (5) M(c)/M(w)>15
Although the reason is not clear, the larger the content of Mg in the color toner, the more effectively the image unevenness is suppressed.

The content of Mg in the toner can be controlled by the amount and timing of the metal salt aggregating agent used during toner production, the desorption reaction of metal ions by pH control, and the like.

The measurement of Net intensity by fluorescent X-ray analysis can be performed by using a fluorescent X-ray analyzer "XRF-1700" (manufactured by Shimadzu Corporation) to measure Net intensity of metal content. As a specific measuring method of the Net strength, 2 g of the toner is pressed under a load of 15 t for 10 seconds to be pelletized, and a qualitative quantitative analysis (see the following measurement conditions) is performed. The Kα peak angle of the sodium element to be measured can be determined and used from the 2θ table for the measurement.

-Measurement conditions-
Slit: Standard Attenuator: None Spectroscopic crystal (Na=TAP)
Detector (Na=FPC)
Tube voltage 40kV
Tube current 90mA

<Method for producing white toner and colored toner>
The white toner and the color toner can be manufactured by a known method. Examples of the method for producing the white toner and the colored toner include a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a solution suspension method, a polyester elongation method, and a dispersion polymerization method.
As a means for controlling the dielectric loss tangent, it is possible to control the dielectric loss tangent by the amount, the dispersion state, and the existing position of the crystalline resin or metal contained in the toner. The crystalline resin or metal can increase the dielectric loss tangent by being uniformly dispersed in the toner, and can exist in a portion near the surface layer of the toner to reduce the dielectric loss tangent at high frequencies. For example, when a toner is produced by an emulsion aggregation method, a crystalline resin or an aggregating agent is added to a portion close to the toner surface layer by adding a crystalline resin or an aggregating agent during the step of growing the particle diameter of the toner base. The larger the particle size of the toner base when the crystalline resin or the aggregating agent is added, the smaller the dielectric loss tangent at high frequencies tends to be.

A method for producing a toner by the kneading and pulverizing method will be described. The kneading and pulverizing method is a method in which at least a binder resin and a colorant are mixed, a kneading process is performed, and then a pulverizing process is performed to obtain a toner. Further, after the crushing treatment, if necessary, the classification treatment is performed using a known classification device or the like. Further, before the kneading treatment, the binder resin, the colorant, and if necessary, additives such as a release agent and a charge control agent may be sufficiently mixed with a mixer such as a Henschel mixer or a ball mill.

(1) Kneading process step As the kneading machine used for the kneading process, a general kneading machine such as a twin-screw extrusion kneading machine, a three-roll mill, and a lab blast mill can be used. Further, an internal additive may be added during the kneading process. It is preferable to heat at the time of kneading, and the heating conditions at this time can be appropriately set.
After heating and kneading, the mixture is usually cooled and the process proceeds to the crushing process of the next step. At this time, the cooling rate at the end of the kneading step may be set appropriately.

(2) Pulverizing Process As the pulverizing device used for the pulverizing process, a mechanical pulverizing device such as a turbo mill or an air flow type pulverizing device (jet mill) can be used. Further, before the crushing treatment, the kneaded material that has been cooled and solidified into chips in the kneading treatment may be roughly crushed by a hammer mill or a feather mill to a size such that it can be put into a crusher.

The toner particles obtained by the pulverization step may be classified by a classification step, if necessary, in order to obtain toner particles having a volume median diameter in a target range. In the classifying process, conventionally used gravity classifiers, centrifugal classifiers, inertia classifiers (classifiers utilizing the Coanda effect, etc.) are used, and fine powder (toner smaller than the particle size in the intended range) is used. Particles) and coarse powder (toner particles larger than the particle size in the intended range) are removed.

The volume median diameter of particles (hereinafter, also referred to as base particles) obtained after the pulverization treatment and the classification treatment in some cases is preferably in the range of 5 to 20 μm. The coefficient of variation (CV value) in the volume-based particle size distribution of the base particles is preferably within the range of 10-32. The coefficient of variation (CV value) in the volume-based particle size distribution represents the degree of dispersion in the particle size distribution of toner particles on the volume basis and is defined by the following formula.

CV value (%)=(standard deviation in number particle size distribution)/(median diameter in number particle size distribution (D50v))×100
When the toner is obtained by the kneading and pulverization method, the volume median diameter of the toner is determined by pulverization conditions (rotation speed of the pulverizer, pulverization time), classification conditions, processing conditions in the circularity control step described below, external additive addition step described below. It can be controlled by the processing conditions (rotating speed of the mixer, mixing time, etc.).

(3) Circularity control process (spheroidization process)
When the toner is obtained by the kneading and pulverization method, it is preferable to have a circularity control step for controlling the average circularity of the toner so as to satisfy the formula (C). At this time, it is preferable to perform the circularity control processing on at least the other toner among the other toners and the white toner, and it is preferable to perform the circularity control processing on both the other toner and the white toner. That is, in a preferred embodiment, the other toner (preferably, the other toner and the white toner) is subjected to a kneading process of mixing at least the binder resin and the colorant, and the resulting mixture is crushed. This is a form obtained by performing the circularity control process after performing the process.

Specific examples of the circularity control treatment include heat treatment of the base particles. The circularity can be controlled by the heating temperature and the holding time. The circularity can be close to 1 by increasing the heating temperature or increasing the holding time. However, since re-aggregation of toner particles and fusion between particles are promoted, it is not preferable to raise the heating temperature excessively. Further, since the domain structure inside the toner (arrangement other than the binder such as wax or crystalline polyester when the binder resin is used as a matrix) changes, it is not preferable to make the holding time excessively long.
The heating temperature in the circularity control treatment is preferably 70 to 95°C, more preferably 75 to 90°C.

The circularity control process may be performed by dry heating or wet heating. Wet heating is a method in which base particles are dispersed in an aqueous medium and heat treatment is performed. At this time, a surfactant or the like may be added for the purpose of improving the dispersion stability of the base particles. As the surfactant, alkylbenzene sulfonate, α-olefin sulfonate, anionic surfactant such as phosphate ester, alkylamine salt, aminoalcohol fatty acid derivative, polyamine fatty acid derivative, amine salt type such as imidazoline, Alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, quaternary ammonium salt type cationic surfactant such as benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, alanine, dodecyldi(aminoethyl)glycine, amphoteric surfactants such as di(octylaminoethyl)glycine and N-alkyl-N,N-dimethylammonium betaine, and the like, and also An anionic surfactant or a cationic surfactant having a fluoroalkyl group can also be used.

The method for producing toner particles by the kneading and pulverizing method may include the following (4) filtration/washing step, (5) drying step, and (6) external additive addition step after the circularity control treatment step. ..
(4) Filtration/Washing Step In this filtration/washing step, the obtained dispersion liquid of toner particles is cooled to obtain a slurry after cooling, and a solvent such as water is used from the cooled dispersion liquid of toner particles. A filtering process for solid-liquid separating the toner particles to separate the toner particles by filtration, and a cleaning process for removing deposits such as surfactants from the filtered toner particles (cake-like aggregates) are performed. .. Specific solid-liquid separation and washing methods include a centrifugation method, a vacuum filtration method using an aspirator, a Nutsche, etc., a filtration method using a filter press, etc., and these are not particularly limited. .. In this filtration/washing step, pH adjustment or pulverization may be appropriately performed. Such an operation may be repeated.

(5) Drying Step In this drying step, the washed toner particles are dried. The dryer used in this drying process includes an oven, a spray dryer, a vacuum freeze dryer, a vacuum dryer, a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary dryer, and a stirring dryer. A dryer and the like can be mentioned, but these are not particularly limited. The water content of the dried toner particles measured by the Karl Fischer coulometric titration method is preferably 5% by mass or less, and more preferably 2% by mass or less.

Further, in the case where the dried toner particles are aggregated by a weak interparticle attraction force to form an aggregate, the aggregate may be crushed. Here, as the crushing treatment device, a mechanical crushing device such as a jet mill, a co-mill, a Henschel mixer, a coffee mill and a food processor can be used.

(6) External Additive Addition Step In this external additive addition step, a charge control agent and various inorganic fine particles are added to the dried toner particles for the purpose of improving fluidity, chargeability and cleaning performance. This is a step of adding organic fine particles or an external additive such as a lubricant, and is performed as necessary. Examples of the apparatus used for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, a V-type mixer, and a sample mill. Further, in order to bring the particle size distribution of the toner into an appropriate range, sieving may be carried out if necessary.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” or “%” are used, but unless otherwise specified, “parts by mass” or “% by mass” is shown.

[Example 1]
<Method for producing amorphous polyester resin (AP1)>
In a reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas introduction tube, a monomer having the following composition and 0.25 part by mass of tin dioctylate per 100 parts by mass of the monomers having the following composition were charged. .. After reacting at 235° C. for 6 hours in a nitrogen gas stream, the temperature was lowered to 200° C. and the reaction was performed for 1 hour. The temperature was raised to 220° C. over 5 hours, and the mixture was polymerized under a pressure of 10 kPa until a desired molecular weight was obtained to obtain an amorphous polyester resin (AP1). The amorphous polyester resin (AP1) had a weight average molecular weight of 25,000 and a glass transition temperature of 55°C.

Bisphenol A ethylene oxide 2 mol adduct 50.2 parts by mass Bisphenol A propylene oxide 2 mol adduct 249.8 parts by mass Terephthalic acid 82.5 parts by mass Fumaric acid 32.0 parts by mass Dodecenyl succinic acid 32.0 parts by mass

<Method for producing amorphous polyester resin (AP2)>
A mixture of a monomer having a substituent that reacts with any of the following styrene acrylic resin monomers, amorphous polyester resins, and styrene acrylic resins and a polymerization initiator was placed in a dropping funnel.

Styrene 80.0 parts by mass n-butyl acrylate 20.0 parts by mass Acrylic acid 10.0 parts by mass Di-t-butyl peroxide (polymerization initiator) 16.0 parts by mass In addition, a single amount of the following amorphous polyester resin The body was placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve it.

Bisphenol A Propylene oxide 2 mol adduct 285.7 parts by mass Terephthalic acid 66.9 parts by mass Fumaric acid 47.4 parts by mass With stirring, the mixed solution placed in the dropping funnel was added dropwise to the four-necked flask over 90 minutes. After aging for 60 minutes, unreacted monomer was removed under reduced pressure (8 kPa).

Then, 0.4 parts by mass of titanium tetrabutoxide (Ti(OBu) ₄ ) was added as an esterification catalyst, the temperature was raised to 235° C., and the pressure was increased under normal pressure (101.3 kPa) for 5 hours and further under reduced pressure ( The reaction was carried out at 8 kPa) for 1 hour.

Then, the mixture was cooled to 200° C., the reaction was performed under reduced pressure (20 kPa), and then the solvent was removed to obtain an amorphous polyester resin (AP2). The weight average molecular weight of the amorphous polyester resin (AP2) was 25,000, and the glass transition temperature was 60°C.
The amorphous polyester resin (AP2) is a hybrid amorphous polyester resin in which a vinyl polymer segment and an amorphous polyester polymer segment are chemically bonded.

<Method for producing crystalline polyester resin (CP1)>
The following raw material monomers for the styrene acrylic polymerization segment and radical polymerization initiator were placed in a dropping funnel.

Styrene 36.0 parts by mass n-Butyl acrylate 13.0 parts by mass Acrylic acid 2.0 parts by mass Radical polymerization initiator (di-t-butyl peroxide) 7.0 parts by mass In addition, the raw material unit of the crystalline polyester polymerized segment is simple. The monomer was placed in a four-necked flask equipped with a nitrogen gas introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve it.

Tetradecanedioic acid 440 parts by mass 1,4-butanediol 153 parts by mass Then, the raw material monomer of the styrene acrylic polymerization segment is added dropwise over 90 minutes with stirring, and after aging for 60 minutes, under reduced pressure (8 kPa). The unreacted styrene acrylic polymer segment raw material monomer was removed. The amount of the raw material monomer removed at this time was very small with respect to the raw material monomer charged as described above. Then, 0.8 parts by mass of titanium tetrabutoxide (Ti(O-n-Bu) ₄ ) was added as a catalyst, the temperature was raised to 235°C, and the pressure was reduced under normal pressure (101.3 kPa) for 5 hours and further under reduced pressure. The reaction was carried out at (8 kPa) for 1 hour.

Then, after cooling to 200° C., a crystalline polyester resin (CP1) was obtained by reacting under reduced pressure (20 kPa) for 1 hour. The crystalline polyester resin (CP1) had a weight average molecular weight of 24500 and a melting point of 76°C.
The crystalline polyester resin (CP1) is a hybrid crystalline polyester resin in which a crystalline polyester resin is chemically bonded to a crystalline polyester polymer segment and a vinyl polymer segment having a styrene-derived constitutional unit.

<Method for producing amorphous vinyl resin (SP1)>
390 parts by mass of 0.1 mol/L Na ₃ PO ₄ aqueous solution was added to 1150 parts by mass of pure water, and the mixture was stirred by a mechanical disperser CLEARMIX (registered trademark) (manufactured by M Technique Co., Ltd.) at 10,000 rpm. 58 parts by mass of 1.0 mol/L CaCl ₂ aqueous solution was gradually added thereto to prepare a dispersion liquid containing Ca ₃ (PO ₄ ) ₂ .
The following compounds are mixed and dissolved to prepare a polymerizable monomer composition, and the polymerizable monomer composition is added to the dispersion liquid which is stirred at 6000 rpm with CLEARMIX, and further stirred for 20 minutes. Thus, a polymerizable monomer composition dispersion liquid in which droplets of the polymerizable monomer composition were dispersed was prepared.

Styrene 80 parts by mass n-butyl acrylate 20 parts by mass 2,2-azobis(2,4-dimethylvaleronitrile) 2.7 parts by mass This polymerizable monomer composition dispersion is stirred with a temperature sensor, a cooling pipe and The mixture was placed in a reaction vessel equipped with a nitrogen introduction tube, and the temperature in the reaction vessel was raised to 60° C. while stirring under a nitrogen stream to carry out a polymerization treatment for 5 hours. Further, the temperature inside the reaction vessel was raised to 80° C. to carry out a polymerization treatment for 5 hours, and then the reaction vessel was cooled to room temperature. Hydrochloric acid was added to the produced binder resin to dissolve Ca ₃ (PO ₄ ) ₂ and then washed with water, filtered and dried to prepare an amorphous vinyl resin (SP1). The amorphous vinyl resin (SP1) had a weight average molecular weight Mw of 32,000 and a glass transition temperature of 50°C.

<Method of manufacturing white toner W1>
(Particle size control process)
In a biaxial extrusion kneader, 507 parts by mass of an amorphous polyester resin (AP1) as a binder resin, 97.5 parts by mass of anatase type titanium oxide (volume average particle size 150 nm), and behenate behenate (release agent) , Melting point 73° C.) and kneading at 120° C. After kneading, it was cooled to 25°C.

Next, after coarsely pulverizing with a hammer mill, coarse powder is pulverized with a turbo mill pulverizer (manufactured by Turbo Kogyo Co., Ltd.), and fine powder classification treatment is further performed with an air stream classifier utilizing the Coanda effect, so that the volume-based median diameter is 8. 0 μm white host particles were produced.
(Circularity control process)
After adding a water dispersion medium in which 10 parts by mass of sodium dodecyl sulfate was dissolved in 500 parts by mass of ion-exchanged water and the obtained white base particles to a reaction vessel equipped with a stirrer, a temperature sensor and a cooling tube, the particle size was changed. The mixture was kept at 80° C. for 3 hours while stirring so as not to enter the cooling step when the circularity reached 0.927.

Next, solid-liquid separation and dehydration of the toner cake are redispersed in ion-exchanged water, and solid-liquid separation is repeated three times for washing. After washing, the white toner base particles were obtained by drying at 35° C. for 24 hours.

(External process)
To 100 parts by mass of the obtained white toner base particles, 0.6 parts by mass of hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68), hydrophobic titanium oxide particles (number average primary particle size: 20 nm) , Hydrophobicity: 63) 1.0 part by mass and sol-gel silica (number average primary particle size = 110 nm, 1.0 part by mass) were added, and a rotor blade peripheral speed 40 m/ It was mixed for 20 minutes at 32°C for sec. After mixing, coarse particles were removed by using a sieve having an opening of 45 μm to obtain a white toner W1.

<Production Method of White Toner W2>
White toner W1 was produced in the same manner as the white toner W1 except that 461.5 parts by mass of the amorphous polyester resin (AP1) and 45.5 parts by mass of the crystalline polyester resin (CP1) were used as the binder resin. Toner W2 was obtained.

<Method of manufacturing white toner W3>
As the binder resin, 230.8 parts by mass of the amorphous polyester resin (AP2), 45.5 parts by mass of the crystalline polyester resin (CP1), and 230.8 parts by mass of the amorphous vinyl resin (SP1) are used. A white toner W3 was obtained in the same manner as the method for producing the white toner W1 except that the above was used.

<Method of manufacturing white toner W4>
A white toner W4 was obtained in the same manner as the method for producing the white toner W3, except that the particle size of the white base particles in the particle size control step was 5.8 μm.

<Method for producing white pigment dispersion>
90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water. While stirring this solution, 700 parts by mass of anatase-type titanium oxide was gradually added, and then a dispersion treatment was performed using a mechanical disperser CLEARMIX (manufactured by M Technique Co., Ltd.) to disperse the colorant particles in an aqueous system. A liquid was prepared. The volume-based median diameter of the white pigment in the aqueous dispersion of the white pigment was 180 nm.

<Method for producing amorphous polyester resin (AP2) particle dispersion>
100 parts by mass of the amorphous polyester resin (AP2) was dissolved in 400 parts by mass of ethyl acetate, and mixed with 638 parts by mass of a 0.26% by mass sodium dodecylsulfate solution prepared in advance. While stirring the obtained mixed liquid, ultrasonic dispersion treatment was performed with an ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Co., Ltd.) at V-LEVEL 300 μA for 30 minutes.

Then, while heating to 40° C., a diaphragm vacuum pump V-700 (manufactured by BUCHI) was used to completely remove ethyl acetate while stirring under reduced pressure for 3 hours to obtain an amorphous polyester resin (AP2). ) A particle dispersion was prepared. The amorphous polyester resin (AP2) particles in the dispersion had a volume-based median diameter of 160 nm.

<Method for producing crystalline polyester resin (CP1) particle dispersion>
A crystalline polyester resin (CP1) particle dispersion was prepared in the same manner as the method for producing an amorphous polyester resin (AP2) particle dispersion, except that the resin used was a crystalline polyester resin (CP1). The crystalline polyester resin (CP1) particles in the dispersion had a volume-based median diameter of 160 nm.

<Method for producing amorphous vinyl resin (SP2) particle dispersion>
(First stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen gas introducing device was charged with 4 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of ion-exchanged water, while stirring at a stirring speed of 230 rpm under a nitrogen stream, while maintaining an internal temperature. Was heated to 80°C. After the temperature was raised, a solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, the liquid temperature was again adjusted to 80° C., and a mixed liquid of the following monomers was dropped over 2 hours.

Styrene 570.0 parts by mass n-Butyl acrylate 165.0 parts by mass Methacrylic acid 68.0 parts by mass After dropping the above mixed solution, polymerization is carried out by heating and stirring at 80° C. for 2 hours to obtain an amorphous vinyl resin. (SP2) Particle dispersion liquid (1-a) was prepared.

(Second-stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introducing device was charged with a solution prepared by dissolving 3 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate in 1210 parts by mass of deionized water and heated to 80°C. did. After heating, 60 parts by mass of the amorphous vinyl resin (SP2) particle dispersion liquid (1-a) prepared by the above-mentioned first-stage polymerization in terms of solid content, the following monomer, chain transfer agent and release agent were added. And the mixed solution dissolved at 80° C. were added.

Styrene (St) 245.0 parts by mass 2-ethylhexyl acrylate (2EHA) 97.0 parts by mass Methacrylic acid (MAA) 30.0 parts by mass n-octyl-3-mercaptopropionate 4.0 parts by mass Behenate behenate ( Release agent, melting point 73°C) 170.0 parts by mass

A mechanical dispersion machine CLEARMIX (registered trademark) (manufactured by M Technique Co., Ltd.) having a circulation path was mixed and dispersed for 1 hour to prepare a dispersion liquid containing emulsified particles (oil droplets). To this dispersion, a solution of a polymerization initiator in which 5.2 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water and 1000 parts by mass of ion-exchanged water were added, and the system was heated at 84° C. for 1 hour. Polymerization was carried out by heating and stirring for 2 hours to prepare an amorphous vinyl resin (SP2) particle dispersion liquid (1-b).

(Third stage polymerization)
A solution prepared by dissolving 7 parts by mass of potassium persulfate in 130 parts by mass of ion-exchanged water was added to the amorphous vinyl resin particle dispersion liquid (1-b) obtained by the second-stage polymerization. Furthermore, under a temperature condition of 82° C., a mixed solution of the following monomer and chain transfer agent was added dropwise over 1 hour.

Styrene (St) 350 parts by mass Methyl methacrylate (MMA) 50 parts by mass n-butyl acrylate (BA) 170 parts by mass Methacrylic acid (MAA) 35 parts by mass n-octyl-3-mercaptopropionate 8.0 parts by mass

After completion of the dropwise addition, the mixture was heated and stirred for 2 hours for polymerization, and then cooled to 28° C. to prepare an amorphous vinyl resin (SP2) particle dispersion liquid. The amorphous vinyl resin particles in the dispersion had a volume-based median diameter of 145 nm. The weight average molecular weight of the obtained amorphous vinyl resin (SP2) was 35,000, and the glass transition temperature (Tg) was 37°C.

<Method of manufacturing white toner W5>
442 parts by mass (solid content conversion) of the amorphous vinyl resin (SP2) particle dispersion prepared above, a crystalline polyester resin (CP1) particle dispersion, in a reaction vessel equipped with a stirrer, a temperature sensor and a cooling pipe. 45.5 parts by mass (as solid content), 97.5 parts by mass of white pigment dispersion (as solid content), and 500 parts by mass of ion-exchanged water were added, and a 5 mol/L sodium hydroxide aqueous solution was added. The pH was adjusted to 10. Further, a solution prepared by dissolving 60.8 parts by mass of magnesium chloride hexahydrate (coagulant 1) in 60.8 parts by mass of ion-exchanged water was added at 30° C. for 10 minutes while stirring. After standing for 3 minutes, the temperature was raised to 80° C. over 60 minutes. After reaching 80° C., the stirring speed was adjusted so that the particle size growth rate was 0.02 μm/min, and the volume-based median diameter measured by Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.) was 8.0 μm. At this point, the stirring speed was adjusted to stop grain size growth.

Next, 65 parts by mass of the amorphous polyester resin (AP2) particle dispersion liquid (solid content conversion) was added over 30 minutes, and when the supernatant of the reaction liquid became transparent, 50.7 parts by mass of sodium chloride was ionized. An aqueous solution dissolved in 250 parts by mass of exchanged water was added to stop the growth of particle size.

Next, the temperature was raised and the mixture was stirred at 80° C., and the reaction solution was heated to 10° C. at an average circularity of 0.970 using a flow-type particle image measuring device “FPIA-3000” (manufactured by Sysmex Corporation). It was cooled to 25° C. at a cooling rate of 1/min to obtain a dispersion liquid of toner base particles.

The resulting dispersion was subjected to solid-liquid separation, and the dehydrated toner cake was redispersed in ion-exchanged water at 35° C., and solid-liquid separation was repeated 3 times for washing. After washing, the toner base particles (volume-based median diameter of 8.0 μm) were obtained by drying at 35° C. for 24 hours.

To 100 parts by mass of the obtained toner base particles, 0.6 parts by mass of hydrophobic silica particles (number average primary particle size: 12 nm, degree of hydrophobicity: 68), hydrophobic titanium oxide particles (number average primary particle size: 20 nm, Hydrophobicity: 63) 1.0 part by mass and sol-gel silica (number average primary particle size: 110 nm, hydrophobicity: 63) 1.0 part by mass are added and rotated by a Henschel mixer (manufactured by Nippon Coke Industry Co., Ltd.). The blades were mixed at a peripheral speed of 40 m/sec for 20 minutes at 32°C. After mixing, coarse particles were removed by using a sieve having an opening of 45 μm to obtain a white toner W5.

<Method of manufacturing white toner W6>
A white toner W6 was obtained in the same manner as the white toner W5 except that the amount of magnesium chloride hexahydrate was changed to 80.8 parts by mass.

<Method for producing cyan pigment dispersion>
While stirring a solution prepared by adding 90 parts by mass of sodium dodecyl sulfate to 1600 parts by mass of ion-exchanged water, 420 parts by mass of "CI Pigment Blue 15:3" as a colorant was gradually added. A colorant particle dispersion liquid was prepared by performing a dispersion treatment using a stirring device CLEARMIX (manufactured by M Technique Co., Ltd., "CLEARMIX" is a registered trademark of the same company). The colorant particles in the dispersion had a volume-based median diameter of 110 nm.

<Method for producing colored toner C1>
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling pipe, 507 parts by mass (solid content) of the amorphous vinyl resin (SP2) particle dispersion prepared above and 32.5 parts by mass of a cyan pigment dispersion were prepared. (Solid content conversion), 500 parts by mass of ion-exchanged water was added, and a 5 mol/L sodium hydroxide aqueous solution was added to adjust the pH to 10. Further, a solution prepared by diluting 60.8 parts by mass of magnesium chloride hexahydrate (coagulant 1) with ion-exchanged water by a factor of 2 was added with stirring at 30° C. over 10 minutes. After standing for 3 minutes, the temperature was raised to 80° C. over 60 minutes. After reaching 80°C, a solution obtained by doubling 10 parts by mass of magnesium chloride hexahydrate (aggregating agent 2) with ion-exchanged water was added with stirring at 30°C for 10 minutes. After standing for 5 minutes, a solution obtained by mixing 45.5 parts by mass of the crystalline polyester resin (CP1) particle dispersion liquid (solid content conversion) with 10 parts by mass of dodecyldiphenyl ether disulfonic acid sodium salt (solid content conversion) for 30 minutes. When the supernatant of the reaction solution became transparent, the stirring speed was adjusted so that the growth rate of the particle size was 0.02 μm/min, and it was adjusted by Coulter Multisizer 3 (Beckman Coulter, Inc.). When the measured volume-based median diameter reached 5.8 μm, the stirring speed was adjusted to stop the particle size growth.

Next, 65 parts by mass of the amorphous polyester resin (AP2) particle dispersion liquid (solid content conversion) was added over 30 minutes, and when the supernatant of the reaction liquid became transparent, 50.7 parts by mass of sodium chloride was ionized. An aqueous solution dissolved in 250 parts by mass of exchanged water was added to stop the growth of particle size.
Next, the temperature was raised and the mixture was stirred at 80° C., and the reaction solution was heated to 10° C. at an average circularity of 0.970 using a flow-type particle image measuring device “FPIA-3000” (manufactured by Sysmex Corporation). It was cooled to 25° C. at a cooling rate of 1/min to obtain a dispersion liquid of toner base particles.

The resulting dispersion was subjected to solid-liquid separation, and the dehydrated toner cake was redispersed in ion-exchanged water at 35° C., and solid-liquid separation was repeated 3 times for washing. After washing, the toner base particles (volume-based median diameter 5.8 μm) were obtained by drying at 35° C. for 24 hours.

To 100 parts by mass of the obtained toner base particles, 0.6 parts by mass of hydrophobic silica particles (number average primary particle size: 12 nm, degree of hydrophobicity: 68), hydrophobic titanium oxide particles (number average primary particle size: 20 nm, Hydrophobicity: 63) 1.0 part by mass and sol-gel silica (number average primary particle size: 110 nm, hydrophobicity: 63) 1.0 part by mass are added and rotated by a Henschel mixer (manufactured by Nippon Coke Industry Co., Ltd.). The blades were mixed at a peripheral speed of 40 m/sec for 20 minutes at 32°C. After mixing, coarse particles were removed by using a sieve having an opening of 45 μm to obtain a color toner C1.

<Method for producing colored toner C2>
The amount of the amorphous vinyl resin particle dispersion is 507 parts by mass (solid content), the white pigment dispersion is 97.5 parts by mass (solid content), and the cyan pigment dispersion is 32.5 parts by mass (solid content). Further, a colored toner C2 was obtained in the same manner as in the manufacturing method of the white toner W5, except that the particle diameter of the toner base particles was changed to 5.8 μm.

<Method for producing colored toner C3>
Color toner C1 except that the amount of magnesium chloride hexahydrate (aggregating agent 1) was changed to 30.4 parts by mass and the amount of magnesium chloride hexahydrate (aggregating agent 2) was changed to 30.4 parts by mass. Color toner C3 was obtained in the same manner as in the manufacturing method.

<Method for producing colored toner C4>
Colored toner C4 was obtained in the same manner as in the method for producing colored toner C1 except that the amount of magnesium chloride hexahydrate (aggregating agent 2) was changed to 40.4 parts by mass.

<Method for producing colored toner C5>
Colored toner C5 was obtained in the same manner as in the method for producing colored toner C1 except that the amount of magnesium chloride hexahydrate (aggregating agent 2) was changed to 50.4 parts by mass.

<Method of manufacturing colored toner C6>
Anatase-type titanium oxide (volume average particle size 150 nm) 97.5 parts by mass was changed to “C.I. Pigment Blue 15:3” 32.5 parts by mass in the same manner as in the manufacturing method of the white toner W4, Colored toner C6 was obtained.

<Measurement of dielectric loss tangent>
As described above, measurement was performed using an LCR meter 65120P (manufactured by Toyo Technica Co., Ltd.) in an environment of a temperature of 20° C. and a relative humidity of 50% RH.

<Measurement of volume median diameter>
As described above, the volume median diameter was measured using Multisizer 3 (manufactured by Beckman Coulter, Inc.).

<Measurement of Mg content>
Net intensity of Mg content was measured using the above-mentioned fluorescent X-ray analyzer "XRF-1700" (manufactured by Shimadzu Corporation).

<Image unevenness evaluation method>
A commercially available full-color copying machine (bizhub PRESS C1060; Konica Minolta Co., Ltd.) was modified so that a white toner image forming unit was attached to the black position and a colored toner image forming unit was attached to the cyan position, and the development shown in the example table was performed. Each developer was charged into the developing machine in the developing means according to the combination of agents, and the following evaluations were performed.
Under the environment of a temperature of 10° C. and a humidity of 20% RH, a color is formed on the “POD gloss coated paper 128 g/m ² (manufactured by Oji Paper Co., Ltd.)” and on the white toner image (adhesion amount 10 g/m ² ). A solid image was formed by superposing toner images (adhesion amount: 5 g/m ² ) and the degree of occurrence of image unevenness was evaluated according to the following evaluation criteria.

(Evaluation criteria)
⊚: No image unevenness in solid image ◯: Slight image unevenness in solid image but no problem in practical use 〇 to △: Less unevenness than ◯, no unevenness in practical use △ : Poor than ◯ to △, but no problem in practical use ×: Uneven image is generated in a solid image, which is a problem in practical use

The above results are shown in Table I. In Table I, the arrow in the frequency dependence column indicates increase/decrease in the dielectric loss tangent of 100 k low frequency with respect to the dielectric loss tangent of 1 kHz under the environment of 20° C. and 50% RH. The upward-sloping arrow indicates that the dielectric loss tangent at 100 kHz is higher than the dielectric loss tangent at 1 kHz, and the downward-sloping arrow indicates that the dielectric loss tangent at 100 kHz is lower than the dielectric loss tangent at 1 kHz. The horizontal arrow pointing to the right indicates that the dielectric loss tangent did not change between 1 kHz and 100 kHz.

From Table I, it can be seen that in Examples 1 to 10 produced by the image forming method of the present invention, solid images have little image unevenness and are good.

Claims (8)

An image forming method including a step of forming an image by transferring and fixing a white toner and a color toner to a recording medium all together.
Environment of 20 ℃ · 50% RH, at 100kHz, the white toner dielectric loss tangent and tanδw _100k, and when the dielectric loss tangent of the color toner was tanδc _100k, images and satisfies the following formula (1) Forming method.
Formula (1) tan δw _100k <tan δc _100k Environment of 20 ℃ · 50% RH, at 1 kHz, a dielectric loss tangent of the white toner and tanδw _1k, and when the dielectric loss tangent of the color toner was tanδc _1k, and satisfies the following formula (2) The image forming method according to claim 1.
Equation _{(2) tanδc 100k -tanδw 100k <} tanδc 1k -tanδw 1k Environment of 20 ℃ · 50% RH, in 100kHz, the white toner dielectric loss tangent and Tanderutadaburyu _100k, and a Tanderutashi _100k a dielectric loss tangent of the color toner, in 1 kHz, a dielectric loss tangent of the white toner and Tanderutadaburyu _1k, and The image forming method according to claim 1 or 2, wherein when the dielectric loss tangent of the colored toner is tan δc _1k , the following formulas (3) and (4) are satisfied.
Formula (3) tan δw _1k <tan δw _100k
Formula (4) tan δc _1k >tan _{δc 100k} The image forming method according to any one of claims 1 to 3, wherein the white toner and the color toner contain a crystalline polyester resin. The crystalline polyester resin according to claim 4, wherein the crystalline polyester resin contains a hybrid crystalline polyester resin in which a crystalline polyester polymer segment and a vinyl polymer segment having a styrene-derived constitutional unit are chemically bonded. Image forming method. The image forming method according to any one of claims 1 to 5, wherein the white toner and the color toner contain an amorphous vinyl resin. 2. The volume median diameter (Dw) of the toner base particles forming the white toner is larger than the volume median diameter (Dc) of the toner base particles forming the color toner. 6. The image forming method according to any one of 6 to 6. Let Mg (w) (unit: kcps) be the content of Mg in the white toner represented by Net intensity by fluorescent X-ray analysis, and Mg in the colored toner represented by Net intensity by fluorescent X-ray analysis. The image forming method according to any one of claims 1 to 7, wherein the following formula (5) is satisfied, where M is the content of M(c) (unit: kcps).
Formula (5) M(c)/M(w)>15