JP6844553B2 - Toner and toner manufacturing method - Google Patents

Description

The present invention relates to toner and a method for producing toner.

For example, the toner described in Patent Document 1 contains toner particles including a toner core and a shell layer that covers the surface of the toner core. The shell layer contains a first shell resin and a second shell resin. The first shell resin is a hydrophobic thermoplastic resin. The second shell resin is a hydrophilic thermosetting resin.

JP-A-2017-9831

The toner described in Patent Document 1 is difficult to be charged and attenuated to some extent. However, it has been found by the study of the present inventor that there is room for improvement in that the toner is more difficult to be charged and attenuated to improve the charge retention property.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner having excellent heat-resistant storage stability and low-temperature fixability while improving charge retention. Another object of the present invention is to provide a method for producing a toner having excellent heat-resistant storage stability and low-temperature fixability while improving charge retention.

The toner according to the present invention contains toner particles. The toner particles include a toner core and a shell layer that covers the surface of the toner core. The toner core contains a binder resin having a carboxyl group. The shell layer contains a resin containing a unit having an oxazoline group and a unit having an amide bond. The ratio of the absorbance of the peak with ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance of the peak with ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy is greater than 0.00 and 0. It is 25 or less. The content of the shell layer with respect to the mass of the toner particles is 0.15% by mass or more and 0.40% by mass or less.

The method for producing a toner according to the present invention includes a step of reacting a toner core with a shell material and a ring-opening agent in an aqueous medium to form a shell layer covering the surface of the toner core to obtain toner particles. The shell material has an oxazoline group. The toner core contains a binder resin having a carboxyl group. The ring-opening agent has a carboxyl group. The shell layer contains a resin containing the unit having an oxazoline group and the unit having an amide bond. The ratio of the absorbance of the peak with ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance of the peak with ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy is greater than 0.00 and 0. It is 25 or less. The amide bond includes a first amide bond and a second amide bond. The first amide bond is formed by reacting the oxazoline group contained in the shell material with the carboxyl group contained in the binder resin contained in the toner core. The second amide bond is formed by the reaction of the oxazoline group of the shell material with the carboxyl group of the ring-opening agent. The content of the shell layer with respect to the mass of the toner particles is 0.15% by mass or more and 0.40% by mass or less.

The toner of the present invention is excellent in charge retention, heat storage and low temperature fixability. The toner produced by the production method of the present invention is excellent in charge retention, heat storage property and low temperature fixability.

It is a figure which shows an example of the cross-sectional structure of the toner particle contained in the toner which concerns on embodiment of this invention. FIG. 5 is a chromatograph diagram of toner particles measured using a pyrolysis gas chromatograph mass spectrometer (Py-GC / MS), and the toner particles are included in the toner according to the embodiment of the present invention. It is a figure which shows typically the reaction between the carboxyl group of the binder resin contained in a toner core, and the oxazoline group of a shell material. It is a figure which shows typically the reaction between the carboxyl group of a ring-opening agent, and the oxazoline group of a shell material. It is a graph which shows the calibration curve for calculating the shell layer content rate.

Evaluation results (values indicating shape or physical properties, etc.) of powders (more specifically, toner cores, toner particles, external additives, toners, etc.) were measured for a considerable number of particles unless otherwise specified. The average number of values. Further, the number average particle size of the powder is, unless otherwise specified, the number average value of the circle-equivalent diameters of the primary particles measured using a microscope. The equivalent circle diameter is the Haywood diameter, specifically the diameter of a circle having the same area as the projected area of the particles. If the measured value of the medium volume diameter (D ₅₀ ) of the powder is not specified, the Coulter principle (pore electric resistance method) is used by using "Coulter Counter Multisizer 4" manufactured by Beckman Coulter Co., Ltd. ) Is the value measured. The melting point (Mp) is a value measured using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) unless otherwise specified.

The strength of chargeability is the ease of triboelectric charging with respect to the standard carrier provided by the Imaging Society of Japan, unless otherwise specified. For example, the toner is triboelectrically charged by mixing with a standard carrier (anionic: N-01, cationic: P-01) provided by the Imaging Society of Japan and stirring. The surface potential of the measurement target is measured with, for example, KFM (Kelvin probe force microscope) before and after triboelectric charging, and it is shown that the measurement target having a larger change in potential before and after triboelectric charging has stronger chargeability.

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

[toner]
Hereinafter, embodiments of the present invention will be described. The present embodiment relates to toner. The toner contains toner particles. Toner is an aggregate (powder) of toner particles.

FIG. 1 shows an example of the cross-sectional structure of the toner particles 10 contained in the toner of the present embodiment. The toner particles 10 shown in FIG. 1 include a toner core 11 and a shell layer 12. The shell layer 12 covers the surface of the toner core 11. The shell layer 12 preferably covers the entire surface of the toner core 11, and more preferably completely covers the entire surface of the toner core 11. The structure of the toner particles contained in the toner has been described above with reference to FIG. Hereinafter, the toner will be further described.

<Absorbance ratio>
In the toner of the present embodiment, the shell layer contains a resin. Hereinafter, the "resin contained in the shell layer" may be referred to as "shell resin". The shell resin contains a unit having an oxazoline group and a unit having an amide bond. The oxazoline group in the unit having an oxazoline group contained in the shell resin is highly hydrophilic. Therefore, if the amount of the oxazoline group in the shell resin is too large, the toner particles are likely to be charged and attenuated, and the charge retention property of the toner is lowered. The charge retention property of the toner is a characteristic that the charge attenuation rate of the toner is slow (the charge attenuation constant is small), so that the toner particles are difficult to charge decay, and the charge amount of the toner can be maintained within a desired range. Charge attenuation of toner particles due to hydrophilic oxazoline groups is particularly likely to occur in a high temperature and high humidity environment. Here, in the toner of the present embodiment, the toner core contains a binder resin having a carboxyl group. The oxazoline group is ring-opened by the reaction between the carboxyl group of the binder resin and the oxazoline group of the shell resin. Further, when forming the shell layer of the toner of the present embodiment, for example, a ring-opening agent having a carboxyl group is added. The oxazoline group is ring-opened by the reaction between the carboxyl group of the ring-opening agent and the oxazoline group of the shell resin. Ring-opening of these oxazoline groups reduces the amount of oxazoline groups in the shell resin. Thereby, the amount of the highly hydrophilic oxazoline group can be adjusted within a desired range, the toner particles are less likely to be charged and attenuated, and the charge retention property of the toner can be improved. Further, a chemical bond (specifically, an amide bond) is formed between the toner core and the shell resin by reacting the carboxyl group of the binder resin with the oxazoline group of the shell resin. Therefore, it is possible to prevent the shell layer from peeling off from the toner core. The oxazoline group (unopened ring oxazoline group) has a cyclic structure and exhibits strong positive chargeability. The positive chargeability of the ring-opened oxazoline group is lower than that of the unopened oxazoline group.

The reaction between the oxazoline group and the carboxyl group of the shell resin opens the oxazoline group and forms an amide bond. By adjusting the amount of unopened oxazoline groups in the shell resin and the amount of oxazoline groups opened by reacting with the carboxyl group (corresponding to the amount of amide bond) within a desired range, the toner is charged. Sustainability can be improved. The ratio (A / B) of the absorbance (A) of the peak with ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance (B) of the peak with ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy is , Greater than 0.00 and less than 0.25. Hereinafter, the ratio (A /) of the absorbance (A) of the peak having ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance (B) of the peak having ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy. "B)" may be described as "IR ratio (A / B)".

The absorbance (A) of the peak derived from the oxazoline group indicates the amount of the unopened ring oxazoline group in the shell resin. The peak derived from the oxazoline group is a peak appearing at ^{a wave number of 1680 cm -1 in the infrared spectrum.} The absorbance (B) of the peak derived from the amide bond indicates the amount of the oxazoline group ring-opened by reacting with the carboxyl group (corresponding to the amount of the amide bond). The peak derived from the amide bond is a peak appearing at ^{a wave number of 1630 cm -1 in the infrared spectrum.} The IR ratio (A / B) represents the ratio "amount of unopened oxazoline groups / amount of ring-opened oxazoline groups".

When the IR ratio (A / B) is 0.25 or less, the amount of unopened oxazoline groups is appropriately reduced with respect to the amount of ring-opened oxazoline groups, and the toner particles are less likely to be charged and attenuated. Thereby, the charge retention property of the toner can be improved. Further, when the IR ratio (A / B) is 0.25 or less, the cleanability of the toner is also improved. When the amount of hydrophilic unopened ring oxazoline groups is appropriately reduced, it becomes difficult for the toner particles to absorb moisture, and the toner particles adhere to the member of the image forming apparatus (for example, the photoconductor drum or the cleaning part). This is because it can suppress. The lower limit of the IR ratio (A / B) is not particularly limited, but can be, for example, 0.15 or more. Two IR ratios (A / B) are selected from 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, and 0.25. It is also preferable that the value is within the range. The IR ratio (A / B) is 0.17 or more and less than 0.18, 0.18 or more and less than 0.20, 0.20 or more and less than 0.21, 0.21 or more and less than 0.22, 0.22. It may be more than 0.24 and less than 0.24, or more than 0.24 and less than 0.25. The IR ratio (A / B) may be 0.17, 0.19, 0.20, 0.21, 0.23, or 0.24.

The IR ratio (A / B) is measured by measuring the toner by the attenuated total reflection (ATR) method using a Fourier Transform Infrared Spectrometer (FT-IR). , Can be calculated by obtaining an IR spectrum. From the obtained IR spectrum, the absorbance (A) of the peak of ^{1680 cm -1} derived from the oxazoline group and the absorbance (B) of the peak of ^{1630 cm -1 derived from the amide bond are obtained.} Then, the IR ratio (A / B) is calculated according to the formula “IR ratio (A / B) = A / B”. The details of the method for measuring the IR ratio (A / B) will be described in detail in Examples.

Examples of the method for adjusting the IR ratio (A / B) to a desired value include the following first method, second method, and third method. The first method for adjusting the IR ratio (A / B) is a method of changing the amount of carboxyl groups of the binder resin contained in the toner core. As the amount of the carboxyl group of the binder resin contained in the toner core increases, the amount of the oxazoline group that reacts and opens the ring increases, so that the IR ratio (A / B) decreases. The amount of the carboxyl group of the binder resin contained in the toner core can be adjusted by changing the acid value of the binder resin. The higher the acid value of the binder resin, the greater the amount of carboxyl groups in the binder resin contained in the toner core.

The second method for adjusting the IR ratio (A / B) is a method of changing the addition amount of the material (shell material) for forming the shell layer with respect to the amount of the toner core. As the amount of the shell material added to the amount of the toner core increases, the amount of oxazoline groups contained in the shell material also increases, so that the IR ratio (A / B) increases.

The third method for adjusting the IR ratio (A / B) is a method of changing the amount of the ring-opening agent added when forming the shell layer. As the amount of the ring-opening agent added to the amount of the shell material (or the amount of the toner core) increases, the amount of the oxazoline groups that react and open the ring increases, so that the IR ratio (A / B) decreases.

The shell resin contains a unit having an oxazoline group. A preferable example of the unit having an oxazoline group is a unit represented by the following formula (A). Hereinafter, the "unit represented by the formula (A)" may be described as the "unit (A)".

In formula (A), R ¹ represents a hydrogen atom or an alkyl group which may have a substituent. Examples of the alkyl group represented by R ¹ include a methyl group, an ethyl group, and an isopropyl group. When R ¹ represents an alkyl group having a substituent, an example of such a substituent is a phenyl group. Preferable examples of R ¹ include a hydrogen atom, a methyl group, an ethyl group, and an isopropyl group.

The shell resin further contains a unit having an amide bond in addition to a unit having an oxazoline group. The unit having an amide bond preferably includes a unit having a first amide bond and a unit having a second amide bond.

The unit having the first amide bond includes the unit represented by the formula (B1). Hereinafter, the "unit represented by the formula (B1)" may be described as the "unit (B1)". The shell resin containing the unit (A) by reacting the oxazoline group of a part of the units (A) contained in the shell resin with the carboxyl group of the binder resin in the toner core. A unit (B1) can be further included in the unit (B1).

Wherein (B1), R ¹ represents the same group as R ¹ in formula (A), R ^B represents the atoms constituting the binder resin containing the toner core. R ^B is a constituent atom of the binder resin, the constituent atoms is bonded to a carboxyl group. Units of the shell layer (A) is a binder resin in the toner core (in the formula (B1) is represented by R ^B) by reacting with the carboxyl group of the oxazoline groups by ring-opening, the formula ( As shown in B1), the first amide bond is formed.

The unit having a second amide bond includes a unit represented by the formula (B2). Hereinafter, the "unit represented by the formula (B2)" may be described as the "unit (B2)". For example, in the shell resin containing the unit (A) by reacting the oxazoline group of a part of the units (A) contained in the shell resin with the carboxyl group of the ring-opening agent. Can further include the unit (B2).

Wherein (B2), R ¹ represents the same group as R ¹ in formula (A), R ² represents a 1 to 3 of alkyl group carbon atoms. As R ² , a methyl group or an ethyl group is particularly preferable. When acetic acid is used as the ring-opening agent for the oxazoline group, R ² becomes a methyl group.

As the ring-opening agent, short-chain fatty acids are preferable, acids ^{represented by the formula "R 2-} COOH" are more preferable, and acetic acid or propionic acid is further preferable. Incidentally, R ² in the formula "R ² -COOH" represents the same group as R ² in the formula (B2). By using such a ring-opening agent, the unit represented by the following formula (B2) can be further contained in the shell layer containing the unit (A) and the unit (B1).

The ring-opening agent is preferably water-soluble. When the ring-opening agent is water-soluble, the ring-opening agent can be suitably dissolved in the aqueous medium in the shell layer forming step described later, and the oxazoline group of the shell resin can be suitably opened. If R ² in the formula "R ² -COOH" represents 1 to 3 of alkyl group carbon atoms, water-soluble ring-opening agent is increased.

In an example of a method for confirming that the unit (A) in the shell layer is opened to form the units (B1) and (B2), the toner particles are measured by infrared spectroscopy and derived from the amide bond. Confirm the peak with a wave number of 1630 cm ^{-1 and} the peak with a wave number of 1680 cm ^{-1 derived from the oxazoline group.} A peak with a wave number of 1630 cm- ¹ derived from the amide bond indicates that the units (B1) and (B2) are present in the toner particles. A peak with a wave number of 1680 cm ^-1 derived from the oxazoline group indicates that the unit (A) is present in the toner particles. The measurement method by infrared spectroscopy is the same method as the measurement of the IR ratio (A / B) in the examples, or an alternative method thereof.

In another example of a method of confirming that the unit (A) in the shell layer is ring-opened to form the units (B1) and (B2), the ¹ H-NMR spectrum of the toner particles is measured. ^{1 In the 1} H-NMR spectrum, a triplet signal derived from a secondary amide appears near the chemical shift δ6.5. Therefore, ^{if a triple-line signal is confirmed in the vicinity of the chemical shift δ6.5 in the obtained 1} H-NMR spectrum, the unit (A) in the shell layer is opened and the units (B1) and (B2) are opened. Is presumed to have formed.

In order to ensure sufficient low temperature fixability of the toner, it is preferable that the toner core does not contain an oxazoline group.

<Shell layer content>
The content of the shell layer with respect to the mass of the toner particles is 0.15% by mass or more and 0.40% by mass or less. Hereinafter, "the content of the shell layer with respect to the mass of the toner particles" may be referred to as "the content of the shell layer". When the shell layer content is 0.15% by mass or more, the heat-resistant storage stability of the toner is improved. When the shell layer content is 0.40% by mass or less, the low temperature fixability of the toner is improved. In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, the shell layer content is preferably 0.20% by mass or more and 0.35% by mass or less. The shell layer content was 0.15% by mass, 0.16% by mass, 0.18% by mass, 0.20% by mass, 0.23% by mass, 0.29% by mass, 0.34% by mass, 0. It is also preferable that it is within the range of two values selected from 35% by mass, 0.36% by mass, 0.39% by mass, and 0.40% by mass. The shell layer content is 0.15% by mass or more and less than 0.18% by mass, 0.18% by mass or more and less than 0.20% by mass, 0.20% by mass or more and less than 0.29% by mass, 0.29. Mass% or more and less than 0.35% by mass, 0.35% by mass or more and less than 0.36% by mass, 0.36% by mass or more and less than 0.39% by mass, or 0.39% by mass or more and less than 0.40% by mass There may be. The shell layer content was 0.16% by mass, 0.18% by mass, 0.23% by mass, 0.29% by mass, 0.34% by mass, 0.36% by mass, or 0.39% by mass. You may.

The shell layer content is measured using a pyrolysis gas chromatograph mass spectrometer (Pyrolysis Gas Chromatographer Mass Spectrometer, ie Py-GC / MS). First, a calibration curve is prepared. The method for producing a calibration curve is the method described in Examples. Then, using Py-GC / MS, the toner particles are measured to obtain a chromatograph. FIG. 2 shows an example of a chromatograph of toner particles (each of 6 types of toner particles) measured using Py-GC / MS. The vertical axis in FIG. 2 indicates the signal strength, and the horizontal axis indicates the time (unit: minutes). In the obtained chromatograph, the peak area of the peak of the m / z value (m / z100 in FIG. 2) common to the shell material and the shell resin is calculated. Using the calibration curve, the toner shell layer content is calculated from the peak area of the peak of this m / z value. The toner particles showing a peak with a higher signal intensity have a higher shell layer content. The method for measuring the shell layer content will be described in detail in Examples.

Examples of the method for adjusting the shell layer content to a desired value include the following first method and second method.

The first method for adjusting the shell layer content is to change the amount of shell material added relative to the amount of toner core. The larger the amount of the shell material added to the amount of the toner core, the higher the shell layer content.

The second method for adjusting the shell layer content is to change the acid value of the toner core. The higher the acid value of the toner core, the more carboxyl groups are contained in the toner core. As the number of carboxyl groups increases, the number of reaction sites of the toner core that react with the oxazoline groups of the shell material increases. As the reaction site of the toner core increases, the amount of the shell material adhered to the toner core increases, so that the shell layer content increases. As described above, the acid value of the toner core can be adjusted, for example, by changing the acid value of the binder resin.

Next, the toner core and the shell layer will be further described. In addition, unnecessary components may be omitted depending on the use of the toner.

<Toner core>
In order to adjust the IR ratio (A / B) and the shell layer content to a desired range, the acid value of the toner core is preferably 5.0 mgKOH / g or more and 30.0 mgKOH / g or less, and 10.0 mgKOH. More preferably, it is / g or more and 20.0 mgKOH / g or less. The acid value of the toner core is, for example, 5.0 mgKOH / g or more and 9.0 mgKOH / g or less, 10.0 mgKOH / g or more and 15.0 mgKOH / g or less, or 25.0 mgKOH / g or more and 30.0 mgKOH or less. It may be less than / g. The acid value of the toner core may be, for example, 5.5 mgKOH / g, 13.4 mgKOH / g, or 29.6 mgKOH / g.

The method for measuring the acid value of the toner core is the method described in Examples or an alternative method thereof. The acid value of the toner core can be adjusted, for example, by changing the acid value of the binder resin contained in the toner core. The higher the acid value of the binder resin, the higher the acid value of the toner core.

The toner core contains a binder resin. The toner core may contain, for example, at least one of a colorant, a mold release agent, a charge control agent, and a magnetic powder, if necessary.

(Bundling resin)
The binder resin has a carboxyl group. Examples of the binder resin having a carboxyl group include a polyester resin. The toner core may contain one kind of binder resin having a carboxyl group, or may contain two or more kinds (for example, two kinds).

When the toner core contains two or more types (for example, two types) of a binder resin having a carboxyl group, the binder resin having a carboxyl group preferably contains a first polyester resin and a second polyester resin. The melting point of the first polyester resin is lower than the melting point of the second polyester resin. The acid value of the first polyester resin is higher than the acid value of the second polyester resin. Alternatively, the acid value of the first polyester resin is equal to the acid value of the second polyester resin. When the toner core contains the first polyester resin and the second polyester resin as the binder resin, it becomes easy to adjust the acid value of the toner core to a desired value. By adjusting the acid value of the toner core, the IR ratio (A / B) can be adjusted within a desired range.

The content of the first polyester resin with respect to the mass of the toner core is preferably higher than the content of the second polyester resin with respect to the mass of the toner core. The ratio of the mass of the first polyester resin to the mass of the second polyester resin is preferably greater than 1.0, more preferably 1.1 or more and 2.0 or less, and 1.1 or more and 1.5 or less. It is more preferable to have.

The acid value of the polyester resin is preferably 5 mgKOH / g or more and 50 mgKOH / g or less. When the toner core contains two types of the first polyester resin and the second polyester resin, the acid value of the first polyester resin is preferably 5 mgKOH / g or more and 50 mgKOH / g or less, and 7 mgKOH / g or more and 35 mgKOH / g or less. More preferably. The acid value of the second polyester resin is preferably 5 mgKOH / g or more and 50 mgKOH / g or less, and more preferably 5 mgKOH / g or more and 31 mgKOH / g or less. The acid value of the first polyester resin is 15 mgKOH / g and the acid value of the second polyester resin is 15 mgKOH / g; the acid value of the first polyester resin is 35 mgKOH / g and the acid value of the second polyester resin. Is 31 mgKOH / g; or more preferably, the acid value of the first polyester resin is 7 mgKOH / g and the acid value of the second polyester resin is 5 mgKOH / g.

The acid value of the polyester resin can be measured by a method conforming to JIS (Japanese Industrial Standards) K0070-1992. The acid value of the polyester resin can be adjusted, for example, by changing the type or amount of the carboxylic acid monomer used for synthesizing the polyester resin. The larger the number of carboxylic xyl groups contained in one carboxylic acid monomer, the higher the acid value of the synthesized polyester resin. The larger the amount of carboxylic acid monomer relative to the amount of alcohol monomer, the higher the acid value of the polyester resin.

The melting point (Mp) of the polyester resin is preferably 80 ° C. or higher and 130 ° C. or lower. When the toner core contains two types of a first polyester resin and a second polyester resin, the melting point of the first polyester resin is preferably 80 ° C. or higher and 100 ° C. or lower, and more preferably 92 ° C. The melting point of the second polyester resin is preferably higher than 100 ° C. and 130 ° C. or lower, and more preferably 121 ° C.

The glass transition point (Tg) of the polyester resin is preferably 80 ° C. or higher and 130 ° C. or lower. When the toner core contains two types of the first polyester resin and the second polyester resin, the glass transition point of the first polyester resin is preferably 40 ° C. or higher and 55 ° C. or lower, and more preferably 50 ° C. or lower. The glass transition point of the second polyester resin is preferably higher than 55 ° C. and 70 ° C. or lower, and more preferably 60 ° C. The glass transition point of the polyester resin can be adjusted, for example, by changing the type of alcohol monomer used for synthesizing the polyester resin.

The melting point and glass transition point of the polyester resin can be measured by obtaining the endothermic curve of the sample (polyester resin) using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Co., Ltd.). Specifically, 15 mg of the sample is placed in an aluminum plate, and the aluminum plate is set in the measuring unit of the measuring device. Use an empty aluminum dish as a reference. In the measurement of the endothermic curve, the temperature of the measurement unit is raised from the measurement start temperature of 10 ° C. to 150 ° C. at a rate of 10 ° C./min (RUN1). Then, the temperature of the measuring unit is lowered from 150 ° C. to 10 ° C. at a rate of 10 ° C./min. Subsequently, the temperature of the measuring unit is raised again from 10 ° C. to 150 ° C. at a rate of 10 ° C./min (RUN2). The endothermic curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) of the sample is obtained by RUN2. From the obtained endothermic curve, read the melting point and glass transition point of the sample. In the endothermic curve, the peak temperature due to the heat of fusion corresponds to the melting point of the sample. Further, in the heat absorption curve, the temperature (onset temperature) of the change point of the specific heat (the intersection of the extrapolation line of the baseline and the extrapolation line of the falling line) corresponds to the glass transition point of the sample.

The polyester resin is obtained by polycondensation or co-condensation of an alcohol monomer and a carboxylic acid monomer. The polyester resin is a polymer of an alcohol monomer and a carboxylic acid monomer.

Examples of alcohol monomers include diol monomers, bisphenol monomers, and trihydric or higher alcohol monomers.

Examples of diol monomers include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, propylene glycol, butanediol (eg, 1,4-butanediol), neopentyl glycol, Examples thereof include 2-butane-1,4-diol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. ..

Examples of bisphenol monomers include bisphenol A, hydrogenated bisphenol A, and alkylene oxide adducts of bisphenol A. Examples of alkylene oxide adducts of bisphenol A include bisphenol A ethylene adduct adducts and bisphenol A propylene oxide adducts.

Examples of trihydric or higher alcohol monomers include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol. , 1,2,5-pentantriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-triol Hydroxylmethylbenzene can be mentioned.

Examples of the carboxylic acid monomer include a divalent carboxylic acid monomer and a trivalent or higher carboxylic acid monomer.

Examples of divalent carboxylic acid monomers include maleic acid, fumaric acid, citraconic acid, succinic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, 5-sulfoisophthalic acid, sodium 5-sulfoisophthalate, cyclohexanedicarboxylic acid. , Adipic acid, sebacic acid, azelaic acid, malonic acid, succinic acid, alkylsuccinic acid, and alkenylsuccinic acid. Examples of alkyl succinic acid include n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, and isododecyl succinic acid. Examples of alkenyl succinic acid include n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, and isododecenyl succinic acid.

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

Only one kind of alcohol monomer may be used, or two or more kinds may be used. Only one kind of carboxylic acid monomer may be used, or two or more kinds may be used. Further, the carboxylic acid monomer may be derivatized into an ester-forming derivative and used. Examples of ester-forming derivatives include acid halides, acid anhydrides, and lower alkyl esters. The lower alkyl is, for example, an alkyl group having 1 to 6 carbon atoms.

The polyester resin is a carboxylic acid containing at least one of a diol monomer and a bisphenol monomer, a divalent carboxylic acid monomer, a trivalent carboxylic acid monomer, and a tetravalent carboxylic acid monomer. It is preferably a polymer with a monomer. The polyester resin contains an alcohol monomer containing at least one of an alkylene oxide adduct of bisphenol A, ethylene glycol, propylene glycol, and butanediol, and at least one of phthalic acid, trimellitic acid, and pyromellitic acid. It is more preferable that it is a polymer with a carboxylic acid monomer containing. The polyester resin is more preferably a polymer of an alkylene oxide adduct of bisphenol A, ethylene glycol, propylene glycol, butanediol, phthalic acid, trimellitic acid, and pyromellitic acid. The polyester resin is particularly preferably a polymer containing only the alkylene oxide adduct of bisphenol A, ethylene glycol, propylene glycol, butanediol, phthalic acid, trimellitic acid, and pyromellitic acid.

The binder resin may further contain a binder resin other than the polyester resin in addition to the polyester resin. Examples of binder resins other than polyester resins include styrene resins, acrylic acid resins (more specifically, acrylic acid ester polymers or methacrylic acid ester polymers, etc.), and olefin resins (more specifically). , Polyethylene resin, polypropylene resin, etc.), vinyl chloride resin, polyvinyl alcohol, vinyl ether resin, N-vinyl resin, polyamide resin, and urethane resin. Further, a copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the above resin (more specifically, a styrene-acrylic acid-based resin, a styrene-butadiene-based resin, or the like) is used. You may.

The content of the binder resin with respect to the mass of the toner core is preferably 30% by mass or more and 95% by mass or less, and more preferably 85% by mass or more and 95% by mass or less. When the toner core contains two or more kinds of binder resins, the content of the binder resins corresponds to the total content of two or more kinds of binder resins.

(Colorant)
The toner core may contain a colorant. As the colorant, a pigment or dye known according to the color of the toner can be used. In order to obtain a toner suitable for image formation, the amount of the colorant is preferably 1% by mass or more and 20% by mass or less with respect to the mass of the toner core.

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

The toner core may contain a color colorant. Examples of color colorants include yellow colorants, magenta colorants, and cyan colorants.

As the yellow colorant, for example, one or more compounds selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds can be used. Examples of yellow colorants include C.I. I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155 168, 174, 175, 176, 180, 181, 191 or 194), Naphthol Yellow S, Hansa Yellow G, and C.I. I. Bat yellow can be mentioned.

Examples of magenta colorants are selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. One or more compounds can be mentioned. Examples of magenta colorants include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177 , 184, 185, 202, 206, 220, 221 and 254).

Examples of the cyan colorant include one or more compounds selected from the group consisting of copper phthalocyanine compounds, anthraquinone compounds, and base dye lake compounds. Examples of cyan colorants include C.I. I. Pigment Blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66), Phthalocyanine Blue, C.I. I. Bat Blue, and C.I. I. Acid blue can be mentioned.

(Release agent)
The toner core may contain a release agent. In order to obtain a toner suitable for image formation, the amount of the release agent is preferably 3% by mass or more and 15% by mass or less with respect to the mass of the toner core.

Examples of the mold release agent include aliphatic hydrocarbon waxes (specifically, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymers, polyolefin waxes, microcrystallin waxes, paraffin waxes, Fishertropch waxes, etc.) and fats. Group hydrocarbon wax oxides (specifically, polyethylene oxide wax and its block copolymers, etc.), vegetable waxes (specifically, candelilla wax, carnauba wax, wood wax, jojoba wax, and rice). Waxes, etc.), animal waxes (specifically, mitsuro, lanolin, whale wax, etc.), mineral waxes (specifically, ozokelite, selecin, petrolatum, etc.), and waxes containing fatty acid esters as the main components. (Specifically, montanic acid ester wax, caster wax, etc.), wax in which a part or all of the fatty acid ester is deoxidized (specifically, deoxidized carnauba wax, etc.) can be mentioned. As the release agent, ester wax is preferable. The toner core may contain only one type of release agent, or may contain two or more types of release agents.

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

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

(Magnetic powder)
The toner core may contain magnetic powder. Examples of the material of the magnetic powder include ferromagnetic metals (specifically, iron, cobalt, nickel, and alloys thereof, etc.), ferromagnetic metal oxides (specifically, ferrite, magnetite, chromium dioxide, etc.) and the like. ), And a material that has been subjected to a ferromagnetization treatment (specifically, a carbon material to which ferromagnetism has been imparted by heat treatment, etc.). The toner core may contain only one kind of magnetic powder, or may contain two or more kinds of magnetic powder. In order to suppress the elution of metal ions (for example, iron ions) from the magnetic powder, it is preferable to surface-treat the magnetic powder.

<Shell layer>
The shell layer contains a shell resin. The shell layer is preferably a layer substantially composed of a shell resin. It is more preferable that the shell layer contains only the shell resin. In the toner of the present embodiment, the shell resin contains a unit having an oxazoline group. A suitable example of a unit having an oxazoline group is, for example, the unit (A). The unit (A) can be introduced into the shell resin by polymerizing the compound represented by the formula (1). Hereinafter, the "compound represented by the formula (1)" may be referred to as "compound (1)". In formula (1), R ¹ represents the same group as ^{R 1} in formula (A). ^{A preferred example of R 1} in formula (1) is the same as a preferred example ^{of R 1} in formula (A). When compound (1) is 2-vinyl-2-oxazoline, R ¹ in formula (1) is a hydrogen atom.

The unit (A) corresponds to a repeating unit, and the main chain of the shell layer is formed in the unit (A). A polymer (for example, a vinyl resin) is formed by polymerizing (addition polymerization) the "C = C" of the compound (1), which is a vinyl compound, into "-CC-". The vinyl compound is a compound having a vinyl group (CH ₂ = CH−) or a compound having a group in which a hydrogen atom in the vinyl group is substituted. In addition to the compound (1), a vinyl compound other than the compound (1) may be polymerized to obtain a polymer (for example, a vinyl resin). Examples of vinyl compounds other than compound (1) include ethylene, propylene, butadiene, vinyl chloride, (meth) acrylic acid, (meth) acrylic acid ester (preferably (meth) acrylic acid alkyl ester), acrylonitrile, and Examples include styrene.

The shell layer preferably contains a polymer of a monomer containing the compound (1) and the (meth) acrylic acid alkyl ester, and preferably contains a polymer of only the compound (1) and the (meth) acrylic acid alkyl ester. Is more preferable. It is more preferable that the shell layer contains only a polymer of a monomer containing the compound (1) and the (meth) acrylic acid alkyl ester. A polymer of a monomer containing compound (1) and a (meth) acrylic acid alkyl ester is a good example of a vinyl resin. The monomer is a raw material for the shell resin. The monomer that is the raw material of the shell resin may be only the compound (1) and the (meth) acrylic acid alkyl ester. Alternatively, the monomer as a raw material of the shell resin may further contain a compound other than the compound (1) and the (meth) acrylic acid alkyl ester in addition to the compound (1) and the (meth) acrylic acid alkyl ester.

Preferable examples of compound (1) include 2-vinyl-2-oxazoline. As the (meth) acrylic acid alkyl ester, methyl (meth) acrylate or ethyl (meth) acrylate is preferable, and methyl methacrylate is more preferable. The (meth) acrylic acid alkyl ester is a suitable example of a vinyl compound other than the compound (1). The addition of the (meth) acrylic acid alkyl ester tends to improve the coating property of the shell layer.

The shell layer may contain a basic substance, but preferably does not contain a basic substance. The basic substance is used as a pH adjuster, for example, in the shell layer forming step described later. Examples of the basic substance include ammonia and sodium hydroxide. By not adding a basic substance to the aqueous medium in the shell layer forming step, the neutralization (trap) of the carboxylic acid of the binder resin can be suppressed. This makes it easier to adjust the IR ratio (A / B) to a desired range. Further, the shell layer preferably does not contain a dispersant. In order to obtain a toner suitable for image formation, the thickness of the shell layer is preferably 10 nm or more and 100 nm or less.

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

In order to fully exert the function of the external additive while suppressing the detachment of the external agent particles from the toner particles, the amount of the external additive (when two or more kinds of external agent particles are used, the amount of the external agent particles is used. The total amount of the external additive particles) is preferably 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the toner particles. The average number of external additive particles is preferably 5 nm or more and 50 nm or less, and more preferably 10 nm or more and 35 nm or less.

As the external additive particles, inorganic particles are preferable, and silica particles or particles of metal oxide (specifically, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, etc.) are particularly preferable. preferable. However, as the external additive particles, particles of an organic acid compound such as a fatty acid metal salt (specifically, zinc stearate or the like) or resin particles may be used. The external additive particles may be surface-treated external additive particles, more specifically, external additive particles (positively charged silica particles) to which positive chargeability has been imparted by surface treatment. Only one kind of external additive particles may be provided on the surface of the toner particles, or two or more kinds of external additive particles may be provided.

The toner core is roughly classified into a crushed core and a polymerized core. The toner core obtained by the pulverization method belongs to the pulverized core, and the toner core obtained by the agglutination method belongs to the polymerized core. In the toner of the present embodiment, the toner core is preferably a pulverized core. The volume median diameter (D ₅₀ ) of the toner core is preferably 4 μm or more and 9 μm or less. The volume median diameter (D ₅₀ ) of the toner particles is preferably 4 μm or more and 9 μm or less.

The toner of this embodiment can be used for developing an electrostatic latent image, for example, as a positively charged toner. Toner may be used as a one-component developer. Further, the toner and the carrier may be mixed and the toner may be used as a two-component developer. In order to form a high-quality image, the amount of toner in the two-component developer is preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the carrier. The number of carriers The average primary particle diameter is preferably 20 μm or more and 120 μm or less. When the toner is a one-component developer, the toner is positively charged by rubbing against the developing sleeve or the toner charging member in the developing apparatus. The toner charging member is, for example, a doctor blade. In the case of a two-component developer containing a toner and a carrier, the toner is positively charged by being rubbed with the carrier in the developing apparatus.

The toner of the present embodiment can be used for forming an image in, for example, an electrophotographic apparatus (image forming apparatus). An example of an image forming method using an electrophotographic apparatus will be described. First, an electrostatic latent image is formed on the photosensitive layer of the photoconductor drum based on the image data. Next, the formed electrostatic latent image is developed using a positively charged toner (development step). In the developing step, the developing apparatus supplies the toner on the developing sleeve to the photosensitive layer of the photoconductor drum and attaches it to the electrostatic latent image by an electric force. In this way, the electrostatic latent image is developed, and a toner image is formed on the photosensitive layer of the photoconductor drum. Subsequently, the toner image is transferred to a recording medium (for example, paper), and then the unfixed toner image is fixed to the recording medium by heating (fixing step). As a result, the image is formed on the recording medium.

[Toner manufacturing method]
Next, a method for producing toner will be described. The method for producing toner includes a shell layer forming step. The toner manufacturing method may further include a toner core forming step and an external addition step, if necessary.

(Toner core forming process)
Examples of the method for forming the toner core include an agglutination method and a pulverization method.

An example of the pulverization method will be described. In the toner core forming step, the binder resin is mixed with an optional internal additive (for example, at least one of a colorant, a mold release agent, a charge control agent, and a magnetic powder). The obtained mixture is kneaded while being melted to obtain a kneaded product. The kneaded product is crushed to obtain a crushed product. The pulverized material is classified to obtain a toner core.

Hereinafter, an example of the agglutination method will be described. First, each fine particle of the binder resin, the mold release agent, and the colorant is aggregated in an aqueous medium to obtain aggregated particles containing the binder resin, the mold release agent, and the colorant. Subsequently, the obtained agglomerated particles are heated to coalesce the components contained in the agglomerated particles. As a result, a dispersion liquid of the toner core is obtained. After that, an unnecessary substance (surfactant or the like) is removed from the dispersion liquid of the toner core to obtain a toner core.

(Shell layer forming process)
The shell layer forming step is a step of forming a shell layer covering the surface of the toner core by reacting the toner core, the shell material, and the ring-opening agent in an aqueous medium to obtain toner particles.

The shell layer contains a resin containing a unit having an oxazoline group and a unit having an amide bond. The amide bond includes a first amide bond and a second amide bond. The shell material has an oxazoline group. As already mentioned, the toner core contains a binder resin having a carboxyl group. The first amide bond is formed by the reaction between the oxazoline group contained in the shell material and the carboxyl group contained in the binder resin contained in the toner core. As already mentioned, the shell material has an oxazoline group. The ring-opening agent has a carboxyl group. A second amide bond is formed by the reaction between the oxazoline group of the shell material and the carboxyl group of the ring-opening agent.

Hereinafter, an example of the shell layer forming step will be specifically described with reference to FIGS. 3 and 4. FIG. 3 schematically shows the reaction between the carboxyl group of the binder resin contained in the toner core 11 and the oxazoline group of the shell material 112. FIG. 4 schematically shows the reaction between the carboxyl group of the ring-opening agent 113 and the oxazoline group of the shell material 112. In FIGS. 3 and 4, the carbon atom (C) of the oxazoline group and the hydrogen atom (H) bonded to the carbon atom are omitted. The curves in the shell material 112 shown in FIGS. 3 and 4 schematically show the main chain of the shell material 112.

In an aqueous medium, the toner core 11 (toner core 11 obtained in the toner core forming step) and the shell material 112 (for example, an oxazoline group-containing water-soluble polymer) are mixed to obtain a dispersion liquid. Next, while stirring the dispersion liquid, the temperature of the dispersion liquid is raised to the first predetermined temperature at a predetermined temperature rising rate. The rate of temperature rise is preferably 0.1 ° C./min or more and 1.0 ° C./min or less, more preferably 0.5 ° C./min. The first predetermined temperature is preferably 45 ° C. or higher and 80 ° C. or lower, and more preferably 65 ° C. or lower. Then, the ring-opening agent 113 is added to the dispersion liquid. Next, the temperature of the dispersion liquid is adjusted to the second predetermined temperature. The second predetermined temperature is preferably 45 ° C. or higher and 80 ° C. or lower and the same temperature as the first predetermined temperature or lower than the first predetermined temperature, and more preferably 60 ° C. While stirring the dispersion liquid, the temperature of the dispersion liquid is maintained at a second predetermined temperature for a predetermined time. The predetermined time is preferably 0.1 hour or more and 3 hours or less, and more preferably 1 hour.

As shown in FIG. 3, the toner core 11 has a carboxyl group on its surface. The shell material 112 has an oxazoline group. While the dispersion is being heated or the dispersion is kept at a predetermined temperature, the carboxyl group of the toner core 11 and the oxazoline group of the shell material 112 react with each other to form the first amide bond 21. Further, as shown in FIG. 4, the ring-opening agent 113 has a carboxyl group. While the dispersion is kept at a predetermined temperature, the carboxyl group of the ring-opening agent 113 reacts with the oxazoline group of the shell material 112 to form a second amide bond 22. Further, along with the formation of the first amide bond 21 and the second amide bond 22, the reaction between the shell materials 112 proceeds to form the shell resin 114. As a result, the shell layer 12 (see FIG. 1) containing the shell resin 114 is formed on the surface of the toner core 11. The curve in the shell resin 114 shown in FIG. 4 schematically shows the main chain of the shell resin 114.

The shell resin 114 also has an oxazoline group (unopened ring oxazoline group 23) that has not reacted with the carboxyl group. By opening a part of the oxazoline group in this way to form the first amide bond 21 and the second amide bond 22, the IR ratio (A / B) is larger than 0.00 and 0.25. It can be adjusted as follows. The IR ratio (A / B) indicates the ratio of the amount of the unopened oxazoline group 23 to the total amount of the first amide bond 21 and the second amide bond 22 (corresponding to the amount of the ring-opened oxazoline group).

The case where the ring-opening agent 113 is added after raising the temperature of the dispersion liquid to a predetermined temperature has been described as an example. However, the timing of adding the ring-opening agent 113 is not particularly limited. The ring-opening agent 113 may be added before obtaining the dispersion. Specifically, the ring-opening agent 113 may be added at the same time as the shell material 112. Further, the ring-opening agent 113 is added once or a plurality of times before obtaining the dispersion liquid, during the temperature rise of the dispersion liquid, and at least one while keeping the temperature of the dispersion liquid at a predetermined temperature for a predetermined time. May be good.

As described above, referring to FIGS. 3 and 4, the reaction between the carboxyl group of the binder resin contained in the toner core 11 and the oxazoline group of the shell material 112, and the carboxyl group of the ring-opening agent 113 and the oxazoline group of the shell material 112. I explained the reaction with.

The shell material has an oxazoline group. Since the oxazoline group has high hydrophilicity, the shell material having an oxazoline group has high hydrophilicity. Therefore, the shell material is preferably dissolved in the aqueous medium. Thereby, the toner core, the shell material, and the ring-opening agent can be suitably reacted in the aqueous medium. The shell material preferably has a hydrophobic chain in addition to the oxazoline group. Since the oxazoline group has high hydrophilicity, it is possible to impart amphipathicity to the shell material by having a hydrophobic chain. Thereby, the shell material can function as a dispersant, and the shell material can be suitably reacted in an aqueous medium without using a dispersant (for example, a surfactant). In addition, the shell material can be suitably reacted in an aqueous medium without using an organic solvent. The hydrophobic chain is, for example, the main chain of the shell material. The hydrophobic chain is preferably, for example, an alkyl chain, and more preferably an alkyl chain derived from a vinyl group. The hydrophobic chain preferably does not contain a carbonyl group (> C = O) and an ether bond (−O−).

As the shell material, an oxazoline group-containing water-soluble polymer is preferable, and a polymer containing the unit (A) is more preferable. A commercially available product may be used as the shell material. Examples of commercially available products that can be used as shell materials include "Epocross (registered trademark) WS-300" and "Epocross (registered trademark) WS-700" manufactured by Nippon Shokubai Co., Ltd.

In the toner particles obtained in the shell layer forming step, the shell layer content is 0.15% by mass or more and 0.40% by mass or less. It is preferable to adjust the amount of the toner core and the amount of the solid content of the shell material so that the shell layer content is in such a range. For example, the solid content of the shell material is preferably 0.30% by mass or more and 1.20% by mass or less, and 0.35% by mass or more and 1.00% by mass or less with respect to the mass of the toner core. Is more preferable. When the amount of the solid content of the shell material with respect to the mass of the toner core is 0.30% by mass or more, the shell material can be suitably used as a dispersant, and aggregation of the shell material can be suppressed. When the amount of the solid content of the shell material with respect to the mass of the toner core is 1.20% by mass or less, the shell layer formed becomes thin, and the low temperature fixability of the toner can be improved.

The total content of the solid content of the shell material and the toner core with respect to the mass of the dispersion liquid is preferably 20% by mass or more and 60% by mass or less, and more preferably 45% by mass or more and 55% by mass or less.

By changing the amount of the ring-opening agent, the amount of the oxazoline group can be adjusted, and the IR ratio (A / B) can be adjusted within a desired range. In order to adjust the IR ratio (A / B) to a desired range, the mass of the ring-opening agent with respect to the mass of the toner core is preferably 0.07% by mass or more and 0.28% by mass or less. In order to adjust the IR ratio (A / B) to a desired range, the number of moles of carboxyl groups contained in the ring-opening agent should be 50 mol% or more of the number of moles of oxazoline groups contained in the shell material. , It is preferable to add a ring-opening agent.

The aqueous medium is a medium containing water as a main component (specifically, pure water, a mixed solution of water and a polar medium, or the like). As the polar medium in the aqueous medium, for example, alcohol (specifically, methanol, ethanol, etc.) can be used. The boiling point of the aqueous medium is about 100 ° C. It is preferable that no dispersant is added to the aqueous medium. As described above, since the shell material functions as a dispersant, the reaction of the shell material can proceed in the aqueous medium even when the dispersant is not added. Further, it is preferable not to add a basic substance to the aqueous medium. By not adding a basic substance to the aqueous medium, the neutralization (trap) of the carboxylic acid of the binder resin can be suppressed. Thereby, the IR ratio (A / B) can be adjusted to a desired range.

After keeping the dispersion at a predetermined temperature for a predetermined time, the dispersion is cooled. Subsequently, toner particles are obtained by solid-liquid separation (for example, filtration). After that, the toner particles may be washed and the washed toner particles may be dried.

(External process)
The toner particles and the external additive (for example, powder of silica particles) are mixed using a mixer (for example, FM mixer manufactured by Nippon Coke Industries Co., Ltd.) to attach the external additive to the surface of the toner particles. .. When a spray dryer is used in the drying step, the drying of the toner particles and the external addition step can be performed at the same time by spraying the dispersion liquid of the external additive onto the toner particles.

The contents and order of the toner manufacturing methods can be arbitrarily changed according to the required toner configuration or characteristics. For example, the material (eg, shell material, toner core, or ring-opening agent) may be added to the aqueous medium at once, or may be added to the aqueous medium in multiple batches. For example, the toner particles may be sieved after the external addition step. Further, unnecessary steps may be omitted. For example, when a commercially available product can be used as it is as a material, the step of preparing the material can be omitted by using the commercially available product. If the external additive is not required, the external addition step may be omitted. The method for producing the toner of this embodiment has been described above.

The present invention will be described in more detail with reference to Examples. The present invention is not limited to the scope of the examples. Table 1 shows the compositions of toners A-1 to A-7 and B-1 to B-6 according to Examples or Comparative Examples.

In Table 1, "polyester 1", "polyester 2", "AV", "Mp", "Tg", "part" and "wt%" are the first polyester resin, the second polyester resin, and the acid value, respectively. Indicates the melting point, glass transition point, parts by mass, and% by mass. In Table 1, "amount of shell material" indicates the amount of shell material (specifically, an oxazoline group-containing polymer aqueous solution) added to 100 parts by mass of the toner core. In Table 1, "amount of acetic acid" indicates the amount of acetic acid aqueous solution added to 100 parts by mass of the toner core. In Table 1, "shell layer content" indicates the content of the shell layer with respect to the mass of the toner particles. In Table 1, "IR ratio (A / B)" is the ratio (A) of the absorbance (A) of the peak derived from the oxazoline group to the absorbance (B) of the peak derived from the amide bond, which is measured by infrared spectroscopy. / B) is shown.

Hereinafter, the manufacturing method, the measuring method, the evaluation method, and the evaluation result of the toners A-1 to A-7 and B-1 to B-6 will be described. In the evaluation in which an error occurs, a considerable number of measured values in which the error is sufficiently small are obtained, and the average number of the obtained measured values is used as the evaluation value.

[Toner manufacturing method]
As the first polyester resin contained in the toner core, polyester resins (1-1) to (1-4) having the following physical characteristics were used.
Polyester resin (1-1): AV15 mgKOH / g, Mp92 ° C, Tg50 ° C
Polyester resin (1-2): AV35 mgKOH / g, Mp92 ° C, Tg50 ° C
Polyester resin (1-3): AV7 mgKOH / g, Mp92 ° C, Tg50 ° C
Polyester resin (1-4): AV4 mgKOH / g, Mp92 ° C, Tg50 ° C

As the second polyester resin contained in the toner core, polyester resins (2-1) to (2-4) having the following physical characteristics were used.
Polyester resin (2-1): AV15 mgKOH / g, Mp121 ° C.
Tg 60 ℃
Polyester resin (2-2): AV31 mgKOH / g, Mp121 ° C, Tg60 ° C
Polyester resin (2-3): AV5 mgKOH / g, Mp121 ° C, Tg60 ° C
Polyester resin (2-4): AV35 mgKOH / g, Mp121 ° C, Tg60 ° C

Each of the polyester resins (1-1) to (1-4) and (2-1) to (2-4) was synthesized by the following method. In the presence of a catalyst, the alcohol monomer and the carboxylic acid monomer were reacted under the conditions of a pressure of 0.40 MPa and a temperature of 230 ° C. for 2.5 hours. The amount of the catalyst added was 0.5% by mass with respect to the total mass of the alcohol monomer and the carboxylic acid monomer. Then, the pressure was returned to normal pressure over 1 hour, and the reaction was carried out for another 2 hours under the conditions of normal pressure and a temperature of 230 ° C. Tin 2-ethylhexanoate was used as the catalyst. As the carboxylic acid monomer, phthalic acid, trimellitic acid, and pyromellitic acid were used. As the alcohol monomer, an alkylene oxide adduct of bisphenol A, ethylene glycol, propylene glycol, and butanediol were used. The molar ratio of alcohol monomer to carboxylic acid monomer was 1: 2. Amount of phthalic acid, amount of trimellitic acid, amount of pyromellitic acid, amount of alkylene oxide adduct of bisphenol A, ethylene glycol added in the synthesis of each polyester resin so as to obtain a polyester resin having the above physical properties. , The amount of propylene glycol, and the amount of butanediol were adjusted.

<Manufacturing of toner A-1>
Toner A-1 was produced by the following method.

(Toner core forming process)
Using an FM mixer (“FM-10B” manufactured by Nippon Coke Industries Co., Ltd.), 50 parts by mass of polyester resin (1-1), 39 parts by mass of polyester resin (2-1), carbon black (“FM-10B” manufactured by Mitsubishi Chemical Co., Ltd.) MA100 ") 8 parts by mass, and ester wax (high-purity solid ester wax," Nissan Elector (registered trademark) WEP-5 "manufactured by Nichiyu Co., Ltd., component: pentaerythritol bechenic acid ester wax, melting temperature: 84 ° C.) 3 parts by mass were mixed to obtain a mixture. A twin-screw extruder (“TEM-26SS” manufactured by Toshiba Machine Co., Ltd.) was used to knead the mixture while melting it to obtain a kneaded product. Using a crusher (formerly Toa Kikai Seisakusho "Rotoplex (registered trademark) 16/8 type"), the kneaded product was first crushed until the diameter of the kneaded product was about 2 mm to obtain a primary crushed product. .. Using a crusher (“Turbo Mill RS type” manufactured by Freund Turbo Co., Ltd.), the primary crushed product was secondary crushed to obtain a secondary crushed product. A toner core was obtained by classifying the secondary pulverized product using a classifier (wind classifier using the Coanda effect: "Elbow Jet EJ-LABO type" manufactured by Nittetsu Mining Co., Ltd.). The volume median diameter of the obtained toner core was 7.0 μm.

(Shell layer forming process)
As a shell material, an oxazoline group-containing polymer aqueous solution (“Epocross (registered trademark) WS-300” manufactured by Nippon Catalyst Co., Ltd., monomer mass ratio: methyl methacrylate / 2-vinyl-2-oxazoline = 1/9, solid content concentration : 10% by mass, Tg: 90 ° C., oxazoline group content 7.7 mmol / g) was used. 100 parts by mass of a toner core and 6 parts by mass of an oxazoline group-containing polymer aqueous solution were added to the container of a mixer (“Uniaxial Free Mode Mixer FM-10” manufactured by Nikko Co., Ltd.). Purified water was added into the container so that the solid content concentration of the contents of the container was 50% by mass. The container contents were mixed until the median volume of the solid content of the container contents became about 7.0 μm to obtain a dispersion liquid. Next, purified water was added to the dispersion to adjust the solid content concentration of the dispersion to 20% by mass. While stirring the dispersion at a stirring speed of 240 rpm, the temperature of the dispersion was raised to 65 ° C. at a heating rate of 0.5 ° C./min. As the temperature was raised, the carboxyl group of the toner core contained in the dispersion and the oxazoline group of the shell material reacted. As a result, the oxazoline group was ring-opened and a shell layer was formed on the surface of the toner core. When the temperature of the dispersion reached 65 ° C., 14 parts by mass of an acetic acid aqueous solution having a concentration of 1% was added to the dispersion. Then, the temperature of the dispersion was lowered from 65 ° C. to 60 ° C. while stirring the dispersion at a stirring speed of 240 rpm. Then, the dispersion was held at 60 ° C. for 1 hour while stirring the dispersion at a stirring speed of 240 rpm. By holding at 60 ° C. for 1 hour, the unopened ring-opened oxazoline group in the shell layer reacted with the carboxyl group of acetic acid, and the oxazoline group was ring-opened. After holding at 60 ° C. for 1 hour, the dispersion was filtered to obtain a residue. The residue was washed with purified water, filtered, and dried to obtain toner particles. The volume median diameter of the toner particles was 7.0 μm.

(External process)
Using an FM mixer (“FM-10B” manufactured by Nippon Coke Industries Co., Ltd.), 100.0 parts by mass of toner particles obtained in the shell layer forming step, positively charged silica particles (“AEROSIL” manufactured by Nippon Aerosil Co., Ltd. (registered) Trademark) REA200 ”, average number of primary particle size: 13 nm) 1.5 parts by mass, titanium oxide particles (“MT-500B” manufactured by Teika Co., Ltd., untreated titanium oxide fine particles, average number of primary particle size: 35 nm) 1.5 parts by mass were mixed for 5 minutes under the condition of a rotation speed of 3500 rpm. As a result, the external additive particles were adhered to the surface of the toner particles to obtain toner A-1 (powder composed of a large number of toner particles to which the external additive was attached).

<Manufacturing of toners A-2 to A-7 and B-1 to B-6>
Toners A-2 to A-7 and B-1 to B-6 were prepared in the same manner as in the preparation of toner A-1, except that the following points were changed. Although the polyester resin (1-1) was used in the toner core forming step of the toner A-1, "Polyester 1" in Table 1 was used in each of the toner core forming steps of the toners A-2 to A-7 and B-1 to B-6. The polyester resin (any of polyester resins (1-1) to (1-4)) shown in the "Type" column of "" was used. Although polyester resin (2-1) was used in the toner core forming step of toner A-1, "polyester 2" in Table 1 was used in each of the toner core forming steps of toners A-2 to A-7 and B-1 to B-6. The polyester resin (any of polyester resins (2-1) to (2-4)) shown in the "Type" column of "" was used. In the shell layer forming step of the toner A-1, 6 parts by mass of an oxazoline group-containing polymer aqueous solution was added, but in the shell layer forming steps of the toners A-2 to A-7 and B-1 to B-6, the table is shown. The amount of the oxazoline group-containing polymer aqueous solution shown in the “Shell material” column of No. 1 was added. In the process of forming the shell layer of the toner A-1, 14 parts by mass of an acetic acid aqueous solution was added, but the shells of the toners A-2 to A-7, B-1 to B-3, and B-5 to B-6 were each added. In the layer forming step, an aqueous acetic acid solution in the amount shown in the column of "acetic acid" in Table 1 was added. In the production of the toner B-4, acetic acid could not be added in the shell layer forming step because aggregation occurred while the dispersion was heated in the shell layer forming step.

[Measuring method]
For each sample (each of toners A-1 to A-7, B-1 to B-3, and B-5 to B-6), the acid value of the toner core, the shell layer content, and the IR ratio (A / B) and were measured respectively. These measurement methods were as shown below. The results of these measurements are shown in Table 1. In toner B-4, aggregation occurred while the dispersion was heated in the shell layer forming step, and toner particles could not be formed. Therefore, the toner B-4 could not be produced, and the shell layer content and the IR ratio (A / B) of the toner B-4 could not be measured.

<Measurement method of acid value of toner core>
The acid value of the toner core was measured by a method conforming to JIS (Japanese Industrial Standards) K0070-1992.

<Measurement method of shell layer content>
The shell layer content was measured using Py-GC / MS. The Py-GC / MS includes a thermal decomposition device, a gas chromatograph device, and a mass spectrometer. The conditions of the pyrolysis apparatus were that the pyrolysis furnace temperature was 300 ° C. and the interface temperature was 200 ° C. The conditions of the gas chromatograph device are that the vaporization chamber temperature is 320 ° C., the column oven temperature is raised from 40 ° C. to 320 ° C. at a heating rate of 40 ° C./min, the carrier gas is He, and the purge flow rate. Was 3 mL / min, the injection mode was split, the split ratio was 50, and the measurement sample injection volume was 100 μg. The conditions of the mass spectrometer were that the ion source temperature was 220 ° C. and the interface temperature was 320 ° C.

First, a calibration curve was prepared. Specifically, 100 μg of the toner core and 10 μg of the shell material (WS-300 aqueous solution) having a predetermined concentration were mixed to prepare a sample for preparing a calibration curve. The predetermined concentration of the WS-300 aqueous solution was three kinds of concentration, the first concentration, the second concentration, and the third concentration. The first concentration was such that the content of the solid content of the shell material was 0.20% by mass with respect to the total of the mass of the toner core and the solid content of the shell material. The second concentration was such that the content of the solid content of the shell material was 0.40% by mass with respect to the total of the mass of the toner core and the solid content of the shell material. The third concentration was such that the content of the solid content of the shell material was 0.80% by mass with respect to the total of the mass of the toner core and the solid content of the shell material. The total of the mass of the toner core and the mass of the solid content of the shell material corresponds to the mass of the toner particles. The mass of the solid content of the shell material corresponds to the mass of the shell layer. The toner core used for preparing the concentration calibration curve was the toner core after the toner core forming step and before the shell layer forming step in the manufacturing of the toner A-1.

Using the above Py-GC / MS, a sample for preparing a calibration curve using the shell material having the first concentration was measured, and a chromatograph was obtained. The peak area of the peak of m / z 100 in the obtained chromatograph was calculated. The peak at m / z 100 was derived from methyl methacrylate (MMA), which is the main chain of the oxazoline group-containing aqueous polymer solution (Epocross (registered trademark) WS-300). For the calibration curve preparation sample using the second concentration shell material and the calibration curve preparation sample using the third concentration shell material, the measurement of the calibration curve preparation sample using the first concentration shell material is also performed. The peak area of the peak of m / z 100 in the chromatograph was calculated by the same method. Content of each calibration curve sample (specifically, the mass of the solid content of the shell material relative to the total mass of the toner core contained in the sample for preparing the calibration curve and the mass of the solid content of the shell material), And a calibration curve was prepared from the peak area. The obtained calibration curve is shown in FIG. The vertical axis in FIG. 5 represents the peak area of the peak of m / z 100. The horizontal axis in FIG. 5 is the content of the solid content of the shell material with respect to the total of the mass of the toner core and the mass of the solid content of the shell material (corresponding to the content of the shell layer with respect to the mass of the toner particles, unit: Mass%) is shown.

Next, the shell layer content of each of the toners A-1 to A-7, B-1 to B-3, and B-5 to B-6 was measured. The toner particles used for the measurement were used after the shell layer forming step and before the externalizing step in the production of each of the toners A-1 to A-7, B-1 to B-3, and B-5 to B-6. It was a toner particle. A measurement sample was measured using the above Py-GC / MS to obtain a chromatograph. The peak area of the peak of m / z 100 in the obtained chromatograph was calculated. The shell layer content of each toner was calculated from the peak area of the peak of m / z 100 using a calibration curve.

As a pyrolysis gas chromatograph mass spectrometer, a gas chromatograph mass spectrometer (“GCMS-QP2010 Ultra” manufactured by Shimadzu Corporation) was used. As a column, a GC column (“Agilent® J & W GC column Duraguard 122-5532G” manufactured by Agilent Technologies, Inc., inner diameter: 0.25 mm, film thickness: 0.25 μm, length: 30 m) was used.

<Measurement method of IR ratio (A / B)>
The IR ratio (A / B) was measured by the ATR method using FT-IR. Specifically, the measurement samples (toners A-1 to A-7, B-1) are measured by the ATR method using FT-IR (“FTS-60A / 896” manufactured by Agilent Technologies, Ltd.) under the following measurement conditions. ~ B-3 and B-5 to B-6) were measured to obtain an IR spectrum.

(IR measurement conditions)
Attachment: 1-reflection ATR attachment ("Silver Gate" manufactured by Specac)
Optical crystal: Ge
Incident angle: 45 °
Resolution: 4 cm ^-1
Accumulation number: 128 times

If sufficient sensitivity cannot be obtained, instead of the single-reflection ATR attachment ("Silver Gate" manufactured by Specac), the angle-variable single-reflection ATR ("VeeMax III with ATR" manufactured by ST Japan Co., Ltd.) Using "VeeMax"), the angle of incidence was changed from 45 ° to 65 °, and the measurement sample was measured.

From the obtained IR spectrum, ^{the absorbance of the peak of 1680 cm -1} and the absorbance of the peak of 1630 cm ^-1 were obtained. The absorbance of the peak at 1680 cm- ¹ is the absorbance (A) of the peak derived from the oxazoline group. The absorbance of the peak of 1630 cm- ¹ is the absorbance (B) of the peak derived from the amide bond formed by the reaction of the carboxyl group and the oxazoline group. From the obtained 1680 cm ^-1 peak absorbance (absorbance (A)) and 1630 cm ^-1 peak absorbance (absorbance (B)), according to the formula "IR ratio (A / B) = A / B". The IR ratio (A / B) was calculated.

[Evaluation methods]
The evaluation method of each sample (each of toners A-1 to A-7, B-1 to B-3, and B-5 to B-6) was as follows. The toner B-4 could not be evaluated because the toner particles could not be formed due to aggregation occurring while the dispersion was heated in the shell layer forming step.

<Charge retention>
The charge attenuation constant of the toner was measured by a method conforming to JIS (Japanese Industrial Standards) C 61340-2-1 using an electrostatic diffusion rate measuring device (“NS-D100” manufactured by Nanoseeds Co., Ltd.). Specifically, a sample (each of toners A-1 to A-7, B-1 to B-3, and B-5 to B-6) was placed in the measurement cell. The measuring cell was placed in the electrostatic diffusivity measuring device, and the sample was charged under the conditions shown below. The surface potential of the sample was continuously measured for 300 seconds after charging (measurement time below). From the surface potential measured during the decay time of 0 seconds or more and 2 seconds or less, the charge decay constant α (charge decay rate) was calculated according _{to the equation “V = V 0 exp (−α√t)”.} In the formula, V indicates the surface potential [unit: V], V ₀ indicates the initial surface potential [unit: V], and t indicates the decay time [unit: seconds]. From the charge attenuation constant α, the charge retention of the toner was evaluated based on the following criteria. The smaller the charge attenuation constant α, the slower the charge attenuation rate and the higher the charge retention of the toner.

(Measurement condition of charge attenuation constant)
Measurement environment: temperature 32.5 ° C, relative humidity 80% RH
Charging time: 0.5 seconds Charging polarity: Positive frequency: 10Hz
Measurement time: 300 seconds

(Evaluation criteria for charge retention)
Good: The charge attenuation constant is 0.020 or less.
Defective: The charge decay constant is over 0.020.

<Heat-resistant storage>
10 g of toner (evaluation target: each of toners A-1 to A-7, B-1 to B-3, and B-5 to B-6) was placed in a polyethylene container having a capacity of 20 mL, and the container was placed in 60. It was allowed to stand in an incubator set at ° C. for 1 hour. Then, the toner taken out from the incubator was cooled to 25 ° C. to obtain an evaluation toner.

Subsequently, the obtained evaluation toner was placed on a sieve having a known mass of 200 mesh (opening 75 μm). Then, the mass of the sieve containing the evaluation toner was measured, and the mass of the toner on the sieve (the mass of the toner before sieving) was determined. Subsequently, the above sieve is set in a powder property evaluation device (“Powder Tester (registered trademark)” manufactured by Hosokawa Micron Co., Ltd.), and the sieve is vibrated for 30 seconds under the condition of Leostud scale 5 according to the manual of the powder tester for evaluation. The toner was sieved. Then, after sieving, the mass of the sieving containing the toner was measured to determine the mass of the toner remaining on the sieving (the mass of the toner after sieving). From the mass of toner before sieving and the mass of toner after sieving, the formula "Toner passage rate = 100 x (mass of toner before sieving-mass of toner after sieving) / toner before sieving The toner passing rate (unit: mass%) was determined based on "mass". From the toner passage rate, the heat-resistant storage stability of the toner was evaluated based on the following criteria.

(Evaluation criteria for heat-resistant storage of toner)
Good: The toner passage rate is 80% by mass or more.
Defective: The toner passage rate is less than 80% by mass.

<Making a two-component developer>
Carrier ("Resin coated carrier" manufactured by Powder Tech Co., Ltd., carrier core: Cu-Zn ferrite core, coating resin: fluororesin, coating resin / carrier core mass ratio: 1/5, particle size: 35 μm, volume specific resistance value : 10 ⁷ Ω · cm, saturation magnetization: 70 emu / g) 90 parts by mass and toner (evaluation target: toners A-1 to A-7, B-1 to B-3, and B-5 to B-6 Each) 10 parts by mass was mixed for 30 minutes using a ball mill to obtain a two-component developer.

<Low temperature fixability>
An image was formed using the two-component developer obtained in the above <Preparation of two-component developer>, and the minimum fixing temperature of the toner was evaluated. As the evaluation machine, a modified machine of a printer (“FS-C5250DN” manufactured by Kyocera Document Solutions Co., Ltd., configuration of fixing device: Roller-Roller type heating and pressurizing fixing device, nip width of fixing device: 8 mm) was used. .. In the modified machine, the fixing device of the printer (FS-C5250DN) was modified so that the fixing temperature could be changed. A two-component developer was placed in the black developing device of the evaluation machine. In addition, replenishment toner was placed in the black toner container of the evaluation machine. As the replenishing toner, the same toner as the toner contained in the two-component developer was used. The replenishing toner was each of the toners A-1 to A-7, B-1 to B-3, and B-5 to B-6.

^{An unfixed solid on paper (A4 size plain paper, 90 g / m 2} ) under the condition of a toner loading amount of 1.0 mg / cm ² in an environment of a temperature of 23 ° C. and a humidity of 50% RH using an evaluation machine. An image (specifically, an unfixed toner image) was formed. Subsequently, the paper on which the image was formed was passed through the fixing device of the evaluation machine under the condition that the nip passing time was 40 msec. Then, the fixing temperature of the fixing device was raised by 5 ° C. from 100 ° C., and the minimum temperature (minimum fixing temperature) at which the unfixed solid image could be fixed on the paper was measured.

Whether or not the toner could be fixed in the measurement of the minimum fixing temperature was confirmed by the rubbing test shown below. The evaluation paper passed through the fixing device was bent so that the surface on which the image was formed was on the inside, and was rubbed 10 times back and forth on the crease using a 1 kg weight covered with a cloth. Subsequently, the paper was unfolded and the bent portion of the paper (the portion where the solid image was formed) was observed. Then, the peeling length (peeling length) of the toner at the bent portion was measured. The lowest fixing temperature among the fixing temperatures at which the peeling length was 1 mm or less was defined as the lowest fixing temperature (unit: ° C.). From the lowest fixing temperature, the low temperature fixability of the toner was evaluated based on the following criteria.

(Evaluation criteria for low temperature fixability of toner)
Good: The minimum fixing temperature is 150 ° C or less.
Defective: The minimum fixing temperature is over 150 ° C.

<Cleanability>
An image was formed using the two-component developer obtained in the above <Preparation of two-component developer>, and the cleanability of the toner was evaluated. As the evaluation machine, a color multifunction device (“TASKalfa 5550ci” manufactured by Kyocera Document Solutions Co., Ltd.) was used. A two-component developer was placed in the black developing device of the evaluation machine. In addition, replenishment toner was placed in the black toner container of the evaluation machine. As the replenishing toner, the same toner as the toner contained in the two-component developer was used. The replenishing toner was each of the toners A-1 to A-7, B-1 to B-3, and B-5 to B-6. The development conditions of the evaluation machine were set so that the amount of toner adhered to the photoconductor drum after development was 5 mg / cm ^2.

Using an evaluation machine, images having a printing rate of 5% were continuously formed on 2000 sheets of paper in an environment of a temperature of 23 ° C. and a humidity of 50% RH. After forming an image on 2000 sheets of paper, a blank image was formed on one sheet of paper in an environment of a temperature of 23 ° C. and a humidity of 50% RH using an evaluation machine. The obtained blank image was visually observed to confirm whether or not image noise was generated. Image noise is generated when toner drops and adheres to paper from the cleaning section of the evaluation machine. Furthermore, the fog density (FD) of the obtained blank image was measured. A fully automatic whiteness meter (“TC-6MC” manufactured by Tokyo Denshoku Co., Ltd.) was used to measure the FD of a blank image. The FD of the blank image was calculated based on the formula "FD = (reflection density of the blank image)-(reflection density of the unprinted paper)". The cleanability of the toner was evaluated from the FD of the blank image based on the following criteria.

(Evaluation criteria for toner cleanability)
Good: No image noise is generated due to toner dropping, and the FD is 0.01 or less.
Defective: Image noise is generated due to toner dropping, or the FD is more than 0.01. Alternatively, image noise is generated due to toner dropping, and the FD is more than 0.01.

[Evaluation results]
The results of evaluating the charge retention, heat storage property, low temperature fixability, and cleanability of each of the toners A-1 to A-7, B-1 to B-3, and B-5 to B-6 are shown. It is shown in Table 2. In Table 2, "NG" and "wt%" indicate "defective" and "mass%", respectively.

In the toners A-1 to A-7, the toner particles provided a toner core and a shell layer covering the surface of the toner core. The toner core contained a resin having a carboxyl group (specifically, a polyester resin).
The shell layer contained a resin containing a unit having an oxazoline group and a unit having an amide bond. The ratio of the absorbance of the peak derived from the oxazoline group (IR ratio (A / B)) to the absorbance of the peak derived from the amide bond measured by infrared spectroscopy is greater than 0.00 and 0.25 or less. (See Table 1). The content of the shell layer (shell layer content) with respect to the mass of the toner particles was 0.15% by mass or more and 0.40% by mass or less (see Table 1). Therefore, as shown in Table 2, each of the toners A-1 to A-7 was excellent in charge retention, heat-resistant storage, and low-temperature fixability. Further, each of the toners A-1 to A-7 was excellent in cleanability as shown in Table 2.

In toner B-1, the shell layer content was more than 0.40% by mass (see Table 1). Therefore, as shown in Table 2, the toner B-1 was inferior in low temperature fixability.

In toner B-2, the shell layer content was less than 0.15% by mass (see Table 1). Therefore, as shown in Table 2, the toner B-2 was inferior in heat-resistant storage stability.

In the toner B-3, the shell layer content was more than 0.40% by mass, and the IR ratio (A / B) was more than 0.25 (see Table 1). Therefore, as shown in Table 2, the toner B-3 was inferior in charge retention and low temperature fixability. Further, as shown in Table 2, the toner B-3 was also inferior in cleanability.

In toner B-4, aggregation occurred while the dispersion was heated in the shell layer forming step, and toner particles could not be formed. Therefore, the toner B-4 could not be produced, and the charge retention property, heat storage property, low temperature fixability, and cleanability of the toner B-4 could not be evaluated.

The IR ratio (A / B) of each of the toners B-5 and B-6 was more than 0.25 (see Table 1). Therefore, as shown in Table 2, the toners B-5 and B-6 were inferior in charge retention. Further, as shown in Table 2, the toners B-5 and B-6 were also inferior in cleanability.

From the above, it was shown that the toner according to the present invention including the toners A-1 to A-7 is excellent in charge retention, heat storage property, and low temperature fixability.

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

10: Toner particles 11: Toner core 12: Shell layer 21: First amide bond 22: Second amide bond 23: Oxazoline group 112: Shell material 113: Ring-opening agent 114: Shell resin

Claims (7)

Contains toner particles
The toner particles include a toner core and a shell layer that covers the surface of the toner core.
The toner core contains a binder resin having a carboxyl group, and the toner core contains a binder resin.
The shell layer contains a resin containing a unit having an oxazoline group and a unit having an amide bond.
The ratio of the absorbance of the peak with ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance of the peak with ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy is greater than 0.00 and 0. 25 or less,
The content of the shell layer to the mass of the toner particles is state, and are 0.15 wt% 0.40 wt% or less,
The shell layer is a toner that does not contain a basic substance. The toner according to claim 1, wherein the unit having an oxazoline group includes a unit represented by the formula (A).

(In the above formula (A), R ¹ represents a hydrogen atom or an alkyl group which may have a substituent.) The unit having an amide bond includes a unit having a first amide bond and a unit having a second amide bond.
The unit having the first amide bond includes a unit represented by the formula (B1).
The toner according to claim 2, wherein the unit having the second amide bond includes a unit represented by the formula (B2).

(Wherein (B1), R ¹ represents the same group as R ¹ in the formula (A), R ^B represents the atoms constituting the binder resin the toner core contains.)

(In the formula (B2), R ¹ represents the same group as ^{R 1} in the formula (A) ^{, and R 2} represents an alkyl group having 1 or more carbon atoms and 3 or less carbon atoms.) The toner according to claim 2 or 3, wherein the shell layer contains a polymer of a monomer containing a compound represented by the formula (1) and a (meth) acrylic acid alkyl ester.

(In the formula (1), R ¹ represents the same group as ^{R 1} in the formula (A).) Contains toner particles
The toner particles include a toner core and a shell layer that covers the surface of the toner core.
The toner core contains a binder resin having a carboxyl group, and the toner core contains a binder resin.
The shell layer contains a resin containing a unit having an oxazoline group and a unit having an amide bond.
The ratio of the absorbance of the peak with ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance of the peak with ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy is greater than 0.00 and 0. 25 or less,
The content of the shell layer with respect to the mass of the toner particles is 0.15% by mass or more and 0.40% by mass or less.
The binder resin contained in the toner core includes a first polyester resin and a second polyester resin.
The melting point of the first polyester resin is lower than the melting point of the second polyester resin.
When the acid value of the first polyester resin is greater than the acid value of the second polyester resin is equal to the acid value of the second polyester resin, Doo toner. A step of forming a shell layer covering the surface of the toner core by reacting the toner core, a shell material, and a ring-opening agent in an aqueous medium to obtain toner particles is included.
The shell material has an oxazoline group and
The toner core contains a binder resin having a carboxyl group, and the toner core contains a binder resin.
The ring-opening agent has a carboxyl group and has a carboxyl group.
The shell layer contains a resin containing the unit having an oxazoline group and the unit having an amide bond.
The ratio of the absorbance of the peak with ^{a wave number of 1680 cm -1} derived from the oxazoline group to the absorbance of the peak with ^{a wave number of 1630 cm -1} derived from the amide bond measured by infrared spectroscopy is greater than 0.00 and 0. 25 or less,
The amide bond includes a first amide bond and a second amide bond.
The first amide bond is formed by reacting the oxazoline group of the shell material with the carboxyl group of the binder resin contained in the toner core.
The second amide bond is formed by reacting the oxazoline group of the shell material with the carboxyl group of the ring-opening agent.
The content of the shell layer to the mass of the toner particles is state, and are 0.15 wt% 0.40 wt% or less,
A method for producing a toner, wherein the aqueous medium does not contain a dispersant and a basic substance. The method for producing a toner according to claim 6 , wherein the shell material further has a hydrophobic chain.

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