阅读说明：本技术 调色剂和双组分显影剂 (Toner and two-component developer ) 是由 桥本武 釜江健太郎 白山和久 井田隼人 松井崇 于 2019-06-12 设计创作，主要内容包括：本发明涉及调色剂和双组分显影剂。一种调色剂,其具有无机细颗粒和包含粘结剂树脂的调色剂颗粒,其中粘结剂树脂包含具有源自第一聚合性单体的第一单体单元和源自不同于第一聚合性单体的第二聚合性单体的第二单体单元的聚合物A,第一聚合性单体选自各自具有C<Sub>18-36</Sub>烷基的(甲基)丙烯酸酯,在聚合物A中第一单体单元的含量在特定范围内,第一单体单元的SP值和第二单体单元的SP值彼此具有特定关系,无机细颗粒用具有烷基的化合物来表面处理,并且无机细颗粒的体积电阻率在特定范围内。(The present invention relates to a toner and a two-component developer. A toner having inorganic fine particles and toner particles containing a binder resin, wherein the binder resin contains a polymer A having a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer different from the first polymerizable monomer, the first polymerizable monomer being selected from polymers each having C 18‑36 Alkyl (meth) acrylate, the content of the first monomer unit in the polymer A being in a specific rangeIn the above-mentioned method, the SP value of the first monomer unit and the SP value of the second monomer unit have a specific relationship with each other, the inorganic fine particles are surface-treated with a compound having an alkyl group, and the volume resistivity of the inorganic fine particles is in a specific range.)

1. A toner, comprising:

inorganic fine particles; and toner particles containing a binder resin, characterized in that,

the binder resin includes a polymer a containing a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer different from the first polymerizable monomer;

the first polymerizable monomer is selected from the group consisting of monomers each having C_18-36At least one monomer of the group consisting of alkyl (meth) acrylates;

the content of the first monomer unit in the polymer a is 5.0 to 60.0 mol% based on the total number of moles of all monomer units in the polymer a;

the content of the second monomer unit in the polymer a is 20.0 to 95.0 mol% of the total number of moles of all monomer units in the polymer a;

when the SP value of the first monomer unit is SP₁₁(J/cm³)^0.5And the SP value of the second monomer unit is SP₂₁(J/cm³)^0.5When the formula (1) and (2) are satisfied:

3.00≤(SP₂₁-SP₁₁)≤25.00...(1)

21.00≤SP₂₁...(2)；

the inorganic fine particles are surface-treated with a compound having an alkyl group; and

the volume resistivity of the inorganic fine particles is 1.0X 10⁵Omega cm to 1.0X 10¹³Ω·cm。

2. The toner according to claim 1, wherein a content of the second monomer unit in the polymer a is 40.0 mol% to 95.0 mol% of a total number of moles of all monomer units in the polymer a.

3. A toner, comprising:

inorganic fine particles; and toner particles containing a binder resin, characterized in that,

the binder resin includes a polymer a that is a polymer derived from a composition including a first polymerizable monomer and a second polymerizable monomer different from the first polymerizable monomer;

the first polymerizable monomer is selected from the group consisting of monomers each having C_18-36At least one monomer of the group consisting of alkyl (meth) acrylates;

the first polymerizable monomer is present in the composition in an amount of 5.0 to 60.0 mole% based on the total moles of all polymerizable monomers in the composition;

the second polymerizable monomer is present in the composition in an amount of 20.0 to 95.0 mole percent based on the total moles of all polymerizable monomers in the composition;

when the SP value of the first polymerizable monomer is SP₁₂(J/cm³)^0.5And the SP value of the second polymerizable monomer is SP₂₂(J/cm³)^0.5When the formula (3) and (4) are satisfied:

0.60≤(SP₂₂-SP₁₂)≤15.00...(3)

18.30≤SP₂₂...(4)；

the inorganic fine particles are surface-treated with a compound having an alkyl group; and

the volume resistivity of the inorganic fine particles is 1.0X 10⁵Omega cm to 1.0X 10¹³Ω·cm。

4. The toner according to claim 3, wherein a content of the second polymerizable monomer in the composition is 40.0 mol% to 95.0 mol% of a total number of moles of all polymerizable monomers in the composition.

5. The toner according to any one of claims 1 to 4, wherein the first polymerizable monomer is selected from the group consisting of monomers having C_18-36At least one monomer of the group consisting of (meth) acrylates of linear alkyl groups.

6. The toner according to any one of claims 1 to 4, wherein the second polymerizable monomer is at least one monomer selected from the group consisting of the following formulae (A) and (B):

in the formula (A), X represents a single bond or C_1-6Alkylene, and

R¹represents a nitrile group-C ≡ N;

amido-C (═ O) NHR¹⁰，R¹⁰Is a hydrogen atom or C_1-4An alkyl group;

a hydroxyl group;

-COOR¹¹，R¹¹is C_1-6Alkyl or C_1-6A hydroxyalkyl group;

carbamate-NHCOOR¹²，R¹²Is C_1-4An alkyl group;

ureido-NH-C (═ O) -N (R)¹³)₂Wherein R is¹³Each of which isIndependently is a hydrogen atom or C_1-6An alkyl group;

-COO(CH₂)₂NHCOOR¹⁴，R¹⁴is C_1-4An alkyl group; or

-COO(CH₂)₂-NH-C(＝O)-N(R¹⁵)₂Wherein R is¹⁵Each independently is a hydrogen atom or C_1-6Alkyl, and

R³is a hydrogen atom or a methyl group, and

in the formula (B), R²Is C_1-4Alkyl, and R³Is a hydrogen atom or a methyl group.

7. The toner according to any one of claims 1 to 4, wherein the second polymerizable monomer is at least one monomer selected from the group consisting of the following formulae (A) and (B):

in the formula (A), X represents a single bond or C_1-6Alkylene, and

R¹represents a nitrile group-C ≡ N;

amido-C (═ O) NHR¹⁰，R¹⁰Is a hydrogen atom or C_1-4An alkyl group;

a hydroxyl group;

-COOR¹¹，R¹¹is C_1-6Alkyl or C_1-6A hydroxyalkyl group;

ureido-NH-C (═ O) -N (R)¹³)₂Wherein R is¹³Each independently is a hydrogen atom or C_1-6An alkyl group;

-COO(CH₂)₂NHCOOR¹⁴，R¹⁴is C_1-4An alkyl group; or

-COO(CH₂)₂-NH-C(＝O)-N(R¹⁵)₂Wherein R is¹⁵Each independently is a hydrogen atom or C_1-6Alkyl, and

R³is a hydrogen atom or a methyl group, and

in the formula (B), R²Is C_1-4Alkyl, and R³Is a hydrogen atom or a methyl group.

8. The toner according to any one of claims 1 to 4, wherein the polymer A has a third monomer unit derived from a third polymerizable monomer which is different from the first polymerizable monomer and the second polymerizable monomer, and

the third polymerizable monomer is at least one monomer selected from the group consisting of styrene, methyl methacrylate, and methyl acrylate.

9. The toner according to any one of claims 1 to 4, wherein the content of the polymer A is 50% by mass or more based on the total mass of the binder resin.

10. The toner according to any one of claims 1 to 4, wherein a coverage of the toner particles by the inorganic fine particles is from 3 area% to 80 area%.

11. The toner according to any one of claims 1 to 4, wherein the compound having an alkyl group is selected from the group consisting of compounds having C_4-24At least one compound of the group consisting of alkyl compounds.

12. The toner according to any one of claims 1 to 4, wherein the compound having an alkyl group is at least one compound selected from the group consisting of a silane coupling agent, a fatty acid metal salt, and a silicone oil.

13. The toner according to any one of claims 1 to 4, wherein the inorganic fine particles are strontium titanate.

14. The toner according to any one of claims 1 to 4, wherein the inorganic fine particles are strontium titanate having a perovskite-type crystal structure.

15. The toner according to any one of claims 1 to 4, wherein the toner has a charge decay rate coefficient of 3 to 100 measured in an environment of 80% RH at 30 ℃.

16. The toner according to any one of claims 1 to 4, wherein the inorganic fine particles have a dielectric constant at 1MHz of 20pF/m to 100 pF/m.

17. The toner according to any one of claims 1 to 4, wherein the carbon number of the alkyl group of the first polymerizable monomer is assumed to be C_xAnd the carbon number of the alkyl group of the compound having an alkyl group is C_yThen C is_x/C_yIs 0.8 to 24.0.

18. The toner according to any one of claims 1 to 4, wherein the polymer A is a vinyl polymer.

19. A two-component developer comprising a toner and a magnetic carrier, characterized in that the toner is the toner according to any one of claims 1 to 18.

Technical Field

The present invention relates to a toner for use in electrophotographic systems, electrostatic recording systems, electrostatic printing systems, and toner ejection systems, and a two-component developer using the toner.

Background

In recent years, as electrophotographic full-color copying machines have proliferated, demands for higher printer speeds and more energy saving have been increasing. In order to realize high-speed printing, a technique of melting toner more quickly in a fixing step has been studied. In order to improve productivity, a technique of shortening various control times during one job or between jobs has also been studied. As an energy-saving measure, in order to reduce energy consumption in the fixing step, a technique of fixing a toner at a lower temperature has been studied.

Methods of achieving high-speed printing while improving the low-temperature fixability of toner include reducing the glass transition point or softening point of a binder resin in toner, and using a binder resin having a rapid melting property. In recent years, various toners containing a crystalline polyester as a resin having a rapid melting property have been proposed. However, crystalline polyesters have a problem of charging stability under a high-temperature and high-humidity environment, and particularly have a problem of retaining charging performance after standing under a high-temperature and high-humidity environment.

Various toners using a crystalline vinyl resin as other crystalline resin having a rapid melting property have been proposed.

For example, japanese patent application laid-open No. 2014-130243 proposes a toner that achieves both low-temperature fixability and heat-resistant storage stability by using an acrylate resin having crystallinity in a side chain.

Japanese patent application publication No. 2017-58604 proposes a toner using a binder resin containing an amorphous vinyl resin chemically linked to a crystalline vinyl resin.

The toners in these patent documents can provide both low-temperature fixability and heat-resistant storage stability, as well as a certain degree of improvement in charging stability as a weak point of toners using crystalline polyester resins. However, it has been found that these toners using a crystalline vinyl resin as a binder resin have a slow rise in charging.

Therefore, it has been found that when an image having a small print rate is printed immediately after an image having a large print rate is printed, the image density gradually changes due to the difference between the charge amounts of the toner present in the developing device and the new toner supplied into the developing device. This tendency is particularly remarkable in a low humidity environment.

Disclosure of Invention

The present invention provides a toner that solves these problems. Specifically, the present invention provides a toner that achieves both low-temperature fixability and heat-resistant storage stability, has charging stability even in a high-temperature and high-humidity environment, has a rapid rise in charging, and hardly causes a change in density regardless of the image print ratio.

A first embodiment of the present invention is a toner including:

inorganic fine particles; and toner particles containing a binder resin, wherein

The binder resin includes a polymer a containing a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer, and the second polymerizable monomer is different from the first polymerizable monomer;

the first polymerizable monomer is selected from the group consisting of_18-36At least one monomer of the group consisting of alkyl (meth) acrylates;

the content of the first monomer unit in the polymer a is 5.0 to 60.0 mol% based on the total number of moles of all monomer units in the polymer a;

the content of the second monomer unit in the polymer a is 20.0 to 95.0 mol% based on the total number of moles of all the monomer units in the polymer a;

when the SP value of the first monomer unit is SP₁₁(J/cm³)^0.5And the SP value of the second monomer unit is SP₂₁(J/cm³)^0.5When the formula (1) and (2) are satisfied:

3.00≤(SP₂₁-SP₁₁)≤25.00...(1)

21.00≤SP₂₁...(2)；

the inorganic fine particles are surface-treated with a compound having an alkyl group; and

the volume resistivity of the inorganic fine particles was 1.0X 10⁵Omega cm to 1.0X 10¹³Ω·cm。

The second embodiment of the present invention is a toner having inorganic fine particles and toner particles containing a binder resin, wherein

The binder resin includes a polymer a that is a polymer derived from a composition containing a first polymerizable monomer and a second polymerizable monomer different from the first polymerizable monomer;

the first polymerizable monomer is selected from the group consisting of_18-36At least one monomer of the group consisting of alkyl (meth) acrylates;

the first polymerizable monomer is present in the composition in an amount of 5.0 to 60.0 mole% based on the total moles of all polymerizable monomers in the composition;

the second polymerizable monomer is present in the composition in an amount of 20.0 to 95.0 mole percent based on the total moles of all polymerizable monomers in the composition;

when the SP value of the first polymerizable monomer is SP₁₂(J/cm³)^0.5And the SP value of the second polymerizable monomer is SP₂₂(J/cm³)^0.5When the formula (3) and (4) are satisfied:

0.60≤(SP₂₂-SP₁₂)≤15.00...(3)

18.30≤SP₂₂...(4)；

the inorganic fine particles are surface-treated with a compound having an alkyl group; and

the volume resistivity of the inorganic fine particles was 1.0X 10⁵Omega cm to 1.0X 10¹³Ω·cm。

The toner of the present invention realizes both low-temperature fixability and heat-resistant storage stability, has charging stability even in a high-temperature and high-humidity environment, has a rapid rise in charging, and hardly causes density variations regardless of the image printing rate.

Further features of the present invention will become apparent from the following description of exemplary embodiments.

Detailed Description

Unless otherwise indicated, the recitation of numerical ranges in this disclosure, such as "X to Y" or "X to Y," includes numbers at the upper and lower limits of the ranges.

In the present invention, (meth) acrylate means acrylate and/or methacrylate.

In the present invention, "monomer unit" refers to a reaction form of monomer substances in a polymer, and one carbon-carbon bonding segment (section) in a main chain composed of a polymerized vinyl monomer in the polymer is considered as one unit.

The vinyl monomer may be represented by the following formula (Z):

[ in the formula (Z), Z₁Represents a hydrogen atom or an alkyl group (preferably C)_1-3Alkyl, or more preferably methyl), Z₂Represents an optional substituent]。

The crystalline resin is a resin showing a clear endothermic peak in Differential Scanning Calorimetry (DSC).

The first embodiment of the present invention is a toner having inorganic fine particles and toner particles containing a binder resin, wherein

The binder resin includes a polymer a having a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer, and the second polymerizable monomer is different from the first polymerizable monomer;

the first polymerizable monomer is selected from the group consisting of_18-36At least one monomer of the group consisting of alkyl (meth) acrylates;

the content of the first monomer unit in the polymer a is 5.0 to 60.0 mol% based on the total number of moles of all monomer units in the polymer a;

the content of the second monomer unit in the polymer a is 20.0 to 95.0 mol% based on the total moles of all the monomer units in the polymer a; and

assuming that the SP value of the first monomer unit is taken as SP₁₁(J/cm³)^0.5And the SP value of the second monomer unit is taken as SP₂₁(J/cm³)^0.5Then, the formulas (1) and (2) are satisfied:

3.00≤(SP₂₁-SP₁₁)≤25.00...(1)

21.00≤SP₂₁...(2)；

the inorganic fine particles are surface-treated with a compound having an alkyl group; and

the volume resistivity of the inorganic fine particles was 1.0X 10⁵Omega cm to 1.0X 10¹³Ω·cm。

The second embodiment of the present invention is a toner including inorganic fine particles; and toner particles containing a binder resin, wherein

The binder resin includes a polymer a that is a polymer derived from a composition containing a first polymerizable monomer and a second polymerizable monomer different from the first polymerizable monomer;

the first polymerizable monomer is selected from the group consisting of_18-36At least one monomer of the group consisting of alkyl (meth) acrylates;

the first polymerizable monomer is present in the composition in an amount of 5.0 to 60.0 mole% based on the total moles of all polymerizable monomers in the composition;

the second polymerizable monomer is present in the composition in an amount of 20.0 to 95.0 mole percent based on the total moles of all polymerizable monomers in the composition;

assuming that the SP value of the first polymerizable monomer is SP₁₂(J/cm³)^0.5And the SP value of the second polymerizable monomer is taken as SP₂₂(J/cm³)^0.5Then, the formulas (3) and (4) are satisfied:

0.60≤(SP₂₂-SP₁₂)≤15.00...(3)

18.30≤SP₂₂...(4)；

the inorganic fine particles are surface-treated with a compound having an alkyl group; and

the volume resistivity of the inorganic fine particles was 1.0X 10⁵Omega cm to 1.0X 10¹³Ω·cm

The present inventors consider the mechanism of the effect of the present invention to be as follows.

It is considered that the charge rising speed of the toner is determined by the speed at which the charge migrates from the inorganic fine particles on the toner particle surface to the toner particle surface and is saturated in the entire toner particles. Generally, low-resistivity inorganic fine particles such as titanium oxide have been used to increase the speed of charge transfer from the inside of the inorganic fine particles, thereby increasing the charge rising speed of the toner.

However, the studies of the present inventors have revealed that when a crystalline vinyl resin is used as the binder resin, this does not by itself sufficiently increase the charge rising speed. It is considered that the reason is because the transfer of charge from the inorganic fine particles to the toner particle surface is restricted.

As a result of studies on changing the composition of the binder resin, the present inventors found that the charge rise can be slightly improved by including a monomer unit having a high SP value in the crystalline vinyl resin. It is believed that when the SP value is high, charge transfer is faster due to the presence of electric dipoles resulting from charge localization (localization). However, low-temperature fixability and heat-resistant storage stability may decrease depending on the composition.

As a result of intensive studies, the present inventors have found that these problems can be solved by controlling the molar ratio, SP value and SP value difference of monomer units derived from a plurality of polymerizable monomers in a binder resin of a toner, and the resistivity and surface treatment of inorganic fine particles on the surface of toner particles, and then have arrived at the present invention.

The binder resin comprises a polymer A having a first monomer unit derived from a first polymerizable monomer selected from the group consisting of monomers each having C_18-36At least one monomer from the group consisting of alkyl (meth) acrylates.

If the first monomer unit is of C_18-36Alkyl (meth) acrylates, toThe binder resin has crystallinity and is improved in low-temperature fixability.

In the first embodiment, the content of the first monomer unit in the polymer a is 5.0 to 60.0 mol% based on the total number of moles of all monomer units in the polymer a.

In a second embodiment, the polymer a is a polymer derived from a composition containing a first polymerizable monomer and a second polymerizable monomer different from the first polymerizable monomer. The first polymerizable monomer is contained in the composition in an amount of 5.0 to 60.0 mol% based on the total number of moles of all polymerizable monomers in the composition.

The content within this range produces good low-temperature fixability and good rise in charging in a low-humidity environment. If the content is less than 5.0 mol%, the low-temperature fixability is lowered. On the other hand, if the content exceeds 60.0 mol%, since more polymer is occupied by the non-polar moiety having a low SP value, the rise of charge in a low humidity environment is reduced. The content is more preferably 10.0 mol% to 60.0 mol%, or still more preferably 20.0 mol% to 40.0 mol%.

The first polymerizable monomer forming the first monomer unit is selected from the group consisting of monomers having C_18-36At least one monomer from the group consisting of alkyl (meth) acrylates.

Each having C_18-36Examples of the (meth) acrylate of the alkyl group include those each having C_18-36Linear alkyl (meth) acrylates such as stearyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, heneicosyl (meth) acrylate, behenyl (meth) acrylate, ditetradecyl (meth) acrylate, hexacosyl (meth) acrylate, dioctadecyl (meth) acrylate, triacontyl (meth) acrylate, and triacontyl (meth) acrylate]And each has C_18-36Branched alkyl (meth) acrylates [ (2-decyltetradecyl (meth) acrylate) and the like]。

Among them, from the viewpoint of storage stability of the toner, it is preferable to select from the group consisting of those having C each_18-36(meth) acrylic acid esters of straight-chain alkyl radicalsAt least one monomer from the group consisting of alkenoic acid esters. More preferably selected from the group consisting of_18-30At least one monomer of the group consisting of linear alkyl (meth) acrylates, and still more preferably at least one monomer selected from the group consisting of linear stearyl (meth) acrylate and behenyl (meth) acrylate.

As the first polymerizable monomer, one kind of monomer alone or a combination of two or more kinds may be used.

In the first embodiment, the polymer a has a second monomer unit derived from a second polymerizable monomer different from the first polymerizable monomer. Assuming that the SP value of the second monomer unit is SP₂₁Then, the following formula (2) is satisfied. It is more preferable to satisfy the following formula (2)', and it is still more preferable to satisfy the following formula (2) ".

21.00≤SP₂₁...(2)

21.00≤SP₂₁≤40.00...(2)'

25.00≤SP₂₁≤30.00...(2)”

In the second embodiment, the SP value of the second polymerizable monomer is assumed to be SP₂₂(J/cm³)^0.5Then, the following formula (4) is satisfied. It is more preferable to satisfy the following formula (4)', and it is still more preferable to satisfy the following formula (4) ".

18.30≤SP₂₂...(4)

18.30≤SP₂₂≤30.00...(4)'

21.00≤SP₂₂≤23.00...(4)”

If the SP value of the second monomer unit or the second polymerizable monomer is within this range, charge transfer from the low-resistivity inorganic fine particles is rapid, and the charge rising speed increases.

Here, the SP value is an abbreviation of "solubility parameter" and is a value indicating solubility. The calculation method is as follows.

In the first embodiment, it is assumed that the SP value of the first monomer unit is taken as SP₁₁(J/cm³)^0.5And the SP value of the second monomer unit is taken as SP₂₁(J/cm³)^0.5Then, the following formula (1) is satisfied. Preferably satisfies the following formula (1) ', more preferably satisfies the formula (1)', (1) ", and still more preferably satisfies the formula (1)"'.

In the second embodiment, the SP value of the first polymerizable monomer is assumed to be SP₁₂(J/cm³)^0.5And the SP value of the second polymerizable monomer is taken as SP₂₂(J/cm³)^0.5Then, the following formula (3) is satisfied. Preferably, formula (3) ', more preferably formula (3) ", and still more preferably formula (3)"'.

3.00≤(SP₂₁-SP₁₁)≤25.00...(1)

3.00≤(SP₂₁-SP₁₁)≤20.00...(1)'

4.00≤(SP₂₁-SP₁₁)≤15.00...(1)”

5.00≤(SP₂₁-SP₁₁)≤15.00...(1)”'

0.60≤(SP₂₂-SP₁₂)≤15.00...(3)

0.60≤(SP₂₂-SP₁₂)≤10.00...(3)'

2.00≤(SP₂₂-SP₁₂)≤7.00...(3)”

3.00≤(SP₂₂-SP₁₂)≤7.00...(3)”'

The SP value in the present invention is expressed as (J/cm)³)^0.5Is given in (1), but formula 1 (cal/cm) can be used³)^0.5＝2.045×10³(J/m³)^0.5Converting them into (cal/cm)³)^0.5The unit of (c).

If the above SP value difference is satisfied, the crystallinity of the polymer A is not lowered and the melting point can be maintained. Thus, both low-temperature fixability and heat-resistant storage stability can be achieved.

The charge rise is also good because of the interaction between the first monomer unit and the alkyl group of the low-resistance inorganic fine particles, and the increased possibility of charge transfer from the low-resistance inorganic fine particles to the polar portion of the second monomer unit.

The mechanism thereof is considered as follows.

When the first monomer unit is introduced into the polymer a and the first monomer units are aggregated together, crystallinity is exhibited, but when other monomer units are introduced, they generally inhibit crystallization, making it more difficult for the polymer to exhibit crystallinity. This tendency is particularly pronounced when the first monomer unit and the other monomer units in a single molecule of the polymer are randomly bonded.

However, in the present invention, it is considered that SP is used for the polymer₂₂-SP₁₂The polymerizable monomer within the range of the above formula (3) constitutes, and therefore the first polymerizable monomer and the second polymerizable monomer may be continuously bonded to some extent during polymerization, rather than being randomly bonded. This means that the first monomer unit can be aggregated together in the polymer a, and therefore even if other monomer units are introduced, crystallinity can be improved and the melting point can be maintained.

Further, it is considered that if SP₂₁-SP₁₁Within the range of the above formula (1), then in the polymer a, the first monomer unit and the second monomer unit may form a clear phase-separated state instead of being mixed together, and thus crystallinity is not lowered and the melting point is maintained.

The polymer a preferably has a crystalline segment containing a first monomer unit derived from a first polymerizable monomer. The polymer a also preferably has an amorphous segment containing a second monomer unit derived from a second polymerizable monomer.

It is also considered that since the first monomer units are continuously connected, it is easier to interact with the alkyl groups of the low-resistivity inorganic fine particles, so that the adhesion between the inorganic fine particles and the toner particles is improved. Similarly, it is considered that since the second monomer units are continuously connected, it is more likely to exhibit a configuration that facilitates rapid charge transfer from the low-resistivity inorganic fine particles to the high SP value second monomer units, so that the charge rise is improved.

In the first embodiment, the content of the second monomer unit in the polymer a is 20.0 mol% to 95.0 mol% of the total number of moles of all the monomer units in the polymer a.

In addition, in the second embodiment, the content of the second polymerizable monomer in the composition is 20.0 mol% to 95.0 mol% of the total number of moles of all polymerizable monomers in the composition.

If these contents are within these ranges, charge transfer from the low-resistance inorganic fine particles to the polar portion of the second monomer unit may be fast. The content is preferably 40.0 mol% to 95.0 mol%, or more preferably 40.0 mol% to 70.0 mol%, from the viewpoint of charge rise in a low-humidity environment.

Among them, in the following examples, a polymerizable monomer satisfying formula (1) or (3) may be used as the second polymerizable monomer for forming the second monomer unit. As the second polymerizable monomer, one kind of monomer alone or a combination of two or more kinds may be used.

Monomer having nitrile group: for example, acrylonitrile and methacrylonitrile, and the like.

Monomer having hydroxyl group: for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and the like.

Monomers having an amido group: for example, acrylamide and by reacting C by known methods_1-30Amine with C having ethylenic unsaturation_2-30A monomer obtained by reacting a carboxylic acid (acrylic acid, methacrylic acid, etc.).

Monomer having a urethane group: for example, by reacting C having an ethylenically unsaturated bond by means of a known method_2-22Alcohols (2-hydroxyethyl methacrylate, vinyl alcohol, etc.) with C_1-30Isocyanates [ monoisocyanate compounds (phenylsulfonyl isocyanate, tolylsulfonyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, butyl isocyanate, hexyl isocyanate, t-butyl isocyanate, cyclohexyl isocyanate, octyl isocyanate, 2-ethylhexyl isocyanate, dodecyl isocyanate, adamantyl isocyanate, 2, 6-dimethylphenyl isocyanate, 3, 5-dimethylphenyl isocyanate, 2, 6-dipropylphenyl isocyanate and the like ], aliphatic diisocyanate compounds (trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 1, 3-butylene diisocyanate, dodecamethylene diisocyanate and 2,4, 4-trimethylhexamethylene diisocyanate, etc.), alicyclic diisocyanateEster compounds (1, 3-cyclopentene diisocyanate, 1, 3-cyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, and the like) and aromatic diisocyanate compounds (phenylene diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 2 '-diphenylmethane diisocyanate, 4' -toluidine diisocyanate, 4 '-diphenyl ether diisocyanate, 4' -diphenyl diisocyanate, 1, 5-naphthalene diisocyanate, and xylylene diisocyanate, and the like).]The resulting monomer is reacted.

By subjecting C to_1-26Alcohols (methanol, ethanol, propanol, isopropanol, butanol, t-butanol, pentanol, heptanol, octanol, 2-ethylhexanol, nonanol, decanol, undecanol, lauryl alcohol, dodecanol, myristyl alcohol, pentadecanol, hexadecanol, heptadecanol, stearyl alcohol, isostearyl alcohol, trans-oleyl alcohol, linoleyl alcohol, linolenyl alcohol, nonadecanol, heneicosanol, behenyl alcohol, erucyl alcohol (erucyl alcohol), etc.) and C having an ethylenically unsaturated bond_2-30Isocyanate [ (meth) acrylic acid 2-isocyanatoethyl ester and (meth) acrylic acid 2- (0- [1' -methylpropylideneamino)]Carboxyamino) ethyl ester, 2- [ (3, 5-dimethylpyrazolyl) carbonylamino (meth) acrylate]Ethyl ester and 1,1- (bis (meth) acryloyloxymethyl) ethyl isocyanate and the like]And the like.

Monomers having urea groups: for example, by subjecting C to_3-22Amines [ primary amines (n-butylamine, t-butylamine, propylamine, isopropylamine, etc.), secondary amines (di-n-ethylamine, di-n-propylamine, di-n-butylamine, etc.), anilines, cyclohexylamine, etc]With C having ethylenic unsaturation_2-30Isocyanate, and the like.

Monomer having carboxyl group: for example, methacrylic acid, acrylic acid, 2-carboxyethyl (meth) acrylate.

Among them, it is desirable to use a monomer having a nitrile group, an amide group, a urethane group, a hydroxyl group or a urea group. More preferred are monomers having an ethylenically unsaturated bond and at least one functional group selected from the group consisting of a nitrile group, an amide group, a urethane group, a hydroxyl group and a urea group. These monomers are desirable in order to further improve the charge rise in a low humidity environment. Among them, the nitrile group has a strong electron withdrawing property, and is particularly desirable for accelerating charge transfer.

Vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, and vinyl caprylate can also be preferably used as the second polymerizable monomer.

Since the vinyl ester is a non-conjugated monomer and can easily maintain an appropriate degree of reactivity with the first polymerizable monomer, it is easier to improve the crystallinity of the polymer a and achieve both low-temperature fixability and heat-resistant storage stability.

The second polymerizable monomer preferably has an ethylenically unsaturated bond, and more preferably has one ethylenically unsaturated bond.

Further, the second polymerizable monomer is preferably at least one monomer selected from the group consisting of the following formulae (a) and (B):

(wherein X represents a single bond or C_1-6Alkylene, and

R¹represents a nitrile group (-C ≡ N);

amido (-C (═ O) NHR¹⁰(R¹⁰Is a hydrogen atom or C_1-4Alkyl));

a hydroxyl group;

-COOR¹¹(R¹¹is C_1-6(preferably C)_1-4) Alkyl or C_1-6(preferably C)_1-4) Hydroxyalkyl radicals);

carbamate group (-NHCOOR)¹²(R¹²Is C_1-4Alkyl));

ureido (-NH-C (═ O) -N (R)¹³)₂(wherein R is¹³Each independently is a hydrogen atom or C_1-6(preferably C)_1-4) Alkyl));

-COO(CH₂)₂NHCOOR¹⁴(R¹⁴is C_1-4Alkyl groups); or

-COO(CH₂)₂-NH-C(＝O)-N(R¹⁵)₂(wherein R is¹⁵Each independently is a hydrogen atom or C_1-6(preferably C)_1-4) Alkyl groups).

Preferably, R¹Represents a nitrile group (-C ≡ N);

amido (-C (═ O) NHR¹⁰(R¹⁰Is a hydrogen atom or C_1-4Alkyl));

a hydroxyl group;

-COOR¹¹(R¹¹is C_1-6(preferably C)_1-4) Alkyl or C_1-6(preferably C)_1-4) Hydroxyalkyl radicals);

ureido (-NH-C (═ O) -N (R)¹³)₂(wherein R is¹³Each independently is a hydrogen atom or C_1-6(preferably C)_1-4) Alkyl));

-COO(CH₂)₂NHCOOR¹⁴(R¹⁴is C_1-4Alkyl groups); or

-COO(CH₂)₂-NH-C(＝O)-N(R¹⁵)₂(wherein R is¹⁵Each independently is a hydrogen atom or C_1-6(preferably C)_1-4) Alkyl groups).

R²Is C_1-4Alkyl, and R³Each independently is a hydrogen atom or a methyl group. )

One kind of the second polymerizable monomer may be used alone, or two or more kinds may be used in combination.

In the present invention, SP in the formula (1) when a plurality of monomer units satisfying the condition of the first monomer unit are present in the polymer A₁₁Is the weighted average of the respective SP values in these monomer units. For example, if the polymer contains S in an amount of A mol% of the total number of moles of all monomer units satisfying the condition of the first monomer unitP value is SP₁₁₁And an SP value of an amount of (100-A) mol% of the total number of moles of all monomer units satisfying the condition of the first monomer unit is SP₁₁₂Monomer unit B of (1), then the SP value (SP)₁₁) The following steps are changed:

SP₁₁＝(SP₁₁₁×A+SP₁₁₂×(100-A))/100。

when three or more monomer units satisfying the condition of the first monomer unit are included, the calculation is similar. Similarly, SP₁₂Also, the average value calculated based on the molar ratio of each first polymerizable monomer is shown.

Further, the second monomer unit in the present invention corresponds to a monomer having a SP calculated by the above method₁₁Value-combined SP satisfying formula (1)₂₁All monomer units of value. Similarly, the second polymerizable monomer corresponds to a monomer having an SP calculated by the above method₁₂Value-combined SP satisfying formula (3)₂₂All polymerizable monomers of value.

That is, when the second polymerizable monomer is two or more polymerizable monomers, SP₂₁Represents the SP value of the monomer unit derived from each polymerizable monomer, and determines the SP of the monomer unit derived from each second polymerizable monomer₂₁-SP₁₁. Similarly, SP₂₂Represents the SP value of each polymerizable monomer, and determines the SP of each second polymerizable monomer₂₂-SP₁₂。

The polymer a is preferably a vinyl polymer. The vinyl polymer may be, for example, a polymer of a monomer having an ethylenically unsaturated bond. The ethylenically unsaturated bond is a radical polymerizable carbon-carbon double bond, and examples include vinyl group, propenyl group, acryloyl group, methacryloyl group and the like.

The acid value Av of the polymer A is preferably 30.0mg KOH/g or less, or more preferably 20.0mg KOH/g or less. There is no particular lower limit, but 0mg KOH/g or more is preferable. If the acid value is 30.0mg KOH/g or less, crystallization of the polymer A is not easily inhibited and the melting point is kept good.

The weight average molecular weight (Mw) of the Tetrahydrofuran (THF) -soluble component of polymer a, as measured by Gel Permeation Chromatography (GPC), is preferably 10,000 to 200,000, or more preferably 20,000 to 150,000. If the weight average molecular weight (Mw) is within this range, it becomes easier to maintain elasticity around room temperature.

The melting point of polymer a is preferably 50 ℃ to 80 ℃, or more preferably 53 ℃ to 70 ℃. When the melting point is 50 ℃ or higher, the heat-resistant storage stability is good, and when the melting point is 80 ℃ or lower, the low-temperature fixing property is improved.

The polymer a may also contain a third monomer unit derived from a third polymerizable monomer outside the ranges of formulae (1) and (3) (i.e., different from the first polymerizable monomer and the second polymerizable monomer), as long as the above-described molar ratio of the first monomer unit derived from the first polymerizable monomer and the second monomer unit derived from the second polymerizable monomer is maintained.

Among the monomers mentioned as examples of the second polymerizable monomer, those which do not satisfy the above formula (1) or formula (3) may be used as the third polymerizable monomer.

The following monomers having no nitrile, amide, urethane, hydroxyl, urea or carboxyl groups may also be used: styrene and its derivatives such as styrene and o-methylstyrene, and (meth) acrylic acid esters such as methyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate.

The third polymerizable monomer is preferably at least one monomer selected from the group consisting of styrene, methyl methacrylate, and methyl acrylate.

When these monomers satisfy the formula (1) or the formula (3), they can be used as the second polymerizable monomer.

In order to more easily obtain the effects of the present invention, the content of the polymer a is preferably 50% by mass or more of the total mass of the binder resin. More preferably, it is 80 to 100% by mass, and still more preferably, the binder resin is polymer a.

In order to more easily obtain the effects of the present invention, it is also desirable that the polymer a be present on the surface of the toner particles.

The binder resin may further contain a resin other than the polymer a as necessary for the purpose of improving pigment dispersibility and the like.

The following resins are examples of resins other than polymer a that can be used for the binder resin: homopolymers of styrene and substituted styrene such as poly (p-chlorostyrene) and poly (vinyltoluene); styrene copolymers such as styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene- α -chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, and styrene-acrylonitrile-indene copolymer; and polyvinyl chloride, phenol resins, natural resin-modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyester resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, and petroleum-based resins.

Among them, styrene copolymer or polyester resin is preferable. The resin is also preferably non-crystalline.

The toner of the present invention is characterized by containing a resin having a volume resistivity of 1.0X 10⁵Omega cm to 1.0X 10¹³Omega cm inorganic fine particles.

If the volume resistivity of the inorganic fine particles is within this range, the charge transfer within the inorganic fine particles occurs more rapidly, and the charge rise is improved. If the volume resistivity is less than 1.0X 10⁵Ω · cm is too low in resistivity, and thus the charging performance is lowered in a high-temperature and high-humidity environment. On the other hand, if it exceeds 1.0X 10¹³Ω · cm, the charge rises slowly due to high resistance. The volume resistivity of the inorganic fine particles is preferably 1.0X 10⁸Omega cm to 7.0X 10¹²Omega cm. The volume resistivity can be controlled by controlling the kind of the inorganic fine particles, the kind of the surface treatment, the concentration of the surface treatment agent, and the like.

Volume resistivity value of 1.0X 10⁵Omega cm to 1.0X 10¹³Examples of the inorganic fine particles of Ω · cm include metal titanates such as strontium titanate, calcium titanate, and magnesium titanate, and metal oxides such as titanium oxide, magnesium oxide, zinc oxide, and cerium oxide.

Among them, titanium oxide, strontium titanate, calcium titanate, or zinc oxide is preferable, and strontium titanate is more preferable. For these, properties such as particle diameter, resistivity, and dielectric constant can be controlled relatively easily by controlling the manufacturing conditions. The strontium titanate preferably has a perovskite-type crystal structure. If the strontium titanate has a perovskite-type crystal structure, the charge transfer of the second monomer unit is accelerated.

The fine particles of strontium titanate, calcium titanate and magnesium titanate can be obtained by, for example, an atmospheric pressure heating reaction method. In this case, an inorganic acid peptized product of a hydrolyzed titanium compound is used as a titanium oxide source, and a water-soluble acidic metal compound is used as a metal oxide source. The production can be carried out by adding an alkaline aqueous solution of 60 ℃ or higher and reacting the mixture, and then treating the mixture with an acid.

The method for producing the titanium oxide fine particles is not particularly limited, and examples include titanium oxide particles produced by a conventional sulfuric acid method and chlorine method, and titanium oxide particles produced by a vapor-phase oxidation method in which titanium tetrachloride is reacted as a raw material with oxygen in a vapor phase. The sulfuric acid method is more preferable because the number average particle diameter of the primary particles of the obtained titanium oxide fine particles is easily controlled.

For the titanium oxide fine particles, it is desirable to use either one of the rutile type and anatase type crystal forms. In order to obtain fine anatase titanium oxide particles, phosphoric acid, a phosphate salt, a potassium salt, or the like is desirably added as a rutile transfer inhibitor when metatitanic acid is calcined.

On the other hand, in order to obtain fine particles of rutile titanium oxide, it is desirable to add a salt such as a lithium salt, a magnesium salt, a zinc salt, or an aluminum salt as a rutile transfer promoter, or a seed such as a slurry containing a microcrystalline rutile.

The manufacturing method of metal oxide fine particles of magnesium oxide, zinc oxide and cerium oxide includes a dry method of oxidizing metal vapor in air to produce zinc oxide; and a wet process in which a metal salt is neutralized by reaction with a base in an aqueous solution, and then washed with water, dried and calcined to produce zinc oxide. Among them, the wet method is preferably synthesized by a wet method because it is more likely to generate fine particles having a relatively small particle diameter that can be added to the toner surface.

The dielectric constant of the inorganic fine particles at 1MHz is preferably 20pF/m to 100 pF/m. An inorganic fine particle having a dielectric constant in this range is desirable because it undergoes rapid charge transfer with the second monomer unit. It is believed that this dielectric constant is closely related to charge transfer because it results from polarization within or between atoms.

The dielectric constant can be controlled by selecting the inorganic fine particles, or by controlling conditions and operations for changing the crystallinity of the particles in producing the inorganic fine particles, for example, by changing the reaction temperature or water pressure in a dry method, or by changing the pH or temperature in a wet method, or by, for example, ultrasonic treatment or bubbling treatment or the like during crystal formation. The dielectric constant is more preferably 20pF/m to 50 pF/m.

The inorganic fine particles are also characterized by being surface-treated with a compound having an alkyl group.

If the inorganic fine particles have been surface-treated with a compound having an alkyl group, the adhesion can be improved by interaction with the alkyl group contained in the polymer a, and a configuration is exhibited that facilitates rapid charge transfer from the inorganic fine particles to the second monomer unit of the toner particles.

Examples of the compound having an alkyl group include fatty acids, fatty acid metal salts, silicone oils, silane coupling agents, titanium coupling agents, and fatty alcohols.

Among them, in order to easily obtain the effect of the present invention, at least one compound selected from the group consisting of fatty acids, fatty acid metal salts, silicone oils, and silane coupling agents is preferable.

Examples of fatty acids and fatty acid metal salts include lauric acid, stearic acid, behenic acid, lithium laurate, lithium stearate, sodium stearate, zinc laurate, zinc stearate, calcium stearate, and aluminum stearate.

The following is a method of surface-treating inorganic fine particles with a fatty acid or a metal salt thereof. For example, may be in Ar or N₂The slurry containing the inorganic fine particles is put into an aqueous solution of sodium fatty acid in an atmosphere, and fatty acid is deposited on the surface of the perovskite-type crystal. May also be in Ar or N₂The slurry containing the inorganic fine particles is put into an aqueous solution of sodium fatty acid in an atmosphere, and an aqueous solution of a desired metal salt is added dropwise with stirring to deposit and adsorb the fatty acid metal salt on the surface of the perovskite-type crystal. For example, aluminum stearate can be adsorbed by using aluminum sulfate and an aqueous solution of sodium stearate.

Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, and alkyl-modified silicone oils such as α -methylstyrene-modified silicone oil and octyl-modified silicone oil.

The method of silicone oil treatment may be a known method. For example, the inorganic fine particles and the silicone oil may be mixed with a mixer; or the silicone oil may be sprayed onto the inorganic fine particles with a sprayer; alternatively, the silicone oil may be dissolved in a solvent and then the inorganic fine particles may be mixed therein. The processing method is not limited to these.

Examples of the silane coupling agent include hexamethyldisilazane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, hexadecyltrimethoxysilane and stearyltrimethoxysilane.

Examples of the aliphatic alcohol include ethanol, n-propanol, 2-propanol, n-butanol, t-butanol, n-octanol, stearyl alcohol and 1-tetracosanol. The method of treatment with the aliphatic alcohol may be, for example, a method of treating the inorganic fine particles after heating and evaporation at a temperature above the boiling point.

In these compounds, are selected from the group consisting of_4-24(preferably C)_4-18) At least one compound of the group consisting of alkyl compoundsIt is desirable to improve the charge rise because it further improves the interaction with the alkyl group of the first monomer unit.

Assuming that the carbon number of the alkyl group of the first polymerizable monomer is C_xThe carbon number of the alkyl group of the compound having an alkyl group is C_yThen C is_x/C_yPreferably 0.8 to 24.0, more preferably 1.0 to 10.0, because this enhances the interaction between the alkyl groups. When a plurality of polymerizable monomers or a plurality of compounds having an alkyl group are used, the carbon number is an average carbon number based on a molar ratio.

The number average particle diameter of the primary particles of the inorganic fine particles is preferably 20nm to 300 nm. A number average primary particle diameter within this range is desirable because it makes it easier for the inorganic fine particles to interact with both the first monomer unit and the second monomer unit of the polymer a having a block copolymer-like structure. 20nm to 200nm is more preferable.

The content of the inorganic fine particles is preferably 0.1 to 10.0 parts by mass with respect to 100 parts by mass of the toner particles.

In order to more easily obtain the effects of the present invention, the coverage of the toner particles with the inorganic fine particles is preferably 3 to 80 area%. More preferably, it is 10 to 80 area%, or still more preferably 20 to 80 area%. The coverage can be controlled by controlling the addition amount of the inorganic fine particles, external addition conditions, and the like.

The charge decay rate coefficient (charge decay rate coefficient) of the toner measured in an environment of 80% RH at 30 ℃ is preferably 3 to 100, or more preferably 3 to 60. A coefficient of charge decay rate within this range is desirable to control the loss of charge in a high temperature and high humidity environment. The charge decay rate coefficient can be controlled by controlling the kind and acid value of the binder resin, the kind of the inorganic fine particles, the surface treatment agent for the inorganic fine particles, and the coverage of the toner particles with the inorganic fine particles.

As described above, the strontium titanate fine particles can be obtained by the atmospheric pressure heating reaction method.

Reaction method by heating under normal pressure

Peptization of inorganic acids of hydrolyzed titanium compoundsThe substance was used as a titanium oxide source. For example, SO obtained by a sulfuric acid process may be used₃Metatitanic acid in an amount of preferably 1.0 mass% or less or more preferably 0.5 mass% or less, which has been peptized by adjusting pH to 0.8 to 1.5 with hydrochloric acid.

Nitrate or hydrochloride, etc. may be used as the strontium oxide source, and for example, strontium nitrate or strontium hydrochloride may be used.

Caustic may be used for the aqueous alkaline solution, with aqueous sodium hydroxide solution being preferred.

Factors affecting the particle size of the obtained strontium titanate particles include the mixing ratio of the titanium oxide source and the strontium oxide source in the reaction, the concentration of the titanium oxide source at the start of the reaction, and the temperature and the addition rate at the time of adding the alkaline aqueous solution, which can be appropriately adjusted to obtain the target particle size and particle size distribution. It is desirable to prevent contamination of carbon dioxide gas during the reaction by, for example, conducting the reaction in a nitrogen atmosphere to prevent the generation of hydrochloride.

Factors affecting the dielectric constant of the resulting strontium titanate particles include conditions and operations that disrupt the crystallinity of the particles. In order to obtain strontium titanate having a low dielectric constant, it is preferable to apply energy in a high-concentration reaction solution state to destroy crystal growth, and one specific method is to apply microbubbles with nitrogen gas, for example, during crystal growth.

SrO/TiO ratio of the mixing ratio of the titanium oxide source and the strontium oxide source in the reaction process₂Is preferably 0.9 to 1.4, or more preferably 1.05 to 1.20. If SrO/TiO₂When the molar ratio is 0.9 or more, unreacted titanium oxide is less likely to remain. The concentration of the titanium oxide source at the beginning of the reaction is taken as TiO₂May be 0.05 to 1.3mol/L, or more preferably 0.08 to 1.0 mol/L.

The temperature at which the aqueous alkaline solution is added is preferably about 60 ℃ to 100 ℃. With respect to the addition rate of the basic aqueous solution, a slower addition rate produces metal titanate particles having a larger particle size, and a faster addition rate produces metal titanate particles having a smaller particle size. The addition rate of the alkaline aqueous solution is preferably 0.001 to 1.2eq/h, or more preferably 0.002 to 1.1eq/h, relative to the raw material, and may be appropriately adjusted according to the desired particle diameter.

Acid treatment

It is preferable that the metal titanate particles obtained by the reaction by heating at atmospheric pressure are further acid-treated. When metal titanate particles are synthesized by a heating reaction under atmospheric pressure, if the mixing ratio of the titanium oxide source and the strontium oxide source exceeds 1.0 SrO/TiO₂In the molar ratio, the metal source other than the residual unreacted titanium after completion of the reaction may react with carbon dioxide gas in the air to generate impurities such as metal carbonate. Therefore, it is preferable to perform acid treatment after adding the alkaline aqueous solution to remove the unreacted metal source.

In the acid treatment, the pH is preferably adjusted to 2.5 to 7.0 or more preferably 4.5 to 6.0 with hydrochloric acid. In addition to hydrochloric acid, nitric acid, acetic acid, and the like may be used as the acid.

Coloring agent

The toner may also use a colorant. Examples of the colorant include the following.

Examples of black colorants include carbon black, and those in which black is obtained by blending a yellow colorant, a magenta colorant, and a cyan colorant. The pigment may be used alone as a colorant, but from the viewpoint of image quality of a full-color image, it is desirable to combine the dye and the pigment to improve the sharpness.

Examples of the pigment for magenta toner include c.i. pigment red 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:2, 48:3, 48:4, 49, 50, 51, 52, 53, 54, 55, 57:1, 58, 60, 63, 64, 68, 81:1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269 and 282; c.i. pigment violet 19; and c.i. vat reds 1,2, 10, 13, 15, 23, 29 and 35.

Examples of the dye for magenta toner include c.i. solvent reds 1,3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, and 121; c.i. disperse red 9; c.i. solvent violet 8, 13, 14, 21, 27; oil-soluble dyes such as c.i. disperse violet 1 and c.i. basic red 1,2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39 and 40; and basic dyes such as c.i. basic violet 1,3, 7, 10, 14, 15, 21, 25, 26, 27 and 28.

Examples of the pigment for cyan toner include c.i. pigment blue 2, 3, 15:2, 15:3, 15:4, 16 and 17; c.i. vat blue 6; and c.i. acid blue 45 and copper phthalocyanine pigments having 1 to 5 phthalimidomethyl substituents in the phthalocyanine skeleton.

Examples of the dye for cyan toner include c.i. solvent blue 70.

Examples of pigments for yellow toners include c.i. pigment yellow 1,2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, and 185; and c.i. vat yellows 1,3 and 20. Examples of the dye for yellow toner include c.i. solvent yellow 162.

The content of the colorant is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the binder resin.

Wax

Waxes may also be used in the toner. Examples of waxes include the following: hydrocarbon-based waxes such as microcrystalline wax, paraffin wax and Fischer-Tropsch wax; oxides of hydrocarbon waxes such as oxidized polyethylene wax and block copolymers thereof; waxes such as carnauba wax mainly composed of fatty acid esters; and waxes such as deoxidized carnauba wax composed of partially or completely deoxidized fatty acid esters.

Other examples include the following: saturated linear fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as brassidic acid, eleostearic acid, and stearidonic acid; saturated alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauba alcohol, hexacosanol and myricyl alcohol; polyols such as sorbitol; esters of fatty acids such as palmitic acid, stearic acid, behenic acid and montanic acid with alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauba alcohol, hexacosanol and myricyl alcohol; fatty acid amides such as linoleamide, oleamide, and lauramide; saturated fatty acid bisamides such as methylene bisstearamide, ethylene bisdecanamide, ethylene bislauramide and hexamethylene bisstearamide; unsaturated fatty acid amides such as ethylenebisoleamide, hexamethylenebisoleamide, N '-dioleyladipamide and N, N' -dioleylsebactamide; aromatic diamides such as m-xylene bisstearamide and N, N' -distearylmethisophthalamide; aliphatic metal salts (generally referred to as metal soaps) such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; waxes obtained by grafting vinyl monomers such as styrene and acrylic acid onto aliphatic hydrocarbon-based waxes; partial esterification products of polyhydric alcohols such as behenic acid monoglyceride and fatty acids; and methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils and fats.

The content of the wax is preferably 2.0 to 30.0 parts by mass with respect to 100 parts by mass of the binder resin.

Charge control agent

The toner may also contain a charge control agent, if necessary. A known charge control agent may be contained in the toner, and a metal compound of an aromatic carboxylic acid is particularly desirable because it is colorless and can provide a fast charging speed and stably maintain a uniform charge amount.

Examples of the negative charge control agent include salicylic acid metal compounds, naphthoic acid metal compounds, dicarboxylic acid metal compounds, macromolecular compounds having sulfonic acid or carboxylic acid in the side chain, macromolecular compounds having sulfonate salt or sulfonate ester in the side chain, macromolecular compounds having carboxylate salt or carboxylate ester in the side chain, and boron compounds, urea compounds, silicon compounds (silicon compounds), and calixarenes. The charge control agent may be added internally or externally to the toner particles.

The amount of the charge control agent added is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

Inorganic fine powder

In addition to the above inorganic fine particles, other inorganic fine powder may be contained in the toner as needed. The inorganic fine powder may be added internally or externally to the toner particles. As the external additive, for example, inorganic fine powder such as silica is desirable. Preferably, the inorganic fine powder is a powder hydrophobized with a hydrophobizing agent such as a silane compound or a silicone oil or a mixture of these.

For example, it is desirable to use fine silica powder produced by any method such as a precipitation method, a sol-gel method or other wet method in which silica is obtained by neutralizing sodium silicate, or a flame fusion method, an arc method or other dry method in which silica is obtained in a gas phase. Among them, fine silica powder produced by a sol-gel method or a flame fusion method is more desirable because it can more easily control the number average particle size of primary particles within a desired range.

As an external additive for improving fluidity, the specific surface area was 50m²G to 400m²An inorganic fine powder of 10m in specific surface area is desirable for stabilization of durability²G to 50m²An inorganic fine powder per g is desirable. In order to improve the fluidity and stabilize the durability at the same time, inorganic fine particles having a specific surface area within these ranges may be combined.

Developing agent

The toner may be used as a one-component developer, but from the viewpoint of obtaining stable image quality over a long period of time, it is preferable to mix it with a magnetic carrier and use it as a two-component developer to improve dot reproducibility. That is, a two-component developer containing a toner and a magnetic carrier is preferable, wherein the toner is the toner of the present invention.

Common, known magnetic carriers may be used, examples including surface-oxidized iron powder; non-oxidized iron powder; metal particles of iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium, rare earth, and the like; alloy particles and oxide particles of these; a magnet such as ferrite, and a resin carrier (so-called resin carrier) having a dispersed magnet including a binder resin carrying the magnet in a dispersed state.

When the toner is mixed with a magnetic carrier and used as a two-component developer, a good effect can be generally obtained if the carrier mixing ratio (toner concentration of the two-component developer) is 2 to 15 mass%, or more preferably 4 to 13 mass%.

Method for producing toner particles

The method of producing the toner particles is not particularly limited, and conventionally known methods such as a suspension polymerization method, an emulsion aggregation method, a melt kneading method, or a dissolution suspension method can be used.

The resulting toner particles can be used as toners as they are. Inorganic fine particles or other external additives may also be mixed with the resulting toner particles to obtain a toner, as necessary. Mixing of the toner particles with the inorganic fine particles and other external additives can be accomplished using a mixing apparatus such as a double cone mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a nauta mixer, a Mechano Hybrid (Nippon biscuit and Engineering), or a Nobilta (Hosokawa micron).

The external additive is preferably used in an amount of 0.1 to 10.0 parts by mass relative to 100 parts by mass of the toner particles.

The following describes methods of measuring various physical properties of the toner and the raw material.

Analytical method

Measurement of volume resistivity of inorganic fine particles

The volume resistivity of the inorganic fine particles was measured as follows. As equipment, an electrometer/high resistance system model Keithley Instruments 6517 was used. Electrodes having a diameter of 25mm were connected, inorganic fine particles were placed between the electrodes to a thickness of about 0.5mm, and the distance between the electrodes under a load of about 2.0N was measured.

The resistance value was measured when a voltage of 1,000V was applied to the inorganic fine particles for 1 minute, and the volume resistivity was calculated according to the following formula.

Volume resistivity (Ω · cm) ═ R × L

R: resistance value (omega)

L: distance between electrodes (cm)

Separation of inorganic fine particles from toner

The inorganic fine particles can also be separated and measured from the toner by the following method.

200g of sucrose (Kishida Chemical) was added to 100mL of ion-exchanged water and dissolved in a hot water bath to prepare a concentrated sucrose solution. 31g of a concentrated sucrose solution and 6mL of Contaminon N (a 10 mass% aqueous solution of a precision instrumental washing neutral detergent of pH7, which contains a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries) were added to a centrifuge tube to prepare a dispersion solution. To the dispersion solution, 1g of toner was added, and the toner lumps were broken with a doctor blade or the like.

The tube was shaken in a shaker at 350 rpm for 20 minutes. After shaking, the solution was transferred to a glass tube (50mL) for a rotary rotor, and centrifuged at 3,500rpm for 30 minutes in a centrifuge. After the centrifugal separation, the toner exists in the uppermost layer within the glass tube, and the inorganic fine particles exist in the aqueous solution of the lower layer. The lower aqueous solution was collected and centrifuged to separate sucrose from the inorganic fine particles, which were collected. The centrifugal separation is repeated as necessary, and once sufficiently separated, the dispersion is dried and the inorganic fine particles are collected.

When a plurality of kinds of inorganic fine particles are added, they can be selected by centrifugal separation or the like.

Measurement of dielectric constant

The complex dielectric constant at a frequency of 1MHz was measured after calibration at 1kHz and 1MHz using a 284A precision LCR instrument (Hewlett Packard). 39,200kPa (400 kg/cm) was applied to the inorganic fine particles to be measured²) The load of (3) is 5 minutes, and the sample is measured in the form of a disk having a diameter of 25mm and a thickness of 1mm or less (preferably 0.5 to 0.9 mm). The measurement sample was mounted on ARES (Rheometric scientific FE) equipped with a dielectric constant measuring jig (electrode) having a diameter of 25mm, and measured at a frequency of 1MHz under a load of 0.49N (50g) in an atmosphere of 25 ℃.

Measurement of charge decay Rate coefficient of toner

The charge decay rate coefficient of the toner was measured using an NS-D100 electrostatic diffusivity measuring device (Nano Seeds).

First, about 100mg of toner was placed in a sample pan and scraped to smooth the surface. The sample disk was exposed to X-rays for 30 seconds with an X-ray static eliminator to remove charge from the toner. The sample plate after the neutralization was placed on the measurement plate. While a metal plate for zero correction of the surface voltmeter was installed as a control. Before the measurement, the measurement plate with the sample was left in an environment of 30 ℃ and 80% RH for 1 hour or more.

The measurement conditions were set as follows.

Charging time: 0.1 second

Measuring time: 1,800 seconds

Measurement interval: 1 second

Discharge polarity: -

An electrode: is that

The initial potential was set at-600V, and the change in surface potential immediately after charging was measured. The results were fitted to the following equation to find the charge decay rate coefficient α.

V_t＝V₀exp(-αt^1/2)

V_t: surface potential (V) at time t

V₀: initial surface potential (V)

t: time after charging (second)

α: coefficient of charge decay rate

Number average particle diameter of primary particles of inorganic fine particles

The number average particle diameter of the primary particles of the inorganic fine particles was measured using an S-4800Hitachi ultra High resolution field emission scanning electron microscope (FE-SEM) (Hitachi High-Technologies).

The measurement was performed on the toner after mixing the inorganic fine particles.

In the case where the magnification was set to 50,000 times, a photograph was taken and further magnified twice, the maximum diameter (major axis diameter) a and the minimum diameter (minor axis diameter) b of the inorganic fine particles were measured from the obtained FE-SEM photograph, and (a + b)/2 was regarded as the particle diameter of these particles. The diameters of 100 randomly selected inorganic fine particles were measured, and the average value was calculated and regarded as the number average diameter of the primary particles of the inorganic fine particles.

Method for measuring content of monomer unit derived from each polymerizable monomer in polymer a

Under the following conditions, by¹H-NMR measured the content of monomer units derived from each polymerizable monomer in the polymer A.

A measuring device: FT NMR apparatus JNM-EX400(JEOL Ltd.)

Measuring frequency: 400MHz

Pulse conditions are as follows: 5.0 mus

Frequency range: 10,500Hz

Cumulative number of times: 64

Measuring the temperature: 30 deg.C

Sample preparation: deuterated chloroform (CDCl) was added by placing 50mg of the measurement sample in a sample tube with an inner diameter of 5mm₃) As a solvent, and dissolved in a thermostatic bath at 40 ℃.

In the obtaining of¹In the H-NMR chart, a peak independent of peaks assigned to constituent elements derived from other monomer units is selected from among peaks assigned to constituent elements derived from monomer units of the first polymerizable monomer, and the integral value S of the peak is calculated₁. Similarly, from among the peaks ascribed to the constituent elements of the monomer unit derived from the second polymerizable monomer, a peak independent of the peaks ascribed to the constituent elements derived from other monomer units is selected, and the integrated value S of the peak is calculated₂。

When the third polymerizable monomer is used, a peak independent of peaks ascribed to constituent elements derived from other monomer units is selected from among peaks ascribed to constituent elements derived from monomer units of the third polymerizable monomer, and an integrated value S of the peak is calculated₃。

Using integral values S₁、S₂And S₃The content of the monomer unit derived from the first polymerizable monomer was determined as follows. n is₁、n₂And n₃Is the number of hydrogen atoms in the constituent element to which the peak observed for each segment belongs.

The content (% by mole) of the monomer unit derived from the first polymerizable monomer is ═ by mole ═ by

{(S₁/n₁)/((S₁/n₁)+(S₂/n₂)+(S₃/n₃))}×100。

The content of the monomer unit derived from the second polymerizable monomer and the third polymerizable monomer is similarly determined as shown below.

The content (% by mole) of the monomer unit derived from the second polymerizable monomer is ═ by mole ═ by

{(S₂/n₂)/((S₁/n₁)+(S₂/n₂)+(S₃/n₃))}×100。

The content (% by mole) of the monomer unit derived from the third polymerizable monomer is ═ by mole ═ by

{(S₃/n₃)/((S₁/n₁)+(S₂/n₂)+(S₃/n₃))}×100。

When a polymerizable monomer containing no hydrogen atom in the constituent elements other than the vinyl group is used in the polymer A, the polymerizable monomer is used¹³C-NMR in the presence of¹³C as a measurement core, and measuring in a single-pulse mode¹The ratio was calculated in the same manner as in H-NMR.

When the toner is manufactured by the suspension polymerization method, an independent peak may not be observed because peaks of the release agent and other resins overlap. Therefore, the ratio of the monomer units derived from each polymerizable monomer in the polymer a may not be calculated. In this case, the polymer a' can be produced by performing similar suspension polymerization without using a release agent or other resins, and analyzed as the polymer a.

SP value calculation method

SP₁₂And SP₂₂The following calculation method proposed by Fedors was obtained as follows.

The evaporation energy (. DELTA.ei) (cal/mol) and the molar volume (. DELTA.vi) (cm) were determined for the atoms or atomic groups in the molecular structure of each polymerizable monomer from the tables described in "Polym. Eng. Sci.,14(2)," 147-154(1974) "³Mol), will be (4.184 × Σ Δ ei/Σ Δ vi))^0.5Considered as SP value (J/cm)³)^0.5。

For atoms or atomic groups in the molecular structure of the same polymerizable monomer in which the double bond is broken by polymerization, SP is calculated by a similar method₁₁And SP₂₁。

Method for measuring melting point

The melting points of polymer a and the mold release agent were measured using DSC Q1000(TA Instruments) under the following conditions.

Temperature rise rate: 10 ℃/min

Measurement start temperature: 20 deg.C

Measurement of the termination temperature: 180 deg.C

The melting points of indium and zinc were used for temperature correction in the detection section of the device, and the heat of fusion of indium was used for correction of the calorific value.

Specifically, 5mg of the sample was accurately weighed into an aluminum pan, and differential scanning calorimetry was performed. An empty silver disc was used as a control.

The peak temperature of the maximum endothermic peak during the first temperature rise was taken as the melting point.

When a plurality of peaks are present, the maximum endothermic peak is the peak having the largest endothermic amount.

Measurement of molecular weight of THF-soluble component of resin

The molecular weight (Mw) of the THF soluble component of polymer a was measured by Gel Permeation Chromatography (GPC) as follows.

First, the sample was dissolved in Tetrahydrofuran (THF) over the course of 24 hours at room temperature. The resulting solution was filtered through a solvent-resistant membrane filter (Maishori Disk, Tosoh Corp.) having a pore diameter of 0.2 μm to obtain a sample solution. The concentration of the THF-soluble component in the sample solution was adjusted to about 0.8 mass%. The measurement was performed under the following conditions using the sample solution.

The system comprises the following steps: HLC8120GPC (detector: RI) (Tosoh Corp.)

Column: shodex KF-801, 802, 803, 804, 805, 806, 807 (7 in total) (Showa Denko)

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0mL/min

Oven temperature: 40.0 deg.C

Sample injection amount: 0.10mL

A molecular weight calibration curve prepared using a standard polystyrene resin (product name: TSK standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500, Tosoh Corp.) was used to calculate the molecular weight of the sample.

Method for measuring acid value

The acid number is the mg of potassium hydroxide required to neutralize the acid contained in 1g of the sample. The acid value of the polymer A in the present invention was measured in accordance with JIS K0070-1992 by the following specific measurement procedure.

(1) Preparation of reagents

A phenolphthalein solution was obtained by dissolving 1.0g of phenolphthalein in 90mL of ethanol (95 vol%) and adding ion-exchanged water to a total of 100 mL.

7g of special grade potassium hydroxide was dissolved in 5mL of water and brought to 1L by adding ethanol (95 vol%). It was placed in an alkali-resistant container while avoiding contact with carbon dioxide or the like, allowed to stand for 3 days, and filtered to obtain a potassium hydroxide solution. The resulting potassium hydroxide solution was stored in an alkali-resistant container. The factor of the potassium hydroxide solution was determined from the amount of potassium hydroxide solution required for neutralization when 25mL of 0.1mol/L hydrochloric acid was put in an Erlenmeyer flask (Erlenmeyer flash), several drops of phenolphthalein solution were added, and titration was performed with the potassium hydroxide solution. 0.1mol/L hydrochloric acid was prepared according to JIS K8001-.

(2) Operation of

(A) Main test

2.0g of a comminuted sample of polymer A were accurately weighed into a 200mL Erlenmeyer flask, and 100mL of toluene: the mixed solution of ethanol (2: 1) dissolved the sample over the course of 5 hours. Several drops of phenolphthalein solution were then added as an indicator and titration was performed using potassium hydroxide solution. The titration endpoint was considered to be a pale pink color of the indicator for 30 seconds.

(B) Blank test

Titration was performed by the same procedure except that no sample was used (i.e., only a mixed solution of toluene: ethanol (2: 1)) was used.

(3) The acid value was calculated by substituting the obtained result into the following formula:

A＝[(C-B)×f×5.61]/S

where A is the acid number (mg KOH/g), B is the amount of potassium hydroxide solution added (mL) in the blank test, C is the amount of potassium hydroxide solution added (mL) in the main test, f is a factor of the potassium hydroxide solution, and S is the mass of the sample (g).

Method for measuring coverage rate of external additive

To determine the coverage of the external additive, the surface Image of the toner particles obtained with a S-4800Hitachi ultra high resolution field emission Scanning Electron Microscope (SEM) was analyzed using Image analysis software (Image-Pro Plus ver.5.0, Nippon Roper).

The inorganic fine particles present on the surface of the toner particles were observed with the SEM apparatus.

During observation, a position where the surface of the toner particle is smooth is selected as much as possible.

An image in which the inorganic fine particles are extracted only on the toner particle surface is binarized, and the ratio of the area occupied by the inorganic fine particles to the area of the toner particle surface is calculated. The same operation is performed for 10 toner particles, and an arithmetic average value is calculated.

Weight average particle diameter of toner particles (D4)

Measurement was performed using 25,000 effective measurement channels using a Multisizer (registered trademark) 3Coulter Counter precision particle size distribution analyzer (Beckman Coulter, Inc.) based on the orifice resistance method and equipped with a 100 μm orifice tube, and an accessory-dedicated Beckman Coulter Multisizer 3Version 3.51 software (Beckman Coulter, Inc.) for setting measurement conditions and analyzing measurement data, and the measurement data was analyzed to calculate the weight average particle diameter of the toner particles (D4).

The aqueous electrolyte solution used for the measurement may be, for example, a solution in which special sodium chloride is dissolved in ion-exchanged water to a concentration of about 1 mass%, such as ISOTON II (Beckman Coulter, Inc.).

Prior to measurement and analysis, dedicated software settings were made as follows.

On the "standard measurement method (SOM) modification" screen of the dedicated software, the total count in the control mode was set to 50,000 particles, the number of measurements was set to 1, and the Kd value was set to a value obtained using "standard particles 10.0 μm" (Beckman Coulter, Inc.). The threshold and noise level are automatically set by pressing the "threshold/noise level measurement button". The current was set to 1600 μ a, the gain was set to 2, the electrolyte solution was set to ISOTON II, and the measured port tube was flushed into examination.

On the "pulse-to-particle size conversion setting" screen of the dedicated software, the element spacing was set to the logarithmic particle size, the particle size elements were set to 256, and the particle size range was set to 2 μm to 60 μm.

The specific measurement method is as follows.

(1) About 200mL of the aqueous electrolyte solution was added to a dedicated 250mL round bottom beaker of Multisizer 3, and the beaker was placed on a sample stage and stirred counterclockwise with a stirring rod at a speed of 24 revolutions per second. Then the dirt and air bubbles in the mouth tube are removed through the function of 'mouth tube flushing' of the special software.

(2) 30mL of the same aqueous electrolyte solution was placed in a 100mL glass beaker with a flat bottom, and about 0.3mL of a diluent of "Contaminon N" (10% by mass aqueous solution of neutral detergent for precision instrument washing at pH7, which contains a nonionic surfactant, an anionic surfactant, and an organic builder) diluted 3-fold by mass with ion-exchanged water was added.

(3) A specific amount of ion-exchanged water was put into a water tank of an Ultrasonic disperser (Ultrasonic Dispersion system Tetora 150, Nikkaki Bios) having an electric power output of 120W and equipped with two built-in oscillators having an oscillation frequency of 50kHz and a phase shifted from each other by 180 degrees, and about 2mL of Contaminon N was added to the water tank.

(4) The beaker of the above (2) was placed in a beaker fixing hole of an ultrasonic disperser, and the ultrasonic disperser was operated. The height position of the beaker is adjusted so that the resonance state of the liquid level of the aqueous electrolyte solution in the beaker is maximized.

(5) The aqueous electrolyte solution in the beaker of (4) was exposed to ultrasonic waves while about 10mg of toner was added little by little to the aqueous electrolyte solution and dispersed. The ultrasonic dispersion then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the tank was appropriately adjusted to 10 ℃ to 40 ℃.

(6) The aqueous electrolyte solution of (5) in which the toner was dispersed was dropped with a pipette into the round-bottom beaker of (1) set on the sample stage, and adjusted to a measured concentration of about 5%. Then, measurement was performed until the number of particles measured reached 50,000.

(7) The measurement data was analyzed by dedicated software attached to the apparatus, and the weight average particle diameter (D4) was calculated. When the chart/volume% is set in the dedicated software, the weight average particle diameter (D4) is the "average diameter" on the "analysis/volume statistic (arithmetic mean)" screen.