JP2015191108A - electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner achieving both of low-temperature fixability and heat-resistant storage property and having excellent document offset resistance, and a production method of the toner.SOLUTION: The electrophotographic toner has a core-shell structure, in which the core part comprises a polyester (A) obtained by polymerization condensation of an alcohol component and a carboxylic acid component, and the shell part comprises a polyester (B) obtained by polymerization condensation of an alcohol component and a carboxylic acid component containing a succinic acid having an alkyl group and/or a succinic acid having an alkenyl group (ASAN). The polyester (B) has a glass transition temperature of 35°C or higher and 80°C or lower; and the glass transition temperature of the polyester (B) is higher by 3°C or more than the glass transition temperature of the polyester (A). An ASAN content (mol%) XA in the carboxylic acid component of the polyester (A) and an ASAN content (mol%) XB in the carboxylic acid component of the polyester (B) satisfy a relationship of XB-XA≥15. A production method of the above toner is also disclosed.

Description

  The present invention relates to an electrophotographic toner and a method for producing the same.

In the field of electrophotography, with the development of electrophotographic systems, there is a need for toners with excellent low-temperature fixability that can cope with higher image quality and higher speed, and can also save energy from the viewpoint of consideration for the global environment. Has been. However, a toner that can be fixed at a low temperature is poor in heat resistance because it melts at a low temperature. In order to improve this trade-off, a toner having a core-shell structure has been proposed.
In Patent Document 1, as an electrophotographic toner excellent in low-temperature fixability and charging stability, an alcohol component containing an aliphatic diol having 2 to 6 carbon atoms and a carboxylic acid component not containing alkenyl succinic acid are used. Is an amorphous resin (B) obtained by polycondensation of an alcohol component and a carboxylic acid component containing alkenyl succinic acid. An electrophotographic toner containing core-shell particles as a binder resin is disclosed.

  Further, Patent Document 2 is excellent in low-temperature fixability, excellent in heat-resistant storage properties, excellent in toner particle crush resistance, and does not generate toner fine powder in the image forming apparatus during long-term use. In order to provide a toner that is effective in suppressing filming and toner scattering of the intermediate transfer member and the photosensitive member, toner particles are obtained by agglomerating and fusing resin fine particles containing at least an amorphous polyester resin. A first aggregating step of aggregating at least resin fine particles containing at least the non-crystalline polyester resin to produce a dispersion of a first toner particle precursor; and the first toner A mixing step of mixing a dispersion of particle precursor and a dispersion of polyester resin fine particles having a carboxyl group to produce a dispersion of a second toner particle precursor After the mixing step, the second toner particle precursors, is at least aggregated, the toner production method and having a second aggregation step of forming the toner particles, is disclosed.

JP2013-222001A JP 2010-145611 A

However, even a toner having a core-shell structure as in Patent Documents 1 and 2 cannot be said to be able to satisfy both conflicting characteristics of low-temperature fixability and heat-resistant storage stability at a sufficient level. Since the resin in the core and the resin in the shell are compatible at the time of fixing, the document offset resistance in the printed matter after fixing is insufficient, and further improvement is necessary.
An object of the present invention is to provide an electrophotographic toner that solves the above-described problems, has both low-temperature fixability and heat-resistant storage stability, and has excellent document offset resistance, and a method for producing the same.

  The present inventors provide a toner having a core-shell structure, in which the glass transition temperature in the polyester of the core portion and the polyester of the shell portion has a specific relationship, and can be contained as a carboxylic acid component of each polyester. When the total content of succinic acid having an alkyl group of 8 or more and 14 or less and succinic acid having an alkenyl group of 8 or more and 14 or less carbon atoms satisfies a specific quantitative relationship, both low-temperature fixability and heat-resistant storage stability are achieved. The present inventors have found that an electrophotographic toner having excellent document offset resistance can be obtained.

That is, the present invention provides the following [1] and [2].
[1] An electrophotographic toner having a core-shell structure,
The core part is obtained by polycondensation of an alcohol component and a carboxylic acid component which may contain succinic acid having an alkyl group having 8 to 14 carbon atoms and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms. Containing polyester (A),
Polyester obtained by polycondensing an alcohol component and a carboxylic acid component containing a succinic acid having an alkyl group having 8 to 14 carbon atoms and / or an alkenyl group having 8 to 14 carbon atoms in a shell portion Containing (B),
An electrophotographic toner in which the polyester (A) and the polyester (B) satisfy the following (i) to (iii).
(I) The glass transition temperature of the polyester (B) is 35 ° C. or higher and 80 ° C. or lower.
(Ii) The glass transition temperature of the polyester (B) is 3 ° C. or more higher than the glass transition temperature of the polyester (A).
(Iii) The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (A) is XA The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of polyester (B) is XB. Then, the relationship XB−XA ≧ 15 is satisfied.

[2] A method for producing an electrophotographic toner comprising the following steps (1) to (3).
Step (1): Step of aggregating the resin particles (a) containing the polyester (A) to obtain aggregated particles (1) Step (2): Containing the polyester (B) in the aggregated particles (1) Step for obtaining aggregated particles (2) by adding resin particles (b) to be processed Step (3): Step for obtaining toner particles having a core-shell structure by fusing the aggregated particles (2)

  The electrophotographic toner of the present invention has both low-temperature fixability and heat-resistant storage stability, and is excellent in document offset resistance.

The reason why the electrophotographic toner of the present invention has both good low-temperature fixability and heat-resistant storage stability and excellent document offset resistance is not clear, but is considered as follows.
The electrophotographic toner of the present invention has a core-shell structure. In a toner having a core-shell structure, the core portion contains a resin component that can be melted at a temperature sufficiently low to exhibit low-temperature fixability, and the shell portion suppresses fusion between toner particles due to melting during storage. By using a resin having a glass transition temperature sufficiently higher than that of the core part, it is considered that both low-temperature fixability and heat-resistant storage stability can be achieved, but when the shell part does not completely cover the core part or When the resin of the core part and the resin of the shell part are easily compatible with each other by heating at the time of manufacture, the core-shell structure cannot be maintained by heating, resulting in poor heat-resistant storage stability and poor document offset resistance after fixing. On the other hand, the electrophotographic toner of the present invention has a succinic acid having an alkyl group having 8 to 14 carbon atoms and / or a succinic acid having an alkenyl group having 8 to 14 carbon atoms in at least the polyester used in the shell portion. Total of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (A) contained in the core part, which contains an acid component Succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (B) contained in the shell part in XA content (mol%) When the total acid content (mol%) is XB, the relationship XB-XA ≧ 15 is satisfied. As described above, it is considered that the polyester having a long-chain alkyl group or a long-chain alkenyl group in the side chain is reduced in cohesion by suppressing the approach between molecules. By containing a sufficient amount of such polyester in the shell part, the compatibility between the core part and the shell part can be reduced, and the surface tension on the shell part side can be made lower than the surface tension on the core part side. . Thus, it is considered that the shell component can be uniformly covered on the surface of the toner particles at the time of toner production. Further, since the polyester in the shell portion has a weak cohesive force, it is considered that the polyester in the shell portion remains in the vicinity of the toner surface even after toner fixing, thereby improving the document offset resistance of the printed matter.

[Electrophotographic toner]
The electrophotographic toner of the present invention is an electrophotographic toner having a core-shell structure, wherein the core portion has an alcohol component and an alkyl group having 8 to 14 carbon atoms and / or 8 to 14 carbon atoms. A polyester (A) obtained by polycondensation with a carboxylic acid component which may contain succinic acid having an alkenyl group of
Polyester obtained by polycondensing an alcohol component and a carboxylic acid component containing a succinic acid having an alkyl group having 8 to 14 carbon atoms and / or an alkenyl group having 8 to 14 carbon atoms in a shell portion Containing (B),
The polyester (A) and the polyester (B) satisfy the following (i) to (iii).
(I) The glass transition temperature of the polyester (B) is 35 ° C. or higher and 80 ° C. or lower.
(Ii) The glass transition temperature of the polyester (B) is 3 ° C. or more higher than the glass transition temperature of the polyester (A).
(Iii) The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (A) is XA The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of polyester (B) is XB. Then, the relationship XB−XA ≧ 15 is satisfied.

  Hereafter, each component etc. which are used for this invention are demonstrated.

<Core part>
(Polyester (A))
The core part contains polyester (A).
The content of the polyester (A) in the resin constituting the core portion is preferably in the resin constituting the core portion from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, still more preferably 98% by mass or more, still more preferably substantially 100% by mass, and still more preferably 100% by mass. .
The polyester (A) is preferably an amorphous polyester from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance.
In the present invention, the amorphous polyester means a ratio between a softening point and a maximum endothermic peak temperature measured by a differential scanning calorimeter (DSC), that is, (softening point (° C)) / (maximum endothermic peak temperature (° C)). The crystallinity index defined by is greater than 1.4 or less than 0.6. From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, it is preferably less than 0.6 or more than 1.4 and 4 or less, more preferably less than 0.6 or 1 5 or more and 4 or less, more preferably less than 0.6 or 1.5 or more and 3 or less, and still more preferably less than 0.6 or 1.5 or more and 2 or less. The crystallinity index can be appropriately determined according to the production conditions such as the type and ratio of the raw material monomers, the reaction temperature, the reaction time, and the cooling rate. The endothermic maximum peak temperature refers to the temperature of the peak having the maximum peak area among the observed endothermic peaks. The maximum peak temperature is the melting point if the difference from the softening point is within 20 ° C., and the peak temperature due to the glass transition if the difference from the softening point exceeds 20 ° C.

The polyester (A) is obtained by polycondensation of an alcohol component and a carboxylic acid component.
[Alcohol component]
Examples of the alcohol component that is a raw material monomer of the polyester (A) include aliphatic diols having 2 to 12 main chain carbon atoms, aromatic diols, alicyclic diols, trivalent or higher polyhydric alcohols, or those having 2 carbon atoms. Examples include adducts having 4 or less alkylene oxide (average added mole number of 1 to 16).
Specific examples of the aliphatic diol having 2 to 12 carbon atoms in the main chain include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, , 4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1, Examples thereof include 12-dodecanediol and neopentyl glycol.
Specific examples of the aromatic diol include bisphenol A such as polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene adduct of 2,2-bis (4-hydroxyphenyl) propane. And alkylene oxide adducts.
Specific examples of the alicyclic diol include 2,2-bis (4-hydroxycyclohexyl) propane (hydrogenated bisphenol A).
Specific examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

The alcohol component is preferably an aromatic diol, more preferably an alkylene oxide adduct of bisphenol A, from the viewpoint of improving low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, and 2,2-bis. More preferred are polyoxypropylene adducts of (4-hydroxyphenyl) propane and polyoxyethylene adducts of 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4-hydroxyphenyl) propane A polyoxyethylene adduct is still more preferable.
From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, the content when the alkylene oxide adduct of bisphenol A is contained as the alcohol component is the content of the alcohol component of the polyester (A). , Preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably substantially 100% by mass, and even more preferably 100% by mass. %.

[Carboxylic acid component]
Examples of the carboxylic acid component that is a raw material monomer of the polyester (A) include dicarboxylic acids and trivalent or higher polyvalent carboxylic acids.
In the present invention, the carboxylic acid component includes not only dicarboxylic acids and trivalent or higher polyvalent carboxylic acids, but also anhydrides thereof and alkyl esters having 1 to 3 carbon atoms.
Examples of the dicarboxylic acid include aliphatic dicarboxylic acid, aromatic dicarboxylic acid, and alicyclic dicarboxylic acid.
Specific examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, azelaic acid And succinic acid having an alkyl group having 1 to 14 carbon atoms, preferably 8 to 14 carbon atoms, and succinic acid having an alkenyl group having 2 to 14 carbon atoms, preferably 8 to 14 carbon atoms. .
Specific examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid and the like.
Specific examples of the alicyclic dicarboxylic acid include cyclohexane dicarboxylic acid.
Specific examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalene tricarboxylic acid, pyromellitic acid and the like.

As the carboxylic acid component, fumaric acid, adipic acid, sebacic acid, succinic acid having an alkenyl group having 8 to 14 carbon atoms, and anhydride thereof are preferable from the viewpoint of improving low-temperature fixability of the toner, and adipic acid and dodecenyl succinic acid are preferable. An acid anhydride is more preferable. Further, from the viewpoint of improving the heat resistant storage stability of the toner, isophthalic acid, terephthalic acid, trimellitic acid and anhydrides thereof are preferable, and terephthalic acid and trimellitic acid anhydride are more preferable.
The alcohol component and the carboxylic acid component can be used singly or in combination of two or more.

[Molar ratio of alcohol component to carboxylic acid component]
The molar ratio of the carboxylic acid component to the alcohol component (carboxylic acid component / alcohol component) is preferably 0.7 or more and 1. from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. 2 or less, more preferably 0.75 or more and 1.1 or less.

<Shell part>
(Polyester (B))
The shell portion contains polyester (B).
The content of the polyester (B) in the resin constituting the shell portion is preferably in the resin constituting the shell portion from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, still more preferably 98% by mass or more, still more preferably substantially 100% by mass, and still more preferably 100% by mass. .
The polyester (B) is preferably an amorphous polyester from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance.
The polyester (B) is obtained by polycondensation of an alcohol component and a carboxylic acid component containing succinic acid having an alkyl group having 8 to 14 carbon atoms and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms. It is done.

[Alcohol component]
Examples of the alcohol component that is a raw material monomer for the polyester (B) include aliphatic diols having 2 to 12 carbon atoms in the main chain, aromatic diols, alicyclic diols, trivalent or higher polyhydric alcohols, or those having 2 carbon atoms. Examples include adducts having 4 or less alkylene oxide (average added mole number of 1 to 16).
Specific examples of the aliphatic diol, the aromatic diol, the alicyclic diol, and the trihydric or higher polyhydric alcohol having 2 to 12 main chain carbon atoms are the same as in the case of the polyester (A).

As the alcohol component, an aromatic diol and an alicyclic diol are preferable from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, and an alkylene oxide adduct of bisphenol A and 2 2-bis (4-hydroxycyclohexyl) propane is more preferred. Further, from the viewpoint of maintaining the core-shell structure of the toner by controlling the compatibility between the core portion and the shell portion, 2,2-bis (4-hydroxyphenyl) propane polyoxypropylene adduct and 2,2-bis A polyoxyethylene adduct of (4-hydroxyphenyl) propane is preferred, and a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane is more preferred. In addition, from the viewpoint of improving document offset resistance, it is preferable to contain 2,2-bis (4-hydroxycyclohexyl) propane as the alcohol component of the polyester (B).
From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, the content of the alkylene oxide adduct of bisphenol A as the alcohol component is the alcohol component of the polyester (B). Among these, preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, still more preferably 75% by mass or more, and preferably 100% by mass or less, more preferably 90% by mass. % Or less.
Further, from the viewpoint of maintaining the core-shell structure of the toner by controlling the compatibility between the core portion and the shell portion, the alkylene oxide adduct of bisphenol A that can be contained as an alcohol component of the polyester (A) and the polyester (B) The types of oxides are preferably different from each other. That is, when the polyester (B) contains a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane as an alcohol component, the alcohol component of the polyester (A) contains 2,2-bis ( It is preferable to contain a polyoxyethylene adduct of 4-hydroxyphenyl) propane, and when polyester (B) contains a polyoxyethylene adduct of 2,2-bis (4-hydroxyphenyl) propane as an alcohol component It is preferable that the alcohol component of the polyester (A) contains a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane.

[Carboxylic acid component]
The carboxylic acid component which is a raw material monomer of the polyester (B) includes succinic acid having an alkyl group having 8 to 14 carbon atoms and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms. Since the polyester (B) has a long-chain alkyl group or a long-chain alkenyl group in the side chain, access between molecules is suppressed, and the cohesiveness of the polyester (B) is lowered. By using polyester (B) having a low cohesive force for the shell part, the surface tension of the shell part is reduced below the surface tension of the core part, and the shell part is likely to spread uniformly on the core part, so that homogeneous core-shell particles To form a toner having excellent heat-resistant storage stability. Further, since the polyester in the shell portion has a weak cohesive force, the polyester (B) in the shell portion remains in the vicinity of the toner surface even after the toner is fixed, thereby improving the document offset resistance of the printed matter. The succinic acid having an alkyl group having 8 to 14 carbon atoms and / or the succinic acid having an alkenyl group having 8 to 14 carbon atoms includes those anhydrides.
The carbon number of the alkyl group or alkenyl group of the succinic acid is 8 or more and 14 or less, preferably 10 or more and 12 or less, from the viewpoint of improving the document offset resistance of the toner. The alkyl group or alkenyl group of succinic acid may be any, but is preferably an alkenyl group.
The succinic acid having an alkyl group having 8 to 14 carbon atoms and / or the succinic acid having an alkenyl group having 8 to 14 carbon atoms has both low-temperature fixability and heat-resistant storage stability of the toner, and document offset resistance. From the viewpoint of improving the above, octyl succinic acid, decenyl succinic acid, undecenyl succinic acid, dodecenyl succinic acid, and tetradecenyl succinic acid are preferable, and dodecenyl succinic acid is more preferable.

  The total content of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (B) depends on the low-temperature fixability and heat resistance of the toner. From the viewpoint of achieving both storability and improving document offset resistance, it is 15 mol% or more, preferably 16 mol% or more, more preferably 20 mol% or more, and from the same viewpoint, preferably 60 mol%. Hereinafter, it is more preferably 55 mol% or less, and still more preferably 53 mol% or less.

  In the case where succinic acid having an alkyl group having 8 to 14 carbon atoms and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms is used in the carboxylic acid component of the polyester (A), From the viewpoint of maintaining the core-shell structure of the toner by controlling the compatibility with the shell portion, the content is limited. That is, the total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (A) is XA, When the total content (mol%) of the succinic acid having an alkyl group having 8 to 14 carbon atoms and the alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (B) is XB. From the standpoint of maintaining the core-shell structure of the toner by controlling the compatibility between the core portion and the shell portion, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving document offset resistance, XB-XA ≧ 15, preferably XB-XA ≧ 16, more preferably 60 ≧ XB-XA ≧ 16. When XA and XB satisfy the relationship of XB-XA ≧ 15, the compatibility between the polyester (A) in the core part and the polyester (B) in the shell part is moderately reduced, and the cohesiveness of the shell part is reduced. The toner particles having a core-shell structure in which the shell layer covers the core portion thinly and uniformly can be produced uniformly and stably.

Examples of the carboxylic acid component other than succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the polyester (B) include the carboxylic acid component of the polyester (A). What was illustrated can be used suitably.
The alcohol component and the carboxylic acid component can be used singly or in combination of two or more.

[Molar ratio of alcohol component to carboxylic acid component]
The molar ratio of the carboxylic acid component to the alcohol component (carboxylic acid component / alcohol component) is preferably 0.7 or more and 1. from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. 2 or less, more preferably 0.75 or more and 1.1 or less.

(Physical properties of polyester (A) and (B))
The glass transition temperature of the polyester (A) contained in the core portion is 75 ° C. or less, preferably 70 ° C. or less, more preferably 60 ° C. or less, from the viewpoint of improving the low-temperature fixability of the toner. Further, from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, it is preferably 32 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 43 ° C. or higher.
The glass transition temperature of the polyester (B) contained in the shell portion is 35 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, from the viewpoint of improving the heat resistant storage stability and document offset resistance of the toner. is there. Further, from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, the temperature is 80 ° C. or lower, preferably 75 ° C. or lower, more preferably 70 ° C. or lower.
By making the glass transition temperature of the shell part higher than the glass transition temperature of the core part, the heat-resistant storage stability can be improved while improving the low-temperature fixability of the toner. From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner, the glass transition temperature of the polyester (B) contained in the shell portion is 3 ° C. or more higher than the glass transition temperature of the polyester (A) contained in the core portion, preferably Higher than 5 ° C, more preferably higher than 10 ° C, and still more preferably higher than 15 ° C.

  The softening point of the polyester (A) is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, further preferably 85 ° C. or higher, from the viewpoint of improving the heat resistant storage stability and document offset resistance of the toner. From the viewpoint of improving the low-temperature fixability, it is preferably 120 ° C. or lower, more preferably 110 ° C. or lower, and still more preferably 100 ° C. or lower.

  The softening point of the polyester (B) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, further preferably 100 ° C. or higher, from the viewpoint of improving the heat resistant storage stability and document offset resistance of the toner. Is 180 ° C. or lower, more preferably 150 ° C. or lower, and still more preferably 140 ° C. or lower.

  The acid values of the polyesters (A) and (B) are preferably independently from the viewpoint of improving the dispersion stability of the dispersion of resin particles containing the polyester in an aqueous medium at the time of toner production. 1 mgKOH / g or more, more preferably 10 mgKOH / g or more, further preferably 13 mgKOH / g or more, preferably 70 mgKOH / g or less, more preferably 50 mgKOH / g or less, and further preferably 30 mgKOH / g or less.

The number average molecular weights of the polyesters (A) and (B) are preferably independently 1,000 or more, more preferably from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Is 2,000 or more, preferably 6,000 or less, more preferably 5,000 or less, and still more preferably 4,000 or less. The number average molecular weight of the polyester is a value obtained by measuring the tetrahydrofuran-soluble content.
The glass transition temperature, softening point, acid value, and number average molecular weight of the polyester can be easily adjusted by adjusting the raw material monomer composition, the polymerization initiator, the molecular weight, the catalyst amount, etc., or by selecting the reaction conditions.

<Production method of polyester>
The polyester can be produced by subjecting an alcohol component and a carboxylic acid component to a polycondensation reaction. For example, the alcohol component and the carboxylic acid component in an inert gas atmosphere, if necessary, using an esterification catalyst, an esterification cocatalyst, a polymerization inhibitor, etc., preferably at a temperature of 120 ° C. or higher and 250 ° C. or lower. It can be produced by polycondensation with.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and di (2-ethylhexanoic acid) tin, and titanium compounds such as titanium diisopropylate bistriethanolamate.
Although there is no restriction | limiting in the usage-amount of an esterification catalyst, Preferably it is 0.01 mass part or more with respect to 100 mass parts of total amounts of an alcohol component and a carboxylic acid component, More preferably, it is 0.1 mass part or more. The amount is preferably 1 part by mass or less, more preferably 0.8 part by mass or less.

  Examples of the esterification promoter include gallic acid. The amount of the esterification cocatalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 100 parts by mass or more with respect to the total amount of the alcohol component and the carboxylic acid component. 0.5 parts by mass or less, more preferably 0.1 parts by mass or less.

  Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, and preferably 0 with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. 0.5 parts by mass or less, more preferably 0.1 parts by mass or less.

  In the present invention, the polyester includes not only an unmodified polyester as long as it has an acid group, but also a polyester modified to such an extent that the properties are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.

  Further, the electrophotographic toner of the present invention may contain a resin other than polyester, for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, and polyurethane, as long as the effects of the present invention are not impaired.

〔Release agent〕
The electrophotographic toner of the present invention preferably contains a release agent from the viewpoint of improving the releasability, low-temperature fixability and document offset resistance of the toner. The release agent may be contained in either the core part or the shell part, but it is more preferred that it be contained in at least the core part from the viewpoint of improving the heat resistant storage stability of the toner.
As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicone waxes; fatty acid amides such as oleic acid amide and stearic acid amide; plant waxes such as carnauba wax, rice wax and candelilla wax; beeswax etc. Animal waxes; mineral or petroleum waxes such as montan wax, paraffin wax, and Fischer-Tropsch wax; synthetic waxes such as ester wax. Among these, from the viewpoint of improving toner releasability, low-temperature fixability and document offset resistance, vegetable waxes and mineral or petroleum waxes are preferable, and carnauba wax and paraffin wax are more preferable.
These release agents can be used alone or in combination of two or more, and it is preferable to use in combination of two or more. From the viewpoint of improving the releasability, low-temperature fixability and document offset resistance of the toner, it is preferable to use a plant-based wax and a mineral-based or petroleum-based wax in combination, and to use a carnauba wax and a paraffin wax in combination. Further preferred.

The melting point of the release agent is preferably 60 ° C. or higher, more preferably 65 ° C. or higher, more preferably 70 ° C. or higher, from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Still more preferably, it is 73 degreeC or more, Preferably it is 100 degrees C or less, More preferably, it is 95 degrees C or less, More preferably, it is 90 degrees C or less, More preferably, it is 85 degrees C or less. When two or more types are used in combination, the melting point is preferably 60 ° C. or higher and 100 ° C. or lower from the viewpoint of improving the low-temperature fixability of the toner. That is, the release agent preferably contains at least two release agents having a melting point of 60 ° C. or more and 100 ° C. or less, and more preferably each melting point is 60 ° C. or more and 90 ° C. or less.
In the present invention, the melting point of the release agent is determined by the method described in the examples. When two or more release agents are used in combination, the melting point of the release agent is the melting point of the release agent having the largest mass ratio among the release agents contained in the obtained toner, and the melting point of the release agent in the present invention. And When all have the same ratio, the lowest value is set.

  The amount of the release agent used is preferably 1 part by mass or more, more preferably 100 parts by mass with respect to 100 parts by mass of the resin constituting the toner, from the viewpoint of improving toner releasability, low-temperature fixability and document offset resistance. 3 parts by mass or more, more preferably 5 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 10 parts by mass or less.

  The electrophotographic toner of the present invention may contain a colorant and a charge control agent as long as the effects of the present invention are not impaired. Moreover, you may contain additives, such as reinforcement fillers, such as a fibrous material, antioxidant, and anti-aging agent, as needed.

[Colorant]
The toner of the present invention may contain a colorant in either the core portion or the shell portion. However, from the viewpoint of improving the image density of the toner, the toner is preferably contained in the core portion. It is more preferable to have also.
The content in the case of containing a colorant is preferably 1 part by mass or more, more preferably 5 parts by mass or more, with respect to 100 parts by mass of the resin constituting the toner, from the viewpoint of improving the image density of the toner. , Preferably 20 parts by mass or less, more preferably 10 parts by mass or less.
Examples of the colorant used in the present invention include pigments and dyes, and pigments are preferable from the viewpoint of improving the toner image density.
Specific examples of the pigment include carbon black, inorganic composite oxide, benzidine yellow, brilliantamine 3B, brilliantamine 6B, bengal, aniline blue, ultramarine blue, copper phthalocyanine, phthalocyanine green, and the like. Phthalocyanine is preferred.
Specific examples of the dye include acridine dyes, azo dyes, benzoquinone dyes, azine dyes, anthraquinone dyes, indigo dyes, phthalocyanine dyes, aniline black dyes, and the like.
A coloring agent can be used individually by 1 type or in combination of 2 or more types.

[Charge control agent]
Examples of the charge control agent include a chromium-based azo dye, an iron-based azo dye, an aluminum azo dye, and a salicylic acid metal complex. From the viewpoint of improving the charging stability of the toner and the availability, a salicylic acid metal complex. Is preferred. Various charge control agents may be used alone or in combination of two or more.
The content in the case of containing a charge control agent is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the resin constituting the toner from the viewpoint of improving the charging stability of the toner and improving the image quality. Preferably it is 0.3 mass part or more, More preferably, it is 0.5 mass part or more, Preferably it is 10 mass parts or less, More preferably, it is 7 mass parts or less, More preferably, it is 5 mass parts or less.

[Method for producing toner for electrophotography]
The electrophotographic toner of the present invention is preferably produced by a production method including the following steps (1) to (3).
Step (1): Step of aggregating the resin particles (a) containing the polyester (A) to obtain aggregated particles (1) Step (2): Containing the polyester (B) in the aggregated particles (1) Step of obtaining aggregated particles (2) by adding resin particles (b) to be processed Step (3): Step of obtaining toner particles having a core-shell structure by fusing the aggregated particles (2) Further, the step (3) ) Is preferably followed by post-treatment steps such as washing and drying.
Hereinafter, each component, each process, etc. which are used for the said manufacturing method are demonstrated.

[Step (1)]
Step (1) is a step of obtaining aggregated particles (1) by aggregating resin particles (a) containing polyester (A).

[Resin particles (a)]
The resin particles (a) contain the polyester (A) described above.

  The content of the polyester (A) in the resin of the resin particles (a) is a resin constituting the resin particles (a) from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Among them, it is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, still more preferably substantially 100% by mass, and still more preferably 100% by mass.

In addition, the resin particles (a) may be particles composed only of a resin, but are obtained from a mixed resin containing a colorant from the viewpoint of sharpening the particle size distribution of the toner and obtaining a high-quality image. In other words, it preferably contains a colorant, and is preferably a colorant-containing resin particle containing a colorant.
When the resin particles (a) are colorant-containing resin particles, the content of the colorant is preferably based on 100 parts by mass of the resin constituting the resin particles (a) from the viewpoint of improving the image density of the toner. 1 mass part or more, More preferably, it is 5 mass parts or more, Preferably it is 20 mass parts or less, More preferably, it is 10 mass parts or less.

The resin particles (a) are preferably produced by a method in which the above-mentioned optional components such as the resin containing the polyester (A) and the colorant are dispersed in an aqueous medium to obtain a dispersion of the resin particles (a).
As the aqueous medium, those containing water as a main component are preferable. From the viewpoint of improving the dispersion stability of the resin particle dispersion and the environmental viewpoint, the content of water in the aqueous medium is preferably 80% by mass or more, More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more, More preferably, it is substantially 100 mass%, More preferably, it is 100 mass%. As water, deionized water or distilled water is preferably used.
Components other than water include alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having an alkyl group having 1 to 3 carbon atoms such as acetone and methyl ethyl ketone; and organic solvents that dissolve in water such as cyclic ethers such as tetrahydrofuran. Used. Among these, from the viewpoint of preventing the organic solvent from being mixed into the toner, an alkyl alcohol having 1 to 5 carbon atoms that does not dissolve the polyester is preferable, and methanol, ethanol, isopropanol, and butanol are more preferable.

  As a method for obtaining a dispersion of resin particles (a), a method of adding a resin or the like to an aqueous medium and performing a dispersion treatment with a disperser or the like, a method of gradually adding an aqueous medium to a resin or the like and performing phase inversion emulsification, etc. From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance, a method using phase inversion emulsification is preferred. As a method of phase inversion emulsification, first, polyester (A) and, if necessary, the above-mentioned optional components such as a surfactant and a colorant are melt-mixed to obtain a resin mixture, and then an aqueous medium is added to the resin mixture. It is preferable to add and invert the phase. Hereinafter, the method by the phase inversion emulsification will be described.

First, a resin containing the polyester (A) and the optional components such as a surfactant and a colorant are melted and mixed as necessary to obtain a resin mixture.
When a resin other than a plurality of types of polyesters (A) or polyesters (A) is included, a mixture of these polyesters (A) and other resins may be used in advance, but other optional components are added. At the same time, the resin mixture may be obtained by simultaneously adding, melting and mixing.
As a method for obtaining the resin mixture, for example, the resin containing the polyester (A), the surfactant, the basic aqueous solution, and the above-mentioned optional components such as the colorant are put in a container, and the resin is stirred while stirring with a stirrer. A method of melting and mixing uniformly is preferable.
The dispersion of the resin particles (a) in the present invention preferably contains a surfactant from the viewpoint of improving the dispersion stability of the resin particle dispersion.

Examples of the surfactant include nonionic surfactants, anionic surfactants, and cationic surfactants. From the viewpoint of improving the dispersion stability of the resin particle dispersion, nonionic surfactants are used. It is preferable to use a nonionic surfactant and an anionic surfactant or a cationic surfactant in combination, and it is more preferable to use a nonionic surfactant and an anionic surfactant in combination.
When a nonionic surfactant and an anionic surfactant are used in combination, the mass ratio of the nonionic surfactant to the anionic surfactant (nonionic surfactant / anionic surfactant) is: From the viewpoint of improving the dispersion stability of the resin particle dispersion, it is preferably 0.3 or more, more preferably 0.5 or more, and preferably 10 or less, more preferably 5 or less.

The nonionic surfactant includes at least one selected from the group consisting of polyoxyethylene alkyl aryl ethers, polyoxyethylene alkyl or alkenyl ethers, polyoxyethylene fatty acid esters, and oxyethylene / oxypropylene block copolymers. preferable.
Specific examples of polyoxyethylene alkyl aryl ethers include polyoxyethylene nonylphenyl ether, and specific examples of polyoxyethylene alkyl or alkenyl ethers include polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and the like. Is mentioned. Specific examples of the polyoxyethylene fatty acid esters include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate and the like.
As the nonionic surfactant, from the viewpoint of improving the dispersion stability of the resin particle dispersion, polyoxyethylene alkyl or alkenyl ethers are preferable, and polyoxyethylene lauryl ether is more preferable.

Examples of anionic surfactants include alkylbenzene sulfonates, alkyl sulfates, alkyl ether sulfates, polyoxyalkylene alkyl ether sulfates, etc., from the viewpoint of improving the dispersion stability of the resin particle dispersion. Alkyl benzene sulfonate and alkyl ether sulfate are preferable.
As the alkyl benzene sulfonate, an alkali metal salt of dodecyl benzene sulfonic acid is preferable, and sodium dodecyl benzene sulfonate is more preferable. As the alkyl sulfate, an alkali metal salt of dodecyl sulfate is preferable, and sodium dodecyl sulfate is more preferable. As the alkyl ether sulfate, an alkali metal salt of dodecyl ether sulfate is preferable, and sodium dodecyl ether sulfate is more preferable. As the polyoxyalkylene alkyl ether sulfate, polyoxyethylene lauryl ether sulfate is preferable.

  As an example of the cationic surfactant, a quaternary ammonium salt is preferable, and examples thereof include alkylbenzyldimethylammonium chloride and alkyltrimethylammonium chloride.

  From the viewpoint of improving the dispersion stability of the resin particle dispersion, the content of the surfactant is preferably 0.5 parts by mass or more, more preferably 100 parts by mass of the resin constituting the resin particles (a). 1 part by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass from the viewpoint of improving the heat resistant storage stability of the toner. It is not more than part by mass, more preferably not more than 10 parts by mass, still more preferably not more than 5 parts by mass.

Examples of the basic compound used in the basic aqueous solution include inorganic basic compounds and organic basic compounds.
Examples of inorganic base compounds include hydroxides, carbonates and bicarbonates of alkali metals such as potassium, sodium, and lithium, and ammonia, and hydroxides, carbonates, and bicarbonates of alkali metals. Specific examples include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Examples of the organic base compound include alkanolamines such as diethylethanolamine. From the viewpoints of improving the dispersion stability of the resin particle dispersion, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving document offset resistance, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate are used. Preferably, potassium hydroxide is more preferable.

  The concentration of the basic compound in the basic aqueous solution is preferably 1% by mass or more, more preferably 10% by mass or more, and further preferably 30% by mass from the viewpoint of improving the dispersion stability and productivity of the resin particle dispersion. Further, it is preferably 60% by mass or less, more preferably 55% by mass or less, and still more preferably 50% by mass or less.

The temperature at which the resin is melted and mixed is preferably equal to or higher than the glass transition temperature of the polyester (A) from the viewpoint of obtaining homogeneous resin particles. Specifically, it is preferably 75 ° C. or higher, more preferably 80 ° C. or higher, further preferably 85 ° C. or higher, and preferably less than 100 ° C., more preferably 98 ° C. or lower.
Further, the resin may be dissolved in an organic solvent. Thereby, uniform resin particles can be obtained at a lower temperature. Examples of the organic solvent include organic solvents that can be used in the dispersion of the resin particles (a) described above, preferably a dialkyl ketone having an alkyl group having 1 to 3 carbon atoms, and more preferably methyl ethyl ketone. .

(Phase inversion process)
Next, an aqueous medium is added to the resin mixture and phase inversion is performed to obtain a dispersion of resin particles (a).

The temperature at which the aqueous medium is added is selected from the viewpoints of improving the dispersion stability of the dispersion of resin particles, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving document offset resistance. It is preferably at least the glass transition temperature of the resin constituting a), and preferably below the boiling point of the aqueous medium used in step (1). Specifically, it is preferably 75 ° C. or higher, more preferably 80 ° C. or higher, further preferably 85 ° C. or higher, and preferably less than 100 ° C., more preferably 98 ° C. or lower.
From the viewpoint of improving the dispersion stability of the dispersion of resin particles and obtaining resin particles having a small particle size, the addition rate of the aqueous medium is the resin 100 constituting the resin particles (a) until the phase inversion is completed. The amount is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 50 parts by mass or less, and more preferably 30 parts by mass / min with respect to parts by mass. Hereinafter, it is more preferably 10 parts by mass / min or less, and still more preferably 5 parts by mass / min or less. There is no restriction | limiting in the addition speed | rate of the aqueous medium after the resin phase is obtained after phase inversion.
The amount of the aqueous medium used is preferably 100 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (a) from the viewpoint of improving the productivity of the toner and obtaining uniform aggregated particles in the subsequent aggregation process. Part or more, more preferably 150 parts by weight or more, still more preferably 170 parts by weight or more, and preferably 900 parts by weight or less, more preferably 500 parts by weight or less, still more preferably 300 parts by weight or less.

  From the viewpoint of stabilizing the core-shell structure and improving the low-temperature fixability and heat-resistant storage stability of the toner, after adding an aqueous medium to the resin mixture and performing phase inversion, a cross-linking agent such as a compound having an oxazoline group is mixed to obtain resin particles ( You may bridge | crosslink the polyester resin which comprises a).

  The solid content concentration of the resulting dispersion of the resin particles (a) is preferably from the viewpoint of improving the productivity of the toner, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving the document offset resistance. 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, still more preferably 25% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, Preferably it is 35 mass% or less. In addition, solid content is the total amount of non-volatile components, such as resin and surfactant.

The volume median particle size of the resin particles (a) in the dispersion of the resin particles (a) is preferably from the viewpoint of achieving both low temperature fixability and heat resistant storage stability of the toner and improving document offset resistance. It is 02 μm or more, more preferably 0.05 μm or more, further preferably 0.08 μm or more, preferably 0.5 μm or less, more preferably 0.4 μm or less, and further preferably 0.3 μm or less. Here, the volume-median particle diameter is a particle diameter at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle diameter, and is obtained by the method described in the examples.
The coefficient of variation (CV value) (%) of the particle size distribution of the resin particles (a) is preferably 40% from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Below, more preferably 35% or less, still more preferably 30% or less, and further preferably 25% or less. Further, from the viewpoint of improving the productivity of the dispersion of the resin particles (a), it is preferably 5% or more, more preferably 10% or more, and further preferably 15% or more. The CV value is a value represented by the following formula, and is determined by the method described in the examples.
CV value (%) = [standard deviation of particle size distribution (μm) / volume average particle size (μm)] × 100

[Release agent particles]
As described above, the electrophotographic toner of the present invention preferably contains a release agent, and more preferably at least in the core portion. Therefore, in the step (1), the release agent particles may be aggregated together with the resin particles (a) to obtain aggregated particles (1). The release agent particles are preferably obtained as a dispersion of release agent particles by dispersing the release agent in an aqueous medium.

The dispersion of the release agent particles is preferably obtained by dispersing the release agent and the aqueous medium using a disperser in the presence of a surfactant at a temperature equal to or higher than the melting point of the release agent. As the disperser to be used, a homogenizer, an ultrasonic disperser and the like are preferable from the viewpoint of improving the low-temperature fixability and heat-resistant storage stability of the toner.
Examples of the ultrasonic disperser include an ultrasonic homogenizer, and commercially available apparatuses include “US-150T”, “US-300T”, “US-600T” (manufactured by Nippon Seiki Seisakusho), “SONIFIER”. 4020-400 "," SONIFIER 4020-800 "(manufactured by Branson) and the like.
Further, before using the disperser, it is preferable to preliminarily disperse the mold release agent, optionally the surfactant, and the aqueous medium in advance using a mixer such as a homomixer or a ball mill.
As the aqueous medium, those used when obtaining the resin particles (a) are preferably used.

The dispersion of the release agent particles in the aqueous medium may be performed in the presence of a surfactant from the viewpoint of improving the dispersion stability of the release agent particles and obtaining uniform aggregated particles in the subsequent aggregation step. Good.
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants and the like, and the same ones used for the production of the resin particles (a) can be used. From the viewpoint of improving the cohesiveness between the release agent particles and the resin particles, an anionic surfactant is preferable. Among them, from the same viewpoint, a hydrophilic group is more preferably a carboxy group, and a polycarboxylate is further preferable. .
Examples of polycarboxylates include polyacrylates, salts of acrylic acid-maleic acid copolymers, polymaleates from the viewpoint of improving the cohesiveness of release agent particles during toner preparation and preventing release. Etc., and a salt of acrylic acid-maleic acid copolymer is more preferable. As the salt, an alkali metal salt is preferable, and a sodium salt is more preferable.
The weight average molecular weight of the polycarboxylate is preferably 90,000 or less, more preferably 50,000 or less, and preferably 3,000 or more, from the viewpoint of improving the dispersion stability of the release agent particles. More preferably, it is 10,000 or more.
Commercially available products of polycarboxylates include “Poise 530” (sodium polyacrylate aqueous solution, weight average molecular weight 38000, effective concentration 40% by mass) and “Poise 521” (sodium acrylate-sodium maleate) manufactured by Kao Corporation. Polymer aqueous solution, weight average molecular weight 20000, effective concentration 40% by mass) and the like.

  The content of the surfactant in the release agent dispersion is from the viewpoint of improving the dispersion stability of the release agent particles, improving the cohesiveness of the release agent particles at the time of toner preparation, and preventing release. Preferably it is 0.05 mass% or more, More preferably, it is 0.1 mass% or more, More preferably, it is 0.4 mass% or more, Preferably it is 5 mass% or less, More preferably, it is 2 mass% or less, More preferably Is 1% by mass or less. From the same viewpoint, the content of the surfactant in the release agent dispersion is preferably 0.2 parts by mass or more, more preferably 1.0 parts by mass with respect to 100 parts by mass of the total release agent. As mentioned above, More preferably, it is 2.0 mass parts or more, Preferably it is 15 mass parts or less, More preferably, it is 10 mass parts or less, More preferably, it is 5.0 mass parts or less.

  The solid content concentration of the release agent particle dispersion is preferably 7% by mass or more, more preferably 10% by mass or more from the viewpoint of improving the productivity of the toner and improving the dispersion stability of the release agent particles. In addition, it is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. In addition, solid content is the total amount of non-volatile components, such as a mold release agent and surfactant.

  The volume-median particle size of the release agent particles is preferably from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation process, from the viewpoint of improving the low-temperature fixability and heat-resistant storage stability of the toner, and improving document offset resistance. It is 0.10 μm or more, more preferably 0.20 μm or more, further preferably 0.30 μm or more, preferably 1.0 μm or less, more preferably 0.80 μm or less, and further preferably 0.60 μm or less.

  The CV value of the release agent particles is preferably 50% or less, more preferably 40% or less, and still more preferably 35 from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation step and improving the charging stability of the toner. % Or less. Further, from the viewpoint of improving the productivity of the release agent particle dispersion, it is preferably 5% or more, more preferably 10% or more, and further preferably 15% or more. The volume median particle size and CV value of the release agent particles are determined by the same method as that for the resin particles (a), and specifically by the method described in the examples.

[Production of Aggregated Particles (1)]
The agglomerated particles (1) agglomerate an optional component such as a dispersion of the resin particles (a) and, if necessary, an aggregating agent, a releasing agent particle dispersion, a surfactant, and a colorant in an aqueous medium. Thus, it can be suitably produced by a method for obtaining aggregated particles.
In this step, first, it is preferable to obtain a mixed dispersion by mixing the dispersion of resin particles (a) and the dispersion of release agent particles in an aqueous medium.
In addition, when a colorant is not mixed in the resin particles (a), it is preferable to mix a colorant in the mixed dispersion.
Further, resin particles other than the resin particles (a) may be mixed in the mixed dispersion.
There is no restriction | limiting in order of mixing, You may add any in order and may add simultaneously.

From the viewpoint of improving the document offset resistance, the content of the resin particles (a) in the mixed dispersion liquid containing the resin particles (a) and the release agent particles makes the low-temperature fixability and heat-resistant storage stability of the toner compatible. Preferably, it is 5% by mass or more, more preferably 10% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, from the viewpoint of controlling aggregation and obtaining aggregated particles having a desired particle size. It is.
In the mixed dispersion containing the resin particles (a) and the release agent particles, the content of the aqueous medium is from the viewpoint of improving the productivity of the toner and from the viewpoint of obtaining aggregation particles having a desired particle size by controlling aggregation. Preferably it is 55 mass% or more, More preferably, it is 60 mass% or more, Preferably it is 90 mass% or less, More preferably, it is 85 mass% or less.
From the viewpoint of improving the releasability of the toner, the low-temperature fixability and heat-resistant storage stability of the toner, and improving the document offset resistance, the release agent particles are used with respect to 100 parts by mass of the resin particles (a). The amount is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less.
The mixing temperature is preferably 0 ° C. or higher and 40 ° C. or lower from the viewpoint of controlling aggregation and obtaining aggregated particles having a desired particle size.

Next, the particles in the mixed dispersion are aggregated to obtain a dispersion of aggregated particles (1). It is preferable to add a flocculant for efficient aggregation.
The flocculant is preferably an electrolyte, and more preferably a salt, from the viewpoint of obtaining a toner having a desired particle diameter while preventing excessive aggregation.

Examples of the aggregating agent include a quaternary salt cationic surfactant, an organic aggregating agent such as polyethyleneimine; an inorganic aggregating agent such as an inorganic metal salt, an inorganic ammonium salt, and a bivalent or higher metal complex. From the viewpoint of improving cohesion and obtaining uniform aggregated particles, inorganic coagulants are preferred, inorganic metal salts and inorganic ammonium salts are more preferred, and inorganic ammonium salts are even more preferred.
The valence of the cation of the inorganic flocculant is preferably from 1 to 5 and more preferably from 1 to 2 and more preferably from the viewpoint of obtaining a toner having a desired particle size while preventing excessive aggregation. Is monovalent.
Examples of the monovalent cation of the inorganic flocculant include sodium, potassium, and ammonium. Ammonium is preferable from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance.
Examples of the inorganic metal salt include metal salts such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride, magnesium sulfate, and calcium nitrate, and inorganic metal salt polymers such as polyaluminum chloride and polyaluminum hydroxide. Examples of inorganic ammonium salts include ammonium sulfate, ammonium chloride, and ammonium nitrate. The flocculant is preferably an inorganic ammonium salt and more preferably ammonium sulfate from the viewpoint of improving the flocculence and obtaining uniform agglomerated particles.
The amount of the aggregating agent used is preferably 50 masses with respect to 100 mass parts of the resin constituting the resin particles (a) from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Part or less, more preferably 40 parts by weight or less, still more preferably 35 parts by weight or less. Further, from the viewpoint of controlling the aggregation of the resin particles to obtain aggregated particles having a desired particle diameter, the amount is preferably 1 part by mass or more, more preferably 10 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (a). Part or more, more preferably 20 parts by weight or more.

As an aggregating method, an aggregating agent is preferably added dropwise as an aqueous solution to a container containing a mixed dispersion. The flocculant may be added at one time, or may be added intermittently or continuously. However, it is preferable to perform sufficient stirring at the time of addition and after completion of the addition. The concentration of the aqueous solution of the flocculant is preferably 2% by mass or more, more preferably 4% by mass or more, and preferably 40% by mass or less from the viewpoint of controlling aggregation and obtaining aggregated particles having a desired particle size. More preferably, it is 30 mass% or less, More preferably, it is 20 mass% or less, More preferably, it is 10 mass% or less.
The dropping time of the aggregating agent is preferably 1 minute or more, more preferably 5 minutes or more from the viewpoint of controlling aggregation and obtaining aggregated particles having a desired particle diameter, and from the viewpoint of improving toner productivity. , Preferably 120 minutes or less, more preferably 60 minutes or less.
The temperature at which the flocculant is dropped is preferably 0 ° C. or higher, more preferably 10 ° C. or higher from the viewpoint of improving the productivity of the toner. From the viewpoint of obtaining, it is preferably 70 ° C. or lower, more preferably 60 ° C. or lower, and further preferably 50 ° C. or lower.

Furthermore, it is preferable to raise the temperature of the dispersion liquid after or while adding the flocculant from the viewpoint of promoting aggregation and controlling the particle size of the aggregated particles to suppress the formation of coarse particles. As temperature to maintain, 50 to 70 degreeC is preferable. It is preferable to confirm the progress of aggregation by monitoring the volume-median particle size of the aggregated particles in the temperature range. The volume median particle size is measured by the method described in the examples.
The volume-median particle size of the obtained aggregated particles (1) is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Preferably it is 3 micrometers or more, Preferably it is 10 micrometers or less, More preferably, it is 8 micrometers or less, More preferably, it is 6 micrometers or less. The volume-median particle size of the aggregated particles (1) is specifically determined by the method described in the examples.

[Step (2)]
Step (2) is a step of obtaining aggregated particles (2) by adding resin particles (b) containing polyester (B) to aggregated particles (1) obtained in step (1).
In this step, the dispersion of resin particles (b) is added to the dispersion of aggregated particles (1) obtained in step (1), and the resin particles (b) are further adhered to the aggregated particles (1). It is preferable to obtain a dispersion of aggregated particles (2).

[Resin particles (b)]
The resin particles (b) contain the polyester (B) described above.

  The content of the polyester (B) in the resin of the resin particles (b) is a resin constituting the resin particles (b) from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Among them, it is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, still more preferably substantially 100% by mass, and still more preferably 100% by mass.

The resin particles (b) are preferably produced by a method in which the above-mentioned optional components such as the resin containing the polyester (B) and the colorant are dispersed in an aqueous medium to obtain a dispersion containing the resin particles (b). .
A preferred embodiment of a method for obtaining a dispersion containing resin particles (b) is the same as the method for obtaining a dispersion containing resin particles (a).

  The solid content concentration of the resulting dispersion of the resin particles (b) is preferably from the viewpoint of improving the productivity of the toner, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving the document offset resistance. It is 10 mass% or more, More preferably, it is 15 mass% or more, More preferably, it is 20 mass% or more. Further, it is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 35% by mass or less. In addition, solid content is the total amount of non-volatile components, such as resin and surfactant.

  The volume median particle size of the resin particles (b) in the dispersion of the resin particles (b) is preferably from the viewpoint of achieving both low temperature fixability and heat resistant storage stability of the toner and improving document offset resistance. It is 02 μm or more, more preferably 0.05 μm or more, further preferably 0.07 μm or more, preferably 1.5 μm or less, more preferably 1 μm or less, still more preferably 0.5 μm or less, and still more preferably 0.00. 2 μm or less.

  In addition, the coefficient of variation (CV value) (%) of the particle size distribution of the resin particles (b) is compatible with both low temperature fixability and heat resistant storage stability of the toner from the viewpoint of improving toner productivity, and document offset resistance. From the viewpoint of improvement, it is preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, and still more preferably 28% or less. Further, from the viewpoint of improving the productivity of the dispersion liquid of the resin particles (b), it is preferably 5% or more, more preferably 10% or more, and further preferably 15% or more. Specifically, the volume median particle size and CV value of the resin particles (b) are determined by the method described in the examples.

Further, the resin particles (b) may be particles composed only of a resin, but from the viewpoint of improving the image density of the obtained toner, it is preferable that the resin particles (b) contain a colorant in the same manner as the resin particles (a). A colorant-containing resin particle containing a colorant is preferable. It is more preferable that the resin particles (a) and (b) are both colorant-containing resin particles.
When the resin particles (b) are colorant-containing resin particles, the content of the colorant is preferably based on 100 parts by mass of the resin constituting the resin particles (b) from the viewpoint of improving the image density of the toner. 1 mass part or more, More preferably, it is 5 mass parts or more, Preferably it is 20 mass parts or less, More preferably, it is 10 mass parts or less.

[Production of Aggregated Particles (2)]
In this step, the dispersion of resin particles (b) is added to the dispersion of aggregated particles (1) obtained in step (1), and the resin particles (b) are further adhered to the aggregated particles (1). It is preferable to obtain a dispersion of aggregated particles (2).

  Before adding the dispersion of resin particles (b) to the dispersion of aggregated particles (1), an aqueous medium may be added to the dispersion of aggregated particles (1) for dilution. Further, when the dispersion of resin particles (b) is added to the dispersion of aggregated particles (1), the aggregating agent is added to the aggregated particles (1) in order to efficiently adhere the resin particles (b) to the aggregated particles (1). May be used.

  As a preferable addition method in the case of adding the dispersion liquid of the resin particles (b) to the dispersion liquid of the aggregated particles (1), a method of simultaneously adding the aggregation liquid and the dispersion liquid of the resin particles (b), the aggregation agent and the resin Examples thereof include a method of alternately adding a dispersion of particles (b) and a method of adding a dispersion of resin particles (b) while gradually raising the temperature of the dispersion of aggregated particles (1). By doing in this way, the cohesiveness fall of the coagulated particle (1) and the resin particle (b) by the coagulant | flocculant density | concentration fall can be prevented. From the viewpoint of improving the productivity of the toner and simplifying the production, it is preferable to add the dispersion of the resin particles (b) while gradually increasing the temperature of the dispersion of the aggregated particles (1).

  The temperature in the system in this step is not more than 10 ° C. higher than the glass transition temperature of the polyester (B) from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. The temperature is preferably 5 ° C. or less higher than the glass transition temperature. When the aggregated particles (2) are produced in this temperature range, the low-temperature fixability and heat-resistant storage stability of the obtained toner are improved. Although the reason is not certain, it is considered that the generation of coarse particles is suppressed because fusion of the aggregated particles (2) does not occur.

The addition amount of the resin particles (b) is a mass ratio (resin) of the resin particles (b) and the resin particles (a) from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Particle (b) / resin particle (a)) is preferably 0.05 or more, more preferably 0.1 or more, still more preferably 0.15 or more, still more preferably 0.2 or more, and preferably Is 0.8 or less, more preferably 0.7 or less, still more preferably 0.6 or less, and still more preferably 0.5 or less.
By adding a small amount of the resin particles (b) compared to the resin particles (a), the effect of the core portion of the toner of the present invention can be sufficiently exhibited, and the heat resistant storage stability can be improved.

  The resin particle (b) dispersion may be added continuously over a certain period of time, may be added at a time, or may be added in a plurality of divided portions. It is preferable to add them continuously or in several divided portions. By adding as described above, the resin particles (b) are likely to selectively adhere to the aggregated particles (1). Among these, from the viewpoint of promoting selective adhesion and improving the productivity of toner, it is preferable to add continuously over a certain period of time. The time for continuous addition is preferably 1 hour or more, more preferably 2 hours or more, from the viewpoint of obtaining uniform aggregated particles (2) and improving the productivity of the toner, and preferably 10 hours or less, more preferably 7 hours or less.

The total amount of the resin particles (b) may be added, and aggregation may be stopped when the toner particles have grown to an appropriate particle size.
The particle diameter for stopping aggregation, that is, the particle diameter of the aggregated particles (2) is preferably a volume-median particle diameter from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. Is 1 μm or more, more preferably 2 μm or more, further preferably 3 μm or more, further preferably 4 μm or more, and preferably 10 μm or less, more preferably 9 μm or less, still more preferably 8 μm or less, and even more preferably 6 μm or less. .

  The degree of circularity of the agglomerated particles (2) is preferably 0.910 or more, more preferably 0.915 or more, from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. From the same viewpoint, it is preferably 0.950 or less, more preferably 0.945 or less, and still more preferably 0.940 or less.

Examples of the method for stopping the aggregation include a method of cooling the dispersion, a method of adding an aggregation stopper, and a method of diluting the dispersion. From the viewpoint of reliably preventing unnecessary aggregation, the aggregation stopper A method of stopping the aggregation by adding is preferable.
As the aggregation terminator, a surfactant is preferable, and an anionic surfactant is more preferable. Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl sulfate, alkyl ether sulfate, polyoxyalkylene alkyl ether sulfate, and the like, preferably polyoxyalkylene alkyl ether sulfate, more preferably polyoxyalkylene alkyl ether sulfate. Oxyethylene lauryl ether sulfate.
The aggregation terminator can be used alone or in combination of two or more.
The addition amount of the aggregation terminator is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, with respect to 100 parts by mass of the total amount of the resin in the toner, from the viewpoint of surely preventing unnecessary aggregation. More preferably, it is 2 parts by mass or more. Further, from the viewpoint of reducing residual toner, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 8 parts by mass or less. The aggregation terminator is preferably added as an aqueous solution from the viewpoint of improving toner productivity.
The temperature at which the aggregation terminator is added is preferably the same as the temperature at which the aggregated particle dispersion is retained, and more preferably 50 ° C. or higher and 75 ° C. or lower, from the viewpoint of improving the productivity of the toner.

[Step (3)]
Step (3) is a step of fusing the agglomerated particles (2) obtained in step (2) to obtain toner particles having a core-shell structure. The agglomerated particles (2) are mainly physically connected to each other. The particles that are in a state of adhering to each other are fused and united to form core-shell particles.

From the viewpoint of improving the fusibility of the aggregated particles, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving document offset resistance, this step is preferably at least the glass transition temperature of the polyester (B). More preferably, it is held at a temperature of 3 ° C. higher than its glass transition temperature, more preferably 5 ° C. higher than its glass transition temperature. Further, from the viewpoint of maintaining the core-shell state of the toner and preventing the release agent from being released, in this step, the temperature is preferably 30 ° C. or lower, more preferably from the glass transition temperature of the polyester (B). The temperature is maintained at a temperature not higher than 25 ° C., more preferably not higher than 20 ° C. higher than the glass transition temperature.
The holding time in this step is preferably 1 minute or more, more preferably from the viewpoint of improving the fusing property of the aggregated particles, achieving both low-temperature fixability and heat-resistant storage stability of the toner, and improving document offset resistance. It is 5 minutes or more, more preferably 10 minutes or more, preferably 6 hours or less, more preferably 5 hours or less, still more preferably 3 hours or less, and even more preferably 2 hours or less.

The volume median particle size of the toner particles obtained in this step is preferably at least 2 μm, more preferably at least 3 μm, and more preferably at least 3 μm from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner and improving document offset resistance. The thickness is preferably 4 μm or more, preferably 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less, and still more preferably 6 μm or less.
The average particle size of the fused toner particles obtained in this step is preferably not more than the average particle size of the aggregated particles (2). That is, in this step, it is preferable that the toner particles do not aggregate and fuse.

[Post-processing process]
In the present invention, a post-treatment step may be performed after the step (3), and it is preferable to isolate the toner particles obtained in the step (3).
Since the toner particles obtained in the step (3) are present in an aqueous medium, it is preferable to first perform solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used.
It is preferable to perform washing after the solid-liquid separation. When a nonionic surfactant is used in the production of the resin particles (a) and (b), it is preferable to remove the added nonionic surfactant, so the cloud point of the nonionic surfactant In the following, it is preferable to wash with an aqueous medium. The washing is preferably performed a plurality of times.
Next, it is preferable to perform drying. As a drying method, it is preferable to use a vacuum low temperature drying method, a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like. The moisture content of the toner particles after drying is preferably adjusted to 1.5% by mass or less, more preferably 1.0% by mass or less.

(toner)
The toner particles obtained by drying or the like can be used as they are as the toner of the present invention, but it is preferable to use toner particles whose surface has been treated as described below as the toner for electrophotography.
[Physical properties of toner]
The volume median particle size of the toner is preferably 2 μm or more, more preferably 3 μm or more, and further preferably 4 μm or more, from the viewpoint of obtaining a high-quality image and improving the toner productivity. It is 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less, and even more preferably 6 μm or less.
The coefficient of variation (CV value) in the particle size distribution of the toner is preferably 35% or less, more preferably 30% or less, and even more preferably 28% or less, from the viewpoint of obtaining a high-quality image. Further, from the viewpoint of improving the productivity of the toner, it is preferably 5% or more, more preferably 10% or more, and further preferably 15% or more.
The volume median particle size and CV value of the toner are determined by the method described in the examples.

The circularity of the toner is preferably 0.965 or more, and more preferably 0.970 or more, from the viewpoint of obtaining a toner having excellent transferability during printing. Further, the circularity of the toner is preferably 0.990 or less, and more preferably 0.985 or less, by the method described in Examples.
The electrophotographic toner of the present invention can be used as a one-component developer or a two-component developer mixed with a carrier.

(External additive)
In the electrophotographic toner of the present invention, the toner particles containing the above components can be used as the toner as they are, but it is possible to use the toner particles that have been treated by adding a fluidizing agent or the like as an external additive to the toner particle surface. preferable.
Examples of the external additive include hydrophobic silica, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, inorganic fine particles such as carbon black, and polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Among these, hydrophobic Silica is preferred. One type of external additive may be used alone, or two or more types may be used in combination.
When the surface treatment of the toner particles is performed using an external additive, the amount of the external additive added is preferably 1 part by mass or more, more preferably 2 parts, relative to 100 parts by mass of the toner particles before the treatment with the external additive. It is at least 5 parts by mass, preferably at most 5 parts by mass, more preferably at most 4 parts by mass.

  Each property value of polyester, resin particles, toner, etc. was measured and evaluated by the following method.

[Softening point of polyester and toner]
Using a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, and a load of 1.96 MPa was applied by a plunger, and the diameter was 1 mm and the length was 1 mm. Extruded from the nozzle. The amount of plunger drop of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.

[Glass transition temperature of polyester]
Using a differential scanning calorimeter “Q100” (manufactured by TA Instruments Japan), the sample was heated to 200 ° C. and cooled to 0 ° C. at a temperature decrease rate of 10 ° C./min. Measurement was performed at 10 ° C./min. Of the endothermic peaks observed, the peak temperature having the maximum peak area was defined as the maximum endothermic peak temperature. The intersection temperature between the extension line of the baseline below the maximum peak temperature of endotherm and the tangent showing the maximum slope from the peak rising portion to the peak apex was defined as the glass transition temperature.

[Weight average molecular weight and number average molecular weight of polyester]
The molecular weight distribution was measured by gel permeation chromatography (GPC) method, and the weight average molecular weight and number average molecular weight were calculated.

(1) Preparation of sample solution Polyester was dissolved in tetrahydrofuran at 25 ° C so that the concentration was 0.5 g / 100 ml. Subsequently, this solution was filtered using a fluororesin filter “DISMIC-25JP” (manufactured by ADVANTEC) having a pore size of 0.2 μm to remove insoluble components to obtain a sample solution.

(2) Measurement of molecular weight distribution Using the following measuring device and analytical column, tetrahydrofuran was flowed as an eluent at a flow rate of 1 ml / min, and the column was stabilized in a constant temperature bath at 40 ° C. Measurement was performed by injecting 100 μl of the sample solution. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. At this time, several types of monodisperse polystyrene (A-500 (weight average molecular weight Mw 5.0 × 10 ² ), A-1000 (Mw 1.01 × 10 ³ ), A-2500 (Mw 2.63 × 10 ³ ), A-5000 (Mw 5.97 × 10 ³ ), F-1 (Mw 1.02 × 10 ⁴ ), F-2 (Mw 1.81 × 10 ⁴ ), F-4 (Mw 3.97 × 10 ⁴ ), F- 10 (Mw 9.64 × 10 ⁴ ), F-20 (Mw 1.90 × 10 ⁵ ), F-40 (Mw 4.27 × 10 ⁵ ), F-80 (Mw 7.06 × 10 ⁵ ), F-128 (Mw 1.09 × 10 ⁶ )) was used as a standard sample.
Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation)
Analytical column: GMHXL + G3000HXL (both manufactured by Tosoh Corporation)

[Melting point of release agent]
Using a differential scanning calorimeter “Q100” (manufactured by TA Instruments Japan), the temperature was raised to 200 ° C., and the sample was cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min from that temperature. Measurement was made at 10 ° C./min, and the maximum peak temperature of heat of fusion was taken as the melting point.

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution (CV Value) of Resin Particles and Release Agent Particles]
(1) Measuring apparatus: Laser diffraction particle size measuring instrument “LA-920” (manufactured by Horiba, Ltd.)
(2) Measurement conditions: Distilled water was added to the measurement cell, and the volume-median particle size (D ₅₀ ) and the volume average particle size were measured at a concentration at which the absorbance was in an appropriate range. The CV value was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume average particle size) × 100

[Solid content concentration of resin particle dispersion and release agent particle dispersion]
Using an infrared moisture meter “FD-230” (manufactured by Kett Science Laboratory), 5 g of a measurement sample was dried at a temperature of 150 ° C. and in a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%). Moisture (mass%) was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (% by mass) = 100-water content (% by mass)

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution (CV Value) of Aggregated Particles (1) and (2)]
The volume median particle size (D ₅₀ ) of the particles was measured as follows.
Measuring instrument: Coulter Multisizer III (Beckman Coulter, Inc.)
・ Aperture diameter: 50μm
・ Analysis software: Multisizer III version 3.51 (Beckman Coulter, Inc.)
・ Electrolyte: Isoton II (Beckman Coulter)
Measurement conditions: 30,000 particles are measured after adjusting the particle size of 30,000 particles to a concentration that can be measured in 20 seconds by adding a sample dispersion containing aggregated particles to 100 mL of the electrolyte. From the particle size distribution, the volume median particle size (D ₅₀ ) and the volume average particle size were determined.
The CV value (%) was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume average particle size) × 100

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution (CV Value) of Toner and Toner Particles (Fused Particles)]
The volume median particle size of the toner and toner particles (fused particles) was measured as follows.
The measuring instrument, aperture diameter, analysis software, and electrolyte solution were the same as the volume median particle diameter of the aggregated particles.

Dispersion: Polyoxyethylene lauryl ether “Emulgen 109P” (manufactured by Kao Corporation, HLB: 13.6) was dissolved in the electrolytic solution to obtain a dispersion having a concentration of 5% by mass.
-Dispersion condition: 10 mg of a toner particle measurement sample is added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 mL of electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. To prepare a sample dispersion.
Measurement conditions: After adding the sample dispersion to 100 mL of the electrolyte solution, the particle size of 30,000 particles is adjusted to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured. The volume-median particle size (D ₅₀ ) and the volume average particle size were determined from the distribution.

The CV value (%) was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume average particle size) × 100

[Agglomerated particles (2) and circularity of toner]
-Preparation of dispersion: Regarding the aggregated particles (2), a dispersion of aggregated particles (2) was prepared by diluting with deionized water so that the solid content concentration was 0.001 to 0.05 mass%. As a toner dispersion, 50 mg of toner is added to 5 ml of a 5% by mass aqueous solution of polyoxyethylene lauryl ether “Emulgen 109P” (manufactured by Kao Corporation, HLB: 13.6) and dispersed for 1 minute by an ultrasonic disperser. After that, 20 ml of distilled water was added and further dispersed with an ultrasonic disperser for 1 minute to prepare a toner dispersion.
Measurement device: Flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation)
・ Measurement mode: HPF measurement mode

[Low-temperature fixability of toner]
Using a commercially available printer “Microline 5400” (Oki Data Co., Ltd.) on high quality paper “J paper A4 size” (Fuji Xerox Co., Ltd.), the toner adhesion amount on the paper is 0.42 to 0.48 mg / cm ^2. The solid image was output without fixing at a length of 50 mm, leaving a margin of 5 mm from the top edge of the A4 paper.
Next, the same printer with a variable temperature fixing device was prepared, the fixing device temperature was set to 90 ° C., and fixing was performed at a speed of 1.2 seconds per sheet in the A4 longitudinal direction to obtain a printed matter.
In the same manner, the temperature of the fixing device was increased by 5 ° C., and the fixing was performed to obtain a printed matter.

In a margin at the upper end of the printed image, a mending tape “Scotch Mending Tape 810” (manufactured by 3M, width 18 mm) cut to a length of 50 mm is lightly affixed, and then a 500 g weight is placed on it. One reciprocal pressing was performed at a speed of 10 mm / sec. Thereafter, the affixed tape was peeled off from the lower end side at a peeling angle of 180 degrees and a speed of 10 mm / sec to obtain a printed matter after the tape was peeled off. 30 high-quality paper “Excellent White Paper A4 Size” (manufactured by Oki Data Co., Ltd.) is laid under the printed matter before and after the tape is applied, and the reflected image density of the fixed image portion before and after the tape is applied to each printed matter. Measurement was carried out using a colorimeter “SpectroEye” (manufactured by GretagMacbeth, Inc., light emission conditions: standard light source D ₅₀ , observation field of view 2 °, density standard DINNB, absolute white standard), and the fixing ratio was calculated by the following formula.
Fixing rate (%) = (Reflected image density after peeling tape / Reflected image density before applying tape) × 100
The temperature at which the fixing rate was 90% or more was defined as the minimum fixing temperature. The lower the minimum fixing temperature, the better the low-temperature fixing property.

[Heat resistant storage stability of toner]
20 g of toner was put in a wide-mouthed polybin having an internal volume of 100 ml, sealed, and allowed to stand for 48 hours in an environment of any temperature. Thereafter, it was allowed to stand for 12 hours or more while being sealed at a temperature of 25 ° C. and cooled. Next, a “powder tester” (manufactured by Hosokawa Micron Corporation) was set on a sieve with an opening of 250 μm, and 20 g of the toner was placed on it and vibrated for 30 seconds. When no toner remained on the sieve, The maximum value of the arbitrary temperature was defined as the heat resistant storage temperature. The higher the temperature, the better the heat resistant storage stability of the toner.

[Toner anti-document offset temperature]
Using a commercially available printer “Microline 5400” (Oki Data Co., Ltd.) on high quality paper “J paper A4 size” (Fuji Xerox Co., Ltd.), the toner adhesion amount on the paper is 0.42 to 0.48 mg / cm ^2. A solid image was printed with a length of 50 mm. The printed images were superimposed and allowed to stand for 48 hours in an environment of an arbitrary temperature. Thereafter, a weight of 500 g was placed at a temperature of 25 ° C., and the load was applied by reciprocating at a speed of 10 mm / sec. The maximum temperature at which the toner did not adhere was defined as the document offset temperature. The higher the temperature, the better the toner resistance to document offset.

Production Examples 1-16
(Production of amorphous polyesters A1 to A6, B1 to B10)
Table 1 and Table 2, and the raw material monomer of polyester, terephthalic acid, di (2-ethylhexanoic acid) tin (II) salt and gallic acid, nitrogen introduction tube, dehydration tube, stirrer and thermocouple Place in an equipped 10 liter four-necked flask and incubate at 235 ° C. for 1 hour in a nitrogen atmosphere, then cool to 180 ° C. and add an acid component other than polyester raw material terephthalic acid. The temperature was raised at 0 ° C./hour, and then the reaction was carried out at 10 kPa to the desired softening point to obtain an amorphous polyester. The physical properties are shown in Table 1 and Table 2.

Production Example 17
(Production of resin particle dispersion a-1)
In a flask equipped with a stirrer, amorphous polyester A1 600 g, copper phthalocyanine pigment “ECB301” (manufactured by Dainichi Seika Kogyo Co., Ltd.) 45 g, polyoxyethylene lauryl ether “Emulgen 150” (nonionic surfactant, Kao Corporation) 6 g, 15 mass% sodium dodecylbenzenesulfonate aqueous solution “Neopelex G-15” (anionic surfactant, manufactured by Kao Co., Ltd.) 40 g, 48 mass% potassium hydroxide aqueous solution 20 g were added and stirred at 98 ° C. The mixture was melted by heating to 98 ° C. for 2 hours to obtain a resin mixture.
Next, while stirring, 1088 g of deionized water was added dropwise at 98 ° C. at a rate of 6 g / min to obtain an emulsion. Next, the obtained emulsion was cooled to 25 ° C., and the obtained emulsion was passed through a 200 mesh (mesh 105 μm) wire mesh. Thereafter, deionized water was added so that the solid content of the resin particle dispersion was 30% by mass to obtain a resin particle dispersion a-1. Table 3 shows the physical properties.

Production Examples 18 to 32
(Production of resin particle dispersions a-2 to a-6, b-1 to b-10)
Resin particle dispersions a-2 to a-6 and b-1 to b-10 were obtained in the same manner as in Production Example 17 except that the amorphous polyester was changed as shown in Tables 3 and 4. The physical properties are shown in Table 3 and Table 4.

Production Example 33
(Production of release agent particle dispersion)
In a 1 liter beaker, 3.8 g of a sodium acrylate-sodium maleate copolymer aqueous solution “Poise 521” (manufactured by Kao Corporation, effective concentration 40% by mass) is dissolved in 200 g of deionized water as a sodium polycarboxylate aqueous solution. After that, 5 g of carnauba wax “Carnauba Wax No. 1” (manufactured by Kato Hiroyuki, melting point 83 ° C.) and paraffin wax “HNP-9” (manufactured by Nippon Seiki Co., Ltd., melting point 75 ° C.) 45 g were added, While maintaining the temperature at 90 to 95 ° C., the mixture was melted and stirred to obtain a molten mixture in which carnauba wax and paraffin wax were fused together.
The aqueous solution containing the obtained molten mixture was further subjected to a dispersion treatment for 30 minutes with an ultrasonic homogenizer “US-600T” (manufactured by Nippon Seiki Co., Ltd.) while maintaining the temperature at 90 to 95 ° C., and then cooled to room temperature. Deionized water was added thereto to adjust the release agent solid content to 20% by mass to obtain a release agent particle dispersion. The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion was 0.45 μm, and the CV value was 30%.

Example 1
(Preparation of Toner 1)
200 g of resin particle dispersion a-1, 75 g of deionized water, and 26 g of release agent particle dispersion were added at a temperature of 25 ° C. to a 2-liter four-necked flask equipped with a dehydration tube, a stirrer, and a thermocouple. Mixed. Next, while stirring the mixture, temperature increase was started while dropping an aqueous solution of 18 g of ammonium sulfate in 215 g of deionized water over 30 minutes, and the temperature was increased to 50 ° C. at 10 ° C./hour. The mixture was held at 50 ° C. until the volume median particle size became 4.3 μm to obtain a dispersion of aggregated particles (1).

Next, 61 g of resin particle dispersion b-1 was added dropwise at 0.4 ml / min while raising the temperature of the dispersion of the aggregated particles (1) from 50 ° C. to 55 ° C. at 2.0 ° C./hour, A dispersion of aggregated particles (2) was obtained.
An aqueous solution in which 15 g of an anionic surfactant “Emar E-27C” (manufactured by Kao Corporation, effective concentration: 27 mass%) and 594 g of deionized water were added to the aggregated particle (2) dispersion. The temperature was raised to 70 ° C. over 1 hour and held at 70 ° C. for 1 hour to fuse the particles to obtain a dispersion of toner particles having a core-shell structure.

  The obtained toner particle dispersion was cooled to 30 ° C., and the solid content of the dispersion was separated by suction filtration, washed with deionized water, and dried at 33 ° C. to isolate the toner particles. . 100 parts by mass of the toner particles, 2.5 parts by mass of hydrophobic silica “RY50” (manufactured by Nippon Aerosil Co., Ltd., number average particle size; 0.04 μm), and hydrophobic silica “Cabo Seal TS720” (manufactured by Cabot, number average particles) 1.0 part by mass (diameter: 0.012 μm) was put in a Henschel mixer, stirred, and passed through a 150-mesh sieve to obtain toner 1. Table 5 shows the physical properties and evaluation of the toner.

Examples 2-8 and Comparative Examples 1-10
(Production of toners 2 to 18)
Toners 2 to 18 were obtained in the same manner as in Example 1 except that the resin particle dispersions a-1 and b-1 in Example 1 were changed to the resin particle dispersions shown in Tables 5 and 6. . The physical properties and evaluation of the toner are shown in Table 5 and Table 6.

  From Tables 5 and 6, it can be seen that the electrophotographic toners of the examples have both low-temperature fixability and heat-resistant storage stability and excellent document offset resistance as compared to the electrophotographic toners of the comparative examples.

  The toner of the present invention can be suitably used as a toner used in electrophotography because it has both low-temperature fixability and heat-resistant storage stability and excellent document offset resistance. According to the method of the present invention, an electrophotographic toner having such characteristics can be produced efficiently.

Claims (4)

An electrophotographic toner having a core-shell structure,
The core part is obtained by polycondensation of an alcohol component and a carboxylic acid component which may contain succinic acid having an alkyl group having 8 to 14 carbon atoms and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms. Containing polyester (A),
Polyester obtained by polycondensing an alcohol component and a carboxylic acid component containing a succinic acid having an alkyl group having 8 to 14 carbon atoms and / or an alkenyl group having 8 to 14 carbon atoms in a shell portion Containing (B),
An electrophotographic toner in which the polyester (A) and the polyester (B) satisfy the following (i) to (iii).
(I) The glass transition temperature of the polyester (B) is 35 ° C. or higher and 80 ° C. or lower.
(Ii) The glass transition temperature of the polyester (B) is 3 ° C. or more higher than the glass transition temperature of the polyester (A).
(Iii) The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (A) is XA The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of polyester (B) is XB. Then, the relationship XB−XA ≧ 15 is satisfied.   The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (B) is 15 mol% or more. The electrophotographic toner according to claim 1, wherein the toner is 60 mol% or less.   The electrophotographic toner according to claim 1, wherein the polyester (B) contains 2,2-bis (4-hydroxycyclohexyl) propane in an alcohol component. A method for producing an electrophotographic toner comprising the following steps (1) to (3):
Step (1): an alcohol component and a carboxylic acid component that may contain succinic acid having an alkyl group having 8 to 14 carbon atoms and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms are polycondensed. Step of aggregating the obtained resin particles (a) containing the polyester (A) to obtain aggregated particles (1) Step (2): In the aggregated particles (1), an alcohol component and an alkyl having 8 to 14 carbon atoms. Resin particles (b) containing polyester (B) obtained by polycondensation with a carboxylic acid component containing succinic acid having a group and / or succinic acid having an alkenyl group having 8 to 14 carbon atoms, Step for obtaining aggregated particles (2) Step (3): Step for obtaining toner particles having a core-shell structure by fusing the aggregated particles (2) Polyester (A) and polyester (B) There follows (i) ~ (iii) the manufacturing method of the electrophotographic toner satisfying.
(I) The glass transition temperature of the polyester (B) is 35 ° C. or higher and 80 ° C. or lower.
(Ii) The glass transition temperature of the polyester (B) is 3 ° C. or more higher than the glass transition temperature of the polyester (A).
(Iii) The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of the polyester (A) is XA The total content (mol%) of succinic acid having an alkyl group having 8 to 14 carbon atoms and succinic acid having an alkenyl group having 8 to 14 carbon atoms in the carboxylic acid component of polyester (B) is XB. Then, the relationship XB−XA ≧ 15 is satisfied.