JP6318063B2 - Image forming method - Google Patents

Description

  The present invention relates to an image forming method, a method for producing an aqueous dispersion of a binder resin composition, and a method for producing an electrophotographic toner.

  In the field of electrophotography, with the development of an electrophotographic system, development of toner for electrophotography corresponding to higher image quality and higher speed is required. Corresponding to high image quality, a method of obtaining a toner having a narrow particle size distribution and a small particle size is obtained by aggregating and fusing fine resin particles in an aqueous medium to obtain a toner. A toner is manufactured by an aggregation method or an aggregation fusion method. As the binder resin, a styrene acrylic resin or a polyester resin excellent in low-temperature fixability is used, and in order to satisfy a plurality of performances simultaneously, a combination of a plurality of resins has been studied. In addition, with the diversification of print media, the development of so-called label printing applications in which printing is performed not only on conventional paper but also on the surface of polyolefin films or the like has begun.

  For example, Patent Document 1 discloses a method for producing a polyester resin for a toner capable of providing a toner having storage stability, good low-temperature fixability, and a wide non-offset temperature range, in the presence of sterols. A method for polycondensation of an acid and a monomer mixture containing a polyhydric alcohol is disclosed.

JP 2011-232666 A

In Patent Document 1, improvement in storage stability, low-temperature fixability, etc. of the toner is attempted, but no examination has been made from the viewpoint of adhesion to the polyolefin film, and adhesion to the polyolefin film is insufficient. there were. In addition, further improvements have been desired for low-temperature fixability and heat-resistant storage stability.
The present invention provides [1] an image forming method excellent in low temperature fixability and adhesion to a polyolefin film, and [2] a toner capable of obtaining low temperature fixability, heat resistant storage stability and excellent adhesion to a polyolefin film. It is an object of the present invention to provide a method for producing an aqueous dispersion of a resin composition, [3] a method for producing an electrophotographic toner excellent in low-temperature fixability, heat resistant storage stability, and adhesion to a polyolefin film.

  The present inventors have found that a toner having excellent low-temperature fixability, heat-resistant storage stability, and adhesion to a polyolefin film can be obtained by controlling the sterol content in the polyester-based resin within a specific range. The present invention has been completed.

That is, the present invention provides the following image forming method, method for producing an aqueous dispersion of a binder resin composition, and method for producing an electrophotographic toner.
[1] A charging process for charging the photoreceptor, an exposure process for exposing the photoreceptor, a developing process for forming a toner image by attaching toner to an electrostatic latent image formed on the photoreceptor, and An image forming method comprising a transfer step of transferring a toner image to a recording medium and a fixing step of fixing the transferred toner image to a recording medium, wherein the toner contains 5% by mass or more and 35% by mass of a structural unit derived from sterol. % Is an electrophotographic toner comprising a binder resin composition containing a polyester-based resin and a wax, and the recording medium is a polyolefin film.
[2] A method for producing an aqueous dispersion of the binder resin composition according to [1], comprising the following steps 1 and 2.
Step 1: Polyester system containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and sterol in the presence of wax. Step of obtaining a mixture containing resin and wax Step 2: An aqueous medium is added to the binder resin composition containing the mixture obtained in Step 1, and phase inversion emulsification is performed. Step [3] for obtaining an aqueous dispersion [3] The method for producing an electrophotographic toner according to [1] above, comprising the following steps 1 to 3.
Step 1: Polyester system containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and sterol in the presence of wax. Step of obtaining a mixture containing resin and wax Step 2: An aqueous medium is added to the binder resin composition containing the mixture obtained in Step 1, and phase inversion emulsification is performed. Step of obtaining aqueous dispersion Step 3: Step of aggregating and fusing the aqueous dispersion obtained in Step 2

  According to the present invention, [1] an image forming method excellent in low temperature fixability and adhesion to a polyolefin film, and [2] a toner excellent in low temperature fixability, heat resistant storage stability and adhesion to a polyolefin film can be obtained. A method for producing an aqueous dispersion of a binder resin composition for toner, [3] a method for producing an electrophotographic toner excellent in low-temperature fixability, heat-resistant storage, and adhesion to a polyolefin film can be provided.

[Image forming method]
The image forming method of the present invention includes a charging step for charging a photosensitive member, an exposure step for exposing the photosensitive member, and a developing step for forming a toner image by attaching toner to an electrostatic latent image formed on the photosensitive member. And a transfer step of transferring the formed toner image to a recording medium, and a fixing step of fixing the transferred toner image to the recording medium, wherein the toner contains 5 units of structural units derived from sterol. An electrophotographic toner comprising a binder resin composition containing a polyester-based resin and a wax containing at least 35% by mass and less than 35% by mass, wherein the recording medium is a polyolefin film.

The reason why the image forming method of the present invention is excellent in low-temperature fixability and adhesion to a polyolefin film is not clear, but is considered as follows.
The toner used in the image forming method of the present invention contains a polyester resin containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol.
The sterol is bonded to the terminal of the polyester, and the polyester resin becomes a high molecular weight in a pseudo manner due to the interaction between the sterol groups. Therefore, it is considered that the heat resistant storage stability of the toner is improved.
On the other hand, since sterols have a property of sharp melting (sharp melt properties), the interaction between sterol groups contributing to the above-described pseudo high molecular weight rapidly weakens near the fixing temperature. The toner is considered to be excellent in low-temperature fixability.
Furthermore, since the polyester resin having a sterol group and the polyolefin film having a hydrophobic surface have high affinity and are easy to adhere, an image having excellent adhesion to the polyolefin film can be obtained according to the image forming method of the present invention. It is thought that.
Hereinafter, each step of the image forming method of the present invention will be described.

<Charging process>
The charging step is a step of uniformly charging the surface of the photoreceptor positively or negatively by the charging member. The charging method is not particularly limited, and a conventionally known method such as a contact charging method in which charging is performed with a charging roll, a fur brush, a magnetic brush, a blade, or the like, or a non-contact charging method using corona discharge can be employed. .
<Exposure process>
The exposure step is a step of irradiating the surface of the photoconductor with light corresponding to an image signal by an exposure device such as a laser beam irradiation device to form an electrostatic latent image on the uniformly charged surface of the photoconductor. . As the exposure apparatus, for example, a light source such as a laser, an LED, or an EL array can be used in combination with an image forming optical system.
<Development process>
The developing step is a step of forming a toner image by attaching toner to the electrostatic latent image formed on the photosensitive member by a developing device. The developing step can be performed using a conventionally known developing device. As the developing device, for example, a two-component magnetic brush developer, a one-component magnetic brush developer, a one-component nonmagnetic developer, or the like can be used.

(toner)
The toner used in the image forming method of the present invention is an electrophotographic toner comprising a binder resin composition containing a polyester-based resin containing 5% by mass to 35% by mass of a sterol-derived structural unit and a wax.
The binder resin composition is not particularly limited as long as it contains a polyester-based resin containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol, and an optional component such as a colorant described later. May be included.

[Polyester resin]
The polyester resin is not particularly limited as long as it contains 5% by mass to 35% by mass of a structural unit derived from sterol, and other than the polyester resin, a polyester modified to such an extent that its properties are not substantially impaired. May be included. Examples of the modified polyester include a urethane-modified polyester in which the polyester is modified with a urethane bond, an epoxy-modified polyester in which the polyester is modified with an epoxy bond, and two or more resins including a polyester resin segment and a vinyl resin segment Examples thereof include composite resins having components. Among these, a polyester resin is preferable from the viewpoints of the minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film.

  The content of the polyester-based resin in the toner used in the present invention is preferably 60% by mass or more, more preferably 70% by mass or more, from the viewpoint of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. Preferably it is 80 mass% or more, and preferably 98 mass% or less, More preferably, it is 93 mass% or less, More preferably, it is 90 mass% or less.

Examples of sterols include plant sterols (phytosterols) such as β-sitosterol, stigmasterol, brassicasterol, and campesterol; animal sterols such as cholesterol and lanosterol; and fungal sterols such as ergosterol.
Plant sterols are included in soybeans, rapeseed, cottonseed, tall, red beans, sugar cane, etc. among plants, and soy-derived phytosterols manufactured by Tama Seikagaku Co., Ltd. are commercially available. . Soy-derived phytosterol is a mixture containing β-sitosterol as a main component and stigmasterol, campesterol, and the like.
Among these, animal sterols are preferable and cholesterol is more preferable from the viewpoint of minimum fixing temperature, heat-resistant storage stability, and adhesion to polyolefin films.

The content of the structural unit derived from sterol in the polyester-based resin is 5% by mass or more and 35% by mass or less, preferably 10% by mass, from the viewpoint of the minimum fixing temperature, the heat resistant storage stability, and the adhesion to the polyolefin film. Or more, more preferably 15% by mass or more, still more preferably 18% by mass or more, and preferably 30% by mass or less, more preferably 28% by mass from the viewpoints of heat-resistant storage stability and adhesion to a polyolefin film. Hereinafter, it is more preferably 25% by mass or less.
The reaction rate of sterol is preferably 90% or more, more preferably 95% or more, and still more preferably 97% or more, from the viewpoints of minimum fixing temperature, heat-resistant storage stability, and adhesion to polyolefin film. Is 100% or less.
The reaction rate of sterol can be measured by the method described in Examples.

≪Softening point≫
The softening point of the polyester-based resin is preferably 85 ° C. or higher, more preferably 95 ° C. or higher, more preferably 105 ° C. or higher, from the viewpoint of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. The temperature is preferably 130 ° C. or lower, more preferably 120 ° C. or lower, and still more preferably 115 ° C. or lower.
≪Glass transition temperature≫
The glass transition temperature of the polyester-based resin is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, more preferably 50 ° C. or higher, from the viewpoint of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. And preferably it is 90 degrees C or less, More preferably, it is 80 degrees C or less, More preferably, it is 70 degrees C or less.
≪Acid value≫
The acid value of the polyester-based resin is preferably 4 mgKOH / g or more, more preferably 6 mgKOH / g or more, and still more preferably 8 mgKOH / g or more, from the viewpoint of the minimum fixing temperature, heat-resistant storage stability, and adhesion to the polyolefin film. Yes, and preferably 25 mgKOH / g or less, more preferably 20 mgKOH / g or less, still more preferably 15 mgKOH / g or less, and even more preferably 14 mgKOH / g or less.
The softening point, the glass transition temperature, and the acid value of the polyester resin can be appropriately adjusted 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. A softening point, a glass transition temperature, and an acid value are calculated | required by the method as described in an Example.
Hereinafter, the suitable aspect in the case of using a polyester resin as a polyester-type resin is demonstrated.

≪Polyester resin production method≫
The polyester resin can be produced by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and sterol.

{Alcohol component}
The alcohol component includes a polyhydric alcohol and a sterol. In the polycondensation of the alcohol component and the polyvalent carboxylic acid component, it is preferable that sterol is present from the beginning because the reaction rate of sterol can be improved.
The sterol content in the alcohol component is preferably at least 10 mol%, more preferably at least 15 mol%, still more preferably at least 20 mol%, from the viewpoints of the minimum fixing temperature, heat-resistant storage stability, and adhesion to polyolefin films. From the viewpoints of heat-resistant storage stability and adhesion to a polyolefin film, it is preferably 40 mol% or less, more preferably 35 mol% or less, still more preferably 30 mol% or less.

Examples of the polyhydric alcohol component include aliphatic diols, aromatic diols, and trihydric or higher polyhydric alcohols. These alcohol components can be used alone or in combination of two or more.
The alcohol component preferably contains an alkylene oxide adduct of bisphenol A represented by the following formula (I) from the viewpoint of the minimum fixing temperature, heat-resistant storage stability, and adhesion to the polyolefin film.

(Wherein R ¹ O is an alkylene oxide, R ¹ is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average number of moles of alkylene oxide added, and the sum of x and y is The number is preferably 1 or more, more preferably 1.5 or more, still more preferably 2 or more, and preferably 16 or less, more preferably 5 or less, still more preferably 3 or less.

As the alkylene oxide adduct of bisphenol A represented by the above formula (I), specifically, a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4- Hydroxyphenyl) propane polyoxyethylene adduct, etc., and 2,2-bis (4-hydroxyphenyl) propane polyoxypropylene from the viewpoint of minimum fixing temperature, heat-resistant storage stability, and adhesion to polyolefin film Adducts are preferred.
The content of the alkylene oxide adduct of bisphenol A represented by the above formula (I) in the alcohol component is preferably 40 mol% from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film. Or more, more preferably 50 mol% or more, still more preferably 60 mol% or more, still more preferably 65 mol% or more, and preferably 90 mol% or less, more preferably 85 mol% or less, still more preferably 80 mol% or more. It is less than mol%.

  In the alcohol component, the total content of the sterol and the alkylene oxide adduct of bisphenol A is preferably 80% by mass or more, more preferably from the viewpoint of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. Is 90% by mass or more, more preferably 98% by mass or more, and still more preferably 100% by mass.

{Polyvalent carboxylic acid component}
Examples of the polyvalent carboxylic acid component include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, trivalent or higher polyvalent carboxylic acids, acid anhydrides thereof, and alkyl (1 to 3 carbon atoms) esters thereof. . These polyvalent carboxylic acid components can be used alone or in combination of two or more.
The number of carbon atoms in the main chain of the aliphatic dicarboxylic acid is preferably 4 or more, and preferably 10 or less, more preferably 8 or less, from the viewpoints of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. More preferably, it is 6 or less.
Specific examples include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, dodecane. A diacid etc. are mentioned. Examples of the aliphatic dicarboxylic acid include succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms such as dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid. . Among these, fumaric acid, dodecenyl succinic acid, and octenyl succinic acid are preferable, and fumaric acid is more preferable from the viewpoint of minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film.
Examples of the aromatic dicarboxylic acid include terephthalic acid, phthalic acid, and isophthalic acid. Among these, terephthalic acid is preferable from the viewpoints of the minimum fixing temperature, the heat resistant storage stability, and the adhesion to the polyolefin film.

The content of the aliphatic dicarboxylic acid is preferably 10 mol% or more, more preferably 15 mol% or more, in the polyvalent carboxylic acid component, from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film. More preferably, it is 20 mol% or more, and preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 30 mol% or less.
Further, from the same viewpoint, the content of the aromatic dicarboxylic acid is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 60 mol% or more in the polyvalent carboxylic acid component, and Preferably it is 90 mol% or less, More preferably, it is 80 mol% or less, More preferably, it is 75 mol% or less.
The molar ratio of the aliphatic dicarboxylic acid to the aromatic dicarboxylic acid [aliphatic dicarboxylic acid / aromatic dicarboxylic acid] is preferably 10/90 to 60/40, more preferably 15/85 to the same viewpoint as described above. 50/50, more preferably 20/80 to 40/60.
From the same viewpoint, the total amount of aliphatic dicarboxylic acid and aromatic dicarboxylic acid in the polyvalent carboxylic acid component is preferably 80 mol% or more, more preferably 85 mol% or more, and still more preferably 90 mol% or more. And preferably 100 mol% or less.

Specific examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and the like. Minimum fixing temperature, heat resistant storage stability, and adhesion to polyolefin film From the viewpoint of safety, trimellitic acid is preferable.
In the case of using a trivalent or higher polyvalent carboxylic acid, the content thereof is preferably 0.1 mol% or higher, more preferably 1 mol% or higher, more preferably 3 in the polyvalent carboxylic acid component from the same viewpoint. It is at least mol%, and preferably at most 30 mol%, more preferably at most 20 mol%, still more preferably at most 10 mol%.
Among these, from the viewpoint of minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film, it is preferable to include an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid having 4 to 8 carbon atoms. It is more preferable to include an acid, an aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and a trivalent or higher polyvalent carboxylic acid compound, and it is more preferable to use fumaric acid, terephthalic acid, and trimellitic acid in combination. .

  From the viewpoint of adjusting physical properties, the alcohol component may optionally contain a monovalent alcohol, and the polyvalent carboxylic acid component may suitably contain a monovalent carboxylic acid compound.

{Reaction conditions}
A polyester resin is formed by a polycondensation reaction between the alcohol component and the polyvalent carboxylic acid component.
From the viewpoint of reactivity, the polycondensation reaction temperature is preferably 160 ° C. or higher, more preferably 200 ° C. or higher, still more preferably 220 ° C. or higher, and preferably 260 ° C. or lower, more preferably 250 ° C. or lower. More preferably, it is 240 degrees C or less.
The molar ratio of the polyvalent carboxylic acid component to the alcohol component [(alcohol component) / (polyvalent carboxylic acid component)]) is preferably 1 from the viewpoints of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film. 0.000 or more, more preferably 1.05 or more, further preferably 1.10 or more, and preferably 1.30 or less, more preferably 1.25 or less, and further preferably 1.20 or less.
The polycondensation reaction may be performed in an inert gas atmosphere in the presence of an esterification catalyst, an esterification cocatalyst, a polymerization inhibitor, or the like, if necessary.

{Esterification catalyst}
Examples of the esterification catalyst suitably used for the polycondensation reaction include a titanium compound and a tin (II) compound having no Sn—C bond, and these may be used alone or in combination of two or more. it can.
As the titanium compound, a titanium compound having a Ti—O bond is preferable, and a compound having an alkoxy group, an alkenyloxy group or an acyloxy group having 1 to 28 carbon atoms in total is more preferable.
Examples of the tin (II) compound having no Sn—C bond include a tin (II) compound having a Sn—O bond, a tin (II) compound having a Sn—X (X represents a halogen atom) bond, and the like. Preferred is a tin (II) compound having a Sn-O bond, and among them, di (2-ethylhexanoic acid) tin (II) is more preferable from the viewpoints of reactivity, molecular weight adjustment, and physical property adjustment of a polyester resin. preferable.
The amount of the esterification catalyst used is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the total amount of the alcohol component and the polyvalent carboxylic acid component, from the viewpoint of reactivity, molecular weight adjustment, and physical property adjustment of the polyester resin. More preferably 0.1 parts by mass or more, still more preferably 0.4 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.2 parts by mass or less, still more preferably 0.8 parts by mass. It is below mass parts.

{Esterification cocatalyst}
As the esterification cocatalyst, a pyrogallol compound is preferred. This pyrogallol compound has a benzene ring in which three hydrogen atoms adjacent to each other are substituted with a hydroxyl group, and pyrogallol, gallic acid, gallic acid ester, 2,3,4-trihydroxybenzophenone, 2,2 ′ Benzophenone derivatives such as 3,3,4-tetrahydroxybenzophenone, catechin derivatives such as epigallocatechin and epigallocatechin gallate, and the like, and gallic acid is preferred from the viewpoint of reactivity.
The use amount of the esterification cocatalyst is preferably 0.001 part by mass or more with respect to 100 parts by mass of the total amount of the alcohol component and the polyvalent carboxylic acid component from the viewpoints of reactivity, molecular weight adjustment and physical property adjustment of the polyester resin More preferably 0.01 parts by mass or more, still more preferably 0.03 parts by mass or more, and preferably 0.15 parts by mass or less, more preferably 0.10 parts by mass or less, still more preferably 0.07 parts by mass. It is below mass parts.
From the viewpoint of reactivity, the mass ratio of the esterification cocatalyst to the esterification catalyst (esterification cocatalyst / esterification catalyst) is preferably 0.001 or more, more preferably 0.01 or more, and still more preferably 0.00. It is 05 or more, and preferably 0.5 or less, more preferably 0.3 or less, and still more preferably 0.2 or less.
{Polymerization inhibitor}
Examples of the polymerization inhibitor include 4-t-butylcatechol.

〔wax〕
The toner used in the present invention contains a wax from the viewpoint of the minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film.
As the wax, ester wax, hydrocarbon wax, silicone wax, fatty acid amide and the like can be used. Among these, hydrocarbon waxes and ester waxes are preferable, and hydrocarbon waxes are more preferable from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to polyolefin films.
Examples of the ester wax include synthetic ester wax and natural ester wax. Examples of the synthetic ester wax include esters composed of a long-chain alcohol and a fatty acid, and preferably at least one fatty acid ester of behenyl behenate, stearyl stearate, and pentaerythritol. The natural ester wax is preferably at least one of carnauba wax and rice wax. Among these, from the viewpoint of minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film, a synthetic ester wax is preferable, an ester composed of a long-chain alcohol and a fatty acid is more preferable, and a fatty acid ester of pentaerythritol is more preferable. Pentaerythritol behenate is even more preferable.
Specific examples of the hydrocarbon wax include low-molecular-weight polyolefins such as polyethylene, polypropylene, and polybutene; minerals such as ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax, and petroleum-based wax, preferably paraffin wax. It is.
The content of the wax in the toner is preferably 2% by mass or more, more preferably 5% by mass in the total amount of the polyester resin and the wax from the viewpoints of the minimum fixing temperature, heat-resistant storage stability, and adhesion to the polyolefin film. % Or more, more preferably 8% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less.

[Optional ingredients]
The binder resin composition and toner used in the present invention may contain a known resin used in the toner, for example, polyester, styrene-acrylic copolymer, epoxy, polycarbonate, polyurethane and the like.
The binder resin composition and toner used in the present invention further include a colorant, a charge control agent, magnetic powder, a fluidity improver, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, and an antioxidant. In addition, additives such as an antiaging agent and a cleaning property improving agent may be appropriately contained.
In the present specification, a resin component including a polyester-based resin and the above-described known resin that is optionally used may be referred to as a “binder resin”.
The content of the polyester-based resin in the binder resin is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably, from the viewpoints of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. It is 95 mass% or more, More preferably, it is 100 mass%.

≪Colorant≫
There is no restriction | limiting in particular as a coloring agent, A well-known coloring agent is mentioned, According to the objective, it can select suitably. Specifically, carbon black, inorganic composite oxide, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, Brilliantamine 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Various pigments: acridine, xanthene, azo, benzoquinone, azine, anthraquinone, indico, Indigo dyes, phthalocyanine, aniline black, polymethine, triphenylmethane dyes, diphenylmethane dyes, thiazine, and include various dyes of thiazole, and the like. These can be used alone or in combination of two or more.
The content of the colorant in the toner is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the binder resin, from the viewpoint of improving the image density of the toner. The amount is preferably 1.0 part by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less.

≪Charge control agent≫
Examples of charge control agents include chromium azo dyes, iron azo dyes, aluminum azo dyes, and salicylic acid metal complexes. You may use a charge control agent individually or in combination of 2 or more types.
The content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably 0 with respect to 100 parts by mass of the binder resin from the viewpoint of charging stability of the toner. 0.5 parts by mass or more, and preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, and still more preferably 1.5 parts by mass or less.

The volume median particle size (D ₅₀ ) of the toner used in the present invention is preferably 2 μm or more, more preferably 4 μm or more, and still more preferably, from the viewpoints of the minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film. It is 6 μm or more, and preferably 15 μm or less, more preferably 12 μm or less, and still more preferably 10 μm or less.
Next, a method for producing the toner used in the present invention will be described.

(Toner production method)
The toner used in the present invention can be produced by a known method such as a suspension polymerization method, a suspension method, a pulverization method, or an aggregation fusion method. Among these, the cohesive fusion method is preferable from the viewpoint of the minimum fixing temperature, the heat resistant storage stability, and the adhesion to the polyolefin film.

Examples of the suspension polymerization method include, for example, polymerizing the vinyl monomer while mixing a polyester resin and wax, a vinyl monomer such as an acrylic monomer, and an optional component such as a colorant in an aqueous medium. Examples of the method include forming toner mother particles containing a polyester resin in an aqueous medium, and drying and washing the toner mother particles.
As a suspension method, a toner base particle is formed by suspending a composition containing a polyester-based resin, a wax, and the optional component in a solvent such as water using a known disperser, etc. The method of drying, washing, etc. is mentioned.
As a pulverization method, polyester resin, wax, and the above optional components are uniformly mixed with a mixer such as a Henschel mixer, and then melted with a hermetic kneader, a single or twin screw extruder, an open roll kneader, or the like. Examples of the method include kneading, cooling, pulverization, and classification.
Hereinafter, the cohesive fusion method will be described in detail.

The toner production method by the cohesive fusion method preferably includes the following steps I and II.
Step I: Step of obtaining an aqueous dispersion of the binder resin composition by adding an aqueous medium to the binder resin composition containing the polyester resin and performing phase inversion emulsification Step II: obtained in Step I Aggregating and fusing the aqueous dispersion

[Step I]
Step I is a step of adding an aqueous medium to the binder resin composition containing the polyester resin and performing phase inversion emulsification to obtain an aqueous dispersion of the binder resin composition.
In this specification, the aqueous dispersion may be the dispersion resin in which the binder resin composition is present in a solvent containing an aqueous medium. The aqueous dispersion is preferably present at 25 ° C. for 24 hours without separation.
In this specification, particles made of the binder resin composition contained in the aqueous dispersion of the binder resin composition may be referred to as “binder resin particles”.
The aqueous dispersion may contain an organic solvent other than the aqueous medium, but the content of the aqueous medium in the total amount of the aqueous medium and the organic solvent is preferably 50% by mass or more, more preferably 70% by mass. As mentioned above, More preferably, it is 80 mass% or more, More preferably, it is 85 mass% or more.
Hereinafter, the phase inversion emulsification method will be described.

In the phase inversion emulsification, first, a polyester resin, a surfactant to be added as necessary, and other optional components described above are dissolved or dispersed in an organic solvent, and a binder resin containing the polyester resin and the optional components. This can be done by obtaining an organic solvent solution of the composition and then adding an aqueous medium to the resulting solution.
The wax may be added when preparing the binder resin composition, or may be added as a wax particle dispersion in the subsequent aggregation step. From the viewpoint of adhesiveness, it is preferable to add at the time of the polycondensation reaction of the polyester resin as in Step 1 described later.
In step I, it is preferable to add a neutralizing agent to the binder resin composition from the viewpoint of improving the dispersion stability of the binder resin composition.

≪Organic solvent≫
From the viewpoint of improving the dispersion stability of the binder resin particles, the organic solvent is preferably 15.0 MPa ¹ when expressed by a solubility parameter (SP value: POLYMER HANDBOOK THIRD EDITION 1989 by John Wiley & Sons, Inc). ^{/ 2} or more, more preferably 16.0 MPa ^1/2 or more, still more preferably 17.0 MPa ^1/2 or more, and preferably 26.0 MPa ^1/2 or less, more preferably 24.0 MPa ^1/2 or less. More preferably, it is 22.0 MPa ^1/2 or less.
Specific examples include the following organic solvents. The parentheses on the right side of the name of the next organic solvent are SP values, and the unit is MPa ^1/2 . That is, specific examples include alcohol solvents such as ethanol (26.0), isopropanol (23.5), and isobutanol (21.5); acetone (20.3), methyl ethyl ketone (19.0), methyl Ketone solvents such as isobutyl ketone (17.2) and diethyl ketone (18.0); ether solvents such as dibutyl ether (16.5), tetrahydrofuran (18.6) and dioxane (20.5); Examples thereof include acetate solvents such as ethyl acetate (18.6) and isopropyl acetate (17.4). Among these, from the viewpoint of minimum fixing temperature, heat resistant storage stability, and adhesion to polyolefin film, ketone solvents and acetate solvents are preferable, and one or more selected from methyl ethyl ketone, ethyl acetate, and isopropyl acetate are more preferable. Further, a ketone solvent is more preferable, and methyl ethyl ketone is still more preferable.

  The mass ratio between the organic solvent and the binder resin composition (organic solvent / binder resin composition) is based on the viewpoint of dissolving the polyester resin and facilitating phase inversion into an aqueous medium, as well as the dispersion of the binder resin particles. From the viewpoint of improving the stability, it is preferably 0.05 or more, more preferably 0.1 or more, still more preferably 0.2 or more, and preferably 3 or less, more preferably 2 or less, still more preferably 1 It is as follows.

≪Neutralizer≫
Examples of neutralizing agents include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; organic bases such as ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, triethanolamine, and tributylamine. It is done. Among these, sodium hydroxide is preferable from the viewpoints of minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film.
The temperature when neutralizing by adding a neutralizing agent is preferably 30 ° C or higher, more preferably 50 ° C or higher, still more preferably 60 ° C or higher, and preferably 90 ° C or lower, more preferably 85 ° C. Below, it is 80 degrees C or less more preferably.
The degree of neutralization (mol%) of the polyester resin with the neutralizing agent is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, and preferably 150 mol% or less. More preferably, it is 100 mol% or less, More preferably, it is 60 mol% or less.
In addition, the neutralization degree (mol%) of a polyester-type resin can be calculated | required by a following formula.
Degree of neutralization = {[addition mass of neutralizer (g) / equivalent of neutralizer] / [[acid value of polyester resin (mgKOH / g) × resin mass (g)] / (56 × 1000) ] × 100

≪Aqueous medium≫
As the aqueous medium, those containing water as a main component are preferable.
Components other than water include aliphatic alcohols having 1 to 5 carbon atoms such as methanol, ethanol, isopropanol and butanol; dialkyl (1 to 3 carbon atoms) ketones such as acetone and methyl ethyl ketone; cyclic ethers such as tetrahydrofuran, etc. Examples include organic solvents that dissolve in water. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the polyester-based resin, can be suitably used from the viewpoint of preventing mixing into the toner.
The content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably, from the viewpoint of improving the dispersion stability of the binder resin particles. Is 100% by mass. The water is preferably deionized water or distilled water.

From the viewpoint of improving the dispersion stability of the binder resin particles, the temperature at which the aqueous medium is added is preferably 15 ° C. or higher, more preferably 20 ° C. or higher, further preferably 25 ° C. or higher, and preferably 80 ° C. or lower, more preferably 60 ° C. or lower, and further preferably 40 ° C. or lower.
From the viewpoint of improving the dispersion stability of the binder resin particles, the addition rate of the aqueous medium is preferably 0.1 parts by mass / min with respect to 100 parts by mass of the binder resin composition until the phase inversion is completed. Or more, more preferably 1 part by mass / min or more, further preferably 3 parts by mass / min or more, and preferably 50 parts by mass / min or less, more preferably 20 parts by mass / min or less, still more preferably 10 parts by mass. Parts / minute or less. There is no restriction | limiting in the addition rate of the aqueous medium after phase inversion.
The amount of the aqueous medium to be added is preferably based on 100 parts by mass of the binder resin composition from the viewpoint of improving the dispersion stability of the binder resin particles and obtaining uniform aggregated particles in the subsequent aggregation step. 100 parts by mass or more, more preferably 200 parts by mass or more, still more preferably 400 parts by mass or more, and preferably 900 parts by mass or less, more preferably 700 parts by mass or less, still more preferably 500 parts by mass or less.

≪Surfactant≫
Examples of the surfactant include nonionic surfactants, anionic surfactants, and cationic surfactants. Among these, from the viewpoint of improving the dispersion stability of the binder resin particles, at least one selected from a nonionic surfactant and an anionic surfactant is preferable, and an anionic surfactant is more preferable.
Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene lauryl ether or polyoxyethylene alkyl ethers, polyethylene glycol monolaurate, Examples include polyethylene glycol monostearate, polyoxyethylene fatty acid esters such as polyethylene glycol monooleate, and oxyethylene / oxypropylene block copolymers. Among these, from the viewpoint of improving the dispersion stability of the binder resin particles, Polyoxyethylene alkyl ethers are preferred.
Examples of the anionic surfactant include alkylbenzene sulfonates such as sodium alkylbenzene sulfonate, alkyl sulfates such as sodium alkyl sulfate, alkyl ether sulfates such as sodium alkyl ether sulfate, etc. Among these, binder resins From the viewpoint of improving the dispersion stability of the particles, sodium alkylbenzene sulfonate and alkyl ether sulfate are preferable, and alkyl ether sulfate is more preferable.
Examples of the cationic surfactant include alkyltrimethylammonium chloride and dialkyldimethylammonium chloride.
Among these, from the viewpoint of improving the dispersion stability of the binder resin particles, an anionic surfactant is preferable, and polyoxyethylene lauryl ether is more preferable.

≪Removal of organic solvent≫
You may have the process of removing an organic solvent from the dispersion obtained by phase inversion emulsification as needed after phase inversion emulsification.
The method for removing the organic solvent is not particularly limited, and any method can be used. However, since it is dissolved in water, it is preferably distilled. Further, the organic solvent may not be completely removed and may remain in the aqueous dispersion. In this case, the remaining amount of the organic solvent is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably substantially 0% in the aqueous dispersion.
When removing the organic solvent by distillation, it is preferable to raise the temperature to a temperature equal to or higher than the boiling point of the organic solvent to be used while stirring. Further, from the viewpoint of maintaining the dispersion stability of the binder resin particles, it is more preferable to raise the temperature to a temperature equal to or higher than the boiling point of the organic solvent to be used under reduced pressure and to distill it off. Note that the temperature may be increased after the pressure is reduced, or the pressure may be decreased after the temperature is increased. From the viewpoint of maintaining the dispersion stability of the binder resin particles, it is preferable to distill off at a constant temperature and pressure.

≪Addition of surfactant≫
You may have the process of mixing the said surfactant with an aqueous dispersion after the said phase inversion emulsification.
The amount of the surfactant added in this step is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably from the viewpoint of the dispersion stability of the binder resin particles. Is 90% by mass or more, and preferably 100% by mass or less.
The amount of the surfactant added in this step is preferably 0.5 parts by mass or more, more preferably 100 parts by mass with respect to 100 parts by mass of the binder resin composition, from the viewpoint of dispersion stability of the binder resin particles. 1 mass part or more, More preferably, it is 2 mass parts or more, Preferably it is 20 mass parts or less, More preferably, it is 10 mass parts or less, More preferably, it is 5 mass parts or less.
When the surfactant is added, it is preferable to stir with a commonly used mixing and stirring device such as an anchor blade or an external circulation stirring device.
When a mixing stirring device such as an anchor blade is used, the peripheral speed of stirring is preferably 20 m / min or more, more preferably 40 m / min or more, still more preferably 60 m / min or more, and still more preferably, from the viewpoint of dispersibility. Is 80 m / min or more, and preferably 200 m / min or less, more preferably 150 m / min or less, and still more preferably 100 m / min or less.
The temperature at which the surfactant is added is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, still more preferably 20 ° C. or higher, and preferably 50 ° C. from the viewpoint of dispersibility of the surfactant in water. ° C or lower, more preferably 40 ° C or lower, still more preferably 35 ° C or lower.

{Volume-median particle size (D _50)}
The volume median particle size (D ₅₀ ) of the binder resin particles in the aqueous dispersion is preferably 100 nm or more, more preferably 150 nm or more, from the viewpoints of minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film. More preferably, it is 200 nm or more, and preferably 800 nm or less, more preferably 600 nm or less, still more preferably 300 nm or less.
Here, the volume-median particle size is a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size, and is obtained by the method described in the examples.

[Step II]
Step II is a step of agglomerating and fusing the aqueous dispersion obtained in Step I.

≪Agglomeration process≫
The aggregation step is a step of aggregating the aqueous dispersion of the binder resin composition obtained by the above-described production method to obtain an aqueous dispersion of aggregated particles.
In this step, it is preferable to add a flocculant for efficient aggregation. In Step II, a coloring agent, a charge control agent, a wax, a conductivity adjusting agent, a reinforcing filler such as a fibrous substance, an antioxidant, and an anti-aging agent may be added before aggregation. Good.

{Flocculant}
As the flocculant, a cationic surfactant of a quaternary ammonium salt, an organic flocculant such as polyethyleneimine; and an inorganic flocculant such as an inorganic metal salt or an inorganic ammonium salt are used. Among these, an inorganic flocculant is preferable and an inorganic metal salt is more preferable from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to a polyolefin film.
Examples of the inorganic metal salt include sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, and aluminum chloride. Among these, calcium chloride is preferable. The valence of the central metal of the inorganic metal salt is preferably divalent or higher from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film.
The amount of the aggregating agent is preferably 0.1 parts by mass or more, more preferably 0, with respect to 100 parts by mass of the binder resin particles, from the viewpoint of controlling the aggregation of the binder resin particles to obtain a desired particle size. .15 parts by mass or more, more preferably 0.20 parts by mass or more, and preferably 5 parts by mass or less, more preferably 1 part by mass or less, still more preferably 0.5 parts by mass or less.
The flocculant is preferably added after being dissolved in an aqueous medium, and it is preferable that the flocculant is sufficiently stirred at the time of addition of the flocculant and after completion of the addition.
In the aggregation step, the solid content concentration in the system is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, from the viewpoint of causing uniform aggregation. It is 50 mass% or less, More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less.
The temperature at which the flocculant is dropped is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, further preferably 20 ° C. or higher, and preferably 45 ° C. or lower, from the viewpoint of improving the productivity of the toner. More preferably, it is 40 degrees C or less, More preferably, it is 35 degrees C or less, More preferably, it is 30 degrees C or less.

{Colorant}
Examples of the colorant used in the aggregation step include the same colorants that can be contained in the toner, and preferred embodiments thereof are also the same.
The colorant may be added as a colorant dispersion containing colorant particles.
The volume median particle size (D ₅₀ ) of the colorant particles is preferably 50 nm or more, more preferably 80 nm or more, still more preferably 100 nm or more, from the viewpoint of obtaining a toner capable of obtaining a high-quality image. Is 500 nm or less, more preferably 300 nm or less, and still more preferably 150 nm or less.

{Charge control agent}
Examples of the charge control agent used in the aggregation step include the same charge control agents that can be contained in the toner, and preferred embodiments thereof are also the same.
The charge control agent may be added as a charge control agent dispersion containing charge control agent fine particles. The volume median particle size (D ₅₀ ) of the charge control agent fine particles is preferably 100 nm or more, more preferably 200 nm or more, still more preferably 300 nm or more, and preferably 800 nm or less, more preferably 600 nm or less, Preferably it is 500 nm or less.

The volume-median particle size (D ₅₀ ) of the obtained aggregated particles is preferably 2 μm or more, more preferably 3 μm or more, and still more preferably 4 μm, from the viewpoints of minimum fixing temperature, heat resistant storage stability, and adhesion to polyolefin films. The thickness is preferably 10 μm or less, more preferably 8 μm or less, and still more preferably 6 μm or less.

≪Fusion process≫
The fusing step is a step of obtaining fused particles by fusing the binder resin particles in the agglomerated particles obtained in the aggregating step.
By this step, the particles in the aggregated particles, which are mainly physically attached to each other, are fused and united to form fused particles.

In this step, from the viewpoint of improving the fusing property of the aggregated particles, and from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film, the temperature is maintained at a temperature equal to or higher than the glass transition temperature of the polyester resin. Is preferred.
The holding temperature in the fusing step is preferably at least 10 ° C. higher than the glass transition temperature of the polyester resin, more preferably 15 from the viewpoint of improving the fusing property of the aggregated particles and improving the productivity of the toner. ℃ higher than the temperature, more preferably higher than 20 ℃ higher than the temperature, and higher than the glass transition temperature of the polyester resin, preferably less than 50 ℃ higher temperature, more preferably less than 40 ℃ higher temperature, more preferably higher by 30 ℃ Below temperature.
Specifically, it is preferably 70 ° C or higher, more preferably 75 ° C or higher, and preferably 100 ° C or lower, more preferably 90 ° C or lower. The stirring speed is preferably a speed at which the aggregated particles do not settle.

  In addition, when using an aggregation terminator, it is preferable to use a surfactant as the aggregation terminator, and it is more preferable to use an anionic surfactant. As the anionic surfactant, one or more selected from alkyl ether sulfates, alkyl sulfates, and linear alkylbenzene sulfonates are preferable, and alkyl ether sulfates are more preferable.

≪Post-processing process≫
The toner used in the present invention can be suitably obtained by subjecting the fused particles obtained in the above step to a solid-liquid separation step such as filtration, a washing step, and a drying step as appropriate.
In the washing step, it is preferable to completely remove the added nonionic surfactant by washing, and washing with an aqueous solution below the cloud point of the nonionic surfactant is preferred. The washing is preferably performed a plurality of times.
In the drying step, any method such as a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be employed. The water content after drying of the toner is preferably adjusted to 1.5% by mass or less, more preferably 1.0% by mass or less from the viewpoint of chargeability.
Further, an external additive may be added for the purpose of improving fluidity. Examples of the external additive include silica fine particles whose surface is hydrophobized, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, and inorganic fine particles such as carbon black; polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin, and the like. Fine particles can be used.

The number average particle diameter of the external additive is preferably 4 nm or more, more preferably 8 nm or more, still more preferably 12 nm or more, and preferably 200 nm or less, more preferably 50 nm or less, from the viewpoint of toner fluidity. More preferably, it is 40 nm or less.
When the external additive is added, the addition amount is preferably 0 with respect to 100 parts by mass of the toner particles before the treatment with the external additive from the viewpoint of improving the fluidity of the toner and the environmental stability of the charge degree. .1 part by mass or more, more preferably 0.5 part by mass or more, further preferably 1 part by mass or more, and preferably 5 parts by mass or less, more preferably 4 parts by mass or less, still more preferably 3 parts by mass or less. It is.

The toner production method used in the present invention preferably includes the following steps 1 to 3.
Step 1: In the presence of the wax, the polyvalent carboxylic acid component and the alcohol component containing the polyhydric alcohol and sterol are polycondensed to contain 5% by mass to 35% by mass of a structural unit derived from sterol. Step of obtaining a mixture containing polyester resin and wax to be processed Step 2: To the binder resin composition containing the mixture obtained in Step 1, an aqueous medium is added, phase inversion emulsification is performed, and the binder resin is obtained. Step of obtaining an aqueous dispersion of the composition Step 3: Step of agglomerating and fusing the aqueous dispersion obtained in Step 2

[Step 1]
In step 1, in the presence of the wax, the polyvalent carboxylic acid component and the alcohol component containing the polyhydric alcohol and sterol are polycondensed, and the structural unit derived from sterol is 5% by mass to 35% by mass. This is a step of obtaining a mixture containing a polyester-based resin and a wax.
The amount of the wax added in step 1 is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and still more preferably 8 parts by mass or more with respect to a total of 100 parts by mass of the polyvalent carboxylic acid component and the alcohol component. Yes, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 15 parts by mass or less.

≪Softening point≫
The softening point of the mixture containing the polyester-based resin and the wax obtained in step 1 is preferably 80 ° C. or higher, more preferably 90 ° C., from the viewpoints of minimum fixing temperature, heat-resistant storage stability, and adhesion to a polyolefin film. More preferably, the temperature is 100 ° C. or higher, and preferably 130 ° C. or lower, more preferably 120 ° C. or lower, and still more preferably 110 ° C. or lower.
≪Glass transition temperature≫
The glass transition temperature of the mixture containing the polyester-based resin and the wax is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and still more preferably, from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film. Is 50 ° C. or higher, and preferably 80 ° C. or lower, more preferably 70 ° C. or lower, and still more preferably 60 ° C. or lower.
≪Acid value≫
The acid value of the mixture containing the polyester resin and the wax is preferably 4 mg KOH / g or more, more preferably 6 mg KOH / g or more, more preferably from the viewpoint of the minimum fixing temperature, heat resistant storage stability, and adhesion to the polyolefin film. The amount is preferably 8 mgKOH / g or more, and preferably 25 mgKOH / g or less, more preferably 20 mgKOH / g or less, and further preferably 15 mgKOH / g or less.

[Step 2]
Step 2 is a step of adding an aqueous medium to the binder resin composition containing the mixture obtained in Step 1 and performing phase inversion emulsification to obtain an aqueous dispersion of the binder resin composition.
The conditions for phase inversion emulsification in step 2 are the same as the conditions for phase inversion emulsification in step I, and the preferred embodiments are also the same.
That is, first, a mixture containing a polyester-based resin and a wax, a surfactant added as necessary, and other optional components are dissolved in an organic solvent, and the polyester-based resin, wax and optional components are contained. An organic solvent solution of the binder resin composition is obtained, and then an aqueous dispersion can be obtained by phase inversion emulsification under the same conditions as in Step I.

[Step 3]
Step 3 is a step of aggregating and fusing the aqueous dispersion obtained in Step 2.
Step 3 is the same as Step II, and the preferred embodiment is also the same.

<Transfer process>
The transfer step is a step of transferring the toner image formed on the photoreceptor to a recording medium.
As the transfer process, a known method can be applied, and a corona transfer method in which corona ions are applied to the back side of the recording medium, and a conductive roller having a voltage applied to the back side of the recording medium is pressed to form transfer electrolysis by a voltage. A roller transfer method, a dielectric belt transfer method that also serves to convey a recording medium, and the like can be applied.

(recoding media)
The recording medium used in the image forming method of the present invention is a polyolefin film from the viewpoint of adhesion to the toner used in the present invention. There is no restriction | limiting in particular as a polyolefin film, A polyethylene film, a polypropylene film, etc. which can be obtained commercially can be used. The recording medium should just be a polyolefin film, and the other polymer film, for example, a polyethylene terephthalate (PET) film, may be pasted on the back surface. The polyolefin film may be a polymer alloy mixed with another polymer. In that case, the content of the polyolefin is 50% by mass or more, and preferably 80% by mass or more.
The polyolefin film may be combined with an inorganic material as long as the effects of the present invention are not impaired.
In the image forming method of the present invention, since the sterol group of the toner has a high affinity and easily adheres to a polyolefin film having a hydrophobic surface, an image having excellent adhesion to the polyolefin film is obtained.

<Fixing process>
The fixing step is a step of fixing the transferred toner image on the recording medium. The fixing step is not particularly limited, and can be performed using a known fixing device such as an oven fixing device or a heat roll fixing device.

[Aqueous dispersion of binder resin composition and method for producing toner for electrophotography]
The method for producing an aqueous dispersion of the binder resin composition of the present invention is a method for producing an aqueous dispersion of the binder resin composition contained in the toner used in the image forming method of the present invention. including.
Step 1: Polyester system containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and sterol in the presence of wax. Step of obtaining a mixture containing resin and wax Step 2: An aqueous medium is added to the binder resin composition containing the mixture obtained in Step 1, and phase inversion emulsification is performed. Step of Obtaining Aqueous Dispersion Further, the electrophotographic toner production method of the present invention is a toner production method used in the image forming method of the present invention. In addition to the above steps 1 and 2, the following step 3 is further performed. Including.
Step 3: Step of aggregating and fusing the aqueous dispersion obtained in Step 2 Obtained from the toner obtained by the production method of the present invention and the aqueous dispersion of the binder resin composition obtained by the production method of the present invention The toner contains a polyester-based resin containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol.
The sterol is bonded to the terminal of the polyester, and the polyester resin becomes a high molecular weight in a pseudo manner due to the interaction between the sterol groups. Therefore, it is considered that the heat resistant storage stability of the toner is improved.
On the other hand, since sterols have a property of sharp melting (sharp melt properties), the interaction between sterol groups contributing to the above-described pseudo high molecular weight rapidly weakens near the fixing temperature. The toner is considered to be excellent in low-temperature fixability.
Furthermore, since the sterol group has high hydrophobicity, the polyester resin having the sterol group and the polyolefin film having a hydrophobic surface have high affinity and are easy to adhere to each other, so that an image having excellent adhesion to the polyolefin film is obtained. It is thought that.
Steps 1 to 3 in the method for producing an aqueous dispersion of a binder resin composition and an electrophotographic toner are the same as steps 1 to 3 in the method for producing a toner used in the image forming method of the present invention. The preferred embodiment is also the same.

  The properties of the binder resin, binder resin particles, toner, etc. were measured and evaluated by the following methods.

[Acid Value of Binder Resin and Mixture Containing Binder Resin and Wax]
The acid value of the binder resin was measured based on the method of JIS K 0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K 0070 to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Softening point and glass transition temperature of binder resin and mixture containing binder resin and wax]
(1) Softening point 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. Extruded from a nozzle of 1 mm length 1 mm. 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.
(2) Maximum endothermic peak temperature Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), it is 0 ° C. at a temperature decreasing rate of 10 ° C./min from room temperature (20 ° C.). The sample cooled to 0 ° C. was allowed to stand for 1 minute, and then measured while heating up to 180 ° C. at a heating rate of 10 ° C./min. Of the endothermic peaks observed, the peak temperature on the highest temperature side was defined as the maximum endothermic peak temperature.
(3) Glass transition temperature Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of a sample is weighed into an aluminum pan, and 200 ° C. The temperature was raised to 0 ° C. from the temperature at a temperature drop rate of 10 ° C./min. Next, the measurement was performed while increasing the temperature to 150 ° C. at a temperature increase rate of 10 ° C./min. The glass transition temperature was defined as the temperature at the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent indicating the maximum slope from the peak rising portion to the peak apex.

[Volume Median Particle Size (D ₅₀ ) of Toner and Aggregated Particles]
The volume median particle size of the aggregated particles was measured as follows.
・ Measuring machine: "Coulter Multisizer III" (Beckman Coulter, Inc.)
・ Aperture diameter: 50μm
・ Analysis software: “Multisizer III version 3.51” (manufactured by Beckman Coulter)
・ Electrolyte: “Isoton II” (Beckman Coulter, Inc.)
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 sample (converted to solid content) 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 for 1 minute with an ultrasonic disperser. A sample dispersion was prepared by dispersing.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolytic solution to adjust the particle size of 30,000 particles to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured and the particle size distribution thereof. From this, the volume median particle size (D ₅₀ ) was determined.

[Volume Median Particle Size (D ₅₀ ) of Binder Resin Particles, Colorant Fine Particles, Charge Control Agent Fine Particles]
(1) Measuring apparatus: Laser diffraction type 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 ) was measured at a concentration at which the absorbance was in an appropriate range.

[Solid content concentration of aqueous dispersion of colorant dispersion, charge control agent dispersion, binder resin composition]
Using an infrared moisture meter “FD-230” (manufactured by Kett Science Laboratory Co., Ltd.), 5 g of the sample was subjected to a drying temperature of 150 ° C. and a measurement mode of 96 (monitoring time 2.5 minutes / variation width 0.05%). The sample was dried and the moisture content (% by mass) of the sample was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (mass%) = 100-sample moisture (mass%)

[Sterol reaction rate]
The ¹³ C-NMR spectrum of the binder resin was measured under the following conditions, and the proportion of sterol remaining as alcohol was calculated.
・ Measuring machine: Mercury-400 (Varian)
-Observation nucleus: ¹³ C
・ Resin sample: 1g
・ Measurement solvent: ₃ mL of CDCl 3
Magnetic field strength: 14.09637 [T] (600 [MHz])
・ Number of scans: 6400
-Relaxation time: 45 seconds

[Minimum fixing temperature (evaluation of low-temperature fixing property)]
The toner was mounted on an apparatus in which the fixing machine of the copying machine “AR-505” (manufactured by Sharp Corporation) was improved so that fixing outside the apparatus was possible, and a printed matter was obtained in an unfixed state (printing area: 2 cm). × 12 cm, adhesion amount: 0.5 mg / cm ² ). After that, using a fixing machine (fixing speed 300 mm / sec) adjusted so that the total fixing pressure becomes 40 kgf, the fixing roll temperature is gradually increased from 80 ° C. to 240 ° C. by 5 ° C., and unfixed at each temperature. A fixing test of the printed matter in the state was performed. A cellophane adhesive tape “UNICEF Cellophane” (Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z1522) was attached to the image portion of the obtained printed matter, passed through a fixing roller set at 30 ° C., and then the tape was peeled off. . The optical reflection density before and after the tape was peeled was measured using a reflection densitometer “RD-915” (manufactured by Gretag Macbeth Co.), and the ratio between the two (after peeling / before sticking × 100) was initially 90%. The temperature of the fixing roller that exceeded the minimum fixing temperature. The lower the minimum fixing temperature, the better the low-temperature fixing property. For the fixing paper, “CopyBond SF-70NA” (manufactured by Sharp Corporation, 75 g / m ² ) was used.

[Concentration remaining rate (Evaluation of adhesion of polyethylene film)]
A toner was mounted on a copying machine “AR-505” (manufactured by Sharp Corporation), and an image was printed without fixing (printing area: 2 cm × 12 cm, adhesion amount: 0.5 mg / cm ² ). The unfixed image was fixed on the print medium at 160 ° C. and 400 mm / sec with the fixing machine of the copying machine. A polyethylene film (trade name: Novatec LL UF420, manufactured by Nippon Polyethylene Co., Ltd.) was used as the print medium. After attaching cellophane tape made by Nichiban Co., Ltd. to the printed surface at 20N, the tape was peeled off manually, and the reflection density of the part where the tape was attached before and after peeling was measured using a spectral color difference meter (trade name) : NF777CE, manufactured by Nippon Denshoku Industries Co., Ltd.) From this measured value, the adhesion between the toner image and the polyethylene film was evaluated by the residual concentration rate shown in the following formula. The higher the residual concentration rate, the better the image adhesion to the polyethylene film.
Concentration residual ratio (%) = (reflection density after peeling / reflection density before pasting) × 100

[Aggregability under high temperature and high humidity (evaluation of heat-resistant storage stability of toner)]
A 25 mL container (diameter: about 3 cm) was charged with 5 g of toner and allowed to stand for 84 hours in an environment of temperature 50 ° C. and humidity 75%. The degree of occurrence of toner aggregation was visually observed every 12 hours, and heat resistant storage stability was evaluated according to the following evaluation criteria. The longer the time during which no aggregation is observed, the better the heat resistant storage stability.
(Evaluation criteria)
A: Aggregation is not observed after 60 hours, but aggregation is observed after 84 hours.
B: Aggregation is not observed after 48 hours, but aggregation is observed after 60 hours.
C: Aggregation is not observed after 36 hours, but aggregation is observed after 48 hours.
D: Aggregation is not observed after 24 hours, but aggregation is observed after 36 hours.
E: Aggregation is observed after 24 hours.

Production Example 1
(Production of polyester resin A)
Raw material monomers other than fumaric acid and trimellitic anhydride shown in Table 1, wax (paraffin wax “HNP-9”, manufactured by Nippon Seiwa Co., Ltd., melting point: 75 ° C.), esterification catalyst and esterification promoter , Put into a 10 liter four-necked flask equipped with a thermometer, a stainless steel stirring bar, a flow-down condenser and a nitrogen inlet tube, and heated up to 235 ° C. over 2 hours in a mantle heater in a nitrogen atmosphere. . Thereafter, the reaction was carried out at 235 ° C. and 8 kPa for 1 hour. Then, it cooled to 180 degreeC, 4-t-butylcatechol which is a radical polymerization inhibitor, fumaric acid, and trimellitic acid anhydride were added, and it heated up to 210 degreeC over 2 hours. Then, after reacting at 210 ° C. for 1 hour, the reaction was performed at 40 kPa until the softening point shown in Table 1 was reached, thereby obtaining a mixture containing polyester resin A and wax.

Production Example 2
(Production of polyester resin B)
BPA-PO shown in Table 1, half amount of collagenol (817 g), wax (paraffin wax “HNP-9”, manufactured by Nippon Seiwa Co., Ltd., melting point: 75 ° C.), terephthalic acid, esterification catalyst and esterification promoter , Put into a 10 liter four-necked flask equipped with a thermometer, a stainless steel stirring bar, a flow-down condenser and a nitrogen inlet tube, and heated up to 235 ° C. over 2 hours in a mantle heater in a nitrogen atmosphere. . Thereafter, the reaction was carried out at 235 ° C. and 8 kPa for 1 hour. Then, it cooled to 180 degreeC, and added 4-t-butylcatechol which is a radical polymerization inhibitor, the remaining corelterol (817g), fumaric acid, and trimellitic anhydride, and heated up to 210 degreeC over 2 hours. . Then, after reacting at 210 ° C. for 1 hour, the reaction was performed at 40 kPa until the softening point shown in Table 1 was reached, thereby obtaining a mixture containing polyester resin B and wax.

Production Examples 3, 4, 6-8
(Production of polyester resins C, D, F to H)
In Production Example 1, except that the raw material composition was changed as shown in Table 1, the reaction was carried out in the same manner as in Production Example 1 to obtain a mixture containing polyester resins C, D, F to H and wax.

Production Example 5
(Manufacture of polyester resin E)
In Production Example 1, a reaction was carried out in the same manner as in Production Example 1 except that no wax was added to obtain a polyester resin E. In addition, the polyester resin E was used in the aspect which throws in a wax at the time of subsequent emulsification.

[Production of colorant dispersion]
Production Example 9
50 g of copper phthalocyanine “ECB-301” (manufactured by Dainichi Seika Kogyo Co., Ltd.), 5 g of nonionic surfactant “Emulgen 150” (polyoxyethylene lauryl ether, manufactured by Kao Corporation) and 200 g of ion-exchanged water are mixed. A colorant dispersion containing fine colorant particles was obtained by dispersing for 10 minutes using a homogenizer. The volume median particle size (D ₅₀ ) of the colorant fine particles was 120 nm, and the solid content concentration was 22% by mass.

[Production of charge control agent dispersion]
Production Example 10
50 g of a salicylic acid compound “Bontron E-84” (made by Orient Chemical Co., Ltd.) as a charge control agent, 5 g of “Emulgen 150” (made by Kao Corporation) and 200 g of ion-exchanged water are mixed as a nonionic surfactant, Glass beads were used and dispersed for 10 minutes using a sand grinder to obtain a charge control agent dispersion liquid containing charge control agent fine particles. The volume median particle size (D ₅₀ ) of the charge control agent fine particles was 400 nm, and the solid content concentration was 22% by mass.

[Production of aqueous dispersion of binder resin composition]
Example 1
(Production of aqueous dispersion 1)
A 3 L container equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen introduction tube was charged with 150 g of a binder resin shown in Table 2 and 45 g of methyl ethyl ketone (hereinafter also referred to as “MEK”) at 73 ° C. For 2 hours. The obtained solution was neutralized by adding a 5% by mass aqueous sodium hydroxide solution to a degree of neutralization of 40 mol% with respect to the acid value of the polyester resin, and stirred for 30 minutes. Thereafter, 675 g of ion-exchanged water was added over 77 minutes while stirring at 280 r / min (peripheral speed 88 m / min) while maintaining the temperature at 30 ° C. Subsequently, after heating up to 50 degreeC over 30 minutes, MEK was distilled off under pressure reduction. Thereafter, the aqueous dispersion was cooled to 30 ° C. while stirring at 250 r / min (peripheral speed 88 m / min), and then an anionic surfactant “Emar E27C” (polyoxyethylene lauryl ether sodium sulfate, manufactured by Kao Corporation). 16.7 g) was mixed and completely dissolved. Thereafter, the solid content concentration of the dispersion was measured, and ion-exchanged water was added so as to be 20% by mass to obtain an aqueous dispersion 1 of the binder resin composition.

(Manufacture of toner)
300 g of the aqueous dispersion 1 of the binder resin composition obtained above, 8 g of the colorant dispersion, 2 g of the charge control agent dispersion and 52 g of deionized water are placed in a 2 L container, and 100 r with an anchor type stirrer. 150 g of a 0.1% by mass calcium chloride aqueous solution was added dropwise at 30 ° C. over 30 minutes with stirring at a rate of 30 minutes / minute (peripheral speed 31 m / minute). Thereafter, the temperature was raised to 50 ° C. while stirring, and kept at 50 ° C. until the volume median particle size became 5 μm. The volume median particle size reached 5 μm after 3 hours. Thereafter, a dilute solution obtained by diluting 4.2 g of anionic surfactant “Emar E27C” (manufactured by Kao Corporation, solid content: 28% by mass) with 37 g of deionized water was added as an aggregation terminator. Next, the temperature was raised to 80 ° C., and the temperature was maintained at 80 ° C. for 1 hour from the time when the temperature reached 80 ° C., and then the heating was terminated. As a result, fused particles were formed, and then slowly cooled to 20 ° C., filtered through a 150 mesh (mesh 150 μm) wire mesh, suction filtered, and washed and dried to obtain toner particles. .

  Hydrophobic silica “NAX-50” (manufactured by Nippon Aerosil Co., Ltd., number average particle diameter 40 nm) 1.0 part by mass, hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) A 10 L Henschel mixer equipped with ST and A0 stirring blades (number average particle diameter 16 nm) 0.6 parts by mass, titanium oxide “JMT-150IB” (manufactured by Teika Co., Ltd., number average particle diameter 15 nm) Nippon Coke Kogyo Co., Ltd.) and stirred at 3000 rpm for 2 minutes to obtain a toner. Table 2 shows the evaluation results of the toner.

Examples 2 to 4, 6 and Comparative Examples 1 and 2
(Production of aqueous dispersions 2-4, 6, 9, 10)
Aqueous dispersions 2 to 4, 6, 9, and 10 were obtained in the same manner as in Example 1 except that the binder resin was changed as shown in Table 2 in Example 1. The physical properties are shown in Table 2.
(Manufacture of toner)
A toner was obtained in the same manner as in Example 1 except that the aqueous dispersion 1 was changed to the aqueous dispersions 2 to 4, 6, 9, and 10 obtained above in Example 1. Table 2 shows the evaluation results of the toner.

Example 5
(Production of aqueous dispersion 5)
Into a 3 L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen introduction tube, 120 g of binder resin shown in Table 2, 30 g of wax and 45 g of MEK were charged and dissolved at 73 ° C. over 2 hours. I let you. The obtained solution was neutralized by adding a 5% by mass aqueous sodium hydroxide solution so that the neutralization degree was 100 mol% with respect to the acid value of the polyester resin, and stirred for 30 minutes. Thereafter, an aqueous dispersion 5 was obtained in the same manner as in Example 1. The physical properties are shown in Table 2.
(Manufacture of toner)
In Example 1, a toner was obtained in the same manner as in Example 1 except that the aqueous dispersion 1 was changed to the aqueous dispersion 5 obtained above. Table 2 shows the evaluation results of the toner.

Example 7
(Manufacture of toner)
To 900 g of ion-exchanged water heated to 60 ° C., 3 g of tricalcium phosphate (manufactured by Matsuo Pharmaceutical Co., Ltd.) is added, and using a TK homomixer (manufactured by PRIMIX Corporation) at 10,000 r / min. Stir to prepare an aqueous medium.
Meanwhile, 150 g of polyester resin A, 150 g of MEK, pigment blue 15: 3 10 g as a colorant, and 2 g of aluminum salicylate (trade name: Bontron E88, manufactured by Orient Chemical Co., Ltd.) as a charge control agent were added to a glass beaker and mixed. . The mixture was heated to 60 ° C. to uniformly dissolve solid components other than the colorant.
The polyester solution obtained above is added to the aqueous medium obtained above, and the suspension is obtained by stirring for 15 minutes with a TK homomixer (manufactured by Primix Co., Ltd.) at 60 ° C. under N ₂ gas flow. It was. The suspension was transferred to a separable flask and stirred at 70 ° C. and 150 r / min. Next, the temperature was raised to 80 ° C., and the remaining solvent was distilled off under reduced pressure. Thereafter, the mixture was cooled to 20 ° C. while being stirred, and washed and dried to obtain toner mother particles. Thereafter, a toner was obtained through an external addition step.

Example 8
(Manufacture of toner)
150 g of polyester resin A, 10 g of pigment blue 15: 3 as a colorant, and 2 g of aluminum salicylate (product name: Bontron E88, manufactured by Orient Chemical Co., Ltd.) as a charge control agent are mixed in a Henschel mixer and then rotated in the same direction. Using a twin screw extruder, melt kneading was performed at a roll rotation speed of 200 r / min and a heating temperature in the roll of 80 ° C. The obtained melt-kneaded product was cooled, coarsely pulverized, then pulverized with a jet mill, and classified to obtain toner base particles having a volume median particle size (D ₅₀ ) of 8 μm. Thereafter, a toner was obtained through an external addition step.

From Table 2, the toners of Examples 1 to 8 obtained from the aqueous dispersion obtained by the production method of the present invention are excellent in heat resistant storage stability, and the image forming method of the present invention using the toner has a low temperature. It is excellent in fixing property, and it can be seen that the obtained printed matter has excellent adhesion to the polyethylene film.
On the other hand, Comparative Example 1 in which the content of the structural unit derived from sterol in the polyester-based resin is less than 5% by mass was inferior in low-temperature fixability, heat resistant storage stability, and adhesiveness with a polyethylene film.
Moreover, the comparative example 2 whose content of the structural unit derived from sterol in a polyester-type resin is 35 mass% or more was inferior in heat-resistant storage stability.

Claims (7)

  A charging process for charging the photoconductor, an exposure process for exposing the photoconductor, a developing process for forming a toner image by attaching toner to the electrostatic latent image formed on the photoconductor, and a toner image formed An image forming method comprising a transfer step of transferring to a recording medium and a fixing step of fixing the transferred toner image to the recording medium, wherein the toner contains 5% by mass or more and 35% by mass or less of a structural unit derived from sterol. An image forming method comprising: a toner for electrophotography comprising a binder resin composition comprising a polyester resin and a wax, wherein the recording medium is a polyolefin film.   The image forming method according to claim 1, wherein the polyester resin is obtained by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and a sterol in the presence of a wax.   The image forming method according to claim 2, wherein a reaction rate of sterol in the polycondensation is 90% or more.   The image forming method according to claim 1, wherein the electrophotographic toner is obtained by aggregating and fusing an aqueous dispersion of the binder resin composition.   The image forming method according to claim 2, wherein the polyvalent carboxylic acid component includes an aromatic dicarboxylic acid compound and an aliphatic dicarboxylic acid compound having 4 to 8 carbon atoms. The manufacturing method of the aqueous dispersion of the binder resin composition of Claim 1 including the following processes 1 and 2.
Step 1: Polyester system containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and sterol in the presence of wax. Step of obtaining a mixture containing resin and wax Step 2: An aqueous medium is added to the binder resin composition containing the mixture obtained in Step 1, and phase inversion emulsification is performed. Step of obtaining an aqueous dispersion The method for producing an electrophotographic toner according to claim 1, comprising the following steps 1 to 3.
Step 1: Polyester system containing 5% by mass or more and 35% by mass or less of a structural unit derived from sterol by polycondensation of a polyvalent carboxylic acid component and an alcohol component containing a polyhydric alcohol and sterol in the presence of wax. Step of obtaining a mixture containing resin and wax Step 2: An aqueous medium is added to the binder resin composition containing the mixture obtained in Step 1, and phase inversion emulsification is performed. Step of obtaining aqueous dispersion Step 3: Step of aggregating and fusing the aqueous dispersion obtained in Step 2