JP5919693B2 - Toner for electrostatic image development - Google Patents

Description

  The present invention relates to an electrostatic charge image developing toner used for electrophotographic image formation.

  In recent years, in the field of electrostatic image developing toner (hereinafter, also simply referred to as “toner”), development of an electrophotographic apparatus suitable for the demand from the market and a toner usable for the development are rapidly growing. It is being advanced.

  For example, toner with high image quality is required to have a sharp particle size distribution because the reproducibility of minute dots is remarkably improved due to the uniform development behavior of each individual toner particle. For this reason, an emulsion polymerization aggregation method has been proposed as a production method capable of arbitrarily controlling the shape and particle size distribution of toner particles. In this method, a dispersion of colorant fine particles or, if necessary, a dispersion of wax fine particles is mixed with an emulsified dispersion of binder resin fine particles. The toner particles are obtained by aggregating the fine particles and further fusing the agglomerated particles by heating.

  Further, from the viewpoint of energy saving, development of a low-temperature fixing toner that can be fixed with less energy is in progress. In order to lower the fixing temperature of the toner, it is necessary to lower the melting temperature and melt viscosity of the binder resin. However, if a binder resin having a low glass transition point (Tg) or a binder resin having a low molecular weight is used to lower the melting temperature or melt viscosity of the binder resin, a new problem such as a decrease in heat-resistant storage property of the toner is caused. Occurs.

In order to solve this problem, a technique has been reported in which toner particles have a core-shell structure in order to satisfy both low-temperature fixability and heat-resistant storage stability (see, for example, Patent Document 1). That is, by forming a shell layer using fine particles with high softening point and high heat resistance on the surface of core particles excellent in low temperature fixability, a toner satisfying both low temperature fixability and heat storage stability is produced. can do. In particular, in the production of toner by the emulsion polymerization aggregation method, there is an advantage that such shape control can be easily performed.
However, in recent years, in the field of production printing, copying machines and printers have been increased in speed and compatible paper types have been expanded. Depending on the toner having a core-shell structure as disclosed in Patent Document 1, further low-temperature fixability and heat resistance can be achieved. It has become difficult to satisfy both storage requirements.

  In order to solve such a problem, a toner using a polyester resin as a material for the shell layer has been developed (for example, see Patent Document 2). Polyester resins have the advantage of being able to easily design a low softening point while maintaining a high glass transition point compared to styrene-acrylic resins. By using a polyester resin for the shell layer, low-temperature fixability and heat-resistant storage are possible. Toner with good properties can be obtained.

JP 2005-221933 A JP 2005-338548 A

  However, when a toner having a shell layer using a polyester resin is used, depending on the type of the image support, there is a problem that the image support is wound around the fixing roller, and sufficient fixing separation cannot be obtained. It has been found. Since this occurs remarkably when paper is used as the image support, it is considered that this is a problem caused by the high affinity between the paper and the polyester resin.

  The present invention has been made in consideration of the circumstances as described above, and the object thereof is excellent irrespective of the type of image support used while satisfying both the low-temperature fixability and the excellent heat-resistant storage stability. It is an object of the present invention to provide a toner for developing an electrostatic image that can provide fixing separation.

  As a result of intensive studies by the present inventors, by controlling the average dispersion diameter d of the wax in the toner particles within a specific range, it is possible to ensure fixing separation even when using an image support having a high affinity with the polyester resin. And the present invention has been completed.

The electrostatic charge image developing toner of the present invention is a toner particle in which a shell layer containing a polyester resin is formed on the surface of a core particle in which at least a wax is dispersed in a core resin containing a styrene-acrylic resin. An electrostatic charge image developing toner comprising:
The average dispersion diameter d of the wax in the core particles is 0.25 to 1.00 μm,
The wax is only microcrystalline wax,
The polyester resin contained in the shell layer is a styrene-acrylic modified polyester resin in which a styrene-acrylic polymer segment is bonded to an end of a polyester segment,
The content ratio of the styrene-acrylic polymer segment in the styrene-acrylic modified polyester resin is 5% by mass or more and 30% by mass or less,
In the structural unit derived from the polyvalent carboxylic acid monomer constituting the polyester segment of the styrene-acrylic modified polyester resin, the content ratio of the structural unit derived from the aliphatic unsaturated dicarboxylic acid is 25 mol% or more and 75 mol% or less. It is characterized by that.

In the electrostatic image developing toner of the present invention, the structural unit derived from the aliphatic unsaturated dicarboxylic acid in the structural unit derived from the polyvalent carboxylic acid monomer constituting the polyester segment of the styrene-acryl-modified polyester resin. The ratio is preferably 30 mol% or more and 60 mol% or less .

  In the electrostatic charge image developing toner of the present invention, the core resin preferably contains a polyester resin.

  In the electrostatic image developing toner of the present invention, the polyester resin contained in the core resin is preferably the same as the polyester resin contained in the shell layer.

In the electrostatic image developing toner of the present invention, the polyester resin contained in the core resin is a styrene-acrylic modified polyester resin in which a styrene-acrylic polymer segment is bonded to the end of the polyester segment. And
The content ratio of the styrene-acrylic polymer segment in the styrene-acrylic modified polyester resin is preferably 5% by mass or more and 30% by mass or less.

Furthermore, in the electrostatic image developing toner of the present invention, the structural unit derived from the aliphatic unsaturated dicarboxylic acid is preferably a structural unit derived from the one represented by the following general formula (A).
General formula (A): HOOC- (CR < ¹ > = CR _< ² _> ) _n- COOH
[Wherein, R ¹ and R ² are a hydrogen atom, a methyl group or an ethyl group, and may be the same or different from each other. n is an integer of 1 or 2. ]

  According to the toner for developing an electrostatic charge image of the present invention, since it has a structure in which a shell layer containing a polyester resin is formed on the surface of a core particle containing a styrene-acrylic resin, a sufficiently low temperature is basically sufficient. Fixability and excellent heat storage stability are obtained, and furthermore, since the wax is dispersed in a specific range of dispersion diameter in the toner particles, sufficient fixing separation is obtained regardless of the type of image support used.

  Hereinafter, the present invention will be specifically described.

〔toner〕
The toner of the present invention comprises toner particles in which a shell layer containing a polyester resin is formed on the surface of core particles in which a wax is dispersed in a core resin containing at least a styrene-acrylic resin. . And the average dispersion diameter (hereinafter also referred to as “wax dispersion diameter”) d of the wax in the core particles is 0.25 to 1.00 μm, preferably 0.25 to 0.50 μm.

  When the wax dispersion diameter d in the core particles is in the above range, sufficient fixing separation property can be obtained, and occurrence of a phenomenon such as wrapping at the time of fixing can be suppressed. On the other hand, when the wax dispersion diameter d exceeds 1.00 μm, since the exudation of the wax becomes insufficient, sufficient fixing and separation properties cannot be obtained. Further, it is difficult to produce a toner having a wax dispersion diameter d of less than 0.25 μm.

The wax dispersion diameter d is measured as follows.
Specifically, first, toner particles are embedded in a liquid or semi-cured epoxy resin and cured under conditions of 60 ° C. for 24 hours, and then the resulting cured product is used with a microtome equipped with diamond teeth. By cutting out the flat surface, the cross section is smoothed, and a block in which the particle cross section can be observed is produced as a measurement sample. Next, using a transmission microscope “JEM-2010F” (manufactured by JEOL Ltd.), a cross-sectional photograph of a particle at a magnification of 10,000 times was taken by STEM measurement, and 1,000 wax dispersions randomly selected The diameter was measured as the ferret diameter in the horizontal direction, and the average was calculated as the wax dispersion diameter d.

〔wax〕
Examples of the wax include low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, hydrocarbon waxes such as paraffin wax, carnauba wax, pentaerythritol behenate, behenyl behenate, Examples thereof include ester waxes such as acid behenyl, and these may be used singly or in combination of two or more, but it is particularly preferable to use only microcrystalline wax.
It is preferable to use a wax having a melting point of 50 to 95 ° C.

The wax content is preferably 4 to 15% by mass, more preferably 7 to 8% by mass, based on the total amount of the core resin.
When the content ratio of the wax is in the above range, the fixing and separating property can be reliably obtained regardless of the type of the image support used for image formation. On the other hand, when the content ratio of the wax is too small, there is a possibility that sufficient fixing separation property cannot be obtained. Further, when the wax content is excessive, the wax adheres to the fixing member, which may cause image memory.

The wax dispersion diameter d can be controlled by selecting the wax type. Specifically, when the wax contained is a hydrocarbon wax, the wax dispersion diameter d tends to be small, and when it is an ester wax, the wax dispersion diameter d tends to be large.
Further, when the toner of the present invention is produced by the emulsion polymerization aggregation method described later, the polyester resin is used as a fine particle that forms the core particle at the time of forming the core particle by adjusting the heating rate during the formation of the core particle. It can also be controlled by adding fine particles.
By adding the polyester resin fine particles in this way, the polyester resin fine particles and the wax are incompatible with each other, so that the coalescence of the wax can be prevented, and therefore the wax dispersion diameter d in the obtained toner is controlled to be small. be able to. This effect is more easily obtained when the wax contained is a hydrocarbon wax.

[Core resin]
The core resin that constitutes the core particles constitutes the binder resin together with the resin that constitutes the shell layer (hereinafter also referred to as “shell resin”) in the toner particles. The core resin may include, in addition to the styrene-acrylic resin, a resin conventionally used as a core resin for an electrophotographic toner. As such other resin, a polyester resin is preferable. A styrene-acrylic modified polyester resin in which a styrene-acrylic polymer segment is bonded to the terminal of the polyester segment described above is preferable.
When the core resin contains a polyester resin, the polyester resin contained in the core resin is preferably the same as the polyester resin contained in the shell layer. In particular, both of them are styrene-acryl modified. A polyester resin is preferred.
The same thing as the polyester resin contained in a shell layer means that the polymerization method and the kind and quantity of the monomer used for superposition | polymerization are the same as the polyester resin contained in a shell layer.

When the polyester resin is contained in the core resin, the wax dispersion diameter d in the toner particles is within the specific range. Moreover, since the affinity with the polyester resin constituting the shell layer is enhanced, it is possible to form a shell layer having a more uniform film thickness and a smooth surface while being a thin layer.
Moreover, when the said polyester resin is a styrene-acryl modified polyester resin, the effect that affinity with the styrene-acrylic resin which comprises core resin improves is acquired.
Moreover, when the said polyester resin is the same as the polyester resin contained in a shell layer, the effect that the affinity of a core particle and a shell layer is raised more is acquired.
Furthermore, when the polyester resin is a styrene-acrylic modified polyester resin and is the same as the polyester resin contained in the shell layer, there is an effect that the affinity between the core resins and between the core particles and the shell layer is increased. can get.

[Styrene-acrylic resin]
The styrene-acrylic resin contained in the core resin is obtained from a polymerizable monomer containing an aromatic vinyl monomer and a (meth) acrylic acid ester monomer.
Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples include 4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof.
These aromatic vinyl monomers can be used alone or in combination of two or more.
Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.
These (meth) acrylic acid ester monomers can be used alone or in combination of two or more.

As the polymerizable monomer, together with the above aromatic vinyl monomer and (meth) acrylic acid ester monomer, acrylic acid, methacrylic acid, maleic anhydride, vinyl acetate, acrylamide, methacrylamide, acrylonitrile, Ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone, butadiene and the like can also be used.
Moreover, a polyfunctional vinyl-type monomer can also be used as a polymerizable monomer with said aromatic vinyl monomer and (meth) acrylic acid ester monomer. Examples of the polyfunctional vinyl monomer include diacrylates such as ethylene glycol, propylene glycol, butylene glycol, and hexylene glycol; dimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane; Examples include trimethacrylate.
The ratio (copolymerization ratio) of the polyfunctional vinyl monomer in the entire polymerizable monomer for obtaining the core resin is usually 0.001 to 5% by mass, preferably 0.003 to 2% by mass, More preferably, it is 0.01-1 mass%.
By using a polyfunctional vinyl monomer, a gel component insoluble in tetrahydrofuran is generated. The gel component is preferably 40% by mass or less, more preferably 20% by mass or less of the entire core resin. is there.

  The content ratio of the styrene-acrylic resin in the core resin is preferably 50 to 100% by mass and more preferably 70 to 95% by mass in 100% by mass of the core resin.

[Shell resin]
The shell layer constituting the toner of the present invention is made of a shell resin containing a polyester resin. The shell resin constitutes the binder resin together with the core resin in the toner particles.
In particular, the polyester resin contained in the shell resin is preferably partly or wholly a styrene-acryl-modified polyester resin.
Examples of the resin that can be contained together with the polyester resin in the shell resin include styrene-acrylic resins and urethane resins.

By using a styrene-acryl-modified polyester resin as the shell resin constituting the toner, the following effects can be obtained.
That is, in general, the advantage of using a polyester resin as a binder resin in designing toner particles is that the polyester resin maintains a high glass transition point (Tg) as compared with a styrene-acrylic resin and is designed to have a low softening point. Is easy to do. That is, the polyester resin is a suitable resin for satisfying both low-temperature fixability and heat-resistant storage stability. And by introducing a styrene-acrylic polymer segment into the polyester resin used in the shell layer, the affinity of the core particle with the styrene-acrylic resin of the core particle while maintaining the high glass transition point and low softening point of the polyester resin As a result, a shell layer having a more uniform film thickness and a smooth surface can be formed while being a thin layer. Therefore, according to the toner of the present invention, both low-temperature fixability and heat-resistant storage stability are satisfied, and excellent chargeability is obtained. Further, since the shell layer is hardly peeled off, the toner is stirred in the developing device. As a result, sufficient resistance to crushing that is not crushed even when subjected to stress is obtained, and as a result, a high-quality image such as a high-speed machine can be obtained without causing image noise.

The content of the styrene-acrylic modified polyester resin in the shell resin is preferably 70 to 100% by mass and more preferably 90 to 100% by mass in 100% by mass of the shell resin.
When the content ratio of the styrene-acrylic modified polyester resin in the shell resin is less than 70% by mass, sufficient affinity between the core particles and the shell layer cannot be obtained, and a desired shell layer cannot be formed. Therefore, there is a possibility that sufficient heat storage stability, chargeability or crushing resistance may not be obtained.

[Styrene-acrylic modified polyester resin]
The styrene-acrylic modified polyester resin is obtained by bonding a styrene-acrylic polymer segment to the end of a polyester segment.
The content of the styrene-acrylic polymer segment in the styrene-acrylic modified polyester resin (hereinafter also referred to as “styrene-acrylic modification amount”) is preferably 5% by mass or more and 30% by mass or less, and particularly 5% by mass. % Or more and 20% by mass or less is preferable.
Specifically, the amount of styrene-acryl modification is the total mass of materials used for synthesizing the styrene-acryl modification polyester resin, that is, a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer that becomes a polyester segment, Aromatic vinyl based on the total mass of the aromatic vinyl monomer and (meth) acrylic acid ester monomer to be a styrene-acrylic polymer segment, and the total amount of both reactive monomers for bonding them. The ratio of the mass of a monomer and a (meth) acrylic acid ester monomer is said.

  When the amount of styrene-acrylic modification is in the above range, the affinity between the styrene-acrylic modified polyester resin and the core particles is properly controlled, and a thin shell layer with a more uniform thickness and a smooth layer can be obtained. Can be formed. On the other hand, when the amount of styrene-acryl modification is too small, a shell layer with a uniform film thickness cannot be formed, and the core particles are partially exposed. As a result, sufficient heat storage stability and chargeability are obtained. I can't get it. If the amount of styrene-acrylic modification is excessive, the styrene-acrylic modified polyester resin has a high softening point, so that sufficient low-temperature fixability cannot be obtained for the entire toner particles.

In the toner of the present invention, an aliphatic unsaturated dicarboxylic acid is used as a polyvalent carboxylic acid monomer to form a polyester segment of a styrene-acryl-modified polyester resin, and the aliphatic unsaturated dicarboxylic acid is added to the polyester segment. It is preferable that a structural unit derived from an acid is contained.
The aliphatic unsaturated dicarboxylic acid refers to a chain dicarboxylic acid having a vinylene group in the molecule.
According to the styrene-acryl-modified polyester resin having a structural unit derived from an aliphatic unsaturated dicarboxylic acid, it is possible to reliably form a smooth shell layer having a more uniform film thickness while being a thin layer.

The proportion of structural units derived from aliphatic unsaturated dicarboxylic acids in the structural units derived from polyvalent carboxylic acid monomers constituting the polyester segment of the styrene-acrylic modified polyester resin (hereinafter referred to as “specific unsaturated dicarboxylic acid-containing” The ratio is also preferably 25 mol% or more and 75 mol% or less, and more preferably 30 mol% or more and 60 mol% or less.
When the content ratio of the specific unsaturated dicarboxylic acid is within the above range, a smooth shell layer having a more uniform film thickness can be more reliably formed while being a thin layer. On the other hand, if the specific unsaturated dicarboxylic acid content is too small, sufficient heat-resistant storage stability and chargeability may not be obtained, and if the specific unsaturated dicarboxylic acid content is excessive, Sufficient chargeability may not be obtained.

The structural unit derived from the aliphatic unsaturated dicarboxylic acid is preferably a structural unit derived from one represented by the following general formula (A).
General formula (A): HOOC- (CR < ¹ > = CR _< ² _> ) _n- COOH
[Wherein, R ¹ and R ² are a hydrogen atom, a methyl group or an ethyl group, and may be the same or different from each other. n is an integer of 1 or 2. ]
By containing the structural unit derived from such an aliphatic unsaturated dicarboxylic acid, it is possible to more reliably form a smooth shell layer with a more uniform film thickness while being a thin layer.
This was emulsified by using a styrene-acryl-modified polyester resin having a structural unit derived from an aliphatic unsaturated dicarboxylic acid having a vinylene group, for example, when producing toner particles by an emulsion polymerization aggregation method described later. It is inferred that the aggregation of fine particles with the styrene-acryl-modified polyester resin at the time is improved, and the aggregation of the core particles to the surface proceeds uniformly. In addition, since the styrene-acryl-modified polyester resin having a structural unit derived from an aliphatic unsaturated dicarboxylic acid having a vinylene group has a high polarity, the toner particles are used, for example, by an emulsion polymerization aggregation method described later. This is also presumed that the polyester segment portion of the fine particles of the styrene-acrylic modified polyester resin to form the shell layer is easily oriented to the surface side in the aggregated particles.

[Production Method of Styrene-Acrylic Modified Polyester Resin]
As a method for producing the styrene-acrylic modified polyester resin, an existing general scheme can be used. Typical methods include the following three methods.
(A-1) A polyester segment is polymerized in advance, and both reactive monomers are reacted with the polyester segment, and an aromatic vinyl monomer and (meta) are formed to form a styrene-acrylic polymer segment. ) A method of forming a styrene-acrylic polymer segment by reacting an acrylate monomer.
(A-2) A polyvalent carboxylic acid monomer for polymerizing a styrene-acrylic polymer segment in advance, reacting the styrene-acrylic polymer segment with both reactive monomers, and further forming a polyester segment And a method of forming a polyester segment by reacting a polyhydric alcohol monomer.
(B) A method in which a polyester segment and a styrene-acrylic polymer segment are respectively polymerized in advance, and both are reacted with each other by reacting them with each other.
In this specification, the both reactive monomers are a group capable of reacting with a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer for forming a polyester segment of a styrene-acryl-modified polyester resin, and a polymerizable unsaturated group. And a monomer having

The method (A-1) will be specifically described.
(1) A mixing step of mixing an unmodified polyester resin, an aromatic vinyl monomer and a (meth) acrylic acid ester monomer, and both reactive monomers,
(2) A styrene-acrylic polymer segment can be formed at the end of the polyester segment by passing through a polymerization step of polymerizing the aromatic vinyl monomer and the (meth) acrylic acid ester monomer.

  In the mixing step (1), it is preferable to heat. The heating temperature may be within a range where unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer and both reactive monomers can be mixed. Since it is obtained and polymerization control becomes easy, it can be set to, for example, 80 to 120 ° C., more preferably 85 to 115 ° C., and further preferably 90 to 110 ° C.

  Among unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer and both reactive monomers, aromatic vinyl monomer and (meth) acrylic acid ester monomer The total proportion of the resin material used, that is, the total amount of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer when the total mass of the four members is 100% by mass. The ratio is 5% by mass or more and 30% by mass or less, and particularly preferably 5% by mass or more and 20% by mass or less.

  When the total ratio of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer to the total mass of the resin material used is within the above range, the styrene-acrylic modified polyester resin and the core particle The affinity is appropriately controlled, and a smooth shell layer can be formed with a more uniform film thickness while being a thin layer. On the other hand, when the ratio is too small, the resulting styrene-acryl-modified polyester resin cannot form a shell layer with a uniform film thickness, resulting in partial exposure of the core particles. Therefore, sufficient heat storage stability and chargeability cannot be obtained for the obtained toner. If the ratio is excessive, the resulting styrene-acryl-modified polyester resin has a high softening point, so that the resulting toner cannot obtain sufficient low-temperature fixability as a whole.

The relative proportion of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer is such that the glass transition point (Tg) calculated by the FOX formula represented by the following formula (A) is 35. It is preferable that the ratio is in the range of -80 ° C, preferably 40-60 ° C.
Formula (A): 1 / Tg = Σ (Wx / Tgx)
[In Formula (A), Wx is the weight fraction of monomer x, and Tgx is the glass transition point of the homopolymer of monomer x. ]
In the present specification, both reactive monomers are not used for calculation of the glass transition point.

  Among unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer, and both reactive monomers, the proportion of both reactive monomers used is the total mass of the resin material used, that is, The ratio of the two reactive monomers when the total mass of the four components is 100% by mass is 0.1% by mass or more and 5.0% by mass or less, and particularly 0.5% by mass or more and 3.0% by mass. The following is preferable.

[Aromatic vinyl monomers and (meth) acrylic acid ester monomers]
Examples of the aromatic vinyl monomer and (meth) acrylic acid ester monomer for forming the styrene-acrylic polymer segment include those listed above. The above aromatic vinyl monomers and (meth) acrylic acid ester monomers can be used singly or in combination of two or more.

  As an aromatic vinyl monomer and (meth) acrylic acid ester monomer for forming a styrene-acrylic polymer segment, styrene or a derivative thereof is used from the viewpoint of obtaining excellent chargeability and image quality characteristics. It is preferable to use a large amount. Specifically, the amount of styrene or a derivative thereof used is the total amount of monomers (aromatic vinyl monomer and (meth) acrylic ester single monomer used to form a styrene-acrylic polymer segment). It is preferable that it is 50 mass% or more in the body.

[Amotropic monomer]
As the both reactive monomers for forming a styrene-acrylic polymer segment, a group capable of reacting with a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer for forming a polyester segment, a polymerizable unsaturated group, Specifically, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, and the like can be used.

[Polyester resin]
The polyester resin used for producing the styrene-acrylic modified polyester resin according to the present invention is obtained by polycondensation reaction in the presence of an appropriate catalyst using a polyvalent carboxylic acid monomer (derivative) and a polyhydric alcohol monomer (derivative) as raw materials. It is manufactured.

  As polyvalent carboxylic acid monomer derivatives, alkyl esters, acid anhydrides and acid chlorides of polyvalent carboxylic acid monomers can be used. As polyhydric alcohol monomer derivatives, ester compounds of polyhydric alcohol monomers and hydroxycarboxylic acids are used. Can be used.

  Examples of the polyvalent carboxylic acid monomer include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid. Acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucoic acid, phthalic acid, Isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, Diphenylacetic acid, diphenyl-p, p'- Divalent carboxylic acids such as carboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenyl succinic acid; trimellitic acid, pyromellitic And divalent or higher carboxylic acids such as acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

As the polyvalent carboxylic acid monomer, an aliphatic unsaturated dicarboxylic acid such as fumaric acid, maleic acid or mesaconic acid is preferably used, and in particular, an aliphatic unsaturated dicarboxylic acid represented by the above general formula (A) is used. It is preferable.
By using the aliphatic unsaturated dicarboxylic acid, the obtained styrene-acryl-modified polyester resin can surely form a smooth shell layer with a more uniform film thickness while being a thin layer. . In particular, by using the aliphatic unsaturated dicarboxylic acid represented by the general formula (A), the obtained styrene-acryl-modified polyester resin is more surely a thin layer with a more uniform film thickness and A smooth shell layer can be formed.

The ratio of the aliphatic unsaturated dicarboxylic acid in the total polyvalent carboxylic acid monomer to be used is preferably 25 mol% or more and 75 mol% or less, and more preferably 30 mol% or more and 60 mol% or less.
When the ratio of the aliphatic unsaturated dicarboxylic acid used is in the above range, the obtained styrene-acryl-modified polyester resin is more surely a thin shell with a more uniform film thickness and a smooth shell layer. Can be formed. On the other hand, if the proportion of the aliphatic unsaturated dicarboxylic acid used is too small, sufficient heat-resistant storage stability and chargeability may not be obtained in the obtained toner, and the proportion of the aliphatic unsaturated dicarboxylic acid used is If it is excessive, sufficient chargeability may not be obtained for the obtained toner.

  Examples of the polyhydric alcohol monomer include ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, and the like. And trivalent or higher polyols such as glycerin, pentaerythritol, hexamethylol melamine, hexaethylol melamine, tetramethylol benzoguanamine, and tetraethylol benzoguanamine.

  The ratio of the polyhydric carboxylic acid monomer to the polyhydric alcohol monomer is preferably an equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] of the polyhydric alcohol monomer and the carboxyl group [COOH] of the polyhydric carboxylic acid. Is 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2.

  As the catalyst for synthesizing the polyester resin, various conventionally known catalysts can be used.

  The unmodified polyester resin for obtaining the styrene-acrylic modified polyester resin preferably has a glass transition point of 40 ° C. or higher and 70 ° C. or lower, more preferably 50 ° C. or higher and 65 ° C. or lower. When the glass transition point of the unmodified polyester resin is 40 ° C. or higher, the cohesive force in the high temperature region becomes appropriate for the polyester resin, and the occurrence of hot offset phenomenon during fixing is suppressed. Further, since the glass transition point of the unmodified polyester resin is 70 ° C. or less, sufficient melting can be obtained at the time of fixing, and a sufficient minimum fixing temperature can be ensured.

The unmodified polyester resin preferably has a weight average molecular weight (Mw) of 1,500 to 60,000, more preferably 3,000 to 40,000.
When the weight average molecular weight is 1,500 or more, a cohesive force suitable for the entire binder resin is obtained, and the occurrence of a hot offset phenomenon during fixing is suppressed. Further, when the weight average molecular weight is 60,000 or less, it is possible to obtain a sufficient melting and secure a minimum fixing temperature, while suppressing occurrence of a hot offset phenomenon during fixing. The

  The unmodified polyester resin has a partially branched structure or a crosslinked structure formed by selecting a carboxylic acid valence or an alcohol valence as a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer to be used. May be.

(Polymerization initiator)
In the polymerization step (2), it is preferable to carry out the polymerization in the presence of a radical polymerization initiator, and the timing of addition of the radical polymerization initiator is not particularly limited, but mixing is performed because radical polymerization can be easily controlled. It is preferably added after the step.

  Various known polymerization initiators are preferably used as the polymerization initiator. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, Lauroyl oxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert-hydroperoxide, performic acid-tert -Butyl, peracetic acid-tert-butyl, perbenzoic acid-tert-butyl, perphenylacetic acid-tert-butyl, permethoxyacetic acid-tert-butyl, per-N- (3-toluyl) palmitic acid-tert-butyl, etc. Peroxides; 2 2'-azobis (2-aminodipropane) hydrochloride, 2,2'-azobis- (2-aminodipropane) nitrate, 1,1'-azobis (1-methylbutyronitrile-3-sulfonic acid sodium salt) 4, 4'-azobis-4-cyanovaleric acid, poly (tetraethylene glycol-2,2'-azobisisobutyrate) and other azo compounds.

[Chain transfer agent]
In the polymerization step (2), a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight of the styrene-acrylic polymer segment. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans and mercapto fatty acid esters.
The chain transfer agent is preferably mixed with the resin material in the mixing step.

  The addition amount of the chain transfer agent varies depending on the molecular weight and molecular weight distribution of the desired styrene-acrylic polymer segment. Specifically, the aromatic vinyl monomer and the (meth) acrylate monomer, and It is preferable to add in the range of 0.1-5 mass% with respect to the total amount of both reactive monomers.

  The polymerization temperature in the polymerization step (2) is not particularly limited, and is appropriately selected within a range in which the polymerization between the aromatic vinyl monomer and the (meth) acrylic acid ester monomer and the bonding to the polyester resin proceed. be able to. For example, the polymerization temperature is preferably 85 ° C. or higher and 125 ° C. or lower, more preferably 90 ° C. or higher and 120 ° C. or lower, and further preferably 95 ° C. or higher and 115 ° C. or lower.

  In the production of the styrene-acrylic modified polyester resin, it is practically preferable that volatile organic substances from the emulsion such as the amount of residual monomer after the polymerization step are suppressed to 1,000 ppm or less, more preferably 500 ppm or less, Preferably it is 200 ppm or less.

The shell resin preferably has a glass transition point of 50 to 70 ° C. from the viewpoint of surely obtaining fixing properties such as low-temperature fixing property and fixing separation property, and heat resistance such as heat-resistant storage property and blocking resistance, More preferably, it is 50-65 degreeC, and it is preferable that a softening point is 80-110 degreeC.
The glass transition point and softening point of the shell resin are measured in the same manner as described above using a core resin as a measurement sample.

The content ratio of the shell resin in the binder resin constituting the toner is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass based on the total amount of the binder resin.
When the content ratio of the shell resin in the binder resin is excessively low, sufficient heat-resistant storage stability may not be obtained, and when the content ratio of the shell resin in the binder resin is excessively high, the temperature is sufficiently low. There is a possibility that the fixing property cannot be obtained.

[Colorant]
In the toner of the present invention, the core particles may contain a colorant.
As the colorant, carbon black, a magnetic material, a dye, a pigment, and the like can be arbitrarily used.
As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like can be used.
As the magnetic material, ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite can be used.
As the pigment, C.I. I. Pigment Red 2, 3, 5, 7, 15, 16, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 123, 139, 144, 149, 166, 177, 178, 208, 209, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 3, 9, 14, 17, 35, 36, 65, 74, 83, 93, 94, 98, 110, 111, 138, 139, 153, 155, 180, 181, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 15: 4, 60, and phthalocyanine pigments whose central metal is zinc, titanium, magnesium, or the like can be used, and a mixture thereof can also be used. As the dye, C.I. I. Solvent Red 1, 3, 14, 17, 17, 22, 22, 49, 51, 52, 58, 63, 87, 111, 122, 127, 128, 131, 145, 146, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 176, 179, pyrazolotriazole Azo dyes, pyrazolotriazole azomethine dyes, pyrazolone azo dyes, pyrazolone azomethine dyes, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures thereof can also be used.
The number average primary particle size of the colorant varies depending on the type, but is preferably about 10 to 200 nm.

  When the core particles are configured to contain a colorant, the content ratio of the colorant in the toner is preferably 1 to 30% by mass, more preferably 2 to 20% by mass with respect to the total amount of the binder resin. It is.

[Toner Production Method]
The toner of the present invention is formed by agglomerating and fusing core resin fine particles and colorant fine particles dispersed in an aqueous medium to form core particles, and aggregating and fusing shell resin fine particles on the surface of the core particles. The toner particles can be produced by an emulsion polymerization aggregation method. By producing the toner by the emulsion polymerization aggregation method, the wax dispersion diameter d can be easily controlled.

In the toner of the present invention, specifically showing an example of producing a toner containing a colorant by an emulsion polymerization aggregation method,
(1-1) A shell resin fine particle dispersion preparing step of forming a shell resin fine particle by a shell resin in an aqueous medium to prepare a dispersion in which the shell resin fine particle is dispersed;
(1-2) A wax-containing core resin fine particle dispersion preparing step for preparing a dispersion in which wax-containing core resin fine particles containing a wax and a core resin are dispersed in an aqueous medium.
(1-3) Colorant fine particle dispersion preparation step for preparing a dispersion in which colorant fine particles are dispersed in an aqueous medium.
(2) a core particle forming step of aggregating wax-containing core resin fine particles and colorant fine particles in an aqueous medium to form core particles;
(3) A shell in which shell resin fine particles are added to an aqueous medium in which core particles are dispersed to aggregate and fuse the shell resin fine particles on the surface of the core particles to form toner base particles having a core-shell structure. Conversion process,
(4) An aging step of adjusting the shape of the toner base particles by aging with thermal energy;
(5) A cleaning step of filtering the toner base particles from the dispersion system (aqueous medium) of the toner base particles, and removing the surfactant and the like from the toner base particles. (6) Drying for drying the toner base particles that have been cleaned. Process,
Consisting of, if necessary,
(7) An external additive addition step of adding an external additive to the dried toner base particles can be added.

(1-1) Shell resin fine particle dispersion preparation step In this shell resin fine particle dispersion preparation step, the dispersion of shell resin fine particles is an aqueous system to which a surfactant is added by, for example, an ultrasonic dispersion method or a bead mill dispersion method. It can be obtained by a direct dispersion method.

The average particle diameter of the shell resin fine particles obtained in the shell resin fine particle dispersion preparing step is preferably in the range of, for example, 50 to 500 nm in terms of volume-based median diameter.
The volume-based median diameter is measured using “UPA-150” (manufactured by Microtrack).

  In the present invention, the “aqueous medium” refers to a medium comprising 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

[Surfactant]
A dispersion stabilizer is preferably added to the aqueous medium in order to prevent aggregation of dispersed droplets.
As the dispersion stabilizer, various known surfactants such as a cationic surfactant, an anionic surfactant, and a nonionic surfactant can be used.
Specific examples of the cationic surfactant include dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl anonium bromide and the like.
Specific examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, norylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, styrylphenyl poly Examples thereof include oxyethylene ether and monodecanoyl sucrose.
Specific examples of the anionic surfactant include aliphatic soaps such as sodium stearate and sodium laurate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene (2) sodium lauryl ether sulfate and the like. it can.
The above surfactants can be used singly or in combination of two or more as desired.

(1-2) Wax-containing core resin fine particle dispersion preparation step In this wax-containing core resin fine particle dispersion preparation step, resin fine particles containing a wax and a core resin are formed, and this is provided for the core particle formation step. The
Specifically, the wax-containing core resin resin fine particles are used as a polymerizable monomer for forming the core resin in a water-based medium containing a surfactant having a critical micelle concentration (CMC) or less. In response, a monomer solution in which other toner components such as a charge control agent are dissolved or dispersed is added, and mechanical energy is applied at a temperature above the melting point of the wax to form droplets. A radical polymerization initiator is added to advance the polymerization reaction in the droplets. Note that an oil-soluble polymerization initiator may be contained in the droplet. In such a wax-containing core resin fine particle dispersion preparation step, mechanical energy is forcibly emulsified (formation of droplets) is essential. Examples of the means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin.

  The wax-containing core resin fine particles formed in the step of preparing the wax-containing core resin fine particle dispersion may have a structure of two or more layers made of resins having different compositions. In this case, an emulsion polymerization treatment according to a conventional method It is possible to employ a method in which a polymerization initiator and a polymerizable monomer are added to the dispersion of the first resin particles prepared by (first stage polymerization), and this system is polymerized (second stage polymerization). In this case, the wax may be contained in any layer, but in particular, in the case of a three-layer structure, the wax is preferably contained in the intermediate layer.

  When a surfactant is used in the wax-containing core resin fine particle dispersion preparation step, the same surfactant as the surfactant that can be used in the above-mentioned shell resin fine particle dispersion preparation step, for example, is used. Can be used.

In addition to the wax, the toner particles of the present invention may contain an internal additive such as a charge control agent or magnetic powder as necessary. Such an internal additive may be, for example, this wax-containing core. In the resin fine particle dispersion preparation step, it can be introduced into the toner particles by dissolving or dispersing in advance in a monomer solution for forming the core resin.
In addition, such an internal additive is prepared by separately preparing a dispersion of internal additive fine particles consisting of only the internal additive, and aggregating the internal additive fine particles together with the resin fine particles and the colorant fine particles in the core particle forming step. Although it can be introduced into the toner particles, it is preferable to adopt a method of introducing in advance in the step of preparing the wax-containing core resin fine particle dispersion.

(Charge control agent)
In addition, when a charge control agent is contained in the toner particles according to the present invention, various known charge control agents can be used.
As the charge control agent, various known compounds that can be dispersed in an aqueous medium can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, fourth compounds. Examples include quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
The content ratio of the charge control agent is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass with respect to the total amount of the core resin.

(Polymerization initiator)
As the polymerization initiator used in the step of preparing the wax-containing core resin fine particle dispersion, the same ones as described above can be used.

[Chain transfer agent]
In the step of preparing the wax-containing core resin fine particle dispersion, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the core resin. As the chain transfer agent, the same ones as described above can be used.

The average particle diameter of the core resin fine particles obtained in this wax-containing core resin fine particle dispersion preparation step is preferably in the range of, for example, 50 to 500 nm in terms of volume-based median diameter.
The volume-based median diameter is measured using “UPA-150” (manufactured by Microtrack).

(1-3) Colorant fine particle dispersion preparation step The colorant fine particle dispersion can be prepared by dispersing a colorant in an aqueous medium. The colorant dispersion treatment is preferably performed in a state where the surfactant concentration in the aqueous medium is not less than the critical micelle concentration (CMC) since the colorant is uniformly dispersed. Various known dispersers can be used as a disperser used for the dispersion treatment of the colorant.
Examples of the surfactant used include the same surfactants as those described above.

The dispersion diameter of the colorant fine particles in the colorant fine particle dispersion prepared in the colorant fine particle dispersion preparing step is preferably 10 to 300 nm in terms of volume-based median diameter.
The volume-based median diameter of the colorant fine particles in the colorant fine particle dispersion is measured with an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

  When a surfactant is used in this colorant fine particle dispersion preparation step, the same surfactant as the surfactant that can be used in the above-mentioned shell resin fine particle dispersion preparation step, for example, is used. Can be used.

  The colorant may be introduced into the toner particles by, for example, dissolving or dispersing in advance in the monomer solution for forming the core resin in the wax-containing core resin fine particle dispersion preparation step.

(2) Core particle forming step In the core particle forming step, fine particles of other toner constituent components such as a charge control agent can be aggregated together with the core resin fine particles and the colorant fine particles, if necessary.

  As a specific method for agglomerating and fusing the core resin fine particles and the colorant fine particles, a flocculant is added to an aqueous medium so as to have a critical aggregation concentration or higher, and then the glass transition point of the core resin fine particles or higher. Further, by heating the mixture to a temperature equal to or higher than the melting peak temperature (° C.) of the mixture, the salting out of the fine particles such as the core resin fine particles and the colorant fine particles proceeds, and at the same time, the fusion is proceeded in parallel to obtain desired particles In this method, the particle growth is stopped by adding a coagulation terminator when it has grown to the diameter, and further, heating is continued to control the particle shape as necessary.

  In this method, the time allowed to stand after adding the flocculant is as short as possible, and the temperature is not less than the glass transition point of the resin fine particles relating to the core resin and not less than the melting peak temperature (° C.) of the mixture. It is preferable to heat it. The reason for this is not clear, but depending on the standing time after salting out, the aggregation state of the particles may fluctuate and the particle size distribution may become unstable, and the surface properties of the fused particles may vary. This is because there is concern about the occurrence. The time until the temperature rise is preferably within 30 minutes, more preferably within 10 minutes. Moreover, as a temperature increase rate, 0.5 degreeC / min-1 degreeC / min are preferable. By adjusting the temperature increase rate, the wax dispersion diameter d in the obtained toner can be controlled. Furthermore, after the reaction system reaches a temperature equal to or higher than the glass transition point, it is important to continue the fusion by maintaining the temperature of the reaction system for a certain time. Thereby, the growth and fusion of the core particles can be effectively advanced, and the durability of the toner particles finally obtained can be improved.

[Flocculant]
The flocculant used in the core particle forming step is not particularly limited, but a material selected from metal salts is preferably used. Examples of the metal salt include monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; and trivalent metal salts such as iron and aluminum. Etc. Specific metal salts can include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, and the like. It is particularly preferable to use a divalent metal salt. These can be used individually by 1 type or in combination of 2 or more types.

  When using a surfactant in the core particle forming step, it is possible to use, for example, the same surfactant as the surfactant that can be used in the above-mentioned shell resin fine particle dispersion preparation step. it can.

As for the particle size of the core particles obtained in this core particle forming step, for example, the volume-based median diameter (D ₅₀ ) is preferably 2 to 9 μm, more preferably 4 to 7 μm.
The volume-based median diameter of the core particles is measured by “Coulter Multisizer 3” (manufactured by Coulter Beckman).

(3) Shelling step In this shelling step, shell resin fine particles are added to the dispersion of core particles to aggregate and fuse the shell resin fine particles on the surface of the core particles, and a shell layer is formed on the surface of the core particles. The toner base particles are formed by coating.
Specifically, the dispersion of the core particles is added to the dispersion of the shell resin fine particles while maintaining the temperature in the core particle formation step, and the shell resin fine particles are slowly removed over several hours while continuing the heating and stirring. By agglomerating and fusing to the surface of the toner, toner particles are formed by covering the surface of the core particles with a shell layer having a thickness of 100 to 300 nm. The heating and stirring time is preferably 1 to 7 hours, particularly preferably 3 to 5 hours.

(4) Ripening step The shape of the toner particles in the toner can be made uniform to some extent by controlling the heating temperature in the core particle forming step and the shelling step, but in order to further make the shape uniform, the ripening step Go through.
This aging step is controlled by controlling the heating temperature and time so that the surface of the toner base particles formed with a uniform particle size and a narrow distribution has a smooth but uniform shape. Specifically, the heating temperature is lowered in the core particle forming step and the shelling step to suppress the progress of fusion between the resin fine particles to promote leveling, and in this aging step, the heating temperature is lowered. In addition, the toner base particles are controlled to have a desired average circularity, that is, a surface having a uniform shape by extending the time.

(5) Washing step to (6) Drying step The washing step and the drying step can be performed by employing various known methods.

(7) External additive addition step This external additive addition step is a step of adding and mixing external additives as necessary to the dried toner base particles.
The toner base particles prepared through the steps up to the drying step can be used as toner particles as they are, but are known on the surface from the viewpoint of improving charging performance, fluidity, or cleaning properties as a toner. It is preferable to add particles such as inorganic fine particles and organic fine particles and a lubricant as external additives.
Various external additives may be used in combination.

Examples of the inorganic fine particles include inorganic oxide fine particles such as silica fine particles, alumina fine particles, and titanium oxide fine particles, inorganic stearate compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, or strontium titanate and zinc titanate. An inorganic titanic acid compound fine particle etc. are mentioned.
These inorganic fine particles are preferably those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like from the viewpoint of heat-resistant storage stability and environmental stability.

The amount of these external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner base particles.
Examples of the method of adding the external additive include a dry method in which the external additive is added in powder form to the dried toner base particles. Examples of the mixing device include mechanical mixing devices such as a Henschel mixer and a coffee mill. It is done.

Various changes can be added to the above-described toner manufacturing method.
For example, when the core resin contains a polyester resin, from the viewpoint of controlling the wax dispersion diameter d in the obtained toner particles, the dispersion in which the core polyester resin fine particles are dispersed is performed in the same manner as in the shell resin fine particle dispersion preparation step. It is preferable to form the core particles by aggregating the polyester resin particles for core together with the wax-containing styrene-acrylic resin fine particles and the colorant fine particles by the styrene-acrylic resin in the core particle forming step.

Further, for example, the wax is not limited to the method of introducing into the core particles by the mini-emulsion method that is contained during the polymerization of the styrene-acrylic resin that constitutes the core resin as described above. A method of introducing a dispersion of wax fine particles, which is introduced into the core particles by aggregating them together with core resin fine particles not containing wax and colorant fine particles to form core particles in the core particle forming step, is adopted. You can also
In the toner production method of the present invention, it is preferable to employ a method in which the wax is introduced into the core particles by the miniemulsion method.

[Average toner particle size]
The average particle diameter of the toner of the present invention is preferably, for example, 3 to 10 μm in volume-based median diameter (D ₅₀ ). This particle size can be controlled by the concentration of the coagulant used, the amount of organic solvent added, the fusing time, and the composition of the polymer, for example, when the emulsion polymerization aggregation method described later is employed.
When the volume-based median diameter is in the above range, for example, a very minute dot image at a level of 1200 dpi (dpi; number of dots per inch (2.54 cm)) can be faithfully reproduced.

  The volume-based median diameter of the toner particles is measured and calculated using a measuring device in which “Multisizer 3” (manufactured by Beckman Coulter) is connected to a computer system equipped with data processing software “Software V3.51”. Is. Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Then, ultrasonic dispersion was performed for 1 minute to prepare a toner particle dispersion, and this toner particle dispersion was placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Inject with a pipette until the displayed concentration of the measuring device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the frequency value is calculated by setting the number of measured particle counts to 25000 and the aperture diameter to 100 μm, and the particle diameter of 50% from the larger volume integrated fraction is the volume-based median diameter.

[Average circularity of toner particles]
In the toner of the present invention, the arithmetic average value of the circularity represented by the following formula (T) is 0.850 to 0.990 from the viewpoint of improving the transfer efficiency of the individual toner particles constituting the toner. Is preferred.
Formula (T): Circularity = perimeter of perfect circle having projection area equivalent to particle projection image / perimeter of particle projection image

Here, the average circularity of the toner particles is a value measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the toner particles are moistened with an aqueous surfactant solution, and ultrasonic dispersion is performed for 1 minute. After dispersion, HPFP detection is performed in the measurement condition HPF (high magnification imaging) mode using “FPIA-2100”. Measurement is performed at appropriate concentrations of several thousand to 10,000. Within this range, reproducible measurement values can be obtained.

  According to the toner as described above, since the shell layer containing the polyester resin is formed on the surface of the core particle containing the styrene-acrylic resin, basically, the toner has sufficient low-temperature fixability and excellent In addition, since the wax is dispersed in a specific range of dispersion diameter in the toner particles, sufficient fixing and separation properties can be obtained regardless of the type of image support used.

(Developer)
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.
As the carrier, for example, magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Among these, ferrite particles Is preferably used. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin-dispersed carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.
The carrier preferably has a volume average particle diameter of 15 to 100 μm, more preferably 25 to 80 μm.

[Image forming apparatus]
The toner of the present invention can be used in a general electrophotographic image forming method. As an image forming apparatus in which such an image forming method is performed, for example, a photosensitive member that is an electrostatic latent image carrier, A charging means for applying a uniform potential to the surface of the photoconductor by corona discharge having the same polarity as that of the toner, and an electrostatic latent image by performing image exposure on the surface of the uniformly charged photoconductor based on image data. An exposure means for forming an image; a developing means for conveying the toner to the surface of the photoreceptor to visualize the electrostatic latent image to form a toner image; and passing the toner image through an intermediate transfer member as necessary. In this case, a transfer means for transferring to the image support and a fixing means comprising a pair of fixing rollers for fixing the toner image on the image support can be used. Among image forming apparatuses having such a configuration, a color image forming apparatus having a configuration in which image forming units related to a plurality of photoconductors are provided along the intermediate transfer body, in particular, the photoconductors are arranged in series on the intermediate transfer body. It can be suitably used for the tandem type color image forming apparatus.

The toner of the present invention can be suitably used at a relatively low temperature where the fixing temperature (the surface temperature of the fixing member) is 100 to 200 ° C.
Furthermore, the toner of the present invention can be suitably used for a high-speed machine in which the linear velocity of the electrostatic latent image carrier is 100 to 500 mm / sec.

(Image support)
As the image support used in the image forming method using the toner of the present invention, for example, plain paper from thin paper to thick paper, coated paper such as fine paper, art paper or coated paper, and commercially available are commercially available. Various types of printing paper such as Japanese paper and postcard paper can be listed.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto. The wax dispersion diameter d was measured by the same method as described above.
[Toner Production Example 1]
(1) Preparation Step of Core Resin Fine Particle Dispersion (1-1) First Stage Polymerization An anionic surfactant “lauryl” is previously prepared in a reaction vessel equipped with a stirrer, a temperature sensor, a temperature controller, a cooling pipe and a nitrogen introducing device. An anionic surfactant solution in which 2.0 parts by mass of “sodium sulfate” was dissolved in 2900 parts by mass of ion-exchanged water was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. .
After adding 9.0 parts by mass of a polymerization initiator “potassium persulfate (KPS)” to this anionic surfactant solution and adjusting the internal temperature to 78 ° C.,
Styrene 540 parts by mass n-butyl acrylate 154 parts by mass Methacrylic acid 77 parts by mass n-Octyl mercaptan 17 parts by mass A monomer solution [1] was added dropwise over 3 hours. After completion of the dropping, polymerization (first stage polymerization) was carried out by heating and stirring at 78 ° C. for 1 hour to prepare a dispersion of “resin fine particles [a1]”.

(1-2) Second-stage polymerization: formation of intermediate layer In a flask equipped with a stirrer,
Styrene 94 parts by weight n-butyl acrylate 27 parts by weight Methacrylic acid 6 parts by weight n-octyl mercaptan 1.7 parts by weight 51 parts by weight of microcrystalline wax (melting point: 80 ° C.) is added as a wax to 85 ° C. The monomer solution [2] was prepared by heating and dissolving.
On the other hand, a surfactant solution in which 2 parts by mass of the anionic surfactant “sodium lauryl sulfate” was dissolved in 1100 parts by mass of ion-exchanged water was heated to 90 ° C., and the above-mentioned “resin fine particles [ a1] ”in the amount of solids of the resin fine particles [a1] is added in an amount of 28 parts by mass, and then the monomer is dispersed by a mechanical disperser“ CLEAMIX ”(manufactured by M Technique Co., Ltd.) having a circulation path. Solution [2] is mixed and dispersed for 4 hours to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 350 nm, and 2.5 parts by mass of a polymerization initiator “KPS” is added to 110 parts by mass of ion-exchanged water. A dispersion of “resin fine particles [a11]” is prepared by performing polymerization (second stage polymerization) by adding an initiator aqueous solution dissolved in the solution and heating and stirring the system at 90 ° C. for 2 hours. It was.

(1-3) Third-stage polymerization: formation of outer layer Start of dissolving 2.5 parts by mass of polymerization initiator “KPS” in 110 parts by mass of ion-exchanged water in the dispersion of “resin fine particles [a11]” Aqueous agent aqueous solution is added and under the temperature condition of 80 ° C.
Styrene 230 mass parts n-butyl acrylate 78 mass parts Methacrylic acid 16 mass parts n-octyl mercaptan 4.2 mass parts monomer solution [3] was dripped over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was carried out by heating and stirring for 3 hours. Then, it cooled to 28 degreeC and produced "the dispersion liquid of core resin microparticles | fine-particles [A]" by which core resin microparticles | fine-particles [A] were disperse | distributed in the anionic surfactant solution.
The glass transition point of the core resin fine particles [A] was 45 ° C., and the softening point was 100 ° C.

(2) Preparation Step of Shell Resin Fine Particle Dispersion (2-1) Synthesis of Shell Resin (Styrene-Acrylic Modified Polyester Resin B) Four 10-liter capacity equipped with nitrogen introduction tube, dehydration tube, stirrer and thermocouple In the mouth flask,
Bisphenol A propylene oxide 2-mole adduct 500 parts by mass Terephthalic acid 117 parts by mass Fumaric acid 82 parts by mass Esterification catalyst (tin octylate) 2 parts by mass were added and subjected to a polycondensation reaction at 230 ° C. for 8 hours. After reacting for hours and cooling to 160 ° C,
Acrylic acid 10 parts by mass Styrene 30 parts by mass Butyl acrylate 7 parts by mass Polymerization initiator (di-t-butyl peroxide) 10 parts by mass of the mixture was added dropwise with a dropping funnel over 1 hour, and then maintained at 160 ° C. After continuing the addition polymerization reaction for 1 hour, the temperature was raised to 200 ° C. and maintained at 10 kPa for 1 hour, and then the acrylic acid, styrene, and butyl acrylate were removed to remove the styrene-acryl modified polyester resin [1]. Got.
This styrene-acryl-modified polyester resin [1] had a glass transition point of 60 ° C. and a softening point of 105 ° C.

(2-2) Preparation of Shell Resin Fine Particle Dispersion The obtained styrene-acrylic modified polyester resin [1] 100 parts by mass was pulverized with “Landel mill type: RM” (manufactured by Tokuju Kogakusha Co., Ltd.), and 0 prepared in advance. Mixing with 638 parts by mass of sodium lauryl sulfate solution with a concentration of 26 mass%, and ultrasonically dispersing with stirring using an ultrasonic homogenizer “US-150T” (manufactured by Nippon Seiki Seisakusho) at V-LEVEL, 300 μA for 30 minutes, A “dispersion of shell resin fine particles [B]” in which shell resin fine particles [B] having a volume-based median diameter (D ₅₀ ) of 250 nm were dispersed was produced.

(3) Preparation Step of Colorant Fine Particle Dispersion Solution 90 parts by mass of sodium dodecyl sulfate is dissolved in 1600 parts by mass of ion-exchanged water, and 420 parts by mass of carbon black “Mogal L” (Cabot Corporation) while stirring this solution. Is added, and then dispersed using a stirrer “CLEARMIX” (M Technique Co., Ltd.) to disperse the colorant fine particles [C]. Liquid "was prepared. The particle diameter of the colorant fine particles [C] in this dispersion was measured using a Microtrac particle size distribution measuring device “UPA-150” (manufactured by Nikkiso Co., Ltd.), and was 117 nm.

(4) Agglomeration, fusion-maturation-washing-drying-addition of external additives In a reaction vessel equipped with a stirrer, temperature sensor, and cooling tube, "dispersion of core resin fine particles [A]" in terms of solid content 288 parts by mass and 2,000 parts by mass of ion-exchanged water were added, and a 5 mol / liter aqueous sodium hydroxide solution was added to adjust the pH to 10.
Thereafter, 40 parts by mass of “dispersion of colorant fine particles [C]” was added in terms of solid content, and then an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was stirred at 30 ° C. Added over 10 minutes. Thereafter, the temperature was raised after standing for 3 minutes, and the system was heated to 80 ° C. over 100 minutes (temperature raising rate 0.5 ° C./min), and the particle growth reaction was continued while maintaining 80 ° C. . In this state, the particle diameter of the core particles was measured with “Coulter Multisizer 3” (manufactured by Coulter Beckman). When the volume-based median diameter (D ₅₀ ) reached 6.0 μm, “shell resin fine particles 72 parts by mass of [dispersion liquid [B] "was added over 30 minutes, and when the supernatant of the reaction solution became transparent, 190 parts by mass of sodium chloride was dissolved in 760 parts by mass of ion-exchanged water. Aqueous solution was added to stop particle growth. Further, the temperature is raised and the mixture is heated and stirred in a state of 90 ° C. to advance the fusing of the particles, and the average circularity measurement apparatus “FPIA-2100” (manufactured by Sysmex) is used (HPF detection). When the average circularity reached 0.945, the mixture was cooled to 30 ° C. to obtain a “dispersion of toner base particles [1]”.
This “dispersion of toner base particles [1]” is solid-liquid separated with a centrifuge to form a wet cake of toner particles, and the electric conductivity of the filtrate is 5 μS / cm using this centrifuge. It was washed with ion-exchanged water at 35 ° C. until it was transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content became 0.5 mass%.
1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added to the dried toner base particles [1], and a Henschel mixer is added. The toner [1] was prepared by mixing.
The wax dispersion diameter d of the toner particles constituting the toner [1] was measured and found to be 0.43 μm.

[Toner Preparation Example 2]
Toner [2] was prepared in the same manner as in Toner Preparation Example 1 except that Fischer-Tropsch wax (melting point: 94 ° C.) was used instead of microcrystalline wax. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 3]
In the core particle preparation step of aggregation, fusion-ripening-washing-drying-addition of external additive in toner preparation example 1, the amount of “dispersed liquid of core resin fine particles [A]” used is 260 parts by mass in terms of solid content In addition, a toner [3] was produced in the same manner except that the amount of the “dispersion of the shell resin fine particles [B]” was 28 parts by mass in terms of solid content. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 4]
In addition to changing the temperature increase time to 500 minutes (temperature increase rate: 0.1 ° C./min) in the temperature increasing step of the aggregation, fusing-maturation-washing-drying-external additive addition step in Toner Preparation Example 1. Made toner [4] in the same manner. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 5]
In addition to changing the temperature increase time to 200 minutes (temperature increase rate of 0.25 ° C./min) in the temperature increasing step of the aggregation, fusing-maturation-washing-drying-external additive adding step in Toner Preparation Example 1. In the same manner, a toner [5] was produced. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 6]
In the temperature raising step of toner aggregation example 1, aggregation, fusing, aging, washing, drying, and external additive adding step, the temperature raising time was changed to 62.5 minutes (temperature raising rate 0.80 ° C./min). A toner [6] was prepared in the same manner as above. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 7]
In addition to changing the temperature increase time to 200 minutes (temperature increase rate of 0.25 ° C./min) in the temperature increasing step of the aggregation, fusion-ripening-cleaning-drying-external additive addition step in Toner Preparation Example 2. Made toner [7] in the same manner. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 8]
In the temperature rising step of toner aggregation example 2, fusing-fusing-aging-washing-drying-adding external additives, the temperature rising time was changed to 41.7 minutes (temperature rising rate 1.20 ° C./min). A toner [8] was prepared in the same manner as above. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 9]
In the temperature rising step of toner aggregation example 2, fusing-fusing-ripening-washing-drying-adding external additives, the temperature rising time was changed to 29.4 minutes (temperature rising rate 1.70 ° C./min). A toner [9] was prepared in the same manner as above. Table 1 shows the wax dispersion diameter d.

[Toner Preparation Example 10: for comparison]
Comparison was made in the same manner except that the temperature increase rate was changed to 2.0 ° C./min in the temperature increase step of the aggregation, fusion-maturation-cleaning-drying-external additive addition step in toner preparation example 1. Toner [10] was prepared. Table 1 shows the wax dispersion diameter d.

[Developer Production Examples 1 to 10]
(1) Production of carrier 100 parts by mass of ferrite core and 5 parts by mass of copolymer resin particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) were put into a high-speed mixer equipped with stirring blades at 120 ° C. A carrier having a volume-based median diameter of 50 μm was obtained by stirring and mixing for 30 minutes to form a resin coat layer on the surface of the ferrite core by the action of mechanical impact force.
The volume-based median diameter of the carrier was measured with a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathic) equipped with a wet disperser.

(2) Mixing of toner and carrier To each of the toners [1] to [10], the above carrier is added so that the toner concentration becomes 6%. The developer [1] to [10] was produced by mixing at a rotational speed of 45 rpm for 30 minutes.

  Using the above developers [1] to [10], the low-temperature fixing property, heat-resistant storage property and crushing resistance were evaluated.

(1) Low-temperature fixability In a commercially available color multifunction peripheral “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies), the surface temperature of the lower fixing roller is set so that the surface temperature of the upper fixing belt is in the range of 140 to 170 ° C. Using toner modified so that the temperature can be changed within the range of 120 to 150 ° C., toner is applied on evaluation paper “NPi fine paper 128 g / m ² ” (manufactured by Nippon Paper Industries Co., Ltd.) at a fixing speed of 300 mm / sec. In a fixing experiment in which a solid image having an amount of 11.3 g / m ² is fixed, the fixing temperature (surface temperature of the fixing upper belt) is set to 170 ° C., 165 ° C. until fixing failure due to cold offset is observed. It was repeated while changing so as to decrease in increments of 5 ° C. The lower fixing roller was always set to a surface temperature 20 ° C. lower than the surface temperature of the upper fixing belt. Then, the lowest fixing temperature in the fixing experiment in which fixing failure due to cold offset was not observed was evaluated as the lower limit fixing temperature. In addition, it means that it is excellent in low temperature fixability, so that this fixing minimum temperature is low, and if it is 155 degrees C or less, it will be judged that there is no problem practically and is a pass. The results are shown in Table 1.

(2) Heat-resistant storage stability Take 0.5 g of toner in a 10 mL glass bottle with an inner diameter of 21 mm, close the lid, shake it 600 times at room temperature using a tap denser “KYT-2000” (manufactured by Seishin Enterprise), and then remove the lid. In the removed state, it was left for 2 hours in an environment of temperature 55 ° C. and humidity 35% RH. Next, the toner is placed on a 48-mesh (mesh 350 μm) sieve while being careful not to disintegrate the toner aggregates, set in a powder tester (manufactured by Hosokawa Micron), and fixed with a press bar and knob nut. After adjusting the vibration strength to a feed width of 1 mm and applying vibration for 10 seconds, the amount of residual toner remaining on the sieve was measured, and the toner aggregation rate, which is the ratio of the residual toner amount, was calculated by the following formula (1). In addition, if it is 20% or less, it will be judged that there is no problem practically and it passes. The results are shown in Table 1.
Formula (1): toner aggregation rate (%) = {residual toner amount (g) /0.5 (g)} × 100

(3) Fixing / separating property Using a commercially available color multifunction device “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies), on the evaluation paper “NPi fine paper 128 g / m ² ” (manufactured by Nippon Paper Industries Co., Ltd.) In the fixing separation experiment in which a solid image having a margin is formed, the set toner adhesion amount is 0.5 g / m ² , 0.6 g / m ² , 0.7 g / m ^2. And repeated to change in increments of 0.1 g / m ² . Then, the maximum value of the toner adhesion amount at which the winding phenomenon does not occur was evaluated as the maximum toner adhesion amount that can be fixed and separated. If the maximum toner adhesion amount is 1.0 g / m ² or more, it is judged as acceptable without any practical problem. The results are shown in Table 1.

As is clear from the above results, it was confirmed that the toner of the present invention was superior in both low temperature fixing property, heat resistant storage property and fixing separation property as compared with the comparative toner.

Claims (6)

An electrostatic charge image developing toner comprising toner particles in which a shell layer containing a polyester resin is formed on the surface of core particles in which at least a wax is dispersed in a core resin containing a styrene-acrylic resin. ,
The average dispersion diameter d of the wax in the core particles is 0.25 to 1.00 μm,
The wax is only microcrystalline wax,
The polyester resin contained in the shell layer is a styrene-acrylic modified polyester resin in which a styrene-acrylic polymer segment is bonded to an end of a polyester segment,
The content ratio of the styrene-acrylic polymer segment in the styrene-acrylic modified polyester resin is 5% by mass or more and 30% by mass or less,
In the structural unit derived from the polyvalent carboxylic acid monomer constituting the polyester segment of the styrene-acrylic modified polyester resin, the content ratio of the structural unit derived from the aliphatic unsaturated dicarboxylic acid is 25 mol% or more and 75 mol% or less. An electrostatic charge image developing toner.   In the structural unit derived from the polyvalent carboxylic acid monomer constituting the polyester segment of the styrene-acrylic modified polyester resin, the content ratio of the structural unit derived from the aliphatic unsaturated dicarboxylic acid is 30 mol% or more and 60 mol% or less. The electrostatic image developing toner according to claim 1, wherein   The electrostatic charge image developing toner according to claim 1, wherein the core resin contains a polyester resin.   4. The electrostatic image developing toner according to claim 3, wherein the polyester resin contained in the core resin is the same as the polyester resin contained in the shell layer. The polyester resin contained in the core resin is a styrene-acrylic modified polyester resin in which a styrene-acrylic polymer segment is bonded to an end of a polyester segment,
5. The toner for developing an electrostatic charge image according to claim 3, wherein the content ratio of the styrene-acrylic polymer segment in the styrene-acrylic modified polyester resin is 5% by mass or more and 30% by mass or less. . 6. The structural unit derived from the aliphatic unsaturated dicarboxylic acid is a structural unit derived from one represented by the following general formula (A). Toner for developing electrostatic images.
General formula (A): HOOC- (CR < ¹ > = CR _< ² _> ) _n- COOH
[Wherein, R ¹ and R ² are a hydrogen atom, a methyl group or an ethyl group, and may be the same or different from each other. n is an integer of 1 or 2. ]