JP2011008029A - Toner for flash fixing, electrostatic charge image developer, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for flash fixing, showing excellent fixing property even in repetition of flash fixing.SOLUTION: The toner for flash fixing contains a binder resin, a colorant, a positive charge controlling agent and an IR absorbent expressed by general formula (1) included in a layer comprising a thermoplastic resin having a softening point higher than that of the binder resin. In formula (1), Rto Reach represent a hydrogen atom, an unsubstituted or substituted straight-chain, branched or cyclic alkyl group, an unsubstituted or substituted straight-chain, branched or cyclic alkenyl group or an unsubstituted or substituted aralkyl group; and Xrepresents an anion.

Description

  The present invention relates to a toner for photofixing, an electrostatic charge image developer, and an image forming apparatus.

  Since the speed of continuous-sheet paper printers is increasing and the load on the paper is small, the light fixing method is often used. In recent years, demand for full color has increased, and devices using a light fixing system in a continuous-book full color system have been put on the market.

The toner used for photofixing contains an infrared absorber to improve fixability by light. For example, the binder resin contains a polyester resin, a first wax having a melting point of 62 to 95 ° C., a second wax having a melting point of 100 to 150 ° C., a colorant and an infrared absorber, and the toner has a tan δ of 3 at 120 ° C. No. 6 color toners for non-contact heat fixing are proposed (for example, see Patent Document 1).
Further, two types of binder resin, which are a first polyester resin having a softening point of 90 to 110 ° C., a second polyester resin having a softening point of 120 to 140 ° C., a colorant, a cyanine compound, and an aminium compound. And a non-contact heat fixing color toner having a maximum absorbance of the toner in the wavelength range of 810 to 870 nm is more than twice the maximum absorbance of the toner in the wavelength range of 870 to 1000 nm (for example, , See Patent Document 2.)
Further, a toner for light fixing containing an infrared absorber treated with a coupling agent (see, for example, Patent Document 3), a color toner for light fixing in which an infrared light absorber is held in wax (for example, a patent) Reference 4) is disclosed.

  As a method for producing a toner for photofixation, an infrared light absorbent is primarily dispersed in a non-crosslinked polyester resin, and further melted together with a toner raw material containing a binder resin and a colorant different from the non-crosslinked polyester as essential components. A method of kneading and pulverizing is disclosed (for example, see Patent Document 5).

As an improvement in infrared absorptivity, an infrared absorptive compound that effectively laminates near infrared rays by laminating multiple layers of metal oxide films, metal films, etc. on the surface of composite fine particles has been proposed (for example, Patent Documents). 6).
In addition, a phase transition material (for example, a wax having a melting point of 100 ° C. or lower) that undergoes a phase transition from a solid to a liquid, from a liquid to a gas, or from a solid to a gas at a predetermined temperature between room temperature and a toner fixing temperature is applied to light. In addition, a toner coated with a thermosetting resin together with a light heating material (for example, carbon) that generates heat upon receipt is disclosed (for example, see Patent Document 7). According to this technique, the photo-exothermic substance expands rapidly due to heat generation and destroys the toner shell, thereby improving the fixability.

Japanese Patent No. 3800201 Japanese Patent No. 4114460 JP 2004-145036 A JP 2002-156775 A JP 2002-357927 A JP 2003-280247 A JP 2005-115194 A

  The object of the present invention is to improve the fixability even if the photofixing is repeated, as compared with the photofixing toner in which the infrared absorber is not included in the thermoplastic resin layer having a softening point higher than the softening point of the binder resin. It is to provide an excellent toner for light fixing.

  The above problem is solved by the following means. That is,

The invention according to claim 1
A binder resin,
A colorant;
A positive charge control agent;
An infrared absorber represented by the following general formula (1) encapsulated inside a layer composed of a thermoplastic resin having a softening point higher than the softening point of the binder resin;
A toner for photofixing.

In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, unsubstituted or substituted linear, branched or cyclic An alkyl group, an unsubstituted or substituted linear, branched or cyclic alkenyl group, or an unsubstituted or substituted aralkyl group is represented, and X ⁻ represents an anion.

The invention according to claim 2
An electrostatic charge image developer containing the photofixing toner according to claim 1.

The invention according to claim 3
A toner image forming means for forming a toner image on a recording medium using the photofixing toner according to claim 1;
Light fixing means for irradiating the toner image with light to fix the toner image on the recording medium;
An image forming apparatus having

  According to the first aspect of the present invention, the photofixing is repeated as compared with the photofixing toner in which the infrared absorber is not included in the thermoplastic resin layer having a softening point higher than the softening point of the binder resin. In addition, a toner for photofixing having excellent fixability is provided.

  According to the second aspect of the present invention, compared to the case where the infrared absorber is not included in the thermoplastic resin layer having a softening point higher than the softening point of the binder resin, the fixability can be maintained even when the light fixing is repeated. An electrostatic charge image developer that is excellent in performance is provided.

  According to the invention of claim 3, compared with the case of using the photofixing toner in which the infrared absorber is not included in the thermoplastic resin layer having a softening point higher than the softening point of the binder resin, Provided is an image forming apparatus capable of forming an image having excellent fixability even when fixing is repeated.

It is a graph showing the light absorbency in the infrared region vicinity about the infrared absorber represented by General formula (1), and its reduced form. (A), (B), and (C) are the schematic diagrams explaining 1st, 2nd, and 3rd embodiment of the infrared absorber particle included in the thermoplastic resin layer. It is a schematic diagram explaining 4th embodiment of the infrared absorber particle included in a thermoplastic resin layer. It is a schematic diagram explaining 5th embodiment of the infrared absorber particle included in a thermoplastic resin layer. (A), (B), and (C) are the schematic diagrams explaining the 6th, 7th, and 8th embodiment of the infrared absorber particle included in the thermoplastic resin layer. It is a figure explaining the definition of a thermoplastic resin layer. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an exemplary embodiment.

Hereinafter, embodiments of the present invention will be described in detail.
<Toner for light fixing>
The toner for light fixing of the present embodiment (hereinafter sometimes simply referred to as “toner”) has a softening point higher than the softening point of the binder resin, the colorant, the positive charge control agent, and the binder resin. And an infrared absorber represented by the following general formula (1) encapsulated inside a layer composed of a thermoplastic resin (hereinafter sometimes referred to as “thermoplastic resin layer”).

In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, unsubstituted or substituted linear, branched or cyclic An alkyl group, an unsubstituted or substituted linear, branched or cyclic alkenyl group, or an unsubstituted or substituted aralkyl group is represented, and X ⁻ represents an anion.

  As shown in the graph of FIG. 1, the diimonium compound represented by the general formula (1) has a maximum absorption wavelength in the near-infrared region near 1000 nm. Therefore, the toner containing this has light energy in the near-infrared region. Absorbs effectively. Therefore, the toner containing the diimonium compound represented by the general formula (1) is fixed by light irradiation.

  However, when the diimonium compound represented by the general formula (1) is reduced, it becomes an aminium compound represented by the following general formula (2) corresponding to a one-electron reductant. Further, when the aminium compound represented by the general formula (2) is reduced, a two-electron reductant represented by the following formula (3) is obtained.

  As shown in FIG. 1, the ability as an infrared absorber, that is, the high absorbance in the near-infrared region, is high for the diimonium compound represented by the general formula (1), and then the aminium represented by the general formula (2). It is a compound, and the two-electron reductant represented by the formula (3) shows almost no infrared absorbing ability.

Here, it has been confirmed by the present inventors that the positive charge control agent contained in the toner has an action of reducing the diimonium compound represented by the general formula (1). Therefore, in a system in which the positive charge control agent and the infrared absorber represented by the general formula (1) coexist in the toner, the infrared ray represented by the general formula (1) when heated at the time of toner production or the like. There is a possibility that the absorbent is reduced by the positive charge control agent and finally reduced to a diatomic reductant that does not exhibit infrared absorption ability.
The positive charge control agent is used to positively charge the toner in accordance with the positive chargeability of the amorphous silicon photoconductor widely adopted from the viewpoint of high surface hardness.

Therefore, in this embodiment, the infrared absorbent represented by the general formula (1) is softened to the binder resin so that the infrared absorbing ability of the infrared absorbent represented by the general formula (1) is not reduced in the toner. It is included inside the thermoplastic resin layer having a softening point higher than the point.
By encapsulating the infrared absorbent represented by the general formula (1) inside the thermoplastic resin layer, the infrared absorbent represented by the general formula (1) is a substance having a reducing action such as a positive charge control agent. The infrared absorption ability is not easily lowered even when heated during the manufacture of toner. In particular, the thermoplastic resin layer is made of a resin having a softening point higher than the softening point of the binder resin of the toner, so that it becomes difficult to be softened by heating such as during toner production, and contact with a positive charge control agent or the like. Effectively prevent. On the other hand, since the layer is composed of a thermoplastic resin, it is difficult to inhibit fixability during photofixing.

As described above, the photofixing toner according to the exemplary embodiment is represented by the general formula (1) included inside the layer formed of the thermoplastic resin having a softening point higher than the softening point of the binder resin. Since it contains an infrared absorber, it has excellent fixability even after repeated use.
The details of the photofixing toner of this embodiment will be described below.

(Binder resin)
As the binder resin in the present embodiment, a known binder resin may be used. The main component of the binder resin is a copolymer of styrene and acrylic acid or methacrylic acid, polyvinyl chloride, phenol resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyolefin resin, polyurethane resin. Polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin, polyether polyol resin, etc. are used alone or in combination.
From the viewpoint of durability and translucency, a polyester resin or a polyolefin resin is preferable, and a polyester resin or a norbornene polyolefin resin is more preferable.

  The polyester resin suitable for the present embodiment will be further described. The acid component used in the polyester resin includes, for example, terephthalic acid, isophthalic acid, orthophthalic acid, or anhydrides thereof, and preferably terephthalic acid / isophthalic acid. It is an acid. These acid components may be used alone or in combination of two or more. In addition, other acid components may be used in combination with the above acid components as long as the odor does not become a problem at the time of photofixing. Examples of other acid components include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, and the like. -Butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl Examples also include alkyl or alkenyl succinic acids such as succinic acid, anhydrides of these acids, lower alkyl esters, and other divalent carboxylic acids. In addition, in order to crosslink the polyester resin, a trivalent or higher carboxylic acid component can be mixed and used as another acid component. Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, other polycarboxylic acids, and anhydrides thereof.

  Further, in the polyester resin, usually, 80 mol% or more of the alcohol component is composed of a bisphenol A alkylene oxide adduct, desirably 90 mol% or more, and more desirably 95 mol% or more.

  Examples of the bisphenol A alkylene oxide adduct include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4). -Hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane Etc. These compounds may be used alone or in combination of two or more.

  In the polyester resin used as the binder resin in the present embodiment, other alcohol components may be used in combination with the above alcohol components as necessary. Examples of other alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1 , 5-pentanediol, diols such as 1,6-hexanediol, and other dihydric alcohols such as bisphenol A and hydrogenated bisphenol A.

  In addition, trihydric or higher alcohols are also suitable as other alcohol components. Examples of the alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1, Examples include 2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and other trivalent or higher alcohols.

  Further, in the reaction for synthesizing such a polyester resin, in order to accelerate the reaction, a commonly used esterification catalyst such as zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, titanium, etc. is used. Advantageously used. Titanium compounds provide particularly good color reproducibility and are optimal for photofixing.

The Tg (glass transition temperature) of the binder resin used in the toner described above is preferably in the range of 50 ° C. or higher and 70 ° C. or lower.
The Tm (softening point) of the binder resin is preferably 80 ° C. or higher and 150 ° C. or lower, more preferably 100 ° C. or higher and 140 ° C. or lower, from the viewpoint of fixability.

(Infrared absorber)
The infrared absorber in this embodiment is a compound represented by the following general formula (1).

In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, unsubstituted or substituted linear, branched or cyclic An alkyl group, an unsubstituted or substituted linear, branched or cyclic alkenyl group, or an unsubstituted or substituted aralkyl group is represented, and X ⁻ represents an anion.

The alkyl groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently preferably an alkyl group having 1 to 10 carbon atoms. And an alkyl group having 2 to 7 carbon atoms is more preferable, and an alkyl group having 3 to 4 carbon atoms is more preferable.
The alkyl group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ is preferably an unsubstituted alkyl group, and is a linear or branched alkyl group. It is desirable that

The alkenyl groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently preferably an alkenyl group having 2 to 10 carbon atoms. More preferably an alkenyl group having 2 to 7 carbon atoms, and still more preferably an alkenyl group having 3 to 4 carbon atoms.
The alkenyl group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ is preferably an unsubstituted alkenyl group, and a linear or branched alkenyl group. It is desirable that

The aralkyl groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently preferably an aralkyl group having 7 to 10 carbon atoms. is there.
The aralkyl group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ is preferably an unsubstituted aralkyl group.

Among these, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogen atoms, or unsubstituted or substituted linear, branched or cyclic alkyl groups. Is more preferably a hydrogen atom, an unsubstituted linear or branched alkyl group, more preferably an unsubstituted linear young or branched alkyl group, particularly an n-butyl group, iso- A butyl group or an n-propyl group is desirable.

Examples of the anion represented by X ⁻ include perchlorate ion (ClO ₄ ⁻ ), boron fluoride ion (BF ₄ ⁻ ), trichloroacetate ion (CCl ₃ COO ⁻ ), and trifluoroacetate ion (CF _3). COO ⁻ ), picric acid ((NO ₂ ) ₃ C ₆ H ₂ O ⁻ ), benzenesulfonate ion (C ₆ H ₅ SO ₃ ⁻ ), ethanesulfonate ion (C ₂ H ₅ SO ₃ ⁻ ), phosphate ion (PO ₄ ²⁻ ), sulfate ion (SO ₄ ²⁻ ), trifluorosulfonic acid ion (CF ₃ SO ₃ ⁻ ), trifluorosulfonic acid bisimide ion ((CF ₃ SO ₂ ) ₂ N ⁻ ), hexafluoro Examples thereof include phosphate ion (PF ₆ ⁻ ), C (SO ₂ CF ₃ ) ₃ ⁻ , and nitrate ion (NO ₃ ⁻ ).
Among these, from the viewpoint of stability when encapsulated inside the thermoplastic resin layer, perchlorate ions (ClO ₄ ⁻ ), fluoroborate ions (BF ₄ ⁻ ), trifluorosulfonate ions (CF ₃ SO ₃ ⁻ ) is preferable, and perchlorate ion (ClO ₄ ⁻ ) and trifluorosulfonic acid ion (CF ₃ SO ₃ ⁻ ) are more preferable.

  Furthermore, in addition to the infrared absorbent represented by the general formula (1), a known infrared absorbent may be used in combination with the photofixing toner of this embodiment. Here, the infrared absorber refers to a material having at least one strong light absorption peak in the near infrared region of 800 nm or more and 1200 nm or less when measured with a spectrophotometer or the like, and may be organic or inorganic.

Specific examples of other infrared absorbers include cyanine compounds, merocyanine compounds, benzenethiol metal complexes, mercaptophenol metal complexes, aromatic diamine metal complexes, nickel complex compounds, phthalocyanine compounds, anthraquinone compounds. Naphthalocyanine compounds, croconium compounds and the like are used.
Among other infrared absorbers, a naphthalocyanine compound or a croconium compound is preferable from the viewpoint of stability when encapsulated inside the thermoplastic resin layer.

  The addition amount of the infrared absorber is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less in the toner for photofixing, and 0.2% It is further desirable that the content is not less than mass% and not more than 2.0 mass%.

(Thermoplastic resin layer)
In the present embodiment, the infrared absorber represented by the general formula (1) is encapsulated inside by the thermoplastic resin layer. Here, a thermoplastic resin layer covers the infrared absorber represented by General formula (1).
As an example, FIGS. 2 (A), (B) and (C) show first, second and third embodiments of infrared absorbent particles having a thermoplastic resin layer, and FIG. An embodiment is shown, and FIG. 4 shows a fifth embodiment. Furthermore, FIGS. 5 (A), (B) and (C) show sixth, seventh and eighth embodiments. In addition, these figures are schematic diagrams for demonstrating the infrared absorber particle | grains which have a thermoplastic resin layer, and this invention is not limited by these figures.

In the first embodiment shown in FIG. 2A, the thermoplastic resin layer 12 covers the surfaces of the primary particles 14 of the infrared absorbent represented by the general formula (1).
With the form which coat | covers the primary particle | grains of an infrared absorber shown in FIG. 2 (A), the usage-amount of the thermoplastic resin used as a thermoplastic resin layer can be restrained small. As a result, even if the thermoplastic resin layer is provided, it is possible to suppress the amount of light energy reaching the infrared absorbent from being lowered.

In the second embodiment shown in FIG. 2B, the infrared absorbent particles 14 represented by the general formula (1) are coated in an aggregated state.
In the form of covering the aggregated particles of the infrared absorbent shown in FIG. 2B, the density of the infrared absorbent is partially increased, so that the conversion from light energy to heat energy at the time of fixing is performed efficiently.

In the third embodiment shown in FIG. 2C, the infrared absorber particles 14 represented by the general formula (1) are held by a resin 16 having a softening point lower than that of the resin of the thermoplastic resin layer. Further, this is coated with a thermoplastic resin having a softening point higher than that of the binder resin.
In the form shown in FIG. 2 (C) in which the infrared absorber is coated together with the other components 16, the resin melting proceeds quickly, so that the fixability is further superior.

Moreover, as shown in FIG. 3, the form by which the particle | grains 14 of the infrared absorber represented by General formula (1) are included inside the microcapsulated thermoplastic resin layer 13 may be sufficient.
In the form of encapsulating the infrared absorber by microencapsulating as shown in FIG. 3, it is possible to effectively prevent contact between the infrared absorber and a substance having a reducing action such as a positive charge control agent. Is significantly reduced.

  Furthermore, as shown in FIG. 4, the thermoplastic resin layer may be a multilayer of two or more layers. In the case of providing two or more thermoplastic resin layers, it is sufficient that at least one layer is made of a thermoplastic resin having a softening point higher than the softening point of the binder resin. More preferably, it is made of a thermoplastic resin having a softening point higher than that of the binder resin.

  Further, as shown in FIGS. 5A, 5B, and 5C, first, the surface of the infrared absorber is covered with the thermoplastic resin layer 12 as shown in FIGS. 2A, 2B, and 2C, and further, 3 may be microencapsulated as shown in FIG. In this case, at least one of the thermoplastic resin layer 12 provided on the surface of the infrared absorber and the microencapsulated thermoplastic resin layer 13 is a thermoplastic resin having a softening point higher than the softening point of the binder resin. It is preferable that the thermoplastic resin layer 13 at least microencapsulated is made of a thermoplastic resin having a softening point higher than the softening point of the binder resin. It is more preferable that both the thermoplastic resin layer 12 and the microencapsulated thermoplastic resin layer 13 are made of a thermoplastic resin having a softening point higher than the softening point of the resin.

When the thermoplastic resin layer is thin, as shown in FIG. 6, there may be a surface portion that is not partially covered with the infrared absorbent represented by the general formula (1) (for example, Since the thermoplastic resin layer covering the infrared absorbent particles is formed on the other surface portion (for example, the portion indicated by Q in FIG. 6), such an embodiment is also present in this embodiment. The thermoplastic resin layer in the embodiment is used.
That is, the thermoplastic resin layer in the present embodiment is a layer shape in which at least one particle of the infrared absorber represented by the general formula (1) is covered so as to be separated from a substance having a reducing action such as a positive charge control agent. The structure of

The resin constituting the thermoplastic resin layer is a thermoplastic resin having a softening point higher than the softening point of the binder resin described above.
Specifically, copolymers of styrenes and acrylic acids, polyvinyl chloride, phenolic resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyolefin resin, polyurethane resin, polyamide resin, furan resin An epoxy resin, a xylene resin, a polyvinyl butyral, a terpene resin, a coumarone indene resin, a petroleum resin, a polyether polyol resin, or the like is used alone or in combination.
More preferable from the viewpoints of adjusting thermal characteristics and toner manufacturability are copolymers of styrenes and acrylic acids, polyester resins, epoxy resins or acrylic resins, and methacrylic resins. Copolymerization of styrenes and acrylic acids. It is more preferred to use a coalescence, polyester resin, or epoxy resin.

In the copolymer of styrenes and acrylic acids used for the thermoplastic resin layer, examples of styrenes include styrenes such as styrene and parachlorostyrene; vinylnaphthalene and the like. These may be used alone or in combination of two or more.
Examples of the acrylic acid in the copolymer of styrenes and acrylic acids include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-acrylic acid 2- Methylene aliphatic carboxylic acid esters such as chloroethyl, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; acrylonitrile; methacrylonitrile; acrylamide; methacrylic acid, acrylic acid, cinnamic acid Vinyl carboxylic acids such as carboxyethyl acrylate, etc., and more preferably, methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like. A down aliphatic carboxylic acid esters. These may be used alone or in combination of two or more.

  The copolymerization ratio of styrenes and acrylic acids is not particularly limited as long as the softening point of the resulting copolymer is higher than the softening point of the binder resin, but from the viewpoint of compatibility with the binder resin during photofixing. Is preferably styrenes: acrylic acids = 95 mol%: 5 mol% or more and 50 mol%: 50 mol% or less, and 90 mol%: 10 mol% or more and 70 mol%: 30 mol% or less. More desirable.

  The epoxy resin used for the thermoplastic resin layer is a compound having two or more oxirane rings (epoxy groups) in the molecule. As an epoxy resin used for a thermoplastic resin layer, a bisphenol A type epoxy resin and a novolac type epoxy resin are preferable, and a bisphenol A type epoxy resin is more preferable. These may be used alone or in combination of two or more.

Examples of the bisphenol A type epoxy resin include those synthesized from bisphenol A and epichlorohydrin.
Generally, an epoxy resin is obtained in a liquid or solid state depending on its molecular weight. In view of covering the particles of the infrared absorbent represented by the general formula (1), a solid epoxy resin is desirable.

  Examples of the polyester resin used for the thermoplastic resin layer include the polyester resins described for the binder resin. However, the polyester resin used for the thermoplastic resin layer is selected so as to be higher than the softening point of the polyester resin selected as the binder resin. In order to increase the softening point, the molecular weight is increased or the three-dimensional structuring is performed by condensation polymerization such as trimellitic acid.

  When the binder resin of the toner is formed of a polyester resin and the thermoplastic resin layer of the infrared absorber is also formed of a polyester resin, each polyester resin is synthesized from the same monomer raw material, It is preferable to use those having different softening points from the viewpoint of compatibility during photofixing.

The softening point of the thermoplastic resin in the thermoplastic resin layer is higher than the softening point of the binder resin, preferably 20 ° C or higher, more preferably 30 ° C or higher and 100 ° C or lower, more preferably 30 ° C or higher. More preferably, the temperature is 60 ° C. or lower.
In addition, the softening point (Tm) of the thermoplastic resin in the thermoplastic resin layer is preferably 130 ° C. or higher and 200 ° C. or lower, and more preferably 140 ° C. or higher and 180 ° C. or lower, from the viewpoint of photofixability. is there.

  The glass transition temperature (Tg) of the thermoplastic resin in the thermoplastic resin layer is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 60 ° C. or higher and 80 ° C. or lower, from the viewpoint of storage stability.

  The molecular weight of the thermoplastic resin in the thermoplastic resin layer is preferably 3000 or more and 1,000,000 or less, more preferably 5000 or more and 200,000 or less, and 8000 or more as the weight average molecular weight (Mw). More preferably, it is 100,000 or less. The number average molecular weight (Mn) is preferably 1000 or more and 100,000 or less, more preferably 2000 or more and 50,000 or less, and further preferably 3000 or more and 30,000 or less.

Here, the molecular weight is measured under the following conditions.
GPC “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corp.)” was used, and the column was “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corp.)”. THF (tetrahydrofuran) is used as the liquid.
As experimental conditions, the sample concentration is 0.5%, the flow rate is 0.6 ml / min, the sample injection amount is 10 μL, the measurement temperature is 40 ° C., and the IR detector is used. The calibration curve is "polystylene standard sample TSK standard" manufactured by Tosoh Corporation: "A-500", "F-1", "F-10", "F-80", "F-380", "A-2500 ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.
In addition, the molecular weight described in this specification is a value measured by the above method.

  The thickness of the thermoplastic resin layer is desirably 10 nm or more and 2 μm or less, more desirably 50 nm or more and 1 μm or less, and further desirably 100 nm or more and 500 nm or less so as to cover the entire surface of the infrared absorber even if the thickness varies.

The thickness of the thermoplastic resin layer is determined by the following method.
(1) Using a transmission electron microscope, photograph a cross-sectional view of the coated particles having a particle size of 80% to 120% of the volume average particle size measured by the following method at a magnification of 10,000 times.
(2) The photographed photograph is observed to measure the film thickness of the thermoplastic resin layer of each coated particle.
(3) The thickness of the thermoplastic resin layer for 100 coated particles is measured, and the average value is taken as the thickness of the thermoplastic resin layer.

When the surface of the primary particle of the infrared absorber as shown in FIG. 2A is coated with a thermoplastic resin layer, the volume average particle size of the coated particle is preferably 10 nm or more and 5 μm or less, and 50 nm or more and 3 μm or less. More desirably, it is more desirably 100 nm or more and 2 μm or less.
When the surface of the aggregated particles of the infrared absorbent as shown in FIG. 2B is coated with a thermoplastic resin layer, the volume average particle size of the coated particles is preferably 10 nm or more and 5 μm or less, and 50 nm or more and 3 μm or less. Is more preferable, and more preferably 100 nm or more and 2 μm or less.
When coated with a thermoplastic resin layer including components other than the infrared absorber as shown in FIG. 2 (C), the volume average particle size of the coated particles is preferably 10 nm or more and 5 μm or less, and 50 nm or more and 3 μm or less. Is more preferable, and more preferably 100 nm or more and 2 μm or less.
Furthermore, in the case of the microencapsulated coated particles as shown in FIG. 3, the volume average particle diameter of the coated particles is preferably 10 nm to 5 μm, more preferably 50 nm to 2 μm, and further preferably 100 nm to 2 μm. desirable.

The volume average particle diameter D50v of the coated particles is a value obtained using Multisizer II (manufactured by Beckman-Coulter) with an aperture diameter of 50 μm. In this case, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.
More specifically, 0.5 mg to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this is added to 100 ml to 150 ml of the electrolytic solution. To do. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment for 30 seconds or more with an ultrasonic disperser, and the particle size is 2.0 μm or more and 60 μm or less using an aperture having an aperture diameter of 50 μm by the Multisizer II type. The particle size distribution of the particles in the range is measured. The number of particles to be measured is 50,000. For the measured particle size distribution, a cumulative distribution is drawn from the smaller diameter side with respect to the divided particle size range (channel), and the particle diameter at 50% accumulation is defined as the volume average particle diameter D50v.
The volume average particle diameter D50v of the toner described in the present specification is a value measured by the above method.

The coverage of the infrared absorbent with the thermoplastic resin layer is desirably 100% from the viewpoint of preventing the progress of the reduction reaction of the infrared absorbent, but in a practical range, it is 70% or more.
The measurement of the coverage is in accordance with the method for measuring the thickness of the thermoplastic resin layer, observing the cross section of 100 coated particles, measuring the ratio (length standard) of the coating to the entire surface of the infrared absorber, Find the average.

  The amount of thermoplastic resin that forms the thermoplastic resin layer is preferably adjusted in consideration of the thickness of the thermoplastic resin layer, etc., but in general, the mass ratio with respect to the infrared absorber described above, The thermoplastic resin: infrared absorber is preferably from 0.01: 99.99 to 30:70, more preferably from 0.1: 99.9 to 10:90, 0.5 : 99.5 or more and 7:93 or less is more desirable.

(Infrared absorber coating method)
Examples of the method for forming the thermoplastic resin layer enclosing the infrared absorber represented by the general formula (1) include an immersion method, a stirring method, a fluidized bed method, a rolling method, a spray method, a kneader coating method, and the like. A known coating method such as a combination of these is employed.
Specifically, for example, in the immersion method, the infrared absorbent particles are immersed in a solution for forming a thermoplastic resin layer. In the spray method, a solution for forming a thermoplastic resin layer is sprayed on the particle surface of the infrared absorber. In the fluidized bed method, the solution for forming the thermoplastic resin layer is sprayed in a state where the particles of the infrared absorbent are suspended by the flowing air. In the kneader coating method, the infrared absorbent particles and the solution for forming the thermoplastic resin layer are mixed in a kneader coating apparatus to remove the solvent.

  Further, a microencapsulation method is also applied as a method for forming the thermoplastic resin layer. Examples of microencapsulation methods include coacervation method using insolubilization of polymer materials, interfacial polymerization method in which a capsule film is formed by polymerizing at the interface of dispersed particles, in situ polymerization method, and liquid curing coating Examples thereof include known methods such as a method, a suspension coating method in air, and a spray drying method in which droplets are sprayed into a gas to form a capsule film on the surface thereof. Details of these technologies are described in books such as “Takeshi Kondo, New Microcapsules, Their Production, Properties, and Applications Sankyo Publishing”.

  However, the method for forming the thermoplastic resin layer in the present embodiment is not limited to the above method, and two or more different methods may be used in combination.

(Coloring agent)
As the colorant, the following are selected according to the color of the toner.
For example, in cyan toner, as the colorant, for example, C.I. I. Pigment Blue 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 13, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 17, 23, 60, 65, 73, 83, 180, C.I. I. Vat cyan 1, 3 and 20, etc., bitumen, cobalt blue, alkali blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indanthrene blue BC cyan pigment, C.I. I. And cyan dyes such as solvent cyan 79 and 162. Among these, C.I. I. Pigment Blue 15: 3 is more desirable.

  In the magenta toner, as the colorant, for example, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112 114, 122, 123, 163, 184, 202, 206, 207, 209, etc., magenta pigments of Pigment Violet 19, C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 30, 49, 81, 82, 83, 84, 100, 109, 121, C . I. Disper thread 9, C.I. I. Basic Red 1, 2, 9, 9, 13, 14, 15, 17, 17, 18, 22, 23, 24, 27, 29, 32, 34, the same 35, 36, 37, 38, 39, 40, etc. Magenta dyes, etc., Bengala, Cadmium Red, Lead Tan, Mercury Sulfide, Cadmium, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red, Calcium Salt, lake red D, brilliant carmine 6B, eosin lake, rotamin lake B, alizarin lake, brilliant carmine 3B and the like.

  In the case of yellow toner, examples of the colorant include C.I. I. And CI pigment yellow 2, 3, 15, 16, 17, 74, 97, 180, 185, 139, and the like.

  The amount of each colorant added to the photofixing toner is desirably in the range of 2 to 15 parts by mass in 100 parts by mass of the final toner particles prepared by mixing with a binder resin or the like. A range of 3 parts by mass or more and 7 parts by mass or less is more desirable.

(Positive charge control agent)
As the positive charge control agent, known ones are used, and examples thereof include nigrosine dyes, triphenylmethane dyes, quaternary ammonium salts, resins containing quaternary ammonium groups and / or amino groups.
For example, benzylmethylhexyl decyl ammonium, decyl trimethyl ammonium chloride, etc. as quaternary ammonium salts, pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1, 2, 3 as azine compounds Triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine 1,3,5-thiadiazine, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline, a Azin Fast Red FC, Azin Fast Red 12BK, Azin Violet BO, Azin Brown 3G, Azin Light Brown GR, Azin Dark Green BH / C, Azin Deep Black EW and Azin Deep Black 3RL, Nigrosine Nigrosine, nigrosine salt, nigrosine derivative as compound, nigrosine BK, nigrosine NB, nigrosine Z, metal salt of naphthenic acid or higher fatty acid, alkoxylated amine, alkylamide as acid dyes composed of nigrosine compound.
Among these, quaternary ammonium salt compounds, alkoxylated amines, and alkylamides are more preferable.

  The addition amount of the positive charge control agent is preferably 0.01 parts by mass or more and 5 parts by mass or less, and more preferably 0.1 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the whole toner particles. preferable.

(Other ingredients)
In addition, wax may be used as needed for the photofixing toner of this embodiment.
In addition, the toner may be a magnetic toner in which a magnetic material such as iron powder, magnetite, or ferrite is mixed. In particular, in the case of toner, a known white magnetic powder (for example, manufactured by Nippon Steel Mining Co., Ltd.) may be used.

  As the wax to be contained in the photofixing toner of this embodiment, ester wax, polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene is desirable, but polyglycerin wax, microcrystalline wax, paraffin wax, carnauba wax, sazol wax. , Montanic acid ester wax, deacidified carnauba wax, palmitic acid, stearic acid, montanic acid, blandic acid, eleostearic acid, valinalic acid and other unsaturated fatty acids, stearyl alcohol, aralkyl alcohol, bephenyl alcohol, carnauvir Saturated alcohols such as alcohol, seryl alcohol, melyl alcohol, or long-chain alkyl alcohols having a long-chain alkyl group; polyhydric alcohols such as sorbitol Fatty acids amides such as linoleic acid amide, oleic acid amide, lauric acid amide; saturated fatty acid bisamides such as methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide , Unsaturated fatty acid amides such as ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; Aromatic bisamides such as acid amide and N, N′-distearylisophthalic acid amide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap); fat Waxes grafted onto hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid; Fatty acids such as behenic acid monoglycerides and partially esterified products of polyhydric alcohols; hydroxyls obtained by hydrogenation of vegetable oils and fats And methyl ester compounds having a group.

  These waxes may be used alone or in combination of two or more. The amount of wax added in the present embodiment is desirably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the finally produced toner particles, and preferably 1 to 6 parts by mass. It is more desirable to be in the range.

(Method for producing toner for photofixing)
In producing the photofixing toner of the present embodiment, a commonly used kneading and pulverizing method, wet granulation method, or the like may be used. Here, as the wet granulation method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method, soap-free emulsion polymerization method, non-aqueous dispersion polymerization method, in-situ polymerization method, interfacial polymerization method, emulsion dispersion granulation Laws are used.

  In the manufacture of the photofixing toner of this embodiment, a thermoplastic resin layer is formed on the infrared absorbent particles in advance as described above.

  In order to produce the photofixing toner of this embodiment by the kneading and pulverizing method, basically, a step of coating an infrared absorber with a thermoplastic resin having a softening point higher than the softening point of the binder resin, infrared rays A process including a step of preparing a toner composition by mixing an absorbent and the like, and a step of kneading and pulverizing the toner composition by melting and kneading (heating step), cooling and pulverizing into toner particles are performed.

  Usually, in the kneading and pulverization method, a binder resin, an infrared absorber represented by the general formula (1), a pigment or dye as a colorant, and other additives such as a wax and a charge control agent are added to a Henschel mixer, Infrared absorbers, pigments, dyes, and magnetic substances are mixed well by a mixer such as a ball mill and melted and kneaded using a heat kneader such as a heating roll, kneader, and extruder to make the resins compatible with each other. A toner composition in which the toner is dispersed or dissolved is prepared, cooled and solidified, and then pulverized and classified to obtain a toner.

(Toner particles)
The toner particles obtained by the above method preferably have a volume average particle diameter D _{50v in} the range of 3 μm to 15 μm, and more preferably in the range of 3 μm to 10 μm.

The toner for photofixing of this embodiment may be used by mixing toner particles with white inorganic particles for a fluidity improver or the like. The mixing ratio with the toner particles is in the range of 0.01 to 5 parts by mass, preferably in the range of 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles.
Examples of such inorganic particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, Examples thereof include barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like, and silica particles are more preferable. Moreover, you may use together the particle | grains of well-known materials, such as a silica, titanium, resin, an alumina. Further, as a cleaning activator, a metal salt of a higher fatty acid represented by zinc stearate and particles of a fluorine-based high molecular weight substance may be added.
The inorganic particles and, if necessary, desired additives are sufficiently mixed by a mixer such as a Henschel mixer to obtain the photofixing toner of this embodiment.

The photofixable toner of this embodiment has an advantage that it has excellent fixability even when photofixing is repeated in a low temperature environment, and thus is suitably used for both black toner and color toner other than black.
Furthermore, in the photofixable toner of the present embodiment, since the decrease in the infrared absorbing ability of the infrared absorbent represented by the general formula (1) can be suppressed, the amount of the infrared absorbent added may be reduced. . Since the infrared absorber represented by the general formula (1) is colored dark blue, unnecessary coloring and color turbidity can be suppressed by reducing the addition amount of the infrared absorber. Therefore, the photofixable toner of this embodiment in which the addition amount of the infrared absorber is reduced also has an advantage of excellent color reproducibility for color toners other than black.

<Electrostatic image developer>
An electrostatic charge image developer (hereinafter sometimes referred to as “developer”) including the photofixing toner of this embodiment includes a one-component developer composed of the toner particles, or a carrier and the toner. Any of two-component developers may be used.

  Examples of the two-component developer carrier include a resin-coated carrier having a resin coating layer on the surface of the core material. As the core material, known magnetite, ferrite, and iron powder are used. The carrier coating agent is not particularly limited, but a silicone resin system is particularly desirable.

The average particle diameter of the carrier core material is generally preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 80 μm or less.
The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and in the range of 3: 100 to 20: 100. Is more desirable.

<Image forming apparatus>
The image forming apparatus according to this embodiment includes at least a toner image forming unit that forms a toner image on a recording medium using the light fixing toner, and an optical fixing that irradiates the toner image with light and fixes the toner image on the recording medium. Means.

(Toner image forming means)
When an electrophotographic photosensitive member is used as an electrostatic latent image holding member for forming a toner image on a recording medium, for example, it can be performed as follows.
First, the surface of the electrophotographic photosensitive member is charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic charge image. Next, the toner is attached to the electrostatic latent image in contact with or in proximity to a developing roll having a developer layer formed on the surface, thereby forming a toner image on the electrophotographic photosensitive member. The formed toner image is transferred onto the surface of a recording medium such as paper using a corotron charger or the like. Further, the toner image transferred to the surface of the recording medium is fixed by a fixing device, and an image is formed on the recording medium.

  As the electrophotographic photoreceptor, generally, an inorganic photoreceptor such as amorphous silicon or selenium, or an organic photoreceptor using polysilane, phthalocyanine or the like as a charge generation material or a charge transport material is used. A photoreceptor is preferred.

(Light fixing means)
The light fixing unit is not limited as long as it can be fixed by light, and a light fixing device (flash fixing device) is used when the light fixing toner of this embodiment is used.

Examples of the light source used in the optical fixing device include a normal halogen lamp, a mercury lamp, a flash lamp, an infrared laser, and the like. It is desirable emission energy of the flash lamp is in the range of 1.0 J / cm ² or more 7.0J / cm ² or less, and more desirably at 2J / cm ² or more 5 J / cm ² or less.

Here, the emission energy per unit area of flash light indicating the lamp intensity of xenon is expressed by the following equation (1).
S = ((1/2) × C × V ² ) / (u × L) × (n × f) (1)

In the above formula (1), n is the number of lamps that emit light at once (f), f is the lighting frequency (Hz), V is the input voltage (V), C is the capacitor capacity (F), u is the process transfer speed (cm / S), L represents the effective light emission width of the flash lamp (usually the maximum paper width, cm), and S represents the energy density (J / cm ² ).

The light fixing method is preferably a delay method in which a plurality of flash lamps emit light with a time difference. This delay system is a system in which a plurality of flash lamps are arranged, each lamp is delayed by about 0.01 ms or more and 100 ms or less to emit light, and an overlapping portion is illuminated a plurality of times. As a result, since the light energy is not supplied to the toner image in one light emission but supplied separately, the fixing conditions are relaxed, and both void resistance and fixing property can be achieved.
Here, when flash emission is performed on the toner a plurality of times, the emission energy of the flash lamp indicates the total amount of emission energy given to the unit area for each emission.

In the present embodiment, the number of flash lamps is preferably in the range of 1 to 20 and more preferably in the range of 2 to 10. The time difference between the plurality of flash lamps is preferably in the range of 0.1 msec to 20 msec, and more preferably in the range of 1 msec to 3 msec.
Furthermore, once emission energy of light emitted in one flash lamp is preferably a 0.1 J / cm ² or more 1 J / cm ² or less in the range, 0.4 J / cm ² or more 0.8 J / cm ² or less It is more preferable that it is in the range.

Hereinafter, an example of the image forming apparatus according to the present exemplary embodiment will be described with reference to the drawings.
FIG. 7 is a schematic diagram illustrating an example of the image forming apparatus of the present embodiment. FIG. 7 shows a toner image formed with toner obtained by adding black to three colors of cyan, magenta, and yellow.

  In FIG. 7, 1a, 1b, 1c and 1d are charging means, 2a, 2b, 2c and 2d are exposure means, 3a, 3b, 3c and 3d are electrostatic image holders (photoconductors), 4a, 4b, 4c and 4d is developing means, 10 is recording paper (recording medium) fed out from the roll medium 15 in the direction of the arrow, 20 is a cyan developing unit, 30 is a magenta developing unit, 40 is a yellow developing unit, 50 is a black developing unit, 70a, 70b , 70c and 70d are transfer means (transfer rolls), 71 and 72 are rolls, 80 is a transfer voltage supply means, and 90 is a light fixing means.

  The image forming apparatus shown in FIG. 7 includes a developing unit (toner image forming unit) for each color indicated by reference numerals 20, 30, 40, and 50 including a charging unit, an exposure unit, a photosensitive member, and a developing unit, and a recording paper 10. Rolls 71 and 72 which are arranged in contact with each other and convey the recording paper 10; and transfer rolls 70a and 70b which are arranged so as to be in contact with the opposite side through the recording paper 10 so as to press the photoreceptor of each developing unit. 70c, 70d, transfer voltage supply means 80 for supplying a voltage to these three transfer rolls, and the side of the recording paper 10 that contacts the photoreceptor on the pressure contact portion between the photoreceptor and the transfer roll in the direction of the arrow in the figure. And an optical fixing device 90 for irradiating light.

  The cyan developing unit 20 has a configuration in which a charging unit 1a, an exposing unit 2a, and a developing unit 4a are arranged around the photoreceptor 3a in a clockwise direction. Further, a transfer roll 70a is disposed opposite to the recording sheet 10 so as to be in contact with the surface of the photosensitive member 3a between the position where the developing unit 4a is arranged on the photosensitive member 3a and the position where the charging unit 1a is rotated clockwise.

  The above configuration is the same for the developing units of other colors. In the image forming apparatus of the present embodiment, the developer containing the cyan toner is stored in the developing unit 4a of the cyan developing unit 20, and the light corresponding to each color is supplied to the developing units of the other developing units. Fixing toner is stored.

Next, image formation using this image forming apparatus will be described.
First, in the black developing unit 50, the surface of the photoreceptor 3d is charged by the charging unit 1d while rotating the photoreceptor 3d in the clockwise direction. Next, the surface of the charged photoreceptor 3d is exposed by the exposure means 2d, whereby a latent image corresponding to the black component image of the original image to be copied is formed on the surface of the photoreceptor 3d. Further, the black toner stored in the developing means 4d is applied on the latent image to develop it to form a black toner image. In the yellow developing unit 40, the magenta developing unit 30, and the cyan developing unit 20, a process similar to this is performed, and a toner image of each color is formed on the surface of the photosensitive member of the developing unit.

  The toner images of the respective colors formed on the surface of the photoreceptor are sequentially transferred onto the recording paper 10 conveyed in the direction of the arrow by the action of the transfer potential by the transfer rolls 70a, 70b, 70c and 70d, and correspond to the original image information. In this way, the toner images are laminated on the surface of the recording paper 10 to form a color toner image in which cyan, magenta, and yellow are laminated in this order from the top layer.

  Next, the laminated toner image on the recording paper 10 is conveyed to the optical fixing unit 90, where it is irradiated with light from the optical fixing unit 90, melted, and optically fixed on the recording paper 10 to form a toner image. It is formed.

<Developer cartridge>
The developer cartridge of the present embodiment is detachable from an image forming apparatus main body provided with a light fixing unit that irradiates and fixes a toner image on the surface of a recording medium, and stores the electrostatic image developer. .
The developer cartridge only needs to include at least one of the developing units 4a, 4b, 4c, and 4d in the image forming apparatus, and the developing units 20, 30, 40, and 50 can also be developer cartridges.

  The toner for photofixing of the present embodiment is suitably used for various applications such as newspapers, service bureaus, barcode printing, label printing, tag printing, Carlson method or ion flow method printers, and copying. Even in the colored embodiment, a product that exhibits good photofixability at low cost is provided.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Preparation of infrared absorber composition>
(Preparation of Infrared Absorber Composition 1) -Comparative Example-
In the infrared absorbent composition 1, the thermoplastic resin layer was not provided and the infrared absorbent was used as it was.
Specifically, as an infrared absorber represented by the general formula (1), a trade name: IRG-023 (manufactured by Nippon Kayaku Co., Ltd.) in which X (counter anion) in the general formula (1) is perchloric acid. Using.
In addition, the shape of IRG-023 used is a particle having an average particle diameter of 100 μm.

(Preparation of Infrared Absorber Composition 2) -Comparative Example-
In the infrared absorbent composition 2, the wax was held with the infrared absorbent.
Specifically, polypropylene wax (trade name: 550P, manufactured by Sanyo Chemical Co., Ltd.) and IRG-023 (infrared absorber represented by the general formula (1)) are mixed at a blending ratio of 50 mass% / 50 mass%. Then kneaded.

(Preparation of Infrared Absorber Composition 3) -Comparative Example-
In the infrared absorbent composition 3, an infrared absorbent surface-treated with a titanium coupling agent was used.
Specifically, 95 parts by mass of IRG-023 (infrared absorber represented by the general formula (1)) and titanium-based coupling agent (trade name: KR46B (tetraoctyl bis titanate), manufactured by Ajinomoto Co., Inc.) 5 masses The portion was put into a Henschel mixer, mixed at 600 rpm for 10 minutes, and then baked at 150 ° C. for 10 minutes to obtain an infrared absorbent composition 3 surface-treated with a fine powder coupling agent.

(Preparation of infrared absorber composition 4)
In the infrared absorbent composition 4, an infrared absorbent coated with a styrene-acrylic resin by a spray method was used.
Styrene-acrylic copolymer resin (St: 75 mol%, BA: 15 mol%, MMA: 10 mol% copolymer resin, molecular weight Mw 100,000, Mn 15,000, Tm is 160 ° C) 5 95 parts by mass of MIBK (methyl isobutyl ketone) was added to parts by mass to adjust the coating solution.
The surface of IRG-023 (infrared absorber represented by the general formula (1)) was coated with a styrene-acrylic copolymer resin by spraying the coating liquid with a spray nozzle. The coating amount was 5 parts by mass of styrene-acrylic copolymer resin with respect to 95 parts by mass of IRG-023.
The average thickness of the thermoplastic resin layer was 0.2 μm. The coverage was 90%. The volume average particle diameter after coating was 1 μm.

(Preparation of infrared absorber composition 5)
In the infrared absorbent composition 5, the infrared absorbent was microencapsulated with an epoxy resin by an interfacial polymerization method.
First, gum arabic was added to water to prepare an aqueous emulsifier solution of 5% by weight of gum arabic. 20 parts by mass of IRG-023 (an infrared absorber represented by the general formula (1)) was mixed with 100 parts by mass of this emulsifier aqueous solution.

Furthermore, bisphenol A type epoxy resin (bisphenol A: 80 parts by mass, epichlorohydrin: 20 parts by mass copolymer resin, molecular weight Mw 80,000, Mn 10,000, Tm is 160 ° C. with respect to 100 parts by mass of the aqueous emulsifier solution. 5 parts by weight of a certain compound and 2 parts by weight of a polyamine compound (trade name: Epomic, manufactured by Mitsui Chemicals) as a crosslinking agent were added. The solution was stirred to allow the crosslinking reaction to proceed, followed by filtration and washing.
The average thickness of the thermoplastic resin layer was 0.2 μm. The volume average particle diameter of the microcapsules was 1 μm.

(Preparation of infrared absorber composition 6)
In the infrared absorbent composition 6, the infrared absorbent was microencapsulated with a polyester resin by an interfacial polymerization method.
In the same manner as the preparation method of the infrared absorbent composition 5, except that a bisphenol A type epoxy resin is used, a polyester resin (bisphenol A-PO: 70 parts by mass, bisphenol A-EO: 30 parts by mass, trimellit Instead of a copolymer resin of acid: 30 parts by mass, terephthalic acid: 70 parts by mass, the molecular weight is 80,000 Mn, and the Mn is 8,000, and the softening point (Tm is 160 ° C.). 6 was obtained.
The average thickness of the thermoplastic resin layer was 0.3 μm. The volume average particle size of the microcapsules was 1.5 μm.

(Preparation of infrared absorber composition 7)
In the infrared absorbent composition 7, the infrared absorbent was coated with a polyester resin by a spray method.
In the same manner as the preparation method of the infrared absorber composition 4, except that a styrene-acrylic copolymer resin was used, a polyester resin (bisphenol A-PO: 70 parts by weight / bisphenol A-EO: 30 parts by weight) Trimerit Instead of acid: 30 parts by weight / terephthalic acid: 70 parts by weight, the molecular weight was Mw 30,000, Mn was 7,000, and the softening point (Tm) was 134 ° C.), and an infrared absorber composition 7 was obtained. .
The average thickness of the thermoplastic resin layer was 0.2 μm. The coverage was 90%. The volume average particle diameter after coating was 1.5 μm.

(Preparation of infrared absorber composition 8)
In the infrared absorbent composition 8, the infrared absorbent was microencapsulated with a polyester resin by an interfacial polymerization method.
In the same manner as the preparation method of the infrared absorbent composition 5, except that a bisphenol A type epoxy resin is used, a polyester resin (bisphenol A-PO: 70 parts by weight / bisphenol A-EO: 30 parts by weight, trimellit 30 parts by weight of acid / 70 parts by weight of terephthalic acid, and a polyamine compound is used as a crosslinking agent, a polycondensation resin in which 5 parts by weight of the polyester is added to 100 parts by weight of the emulsifier aqueous solution and 2 parts by weight of the crosslinking agent is added. The molecular weight was Mw 60,000, Mn 66,000, and the softening point (Tm) was 134 ° C.), and an infrared absorbent composition 8 was obtained.
The average thickness of the thermoplastic resin layer was 0.5 μm. The volume average particle size of the microcapsules was 1.5 μm.

(Preparation of infrared absorber composition 9)
In the infrared absorbent composition 9, the infrared absorbent was coated with an epoxy resin by a spray method.
In the same manner as the preparation method of the infrared absorbent composition 4, except that a styrene-acrylic copolymer resin was used, an epoxy resin (bisphenol A type epoxy resin (bisphenol A: 80 parts by weight, epichlorohydrin: 20 parts by weight)) Infrared absorber composition 9 was obtained in place of a polymer resin of (Mw 80,000, Mn 10,000, softening point (Tm) 140 ° C.).
The average thickness of the thermoplastic resin layer was 0.2 μm. The coverage was 90%. The volume average particle diameter after coating was 1 μm.

(Preparation of infrared absorber composition 10)
The infrared absorbent composition 10 is obtained by microcapsulating an infrared absorbent with a polyester resin by an interfacial polymerization method.
In the same manner as the preparation method of the infrared absorber composition 5, except that a bisphenol A type epoxy resin is used, a polyester resin (bisphenol A-PO: 70 parts by weight / bisphenol A-EO: 30 parts by weight) trimellitic acid : 30 parts by weight / terephthalic acid: 70 parts by weight, using a polyamine compound as a crosslinking agent, a polycondensation resin in which 5 parts by weight of the polyester is added to 100 parts by weight of the emulsifier aqueous solution and 2 parts by weight of the crosslinking agent is added. Infrared absorber composition 10 was obtained instead of the molecular weights of Mw 80,000, Mn 88,000, and softening point (Tm) 140 ° C.).
The average thickness of the thermoplastic resin layer was 0.2 μm. The volume average particle size of the microcapsules was 1.5 μm.

(Preparation of infrared absorber composition 11)
In the infrared absorbent composition 11, the infrared absorbent was coated with a styrene-acrylic resin by a spray method.
In the same manner as the preparation method of the infrared absorber composition 4, except that the styrene-acrylic resin (St: 75 mol%, BA: 15 mol%, MMA: 10 mol% copolymer resin, copolymer resin, molecular weight Mw was 200,000 and Mn was 20,000, and the softening point (Tm) was 180 ° C.), and an infrared absorbent composition 11 was obtained.
The average thickness of the thermoplastic resin layer was 0.2 μm. The coverage was 90%. The volume average particle diameter after coating was 2 μm.

(Preparation of infrared absorber composition 12)
The infrared absorbent composition 12 is obtained by microcapsulating an infrared absorbent with a polyester resin by an interfacial polymerization method.
In the same manner as the preparation method of the infrared absorbent composition 5, except that a bisphenol A type epoxy resin was used (polyester resin (bisphenol A-PO: 70 parts by weight / bisphenol A-EO: 30 parts by weight, tri Mellitic acid: 30 parts by weight / Terephthalic acid: 70 parts by weight, polyamine compound is used as a crosslinking agent, 5 parts by weight of the polyester is added to 100 parts by weight of the emulsifier aqueous solution, and polycondensation is performed by adding 2 parts by weight of the crosslinking agent. Instead of resin, the molecular weight was Mw 100,000, Mn 10,000, and the softening point (Tm) was 180 ° C.), an infrared absorbent composition 12 was obtained.
The average thickness of the thermoplastic resin layer was 0.2 μm. The volume average particle diameter of the microcapsules was 2 μm.

(Preparation of infrared absorber composition 13)
In the infrared absorbent composition 13, after the infrared absorbent is previously coated with a styrene-acrylic resin having a softening point lower than the softening point of the binder resin, this is further softened with a softening point higher than the softening point of the binder resin. Microencapsulated with a thermoplastic resin having
First, in the same manner as the preparation method of the infrared absorber composition 4, except that a styrene-acrylic resin is a copolymer resin of St: 70 mol%, BA: 15 mol%, MMA: 15 mol% (molecular weight: Mw 50,000, In place of Mn 8,000, Tm: 120 ° C.), an infrared absorber was previously coated with a styrene-acrylic resin.
At this time, the average thickness of the thermoplastic resin layer of styrene-acrylic resin was 0.2 μm. The coverage was 90%. The volume average particle diameter after coating was 1.5 μm.
Furthermore, the infrared absorbent coated with styrene-acrylic resin was microencapsulated in the same manner as the preparation method of the infrared absorbent composition 6 to obtain an infrared absorbent composition 13.
The average thickness of the thermoplastic resin layer of the microcapsule was 0.4 μm. The volume average particle diameter of the microcapsules was 2 μm.

(Preparation of Infrared Absorber Composition 14) -Comparative Example-
In the infrared absorbent composition 14, the infrared absorbent was coated with a styrene-acrylic resin having a softening point lower than that of the binder resin.
In the same manner as the preparation method of the infrared absorbent composition 4, except that a styrene-acrylic resin having a softening point (Tm) of 160 ° C. was used instead of a styrene-acrylic resin having a softening point (Tm) of 100 ° C. Infrared absorber composition 14 was obtained.
The average thickness of the thermoplastic resin layer was 0.2 μm. The coverage was 90%. The volume average particle diameter after coating was 1.5 μm.

(Preparation of Infrared Absorber Composition 15) -Comparative Example-
In the infrared absorbent composition 15, the infrared absorbent was microencapsulated with an epoxy resin having a softening point lower than that of the binder resin by an interfacial polymerization method.
In the same manner as the preparation method of the infrared absorbent composition 5, except that an epoxy resin having a softening point (Tm) of 160 ° C. is used instead of an epoxy resin having a softening point (Tm) of 100 ° C. Product 15 was obtained.
The average thickness of the thermoplastic resin layer of the microcapsule was 0.2 μm. The volume average particle diameter of the microcapsules was 2 μm.

[Examples 1 to 12, Comparative Examples 1 to 5]
In Examples 1 to 12 and Comparative Examples 1 to 5, the materials described in Tables 1 and 2 were mixed based on the formulations shown in Tables 1 and 2.
This mixture was melt-kneaded (mixed) at 130 ° C. and 200 rpm with an extruder (Ikegai, PCM-30) to prepare a kneaded product.

Next, the mixture was coarsely pulverized with a hammer mill, finely pulverized with a jet mill, and then classified with an airflow classifier to obtain toner particles having a volume average particle diameter of 4.6 μm.
With respect to 98 parts by mass of each of these toner particles, 1.0 part by mass of hydrophobic silica particles (TG820F, manufactured by Cabot) was externally added by a Henschel mixer, and used for Examples 1 to 9 and Comparative Examples 1 to 4. The toner for photofixing was obtained.

(Development of developer)
A two-component developer was prepared using the obtained toner. As a carrier to be mixed with each toner, a general-purpose ferrite carrier coated with a silicone resin and having a volume average particle size of 40 μm was used. 95 parts by mass of a carrier was mixed with 5 parts by mass of each toner, and mixed for 2 hours in a 10 L ball mill to prepare 3.5 kg of each developer.

<Evaluation>
Using the above developers containing the toners shown in Tables 1 and 2, image evaluation including fixability was performed. As an evaluation device, a modified machine of Fuji Xerox 490/980 Continuous Feed manufactured by Fuji Xerox Co., Ltd. equipped with a xenon flash lamp as a light fixing device (schematic configuration conforms to FIG. 7) was used.
The light emission energy of the flash lamp was 5 J / cm ² . Further, photofixing was performed in an environment of a temperature of 10 ° C. and a humidity of 30%.

(Fixability evaluation)
Plain paper (NIP-1500LT, Kobayashi recording paper) was used as the recording medium, and 5 million images of 1 inch square (2.54 cm × 2.54 cm) were formed by the image forming apparatus. Specifically, each of the photofixing toners shown in Tables 1 and 2 is used, and the amount of toner adhesion (toner applied amount on the recording medium) is adjusted to be 0.5 mg / cm ^{2 in a} single color. 5 million sheets were continuously taken out, and the following fixing rate in this uncleaned fixing device was evaluated.

The fixing rate of the obtained 1-inch square image was evaluated as follows.
First, the status A density (OD1) corresponding to each color of the image is measured, and then an adhesive tape (Scotch Mending Tape, manufactured by Sumitomo 3M) is applied on the image, and then the adhesive tape is peeled off. The status A density (OD2) of the image was measured. In addition, (X-rite 938) was used for the measurement of optical density. Next, the fixing rate was calculated from the following equation (2) using the obtained optical density value.
Fixing rate (%) = (OD2 / OD1) × 100 (2)

The fixing property was evaluated based on the following criteria for the fixing rate calculated from the above equation (2). ○ and △ are acceptable. Tables 1 and 2 show the fixing results.
○: Fixing rate is 95% or more.
Δ: The fixing ratio is 85% or more and less than 95%.
X: The fixing rate is less than 85%.

The components described in Tables 1 and 2 are as follows.
(Pigment)
-Cyan pigment: Pigment Blue 15: 3 (trade name: Blue No. 4, manufactured by Dainichi Seika)
・ Magenta pigment: Pigment Red 122 (trade name: ECR186Y, manufactured by Dainichi Seika Co., Ltd.)
・ Yellow pigment: Pigment Yellow 185 (trade name: Paliotor Y-D1155, BASF)

(wax)
・ Polypropylene wax: Product name 550P (manufactured by Sanyo Kasei)
(Fixing aid)
・ Ester wax: Trade name WEP-9 (manufactured by NOF Corporation)

(Binder resin)
・ Binder resin: Polyester resin (Brand name: FP131, Kao, softening point (Tm) 130 ℃)

(Infrared absorber)
・ Infrared absorber: Diimonium compound, perchloric acid as anion (trade name: IRG-023, manufactured by Nippon Kayaku Co., Ltd.)

(External additive)
・ Silica: Trade name TG820F (Cabot)

(Charge control agent)
Quaternary ammonium salt: Product name PSY (manufactured by Clariant)
Quaternary ammonium salt: Trade name TP415 (manufactured by Orient)

  As shown in Tables 1 and 2, the infrared absorber represented by the general formula (1) is higher than the softening point of the binder resin as compared to the case where the infrared absorbent is not encapsulated in the thermoplastic resin layer (Comparative Example 1). The toners of Examples 1 to 12 encapsulated by a layer composed of a thermoplastic resin having a softening point are fixed in an environment of 10 ° C./30% using an uncleaned fixing device after printing 5 million sheets. The fixing property was maintained when the property was evaluated. As a result, it can be seen that the number of maintenance can be reduced.

From the results of Examples 1 to 12, the thermoplastic resin layer may be formed by spraying with a spray nozzle or microencapsulated by an interfacial polymerization method. Excellent fixability even after repeated use of sheets.
In addition, from the results of Examples 1 to 12, if the thermoplastic resin has a softening point higher than that of the binder resin, the thermoplastic resin layer is composed of any of styrene-acrylic resin, epoxy resin, and polyester resin. Even after repeated use at low temperature fixing, the fixing property was excellent.

  In particular, the infrared absorber represented by the general formula (1) is previously coated with a thermoplastic resin having a softening point lower than the softening point of the binder resin, and this is higher than the softening point of the binder resin. The toner (Example 10) microencapsulated with a thermoplastic resin having a softening point was extremely excellent in fixability.

In contrast, the toner (Comparative Example 2) in which the infrared absorber represented by the general formula (1) is dispersed in wax, and the infrared absorber represented by the general formula (1) are titanium-based coupling agents. The treated toner (Comparative Example 3) improved in fixability as compared with Comparative Example 1, but was much inferior in fixability as compared with Examples 1-12. Further, in the toner (Comparative Examples 4 and 5) coated with a thermoplastic resin having a softening point lower than the softening point of the binder resin (Comparative Examples 4 and 5), the fixing property equivalent to that of Comparative Example 1 or slightly improved. Fixability was shown.
In addition, in order to increase the infrared absorbing ability, the fixing property is improved by increasing the amount of the infrared absorber added in Comparative Example 1. However, the increase in the amount of the infrared absorber added causes color turbidity or changes in color. (Particularly L value decrease) has been confirmed.

According to the result of Comparative Example 2, the infrared absorbing agent represented by the general formula (1) is inferior in fixability under severe conditions of repeated use and fixing at a low temperature if it is simply held in wax. Became clear.
Regarding the result of Comparative Example 3, it is presumed that the titanium-based coupling agent as the surface treatment agent is a thermosetting resin, so that it does not melt at the time of fixing and inhibits fixing.

1a, 1b, 1c, 1d Charging means 2a, 2b, 2c, 2d Exposure means 3a, 3b, 3c, 3d Photoconductors 4a, 4b, 4c, 4d Developing means 10 Recording paper (recording medium)
12, 13 Thermoplastic resin layer 14 Infrared absorbent particles 16 Other components contained in the thermoplastic resin layer 20 Cyan developing unit 30 Magenta developing unit 40 Yellow developing unit 50 Black developing units 70a, 70b, 70c, 70d Transfer means 71 72 Roller 80 Transfer voltage supply means 90 Light fixing means (fixing means)

Claims (3)

A binder resin,
A colorant;
A positive charge control agent;
An infrared absorber represented by the following general formula (1) encapsulated inside a layer composed of a thermoplastic resin having a softening point higher than the softening point of the binder resin;
A toner for photofixing.

[In General Formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, an unsubstituted or substituted linear, branched or A cyclic alkyl group, an unsubstituted or substituted linear, branched or cyclic alkenyl group, or an unsubstituted or substituted aralkyl group is represented, and X ⁻ represents an anion. ]   An electrostatic charge image developer containing the photofixing toner according to claim 1. A toner image forming means for forming a toner image on a recording medium using the photofixing toner according to claim 1;
Light fixing means for irradiating the toner image with light to fix the toner image on the recording medium;
An image forming apparatus.